 Ambiguities are proportional to the strength of the offending backscatter, and as  such, they contribute to the multiplicative noise* ratio (MNR) of the system. Antenna  sidelobes and ambiguities are further suppressed by appropriate weighting in the  processor. The trade-off is lower MNR, at the expense of broader impulse response  width (IRW). 
 M. Weiner, Chapter 9,2 courtesy SciTech ) ch23.indd   24 12/20/07   2:21:42 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 21. no. I. 
 Proc. IRE. vol. 
 FM-CW was applied to the measurement of the height of the ionosphere in  the 1920s32 and as an aircraft altimeter in the 1930s.33  FM-CW altimeter. The FM-CW radar principle is used in the aircraft radio altimeter to  measure height above the surface of the earth. The large backscatter cross scction and the  relatively short ranges required of altimeters permit low transmitter power and low antenna  gain. 
 7 SAW transducer types: ( a) dispersive output, ( b) both input and output dispersive, and   (c) dispersive reflections ch08.indd   10 12/20/07   12:49:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 
 ORY BEHIND THE METHOD AND HOW IT IS APPLIED TO THE ANALYSIS OF REFLECTOR ANTENNAS n  0/ IS A VERY GENERAL hHIGH FREQUENCYv ANALYSIS METHOD THAT GENERALLY PROVIDES HIGH FIDELITY PATTERN PREDICTIONS FOR MOST REFLECTOR SYSTEMS AS LONG AS THE REFLECTOR DIMEN 
 10. Lewis, B. L., J.P. 
 #7 RADAR 4HIS #7 RADAR USES FREQUENCY MODULATION OF THE WAVEFORM TO ALLOW  A RANGE MEASUREMENT 3URVEILLANCE RADAR !LTHOUGH A DICTIONARY MIGHT NOT DEFINE  SURVEILLANCE THIS WAY  A  SURVEILLANCE RADAR IS ONE THAT DETECTS THE PRESENCE OF A TARGET SUCH AS AN AIRCRAFT OR  A SHIP  AND DETERMINES ITS LOCATION IN RANGE AND ANGLE )T CAN ALSO OBSERVE THE TARGET OVER A PERIOD OF TIME SO AS TO OBTAIN ITS TRACK -OVING TARGET INDICATION -4)  4HIS IS A PULSE RADAR  THAT DETECTS MOVING TARGETS  IN CLUTTER BY USING A LOW PULSE REPETITION FREQUENCY 02&  THAT USUALLY HAS NO  RANGE AMBIGUITIES )T DOES HAVE AMBIGUITIES IN THE DOPPLER DOMAIN THAT RESULT IN SO 
 F.: The Continuous-Cathode (Emitting.-Sole) Crossed-Field Amplifier, Proc. IEEE,  vol 61. pp 330 356, March. 
 GRAZING CONDITIONS  THE MODELS MUST ACCOUNT FOR SHADOWING 3IMPLIFIED -ODELS  %ARLY RADAR THEORIES FOR GROUND RETURN ASSUMED  AS IN OPTICS   THAT MANY TARGETS COULD BE DESCRIBED BY A ,AMBERT 
 10 5 0 1 2 5 10 20 50 100(a)(b) (c) (d)(e) f/GHz a)  Bi-polar  Transistor-Amplifier     b)  FET-Amplifier c)  GaAs-Schottky-Mixer,                   d) Parametric Amplifier e)  P-HEMT Amplifier. Radar System Engineering  Chapter 6 – Radar Receiver Noise and Target Detection  30     The antenna noise temperature TAnt, which takes these noise contributions into consideration,  can be calculated, with help from (6.5), by the convolution of the background temperature TB  with the squared directivity  € C(θ,ϕ).  Figure 6.2 shows the convolution. 
 In particular, hydrogen can be present in the interior metal plating and  has been known to cause long-term reliability concerns in some GaAs amplifiers.  One solution involves the use of an internal hydrogen getter to counterbalance the  reliability impact. A getter is a material included in the module housing to absorb  residual hydrogen. 
 J. I).: "Antennas," McGraw-Hill Hook Company, New York. 1950. 
 MEASURING  RADARS ! DOPPLER TRACKING SYSTEM THAT AUTOMATICALLY TRACKS THE FREQUENCY OF A SPECTRAL LINE OF THE ECHO IS SUBJECTED TO TWO PROBLEMS   THERE IS THE POSSIBILITY OF LOCKING ON A FALSE LINE CAUSED BY MOVING PARTS OF THE TARGET AND   WHEN PROPERLY LOCKED ONTO THE AIRFRAME DOPPLER SPECTRUM  THE DOPPLER READING WILL BE NOISY AS DEFINED BY THE RANDOM FLUCTUATION IN INSTANTANEOUS FREQUENCY AS OBSERVED BY THE SPREAD OF THE DOP 
 nckefi. G., and G. W. 
 Rodriguez and J. M. Martin, “Theory and design of interferometric synthetic aperture radar,”  IEE Proceedings , Part F, vol. 
 The beat frequency is amplified and limited to remove any  amplitude fluctuations. The frequency of the amplitude-limited beat note is measured with a  cycle-counting frequency meter calibrated in distance.  In the above, the target was assumed to be stationary. 
 RING ASSEMBLY   WHICH ENDED ITS MISSION IN /CTOBER  AFTER ONLY THREE MONTHS OF OPERATION 3)2 3!2 3ERIES  4HE 3HUTTLE IMAGING RADARS  3)2 
 2 ......... 0.52 3 ~0.5 0.63 0.17 0.7 0.51053 0.17 0.7-5.0 06120 0.02 4.7 145 01 1.030.0 I161.7X._----. RADAR CLUTTER 497  well as the fact that radar waves can penetrate the surface and can be scattered from discon-  tinuities underneath the surface. 
 IMENTAL 2OCKS  SOILS  AND CONCRETE ARE COMPLEX MATERIALS COMPOSED OF MANY DIFFERENT MINERALS IN WIDELY VARYING PROPORTIONS  AND THEIR DIELECTRIC PARAMETERS MAY DIFFER GREATLY EVEN WITHIN MATERIALS THAT  ARE NOMINALLY SIMILAR -OST  EARTH MATERIALS CONTAIN  MOISTURE  USUALLY WITH SOME MEASURE OF SALINITY 3INCE THE RELATIVE PERMITTIVITY OF WATER IS IN THE ORDER OF   EVEN SMALL AMOUNTS OF MOISTURE CAUSE A SIGNIFICANT INCREASE OF THE RELATIVE PERMITTIVITY OF THE MATERIAL ! LARGE NUMBER OF WORKERS HAVE INVESTI 
 FIELD PARTS REPLACEMENT (OWEVER  THE PAYOFF FROM RADARS IN SPACE MORE THAN COMPENSATES FOR THESE CHALLENGES  SINCE SPACE OFFERS A UNIQUE PERSPECTIVE FOR %ARTH OBSERVATION AND IS AN ESSENTIAL VIEWPOINT FOR LUNAR OR PLANETARY EXPLORATION #OVERED AND /MITTED 4OPICS   4HIS CHAPTER INTRODUCES SPACE 
 440 INTRODUCTION TO RADAR SYSTEMS  45. Hynes, R., and R. E. 
 The TEM horn has ultrawideband capabilities from 200 MHz to 4 GHz.  It is positioned above a metallic target buried in the ground as shown in Figure 21.12.  The distance between the horn aperture and the air-ground, interface is 25 cm (different  from the earlier model). 
 Themeansquarevalue(m2)ofthecurrent whenmultiplied bytheresistancet givesthemeanpower.Themeansquarevalueofvoltage timestheconductance isalsothemeanpower.Thevariance isdefined as Il2=(12=«(x-/IId2)"=f(x-11Id21'(x)c1x=1112-11Ii=(x2).v-(x);v(2.14) -co Thevariance isthemeansquaredeviation ofxaboutitsmeanandissometimes calledthe secOIldcentralmoment.Iftherandom variable isanoisecurrent, theproductofthevariance andresistance givesthemeanpowerofthea-ccomponent. Thesquarerootofthevariance (Jis calledthestandard deviation andistheroot-mean-square (rms)valueofthea-ccomponent. Weshallconsider fourexamples ofprobability-density functions: theuniform, gaussian, Rayleigh. 
 A.. and H. T. 
 1)obson: Radar Characteristics of Rirds in Flight. Scic~rtc.cs. vol. 
 TheFTC,orfasttime-constant, actsasadifferen­ tiatingcircuit"orhigh-pass filter,toremovethemeanvalueoftheclutterornoise.This function canbeobtained withamoresophisticated filterconsisting ofaparallelcombination ofintegrator andsubtractor.83Theintegrator isanarrow-band filterthataverages theorderof tenrange-resolution cellstoestablish thebackground level.Areceiver implemented inthis manner hasbeencalledalog-CFAR.' ThetermLOGjCFAR hasbeenappliedtothecell­ averaging CFARwhich-ispreceded Iby:alogarithmic detector.84Thenormalization ofthe threshold isaccomplished inthe'COGjCFAR bysubtraction ratherthanbydivision asinthe conventionalcell-averaging CFAR~Also,theLOGjCF ARiscapableofoperating overalarger dynamic rangeofbackground noiselevels,butithaspoorerdetectability for'thesamenumber ofreference noisesamples thantheconventional cell-averaging CFAR.. DETECTION OF RADAR SIGNALS IN NOISE 3%  CFAR is widely used to prevent clutter and noise interference from saturating the display  of an ordinary radar and preventing targets from being obscured. It is also needed in ADT, or  track-while-scan systems, to prevent the tracking computer from being overloaded by extra-  neous clutter targets or noise. 
 DOMAIN RADAR  TRANSMITS  ON A REPETITIVE BASIS  A SHORT DURATION IMPULSE #ONSEQUENTLY  ITS PEAK POWER IS SIGNIFICANTLY GREATER THAN ITS MEAN POWER 4HIS IS NOT THE CASE WITH STEPPED FREQUENCY WHOSE RADIATED POWER PER SPECTRAL LINE IS HIGHER THAN THE TIME 
 CALIBRATING AND  THEREFORE  RELATIVELY ROBUST IN RESPONSE TO SUCH IMPERFECTIONS )N BRIEF  UNDER THE CONDITION THAT  R    ((   R   66  THE MEAN SIGNAL LEVEL IN THE TWO RECEIVE CHANNELS SHOULD BE  EQUAL )N TERMS OF THE 3TOKES PARAMETERS   3     4HE ( AND 6 BACKSCATTER COEFFICIENTS  WILL ALWAYS BE EQUIVALENT WHEN THE RADARS ILLUMINATION IS PERPENDICULAR TO THE SURFACE (ENCE  ANY HYBRID 
 25–44, 281–298. 11. D. 
 FIG.927.-Four-way r-fswitch used intheAN/MPG-l. The principal elements oftheantenna area5-by15-ft grating reflec- torwhich stands onend, an8-by2-byl-ft convoluted parallel-plate horn whose aperture is5ftfrom thereflector, and arotating waveguide feeding thehorn. The feed, which does not show inFig. 
 The filter whose frequency-response function is  given by Eq. ( 10.1) has been called the North filter, the conjugate filter, or more usually the  matched filter. It has also been called the Fourier transform criterion. 
 NOISE RATIOS AND IS SPECIFIED BY  XJ MXJ K XJ KI II KM IN         
 The usual detection criteria employ the concept of direct probabil-  ity, which describes the chance of an event happening on a given hypothesis. For example, the  probability that a particular radar will detect a certain target under specified conditions is a  direct probability. On the other hand, if an event actually happens, the problem of forming the  best estimate of the cause of the event is a problem in inverse probability. 
  
 In order to obtain the required short-range performance,  it transmits a frame of pulses with differing lengths. Each pulse within the frame is  optimized to cover a specified range bracket. Overall, the pulse sequence completely  covers the instrumented range and ensures that the IMO specified minimum range  requirement is met. 
 The output from one of the antennas was used for transmission and for provid-  ing the range information. with such an arrangement it was difficult to obtain the desired  aperture illuminations and to maintain a stable boresight. A more satisfactory method of  operation is to form the sum and difference patterns in the RF and to process the signals as in a  conventional amplitude-comparison monopulse radar. 
 L. N.: " Radar- System Engineering," McGraw-Hill Book Co., New York. 1947,  pp. 
 Turnstile junc-  tions7 achieve isolations as high as 40 to 60 dB.  The use of orthogonal polarizations for transmitting and receiving is limited to short-  range radars because of the relatively small amount of isolation that can be obtained.'  An important factor which limits the use of isolation devices with a common antenna is  the reflections produced in the transmission line by the antenna. The antenna can never be  perfectly matched to free space, and there will always be some transmitted signal reflected back  toward the receiver. 
 The LFM waveform has a knife-edge ambiguity function with contours that are  approximately elliptical with a major axis defined by the line v = at, where a  = ± B/T  is the LFM slope. This property introduces range-doppler coupling at the matched filter  output causing the matched filter output peak to occur earlier in time for a target with a  positive doppler frequency compared to a stationary target at the same range, assuming  a positive linear frequency modulation slope and later in time for a negative slope.  The compressed pulse shape and SNR are tolerant to doppler shift for the LFM  waveform. 
 2AO BOUND FOR ANGULAR ESTIMATES FOR FLUCTUATING AND NONFLUCTUATING TARGETS  R  IS THE STANDARD DEVIATION OF THE ESTIMATION ERROR  AND  . IS THE NUMBER OF PULSES WITHIN THE  
 SENTS  O  THE NEXT BIT REPRESENTS O  AND SO ON )N THE PHASE ACCUMULATOR  THE TUN 
 PULSE PERIODS  FROM  A SINGLE FREQUENCY REFERENCE 4HIS FULLY COHERENT ARCHITECTURE INSURES THAT BOTH THE DESIRED FREQUENCIES AND ALL THE INTERNALLY GENERATED SPURIOUS SIGNALS ARE COHERENT  ELIMINATING THE DEGRADATION OF CLUTTER REJECTION -ANY RADAR SYSTEMS ARE PSEUDO 
 Thus, when the grid draws current during astrong signal, itdoes not accumulate abias; hence the gain isnot reduced and the amplifier remains sensitive toweak signals. The gain Gofthesingle-tuned stage shown inFig. 12.6 isgiven bythe expression G=g.RL, (2) combined response ofthevideo andi-famplifier) willbetaken autheequivalent i-f amplifier bandwidth unless otherwise stated.. 
 15.7. It can be seen that filters 3 and 4 will provide significant suppression of both clutter sources. FIG. 
 On the other hand, a rough surface will tend to break upthe reﬂection, and will improve the strength of echoes returned from thosetargets whose shape and aspect normally give weak echoes. Composition The ability of various substances to reﬂect radar pulses depends on the intrinsic electrical properties of those substances. Thus metal and water aregood reﬂectors. 
 S #)4 AND   
 Therefore, while the antenna is radiating  less power, individual components must be designed to handle more peak power. With  antennas that do not scan, the mismatch may often be tuned out by conventional tech - niques, preferably at a point as close to the source of the mismatch as possible. In a scanning array, the impedance of a radiating element varies as the array is  scanned, and the matching problem is considerably more complicated. 
 Iftheleakage current at“cutoff” amounts. ‘it. -@,,’@ (ii)’#’tF 5D21 715B 829 3E29 3D21 i .“......---- -....”..—..-.!.—...—-— -—. 
 When this materml isdispensed from aircraft, large volumes of space canbefilled with it.Itfalls ataspeed ofonly afewmales perhour, Tbe strong signals itreturns soeffectively mask theradar signals from aircraft that arc intbemidst ofacloud ofwindow that several tons ofaluminum used tohedispensed. 82 PROPERTIES OFRADAR TARGETS [SEC. 310 FIG. 
 AP-18, pp. 83–88, January 1970.  81. 
 RANGE  PATROL AIRCRAFT $URING THE LATTER PART OF 7ORLD 7AR ))  AIRBOR NE EARLY 
 Ê/ 
 (2.39b)  The probability-density function assumed in cases l and 2 applies to a complex target  consisting of many independent scatterers of approximately equal echoing areas. Although, in  theory, the number of independent scatterers must be essentially infinite, in practice the  number may be as few as four or five. The probability-density function assumed in cases 3 and  4 is more indicative of targets that can be represented as one large rellector together with other  small rellectors. 
    PP n     " $ 3TEINBERG  h(IGH ANGULAR MICROWAVE RESOLUTION FROM DISTORTED ARRAYS v  0ROC )NT #OMPUT  #ONF  VOL      4 # #HESTON AND * &RANK  h0HASED ARRAY ANTENNAS v #HAPTER  IN  2ADAR (ANDBOOK  - ) 3KOLNIK   ED   ND %D  .EW 9ORK -C'RAW 
 BUNCHED IN THEIR CYCLOTRON ORBITS AS A RESULT OF THE RELATIVISTIC MASS CHANGE OF THE ELECTRONS 4HE GYROTRON BUNCHING OPERATION ALSO CAN BE OBTAINED AT HARMONICS OF THE CYCLOTRON FREQUENCY  BUT THERE CAN BE PROBLEMS WITH HIGHER CIRCUIT LOSSES AND COMPETITION WITH MODES OPERATING AT LOWER HARMONICS SO THAT MOST HIGH 
 Automatic Noise-Level Control.  Another widely employed use for AGC is to  maintain a desired level of receiver noise at the A/D converter. As will be described  in Section 6.10, too little noise relative to the quantization increment of the A/D con - verter causes a loss in sensitivity. 
 Side-lobe cancelation in DInSAR pixel selection with SVA. IEEE Geosci. Remote Sens. 
 6.3>b performs this . («) (f) (g) FIG. 6.3 Common reflector antenna types, (a) Paraboloid, (b) Parabolic cylinder, (c) Shaped, (c/) Stacked beam, (e) Monopulse. 
 COVERED AREAS OF 'REENLAND 4HESE RESULTS ARE CONSISTENT WITH PREDICTED SCATTERING COEFFICIENT VARIATIONS BASED ON THE TOPOGRAPHY AND THE ELECTRICAL PROPERTIES OF THE SURFACES 3UBSEQUENTLY  OBSERVA 
 LOG 
 Thus the circuit isstable and uncritical; itonly remains to beshown that the noise contr- ibution ofthe second triode is small. This isnotobvious, and a rigorous proof isbeyond thescope ofthis book (see Vol. 18ofthis series). 
 MENT FOR THE INCUMBENT HARDWARE 2ADAR TRANSMIT WAVEFORMS THAT  PREVIOUSLY HAD BEEN  ARCHITECTED TO MAKE OPTIMUM USE OF THE HIGH PEAK POWER AND LOW DUTY CYCLE CAPABILITY OF THE TUBE NO LONGER FAVOR THE SOLID 
 TO 
 Relative range acc11raq,-typically.2to A km for a target location relative to a known location  observed hy the same radar.  Ahsolute range acrnracy-- lO to 20 km, assuming real-time analysis of the propagation path is  made.  Angil' resoilltion determined hy the beam width; it can be less than 1 ° which corresponds to  50 km at a distance of 3000 km. 
 CLUTTER RATIO IMPROVEMENT AGAINST CLUTTER AT ZERO DOPPLER AS A FUNCTION OF TARGET DOPPLER FREQUENCY /NLY THE RESPONSE OF THE FILTER PROVIDING THE GREATEST IMPROVEMENT IS PLOTTED AT EACH TARGET DOPPLER &OR COMPARISON THE OPTIMUM CURVE FROM &IGURE  IS SHOWN BY A BROKEN LINE AND  THUS PROVIDES A DIRECT ASSESSMENT OF HOW WELL THE #HEBYSHEV FILTER DESIGN PERFORMS AGAINST A GIVEN CLUTTER MODEL !LSO SHOWN IS THE AVERAGE 3#2 IMPROVEMENT FOR BOTH THE OPTIMUM AND THE #HEBYSHEV FILTER BANK &)'52%  #HEBYSHEV &)2 FILTER DESIGN WITH  D" DOPPLER SIDELOBES . 
 Performance Analysis of L-Band Geosynchronous SAR Imaging in the Presence of Ionospheric Scintillation. IEEE T rans. Geosci. 
 Symons, “The constant efficiency amplifier,” NAB Broadcast Engr. Conf. Proc ., 1977,  pp. 
 Fourth, pulse waveforms may be less susceptible to some forms of jamming. ch20.indd   22 12/20/07   1:15:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 fuzes.andmissileguidance. These,aswellasotherapplications. havenotbeenwidely employed because oftheconcomitant limitations thatoccurwithoperation atmillimeter waves. 
 Therefore. the  improvement factor is  (4.25)  Similarly. for a double canceler. 
 ATED AT FREQUENCIES FROM 5(& TO MILLIMETER WAVELENGTHS AND HAVE FOUND USE IN SUCH DIVERSE APPLICATIONS AS AIRPORT SURVEILLANCE RADARS WHERE THE AVERAGE POWERS MIGHT BE MORE THAN ONE KILOWATT  IN AIRBORNE MILITARY AIRCRAFT WHERE THE AVERAGE POWER MIGHT BE OF THE ORDER OF  K7 OR MORE  AND IN LONG RANGE DETECTION OF INTERCONTINENTAL BALLISTIC MISSILES WHERE THE AVERAGE POWER PER TUBE CAN BE GREATER THAN  K7 &IGURE  DEPICTS THE PRINCIPAL PARTS OF A THREE 
 TO 
 Trunk, G.rV.: Comparison of Two Scanning Radar Detectors: The Moving Window and the Feed­ back Integrator, IEEE Trans., vol. AES-7, pp. 395-398, March, 1971. 
    0HOENIX    * 0 #AMPBELL  h"ACK 
 The  diodes attached to the ends or the particular line selected are operated with forward bias to  present a low impedance. The remaining diodes attached to the unwanted lines are operated  with hack-hias to present a high impedance. The switched lines can be any standard RF  transmission line. 
 SURFACE  ! 
 ,/" - $EFINITIONS 4HE INSTANTANEOUS BANDWIDTH OF A COMPONENT IS THE FREQUENCY BAND  OVER WHICH THE COMPONENT CAN SIMULTANEOUSLY PROCESS TWO OR MORE SIGNALS TO WITHIN A  SPECIFIED ACCURACY 7HEN THE TERM  INSTANTANEOUS BANDWIDTH IS USED AS A RADAR RECEIVER  PARAMETER  IT REFERS TO THE RESULTING BANDWIDTH SET BY THE COMBINATION OF 2&  )&  VIDEO   AND DIGITAL FILTERING THAT OCCURS WITHIN THE RECEIVER 7HEN THE RADAR RECEIVER EMPLOYS STRETCH PROCESSING DEFINED LATER IN THIS SEC 
 On one  side you have some indication of the transmitter pulse;  then, a distance along the trace, you have the blip indi-  cating reception of an echo. The distance between these  two objects on the tube is proportional to the actual dis-  tance in space between them; but as a map it is too  elementary to be of any other use than in indicating  range, for we cannot tell which direction is being taken  by the object giving a reflection. Of course, we could  fit either our transmitter or our receiver with a direc-  tional aerial, and by rotation we should be able to get  some idea of azimuth, just as one does in ordinary radio  DF-ing. 
 R. K.: Ioriosplieric Scintillation. Proc. 
 OUT SPECTRAL ENERGY ! #%!  SUCH AS MANUFACTURED BY , 
 TIME 
  CARRIED A PULSE 
 Beforethedevelopment oftheklystronamplifier, theonlyhigh-power transmitter avail­ ableatmicrowave frequencies for\radarapplication wasthemagnetron oscillator. Inan oscillator thephaseoftheRFbearsnorelationship frompulsetopulse.Forthisreasonthe reference signalcannotbegenerated byacontinuously runningoscillator. However, acoher­ entreference signalmaybereadilyobtained withthepower oscill~tor byreadjusting thephase ofthecohoatthebeginning ofeachsweepaccording tothephaseofthetransmitted pulse.The phaseofthecohoislockedtothephaseofthetransmitted pulseeachtimea pulseisgenerated. 
 More complete descriptions will be fourid it1 the Rtrtiur  Ilar~dhook. '  For the most part, this chapter discusses tlie tubes used in radar transmitters and not tlie  transmitters tllemselves. A transmitter is far more than the tube alone. 
 Remote Sens. Lett. 2017 ,14, 1323–1327. 
 QUENCY MODULATION ,&-  WAVEFORM PULSE COMPRESSION IS DISCUSSED 7AVEFORM  SIGNAL ANALYSIS TECHNIQUES  MATCHED FILTER PROPERTIES  AND THE WAVEFORM AUTOCOR 
 BAND -ULTIFUNCTIONAL 2ADAR !RCHITECTURE  !N EXAMPLE -&!2 BLOCK DIAGRAM IS  SHOWN IN &IGURE  4HE MODERN INTEGRATED AVIONIC SUITE CONCEPT BLURS THE BOUNDARIES BETWEEN TRADITIONAL RADAR FUNCTIONS AND OTHER SENSORS  COUNTERMEASURES  WEAPONS  AND COMMUNICATIONS SEE &IGURES  AND  LATER IN THE CHAPTER  4HERE IS A MICROWAVE AND 2& SUITE AN ELECTRO 
 TheRFcircuitry that generates thesumanddifference signalsinamonopulse radarhasbeensteadilyimproved, and canberealized withoutexcessive physical bulk.Apopular formofantenna formonopulse is theCassegrain. Withthe1l10nopulse trackeritispossible toobtainameasure oftheangularerrorintwo coordinates onthehasisofasinglepulse.1\minimum offourpulsesareusuallynecessary with theconical-scan radar.However, acontinuous-tracking radarseldommakesameasurement onasinglepulse.(Phased-array radarsandsomesurveillance radars,however, mightuscthe monopulse principle toextractananglemeasurement onthebasisofasinglepulse.)In practice. thetworadarsutilizeessentially thesamenumberofpulsestoobtainanerrorsignal iftheservotracking bandwidths andpulserepetition frequencies arethesame.Themonopulse radarfirstmakesitsanglemeasurement andthenintegrates anumberofpulsestoobtain therequired signal-to-noise ratioandtosmooth theerror.Theconical-scan radar,onthe otherhand,integrates anumberofpulsesfirstandthenextracts theanglemeasurement. 
 Arapidchangeofcourseislesslikelyforcivilianaircraft: hence.theslower rotation rateof5rpmfortheARSR-3. Thepul~ewidthof2liScorresponds toarangeresolution ofabout300m.(Inpractice, theresoluticfn issaidtobeabout500m.46)Iflimitations onpeakpowerrequireaco'nsidcrably longerpulsewidthinordertoachieve thenecessary energywithinthepulse,someformof pulsecompression couldbeused.(TheARSR-J doesnothavepulsecompression, however.) FM(chirp)isacommon choiceofpulse-compression waveform. The12.8m(42ft)wideby6.9m(22.6ft)highantenna reflector produces al.25°azimuth heamwidth andashapedelevation beamextending beyond40°soastoprovide coverage toan altitude of18.6km(61ft).Theuppercornersoftheantenna aperture haveasquarerather thanrounded outline.Thiscausestheunderside oftheelevation beamtohaveasharpdrop-ofT whichminimizes theground-reflected energythatcausesalobedelevation patternanda degradation oftherain-rejection capability ofcircular polarization. 
 Forcomplete knowledge oftheeffectofpolarization, thepolarization matrixmustbe determined. IfHstandsforlinearhorizontal polarization, 'vforlinearvertical, andifthefirst letterofatwo-letter grouping denotes thetransmitted polarization andthesecondlctter denotes thepolarization ofthereceived signal,thenthepolarization matrixrequires knowl­ edgeoftheamplitudes andphaseofthefollowing components: HH,VV,HVandVH.HV andVHaresometimes calledthecrosspolarization components. IngeneralHV=VHsothat onlyoneneedbedetermined. 
 FERENCE SPIKES  AND WORKS EXTREMELY WELL WHEN THE NOISE HAS A NON 
 EARTH  AND MAY BE GENERALIZED TO CURVED 
 Ridenour, L. N.: "Radar System Engirieering," MIT Radiation Laboratory Series, voi. I, sec. 
 R.. F. L. 
 34!4% 42!.3-)44%23   ££°x WILL NOT hFAILv IN LESS THAN THREE MONTHS HOWEVER  THE COST OF REPLACEMENT MODULES AND  LABOR WOULD BE VERY UNATTRACTIVE BECAUSE NEARLY  OF THE TRANSMITTER WOULD HAVE TO BE REPLACED EVERY YEAR (IGHER -4"&S ARE THUS ESSENTIAL TO ENSURE THAT THE TRANSMITTER IS NOT ONLY AVAILABLE BUT ALSO AFFORDABLE &ORTUNATELY  SOLID 
  2ECORD  /CTOBER   PP n  ' 7 %WELL AND 3 0 :EHNER  h"ISTATIC SEA CLUTTER RETURN NEAR GRAZING INCIDENCE v IN  )%% )NT  #ONF 2ADAR   0UBLICATION .O   ,ONDON  /CTOBER   PP n  ' 7 %WELL  h4ECHNIQUES OF RADAR REFLECTIVITY MEASUREMENT v   #HAPTER  IN  "ISTATIC 2ADAR #ROSS 
 If the surface has a large radius of curvature so that all the radiating elements point to substantially the same direction, then the characteristics are similar to those of a planar array even though the exact 3D position of the element has to be taken into account to calculate the required phase. A small radius of curvature is found with cylindrical (or spherical) arrays used for 360° coverage. Elements are switched to avoid sec- tions of the antenna where they point away from the desired beam direction. 
 58–61. 20. Ken Craig and Mireille Levy, http://www.signalscience.com. 
 The implementation of the adaptive array concept is  more and more related to digital beamforming85–87 and to digital array radar (DAR)  technologies.88,89 Jammer Cancellation and Target Signal Enhancement.  Adaptive array prin - ciples have found a thorough mathematical treatment since the late 1960s83,84; for a  brief history of adaptive arrays, see Reed90; for an overview of least squares adap - tive processing in military applications with celebration of B. Franklin medal to   B. 
 111. F. T. 
 With a scan capability of ?6O0, a minimum of three planar apzr-  tiires, or faces, are required to cover the hemisphere. But when other factors are considered,  more than three faces are usually desired. The greater the number of faces, the less will be the  loss in gain, beam broadening, VSWR variation, polarization change, and the niirnber of  elements per face. 
 15.11 .—AN/APS-l Olow-altitude PPI. Range mark at 10miles; altitude 1600 ft.; Washington, D.C,at0°, 8to13miles. (a) Photograph ofscope. 
 LEVEL $"& WILL HAVE SIGNIFICANTLY BETTER PERFORMANCE THAN SUBARRAY 
 Consequently,  an input pulse shape with very exaggerated slow rise and fall times may be necessary  to achieve the desired output-pulse spectral composition.FIGURE 11.16  Power amplifier combining configurations that provide minimum input port  reflected power: ( a) quadrature-coupled amplifier pair and ( b) split-T amplifier pair with a 90 ° offset.   The amplifier input voltage reflection coefficient is given as Γ and the amplifier voltage gain as   A. (Reprinted with permission from E. 
 (23.36) becomes . A/>r2 var (Pr) - -^- (23.37) 2CT1To This expression is valid for high signal-to-noise cases. Velocity Estimation. 
 D" WIDTH OF THE RETRO 
 This blinking has the effect of introducing artificial glint into the radar tracking cir- cuits, which, if introduced at the proper rate (typically 0.1 to 10 Hz), can cause the radar to break angle track. In addition, blinking has the desirable effect of confusing radiation homing missiles which might be directed against the jammer radiations.12 A self-screening jammer (SSJ) is used to protect the carrying vehicle. This sit- uation stresses the capability of an ECM system relating to its power, signal- processing, and ESM capabilities. 
 Ionospheric outages do not exist in the sense that long-distance illumination is impossible. Path outages are due to defi- ciencies in frequency channel allocations and insufficient radiated power. Addi- tional factors that can affect radar performance are ionization irregularities that degrade path quality and backscatter from spread-in-doppler ionization gradients that can obscure targets. 
 5.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 Multifunctional   Radar Systems   for Fighter Aircraft David Lynch, Jr. 
  .KFT    -KM OR    -KFT 3UPERREFRACTION 
 Trials of ASV Mk. VII [ 3] also made comparisons with these radars. It is of interest to look at these comparative performance results and assess them in the light of modern radar modelling methods. 
 TO 
 WHILE 
 (7.36) corre­ sponds to a diameter of about 1600 wavelengths for maximum gain. The beam width of such an  antenna would be about 0.04° with a gain of about 68 dB.  In practice, the construction tolerance of an antenna is often described by the" peak"  error, rather than the rms error. 
 Angle ^ 1 deg.- = NoiseOCTSSN= 1OTIME= 8 GMTLOCATION 38.65 N LAT 76.53 W LON BEARING= 90.00 OEGOCT SSN = 100 TIME = 8 GMTLOCATION 38.65 N LAT 76.53 W LON BEARING= 90.00 OEG FIG. 24.25 Radar performance estimate; October, 0800 UTC. (a) SSN = 10. 
 The “doorknob” transition ofFig. 11.12bisdesigned tominimize breakdown. Itcan be thought ofasaquarter-wave probe with aspecial form ofstub support forthetipoftheprobe inwhich capacitive and inductive effect have been balanced against each other sothat asasupport itpresents noloading ofthe waveguide. 
 27, no. 2, pp. 188-190, February, 1954. 
 Radar Range Equation.  In the doppler region where the signal does not fall in  clutter, performance is limited only by system noise. The signal-to-noise power ratio  in the range-doppler cell at the detector prior to postdetection integration for a target  at range R is given by  SNR=  R Ro4  (4.15)  RP G G kTB LoT R T s n T=  av λ σ π2 31 4 4( )/  (4.16) where Ro = range at which SNR is equal to 1  sT = target radar cross section  LT = losses applicable to the target The remaining terms are as defined following Eq. 
 10.25. The pulse voltage never rises above thecritical value Vc,because, asitreaches Vs,the magnetron draws current and loads thepulser. If oscillation fails tostart promptly after the pulse voltage hasreached Vs, thevoltage continues torise and may exceed Vcbefore current isdrawn. 
 INCLINATION  n  AND A LONG 
 On two occasions contact was established in complete darkness, at distances of 12 and 20 miles, and on one occasion whenvisibility was only 500 yards, at a distance of 12 miles. Attack : when the cloud base is below 1500 ft an approach from any desired direction can be made to a ship which is otherwise invisible from the aircraft.Thus an element of surprise can be obtained by a diving attack through the clouds, emerging at the last stage at very close range. Considerable experience of the use of ASV was developing and the shortcomings of the existing equipment were becoming clear. 
 This is illustrated in Fig. 19.6«. However, by introducing a frequency offset before the coherent detector,5 the resulting spectrum will be as shown in Fig. 
 &-  &- 
 TIPLE ANTENNAS WITH OVERLAPPING NONSQUINTED  BEAMS POINTED AT THE TARGET )NTERPOLATING TARGET ANGLES WITHIN THE BEAM IS ACCOMPLISHED  AS SHOWN IN &IGURE   BY COMPARING THE PHASE OF THE SIGNALS FROM THE ANTENNAS FOR SIMPLICITY A SINGLE 
 Provided the wind speed is greater than about 3λ kt (with l in meters) and  the sea is fully developed, the clutter cross section s  0 is about –29 dB and is rela - tively independent of wind speed and frequency. (The definition of s  0 in HF radar  is complicated by problems in properly defining antenna gains for ground-wave  and sky-wave paths and by propagation effects due to the ionosphere.) The clutter  spectrum tends to fill in around and between the lines as the wind picks up. For  horizontal polarization (which is possible only for sky-wave paths over which the  plane of polarization can be rotated by the Earth’s magnetic field), the cross section  is much smaller and shows the characteristic fourth-power decay with a decreasing  grazing angle. 
 (c) Variation of frequency with current for the SFD-377A X-band coaxial magnetron at a  frequency of 9.373 GHz, with 0.001 duty cycle, and 1.0 ps pulse width (Courtesy Varian Associates, Inc.,  Beverly, MA.)  RADAR TRANSMITIERS 197 30600.-----r------.--------,r---------,----~ Peakvoltage Efficienc (a)-50 800----------- ------------10---·---I--=----F-----;7'o<C----j40 ;:e !:.... >- ----------1----::::7~-t_---__j30 g <V U ~ ---+---------120 W 400 600 .Average powerinput(Wafts)20025500-- 5100 o~ ~20c400------ ~'SE- O) a300 Q:; ~a100200 -'"a <Vn ------------29 ------------r----f- -------- ----f------ 28 -------------f---t---t--f--- r- oL..--------'-_-l----l_---'-_L..--------'-_-'------"-_-'-----' 245455 56 5_75_8 5_9 Frequency (GHzl N I ::'!:+1 - ---------------------------- 0'c ... c:. 
 C.; Techniques of Radar reflectivity measurement; Artech House; 1984 ;  UB-Ka [ 85A3011]  − Ruck, G. et al; Radar Cross Section Handbook (Band 1 -2); Plenum Press NY; 1970  − Ulaby, F. T. 
 ING OF SEA ICE  WHICH THE SYSTEM HAS BEEN DOING SUCCESSFULLY SINCE    4HE  2USSIAN 8 
 pp. 73-75. January. 
 Sensors 2019 ,19, 1701 Pulse compression needs to eliminate the quadratic term of frin Equation (10), and a matched ﬁlter can be constructed in frequency: Hr(fr)=exp(jπf2 r γ) (11) After multiplication of Equation (9) and Equation (11) to complete pulse compression, the phase after pulse compression is: θ(fr,fa)=−4πRb(fc+fr) c/radicaltp/radicalvertex/radicalvertex/radicalbt1−(cfa)2 4(fc+fr)2v2−2πfaXi v(12) Let kr=4π(fr+fc) c,kx=2πfa v, Formula (12) is rewritten as: θ(kr,kx)=−Rb/radicalBig k2r−k2x−kxXi (13) Since the signal processing of the RMA algorithm is performed in the two-dimensional frequency domain, and Rbrepresents the time domain, the phase compensation cannot handle the change along the range direction. At this time, a reference range is ﬁrst selected, and the phase at the reference distance is compensated. Generally, the reference range is set at the center of the scenario. 
 The rms time-delay error for a trapezoidal-shaped pulse of width 2 T1 across the top, fiat  portion and with rise and fall times of T2 may be shown from Eqs. ( 11.16) and ( 11.17) to be  oTi =(Ti+ JTi T2)112  trapezoidal pulse (11.21)  R 6E/N0  When the trapezoidal pulse approaches in shape the rectangular pulse. that is, when T1 ~ T2,  Eq. 
 CIENT ALGORITHMIC PROCEDURE TO EXTRACT THE WEIGHTS  NAMED )NVERSE  12  IS DETAILED IN  "OLLINI ET AL  /THER POSSIBILITIES ARE TO USE MODERN COMPUTING TECHNOLOGIES LIKE THE  &0'!  0OWER 0#  OR HIGH 
 . 
 At higher frequencies, the plant attenu - ation prevents a significant surface echo, so the angular variation is more uniform.  FIGURE   16. 36 4.5-GHz scattering coefficient versus soil moisture (percent of field capacity) for  vegetation-covered soil ( after F . 
 S. Haykin and A. Steinhardt, Adaptive Radar Detection and Estimation , New York: John Wiley  & Sons, Inc., 1992. 
 Those relative target velocities which result in zero MTI response are called hli~ld  SIIL~LY~S and are given by  nll nllfp v =-=- " 2T 2 n= l,2, 3, ...  where 17, is the nth blind speed. If J. 
 Section 3veriﬁes the correctness of the proposed method based on ENVISAT-1 ASAR and ERS-2 SAR images. The inﬂuence of different radar looks directions, wind directions and wind speeds on SAR eddy imaging are discussed in Section 4. We conclude with a discussion of the applicability of our research for future investigations on shear-wave-generated eddies in Section 5. 
 This [nay  be acconiplislied by providirig tlie PPI-scope operator with a grease pencil to mark tlie target  pips or1 the face of the scope. A line joining those pips tliat correspond to the same target  prcwidcs ttie target track. Wlieti tlie traffic is so dense that operators cannot maintain pace  tvith the irifortnatiori available from the radar, the target trajectory data may be processed  autotnatically iri a digital computer. 
 Xing, M.; Jiang, X.; Wu, R.; Zhou, F.; Bao, Z. Motion Compensation for UAV SAR Based on Raw Radar Data. IEEE T rans. 
 ch16.indd   58 12/21/07   10:26:10 AMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 Although both bands have distinctive advantages for  ship application, when only a single radar is employed it is usually at X band for the reasons  give11 above." I'hus the fact that sea clutter is less at the lower frequencies is but one of several  factors to be collsidered in the selection of the optimum frequency for a particular radar  application.  Polarization. Figure 13.3 indicates that horizontal polarization results in less sea clutter than  vertical, for the sea conditions whicl~ apply to that data. 
 The latter is the more usual of the two possible coordinate systems since it is easier for the  microwave engineer to measure the VSWR and the position of the voltage-standing-wave  minimum (or phase) than it is to measure the conductance and susceptance directly. The  radial coordinate can also be specified by the reflection coefficient r of the load since the  VSWR p and reflection coefficient are related by the equation Irl = (p - l)/(p + 1). The  center of the Smith chart (Rieke diagram) corresponds to unity VSWR, or zero reflection  coeficient. 
 The control element ofthe regulator isasolenoid coil and armature. The current through the solenoid coil isproportional tothe voltage to beregulated, andthe pull ofitscore onthearmature isproportionalto the airgap between the two, and tothe coil current. The air gap isadjustable by movement of120 thecore; this constitutes one ofthe ~ adjustments tobemade onthe &:regulator.~115 With the core infixed position ~ and the pile-adjusting screw tight, ~ theoutput voltage ofthegenerator will behigh. 
 A 24-mm chip would therefore have an expected yield of only 30 percent. 2. Difficulty of impedance matching: Increases in power output are the result of adjacent channels being connected in parallel. 
 1-lock. W. I,.: Monitoring Bird Movements by Radar, IEEE Sl)c~ctrto~r, vol. 
 BAND SOLID 
 D. K. "Radar Systems Analysis," Prentice-Hall, Inc., New Jersey, 1964. 
 Skolnik, M. I., and D. D. 
 The  reduction in radar signal power when propagating over a distance Rand back (two-way path)  may be expressed as exp ( -2et.R), where a. is the (one-way) attenuation coefficient measured in  units of (distance) 1. Instead of plotting a., it is more usual to plot the one-way attenuation in  decibels per unit distance. 
 It has the proper phase <Pm + <Pn  at each element to steer in the two directions. The mixer would be followed by a power  amplifier if a transmitter, or it might be used _to obtain the local Oicillator frequency if a  receiver. Only M + N -2 phase shifters are required, but the mixer and power amplifier  required at each element adds to the complication. 
 4. pp. 116 125. 
 The res~ltant loss with the combining of a large number of devices  in some microwave circuits can sometimes negate the advantage achieved by combining. Thus  as a direct replacement for conventional microwave tubes, solid-state devices have been  limited to low or moderate power applications.  A phased-array transmitting-antenna combines in space the power from each of many  transmitting sources. 
 The approxima- tion is reasonable .when (RT + RR)»L or when L»CTU. Other implementations of pulse chasing are possible. In one concept the n- beam receive antenna is retained and two receiver-signal processors (RSPs) are time-multiplexed across the n beams. 
 sensors Article Extended Multiple Aperture Mapdrift-Based Doppler Parameter Estimation and Compensation for V ery-High-Squint Airborne SAR Imaging Zhichao Zhou1,2, Yinghe Li3, Yan Wang1,2,*, Linghao Li1,2and T ao Zeng1,2 1School of Information and Electronics, Beijing Institute of Technology, Beijing 100081, China; zcz1024@foxmail.com (Z.Z.); lilinghaodhd@foxmail.com (L.L.); zengtao@bit.edu.cn (T.Z.) 2Beijing Key Laboratory of Embedded Real-Time Information Processing Technology, Beijing 100081, China 3Beijing Institute of Radio Measurement, Beijing 100081, China; liyinghe@bit.edu.cn *Correspondence: yan_wang@bit.edu.cn; Tel.: +86-10-6891-8550 Received: 31 October 2018; Accepted: 3 January 2019; Published: 8 January 2019/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: Doppler parameter estimation and compensation (DPEC) is an important technique for airborne SAR imaging due to the unpredictable disturbance of real aircraft trajectory. TraditionalDPEC methods can be only applied for broadside, small- or medium-squint geometries, as they at most consider the spatial variance of the second-order Doppler phase. To implement the DPECin very-high-squint geometries, we propose an extended multiple aperture mapdrift (EMAM) method in this paper for better accuracy. 
 6.14, but itwill beuseful here todescribe afew principal features ofaradar that employs conical scan solely forthepurpose ofheight-finding. This principle was used inthe British CMH, amobile 10-cm equip- ment designed specifically for height-finding. Itused a6-ft dish, a power of500kw, and was capable ofmeasuring heights towithin ~500ft. 
 Here attention will be confined to echoes from airborne and surface targets. Aircraft and ships have dimensions that put them in the resonant scattering region. The smallest aircraft and cruise missiles will be in the Rayleigh scattering region for the lower half of the HF band. 
 The radar operator, observ- ing the existence of an error and its direction, could position the antenna to regain a balance between the two beam positions. This provided a manual tracking loop. This lobing technique was extended to continuous rotation of the beam around the target (conical scan) as in Fig. 
 There have been many methods proposed in the literature for determining  the elerrlent spacings (or locations within the aperture) of such arrays. Only two will be  mentioned here: dynamic prograrnrning and density tapering.  1I1EFI.ITTRONIrAI.IY STEFRED PHASED ARRAY ANTENNA INRADAR331 calarrayalsoattracts attention whenhemispherical coverage isdesired. 
  A     K $  WHEN  $K  4HE FORWARD 
 A radar system that has the ca- pability of changing frequency over a very wide band can, with advantage, adapt its transmission to take into account frequency-dependent multipath characteris- tics, target response, environmental conditions, interference, and jamming. Fur- ther, wideband processing can give fine range resolution. Phased arrays have the potential of operating over very wide bandwidths. 
 Figure 11b is a result of interpolation of the point (1025 −135, 2050−120) in Figure 11a. It can be seen that the point target in forward-looking beam is well focused. The proﬁles of range and azimuth-spread function of the target are presented in Figure 11c,d. 
 d.Estimated number ofaircraft. e.Height. ~.Dhection oftight. 
 For example, if L = 120 km and  hT = 0.3 km, then from Eq. 23.6, the transmitter would only illuminate a target flying  directly above the receiver at an altitude ht > 0.14 km. Thus, the target could readily  under-fly the illumination, and low-altitude air surveillance capability is lost. 
 WIDE FIGURE 
 By "ideal" conditions is meant an antenna with negligible  sidelobes and negligible resistive losses, and which looks at a distributed source of brightness  teuiperature (the cosmic noise) in the absence of the earth's atmosphere or any other  source of noise. For a practical antenna the antenna temperature is defined as the integral  of the brightness temperature over all angles, weighted by the antenna pattern.  Atmospheric absorption noise. 
 267 Focused SAR.519 Forward scatter.557 Foxphaseshifter.296-297 Fraunhofer region.anlenna. 229INDEX575 Frequency agility: ECCM.548 forglintreduction, 170-172 andseaecho,485 Frequency diversity, 548 Frequency measurement accuracy, 407-408 Frequency modulated CWradar,81-92 Frequency-scan arrays,298-305 Frequency-scan radar.andpulsecompression. 433 Fresnelregion,antenna, 229 Fresnelzoneplate,523.527 Gain.antenna. 
 13.2 and 13.12, may be considered real and related to differences in grazing angle rather than in resolution cell size. In fact, distributions closely resembling those in Fig. 13.12 were obtained much earlier from similar measurements with considerably broader pulse widths.35 At Very Low Grazing Angles. 
 Finally, a pulse transformer matches the PFN to the  impedance seen at the magnetron cathode. A pulse of around 10 kV is required to fire  the magnetron. In order to get good performance over a wide range of pulse lengths,  designs utilize a great deal of empirically derived knowledge, and actual circuits can  be surprisingly complex. 
 24.1 example, 16 simultaneous receiver-processor channels are required for the multiple receive beams. Figure 24.27c gives the cor- responding power-level distributions. These approximately log-normal distribu- tions are typical. 
 /Ê"Ê 1 /* 
 The spatial scale of the polarization “fringes” in the  radar footprint is typically in the range 10–100 km, and the change of frequency  needed to rotate the plane of polarization by 90 ° at a given location in the radar  footprint (the polarization bandwidth) is of the order of 100 kHz, so differential  ch20.indd   6 12/20/07   1:15:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 
 TIVE MICROWAVE MEASUREMENTS OF A WIDE VARIETY OF SURFACE FEATURES  ENABLED BY THESE MULTICHANNEL CAPABILITIES 4HE FOLLOWING PARAGRAPHS PROVIDE ONLY A GLIMPSE INTO THESE TOPICS THE DISCUSSION IS MEANT TO WHET THE APPETITE OF THE READER AND TO PROVIDE LEADS TO THE VOLUMINOUS LITERATURE )NTERFEROMETRY  )NTERFEROMETRY BY RADAR &IGURE    IMPLIES MEASUREMENTS THAT   ARE BASED ON PHASE DIFFERENCES SENSED THROUGH TWO DIFFERENT OBSERVATIONS OF THE SAME PHENOMENA n 0HASE DIFFERENCES ARISE FROM MICROWAVE 
 2.2). Evidently some sort offanbeam, as narrow aspossible inthehorizontal direction but spread outvertically, is demanded. Tofind theshape which thebeam should have, inavertical plane, theproperties ofthetarget must betaken into account. 
 One example is ARI 5136 [ 8], installed in Barracuda aircraft, which had only homing antennas. A radar interconnection diagram is shown in ﬁgure 2.17. Aerial coupling box type 8 housed the aerial switch unit type 98A, together with spark gaps for receiver protection. 
 Precision of the geoid measurement was specified as ±10 cm.18 The Seasat-A satellite was launched at 6:12 P.M. PST on June 26, 1978. The orbital altitude was 783 km at apogee and 778 km at perigee. 
 20 array simulator for, 13.25 to 13.26 bandwidth of, 13. 38 to 13.45 beam switching, 13.8 calibration of active arrays, 13.60 to 13.62 circular polarization, 13.6 constrained feed, 13.46 Counter Battery Radar (COBRA), 13.62 digital beamforming, 13.56 to 13.57 diode phase shifters, 13.51 to 13.52 and ECM, 24.43 to 24.48 element pattern, 13.22 to 13.23 errors in, 13.30 to 13.38 feed networks, 13.46 to 13.50 ferrite phase shifters, 13.52 to 13.53 frequency scan, 13. 7 to 13.8 gain, 13.13 to 13.15 gr ating lobes, 13.10 to 13.12, 13.17 to 13.19 ground-based, 13.63 to 13.65 illumination functions, 13.28 to 13.29 instantaneous bandwidth, 13.42 to 13.45 limited scan, 13. 
 S.: Paraboloidal Reflector Patterns of Off-axis Feed, IRE Trat~s., vol. AP-8, pp. 368-379,  July, 1960. 
 ,  
 - 4HE AMPLITUDE OF GROUND ECHOES RECEIVED BY RADARS ON MOVING VEHICLES FLUCTUATES WIDELY BECAUSE OF VARIATIONS IN PHASE SHIFT FOR RETURN FROM DIF FERENT PARTS OF THE ILLUMI 
 cc ¯TTT    3MALL 
 Trotter, “Design considerations for the NOAA airborne meteorological radar and data  system,” in 18th Conf. on Radar Meteorol. , AMS, Atlanta, 1978, pp. 
 L. Moffatt: Natural Resonances of Radar Targets via Prony's Method and  Target Discrimination, IEEE Trans., vol. AES-12, pp. 
 Stevens: A Technique for the Generation of Highly Linear FM Pulse  Radar Signals, IEEE Tra~rs., vol. MIL-9, pp. 32-38, January, 1965. 
 BEAM CLUTTER  IS A FUNCTION NOT ONLY OF THE BASIC RADAR PARAMETERS SUCH AS POWER  ANTENNA GAIN  ETC  BUT OF RADAR ALTITUDE ABOVE THE TERRAIN AND THE RADAR CROSS SECTION 2#3  OF LOW 
  
 PULSE &)2 FILTERS AND ASSUME A PROCESS 
 Madsen, E. Rodriguez, and R. Goldstein, “Synthetic  aperture radar interferometry,” Proc. 
 It has 2688 radiating elements with a T/R module per element. Although  the active radiating aperture is approximately circular, the corners have been filled in  ch13.indd   62 12/17/07   2:41:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 W.: lnterclutter Visibility in MTI Systems, IEEE Eascon Record.  1969. pp. 
 GTD and PTD are both based on  the exact solution of the two-dimensional wedge problem, for which the directions  of incidence and scattering are perpendicular to the edge. When extended to the case  of oblique incidence, the direction of observation must lie along a generator of the  Keller cone depicted in Figure 14.19. If the edge is straight and of finite length, as  in the three-dimensional world, Eq. 
        . n°Îä  2!$!2 (!.$"//+  PRODUCT DETECTION FOLLOWED BY !$ CONVERSION IN EACH BASEBAND CHANNEL &IGURE A  SHOWS A DIGITAL IMPLEMENTATION OF A TIME 
 Walker: Recursive Methods for Computing Detection Probabilities, IEEE  Trans., vol. AES-7, pp. 671-676, July, 1971. 
 The scanning capability can be implemented  via use of either a single movable feed or an array with switchable feeds. Self-blockage (reflector blocking itself) is another potential limiting factor in spher - ical reflector systems. However, 360° of azimuth steering can be accomplished via  a polarization design scheme similar to the polarization twist subreflector described FIGURE 12. 
 J. L. Allen et al., “Phased array radar studies,” MIT Lincoln Lab. 
 This success can beviewed as demonstrating the principle that, when acomplicated task must be carried out quickly and accurately under trying conditions, extreme mechanization iswell worth while, ifitremoves from human operators the necessity foremploying judgment and forperforming complicated operations. Such mechanization substitutes fortheskill ofoperators the design, manufacturing, and maintenance skills that are necessary to 1Sections 7.1, 7.2, 7.4, 7.7, and7.8byL.N.Ridenour, Sec. 7.3byL.J.Haworth, Sec.7.5byB.V.Bowden, andSec.7.6byC.L.Zimmerman. 
 Another  ,t reason for preferring the liigller frcquetlcics in some applications, in spite of the larger clutter,  is that greater range-resolution and azimuth-resolution (shorter pulse width and narrower  beanlwidths) are easier to obtain than at lower frequencies. The higher resolution usually  results iri greater target-to-clutter ratio. Civil marine radars are available at both S band  (10 cln wavelength) and X band (3 cm). 
 The results are almost indistinguishable from those obtained bytheuseoftwo channels. TheLogarithmic Receiver.—A more involved method ofincreasing thedynamic range ofthesystem isbyuseoftheso-called “logarithmic” receiver, whose gain characteristics are such that the response varies approximately asthe logarithm ofthe input signal. One method of attaining such aresponse, which isactually anextension ofthethree-tone method, isillustrated inFig. 
 ,/"  Ê**  /" - !S HAS BEEN DEMONSTRATED  METEOROLOGICAL RADARS MEASURE BACKSCATTERED POWER AND RADIAL VELOCITY PARAMETERS 4HE CHALLENGE TO THE RADAR METEOROLOGIST IS TO TRANSLATE THESE MEASUREMENTS  THEIR SPATIAL DISTRIBUTIONS  AND THEIR TEMPORAL EVOLUTION INTO QUANTITATIVE ASSESSMENTS OF THE WEATHER 3ERAFIN AND 7ILSON   AMONG OTHERS  SHOW HOW MODERN  METEOROLOGICAL RADARS ARE USED FOR FORECASTING THE WEATHER 4HE LEVEL OF SOPHISTICATION USED IN INTERPRETATION VARIES BROADLY  RANGING FROM HUMAN INTERPRETATION OF RUDIMEN 
 Wu: "The Scattering and Diffraction of Waves." Harvard University Press,  Cambridge, Mass., 1959.  70. IEEE Standard Letter Designations for Radar-Frequency Bands. 
 386-400.  8. Welle, G. 
  
 DOPPLER TARGETS THAT ARE IN THE CLUTTER 
 the aperture and fall into the class of phase-comparison monopulse. However, the basic performance of amplitude- and phase-comparison monopulse is essen- tially the same.3 Figure 18.17 shows the antenna and receiver for one angular-coordinate track- ing by phase-comparison monopulse. Any phase shifts occurring in the mixer and IF amplifier stages cause a shift in the boresight of the system. 
 ANGLE CLUTTER WIND SPEED  ABOUT  KT AFTER & " $YER AND . # #URRIE Ú )%%%   . £x°ÓÈ  2!$!2 (!.$"//+  THE FACT THAT THE EXCITATION OF THE SURFACE 
 20  The characteristics of a CFA are illustrated by the Varian SFD-257, a forward-wave tube  used in the final high-power amplifier stage or the transmitter chain in the AN/MPS-36  C-band range-instrumentation tracking radar.18 The SFD-257 operates over the frequency  range 5.4 to 5.7 GHz with a peak power of 1 MW, 0.001 duty cycle, and an efficiency of over 50  percent. The tube is d-c operated in that the RF pulse turns the tube on and a control electrode  turns it off. In this radar application the pulse widths arc 0.25, 0.5, or 1.0 ,,s, but the tube can  deliver a pulse as wide as 5 µs. 
 Aircraft at  any altitude within this region can be detected, located, and tracked so as to provide a  cost-effective over-ocean air-traffic-control capability. Target height is not obtained with this  OTIl radar. (Nor is height obtained with tlie usual microwave air-traffic-control radars.) It is  possible to utilize modified H F communications equipment as transponders on each aircraft  which can relay back to the radar tlie height of the aircraft as determined by the onboard  altimeter, as well as tlie identity of the aircraft. 
 CENTERED REGION   4HE TERM COOPERATIVE TRANSMITTER IS SOMEWHAT OF A MISNOMER &OR EXAMPLE  A COOP 
 Ground Penetrating Radar (GPR), discussed in Chapter 21, is an example of what  is called an ultrawideband (UWB) radar. Its wide signal bandwidth sometimes cov - ers both the VHF and UHF bands. Such a radar’s signal bandwidth might extend,  for instance, from 50 to 500 MHz. 
 -/"  )N !-4) SYSTEMS HAVING MANY HITS PER SCAN  SCANNING IS A SECONDARY LIMITATION FOR  AN UNCOMPENSATED DOUBLE CANCELER (OWEVER  THE PERFORMANCE OF A $0#! SYSTEM IS SIGNIFICANTLY REDUCED WHEN IT IS SCANNED 4HIS IS DUE TO THE SCANNING MODULATION ON THE  DIFFERENCE PATTERN USED FOR PLATFORM 
 ANCE OF THE SEA SPIKES IS VERY SIMILAR FOR BOTH MODERATE AND WEAK WIND CONDITIONS  ALTHOUGH THE  AMPLITUDES DIFFER BY ALMOST   D"  AND THE VERTICALLY POLARIZED RETURNS  APPEAR TO BE SOMEWHAT BROADER  WHILE THE HORIZONTALLY POLARIZED RETURNS ARE MORE SPIKY  PARTICULARLY FOR SHORT PULSES IN CALM SEAS 4HESE ARE ALL CHARACTERISTICS OF SEA CLUTTER AT LOW GRAZING ANGLES 4HE PROBABILITY DISTRIBUTIONS OF LOW GRAZING ANGLE SEA CLUTTER CHANGE WITH WIND  SPEED %XAMPLES MAY BE FOUND IN THE MEASUREMENTS BY 4RIZNA OF L OW 
 Range Boxcar  gate - generotor No. n  .. .. 
 72. E. K. 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 As seen in Figure 7.28, the selection of Q(tk) and thus gtrack allows one to uniquely  determine the steady-state tracking gains as a function of gtrack. One can see that  large assumed maneuvers (large q, aa, or a); larger time between updates, T; or very  accurate radar measurements (small ℜ) will result in large tracking gains. 
 306-310  paraboloid. 226  Fences. radar, 175. 
 -...--2.2 .-...—.-.---L.f...–.l :- _.L--L__,.. _. .L:.--:- .-..-;.11.. 
 Amplifiers may be placed between the individual antenna elements and the beam-  forming (phase-shifting) networks to amplify the incoming signal and compensate for any  losses in the beam-forming networks. The output of each amplifier is subdivided in to a nurnber  of independent signals which are individually processed as if they'were from separate receivers.  Postamplification beam forming. 
 12.20. The swept oscillator must produce a linear sweep; this is easy with yttrium- iron-garnet (YIG)-tuned oscillators but requires linearizing circuits if tuning uses a varactor. If dual antennas are used (as shown), the overlap of the beams must be considered.69 Single-antenna systems are sometimes used, with a circulator isolating transmitter and receiver; their performance is somewhat poorer than that of dual-antenna systems because of internal reflections and leakage through the circulator. 
 44Scattering Mechanisms Double diffraction from sharp corners Diffraction from rounded objectSPECULAR DUCTING,  WAVEGUIDE  MODESMULTIPLE REFLECTIONS EDGE DIFFRACTIONSURFACE  WAVES CREEPING  WAVES• Scattering mechanisms are used to describe wave behavior.   Especially important at radar frequencies:specular = "mirror like" reflections that satisfy Snell's law surface waves = the body surface acts like a transmission line  diffraction = scattered waves that origin ate at abrupt discontinuities. 45Example: Dipole and Box •f =1 GHz, −100 dBm (blue) to −35 dBm (red), 0 dBm Tx power, 1 m metal cube ANTENNABOX Reflected Field  OnlyREFLECTEDIncident + Reflected Reflected + Diffracted Incident + Reflected  + Diffracted ANTENNABOX Reflected Field  OnlyREFLECTEDIncident + Reflected Reflected + Diffracted Incident + Reflected  + Diffracted. 
 22. George, S. F.: EKectiveness of Crosscorrelation Detectors, Proc. 
 CIRCLE DISTANCE AND BEARING GRID REGISTRATION  REQUIRES THAT TILT OR GRADIENT EFFECTS BE TAKEN INTO ACCOUNT 4HE DAYTIME EXAMPLE HAS LITTLE HORIZONTAL GRADIENT  AND THE SIMPLIFYING ASSUMPTION MAKES LITTLE DIFFERENCE 7HEN BETTER ACCURACY IS DESIRED  THE CORRECT VERTICAL PROFILE CAN BE USED FOR EACH RADIATION ANGLE ALSO  GRADIENTS CAN BE SIMULATED BY MAKING THE IONOSPHERE NONCONCENTRIC WITH THE %ARTH ! MORE COMPLETE PATH ANALYSIS SHOULD BE USED IN RADAR PERFORMANCE  ASSESSMENT AND MANAGEMENT  BUT THESE PLASMA DENSITY CONTOURS CAN BE USED TO  ESTIMATE THE MAGNITUDE OF THE ERRORS INTRODUCED BY THE ASSUMPTI ON OF A SPHERICALLY  SYMMETRIC IONOSPHERE &IGURE  SHOWS A PERFORMANCE PREDICTION FOR A HYPOTHETICAL RADAR IN THE FORM  OF AN OBLIQUE SOUNDING ! TYPICAL SKYWAVE RADAR IS SUPPORTED BY ONE OR MORE VERTI 
 In fact, in the latter case the useful signal is integrated while the interference is canceled. The implementation of an adaptive array has been limited to experimental sys- tems with a small number of antennas (say, 10), so that the matrix inversion can be handled by practical computing systems.44'45 Arrays with a large number of receiving elements need some form of processing reduction. One method of par- tial adaptivity is to arrange the array elements in subgroups which form the inputs of the adaptive processor. 
 BASED OR HELICOPTER SYSTEM THAT IS WELL CALIBRATED AND TO COMPARE THE IMAGES TO THESE MEASURED VALUES  &)'52%     "ASIC BLOCK DIAGRAM OF AN &- 
 W. Meadows, and P.A. Matthews: Layer Structure of the Troposphere,  !'roe. 
 Inorder toreduce hunting, astabilizing transformer (Fig. 1413) isnow used with most of thelarger alternators. Such atransformer provides acorrection depend- ingontherate ofchange ofexcitation. 
 H. S.: Characteristics of Triangular Lattice Arrays, Proc. IEEE, vol. 
 Sometimes the terms /cr·d and cross IC'l'el are used to refer to the angles in a stabilized  system. 14 The /ere/ angle is the angle between the horizontal plane and the deck plane,  measured in the vertical plane through the line of sight. The cross-level angle is the angle,  measured about the line of sight. 
 King, D. D.: The Measurement and Interpretation of Antenna Scattering, Proc. IRE, vol. 
 If the clutter cross section  is log normal, the probability density function describing its statistics is  p(oJ = -.~ · exp [----~2 ( In <le )2 ] .,/ 21[ (J(j C 2a (J' m <Jc> 0 (13.lla)  where <J, clutter cross section  a,., median value of a,  a itandard deviation of In <re (natural logarithm)  The probability density function that describes the statistics of the voltage amplitude at the  output of the envelope detector when Eq. (13.l la) is the clutter input, is given by  (13.llb)  where ,,,,, is the median value of v and u remains the standard deviation of ln <1, .114 A fit  of the Jog~normal probability density function with a = 6 dB to actual data for sea state 2  to 3 is shown in Fig. 13.5. 
 DELAY SECTIONS  AS SHOWN IN &IGURE  &)'52%  &OUR 
 The conventional definition is the angular width of the beam between the half- power points of the pattern. Pattern is used here in the usual antenna sense, for one-way transmission. It is not the two-way pattern of the radar echo signal from a stationary target as the antenna scans past it. 
 Ê- 1 / 
 Table 13.2 lists examples of the Weibull parameter  ex (in Eq. 13.12) for several types of clutter and sea state.  Land clutter models. 
 Theproblem ofsynthesizing optimum waveforms fromanambiguity diagram specified byoperational requirements isadifficultoneandisoften approached bytrialanderror. Thenameambiguity function forIX(TR,fd)12issomewhat misleading sincethisfun,::tion describes moreaboutthewaveform thanjustitsambiguity properties. Woodwardscoinedthe nametodemonstrate thatthetotalvolume underthisfunction isaconstant equalto(2E)2, independent oftheshapeofthetransmitted waveform, [Eq.(11.54)]. 
 60. Johnson, J. B.: Thermal Agitation of Electricity in Conductors, Phys. 
  
 Since the antennas generally used in pulse doppler radars have a single, relatively high- gain main beam, main-beam clutter may be the largest signal handled by the radar when  in a down-look condition. The narrow beam limits the frequency extent of this clutter  to a relatively small portion of the doppler spectrum. The remainder of the antenna pat - tern consists of sidelobes, which result in sidelobe clutter. 
 Remote Se11si11g. All radars are remote sensors; however, as this term is used it implies the  sensing of geophysical objects, or the'.' environment." For some time, radar has been used  as a remote sensor of the weather. It was also used in the past to probe the moon and the  planets (radar astronomy). 
 In general, the effective noise temperature has been preferred fgr describing  low-noise devices, and the noise figure is preferred for conventional receivers. For radar  receivers the noise figure is the more widely used term, and is what is used in this text.  18 Measurement of noise figure. 
 D. West, “ECM modeling for multitarget tracking and data association,”  in Multitarget-Multisensor Tracking: Applications and Advances , vol. III, Y . 
 SIZE DISTRI 
 F. Gabriel, Guest editor, special issue on adaptive antennas, IEEE Trans ., vol. AP-24,  September 1976. 
 The d-crestorers V.hold thesweep origin fixed regardless ofduty ratio. Two fixed and one variable sweep speeds are shown. The square- wave generator isautomatically turned offatthe proper time bythe action ofV1.The positive sawtooth isdelivered tothegrid ofV,,which isbiased beyond cutoff bysuch anamount that itstarts toamplify just asthesawtooth reaches the desired peak amplitude. 
 On the other hand. the radars cannot be placed too Pdr apart since tlie curvature  of the cart11 will limit the minimum altitude at which targets can be seen. For example. 
 If there is precipitation in thecloud then the operator can expect a detectable echo. Hail With respect to water, hail which is essentially frozen rain reﬂects radar energy less effectively than water. Therefore, in general the clutter andattenuation from hail are likely to prove less detectable than that from rain. 
 SECTIONS OF TERRAIN NEAR VERTICAL INCI 
 30.Ashmead, J.,andA.B.Pippard: TheUseofSpherical Reflectors asMicrowave Scanning Aerials,J. IEEE(London), vol.93,pt.IlIA,p.627,1946. 31.Ramsey, 1.F.,andJ.A.C.Jackson: Wide-angle Scanning Performance ofMirrorAntennas, hiarconi Rev.,vol.19,3dqtr.,pp.119-140, 1956. 
 21.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 Ground Penetrating Radar David Daniels ERA Technology 21.1 INTRODUCTION The terms ground penetrating radar (GPR), ground probing radar, subsurface radar,  or surface penetrating radar (SPR)  refer to a radar-based electromagnetic technique  designed primarily for the location of objects or interfaces buried beneath the Earth’s  surface or located within a visually opaque structure. 
 In the  transmit condition (Fig. 9.6~) power is divided equally into each waveguide by the first short-  slot hybrid junction. Both TR tubes break down and reflect the incident power out the antenna  arm as shown. 
 Anytargettotherightofcurve6maybeconsidered tobewithinthediffraction region.This illustrates whymostradarsoperating atmicrowave orUHFfrequencies arelimitedtocover­ agewithinthegeometrical lincofsight. 12.7A'n'ENUATION BYATMOSPHERIC GASES5.12.28 Theattenuation ofradarenergyinaclearatmosphere intheabsenceofprecipitation isdueto thepresence ofoxygenandwatervapor.Attenuation resultswhenaportionoftheenergy incident onthemolecules oftheseatmospheric gasesisabsorbed asheatandislost.The reduction inradarsignalpowerwhenpropagating overadistance Randback(two-way path) maybeexpressed asexp(-2exR),whereexisthe(one-way) attenuation coefficient measured in unitsof(distance) -'.Insteadofplotting ex,itismoreusualtoplottheone-way attenuation in decibels perunitdistance. Thisisequivalent toplotting thequantity 4.34ex,wheretheconstant accounts fortheconversion fromthenaturallogarithm tothebase10logarithm. 
 CESS !N ENORMOUS LITERATURE IS DEVOTED TO THE THEORY OF SURFACE SCATTER FROM THIS POINT OF VIEW  STEMMING FROM THE IMPORTANCE NOT ONLY OF RADAR SEA SCATTER  BUT ALSO RADAR GROUND SCATTER AND SONAR  REVERBERATION THE ACOUSTIC EQUIVALENT OF RADAR CLUTTER   FROM BOTH THE SURFACE AND THE BOTTOM OF THE SEA "ECAUSE THE '"60 APPROACH LEADS TO THE ANALYTICAL EXPRESSION OF THE "RAGG SCATTERING HYPOTHESIS THAT HAS DOMINATED THE THEORY OF SEA SCATTER SINCE THE LATE S  A BRIEF EXPLANATION OF SOME OF THE CENTRAL IDEAS IS INCLUDED BELOW 4HEORIES "ASED ON 'LOBAL "OUNDARY 
 The ratio of the  actual boresight velocity to the coplanar boresight velocity is defined as the normal - ized boresight-velocity ratio:  VBR = =cos coscosα ψφ0 00  (3.2) where f0 is the depression angle of the antenna centerline from the horizontal. Figure 3.5  shows the variation of the normalized boresight-velocity ratio as a function of slant range  for a curved earth and different aircraft altitudes. The variation is fairly rapid for slant  ranges less than 15 nmi. 
 Magellan: Innovative Venus Mapper.  Magellan (Figure 18.15) had to face up  to two driving mission restraints: cost and data rate. The first was set by NASA and the  U.S. 
 The radialcoordinate canalsobespecified bythereflection coefficientroftheloadsincethe VSWRpandreflection coefficient arerelatedbytheequationIrI=(p-1)j(p+1).The centeroftheSmithchart(Riekediagram) corresponds tounityVSWR,orzeroreflection coefficient. Thecircumference ofthechartcorresponds toinfiniteVSWR,orunityreflection coefficient. Thustheregionoflowstanding-wave ratioistowardthecenterofthechart.. 
 53. Ward, H. R., and W. 
 Since these devices exhibit this narrow operating range,  small decreases in the input RF drive level to a multistage amplifier may bring the  final tier of devices out of saturation. Failure to control these conditions accurately  can result in unacceptably degraded output pulse fidelity. In a very simple sense, the design of an amplifier module consists of matching the  power transistors to the proper impedance level and then combining the power levels  at these impedances. 
 ECHO THEORY  4HE PAIRED 
 L. Rubin, Radar Detection,  Norwood, MA: Artech House, Inc., 1980. 69. 
 Noradar system iscomplete until adequate provisions forperformance testing and maintenance have been made and appropriate maintenance procedures prescribed. The most important function oftest equipment inradar maintenance istopermit quantitative measurement ofthose properties ofthesystem which affect itsrange performance. Experience has shown that itis essential todetermine byreliable quantitative methods how well aradar is operating. 
 CHAPTER  FOUR  MTI AND PULSE DOPPLER RADAR  4.1 INTRODUCTION  The doppler frequency shift [Eq. (3.2)] produced by a moving target may be used in a pulse  radar. just as in the CW radar discussed in Chap. 
 1.2 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 airport-surveillance radars. Its wavelength might be about 10 cm (rounding off, for  simplicity). With the proper antenna such a radar might detect aircraft out to ranges‡  of 50 to 60 nmi, more or less. 
 Metcalf shows strong evidence that the region penetrated by the aircraft, while appearing to be free of echo, had actually been obliterated because of severe attenuation. Severe storms can also produce very strong absorption at 5-cm wavelength, as noted by Allen et al.16 In some meteorological radar applications, it is desirable to attempt to mea- sure attenuation along selected propagation paths. This is done because absorp- tion is related to liquid-water content and can provide useful information for the detection of such phenomena as hail, in accordance with the dual-wavelength technique described by Eccles and Atlas.17 In the following subsections, quantitative expressions relating attenuation to precipitation are given. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 phasing for which the couplings from many elements will add in-phase to cause a large  reflection in a typical element. Consider an array in which the velocity of the surface wave is that of free space. 
 12.1. Inaddition tothescreen, these consist ofahot-cathode electron source, a“control grid” whose potential deter- mines thebeam intensity, and amechanism fordeflecting thebeam. In theexample illustrated, the deflection mechanism consists oftwo orthog- onal pairs ofparallel plates between which the beam must pass, the deflection due toeach pair being proportional tothe potential across it. 
 New York. 1970.  51. 
 These effects are discussed below.  Amplitude fluctuations. A complex target such as an aircraft or a ship may be considered as a  number of independent scattering elements. 
 Defense Science Board, Future DoD Airborne High-Frequency Radar Needs/Resources,  Office of the Under Secretary of Defense for Acquisition and Technology, Washington, DC,  April 2001. 13. M. 
 WAVE  CIRCUIT IS USED  IT IS CALLED A  GYRO 
 Jitter is usually dependent primarily on a single stage and is therefore usually not budgeted among stages. RF Leakage. A typical amplifier chain may have 90 dB of gain at the trans- mitter frequency in one shielded room or one location. 
 Neyman-Pearson observer. The threshold level was selected in Chap. 2 so as not to exceed a  specified false-alarm probability; that is, the probability of detection was maximized for a fixed  probability of false alarm. 
 I.: Tlie Band Retween Microwave and Infrared Regions, Proc. IRE. vol. 
 RANGE DIMENSION CAN BE OBTAINED BY EMPLOYING THE DOPPLER FREQUENCY DOMAIN  BASED ON 3!2 SYNTHETIC APERTURE RADAR  OR )3!2 INVERSE SYNTHETIC APERTURE RADAR SYSTEMS   AS DISCUSSED IN #HAPTER  4HERE NEEDS TO BE RELATIVE MOTION BETWEEN THE TARGET AND THE RADAR IN ORDER TO OBTAIN THE CROSS 
 Anaircraftwouldbeflownona radialcourseandoneachscanoftheantenna itwouldberecorded whetherornotatargetblip hadbeendetected ontheradardisplay.Thiswasrepeated manytimesuntilsufficient datawas obtained tocomputc. asafunctigllQ[r1!.llge, theratiooftheaverage num~erofscansthetarget wasseenataparticular range(blips)tothetotalnumber oftimesitcouldhavebeenseen (scans).Thisistheblip-scan ratioandistheprobability ofdetecting atargetataparticuJar range.altitude, andaspect.Thehead-on andtail-onarethetwoeasiestaspectstoprovide in fieldmeasurements. Theexperimentally foundblip-scan ratiocurvesaresubjecttomany limitations, butitrepresents oneofthefewmethods forevaluating theperformance ofan actualradarequipment againstrealtargetsundersomewhat controlled conditions.. 
 Deception jammers have a number of specific characteristics that can be used by  radars to identify their presence. The most prominent is that false-target returns must  usually follow the return from the jammer-carrying target and must all lie in the same  direction within a radar PRI. If the deception jammer uses a delay that is greater than  a PRI period to generate an anticipatory false-target return, then pulse-to-pulse PRI  jitter identifies the false-target returns. 
 It is a good technique  OTHER RADAR TOPICS543 Monopulse. Anelevation anglemeasurement canbemadesimilartothatofthemonopulse radardescribed inSec.5.4.Twofanbeamsarcdisplaced ("squinted ")inelevation angleand thesumanddifference patterns areobtained. Themeasurement ofangleissimilartothatofan amplitude-comparison monopulse tracking radarexceptthatitismadeopenloop;i.e..the outputvoltage fromtheangle-error detector iscalibrated toreadelevation angle.Two displaced hornswithcombining circuitry. 
 H.: Helix Frequency Scanning Feed, Microwaoe J., vol. 8, pp. 39-44, December. 
 2.22, bandwidths of1to4Me/see arecommon. The narrowest r-fcomponent, ahigh-Q TR switch, isso much wider than this that, once adjusted, nodrifts large enough tocause serious detuning are likely tooccur over aperiod ofaday orso. The problem ofkeeping aradar intune, then, consists essentially inmaintain- ing the difference between the magnetron frequency and the local- oscillator frequency constant and equal tothe intermediate frequency, with anaccuracy of1Me/see orbetter. 
 CHANGING IONOSPHERE 4HIS CHAPTER SETS OUT TO EXPLAIN THE PRINCIPAL FEATURES OF (& SKYWAVE RADAR AS IT IS  PRESENTLY IMPLEMENTED  EMPHASIZING THE PHYSICAL CONSIDERATIONS THAT GOVERN SYSTEM DESIGN AND PERFORMANCE Óä°ÓÊ / 
 However, if one does this, the homogeneity assumption (i.e., all the reference cells are sta- tistically similar) might be violated. A good rule of thumb is to use enough refer- ence cells so that the CFAR loss is below 1 dB and at the same time not let the reference cells extend beyond 1 nmi on either side of the test cell. For a particular radar this might not be feasible. 
 and S. S. Allwood: "Radio Wave Propagation," Academic Press. 
 4.Bayma, R.W.,andP.A.Mcinnes: Aperture SizeandAmbiguity Constraints foraSynthetic Aperture Radar,IEEE1975International RadarConference, pp.499-504, IEEEPublication 75CHO 93~-1 AES.(Alsoavailable inref.1.) 5.Cutrona, L.J.:Optical Computing Techniques, IEEESpectrum, vol.I,pp.101-IO!i, Octobt:r, 1964. 6.Kirk,J.c.,Jr.:ADiscussion ofDigitalProcessing inSynthetic Aperture Radar,/EEETrw/s., pp.326-337, May,1975.(Alsoavailable inref.1.) 7.Leith,E.N.:Optical Processing Techniques forSimultaneous PulseCompression andBeamSharp­ ening,IEEETrans.,vol.AES-4,pp.878-885, November, 1968.(Alsoavailable inref.1.) 8.Raney,R.K.:Synthetic Aperture Imaging RadarandMoving Targets, /EEETnHls.,vol.AES-7, pp.499-505, May,1971.(Alsoavailable inref.1.) 9.vandeLindt,W.J.:DigitalTechniques forGenerating Synthctic Apcrture RadarImages, /BMJOllr. ofResearch andDevelopment, vol.21,no.5,pp.4t5-432, September, 1977. 
 20.Holland, M.G.,andL.T.Claiborne: Practical SurfaceAcoustic WaveDevices. Proc.IEEE,vol.62, pp.582-611, May,1974. 2\.Maines.J.D..andE.G.S.Paige:Surface-Acoustic-Wave DevicesforSignalProcessing Applications. 
 An HF radar must be designed to accommodate such clutter levels even though they will not exist all the time or at any one time over all areas, es- pecially at the lower operating frequencies. NORMALIZED DOPPLER (fd/\/~g7*tt FIG. 24.3 The nominal maximum values of the seascattering coefficient are given as a function of doppler frequency for a coherent processing time of 51 s. 
 Beam scan mode analysis and design for geosynchronous SAR. Sci. China (Inf. 
 Multiple sets ofindices with different scale factors ran be. SEC. 73] AIDS TO PLOTTING AND CONTROL 219 conveniently provided byruling each individual setonathin transparent sheet. 
 (a)Search antenna pattern. (b) Homing antenna pattern. results from improper installation ortrimming ofantennas, hasthesame operational effect ascrabbing ofthe aircraft inacross-wind; ineither case, theoperator notices that therelative signal strength oftheleft and right echoes changes when the aircraft issteady onacompass course initially chosen togive equal signals. 
 The doppler component con­ t.1i11ed in the amplitude fluctuations may also be detected by applying the output of the  amplitude detector to an A-scope. Amplitude fluctuations due to doppler produce a butterfly  modulation similar to that in Fig. 4.3, but in this case, they ride on top of the clutter echoes. 
 The two adjacent antenna feeds are connected to the  two arms of a hybrid junction such as a .. magic T," a" rat race," or a short-slot coupler. The  sum and difference signals appear at the two other arms of the hybrid. 
 TATIVE ANALYSIS  OF POLARIMETRIC 3!2 DATA 7HEN IN COMBINATION WITH INTERFEROMETRIC  DATA  THE FIELD IS KNOWN AS 0OL)N3!2  FOR WHICH DEDICATED SPECIALIST MEETINGS ARE  CONVENED FREQUENTLY !N IMPORTANT METHODOLOGY IS TARGET DECOMPOSITION  THROUGH  WHICH SPECIFIC BACKSCATTER CLASSES SUCH AS DOUBLE 
 S=A.tileindexofrefraction isequalto0.866.Thecloserthespacing, thelesswillbe theindexofrefraction andthethinnerwillbethelens.However, thespacing, andtherefore the indexorrefraction. cannot bemadearbitrarily smallsincethereflection fromtheinterface bctween theIcnsandairwillincrease justasinthecaseofthesolid-dielectric lenses.Fora valueors=,1./2.theilldexorrefraction iszeroandthewaveguide isbeyondcutoffThewave incident onthelenswillbecompletely reflected. Inpractice, acompromise valueoftTbetween 0.5and0.6isoftenselected. 
 84. Bhagavan. B. 
 Albersheim, W. J.: Elevation Tracking Through Clutter Fences, S11pplemelll to I £EE Trw1s .• vol.  AES-3, pp. 
 50. B. G. 
 In the optically clear, lower atmo - spheric boundary layer, “clear air” Z values of the order –20 dB Z to 20 dB Z are typical  and frequently originate from insects and birds.35,36 In rain Z may range from about   0–10 dB Z to as much as 60 dB Z, with a 55 to 60 dB Z rain being of the type that can  cause severe flooding. Severe hailstorms may produce Z values higher than 70 dB Z.  Many operational radar types are designed to detect those Z values that produce mea - surable precipitation (0 to 60 dB Z) and “clear air” echoes to 100 km where the Earth’s  curvature prevents surface-based measurements. 
 The optimal values for log-normal interference were  calculated by Schleher19 and are M = 3, 8, and 25 for N = 3, 10, and 30, respectively. Batch Processor . The batch processor (Figure 7.3 e) is very useful when a large  number of pulses are within the 3-dB beamwidth. 
 It is not sufficient that only the first stage of a low-noise receiver have a small noise figure. The  succeeding stage must also have a small noise figure, or else the gain of the first stage must be  high enough to swamp the noise of the succeeding stage. If the first network is not an amplifier  but is a network with loss (as in a crystal mixer), the gain G 1 should be interpreted as a number  less than unity. 
 The dynamic range (peak signal to rms noise) is limited to about  20 dB for a PPI display. A key distinction, sometimes lost in the complexities of the systems that follow, is  that an MTI radar system eliminates fixed clutter because the phase of signals returned  from consecutive transmitted pulses do not (appreciably) change. The fixed clutter is  removed after as few as two transmitted pulses by the subtraction process described FIGURE 2. 
 D. T. Sandwell and W. 
 IRE,  vol. 26, pp. 309-316, October, 1963. 
 The Eﬀects of Phase Errors on DEM Accuracy With reference to Equations (25), (26) and (28), we can derive the relationship between DEM accuracyσhand the above two types of phase error: σh=λRsp 4πΔz⎭parenleftBig⎭vextendsingle⎭vextendsingle⎭vextendsingleσps⎭vextendsingle⎭vextendsingle⎭vextendsingle+⎭vextendsingle⎭vextendsingle⎭vextendsingleσpd⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭parenrightBig (34) According to Equation (34), Figures 13and 15,t h e h–σhcurve can be obtained, as shown in Figure 16. 144. Sensors 2019 ,19, 2921 Figure 16. 
 Direction finder, reconnaissance  and surveillance D. Pilotless carrier S. Special or  combinationG. 
 § ©¨¶ ¸· 
 Even so, the pulse-doppler radar has an advantaee over the CW  radar in that the detection performance is not limited by transmitter leakage or by signals  reflected from nearby clutter or from the radome. The pulse-doppler radar avoids this  difficulty since its receiver is turned off during transmission, whereas the CW radar receiver 1s  always on. On the other hand, the detection capability of the pulse-doppler radar is rcd~~~cd  because of the blind spots in range resulting from the high prf. 
 The  130 kW outputs of the two 56:1 combiners were combined in a single 2:1 isolated  hybrid that was manufactured by using a coaxial transmission line. The advertised  losses of the 2:1 and 56:1 combiners were 0.1 dB and 0.25 dB, respectively . RAMP (L-Band Air Traffic Control Transmitter). 
 1352.- 1356, November, 1954.  27. Andreasen. 
 SION LIKE #2)   WHEREAS 3,# COMBATS THE CONTINUOUS .,) !S PREVIOUSLY STATED  BOTH  TECHNIQUES COMBAT THE INTERFERENCES IMPINGING ON THE MAIN ANTENNA SIDELOBES 4HE TWO TECHNIQUES CAN BE JOINTLY USED AGAINST THE SIMULTANEOUS PRESENCE OF #2) AND .,) !N APPROACH IS TO CASCADE  THE 3,# AND 3,"  TECHNIQUES AS SHOWN I N &IGURE  4HE  SCHEME DEPICTS THREE RECEIVING CHANNELS  EACH ONE HAVING AN ANTENNA  A RECEIVER  AND AN !$# THEY PROVIDE THREE SIGNALS LABELED  RESPECTIVELY  AS  3,#  -!).  AND  3,"  4HE LEFT 
 The graph  is normalized to radar beamwidth on both axes for convenient use with a wide vari - ety of radars. The dashed portions of the curves are regions of uncertainty because  of significant variations of reflection for a given sea state. In the intermediate region, the error increases to a peak at target elevations of  about 0.3 beamwidth. 
 TERISTICS OVER TIME AND SPACE  WHEREAS OTHERS HAVE A RANDOM POLARIZATION 4HIS OCCURS  AS  FOR SUNLIGHT  WHEN THE POLARIZATION ELLIPSE CHANGES ITS PROPERTIES RANDOMLY AND RAPIDLY WITH TIME OR WITH SMALL DIFFERENCES IN ANGLE 7HEN BOTH THE PERSISTENT AND RANDOM PARTS  &)'52%     -EASUREMENT 
 RANGE DETECTION OF BALLISTIC MISSILES  THE RADAR  WILL MOST LIKELY HAVE SUFFICIENT POWER TO DETECT OTHER TARGETS ! CLUSTER OF MULTIPLE SIMUL 
 ANE-1, no. 2, pp. 3-7, June, 1954. 
 Since all de-operated CFAs use cold cathodes, no current can flow until RF drive is applied. With linear-beam tubes, beam current must be well enough cut off to keep noise output (and amplified input signals) small enough. Despite the nearly 200 dB between typical RF peak power output and typical receiver noise levels, most RF tubes readily meet the interpulse-noise requirements. 
 TRACK POSITION OF THE MINIMUM 
 Wide-angle SAR imaging. Proc. SPIE 2004 ,5427 , 164–175. 
 When a shaped beam is desired in a surveillance radar, such as a cosecant-squared  pattern, again it is more important to achieve the overall pattern required rather than simply  max'imize the directivity at the peak of the beam.  Aperture efficiency is a measure of the radiation intensity only at the center of the beam.  In a search radar, however, the radiation intensity throughout the entire beam is of interest,  not just that at the beam center. 
 PENDENT -ONTE #ARLO SIMULATIONS 4HE TARGET 3.2 IS  D" THE *.2 IS  D" THE TARGET $O! IS ASSUMED TO BE EVENLY DISTRIBUTED IN THE MAIN 
 Figure 10. Maps show subsidence rate in Region 1 ( a), and a subsidence proﬁle passing through stations A and B ( b). Wuhan city’s urban construction has entered into a stage of rapid growth during our study period 2015 −2018. 
 A line source such as a linear array, rather than a point source, must  be used to feed the parabolic cylinder. The beam width in the plane containing the linear feed is  Parabolic  surface ,.  Vertex 1-----------"----+----­ or  apex _.,,,,,.-· Focus 1  --------~  I  I  I Beam axis  Figure 7.6 Parabolic-reflector antenna. 
 A.: Computer Control of Array Radar, Sperrr Enqineeriny Reriew. vol. 18, No. 
 ) The usefulness ofbeacons was demonstrated with theearly radar sets that were operated atlong wavelengths. Alarge proportion ofthe beacons used inthe war operated atfrequencies about 200 Me/see. These included the beacons used with ASV Mark IIsearch radar, the transponders used foridentification, the portable Eureka beacons that were part ofthe independent Rebecca-Eureka beacon system, and a much-used system for precise bombing, the Oboe Mark I.Another system forprecise bombing, the Gee-H system, used beacons ofeven lower frequency. 
 fa 1slfa+fc2d(aL¢ mixer mixer Delay TfcL¢ fcFigure8.19Schematic representation oftheHuggins phaseshifter. Fixed fo fo+fefrequency Mixer Delayline oscillator fe Variable fefrequency oscillator Figure8.20Huggins phaseshift­ ingappliedtoalineararrayfeed.. I 11E lil.FC1 RONI('AI.1.Y SFFERED t'llASED ARRAY ANTENNA IN RADAR 305  line, as illustrated in Fig. 
 The entropies and IC values convergence of two sub-images versus the number of iterations. (a) Entropies change of the two sub-images during iteration; ( b) IC values change of the two sub-images during iteration.      (a) (b) (c)  Figure 19. 
 #&!2  PROCESSOR FOLLOWING THE -4) FILTER WILL USUALLY PROVIDE GOOD SUPPRESSION OF THE CLUTTER RESIDUES 3PECIAL FEATURES ARE SOMETIMES ADDED TO THE #! 
 - 7HEREAS PHASED ARRAY ANTENNAS ARE FREQUENTLY CHOSEN FOR RADAR SYSTEM DESIGNS  REFLEC 
 The swath Sw is often much smaller than the  maximum range so that the prf can be increased to allow the umambiguous range Ru to  encompass ft1e distance S,.. cos 1/1. where 1/1 is the grazing angle. 
 SWATH 3CAN3!2 IMAGERY 4HE DIRECTION OF FLIGHT IS VERTICAL IN THIS PRESENTATION  NEAR 
 587–588, 2006. 55. D. 
 . Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 111         Figure 11.18  Exam ple for the optimization of the shape.     The requirements, which are similar to those of good aerodynamics, were particularly realized  with reconnaissance airplanes. 
 OE-Il, April 1986. 7. Kolosov, A. 
 TO 
 SEC. 13.9] ELECTRONIC SWITCHES 505 input ofthecircuit, thetime elapsing before anoutput signal appears is proportional tothebias applied tothediode, thus providing anaccurate and easily controllable time delay (see Sec. 13.12). 
 (1)will beused only forthe relationships itestablishes among thesystem parameters. 15-5. Choice ofPulse Length.-The pulse length isconvenient for first consideration since itsrelations with the other parameters are relatively simple. 
 2 was the average value of the power over the duration of a pulse of  sine wave. The ratio R , is twice the average signal-to-noise power ratio when the input signal  s(t) is a rectangular sine-wave pulse.] The output voltage of a filter with frequency-response  function H( f) is  where S(f) is the Fourier transform of the input (received) signal. The mean output noise  power is  where No is the input noise power per unit bandwidth. 
 cc £  #OMB OPERATOR COMB& N8F 8N & F N &;  =    
 B. Colegrove and J. K. 
 Figure 16.1 lib shows a method of correcting for the phase advance -n. An ide- alized correction signal Ec is applied, leading the received signal by 90° and lag- ging the next received signal by 90°. For exact compensation the following rela- tion would hold: 2^7; sin 0Ec = E1 tan -q = 22(0) tan (16.9)A This assumes a two-lobe antenna pattern similar to that in a monopulse tracking radar. 
 TICS OF THE WEATHER TARGETS    4RANSMITTING THE TWO ORTHOGONAL POLARIZATIONS EITHER  SIMULTANEOUSLY 3(6  OR TRANSMITTING THEM SEPARATELY IN A PREDETERMINED SEQUENCE AND USING DUAL PARALLEL DIGITAL RECEIVERS ONE ON EACH POLARIZATION CHANNEL  ALLOW ESTI 
 Thetransistor amplifier canbeappliedovermostoftheentirerangeoffrequencies ofinter­ esttoradar.,o.'9.2o Thesiliconbipolar-transistor hasbeenusedatthelowerradarfrequencies (helowLhand)andthegaliumarsenide field-elTect transistor (GaAsFET)ispreferred atthe 60 CD "0<'10 ~ ::>0' <1J30-- 1/1 <5z 20 10- 5000 10,000 Frequency -MHz30,000 Figure9.4Noisefiguresoftypicalmicrowave receiverfront-ends asafunctionoffrequency-. higher frequencies. The transistor is generally used in a multistage config~~ration with a  typical gain per stage decreasing from 12 dB at VHF to 6 dB at K, band." In the GaAs FET,  the thermal noise contribution is greater than the shot noise. 
 G. Morris, Airborne Pulse Doppler Radar , Norwood, MA: Artech House, 1988. 66. 
 Technol ., vol. 24, pp. 791–805, 2007. 
 SCAN USING  -(Z CENTER FREQUENCY #OURTESY )%%              
 Theuniquecharacteristics ofanarrayantenna offertheradarsystems designer capabili­ tiesnotavailable withothertechniques. Aswithanyotherdevice,thearraywillseemajor application whenitcanperform someradarfunction cheaper thananyotherantenna typeor whenitcandosomething nOlpractical byothermeans. REFERENCES I.Southworth, G.c.:"Forty YearsofRadioResearch," Gordon andBreach. 
 87, pp. 717–737, May 1999. 25. 
 Turner “An ‘entraining plume’ model of a spilling breaker,”   J. Fluid Mech ., vol. 63, pp. 
 78. P. Vincent, N. 
 and J.W.; Resources, Y.L. (Yanfang Liu); Data Curation, M.J., Y.L. (Yanfang Liu) and J.W.; Writing—Original Draft Preparation, Y.Z.; Writing—Review & Editing, Y.J., Y.L. 
 ALARM 
 5.11 abalanced one — ---ml FIG. 5.13.—The AN/APN-l frequency-modulated radar altimeter, (Reprinted from Electronic-s.) (see Vol. 24) with the result that, ifthe balance isgood, amplitude modulation from the transmitter balances out inthe detector output. 
 Note that for a rectan - gular pulse, Pt is either zero or the peak transmitter power; but for other pulse shapes,  the variation with t (or R) is significant. Actual pulses are often approximated by  rectangular pulses with widths equal to their half-power widths. Real pulses cannot be  rectangular after passing through real transmitter, antenna, and receiver bandwidths. 
 CLEAR DETECTION REQUIREMENTS FOR SUCH RADARS ARE  NOT PARTICULARLY DEMANDING !N  PROBABILITY OF DETECTION AND A PROBABILITY OF FALSE  ALARM OF n IS SPECIFIED BY )-/  AS SHOWN IN 4ABLE  4AKING INTO ACCOUNT ALL PERFORMANCE REQUIREMENTS  TYPICAL COMPLIANT SYSTEMS FOR  COMMERCIAL VESSELS HAVE PEAK TRANSMIT POWERS OF  n  K7  THE LOWER POWERS BEING CONFINED TO  '(Z SYSTEMS !NTENNA GAINS FROM  TO  D" ARE TYPICAL  WITH ASSOCI 
 ,*, 
 MS DELAY  ARE THE NOISE POWERS IN DECIBELS BELOW  7(Z &OR THIS PLOT  THE 54# TIME IS   33.      0 AV    K7   'T'R    D"  4    S  AND  R    D"SM &IGURE   GIVES THE CORRESPONDING NIGHT PLOT 4HE SHAPE OF THESE DISPLAYS IS QUITE SIMILAR TO WHAT WOULD BE SEEN WITH A DIAGNOSTIC  OBLIQUE SOUNDING THE LEVELS WOULD GENERALLY BE GREATER BECAUSE THE RESOLUTION CELL AREA TIMES THE SURFACE SCATTERING COEFFICIENT IS GENERALLY MUCH LARGER THAN  D"SM 3OME  OF THE NIGHT 
 The outputs of the two feeds are combined  using a hybrid junction to produce a sum pattern C and a difference pattern A. By taking  C Ifl jkA, the effective phase center can be shifted depending on the value of k. (The factor j  multiplying the difference pattern signifies a 90" phase shift added to the difference signal  relative to the sum signal.) The use of this technique in an AMTI radar to compensate for the  effects of platform motion is called DPCA, which stands for Displaced Phase Center Anter~nn. 
 As a result, the calculated tracking accuracy is (at  least to third order) uncontaminated (or “unscented”) by the nonlinearity . Adapting Filter to Deal with Changes in Target Motion.  The Kalman filter  assumes linear target motion perturbed by a random maneuver model as a mathemati - cal convenience in calculating tracking gains. 
 Kilowatts of CW power can be obtained in the vicinity of  I-rnnl wavelength and several tens of kilowatts at 3-mm wa~elength.~~ Over a megawatt of  pulse power is clairiled at 3-~nrn wavelength. Millimeter-wave gyrotrolls require extremely  high voltages (the electrons travel at relativistic velocities) and superconducting magnets.  Receivers with mixer front-ends using Schottky-barrier diodes at room temperature have  den~onstrhted respectable noise figures. 
 For example, the database cannot contain  the height of wires strung between towers or structures erected since the database was  prepared. For the lowest possible flight profiles with less than 10–6 probability of crash  per mission, the prestored data is merged and verified with active radar measurements.  Low crash probabilities may also require some hardware and software redundancy. 
 (1), but theperformance figure remains ofvital importance in determining what fraction ofthe maximum radar range canberealized byagiven system against agiven type oftarget, regardless ofthe existing propagation conditions. TheInadequacy ofGuessing Per- formance.—It hasoften been wrongly assumed that over-all radar perform- ance can beadequately judged with- out using test equipment bymeans ofone ofthe following “rule-of- thumb” criteria: (1) the general appearance ofthe picture seen on the radar indicator, (2)the maxi-oo- Dechisbelowratedperformance FIG. 15.1.—Relation between radar performance deficit and available radar range for various types oftarget. 
 Mitchell et al.52 describe basic performance  limitations of the AN/FPQ-6 high precision tracking radar measured under ideal Component Bias Noise Radar-dependent    tracking errors    (deviation of antenna    from target)Boresight axis collimation Axis shift with    RF and IF tuning    Receiver phase shift    Target amplitude    Temperature   Wind force   Antenna unbalance Servo unbalance Receiver thermal noise    Multipath (elevation only)    Wind gusts    Servo electrical noise    Servo mechanical noise Radar-dependent    translation errors    (errors in converting    antenna position to    angular coordinates)Leveling of pedestal North    alignment Static flexure of pedestal    and antenna Orthogonality of axes solar    heatingDynamic deflection of pedestal    and antenna Bearing wobble Data gear nonlinearity    and backlash Data takeoff nonlinearity    and granularity Target-dependent    tracking errorsDynamic lag Glint   Dynamic lag variation Scintillation Beacon modulation Propagation errors Average refraction of    troposphere Average refraction of    ionosphereIrregularities in tropospheric    refraction Irregularities in ionospheric    refraction Apparent or    instrumentation errors    (for optical reference)Telescope or reference    instrument stability Film emulsion and base    stability Optical parallaxTelescope, camera, or reference    instrument vibration Film-transport jitter Reading error Granularity error Variation in optical parallax * From D. K. Barton in “Modern Radar,” R. 
 J. McLaughlin, E. Boltniew, Y . 
 VERTER FOR DISPLAY ON A 00) 4HE DIGITAL SIGNAL MAY ALSO BE SENT TO AUTOMATIC TARGET DETECTION CIRCUITRY 4HE DYNAMIC RANGE PEAK SIGNAL TO RMS NOISE  IS LIMITED TO ABOUT  D" FOR A 00) DISPLAY ! KEY DISTINCTION  SOMETIMES LOST IN THE COMPLEXITIES OF THE SYSTEMS THAT FOLLOW  IS  THAT AN -4) RADAR SYSTEM ELIMINATES FIXED CLUTTER BECAUSE THE PHASE OF SIGNALS RETURNED FROM CONSECUTIVE TRANSMITTED PULSES DO NOT APPRECIABLY  CHANGE 4HE FIXED CLUTTER IS REMOVED AFTER AS FEW AS TWO TRANSMITTED PULSES BY THE SUBTRACTION PROCESS DESCRIBED &)'52%    "IPOLAR VIDEO RETURN FROM SINGLE TRANSMITTER PULSE      &)'52%   "IPOLAR VIDEO FROM CONSECUTIVE TRANSMITTED PULSES . 
 INGS  OIL FILLING  OR ENCAPSULATION #OMPARED WITH A HIGH 
 November, 1960. 276 INTRODUCTION TO RADAR SYSTEMS  83. van der Maas, G. 
   C O S  
 Inaspeechdelivered beforetheInstitute ofRadio Engineers, hesaid:3 AswasfirstshownbyHertz,electricwavescanbecompletely reflected byconducting bodies.In someofinytestsJhavenoticedtheeffectsofreflection anddetection ofthesewavesbymetallic objectsmilesaway. It~eemstomethatitshouldbepossibletodesignapparatus bymeansofwhichashipcould. THE NATURE OF RADAR 9  radiate or project a divergent beam of these rays in any desired direction, which rays, if coming  across a metallic object, such as another steamer or ship, would be reflected back to a receiver screened  from the local transmitter on the sending ship, and thereby, immediately reveal the presence and  bearing of the other ship in fog or thick weather. 
 Lewis, F. F. Kretschmer, and W. 
 Theenergyscattered inthedirection oftheradarisof primeinterest. Therelative phasesandamplitudes oftheechosignalsfromtheindividual scattering objectsasmeasured attheradarreceiver determine thetotalcrosssection.The phasesandamplitudes oftheindividual signalsmightaddtogivealargetotalcrosssection,or therelationships withoneanothermightresultintotalcancellation. Ingeneral, thebehavior is somewhere b~tween totalreinforcement andtotalcancellation. 
 (Yun Lin) and Y.S. performed the experiments and analysis. Y.W. 
 TARGET NO.LOST TARGETS Ts (s) Tave (s) PM (W)POS ERR (m)VEL ERR (m/s) 1 0 1.958 0.5106 10–3 5.7985 116.8 65.26 5 1 0.6772 1.477 10–368.898 95.39 61.29 6 1 1.112 0.899 10–310.774 82.94 58.43TABLE 24.2  Simulation Results Without ECM TABLE 24.3  Simulation Results With SOJ and Without A-SOJ TARGET NO.LOST TARGETS Ts (s) Tave (s) PM (W)POS ERR (m)VEL ERR (m/s) 1 34 1.919 0.521 10–3 6.6179 127.5 71.09 5 15 0.6923 1.444 10–368.411 103 66.78 6 50 ch24.indd   47 12/19/07   6:01:11 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 3.Whether the signals areadded atradio frequency orintermediate frequency.. 636 MOVING-TARGET INDICATION [SEC. 16.4 EEl EEl1 ITransmitter TR ‘Echosignal Reference signal Locking IStabler.f oscillatortrlMixer At tITransmitter TR( Echosignal -%=LO Mixer Receiver (a) (b) FIG. 
 SHAPED SPECTRA AND SEPARATES THESE  TWO COMPONENTS OF THE DOPPLER SPECTRUM  USING DIGITAL SEARCH ALGORITHMS AND THEN REMOVES THESE CLUTTER COMPONENTS WHILE LEAV 
 SION OF (ALL AND 3HRADER THAT USING AN  - OUT OF . BINARY DETECTOR AT  THE OUTPUT OF AN  -4) FILTER WILL PRECLUDE FALSE ALARMS FROM THE CLUTTER RESIDUES CAUSED BY LIMITING &IGURE  SHOWS  IN ADDITION TO CLUTTER RESIDUE  THE RETURNS FROM A TARGET THAT WAS  SUPERIMPOSED ON THE DISTRIBUTED CLUTTER PRIOR TO THE CLUTTER 
 2. Concept of Aspect Entropy Because the scattering of a target is aspect dependent, CSAR is helpful in detecting the anisotropic scattering behavior of a target. Radar cross section (RCS) is a measure representing the scattering ability of the incident electromagnetic wave [ 16]. 
  
 ch11.indd   3 12/17/07   2:25:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 
 Skaggs, and J. Lloyd, “A global ionospheric model,” Naval Res. Lab. 
  OR HIGH 
 38. M. Cicolani, A. 
 8.4b does not have this problem.  In the parallel-fed array of Fig. 8.2, the energy to be radiated is divided between the  elements by a power splitter. 
 Manasse, R., R. Price, and R. .M. 
 Schultz, B. H. Gere, and F. 
 Moisture in the atmosphere at altitudes where the  temperature is below freezing takes the form of ice crystals, snow, or hail. As these parlicks fall  to the ground they melt and change to rain in the warmer environment of the lower altitudes.  When this occurs, there is an increase in the radar backscatter since water particles reflect  more strongly than ice. 
 FIELD POWER DENSITY OF A CURRENT ELEMENT  RADIATING INTO A LOSSLESS MATERIAL OF DIELECTRIC CONSTANT OF               
 The received echo is processed in the receiver by a compression filter. The compression filter readjusts the relative phases of the frequency components so that a narrow or compressed pulse is again produced. The pulse compression ratio is the ratio of the width of the ex- panded pulse to that of the compressed pulse. 
 Figure 12.1 illustrates  that energy radiated from the radar antenna arrives at the target via two separate paths. One is  the direct path from radar to the target; the other is the path reflected from the surface of the  earth. The echo signal reradiated by the target arrives back at the radar via the same two  paths. 
 t 13. pp. 405-412, March, 1966. 
 13.26, and broader-band operation is possible. ch13.indd   39 12/17/07   2:40:42 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 ABSORBENT MATERIAL ABOUT THE ANTENNA STRUCTURE  THE USE OF A FENCE ON GROUND INSTALLATIONS  AND THE USE OF POLARIZATION SCREENS AND REFLECTORS 4HIS MEANS THAT VERY LOW SIDELOBE ANTENNAS ARE COSTLY IN TERMS OF SIZE AND COMPLEXITY WHEN COMPARED WITH CONVENTIONAL ANTENNAS OF SIMILAR GAIN AND BEAMWIDTH CHARACTERISTICS 3ECOND  AS THE DESIGN SIDELOBES ARE PUSHED LOWER AND LOWER  A POINT IS REACHED WHERE .   %,%#42/.)# #/5.4%2 
    &)'52%  3AMPLED PHASE NOISE SPECTRUM DUE TO PHASE NOISE ALIASING  
 Transmitters are generally in the  form of high-powered, coherent transmitting tubes or solid-state amplifiers. At the  University of Kyoto, Japan, the antenna-transmitter system consists of 475 crossed  Yagi radiating elements, each with its own solid-state transmitter.185 This approach  allows for very flexible electronic scanning of the beam. NOAA operates a net - work of over thirty 404 and 449 MHz wind profilers in the central United States  using solid-state transmitters that supply continuous wind profiles up to 20 km for  improved weather forecasts and current upper air wind information for aviation  applications.186 It is important to recognize that three-beam doppler systems can accurately  measure horizontal winds in all three velocity components if the wind is uniform. 
 BORNE 3!2S  BECAUSE IT  LEADS TO AZIMUTH AMBI 
 FREE DYNAMIC RANGE 3&$2  AND 3.2 OVER CONVENTIONAL .YQUIST CONVERTERS WHERE TIGHT TOLERANCES ARE REQUIRED TO ACHIEVE VERY LOW SPURIOUS PERFORMANCE $IGITAL FILTERING AND DECIMATION IS REQUIRED TO PRODUCE DATA RATES THAT CAN BE HANDLED BY CONVENTIONAL PROCESSORS 4HIS FUNCTION IS EITHER PERFORMED AS AN INTEGRAL PART OF THE !$ CONVERTER FUNCTION OR CAN BE INTEGRATED INTO THE DIGITAL DOWNCONVERSION FUNCTION USED TO GENERATE DIGITAL )  AND 1 DATA  AS DESCRIBED IN 3ECTION  0ERFORMANCE #HARACTERISTICS  4HE PRIMARY PERFORMANCE CHARACTERISTICS OF !$  CONVERTERS ARE THE SAMPLE RATE OR USABLE BANDWIDTH AND RESOLUTION  THE RANGE OVER WHICH THE SIGNALS CAN BE ACCURATELY DIGITIZED 4HE RESOLUTION I S LIMITED BY BOTH NOISE  AND DISTORTION AND CAN BE DESCRIBED BY A VARIETY OF PARAMETERS 3AMPLE  2ATE 3AMPLING  OF  BAND 
 Not many years ago the possibility of such a  stop-watch would have been scoffed at by all serious  thinkers. In a period of about fifty years radio, as we  know it to-day, was developed; in various stages came  the valve, the pulse transmitter, the cathode-ray tube  CG  . 34 HOW RADAR WORKS  (which is now the basis of our electric stop-watch), and,  finally, the radar system, which would have been just a  piece of neat mathematics in Sir Robert Watson-Watt’s  notebook, quite undemonstrable because we had no  apparatus for measuring millionths of a second, but for  the fact that when we discovered the precious secret of  radar there was the electronic ‘stop-watch,’ ready for a  whole new series of discoveries. 
 and S. Weintraub: Tile Constants in tlie Equation for Atmospheric Refractive Index at  Radio Frequencies. Pro(*. 
 However, the  notches are significantly wider than those of the elliptic filters; thus, they will  have greater bias for measurement of weather intensity when the weather radial  velocity is zero. For phased array radars, FIR filters similar to those described for the ASR-11 are  applicable. The filters can be designed, if the time budget of the phased array radar  allows, to utilize more than the five pulses per coherent processing interval (CPI) used  by the ASR-11 radar. 
 Atmos. Ocean. Technol ., vol. 
 ITED TO THE CAPABILITY OF A SINGLE CHANNEL )N A DIGITAL BEAMFORMING SYSTEM  THERE ARE MULTIPLE RECEIVERS AND !$#S  AND THE NUMBER OF !$#S THAT ARE COMBINED DETERMINES THE SYSTEM DYNAMIC RANGE &OR EXAMPLE  IF THE OUTPUTS OF  !$#S WERE COMBINED TO FORM A BEAM  ASSUMING THAT EACH !$# INDUCES NOISE THAT IS OF EQUAL AMPLITUDE AND UNCORRELATED WITH THE OTHERS  THERE WOULD BE A  D" INCREASE IN SYSTEM DYNAMIC RANGE  COMPARED TO A SINGLE 
 however, to operate withtheantenna beampointedeitherforward oraftofbroadside. Thi':iscalledthe sqliilltmode.Thesignalprocessor mustbemodified toaccount fortheaveragedoppler fre­ quencynotbeingzero.Recorders anddisplays mustbeldesigned toaccount fort11'.'geometry oftheoffsetbeam.Compensation mightalsobenecessary for"rangewalk,.whichistheresult ofthetarget,.walking" through oneormorerange-resolution cellsduringthetimeorobserva­ tion.Theachievable cross-range. oralong-track, resolution worsens asthesquintanglein­ creasesfrombroadside (c)cr~I/sin0,where0=anglebetween aircraftheading andsquinted antenna beamdirection). 
 TER CANCELLATION  OF MODERN RADAR SYSTEMS  )N THIS CASE  TRADITIONAL STATIC MEASURES  SUCH AS DETECTION RANGE AGAINST A GIVEN TARGET WILL NO LONGER ADEQUATELY DEFINE THE CAPABILITIES OF RADAR SYSTEMS -EASURES OF RADAR DYNAMIC CHARACTERISTICS  SUCH AS THE SUSCEPTIBILITY TO PROCESSOR OVERLOAD OR THE TIME TO ADAPT IN CHANGING CONDITIONS  ARE MORE IMPORTANT -ODELING AND SIMULATIONS TO EVALUATE THE RADAR  RESPONSE TO STANDARD 
 A two-frequency MTI transmits a pair of pulses, either  simultarieously or in close sequence, at two separate carrier frequencies. The two received  signals are mixed in a nonlinear device and the difference frequency is extracted for normal  MTI signal processing.  Ttie advantage of tlle greater first blind speed obtained with the two-frequency MTI is  accorrlpanied by several disadvat~tages.~~ If the ratio of the two frequencies is r < 1, the  standard deviatiori of the clutter doppler spectrum a, for a single-frequency MTI is increased  to n,(l t r.Z)"Z it1 a two-freqi~ency MTI. 
 TO 
 Figure 12.22  Matched filter output for non -linear chirp  shown in Figure 12.21.  . Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  129          Figure 12.23  Non-linear chirp compressed output using Bessel filter and phase -only Matched  filter. 
 ( a) Traditional imaging approach, ( b) Global sparsity mixed sum norm processing; ( c) Global sparsity mixed Euclidean norm processing ( d) Global sparsity mixed inﬁnite norm processing. 4.1.1. Precision Analysis of Scattering Point Coordinate Estimation Based on the above experiments, three typical scattering points are selected for statistical comparison. 
 The transmitter-to-target-to-receiver range measured by a bistatic radar is the range  sum ( RT + RR). Methods for measuring this sum are given in Section 23.6. The range  sum locates the target somewhere on the surface of an ellipsoid whose foci are the  transmitter and receiver sites. 
 ORDER FILTERS  AND THESE ARE SOMETIMES IMPLEMENTED AS INFINITE IMPULSE RESPONSE ))2  FILTERS 4HE OUTPUT OF THE SUBTRACTORS IS AGAIN A BIPOLAR SIGNAL THAT CONTAINS MOVING TAR 
 Their approach is a combination of space-time processing (see the literature1,25,45,46,  for a discussion of Space-Time Adaptive Processing or STAP) and time-frequency  processing.47,48 Figure 17.10 a shows a simulated point-spread function (PSF) of a  moving point target after clutter cancellation, and Figure 10 b shows the final simu - lated PSF after range migration compensation. The authors state: “The [point] target is supposed moving on the terrain (shadow - ing effects have been neglected) at a constant velocity, in a direction oblique with  respect to the radar motion. The velocity parameters have been chosen in order to  make evident the presence of range migration and of cross-range smearing of the tar - get image. 
 This  type of antenna, an example of which is shown in Fig. 7.25, is widely used when ran beams are  desired.  Another means of producing either a symmetrical or an asymmetrical antenna pattern is  with the parabolic cylinder.1 · 7• 13 The parabolic cylinder is generated by moving the parabolic  contour parallel to itself. 
 l in" Microwave Scanning Antennas, vol. 111:·  R. C. 
 XXI, 1985. 17. R. 
 DOMAIN CLUTTER INPUT AND OUTPUT RESIDUE AS ANTENNA SCANS PAST   A POINT TARGET                     " "  !!       
 ARRAY ANTENNA IN A WAVEGUIDE v  )%%%  4RANS  VOL !0 
 CARRYING AIRCRAFT REQUIRES INJECTING PULSE 
 TheRaytheon QKH1763X-bandcoaxialmagnetron tunesinthismannerovera lOO-MHz rangeatratesupto200Hz.Electronic tuningisalsopossible.49 6.3KLYSTRON AMPLIFIER Theklystron amplifier isanexample ofalinearbeamtube,orO-typetube.Thecharacteristic featureofalinearbeamtubeisthattheelectrons emittedfromthecathode areformedintoa longcylindrical beamwhichreceives thefullpotential energyoftheelectricfieldbeforethe beamenterstheRFinteraction region.Transit-time effects,whichlimittheoperation of conventional grid-controlled tubesatthehigherfrequencies, areusedtogoodadvantage inthe klystron. Astheelectron beamoftheklystron passestheinputresonant cavity,thevelocityof theelectrons ismodulated bytheinputsignal.Thisvelocitymodulation ofthebeamelectrons isthenconverted todensitymodulation.- Aresonant cavityattheoutputextracts theRF powerfromthedensity-modulated beamanddeliversthepowertoausefulload.. RADAR TRANSMITTERS 201  The klystroti lias proven to be quite important for radar application. 
 (8.30). the loss of gain is found to be 1.0 dB for a two-bit phase shifter, 0.23 dB for a  three-bit phase shifter, and 0.06 dB for four bits. On the basis of the loss in gain, a three-or  four-bit phase shifter should be satisfactory for most applications. 
 13.56. Atlow signal levels the principal contribution isfrom the last stage, where the over-all gain ishighest.. 554 THERECEIVING SYSTEM-INDICATORS [SEC. 
 Often, RWS is RGHPRF with three phases in which a constant frequency and two  chirp (linear FM) frequencies (triangular up-down or up-steeper up) are used to resolve  range and doppler in a sparse target space. At low altitudes, sidelobe clutter, even   with STAP processing, limits performance for all targets but especially opening targets.   ch05.indd   20 12/17/07   1:26:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 72 INTRODUCTION TO RADAR SYSTEMS  the noise that accompanies the transmitter leakage signal rather than by any damage caused  by high power.5 For example, suppose the isolation between the transmitter and receiver were  such that 10 mW of leakage signal appeared at the receiver. If the minimum detectable signal  were 10-13 watt (100 dB below 1 mW), the transmitter noise must be at least 110 dB  (preferably 120 or 130 dB) below the transmitted carrier.  The transmitter noise of concern in doppler radar includes those noise components that  lie within the same frequency range as the doppler frequencies. 
 An advantage claimed for this hybrid tracking technique is that, like monopulse, target  amplitude fluctuations do not affect the tracking accuracy. It is also claimed that the simplicity  of conical scan is retained. Both claims can be debated. 
 Uhlenbeck: "Threshold Signals," vol. 24, M.I.T. Radiation Laboratory Series. 
 V. S. Loshchilov and V. 
 Eng., vol. 66, pp. 888-893, September, 1947. 
 Examples are drawn from the  design of TOPEX.83,84 Pulse-limited Altimeters.  Figure 18.10 illustrates the pulse-limited condition.85  The radius rP of the area delimited on a quasi-flat surface by a pulse of length t  sec- onds on the Earth of mean radius RE seen from a relative altitude of h kilometers is  r c hP R = τ α/ (18.16) where a R = (RE + h)/RE is a consequence of the spherical observation geometry. For  typical satellite radar altimeters, the pulse-limited footprint over a quasi-flat surface is  on the order of two kilometers in diameter. 
 An equivalent definition of improvement factor is / = rjr0, where rt is the input ratio of clutter to noise and r0 is the output ratio of clutter residue to noise. The use of/ is encouraged instead of older terms, such as cancellation ratio and clutter attenuation, because these terms have not been consistently used in the literature and are not always normalized to the average canceler noise gain. Signal-to-Clutter Ratio Improvement (/SCR)- For a system employing multiple doppler filters, such as the MTD, each filter will have a different improvement factor against the same clutter source. 
 TRACKING SERVO LOOP 4HE ANGLE 
 For a loss-free, isotropic antenna, the gain is unity. In free space, the power density at a loss-free, isotropic receiving antenna is the  power density over the entire sphere’s surface times the area of the sphere covered  by the receiver antenna, also called the antenna’s effective aperture, Ae. The effective  aperture is related to the wavelength ( l) of radiation by  AG e=l p2 4 (26.9) Thus, the power at the receiver, Pr , for isotropic radiating and receiving antennas  (Gt = Gr = 1) is  P P AP rr a et= =l p2 24( ) (26.10) The free-space path loss, Lfs, expressed in terms of the sphere’s radius, r, and wave - length,  l, where r and l are in the same units is  LP Prt rfs=  =   10 104 10 102 2log l og( )p l (26.11) Free-space path loss, Lfs, expressed in terms of range and frequency (in decibels)  is given by  L f rfs= + + 3245 20 20 . 
 Hence, there will be no bias error over water. A very narrow antenna beam will also reduce the  over-water bias error without the need for lobe switching. Another source of error is the mass  movement of water caused by tides, currents, and winds, which result in a doppler frequency  shift in addition to that caused by the aircraft's motion. 
 Inother words, the target appears tobeatrest when ittravels adistance x/2 (oramultiple ofh/2) between pulses, Numerically, First blind speed =Xj,/89 (Aincm, speed inmph) (16) Going back toEq. (13) weseethat theaverage canceled signal, after rectification, isgiven by M=:~olsin (~.fdT)l (17) Wehave tocompare this amplitude with that ofnoise after cancellation. The noise amplitude inthedelayed channel iscompletely independent of that intheundelayed channel. 
 Readers who pre- fer the exp (jut) time convention may replace i by -j wherever it appears. 77.2 THECONCEPTOFECHOPOWER Definition of RCS. An object exposed to an electromagnetic wave disperses incident energy in all directions. 
 ZERO WAVE SPECTRUM IS NOT CONFINED TO DIRECTIONS HAVING A COMPONENT PAR 
 This value can  be calculated by measuring the time it takes the signal to return.  The range is important since the power obtaining a reflecting  object is inversely related to the square of its range from the  radar.   Free-space path loss i s the loss in signal strength of an  electromagnetic wave that would result from a line -of-sight path  through free space, with no obstacles nearby to cause reflection  or diffraction. 
 OF 
 SECTIONAL AREA OF THE LATTER WOULD FADE INTO INSIGNIFICANCE  EVEN NOISE 4HE PERSUASIVENESS OF THE CLAIMANT AND THE LACK OF UNDERSTANDING OF BASIC PHYSICS ON THE PART OF SOME POTENTIAL USERS ENABLED THIS KIND OF CLAIM TO BE SERIOUSLY CONSIDERED #LAIMS WERE MADE THAT A '02 HAD BEEN DEVELOPED hTHAT CAN PROVIDE THREE 
 Then, before eclipse occurs, the PRF is switched to one of the other values. One of these val- ues is certain to be uneclipsed, owing to the synchronization and relative PRF values. Since tracking is carried out in true range, no transient occurs and eclipse-free tracking continues indefinitely. 
 108.Gossard. E.E.,andW.HHooke:"Waves intheAtmosphere." Elsevier Scientific Publishing Co., NewYork.1975. 109.SaxtonJA.,J.A.Lane,R.W.Meadows, andP.A.Matthews: LayerStructure oftheTroposphere. 
 The shorted-turn effect may be minimized by a waveguide made of plastic which is  coated with a thin copper plating. Sometimes a slit is cut in the side wall of the waveguide to  reduce the eddy currents. Another factor that complicates operation is hysteresis which causcs  the value of permeability to differ for increasing and decreasing current. 
  D" AT LOW  ALTITUDE  TO  ^  
 K .. anti S. M. 
 ING A CHIRP WAVEFORM THAT HAS RANGE SIDELOBES BETTER THAN  D" USING AN  r MULTIPLIER  REQUIRES THAT THE INPUT SIGNAL HAS LESS THAN  DEGREES PEAK 
 NOTCH -4) WOULD USE TWO OR THREE ZEROS &OR THE ADAPTIVE PORTION OF THE -4)  A FULLY DIGITAL IMPLEMENTATION IS SHOWN IN WHICH THE PULSE 
 6.12f)), this iscalled aspiral scan; acomplete scan takes 4sec. The display used for search isthe “double dot” indicator described inSec. 6.7 (Fig. 
 46  THE USE OF A #%! REDUCES THE REQUIRED PRIME POWER BY ONE 
 Under low SNR, the performance estimated by the heights of the four approaches is low. With the increase of SNR, height estimation performance increases. However, the estimation 166. 
 This chapter is devoted to the description of the ECCM techniques and design principles to be used in radar systems when they are subject to an ECM threat. Section 9.2 starts with a recall of the definitions pertaining to EW and ECCM. The topic of radar signals interception by EW devices is introduced in Sec. 
 If weight is an important consideration, as it would be in a space-based sys - tem, then the circulator could be replaced by diode switches requiring additional logic  and driving circuitry. 13.11 MULTIPLE SIMULTANEOUS   RECEIVE BEAMS With the proliferation of ballistic missiles, future shipboard radar systems will prob - ably need multi-mission capability, which includes both anti–air warfare (AAW) and  ballistic missile defense (BMD). The BMD requirement to discriminate small radar  cross section (RCS) re-entry vehicles (RVs) at long ranges requires that active array  radars have a large power-aperture-gain/loss-noise temperature (PAG/LT), which is a  measure of the sensitivity of the radar. 
 CON ,$-/3 &%4 AS A HIGH FREQUENCY POWER TRANSISTOR 4HE CONTINUOUS PROCESS FABRICA 
 Radarscope Interpretation Relatively large range errors can result from incorrect interpretation of a landmass image on the PPI. The difﬁculty of radarscope interpretation canbe reduced through more extensive use of height contours on charts. For reliable interpretation it is essential that the radar operating controls be adjusted properly. 
 Symp. & URSI Radio Science Meeting, San  Jose, pp. 1026- 1029, June 26- 30, 1989  − E. 
 TRACKING CIRCUITS ! PRIMARY %##- DEFENSE AGAINST 2'0/ IS THE USE OF A LEADING 
 ACTIVE ILLUMINATION AS WELL AS REFERENCE SIGNALS AND MIDCOURSE COMMAND DATA DERIVED FROM MISSILE AND TARGET TRACK 
 SORT PROCES 
 Ri17e~~ has shown that tlie approximation to the antenna pattern derived on the basis of  tlie Fourier integral for continuous antennas (or the Fourier-series method for discrete arrays)  has tlie property that the mean-square deviation between the desired and the approximate  patterns is a minimum. It is in this sense (least mean square) that the Fourier method is  optimum. The larger the aperture (or the greater the number of elements in the array), the  better will be the approximation. 
 At the  higher frequencies the backscatter from rain is greater, and the MTI blind speeds are more of a  prohlem. Because of the smaller apertures and the greater effect of rain clutter, S-band radars  arc likely to have less range capability than radars at lower frequencies. Frequencies higher  than S band are seldom used for long-range air surveillance. 
 T.3040 (E K Cole), (a) front panel, with RF output at top right and AC and DC power input at bottom left; switch S1 activated the HT supply; S2 connected the HT to the anodes of the VT.90 valves; (b) power supply section. T1, T2 and T3 are the power supply transformers, V1 and V2 are the recti ﬁer diodes and C11, C12 and C13 are power supply smoothing capacitors; the anode Lecher line and output ﬁlter are in the rear compartment [ 7].Airborne Maritime Surveillance Radar, Volume 1 2-10. 2.2.2.4 Receivers The two main types of receiver were the R.3039 series, which used acorn valves (VR95) in the RF stages, and R.3084 series, which used VR136 (RF pentode) and VR137 (RF triode for the local oscillator) valves. 
 The data can be used tocontrol ascan converter ordirectly inelectronic PP1’s or related indicators. 17.4. Methods ofCombating Interference.-Aside from providing the best possible signal-to-interference intensity ratio atthe receiver input, theprincipal method ofminimizing theeffects ofinterference isto take advantage ofdifferences between the desired and the undesired signals. 
 Since norurrent floii-s across thegap between thechoke and itsmating flange, physical contact isnotnecessary. The power flows across asmall gap with negligible loss, However, insuch acase theleakage ofradiation, although small compared tothetransmitted po\~cr, may still o~-erwhelm sensiti~-e energ~- detectors nearby. Incases ~vhere electrical leakage must beminimized and the outer gasket groove isnot needed forpressurization, anelectrical gasket issubstituted. 
 Peak output power is 800 W. Instrument mass is 24 kg and input  power 50 W. Atmospheric & Ionospheric Sounding –Flight Systems. 
 A  few are here listed:   Still Object Recognition:  Stationary objects have the same characteristics as objects on the  sides of the roads or bridges.  They are distinguished only by their history, meaning that it is  recognized somewhat late whether the objects  represent dangers or not.   Detection with vrel = 0:  With FM -CW sensor there can be problems for objects which move  very quickly, where vrel = 0, since the velocity value zero is difficult to measure. 
 Unless all the reflections are collimated back at some central point (or independent feeds are used), some of the reflected energy will generally be re-reflected and contribute to large undesirable sidelobes. For large arrays the impedance of an element located near the center of the array is often taken as typical of the impedance of every element in the array. As might be expected, this element is most strongly influenced by elements in its immediate vicinity. 
 VI by the addition of a ‘lock–follow ’system. This allowed the scanner to be stopped to point at a target, which could then be tracked in range and bearing. The tracking systemalso incorporated a blind bombing facility, which was part of the Mark III ASV bombsight. 
 BEAM TUBES CAN HAVE LONG LIFE 'ILMOUR  REPORTS  THAT THE MEAN TIME BETWEEN FAILURES -4"&  OF  DIFFERENT APPLICATIONS OF KLYS 
 48. I. M. 
 MONOSTATIC ARRANGEMENT WHERE THE . 
 The impulse response of the filter, if it is to be realizable, is not defined for t < 0. (One  cannot have any response before the impulse is applied.) Therefore we must always have  t < t 1• This is equivalent to the condition placed on the transfer function H(/) that there be a  phase shift exp ( -j2rrft 1 ). However, for the sake of convenience, the impulse response of the  matched filter is sometimes written simply as s( -t ). 
 Diesel fuel and diesel exhaust fumes areless hazardous. Electric power forloads larger than 7.5kva should be208/120-volt 3-phase 60-cycle alternating current. Itisdesirable touse 3-phase 60-cycle because electric motors ofthis rating arecompact and simple to operate. 
 The circuits shown areequally applicable toamagnetic tube, the only appreciable changes being inthedeflection amplifiers. The timer ofFig. 121 can beused intheproduction ofmany other types ofindication. 
 Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 8.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 The frequency modulation-versus-time function for a tangent-based waveform is  given as  f t B t T T t T ( ) tan( )/( tan) = − ≤ ≤ 2 2 2 2 β β for  (8.16) where T is the pulsewidth, B is the swept bandwidth, and b  is defined as   β α α = ≤ < ∞−tan ( ),10   where a  is a time sidelobe level control factor. When a  is zero, the tangent-based NLFM waveform reduces to an LFM wave - form. 
 In tlie limit of large 0, and small 00, the loss approaches a maximum of  3 dB.  Shaped beams and S'I'C. A radar that can detect a 1 m2 target at 200 nmi can detect a loe4 1n2  target at 20 tirni hccaitse of the inverse fourth power variation of signal strength with range. 
 The memory of a clutter map is usually organized in a uniform grid of range and  azimuth cells, as illustrated in Figure 2.89. Each map cell will typically have 8 to  16 bits of memory so that it will handle the full dynamic range of signals at its input,  which makes it possible to detect a strong target flying over a point of clutter (some - times referred to as superclutter visibility ). The dimensions of each cell are a compro - mise between the required memory and several performance characteristics. 
 G. S. Nusinovich, B. 
 The standardized definition proposed by Sinsky and Wang78 is  used in this chapter. ch08.indd   40 12/20/07   12:52:53 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Instead it  might be sited at 20 m Iieiglit. with the slightly grcatcr loss being a price to pay for thc  convenience of the higher antenna location. Tlie above values apply to a particular cxpcrimetit $  in a particular location. 
 The results of this comparison  are presented in Figure 2.87, which shows the improvement factor for the optimum  and the adaptive MTI as a function of the power ratio Q (dB). When Q is small so that  chaff returns dominate, a significant performance improvement can be realized by  using all MTI filter zeros to cancel the chaff returns. The performance difference for  large values of Q is a result of an assumption made that the location of the third zero  remains fixed at the chaff doppler frequency. 
 NIFICANT SOURCE OF FALSE ALARM !MONG THE NONCOHERENT DEVICES  IT IS WORTH MENTIONING THE #&!2 DETECTOR n AND THE PULSE 
 G., k: The Ionospheric Sounder and Its Place in the History of Radio Science, Radio  Science, vol. 11, pp. 847-860, November, 1976. 
 Opticalprocessing hasprovedtobewellsuitedtotheneedsofSAR,exceptthatitisseldom doneinrealtime.Theradaroutputisusuallystoredphotographically andprocessed lateron theground. Inopticalprocessing, theelectrical signalsattheradaroutputareconverted tooptical imagesonfilm.Theweighting, filtering, andsummation ofsignalsareaccomplished withthe proper:opticallensesandtransparencies. Opticalprocessing isbasically twodimensional so thatprocessing intherangecoordinate ispossible withthesameapparatus. 
 BAND DATA AND LINK GEOMETRY MAY BE QUITE DIFFERENT  THE DATA COMPRESSION  DIVERSITY  AND ENCRYPTION MAY BE DIFFERENT 4HE MISSILE DATALINK WAVEFORM USUALLY MUST BE STEALTHY AND GREATLY ATTENUATED IN  THE DIRECTION OF THE TARGET SINCE ONE COUNTERMEASURES STRATEGY IS A DECEPTION REPEATER JAMMER AT THE TARGET (IGH ACCURACY TIME AND FREQUENCY SYNCHRONIZATION  INCLUDING RANGE OPENING AND DOPPLER EFFECTS BETWEEN BOTH ENDS OF THE LINK CAN DRAMATICALLY REDUCE THE EFFECTIVENESS OF JAMMING BY NARROWING THE SUSCEPTIBILITY WINDOW 4IME AND FREQUENCY SYNCHRONIZATION ALSO MINIMIZES ACQUISITION OR REACQUISITION TIME. 
 The benefits of using ECCM techniques such as  frequency agility, coherent doppler processing, very low sidelobe antennas, and SLC  can be easily assessed at a first approximation by properly modifying the parameters  involved in the radar equation. If, for instance, an SLC is adopted against an SOJ, its  net effect is to reduce jamming power by the amount of jammer cancellation ratio that  the SLC can offer. The prediction of radar range is difficult because of the many factors that are hard  to represent with models of the required accuracy. 
 Under  such circumstances, it is possible to determine the depth sufficiently accurately by  measuring the elapsed time between the leading edge of the received wavelet provided  the propagation velocity is accurately known. Although a greater depth resolution is achieved in wetter materials for a given  transmitted bandwidth because of the reduced wavelength in high dielectric materials,  earth materials with significant water content tend to have higher attenuation proper - ties. This characteristic reduces the effective bandwidth, tending to balance out the  change so that within certain bounds the resolution is approximately independent of  loss within the propagating material.FIGURE 21.5  Two resolved Ricker wavelets0.2 0.1 0 −0.1 −0.201282563845126407688961024 FIGURE 21.6  Two unresolved Ricker wavelets0.13 −0.13 01282563845126407688961024 ch21.indd   12 12/17/07   2:51:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 This was not very convenient when ﬂying from Chivenor (in Devon) and the Isles of Scilly were proposed as an alternative target. With the radar correctly tuned, Lundy Island could be detected at about 40 miles from 3000 ft, whilst the Isles of Scilly could be detected at up to about 30 miles. It was stated that adetection range of 25 –30 miles on the Isles of Scilly should indicate a detection range of about 15 miles on a submarine, whilst ranges of 15 –20 miles against the Scillies would indicate a range of less than 10 miles on a submarine. 
 $&#  %'     &# ' !" %%!# *  &%     
 Bush: Corn Growth as Monitored by Radal. IEEE Tratu., vol. AP-24, pp. 
 777–790, 1991. 103. C. 
 PASS FILTERING REJECTS THE SECOND SUM FREQUENCY  TERM OF %Q   PRODUCING THE )1 DEMODULATOR OUTPUT AS REPRESENTED BY %Q    6! T! JEE33JT JT )& 
 BAND RADAR DATA v IN  ST #ONF ON 2ADAR -ETEOROL   !-3  3EATTLE     PP n  - 3ACHIDANANDA AND $ 3 :RNIC  h#LUTTER FILTERING AND SPECTRAL MOMENT ESTIMATION FOR DOPPLER  WEATHER RADARS USING STAGGERED PULSE REPETITION TIME 024  v  * !TMOS /CEAN 4ECHNOL  VOL    PP n    $ "URGESS ET AL  h&INAL REPORT ON THE *OINT $OPPLER /PERATIONAL 0ROJECT *$/0  v n   ./!! 4ECH -EMO %2, .33, 
 PULSE  ETC  FILTERS BECAUSE THEY   REQUIRE A NUMBER OF PULSES TO REACH STEADY 
 In Proceedings of the IEEE Radar Conference, Boston, MA, USA, 17–20 April 2007; pp. 17–20. 5. 
 The magnetic ﬁeld at 300 km, 400 km, and 500 km was picked as the mid-value along each radio path, respectively. For each scene of PolSAR, FR estimation from Equation (2) may be biased by residual calibration errors, though PALSAR has been reported to be well calibrated [ 27,28]. Therefore, following [ 29], only pixels of SNR >10 dB were selected to estimate the ﬁnal TEC. 
 (8.25) can he  ex pressed as  (8.27)  The greater the gain of the antenna, the less the relative effect of the errors on the sidelobes.  Bv substituting the radiation intensity of Eq. (8.24) into the definition of gain (or directi­ vity) of Eq. 
 Nelson: The Relationship between Upper-Level Divergent Outflow Magnitude as Measured by Doppler Radar and Hailstorm Intensity, Preprints, 22d Conf. Radar MeteoroL, pp. 108-111, American Meteorological Society, Boston, 1984. 
 The velocity of the aircraft is about 105 m/s , and the acceleration is about 0.26 m/s2. The aircraft altitude is about 5 km. The squint angle is about 30◦. 
 H. Temme: A Solid State "Flux-I)rive" Fontrol Circuit for  Latching-Ferrite-Phaser Applications, Mic.rowtrre J., vol. 15, pp. 
 It ranges from 50 to 90 km, where electron density rapidly increases with altitude in the daytime. The maximum ionization in the D region occurs near the subsolar point and will be greatest during periods of highest solar activity (sunspot maximum). The D region may not be explicit in some ionospheric models where its effects are accounted for with an empirically derived path-loss calculation. 
 F.: The Story of Radar, Research (London), vol. 6, pp. 434-440, November, 1953. 
 Xing, X.M.; Zhu, J.; Wang, Y.; Yang, Y. Time series ground subsidence inversion in mining area based on CRInSAR and PSInSAR integration. J. 
 49. Thomason, J., G. Skaggs, and J. 
 12.1) isforced to oscillate inresonance with astandard cavity whose frequency differs from that ofthebeacon bytheintermediate frequency ofthe receiver. Theindicating equipment consists ofthe cathode-ray tube together with the auxiliary vacuum-tube circuits and other devices necessary to thesynthesis ofthedisplay. Those elements ofthe cathode-ray tube essential toageneral under- standing areshown inFig. 
 RANGE ACCURACY 4HESE EXAMPLES ALSO APPLY WHEN GROUND 
 The retraction of the antenna iscontrolled byedge interference, foranedge can cause blanking and diffraction ofaradar beam. The result isadistortion and deterioration ofthe antenna pattern. Any discontinuity such asthat caused byreinforcement oftheradome orbyapiece ofmetal may cause diffraction ifitintercepts theradar beam. 
 Parameter selections are made on the  basis of the best SNR in each nominal 50-nmi interval, but the selection is adjusted to  come from the adjacent lower frequency to avoid an optimistic bias. Then parameter  plots are generated as a function of range. The variables adopted here as parameters  are propagation losses, frequency, noise, and elevation radiation angle. 
   !.&03 
 Research radars have  rarely used STC owing to the attendant loss of sensitivity at short ranges. 19.3 DESIGN CONSIDERATIONS Four of the more significant factors that affect the design of meteorological radars are  attenuation, range ambiguities, velocity ambiguities, and ground or sea clutter. The  combination of these factors, along with the need to obtain adequate spatial resolu - tion, leads to a wavelength selection in the range of 3 to 10 cm for most precipitation  based applications. 
 The ability of the FM-CW radar to measure range provides an addi­ tional basis for obtaining isolation. Echoes from short-range targets-including the leakage  signal-may be attenuated relative to the desired target echo from longer ranges by propcrly  processing the difference-frequency signal obtained by heterodyning the transmitted and  received signals.  If the CW carrier is frequency-modulated by a sine wave, the difference frequency oblained  by heterodyning the returned signal with a portion of the transmitter signal may be expanded  in a trigonometric series whose terms are the harmonics of the modulating frequency/~ .9·18  Assume the form of the transmitted signal to he  sin ( 2~{0t + t{ sin 2n;fmt)  .m  where .fo = carrier frequency  fm = modulation frequency  11.f = frequency excursion (equal to twice the frequency derivation)  The difference frequency signal may be written  t'o = Jo(D) cos (2n;/;it -<Po)+ 2J1(D) sin (2~{4t -t/Jo) cos (2nfmt -<Pm)  -2J2(D) COS (21Tf4t -<Po) COS 2(2rrfmt- <Pm)  2J3(D) sin (2~fat -</>o) cos 3(2~fmt -<Pm)  + 2J4(D) cos (2rrf4l -</>o) cos 4(2~fmr -<Pm)+ 2Js(D) ··· (3.15)  (3.16) . 
 222. Sensors 2019 ,19, 743 Figure 8. (a) Relationship between soft soil thickness and subsidence rate. 
 The probability that the signal, when present, will be detected is called the probability of detection, Pd, and the probability that a noise fluctuation will be mistaken for a signal is called the false-alarm probability, Pfa. The notations /?max, Pr,min> and (S/N)min can then be replaced by more precise notation, using subscripts to denote the applicable values of Pd and Pfa. How- ever, the/a subscript is ordinarily suppressed, though implied. 
 170INTRODUCTION TORADAR SYSTEMS Receiver andservonoise.Another limitation ontracking accuracy isthereceivernoise power. Theaccuracy oftheanglemeasurement isinversely proportional tothe·squarerootofthe signal-to-noise powerratio.2Sincethesignal-to-noise ratioisproportional to1/R4(fromthe radarequation), theangular errorduetoreceiver noiseisproportional tothesquareof thetargetdistance. Servonoiseisthehunting actionofthetracking servomechanism whichresultsfrom backlash andcompliance inthegears,shafts,andstructures ofthemount.Themagnitude of servonoiseisessentially independent ofthetargetechoandwilltherefore beindependent of range. 
 LeMehaute and T. Khangaonkar, “Dynamic interaction of intense rain with water waves,”   J. Phys. 
 The initial image and the image with rotating have been shown in Figure 9. 301. Sensors 2019 ,19,6 3    (a) ( b)  Figure 9. 
 (13.8). First, the clutter echo power must be large  compared to the receiver noise power for Eq. (13.8) to be valid. 
 198–204, 1985. 53. R. 
 Some aircraft from 172 and 407 squadrons are shown in ﬁgure 3.12. It appears that the in-service detection performance of ASV Mk. III was highly variable. 
 3, no. 4, pp. 1-9, 1976. 
 PERSONNEL AND ANTI 
 The local oscillator must normally be positioned by the AFC to hold the signal in the IF bands. As shown, the system folds the doppler frequencies. To avoid this, either quadrature techniques must be employed or a second sidestep be introduced into the refer- ence channel. 
 1974. X2.Ewell.G.W.andA.M.Bush:Constrained Improvement MTIRadarProcessors. IEEETrailS.• vol.AI:S-11, pp.76Rno.September. 
 29. Mooney, D. H.: Post Detection STC in a Medium PRF Pulse Doppler Radar, U.S. 
 The effect, of course, is pre-  cisely the same, the electron gun setting up oscillations  within the rhumbatron cavity. There are several modi-  fications of the reflecting klystron. In one form the  reflecting electrode is negative, and repels the electrodes  . 
 Flannery, Numerical Recipes in C:  The Art of Scientific Computing,  2nd Ed. Cambridge, UK: Cambridge University Press, 1992,  pp. 213–222. 
 Bull. G éod.1984 ,58, 109–136. [ CrossRef ] 23. 
 Only afew ofthese equipments were built owing toprogress inthe development ofacentimetric scanning system, and totheinherent inabil- ityofthe CMHtofind height onmore than one target atatime. The SCR-615 was asimilar U.S. equipment, except that itwas designed asa fixed installation and employed an8-ft dish. 
 The best radar receiver is one with the narrowest RF instantaneous bandwidth com - mensurate with the radiated spectrum and hardware limitations and with good frequency  and impulse responses. A wide tuning range provides flexibility to escape interference,  but if the interference is intentional, as in the case of jamming, a change in RF fre - quency on a pulse-to-pulse basis may be required using switchable or electronically  tuned filters. If the RF filtering is located prior to RF amplification, the filter insertion  loss will have a dB for dB impact on the receiver noise figure, another sacrifice in noise  temperature to achieve more vital objectives. 
 LAYER RADOME HAS BEEN USED IN MANY  RADOME APPLICATIONS -ATERIALS FOR THIS TYPE HAVE INCLUDED FIBERGLASS 
 cc £ 02& 02&   3INUSOIDAL -ODULATIONS  2ADAR PERFORMANCE IS AFFECTED BY BOTH RANDOM AND SINU 
 Techniques 5 and 6 are used when the desired targets may have radar cross sections  similar to, or smaller than, a bird. Technique 1.  STC is the traditional method of suppressing birds and insects in a  radar with an unambiguous range PRF (a PRF low enough so that the range to targets  and clutter is unambiguous). 
 T. (ed.): "Jane's Weapon Systems, 1981-1982," pp. 449-596. 
 One set of  phase shifters produces a beam directed broadside to the array (0 = 0). Another set of three  phase shifters generates a beam in the 8 = + 00 direction. The angle 00 is determined by the  relationship 80 = sin -1(ti(j>)./2m/), where Liq, is the phase difference inserted between adjacent  elements. 
 Traditionally, ovals of Cassini are drawn as contours of a constant received signal  power or a received signal-to-noise ratio around a fixed baseline range, L. Although  these signal-dependent contours provide a sense of bistatic radar performance, they  do not show maximum/minimum detection ranges and coverage for variable base - lines, all parameters of operational interest. To remedy this problem, the concept of a  bistatic benchmark range,  or more simply benchmark,  is introduced. 
 Therefore, the 94-GHz-frequency region (3- mm wavelength) is generally what is thought of as a "typical" frequency representative of millimeter radar. The millimeter-wave region above 40 GHz has been further subdivided into . letter bands in the IEEE Standard, as shown in Table 1.1. 
 For m = 1 1,  e correspotlding frequency range is from i.l83/b to 1.264f0. The ability to radiate frorn tfie  nie array over more than one frequency region is of advantage when mutual interference  I~etweeti radars is of concern. It can also be of ilrlportance for niilitary applications in wliicli  frequency diversity is desired. 
 8.  Significant Wave Height Corrections  Adjustments to the SWH include the attitude/sea-state  correction already discussed along with a calibration cor­ rection implemented via a 256-entry look-up table. Cur­ rently, the table contains all zero entries. 
 FIGURE 25.27  Complex multiply with three real multipliersA BI QSUM+ − DC SUM SUM++ + − SUM− SUM+++ ch25.indd   23 12/20/07   1:40:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 
 D. Atlas, L. J. 
 In Proceedings of the European Conference on Computer Vision; Zurich, Switzerland, 6–12 September 2014; pp. 818–833. 36. 
 PORT ISOLATION  IS USED TO DETERMINE THE POWER LEVEL COUPLED DIRECTLY BETWEEN THE MIXER PORTS WITHOUT   FREQUENCY TRANSLATION 4HE SINGLE TONE INTERMODULATION LEVELS SPECIFY THE LEVELS OF   THE  NF ,   MF2 SPURIOUS SIGNALS  AS DISCUSSED PREVIOUSLY È°xÊ  "  Ê"-   /",- &UNCTIONS OF THE ,OCAL /SCILLATOR  4HE SUPERHETERODYNE RECEIVER UTILIZES ONE  OR MORE LOCAL OSCILLATORS AND MIXERS TO CONVERT THE SIGNAL TO AN INTERMEDIATE FRE 
 In any given setof precipitation conditions, the (S-band) or 10cm will suffer less attenuationthan the (X-band) or 3cm.Rain In the case of rain the particles which affect the scattering and attenuation take the form of water droplets. It is possible to relate the amount ofattenuation to the rate of precipitation. If the size of the droplet is anappreciable proportion of the 3cm wavelength, strong clutter echoes will beproduced and there will be serious loss of energy due to scattering andattenuation. 
 The antenna impedance  also changes with a change in feed position. Hence scanning a simple paraboloid antenna by  scanning the feed is possible, but is generally limited in angle because o( the deterioration in  the antenna pattern after scanning but a few beamwidths ofT axis.  Spherical reflectors. 
 FORMANCE OF %3! RADARS IS CITED AS A REASON FOR DECREASED UTILIZATION OF REFLECTOR ANTENNAS IN MANY OF TODAYS RADAR SYSTEM DESIGNS (OWEVER  THERE ARE STILL APPLICATIONS WHERE THE REFLECTOR ANTENNA IS WELL SUITED TO RADAR  APPLICATIONS AND WILL CONTINUE TO FIND APPLICATIONS IN THE FUTURE 4HREE RELEVANT EXAMPLES OF RADAR APPLICATIONS WELL SUITED TO THE USE OF REFLECTOR ANTENNAS ARE BRIEFLY DESCRIBED BELOW ,OW #OST 2ADAR  &OR VERY COST 
 PULSE CORRELATION PROPERTIES  AND TO OBSERVE THE EFFECT OF OFF 
 HAND AND  
 VAPOR RADIOMETER  AND EACH USED ONLY ONE FREQUENCY  SO THAT THEY HAD NO IN 
 31. Golomb, S. W., and R. 
 The difference channels are treated similarly with independent  amplitude weighting. This method may be extended to include combinations in  the other plane. Amplification on receiving or on both receiving and transmitting may be con - venient at the subarray level. 
 The AN/TPS-78 is an update to the AN/TPS-70/75 S-band, three- dimensional tactical radar family developed by the Northrop Grumman Corporation  (Figure 13.46). The AN/TPS-78 planar array shown in Figure 13.46 exhibits very low  FIGURE 13.45  AWACS antenna ( Courtesy of Northrop Grumman Corporation ) ch13.indd   65 12/17/07   2:41:13 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Even under manual control, the detailed shape of the  STC curve may have a complex adaptive element to it, in order to optimize thresholds  over a broader range. Under automatic settings, thresholding becomes increasingly sophisticated but  often still allows some manual optimization. The curve may adapt to internal calcula - tions made on returns from the last pulse or from a succession of pulses. 
 IGARSS ’86 , pp. 487–492, 1986. 106. 
 CLUTTER RATIO WHERE THE TARGET WAS AN URBAN AREA AND THE CLUTTER WAS REPRESENTED BY A PARK IN THE 3AN &RANCISCO IMAGE USED TO PRODUCE &IGURE  (E FOUND THIS WAS OBTAINED WITH TRANSMITTER POLARIZATION HAVING X E  BT    n  n  AND RECEIVER POLARIZATION OF  XE  BT         4HIS COMPARES WITH THE BEST RESULT USING LIKE 
 , "UESO 
 C., and C. A. Whitmer: "Crystal Rectifiers," MIT Radiation Laboratory Series, vol. 
 FIG. 25.10 X-band, vertically polarized, <rfl°, in-plane (<|> = 180°) data summary for rural land.108 Domville data108 within about 10 dB. The Cost data curves do not always ap- proach the bistatic specular ridge monotonically even though the terrain condi- tions appear to be more uniform. 
 • For all p, when the target's velocity vector is normal to the bistatic bisector (8 = ± 90°) the bistatic doppler is zero; the vector is tangent to a range-sum ellipse drawn through the target position (a contour of zero target doppler). • For all p < 180°, when the target's velocity vector is colinear with the bistatic bisector, the magnitude of the bistatic doppler is maximum; the vector is also tangent to an orthogonal hyperbola drawn through the target position, which is a contour of maximum target doppler. Isodoppler Contours. 
 Under external angle control the antenna either is posi- tioned by external slew commands or is referenced to inertial space or to the Shuttle axes. During automatic operation, angle, angle rate, range, and range rate measurements are made by the radar after track has been initiated. Under exter- nal angle control only range and range rate are measured. 
 LOBES IS PLOTTED VERSUS UNAMBIGUOUS RANGE THAT IS  AFTER THE RANGE AMBIGUITIES HAVE BEEN RESOLVED  !LSO SHOWN ARE THE NORMAL #&!2 THRESHOLD AND THE 34# THRESHOLD VERSUS RANGE ! DISCRETE RETURN IN THE SIDELOBES IS BELOW THE 34# THRESHOLD  AND A RETURN IN THE MAIN BEAM IS ABOVE THE THRESHOLD  SUCH THAT THE SIDELOBE DISCRETE CAN BE RECOGNIZED AND BLANKED WITHOUT BLANKING THE TARGET IN THE MAIN BEAM 4HE 34# ONSET RANGE REPRESENTS THE RANGE AT WHICH A LARGE DISCRETE TARGET IN THE SIDELOBES EXCEEDS THE #&!2 THRESHOLD. 
 However, this is by no means a safe assumption in the absence of specific knowledge. Array an- tennas in particular are likely to have significant ohmic losses in waveguides or coaxial lines used to distribute the power among the radiating elements. If separate transmitting and receiving antennas are used and if their maximum gains occur at different elevation angles (this is a possible though not a common situation), appropriate correction can be made by means of the pattern factors /,(8) and/r(6), contained in the pattern propagation factors Ft and Fr (Sec. 
 14. Tarchi, D.; Oliveri, F.; Sammartino, P .F. MIMO radar and ground-based SAR imaging systems: Equivalent approaches for remote sensing. 
           !    "#     !          
 It is shown in Fig. 7.6 for TV = 10. The pattern is repetitive, and the lo- . 
   #ANADA         # 6ARIOUS TO 1UAD#/3-/  )TALY         8 -ULTI 
 Simulated SAR images under the four look directions are given in Figure 12. The parameters of the simulations are shown in Table 5. Figure 11. 
 52. Kramer, E.: A Historical Survey of the Application of the Doppler Principle for Radio Navigation.  IEEE Trans .. 
 Other ferrite phase shifters. There have heen other kinds of ferrite phase shifters develop<.:d  over the years based on different principles or on variations of those descrih<.:d above.  Although the above phase shifters were discussed primarily as waveguide devices, some of  them may he implemented in coax, helical line, and striplinc. 
 Kerr, and C. Bachmann, “Automatic recognition of ISAR ship images,” IEEE  Transactions on Aerospace and Electronic Systems , vol. 32, no. 
 Martin, “Silent SentryTM Passive Surveillance,”  Aviation Week and Space Technology , June 7, 1999. 51. A. 
 È°{n  2!$!2 (!.$"//+  $IRECT $IGITAL 3YNTHESIZER  4HE $IRECT $IGITAL 3YNTHESIZER $$3  PRODUCES  WAVEFORMS USING DIGITAL TECHNIQUES AND PROVIDES SIGNIFICANT IMPROVEMENTS IN STABIL 
 Rept. TE-77-14, June, 1977.  90. 
 NOTCH -4) SECTION  AS ILLUSTRATED IN &IGURE  4HE NUMBER OF ZEROS USED IN THE FIXED 
 INDEPENDENT  CLEARLY NOT IN ACCORD WITH OBSERVATION 4HE FACET MODEL FOR RADAR RETURN IS EXTREMELY USEFUL FOR QUALITATIVE DISCUSSIONS   AND SO MODIFICATION TO MAKE IT FIT BETTER WITH OBSERVATION IS APPROPRIATE 4WO KINDS OF MODIFICATION MAY BE USED  SEPARATELY OR JOINTLY CONSIDERING THE ACTUAL RERADIATION PATTERN OF FINITE 
 Insulation between windings and adequate cooling must also betaken into account indesign. High-power transformers lend themselves most readily tooilinsulation because oftheinsulating and convection-cooling properties oftheoil. Inthelower-power range (200 kwand down) itis usually convenient touse solid dielectric materials, with aconsequent saving inweight and size. 
 OF 
 Radar System Engineering  Chapter 6 – Radar Receiver Noise and Target Detection  31        Figure 6.3  Noise temperature of outer space Tc in Kelvin (cosmic temperature,  extended noise sources) seen from the earth for linear polarization, as well  as the temperature of the atmospheric absorption noise Ta.  The brightness B c is associated with the noise temperature TB by the Rayleigh -Jeans Formula:   € Bc=2kTB λ2W m2HzSteradian (6.8)  The second special case demonstrates a semi -discrete noise source of the temperature in a na r- row area of the solid angle ΩB.  The background radiation is to be neglected. 
 When the platform is an aircraft, an on-board Inertial Navigation System (INS)   uses accelerometers and gyroscopes to measure the deviations. Sometimes a smaller  Inertial Measurement Unit  (IMU) relying on the same general principles is “strapped  down” very near the antenna. Without an absolute reference frame, the outputs of any  INS or IMU will drift with time as errors accumulate. 
 We should, if such a feat were humanly pos-  sible with components of normal radar values, then get -  a fairly straight-line graph of voltage against current.  It would, in fact, be a > and not ee ;  Naturally no human co-ordination of hand and eye could achieve such a result of controlling the series resistance to limit the voltage in this way, but we can get an approximation of the plan by charging the con-~ lenser through the effective anode resistance of a pen-  tode, or through a saturated diode. | _ Except at very low values, the anode current of a pentode is almost independent of its anode voltage—a characteristic of such valves brought about largely by the mechanical construction and geometric placing of _ the electrodes,.and one which is most useful for radar. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 3.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 decision whether to transform from elements to beams or subarrays. 
 The former requires a small overall horn size, while the latter requires large in- dividual horns (Fig. 6.20). Numerous methods have been devised to overcome this problem, as well as the associated high-difference sidelobes. 
 Van Dyk, D.A.; Meng, X.L. The art of data augmentation. J.Comput. 
 11.25. For viewing angles away from normal incidence, the plate edges are the dominant sources of echo, and the sin (x)/x pattern is the result of the indi- vidual edge contributions changing phase with respect to each other as the aspect angle changes. Noting from Table 11.1 that the radar echoes of straight edges per- pendicular to the line of sight are independent of frequency, the result of Eq. 
 Horn: A Low-Loss Microstrip X-band Diode Phase Shifter, 1974 Gollertrnlenr  Microcircuir App1ic.arion.s Conference Digest of Papers, pp. 58-59, June, 1974.  23. 
 Usually, targets of interest are anisotropic because they contain many dihedral and trihedral structures. Natural clutters and man-made clutters such as lawns, trees, and roads are usually isotropic. Therefore, pixels from these clutters have a lower aspect entropy while pixels from the targets have a higher aspect entropy. 
 262–267. 20. “Radar processing subsystem evaluation,” vol. 
 The mean-to-median ratioofthecrosssection.whichisameasure oftheamount offluctuation in thecrosssection. isfoundtobeindependent ofthemagnitude oftheradarcrosssectionbutis afunction ofthephysical sizeofthebirdrelativetotheradarwavelength.91Thusmeasure­ mentsofthemean-to-median ratiomightbeusedtodetermine thesizeofthebirdb"ing observed. Thefluctuations intheradarcrosssectionhavebeenattributed totherelative motions between thevarious partsofthebirdandtochanges inaspect,aswellastothe wing-beat frequency. 
 7.)REFERENCECELLS DETECTIONSINTEGRATOR . TABLE 8.1 CFAR Loss for Pfa = 10~6 and P0 = 0.9* * After Ref. 23. 
 Gilmour5 reports  that the mean time between failures (MTBF) of 11 different applications of klys - trons in radar systems varied from 75,000 hours to 5,000 hours, with an average of  37,000 hours for all 11 applications. (There are 8,760 hours in a year.) The VA-842  ch10.indd   6 12/17/07   2:19:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 13, pp. 313–320, 1978. 75. 
       
 SHAPE LOSS 4HE #ONFIRM DWELL IS TYPICALLY A (273 WAVEFORM AND ONLY EXAMINES  DOPPLER FILTERS WITHIN A WINDOW CENTERED ABOUT THE FILTER OF THE !LERT DETECTION CUE 4HE #ONFIRM DWELL MUST PRODUCE A  DETECTION CORRESPONDING TO THE !LE RT DETECTION IN ORDER  FOR A VALID DETECTION DECLARATION 4HE #ONFIRM DWELL IS USED TO MANAGE FALSE ALERTS AND PROVIDE A RANGE  MEASUREMENT FOR TARGET DETECTIONS 4HE !LER T AND #ONFIRM DETEC 
 This consists of one or more omnidirectional antennas and cancelation  circuitry used in conjunction with the signal from the main radar antenna. Jamming noise in  the omnidirectional antennas is made to cancel the jamming noise entering the side lobes of the  main antenna.52 An antenna can also be designed to have very low sidelobe levels to reduce  the efTcct of sidclobc jamming. Low sidelobe antennas require unobstructed siting if reflections  from nearby objects arc not to degrade the sidelobe levels. 
 TO 
 Mil. Microwaves Conf., pp. 103-108, London, Oct. 
  \60\  
  3HIPBOARD 3EARCH 2ADAR  4HE !.303 
 For certain FFT configurations, radix-4 and higher- radix butterflies provide some computational savings. Figure 25.42 shows a radix-2, 8-point FFT. The phase shifts are represented as  complex weights WNk, where N is the number of points in the FFT and k indicates the  particular phase shift applied. 
 Next, the team acquired an Avro Anson, K6260, which was well-suited to airborne rada r experiments and the team developed a fully airborne radar installation, RDF 2 , on 1.25 m, which could reliably detect ships at ranges of 3 –4 miles. The transmitter output of RDF 2 was about 800 W with two 316 A valves in push –pull, using the self-modulating or squegging principle to produce a pulse length of about 1 μs and a pulse repetition frequency (PRF) of about 1 kc/s. The receiver used RCA ‘Acorn ’valves in the RF and mixer stages and the display was a 9 ″Cossor CRT with an exponential time base. 
 FIGURE 12.31  Extended feed region improves sidelobes of offset feed (used on  ARSR-4): ( a) ray geometry and ( b) curved feed FIGURE 12. 32 ARSR-4 low-sidelobe reflector  with offset array feed ( Courtesy Northrop Grumman  Corporation ) ch12.indd   30 12/17/07   2:31:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Sensors 2018 ,18, 3750 performance based on global sparsity in this paper is obviously superior to that obtained by the traditional processing approach. Figure 7. Comparison for imaging performance of four approaches under different SNRs. 
 For alossless line halfawavelength long 2,=2,, (2) irrespective ofthe characteristic impedance ofthe line. This principle has many uses also, particularly induplexers (Sec. 11.5) and mixers (Sec. 
 Another problem is the vul- nerability of the map to pulsed interference from other radars. Clutter map AGC can serious degrade other critical signal-processing func- tions, and the following fundamental incompatibilities prevent its successful ap- plication to many types of radars: • Suppression of clutter by doppler filtering is degraded by change of attenuation from one interpulse period to the next. • Control of false alarms in distributed clutter (rain, sea) can be degraded by change of attenuation from one range sample to the next (see Sec. 
 Oneofthepurposes ofAGCinanyreceiver istopreventsaturation bylargesignals.The scanning modulation andtheerrorsignalwouldhelostifthereceiver weretosaturate. Inthe conical-scan tracking radaranA(iCthatmaintains thed-clevelconstant resultsinanerror signalthatisatrueindication oftheangular pointing error.Thed-clevelofthereceiver must hemaintained constant iftheangularerroristobelinearly relatedtotheangle~error signal voltage. ~. 
 CHAPTER 10 THE MAGNETRON AND THE PULSER BY G.B.COLLINS, J.V.LEBACQZ, AND M. G.WHITE THE MAGNETRON BY G.B.COLLINS Strenuous efforts were made bythe British, beginning about 1938, todevelop high-power pulsed sources ofradiation atvery high frequen- cies, because ofthe operational need formicrowave radar. Two lines of attack were followed. 
 It is difficult to make a precise comparison of  bistatic and rnonostatic radars because of the dissimilarity in their geometries. The coverage of  a monostatic radar is basically hemispherical. while the bistatic radar coverage is more or less  planar. 
 TO 
 The phase of the coho is then related to the phase of the transmitted pi~lse and  may be used as the reference signal for echoes received from that particular transmitted pulse.  Upon the next transmission another IF locking pulse is generated to relock the phase of the  CW coho until the next locking pulse comes along. The type of MTI radar illustrated in  Fig. 
 This CW radar uses frequency modulation of the waveform to allow  a range measurement. Surveillance radar . Although a dictionary might not define surveillance  this way, a  surveillance radar is one that detects the presence of a target (such as an aircraft or  a ship) and determines its location in range and angle. 
 RANDOM 
 Trunk, Naval Research Laboratory (CHAPTER 8) T. A. Weil, Equipment Division, Raytheon Company (CHAPTER 4) Lewis B. 
 They are  often so large that they might not be completely removed by MTI. Thus it is not uncommon  for MTI radar to have at its output many fixed point-scatterers that must be recognized so as  not to be confused with desired targets.  Probability density function for land clutter. 
 Skolnik, M. L: An Analysis of Bistatic Radar, IRE Trans., vol. ANE-8, pp. 
 NUMBERED COEFFICIENTS ARE USED TO  RESPECTIVELY  CREATE ) AND 1  AS SHOWN IN &IGURE  B AND C !FTER THE FILTERS  THE COMPLEX SIGNAL IS DECIMATED BY  TO PRODUCE A  -(Z OUTPUT  SAMPLE RATE 4HE FINAL SPECTRAL CONVOLUTION BY A n -(Z TONE IS ACCOMPLISHED BY NEGATING EVERY OTHER SAMPLE )N &IGURE   WE TRANSFORM THE SYSTEM OF &IGURE  TO MAKE IT MORE COMPUTA 
 Begovich. N. A.: Frequency Scanning, chap. 
 To this end, however, it is most important that microwave components employed in the feedthrough nulling as well as in the remainder of the microwave circuitry be as rigid as possible.8 It is customary to use a milled-block form of construction. In the rare cases where a single antenna plus duplexer or a pair of nested antennas has been used in an airborne high-power CW radar, the mechanical design problems have been all but insurmountable. Even in a ground-based radar, fans, drive motors, motor-generator sets, rotary joints, cavitation in the coolant, etc., are very troublesome. 
 NORMAL DENSITY  IT IS NECESSARY TO ESTIMATE MORE THAN ONE P ARAMETER AND THE ADAP 
 1See footnote onp.651. ... SEC. 
 Accordingly, a different form of the radar  equation must then be employed.) Propagation factors (Fp): Several propagation phenomena, including Faraday  polarization rotation, ground-reflection multipath, multiple hop propagation, and  ionospheric focusing may need to be included in the equation, depending on the  scenario of interest. Faraday rotation refers to the variation of the polarization of  the signal incident on the target as a function of time and distance, arising from its  propagation through the magnetized ionospheric plasma; linearly polarized trans - mitted signals often arrive in the target zone with a rotated axis of polarization but  still essentially linearly polarized. Since many targets have RCS that vary with  polarization, an important result is that the most favorable polarization will illu - minate the target recurrently. 
 GAIN AUXILIARY ANTENNA !N IMPLEMENTATION OF THE 3," PROCESSOR IS SHOWN IN &IGURE B  WHERE THE SQUARE 
 IEEE Tra11s., vol. AES-8, pp. 743-750, November, 1972. 
 The theoretical accuracy with which distance can be measured depends upon thc band­ width of the transmitted signal and the ratio of signal energy to noise energy. In addition,  measurement accuracy might be limited by such practical restrictions as the accuracy of the  frequency-measuring device, the residual path-length error caused by the circuits and trans­ mission lines, errors caused by multiple reflections and transmitter leakage, and the frequency  error due to the turn-around of the frequency modulation.  A common form of frequency-measuring device is the cycle counter, which measures the  number of cycles or half cycles of the beat during the modulation period. 
 108 INI'KODUCTION TO RADAR SYSTEMS  Blind speeds. The response of the single-delay-line canceler will be zero whenever the argu-  ment ?/; T in the amplitude factor of Eq. (4.6) is 0, rr, 2n, . 
 Power is coupled from the end of  the central stabilizing cavity by a circular waveguide. The geometry of the inverted coaxial  magnetron makes it suitable for operation at the higher frequencies. Figure 6.5 is an example. 
 Since vacuum tubes are not appropriate asswitches insuch low- impedance circuits, itisnot possible tofixthe sweep origin bymethods analogous tothat ofFig. 13.46. Ithas been necessary touseeither the method ofaseries dry-disk rectifier switched (ifnecessary) bythescan- ner, ortoapply some method ofwaveform balance. 
 Inpeacetime, usually only the surface- search function isofimportance. Because ofthe different beam-shape requirements, separate radar systems areordinarily used forairsearch and forsurface search, Airborne radar equipments employing aPPI areused forpilotage in thevicinity ofshorelines orover land. This pilotage may beofageneral navigational character, asitalways isinpeacetime and usually isinwar; oritmay beasprecise asthelimitations oftheradar will permit, forthe purpose ofblind bombing ofaradar target. 
 ATE A GEOPHYSICAL PARAMETER SUCH AS OCEANIC WIND SPEED TO THE OBSERVED CALIBRATED RADAR BACKSCATTER PROPERTIES OF THE ILLUMINATED SURFACE   AND SOUNDERS WHICH INCLUDES BOTH ATMOSPHERIC AND SUBSURFACE RADAR SYSTEMS  %ACH SECTION INCLUDES AN OVERVIEW OF ALL RELEVANT 3"2S  NOTING KEY TURNING POINTS OR WATERSHED INNOVATIONS IN THE THEMES HISTORY 3ELECTED EXAMPLES HAVE BEEN CHOSEN FOR MORE IN 
 Note that the clutter-to-noise ratio is a rms  power ratio measured at the A/D converter. A peak power ratio would be 3 dB higher.  FIGURE 4.15  Dynamic-range example ch04.indd   25 12/20/07   4:52:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
  
 M. I. Skolnik, Introduction to Radar Systems , New York: McGraw-Hill Book Company, 1962,  Chap. 
 The limiter also protects the receiver from signals from nearby radars that may not be strong enough to fire the T/R tubes but could be large enough to hurt the receiver. A ferritc duplexer (Fig. 4.2/?) uses a ferrite circulator,3 instead of T/R tubes, to send the transmitter power to the antenna and the received signals to the re- ceiver. 
 In the auto position, the rings were rotated at a speed of 300 –450 rpm, causing the energy to be transferred in a continuously varying proportion between one horn and the other. This resulted in a beam continuously scanning in azimuth over ±2.5 ° at a rate of between 300 and 450 scans per minute, or between 50 and 75 deg/s. This is shown in ﬁgure 4.9. 
 In this chapter, the receiver design is considered  mainly as a problem of extracting desired signals from noise. Chapter 13 considers the problem  of radar design when the desired signals must compete with clutter. The current chapter also  includes brief discussions of radar displays and duplexers. 
 Thepresence ofmorethanonepossible modeofoperation meansthatthemagnetron canoscillate inany oneofthese'frequencies andcandosoinanunpredictable manner. Thisistheessenceofthe stahility problem. Themagnetron mustbedesigned withbutonemodedominant. 
 CONTENT MINES 4YPICAL EXAMPLES OF RADAR IMAGES AT VARIOUS SCALES ARE SHOWN IN &IGURE  AND &IGURE  '02 HAS BEEN USED FOR SURVEYING MANY DIFFERENT TYPES OF GEOLOGICAL STRATA RANG 
 COUPLED  AND   LOADED 
 For the particular set of recorded measurements, it has been shown a substantially  enhanced performance of the adaptive filter over the nonadaptive filter . *  As mentioned previously, the lower frequencies might be preferred for long-range surveillance because the usual  radar equation does not include all the pertinent factors. In the jamming case, one should take account that the  jamming antenna on an aircraft has a lower gain at lower frequencies so the jamming power density might be less  at the lower frequencies. 
 Lematta, “A test of ocean surface cur - rent mapping with over-the-horizon radar,” IEEE Trans. Geosci. and Rem. 
 138. Skolnik, M. I., J. 
 Except fortheburning-in tendency, thenormal persistence issatisfactory through about the same scan intervals asisthat ofthe P-7screen. 13.3. The Selection ofthe Cathode-ray Tube.—Both electrostatic andmagnetic tubes areavailable invarious sizes and with various screens (Table 131). 
 ERROR 
 ,  &ILTERING OF THE %NTIRE 2ADAR 3YSTEM  &ILTERING PROVIDES THE PRINCIPAL MEANS  BY WHICH THE RADAR DISCRIMINATES BETWEEN TARGET RETURNS AND INTERFERENCE OF MANY TYPES 4HE FILTERING IS PERFORMED BY A VARIETY OF FILTERS THROUGHOUT THE RECEIVER AND .   2!$!2 2%#%)6%23   È°Óx IN THE SUBSEQUENT DIGITAL SIGNAL PROCESSING -OST RADARS TRANSMIT MULTIPLE PULSES AT  A TARGET BEFORE THE ANTENNA BEAM IS MOVED TO A DIFFERENT DIRECTION  AND THE MULTIPLE RETURNS ARE COMBINED IN SOME FASHION 4HE RETURNS MAY BE COMBINED USING COHERENT INTEGRATION OR VARIOUS DOPPLER PROCESSING TECHNIQUES INCLUDING -4)  TO SEPARATE DESIRED TARGETS FROM CLUTTER &ROM THE RADAR SYSTEM STANDPOINT  THESE ARE ALL FILTER 
 Shown also are the canceler config- urations assumed, with appropriate Z-plane pole-zero diagrams. The Z plane is the comb-filter equivalent of the S plane,16'17 with the left-hand side of the S plane transformed to the inside of the unit circle centered at Z = O. Zero fre- quency is at Z = 1 + y'O. 
 The objective of signal processing is to  detect and characterize echoes from scatterers of interest, either discrete (aircraft or  ships) or extended (the sea surface), and this is customarily achieved by decompos - ing the time series data from the receivers into the natural radar domain dimensions  of group range (based on time delay), direction of arrival (beam space), and doppler  frequency, hopefully separating the echoes of interest from unwanted clutter and noise.  The standard tool for this decomposition is the FFT, at least in operational skywave  radars, in part because it is computationally quite feasible to analyze the incoming sig - nal into typically ~102 range bins, 101 – 102 beams, and ~102 doppler cells, in perhaps  ~100 seconds, using general purpose computing hardware. Thus, the FFT (or DFT for  short transforms) is commonly used for the three dimensions of analysis. 
 In partic- ular, this makes conical-scan systems susceptible to AM jamming at the scan frequency (the spin frequency jammer).5 The monopulse system extracts the angular information instantaneously by comparing the difference and sum channel signals. The gain normalization can therefore be made instantaneous (fast or instantaneous AGC), and the external amplitude variations, since they affect sum and difference channels by the same relative amount, are never detected as erroneous guidance signals. The early systems all used conical scan for angle tracking because of its sim- plicity. 
 Among the 1792 modules per face, groups of 32 transceiver modules are op- erated as a subarray. In transmit, a high-power array predriver is used to drive 56 subarray driver amplifiers. Each of these power amplifiers provides enough RF drive for all 32 modules in one subarray. 
 SCALE MODEL  !N ADDITIONAL AD HOC SPECTRAL PARTITION IS  INTRODUCED BETWEEN THE LONGEST AND SHORTEST WAVE COMPONENTS OF THE SEA SPECTRUM  BUT  THIS PRODUCED ONLY MODEST IMPROVEMENT. 
 PULSE -4) CANCELER  AFTER 4 - (ALL AND 7 7 3HRADER Ú )%%%                    $"   &) &% ' # % $%% ! (! '"     &!' ) ) #%#+  &!' )#&  ) *  !   !   !  !  
 MATCHED SPATIAL CHANNELS ANTENNA AND RECEIVER  ARE DRIVEN BY JAMMING CANCELLA 
 BAND RADAR  SHOWN IN &IGURE   USES SIX SIMULTANEOUS FREQUENCY 
 Alperin, R. R. Bronski, J. 
 ,/ 
 ING BOTH DOPPLER AND SPATIAL TRANSFORMATIONS PRIOR TO 34!0 PROCESSING 4HE APPROPRIATE ARCHITECTURE SOLUTION DEPENDS UPON THE RADAR DESIGN CONSTRAINTS  4HE NUMBER OF ANTENNA ELEMENTS AND BEAMFORMING REQUIREMENTS ARE KEY DRIVERS IN THE     
 Modern mixers typically provide a  significant reduction in the effect of STALO amplitude modulation as their conversion  gain is relatively insensitive to LO power variation when operated at their specified  drive level. For systems requiring high sensitivity, AM noise can become disruptive if unin - tentional conversion of AM to PM noise occurs in the receiver chain. This process  can occur via suboptimum component bias techniques where high amplitude signals  or noise create a phase shift resulting in another phase noise contribution to the  receiver chain. 
 Considering the high SNR ratio, the threshold can generally be set as about 0.05 of the energy of the echo signal. At this time, most of the scattering centers on the target can be accurately reconstructed; whereas, with the increase of noise in echo signal, the set threshold value also increases, so as to avoid more false scattering points caused by noise in the generated image. If the sparsity Kis known, the reconstruction results obtained by applying the CS matching pursuit reconstruction algorithm are quite excellent but it is difﬁcult to obtain accurate sparsity in actual engineering. 
 vol. AP-8, pp. 629-631. 
 Therearethreebasicmethods foremploying semiconductor diodesindigitalphase shifters, depending onthecircuitusedtoobtainanindividual phasebit.Theseare:(I)the switched-line, (2)thehybrid-coupled, and(3)theloaded-line. Theswitched linewasshownin Fig.8.6.Eachphasebitconsists oftwolengthsoflinethatprovide thedifferential phaseshift, andtwosingle-pole, double-throw switches utilizing fourdiodes. Thehybrid-coupled phasebit,asshowninFig.8.7,usesa3-dBhybridjunction with balanced reflecting terminations connected tothecoupled arms.Twoswitches (diodes) control thephasechange.The3-dBhybridhastheproperty thatasignalinputatport1isdivided equallyinpowerbetween ports2and3.Noenergyappearsatport4.Thediodesacttoeither passorreflectthesignals.Whentheimpedance ofthediodesissuchastopassthesignals,. 
 12. Coquin, G. A., T. 
 7.1 if the phase distribution  across the aperture is not constant. Following the first side\obe are a series of minor lobes  which decrease in intensity with increasing angular distance from the main lobe. In the vicinity  of broadside (in this example 100 to 115°), spillover radiation from the feed causes the sidelobe  level to rise. 
 Models and Their Uses.  Knowledge of the conditions to be expected for a par - ticular radar deployment is vital to radar design, as well as providing a guide to echo  interpretation and a means to simulation and performance prediction. This type of  information, based on decades of ionospheric observations and theory, is conveniently  distilled in models that are widely available and used extensively. 
 Remote Sens. 2008 ,56, 1968–1975. 10. 
 The improvement factor (l) is equal to the subclutter visibility (SCV) times the clutter  visibility factor (Voe), In decibels, /(dB)= SCV(dB) + Voc(dB). When the MTI is limited by  noiselike system instabilities, the clutter visibility factor should be chosen as is the signal-to­ noise ratio of Chap. 2. 
 43/20, 18th May 1943 (TNA AIR 65/15) [6] Ward K D, Tough R J A and Watts S 2013 Sea Clutter: Scattering, the K Distribution and Radar Performance 2nd edn (London: Institution of Engineering and Technology) [7] Performance Stability of ASV Mark 6 Equipment on an Operational Squadron, TRE Report T.1894, July 1945 (TNA AVIA 26/896) [8] Pound R V 1948 Microwave Mixers MIT Radiation Laboratory Series vol 16 (New York: McGraw-Hill) [9] Horst M, Dyer F and Tuley M 1978 Radar sea clutter model Int IEEE AP/S URSI Symposium (IEEE Antennas and Propagation)Airborne Maritime Surveillance Radar, Volume 1 7-13. IOP Concise Physics Airborne Maritime Surveillance Radar, Volume 1 British ASV radars in WWII 1939–1945 Simon Watts Chapter 8 Conclusions 8.1 Other ASV radars 8.1.1 USA radars [ 1] The ASV radars described in chapters 1–5were designed in the UK and installed on British aircraft. Coastal Command also ﬂew on long-range American aircraft made available under the Lend –Lease programme. 
 P . Wei et al.10,  the Boeing Company. Original data courtesy of the Boeing Company, Seattle, Washington .)40 30 20 10 0RCS (dBsm)−10 −20 −30 −40 −50−100−80−60−40−20 0 Azimuth (deg)20 40 60 80 100VV, VH, HH-5, HV-5,8-feet Square Plate 0.79 GHz ch14.indd   9 12/17/07   2:46:49 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 JAMMING TECHNIQUES AT THE 'ERMAN !!! RADARS IN 7ORLD 7AR )) v  SUPPL TO )%%% )NT 2ADAR #ONF 2EC  PP n  -AY n     $ # 3CHLEHER   )NTRODUCTION TO %LECTRONIC 7ARFARE   .ORWOOD  -! !RTECH (OUSE  )NC     $ # 3CHLEHER   %LECTRONIC 7ARFARE IN THE )NFORMATION !GE   .ORWOOD  -! !RTECH (OUSE  )NC     " * 3LOCUMB AND 0 $ 7EST  h%#- MODELING FOR MULTITARGET TRACKING AND DATA ASSOCIATION v  IN -ULTITARGET 
 The detail with which path tracing is treated can vary greatly. A geometrical optics code that envolves integration along the ray as de- scribed by Jones and Stephenson51 can provide paths in three dimensions, includ- ing delays and losses for both ordinary and extraordinary rays. When the details of electron distributions are uncertain, such comprehensive calculations are ex- cessive. 
 (I) 0.  C -30 I ltlls, low rough 0 .: u Arizona mountainous (I)  V)  VI Defowore Boy V) e -40 - Arizona deserl u  N J marshland  -50  -60 UHF 1000 L C X 10,000  Frequency (MHz)  (al  Downtown phoenix x  0-Highest median value x----------------..._  SS WOO x --..__x ·- @  .:9 -10 - Phoeai,, SS > 25,000 I~~:~ 0  b  0 NJ residential  (I) o -20 X X X  ~ NJ rnrnl ,---::::::::1 i~ g 30 _Arizona hills, low rough )(~------=::::~~x  fj Arizona mountainous x~x---- ~ Ar,zonodeserfX~  ~ -40 -Arizona cullivoled x x----x  u formfond ------- (" N.J marshland x ------ -50 ·· Delaware Boy x  I -GQL-~~~~~~-U-H~F~~~~-1-0~0~0~L~~~~~~~~C::--~~~~X~10,000  Frequency_ (MHz)  (bl  Fi~ure B.11 Medi:in values of <T0 as a function of frequency. Grazing angle= 8°. 
 However, other aspects of performance may suffer and should be examined carefully in the tradeoff process. Another ad- vantage of phase-only monopulse, relative to vector and amplitude-only, is that the need for precise amplitude matching channel to channel is reduced. Phase-only monopulse processing does not utilize the full target angle- of-arrival information available in the two beams. 
 STANT 
 Although the above are limitations to the phased array in radar, they are probably not  sufficiently serious to restrict its greater use. However, the major limiratioa that has limited the  widespread use of the conventional phased array in radar is its high cost, which is due in large  part to its co~nplexity. The software for the computer system that is needed to utilize tllc  inherent flexibility of the array radar also contributes significantly to the system cost and  con~plexity. 
 58. Hopkin, V. D.: Colour Displays in Air Traffic Control, International Conference on Displays for  Man-Machine Systems, Apr. 
 In conclusion, the proposed studies represent valid examples of the fertile research ongoing in the ﬁeld of SAR processing and applications, and demonstrate as SAR imaging still presents large margins for investigations. Funding: This work was partially supported by the Italian Ministry of University and Research (MIUR) in the framework of “CLOSE to the Earth” project (ARS01_00141), PON Ricerca e innovazione 2014–2020. Acknowledgments: The guest editor would like to thank the authors’ contribution to this Special Issue and all reviewers for providing valuable and constructive recommendations. 
 The undesired fluctuations that cause difficulty occur at about the same rate as the scan rate. Since target scintillation energy of aircraft is concentrated in the lower frequency range below approximately 100 Hz (particularly the trouble- some propeller modulation), it is desirable to increase the scan rate as high as possible. The maximum practical rate is one-fourth of the pulse repetition fre- quency (PRF) so that four pulses provide a complete scan with one each up, down, right, and left. 
 The transmitter  power does not appear explicitly. Increasing the transmitter power will indeed increase the  target signal, but it will also cause a corresponding increase in clutter. Thus there is no net gain  in the delectability of desired targets. 
  .   -4) 2!$!2  Ó°Èx Ó°£ÓÊ , ,Ê-9-/ 
 In contrast, bipo- lar devices are minority carrier devices, and since minority carriers are thermally generated, bipolar power transistors tend to generate localized hot spots and can become thermally unstable. Resistive ballasting techniques used in both the col- lector and the emitter leads of a bipolar transistor reduce the intrinsic device gain and efficiency but offset the thermal-instability problem. In the power FET, how- ever, large active cell areas can be combined without using these ballasting tech- niques and without experiencing the problems of thermal runaway. 
 5 of "Radar Handbook," M. I. Skolnik (ed.),  McGraw-Hill Book Co., Inc., New York, 1970. 
 EFFECTIVENESS CONSIDERATIONS !NGLE OF ARRIVAL IS THE MOST IMPORTANT SORTING PARAMETER AVAILABLE TO THE DEINTERLEAV 
 J. Pattern Recognit. Artif. 
  
 31 Antenna scanrate.Theseaclutterbackground doesnotchangesignificantly duringthetime theusualcivil-marine radarantenna (witha20rpmrotation rate)scansbyaparticular clutterpatch.Thatis,theseacanbeconsidered" frozen"duringtheobservation time.Fora medium-resolution X-bandradaratlowgrazingangles,thetimerequired fortheseaclutter echotodecorrelate isabouttoms.16•21Anypulsesreceived fromseaclutterduringthistime willbecorrelated andnoimprovement insignal-to-clutter ratiowillbeobtained byintegra­ tion.(Thisisunlikereceiver noisesinceintegration ofsignalpulsesandnoisecanprovide significant improvement insignal-to~noise ratio,asdescribed inSec.2.6.)Although theclutter received duringasinglescanpastatargetwillbecorrelated, theseasurfacewillusually chang~ bythetimeofthenextantenna scansothattheclutterwillbedecorrelated fromscantoscan. Thusscan-to-scan integration canusuallyresultinanimprovement oftarget-to-c1utter ratio. Tomakeavailable moreindependent clutterechoes, theantenna rotation ratecanbe increased.21•23If,forexample, theradarantenna hasa 20beamwidth, apulserepetition frequency of3600Hz,anda20rpmrotation rate,therewillbe60pulsesreturned froma targetoneachscanoftheantenna. 
 Kingsmill and R. M. Wakimoto,   “Kinematic, Dynamic, and Thermodynamic Analysis  of a Weakly Sheared Severe Thunderstorm over  Northern Alabama ,” Monthly Weather Review,   vol. 
 26. McGraw-Hill Book Company, New York, 1948.  15. 
 CLUTTERv CONTROLS 4HE GAIN CON 
 A. F. Barnett: On Some Direct Evidence for Downward Atmospheric  Reflcctiori of I:lcctric Rays, I'r.oc.. 
 This may involve detecting a coded beacon on the tanker,  skin tracking tankers and other aircraft at close range. Station keeping ranges can be  between 30 and 1000s of meters. Special short-range radar modes are usually used for  this purpose. 
 m2  R = range to target, m  I-, = orie-way pr opiigatiori loss  L, = systelil losses  'I'lte correspondirlg equation for tile bistatic radar is  \\lli*rc (;, - 11;\11~11iittirig ;111terlr1;1 g;~iri ill dirt'ction of target  (;, = rcccivir~g arltcrlrla gi1i11 ill dircctior~ ol' target  rr, = I4sl;\tic cross sectioti. m 2  I), = irarlsrnitter-to-hr gct distallcc, 111  I), = receiver-to-target distance, 111  L,(r) = propagation loss over trarisn~itter-to-target path  L,(r) = propagation loss over receiver-to-target path  Equations (14.35) and (14.36) represetit but one of the several forms in which the radar  equation may be written. They are not meant to be complete descriptions of the performance  or radar systems since they do not cxplicitly include many important factors, but they are  suitable if or~ly relative comparisons are to be made. 
 AGC is necessary to keep the gain of the angle-tracking loops constant for stable automatic angle tracking. Some monopulse systems, such as the two-TRANSMlTTER TR DEVICE RECEIVER FRONT ELEVATIONDIFFERENCE SUM AZIMUTHDIFFERENCE FEEDHORNSSUM CHANNELTR MIXERATR TRANSMITTER AGCRANGETRACKER IFAMPLIFIERAMPLITUDEDETECTORVIDEOAMPLIFIER ELEVATIONDIFFERENCECHANNELMIXERIFAMPLIFERPHASE-SENSITIVEDETECTORELEVATION-ANGLEERROR HYBRIDJUNCTIONDIFFERENCECHANNELAZIMUTHMIXERIFAMPLIFIERPHASE-SENSITIVEDETECTORAZIMUTH-ANGLEERROR LO . channel monopulse, can provide instantaneous AGC or normalizing as described later in this section. 
 THE 
 IEEE. vol. 65. 
     . 
  AND DIFFERENCE 
 A 64-element network, for example, requires 192 directional couplers and 160 fixed-  phase shifters. The construction of a large Butler network requires a large number of  cross-over connections in the transmission lines. These can present practical difficulties in the  fabrication of the microwave printed circuits used to make up the device.z6 Many beams also  require many parallel receivers, an added complexity. 
 § ©¨¨¶ ¸·· PDI       .   05,3% $/00,%2 2!$!2   {°{Ç WHERE N. .E ª «­­ ¬­ ­         PDI PDIFOR3WERLING)TARG GETCHI 
 Beamwidths of ≤ 1° are commonly used for longer-range radars. Admittedly, this  is somewhat arbitrary, but the choice of 1 ° is based upon several decades of experi - ence. A 1 ° beam will provide a cross-range resolution of 1 km at a range of 60 km. 
 12] HOWRADAR WORKS 3 the radar picture would have been unaffected while photography or ordinary vision would have been useless. 1.2. How Radar Works.—The coined word rodaris derived from the descriptive phrase “radio detection and ranging. 
 Excellent  results may be obtained for NS, as small as 2 bits (per I and per Q) by adapting the  quantization thresholds to the mean signal level. (Refer to Section 18.4 for more on  this topic.) Quantization noise, which is larger for fewer bits, is proportional to signal  strength; hence it is a factor in the MNR budget. Exacting applications such as interfer - ometry are better served by more bits per sample, subject to the rate and volume limits  of the data handling subsystems. 
 SWITCHING TECHNIQUE SUCH AS THE EQUAL 
 SPREADING CONSIDERATIONS  SINCE DUR ING THE &- PERIODS  THE  CLUTTER IS SMEARED IN FREQUENCY AND CAN APPEAR IN FREQUENCY REGIONS NORMALLY CLEAR OF CLUTTER  ! NO 
 The four-thirds earth approximation has several limitations. It is only an average value  and should not be used for other than general computational purposes. The correct value ofk  depends upon meteorological conditions. 
 OUTPUT  CURVE )LLUSTRATED IS THE EFFECT OF NONLINEARITY . £È°ÓÓ  2!$!2 (!.$"//+  .OTE THAT ONLY THE RATIO OF TRANSMITTED TO RECEIVED POWER IS REQUIRED  SO THE TECH 
 This may be identical to the acquisi - tion zone but is there to provide an alarm if any tracked target passes into the zone. In common with other radar trackers, strategies have to be evolved to cope with  the target being potentially invisible in some scans. IMO requires that the specified  performance is maintained when the target is invisible in up to 50% of scans. 
 It is dependent on feed type, say, horn or dipole. This H field is nor- malized such that the total power into a surrounding sphere (the magnitude of the tangent field squared) is equal to 1 W. This may be done by numerical in- tegration using as much symmetry as possible to reduce computation time. 
 The dual-mode spiral has been the preferred choice, since a single aperture generates all the direction-finding information (and thus makes full use of the limited available space), requires only two receiver channels, has excellent polarization character- istics, and is frequency-independent.20 The four arms of the spiral are fed by a mode-forming network to form a sum G) and a delta (A) mode (hence the name dual-mode). The directional informa- tion is contained in the relative amplitude and phase of the S and A channels. The A/2 ratio represents the magnitude of the BSE (the angle off axis in a cone of rotation about the boresight), while the relative phase indicates the direction on the cone of rotation. 
 LIMITED DETECTION  AS APPLIES ESPECIALLY TO AIRCRAFT TARGETS  THE ADDITIONAL COM 
 Pearson, “Moving target experiment and analysis,” Hughes Aircraft Report No. P76-432,   pp. 5–15, 22–35, December 1976, declassified 2/28/94. 
 GRAPHIC RADAR ALTIMETER MISSIONS 4/0%80OSEIDON  *ASON 
  ARE PARALLEL TO LEADING EDGES 8 
 These distributions might not always fit the observed data, but  they are fair approximations in many cases and are used nevertheless for convenience. The  chi-square distribution is described by two parameters: the average cross section a..,, and the  number of degrees of freedom 2m. Analysis39 of measurements on actual aircraft Hying  straight, level courses shows that the cross-section fluctuations at a particular aspect are well  fitted by the chi-square distribution with the parameter m ranging from 0.9 to approximately 2  and with aav varying approximately 15 dB from minimum to maximum. 
 Adaptive array prin- ciples have found a thorough mathematical treatment since the early 1970s.40 The basic result is given by the expression of the optimum set of weights: W = JJiIVr1S* (9.6) where M = E(V514V7) is the Af-dimensional covariance matrix of the overall dis- turbance (noise and jammer) V received by the array and S is the Af-dimensional vector containing the expected signal samples in the array from a target along a certain direction of arrival. The similarity of Eq. (9.6) to Eq. 
 Proper initial phasing ofthe data-transmitter shaft can bemade by methods analogous tothose ofdisplay-sector selection (Chap. 13); alternatively, acontrolled phase shifter can beinserted between the a-f filter and theamplifier. Aconvenient index foruseinthis alignment can beprovided bytransmitting one ormore angle markers along with the video signals, asillustrated inFig. 
 The PSPs perform signal processing on arrays of sensor  data. The GPPs perform processing in which there are large numbers of conditional  branches. The MCU issues programs to PSPs, GPPs, and BM, as well as manages  overall execution and control. 
           
 Typically, the receiver input noise will exceed that of the noise due to the receiver  itself, so that the receiver has only a small impact on the system noise temperature or  noise figure. Thus, when defining dynamic-range parameters, such as signal-to-noise  ratio, it is important to specify whether the noise level being referenced is the receiver  noise or total system noise. Minimum Signal of Interest. 
 POLARIZED RADAR FOR  CLOUD STUDIES v )%%% 4RANS 'EOSCI 2EMOTE 3ENS  VOL   PP n    ' &ARQUHARSON  % ,OEW  7 # ,EE  AND * 6IVEKANANDAN  h! NEW HIGH 
 2.2711) and  the fan beam (Fig. 2.27b). The pencil beam is axially symmetric, or nearly so. 
 ACKNOWLEDGMENTS The authors would like to acknowledge the efforts of and extend their sincere grati - tude to several individuals who helped them immensely in the preparation of this  chapter. First, to Mr. Gregory Tavik of NRL for his thorough review of this chapter  and the many excellent comments he made. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.40  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 On these occasions, the flux of meteors can be so high that they can cause serious  obscuration of target echoes. 
 The far~out sidelobes of a cylindri­ cal array are generally large and broad in angle, as compared to those of a planar array. The  design of efficient feed networks, the phase and amplitude control devices, distributed trans­ mitter and/or receiver modules, and the control algorithms and logic are other problem areas.  Similar problems occur with other conformal-array shapes. 
 It Jifkrs  from the klystron amplifier by the continuous interaction of the electron beam and the RF  field over the entire length of the propagating structure of the traveling-wave tuhc rathcr than  the interaction occurring at the gaps of a relatively few resonant cavities. The chief character­ istic of the TWT of interest to the radar system engineer is its relatively wide bandwidth. A  wide bandwidth is necessary in applications where goqd range-resolution is required or where  it is desired to avoid deliberate jamming or mutual interference with nearby radars. 
 pp. 101–110, 1998.  93. 
 C.: Effective Antenna Temperature Due to Oxygen and Water Vapor in the Atmosphere, J.  Appl. Phys., vol. 
 1971.  OTHER RADAR TOPIC'S567 14.Brown. W.M..andR.J.Fredricks: Range-Doppler Imagining withMotion Through Resolution Cells.IEEETrellis..vol.A[S-5.pp.9X102.January. 
 Feed support. The resonant half-wave dipole and the waveguide horn can be attanged to feed  the paraboloid as shown in Fig. 7.9a and b. 
 Katz ) ch16.indd   36 12/19/07   4:56:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 Summaries of clutter measurements made before about 1970  may be found in several of the standard reference books on radar2,3 and radar clutter.4   Among the programs of this period, the most ambitious was that pursued in the  late 1960s at the Naval Research Laboratory (NRL),25 in which an airborne four-   frequency radar (4FR), operating with both horizontal and vertical polarizations at  UHF (428 MHz), L band (1228 MHz), C band (4455 MHz), and X band (8910 MHz),  made clutter measurements upwind, downwind, and crosswind in winds from 5 to  50 kt for grazing angles between 5° and 90°. The system was calibrated against stan - dard metal spheres dropped from aircraft, and wind speeds and waveheights were  recorded in the measurement areas from ship instruments. Typically, samples of s  0 for a given set of radar and environmental parameters are  scattered over a wide range of values and in the NRL measurements were organized  into probability distributions of the type shown in Figure 15.2. 
 /- )N THE PREVIOUS EDITION OF THIS BOOK  THIS SECTION COVERED SUCH HARDWARE PROBLEMS  AS TIME AND PHASE SYNCHRONIZATION BETWEEN TRANSMITTER AND RECEIVER CONSTRAINED BY  TECHNOLOGY AVAILABLE IN THE S 0HASE STABILITY WAS ALSO AN ISSUE 3INCE THEN MASSIVE ADVANCES IN DIGITAL SIGNAL CORRELATION AND PROCESSING  COUPLED WITH GREAT REDUCTIONS IN THE COST OF  HARDWARE TO EXECUTE SUCH PROCESSING  HAVE MITIGATED THESE  PROBLEMS -ANY RECENT BISTATIC RADAR PROGRAMS HAVE DEMONSTRATED QUITE ADEQUATE SYNCHRONIZATION AND STABILITYAS WELL AS DETECTION PERFORMANCEUSING OFF 
 808–811, 1974. 90. H. 
 This provides a  three-dimensional "image" of the target since the azimuth and elevation of each scatterer is  given along with the range. Figure 5.20 is an example of the type of radar image that might be  obtained with an aircraft. This technique not only improved significantly the tracking accur-  acy as compared with a longer pulse conventional tracker, but its unique measurement  properties provide additional capabilities. 
 CFAs might have  an efficiency from 40 to 60%, use a lower voltage than linear-beam tubes, are lighter  in weight and smaller in size, and have been found from UHF to K band. However,  they have relatively low gain and their stability and noise are not as good as found in  linear-beam tubes, so their application for MTI radar has been limited. Because of the  CFA’s low gain, the crossed-field amplifier transmitter needs more than one stage of  RF amplification, each with its own power supply, modulator, and controls. 
 However, theaxisoftheellipseistiltedatanangletoboththetimeandfrequency axes.This. 418 INTRODUCTION TO RADAR SYSTEMS  Figure 11.12 Ambiguity diagram for a single frequency-  modulated pulse. (Also called the chirp pulp-compression  waveform.)  particular waveform is not entirely satisfactory. 
 Funding: This research was funded by the National Natur1al Science Foundation of China (NSFC) under Grants 41604157, 41601483, and 61871352, and by the National Key Laboratory of Electromagnetic Environment. Acknowledgments: Special thanks goes to Bodo Reinisch for his help in offering the account of DIDB. We also thank the Japanese Aerospace and Exploration Agency and the Alaska Satellite Facility for making the PALSAR data publicly available. 
 Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 5.6 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 on a single chip or on separate chips depending on yield, complexity, speed, cache  size, and so on. Each processor array may consist of programmable signal processors  (PSP), general purpose processors (GPP), bulk memory (BM), input-output (I/O), and  a master control unit (MCU). 
 ING FROM A DIRECTION  P IS PROPORTIONAL TO ITS PROJECTED AREA 4HE GAIN WITH SCANNING   THEREFORE  IS   '! COSPP   PLH    )F THE APERTURE IS MADE UP OF  . EQUAL RADIATING ELEMENTS AND IS MATCHED TO ACCEPT  THE INCIDENT POWER  THEN THE CONTRIBUTION TO THE OVERALL GAIN IS THE SAME FROM ALL  ELEMENTS  HENCE   'P     .'EP  G    WHERE 'E IS THE GAIN PER ELEMENT )T FOLLOWS FROM %Q  THAT THE MATCHED ELEMENT  POWER PATTERN IS   '! .E  C O SPP PL    AND THE NORMALIZED RADIATION AMPLITUDE PATTERN OF THE MATCHED  ELEMENT OR MATCHED   ELEMENT PATTERN IS   %E  C O SPP     &OR A GIVEN ELEMENT SPACING  S  THE TOTAL NUMBER OF RADIATORS  . IN THE AREA  ! IS .    !S  AND %Q  GIVES   'S E  C O SPP § ©¨¶ ¸· PL  7HEN THE ELEMENT SPACING IS  S   K  THEN THE POWER PATTERN OF AN ELEMENT THAT IS  PERFECTLY MATCHED AT ALL SCAN ANGLES IS   'EP     O COS P   !ND THE PEAK ANTENNA GAIN IN THE DIRECTION OF SCAN  P  IS   'P    O .G COS P    WHERE THE EFFICIENCY TERM  G  ACCOUNTS FOR LOSSES AND FOR A NONUNIFORM APERTURE DISTRI 
 C. Schleher, Introduction to Electronic Warfare , Dedham, MA: Artech House, 1986, pp. 280– 283, 109–128. 
 A given radar might work equally well with a mechanically positioned  array, a lens, or a reflector antenna if they each had the same radiation pattern, but such a  radar could not be converted efficiently to an electronically scanned array by simple replace-  ment of the antenna alone because of the interdependence of the array and the other  portions of the radar.  Radiation pattern.' " Consider a linear array made up of N elements eqhaIIy spaced a  distance rl apart (Fig. 8.1). 
 2.3isjust 2,iftheantenna temperature and thetemperature ofR areboth 291°K. For the open circuit termination, N=1.Actually, over-all noise figures of10orlower arenot now uncommon inthe best microwave receivers. Anoise figure of10and abandwidth of3Me/see, forexample, imply that asignal of1.2X10–’3 watts will besufficient to increase the receiver output byanamount equal tothe average noise output 2.9. 
 1976.  30. ('roriey. 
 AMPLIFIER THAT EMPLOYS SEVERAL RESONANT CAVITIES IS CALLED A  GYROKLYSTRON  AND WHEN A TRAVELING 
 IN PERSISTENCE OF ORIGINAL RADAR MONOCHROME #24S HAVE TO BE PROVIDED ELECTRONICALLY  4HE TRAIL LENGTH IS REQUIRED TO BE USER SELECTABLE IN  UNITS OF TIME 7HEN 4RUE -OTION IS SELECTED  TRAILS CAN BE CHOSEN BY THE OPERATOR TO BE SHOWN IN EITHER TRUE OR SHIP 
 1 IIF I:I I:<.I RONI('AI 1.Y STFFRFV PHASEL) ARRAY ANTENNA IN RADAR 327  Table 8.2 Exarnple of priorities for a tactical systeni12 '  0 Dedicated niode  Burnthrough Previo~isly scheduled events  Target definition > that capture radar for  Special test ) long periods of time  1 Engnpenietlts  Engaged hostile  Own missile  I'rccng;~gcd host i lc  2 Tinlc-critical  High-priority transition  High-priority confirmation  Clorizon search  1 Spcci;~l rcclticct  Ilurt~ll~rot~gl~  Target definition  Spcci;11 <c:111<  'l';~rget acquisitiori  4 lligh-priority tracks  Confirrned hostile  Assumed hostile  Unevaluated  Controlled friendly  Confirmation  Track transition  5 Low-priority track  Assumed friendly  Confirmed friendly  6 Above-horizon search  All coverages  Special test  7 Simulation. diagnostics. and dummies  Table courtesy RCA. 
 TRACK DIRECTION  (OWEVER  THE ORBITS ALTI 
 103. J. P. 
 FREQUENCY MANAGEMENT /F COURSE  THE RADAR ITSELF IS AN OBLIQUE SOUNDER  BUT ITS SOUNDING DATA IS RESTRICTED TO THE FREQUENCY  WAVEFORM  AND SCAN PROGRAM OF ITS PRIMARY SURVEILLANCE TASK !N ADJUNCT OBLIQUE SOUNDER CAN PROVIDE INFORMATION IN  &)'52%   4HE NUMBERS IN THIS FIGURE SHOW THE 3.2 IN D" AS A FUNCTION OF FREQUENCY AND RANGE IN  THE FORM OF A TYPICAL OBLIQUE BACKSCATTER SOUNDING *ANUARY   '-4 DAY   33.   LOCATION  n. AND   n7  BEARING n 3EE THE TEXT FOR A DESCRIPTION OF RADAR PARAMETERS .   (& /6%2 
 429–436, 1967. 76. W. 
 A " typical" IF amplifier for an air-surveillance radar might have a center frequency of 30  or 60 MHz and a bandwidth of the order of one megahertz. The IF amplifier should be  designed as a n~atclted filter; i.e., its frequency-response function H(f) should maximize the  peak-sigtial-to-mean-noise-power ratio at the output. This occurs when the magnitude of the  frequency-response function 1 H(f)( is equal to the magnitude of the echo signal spectrum  I S(.f') 1, and the phase spectrum of the matched filter is the negative of the phase spectrum of  the echo signal (Sec. 
 §S PULSE WIDTH AT A  DUTY CYCLE $RIVE POWER FOR THE TWO &)'52%   0!6% 0!735(& 42 MODULE CONSISTS OF TRANSMIT MODULE AND RECEIVE  MODULE IN A NESTED CONFIGURATION OF CAST ALUMINUM HOUSINGS  0HOTOGRAPH COURTESY OF  2AYTHEON #OMPANY  .   3/,)$ 
 (/2):/. 2!$!2   Óä°ÎÇ )N SUMMARY  THE SEA ECHO POWER IN A RESOLUTION CELL   IS GENERALLY THE LARGEST ECHO  SIGNAL   GENERALLY EXISTS IN THE OPEN OCEAN EVEN IN RELATIVE CALM   VARIES AS THE  SQUARE OF RESONANT WAVEHEIGHT  WHICH IS FREQUENTLY SATURATED AT THE HIGHER FREQUEN 
 TION THRESHOLDS ARE DESIGNED TO ACHIEVE OVERALL FALSE ALARM TIME EQUAL TO CONVENTIONAL SEARCH ONE EVERY FEW MINUTES  !LONG WITH USING THE SAME 02& IN !LERT AND #ONFIRM  THE TIME BETWEEN THESE DWELLS  OR  LATENCY  SHOULD BE MINIMIZED TO PREVENT A VALID !LERT  DETECTION FROM BEING ECLIPSED DURING THE #ONFIRMATION DWELL ,OW 
 OPERATING RADAR CAN FORCE THE DELAY OF THE SHIP IN PORT  AT GREAT COST TO THE OPERATOR ÓÓ°xÊ /, 
 26.) . FIG. 4.9 Cloverleaf slow-wave circuit. 
 THE 
 Daniels, “Time domain design of a TEM horn antenna for  GPR,” presented at Millennium Conference on Antennas and Propagation, April 2000. 24. D. 
 (13.15) must be reduced by a factor  of 2 In 2 to describe the equivalent volume that accounts for tlie echo power received by tlre  two-way antenna pattern from distributed ~lutter.'~ Thus the radar equation of Eq. (13.14)  call be written  In the above. the relationship G = n2/tIRc$R for a gaussian beam~hape~~ was substituted. 
 ThedashedcurvesofFig.4.35showtheimprovement inMTJprocessing thatistheo­ retically possible withDPCAandathree-pulse delay-line canceler. (NotethattheDPCA corrects onlyonecanceler ofamultiple-stage MTI.63)Thecurveforx=0appliesforno platform motionandrepresents themaximum improvement offeredbyanideaplatform­ motioncancellation method.Itisseenthatwhentheclutterspectral widthissmall,asfor overland clutter,asignificant improvement isofferedbyDPCA. Thelimitation totheimprovement factorduetoantenna rotation, orscanning modula­ tion,canbereducedbyamethod similartoDPCA.S1,58,66DPCAappliesthedifference patterninquadrature (90°phaseshift)tothesumpatternwhilecompensation forscanning modulation requires thedifference patterntobeappliedinphasewiththesumpattern.Thusit. 
 For exam- ple, consider a clutter-to-signal ratio of 60 dB. A mere 0.1 percent second har- monic distortion would yield a clutter harmonic of the same magnitude as the target. If a missile velocity of 2000 ft/s is assumed (40 kHz doppler at X band), the harmonic would occur at 80 kHz, and the usable doppler spectrum, which the speedgate would be able to search, could extend no further than 80 kHz (in practice a safety margin of a few kilohertz would have to be maintained at both ends of the search region, further limiting achievable performance). 
 For each of the determined kr, the variation of ky with kxis shown by the arc in Figure 5. (IIHFWLYH6SHFWUXP Figure 5. Spectrum of traditional interpolation. 
 Geophys. Res., vol. 71, pp. 
 U. Palma, and D. Palumbo: The Behavior of Phase-sensitive Detectors,  Nuouo cimento, vol. 
 The sum and difference signals are multiplied in a phase-sensitive detector to obtain  both the magnitude and the direction of the error signal. All the information necessary to  determine the angular error is obtained on the basis of a single pulse; hence the name trtono-  pulse is quite appropriate.  Amplitude-comparison monopuke. 
 )Asymptote IJ+10 +20 Antenna elevation angle.deg0'--__-'-__---' -'-_----" -10oc ~50- c <r thesea,(3)theantenna alwayspointingatthegalacticcenter(4)nointenseradiostarsinthe antenna pattern, (5)resistive lossesinthereflector, feed,andtransmission lineabsorbing 2 percentoftheincident power,and(6)thefeedproducing aparabolic illumination taper. 12.9MICROWAVE-RADIATION HAZARDS Highpowermicrowave energycanproduce spectacular effects.Ithasbeenreported for example, that50kWofUHFpowerradiating fromtheopenendofa6-byis-in.waveguide willcauseordinary lightbulbstoexplode, fluorescent lampsmanyfeetawaytolightup,anda pieceofsteelwooltoexplode intoarcs.62Itisnotsurprising, therefore, thatmicrowave energy, ifofsufficient intensity, isahealthhazardandcanproduce biological damage inhumans. Heating isthechiefeffectofmicrowave radiation onlivingtissue.Incontrolled dosages, radiation heatingisbeneficial andformsthebasisofdiathermy, atherapeutic heatingofthe tissuebeneath theskin.Frequencies ranging fromHFtomicrowaves havebeenusedfor diathermy.631he heatingeffectsofmicrowave radiation havealsobeenappliedcommercially intheformofmicrowave ovens,usedforcooking foodrapidly. 
 Stoddard: An Analysis of Conical Scan Antennas for Tracking, IRE Natl.  Cotrtl. Record, vol. 
 OFF FOR MANY BROADCAST TRANSMITTERS  WHICH IS SUFFICIENT TO PREVENT INTERFERENCE IN ONE 
 WEIGHT -4) CANCELER Ó°nÊ  /Ê  1// 
 Intheinteraction space(5)theelectrons interact withthed-celectric fieldandthe magnetic fieldinsuchamannerthattheelectrons giveuptheirenergytotheRFfield.The magnetic field,whichisperpendicular totheplaneofthefigure,passesthrough theinteraction spaceparalleltothecathode andperpendicular tothed-celectricfield.Thecrossed electric andmagnetic fieldscausetheelectrons tobecompletely bunched almostassoonastheyare emitted fromthecathode. Afterbecoming bunched, theelectrons movealonginatravcling­ wavefield.Thistraveling-wave fieldmovesatalmostthesamespeedastheelectrons, causing RFpowertobedelivered tothewave.TheRFpowerisextracted byplacingacoupling. 'I' @ Figure 6.1 Cross-sectional sketch of the classical  cavity magnetron illustrating component parts. 
 (The latter  will be referred to simply as morfopu)se;f  When the target is being tracked, the'signal-to-noi~e ratio available from the monopulse  radar is greater than that of ~;eorticiil;scan· radar, all other things being equal, since the  monopulse radar views the target'ifihi'peak of its sum pattern while the conical-scan radar  views the target at an angle off the .. peak of the antenna beam. The difference in signal-to-noise  ratio might be from 2 to 4 dB. 
 PRESSION  INTERMODULATION  OR CROSS MODULATION DISTORTION !UTOMATIC .OISE 
 Buswell, “ASR-12: A next  generation solid-state air traffic control radar,” IEEE 1998 Radar Conference , pp. 9–14. 57. 
 A. LeMone, and J. W. 
 thesuccessive A-scope sweepsisshowninFig.4.3fThemovingtargetsproduce, withtime,a "butterfly" effectontheA-scope. Although thebutterfly effectissuitable forrecognizing movingtargetsonanA-scope, itis notappropriate fordisplayonthePPI.Onemethodcommonly employed toextractdoppler information inaformsuitable fordisplayonthePPIscopeiswithadelay-line cancder (Fig.4.4).Thedelay-line canceler actsasafiltertoeliminate thedoccomponent offixedtargets andtopassthea-ccomponents ofmoving targets.Thevideoportionofthereceiver isdivided intotwochannels. Oneisanormalvideochannel. 
 (4.26) for tlic doublc cat~cclcr is shown in Fig. 4.30. The parameter describing the  curves is f,A. 
 The late gate opens at the center and closes at the end of  the main range gate. The early and late gates each allow the target video to charge  capacitors during the time when the gates are open. The capacitors act as integrators. 
 !NTENNA &EED 4ECHNIQUES  -ONOPULSE 
 OND LOCAL OSCILLATOR OR )1 DEMODULATOR REFERENCE FREQUENCIES CAN BE USED TO PROCESS THE DIFFERENT FREQUENCIES 7ITH THE USE OF HIGH 
 MTT-13,  pp. 785-788, November, 1965.  33. 
 (/2):/. 2!$!2   Óä°Î -ETEORS ARE USUALLY CLASSIFIED AS  SPORADIC  OCCURRING MORE OR LESS RANDOMLY AS THE  %ARTH MOVES AROUND THE SUN  AND  SHOWERS  SUCH AS THE ,EONIDS AND THE %TA !QUARIDS   WHICH OCCUR ON PREDICTABLE DATES WHERE THEIR ORBITS INTERSECT THE %ARTHS ORBIT           
 DOMAIN ILLUSTRATION SHOWN PREVIOUSLY IN &IGURE  LEADS TO THE CONCLU 
 SPACE-BASED REMOTE SENSING RADARS  18.496x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 The vertical dimension of the antenna (together with range, incidence, and wave - length) determined the width of the illuminated swath on the surface. This provided an  upper bound on the imaged swath width, which, in the case of Magellan , was less than  the swath actually illuminated. The imaged swath width was chosen to be somewhat  wider than the orbit-to-orbit translation of Venus’ surface due to planet rotation. 
 DIMENSIONAL ELECTRONIC BEAM STEERING 4HESE ARE REFLECTORS  OF WHICH #HINAS (* 
 The mixer current was displayed on the ammeter dial and was set at about 0.5 mA, using the mixer current control. Additional control of the LO amplitudeAirborne Maritime Surveillance Radar, Volume 1 3-8. and hence the mixer current could be achieved by directly adjusting the coupling to the klystron by physically rotating the link from the front panel coaxial socket. 
 Their work was also  abandoned after a short while.   Then in the years 1925/26 Breit and Tuve conducted investigations on the earth’s Ionosphere.  From this time on the importance of Radar for Navigation, especially at sea, became increasingly recognized. 
 Appl. Phys., vol. 24,  pp. 
 The backscatter from the earth's surface is generally many orders of magnitirde larger  than the echo from desired moving targets. Thus HF radar must employ some form of doppler  processing such as MTI, pulse-doppler, FM-CW, or CW radar to separate desired moving  targets from clutter. The equivalent of a high-pass filter must be used to detect moving aircraft  and missiles and reject stationary surface clutter. 
 4- the resolution is said to be about 500 m.46) If limitations on peak power require a co'nsidcrably  longer pulse width in order to acliieve the necessary energy within the pulse. some form of  pulse compression could be used. (The ARSR-3 does not have pulse compression, however.)  FM (chirp) is a common choice of pulse-compression waveform. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 21.38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 depth because of the attenuation characteristics of the ground. 
 PARAMETER THRESHOLD IS RARELY USED &)'52%   #URVES OF PROBABILITY OF DETECTION VERSUS SIGNAL 
 Sensors 2019 ,19, 3344 Tint=Tis the integration time equal to the microburst time width; Nis the number of main pulses for aperture synthesis in one imaging segment; nis the number of imaging segments. In case the spectral ﬂux density of the direct pulsar signal is 10−23⎭bracketleftBigW m2·Hz⎭bracketrightBig , assume the spectral ﬂux density of the asteroid’s signal S=10−26⎭bracketleftBigW m2·Hz⎭bracketrightBig . To evaluate SNR assume N=128,ΔF=2×109Hz; Dpr=300 m;λ=0.03 m; D=100 m; Tint=2×10−6s;R0/prime=109m. 
 HORIZON RADAR v  )%%% 4RANS 'EOSCI AND 2EM 3ENS   VOL    PP n     ( , 4OLMAN  7!6%7!4#( )))  .ATIONAL 7EATHER 3ERVICE  HTTPPOLARNCEPNOAAGOVWAVES WAVEWATCHWAVEWATCHHTML   * , !HEARN  3 2 #URLEY  * - (EADRICK  AND $ " 4RIZNA  h4ESTS OF REMOTE SKYWAVE MEASURE 
 and M. A. F. 
 P.M..andJ.D.Lawson: TheTheoretical Precision withWhichanArbitrary Radiation Pattern MayAeOhtained withaSourceofFiniteSize,J.lEE.vol.95,pt.IlIA,pp.362-370. Septemher. 194X. 
  TRANSISTOR  
 2ADAR  3ONAR .AVIG  VOL   NO   PP n  $ECEMBER   , 2 6ARSCHNEY AND $ 4HOMAS  h3IDELOBE REDUCTION FOR MATCHED RANGE PROCESSING v   )%%%  2ADAR #ONFERENCE  PP n  . ,EVANON AND % -OZESON   2ADAR 3IGNALS  .EW 9ORK )%%% 0RESS  *OHN 7ILEY  3ONS  )NC     PP     2 ( "ARKER  h'ROUP SYNCHRONIZATION OF BINARY DIGITAL SYSTEMS v  IN #OMMUNICATION 4HEORY    7 *ACKSON ED   .EW 9ORK !CADEMIC 0RESS    PP n  0 * %DMONSON  # + #AMPBELL  AND 3 & 9UEN  h3TUDY OF 3!7 PULSE COMPRESSION USING ¾  "ARKER CODES WITH QUADRIPHASE )$4 GEOMETRIES v  )%%% 5LTRASONICS 3YMPOSIUM  PP n  4 &ELHAUER  h$ESIGN AND ANALYSIS OF NEW 0N K  POLYPHASE PULSE COMPRESSION CODES v  )%%%  4RANSACTIONS ON !EROSPACE AND %LECTRONICS 3YSTEMS  VOL   NO   PP n  *ULY   2 4URYN AND * 3TOVER  h/N BINARY SEQUENCES v  0ROC !M -ATH 3OC   VOL   PP n    *UNE   $ ' ,UENBURGER  h/N "ARKER CODES OF EVEN LENGTH v  0ROC )%%%  VOL   PP n  *ANUARY    2 4URYN  h/N "ARKER CODES OF EVEN LENGTH v  0ROC )%%% CORRESPONDENCE   VOL   P    3EPTEMBER   , "OMER AND - !NTWEILER  h0OLYPHASE "ARKER SEQUENCES v  %LECTRONICS ,ETTERS   VOL   NO    PP n  .OVEMBER     ( -EIKLE  -ODERN 2ADAR 3YSTEMS  .ORWOOD  -! !RTECH (OUSE    P   " , ,EWIS  h2ANGE 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section.  RADAR CROSS SECTION  14.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 Examples of RCS patterns for aircraft are shown in Figures 14.11 and 14.12. 
 The original H 2S Mk. II scanners used coaxial cable and a dipole feed but this was changed on ASV Mk. III to a waveguide and horn feed, to give better elevation coverage at 2000 ft [ 2]. 
 The distinct advantage of this technique is  that any number of bits may be implemented while using only a single toroid. They  have the advantage of low loss and relatively high power operation. Devices that han - dle up to 100 kW of peak power have been built. 
 The imaginary part hQ(n) of the impulse response, in contrast, has nonzero coef - ficients only at even numbers of delays, so it is realized with double delays only. The architecture can then be further simplified by moving the decimation ahead of  the 2t   delays, as shown in Figure 25.17 b. This changes each double delay to a single  delay at the lower clock rate at which the filter computations are now more efficiently  clocked. 
 LOOP TEST 
 The input and reference signals are of the same  frequency. The output d-c voltage reverses polarity as the phase of the input signal changes  through 180". The magnitude of the d-c output from the angle-error detector is proportional to  the error, and the sign (polarity) is an indication of the direction of the error. 
 FERENT FREQUENCY  WIDTH  AND BORESIGHT ORIENTATION  ARE REQUIRED TO SUPPORT MULTIPLEXED ALTIMETRY AND SCATTEROMETRY AS WELL AS IMAGING AND RADIOMETRY 4HE RADARS MASS IS ^  KG  AND ITS INPUT POWER REQUIREMENT IS  ^ 7 0EAK DATA RATES ARE ON THE ORDER  OF  KBITS !LL MODES OPERATE AT + U BAND  '(Z  )N ITS MOST FAVORABLE LOWER  ALTITUDE IMAGING GEOMETRY  GROUND RANGE AND AZIMUTH RESOLUTIONS ARE ON THE ORDER OF  KM  AT  LOOKS !T HIGHER ALTITUDES  MORE LOOKS ARE GATHERED TO PARTIALLY OFFSET THE DEGRADED RESOLUTION 4HE RADARS NOISE 
 The field strength is a maximum when the argument of the sine term in Eq. (12.5) is equal  to n/2. 3x12, . 
 L.A.DuBridge. The Army and Navy development laboratories were glad todepend onthe new Radiation Laboratory foraninvestigation ofthe usefulness forradar ofthenew microwave region oftheradio spectrum. They were fully occupied with the urgent engineering, training, and installation problems involved ingetting radar equipment that had already been developed out into actual military and naval service. 
 Practically, somewhat more trouble isinvolved, since zero frequency filters are stable because neither the frequency nor the filter tuning can change, while both possibilities are present forfrequencies other than zero. Usually also, either byaccident ordesign, various harmonics ofj,will bepresent and these also must befiltered out. This isthe first case n-ehave encountered ofageneral and almost exactl theorem tothe effect that any periodic modulation can produce 10,000 Sooo 60Q0 4000 2000 z :1000 “-k800 ~600 40Q 200 10010 20 4060100 200 400 1000 rm,xinmiles 510.- -Maximum repetition or modulation fmquenry as afunction ofmaximum unambiguous range. 
 TURE WITH THE SUM AND HAS THE AMPLITUDE RELATIONSHIP  $    T A N S I NQQP LQ  £¤ ¦¥³ µ´7    WHERE 7 IS THE DISTANCE BETWEEN THE PHASE CENTERS OF THE TWO HALVES OF THE ANTENNA  (ENCE  A CHOICE OF 7   6X4P AND K    WOULD IDEALLY RESULT IN PERFECT CANCELLATION )N PRACTICE  A SUM PATTERN IS CHOSEN BASED ON THE DESIRED BEAMWIDTH  GAIN  AND  SIDELOBES FOR THE DETECTION SYSTEM REQUIREMENTS 4HEN THE DIFFERENCE PATTERN  $P   IS  SYNTHESIZED INDEPENDENTLY  BASED ON THE RELATIONSHIP REQUIRED AT DESIGN RADAR PLATFORM  &)'52%   0HASOR DIAGRAM SHOWING THE RETURN FROM A POINT SCATTERER DUE TO PLATFORM  MOTION. Î°£Ó  2!$!2 (!.$"//+  SPEED AND ALLOWABLE SIDELOBES 4HE TWO PATTERNS MAY BE REALIZED BY COMBINING THE  ELEMENTS IN SEPARATE CORPORATE 
 Trunk, G. V.: Detection Results for Scanning Radars Employing Feedback Integration, IEEE Trans.,  vol. AES-6, pp. 
 194- 196, April, 1958.  18. Elliott, R. 
 CUTTER TYPE CONSTANT  AMPLITUDE FALLING SHARPLY TO ZERO AT THE HALF 
 The  selection of the proper threshold level is a compromise that depends upon how important it is  if a mistake is made either by ( 1) failing to recognize a signal that is present (probability of a  miss) or by (2) falsely indicating the presence of a signal when none exists (probability of a false  alarm).  When the target-decision process is made by an operator viewing a cathode-ray-tube  display, it would seem that the criterion used by the operator for detection ought to be  analogous to the setting of a threshold, either consciously or subconsciously. The chief differ­ ence between the electronic and the operator thresholds is that the former may be determined  with some logic and can be expected to remain constant with time, while the latter's threshold  might be difficult to predict and may not remain fixed. 
 ERATOR 0HOTO COURTESY OF ./!!.73  .   -%4%/2/,/')#!, 2!$!2   £°£Ç &IGURE  SHOWS AN EXAMPLE OF RADAR REFLECTIVITY DATA FROM THE &REDERIC  /KLAHOMA   RADAR AS A LINE OF INTENSE THUNDERSTORMS AND ASSOCIATED RAINFALL PASS THROUGH THE COVER 
 WAVELENGTH DIAMETER CENTER 
 The grid resolution of the wind ﬁeld is 25 km ×25 km over the 317. Sensors 2019 ,19, 1529 ocean surface. The wind speeds and directions from left to right are listed as follows: (a) 5.44 m/s, 159.5◦and (b) 3.80 m/s, 273.6◦, where the wind direction is deﬁned as the angle clockwise from the north in degrees. 
  !A   B   
 C., and J. Frank: Array Antennas, chap. 11 of" Radar Handbook," M. 
 EIGENVECTOR DECOMPOSITION OF THE INTERFERENCE COVARIANCE MATRIX  - SEE AGAIN #HAPTER  OF &ARINA  AND 4ESTA AND 6ANNICOLA !N  IMPORTANT TECHNIQUE THAT MITIGATES THE DELETERIOUS EFFECTS OF THE NOISE EIGENVECTORS  THUS CONTINUING TO MAINTAIN A PRESCRIBED LEVEL OF LOW SIDELOBES IN THE ADAPTED ARRAY PATTERN IS THE SO 
 SIST OF FOUR OR FIVE #0)S  WITH THE RANGE AND VELOCITY DETERMINATIONS BEING BASED ON THE BEST GROUPING OF THREE RETURNS 4HE ACTUAL IMPLEMENTATION MUST BE BASED ON THE PARAMETERS OF THE SYSTEM AND PERMISSIBLE TIME ALLOCATED FOR EACH DWELL 4HE 02&S OF THE #0)S SHOULD BE SELECTED TO MINIMIZE THE CHANCE OF FALSE RADIAL  VELOCITY DETERMINATIONS /NE METHOD OF SELECTING 02&S IS SIMILAR TO SELECTING PULSE INTERVAL RATIOS FOR STAGGERED 02& OPERATION  AS DESCRIBED IN 3ECTION  &OR EXAM 
 Oneofthebeamsistiltedslightlyupward, whiletheotheristiltedslightly downward, toachieve thesquintneededforamplitude­ comparison monopulse inelevation. Therefore thehorizontal projection oftheantenna pat­ ternsisthatofaphase-comparison system, whilethevertical projection isthatofan amplitude-comparison system. Boththeamplitude-comparison-monopulse andthephase-comparison-monopulse trackers employtwoantenna beams(foronecoordinate tracking). 
 1975.  122. Kay. 
 R. Nicolas, D. R. 
 #7 RANGE 
 G.H.:HelixFrequency Scanning Feed,Microwave J.,vol.8,pp.39-44,December, 1965. 71.Dewey,R.:Corrugated Waveguide Frequency Scanning Aerials,Proceedings International Confer­ enceonRadar-Present andFuture,Oct.23-25.1973,lEEConference Publication no.105. pp.100-105.. 
  .   -4) 2!$!2  Ó°x HAVE IN THE PAST BEEN REFERRED TO AS BIPOLAR VIDEOS  BUT A MORE CORRECT TERMINOLOGY IS  THAT OF THE COMPLEX ENVELOPE OF THE RECEIVED SIGNALS !N EXAMPLE OF SUCH A BIPOLAR VIDEO EITHER ) OR 1   RECEIVED FROM A SINGLE TRANSMITTED PULSE AND INCLUDING BOTH CLUT 
 Haeger and J. J. Lee, “Comparisons between a shaped and nonshaped small cassegrain  antenna,” IEEE Trans. 
  Ê *  
 9.15] SCI HEIGHT FINDER 299 determination. The height-finder beam, atthe 10-cm band, is3.5° in azimuth by1.2° inelevation, and scans linearly one way for 10.5° in elevation from thehorizon up,tentimes asecond. Itmakes continuous height-finding possible onsmall aircraft out to50miles, and farther on larger planes. 
 TARGET DETECTIONS 4HE SYSTEM MUST PROVIDE A THRESHOLD THAT THE TARGETS WILL CROSS AND THE CLUTTER RESIDUE WILL NOT CROSS Ó°ÈÊ  *,"6 
 !TLANTIC COAST OF THE 5NITED 3TATES AND SHOULD BE A GOOD APPROXIMATION FOR ANY LOCATION WHERE TRANSMISSION PATHS ARE THROUGH THE MIDDLE MAGNETIC LATITUDES  &)'52%   ! SPECIFIC EXAMPLE OF 3.2 AND CLUTTER 
 !IR 7IND 0ROFILING 2ADARS  !NOTHER FORM OF DOPPLER RADAR THAT HAS  BECOME WIDELY USED  ESPECIALLY IN THE RESEARCH COMMUNITY  IS THE SO 
 This leads to a fully adaptive MTI implementation using a more complex adaptation  algorithm, as discussed below. Such an adaptive MTI may provide a performance  close to the optimum discussed in Section 2.7. In order to illustrate the difference in performance between such candidate MTI  implementations, a specific example is considered next. 
 It is not until  we start to use very high frequencies, resulting in wave-  lengths of 10 centimetres and less, that the new technique  is startling to one grounded in conventional broadcast  methods.  For most radar outfits it is more convenient to talk  in terms of frequency than of wavelength. You will find  it easy to translate one term into another if you recall  that 14 Mcs (megacycles) represents 20 metres, 28 Mcs  ro metres, 56 Mcs 5 metres, 112 Mcs 24 metres, and  _ 224 Mcs 1} metres. 
 D" RANGE RESOLU 
 Keeler, “Innovative signal utilization and processing,” Chapter 8 in Radar  in Atmospheric Science: A Collection of Essays in Honor of David Atlas , R. Wakimoto and R.  Srivastava (eds.), Meteorological Monographs, V ol. 
 Ryde and Ryde21 calculated the effects of rain on mi- crowave propagation and showed that absorption and scattering effects of rain- drops become more pronounced at the higher microwave frequencies, where the wavelength and the raindrop diameters are more nearly comparable. In the 10-cm band and at shorter wavelengths the effects are appreciable, but at wavelengths in excess of 10 cm the effects are greatly decreased. It is also known that sus- pended water droplets and rain have an absorption rate in excess of that of the combined oxygen and water-vapor absorption.22 In practice, it has been convenient to express rain attenuation as a function of the precipitation rate R, which depends on both the liquid-water content and the fall velocity of the drops, the latter in turn depending on the size of the drops. 
 DRIVEN AND PARASITIC ANY OR ALL OF WHICH COULD CONTRIBUTE TO THE SCATTERED CLUTTER SIGNAL &OR EXAMPLE  THE COMMON 3TOKES WAVE   HAS A QUASI 
 This :Itwasnamed after theEnglish equivalent oftheAmerican slotmachine used for gambling.. SEC. 7.51 RADAR IN THE RAF FIGHTER COMMAND 227 information was displayed inlights toa“teller,” who passed theinfor- mation over atelephone line toFighter Command Headquarters. 
 M.: ilistory of the Directional Antenna in the Standard Broadcast Band for the  Purpose of Protecting Service Area of Distant Stations, IRE Trarrs., vol. PGBTS-7, pp. I- 55. 
 Moore, “Acoustic Simulation of radar returns,” Microwaves , vol. 1, no. 7, pp. 
 Gunn, K. L. S., and T. 
 Lee, H.; Lee, J.-H.; Kim, K.-E.; Sung, N.-H.; Cho, S.-J. Development of a Truck-Mounted Arc-Scanning Synthetic Aperture Radar. IEEE T rans. 
 Radar antennas are characterized by directive beams which are scanned, usually rapidly.  The parabolic reflector, well known in optics, has been extensively employed in radar. The vast  majority of radar antennas use the parabolic reflector in one form or another. 
 BASED DUCTING 4HE NONDETECTION SKIP 
 IMPULSE 
 lfrcord, vol. .1. pt. 
 Frequency multiplication and direct digital synthesis are described in Section 6.13.  Conventional phase locked loop synthesizers are occasionally used, but their fre - quency switching times and phase settling responses are generally inadequate to meet  the stringent radar receiver-exciter requirements. Phase locked loops are more likely  used to lock fixed high-frequency oscillators to stable low-frequency references to  ch06.indd   21 12/17/07   2:03:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Unlike the theoretical Dolph-  Cliehysliev pattern. the sidelobes of tlie Taylor pattern decrease outside a specified angular  region. l'he sidelobe level is uniform within the region defined by I(d/A) sin 41 < i and  decreases with increasing angle 4 for /(&A) sin 41 > ii, and where ii is an integer, d is the  aritenna dimension and 1 is the wavelength. 
 S. Cole, “Dispersion and absorption in dielectrics, I, alternating current  characteristics,” J. Phys. 
 21. pp. 59 63. 
 Sensitivity velocity control (SVC) is used when a radar must  detect aircraft and missile targets in the presence of returns from unwanted targets  such as large birds or bird flocks. The criteria to accept or reject targets is based on a  combination of the radial velocity and apparent RCS (radar cross section) of the target  returns. The desired targets may have an RCS smaller than a single bird, or possibly  FIGURE 2.92  Velocity response of clutter map ch02.indd   87 12/20/07   1:47:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Marcum, J.: A Statistical Theory of Target Detection by Pulsed Radar, Mathematical Appendix, IRE  Trans., vol. IT-6, pp. 145-267, April, 1960. 
 TRACKING CIRCUITS AND  !'# CIRCUITS LOOK AT ONLY THE SHORT RANGE INTERVAL  OR TIME INTERVAL  WHEN THE DESIRED ECHO PULSE IS EXPECTED 4HE RANGE TRACKING OPERATION IS PERFORMED BY CLOSED 
  ON THE USE OF THE AUTOMATIC IDENTIFICATION 3YSTEM !)3  IN MARINE  AIDS TO NAVIGATION v %DITION   )NTERNATIONAL !SSOCIATION OF ,IGHTHOUSE !UTHORITIES )!,!   0ARIS    h2ECOMMENDATION 2 
 Parent, “Effects of geomagnetic pulsations on the doppler shift  of HF backscatter radar echoes,” Radio Science , vol. 24, pp. 183–195, 1989. 
 (10.1) into Eq. (10.4) gives  Since S*(f) = S(- f ), we have  a3  /I(() = G,, S(f) exp [j2nf (ti - r)] df = G,s(t - t)  A rather interesting result is that the impulse response of the matched filter is the image of  the received waveform; that is, it is the same as the received signal run backward in time  starting from the fixed time t,. Figure 10.1 shows a received waveform s(t) and the impulse  response It(() of its matched filter. 
 The results show that the types of the ships can be classiﬁed in high accuracies and reveal the effectiveness of our proposed method. Keywords: synthetic aperture radar (SAR); convolutional neural networks (CNNs); deep learning (DL); ship classiﬁcation 1. Introduction Synthetic aperture radar (SAR) is an active Earth observation system that can be installed on planes, satellites, spacecraft, etc. 
 PULSE TRANSMITTER PHASE 
 ON INCIDENCE IS AT THE CENTER OF THE PATTERN AND THAT THE CHARTED 2#3 DATA ARE IN DECIBELS ABOVE A SQUARE METER AT THE TEST FREQUENCY &IGURE  CHARTS THE 2#3 OF A SHIP MEASURED AT  AND  '(Z AT HORIZONTAL  POLARIZATION 4HE DATA WERE COLLECTED BY A SHORE 
 SION IS USED !N UNCODED  
 pp. 29 33. June. 
 Clearly the efficiency of the adaptive array depends  on the number of degrees of freedom (dof) and the accuracy of receiving chan - nels (e.g., degrees of matching). There is some trade-off between accuracy and  number of channels; a system with one dof is less efficient (and requires maximum  accuracy) than a system with, say, four dof. An adaptive system with N dof can  theoretically suppress ( N – 1) jammers, realistically—as a rule of thumb— N/2 or  N/3. 
 IZATIONS EG  HORIZONTAL ;(= AND VERTICAL ;6= OR RIGHT 
 1975. Arlirigtoli, VA.  pp. 
 159^182. 9. Gray, G. 
 The elaboration of the simple range equa- tion to yield meaningful range predictions is the subject of Chap. 2. Although the range enters as the fourth power in Eq. 
 12–23, June 1953.  4. R. 
 Most frequency deviations arenotofthis simple sort. They aremore likely tobeperiodic orrandom, with asuperimposed uni- form drift. The rate ofchange offrequency can beexpressed bya Fourier spectrum and thetotal phase error determined bysuperimposing thecontributions resulting from each oftheFourier components. 
  
 (a)  (b) azimuth (samples)range (samples) 400 600 800 1000 1200740760780800820840860 azimuth (samples)range (samples) 400 600 800 1000 1200740760780800820840860 azimuth (samples)range (samples) 600 800 1000740760780800820840860 azimuth (samples)range (samples) 700 800 900740760780800820840860 azimuth (samples)range (samples) 750 800 850740760780800820840860 azimuth (samples)range (samples) 700 800 900740760780800820840860 (c)  (d) azimuth (samples)range (samples) 740 760 780 800 820 840740760780800820840860 azimuth (samples)range (samples) 740 760 780 800 820 840740760780800820840860 azimuth (samples)range (samples) 740 760 780 800 820 840740760780800820840860 azimuth (samples)range (samples) 750 800 850740760780800820840860 azimuth (samples)range (samples) 750 800 850740760780800820840860 azimuth (samples)range (samples) 750 800 850740760780800820840860 Figure 9. The two-dimensional imaging results of targets by the different methods with the velocity and acceleration errors. ( a) No Doppler parameter estimation; ( b) the basic MAM method; ( c) the IMAM method; ( d) the EMAM method. 
   PP n     ( *ENSEN  , # 'RAHAM  , * 0ORCELLO  AND % . ,EITH  h3IDE 
 #/5.4%2-%!352%3   Ó{°{Î MOUNTED ON THE AIRCRAFTS WINGTIP AS FAR APART AS POSSIBLE 4HE SIGNALS RECEIVED IN EACH  WINGTIP ANTENNA ARE REPEATED IN THE OPPOSITE WINGTIP ANTENNA  EXCEPT FOR A  n PHASE  SHIFT  WHICH IS INSERTED IN ONE LINE TO DIRECT AN INTERFEROMETRIC NULL TOWARD THE VICTIM RADAR )N EFFECT  THIS CREATES AN APPARENT CHANGE OF TARGET DIRECTION AS VIEWED FROM THE RADAR ! LARGE REPEATER GAIN IS REQUIRED TO GENERATE A HIGH JAMMER 
 J. Schmidt: Gross Errors in Height Indication from Pulsed Radar Altimctzrs  Operating over Thick Ice or Snow, Proc. IRE, vol. 
 BILITY )N THIS SECTION  SOME  OF THE KEY CHARACTERISTICS OF RAD AR CLUTTER AND ITS INFLUENCE  ON -4) RADAR DESIGN WILL BE SUMMARIZED 3PECTRAL #HARACTERISTICS   4HE SPECTRAL CHARACTERISTICS OF CLUTTER  AS DISCUSSED IN  MOST REFERENCES  IMPLICITLY ASSUMES THAT  THE RADAR TRANSMITS A  CONTINUOUS  CONSTANT 02&  WAVEFORM 4HE SPECTRUM OF THE OUTPUT OF A PULSED TRANSMITTER USING A SIMPLE RECTANGULAR PULSE OF LENGTH  S  IS SHOWN IN &IGURE   4HE SPECTRAL WIDTH OF THE SIN 5 5  ENVELOPE  IS DETERMINED BY THE TRANSMITTED PULSE WIDTH  THE FIRST NULLS OCCURRING AT A FREQUENCY OF  F  o S 4HE INDIVIDUAL SPECTRAL LINES ARE SEPARATED BY A FREQUENCY EQUAL TO THE 02&  4HESE SPECTRAL LINES FALL AT PRECISELY THE SAME FREQUENCIES AS THE NULLS OF THE -4) FILTER RESPONSE SHOWN IN &IGURE  4HUS  A CANCELER WILL  IN THEORY  FULLY REJECT CLUTTER WITH THIS IDEAL LINE SPECTRUM )N PRACTICE  HOWEVER  THE SPECTRAL LI NES OF THE CLUTTER RETURNS ARE  BROADENED BY MOTION OF THE CLUTTER SUCH AS WINDBLOWN TREES OR WAVES ON THE SEA SURFACE  AS WELL AS BY THE MOTION OF THE ANTENNA IN A SCANNING RADAR OR DUE TO PLATFORM MOTION 4HIS SPECTRAL SPREAD PREVENTS PERFECT CANCELLATION OF CLUTTER IN AN -4) SYSTEM /FTEN  IN THE PAST  THE ASSUMPTION HAS BEEN MADE THAT THE RETURNS FROM CLUTTER HAVE A  GAUSSIAN POWER SPECTRAL DENSITY  WHICH MAY BE CHARACTERIZED BY ITS STANDARD DEVIATION R V AND MEAN VELOCITY  MV  BOTH IN UNITS OF MS 5SING THIS GAUSSIAN MODEL  EACH OF THE  SPECTRAL LINES IN &IGURE  WILL BE CONVOLVED WITH THE SPECTRUM   3FFM ' FF F  E X P   
 M. Kirkpatrick: Effect of Internal Fluctuations and Scanning on Clutter Attenuation in MTI Radar, IRE Trans., vol. ANE-2, pp. 
 HALF THE  &)'52%       3PECTRAL 
 02& WAVEFORMS  THE ASSUMPTION IS MADE THAT THE NOISE COMMON TO TRANSMIT AND RECEIVE ADDS NONCOHERENTLY IN THE DOWNCONVERSION PROCESS !S A RESULT  THE COMMON DISCRETE POWER INCREASES BY  D" 4ABLE  PROVIDES THE CALCULATION FOR THE SYSTEM REQUIREMENTS FOR INDEPENDENT  AND COMMON DISCRETE LEVELS !S IN 4ABLE   A MAXIMUM CLUTTER LEVEL REQUIRING A  
 P. Home, Synchronization Aspects for Bistatic Radars, IEE Int. Radar Conf. 
 Each radiating element is usually designed to be very  broadband and is driven by a T/R channel in a typical AESA array. There are typi - cally a few thousand channels in an MFAR AESA. Each channel contains first-level  power regulation, filtering, logic, calibration tables as well as the obvious RF func - tions. 
 The standard temperature T0  is taken to be 290 K. according to the Institute of Electrical and Electronics Engineers  definition. The noise NO is measured over the linear portion of the receiver input-output  characteristic. 
 17. F. Fabry, C. 
 A modulator with an internal impedance of t 50 ohms will result in  both current and voltage variations as a function of frequency when used with the above CF A,  but the power output varies only 1 dB. Thus it does not matter significantly to the modulator  designer whether the CF A is of the backward-wave or the forward-wave type as long as  cathode pulsing is used with either a line-type modulator or a constant-current hard-tube  modulator.  Electron emission in high-power crossed-field amplifiers can take place by cold-cathode  emission without a thermally heated cathode. 
 A low sidelohe antenna might  have to be 20 to 30 percent larger than a conventional antenna to achieve the same beam width.  Aperture efficiency. The aperture efficiency is the ratio of the actual antenna directivity to the  maximum possible directivity. 
 (a)Photograph ofscope. @)Sketch from map. 621. 
 DOPPLER 34!0 ARCHI 
 From which, complete geometric features of the target can be seen clearly. The information entropy is used to evaluate the effects of image fusion. Information entropy in Figure 15a,b are 6.1819 and 6.1046, and information entropy in Figure 15c is 6.6635. 
 Several meteorological conditions may lead  to the formation of surface-based ducts. Over the ocean and near land masses, warm, dry continental air may be advected  over the cooler water surface. Examples of this type of advection are the Santa Ana  of southern California, the Sirocco of the southern Mediterranean, and the Shamal of  the Persian Gulf. 
 3 cm ASV radars were also developed during the war for the Fleet Air Arm (FAA) and for CoastalCommand attack aircraft. In association with ASV Mk. I and II, a system of homing beacons and IFF interrogators had been developed on wavelengths around 1.5 m. 
 Obviously, selecting PRFs in real time requires  several rules to get close to a final set. This is followed by small iterations to pick the  optimum set. For medium PRF, both range and velocity blind zones are important.52,65  First, the software must pick a central PRF about which all the other PRFs are devia - tions to fill out the desired visibility criteria. 
 The tradeoff which has to be sought between the accuracy of weights es- timation and the reaction time of the adaptive system. 8. The quantization and processing accuracy in the digital implementation. 
 Therefore. overthegrazinganglesofusualinterest. aradar which IIIlistdetecttargetsoverlandhasamoredifficult taskthanonewhichmustdetect targetsovcrthesea.Eventhougharadaratseamightnotbebothered byseaclutter,nearby landcluttercanbesolargethatitcanentertheradarviatheantenna sidelobes anddegrade performance. 
 In general, conical scan is performed during the  search mode of most tracking radars.  The Palmer scan is suited to a search area which is larger in one dimension than another.  The spiral scan covers an angular search volume with circular symmetry. 
 MITTER PERFORMANCE BY ALLOWING A WIDE VARIATION IN PARAMETERS PULSE WIDTH  PULSE REPETITION FREQUENCY  PULSE AGILITY  AND PULSE 
 4.14c.  of large clutter returns can effectively appear as a large step input to the filter with the result  that severe ringing is produced in the filter output. The ringing can mask the target signal until  the transient response dies out. 
 A cornparison of these five models for a false-alarm number = 10' is shown in Fig. 2.22  for 11 = 10 hits integrated. When the detection probability is large, all four cases in which the  targct cross section is not constant require greater signal-to-noise ratio than the constant cross  section of case 5. 
 The computer allows the radar  to utilize its resources elfectively by scheduling the execution of the various functions so as  to perform the more important tasks first.  A multifunction array radar rnight be called upon to perform the following tasks:  Search of a specified volurne of space at a specified rate, and the detection of targets.  Track itritiatiotl, or transition to track, after a new detection is established. 
 !RRAY 3YSTEMS AND 4ECHNOLOGY    "OSTON 53!   /CTOBER n    PP n  7 +UHN  7 3IEPRATH  , 4IMMONERI  AND ! &ARINA  h0HASED 
 Interlacing of subarrays can  reduce the grating lobes. FIGURE 13.26  Phased array using subarrays with time delay ch13.indd   43 12/17/07   2:40:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 [ CrossRef ] 13. Fornaro, G.; Guarnieri, A.M.; Pauciullo, A.; De-Zan, F. Maximum likelihood multi-baseline SAR interferometry. 
 Even ifthe ground returns had been constant, much the same bandwidth would have been needed because ofmodulation due to scanning. The rest ofthe curve was then made asnarrow aspossible. This turned outtobeabout 200cycles atthe3-db point. 
 Though the function cannot be explicitly represented, we can show it numerically in a ﬁgure and obtain some useful information. Take the data from ionosonde and PolSAR in Table 2as an example. The Bcosθas a function of altitude could be obtained from the ambient magnetic ﬁeld of PALSAR, as shown in Figure 3a. 
 The only requirement that must be met is that the combination of the amplification and the total filtering is such that the amplitude of the unwanted signals nowhere approaches the saturation level. Doppler Filter Banks. Ideally no nonlinear operation occurs in the signal processing and amplification. 
 This pattern is repetitive, and the  locations of the adjacent grating lobes at angles q 1 and q 2 are separated by p (s/l)   (sin q 1 − sin q 2) = p . FIGURE 13.5  Linear array with N radiators uniformly spaced by a distance s ch13.indd   11 12/17/07   2:39:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The con - sequence, of course, is that the effective PRF is reduced by the same factor n. This  practice is seldom acceptable for space-borne SARs, because it leads to azimuth ambi - guities unless the doppler spectrum is limited prior to PRF reduction. Ambiguities . 
 BAND EXTENDED INTERACTION KLYSTRON FOR  THE #LOUD3AT PROGRAM v )%%% 4RANS  VOL %$ 
 Note that there is zero response to stationary targets and also to targets at ±89, ±178, ±267,...knots. These speeds, known as blind speeds, are where the targets move O, 1Xz, 1, 11/2,...wavelengths between consecutive transmitted pulses. This results in the received signal being shifted precisely 360° or multiples thereof between pulses, which results in no change in the phase-detector output. 
 The noise or clutter fluctuations that appear at the  output of a logarithmic receiver are not symmetrical since the large amplitudes are suppressed  due to tl~c nati~re of the logarithmic cl~aracteristic. To make the output more like that of a  liriear receiver, tlie log-FTC may he followed by an amplifier with the inverse of the logarith-  ~riic cliaracteristic (antilog). This restores the contrast of the display and eliminates the loss in  detectability associated with the logarithmic characteristic. 
 SCALE DYNAMIC  SEA 
 ICE    $ATA FROM RADAR MISSIONS ARE AVAILABLE THROUGH  .!3!S 0LANETARY $ATA 3YSTEM &LIGHT 3YSTEMS  6ENERA 
 Some authors, like Marcum, prefer to use the false-alarm numbi..:r  instead of the false-alarm probability. On the average, there will he one false decision out of 111  possible decisions within the false-alarm time Tra. Thus the average number of possible 1.kci­ sions between false alarms is defined to be n 1. 
 The echo signal received at the radar is  sin [2n/o(r - 7')]. If tlie transrnitted and received signals are compared in a phase detector,  the orttpilt is jwoportio11:il to the phase difference between the two and is A4 = 2?f0 T =  4?lo Rlc. l'llc phase differerice may therefore be used as a measure of the range, or  However, the measurement of the phase difference A4 is unambiguous only if A4 does not  exceed 2n radians. 
   PP n  *ULY   ( - &INN  h! #&!2  DESIGN FOR A WINDOW  SPANNING TWO CLUTTER FIELDS v  )%%% 4RANS  VOL !%3 
 ‘Flip-flop,’ 93 ef seq.  Flyback suppression, 80-81  France, pioneer radar in, 19  Frequencies, common radar,  48  Frequency difference systems,  164  ‘GATING’ CIRCUITS, 97  Gee, 144 et seg., 170  G-H, 154  ‘Grass,’ 46  H2S, 135 et seg.) 170  Hanbury-Brown, R., 26  Heil tubes, 117, 120 et seq.  Huxley, Dr L., 29  IFF, 25, 157  Jones, F. 
 This approach allows for full electronic scanning of the beam. A network of 400-MHz wind profilers in the cen- tral United States is also expected to use solid-state transmitters, but electronic scanning will not be possible. The meteorological community is excited about these devices because of their ability to measure winds continuously. 
 GENERATED REFLECTIONS  AND CONTROL CIRCUITRY HAS BEEN INCLUDED TO SWITCH OFF MODULES IN THE EVENT OF COOLING 
 6.26  6.5 Reflector Antenna Analysis  ....................................  6.27  6.6 Shaped-Beam An tennas  ........................................  6.30  Gain Estimation  ................................................. 
 adding Stepwisegate control tilggu Modulatw pulse I I T!mingpulaa III1IIIIIII1IIII Internalsel~~ngpulse~ Pulsesalacting gata n n Delayed-sweep trigger I I Delayedsweep Interpolation marker I 1 FIG. 13.40.—Discrete sweep delay. problem isthat ofselecting theproper pulse. 
 MENTS ON BASIC RADAR PERFORMANCE  NORMALLY BASED ON OPPORTUNISTICALLY TESTING THE RADAR OVER THE SEA AND IN PRECIPITATION IN A VARIETY OF SITUATIONS *UDGMENTS ON PERFORMANCE CAN  THEREFORE  BE QUITE SUBJECTIVE AND ARE NATURALLY AFFECTED BY THE CONDITIONS ACTUALLY ENCOUNTERED DURING THE TESTS #OST CONSIDERATIONS CAN SEVERELY LIMIT THE LENGTH OF TEST PROGRAMS AND THEREBY THE RANGE OF SCENARIOS USED 2ADARS UNDER  TYPE APPROVAL ARE TYPI 
 The processes that constitute on-axis tracking include ( 1) the use of adaptive tracking  whose output updates a stored prediction of the target trajectory rather than control the  antenna servo directly, (2) the removal by prior calibration of static and dynamic system  biases and errors, and (3) the use of appropriate coordinate systems for filteriqg (smoothing)  the target data.  The radar's angle-error signals are smoothed and compared to a predicted measurement  based on a target-trajectory model updated by ·the results of previous measurements. (Prior  knowledge of the characteristics of the trajectory can be incorporated in the model, as, ror  example, when the trajectory is known to be ballistic.) If the difkrence between the prediction  and the measurement is zero, no adjustment is made and the antenna mount is pointed  according to the stored prediction. 
 If the maximum target velocity to be observed is ±Vrmax, then the minimum value of PRF, fRmin, which is unambiguous in velocity (both magnitude and doppler sense, i.e., positive and negative), is /Jlmin = 4VTmBX/X. (17.1) However, some pulse doppler radars employ a PRF which is unambiguous in velocity magnitude only, i.e.,fRmin = 2Vrmax/X, and rely on detections in multi- ple PRFs during the time on target to resolve the ambiguity in doppler sense. These types of radars can be considered to be in the high-PRF category if the older definition of high PRF (no velocity ambiguity) is extended to allow one ve- locity ambiguity, that of doppler sense. 
 Sensors 2019 ,19, 1154 Image entropy and IC value are the two criteria to assess the image quality. The convergences of the two criteria versus the number of iterations are depicted in Figure 8. As the number of iterations increases, there has been decrease in entropy and increase in IC. 
 AP-8, pp. 490-495, September,  1960.  86. 
 TER  SUCH AS -EDIUM 
 POLARIZATION RETURNS IN FASTER 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation. 
 46. Hagler, T.: Building Large Structures in Space, Astronaut. Aeronaut., vol. 
 For instance, the changing  frequency of a linearly frequency-modulated pulse is distributed along the pulse and thus  identifies each segment of the pulse. By passing this modulated pulse through a delay line  whose delay time is a function of the frequency, each part of the pulse experiences a different  time delay so that it is possible to have the trailing edge of the pulse speeded up and the leading  edge slowed down so as to effect a time compression of the pulse.  The pttlse co~npres.sion rario is a measure of the degree to which the pulse is co.mpressed. 
 does not sharply divide the regions of propagation and no propagation, so that radiation  whose wavelength is several times the "cutoff wavelength" may be affected by tile dirct.  A duct is produced when the index of refraction decreases with altitude at a rapid rate. if  file index of refraction [Eq. 
 A 1-iterature Survc).  Georgia I~lsritlrtr 01' Tc~ch~~oloy!~ Rutlar a11rl I~l.srrir~~rrnrario~~ Lahoruror~: Atlanta, Ga., sponsored by  Western Collon Research Laboratory, 1J.S. Dcpt. 
 BP result is used as the reference. It is shown that the result of LS-CS-Residual is highly overlapped with the results of BP . The intensities of CS and debiased-CS are less than BP and LS-CS-Residual. 
 6. Steinberg, B. D.: High Angular Microwave Resolution from Distorted Arrays, Proc. 
 R. Gladman: Further Observation on the Detection of Small  Targets in Sea Clutter, The Radio and Electronic E11gi11ecr, vol. 45, pp. 
 CAL APPLICATIONS AND REQUIREMENTS n 4HIS CHAPTER WILL DEAL PRINCIPALLY WITH AIRBORNE  APPLICATIONS  ALTHOUGH THE BASIC PRINCIPLES CAN ALSO BE APPLIED TO THE SURFACE 
 After maximizing the signal-to-noise ratio in the IF amplifier, the pulse modulation is  extracted by the second detector and amplified by the video amplifier to a level where it can be  Antenna Transmitter  Low-noise  RF  amplifier Pulse  modulator  IF amplifier  (matched filter)  Figure 1.2 Block diagram of a pulse radar. 2d  detector Video  amplifier Display . 6 INTRODUCTION TO RADAR SYSTEMS  ,  -~  (al (I.)  -0  -~ a. 
 Noise figure of networks in cascade. Consider two networks in cascade, each with the same  noise bandwidtt~ B, but with dimerent noise figures and available gain (Fig. 9.1). 
 59. Kalmus. H. 
 15, pp. 815–826, 1980. 41. 
 But in many cases the value will betoo large for this system tobeuseful, Specifically, the maximum beat frequency may bewritten asfr(r/6r) so that, for example, 1per cent range accuracy and f,=10cps gives ~~=1000 CPS, wfich may becompared with adoppler frequency of 894 cpsfor10cmand 100 mph. 6.10. Alternative F-m Ranging System .—Another scheme ofthe f-mtype which isdesigned towork onmultiple targets and inthepresence ofclutter may beunderstood byreference toFig. 
 The passive TR-limiter or the diode  limiter has replaced the protector TR. Such devices are known as receiver protectors. Receiver  protectors also serve to protect against power reflected by mismatches at the antenna. 
 CONVOLUTION AND POINT 
 ERAL LOCATIONS IN THE ARRAY AND THEN CORRECT THE PHASE COMMANDS TO THE PHASE SHIFTERS £Î°£äÊ -"  -// 
 Such coherent change detection is a standard technique in  the field of space-based SAR interferometry, reviewed in the following section. Exact- repeat orbits are standard for most radar altimeters, but for geophysical reasons, not  for mutual coherency. Sun-synchronicity presents its own problems for ocean-sensing  altimeters. 
 The FM-CW radar principle is used in the aircraft radio altimeter to  measure height above the surface of the earth. The large backscatter cross section and the  relatively short ranges required of altimeters permit low transmitter power and low antenna  gain. Since the relative motion between the aircraft and ground is small, the effect of the  doppler frequency shift may usually be neglected. 
 28.VonAulock,W.H..andCE.Fay:"LinearFerriteDevicesforMicrowave Application." Academic Press,NewYork,1968. 29.Clarricoats, P.J.8.:"Microwave Ferrites," JohnWileyandSons,NewYork,1961. 30.Ince,W.J.,andD.H.Temme: PhasersandTimeDelayElements. 
 SHEET DESIGN  AS SUGGESTED IN &IGURE  4HE PRICE PAID FOR THIS BANDWIDTH EXPANSION IS A MUCH THICKER  BULKIER MATERIAL THAT TENDS TO BE IMPRACTICAL FOR TACTICAL MILITARY TARGETS ,IKE THE 3ALISBURY SCREEN  THE  $ØLLENBACH LAYER IS ALSO A SIMPLE ABSORBER 4HE MATE 
 L., and A. W. Rudge: Adaptive Control of a Flexible Linear Array. 
 The results show that the curve of the top-hat is smooth because it is isotropic. Since the dihedral and trihedral are both anisotropic, the high scatterings are concentrated in a limited 250. Sensors 2019 ,19, 346 range. 
 FIELD PATTERNS &IRST  CONSIDER THE CALCULATION OF THE REFLECTOR SURFACE CURRENTS )T IS ASSUMED THAT  THE FIELD FROM THE FEED THAT IS INCIDENT ON THE REFLECTOR HAS A SPHERICAL WAVEFRONT WITH AMPLITUDE TAPERING DEFINED BY THE FEED PATTERN 3O  AS A FIRST STEP  THE FEED IS MATHEMATICALLY MODELED TO DETERMINE THE INCIDENT FIELD AMPLITUDE AND PHASE AT THE REFLECTOR SURFACE $IFFERENT MODELS ARE APPLIED DEPENDING ON THE CHOICE OF FEED USED IN THE DESIGN EXAMPLES INCLUDE WAVEGUIDE FEED HORNS  MICROSTRIP PATCHES  DIPOLES  ETC 3OMETIMES THE FEED MODEL WILL INSTEAD EMPLOY MEASURED FEED PATTERNS IF SUCH DATA IS AVAILABLE !LL MODELS MUST BE NORMALIZED TO SOME PRESCRIBED RADIATED POWER LEVEL  EG   WATT &IGURE  SHOWS A TYPICAL WAVEGUIDE FEED HORN MODEL AND ITS ASSOCIATED LOCAL COORDINATE SYSTEM "ASED ON AN APPROPRIATE APPLICATION OF EQUIVALENCE PRINCIPLE AND THE INDUCTION  THEOREM  n THE CURRENTS INDUCED ON THE REFLECTOR CAN BE DETERMINED FROM THE FEED  &)'52%   7AVEGUIDE FEED HORN MODEL  AND COORDINATE SYSTEM. £Ó°ÎÓ  2!$!2 (!.$"//+  ( 
 W. Shrader: lnterclutter Visibility in MTI Systems, IEEE EASCON '69  Cm1re11tio11 Record. pp. 
  P 4    62 K  COS C 2  
 8.4.  The other is a receive-only method that uses a receiving array with mixers and local  oscillators ( LOs), arranged so as lo provide N separate receiving beams fixed in space  (Fig. 8.29). 
   !PRIL    $ + "ARTON  2ADAR 3YSTEM !NALYSIS  %NGLEWOOD #LIFFS  .* 0RENTICE 
 In practice this is only an approxima-  rir)ll. Electroniagnetic radiation doesn't always respect such an assul~lption. C'irrretlt ill orle  element will affect the phase and amplitude of the currents in neighboring elements. 
 It should be given consideration, along with other  possible radar techniques, in those applications where some inherent characteristic may he a  desirable attribute or when the application does not require complete target information. But  as a means for the general detection and location of targets, it is overshadowed hy)its offspring,  the monostatic radar. ··  14.7 MILLIMETER WAVES AND BEYOND  Radar has been applied primarily in the microwave portion of the electromagnetic spectrum,  with Ka band (35 GHz) representing the nominal upper limit for traditional radar applica­ tions. 
 The defocusing of SAR image causes the larger phase error, which has the impact on the accuracy of the DEM and further aﬀects the imaging quality. The defocusing can cause two types of phase error. The ﬁrst is the random phase error due to the decrease of the SAR image’s signal-to-noise ratio (SNR). 
  A   y K O A  WHEN AK  4HE ROLL 
 The helix has been operated at high average power by passing cooling fluid through a  helix constructed of copper tubing.43 The bandwidth of this type of fluid-cooled helix TWT  can he almost an octave, and it is capable of several tens of kilowatts average power at L band  with a duty cycle suita hie for radar applications.  t\ popular form of slow-wave structure for high-power TWTs is the coupled-cat'ity  circuit. 7· 11 ft is not derived from the helix as are the ring-bar or ring-loop circuits. 
 Carrara, L. Joyce, and D. Franczak, “Moving target algorithms for SAR data,”  IEEE Transactions on Aerospace and Electronic Systems , vol. 
 not,itmaybenecessary toprovide additional filtering toattenuate undesired cross­ modulation frequency components. Automatic gaincontrol.9- 1 ITheecho-signal amplitude atthetracking-radar receiver will notbeconstant butwillvarywithtime.Thethreemajorcausesofvariation inamplitude are (1)theinverse-fourth-power relationship between theechosignalandrange,(2)theconical­ scanmodulation (angle-error signal), and(3)amplitude fluctuations inthetargetcross section. Thefunction oftheautomatic gaincontrol(AGC)istomaintain thed-clevelofthe receiver outputconstant andtosmooth oreliminate asmuchofthenoiselike amplitude fiuctuations aspossible without disturbing theextraction -ofthedesirederrorsignalatthe conical-scan frequency. 
 The extremely high PSLR and ISLR indicate that the scintillation effect will lead to serious expand of the azimuth mainlobe and further not only degenerate the azimuth resolution but also induce the peak loss. Compared with the azimuth imaging result, the distortion in range is not as serious as that in azimuth. The asymmetric sidelobe can be seen in Figure 11b mainly due to the power leakage of azimuth mainlobe. 
 This can be seen (Figure 13.30 a) to amount to  211 42 222π λπ λf r fr fr f+ −( )= −  +    …  With a sufficiently large focal length, the spherical phase front may be approxi - mated by that of two crossed cylinders, permitting the correction to be applied simply  with row-and-column steering commands. Correction of a spherical phase front with the phase shifters reduces peak phase- quantization lobes (Section 13.6). Space problems may be encountered in assembling  an actual system, especially at higher frequencies, because all control circuits have to  be brought out at the side of the aperture of the lens array. 
 This detector can be divided into three parts: a ranker, an integrator (in this case a two-pole filter), and a threshold (decision pro- cess). A target is declared when the integrated output exceeds two thresholds. The first threshold is fixed (equals JJL + T}IK in Fig. 
 15. Anand, Y., and W. J. 
 Sidelobes can severely limit resolution when the relative magnitudes of received signals are large. Paired Echoes and Weighting. A description of the weighting process is facilitated by the application of paired-echo theory.36"39 The first seven entries in Table 10.7 provide a step-by-step development of Fourier transforms useful in frequency and time weighting, starting with a basic transform pair. 
 A rectangular display in which a target appears as a centralized blip when the radar antenna is  aimed at it. Horizontal and vertical aiming errors are respectively indicated by the horizontal and  vertical displacement of the blip.  G-Scope. 
 1.32 138. April. 1956. 
 Phys. ZAMP 1958 ,9, 543–553. [ CrossRef ] 22. 
 ATIC APPROACH TO FILTER DESIGN IS DESIRABLE )F A DOPPLER FILTER DESIGN CRITERION IS CHOSEN THAT REQUIRES THE FILTER SIDELOBES OUTSIDE THE MAIN RESPONSE TO BE BELOW A SPECIFIED LEVEL IE  PROVIDING A CONSTANT LEVEL OF CLUTTER SUPPRESSION   WHILE SIMULTANEOUSLY MINIMIZ 
 The effect of a filter response on range or time sidelobes  can be seen by taking the filter impulse response h(t) and adding to this a delayed  impulse response 20log10(a) dB below the main response to produce the modified  response h'(t), which is given by  h'(t) = h(t) + a h(t−T0) (6.18) Using the property of time shifting of the Fourier transform, the resultant frequency  response is given by  ′ = +−H H e Hj T( ) ( ) ( ) w w a ww0  (6.19) Thus, for small values of a, the resulting magnitude and phase response is that of the  original filter modified by a sinusoidal phase and amplitude modulation as given here:  | ( ) || ( ) |( c os( ) ) ′ = + H H T w w w 10 α  (6.20)  ∠′ = ∠ − H H T ( ) ( ) sin( ) w w a w0 (6.21) Therefore, if there are n ripples across the filter bandwidth B, the range sidelobe  occurs at time T0 given by  T0 = n/B (6.22) Assuming a compressed pulse width of 1/B, values of n < 1 will put the range  sidelobe within the main lobe of the target return, resulting in a distortion of the  mainlobe response. Channel Matching Requirements.  Radar receivers with more than one  receiver channel typically require some degree of phase and amplitude matching  or tracking between channels. 
 "AND ENGINEERING DEVELOPMENT  MODEL ACTIVE PHASED ARRAY MOUNTED IN NEAR 
  
 V . Ryzhkov, and J. Straka, “Cloud micro - physics retrieval using S-band dual polarization radar measurements,” Bull. 
 Sci. Researclt, sec. B, vol. 
 Allen, “Interferometric synthetic aperture radar,” IEEE GRS Society Newsletter , pp. 6–13,  November 1995. 43. 
 GETS  AND THUS MOVERS COULD BE  DETECTED AND ANALYZED ,ATER RES EARCHERS EG  !DAMS  ET AL   USED TWO ANTENNAS DISPLACED VERTICALLY ON THE PLATFORM SO THAT THE RECEIVED  ECHOES FROM A TARGET ABOVE THE SURFACE ASSUMED FLAT  WOULD BE DIFFERENT FROM THE CORRESPONDING ECHOES FROM A TARGET ON THE SURFACE  AND THUS TAR GET HEIGHT COULD BE ESTI 
 Beam shaping may also be employed to increase the target-to-clutter ratio in some cases.  A target at high elevation angles competes with surface clutter at low angles. Increasing the  antenna gain at high angles but not At low angles will therefore improve the target echo with  respect to the  Figttre 7.27 Antcnrla clcvatiorl pattern for a long-range air-search radar lo achieve high-angle coverage  when S'TC is employed. 
 Antenna Beam Scanning.  For most radar applications, the trade or choice  between a reflector antenna and a direct radiating phased array is typically driven by  factors relating to scan rate, scan volume, and cost. Reflector antennas are typically  employed in a radar when (1) slower scan rates are sufficient and mechanical scan - ning suffices, and/or (2) a very high gain (electrically large) aperture is required and a  phased array, i.e., an electronic scanning array (ESA), is cost prohibitive, and/or (3) the  required scan volume is limited and can be satisfied via use of an array-fed reflector. 
 ITY BY ITS COMPLEX VECTOR COUNTERPART     4HUS  WHEN EITHER ( OR 6 POLARIZATIONS ARE  INCIDENT ON A SCATTERING ELEMENT  BOTH POLARIZATIONS ARE BACKSCATTERED ACCORDING TO  % %33 33% %(" 6"(4 64§ ©¨¶ ¸· § ©¨¶ ¸·§ ©¨¶ ¸·(( (6 6( 66    WHERE THE SUPERSCRIPT  " DENOTES THE FIELD COMPONENTS REFLECTED BACK TOWARD THE RADAR  4HE NEW TERMS OF INTEREST REPRESENT THE SCENES   r  SCATTERING MATRIX  AN ARRAY OF FOUR  COMPLEX NUMBERS %ACH ELEMENT IN THIS BACKSCATTERING MATRIX EXPRESSES THE MAGNI 
 One of  tile nletliods sometimes suggested for increasing the first blind speed is to transmit two carrier  freqileticies ,lo and l;, + A/'and extract the difference frequency At for MTI processing. TIle  resulting blind speeds will be tlie same as if the radar transmitted the difference frequency  rather than tlie carrier. For example, if Af = O.lfo, the first blind speed corresponding to the  difference frequency is 10 times that of an MTI radar at the carrier frequencyfo :Thus, it would  seern that the advantages of a VHF or UHF MTI might be obtained with radars operating at  the higher microwave frequencies. 
 AIR SEARCH AND TRACK TO PROTECT BOTH OF THEM&)'52%  4YPICAL AIR 
 When this isthecase, therange indicated isthat ofthestrongest target. Thk difficulty may bereduced asdesired byreducing thelength ofthe transmitted puJse, bycorrespondingly increasing the number of filter bands, and soincreasing the complexity. Since the general objects ofthis system aremuch the same asthose ofthe MTI system described inChap. 
 59-64, September, 1972.  35. Whicker, L.: Selecting Ferrite Phasers for Phased Arrays, Micro\\~ti~.es, vol. 
 MADE  OBJECTS . 
 Narrow beam widths are impor­ tant for high-resolution imaging radar and to avoid multipath effects when tracking low­ altitude targets. The short wavelengths of millimeter waves are also useful when exploring  scattering objects whose dimensions are comparable to the millimeter wavelengths, such as  insects and cloud particles. These are examples of scatterers whose radar cross sections are  greater at millimeter wavelengths than at microwaves since they are generally in the resonance  region (Fig. 
 With wind  shear, the doppler spectrum from chaff can have a wide spectral width (unless the eleva - tion beamwidth is very narrow as might occur with tri-dimensional radar with stacked  beams in elevation38) so that it is difficult to cancel moving chaff echoes. A pulse dop - pler radar has a better chance, but it has problems of its own because of the foldover of  the clutter that might occupy a large range extent. Coherent doppler processors might require relatively large amounts of pulses (e.g.,  more than 10), which must be transmitted at a stable frequency and PRF. 
 A  similar design concept is used for the electro-optical (EO) sensors, stores management,  FIGURE 5.3  MFAR merged with other sensors ( adapted2) ch05.indd   3 12/17/07   1:26:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 
 J. Earth Syst. Sci. 
 Character ofOTHradar.Thefactorsaffecting thedesignofanHFOTHradarareslightly different thanthoseaffecting conventional microwave radar.Thisisillustrated bythesimple radarequation commonly usedinOTHradaranalysis, whichis 4PavG,G,i2(JF;TcR=------- (4n)3No(SjN)Ls whereR=range Pav=average power G,=transmitting antenna gain. 6, = receiving antenna gait1  A - wavelength  o = larget cross section  F, = factor to account for the one-way propagation effects  T, = coherent processing time  No = receiver noise power per unit bandwidth  (SIN) = signal-to-noise (power) ratio  L, = system losses  The transmitting and receiving antenna gains are shown separately in Eq. (14.22) since it  is sorrletinles convenient in OTH radar to have separate antennas for these two functions. 
 1.Radar.I.Title.II.Series. TK6575.s477 1980621.3848 79-15354 ISBN0-07-057909-1 Whenordering thistitleuseISBN 0-07-066572~ 9 PrintedinSingapore. CONTENTS  Preface  1 The Nature of Radar  1.1 lntroductiorl  1.2 *l'lle Sirnple Fortn of the Kadar Equatiorl  1.3 Radar Hlock Diagram and Operation  1.4 Radar Frequencies  1.5 Radar Dcvcloprnent Prior to World War I1  1.6 Applications of Kadar  References  The Radar Equation  Prediction of Range Performance  Mirlimurn Detectable Signal  Receiver Noise  Probability-density Functions  Signal-to-noise Ratio  Integration of Radar Pulses  Radar Cross Sectiorl of Targets  Cross-section Fluctuations  Transmitter Power  Pulse Repetition Frequency and Range Ambiguities  Antenna ~aramete'rs  System Losses  Propagation Effects  Other Consideratiorls  Refererlces  3 CW and Frequency-Modulated Radar  2.1 Tile Iloppler Effect  3.2 CW Radar  3.3 Frequency-modulated CW Radar  CONTENTS Preface IX 1TheNatureofRadar 1 1.1Introduction 1 1.2TheSimpleFormoftheRadarEquation 3 1.3RadarBlockDiagram andOperation 5 1.4RadarFrequencies 7 1.5RadarDevelopment PriortoWorldWarII 8 1.6Applications ofRadar 12 References 14 2TheRadarEquation 15 2.1Prediction ofRangePerformance 15 2.2Minimum Detectable Signal 16 2.3Receiver Noise 18 2.4Probability-density Functions 20 2.5Signal-to-noise Ratio 23 2.6Integration ofRadarPulses 29 2.7RadarCrossSectionofTargets 33 2.8Cross-section Fluctuations 46 2.9Transmitter Power 52 2.10PulseRepetition Frequency andRangeAmbiguities 53 2.11Antenna Parameters 54 2.12System Losses 56 2.1JPropagation Effects 62 2.14OtherConsiderations 62 References 65 3CWandFrequency-Modulated Radar 68 3.tTheDoppler ElTect 68 3.2CWRadar 70 3.3Frequency-modulated CWRadar 81. 
 OF 
 Interactions.  Relatively strong echoes can occur when a pair of target surfaces are  oriented for a favorable bounce from one surface to another and then back to the radar,  as in the interaction between the fuselage and the trailing edge of the right wing shown  ch14.indd   3 12/17/07   2:46:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Interpolating target angles within the beam is accomplished, as shown in Fig. 18.17, by comparing the phase of the signals from the antennas (for simplicity a single-coordinate tracker is described). If the target were on the antenna boresight axis, the outputs of each individual aperture would be in phase. 
 Provision forversatility, unless ingeniously made, may cost heavily inincreased complexity, size, orweight; further, theutility ofthesetfor 588. SEC. 151] INTRODCCTIO,\- 589 theprincipal application may suffer. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 In Figure 2.30, the improvement factor of an MTI using the optimum weights  is compared with the binomial coefficient MTI for different values of the relative  clutter spectral spread and shown as a function of the number of pulses in the CPI.  These results again assume a gaussian-shaped clutter spectrum. 
 When energy is incident  normal to the array, each element receives the same phase independent of frequency.  When energy is incident from some angle other than normal, the phase difference from  the planar phase front to each element is a function of frequency and most phased  arrays with phase shifters become frequency-dependent. This same phenomenon can  be viewed in the time domain. 
 If there is a minimum target range, the response is also cut off at the  low-frequency end, to further reduce the extraneous noise entering the receiver.  Another method of processing the range or height information from an altimcter so as to  reduce the noise output from the receiver and improve the sensitivity uses a narrow-bandwidth  low-frequency amplifier with a feedback loop to maintain the beat frequency constant. 30·34  When a fixed-frequency excursion (or deviation) is used, as in the usual altimeter, the heat  frequency can vary over a considerable range of values. 
 7. 12  can reduce aperture blocking. The subreflector consists of a horizontal grating of wires, called  a transrejlector, which passes vertically polarized waves with negligible attenuation but rctlects  the horizontally polarized wave radiated by the feed. 
 ,#%  +  +"  -( +"  -( +"    
 Ê 
 antennaReference signal Figure3.11Blockdiagram ofFM-CW radar. Ideally.theisolation between transmitting andreceiving antennas ismadesufficiently largeso astoreducetoanegligible levelthetransmitter leakagesignalwhicharrivesatthereceivervia thecoupling between antennas. Thebeatfrequency isamplified andlimitedtoremoveany amplitude fluctuations. 
 RESOLUTION RADAR COMBAT 
 422–427, July 1966. 82. C. 
 In antenna design, aperture taper is used to lower sidelobes.  The modest resultant loss and increased beamwidth is the price and one is usually  willing to pay to obtain the desired sidelobe level. The loss associated with aperture  taper is accounted for in the taper efficiency. 
 STATE HIGH VOLTAGE RADAR MODULATORS v PRESENTED AT   0ULSED 0OWER #ONFERENCE !VAILABLE FROM $4) )NTERNET SITE WWWDIVTECSCOM   + * ,EE  # #ORSON  AND ' -OLS  h!  K7 SOLID 
 BIT !$# NEVER PROVIDES EXACTLY . D" OF 3.2  DUE TO !$# 
 The radar engineer should not simply compare the particular differences between  a solid-state transmitter and a vacuum tube transmitter when determining what type  of RF power source to use in any particular application. The choice between the two  should be made by comparing a radar system designed to effectively use solid state  and a radar system designed to effectively use vacuum tubes. Assuming the solid state  and vacuum tube radars are designed to provide identical performance for the desired  application, then the choice should be based on comparing cost, size, weight, reliabil - ity, maintainability, and any other system requirement that is important for decision  making. 
 Thecomparison hetween thetwoisshowninFig.2.29asafunction ofthecollapsing ratio (111+II)ill.Thedifference betweenthetwocasescanbelarge.Asthenumberofhits"increases, thedifference hecomes smaller.. Figure 2.29 Collapsing loss versus collapsing ratio (m + 11)/11, for a false alarm probability of and a  detection probability of 0.5. (From Trlr~lk," colrrtesy Proc. 
 I). D.: The Measurement and lriterpretation of Antenna Scattering, Proc. IRE, vol. 
 Since about 10°ofthe 90°arelust in switching, wecan think oftheparallel-plate region aseffecting an8-to-l optical reduction from the 80° scan ofthe broad-beamed primary horn tothe 10°scan ofthevery sharp antenna beam. The transformation ofthe moving feed horn into thescanning beam ismade bymeans oftwo double-curved bends CCand DDintheparallel plates (Fig. 9.26). 
 Itmust bepossible toobtain two tothree times the mixer current that will actually beused. When restarting acorrectly tuned oscillator, itmaybe necessary tovary thereflector voltage slightly upand down tocause the echo box tolock in. Amicrowave discriminator circuit developed byR.V.Pound’ gives promise ofovercoming many ofthe difficulties ofthe simple echo-box stabilizing arrangement. 
 The extent of the sea returns (sea clutter) were also recorded for the ‘optimum gain and contrast settings ’. Table 7.4shows the minimum (downwind) and maximum (upwind) extents of the clutter reported from the trials. Again, thereresults were quite subjective but show a clear variation between upwind and downwind directions and the increase in sea return with aircraft height and sea roughness. 
 Bertsekas, “The auction algorithm for assignment and other network flow problems: A tuto - rial,” Interfaces , vol. 20, pp. 133–149, 1990. 
 The second advantage of shorter wavelengths is that even a relatively smooth  sea, such as sea state 1, has wave heights of many wavelengths and appears rough,  resulting in a smaller reflection coefficient. This is observed in Figure 9.28 to give  small multipath errors. The 8-mm-wavelength monopulse capability may be effec - tively combined with a lower microwave band as described in Section 9.6 to take  advantage of the complementary features of both bands. 
 53. Harrington, J. V.: An Analysis of the Detection of Repeated Signals in Noise by Binary Integration,  IRE Trans., vol. 
 The spotlighted scene is a parking lot in an urban environment. The scene consists of numerous civilian vehicles and reﬂectors. In this experiment, the HH polarization data are used. 
 Two threshold levels are established  wit11 a gray region in between. If the output is definitely below the lower threshold, noise alone  is snit1 to hc prcscrlt. If the upper tl~rcshold is exceeded, the signal is declared to be present  along with the noise. 
 SPHERIC CONDITIONS )N THIS EXAMPLE  A SINGLE IONOSPHERIC LAYER IS CONSIDERED .ORMALLY  THERE ARE TWO OR THREE DISTINCT LAYERS SUCH THAT SIGNALS MAY PARTIALLY PENETRATE THE LOWER LAYERS TO BE REFLECTED BY A HIGHER LAYER !S A CONSEQUENCE  THE RELATIONSHIP BETWEEN THE RANGE TO A TARGET AND THE MEASURED ECHO TIME DELAY BECOMES MULTIVALUED  WITH UNKNOWN PARAMETERS SUCH AS LAYER HEIGHTS THAT MUST BE ESTIMATED BY VARIOUS TECH 
 13, pp. 816–827, 1983. 20. 
 ,p.uf ___---jqlf—- .? 0.001 A 8’= %220:E ~8<220 0U“ 1.. J, Allresistors~watt Interstate coilsclose woundwith#30wire on#’O.D.form iii220 v~ :$k AK5 10( ------ WJ 0.00 220 0.001Ii220 ~%k 6AK5 100 ---JIpf--- ~ 0 z 2200< &0.001 “’”\-controlI13to-lov.. -/220 !220 II+105V %0.001 —)1 —1. 
 It is the basis for several of the chapters  in this Handbook. Some transmitter types, however, are far better than others when the  radar has to employ the doppler-shifted signal to detect moving targets in the midst of  heavy clutter echoes. Examination of the basic radar equation for detection of targets at long range indi - cates that the average power is far more important than the peak power as a measure Chapter 10 ch10.indd   1 12/17/07   2:19:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 2.Change ofPRF from 810 to405 pps. 3.Change ofTR-switch resonant frequency from the magnetron frequency tothebeacon frequency. 4.Change from search tobeacon local oscillator. 
 Radar data were collected only  below 4700 km altitudes, with a resolved footprint on the surface of 23 km along track  and 7 km across track.TABLE 18.6  Planetary Radars Mission URL Planet Year Radar Venera -8;9/10 (USSR) 1 Venus 1972, 75 Radar altimetry Pioneer Venus Orbiter  (PVO) (USA)2 Venus 1978–92 ORAD: Altimeter (also coarse imagery);  17 cm Venera 15/16 (USSR) 3 Venus 1983–84 SAR and altimeter; 8-cm wavelength Magellan (USA) 4 Venus 1990–94 SAR: 12.6 cm (125 m, 75 m pixels), 95%  coverage Clementine (USA) 5 Moon 1994 Bistatic scatterometer experiment; 6 cm Cassini (USA) 6 Titan 2004 TRM: 2 cm, SAR (resolution 0.35–1.7 km)  and altimeter Chandrayaan-1 (India) 7 Moon 2008 Forerunner Mini-RF (USA): 12-cm SAR,  scatterometer Lunar Reconnaissance  Orbiter LRO (USA)8 Moon 2008 Mini-RF: SAR (12 cm and 4 cm), imager  and interferometer 1. http://www.mentallandscape.com/V_RadarMapping.htm 2. http://heasarc.nasa.gov/docs/heasarc/missions/pvo.html#instrumentation 3. 
 7 .30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 using the Kalman gains  Kk+1 = P(k + 1 | k)HT(tk+1)[H(tk+1)P(k + 1 | k)HT(tk+1) + ℜk]−1 (7.33) Because the gains are calculated using the history of all past update times and  accuracies, the gains automatically increase after missed detections and automatically  increase to give greater weight to a detection when it is known to be more accurate,  and they automatically decrease as the track ages, reflecting the value of the detections  already filtered. For example, for a zero random acceleration, Qk = 0, and a constant  detection covariance matrix, ℜk, the a – b filter can be made equivalent to the Kalman  filter by setting  α=− +2 2 1 1( ) ( )k k k (7.34) and  β=+6 1 k k( ) (7.35) on the kth scan. Thus, as time passes, a and b approach zero, applying heavy filtering  to the new samples. 
 Ma, J.; Tao, H.; Huang, P . Subspace-based super-resolution algorithm for ground moving target imaging and motion parameter estimation. IET Radar Sonar Navig. 
 2X. Kerr. D. 
 DC POWER CONDITIONERS ARE USED FOR VOLTAGES APPLIED TO TRANSMITTING DEVICES  THE FREQUENCY AND ITS HARMONICS  OF THE  CONVERTER MUST BE ATTEN 
 Theantenna Figure7.17Principle ortheorgan-pipe scanner.. 248 INTRODUCTION TO RADAR SYSTEMS  cannot be used during this period of ambiguity, called the dead tinte. In one model of the  organ-pipe scanner, 36 elements were fed, three at a time.''* The dead time for this model is  equivalent to rotation past two of the 36 elements; conseqi~ently it was inoperative about 6  percent of the time. 
 interference prior to any nonlinear operation. A digital word in the power-of-2 binary format may be written £ = 2»-(»N+1_M + ^ + ^+...+^) (3,1) where M is the place beyond which all coefficients to the left are zero. Note that M has essentially the same significance as in previous sections. 
 60, pp. 1551-1552, December, 1972.  16. 
 62.Peeler.G.D.M..K.S.Kelleher. andH.P.Coleman: VirtualSourceLuneburg Lenses,Symposium 011 Micr(/\\'Clre Optics,McGillUniversity, Montreal. AFCRC-TR-59-118(1), ASTIADocument 211499. 
             (c)  
 OF 
 30, pp. 723–735, 1992. 34. 
 G. M. Dillard and C. 
 For a circular aperture with uniform distribution, the  field intensity is proportional to  E(4>) = ("do (0 exp (j2rc ~ sin tp cos o)r dr = 1r.r52J 1(~)/~ (7.19}  where c; = 2tr(r0/,l.) sin tp and J 1(~) first-order Bessel function. A plot of the normalized  radiation pattern is shown in Fig. 7.4. 
 I.: Survey of Phased Array Accomplishments and Requirements for Navy Ships.  "Phased Array Antennas." ed. by A. 
 Hadjifotiou, A.: Round-off Error Analysis in Digital MTI Processors for Radar. The Radio and  Electronic Engineer, vol. 47, pp. 
 LAW 
 9.17). This radar isused forairborne detec- tion ofaircraft under blind conditions, and therefore requires asearch over asolid angle intheforward direction. The beamwidth isabout 5°. 
 75. Hansen, V. G.: Constant False Alarm Processing in Search Radars, International CoMerence on  Radar-Present and Future, Oct. 
 One of •the first techniques for achieving frequency-agile magnetrons was known as spin­ tw1i11g. or rotary tu11ing. In this device a rotating slotted disk is suspended above the anode  resonators. 
 A well-known form of the logarithmic detector uses successive detection,6 wherein the detected outputs of Af similar limiter stages are summed as shown by Fig. 3.13. If each stage has a small signal gain G and a limited output level E, the intersections of the approximating segments fall on a curve described by [ 1OgEXM)G^+1 / i I l\]E0(M) = n\E / ^ + E I—J- + - • - + —7 + - (3.6) L log G \GM~l G2 G/J where n is the detector efficiency and E1(M) represents the particular input levels that correspond to the intersections of the line segments, E1(M] = ^- (3.7) GM (b) FIG. 
 SISC.17.7]GENERAL METHODS OFRELAYING SINEANDCOSINE 703 \ b0?Radarvideosignals andtriggerpulse o f2 o ~llj,;,w1 Totransmitter -L= Transformer Audio C+D sine filter/1b iFromC>Ll receiverVideofilter Audio C!+D COS@ 1+3Mc\sec filterjz v wEzil Y1Audio AVC filterf~e I videoandtrigger o !%.o rr 2r7 B Signalata Potential atb FIG. 17.11.—Method ofrelaying sine and cosine by c-w on one r-f carrier. Atleast two methods ofsupplying slowly varying sine and cosine voltages have been successfully applied. 
 H. Pearce, “Calibration of a large receiving array for HF radar,” Proc. Int. 
 BANDWIDTH SIGNAL )N THIS  CASE  THE MOST APPROPRIATE hTHEORY OF THE EXPERIMENTv IS THE TIME 
 The receiver frequency-response function, for purposes of this discussion, is assumed to  apply from the antenna terminals to the output of the IF amplifier. (The second detector and  video portion of the well-designed radar superheterodyne receiver will have negligible efTect on  the output signal-to-noise ratio if the receiver is designed as a matched filter.) Narrowbanding  is most conveniently accomplished in the IF. The bandwidths of the RF and mixer stages of  the normal superheterodyne receiver are usually large compared with the IF bandwidth. 
 Theeffectoferrorsontheradiation patternhaslongbee"recognized bythepractical antenna designer. Theusualrule-of-thumb criterion employed inantenna practice isthatthe. phaseoftheactualwavefront mustnotdifferfromthephaseofthedesiredwavefront bymore than±A/16inordertoensuresatisfactory performance. 
 As such, MOM is not a useful tool for predicting the RCS of, say, a jet fighter in the beam of a radar operating at 10 GHz. The second limitation is that MOM yields numbers, not formulas, and is therefore a numerical experimental tool. Trends may be established only by running a numerical experiment repeat- edly for small parametric changes in the geometry or configuration of an object or in the angle of arrival or the frequency of the incident wave. 
 D.C.. Sept. 22, 1977. 
 40. W. D. 
 CODED WAVEFORMS 'ENERAL /FTEN USED FOR  HIGH 
 J., vol. 34, pp. 5-103, January, 1955. 
 02& WAVEFORMS  AND IT IS GENERALLY DONE WITH A SIMILAR UNFOLDING AND CORRELATION TECHNIQUE  AS DESCRIBED PREVIOUSLY FOR RANGE AMBIGUITIES !S SHOWN IN &IGURE   VELOCITY UNFOLDING OF DETECTIONS INVOLVES ADDING A SET OF SIGNED INTEGERS                 !$   " " # $   !   
 VARYING 
 The factors affecting the design of an HF OTH radar are slightly  different than those affecting conventional microwave radar. This is illustrated by the simple  radar equation commonly used in OTH radar analysis, which is  where R = range  Pa, = average power  G, = transmitting antenna gain  (14.22)530INTRODUCTION TORADAR SYSTEMS sameasthoseofinterest tomicrowave radarandinclude aircraft, missiles, andships.In addition, thelongwavelengths characteristic ofHFradaralsoprovidedistinctive information regarding thesea,aswellasaurora, meteors, andlandfeatures. (Although theHFhandis officially defined asextending from3to30MHz,forradarusagethelowerfrequency limit mightliejustabovethebroadcast band,andtheupperlimitcanextendto40MHzormore.) Theabilitytoseeatargetatlongrangebymeansofionospheric refraction depends onthe natureoftheionosphere (thedensityofelectron concentration) andtheradarfrequency, as wellasthenormalparameters thatenterintotheradarrangeequation. 
 BOARD PHASED ARRAYS  FACTORY CALIBRATION IS USUALLY PERFORMED USING A PLANAR NEAR 
 Thus ifzisthe size oftheclutter atthe. SEC. 16.8] RECEIVER CHARACTERISTICS 647 input ofthereceiver, thetotal increment inamplitude can bewritten as Ax=kx+N, where kzistheamplitude component oftheclutter fluctuation and Nis thecomponent ofthei-fnoise vector inthedirection ofx. 
 Ferrite Phasers and Ferrite MIC' Corn-  ponents," Artech House, Inc., Dedham, Mass., 1974.  (A collection of reprints of papers covering toroidal waveguide phase shifters, dual-mode phase  shifters. Reggia-Spencer phase shifters, other novel ferrite phaser configurations, and ferrite rnicro-  wave integrated components.)  34. 
 E. Nathanson, Radar Design Principles , New York: McGraw-Hill Book Company, 1969,   p. 37. 
 TURE n &OR A CONTINUOUS APERTURE  THE FAR 
 Analogously to the implementation of the cell-averaging CFAR processor, the ampli - tude x(i) can be obtained using a linear, square-law, or logarithmic detector. The loss in detectability due to the clutter map is analogous to the CFAR loss ana - lyzed in the literature for many different conditions. An analysis of the clutter map loss  for single-hit detection using a square-law detector has been presented by Nitzberg.44  These and other results can be summarized into a single universal curve of clutter map  loss, LCM, as a function of the clutter map ratio x/Leff, as shown in Figure 2.90, where   x defines the required false-alarm probability according to Pf = 10−x and Leff is the  effective number of past observations averaged in the clutter map defined as  Leff=−2α α (2.63) For example, for Pf = 10−5 and a  = 0.125, the clutter map loss is LCM = 1.8 dB since   x = 5 and Leff = 15 for this case. 
 ÓÎ°ÎÈ  2!$!2 (!.$"//+   4 0 +OCHANSKI  - * 6ANDERHILL  *6 :OLOTAREVSKY  AND 4 &ARISS  h,OW ILLUMINATION ANGLE  BISTATIC SEA CLUTTER MEASUREMENTS AT 8 
 The screen properties ofimportance inthis connection arethe type ofdecay and themanner inwhich thelight intensity “builds up” under successive excitations. Toexamine their effects, consider first ascan which issoslow that either the limitations ofachievable persistence or therequirements offreedom from display confusion due totarget motion prevent appreciable storage ofinformation from one scan tothe next. Insuch acase, the averaging must bedone over asingle pulse group. 
 Lin, H. Fang, E. Im, and U. 
 This permits switching times of the order of microsecollds. Wticreas  hysteresis was a nuisance to be tolerated in the Reggia-Spencer device, the latching phase  shifter takes advantage of the hysteresis loop to produce the two discrete values of phase shift  without the need for continuoi~s drive power.  The toroid phase shifter is tiotirc~ciproc.rr1 in that the phase shift depends on the direction of  propagation. 
 PENSATE FOR LINEAR GAIN AND PHASE DEVIATIONS HOWEVER  AS FOR THE CASE OF THE ,.! NONLINEARITIES DESCRIBED ABOVE  COMPENSATION FOR NONLINEAR CHARACTERISTICS IS EITHER IMPRACTICAL OR IMPOSSIBLE WHEN THE CAUSE OF THE NONLINEAR DISTORTION IS OUTSIDE THE DIGITIZED BANDWIDTH %VALUATION ! THOROUGH EVALUATION OF ALL ELEMENTS OF THE RECEIVER IS NEC 
 I. Skolnik (ed.),  McGraw-Hill Book Co., N.Y., 1970.  64. 
 ANTENNA SYSTEMS BECAUSE OF INTERNAL REFLECTIONS AND LEAKAGE THROUGH THE CIRCULATOR &IGURE  SHOWS THE KIND OF SYSTEM THAT MAY BE USED TO MEASURE SCATTERING FROM  WITHIN A VOLUME "Y DETERMINING THE SPECTRUM OF THE RETURN  THE USER CAN ESTABLISH THE SCATTERING FROM DIFFERENT RANGES 4HIS SYSTEM HAS BEEN USED IN DETERMINING THE SOURCES OF SCATTER IN VEGETATION n AND SNOW 5LTRASONIC WAVES IN WATER CAN BE USED TO SIMULATE ELECTROMAGNETIC WAVES IN AIRn  "ECAUSE OF THE DIFFERENCE IN VELOCITY OF PROPAGATION  AN ACOUSTIC FREQUENCY OF  -(Z  CORRESPONDS WITH A WAVELENGTH OF  MM 3UCH A WAVELENGTH IS OF A CONVENIENT SIZE FOR MANY MODELING MEASUREMENTS  AND  OF COURSE  EQUIPMENT IN THE  
 BASED 3!2 SYS 
 23.23  Multiple Radar s  .................................................  23.24  Rapid Scanning   .................................................  23.25  Airborne and Space-Borne Radars  .................... 
 DAMENTAL TO THE CONSTRUCTION AND CIVIL ENGINEERING INDUSTRIES  THE POLICE AND FORENSIC SECTORS  SECURITYINTELLIGENCE FORCES  AND ARCHAEOLOGICAL SURVEYS '02 HAS BEEN VERY SUCCESSFULLY USED IN FORENSIC INVESTIGATIONS  4HE MOST NOTORI 
 vanKasteren, Ground-based X-band Radar Backscatter  Measurements of Wheat, Barley and Oats , Wageningen NETHERLANDS: Center for  Agrobiological Research, 1989. 130. B. 
 2.1. We shall try, where possible, tomodify the radar equation tosuit the new circumstances, but itwill beour broader purpose todescribe, ifonly qualitatively, certain propagation phenomena peculiar tothemicrowave region, This isavast subject. Itincludes some exceedingly difficult problems inmathematical physics, notyetcompletely solved; itincludes topics inmeteorology; above all,since itinvolves the weather and the variegated features oflandscape and seascape never susceptible ofexact mathematical description, itincludes alarge collection ofobservations and experience, rarely easy tointerpret. 
 Barton, Norwood, MA: Artech House, 1987. 17. R. 
 73, pp. 312-324, February 1985. 10. 
  
 The logical extension from acoustic to electromagnetic methodology  is a small step in comparison. ch18.indd   59 12/19/07   5:15:20 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 BASED RADARS  FOR EXAMPLE  7 COMPARED TO  K7  THE SPECTRUM INTERFERENCE LEVELS ARE MUCH REDUCED AND  THEREFORE  EXTENDED USE OF THIS TECHNOLOGY COULD RESULT IN BETTER USE OF THE 2& SPECTRUM !LSO  THE HIGHLY CONTROLLED WAVEFORMS ARE EXPECTED TO CREATE LESS SPECTRAL NOISE THAN TYPICAL MAGNETRON 
 SIDEBAND PHASE 
 Matlt. Comp .. vol. 
 BATIONS IN THE OCEANS MEAN SURFACE DUE TO SPATIAL VARIATIONS IN THE %ARTHS GRAVITY 4HE ORBIT SHOULD NOT REPEAT FOR  ^ YEARS TO YIELD AN AVERAGE GROUND TRACK SPAC 
 24.2 TERMINOLOGY EW is defined as a military action involving the use of EM energy to determine,  exploit, reduce, or prevent radar use of the EM spectrum.8–11 The operational employ - ment of EW relies upon the capture of radar EM emissions using electronic intelli - gence (ELINT) devices, collating the information in support databases that are then  used to interpret EM emission data, to understand the radar system functions, and  to program reactions against the radar. EW is organized into two major categories:  electronic warfare support measures (ESM) and ECM. Basically, the EW community  takes as its job the degradation of radar capability. 
 - - - - - . - - - - - - .  (4n)'R '  Thus the echo from surface clutter varies inversely as the cube of the rang$ ratllcr than  inversely as the fourth power as is the case for point targets. 
 Thedynamic rangeofaradardisplay,whether PPI orA-scope, isfarlessthantherangeofecho-signal amplitudes thatcanbeexpected from clutter.Itisnecessary, therefore, tokeepthelargeclutterechoesfromsaturating thedisplay andpreventing thedetection ofwantedtargets.Echoesfromthevarioussourcesofclutter experienced byacivil-marine radarmightbe80dBgreaterthanreceivernoise.yetthereceiver mightonlybeabletodisplaywithoutsaturation signalsthatarelessthanabout20to25dB abovenoise.22Sensitivity timecontrol(STC),orsweptgain,iswidelyusedtoreducethe largeechoesfromclose-inclutter.STCisatimevariation ofthereceiver gain.Atth~endof thetransmission oftheradarpulsethereceiver gainismadelowsothatlargesignalsfrom nearbyclutterareattenuated. Echoesfromnearbytargetswillalsobeattenuated; butbecause oftheinversefourth-power variation ofsignalpowerwithrange,theywillusuallybelarge enoughtoexceedthethreshold andbedetected. Thereceivergainincreases withtimeuntil maximum sensitivity isobtained atrangesbeyondwhichclutterechoesareexpected. 
 296-297  Fraunhofer region, antenna, 229 Frequency agility:  ECCM, 548  for glint reduction, 170- 172  and sea echo, 485  Frequency diversity, 548  Frequency measurement accuracy, 407-408  Frequency modulated CW radar, 81-92  Frequency-scan arrays, 298-305  Frequency-scan radar. and pulse compression.  433  Fresnel region, antenna, 229  Fresnel zone plate, 523, 527  Gain. 
 Patent  no. 3,916,416. Oct. 
 J. Spafford, “Optimum radar signal processing in clutter,” IEEE Trans. Information Theory ,  vol. 
 A more threatening ECM against tracking radars is DECM. These threats require  considerably less energy than noise jamming (a feature particularly important on tacti - cal aircraft, where available space is limited). Nevertheless, they are very effective in  capturing and deceiving the range gate (with the RGPO technique), the velocity gate  (with the VGPO technique), and the angle-tracking circuits. 
 2.27b). The pencil beam is axially symmetric, or nearly so. Beamwidths of  typical pencil-beam antennas may be of the order of a few degrees or less. 
 PROPAGATION OF RADAR WAVES 453  Elcrntcd ducts. i\n example of propagation in elevated ducts is found in the "tradewin<l  region" between the midoccan. high-pressure cells and the equatorial doldrums. 
                        # &'  "             . ££°Îä  2!$!2 (!.$"//+  DESIGNER IN ORDER TO SATISFY THE 2& ELECTRICAL  DC ELECTRICAL  THERMAL  AND RELIABILITY  REQUIREMENTS 0ACKAGING OF --)# COMPONENTS INTO THE 42 MODULE MUST TAKE INTO CONSIDERATION    MULTIPLE ELEMENTS AS THEY IMPACT THE ELECTRICAL PERFORMANCE 0OWER #ONDITIONING #ONSIDERATIONS  0ULSED TRANSMIT AMPLIFIERS CAN CONSUME  VERY HIGH DC CURRENTS AND SPECIAL DESIGN ATTENTION MUST BE PAID TO PARASITIC INDUC 
 MENTS REPORTED BY DIFFERENT INVESTIGATORS FOR EXACTLY THE SAME SET OF PARAMETERS 4HIS IS SEEN CLEARLY IN &IGURE  A AND B  WHICH COMPARES THE GRAZING 
 Trunk The Johns Hopkins University Applied Physics Laboratory 7.1 INTRODUCTION As digital processing has increased in speed and digital hardware has decreased in cost  and size, radars have become more and more automated, so that automatic detection  and tracking (ADT) systems are associated with almost all but the simplest of radars. In this chapter, automatic detection, automatic tracking, and sensor integration  techniques for surveillance radars are discussed. Included in the discussion are vari - ous noncoherent integrators that provide target enhancement, thresholding techniques  for false alarms and target suppression, and algorithms for estimating target position  and resolving targets. 
 The problem isespecially acute onthe slower scans, partly because ofthe long time “between excitations and partly because the cascade screens areless efficient than those with less persistence. Inintensity-modulated displays thecharacteristics ofthescreen have important effects onthe signal-to-noise discernibility y. As has been pointed outinChap. 
 The ground reflectivity has been assumed equal to the target reflectivity  (this is quite a pessimistic assumption, because in many cases of practical interest,  the target reflectivity is higher). A receiver thermal noise, 40 dB below the target  return, has also been summed to the received signal. The ground echo is first can - celed, by using a two-element antenna and two time samples. 
 By using the proposed method, we not only increase the number of images, but we can also retain the important information of the images. Some noise is still in the background, but concerning SAR images, that noise of the sea surface can be accepted. Because of the characteristics of SAR images, the angle of pictures may cause a lot of difference in CNN training than simple transposition. 
 MONOPULSE RECEIVERS  ARE DESCRIBED IN 3ECTION  OF THE SECOND EDITION  OF THIS HANDBOOK -ODERN RADAR SYSTEMS ARE MOSTLY DESIGNED TO  MAXI 
 Provide IF Limiters prior to A/D converters. MTI radars require that IF  bandpass limiters exist prior to an A/D (analog/digital converter). The limiter prevents  any clutter return from exceeding the dynamic range of the A/D. 
 AMPLITUDE NOISE SOURCES CAN BE  RESOLVED IF THEY ARE SEPARATED IN ANGLE BY   K,  IN RADIANS  WHERE  K IS THE WAVELENGTH  AND , IS THE APERTURE LENGTH 7HEN THE INCIDENT WAVE IS RECEIVED WITH A HIGH *.2  AN  ADAPTIVE ARRAY ANTENNA MAYIN PRINCIPLEACHIEVE A NARROWER  ADAPTIVE BEAMWIDTH   GIVING A SHARPER BEARING ESTIMATION OF THE INCIDENT WAVE )F ACCURATE STROBES OF THE JAM 
 2. Human behavior is certainly less predictable than  that of an electronic device. However, it appears that an operator's performance can be as  good as that predicted for the ideal electronic threshold detector if the operator is well trained,  motivated, alert, not fatigued, and the display is properly designed. 
 HORIZON RADAR v #HAPTER  IN  2ADAR (ANDBOOK  - ) 3KOLNIK  ED   ND %D  .EW 9ORK -C'RAW 
 Another example is shown in Fig. 12.9. This is the small illuminated area for a narrow-beam, short-pulse system. 
 60·61 The linearly polarized beam radiated by a ftat, two-dimensional array of spirals  may be scanned by rotating the individual spiral antenna elements. One degree of mechanical  rotation corresponds to a phase change of one electrical degree. No additional phase-shifting  devices are required. 
 Table 7.6gives the de ﬁnition for the Douglas sea states, usually used in radar. Much more discussion can be found in [ 6]. The minimum detectable signal is determined by the received signal, clutter and noise levels associated with a given target position in the radar beam, combined with Figure 7.4. 
 AXIS CHARACTERISTICS OF THE PARABOLOIDAL REFLECTOR v .AVAL  2ES ,AB 2EPT     ! 7 2UDGE AND . ! !DATIA  h/FFSET PARABOLIC REFLECTOR ANTENNAS ! REVIEW v  0ROCEEDINGS  )%%%  VOL   NO   PP n  $ECEMBER   $ ' +IELSY  h0ARABOLIC CYLINDER AERIALS v 7IRELESS %NG  VOL   PP n  -ARCH   2 , &ANTE ET AL  h! PARABOLIC CYLINDER ANTENNA WITH VERY  LOW SIDELOBES v  )%%% 4RANS  VOL !0 
 Equation (2.27) is sometimes called the Rice probability-density  function.  The probability that the signal will be detected (which is the probability of detection) is the  same as the probability that the enve]ope R will exceed the predetermined thresho]d VT. The . 
 SIGNAL  % FIELD IS ACCOMPLISHED INDEPENDENTLY OF THE  DIFFERENCE 
 One portion ofthetimer generates a square wave (Waveform b,Fig. 12”1)which performs this function and usually finds other applications within thetimer. Ifthedisplay includes arange sweep, asisnearly always thecase, the timer generates the waveform that ultimately produces it. 
 fault location, data recording arid simulations; and the e.uecitrille nraiiagement of the radar  by assigning priorities to the various tasks and how tliey should be performed so as to achieve  a corilprotnise betweer1 tlie required radar actions and the resources available in the radar  and cornputer. 111 addition, tlie computer provides the means whereby an operator can niani~ally  intcr act with tlie radar  Beam-steering computer. Although a single general-purpose cornputer can be used to perform  all ttie computatiotis and control required for a phased-array radar, it is often desirable to  utilize a separate, special-purpose computer for beam steering. 
 /\teach range interval the detector integrates n pulses, where n is the number . 184 INTRODUCTION TO RADAR SYSTEMS  of pulses expected to be returned from a target as the antenna scans past. The integrated pulses  are compared with a threshold to indicate the presence or absence of a target. 
 TUDE XI  CAN BE OBTAINED USING A LINEAR  SQUARE 
 The course on which this book is based is a proven method for introducing  the student to the subject of electronic systems. It integrates and applies the basic concepts  found in the student's other courses and permits the inclusion of material important to  the practice of electrical engineering not usually found in the traditional curriculum.  Instructors of engineering courses like to use texts that contain a variety of problems that  can be assigned to students. 
 Lab. Rept. 7349,  December 1971. 
 2. Probabilistic Data Association (PDA)  Another alternative is the probabilistic  data association (PDA) algorithm62,63,64 where no attempt is made to assign tracks  to detections, but instead, tracks are updated with all the nearby detections— weighted by the perceived probability of the track being the correct association.  Because PDA relies on erroneous associations essentially “averaging out,” it is  most effective when tracks are far enough apart that nearby detections originate  from spatially random noise or clutter exclusively and when the tracking gains  are small (i.e., when the tracking index gtrack is small). 
 .............  7  SIGNAL MONITORING  ................................ ................................ 
 Navy Department  —The Breit and Tuve experiment—The  Appleton experiments in 1920—~The Watson~  Watt request in 1935, and how the world’s  first radar aircraft test was made at Daventry  in February 1935.  SHORT, SHARP SHOUTS  The essence of the pulse system—Funda-  mentals of radar, and the relationship be-  tween range-finding and the speed of electro-  magnetic waves—Radio-wave speed and ob-  ject distance—How radar is used as an  electrical stop-watch—The use of a cathode-  ray-tube display as an electron timing device.  THe EcHO COMES HOME  The miracle we now take for granted—How  tiny packets of radioenergy are received Why  the radar receiver and transmitter must work  in step—Necessity for high-gain receivers to  produce a readable display—Relationship be-  tween the noise-level and the signal voltage—  The ‘Z’ factor—Wavelengths used for popy~  lar radar equipments—Function of the modu-  lator—How the pulse-recurrence frequency  is chosen—Radar aerial arrays, and why the  radiation is beamed—Common T-and-R  arrays. 
 Fishbein, S. W. Graveline, and O. 
 534 THERECEIVING SYSTEM—INDIC’ATORS [SEC. 13.16 slowly varying voltages isappreciably easier than would bethe case with the sawtooth waveforms involved inthe resolved-time- base method. Methods 2and3 can reapplied either tomagnetic ortoelectrostatic cathode-ray tubes, but, because oftheir inferiority forintensity -modu- lated displays, thelatter tubes areseldom used. 
 *,  Ê 
 L/1/RAS (T 1352), 1943 (TNA AVIA 26/354) [3] Technical Development of Lucero Mks. I and II, TRE Report No. 33 R/121/JMMP (T 1359), Feb 1943 (TNA AVIA 26/361) [4] H 2S Mark II Equipment and A.S.V. 
 Figure 20: Signal -Noise -Ratio 3dB shown  on an A -Scope  . Radartutorial (www.radartutorial.eu)   16 Radar Range Equation (Example given)   One of the important uses of the radar range equation is in the determination of detection ra nge, or  the maximum range at which a target has a high probability of being detected by the radar.   Table 3: Example of a real radar set     If we substitute the metric values from the upper ta ble into the radar range equation we get:    6 2 2 3 1522 4 4max 31 10 1900 0.11 14 4 5 10 128.8Wm W76.5 km 4tx t MDS sPGR PL                The result expressed in nautical miles is 41.3 NM. 
 With signal processing technology, the target image can be obtained by separating position (x,y)and amplitude gi(x,y)from complex signal sir(t). Figure 1. Geometric sketch of dual-antenna InISAR imaging. 
 The optimal linear estimate is deter - mined by requiring the adapted estimation error be orthogonal to the observed vec - tor, r. Steady-state conditions are assumed in this derivation, thus the condition for  orthogonality is  E{r e∗} = 0 (3.24) where E{} is the expectation, e is the estimation error, and * is the complex conjugate.  The adaptively weighted estimate is obtained by weighting the received signal vector  by the estimate of the adaptive weights:  ˆ ˆ ' s w r = (3.25) With d defined as the desired signal (a main-beam target), the estimation error is  obtained from the following equation. 
 However, a frequency spec- trum measured at a point can contain no knowledge of wave direction; so a wavenumber spectrum W(K) is often defined in terms of the frequency spectrum S(f) by the relation W(K) = S(f(K))(df/dK) (13.2) with the relation between/and K given by Eq. (13.1). To account for the wind direction, W(K) is sometimes multiplied by an empirical function of K and direc- tion v relative to the (up)wind direction. 
 INCH SHELLS AND   
 The attenuation is commanded based on measurements of the noise  during periodic calibration. Digital Preprocessing.  The advent of high-speed, high-dynamic range analog- to-digital converters (A/Ds) allows IF-sampling and digital basebanding. 
  TEST   AND ADAPTIVE 02& SELECTION &)'52%  4YPICAL -02& PROCESSING ADAPTED COURTESY 3CI4ECH 0UBLISHING  . 
 14, Chap. 2, along with further discussion of visual detection. Other Detection Methods. 
 ERALLY THIS SHOULD BE  OF THE SAMPLING INCREMENT HOWEVER  PRACTICALLY A STABILITY IN THE ORDER OF  PS TO   PS IS ACHIEVED 4HE EFFECT OF TIMING INSTABILITY IS TO CAUSE A  DISTORTION  WHICH IS RELATED TO THE RATE OF CHANGE OF THE 2& WAVEFORM %VIDENTLY  WHERE THE 2& WAVEFORM IS CHANGING RAPIDLY  JITTER IN THE SAMPLING CIRCUITS RESULTS IN A VERY NOISY RECONSTRUCTED WAVEFORM 7HERE THE RATE OF CHANGE OF SIGNAL IS SLOW  JITTER IS LESS NOTICEABLE .ORMALLY  CONTROL OF THE SAMPLING CONVERTER IS DERIVED FROM A SAMPLE OF THE OUTPUT FROM THE PULSE GENERATOR TO ENSURE THAT VARIATIONS IN THE TIMING OF THE LATTER ARE COMPENSATED AUTOMATICALLY 4HE KEY ELEMENTS OF THIS TYPE OF RADAR SYSTEM ARE THE IMPULSE GENERATOR  THE TIMING CONTROL CIRCUITS  THE SAMPLING DETECTOR  AND THE PEAK HOLD AND ANALOGUE TO DIGITAL CONVERTER &REQUENCY $OMAIN 2ADAR  4HE MAIN POTENTIAL ADVANTAGES OF THE FREQUENCY  DOMAIN RADAR ARE THE WIDER DYNAMIC RANGE  LOWER NOISE FIGURE  AND HIGHER MEAN POWERS THAT CAN BE RADIATED 4HERE ARE TWO MAIN TYPES OF FREQUENCY DOMAIN RADAR  &REQUENCY -ODULATED #ARRIER 7AVE &-#7  AND 3TEPPED &REQUENCY #ARRIER 7AVE 3&#7  &-#7 RADAR TRANSMITS A CONTINUOUSLY CHANGING FREQUENCY OVER A CHOSEN FREQUENCY RANGE ON A REPETITIVE BASIS 4HE RECEIVED SIGNAL IS MIXED WITH  A SAMPLE OF THE TRANSMIT 
 The only degree of freedom remaining in the data-rate budget was the number of  bits retained for each sample in the raw SAR datastream. Working back through the  DSN constraint, it turned out that there were only two bits available for Magellan ’s  raw SAR data. Yes—a 2-bit SAR! And again, the unique characteristics of an orbital SAR made  this an acceptable solution for the Magellan  design. 
 Continuous  waveforms (CW) also can be used by taking advantage of the doppler frequency shift to  separate the received echo from the transmitted signal and the echoes from stationary clutter.  Unmodulated CW waveforms do not measure range, but a range measurement can be made  by applying either frequency- or phase-modulation.  1.2 THE SIMPLE FORM OF THE RADAR EQUATION  The radar equation relates the range of a radar to the characteristics of the transmitter,  receiver, antenna, target, and environment. 
   PP n  *ULY   ' 6 4RUNK AND * $ 7ILSON  h!UTOMATIC DETECTOR FOR SUPPRESSION OF SIDELOBE INTERFERENCE v IN  )%%% #ONF $ECISION  #ONTROL  $ECEMBER n    PP n  ' 6 4RUNK AND 0 + (UGHES ))  h!UTOMATIC DETECTORS FOR FREQUENCY 
 3. If the best possible stability is required. Magnetrons are not stable enough to be suitable for very long pulses (e.g., 100 JJLS), and starting jitter limits their use at very short pulses (e.g., 0.1 JJLS), especially at high power and lower frequency bands. 
 Although they may each be small, the sum total can result in a significant reduction in radar  performance. It is importat~t to understand the origins of these losses, not only for better  predictions of radar range, but also for the purpose of keeping them to a minimum by careful  radar design.  THERADAR EQUATION 61 wherePdisthesingle-scan probability ofdetection. 
 Du, X.; Duan, C.; Hu, W. Sparse representation based autofocusing technique for ISAR images. IEEE Geosci. 
 22. Clancy, R. M., J. 
 MENT TRANSMITTERS &OR NEW RADAR SYSTEMS  SYSTEM DESIGNERS HAVE BEEN MOTIVATED BY THESE CONSIDERATIONS TO CHOOSE AS HIGH A DUTY CYCLE AS POSSIBLE  BOTH TO REDUCE THE PEAK POWER REQUIRED AND TO PERMIT USING SOLID 
 Open-ocean measurements of capillary waves are especially difficult to perform.15 For a gravity wave, the frequency/and the wavenumber K are related by the dispersion relation f=(V2^(gK)l/2 (13.1) where g is the acceleration of gravity and K = 2WA, with A being the wavelength. Although each individual gravity wave obeys this relation, the waves at a point on the sea surface could come from any direction; so they are characterized by a two- dimensional propagation vector with orthogonal components Kx and Ky9 where the K to be used in Eq. (13.1) is the magnitude K = (Kx2 + K2)112. 
 POLARIZATION 2#3 OF A ROD AND A HEMISPHERE MOUNTED  ON A PERFECTLY CONDUCTING SURFACE 7ITH THESE CANONICAL SHAPES  AN ESTIMATE OF 2#3 CAN BE MADE FOR SURFACE CRAFT BY MATCHING  , AND 2 TO THE PRINCIPLE DIMENSIONS TO THE  TARGET &OR SMALL VESSELS  THE MAST HEIGHT WILL BE OF MOST IMPORTANCE  &OR SURFACE  TARGETS  WHERE THE MAXIMUM 2#3 OCCURS WITH VERTICAL POLARIZATION  A  D" SKYWAVE 2#3 ENHANCEMENT RESULTS FROM THE IMAGE FIELD 4O ILLUSTRATE THE 2#3 BEHAVIOR OF A TYPICAL AIRCRAFT IN MORE DETAIL  &IGURE   SHOWS THE 2#3 OF THE & 
 940). The radome illustrated, housing theantenna shown inFig. 9.12, isalmost 9ftwide, 3;ftdeep, and 13ftlong. 
 Although thenumber ofsets of video signals islarge, theuseofdirectional antennas eases ther-fproblem, and the continuous scan renders scanner synchronization relatively simple. Inthesecond example, one setofradar signals and one setofbeacon signals are relayed toground from along-range airborne radar set arranged topermit sector scanning. Incontrast totheformer case, the “picture” data are relatively simple, but the requirement oflarge angular coverage forces the use oflow-gain antennas and puts asevere requirement onthe r-fsystem. 
 AES-7, pp. 160-170, January, 1971.  53. 
 While these solutions constitute interesting academic exercises and can, with some study, reveal the nature of the scattering mechanisms that come into play, there are no known tactical targets that fit the solutions. Thus, exact solutions of . the wave equation are, at best, guidelines for gauging other (approximate) meth- ods of computing scattered fields. 
 13.7. The Generation ofRectangular Waveforms.-A rectangular waveform isone whose outstanding characteristics aresteep, alternately positive and negative wavefronts with aspace between (for example, Fig. 13.12). 
 Figure 8showed the resulting images, which were normalized to the same total energy. Figure 8a, b were formed using the classical 2D focusing algorithm with a rectangular window and a Taylor window in azimuth, respectively. High azimuth sidelobes can be seen in Figure 8a, which can be suppressed with a Taylor window at the expense of resolution (Figure 8b). 
   P   -ARCH   3 2AMO AND * 2 7HINNERY   &IELDS AND 7AVES IN -ODERN 2ADIO   ND %D  .EW 9ORK *OHN 7ILEY   3ONS    PP n  * ! 3TRATTON  2EF   PP n 2 & (ARRINGTON   &IELD #OMPUTATION BY -OMENT -ETHODS  .EW 9ORK -ACMILLAN #OMPANY     2 % +LEINMAN  h4HE 2AYLEIGH 2EGION v 0ROC )%%%  VOL   PP n  !UGUST  * 7 #RISPIN  *R AND + - 3IEGEL  EDS   -ETHODS OF 2ADAR #ROSS 3ECTION !NALYSIS  .EW 9ORK  !CADEMIC 0RESS    PP n  % & +NOTT  h! PROGRESSION OF HIGH 
 Saxton J. A.. J. 
   NO   -ARCH   PP n  ' -ORRIS  !IRBORNE 0ULSE $OPPLER 2ADAR  .ORWOOD  -! !RTECH (OUSE    2 3CHLOLTER  h$IGITAL REALTIME 3!2 PROCESSOR FOR #  8 BAND APPLICATIONS v IN  )'!233    :URICH  VOL   P   2 +LEMM  h!IRBORNE -4) VIA DIGITAL FILTERING v IN  )%% 0ROCEEDINGS  VOL   PART &  NO      P   4ECHNOLOGY 3ERVICE #ORP  h!DAPTAR SPACE 
 DELAY SECTIONS  WHICH CAN BE IMPLE 
 ENCE POTENTIAL WITH OTHER IN 
 193-198  Coaxitron, 213  Coded pulse, 428-43 l  Coherent detector. 385-386  Coherent reference, in MTI. 102  Coho, 105, 141  Cold-cathode emission. 
 Itisbeyond the scope ofthis chapter togofurther into the problems ofIFF. Apeace-time requirement that islikely topose prob- lems ofsimilar character, although oflesser complexity, isthat ofcontrol ofairtraffic inthe neighborhood ofairports where thetraffic islikely to beheavy. 8.4. 
 20, pp. 1433– 1448, 2003. 101. 
 vol.3.pp.IR,20,January, 1960. 17.Rhodes, D.R.:"Introduction toMonopulse," McGraw-Hili BookCompany, NewYork,1959. tR.Barton,D.K.:"Radars. 
 Not only is amplification at IF less costly and more stable than at microwave frequency, but the wider percentage bandwidth occupied by the desired echo simplifies the filtering operation. In addition, the superhetero- dyne receiver can vary the LO frequency to follow any desired tuning variation of the transmitter without disturbing the filtering at IF. These advantages have been sufficiently powerful that competitive forms of receivers have virtually dis- appeared; only the superheterodyne receiver will be discussed in any detail. 
 Î°n  2!$!2 (!.$"//+  WAS  OF THE 02& )F THE RADAR FREQUENCY WERE  '(Z  02&  K(Z  AND GROUND SPEED   KT  THE NOTCH WOULD HAVE TO BE HELD WITHIN  KT OR 6G "ECAUSE OF THESE REQUIREMENTS AND THE WIDTH OF THE PLATFORM 
 10.7. The radar  video is passed through a threshold detector, which may be thought of as a bottom clipper.  Only those signals whose amplitude exceeds the preset threshdd are allowed to pass. 
 (2.39a),  hut the fluctuations arc more rapid than in case J and arc taken to be independent from  pulse to pulse instead of from scan to scan.  Case 3. In this case. 
 the receiver sensitivity is not determined by thermal noise as at microwaves, but by  quantum effects. The noise power per unit bandwidth at most laser frequencies is given by  No= hf (14.3R)  where h = Planck's constant = 6.626 x 10--'4 J · s, andf = rrequcncy. The ramiliar expression  for thermal noise power at microwave frequencies (N0 = kT, where k = Boltzmann's constant  and T = absolute temperature) does not apply when kT ~ hf lt is the coarseness of the laser  signal itself. 
 MENT (OWEVER  EMISSIVITY IS A FUNCTION OF THE ROUGHNESS OF THE SURFACE   AS WELL AS  ITS TEMPERATURE AND DIELECTRIC CONSTANT  WHICH IS THE VARIABLE OF INTEREST 4HE !QUARIUS PAYLOAD INCLUDES AN , BAND  -(Z  SCATTEROMETER TO MEASURE SURFACE ROUGHNESS 4HE SCATTEROMETER AND RADIOMETER SHARE THE SAME  
 BASED RADAR  AND   GROUND 
 The interference due to power being reflected back to the transmitter, causing a change in  tile impedance seen by the transmitter. This is usually important only at low altitudes. It  can be reduced by ati attenuator introduced in the transmission line at low altitude or by a  directional coupler or an isolator. 
 The superheterodyne receiver utilizes one  or more local oscillators and mixers to convert the signal to an intermediate fre - quency that is convenient for filtering and processing operations. The receiver can  be tuned by changing the first LO frequency without disturbing the IF section of the  receiver. Subsequent shifts in intermediate frequency are often accomplished within  the receiver by additional LOs, generally of fixed frequency. 
 However, it is not the isolation between transmitter and receiver ports  that usually determines the amount of transmitter power at the receiver, but the impedance  mismatch at the antenna which reflects transmitter power back into the receiver. The VSWR is  a measure of the amount of power reflected by the antenna. For example, a VSWR of 1.5  means that about 4 percent of the transmitter power will be reflected by the antenna mismatch  in the direction of the receiver, which corresponds to an isolation of only 14 dB. 
 It can eﬀectively avoid the decrease of ArcSAR imaging quality. This paper proceeds as follows. The ArcSAR geometric model and signal model that consider the terrain of the scenes is introduced in Section 2. 
 Syst. 2003 ,39, 351–357. [ CrossRef ] 12. 
 Peebles, P. Z .. Jr.: Radar Rain Clutter Cancdlation Bounds Using Circular Polari.rntion. 
 AMBIGUOUS WAVEFORM 4HIS REQUIRES MULTIPLE DETECTIONS FROM THE  SAME TARGET !SSUME A DOPPLER FILTER BANK OF N 
 One ofthe shortcomings ofmicrowave magnetrons istheir limited adaptability todifferent requirements. This circumstance has forced the design and production ofanextremely large number oftube types. Although the development ofmicrowave magnetrons inthis country began only inlate 1940, there now exist over 100 distinct types ofmag- netrons, despite early and continuing attempts atstandardization. 
 & FIG.103?, -Group oftypical high-vacuum switch tubes.0 &. SEC 10.9] THE HARD-lUBE PULSER 371 toonly 1/10,000 ofthe peak current, or2ma, the power loss at35kv anode voltage is70~vatts. Toreduce leakage current, thegrid structure ofaswitch tube must surround the emitting area ofthe cathode com- pletely, and must give auniform field over the entire cathode. 
 Maps show subsidence rate in Region 2 ( a), and time-series subsidence at the four points H-K ( b). 224. Sensors 2019 ,19, 743 Points H, I and J are close to new buildings, new roads and a high-rise building, respectively (Figure 12). 
 Aswas previously mentioned, thebeam current inamagnetic tube isproportional tothecube ofthegrid-voltage swing measured from cutoff, which isthe operating point inthe absence ofsignal. This means that asignal of,forexample, half the voltage ofalimited signal will, inprinciple, give only one-eighth asmuch light intensity. Inactual fact the difference isnot sogreat asthis, because ofthetendency ofthe screen tosaturate onstrong signals. 
 Millman. y. H.: Atmospheric Effects on VHF and UHF Propagation, Proc. 
 W. Lynch: Principles and Techniques of Satellite Navigation  Using the Timation I1 Satellite, Naval Research Laboratory Rep. 7252, June 17, 1971, Washington. 
 Pliasc II.  Nc~t.ril Rt~setirc.11 L[~horutory Rcport 6749, Washington, D.C., Oct. 21, 1968. 
 Spread spectrum communication systems68 employ waveforms similar to  those of pulse compression radar. The purpose of such waveforms in communications is to  allow multiple simultaneous use of the same frequency spectrum. This is achieved by coding  each signal differently from the others. 
 Figure 1.2  Section of the Marconi Speech in 1922 before the IRE   In Germany it was the GEMA (Gesellschaft für Elektrische und Mechanische Apparate), Pinsch,  and Telefunken, which became known for their work on Radar systems.  The first instruments were very simple and operated with relatively low frequencies.  The following lists a few impo r- tant dates:   1930 US NRL (L.A. 
 1970.  16. fiidayct. 
 50. Kock, W. E.: Metal Lens Antennas, Proc. 
 1) TRANSMITTEDPULSES (PRF NO. 2) RECEIVEDPULSES (PRF NO. 2) COINCIDENCE OFTRANSMITTEDPULSES COINCIDENCE OFRECEIVEDPULSES . 
        !   !              . Óx°ÓÈ  2!$!2 (!.$"//+  $IGITAL &ILTERS AND !PPLICATIONS  4HIS SECTION  DESCRIBES SEVERAL OF THE MAJOR FORMS OF DIGITAL FILTERS  AND HOW THEY ARE USED IN RADAR SIGNAL PROCESSING &INITE  )MPULSE  2ESPONSE  &)2   AND  )NFINITE  )MPULSE  2ESPONSE  ))2   &ILTERS  &IGURE    SHOWS A BLOCK DIAGRAM OF A DIRECT 
 ThesUbreflector wassupported byatransparent (dielectric) cone,with resistive-card absorbers embedded inthe'support coneandoriented soastoreducethe I . cross-polarized wide-angle radiation bymore t~an20dB. • . 
 Geosci. Electron ., GE-17, IEEE, October 1979. 28. 
 Note that there are several false positives around the ridges of the building. In the second image, change colors (red and cyan) were made more pronounced to highlight the false positives. 269. 
 !"   
 The control block on the bottom of the figure determines whether additions or  subtractions are performed at each stage, based on the algorithm described previously.  If the ADD/SUB block in the Q channel performs an addition, the same block in  the I channel will perform a subtraction, and vice-versa. The result of the ADD/SUB  blocks is stored in a register (REG) on the next clock edge and passed to the next stage  of processing. 
 V. Holdam, Jr., and D. Macrae, Jr. 
 TIES  BUT THIS IS COMPENSATED BY ACCESS TO HIGHER OPERATING FREQUENCIES !N INCREASE IN THE NUMBER AND SEVERITY OF MAGNETIC STORMS AND SUDDEN IONOSPHERIC DISTURBANCES IS ANOTHER CONSEQUENCE OF HIGHER SOLAR ACTIVITY  AS ARE INCREASED  POST 
 TARGET SIGNALS SUPERIMPOSED ON CLUTTER SIGNALS ! RADAR WITH  D" 3#6 CAN  DETECT AN AIRCRAFT FLYING OVER CLUTTER WHOSE SIGNAL RETURN IS   TIMES STRONGER .OTE THAT  IT IS IMPLICITLY ASSUMED IN THE ABOVE DEFINITION THAT SIGNAL AND CLUTTER ARE BOTH OBSERVED AFTER PULSE COMPRESSION 4HE 3#6 OF TWO RADARS CANNOT NECESSARILY BE USED TO COMPARE THEIR PERFORMANCE WHILE OPERATING IN THE SAME ENVIRONMENT  BECAUSE THE TARGET 
 1957.  45. Fried. 
 KM SWATH   OVER A VARIETY OF INCIDENT ANGLES )TS ANTENNA IS AN ACTIVE PHASED ARRAY 4ERRA3!2 
 H., J. Rheinstein. and A. 
 SUPPORTING DESIGNS IS AVAILABLE TO MINIMIZE THE ELECTRICAL EFFECTS UNDER THE CONSTRAINTS OF THE ENVIRONMENT 4HE RADOME SKIN MAY BE RIGID  SUPPORTED BY A FRAMEWORK  OR AIR 
 The bandwidth listed here is the instantaneous bandwidth of the tube, i.e., without tuning adjustments. The tube bandwidth must be compatible with system requirements; in turn, system bandwidth tends to be based on avail- able or presumed tube capabilities. X-rays. 
 Radarswhichelectronically scanabeaminelevation (usually apencilbeam) byeitherphaseshiftersorfrequency scancanstabilize thebeaminelevation asacorrection to theelevation scanorders,thuspermitting areduction inthesizeorthemount.Thestabiliza-. tiori of a pliascd array arlterltia capable of electror~ically scannir~g the beam is accomplislied ill  tlte computer that generates the stceri~tg orders.  Sor~ietirnes the terrns 1c1~~1 arid c.r.oss 1c1-cl are used to refer to the angles in a stabili7ed  system."' Tile lorel ~trgle is tlie arigle between tile horizontal plane arid the deck plarie,  rneasi~red irl tlie vertical platie tllrotrgli the line of sight. 
 OLDS SHOWN IN &IGURE   THE DETECTION PERFORMANCE SHOWN IN &IGURE   AND THE ANGULAR ACCURACY SHOWN IN &IGURE  #OMPARING (ANSENS SCANNING CALCULATION WITH THE SINGLE 
 14.15 are most useful when the different frequencies indicated are several multiples of the repetition frequency. In this event, the many harmonic lines act almost like a continuum. Such a diagram would not be useful to discover the step error shown in the phasor diagram above. 
 INDUCED PHASE VARIA 
 ING TARGET NOTCH 4HE CONCERN IN THIS REGION IS WHITE PHASE NOISE  WHICH DETERMINES THE PHASE NOISE FLOOR ,OW FREQUENCY IE  CLOSER TO THE CARRIER  STABILITY IS MORE APPLICABLE TO AIR 
 TIie display  of land clutter is also of importance in some applications so as to provide reference landmarks.)  lri pririciple. availability of color allows an intensity-modulated CRT, which is normally of  lir~iited dyriai~iic range, to display target amplitude informatiori by color coding the target blip  according to the magnitude of the target cross section. Studies show that three or perhaps  four colors is the optimum number for color display appli~ation.~~*~~ A particular four-color  display tested for air-traffic-control radar utilized yellow to present the aircraft data blocks,  gteen for the area-sector map lines, red for navigation aids, and orange for showing  pre~ipitation.~ '  The tricolor shadow-mask cathode-ray tube commonly used for color television has a  pliosphor screen that consists of a series of three color dots. 
 The simulation is conducted at 10 GHz using vertical polarization with a 45◦look-down angle. Four canonical shapes of the same size were used: a square plate dihedral set horizontally (named dihedral A), a square plate dihedral set vertically (named dihedral B), a triangular trihedral and a top-hat. The size is approximately 10 times longer than wavelength. 
 Technol. , vol. 20, pp. 
 (From Davis and Cohen,'" courtesy Elrctrotzics atd  MI T Lincoln Laboratory.)  55-ft-diameter radome shown in Fig. 7.29 is designed so that the plastic flanges between  the panels take the load while the plastic panels act as thin diaphragms which merely transmit  wind-pressure loads to the framework to which they are attached. The supporting framework  can also be of steel or aluminum members rather than plastic. 
 The VSWR of-1.5 was selected forthis definition since itisintherange usually encountered inradar systems. Pulling figures formagnetrons with comparable loading increase with frequency, since the same fractional change infrequency corresponds toalarger number dFIG.10.23 .—M.agnetron with unsymmetrical tuning cavity. ofmegacycles athigher frequencies. 
 (b) SSN = 100. Loss (dB) Frequency (MHz) or El. Angle (deg) Noise (dBW) Loss (dB) Frequency (MHz) or El. 
 INCREASING DATA BANDWIDTHS 4HESE PARALLEL PROCESSOR ARCHITECTURES OFFER THE BENEFIT OF BEING PROGRAMMABLE  USING HIGH 
  
 Echoes from nearby targets will also be attenuated; but becaitse  of the inverse fourth-power variation of signal power with range, they will usl~ally he large  enough to exceed the threshold and be detected. The receiver gain increases with time until  maximum sensitivity is obtained at ranges beyond which clutter echoes are expected. Ideally,  STC should make the average clutter power always equal to the noise power. 
   
 ING SIGNALS #OMPUTATIONAL !SPECTS AND 2AY 
 °ÎÈ  2!$!2 (!.$"//+  &OR RANGE TRACKING  IT IS NECESSARY TO RELATE RANGE NOISE TO TH E TARGET REFLECTIVITY DISTRI 
 One example of the potentially serious consequences of very strong absorption is the impact it might have on airborne storm avoidance radars, most of which are in the 3-cm band, although some use a 5-cm wavelength. Metcalf15 has examined ground-based radar data from the storm that was responsible for the 1977 crash of Southern Airways Flight 242 in northwest Georgia. The crew had relied on its on-board radar for penetration of a severe storm. 
  D"C(Z  IS ALLOCATED  TO THE CONTRIBUTING HARDWARE UNITS 4HE PERCENTAGES ARE BASED ON EXPERIENCE AND NEGO 
 GETS HAVING LOW TO HIGH RADIAL VELOCITIES 4HE SMALLER THE APPARENT RADAR CROSS SECTION OF THE TARGET  THE HIGHER THE TRUE RADIAL VELOCITY MUST BE FOR ACCEPTANCE 4HE TRUE RADIAL VELOCITY VERSUS APPARENT RADAR CROSS SECTION PROFILE IS INTENDED TO ACCEPT AIRCRAFT AND MISSILES BUT REJECT BIRDS 4HEREFORE  THREATENING TARGETS THAT  HAVE HIGH RADIAL VELOCI 
  
 M LONG TRANSVERSAL  TRACE CLOSE TO A JOINT OF A HIGHWAY CONCRETE DECK 4OP 0OLARIZATION PARALLEL TO THE DOWELS BOTTOM  0OLARIZATION PERPENDICULAR TO THE DOWELS #OURTESY )%%   #$      #$         "$ % #   $#   #    #  
 GRATION TIME OF  S  RESULTING IN A NOMINAL DOPPLER FILTER BANDWIDTH OF  (Z .OISE .  SAMPLES WERE TAKEN FROM THE MAXIMUM DOPPLER BIN  TARGET SAMPLES  4   ON THE TARGET PEAK  AND "RAGG LINE AMPLITUDES  !  AND 2  FROM THE CLUTTER PEAKS  CORRESPONDING TO THE APPROACHING AND RECEDING RESONANT OCEAN WAVES  AS DESCRIBED IN 3ECTION   .  4  !  AND 2 ARE PLOTTED IN &IGURE A  4HE SUB 
 A different approach to the problem is line-of-sight, or tilt, stabilization. Instead of mount-  ing the antenna on a level platform, the antenna is tilted about the elevation axis so as  to automatically maintain the beam pointed at the horizontal. (The beam direction can also be  maintained constant at whatever angle above or below the horizon is desired.) The line of sight  is thereby stabilized. 
 SPACE 0ROPAGATION  4HE SIMPLEST CASE OF ELECTROMAGNETIC WAVE PROPAGA 
 FIG. 17.1 Clutter and target frequency spectrum from a horizontally moving platform. the angle between the velocity vector and the line of sight to the target. 
 ?'he arc loss might be f to 1 dB in tubes filled with water vapor and 0.1 dB or less  with argon filling. On reception, the TR tube introduces an insertion loss of about f to 1 dB.  The life of a conventional TR is limited by the keep-alive, the amount of water vapor in  the gas filling, and by disappearance, or " clean-up," of the gas due to the gas molecules  becoming imbedded in the walls of the TR tubes4' The end of life of a TR tube is determined  more by the amount of leakage power which it allows to pass than by physical destruction or  wear. 
 (4.8)], but it also  allows a sharper low-frequency cutoff in the frequency response than might be obtained with a  cascade of single-delay-line cancelers with sinn nf,Tresponse.  The blind speeds of two independent radars operating at the same frequency will be  different if their pulse repetition frequencies are different. Therefore, if one radar were " blind "  to moving targets, it would be unlikely that the other radar would be " blind" also. 
 20, pp. 79-82, June, 1977.  2 1. 
 In Proceedings of the 2014 IEEE Geoscience and Remote Sensing Symposium, Quebec City, QC, Canada, 13–18 July 2014; pp. 930–933. 7. 
 . Radar System Engineeri ng Chapter 8 – Pulse Radar  55     b c fa d e Σ   Figure 8.8  Time behaviour of moving targets ( ↓) on an oscilloscope.   For automatic analysis the fact that fixed -target echoes are constant from pulse to pulse is  used. 
 Because of the spherical symmetry of l he  lens, the focusing property does not depend upon the direction of the incident wave. The beam  may be scanned by positioning a single feed anywhere on the surface of the lens or by locating  many feeds along the surface of the sphere and switching the radar transmitter or receiver from  one horn to another. The Luneberg lens can also generate a number of fixed beams. 
 4.8). The output of the IF amplifier is fed to I and  Q phase detectors. The analog signals from the phase detectors are converted into 10-bit  digital words by A/D converters. 
 TUDE DISTRIBUTION 4HE DIFFERENCE CHANNELS ARE TREATED SIMILARLY WITH INDEPENDENT AMPLITUDE WEIGHTING 4HIS METHOD MAY BE EXTENDED TO INCLUDE COMBINATIONS IN THE OTHER PLANE !MPLIFICATION ON RECEIVING OR ON BOTH RECEIVING AND TRANSMITTING MAY BE CON 
 At low-power levels, gridded tubes must compete with the  solid-state transistor.  l'he grid-corttrolled tube is characterized as being capable of high power, broadband, low  or 113oderate gain, good efficiency, atid inherent long life. Unlike other microwave tubes, the  grid-controlled tube can operate, if desired, with a linear rather than a saturated gain charac-  teristic. 
 LIMITED TECHNIQUES  OF WHICH LASER ALTIMETERS ARE EXTREME EXAMPLES  CIRCUMVENT THESE PROBLEMS  BUT MAY IMPLY THEIR OWN SET OF DISADVANTAGES ! MAJOR POTENTIAL APPLICATION OF RADAR ALTIMETRY IS TO MONITOR THE HEIGHT OF EXTENSIVE  ICE SHEETS  AS FOUND IN 'REENLAND OR !NTARCTICA !PPROXIMATELY  OF THESE LAND 
 POLAR 
 In fact, C now starts  discharging through R2 and the point M, and therefore  the potentials of G2 and G3 will change slowly untla .  state similar to (6) is reached. At this instant the slow  change in G3 and G2 voltages acts as a disturbance, and  another violent change (the ‘flop’) takes place in the  . 
 IEEE, vol. 54, pp. 237-243, February 1966. 
 TheBritishrealized theadvantages tobegainedfromthebetterangular resolution possible atthemicrowave frequencies, especially forairborne andnavalapplica­ tions.Theysuggested thattheUnitedStatesundertake thedevelopment ofamicrowave AI. 12 INTRODUCTION TO RADAR SYSTEMS  radar and a microwave antiaircraft fire-control radar. The British technical mission  demonstrated the cavity-magnetron power tube developed by Randell and Boot and furnished  design information so that it could be duplicated by United States manufacturers. 
 Mookerjee and F. Reifler, “Reduced state estimator for systems with parametric inputs,” IEEE  Trans . Aerospace and Electronic Systems , vol. 
 BOUNCE TARGETS ARE REJECTED 3UCH A SYSTEM CAN  THEREFORE  GIVE A MEASURE OF SUPPRESSION OF RAIN ECHOES   IDEALLY AMOUNTING TO    LOG E    E  
 The envelope oftheechoes istheantenna pat- tern (voltage two ways), and the maximum pulse-to-pulse variation Ay occurs atthe point where the antenna pattern has itsmaximum slope. Thus Aycan bereadily calculated ifaGaussian error curve isused asan approximation totheactual antenna curve. The result canbewritten in theform Ay 1.43 Yo=?l’(7) where y.isthemaximum received voltage and nisthenumber ofpulses transmitted while the antenna rotates through anangle equal tothe. 
 Thisfilterpassesthecluttercomponent atdc,hence ithasnoclutterrejection capability. (Itsoutputisuseful,however, insomeMTIradarsfor providing amapoftheclutter.) Thefirstnullofthefilterresponse occurswhenthenumerator iszero,orwhenf= liNT.Thebandwidth between thefirstnullsis21NTandthehalf-power bandwidth isapproximately O.9INT (Fig.4.23). Whenk=I,thepeakresponse occursat/=liNTaswellasf=liT+liNT,21T+ liNT,etc.Fork=2,thepeakresponse isatf=2INT,andsoforth.Thuseachvalueofthe indexkdefines aseparate filterresponse, asindicated inFig.4.23,withthetotalresponse covering theregionfromf=0tof=liT=/p.Eachfilterhasabandwidth of21NTas measured between thefirstnulls.Because ofthesampled natureofthesignals,theremainder of thefrequency bandisalsocovered withsimilarresponse, butwithambiguity. 
 BASED DISPLAY TECHNOLOGY )N PARTICULAR  MODERN WELL 
 2409–2412. 25. Yu, Y.; Acton, S. 
 Conv. Rec. , vol. 
 If the sidelobes  of the individual filters of the doppler filter bank can be made low enough, the inclusion of  the delay-line canceler ahead of it might not be needed.  MTIANDPULSE DOPPLER RADAR123 ingtothek=0toN-1weighting asgivenbyEq.(4.13).(Thisisanalogous togenerating N independent beamsfromanN-element arraybyuseoftheBlassmultiple-beam arrayasin Fig.8.26.)Whengenerating thefilterbankbydigitalprocessing itisnotnecessary literally to subdivide eachoftheNtaps.Theequivalent canbeaccomplished inthedigitalcomputations. Thegeneration bydigitalprocessing ofNfiltersfromtheoutputsofNtapsofatransver­ salfilterrequires atotalof(N-1)2multiplications. 
 T. Vetterling, and B. P. 
 The spectral spread in  velocity is with respect to tlie mean velocity, which for ground clutter is usually zero. Rain and  I I I I1 l Ill 1 I I I11111 I I I I1111  Sparse Wooded hills Wooded hills Sea echo Rain  woods 10 knots 40 knots Chof f -  -  -  -  -  -  I I I 1 11111 I I I 1 11 111 I I I1 1111~  uv = rms velocity spread, rn/s  Figure 4.30 Plot of double-canceler clutter improvement factor [Eq. (4.26)] as a function of a, = rms  velocity spread of the clutter. 
 The lowest mode inround guide has diametral rather than axial symmetry, FIG.11.13 .—Waveguide rotary joint using round waveguide andaxially symmetrical mode. and ifpresent toanappreciable extent will cause serious variation in voltage standing-wave ratio asafunction ofangle ofrotation. The transitions from rectangular toround guide aredesigned toavoid exciting the undesired mode asfaraspossible. 
 ELEVATION ANTENNA BEAM USED FOR MONOPULSE ANGLE ESTIMATION  D"C  DECIBELS WITH RESPECT TO THE CARRIER$#  DIRECT CURRENT$&4  DISCRETE &OURIER TRANSFORM&)'52%   3INGLE 
 Appl. Meteorol. ,   vol. 
 136-138  quantization, 120  Efficiency: klystron. 204 tube.191 Electromechanical phaseshifters.297-298 Electron-bombarded semiconductor (EBS) device.21721R Electron gun.201 Electronic counter-countermeasures. 542. 
 TO 
 TION FOR AIRCRAFT TRACKING IN THE UPPER PART OF THE (& BAND 4HE EXPERIMENTAL &RENCH /4( RADAR .OSTRADAMUS n LIKEWISE EMPLOYS A SINGLE ANTENNA ARRAY  CONFIGURED AS  THREE HORIZONTAL ARMS OF LENGTH  M RADIATING FROM A CENTRAL CONTROL CENTER  THOUGH ONLY A SUBSET OF ELEMENTS ARE USED TO TRANSMIT  WHEREAS ALL OF THE ELEMENTS ARE USED FOR RECEPTION 3UCH TRULY MONOSTATIC DESIGNS HAVE THE SPECIAL ADVANTAGE THAT THE OUT 
 REFLECTED SIGNAL CAN INCREASE SIGNIFICANTLY THE RANGE OF A 6(& RADAR 3OMETIMES THIS EFFECT CAN ALMOST DOU 
 TUDE TO SEVERAL INDIVIDUALS WHO HELPED THEM IMMENSELY IN THE PREPARATION OF THIS CHAPTER &IRST  TO -R 'REGORY 4AVIK OF .2, FOR HIS THOROUGH REVIEW OF THIS CHAPTER AND THE MANY EXCELLENT COMMENTS HE MADE .EXT  TO $R &RED (ARRIS OF 3AN $IEGO 3TATE 5NIVERSITY AND -R 2ICHARD ,YONS  WHO GRACIOUSLY REVIEWED SECTIONS OF THE CHAPTER AND OFFERED SEVERAL SUGGESTIONS  ALL OF WHICH WERE INCORPORATED , 
 13065–13083, 1986. 32. A. 
 SHOULDER GEOMETRY OR WHEN THE BASELINE IS SMALL )N THESE CASES  TRANSMIT AND RECEIVE BEAMS BECOME MORE CLOSELY ALIGNED IN A . 
 (14.2) into(14.1)givesthecross-range resolution as bcr=RA/D Thebeamwidth ofasynthetic aperture antenna ofeffective lengthLeissimilarly 0$=klJ2Le(143) (14.4) Thefactor2appears inthedenominator becauseofthetwo-way propagation pathfromthe .1Iltenna "element" tothetargetandbackascompared withtheone-way pathofaconven­ tit,nalantenna. Asaconsequence ofthetwo-way paththephasedifference between theequally spacedelements ofasynthetic arrayistwicethatofaconventional arraywiththesame spacing. (Thetermssynthetic arrayandsynthetic aperture areusedinterchangeably here.) Againthefactorkwillbetakentobeunity. 
 I. I. Kat1, and L. 
 Thetwo-frequency CWtechnique formeasuring rangewasdescribed asusingthedoppla frequency shift.Whenthedoppler frequency iszero,aswithastationary target,itisalso possible, inprinciple, toextractthephasedifference. Ifthetargetcarriesabeaconorsome otherformofecho-signal augmentor, thedoppler frequency shiftmaybesimulated bytrans­ latingtheechofrequency, aswithasingle-sideband modulator. Thetwofrequencies ofthetwo-frequency radarweredescribed asbeingtransmitted simultaneously.63 Theymayalsobetransmitted sequentially insomeapplications byrapidly switching asingleRFsource. 
 E. Ruvin, “Recent advances in the synthesis of comb filters,” in IRE Nat.  Conv. 
 179. G. A. 
 This was due to variations in the equipment itself and also to component failures, poor tuning and so on. The effects of radar propagation and sea returns, which were only just beginning to be understood, and variations in targetradar cross section also contributed. Also very signi ﬁcant were the great variations in operator skill levels and the lack of concentration during long operations due to fatigue. 
 Another significant application of radar that depends on the doppler shift is obser - vation of the weather, as in the Nexrad radars of the U.S. National Weather Service  (Chapter 19) mentioned earlier in this chapter. Both the SAR and ISAR can be described in terms of their use of the doppler fre - quency shift (Chapter 17). 
 DETECTION IMAGERY  FOCUSED 3!2  DATA MAY BE PRE 
 TO 
 '(Z PERFORMANCE CURVES FOR A  MM  PERIPHERY 'A!S 0(%-4 &%4 OPERATING AT    6 USING A #7   DUTY  WAVEFORM.   3/,)$ 
 The stretch processing implementation for the Millimeter  Wave radar (MMW) located at Kwajalein Atoll is described by Abouzahara and  Avent.64 The MMW radar operates at a carrier frequency of 35 GHz using waveforms  with a maximum swept bandwidth of 1000 MHz and pulsewidth of 50 µs. The LFM  slope for the transmit waveform is  αµµ = = =B T100020MHz 50sMHz/s  The stretch processing bandwidth is Bp = 5 MHz. The width of the stretch processing  time window is   ∆t= =50 25MHz 20MHz ssµµ. 
 38.Peeler,G.D.M.,andD.H.Archer:AToroidal Microwave Reflector, IRENelli.Conr.Rt'Cord,vol.-t, pt.I,pp.242-247, 1956. 39.Kelleher, K.S.,andH. H.Hibbs:ANewMicrowave Reflector, Nal'alResearch Lah.Rept.4141,1953. 
 MIT-9, pp.472-480, November, 1961. 47.Knerr,R.H.:AnAnnotated Bibliography ofMicrowave Circulators andIsolators: 1968-1975,/EEE Trans.,vol.MIT-23, pp.818-825, October, 1975. 48.Gawronski, M.J.,andH.Goldie:200WMICL-BandReceiver Protector, Microwave J.,vol.20,pp. 
 CIVIL MARINE RADAR  22.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 can be initiated. All tracked targets are displayed on the screen with their associated  velocity vectors. Tracked targets may be selected by the user such that all information  concerning that target, including CPA and TCPA, is displayed on the data panel of the  radar screen. 
 PLY ANDOR MODULATOR DELIVERING POWER TO THE TUBE 3INCE  * OF ENERGY CAN USUALLY CAUSE DAMAGE TO AN 2& TUBE OR THE SWITCHING DEVICE  AND SINCE THE CAPACITOR BANK FOR AN ACTIVE 
 A rectangular display in which a target appears as a laterally centralized blip when the radar  antenna is aimed at it in azimuth, and wings appear to grow on the pip as the distance to the target is  diminished; horizontal and vertical aiming errors are respectively indicated by horizontal and verti­ cal displacement of the blip.  fl-scope. A B-scope modified to include indication of angle of elevation. 
 HERTZ PHASE ;SIGNAL= FOR EACH BASELINE PAIR   EAST WEST AND  NORTH SOUTH  4HIS PHASE SIGNAL IS COMPARED WITH A  
 M.: "Probability and Information Theory, with Applications to Radar," chap. 6,  McGraw-Hill Book Co., New York, 1953.  6. 
 TION OF ENERGY WITHIN A SLENDER FICTITIOUS TUBE CALLED A  RAY 4HE DIRECTION OF PROPAGATION  IS ALONG THE TUBE  AND CONTOURS OF EQUAL PHASE ARE PERPENDICULAR TO IT )N A LOSSLESS  MEDIUM  ALL THE ENERGY ENTERING THE TUBE AT ONE END MUST COME OUT THE OTHER END  BUT ENERGY LOSSES WITHIN THE MEDIUM MAY ALSO BE ACCOUNTED FOR !N INCIDENT WAVE MAY BE REPRESENTED AS A COLLECTION OF A LARGE NUMBER OF RAYS  AND WHEN A RAY STRIKES A SURFACE  PART OF THE ENERGY IS REFLECTED AND PART IS TRANSMITTED ACROSS THE SURFACE 4HE AMPLITUDE AND PHASE OF THE REFLECTED AND TRANSMITTED RAYS DEPEND ON THE PROPERTIES OF THE MEDIA ON EITHER SIDE OF THE SURFACE 4HE REFLECTION IS PERFECT IF THE SURFACE IS PERFECTLY CON 
 FREQUENCY AND NEGATIVE 
 Animportant advantage ofthe limiting receiver isthat the output video signals have ai-ange ofamplitude extending from noise only upto the limit level. This small dynamic range makes iteasy todesign the cancellation circuits. For thelin-log receiver, thedynamic range is6to 12dbgreater under conditions ofequal performance. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.90  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 by the maximum likelihood estimate.49 For a single-pulse signal-to-noise ratio S1  and n pulses in a CPI, the Cramer-Rao lower bound for the accuracy of the doppler  frequency estimate is  σ πf S n n S n n PRF= ⋅ ⋅ ⋅ ⋅ −= ⋅ ⋅ −6 2 103898 112 12( ). ( ) (2.65) Since the maximum likelihood estimation procedure tends to require a tedious  computational burden, a simplified approach for estimating the doppler frequency is  highly desirable. 
 TRACK ASSOCIATION )T IS POSSIBLE TO MAKE SIMPLE COMPARISONS BETWEEN THE ACCURACY OF DETECTION FUSION  AS OPPOSED TO TRACK FUSION FOR EQUIVALENT USE OF DATA BANDWIDTH TO EXCHANGE RADAR DATA 7HEN 2/5 IS PLOTTED AS A FUNCTION OF THE POSITION GAIN  @  IT HAS THE hBATHTUBv SHAPE  SHOWN BY THE SINGLE RADAR CURVE IN &IGURE  4HE LEFT 
 ING VERY HIGH ANTENNA GAINS ARE   MISSILE DEFENSE RADAR AND   SPACE 
 TAL CONDITIONS FOUND ON SMALL CRAFT )NSTEAD  MINI JOYSTICKS OR SIMPLE FOUR 
 Figure 3.4  Refraction of waves in the inhomogeneous atmosphere and the enlargem ent of the  range of coverage.   . Radar System Engineering  Chapter 3 – The Radar Equation  17     Through this bending, as it is taken into account in physical optics, the visibility & view under  the horizon with be expanded. 
 Plant, and W. C. Keller, “Comparison of optically-derived  spectral densities and microwave cross-sections in a wind-wave tank,” J. 
 With other  phase and frequency relationships, there is still a loss with a single channel MTI that can be  recovered by the use of both the I and Q channels. An extreme case where the blind phase with  only a single channel results in a complete loss of signal is when the doppler frequency is half  the prf and the phase relationship between the two is such that the echo pulses lie on the zeros  or the doppler-frequency sine wave. This is not the condition for a blind speed but nevertheless  there is no signal. 
 E. Willey54 © IRE 1962.  Courtesy of  Bendix Radio .) ch13.indd   23 12/17/07   2:39:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Ithas proved, however, tobenooperational limitation. Height-finding bysuch asetisreasonably accurate. The results ofa calibration flight with anexperimental model ofthe AN/T PS-10 are shown inFig. 
 --" Ê76 
 181. R. K. 
 Pulses from theupper half oftheantenna rotation arecompared with those from the lower half bymeans ofinte- grating circuits, and theoutput difference isused todisplace thespot ofan error indicator (Sec. 6.8). APPI isprovided forgeneral reporting, and two range scopes, one covering the full range ofthe setand one an expanded A-scope, make itpossible todetermine target range and to eliminate from thesignal-comparison circuits allechoes except those from thetarget whose altitude isbeing determined. 
 -  !S DISCUSSED IN 3ECTION   THE -4$ USES A WAVEFORM CONSISTING OF COHERENT PRO 
 TIPLE RECEIVE ANTENNA CHANNELS AND PULSES 4HIS WEIGHTING DYNAMICALLY TAILORS A FILTER RESPONSE IN ANGLE AND BISTATIC DOPPLER TO SUPPRESS GROUND CLUTTER REFLECTIONS $IGITAL BEAMFORMING   IS REQUIRED FOR THIS OPERATION /THER NECESSARY ELEMENTS INCLUDE A  MEANS TO ESTIMATE THE SPATIO 
 Houze, Jr., and J. D.  Locatelli, “Real-time wind measurement in extratropical cyclones by means of doppler radar,”   J. 
 However, there is a loss of 3 dB SNR at the receiver inputs although this loss is partly regained by coherent addition of the 2-signal information. The design of the microwave resolver must minimize loss through the device, and high preci- sion is required to minimize cross coupling between azimuth and elevation chan- nels. The resolver performance is improved by the use of ferrite switching de- vices to replace the mechanical rotating coupler. 
 ART OF  RADAR CAN AMELIORATE THESE PROBLEMS  BUT NOT WITHOUT SOME UNDESIRABLE SIDE EFFECTS -ANY UNWANTED POINT TARGET RETURNS HAVE CHARACTERISTICS SIMILAR TO THE RETURNS FROM WANTED TARGETS  AND THE UNWANTED RETURNS MAY OUTNUMBER RETURNS FROM DESIRED TAR 
 Óä°{  2!$!2 (!.$"//+  #ONSIDER THE SET OF TASKS AND $)2S SHOWN IN &IGURE  4ASK  WOULD REQUIRE ONLY  SHORT #)4S  n S  SAY  IF THE AIRCRAFT IS ASSUMED TO BE LARGE  AND WOULD NEED REVISITS  PERHAPS EVERY MINUTE  AS THE FLIGHT IS NOT EXPECTED TO MANEUVER SO THE TRACK WILL BE WELL 
 IEC has no responsibility for the placement and context in which the extracts and  contents are reproduced by the author, nor is IEC in any way responsible for the  other content or accuracy therein. REFERENCES  1. International Maritime Organization, www.imo.org. 
 J8. Barbe, D. F., and W. 
 More recent optical ﬂow or motion estimation algorithms can be investigated as an alternative to the one utilized in this work. The chosen optical ﬂow method is suitable for the tested dataset and performs adequately as expected since it takes into account the intensity changes between images. The choice of K-SVD over PCA increased the computational complexity while allowing ﬂexibility over the details of the change maps by changing the dictionary size and the number of non-zero coefﬁcients. 
 56. Works, G. A.: Advanced Onboard Signal Processor, IEEE EASCON '8O Rec., p. 
 Unlike vacuum tubes, the peak power that  c;irl hc ;icliicvcd wit 11 Itarrow pillse widtlis is only about twice the CW power.28 This res~rlts in  tlic tnicrowave trntisistor t~citig operated with relatively long pulse-widths and high duty  cyclcs. For air-s~~r.vcill;iricc radar applic;itio~l. pulse widtlis rniglit be many tetis of  r~lic~~oscculicls or niorc. 
 vol. 36,  pp. 1652-1660, 1958. 
 SIDELOBE ANTENNA CAN BE CONSIDERED IN TWO PARTS  #HOOSE THE CORRECT ILLUMINATION FUNCTION TO ACHIEVE THE DESIRED DESIGN ERROR 
 MATICALLY WITH ONLY MODEST DEPARTURES FROM OPTIMUM SETTINGS 4HUS  THERE IS A DEMAND FOR TWO INGREDIENTS I  INFORMATION ABOUT THE ENVIRONMENT AND II  A MECHANISM  OR AT LEAST A STRATEGY  FOR USING THAT INFORMATION TO CONTROL THE RADAR PARAMETERS !T THE VERY MINIMUM  (& SKYWAVE  RADARS MUST MAINTAIN A REAL 
 Leung, Z. Hu, and M. Blanchette, “Evaluation of multiple radar target trackers in stressful  environments,” IEEE Trans . 
 ch06.indd   25 12/17/07   2:03:25 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 WAY PROPAGATION WITH RESPECT TO TWO 
 SURVEILLANCE NEEDS 4HEY HAVE BEEN DESIGNED FOR REMOTE  OPERATION IN HARSH ENVIRONMENTS  AND WITH THEIR ESTABLISHED LOGISTICS SUPPORT  BUILT 
 Application to live data acquired with a ground-based phased array radar,” Proc. of IEEE 2004  Radar Conf ., Philadelphia (USA), April 26–29, 2004, pp. 486–491. 
 Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar.  PULSE DOPPLER RADAR  4.516x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 29. A. 
 In addition to external sources of interference, the radar designer must be con- cerned with internal signal sources. MTI and pulse doppler radars are particularly dB BELOW OUTPUT AT CENTER OF PULSE RELATIVE VOLTAGE NINE-POLE GAUSSIAN INFINITE-POLE GAUSSIAN FIVE TUNED STAGESRECTANGULAR FIVE-POLE GAUSSIAN ONESINGLE-TUNEDSTAGE TWO TUNEDSTAGES . susceptible to any such internal oscillators that are not coherent, i.e., that do not have the same phase for each pulse transmission. 
 PL PLSSIN SIN  PP 
 For a given antenna size (antenna aperture), narrower beam widths are obtained when using shorter wavelengths. For a given wavelength, narrowerbeam widths are obtained when using larger antennas. The slotted waveguide antenna has largely eliminated the side-lobe problem. 
 For good range resolution, TT must be small, which requires that An1 be large. (Target range change during the dwell limits the minimum T,.) 5. To minimize the transmitter duty cycle and hence the average-power vari- ation between PRFs, An1 should be relatively large. 
 FREQUENCY RADARS  BUT THE DOPPLER RESOLUTION CAN BE EXCEEDINGLY FINE 4HE MAGNITUDE AND DOPPLER DISTRIBUTION OF THE ECHOES FROM THE DISTANT %ARTHS SURFACE OFTEN TERMED  BACKSCATTER   THOUGH THAT TERM SHOULD BE RESERVED FOR MONOSTATIC RADARS  ARE MAJOR FACTORS IN SETTING SYSTEM DYNAMIC RANGE  SPECTRAL PURITY  AND SIGNAL PROCESSING REQUIREMENTS#HAPTER . Óä°Ó  2!$!2 (!.$"//+  &OR EFFECTIVE RADAR OPERATION  ENVIRONMENTAL PARAMETERS THAT AFFECT RADAR PERFORMANCE  NEED TO BE DETERMINED IN REAL TIME  DEFINED AS THAT INTERVAL IN WHICH THERE ARE NO LARGE 
 The received Y*  pulse train of finite duration to has a frequency spectrum (which can be found by taking the  Fourier transform of the waveform) whose width is proportional to l/to. Therefore, even if the  clutter were perfectly stationary, there will still be a finite width to the clutter spectrum because  of the finite time on target. If the clutter spectrum is too wide because the observation time is  too short, it will affect the improvement factor. 
 G. Long, and A. W. 
 (after T. LeToan12 © IEEE 1982 ) ch16.indd   38 12/19/07   4:56:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 PROCESSED MONOLITHIC MICROWAVE INTEGRATED CIRCUITRY --)#  FABRICATION TECH 
 Performance Requirements.—As always, the range performance ofthe radar was the principal initial requirement. The following ranges (innautical miles) onvarious targets were taken asbeing comfortably over theminimum necessary fornavigation even ofahigh-speed airplane. Ground painting ....................25 t030 Cities ............................30 t050 Storm clouds ................... 
 This usually sets anupper limit tothe number ofturns that can beused within the bounds ofa reasonable power supply voltage. These and other matters pertaining tocoil design are discussed at length inVol. 22oftheseries. 
 61. E. M. 
 Based 186. Sensors 2019 ,19, 2161 on the law of large number, the scintillation phase error tends to follow the Gaussian distribution. Thus, the Gaussian approximation can be used to simplify the TFTPCF, which is expressed as follows. 
 Jerinic and M. Borkowski, “Microwave module packaging,” in IEEE Microwave Theory and  Techniques Symposium Digest , 1992, pp. 1503–1506. 
 Major airports employ an Airport Surveillance Radar (ASR) for observing  the air traffic in the vicinity of the airport. Such radars also provide information about  nearby weather so aircraft can be routed around uncomfortable weather. Major airports  also have a radar called Airport Surface Detection Equipment (ASDE) for observing  ch01.indd   21 11/30/07   4:34:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 WAVE TRANSISTORS FROM UNDESIRED OPERATIONAL STRESSES  AND THEIR HARMONIC POWER OUTPUT MUST BE PROPERLY FILTERED TO MEET -), 
 October. 1974. 100 INTRODUCTION TO RADAR SYSTEMS  57. 
 - &)'52%   4IME 
 1, 1958, pp. 202–211. ch03.indd   33 12/15/07   6:03:35 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The output of the matched filter will be a spike of width r with an amplitude N  times greater than that of the long pulse. The pulse-compression ratio is N = T/r = BT, where  B = llr = bandwidth. The output waveform extends a distance T to either side of the peak  response, or central spike. 
 -ISSION 3URVEILLANCE 2ADAR --32  FAMILY OF !4# RADARS BUILT BY ,OCKHEED -ARTIN #O .ONLINEAR &- WAVEFORMS ARE USED BECAUSE THE TARGETS OF INTEREST HAVE RELATIVELY LOW DOPPLER SHIFTS LESS THAN -ACH   ,IKE THE !.&03 
 .4.Waveguide 1*X3 ixli *X1 ix% B.Rigid coaxial lines, stub- Csupported Outer l; Inner ~ Outer ~ Inner ~ Outer + Inner & Flexible coaxial cable, RG- 9/U, polyethylene dielec- tric Dielectric OD0.280 in. Inner conductor 7strands #21.4VVG, Outer conductor double braidWall, i:,. .0.080 0.06!! 0.050 0,040 0.049 0.035 0.032 0.03” 0.032 0.032Wave- mgth, crr 10.0 3,2 3.2 1.25 10.0 10.0 3.2 ‘IO.O ,3.2,faximur power, * MW 10.5 1.77 0.99 0,22 4.2 1.3 0.36 0.31$ 0.31$attenua- tion, t db/ra 0.039 0.15 0.24 o.5~ 0.08 0.15 0.49 0.56 1.12)Wave- length rrrnge, cm 7.6-11,8 3,+4.7 2.4-3,7 1.1–1.7 9.3-11,7 9.1–11.7 3.1-3.5 3.o-@ ●Comnuted formaximum gradient of30kv/cm. 
 Hommel and H. Feldle, “Current status of airborne active phased array (AESA) radar   systems and future trends,” in 2005 IEEE MTT-S International Microwave Symposium Digest,   June 12–17, 2005, pp. 1449–1452. 
 I I'----1' ---._'_+_~......1 -i-1 ITIi: !IrI;r I:: I:! " -1.6..',,'.. ,I,! I, --J i 'I',' J!. 11;' FPS'~'6 .-.f---'----'-[' I+---...,...T-;----1---+-1-1--- -~4--i'-'- --....-.--.'-It._ ---~ _.~.-' AZIMUTH tOEGREES) '-.......:32.547' .:''30.684 . 
 (b) Sum-delta monopulse sensitivity factor. Antenna height = 2 x aperture height; monopulse beams boresighted at H0 = 0.5; reflection coefficient = - 1. (c) Squinted-sum low-angle bias error. 
 Alabarrta, Teci~r~ical  Rt~port RR-77-3, November. 1976. (Distribution unlimited.)  88. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 14.46  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 65. 
 Goodrich, and K. M. Siegel: A Theoretical Method for the Calctrlariori of tile  Radar Cross Sections of Aircraft and Missiles, Utlirl. 
 a peak value of N9 where N is the number of subpulses in the sequence and T is the time duration of each subpulse. Hence the peak-sidelobe-voltage ratio is AT1. For the aperiodic case, the average sidelobe level along the time axis is -1A. 
 SURFACE RADAR MODE SUITE  . 
 Dashed curve gives onsct of grating  lobe for tl = 0.5A0; dot-dash curve for d = 0.6A0.  travel down the transmission line. The finite time implies a finite bandwidth. 
 34-37, April, 1976.  69. Acker, A. 
 November. 1976. 55.Clapp,R.E.:ATheoretical andExperimental StudyofRadarGround Return.,\fITRadialioll Laboratory Rept.1024,April.1946. 
 BASED MICROWAVE ASSETS WILL CONTINUE TO BE USED FOR THE FORESEEABLE FUTURE TO PROVIDE THESE DATA 4HE SUCCESS OF 3EA7INDS DISCUSSED LATER IN THIS SECTION  SUGGESTS THAT THE CONICAL SCAN PARADIGM WILL BE THE BASIS FOR FUTURE VECTOR WIND SCATTEROMETER DESIGN 4HAT SAID  THERE ARE TWO SPACE 
 Figure 4.27. Radar operator ’s compartment in a Sunderland Mk. III. 
 However, such an assumption applied blindly to computations involving inverse probability  can sometimes lead to erroneous and contradictory conclusions. 29 This difficulty in specifying  the a priori probability was recognized by Woodward and Davies.27 They suggest, however,  that the a priori factor be omitted from the inverse-probability specification when it is doubt­ ful, and in practice it may be supplied subjectively by the human observer. This merely begs  the question, for it has not been proved that an operator can supply the necessary a priori  probability, and in addition, there are many applications where no operator is involved in  making the detection decision. 
 K. Barton, private communication, June 2006. 32. 
 This multiplexed transmission scheme implies that the radar’s PRF must be  doubled to satisfy the minimum Nyquist sampling rate simultaneously for each pair of  transmissions. Doubled PRF implies that the average radiated power must be doubled  and the unambiguous range swath is halved, both in comparison to the standard case  of transmitting only one polarization. Note that the average data rate is the same as the  dual-polarized case, since twice as much data are collected by a quad-pol mode for  each resolved point in the scene, but the swath width is smaller by a factor of two. 
 A parallel-line  configuration with 16 lengths of line provides a phase quantization of 22.5" ( + 1 1.25"), assum-  ing the rrth line is of length tt,I/16. A suitable form of switch is the semiconductor diode. The  diodes attached to the ends of the particular line selected are operated with forward bias to  present a low impedance. 
 NOISE RESPONSE OF A NORMAL LINEAR RECEIVER FOR THE SAME TARGET 4HUS  ALL THE RESPONSE CURVES ARE NORMALIZED WITH RESPECT TO THE NOISE POWER GAIN FOR THE GIVEN CANCELER CONFIGURATION 4HE INTERSECTION AT THE ORDINATE REPRESENTS THE NEGATIVE DECIBEL VALUE OF  )  THE -4) IMPROVEMENT FACTOR FOR A POINT  CLUTTER TARGET PROCESSED IN A LINEAR SYSTEM&)'52%  4WO 
 ANE-11, pp. 218–223, December 1964. 11. 
 This  graph shows the signal-to-clutter ratio improvement against clutter at zero doppler as  a function of target doppler frequency. Only the response of the filter providing the  greatest improvement is plotted at each target doppler. For comparison the optimum curve from Figure 2.25 is shown by a broken line and  thus provides a direct assessment of how well the Chebyshev filter design performs  against a given clutter model. 
 With proper radar design and manage-  ment it should be possible to achieve a propagation path reliability comparable to that of a  microwave radar. This requires a large frequency range of operation, high power to overcome  propagation losses, and diagnostics of the ionospheric conditions to determine proper radar  parameters.  Example capabilities. 
 0ALMER         2$ :     :  FOR .EXRAD 732 
 This type of closed-loop adaptive MTI  must, therefore, be operated for a finite set (batch) of pulses to ensure that this will not  happen. Such batch-mode operation is also required if a combination of MTI operation  and frequency agility is desired. If a bimodal clutter situation is caused by the simultaneous presence of returns from  land clutter and weather or chaff, an adaptive MTI can be implemented following a  fixed-clutter-notch MTI section, as illustrated in Figure 2.86. 
 £ä°£{  2!$!2 (!.$"//+  £ä°ÎÊ   
  OR INTER 
 ByOctober, 1939, orderswereplacedforamanufactured versioncalledtheCXAM. Nineteen oftheseradars wereinstalled onmajorshipsofthefleetby1941. TheUnitedStatesArmySignalCorpsalsomaintained aninterestinradarduringthe early1930s.7Thebeginning ofseriousSignalCorpsworkinpulseradarapparently resulted fromavisittoNRLinJanuary, 1936.ByDecember ofthatyeartheArmytesteditsfirstpulse radar,obtaining arangeof7miles.Thefirstoperational radarusedforantiaircraft firecontrol wastheSCR-268, available in1938!8TheSCR-268 wasusedinconjunction withsearchlights forradarfirecontrol.Thiswasnecessary becauseofitspoorangularaccuracy. 
 7'1ie two-axis rnount of Fig. 7.31h, sometimes called an az-el mount, enables the beam to  he rnairitairied at the horizontal or at any angle above or below the horizon (line-of-sight  stabili7ation). The beam can be directed to any point by the proper combination of azimutli  (train) and elevation angles. 
     . £°{  2!$!2 (!.$"//+  MISSILE TO A TARGET OR THE RADAR OUTPUT MIGHT BE FURTHER PROCESSED TO PROVIDE OTHER  INFORMATION ABOUT THE NATURE OF THE TARGET 4HE  RADAR CONTROL INSURES THAT THE VARIOUS  PARTS OF A RADAR OPERATE IN A COORDINATED AND COOPERATIVE MANNER  AS  FOR EXAMPLE  PROVIDING TIMING SIGNALS TO VARIOUS PARTS OF THE RADAR AS REQUIRED 4HE RADAR ENGINEER HAS AS RESOURCES  TIME THAT ALLOWS GOOD DOPPLER PROCESSING   BANDWIDTH FOR GOOD RANGE RESOLUTION   SPACE THAT ALLOWS A LARGE ANTENNA  AND  ENERGY FOR  LONG RANGE PERFORMANCE AND ACCURATE MEASUREMENTS %XTERNAL FACTORS AFFECTING RADAR PERFORMANCE INCLUDE THE  TARGET CHARACTERISTICS EXTERNAL NOISE  THAT MIGHT ENTER VIA THE  ANTENNA UNWANTED  CLUTTER ECHOES FROM LAND  SEA  BIRDS  OR RAIN  INTERFERENCE FROM OTHER  ELECTROMAGNETIC RADIATORS AND PROPAGATION EFFECTS DUE TO THE EARTHS SURFACE AND ATMO 
 42, p. 1189, July, 1954.  13. 
 This noise power, in turn, can be expressed in terms of a receiving-system noise temperature Ts\ Pn = kTsBn (2.4) where k is Boltzmann's constant (1.38 x 10~23 Ws/K) and Bn is the noise band- width of the receiver predetection filter, hertz. (These quantities are defined more completely in Sees. 2.3 and 2.5.17) Therefore, Pr = (SIN) KT8Bn (2.5) This expression can now be substituted for Pr in Eq. 
 R. W. Bogle. 
 , 4HE BISTATIC RADAR CROSS SECTION OF SURFACE CLUTTER   RC  IS A MEASURE  AS IS THE MONOSTATIC  RADAR CLUTTER CROSS SECTION  OF THE ENERGY SCATTERED FROM A CLUTTER CELL AREA   !C  IN THE DIREC 
 51-67.  79. Kriittel, G. 
 For both sum and difference patterns, the sidelobes are referenced to the  peak of the sum pattern. The beamwidth factor provides the beamwidth, in degrees, of  an aperture with length a. Figure 13.17 gives the approximate loss in gain and the beamwidth factor for the  Taylor illumination as the sidelobes change. 
 For all practical purposes, an image placed on a storage  tube will remain indefinitely until erased.  Table 9.1 Radar CRT phosphor characteristics (after   erg^^)  Phosphor Fluorescent color Phosphorescent color Persistence*  P 1 Yellowish green Yellowish green Medium  P7 Blue Yellowish green Blue, medium short;  yellow, long  PI2 Orange Orange Long  P13 Reddish orange Reddish orange Medium  P14 Purplish blxe Yellowish orange Blue, medium short;  yellowish orange, medium  P 17 Blue Yellow Blue, short; yellow, long  PI9 Orange Orange Long  P2 1 Reddish orange Reddish orange Medium  P25 Orange Orange Medium  P26 Orange Orange Very long  P28 Yellowish green Yellowish green Long  P3 2 Purplish blue Yellowish green Long  P3 3 Orange Orange Very long  P34 Bluish green Yellowish green Very long  P38 Orange Orange Very long  P39 Yellowish green Yellowish green Long  * Persistence to 10 percent level: short = 1 to 10 ps; medium short = 10 ps to I ms;  medium = 1 to 100 ms; long = 100 ms to 1 s; very long = > 1 s.  356INTRODUCTION TORADAR SYSTEMS persistence required inacathode-ray-tube screendepends upontheapplication. 
 Ulaby150) ch16.indd   45 12/19/07   4:56:12 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 STANDING 
 Comparison of Theoretical and Estimated Chirp Relative Bandwidth. V alue Theoretical Relative Bandwidth 0.8178 Estimate of the Relative Bandwidth 0.8164 Figure 9. Range Doppler algorithm. 
 An 0TH radar designed for the detection of aircraft at ranges out to 4000 km might have,  for example, an average power of several hundreds of kilowatts or more, antenna gains from  about 20 to 30 dB, and operating frequencies from several megahertz to several tens of  megahertz. Antennas must be large in order to obtain reasonably narrow beamwidths. The  antenna horizontal length might be 300 m or greater. 
 against the residue from strong clutter. This CFAR is provided in the typical MTI system by IF limiting or, in the MTD implementation, through the use of high- resolution clutter maps. Filter Mismatch Loss. 
 PONENT IN THIS RADAR OPERATING REGIME 1UITE CLEARLY  AN UNDERSTANDING OF SEA CLUTTER IN ALL ITS ASPECTS WILL BE A CONSIDERABLE UNDERTAKING &ORTUNATELY  A CLOSE RELATION 
 TIES AND CHARACTERISTICS THAN RADARS IN OTHER FREQUENCY BANDS 'ENERALLY  LONG RANGE IS EASIER TO ACHIEVE AT THE LOWER FREQUENCIES BECAUSE IT IS EASIER TO OBTAIN HIGH 
 There does not appear to be a satisfactory model of the available data. However, general trends are apparent for all polarizations. First, aB° usually ap- proaches a minimum as <|> approaches 90°, with values 10 to 20 dB below the monostatic value (0, = 0^, <j> = 180°). 
 Skolnik. — 2nd ed. p. 
 SCALE ROUGHNESS 4HE LARGE 
 476 4XI. Fchruary, 1958.  67. 
 The amplitudes of the samples  on the leading and lagging halves of the pulse are compared for range-error sensing  similar to the comparison of amplitudes in the early-late-gates range tracker . ch09.indd   21 12/15/07   6:07:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Note, however, that sufficient pulses must be transmitted to ini- tialize the filter before useful outputs may be obtained. For example, with a three-pulse binomial-weight canceler, the first two transmitted pulses initialize the canceler, and useful output is not available until after the third pulse has been transmitted. Feedback or infinite impulse response (IIR) filters would not be used with a step-scan system because of the long transient settling time of the filters. 
 AP-24, pp. 269 276, May. 1976. 
 1456-1459, October, 1956.  45. Monaghan, S. 
 FIELD AMPLIFIERS HAVE BEEN USED IN RADARS IN THE PAST  BUT THEY HAVE SIGNIFI 
 The electrons emitted from the cathode. under the action of the crossed electric and  magnetic fields, form into rotating electron (space-charge) bunches, or spokes. These bunches  <lrift along the slow-wave circuit in phase with the RF signal and transfer energy to the RF  wave to provide amplification. 
 Smith, and A. J. Kramer: Prediction of HF Noise Directivity from Thunderstorm Probabilities, GTE Sylvania Rept. 
 ATION OF THE ATMOSPHERIC WATER 
 4nother important factor that must be considered in the radai equation is the statistical or  unpredictable nature of several of the parameters. The minimum detectable signal S,,, and the  target cross section cr are both statistical in nature and must be expressed in statistical terms.  (2.1)CHAPTER TWO THERADAR EQUATION 2.1PREDICTION OFRANGE PERFORMANCE i Thesimpleformoftheradarequation derivedinSec.1.2expressed themaximum radarrange Rmu.intermsofradarandtargetparameters: Rmu.=[r'~2Ae(J] 1/4 41tSmln wherePt=transmitted power,watts G=antenna gain Ar=antennaeffective aperture, m2 (J=radarcrosssection,m2 Smln=minimum detectable signal,watts Alltheparameters aretosomeextentunderthecontroloftheradardesigner, exceptforthe targetcrosssection(J.Theradarequation statesthatiflongrangesaredesired,thetransmitted powermustbelarge,theradiated energymustbeconcentrated intoanarrowbeam(high transmitting antenna gain),thereceived echoenergymustbecollected withalargeantenna aperture (alsosynonymous withhighgain),andthereceivermustbesensitive toweaksignals. 
 The particles are arranged in  some particular configuration in a three-dimensional lattice. The dimension of the particles in  the direction parallel to the electric field as well as the spacing between particles should be  small compared with a wavelength. H these conditions are met, the lens will be insensitive to  frequency. 
 T able 1. The parameters of four SAR images. Image Image01 Image02 Image03 Image04 Product TerraSAR-X Gaofeng-3 Gaofeng-3 Airborne Mode Strip UFS UFS Strip Resolution (M) 3 3 3 0.5 PRF (Hz) 3472.134984 2014.078491 1977.984863 500.0000 Band (MHz) 120.00 80.00 80.00 150.00 Polarization VV HH HH HH Wave Length (m) 0.031040 0.055517 0.055517 0.056564 Slant-Range (km) 629.17 7127.22 7137.52 4.62 Velocity (m/s) 7088.636524 7563.162316 7568.372931 55.599743 The SAR image perform ships detection with software [ 36] and sub-images containing defocused ship are selected in advance. 
 Chen, H.; Wang, Z.; Liu, J.; Yi, X.; Sun, H.; Mu, H.; Li, M.; Lu, Y. Knowledge-Aided Doppler Beam Sharpening Super-Resolution Imaging by Exploiting the Spatial Continuity Information. Sensors 2019 ,19, 1920. 
 1976.  71. Skolnik. 
 Harris and D. Lynch, “Digital signal processing and digital filtering with applications,” Evolving  Technology Institute Short Course Notes, 1971–1983, pp. 366, 744–748, February 1978. 
 Like lightwaves of much higher frequency, radar waves tend to travel in straight linesor rays at speeds approximating that of light. Also, like light waves, radarwaves are subject to refraction or bending in the atmosphere. Radio-frequency energy travels at the speed of light, approximately 162,000 nauticalmiles persecond; therefore,the time requiredfor apulse totravel to the target and return to its source is a measure of the distance to thetarget. 
 However, since this particular oscillation depends  on electron velocity, which in turn depends on beam voltage, the problem is avoided by  the use of mod-anode or grid pulsing (Section 10.7). In this case, it is only necessary  to be sure not to let the modulator begin pulsing the beam current during turn-on of the  high-voltage power supply until the voltage is safely above the oscillation range, which  is typically somewhere between 60 and 80% of full  operating voltage. A modification of the helix slow-wave structure is the ring-bar circuit, which can be  used if the peak power is less than 100 to 200 kW. 
 The computational aspects to obtain good-quality focused images are also important: recently some studies about efﬁciency have been presented [ 22] exploiting the multicore-based architectures of modern processors. Also, this aspect needs further research, as the proposed approach pays the cost of no information available for the SAR sensor with an increase of computational complexity. Also, the possibility of blind focusing SAR raw data, here addressed only in the presence of a point scatterer (e.g., a corner reﬂector or a transponder), in the general case of SAR strip map data-focusing represents the ﬁeld of application for future work. 
 However, the errors of the estimation results of ˆedr2based on the IMAM method and the EMAM 61. Sensors 2019 ,19, 213 method are relatively large. The reason is that the phase error caused by this term is very small and has little effect on the image focus based on the speciﬁc geometry in Figure 5. 
 R. Schlolter, “Digital realtime SAR processor for C & X band applications,” in IGARSS 1986 ,  Zurich, vol. 3, p. 
 82. J. Katzman, Defence Industry Daily , http://www.defenseindustrydaily.com/2005/12/elec-   tricks-turning-aesa-radars-into-broadband-comlinks/index.php. 
 The echo signal from an unambiguous  rarige target will appear at the same place on the A-scope on each sweep no matter whether the  prf is modulated or not. However, echoes from multiple-time-around targets will be spread  over a finite range as shown in Fig. 2.26~. 
 The proposed algorithm, developed in MATLAB, is distributed under the Noncommercial—Share Alike 4.0—International Creative Common license by the authors. Author Contributions: Conceptualization, C.G.; Methodology, C.G.; Software, C.G. and T.D.; Validation, C.G. 
 306-310 paraboloid. 236 Fences.radar.175.497498 Ferrimagnetic phaseshifters, 291-297 Ferritelimiter.264 Ferrite pl~seshiftas. 291-297 Ferroelectric phaseshifter.297 Field-intensity pattern. 
 The higher the  number oft he harmonic, the higher will be the order of the Bessel function and the less will be the  amount of rnicrophonism-leakage feedthrough. This results from the property that J n(x) be­ haves as x" for small x. Although higher-order Bessel functions may reduce the zero-range  response, they may also reduce the response at the desired target range if the target happens to  fall at or near a range corresponding to a zero of the Bessel function. 
 15  Radar Range Equation (Example given)  ................................ ................................ ............................... 
 Howard Consultant to ITT Industries, Inc. (CHAPTER 9) R. Jeffrey Keeler National Center for Atmospheric Research (CHAPTER 19) Eugene F. 
 TENT WITH THE TRANSMITTED PULSE LENGTH  IS APPLIED WITHIN THE )& AMPLIFIER 4HE OUTPUT FROM THE LOG AMPLIFIER ENTERS A DIODE 
 The raised portion of the  Parasitic  reflector J  (a (61 (c)  Figure 7.9 Examples of the placement of the feeds in parabolic reflectors. (a) Rear feed using half-wave  dipole; (b) rear feed using horn; (c) front feed using horn.  238INTRODUCTION TORADAR SYSTEMS radiated towardtheedgeofthereflector shouldusuallybeaboutone-tenth themaximum intensity. 
 19.Wright,J.W.:ANewModelforSeaClutter,IEEETrans.,vol.AP-16,pp.217-223, March,1968. 20.Guinard, N.W.,andJ.C.Daley:AnExperimental StudyofaSeaClutterModel,Proc.IEEE,vol.58, pp.543-550, April,1970. 21.Croney, J.:CivilMarineRadar,chap.31of"RadarHandbook," M.I.Skolnik (ed.),McGraw-Hili BookCompany, NewYork,1970. 
 If  the target is an aircraft, its position can .then be converted into cartesian coordinates for  smoothing and extrapolation of its trajectory. A constant-velocity target flying a straight line,  nonra<lial course would have radial acceleration in the spherical coordinates of the radar,  which is av~ided with cartesian coordinates.  Figure 8.3 I. 
 COVERED HENCE ITS SURFACE IS  NOT OBSERVABLE BY OPTICAL MEANS   ITS MASS AND SIZE ARE SIMILAR TO THOSE OF %ARTH  AND SPECTRAL OBSERVATIONS HAVE SHOWN THAT ITS ATMOSPHERE IS  ^ #/   SUGGESTING THAT A  GREENHOUSE EFFECT COULD HAVE OVERWHELMED WHAT MIGHT HAVE BEEN A MORE HOSPITABLE PLANET ! POPULAR THEME FOR PLANETARY EXPLORATION BY RADAR IS THE SEARCH FOR EVIDENCE OF WATER ESPECIALLY WATER 
 OFF BETWEEN GEOMETRIC AND RADIOMETRIC RESOLUTION MUST BE CONSIDERED WHEN CHOOSING THE NUMBER OF LOOKS FOR PROCESSING /NE 
 /Ê / 
 The synthetic aperture radar may be considered as a vector summa­ tion of synthetic-array elements (which is the model generally taken in this section), or it may  be considered in terms of doppler filtering. In fact, it was originally conceived by Carl Wiley of  Goodyear Aircraft Corporation in 1951 as a doppler-filtering process rather than as a syn­ thetic antenna. The two models are sometimes used interchangeably, depending upon which  describes more clearly a particular effect. 
 NORMAL BEHAVIOR FOR THE LARGER CROSS SECTIONS &ROM A DETAILED STATISTICAL ANALYSIS OF THE .2, &2 DATA  6ALENZUELA AND ,AING  CONCLUDED THAT  FOR THIS DATA AT LEAST  THE  DISTRIBUTIONS OF SEA CLUTTER CROSS SECTIONS WERE INTERMEDIATE BETWEEN THE 2AYLEIGH AND LOG 
 MM     '(Z OR + A BAND  REGION WITH THE USUAL MICROWAVE 
 Geosat was a U.S. Navy military satellite whose primary mission was  to map the Earth’s marine geoid to then-unprecedented accuracy, for which a non- repeat orbit was required. Since its public release in 1995, the data set from the first   18-month geodetic mission has become the backbone of the global bathymetric  chart that is the industry standard.72,73  Geosat’s secondary mission was to  observe dynamic mesoscale oceano - graphic phenomena, for which it was  maneuvered into an exact repeat orbit  (period 17.05 days).74 Geosat’s geo - detic mission and exact-repeat mis - sion are known as GM and ERM,  respectively. 
 575-584, Septemher, 1976.  53. Lamb, J. 
 SCATTERING MODELS )N &IGURE   THE OVERALL SCALE OF WEDGE SCATTERING AS CALCULATED BY THE '4$ WAS ADJUSTED TO LOCATE THE CLUSTER OF CROSS SECTIONS AT THE LEVEL OF THE EXPERIMENTAL VALUES 7EDGES APPEAR TO MODEL THE QUALITATIVE BEHAVIOR WITH BOTH POLARIZATIONS FAIRLY WELL AT THE LOWER GRAZING ANGLES &IGURE  ALSO INCLUDES TWO ADDITIONAL SIMPLE SCATTERING MODELS FOR COMPARISON  ,AMBERTS LAW  MENTIONED IN CONNECTION WITH &IGURE  A B  EXPRESSES THE CROSS SEC 
 Coleman, “A direction-sensitive model of atmospheric noise and its application to the  analysis of HF receiving antennas,” Radio Science , vol. 37, pp. 3.1–3.10, 2002. 
 The basic reason for poor tracking at low angle results from the fact that the conventional  tracking radar with a two-horn feed in elevation (or its equivalent for a conical-scan tracker)  provides unambiguous information for only one target. At low elevation angles two" targets"  are present. the real one and its. 
 28 INTRODUCTION TO RADAR SYSTEMS  0.9999  0.9995  0.999  0.998  0.995  0.99  0.98  C 0.95 0  +-u w +-0.90 w  "Cl  '+-0  >. 0.80 .t:  :0  0 .0 0.70 0  L a.. 0.60  0.50  0.40  0.30  0.20  0.10  0.05  4 6 ,.,., .. 
 PATTERN OUTPUTS  )NDEPENDENT CONTROL OF THE TWO  AMPLITUDE DISTRIBUTIONS IS POSSIBLE &OR EFFICIENT OPERATION  THE TWO FEED LINES REQUIRE DISTRIBUTIONS THAT ARE  ORTHOGONAL  THAT IS  THAT GIVE RISE TO PATTERNS WHERE THE PEAK VALUE  OF ONE COINCIDES WITH A NULL FROM THE OTHER AND APERTURE DISTRIBUTIONS ARE RESPECTIVELY EVEN AND ODD ! VERY WIDEBAND SERIES FEED WITH EQUAL PATH LENGTHS IS SHOWN IN &IGURE  D  )F THE BANDWIDTH IS ALREADY RESTRICTED BY PHASE SCANNING  THEN  VERY LITTLE ADVAN 
 11.20 Normalized scattering width of an infinite, per- fectly conducting cylinder for E polarization (incident electric field parallel to the cylinder axis). The normalization is with respect to the geometric optics return from the cylinder. ka FIG. 
 252 I~I KODUCTION TO KADAK SYSI'EMS  gsciiter ~IIWII A/2. Tlie direction of tile rays is [lot affccted by the refractive indcx, and Sncll's law  does not apply. Focusing action is obtained by constraining the waves to pass bet wren thc  plates in such a manner that the path length can be increased above that in free space. 
 signal or echo amplitude. Conventional AGC with a control voltage is band- limited by filters, and the gain is essentially constant during the pulse repetition interval. Also, the AGC of the sum channel normalizes the sum echo pulse am- plitude to similarly maintain a stable range-tracking servo loop. 
 A collapsing loss also results if the outputs of two (or more) radar receivers are  cornbilled and only one contains signal while the other contains noise.  Tlie mathematical derivation of the collapsing loss, assuming a square-law detector, may  be carried out as suggested by Marcumlo who has shown that the integration of nt noise  pulses. along wit11 11 signal-plus-noise pulses with signal-to-noise ratio per pulse (SIN), , is  equikalent to the integration of ~n + 11 signal-to-noise pulses each with signal-to-noise ratio  t~(S/N),/(nr + 11). 
 10, pp.891-894, 50. R. F. 
 Skolnik (ed.), McGraw-Hill Book  Co., New York, 1970.  9. Shreve, J. 
 DELAY  SYSTEM WOULD NOT HAVE THE SECOND DELAY LINE AND SUBTRACTOR 4HE NORMALLY REQUIRED  CIRCUITRY FOR MAINTAINING COHERENCE  GAIN AND PHASE BALANCE  AND TIMING IS NOT SHOWN  4HE SPEED CONTROL  6X IS BIPOLAR AND MUST BE CAPABLE OF REVERSING THE SIGN OF THE  $P    SIGNAL IN EACH CHANNEL WHEN THE ANTENNA POINTING ANGLE CHANGES FROM THE PORT TO THE STARBOARD SIDE OF THE AIRCRAFT &)'52%   -4) IMPROVEMENT FACTOR FOR $0#! COMPENSATION AS A  FUNCTION OF THE FRACTION OF THE HORIZONTAL PHASE CENTER SEPARATION  7 THAT  THE HORIZONTAL ANTENNA APERTURE IS DISPLACED PER INTERPULSE PERIOD   6X4P7  7   A  WHERE A IS THE HORIZONTAL APERTURE LENGTH.   !)2"/2.% -4)  Î°£Î 4HE HYBRID AMPLIFIER SHOWN HAS TWO INPUT TERMINALS THAT RECEIVE  3P   AND J$P    AND AMPLIFY THE  $P   CHANNEL BY  K6X RELATIVE TO THE  3P   CHANNEL 4HE OUTPUT TER 
 Pn·se11t a11d f11t11re. London, Oct. 23-25, 1973, pp. 
  
 POWER DEPENDENCE ON  GRAZING ANGLE  !N ALTERNATIVE EXPLANATION FOR THIS BEHAVIOR  APPLICABLE AT THE HIGHER  MICROWAVE FREQUENCIES  HAS BEEN SUGGESTED BASED ON A  THRESHOLD 
 Their mathematical expressions can directly describe the rheological deformation, and are applicable to the simulation of the initial or stable rheological deformation of rock and soil material [ 29,30]. However, theoretical models for time-series displacement that consider rheological parameters have been rarely mentioned in previous InSAR deformation studies. Based on the background discussed above, we propose a time-series deformation model based on rheological theory. 
 Frush: Evaluation of an Alternating PRF Method for Extending the Range of Unambiguous Doppler Velocity, Preprints, 22d Conf. Radar MeteoroL, pp. 523-527, American Me- teorological Society, Boston, 1984. 
 CLUTTER RATIO IMPROVEMENT  )3#2  FOR GAUSSIAN 
 Bit inversion occurs at intervals of a quar- ter pulse width for the second doppler channel, an eighth pulse width for the third doppler channel, etc. Negative doppler frequency channels are handled in the same manner as for positive doppler frequency channels, but bits that were in- verted in the corresponding positive channel are not inverted in the negative channel, and bits that were not inverted in the positive channel are inverted in the negative channel. No bit inversion occurs in the zero doppler channel. 
 In devising  computation algorithms and computer hardware, advantage can be taken of the fact that the  phase shill t/Jm" required at the 11111th element of a rectangular-spaced array can be separated by  row and column since tJ,m" = mt/Jr+ 111/Jx, where 111, 11 are integers corresponding to the 111th row  and 11th column, t/1 }" is the phase dilTerence needed between adjacent rows to steer the beam in  elevation. and t/1 x is the phase difference between adjacent columns needed to steer in azimuth:  This is sometimes called row/column steering. Baugh 121 describes a "non-time-critical"  row/column beam-steering computer that represents a minimum equipment approach that  takes from 10 lo 20 ms to generate the phase-shifter commands. 
  
 In these systems, analog pulse compression is performed at an IF, followed by the  ADC in the processing chain. Because pulse compression increases the SNR of  the signal, performing it before sampling increases the dynamic range requirement  of the ADC. In a digital pulse compression system, the ADC precedes the pulse  compressor and only has to accommodate the precompression dynamic range of  the signal, which can be a significantly lower requirement. 
 '---,----' Fi~url'3.13Blockdiagram ofFM-CW radarusingsideband superheterodyne receiver. .til"Thefilterselectsthelowersideband fo(t)-fiFandrejectsthecarrierandtheupper sidehand. Thesidehand thatispassedbythefilterismodulated inthesamefashionasthe transmitted signal.Thesideband filtermusthavesufficient bandwidth topassthemodulation, butnotthecarrierorothersideband. 
 This separation into spectral  lines allows for discrimination of doppler shifts. Doppler radars using pulsed transmissions are more complex than CW radars, but  they offer significant advantages. Most important is the time gating of the receiver. 
 MISSION CAPABILITY  WHICH INCLUDES BOTH ANTInAIR WARFARE !!7  AND  BALLISTIC MISSILE DEFENSE "-$  4HE "-$ REQUIREMENT TO DISCRIMINATE SMALL RADAR CROSS SECTION 2#3  RE 
 GRAPHIC SURVEYING FUNCTION  THE SYSTEM REQUIREMENT IS LESS DEMANDING 4HE PLAN RESOLUTION IS DEFINED BY THE CHARACTERISTICS OF THE ANTENNA AND THE SIG 
 (21.24) is used, one obtains X = 24> J— - —I e-**™ ~ 2^ (21.25)**L C CJ Examination of Eq. (21.25) shows that if <|>^, the autocorrelation function for g, is the same function for each member of the sequence of transmissions, then this element can be factored out and written outside the summation term of Eq. (21.25). 
 MONOSTATIC1UASI 
 The waveform autocorrelation function and  ambiguity function for an LFM waveform are given by   χ τ τ ατ τu d d f T f T T ( , ) [ | / |] ( ) ( | / |) = − − − 1 1 sinc[ ]reect( )τπ τ/2T ej fd −  (8.7)  Ψu d d f T f T T ( , ) [ | / |] [( ) ( | / |) τ τ ατ τ = − − − 1 12 2sinc ] ] /rect( )τ2T (8.8) where the sinc function is defined as  sinc( x) = sin(px)/(px)  The matched filter time response for a target with doppler shift  fd is obtained by the  substitution τ = –t in the autocorrelation function:  y t t f t T f t T tu d d ( ) ( , ) [ | / |] ( ) ( | = − = − + − χ α 1 1 sinc[ / / |) /T t T ej ftd ] rect( )2π (8.9) LFM Range-doppler Coupling.  The LFM waveform exhibits range-doppler cou - pling which causes the peak of the compressed pulse to shift in time by an amount  proportional to the doppler frequency. The peak occurs earlier in time at t = –fdT/B for  a positive LFM slope, compared to peak response for a stationary target. 
 Different  radar functions put a greater emphasis on one or the other of these parameters. For  example, imaging radars put a premium on wide bandwidth, whereas pulse doppler  radars require high dynamic range. Because radars are often required to operate in a  variety of modes with differing bandwidth and dynamic range requirements, it is not  uncommon to use different types of A/D converter, sampling at different rates for these  different modes. 
 Thesampling rateoftheAIDISdetermined bytheradarsignalbandwidth, andthenumherof bitsissetbythedynamic rangedesired. Motioncompensation forazimuth andrangeslip (rangewalk)canbeapplied, aswellasphasecorrections forfocusing. Semicond uctordevices areusedformemory andarithmetic. 
 FACE VALUE  SEEMS TO BE APPROPRIATE IN  STRATIFORM  RAINFALL  WHICH IS RAIN HAVING A  WIDESPREAD AND CONTINUOUS NATURE 3UCH WIDESPREAD RAINFALL IS USUALLY TRIGGERED BY $ROP $IAMETER $  CM0RECIPITATION 2ATE 2  MMH         0ERCENTAGE OF A 'IVEN 6OLUME #ONTAINING $ROPS OF $IAMETER $                                                                                                                                                                                                                                                                                                                                                  4!",%  $ROP 3IZE $ISTRIBUTIONS AT $IFFERENT 0RECIPITATION 2ATES 4!",%  !TTENUATION IN $ECIBELS PER +ILOMETER FOR $IFFERENT 2ATES OF 2AIN 0RECIPITATION AT A  4EMPERATURE OF n# 5SING THE $ROP 
 ¯ ¯          2ADAR  METEOROLOGISTS SOMETIMES REFER TO  SV AS THE SPECTRUM VARIANCE BECAUSE OF  ITS COMPUTATIONAL EQUIVALENCE TO THE VARIANCE OF A CONTINUOUSLY DISTRIBUTED RANDOM  VARIABLE )N SHORT   3V  IS ANALOGOUS TO A PROBABILITY DENSITY FUNCTION FOR  V SINCE IT IS  ACTUALLY A REFLECTIVITY WEIGHTED DISTRIBUTION OF PARTICLE VELOCITIES WITHIN THE SCATTERING VOLUME 4HE TERM  SPECTRUM WIDTH WILL BE USED TO REFER TO  R V )T IS CLEAR  THEREFORE  THAT  THE DOPPLER SPECTRUM CONTAINS THE INFORMATION NECESSARY TO MEASURE METEOROLOGICALLY IMPORTANT SIGNAL PARAMETERS 4HESE FIRST THREE MOMENTS ARE USUALLY REFERRED TO AS  BASE  DATA AND OFTEN LABELED :  6  AND 7 WITH THE APPROPRIATE CONVERSIONS AND UNITS )N THE MOST GENERAL CASE  QUADRATURE PHASE DETECTION IS USED TO OBTAIN THE REAL AND  IMAGINARY PARTS OF THE COMPLEX SIGNAL 4HESE ARE USUALLY DIGITIZED IN A LARGE NUMBER OF RANGE GATES  y  AT THE RADARS PULSE REPETITION FREQUENCY 4HE RESULTANT COMPLEX  TIME SERIES IN EACH GATE CAN THEN BE PROCESSED BY USING A FAST &OURIER TRANSFORM &&4  TO OBTAIN AN ESTIMATE OF THE DOPPLER POWER SPECTRUM  FROM WHICH THE ECHO POWER   MEAN VELOCITY  AND SPECTRUM WIDTH CAN BE OBTAINED &)'52%     'AUSSIAN MODEL OF THE MEAN DOPPLER POWER  SPECTRUM 4HE THREE SPECTRAL MOMENTS RECEIVED POWER   RADIAL VELOCITY  AND SPECTRUM WIDTH  CAN BE ESTIMATED FROM THE SPECTRUM AND ARE DIRECTLY RELATED TO THE METEOROLOGICAL VARIABLES OF INTEREST . 
 on Audio and  Electroacoustics , vol. AU-20, no. 5, pp. 
 We shall not be concerned about the problem of amplification,  although it is an important aspect of receiver design. Instead, we shall be more interested in the  effect of the detector on the desired signal and the noise.  One form of detector is the envelope detector, which recognizes the presence of the signal  on the basis of the amplitude of the carrier envelope. 
       u !DAPTATION OF THE DETECTION THRESHOLD  &OR A GIVEN DETECTION THRESHOLD  A  IN D"   THE  PROBABILITY OF FALSE ALARM TURNS OUT TO BE   0 '2KJFA STC 
 SHAPED REFLECTOR  FORMING A CIRCULAR APERTU RE  FED BY A HORN AT  A CENTRAL FOCAL POINT 4HIS SIMPLE REFLECTOR CONFIGURATION HAS A SURFACE SHAPE DEFINED BY THE EQUATION   ZXY FF 
 16.26  16.9 Limitation of Improvement Factor Due to Pulse  Envelope Shift  ........................................................  16.28  16.10 Effect of Multiple Spectra  ........................................  16.29  16.11 Detection of Ground Mo ving Target s  ...................... 
 BASED RADAR APPLICATIONS  INCLUDING WEATHER SENSINGMONITORING .%82!$   AND PLANETARY 3!2 MAPPING MISSIONS LUNAR AND -ARS  3IGNIFICA NT FEA 
 Markers canbeprovided either byplacing asurface containing themarks asnearly aspossible inoptical superposition with the display, orby modulating the electron beam insuch away that the marks appear as part ofthedisplay itself. Indices orcharts ruled onatransparency over thetube face arethe simplest ofalltoprovide, but their useresults inerrors due todisplay inaccuracies, toparallax, and tofaulty interpolation. Furthermore, if the origin ofthe display istobemoved, itisnecessary toprovide a corresponding motion ofthereference system, which isusually cumber- some, orifonly afew positions areinvolved, tofurnish multiple sets of marks insuch away that noconfusion results. 
 Ward and W. W. Shrader34 © IEEE 1968 ) ch02.indd   62 12/20/07   1:45:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 84. Hanson, V. G., and H. 
 METRIES ASSOCIATED WITH WINDS  CURRENTS  REFRACTION  ISOLATED SWELL COMPONENTS  ETC  . 
 ALARM RATE SINCE TARGETS CAN EASILY BE CON 
 592-597, August 1954. 12. Aushe*man, D. 
 %   
 In general, the higher  values of k occur in the southern part of the country. Burrows and Attwood5 state that k lies  between ! and ! in arctic climates.  The use of an effective earth's radius implies that dn/dh is constant with height, or in other  words, that n decreases linearly with height. 
 Thus allthat is.required isalimiting i-famplifier toremove theamplitude variations, followed byaphase-sensitive detector toconvert the phase variations into uniform amplitude variations. To obtain the maximum sensitivity yfortargets moving inthe clutter itis necessary that thephase-sensitive detector should have alinear character- istic—that is,the output amplitude variation should beproportional to the input phase variation. This can beachieved byusing abalanced detector formixing the reference signal with the output ofthe limiting i-famplifier. 
 28, October, 1975.  135. Hsiao, J. 
 (Yi Liu) and Y.C.; Visualization, Y.L. (Yi Liu); Supervision, Y.L. (Yaolin Liu); Funding Acquisition, Y.L. 
 It is the purpose of this subsection to derive expressions for signal-to-noise (SIN) ratio for radars in which pulse compression and synthetic antenna techniques are used. The signal-to-noise ratio for a radar system as a result of the reception of a single pulse is given by the well-known radar equation S _ PtGtArv K ~ (4TT)2^J0BFn (2L51) In a pulse compression radar, signal-to-noise improvement occurs in the ratio of the uncompressed pulse length T, to compressed pulse length T0. In a radar that achieves its azimuth resolution by the generation of a synthetic antenna, there is an additional signal-to-noise improvement factor due to the in- tegration of a number of pulses. 
 1.2 expressed the maximum radar range  R,,, in terms of radar and target parameters:  where P, = transmitted power, watts  G = antenna gain  A, = antenna emective aperture, m2  a = radar cross section, m2  Smin = minimum detectable signal, watts  All the parameters are to some extent under the control of the radar designer, except for the  target cross section a. The radar equation states that if long ranges are desired, the transmitted  power must be large, the radiated energy must be concentrated into a narrow beam (high  transmitting antenna gain), the received echo energy must be collected with a large antenna  aperture (also synonymous with high gain), and the receiver must be sensitive to weak signals.  In practice, however, the simple radar equation does not predict the range performance of  actual radar equipments to a satisfactory degree of accuracy. 
 ÓÎ°£n  2!$!2 (!.$"//+  OR TARGET AZIMUTH AND ELEVATION MEASUREMENTS CAN BE CONVERTED TO  P2 "EAM 
 This is the type of scattering alluded to in connection with the high graz - ing angle returns discussed in Section 15.3; the tendency of s  0 to level off for grazing  angles close to 90° (see Figures 15.3 and 15.4) may be ascribed to this mechanism. From what has been said thus far, it can be seen that strict analytical solutions via  the GBVP approach appear to run into dead ends: intractable formal expressions in the  form of Eq. 15.12, small-amplitude approximations in the form of Eq. 
 68-89, March, 1954. ·  10. Siebert, W. 
 (Amplitude modulation is  also possible, but is seldom used.) The received signal is processed in a matched filter that  420INTRODUCTION TORADAR SYSTEMS Acontinuous waveform (asinglepulse)produces anambiguity diagram withasingle peak.Adiscontinuous waveform canresultinpeaksintheambiguity diagram atothervalues ofTR,fd'Thepulsetrain(Fig.11.11orII.J3b)isanexample. Thepresence ofadditional spikescanleadtoambiguity inthemeasurement oftargetparameters. Anambiguous measure­ mentisoneinwhichthereismorethanonechoiceavailable forthecorrect valueofa parameter, butonlyonechoiceisappropriate. 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 For range tracking, it is necessary to relate range noise to the target reflectivity distri - bution along the range coordinate. In general, the long-time-average value of the rms  range error may be closely estimated by taking 0.8 times the radius-of-gyration of the  distribution of the reflecting areas in the range dimension based on many measure - ments of small, large, and multiple aircraft. 
 .J Scattering fromrain.Equation (13.18),whichappliesforRayleigh scattering, maybeusedasa basisformeasuring withradarthesumofthesixthpoweroftheraindrop diameters inaunit volume. TheRayleigh approximation isgenerally applicable belowCband(5cmwavelength) and,exceptfortheheaviest rains,isagoodapproximation atXband(3cm).Rayleigh scattering usuallydoesnotapplyaboveXband.Another complication atfrequencies aboveX bandisthattheattenuation duetoprecipitation precludes themakingofquantitative measure­ mentsconveniently. Thesumofthesixthpowerofthediameters perunitvolumeinEq.(13.18)iscalledZ,the radarreflectivity factor,or (13.19) InthisformZhaslittlesignificance forpractical application. 
   2OME !IR  $EVELOPMENT #ENTER  "EDFORD  -!  !UGUST   % "ROOKNER  h! REVIEW OF ARRAY RADARS v -ICROWAVE *  VOL   PP n  /CTOBER  % "ROOKNER  h2ADAR OF THE S AND BEYOND v  )%%% %LECTRO   -AY &)'52%    !.309 
 Against a slowly moving source of clutter (e.g., birds), the probability of detection  may increase as the clutter source crosses the boundary between two clutter map cells.  To prevent this, a spreading technique can be used, through which each clutter map  cell will be updated—not only with radar returns falling within its boundaries, but also  ch02.indd   85 12/20/07   1:47:00 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 BLOCKING SWITCHED NETWORK )NTERNAL  AND EXTERNAL BUSSES C ONNECT THE INDIVIDUAL  PROCESSING ARRAYS TO EACH OTHER AS WELL AS TO THE OTHER SUITES  SENSORS  CONTROLS  AND DISPLAYS 5SUALLY  THERE ARE BOTH PARALLEL ELECTRICAL SIGNAL BUSSES AS WELL AS SERIAL FIBER  OPTIC BUSSES DEPENDING ON SPEED AND TOTAL LENGTH IN THE AIRCRAFT  4HE SIGNAL AND DATA   PROCESSOR COMPLEX CONTAINS MULTIPLE PROCESSOR AND MEMORY ENTITIES  WHICH MIGHT BE &)'52%  -&!2 PROCESSING ADAPTED    . 
 48. Kelleher, K. S., and C. 
 FREQUENCY (&  RADARS USUALLY OPERATE IN THE FREQUENCY RANGE  BETWEEN ABOUT  AND  -(Z  CORRESPONDING TO WAVELENGTHS BETWEE N  AND  M   RESPECTIVELY 3INCE THE OPERATION OF SUCH RADARS TAKES PLACE EITHER BY THE GROUND WAVE OR OVER IONOSPHERIC SKY 
 Under the supervision of L.C., C.W. performed the analysis and wrote the manuscript. Y.W. 
 Knight, and S. Spinella: Electron-Bombarded Semiconductor Devices, "Advances in  Electronics and Electron Physics, vol. 44," Academic Press, Inc., New York, 1977. 
 In each of the above expressions, Z is in mm6/m3 and R is in mm/h. In Eq. (23.48), R is the precipi- tation rate of the melted snow. 
 THE RADAR EQUATION 45  (PORT)  (W  Figure 2.21 Azimuth variation of the radar cross-section of a large Naval Auxiliary Ship at (a) S band  (2800 MH7) and (h) S band (9225 MHz), both with horizontal polarization.  (PORT!THERADAR EQUATION 45 led (a) (BOW) d lee! (b) Figure2.21Azimuth v<lriation oftheradarcross-section ofalargeNavalAuxiliary Shipat(a)Sband (2800MHz)and(h)Xband(9225MHz).bothwithhorizontal polarization.. 46 INTRODUCTION TO RADAR SYSTEMS  The cross-section data presented in this section lead to tl-tt: concliision that it woiild not be  appropriate simply to select a single value and expect it to have meaning in the compi~tation of  the radar equation without further qualification. 
 If the radar utilizes more than one doppler filter, the effect of stalo instability should be calculated for each individually. If an individual filter's doppler re- sponse is unsymmetrical, residues from positive and negative doppler bands must be computed separately and added in power. It should be noted that many textbooks analyze only a simple two-pulse MTI, and the resulting equations for the limitation on MTI improvement factor cannot be employed for more sophisticated doppler filters. 
 20.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 HF Over-the-Horizon Radar James M. Headrick Naval Research Laboratory (retired) Stuart J. 
 “Maritime navigation and radiocommunication equipment and systems—Shipborne radar,” IEC  62388, International Electrotechnical Commission, Geneva, 2007. 12. “Maritime navigation and radiocommunication equipment and systems—General requirements,”  IEC 60945, International Electrotechnical Commission, Geneva, 2002. 
 Skolnik, M. I.: Sea Echo, chap. 26 of "Radar Handbook," M. 
 Then, the techniques are introduced according to their use in the vari - ous sections of radar, namely, antenna, transmitter, receiver, and signal processing.  A key role is also played by those ECCM techniques that cannot be classified as  electronic, such as human factors, methods of radar operation, and radar deployment  tactics (Section 24.10). The ensuing Section 24.11 shows the application of the aforementioned techniques  to the most common radar families, namely, surveillance, tracking, multifunctional,  phased-array, imaging, and over-the-horizon radars. 
 In order to improve the efﬁciency in practical applications, the intervals between windows can be appropriately increased, and the offset of each azimuth frequency can be obtained by the curve ﬁtting. Then, the spatially-variant ˆedr(fdc)and ˆe3rd(fdc)can be obtained based on the estimated Δˆfd,ij(fdc). After obtaining ˆedr(fdc)and ˆe3rd(fdc), the operation of the curve ﬁtting is performed. 
 In order to avoid fuzzy height, the interferometric phase difference shall meet the requirement of Δϕ≤2π, so that the baseline length meet the requirement of d≤λR0 2H, wherein λ represents transmitting frequency, R0represents distance from the receiving/transmitting antenna to the target, and δy=c 2Brepresents maximum height of the target. (2) Sampling principle Range resolution in ISAR imaging is δy=c 2B, and azimuth resolution is δx=λ 2θ, wherein B represents signal bandwidth and θrepresents azimuth accumulation angle. In actual imaging, the 172. 
 When a target of interest had a range of less than 30 miles, the selection of the 30 mile range scale was done in two stages [ 8]. First the 100/30 scale was selected, showing targets with a 30 mile radius PPI display but still using the 0 –100 miles marker scale. In this way as the display scale was changed both target and range marker remained associated on the screen, allowing the targetto be identi ﬁed. 
 2.The -ASG, avery similar equipment made fortheNavy byanother manufacturer, which offers only PPI display. 3.The AN/.4 PS-l5, a3-cm radar with optional sector scan and with PPI display, designed foroverland bombing butused forseasearch w-hen its“cosecant-squared” antenna (Sec. 2.5) providing high- altitude coverage isreplaced byone designed forabout 5000 ft, theoptimum altitude forseasearch, 4.Aseries ofN’avy equipments operating at3cmand designed for theprimary purpose ofhoming. 
 B. Kostinski, “Feasibility of data whitening to improve performance of  weather radar,”  J. Appl. 
 BAND RADARS v  3EA 4ECHNOLOGY   !UGUST   4 + "HATTACHARYA ET AL  h#ROSS 
 OGY AND THE USE OF VOLTAGE BECAME EXPERIMENTALLY MORE USEFUL 4HE MOST BASIC MODEL FOR ASSESSMENT OF VOLTAGE SIGNAL LEVEL IS DERIVED FROM THE RADAR RANGE EQUA 
 Trunk Naval Research Laboratory 8.1 INTRODUCTION Since the invention of radar, radar operators have detected and tracked targets by using visual inputs from a variety of displays. Although operators can perform these tasks very accurately, they are easily saturated and quickly become fa- tigued. Various studies have shown that operators can manually track only a few targets. 
 The backscatter cross section of a particle in the Rayleigh region, as  shown by Eq. (13.17) varies as the fourth power of the frequency. A radar operating at L hand  (1.3 GHz), for example, might experience about 34 dB less precipitation cltlttct(han a radar at  X band (9 GHz). 
 Traveling Wave Tube . As mentioned, the TWT and the klystron can have compa - rable bandwidths when the tube produces high power. The performance of a TWT is  similar to that of a wideband klystron, except that it might not be as stable as the klystron  and have slightly less gain. 
 such networks would be operated so as to achieve the maximum output  signal-to-noise ratio.  Noise figure of networks in cascade. Consider two networks in cascade, each with the same  noise bandwidth B" but with dilTerent noise figures and available gain (Fig. 
 75. Block, A., R. C. 
 Although lower peak-  sidelobes can be obtained in this manner, the far-out sidelobes are generally considerably  greater than if the same illumination function were used to establish an amplitude taper with  an equally spaced array.  The unequally spaced array has seen only limited application, primarily because its  advantages do not usually outweigh its disadvantages. The reduction in gain and the increases  in sidelobes that are a consequence of thinning the elements are usually not desirable in most  radar applications. 
 !EX   HTTPSCIESAINTSCIENCE 
 COUPLED AMPLIFIER PAIR AND  B  SPLIT 
 The dynamic range is greater since digital MTI processors  do not experience the spurious responses which limit signals in acoustic delay lines to about 35  to 40 dB above minimum detectable signal level.25 (A major restriction on dynamic range in  a digital MTI is that imposed by the A/D converter.) In an analog delay-line canceler the delay  time and the pulse repetition period must be made equal. This is si~plified in a digital MTI  since the timing or the sampling of the bipolar video can be controlled readily by the timing of  the transmitted pulse. Thus, different pulse repetition periods can be used without the necessity  of switching delay lines of various lengths in and out. 
 If the  382INTRODUCTION TORADAR SYSTEMS thatcanbeemployed withphased:-arrayradar. 39,42Theradartransmits apulseor.aseriesof pulsesinaparticular direction asinanordinary radar,exceptthatthefalsealarmprobability isslightly higherthanwouldnormally beused.Ifnothreshold crossings areobtained, the antenna beammovestothenextangularposition. However, ifathreshold crossing isobserved fromanyrangecell,asecondpulseorsetofpulsesistransmitted withhigherenergy,andwith adifferent threshold. 
 ENCE OF ALL ITS TERMINATED NEIGHBORS 4HE ELEMENT WILL DELIVER POWER TO ITS NEIGHBORS  AND THIS LOSS IN POWER CORRESPONDS TO THE AVERAGE POWER LOST WHEN SCANNING !N IDEAL  ALTHOUGH NOT NECESSARILY REALIZABLE ELEMENT PATTERN  WOULD PLACE ALL THE RADIATED POWER INTO THE SCAN REGION  GIVING A PATTERN LIKE A COSINE ON A PEDESTAL AND THEREBY PROVIDING MAXIMUM ANTENNA GAIN FOR THE NUMBER OF ELEMENTS USED 4HINNED !RRAYS  4HE NUMBER OF RADIATING ELEMENTS IN AN ARRAY MAY BE REDUCED  TO A FRACTION OF THOSE NEEDED COMPLETELY TO FILL THE APERTURE WITHOUT SUFFERING SERIOUS DEGRADATION IN THE SHAPE OF THE  MAIN BEAM (OWEVER  AVERAGE SID ELOBES ARE DEGRADED  IN PROPORTION TO THE NUMBER OF ELEMENTS REMOVED 4HE ELEMENT DENSITY MAY BE THINNED SO AS TO TAPER THE AMPLITUDE DISTRIBUTION EFFECTIVELY  AND THE SPACING IS SUCH THAT NO COHERENT ADDITION CAN OCCUR TO FORM GRATING LOBES ! THINNED APERTURE  WHERE ELEMENTS HAVE BEEN REMOVED RANDOMLY FROM A REGULAR GRID   IS SHOWN IN &IGURE  4HE  GAIN IS THAT DUE TO THE ACTUAL NUMBER OF ELEMENTS  .'EP    BUT THE BEAMWIDTH IS THAT  &)'52%   A  4HINNED ARRAY WITH A  
 The majority of modern marine radars operate within a range of 400to 4000 pulses per second. If the distance to a target is to be determined by measuring the time required for one pulse to travel to the target and return as a reﬂected echo, itis necessary that this cycle be completed before the pulse immediatelyfollowing is transmitted. This is the reason why the transmitted pulses mustbe separated by relatively long nontransmitting time periods. 
 ATE A CIRCULAR FEATURE WHOSE RADIUS INCREASES WITH DEPTH ! TYPICAL EXAMPLE IS GIVEN IN &IGURE   WHICH SHOWS THE # 
 This unit was tasked with undertaking trials of new radars and developing tactics for their use.This work was very valuable and CCDU was expanded to undertake service trials of all new Coastal Command aircraft and equipment [ 1]. CCDU moved to Ballykelly in November 1941 and then in June 1942 to Tain. In September 1943 CCDU movedto RAF Angle. 
 Frediani, G. H. Knittel, and A. 
 ING NETWORKS  WHETHER THESE NETWORKS ARE HYBRID CONSTRUCTION OR --)# CONSTRUCTION !DDITIONAL LOSSES DEGRADE THE INHERENT POWER  GAIN  AND EFFICIENCY CHARACTERISTICS OF THE INTRINSIC &%4 4HE MOST APPROPRIATE AMPLIFIER DESIGN FOR A GIVEN APPLICATION REQUIRES OPTIMIZATION OF THE TRANSISTOR  AND THE VARIABLES THAT AFFECT THAT OPTIMIZATION  SUCH AS UNIT GATE LENGTH  GATE WIDTH  NUMBER OF GATE FINGERS  CELL CONSTRUCTION  IMPEDANCE MATCHING CIRCUITS  AND BIAS NETWORKS  ALL REQUIRE DETAILED ATTENTION DURING THE DESIGN OF THE AMPLIFIER %XCELLENT COMPILATIONS OF INDUSTRY PERFORMANCE HAVE BEEN PUBLISHED FOR FURTHER INSIGHT   4HESE REFERENCES OUTLINE STATE 
 Ê,,9Ê/, - // 
 Inthecase ofthescanning data, itisoften possible toprotect against transient interference (orabsence ofsignals) byexploiting electrical or mechanical inertia. Care must betaken that the inertia does not appreciably inhibit satisfactory response toscanning accelerations, a serious restriction ifsector scanning isinvolved. Asecond, and more promising, method ofapproach istotake advan- tage ofapproximate knowledge ofwhat the real signals should doby excluding completely allinformation that does not closely agree with expect ation, just astuned circuits orfilters reject signals outside their pass band. 
 Rattan. L. J.: " Radar Observation of the Atmosphere." University of Chicago Press, Chicago, 1973. 
 MOUNTED ANTENNA DICTATE THAT THE ILLUMINATION PATTERN WILL HAVE LITTLE OR NO DIRECTIVITY 0ROCESSING OVER GROUPS OF RETURNS TO REDUCE THE EFFECTIVE WIDTH OF THE BEAM CAN BE HELPFUL $OPPLER 
 A directive antenna not only provides the  transmitting gain and receiving aperture needed for detecting weak signals, but its narrow  beamwidth allows the target's direction to be determined. A typical radar might have a heam­ width of perhaps one or two degrees. The angular resolution is determined by the beam width,  but the angu]ar accuracy can be considerably better than the beamwidth. 
 The amplifier shows somewhat "linear" transfer characteristics as the drive is increased until the device begins to saturate. Eventually a point of saturated power output capability of the device is attained, and further increases in RF input drive level will actually produce a degraded power output level. At this point the device may also be thermally limited at a device junction. 
 A silicon  crystal and a tungsten wire are used as the rectifying  contacts, and with correct adjustment this gives a ‘back-  to-front’ ratio of about seven. The crystal and contact  wire are mounted up in the capsule, which forms an  . [22 HOW RADAR WORKS  integral part of the transmission line, and when the  contact is satisfactory the whole capsule is filled with  molten wax to stabilize the crystal against vibration. 
 BLOCKAGE REFLECTOR BLOCKING ITSELF  IS ANOTHER POTENTIAL LIMITING FACTOR IN SPHER 
 AIR SEARCH 4HE CHOICE BETWEEN HIGH AND MEDIUM 02& INVOLVES A NUMBER OF CONSIDERATIONS   SUCH AS TRANSMITTER DUTY CYCLE LIMIT  PULSE COMPRESSION AVAILABILITY  SIGNAL 
 Kittredge, F., E. Ornstein, and M. C. 
 Amplitude scintillation effects on SAR. IET Radar Sonar Navig. 2014 ,8, 658–666. 
 ORTHOGONALITY ON THE SCATTERING PROPERTIES OF DIHEDRAL  REFLECTORS v )%%% 4RANS  VOL !0 
 86. Mortley, W. S., and S. 
 However, when the target is in motion  relative to the radar, /4 has a value other than zero and the voltage corresponding to the  dilkrence frequency from the mixer [Eq. (4.3)] will be a function of time.  An example of the output from the mixer when the doppler frequency/;, is large compared  with the reciprocal of the pulse width is shown in Fig. 
 R. K. Moore, J. 
 Each correlator may actually consist of several correlators, one for each quantization bit of the digitized signal. Two methods of implementing the correlators are shown in Fig. 10.13. 
 It exhibits optimum performance when the pyra - mids are pointed toward the direction of the incident wave, and the pyramids should  be of the order of 3 to 6 wavelengths deep. Fire-retardant paint is usually applied to  pyramidal absorbers to satisfy safety requirements, but at high frequencies, the paint  tends to degrade the performance of the material. Nevertheless, pyramidal absorbers  of sufficient depth consistently turn in performances better than (less than) −50 dB. 
 WATER CONTENT AND IS INDEPENDENT OF THE DROP 
 Glint Reduction in the Bistatic RCS Region.  A second effect can occur in the  bistatic region. When the bistatic RCS reduction is caused by a loss or attenuation of  ch23.indd   20 12/20/07   2:21:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Zrnic, and C. L. Frush, “Review of range velocity ambiguity mitigation tech - niques,” in 29th Conf. 
 Timing signals are also supplied to  the indicator to provide the range zero. Angle information is obtained from the pointing  direction of the antenna. The most common form of cathode-ray tube display is the plan  position indicator, or PPI (Fig. 
 SUREMENT CELL  AND  3.2 IS THE SIGNAL 
 10.45a; Fig. 10.45b shows the equivalent circuit ofaprac- tical transformer (all values referred tothe secondary orhigh-voltage Low-voltage High-voltage end end :~~[, ;q-R[L (a) (b) FIG. 10.45.—Puke transformer circuit diagram. 
 'l'lic pliasc-phase array is what is generally implied when the term  elrc~~r~o~tic~c~llr .\reclrctl phctseel clr.rirJ1 is used.  The phased array antenna has seen application in radar for such purposes as aircraft  sirrveillatice fro111 on board sflip (AN/SPS-33), satellite surveillance (AN/FPS-85). ballistic  rriissile defense (PAR, MSR), air defense (AN/SPY-1 and Patriot), aircraft landing systeriis  (AN/TPN-19 and AN/TPS-32), mortar (AN/TPQ-36) and artillery (AN/TPQ-37) location. 
 If saturations do occur in a range gate during an integration period, an option in a multiple-range-gated system is simply to blank detection reports from that gate. Tb most stressing dynamic-range requirement is due to main-beam clutter when searching for a small low-flying target. Here, full sensitivity must be main- tained in the presence of the clutter to maximize the probability of detecting the target. 
 J. H .. and D. 
 12.12. The dotted portions arethe additions necessary toinclude beacon AFC. SEC. 
 14. PRIME POWER SUPPLIES FOR RADAR. 555 .41RCRAFT SYSTEMS 141 14.2 143 14.4 145 14.6 14.7 14.8 14.9Choice ofFrequency. 
 Feedback can be used to narrow the rejection  notch without much degradation of I. If feedback is used to increase the improvement  factor, the single-scan probability of detection becomes worse. Figure 2.37 shows the improvement factor limitation due to scanning for cancelers  with feedback. 
 (ILL    #HAP   & .ATHANSON   2ADAR $ESIGN 0RINCIPLES  .EW 9ORK -C'RAW 
 Results of most of these measurements are summarized in Ulaby, Moore, and  Fung37 and Ulaby and Dobson.38 More complete summaries of the earlier work and  near-grazing studies are in Long22,39 and in the work of Billingsley.17 Many applica - tion summaries are also in the Manual of Remote Sensing .40,41 Readers requiring more  detailed information should consult these books . 16.2 PARAMETERS AFFECTING   GROUND RETURN Radar return depends upon a combination of system parameters and ground parameters: Radar system parameters (Eqs. 16.1 and 16. 
 ARRAY OUTPUTS  IS EQUAL SUBSEQUENTLY THE MISSING TAPER WEIGHTS ARE APPLIED DIGITALLY AT SUB 
 WAVE  METHODS 0HYSICAL /PTICS 0/  2EFLECTOR !NALYSIS  4HE 0HYSICAL /PTICS 0/  METHOD  IS COMMONLY EMPLOYED FOR THE MOST RIGOROUS REFLECTOR ANALYSIS DUE TO ITS ACCURACY )T INCORPORATES THE FIELD PROPERTIES OF THE FEED  AND MODELS THE RESULTANT FIELDS FROM THE REFLECTOR  THUS ENABLING THE COMPUTATION OF THE CROSS POLARIZATION PROPERTIES &URTHERMORE  THE METHOD IS MORE ACCURATE FOR FEEDS THAT ARE NOT AT THE FOCAL POINT AND REFLECTORS THAT ARE NOT PARABOLIC 4HERE ARE MANY GOOD REFERENCES THAT DESCRIBE THE THE 
 SEC. 9,5] CONSTRUCTION OF RADAR ANTENNAS 279 Beacon antennas areoften made upofavertical array ofradiating elements excited inphase. Bycorrect design ofsuch anantenna the pattern canbemade reasonably uniform inazimuth and atthesame time well confined totheregion ofthehorizon. 
 The natural result in this case is the so- called dawn-dusk orbit, in which the satellite—and its solar-panel-dependent power  system—avoids the shadow of the Earth almost always for almost all seasons. Certain applications are particularly well-served by exact-repeat orbits. For exam - ple, if a group of orbital trajectories falls within a small radius of each other when over  an area of interest, then radar measurements from several orbits may be compared  coherently, thus potentially sensitive at the order of a wavelength to changes in the  scene between observations. 
       XXYXY R XR XR RYR YR RZR ZR R    
 Burgers, J. Application of a Model System to Illustrate Some Points of the Statistical Theory of Free T urbulence ; Springer: Dordrecht, Netherlands, 1940. 20. 
 IDEAL FILTER RESPONSES !N INFINITE NUMBER OF TAPS WOULD BE REQUIRED TO SET THE PASSBAND GAIN TO UNITY AND THE STOPBAND GAIN TO ZERO HOWEVER  FOR MOST APPLICATIONS  SUFFICIENT PROCESSING RESOURCES ARE AVAILABLE TO REDUCE THE ERRORS TO INSIGNIFICANT LEVELS &INITE LENGTH WORDS FOR FILTER COEFFICIENTS PRODUCE NON 
 The antenna equivalent of the conventional Fourier transform is  the Blass beam-forming network illustrated by Fig. 8.26. The Blass network required N~  couplers for N inputs and N outputs, while the conventional Fourier transform also requires  NZ computations for an N-point transform. 
 R. Forrest: Principles of Independent Receivers for Use with Co-operative Radar Transmitters, Radio Electron. Eng., vol. 
 Themeasurement ofdistance relativetooneofthesitesrequires a knowledge ofboththeangleofarrivalatthereceiving siteandthedistance between transmit­ terandreceiver, aswasindicated byEq.(14.33).Anyofthemethods formeasuring rangewith amonostatic radarcanbeappliedtobistaticradar,including pulseandFM-CW modulations. Ifthedirectsignalfromthetransmitter isavailable atthereceiving site,itcanbelIsedasa reference signaltoextractthedoppler frequency shift.However, thedirectsignalcanseriously interfere withthemeasurement oftheangleofarrival,justasdoesamullipatl1 signal.To extracttheangular location ofthetarget,thedirectsignalmustbeseparated insomemanner fromthetargetsignals.Thisisnotaneasytasksincetheanglesofarrivalofthedirectand scattered signalsaregenerally closetooneanother whenthebistaticradarisarrangl:d to provide fencecoverage. BistaticRadarequation. 
 11.27 Angles of incidence and scattering for wedge geometry. guished between "uniform" and "nonuniform" induced surface currents. The uniform currents are the surface currents assumed in the theory of physical op- tics, and the nonuniform currents are associated with the edge itself (filamentary currents). 
 Puhl. no. 155. 
 REGION APPROXIMA 
 The first is to focus on one particular term  of the radar range equation, the propagation factor FP (defined in Section 26.6).  Encompassed within the propagation factor are all the effects upon propagation attrib - utable to the natural environment. These effects are energy absorption from gasses and  liquid water, diffraction, refraction, multipath interference, earth-surface dielectrics,  terrain interference, and a number of other natural environmental considerations. 
 The local oscillator isa2K25 klystron, which can betuned mechani- cally over alarge range and electrically over arestricted range ofsome 30Me/see. The electrical tuning can bedone manually, bymeans ofa remote potentiometer, orautomatically. The AFC circuit operates asfollows. 
 4IME !DAPTIVE 0ROCESSING 344 3INGLE 4ARGET 4RACKER 4O! 4IME OF !RRIVAL 43) 4ERRAIN 3CATTERED )NTERFERENCE 46 
 Burrows, and E. B. Ferrell: Ultra-Short-Wave Propagation, Proc. 
 This content has been downloaded from IOPscience. 
 RATED INTO PROBABILISTIC DATA ASSOCIATION v  * %LEC %LECTRON %NG !USTRALIA   )% !UST  AND )2%%  !UST  VOL   PP n    9 "AR 
 ARRAY ARCHITECTURE THE MAXIMUM VALUE OF THE 3).2 IS LOG  n TAPERING LOSSES  &IGURE  DEPICTS THE 3).2 FOR THE REGULAR ARRAY CONFIGURATION AND ABSENCE OF  TAPERING )T IS NOTED THAT WHEN THE JAMMER $O! IS AROUND   THE 3).2 DECREASES THIS IS BECAUSE OF THE GRATING LOBE 4HE MAXIMUM VALUE OF 3).2 IS  D"   LOG    BECAUSE THERE ARE NO TAPERING LOSSES&)'52%   3).2 VERSUS THE JAMMER $O! *$O!           
 I'- L. L L-_....l._----'- __ o10203040506070 GRAZING ANGLE (degrees) Figure13.8Boundaries ofmeasured radarreturnatXbandfromvarious landclutter. 35(Co/lrresyof1.Karz.)E22Z3CITYc==JCULTIVATED TERRAIN \::::::::::::;:;:::3ASPHALT c=JCONCRE TEVERTICAL POLARIZATION r 10'--__ .J--_-L-._~.L_L_----'--_----.L __ L.-_--'----_--.J 2030405060708090 GRAZING ANGLE (degrees)20 \0 0 -10 CD ~-20 0 b -30 -40 -50 -60 0 asoft.wetsnowcover onvegetation tendstolowerthereturnbyasmuchas6dB.40Measure­ mentsmadeoversnowfields nearThule,Greenland, showed thebackscatter tobepropor­ tionaltothesquareofthefrequency overthefrequency rangefromUHFtoXbandandat grazing anglesfrom5to20°:!? Frequency dependence. 
 19.59.  115. Miller. 
 The operational use made ofthe SCR-584 asmodified foraircraft control was basically any that required precise navigation under restricted visibility. Large aircraft could carry radio and radar navigational aids which often made itpossible forthem tocarry outsuch missions without assistance, but thefighters and fighter-bombers oftheTAC’S had neilhcr ———.——— FIG.7.17.—X-Y plotting board forSCR-584. space nor operators forsuch equipment. 
 14.16  Subcarriers  ........................................................  14.16 Amplication  ........................................................  14.18  Doppler Filter Banks  .......................................... 
 Examples of passive ECM  are chaff, decoys, and radar cross-section reduction.  One of the earliest forms of countermeasures used against radar was cJu~ft: Chaff consists  of a large number of dipole reflectors, usually in the form of metallic foil strips packaged as a  bundle. The many foil strips constituting the chaff bundle, on being released fr9m an aircraft,  are scattered by the wind and blossom to form a highly reflecting cloud. 
 Because thunderstorms contain important spatial features, such as heavy precipita - tion shafts and updraft cores, with horizontal dimensions of the order 1 to 5 km, a 1 °  beam is reasonably well matched to these atmospheric phenomena being observed out  to ranges of a few hundred km. Shorter-range airborne weather radars often employ  beamwidths of 2–3 ° as a compromise between wavelength requirements and antenna  size constraints whereas spaceborne radars may use a fraction of a degree beamwidth  to retain usable horizontal resolution at typical long ranges (250–500 km). Operational weather radars normally are capable of short and long pulse operation  in the range of 0.5 µs to about 6 µs and PRFs between 300 and 3000 Hz for long- range precipitation radars. 
 LYZE THE SYSTEM IN THE TIME DOMAIN INSTEAD 4HIS IS 3!2 4HE EQUIPMENT REMAINS THE SAMEnJUST THE EXPLANATION CHANGES #ONCEPTION WAS REPORTED IN A 'OODYEAR !IRCRAFT REPORT IN v  3UBSEQUENTLY  AS DESCRIBED IN 3ECTION  OF 3CHLEHER  $"3 CAME TO REFER TO AN  AIRBORNE SCANNING MODE IN WHICH THE ECHOES FROM THE SCANNING REAL BEAM ARE DOPPLER 
 Emerson, R. C.: Some Pulsed Doppler MTI and AMTI Techniques, Rand Corporation Kept. R-214, DDC Doc. 
 2AYLEIGH RETURNS  NOTED IN 3ECTION  HAS LED TO AN AUGMENTATION OF THE TWO 
 2.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 MTI Radar William W. 
 Hence,the cross-range resolution of the focused synthetic aperture using  Eq. (14.4) with L" = RJ/D is  D dcr = R(J, = 2 (14.6)  The resolution of the focused SAR is independent of the range and the wavelength, and  depends solely on the dimension D of the real antenna.  An example comparing the resolution of the conventional antenna and the two types of  synthetic aperture antennas is shown in Fig. 
 This is not so in radar. Both position (range or time delay) and velocity (doppler  frequency) may in theory be determined simultaneously if the pa product and/or the  E/No ratio are sufficiently large. The two uncertainty principles apply to different phenomena,  and the radar principle based on classical concepts shouldnot be confused with the physics  principle that describes quantum-mechanical effects. 
 ELEMENT SLOTTED WAVEGUIDE PHASED ARRAY WITH  D" GAIN  IS ELECTRONICALLY SCANNED OVER  on ACROSS TRACK  COVERING A SWATH   
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 Modern space-based SARs owe their large mode variety to active electronic- steered antenna arrays. 
 The two curves in Fig. 20.6« correspond to uniformly illuminated sum beams. In one case, the delta beam is formed by subtracting the upper and lower halves of a uniformly illuminated aperture. 
 LOOK  AZIMUTH RESOLUTION AVAILABLE FROM THE  -AGELLAN ANTENNA COULD  BE ABOUT  METERS 3ECTION   4HIS IS ON THE ORDER OF   TIMES SMALLER THAN THE SCI 
 -ISSILE 
 These lines ofconstant efficiency arethedotted lines looping upand totheright onthediagram. 101 1 1 o10 20 30 40 50 60 70 80 Current Inamperes—. 338 THE MAGNETRON A.VD THE PULSER [SEC. 
 HERTZ DIFFERENCE FREQUENCY ;CALLED A  K(Z PHASE SIGNAL IN THE FIGURE=x  4HERE IS A RADIO RECEIVER AND CONSEQUENTLY A  
 143-144  externally coherent, 138  filter bank. 121-125, 127  IF cancellation, 126  improvement factor:  antenna scanning. 134-136  antenna sidelobes, 145  clutter fluctuations. 
 Substituting into this  equation produces  bADDER  = 12 + CEIL[log2(103)] = 12 + CEIL[9.966] = 12 + 10 = 22  In practice, although the first adder stage must support this number of bits, lower  order bits may be pruned from the adders in successive stages, as described by  Harris.10 A CIC interpolating filter would be preceded by a FIR-filter-based interpolator.  CIC interpolators are described in detail in the referenced literature. The Discrete Fourier Transform (DFT). 
 138. Zhuk, M. S .. 
 QUENCY MODULATE THE WAVEFORM OF A MAGNETRON  AS IS NEEDED FOR PULSE COMPRESSION 4HUS  POWER AMPLIFIERS ARE ALMOST ALWAYS USED FOR PULSE COMPRESSION APPLICATIONS -AGNETRONS ARE NOT STABLE ENOUGH TO BE SUITABLE FOR VERY LONG PULSES EG   §S   AND STARTING JITTER LIMITS THEIR USE AT VERY SHORT PULSE WIDTHS EG   §S   ESPECIALLY AT HIGH POWER AND AT THE LOWER FREQUENCY BANDS )TS MAXIMUM AVERAGE POWER IS OF THE ORDER  OF SEVERAL KILOWATTS  WHICH IS LESS THAN THAT REQUIRED FOR SOME MILITARY APPLICATIONS . £ä°£È  2!$!2 (!.$"//+  3INCE THE MAGNETRON IS AN OSCILLATOR WITH A RANDOM STARTING PHASE ON EACH PULSE  IT CAN 
 (Receiver detection-criteria for compensating the effects of a change in clutter sta­ tistics with high resolution are discussed later in this section.) Third, if the pulse is too short, it  might encompass only part of a large target such as a ship, and the target cross section might  be reduced. However, if the echoes from the various parts of a large target are displayed  without collapsing loss and if the operator knows the general shape of the target, there will be  little, if any, loss in detectability.  Antenna beamwidth. 
  "     
 TO 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 have in the past been referred to as bipolar videos, but a more correct terminology is  that of the complex envelope of the received signals. 
 Inanormalfrequency-scan radar,thebeamdwellsateachangular resolution cell(beam­ width)foroneormorepulserepetition intervals. Another method forutilizing thefrequency domain toscananangular regionistoradiateasinglefrequency-modulated pulsewitha modulation-band wideenoughtoscanthebeamovertheentireangular region.Thus,overthe duration ofasinglepulse,theantenna beamscansallangles.Thisissometimes cal.ledwithin­ pulsefrequency scanning. 66.122(Thetermwithin-pulse scanning hasbeenapplied toother methods ofscanning, asdescribed inSec.8.7.)Thetransmitted waveform issimilartothe frequency-modulated pulsecompression waveform (chirp)discussed inSec.11.5.Thecarrier frequencies ofanyechopulsesreturned totheradarwillbedetermined bytheelevation angle ofthetargets.Thereceiver employs abankoffilters,eachtunedtoadifferent carrierfrequency whichinturncorresponds toadifferent angle.Thisisanalogous totheoutputofabeam­ forming matrix,asinSec.8.7.Thenumber offiltersdepends ontheantenna beamwidth and. 
 Naturally occurring dihedrals, such as rough rock for - mations created by a large impact, could generate false water-ice signatures. To reduce  the potential ambiguity of CPR and brightness measurements, the radar observations  must be repeatable and should be correlated with other indicators. Chandrayaan-1 and the Lunar Reconnaissance Orbiter (LRO)  include in each of  their payloads a “Mini-RF” radar.110 The version for Chandrayaan-1 is at S-band (12-cm  wavelength), with 150-m resolution at 16 looks. 
 The chief factor that made this  possible was the introduction of reliable. small, and inexpensive digital processing hardware.  CHAPTER FOUR MTIANDPULSEDOPPLER RADAR 4.1INTRODUCTION Thedoppler frequency shift[Eq.(3.2)]produced byamovingtargetmaybeusedinapulse radar.justasintheCWradardiscussed inChap.3,todetermine therelativevelocityofa targetortoseparate desired moving targetsfromundesired stationary objects(clutter). 
 GATE AND VELOCITY 
 It is not enough to match one element in the pres - ence of all its terminated neighbors. The element will deliver power to its neighbors,  and this loss in power corresponds to the average power lost when scanning. An  ideal, although not necessarily realizable element pattern, would place all the radiated  power into the scan region, giving a pattern like a cosine on a pedestal and thereby  providing maximum antenna gain for the number of elements used. 
 Thus,  AREPS contains a fairly simplistic pulsed-radar model to calculate free-space propaga - tion loss from radar system parameters such as frequency, pulse length, etc. The models  to do this calculation are taken from Blake28 and are fully described within the AREPS  online help and the AREPS operator’s manual. Thus, AREPS’ radar system assessment  model will not be repeated here. 
 .The target echo  causes a detection and initializes the motion estimation channel. The high [fine]  resolution data are initially smoothed in range to decrease [coarsen] the range reso - lution. Then the processor looks for the range cell with the maximum energy content  and computes the WVD [Wigner-Ville Distribution48] of that cell only. 
 The purpose or unequal element spacing in a highly thinned array is to eliminate the  grating lobes that would appear if equal element spacings of large value were used. Grating  lobes are not necessarily undesirable, since the energy contained in the grating lobes can be  used to detect targets. However, if this energy is distributed in the sidelobes by employing  unequal spacings, it is wasted. 
 If the sea surface is disturbed by the wind, the resulting  fine-scale roughness decreases the power of the pulse reflected back to the altimeter.  Hence, for wind speeds of more than about two knots, WS is inversely related to mean  waveform power. In practice, the inflections of the idealized flat-surface response  function waveform are softened by the pulse weighting, and the waveform is attenu - ated over time by the weighting of the antenna pattern. 
 Relaxing the Brightness Constancy Assumption in Computing Optical Flow ; A.I. Lab Memo 975; Massachusetts Institute of Technology: Cambridge, MA, USA, 1987. 32. 
 HAND SIDE IS DOMINATED BY THE RADAR MEASUREMENT NOISE COMPONENT "ECAUSE THE GAINS HORIZONTAL AXIS  ARE THE DESIGNERS CHOICE  THE SINGLE RADAR 2/5 IS THE MINIMUM OF THE hBATHTUBv CURVE .OW CONSIDER THE FUSION OF TWO RADARS IN A PARTICULAR DIMENSION )F ONE RADAR HAS ONE 
 Simrson. JI. R.: Performance Measures and Optimization Condition for a Third-Order Sampled­ Data Tracker. 
 AMPLITUDE INTERNAL WAVES  )N A MORE SUBTLE WAY   MODULATED CURRENTS ARE HELD RESPONSIBLE FOR SYNTHETIC APERTURE RADAR 3!2  IMAGES THAT CONTAIN THE EXPRESSION OF BOTTOM TOPOGRAPHY PRODUCED BY THE "ERNOULLI %FFECT IN SHALLOW WATERS  )N EACH OF THE EXAMPLES CITED ABOVE  THE CURRENT PRODUCES A CHANGE  IN THE SURFACE ROUGHNESS  WHICH CAN BE EXPECTED TO GIVE RISE TO A CHANGE IN SEA CLUTTER CROSS SECTION #ONTAMINANTS  4HE IDEA OF POURING OIL ON TROUBLED WATERS IS A FAMILIAR ONE THE  ANGRY SURFACE WILL SMOOTH AND SUBSIDE )N ANOTHER AGE  THE SURVIVAL 
 This sweep may represent either asmall part ornearly allofthe period between successive pulses. Inthe former case, the particular range interval that appears onthe display isdetermined bythe delay elapsing between the transmission ofthe outgoing pulse and the starting ofthe range sweep. The general classification “type A” isused todescribe one-dimen- sional displays. 
 OPTIMUM (OWEVER  SUCH SOURCES MAY HAVE GREATER POWER AND ANTENNA GAIN AT THEIR DISPOSAL  ALLOWING THE SIGNALS TO REACH THE RADAR RECEIVER WITH APPRECIABLE STRENGTH  SOMETIMES AFTER PROPAGATION VIA HIGHLY DISTURBED AND NONSTATIONARY IONOSPHERIC PATHS AS COMMONLY OCCURS IN THE EQUATORIAL AND POLAR REGIONS  5NDER NORMAL CIRCUMSTANCES  /4( RADARS SEEK TO FIND RELATIVELY CLEAR FREQUENCY CHANNELS IN THE USER 
 SIGHT 4HIS CAN BE IMPORTANT IN HARBOR  RIVER  ISLAND  AND ESTUARY REGIONS  WHERE SHIELDING BY THE TERRAIN OR BUILDINGS CAN AFFECT RADAR RANGE ! SHIPBORNE !)3 STATION BROADCASTS INFORMATION DIVIDED INTO A NUMBER OF SETS  4HESE COMPRISE STATIC DATA  SUCH AS THE SHIPS NAME  TYPE  LENGTH  AND BEAM DYNAMIC DATA  INCLUDING POSITION  3/'  #/'  AND HEADING AND VOYAGE 
 Figure 12.11 shows a series of actual pulses, followed by a series of samples at range R1. The spec- trum of Fig. 12.10 is the spectrum of the envelope of samples at R1 (after low- pass filtering). 
 The root ofthe difficulty isthat wehave todowith astatistical problem, agame of chance. The answers will begiven asprobabditics, and will depend upon many features ofthesystem bywhich thesignal ispresented tothe observer, aswell asupon the precise description ofthe “reasonable certainty” mentioned above. We approach theproblem byexamining first the character ofthenoise fluctuations. 
 The measured radar cross section of a man has been reported3* to be as follows:  Frequency, MHz 0, m2  The spread in cross-section values represents the variation with aspect and polarization.  44INTRODUCTION TORADAR SYSTEMS Table2.2Example radarcrosssectionsatmicrowave frequencies Squaremeters Conventional, unmanned wingedmissile Small,singleengineaircraft Smallfighter,or4-passenger jet Largefighter Medium bomber ormedium jetairliner Largebomber orlargejetairliner Jumbojet Smallopenboat Smallpleasure boat Cabincruiser Shipatzerograzing angle Shipathighergrazing angles Pickuptruck Automobile Bicycle Man Bird Insect0.5 1 2 6 20 40 100 0.02 2 10 SeeEq.(2.38) Displacement tonnage expressed inm2 200 100 2 1 0.01 10-5 where (J=radarcrosssectioninsquaremeters,f=radarfrequency inmegahertz, andDisthe ship's(fullload)displacement inkilotons.31Thisexpression wasderivedfrommeasurements madeatX,S,andLbandsandfornavalshipsrangingfrom2000to17,000tons.Although it isprobably validoutside thissizeandfrequency range,itdoesnotapplytoelevation anglesotherthangrazingincidence. Athigherelevation angles,asmightbeviewedfrom aircraft, thecrosssections ofshipsmightbeconsiderably lessthanatgrazing incidence, perhaps byanorderofmagnitude. 
 m2  R = range to target, m  L,, one-way propagation loss  L., system losses  The corresponding equation for the bistatic radar is  I 'r histatic  whnc < ;, -,--transmitting antenna gain in direction of target  (i, = receiving a11te1111a gain in direction of target  n,. = histatic cross section. m2  IJ, = transmitter-to-target distarn..:c. 
 RADAR CLUTIER 515 85.Beasley.E.W.:EffectofSurface Reflections onRainCancellation inRadarsUsingCircular Polariza­ tion.ProcIEEE.vol.54.pp.2000-"2(Xll.December: 1966. 86.Kalafus. R.M.:RainCancellation Deterioration DuetoSurface Rellections inGround-Mapping RadarsUsingCircular Polarization. 
 transfers theproblem ofexcessive accelerations tosome otherdirection; inthiscase,inthedirection oftheelevation axis.Athree-axis mountavoids theproblem ofexcessive acceleration. Thetwo-axis mountof(d)issimilarto(c)exceptthatitisarranged toprovide roll stabilization. Therolldatafromastableverticalcanbeappliedtothebasicrollaxiswithout theneedforcomputer ordersasrequired intheothertwo-axis mounts. 
 The doppler frequency shift of the echo signal from a moving target also provides a measure of radial velocity. However, the doppler frequency measurement in many pulse radars is highly ambiguous, thus reducing its utility as a direct measurement of radial velocity. When it can be used, it is often preferred to successive range measurements since it can achieve a more accurate measurement in a shorter time. 
 71. Aydin, K., T. A. 
 They  represent contiguous time (or range) samples with  3. 125-nanosecond (47-centimeter) resolution. A typical  ocean-return shape for a 2-meter wave height is shown  in Fig. 
 AGED  THE OVERALL WAVEFORM SET CAN RESULT IN BEING hSMEAREDv SPATIALLY IF THE RADAR IS MOVING AT ANY SPEED 4HE STABILITY OF THE TIMING INCREMENT IS VERY IMPORTANT AND GEN 
 PRF of the radar. The abscissa can also be interpreted as the ratio of the doppler frequency to the average PRF of the radar. The canceler configurations shown are not the most general feedforward, feedback networks possible but, rather, are practical configurations easy to im- plement. 
 Long, “Tradeoffs in the design of a spaceborne scanning pencil  beam scatterometer: Application to Sea-Winds,” IEEE Transactions on Geoscience and Remote  Sensing , vol. 35, pp. 115–126, 1997. 
 AMPLITUDE MODULATION0 D  PROBABILITY OF DETECTION 0#  PULSE COMPRESSION0$)  POSTDETECTION INTEGRATION NONCOHERENT INTEGRATION 0 &!  PROBABILITY OF FALSE ALARM 0-  PHASE MODULATION00-  PULSE 
 62. Orbital Maneuvering Vehicle, NASA George C. Marshall Space Flight Center, Re- quest for Proposal l-6-pp-01438, November 1985. 
      
 DOWN GEOMETRY OF SKYWAVE ILLUMINATION RESULTS IN STRONG CLUTTER RETURNS  IN THE SAME RANGE CELL AS THE TARGET  DEMANDING A HIGH DYNAMIC RANGE ABLE TO SUPPORT CLUTTER 
 TheReceiver.—The receiver isconventional, with ani-fbandwidth of1.8Me/see and anover-all gain ofslightly more than 120db. Instan- FIG.15.7.—Duplexing assembly. Two such units are included, one for upper-beam system and one for lower-beam system. 
 FREQUENCYA GREAT ADVANTAGE WHEN THE RADAR IS MOVING  SUCH AS FOR 3!2AND   THE HARDWARE IS RELATIVELY INEXPENSIVE AND MATURE ,&- HAS BEEN SUCCESSFULLY EMPLOYED OPERATIONALLY  EG  IN THE 5 3 .AVY !.!03 
 Further trials were undertaken by ASWDU in 1945 [ 18] of an ‘improved ’discriminator, assessed in ASV Mk. VI and VIA in three Wellington Mk. XIV aircraft, with rada rs having sea return discriminators modi ﬁed by TRE. 
 Lee, Y. W., and J. B. 
 RATELY IN A LATER SECTION.   3%! #,544%2  £x°Î £x°ÓÊ / 
 80 HOW RADAR WORKS  discharge, or, graphically, [\/\_; and not | /|, as in  the previous circuits described. This circuit acts on the  principle of the ‘squegging’ oscillator, but it is important  to note that the sweep frequency is not directly related  to the frequency of the oscillations set up in the circuit,  e  HLT. ate  R  Swe  Volt ace  Synch. 
 Geosci. Remote Sens. 2010 ,48, 770–780. 
 The mainlobe of the compressed pulse at the output of the matched filter has time,  or range, sidelobes that occur within time intervals of duration T, before and after the  peak of the peak of the compressed pulse. The time sidelobes can conceal targets,  which would otherwise be resolved using a narrow uncoded pulse. In some cases, such  as phase-coded waveforms or nonlinear frequency modulation waveforms, matched  filter processing alone achieves acceptable time sidelobe levels. 
 For example, a C-band phase shifter, operating over an 8 percent  bandwidth was capable of handling 100 kW of peak power at an average power of 600 W. The  insertion loss was 0.9 dB with a maximum VSWR of 1.25. However, it required 125 /rs to  switch the phase. 
 (Prior knowledge ofthecharacteristics ofthetrajectory canbeincorporated inthemodel,as,for example, whenthetrajectory isknowntobeballistic.)Ifthedifference between theprediction andthemeasurement iszero,noadjustment ismadeandtheantenna mountispointed according tothestoredprediction. Iftheydonotagree,thetargettrajectory prediction is changed untiltheydo.Thus,thepointing oftheantenna ismadeopen-loop basedonthe storedtarget-trajectory prediction updated bytheradarmeasurements. Theservoloopthat pointstheantenna ismaderelatively wideband (highdatarate)topermitafasttracking response againsttargetswithhighangularacceleration. 
 = 70 cm) at zero degrees grazing angle responds to water waves of length  35 cm. These are known as gravity waves.  The effect of the large water waves is to cause a tilting of the scattering surface or the  smaller water waves, as in Fig. 
 THE 
 J. H. Dunn and D. 
 , 
 The experimental data collected on the wide-area surveillance mode of an airborne radar system is selected. The experiment radar parameters are illustrated in Table 2. T able 2. 
 55, pp. 587-S89,  April, 1967.  42. 
 DITIONAL VACUUM TUBE  OR A SOLID 
 Orle set of data5 gives the value of o0 at short wave-  lengths to be proportional to U-' 6, where U is the wind speed.  'T'hc wiriti has been assunled liere to be a driving force in determining tlie radar back-  scatter frotri tlie sea. It is itldccd, but tllc relation between the wind and the sea conditions is  cotnplex: Iiencc, so will be the relation between the'wind and the radar backscatter. 
 36. Roherts, J. 8. 
 FIG. 18.23 Azimuth-tracking error for the passing-course target. (From A. 
 Marks, and A. ~loosfer: Coherent Optical Processing of Synthetic Aperture Radar  Data, Proc. Soc. 
 12 by hail, 19.11 to 19.12 by rain, 19.8 to 19.11 Automatic detection, 7.1 to 7.2, 7.20 to 7.22 Automatic gain control (AGC), in monopulse tracker, 9.5, 9.10 to 9.11 Automatic Identification System (AIS) in civil marine radar, 22.23 to 22.25 in search and rescue, 22. 27 Automatic noise-level control, 6.23 to 6.24 Automatic Radar Plotting Aid (ARPA), 22.17 Automatic tracking, 7.22 to 7.46 alpha-beta (/g302-/g533) filter, 7.26 to 7.27, 7.30 detection acceptance, 7.25 to 7.26 I nteracting Multiple Model (IMM), 7.35 to 7.37 Kalman filter, 7.28 to 7.35 new track formation, 7.41 to 7.46 retrospective processing, 7.42 to 7.43 scheduling and control, 7.46 track association, 7.38 to 7.41 track file, 7.23 to 7.25 updating tracks, 7.26 to 7.30 AWACS, 13.65 B B-2 low cross section aircraft, 14.18, 14.42 Ballistic missile defense, 13.54 Bandwidth importance of, 1.8 to 1.9 of phased arrays, 13. 38 to 13.45 receiver, 6.9 Bar, in airborne radar, 5.15 to 5.16 Barker codes, 8.17. 
 This figure of merit is more representative of a " searchlighting "  radar and not a surveillance radar.  Ground-wave OTH radar. The type of OTH radar described in the above that propagates vra  refraction from the ionosphere is sometimes called a sky-wave radar. 
 WARNING !%7   RADARS WERE DEVELOPED BY THE 53 .AVY TO DETECT LOW 
 vol. IT- I. pp. 
 Mattern: Receivers, chap. 5 of "Radar Handbook," M. I. 
 Cf~andler, R. A,. and L. 
 28. J. C. 
 Its chief limitation is that the target must be  in the presence of relatively large clutter signals if moving-target detection is to take place.  Clutter echoes may not always be present over the range at which detection is desired. The  clutter serves the same function as does the reference signal in the coherent MTI. 
 Further laboratory70 and theoreti - cal71 studies have shown that the major scattering feature under these conditions is the  vertical stalk  that emerges shortly after drop impact. Moreover, these studies suggest  that the V-polarized returns from raindrop splashes should be only mildly sensitive to  the rain rate, while the H-polarized returns should show a strong dependence on both  the rain rate and the drop-size distribution. Something of this behavior may be seen  in the data in Figure 15.17. 
 #/5.4%2-%!352%3   Ó{°{ FORMATION IN ORDER TO REDUCE THE SPECKLE NOISE 4RADITIONAL DIGITAL MULTILOOK PROCESSING  CONSISTS OF AN INCOHERENT ADDITION OF INDEPENDENT IMAGES LOOKS  OF THE SAME SCENE 4HE LOOKS CAN BE OBTAINED BY PARTITIONING THE AVAILABLE SIGNAL BANDWIDTH RANGE ANDOR AZIMUTH  AND PROCESSING EACH LOOK INDEPENDENTLY 4HE FINAL IMAGE IS PRODUCED BY ADDING THE LOOKS INCOHERENTLY  PIXEL BY PIXEL 4HE DIRECT TRADE 
 V.: Survey  of Radar Signal Processing, Naval Research Laboratory Report 81 17, Washington, D.C., June 21,  1977.  64. Hansen, V. 
 They will thus work with thelower beam ofthesetjust described, but notwith theupper beam since thelatter is horizontally polarized. The beacon isarranged tobetriggered bythe pulses from theradar, but itreplies onadifferent frequency, toreceive which anentirely separate beacon receiving antenna and receiver system areprovided. The beacon antenna, mounted ontop ofthelower-beam radar antenna, isshown inFig. 
 One of the major  factors in this regard has been the introduction of digital devices for conveniently computing  the Fourier transform.  Digital filter banks and the FFT. A transversal filter with N outputs (N pulses and N - 1  delay lines) can be made to form a bank of N contiguous filters covering the frequency range  from 0 to f,, where .fp = pulse repetition frequency. 
 In one example. it was shown that the fading is strongly  dependent on the radar and the target heights, and that for centimeter wavelengths the fading  occurs at intervals of from two to three miles.  The height of the evaporation duct, from which the propagation conditions can be in­ ferred, can be readily calculated from measurements of the surface water temperature and. 
 3/* IS BASED ON ESTIMATING THE  JAMMER POSITION AND POWER LEVEL AND THEN USING  SUCH ESTIMATES TO ADAPT THE RADAR DETECTION THRESHOLD ONLINE u *AMMER STATE ESTIMATION 7HENEVER THE RADAR OPERATES IN THE PASSIVE MODE  IE  WITH 
 1514] L)I?T.4ILED L).ESIG.V OF THE A.Y”/APS-10 625 sweeps between 15and 50miles, and 20-mile marks onthebeacon sweeps. 2.Arecei~’er gain control. 3.Atilt control forthe antenna. 
 A typical metal space-frame radome of this type might have . RADAR ANTENNAS 267  a transmission loss of 0.5 dB and cause the antenna side!obes to increase an average of 1 dB at  the 25 dB level. The boresight might be shifted less than 0.1 mrad and the antenna noise  temperature might increase less than 5 K.136 Approximate formulas are available for predict­ ing the electrical eITects (gain. 
 DIMENSIONAL COMPONENT  WHERE  6 IS THE VECTOR AIR MOTION AND IS CONSTRAINED TO BE ZERO AT THE  SURFACE  4HE VERTICAL AIR  MOTION IS CALCULATED FROM VERTICAL INTEGRATION OF THE MASS CONTINUITY EQUATION &IGURE  ILLUSTRATES AN AIR MOTION FIELD OBTAINED BY TWO DOPPLER RADAR OBSERVA 
 OPTICAL %/  SENSORS  STORES MANAGEMENT   &)'52%  -&!2 MERGED WITH OTHER SENSORS ADAPTED  . x°{  2!$!2 (!.$"//+  VEHICLE MANAGEMENT  PILOT 
 B. Mack, “Basic design principles of electromagnetic scattering measurement facilities,”  Rome Air Development Center Rept. RADC-TR-81-40, March 1981. 
 Hetland, E.; Mus é, P .; Simons, M.; Lin, Y.; Agram, P .; DiCaprio, C. Multiscale InSAR time series (MINTS) analysis of surface deformation. J. 
 8.6. Each phase bit consists of two lengths of line that provide the differential phase shift,  and two single-pole, double-throw switches utilizing four diodes.  The hybrid-coupled phase bit, as shown in Fig. 
 _ I · 0.443A. 0.443A. o + -00 = sm Nicos--0~ :::::: Nd cos Oo  -0.443J -0.443J (}_ -00 = sin-• ··------::::::------------Nd cos 00 Nd cos 00 . 
 Storing the radar picture onanimage orthicon orother storage device which can berapidly scanned electrically toproduce tele- vision signals. This method, although not well developed atthe end ofthewar, holds great future promise. Use ofadark-trace tube, or“skiatron. 
 We then look at the apparatus  moving the spot of light, and make sure that it is causing  it to move at an absolutely constant speed, so that the  spot does not travel faster along one part of the apparent  line than it does along another. Of course, we could  never do this with a mechanical lever, for it would have  inertia and would take an appreciable time to get going  at the start of the line, and would need to be slowed down  before the end. But our electron lever has no appreciable  . 
 be required even with some for111 of r~~echanically stabilized mounts. Data stabilizatioli is  usually used with pencil-beam tracking antennas. A computer can readily calculate the angu-  lar corrections to the output data to account for platform tilt. 
 AES , vol. 39, pp. 110–124, January 2003. 
 272-273, February, 1970.  43. Skolnik, M. 
 Itisnotsufficient thatonlythefirststageofalow-noise receiver haveasmallnoisefigure.The succeeding stagemustalsohaveasmallnoisefigure,orelsethegainofthefirststagemustbe highenoughtoswampthenoiseofthesucceeding stage.Ifthefirstnetwork isnotanamplifier butisanetwork withloss(asinacrystalmixer),thegainG1shouldbeinterpreted asanumber lessthanunity. ThenoisefigureofNnetworks incascade maybeshowntobe F=F+F2 -I+F.].-=l+...+__.!:~_-=-~_ o 1GtG1G2 G1G2'''GN-1 Similarexpressions maybederived whenbandwidths and/orthetemperature oftheindividual networks are{f1ot thesame.) Noisetemperature. Thenoiseintroduced byanetwork mayalsobeexpressed asaneffective noisetemperature, T..,definedasthat(fictional) temperature attheinputofthenetwork which wouldaccount forthenoiseliNattheoutput.Therefore Ii.N=kTeBnGand (9.6) (9.7) Thesystemnoisetemperature I:isdefinedastheeffective noisetemperature ofthereceiver systemincluding theeffectsofantenna temperature Ta.(Itisalsosometimes calledthesystem Figure9.1Twonetworks incascade.. 
 744 RADAR SYSTEM ENGINEERING Pillbox, 276 Pip-matching, 203 Plan-position indicator, 6,167 (See ah. PPI) Plotting board, 180°, 238 verticrd, 235 x-Y, 240 Polyrod, 278 Polyrod radiators, array of,303 Pound, R.V.,717, 724 Power, formobile radar, 585 prime, supplies forradar, 555-587 forradar, inaircraft, 555-583 frequency of,555 recommendations for, 582 attied locations, 583 forlarge systems, locally generated, 584 forshipborne systems, 586 Power frequencies, inaircraft, standard, 556 Power supply, 3-phase a-cradar, 559 forultraportable equipment, 585 vibrator, 581 PPI, 167 delayed, 169 deeign of,532-545 off-center, 168 open-center, 169 pm-time-base resolution for, 544 resolved-current, 538-545 reached time bsse, 534–538 rotating-coil, 534 stretched, 170 threAone, 553 using automatic transmitter triggering, 540 PPI displays, contraat of,54*554 resolution of,548-554 Pre-plumbing, 408 Prwwrization, ofr-flines, 283, 420 PRF, choice of,598 Prime movers, small, 586 Prime power supplies for radar (see Power, prime, supplies forradar) projector, chart, 215 Propagation, free-space, 18 ofmicrowaves, over reflecting surface, 47-53 (sss ah. Microwave propagation) PSWR (see Standing-wave ratio, power)Pulse, phaae-shifted, 697 sharp, generation of,501-503 pulse cable, 386 pulse length, choice of,596-598 pulse modulation (see Modulation, polae) pulse packet, 122 pulse power (see Magnetron, pulse power of) P@e-forming network (see Network, pulseforming) Pulse-modulated doppler system, 150-157 Pulee-to-pulse cancellation, 631 Pulse recurrence frequency (see PRF) Pulee transformers, 38L-386 Puk3er, 353-390 basic circuit, 356-36o driver circuit, 371 energy sources of,387 hard-tube, 367-373 hard-tube and linetype, comparison of,3W363 line-type, 358, 374-383 a-ccharging of,383 recharging circuit of,382 switches for, 377–381 overload protection of,364 Pulser switch, 357 forline-type pulsers, 377–381 nonlinear inductance as,381 Pulser switch tubes, high-vacuum, 368 Q Q,ofcavity, 406 Quarter-wave line (see Line, quarter- wave) Quarter-wave plate, 84 R Racons, 246 Radar, 419 comparison of,with eye, 1 C-W, 127–159 comparison with pulse radar, 123 ground, use ofbeacons with, 609 history of,13 limitations of,116-126 prime power supplies for (see Power, prime, supplies forradar) principle of,3-6. 
 PERIOD VELOCITY RESPONSE CURVES )F  USING FOUR INTERPULSE PERIODS MAKES THE FIRST NULL TO BE TOO DEEP  THEN FIVE INTERPULSE PERIODS MAY BE USED  WITH THE STAGGER RATIO OBTAINED BY ADDING THE FIRST BLIND SPEED TO THE NUMBER  
 DETECTION FUNCTIONS  SUCH AS INTRAPULSE MODULATION MEASUREMENT AND WAVEFORM CODE RECONNAISSANCE 0ULSE WIDTH IS AN UNRELIABLE SORTING PARAMETER BECAUSE OF THE HIGH DEGREE OF CORRUP 
    8I    &)'52%   2ANK DETECTOR OUTPUT OF A COMPARATOR # IS EITHER A ZERO OR A  ONE FROM ' 6 4RUNK . 
    
 88-91, March, 1964.  11. Ru1e. 
 And there is another complication. The individual ocean wave trains are  not completely independent—they interact weakly and produce evanescent nonlinear  product waves that, while not freely propagating, change the geometry of the sea  surface and contribute to the scattered field at second order, also via Bragg scattering.  Thus, as shown first by Barrick,81 the second-order scattering kernel is made up of  electromagnetic and hydrodynamic terms, Γ Γ Γ = +EM HYD. 
 SEC.215] ATTENUATION OFMICROWAVES 61 measured, forinstance, ingrams per cubic meter. 1The effect oflarger drops ismore complicated, depending not only upon the total mass of water perunit volume, but upon thediameter ofthedrops aswell. The absorption process itself isnolonger simple, and scattering ofenergy by the drops, which depends very strongly onthe ratio ofwavelength to drop diameter, begins toplay arole. 
 S/N (dB) FIG. 8.7 Angular accuracy using two-pulse estimates. Feedback Integrator. 
 TION $"& IS USUALLY PREFERRED WHEN A LARGE NUMBER OF BEAMS ARE TO BE FORMED £Î°£ÓÊ  / Ê 
 A typical GPR achieves a range of up to  a few meters, but some special systems can penetrate up to hundreds of meters or even  kilometers. A few GPR systems have been operated from aircraft and from satellites  to image geological features buried beneath the Saharan deserts as well as measuring  the depth of the Moon and features on Mars or comets. The range of the GPR in the  ground is limited because of the absorption the signal undergoes, while it travels on   its two-way path through the ground material. 
 The primary feed should be designed  with care and can be complex to give the desired aperture amplitude distribution with  low spillover losses. The transmitter feed can be separated from the receiver feed by  an angle a , as shown in Figure 13.30. The phase shifters are then reset between trans - mitting and receiving so that in both cases the beam points in the same direction. 
 Similar  results were noted for the improvement in a conventional PPI when the pulses were displayed  side-by-side.  In other experiments with the PPI, the integration improvement has been reported to be  proportional to 1.5 dB per doubling of the number of pulses, which corresponds to n"2.50  Improvements as high as 1.8 dB per doubling were also observed, but this is less than the 2.2 to  386INTRODUCTION TORADAR SYSTEMS moreinformation thaneithertheenvelope orthezero-crossings detector. itisnotsurprising thatthesignal-to-noise.ratio fromthecoherent detector isbetterthanfromtheothertwo.The improvement inthesignal-to-noise ratiomightvaryfrom1to3dBormore,overtherangeof signal-to-noise ratiosofinterest inmostradarapplications. 
 Ê-9-/ 
 RADAP. SYSTEM ENGINEERING COPYRIGHT, 1947, BY THE J1cC,R,iW-HILL BOOKCoMP.iNY,INC. PRINTELIIXTHEUNITEDSTATESOFAMERI(..< Aulr!qhhrf?send ‘1’hishook., or pert:ihrrrqf, ?na~jno!hereprod7wd in07(vJm-TII wilhottl permission oj thepublishers. 
 18.27 nth-Time-Around Tracking  .................................  18.30  18.6 Special Monopulse Techniques  ..............................  18.30  High-Range-Resolution  Monopulse  .................... 
 For the same reason, combining the power outputs of magnetrons has not been attractive. 5. If coded or shaped pulses are required. 
 Dax, “Accurate tracking of low elevation targets over the sea with a monopulse radar,”  in IEE Radar Conf. Publ . 105, Radar—Present and Future , London, October 23–25, 1973,   pp. 
 MONOSTATIC   TRISTATIC   POLYSTATIC   REAL MULTISTATIC   MULTI 
 For exam­ ple, a linear phase error across the antenna aperture causes the beam position to tilt in angle. A  quadratic, or square-law, variation in phase is equivalent to defocusing the antenna. A period it:  error with fundamental period pf)., where pis measured in the same units as is the wavelength  1, will produce spurious beams displaced at angles <Pn from the origin, according to the relation  sin <Pn n}../p, where n is an integer. 
 VEILLANCE  THEY ALSO HAVE SOME SERIOUS LIMITATIONS $EEP NULLS IN ELEVATION AND POOR LOW 
 D.K.•andW. W.Shrader: Interclutter Visibility inMTISystems, IEEEEASCON '69 CO/welltion Record.pr.294-297, Oct.27-29,1969,IEEEPublication 69C31-AES. 46.Barton. 
 vol. AES-7, pp. 160-170, January, 1971. 
 the element pattern, it may be prudent to space the elements such that the first null of the grating lobe, rather than the peak, occurs at 90°. With N elements this more restrictive condition is given by ' N ~ 1 x 1 (711) XN 1 + lsin B0I Equation (7.8) may again be approximated by the Fourier transform of the il- lumination across the continuous aperture: sin ir(0/X)(sin B - sin B0)E(B) = V2(I + cos B) . —— (7.12) TT(a/\)(sin B — sin B0) The Fourier-transform solutions for continuous apertures19'43 may be used to approximate patterns for practical amplitude and phase distributions as long as the element-to-element spacing is small enough to suppress grating lobes.44 Monopulse difference patterns may be approximated in the same way from the Fourier transforms of the corresponding continuous odd aperture distributions. 
 575–576, 1988. 131. E. 
 16.1  16.1 Systems Using Airborne MTI Techniques  ..............  16.1 16.2 Coverage Considerations  .......................................  16.2  16.3 Platform Motion and Altitude Effects on MTI  Performance  ........................................................... 
 S. Zrnic ′, Doppler Radar and Weather Observations , 2nd Ed., Mineola, NY:  Dover Publications, 2006. 24. 
 The usual receiver, however, has some non - linearities due to detector properties and to  saturation of its amplifiers by large signals.  Figure 16.13 shows a typical input-output  curve for a receiver. Two equal increments  in input signal ( ∆i), as shown, produce dif - ferent increments in output because of the  nonlinearity of this curve. 
 Itsvalueat aparticular samplepointisunity,butitiszeroatallothersamplepoints.]naddition, the (sint/J)!t/Jfunction canbereadilygenerated withauniform aperture distribution. The Woodward-Levinson synthesis technique 'Consists indetermining theamplitude andphaseof theuniform aperture distribution corresponding toeachofthesamplevaluesandperforming asummation toobtaintherequired overallaperture distribution. Theaperture distribution maybefoundbysubstituting theantenna patternofEq.(7.26) intotheFourier-transform relationship givenbyEq.(7.14).Theaperture distribution becomes (7.27). 
 WHAT ELEVATED HAVE THE SIGNAL MODIFIED BY THE EFFECT OF MULTIPATH INTERFERENCE BETWEEN  &)'52%     !PPARENT  RELATIVE  DIELECTRIC  CONSTANT  VERSUS  MOISTURE CONTENT 2ICHFIELD SLIT LOAM  AFTER * 2 ,UNDIEN     !NGLE OF REFLECTION EQUALS ANGLE OF INCIDENCE.   '2/5.$ %#(/  £È°Ç THE DIRECT RAY AND ONE REFLECTED OFF THE GROUND 3INCE THE SCATTERING FROM RELATIVELY  LEVEL SURFACES IS VERY SMALL  ANY PROJECTION MAY GIVE A RETURN MUCH STRONGER THAN THE BACKGROUND  THEREBY SKEWING THE STATISTICS SO A 2AYLEIGH DISTRIBUTION NO LONGER APPLIES TO THE AVERAGE SIGNAL /BJECTS SUCH AS TREES  BUILDINGS  FENCE POSTS  AND POWER LINES GIVE LOCALIZED ECHOES STRONG RELATIVE TO THEIR SURROUNDINGS -OREOVER  THE SIGNAL FROM SURFACES WITHOUT PROJECTIONS FALLS OFF VERY RAPIDLY  FOR DEPRESSION ANGLES WITHIN A FEW DEGREES OF GRAZING 4HIS MEANS THAT THE EFFECT OF SMALL LOCAL SLOPES CAN BE VERY SIGNIFICANT IN MODULATING THE RETURN SIGNAL  NOT JUST IN SHADOWING £È°ÎÊ / 
 Alternatively, analytic ray-tracing can be performed on analytic profiles fitted to RTIM  databases. The most accurate predictions come from the application of sophisticated  ray-tracing routines to a database of RTIM snapshots. When a radiowave propaga - tion model is combined with radar system parameters, target scattering characteristics,  and HF noise distributions, the radar equation (Eq. 
 l.- I.--__ ---J ---J ---'27.5nmifree-space range;(6)contour o 10 20 30 40 50defining startofdiffraction region. Range,nauticalmiles (Courtesy Proc.IRE.)100+­....... PROPAGATION OF RADAR WAVES 459  represents the approximate boundary between the interference region and diffraction region. 
 Hence, the processing  QJ  D  .2  0.  E  <l  Distance  Figure J.18 Plot of J.1(/)) as a function of distance. (From Sa1111ders.9 IRE Trans.) . 
 V. RADAR TIME-BASES  VERY RADAR DEVICE WHICH DEPENDS ON TIME  ee ee must have a means of pulling the  CRT spot along a display path at a certain speed, so that  deflection from this path resulting from received signals  or other pulses can be read with relation to some fixed  standard.  The apparatus which moves the spot in this way is  known as the time-base, or more accurately as a time-  base generator. 
 SONIC AIRFRAME TO ACCEPTABLE LEVELS 4HAT BEING THE CASE  THEY DECIDED TO ANGLE ALL LEADING AND TRAILING EDGES AT A COMMON SWEEP ANGLE  n 4HEIR PHILOSOPHY WAS THAT  IF THEY COULDNT SUPPRESS THE EDGE RETURNS  THE NEXT BEST OPTION WOULD BE TO ANGLE THEM ALL INTO FOUR COMMON DIRECTIONS IN SPACE 4HUS  ALL TRAILING EDGES IN THE " 
 IRE, vol. 44,  pp. 755-760, June, 1956. 
 The Sequential  Observer makes a relatively prompt decision when only noise is present.  The average savings also depend upon whether detection is performed coherently or  noncoherently. Assuming coherent detection (pulses integrated predetection) and Pv = 0.90  and Pra = 10-8, the Sequential Observer is able to determine, on the average, that noise alone  is present with less than one-tenth the number of observations required for the Neyman­ Pearson Observer.90 In the presence of a threshold signal, the Sequential Observer requires,  on the average, about one-half the number of observations of the equivalent fixed-sample  observer. 
 PLANE DIMENSION IS THE SAME AS THE ACTUAL DIMENSION 'AIN /PTIMIZATION  4HREE OF THE PRINCIPAL REFLECTOR ANTENNA LOSSES  TAPER EFFI 
 W. Rotman and R. F. 
 PULSE RADAR AT HIGH  GRAZING ANGLES  OR   !F   CS  "2COSX    FOR PULSE 
 TO 
 However, this increases the total amount  of signal processing required. The envelope at the output of the FFT is formed with a linear ( I Q2 2+ ) or square- law ( I Q2 2+) detector. Historically, linear detectors were used to manage dynamic  range in fixed-point processors. 
 DIRECTED ANTENNA A REFLECTOR  IS HIDDEN INSIDE OF THE SOLAR ARRAYS 4HIS SPACECRAFT MAINTAINED VERTICALITY BY GRAVITY 
 CIENCIES AS LOW AS  4HE TYPES OF ANTENNAS THAT ARE USEFUL TO THE DESIGNER OF ULTRAWIDEBAND RADAR FALL  INTO TWO GROUPS DISPERSIVE ANTENNAS AND NONDISPERSIVE ANTENNAS $ISPERSIVE ANTENNAS HAVE A NONLINEAR PHASEFREQUENCY RESPONSE WHEREAS NONDISPERSIVE ANTENNAS HAVE A SUBSTANTIALLY LINEAR PHASEFREQUENCY RESPONSE %XAMPLES OF DISPERSIVE ANTENNAS THAT HAVE BEEN USED IN ULTRAWIDEBAND RADAR ARE THE EXPONENTIAL SPIRAL  THE !RCHIMEDEAN  &)'52%   2ADIATED FIELD PATTERN FROM A CONDUCTING DIPOLE ELEMENT DUE  TO AN APPLIED IMPULSE #OURTESY )%%  . Ó£°ÓÈ  2!$!2 (!.$"//+  SPIRAL  THE LOGARITHMIC PLANAR ANTENNA  THE 6IVALDI ANTENNA  SLOT ANTENNAS  AND THE EXPO 
 Ó°£Ó  2!$!2 (!.$"//+  WHERE K IS THE RADAR WAVELENGTH )NSTEAD OF THE STANDARD DEVIATION  SF  THE POWER SPEC 
 One such niche is com - mercial weather radar, e.g., NEXRAD and TDWR. V ery High-Gain, Long-Range Radar .  For very high-gain radar applications, the cost  of an ESA is typically still prohibitive, and the reflector provides an economical means of  realizing such high gains. 
 (13.17) into (13.16) yields  p -_nsP,G~_ I 12 "D6  ' -1024(ln 2)R2 l 2 K 7 (13.18)  Since the particle diameter D appears as the sixth power, in any distribution of precipitation  particles the small number of large drops will contribute most to the echo power.  Equation (13.18) does not include the attenuation of the radar energy by precipitation,  which can be significant at the higher microwave frequencies and when accurate measure­ ments are required. The two-way attenuation of the radar signal in traversing the range Rand  back is exp (-2tXR), where a is the one-way attenuation coefficient. 
 For one thing, there are several ways inwhich the echo in question can beidentified asoriginating from the preceding pulse. The useofaslightly irregular pulse-recurrence rate, forinstance, will prevent overlapping ofsuccessive echoes ofthis type from the same target, without affecting the superposition ofechoes from atarget lying within therange limit defined above. Ifamore powerful remedy isneeded, the unwanted echoes can beremoved altogether bysome such scheme as thefollowing one. 
 government budget authorities. The second was set by physics, conditional upon  the data-rate capabilities of the Deep Space Network.112 The lesson, of course, is that  it is not enough to do good (read “big budget, SBR-based”) science, it must be done  efficiently and relatively patiently. In the case of Magellan , however, these top-level  restraints motivated a superb innovative radar design. 
 CI CID DTD DTTK2DI     WHERE VC   CARRIER ANGULAR FREQUENCY  VDI   DOPPLER ANGULAR FREQUENCY FOR ITH TARGET  EI   PHASE FOR ITH TARGET  2I   RANGE FROM RADAR TO ITH TARGET 4HE DOPPLER SHIFT CAN BE EXPRESSED IN TERMS OF THE VELOCITY VECTOR V AS   WDI 
 Mortley, W. S .• and S. N. 
 Probably the most prominent source of angels is birds. Although the radar cross section  of a single bird is small compared with that of an ordinary aircraft, the backscatter echo from a  bird can be readily detected by many radars, especially at the shorter ranges, because of the  inverse-fourth-power variation of echo signal with range. If, for example, the cross section of a  bird the size of a sea gull were 0.01 m2, it would produce as large an echo signal al a range of  10 nmi as would a 100 m2 radar cross-section target at 100 nmi. 
 1130-1137, October 1994. 38. H. 
 It has the form S(f) = AT5e~B(fm/^ (13.3) where g is the acceleration of gravity, and/m = g/2irC/, corresponding to the fre- quency of a wave moving with a velocity equal to the wind speed U\ A and B are empirical constants. This spectrum is illustrated in Fig. 13.1 for several wind f (Hz) FIG. 
 2.2 INTRODUCTION TO MTI RADAR The purpose of MTI radar is to reject returns from fixed or slow-moving unwanted  targets, such as buildings, hills, trees, sea, and rain, and retain for detection or display  signals from moving targets such as aircraft. Figure 2.1 shows a pair of photographs  of a PPI, which illustrates the effectiveness of such an MTI system. The distance from  the center to the edge of the PPI is 40 nmi. 
 519  Forward scatter. 557  Fox phase shifter. 296-297  Fraunhofer region, antenna, 229 Frequency agility:  ECCM, 548  for glint reduction, 170-172  and sea echo, 485  Frequency diversity, 548 INDEX 575  Frequency measurement accuracy, 407-408  Frequency modulated CW radar, 81-92  Frequency-scan arrays, 298-305  Frequency-scan radar. 
 FILTER PROCESSING  4HE WIDTH OF THE COMPRESSED PULSE AT THE HALF 
 TION AT FREQUENCIES INTO THE 7 BAND 'A!S TRANSISTORS GENERATE LESS NOISE THAN SILICON DEVICES WHEN OPERATED AT HIGH FREQUENCY SO THEY ALSO MAKE SUPERIOR LOW 
 Curlander, J.; McDonough, R. Synthetic Aperture Radar: Systems and Signal Processing ; Wiley: New York, NY, USA, 1991. 6. 
 Although such events are relatively rare in a fixed area of 10 m2, they should occur quite frequently within a large surveillance cell and might often have large scattering cross sections associated with them. RELATIVE FREQUENCY (Hz) FIG. 13.15 Short-time averaged doppler spectra at X band for an intermediate grazing angle of 35°; spectra computed at 0.2-s intervals. 
 CONFIRM PROPERTIES A DOUBLE THRESHOLDING METHOD IN WHICH A LOWER FIRST THRESHOLD NOMINATES  RADAR RETURNS AS POS 
  D" )NTEGRATED 3IDELOBE 2ATIO )3,2   !N ACTUAL 03& TYPICALLY RESEMBLES THE THEO 
 RANGE IMAGING RADAR v 0ROJECT 2EPORT  03) 
 Measurements made on the middle Atlantic coast of the United States show HF broadcast-band signals with strengths of 5 to 10 mV/m. These ambient levels must be accommodated in re- ceiver design since a wideband front end is desirable for rapid and frequent fre- quency changes. The practice in allocations for HF radar operation is to permit use of broad bands of the spectrum with a requirement to cause no interference to an existing service and to provide a lockout feature for channels that need protection. 
 FIELD  REGION  7HEN THE TARGET IS SO CLOSE TO THE ANTENNA  IT INTERACTS WITH THE REACTIVE FIELDS OF THE ANTENNA  AND ACCURATE MODELS WOULD REFLECT THIS MODE OF OPERATION 4HE MOST BASIC MODEL USES THE RADAR RANGE EQUATION AND ENABLES AN ESTIMATE OF  RECEIVED SIGNAL LEVEL  DYNAMIC RANGE  AND PROBABILITY OF DETECTION TO BE ASSESSED )T HAS SIGNIFICANT WEAKNESSES IN THAT  MOST CLOSE 
 Antennas which must be operated in severe weather are usually enclosed  for protection in a sheltering structure called a radome. Radomes must be mechanically strong  if they are to provide the necessary protection, yet they must not interfere with the normal  operation of the antenna. Antennas mounted on aircraft must also be housed within a radome  to offer protection from large aerodynamic loads and to avoid disturbance to the control of the  aircraft and minimize drag. 
 As  we shall see later, this is a reasonable approximation for pulse radars with conventional  superheterodyne receivers. It is not generally valid for other waveforms, however, and is  mentioned to illustrate in a qualitative manner the effect of the receiver characteristic on  signal-to-noise ratio. The exact specification of the optimum receiver characteristic involves  the frequency-response function and the shape of the received waveform. 
 The impedance will also  vary with scan angle. For a finite array the properties vary with location of the element within  the array. In some arrays, dummy elements are placed on the periphery so as to provide tlie  eleriients near the edge with an environment more like those located in the interior. 
 ELEMENT ARRAY AND A PROBABILITY OF  THAT A SINGLE SIDELOBE WILL NOT EXCEED 2 4 AT ANY SINGLE LOCATION  IT WILL STILL BE EXPECTED THAT  SIDELOBES WILL EXCEED  24 WHEN ALL  SIDELOBE LOCATIONS ARE TAKEN INTO ACCOUNT &OR VERY LOW SIDELOBE ARRAYS  IT IS REASONABLE TO ALLOW A FEW SIDELOBES TO EXCEED  THE -33, VALUE BY AS MUCH AS  TO  D" TO ACCOUNT FOR RANDOM VARIATIONS 4HIS CAN BE SEEN FROM &IGURE  AS THE DIFFERENCE BETWEEN  0    AND  0     OR 0    )F THIS ALLOWANCE IS NOT GRANTED  THE ANTENNA WILL BE OVERDESIGNED  )T IS WORTHWHILE TO DO SOME PROBABILITY CALCULATIONS BEFORE SPECIFYING THE EXACT SIDELOBE REQUIREMENTS. £Î°Î{  2!$!2 (!.$"//+  £Î°ÈÊ +1 /</" Ê 
 The key premise of the equivalence  principle is that fields from a scatterer (e.g., a reflector) can be represented by an  “equivalent” electric current Jand magnetic current M that are directly related to the  incident E and H fields via  J n H = ×ˆ (12.31)     M n E = − ×ˆ  (12.32) where ˆnis the normal to the reflector surface. The application of the equivalence  principle to PO-based reflector analyses as shown here is a specialized case wherein  the reflector is an electric conductor, and contributions from surface currents on the  backside of the reflector are deemed negligible. An appropriate application of image  theory42–44 imposes a zero tangential E-field (Eq. 
 7.17  Planar Arrays  .....................................................  7.17  Element-Phasing Calculations  ...........................  7.21  7.4 Aperture Matching and Mutual Couplin g  ................ 
 REPORT TIME PER -ARCUMS DEFINITION WHERE THE PROBABILITY IS    THAT AT LEAST ONE FALSE REPORT WILL OCCUR IN THE FALSE 
 Instead, the 6-ft antenna reflector was helically scanned, and targets presented onaPPI whose maximum range was 60,000 yd. Arange ofelevation angles upto10° was covered bythe. 208 THEGATHERING ANDPRESENTATION OFRADAR DATA [~EC. 
   42!#+).' 2!$!2   ° SEPARATED AND COMPARATORS PROVIDED FOR EACH POLARIZATION 4HE SUM AND DIFFERENCE  SIGNALS FROM THE COMPARATORS ARE COMBINED WITH  RELATIVE PHASE TO OBTAIN CIRCULAR POLARIZATION 5SE OF THE PREVIOUSLY DESCRIBED FEEDS FOR CIRCULAR POLARIZATION WOULD REQUIRE THE WAVEGUIDE CIRCUITRY TO BE PROHIBITIVELY COMPLEX #ONSEQUENTLY  A FIVE 
 This allows a  larger anode and cathode structure than with the conventional magnetron, and thererore  a coaxial magnetron can operate at higher power levels. The larger structures permit more  conservative design, with the result that coaxial magnetrons exhibit longer life and better  Output J woveguide  output  Figure 6.3 Cross-sectional sketch  the coaxial cavity magnetron.  194INTRODUCTION TORADAR SYSTEMS (a) (b)Figure 6.2Magnetron resonators. 
 FIELD RANGE CRITERION   2   $ K    WHERE 2 IS THE DISTANCE BETWEEN THE INSTRUMENTATION RADAR AND THE TEST OBJECT AND $ IS  THE MAXIMUM TARGET DIMENSION TRANSVERSE TO THE LINE OF SIGHT !LL OTHER ERROR SOURCES BEING FIXED  COMPLIANCE WITH THE FAR 
 X X-45C low cross section unmanned combat aircraft, 14.42 to 14.43 X band, 1.17 X-Band Radar (XBR), 13.68 to 13.69 ZZ (radar reflectivity factor), 19.4 Z e (effective reflectivity factor), 19.6. 
 In the design of an outdoor test  range, therefore, a decision must be made whether to exploit the ground bounce or to  attempt to defeat it. It is generally easier to exploit it than to eliminate it.FIGURE 14.22  The metal support pylon. The design  is for an incident wave arriving from the left. 
 Delaying theretrans'mission causestherepeated signalstoappearata rangeand/orazimuth different fromthatofthejammer. Thusthesignalfromtherepeater generates afalsetargetechoattheoutputoftheradarreceiver which, inprinciple, cannotbe distinguished fromarealtarget./\.(r1/erereater isonewhichretransmits thesamesignalthata targetwouldreradiate. 1\(rw1sl'0lld('/' repeater playshackastoredreplicaoftheradarsignalafteritistriggered hytheradar.Thetransmitted signalismadetoresemble theradarsignalascloselyas practicable. 
 In addition to open ocean observations, calibrated data from this class of SBR have  been applied to a variety of large-area surface features, such as determination of sea  ice coverage, mapping the boundaries between the principal ice zones of Greenland,  or global estimation of tropical deforestation. In all such applications, the emphasis is  on measurement of mean reflectivity over large areas, rather than mapping fine spatial  detail. These radars typically have resolutions on the scale of 10s of kilometers, sup - ported over swaths of 1000 kilometers or more. 
 ALTITUDE COVERAGE HAVE BEEN MENTIONED 4HE AVAILABLE SPECTRAL WIDTHS ASSIGNED TO RADAR AT 6(& ARE SMALL SO RANGE RESOLUTION IS OFTEN POOR 4HE ANTENNA BEAMWIDTHS ARE USUALLY WIDER THAN AT MICROWAVE FREQUENCIES  SO THERE IS POOR RESOLUTION AND ACCURACY IN ANGLE 4HE 6(& BAND IS CROWDED WITH IMPORTANT CIVILIAN SERVICES SUCH AS 46 AND &- BROADCAST  FURTHER REDUCING THE AVAILABILITY OF SPECTRUM SPACE FOR RADAR %XTERNAL NOISE LEVELS THAT CAN ENTER THE RADAR VIA THE ANTENNA ARE HIGHER AT 6(& THAN AT MICROWAVE FREQUENCIES 0ERHAPS THE CHIEF LIMITATION OF OPERATING RADARS AT 6(& IS THE DIFFICULTY OF OBTAINING SUITABLE SPECTRUM SPACE AT THESE CROWDED FREQUENCIES )N SPITE OF ITS LIMITATIONS  THE 6(& AIR SURVEILLANCE RADAR WAS WIDELY USED BY THE  3OVIET 5NION BECAUSE IT WAS A LARGE COUNTRY  AND THE LOWER COST OF 6(& RADARS MADE THEM ATTRACTIVE FOR PROVIDING AIR SURVEILLANCE OVER THE LARGE EXPANSE OF THAT COUNTRY   4HEY HAVE SAID THEY PRODUCED A LARGE NUMBER OF 6(& AIR 
 Thus the energy within the  pulse must not be too low. If the peak power is limited, a short pulse might not have enough  energy to make clutter, rather than receiver noise, dominate. Pulse compression (Sec. 
 PORAL OR SPATIAL VARIATION IS NOT UNCOMMON  6IBRATION IS ANOTHER CONCERN  ESPECIALLY FOR AIRBORNE AND SPACEBORNE REFLECTORS 2EFLECTORS ON THESE PLATFORMS GENERALLY SEE PARTICULARLY STRESSING VIBRATION LEVELS DRIVEN BY AIRPLANE OR LAUNCH VEHICLE ROCKET  ENVIRONMENTS 0OTENTIAL EXPOSURE TO SALT  SAND  WATER  ETC  IS HIGHLY DEPENDENT UPON PLATFORM  USE OF RADOME OR NOT   ETC  BUT MUST BE CONSIDERED IN THE DESIGN 2ADOMES 2ADOMES ARE USED WHEN IT IS NECESSARY TO PROTECT ANTENNAS FROM  ADVERSE ENVIRONMENTAL EFFECTS )DEALLY  A RADOME SHOULD BE PERFECTLY TRANSPARENT TO THE 2& RADIATION FROM OR TO  THE ANTENNA AND YET BE ABLE TO WITHSTAND SUCH ENVIRONMENTAL EFFECTS AS WIND  RAIN  HAIL  SNOW  ICE  SAND  SALT SPRAY  LIGHTNING  AND IN THE CASE OF HIGH 
 Moreover, the mainlobe of C was widened and a ﬀected by the sidelobes of B. $]LPXWK P (OHYDWLRQ P         h    (a) ( b)      $]LPXWK P $PSOLWXGH G%   3URSRVHG 0HWKRG 5HFWDQJXODU:LQGRZaρ      $]LPXWK P $PSOLWXGH G%   3URSRVHG 0HWKRG 7D\ORU :LQGRZ aρ   (c) ( d) 5DQJH P $]LPXWK P     Figure 5. Imaging results for a point target. 
 Switched Clamps.—In agreat many appli- cations theclamp must beopened and closed over particular time intervals which may or may not bedirectly related tothe signals. According towhether theclamp can conduct inone orboth directions when c1osed itis classified asaone-way-(” single-sided”) ora two-way (”double-sided”) clamp. Inthediagrams, E,isthepotential ofthe clamping point, Xisthepoint being clam~ed,/lA-&,.o ~!?~oFIG, 13.22.—Bottom clip- per (biased diode ‘:pick-off” circuit). 
 FIG. 10.6 Surface-wave delay line. WRVEFORM DURRTION (|js) FIG. 
 Acquisition depends on the direction of arrival (DoA), operating band,  carrier frequency, pulse width, PRI, scan rate, and other parameters of the victim radar.  An ARM homes on the continuous radiation from the radar sidelobes or on the flash of  energy from the main beam. ARM benefits from the one-way-only radar signal attenua - tion. 
 The measuring object of interest is represented in block 3, where the transmitting and  receiving paths are shown respectively in block 2 and 4.  In th e available case the system is  polarimetrically constructed with two linear, orthogonal polarizations.  This will be maintained  in the following without restriction of the general validity, since any other arbitrary orthogonal  polarization can be derived f rom it. 
 MENT FACTOR OBTAINABLE WITH A SCANNING 
 The figure is a plot of g  rather than s 0 (g = s 0/cos q).   At low frequencies such as VHF, this condition changes because the attenuation through  the leaves and branches is less.137 Soil Moisture.  Figure 16.32 shows the size of the effect of soil moisture on s 0. 
 (The group velocity is the velocity with which  energy is propagated along the slow-wave circuit, and the phase velocity is the velocity of the  RF signal on the slow-wave circuit as it appears to the electrons. To achieve RF  Energy Charging  impedance  ( ___ .,._ __  t  I Energy  storage  element  Load  Figure 6.12 Sim pie representation of a  crossed-field amplifier. (From Clam­ pitt,6 Electronic Progress, Raytliein.) . 
 IlFradarequation. ThesimpleOTHradarequation ofEq.(14.22)doesnotaccount forthe factthatasurveillance radarmustcoveraspecified angular sectorinaspecified time.The radarequation foramicrowave surveillance radarwasgivenbyEq.(2.57).Thismustbe modified foranHFradarsincethecoherent integration timeT.:isfixedinanHFradarbythe doppler processing requirements. AlsoinanHFradar,theelevation beamwidth Orisoftennot available asadesignparameter becauseofthelargecostofhighantenna structures. 
 Multifeed designs use combining networks to generate differential  feed distributions. In its simplest form, an (az/el) multifeed monopulse feed array  can be realized as a four-element feed, as shown in Figure 12.28. However, some  applications use more feed elements to further tailor the distribution to improve  efficiency and/or difference beam slope. 
 Williams, “Civil marine radar—a fresh look at transmitter spectral control and diversity  operation,” The Journal of Navigation , vol. 55, pp 405–418, 2002. 21. 
 (8.2 1) is satisfied; else multiple  beams, or grating lobes, will appear. It can be shown that if an array radiates at a particular  angle corresponding to a value m in Eq. (8.17b) when the frequency isf, then for some other  \alile itr, a beam will be radiated at the same angle when the frequency is f, = (t~, /rrr)f. 
 TAP EXAMPLE&)'52%   'ENERAL ))2 FILTER BLOCK DIAGRAM            &)'52%    4RANSPOSED  FORM  &)2 FILTER       . Óx°Ón  2!$!2 (!.$"//+  $ECIMATION &ILTERS  !S MENTIONED PREVIOUSLY  THE COMPLEXITY AND COST OF A SIGNAL  PROCESSOR  IN TERMS OF THE AMOUNT OF SYSTEM RESOURCES REQUIRED TO IMPLEMENT IT  GENER 
 Sandretto, P. C.: The Long Quest, IRE Trans., vol. ANE-1, no. 
 4305^315, September 1977. 69. Zhou Zheng-Ou, et al.: A Bistatic Radar for Geological Probing, Microwave J., pp. 
  FORWARD SCATTER FENCE n AND THE &RENCH  'RAVES FOR SPACE SURVEILLANCE  WERE LATER DEVELOPMENTS /MITTED ENTRIES IN THE DEDICATED TRANSMITTER COLUMN FOR OPERATION IN THE RECEIVER 
 3  STRIKE IS SHOWN IN &IGURE  4HE MISSION PROFILE BEGINS WITH A TAKEOFF  CON 
 HALF WAVELENGTH BECAUSE OF THE TWO 
 Frequencies above S band are better for information gathering, such as high-data- rate precision tracking and the recognition of individual targets. If a single fre- . quency must be used for both air surveillance and precision tracking, as in mili- tary air defense systems based on phased array multifunction radar, a suitable compromise might be S band. 
 NITROGEN  RATIO  CLAY MINERALOGY  SOIL DEPTH  SOIL MOISTURE CAPACITY  AND SOIL DRAINAGE CLASS 3UCH INFORMATION IS USEFUL IN ASSESSING THE POTENTIAL OF 2& TECHNIQUES AND PARTICULARLY '02 FOR PARTICULAR GEO 
 Upton, “An ultralow-sidelobe  adaptive array antenna,” The Lincoln Laboratory Journal , vol. 3, no. 2, pp. 
 85. K. Hasselmann, D. 
 Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.40  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Because volume scatter dominates for dense vegetation, especially trees, s 0 is  nearly independent of the angle of incidence. Figure 16.35136 shows this with results  from X-band imaging of a forest. 
  ", 
 Air Data Links.  The MFAR is part of a network of sensors and informa - tion sources (C3ISR net) sometimes called the Global Information Grid (GIG) .   A major use of radar and aircraft data links is to provide total situational awareness.21   By using on-board and off-board sensor fusion, a total air and ground picture  can be presented in the cockpit. 
 SIGNAL OR MINIMUM 
 ELEMENT PHASE SHIFT IN THE X DIRECTION  4YS   OK DY COS @YS   ELEMENT 
 Sensors 2019 ,19, 252 prototypes. The ﬁeld test conducted with the SPARX prototype showed that the MIMO imaging works effectively in detecting and identifying various target distributed inside the scenario. However, it should be remarked that to obtain an azimuth resolution comparable to standard mechanical systems, a large number of modules is needed, thus greatly increasing the cost and complexity of the system. 
 TO 
 Notalliong-duration screensneedbecascade. TheP19isasingle-component phosphor withlongpersistence andnoflash.Ifextremely longpersistence isdesiredinacathode-ray-tube display,astoragetubemaybeused.Forallpractical purposes, animageplacedonastorage tubewillremainindefinitely untilerased. Table9.1RadarCRTphosphor characteristics (afterBerg26) Phosphor Fluorescent color Phosphorescent color Persistence· PI Yellowish green Yellowish green Medium P7 Blue Yellowish green Blue,medium short; yellow,long P12 Orange Orange Long Pl3 Reddish orange Reddishorange Medium Pl4 Purplishbbe Yellowish orange Blue,medium short; yellowish orange,medium Pl7 Blue Yellow Blue,short;yellow,long Pl9 Orange Orange Long P21 Reddish orange Reddish orange Medium P25 Orange Orange Medium P26 Orange Orange Verylong P28 Yellowish green Yellowish green Long P32 Purplish blue Yellowish green Long P33 Orange Orange Verylong P34 Bluishgreen Yellowish green Verylong P38 Orange Orange Verylong P39 Yellowish green Yellowish green Long •Persistence to10percent level:short=1to10Jls;medium short=10Jlsto1ms; medium=1to100ms;long=100msto1s;verylong=>1s.. 
 However, the  basic signal processing of amplitude- and  phase-comparison monopulse is similar,  but the control of amplitude distribution across an array aperture for the sum and   difference signals maintains efficiency and lower sidelobes. Figure 9.10 shows the antenna and receiver for one angular-coordinate tracking by  phase comparison monopulse. Any phase shifts occurring in the mixer and IF ampli - fier stages causes a shift in the boresight of the system. 
 The peak loss is considerable under the scintillation, which will reduce the visibility of weak scatters and the contrast of SAR images. The experiment results also demonstrate that the scintillation effect is less serious in the case of CkL≤1032and p≤2 and this can be considered to be a threshold to evaluate the inﬂuence of scintillation effect on space-borne P-band SAR system. Another group of Monte-Carlo simulations are carried out to make a comparison between stripmap mode and sliding spotlight mode as is shown in Table 3. 
 The fundamental accuracy of the sequential-lobing technique for a scanning beam generated by a uniformly illuminated aperture on transmit and receive is presented in Fig. 20.4a. Performance is presented in terms of a normalized ver- *The signal-to-noise-ratio definition used here is EiN0, where E is the received pulse energy and N0/2 is the spectral power density of the interfering thermal noise. 
 arc at  anode potential. Electrons arc not intentionally collected by the anode as in other tubes:  instead, the electrons are removed by the collector electrode (shown on the right-hand side of  the diagram) after the beam has given up its RF energy to the output cavity.  The input signal is applied across the interaction gap of the first cavity. 
 TO 
 STATE TRANSMITTERS IS THE ACTIVE APERTURE PHASED  ARRAY RADAR !T EACH ELEMENT OF A PHASED ARRAY RADAR ANTENNA IS A SOLID 
 The higher thermal conductivity of SiC enables more efficient thermal manage - ment. Coupled with the high breakdown voltage and channel current capability of the  SiC MESFET, measured results of 80 watts of CW power output with an 8 dB associ - ated level of large signal gain at 3.1 GHz from a 58 V drain supply voltage have been  reported24 from a single transistor cell. Electron mobility in the GaN HEMT at saturated drift velocities is high enough that  high gain with simultaneous high power output and high efficiencies can be achieved  with voltages as low as 20 to 30 volts. 
 Mason, S. J., and H. J. 
 Alternative Methods for Obtaining Coherence.—Figures 16% and 16.9 show two clifferent ways ofproducing coherence between echo signals and areference signal: inthe first method, the oscillator whose phase islocked runs atradio frequency and the signals are added at radio frequency; inthesecond, thelocking and adding areboth done at theintermediate frequency. Mcdulator Transmitter TR I Iv I I MixerStablelocalMixer oscillator Locking Echosignals Coherent l-f oscillatorReceiver Reference signal (a)t MdulatorPower— TRamplifier t $ 1 If— Mixer —Stablelocal transmitter oscillator i I ICoherent l-fReferencet LockingReceiver oscillator signal Echosignals (b) t FIG. 16.13.—I-f locking, i-f addition. 
 Guerlac’s history. 1Here itwill besufficient toreport the earliest full successes. Inearly 1939, aradar setdesigned and built atthe Naval Research Laboratory was given exhaustive tests atseaduring battle maneuvers, installed onthe U.S.S.NewYork. 
 NOISE MATCHED FIL 
 ch01.indd   5 11/30/07   4:33:39 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 
 /XIDE 
 Two  range gates are generated as shown in Fig. 5.17. One is the early gate, and the other is the late  gate. 
 One of the chief reasons for employing automatic detection is to overcome the  limitations of an operator due to fatigue, boredom, and overload. In addition, the use of  automatic detection allows the radar output to be transmitted over telephone lines rather than  by more expensive broadband microwave links, since only detected target information need be  transmitted and not the full bandwidth signal (raw video). Automatic detection is also an  important part of automatic detection and track (ADT) systems, as discussed in Sec. 
 METRICAL SINE 
 Thephaseshiftforproperoperation whenpropagating inthereversedirection isobtained by simplyreversing thepolarity ofthedrivepulses.Thisreverses thedirection ofmagnetization of thefcrritetoroid,whichisequivalent toreversing thedircction ofpropagalion. NOIlrl:ciprocal phaseshifterscannotbell-;~dinreflectarrays (Sec.g.6),sincetheelectromagnetic energyll1ust travelinbothdirections. Theiruseisalsonotpractical inshort-range radarorwithhigh-duty cyclewaveforms likethoseusedinsomepulse-doppler radars,sincctheswitching hetwecn the twostatesistooslow. 
 4141, 1953.  40. Jackson, J., and E. 
 IEEE T rans. Geosci. Remote. 
 A typical rain spectrum with a nonzero average velocity is  depicted on the bottom line. (Precipitation at S band might typically have a spectral width of  about 25 to 30 knots centered anywhere from -60 to +60 knots, depending on the wind  coriditiotis and tlie antenna pointing.42) Tlie narrow spectrutn of tile nioving aircraft is at the  right of the figure. Because of foldover it is shown as occupying filters 6 and 7 on prf-I, and  filters 7 and 8 on prf-2. 
   PP n  *ULY   * , !LLEN  h/N ARRAY ELEMENT IMPEDANCE VARIATION WITH SPACING v  )%%% 4RANS  VOL !0 
 Reﬁnement and Re-ﬂattening After phase unwrapping, 46 Ground Control Points (GCPs) are selected to correct the unwrapped phase. The selection criteria are as follows: (1) the location has a high coherence value and good phase unwrapping, (2) land deformation is close to zero according to previous studies and leveling data, and (3) we should select as many GCPs as possible. 3.4. 
 M.: "Monopulse Principles and Techniques," Artech House, Norwood, Mass., 1985, chap. 5, chap. 12, pp. 
 Three association gates are constructed around the  predicted positions of three existing tracks. Three detections are made, but assignment of  the detections to the tracks is not obvious: two detections are within gate 1; three detec - tions are within gate 2; and one detection is within gate 3. Table 7.6 lists all detections  FIGURE 7.32  Examples of the problems caused by multiple detections and  tracks in close vicinity ( from G. 
 For this reason, height finders which use electronic scan usually radiate penci  beams rather than broad fan beams.  V-beam radar. This radar generates two fan beams: one vertical and the otl~cr slanted at some  angle to the vertical (perhaps at 30 to 45'). 
 568INTRODUCTION TORADAR SYSTEMS 43.McAulay, R.J.:Interferometer DesignforElevation AngleEstimation, IEEETrl/II.\.•vol.AI·S·I pp.4g6-503, September, 1977. 44.Potter,K.E.:Experimental DesignStudyofanAirborne Interferometer forTerrain AvoiJam:c. Intel"llational COt!(t'I"t'nCL' RADAR-n, pp.50g512,JEE (London) ConLPllbl. 
 Hughes24) FIGURE 7.17  Curves of probability of detection versus signal-to-noise ratio for the cell-   averaging CFAR, ratio detectors, log integrator, and binary integrator: Rayleigh, pulse-to-pulse  fluctuations, 2 m = 16 reference cells, Pfa = 10−6, and maximum jamming-to-noise ratio = 20 dB  (from G. V . Trunk and P . 
 RELATED SYMBOLS  TERMS AND ABBREVIATIONS v 3AFETY  OF .AVIGATION #IRCULAR   )NTERNATIONAL -ARITIME /RGANIZATION  ,ONDON    h0ERFORMANCE STANDARDS FOR THE PRESENTATION OF NAVIGATION 
 W., Jr., and G. Brunins: Long-Range Surveillance Radars for Automatic Control Systems,  Record of the IEEE 1975 International Radar Conference, pp. 312-317. 
 A CFAR may be obtained by observing the noise or clutter background in the viciniLy of  the target and adjusting the threshold in accordance with the measured background. Figure  10.11 illustrates the cell-averaging CF AR which utilizes a tapped deL1y-line to sample the  range cells to either side of the range cell of interest, or test cell. T11e output of the test cell is the  radar output. 
 Britt: Phantom Radar Targets at Millimeter Radio  Wavelengths. I RE Trans .. vol. 
 4.6 has had wide application.  4.2 DELAY-LINE CANCELERS  The simple MTI delay-line canceler shown in Fig. 4.4 is an example of a time-domain filter. 
 2. Waveform gen- eration by digi- tal means most popular.1 . Widely used in past. 
 2.8b, where integration loss in decibels  is defined as Li(n) = 10 log [l/Ei(n)]. The integration-improvement factor (or the integration  loss) is not a sensitive function of either the probability of detection or the probability of false  alarm.  The parameter n, for the curves of Fig. 
 The picture on the tube with Type B is, first, of a  square of faint light. Somewhere in this square you may  detect one or two brighter spots of light, indicating  echoes received from aircraft ahead. This square is thus  a graph, or a distorted map. 
 S. Puckle’s Time Bases or Sir Robert Watson-  Watt’s Applications of the Cathode Ray Oseillograph in  Radio Research.  Typical of the hard-valve time-base generators is that  used in the Cossor Model 339 double-beam oscillograph,  and a detailed description will be given of this, as it is  quite simple to follow and shows how the standard hard-  . 
 TOR ANTENNAS WERE ONCE THE DOMINANT ANTENNA DESIGN CHOICE FOR MEDIUM 
 The day-night cycle produces drastic changes in the ion - ization distribution within the ionosphere. At night, the D-layer disappears, the E and  F regions experience a substantial decrease in ionization, and the equatorial and polar  regions are more prone to large-scale perturbations. The extent of diurnal variation can  be seen by examining Figure 20.4, which shows measured electron density (expressed  in terms of plasma frequency as defined in Eq. 
 7 +IM    3 7DOWINSKI  AND $ 7HITMAN  h3PACE GEODESY 3UBSIDENCE AND FLOODING IN .EW /RLEANS v  .ATURE  VOL   PP n    $ 'HIGLIA AND - 0RITT   4WO 
 F~xed parohl~c  reflector  w~th porollel  wires  \  L-- , .  ' '- AXIS of mlrror movement  Figure 7.13 Geometry of the polarization-  * ,Y.;,~\ Movable twist nrirror-scan antenna, using a polar- , - --plonar  twist reflector ization-sensitive parabolic reflector and a  planar polarization-rotating twist reflector.  \ Scanning of the beam is accomplished by  mechanical motion of the planar twist-  reflector. 
 Puhl. no. 155. 
 J. Phillips, L. Marinangeli, G. 
 Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 23.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 REFERENCES  1. N. 
 Not unnaturally, cost, for a given performance, is the prime driver in the system  designer’s choice of antenna. While the conventional slotted linear array is widely  used, there are examples where different cost tradeoffs have been made. For instance,  the use of a dielectric block mounted directly in front of the slotted waveguide array,  in place of the flared section, has been used as an alternative. 
 Height-finding radars which measure . 446 INTRODUCTION TO RADAR SYSTEMS  elevation angle of arrival by comparing the amplitudes of the signals received at two different  beam ekvation angles (lobe comparison) qrn give erroneous and ambiguous measurements al  low angles.4· 75 Elevation errors near the ground may be considerably reduced in magnitude  and the ambiguities eliminated by surrounding the radar with a metallic fence to remove the  ground-reflected wave. The fence replaces the gr0tind-rdlccted wave with a diffracted wave of  lesser importance. 
 Whenθ=θi(i=1, 2, ..., N), the sequence DEMs are taken from the DEM image. This sequence stores the DEM data in the DEM image at θ=θi. Its size is M×1. 
 Inaddition tothevertical fanbeam which ischar- acteristic ofmicrowave search radar (cf. Chap. 15), the V-beam set provides anadditional fan beam that isrotating atthe same speed and theplane ofwhich istilted outofthevertical. 
 The reduction of transmit antenna gain in a  multiple-beam radar is compensated, however, in the ideal case by the increased number of  hits available for integration. The gain of the transmitting antenna in the multiple-beam  system is 0,/0, = I/ N that of the transmitting gain of the scanning-beam antenna. Thus the  signal-to-noise ratio per pulse of the multiple-beam radar is less than the signal-to-noise ratio  of the scanning-beam radar. 
 However, since the main beam is virtually unchanged, about 90 percent of the power is delivered to the sidelobe region. If the removed elements (in a regular thinned array) are replaced with ele- ments with matched loads, the element pattern is identical to that of one in the regular array with all elements excited. The element pattern is independent of the array excitation, and the same fractional amount of power will be lost (because of mismatch) whether the array is thinned, tapered, or uniformly illuminated. 
 Thelineararraygenerates afanbeamwhenthephaserelationships aresuchthatthe radiation isperpendicular tothearray.Whentheradiation isatsomeangleotherthan ,. broadside. theradiation pattern isaconical-shaped beam.Thebroadside linear-array antenna maybeusedwherebroadcoverage inoneplaneandnarrowbeamwidth intheorthogonal planearedesired. 
 Saturation results in the virtual elimination of information about targets. Wide dynamic range (i.e., log and lin-log) receivers are normally used to avoid saturation. Other special processing circuits can be used in the radar to avoid saturation, i.e., fast-time-constant (FTC) devices, automatic gain control (AGC), and constant-false-alarm rate (CFAR).3'15'17 However, they cannot be said to be ECCM techniques. 
 DOPPLER DETECTION BECAUSE THE TRACK STATE 
 The silicon Laterally Diffused Metal-Oxide Semi-   conductor (LDMOS) transistor is beginning to supersede the silicon power BJT as  a replacement device, especially at the VHF, UHF, and L-band frequencies. In par - ticular, the commercial communications industry has found that the Si LDMOS FET  dominates as a cell phone base-station power amplifier because of the higher gain,  linearity, and efficiency that it demonstrates compared to the silicon BJT. Although it  is a FET, its construction characteristics, packaging, and design challenges are very  similar to the design challenges of the Si BJT.FIGURE 11.6  A 230-watt L-band long-pulse and high-duty- cycle silicon bipolar power transistor in a custom hermetic,  dual-leaded, low-inductance package has an overall footprint of  0.40" × 0.45." ( Photograph courtesy of Raytheon Company ) ch11.indd   11 12/17/07   2:25:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The sur- face is considered smooth, target and antenna heights are 2 m, conduc- tivity is assumed to be 5 S/m, and the dielectric constant is 80. (A2/47r) (L6)2 LOSS(dB) GT AND GR INCLUDE PERFECT EARTH a IS FREE-SPACE CROSS SECTION . surface reflection when radar and target are above the horizon and illumination in the penumbra and shadow region by a surface-attached wave. 
 2006 ,3, 457–461. [ CrossRef ] 12. Yousif, O.; Ban, Y. 
 Themethod oflocating thetargetposition issimilarineitherradar.Bothrequirethe measurement ofadistance andtheangleofarrivalintwoorthogonal angular coordinates. The distancc measured bythebistatic radaristhesumS=D,+Dr.thetotalscattered path. ThesumD,+Drlocatesthetargetsomewhere onthesurfaceofaprolatespheroid (anellipse rotatedaboutitsmajoraxis)whosetwofociareatthelocation ofthetransmitter andreceiver. 
 The principal disadvantage ofusing synchros toprovide torque is that power must betransmitted bythe primary s.vnchro. This limits thenumber ofrepeaters which can beused. Further, insystems with more than one repeater, anerror inany tends tothrow the system off balance and toaffect theaccuracy ofother repeaters. 
 The simulation result shows that the aspect entropy is more accurate in high signal-to-noise ratio. Only high scatterings in the RCS curve is important on anisotropic target discrimination. Therefore, we proposed a RCS curve denoising method and it is shown effective by the simulation. 
   
 25 STAP block diagram: element space pre-doppler element space architecture ch03.indd   27 12/15/07   6:03:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 
 DIGITAL CONVERTER SURVEY AND ANALYSIS v  )%%% *OURNAL ON 3ELECTED !REAS  IN #OMMUNICATIONS  VOL   NO   PP n  !PRIL   " "RANNON  h3AMPLED SYSTEMS AND THE EFFECTS OF CLOCK PHASE NOISE AND JITTER v !NALOG $EVICES  )NC  !PPLICATION .OTE  !. 
 The microwave radar that uses the over-ocean evaporative duct (Sec. 12.5) to obtain  extended propagation to detect low-altitude or surface targets beyond the normal line of sight  is also sometimes called an over-the-horizon radar. It should not be confused with the HF  radars described in this section that operate at much lower frequencies and at much longer  ranges. 
 DOPPLER IMAGE OF A SHIP WITH  RANGE BINS IS SYNTHESIZED AS AN EXAMPLE IN 0ACE ET AL  %##- TECHNIQUES TO  DEFEAT THIS TYPE OF JAMMING SIGNALS ARE SIMILAR TO THOSE PROPOSED FOR 3!2 /VER 
 For example, db has been changed to dB, and Mc is replaced by Mi i~. Also, t he  letter-band nomenclature widely employed by the radar engineer for designating the common  radar frequency bands (such as L, S, and X) has been officially adopted as a standard by the  IEEE.  The material in this book has been used as the basis for a graduate course in radar taught  by the author at the Johns Hopkins .University Evening College and, before that, at several  other institutions. 
 to IEEE Int. Radar Conf. Rec ., May 6–9,  1985, pp. 
 BAND FREQUENCIES    !LTHOUGH THERE IS NO ASSURANCE THAT  &)'52%   'ENERAL TRENDS IN CLUTTER BEHAVIOR FOR AVERAGE  WIND SPEEDS ABOUT  KT  BASED ON .2, &2 DATA 0LOTS REPRESENT  , 
 This process of impressing a time variation  in velocity that results in bunching of the electrons of an initially uniform electron  beam is called velocity modulation . Three or more RF cavities might be used. The  interaction gap of the output cavity is placed at the point of maximum bunching so  that the RF power can be extracted from the density modulated electron beam by a  coupling loop in a lower power tube or by a waveguide (not shown) in a high power  tube. 
 BURST WAVEFORM !S THE TARGET FOLLOWS A PARTICULAR TRA 
 Figure 1.2 Block diagram of a pulse radar.  THENATURE OFRADARS 1.3RADAR BLOCK DIAGRAM ANDOPERATION Theoperation ofatypicalpulseradarmaybedescribed withtheaidoftheblockdiagram showninFig.1.2.Thetransmitter maybeanoscillator. suchasamagnetron. 
 SCAN IS ESSENTIALLY AN  X  Y PLANE AT A SELECTED VALUE OF  : OR RANGE OF  VALUES OF :  MANY OF THE PROCESSES DESCRIBED IN THE PREVIOUS SECTION CAN BE APPLIED&)'52%   " 
 The installation in a Wellington Mk. VIII is shown in ﬁgure 2.22. Tests were made against a radar receiver on the ground and an approximately constant signal strength could be maintained at the receiver as the radar approached. 
 3TATE !IR 4RAFFIC #ONTROL 2ADAR   4HE !32 
 ESIS MODELS 5NLIKE TRADITIONAL TRACKING FILTERS SUCH AS THE +ALMAN FILTER  WHICH SELECTS  A SINGLE DETECTION IE  PEAK OR PLOT  TO ASSOCIATE WITH EACH MAINTAINED TRACK  0$! FILTERS COMBINE THE INFLUENCE OF ALL THE CANDIDATE PEAKS WITHIN A PRESCRIBED RADIUS TO COMPUTE A TRACK UPDATE )N THE SKYWAVE RADAR CONTEXT  THIS HAS YIELDED SUPERIOR RESULTS !N IMPORTANT DECISION RELATES TO WHERE THE COORDINATE REGISTRATION IS IMPLEMENTED  3OME SYSTEMS ESTABLISH TRACKS IN RADAR COORDINATES AND THEN PASS THE TRACKS  INCLUDING MULTIPLE TRACKS FROM A SINGLE TARGET  TO THE #2 SYSTEM  WHICH MUST IDENTIFY AND RECON 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 8.42  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8  9. 
 STATE VALUE  BUT FOR AN OPERATING PULSE WIDTH REPRESENTATIVE OF  A SHORTER RANGE FIRE CONTROL RADAR ^ §S   THE  TEMPERATURE RISE ACROSS THE SILICON DIE  HAS ONLY REACHED  OF ITS STEADY 
 820–821, November 1967. 77. J. 
 1000 ft on a small fighter aircraft at 100 nmi is claimed by the radar manufacturer. A solid-state transmitter version of the radar, the S273 with a shorter and wider array, is also available. This version offers a six- or eight-beam stack, with a 1.4° azimuth beamwidth but with wider beams in elevation covering to 20° total ele- vation. 
 C. L. Temes, “Sidelobe suppression in a range channel pulse-compression radar,” IRE Trans .,   vol. 
 , vol. 85, pp. 1045–1049, 1980. 
 Alternatively, for the  quadratic case  R R a t tk kt kft po = + −1 202( )  (24.13) where apo is the pull-off acceleration. Radar Scheduling.  The scheduling and the tracking functions closely cooper - ate; both interact to update, with current measurements, the target’s state vector, and  make the predictions necessary to point the radar beam at the target the next time it  is observed, select the type of waveform to radiate, and select the threshold to apply  for target detection. 
 H., and D. D. Howard: Target Noise, chap. 
 Equation (8.6) is only an approximation, which may be seriously inadequate for many  problems of array design. It should be used with caution. It ignores mutual coupling, and it  does not take account of the scattering or diffraction of radiation by the adjacent array  elements or of the outward-traveling-wave coupling. 
 Asthe aircraft moves, these dials will continue to read the correct position ofthe target relative tothe aircraft and the. 218 THEEMPLOYMENT OFRADARDATA [SEC. 73 index will continue tostay onthetarget echo, provided that the correct value ofwind has been setinto thedevice bymeans ofthetwo “wind” knobs shown. 
 RGHPRF produces the longest  detection range against closing low cross section targets.71 Ultra-low noise frequency  references are required to improve subclutter visibility on low RCS targets even using  STAP. Range gating dramatically improves sidelobe clutter rejection, which allows  operation at lower ownship altitudes. Principal limitations of RGHPRF closing target  detection performance are eclipsing (a radar return when the receiver is off during the  transmitted pulse) and range gate straddle losses (the range gate sampling time misses  the peak of the radar return).15 Figure 5.18 shows TPi with eclipsing and straddle losses  near maximum range for a high performance RGHPRF. 
 FORMAL ARRAYS. £Î°{  2!$!2 (!.$"//+  $ 6OLUMETRIC 3EARCH  4HREE 
 Optical Techniques. The optical techniques involve the recording of the radar signals on a transparency, most frequently silver halide photographic film in any of a number of formats. Initially the successive range sweeps were placed parallel and side by side; later polar format was used. 
 13. Lavallee, L. R.: Two-Phased Transistors Shortchange Class-C Amps, Microwaves, pp. 
 174 long signals from straddling two ormore pulse intervals and thus provid- ing false coincidences. Itcannot, ofcourse, prevent such blocks of signals from saturating thereceiver and excludlng the desired pulses. Abrief analysis ofthe effectiveness ofthe coding isworth while. 
  
 D., M. B. Thomas, and G. 
 Thus it is  essential that noise be prevented from entering the receiver via the antenna sidelobes.  A jammer whose noise energy is concentrated within tile radar receiver bandwidth is  called a spot jammer. The spot jammer can be a potent threat to the radar if it is allowed to  concentrate large power entirely within the radar bandwidth. 
 S.: Digital Signal Processing, chap. 35 of" Radar Handbook," M. l. 
 determined by the illitmination of the line source, while tlie heamwidtll ill tlic perpendici~lar  plane is determined by the illumination across the parabolic profile. TIie refiector is made  longer than the linear feed to avoid spillover and diffraction effects. One of tlie advantages of'  the parabolic cylinder is that it can readily generate an asymmetrical fan beam with a ~nuch  larger aspect ratio (length to width) than can a section of a paraboloid. 
 Other resonances occur near odd multiples of a quarter wavelength, with plateaus of nearly constant re- j0/x FIG. 11.7 Measured broadside returns of a thin dipole. (Courtesy of University of Michigan Radiation Laboratory.6)RELATIVEPOWER (dB) . 
 Radar, Sonar,  and Navigation , vol. 143, pp. 53–63, February 1996. 
 I>ilty cycles of the ordcr of 0.1 arc not ilnusual, whicli is sig~iificaritly  greater tli;iri tlie duty cycles typical of riiicrowave tubes. The high duty cycles present special  constrairits or1 ~llc raclar systetli dcsigller so that solid-state transtnitters are not inter-  cliangeable with tube trans~ltitters. A difierent system design philosophy usually must be  cmployed with solid state. 
 van Zyl, “Unsupervised classification of scattering behavior using radar polarimetry data,”  IEEE Trans. Geosc. Rem. 
 An example of the use of these filter characteristics applied to  the design of a delay-line periodic filter is given in either of White's Consider the  frequency-response characteristic of a three-pole Chebyshev low-pass filter having 0.5 dB  ripple in the passband (Fig. 4.14). The three different delay-line-filter frequency-response char-  acteristics shown in Fig. 
 D.: Target Clutter, and Noise Spectra, pt VI, chap. I of "Modern Radar," R. S. 
 Michaels: Radar Observations  of Insects in Free Flight. Science. vol. 
 It is likely that the iono- sphere will vary across the 64° azimuth scan, so that if a single operating fre- quency is used, the range to the transmitter footprint will change with azimuth; however, in general a different operating frequency could be selected for each 8° to obtain the desired illumination. Each transmitter footprint is filled by 16 con- tiguous receive beams, each 1A0 wide. At the lower left, one illumination sector is shown divided into receive resolution cells with each cell being approximately 10 nmi on the side. 
 The given definition applies for the general bistatic case  € θi,φi,θS,φSarbitrary ( ). In practice  receiving and sending antennas are often identical, meaning  € θi=θS and  € φi=φS. σ can then be  referred to as Radar Backscattering Cross- Section, the Radar geometry being monostatic. 
 RADAR OUTPUT IS USED TO MEASURE THE  TRAJECTORY OF THE MISSILE AND TO PREDICT FUTURE POSITION 4RACKING RADARS ARE USED TO COM 
 Ulaby, “A reexamination of soil textural effects on micro - wave emission and backscattering,” IEEE Trans. , vol. GE-22, pp. 
 BOARD #LOUD3AT HAS  M VERTICAL RESOLUTION WITH A  KM FOOTPRINT AND IS SIMILAR TO  THE .!3! !IRBORNE #LOUD 2ADA R THAT HAS FLOWN FOR  SEVERAL YEARS ON BOARD THE .!3! $# 
 The amount of noise  reduction may be estimated by comparing the area under a spectral-power-density plot  of angle noise below the frequency corresponding to the radar servo bandwidth with  the total area under the power-density plot. (The spectral-power-density plot may be  obtained by squaring the ordinate values of a spectral-distribution plot such as shown  in Figure 9.23). The choice of AGC characteristics also affects the amount of angle noise followed  by a tracking antenna. 
 and P. P. Batlivala: Diurnal Variations of Radar Backscatter from a Vegetation Canopy,  IEEE Trans., vol. 
 Bistatic RCS Region.  The bistatic angle at which the equivalence theorem fails  to predict the bistatic RCS identifies the start of the second bistatic region. In this  region, the bistatic RCS diverges from the monostatic RCS. 
 A variety of low-noise radar receivers are available to the radar system designer. The  well-recognized benefits of low-noise receivers, combined with their relative affordability,  make them an attractive feature in modern radar design. However, low-noise receivers are  ~ornetinies accompanied by otlier less desirable properties that tend to result in a compromise  irl receiver perforr~iance. 
 Barker, R. H.: Group Synchronization of Binary Digital Systems, in Jackson, W. (ed.): "Communication Theory," Academic Press, New York, 1953, pp. 
 72. Blomfield, D. L. 
 It is essential that the measured data be defined as SSB or DSB, since there is a 3 dB difference in the two forms of data. Range Dependence. Most modern radars use the stalo to generate the trans- mitted pulse as well as to shift the frequency of the received echoes. 
 Ward, “Signal-to-noise ratio loss in moving target indicator,” Proc. IEEE ,  vol. 56, pp. 
 SEC.1.4] THEPERFORMANCE OFRADAR 11 thebeam passing through anaperture ofgiven size depends ontheratio ofthediameter ofthe aperture tothewavelength oftheradiation inthe beam, the sharpness ofthe beam produced byaradar antenna (which can bethought ofasasort ofaperture fortheradio energy) depends on the ratio ofthe antenna dimensions tothe wavelength used. For an antenna ofgiven size, thebreadth ofthebeam produced isproportional tothewavelength. These statements aremade precise inSec. 
 ERS  WIDEBAND AMPLIFIERS  PHASE SHIFTERS  ATTENUATORS  42 SWITCHES  AND OTHER SPECIAL FUNCTION DESIGNS .OTEWORTHY DESIGN CONSIDERATIONS FOR THESE --)# FUNCTIONS ARE DESCRIBED NEXT&)'52%    #OMMON 42 MODULE CONFIGURATIONS MAKE USE OF POWER  AMPLIFIERS  LOW 
 1/2, pp. 11-29, January/February, 1976.  80. 
 71.King,R.J.:"Microwave Homodyne Systems," PeterPeregrinus Ltd.,Stevenage, Herts,England, 1971:l (anInst.Elect.Engs.publ.). 72.B1omfield, D.L.H.:Low-Noise Microwave Sources, International CO'1ference onRadar-Present arul Future,Oct.23-25,1973,lEE(London) Puhl.no.105,pp.178-183. 73.Ashley,1.R.,T.A.Barley,andG.J.Rast,Jr.:TheMeasurement ofNoiseinMicrowave Transmitters, IEEETrans.,vol.MTT-25, pp.294-318, April,1977.. 
 186-199, 1957.  3. Capon, J.: Optimum Weighting Functions for the Detection of Sampled Signals in Noise, IEEE  Trans., vol. 
 13.3 General Sea Descriptors  ....................................  13.5 . This page has been reformatted by Knovel to provide easier navigation. 
 As with ship classiﬁcation, many issues may arise when training CNNs. One common issue is over-ﬁtting. Over-ﬁtting can be explained as the neural network models the training data too well and perform bad in data which is different from training data. 
  .KM  -KM 3UBREFRACTION    .KM OR    .KFT    -KM OR    -KFT4!",%  2EFRACTIVE 'RADIENTS AND #ONDITIONS. ÓÈ°n  2!$!2 (!.$"//+  ! SIMPLE RELATIONSHIP BETWEEN A DUCTS THICKNESS AND ITS ABILITY TO TRAP A PARTICULAR  FREQUENCY IS GIVEN BY   KC MAX  r 
 FIG. 4  FIG. 5  How can such curious wave-forms be produced? The  orthodox radio man will say at once, “‘Oh, these are  merely distortions of a true wave-form. 
 5.17. This voltage isperiodic and has magnitude depending onthe target cross section and onthe exact phase ofthe returned signal—a change ofrange ofh/4 resulting ina reversal ofsign. Ifthe target moves, the change ofrange cauees a periodic oscillation ofamplitude, the resulting signal being like that of Graph bFig. 
 It was not until 1971 that  international marine radar standards were agreed by the Intergovernmental Maritime  Consultative Organization (IMCO, the original name of IMO). However, the use of  radar on ships was first formally recognized by IMO in 1960 in an Annex to the  International Regulations for Preventing Collisions at Sea. The influence of the 1946  proposed international standard was evident in the 1971 performance standards, even  to the extent of using identical wording in a number of places. 
 The atmosphere may be characterized for present purposes by a single  temperature and a single loss, but it can be subdivided, ir desired, into an ionospheric compo­ nent, an oxygen component, and a water-vapor component. The combined temperature of  cosmic noise and atmospheric noise [Tc + (La, -l )T.,] is called the space temperature, the  brightness temperature, or the antenna temperature of an ideal antenna. The RF losses Lrr  indicated in the figure are meant to include the antenna, radome, and duplexer losses, as well  as transmission-line loss. 
 A. This phenomenon results in a platform-motion clutter power spectrum which is weighted by the antenna's two-way power pattern in azimuth. The true spectrum may be approximated by a gaussian spectrum, H(f) = e-l/2(fd^pm)2 = e-(VxQ/X<rpm)2 ^ G4(0) (J6 4) G4(0), the two-way power pattern of the antenna, is 0.25 when 0 = 6fl/2, where 0a is the half-power beam width which can be approximated by X/a, a being the effective horizontal aperture width. 
 Doppler-based systems, such as doppler navigators, moving-target indicators, and  synthetic-aperture radar systems, depend on the predetection spectrum for their opera - tion, because they are coherent and do not use amplitude or square-law detection. Moving-Target Surfaces.  Sometimes clutter has internal motion. 
 THE 
 RADAR ANTENNAS 249  Focus  . //.  (a) (b)  Figur<' 7.IR (a) Convrrging-kns antenna constructed of homogeneous solid dielectric. 
 For modern radar applications, the advent of electronically controlled phase  shifters, switches, and transmit/receive modules has once more directed attention to  array antennas. The aperture excitation may now be modulated by controlling the  phase of the individual elements to give beams that are scanned electronically. The  dramatic advantage of electronically steered phased arrays as compared to reflectors  is provided by the time required to steer beams and the flexibility in steering. 
 VI [ 2]. By this time many of the reliability and servicing problems had been improved, if not totally overcome. In August 1944, a trial of a prototype ASV Mk. 
 W. M., M. B. 
 This particular situation resulted from alack ofneed forvery high powers in this wavelength range. Figure 10.19 illustrates theeffects ofwavelength and power output on thedesign ofanode blocks. Inthetoprow, from lefttoright, are10-cm anode blocks formagnetrons with pulse power outputs of2500, 1000,” 250, 5,and 0.1kw. 
 Thearmsarerotatedto produce acontinuous anduniform variation ofphaseacrosstheelements ofthearray.When thephaseatoneendoftheconcentric lineisincreasing, thephaseattheotherendis decreasing. Henceonelinecansupplythenecessary phasevariation totwoelements, oneon eithersideofarraycenter.AtotalofNI2concentric ringsarerequired foralineararrayof N+1elements. Thereareseveralmethods forgenerating phaseshiftthatutilizetheproperties ofcircular polarization. 
 ,: ' . py~-~-l-* lUl ye1  $+-  I.  Figure 10.7 Block diagram of a binary moving window detector, or binary integrator. 
 ATE #&!2 PROCESSING CIRCUITS TO REJECT UNWANTED CLUTTER RESIDUE 7HEN CLUTTER SUP 
 Multipath effects can severely distort the pulse envelope, for example, by creating a long tail to the pulse and even displacing the position of the peak. The TOA of the pulse can be taken as the instant that a threshold is crossed, but in the presence of noise and distortion this becomes a very variable measure- ment. Nevertheless, the TOA is used for deriving the PRI of the radar. 
 Inversesynthetic aperture radar.Intheordinary synthetic aperture radarthetargetisstation­ aryandtheradarisinmotion.Theopposite willalsopermittargetimaging; thatis,theradaris stationary andthetargetisinmotion.Thisiscalledinversesynthetic aperture radarordelay­ dopplermapping. Although thesignalprocessing required issimilartothatofthtfconventional synthetic aperture radar,theinversesynthetic aperture processcanalsobeviewedasan equivalent doppler filtering. Eachpartofamoving targethasaslightly different relative velocity, ordoppler-frequency shift.Filtering thesevariousdoppler frequencies resolves the different partsofthetargettoprovide animage.Although theinversesynthetic aperture resultsfromrelativemotionofthetarget,justasdoesthecross-section amplitude fluctuations mentioned previously, theprocessing oftheinversesynthetic aperture radarsignalrequires a coherent system(onethatpreserves phase).Inprinciple, inversesynthetic aperture radarcan beusedtoimagemovingtargetssuchasaircraftandships.Ithasbeenappliedinthepastto imaging ofthemoonandtomapping thesurfacebelowthecloudssurrounding theplanet Venus.61 Polarization. 
 FLYING AIRCRAFT APPROACHING A TASK FORCE BELOW THE RADAR COVERAGE OF THE SHIPS ANTENNA 4HE ADVANTAGE OF THE AIR 
 SANDWICH  " 
 46.NTRODUCTION TORADAR SYSTEMS Thecross-section datapresented inthissectionleadtotheconclusion thatitwouldnotbe appropriate simplytoselectasinglevalueandexpectittohavemeaning inthecomputation of theradarequation withoutfurtherqualification. Methods fordealingwiththecrosssectionsof complicated targetsarediscussed inthenextsection. 2.8CROSS-SECTION FLUCTUATIONS Thediscussion oftheminimum signal~to-noise ratioinSec.2.6assumed thattheechosignal received fromaparticular targetdidnotvarywithtime.Inpractice, however, theechosignal fromatargetinmotionisalmostneverconstant. 
 360-361 Balanced mixers.348-349 BAM, 510~ Bandwidth: CWradar,75-76 effective. 404-405 klystron. 203 noise,18 tracking. 
 Airborne scanners show this relation very strongly. Asurvey ofweights’ indicates that, very roughly, the weight ofscanners having simple scans isgiven by0.09D2 pounds, where Distheparaboloid diameter ininches. The formula forcomplex scans isO.13D’. 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 voltage in the angle-error-detector output equal to angle error times the angle sen - sitivity. A slow AGC allows the amplitude noise to modulate the true tracking-error   voltage, causing additional noise in angle tracking. 
 The advantage of the airborne platform in extending the maximum detection range for air and surface targets is apparent when one considers that the radar horizon is 12 nmi for a 100-ft antenna mast compared with 123 nmi for a 10,000-ft aircraft altitude. Loss of picket ships due to kamikaze attacks led to the concept of the auton- omous airborne detection and control station. This type of system was further developed as a barrier patrol aircraft for continental air defense. 
 TO 
 The first MTI acoustic delC:lY lines were  liquid and used water or mercury. The development of the solid quartz delay iine for MTI  application in the 1950s offered greater convenience than the liquid lines. 33 The solid line is  constructed of many facets so that a relatively long delay time can be obtained with a small  volume by means of multiple internal reflections. 
 - -- --- -- - - -.  is illtlst rated scherriatically a lapped delay line that generates this Barker-coded waveform  when an inipulse is incident at the left-hand terniinal. The same tapped delay line can be used  as tlie receiver tilatched filter if the input is applied at the right-hand terminal. 
 CAVITY 474   C  EXTENDED  INTERACTION KLYSTRON  AND  D  4WYSTRON AFTER ! 3TAPRANS ET AL   Ú )%%%  )NTERACTION STRUCTURE0 0 ). 'UN )NTERACTION )MPEDANCE $ISTANCE A /UT #OLLECTOR : )MPEDANCE B  C )MPEDANCE )NPUT /UTPUT LOAD )MPEDANCE D .   4(% 2!$!2 42!.3-)44%2   £ä°£Î GAIN 
 These excursions can significantly increase the errors in angle tracking or measurement systems. When the returns from dominant scatterers are reduced in the bistatic region, the source and hence the magnitude of glint excursions are reduced. Limited measurements for tactical aircraft show that, for a 30° bistatic angle, peak glint excursions can be reduced by a factor of 2 or more, with most of the excursions contained within the physical extent of the target.54 Forward-Scatter RCS Region. 
 NUMBERED COEFFICIENTS  EXCEPT FOR THE ONE IN THE CENTER  ARE ZERO  SO THE FILTER IS VERY EFFICIENT TO IMPLEMENT  AS THE ZERO COEFFI 
 62–69,  July 14, 1980. 42. J. 
 I. Skolnik, Introduction to Radar Systems , New York: McGraw-Hill 2001, p. 88. 
 It is, however, costly and complex. The transmitter radiates a fan beam from  the summation of all overlapping pencil beams to give the desired elevation coverage. A  separate receiver is provided each pencil beam and some means of interpolation between the  beams is used to refine the angle measurement. 
 2& 53!   
 Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 23.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 104. T. 
 This chapter discusses some of the concepts involved in the extraction of information  from a radar signal. The next section considers in a qualitative manner the type of target  information available from a radar signal. The theoretical accuracies with which range, rela­ tive velocity (doppler frequency), and angle of arrival can be determined are derived in  Sec. 
 Foster, J. S.: A Microwave Antenna with Rapid Saw-Tooth Scan, Cirt~c~dht~ J. qf' Phys.. 
 This can bedone indiscrete fashion by switching the condenser, the resistance, or,within limits, the charging voltage. Continuous variation ismost satisfactorily accomplished by using arheostat forR(unless the control isremote) orbyvarying E through apotentiometer. Figure 13.30 illustrates both positive and negative sawtooth genera- tors using single-triode clamps. 
 J. A.: "Electromagnetic Theory." McGraw-Hill Book Company, New York. 1941. 
 NWRF 31-0660-035, 1960.  26. Hattan. 
 Superresolution might be able to resolve multiple  independent sources; due to sidelobe superposition and masking problems, superreso - lution might be vital for jammer mapping in case of multiple jammers. Superresolution  is also of interest as an ECCM to counter cross-eye jamming in seeker head applica - tions: see Section 12.1 of Wirth.102 The superresolution concept was mainly developed and analyzed by W. F. 
 III ASV Mk. VI ASV Mk. VII Peak power, Pt, kW 40 200 25 Frequency, f, Hz 3.3 ×1093.3×1099.375 ×109 Wavelength, λ, m 0.091 0.091 0.032 Pulse length, τ,μs1 1 1 Pulse repetition frequency, fr, Hz 660 660 660 Antenna gain, G,d B 2 4 2 4 3 3 Azimuth beamwidth, θ°az, deg 10 10 3.3 Elevation beamwidth *,θ°el, deg 15 15 6 Antenna polarisation H H H Scan rate, rpm 60 variable <40 variable <40 Pulse dwell, N 18 36 (30 rpm) 12 (30 rpm) IF frequency, MHz 13.5 45 45IF bandwidth, B, MHz 3.5 3.5 3.5 Estimated receiver noise figure and microwave loss, F nLμ,d B19 17 17 Signal processing loss, dB 8.5 8.5 8.5 *Antenna scanner not stabilised in pitch or roll; ﬁxed tilt ~0°. 
 21. S. M. 
 In previous work, the variation of beam central incident angle is never considered due to the observation geometry of the stripmap mode. However, for sliding spotlight mode, the beam scanning leads to the increase of incident angle which will prolong the signal propagation path in irregularity layer and further aggravates the signal decorrelation. The instant ionospheric incident angle is applied as a modiﬁcation of ACF for sliding spotlight mode which is presented as Rφ(ω1,ω2;Δx)=r2 eλ1λ2CsLsecθnsecθsq(ηm)·G/vextendsingle/vextendsingle/vextendsingle/vextendsingleΔx 2qL/vextendsingle/vextendsingle/vextendsingle/vextendsinglev−1/2Kv−1/2(q0Δx) 2π·Γ0(v+1/2)(11) where θsq(ηm)is the squint angle at the mthsampling point. 
 LING CLUTTER RESIDUE WITH INTENTIONALLY RESTRICTED DYNAMIC RANGE  HAS BEEN ADOPTED IN NEWER -4) SYSTEMS Ó°ÎÊ   1// 
 If a PPI were to  display relative bearing (azimuth) the apparent bearing would change as the platform yawed.  With the aid of a horizontal gyroscope to provide a north reference, a correction signal can be  obtained which can be applied to the indicator to permit the display of the target in its true  bearing rather than the bearing relative to the platform heading. Generally the top of the  display corresponds to north. 
 4.The grid-modulation characteristic ofmost electrostatic tubes follows approximately asquare law, whereas that oftheguns used inmost magnetic tubes iscubic. Ascompared with alinear response, these characteristics have the unfortunate property of lowering the dynamic range ofusable echo intensities since they reduce the ratio between the upper limit ofuseful signal swing, setbythe tendency todefocus, and the level below which the intensity isinsufficient. TAZLE 13.1.—CATH0DE-RA% TUBES COMMONLY USED iFOR RADAR APPLICATIONS Bulb number 2A 2B(New) 3B 3D(Central electrode) 3F 3J 3H 4.4 5B 5C 5F 5L 7B 9G 12G 12DJseful liam- eter, in. 
 Ng, = number of range gates in the output unambiguous-range interval (dis- play range/range-gate size) 7FR = false-report time [per Marcunr s definition where the probability is 0.5 that at least one false report will occur in the false-report time (Ref. 46)] Equation (17.22) is for the case where no doppler correlation is required for a target report. In the case where both range and doppler correlation are used, the required PFA is r 0.693 Td li/" PFA = (17-23) [(Z1)NpN8 TpRJf-1J where NJit = number of independent doppler filters in the unambiguous doppler region and W = width (in filters) of the correlation window applied to detections following initial detection. 
 106. A. D. 
   *ULY  AND REPRINTED IN $ + "ARTON   #7 AND $OPPLER  2ADARS  3ECTION )6n  6OL  .ORWOOD  -! !RTECH (OUSE  )NC    PP n  2 ( &LETCHER AND $ 7 "URLAGE  h!N INITIALIZATION TECHNIQUE FOR IMPROVED -4) PERFORMANCE IN  PHASED ARRAY RADAR v IN 0ROCEEDINGS OF THE )%%%  VOL   $ECEMBER   PP n  $ ( (ARVEY AND 4 , 7OOD  h$ESIGN FOR SIDELOBE BLANKING SYSTEMS v IN  0ROCEEDINGS OF THE   )%%% )NTERNATIONAL 2ADAR #ONFERENCE  7ASHINGTON  $#    PP n  , -AISEL  h0ERFORMANCE OF SIDELOBE BLANKING SYSTEMS v  )%%% 4RANSACTIONS ON !EROSPACE AND  %LECTRONIC 3YSTEMS  VOL !%3 
 The sheets are then stacked and arranged tobeedge-lighted individual] y;thus only the chosen scale appears. Such multiple scales areused ontheindicator oftheV-beam height-finding display described inSec. 6.12, topermit theuseofrange sweeps ofvarious lengths. 
 The angular-  error signal actuates a servo-control system to position the antenna, and the range output  from the sum charlnel feeds into an automatic-range-tracking unit.  The sign of the difference signal (and the direction of the angular error) is determined by  comparing the phase of the difference signal with the phase of the sum signal. If the sum signs1  Transmitter  Sum channel  r I- Range  TR -+-- Mixer - 1 F Amplitude >gnaal  amplifier detector  I  junction eTq,'"rid \ 1 Phase- Angle -  sensitive error  signal  \ Antenno  feeds  Mixer  Difference channel  Figure 5.8 Block diagram of amplitude-comparison monopulse radar (one angular coordinate). 
 Now  in radar the operator is looking at the end of the tube,  and if there is any danger of his touching part of the  apparatus it is the tube end. That, as we can see, may  quite often have a voltage of some 3000 applied to it,  enough to cause a fatal accident. In many radar out-  fits, therefore, the actual screen end of the tube is  brought to earth potential, and the high-voltage anode  in the tube is earthed. 
 S)stcmconsiderations. Oneoftheattractive features claimed foramultiple-beam-forming arrayisthatitdocsawaywithphaseshifters. Thesearereplaced, however, bymultiple receivers. 
  
 311–329, June 1960. 75. D. 
 --  "EFORE DIGITAL TECHNOLOGY BECAME WIDELY AVAILABLE  ANALOG TECHNIQUES WERE  EMPLOYED TO GENERATE RADAR TRANSMIT WAVEFORMS 3IMPLE PULSED SYSTEMS USED ANALOG 2& SWITCHES TO GATE THE ,/ ON AND OFF &REQUENCY MODULATED SIGNALS WERE GENERATED BY SURFACE ACOUSTIC WAVE 3!7  DEVICES 3IMPLE BINARY PHASE MODULATION SCHEMES  LIKE PSEUDO 
 PLANE )N THE CONFIGURATIONS SHOWN  THE ZEROS ARE CON 
 6.12. Ifseveral scales aretobeused inconnection with delayed sweeps, the reflection method ofFig. 7.4is used. 
 out too much error. A pulse of length T is transmitted from an antenna of beamwidth c|>0. For the simple illustration given here, we assume the pulse to be transmitted directly ahead of the horizontally moving vehicle. 
   PP n  -ARCH   ' ! !NDREWS  h!IRBORNE RADAR MOTION COMPENSATION TECHNIQUES /PTIMUM ARRAY CORRECTION   PATTERNS v .AVAL 2ES ,AB 2EPT   -ARCH     ! 2 ,OPEZ AND 7 7 'ANZ  h#0#4 ANTENNAS FOR !-4) RADAR  VOL  4HEORETICAL STUDY v !IR  &ORCE !VIONICS ,AB 2EPT 7,  !$   *UNE  .OT READILY AVAILABLE   , % "RENNAN  * $ -ALLETT  AND ) 3 2EED  h!DAPTIVE ARRAYS IN AIRBORNE -4) RADAR v  )%%%  4RANS  VOL !0 
 spaced athalf-wavelength intervals with minima halfway between them. Only iftheline isperfectly matched willthevoltage reading beconstant as theprobe moves along. The ratio ofthemaximum totheminimum volt- age iscalled the “voltage standing-wave ratio” (VSWR) and istheusual criterion ofhow well aline ismatched. 
 It requires a plate voltage of 17.5 kV, plate current of  183 A. 1.57 V filament voltage and 890 A filament current. The tube is 76 cm long, 42 cm in  diameter and weighs 63.5 kg. 
 ARY NOTATION INDICATES HORIZONTAL OR VERTICAL LINEAR  POLARIZATIONS ON BOTH TRANS 
 Operationally they can be a  nuisance, because they tend to clutter up the line of  light at places where we might find echoes of essential  objects. The most that can be said for permanent  echoes—or ‘PE’s,’ as they are called—is that they do not  move along the trace (unless a building or hillside  decides to perambulate), and so can be picked out.  The real trouble caused by PE’s is that the great majority  of them are found near at home, and thus even though  we suppress the blip caused by the transmitter the first  part of the trace is not very helpful to us, because it is  confused with a mass of superimposed short-range  echoes. 
 ABLE ON A SHORT TERM BASIS 4HE RADAR DESIGNERS PROBLEM IS TO SELECT THE BEST WAVEFORM IN THIS TARGET 
 7.Slaprans, A.,E.W.McCune, andJ.A.Ruetz:High-Power Linear-Beam Tubes,Proc.IEEE,vol.61, pp.299-330, March,1973. 8.Lien,E.L.:Advances inKlystron Amplifiers, Microwave J.,vol.16,pp.33-36,39,December, 1973. 9.Dodds,W.J.,T.Moreno, andW.J.McBride, Jr.:Methods ofIncreasing Bandwidth ofHighPower Microwave Amplifiers, IREWESCON Conv.Record,vol.1,pt.3,pp.101-110, 1957.. 
 and b. There have been less measurements of the Z-rrelationship for  snow than for rain, and there have been several different values proposed for the constants a  and b. The following two expressions have been suggested  z = 2000,2  z = t 780r2·21 ( lJ.25a)74  (l3.25h}75  Measurements show a correlation between surface temperature and the coefficient a of the  Z = arb relationship, which suggest the following 76  z = 1050r2 for dry snow (ave temp. 
 16.16 .—I-f locking, r-f addition. (a) I-f locking by transmitter, r-f addition. (b)I-fIockhg byoscillator, r-faddition. 
 The pulse  repetition frequency might be switched every other scan or every time the antenna is scanned a  half beamwidth, or the period might be alternated on every other pulse. When the switching is  pulse to pulse, it is known as a staggered prf.  An example of the composite (average) response of an MTI radar operating with two  separate pulse repetition frequencies on a time-shared basis is shown in Fig. 
 € x(t)=cos( 2πf0t+1 2bt2)  € b=2πB τ(FM−Rate )= cos(ω0t+1 2bt2);−τ 2<t<τ 2 x(t)=0otherwise  (8.20)      The matched filter, which represents the ideal compression filter, has the function:   € h(t)=2b π⋅cos(ω0−1 2bt2);−τ 2<t<+τ 2 (8.21)  With a normalizing factor of πb2 , Equation (8.19) results in:   dtt tb t t bt tbtg )) (21) ( cos()21cos(2)(2 0 0 022 20 0 − −− ⋅ + = ∫+ −ω ωππ π  (8.22)  The result is obtained after many transformations.   € g(t0)=2b πcos(ω0t0)⋅sin(bt0 2(τ−t0)) bt02 (8.23)   A comparison of compressed pulses with short pulses of the same bandwidth shows that the  same precision and resolution cannot be achieved with FM compression.  The deterioration is identified as compress ion loss. 
 Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 
 FIELDS ARE RELATED TO !VIA SIMPLE DERIVATIVES ANDOR VECTOR   MULTIPLICATIONS  )N PRACTICE  %Q  IS COMPUTED AS A SUMMATION OF NUMERICAL INTE 
 No. 85CH2076-8.) 16. Wolverton, R. 
 An example of the elevation angle error at low angles is shown in Fig. 5.16 for a target at  constant height.43 At close range the target elevation angle is large and the antenna beam does  not illuminate the surface; hence the tracking is smooth. At intermediate range, where the  elevation angle is from 0.8 to as much as six beamwidths, the surface-reflected signal enters  the radar by means of the antenna near-in sidelobes. 
 If  the power conditioner frequencies cannot be sufficiently attenuated, their frequency  should be synchronized to a multiple of the PRF of the CPI so that modulations repeat  precisely pulse-to-pulse and thus will cancel like stationary clutter . Rule 3.  Design the system to be fully coherent. 
 Because target contours are difficult to change once the target has become a production item, shaping is best imple- mented in the concept definition stage before production decisions have been made. Radar-absorbing materials actually soak up radar energy, also reducing the energy reflected back to the radar. However, the application of such materials can be expensive, whether gauged in terms of nonrecurring engineering costs, lifetime maintenance, or reduced mission capabilities. 
 chap.22of"RadarHandbook." M.I.Skolnik (ed.).McGraw­ HillBookCompany. NewYork.1970. :'.1.Fvanzia. 
 LEVEL $"&  BECAUSE SUBARRAY 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 r Thecross section istherefore IfIt]>>1, which istrue, forinstance, foraraindrop, simpler expression ()27ra~~=4—Ta~, x’(3) (4) weobtain the (5) which inthis form serves tocompare the radar cross section with the ‘(geometric cross section’’ raz. Forthe case ofametal sphere, onewould betempted touse thesame formula with [cl=CO. This, however, isnot correct, because, inthe case ofaconducting sphere, surface currents which have amagnetic dipole moment are induced bythe field. 
 Xing, X.; Ji, K.; Zou, H.; Chen, W.; Sun, J. Ship classiﬁcation in TerraSAR-X images with feature space based sparse representation. IEEE Geosci. 
 Mk. VI Policy, RAF, File S.14403/6, Minutes of ‘A Special Meeting held in Room 71/II, Air Ministry, Whitehall, S.W.1, on Wednesday, 27th October, 1943, at 1545 hours ’ (TNA AIR 15/117) [8] Thompson F C 1945 Fundamentals of H2S TRE J. 15 –51 (reprinted in e-Defence Electronics Newsletter, The Defence Electronics History Society, No 50 Part II: September 2016) [9] ASV Mark VI —ARI 5568, and ASV Mark VIA —ARI 5571, TRE Report T.1664, 16th April 1944 (TNA AVIA 26/666) [10] Performance of ASV Mk. 
 The jamming  signal causes the SAR to receive and process erroneous information that results in  severe degradations in the SAR images and/or formation of the image of nonexistent  targets. A deception jamming could be composed of manipulated replicas of the  transmitted radar signals via DRFM. In Hyberg168 the possibility of preventing SAR  mapping through coherent DRFM jamming has been investigated. 
 ERS  ,/ SIGNALS NOT EXACTLY  O APART  AND MISMATCHES IN THE GAINS  $# OFFSETS  OR  FREQUENCY RESPONSES OF THE ) AND 1 SIGNAL PATHS ! $$# AVOIDS THESE PROBLEMS  THOUGH IT IS VULNERABLE TO THE PHASE NOISE OF THE !$# SAMPLE CLOCK  !$# NONLIN 
 Similar beliavior is exhibited at 30" grazing angle. The effect of wind at C band is  like that at X band. At lower frequencies, however, the variation of o0 with wind is less  pronoitr~ced. 
 Parris, and R. Stapleton,  “Development of a digital array radar,” IEEE AEES Systems Magazine , pp. 22–27, March 2002. 
  3   # PERCENT BY WEIGHT  WHERE 3 AND # ARE THE PERCENTAGES BY WEIGHT  OF SAND AND CLAY IN THE SOIL 4HE SOIL  MOISTURE CONTENT IN TERMS OF FIELD CAPACITY IS   MF   MG&# PERCENT  WITH MG THE PERCENT MOISTURE IN THE SOIL BY WEIGHT 7HEN WE USE THIS MEASURE  THE RELA 
 LOBED PATTERN CAN BE USED FOR MAIN 
 Knowledge-Aided DBS Super-Resolution Imaging Algorithm3.1. Spatial Continuity Property of the Echoed Signal When the antenna of the airborne WAS radar scans the surveillance region, the radar illuminates the imaging scene continuously through the scanning movement of the antenna beam. Since the antenna beam is steered from one azimuth viewing angle to another, a target may be illuminated by many pulses in one CPI in the very short dwell time. 
 I., and G. I). Smith: Propagation in an Evaporation Duct: Results in Some Simple Analytic  Models. 
 BOUNCE TARGET IE  A  SPHERE OR FLAT PLATE  WILL REQUIRE AN ANTENNA MATCHED TO THE OPPOSITE SENSE OF CIRCULAR POLARIZATION FROM THAT TRANSMITTED )F THE SAME ANTENNA IS USED  THEN SINGLE 
 Tracking through the zenith is possible without encountering impractical drive  accelerations. Such a mount, however, transfers the problem of excessive accelerations to some  other direction; in this case, in the direction of the elevation axis. A three-axis mount avoids  the problem of excessive acceleration. 
 25. Ballard, A. H.: Rosette Constellation of Earth Satellites, IEEE Trans., vol. 
 Weinstock38•40 showed that this distribution can describe certain simple  shapes, such as cylinders or cylinders with fins that are characteristic of some satellite objects.  The parameter m varies between 0.3 and 2, depending on aspect. These have sometimes been  called Weinstock cases. 
 In general, the effective noise temperature has been preferred f9r describing  low-noise devices, and the noise figure is preferred for conventional receivers. For radar  receivers the noise figure is the more widely used term, and is what is used in this text.  Measurement of noise figure. 
 The spacing betwe-~n the taps is equal to the range ;esolution. The Oulputs from  the delay line taps are summed. This sum, when multiplied by the appropriate constant,  determines the threshold level for achieving the desired probability of false alarm. 
 The multiple-PRF true-ranging system is the most positive solution. Once true range has been determined so that the range ambiguity is resolved, PRF switch- ing eliminates eclipsing. The onset of eclipse is detected by the range tracker by noting when the range gate begins to overlap the transmitted pulse. 
 K.: Comb Filter Design, Naval Research Laboratory, Washington, D.C. Mrmorand~rm Report  2433, May, 1972.  148INTRODUCTION TORADAR SYSTEMS radaratthedifference frequency butithasnoneofitsotherfavorable cluttercharacteristics. 
 LENGTH DIGITAL WORDS "OTH THE SAMPLING AND QUANTIZATION PROCESS PRODUCE ERRORS THAT MUST BE MINIMIZED IN ORDER TO LIMIT THE RADAR PERFORMANCE DEGRADATION )N ADDITION  A VARIETY OF OTHER ERRORS SUCH AS ADDITIVE NOISE  SAMPLING JITTER  AND DEVIATION FROM THE IDEAL QUANTIZATION  RESULT IN NON 
 The origin ofthe PPI may beatthecenter ofthe cathode-ray Lube, giving anequal field ofview inalldirections. Frequently, however, FIG.65.-Off-center PPI. itisdisplaced, sometimes faroffthetube face, inorder togive amaxi- mum expansion toagiven region; such adisplay iscalled ano~-center PPI (Fig. 
 There is even less information on clutter at  frequencies above 10 GHz. Details wiJI not be given here, but the general trends will be  summarized for the several types of clutter that have been measured.  The a~·rage clutter cross section per unit area ror one set of measurements of trees and  vegetation at millimeter wavelengths is given by 75•102  o-0(dB) = -20 + 10 log (0/25) -15 log ...1. 
 C. DiPietro, and R. L. 
 7.16. The parabolic torus is gen-  erated by rotating a section of a parabolic arc about an axis parallel to the latus rectum of the  parabola. The cross section in one plane (the vertical plane in Fig. 
 4 London: IEE Books, 1993, p. 104. 18. 
 p. 11. h:hlll·  ary, 1936. 
 2'0/  TECHNIQUES WILL BE DESCRIBED ! 
 MIL-6, pp. 169-173, April, 1962.  27. 
 The higher the operating  frequency the easier it is to obtain wide signal and wide tunable bandwidth. A limitation on the availability of bandwidth in a radar is the control of the spectrum  by government regulating agencies (in the United States, the Federal Communication  ch01.indd   8 11/30/07   4:33:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The video  bandwidth B,. must be greater than B,F/2 in order to pass all the video modulation. Most radar  receivers used in conjunction with an operator viewing a CRT display meet this condition and  IF Second Video  amplifier 1- ~ amplifier  (81,) detector (Bvl Figure 2.3 Envelope detector. 
 Another method of suppressing the altitude return in the pulse radar is to  eliminate the signal in the frequency domain, rather than in the time domain, by inserting a  rejection filter at the frequency .fo. ,The same rejection filter will also suppress the transmitter­ to-receiver leakage. The clutter energy from the main beam may also be suppressed by a  rejection filter, but since the doppler frequency of this clutter component is not fixed, the  rejection filter must be tunable and servo-controlled to track the main-beam clutter as it  changes because of scanning or because of changes in aircraft velocity. 
 J.: The Groove Guide. a Low-Loss waveguide for Millimeter Waves. IEEE Tratls,  vol. 
 Heimiller, J. E. Belyea, and P. 
 (E-plane metal-plate lens.)  (7.20)250INTRODUCTION TORADAR SYSTEMS Whentheparticles aremetaIlic spheresofradiusaandspacingsbetween centers, the dielectric constant oftheartificial dielectric isapproximately (= 1+41r~l3 5 assuming nointeraction between thespheres.47 Anartificial dielectric mayalsobeconstructed byusingasoliddielectric material witha controlled patternofvoids.ThisisaformofBabinet inverseofthemoreusualartificial dielectric composed ofparticles imbedded inalow-dielectric-constant material.4!lThevoids maybeeitherspheresorcylinders, butthelatterareeasiertomachine. Lensesmadefromartificial dielectrics aregenerally oflessweightthanthosefromsolid dielectrics. Forthisreason,artificial dielectrics areoftenpreferred whenthesizeoftheantenna is large,as,forexample, atthelowerradarfrequencies. 
 9.7 SOURCES OF ERROR There are many sources of error in radar-tracking performance. Fortunately, most are  insignificant except for very high-precision tracking-radar applications such as range  instrumentation, where the angle precision required may be of the order of 0.05 mrad  (mrad, or milliradian, is one thousandth of a radial, or the angle subtended by 1-m  cross-range at 1000-m range). Many sources of error can be avoided or reduced by  radar design or modification of the tracking geometry. 
 The collapsing loss is the additional  signal required to maintain the same PD and Pfa when unwanted noise samples along  with the desired signal-plus-noise samples are integrated. The number of signal sam - ples integrated is N, the number of extraneous noise samples integrated is M, and the  collapsing ratio r = (N + M)/N. ● Most automatic detectors are required not only to detect targets but also to make angu - lar estimates of the azimuth position of the target. 
 The calibration of the radar does, of course, depend on stable  system characteristics and antenna parameters that are invariant with the spacing of  the front surface and the antenna. Although on first consideration, frequency domain  radars should offer a superior sensitivity to time-domain radars, because of their lower  IF receiver bandwidth and hence thermal noise, both the type of receiver and the range  sidelobes of the radiated spectrum may result in an equivalent or worse sensitivity in  terms of range resolution as discussed above. Pseudo-random-coded Radar. 
   2EV !  -ARCH    * % 6OLDER  h4HE #/2$)# TRIGONOMETRIC COMPUTING TECHNIQUE v  )2% 4RANS ON %LECTRONIC  #OMPUTERS  VOL %# 
 TANCE FOR PULSED OPERATION  BUILT 
 vol. AES-8. pp. 
  K(Z TO    K(Z WITH RESPECT  TO THE )& CENTER FREQUENCY  -(: TOTAL PASSBAND  AT THE  
 The parameter x might represent a voltage, and (x2).,. the mean, or  average. value of the voltage squared. 
 The main source of noise is termed thermal noise  and is due to agitation of  electr ons caused by heat. The noise can arise from    received atmospheric or cosmic noise    receiver noise - generated internally in the radar receiver.   The overall receiver sensitivity is directly related to the noise figure of the radar receiver. 
 The usual method isillustrated inFig. 13.40. The principal T#mingpulse J.1 Modulator Rectangular Ir–-----l Inter.wavepulse generator Pulse. 
 The output of each stage is multiplied by weight ai9 which is either +1 or — 1 in ac- cordance with the reference sequence. The summation circuit provides the out- put correlation function or compressed pulse. Figure 10.136 shows an implementation where the reference may be changed for each transmitted pulse. 
 An array of antenna elements collects the radiated energy and passes it through the  phase shifters which provide a correction for the spherical wavefront, as well as a linear phast:  shift across the aperture to steer the beam in angle. Another set of elements on the opposite  side of the structure radiate the beam into space. The primary pattern of the feeti illuminating  the space-fed array provides a natural amplitude taper. 
 POINT FEED IS USUALLY SMALL TO PRODUCE A BROAD PATTERN AND MUST BE COMPACT TO AVOID BLOCKAGE OF THE ANTENNA APERTURE )N SOME CASES  THE SMALL OPTIMUM SIZE REQUIRED IS BELOW WAVEGUIDE CUTOFF  AND DIELECTRIC LOADING OF THE HORN APERTURES BECOMES NEC 
 " 
 10.6, an alert, trained operator viewing a properly designed cathode-ray tube display is  a close approximation to the theoretical postdetection integrator.  The efficiency of postdetection integration relative to ideal predetection integration has  been computed by Marcum10 when all pulses are or equal amplitude. The integration  efficiency may be defined as follows:  (2.31)  where n = number or pulses integrated  (S/N)i = value of signal-to-noise ratio of a single pulse required to produce given probability  of detection (for n = 1)  (S/ N),, = value of signal-to-noise ratio per pulse required to produce same probability or  detection when n pulses are integrated  The improvement in the signal-to-noise ratio when n pulses are integrated postdetection is  nE1(n) and is the integration-improvement factor. 
 BEAM CLUTTER 4HE RESULT IN THE SPECTRAL DOMAIN IS SPURIOUS MODULATION SIDEBANDS 2ANDOM MULTIPLICATIVE NOISE BROADENS THE SPECTRUM OF THE CAR 
 L. Fante and J. A. 
 FOLDED CLUTTER )N PARTICULAR  THE CLASS OF &- 
 The If represents  the performance of the adaptive array: it accounts for the target signal integration  and the interference cancellation. Practical applications of the equation above are, for  instance, in Chapter 5 of Farina.34 Crucial for the understanding of the adapted array  pattern is the concept of eigenvalue-eigenvector decomposition of the interference  covariance matrix M: see again Chapter 5 of Farina34 and Testa and Vannicola.99 An  important technique that mitigates the deleterious effects of the noise eigenvectors,  thus continuing to maintain a prescribed level of low sidelobes in the adapted array  pattern is the so-called diagonal loading.100,101 Adaptive arrays came about after the successful application of SLC, the applica - tion of Eq. 24.6, and of more general and powerful adaptive array concepts (e.g.,  GSLC: generalized SLC34). 
 ZMAR, MAR, Typhon, Hapdar, ADAR, MERA, RASSR, and others. Although much  effort and funds have been expended, except for limited-scan arrays there has been no large  serial production of such radars comparable to the serial production of radars with mechan­ ically rotating reflector antennas.  8.12 ADVANTAGES AND LIMITATIONS  The array antenna has several unique characteristics that make it a candidate for considera­ tion in radar application. 
 37, March,  1959.  22. Knop, C. 
 BAND  ^ '(Z  OR # 
  ))  PP n  !PRIL   * 2 "ARNUM AND % % 3IMPSON  h/VER 
 44. M. I. 
 The  surface-reflected signal may be thought of as originating from the image of the target mirrored  by the earth's surface. Thus, the effect on tracking is similar to the two-target model used to  describe glint, as discussed previously. The surface-reflected signal is sometimes called a  multipath signal. 
 Note that the first blind speed of the composite  response is increased several times over what it would be for a radar operating on only a single  pulse repetition frequency. Zero response occurs only when the blind speeds of each prf  coincide. In the example of Fig. 
  
 The intersec - tion of these ellipses, or constant range-sum contours , locate the target. It is similar to  multilateration  because only range measurements are used to locate the target. * A multistatic radar can also use triangulation  for target location by taking simul - taneous target DOA measurements from multiple receive sites at known locations. 
  HIGH PRECISION TRACKING RADAR MEASURED UNDER IDEAL #OMPONENT "IAS .OISE 2ADAR 
 The extensive use of digital signal processing of radar data has resulted in a  demand for converters with both state-of-the-art sampling rates and dynamic range. Analog to digital converters transform continuous time analog signals into discrete  time digital signals. The process includes both sampling in the time domain, convert - ing from continuous time to discrete time signals and quantization, converting from  continuous analog voltages to discrete fixed-length digital words. 
 RANGE REGION  WHERE THE IMAGE APPEARS WITHIN THE HALF 
 3.3.1 Waveform generator type 26 The waveform generator acted as the master clock for the radar, providing the timing waveforms for the scanner, the PPI and height tube displays, and the modulator. Thebasic timing reference was a free-running multivibrator with a repetition interval of 1500μs ± 10%, giving a nominal pulse repetition frequency (PRF) of 660 c/s. 3.3.2 Transmitter –receiver (T 2R unit) TR. 
 ^KiW1 + mK2W2 + • • • + mKKWK = WqK which can be expressed in matrix notation as MW = Wq (16.24) This set of equations can be solved for the steady-state set of weights Wl to WK, which can be expressed in matrix notation as the familiar equation W= M~lWq (16.25) These weights have been shown17'18 to be the optimum set which maximizes the signal-to-interference ratio. Because of the smoothing required to keep the weights from jittering,18 the weights adapt to their steady-state values in a time determined by the clutter power and the allowable steady-state variation in the weights. Other algorithms19 can speed up the adaptation rate, but a more com- plex mechanization is required. 
 The jamming signals in the channels may be regarded as samples of a stochastic process having zero mean value and a certain time autocorrelation function. For linear prediction problems, the set of samples V is completely described by its Af-dimensional covariance ma- trix M = E(V*V7), where E(.) denotes the statistical expectation, the asterisk * indicates the complex conjugate, and Vris the transpose vector of V. The statis- tical relationship between VM and V is mathematically represented by the N- . 
 HF OVER-THE-HORIZON RADAR  20.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 20.8 CLUTTER: ECHOES FROM   THE ENVIRONMENT Earth Surface Clutter.  The geometry of skywave illumination ensures that tar - get echoes will be immersed in returns from the Earth’s surface, that is, clutter. In order  to detect the targets, the properties of this clutter need to be understood so that the  choice of frequency, waveform, and signal processing are compatible with the need to  separate target echoes from clutter, and also so that the required dynamic range of the  radar can be correctly specified. 
 Resolution, 20 ft (6 m). (Courtesy of En- vironmental Research Institute of Michigan.) storage must be read out for performing the azimuth compression and the pulse compression. Motion Compensation. 
 38. Tang Dazhang, S. G. 
 Proportional navigation is based on the fact that if two objects are closing on each other, they will collide if the LOS does not rotate in inertial space, as illus- trated in Fig. 19.4. Any rotation of the LOS (i.e., an LOS rate) is indicative of a deviation from the collision course which must be corrected by a missile maneu- ver. 
            &)'52%  4YPICAL '02 SYSTEM #OURTESY 53 2ADAR  &)'52%  4YPICAL DISPLAY FROM '02 .   '2/5.$ 0%.%42!4).' 2!$!2   Ó£°Î DIELECTRIC VARIATION  NOT NECESSARILY INVOLVING CONDUCTIVITY  WOULD ALSO PRODUCE REFLEC 
 J. R. Guerci, Space-Time Adaptive Processing for Radar , Norwood, MA: Artech House, 2003,  pp. 
 AES-4, pp.  4 10 - 4 16, May, 1968.  37. 
 'RUMMAN 3PACE 4ECHNOLOGIES !STRO !EROSPACE GROUP  HAS BEEN SUCCESSFULLY LAUNCHED AND DEPLOYED AND IS CURRENTLY IN USE ON SEVERAL COMMUNICATION SATELLITES   ! TOTAL OF FIVE REFLECTORS OF APERTURE DIAMETERS  METERS   METERS  AND  METERS HAVE BEEN FLOWN 3TUDIES HAVE ADDRESSED THE POTENTIAL USAGE OF  THIS REFLECTOR TECHNOL 
 pp. 180-199. February, 1977. 
 ENERGY DISTRIBUTION OF ANGLE SCINTILLATION MEASURED ON THE NOSE  ASPECT OF A SMALL TWO 
 SPREAD ECHOES WITH THE POTENTIAL TO OBSCURE TARGETS  3CATTERING FROM THE AURORAL REGION HAS BEEN STUDIED EXTENSIVELY USING THE 3UPER$!2.  (& RADAR NETWORK INITIATED BY 'REENWALD   AND AN AURORAL ECHO 
 Knight (eds.), vol. 2, London: Peter Peregrinus, Ltd., 1983. 19. 
 Hovanessian, S. A.: Medium PRF Performance Analysis, IEEE Trans., vol. AES-18, pp. 
 The  TPS-63 produces a much sharper slope at  the horizon than a shaped reflector of equal  height. The array feed enables superposi - tion of beams close to the aperture normal,  thereby enabling very high taper efficiency  (near full aperture gain). FIGURE 12.17  Paraboloidal reflector aperture shapes or rims: ( a) round outline/rim, ( b) oblong,  (c) offset feed, ( d) mitered corner, ( e) square corner, and ( f ) stepped corner FIGURE 12.18  AN/TPS-63 parabolic-cylinder   antenna ( Courtesy Northrop Grumman Corporation ) ch12.indd   18 12/17/07   2:31:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
  !S WITH SURVEILLANCE RADARS  SIDELOBE NOISE JAMMING AND DECEPTION  CAN BE FURTHER ATTENUATED BY THE USE OF 3,# IN CONJUNCTION WITH 3,"  AS DESCRIBED IN 3ECTION  4HE USE OF HIGHER TRANSMISSION FREQUENCIES FOR TRACKING RADARS GENERALLY MAKE THEM  LESS SUSCEPTIBLE TO NOISE JAMMING THAN SURVEILLANCE RADARS )N  ADDITION  TACTICAL TRACK 
 Y PLANE OF  $X   $Y   K  )N PRACTICE  THE  ACTIVE ARRAY ELEMENTS ARE TURNED ON ONE AT A TIME IN COORDINATION WITH THE PROBE POSI 
 The height control on the switch unit was adjusted until this blip disappeared into the height return and the aircraft height was read from the dial of the control on the switch unit. A range ring was also available. This appeared as a bright ring on the PPI or another blip (to the right) on the height tube. 
 For present purposes it will be  assumed that the aperture extends in one dimension only. This might represent the distribution  across a line source or the distribution in one plane of a rectangular aperture. If the constant . 
 PEAK VALUE OF  AP P 4HE VALUE OF THE PEAK PHASE 
 (23.19) is not especially representative of shower rainfall. Dennis30 has done considerable work in examining rainfall determinations in shower-type activity. His observations show that the reflectivity factor Z(mm6/m3) of an element of a vertical slice taken through a spherical shower cell is well represented by a regression line of the form Z = Cl(ro - r)c2 (23.20) In Eq. 
 CLUSION THAT 34!0 WILL IMPROVE PERFORMANCE 34!0S ABILITY TO INTEGRATE CLUTTER CANCELLATION TEMPORAL  AND SPATIAL INTERFERENCE  CANCELLATION CAN BE QUITE IMPORTANT TO MANY RADAR SYSTEMS WHETHER THEY TYPICALLY HAVE TO DEAL WITH INTENTIONAL JAMMING INTERFERENCE OR UNINTENTIONAL OR CASUAL  ELECTROMAGNETIC INTERFERENCE %-)  34!0 GETS AWAY FROM CASCADED SOLUTIONS SUCH AS ANALOG SIDELOBE CANCELLERS FOLLOWED BY DIGITAL $0#! ANDOR -4) FILTERSTHAT DO NOT GENERALLY CREATE AN OPTIMUM INTERFERENCE CANCELLATION SOLUTION /PTIMAL !DAPTIVE 7EIGHTS -C'UFFIN   4HE OPTIMAL LINEAR ESTIMATE IS DETER 
 This was men-  tioned in Sec. 8.4.  The other is a receive-only ntethod that uses a receiving array with rnixers and local  oscill:~tors (Lor;), arrarigecl so as to provide N separate receiving beams fixed in space  (Fig. 
 Extended  clutter tends to be noise like and will not pulse-compress, which keeps down inter - ference displayed to operators.29 The disadvantages of pulse compression are related  to the long duration of the coded pulse, which gives more time for the ECM equip - ment to process the pulse. In many cases, pulse compression can provide the means  for easy radar jamming for the enemy ECM operator. Pulse compression is also  vulnerable to cover-pulse jamming, in which the ECM pulse is returned to the radar  with a high JNR such that the normal target return is covered by the jamming pulse. 
 This chapter will provide a high-level outline of some of the major digital pro - cessing techniques for radar systems that have become practical since the Second  Edition of this Handbook  was published, as well as some design tradeoffs that need  to be considered.Chapter 25 ch25.indd   1 12/20/07   1:39:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 
 IRE.) . 238 INTRODUCTION TO RADAR SYSTEMS  radiated toward the edge of the reflector should usually be about one-tenth the maximum  intensity. The aperture distribution at the edges will be even less than one-tenth the maximum  because of the longer path from the feed to the edge of the reflector than from the feed to the  center of the dish. 
 / ÊÊ ,"1  Ê, 
 In the bistatic case, the isodops are skewed  away from the look angle, depending upon the geometry and platform motion, and  the clutter is called nonstationary . Bistatic isodops are developed analytically for  two dimensions and a flat earth by setting fTR = constant in Eq. 23.12 and solving  for qR (or q T, if appropriate). 
 Sometimes both conditions  cannot· he met simultaneously and a compromise is necessary. The upper cutoff frequency is  selected to pass the highest doppler frequency expected.  The indicator might be a pair of earphones or a frequency meter. 
 Harriger, “Medium PRF for the AN/APG-66 radar,” in IEEE Proceedings ,   vol. 73, no. 2, p. 
 Farina, E. Giaccari, F. Madia, R. 
 ccEEEEE WTIIS     WHERE  D` IS THE REAL PART OF THE DIELECTRIC PERMITTIVITY   D`   REAL PART OF THE DIELECTRIC PERMITTIVITY  Dp   IMAGINARY PART OF THE DIELECTRIC PERMITTIVITY  Dc   HIGH FREQUENCY LIMITING VALUE OF THE PERMITTIVITY. 
 600 EXAMPLES OFRADAR SYSTEM DESIGN [SEC. 15.8 adequate forasimple tracking orcontrol problem, but complex problems clearly called forhigher scan rates even attheexpense ofcoverage. Foreseeing awide range ofapplications forthenew radar equipment, itsdesigners provided anantenna drive bymeans ofwhich the scanning rate could beadjusted over therange from 1to6rpm. 
 162THEGATHERING ANDPRESENTATION OFRADAR DATA [S’EC. 62 Informing the displays, radar echo signals may beused either to displace (deflection-modulate) the electron beam, asinthe ordinary oscilloscope, ortointensify (intensity-modulate) it,asisdone intelevision. Deflection modulation affords precise information about the strength and character ofthe signals delivered bythe receiver, but leaves only one dimension ofthetube face free torepresent ageometrical quantity. 
 S. Hartwick, and M. T. 
 This version scans over arange ofelevation angle from ~to7#. The beam- tilting isachieved byaltering the relative phasing ofthe groups of dipoles; each group isfed from amechanical phase shifter mounted in thecenter ofthemast. The banks ofdipoles can betilted mechanically. 
 IEEE T rans. Aerosp. Electron. 
 Against a single clutter source, an implementa - tion is required that permits the MTI clutter notch to be shifted as a function of range.  An example of such an adaptive MTI implementation is shown in Figure 2.85. The  phase-error circuit compares the clutter return from one sweep to the next. 
 Attain- ment of very long life, in the region of 10,000 h or more, requires judicious se- lection of power ratings, conservative cathode-current density, and conscientious counseling of the marriage between tube and transmitter. RF Tube Power Capabilities. The peak power capabilities of RF tubes have progressed sufficiently far that the limitation has become breakdown in practical waveguide systems, even with 20 lb/in2 of SF6 in the waveguide. 
 205-213. 37. Hovanessian, S. 
          
 ,.0.672 0.5 ;. DETECTION OF RADAR SIGNALS IN NOISE 375  the values of Br which maximize the signal-to-noise ratio (SNR) for various combinations of  filters and pulse shapes. It can be seen that the loss in SNR incurred by use of these non-  matched filters is small. 
 Therefore, the problem of distinguishing di ﬀerent scatterers at di ﬀerent azimuth angles can be transformed into the problem of distinguishing di ﬀerent scatterers at di ﬀerent Doppler frequencies. Suppose a scatterer is located at the azimuth angle θ0, and the azimuth angle θ0is also the center of the antenna beam. The boundaries of the antenna beam can be denoted as θ0–Δθ/2 andθ0+Δθ/2, which correspond to the Doppler frequencies fdhand fdl, respectively. 
 Methodology The SBAS-InSAR method is used to process Radarsat-2 WUF SLC images in the ENVI SARScape module to obtain land subsidence information in Wuhan city [ 31]. The SBAS-InSAR method is an advanced InSAR technique that could improve the monitoring accuracy [ 51]. The SBAS-InSAR method relies on an appropriate combination of differential interferograms within the thresholds of temporal and spatial baselines, so the geometric decorrelation is minimal [ 26,31,36,52]. 
 SIDELOBEnVOLTAGE RATIO APPROACHES O  - 
 N. Freedman, “Bistatic radar system configuration and evaluation,” Raytheon Company,  Independ. Dev. 
 2, pp. 111–115,   April 1962. (Reprinted in Kovaly.15) 15. 
 Time Domain.  Most commercially available GPR systems use short pulses or  impulses such as the Ricker wavelet, as shown previously in Figure 21.5. The high- speed sequential sampling approach used to acquire RF waveforms produces a low  ch21.indd   21 12/17/07   2:51:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Although this is a rather simple example of a "complex" target, it is complicated  enough to indicate the type of behavior to be expected with practical radar targets.  The radar cross sections of actual targets are far more complicated in structure than the . i I  simple two-scatterer target. 
 Errors in the array spacings produce phase errors which generate amplitude ripples and delay nonlinearities. Since many paths exist at a given frequency, these delay and am- plitude errors tend to average out. Because of the averaging of the phase errors, the best delay linearity is achieved when the maximum number of grating lines is used. 
 Applebaum, “Cassegrain systems,” IRE Trans ., vol. AP-9, pp. 119–120,  January 1961. 
 E. Filer and J. Hartt, “COBRA DANE wideband pulse compression system,” IEEE EASCON  ’76,  1976, pp. 
 3.8. In channel A the signal  is processed as in the simple CW radar of Fig. 3.2. 
 Any one of a number of transmitting-tube types might be used as the power amplifier.  These iticlirde thc triode, tetrode, klystron, traveling-wave tube, and the crossed-field amplifier.  Pulse  Duplexer amplifier  '; "c  TI ompljfier ,~~ld I I  detector Mix  Figure4.5 Block diagram of MTI radar with  power-amplifier transmitter. 
 PRESS THESE OSCILLATIONS COMPLETELY (OWEVER  SINCE THIS PARTICULAR OSCILLATION DEPENDS ON ELECTRON VELOCITY  WHICH IN TURN DEPENDS ON BEAM VOLTAGE  THE PROBLEM IS AVOIDED BY THE USE OF MOD 
 In contrast to the lens,  which is placed between the radar and the test object, the radar and the test object  remain on the same side of the reflector, as shown in Figure 14.23. The reflector is  typically an offset paraboloid, meaning the paraboloidal surface does not include the  vertex of the generating parabola. This permits the feed that excites the reflector to be  placed out of the beam reflected toward the target. 
 13.3. The changes in clutter statistics  must be accounted for in the detector design, else the large signal-to-clutter ratios required of a  conventional threshold detector might negate any benefit of the shortened pulse. As mentioned  previously, a radar with a very short pulse (or narrow beamwidth) might prove to be worse  than one with a longer pulse (or a wider beamwidth) because of the change in clutter  statistics. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft.  MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 identification methods such as JTIDS, IFF, and RF tagging that can be unique. 
 Trunk, G. V.: Comparison of th~ Collapsing Losses in Linear and Square-law Detectors, Proc. IEEE,  vol. 
 These are discussed in the paragraphs which follow. TABLE 17.3 Discrete Clutter Model Radar cross section, m2 106 105 104Density, per mi2 0.01 0.1 1 . Guard Channel. 
 POLAR CORRELATION RATIO QHV   \  %H %V  \   % H%H   % V%V       ,INEAR DEPOLARIZATION RATIO ,$2     :CX V    :CO H     :H AND :V ARE THE MEASURED REFLECTIVITIES OF THE HORIZONTAL AND VERTICAL CO 
 Note:  In MTI, a single value of CA will be obtained, while in doppler radar the value  will generally vary over the different target doppler filters. In MTI, CA will be equal to MTI  improvement factor if the targets are assumed uniformly distributed in velocity. See also:  MTI  improvement factor. 
 TYPE  TRACKING RADARS CAUSED BY HIGH 
 Output ratings vary from 14orless toover 1200 volts, and from 30ma to5amp, with any combination oftwo, three, orfour atatime. Weights vary from 5lb,foratotal output of20watts, to26lb,foranoutput of400 watts. Efficiencies range from 40percent to60percent. 
  /THER .,&- WAVEFORMS THAT HAVE BEEN UTILIZED IN RADAR INCLUDE THE NONSYM 
 Each receiver site  consists of an interferometer antenna to obtain an angle measurement in the plane of the fan  beam. There are three sets of transmitter-receiver stations to provide fence coverage of the  southern United States.  The CW radar, when used for short or moderate ranges, is characterized by simpler  equipment than a pulse radar. 
 Keller, “Airborne measurements of the ocean radar  cross section at 5.3 GHz as a function of wind speed,” Radio Sci ., vol. 21, pp. 845–856, 1986. 
 N. P.: Bright Radar Displays Employing Direct-View Storage Tubes, Conference on Air Traffic  Control S_rstems Engineering and Design, London, Mar. 13-17, 1967, IEE Conference Publication no. 
 ~ Axis of m11ror movement  Movable  .. --plonor  twist reflector RADAR ANTENNAS 243  Figure 7.13 Geometry of the polarization­ twist mirror-scan antenna, using a polar­ ization-sensitive parabolic reflector and a  planar polarization-rotating twist reflector.  Scanning of the beam is accomplished by  mechanical motion of the planar twist­ reflector. 
 II (a) in a Fortress [ 8] and (b) in a Warwick [ 12]. Figure 2.13. Indicating units, with gain, brilliance, focus and range controls (left to right, viewed from the front), (a) type 6; (b) type 6 A; (c) type 96 [ 7].Airborne Maritime Surveillance Radar, Volume 1 2-15. 
 !      !          !   ! !     !           
 Accurate long-term forecasting of the  precise location and level of severity of these phenomena, through data assimilation  and numerical weather prediction techniques, is beyond the present state of the art.  Operational radars, however, can detect these phenomena and provide local warn - ings of approaching severe events; they can also detect the rotating mesocyclones  in severe storms that are precursors to the development of tornadoes at the Earth’s  surface.134 Ground-based coastal and airborne radars can also measure the severity  of approaching hurricanes and define their most intense landfall positions for evacu - ation warnings.135,136 Tornado Detection.  A single doppler radar can measure only the radial compo - nent of the vector wind field. 
 The various amplifier transmitters, however, are generally capable of  higher power than the magnetron oscillator. Amplifiers are of greater inherent stability, which  is of importance for MTI and other doppler radars, and they can generate more conveniently  than can power oscillators the modulated waveforms needed for pulse-compression radar.  Power oscillators, therefore, are likely to be found in applications where small size and  portability are important and when the stability and high power of the.amplifier transmitter  are not required. 
 NIQUES TO DETECT AND EVALUATE MOVING TARGETS  4HE *OINT 34!23 3!2 MODE INVOLVES A CLASSICAL SINGLE 
 7-11, 1987. 51. Lord, D. 
 Each  of the interferometer ports produces a (complex-valued) range-doppler “image” that  could be called a “SAR” image, since it was formed from a coherent sequence of  pulses, and the subsequent complex pair-wise combining of these images with the  proper relative complex weighting to null the clutter can be considered as an InSAR  process. On the other hand, to avoid confusion with the type of interferometric SAR  that is used for target height measurement, the Joint STARS team typically refers to  their process as “Clutter Suppression Interferometry” or simply “CSI”.‡ Barbarossa and Farina43 show that, by using multiple subapertures, detection and  repositioning of moving targets can be considerably improved, in an extension of the  real-beam Displaced Phase-Center Antenna (DPCA) technique (Staudaher44). They  developed a procedure for SAR processing using an arbitrary number of subaper - tures, separated horizontally, to cancel ground clutter and image a moving target. 
 The Confirm dwell is used to manage false alerts  and provide a range measurement for target detections. The Alert and Confirm detec - tion thresholds are designed to achieve overall false alarm time equal to conventional  search (one every few minutes). Along with using the same PRF in Alert and Confirm,  the time between these dwells, or latency , should be minimized to prevent a valid Alert  detection from being eclipsed during the Confirmation dwell. 
 A dielectric around the wires is equivalent to a shortening of the  wavelength incident on the mesh. The spacing between wires appears wider, ekctrica\ly,  causing the transmission coefficient of the surface to increase. On the other hand, the total  reflecting surface is increased by the presence of ice, reducing the transmission through the  mesh. 
 The values stored in the map are milltiplied  by an appropriate constant to establish the threshold for zero-relative-velocity targets. This  eliminates the usual MTI blind speed at zero radial velocity and permits the detection of  crossing targets in clutter if the target cross section is sufficiently large.  ~hus, in Fig. 
 Allen, “A theoretical limitation on the formation of lossless multiple beams in linear arrays,”  IRE Trans ., vol. AP-9, pp. 350–352, July 1961. 
 The noise figure due to these RF losses may be derived from the definition of  Eq. (9.1 ), which is  (9.1)  The noise N0u, from the lossy RF components is kT0 Bn, and G = 1/L,.F. Therefore on substi·  tution into Eq. 
 M. Jones and J. J. 
 The synchro rotor ismatched tothedriving tube byastepdown transformer. Since the secondary circuit isalmost purely inductive (ideally itwould be precisely so), itscurrent waveform will resemble that inthe primary of thetransformer, and acurrent amplifier similar tothat driving thedeflec- tion coil ofFig. 13.44 isappropriate. 
 The frequencies  (2.7 Hz and 12 Hz) are peculiar to the specific truck that was imaged. ( Courtesy  of Northrop-Grumman Corporation ) ch17.indd   27 12/17/07   6:49:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 7.6] THE U.S. TACTICAL AIR COMMANDS 231 and issue radiotelephone instructions tofriendly fighters inaneffort to bring them into favorable positions tocounter airattacks. For defensive operations, thk sort ofcontrol isusually adequate; enemy airattacks will ordinarily bedirected atoneofafewvital areas where substantial damage can bedone. 
 The CCD, or charge coupled device, is one possibility as a shift register.  The data on the synthetic display must be refreshed at a sufficiently high rate to obtain  a Iiigh brightness and to avoid flicker. When a number of displays are used with the output  of a single radar, a dedicated minicomputer can be used at each display position for the  refresh of data so as to reduce the data-transfer rate from the radar central processor. 
 8.15 it can be seen that the array will scan over the region + 30" as the  frequency is varied from 0.968Jo to 1.035f0, wherefo is the frequency corresponding to the  broadside position of the beam. As the frequency is increased, the factor n1 = 10 applies and  the same arigular region is scanned as the frequency varies from 1.075f0 to 1. 149fo. 
 FED ARRAY &IGURE   CAN BE CONSIDERED  AS TWO END FEEDS %ACH FEED CONTROLS AN APERTURE THAT IS HALF THE TOTAL AND  THEREFORE   HAS TWICE THE BEAMWIDTH !S THE FREQUENCY IS CHANGED  EACH HALF OF THE APERTURE SCANS IN THE OPPOSITE DIRECTION 4HIS INITIALLY CREATES A BROADER BEAM WITH REDUCED GAIN !S FREQUENCY CONTINUES TO CHANGE  THE TWO BEAMS WILL EVENTUALLY SPLIT APART !T BROAD 
 If the  guide is not used to terminate in a radiator, then energy  is fed in by a small aerial stub at the start of the tube,  and taken from the far end of the tube by a similar stub.  The majority of guides used in radar equipment are of  rectangular cross-section, to ensure greatest accuracy in  design, and also, so the cynics would say, to simplify  the mathematics! The ‘arithmetic’ of this form of link  does, in fact, become quite complicated, because mathe-  matical analysis shows that only certain types of wave-  forms can be propagated along metallic wave-guides,  and each of these wave-types, moreover, is characterized  by a certain distribution of electromagnetic field over  the cross-section. The velocity of the waves is different  from that in free space, so the wavelength in the tube is  somewhat different from the length in space, and this  . 
 MAIL REQUEST DAVIDLYNCHJR IEEEORG AND CARLOKOPP IINETNETAU   # +OPP  h!CTIVE ELECTRONICALLY STEERED ARRAYS v   HTTPWWWAUSAIRPOWERNET   *OINT !DVANCED 3TRIKE 4ECHNOLOGY 0ROGRAM  h!VIONICS ARCHITECTURE DEFINITION  v 53 $O$  PUBLIC RELEASE  UNLIMITED DISTRIBUTION AND USE  PP           $ %LIOT ED    (ANDBOOK OF $IGITAL 3IGNAL 0ROCESSING  3AN $IEGO  #! !CADEMIC 0RESS     PP n  n  n  n   , 4OWER AND $ ,YNCH  h0IPELINE (IGH 3PEED 3IGNAL 0ROCESSOR v 53 0ATENT      .   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°{Î   , 4OWER AND $ ,YNCH  h3YSTEM FOR !DDRESSING AND !DDRESS )NCREMENTING OF !RITHMETIC 5NIT  3EQUENCE #ONTROL 3YSTEM v 53 0ATENT        , 4OWER AND $ ,YNCH  h0IPELINED MICROPROGRAMMABLE CONTROL OF A REAL TIME SIGNAL PROCESSOR v  IN )%%% -ICRO #ONFERENCE  *UNE   P    $ ,YNCH  h2ADAR SYSTEMS FOR STRIKEFIGHTER AIRCRAFT v PRESENTED AT  !/#  4HIRD  2ADAR%7  #ONFERENCE 0ROCEEDINGS  5NCLASSIFIED PAPER IN CLASSIFIED PROCEEDINGS AVAILABLE FROM AUTHOR BY  REQUEST  &EBRUARY n     $ ,YNCH   )NTRODUCTION TO 2& 3TEALTH   2ALEIGH  .# 3CI4ECH 0UBLISHING    PP n    n  n  n n  n   $ ,YNCH ET AL  h!DVANCED AVIONICS TECHNOLOGY v %VOLVING 4ECHNOLOGY )NSTITUTE 3HORT #OURSE  .OTES  .OVEMBER   3 3 "LACKMUN   -ULTIPLE 4ARGET 4RACKING WITH 2ADAR !PPLICATIONS   $EDHAM  -! !RTECH (OUSE     PP n  n   $ ! &ULGHUM AND $ "ARRIE  h2ADAR BECOMES A WEAPON v  !VIATION 7EEK  3PACE 4ECHNOLOGY    PP n  3EPTEMBER     )MAGE #OURTESY 2AYTHEON #OMPANY  CLEARED FOR PUBLIC RELEASE   
 Interms ofEoand S~,thecross section udefined inSec. 2.3isgiven by (1) 3-2. Rayleigh Scattering from aSmall Sphere.—As anillustration of the use ofthis equation, weshall derive the Rayleigh law forthe case 1Sections 3.1-3.4 and3.6by.!.J,F,Siegert, 3,5byL,X.Ridenoar, and3.7b.v 11.H.Johnson. 
 J: Synthetic Aperture Radar; chap. 23 or" Radar Handbook," M. I. 
 TO 
 6.13). The axis ofthe conical scan was aligned with the guns sothat only point-blank fire with nolead was possible. Thk was done because the lead required incountering theusual nightfighter approach isnegligible. 
 2009 ,18, 2221–2229. [ CrossRef ] 27. Gonzalez, R.; Woods, R. 
 PORT MEASURING THE DIFFERENCE BETWEEN THE SEA LEVEL AND THE TOP SURFACE OF FLOATING ICE FREEBOARD  "ECAUSE THE DENSITY OF ICE IS RELATIVELY WELL 
 FIELD MODEL )T IS PROBABLY MORE  RELEVANT TO THE LONGER 
 In this chapter, the radar antenna will be considered either as a transmitting or a receiving  device. depending on wliicli is more convenient for the particular discussion. Results obtained  for one may be readily applied to the other because of the reciprocity theorem of antenna  theory.'  CHAPTER SEVEN RADAR ANTENNAS 7.1ANTENNA PARAMETERS1.2 Thepurposeoftheradarantenna istoactasatransducer between free-space propagation and guided-wave (transmission-line) propagation. 
 Other electronic phase shifters. In addition to the ferrite and diode devices, there have been  other techniques suggested for electronically varying the phase shift. The traveling-wave tube  296INTRODUCTION TORADAR SYSTEMS Waveguide,Nonrecipracal- Phas~- €I~ent-with7 palamers coilandyokes:; Figure8.13 Oual-mod~ reci­ procalphaseshifterconfigura­ tion.(From IVhickt'f (llld rOl/lliJ. 
 3.8,  McGraw-Hill Book Company, New York, 1947.  29. Blacksmith, P., Jr., R. 
 Several forms of data analysis and display are accessible, but perhaps the most use - ful are the maps of (i) Excess Power and (ii) Optimum Frequency . The Excess Power  parameter is constructed as follows. Consider a specific target whose RCS is known  or estimated as a function of frequency. 
 532 533. July. 1974. 
 Inthefollowing weshallderivetheoptimum formofthesecond~detector law.26•43 Assume thatthereareIIindependent pulseswithenvelope amplitudes VJ,V2'.••,Vnavailable fromtheradarreceiver. Theproblem consists indetermining whether theseIIpulsesaredueto signal-plus-noise orwhether theyareduetonoisealone.Theprobability-density function for theenvelope ofIIindependent noisesamples istheproductoftheprobability-density function foreachsample. or n Pn(lI,I'd=nPn(vd i=I(10.33) Theprohahility-density function forithnoisepulsePn(Vj)isgivenbyEq.(2.21),rewritten (2.21) where 1';istheratiooftheenvelope amplitude Rtothermsnoisevoltaget/Ji,/2.Likewise, the probability-density function fortheenvelope of"signal-plus-noise pulsesis n P.•(II,Vi)=nPs(Vi) i=1(10.34) Theprobability-density function forsignal-plus-noise, Ps(Vi), IStheRicedistribution of Eq.(2.27) (2.27) (10.35)wherea=ratioofsignal(sine-wave) amplitude tormsnoisevoltageandIo(x)=modified Besselfunction ofzeroorder.Thedetection processisequivalent t<.-determining whichofthe twodensityfunctions [Eq.(10.33)or(10.34)]morecloselydescribes theoutputofthereceiver. 
 Leith, E. N.: Optical Processing Techniques for Simultaneous Pulse Compression and Beam Sharp-  ening, IEEE Trans., vol. AES-4, pp. 
 13.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 Additional scan angles may be simulated by exciting other modes. The waveguide  dimensions are chosen so that a radiating element or element placed in the waveguide  sees mirror images in the walls of the waveguide that appear to be at the same spacing  as the array to be simulated. Both rectangular and triangular arrays may be simulated,  as shown in Figure 13.15. 
 TRAFFIC CONTROL RADARS OPERATE WITH TWO FREQUENCIES SPACED WIDE ENOUGH APART IN FREQUENCY TO INSURE THAT TARGET ECHOES ARE DECORRELATED AND  THEREFORE  INCREASE THE LIKELIHOOD OF DETECTION. £°£ä  2!$!2 (!.$"//+  2EDUCED %FFECTIVENESS OF (OSTILE #OUNTERMEASURES  !NY MILITARY RADAR THAT IS SUC 
 Although the usual SAR optical  processing provides dechirping (matched filtering) of the linear FM pulse-compression  wavcform, tlie cliirp niodulation of the transmitter is accomplished as in other pulse-  compression radars.  Other aspects of SAR. The SAR has been described as a side-lookirtg rudur wiih the antenna  beam directed perpendicular to the path of the vehicle such that the dopplel. 
 The S-193 zone of access was 48º forward and 48º to  either side of the spacecraft ground track. For selected measurements, the beam was  pointed in the along-track direction to fixed angles of 0º, 15.6º, 29.4º, 40.1º, and 48º,  with sufficient dwell time at each angle to permit averaging to achieve approximately  5% precision. RadScat data collected over the Amazon rain forest suggested that the  uniformity of the observed backscatter would be a stable calibration reference for  space-based radars, which has since been validated as a standard technique.132 SASS , the Seasat-A Satellite Scatterometer,133,134 was the first space-based radar  designed specifically to measure oceanic winds. 
 The third bistatic RCS region, forward scatter, occurs when the bistatic angle approaches 180°. When P = 180°, Sicgcl33 showed, based on physical optics, that the forward-scatter RCS, crF, of . a target with silhouette (or shadow) area^4 is cr^r = 4TTv42/X2, where X, the wave- length, is small compared with the target dimensions. 
 Thus, one should be careful in  using mean values for radar design; the median values are more representative. Billingsley17 presented his results both in terms of mean values and median values.  Here, we report only the median values because they tend to be more meaningful for  radar design than the values distorted by occasional strong targets. 
 It lias been found4 that tlie backscatter  is more sensitive to wirid direction at the higher radar frequencies than at the lower frequencies,  that horizontal polarization is more sensitive to wind direction than is vertical polarization,  that the ratio of rrO measured upwind to that measured downwind decreases with increasing  grn7irig atigle and sen stittc. :trlil tI1:tt at UIiF the backscatter is practically insensitive to  wind direction at grazing atigles greater than ten degrees.  Wlietl viewing the sea at or near vertical incidence the backscatter is greatest with a calm  sea a~id decreases will1 increasing witid. 
 G. H. Pettengill, P. 
 Harger, Synthetic Aperture Radar Systems : Theory and Design , New York: Academic  Press, 1970.  9. R. 
 SPACE VALUE $IFFRACTION %NERGY TENDS TO FOLLOW ALONG THE CURVED SURFACE OF AN OBJECT 4HE  DEGREE OF REFRACTION IS DEPENDENT UPON THE POLARIZATION OF THE PROPAGATING WAVE AND THE SIZE OF THE DIFFRACTING OBJECT RELATIVE TO THE WAVELENGTH $IFFRACTION IS THE PROCESS BY WHICH THE DIRECTION OF PROPAGATING RADIATION IS CHANGED SO THAT IT SPREADS INTO THE GEOMETRIC SHADOW REGION OF AN OPAQUE OBJECT THAT LIES IN THE RADIATION FIELD )N THE EARTH 
 352 THEMAGNETRON ANDTHEPULSER [SEC. 106 magnetron-magnet combination isnow asmall fraction ofthe weight of the pulser required todrive it. The weight ofmagnetrons and their magnets has thus ceased tobeacritical design consideration. 
 228-9,  March, 1973.  JOO. Hering, K. 
 One of the factors that is often misleading is the usual picture of an array as a single  radiating face of relatively modest size. A single array antenna can scan but a limited sector;  ± 45° in each plane is perhaps typical. Four or more faces might therefore be necessary for  hemispherical coverage. 
 Sincethepulsepackettravelsatthespeedoflight.thereceiving beam sometimes mustbescanned morerapidlythanpossible bymechanical means.Thisiscalled pI/1st'clrasi"g.Ifthereceiving antenna usesabroadfixedbeam.theproblem ofpulsechasing is alleviated. However. thesmallerefrective antenna aperture associated withthebroadreceiving beamresultsinlessechosignal.Thismustbecompensated bygreatertransmitter power.In short.theuseofbistaticradartoobtainotherthanfencecoverage usuallyresultsinmore complicated andlessefficient systems.. 
 CLUTTER POWER RATIO AT  THE OUTPUT OF THE CLUTTER FILTER DIVIDED BY THE SIGNAL 
 SHAPED  FEATURES WHOSE PHASE REMAINS STABLE OVER VERY LONG TIME SCALES 4HESE SO 
 .. 4W 12.7 Automatic Frequency Control. 453 12.8 Protection against Extraneous Radiation. 
 Figure 2.22 also indicates that for probabilities of detection  greater than about O.JO. a greater signal-to-noise ratio is required when the fluctuations are  uncorrelated scan to scan (cases I and 3) than when the fluctuations are uncorrelated pulse to  pulse (cases 2 and 4). In fact. 
 - 4HERE ARE THREE MAIN MODULATION TECHNIQUES TIME DOMAIN  FREQUENCY DOMAIN  AND PSEUDO 
 'fhus a low-noise receiver might not always be the obvious selection.  if properties otlier than sensitivity are in~portant.  9.5 DISPLAYS  The purpose of the display is to visually present in a form suitable for operator interpretatiorl  and action the information contained in the radar echo signal. 
 POWER RATIO IS  INVERSELY PROPORTIONAL TO K  7EATHER RADARS TYPICALLY USE DIGITAL SIGNAL PROCESSING TECHNIQUES TO IMPLEMENT  CLUTTER FILTERS THAT SUPPRESS NEAR ZERO VELOCITY CLUTTER ECHOES 4HESE FILTERS MAY BE  IMPLEMENTED USING EITHER A TIME DOMAIN CLUTTER FILTER APPLIED TO THE ) AND 1 RADAR VIDEO DATA ONE FORM OF WHICH IS SOMETIMES CALLED A  DELAY LINE CANCELER  FROM ITS EARLY  ANALOG IMPLEMENTATION  TO SUPPRESS THE ZERO VELOCITY GROUND CLUTTER COMPONENTS OR A FREQUENCY DOMAIN DOPPLER POWER SPECTRUM A DIGITAL hFILTER BANKv  TO ACHIEVE THE SAME EFFECT  4HE TIME DOMAIN FILTERS FOR MECHANICALLY SCANNED WEATHER RADARS ARE USUALLY  INFINITE IMPULSE RESPONSE ))2  FILTERS WITH NARROW  BUT ADJUSTABLE  WIDTHS UP TO A FEW MS AND HAVING SUPPRESSION LEVELS OF n D" AND VERY STEEP TRANSITION REGIONS   4HESE TIME DOMAIN FILTERS WITH A FREQUENCY NOTCH CENTERED AT ZERO VELOCITY FREQUENCY  . £°£{  2!$!2 (!.$"//+  WILL ALSO SUPPRESS WEATHER ECHO POWER  THAT MAY EXIST IN THE SAME VELOCITY REGION AND  BIAS ALL THE ESTIMATES OF REFLECTIVITY  VELOCITY  AND WIDTH 3PECTRAL DOMAIN CLUTTER FILTERS IMPLEMENTED BY A DISCRETE &OURIER TRANSFORM $&4    ON THE OTHER HAND  SUPPRESS THE NEAR ZERO CLUTTER COMPONENTS IN THE FREQUENCY DOMAIN  AND MAY INTERPOLATE THE REMAINING SPECTRUM ACROSS THIS REGION TO RETAIN MOST OF THE UNDERLYING SIGNAL OR NOISE  SPECTRAL INFORMATION !N ALTERNATIVE FREQUENCY DOMAIN TECHNIQUE FOR THE .EXRAD RADAR SEPARATELY MODELS THE CLUTTER AND WEATHER SIGNAL AS GAUSSIAN 
 Often, in the past, the assumption has been made that the returns from clutter have a  gaussian power spectral density, which may be characterized by its standard deviation  sv and mean velocity mv, both in units of m/s.6 Using this gaussian model, each of the  spectral lines in Figure 2.11 will be convolved with the spectrum:  S ff m G ff f( ) exp( )= ⋅ −−   1 2 22 2πσ σ (2.4) This spectrum is normalized to have unit power, and the velocity parameters have  been converted to Hz using the doppler equation:  mm fv fv=⋅ =⋅2 2λ σσ λ (2.5) FIGURE 2.11  Pulse transmitter spectrum ch02.indd   11 12/20/07   1:43:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 RESOLUTION IS THE RESULT 4HE DESIRED SPATIAL SPECTRUM PATTERN IS OBTAINED AS SIMPLY THE INVERSE OF THE ADAPTED PATTERN !S 'ABRIEL POINTED OUT  THERE IS NOT A TRUE ANTENNA PATTERN BECAUSE THERE IS NO LINEAR COMBINATION OF THE SIGNALS FROM AN ARRAY THAT COULD PRODUCE SUCH A PEAKED SPATIAL PATTERN )T IS SIMPLY A FUNCTION COMPUTED FROM THE RECIPROCAL OF A TRUE ADAPTED ANTENNA PATTERN 3UPERRESOLUTION AND ADAPTIVE ANTENNAS FOR JAMMER CAN 
 Subarrays may be formed, each with only one phase control and of a size such that its beam width includes all the scan angles. Alternatively, a small phased array could be placed in the focal region of a large reflector to scan the narrow beamwidth of the reflector over a limited scan angle. Scanning of Arrays Phase Scanning. 
 Palamutcuoglu, 0., J. G. Gardiner, and D. 
 Geophys. Res ., vol. 100, pp. 
 It follows that through continuous display(continuous because of the persistence of the CRT screen and the pulserepetitionrate)ofthepositionsoftargetsonthePPI,theirmotionsrelativetothe motion of the reference ship are also displayed. In summary, the indicator of this basic radar system provides the means for measuring and displaying, in a useful form, the relative bearings anddistances to targets from which reﬂected echoes may be received. Indisplaying the positions of the targets relative to the reference shipcontinuously, the motions of the targets relative to the motion of thereference ship are evident.. 
 In the daylight hours, the F region  sometimes manifests two component layers, especially in summer. The Fl region lies  between 130 and 200 km and, like the E region, is directly dependent upon solar  radiation; it reaches maximum intensity about 1 h after local noon. The F2 region is  variable in both time and geographical location. 
 TION OF SILICON BIPOLAR POWER DEVICES 4HE TWO FINAL OUTPUT DEVICES AND THE EIGHT DRIVER DEVICES ARE  7 TRANSISTORS CAPABLE OF OPERATING UP TO A  DUTY CYCLE OVER THE   
 The relative phase excitation caused by these feeds is a known function of frequency. In these cases, the computer must provide a correction based on the location of the element in the array and on the frequency of operation. For a large array with thousands of elements, many calculations are required to determine the phasing of the elements. 
 TIONS MAY BE DERIVED BY EXPANDING THE WAVE EQUATION %Q   IN A POWER SERIES OF THE WAVENUMBER  K  (IGHER 
 Smith, and C. E. Grove: L-band T/R Module for Airborne Phased Array,  J\ficroware J .. 
 ING ISSUESWOULD SUFFER AS A CONSEQUENCE 4HANKS TO THE MISSION DESIGN  HOWEVER  -AGELLAN IMAGE QUALITY IS SURPRISINGLY CONSISTENT  POLE TO POLE 4HE REASONS PROVIDE  AN IMPORTANT OBJECT LESSON 3INCE THE -AGELLAN RADAR WAS OPERATED IN BURST MODE  IT WAS CONVENIENT AS WELL  AS NECESSARY  PRIOR TO EACH BURST TO SET THE MODE PARAMETERS  WHICH  IN GENERAL  VARIED  FROM BURST TO BURST #RITICAL PARAMETERS INCLUDED 02&  RANGE GATE  BURST LENGTH  BURST  PERIOD  AND SPACECRAFT ROLL 4HE PARAMETER FILES WERE PREPARED IN ADVANCE  BASED ON THE DATA COLLECTION GEOMETRY  AND TURNED INTO COMMANDS TO BE GENERATED BY THE RADAR MAP 
 SHIFT CHANGE WITH DIRECTION THAT IS PRESENT FOR AN ANTENNA ARRAY AND RESULTS IN THE ANTENNA PATTERN &OR GROUND ECHO  THE DISTANCE IS DOUBLED  SO THE PATTERN OF AN ECHOING PATCH OF LENGTH  , HAS LOBES OF WIDTH  K, 4HIS COMPARES WITH  K,  FOR AN ANTENNA OF THE SAME CROSS 
 Syst. 1999 ,35, 1240–1252. [ CrossRef ] 16. 
 LIMITED FOOTPRINT (ENCE  THE RECEIVED POWER TENDS TO MAINTAIN THE LEVEL CORRESPONDING TO THE PEAK OF THE INITIAL RESPONSE &IGURE   4HE PULSE 
 MOVING BIRDS AND LOW CROSS 
 This procedure, together with adjustment ofthe regulator onthe tight side ofthedip, helps notonly inclearing upthetroubles mentioned above, but also inincreasing the interval between regulator adjustments, and inreducing thewear ofthe carbon disks. The carbon-pile regulator isaffected bymoisture. Moisture inthe carbon pile materially reduces the resistance, and frequently when a motor-alternator isstarted after having stood forsome time inanatmos- phere saturated with water vapor the output voltage ishigh—approxi- mately 135 to145 volts. 
 4.2) and the increased spread of the clutter spectrum. The  Moving Target Detector, described in Sec. 4.7, is an example of an MTI radar designed  specifically to cope with the special problems of precipitation clutter. 
 CONCLUSION 167  make a weapon too great for any one man or any one  nation to hold. Although the people and even the  scientists are reluctant to realize what has happened,  the baby of radar, born in the nineteen-thirties in Slough,  has risen from that despond to become a giant. In his  youth he saw valiant war service. 
 Therehavebeenotherkindsofferritephaseshiftersdcvelopt.:d overtheyearsbasedondifferent principles oronvariations ofthosedescriht.:d ahove. Although theabovephaseshifterswerediscussed primarily aswaveguidc devices,somcof thcmmayheimplemented incoax,helicalline,andstriplinc. JJ TheferriteFaraday rotator,whichwasmentioned aboveasbeingapartofthedual-modc phaseshifter,alsohasbeenappliedasanelectronic phaseshifter.33.3MItistheequivalent ofthe mechanical Foxphaseshifter.39Otherexamples of phase shiftersareahelicalslow-wave structure eithersurrounded byorsurrounding aferritetoroid,40.41 atransversely magnetized slahofferriteinrectangular waveguide,42.43 abuckingrotatorphaseshifter,"" circularpolari­ zationbetween quarter-wave plates,44 areciprocal, polarization-insensitive phaseshifterfor reftectarrays,45 wideband phaseshifters,46 andphaseshiftersthatoperateatUHF:nFerritcs havealsobeenusedincontinuous aperture scanning whereaphasechangeisprovided across anaperture withoutsubdividing itintoseparate elements. 
 Sampled-Data Operation.2'4'6 To overcome the limitation of tying up an il- luminator for the duration of a semiactive engagement, a single radar can be time- shared among several missiles. This generally implies a phased array radar, al- though mechanically scanned track-while-scan (TWS) radars can provide this option in some cases. The advent of phased array radars permitted a single transmitter to illuminate many targets by sequentially stepping its agile beam from one target to the next. 
 It places a virtual short circuit across the capacitor bank to transfer the stored energy  by means of a switch which is not damaged by the momentary short-circuit conditions. The  name is derived from the analogous action of placing a heavy conductor, like a crowbar,  directly across the capacitor bank. Hydrogen thyratrons, ignitrons, and spark-gaps have been  used as switches. 
  
 M .. and C. N. 
 SCALE ROUGHNESS DECREASES THE POWER OF THE PULSE REFLECTED BACK TO THE ALTIMETER (ENCE  FOR WIND SPEEDS OF MORE THAN ABOUT TWO KNOTS  73 IS INVERSELY RELATED TO MEAN WAVEFORM POWER )N PRACTICE  THE INFLECTIONS OF THE IDEALIZED FLAT 
 Van Baelen and A. D. Richmond,  “Radar interferometry technique: Three-dimensional wind  measurement theory,” Radio Sci., vol. 
 (ii) The InSAR results are validated by 56 leveling benchmarks. (iii) We study the inﬂuence of natural conditions and human activities on land subsidence and their interrelationships. 2. 
 46. J. Frichel and F. 
 ANGLE CLUTTER QUITE WELL 4HE DECAY LAW FOR VERY LOW 
 CALLED FOUR 
 Remote. Sens. Lett. 
 29, no.3, pp. 834–863, July 1993. ch08.indd   42 12/20/07   12:52:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 COOLED  AND THE MEASURED EFFICIENCY IS GREATER THAN  WHEN THE MODULE IS OPERATING AT AN  AVERAGE DUTY CYCLE -ODULE POWER GAIN IS GREATER THAN  D" ! CIRCULATOR IS USED ON THE OUTPUT PORT TO PROTECT THE  7 DEVICES FROM ANTENNA 
 A new algorithm for surface deformation monitoring based on small baseline di ﬀerential SAR interferograms. IEEE T rans. Geosci. 
 ERS  %VEN WITH 34!0  THE NON 
   PP n  -AY   2 " $YBDAL AND # / 9OWELL  h6(& TO %(& PERFORMANCE OF A  
 The sizes ofL,,L,,and R,depend upon how quickly itis desired tobring thetail ofthepulse down tozero once thegrid drive has been removed, and also onhow much energy one iswilling towaste in these elements during thepulse. There exists anupper limit tothe size ofthe coupling condenser, because avery large capacity would take longer torecharge fully after a pulse. Given afixed pulse rate and recharging impedance, anincrease incoupling capacity will beaccompanied byanincrease inthe no-load tofull-load voltage ratio. 
 S., Jr.: Mutual Impedance Effects in Large Beam Scanning Arrays, IRE Truti.~., vol. AI'-8,  pp. 276-285. 
 Half power and 71 percent ﬁeld strength correspond to -3 dB; quarterpower and 50 percent ﬁeld strength correspond to -6 dB. Figure 1.2 - Free space radiation pattern.frequencyspeed of radar waves wavelength--------------------------------------------------= frequency300 000 km, ondsec---------------------------------0.000032 km cycle---------------------------------- - ÷ frequency 9375megahertz= = . 5The radiation diagram illustrated in ﬁgure 1.3 depicts relative values of power in the same plane existing at the same distances from the antenna orthe origin of the radar beam. 
 Table 8.1shows the comparison between the different centimetric systems in use with Coastal Command for long range surveillance at that time. 8.1.2 ASV for Coastal Command strike aircraft and FAA Smaller 3 cm ASV systems were also developed in the UK, for use in Coastal Command strike aircraft and the Fleet Air Arm (FAA). These ASV systemsincluded the following: ASV Mk. 
 O'Hara, F. J., and G. M. 
 Measurement uncertainty result from:   - Imprecise measurement equipment   - Quantization errors   - Noise  - Signal distortion.   For an example a sine wave o scillation with be analyzed.   5.1 Measurement Accuracy and Sine Wave Oscill ations   As shown in Figure 5.1, when one observes a sine wave, with superimposed noise n(t), so differs  the observed amplitude from the true amplitude around  € ΔU=n(t)  € u(t)=U0sin(ωt+ϕ0)+n(t) (5.1)    Figure 5.1  Sine wave oscillation with superimposed noise. 
 R., and W. W. Shrader: MTI Performance Caused by Limiting, EASCON '68 Record,  Supplement to IEEE Trans, vol. 
 Thelargedoppler shiftsatmillimeter wavelengths, however, cansometimes result intheechosignalbeingoutsidethereceiverbandwidth, whichcomplicates thereceiverdesign. Also,thelargedoppler frequencies atmillimeter wavelerigths causetheblindspeedsofMTI radarstoappearatlowervelocities thanatmicrowaves, anundesirable property. Thus,afrustrating paradox ofthemillimeter-wavelength regionisthatsomeofits claimed goodpointsarealsoitsweaknesses. 
 Giannini. R. J., J. 
 32. Li, T.: A Study of Spherical Reflectors as Wide-angle Scanning Antennas, IRE Tru11s., vol. AP-7,  pp. 
 It performs doppler . 140 INTRODUCTION TO RADAR SYSTEMS  filtering on a single spectral line of the pulse spectrum. (A radar which employs multiple pulse  repetition frequencies to avoid blind speeds is usually classed as an MTI if its average prf  would cause blind speeds. 
 ANCE  ETC  OVER THE ENEMY IN A GIVEN SITUATION %-#/. PERMITS ESSENTIAL OPERATIONS WHILE MINIMIZING THE DISCLOSURE OF LOCATION  IDENTIFICATION  FORCE LEVEL  OR OPERATIONAL INTENTIONS TO ENEMY INTELLIGENCE RECEPTORS  )T INCLUDES THE AUT HORIZATION TO RADIATE  THE  CONTROL OF RADIATION PARAMETERS SUCH AS AMPLITUDE  FREQUENCY  PHASE  DIRECTION  AND  TIME  THE PROHIBITION OF RADIATION  AND THE SCHEDULING OF SUCH ACTIONS FOR ALL UNITS AND  EQUIPMENT OF A COMPLEX  4HE ON 
 DEFINED ANGULAR SPACING &OR A GRID WITH SUPPORTS  AND ASSOCIATED ERRORS  A DISTANCE  S APART  THE GRATING LOBE APPEARS AT   P   ARCSINSK     4HE GRATING LOBE AMPLITUDE DEPENDS ON THE DEPTH OF THE DISTORTION &IGURE     AND IS TYPICALLY  'RATING,OBE  ¤ ¦¥³ µ´PE L   WHERE D IS THE DEPTH OF THE CUSP &EED $ISPLACEMENT  4HE PERMISSIBLE TOTAL ERROR IN THE OVERALL FEED 
 Radar Conf. Rec ., 1975  pp. 396–401. 
 inany given case. 3However, wemay aswell lump together theeffect ofthedetector, thecathode-ray- tube modulation characteristics, the screen characteristics, and those of the eye, and admit that nobrief discussion ofthese factors ispossible. Inmost cases one has torely onexperience; that istosay, one has to design bymaking relatively short extrapolations from previous practice, orbymaking preliminary tests under conditions approximating those selected. 
 Naval Research Laboratory for over 30 years. Before that he was involved in advances in radar while at the MIT Lincoln Laboratory, the Institute for Defense Analyses, and the Research Division of Electronic Communications, Inc. He is the author of the popular McGraw-Hill textbook Introduction to Radar Systems , now in its third edition, the editor of Radar Applications , as well as being a former editor of the Proceedings of  the IEEE . 
 The Gotcha public release dataset is used to verify our aspect entropy extraction methods at the pixel and target levels. The result shows that the aspect entropy of pixels and targets can be extracted from CSAR data. Aspect entropy of pixels can be used to discriminate between isotropic and anisotropic scattering. 
 (4.25) and (4.26)  cannot be extended over too great a frequency range since account is not taken of any  variation in radar cross section of the individual scatterers as a function of frequency. The  leaves and branches of trees, for example, might have considerably different reflecting proper-  ties at K, band (A = 0.86 cm), where the dimensions are comparable with the wavelength, from  those at VHF (A = 1.35 m), where the wavelength is long compared with the dimensions.  The general expression for improvement factor for an N-pulse canceler with N, = N - 1  delay lines is6'  Antenna scanning rn~dulation.~~.~~-~~ As the antenna scans by a target, it observes the target  for a finite time equal to to = n$ fp = 88/8,, where n, = number of hits received, fp = pulse  repetition frequency, 0, = antenna beamwidth and 0, = antenna scanning rate. 
 DWELL STAGGER OPERATION IS CONSIDERABLY MORE DIFFICULT 4YPICALLY  PULSE 
 I mπ λ (19.17) where the ai are droplet radii, r is the density of water, and Im is the imaginary part.  Values of K1 for ice and water clouds are given for various wavelengths and tempera - tures by Gunn and East44 in Table 19.1. Several important facts are demonstrated by Table 19.1. 
 The  scattering from these two·· resonant" wave component:,; is similar to that from a diffraction  grating. The term Bragg st:.ttter is sometimes used to describe this form of scattering, by  analogy to the Bragg-scatte.- mode for the X-ray diffraction by crystals.  The velocity of a water wave (a gravity wave in deep water) is v = (g..l,.,/2n)112, where g is  the acceleration of gravity. 
 The range frequency fr may be extracted by measuring the average beat frequency; that is,  , f[h(up) + fb(down)] = f,. If fb(up) and fb(down) are measured separately, for example, by  switching a frequency counter every half modulation cycle, one-half the difference between the  frequencies will yield the doppler frequency. This assumes.fr > fd . 
 Retrieval of biophysical parameters of agricultural crops using polarimetric SAR interferometry. IEEE T rans. Geosci. 
 KM IMAGE FRAME  )TS STRIP MAPPING MODE IS BASELINED AT  
 There are two basic approaches for taking advantage of the nonlinearity of these metal  contacts. In one approach a single frequency is transmitted and a harmonic of the transmitted  frequency is received. The nature of the nonlinearity of typical contacts is such that the third  harmonic is usually the greatest. 
 197 207. hlarcll. 1973. 
 Anderson, “Limits to the extraction of information from multi-hop skywave radar signals,”  Proc. Int. Radar Conf ., Adelaide, September 2003, pp. 
 4, pp. 368-376, 1987. CHAPTER 24 HF OVER-THE-HORIZON RADAR* J. 
 Twersky, V.: On Scattering and Rdlection of Electromagnetic Waves hy Rough Surface~. IR I:."  Trans., vol. AP-5, pp. 
 LENGTH SEQUENCES HAVE A STRUCTURE SIMI 
 Apositive potential isappliedtothiscutoffelectrode atthetermination ofthepulse tocollect,orqllellclr,theremaining electron current. Thepositive potential needbeappliedfor onlyashorttime;hencetheenergyrequirements arelow.Thismethodofmodulation inwhich thed-canode-cathode voltage isappliedcontinuously andthetubeisturnedonbythestartof theRf7drive-pulse andturnedofTattileendoftilepulsebytheaidofacut-offelectrode to relllovetileclcctrons,hasheencalledd-c0l'erati01l. Itisapplicable toforward-wave Cf7As,but itisnotusuallyuscdwithbackward-wave CFAssincethevariation ofoutputpowerwitII frcqucncy ataconstant d-cvoltagethatischaracteristic ofbackward-wave tubeswouldlimit thebandwidth tobutafewpercent. 
 499-505, May, 1971. (Also available in ref. 1.)  9. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 11.6  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 the drain and source contacts, allowing the current flowing between the drain and source  to be modulated accordingly; hence, FETs are referred to as voltage controlled devices . 
 ING SOMETIMES CALLED COMPRESSION BECAUSE IT IS SIMILAR TO PHASE MATCHED PULSE COM 
 V.: GaAs FET Development-Low Noise and High Power, Microwave J., vol. 21,  pp. 39-44, February, 1978. 
 Inagroup ofbuildings, alarge proportion ofthe flat surfaces will bevertical walls, while many others aresmooth pave- ments orflat roofs. There aremany opportunities forcombinations of three flat surfaces atright angles toform corner reflectors (Sec. 3.5), which arehighly retredirect ivetargets. 
 The compensating delay must beinserted after thepoint atwhich thetrigger pulse hasleftthat channel but before cancellation. The first method istoadd the required delay either atcarrier or video frequency. Unfortunately, noelectrical delay lines areavailable which arecapable ofreproducing amicrosecond pulse with lessthan 1per cent distortion. 
 (OLLAND    P   0 )A 5FIMTSEV  h!PPROXIMATE COMPUTATION OF THE DIFFRACTION OF PLANE ELECTROMAGNETIC WAVES AT  CERTAIN METAL BOUNDARIES  0ART ) $IFFRACTION PATTERNS AT A WEDGE AND A RIBBON v  :H 4EKHN &IZ  5332   VOL   NO   PP n    0 )A 5FIMTSEV  h!PPROXIMATE COMPUTATION OF THE DIFFRACTION OF PLANE ELECTROMAGNETIC WAVES AT  CERTAIN METAL BOUNDARIES  0ART )) 4HE DIFFRACTION BY A DISK AND   BY A FINITE CYLINDER v  :H 4EKHN  &IZ 5332   VOL   NO   PP n    0 )A 5FIMTSEV  h-ETHOD OF EDGE WAVES IN THE PHYSICAL THEORY OF DIFFRACTION v 5 3 !IR &ORCE  3YSTEMS #OMMAND  &OREIGN 4ECHNOLOGY $IVISION $OC &4$ 
 SEL  THEN 2#3 MIGHT BE  M  AND A  M RANGE RESOLUTION MIGHT BE USED FOR SEARCH  &)'52%  4&4! TERRAIN MERGING   #OURTESY 3CI4ECH 0UBLISHING  .   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°Î£ AND ACQUISITION )F THE TARGET IS A PERISCOPE OR PERSON IN A LIFE RAFT THEN  M RESOLU 
 PULSE STAGGERING  AND INTERNAL 
 5.9 Block diagram of a generic transceiver module for phased array radar. 1. Low-cost circuitry: Component assembly is eliminated since complex cir- cuit configurations using both active and passive components are batch- processed on the same substrate. 
 SPHERE 4HESE FACTORS ARE MENTIONED TO EMPHASIZE THAT THEY CAN BE HIGHLY IMPORTANT IN  THE DESIGN AND APPLICATION OF A RADAR 2ADAR 4RANSMITTERS  4HE RADAR TRANSMITTER MUST NOT ONLY BE ABLE TO GENERATE THE  PEAK AND AVERAGE POWERS REQUIRED TO DETECT THE DESIRED TARGETS AT THE MAXIMUM RANGE  BUT ALSO HAS TO GENERATE A SIGNAL WITH THE PROPER WAVEFORM AND THE STABILITY NEEDED FOR THE PARTICULAR APPLICATION 4RANSMITTERS MAY BE OSCILLATORS OR AMPLIFIERS  BUT THE LATTER USUALLY OFFER MORE ADVANTAGES 4HERE HAVE BEEN MANY TYPES OF RADAR POWER SOURCES USED IN RADAR #HAPTER    4HE MAGNETRON POWER OSCILLATOR WAS AT ONE TIME VERY POPULAR  BUT IT IS SELDOM USED EXCEPT FOR CIVIL MARINE RADAR #HAPTER   "ECAUSE OF THE MAGNETRONS RELATIVELY LOW AVERAGE POWER ONE OR TWO KILOWATTS  AND POOR STABILITY  OTHER POWER SOURCES ARE USUALLY MORE APPROPRIATE FOR APPLICATIONS REQUIRING LONG 
 Although the typical radar transmits a simple pulse-modulated waveform, there are a  number of other suitable modulations that might be used. The pulse carrier might be  frequency- or phase-modulated to permit the echo signals to be compressed in time after  reception. This achieves the benefits of high range-resolution without the need to resort to a  short pulse. 
 J. Daniels, Ground Penetrating Radar , 2nd Ed. IEE Radar Sonar Navigation and Avionics  Series, London: IEE Books, July 2004. 
 (ALL    PP n  * & 2AMSEY  h,AMBDA FUNCTIONS DESCRIBE ANTENNADIFFRACTION PATTERNS v  -ICROWAVES  P    *UNE   7 - 9ARNALL  h4WENTY 
 Patent, 4, 006, 478, February 1, 1977,  filed August 15, 1958. 156. R. 
   2!$!2 $)')4!, 3)'.!, 02/#%33).'   Óx° SAMPLE RATE 4HE SINE AND COSINE SIGNALS FROM THE .#/ ARE THEN DIGITALLY MULTIPLIED  BY THE DIGITIZED )& SIGNAL )N THIS PARTICULAR EXAMPLE  THE REL ATIONSHIP BETWEEN THE ,/  FREQUENCY AND THE SAMPLING RATE WILL MAKE THE REQUIRED .#/ AND THE MULTIPLIERS BOTH RATHER TRIVIAL BECAUSE EACH REQUIRED .#/ OUTPUT VALUE IS ZERO OR  o  AND THAT SPECIAL  CASE WILL BE ADDRESSED SHORTLY &OR NOW  THIS ARCHITECTURE SUPPOSES THAT NO SUCH SPECIAL SITUATION EXISTS AND THAT A GENERAL .#/MULTIPLIER STRUCTURE IS NEEDED 4HE DESIGN OF &)'52%   $IGITAL DOWNCONVERSION IN THE FREQUENCY DOMAIN 0 
 ADDED EFFICIENCY  IS A CIRCUIT DESIGNERS TERM AND IS DEFINED BY   0!%   0/  
 Ruze showed that the radiation pattern can be expressed as  (7.31)  where G0(0. q,) is the no-error radiation pattern whose axial value (at O = 0, </J = 0) is  110(n:IJ/A)2• {) is the antenna diameter, Pa is the aperture efficiency, C is the correlation interval  of the error, and II equals sin 0. The mean square phase error Pis assumed to be gaussian. 
 A procedure is proposed aimed at both improving the range migration algorithm and imaging data from different view angles in a unified coordinate system. This provides images with the same resolution, not deformed and scaled, that can be fused quickly and accurately. The work in [ 2] also deals with the optimal processing of SAR data acquired with wide aperture, as for circular SAR systems, and in particular tackles the problem of aspect-dependent backscattering. 
 It produces a negative voltage at A’s anode, which is fed  to B’s grid and produces a positive voltage at B’s anode,  which adds itself to the original r-volt change. There  will be two very different results, depending on whether  the application of 1 volt positive will make B’s anode  go more or less than 1 volt positive.  Suppose that the effect of 1 volt positive is that A’s  anode goes 4 volt negative, making B’s grid, of course,  also go 4 volt negative. 
 The minimum  operational display area is defined as a diameter: 180 mm for ships less than 500 gt;  250 mm for ships from 500 to 10,000 gt; and 320 mm for ships above 10,000 gt. The  minimum recommended display areas for small craft radar are given in Table 22.2.  The color of radar targets and background is not mandated. 
 CIALLY IN URBAN AND SUBURBAN AREAS  CAN SIGNIFICANTLY DEGRADE 0"2 PERFORMANCE 4HIS SECTION SUMMARIZES THE PROBLEMS AND REMEDIES ENCOUNTERED BY A 0"2 EXPLOITING THESE BROADCAST TRANSMITTERS. 
 K. L. S. 
 Amein, A.S.; Soraghan, J.J. Fractional Chirp Scaling Algorithm: Mathematical Model. IEEE T rans. 
 10.17 atapoint ofhigh efficiency and low frequency stability corresponding topoint A.This can beaccomplished byintro- ducing atransformer which sets upa2-to-1 VSWR and making itsdis- tance from themagnetron such that thephase ofthis VSWR corresponds topoint A. Bymoving this transformer along theline ineither direction one-quarter wavelength, operation corresponding topoint Bcan be obtained. Incomparing the eflect ofdifferent loads corresponding to various points onthe Rieke diagram, itshould berealized that these points represent transformations that reduce the size ofacircle ofcon- stant VSWR asitscenter ismoved away from thecenter ofthediagram. 
 11.6. The amplitude distribution across the aperture as a  (11.35)EXTRACTION OFINFORMATION ANDWAVEFORM DESIGN409 spectrum andawidewaveform yieldsanarrowspectrum andboththetimewaveform andthe frequency spectrum cannotbemadearbitrarily smallsimultaneously. TherelationofEq.(11.34)isuseful,however, asanindication oftheaccuracy withwhich timedelayandfrequency maybemeasured simultaneously. 
 2.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 shifted precisely 360° or multiples thereof between pulses, which results in no change  in the phase-detector output. The blind speeds can be calculated  V kfkBr= ⋅⋅= ±λ 20 1 2, , ,... (2.1) where VB is the blind speed, in meters per second; l is the transmitted wavelength, in  meters; and fr is the PRF, in hertz. 
 BAND  AND  '(Z  4HE  )45 RECOMMENDS THAT FOR PULSE LENGTHS OF  §S OR LONGER  THE FREQUENCY ACCURACY OF  THE RESPONDING SIGNAL SHOULD BE WITHIN  o -(Z  AND FOR PULSES OF LESS THAN  §S   THE FREQUENCY SHOULD BE WITHIN  o -(Z 3WEPT FREQUENCY RACONS ARE EFFECTIVELY  OBSOLESCENT BUT ARE STILL PERMITTED 4HESE WORK BY HAVING AN INTERNAL 2& SOURCE THAT IS SLEWING IN FREQUENCY ACROSS THE ENTIRE RADAR BAND WITH A SAW 
 71.Siebert, W.M.:SomeApplications ofDetection TheorytoRadar,IRENatl.Conv.Record,vol.6, pt.4,pp.5-14,1958. 72.Hansen, V.G.,andA.J.Zottl:TheDetection Performance oftheSiebertandDicke-Fix CFARRadar Detectors, IEEETrans.,vol.AES-7,pp.706-709, July,1971. 73.Carpentier, M.H.:..Radars: NewConcepts," Gordon andBreach,NewYork,1968,sec.4.6. 
 For < small, sin 5  may be replaced by (ha + h,)/R so  that'^ = 2ha(ha + h,)/R s 211. h,/R. The latter expression  Figure 12.1 Propagation over a plane reflecting surface. 
 W. B. Adams, “Phased array radar performance with wideband signals,” AES Conv. 
 Onewayto establish some absolute basis isto give the ~bserved value ofthe ratio ofminimum detectable signal power to average noise power, forone particular system. This isdone inTable 22, inwhich aredisplayed therelevant constants ofthesystem selected. TABLE 22.-(2HARACTERISTICS OFASAMPLE SYSTEM Type ofindication. 
 Stretch Pulse Compression.57–60,62 Stretch pulse compression is a technique for  performing LFM pulse compression of wideband waveforms using a signal processor  with bandwidth that is much smaller than the waveform bandwidth, without loss of  signal-to-noise ratio or range resolution. Stretch pulse compression is used for a single  target or for multiple targets that are located within a relatively small range window  centered at a selected range.  Figure 8.28 shows a block diagram of a stretch pulse compression system. 
 Figure 4.15. Schematic block diagram of ASV Mk. VIB [ 6].Airborne Maritime Surveillance Radar, Volume 1 4-15. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars.  SPACE-BASED REMOTE SENSING RADARS  18.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 representing the data, and several alternative methods for data analysis. 
 H. Ackroyd: Uniform Complex Codes with Low Autocorrelation Sidelobes, IEEE Trans., vol. IT-20, pp. 
 In the adaptive MTI implementation described above, the number of zeros allo - cated to each of the two cancelers was fixed, based on an a priori assessment of the  clutter suppression requirement. The only variation possible would be to completely  bypass one (or both) of the MTI cancelers if no land clutter or weather or chaff returns  are received on a given radial. A more capable system can be implemented if the num - ber of zeros can be allocated dynamically to either clutter source as a function of range. 
 POLARIZED ON RECEIVE &IGURE   4HIS ARCHITECTURE REQUIRES LESS MASS AND OFFERS GREATER EFFICIENCY THAN ALTERNATIVES  WHILE CAPTURING ALL OF THE POTENTIAL INFORMA 
  PRODUCES A MUCH SHARPER SLOPE AT THE HORIZON THAN A SHAPED REFLECTOR OF EQUAL  HEIGHT 4HE ARRAY FEED ENABLES SUPERPOSI 
 The majority of radars that operate  ovnr the sea usually employ horizontal polarization. Air-surveillance radars with horizontal  polarization achieve greater range than with vertical polarization because of the higher  reflection coefficient of horizontal polarization (Sec. 12.2). 
 Villasenor, “Decorrelation in interferometric radar echoes,” IEEE Trans  Geoscience and Remote Sensing , vol. 30, pp. 950–959, 1992. 
 Conv. Rec.,  (supplement to IEEE Trans.  vol. 
 Target detection is similar to that of monostatic radar: target illuminated by the transmitter and target echoes detected and processed by the receiver. Tar- get location is similar to but more complicated than that of a monostatic radar: total signal propagation time, orthogonal angle measurements by the receiver, and some estimate of the transmitter location are required to solve the transmitter-target-receiver triangle, called the bistatic triangle. Continuous-wave (CW) waveforms can often be used by a bistatic radar because site separation, possibly augmented by sidelobe cancellation, provides sufficient spatial isolation of the direct-path transmit signal. 
 LIKE TECHNOLOGY AND WAS ORIGINALLY BASED ON THE MILITARY )&& )DENTIFICATION &RIEND OR &OE  SYSTEM /THER !PPLICATIONS  ! HIGHLY SIGNIFICANT APPLICATION OF RADAR THAT PROVIDED  INFORMATION NOT AVAILABLE BY ANY OTHER METHOD  WAS THE EXPLORATION OF THE SURFACE OF THE PLANET 6ENUS BY AN IMAGING RADAR THAT COULD SEE UNDER THE EVER 
 A range compressed signal RCS1 with time delay 0.5 μs. Figure 6. Three range compressed signals RCS1, RCS2, RCS3 and their sum RCS. 
 BASED 3!2 PRECEDENTS . 
   PP n   $ECEMBER   $ ( #OOPER  h"INARY QUANTIZATION OF SIGNAL AMPLITUDES EFFECT FOR RADAR ANGULAR ACCURACY v  )%%%  4RANS  VOL !NE 
 It  might consist of an air-core inductance with taps along its length to which are attached  n ,f capacitance to ground. A transformer is used to match the impedance of the delay line to that  of the load. A perfect match is not always possible because of the nonlinear impedance  characteristic of microwave tubes. 
 END NOISE TO MIXER NOISE  D"  D"  D" 3ACRIFICE IN MIXER DYNAMIC RANGE  D"  D"  D" $EGRADATION OF SYSTEM NOISE TEMPERATURE DUE  TO MIXER NOISE D"   D"   D" 4HE SAME CONSIDERATIONS APPLY TO THE SETTING OF THE NOISE LEVEL AT THE INPUT TO THE  !$ CONVERTERS 4RADITIONALLY  THE NOISE CONTRIBUTION OF THE !$ CONVERTER WAS CON 
 For very high powers, the rising-sun system has considerable promise. Unlike strapped systems, the rising-sun system permits the anode tobemade with acircumference and alength which arenot small compared toawavelength without producing mode instabilities. Thus even athigh frequencies large cathodes and large emissions arepossible. 
 But when the air is crowded with civilian traffic the same  difficulties may be experienced, and the advantage of  coded beacons is obvious.  Beacons can provide an indication of bearing with a  remarkable accuracy, but for air-travel we must know  ;  . 162 HOW RADAR WORKS  more than bearing; we must have some radar device to  indicate height. 
 However. the smaller effective antenna aperture associated with the broad receiving  beam results in less echo signal. This must be compensated by greater transmitter power. 
 -ULTISENSOR 4RACKING !PPLICATIONS AND !DVANCES  VOL )))  9 "AR 
 OE-9, pp. 291–308, 1984. 12. 
 BAND OF FREQUENCIES )T CAN RADIATE A HIGHER MEAN POWER LEVEL PER SPECTRAL LINE THAN THE TIME 
 TION AND TRANSPARENT TO ORTHOGONAL POLARIZATION )T IS ORIENTED TO BE TRANSPARENT TO THE 8 
 M. Bracalente, D. H. 
 Today the  possibilities are simple to list after many disappointments due to disillusionment:   Optimization of the shape and style (wideband)   Covering with Radar absorbing material (wideband)   Layering of the outer -surface materials (narrowband)   These three possibilities will be further discussed in the coming sections.   11.8.1  Optimization of Shape and Style   It was shown by the representation of backscattering characteristics of simple bodies that, based upon the projection surface , the sphere had the smallest scattering cross -section, with:   € σKugel=r2π  (11.24)  For bodies with differing curvature in both planes the following applies, where r1 and r2 are the  two radii of curvature:   € σ=r1r2π (11.25)   From this it follows that the radius of curvature is to be minimized.  In these cases, in which  not all aspect angles are expected, one can also consider working with mirrored reflection at  diagonal angles of incidence, as Figure 11.18 shows. 
 Cook: Effects or Limiting on the Detectability of Partially Time Coincident  Pulse Compression Signals, IEEE Trans., vol. MIL-9, pp. 17-24, January, 1965. 
 The term Bragg scatter is often used to describe the mechanism for the small-perturbation model. The idea comes from the concept illustrated in Fig. 12.66. 
 "ASED -IDCOURSE $EFENSE SYSTEM  INCLUDING SEARCH  ACQUISITION  TRACKING  DISCRIMINATION  AND KILL ASSESSMENT 309 
 The parametric amplifierl0.I8 has  the lowest noise figure of those devices described here, especially at the higher microwave  frequencies. Ifowever, it is generally more complex and expensive compared to the other  fro11 t-ends.  'The transistor a~rlplifier can be applied over most of the entire range of frequencies of inter-  est to radar.10-'9.20 The silicon bipolar-transistor has been used at the lower radar frequencies  (bclow I, batld) atld tile galiu~tl arserlide field-eKect transistor (GaAs FET) is preferred at the  I I I I I I Ill I I  5000 10,000 30,000  Frequency - MHz  Figure 9.4 Noise figures of typical microwave receiver front-ends as a function of frequency- 6 0  50  m = 4 0.-  I  ?!  1T'  w 30.-  0 z  2 0  10- -  Image-recovery mlxer wtlh  r  parametric amplifier  RECEIVERS, DISPLAYS, ANDDUPLEXERS 351 Thenoisefigureofareceiver withnoisefigureFr,preceded byRFlossesequaltoLRFis F2-1F0=FI+------=LRF+(Fr-l)LRF=FrLRFG1 whereF1=4F,G1=I/LRF,andF2=Fr· 9.4LOW-NOISE FRONT-ENDS(9.15) Earlymicrowave superheterodyne receivers didnotuseanRFamplifier asthefirststage,or front-end. 
 Kimpel, D. S. Zrnic, S. 
 The purpose of the rear receiver is to provide a coherent reference for detec- tion of the front (target) signal. The rear signal, after conversion to IF, closes the automatic frequency control (AFC) loop around the microwave local oscillator (LO) and acts as the reference for the IF coherent detector. The target signal, received in the front antenna, is heterodyned to IF and amplified in a relatively wideband amplifier (typically 1 MHz or wider). 
 For example, a typical waveform in this class  has N contiguous pulses of width τ whose spectra of width 1/ t  are placed side by side  in frequency to eliminate gaps in the composite spectrum. Since the waveform band - width is now N/t , the nominal compressed-pulse width is t /N. These relationships are  summarized in Table 8.7. 
 Astropical (butnotequatorial) climates arenotedfortheirfineweather, itisnotsurprising to findthemostintenseducting occurring 'insuchregions.32Intemperate climates ducting is morecommon insummer thaninwinter.Itdoesnotoccurwhentheatmosphere iswellmixed, acondition generally accompanying'poor weather. Whenitiscold,rough,stormy, rainy,or cloudy,theloweratmosphere isweillS'tirred~upandpropagation islikelytobenormal. Both roughterrainandhighwindstendto'increase atmospheric mixi,ng,consequently reducing the occurrence ofducting. 
 One limiting factor of superresolution techniques is that they often require the  received signals to obey accurate models of the array manifold. This can be violated  due to propagation effects (e.g., spatial spreading and nonstationarity) as well as instru - mental effects (e.g., channel mismatch). These factors also affect the performance of  adaptive antennas for jammer cancellation, but model mismatches can degrade the  performance of superresolution techniques more severely. 
 These lower level functional suites are connected by standardized bus - ses, which may be fiber optic or wired. The programmable devices are controlled by  software operating environments invoking programs. The architecture objective is to  have standard interfaces, few unique assemblies, and single-level maintenance. 
 46. J. L. 
 IN GROUND 
 The middle threshold divides the “tentative” region into a tentatively correlated region  and a tentatively uncorrelated region. The rationale in setting the threshold is to set the  two associated error probabilities equal for a particular separation. The threshold TM  was found by using simulation techniques and is also shown in Figure 7.42. 
 13ofthisseries. z‘~he changes ofintensitv caused bystatistical fluctuations ofthemmber Of raindrops within apulse packet aresmall compared with these changes.. 84 PROPERTIES OF RADAR TARGETS [SEC. 
 COUNTERMEASURES %##-  TO ENSURE EFFECTIVE USE OF THE %- SPECTRUM DESPITE AN ENEMYS USE OF %7 ACTIONS 4HIS CHAPTER IS DEVOTED TO THE DESCRIPTION OF THE %##- TECHNIQUES AND DESIGN PRIN 
 The output power capability of GaAs FETs increases almost linearly with increases in the total gate width, while the power gain decreases slowly with increasing total gate width. The maximum practical total gate width that can be accommodated on a single chip is limited by the following factors: 1. Yield of the device: A typical dc processing yield may be 0.995 per 100 |xm of gate periphery. 
 PLER PREDICTED BY THE AUTOMATIC TRACKER WITH ACCURACIES RPR  RPP  RPI  RP$  4HE PRE 
 TO 
  
 Hansen, “High range resolution radar measurements of the  speed distribution of breaking events in wind generated waves: Surface impulse and wave energy  dissipation rates,” J. Phys. Oceanog ., vol. 
 " ANTENNA v  )NTL  *OUR 2EM 3ENS  VOL   PP n    - 3HIMADA  h,ONG 
 RANGE DOMAIN 4HE FREQUENCY 
 40. J. P. 
 Materials  such as polyethylene, polystyrene, Plexiglas, and Teflon are suitable for small microwave  lenses. They have low loss and may be easily shaped to the desired contour. Since the velocity  of propagation is greater in air than in the dielectric medium, a converging lens is thicker in the  middle than at the outer edges, just as in the optical case. 
 Shore stations  and ships also have the ability to specifically interrogate shipborne AIS transponders  to initiate the sending of particular data. AIS has three major uses: to enhance the  bridge team’s situational awareness, to aid VTS activities, and to provide data to assist  national security. The intention of IMO is that ships will normally display AIS data on  the radar screen as it complements radar-derived data, adding to the integrity of the  presence, position, and velocity of targets and also giving increased target information. 
 STATIC RADARS  FOR EXAMPLE  THE RANGE EQUATION  TARGET DOPPLER  TARGET RADAR CROSS SECTION  AND SURFACE CLUTTER 4HUS  THE REMAINDER OF THIS CHAPTER WILL CONCENTRATE ON THE BISTATIC RADAR TOPIC  DEVELOPING MULTISTATIC EXCURSIONS AND DEVIATIONS ONLY WHEN NECESSARY 0ASSIVE RECEIVING SYSTEMS  OR  ELECTRONIC SUPPORT MEASURE  %3-  SYSTEMS  OFTEN  USE TWO OR MORE RECEIVING SITES 4HEIR PURPOSE IS TYPICALLY TO DETECT  IDENTIFY  AND LOCATE TRANSMITTERS SUCH AS THOSE FROM MONOSTATIC RADARS 4HEY ARE ALSO CALLED  EMITTER  LOCATORS 4ARGET LOCATION IS BY MEANS OF COMBINED ANGLE MEASUREMENTS FROM EACH SITE EG  TRIANGULATION  OR TIME 
 COUPLING MUST EXACTLY CANCEL THE COUPLING FROM ALL OTHER ELEMENTS 4HEY HAVE USED THIS TECHNIQUE TO PROVIDE A GOOD MATCH ON AN ULTRALOW 
 GATE CAPACITOR CHARGES TO A VOLTAGE PROPORTIONAL TO THE AREA OF THE FIRST HALF OF THE TARGET VIDEO PULSE  AND THE LATE 
 SCAN   " 
 DISTRIBUTIONS 4HE LATTER WAS INTRODUCED TO CHARACTERIZE THE PARTICULAR BEHAVIOR OF LOW 
 As with the CW  situation, the greatest loss occurs at the maximum scan angle, which is assumed to be  60°. For this situation, the criterion chosen is to allow a spectrum that loses 0.8 dB of  energy on target due to frequency-scanned spectral components. For a beam scanned  to 60 °, this becomes  Bandwidth (%) = 2 beamwidth ( °) (pulse)  Note that this is twice the bandwidth permitted for the CW situation. 
 Sever a1methods of folding delay lines have been suc- cessfully used, one ofwhich is shown inFig. 16.33. Inaddition totheintersecting truss members, there canbeseen sixvertical tubes. 
 In an alternative configuration,  the feed network could be designed for a constant amplitude aperture distribution to  give highest transmit power on the target, and the receiver gain control could be used  to provide an amplitude taper for the sum channel. Perhaps a secondary feed system  could be added for the difference channels. Poirier97 has analyzed this case, the effect  on noise, and the degradation due to amplitude quantization steps. 
 TO 
 SomeCFAscanbeturned onandoffbythestartandstopoftheRFpulse,thusrequiring nomodulator at.all.Triodeand tetrodegrid-controlled tubesmaybemodulated byapplying alow-power pulsetothegrid. Platemodulation isalsousedwhentheradarapplication cannottoleratetheinterpulse noise thatresultsfromthosefewelectrons thatescapethecutoff action ofthegrid. Thebasicelements ofonetypeofradarmodulator areshowninFig.6.13.Energyfroman external sourceisaccumulated intheenergy-storage elementataslowrateduringtheinter­ pulseperiod.Thecharging impedence limitstherateatwhichenergycanbedelivered tothe storageelement. 
 The off-nadir angle of PALSAR (Phased Array type L-band Synthetic Aperture Radar) in this table is 21.5 degrees. ISR: Incoherent Scatter Radar. Data Group InstrumentCenter LatitudeCenter LongitudeCenter Observation Time (UTC:Y/M/D HH/MM)Piercing LatitudePiercing Lontitude 1PALSAR 65.193 −148.439 2011/03/19 07/32 64.786 −151.022 Poker Flat ISR65.130 −147.471 2011/03/19 07/30 64.650 −148.000 2PALSAR 65.194 −147.369 2011/03/31 07/28 64.782 −149.949 Poker Flat ISR65.130 −147.471 2011/03/31 07/28 65.130 −147.471 3PALSAR 65.183 −147.450 2010/08/06 21/06 64.800 −144.832 Poker Flat ISR65.130 −147.471 2010/08/06 21/08 65.370 −145.070 3.2. 
 J. P. Campbell, “Back-scattering characteristics of land and sea at X band,” in Proc. 
 DEPENDENT  IS EXECUTED BY SEQUENTIAL SELECTION OF THE APPROPRIATE FEEDS 4HE FEED HORNS ARE ( 
 Barton in “Modern Radar,” R. S. Berkowitz (ed.), New York: John Wiley & Sons, 1965, chap. 
 Shaping  is the selection or design of surface profiles so that  little or no energy is reflected back toward the radar. Because target contours are dif - ficult to change once the target has become a production item, shaping is best imple - mented in the concept definition stage before production decisions have been made.  Radar-absorbing materials actually soak up radar energy, also reducing the energy  reflected back to the radar. 
 The cross section thus defined exceeds the average cross section byanamount asyetunlmo~vn. The values forcross sections inTable 3-2hare been obtained using this definition ofcross section.. SEC, 3.9] ACTUAL COMPLEX TARGETS 79 Amore serious modification ofthedefinition ofcross section ismade necessary bythereflection ofradar waves w-hen thetarget isobserved at anelevation angle smaller than half the beamwidth and over a-water surface. 
 SCAN RATIO WAS A HIGHLY SIGNIFICANT INCREASE DUE TO FREQUENCY DIVERSITY  )NCREASED 4ARGET $ETECTABILITY  4HE RADAR CROSS SECTION OF A COMPLEX TARGET SUCH  AS AN AIRCRAFT CAN VARY GREATLY WITH A CHANGE IN FREQUENCY !T SOME FREQUENCIES  THE RADAR CROSS SECTION WILL BE SMALL AND AT OTHERS IT WILL BE LARGE )F A RADAR OPERATES AT A SINGLE FREQUENCY  IT MIGHT RESULT IN A SMALL TARGET ECHO AND  THEREFORE  A MISSED DETEC 
 WEIGHTED BY A SINE FUNCTION    O    TO SUPPRESS SIDELOBES BY  ^ D" FROM THE SURFACE  RETURN THAT OTHERWISE WOULD MASK THE DESIRED RETURNS FROM DEPTH 4HE IN SITU RESOLUTION IS NOMINALLY  ^ M WITHIN A MEDIUM OF PERMITTIVITY  ^ 4HE RADAR DYNAMIC RANGE IS  ^ D" TO PERMIT OBSERVATION OF SUBSURFACE PROFILES TO A DEPTH OF SEVERAL KM 4HE ANTENNA IS COMPRISED OF TWO SETS OF DIPOLES   M TIP 
 CHANNEL SIDELOBE BLANKER USING POSTDETECTION 34# OR 2#3 THRESHOLDING TO REMOVE SIDELOBE DISCRETES%$! +&+) 
 13. The postponed discussion ofradar functions, and ofthechoice ofim~or- tant ~adar properties tofitthese functions, isfound ofindicator types. TYPES OFRADAR INDICATORS BYL.J.HAWORTHafter this catalogue 62. 
 15 20.  5. Ridenour. 
 SCR-270 andSCR-271.—The early efforts ofthe U.S. Army Signal Corps todesign service radar equipment were inthedirection ofproduc- Fro,6.18.—SCR.27OD. ing anequipment for antiaircraft fire control and searchlight control (SCR-268; seeSec. 
 The disadvantage of using feedforward for velocity response shaping is that an additional delay must be pro- vided for each zero used to shape the response. Also, an inherent loss in improve- ment factor capability is caused by using zeros to shape the velocity response. This may or may not be significant, depending on the clutter spectral spread and the num- ber of zeros available for cancellation. 
 QUENCY CONVERSION OF SIGNALS AT THE )& FREQUENCY TO A COMPLEX REPRESENTATION   )   J1  CENTERED AT ZERO FREQUENCY  4HE BASEBAND IN 
 LENGTH  K  WHERE R AND K ARE IN THE SAME UNITS IS   ,0 0RT RFS ¤ ¦¥³ µ´ § ©¨¶ ¸·     LOG LOG O K   &REE 
 % OBSCU 
 13–39, 52–54. 75. R. 
 82. Dillard, G. M.: Mean-Level Detection Utilizing a Digital First-Order Recursive Filter, IEEE Trans.,  vol. 
 IEEE, vol. 73, pp. 301-311, February 1985. 
 A disadvantage of this detector is that it is susceptible to  interference; that is, one large sample from interference can cause a detection. This  problem can be minimized by using soft limiting. The detection performance discussed previously is based on the assumption that the  target is centered in the moving window. 
 19. M. T. 
 We analyze this type of phase error in this section. The SNR loss of the imaging result is deﬁned as Sloss. According to the geometric model in Figure 7, we apply the numerical analysis method to obtain the h–Slosscurve of the imaging result P 0. 
 ETER AT .!3!.34, v )%%% 4RANS  VOL '% 
 Thus the only problem left istoreduce therms fluctuation tothesame value everywhere. There aretwo ways ofdoing this, thefirst depending onthenature oftheamplitude fluctuations oftheclutter, thesecond on thenature ofthephase fluctuations. Aswehave seen, the rms fluctuation inamplitude isproportional tothe rms clutter amplitude. 
 SPECULAR REGION   INTERMEDIATE ANGLES FROM  TO ABOUT  THE  PLATEAU REGION   AND  NEAR 
 10.17). Itwould appear useful toexpress the r-floading interms ofthe resistance and reactance presented tothe magnetron atthe output loop. Since these quantities are difficult todetermine experimentally, the Rieke diagram isacompromise between these quantities and others which can be obtained with ease experimentally. 
 TO 
 We define a system noise temperature Ts, in which case  the available noise power is No=kToBn 231.38 10Bk−=× No=kTsBn TIME OR FREQUENCYNOISE  POWER. 29Signal-to-Noise Ratio (SNR)  • Considering the presence of noise, the important parameter for detection is  the signal-to-noise ratio (SNR) • Factors have been added for processing gain Gpand loss L • Most radars are designed so that  • At this point we will cons ider only two noise sources: 1. background noise co llected by the antenna (TA) 2. 
 K.: "Radar Systems Analysis," Prentice-Hall, Englewood Cliffs, NJ., 1964. 6. Schlerer, D. 
 AP-16,   pp. 89–97, January 1968.  6. 
 TION PROCESS 3IGNAL PROCESSING INCLUDES THE  MATCHED FILTER THAT MAXIMIZES THE OUT 
 It  should be noted that a tropospheric waveguide is not a waveguide in the true sense of the  word because there are no rigid walls that prevent the escape of energy from the guide. The refractivity gradients and their associated refractive conditions are summa - rized in Table 26.1. Atmospheric Ducts. 
 DELAY AXIS IS DETERMINED BY THE ALTIMETERS HEIGHT )F THE SEA SURFACE IS MODULATED BY WAVES  THE ALTIMETRIC DEPTH OF THE SURFACE INCREASES  WHICH REDUCES THE SLOPE OF THE WAVEFORMS LEADING EDGE (ENCE  37( IS PROPORTIONAL TO THE WAVEFORM RISE TIME )F THE SEA SURFACE IS DISTURBED BY THE WIND  THE RESULTING FINE 
 -ODE 3YNTHETIC !PERTURE 2ADAR ! 3IGNAL 0ROCESSING !PPROACH   "OSTON +LUWER !CADEMIC  0UBLISHERS    2 "AMLER  h/PTIMUM LOOK WEIGHTING FOR BURST 
 Anumberofdifferent cathode-ray-tube screensareusedinradarapplications. Theydifferprimarily intheirdecaytimesandpersistence. Theproperties ofsomeofthe ohosphors whichhavebeenusedinradarCRTsarelistedinTable9.1.Thedegreeofimage. 
 Assume initially that the two forward and two backward beams are symmetrically disposed  about {lie axis of the aircraft. If the aircraft's velocity is not in the same direction as the aircraft  Ileading. the doppler frequency in the two forward beams will not be the same. 
 Knittel, Norwood, MA: Artech House, 1972, pp. 243–253. 80. 
 LAW DETECTION -OVING 
 LOOP CONTROL SYSTEM SUCH AS 4!##!2  DESCRIBED BELOW !N EXAMPLE OF A RECEIVED CLUTTER SPECTRUM GIVEN AN ANTENNA RESPONSE IS SHOWN  IN &IGURE  A 4HE 4!##!2 FREQUENCY OFFSET THEN SHIFTS MAIN 
 10. Lewis, B. L., J. 
 3. Discussion 3.1. B-SAR—Blind SAR Data-Focusing Algorithm The focusing algorithm acts as a simple SVD decomposition. 
 29•3° Changes in the target aspect with respect to the radar can cause the  apparent center of radar reflections to wander from one point to another. (The apparent centa  of radar reflection is the direction of the antenna when the error signal is zero.) In general, the  apparent center of reflection might not correspond to the target center. In fact, it need not he  confined to the physical extent of the target and may be off the target a significant fraction of  the time. 
  
 Physical Theory of Diffraction . The singularities in GTD are overcome in the  physical theory of diffraction  (PTD) formulated by P. Ia. 
     WHERE Z  IS THE DISTANCE FROM THE FOCAL PLANE   F IS THE FOCAL LENGTH OF THE CYLINDRICAL  REFLECTOR  AND  Y IS THE HORIZONTAL DIMENSION &OR THE PARABOLIC CYLINDER  THE SURFACE DOES  NOT VARY WITH X  THE HEIGHT 4HE FEED IS GENERALLY ON THE FOCAL LINE  AND IN MANY WAYS   THE DESIGN OF PARABOLIC CYLINDER REFLECTORS IS SIMILAR TO THAT OF PARABOLOIDAL REFLECTORS  /NE SIGNIFICANT DIFFERENCE IS THAT THE FEED ENERGY DIVERGES CYLINDRICALLY RATHER THAN  SPHERICALLY  AND SO THE FEED POWER DENSITY FALLS OFF AS Q  RATHER THAN Q  4HE HEIGHT OF THE PARABOLIC CYLINDER &IGURE A  MUST ALLOW FOR BEAMWIDTH   SHAPING  AND STEERING OF THE LINEAR FEED ARRAY 7HEN THE LINE SOURCE STEERS AT ANGLE  P  FROM BROADSIDE  THE PRIMARY BEAM FROM THE SOURCE LIES ON A CONIC  AND THE INTERCEPTS AT THE UPPER RIGHT AND LEFT CORNERS OF THE REFLECTOR ARE FARTHER UP THAN IN THE CENTER  AS SHOWN IN &IGURE B 4HEREFORE  THE CORNERS OF PARABOLIC CYLINDER REFLECTORS ARE SELDOM ROUNDED IN PRACTICE 3HAPED 2EFLECTORS  &AN BEAMS WITH A SPECIFIED SHAPE ARE REQUIRED FOR A VARIETY OF  REASONS ! COMMON ELEVATION SHAPED BEAM REQUIREMENT IS TO PROVIDE EQUAL ECHO SIGNAL POWER ON TARGETS AT CONSTANT ALTITUDE )F THE TRANSMIT AND RECEIVE BEAMS ARE IDENTICAL  AND IF SECONDARY EFFECTS ARE IGNORED  THIS CAN BE ACHIEVED WITH A POWER RADIATION PAT 
 OUT SPECTRUM  SOMETHING NOT AS PRACTICAL TO DO WITH OTHER TYPES OF MICROWAVE TUBES #OAXITRON 4HE PERFORMANCE OF CONVENTIONAL GRID 
 FIGURE 14.14  Summary of RCS levels of targets discussed  in this section. The locations of targets on the chart are general  indications only. ch14.indd   16 12/17/07   2:46:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 2AYLEIGH  IT WILL PROBABLY BE VERY 2AYLEIGH 
 The develop- ment and consistent fabrication of devices as hard as this are relatively uncertain. Tradeoffs. Obviously many tradeoffs can be made during the design of each type of SBR, depending upon the mission. 
 21-23. 1975. Arlington, VA. 
 (ILL "OOK   #OMPANY    $ + "ARTON  2ADAR 3YSTEMS !NALYSIS  .ORWOOD  -! !RTECH (OUSE    ! 3 ,OCKE  'UIDANCE  0RINCTON  .* $ 6AN .OSTRAND #OMPANY    #HAP   $ # #ROSS  h,OW JITTER HIGH PERFORMANCE ELECTRONIC RANGE TRACKER v IN  )%%% )NT 2ADAR #ONF  2EC    PP n  $ , -ALONE  h&,9#!4#(%2 v  .AT $EF  PP n  *ANUARY   (OLLANDSE 3IGNAALAPPARATEN "6 ADVERTISEMENT  $EF %LECTRON  VOL   P   !PRIL  %DITOR  h)NSIDE THE %XOCET &LIGHT OF A SEA SKIMMER v  $EF  %LECTRON  VOL   PP n    !UGUST    %DITOR  h3PECIAL SERIES )SRAELI !VIONICS 
 The greater the desired radar  range, the more stringent will be the need for reducing the noise modulation accompanying the  transmitter signal. If complete elimination of the direct leakage signal at the receiver could be  achieved, it might not entirely solve the isolation problem since echoes from nearby fixed  targets (clutter) can also contain the noise components of the transmitted ~ignal.~.~'  It will be recalled (Sec. 1.3) that the receiver of a pulsed radar is isolated and protected  from the damaging effects of the transmitted pulse by the duplexer, which short-circuits the  receiver input during the transmission period. 
 A good example  of this is provided in a SAR image of the Washington Monument, courtesy of the  Environmental Research Institute of Michigan, now General Dynamics, Ypsilanti, MI.  The top illustration in Figure 17.8 illustrates the collection geometry (and the sche - matic result) of optical imagery of the Washington Monument with the Monument’s  shadow pointed toward the observer. We assume that the sun is to the south of the  Monument and the observer is to the north. 
 2.Barton. D.K...RadarSystems Analysis," Prentice-Hall, Inc.,NewJersey,1964. 3.James,H.M.,N.B.Nichols, andR.S.Phillips: ..TheoryofServomechanisms," MITRadiation Laboratory Series,vol.25,McGraw-Hili BookCompany, NewYork,1947. 
 ING  AND THRESHOLDING LOSSES    2'(02& 3ELECTION !LGORITHMS  &IRST  AS IN THE -02& CASE  ALL 02&S SHOULD BE  CLEAR AT THE MAXIMUM DESIGN RANGE 3ECOND  ALL 02&S SHOULD BE CLEAR TO THE MAXIMUM DOPPLER OF INTEREST /NE POSSIBLE SELECTION CRITERIA IS GIVEN IN %Q  !LTHOUGH THE DETAILS ARE QUITE DIFFERENT  THE BASIC PHILOSOPHY IN 02& SELECTION IS TO OPTIMIZE LONG 
 PIXEL FLUCTUATION SPECKLE  THAN COR 
 Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 16.2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Here, s 0 has been used to denote the average value of si /∆ Ai. In this formulation,  we may pass in the limit from the finite sum to the integral given by  PPGA d A Rrt t r= ∫1 420 4( )πσ Illuminated area (16.1) This integral is not really correct, for there is a minimum size for real, independent  scattering centers. 
 2139-2148. Dcccmber. 1963. 
 12.14 Range resolution applied to scatterometry. (a) Improving one dimension of a circular-beam illumination pattern, (b) Use with a fan beam.CIRCULAR BEAM (a)FAN BEAM (b) . where <f>0 = beamwidth <j)0 = transverse angle with respect to antenna axis With the further assumption that a° is essentially constant and that the difference in range across a resolution element is negligible, the expression for a° becomes 0 _ Pr(4iT)3/?3 sin 6 pt X2G0(|)o rR where rR is the short-range resolution. 
 D. Crum and R. L. 
 Arlington, Va., Apr. 21 --23, 1975.  11!1!f! Publication 75 CHO 938-1 AES. 
 For24dBcancellation, theellipticity ratiomustbe0.94.Cancellations in excessof30dBhavebeenachieved inlightrainandindry~snow.79 However, cancellations of onIyISdBorlessareobtained fromnonspherical precipitation suchasheavyrain,fromthe melting layer.andfromlargewetsnowflakes.79.80.82 Insomeheavyrainsandthunderstorms. thecancellation mightbeonly5dBB2 IthasbeenfoundthaIbettercancellation ofprecipitation isobtained whenthepolariza­ tionisnotquitecircular. Thatis.thereisaparticular elliptical polarization whichproduces the hestcancellation. 
 165. J. van Zyl and Y . 
 The ambiguity diagram for a single rectangular pulse of sine wave is  shown in Fig. 11.9. Contours for constant values of doppler frequency shift (velocity) are  shown in Fig. 
 Acoustic noise can originate  from cooling fans, and vibrations can come from shipboard or airborne radar plat - forms. Components such as klystrons and solid-state modules can have unexpected  susceptibility to vibration. RF connectors must be secure. 
 A clutter map uses adaptive thresholding where the threshold  is calculated from the return in the test cell on previous scans rather than from the sur - rounding reference cells on the same scan. This technique has the advantage in that  for essentially stationary environments (e.g., land-based radar against ground clutter),  the radar has interclutter visibility—it can see between large clutter returns. Lincoln  Laboratory33 in its moving-target detector (MTD) used a clutter map for the zero-dop - pler filter very effectively. 
 The disadvantage is that the RD algorithm can only be used on low resolution SAR images when the spatial resolution is of the order of meters. The RD reformation algorithm is used when the SAR image is StripMap data. In this paper, the inverse range Doppler (IRD) algorithm is applied via a two-dimensional fast Fourier transform (FFT). 
 and from large wet  snowflake^.^^^^^.^^ In some heavy rains and thunderstorms,  the carlcellation might be only 5  It has beer1 fourld that better cancellation of precipitation is obtained when the polariza-  tion is not quite circular. That is, there is a particular elliptical polarization which produces the  best cancellation. The optirrium elliptical polarization depends on the nature of the rain. 
 or 1 - &.  A different glint model, based on the assumption that the angular motion of a complex  target can be described by a gaussian random yaw motion of zero mean, yields the result that  the reductior~ in angle error due to frequency agility asymptotically approaches a value of 3.1  with increasing agility bandwidth.38 The model also gives the variance of the inherent glint tor  a frequency-agile radar as  var = 0.142~6 (5.5)  where )-, is the lateral radius of gyration of the collection of scatterers comprising the target.  The value of yo for a " typical" twin-jet aircraft in level flight at near head-on or near tail-on  aspect is saidJ8 to be equal to half the separation of the jet engines. 
 1958.  36. Capelli, M.: Radio Altimeter, IRE Trans., vol. 
   PP n    ( -C.AIRN ET AL  h)DENTIFICATION OF AGRICULTURAL TILLAGE PRACTICES FROM # 
 56.Reed.R.H.:Modified MagicTeePhaseShifter,IRETrans.,no.PGAP-I, pp.126-134. February, 1952. 57.Barrett. 
 R. K. Moore, Y. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 19.42  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 23. 
   '2/5.$ %#(/  £È°x  * 6 %VANS AND ' ( 0ETTENGILL   h4HE SCATTERING BEHAVIOR  OF THE MOON AT WAVELENGTHS OF      AND  CENTIMETERS v * 'EOPHYS 2ES  VOL   PP n    * 7 7RIGHT  h! NEW MODEL FOR SEA CLUTTER v  )%%% 4RANS  VOL !0 
 DUCED BY PROPAGATING THE STATE IN POLAR COORDINATES 4HE #ARTESIAN%ARTH 
 WATT RANGE WITH MAIN 
 A. Gebhard, “Evolution of naval radio-electronics and contributions of the Naval Research  Laboratory,” Naval Res. Lab. 
 Bernard and D. Vidal-Madjar, “C-band radar cross-section of the Guyana rain forest: possible  use as a reference target for spaceborne radars,” Remote Sensing of Envir ., vol. 27, pp. 
 Insome respects “radar cross section” isa more appropriate name foruinsofarasitindicates that weareconcerned only with thepower scattered directly back toward thetransmitter. Itisessential torealize that the cross section ofagiven target will depend notonly upon thewavelength but upon theangle from which the target isviewed bytheradar. The fluctuation ofuwith “target aspect,” asitiscalled, isdue totheinterference ofreflected waves from various parts ofthetarget (see Chap. 
  IMAGE PRODUCTS WERE FAR NOISIER THAN THOSE OF 3EASAT  WHOSE SENSITIVITY WAS n D" )N SPITE OF THAT HANDICAP  HOWEVER  * 
 Internal fluctuation ofclutter.48Although cluttertargetssuchasbuildings, watertowers,bare hills.ormountains produce echosignalsthatareconstant inbothphaseandamplitude asa function oftime,therearemanytypesofclutterthatcannotbeconsidered asabs01utely stationary. Echoesfromtrees,vegetation, sea,rain,andchafffluctuate withtime,andthese fluctuations canlimittheperformance ofMTIradar. Because ofitsvariednature,itisdifficult todescribe precisely theclutterechosignal. 
 Mumford, W. W., and E. Scheibe:" Noise: Performance Factors in Communication Systems," Hori­ zon House-Microwave, Inc., Dedham, Mass. 
 SCATTER 2#3 OF MORE COMPLEX BODIES HAS BEEN SIMULATED AND MEA 
 Aronoff and N. Greenblatt, “Medium PRF radar design and performance,” Hughes Aircraft  Report, presented at IEEE National Radar Conference 1975. 60. 
 (ALL  )NC    CHAP   * * 'OSTIN  h4HE '% SOLID 
 M., and J. J. Stephenson: A Versatile Three-Dimensional Ray Tracing Com- puter Program for Radio Waves in the Ionosphere, Office Telecom. 
 The  user (or buyer) should attempt lo limit the requirements to statements of performance rather  than give them in terms of specific radar characteristics which restrict the radar designer in the  choices availahle.  Characteristics of a long-range air-surveilla.nce radar. To illustrate the nature of a long-range  air-surveillance radar. 
 This description provides insight into the intrinsic im- pedance variation of the aperture when it is isolated from other effects, as in the case where each element has an independent feed (e.g., its own generator and isolator). In this case it is a simple matter to measure the voltage-standing-wave ratio (VSWR) in any line and determine exactly the extent of the impedance and mismatch variation. For many feed systems this is not possible, and a measure- ment of the reflected energy will provide erroneous information and a false sense of security. 
 Anelectron atpoint 1?,however, isina decelerating r-felectric field. ASaresult ofthe reduction inelectron velocity, the radius ofcurvature ofitspath isincreased. Ifthe fre- quency ofoscillation isappropriate, this electron will always beina decelerating field asitpasses before successive anode segments. 
 ARRAYS &)'52%  %XAMPLES OF THE ANTENNA PATTERNS ACHIEVED IN SEVERAL CASES 
  3YNCHRONIZER  
 A balanced mixer suppresses the even harmonics of  the LO signal. A do11hle-/,ala11cecl mixer is basically two single-ended mixers connected in  parallel and 180" out of phase. It suppresses even harmonics of both the RF and the LO  signals.8·55  Reactive image termination. 
 If a radar is capable of good range-resolution it is also capable of good range  accuracy.  ('lrtrrer retirccrior~. A short pulse increases the target-to-clutter ratio by reducing the clutter  contained within the resolution cell with which the target competes. 
 anode and thus reduce the magnetic field gap. Since the weight ofa magnet which will produce agiven magnetic field strength over agiven cross-sectional area increases very rapidly with the length ofthe gap, considerable magnet weight canbesaved inthis manner. Itiscustomary tosupply this type ofmagnetron permanently attached toitsmagnet. 
 132–137, 2005. 125. A. 
 It may even  act as a communication system, directing high-gain beams toward distant receivers and  transmitters. Complete flexibility is possible; search and track rates may be adjusted  to best meet particular situations, all within the limitations set by the total use of time. Chapter 13 *  Portions of this chapter that appeared in earlier editions of the Radar Handbook  were written by the late  Theodore C. 
 FERE WITH THE RADARS ABILITY TO DISTINGUISH A DESIRED TARGET 4HIS BACKWARD REFLECTED ENERGY IS CALLED CLUTTER .OT ONLY IS THE MAGNITUDE OF THE REFLECTED WAVE REDUCED  BUT ALSO THE PHASE OF THE  WAVE IS ALTERED &OR HORIZONTALLY OR VERTICALLY POLARIZED WAVES AT LOW GRAZING ANGLES  THE PHASE CHANGE UPON REFLECTION IS APPROXIMATELY  7HENEVER TWO OR MORE WAVE TRAINS TRAVELING OVER DIFFERENT PATHS  INTERSECT AT A POINT IN SPACE  THEY ARE SAID  TO INTER 
 Hence, in  high attenuation soils, SAR techniques may not provide any useful improvement to  GPR systems. SAR techniques have been applied to GPR but very often in dry soils  with low attenuation. SAR techniques typically require measurements made using transmitter and  receiver pairs at a number of antenna positions to generate a synthetic aperture or to  focus the image. 
 Oppenheim and R. W. Schaefer, Discrete Time Signal Processing , Englewood Cliffs, NJ:  Prentice-Hall, 1989. 
 In the discussion above, the assumption was implicitly made that clutter returns are  stationary and distributed in range. The above definitions will be equally valid before  and after pulse compression. For a single piece of point clutter, as often used in actual  radar stability measurements, the definition of clutter attenuation would have to be  changed as follows to provide identical results: clutter attenuation (CA), point clutter:  In moving-target indication (MTI) or Doppler radar,  the ratio of the total energy in the received point clutter return at the input to the processor,  to the total energy in the point clutter residue at the output of the processor, multiplied by the  noise gain of processor. 
 (From OlillalldQlleell.30) Table2.1aRadarcrosssection(squaremeters)oftheT_3866 Head-on aspect(±1.0degree) X,.,. XI.R Svv Lvv Percentile 205080205080205080205080 Landing gearup 0.330.831.70.210.531.21.63.14.71.51.82.2 Landing gearextended 0.531.63.50.240.802.1I.l2.34.40.992.64.5 Table2.lbMedian crosssection(Xl.lJforaspectsnearnose-on Azimuth angle(degrees) Azimuth angle(degrees) Elevation Elevation angle 0 2 5 7 angle 0 2 5 7 () (Un 16 0.72 0.45 0.90 1.2 6 0.68 0.61 0.99 0.82 18. 0.43 0.44 1.3 0.84 8 1.2 0.94 1.7 2.2 20 0.43 0.52 0.63 0.64 10 1.4 1.6:u 1.4 22 0.45 0.66I.ll.l 12 U.70 1.0 1.6 2.1 24 0.65 14 0.79 0.60 0.63 1.5 Xu.:Transmit leftcircular polarization, receiveleftcircular(Xband).XLR:Transmit leftcircular polarization, receiverightcircular(Xband).Svv:Transmit verticalpolarization, receivevertical(Sband). 
 Setler, L R .. D.R. Snavely, D. 
 EAR RESPONSE 2ECEIVERS THAT INCLUDE SOME FORM OF GAIN CONTROL MUST DISTINGUISH BETWEEN INSTAN 
 QUENTLY STRETCHED TO FIVE YEARS  40 PROVIDED VALUABLE DATA FOR AN IMPRESSIVE THIRTEEN YEARS 40 WAS FORMALLY DECOMMISSIONED IN $ECEMBER  !S IS TRUE FOR MOST RADARS   THE RECEIVED WAVEFORM PRODUCED BY AN INDIVIDUAL PULSE  FROM 4/0%8 WAS CORRUPTED BY COHERENT SELF 
 TheJ0amplitude appliesmaximum response tosignalsatzerorangeinaradarthatextracts thedocdoppler-frequency component. Thisistherangeatwhichtheleakage signalandits noisecomponents (including microphony andvibration) arefound.Atgreaterranges,where thetargetisexpected, theeffectoftheJ0Besselfunction istoreducetheecho-signal amplitude incomparison withtheechoatzerorange(inaddition tothenormal rangeattenuation). Therefore, iftheJ0termwereused,itwouldenhance theleakage signalandreducethetarget signal.acondition opposite tothatdesired. 
 W. R. East: The Microwave Properties of Precipitation Parti- cles, Q. 
 It is also assumed that the IF  filter characteristic approximates the matched filter, so that the oirtput signal-to-noise ratio is  maximized.  2.3 RECEIVER NOISE  Since noise is the chief factor limiting receiver sensitivity, it is necessary to obtain some means  of describing it quantitatively. Noise is unwanted electromagnetic energy which interferes with  the ability of the receiver to detect the wanted signal. 
 12.14 .—Fast-time-oonstant circuit. ingcondenser. The latter course is much simpler and usually isthe one adopted. 
 OF 
 The amplitude and phase of the signals delivered by the N auxiliaries are controlled  by a set of suitable weights: denote the set with the N-dimensional vector W = (W1, W2,  …, WN). The jamming signal is canceled by a linear combination of the signals from the  auxiliaries and the main antenna. The problem is to find a suitable means of controlling  the weights W of the linear combination so that the maximum possible cancellation is  achieved. 
 For each sub-aperture, the absolute pixel value of pixel (i,j)is used as the RCS amplitude Rij(k)in angle θ(k). For each pixel (i,j), the pseudo-probability Pij(k)of scattering in θ(k)can be obtained by Equation (1). The aspect entropy Ha(i, j)of each pixel (i, j)can be calculated by Equation (2). 
 TIME ADAPTIVE PROCESSING 34!0  WAS ALSO DEVELOPED TO IMPROVE  -4) PERFORMANCE OF SEPARATELY MOVING TRANSMIT AND RECEIVE PLATFORMS 3INCE BISTATIC  CLUTTER EXHIBITS NONSTATIONARY SPACE 
 28 Stretch pulse compression system block diagramRF Inputf0 fIF xin(t) xIF(t) fR xR(t)Correlation MixerStretch Pulse Compression Processor OutputBandpass FilterSpectr um Analysis or Reduced-Bandwidth Pulse Compression Filter Reference Waveform Generator ch08.indd   31 12/20/07   12:50:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 
 629–635, September 1970. 31. V . 
 On the basis of this  criterion, the resultant maximum deviation from the parabolic condition (feed at  focus) would be ±l/32. Displacement of the feed along the focal axis (the z-axis in  Figure 12.1) produces an even-order phase error on the aperture illumination. This  results in modest beam broadening and some filling of the first null, but is normally  not too detrimental. 
 Andrews. G. A .. 
 receiver. The .receiver. of the simple CW radar of Fig. 
 K. Spencer, “Stochastically con - strained spatial and spatio-temporal adaptive processing for nonstationary hot-clutter cancella - tion,” in Applications of Space-time Adaptive Processing , R. K. 
 Consequently, the input and output impedances are dynamically varying, and the  input impedance changes very dramatically. The dramatically changing input imped - ance will present an undesirable load to the preceding amplifier stage supplying the  RF drive power. This may very well send the previous stage into unwanted oscil - lation. 
 IED BETWEEN  AND  RPM $ESPITE THE PERCEIVED MODERNITY OF TODAYS CHART RADARS  IT WAS CONNECTED TO AN OPTIONAL  #HART #OMPARISON 5NIT   WHICH WAS AN OPTICAL SYSTEM  ALLOWING THE RADAR IMAGE TO BE DISPLAYED IN COINCIDENCE WITH A PAPER CHART 4HE FACILITY TO ALLOW h.ORTH 
 But the man who has become conservative,  and who has hidebound ideas of radio theory, remains so  puzzled by the comparative novelty of radar technique  that he is at a great disadvantage. To him all valve  cathodes are earthed. All grids stay at some negative  potential, all anodes usually end up at ‘high-tension  positive, and the whole purpose of the circuits in which  82  . 
 These interfering signals are commonly referred to as sea clutter or sea echo. Since the sea presents a dynamic, endlessly variable face to the radar, an understanding of sea clutter will depend not only on finding suitable models to describe the surface scattering but on knowledge of the complex be- havior of the sea as well. Fortunately, a close relationship between radar and oceanography has grown up in the remote-sensing community, leading to the ac- cumulation of a large amount of useful information about scattering from the sea and how this scattering relates to oceanographic variables. 
 CISELY ON AXIS AND INCREASES WITH DISPLACEMENT FROM THE AXIS 4HE CROSS 
  R K 
 0  cu "' -s e 2.0  cu u  n. +-0 0 vi  X LO  ~  O 0.1 0.2 0.3  0 Squint angle Oq / Os  0.4 0.5 0.6  2 3 4  Beam crossover, dB 0.7  5 6 Figure 5.11 Slope of the angular-error  signal at crossover for a monopulse  and conical-scan tracking radar. 08 =  half.power beamwidth. 
 1T·4, pp. 34-38, Marchr 1958.  55. 
  
 NOISE FIGURE 4HE 2& POWER IS GENERATED BY DIRECT AMPLIFICATION THROUGH MODULAR SOLID 
 Sincetheprobability ofafalsealarmistheprobability thatnoisewill crossthethreshold, Eq.(2.24)givestheprobability ofafalsealarm,denoted Pfa. Theaveragetimeinterval between crossings ofthethreshold bynoisealoneisdefinedas thefalse-alarm timeTra, . I N 7fa=lIm-N°L1k N-+<Xl k='l where1kisthetimebetween crossings ofthethreshold VTbythenoiseenvelope, whenthe slopeofthecrossing ispositive. 
 IT-6, pp. 145-267, Apri~ 1960.  44. 
 14.Raemer, H.R.,andA.B.Reich:Correlation DevicesDetectWeakSignals,Electronics, vol.32,no.21, pp.58-60,May22,1959. 15.Lee,Y.W.:Application ofStatistical Methods toCommunication Problems, MITResearch Lab. Electronics Tech.Rept.181,Sept.I,1950. 
 But more important, a pulse radar  with ambiguous prf can result in lost targets. If the transmitter is pulsed just when the ground  echo arrives back at the radar, it will not be detected. Thus, altitude holes exist at or near those  altitudes where the echo time is an integral multiple of the pulse-repetition period. 
 The range then is found from Eq. 4.11, where  ∆f f f f f f f = − − −2 0 2 1 0 1 2 or or ( ) /  (4.14) An example is shown in Table 4.8. If more than two targets are encountered during a dwell time, ghosts again result, as  only N − 1 simultaneously detected targets can be resolved ghost-free where N is the  number of FM slopes. 
 18, many of which now employ monopulse techniques to develop off-boresight error signals. Obviously, techniques which require the antenna to be boresighted on the target are limited in simultaneous surveillance and height finding capability. Typically they make a measurement on a single target at a time and usually also require a designation at least in range and azimuth by an accom- panying search radar. 
 Two such  tra<lcwind areas that have been studied lie between Brazil and the Ascension lslands29 and  between Southern California and Hawaii.·'° The tra<lewind temperature inversion is usually  found over the eastern portions of the tropical oceans. In these regions, there is a slow-sinking  of high-altitude air (large-scale subsidence) which meets low-level maritime air flowing toward  the equator. The general sinking of air from high altitudes results in adiabatic heating due lo  compression. 
 Reasonably long life has been demonstrated with CFAs. Operation for greater than 10,000  hours is not unusual in some tubes." The good phase stability and short electrical length of  CFAs make it possible to operate tubes in parallel to achieve greater power than available  from a single tube, as well as provide redundancy in the event of a single tube failure. The CFA  behaves as a saturated amplifier rather than as a linear amplifier. 
 NOISE RATIO CAN BE IMPROVED WHEN NECESSARY BY MEANS OF MULTISWEEP OR MULTISTEP SIGNAL INTEGRATION SCHEMES 4HE PRICE PAID FOR MUCH OF THIS VERSATILITY IS THE REQUIREMENT FOR MORE ACTIVE TEST TIME P ER TARGET ROTATION  THEREBY  INCREASING MEASUREMENT COSTS )NDOOR 4EST 2ANGES  )NDOOR TEST RANGES OFFER PROTECTION FROM WEATHER AND THERE 
 A GNSS blackout, perhaps caused by intentional  or unintentional jamming, would prevent AIS from being an effective system, possibly  over a wide area and for an appreciable time. Future systems might increasingly exploit the complementary aspects of radar and  AIS. This could improve the overall target-tracking capability available to ships and  will give support for detecting cooperative targets in clutter. 
 The knife edge, or ridge, is obtained with a single pulse of sine wave. Its orientation  is along the time-delay axis for a long pulse, along the frequency axis for a short pulse, or it can  be rotated to any direction in the TR, f, plane by the application of linear frequency modula-  tion. The bed of spikes in Fig. 
 TOR AND CALIBRATE ITS PERFORMANCE !%3!S HAVE DEMONSTRATED SIMULTANEOUS MULTIPLE WEAPON DELIVERIES .   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°££ !IR 
 Because the evaporation duct is of great importance for over-water  EM propagation, it warrants a detailed discussion. This discussion appears in its own  section below. Surface-based ducts occur when the air aloft is exceptionally warm and dry com - pared with the air at the Earth’s surface. 
 5,   pp. 636–641, September 1982. 36. 
 Schneider, E. G.: Radar, Proc. IRE, vol. 
 PULSE   p  4OTAL MASS  NOT INCLUDING CONSUMABLES SUCH AS FUEL FOR PROPUL SION OR ATTITUDE CONTROL4!",%  4/0%8 0ARAMETERS 0ARAMETER 6ALUE 5NITS ,&- RATE  -(Z§S 0ULSE DURATION  §S 0ULSE "7 RADIATED   -(Z 4IME r BANDWIDTH   DIMENSIONLESS  0ULSE RESOLUTION  M #ARRIER +U BAND   '(Z #ARRIER # BAND   '(Z )& FREQUENCY  -(Z 3TRETCH BANDWIDTH  -(Z 2ANGE TIME SPAN  NS. £n°ÎÈ  2!$!2 (!.$"//+  STATISTICAL INDEPENDENCE REQUIREMENT EVALUATED FOR THE 4/0%8 INDICATES THAT THE MAXI 
 When his 80 m, the height of the target P exceeds height di ﬀerence threshold, thus the imaging result of target P on the reference plane appears severe defocusing. (a) h = href                           (b) h = h ref +80m     Figure 5. Imaging simulation results of target P on the reference plane. 
 Breit, G., and M. A. Tuve: A Test of the Existence of the Conducting Layer, Phys. 
 ,",  
 SUITED FOR  APPLICATION IN CIVIL MARINE RADARS USED ON SMALL PLEASURE BOATS OR LARGE COMMERCIAL  SHIPS )TS SUCCESS HAS BEEN DUE IN PART TO THE RADAR NEEDING ONLY SMALL TRANSMITTER POWER  AND THE RADAR DOES NOT REQUIRE DOPPLER PROCESSING TO SEPARATE MOVING TARGETS FROM LARGE FIXED CLUTTER ECHOES 4HUS  MANY OF THE PROBLEMS THAT OCCUR WITH MAGNE 
 The most widely used and generally successfld ofthe resulting equipments was theSCR-584. Before beginning precision tracking ofasingle target, aradar that is toserve asthe only equipment ofanantiaircraft battery must execute a general search inorder tolocate targets that are tobetracked and engaged. Noauxiliarv long-wave radar search equipment was provided \vith the SCR-584. 
 TION OF THESE CHANNEL 
 TRAFFIC CONTROL L 0ULSE COMPRESSION L -ONOPULSE TRACKING RADAR WITH GOOD TRACKING ACCURACY AND BETTER RESISTANCE TO ELEC 
  AND CROSS 
 The output noise power will fluctuate continually and irregularly above and below itsaoer-age value, the latter being understood asan average taken over atime long enough toinclude very many fluctuations. An example that iseasy todiscuss quantitatively isthe following. Suppose that theintermediate frequency amplifier isfollowed byasquare- law detector and byfurther (video) amplification instages whose pass band issobroad astointroduce nodistortion ofthe signal. 
 Appleton had  been the first to measure distance by radio waves when  | he. devised, early in the 1920's, a means of measuring  . THE DISCOVERY OF RADAR 21  the height of the Heaviside layer, that ionized layer of  atmosphere about sixty miles up from the earth’s sur-  face. 
 Meteorol. , vol. 15, pp. 
 1969, Malvern, England.  94. Hlacksrnitli. 
 114-120, January, 1958. 114.Bates.R.H.T.:Random ErrorsinAperture Distributions, IRETrailS.,vol.AP-7,pp.369-372. Octoher. 
 .This is called the interference region since the direct wave and  474INTRODUCTION TORADAR SYSTEMS strength ofthewindandthedistance andtimeoverwhichthewindhasbeenblowing. Thusthe seaintheNorthAtlantic isnotthatmuchdifferent fromtheseaintheSouthPacificifthe wind conditions arethesame.Landclutter,ontheotherhand,ishighlydependent onthenatureof theterrainandthelocalconditions. Urbanareas,cultivated fields,forests,mountains, desert, andtundraallcanproduce different radarechoes.Furthermore, radarscattering fromlandis affected byrain,snowcover,thetypeofvegetation orcrops,thetimeofyear,thepresence of streams andlakes,andman-made objectsinterspersed amongtheterrain.Therecanbe considerable variability inbothlandandseaclutter.Thisinherent variability mustbeunder­ stoodandproperly accounted forinradarsystemdesign. 
 AP-32, pp. 295-296, March 1984. 79. 
 78. R. W. 
 107 Itiscommon practice tobegin thedesign ofapulser around aresist- ance load equal tothestatic resistance oftheactual load tobeused atits required operating point. Although final evaluation ofthe pulser per- formance requires consideration ofthe whole system and particularly of the oscillator used, much information about pulser behavior can be obtained byconsidering apure resistance load. The following discussion ofthetypes ofpulsers inuseatpresent and their characteristics isbased onthe assumption ofaresistance load. 
 Some of these considerations are influenced by the advantages that attach to employ - ing multiple simultaneous receive beams, so a broad but well-shaped transmit beam  that can be filled by perhaps 10 to 30 narrow receive beams is a popular choice. In the  limiting case, the transmit array may floodlight the entire sector of coverage, which is  filled with receive beams that stare continuously. The nonuniformity of clutter sources  can cause serious problems with any design that does not have control over the array  pattern. 
 Inthe present case Ajwas chosen as40Xfc/see, which corresponds toah=6ft,and so,because ofaveraging, toarather smaller operational error. The mean transmitter frequency isnow chosen. This must be fairly high inorder tokeep. 
 124 INTRODUCTION TO RADAR SYSTEMS  I  60 -----------·----+ -t-- al 50 - ------- -0  0 u 40 2  20  10  01......~~~-L-~~J.-~l-.....!_-L..-L.....J-......Jl---~~~-L-~~.L.-~1..-'""""::::i:::...L_L_.l__J  0.001 0.01 0.1  Clutter spectral width/radar prf . 5  4, 6  3, 7  2,8  Figure 4.24 Improvement factor for each filter of an 8-pulse doppler filter bank with uniform weighting as  a function of the clutter spectral width (standard deviation). The average improvement for all filters is  indicated by the dotted curve. 
 Vertical polarization might be preferred when complete vertical coverage is required. Horizon-  tal polarization might be specified when enhanced range capability is desired and complete  vertical coverage is not necessary. The theoretical curves of Fig. 
 Four unknown parameters of the measured area were estimated, and the time-series deformation results of the measured area were inverted eventually. Through an analysis of the results, we found that the higher the elastic modulus and viscosity were, the lower the deformation was. It can also be concluded that the overall temporal characteristics of the time-series deformation showed a non-linear trend of variation, with a gradual decrease of subsidence velocity in the early stage and a small recovery in the later stage. 
 The performance of the SLB may be analyzed by looking at the different outcomes  obtained as a consequence of the pair ( u, v) of the processed signals (see Figure 24.1 b). FIGURE 24.1 a Main and auxiliary antenna patterns for the SLB ( after  L. Maisel42 © IEEE 1968 ) FIGURE 24.1 b Scheme of sidelobe-blanking system ( after L. 
 H. Wang, H. Park, and M. 
 These  transistor parameters define the transfer characteristics in the I-V (current-voltage)  plane, and the boundaries of the I-V plane define the peak power performance enve - lope of the transistor. Also, there is an optimum load impedance that will maximize the  power output that can be delivered from an amplifier; and to a first order estimate, that  load impedance is represented by the line that transversely cuts across the I-V plane  from the region of the breakdown voltage to the region of the knee voltage, as shown  in Figure 11.4. The ability of a transistor to demonstrate gain at high frequencies is  impacted by the mobility and saturated velocity of charge carriers in the semiconduc - tor. 
 In particular the conical  shape can present a serious polarization problem since the polarization varies with the direc­ tion of propagation. Another problem is that the radiating elements can see dilTerent environ­ ments depending on their location on the cone. The pattern of the conical array cannot be  separated into elevation and azimuth patterns. 
 Ships, balloons, towers, etc.).   Examp les with the corresponding Radar backscattering diagrams are shown in Figure 11.16.     Figure 11.16  “Cluster” reflectors. 
 if the pilot is approaching too far to the right of the  runway a series of dashes will be heard in the intercom,  and broad echoes will show up on the CRT.  As he changes course to the left the broad echoes  become shorter, and small, narrow responses or ‘dot’  signals will appear. Any deviation to one side or the  other immediately produces corresponding changes in  the echo blips. 
 Ifthesawtooth has anamplitude small compared toE—that is, ifRC>>T—the rise isapproximately linear (Waveform 3). Such saw- tooth generators are widely used incases where nogreat precision is required. When various sweep speeds aretobeused, itisnecessary tochange therate ofrise ofthesawtooth. 
 CARRIER NOISE SIDEBANDS PRESENT ON THE SAMPLE CLOCK SIGNAL ARE  TRANSFERRED TO SIDEBANDS ON THE SAMPLED INPUT SIGNAL  REDUCED BY LOG F  F3  D"  &OR EXAMPLE  IN AN )& SAMPLING APPLICATION WITH THE INPUT SIGNAL Ð OF THE SAMPLE FREQUENCY  THE CLOSE 
 All rights reserved  “ERIS BOOK IS PRODUCED IN  COMPLETE CONFORMITY WITH THE  AUTHORIZED ECONOMY STANDARDS  ————$—  Componed in Plantin type and printed by Western Printing Services, Lid,  . EDITOR’S FOREWORD  ARRAP’S TORCH BOOKS” ARE INTENDED TO SERVE A  wide public with accurate, up-to-date science in-  terestingly arranged and illustrated, each book written by  an author experienced in explanation and well qualified  in his subject.  Having regard for the reader’s comfort and conveni-  ence, the authors have made the treatment popular;  having an equal regard for his intelligence, they have  included the fundamentals, without which any know-  ledge of a subject is worthless. 
 1 !(H) 1 106. Novcr~ihcr. 1975. 
 RADAR RECEIVERS  6.416x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 A/D converter. The required A/D converter SNR to avoid saturation on the interfer - ing signals is given by  SNR d BP C NI ADC ADC( ) log =  10102  (6.44) where  PI = interference power at A/D converter input  C = crest factor  NADC = A/D converter noise The crest factor is the peak level that can be handled within the full-scale range  of the A/D converter relative to the rms interference level. It is set to achieve a   sufficiently high probability that full-scale will not be exceeded. 
 The curves plot received power versus normal - ized doppler (i.e., in units of the Bragg frequency) for eight radar operating  frequencies. The peak at zero frequency is due to a stationary target in an  antenna sidelobe. ch20.indd   75 12/20/07   1:17:15 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Their performance  can be calculated or measured in a simple phased-array simulator, 7 2• 73 and good performance  can be obtained with a well-designed radiator. The waveguide might be loaded with dielectric  to reduce its physical size in order to fit the element within the required space. Ridge-loaded . 
 By analyzing the Do p- pler shift, targets, which lay 20 – 30 dB under the clutter lever, can be discovered and s e- lected.  There are even examples for the detection of signals smaller by 70 - 90 dB.  Circuits,  which distinguish these echoes of mov ed targets from the clutter, are designated as Moving  Target Indicators (MTI). 
 These are the clutter fence and the Kalmus clutter filter.  Kalmus clutter filter.s9 This is a technique for extracting moving targets, such as a walking  person or a slowly moving vehicle, from land clutter whose doppler-frequency spectrum masks  that of the moving target. A moving target will produce a doppler-frequency shift that is either  at a lower or a higher frequency than the transmitted signal. 
 Therefore, if the  cliaracteristics of tlic target cross section are not properly taken into account, the actual  perforrna~ice of tlie radar niight riot measure up to the performance predicted as if the target  cross sectiori were constant. Figure 2.22 also indicates that for probabilities of detection  greater than about 0.30. a greater signal-to-noise ratio is required when the fluctuations are  uncorrelated scan to scan (cases 1 and 3) than when tlie fluctuations are uncorrelated pulse to  pulse (cases 2 and 4). 
 Maines, J. D., and E.G. S. 
 The FM waveform in the block diagram of Fig. l l.14 is generated by directly modulating  the high-power transmitter. It is not always convenient to directly modulate a transmitter in  this manner. 
 8.2 Table 8.1collects andsummarizes allthese applications. TABLE 81.-SUMMARY OFPRINCIPAL L’SES OFBEACONS Radar orIother interrogator Ground (fixed) Ground I Shipborne Pllotage Airborne Navigation Blind ap- proachShipborne Identification Identification Identification HomingBeacons .Airborne Portable Identification Surveying Ground-controlled precise navigation Control ofaircraft Liferafts Homing Shore bombardment Identification Temporary marking Rendezvous ofpoints onland Liferafts 8.2. Systems Planning.-Given aparticular radar set, itissimple enough toprovide abeacon forany special use. 
 16.King,R.W.P.,andT.T.Wu:"TheScattering andDiffraction ofWaves," Harvard University Press. Cambridge, Mass.,1959. 17.Crispin, J.WooJr.,andK.M.Siegel:"Methods ofRadarCross-Section Analysis," Academic Press, NewYork,1968. 
 PASS POLARIMETRIC )N3!2 SINGLE 
 The  . 20 HOW RADAR WORKS -  wonder is that the U.S. Navy Department, for whom  Taylor and Young were working then as civilian scien-  tists, did not make more immediate use of their impor-  tant discovery. 
 ~r:\~.¥!rqIUl~-\' ''''·#-I+I~i.'H+-Hf--v-l+-lTl ~-04;i;I·"·,:I:I:" ,.I,,'"UMliJ\1 IIfT~',l, ~I...r ~.,,'';1', !I I ~If!,,!VliIi'W.Ii I"T11 . _ L.~ 111 .... II " I I I,fI ! " 1 I:J -0.6 I' I'I Ii'\I! II' .T·II,. 
  
 Before design characteristics can besuccessfully crystallized, regardless oftheorigin ofaproposal, there must beanextensive interplay ofideas and ofinformation between specialists inthe following categories: (1) application specialists representing thepotential using organization, who must contribute necessary information ondesirable performance char- acteristics, limitations onsize, weight, and power consumption, and limitations onthe number and skill ofoperators and maintenance men; (2)component specialists, who must contribute information onthestatus ofdevelopment and onthelimitations ofthemany component parts that make upacomplete system; (3)system specialists with experience inthe design and operation ofradar systems. Normally aman experienced insystem design isbest able tocoordinate the over-all development project. Hemust have asupporting group of experienced systems men toassist onthedesign problem and tocarry out operational test work that may bedesirable, and hemust have the con- tinued advice and support ofspecialists ofthe first two categories listed above. 
   #)6), -!2).% 2!$!2   ÓÓ°x "ECAUSE PRECIPITATION CLUTTER IS DISTRIBUTED IN A RELATIVELY UN IFORM MANNER  PASSING  THE RECEIVED WAVEFORM THROUGH A DIFFERENTIATOR GIVES PROMINENCE TO TARGETS EMBEDDED  WITHIN THE CLUTTER BY ENSURING THAT THE AVERAGE CLUTTER LEVEL IS KEPT WELL BELOW SATURA 
 The detection of signals and the extraction of information are not totally indepen-  dent processes since either one without the other is meaningless.  This chapter discusses some of the concepts involved in the extraction of information  from a radar signal. The next section considers in a qualitative manner the type of target  information available from a radar signal. 
 NAL APPLICATION 4HUS  A TACTICAL APPLICATION DEVELOPER NEED NO T HAVE KNOWLEDGE OF THE  UNDERLYING RADAR PROPAGATION MODELING TECHNIQUES OR OTHER ENVIRONMENTAL CONSIDER 
 E. Telford: Estimation of Tropospheric Refractive Bending from Atmos- pheric Emission Measurements. Radio Science, vol. 
 The grid isbeyond cutoff and rising exponentially toward the bias potential. The plate isatB+potential. Attime t,thetube begins toconduct, the plate begins tofall, byvirtue oftheinductive coupling thegrid ispulled upward, and aviolently regenerative action sets inwhich ultimately pulls the grid far positive, drawing much current from the cathode. 
 There are three approaches to the analysis of this type of radar: the phasor diagram, the time-frequency plot, and Fourier analysis. One should have some facility with each. Perhaps the most useful attack for an FM radar having modest deviation is the phasor diagram. 
 PULSE CORRELATION AND OPTIMIZING FILTER BANDWIDTHS !)3 
    
 The bistatic radar can be operated with either a pulse modulation or CW, just as can a  rnonostatic radar. The simplicity of CW or modulated CW has an advantage in the bistatic  radar, not usually enjoyed by rnonostatic radar. A CW radar requires considerable isolation  between transtnitter arid receiver to prevent the transmitted signal from leaking into the  receiver, Isolation is obtained in the bistat ic radar because of the inherent separation bet wee11  t rarisniitter and receiver. 
 The rnonostatic radar is the more versatile of the two because of its ability to scan  a hernisplierical voluriie in space and because of the relative ease with which usable target  information can be extracted from the received signal. Another advantage of monostatic radar  is that o~ily one site is required as compared with the two sites of the bistatic radar. Thus a  bistatic-radar system might be more expensive than a monostatic radar of comparable detec-  tion ability since the cost of developing the additional site (building roads, sleeping quarters,  mess facilities, etc.) can be a significant fraction of the total. 
 Mexico city land subsidence in 2014–2015 with sentinel-1 iw tops: Results using the intermittent sbas (isbas) technique. Int. J. 
 $$# ARCHITECTURE CAREFULLY IN THE FREQUENCY DOMAIN  3UPPOSE A REAL )& SIGNAL IS ONCE AGAIN CENTERED AT  -(Z AND SAMPLED AT  -(Z AS IN LINE A  OF &IGURE  4HE FIRST THREE LINES OF &IGURE  ILLUSTRATE THIS IN THE FREQUENCY DOMAIN WITH LINE  SHOWING THE SAMPLED )& SIGNAL 4HE BANDPASS FILTER RESPONSE ON LINE  REMOVES THE UNWANTED SPECTRAL COMPONENTS TO PRODUCE THE COMPLEX PASSBAND SIGNAL OF LINE  4HIS SIGNAL IS THEN DECIMATED BY  AND SHIFTED BY n -(Z TO PRODUCE  AT A  -(Z SAMPLING RATE  THE DESIRED COMPLEX BASEBAND SIGNAL SHOWN ON LINE  &IGURE  SHOWS THE CORRESPONDING BLOCK DIAGRAM 4HE MAGNITUDE OF THE FRE 
 SES  WHICH MAY BE FIBER OPTIC OR WIRED 4HE PROGRAMMABLE DEVICES ARE CONTROLLED BY SOFTWARE OPERATING ENVIRONMENTS INVOKING PROGRAMS 4HE ARCHITECTURE OBJECTIVE IS TO HAVE STANDARD INTERFACES  FEW UNIQUE ASSEMBLIES  AND SINGLE 
 TO 
 RATED !LTHOUGH PITCH AND YAW MOTIONS ARE SLOWER  THEY ALSO EXIST AND ALLOW SEPARATION IN OTHER SIMILAR PLANES 2EASONABLY GOOD IMAGES COUPLED WITH EXPERIENCED RADAR OPERATORS ALLOW RECOGNI 
 A discussion of HF radar may be found in Chap. 24. At the other end of the potentially useful radar spectrum, in the millimeter-wave band, the few published measurements of radar clutter lead to the conclusion that millimeter-wave backscatter behaves in much the same manner as backscatter at the lower microwave frequencies. 
 Using a short pulse width is one way to improve distance  resolution . However,  shorter  pulses  contain  proportionately  less  energy, preventing reception at greater range due to  propagation  losses. Increasing  the transmit  power is  impractical   in many cases, such as for aircraft radar  due to power  constraints. 
 Paul Lebenbaum, Jr.,“Altitude Rating ofElectric Apparatus,” Transactions AIE.E,63,955-960 (December, 1944). D.Ramandanoff andS.IV.Glass, “High-altitude Brush Problem,” l’ransactions .41EE,63, W$829 (November, 1944). Howard M.Elsey, “Treatment ofHigh-altitude Brushes, ”Transactions All?.!? (.kugust, 1945).. 
 Thus the use of solid-state transmitters can have an  effect on other parts of the radar system. At millimeter wavelengths very high power  can be obtained with the gyrotron , either as an amplifier or as an oscillator. The grid- control vacuum tube  was used to good advantage for a long time in UHF and lower  frequency radars, but there has been less interest in the lower frequencies for radar . 
 338-340, October, 1958.  63. Hammer. 
 - -ULTIPATH 
 BAND INTERFERENCE  INCLUDING REJECTION AT THE 2& IMAGE FREQUENCY !FTER DOWNCONVERSION TO  )&  A BANDPASS FILTER PROVIDES REJECTION OF UNWANTED SIGNALS AND SETS THE RECEIVER ANA 
   #HINA )NSTITUTE OF %LECTRONICS    PP n  'UEST EDITORIAL AND INVITED PAPERS REVIEWING /4( RADAR TECHNOLOGY  WITH EMPHASIS ON RECENT  PROGRESS  2ADIO 3CIENCE  VOL   *ULYn!UGUST   ! ! +OLOSOV ED    &UNDAMENTALS OF /VER 
 IRE , vol. 48, pp. 1630–1635, September 1960. 
 Anglefluctuations areduetorandom changes intherelativedistance fromradartothe scaUerers, thatis,varyingvaluesofCi..Thesechanges mayresultfromturbulenc.e intheaircraft. I;i~t~rc 5.13 Plot of tiq. (5.2). 
 Alexnet with ﬁne-tuning. 302. Sensors 2019 ,19,6 3 3. 
   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°ÓÇ #OMPENSATION FOR 3CANNED )MPEDANCE 6ARIATION  4HE IMPEDANCE OF AN ELE 
 J. Frazer and S. J. 
 M. Weiner, Chapter 9,2 courtesy SciTech ) (Continued ) ch23.indd   25 12/21/07   10:50:26 AMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
  
 Eadan, and R. Gassner, “Comparison of robustized assignment algorithms,” SPIE ,  vol. 3068, pp. 
 I.:DigitalMTIRadarFilters,IEEETrans.vol.AU-16, pp.422-432, September, 1968. 23.Taylor. J.W.Jr.amiJ.Mattern: Receivers. 
 TION DIFFERENCE SIGNAL  AND AZIMUTH DIFFERENCE SIGNAL ARE EACH  CONVERTED TO INTERMEDI 
 The transmitter ‘triggers  off’ the rest of the radar equipment, and just at that  instant the light-spot in the tube is cut off. This results  in the beginning of the ‘trace,’ or line of light, not being  permanently cluttered up with the bright, unnecessary  blip caused by the home station, which may confuse the  accurate spotting of weak echoes near home.  We are still troubled with echoes from fixed objects  . 
 FREQUENCY(MHz) (b) FIG. 19.6 Target spectra of the baseband (folded or ambiguous) receiver (a) and the off- set video (unambiguous) receiver (b) indicate the limitation which clutter harmonics im- pose on the achievable range of target velocities which can be handled. tending the speedgate's frequency coverage to cope with faster targets and at- tempts to eliminate—or at least attenuate—clutter required additional conver- sions, which, even with the introduction of solid-state circuitry to replace vacuum tubes, resulted in prohibitive increases in size, complexity, and reduced reliability.2'6 Inverse Receiver.2-6-14 The major breakthrough was the introduction of the inverse receiver, which gets its name from the fact that the bandwidth "funnel" of the conventional receiver (wide IF, narrower doppler amplifier, final narrowband speedgate) is inverted, with the final narrow banding (speedgating) placed right after the first conversion from microwave to IF. 
 7AVE 0OWER %LECTRONICS   .EW 9ORK )%%%  0RESS AND 7ILLEY )NTERSCIENCE    3EC   7 ( 9OCOM  h(IGH POWER TRAVELING WAVE TUBES 4HEIR CHARAC TERISTICS AND SOME APPLICATIONS v  -ICROWAVE *  VOL   PP n  *ULY   ! 3 'ILMOUR  *R   0RINCIPLES OF 4RAVELING 7AVE 4UBES  "OSTON  -! !RTECH (OUSE      3EC   ( ' +OSMAHL  h-ODERN MULTISTAGE DEPRESSED COLLECTORS! 2EVIEW v  0ROC )%%%  VOL     PP n  .OVEMBER   ! 3 'ILMOUR  *R   -ICROWAVE 4UBES  .ORWOOD  -! !RTECH (OUSE    3EC   - * 3MITH AND ' 0HILLIPS  0OWER +LYSTRONS 4ODAY  .EW 9ORK *OHN 7ILEY    3EC   ! % 3TAPRANS  7 -C#UNE  AND * ! 2UETZ  h(IGH 
   PP n    0 ( 9 ,EE  * $ "ARTER  + , "EACH  % #APONI  # , (INDMAN  " - ,AKE  ( 2UNGALDIER   AND * # 3HELTON  h0OWER SPECTRAL LINESHAPES OF MICROWAVE RADIATION BACKSCATTERED FROM SEA SURFACES AT SMALL GRAZING ANGLES v  )%% 0ROC 
 !#'& ) &$'&#'& 
  7(Z 4O ACCOUNT FOR THE ADDITIONAL NOISE INTRODUCED  BY A PRACTICAL NONIDEAL  RECEIVER  THE THERMAL NOISE EXPRESSION IS MULTIPLIED BY THE  NOISE FIGURE  &N OF THE RECEIVER  DEFINED AS THE NOISE OUT OF A PRACTICAL RECEIVER TO THE  NOISE OUT OF AN IDEAL RECEIVER &OR A RECEIVED SIGNAL TO BE DETECTABLE  IT HAS TO BE LARGER THAN THE RECEIVER NOISE BY A FACTOR DENOTED HERE AS  3.   4HIS VALUE OF SIGNAL 
 ONLY FILTERING 3!2 USUALLY INVOLVES WIDEBAND PROCESSING  REQUIRING FOR ADAPTIVE NULLING TECHNIQUES  PECULIAR ALGORITHMS %FFICIENT BROADBAND JAMMER NULLING HAS TO BE COUNTERED WITH SPACEFAST 
 "ASED -6$2 ALGORITHM FOR  ADAPTIVE MULTIPULSE ANTENNA ARRAY SIGNAL PROCESSING v  )%% 0ROC  VOL   PT &  NO   PP n   !PRIL   0 "OLLINI  , #HISCI  ! &ARINA  - 'IANNELLI  , 4IMMONERI  AND ' :APPA  h12 VERSUS )12  ALGORITHMS FOR ADAPTIVE SIGNAL PROCESSING PERFORMANCE EVALUATION FOR RADAR APPLICATIONS v )%% 0ROC  VOL   PT &  NO   PP n  /CTOBER   ! &ARINA AND , 4IMMONERI  h2EAL TIME 34!0 TECHNIQUES v  %LECTRONICS  #OMMUNICATIONS  %NGINEERING *OURNAL  3PECIAL )SSUE ON 34!0  VOL   NO  PP n  &EBRUARY . Ó{°ÈÓ  2!$!2 (!.$"//+   0 +APTEIJIN  % $EPRETTERE  , 4IMMONERI  AND ! &ARINA  h)MPLEMENTATION OF THE RECURSIVE 12  ALGORITHM ON A   #/2$)# TEST 
 OUTPUT )/   AND CONTROL MODULES ! SIMILAR DESIGN CONCEPT IS USED FOR THE ELECTRO 
 TO 
 Sevgi, A. Ponsford, and H. C. 
 If the plot had been in terms of the angle 0, the lobes would have been found to increase in width as 101 increased. The main lobe occurs when sin 0 = O. The other lobes have the same amplitude as the main lobe and are referred to as grat- ing lobes. 
 42 
 (6.15) is halved in deci- bels. (a) (b) FIG. 6.9 Parabolic cylinder, (a) Geometry, (b) Extension. 
 Thinned Arrays.  The number of radiating elements in an array may be reduced  to a fraction of those needed completely to fill the aperture without suffering serious  degradation in the shape of the main beam. However, average sidelobes are degraded  in proportion to the number of elements removed. 
 BIAS  WHEREIN THE TRANSISTOR DRAWS COLLECTOR CUR 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo.  GROUND ECHO  16.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 between ground area and projected area. 
 FIG.9S.-A scanner witha60-in. shaped cylindrical reflector, ventrally installed inaB-29. Inthis figure thelinear feed isimagined perpendicular totheplane ofthe drawing. 
 (Note that this is the same as the  3pectrum ofa pulse of sine wave, the only difference being the relative value of the duration 6.)  In marly instances, the echo is not a pure sine wave of finite duration but is perturbed by  fluctuations in cross section, target accelerations, scanning fluctuations, etc., which tend to  CWANDFREQUENCY-MODULATED RADAR75 Transmitflng antenna ~CW ~---;E------J transmifter fa fa Figure3.4Blockdiagram ofCWdoppler radarwithnonzero IFreceiver, sometimes calledsideband Sliperlleterodpie. consists oftwosidebands oneithersideofthecarrierplushigherharmonics, anarrowband filterselectsoneofthesidebands asthereference signal.Theimprovement inreceiversensi­ tivitywithanintermediate-frequency superheterodyne mightbeasmuchas30dBoverthe simplereceiverofFig.3.2. Receiver bandwidth. 
 The resonant wave or Bragg peaks are marked A for approaching and R for receding. The peak at zero frequency is due to a stationary target in an antenna sidelobe. and Chrisman,53 and it is quite flexible, permitting antenna and target altitudes, surface conductivity and permittivity, polarization, and frequency to be speci- fied. 
 This is contrary to what would normally be expected if the clutter were  uniform. J  Thus, as the resolution cell size is decreased the nature of the sea clutter changes. The  changes can have a profound effect on radar performance. 
 ‘.. ..,’” ‘.. FIG.2.15.—Propagation within aduct (overeimplified). 
 TION AND TRACKING PERFORMANCE OF A RADAR SYSTEM $ETECTION PERFORMANCE IS MEASURED BY THE PROBABILITY OF DETECTION TRACKING PERFORMANCE IS DETERMINED BY THE PROBABILITY OF DETECTION AND THE PROBABILITY OF FALSE ALARM AS WELL #ONVENTIONAL CELL AVERAGING  #&!2 RAISES THE THRESHOLD IN THE PRESENCE OF NOISE JAMMING AND REDUCES THE NUMBER OF TARGETS DETECTED (OWEVER  THE TARGETS THAT SURVIVE CAN BE EFFECTIVELY TRACKED BECAUSE THE PROBABILITY OF FALSE ALARM HAS BEEN MAINTAINED AT SUFFICIENTLY LOW LEVELS 7ITHOUT #&!2 AND APPROPRIATE THRESHOLD ADJUSTMENTS  PERHAPS NO TARGETS WILL BE TRACKED DUE TO THE VERY LARGE NUMBER OF FALSE PEAKS DETECTIONS ON THE JAMMER   MAKING IT THROUGH TO SATURATE THE TRACKER #ONVENTIONAL #&!2 IS NOT REALLY REMOVING THE INTERFERENCE IT IS JUST hHIDINGv IT FROM THE RADAR OPERATOR (OWEVER  IT IS ALLOWING THE TRACKER TO OPERATE  p  4HIS IS USED WITH "ARKER CODES  FOR INSTANCE  WHERE THE AMPLITUDE LIMITATION DOESNT IMPAIR THE PHASE CODE. Ó{°ÎÈ  2!$!2 (!.$"//+  EFFECTIVELY FOR THE TARGETS THAT SURVIVE  AND SO IN THIS WAY  IT CAN PREVENT THE OVERALL  FAILURE OF THE RADAR )N THE LIMIT OF NO TARGETS BEING DETECTED IE  A VERY POWERFUL JAM 
 This figure of merit is more representative of a "search lighting"  radar and not a surveillance radar.  Ground-wave 0TH radar. The type of 0TH radar described in the above that propagates via  refraction from the ionosphere is sometimes called a sky-wave radar. 
 #HEBYSHEV FILTER BANK Ó°££Ê * 
 In addition, impervious surface fraction is an index that measures the level of urban construction [ 50]. 215. Sensors 2019 ,19, 743 3. 
 Skolnik, Introduction to Radar Systems , 3rd Ed., New York: McGraw Hill, 2001, pp. 355–57.  45. 
 TO 
 Since y will then be fixed, the denominator p(y) will be constant  and the a posteriori probability is  where the constant k is determined by the normalizing condition; that is, the integral of  p(SN I y) over all possible values must be unity. Therefore, if the a priori probability p(SN) is - .  known, the a posteriori probability may be found directly from Eq. 
 SIPATION WITHIN THE 2& STRUCTURE ITSELF 4HE EFFICIENCY OF A 474 IS USUALLY LESS THAN THAT OF A KLYSTRON BECAUSE OF THE LOSS DUE TO THE ATTENUATION OF THE SEVERS  AS WELL AS BY THE PRESENCE OF RELATIVELY HIGH 2& POWER OVER AN APPRECIABLE PART OF THE ENTIRE STRUCTURE ! TECHNIQUE FOR IMPROVING THE EFFICIENCY OF HIGH 
 Von Aulock, W. H.. and C. 
 Altliougti the TWT and the klystron are similar in many respects, one of the major  dinerences between ttie two is that feedback along the slow-wave structure is possible in the  TWT, but the back coupling of RF energy in the klystron is negligible. Ifsufficient energy were  fed back to the input, the TWT would produce undesired oscillations. Feedback energy might  arise in the TWT from the reflection of a portion of the forward wave at the output coupler. 
 11–17, 1982. 122. R. 
 75-82, November 1977.  73. Waldman, J.: Millimeter and Submillimeter Wave Receivers, U.S. 
 Both of these waveforms have  their areas of application; but in the past, the linear FM, or chirp, pulse compression has  probably been more widely used. The time sidelobes of the phase-coded pulse are of the order  of 1/ BT. The peak sidelobe of the chirp waveform is generally higher, but at a slight sacrifice in  signal-to-noise ratio it can be made low by means of weighting networks. 
 DOMAIN '02 ARE LIMITED TO LINEAR PHASE  DESIGNS SUCH AS RESISTIVELY LOADED DIPOLES  4%- HORNS  OR )MPULSE 2ADIATING !NTENNAS )2!S  )T SHOULD BE NOTED THAT ULTRAWIDEBAND ANTENNAS FALL INTO TWO CLASSES  THOSE THAT RADIATE A REASONABLY SHORT IMPULSE WITH LOW TIME SIDELOBES AND  FUNDAMENTALLY POS 
 If the earth is perfectly absorptive (a thermodynamic blackbody), its effective noise temperature may be assumed to be approximately 290 K. A suggested conventional value for Tag is 36 K, which would result if a 290 K earth were viewed over a ir-steradian solid angle by sidelobes and back- lobes averaging 0.5 gain (-3 dB). These sidelobes are typical of a "good" radar antenna but not one of the ultralow-noise variety. 
 LOG AMPLIFICATION  AS  WELL AS PROCESSES IN THE DIGITAL DOMAIN )NTIMATELY CONNECTED WITH THRESHOLDING STRATE 
 This has led to the development of numerous techniques for estimating  and removing the various forms of signal corruption.95–97 As an alternative, Trizna98  and Pilon and Headrick99 have reported a method for estimating s ° from simple mea - surements made directly on the corrupted radar echo spectrum. While this approach  may be relatively insensitive to some forms of corruption, it is not applicable to seas  far from equilibrium. All the methods for estimating sea state or scattering coefficients require long  coherent integration times, usually combined with noncoherent averaging of a number  of CITs in order to achieve a distinct and stable spectrum. 
 14. pp. 1584- 1593. 
 Note that in these curves, for each value of elevation angle 0, the antenna boresight is assumed to be directed exactly on the target. Thus, in the absence of ground reflections, the net field strengths in A and B would have been equal for all values of 0. The corresponding off-boresight errors for the amplitude curves of Fig. 
  615 G% (QWURS\ G%   ))7 5(/$; $3(6 3URSRVHG Figure 7. Entropy curves with di ﬀerent algorithms. From Figure 7, it can be seen that the entropies of all the algorithms are decreasing with the increase of SNR. 
 This high order is required for focusing data acquired at high squint angle and at high resolution along very variable aircraft trajectories. In this case, indeed, the inertial navigation system is not able to provide positioning, velocity and angle information accurate enough for a reliable SAR focusing. The method was used for processing both simulated data and real airborne data, and provided accurate targets focusing, thus demonstrating the reliability of high order Doppler parameter compensation. 
 OF 
 SPACE-BASED REMOTE SENSING RADARS  18.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 a radar, especially aboard a spacecraft. Because a radar by definition must transmit,  its near-field radiation is a potential threat to all other instruments and subsystems  of the host spacecraft and its payload. Once having got past the risk (or paranoia) of  near-field radiation, normal spacecraft design principles kick in. 
  DETECTOR  7HILE NOISE MAY BE NON 
 16. Ogg, F. C., Jr.: Steerable Array Radars, IRE Trans., vol. 
 DELAY CANCELER .   -4) 2!$!2  Ó°ÎÇ "ECAUSE THESE CURVES SHOW THE SIGNAL 
 IED THE 0  0  0  AND 0 POLYPHASE CODES   4HESE CODES ARE STEP APPROXIMATIONS  TO THE ,&- PULSE COMPRESSION WAVEFORMS  HAVE LOW 
 §  The main beam and sidelobe clutter received by airborne radars can have quite different doppler shifts due to  the movement of the platform with respect to the ground resulting in the angle-doppler coupling of the clutter.  However in OTH radar, main beam and sidelobe clutter from a single ionospheric mode typically have simi - lar doppler spectrum characteristics because the radar is stationary. This means that sidelobe clutter appears at  roughly the same doppler shift as main beam clutter and doppler filtering can be used effectively for detecting  targets usually without special need to reject the sidelobe clutter spatially. 
 Lacking such data, wecan only venture the opinion, based onpersonal observation, that the location didnotappear unusual inany way-in fact itappears likely that moun- tain areas with even higher ground returns may becommon. The width ofthe rejection bands depends onthe variability ofthe ground returns. Until now, the ground returns have been assumed constant, sothat the voltage atPoint 1inFig. 
 The two pieces are joined bya beryllium copper “bullet” which issoldered into one piece and makes tight contact with the inner surface ofthe other bymeans ofexpanding prongs ontherounded tip. Inorder totransfer r-fpower toarotating scanner, arotary joint for acoaxial line isnecessary. Early designs involving wiping contacts on (a) (b) FIG. 
 For the air volume surveillance mission, electronic scanning provides flexibil- ity and performance not readily available in electromechanical scanners. These advantages include (1) shorter volume surveillance frame times; (2) highly flexi- ble computer-programmable waveform versus elevation time and energy manage- ment; (3) electronic compensation for moving platforms and mobile applications such as ground vehicles, ships, and aircraft; and (4) wide and flexible elevation coverage, including highly agile beam placement in elevation, programmable el- evation coverage versus range and azimuth, good beam shape preservation over wide coverage, and flexible, precise control of beam placement versus azimuth, which is especially critical for low-elevation-beam performance. Frequency Scanned Radars. 
 In some cases, frequency agility can also be uti- lized to decorrelate clutter and integrate ship target returns. Scan-to-scan video cancellation can be utilized for detecting moving targets overland if their scan- to-scan motion is of the order of the radar pulse width. REFERENCES 1. 
 E. Brookner, “Phased-array around the world. Progress and future trends,” IEEE Int. 
 Torres and D. S. Zrnic, “Whitening in range to improve weather radar spectral moment   estimates. 
 :L∑∑ ∑. comparator   Figur e 12.2  Principle of the CA -CFAR circuit.     12.1.3  The OS -CFAR   ACUT 321samples of the digital signalSUT-TVcomparator target identification. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.656x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 FIGURE 20.34  Radar performance estimate for July 0800 UTC,   SSN =10 FIGURE 20.35  Radar performance estimate for July 1800 UTC,   SSN = 10 ch20.indd   65 12/20/07   1:17:09 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 nearby  land clutter can be so large that it can enter the radar via the antenna sidelobes and degrade  performance. At vertical incidence there is less backscatter from land than from sea, but this is  usually undesirable since it reduces the range of radar altimeters over land.  Land clutter is difficult to quantify and classify. 
 ING BETWEEN THE ORBITAL PASSES )DEALLY  THE RADAR WAVELENGTH PROJECTED ONTO EACH AREA OF THE SURFACE MUST BE THE SAME FROM BOTH ORBITS 3INCE THE TWO ORBITS ARE SEPARATED  EACH AREA IS OBSERVED AT A SLIGHTLY DIFFERENT INCIDENT ANGLE 4HIS IMPLIES THAT THE EFFEC 
 TIVE THRESHOLDING METHOD ASSUMES THAT THE NOISE DENSITY IS KNOWN EXCEPT FOR A FEW UNKNOWN PARAMETERS EG  THE MEAN AND THE VARIANCE  4HE SURROUNDING REFERENCE CELLS ARE THEN USED TO ESTIMATE THE UNKNOWN PARAMETERS  AND A THRESHOLD BASED ON THE ESTIMATED DENSITY IS OBTAINED .ONPARAMETRIC DETECTORS OBTAIN A CONSTANT FALSE 
 TORING SEASONAL VARIATIONS 3UITABLE APPLICATIONS INCLUDE SEA ICE COVER  LARGE ICEBERGS  CONTINENTAL ICE SHEETS  VEGETATION  AND SOIL MOISTURE n. £n°xÈ  2!$!2 (!.$"//+  &LIGHT 3YSTEMS 2AD3CAT 4ABLE   WAS THE NAME GIVEN TO THE RADIOMETER SCATTEROMETER PORTION OF THE 3 
 185- 192, October, 1955.  38. Withers. 
 SCATTEROMETER 2!$3#!4   AND WITH  TRUCK 
 28. Davies, I. L.: On Determining the Presence of Signals in Noise, Proc. 
 DOPPLER CELL  THE PROBABILITY  OF DETECTION  0D  OF A GIVEN LOOK CAN BE DETERMINED FOR A GIVEN TARGET 3.2  THE NUM 
 The straighter and  more upright the sides, like the figure LI, the sharper  will be the start of the pulse and the more sudden its  cessation, and this gives us the radio version of the  staccato shout. This pulse can be formed by combina-  tions of radio oscillating circuits, the first of which pro-  duces a sine wave, or similar wave-form, with rounded  edges and faces; and in subsequent circuits the wave-  form is sharpened and straightened until it becomes  almost what is known as a square wave. Most of the  pulses in radar circuits are, in fact, varieties of square  waves, very different indeed from the sine-wave forms  handled by the stages of broadcast receivers. 
 Straiton, A. W., and C. W. 
 The damping network reduces the trailing edge of the pulse and prevents  post-pulse oscillations which could intrQduce noise or false targets.  Hard-tube modulator.1 The hard-tube modulator is essentially a high-power video pulse  amplifier. It derives its name from the fact that the switching is accomplished with "hard­ vacuum" tubes rather than gas tubes. 
 20. P. A. 
 Techniques  exist for reducing the undesired effects of altitude holes, but not without some inconvenience  or possible loss in overall performance.44 . 94 INTRODUCTION TO RADAR SYSTEMS  The Janus system can be operated incoherently by using the same transmitter to feed a  pair of beams simultaneously. Typically, one beam is directed ahead and to the right of the  ground track, and the other aft and to the left. 
 [ CrossRef ] 27. Liu, A.K.; Hsu, M.K. Deriving ocean surface drift using multiple SAR sensors. 
 It is not possible to single out any one individual as the inventor; there were  many fathers of radar. This was brought about not only by the spread of radio technology to  many countries, but by the maturing of the airplane during this same time and the common  recognition of its military threat and the need to defend against it.  .'  1.6 APPLICATIONS OF RADAR  Radar has been employed on'the ground, in the air, on the sea, and in space. 
 15.29  Empirical Filter Design  .......................................  15.29  Chebyshev Filter Bank  .......................................  15.31  Fast Fourier Transform Filter Bank  ..................... 
 VERSUS 
 REFLECTOR COMPACT RANGE CONFIGURATION 
 70.) By locating the center of the n puls_es, an estimate of the target's  angular direction can be obtained. This is called beani sp/itti11g.  If there is but one target present within the radar's coverage, then detections on two scans  are all that is needed to establish a target track and to estimate its velocity. 
 Atmospheric turbulence as well as deliberate maneuvers result in the aircraft trajectory  (14.16)522INTRODUCTION TORADAR SYSTEMS wherePr=peaktransmitted power Ae=effective aperture oftherealantenna a=targetcrosssection n=numberofpulsesintegrated (coherently) l=wavelength kTo=4x10-21W/Hz B=receiver bandwidth Fn=receiver noisefigure R=range Thisequation ismodified bysubstituting Pr=PaJr.l~, wherePa\,=average power,r=pulse width ~l/B,andJp=pulserepetition frequency. Also/I=.I~to, whereto=Le/t,=time required togenerate thesynthetic aperture whoselengthisgivenbyLe=RA.ID,v=velocityof thevehiclecarrying theradar,andD=real-antenna dimension. Forlow-grazing angle a=aObcrbrsect/Jwhere(To=radarcrosssectionofthegroundperunitareailluminated, c5cr=along-track, orcross-range, resolution (equaltoDI2forafocused SAR),fl,=range resolution, andt/J=grazing angle.Substituting theaboverelations intoEq.(14.14)yields PayA;aobrsect/J SIN=8nlkToF nl'R3- (14.15) Thisisessentially thesameequation asgivenbyCutrona2andHarger.J Equation (14.15)doesnotincludetheambiguity constraints described previously. 
 An example  is the Hawk tracking illuminator shown in Fig. 3.3. It is a tracking radar as well as an  illuminator since it must be able to follow the target as it travels through space. 
 DUCE IMAGES THAT CLOSELY RESEMBLE AERIAL PHOTOGRAPHS "OTH SHADOWS AND DIFFER 
 Inparallel polarization thespacing must be held accurately inorder toprevent distortions ofthewavefronts; slender spacing posts areused since they have almost noeffect onthewaves. In. SEC. 
 Mar. 7. 1957. 
 DELAY BINOMIAL -4) . 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 minor error contributions to scattered energy (random errors) or misdirected radia - tion (systematic errors) become significant. In practice, peak sidelobe levels as low  as −30 to −35 dB (average level, −5 to −20 dB) can be readily realized with phased- array antennas that electronically scan. 
 The receiver portion of such an il- luminator is very much like the seeker described in the following sections. The main differences stem from the much higher feed through levels in which the illu- minator receiver operates and from the previously mentioned doppler spectrum differences (i.e., outbound targets are below feedthrough). Alternatively, the illuminator can be the transmit-only portion of a radar slaved to a tracking radar—a mechanically scanned track-while-search (TWS) ra- dar or a phased array which simultaneously maintains multiple target tracks with its electronically steered agile beam. 
 TION BUT ARE UP TO  '(Z GIGAHERTZ  AND COULD BE  '(Z IN THE NEAR FUTURE 3ENSOR  PROCESSING HAS ARRIVED AT THE POINT WHERE THE CONCEPTION OF SUCCESSFUL ALGORITHMS IS MORE IMPORTANT THAN THE COMPUTATIONAL HORSEPOWER NECESSARY TO CARRY THEM OUT -&!2 3OFTWARE 3TRUCTURE  )MPROPER OPERATION OF MANY FIGHTER SYSTEMS  CAN BE HAZARDOUS !S PREVIOUSLY MENTIONED  THE SOFTWARE MUST BE EXHAUSTIVELY  TESTED  ERROR CHECKED  MATHEMATICALLY TRUSTED  FAILSAFE IN THE PRESENCE OF FAULTS  AND EMBODY STRICT PROGRAM EXECUTION SECURITY /NE OF THE MOST IMPORTANT ASPECTS IS RIGID ADHERENCE TO A STRUCTURED PROGRAM ARCHITECTURE !N OBJECT 
 H. Boot, and The High-power Pulsed Magnetron,  by W. B. 
 Kogon, “Algorithms for mitigating terrain-scattered interference,” Electronics &  Communications Engineering Journal , vol. 11, no. 1, pp. 
 Hansen, “Performance of the analog moving window detection,” IEEE Trans ., vol. AES-6,  pp. 173–179, March 1970. 
 For the X-band case, let VM = 2000 ft/s and VT = 500 ft/s in level flight. MLC will then be at roughly 40 kHz and the target at 50 kHz. If the target were flying away from the missile at the same 500 ft/s velocity, its doppler fre- quency would be 30 kHz, or 10 kHz below MLC. 
    WAS SIMILAR TO 3EASAT  BEING AT , BAND  WITH AN ( 
 W. H. (ed.): Special Issue on Conformal Arrays, IEEE Trara.. 
 Withascancapability of±60°,aminimum ofthreeplanaraper­ tures,orfaces,arerequired tocoverthehemisphere. Butwhenotherfactorsareconsidered, morethanthreefacesareusuallydesired. Thegreaterthenumber offaces,thelesswillbethe lossingain,beambroadening, VSWRvariation, polarization change, andthenumha of elements perface.Otherfactorswhichmustbeconsidered inselecting theoptimum Ilumber of facesarethenumberoftransmitters andreceivers, thecomplexity ofthecontrolofthearray, andthetotalcost. 
 Two measurement sets are of interest: in plane, where <|> = 180°, and out of plane, where <|> < 180°. When <|> = 180°, P = 9, - 9/. In the monostatic case p = O and 95 = 9, with <|> = 180°. 
 The lower tlie frequency the easier it is to  obtain long range. However, at the lower frequencies, the azimuth beamwidths are broader  and the available bandwidths are narrower than might be desired. Below UHF, the external  noise increases wit11 decreasing frequency and can limit receiver sensitivity. 
 CALLY ENCOUNTERED WAVE FEATURES  PERHAPS LASTING A FEW SCANS SUCH AS A TRAVELING WAVE CREST  NEED TO BE EMPLOYED -ANUAL SELECTION IS EFFECTIVELY A PLOT EXTRACTION PROCESS OPERATING OVER A SMALL AREA SURROUNDING THE CURSOR !N ALPHA 
 Between these two points, that is,onthe downward slope ofthe curve, regulation will be unstable. The slope ofthe curve tothe left ofthe peak isless than that tothe right ofthe valley, giving better regulation. However, in this region thecarbon pile isunder less pressure, and isthus more suscepti- FI~.14.11.—Output waveform showing amplitude modulation. 
 Radars with high resolution might  actually he capable of better performance than predicted on the basis of a Rayleigh cluiter  model and a cr0 independent of radar resolution. A radar with a narrow pulse width or narrow  beamwidth not only sees less land clutter than a radar with larger pulse width or beam­ width, but it can see targets in those areas where clutter is less than the average, if these areas  can be resolved. Jn practice, there are regions of land where the clutter might be considerably  greater than the average and regions where it is considerably less than average. 
 TO 
 The pulse doppler radar, on the other hand, has a high pulse repetition  frequency that avoids blind speeds, but it experiences ambiguities in range. It performs doppler  MTIANDPULSE DOPPLER RADAR139 employed inthenoncoherent MTIreceiver, elsethedesiredamplitude fluctuations wouldbe lost.Therefore theIFamplifier mustbelinear,orifalargedynamic rangeisrequired, itcan belogarithmic. Alogarithmic gaincharacteristic notonlyprovides protection fromsaturation, butitalsotendstomaketheclutterfluctuations atitsoutputmoreuniform withvariations in theclutterinputamplitude [Sec.(13.8)].Thedetector following theIFamplifier isaconven­ tionalamplitude detector. 
 KNOWN PRECEDENT.   30!#% 
 The target appears as two closely  spaced blips which approximate a short bright line, the slope of which is in proportion to the sine of  the angle of target elevation.  I-scope. A display in which a target appears as a complete circle when the radar antenna is pointed at it  and in which the radius of the circle is proportional to target distance; incorrect aiming or the  antenna changes the circle to a segment whose arc length is inversely proportional to the magnitude  or the pointing error. 
    0FA    
 NATED AREA )N FACT  EVEN FIXED RADARS FREQUENTLY OBSERVE FLUCTUATIONS IN GROUND ECHOES BECAUSE OF MOTIONS OF VEGETATION  WIRES BLOWING IN THE WIND  ETC 4HIS FLUCTUATION IS REFERRED TO AS FADING &ADING IS SIGNIFICANT FOR THE RADAR ENGINEER BECAUSE ONE MUST ACCOUNT FOR THE FACT  THAT A SINGLE SAMPLE OF THE RADAR RETURN MAY VARY WIDELY FROM THE MEAN DESCRIBED BY R   4HUS  THE SYSTEM MUST BE ABLE TO HANDLE THE  DYNAMIC RANGE OF FADING   WHICH MAY  EXCEED  D" 2EGARDLESS OF THE MODEL USED TO DESCRIBE A GROUND SURFACE  SIGNALS ARE  IN FACT   RETURNED FROM DIFFERENT POSITIONS NOT ON A PLANE !S A RADAR MOVES PAST A PATCH OF GROUND .   '2/5.$ %#(/  £È°£Î WHILE ILLUMINATING IT  THE LOOK ANGLE CHANGES  AND THIS CHANGES THE RELATIVE DISTANCES TO  DIFFERENT PARTS OF THE SURFACE THE RESULT IS THAT RELATIVE PHASE SHIFT IS CHANGED 4HIS IS THE SAME KIND OF RELATIVE 
 (6) Refer- ence signal derived from the drive of the conical-scan feed. antenna changes azimuth. A target flying a passing course by the radar will, at its closest point to the radar, cause the azimuth servo to drive faster at high eleva- tion angles than at low elevation angles. 
 Daley, J. C., J. T. 
 %$)'%"%")  ,  
 A,Band Care the coefﬁcients determined by the transmit direction and geomagnetic ﬁeld whose expression has been discussed in Carrano’s work [ 27].θ(κ)is the incident angle of beam center correlates to the spatial wavenumber. In our work, the spatial variant incident angle is applied as a modiﬁcation for the original Rino spectrum and the scintillation phase screen is then derived based on the modiﬁed phase spectrum in Equation ( 19). 4.4. 
 An interesting technique for graphically portraying the variation of the beam shape with  scan angle has been described by Von Au lock, 15 an example of which is shown in Fig. 8.3. The  antenna radiation pattern is plotted in spherical coordinates as a function of the two direction  cosines, cos ax and cos a}., of the radius vector specifying the point of observation. 
 5. IJavenport. W. 
 RANGE RESOLUTION CELL DIMENSION  ,2  AT RANGE  2 IS GIVEN  BY ,2 $yK WHERE $ IS THE RECEIVING ARRAY APERTURE AND  K IS THE RADAR WAVELENGTH  )  -)#2/7!6% 2!$!2))  (& 3+97!6% 2!$!2 4YPE CHOSEN FOR COMPARISON ,ONG 
 Ransone, Jr., and J. A. Burkett: Radar Sea Return-JOSS I, Naval Research  Laboratory Report 7268, Washington, D.C., May 11, 1971. 
 Three-coordinate, or 3D, information can be obtained on each rotation  of the radar by electronically scanning a single pencil hearn in elevation wllilc n~~~llii~li~ally  rotating the antenna in azimuth. The beam is rapidly scanned tllro~tgh  coverage in the time the antenna rotates pne-azimuth beamwid*.  -- - -/ obtained by the sequential scanningol a single kcmas  multiple -_ -.-_-- beams described in the above. 
 Aperture-frequency dispersion, often expressed in terms of aperture-bandwidth  product37,59,63  4. The limited bandwidth of the majority of the schemes implementing Eq. 24.3, as  compared with the wideband of a barrage jammer that can be regarded as a cluster,  spread in angle, of narrowband jammers  5. 
 C. Schleher, “Radar detection in log-normal clutter,” in IEEE Int. Radar Conf ., Washington,  DC, 1975, pp. 
 Many of the advantages of frequency agility can be obtained if the radar frequency  shifts pulse-to-pulse the minimum amount required to decorrelate successive echoes. The  minimum frequency shift is equal to the reciprocal of the pulse width. Slow tuning rates can be  used, but the pulse-to-pulse frequency might not appear random. 
 These losses  are very real and cannot be ignored in any serious prediction of radar performance. The loss  due to the integration of many pulses (or integration efficiency) has already been mentioned in  Sec. 2.6 and need not be discussed further. 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .536x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 FIGURE 7.44  Radar detections o and DF detections collected on the control aircraft. The os,  ∆s, +s, and xs are radar detections on four aircraft of opportunity in the vicinity of the control  aircraft. 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7   blind folio 7 .58 ch07.indd   58 12/17/07   2:15:11 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 G ACCELERATION 4HIS SAME TECHNIQUE CAN BE APPLIED TO MANY DIFFERENT RADAR 
 Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 Amplitude Characteristics.  To predict the performance of an MTI system, the  power of the clutter returns with which a target must compete should be known. 
 02& WAVEFORM IS USED TO DETECT  TARGETS COMPETING WITH SIDELOBE  CLUTTER THAT WOULD BE UNDETECTABLE IN (273 -273  ALLOWS THE DETECTION OF NOSE ASPECT TARGETS AT WIDE SCAN ANGLES THAT ARE CROSSING THE RADAR LINE 
 This value, plus the required dynamic for the measurement of 30 dB to 60 dB, yield the required decoupling between the transmitting and receiving sectors of 130  dB to  200 dB.  The procedures for measuring scalar RCS will not be further discussed, instead, in the following the concentration will be on polarimetric RCS determination.   11.4.2  Measurement of The Complex Polarization Scattering M a- trix  The Radar signature of scattering objects, expres sed by the complex RCS σ, is a function of  various parameters:   σ = ƒ(frequency, polarization, aspect angle)  . 
 The magnitude of cosmic noise depends  upon the portion of the celestial sphere in which the antenna points. It is a maximum when  looking toward the center of our own galaxy, and it is a minimum .vhen observing along the  pole about which the galaxy revolves. A plot of the maximum and minimum cosmic-noise  brigl~trtess tentperattire as a function of frequency is shown by the dashed curves of Fig. 
  3PIRIT  FACED THE  SAME PROBLEM WITH ENGINE PLACEMENT THAT ,OCKHEED DID WITH THE & 
       4IME OF DAY 54 . Óä°{È  2!$!2 (!.$"//+  HAVE BEEN SHOWN TO SUPPORT SPATIALLY COHERENT PROCESSING  (ENCE  THE RECEIVING  ARRAY APERTURES OF SKYWAVE RADARS MAY RANGE FROM ^  KM FOR SYSTEMS CONCERNED  ONLY WITH AIRCRAFT AND BALLISTIC MISSILES TO MORE THAN  KM IN SYSTEMS DESIGNED FOR SHIP DETECTION AND TRACKING 4AKING  KM AS A RECEIVE APERTURE  CONVENTIONAL BEAMWIDTH AT  -(Z IS ^   SO  SIMULTANEOUS BEAMS SPAN ^   WHICH SETS THE REQUIRED TRANSMIT APERTURE IN THIS EXAMPLE AT n M  DEPENDING ON THE VARIATION IN GAIN THAT CAN BE TOLERATED ACROSS THE SET OF RECEIVE BEAMS 4HE MOST VERSATILE BEAMFORM 
 THE 
 The ﬁrst work on airborne radar was undertaken at the Bawdsey Research Station, at Bawdsey Manor in Suffolk [ 5–7],ﬂying from Martlesham Heath. At the outbreak of war the team, now part of the Air Ministry Research Establishment (AMRE), moved ﬁrst to Perth and then, in October 1939, to RAF St Athan. RAF St Athan was home to 32 Maintenance Unit (No. 
 K. M.: I'c~forrii:ir~cc of a Watcl--l<cpcllc~~t Radorlic C'o;ttirig iri an Airpol-t Surveillatice  K;ldnr, /'roc.. IEEE, vol. 
 Arra)" radar S)"Stem functions. An array radar is sometimes required to perform more than one  function with the same equipment. The problem with a multifunction array is to utilize  effectively the resource of time and the resource of radar energy. 
  !())!     !+ '"%"%(!)!%$!$ ) ""!) ( "%))   +  *!    $) $$  ,   , %&&" '  $) $$ %!$)!$   $ " (*"( %"'!,)!%$ '$(#!)*"( '!   ' , %'  '$ 
 The effect of polarization on a0 also depends on  the wind, as mentioned below.  Variation with wind.Iw4 Except at grazing angles near normal incidence, the value of a0  increases with increasing wind speed. The backscatter is quite low with winds less than about  5 knots, increases rapidly with wind speeds from about 5 to about 20 knots, and increases  less rapidly at higher wind speeds.' An example is shown in Fig. 
 of Geophysical Research , vol. 83, pp. 3459–3468, 1978. 
 High peaking causes a large overshoot and a return to the target  with additional overshoot. In the extreme (as in system A shown in Figure 9.15 b),  the antenna zeros in on the target with a damped oscillation. An optimum system  compromise between speed of response and overshoot, as in system B, allows the  antenna to make a small overshoot with reasonably rapid exponential movement back  to the target. 
 AP-8,  pp. 276-285, May, 1960.  75. 
 Presumming   is the formation of an unfocussed synthetic beam (i.e., there is little or no attempt to  match the exact phase history of surface points) inside the real antenna beam by what  is essentially a lowpass filter. This would result in different target brightness and con - trast if it were not compensated by applying a corresponding post detection integration  (PDI) for each angle, as shown in Figure 5.33. Multiple frequency looks are used to reduce speckle in the image and so several  different frequencies are PDIed. 
 L. Rubin, Radar Detection,  Norwood, MA: Artech House, Inc., 1980,  pp. 287–445. 
 Liu, Y.Y.; Zhao, C.Y.; Zhang, Q.; Yang, C.S.; Zhang, J. Land subsidence in Taiyuan, China, monitored by insar technique with multisensor sar datasets from 1992 to 2015. IEEE J. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°È£ MODE WAS DESIGNED TO MEASURE SUBSURFACE HORIZONS IN THE LUNAR DIELECTRIC CONSTANT  IN BOTH SIDE 
 (a,b) San Francisco dataset; ( c) ground truth; ( d) NR-ELM; ( e) GaborTLC; ( f) PCAKM; (g) proposed method. 272. Sensors 2019 ,19, 2605 T able 2. 
 TURES OF THIS REFLECTOR INCLUDE ITS PRECISE SURFACE ACCURACY  HIGH STIFFNESS AND STABILITY  LOW MASS  AND RELIABLE DEPLOYMENT &OR EXAMPLE  FOR THE REFLECTOR SHOWN IN &IGURE   AN 2-3 SURFACE ACCURACY OF LESS THAN  MILS FROM ALL ERROR SOURCES INCLUDING IN 
 Thedetection performance of themoving-window detector isabout0.5dBworsethantheoptimaldetector whichweights thereturned signalsbythefourthpoweroftheantenna voltagepattern.63Theangular loca­ tionofthetargetcanbeestimated fromtheoutputofthisdetector bytakingthemidpoint between thefirstandlastcrossings ofthedetection threshold, orbytakingthemaximum value oftherunning sum.Aftercorrecting forthebias,theaccuracy ofthelocation measurement is onlyabout20percentworsethantheoretica1.63 Recirculating-delay-line integrator.65·70Thedelay-line integrator, ormoving-window detec­ tor,described aboverequires thatanumberofpulses,equaltothatexpected fromthetarget, beheldinstorage. Asimplification canbehadbyrecirculating theoutputthrough asingle delayline(Fig.to.toa)whosedelayisequaltothepulserepetition period.Therecirculating- Topped delayline ~~g'O"d output Figure10.9Pulseintegrator usingtappeddelayline.. Loop gain = k < 1  71  Input .- -9-- 1-1 -J  J. 
 The   line 3 signal is created in the time domain as  [line 3] = [line 1] e−j2p  fLOt   = [line 1] cos(2 p  fLOt)    –j[line 1] sin(2 p  fLOt)   = [I3   + jQ3]  FIGURE 25.9  Typical analog downconversion to baseband  and digitizerLPF LPFADC ADCQIANALOG   DIGITAL 16 16 QI 50 MHz IF LO  GENERATOR  (75 MHz)–SIN COS ch25.indd   7 12/20/07   1:39:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 
 The step-scan transmitter remedy increases the surveillance frame time by the number of required transmit beam steps. This increase is usually not acceptable for surveillance operations, and as a consequence the remedy is seldom consid- ered. The multibeam-receiver remedy restores the frame time but increases re- ceiver cost and complexity, since a multiple-beam antenna is required and an RSP must be used for each beam. 
 TO 
           .   2!$!2 $)')4!, 3)'.!, 02/#%33).'   Óx°ÓÎ A VARIETY OF FUNCTIONS  INCLUDING SINE  COSINE  VECTOR ROTATION PHASE SHIFT   POLAR 
 Table 5.1 shows the range of parameters that  can be observed as a function of radar mode. The parameter ranges listed are PRF,  pulse width, duty cycle, pulse compression ratio, independent frequency looks, pulses  per coherent processing interval (CPI), transmitted bandwidth, and total pulses in a  Time-On-Target ( TOT). Obviously, most radars do not contain all of this variation, but modes exist in many  fighter aircraft, which represent a good fraction of the parameter range. 
 PULSE STAGGERING PRODUCES DOPPLER COMPONENTS IN THE PASSBAND OF THE -4) FILTER 0ULSE 
 60. R. B. 
 15.53  Pulse Compression Considerations  ....................  15.55  15.12 Analog-to-Digital Conversion Considerations  .........  15.57  Dynamic Range  ................................................. 
 MIL-6, pp. 130-139, April 1962. 7. 
                    # "# !  "!!  ". 
 ELECTRONIC COUNTER-COUNTERMEASURES  24.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 signals and/or to emphasize the desired signal or signals in the summing network  output. Output signal Z is envelope-detected and compared with a suitable thresh - old a to detect the presence of a useful target (see Chapter 5 in Farina34 and other  sources.53–57,83,84) The adaptive array is a generalization of the SLC described in the  preceding subsection. The basic theory of jammer cancellation and target enhance - ment is considered first; attention is then focused on the following topics: main-beam  jammer cancellation, target DoA estimation in presence of jammer, two-dimensional  adaptive processing for joint clutter and jammer cancellation, adaptivity at the subar - ray level, and superresolution. 
 The binary quantization of line lengths makes it convenient to apply digital techniqiies  for actuating the shifter.  Figure 8.6 shows the schematic of a four-bit digital phase shifter consisting of four  cascaded modules. Each module contains a switch that inserts either "zero" phase change or a  phase change of 36012" degrees, where n = 1,2,3,4. 
 TARGET DETECTOR 4HE PULSE PAIR CONSISTS OF A  
 SCAN OR LOBING MODULATION IS IMPOSED ON BOTH THE TRANSMITTER AND THE RECEIVER BEAMS  IT IS RELATIVELY SIMPLE FOR A JAMMER TO SYNTHESIZE THE APPROPRIATE JAMMING SIGNAL BY INVERTING AND REPEATING THE TRANSMITTER MODULATION INVERSE 
 This phenomenon can also be observed in Figure 7. The lower right portions of Figure 7a,b are brighter than the other area is. This indicates that the wind direction determines the brightness variations of the overall SAR image. 
 ING TARGET v 0ROC TH )NT 3YMP 3IGNAL 0ROC !PPL  "RISBANE  !UGUST   PP n  9 :HANG  - ' !MIN  AND ' * &RAZER  h(IGH 
 BY 
 , 
 30. D. K. 
 *  The compensation required by ∆G2(q )/2 can be determined from a Taylor’s series expansion of G2(q ). In the pre - ceding discussion, we used the first derivative. Using higher-order terms gives an improved correction signal. 
 source supplying the clamping point must be“stiff” enough tofllrnish thecurrents drawn without appreciable potential change. Among thesimple switched clamps arethediodes ofFig. 13.23a, the. 
 Attempts to use a schnorkel buoy to represent a schnorkelgave detection ranges of only about 3 nmi, against an expected range of better than 6 nmi. In retrospect, this highlighted the contribution to the signal of a real schnorkel of the wake and wave splashing seen with a submarine underway,together with the ﬂuctuations in depth keeping that would have given periodic increases (and fades) in the radar return. A sea return discriminator was ﬁtted and found to reduce the extent of the sea return. 
 FORM AND THE METHOD OF GENERATION AND PROCESSING -ETHODS OF GENERATING AND PROCESS 
 When c = ±45°, the polarization is circular, with +45° for left-hand and −45°   for right-hand. When 0 < | c | < 45 °, the polarization is elliptical. Analytically, the electric field may be described as  E = Eh1h + Ev1v (16.25) where 1h and 1v are unit vectors in the h and v directions. 
 WAVE CONTRIBUTION DUE TO LONG  SMOOTH SURFACES IS ONE OF THE EASIEST TO SUPPRESS %VEN SO  THE THICKNESS AND GEOMETRIC DISTRIBUTION OF SURFACE 
 In principle, riiultiple receiving beams can be generated utilizing the Fast Fourier Trans-  form (FFT) proce~sor."~ If the output of each receiving element is sampled at the Nyquist  rate and if tlie sampled voltages are converted to a digital number, the FFT processor may be  used to generate ~iiultiple beams digitally, just as the Butler beam-forming array generates  then1 in analog fashion. Ttius the antenna beams are generated by computation. Its practical  inipleliieritation rcqi~ires coriverting RF or IF signals at each elernent to digital numbers. 
 IEE, pt. 111, vol. 93, pp. 
 This will be discussed first, and the  effect of the feed will follow. Aperture Effects.  When energy is incident on an array at an angle other than  broadside (Figure 13.24), the phase required on the edge element is y   = (2p L)/l sin q0. 
 The rotating antenna may use a continuous waveform processed  through either a finite-impulse-response (FIR) filter or an infinite-impulse-response  (IIR) filter, or may use a batch waveform consisting of coherent processing intervals  (CPIs) that are processed in FIR filters in groups of N pulses. (The term MTI filter ,  used often in this chapter, is a generic nomenclature that includes both FIR and IIR  filters.) The finite time-on-target dictates the need for a batch processing approach. There are many different combinations of successful MTI techniques, but any spe - cific MTI radar system must be a total concept based on the parameters of the antenna,  transmitter, waveform, signal processing, and the operational environment. 
 2 the radar detection process was described in terms of threshold detection.  Almost all radar detection decisions are based upon comparing the output of a receiver with  some threshold level. If the envelope of the receiver output exceeds a pre-established threshold,  a signal is said to be present. 
 Hansen, R. C.: Tables of Taylor Distributions for Circular Aperture Antennas, I RE Trans.,  vol. AP-8, pp. 
 Harrison. A.: Marine Radar Today -A Review, Tlie Radio and Eleclronic Engineer, vol. 47. 
 RANGE (& OVER 
 New York. 1947.  2. 
 LIKE WAVEFORMS  AND RELATIVELY WIDE BANDWIDTHS n 7HEN THESE BROADCAST TRANSMITTERS ARE APPROPRIATELY SITED AND  OPERATING  THEY CAN SUPPORT MANY TYPES OF SURVEILLANCE  PARTICULARLY AIR SURVEILLANCE  WHICH IS OFTEN RESTRICTED FOR MONOSTATIC RADARS OPERATING AT 6(&5(& 4HE SURVEILLANCE CAN BE COVERT BECAUSE EVEN THE TRANSMITTER IS UNAWARE IT IS BEING EXPLOITED AND CAN BE COUNTER 
 STATE TRANSMITTER IS DISCUSSED IN #HAPTER   AND A BRIEF COMPARISON OF IT WITH THE VACUUM TUBE TRANSMITTER IS GIVEN AT THE END OF THIS CHAPTER  4HE CHIEF ADVANTAGES OF A SOLID 
 Likewise all  the elements which lie in the same row utilize the same phase shift to steer the beam in  elevation. The phase shift at the rr~t~th element therefore is the sum of the phases required at the  r?rtti colunin for steering in azimuth and at the 11th row for steering in elevation. This summa-  tion can be m6de at the computer and distributed to the MN elements of the array. 
 35. Miller, E. K., G. 
 2017 ,55, 3408–3425. [ CrossRef ] 10. Li, D.; Lin, H.; Liu, H.; Liao, G.; Tan, X. 
 335-348, June, 1946; also discus­ sion by II. J. Riblet, vol. 
 Radar frequency was  · 13.4 MHz producing .t resonant doppler frequency shift of 0.3 7 Ht. The dopplcr frequency scale has heen  normalized so that tile Jominant components are at ± I. AR W = approach resonant wave; RR W =  recede resonant wave calibration signal is at left of tigure. 
 Transmit carrier frequency diversity dwell-to-dwell forces Swerling  I and III target fluctuation statistics and improves cumulative probability of detec - tion performance. Frequency diversity look-to-look within a dwell produces Swerling  II and IV statistics and is better suited for high single-scan probability of detection. ch04.indd   37 12/20/07   4:53:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 848–856, August 1965. 27. J. 
 153. A. I. 
 Good contact between thebottom ofthecover and thebaffles isobtained bytheuseof screws which pass through thecover and aretapped into thebaffles. The i-fstrip requires apower supply giving 65ma at+105 volts unregulated for plates and screens, 1.4 amperes at6.3 volts a-c for heaters, and avoltage variable from Oto–10volts (with asource. 468 THERECEIVING SYSTEM—RADAR RECEIVERS [SEC. 
 R. W. Larsen, A. 
 128 C-W RADAR SYSTEMS [SEC. 5.1 target. Itisassumed that thetarget ismoving radially, thus supplying theneeded modulation. 
 51.Ferguson, P.,andR.D.Dokken: ForHigh-Power Protection ...TryMultipacting, Microwaves, vol. 13,pp.52-53,July,1974. 52.Goldie,H.:Radioactive (Tritium) IgnitorsforPlasmaLimiters,lEEE Trans.,vol.ED-19,pp.917-928, August, 1972. 
 ITY AND UNDERGO REDISTRIBUTION ACROSS WAVENUMBER SPACE THROUGH THE MECHANISM OF NONLINEAR WAVE INTERACTIONS TO PRESERVE THE EQUILIBRIUM SPECTRAL FORM 4HERE ARE A NUMBER OF MODELS THAT HAVE BEEN PROPOSED TO DESCRIBE THE EQUILIBRIUM  SPECTRAL FORM  AND INDEED  MODELS THAT ATTEMPT THE MORE AMBITIOUS TASK OF MODELING NONEQUILIBRIUM SPECTRA -OST OF THESE MODELS ARE BASED ON EXPERIMENTAL MEASURE 
    -ARCH     2 ( !BRAMS  " ,EVUSH  ! ! -ONDELLI  AND 2 + 0ARKER  h6ACUUM ELECTRONICS FOR THE ST  CENTURY v )%%% -ICROWAVE -AGAZINE  PP n  3EPTEMBER    ! . +OROLYOV  % ! 'ELVICH  9 6 :HARY  ! $ :AKURDAYEV  AND 6 ) 0OOGNIN  h-ULTIPLE 
 CALLY INSTALLED ON A TRIAL VESSEL FOR SUCH TESTS OR USE A LAND SITE OVERLOOKING THE SEA 4HIS SCENARIO IS BECOMING INCREASINGLY UNSATISFACTORY AS ADVANCES IN REQUIREMENTS  FOR SAFETY AND THE PROTECTION OF THE ENVIRONMENT MEAN THAT IT IS NECESSARY TO ENSURE THAT TYPE APPROVAL IS CONSISTENTLY APPLIED AND IS  THEREFORE  MEASURED IN A QUANTITATIVE MAN 
 15.13  Filter Mismatch Loss  ..........................................  15.14  Clutter Visibility Factor (V OC)  ..............................  15.14  15.5 Improvement Factor Calculations  ........................... 
 Pixel B and pixel C are anisotropic because both are man-made metal structures. After obtaining the RCS curves of the pixels, the aspect entropy can be calculated. Figure 11 is the aspect entropy image of the full scene. 
 The interval may  be changed on a pulse-to-pulse, dwell-to-dwell (each dwell being a fraction of the  beamwidth), or scan-to-scan basis. Each approach has advantages. The advantages  of the scan-to-scan method are that it is easier to build a stable transmitter, and mul - tiple-time-around clutter is canceled in a power amplifier MTI system. 
 Now examine Fig. 2.6binwhich theaverage oftwo noise traces isplotted, each point ihone trace being averaged with the corresponding point inthe other. The fluctuations are here less violent. 
  AND !.&01 
 Ifapencil beam moves upordown because ofmaneuvers ofthe aircraft orpoor stabilization, the scope signal will fade. Quantitatively, ifabeam moves upordown byone-half itsbeamwidth, itcan beshown that thesetwill suffer arange reduction of29percent. The range will bereduced 10percent ifthebeam varies from the stabilized position by0.28 beamwidth and by5percent ifthe beam varies 0.19 beamwidth. 
 WAY HALF 
 PROTECTION DECOY IS MOST LIKELY TO BE USED BY LARGE FIGHTERATTACK AND BOMBER AIRCRAFT 4HE 30 DECOYS ARE EXPENDABLE OR TOWED %XPENDABLE DECOYS ARE EJECTED OR DROPPED  FROM THE AIRCRAFT WHEREAS TOWED DECOYS ARE TETHERED BEHIND THE AIRCRAFT %XPENDABLE DECOYS CONTAIN MINIATURE JAMMING SYSTEMS THAT ARE SMALL ENOUGH TO FIT INTO A STANDARD CHAFFFLARE DISPENSER 4HE DECOY ORIENTS ITSELF TO THE AIR STREAM BY DEPLOYING LOW 
 RMS NOISE  TO THE  CANCELER WAS CHANGED FROM   TO  D" BETWEEN THE  TWO PICTURES !N AIRCRAFT FLYING OVER THE CLUTTER IN THE FIRST  MI IN THE LEFT 
 DOPPLER SPACE IS A FUNCTION OF THE RADAR ALTITUDE  SPEED  AND ANTENNA SIDELOBE LEVEL )F A HIGH 
  3 
 25-Oct. 1, 1977. 50. 
 The reader, ttowcvcl., wilt find only a fcw pagcs of  the original edition that have not been modified in some manner.  One of the features of the first edition which Ilas hcen contintled is the inclt~sion of  extensive references at the end of each chapter. These are provided to acknowlcdgc the sources  of material used in the preparation of the book, as well as to permit the interested reader to  learn more about some particular subject. 
 MENTS HAVE BECOME MORE DEMANDING  SO THE EQUIPMENT  TECHNIQUES  AND DATA PROCESS 
 RECEIVER PATHS )N VIEW OF THE FAMILIARITY OF SPACE WAVE PROPA 
 138. G. Petrocchi, S. 
 It consists of five  layers. There are two outer skins, a center skin, and two intermediate cores. It is used when the  ordinary A sandwich does not provide sufficient strength. 
 SURFACE IMPULSE RESPONSE   &IGURE   3EA 
 X. Shou, J. Xu, H. 
 The average voltage across the resistor, pro- portional tothe average rate ofchange ofthe difference frequency, is measured byavoltmeter. Headphones assist intheidentification ofthe frequency ofany modulation that may exist. Tomeasure thestability ofacoherent oscillator, itisallowed torun freely. 
 Themeasurements made bythetwosystems arenotthesame;consequently, thecharacteristics oftheantenna beams willalsobedifferent. Intheamplitude-comparison monopulse thetwobeamsarcoffset,thatis, pointinslightly different directions. Thistypeofpattern maybegenerated byusingone reflector dishwithtwofeedhornssidebyside(fourfeedhornsfortwocoordinate data).Since thefeedsmaybeplacedsidebyside,theycouldbeascloseasonc-half wavelength. 
 105-108, March, 1968.  108. Pelton, E. 
 The bistatic angle , b = qT − qR, is the angle between the transmitter  and receiver with the vertex at the target. It is also called the cut angle  or the scattering  angle . It is convenient to use b in calculations of target-related parameters and qT and qR  in calculations of transmitter- and receiver-related parameters. 
 Recortl, vol. 8, pt. I,  pp. 
 AES-3,  EASCON’67 Tech. Conv. Rev, November, 1967, pp. 
 VERSUS 
 Trial Report No. 44/36, 15th August 1944 (TNA AIR 65/123) [4] ASV Mk. 7 A, ARI. 
 Therefore, the typical air defense active missile employs some form of PD transmission and coherent processing to re- solve and track the target in doppler (velocity) and sometimes also in range. The active PD seeker can be thought of as a miniature airborne fire control radar. The waveform selection tradeoffs, especially the clutter-waveform inter- actions, are the same in the active seeker as in the airborne intercept (AI) radar. 
 Let the weights applied to the outputs  of the N taps be:  W _ e-1121t(i-1)k/NJ  ik - (4.13) . 122 INTRODUCTION TO RADAR SYSTEMS  where i = 1, 2, ... , N represents the ith tap, and k is an index from Oto N -1. 
 10.1  10.2 Factors Affecting Choice of Pulse  Compression System  .............................................  10.3  10.3 Linear FM   ...............................................................  10.4  10.4 Nonlinear FM  .......................................................... 
 SENSING DISCRIMINATOR HAS AN INVERSE SLOPE FOR A CROSS 
 90.Taylor J W..Jr..andJ.Mattern: Receivers. chap.5ofRadIII'Hc.mdhook. M.I.Skolnik(cd.), McGraw-Hili BookCompany, NewYork.1970. 
 A ground-based radar that operates without benefit of a radome must be  designed to withstand wind loads. 109 i 13 Surveillance radars must not only be able to operate  in strong winds, but must rotate uniformly. Rotating antennas outside or radomes cannot be  operated at winds that are too great. 
  WITH ##)2  
 Range-Measuring Systems. Radar's ability to separate returns from different ranges can be used advantageously along with directive antenna beams to simplify the scattering measurements. Most ranging scatterometers use either pulse modulation or FM, although more exotic modulations could also be used. 
 III. Given the dif ﬁculty of measuring performance in trials and uncertainty over the actual radar parameter values, the modelled results appear to be quite representative ofperformance reported in trials. The results in ﬁgures 7.5and7.6also illustrate the impact of sea conditions on target detection. 
 A 64-element network, for example, requires 192 directional couplers and 160 fixed­ phase shifters. The construction of a large Butler network requires a large number of  cross-over connections in the transmission lines. These can present practical difficulties in the  fabrication of the microwave printed circuits used to make up the device. 
 SION TO THE DOPPLER OFFSET OF EACH DOPPLER FILTER (OWEVER  THIS INCREASES THE TOTAL AMOUNT OF SIGNAL PROCESSING REQUIRED 4HE ENVELOPE AT THE OUTPUT OF THE &&4 IS FORMED WITH A LINEAR  )1   OR SQUARE 
 October.  1975.  129. 
 The gate acts  like a fast-acting on-off switch that turns the receiver “on” at the leading edge of the  target echo pulse and “off” at the end of the target echo pulse to eliminate undesired  echoes. The range-tracking system performs the task of keeping the gate centered on  the target echo, as described in Section 9.5. The primary output of tracking radar is the target location determined from the  pointing angles of the beam and position of its range-tracking gates. 
 _The design or a laser radar follows the same general principles as  other radars. hut with some exceptions.85·93·94·105  In addition to using a transmitter unlike those found at microwave frequencies, the laser  radar ex Iii bits other differences that must be accounted for when considering radar design. For  example. 
 o 
  D"(Z  K(Z 02& WAVEFORM 4HERMAL .OISE $ENSITY &LOOR AT !$   D"C(Z 0HASE .OISE TO 4HERMAL .OISE 2ATIO 
 Values of the constants are in Table 12.2. Figure 12.25 shows the clut- ter model for the midrange of angles as a function of frequency. The figure is only for vertical polarization because results are so similar for vertical and horizontal. 
 One is the transistor amplifier and the ottler is the  single-port microwave diode that can operate as either an oscillator or as a negative-resistance  amplifier. The silicon bipolar transistor has, in the past, been of interest at the lower rnicro-  wave frequencies (L band or below), and the diodes have been of interest at the higher micro-  wave frequencies. Gallium arsenide field-effect transistors (GaAs FET) have alsq been  considered at the higher microwave frequencies. 
 NENTS UP TO THE SIXTH ORDER IS SHOWN IN &IGURE  4HIS CHART ALLOWS IDENTIFICATION OF THOSE COMBINATIONS OF INPUT FREQUENCIES AND BANDWIDTHS THAT ARE FREE OF STRONG LOW 
 BASED INTERFEROMETRIC 3!2 CAPABILITY )N3!2  $ATA WERE COLLECTED OVER A VERY LARGE FRACTION OF THE GLOBAL LANDMASS +OSMOS  !LTHOUGH NOT CLASSIFIED IN THE STRICT SENSE  +OSMOS CAME TO VIEW LARGELY  AFTER THE LAUNCH OF ITS TECHNICAL  SUCCESSOR  !LMAZ 2USSIAN AND  !RABIC FOR  DIAMOND IN  THE ROUGH  0RECEDING THESE 3OVIET 3!2S WERE A SERIES OF REAL 
 HAND SIDE OF THE  3 PLANE TRANSFORMED TO THE INSIDE OF THE UNIT  CIRCLE CENTERED AT  :    :ERO FREQUENCY IS AT  :      J 4HE STABILITY REQUIREMENT IS THAT  THE POLES OF THE : TRANSFER FUNCTION LIE WITHIN THE UNIT CIRCLE :EROS MAY BE ANYWHERE &)'52%    .TH ORDER &)2 -4) CANCELER BLOCK DIAGRAM          &)'52%  /NE 
 AES-9, pp. 714-724, September, 1973.  20. 
 SENSING PORTION OF THE ANTENNA PATTERNS  AND THE RADAR RESPONSE IS STRONGLY DEPENDENT UPON THE SPECIFIC FEED DESIGN AND ERROR 
 Filter sidelobes not  shown. MT! AND PULSE DOPPLER RADAR 123  ing to the k =Oto N -1 weighting as given by Eq. (4.13). 
 ITY OF RADARS AT THESE FREQUENCIES -ILLIMETER 7AVE 2ADAR  !LTHOUGH THIS FREQUENCY REGION IS OF LARGE EXTENT   MOST OF THE INTEREST IN MILLIMETER WAVE RADAR HAS BEEN IN THE VICINITY OF  '(Z WHERE THERE IS A MINIMUM CALLED A  WINDOW  IN THE ATMOSPHERIC ATTENUATION    ! WINDOW IS A REGION OF LOW ATTENUATION RELATIVE TO ADJACENT F REQUENCIES 4HE WIN 
 7.17. The  traiist~iissioti lines from tile feeds are arranged to terminate on the periphery of a circle. A feed  liorti is rotated witliin tliis circle, transferring power from the tratismitter to each feed or group  of feeds it1 turn. 
 J., T. Moreno, and W. J. 
 This is a series-line, or a cascaded,  configuration. Although the discrete nature of the digitally switched phase shifter means that  the exact value of required phase shift cannot be achieved without a quantization error, the  error can be made as small as desired. (Even analog phase shifters, which are continuously  variable. 
 GAIN ANTENNA FOR DATA DOWNLINK AS  WELL AS FOR THE 3!2 $URING THE HIGH 
 A wider servo bandwidth is needed at close range to keep tracking lag within reasonable  values, but it must not be wider than necessary or the target angle scintillation errors,  which increase inversely proportional to target range, may become excessive. The low-pass closed-loop characteristic of a servosystem is unity at zero frequency,  typically remaining near this value up to a frequency near the low-pass cutoff, where  it may peak up to higher gain, as shown in Figure 9.15 a. The peaking is an indication  of system instability but is allowed to be as high as tolerable, typically to about 3 dB  above unity gain to obtain maximum bandwidth for a given servomotor drive system. 
 TEM  AND THEREFORE  FOR EACH CLUTTER AREA THAT EXCEEDS THE SYSTEM THRESHOLD BY  D" OR MORE  THE RESIDUE WILL EXCEED THE DETECTION THRESHOLD )F THE CLUTTER EXCEEDS THE THRESHOLD BY  D"  THE RESIDUE FROM THE -4) SYSTEM WILL EXCEED THE DETECTION THRESHOLD BY  D"  ELIMINATING THE EFFECTIVENESS OF THE -4) &IGURE  B SHOWS A  SKETCH OF THIS EFFECT 4O ENSURE THAT THE NOISE 
 The output waveform extends a distance T to either side of the peak  response, or central spike. The portions of the output waveform other than the spike are called  time sitlelobes.  The binary choice of O or n phase for each subpulse may be made at random. 
 In [ 38], authors proposed a novel ship classiﬁcation model combining kernel extreme learning machine and dragonﬂy algorithm in binary space. The result was shown in Table 9. Because of the dataset and the model, the result may not be exactly correct. 
 Second, thefunction ofthe attenuated square-wave voltage in- troduced after Point 1istobalance‘+ru- nnI-1 FIG.5.17.—Curve ashows thevoltage atPoint 1(cf.Fig.5,15) duetoastationary target andbshows thatduetoamoving target; thedotted envelope curve corre- sponds tothedoppler frequency. Curve cistheresult ofpassing bthrough afull- wave rectifier, and distheresult of filtering c. out the square-wave voltage due tothe d-ccomponent ofreceiver noise, asmodulated bythe gating. 
 BISTATIC  EQUIVALENCE THEOREM APPLIES IN THE PSEUDO 
 In the  AN/MPS-36 transmitter chain tlie SFD-257 is preceded by an SFD-244 cathode-pulsed CFA  witli I1 dl3 gain, wliicli is driver1 by a 904T1 catliode-pulsed TWT with 49 dB gain. TIie drive  power to tlie TWT is 50 rnW.  ~l'lie early radars dcveloi,cd duririg tlie 1930s used conventional grid-controlled vacuum tubes  si~icc rl~crc cxistctl rio otlic~. 
 When variable pulse spacing, very high pulse repetition rates (greater than 4000 pps), or‘‘coded pulses” (groups ofclosely spaced pulses) are required, thehard-tube pulser isalmost exclusively used. Although the line-type circuit can beadapted tosuch anapplication,l the advantages offlexibility yinherent inthe hard-tube pulser have restricted the use of theline-type pulser tovery special cases. Such acase occurs ifthesupply voltage issolow that therequired power output cannot beobtained from ahard tube. 
   TESTING PROBLEM IN WHICH  (  DENOTES THE HYPOTHESIS THAT NO TARGET IS PRESENT AND  (  IS THE HYPOTHESIS THAT THE TARGET IS PRESENT 7HILE SEVERAL CRITERIA IE  DEFINITIONS OF OPTIMALITY  CAN BE USED TO SOLVE THIS PROBLEM  THE MOST APPROPRIATE FOR RADAR IS THE .EYMAN 
 The fact that it zs  minute need not worry a radar receiver, for, as we have  seen in the introductory chapters of this book, the CRT  . ELECTRONIC NAVIGATION 147 -  and its associated circuits provide a very useful electronic  stop-watch, capable of indicating millionths of a second.  Now with our two radar transmitters we could plot a  very large number of positions where there are time  differences, and sets of lines could be drawn, fotning all  the points having the same time differences, with respect  to these two transmitters. 
 G.: The Dynamics of the Convective Process in Clear Air as Seen by Radar, J. Atm. Sci.,  vol. 
 SHAPING OF WAVEFORM REQUIREMENTS DICTATES LINEAR OPERATION OF AMPLIFIERS !PART FROM THE REQUIREMENT TO MEET EMISSION GUIDELINES LAID DOWN BY NATIONAL  AND INTERNATIONAL SPECTRUM MANAGEMENT AUTHORITIES  HIGH SPECTRAL PURITY IS ESSENTIAL BECAUSE SKYWAVE RADAR USES DOPPLER PROCESSING TO SEPARATE THE TARGETS FROM THE CLUT 
 VIA in a Wellington XIV 4-17 4.6 ASV Mk. VIC on Sunderland aircraft, ARI 5634 4-20Airborne Maritime Surveillance Radar, Volume 1 viii. 4.7 ASV Mk. 
 Cryo­ genic parametric amplifiers and masers produce the lowest noise figures, but the added  complexity of operating at low temperatures has tempered their use in radar.  The noise figure of the ordinary "broadband" mixer whose image frequency is ter­ minated in a matched load is not shown in Fig. 9.4. 
 This chapter will be devoted to arrays of this type. The capability of rapidly and accurately switching beams permits multiple ra- dar functions to be performed, interlaced in time or even simultaneously. An electronically steered array radar may track a great multiplicity of targets, illu- minate a number of targets with RF energy and guide missiles toward them, per- form complete hemispherical search with automatic target selection, and hand over to tracking. 
 III 1 Wellington squadron;ASV Mk. IIIB Nos. 58 and 502 Halifax MR squadrons; ASV Mk. 
 W.: Explorations in Fixed and Adaptive Resoliltion at GE and S[JRC, IEEE 7'rrrr1s.  vol. AP-24. 
 106.Oh,L.L.,C.D.Lunden, andC.Chiou:Fenestrated MetalRadome, Microwal'l! J.,vol.7,pro6265, April,1964. 107.Oh,L.L.,andC.D.Lunden: ASlotted Radome CapforRain,Hail,andLightning Proteclion, Microwave J.,vol.II,pp.105-108, March, 1968. 10KPelton,E.L.,andB.A.Munk:AStreamlined Metallic Radome,l EEETrans.,vol.AP-22,pp.799-lW3, November, 1974. 
 TRACING METHOD THAT ASSIGNS AN  AMPLITUDE AND PHASE TO FIELDS DIFFRACTED AT SMOOTH SHADOW BOUNDARIES AND AT SURFACE DISCONTINUITIES "ECAUSE THE LATTER ARE MUCH MORE SIGNIFICANT IN BACKSCATTERING COM 
 OFF SCHEDULING OF THE RADARS OPERATION  TO INCLUDE  ONLY THOSE TIME INTERVALS WHEN SURVEILLANCE IS REQUIRED  CAN REDUCE THE PROBABILITY OF THE RADAR LOCATION BEING FOUND BY DIRECTION FINDING $&  EQUIPMENT OR RADAR HOMING AND WARNING RECEIVERS 2ADAR BLINKING  USING MULTIPLE RADARS WITH COORDINATED ON 
 Radar System Engineeri ng Chapter 8 – Pulse Radar  53     After combining one obtains:   € Udiff=Ud=Ad⋅sin2πfdt−4πf0R c         (8.6)   By demonstrating a video signal at the indicator it is possible to distinguish two cases:   € fd>1τ fd<1τ (8.7)  From which the illustrations according to Figure 8.6 result.   at bt c t  Figure 8.6  a) Transmitting si gnal b) Video signal f d > 1/τ, c) Video signal f d < 1/τ.  The pulsing is identical to a sample of the Doppler oscillation. 
 34.-. Maximum scattering cross section oftriangular corner reflector. sequent reduction insignal return. 
 RETURN PROCEDURES WILL BE LIMITED BY THE PULSE SPACING  AND WILL APPROACH  SQ Q}  $    &)'52%  "LOCK DIAGRAMS OF VARIOUS DETECTORS 4HE LETTER  # INDICATES   A COMPARISON  S IS A DELAY  AND LOOPS INDICATE FEEDBACK FROM ' 6 4RUNK . Ç°È  2!$!2 (!.$"//+  WHERE $P IS THE ANGULAR ROTATION BETWEEN TRANSMITTED PULSES #ONSEQUENTLY  IF THE NUM 
 Fung37) FIGURE   16. 32 Measured scattering coefficient s ° (left scale) as a function  of soil moisture content for three surface roughnesses. The solid curve is the  reflectivity Γ (right scale) calculated on the basis of dielectric measurements. 
 35, pp. 68–78, 1997. 63. 
 46 to 9.47 sources of, 9. 26 target caused, 9.26 to 9.37 ERS SAR, 18.8 to 18.9 Evaporation ducts, 26. 11 to 26.12 Exponential model of land clutter, 2.12 to 2.16 Extended Interaction Klystron (EIK), 10.11 External noise at HF, 20.43 to 20.45 F F-117 low cross section aircraft, 14.40 to 14.42 F region, 20.14 to 20.15 Fading, 16.12 False-alarm control, 7.11 to 7.19 Far field, 14.4 Far-field criterion, 14.27 to 14.28 Fast Fourier transform (FFT), 25.33 to 25.34 filter bank, 2.55 to 2.56 Fast Time Constant (FTC), in CMR, 22.5 Fast-wave tube,  10.3 Ferrite phase shifters, 13.52 to 13.53 Fighter aircraft missions, 5.10 to 5.16. 
 (From Ridenour,28 courtesy McGraw-Hill Book Company, Inc.}  account of aspect changes and shadowing of one component by another) is computed and the  component cross sections are combined to yield the composite value. The" theoretical" values  of Fig. 2.17 for B-47 were obtained by calculation. 
 Typically, the receiver is designed  to provide controlled gain compression through a limiting stage at the final IF as  described in Section 6.8. Analog-to-Digital Converter Full Scale.  The A/D converter full scale level deter - mines the maximum level that can be digitized. 
 2.8b, L1(40) is 3.5 dB and L1(10) is 1.7 dB, so that  the collapsing loss is 1.8 <l B. It is also possible to account for the collapsing loss by substituting  into the radar equation of Eq. (2.33) the parameter E1(m + n) for E1(n), since E1(n) = 1/Li(n). 
 As M increases, the peak-sidelobe–voltage ratio approaches ( p M)−1. This cor - responds to approximately a 10-dB improvement over pseudorandom sequences  of similar length. The ambiguity function grossly resembles the knife-edge (ridge)  characteristic associated with LFM waveforms, as contrasted with the thumbtack  characteristic of pseudorandom sequences (Figure 8.20) However, for small ratios of  doppler shift to waveform bandwidth, a good doppler response can be obtained for  reasonable target velocities. 
 745-753, June, 1974.  99. Tolbert, C. 
 When the snow is dry, scatter comes from a large volume; when it is  wet, the scattering volume is much less because of higher attenuation. As a result,  FIGURE   16. 37 Time variation of scatter from ( a) corn and ( b) alfalfa at incidence angles of vertical  and 50° ( after E. 
 rrewverRcmoe ‘-~“Amplifier = ‘LJClactronic PPI Waveforms (a)TriggerJllllll———————.—+1111111 (b)fime~se(~)w-----––---u ~@. + ‘z (c)Rein e ‘3 K,Rwac (~RC099~ ma FIG.12.3.—Electronic PPI and RHI. inFig. 
 One method of obtaining tracks with a surveillance radar is to have an operator manually  mark with gr~ase pencil on the face of the cathode-ray tube the location of the target on each  scan. The simplicity of such a procedure is offset by the poor accuracy of the track. The  accuracy of track can be improved by using a computer to determine the trajectory from  inputs supplied by an operator. 
 INCH SHELLS WERE EXPENDED 'UN FLASHES WERE REPORTEDLY SEEN BY THE *APANESE ON +ISKA   MILES AWAY 4WO OTHER SHIPS  THE DESTROYERS 533 3AN &RANCISCO  AND 533 3ANTA &E  COULD NOT GAIN RADAR CON 
 4. Aplot ofEq. (6)using theequality sign isgiven inFig. 
 DENT CIRCULAR POLARIZATION (OWEVER  VERY FEW SHIPBORNE NAVIGATIONAL RADARS USE #0  EVEN THOUGH n D" IMPROVEMENT IN RAIN CLUTTER REJECTION IS TYPICALLY ACHIEVED FROM ITS APPLICATION 4WO IMPORTANT FACTORS HAVE CONTRIBUTED TO THIS &IRST  IT MAKES THE ANTENNA MORE EXPENSIVE  EXACERBATED BY )-/S REQUIREMENTS THAT  '(Z RADARS MUST BE AT LEAST SWITCHABLE TO HORIZONTAL POLARIZATION WHEN SEARCHING FOR SURVIVAL CRAFT FITTED WITH 3EARCH AND 2ESCUE 4RANSPONDERS SEE 3ECTION   3ECOND  BY USE OF  SMALL RANGE CELLS AND BY IMPLEMENTING CONVENTIONAL SIGNAL DIFFERENTIATION TECHNIQUES   MODERN RADARS  PARTICULARLY AT  '(Z  GIVE REASONABLE PERFORMANCE IN MOST COMMONLY EXPERIENCED PRECIPITATION CLUTTER  4HEREFORE  USERS AND MARITIM E AUTHORITIES ARE GENER 
 G. II.: Choosing the Number of Faces of a_ Phased-Array Antenna for Hemisphere Scan  Coverate. IEEE Trans .. 
 98. W. H. 
 OGRAPHERS DESCRIPTOR OF THE SEA SURFACE HAS HAD A POWERFUL INFLUENCE ON THINKING ABOUT THE PHYSICAL ORIGINS OF SEA CLUTTER )T IS APPEALING IN ITS SIMPLICITY  AND IT SUGGESTS A DIRECT WAY BOTH TO PREDICT RADAR CLUTTER FROM MEASUREMENTS OR FORECASTS OF THE SEA SPEC 
 RADAR CLUTIER 503  of the diameter, Eq. ( 13.17). Since the diameter of cloud droplets is about one-hundredth the  diameter of raindrops, the echoes from fair-weather clouds are usually of little concern. 
 Anexample comparing theresolution oftheconventional antennaandthetwotypesof synthetic aperture antennas isshowninFig.14.3. l'wasmentioned thattI,efactorof2inthedenominator ofEq.(14.4)wasaconsequence oftherelativephaseshiftbetween elements ofthesynthetic arrayantenna beingduetothe two-way propagation path,insteadoftheone-way propagation pathasintheconventional arrayantenna. Thisresultsinthesynthetic aperture radarhavingatwo-way antennapattern E FllUre14.3Comparison oftheresolution ofa .'---- ----,,-'::1- --,-JI,-:-synthetic aperture radarandaradarwithacon- II 10 100ventional antenna, assuming anX-bandantenna Range.km withdimension D=3m.. 
 R. J. Doviak, R. 
 This is in contrast with azimuth directivity  for transmitting, where an increase in directive gain is accompanied by a decrease in  area coverage. For noise-limited detection, this can be compensated by a reduction in  dwell time, but for clutter-limited detection there may be a penalty for coverage rate.  Some radars use horizontal two-dimensional arrays with up to ~ 100 receive channels  to achieve quite high vertical directivity on both transmit and receive. 
 The reflected pulse, ofopposite polarity, turns offthe flopover. The resulting square. 708 RADAR ltELAY [SEC.1743 wave from the flopover isused toopen the sine pulse switch for25~sec orsoattheexpected time ofarrival ofthe sine pulse. 
 &IELD  -ETHOD  OF  !NALYSIS  4HE APERTURE 
 < i. J . .I. 
 Thisdoesnothappenwhentracking inrectilinear coordinates. Therectilinear coordinates oftheupdated targetprediction areconverted backto radarcoordinates todrivetheantenna. Systematic errorsaredetermined bypriormeasurement andareusedtoadjustthe encoded antenna position toprovidethecorrecttargetposition. 
 pp. 23-26. October, 197J. 
 Since phase shift is periodic with period 2rr, it is possible in many  applications to use a phase shifter with a maximum of 2rr radians. However, if the pulse width  is short compared with the antenna response time (if the signal bandwidth is large compared  with the antenna bandwidth), the system response may be degraded. For example, if the energy  (a)  ( b) Figure 8.4 Series arrangements for  applying phase relationships in an  array. 
 3HIFTER 1UANTIZATION ,OBES  0EAK QUANTIZATION SIDELOBE VALUES ARE DERIVED  BY -ILLER CONSIDERING THE ACTUAL APERTURE PHASE DISTRIBUTION &IGURE  SHOWS THIS  DISTRIBUTION FOR SOME SCAN ANGLE  P AND THE RESULTING ERRORS DUE TO PHASE QUANTIZATION  !LTHOUGH A CONTINUOUS CURVE HAS BEEN DRAWN  ONLY POINTS CORRESPONDING TO INTEGRAL  VALUES OF - ARE MEANINGFUL 4HE GREATEST PHASE 
  
 FREE FREQUENCY BANDS  APPROXIMATELY  OF THE INTERMEDIATE FRE 
 The geometric relationship is shown in Figure 2. The necessary parameters are given in Table 1. T able 1. 
 The RCS Matrix of the sphere  has the form:  € Ssphere[ ]=Ssphere (f)⋅10 01         (11.18)  The time domain representation in Figure 11.9 shows the Radar pulse response calculated  from the measurements for a sphere with a diameter of 3.6 cm and with 14 GHz bandwidth.  The backscattered wave results from a portion, which is directly reflected on the forefront of  the sphere (optical portion) – first maximum of the impulse response – as well as from a po r- tion, which “creeps” around the sphere (creeping wave).  The distance between both maxima  is calculated to twice the radius of the sphere plus half of the circumfere nce. 
 It is not strictly necessary to use   ch02.indd   78 12/20/07   1:46:35 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 The intensive solar radiation results in the ionization of ionospheric molecule. Varying from the scale of spatial distribution, the ionosphere is typically categorized into the background ionosphere Sensors 2019 ,19, 2161; doi:10.3390/s19092161 www.mdpi.com/journal/sensors 183. Sensors 2019 ,19, 2161 (larger than 10 km) and ionospheric irregularities (less than 10 km) [ 8,14]. 
 # DATA QUALITY AND CALIBRATION RESULTS v  )%%% 4RANSACTIONS ON 'EOSCIENCE   AND 2EMOTE 3ENSING  VOL   PP n     " 2ABUS  - %INEDER  ! 2OTH  AND 2 "AMLER  h4HE SHUTTLE TOPOGRAPHY MISSIONA NEW CLASS OF  DIGITAL ELEVATION MODELS ACQUIRED BY SPACEBORNE RADAR v  0HOTOGRAMMETRY AND 2EMOTE 3ENSING   VOL   PP n    7 9IRONG  : -INHUI  AND ( 7EN  h3!2 ACTIVITIES IN 02 #HINA v IN  0ROCEEDINGS  TH %UROPEAN  #ONFERENCE ON 3YNTHETIC !PERTURE 2ADAR  $RESDEN  'ERMANY  6$% 6ERLAG    9 3HARAY AND 5 .AFTALY  h4%#3!2 DESIGN CONSIDERATIONS AND PROGRAMME STATUS v  )%% 0ROC  2ADAR 3ONAR .AVIGATION  VOL   PP n    % 0 7 !TTEMA  h4HE ACTIVE MICROWAVE INSTRUMENT ON 
 When the axis of rotation is held stationary. the Palmer scan reduces to the conical . 178 INTRODUCTION TO RADAR SYSTEMS  (a) ( b)  (d) ( C)  ( e) Figure S. 
 AXIS POSITION   ! SOLUTION USED WITH MISSILE 
 However,detection of submarines may often have been clutter-limited, when the increased transmitter power would have had no appreciable effect. In November 1944, CCDU conducted trials to compare ASV Mk. III and VI [ 9]. 
 END OF THE BAND  EXTRATERRESTRIAL OR GALACTIC NOISE MAY BE GREATER THAN THAT DUE TO SFERICS 2ECEIVE SITES IN AN AREA OF EXTENSIVE ELECTRICAL EQUIPMENT USE CAN FIND ANTHROPOGENIC NOISE DOMINANT "UT MOST IMPORTANTLY  THE (& BAND IS DENSELY OCCUPIED BY OTHER USERS  ESPECIALLY POWERFUL (& BROADCASTERS RELYING ON THE PREVAILING FRE 
 S)'stemconsiderations. Thcpotcntial advantages claimedforsolid-state sourcesinradarmay besummarized as(1)long,failure-free life,(2)lowtransmitter voltage,whicheliminates the riskofX-raysandelectricshock.(3)amplitude controlofthetransmitted waveform byselec­ tivelyswitching modules orindividual dcvicesonoroff,(4)widebandwidth, (5)lowprojected volume-production costs,and(6)aircooling.Therearesomeproblems, however, intheuseof solid-statc dcvicesforradarsystemsotherthancost.. 220 INTRODLJCTION TO RADAR SYSTEMS  As mentioned, the solid-state transmitter has some significant differences as compared to  the conventional tube transmitter. 
 Long pulses can be a disadvantage in military radars since they reduce the  effectiveness of pulse-to-pulse frequency agility. A jammer can determine the radar frequency  at the beginning of the long pulse and quickly tune a jammer to the correct frequency within  the duration of the pulse. To achieve improved range-resolution with the long pulse, pulse  compression is needed. 
 61, pp. 1 167 1 168, Augifst, 1973.  12 1 Ariticrsoli, I.: Mcnsurernctits of 2O-C;Ilz Tra~is~iiissiori Tliroi~gli a Radof~ic in Rain, IEEE Trc~rrs.,  vol. 
 Space-based  ch18.indd   20 12/19/07   5:14:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 TRACK GRADIENT OF THE OCEANIC GEOID 4HE 40 INSTRUMENT PACK 
 3.3 ASV Mk. III description ASV Mk. III was essentially the same as H 2S Mk. 
 A  TACCAR, for example, might be designed to reject ground clutter close in, and weather or  chaff at a different doppler at ranges beyond the ground clutter; but not to cancel two different  clutter doppler frequencies simultaneously.' An exception is the adaptive MT162.65 which can  adapt to any type of clutter. Using technology similar to that of the antenna sidelobe canceler,  nulls are adaptively placed at those frequencies containing large clutter. A three-loop adaptive  canceler, for example, can adaptively place three nulls at three different frequencies or it can  place the three nulls so as to make a single wide notch, depending on the nature of the clutter  spectrum. 
 E '" \.... Ii)'\\ua10a.\\ '"L ..9-\Minimum '"'" \\ '"c....\\Cosmicnoisefrom.cCosmicnoise 0' Lfromgoloctic \ \ galacticcenterco pole \\ 1 100 ',000 10,000 100,000 Frequency, MHz Figure12.11Maximum andminimum brightness temperatures oftheskyasseenbyanidealsingle­ polarization antenna onearth.(AfterGreeneandLebenbaum,so Microwave J.) attenuated inpassingthroughtheatmosphere. Thenoisepoweravailable overabandwidth Bn fromtheimaginary blackbody iskJ:aBII"Thenoisepowerafterpassingthrough theatmos­ phereiskJ:aB,jL.Thustheamountofpowerabsorbed bytheatmosphere iskTjIBII(1-1/L) andisequaltothenoisepower ~Nradiated bytheatmosphere itself.Fromthedefinition of effective noisetemperature andthefactthatt/Listhe"gain"(lessthanunity),thefollowing equation isobtained: Hence!!N=kT.BG=kTeB"=kTB(1-!)ell, L anL Te=TlI(L-1) (12.15) Iftheatmospheric losswere1dBatatemperature of260K,theeffective noisetempera­ turewouldbe68K;a3-dBlossresultsinTe=260K,whileato-dBlossgivesTe=1340K. 
                     %    %            !"#!!$        &)'52%   !PPARENT LOCATION OF A DUAL 
 WAVE ATTENUATION  /N THE BASIS OF 2YDES WORK  3AXTON AND (OPKINS GIVE THE FIGURES IN 4ABLE   FOR THE ATTENUATION IN A FOG OR CLOUDS AT  n# TEMPERATURE 4HE ATTENUATION VARIES WITH  THE TEMPERATURE BECAUSE THE DIELECTRIC CONSTANT OF WATER VARIES WITH TEMPERATURE THEREFORE  AT n# AND n# THE FIGURES IN 4ABLE  SHOULD BE MULTIPLIED BY  AND    RESPECTIVELY )T IS IMMEDIATELY NOTED THAT CLOUD OR FOG ATTENUATION IS AN ORDER OF MAGNITUDE GREATER AT  CM THAN AT  CM AND THAT NEARLY ANOTHER ORDER OF MAGNITUDE INCREASE OCCURS BETWEEN  AND  CM 2ANGE AND 6ELOCITY !MBIGUITIES  7EATHER RADARS UTILIZE A SEQUENCE OF PULSES  TO MEASURE THE RADAR REFLECTIVITY AND DOPPLER CHARACTERISTICS "ECAUSE THE PULSING RATE TYPICALLY DETERMINES THE SAMPLING FREQUENCY FOR DOPPLER QUANTITIES ON A CONSTANT PULS 
 Some references that appeared in the first edition  have been omitted since they have been replaced by more current references or appear in  publications that are increasingly difficult to find. The references included in the first edition  represented a large fraction of those available at the time. It woilld have been difficult to add to  them extensively or to include many additional topics. 
 That is, there is a particular elliptical polarization which produces the  hest cancellation. The optimum elliptical polarization depends on the nature of the rain. This  effect is due to the nonspherical raindrops which cause the phase shirt and attenuation of the  radar energy to be different depending on the direction of polarization. 
 P.: Microwave Propagation over Rough Surfaces, RCA Rev., vol. 20, pp. 308-335,  June, 1959. 
 16.90 the first pulse is transmit- ted and received on the forward antenna A1. The second pulse is transmitted and received on the rear antenna A2 during the next interpulse period. If d = VgTp, then the antenna used on the first pulse, A1, will coincide with the antenna A2 used on the second pulse. 
 I. Shustov, V . A. 
 SIGNAL RATIOS ARE TYPICAL OF (& RADAR SOME FORM OF DOPPLER FILTERING IS USED TO SEPARATE TARGETS FROM CLUTTER )N &IGURES       AND   PERFORMANCE ESTIMATION CURVES ARE GIVEN  FOR WINTER AND SUMMER SEASONS  NIGHT AND DAY  AND LOW SOLAR ACTIVITY 4HE PERMIS 
 1 Record  of the meeting and demonstrations , His Majesty’s Stationery Office, London, 1946. ch22.indd   35 12/17/07   3:02:41 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 .. 0 52  Wooded hills .L 1.7 3 -05 0 63  Forest X 1.4 0 17 0 7 051 053  Cult~vated land X 14 0 17 0 7-5 0 061 20  Sea state 1 X 0 5 0 02 3 7 1 45  Sea state 3 K , 5 0 1 I0300 116 178 --  496INTRODUCTION TORADAR SYSTEMS effectiveness ofinterclutter visibility hasbeenexploited inMTIradarandinnon-MTI radar withlog-FTC receiver characteristics. Asanexample oftheeffectsofhighresolution onlandclutter,measurements havebeen reported withahorizontally polarized C-bandradarhavinga15-nspulsewidth(3mresolu­ tion)anda1.5°beamwidth.43AruralregioninEngland consisting ofwoods,fields,buildings, villages, smalltowns,andstructures suchaspylons,wasexamined atrangesfrom7to11km. 
 There is a difference in the time taken to get a fix on  these systems. In Gee pulses from both pairs of stations  appear on the CRT at the same time, and readings are  taken simultaneously. In Loran only one set of readings  can be taken at a time. 
 The proposed framework performed comparable to PCAKM as a change detection algorithm. The San Francisco dataset doesn’t contain registration and perspective errors with speckle noise. Figure 8. 
 Geophys. Res. , vol. 
 The use of height as the third target-coordinate is more desirable than the elevation angle in  applications where the Iieight is apt to be constant. This is usually true for commercial aircraft  and for satellites wit11 nearly circular orbits. A radar whose purpose is the measurement of  elevation angle, and which usually does not measure the azimuth angle, is called a height-finder  radar. 
 Acoust ., vol. 8, pp. 252–257, 1963. 
 Ctrrric: N. C'.. I:. 
 YEAR MISSION  SUBSE 
 The transmitter noise  is reflected back from the clutter and enters the receiver and is sometimes called  “transmitted clutter.”40 Some types of microwave tubes are more of a problem than  others. Extraneous noise in a microwave amplifier tube at the frequencies expected  from doppler-shifted target echoes can be produced by ion oscillations. According  to A. 
 LOAD 6372  MOST NOTABLY FROM THE ANTENNA !LSO  ANCILLARY CIRCUITRY SUCH AS ENERGY STORAGE CAPACI 
 6.2 . This page has been reformatted by Knovel to provide easier navigation. Contents     xiii   6.2 Basic Principles and Parameters  ............................ 
 LS-CS-Residual mainly has three steps: initial LS estimate, CS on the residual and ﬁnal LS estimate. The LS estimate step can be used to reduce the bias. The missed detections are reduced because the support information is adopted in the process of the LS-CS-Residual. 
 }Iost oftheuseful signals in any radar setarestrong enough tobepractically unmistakable. MICROWAVE PROPAGATION Inthefirst part ofthis chapter theradar equation was derived under theassumption offree-space propagation. The assumption isfrequently notjustified, and wemust now turn tosome oftheimportant cases that failtofulfill one ormore oftherequirements laid down inSec. 
 It does not depend on energy radiated by the target itself.The ability to detect a target at great distances and to locate its position withhigh accuracy are two of the chief attributes of radar.There are two groups of radio frequencies allocated by international standardsforusebycivilmarineradarsystems.TheﬁrstgroupliesintheX-band which corresponds to a wavelength of 3 cm. and has a frequency rangebetween 9300 and 9500 MHz. The second group lies in the S-band with awavelength of 10 cm. 
   
 FILTER EQUIVALENT  OF THE 3 PLANE WITH THE LEFT 
 Inany practical design itisusually desirable tomake C,nobigger than absolutely neces- sary, the criterion being the permissible voltage drop while carrying acurrent pulse ofdefinite magnitude for the duration ofone pulse. Expressed more quantitatively, Co=Ito/AV_O. If1=10amp, to=1 psec, and thepermissible voltage drop AV~O =100volts, wefind that CO must be0.1pf. 
 135–142, March 1965. ch08.indd   43 12/21/07   10:22:44 AMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 R. Hollaway, A. M. 
 ton1Dr-C02~  I I I I I I I I 00 000000 --------;  Probability of  1 i\ false alarm --+-------i  10-6 10-10-a,o-10-1010-n ,0-12 /  8 10 12 14 16 18 20  ( S/N )1, signal-to-noise ratio, dB  Figure 2.7 Probability of detection for a sine wave in noise as a function of the signal-to-noise (power)  ratio and the probability of false alarm.  Both the false-alarm time and the detection probability are specified by the system require­ ments. The radar designer computes the probability of the false alarm and from Fig. 
 This value ofMincreases the cutoff frequency toavalue of1.73 times that ofthesimple RCcircuit, but produces a2.5 percent overshoot onthepulse (the same amount asthat produced bya transitionally coupled i-fstage). Still greater bandwidths can beobtained bytheuseofseries peaking’ oracombination ofseries and shunt peaking. These circuits aremore difficult touse, however, and thereader isreferred toVol. 
 END TRANSMIT AND RECEIVE  HARDWARE IS CONFIGURED  AND IN 
 MITTED BY !)3 4HIS INFORMATION IS NOT AVAILABLE FROM RADAR ONLY THE COURSE CAN BE DETERMINED   AND YET HEADING IS USED AS THE BASIS FOR DETERMINING COLLISION AVOIDANCE ACTION 4HE !)3 TRANSMITTED HEADING SHOULD ALIGN WITH THE TARGETS VISUAL ASPECT AND  THEREFORE  THE NAVIGATIONAL LIGHTS ON A VESSEL 6ESSEL NAMES CAN BE ADDED AUTOMATICALLY TO TARGET TRACKS ON THE RADAR!)3 DISPLAY  AND IF THERE IS A NEED TO COMMUNICATE ON 6(& WITH A PARTICULAR TARGET  THE RADIO CALL SIGN IS ALSO AVAILABLE FROM THE !)3 DATA 4HE DESTINATION PORT AND %4! CAN SOMETIMES BE USEFUL IN DETERMINING THE LIKELY INTENTIONS OF TARGETS  ALTHOUGH SUCH ASSUMPTIONS MUST BE TREATED WARILY ! SIGNIFICANT ADVANTAGE OF RADAR IS THAT IT DOES NOT NEED COOPERATIVE TARGETS )T  ATTEMPTS TO DETECT ALL OBJECTS OF POTENTIAL INTEREST )TS INHERENT 2ELATIVE -OTION MODE OF OPERATION MAKES IT IDEALLY SUITED FOR COLLISION AVOIDANCE USEPARTICULARLY AS IN THIS  MODE IT HAS NO REQUIREMENT TO NEED OWN SHIPS GEOGRAPHICAL POSITION (OWEVER  RADAR IS BASICALLY CONFINED TO LINE 
 Geometric dilution of precision  (GDOP ) establishes multistatic location accuracy  (and resolution) and is developed by D. Barton in Chapter 6 of Willis and Griffiths.2  GDOP is a function of the angle of intersection, a, between isorange contours. Because  the bisector of a bistatic angle is orthogonal to an isorange contour, GDOP can readily  be determined by the angle of intersection, also a, of these bistatic bisectors. 
 S. Barbarossa and A. Farina, “Space-time-frequency processing of synthetic aperture radar  signals,” IEEE Transactions on Aerospace and Electronic Systems , vol. 
 ORBIT INCLINATION (degrees) FIG. 22.8 STS (Shuttle) cargo weight versus inclination for various circular-orbit altitudes (de- livery only—no rendezvous). maneuvering-system (OMS) on-orbit velocity increments. 
 Although the gain isconsiderably less than 1,this isnot appreciably less than would beobtained with aplate- coupled amplifier working into such alow impedance. Following the line and bridged across itare the video amplifiers associated with each indicator. Since these amplifiers can belocated very near tothe control electrode ofthe CRT, stray capacities can be kept very small. 
 Radar System Engineering  Chapter 12 – Selected Radar Applications  150     € RFF−LKW=2⋅d2 λ=2km (13.3)  Since large objects no longer find themselves in the far field, the calculational reflection cross - section cannot be achieved.  The 76 GHz Radar with 1° half -power bandwidth and at a di s- tance of 100 m only illuminates a circle with a diameter of 1.73 m.  Figure 13.21 shows the  typical reflection cross -section σ for 76 GHz. 
 In WASAR, the subaperture images can be regarded as the video indexed on subaperture [ 2], which is a map of reﬂectivity as a function of viewing angle. The reﬂectivities of the targets can be described via their amplitudes and positions. Although they vary with aspect angle, the positions are highly overlapped. 
 For the gaussian clutter spectrum, the optimum improvement factor is shown in  Figure 2.27 as a function of the rms relative spectrum width, assuming zero mean for  the spectrum. Calculations are shown for MTI cancelers of order N = 2 through 32. For the polynomial clutter spectrum, the optimum improvement factor is shown in  Figure 2.28, again as a function of the RMS relative spectrum width assuming zero  mean for the spectrum. 
 9−14. 35. D. 
 Thus aloss insignal-to-noise ratio occurs when the signals arepassed through thevideo amplifier, whose bandpass character- istic iswrong fori-fsignals. Itisinteresting tonote that again insignal- to-noise ratio can beobtained theoretically bydetuning the coherent oscillator sufficiently and replacing ‘“’~the video amplifier byani-fampli- fier having asuitable pass band.’ However, since this scheme requires @)~-~o~n-~ much greater precision inthecancel- F1o. 1617.-Effect ofdetuning the lation circuits, itisprobably better to coherent oscillator. 
 APERTURE BEAMWIDTH P"   $PPyy"$L    4HUS   DL CRyy$P$    5NDER  IDEAL CONDITIONS  AS LONG AS  $  K AND SIGNAL 
 Whenever possible the magnetrons are identified bytheir RMA type numbers. The values ofpulse power given inthk chart areconservative ones corresponding toreliable operating conditions. Pulse powers consider- ably inexcess ofthose given forthe highest power tubes have been FIG. 
 TO 
 A disadvantage of the staggered prf is its inability to cancel second-time-around clutter  echoes. Such clutter does not appear at the same range from pulse to pulse and thus produces  uncanceled residue. Second-time-around clutter echoes can be removed by use of a constant  prf. 
 Hybridtracking system. Conopulse86and"scanwithcompensation,,8 7arethenamesgivento ahybridtracking systemthatisacombination ofmonopulse andconicalscan.Twosquinted beams,similartothoseofasingleangle-coordinate amplitude-comparison monopulse, are scanned (rotated ornutated) inspacearoundtheboresight axis.(Intheconicalscantracker, onlyonesquinted beamisscanned.) Inconopulse, thesumanddifference signalsreceived in thetwosquinted beamsareextracted inamannersimilartothatoftheconventional monopulse system.Two-coordinate angleinformation isobtained byscanning thebeamsaboutthebore­ sightaxissimilartotheextraction ofazimuth andelevation angleinformation intheconical­ scantracker. Amplitude fluctuations ofthetargetechosignaldonotinprinciple degrade the tracking accuracy asintheconical-scan trackerbecause adifference signalisextracted from thesimultaneous o'utputsofthetwosquinted beams.However, theneedtoscanthetwobeams meansthatasinglepulseangle-estimate isnotobtained asinatruemonopulse. 
 Also, ancillary circuitry such as energy storage capaci - tance for pulsed operation, built-in-test (BIT) sensors, or adaptive control components  may be included. Amplifier & Module Design.  Solid-state amplifiers for use in transmitter  design are often referenced by their class of operation. 
 One of the prominent places in which residue caused by unsynchronized local  oscillators has shown up is in pulse-compression sidelobes. If the pulse-compression  sidelobes from fixed clutter returns vary from pulse to pulse, they do not cancel. This  coherency issue has been further discussed by Taylor.51 Rule 4. 
 After the ﬂat phase removal and phase unwrapping operations, the interferometric phase image could be used for DEM inversion. The DEM image obtained by the interferometric phase inversion is the slant range image, as shown in Figure 20a. We utilized the proposed polar coordinate transformation method to transform it to the ground range. 
 The straps provide  stability since they connect all those segments of the anode which have the same potential in  the rr mode and thus permit the tube more readily to operate in this preferred mode.  Instead of tile hole and slot resonators of Fig. 6.1, vanes may be used, as in Fig. 
 11.2. FIG. 11.2 RCS of a perfectly conducting sphere as a function of its electrical size ka. 
 RESONANT WAVE COMPONENTS IN THE CLUT 
 71. Siebert, W. M.: Some Applications of Detection Theory to Radar, IRE Natl. 
 M..  rid P. A. 
 8.3PHASE SHIFTERS ThedilTerence inphase¢experienced byanelectromagnetic waveoffrequencyfpropagating withavelocity 1"through atransmission lineoflengthIis ¢=lrr/lll' (8.15) Thevelocity l'ofanelectromagnetic waveisafunction ofthepermeability )1andthedielectric constant (ofthemedium inwhichitpropagates. Therefore, achangeinphasecanbehadbya changeinthefrequency, .lengthofline,velocity ofpropagation, permeability, ordielectric constant. Theuseoffrequency toelTectachangeofphaseisarelatively simpletechnique for electronically scanning abeam.Itwasoneofthefirstpractical examples ofelectronic scanning andhasheenwidelyemployed. 
 {°n  2!$!2 (!.$"//+  OFFSET APPLIED TO THE TRANSMIT FREQUENCY 4HE MEDIUM 
 THE RADAR EQUATION 33  repeated for each value of)' and 11.13 This is not done here. Instead, for simplicity, an efficiency  will be defined which is the ratio of the average signal-to-noise ratio for the exponential  integrator to the average signal-to-noise ratio for the uniform integrator. For a dumped  integrator, one which erases the contents of the integrator after II pulses and starts over, the  efficiency is 1 4  tanh (11y/2) p=  11 tanh (1,/2) (2.35a)  An example of an integrator that dumps is an electrostatic storage tube that is erased whenever  it is read. 
 The clutter-free region is defined as that portion of the spectrum in which no ground clutter can exist. (A clutter-free region usually does not exist with medium PRFs.) The sidelobe clutter region, 4Vy\ in width, contains ground clutter power from the sidelobes of the antenna, although the clutter power may be below the noise level in part of the region. The main-beam region, located at /o + (2VyX) cos v|j0, contains the strong return from the main beam of the an- tenna striking the ground at a scan angle of i|;0, measured from the velocity vec- tor. 
 3,  pp. 252-253, June, 1967.  96. 
 F. W. and N. 
 )43 2ADAR 0ERFORMANCE  -ODEL DEVELOPED BY ,UCAS ET AL  PROVIDES A NUMBER OF TOOLS FOR RADAR PER 
 12–16. 116. E. 
 TO 
 V AND  V  WOULD NOT BE PRESENT AND THE  IMAGE  
 The receiver employs a bank of filters, each tuned to a different carrier frequency  which in turn corresponds to a different angle. This is analogous to the output of a beam-  fornling matrix, as in Sec. 8.7. 
 ‘—For metal targets whose dimensions aswell asradii ofcurvature arelarge compared with the radar wavelength, the following approximation yields good results. For every surface element thectirrent isused which would becaused by theincident field ifthe surface element were apart ofaninfinite plane sheet. The radiation from allthesurface elements isadded intheproper phase relations, and theresultant field isconsidered asthescattered field from the target. 
 Odoardi. F .. and C. 
 Schwartz M.: A Coincidence Procedure for Signal Detection, IRE Trans., vol. IT-2, pp. 135-139,  December, 1956. 
 WIND  AND THE UPWIND ASPECT USUALLY IS A BIT STRONGER THAN DOWNWIND 7IND VECTOR DATA HAVE BEEN COLLECTED BY AIRBORNE SCATTEROMETERS FLYING IN CIRCLES LITERALLY  OVER INSTRUMENTED TEST SITES   4HERE HAVE BEEN MANY ATTEMPTS OVER THE YEARS TO CONVERGE ON A SUITABLE MATHEMATI 
 PHASE )  AND QUADRATURE 1  SIGNED NUMBER PAIRS  AT EACH PIXEL 3,# DATA ARE REQUIRED FOR 3!2 INTERFEROMETRY  POLARIMETRY  AND COHERENT CHANGE DETECTION 0USHING !MBIGUITY ,IMITS   4HE BASELINE SINGLE 
 12. Sensors 2019 ,19, 1701 3.2. Improved RMA Algorithm RMA [ 15–21] achieves SAR imaging in the wave number domain. 
 The effects of undesired background sig - nals are illustrated in Figure 14.21. Because  the relative phase between the background  signal and the target signal is unknown, two  curves are shown; they correspond to perfect  in-phase and out-of-phase conditions. If the  background signal is equal to the target signal  (ratio of 0 dB) and the two are in phase, the  total received power is four times the power  due to either one. 
 Improving SAR-Based Urban Change Detection by Combining MAP-MRF Classiﬁer and Nonlocal Means Similarity Weights. IEEE J. Sel. 
 Chapter 10 deals with pulse compression, and only brief mention of its ability to aid in the discrimination process will be included here. Physically, decoding such echoes may occur as part of the intermediate-frequency (IF) filter, typically with surface acoustic-wave (SAW) devices or with digital correlators, either pre- ceding or following doppler filtering. In Fig. 
 ‘Quarter-wave plates andhalf-wave plates forradar, entirely analogous tothose familiar inoptics, canbemade. l~hat isnecessary istomake thephase velocity ofthe\va\,e asitpasses through theplate depend upon itsdirection ofpolarization with respect tosome direction intheface oftheplate. This isdone bymaking the plate ofastack ofparallel metal sheets spaced anappropriate distance from one another. 
 2.8 is the false-alarm ,wmber, as introduced by  Marcum.10 It is equal to the reciprocal of the false-alarm probability Pr,. defined previously by  Eqs. (2.24) and (2.25). 
 Theintrinsic regionactsasaslightlylossy dielectric atmicrowave frequencies andtheheavilydopedregions aregoodconductors. Whenbiasedinthereverse(nonconducting) state,thePINdioderesembles alow-loss capaci­ tor.Itisessentially aninsulator situated between twoconductors andexhibits theparallel­ platecapacitance determined bythedielectric oftheintrinsic region.Atmicrowaves, the small-signal equivalent circuitofthePINdiodemayberepresented asaseriesRCcircuitwith thecapacitance determined bythearea,thickness, anddielectric constant oftheintrinsic region.Thecapacitance isindependent ofthereverse-bias voltage. Theseriesresistance is determined bytheresistivity andgeometry ofthemetallic-like PandNregions. 
 Ofcourse NM isclosely related. tothe more general and more loosely defined quantity niintro- duced inSec. 2.11. 
 ELEMENT FEED  A CONFLICT GENERALLY  ARISES BETWEEN THE GOALS OF HIGH SUM 
 Or we could keep a steady small negative charge here  to throttle down the beam, but link the grid circuit to  the signal circuits so that a momentary voltage which is  caused to deflect the beam also, instantaneously, causes  a minute decrease of the negative grid voltage. The  effect of this is to make the beam stronger at the precise  instant that it is deflected. This is just what we want  for the strobe effect, which, as we saw, was the brighten-  ing of the spot at one point of the pencil travel; in most  radar circuits the strobe effect, which is puzzling for a  . 
 Accurate  height information is extracted using amplitude monopulse techniques by compar - ing receive energy in adjacent beams. A narrow azimuth beamwidth on transmit and  receive and stacked receive beams provide good radar angle resolution. Azimuth cov - erage of 360 ° is achieved by rotating the array at a nominal surveillance rate. 
 It does not take account of dissipative losses. The power gain, which will be denoted  by G, includes the antenna dissipative losses, but does not involve system losses arising from  mismatch of impedance or of polarization. It can be defined similarly to the definition of  p.2)RADAR ANTENNAS 225 Theradiation patternshowninFig.7.1isplottedasafunction ofoneangularcoordinate, buttheactualpatternisaplotoftheradiation intensity P(O,cP)asafunction ofthetwoangles oand¢y.Thetwoanglecoordinates commonly employed with ground~based antennas are azimuth andelevation, butanyotherconvenient setofanglescanbeused. 
 Suitable applications include sea ice cover, large icebergs,  continental ice sheets, vegetation, and soil moisture.127–130 ch18.indd   55 12/19/07   5:15:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 SEC.8] RADAR BEACONS 245 a b F1a. 8.2 (!.—Radarand beacon signals ofa3-cm radar set:(a)shows only thera, :b)rjhows thebeacon reply; both were received atnearly thesame positdarech ion.oea,. 246 RADAR BEACONS [SEC. 
 Bidwell, D. M. Gragg, and C. 
 Oneexplanation postulated forexplaining this discrepancy isthatenergycanbescattered intoandoutoftheelevated ductbyirregularities in theindex-of-refraction profile. El'aporation ducl.Theevaporation ductthatliesjustabovethesurfaceoftheseaisaresultof thewatervapor,orhumidity. evaporated fromthesea.Theairincontact withtheseais saturated \~thwatervapor,withasaturation vaporpressure appropriate tothetemperature oftheseasurface. 
 16, pp. 29-32, May, 1973.  13. 
 J. Gostin, “The GE592 solid-state radar,” IEEE EASCON 1980 , pp. 197–203. 
 DOPPLER ARCHITECTURE ARE MORE DRAMATIC IN THE UNAMBIGUOUS DOPPLER CLUTTER CASE 02) 
 By filling the center slot of the toroid with high dielectric-constant  material a better figure of merit and lower switching power are obtained, but the peak power  capability is decreased. The individual toroids are usually separated by thin diet~ctric spacers  to avoid magnetic interaction (Fig. 8:IOh). 
 It can be seen that the focus of the image has been signiﬁcantly improved compared with the basic MAM method, but the comparison between these two methods is not obvious. Therefore, a strong scatterer in the small red square is chosen as shown in Figure 11c,d to further compare the two methods. Figure 12is the azimuth impulse responses of the chosen strong scatterer based on the IMAM method and the EMAM method. 
 The rmsaccuracies arebetween 0.05and0.1beamwidth intheseregions:BThechoiceof technique topermittracking oftargetsatlowaltitude withreduced errordepends onthe degreeofcomplexity thatcanbetolerated fortheamount ofimprovement obtained. Electro-optical devicessuchasTV,IR,orlaserscanbeusedinconjunction withradarto providetracking atlowtargetaltitudewhentheradarerrorsareunacceptable. Thesedevices, however, areoflimitedrangeandarenotall-weather. 
 27,  1945.  49. Barlow, E. 
 beamwidth, sidelobes, and boresight error) of a metal space­ frame radome. assuming a uniform or nearly uniform distribution of space-frame elements  over the surface of the radome.104  The ruhheri1cd air-supported radome is an example of a tliin wall radome in which the  thickness of the wall is small compared to a wavelength. A thin-wall ratlomc can also he  constructed of plastic with low dielectric constant and low loss tangent This type of radome  apprnximarcs a rhi11 shell where the loads and stresses are carried in the shell membrane itself. 
 Energy propagates directly from the radar to the target, but  there can also be energy that travels to the target via a path that includes a reflection from the  ground. The direct and ground-reflected waves interfere at the target either destructively or  constructively to produce nulls or reinforcements (lobes). The lobing that resuhs causes non­ uniform illumination of the coverage, and is an important factor that influences the capability  of a radar system. 
 11, pp. 121–131,  1973. 46. 
 Ridenour (ed.), Radar System Engineering , MIT Radiation Laboratory Series, V ol. 1,  New York: McGraw-Hill Book Company, 1947, p. 76. 
 Brook and P. Krehbiel, “A fast-scanning meteorological radar,” in 16th Conf. Radar Meteorol .,  AMS, Boston, 1975, pp. 
 (0) Knife edge (ridqe) (b) Bed of s~ikes  Figure 11.13 Classes of ambiguity diagrams: (a) knife edge, or ridge; (b) bed of spikes,; (c) thumbtack.  (From G. ).V. 
 One is the c*ontjrcttvc. cell or pllirnr that occurs in  the lower part of the atmosphere. The other is the ntmosplte~~ic hori~orltnl luyrr that can occur  at any altitude. 
 LOOK AZIMUTH RESOLUTION FROM A SPACE 
 TION  TO CANCEL DIRECTION INTERFERENCE JAMMING OR CASUAL %-)   THE BEAM RESPONSES "       "      
 TUDE 7HEN WEIGHTING IS APPLIED TO REJECT CLUTTER AND CONTROL T HE FILTER SIDELOBES  THE  PEAK OUTPUT SIGNAL 
 FREQUENCY #7 JAMMING AND SWEPT SPOT NOISE JAM 
 £n°xä  2!$!2 (!.$"//+  FROM AN ELLIPTICAL ORBIT WAS OF LITTLE CONCERN TO THE BUDGET 
 MONTH GEODETIC MISSION HAS BECOME THE BACKBONE OF THE GLOBAL BATHYMETRIC CHART THAT IS THE INDUSTRY STANDARD    'EOSATS SECONDARY MISSION WAS TO OBSERVE DYNAMIC MESOSCALE OCEANO 
   3EPTEMBER   * 4 2ICKARD AND ' - $ILLARD  h!DAPTIVE DETECTION ALGORITHMS FOR MULTIPLE 
 FIGURE 21.4  Losses for GPR signal versus range (Courtesy IEE)Range in metresR0 1 2 3 4 5 6 7 8 9 1 0 10 01010 0 −10 −20 −30 −40 −50 −60 −70 −80 −90−90Signal level in dB Reference Fixed lossesSpreading lossAttenuation Noise floorClutter ch21.indd   9 12/17/07   2:51:15 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 
 Radars with "moderate"  resolution might require only enough improvement factor to deal with the median clutter  power, which may be 20 dB less than the average clutter power.45 According to Shrader a  medium-resolution radar with a 2ps pulse width and a 1.5" beamwidth, is of sufficient resolution  to achieve a 20 dB advantage over low-resolution radars for the detection of targets in ground  clutter.'O  Equipment instabilities. Pulse-to-pulse changes in the amplitude, frequency, or phase of the  transmitter signal, changes in the stalo or coho oscillators in the receiver, jitter in the timing of  the pulse transmission, variations in the time delay through the delay lines, and changes in the  pulse width can cause the apparent frequency spectrum from perfectly stationary clutter to  broaden and thereby lower the improvement factor of an MTI radar. The stability of the  equipment in an MTI radar must be considerably better than that of an ordinary radar. 
 MANCE (OWEVER  TROPOSCATTER SCATTERING COULD BE AN IMPORTANT CONSIDERATION IN TARGET DETECTION BY A RECEIVER NOT CO 
 TER BANK FOR MAIN 
 LUTION OF A SHORT PULSE WITH THE ENERGY OF A LONG PULSE )T IS  DIFFICULT TO PHASE OR FRE 
 Themoving-window detector has nopriorknowledge ofthetargetbeginning. Itmustbesufficiently sensitive toquicklydetecta regionofincreased densityofIs,yetitmustnotbesosensitive thatitinitiates falsealarmsdue tonoise.Onceatargetbeginning isrealized, thedetector mustbeabletosensetjeendofthe regionofincreased-density ofIs.Again,ifitistoosensitive tochange,thedetector willtendto splittargets. I ' .1 Tapped-delay-line integrator. 
 V . Gregers Hansen, “Constant false alarm rate processing in search radars,” in Radar — Present  and Future , IEE Conf. Publ. 
 7.2. With this addition, the de- vice draws onamap the actual ground track made good bythe aircraft carrying theinstrument. Vari- ousmap scales can beselected fortheplotting table bymeans ofaknob onthe control box. 
 TRACKING RADAR169 0.5 0.4. 0.2 0 t::.B ~ Bo·--0.2- --04 --0.6 '- -0.8- -1.0 0?O <106080100120140160180 Phasedifference ~ FigureS.UPlotofEq.(5.2).Apparent radarcenterL10oftwoisotropic scatterers ofrelativeamplitude a andIclativcphascshinIJ..scparatcd byanangular extentOv. flightpathorfromthechanging aspectcausedbytargetmotion. 
 TED WAVEGUIDE ARRAYS USED ON %23 
 CFAR, however, is not without its disadvantages and can be  considered a necessary evil. It introduces an additional loss compared to optimum detection,  and in some systems the number of pulses processed needs to be large to keep the loss low.  More important, CFAR maintains the false-alarm rate constant at the expense of the probabil-  ity of detection. 
 the system is expressed as a noise temperature rather than as a noise factor or noise figure', these terms are defined and interrelated in Sec. 2.5. The noise temperature of the radar receiver has been reduced to the point that it no longer represents a dominant influence in choosing between available alter- natives. 
 534 tNTRODUCTION TO RADAR SYSTEMS  Figure 14.8 Spectl-t~m \he radar echo from the .,ra obtained from an area about 9.5 by 7.5 km via  groundwave propag;ition. The sea was developed by a 25-knot approaching ~ind. Radar frcqi~rncy was  13.4 MHz producing .i resonant doppler frequency shift of 0.37 HL. 
 /- 4HE !UTHOR WISHES TO WARMLY THANK HIS COLLEAGUES FOR THEIR COOPERATION IN THIS WORK  $R , 4IMMONERI  $R , /RTENZI  AND $R % !NDRETA 3%,%8 3ISTEMI )NTEGRATI  )TALY   $R ' ! &ABRIZIO $34/  !USTRALIA   $R 5 .ICKEL &'!.  'ERMANY   0ROF , #HISCI  $R ! "ENAVOLI  AND $R 3 2OMAGNOLI 5NIVERSITY OF &LORENCE  )TALY   $R - 'RAZZINI %LETTRONICA 3P!  )TALY   AND $R 3 +OGON -)4  ,INCOLN ,ABORATORY  53 .   %,%#42/.)# #/5.4%2 
 The Multi-Application Purpose SAR28 is a joint Brazilian-German  enterprise aimed primarily at assessing and monitoring Brazil’s natural resources.  After several years of trade studies, L band was selected (1.3 Ghz). The radar is built  around a near-symmetrical reflector (7.5 m by 5 m) with ten feeds, offset from the  focal point so that the beam can be electronically scanned in elevation. 
 PROTECTORS ARE DESIGNED TO BE NONLINEAR DURING THE TRANSMITTED PULSE AND REFLECT THE INCIDENT ENERGY BACK TOWARD THE ANTENNA )SOLATORS OR CIRCULATORS ARE OFTEN EMPLOYED TO ABSORB MOST OF THE REFLECTED FUNDAMENTAL  BUT THEY ARE GENERALLY MUCH LESS EFFECTIVE AT THE HARMONICS -OREOVER  THESE FERRITE DEVICES ARE NONLINEAR DEVICES AND CAN GENERATE HARMONICS 3PURIOUS DOPPLER SPECTRA ARE CREATED BY ANY PROCESS THAT DOES NOT REOCCUR IDENTI 
 However, the taper efficiency is not an  ohmic loss where energy is dissipated, but is a redistribution of energy. In the case of  a reflector fed by a horn, the taper distribution is determined by the feed horn pattern,  the distance to the reflector, and the projected area in the direction of peak radiation.  For a radially symmetric feed and reflector, where the field is radially symmetric and  Fgrid(x,y) = g(r), the efficiency, h, is computed as  ηπ π π=∫ ∫ ∫g r r dr g r r dr r dr( ) ( )2 2 22 2  (12.10) Spillover Loss. 
 Barker Codes.  A special class of binary codes is the Barker18 codes. Barker codes  are binary codes with peak time sidelobe levels equal to –20log( N), where N is the  length of the code. 
 REPEAT PERIOD AND THE LATITUDE OF THE SITE OF INTEREST 4HE OFF 
 H.: Design of Radiating Elements for Large Planar Arrays: Accomplishthents and Re­ maining Challenges, Microwai·e J., vol. 15, pp, 27-34, September, 1972.  80. 
 In a previous paper, authors introduced a preliminary work dealing with this problem and able to obtain good-quality images, if compared to the standard processing techniques. In this work, the proposed technique is described, and performance parameters are extracted to compare the proposed approach to RD, showing good adherence of the focused images and pulse responses. Keywords: SAR system; efﬁcient focusing of SAR data; inverse problem; remote sensing; SAR data-focusing; synthetic aperture radar; Singular Value Decomposition; blind deconvolution; signal processing; parameter estimation; computational modeling 1. 
 7.19. The phase velocity in parallel-plate waveguide is greater than that  in free space; hence the index of refraction is less than unity. This is opposite to the usual  optical refracting medium. 
 22.6. When the grazing angle is 70° and the reflectivity of the ground is -15 dB, the main- beam clutter cross section is +57 dBsm. If the desired radar performance re- quires that a target with an RCS of +13 dBsm have an SCR of 25 dB, then the main-beam clutter cancellation ratio must be at least 69 dB. 
 of IEEE Radar Conf . 1998,  Dallas, TX, May 11–14, 1998, pp. 56–61. 
 Section 4illustrates our experimental results to validate our proposed methods. Finally, Section 5concludes the paper. 2. 
 Radar has been used extensively for the study of thunderstorms, squall lines,  tornadoes, hurricanes, and in cloud-physics research. Not only is radar useful as a means of  studying the basic properties of these phenomena, but it may also be used for gathering the  information needed for predicting the course of the weather. Hurricane tracking and tornado  warning are examples of applications in which radar has proved its worth in the saving of life  and property. 
 Technique 4.  The MTD approach is described in Section 2.2. Technique 5. 
 DOPPLER CELLS IN A LOOK -ULTIPLE LOOKS WITH DIFFERENT 02&S OR FREQUENCY MODULATIONS ARE USED TO RESOLVE  RANGE ANDOR DOPPLER AMBIGUITIES 4HIS GROUP OF LOOKS IS A DWELL ! DWELL IS ASSOCIATED WITH A PARTICULAR ANTENNA LINE 
 24.9, but in January, (a) 1800 UTC for day. (b) 0800 UTC for night.Height (km) Height (km) . GMT Time FIG. 
 This is a simpler, albeit less accurate, method. It is based on calculating the reduction in  signal power and thus does not depend on the probability of detection. It applies for detection  probabilities in the vicinity of 0.50, but it is used as an approximation with other values as a  matter of convenience. 
 This is called an analog phase  shifter since a continuous phase change is obtained as a function of the current through the  solenoid. It is a reciprocal device in that the phase shift is the same for both directions of  propagation. When it was introduced, the Reggia-Spencer phase shifter had a higher figure of  rnerit (defined as the degrees of phase shift per dB of loss) than previous analog ferrite phase  shifters, and was more compact. 
 Dependence on Wind Speed. The relation between sea clutter and wind speed is complex and uncertain, since it has been found to depend on almost all the parameters that characterize sea clutter: frequency, grazing angle, polariza- tion, the state of the sea surface, the direction and speed of the wind itself, and even on whether the measurements are made from an aircraft or a tower platform.30 A common way to organize clutter data is to seek the best straight-line fit (linear regression) between clutter cross sections in decibels and the log of the wind speed (or some other parameter). This, of course, imposes a power-law re- lation between the variables: <r° « (/", where n is determined by the slope of the . 
 Optimum is from Fig. 15.19. Fast Fourier Transform Filter Bank. 
 (ALL    PP n  * , !LLEN  h4HE THEORY OF ARRAY ANTENNAS v -)4 ,INCOLN ,AB 2EPT   *ULY   * 2UZE  h0HYSICAL LIMITATIONS ON ANTENNAS v -)4 2ES ,AB %LECTRON 4ECH 2EPT   /CTOBER      4 # #HESTON  h%FFECT OF RANDOM ERRORS ON SIDELOBES OF PHASED ARRAYS v  )%%% !03 .EWSLETTER !NTENNA $ESIGNERS .OTEBOOK  PP n  !PRIL   * &RANK AND * 2UZE  h3TEERING INCREMENTS FOR ANTISYMMETRICALLY PHASED ARRAYS v  )%%% 4RANS   VOL !0 
 There is, however, continuous interaction of the electron beam and the RF field over  the entire length of the microwave propagating structure of the TWT as compared  to the klystron where the interaction occurs only at the gaps of a relatively few reso - nant cavities. The TWT was originally conceived with a helix as the slow-wave RF  structure, as in the illustration shown in Figure 10.2. The electron beam is similar to  FIGURE 10. 
 DEPENDENT PHASE AND AMPLITUDE RIPPLE MAY RESULT FROM IMPROPER USE OF THIS CONFIGURATION ! SPLITTER AND COMBINER NETWORK MAY ALSO PROVIDE SERIAL ISOLATION AMONG CAS 
 C., arid L). W. Burlage: Design Procedure for Improving tlie Usable Bandwidth ofan MTI  itatlar Signal Proccssor. 
 Thus, ϕis considered to be the squint angle of beam center. In Figure 8, the squint angle rotates with a constant angular velocity in acquisition time. k=k0(sinθcosϕ, sin θsinϕ, cos θ)is the transmit vector of the radio waves as well ask⊥=k0(cosϕ, sin ϕ)is the projection of the transmit vector in horizontal plane. 
 Phase of  the rdlcctcd wave lags the phase of thelincidcnt wave. (From Burrows and Artwood,5 courtesy Academic  f'ress. Inc.)  For a rough, perfectly conducting surface, such as the sea, Ament 70 derived the reflection  coefficient as  p0 exp [ -2k2h2 s1n2 !/I]  where /lo = complex rellection coefficient for a smooth surface  k 2rr/J  ~ = wavelength  /i2 = mean-square surface height (mean value or lz = 0)  tjJ = grazing angle  Experimental data taken over the sea fit this expression well; except for large values of the  roughness {arameter [(h sin tjl)/).. 
 76.Tong,P.S.:Quantization Requirements inDigitalMTI,IEEETrailS.,vol.AES-13, pp.512-521, September, 1977. 77.Cantrell, B.H.:AShort-Pulse AreaMTI,NRLReport8162,NavalResearcll Laboratory, Washington, D.C.,Sept.22,1977.. MTI AND PLI1.SE 1)OPPI.ER RA1)AR 151  7H. 
 RESOLUTION SPECIFICATION RESULTS FROM AN EXTERNAL CONSTRAINT  THE MAXIMUM   -(Z BANDWIDTH STIPULATED BY INTERNATIONAL SPECTRAL ALLOCATION AGREEMENTS 4HERE IS PROVISION FOR ALL POLARIMETRIC CONFIGURATIONS 4HE SUN 
 Hitney: The EITect of the Evaporation Duct on Microwave Propagation,  Nai•al Electronics Lahoratory Center, San Diego, California, Technical Report 1949, Apr., 17 1975.  79. Hitney. 
 214 7.3 Aids toPlotting and Control 218 7.4 The Relay ofRadar Displays. 225 EXAMPLES OFRADAR ORGANIZATIONS 226 7.5 Radar inthe RAF Fighter Command 226 7.6 The U.S. Tactical Air Commands 229 7.7 Close Control with SCR-584 238 7.8 Teheran .......... 
 Controls (usually automatic) are provided to adjust weights  for operational conditions around the design value. The development of digital radar technology and economical high-speed processors  allows the use of dynamic space-time adaptive array processing (STAP),16 whereby  a set of antenna patterns that displace the phase center of the array both along and  orthogonal to the array are continually synthesized to maximize the signal-to-clutter  ratio. Spatial adaptive array  processing combines an array of signals received at the  same instant of time that are sampled at the different spatial locations corresponding  FIGURE 3. 
 69. G. S. 
 M., et al.: RCS Calculation of Simple Shapes—-Bistatic, chap. 5, "Methods of Radar Cross-Section Analysis," Academic Press, New York, 1968. 93. 
 S.. arid M. W. 
 !LARM #ONTROL  )N THE PRESENCE OF CLUTTER  IF FIXED THRESHOLDS ARE USED WITH  THE PREVIOUSLY DISCUSSED INTEGRATORS  AN ENORMOUS NUMBER OF DETECTIONS WILL OCCUR AND WILL SATURATE AND DISRUPT THE TRACKING COMPUTER ASSOCIATED WITH THE RADAR SYSTEM &OUR IMPORTANT FACTS SHOULD BE NOTED L ! TRACKING SYSTEM SHOULD BE ASSOCIATED WITH THE AUTOMATIC DETECTION SYSTEM THE  ONLY EXCEPTION IS WHEN ONE DISPLAYS MULTIPLE SCANS OF DETECTIONS  L 4HE 0FA OF THE DETECTOR SHOULD BE MATCHED TO THE TRACKING SYSTEM TO PRODUCE THE  OVERALL LOWEST  3. REQUIRED TO FORM A TRACK WITHOUT INITIATING TOO MANY FALSE TRACKS  SEE &IGURE   LATER IN THIS CHAPTER  L 2ANDOM FALSE ALARMS AND UNWANTED TARGETS EG  STATIONARY TAR GETS  ARE NOT A PROB 
 TANK EXPERIMENT WITH DUAL VIBRATING PROBES  !LL RADAR ANGLE 
 Interest in millimeter-wave applications stems from the  special properties exhibited by radar at these frequencies, as well as from the challenge of  exploiting a region of the spectrum not widely used. The major attributes of the mtllimeter-  wave region of interest to radar are the large bandwidth, small antenna size, and the character-  istic wavelength. Large bandwidth means that high range-resolution can be achieved. 
 The antenna pattern of a Luneburg lens lias a slightly narrower beamwidth than that of a  ~>;~~;tl~oloiditl reflector of tlic s;ttr~c circul:~r cross scctiori, but tlie sidelohe level is greater. 56 60  'I liis is due to tlic fact that tlie paths followed by the rays in a Luneburg lens tend to  coricetitrate energy toward the edge of tlie aperture. This makes it difficult to achieve extremely  low sidclobes. 
   3!2 MODES DEVELOPMENT AND  UTILIZATION v #ANADIAN * 2EMOTE 3ENSING  VOL   PP n    # :ELLI  h%.6)3!4 2! 
 OUT DURING THE TRANSMITTED PULSE OR MISTUNING OF THE COHO OR STALO PERMITS THE RECEIVED PULSES TO BE SIGNIFICANTLY DETUNED FROM THE INTENDED )& FREQUENCY )F A  
   COOPERATIVECOMPLETES THE TAXONOMY ! DEDICATED TRANSMITTER IS DESIGNED AND   CONTROLLED BY THE BISTATIC OR MULTISTATIC RADAR  ANALOGOUS TO A MONOSTATIC RADAR  "OTH COOPERATIVE AND NONCOOPERATIVE TRANSMITTERS ARE TRANSMITTERS 
 38. F. T. 
 The unwrapped phase of the reference function in either range or azimuth was approximated by a polynomial function and used to clean up the phase of the reference functions. Stated ythe polynomial function to be used to approximate the unwrapped phase of the reference function, the set of coefﬁcients was computed via a LMS ﬁtting procedure. y=N ∑ i=1ai·xi(7) Here, airepresent the polynomial coefﬁcients and xthe index of samples of the reference function. 
 A. Roy, "The Wind-Speed Measurement  Capability of Spaceborne Radar Altimeters ," IEEE 1. Oceanic Eng. 
 The capability of the human operator as part of the radar detection process can be  determined only by experiment. Needless to say, in experiments of this nature there are likely  to be wide variations between different experimenters. Therefore, for the purposes of the  preserit discussion, the operator will be considered the same as an electronic threshold detec-  tor, an assumption that is generally valid for an alert, trained operator. 
 (With good fixed clutter rejection filters, it takes two or more coherent filters to cover the gap in response at zero velocity.) With the above considerations, a filter bank can be constructed. Figure 15.260 shows the filter designed to respond to targets in the middle of the doppler passband. The sidelobes near zero velocity are 66 dB down from the peak, thus providing good clutter rejection for clutter within 5 percent of zero doppler. 
 POSITE 
 MOISTURE STUDIES   6EGETATION "ACKSCATTER FROM VEGETATION DEPENDS ON  MANY PARAMETERS AND VAR 
 Control problems vary indifficulty from that ofawell-formed group ofaircraft moving over asimple course to that presented bythe requirement foraccurate following orcontrol of numerous aircraft moving over complex independent courses. Aplane flying 300 mph moves $mile in10see, or2*miles in30sec. Data at30-sec intervals, asgiven byascan rate of2rpm, was considered. 
 K. Barton, Radar Resolution and Multipath Effects  in vol. 4 of Radars , Norwood, MA: Artech  House, 1978. 
 TheSqtfultmodeproduces astripmapjustasdoesthesidelooking SAR.Th·.;doppler heam-sharpeni"y modeisusedwithacircularly scanning antenna andanormalPPIdisplay. As thesquintangleofthedoppler beam-sharpening modevaries,theintegration time':hanges to keeptheresolution constant.lThealong-track resolution foreitherthesquintmod,orthe doppler beam-sharpening modeis J.R ()a=2T.0VSill(14.19) wherethesymbols havebeendefined previously. As0decreases inthedoppler beam­ sharpening mode.Tismadetoincrease. 
 GAIN RADAR APERTURES /BVIOUSLY  THE COST OF A SINGLE FEED HORN AND METAL REFLECTOR IS MUCH LESS THAN THE SAME SIZE ARRAY WITH MANY INDIVIDUAL ELEMENTS AND ASSOCIATED PHASE SHIFTERS  AMPLIFIERS  RECEIVERS  ETC #ONSEQUENTLY  MANY RADARS CURRENTLY IN THE FIELD USE REFLEC 
 8 INTRODUCTlON TO RADAR SYSTEMS  Table 1.1 Standard radar-frequency letter-band nomenclature  Band  designation  HF  VHF  UHF  L s  K  K ..  mm Nominal  frequency range  3-30 MHz  30-300 MHz  300-1000 MHz  1000-2000 MHz  2000-4000 MHz  4000-8000 MHz  8000-12,000 MHz  12.0-18 GHz  18-27 GHz  27-40 GHz  40-300 GHz Specific radiolocation  (radar) bands based on  ITU assignments for region 2  138-144 MHz  216-225  420-450 MHz  890-942  1215-1400 MHz  2300-2500 MHz  2700-3700  5250-5925 MHz  8500-10,680 MHz  13.4-14.0 GHz  15.7-17.7  24.05-24.25 GHz  33.4-36.0 GHz  substitute for the actual numerical frequency limits of radars. The specific numerical frequency  limits should be used whenever appropriate, but the letter designations of Table 1.1 may be  used whenever a short notation is desired. 
   !$ 
 A series approximation valid when RA/$o % 1, A 9 I R - A 1, and terms in  A- and beyond can be neglected is9  VT - A 1 + (VT - A)2/$o  X [I- 4~-- + - - ...  8A 2/rC/0  where tlie error fu~lction is defined as  erf Z = -  A graphic illustratior~ of the process of threshold detection is shown in Fig. 2.6. 
 I, AMS, Boston, 1986, pp. 44–47. 188. 
 INGS HAVE BEEN RECORDED ON A  MINUTE CYCLE  SCANNING FROM  TO  OR OPTIONALLY   -(Z   %IGHT SIMULTANEOUS BEAMS SPANNING A  n ARC ARE FORMED 0RIOR TO    THE SYSTEM USED A SINGLE RECEIVER SCANNING THE  RECEIVE BEAMS  SERVICING EACH RECEIVE BEAM FOR  K(Z OF EACH  K(Z PORTION OF A BACKSCATTER IONOGRAM 0OST 
 28Thisrcsultsin thcmicrowave transistor bcingopcrated withrclatively longpulse-widths andhighduty cycles. Forair-surveillance radarapplication, pulsewidths mightbemanytcnsof microseconds ormure.Dutycyclesoftileorderuf0.1arcnotunusual, whichissignificantly greaterthanthcJutycyclestypicalofmicrowave tubes.Thehighdutycyclespresentspecial constraints onlhcradarsystcmdcsigncr sothatsolid-state transmitters arenotinter­ c1Jangeable withtubetransmitters. Adifferent systemdesignphilosophy usually mustbe employed withsolidstate. 
 BACK VALUE THAT DETERMINES THE MAP TIME CONSTANT  AND ! IS THE CONSTANT THAT DETERMINES  THE 0FA )N THE -4$ USED FOR THE !32 APPLICATION   + IS   WHICH EFFECTIVELY AVERAGES  THE LAST EIGHT SCANS 4HE PURPOSE OF THE CLUTTER MAP IS TO DETECT  IN CLUTTER FREE AREAS  CROSSING TARGETS THAT WOULD HAVE BEEN REMOVED BY THE DOPPLER PROCESSING 4HE MAIN UTILITY OF CLUTTER MAPS IS WITH FIXED 
 NAL PHASE FOR RADAR SIGNALS WITH POSITIVE DOPPLER APPROACHING  TARGETS  &REQUENCY CON 
 Velocity Estimation . The variance of the mean frequency estimate of the doppler  spectrum is  var(ˆ) ( ) fP Tf S f f df r= + ∫1 2 02 2 (19.42) This is an interesting result showing that the variance of the estimate ˆf is a func - tion only of the shape of the doppler spectrum (primarily its spectrum width) and the  integration time T0 allocated for processing. If the spectrum can be accurately modeled  by a gaussian shape with variance σf2, Eq. 
 Theactualsequence obtained depends on boththefeedback connections andtheinitialloadingoftheregister. Whentheoutputse­ qucnceofanII-stagcshiftregisterisofperiod2"-1,itiscalledamaximallengtlJ sequence, or m-sequellce. Thesehavealsobeencalledlinearrecursive sequences (LRS),pseudonoise (PN) sequences. 
 Thedecor­ relation timeofe1utterisusuallymuchgreaterthanthis. Nextconsider thecasewheretheradarobserves surface clutternearperpendicular incidence. (Atperpendicular incidence the'grazing angle</>is900.)Theclutterareaviewedby theradarwillbedetermined bytheantenna beamwidths 08and</>8inthetwoprincipal planes. 
 VIA performance By 1944 an increasing number of U-boats were being equipped with schnorkel (later referred to as snorts in the UK) allowing them to charge their batteries while still submerged. There was clearly a strong requirement to be able to detect a schnorkel by radar, but achievable ranges were usually quite small. It is noted in [ 15] that often at that time in daylight schnorkels were more readily detected by eye, as they often emitted smoke as well as having a prominent wake. 
 To accomplish this the signal processor must provide at least 60 dB improvement factor,  which is a difficult task. 56 Not only must the signal processor be designed to reduce the clutter  by this amount, but the receiver must be linear over this range, there must be at least eleven  bits in the A/D converter of the digital processor, the equipment must be sufficiently stable,  and the number of pulses processed (for reducing antenna scanning modulation) must be  sufficient to achieve this large value of improvement factor.  4.9 NONCOHERENT MTI  The composite echo signal from a moving target and clutter fluctuates in both phase and  amplitude. 
 Coleman, “Discriminants for assigning passive bearing observations to radar targets,” in  IEEE Int. Radar Conf ., Washington, DC, 1980, pp. 361–365. 
 This usage has continued and is now an accepted practice of radar  engineers. Table 1.1 lists the radar-frequency letter-band nomenclature adopted by the  IEEE.' These are related to the specific bands assigned by the International Telecommunica-  tions Union for radar. For example, although the nominal frequency range for L band is 1000  to 2000 MHz, an L-band radar is thought of as being confined within the region from 1215 to  1400 MHz since that is the extent of the assigned band. 
 TIMES OBSERVED  A CRITICAL ANGLE OFTEN FAILS TO MATERIALIZE  AND WHEN IT DOES  IT NEED NOT SHOW AN  2 n DECREASE WITH RANGE EQUIVALENT TO A FOURTH 
 By the mid-1970s, new experimental results were obtained,7,8 which showed that  the spectrum fall-off was slower than predicted by the gaussian model. This led to  new models based on polynomial representations of the spectrum using an equation  of the form:  S fnn Bf Bn POLY( )sin | |=⋅   ⋅⋅ +  π π3 31 12 (2.8) The spectrum shape is determined by the integer n, which must be 4 or larger in  order for the two first spectral moments to exist. A typical value used for this spectrum  is n = 4 which results in  S fBf BPOLY( ) | |=⋅⋅ +  8 1 12 3 34 π  (2.9) The relationship between the standard deviation of this spectrum and its 3-dB width  is given by  Bf 32= ⋅σ (2.10) A potential issue with this model is that the skirts of the spectrum correspond to  very large radial velocity components of the clutter internal motion. 
 ( a) No Doppler parameter estimation; ( b) the basic MAM method; ( c) the IMAM method; ( d) the EMAM method. 62. Sensors 2019 ,19, 213 T able 4. 
 RADAR EQUATION SEE 3ECTION    %##- PERFOR 
 PRESSURE SYSTEMS  LARGE 
 This is especially noted with end-fire elements (such as polyrods or log-  periodic antennas) which are spaced close enough to couple or diffract energy. The effect of  mutual coupling on the input impedance with such elements is usually small. However, the  ciistiirbance to the aperture illumination can be quite large and can result in significant  differences from the pattern computed by ignoring such effects. 
 30-31,  Aug. 18. 1961. 
 Studer, Radar Data Processing , V ol. 2, Advanced Topics and Applications ,  UK: Research Studies Press Ltd., 1986. 29. 
 Thesegratinglobescancauseambiguities inthemeasurement. Theambiguities can beresolved byuseofmorethantwoantennas withunequal spacings. Theoutertwoantennas provide accurate, butambiguous, measurement ofelevation angle.Thefunction oftheoneor moreinnerantennas istoresolvetheambiguities. 
  PRECISION TRACKING RADAR v IN  )%%% )NT 2ADAR #ONF 2EC   !RLINGTON   6!    PP n  $ $ (OWARD  h3INGLE !PERTURE MONOPULSE RADAR MULTI 
 Barlow, “Aperture uncertainty and ADC system performance,” Analog Devices  Application Note AN-501, Rev. A, March 2006.  7. 
 Constrained metal-plate lenses are capable of wide scan angles as compared to  the limited scanning possible by moving the feed in a paraboloid reflector.  The lens is usually less efficient than comparable reflector antennas because of loss when  propagating through the lens medium and the reflections from the two lens surfaces. In a  zoned lens there will be additional, undesired scattering from the steps. 
 CONTROLLED VACUUM TUBE WELL INTO THE EARLY PART OF THE CURRENT CENTURY )T HAS  BEEN A VERY COMPETITIVE POWER SOURC E FOR 5(& RADAR APPLI 
 TION LEVELS AND LONGER RADAR RANGES  NEITHER OF WHICH ARE DESIRABLE IN MOST SITUATIONS 3PACECRAFT VELOCITIES AT THESE ,%/ ALTITUDES ARE ON THE ORDER OF  KMS THEIR COR 
 TIME &IG  A    FREQUENCY IS IN HERTZ AND IS REPRESENTED BY  & )N DISCRETE 
 Picardi,   A. Masdea, and E. Zampolini, “SHARAD: the MRO 2005 shallow radar,” Planetary and Space  Science , vol. 
 Unterberger, “Radar and sonar probing of salt,” in 5th Int. Symp. on Salt , Hamburg  (Northern Ohio Geological Society), 1979, pp. 
 Sea Ice.  Sea ice is a very complex medium. Ice observers characterize it in  many different categories that depend on thickness, age, and history of formation.152  Hence, one cannot characterize its radar return in any simple way; in this sense, it is  like vegetation. 
             )#-  %' %     #&  ''. ),+(,+ !!# # & /  & #& &)'52%   4YPICAL  
 LAW FIT COMPARE DATA POINTS WITH  THOSE IN &IGURE   AFTER ! ( #HAUDHRY AND 2 + -OORE  Ú )%%%   .   3%! #,544%2  £x°£x &)'52%   ! REPRESENTATION OF 8 BAND  UPWIND CLUTTER BEHAVIOR WITH WIND SPEED AND GRAZING ANGLE  A  VERTICAL POLARIZATION AND B   HORIZONTAL POLARIZATION &)'52%   $EPENDENCE OF CLUTTER ON WIND DIRECTION NOMINAL WIND SPEED   KT GRAZING ANGLE  ABOUT  UPWIND     AND DOWNWIND   AFTER ( -ASUKO ET AL  Ú !MERICAN 'EOPHYSICAL  5NION   . 
 In the ARSR-3, the weather information is available at the ortho-  gonal port of tlie circular-polarization diplexer and can be viewed by switching this output to  tlic display.  Frequency considerations. Tlie ARSR-3 described above operates at L band (1250 to  1350 M H7). 
 16. Kerr, D. E. 
 When the sum S = D, + Dr approaches the base-line distance Dbr the prolate sphcroid  degenerates into a'straight line joining the two foci. Under these conditions, the location of the  target position is indeterminate other than that it lies somewhere along the line joining tile  transmitter and receiver. .)  Locati'ng a target with bistatic radar is not unlike locating a target with monostatic radar. 
 Burgess: An Adaptive AMTI Radar Antenna Array, Proc. IEEE 1974 Null.  Aerospace and Electronics ConJ, May 13-15, 1974, Dayton, Ohio, pp. 
 From the early 1938 days it had been realized by  Watson-Watt and his co-workers that greater accuracy  was needed. Nothing but a narrow beam of radio  waves, instead of the ‘floodlighting’ technique, would  suffice; this meant higher power, to concentrate the  beam, greater sensitivity at the receiver, and a much  shorter wavelength. Early radar had been effected with  transmitters on 50 metres, then 12 metres, and subse-  quently right down to 2 metres; but this was yet not  short enough to produce a pencil-like beam, for reasons  we will consider in a later chapter. 
 In a single- channel 0.5-duty-cycle system, one pulse-suppressor circuit serves both functions. In multiple-range-gated systems the range gates can serve both functions. If one circuit serves both functions, the on-off ratio must be adequate for pulse suppression, whereas if two are used, the range gate does not need as much rejection. 
 NOISE RATIO #HOOSING THE PROPER WEIGHTING IS A COMPROMISE BETWEEN REJECTING MAIN 
 ING ON THE TYPE OF RADAR AND MODE OF OPERATION 0ROCESSING SUCH AS PULSE COMPRESSION  DOPPLER PROCESSING  AND MONOPULSE COMPARISON  ALL REQUIRE AMPLITUDE AND PHASE INFOR 
 __ 7"!Pa,A2<Jf pts  -64N o000;(S/N)LsOr ( 14.24)  Lumping into a single constant K the constants in this equation and the parameters assumed  to be given (including 0,.) or not under the control of the radar designer, we get  R4 = K !'av  Oa (14.25)  Thus a measure of the perrormance of an HF surveillance radar is the ratio of the average  power divided by the azimuth beamwidth. When comparing the performance of two radars  with different antenna heights as well as different widths, a measure of relative performance is  Measure of performance= Pa,· wh2 (14.26)  where w = antenna width and It = antenna height. If separate antennas are used for transmit  and receive, w is the width of the receiving antenna and lt2 is replaced by h, hr where  Ii, = transmitting antenna height and hr = receiving antenna height. 
 Wang, and Q. Xu, “SAW pulse compression systems with lower sidelobes,”  1997 Asia Pacific Microwave Conference , pp. 833–835. 
 PROOFED BROADBAND COMMUNICATION SYSTEMS  MEAN THAT THE COSTS OF A MORE OPTIMIZED RADAR HEAD OFTEN BECOME A RELATIVELY  INSIGNIFICANT ADDI 
 293-328. 1958. 6(i INTRODUCTION TO RADAR SYSTEMS  26. 
 $IFFERENCE 4IME 
 (3)shows that the repetition rate enters into the stability condition. However, weshall assume, forsimplicity, that the over-all system instability isindependent ofAand jr. 16s10. 
 The drive  power to the T.WT is 50 mW.  6.7 c;1u1>-CONTROLLEI> TUBES  The early radars developed during the 1930s used conventional grid-controlled vacuum tubes  since there existed 110 other source of large RF power. This limited the development of the  early radars to the VHF and the lower UHF bands. 
 FIELD AMPLIFIER TRANSMITTER NEEDS MORE THAN ONE STAGE OF 2& AMPLIFICATION  EACH WITH ITS OWN POWER SUPPLY  MODULATOR  AND CONTROLS !LL THESE STAGES MUST BE STABLE TO ACHIEVE GOOD -4) PERFORMANCE. 
 The  droplet sizes of freezing rain, however, are large and the collection efficiency can approach 100  percent. Dry snow does not stick to cold surfaces and is generally no problem. Snow might  collect on the top portion of the radome but will be quickly removed by any following wind. 
 SUPPORT JAMMING IS IN THE COORDINATED TACTICS THAT CAN BE EMPLOYED ! FAVORITE TACTIC EMPLOYED AGAINST TRACKING RADARS  FOR EXAMPLE  IS TO SWITCH BETWEEN JAMMERS LOCATED ON SEPARATE AIRCRAFT WITHIN THE RADARS BEAMWIDTH 4HIS BLINKING HAS THE EFFECT OF INTRODUCING ARTIFICIAL GLINT INTO THE RADAR TRACKING CIRCUITS  WHICH  IF INTRODUCED AT THE PROPER RATE TYPICALLY  TO  (Z   CAN CAUSE THE RADAR TO BREAK ANGLE TRACK )N ADDITION  BLINKING HAS THE DESIRABLE EFFECT OF CONFUSING RADIATION HOMING MISSILES THAT MIGHT BE DIRECTED AGAINST THE JAMMER RADIATIONS  3TAND 
 Furthermore, if the target height is to be referenced to the local terrain, then the height of that possibly irregular terrain below the target must also be taken into account. The effects of some of the systematic internal equipment errors can also be partially offset by incorporating internal calibration measurements into the range and an- gle estimation algorithms. Flat-Earth Approximation. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°Èx  4 -ISRA  3 3 2ANA  6 ( "ORA  . - $ESAI  # 6 . 2AO  AND . 2AJEEVJYOTHI  h3!2 PAYLOAD OF  RADAR IMAGING SATELLITE 2)3!4  OF )32/ v IN  0ROCEEDINGS  TH %UROPEAN #ONFERENCE ON 3YNTHETIC  !PERTURE 2ADAR  $RESDEN  'ERMANY  6$% 6ERLAG    2 3CHROEDER  * 0ULS  & *OCHIM  * 
   PP n     * , -AC!RTHUR  # # +ILGUS  # ! 4WIGG  AND 0 6 + "ROWN  h%VOLUTION OF THE SATELLITE RADAR  ALTIMETER v *OHNS (OPKINS !0, 4ECHNICAL $IGEST   VOL   PP n  /CTOBERn$ECEMBER   * , -AC!RTHUR  0 # -ARTH  AND * ' 7ALL  h4HE '%/3!4 RADAR ALTIMETER v  *OHNS (OPKINS  !0, 4ECHNICAL $IGEST   VOL   PP n    7 ( & 3MITH AND $ 4 3ANDWELL  h"ATHYMETRIC PREDICTION FROM DENSE SATELLITE ALTIMETRY AND  SPARSE SHIPBOARD BATHYMETRY v * 'EOPHYS 2ES  VOL   PP n    $ 4 3ANDWELL AND 7 ( & 3MITH  h"ATHYMETRIC ESTIMATION v IN  3ATELLITE !LTIMETRY AND %ARTH  3CIENCES  , 
 1977.  93. Cooke. 
 Modes optimized for this function are invoked throughout a mission. Waveform Variations by Mode.  Although the specific waveform is hard to pre - dict, typical waveform variations can be tabulated based on observed behavior of a  number of existing A-S radar systems. 
 Lewis.13')  7.4 SCANNING-FEED REFLECTOR ANTENNAS  Large antennas are sometimes difficult to scan lllcclia~~ically wit11 irs 11li1clr I1cxil)illty as olic  might like. Some technique for scanning the beam of a large antenna must often be used other  (liar1 the brute-force technique of mechanically positioning the entire structtire. Phased array  antennas and lens antennas offer the possibility ofscanning the beam without tile necessity for  moving large mechanical masses. 
 Surface roughness is a relative measure and depends on the wavelength of the illuminating signal. A surface that appears rough at one wavelength might ap- pear smooth when illuminated with longer-wavelength radiation. Thus another method for determining surface roughness is by varying the frequency of the il- luminating radiation and observing the transition from specular to diffuse scatter. 
 EDL-M1319, 1971. 40. Lucas, D. 
 Beneﬁting from the high spatial resolution of the SAR system, TEC obtained from PALSAR could be orders of magnitude higher in spatial resolution than that from GPS. Besides, we demonstrated that the precision of TEC from PALSAR is also much higher thanthat from GPS. With the precise TEC available, we could fuse it with data from other ionosphere detection devices to improve their performances. 
 OF 
 10.6a, b,and cindicates a fourfold, instead ofeightfold, sym- metry, and shows that the field falls offless rapidly toward the cathode. Experience has shown that magnetron operation inany but ther-mode isunsatisfactory. Possible modes foran8-oscilla- tormagnetron total seven: two 7r/4- modes, two r/2-modes, two 3r/4-modes, and one mmode. 
 1516–1519, 1999. 50. M. 
   -(Z ,23 3%,%.%  ,UNAR SUBSURFACE  -(Z 02 42-- n  2AIN  '(Z -!23)3  -ARS %XPRESS n -ARS IONOSPHERE n -(Z #02 #LOUD3AT  %ARTH CLOUD PROFILES  '(Z $02 '0- n 2AIN    '(Z  HTTPNSSDCGSFCNASAGOCDATABASE-ASTER#ATALOG SC  
 It must be less than unity for  stable operation. The effect of k < 1 is that the integrator has imperfect "memory." The  optimum value of k depends on the number of pulses received from the target (Sec. 2.6 and  Ref. 
 Approximations to Matched Filters. The most efficient filter for dis- criminating between white gaussian noise and the desired echoes is a matched filter, a passive network whose frequency response is the complex conjugate of the transmitted spectrum. It can process echoes from all ranges. 
 There is no necessity here to describe the action of  - the D.C. restorer, for although this circuit is commonly  used with radar CRT’s, the D.C. restoration principle  is well known in connexion with television and cathode-  ray oscilloscope practice. 
 POLARIZATION AS WELL 4HIS AVOIDS THE TYPICAL COMPROMISE AND GREATER COM 
 BANDWIDTH PRODUCT 4"0  SIGNAL !FTER RECEPTION  DEMODU 
 This will produce larger values of s  0 as derived  from measured values of sc by Eq. 15.7. Most experimenters use the half-power  beamwidth in Eq. 
 The methods of implementation are divided into two general classes, ac- tive and passive, depending upon whether active or passive techniques are used for generation and processing. Active generation involves generating the waveform by phase or frequency modulation of a carrier without the occurrence of an actual time expansion. An example is digital phase control of a carrier. 
 CHAPTER 4 LIMITATIONS OF PULSE RADAR BY E.M. PURCELL To athoughtful observer, one ofthe most striking features ofa microwave radar screen isthe quantity ofinformation that isavailable ataglance and continually being renewed. Insome installations the map ofanarea ofmany thousands ofsquare miles isdrawn every few seconds. 
 When  the antenna is directed forward (energy propagating parallel to the radome axis) the angle of  incidence on the radome surface can be in excess of 80°. ln other look directions the incidence  angle might be zero degrees. Since the transmission properties of radome materials varies with  angle of incidence and polarization, the design of an airborne radome to achieve uniform  scanning properties might not be easy. 
 The performance estimates shown  in the figures assume that the radar design and waveforms are such that external noise is  the control. The use of a single description for night and day gives a fair representation,  but the transition from night to day is very abrupt and requires careful frequency man - agement in radar operation. The ionospheric description that has been used is for what  has been termed the quiet ionosphere,  conditions that apply most of the time. 
 111st. Nc.wigatio11 (Lv11do11),  vol. 7. 
 APERTURE 3!2  KEY RESULTS HAVE BEEN OBTAINED BY SEVERAL AUTHORS   INCLUDING 2ANEY  &REEMAN  &REEMAN AND #URRIE  AND 7ERNESS ET AL )F THE  02& IS GREATER THAN THE MINIMUM NECESSARY TO PRODUCE A 3!2 IMAGE  THEN FURTHER DOPPLER BANDS ARE AVAILABLE 4HESE BANDS CAN BE USED FOR ADDITIONAL INFORMATION  AND PROCESSING RESULTS FOR MOVING TARGETS WILL BE DIFFERENT FROM THOSE FOR FIXED TARGETS &REEMAN  PRESENTS A SUMMARY OF POTENTIAL RESULTS FOR MOVING TARGETS  COV 
 ARRAY AND REFLECTORS ANTENNAS v IN  !SPECTS OF -ODERN  2ADAR  % "ROOKNER ED   .ORWOOD  -! !RTECH (OUSE  )NC    7 4 0ATTON  h,OW 3IDELOBE !NTENNAS FOR 4ACTICAL 2ADARS v  )%%% )NT 2ADAR #ONF 2EC    !PRIL n    PP n  ! &ARINA   !NTENNA "ASED 3IGNAL 0ROCESSING 4ECHNIQUES FOR 2ADAR 3YSTEMS   .ORWOOD  -!  !RTECH (OUSE  )NC    & * (ARRYS  h/N THE USE OF WINDOWS FOR HARMONIC ANALYSIS WITH THE $ISCRETE &OURIER 4RANSFORM v  0ROC )%%%  VOL   PP n  *ANUARY   % "ROOKNER  h4RENDS IN RADAR SYSTEMS AND TECHNOLOGY TO THE YEAR  AND BEYOND v IN  !SPECTS  OF -ODERN 2ADAR  % "ROOKNER ED   !RTECH (OUSE  )NC  .ORWOOD  -!    % "ROOKNER  h0HASED 
 PERFORMANCE RADAR  THESE VARIANTS OF THE KLYSTRON ARE LIKELY TO BE HIGHLY FAVORED FOR MANY APPLICATIONS 4HE KLYSTRON HAS GOOD STABILITY AND LOW NOISE SO AS TO ENABLE LARGER -4) IMPROVEMENT FACTORS TO BE OBTAINED WHEN USING THE DOPPLER SHIFT TO DETECT MOVING TARGETS IN CLUTTER !T HIGH POWER  HIGH VOLTAGES HAVE TO BE USED AND PROTECTION FROM 8 
 Amplitude-comparison monopulse. The amplitude-comparison monopulse employs two  overlapping antenna patterns (Fig. 5.7a) to obtain the angular error in one coordinate. 
 Radar System Engineering  Chapter 6 – Radar Receiver Noise and Target Detection  32     For the Sun and the Moon the aspect angles from the Earth are approxim ately 1/2 ° each.  Fig- ure 6.3 shows the Sun, Moon, and Cassiopeia.    Figure 6.4  Noise from radio stars and bodies: Sun, Moon, and Cassiopeia. 
 73. A. Farina and L. 
 Using such techniques, it is possible to estimate the topography of the surface beneath  a vegetated canopy, for example. Applications . SARs are the largest class of space-based remote-sensing radars,  primarily as a result of their practical utility. 
 13.9. Electronic Switches.-An electronic switch isa device that can change the parameters ofthe circuit inwhich itoccurs. The principal functions performed bysuch switches aretocontrol theabsolute potential level ofapoint inthe circuit, andto control thetransmission orgenera- tion ofsignals byswitching them onand offorbychoosing between different signals. 
 DOPPLER  ELEMENTAL 
 The position of the target echo in the frequency spectrum depends upon its velocity  relative to that of the radar aircraft. H the target aircraft approaches the radar aircraft head on  (from the forward sector), the doppler frequency shift of the target will be greater than the  doppler shifts of the clutter echoes, as shown in Fig. 4.36. 
 The ferrite phase shifter is  then latched to the reference phase (0 °).  This change in phase with a change in cur - rent direction is due to the nonreciprocal  nature of the device. As mentioned, early  devices saturated each bit so that a ferrite  toroid and electronic driver were required FIGURE 13.34  Diode phase-shifter configurations ( after L. 
 Co11f Proc .. Fourth  Natl.< ·om·. 011 Military Llcctronics. 
 The conical-scan radar, on the  other hand, integrates a number of pulses first and then extracts the angle measurement.  Because a rnonopulse radar is not degraded by amplitude fluctuations, it is less suscep-  tible to l~ostile electronic countermeasures than is conical scan.  111 brief, the mot~opulse radar is the better tracking technique; but in many applications  where the ultimate in performance is not needed, the conical-scan radar is used because it is  less costly and less complex. 
 Smith. 1:. K.. 
 AP-4, rp. 51-53, January, 1956.  22. 
 Also note that at night the 5-MHz lower frequency limit does not provide coverage closer than about 500 nmi. It should be remembered that this is a me- dian SSN 50 calculation, and if consistent performance for ranges as close as 500 nmi is required during nights, a lower frequency limit should be selected to deal with periods of lower solar activity and the critical frequency distribution. The plots show that operation on a single frequency provides less than ±3 dB varia- tion over a 500-nmi range interval. 
 SIGNAL INFORMATION 4HE DESIGN OF THE MICROWAVE RESOLVER  MUST MINIMIZE LOSS THROUGH THE DEVICE  AND PRECISELY MATCHED )& CHANNELS ARE REQUIRED TO MINIMIZE CROSS COUPLING BETWEEN THE AZIMUTH AND ELEVATION CHANNELS )N SOME MOD 
   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î° BEAMS ARE GENERATED "OTH BEAMS HAVE THE SAME AMPLITUDE VOLTAGE  DISTRIBUTION  &X  BUT DIFFERENTLY INCLINED LINEAR PHASED FRONTS 4HE TOTAL APERTURE EXCITATION WITH  BOTH BEAMS IS  &X &XE &XE &XJX A JX A        C   YYY    O OS        YYYY  
 the direct signal will be highly attenuated by propagation  losses and might be too weak to be detected at the receiver. (The signal scattered by the target  will not be highly attenuated if the target lies above the radar line of sight, but the direct signal  must overcome the losses due to its over-the-horizon path.) Wheri the direct signal is not  available at the receiver. its function may he performed by a stable clock or reference oscillator  synchronized to the transmitter. 
 The Radio ar~d Elrctror~ic Enginerr, vol. 46,  pp. 379 392. 
 FORM COLUMN FORMAT  OBTAINED FROM A NUMBER OF DIFFERENT DATA SOURCES )N ADDITION  CLIMATOLOGICAL REFRACTIVE CONDI 
 The decrease in attenua - tion with increasing wavelength is clearly shown. The values change by about an order  of magnitude for a change of l from 1 to 3 cm. The data presented here also shows  that attenuation in water clouds increases with decreasing temperature. 
 RATE #! 
 This is in contrast to the airborne case for which the FM rate of the azimuth doppler  modulation is proportional to the square of the aircraft velocity. Why the difference?  Rather than a straight line, which is the baseline situation for an airborne system, the  synthetic aperture of a space-borne SAR is formed along an arc. This imposes a small  but significant increase in the effective length of the synthetic aperture and also modi - fies the FM rate. 
 A. Weil, “An introduction to MTI system design,” Electronic Progress , vol. 4, pp. 
 13.8.—Synchro-driven repeater. TheSynchrodriuen Repeater.—If the stators and rotors areattached respectively inparallel and the rotors are connected toana-cpower source (Fig. 13.8), the two rotors will tend toalign themselves inthe same direction. 
 This is sometimes called the Bragg backscattering resorlarlce condi-  tion because of its similarity to the X-ray scattering in crystals as observed by Bragg.' Thus  the radar is responsive only to those water waves which satisfy Eq. (13.13). An X-band radar  (A = 3 cm) at zero degrees grazing angle would backscatter from water waves of length 1.5 cm. 
 458 THERECEIVING SYSTEM—RADAR RECEIVERS [SEC. 12% orlike the noise produced inthe receiver, the more difficult itistodis- criminate against. One type ofinterference that must beguarded against is“hash,” from rotating machinery and steep pulse wavefronts, which may leak into the i-famplifier. 
 METAL 
 Since Rge(j) is the ground range corresponding to Rnew, the DEM data of Rge(j) are also Hnew. () () () () () 22 gn sRj Rj D E Mj =    Figure 9. Flow chart of calculating the sequence Rg. 
       KKKT \    WHERE ( IS THE GRADIENT OF  H %ACH COORDINATE FRAME HAS ITS OWN APPROXIMATION FOR  ( &OR  EXAMPLE  IF THE STATE COORDINATE SYSTEM IS COMPOSED OF THREE 
 STATE MODULES CAN HAVE UNEXPECTED SUSCEPTIBILITY TO VIBRATION 2& CONNECTORS MUST BE SECURE 3HOCK MOUNTS CAN BE USED TO ISOLATE COMPONENTS FROM THE CABINET STRUCTURE )T IS RECOMMENDED THAT ALL 2& COM 
 608--618,  October, 1949.  23. IEEE Standard 686-1917: "JEEE Standard Radar Definitions," Nov. 
   PP n  .OVEMBER   3 ! 3CHELKUNOFF  h! MATHEMATICAL THEORY OF LINEAR ARRAYS v  "ELL  3YST 4ECH *  VOL      PP n  *ANUARY   * & 2AMSAY  * 0 4HOMPSON  AND 7 $ 7HITE  h0OLARIZATION TRACKING OF ANTENNAS v PRESENTED AT  )2% )NT #ONV  3ESSION   !NTENNAS )    0 - 7OODWARD  ! METHOD OF CALCULATING THE FIELD OVER A PLANAR APERTURE REQUIRED TO PRODUCE A  GIVEN POLAR DIAGRAM  * )%% ,ONDON   VOL   PT !  PP n    2 # (ANSEN  h!PERTURE THEORY v IN  -ICROWAVE 3CANNING !NTENNAS   VOL )  .EW 9ORK !CADEMIC  0RESS  PP n  * & 2AMSAY  h,AMBDA FUNCTIONS DESCRIBE ANTENNA DIFFRACTION PATTERN v  -ICROWAVES  PP n   *UNE . £Î°ÇÓ  2!$!2 (!.$"//+   ! +SIENSKI  h%QUIVALENCE BETWEEN CONTINUOUS AND DISCRETE RADIATING ARRAYS v  #AN * 0HYS   VOL   PP n    7 ( 6ON !ULOCK  h0ROPERTIES OF PHASED ARRAY v  )2% 4RANS 6OL !0 
   05,3% $/00,%2 2!$!2   {°£Ç WHERE  62    RADAR GROUND SPEED  K   2& WAVELENGTH  P"    D" ONE 
 The predicted value of the range as found from the radar  equation cannot be expected to be checked experimentally with any degree of accuracy. It is  difficult to determine precisely all the important factors that must be included in the radar  equation and it is difficult to establish a set of controlled, realistic experimental conditions in  which to test the calculations. Thus it might not be worthwhile to try to obtain too great a . 
 TICAL AT FREQUENCIES NEAR  '(Z 6EGETATION DISCRIMINATION IS BETTER  HOWEVER  AT HIGHER FREQUENCIES AND ANGLES OF INCIDENCE &OR SOME APPLICATIONS  USE OF THE FULL POLARIZATION MATRIX  INCLUDING THE PHASE  IS USEFUL 4HE PHASE INFORMATION IS PARTICULARLY HELPFUL IN ASSESSING SCATTERING MECHANISMS  AS IN FORESTS  "ECAUSE THE LITERATURE IN THIS FIELD IS SO MASSIVE  THE RADAR ENGINEER WISHING TO LEARN  MORE ABOUT THE SUBJECT SHOULD CONSULT THE  -ANUAL OF 2EMOTE 3ENSING   -ICROWAVE  2EMOTE 3ENSING  ESPECIALLY 6OL ))) AND #HAPTER  OF 6OL ))  AND THE JOURNALS OUTLINED  EARLY IN 3ECTION  , 
 However, the cancellation will correspond to a value VXTP = 2e in Fig. 16.8. If 2t/Tp is small enough, then the sidelobe clutter spectrum will be in the filter notch and will be canceled. 
 4-11, January 1977. 27. Barrick, D. 
 ARRAY APERTURE MAY BE DIVIDED INTO SUBARRAYS  ALL  SIMILAR TO SIMPLIFY MANUFACTURING AND ASSEMBLY "EAMFORMING NOW REQUIRES COM 
 The feed is placed at one focus of the hyperboloid, and the paraboloid focus  is coincident with the second focus of the hyperboloid. The use of a subreflector also  allows the feed to be located behind the main reflector and closer to the transmitter  and receiver in order to minimize transmission line losses. Furthermore, if the feed is  located behind the main reflector, the center of gravity will be biased closer to the main  reflector vertex thereby simplifying the design of both the structure and the gimbal   (precision mechanical positioning system). 
 TAGE OF USING FEEDFORWARD FOR VELOCITY RESPONSE SHAPING IS THAT AN ADDITIONAL DELAY  AND THEREFORE AN ADDITIONAL TRANSMIT PULSE  MUST BE PROVIDED FOR EACH ZERO USED TO SHAPE THE RESPONSE &IGURE  SHOWS THE VELOCITY RESPONSE AND  : 
 Washington. D.C.. May 29, 1974. 
 F. T. Ulaby and C. 
 Figure 3. (a) change map with dictionary size = 30 atoms with 30 non-zero coefﬁcients; ( b) change map with dictionary size = 15 with three non-zero coefﬁcients. Note that a larger dictionary size with more non-zero coefﬁcients captures more changes. 
 Solid-state limiters. Solid-state PN and PIN diodes can be made to act as RF limiters and are  thus of interest as receiver protectors.42-44 Ideally, a limiter passes low power without attenua­ tion, but above some threshold it provides attenuation of the signal so as to maintain the  output power constant. This property can be used for the protection of radar receivers in two  different!" implementations depending on whether the diodes are operated unbiased (self­ actuated) or with a d-c forward-bias current. 
 CASSINI 
 When the earth's curvature must be considered, these two angles  , are not equal. Tlie incidence angle is preferred when considering earth backscatter effects from  near perpendicular incidence, as in the case of the altimeter. The grazing angle is the preferred  measure in most of the other radar applications, and will be the angle used in this chapter,  Descri#ions presented in this chapter of radar scattering from the land and the sea are by  no means complete. 
  
 Servo-driven variacs have proved useful insuch asituation. Interference fromCommon Loads.—If theloads sharing power service with the radar impose high intermittent demands, and especially ifthe total capacity ofthe system islow with respect tothese loads, serious transient interference may beencountered. Anisolating motor-gener- ator istheonly satisfactory solution forsuch difficulties. 
 LATION DISTORTION PRODUCES SIGNALS AT FREQUENCIES  F n F  F n F  F   F  F   F  F  AND F &OR NARROW BAND SIGNALS  ONLY THE THIRD ORDER PRODUCTS  F n F AND F n F FALL  IN BAND  AND CONSEQUENTLY  THIRD ORDER DISTORTION IS TYPICALLY THE PRIMARY CONCERN 4HE POWER LEVELS OF THESE THIRD ORDER INTERMODULATION PRODUCTS ARE GIVEN BY  0 D"M 0 D"M 0 D"M 0 D"M FF F F     
 4(% 
 The clutter-to-noise ratio represents the mean value of this process over time.  Figure 4.15 assumes a pencil-beam antenna pattern and a constant-gamma model for  clutter reflectivity.46 The antenna beam is pointed at the ground corresponding to the  range of the target. At longer ranges (small look-down angles), clutter decreases with  increasing radar altitude since range folding is less severe owing to less of the main  beam intersecting the ground. 
 This difference  in frequency rnay be used to generate an error signal in a servomechanism which rotates the  antennas until tlie doppler frequencies are equal, indicating that the axis of the antennas is  aligned with tile ground track of the aircraft. The angular displacement of the antenna from  tlie aircraft heading is the drift angle, and the magnitude of the doppler is a measure of tlie  speed along the ground track.  Ttie use of the two rearward beams in conjunction with the two forward beams results in  considerable improvement in accuracy. 
 SOLUTION METHODS  ON THE OTHER HAND  DO  NOT SUFFER FROM PROBLEMS OF SLOW CONVERGENCE BUT  IN GENERAL  REQUIRE COMPONENTS OF SUCH  HIGH ACCURACY AND WIDE DYNAMIC RANGE THAT THEY CAN ONLY BE REALIZED BY DIGITAL MEANS /F COURSE  CLOSED 
 FREQUENCY PULSE 
 Both beams have the same amplitude (voltage) distri- bution F(JC) but differently inclined linear phased fronts. The total aperture exci- tation with both beams is F(JC,I|I) = F(x)ej2^(xla} + F(x)ej2^(xla} = 2F(x) cos (i|i, - i|i2) - ej(^ + ^}(x/a}L a\ That is, the aperture amplitude distribution required for two separate beams var- ies cosinusoidally, and the phase distribution is linear and has the average incli- nation. FIG. 
 120-124, Oct. 25-28, 1977.  63. 
 The whole network is trained purely supervised using SGD with a minibatch size [ 37] of 64 examples, combined with a weight decay parameter of 0.00000001. We rotated images in every 3 degrees for data augmentation. In this paper, the learning rate is initially 0.001 and is reduced by a factor of 0.1 after 100 epochs.3.3. 
 THERADAR EQUATION 19 11(1),TheJ-t1Bhandwidth isdefinedastheseparation inhertzhetween thepointsonthe frequency-response characteristic whcrcthcresponsc isreduced to0.707(3dB)fromitsmaxi­ mUIllvaluc.Thc3-dBhandwidth iswidelylIscd.sinceitiseasytomeasure. Themeasurement ofnoisebandwidth. however. 
 AES–36, no. 4, pp. 1167–1178,  October 2000. 
 This assumption is made to simplify the  coniputations. One of thr: most accurate methods for obtaining the atmospheric profile of  tlie index of refraction is with an airborne microwave refract~meter.~~'~' In one version,39 two  precision microwave transmission cavities are employed, one of which is open to collect a  saniple of the atmospliere. The other is hermetically sealed and acts as a reference. 
 69] IiARLY AIRCRAFT-WARNING RADAR 175 suited forusewith aspiral scan. Arangesweep moves frornthe center ofthetube inadirection corresponding totheprojection oftheantenna beam onaplane perpendicular totheaxis ofscanning (Fig. 6l2c). 
 Thereisanother factorwhichreducesthe right-hand sideofEqs.(14.10)or(14.11b) when opticalprocessing orsimilarprocessing isused.Aswillbeexplained later,thisincreases the right-hand sideofEq.(14.8)by2sothatEq.(14.10)becomes Rcu< _ ()CI-4(1 Similarly, theright-hand sideofEq.(l4.11h) isalsoreduced byafactorof2. Whenasynthetic-aperture radarimagesthegroundfromanelevated platform, theunam­ biguous rangecancorrespond tothedistance between theforward edgeandthefaredgeofthe regiontohemapped. Thisrequires thattheelevation beamwidth betailored toilluminate only theswathS,..thatistobeimagedbyl.heradar.TheswathSwisoftenmuchsmallerthanthe maximulll rangesothattheprfcanbeincreased toallowtheumambiguous rangeRuto encompass filedistance S...cosl/J,wherel/Jisthegrazing angle.Equation (14.12)becomes Sw c-<._--- ()CI-41'cosl/J(14.13) Equation 14.llhwouldalsobemodified accordingly. 
 From Figure 17.15, we have  | || ( )|cos sin( )δλ δ φ ψ π ψ γhR nL=+∆ 2   (antennas separated horizontally) (17.59) In either geometry, since both channels are noisy, the expected accuracy in the  phase difference (1-sigma) is given by Levanon17:  δ φ( )∆ =12 SNR (17.60) where SNR = signal-to-noise ratio (see Section 17.6). Thus, the theoretical accuracy  for terrain altitude measurement is Vertical antenna separation (no banking) :  δλ πhR nL= 2SNR (17.61) FIGURE 17.15  InSAR—-horizontal antenna separation: As long as the two  apertures do not both lie on the same line of sight to the target area, an estimate of  terrain height may be made, by comparing the phases of echoes received by the two  apertures. ( Courtesy of SciTech Publishing, Inc .) ch17.indd   32 12/17/07   6:50:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The zero reference for all rangemeasurementsmustbetheleadingedgeofthetransmittedpulseasitappearsonthe indicator. Inasmuch as part of the transmitted pulse leaks directly into thereceiverwithoutgoingtotheantenna,afixederrorresultsfromthetimerequiredforr-fenergytogouptotheantennaandreturntothereceiver.Thiserrorcauses the indicated ranges to be greater than their true values. A device called a trigger delay circuit is used to eliminate the ﬁxed error. 
 AR is a technique that can forecast the future values on the basis of past values of a time series data, which has well been used in ISAR imaging [ 22]. In this section, we will introduce the AR technique into the DBS imaging. Firstly, the spatial continuity model of the echoed signal should be constructed. 
 BASED 3!2S UNLESS EXTREMELY FINE RESOLU 
 The radiating elements  might b ~ipoles pen-ended waveguides, slots cut in waveguide, or any other type of antenna.  The inherent flexibility offered by the phased-array antenna in steering the beam by means of  electronic control is what has made it of interest for radar. It has been considered in those  radar applications where it is necessary to shift the beam rapidly rrom one posi1ion in spaci: to  another, or where it is required to obtain information about many targets at a flexible, rapid  data rate. 
 AUXILIARYCHANNEL FIG. 9.16 Scheme of sidelobe-blanking system. (From Ref. 
 SEC. 10.10] LINE-T YPE PULSERS 379 operating conditions aswell aslonger life atKlgher frequencies. Apparently the mercury cathode series gapcanbe designed tofirevery precisely. 
 2After the successful experiments ofBreit and Tuve, theradio-pulse echo technique became the established method forionospheric investigation inallcountries. The step from this technique tothenotion ofusing itforthedetection ofair- craft and ships is,inretrospect, not such agreat one; and various indi- viduals took itindependently and almost simultaneously inAmerica, 1Forthefullest treatment ofradar history available, thereader isreferred tothe official history ofDiv. 14,NDRC, “Radar” byH.E.Guerlac, tobepublished by Little, Brown, &Co., Boston. 
 The big ‘blip’ represents the pulse caused  by the ship’s radar transmission signals. The small echo A is  the response from aircraft A, which is not fully in the beam.  Aircraft B is right in the beam, and causes the deeper ‘blip.’  The ship’s beam can similarly be swung or rotated to scan  the coastline. 
 Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.4  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Available Scattering Information.  Prior to 1972, the lack of coordinated  research programs over the necessary long period resulted in only one really usable  set of measurements, developed at Ohio State  University.2,6 Since that time, exten - sive measurements have been made from trucks and helicopters by the University of  Kansas,8,9 groups in the Netherlands,10,11 and several groups in France.12,13,14 These  measurements concentrated especially on vegetation, with the Kansas measurements  also including some work on snow and extensive work on sea ice. 
 15, pp. 36-46, Sept., 1972; pt. 11, Microwa~~r J., voi. 
 P. Kochanski, M. J. 
 FILTER 3!7 PULSE COMPRESSION DEVICE CAN USE VARIABLE FINGER LENGTHS TO ACHIEVE FREQUENCY WEIGHTING  AND THIS INTERNAL WEIGHTING CAN CORRECT FOR THE &RESNEL AMPLITUDE RIPPLES  IN THE &- SPECTRUM 7ITH THIS CORRECTION  n D" TIME SIDELOBE  LEVELS CAN BE ACHIEVED FOR A LINEAR 
 M. Lake, H. Rungaldier,  and J. 
 7, July 1998.  4. M. 
 COST CIRCUITRY   #OMPONENT ASSEMBLY IS ELIMINATED BECAUSE COMPLEX CIRCUIT  CONFIGURATIONS USING BOTH ACTIVE AND PASSIVE COMPONENTS ARE BATCH PROCESSED ON THE SAME SUBSTRATE.   3/,)$ 
 a.EIdEId- <{ <{ fa 10' 10 Frequency Frequency Frequency (a) (b) (e)(3.6) Figure3.7Spectraofreceived signals.(a)Nodopplershift,norelativetargetmotion;(b)approaching target;(c)receding target. .. Tr~ln~rni ttinq  ~rltenno CW AND FREQUENCY-MODULATED RADAR 79  phose  Receivinq  ontenna  motor  indicator  Figure 3.8 Measurement of doppler direction using synchronous, two-phase motor. 
 247-254, 1963.  78. Saxton, J. 
 1 -j -h :. A FIG.11.30.—Front view ofr-f head, shipborne radar: (a) pulse input; (b) transmitter compartment, search radar; (c) receiver, search radar; (d) ATR mount; (e) AFC mixer; U) radar n,ixer; (o) TR-tube mount; (h) r-f switch for noise source; (i) receiver, height- Iinder radar; (j) duplexer, height-finder radar; (k,l) built-in control and test equipment. illustrates many points ofgood design applicable tohigh-power sets in the 10-cm region whether shipborne ornot. 
 Italy has a series of four COSMO-SkyMed X-band SAR  satellites. The COSMO SARs have multipolarization active phased-array antennas  that support a variety of modes including 1-m SpotSAR, strip map, ScanSAR, and  500-km wide swath. The COSMO bus is based on the design built and flight-proven  for Canada’s RADARSAT-2. 
 8.32. A planar array of conventional design with variable phase  sliifrers is shown situ:lterl below r\ he~iiispllerical lens with fixed phase shifts. The lens, with its  fixed pilase shifts, alters the phase front of the field radiated by the planar array to cause a  change in tlie direction of propagation. 
 HF OVER-THE-HORIZON RADAR  20.636x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 An example will serve to illustrate the use of such plots. Select 1000 nmi as the  range. Then, the frequency is 20.5 MHz (wavelength = 14.6 m and λ2 = 23 dB), noise  power = –182 dB, and R4 + L = 260 dB. 
 J. Porcello, and E. N. 
 SCALE 
 !RRAY 3YSTEMS AND 4ECHNOLOGY    "OSTON -!   53!  /CTOBER n    PP n   5 .ICKEL  h0ERFORMANCE OF CORRECTED ADAPTIVE MONOPULSE ESTIMATION v  )%% 0ROC  VOL     PT &  NO   PP n  &EBRUARY    * 7ORMS  h-ONOPULSE ESTIMATION AND 3,# CONFIGURATIONS v  0ROC OF )%%% 2ADAR #ONF     $ALLAS  48  -AY n    PP n   5 .ICKEL  h/VERVIEW OF GENERALIZED MONOPULSE ESTIMATION v  )%%% !%3 -AGAZINE   VOL     NO   PART  OF   PP n  *UNE    ! &ARINA  ' 'OLINO  AND , 4IMMONERI  h-AXIMUM LIKELIHOOD ESTIMATOR APPROACH FOR THE ESTI 
 , vol. 10,   pp. 457–473, 1953. 
 A repeater can be very effective against an unprepared radar system. Repeater jamming,  however, is generally easier to counter than is noise jamming. Against a properly prepared  radar, repeater jamming can be made to have only minimal effect. 
 TilelargerthevalueoffJ2,themore accurate willbetherangemeasurement. Examples oftime-delay (range)accuracy. Thecomputation of/32foraperfectly rectangular pulseonewithzerorisetimeandzerofalltime-resultsinfJ2=00.Thisimpliesthatthe minimum rmsrangeerrorforaperfectly rectangular pulseiszeroandthattherangemeasure­ mentcanbemadewithnoerror.Inpractice, however, pulsesarenotperfectly rectangular sinceazerorisetimeorazerofalltimerequires aninfinitebandwidth. 
 ERED BY THE MULTIBEAM ANTENNA )T USES AN IDENTICAL LEAPFROG SEQUENCE "OTH CONCEPTS RELAX THE FRACTIONAL BEAM SCAN REQUIREMENTS BY EITHER SAMPLING OR STEPPING THE BEAMS IN UNITS OF A BEAMWIDTH 3INCE THEY BOTH PROCESS RETURNS ACROSS TWO BEAMWIDTHS BEFORE  SWITCHING  THE BEAM DWELL TIME  4 B IS APPROXIMATELY  $P2 M 22  C AND THE STEPPING RATE  IS 4B 
 The integrating range in elevation is [−92 m, 92 m ]. Moreover, from (17) and (19), the ﬁrst to the 10th azimuth sidelobes will be suppressed after incoherent addition. T able 1. 
 Ê*," 
 The scattering coefficient is determined by applying _ Pt\2 p G2^dA Pr = (4^J ~R*~ Illuminated area The integration is over whatever area is illuminated significantly, including the regions hit by the minor lobes. The usual assumption is that a° is constant over the illuminated area, so that Pt\2v° rG2dA Pr = -^ ^~T (12'17>(4ir)3 J R4 Illuminated area This assumption would be true only if the antenna confined the radiated energy to a very small spread of angles and to a fairly homogeneous region. The resulting expression is „,—^^_Pt\2 J (Gt2/R4)dA Illuminated area Note that only the ratio of transmitted to received power is required, and so the technique of Fig. 
 J. Appl. Remote Sens. 
 Nathanson, F. E.: Adaptive Circular Polarization, IEEE 1975 International Radar Con./i.•r.:11c.:, A pr.  21-23, 1975, pp. 
 BEAM SIDE 
 The r-ffield atthis point tends tospeed Up theelectron. Asitspeeds up,the radius ofcurvature ofitspath isdecreased, and itwill move along apath corresponding tothe solid line and strike the cathode with appreciable energy. This electron isthus removed from thespace charge, and plays nofurther role intheprocess except perhaps toproduce afew secondary electrons from the cathode. 
 Figure1111showsanexample ofthefrequency dependence ofland clutterforaparticular grazing angle.3?Clutter fromurbanareasinthesemeasurements is independent offrequency; ruralterrainshowsnofrequency dependence fromLtoXband;. 492 INTRODUCTION TO RADAR SYSTEMS  N J, resident101  Arizona desert  Delaware Bay /  Lo In  9 -40 0  -50  - 60  Figure 13.9 Median values of a0 for various terrain: (a) X band, vertical polarization, (h) L band, vertical  polarization, (c) X band, horizontal polarization, (d) L band, horizontal polarization. (From Dulry, rt - -  - -  X" "  I I I I I I Ill I 1 I 1 I III  10  0-  - m 0 -10- -  0  b  0- 9  0 -20 *. 
 For surfaces assumed to be azimuthally isotropic, the  usual approach yields integrals of the form  1232 1 02 cos( c os)( c os) [ ( )] θξ θ ξ ξσ θ ρ ξe Jk dkh − −∫  where  r(ξ) = spatial autocorrelation function of surface heights  q = angle with vertical  sh = standard deviation of surface heights  k = 2p/l  J0 = first-order, first-kind Bessel function The autocorrelation function of height with distance is seldom known for terrain,  although it can be determined on a large scale by analysis of contour maps,60 and it  has been found for some areas by careful contouring at close intervals and subsequent  analysis. Because of lack of knowledge of actual autocorrelations, most theory has  been developed with artificial functions that are chosen more for their integrability  than for their fit with nature; selection among them has been on the basis of which ones  yield the best fit between theoretical and experimental scatter curves. The correlation function first used61 was gaussian:  r(ξ) = e −ξ2/L2 (16.5) where L is the correlation length . 
 reflectarray in a manner analogous to a point-feed illuminating a lens or reflector antenna. The  rti~.c~l/c~l pl~re ,/i~etl uses the pri~lciples of microwave structures to provide efficient power  clivisiorl. It is, ill some respects, a cross between the constrained feed and the space feed. 
 Circular or elliptical “orthogonal” polarized antennas deliver the same information content.  . Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 91     11.3 Complex Radar Cross -Section and RCS M atrix  If [S] and R are known, then σ can be calculated for any arbitrary sender and receiver pol ariza- tion. 
 100. L. B. 
 L. Olsen: Calculation of Radiowave Attenuation Due to Rain at Frequencies  up lo IOOO GHz. Comm1111icatio11s Rl!search Centre (Ottawa, Canada, CRC Rcpt. 
  ULTRAWIDEBAND 3!2 3YSTEM  APPLICATIONS TO FOLIAGE PENETRATION v 0ROCEEDINGS 30)%  VOL   PP n    - & 4OUPS  , "ESSETTE  AND " 4 "INDER  h&OLIAGE PENETRATION DATA COLLECTIONS AND INVESTIGA 
   30!#% 
 4. Moaveni, M. K.: Corrections to "Radio Interference in Helicopter-Borne Pulse Doppler Radars," IEEE Trans., vol. 
 Schafer, Discrete-Time Signal Processing , New York: Prentice Hall  Inc., 1989. 10. W. 
  
 Anderson, F. J. Mei, and J. 
 PULSE VALUES   WHICH GIVES RESULTS ESSENTIALLY IDENTICAL TO 3TEINBERGS RESULTS )F THE INSTABILITIES OCCUR AT SOME KNOWN FREQUENCY  EG  HIGH 
 (7.8)N sin [ir(s/\ sin G] Equation (7.8) describes the fundamental response of a scanned array system. The array factor will have only one single major lobe, and grating-lobe maxima will not occur for -90° < G < +90° as long as IT - lsin G - sin G0I \ TTXor X 1 + lsin G0I which is always true if s/\ < 1A. When scanning is limited, the value of s/\ may be increased, for example, to s/X < 0.53 for scanning to a maximum of 60° or to s/X < 0.59 for scanning to a maximum of ±45°. 
 STC  turns down the gain at close ranges, thereby reducing sidelobe clutter signals. Clutter large  cnoiigh to appear in the sidelobes of a logarithmic receiver might not be suppressed and may  confuse tlie radar display. For this reason STC and logarithmic receivers are sometimes used  together. 
 "  AND  
 The amplitude of the echo signal from a complex target  may vary over wide limits as the aspect changes with respeci to the radar. In addition, the  effective center of radar reflection may also change. Both of these effects-amplitude fluctua­ tions and wandering of the radar center of reflection-as well as the limitation imposed by  receiver noise can limit the tracking accuracy. 
 Maximum directivity is achieved wilh a unirorm apnture  illumination.1 Although it might seem that the higher the aperture efficiency the better, aper­ ture efficiency is seldom a suitable measure of the quality of a radar antenna. Other factors are  usually more important. For instance, the high sidelobes that accompany a uniform illumina­ tion are seldom desired, and the aperture efficiency is usually willingly sacrificed for lower  sidelobes. 
 (Left to  right, above.) Two Gee transmitters are equivalent to two  stones dropped simultaneously into water. The white line  illustrates ripples at a point equidistant from the centres of  splashes. At points mot equidistant from two wave sources the  difference in arrival-time of waves or ‘ripples’ indicates the  position on a series of hyperbolic lines. 
 Any use is subject to the Terms of Use as given at the website. The Radar Transmitter. 10.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 10.3 MAGNETRON Unlike linear-beam tubes that are normally operated as amplifiers, the magnetron  is an oscillator. As example of a commonly used early magnetron was the 5J26, an  L-band tube that was mechanically tunable from 1250 to1350 MHz. 
 Mechanically actuated phase shifters are, of course, not capable of being actuated as  rapidly as electronic devices, nor are they as flexible in being able to select any random value of  phase. It is possible, however, with several electromechanical devices to scan a beam over its  coverage at rates as fast as 10 times per second (0.1 s switching time), which is sufficiently rapid  for many applications.  A change in frequency of an electromagnetic signal propagating along a transmission line  produces a change in phase, as was indicated by Eq. 
 The basic difference between the two is that the  coordinate system moves with the radar in the doppler description, while in the synthetic­ aperture model the coordinate system is fixed to the ground.9  Consider the geometry of Fig. 14.1 in which an aircraft with a sidelooking SAR travels at  a velocity v. (The effect of the elevation angle is neglected in this simple analysis but must be  included in more precise considerations.) When a point scatterer just enters the forward edge  of the beam, it has a doppler frequency 2(v/tl) cos (08/2). 
 VI, discussed in chapter 4. It can be seen that the ASV Mk. III antenna pattern would have produced an unwanted variation in sensitivity of about 20 dB, taking intoaccount the two-way passage of signals through the antenna, for depression angles in Figure 3.9. 
 PERIPHERY TO BASE 
 LOWED BY A DISCUSSION OF ITS VARIOUS COMPONENTS SUCH AS TRACK INITIATION  CORRELATION LOGIC  TRACKING FILTER  AND MANEUVER 
 Any use is subject to the Terms of Use as given at the website. Ground Echo.  GROUND ECHO  16.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 while illuminating it, the look angle changes, and this changes the relative distances to  different parts of the surface; the result is that relative phase shift is changed. This is the  same kind of relative-phase-shift change with direction that is present for an antenna  array and results in the antenna pattern. 
 (1 1.27)] is  Substituting the inequality of Eq. (1 1.34) in the above gives  his states that the time delay and the frequency may be simrtltaneously measured to as small a  Iteoreticc~l error as orle desires by desigr~irig the radar to yield a suficiently large ratio of signal  $rtc>rqjo (E) to rtoise power per /~ertz (No), or $)r $xed E/No, to select a rndor waveforrtt whic/t  restrlts ir~ a large valrte oflla. Large pa products require waveforms long in duration and of  wide baridwidth. 
 STRUCT THE DOWNCONVERTED FREQUENCIES TO RECOVER A TIME 
 The bandwidth of the video signal is Bv = BIF/2  However, for this simplicity the phase information is destroyed if the Radar signal was cohe r- ent before. For coherent systems therefore the I/Q detector, shown in Figure 6.12, is available  (see section 7.1.2).       . 
 This illustrates the compromise that must bemade between efficiency and frequency stability. Magnetrons are usually designed with anoutput coupling such that the center ofthe Rieke ISeeTechnzque ojMicrowave Measurements, Vol. 11,Radiation Laboratory Scrim, Sec.25;seealso Sec. 
 The multifunctional AESA radar in the F/A-18E/F fighter is  shown with a protective cover over the array in Figure 5.1. The AESA is shaped and  canted upward to aid in some modes and to minimize reflections to enemy radars.8Chapter 5 ch05.indd   1 12/17/07   1:26:20 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 J. marshland  Delaware Bay  Grazing angle  (b) J  30° 50° 90°  Figure 13.9 Median values of cr0 for various terrain: (a) X band, vertical polarization, (b) L band, vertical  polarization, (c) X band, horizontal polarization, (J) L band, horizontal polarization. (From Dalt!}\ i:t  a/.:n) . 
 VI. The values in table 7.2are 22 nmi and 32 nmi which are quite consistent, given the uncertainties of the trial conditions and radar sensitivities. The measured detection range for ASV Mk.VII was worse than that for ASV Mk. 
 The loss of the range information and the collapsing loss may be eliminated by first  quantizing the range (time) into small intervals. This process is called range gating. The width  of the range gates depends upon the range accuracy desire! and the complexity which can be  tolerated, but they are usually of tlie order of the pulse width. 
 The antenna mounts ofsurface- based radars represent 10to40percent ofthetotal weight oftheset. 9.10. R-f Transmission Lines .-The r-fenergy generated atthe transmitter isradiated bytheantenna, and theecho isledback from the same antenna tothemixer. 
 17, p. 28, February, 1974.  32. 
 WAVE GYRODEVICES v  0ROC )%%%   VOL   PP n  -AY    - "LANK ET AL  h$EVELOPMENT AND DEMONSTRATION OF HIGH 
 S SQUAREDDISTRIBUTIONWITH DEGRESSOFPDI.FREEDOM  FOR3WERLING)))TARGETCHI 
 The noise temperature or noise figure of the radar receiver has been reduced  to the point that it no longer represents a dominant influence in choosing between  available alternatives. It is a paradox that a noise parameter is usually the first char - acteristic specified for a radar receiver, yet few radars employ the lowest-noise  receiver available because such a choice represents too great a sacrifice in other  performance parameters. Cost is rarely a consideration in rejecting a lower-noise alternative. 
 A two-dimensional parallel-fed array of MN  elements requires M + N -2 separate control signals. The two-dimensional series-fed array  requires but two control signals.  8.3 PHASE SHIFTERS  The difference in phase <P experienced by an electromagnetic wave of frequency f propagating  with a velocity r through a transmission line of length I is  <P = 2rrf 1/v (8. 
 The off-nadir angle of PALSAR-2 in this table is 30.8 degree. InstrumentCenter LatitudeCenter LongitudeCenter Observation Time (UTC: Y/M/D HH/MM)Piercing LatitudePiercing Longitude PALSAR 65.193 −148.439 2014/08/29 22/24 64.603 −144.362 Poker Flat ISR 65.130 −147.471 2014/08/29 22/20 65.130 −147.471 EIELSON station64.660 −147.070 2014/08/29 22/15 64.660 −147.070 205. Sensors 2019 ,19, 516 Figure 2. 
 PLEX THAN THAT SHOWN IN &IGURE  FOR HIGHER GRAZING ANGLES AND WIDER PULSES &ROM THE CHARACTER OF THE DATA  4RIZNA INTERPRETS THESE THREE 
 r-~storef-tractor~ de'~ctorholdconverter • I Coho Mognitude DIA To $(12+02)112--converler--.. display LlI PhoseSample AID Digital Sub-'- f-andf.-canverler storef-Iractor-detectorhold O.orQuadrature, channel Figure4.21Blockdiagram ofasimpledigitalMTIsignalprocessor.. 120 INTRODUCTION TO RADAR SYSTEMS  words are stored in a digital memory for one pulse repetition period and are then stlbtracted  from the digital words of the next sweep. 
 The surface-reflected signal is small so  that the antenna makes small oscillations about some mean position. At greater ranges (eleva-  tion angles less than about 0.8 beamwidth), where the an'tenna main beam illuminates the  surface, the interference between the direct and the reflected signals can result in large errors in  elevation angle. The angular excursions can be up (into the air) or down (into the ground). 
 Some  method must be used to improve angle accuracy for weapon delivery. An example pro - cessing diagram for GMT weapon delivery is shown in Figure 5.38. In this case, three  different classes of target or missile are tracked. 
 Following thefirstsidelobe areaseriesofminorlobes whichdecrease inintensity withincreasing angulardistance fromthemainlobe.Inthevicinity ofbroadside (inthisexample 100to115°),spillover radiation fromthefeedcausesthesidelobe leveltorise.Thisisduetoenergyradiated fromthefeedwhichisnotintercepted bythe reflector. Theradiation patternalsohasapronounced lobeinthebackward direction (180°) duetodiffraction effectsofthereflector andtodirectleakage through themeshreflector surface. c.2 :2 "0 E-30 Q> :> +­o 4U 0::-40 20406080100120 Degreesoffaxis140160180 Figure7.1Radiation patternforaparticular paraboloid reflectorantennaillustrating themainbeamand thesideloberadiation. 
 When the target phase coincides with the clutter phase, the targets are suppressed. In regions that are shadowed by hills or mountains, the targets are not detected. Side-looking radars can produce a large number of pulses, thus increasing ra- dar sensitivity. 
 The 50 cm radar appeared to offer no detection range advantage over metric ASV. However, its antennas offered far less drag and it may have been less susceptible to detection byGerman search receivers, at least in the short term. For these reasons, development of a 50 cm ASV radar continued, together with the 10 cm equipment. 
 ERENCE TO THE FUNDAMENTAL GAIN LIMIT AN APERTURE OF AREA  ! 4HIS LIMIT  APPLICABLE TO  APERTURE ANTENNAS OF SUFFICIENT ELECTRICAL SIZE APPROXIMATELY  SQUARE WAVELENGTHS OR GREATER   IS THE SO 
 Overland navigation by thetraditional dead-reckoning procedure can bebased upon determina- tions ofground speed and drift angle made bytheradar operator through measurements ofthemotion ofground targets, while theposition ofthe N FIG.334.-Boston, Mass. Detailed resolution ofland-water boundaries permits direct comparison with conventional maps. Wavelength =1,25cm,0.8°beam, altitude 4000 ft, ~adi”s 5na”tiral rni. 
 The largest bandwidth is 1/ τ.  At the receiver the signals run th rough a series of  digital delay lines with a run -time delay τ. The signal is sampled after each delay gate and is  then fed into a summing unit. 
 24.11 Plasma- (critical-) frequency contours are given as a function of time of day for July; SSN = 50, latitude = 37.550N, and longitude = 60.560W. Local Time GMT Time FIG. 24.12 Plasma-frequency contours are given as a function of time of day for January. 
 To determine the mean-squared-sidelobe level (MSSL), it is necessary to compare  this energy with the peak of the pattern of an array of N elements so that the mean- squared-sidelobe level is  MSSL =−σ η σT a TN2 21( ) (13.22) Note that in the denominator of this expression the gain due to the array factor  N is reduced by the aperture efficiency ha and by the error power lost from the main  beam ( )12−σT. As an example, consider an array of 5000 elements with an aperture  efficiency of 70%, sa = 0.1 v/v, and sf = 0.1 rad. Then σT2 2 20 1 0 1 0 02 = + = ( .) ( . 
 The envelope has a  fluctuating appearance caused by the random nature of noise. If a large signal is present such  as at A in Fig. 2.1, it is greater than the surrounding noise peaks and can be recognized on the  basis of its amplitude. 
 LENS REFLECTOR IS BEST BECAUSE IT HAS A LARGE CROSS SECTION FOR ITS VOLUME AND HAS A VERY WIDE PATTERN SO THAT ALIGNMENT IS NOT CRITICAL ,UNEBURG 
 low, of the order of several degrees or less, a0 decreases very  rapidly with decreasing angle. This is called the interference region since the direct wave and i . m  0  -10  --20  ITJ  -~~ ()  b -30  40  50  -60  -70 X ANDL  iVERT.ANDH7  X(VF.RT POL)  10 L(HOR. 
 Ifan average istaken, better results can beobtained. 6.13. Homing.’-The useofairborne radar toguide anaircraft toits target was extremely important during the Ivar. 
 SURVEILLANCE RADARS  AND ALL MILITARY AIRBORNE FIGHTER RADARS TAKE ADVANTAGE OF THE DOPPLER EFFECT 9ET IN 77))  NONE OF THESE PULSE RADAR APPLICATIONS USED DOPPLER 4HE #7 CONTINUOUS WAVE     RADAR ALSO EMPLOYS THE DOPPLER EFFECT FOR DETECTING MOVING TARGETS  BUT #7 RADAR FOR THIS PURPOSE IS NOT AS POPULAR AS IT ONCE WAS 4HE (& /4( RADAR #HAPTER   COULD NOT DO ITS JOB OF DETECTING MOVING TARGETS IN THE PRESENCE OF LARGE CLUTTER ECHOES FROM THE EARTHS SURFACE WITHOUT THE USE OF DOPPLER !NOTHER SIGNIFICANT APPLICATION OF RADAR  THAT DEPENDS ON THE DOPPLER SHIFT IS OBSER 
 They differ primarily in their decay times and persistence. The properties of some of the  nhosphors which have been used in radar CRTs are listed in Table 9.1. The degree of image  RECEIVERS, DISPLAYS, ANDDUPLEXERS 355 E-scope. 
  AND @      THE CLUTTER MAP LOSS IS  ,#-    D" SINCE   X    AND ,EFF    FOR THIS CASE !LSO SHOWN IN &IGURE  IS THE CURVE FOR THE CONVEN 
 Burns, and E. M. Turner: High-Power Constant-Index Lens  Antennas, IEEE Trans .. 
 A. Farina, C. H. 
 20, 1975.  72. Hsiao, J. 
  
 Beamshape loss is used primarily in search detection range performance  calculations. RF Receive Loss.  This loss is similar to RF Transmit Loss except it accounts for  ohmic losses from the antenna face to the first low-noise amplifier. 
 Bean, B. R., and E. J. 
 When the traffic is so dense that operators cannot maintain pace  with the information available from the radar, the target trajectory data may be processed  automatically in a digital computer. The availability of small, inexpensive minicomputers has  made it practical to obtain target tracks. not just target detections, from a surveillance radar. 
 Note that this definition does not involve any dissipative losses in the antenna but only the concentration of radiated power. Gain (power gain) does involve antenna losses and is defined in terms of power accepted by the antenna at its input port P0 rather than radiated power P Thus gain is given by _ maximum power density _ /?max total power accepted/4ir R2 /V4ir ^2 For realistic (nonideal) antennas, the power radiated Pt is equal to the power ac- cepted P0 times the radiation efficiency factor TQ of the antenna: Pt = Vo (6.4) As an example, if a typical antenna has 1.0 dB dissipative losses, T] = 0.79, and it will radiate 79 percent of its input power. The rest, (1 - TI) or 21 percent, is con- verted into heat. 
 2Overview • Introduction • Radar functions• Antennas basics• Radar range equation• System parameters• Electromagnetic waves• Scattering mechanisms• Radar cross section and stealth• Sample radar systems. 3•Bistatic : the transmit and receive antennas  are at different locations as  viewed from the target (e.g., ground transmitter and airborne receiver). • Monostatic : the transmitter and receiver are colocated as viewed from  the target (i.e., the same antenna is used to transmit and receive). 
 An example of the CW radar principle is the radio proximity  (VT) fuze, used with great success during World War I1 for the fuzing of artillery projectiles. It  may seem strange that the radio proximity fuze should be classified as a radar, but it fulfills the  same basic function of a radar, which is the detection and location of reflecting objects by  " radio " rn~ans.~.~  isolation between transmitter and receiver. A single antenna serves the purpose of transmission  and reception in the simple CW radar described above. 
 POLARIZATION SPECTRA TO LIE AT A HIGHER FREQUENCY IS LIKELY DUE TO THE PREFERENTIAL SOURCE OF ( 
 102 et seq , January 1999.  8. S. 
 HORN FEED. °n  2!$!2 (!.$"//+  4HE USE OF SMALLER TOP AND BOTTOM HORNS IS A SIMPLER METHOD OF CONCENTRATING THE   % 
 The most common requirement is that the elevation beamMETALWALLS PARABOLICREFLECTOR FEED METALFLANGESRELATIVE POWER ONE WAY IdB) . provide coverage to a constant altitude. If secondary effects are ignored and if the transmit and receive beams are identical, this can be obtained with a power radiation pattern proportional to csc26, where 6 is the elevation angle.2-19 In practice, this well-known cosecant-squared pattern has been supplanted by similar but more specific shapes that fit the earth's curvature and account for sensitivity time control (STC). 
 The use of higher transmission frequencies for tracking radars generally make them  less susceptible to noise jamming than surveillance radars. In addition, tactical track - ing radars may track the noise jammer in angle. Tracking a noise jammer in angle from  two spatially separated radars provides enough information to locate a jammer with  sufficient accuracy. 
 ● The invention and development of the klystron and TWT amplifier tubes that pro - vided high power with good stability.Installation (first letter)Type of Equipment    (second letter) Purpose (third letter) A. Piloted aircraft L. Countermeasures B. 
 ING THE UNDERLYING WEATHER SIGNAL UNPERTURBED  4HUS  WHEN THE GAUSSIAN ASSUMPTIONS  APPLY  THE REMAINING WEATHER SIGNAL SPECTRUM PROVIDES AN UNBIASED ESTIMATOR FOR ALL THE WEATHER PARAMETER SPECTRUM MOMENT ESTIMATES 4YPICAL 7EATHER 2ADAR $ESIGNS  4HERE IS NO UNIVERSAL WEATHER RADAR SYSTEM  DESIGN THAT CAN SERVE ALL PURPOSES !IRBORNE WEATHER RADARS ARE CONSTRAINED BY SIZE AND WEIGHT LIMITATIONS 'ROUND 
 CHAPTER 6 THE GATHERING AND PRESENTATION OF IUDAR DATA BYL.N.RIDENOUR, L.J.HAWORTH, B.V.BOWDEN, E.C.POLLARD 6.1. Influence ofOperational Requirements. I—The purpose ofany radar system istopresent information onthepositions oftargets within the volume ofspace itsurveys. 
 Adetailed treatment offurther systems beyond these two would be ofquestionable value, since changing requirements may soon make obsolete allbut themore general, basic developments ofthepast. Radi- cally new requirements will bemet only byradically new developments, and tobefirmly bound bypast experience would stifle progress. Ingen- ious technical men with good facilities, free intheir thinking, working in close touch with using organizations, fully informed onoperational problems and planning—these aretheimportant requirements forfuture advances. 
 A coarse indication of height sometimes can be obtained hy recognizing the  fading of the echo signal as an aircraft target flies through the multipath lobes of the antenna  pattern. Measuring the range at which the target is first seen on the bottom lohc, or the range  where it disappears because of the first null of the lobing pattern, can be related to the target  height. This eITect is more applicable at the lower microwave frequencies and for radars sited  over water. 
 THE 
 B.: " Microwave Ferrites," John Wiley and Sons, New York, 1961.  30. Ince, W. 
 R.W.Bogle.andD. D.Crombie: SeaBackscalter atHF:Interpreta­ tionandUtilization oftheEcho.Proc.IEEE.vol.62.pp.673-680. June.1974. 
 INDEPENDENT TIME 
 vol. 25, pp. 1352--1356, November, 1954. 
 4RANSMIT "ANDWIDTH 2ATIO 
 27. W. W. 
 The subclutter visibility (SCV) of a radar system is a measure of its ability to detect moving-target signals superimposed on clutter signals. A radar with 20 dB SCV can detect an aircraft flying over clutter whose signal return is 100 times stronger. The IEEE Dictionary™ defines the subclutter visibility as "the ratio by which the target echo power may be weaker than the coincident clutter echo power and still be detected with specified detection and false alarm probabilities. 
 Spillover radiation from the feed,  however, can result in higher sidelobes than from an array with a conventional constrained  feed. The space-fed array can readily generate a cluster of multiple beams, as for  non no pulse  angle measurement, by use of multiple horns or a multimode feed, rather than with a com-  plicated feed network as in the conventional array.  There are two sets of radiators in the lens array requiring matching (the front and the  back), thus increasing the matching problem and the potential for lower efficiency. 
 102. W. D. 
 To correct this situation, automatic detection and tracking (ADT) sys- tems were attached to many radars. As digital processing increases in speed and hardware decreases in cost and size, ADT systems will become associated with almost all but the simplest radars. In this chapter, automatic detection, automatic tracking, and sensor integra- tion systems for air surveillance radar will be discussed. 
 LOSS SPACERS ARE FRAGILE  ITS  
 [ CrossRef ] 11. Donoho, D. Compressed Sensing. 
 Granatstein, and J. Silverstein: Prospects for High Power Millimetcr Radar  Sources and Componen_ts.; IEEE EASCON-77 Record. pp. 
 This problem can be minimized by using limiting. A minor disadvan- tage is that the last n pulses for each range cell must be saved, resulting in a large storage requirement when a large number of pulses are integrated. However, be- cause of the availability of large memories of reduced size and cost, this is a mi- nor problem. 
 If the trajectory  of the target is known from the measurement of the target track, it is possible to infer the  aspect of the radar projection. A radar should not be expected to provide the same target  details as are seen visually. An electromagnetic sensor, whether the eye or a radar, responds to  scattering from those details of the target which are comparable to the wavelength of observa­ tion. 
 A survey carried out during January, February and March 1945 showed that ASV Mks. V and X were signi ﬁcantly more reliable than the various ASV Mks. III and VI. 
 ASV Mk. VII would have used a similar antenna aperture, although the elevation beam pattern is not known. The change in wavelength from 9.1 cm to 3.2 cm would have reduced the azimuth and elevation beamwidths. 
 The radiation pattern is equal to the normalized square of the amplitude, or  G (O) = J~_a_l~ = sin2 [Nrr(d/J) sin OJ  a N2 N2 sin2 [rr(d/J) sin OJ (8.4)  If the spacink' between antenna elements is J/2 and if the sine in the denominator of Eq. (8.4)  is replaced by its argument, the half-power beamwidth is approximately equal to  102 OB= ----­N (8.5)  The first side lobe, for N sufficiently large, is 13.2 dB below the main beam. The pattern of a  uniformly illuminated array with elements spaced ).../2 apart is similar to the pattern produced  hy a continuously illuminated uniform aperture [Eq._ (7.16)]. 
 It is not always convenient, however, to use four-port junctions. Three-port tee  junctions are sometimes used for economic reasons to provide the power splitting, but the  network is not theoretically matched. Internal reflections due to misn~atch in the feed can  appear as spurious sidelobes in the radiation pattern."  Space feeds. 
 MTI systems atpresent reduce theclutter byperhaps 30db-which inmany locations isadequate. But mountainous terrain that does not appear. SEC. 
 The individual faces of the corner reflector may be of arbitrary shape, but the most  common is an isosceles triangle for the trihedral corner; dihedral corners typically  have rectangular faces. The RCS of a corner reflector seen along its axis of symmetry FIGURE 14.7  RCS of a square flat plate 96-in along a side measured at 790 MHz.10 The HH  and HV patterns have been artificially lowered 5 dB for clarity. ( Courtesy of S. 
        WHERE I AND J ARE INTEGERS RANGING FROM  TO - 0 CODES ARE SIMILAR  BUT THE PHASE IS SYMMETRIC WITH THE FOLLOWING CHARACTERISTIC   FP PIJ -- - I J - J [  ;   =     ]; = 
 Itwas hard tofind room forallthe plotters around the table. They could not plot fast enough. They might disturb one setofplots when they leaned over toplot another aircraft. 
 Strange as it may now seem, in the early days pulse  radar encountered much skepticism. Nevertheless, an effort was started at NRL in the spring  of 1934 to develop a pulse radar. The work received low priority and was carried out prin-  cipally by R. 
 A DeCesare, M. J. Martineaus, R. 
 [ CrossRef ][PubMed ] 19. Qin, X.; Yang, T.; Yang, M.; Zhang, L.; Liao, M. Health diagnosis of major transportation infrastructures in Shanghai metropolis using high-resolution persistent scatterer interferometry. 
 6R WHERE 6R IS THE RADIAL VELOCITY EXPRESSED IN  MS 6R    FOR AN OUT 
 WAY ROCKER SWITCHES ARE TYPICALLY USED 4HE OPERATIONAL AREA OF A RADAR DISPLAY IS NORMALLY CIRCULAR  ALTHOUGH THIS IS NO  LONGER A MANDATORY REQUIREMENT )T ORIGINATES FROM THE HISTORICAL USE OF CONICAL DISPLAY TUBES BUT IS RETAINED BY MOST MANUFACTURERS AS IT GIVES ADDITIONAL SPACE OUTSIDE OF THE OPERATIONAL AREA FOR THE DISPLAY OF DATA AND MENUS SEE &IGURE   4HE MINIMUM OPERATIONAL DISPLAY AREA IS DEFINED AS A DIAMETER  MM FOR SHIPS LESS THAN  GT  MM FOR SHIPS FROM  TO   GT AND  MM FOR SHIPS ABOVE   GT 4HE MINIMUM RECOMMENDED DISPLAY AREAS FOR SMALL CRAFT RADAR ARE GIVEN IN 4ABLE  4HE COLOR OF RADAR TARGETS AND BACKGROUND IS NOT MANDATED 4HE TARGET TRAILS THAT USED TO BE PROVIDED BY THE DESIGNED 
 Repeater "false echoes" can be unmasked as such hy  utilizing in an unpredictable manner different pulse repetition frequencies, rf frequencies, pulsc  widths, internal pulse modulations, or polarizations. Sidclohe hlankers can prevent repeater  signals from entering the radar via the antenna sidelohes and appcaring on the display in  directions different from that of the jammer. In a tracking radar, circuitry can hc dcviscd to  prevent range-gate stealers from capturing the range gate. 
 With early  H2S technique the map was little more than a skeleton,  showing the main features, towns, rivers, and coastlines  standing out clearly. With later systems it has been  possible to ‘draw’ the map with a narrower beam of  radiation, and thus to give more detail in the picture.  It is not unreasonable to suppose that development along  these lines could produce an H2S-type equipment cap-  able of showing almost as much detail on the ground,  from a height of, say, 2000 feet, as does a television pic-  ture on the 405-line system. 
 Noise Suppression Performance Figure 6shows the results obtained by applying the traditional imaging approach and the proposed approach when there is noise in echo signal, where the noise is 5 dB complex white Gaussian noise. Add the complex white Gaussian noise with SNR ratio of −15 dB to 25 dB in the echo data, repeat Monte-Carlo simulation test for 100 times under every noise level, and calculate MSE estimated on the basis of height. In Figure 6, imaging results show that there is a considerable deviation in estimation of traditional processing approach on height of target scattering point. 
 Let usseehow closely atypical radar system approaches this funda- mental limit. Consider anairborne ground-mapping radar with a1.5° beamwidth and PRF of1800 pps, scanning at15rpm. Suppose that thepulse duration is1psec and that aregion 30miles inradius ismapped onthe indicator screen. 
 Appl. Meteorol.,  vol. 28, pp. 
 1–18. 81. H. 
 Keeler, “Comparison of pulse compression & whitening transform signal pro - cessing,” in 4th European Radar Conf. , Barcelona, 2006, pp. 109–112. 
 1, 1966.  41. Crain, C. 
 17.7.—Phase-ahift data transmission using one c-w subcarrier. transmitter and receiver design. Analternative would betotransmit the pulses onthevideo carrier during those intervals when theecho signals are not useful. 
 VELOCITY MITIGATION VIA 3: PHASE CODING  WITH EXPERIMENTAL 3 
 As rain moves in~o the area, or as propagation conditions result in changing ground­ clutter levels, the clutter map changes accordingly. The values stored in the map are multiplied  by an appropriate constant to establish the threshold for zero-relative-velocity targets. This  eliminates the usual MTI blind speed at zero radial velocity and permits the detection of  crossing ~argets in clutter if the target cross section is sufficiently large. 
 2 DECOMPOSITION WITH 'RAM 
 Once the pulse power output issettled and the appropriate switching tube chosen, 20can bedetermined from one ofthe relations P=I;“ZOorP=V~/ZO. Usually either I,orV,isdefinitely limibed foragiven switch; this indicates the appropriate relation touse incalculating Zo. Itmust beremembered that the voltage across the pulse network (and hence across theswitch) istwice thevoltage delivered toamatched load.. 
 HYPOTHESIS TRACKING FILTERS  WILL BE FOLLOWING SEVERAL HUNDRED '-4S OF INTEREST SIMULTANEOUSLY )N MOST CASES  ALL TARGETS MUST BE TRACKED AND THEN RECOGNIZED ON THE BASIS OF DOPPLER SPECTRUM HELICOPTERS VS WHEELED VEHICLES VS TRACKED VEHICLES VS SCANNING ANTENNAS   RATE OF MEASURED LOCA 
  OR # 
 STATE SWITCH TO OPEN QUICKLY LESS THAN ONE MICROSECOND  WHEN A FAULT IS DETECTED ELIMINATES THE NEED FOR A CROWBAR 4HE ENERGY 
 6“7. Three-dimensional Display s.—In spite ofthefact that theface ofthe cathode-ray istwo-dimensional, two conventionalized three- @B-- 4%.E3c -- .- C 22 A- ~1 -30° 0 +30”—positionof antenna beam (a)Double-dot indicator. (b)Pattern ofspiral scan (.)Radial timebase (RTBJ used with displays indicator. 
 4.6, the tube will not stop when RF drive is removed; the reentrant electrons still carry enough energy that secondary emission from the cathode is maintained, and the tube will oscillate near a band edge or generate broadband noise until the cathode voltage pulse ends. In addition, once operation has been started by RF drive, back bom- bardment heats the cathode, and on following pulses the cathode current may start from thermionic emission even before RF drive is applied. Since this would also produce noise output, it is customary to make the RF drive pulse straddle the modulator voltage pulse to prevent this. 
 3.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 Airborne MTI James K. Day Lockheed Martin Corporation Fred M. Staudaher* Naval Research Laboratory (retired) 3.1 SYSTEMS USING   AIRBORNE MTI TECHNIQUES Airborne search radars were initially developed for the detection of ships by long-range  patrol aircraft. 
 451–460, 1975. 63. S. 
 BAND RADAR CAN ONLY OPERATE WITHIN THE FREQUENCY RANGE FROM  -(Z TO  -(Z  AND EVEN WITHIN THIS RANGE  THERE MAY BE RESTRICTIONS 3OME OF THE INDICATED )45 BANDS ARE RESTRICTED IN THEIR USAGE FOR EXAMPLE  THE  BAND BETWEEN  AND  '(Z IS RESERVED  "AND $ESIGNATION .OMINAL &REQUENCY 2ANGE3PECIFIC &REQUENCY 2ANGES FOR 2ADAR "ASED  ON )45 &REQUENCY !SSIGNMENTS   FOR 2EGION  (&  -(Zn -(Z 6(& n -(Z n -(Z n -(Z 5(& n -(Z n -(Z n -(Z , n '(Z n -(Z 3 n '(Z n '(Z n '(Z # n '(Z n '(Z n '(Z 8 n '(Z n '(Z+ U n '(Z n '(Z n '(Z + n '(Z n '(Z n '(Z +A n '(Z n '(Z 6 n '(Z n '(Z 7 n '(Z n '(Z n '(Z4!",%  )%%% 3TANDARD ,ETTER $ESIGNATIONS FOR 2ADAR 
 L.: Three-dimensional Air Surveillance Radar, Systems Technology. (Plessey Co, Iford.  England). 
 163-170.  65. Pollock, E. 
 ART 7 
 W. L. Patterson, “Advanced refractive effects prediction system,” Space and Naval Warfare  Systems Center TD 3101, January 2000. 
 ENCE LED TO RESULTS THAT OFTEN SHOWED CONSIDERABLE INCONSISTENCY AND SUGGESTED CLUTTER BEHAVIOR THAT WAS SOMETIMES MORE A FUNCTION OF THE VAGARIES OF THE EXPERIMENT THAN OF THE PHYSICS OF THE CLUTTER !S DATA OF INCREASINGLY BETTER QUALITY ACCUMULATED  IT MIGHT HAVE BEEN EXPECTED THAT THE BEHAVIOR OF SEA CLUTTER WOULD BE ESTABLISHED WITH INCREAS 
 INTERVAL RATIO LOOKS LIKE A TARGET AT ONE 
 E. Vivian, E. N. 
 The circuit hasthe marked advantage that the time forthe fhp-flop action isremarkably linear with thebias voltage ofg,,sothat bymeans ofanaccurate poten- tiometer controlling this voltage alinear timing circuit ofrather low precision canbemade. The circuit canbesomewhat improved over that shown inFig. 13”16 bytheaddition ofabiased diode inthegrid circuit of Vztodetermine theprecise limit ofthenegative excursion ofthat grid. 
 On reflection from the surPdct. the vertically  polarized component is attenuated more than the horizontal component, and it experiences a  different phase shift (Fig. 12.3). 
 BASED DUCT 3URFACE 
  AND AZIMUTH ANGLEnDEPENDENT INFLUENCES FROM SURFACE  FEATURES TO INCLUDE TERRAIN ELEVATION  FINITE CONDUCTIVITY  DIELECTRIC GROUND CONSTANTS  AND SCATTERING EFFECTIVENESS FACTORS 4HE TERRAIN ELEVATION DATA MAY BE OBTAINED FROM THE .ATIONAL 'EOSPATIAL 
 The other, and probably more common method for con - ceptual radar system design, is to start with what the new radar has to do, examine the  various approaches available to achieve the desired capability, carefully evaluate each  approach, and then select the one that best meets the needs within the operational and  fiscal constraints imposed. In brief, it might consist of the following steps: ch01.indd   22 11/30/07   4:34:09 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The collapsing loss in this case is equal to the ratio of the integration loss Li  (Sec. 2.6) for n1 + 11 pulses to the integration loss for n pulses, or  For exaniple, assume that 10 signal-plus-noise pulses are integrated along with 30 noise pulses  arid that Pd = 0.90 and rlf = 10'. From Fig. 
 47. Mooney, D. H., and W. 
 ETER MISSIONS SPLIT INTO TWO THEMES  DETERMINED BY THE RELATIVE PRIORITY OF THEIR MEA 
 However, the sense of rotation ofthe vector which represents the field ofthe scattered wave issuch that ifthe scattered wave passes back through the original quarter-wave plate itWN emerge asawave whose polarization isper- pendicular tothat ofthe initial linearly polarized wave (Fig. 3“13). Itwill therefore not enter the antenna which was the source ofthe original linearLy polariaedwwre. 
 Control of the echo characteristics of some targets is of vital tactical impor- tance. There are only two practical ways of doing so: shaping and radar absorb- ers. Shaping is the selection or design of surface profiles so that little or no en- ergy is reflected back toward the radar. 
 6G COS X  AND WOULD BE INDEPENDENT OF RANGE 4HE RATIO OF THE  ACTUAL BORESIGHT VELOCITY TO THE COPLANAR BORESIGHT VELOCITY IS DEFINED AS THE NORMAL 
 8.1 beacons have sometimes been used inproviding communication systems ofamdimentary sort andalso forexercising remote control. Intelligence has been conveyed from theradar toabeacon-carrying vehicle bymodi- fication ofthe repetition rate, the length ofinterrogating pulses, their spacing ingroups, ortheduration oftheintervals ofinterrogation. The replies ofthe beacons have also been modulated insuch ways. 
 34, pp. 528–578, August 1946.  3. 
 F. T. Ulaby, W. 
 Thegainsofthechannels alsomustnotdifferbymorethanspecified amounts. Analternative approach tousingthreeidentical amplifers inthemonopulsereceiver isto usebutoneIFchannel whichamplifies thesumsignalandthetwodilTerence signalsona time-shared basis.17•19Thesumsignalispassedthrough thesingleIFamplifier followed by thetwodilTerence signalsdelayed intimebyasuitable amount. Mostofthegainandgain ELEVATION DIFFERENCE CHANNEL AZIMUTH DIFFERENCE CHANNELELEVATION­ ANGLE ERROR Figure5.9Blockdiagram oftwo-coordinate (azimuth andelevation) amplitude-comparison monopulse tracking radar.. 
 Speed Regulators .... ... Dynamotors .......... 
 ATIONS AND DESIGN DRIVERS  BUT THESE ARE BEYOND THE SCOPE OF THIS CHAPTER    "7 
 rII FIG,12.19 .—AN/APS-lO receiver; top and bottom views. accompanied bythree disadvantages. First, this detector isnot St,rictly linear, adifficulty that isnottooserious since this system isnotintended tobeoperated insituations where interference istobeencountered. 
 4, 1956, pp. 29–32. 23. 
 Generally thetopofthe displaycorresponds tonorth.Thistruebearingdisplayeliminates theblurring ofapersistent screendisplaycausedbythenaturalrandom changes inheadingofthevehicle.Italsoelimin­ atestheconfusion sometimes foundinarelative-bearing displaycausedbytheentiredisplay rotating asthecourseofthevehicleisaltered. Correction ofthedataisalsoneededwithline-of-sight stabilization usingatwo-axis mount.Datastabilization isnotnecessary ifathree-axis mountisused.suchaseorfof Fig.7.31. Ninepossible arrangements formounting antennas areshowninFig.7.31.Theone-axis mountisthesimplest. 
 /6 
 This scheme presumes that the arriving signal wavefronts  are essentially planar or smooth after ionospheric reflection, which is not always  the case.126 • Joint analysis of multiple discrete meteor echoes.127,128 This scheme is appealing but  relies on having enough identifiable discrete echoes. For a 32-element array it may  be generally viable, but less frequently for a 500-element array . • Receiver and plane wave rejection tests applied to injected broadband noise.129  This approach provides useful metrics of calibration performance and relative  performance, but does so only downstream from the receiver inputs, as with  (ii) above. 
 Therearetwofundamental limitstothemaximum effective lengthofthesynthetic aper­ ture.Onelimitisdetermined bythewidthoftheregionilluminated attherangeRbythereal antenna. Thelengthoftheeffective aperture Lecanbenogreaterthanthewidthofthe illuminated regionasgivenbyEq.(14.3).ThusLe;5;ROB'Notethatthemaximum effective lengthvariesdirectlyastherange.Theotherlimitisdetermined bythefarfieldofthesynthetic apalUfc; i.e.,bytheneedtorestricttheaperture sizesothatthephasefrontcanbeconsidered asJplanewave.Whenthiscondition applies,theSARiscalledunfocused. Figure14.2defines themaximum aperture ofanunfocused SARs\1\:hthatthedifference between theminimum andmaximum (two-way) pathsisaquarter wavel~ngtl iFromthisgeometry itcanbederived thattheelTective lengthLeofthesynthesized anteIlllahjRi,sothatthecross-range resolu­ tionforlheunfocused synthetic antenna is (14.5) Figure14.2Geometry oftheunfocused SAR.. 
 MIT AND THE RECEIVE ANTENNA PATTERNS /N TRANSMIT  NULLS CAN BE PLACED IN THE DIRECTION  OF HIGH GROUND CLUTTER TO REDUCE THE CLUTTER POWER REFLECTED BACK TOWARD THE ANTENNA  !CTIVE ARRAYS TYPICALLY HAVE BOTH AMPLITUDE AND PHASE CONTROL AT EACH ELEMENT  WHICH ALLOWS EITHER FULL AMPLITUDE AND PHASE NULLING OR PHASE 
 s, ___ b J~- Focus--- Precision ~ ~ -Fixed Fixedmarkervar!ableVideo--- Trigger delaydelaygenerator andmixerInt. Video111 Switchposition(a) (A)Switching wave (B)Sawtooth (C’)Invertedsawtoolh 1 I 11 1 1 !~uf;;‘r‘t’! 3FPIor5CPI(D)Variabledelay ——— {Ur‘‘Lw /\ ,,,,,””~ \ .- 1A--P-+1 v,.FFFF=71F=44T!4W-J %f!-m”” “’’’’”‘“w(E)Var,ablemarker LWeo (F’)Markers K— —-- Focus IT,‘i--iII ‘~lhF’(A) ’witchingwave1’M t’zL 1 III I I III.%+ -J 11J1!1Centering 4W-A’(B)Sawtooth v, a 14Tofixed1= ~~ s, markergenerator F,<;.I:$42.-Gc,,cr&r>ur,>ose A-SCOSE. .,,,,, ,,.,,,,,,,,, ,$,,,,,,.>,.,),,.,, ,,,,,,,,,,,,,,,.,, ,,,,,,,.,,,,. 
 136. Sensors 2019 ,19, 2921 According to Equations (17)–(19) and the parameters given in Table 1, we can get the h–ΔRmax relationship curve (Figure 4). max /16 R' =O Figure 4. 
 M RESOLUTION IN 3CAN3!2 MODE AT  
 4(% 
 Tlie simple OTi-i radar equation of Eq. (14.22) does not account for the  fact that a surveillance radar must cover a specified angular sector in a specified time. The  radar equation for a microwave surveillance radar was given by Eq. 
 °£n  2!$!2 (!.$"//+  GEAR BACKLASH "ACKLASH MAY ALSO BE REDUCED WITH CONVENTIONAL MOTORS BY DUPLICATE  PARALLEL DRIVES WITH A SMALL RESIDUAL OPPOSING TORQUE WHEN NEAR ZERO ANGLE RATE !MPLIFIER GAIN AND FILTER CHARACTERISTICS AS WELL AS MOTOR TORQUE AND INERTIA DETER 
 NORMAL INTERFERENCE WERE CALCULATED BY 3CHLEHER  AND ARE -       AND  FOR .       AND   RESPECTIVELY "ATCH 0ROCESSOR  4HE BATCH PROCESSOR &IGURE  E  IS VERY USEFUL WHEN A LARGE  NUMBER OF PULSES ARE WITHIN  THE  
 21.4 PROPERTIES OF MATERIALS The determination of the dielectric properties of earth materials remains largely exper - imental. Rocks, soils, and concrete are complex materials composed of many different  minerals in widely varying proportions, and their dielectric parameters may differ  greatly even within materials that are nominally similar. Most earth materials contain  moisture, usually with some measure of salinity. 
 Cochran, B. Moran, and  L. White (eds.), Amsterdam: Elsevier, 2001, pp. 
 I  I  <1> 1.2  VI  C  0 a.  VI  <1> ...  ~ 0.8  ~  C. 
 26. Chellapilla, K.; Puri, S.; Simard, P . High performance convolutional neural networks for document processing. 
 both in the radar's  own band as well as from. outside the band.50 The radar must be designed to reject these  unwanted radiations and to minimize the likelihood of its own transmissions causing trouble  to other users of the spectrum. This is the subject of EMC, or electromagnetic compatibility. 
 72-80, May, 1978.  56. Hallford, B. 
 SCAN BASIS 4HIS IS SO BECAUSE PULSE 
 The radar equation  (2.1 ), with the modifications indicated in this chapter, becomes  -R4 _ . PavGAp 0anE;(11)  max -(4n)2kTo f n(Br)fp(S/N), Ls (2.54) . THE RADAR F.Ql/ATION 63  where R,,, .. 
 HETERODYNE APPARATUS FOR CHANGING THE TIME 
 S., and T. W. R. 
 The mutual coupling between two small  isolated dipoles57 should decrease as 1/ r in the H plane and 1/ r2 in the E plane ( E and  H planes are interchanged for slots). Coupling measurements58 have shown that in the  array environment the rate of decay is slightly greater than predicted above, indicating  that some of the energy is delivered to other elements in the array and may be dis - sipated and reradiated from these elements. The same measurements have shown that  the phase difference of the energy coupled to elements is directly proportional to their  distance from the excited elements, indicative of a surface wave traveling along the  array, leaking energy to each of the elements. 
 727–730, September 1981. 62. R. 
 F  #ONJUGATE OF SIGNAL   DXDT JPF8  F   4IME DOMAIN DIFFERENTIATION   
 CM 3!2   SCATTEROMETER ,UNAR 2ECONNAISSANCE  /RBITER ,2/ 53!  -OON  -INI 
 pp. 151 160, May, 1977.  66. 
 Figure 10.46 shows the basic configuration of a time-expansion stretch pro- cessor for a linear-FM waveform. Let the received waveform be given by em = A rectlr - ^) sin [2ir(/b + /</)(' ~ Tin) + mxin (/ - rin)2 + <|>] \ ^ in/ where rect (XlT) is a unit amplitude pulse of duration T for IAH ^ 772; jin, 7in, and ain are the target time delay, the time pulse length, and the input frequency slope, respectively. The delayed waveform generator output will be eR = 2 rectl t - -H sin [2tt fR (t - TR) + iraR(t - 7R)2 + 4>] \ 1R/ where the constants are the reference waveform equivalent of the received waveform constants. 
 #HU EQUATIONS     %N ( N % N %SIK: D3  r   r r    ¯[      ]u; 99 9       (N % N ( N %SIK9 D3 
 Soc. Am ., vol. 25,   pp. 
 17, pp. 940-971, November, 1946.  10. 
 (This is the opposite of No. 2.)  4. Irotn radar to target via reflection from the surface and return by the samc pat11  (AMB-BMA). 
 Weareinterested, however, in targets such asairplanes and clouds which have non-uniform distributions ofradial speeds, and would like toknow the best values ofthe blind speeds inthese cases. Figure 16.24 shows the distribution ofradial velocities forairplanes whose ground speed can have any value between 100 and 400 mph with equal probability and whose direction offlight israndom. Itishard to choose the best blind speeds from this graph. 
 Microwave J.,vol.20.pp.24and26.March.1977. 98.Skolnik, M.I.:APerspective ofSynthetic Aperture RadarforRemote Sensing, NavalRest?arch Laboratory Memorandum Rept.3783,May,1978,Washington, D.C. 99.Weston, V.H.:TheoryofAbsorbers inScattering, Trans./EEE,vol.AP-IJ.pp.578-584. 
 RIC DETECTORS  AND CLUTTER MAPSHAVE BEEN USED TO REDUCE THE FALSE 
 NOTCH SECTION OF THE -4) IS DETERMINED BY THE REQUIRED IMPROVEMENT FACTOR AND THE SPECTRAL SPREAD OF THE LAND CLUTTER 4YPICALLY  THE FIXED 
 Anoperator can gotothe turret and, bytransferring the usual remote controls toaduplicate setinthe turret, operate the radar and view theechoes orwaveforms onthe scope provided. Auni- versal meter furnishes aquick check onallthe currents mentioned in Sec. 11.11. 
 20  sets of pulses. The final output may be of the form  shown in Fig. 20, but, of course, there are many varieties  of the ‘gating’ device. 
 In order to improve the accuracy of the Doppler parameter estimation, multiple iterations are performed. The ﬂowchart of the azimuth compression combined with the EMAM method in the high-squint SAR imaging algorithm is shown in Figure 4.   (a) (b)  Figure 3. 
          
 #&!2  SUCH AS GREATEST 
 POLARITY !RCHITECTURE  ! LEADING HIGH 
 TRACK  RESOLUTION THAN A CONVENTIONAL ALTIMETER AND AN ORBIT THAT ACCUMULATES DENSE CROSS 
 This is easily explained by the fact that the prob - ability of a significant outage of data is much reduced if two sources are available. With  a more accurate track, tighter association criteria can be used for detections. If the biases cannot be effectively removed, then there may be an advantage to asso - ciating to a single radar track—which by definition is unbiased with respect to itself. 
 !\s mentioned previously the Reggia-Spencer phase shirter is reciprocal but has limita­ tions 5ud1 a5 .slow switching speed. temperature sensitivity, and a not particularly good figure  8,(2)  8, (3)  -B, --------,.,(i)  Figure 8.12 Hysteresis loop showing the  principle of flux drive. where a single  ferrite toroid is excited by discrete  current pulses to produce digital phase­ shirt increments from what is basically  an analog device. 
 Minimum detectable RCS versus range, Pd=0.5,Pfa=10−4, Swerling 1 target; (a) ASV Mk. III, 1000 ft; (b) ASV Mk. III, 2000 ft.Airborne Maritime Surveillance Radar, Volume 1 7-10. 
 Observation of eddy structures in the baltic sea with the use of radiolocation and radiometric satellite data. Izv. Atmos. 
 ON 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.616x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 the form of Figure 20.28 on Earth backscatter echo power. 
 562 Fm.PRIME POWER SLTPPLIES FOR RADAR [SEC. ..... Primary contactor ~~[~__-,,=.,,.,.C..,- ‘,”,. 
 the  pattern is independent of beam direction.  Most of the work on conformal arrays has been with the cylinder. Even though it may be  a relatively simple shape compared to the others mentioned above or to the generalized  non planar surface, the properties of the cylindrical array are not as suitable in general as those  of the planar array. 
 In contrast tospark devices, the hy- drogen thyratron will operate over a very wide range ofanode voltages without readjustment. This char- acteristic isparticularly important forexperimental pulsers, orforany pulser whose probable load isin doubt. Ingeneral, itisdifficult to reduce the voltage across aspark switch bymore than afactor of2 from the nominal design voltage without encountering erratic opera- tion. 
 ThenearriekJisfollowed bytheFresnelregion.IntheFresnel region,raysfromthe radiating aperture totheobservation point(ortarget)arenotparallel andtheantenna radiation pattern isnotconstant withdistance. Littleapplication ismadeoftheFresnelregion inradar.TheIIf'W'fieldandtheF/'(Is/lelreg;o/lhavesometimes beencalledbyantenna engin­ eersther{'(lct;!'C/Icar-fidd regionandtheradiating near-field region,respectively,6 Thefarthest regionfromtheaperture istheFraunhofer, orfar-field, region.IntheFraun­ horerregion,theradiating sourceandtheobservation pointareatasufficiently largedistance fromeachothersothattheraysoriginating fromtheaperture maybeconsidered parallel to oneanother atthetarget(observation point).Radarantennas operate in'theFraunhofer regIon. The"boundary" RFbetween FresnelandFraunhofer regionsisusuallytakentobeeither RF=Dl/J...orthedistance RF=2Dl/l,whereDisthesizeoftheaperture andlisthe wavelength, DandJ...beingmeasured inthesameunits.Atadistance givenbyDZIl,thegainof auniformly illuminated antenna is0.94thatoftheFraunhofer gainatinfinity. 
 The average data rate from space-based SARs in Earth orbit is on the order of  100 Mb/s, (megabits per second) with higher resolution and polarization diversity sys - tems generating several times that. The drivers are the spacecraft velocity ( ∼7.5 km/s),  range resolution, and swath width. Many users would like to have immediate access  to processed data, which leads to the question of onboard processing. 
 2.2.2.2 Antennas The homing antennas were originally simple quarter-wave diploes, later changed to three-quarter wave diploes. These were considered obsolete by late 1943 [ 7] but some systems were still in use and referred to as SRASV (short range ASV). The LRASV homing antennas comprised a single transmitter Yagi array mounted on the nose of the aircraft and two receiving Yagi arrays, one under each wing with their axes pointed at an angle to the centre line of the aircraft. 
 xyz TiT IT Figure 1. The conﬁguration of WASAR. We vectorize Equation ( 1) and express it in a compact form ri=Φi·si+zi, (2) where riis the history data of i-th subaperture, siis the backscattering of i-th subaperture, and ziis the noise, the measurement matrix Φiis shown as Φi=⎡ ⎢⎢⎢⎢⎢⎢⎢⎣φi(1, 1) φi(1, 2) ... 
 Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 22.4  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 Detection Performance.  In-the-clear detection requirements for such radars are  not particularly demanding. 
 the90°phaseshiftthatresultsbetween thesignalsinports2and3willproduce abeam oriented inadirection 30°totherightofthearraynormal. AsignalinportNo.4rl:sultsill 0.70lv(st 0.101V/900 CD CD lV1St RighIbeam0.101vdD" 0.101V&:- G) o 1V& LeftbeamFigure8.273-dBdirectional couplergenerating twobeams fromatwo-element array.. ;I pliasc clist~il~trtioti tlii~t produccs a I~ca~ri 30" to tlic left of tlic array rior~nal. 
 It is introduced directly into the receiver via a cable or other direct connection.  .  A (6) Figure 3.10 Frequency-time relation-  U C w I ships in FM-CW radar. 
 PURPOSE DEPLOYMENTS 4HE PRINCIPAL VIRTUE OF (&372 AS AN OCEAN SURVEILLANCE RADAR LIES IN ITS ABILITY TO  DETECT SMALL SURFACE VESSELS AND LOW 
 3. Selridge, H.: Proximity Fuzes for Artillery, Electronics, vol. 19, pp. 
 RELATED DATA  SUCH AS DESTINATION PORT AND %4!  DEPTH UNDER KEEL  AND HAZARDOUS CARGO TYPE 4HE DYNAMIC DATA IS BROADCAST AT A RATE CONSISTENT WITH THE VESSELS VELOCITY AND WHETHER IT IS CHANG 
 Since the probability of a false alarm is the probability that noise will  cross the threshold, Eq. (2.24) gives the probability of a false alarm, denoted Pra.  The average time interval between crossings of the threshold by noise alone is defined as  the false-alarm time Tra,  where Ji is the time between crossings of the threshold Vr by the noise envelope, when the  slope of the crossing is positive. 
 Aydin, T. A. Seliga, and V . 
 Cosmos 1500 Side-Looking Radar  ......  22.17  22.4 Technolog y  .............................................................  22.17  Antennas  ........................................................... 
 Hanbury-Brown were two of the  British scientists prominent in the development of air-  borne radar to locate submarines.  All this successful development is now, of course, only  war history, and is apt to be lost in the great accumula-  g Heme of recends. of international strife. 
 Syst. 1991 ,27, 194–207. [ CrossRef ] 7. 
 near by. Fixed features of the landscape—tall buildings,  . 42 HOW RADAR WORKS  hills, headlands, and masses of trees—all give reflections  of the radio-energy pulses. 
 of Rem. Sens. , vol. 
 Thus detection may be accomplished by establishing a threshold at the  oulpu! of a receiver which computes the JikeJihood ratio. The selection of the proper threshold  level will depend upon the statistical <letection criterion used and by the probabilities of error  desired and their relative importance.  The likelihood ratio is primarily useful in the analysis of the statistical-detection problem. 
  
 The corresponding  frequency is denoted fo, and the direction of beam pointing becomes  If the beam is steered over the limits + 0, the wavelength excursion AA is given by  1 AA sin 8, = 2d A.  Thus there is a tradeoff between the wavelength excursion and the length of line connecting the  elements. Figure 8.15 is a plot of the beam direction as a function of the frequency for various  values of thef'wrap-up fador Ud, as given by Eq. 
 Itsscan covers therange ofelevation angles from lYto15°. Elevation angle readings can beobtained toanaccuracy of+0.3° out to about 55miles range. The horizontal antenna pattern ofboth sets isafixed widt beam covering approximately 60° oneither side ofapredetermined ‘‘!inc of shoot ‘‘ The indicator isanE-scope inwhich ahorizontal intensity-modl~i~ te(i range s~veep moves vertically upthetube insynchronism with tlw~n~nw- FIG.622,-British A.Y1.E.S.Type 13height findeI ment ofthe radar beam. 
 147, pt. F, no. 4, pp. 
 FREQUENCY  RADAR IS SOMEWHAT LESS VULNERABLE TO AN !2- ATTACK OWING TO THE DIFFICULTY OF IMPLE 
 TION ITSELF IS TO BE FULLY CHARACTERIZED  TWO ORTHOGONAL POLARIZATIONS MUST BE TRANSMIT 
 PATTERN NULL IN A PHASED ARRAY SYSTEM GIVES GOOD BEAM 
 EFFECTS CHART &IGURE   SHOWS THAT THERE ARE CERTAIN CHOICES OF FREQUENCY RATIO THAT PROVIDE SPURIOUS 
 67. Lorra/Tramar Design—Feasibility Study, Malibu Res. and TRW, MRA p. 
 11.3), except that the flange isslightly beveled soastoallow f9°relative motion. This “wobble joint” isenclosed inaflexible airtight tube. The AN/APS-6.—The AN/APS-6 system imposes unusual require- ments onthescanner (Fig. 
 Pottier, “A review of target decomposition theorems in radar polarimetry,”  IEEE Trans. Geoscience and Remote Sensing , vol. 34, pp. 
 R., C. A. Fowler, and H. 
 In the indirect method, presynchronized stable clocks are  used by the receiver and a dedicated transmitter. The receiver measures the time inter - val ∆Ttt between the transmission of a signal and reception of the target echo. It then  calculates the range sum as ( RT + RR) = c∆Ttt. 
 CHAPTER 3 RECEIVERS John W. Taylor, Jr. Westinghouse Electric Corporation 3.1 THE CONHGURA TION OF A RADAR RECEIVER The function of a radar receiver is to amplify the echoes of the radar transmission and to filter them in a manner that will provide the maximum discrimination be- tween desired echoes and undesired interference. 
 17. Cumming, I.G.; Wong, F.H. Digital Signal Processing of Synthetic Aperture Radar Data ; Artech House, Inc.: Norwood, UK, 2005. 
 J. Willis, Bistatic Radar,  2nd Ed., Silver Spring, MD: Technology Service Corp., 1995.  Corrected and republished by Raleigh, NC: SciTech Publishing, Inc., 2005. 
   (& /6%2 
 Ward, “Space time adaptive processing for airborne radar,” MIT Lincoln Laboratory  Technical Report #1015, December. 13, 1994. 22. 
 The effect of noise is shown by the dashed curve. Noise  displaces the zero crossing by an amount L\t.  Using the calculus of variations, Mallinckrodt and Sollenberger3 show that the Fourier  transform Sg(/) of the optimum gating function which minimizes the time-delay error  [Eq. 
  
 11.8 Measured RCS pattern of a 39-wavelength 15° half-angle metal ogive. (Copy- right 1958, IEEE.7)MEASURED POINTS CALCULATED BY OPTICSCALCULATED CURVE DUE TO TRAVELINGWAVES CALCULATED MAXIMA DUE TO TRAVELINGWAVESECHOAREAIn (dB) ABOVEA SQUARE WAVELENGTH . The dominant scattering mechanisms for the right circular conducting cone are the tip and the base. 
  
 from pattern measurements or theory are directive gains. If the antenna gain fig- ures supplied for use in the range equations of this chapter are of the latter type, they must be converted to power gains by dividing them by the appropriate loss factor. For many simple antennas the ohmic losses are negligible, and in those cases the power gain and the directive gain are virtually equal. 
 FIG. 16.25 Block diagram of an adaptive processing module. The weights Wn and W12 are determined by the Howells-Applebaum algorithm.17 The correlation between the input signal V1-(O and the output signal V0(t) is determined by multiplying V0(t) by the complex conjugate of the input signal V*f (t) and averaging the resultant by passing it through a low-pass digital filter. 
 19.4). Since amplitude-modulation (AM) noise in sources is generally well below frequency-modulation (FM) noise (20 dB is typical), the noise reduction techniques concentrate on FM noise. Guidance Fundamentals.7 12 A detailed discussion of guidance is beyond the scope of this chapter. 
  AND !LMAZ 4HE FIRST EXCEPTION TO THIS RULE WAS 2!$!23!4 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars.  SPACE-BASED REMOTE SENSING RADARS  18.636x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 CloudSat.  Launched in April 2006, CloudSat includes as its primary payload  the Cloud Profiling Radar153 (CPR). 
 "EAM )NTERFERENCES    0HASED 
 Potenza, “Inverse SAR and its application to aircraft classifica - tion,” in IEEE Int. Radar Conf. Rec ., pp. 
 DOCUMENTED   SPLITTING AND COMBINING TECHNIQUES &IGURE   4HESE TECHNIQUES ALSO ADDRESS    ISOLATION BETWEEN PARALLELED AMPLIFIERS (AVING ISOLATION BETWEEN ADJACENT PORTS MEANS THAT IF ONE DEVICE FAILS  THE POWER COMBINER PROVIDES A FIXED LOAD IMPEDANCE TO THE REMAINING DEVICE HOWEVER  HALF THE POWER OF THE REMAINING ACTIVE DEVICE WILL BE DISSIPATED IN THE ISOLATION RESISTOR OF THE COMBINER )N ORDER TO ACHIEVE THE MOST EFFICIENT COMBINING OF PARALLEL AMPLIFIER STAGES  THE PHASE AND AMPLITUDE BALANCE OF INDIVIDUAL STAGES SHOULD BE AS SIMILAR AS POSSIBLE !NY DEVIATIONS FROM IDENTICAL PHASE AND AMPLITUDE BALANCE RESULT IN POWER OUTPUT LOST TO THE RESISTIVE TERMINATING PORT OF THE COMBINER 4HE POWER LOST TO SIMILARITY DIFFERENCES  FROM EITHER PHASE OR AMPLITUDE  IS DICTATED BY VECTOR ADDITION AND IS GIVEN BY  0 ,/34    LOG 31240   0    0 0 #/3P   0   0       WHERE P  IS THE PHASE DIFFERENCE IN DEGREES BETWEEN TWO AMPLIFIERS THAT ARE SUMMED  TOGETHER  3124 INDICATES THE hSQUARE ROOT OF v  AND  0 AND 0 ARE THE POWER LEVELS OF  EACH AMPLIFIER IN WATTS &IGURE   QUANTIFIES THE IMPACT OF LOST PERFORMANCE DUE TO  PHASE OR AMPLITUDE IMBALANCE. 
 20.6, so the  resulting σ0 is roughly independent of frequency over the range of frequencies for  which the power law behavior is observed. An important consequence is that with such  a reference, propagation path losses may be estimated. To test this idea, the magnitude and variability of svv° was examined with the San  Clemente Island HF surface wave radar.78 This radar facility had several valuable and  unique features: a transmission path out over the open sea, multiple-frequency operation  within a repetition period, calibrated antennas, known transmitter power, and ground  truth in the form of ocean waveheight recordings. 
 171–172. 14. G. 
 H.: Modified Magic Tee Phase Shifter, IRE Trans., no. PGAP-1, pp. 126-134, February,  1952. 
 RADAR SYSTEMS   (Digital Notes)     By  Dr. C. Ravi Shankar Reddy   Mrs.S. 
 Ê /Ê* 
 However, the above ArcSAR imaging algorithms perform the imaging on the reference plane. The imaging accuracy of the ArcSAR system is a ﬀected by the terrain ﬂuctuation. For rotating scanning ArcSAR system, even if the targets in the scenes have the same range and Doppler with the antenna, the targets with di ﬀerent height have di ﬀerent range migration. 
 POLARIZATION RADAR CAN MEASURE ONLY A SINGLE  PARAMETER  : AND MUST ASSUME 2AYLEIGH SCATTERING 3INCE THE RAINFALL RATE DEPENDS UPON  TWO PARAMETERS   . AND ,  IT IS NOT SURPRISING THAT %Q  IS NOT UNIVERSAL $ESPITE  THIS FACT  "ATTAN LISTS FOUR EXPRESSIONS AS BEING hFAIRLY TYPICALv FOR THE FOLLOWING FOUR  TYPES OF RAIN     3TRATIFORM RAIN :    2      /ROGRAPHIC RAIN :    2                 4HUNDERSTORM RAIN :    2                 3NOW :    2   3TRATIFORM REFERS TO WIDESPREAD  RELATIVELY UNIFORM RAIN AND USES THE WELL 
 The loaded Qof thecavity ismade very low (approxi- mately 5)byalarge windowin theend. The cavity isplaced inseries with theFIG.11.lS.—1B35 broadband ATR tube and mount; 3-cm band. magnetron line bysimply substituting theface ofthetube containing the window foraportion ofthebroad side ofthewaveguide. 
 The power output level from a particular device is a function of the exact operating frequency and the operating conditions, namely, the pulse width and duty cycle, and within normal operating constraints bipolar transistors can provide power outputs in the 50-W through 500-W range. These devices have been used for successful designs in the UHF through L-band fre- quency ranges, as noted in Table 5.1. Bipolar devices satisfy system require- ments of reliability, electrical performance, packaging, cooling, availability, and maintainability. 
 The increased use of pulse doppler  filter banks in modern radar has, however, led to a use of the IEEE definition where  the averaging of the signal-to-clutter ratio improvement is performed only across a  narrow region around the peak of the doppler filter response. In this case, the coherent  integration gain of the doppler filter is automatically added to the conventional MTI  improvement factor value and much better radar performance is indicated. Since a definition of clutter suppression is often needed, which quantifies the inher - ent radar stability limitations, apart from any additional coherent gain, it is sometimes  preferable to use the IEEE definition of clutter attenuation. 
 TIONS !S MENTIONED EARLIER  HARD 8 
 FIGURE  2.47 Elliptic filter CW response and response to weather with s  = 1 and 4 m/s rms  spectral spreadWx1 m/sspectral spread Wx4 m/sspectral spread CW Response −70−60−50−40−30−20−10010 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Relativ e Doppler - σfTRelative Response - dBWx 1 m/s spectral spread Wx 4 m/s spectral spread CW Response ch02.indd   48 12/20/07   1:44:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 Turn up the gain to the required level (max. for long-range use). d. 
  
 thebeammightnotbeasnarrowonthehorizon asmightbe obtained withaconventional antenna configuration ofequivalent aperture. Aswithanyarray Variable phosecanlrolsFigure8.32Domeantenna forachieving hemispherical coverage. (Courtesy IEEE.). 
 ATES THAT POWER UNIFORMLY IN ALL DIRECTIONS !LTHOUGH THE VAST MAJORITY OF TARGETS DO NOT SCATTER ENERGY UNIFORMLY IN ALL DIRECTIONS  THE DEFINITION ASSUMES THAT THEY DO 4HIS PERMITS ONE TO CALCULATE THE SCATTERED POWER DENSITY ON THE SURFACE OF A LARGE SPHERE OF RADIUS  2 CENTERED ON THE SCATTERING OBJECT  2 IS TYPICALLY TAKEN TO BE THE RANGE FROM  THE RADAR TO THE TARGET 4HE SYMBOL  R  HAS BEEN WIDELY ACCEPTED AS THE DESIGNATION FOR THE 2#3 OF AN OBJECT   ALTHOUGH THIS WAS NOT SO AT FIRST   4HE 2#3 IS THE PROJECTED AREA OF A METAL SPHERE THAT  IS LARGE COMPARED WITH THE WAVELENGTH AND THAT  IF SUBSTITUTED FOR THE OBJECT  WOULD SCATTER IDENTICALLY THE SAME POWER BACK TO THE RADAR (OWEVER  THE 2#3 OF ALL BUT THE SIMPLEST SCATTERERS FLUCTUATES GREATLY WITH THE ORIENTATION OF THE OBJECT  SO THE NOTION OF AN EQUIVALENT SPHERE IS NOT VERY USEFUL 4HE LIMITING PROCESS IN %Q  IS NOT ALWAYS AN ABSOLUTE REQUIREMENT )N BOTH MEA 
 FIG. 7.6 Array factor with N = 10 elements. where the effective aperture is a = Ns, which extends by s/2 beyond the centers of the end elements. 
 4, p. 177, August 1999. 117. 
 IES WELL INTO THE OPTICS REGION IF  ONE USES ARITHMETIC OF SUFFICIENT PRECISION  AND MANY  OPTICS APPROXIMATIONS CAN BE EXTENDED TO BODIES OF MODEST ELECTRICAL SIZE INTO THE RESONANCE REGION ,OW 
     . 
 POLARIZATION TO FULL 
 However,  at typical weather radar wavelengths longer than 3 cm, the attenuation is less than a  few hundredths dB/km and is usually ignored. Gaseous oxygen contributes only a  minor absorption effect at these centimeter wavelengths and is also usually ignored. Attenuation in Clouds. 
 Most media are reciprocal. Exceptions are gyrotropic media, such as ferrite materials and the ionosphere.103 Whenever the equivalence theorem is valid, KeIl41 provides a simple method for deriving bistatic RCS data from monostatic RCS data when plotted as a func- tion of target aspect angle. Bistatic RCS data for the same polarization is ob- tained by translating along the target aspect angle axis by one-half of the desired bistatic angle. 
 f. Kretschmer, Jr.: Design of a Staggered-prf Moving Target Indication Filter,  Tire Radio and Electro11ic Engi11eer, vol. 43, pp. 
 18.18 would provide a relatively good difference-channel taper, having smoothly tapered E fields on each antenna. However, a sum-signal excitation with the two antennas provides a two-hump in-phase E-field distribution which causes high sidelobes since it looks like a two-element array. This problem may be reduced by allowing someTARGET ANTENNA 2 ANTENNA 1 (a) RADIATION PATTERNS MIXERIFAMPLIFIER DUPLEXER TRANSMITTERLOCALOSCILLATORPHASEDETECTORANGLE-ERROR INFORMATION MIXERIFAMPLIFIERENVELOPE DETECTORRANGEINFORMATION . 
 (Additional delay cancelers perfectly cancel additional waveform derivatives; e.g., a  three-delay canceler will perfectly cancel V(t) = c + at + bt2.) A stagger system with  two pulse intervals samples the linear waveform at unequal intervals, and therefore  FIGURE 2.43  Effect of feedback on the velocity response curve: dual canceler, 6:7:8 pulse- interval ratio ch02.indd   43 12/20/07   1:44:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 Geophys. Res ., vol. 108, no. 
 MTI RADAR  2.396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 In theory, it is possible to synthesize almost any velocity response curve with digi - tal filters.26 As mentioned earlier, for each pair of poles and pair of zeros on the Z  plane, two delay sections are required. The zeros are controlled by the feedforward  paths and the poles by the feedback paths. Velocity response shaping can be accomplished by the use of feedforward only  without the use of feedback. 
 no. 105, pp. 178-183. 
 36. Boyd. C. 
 After the comb stage, the signal is decimated by a factor R (denoted  by the ↓R block) by only passing every Rth sample. In most applications, the number  of stages in the shift register, D, is equal to the rate change factor, R. Figure 25.36 b  depicts a CIC interpolator, where upsampling by a factor of R (denoted by the ↑R block)  is followed by a comb section and an integrator. 
 “Transfer standards for digital hydrographic data,” Publication S-57, International Hydrographic  Organization, Monaco. 25. H. 
 RESOLUTION  TECHNIQUES ,ONG TIME AVERAGES OF THE DATA DO NOT  IN PRACTICE  GIVE TARGET ELEVATION THUS  THE MULTIPATH ANGLE ERROR HAS NO SIMPLE SOLUTION AND IS GENERALLY MINIMIZED BY USING NARROW 
 L.: Predictions of Backscatter Clutter Power in the Radar C Computer Pro- gram, final report on NRL Contract N0014-84-C-2451; CU5-36903, University of Colorado, Boulder, June 9, 1986. 41. Davies, K.: "Ionospheric Radio Propagation," Nat. 
 13.5) that oftell cxliibit non-Rayleigli characteristics. especially with high-resolution  ritditr . '1'11~ log-F-I.(' II;IS soli~ctiriics I1cc1i cnllctl tr~c~crtlic~r ,fi.u. 
 Inthe i-famplifier astrong component is found due tothe beat between leakage from the transmitter and power from the local oscillator, and amuch weaker component, due tothe target, displaced bythedoppler frequency. After suitable amplification these two frequencies are passed into asecond detector whose output signal consists ofad-c component associated with leakage from the 1Itisnotdifficult tomake systems that determine onwhich sideofthecarrier the sideband lies, andarethus able todiscriminate between approaching andreceding targets.. 134 C-W RADAR SYSTEMS [SEC. 
 The effect ofscan speed onthreshold-signal level isoften called “scanning loss,” the condition ofscan-speed zero being implied asthe standard ofreference. This condition merits nomore than any other the distinction ofbeing astandard. On the contrary, the factors determining Stim areinthis case especially elusive, ifone wants totake them allinto account. 
 (Aradarwhichemploys multiple pulse repetition frequencies toavoidblindspeedsisusuallyclassedasanMTIifitsaverage prf wouldcauseblindspeeds.Thejustification forthisdefinition isthatthetechnology anddesign philosophy ofamultiple prfradararemorelikethatofanMTIthanapulsedoppler.) Thepulsedoppler radarismorelikelytouserange-gated doppler filter-banks than delay-line cancelers. Also,apoweramplifier suchasaklystron ismorelikelytobeusedthana poweroscillator likethemagnetron. Apulsedoppler radaroperates atahigherdutycycle thandoesanMTI.Although itisdifficulttogeneralize, theMTIradarseemstobethemore widelyusedofthetwo,butpulsedoppler isusuallymorecapableofreducing clutter. 
 21–28,  November 2007. 36. L. 
 REPEAT ORBITS  TO  DAYS   AND AS A CONSEQUENCE  HAVE WIDELY SPACED  KM TO  KM  GROUND TRACKS 3UCH ORBITS  CANNOT RESOLVE THE SHORT 
 END HARDWARE  WIDE DYNAMIC RANGE !$S  CLUTTER REJECTION FILTERING INCLUDING 34!0   PULSE COMPRESSION SIDELOBE SUPPRESSION  DOPPLER FILTER SIDELOBE CONTROL  GUARD CHANNEL PROCESSING  RADOME REFLEC 
 MATELY PROPORTIONAL TO WAVELENGTH 4HE RADARS WAVEFORM WAS CON STRAINED SO THAT ALL  SIDELOBES WERE AT LEAST  D" BELOW THE MAIN 
 NOISE RATIO ALLOWED THE RADAR RANGE EQUATION TO DEVELOP SUFFICIENTLY TO BE USEFUL IN RADAR PERFORMANCE ANALYSIS  DEVELOPING COMPUTER TECHNOLOGIES ALLOWED FOR MORE SOPHISTICATED RADAR RANGE EQUATION SOLUTION TECHNIQUES 4HUS  SOLUTION TECHNIQUES TO THE RADAR RANGE EQUATION MIGRATED FROM PENCIL AND PAPER hWORKSHEETSv TO SIMPLE COMPUTER PROGRAMS AUTOMATING T HE hWORKSHEETv TO  HIGHLY SOPHISTICATED COMPUTER PROGRAMS ACCOUNTING FOR TECHNOLOGY ADVANCES IN SIGNAL PROCESSING AND ENVIRONMENTAL MODELING 4HE INTENT OF THIS CHAPTER IS TWOFOLD 4HE FIRST IS TO FOCUS ON ONE PARTICULAR TERM  OF THE RADAR RANGE EQUATION  THE PROPAGATION FACTOR  & 0 DEFINED IN 3ECTION    %NCOMPASSED WITHIN THE PROPAGATION FACTOR ARE ALL THE EFFECTS UPON PROPAGATION ATTRIB 
 12.5a). Another effect is the introduction of errors in the measurement  of elevation angle (Fig. 12.5h) .. 
 500–505. 78. A. 
 Since,  in principle, two independent looks can measure only two components of vector air  motion, the assumption of atmospheric mass continuity is invoked. This equation of  mass continuity53( )∇ ⋅ =V0is used to obtain the third-dimensional component, where  V is the vector air motion and is constrained to be zero at the surface. The vertical air  motion is calculated from vertical integration of the mass continuity equation. 
 9-15. Janu-  ary. 1970. 
 IZATIONS SO THAT DATA COULD BE COLLECTED FOR CROSS 
 If clutter  were not present, tlie desired targets would not be detected. It is possible, however, to provide  a switch to disconnect the noncoherent MTI operation and revert to normal radar whenever  sufficient clutter echoes are not present. If the radar is stationary, a map of the clutter might be  stored in a digital memory and used to determine when to switch in or out the noncoherent  hlT1. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar.  METEOROLOGICAL RADAR  19.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 Meischner’s Weather Radar29 provide an evolving perspective on many aspects of meteo - rological radars by technological and scientific leaders. 
 The  statistical description of the antenna properties cannot be applied to any particular antenna,  but applies to the collection of similar antennas whose errors are specified by the same  statistical parameters.  The ensemble average power pattern' of a uniform array of M by N isotropic elements  arranged on a rectangular grid with equal spacing between elements can be expressed as 109  M N  IJ(B, </>)12 = P;e-,plfo(B, </>)12 + [(1 + !l2)Pe -P;e-62J L Li;," (8.24)  m=I n=I  where Pe= probability of an element being operative (or the fraction of the elements that  remain working)  f> = phase error (described by a gaussian probability density function)  I .to( o, <t>) 12 = no-error power pattern  !l = amplitude error ·  imn = no-error current at the mnth element  Thus the effect of random errors is to produce an average power pattern that is the superposi­ tion of two terms, similar to Eq. (7.31) for the continuous aperture. 
 W. K. Saunders, “CW and FW radar”; F. 
 Ifthe system isscanned, thebeam will beonthetarget foronly afinite time, with theresult that even asingle-frequency doppler signal will bespread over aband whose extent will beroughly the reciprocal ofthe time during which the beam isonthe target. This isobvious enough, and would not beworth further discussion, were itnot forthe fact that the same consideration arises inconnection with the system’s ability to reject clutter. The presence ofscattering objects onthe ground gives rise, aswehave seen, toad-c component inthe output signal ofthe second detector. 
 LEVEL $"& HAS FAR FEWER DEGREES OF FREE 
 two separate antennas with the distance between them equal to TPv, = Tpu sin 0,, where  0, = angle between velocity vector of the vehicle and the antenna beam-pointing direction,  and Tp = pulse repetition period. One pulse is transmitted on the forward antenna, and tllc  other pulse is transmitted on the rear antenna so that the two pulses from the two different  antennas are transmitted and received at the same point in space. The result is as if the  radar antenna were stationary. 
 PULSE PHASE COHERENCY &OR THIS EXAMPLE  WITH AN )& CENTER FREQUENCY OF  -(Z AND A COMPLEX SAMPLE RATE OF  -(Z  ALLOWABLE 02) CLOCK FREQUENCIES WOULD INCLUDE  -(Z AND  -(Z (ARDWARE  )MPLEMENTATION  4ECHNOLOGY  )N THE PAST  IMPLEMENTING A REAL 
 Antenna rotation for the system  is at 5, 6 or 10, 12 revolutions per minute (rpm), providing 360 ° azimuth coverage  while electronically step-scanning in elevation. It provides full performance over  a nominal 20 ° in the elevation plane to an altitude of 100,000 feet and up to 60 °  in elevation during TBM tracking. The antenna/array incorporates monopulse radar  techniques. 
 (The only available means for locating aircraft pr'ior to World War Il were sound locators  whose maximum detection range under favorable conditions was about 20 miles.) Watson- ._,, Watt was allowed to explore the possibilities of radio detection, and in February, 1935, he  issued two memoranda outlining the conditions necessary for an effective radar system. In that  same month the detection of an aircraft was carried out, using 6-MHz communication equip­ ment, by observing the beats between the echo signal and the directly received signal (wave  interference). The technique was similar to the first United States radar-detection experiments. 
 c, = In (N,/N = a constant which depends upon value of N, and N the latter being refrac-  tively at altitude of 1 km  It is found that the exponential model gives a more accurate determination of the effects of  atmospheric refraction than does a linear model.  The use of the correct atmospheric model is quite important in a height-finder radar;  especially for targets at long range~.l~*"*'~ Refraction causes the radar rays to bend, resulting  in an apparent elevation angle different from the true one. In certain radar applications,  corrections must be made to the radar data to obtain a better estimate of elevation angle,  range, or height.lg Surface observations of refractivity often suffice for ascertaining the  effects of refra~tion.~~~~  Refraction is troublesome primarily at low angles of elevation, especially at or near the  horizon. 
 57.-Transmitter-receiver chassis of10-cm doppler system. (Courtes~ of,spewV Gyroscope Company, Inc.) thearrival ofthe reflected pulse. This modulation gives rise toalarge number ofsidebands, and the distance ofthe target may beregarded asdetermining therelative phase shifts ofthevarious sidebands ontheir return path. 
 A“beforeandafter” picture isshown inFigure 13.55. Many variations ofthis technique are possible. One, \vhich has been applied toexisting sets inwhich anadditional channel isdifficult toinstall, consists ofswitching the gain upand the limit level down on alternate pulse cycles bymeans ofascale-of-two multivibrator, the results being added onthe cathode-ray-tube screen. 
 M. Thiebaud: A Scan Converter Radar Display System, Naval Research  Laboratory Memorandum Report 2979, Washington, D.C., January, 1975.  34. 
 When the two  signals slip in phase by 1 cycle, the measurement of phase, and hence range, becomes  ambiguous.  The two-frequency CW radar is essentially a single-target radar since only one phase  difference can be measured at a time. If more than one target is present, the echo signal  becomes complicated and the meaning of the phase measurement is doubtful. 
 140- 146, April 1972. (Reprinted in ref. 18.)  29. 
 Frequent indications that the antenna system is functioning or is capable of func- tioning should be available. In one possible method the phase shifters are pro- grammed to focus on a nearby monitor probe and scan past it.21 This will yield a close approximation of the complete radiation pattern, where gain and sidelobes can be measured and compared with previous results. The contribution of indi- . 
 Remote Sens. 2002 ,40, 2375–2383. [CrossRef ] 7. 
 LOG BEAMFORMING ARRAY 3INCE $"& CAN PRODUCE MULTIPLE SIMULTANEOUS BEAMS  ENERGY CAN BE TRADED OFF FOR IMPROVED SEARCH FRAME TIMES AS WAS DISCUSSED IN 3ECTION  £Î°£ÎÊ , /" Ê*// 
 FREE WHERE  . IS THE  NUMBER OF &- SLOPES (OWEVER  THIS  PROBLEM IS NOT SEVERE IN PRA CTICE  SINCE MULTIPLE  TARGETS IN A SINGLE BEAMWIDTH ARE USUALLY A TRANSIENT PHENOMENON 4HE ACCURACY OF THE RANGE MEASUREMENT IMPROVES AS THE &- SLOPE INCREASES SINCE  THE OBSERVED FREQUENCY DIFFERENCES CAN BE MORE ACCURATELY MEASURED 4HE &- SLOPE IS   HOWEVER  LIMITED BY CLUTTER 
 STATE TRANSMITTER CONFIGURATIONS MAY COMBINE MANY AMPLIFIERS IN PARALLEL  TO A SINGLE ANTENNA PORT  A   OR MAY USE PHASE 
 1958.  24. Crane. 
 17 1, 13;1ugli. R. A.: "('o~iiputer Control of Modern Radars," Privately published by RCA Inc., 1973. 
 BACKED CONES  DOUBLE ROUNDED CONES  AND  CONE SPHERES v )%%% 4RANS  VOL !0 
 it can contribute significant attenuation. Since the same transmis­ sion line is generally used for both receiving and transmission, the loss to be inserted in the  radar equation is twice the one-way loss.  The signal suffers attenuation as it passes through the duplexer. 
 POLARIZATION  CLUTTER MODEL FOR SNOW  A  DAY AND  B  NIGHT .OTE THE  LARGE DIFFERENCES (ORIZONTAL POLARIZATION IS SIMILAR  AFTER 2 + -OORE  + ! 3OOFI  AND 3 - 0URDUSKI  Ú )%%%  . £È°Î{  2!$!2 (!.$"//+  &)'52%      RANGE OF PIXEL AMPLITUDE VERSUS RESOLUTION &)'52%     !NGULAR PATTERNS OF THE MEAN  UPPER DECILE  AND LOWER DECILE OF 3KYLAB  SCATTEROMETER OBSERVATIONS OVER .ORTH !MERICA DURING THE SUMMER SEASON  FROM -OORE ET AL   5NIVERSITY OF +ANSAS 2EMOTE 3ENSING ,ABORATORY 4ECHNICAL 2EPORT  
 107–124,  January 1987. 101. R. 
 In the above, a rapid antenna-rotation rate takes advantage of the fact that  the clutter echo changes with time, but the target echo does not. With a high-resolution radar  (nanoseconds pulse width) the individual sea-clutter spikes, as mentioned in Sec. 13.3, can  persist for several seconds, which is much greater than the to ms decorrelation time quoted for  X-band sea clutter. 
 DRIVEN AIR CURRENTS EVENLY DISTRIBUTES THE COMPONENTS OF THE ATMOSPHERE !T ABOUT  KILOMETERS  THE MIXING DECREASES TO THE POINT WHERE THE GASES TEND TO STRATIFY IN ACCORDANCE WITH THEIR WEIGHTS 4HE LOWER  WELL 
 The result is that 2 W of power may be han- dled in the manually tuned version, and up to 1000 W in the servo-tuned equip- ment. The balance of the circuitry is shown in Fig. 14.5. 
 References 1. Martorella, M.; Pastina, D.; Berizzi, F.; Lombardo, P . Spaceborne radar imaging of maritime moving targets with the Cosmo-Skymed SAR system. 
 The radar systems designer mirst  prevent this by forcing the jammer to spread its power over a mi~cli wider band. This can be  accomplished by changing the radar frequency from pulse to pi~lse in an unpredictable fasliion  over tlie entire tuning band available to tlie radar. A radar capable of changing its frequency  from pulse to pulse is said to possess ji-eq~rency crgility. 
 Theprobability-density functionp(x)isthendefinedas ()1.(number ofvaluesinrange ~xatx)1~xpx=1m (2.8) &X-'O totalnumber ofvalues=NN-.oo Theprobability thataparticular measured valuelieswithintheinfinitesimal widthdx centered atxissimplyp(x)dx.Theprobability thatthevalueofxlieswithinthefiniterange fromx1toX2isfoundbyintegrating p(x)overtherangeofinterest, or Probability (Xl<X<X2)=f2p(x)dx XI Bydefinition, theprobability-density function ispositive. Sinceeverymeasurement mustyield somevalue,theintegraloftheprobability densityoverallvaluesofxmustbeequaltounity; thatis, fOOp(x)dx=1 -00(2.10) Theaverage valueofavariable function, q,(x),thatisdescribed bytheprobability-density function,p(x),is (q,(x).v=fooq,(x)p(x) dx -00(2.1l) Thisfollowsfromthedefinition ofanaveragevalueandtheprobability-density function. The mean,oraverage, valueofxis (x).v=ml=f00xp(x)dx -00 tProbabilities aresometimes expressed inpercent(0to1(0)ratherthan0to1.(2.12). 
 The impact of antenna array elec - trical requirements on the packaging of MMIC components into a T/R module is fun - damental. The periodic nature of digital phase shifting at each radiating element can  create multiple distinct locations in space where parasitic beams (grating lobes) can  occur. In array design, this is avoided if the radiating element spacing ( d) is less than  that described by  d < (l*(1 + sin(q))−1  (11.5) Where d is the spacing between adjacent radiating elements, l is the wavelength of  the highest operating frequency, and q  is the maximum scan angle of the array. 
 Aone-me~ahertz-bandwidth signal,forexample. iscapableof conveying information atarateoftwomegabits/s, butanoperator canacceptaninformation rateofonly10to20bits/soThusthereisatremendous mismatch between theinformation contentofaradarandtheinformation-handling capability ofanoperator. Thefunction ofthe radardisplayistoaidtheoperator toextractinanefficientmannertheinformation contained intheradarsignalthatisimportant tothetask.Theusualtypeofradardisplayisacathode­ raytubeoritsequivalent. 
 Telemetry Council, 1987. 18. R. 
 BASED STATION  IN A DOWN 
 TRIGGER PULSES 4RACKING BANDWIDTH IS USU 
 TO 
 W. H. Stiles and F. 
 orreflectivity, isdefined as (Je 'T=I' ( where (Jeinthiscaseistheradarcrosssectionrromthevolumev,.. 13.2SURFACE-CLUTI'ER RADAR EQUATIONS(tJ,2) Consider thegeometry orFig.13.1whichdepictsaradarilluminating thesurraceatagrazing angle<p.Itisassumcd thatthewidthoftheareaI1cisdetermined bytheazimuth beamwidth On,butthatthedimension intherangcdimension isdetermined bytheradarpulsewidthr ratherthantheelcvation beamwidth. Usingthesimpleradarequation ofSec.1.2,thepower Creccivcd fromthccluttcris (13.3) Radarr; (al Clutter 00 Radar 00 ~88000 00o00o00 (blR8e Figurel3.1Geometry ofradarclutter.(a)Elevation viewshowing theextentofthesurfaceintercepted by theradarpulse,(b)planviewshowing clutterpatchconsisting ofindividual. 
 Although disappointing, these trials indicated areas where improvements should be made. It was decided to install ASV in Hudson, Sunderland, Botha and Beaufort aircraft. By the middle of January 1940, 32 MU had installed ASV Mk. 
 BASED INSTRUMENTATION RADARS  WHERE IT IS LESS EXPENSIVE TO IMPLEMENT AND MORE TIME IS AVAILABLE FOR DATA COLLECTION +NOTT ET AL    PP     .EVERTHELESS  FOR THE MOMENT  WE ASSUME THE STEP 
 The receiver WN now continue tofunction inthepresence ofa c-w simal until the i-famplifier isoverloaded. The i-foverload limit can beincreased byopera~ing the last stage ortwo with higher plate- supply voltage. Frequently apower tube, such asthe 6AG7, isused in the last stage toincrease the output capabilities ofthe i-famplifier, although the6AK5 has proven fairly satisfactory inthis application. 
 245-248, IEEE Pub. no. 76 CH 1151-0ED. 
 When the echo from the sea can be modeled as that from a number of independent, random  scatterers, with no one individual scatterer producing an echo of magnitude conlmensurate  with the resultant echo from all scatterers, then the amplitude fluctuations of the sea echo is  described by the gaussian probability density function. [Eq. (2.15)). 
 39. A. Thomson, A GRAVES Sourcebook,  version of 2006-10-27, thomsona@flash.net. 
 The modes are: fine-resolution strip-map-1 (3-m resolu - tion, 30-km swath, dual-polarization); fine-resolution strip-map-2 (12 m at 30 km,  quadrature-polarization); medium resolution ScanSAR (25 m at 120 km, dual-polar - ization); coarse resolution ScanSAR (50 m at 240 km, dual-polarization); and high- resolution SpotSAR (better than 2 m, 10-km square image frame, dual-polarization).  The SpotSAR mode requires yaw/pitch steering of the spacecraft to ±13°. Coverage  to either side of the ground track requires a roll maneuver of the spacecraft to direct  the antenna pattern to the opposite side of nadir, an approach that is similar to that of  RADARSAT-2. 
 FIELD  CALIBRATION  &ACTORY CALIBRATION IS ONLY PERFORMED ONCE  USUALLY AT THE ANTENNA TEST  RANGE OF THE PHASED ARRAY MANUFACTURER )N 
 Holland, M. G., and L. T. 
 The essential features of skywave propagation can be seen in Figure 20.1. The  ionosphere, being an ionized gas with free electrons, will reflect all radar signals when  the radar frequency is less than the plasma frequency  given by  f NP e ≅ ×−9 106  (20.1) FIGURE 20.1  Ray-tracing through a model ionosphere, showing the variation of the radar footprint  with carrier frequency. The contours map the plasma frequency or electron density. 
 LINE CURVES ARE LOWER BOUNDS DERIVED BY 3WERLING  AND  POINTS SHOWN ARE SIMULATION RESULTS AFTER 6 ' (ANSEN Ú )%%%   . Ç°n  2!$!2 (!.$"//+  WHEN  
  OR  
 When a limiter is used preceding the pulse-compression filter in conventional pulse-  cornpression radar for suppressing impulsive and other interference, the presence of multiple  targets can cause degraded performance. If the uncompressed pulse has an amplitude less than  the rrns noise level, there is little degradation. This situation will apply in many cases when the  pulse-compression ratio is large. 
 2 of" Microwave Scanning Antennas, Vol. III," R. C. 
 Painstaking design is necessary. The switches may be diodes  or circulators. Leakage past the switches may be reduced by adding another switch  in series in each line. 
 NIQUE IS THAT THE PROBABILITY DENSITY OF THE NOISE IS KNOWN EXCEPT FOR A FEW UNKNOWN PARAMETERS 4HE SURROUNDING REFERENCE CELLS ARE THEN USED TO ESTIMATE THE UNKNOWN PARAMETERS  AND A THRESHOLD BASED ON THE ESTIMATED PARAMETERS IS OBTAINED 4HE SIM 
 It is usually a suitable  substitute for the short-pulse waveform except when a long minimum range might be a problem  or when maximum immunity to repeater ECM is desired. Pulse compression radars, in addition  to overcoming the peak-power limitations, have an EMC (Electromagnetic Compatability)  advantage in that they can be made more tolerant to mutual interference. This is achieved by  allowing each pulse-compression radar that operates within a given band to have its own  characteristic modulation and its own particular matched filter. 
 However, for the scale size of HF-band wavelengths the sea is a surface that is only slightly rough, and the method of Rice16 can be used to explain reflection. Backscatter from the sea can be considered a resonant inter- action. The disorganized-looking ocean waves are thought as being the sum of an infinite number of Fourier surfaces, each being a sinusoidally corrugated sheet with a different wavenumber and direction.17 The principal backscatter for a grazing-incidence electromagnetic wave comes from that component sheet that has a wavelength equal to one-half of the radar wavelength and that is either di- rectly approaching the radar or receding from it.18'19 The surface scattering co- efficient, or RCS per unit surface area (a°), is much larger for vertical than for horizontal polarization. 
 CIVIL MARINE RADAR  22.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 and fall times are usually longer. The extra high voltages involved can lead to poor  reliability if the design does not adequately address the associated problems. Careful  physical layout is essential and consideration must be given to the effects of operating  in a potentially damp environment. 
  % 
 Born and E. Wolf, Principles of Optics , New York: Pergamon Press, Macmillan, 1959. 51. 
 The features of ship05 and ship06 are shown in Figure 19. The features of the proposed method result are the least yet.   (a) (b)  Figure 18. 
 SCANNING ANTENNAv P   5NFOCUSED 3!2  4HIS TYPE OF EARLY 3!2 IS DESCRIBED BY #UTRONA  AS FOLLOWS h4HE  COHERENT SIGNALS RECEIVED AT THE SYNTHETIC ARRAY POINTS ARE INTEGRATED  WITH NO ATTEMPT MADE TO SHIFT THE PHASES OF THE SIGNALS BEFORE INTEGRATION 4HIS LACK OF PHASE ADJUST 
 Study Area and Data Preparation 2.1. Study Area Wuhan city (29◦58/primeN–31◦22/primeN, 113◦41/primeE–115◦05/primeE) is located in the east of an alluvial plain called Jianghan Plain, see Figure 1. The Yangtze River, the world’s third longest river, ﬂows through the heart of the city. 
 The display-tube sweeps must betriggered bythe appearance ofthe power pulse because ofthegreat uncertainty infiring time. Ifjisthespeed of the disk inrpm, and nisthenumber ofpins, theresulting pulse rate is nf/60. For agiven power output, there isanoptimum spacing between ~otating and fixed pins, and aminimum permissible spacing between pins inthe rotating disk. 
 The ERS mission parameters are used in the simulation and reported in the Table 1. 93. Sensors 2019 ,19, 1649 T able 1. 
 Mar.. 1957.  10. 
 ....... 8  Height  ................................ ................................ 
 Such features are explained by changes in the spectral density of Bragg waves responsible for the backscattering of radar signals [ 28]. In addition, brightness variations along eddy spirals are periodic. A change from bright to dark can be deﬁned as one alternation cycle, and the alternation cycle is related to the scale of the spirals, i.e., the alternation cycle increases as the spirals become longer. 
 LATITUDE  IONOSPHERIC MODEL v * 'EOPHYS 2ES VOL   PP n    'LOBAL !SSIMILATION OF )ONOSPHERIC -EASUREMENTS  0ARK #ITY  5TAH    HTTPGAIMCASSUSU  EDU'!)-HTDOCSPRESENTHTM  'LOBAL !SSIMILATIVE )ONOSPHERIC -ODEL  *0,  HTTPIONOJPLNASAGOVGAIMINDEXHTML  * $ (UBA  ' *OYCE  AND * ! &EDDER  h3!-) 3AMI IS ANOTHER MODEL OF THE IONOSPHERE    ! NEW LOW 
 655 1612 The Noncoherent Method. 656 16.13 Beating Due toFinite Pulse Packet 657 COMPONENT DESIGN .........................658 16.14 The Transmitter and ItsModulator. 658 16.15 The Stable Local Oscillator. 
 119.Kdlmykov. A.I..andV. V.Pustovoytenko: OnPolarization Features ofRadioSignalsScallacd FromtheSeaSurfaceatSmallGrazing Angles.J.GeophJ's. 
 ERATELY BUILT THE " 
 Elevation-angle estima- tion may be accomplished in such a radar by an amplitude comparison technique, by which the amplitudes of the return at the target range in two or more adjacentANTENNA 1 ROTATING STRUCTURESLANTED COSECANT- SQUARED FAN BEAMVERTICAL COSECANT- SQUARED FAN BEAM (9) PHASE DETECTTARGET ECHO PHASE SHIFT = —^ sin 0A . simultaneous elevation receive beams are compared. The technique is thus a spe- cial case of the general technique of simultaneous lobing. 
 13.46 areeliminated, with the result that theindicator isconsiderably simplified and errors due to imperfections inthe amplifier response areavoided. These advantages areaccompanied bycertain restrictions which, will appear below. Inorder toreduce the effects ofdistributed capacity inthe synchro and the deflecting coils, and ofthe shunt capacity ofthe cables, low- inductance windings offew turns are used throughout. 
 N jammers can produce N2 -N ghost  targets when two radars attempt triangulation.  Locating the jammer might not be as important, however, as locating the attacking  missiles or aircraft screened by the jam mer, especially when the jamming aircraft is beyond the  range of (\cfcnsive weapons. A jammer that operates outside the range of norm~I defenses is  known as a sta11d-of/jammer. 
 The mean square value (nt,) of the current  wl~eri rrlllltiplied by tile resistaricet gives the mean power. The mean square value of voltage  times tlie conductance is also the mean power. The variarlce is defined as  The variance is tile meall square deviation of x about its mean and is sometimes called the  secorld ceiltral rnonrcllt. 
 givcs  For jarnr~iing which enters via the antenna sidelobes rather than via the main beam, the  riglit-hand side of the above surveillance radar equation would be multiplied by tlie ratio of  rnaxirnum aliterina gain to tlie gain of the sidelobe in the direction of the jammer.  Repeater jamming. A target under observation by a radar can generate false echoes by delay-  ing the received radar signals and rctransrnitting at a slightly later time. 
 SEC. 17.8]PULSE METHOD FORRELAYING SINEANDCOSINE 707 separate channel. There must now be developed ad-c voltage whose value isatevery instant proportional tothe delay ofthesine pulse with respect tothebasic pulse. 
 However, if a threshold crossing is observed  from any range cell, a second pulse or set of pulses is transmitted with higher energy, and with  a different threshold. A target is declared to be present only if threshold crossings are observed  from the same range cell on both transmissions. The second transmission might also be of  greater resolution as well as higher power. 
 pp. 1354-1355.  September. 
 Davis. P., and A. Colien: Rigid Radome Design Considerations, Electronics, vol. 
  D"  RELATIVE TO THE MAINLOBE PEAK 4HIS )1- IS TYPICALLY  REFERRED TO AS THE h 
 Inajamming environment, itcanlulltheradaroperator intoafalsesenseof security sincetheidealCFAR,bymaintaining theoutputnoiselevelconstant nomatll.~rwhat theleveloftheinputnoise,provides noindication thatjamming ispresent. Additional means mustbeincorporated intoaCFARtoprovide theoperator withwarning ofthepresence of...nOiseJammIng. Asensitive receiver withalownoisefiguremaybedesirable inmanycivilianapplications ofradar,butinmilitary applications itisnotalwaysanassetsinceitmakesthereceiver more vulnerable tojamming. 
 Anintensity modulated displaywithheight(altitude) astheverticalaxis andrangeasthehorizontal axis. Theabovedefinitions aretakenfromtheIEEEStandard Definitions,23 withsome modifications. ThetermsA-scope andA-display, B-scopeandB-display, etc.,areusedinter­ changeably. 
 or  ( 11.8)  where  The error is illustrated in Fig. l l.3. The receiver output characteristic with signal s0 only is  represented by the solid curve. 
 STATE RADARS NM  .AUTICAL MILE     METERS 3!24  3EARCH AND 2ESCUE 4RANSPONDER3/'  3PEED /VER 'ROUND3/4$-!  3ELF /RGANIZING 4IME $IVISION -ULTIPLE !CCESS347  3PEED 4HROUGH THE 7ATER4#0!  4IME TO #LOSEST 0OINT OF !PPROACH643  6ESSEL 4RAFFIC 3ERVICES54#  5NIVERSAL 4IME #OORDINATED62-  6ARIABLE 2ANGE -ARKER. ÓÓ°Î{  2!$!2 (!.$"//+     "7 
 If you shout in the  direction of a sound -reflecting object (like a  rocky canyon or cave), you will hear an echo.  If you know the speed of sound in air, you can  then estimate the distance and gen eral  direction of the object. The time required for  an echo to return can be roughly converted to  distance if the speed of sound is known. 
 The individual spectral lines are separated by a frequency equal to the PRF. These spectral lines fall at precisely the same frequencies as the blind speeds in Fig. 15.8. 
 Air Force Tac- tical Air Command System (TACS). The radar employs a multiple-horn feed il- luminating a reflector-type antenna rotating at 6 r/min to generate a stack of six receive beams in elevation. The original version of the radar utilized a linear- beam Twystron tube to generate approximately 4 MW of RF peak power in a 6.5-|jLS simple pulse. 
 Ttie line feed is more difficult to pressurize than a point feed. The antenrla  with a point-source feed requires a reflector surface with double curvature, as compared to the  single curvature of the cylindrical antenna, in order to obtain a shaped beam. The double  curvature reflector is designed to provide both the desired shaping of the beam in one plane  and focusing in transverse  plane^.'*^^-^^ The surface is formed by the envelope of a system of  paraboloids whose axes all lie in the plane of the shaped beam, but at varying angles of  inclination to each other and to a fixed line. 
 Tracking radars that are based on CW, pulse-doppler, or MTI principles  can also track the doppler frequency shirt generated by a moving target. This may be accom­ plished with a frequency discriminator and a tunable oscillator to maintain the received signal  in the center of a narrow-band filter. It is also possible to use a phase-lock loop, or phase­ sensitive discriminator whose output drives a voltage-controlled oscillator to hold its phase in  step with the input signal.2 Tracking the doppler frequency shift with the equivalent of a  narrow-band filter just wide enough to encompass the frequency spectrum of the received  signal allows an improvement in the signal-to-noise ratio as compared with wideband proces­ sing. 
 where tk and T,, are defined in Fig. 2.4. The average duration of a noise pulse is approximately  the reciprocal or the bandwidth B, which in the case of the envelope detector is BIF. 
 When operating at high altitude, aswas typical for H 2S when bombing, the error between slant range and ground range could be signi ﬁcant. The operator could set the aircraft height on the height tube, using a variable height marker to align with the displayed ground return at theshortest range. Then, when the range maker was set over a target of interest, the ground range could be read from a set of curves on the range drum [ 8]. 
 102 oscillation isatleast oneless than thenumber ofoscillators. Figure 10.S /outputboll FIG, 10,7,—View from cathode ofanode block opened outtoshow longitudinal dis- tribution ofmagnetic field.shows the distribution ofcharge and electric field for amagne- tron oscillating inthe r/2-mode. Acomparison ofthe electric fields with those ofthe r-mode shown inFigs. 
 F. C. MacDonald, “The correlation of radar sea clutter on vertical and horizontal polarization with  wave height and slope,” in IRE. 
 The second class is comprised of heterogeneous areas wherein speckle noise is to be reduced, while preserving texture. The third class is comprised of areas containing isolated point targets that ﬁltering should preserve. The Enhanced Frost ﬁlter output can be given as: ˆI(to)=⎧ ⎪⎨ ⎪⎩¯I, for Cl(to)<Cu, IK1exp[−K(Cl(to)−Cu)/(Cmax−Cl(to))|t|], for Cu≤Cl(to)≤Cmax, I for Cl(to)≥Cmax,(1) where to=( xo,yo)is the spatial coordinate, ¯Iis the mean intensity value inside the kernel, Kis the ﬁlter parameter, K1is a normalizing constant, and |t|is the absolute value of the pixel distance from the center of the kernel at to. 
 undertheactionofthecrossed electricand magnetic fields.formintorotating electron (space-charge) bunches, orspokes.Thesebunches driftalongtheslow-wave circuitinphasewiththeRFsignalandtransfer energytotheRF wavetoprovide amplification. Insteadofthecollector electrode foundintheklystron andthe T\VT.thespentelectrons terminate inthecrossed-field amplifier ontheslow-wave anode structl!reo TheCFt\.depicted inFig.6.12iscalledreelltrallt, inthattheelectrons thatarenot collected afterenergyisextracted attheoutputportarepermitted toreentertheRFinterac­ tionareaattheinput.Thisimproves theefficiency ofthetube.Thereentering electrons, however, mightcontain modulation whichwillbeamplified inthenextpassthrough thecircuit.To circumvent thisthetubeofFig.6.12hasadriftspacetodemodulate theelectron streamsoasto removethisRFfeedback. Somecrossed-field tubes,suchastheAml--Iitron andtheforward-wave magnetron, donothavethedriftspaceandemploy thefeedback provided bythereentering electrons.IfthedriftspaceinFig.6.12isreplaced byacollector electrode whichterminates the electron stream,theCFAiscalledl1ol1ree1ltrant. 
 2016 ,184, 276–287. [ CrossRef ] 32. Liu, L.; Yan, Q.; Sun, H. 
 RANGE PERFORMANCE IS REQUIRED  AGAIN INCREASING THE REQUIRED TRANSMIT 
 An  inertial navigation system estimates the position of the aircraft in a worldwide coordinate  space by integrating the outputs of the gyros and accelerometers, typically using Kalman  filtering techniques. Accumulated errors in such a system can be corrected by using GPS  updates as well as known reference points measured with the radar, or EO sensors. There may be dozens or hundreds of stored program devices distributed throughout  the avionics. 
 corresponding toplatespacings of0.557,1.and0.625..1.andtopower rellcctions atnormal incidence orIIand6.25percent, respectively (Ref.1,p.410). Evenwithanindexofrefraction inthevicinity of0.5to0.6,thethickness ofthemetal­ platelensbecomes largeunlessinconveniently longfocallengthsareused.Thethickness may hereduced byzoningjustaswithadielectric lens.Thebandwidth ofazonedmetal-plate lens islargerthanthatofanunlOned lens,butthestepsinthelenscontour scattertheincident energyinundesired directions, reducethegain,andincrease thesidelobe level.Anexample of anX-bandmetal-plate zonedlensisshowninFig.7.20. Another classofmetal-plate lellsistheconstrained lens,orpath-length lens,inwhichthe raysareguidedorconstrained bythemctalplates.IntheH-plane metal-plate constrained ICllS.theelectric fieldisperpendicular totheplates(Hfieldparallel); thusthevelocity ofthe wavewhichpropagates through theplatesisrelatively unaffected provided theplatespacing is Figure7.20X-handmetal-plate zonedJens.. 
 Ifwedenote the total stored energy byW,and the energy dissipated during one r-fcycle byW,Qisgiven by 27rwQ=_. w(6) Ifwincludes only the dissipation within the cavity itself, due tothe resistance ofthe walls and todielectric losses ininsulators within the cavity, etc., theQdefined above iscalled theunloaded Q,usually written Qo. Ifwincludes, inaddition, energy dissipated inexternal circuits coupled tothe cavity, weobtain instead the loadedQ,orQL, which of course can never exceed Qo. 
 These aregas-discharge devices ofavery special sort. The gas discharge isstarted bythe high-power Rotatingantenna —1 4! 1==1hr!!lI1 High.Scanner base+ voltaga pulses) J tRfechopulses /’JMixer Echol:-feceyI-fechopulses Video l-f amplifier amplifier tEchopulsesIJ’ o Angledatafromscanner Indicator zwming pUIS.Sindicating imtant oftransmission (i.e.Zerorange) FIG. 1.4.—Block diagram ofasimple radar. 
 CALLY SET  D" BELOW FULL SCALE TO PREVENT OVERLOAD AS A RESULT OF COMPONENT TOLERANCE VARIATIONS 4YPES  OF  3IGNALS  6ARIOUS TYPES OF SIGNALS ARE OF INTEREST IN DETERMINING  DYNAMIC 
 Begin with the simple calculations.     Find: Radar parameters?  . Radar System Engineering  Chapter 12 – Selected Radar Applications  158     € λ= Pt= Pmin= GT= GR= GI= Aeff= τ= PRF = B= θHB= ψHB= POD = PFA =   13.4 Phased -Array Radar   Phased arrays are groups of antenna with the possibility to electronically steer the directivity  (beam forming). 
 Array con - figurations for performing deterministic RF nulling using amplitude and phase weights  and phase-only weights at each element are shown in Figure 13.39. Deterministic RF nulling using amplitude and phase control at each element pro - vides better performance than phase-only nulling. Deterministic RF nulling can be  accomplished by using perturbation techniques to generate the weights at each element  that will produce the antenna pattern with nulls.102 With perturbation techniques, first  the weights at each element are computed to generate the original antenna pattern with - out nulls. 
 Marchais, and E. Normant, Air and Spaceborne Radar Systems:   An Introduction.,  Chapter 2, Norwich, NY: William Andrew Publishing, LLC, 2001.  7. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo.  GROUND ECHO  16.436x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 s 0 decreases rapidly as the sun melts the top layer. 
 Several algorithms for SAR data-focusing are well established and used by space agencies. Such algorithms are model-based, i.e., the radiometric and geometric information about the speciﬁc sensor must be well known, together with the ancillary data information acquired on board the platform. In the development of low-cost and lightweight SAR sensors, to be used in several application ﬁelds, the precise mission parameters and the knowledge of all the speciﬁc geometric and radiometric information about the sensor might complicate the hardware and software requirements. 
 = ht: an "equivalent noisetemperature"can be obtained rora laser  receiver. At the CO2 laser wavelength of 10.6 µm, I;.= 1360 K and at 1.0 µm wavelength  1;. = 14.400 K. 
 . £n°ÓÈ  2!$!2 (!.$"//+  AND  ST A J J R T T     EXP;    = 
 May.1959. 30.Dunn,J.H.,andD.D.Howard: TargetNoise.chap.28of"RadarHandbook," M.I.Skolnik (ed.), McGraw-Hili BookCo.,NewYork,1970. 31.Locke.A.oS.:"Guidance," D.VanNostrand Company. 
 Ó°xn  2!$!2 (!.$"//+  4HE MISMATCH LOSS HAS NOW BEEN REDUCED TO  D" &INALLY  THE COMPLETE DOPPLER  FILTER BANK IS SHOWN IN &IGURE  4HIS FILTER BANK COULD BE  AUGMENTED WITH ADDI 
 &INE    n  r   r       %XPERIMENTAL-/$%8 '-4)  6ERY (IGH 2ESOLUTION  r   r  p  !DVANCED ,AND /BSERVATION 3ATELLITE  *!8!  *APAN e  $ISCUSSED LATER IN THIS SECTION. £n°£Ó  2!$!2 (!.$"//+  *IAN"ING 
 Proper inputs to the model, corresponding to the most relevant operational  conditions for the real system, can be generated by the same computer programs. The  outputs obtained are compared with some reference values (expected or theoretical)  to assess system performance. When random inputs are provided, a number of statisti - cally independent trials are performed to achieve a significant sample of the output  values from which reliable statistics can be estimated. 
 Jan.25.1977. 99.Casner. P.G.,andR.J.Prcngaman: Integration andAutomation ofMultiple Co-located Radars, Jllfernat;OIIllI (OIlfl'Tl'lIC!' RADAR-n. 
 A single lightning stroke radiates considerable RF noise  power. At any one moment there are an average of 1800 thunderstorms in progress in different  parts of the world. From all these storms about 100 lightning flashes take place every second.53  The combined effect of all the lightning strokes gives rise to a noise spectrum which is  especially large at broadcast and short-wave radio frequencies. 
 W. Rihaczek, Principles of High-Resolution Radar , New York: McGraw-Hill Book Company,  1969, chap. 8. 
 F Region: This is the highest-altitude region of interest for sky-wave prop- agation, and it is also the region of greatest electron density. In the daylight hours there may be two components that should be recognized, especially in summer. The Fl region lies between 130 and 200 km and, like the E region, is directly dependent upon solar radiation; it reaches maximum intensity about 1 h after lo- cal noon. 
 in this case the duplexer, is  iti~ertcd into tlie tsansrnissiori line. 'Tlic precise value of the i~isertiorl loss depends to a large  exte~it on tile particular design. For a typical duplexer it might be of the order of 1 dB. 
 This graph is from Billingsley9 and the additional points indicated by an  asterisk are from Ward.14 Figure 2.17 a shows a PPI display of all clutter observed with a surveillance radar with  a 1.3° by 2- µs resolution cell in the mountainous region of Lakehead, Ontario, Canada.  (The PPI range is set for 30 nmi.) Clutter that exceeds the minimum-discernible signal  (MDS) level of the radar by 60 dB is shown in Figure 2.17 b.FIGURE 2.16  Distribution of reflectivity for ground clutter typical of heavy clutter at S band  (after D. K. 
 Kramer, and R. L. Fante, “Efficient wideband jammer  nulling when using stretch processing,” IEEE Trans ., vol. 
 —E-scoPe. Lines of getare correlated inthe two displays onequal height areshown dotted. thebasis ofrange and azimuth position. 
 Large reflections often occur at scan angles  just prior to the emergence of a grating lobe into real space, but in some instances such  reflections may occur at smaller scan angles. The description of the impedance variation given above made no reference to the  feed network or the phase shifters and assumed that the only coupling between ele - ments is via the radiating aperture. The coupling coefficients would be measured, and  by superposition, the phased-voltage contributions from every element in the array  (or at least those in the immediate vicinity) would be added vectorially to produce  the voltage reflected back toward the generator. 
  
 POLARIMETRIC 4ERRA3!2 
 13.6, sometimes Fig. 13.8, and sometimes neither; so the straight lines in these figures cannot be taken too seriously. In fact, it appears that there is no simple functional dependence ofUPWINDFREQUENCY: 15GHz ANGLEOFINCIDENCE: 40° H POLARIZATION VPOLARIZATION . 
 2.35  Pattern Factor  ....................................................  2.35  Reflection Coefficient  .........................................  2.36 Total Phase Difference  ...................................... 
 AP-17, pp. 363-365, May, 1969.  155. 
 If the bandwidth  is limited by external factors to a value B, the spectrum which produces the largest /I, and  llence the most accurate range measurement, would be one which crowded all its energy at the  two ends of the batid; that is,  where .fo is the carrier frequency and 6(x) is the delta function. The corresponding time  waveform consists of two sine waves at frequencies fo +_ 812. This is the two-frequency CW  radar waveform discussed in Sec. 
 Fleet," 14th ed., Naval Institute Press, Annapolis, Md., 1987, chap. 29, Electronic Systems. 19. 
 The effects of non-free-space propagation on  the radar are of three categories: (1) attenuation of the radar wave as it propagates through the  earth's atmosphere, (2) refraction of the radar wave by the earth's atmosphere, and (3) lohe  structure caused by interference between the direct wave from radar to target and the wave  which arrives at the target via reflection from the ground.  In general, for most applications of radar at microwave frequencies, the attenuation in  propagating through either the normal atmosphere or through precipitation is usually not  sufficient to affect radar performance. However, the re.fle~tion of the radar signal from rain  (clutter) is often a limiting factor in the performance of radar in adverse weather. 
 Finn27 investigated the problem of the reference cells spanning two continuous dif - ferent “noise” fields (e.g., thermal noise, sea clutter, etc.). On the basis of the samples,  he estimated the statistical parameters of the two noise fields and the separation point  between them. Then, only those reference cells that are in the noise field containing  the test cell are used to calculate the adaptive threshold. 
 Noise introduced by the  front end increases the radar noise temperature, degrading sensitivity, and limits the  maximum range at which targets are detectable. Front-end saturation on strong signals  may limit the minimum range of the system or its ability to handle strong interference.  Finally, the front-end spurious performance affects the susceptibility to off-frequency  interference. 
 Under certain operating  conditions, the prediction of the median time to failure (MTTF) for some RF transis - tors can exceed 1,000 years. ● Transistor amplifiers operate at much lower voltages; therefore, power supply volt - ages are on the order of volts rather than kilovolts to avoid the need for large spac - ings, oil filling, or encapsulation. Compared with a high-voltage power supply, a  low-voltage supply uses fewer nonstandard parts and is generally less expensive. 
 theradardesigner shouldstartwiththeuser'srequirements. Foranair-traffic­ controlradarthesemightincludethefollowing: purpose theradaristoserve;typesofaircraft itmustdetect;maximum range,withastatedprobability ofdetection andaverage time between falsealarms;coverage; numberofaircraftexpected withintheradarcoverage; mini­ murnspacing oftargets, whichthendetermines therequired resolution; accuracy oftarget location, ortheaccuracy ofthetargettrajectory ifatrack-while-scan radar;weather andthe environment inwhichtheradarmustoperate, including restrictions imposed bythesiteorthe. Figure 14.10 Photograph of the ARSR-3, air route surveillance radar. 
 BOARD TECHNIQUE INTENDED TO CREATE  ANGLE DECEPTION BY CAUSING A MISSILE SEEKER TO TRANSFER ANGLE TRACK FROM THE TARGET TO A DECOY #ONSEQUENTLY  THE MISSILE GUIDES TOWARD THE DECOY AND AWAY FROM THE TARGET ! SELF 
 DAMPED SYSTEMS MAY GIVE AN APPARENTLY STABLE INDICATION OF THE  TRACK OF A TARGET BUT CAN BE VERY INACCURATE WHEN A TARGET CHANGES HEADING &ROM THE POINT OF VIEW OF SAFETY OF NAVIGATION  THE CHANGE IN HEADING IS OFTEN THE MORE IMPOR 
 359-385, June 1939. 37. MacColl, L. 
 2AO LOWER BOUND 3CHWARTZ  SHOWED THAT WITHIN  D" THE  OPTIMAL VALUE OF - FOR MAXIMUM 0$ IS GIVEN BY   - .   &)'52%  !NGULAR ACCURACY OBTAINED WITH BEAM 
 Natural conditions provide a basis for subsidence and make subsidence possible. Human activities are driving factors and make subsidence happen. Moreover, subsidence information could be used in disaster prevention, urban planning, and hydrological modeling. 
 These crystal mixers are very efficient, but are apt to  burn out easily and lose sensitivity if excessive voltage  is applied to them. For this reason special precautions  must be taken with centimetric radar when using a  common aerial for transmission and reception to ensure  that none of the transmitted signal energy is accidentally  passed to the receiver feeders. Diode mixers can with-  stand a greater overloading, and do not need to be so  elaborately protected against the transmitter signal  voltage. 
 Substituting the gam of the cosecant-squared antenna  [Eq. (2.46)] into the simple radar equation gives  p _ P,G2(<j,0) csc4 <j,l2<J csc4 <j,  r -(41t)3 csc4 <Po R4 = K 1 -R4 (2.47)  where K 1 is a constant. The height h of the target is assumed constant, and since csc <j, = R/h,  the received power becomes  (2.48)  where K 2 is a constant. 
 Radar Resolution   The target resolution of radar is its ability to distinguish between targets that are very close in either  range or bearing. Weapons -control radar, which requires great precision, should be able to  distinguish between targets that are only yards apart. Search radar is usually l ess precise and only  distinguishes between targets that are hundreds of yards or even miles apart. 
 GIGo=(I+~i~)~xpr=:51)==:T+'3i'+'Z l Notethattherelativereduction ingainisindependent ofthenumberofelements anddepends onlyonthefraction ofelements thatareoperative andthemeansquarevalueoftheerrors. Whenp..=Iandt1=0,theexpression is,forsmall-phase errors,similartothatofEq.(7.30) forthecontinuous aperture. Inaddition toraisingthesidelobe level,random phaseandamplitude errorsinthe aperture distribution causeanerrorintheposition ofthemainbeam.Rondinelli 110hasshown thatforauniform amplitude distribution acrossanMbyMsquarearray,thestatistical rms heampointing erroris (8.29) where (j=rmsvalueofnormalized errorcurrentassuming Rayleigh distributed errors k=2rr/). 
 The Schottky-barrier diodes have had lower noise figures and lower  flicker noise than conventional point-contact diodes, but the silicon point-contact diode has  Iiati better burnout properties. An integral part of the mixer is the local oscillator. The IF  amplifier is also of importance in mixer design because of its influence on the overall  noise-figure. 
  #)# FILTER FOLLOWED BY A DECIMATE 
 Barker Codes can vary in length from 2 - 13  bits, providing a corresponding compression ratio  of 2 - 13.  The compression is achieved in the receiver by sensing the  auto-correlation of the Barker sequence within the detected  pulse.     Figure 8. 
 , vol. AES-15, pp. 696–708, 1979. 
 23, pp. 282-332, 1944,  and vol. 24. 
 Interestingly, the bandwidth of the spec- trum remains relatively constant. f (Hz) FIG. 13.14 Qualitative behavior of doppler spectra of sea clutter looking upwind at low grazing angles. 
 143. Sensors 2019 ,19, 2921 5.1.2. Phase Error due to the Di ﬀerence in Phase Distortion of the SAR Images The defocusing can cause phase distortion in SAR images. 
 J. Gersten: AN/TPS-59 System, IEEE 1975 International Radar Conj., April 21-23,  1975. pp. 
 The received power is simply the integral under the curve and is given by Pr = Js(f)tf = fs(v)dv (23.29)Transmitted power (klystron) Pulse width Range (doppler mode) Unambiguous velocity (doppler mode) Range (nondoppler mode) Clutter rejection Beamwidth System sensitivity700,000 W 1.6,4.8 JJLS 230km ±50m/s 460km 5OdB 1° (-8 dBZ at 50 km) . FIG. 23.2 The doppler spectrum. 
 W. Crispin, A. L. 
 SPACE WAVELENGTH  KC   CUTOFF WAVELENGTH OF GUIDE &)'52%   4WO ADJACENT ELEMENTS COUPLING TO  ANOTHER ELEMENT IN THE SAME ROW . £Î°ÓÈ  2!$!2 (!.$"//+  !DDITIONAL SCAN ANGLES MAY BE SIMULATED BY EXCITING OTHER MODES 4HE WAVEGUIDE  DIMENSIONS ARE CHOSEN SO THAT A RADIATING ELEMENT OR ELEMENT PLACED IN THE WAVEGUIDE  SEES MIRROR IMAGES IN THE WALLS OF THE WAVEGUIDE THAT APPEAR TO BE AT THE SAME SPACING AS THE ARRAY TO BE SIMULATED "OTH RECTANGULAR AND TRIANGULAR ARRAYS MAY BE SIMULATED  AS SHOWN IN &IGURE  4HE IMPEDANCE MEASUREMENTS ARE MADE BY LOOKING INTO A WAVEGUIDE SIMULATOR THAT IS TERMINATED WITH DUMMY ELEMENTS 4HIS IS EQUIVALENT TO LOOKING AT AN INFINITE ARRAY FROM FREE SPACE AT A SCAN ANGLE GIVEN BY %Q  ! MATCHING STRUCTURE  DESIGNED FROM THE SIMULATOR IMPEDANCE DATA  MAY BE PLACED INTO THE SIMULATOR TO MEASURE ITS EFFECTIVENESS 3EVERAL SIMULATOR DESIGNS  RESULTS  AND A COMPLETE DISCUSSION OF THE TOPIC HAVE BEEN PRESENTED BY (ANNAN AND "ALFOUR  4HE  TECHNIQUE IS LIMITED IN THAT ONLY DISCRETE SCAN ANGLES CAN BE SIMULATED 3EVERAL SCAN ANGLES IN BOTH PLANES OF SCAN GIVE A GENERAL IDEA OF THE ARRAY IMPEDANCE&)'52%   !RRAY SIMULATOR TERMINATED WITH TWO DUMMY ELEMENTS &)'52%   2ECTANGULAR 
 LIMITED SPACE 
 L. J.: "Radar Meteorology." University of Chicago Press, Chicago, 1959.  27. 
                        . Óx°Î{  2!$!2 (!.$"//+  3INCE ADDITIONS ARE PERFORMED IN EACH STAGE  THE MAGNITUDE OF EACH OUTPUT STAGE  SAMPLE COULD BE A FACTOR OF TWO OR MORE GREATER THAN THE INPUT SAMPLES )F FIXED 
 .OISE  *AMMER AND 4ARGET 3IGNAL 
 M.r.,andR.Greenwood: AWithin-Pulse Scanning Height-Finder, International COllfer­ ellcemlRadar--PresellfalldFlItllre,lEEConference Publication, no.105,pp.50-55,1973. 105.Schrank, II.F..W.P.Ilooper. andR.S.Davis:AStudyofArrayBeamSwitching Techniques. 
 1This number, l/~N~, iscorrect nomatter how the information isdivided between angular coordinates and range coordinates. The same result can beobtained byobserving that the radar system analyzes hregion inspace bydksecting itinto elements ofvolume, so-called “pulse 1Tobesure, repetition ofpulses from thesame target does give extra information inthat ithelps todistinguish aweak echo from noise. Inthis section, however, sensitivity isnottheprimary concern, andithasbeen tacitly assumed that theechoes appearing ontheradar srreen areallweliabove thenoise background,. 
 FREE RANGE 
 The following section gives details on  estimating this attenuation in commonly encountered conditions. Finally, it is important to note the Z values are of meteorological significance  because they are directly related to cloud properties and actual rainfall rates R as  described later in this chapter. Z values in nonprecipitating clouds as small as   –40 dB Z are of interest for cloud physics studies. 
 2. SWH: 10 percent of the SWH or 0.5 meter (which­ ever is greater),  3. Wind speed: 1.8 meters per second over the range  1 to 18 meters per second. 
 FIXED COORDINATE SYSTEMS 4HE ADDITIONAL WAVE 
 If the noise is not white, Eq. (10.1) may be  modified as discussed later in this section. The filter whose frequency-response function is  given by Eq. 
 Ê " 
 4.15. The weighting factors shown on the feedback  paths apply to the characteristic of Fig. 4.14c. 
  R  3TANDARD DEVIATION OF FILTERED TRACKING STATE SAB A AA B   
 Thusthereliability isbetter.Nospecialtemperature controlisrequired, andit canbepackaged inconvenient size.Thedynamic rangeisgreatersincedigitalMTIprocessors donotexperience thespurious responses whichlimitsignalsinacoustic delaylinestoabout35 to40dBaboveminimum detectable signalleveI.2s(Amajorrestriction ondynamic rangein adigitalMTIisthatimposed bytheAIDconverter.) Inananalogdelay-line canceler thedelay timeandthepulserepetition periodmustbemadeequal.Thisissi~plified inadigitalMTI sincethetimingofthesampling ofthebipolarvideocanbecontrolled readilybythetimingof thetransmitted pulse.Thus,different pulserepetition periodscanbeusedwithoutthenecessity ofswitching delaylinesofvariouslengthsinandout.Theechosignalsforeachinterpulse periodcanbestoredinthedigitalmemory withreference tothetimeoftransmission. This allowsmoreelaborate staggerperiods.Theflexibility ofthedigitalprocessor alsopermitsmore freedom intheselection andapplication ofamplitude weightings forshapingthefilters.Ithas alsoallowed thereadyincorporation ofthequadrature channel forelimination ofblind phases.Inshort,digitalMTIhasallowed theradardesigner thefreedom totakeadvantage of thefulltheoretical capabilities ofdoppler processing inpractical radarsystems. Thedevelopment ofdigitalprocessing technology hasnotonlymadethedelay-line canceler amoreversatile toolfortheMTIradardesigner, butithasalsoallowed theapplica­ tionofthecontiguous filterbankforaddedflexibility inMTIradardesign.Oneofthemajor factorsinthisregardhasbeentheintroduction ofdigitaldevicesforconveniently computing theFouriertransform. 
 BEAM CLUTTER THAT ARE COMPLETELY DISCARDED EXCEPT FOR MOTION COMPENSA 
 If  more than one target is present they cannot be resolved. Even if only one target were present,  the noise from the other range ceHs that do not contain the target .vill interrere with the desired  target signal. The result is a reduction in sensitivity due to a collapsing loss (Sec. 
 BEAM ANTENNASBEAM LIFTED ABOVE THE HORIZON FOR SHORT 
 CESSORS MAY ONLY NEED TO BE RECOMPILED IN ORDER TO  MOVE IT TO A NEW PROCESSOR 4OOLS  CURRENTLY EXIST THAT SYNTHESIZE # OR -ATLAB CODE INTO AN &0'! DESIGN  BUT THESE TOOLS ARE TYPICALLY NOT VERY EFFICIENT 4HE EVOLUTION OF DESIGN TOOLS FOR &0'!S TO ADDRESS THESE PROBLEMS IS AN AREA OF MUCH RESEARCH AND DEVELOPMENT (YBRID 0ROCESSORS  !LTHOUGH IT WOULD BE VERY DESIRABLE TO SIMPLY WRITE # CODE  TO IMPLEMENT A COMPLEX  RADAR SIGNAL PROCESSOR   THE REALITY IN THE EARLY ST CENTURY IS  THAT  FOR MANY SYSTEMS  IMPLEMENTING SUCH A SYSTEM WOULD BE PROHIBITIVELY EXPENSIVE OR INFLICT MAJOR PERFORMANCE DEGRADATION !LTHOUGH THE STEADY INCREASE IN PROCESSOR THROUGHPUT MAY SOMEDAY COME TO THE RESCUE  THE REALITY AT THIS WRITING IS THAT HIGH 
 HORIZON /4(  RADAR &OR THE FORESEEABLE FUTURE  THE FULLY ADAPTIVE ARRAY IE  WITH ADAPTIVITY AT RECEIVING  ELEMENT LEVEL  HAS ONLY THEORETICAL VALUE FOR ANTENNAS WITH A THOUSAND ELEMENTS 4HERE ARE RADARS THAT ARE FULLY ADAPTIVE  BUT THEY HAVE ONLY A LIMITED NUMBER OF ELEMENTS THAT CAN BE ECONOMICALLY HANDLED IN AN ADAPTIVE ARRAY !RRAYS WITH A LARGE NUMBER OF RECEIVING ELEMENTS NEED SOME FORM OF PROCESSING REDUCTION /NE METHOD OF PARTIAL ADAPTIVITY IS TO ARRANGE THE ARRAY ELEMENTS IN SUBGROUPS THAT FORM THE INPUTS OF THE ADAPTIVE PROCESSOR #AREFUL SELECTION OF THE SUBGROUP ELEMENTS IS NECESSARY TO AVOID GRATING LOBES THIS TOPIC IS DISCUSSED IN A FOLLOWING SECTION !NOTHER SIMPLIFICATION OF THE FULLY ADAPTIVE ARRAY IS THE DETERMINISTIC SPATIAL FILTERING  WHERE A FIXED REDUCTION OF THE SIDELOBES IS OPERATED IN THOSE DIRECTIONS OR SOLID ANGLES FROM WHICH THE INTERFER 
 ATING PROFILE WAS DESIGNED TO EXPLOIT A VARIETY OF INCIDENT ANGLES !T THE START OF EACH IMAGING PASS AT HIGH ALTITUDE  THE INCIDENCE WAS SLEWED FROM STEEP NEAR THE POLE  TO SHALLOW IN THE NEIGHBORHOOD OF THE EQUATOR  BACK TO STEEP WHEN APPROACHING THE OPPOSITE POLE 4HIS INCIDENCE VARIATION HELPED TO OFFSET THE LARGE CHANGE IN RADAR RANGE TO THE IMAGED SWATH  BUT IT MEANT ALSO THAT THE RANGE RESOLUTION AS EXPRESSED ON THE SURFACE VARIED AS A FUNCTION OF LATITUDE &OR A CONSTANT RADAR  BANDWIDTH  THE EFFEC 
 (('ol/rles.\' RC·L111(,) computer-controlled multifunction radar.Thevarious functions tobeperformed mustbe efficiently prioritized soasnottoexceedeitherresource. Insearch,themaximum range ofintereststrongly affectsthetimeresource. Intracking, thetargetrangedoesnotusuallylimit thetimeresource sincetherangeisknownandthedwellinterval canbeadjusted accordingly. 
 BY 
 (editor in chief): "IEEE Standard Dictionary of Electrical and Electronic Terms," 2d ed. John  Wiley & Sons. Inc., New York. 
 Attempts to use noise degeneration to  reduce the inherent RF tube noise levels are subject to limitations. In-band spurious  signals can also result from power supply and modulator instabilities. Reduction of Spectrum Amplitude Exceeding (sin x)/x. 
 ii ABOUT THE EDITOR IN CHIEF Merrill Skolnik  was Superintendent of the Radar Division at the U.S. 
 1 f r lie false-alarnl (irrle were increased from 15 rnin to 24 h, the signal-to-noise  ratio would he iricreascd to 15.4 dI3. If the false-alarm tinie were as high as 1 year, the required  sigllal-to-rioisc ratio wot~ld Ijc 16.2 dl3.  2.6 INTEGRA'TION OF RADAR PULSES  'I'lic r cli~tiorisliil~ t)ctwcct~ tlic siglial-to-lioisc iatio, tlic probability ofdctcctioti, aucl tltc 11l.oI1-  ability of false alarrn as giver1 in Fig. 
 DIMENSIONAL ARRAY MAY BE CALCULATED BY SUMMING THE  VECTOR CONTRIBUTION OF EACH ELEMENT IN THE ARRAY AT EACH POINT IN SPACE &OR AN ARRAY  SCANNED TO A DIRECTION GIVEN BY THE DIRECTION COSINES COS  @XS AND COS @YS  THE ARRAY FAC 
 For a scanning weather radar, it takes about four  beamwidths of scanning after the transmitter starts pulsing before clutter attenuation  reaches 50 to 60 dB. Second, if the input clutter signal reaches the limit level in the  IF receiver, there will be a significant transient increase of clutter residue. One of the  elliptic filters employed in the original TDWR radar is used as an example. 
 Optimizing the molecular content of the FET  channel for best performance is sometimes referred to as bandgap engineering . The  challenge for the device engineer is to develop a transistor that supports the highest  voltage/current operation while demonstrating the best high frequency gain.FIGURE 11.7  Performance space of commercially available silicon power transistors FIGURE 11.8  Performance space of commercially available silicon power transistors ch11.indd   13 12/17/07   2:25:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 &- RANGING  DOPPLER CORRELATION WINDOW  4&2   OVERALL !LERT#ONFIRM FALSE REPORT TIME 4HE - 
 Delays due to water-vapor in the atmosphere are vari - able down to scales of several hundred kilometers (and much smaller when traversing  a storm front). Standard practice is to measure the integrated water vapor contribution  in the vertical column below the altimeter by a microwave radiometer, for which two  or three frequencies are required. Measurement errors are dominated by the accuracy of orbit height determination  and by the intrinsic precision of the instrument. 
 15.58  I and Q Balance Requirements  ..........................  15.59  Timing Jitter  .......................................................  15.60 Linearity  ............................................................ 
 Elimination of false positives using optical ﬂow. Change areas are moved along the ﬂow direction in the reference image change map. Moved areas (shown in red) from the reference image are overlaid onto the mission image change map. 
         B    WHERE %   ANALOG VOLTAGE  .   NUMBER OF BINARY DIGITS  BI   STATE OF ITH BINARY DIGIT  K   QUANTIZATION VOLTAGE /FFSET BINARY IS AN ALTERNATE CODING SCHEME IN WHICH THE MOST NEGATIVE VALUE IS  REPRESENTED BY ALL ZEROS AND THE MOST POSITIVE VALUE IS REPRESENTED BY ALL ONES :ERO IS REPRESENTED BY A MOST SIGNIFICANT BIT -3"  OF ONE FOLLOWED BY  ALL ZEROS 4HE REPRE 
 7. 24. D. 
 x°Îä  2!$!2 (!.$"//+  LOOKS IN EACH BEAM CREATE AS MANY AS  INDEPENDENT LOOKS 4HE  SHORTEST RANGE AT THE  BOTTOM OF THE ELEVATION SCAN USES A SHORT PULSE WITH NO PULSE COMPRESSION AND A MUCH  HIGHER 02&  BUT THE SAME NUMBER OF LOOKS 4HE PULSES IN A  4/4 ARE ALL THE PULSES THAT  ILLUMINATE A SINGLE SPOT FROM THE OVERLAPPING BEAMS %ACH OVERLAPPING BEAM MUST BE COMPENSATED FOR THE ANTENNA LOOK ANGLE BEFORE THE BEAMS CAN BE SUMMED FOR A TERRAIN HEIGHT ESTIMATE FROM ALL THE BEAMS  4HE RADAR CROSS SECTION OF THE TERRAIN COULD BE  QUITE LOW EG  SNOW 
 30. P. J. 
 K. F.. Huecks. 
 Brenner, A.R.; Ender, J.H.G. Demonstration of advanced recon-naissance techniques with the airborne SAR/GMTI sensor PAMIR. IEE Proc.-Radar Sonar Navig. 
 ERROR PHASE DETECTOR IS DETERMINED BY THE RELATIVE PHASE SEE &IGURE   4HE PHASE 
 This  procedure results in a conservative prediction of radar range and has the advantage of simpli-  city. The minimum cross section of typical aircraft or missile targets generally occurs at or near  the head-on aspect.  However, to properly account for target cross-section fluctuations, the probability-  density function and the correlation properties with time must be known for the partici~lar  target and type of trajectory. 
 30.  5. K. 
 POWER SIDE PROVIDES AN IMPEDANCE MATCH TO THE POWER  AMPLIFIER AND MAY BE ADEQUATE BY ITSELF FOR PROTECTING THE RECEIVER )N &IGURE   THE MODULE IS SHOWN AUGMENTED BY A SWITCH THAT CAUSES ABSORPTION OF POWER REFLECTED FROM ANTENNA MISMATCHES AND ALSO GIVES ADDED PROTECTION TO THE  RECEIVER DURING TRANS 
 If the processed (e.g., integrated) receiver output exceeds the threshold (as evidenced by diode current flow), some mechanism is actuated to indicate this fact in an unequivocal fashion. The mechanism could be the lighting of a light, the ringing of a bell, or more generally the setting of a bit to 1 in a binary data channel wherein a O corresponds to no signal. Various additional consequences may then automatically ensue. 
 TION ON 3!2 !42 v  )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS   VOL   NO     PP   *ANUARY   2 + 2ANEY  h3YNTHETIC APERTURE IMAGING RADAR AND MOVING TARGETS v  )%%% 4RANSACTIONS OF  !EROSPACE AND %LECTRONIC 3YSTEMS  VOL !%3 
 The received field may  be represented by   E Er t e RS =−jkR (16.31) where  Er vr hrE E=   and Et vt htE E=    and  SS S S S=  vv vh hv hh (16.32) In the usual reciprocal media, Svh = Shv. Since the choice of a phase reference is  arbitrary, there are then three independent magnitudes (| Svv|, |Shh|, |Shv|), but only two  independent phases ( ∠Shh, ∠ Shv). These quantities can be used to describe the proper - ties of the polarized part of the echo from a target. 
 LIGHT BEAMS    MULTIPLE BEAMS  AND   TIME 
 Normal incidence as shown yields the largest echo, but oblique incidence  echoes and scattering from the meteor “head” are also observed. Figure 20.16 compares  a simple predictive model with measurements, confirming that the observed behavior is  understood and thus can be taken into account in radar design and operations. ch20.indd   38 12/20/07   1:16:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 TO 
 In  general, the number of implemented receiving channels is mainly a matter of cost.  It has been argued that radar systems with a number of adaptive dof of a few tens  are already in operation in the microwave band; the number of adaptive dof may be  more in the over-the-horizon (OTH) radar. For the foreseeable future, the fully adaptive array (i.e., with adaptivity at receiving  element level) has only theoretical value for antennas with a thousand elements. 
 The quality of the radar image can be exceptionally good, although correct  understanding normally requires joint interpretation by the archaeologists and radar  specialists. Since 1990, the Square Geophysical Survey Project, under the auspices of  the National Museum of Scotland and the Glasgow Museums, have been carrying out  geophysical and archaeological surveys at Square in Egypt. Square forms part of the  necropolis of the ancient Egyptian capital city of Memphis. 
 8.3. General Identification Systems, IFF.—The discussion ofthis chapter isconfined almost entirely tothe use ofbeacons for various navigational problems and for identification systems ofsomewhat. 252 RADAR BEACONS [SEC. 
 IEEE Truns.,  vol. MTT- 18, pp. 1 1 19- 1 124, December, 1970. 
 OF 
 123. Barton, D. K.: Land Clutter Models for Radar Design and Analysis, Proc. 
 248, Oct. 20,  1952.  74. 
 ", Ê 
  ANTENNA  A  COMPARED WITH THE COSECANT 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 FIGURE   16. 
 These losses  are very real and cannot be ignored in any serious prediction or radar performance. The loss  due to the integration of many pulses (or integration efficiency) has already been mentioned in  Sec. 2.6 and need not be discus·sed further. 
 A., and W. G. Howell: Ferrite Quarter Wave Type Absorber, Conference Proceed-  ings Military Microwave, London, 1978, Microwave Exhibitions and Publishers Ltd., pp. 
 9  Range Resolution  ................................ ................................ ................................ 
 TO 
 All other  trade  names  referenced  are  the service  marks,  trademarks  or registered  trademarks  of their respective  companies.  . 
 NOISE RATIO 0HASE MONOPULSE USES A  DELTA OR DIFFERENCE BEAM  .   05,3% $/00,%2 2!$!2   {°£Î WHICH IS ESSENTIALLY FORMED BY DIVIDING THE APERTURE INTO TWO HALVES AND SUBTRACTING  THE CORRESPONDING PHASE CENTERS -ONOPULSE BEAMS  DELTA 
 6 CURRENT 
 4.29 are given in the  caption.  MTIANDPULSE DOPPLER RADAR131 Thiswouldapply10thecoholockingortothephasechangeintroduced byapoweramplifier. Aphasechangepulse-to-pulse of0.01radiansresultsinanimprovement-factor limitation of 40dB.Thelimitstotheimprovement factorimposed bypulse-to-pulse instability arelisted below:A.46.47 Transmitter frequency Staloorcohofrequency Transmitter phaseshift Coholocking Pulsetiming Pulsewidth Pulseamplitude(rrl\frrz (2rrl\fTrz (l\¢rz (l\¢rz rZj(l\t)Z2Br rZj(l\rfBr (Ajl\A)! wherel\(=interpulse frequency change,r=pulsewidth,T=transmission timetoandfrom target.l\¢=interpulse phasechange,M=timejitter,Br=time-bandwidth productofpulse compression system(=unityforsimplepulses,)l\r=pulse-width jitter,A=pulseamplitude, l\A=intcrpulse amplitude change.Inadigitalsignalproccssor theimprovement factorisalso limitedbythequantization noiseintroduced bytheAjDconverter, aswasdiscussed in Sec.4.5.Thedigitalprocessor, however, doesnotexperience degradation duetotimejitterof thetransmitted pulsesincethesystemclockcontrolling theprocessor timingmaybestarted fromthedctected rfenvelope ofthetransmitted pulse. 
 Too large a number cannot be profitably  paralleled because of losses that occur on combining. The gain of a transistor is only of the  order of 10 dB, so that several stages or amplification are necessary to achieve a reasonable  total gain. t\n L-band module using eight transistors (four paralleled in the final stage, two  paralleled in the penultimate stage, and t.wo series driver stages) might have a peak power  greater than 200 W, 0.1 duty cycle, 200 MHz bandwidth, a gain of 30 dB, and an efficiency  better than 30 percent.31 (When examining the claims of power from solid-state devices, it  should be kept in mind that the greater the junction temperature the less the life of the device. 
 Conf. Radar  ICR-91 , China Institute of Electronics, 1991, pp. 138–141. 
 Theconstant Kistheaverage gainofthedelaylinecanceler (K=2for atwo-pulse canceler and6forathree-pulse canceler.) Thecombined improvement factorfor DPCAandthesibelobe limitation is I=+._--- ItotaII.,IDI'CA(4.41) Adaptive arrayantennas maybeemployed tocompensate forplatform motion inan 1\MTIradar.61Thefullarrayisilluminated ontransmission sothatthetransmit patternisthe samefrompulsetopulse.Onreceive, thearrayismadeadaptive byobtaining aseparate outputfromeachelement. Eachelement outputcanbeweighted separately andtheoutputs addedtogether toformanaperture illumination function thatadaptively permits motionof theantenna phasecentersoastocompensate forplatform motion. Adaptive loopsarealso usedinthedelay-line canceler tocontrolthedoppler response ofthecanceler aswellasthe antenna angular response. 
 However, one may require a much larger number of detections when the radar has  the flexibility of an electronic scan that can place many detection opportunities in  a short time interval. 2. Backward-tracking or “batch” algorithms  consider all the detections simultane - ously, attempting to match the detections to a “target-like” pattern. 
 UTES &IELD RESEARCH  HAS CLEARLY DEMONSTRATED THAT A FEW MINUTES ADVANCE WARNING  USING DOPPLER RADAR CAN BE ACHIEVED /PERATIONAL MICROBURST DETECTION RADARS USE THIS AUTOMATED DETECTION ALGORITHM WITH HIGH PERFORMANCE GROUND CLUTTER MITIGATION TECH 
 Also, it has been notedt that the number of actual data points in Fig. 2.2 may be too few on which to base a good estimate of the optimum. Consequently, it is possible that the value of a for human observation of visual displays is much closer to 1 than was deduced by Lawson and Uhlenbeck. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 false targets, (5) maintenance of target tracks, (6) counteraction of ESM, and (7) radar  system survivability.3 There are two broad classes of ECCM: electronic techniques (Section 24.6–24.9)  and operational doctrines (Section 24.10). 
 Metal-plate lens.49- An artificial dielectric may be constructed with parallel-plate wave-  guides as shown in Fig. 7.19. The phase velocity in parallel-plate waveguide is greater than that  in free space; hence the index of refraction is less than unity. 
 Accordingly, optimization of the allocation of resources becomes a critical issue, with  significant implications for the way skywave radars operate. One approach to fitting more tasks into the time available is to partition the radar  transmit and receive arrays, together with the transmitter modules and receivers, so  that when conditions are favorable, the partitions can operate as independent radars  with reduced sensitivity and resolution. For example, the Jindalee and JORN radars  are dynamically reconfigurable as full or half radars. 
 Note that Pra = 1/Tra Bis the probability of false alarm assuming that independent deci­ sions as to the presence or absence of a target are made B times a second. As the radar scans hy  a target it receives n pulses. If these n pulses are integrated before a target decision is mad<.!,  then there are 8/n p~ssible decisions per second. 
 Hansen (ed.), Academic Press, N.Y., 1966, chap. 3.  78. 
 Behind the smooth, black plastic horns is hidden a  modified airplane Radar.  The distance to the approaching vehicle and the braking distance are  indicated on the instrument panel.     Figure 13.9  Radar in the 1959 Cadillac Cyclone. 
 MARIZED IN 4ABLE . n°ÎÈ  2!$!2 (!.$"//+  ** 
 Soame, T. A., and D. M. 
 At higher elevation angles, as might be viewed from  aircraft, the cross sections of ships might be considerably less than at grazing incidence,  perhaps by an order of magnitude. When no better information is available, a very rough order  of magnitude estimate of the ship's cross section at other-than-grazing incidence can be had by  taking the ship's displacement in tons to be equal to its cross section in square meters. The  average cross section of small pleasure boats 20 to 30 ft in length might have a radar cross  section in the vicinity of a few square meters at X band.68 Boats from 40 to 50 ft in length  might have a cross section of the order of 10 square meters. 
 317-328, October, 1963.  70. Caspers, J. 
 Crisp, D.J. A ship detection system for RADARSAT-2 dual-pol multi-look imagery implemented in the ADSS. In Proceedings of the 2013 International Conference on Radar, Adelaide, Australia, 9–12 September 2013; pp. 
 DOPED  LOW 
 L., and A. W. Rudge: Adaptive Control of a Flexible Linear Array, E1ec.rrotlic.s  Lerters, vol. 
 AROUND CLUTTER ECHOESAS CAN AN AMPLIFIER TRANS 
 RadclifTe: Pulse Compression and Signal Processing, IEEE Cot$ Publica-  tion No. 105, " Radar-Present and Future," Oct. 23-25, 1973, pp. 
 Precipitation. and Terrain. Proc. 
   2%&,%#4/2 !.4%..!3   £Ó°Ç 2EFLECTOR TAPER IS OFTEN APPROXIMATED BY A RADIAL AMPLITUDE DISTRIBUTION   GR      
 Incorporating the effect of filter weighting, the improvement factor for a doppler  filter is given by37  I KA A A n m Tn nN n m c( ) exp ( )=   − −=− ∑ 012 2π σ2 2 01 01 2 { } − [ ] =− =− ∑∑ cos ( ) πK n m N mN nN (4.5) ch04.indd   17 12/20/07   4:52:39 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 Mostradarsituations areoftoocomplex anaturetowarrantobtaining comrkk data.Amoreeconomical method toassesstheeffectsofafluctuating crosssection isto postulate areasonable modelforthefluctuations andtoanalyzeitmathematically. Swerling37 hascalculated thedetection probahilities forfourdifferent fluctuation modelsofcrosssection. Intwoofthefourcases,itisassumed thatthefluctuations arecompletely correlated duringa particular scanbutarecompletely uncorrelated fromscantoscan.IntheolhertwocaSl:S,thl: fluctuations areassumed tobemorerapidanduncorrelated pulsetopulse.Thefourtluctua­ tionmodelsareasfollows: Case1.Theechopulsesreceived fromatargetonanyone scanareofconstant amplitude throughout theentirescanbutareindependent (uncorrelated) fromscantoscan.This assumption ignorestheeffectoftheantenna beamshapeontheechoamplitude. 
 own devices, thecircuit will come toequilibrium with VIonand Vjoff. When animpulse ofthe correct polarity isapplied tog,ortog,,the regenerative action cuts offVIand turns V2full on. Grid glthen rises until thecutoff point isreached, when theregeneration reverses and the cycle iscompleted with the original condition restored. 
 160. Malagisi, C. S.: Microstrip Disc Element .Reflect Array, IEEE EASCON '78 Recunl, pp. 
 (See the third row of plots  in Figure 4.20.) 3. With the reduced SNR, determine the new Pd as a function of ambiguous range  within the IPP from the uneclipsed detection curve. 4. 
 Unfortunately, most such systems are uncalibrated or poorly calibrated, so the results  are somewhat dubious, even on a relative basis, when images are produced on dif - ferent days. Relative calibration has been introduced into some systems.20,28,31,102–104  Absolute calibration, which also serves as relative calibration in some cases, can be  achieved by using strong reference targets, with the active radar calibrator (ARC)  repeaters especially suitable.85,105 Another approach that has been used is to measure  scattering from reference areas with a ground-based or helicopter system that is well  calibrated and to compare the images to these measured values.102,106FIGURE   16. 20 Basic block diagram of an FM-CW scatterometer RF section FIGURE   16. 
 For sliding spotlight SAR system, the azimuthal temporal variation of beam central incident and squint angle are considered to be a modiﬁcation into the original model. Here we use the penetration point at the edge of the phase screen as a reference, then the squint angle ϕand incident angle θare expressed as⎧ ⎪⎪⎨ ⎪⎪⎩ϕ(m)=θsq0+kωΔxa·m VIPP θ(m)=arccos/braceleftbigg cos(θi0)·cos/parenleftbigg θsq0+kωΔxa·m VIPP/parenrightbigg/bracerightbigg (18) where Δxa=VIPP/PRF is the sampling distance of ionospheric phase screen at the azimuth direction and the VIPP=Re·Vg/slashbig(Re+Hiono)·sin(θi)is the velocity of the IPP , where Reis the radius of Earth. 4.3. 
 RELATION OF CLUTTER WITH  SAY  A SHIPS ANEMOMETER READINGS IS OFTEN INCONSISTENT !ND ALTHOUGH THE STATE OF AGITATION OF THE SEA SURFACE  SEA STATE  APPEARS TO HAVE A STRONG  EFFECT  IT IS A SUBJECTIVE MEASURE AND ITS RELATION TO PREVAILING LOCAL WINDS IS OFTEN UNCERTAIN -OREOVER  IT HAS BEEN FOUND THAT THE TEMPERATURES OF THE AIR AND THE SEA SURFACE CAN AFFECT THE WAY IN WHICH MEASURED WIND SPEED IS RELATED TO THE GENERATION OF CLUTTER 
 Given a MIMO conﬁguration consider a target located in r=reat a distance rfar away respect to the system extent; the time of ﬂight τmlthat an electromagnetic signal takes to go from the m-th transmitter to the target and come back to the l-th receiver is approximately: τml∼=2 c/bracketleftbigg r−/parenleftbiggxm+yl 2/parenrightbigg ·e/bracketrightbigg ; (1) that is equivalent to transmit and receive a signal from a unique antenna placed in the virtual phase center placed in (xm+yl)/2. Therefore, transmitting alternately from every transmitter and receiving alternately from every receiver, it can be generated a virtual array with N=nTX·nRXelements placed in the MIMO virtual phase centers. It can be noticed that, given a MIMO conﬁguration, the dual one with transmitter and receiver swapped, generates the same phase centers positions. 
 The aperture illumination that maximizes the slope of the difference pattern is  the linear illumination function with odd symmetry about the center of the aperture.23 Not  only do both of these aperture illuminations produce patterns with relatively high sidelobes,  but they cannot be readily generated by the simple four-horn feed. Independent control of the  sum and the difference patterns is required in order to obtain simultaneously the optimum  patterns.  The approximately "ideal" feed-illuminations for a monopulse radar is shown in  Fig. 
 Murakami, T., and R. S. Johnson: Clutter Suppression by Use of Weighted Pulse Trains, RCA Rev.,  vol. 
     "%  "   &)'52%   0REDICTED DISTRIBUTION OF EFFECTIVE 2#3 FOR THE !ERMACCHI -"( TRAINER JET  AIRCRAFT VIEWED NOSE 
 IGNATION 732 4HE NUMBER FOLLOWING THE DESIGNATION IS THE YEAR THE RADAR WENT INTO SERVICE 4HUS 732 
  SIN  SIN   ;COS  SINRR RR Q Q =  WHERE DR IS THE RELATIVE PERMITTIVITY  D`  
 If the target falls in the sidelobe clutter region, the range performance will be degraded, since the total power (system noise plus clutter) with which the target must compete is increased. The foregoing discussion can be applied to the sidelobe clutter region, however, by interpreting R0 as the range where the signal is equal to sidelobe clutter plus systemCASE abCdeMINIMUMNUMBER OFDETECTIONSREQUIRED 13133NUMBER OFINTEGRATIONPERIODSPERDWELL 28153CASE . noise.48"50 The CFAR loss may also be higher owing to the increased variability of the threshold when the clutter varies over the target detection region. 
 Pulse compression might be applied to  each of the individual pulses of the burst for better range resolution, and amplitude weighting  of the pulse burst might be used to lower the doppler sidelobe level to improve the detection of  small doppler-shifted target echoes close in frequency to large clutter echoes.  Stretch is a technique related to pulse compression that permits an exchange of signal-  time duration for signal band~idth.~~.~~ Its advantage is that high range-resolution can be  obtained with wideband transmitted signals, but without the usual wideband processing circ-  uitry. However, only a portion of the range interval can be observed in this manner. 
 4.17 is also provided. The performance with  eclipsing and range gate straddle loss with the use of 50% overlapped range gates is shown.120% duty, 5 RG/IPP, PFA = 1e-006, Npdi = 1, Marcum Target 0.9 0.8 0.7 0.6Probability of Detection0.5 0.4 0.3 0.2 0.1 010 11 12 13 14 Uneclipsed Signal-to-Noise Ratio (dB)15 16 17 18 19 20w/o Eclipsing and RG Straddle w/ Eclipsing and RG Straddle (Approx.) w/ Eclipsing and RG Straddlew/ Eclipsing and RG Straddle (50% Overlap) ch04.indd   43 12/20/07   4:53:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 17.12. The d-ccomponents can beremoved intheway explained inconnection with Fig. 17.11. 
 R. K.: Ground Echo, chap. 25 of" Radar Handbook," M. 
 (/2):/. 2!$!2   Óä°£x DYNAMOS  RESULTING IN AN UPWARD DRIFT OF THE IONOSPHERIC PLASMA AND ITS SUBSEQUENT  DESCENT ALONG THE GEOMAGNETIC FIELD LINES 4HE RESULTING ELECTR ON DENSITY DEPLETION AT  THE EQUATOR AND ROUGHLY SYMMETRIC ENHANCEMENTS IN THE VICINITY OF ^  n .3 LATITUDE  IS KNOWN AS THE  !PPLETON OR  EQUATORIAL ANOMALY "ESIDES CAUSING ERRORS IN ESTIMATED  TARGET RANGE AND BEARING  THE TILTED IONOSPHERIC hREFLECTING SURFACEv NEAR THE EQUATOR CAN SUPPORT SCATTERING OF INCIDENT RADIOWAVES INTO LOW 
 Em'elope detector-optimum-detector law.Thefunction oftheenvelope detector istoextract themodulation andrejectthecarrier.Byeliminating thecarrier,allphaseinformation islost andthedetection decision isbasedsolelyontheenvelope amplitude. Itwillberecalled that mostoftheanalysis oftheradarequation inChap.2wasbasedontheenvelope detector. Theenvelope detector consis~sofarectifying element andalow-pass filtertopassthe modulation frequencies buttoremovethecarrierfrequency. 
 , . ) is the Marcum Q function and PFA is the prescribed probability of false alarm. It is also shown that the set of weights of Eq. 
 Atlas, R. E. Rinehart, and J. 
 The klystron amplifier has been an important RF power source for  many radar applications. As mentioned, it is capable of high average and high peak  power, high gain, good efficiency, stable operation, low interpulse noise, large band - width at high power; and being an amplifier, it can work well with the frequency  and phase modulated waveforms needed for pulse compression. Klystrons have oper - ated at frequencies from UHF to millimeter wavelengths and have found use in such  diverse applications as airport surveillance radars where the average powers might be  more than one kilowatt, in airborne military aircraft where the average power might be  of the order of 10 kW or more, and in long range detection of intercontinental ballistic  missiles where the average power per tube can be greater than 100 kW . 
 WAVE AT THAT hFREQUENCYv THAT WOULD JUSTIFY THE TERM  "RAGG  RESONANCE IN ITS ORIGINAL SENSE  WHICH  AFTER ALL  WAS A RESONANCE IN AN ORDERED CRYSTAL LATTICE OF DISCRETE SCATTERERS !LTHOUGH AUTHORS OFTEN REFER TO hFREE "RAGG WAVES v SUCH OBJECTS ARE FOUND PRIMARILY AMONG THE  PARASITIC CAPILLARIES REFERRED TO IN 3ECTION   OR AMONG THE  RING WAVES PROPAGATING OUT FROM THE IMPACT OF A FALLING DROP 4HIS RAISES  A QUESTION ABOUT THE MEANING OF SUCH OFTEN 
 MTI AND PULSE DOPPLER RADAR 119  hITI radar using range gates atld filters is usually more complex than an MTI with a  s~ngle-delay-line canceler. The additional complexity is justified in those applications where  good MTI performance and the flexibility of the range gates and filter MTI are desired. The  better MTI performance results from tile better match between the clutter filter characteristic  and the clutter spectrum. 
 TABLE 18. 8 Scatterometers Name Spacecraft Country Year Antenna Band Polarization RadScat Skylab USA 1973, 1974 Pencil beam Ku VV , HH SASS Seasat USA 1978 Fanbeams Ku VV , HH ESCAT ERS-1 Europe 1992-6 Fanbeams C VV ESCAT ERS-2 Europe 1995- Fanbeams C VV NSCAT ADEOS I US/Japan 1996–1997 Fanbeams Ku VV , HH SeaWinds QuikSCAT US 1999– Conical scan Ku VV , HH SeaWinds ADEOS II US/Japan 2002– Conical scan Ku VV , HH CNSCAT SZ-4 China 2003 2 conical scan Ku VV , HH ASCAT MetOp-1 Europe 2006 Fanbeams C VV Scat Aquarius USA 2009 3-beam push L VV , VH, HV , HH ch18.indd   56 12/19/07   5:15:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Aperture blocking  degrades the performance of an antenna by lowering the gain, raising the sidelobes, and filling  in the nulls. The effect of aperture blocking can be approximated by subtracting the antenna  pattern produced by the obstacle from the antenna pattern of the undisturbed aperture. This  procedure is possible because of the linearity of the Fourier-transform that relates the aperture  illumination and the radiated pattern, An example9 of the effect of aperture blocking caused by  the feed in a paraboloid-reflector antenna is shown in Fig. 
 OSCILLATORS HAVE BEEN CAPABLE OF GREATER POWER THAN GYRO 
 16.3 repetition rate has “time jitter” (see Vol. 19,Chap. 25ofthe Radiation Laboratory Series). 
 S. L. Johnston (ed.), Radar Electronic Counter-Countermeasures , Norwood, MA: Artech House,  Inc., 1979. 
 1992   − K. Schmitt, D. Kähny, W. 
 Thesineorthecosinetermscantakeanyvaluebetween+1and-1,including zero.forachangeinrangecorresponding tooneRFwavelength. Forthisreason,theextrac­ tionofthehigher-order modulation frequencies isnotpractical withastationary target,such asinanaltimeter. Inordertousetheproperties oftheBesselfunction toobtainisolation inanFM-CW altimeter, whenthedoppler frequency isessentially zero,theroleofthedoppler frequency shift mayheartificially introduced bytranslating thereference frequency tosomedifferent value. 
 The  scanning niodulatiori and the error signal would be lost if the receiver were to saturate. In the  cor~icnl-scat] tri~ckirlg radar 2111 ACiC' tlint r~iailitains tlic d-c lcvcl colistatit rcsi~lts in at1 error  signal that is a true itidicatioti of tlie angular pointing error. The d-c level of the receiver must  bc rnairitaitied cotistant if tlie at~gular error is to be linearly related to the angle-error signal  voltage. 
 PULSE DOPPLER RADAR  4.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 smaller moving targets in the main beam. This is a particularly severe problem in  a medium-PRF radar, where all-aspect target performance is usually desired, since  these returns compete with targets of interest. In a high-PRF radar, there is little if any  range region clear of sidelobe clutter, such that the sidelobe clutter portion of the dop - pler spectrum is often not processed (since target detectability is severely degraded in  this region). 
 A factor Ls (greater than unity), called the system losses, has been  inserted to account for the many ways that loss can occur in a radar. This loss factor  can be quite large. If the system loss is ignored, it might result in a very large error in  the estimated range predicted by the radar equation. 
 These ring-angels are associated with birds flying away from roosting areas. Angels can also be  caused by second-time-around echoes or large signals that enter the radar via the antenna  sidelobes.  REFERENCES  1. 
   30!#% 
 POLARIZATION BACKSCATTER SIGNATURES OVER PADDY RICE FIELD AND THEIR RELATIONSHIP WITH BIOLOGICAL  VARIABLES v 2EMOTE 3ENSING OF %NVIR  VOL   PP n    3 6 .GHIEM ET AL  h0OLARIMETRIC SIGNATURES OF SEA ICE    EXPERIMENTAL OBSERVATIONS v   * 'EOPHYS 2ES  VOL   PP n    ! -ARTINI  , &ERRO 
 243–252, Algorithms for Synthetic Aperture Radar Imagery VI , E. G. Zelnio (ed.), 1999. 
 Oguchi, “Electromagnetic wave propagation and scattering in rain and other hydrometeors,”  Proc. IEEE , vol. 71, pp. 
 Moving the zeros gives a 4 or 5 dB increase in the MTI improvement factor for specific clutter spectral spreads, as compared with keeping all three zeros at the origin.19 It is interesting to note the width of the rejection notches for the different RESPONSE (dB) 14.4 HITS PERBEAMWIDTH Z-PLANE ZEROATORIGIN UNIT CIRCLEZERO ATORIGIN1POLE ON X AXIS AT DISTANCE K, FROM CENTER OF UNIT CIRCLESINGLE-DELAYCANCELERDELAYLINE . POLES SHOWN FOR K, =0.5, K2=O FIG. 15.22 Two-delay canceler. 
 REGISTER GENERATOR  4HE FEEDBACK CONNECTIONS THAT PROVIDE THE MAXIMAL 
 32, no. 16, pp. 66,  68 69. 
 Scanning is accomplished in  the parabolic torus by moving the feed.  There are other variations of parabolic reflectors such as cheeses, pillboxes, and hoghorns,  descriptions of which may be found in the literature.1•7  Feeds for paraboloids. 1•9• 130 The ideal feed for a paraboloid consists of a point source of  illumination with a pattern of proper shape to achieve the desired aperture distribution. 
 At3000 Me/see, forexample, 4500 kwhave been obtained from the HP1OV, and the British report 3700 kwpeak atanaverage power level of5kwfrom asimilar tube, the BM735. The general rule that maximum pulse power isproportional towave- length squared isillustrated bythefalling-off ofpower athigh frequencies. Exceptions tothis rule arethe magnetrons inthe 20-to30-cm range, whose pulse power output isnot ashigh asmight beexpected. 
 TION  BIRDS  INSECTS  AND DUCTING BETTER THAN CAN BE DESCRIBED IN WORDS !TTENTION IS ESPECIALLY DIRECTED  TO THE FINAL SECTION  IN THIS CHAPTER  h#ONSIDERATIONS  !PPLICABLE TO -4) 2ADAR 3YSTEMS v WHICH PROVIDES INSIGHT INTO BOTH HARDWARE AND ENVIRONMENTAL LESSONS LEARNED DURING MANY DECADES OF -4) SYSTEM DEVELOPMENT Ó°ÓÊ  /," 1 /" Ê/"Ê /Ê, , 4HE PURPOSE OF -4) RADAR IS TO REJECT RETURNS FROM FIXED OR SLOW 
 226-235, November, 1967.  85. Blass, J.: Multidirectional Antenna-A New Approach to Stacked Beams, 1960 I RE lt11ematio11u/  Co11re11rio11 Record, pt. 
 ., 7.Barton,D.K.,andH.R.Ward:"Handbook ofRadarMeasurement," Prentice-HalL Inc.,N.J.1969. 8.Manasse, R.:RangeandVelocity Accuracy fromRadarMeasurements, unpublished internalreport datedFebruary,' 1955,MITLincolnLaboratory, Lexington, Mass.(Notgenerally available.) 9.Slepian, D.:Estimation ofSignalParameters inthePresence ofNoise,IRETrans.,no.PGIT·3, pp. 68-89,March,1954.' 10.Siebert,W.McC.:ARadarDetection Philosophy, IRETrans.,vol.IT·2,pp.204-221, September, 1956. 
 Sector (or“B”) scan isa modification ofcircular scan inwhich the beam scans toand froonan arc. This motion iscommon incertain airborne radars forsurface search. The sector istypically 75°wide, and 1to-and-fro cycle may occupy 1sec. 
 TIME DISPLAY OF TACTICAL INFORMATION AND CURRENT FORCE POSITIONING 4HUS  A RADAR ASSESSMENT PROVIDED BY !2%03 MAY BE DISPLAYED AS A TACTICAL OVERLAY UPON THE OPERATING PICTURE &IGURE  IS AN ILLUSTRATION OF SUCH A #/0 DISPLAY )N THIS ILLUSTRATION  THE RADAR COVERAGE OF THREE COASTAL SURVEILLANCE RADARS IS SHOWN ALONG WITH THE TRADITIONAL HEIGHT VERSUS RANGE COVERAGE DISPLAY TYPICAL OF THE PERSONAL COMPUTER VERSION OF !2%03 !S THE .AVY PROGRESSED INTO WEB 
 As the frequency is changed, the phase across the aperture tilts linearly, and the beam is scanned. Frequency-scanning systems are relatively simple and inexpensive to implement. They have been developed and deployed in the past to provide elevation-angle scanning in combination with mechanical hor- izontal rotation for 3D radars. 
 This spectrum space has been reduced considerably  over the years with the advent of many commercial users of the spectrum in the age of  “wireless” and other services requiring the electromagnetic spectrum. Thus, the radar  engineer is increasingly experiencing smaller available spectrum space and bandwidth  allocations that can be vital for the success of many radar applications. Signal-to-Noise Ratio. 
 However, itintroduces problems ofitsown.Cross-polarization lobesareproduced bythe offsetgeometry, whichmayseriously deteriorate theradarsystemperformance. 1,17Also,itis usuallymoredifficult toproperly support and toscananoffset-feed antenna thanacircular paraboloid withrearfeed. flDratio.Animportant designparameter forreflector antennas istheratioofthefocallength Itotheantenna diameter D,orflDratio.Theselection oftheproperflD ratioisbasedonboth mechanical andelectrical considerations. 
 DOPPLER COORDINATES FOR TWO DIFFERENT 8 
 TABI.~ 14.1.—RECOMMEXDED POWER SOLTWES Radar load, watts IRecommended radar power source Less than 150....... 150-250 ............ 25&750 ... 
 SPHERE  SPECIFICALLY AURORAL % 
 H., and G. V. Trunk: Angular Accuracy of a Scanning Radar Employing a Two-Pole  Filter, IEEE Tram., vol. 
 ANE-1,  no. 2, pp. 8-14, June. 
 COMPRESSION NETWORK  THE SYSTEM INSTABILITY NOISE WILL BE EQUAL TO OR LESS THAN THERMAL NOISE FOR EITHER DISTRIBUTED CLUTTER OR POINT CLUTTER  AND THE PEAK CLUTTER SIGNALS WILL VARY FROM ABOUT  D" ABOVE THERMAL NOISE FOR EVENLY DISTRIBUTED CLUTTER TO  D" ABOVE THERMAL NOISE FOR STRONG POINT CLUTTER "ECAUSE THE -4) CANCELER IS EXPECTED TO ATTENUATE CLUTTER BY  D"  THE SECOND LIM 
 Averticalslitinanopaquescreen placedinthefocalplaneofthespherical lensdisplays allrangesinaparticular direction. The slitisoffsetfromtheoriginbecauseofthedcbiasthathadtobeaddedtothesignalatthe inputtotheCRTinordertorecordonfilm.Iftheslitwereplacedontheopticalaxis, thepresence ofthedcbiaswillcauseadegraded imagebecause theenergyfromthebias overlaps thedesiredimage.Thisisavoided byplacingtheinputsignalonaresidual carrier {'" Conical lensCylindrical lensSpherical lens Slit Si<}nol-hisloryfilm andweighting transparancy Figure14.6Optical processor forsynthetic aperture radar.. frequency, called the olfiut.freqlre~lcy, along with the dc bias. 
 ON 
 ITY WHEN IN ORBIT ABOUT A PLANETARY BODY ARE RIGIDLY GOVERNED BY ORBITAL DYNAMICS  SUMMARIZED COMPACTLY BY +EPLERS LAWS &URTHER  ACCESS BY AN 3"2 TO A GIVEN AREA OF INTEREST DEPENDS ON THE ROTATION RATE OF THE PLANET  AS WELL AS THE SATELLITES POSITION ALONG ITS ORBIT AND THE RADARS VIEWING GEOMETRY 4HUS  THE PRIMARY PARAMETERS TO BE INCLUDED IN 3"2 MISSION DESIGN INCLUDE ORBITAL ALTITUDE  SPACECRAFT ON 
 J. Hoft, Solid-State Transmit/Receive Module for the PAVE PAWS Phase Array Radar, Microwave /., Horizon House, Norwood, Mass., October 1978. NOTE: Frequency: 420-450 MHz; pulse width: 0.25-16 ms; duty cycle: 0-25 percent. 
 OF 
 R. W. Larsen, A. 
 THESES ADDED TO THE DESIGNATION INDICATES VARIABLE SYSTEMS THOSE WHOSE FUNCTIONS MAY BE VARIED THROUGH THE ADDITION OR DELETION OF SETS  GROUPS  UNITS  OR COMBINATIONS THEREOF  7HEN THE DESIGNATION IS FOLLOWED BY A DASH  THE LETTER  4  AND A NUMBER  THE  EQUIPMENT IS DESIGNED FOR TRAINING )N ADDITION TO THE 5NITED 3TATES  THESE DESIGNA 
 Some of these differences are mentioned in Section 11.1 of Chapter 11 “Solid- State Transmitters.” Briefly, proponents of solid state might say that they do not need  a hot cathode as does a vacuum tube, do not require high voltages or magnets, do not  produce X-ray radiations as some vacuum tubes do, have “graceful degradation,” and  that maintainability is its key asset. On the other hand, proponents of vacuum tubes  might say that radars using solid-state transmitters have limited peak power and thus  need to operate with a long pulse and a high duty cycle, which require the use of  pulse compression. The long pulse can mask or eclipse target echoes at short range so  that an additional short pulse transmission is needed to unmask the eclipsed echoes  at short ranges. 
 61. Pettengill, G. H.: Radar Astronomy, chap. 
 Air Force in Alaska (SEEK IGLOO Program), northern Canada (North Warning Program), and Berlin. The radar is also in use in Korea, for NATO in Iceland, and for Saudi Arabia as part of the Peace Shield Program. MTBF for these radars has been demonstrated to exceed the 1076-h specification, and more than 750,000 h MTBF has been demonstrated for the 100-W solid-state RF power amplifier modules. 
 Models of canonical shapes. ( a) Dihedral A. ( b) Dihedral B. 
 2.5. 4.2. Bandwidth, Power, and Information Rate.—If aradar system were used tofind only the direction ofatarget, range information being suppressed, itwould beoperating very much like atelevision camera. 
 Oceanic Eng ., vol. OE-10, pp. 368–375, 1985. 
 , 
 MOUNTED RADAR FOR CLOUD STUDIES  4HE #ANADIAN .ATIONAL 2ESEARCH #OUNCIL HAS DEVELOPED A  SIMILAR AIRBORNE RADAR SYSTEM 3PACEBORNE 2ADARS  !MONG THE MORE SIGNIFICANT CHALLENGES FACING RESEARCHERS  TODAY IS THE NEED TO MAKE GLOBAL MEASUREMENTS OF PRECIPITATION 5NDERSTANDING GLOBAL CLIMATE REQUIRES THAT QUANTITATIVE MEASUREMENTS OF PRECIPITATION BE MADE THROUGHOUT THE WORLD  PARTICULARLY IN THE TROPICS AND OVER THE OCEANS 3ATELLITE OBSERVATIONS APPEAR &)'52%     4AIL 
 3. Quigley, W. W.: Gemini Rendezvous Radar, Microwave J., pp. 
 These procedures are relatively time consumin g, since they are serially  operated.  A considerably faster procedure, which operates as a parallel process, is the M o- nopulse Procedure.  13.2 Monopulse Radar   The so -called Monopulse Procedure makes possible a considerable improvement. 
 RESENTS A TRADEOFF AMONG SEVERAL DESIGN ISSUES  AND THE RESULTANT CIRCUIT CONFIGURATIONS REPRESENT A COMPROMISE AMONG THE GOALS OF OPTIMUM 2& PERFORMANCE  HIGH LEVELS OF INTEGRATION  AND FABRICATION YIELDS THAT ARE CONSISTENT WITH PROCESSING CAPABILITIES OF 'A!S --)#S !MONG THE SINGLE 
 Datta-Barua, S.; Walter, T.; Blanch, J.; Enge, P . Bounding higher-order ionosphere errors for the dual-frequency GPS user. Radio Sci. 
 Fabrizio, A. B. Gershman, and M. 
 Marks IIIA and IIIB, ARI 5153, S.D.0296(1), ch 1 2nd edn, Air Ministry, Nov 1943 ( www.vmarsmanuals.co.uk ) [5] Lucero Inquisitor for ASV and H 2S, TRE Report No. 14/R.104/BVB, 1942 (TNA AVIA 26/1882) [6] Operational effectiveness of ‘Lucero ’for ASV/BA, CCDU Trial 43/32, June 1943 (TNA AIR 65/25). [7] Roberts A 1947 Radar Beacons MIT Radiation Laboratory Series vol 3 (New York: McGraw Hill)Airborne Maritime Surveillance Radar, Volume 1 6-5. 
 The output power is coupled from the stabilizing coaxial cavity. The cavity operates  in the TEoll mode with the electric field lines closed on themselves and concentric with the  circular cavity. The RF current at every point on the circumference of the cavity has the same  phase, so that the alternate slots which couple to the stabilizing cavity are of the same phase as ,*. 
 BASED PROCESSORS CAN BE A FACTOR OF TEN OR MORE  SMALLER AND LESS COSTLY THAN SYSTEMS BASED ON GENERAL 
 Although there has been much interest in the millimeter portion of the electromagnetic spectrum, there have been no operational radars above Ka band. High-power sensitive re- ceivers and low-loss transmission lines are difficult to obtain at millimeter wave- lengths, but such problems are not basic. The major reason for the limited utility of this frequency region is the high attenuation that occurs even in the "clear" atmosphere. 
 JAMMING TECHNIQUES FOR MULTI 
 The advantage ofstagger-tuned amplifiers lies inthe fact that simple single-tuned cir- cuits areused throughout, afact that makes forease ofmanufacture and servicing. There areother schemes forobtaining large bandwidths. Feedback pairsl and feedback chainsz have both been used fairly extensively. 
 2.3, some definitions contain an element of arbitrariness, and it is common for different authors to employ different definitions of some of the range-equation factors. Of course, when . generally accepted definitions do exist, they should be observed. 
 But just as high-frequency electromagnetic energy  can travel through the ‘pipeline’ of a wave-guide, so  oscillations can be created in a hollow space. If you  picture a chunk carved out of a block of metal, forming  a spherical space with only a very small opening, then  you can imagine inside this cavity currents circulating  on the inside of the opening, and associated electric and  magnetic fields inside the cavity.  This is a startling conception to the man accustomed  to the normal theory of oscillatory circuits with induc-  tances and capacities, but in centimetric radar we have  started along a new avenue of radio physics. 
 FED REFLECTOR SYSTEM  THE SIDELOBE LEVEL CAN BE REDUCED BY INCREASING THE FEED PATTERN EDGE TAPER            
 46 52. January, 1960.  14. 
 2.46  Tropospheric-Absorption Loss  ...........................  2.47  Lens-Effect Loss   ................................................  2.52  Other Tropospheric Losses  ................................ 
 Transmitters that employ the  magnetron power-oscillator are usually smaller in physical size than transmitters that employ  the power amplifier. The various amplifier transmitters, however, are generally capable of  higher power than the magnetron oscillator. Amplifiers are of greater inherent stability, which  is of importance for MTI and other doppler radars, and they can generate more conveniently  than can power oscillators the modulated waveforms needed for pulse-compression radar. 
 This can be done by inserting a lens between the radar and the tar - get61,62 or by reflecting the radar beam off a collimating reflector. This latter concept  is known as the compact range  because a beam of parallel rays can be generated in a  much shorter distance than would be possible without the collimating device. The reflector offers a different way to collimate a beam. 
 ArcSAR for detecting target elevation. Electron. Lett. 
 M. Ellis, R. Oye, A. 
 TROMAGNETIC PERFORMANCE $IELECTRIC AND MAGNETIC $ØLLENBACH LAYERS TYPICALLY RANGE FROM ABOUT  MM TO  CM  IN THICKNESS 4HE MAGNETIC VERSIONS ARE  AS HEAVY  LBFT    MAKING THEM IMPRACTICAL FOR MOST TACTICAL APPLICATIONS 4HE FRONT FACE AND THE METAL BACKING OF THE $ØLLENBACH LAYER ARE ITS ONLY SOURCES  OF REFLECTION 4HE USE OF PHYSICALLY REALIZABLE MATERIALS MAKES IT IMPOSSIBLE TO FORCE EITHER REFLECTION TO ZERO 4HE DESIGN OBJECTIVE  THEREFORE  IS TO CHOOSE THE ELECTRICAL PROPERTIES OF THE LAYER SO THAT THE FRONT 
 RENTS OVER SEVERAL WAVELENGTHS  ALONG THE SURFACE 4HEY ARE ABLE TO REGISTER QUITE  RESPECTABLE PERFORMANCES  THEREFORE  SIMPLY BECAUSE A THIN LAYER ATTACHED TO A METALLIC SURFACE NEED NOT BE VERY HEAVY )N THIS RESPECT  THE SURFACE TRAVELING 
 Long, “Calibrating SeaWinds and QuikSCAT scatterometers using natural  land targets,” IEEE Geoscience and Remote Sensing Letters , vol. 2, pp. 182–186, 2005. 
 Digital Ionogram DataBase. Available online: http://ulcar.uml.edu/DIDBase/ (accessed on 5 February 2018). 27. 
 CONTROLLED TUBES WERE SUCCESSFULLY EMPLOYED IN SUCH IMPORTANT RADAR APPLICATIONS AS (& OVER 
 At the end of this chapt er, students should understand the fundamentals of radar and recognize the  key performance parameters associated with primary radar specifications.   The student should be able to:    explain the basic operation of a pulse radar system;    define range, bearing, and altitude as they relate to a radar system;    discuss how pulse width, peak power, and beam width affect radar performance;    describe the factors that contribute to or deteriorate from radar resolution;    know the advantages of a frequency diversity radar ;    using a block diagram, describe the basic function, principles of operation, and  interrelationships of the basic units of a radar system.      Preamble   The basic principle of operation of primary radar is simple to understand. 
 Drane, C. J.: Dolph-Chebyshev Excitation Coefficient Approximation. l EEE Trans., vol. 
   %.6)3!4S !3!2  0!,3!2  #/3-/  4ERRA3!2 
 3.13] SEA R.ETCR.V A.YD GRO~.YD RE1’CR.\” 93 confusion between seaand land. Sea return isstrongest inthedirection from which the wind isblowing, This effect isshown clearly inFig. 3.22, which notonly shows substantial seareturn intheupwind and down- wind directions (north and south), with novisible return indirections crosswind from the radar, but also shows amuch weaker seareturn in theprotected inner harbor than inthe outer harbor. 
 AES-3. pp. 366-373, NOV. 
 The ﬁrst sidelobes were preserved partly because they were in the integrating region, as shown in Figure 5a, but were less than−30 dB. This was much lower than that for the rectangular window (Figure 5c), and was achieved without the loss of resolution su ﬀered when using the Taylor window (Figure 5d). To further illustrate the performance of the proposed method, azimuth resolution, peak sidelobe ratio (PSLR), and integrated sidelobe ratio (ISLR) [ 17] were given as follows. 
 TO 
 The four black rectangles are the four major areas of subsidence. A-E are ﬁve points of subsidence, detailed in Figure 6. 4.2. 
 First, predict a new target state estimate X t tk k∧ +( | )1 of the state X(tk+1) at time tk+1  given all measurements up to time tk  X t t t X t A tk k k k p k∧ + = + ( | ) ( ) ( ) ( )1 φ (7.29) along with its covariance  P(k + 1 | k) = f�(tk)P(k | k)f�(tk)T + Q(tk) (7.30) Then, update the target state using the ( k + 1)st radar measurement  X t t X t t K Y H t Xk k k k k k k∧ + +∧ + + +∧ = + − ( | ) ( | ) [ ( )1 1 1 1 1( ( | )] t tk k+1  (7.31) and its covariance  P(k + 1 | k + 1) = [I − Kk+1H(tk+1)]P(k + 1 | k) (7.32) ch07.indd   29 12/17/07   2:14:12 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 J 7. Lind, G.: A Simple Approximate Formula for Glint Improvement with Frequency Agility, IEEE Trans.,  vol. AES-8, pp. 
 It is also possible to use a dual sidelooking antenna pattern and  detect the phase difference between the two mutually conerent observations of a target  separated in time. The phase-detection AMTI method allows slowly moving targets to be  detected when the aircraft velocity is large.  Ground relief, such as due to hills or mountains, stands out on SAR imagery because o  the shadows they form, especially when viewed at low grazing angles. 
 NAL INTERFERENCE WITH MINIMAL AND PREDICTABLE  EFFECT ON SYSTEM NOISE TEMPERATURE -OST RADARS EMPLOY AMPLIFIERS PRIOR TO 34#  SO THEY CANNOT ATTENUATE EXTERNAL INTERFERENCE WITH 
 Increasing the  antenna gain at high angles hut not at low angles will therefore improve the target echo with  respect to the cluttcr.9R  r cq (.4~r so ,a£l1 ~ ta~, 1 c••  •··· "(j .. ....  IOI  Hgurt> 7.27 Antenna elevation pattern ror a long-range air-search radar to achieve high-angle coverage  when STC is employed. 
 Oceanic Technol. , vol. 5, pp. 
 RIGHT CORNER OF THE DISPLAY REPRESENTS THE AREA WHERE A GROUND 
 MINUTE DELAY BETWEEN THE RADAR AND LIDAR CLOUD PROFILING MEASUREMENTS 4HE #02 WAS DEVEL 
 PULSE AND THUS WILL CANCEL LIKE STATIONARY CLUTTER 2ULE  $ESIGN THE SYSTEM TO BE FULLY COHERENT !LL FREQUENCIES AND TIMING SIGNALS  SHOULD BE GENERATED FROM A SINGLE MASTER OSCILLATOR $OING THIS MAKES THE ENTIRE SYS 
 -1'tiis theti is one nietliod for combining frequency scan with pulse compression, where the  angular resolution depends on the antenna beamwidth and the range resolution depends on  the group time delay r,.  Ttie frequency-scan technique is well suited to scanning a beam or a number of beams in a  single angle coordinate. It is possible to use the frequency domain to produce a TV (raster)  type of scan in two orthogonal atigular coordinates by employing an array of slightly disper-  sive arrays fed frorn a single highly dispersive array. 
 17.3.1 The resulting pulse, taken from point Yofthat diagram, blocks the grid ofvsb and initiates the action ofthe delay circuit comprising the sawtooth generator Vbb, the cathode follower Vti, and theblocking oscillator VT.. The tube V,aisdelayed infiring byits excessive bias. When VTCfires, itscathode drives the l-psec delay line, and the delayed pulse returns through VTb toturn offthe blocking oscillator. 
 The basic disadvantages of all nonparametric detectors are that (1) they have  relatively large CFAR losses; (2) they have problems with correlated samples; and   (3) one loses amplitude information, which can be a very important discriminant  between target and clutter.32 For example, a large return ( cross section ≥ 1000 m2) in  a clutter area is probably just clutter breakthrough. See “Radar Detection Acceptance”  in Section 7.3. Clutter Mapping. 
 SCAN CONSISTS OF A PLAN VIEW  X  Y PLANE  OVER A DEFINED RANGE OF DEPTH  Z  .OTE THAT THESE TERMS ARE NOT THE SAME AS USED IN  CONVENTIONAL RADAR DISPLAY 4HE RECEIVED TIME WAVEFORM CAN BE DESCRIBED AS THE CONVOLUTION OF A NUMBER OF  TIME FUNCTIONS EACH REPRESENTING THE IMPULSE RESPONSE OF SOME COMPONENT OF THE RADAR SYSTEM IN ADDITION TO NOISE CONTRIBUTIONS FROM VARIOUS SOURCES .OTE THAT TWO ANTENNAS ARE USED ONE TRANSMITS AND ONE RECEIVES   ST ST ST ST S T S T S T RS C T               AF GF GR ST N TAR       WHERE  SST     SIGNAL APPLIED TO THE ANTENNA  SADT     ANTENNA IMPULSE RESPONSE  SCT     ANTENNA CROSS COUPLING RESPONSE&)'52%   0REDICTED AND ACTUAL PULSE RESPONSES OF LOADED 4%- HORN ANTENNA #OURTESY )%%                 "     ! #" $   " " $"#! #" %  "  "   "    "   
 The false-alarm probabilities of practical radars are quite small. The reason for this is that  the false-alarm probability is the probability that a noise pulse will cross the threshold during  an interval of time approximately equal to the reciprocal of the bandwidth. For a 1-MHz  bandwidth, there are of the order of 1Q6 noise pulses per second. 
 ( S. S. Robertson3 © AT&T 1947. 
 CHANNEL TAPER  HAVING SMOOTHLY TAPERED  % 
 This technique can be extended to more than two pulses by using the necessary phase-center displacements for each pulse. In order to maintain the ef- fective PRF, the displacement must compensate for the two-way transmission path. To accomplish this displacement, near-field antenna principles are utilized. 
 PASS OBSERVATIONS ARE SEPARATED IN THE VERTICAL  PLANE  THEN INTERFEROM 
 lEEE,  vol. 60, pp. 743-744, June, 1972. 
 15.266 Six-pulse filter for targets at/T = 0.3 that rejects fixed clut- ter. FIR RESPONSEFIR RESPONSE MISMATCH LOSS MISMATCH LOSS . RELATIVE DOPPLER fd/PRF FIG. 
 336-342, July-August 1984. 133. Kirk, Jr., J. 
 §S 0., PULSE AUTOCORRELATION FUNCTION FOR 4"     A      AND FD    . 
 RANGE PORTION  OF THE PROFILE AT THE TOP OF THE ELEVATION SCAN )T USES THE LARGEST PULSE COMPRESSION RATIO n  %ACH BEAM POSITION OVERLAPS BY AS MUCH AS  AND MULTIPLE FREQUENCY  &)'52%  4ERRAIN HEIGHT ESTIMATION #OURTESY 3CI4ECH 0UBLISHING  . 
 If this charge were  allowed to remain, the peak voltage on the network would increase with each cycle and build  up to a high value with the possibility of exceeding the permissible operating voltage of the  thyratron. The mismatch of the pulse-forming network to the nonlinear impedance of the tube  might also cause a spike to appear at the leading edge of the pulse. The despiking circuit helps  minimize this effect. 
 TRUM FOR A SIDE 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 7 .12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 estimate of s. However, since T is set by an estimate ˆσ, it has some error and must be  slightly larger than the threshold that one would use if s were known exactly a priori. 
 878–880, November 1974. 12. D. 
   $$# $OC !$   -ARCH    2EPRINTED IN 2EFERENCE     4 3 'EORGE  h&LUCTUATIONS OF GROUND CLUTTER RETURN IN AIRBORNE RADAR EQUIPMENT v  0ROC )%%  ,ONDON   VOL   PT )6  PP n  !PRIL    & 2 $ICKEY  *R  h4HEORETICAL PERFORMANCE OF AIRBORNE MOVING TARGET INDICATORS v  )2% 4RANS    VOL 0'!% 
 ROR 
 Sensors 2019 ,19, 1649 orthogonal components, the energy of the whole image can be computed as the sum of the squares of the singular values. In the matrix a large part of the energy remains conﬁned in the ﬁrst left and ﬁrst right singular vectors of matrices Uand V. An example of the ﬁrst right and ﬁrst left singular vectors of the SVD decomposition are shown in Figure 3. 
 For example, radar systems are no longer limited to the  LFM waveform; instead, radar system capabilities can be extended to take advantage  of the more complex processing associated with the nonlinear FM waveform. AN/TPS-59 and AN/FPS-117 Surveillance Radars.55 The AN/TPS-59 and AN/ FPS-117 are a family of L band, long-range surveillance radars that employ LFM  waveforms. The antenna is mechanically rotated in azimuth, and electronic pencil- beam scanning is performed in elevation. 
 Because of the highly nonlinear effect de- scribed in the preceding subsection, each Class-C stage tends to speed up the rise and fall times of the driving pulse. Consequently, an input pulse shape with slow rise and fall times may be necessary to achieve the desired output-pulse spectral composition. Control of the rise and fall times is complicated by the necessary use of ex- ternal bias injection networks. 
 SHIFTED SIG 
 211-215, October 1980. 98. Radar Cross-Section Measurements, General Motors Corporation, Delco Electron. 
 Such correction is,z M FIG.9.36.—Deck-tilt error. ThearcHB, which isthebearing ofthebeam, isgreater than thearcHA, which isthebearing asin- dicated ifdeck-tilt error isnotcompensated MBA represents ameridian on asphere. however, inapplicable ifthe radiation isavertically fanned beam ora pencil beam which must oscillate rapidly inavertical plane. 
 ERROR 
 http://www.skyrocket.de/space/index_frame.htm?http://www.skyrocket.de/space/sat_mil_usa.htm  2. http://www.astronautix.com/craft/seasat.htm  3. http://directory.eoportal.org/pres_SIRShuttleImagingRadarMissions.html  4. 
 NOISE SAMPLES ARE INTEGRATED 4HE NUMBER OF SIGNAL SAM 
 NAvy, pioneer radar in,  19-20  WATSON-WATT, SIR ROBERT,  21, 22-25; 53  Wave-guide, 114, 122  Wilkins, A. F., 24, 25  Willemite, 61  Williams, F. C., 29  Willshaw, W. 
 DOMAIN CHARACTERISTICS OF THE RECEIVED PULSE COULD BE USED AS AN INDICATION OF DISTANCE 4HE INTERACTION BETWEEN THE ANTENNA AND THE LOSSY DIELECTRIC HALF SPACE IS ALSO SIG 
 For example, Sullivan et al.34 includes HH and HV X-band SAR images taken of the  same scene at the same time using HH and HV modes interleaved on a pulse-to-pulse  basis. The SAR described could, using pulse-to-pulse interleaving, transmit/receive first  HH, then HV , then VH, and then VV data, and produce four corresponding simultane - ously collected complex images, such that the phases of the corresponding pixels in the  four images bear a specific relationship to each other, depending on the target type. Novak et al.36 developed an optimal polarimetric whitening filter  for enhanced tar - get detection in such sets of fully-polarimetric SAR images. 
 MITTED PULSE  A TOTAL PHASE RUN 
 One operational advantage of Oboe in normal circum-  stances is that the task of getting an accurate fix is done  in the relative calm of the ground stations, and the calcu-  lation does not have to be carried out at the airborne or  ship-borne end.  Gee cannot be overloaded by a large number of  receivers being tuned at the same time to the ground  stations. Oboe, however, is directed to one group of  mobile transmitter-receivers. 
 Though the Burgers-Rott vortex model can generate a three-dimensional current ﬁeld, M4S can only recognize the plane components, thus causing the inadequate modulation of NRCS around the eddy cores. Some ﬁne structures of the eddies cannot be simulated, although the agreement between the observed and simulated brightness variations of the eddy spirals is generally good. The radar imaging model used for this study is still based on a number of simplifying assumptions. 
  D"  OR   -33,   r 
 FEED -ONOPULSE %LECTRONIC 3CAN !RRAYS  /PTICAL 
 The performance of these and other similar  four-port devices is described in Chapter 4 of Sherman.1 The subtractor outputs are called difference signals,  which are zero when the target  is on axis, increasing in amplitude with increasing displacement of the target from the  antenna axis. The difference signals also change 180 ° in phase from one side of center  to the other. The sum of all four-horn outputs provides a reference signal to control  angle-tracking sensitivity (volts per degree of error) to remain constant, even though  the target echo signal may vary over a large dynamic range. 
 252X.1977.IFF(London) Conf.Puh!.no.155. 19.Kirk.J.C,Jr.:ADiscussion ofDigitalProcessing inSynthetic Aperture Radar.IEEE TUlliS.. vol.AFS-II. 
 RATE BY TD   2C S  AND FD   nK 6R (Z   WHERE  2 IS THE TARGET RANGE M    6R   D2DT 3IGNAL 3PECTRUM #OMMENTS   XT  8  F    &OURIER TRANSFORM PAIR   !XT    "UT  !8  F      "5  F   ,INEARITY   X 
 As the specular regions are approached, on the other hand, the phase variation slows down and then reverses as the specular point is crossed. This results in a nonzero specular contribution to the integral. The phase varia-HALF-POWER POINTS10log(a/w2) . 
 In principle, the CW radar would seem to be the ideal method of obtaining doppler-  navigation information. However, in practice, leakage between transmitter and receiver can  limit the sehsitivity of the CW doppler-navigation radar, just as it does in any CW radar. One  method of eliminating the ill eflects of leakage is by pulsing the transmitter on and turning the  receiver ofT for the duration of the transmitted pulse in a manner similar to the pulse-doppler  radar described in Sec. 
 Hol'shakov: "Questions of the Statistical Theory of Radar, vol. 11." chaps 10 arid  11. Sovctskoyc Radio. 
 TO 
 STATE GAIN CALCULATIONS DESCRIBED IN &ITZGERALD  ANDGSTRACK J4 M  3ELECT THIS MODEL WHEN TARGET IS KNOWN EXPECTED TO BE ACCELERATING:ERO LAGS TO CONSTANT ACCELERATION HOWEVER  NOISE ERRORS ARE MUCH GREATER  -ODEL NO  #ONSTANT  DETERMINISTIC ACCELERATION A G  &ILTER OBJECTIVE IS TO MINIMIZE LAG PLUS C STANDARD DEVIATIONS  1 SUBMATRIX NOT APPLICABLE )NSTEAD  ASSUME CONSTANT PARABOLIC MOTION   ATBA A 
 FIRST CENTURY v 0ROC )%%%  VOL   PP n  -AY   2 3 3YMONS  h4HE CONSTANT EFFICIENCY AMPLIFIER v  .!" "ROADCAST %NGR #ONF 0ROC      PP n  2 3 3YMONS ET AL  h4HE CONSTANT EFFICIENCY AMPLIFIER! PROGRESS REPORT v PRESENTED AT .!"  "ROADCAST %NGR #ONF 0ROC    , 3IVAN  h4HE MODULATOR v #HAP  IN  -ICROWAVE 4UBE 4RANSMITTERS   ,ONDON #HAPMAN     (ALL    4 ! 7EIL  h4RANSMITTERS v #HAP  IN  2ADAR (ANDBOOK  ND %D  .EW 9ORK -C'RAW 
 The raised portion of the  Dipole\  (a) Parasitic  reflector  ~  (b) (cl  Figure 7.9 Examples or the placement of the feeds in parabolic reflectors. (a) Rear feed using half-wave  dipole; (b) rear feed using horn; (c) front-feed using horn. RADAR ANTENNAS 239  reflector is called an apex-marcl1ing plate. 
 1975.  129. Schwartzman. 
 RATE $ SURVEILLANCE AND MULTITARGET PRECISION TRACKING  $UAL 
 Boerner et al. (eds.) : Direct and Inverse Methods in Radar Polarime- try, Part 1, pp. 793- 807, Kluwer Academic Publishers, Jan. 
 Radar Conf .,  Alexandria (V A), USA, May 9–12, 2005, pp. 61–66. 114. 
 The echo from a moving target produces a frequency shift due to the doppler effect, which  is a measure of the relative r~elocity. Relative velocity also can be determined ftom the rate of  change of range. Tracking radars often measure relative velocity in this manner rather tliari trse  the doppler shift. 
 The digital command  to the second integrator is the output of the first integrator plus the desired carrier  frequency. This carrier may be defined by the initial value of the first integrator. The  desired initial phase of the waveform is the initial value of the second integrator or else  may be added to the second-integrator output. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 24.40  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 Another class of ECCM techniques is aimed to contrast the deceptive ECM. 
 566–570. 1953.  99. 
 The loss of gain varies in this  case from about 3.8 dB to 5.4 dB over the region of coverage. The dome need not be a  hemisphere but can be shaped to favor particular regions of space. The dome can consist of  dielectric-loaded circular waveguides inserted into holes drilled in the hemispherical shell. 
 The noise entering the IF filter (the terms filter and amplifier are used interchangeably) is  assumed to be gaussian, with probability-density function given by  where p(v) do is the probability of finding the noise voltage v between the values of 11 and  v + dl,, $o is the variance, or mean-square value of the noise voltage, and the mean value of 11 is  taken to be zero. If gaussian noise were passed through a narrowband IF filter-one whose  bandwidth is small compared with the midfrequency-the probability density of the envelope  of the noise voltage output is shown by Riceg to be  where R is the amplitude of the envelope of the filter output. Equation (2.21) is a form of the  Rayleigh probability-density function. 
 S09, Sept. 28,1945. Microwave Ma@etrom, Vol. 
 Ulaby, R. K. Moore, and A. 
 It may originate within the receiver itself,  or it may enter via the receiving antenna along with the desired signal. If the radar were to  operate in a perfectly noise-free environment so that no external sources of noise accompanied  the desired signal, and if the receiver itself were so perfect that it did not generate any excess  noise, there would still exist an unavoidable component of noise generated by the thermal  motion of the conduction'electrons in the ohmic portions of the receiver input stages. This is  called thermal noise, or Johnson noise, and is directly proportional to the temperature of the  ohmic portions of the circuit and the receiver band~idth.~' The available thermal-noise power  generated by a receiver' of bandwidth B, (in hertz) at a temperature T (degrees Kelvin) is  equal to  Available thermal-noise power = kTB, (2.2)  where k = Boltzmann's constant = 1.38 x J/deg. 
 TRUM AND  SUPERIMPOSED  REPRESENTATIVE ESTIMATES OF THE MAGNITUDES OF THE ECHOES THAT MIGHT BE RECEIVED FROM A  NUMBER OF DIFFERENT  SHIP TYPES FOR THE SAME RADAR DESIGN AND  WAVEFORM PARAMETERS !LSO SHOWN  AT LEFT  ARE THE SPEED BANDS WITHIN WHICH THE SHIP ECHOES WOULD BE OBSCURED BY THE CLUTTER 4HE ABILITY TO PREDICT THESE OBSCURED BANDS BY MEANS OF %Q  CAN BE EXPLOITED FOR (& RADAR DESIGN AND SITING AND FOR SCHEDULING SHIP DETECTION OPERATIONS 4HUS COMBINING %Q  WITH AN OCEAN WAVE CLIMATOLOGY FOR ANY REGION ENABLES THE STATISTICAL PREDICTION OF RADAR SHIP DETECTION PERFORMANCE   &)'52%   #OMPUTED DOPPLER SPECTRA OF SEA CLUTTER FOR VARIOUS POLARIZATIONS THE RADAR FREQUENCY  HERE IS  -(Z WHILE THE DIRECTIONAL WAVE SPECTRUM ADOPTED IS A 0IERSON 
 9“01’.N. 79”35’TV. ever, the Fifteenth Air Force ofthe U.S. 
 CESSING INTERVALS #0)S  OF  . PULSES  ALL AT THE SAME 02& AND 2& FREQUENCY 4HE 02&  AND POSSIBLY THE 2& ARE CHANGED FROM ONE #0) TO THE NEXT 7ITH THIS CONSTRAINT  ONLY FINITE 
 SEARCH RADAR AND SMALL MISSILE TARGET PROPAGATION FACTOR.   4(% 02/0!'!4)/. &!#4/2  &0  ). 4(% 2!$!2 %15!4)/.   ÓÈ°ÓÇ 7HILE A GRAPHIC MAY BE USEFUL FOR VISUAL INSPECTIONS  IT MAY NOT BE USEFUL FOR AN  ENGINEERING ANALYSIS TASK !2%03 HAS MANY OTHER DATA DISPLAY FEATURES &OR EXAMPLE   THE PROPAGATION FACTOR VALUES AS SHOWN IN &IGURE  MAY ALSO BE EXPORTED IN A NUMBER OF DIFFERENT TEXT FORMATS FOR USE IN OTHER ENGINEERING APPLICATIONS , 
 The resistance can vary from thousands of ohms at zero bias to a fraction of  +  forward slole  Forward -bias  resislance  Package  inductance +  Reverse state  MJunclion  capacitance  ~ig~~ff~nce  Bock-bios  resistance . Figure 8.9 PIN diodes and simplified equivalent  circuits for forward and reverse states. TIIE RFCTRONICALI.Y STFfRl:D PIIASED ARRAY ANTENNA IN RADAR 291  an ohm with tens of milliamperes bias current. 
       a N a .  4ABLE  SUMMARIZES THE PHASE AND AUTOCORRELATION CHARACTERISTICS OF THE &RANK  CODE AND THE ,EWIS AND +RETSCHMER 0 THROUGH 0 POLYPHASE CODES&)'52%     !MBIGUITY FUNCTION OF A &RANK CODE OF LENGTH  -        . n°ÓÓ  2!$!2 (!.$"//+  0N K  0OLYPHASE #ODES  7HEREAS THE PREVIOUSLY DISCUSSED POLYPHASE CODES ARE  DERIVED FROM ,&- WAVEFORMS   0N  K  CODES ARE DERIVED FROM STEP APPROXIMATIONS OF  THE PHASE CHARACTERISTIC OF THE WEIGHTING FUNCTION OF .,&- WAVEFORMS 4HE WEIGHT 
 SPEED !$ CONVERTERS IN ORDER TO  REDUCE THE IMPACT OF DIGITAL OUTPUT TRANSITIONS ON THE PERFORMANCE OF THE !$ CON 
 SCAN RADARS IS THAT THE !'# BANDWIDTH MUST BE SUFFICIENTLY LOWER THAN THE SCAN FREQUENCY TO PREVENT THE !'# FROM REMOVING THE MODULATION CONTAINING THE ANGLE ERROR INFORMATION 0HASE 
 BORNE RADARS ARE USED FOR ALTIMETERS OR MAPPING  OTHER AIRCRAFT ARE UNDESIRED TARGETS  AND THE GROUND IS THE DESIRED TARGET )N THE CASE OF WEATHER RADARS  GROUND  BUILDINGS  AND AIRCRAFT ARE CLUTTER  AND RAIN OR SNOW IS THE DESIRED TARGET -ORE COMMONLY  RADARS ARE INTENDED FOR DETECTION OF AIRCRAFT  MISSILES  SHIPS  SURFACE VEHICLES  OR PERSONNEL  AND THE REFLECTION FROM WEATHER  SEA  OR GROUND IS CLASSIFIED AS CLUTTER INTERFERENCE !LTHOUGH THE BOUNDARIES OF THE RADAR RECEIVER ARE SOMEWHAT ARBITRARY  THIS CHAPTER  WILL CONSIDER THOSE ELEMENTS IDENTIFIED IN &IGURE  AS THE RE CEIVER 4HE RADAR EXCITER  GENERATES THE TRANSMIT WAVEFORMS AS WELL AS LOCAL OSCILLATOR ,/   CLOCK  AND TIMING SIGNALS 3INCE THIS FUNCTION IS USUALLY TIGHTLY COUPLED TO A RADAR RECEIVER  IT IS ALSO SHOWN IN &IGURE  AND WILL BE DISCUSSED IN THIS CHAPTER 4HE PURPOSE OF &IGURE  IS TO ILLUSTRATE THE FUNCTIONS TYPICAL OF A MODERN RADAR RECEIVER AND EXCITER 6IRTUALLY ALL RADAR RECEIVERS OPERATE ON THE SUPERHETERODYNE PRINCIPLE SHOWN  IN &IGURE  4HROUGH THIS ARCHITECTURE  THE RECEIVER FILTERS THE SIGNAL TO SEPARATE DESIRED TARGET SIGNALS FROM UNWANTED INTERFERENCE !FTER MODEST 2& AMPLIFICA 
 Asactually constructed, MTI syst~ms use 1-or2-~sec pulses and soarecapable ofhandling targets athousand feet orsoapart inrange. Ontheother hand, thesystem described inthis section works ononly one target, and although amoderate number ofadditional filters might beconsidered aspossible whenever anyone wishes todeal with multiple targets there iscertainly apractical limit totheir number. Possibly dividing the total range into 10pieces would bereasonable. 
 ING FROM SMALL ANTENNA POSITIONING ERRORS  GROUND SCREEN INHOMOGENEITIES  DIFFERENCES BETWEEN PREAMPLIFIERS  MUTUAL COUPLING  CABLE MISMATCH  THERMAL AND OTHER VARIATIONS OF CABLE CHARACTERISTICS  AND ALL THE ANALOG STAGES OF THE RECEIVER RESULT IN DISTORTION OF THE BEAM SHAPE AND HENCE DEGRADED RADAR RESOLUTION   ELEVATED SIDELOBES AND HENCE VULNERABILITY TO CLUTTER AND INTERFERENCE   POINTING ERRORS AND HENCE INCREASED TRACKING ERRORS   AND INTERFERER WAVEFRONT GEOMETRY PERTURBATIONS AND HENCE WASTED DEGREES OF FREEDOM IN ADAPTIVE BEAMFORMING  4O MITIGATE THESE EFFECTS  (& RADARS MUST EMPLOY SOPHISTICATED CALIBRATION SCHEMES  3EVERAL APPROACHES HAVE BEEN TRIED u 5SE OF AN EXTERNAL RADIATING ELEMENT IN THE NEAR 
 W. Hannan, “Optimum feeds for all three modes of a monopulse antenna, I: Theory; II:  Practice,” IEEE Trans ., vol. AP-9, pp. 
 Consider the hysteresis loop, or B-H curve, of Fig. 8.11. This is a plot of the magnetization  (gauss) as a function of the applied magnetic field (oersted) for a toroid-shaped section of  ferrirnagnetic material. 
 QUENTLY THE SURFACE 
 DOM (OWEVER  ELEMENT 
 1.:-CQUUJlent or~_tl!c_Angul,u Resolution oUla.d.ar, Proc. IEEE, vol. 63. 
 II are integers corresponding to ttie ntth row  and rrth colutnn, ~, is the phase difference needed between adjacent rows to steer the beam in  elevation. and (I, is the phase dilference between adjacent columns needed to steer in azimuth.  This is so~iletirrles called row/colunin steering. 
 TOR ANTENNAS &URTHERMORE  REFLECTOR ANTENNA DESIGNS ARE USED IN MODERN RADAR DESIGNS WHERE MODERATE SCAN RATES AND SCAN VOLUMES ARE REQUIRED OR LOW COST IS ESSENTIAL -ANY LEGACY RADARS EMPLOY REFLECTOR ANTENNAS WITH SINGLE FEED ELEMENTS OR A CLUSTER  OF FEEDS IE  AN ARRAY  WITH A FIXED BEAM 2& COMBINER OR DIVIDER NETWORK &IGURE  SHOWS SOME TYPICAL SINGLE 
 AP-16, pp. 217-223, March, 1968.  20. 
 H. Dyer. and N. 
 235–281. 11. V . 
 However, echoes from multiple-time-around targets will be spread  over a finite range as shown in Fig. 2.26c. The prf may be changed continuously within  prescribed limits. 
 ‘coil–coil “fi~”” mm Voltage adjusti-m .hmfict @.Ing ,!O.-”=tat Rect RectA- F I 111 II Exciter 1A+ n tr? FIc+.1415.-Schematic diagram ofaGeneral Electric voltage regulator Type GEA.2-B2 and 3-phase 230-volt alternator with exciter. Infield service, the usefulness ofthe finger-type regulators was limited bythetendency ofthe contacts tostick and burn, and bycorro- sion ofthecontacts due tomoisture and salt air. Inaddition, thedevice isvery difficult torepair inthe field. 
 It is always a matter of opinion what the major advances in radar have been. Others  might have a different list. Not every major radar accomplishment has been included  in this listing. 
 Direct RF sampling is considered the ulti - mate goal of digital receivers, with all the tuning and filtering performed through  digital signal processing. The advantage being the almost complete elimination of  analog hardware. However, not only does the A/D converter have to sample the  RF directly, but unless it is preceded by tunable RF preselector filters, the A/D  converter input must have the dynamic range to handle all of the signals pres - ent in the radar band simultaneously. 
 The eticrgy backscattercd fro111 tile sea will depend on tlie direction of the wind relative  to the directiori of the radar anteritia beam. It is generally higher when the radar beam looks  into the wind than when lookitig dowtiward or crosswind. There might be from 5 to 10 dB  variatioti it1 n" as the atitetlna scatis 360" it1 azitnutli. 
 However, iftheentireangularregionissweptwithin asinglepuIsebyafrequency-scan antenna, theresponse fromapointtargetwillbefrequency­ modulated duetothefinitebeamwidth. Adispersive timedelayfiltercancausethereceived echotobecompressed soastoachieve betterrangeresolution. Theamount ofrange­ resolution possible islimitedbythefinitetime-delay ofthesignalpropagating through the frequency-scan feednetwork. 
 POINTING ANGLES OF ADJACENT BEAMS AND  ! AND ! ARE THE  CORRESPONDING AMPLITUDES "INARY )NTEGRATOR  4HE BINARY INTEGRATOR IS ALSO KNOWN AS THE DUAL 
 However, the practicing engineer who is  involved in producing a  new type  of electrical engineering system often has  to depend on acquiring knowledge that was not usually covered in his or her engineering courses. The radar engineer, for example,has  to understand the major components and subsystems that make up a radar, as well as how they fit together. The Radar Handbook  attempts to help in this task. 
 È°Ó  2!$!2 (!.$"//+  BANDWIDTH AT THE )& FREQUENCY 4HESE ADVANTAGES HAVE PROVEN TO BE SO SIGNIFICANT  THAT COMPETITIVE FORMS OF RECEIVERS HAVE VIRTUALLY DISAPPEARED )N CONVENTIONAL ANTENNA SYSTEMS  THE RECEIVER INPUT SIGNAL IS DERIVED FROM THE  DUPLEXER  WHICH PERMITS A SINGLE ANTENNA TO BE SHARED BETWEEN TRANSMITTER AND RECEIVER )N ACTIVE ARRAY SYSTEMS  THE RECEIVER INPUT IS DERIVED FROM THE RECEIVE BEAM 
 Considerable power may  be coupled to the receiver since typically no more than 20 to 25 dB of isolation may  be expected from ferrite circulators. Antennas may form various beams. The transmit beam can be formed with uniform  aperture illumination to maximize the amount of energy on target, whereas the receive  sum ( Σ) beam is typically formed with a low-sidelobe taper to minimize the returns  from ground clutter. 
 C. Hansen, “Aperture theory,” in Microwave Scanning Antennas , vol. I, New York: Academic  Press, pp. 
 IRE, vol. 50, pp. 1515-1520, June, 1962. 
 [ 1.4.6 This is equivalent to passing a perfectly rectangular pulse through a filter of width  B. The time waveform of the output will be a pulse of width approximately r, but the slopes of  the leading and trailing edges are finite. An example of the shape of a bandwidth-limited  rectangular pulse is shown in Fig. 
 Ablockdiagram ofaCWtracking illuminator isshowninFig.3.9.31Notethatfollowing thewide-band doppler amplifier isaspeedgate. whichisanarrow-band tracking filterthatacquires thetarget'sdoppler andtracksitschang ingdoppler frequency shift. 3.3FREQUENCY-!\,10DULATED CWRADAR Theinability ofthesimpleCWradartomeasure rangeisrelatedtotherelatively narrow spectrum (bandwidth) ofitstransmitted waveform. 
 When normalized with respect to the square of the wavelength, the RCS patterns  of two perfectly conducting objects of identical shape but different size will be identi - cal if the objects are the same number of wavelengths in size. If a model is one-tenth  of full scale, for example, it should be measured at one-tenth of the full-scale wave - length (ten times the full-scale frequency). The RCS of the full-scale target may be  obtained from the scale-model measurements by multiplying the scale-model RCS  by the square of the ratio of the two frequencies. 
 Unsynchronized replies coming from themulti- pleinterrogation ofanear-by beacon may interfere with detection ofthe signals from one farther away atthe same azimuth. Itisdifficult to make adefinite statement about theextent oftheinterference because it depends somuch onthe characteristics ofthe radar set. The use of. 
 E. L. Cole et al., “ASR-12: A next generation solid state air traffic control radar,” Proc. 
 TION OF FREQUENCY IS   3F 3F FFFF   ¤ ¦¥³ µ´aa A     (ERE F AND F ARE THE START AND END FREQUENCIES OF THE SEGMENT  RESPECTIVELY   3 (Zn  IS THE PHASE NOISE SPECTRAL DENSITY RELATIVE TO THE CARRIER AT THE BEGINNING OF  THE SEGMENT AND @  IS THE SLOPE OF THE SEGMENT IN LOG 
 13.90 and b. Plots of this type give information about both the wind-speed and grazing-angle depen- dence of sea clutter for a given frequency, polarization, and wind direction. Fig- ure 13.9a and b is based on a blend of radiometer-scatterometer (RADSCAT) data at 13.9 GHz29 and measurements by Masuko et al. 
 AP-34, pp. 1034–1037, August 1986. 46. 
 In the receiver, frames are grouped into blocks called bursts. The duration of a  burst is approximately equal to the time taken for the 3 dB points of the antenna  azimuth beam to sweep past a point target; consequently, the number of pulses in  a burst is directly related to the instrumented range and the antenna rotation rate.  The echoes received during a burst are processed by a filter bank to extract the  radial velocities of targets and clutter. 
 (6)and (7)bracket the true value and differ from each other unimpor- tantly inpractical cases. Auseful approximation forWisgiven by w=1 1+(n–W)7’(8). SEC. 
 105, pp. 134-139.  23. 
 N. Mikhaylyukov, and I. P. 
 If the largest practical phase shift per  diode pair is 1/16, or 22.5", 32 diodes are required to shift the phase 360".  1'he hybrid-coupled phase shifter generally has less loss than the other two, and uses the  Icast rluttihcr of diodcs. It call \,c rnade to operate over a wide band. 
 However, people generally rotate images in an integer multiple of 90 degrees: 90, 180, 270. If we rotate the image by a random number of degrees, some problems may appear. As shown in Figure 8, when we rotate image 20 degrees, the black area may introduce a lot of disturbance into CNN training. 
 No further transparent regions aretobefound until wereach awavelength oftheorder of15microns (0.0015 cm). The oxygen absorption rises toahigh peak at5-mm wavelength; this has been quantitatively verined bydirect measurement. Atlonger lJ.H.VanVleck, ``Further Theoretical Investigations oftheAt,mospheric Absorp- tion ofMicrowaves,” RLReport No. 
 After all the pulses have been transmitted, multiple simultaneous receive beams  are formed with a receive beam located in each of the transmit beam positions. In this  method, each of the transmit beams has the full array gain. In order to have similar per - formance to the beam-broadening technique, the transmit pulse segment in each beam  position would be 1/ N times as long as the transmit pulse in the beam-broadened tech - nique, where N is the number of simultaneous receive beams. 
 13.4 beyond the point ~vhere the resolving po\ver ofthe eye ceases tobethe limiting factor (5-to7-in. magnetic tubes, 3-to5-in. electrostatic tubes). 
 11. McLeod, J.: The Axicon: A New Type of Optical Element, J. Opt. 
 SELECT 
 Thesizeoftheregions inwhichtheerror currents cannotbeconsidered independent isthecorrelation interval, C.Thesizeofthe correlation intervalaffectsboththemagnitude andthedirectional characteristic ofthespuri­ ousradiation thatresultsfromthepresence oferrors. ThefirsttermofEq.(7.31)represents theno-error radiation patternreduced bythe factor,exp-P".Thesecondtermdescribes thedisturbing patternandrepresents asourceof sidelobe energywhichdepends onthemean-square phaseerrorandthesquareofthecorrela­ tioninterval. Forsmallphaseerrors,whenonlythefirsttermoftheseries(n=1)needbe considered, Eq.(7.31)becomes (7.32) FromEq.(7.31),thereduction ingainonaxiscanbewrittenas (7.33) Beamdirectian r ){::----+-----y ---¢-~ Figure7.28Coordinate systemdefining theanglese,t/JofEq. 
 24.8  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 A self-screening jammer  (SSJ) is used to protect the carrying vehicle. This situation  stresses the capability of an ECM system relating to its power, signal-processing, and  ESM capabilities. Self-protection  (SP) decoy jamming is an off-board technique intended to create  angle deception by causing a missile seeker to transfer angle track from the target to  a decoy. 
 However, inaflexiblephased-array radar.thescanning oftheheampositions mightnotbeuniform. Thelikelihood ofoverdetec­ tionofatargetwilldependonhowthevolumeisscanned. Toavoidthisproblem thedetection decision mighthavetobedelayed untiltheneighboring beampositions havebeenscanned. 
 132. T. Nagler and H. 
 However, a  cannot be made arbitrarily large because the compressed pulse  tends to distort. Collins and Atkins15 discuss an extension of the tangent-based NLFM  for which the frequency modulation function is a weighted sum of tangent-based and  linear frequency modulation terms.  Figure 8.12 shows the frequency modulation-versus-time functions for a sine- based NLFM waveform with k = 0.6, a tangent-based NLFM waveform with a  = 2.5,  and an LFM waveform. 
 58. C. L. 
 15.12 have no a  priori  restrictions on surface heights. The statistical properties of the sea surface enter through the correlation coeffi - cient C(y) appearing under the integral sign in the exponential in the brackets, and by  expanding this exponential in Eq. 15.12, it may be written  σ ψ ψ0 2 4 22 1 122 2 42 ( ) ( )!( )( )=( )− =AkF ek nW kpk hn n n∞ ∞ ∑ (15.13) where  W k d e h Cn i k n ( )( ) [ ( )] 212 21 = −∞∞ ∫τ ττ  (15.14) Small-amplitude Approximation. 
 NUMBERED DELAY  SO  H)N  IS REALIZED USING A SINGLE DELAY AND SOME NUMBER OF DOUBLE  DELAYS 4HE IMAGINARY PART  H1N  OF THE IMPULSE RESPONSE  IN CONTRAST  HAS NONZERO COEF 
 46 WITH ITS TIME 
 When the scattering direction fs is aligned  along the shadow boundary where fi − fs = p , the diffraction coefficient X in Eq. 14.18  becomes singular, a meaningless result. When the scattering direction fs is aligned  along the specular direction where the local angle of reflection is equal to the local  angle of incidence, then fi + fs = p . 
 NOISE RATIO PER PULSE FOR THE  CELL 
  TO   O# )T WAS PREDICTED THAT THIS %)+ WOULD  BE CAPABLE OF TWO YEARS OF CONTINUOUS OPERATION WITH A  CONFIDENCE LEVEL 4WO %)+S WERE EMPLOYED IN #LOUD3AT ONE PRIME  ONE REDUNDANT  SO AS TO ACHIEVE A  CONFIDENCE OF MEETING THE TWO 
 STATE RADAR  AND ENUMERATES ITS ADVANTAGES AND WHY IT IS IMPORTANT 4HERE IT IS STATED THAT hONE OF THE PRINCIPAL ADVANTAGES OF AN !%3! IS THE ABILITY TO MANAGE BOTH POWER AND SPATIAL COVERAGE ON A SHORT 
 System calibration techniques and adaptive beamforming techniques can com - pensate for linear gain and phase deviations; however, as for the case of the LNA  nonlinearities described above, compensation for nonlinear characteristics is either  impractical or impossible when the cause of the nonlinear distortion is outside the  digitized bandwidth. Evaluation.  A thorough evaluation of all elements of the receiver is nec - essary to prevent unanticipated degradation of noise figure or dynamic range. 
 Based  on this oval, maximum and minimum detection ranges and the coverage area are  calculated, all as a function of RM. This procedure is also used to define bistatic  operating regions. Range Equation. 
 - "OERNER  h-EASURING POLARIZATION DYNAMICS OF THE  GENERALIZED (& SKYWAVE CHANNEL TRANSFER FUNCTION v  0ROC )NT 3YMP !NT AND 0ROP   )3!0    *APAN  !UGUST   4 ( 0EARCE  h2ECEIVING ARRAY DESIGN FOR OVER 
 NITUDE OF THE COUPLING IS INFLUENCED  BY THE DISTANCE BETWEEN THE ELEMENTS  THE PATTERN  OF THE ELEMENTS  AND THE STRUCTURE IN THE VICINITY OF THE ELEMENTS &OR EXAMPLE  THE RADIATION PATTERN OF A DIPOLE HAS A NULL IN THE  P    on DIRECTION AND IS OMNIDIRECTIONAL  IN THE P    n PLANE 4HEREFORE  IT CAN BE EXPECTED THAT DIPOLES IN LINE WILL BE LOOSELY  COUPLED AND PARALLEL DIPOLES WILL BE TIGHTLY COUPLED 7HEN AN ELEMENT IS PLACED IN AN ARRAY OF MANY ELEMENTS  THE EFFECTS OF COUPLING ARE SUFFICIENTLY STRONG THAT THE PATTERN AND IMPEDANCE OF THE ELEMENTS IN THE ARRAY ARE DRASTICALLY ALTERED. 
 In Figure 6, the ﬂight and look direction of ENVISAT-1 ASAR are indicated by black arrows. Two wind vectors were identiﬁed and shown as red arrows. The sea surface wind data was obtained from QuikSCAT on 27 April 2005 [ 27]. 
 RENT  * %Q    RESULTING IN AN EQUIVALENT SURFACE CURRENT REPRESENTED BY  *N ( r}   .OW  CONSIDER A GENERALIZED REFLECTOR SURFACE AS SHOWN IN &IGURE  4HE SUR 
 59-60  Color CRTs, 357  Complex angle monopulse, 176  Computer control of array radar. 322-328  Cone sphere, radar cross section of. 35-37  Conformal arrays, 330-33 1  Conical scan, 155.- 159, 182- 183  Conopulse. 
 P. Batlivala: Diurnal Variations of Radar Backscatter from a Vegetation Canopy,  IEEE 7'ro11s., vol. AP-24, pp. 
 TION SOURCES #)32 NET  SOMETIMES CALLED THE  'LOBAL )NFORMATION 'RID ')'     ! MAJOR USE OF RADAR AND AIRCRAFT DATA LINKS IS TO PROVIDE TOTA L SITUATIONAL AWARENESS    "Y USING ON 
 Ê, ,Ê 
   
 VOI. 10, pp. 109- 118, 1954. 
 D. P. Morgan, “Surface acoustic wave devices and applications,” Ultrasonics , vol. 
 This can be obtained from the analogous spatial doppler frequency shift that expands or compresses the apparent antenna radiation pattern (just as the radial component of velocity can expand or compress the time waveform of a radar signal reflected from a moving target to produce a temporal doppler frequency shift). A measurement of tangential velocity requires a wide-baseline antenna, such as an inter- ferometer. The measurement of tangential velocity has not seen application because the required baseline is often too wide for practical purposes. 
 Closing velocity is Vc = VM cos a + VT cos p. For the head-on case, all angles become zero and Vc = VM + V7-, with the result that fd = (/o/c)2Vc. The constant of proportionality f^/c at X band (approximately 10 GHz) is 10 Hz/(ft/s), and hence the rule of thumb is that target doppler is 20 Hz for each foot per second of closing velocity at X band. 
 (Z BAND RELATIVE TO  7  D"7  IS GIVEN AS A FUNCTION OF FREQUENCY FOR THREE DIFFERENT SOURCES OF NOISE GALACTIC  ATMOSPHERIC  AND ANTHROPOGENIC 4HE PRACTICE IN USE IS TO SELECT THE LARGEST 4HIS IS A WINTER DAYTIME EXAMPLE AT A 5NITED 3TATES EAST COAST LOCATION 4HE THREE STRAIGHT LINES ARE ESTIMATES OF ANTHROPOGENIC NOISE FOR THREE DIFFERENT TYPES OF SITES 4HE SHAPE OF THE ANTHROPOGENIC CURVES IS DESCRIBED BY THE EQUATIONS  . O   n  n  LN F    RESIDENTIAL   .O   n  n  LN F    RURAL   .O   n  n  LN F    REMOTE    WHERE THE FREQUENCY F IS IN MEGAHERTZ AND LN INDICATES THE NATURAL LOGARITHM 4HESE FREQUENCY TRENDS APPROXIMATE MANY MEASUREMENTS OF HUMAN 
 39. L. J. 
 Forexample, theelements mightbearranged onthesurfaceofacylinder toobtain3600 coverage (360°coverage mayalsobeobtained withanumber ofplanararrays).Theradiating elements mightalsobemounted onthesurfaceofasphere,orindeedonanobjectofany. shape, provided the phase at each element is that needed to give a plane wave when the  radiation from all the. elements is summed in space. 
 This beam is  tilted to minimize illumination of the ground. As the transmitted pulse travels beyond the  ground clutter range (typically 50 miles or greater) the receiver is switched to the lower beam  for long-range reception. In the ARSR-3 the ratio of the lower-beam gain in the direction of  the horizon to that of the upper-beam gain in the same direction is 16 dB.'" (The lower beam  has its half-power point on the horizon.) The antenna elevation pattern is shaped to have at  the higher angles a greater gain than would be normal with a cosecant-squared pattern. 
 TRACK SPREAD OF THE ANTENNA PATTERN  WHICH  OF COURSE  IS PROPORTIONAL TO RANGE ,ET THIS BE THE CANONICAL CASE !ZIMUTH RESOLUTION MAY BE SHARPENED ONLY BY INCREASING DOPPLER BANDWIDTH  WHICH CAN BE DONE IN ONE OF TWO WAYS INCREASING THE ANTENNAS BEAMWIDTH OR INCREASING THE SPREAD OF ASPECT ANGLES WITHIN WHICH THE ANTENNA ILLUMINATES A GIVEN PORTION OF THE SCENE 4HE LATTER IS THE BASIS FOR 3POTLIGHT 3!2  o IN WHICH THE ANTENNA IS STEERED TO DWELL ON THE INTENDED AREA  AS THE RADAR PASSES  THUS CREATING A WIDER TOTAL DOPPLER BANDWIDTH AND A LONGER SYN 
 Inthis limiting case the incident field isconsidered homo- geneous over theextension ofthetarget. Inthehomogeneous field the —yct sphere becomes anelectric dipole with adipole moment pe ,where (2) and cisthe dielectric constant. The field ofthis dipole, observed ata distance rinthe wave zone and inadirection perpendicular tothe polarization, is ‘(,–.() ()2Z-cl)~A ek ART= : p—. 
 - .- 0 . - u 0  L -30- al > . - t 0 - w a -40-  - 50  Figure 7.1 Radiation pattern for a particular paraboloid reflector antenna illustrating the main beam and  the sidelobe radiation. 
 FED SERIES FEED "ECAUSE THE BANDWIDTH PERFORMANCE OF EACH IS COMPARABLE  THE  OPTICAL 
 O'Meara, T. R.: The Synthesis of "Band-Pass," All-Pass, Time Delay Networks with Graphical Approximation Techniques, Hughes Aircraft Co. Res. 
 independent scatterers.. 472 INTRODUCTION TO RADAR SYSTEMS  where P, = transmitter power  G = antenna gain  A, = antenna effective aperture  R = range  a, = clutter cross-section, which is equal to  ac = aOA, = a0ROB(cr/2) sec 4  where c = velocity of propagation. With this substitution the radar equation for surfact: clutter  is  P, G/l,(rOO,(~-r/2) scc 4 c = - - - .. 
 May, 1960.  75. Edelberg, S., and A. 
 .\tlarge distances from thetarget thecomponent oftheelectric field parallel tothereceiving %–Cf) dipole can bewritten inthe form Eoe:(2–co+s~ +termsr decreasing faster than r–l,where Enistheamplitude oftheincident plane wave, S/risthe amplitude ofthe only important part ofthe scattered wave, Athe radar wa~-elength, cthe velocity oflight, and tthe time. Usually 13,and Scontain complex phase factors; Sisingeneral afunction ofthe scattering angles. Inthe following discussion the symbol SEis used todenote the value ofSinthe direction ofthereceiver. 
 FREQUENCY NOISE CAN CAUSE THE AMPLITUDE TO CHANGE DURING THE TIME TAKEN TO  MOVE THE ANTENNA BEAM FROM ONE POSITION TO THE NEXT %VEN IF THE TARGET IS ON AXIS  HIGH 
 RENT DIRECTION IS DUE TO THE NONRECIPROCAL NATURE OF THE DEVICE !S MENTIONED  EARLY DEVICES SATURATED EACH BIT SO THAT A FERRITE TOROID AND ELECTRONIC DRIVER WERE REQUIRED &)'52%   $IODE PHASE 
 Suppose atarget appears atAonthevertical beam atanazimuth selected by the operator. Video output from the vertical beam appears onthescope for 10° ofazimuth rotation cen- tered ontheselected azimuth. It isthen blanked outand slant video substituted. 
 OGY DEMONSTRATION 4HE MAIN PAYLOAD INSTRUMENTATION WAS COMPRISED OF FOUR OPTICAL CAMERAS  INCLUDING ONE WITH A LASER ALTIMETER -AJOR NEW INFORMATION ABOUT THE -OON WAS PROVIDED FROM #LEMENTINES DATA COLLECTED DURING ITS  DAYS IN LUNAR ORBIT #LEMENTINE IS RELEVANT TO THIS CHAPTER BECAUSE OF A UNIQUE BISTATIC RADAR EXPERIMENT  CONDUCTED WITH THE 3 BAND  CM  2& DATA SYSTEM 4HE LUNAR  SOUTH POLE WAS ILLU 
 The total number of filters implemented to cover all doppler frequencies is a design  option trading straddling loss at the filter crossover frequencies against implementa - tion complexity. An example of a complete doppler filter bank implemented with nine  uniformly spaced filters is shown in Figure 2.55. The performance of this doppler filter  bank against the clutter model considered in Figure 2.25 is shown in Figure 2.56. 
 ,,", 2ECEIVER 4HERMAL .OISE  4HE ANGLE ERROR CAUSED BY RECEIVER THERMAL NOISE IN A  MONOPULSE TRACKING SYSTEM IS   SQ TBT" MR N K" 3 . F          WHERE KM IS THE ANGLE 
 The ratio of the peak to the rms error is found experimentally  to be about 3 : 1. This truncation of errors occurs since large errors usually are corrected in  manufacture.  The effect of errors in array antennas and further discussion of errors in continuous  apertures is given in Sec. 
 It is also the most common types of pulse compression   and is in wide use. Sweeping the carrier frequency throughout  a pulse results in  every part of a pulse being  distinct  and  discernable . This enables pulse compression techniques to be  utilized  in the receiver , which is a very powerful radar  technique for impr oving range resolution and making more  efficient use of transmit power. 
 1731–1740, 1966. 49. H. 
 With  scanning, lobes that were originally in imaginary space may move into real space if  the element spacing is greater than l /2. As the array is scanned away from broadside,  each grating lobe (in sin q  space) will move a distance equal to the sine of the angle of  scan and in a direction determined by the plane of scan. To ensure that no grating lobes  enter real space, the element spacing must be chosen so that for the maximum scan  angle qm, the movement of a grating lobe by sin qm does not bring the grating lobe into  real space. 
 (2.30) refers to an actual (thermodynamic) temperature. The temperature defined by Eq. (2.31) is semifictitious because of the nonthermal origin of some of the noise. 
 1SeeSees.13.15to13.18. The abbreviation “PPI” isused interchangeably to represent both thedisplay andtheequipment (plan-position indicator). Abbrevia- tions forother types ofindicators areused inthesame way.. 
 At short range, however, the angular  rates are likely to be large so that a wide tracking bandwidth is needed in order to follow the  target properly. The loss in sensitivity due to the greater bandwidth is offset by the greater  target signal at tlie sliortcr ranges. The bandwidth should be no wider than necessary in order  to keep the angle errors due to target scintillation, or glint, frorn becoming excessive. 
 Slight modification8'13 is needed when the basic radar has the balanced method (Fig. 14.9) of generating the offset required for the first IF amplifier. The servo amplifiers have response from dc to some frequency well below the doppler band of interest. 
 11.3 that account for surface orientations not included in Table 11.1. Complex Objects. Objects like antennas, insects, birds, airplanes, and ships can be much more complex than those discussed above, either because of the multiplicity of scatterers on them or because of the complexity of their surface profiles and dielectric constants. 
 Acous. Soc. Am., vol. 
 Hence, ontheaverage, aplot was obtabed oneach track once every 1.8rnin, which isconsidered tobefairly continuous tracking. Close Control bytheFDP.—At the turn ofthe year 194041, the Luftwaffe abandoned itsdaytime attacks onEngland and turned tonight bombing, the attacking aircraft operating individually. This ledto~he development bytheBritish ofanelaborate system ofnightfighter defense which hasbeen described elsewhere. 
 "&)"* ,-*"  "&)"* ,-*" 
 02& RADAR !LSO SHOWN IN &IGURE  IS THE SINGLE 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°£ !NTENNAS AND 4RANSMITTERS  !NTENNAS FOR THE PIONEERING SPACE 
 ING DETECTION OF MOVING TARGETS IN CLUTTER 4HE HIGH 
             
 Since the output of the mixer  74INTRODUCTION TORADAR SYSTEMS usualdopplerspectrum ofinterest. 31,69Thenormalantenna isolation plusfeedthroughnul­ lingusuallyreduces th~AMcomponents belowreceivernoiseinmoderate powerradars.FM sidebands areusuallysignificantly greaterthanAM,butdecrease withincreasing offsetfrom thecarrier.5Thecharacter ofFMnoiseintheleakagesignalisalsoaffectedbystabilizing the outputfrequency oftheCWtransmitter andbyactivenoise-degeneration usingamicrowave bridgecircuittoextracttheFMnoisecomponents. Thesearethenfedbacktothetransmitter insuchamannerastoreducetheoriginalfrequency deviation.31Ithasbeensaid69that experience indicates thatasatisfactory measurement ofAMnoiseoverthedopplerfrequency bandprovides assurance thatbothAMandFMnoisegenerated bythetubearewithin required limits. 
 LOBES CAN BE REDUCED AND SPECTRAL LEAKAGE CAN BE CONTROLLED #ONTROLLING THE PHASE DISCONTINUITY FROM THE END OF ONE SWEEP TO THE BEGINNING OF THE NEXT PROVIDES ANOTHER DIMENSION IN WHICH THE WAVEFORM PROPERTIES CAN BE OPTIMIZED &URTHER GENERALIZATION OF THE &- 
 J. McAulay, “A theory for optimum MTI digital signal processing,” MIT Lincoln Laboratory,  Lexington, MA, Report no.1972-14 Part I, Part II, Supplement I, February 22, 1972.  6. 
 22.26  22.6 SBR Future Possibilities  .........................................  22.26  Rendezvous Radar Mi ssions  ..............................  22.26  Remote-Sensing Missions  ................................. 
 RANGE AIRBORNE WEATHER RADARS OFTEN EMPLOY BEAMWIDTHS OF nn AS A COMPROMISE BETWEEN WAVELENGTH REQUIREMENTS AND ANTENNA SIZE CONSTRAINTS WHEREAS SPACEBORNE RADARS MAY USE A FRACTION OF A DEGREE BEAMWIDTH TO RETAIN USABLE HORIZONTAL RESOLUTION AT TYPICAL LONG RANGES n KM  /PERATIONAL WEATHER RADARS NORMALLY ARE CAPABLE OF SHORT AND LONG PULSE OPERATION  IN THE RANGE OF   MS TO ABOUT   MS AND 02&S BETWEEN  AND  (Z FOR LONG 
 Uniitations ofmillimeter waves.Theapplication ofmillimeter wavelengths hasbeenlimited bytheavailability ofsuitahle components. Transmitter powersarelow,receiver noisefigures arehigh.transmission lineslossy.andequipment generally costlyandunreliable. Thereis reasontobelieve, however. 
 The output of the  amplifier would then be independent of the range, for constant target cross section. Amplifier  response shaping is similar in function to sensitivity time control (STC) employed in conven­ tional pulse radar. However, in the altimeter, the echo signal from an extended target such as  the ground varies inversely as the square (rather than the fourth power) of the range, since the . 
 DETECTOR OUTPUT EQUAL TO ANGLE ERROR TIMES THE ANGLE SEN 
 Goodrich, R. F., et al.: Diffraction and Scattering by Regular Bodies—I: The Sphere, University of Michigan, Dept. Electr. 
 73-78, July, 1979.  50. Staprans, A.: Linear Beam Tubes, chap. 
 A limita-  tion of the EBS, not found with other semiconductor devices, is that it requires a power supply  of 10 to 15 kV as well as a cathode heater supply.  Methods for employing solid-state transmitters. There are at least three metllods f$r employing  solid-state devices as radar transmitters: (1) direct replacement of a vacuum tube, (2) multiple  modules in an electronically steered phased-array radar with the power combined in space,  and (3) multiple modules in a mechanically scanned array with the power combined in space. 
 PHASE SHIFTER APPLICATIONS v -ICROWAVE *  VOL   PP n  3EPTEMBER    2 ! 0UCEL ED   -ONOLITHIC -ICROWAVE )NTEGRATED #IRCUITS  .EW 9ORK )%%% 0RESS     * , 0OIRIER  h!N ANALYSIS OF SIMPLIFIED FEED ARCHITECTURES FOR --)# 42 MODULE ARRAYS v  2OME  !IR $EVELOPMENT #ENTER 2EPT 2!$# 
 associated with the noncoherent detection of targets in Rayleigh noise. (NOTE: If the quadrature components are gaussian-distributed, the envelope is Rayleigh- distributed and the power is exponentially distributed.) Marcum's most important result was the generation of curves of probability of detection (PD) versus signal- to-noise ratio (SIN) for a detector which sums N envelope-detected samples (ei- ther linear or square-law) under the assumption of equal signal amplitudes. How- ever, in a search radar, as the beam sweeps over the target, the returned signal amplitude is modulated by the antenna pattern. 
 Its output signals gotothe input crystal ofthe 15-Mc/sec delay line, and also tothe “undelayed” channel ofatwo- channel amplifier. The “delayed” channel oftheamplifier receives the output signal from thedelay line and amplifies it. The two channels of. 
 Range, Pulse-repetition Frequency, and Speed ofScan—It is thefunction ofmost radar sets tosearch continually through some region inspace byscanning. Naturally the radar designer strives always to enlarge the region which can thus besearched, toincrease the rapidity with which itcan becompletely explored, and toimprove theability to distinguish detail within the region. Inthis endeavor heismade acutely aware oftwo ofthefundamental limitations ofpulse radar which canbeblamed respectively onthefinite velocity oflight and thenecessity offunneling allinformation insequence through asingle electrical channel. 
 RECEIVER SYSTEM USING THE SAME !$# &IGURE  SHOWS A BLOCK DIAGRAM OF A TYPICAL DIGITAL BEAMFORMING SYSTEM %ACH  ANTENNA OUTPUT PORT  BE IT FROM AN ELEMENT OR A SUBARRAY  IS FOLLOWED BY A DIGITAL  &)'52%   4YPICAL DIGITAL BEAMFORMER                
 This portion of the leakage pulse is  termed thepat. Damage to the receiver front-end may result when either the energy contained  within the spike or the power in the flat portion of the pulse is too large. "Typical" TR tubes  might have a spike leakage of one erg or less and might provide an attenuation of the incident  transmitter power of the order of 70 to 90 dB. 
 1788-1789, October, 1969.  8. Shrader, W. 
 Sea roughness can be taken into account by using the work of Barrick.54 Path-loss descriptors such as shown in Fig. 24.28 can be used to estimate perfor- mance. For example, consider a radar at 5 MHz with an average power of 10 kW (40 dBW), a transmit-receive antenna gain product of 15 dB, and a target at 100 nmi with an RCS of 20 dBsm; then the received power Pr = 40 + 15 + 20 - 222 = - 147 dBW By using the January nighttime noise as given in Fig. 
 27.5 ADDITIONAL SYSTEM CONSIDERATIONS In this section a number of considerations peculiar to synthetic aperture radar are discussed. Some are additional performance requirements on the components of the system; some are concerned with system aspects. Antenna. 
 Even with beam-splitting, qR is  the critical parameter establishing accuracy of the RR estimate, since, as in the monostatic  case, its error is proportional to target range. A full error analysis of Eq. 23.13 is given  in Section 5.2 of Willis.1  No bistatic radar operating autonomously has been shown to  provide adequate location of air or space targets without employing receive apertures  comparable in size to monostatic receive apertures used for those purposes. 
 MITTERS   AND THE ($46 
 Toinsure rapid breakdown at thebeginning ofeach pulse, aSUP plyofions inthegapismaintained by acontinuous auxiliary dis- charge inside one ofthe cones. This requires anextra electrode, known asthe ‘‘keepalive” elec- trode, which draws about 150pa from an800-volt supply. Abal- last resistor drops the voltage to about 400 volts atthe electrode itself. 
 vol. 34.  no. 
 1630-1635, September 1960. 38. Garbacz, R. 
 ERROR 
 2'0/ 4HREE TYPES OF TARGETS NUMBERED     AND   HAVE BEEN CONSIDERED TARGET  REPRESENTS A CARGO AIRCRAFT WHILE TARGETS  AND  REPRESENT FIGHTERATTACK AIRCRAFTS WITH A MUCH HIGHER DEGREE OF MANEUVERABILITY &OR EACH EXPERIMENT  THE FOLLOWING RESULTS ARE DISPLAYED NUMBER OF LOST TARGETS OVER  -ONTE #ARLO TRIALS   4 S RADAR SAMPLING TIME    4AVE AVERAGE FRACTION OF TIME REQUIRED BY THE RADAR FOR TARGET  TRACKING    0- AVERAGE POWER   POSITION ERROR  AND VELOCITY ERROR 4ABLE  SHOWS  SIMULATION RESULTS FOR THE )NTERACTING -ULTIPLE -ODEL )--  TRACKING ALGORITHM IN  THE ABSENCE OF %#-S 4ABLES  AND  REPORT THE RESULTS IN  THE PRESENCE OF 3/*   WITHOUT AND RESPECTIVELY WITH ! 
 A. S. Gilmour, Jr., Microwave Tubes , Norwood, MA: Artech House, 1986, Sec. 
 J. Plant (eds.),  Dordrecht, Netherland: Reidel, 1989. 13. 
 LOADED INTO THE ONBOARD 3!2 CONTROL PROCESSOR FOR EACH THREE 
 PULSE CANCELER  e BUT THE PRINCIPLE STILL REMAINS THAT FIXED CLUTTER IS REJECTED BY THE ZEROS IN   THE CANCELER TRANSFER CHARACTERISTIC 4HIS ENABLES PHASED ARRAY RADARS TO HAVE GOOD CLUT 
 Also, rather than the original large high-aspect-ratio antenna typical of  space-based SARs, Magellan  was obliged to use a spare circular communications  antenna left over from a previous mission. Whereas these may sound like benign  if not trivial modifications, they necessitated paradigm-shifting innovations by the  SAR design team. Antenna . 
 The matched filter output SNR is given by*  S NE N()=mf2 0 (8.45) where E is the energy of the received bandpass signal at the matched filter input ( J),  and N0 is the one-sided noise power spectrum at the matched filter input (W/Hz).  Filter Matching Loss.  Filter matching loss Lm is the loss in SNR that results when  a signal is not processed using a matched filter. 
 sleeve covered the gap to prevent the arc spreading down the electrodes and taking longer to extinguish. 2.2.5 Performance of ASV Mk. II One feature of many early radar trials was the great variation in performance that was observed. 
 We have seen enough of radar systems to realize that  a ‘short, sharp shout’ is the fundamental of all transmis-  . +  ae 84 HOW RADAR WORKS  sion in this way, and therefore the major task of all  modulator circuits at the transmitting end must be to  create not a gentle sine wave to modulate the C.W., but  as ‘vertical’ a square wave as possible to cause a nearly  instantaneous burst of energy, and then a cut-off again  as nearly instantaneously as possible. We need many  Circuits in the transmitter modulator, first to form a  square pulse with a wave-form having a leading edge as  nearly vertical as possible to produce a sudden burst of  energy. 
 POLARIZED RADAR  THE RELATIVE PHASE BETWEEN THE TWO POLARIZED DATA SETS IS DISCARDED )N %ARTH 
 DEPENDENT EFFECT WITH THE OTHER COMPONENTS  PROVIDES AN ESTIMATE OF THE SPECTRUM OF RETURNS FROM STABLE CLUTTER  WHICH IS THEN MODIFIED BY THE RECEIVER FILTERS AND INTEGRATED TO OBTAIN THE RESI 
 Circulator andreceiver protector. Theferritecirculator47isathree-orfour-port devicethat can,inprinciple. offerseparation ofthetransmitter andreceiver without theneedforthe conventional duplexer configurations ofFigs.9.5to9.7.Thecirculator doesnotprovide sufficient protection by itself andrequires areceiver protector asinFig.9.9.Theisolation betweenthetransmitter andreceiver portsofacirculator isseldomsufficient toprotectthe receiver fromdamage. 
 Ifseveral fade points aredetermined, the height can beinferred with better accuracy. This method has been used extensively with the 200-M c/sec aircraft- search radar used onnaval vessels. Itisespecially useful ~vith this type ofradar because theelevation pattern can bewell known (the ocean isa good reflector, and theantenna height isdetermined bythe class ofship and notbytheshape oftheterrain), and because aradial approach toa task force isgenerally chosen byeither enemy orfriend. 
 45. Swerling, P.: Detection of Fluctuating Pulsed Signals in the Presence of Noise, I RE Trans., vol. IT-3,  pp. 
 6, pp. 150 -152, June  1, 1957.  20. 
 392 RFCOMPONENTS [SEC. 11.1 line, such asmight beintroduced byachange indimension ofone ofthe conductors, orany change ingeometry introduced byasharp bend, or byadent oranobstacle inthe line, will produce areflection. The reflected energy travels back toward thesource. 
 Radar System Engineering  Chapter 7 – CW and FM -CW Radar  48       Figure 7.9  FM CW Radar system – block diagram   Figure 7.10 shows a microwave door opener, which has become implemented as CW Doppler  Radar.     Figure 7.10  Microwave door opener: 24 GHz CW Doppler Radar.   . 
 The soiid part of thecurve isbased onextensive direct measurements. These confirmed themain features ofthe theoretical predictions,l onthe basis ofwhich theremainder ofthe curve has been sketched in;one cannot, however, rely onthequantitative accuracy ofthe dotted part ofthe curve. The curve isplotted foranatmosphere containing 10gofwater vapor per cubic meter. 
 Solving forthe height and introducing thefact that f.isquantized insteps off,,wefind fortheerror 6h 1Itisbeats ofthissort, which may bedescribed asduetotime-delay demodulation ofF.M,that areregarded asspurious signals inthesystem described inSec. 5.6and that must beavoided byreducing FM ofthetransmitter tothelowest possible value. SEC. 
 The output terminals produce the sum and difference of the two amplified input signals. Since DPCA compensates for the complex signal, both amplitude and phase in- formation must be retained. Therefore, these operations usually occur at RF or IF. 
 ONLY CELLS )T ACCOMPLISHES THIS BY TRANSMITTING  A COHERENT BURST OF PULSES THAT ARE SUBSEQUENTLY RECEIVED BY EACH OF THREE LINEARLY DIS 
 The aspect entropy of trihedrals is in the range [0.7878, 0.7918]. The aspect entropy of dihedrals is in the range [0.6805, 0.7019]. The aspect entropy of the top-hat is 0.9927. 
 Weckwerth, C. R. Pettet, F. 
 Scptcmher, 1972.  25 Taylor. J. 
 lllF. FLITTRONICAl.l.Y STEFRED PHASED ARRAY ANTENNA IN RADAR 331  cal array also attracts attention when hemispherical coverage is desired. In principle. 
 TYPE TRACKING RADARS  RANGE MEASURE 
 Back oftheir development layhalf acentury ofradio development forcommu- nication purposes, and ahandful ofearly suggestions that, since radio waves areknown tobereflected byobjects whose size isoftheorder ofa wavelength, they might beused todetect objects infogordarkness. The fact that radio waves have optical properties identical with those associated with ordinary visible light was established byHeinrich Hertz in1886, inthefamous series ofexperiments inwhich hefirst discovered radio waves. Hertz showed, among other things, that radio waves were reflected from solid objects. 
 Δ  ψbeam 1 ψ sum Σ θbeam 2 θ diff. Δ θ total sum Σazimuth elevation    Figure 13.7  Two-plane ( ψ−θ) receiving monopulse circuit.     The summation channel is evaluated as in normal pulse Radar for the measurement of the  range and the velocity. 
 LATITUDE LOCATION   4YPICALLY  THE DIURNAL VARIATION REQUIRES A RADAR TO  VARY ITS OPERATING FREQUENCY BY MORE THAN AN OCTAVE IN FREQUENCY TO MAINTAIN  
 12.Sa. (Variations of the refractive index in the  horizontal plane may also exist, but they do not materially alter the bending.)  Refraction of radar waves in the atmosphere is analogous to bending of light rays by an  optical prism. The path of the radar waves through the atmosphere may be plotted using  ray-tracing techniques, provided the variation of refractive index is known. 
 The Taylor illumination is somewhat similar to a cosine squared on a pedestal and  is readily implemented. The Bayliss illumination is a derivative form of the Taylor  illumination and is also readily implemented. It should be noted that in many phased  arrays the sidelobe performance for the difference pattern is comparable to that of the  sum pattern. 
   PP n    " ! - "OUMAN AND ( 7 * VAN+ASTEREN   'ROUND 
 100, pp. 13681–13698, 1995. 179. 
 The spectrum of  a pulsed (gated) signal is different from CW. The resulting noise, the gated noise, can  be much different from the CW noise, especially for low duty cycle waveforms and  noise close to the carrier. It is preferable to make noise measurements on equipment  ch04.indd   28 12/20/07   4:52:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Angle-fluctuation noise varies inversely with range; receiver  noise varies as the square of the range; and amplitude fluctuations and servo noise are  independent of range. This is a qualitative plot showing the gross effects of each of the factors.  Two different resultant curves are shown. 
 N. Colwell, D. S. 
 THE 
 M. I. Skolnik, Introduction to Radar Systems , 3rd Ed., New York: McGraw Hill, 2001, p. 
 Duringreception, thetransmitter isoffandneithertheTRnortheATRisfired.Theopen circuitoftheATR,beingaquarterwavefromthetransmission line,appears asashoftcircuit acrosstheline.Sincethisshortcircuitislocatedaquarterwavefromthereceiverbranch-line, thetransmitter iseffectively disconnected fromthelineandtheechosignalpowerisdirected to thereceiver. Thediagram ofFig.9.5isaparallel configuration. Seriesorseries-parallel configurations arepossible.37 Thebranch-type duplexer isoflimited bandwidth andpower-handling capability, andhas generally beenreplaced bythebalanced duplexer andotherprotection devices.Itisused,in spiteoftheselimitations, insomelow-cost radars. 
 1 1, pp. 94 - 100, 1955.  81. 
 A new range compression technique is applied to the ISAR complex signal through summation of time recorded ISAR signals in all frequency channels. In case the registration spectral resolution is not satisfactory, which limits the unambiguous time interval of coherency, interpolation in the frequency domain is required. 115. 
 Since the ﬂow velocity has two components, two constraints are needed to solve for it. The brightness constancy constraint assumes that the brightness of a small area in the image remains constant as the area moves from image to image. Image brightness at the point ( x,y) in the image at time tis denoted here as I(x,y,t). 
 UP %ACH OF THESE DIRECTIONAL MODES CAN BE SET WITH TARGET TRACKING VECTORS SHOWN AS RELATIVE  TO THE MOTION OF THE  SHIP  THE GROUND   OR THE AVERAGE SEA MOTION ÓÓ°ÎÊ  / 
 Figure 7. B-SAR Data Processing block diagram. 3.3. 
 Seeker opera- tion then proceeds as for the semiactive case until target intercept. Passive Seekers. Three passive operating modes have been employed for missile guidance: antiradiation homing (ARH), home-on-jam (HOJ), and radiometric. 
 The RCS of the ARM becomes greater as the wavelength of the  radar approaches the missile dimensions, causing a resonance effect.3 A low-frequency  radar is somewhat less vulnerable to an ARM attack owing to the difficulty of imple - menting a low-frequency antenna with the limited aperture available in the missile.151  However, low-frequency radar has poor angular resolution. Tracking Radars.  Tracking radars provide good resolution and precise measure - ment of the kinematic parameters (position, velocity, and acceleration) of targets. 
 IEEE T rans. Aerosp. Electron. 
 79, no. 10, pp. 1551 -1558, Oct. 
 Therefore, we only need to pay attention to the off-nadir angel of PALSAR while estimating the VTEC. T able 2. Observing time and positions of three instruments. 
 Practically, it is suggested that it be applied only for ele- vation angles such that <|>/cos Qe is less than about 90°.) This formula is based on the properties of spherical geometry. The formula also assumes that the beam maximum is tilted upward at the angle 6e, but it can be applied with negligible error if Qe is only approximately equal to the beam tilt angle. The formula for the number of pulses within the half-power beamwidth for an azimuth- and elevation-scanning radar (which can be applied with minor modifi- cation to a radar scanning simultaneously in any two orthogonal angular direc- tions) is M= *JP (2.17) 6OVyRPM cos O6 where <j> and B are the azimuth (horizontal-plane) and elevation (vertical-plane) beam widths in degrees, Qe is the target elevation angle, o>v is the vertical scanning speed in degrees per second, and tv is the vertical-scan period in seconds (in- cluding dead time if any). 
 Phillips, “Spectral and statistical properties of the equilibrium range in wind-generated  gravity waves,” J. Fluid Mech ., vol. 156, pp. 
  AND ELEVATION 
 QUENCIES  AND SO ON %-#/. IS A TECHNIQUE FOR THE MANAGEMENT OF ALL %- RADIA 
 .OISE 2ATIO  4HE ACCURACY OF ALL RADAR MEASUREMENTS  AS WELL AS THE  RELIABLE DETECTION OF TARGETS DEPENDS ON THE RATIO  %. O  WHERE % IS THE TOTAL ENERGY  OF THE RECEIVED SIGNAL THAT IS PROCESSED BY THE RADAR AND  .O IS THE NOISE POWER PER  UNIT BANDWIDTH OF THE RECEIVER 4HUS  %.O IS AN IMPORTANT MEASURE OF THE CAPABILITY  OF A RADAR /PERATION WITH -ORE 4HAN /NE &REQUENCY  4HERE MAY BE IMPORTANT BENEFITS  WHEN A RADAR IS ABLE TO OPERATE AT MORE THAN ONE FREQUENCY &REQUENCY AGILITY USUALLY  REFERS TO THE USE OF MULTIPLE FREQUENCIES ON A PULSE 
 This assumption is in <lisagrt:cdlcnt with the  experimentally observed refractive-index structure of the atmosphere at heights above l km.1 7  The variation of refractivity with altitude is found to be described more nearly by an exponen­ tial function of height rather than the linear variation assumed by the 1 earth model or any  model of constant effective earth's radius. A more appropriate refractivity model is one in  which the refractivity varies exponentially with height,12•17  · N = N, exp ( -ce(h -h.,)] (12.12)  where N, = refractivity at surface of earth  h = altitude of target  h, = altitude of radar  Ce= ln (N,/ N 1) = a constant which depends upon value of Ns and Ni, the latter being refrac­ tively at altitude of 1 km  It is found that the exponential model gives a more accurate determination of the effects of  atmospheric refraction than does a linear model.  The use of the correct atmospheric model is quite important in a height-finder radar;  especially for targets at long ranges.12• 17 • 18 Refraction causes the radar rays to bend, resulting  in an apparent elevation angle different from the true one. 
 ON DWELL TIMES BECOME PROHIBITIVE AND THE SCAN CENTER IS FILLED WITH REAL BEAM MAPPING 4HE REAL BEAM USES THE SAME RANGE RESOLUTION  BUT BECAUSE RETURNS FROM THE ENTIRE BEAM ARE USED  SOME AMPLITUDE EQUALIZATION IS REQUIRED TO PROVIDE UNIFORM CONTRAST AND BRIGHTNESS ACROSS THE WHOLE MAP 3OME EFFORT IS MADE  &)'52%  $OPPLER BEAM SHARPENING $"3  COMPARISON TO 3!2 .   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°Îx TO MATCH FILTER BOTH IN RANGE CLOSURE AND PHASE HISTORY  THE DOPPLER SPREAD SINCE ISO 
 Foster, J. S.: A Microwave Antenna with Rapid Saw-Tooth Scan, Cmwdiw1 J. of Ph}'s .. 
 AN INTRODUCTION AND OVERVIEW OF RADAR  1.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 on transmit; that is, it is directive and has a narrow beamwidth; (2) collects the received  echo energy from the target; (3) provides a measurement of the angular direction to the  target; (4) provides spatial resolution to resolve (or separate) targets in angle; and (5) allows  the desired volume of space to be observed. The antenna can be a mechanically scanned  parabolic reflector, a mechanically scanned planar phased array, or a mechanically scanned  end-fire antenna. It can be an electronically scanned phased array using a single transmit - ter with either a corporate feed or a space-feed configuration to distribute the power to  each antenna element or an electronically scanned phased array employing at each antenna   element a small solid-state “miniature” radar (also called an active aperture phased array ). 
 Simulating the impacts of ionospheric scintillation on L band SAR image formation. Radio Sci. 2012 ,47, RS0L20. 
 No. 105. Rtdar.- -  Prc~sotrr arrd Frttrrri~, London. 
 VELOCITY  CONTOURS ARE CIRCULAR CONES WITH THE RADAR AT THE VERTEX AND THE AXIS ALONG THE PLATFORM  VELOCITY VECTOR #OURTESY OF 3CI4ECH 0UBLISHING  )NC  . 
 VIDE MATCHED 
 IEEE T rans. Geosci. Remote Sens. 
 The State-of-the-Art in Ship Detection in Synthetic Aperture Radar Imagery ; DSTO Information Sciences Laboratory: Edinburgh, Australia, 2004. 3. Dong, G.; Kuang, G.; Wang, N.; Wang, W. 
 ¤ ¦¥³ µ´  PS S    4HIS SPECTRUM IS NORMALIZED TO HAVE UNIT POWER  AND THE VELOCITY PARAMETERS HAVE  BEEN CONVERTED TO (Z USING THE DOPPLER EQUATION  MM FV FV    L SS L    &)'52%  0ULSE TRANSMITTER SPECTRUM . 
 MINES RADIOWAVE PROPAGATION -ODELS SUCH AS 6/!#!0 AND !3!03 GENERATE  PREDICTIONS OF POINT 
 WAY ATTENUATION IN THE OXYGEN ABSORPTION LINE AT  '(Z IS ABOUT  D" PER KM  WHICH ESSENTIALLY PRECLUDES ITS APPLICATION !TTENUATION IN RAIN CAN ALSO BE A LIMITATION IN THE MILLIMETER WAVE REGION )NTEREST IN MILLIMETER RADAR HAS BEEN MAINLY BECAUSE OF ITS CHALLENGES AS A FRONTIER  TO BE EXPLORED AND PUT TO PRODUCTIVE USE )TS GOOD FEATURES ARE THAT IT IS A GREAT PLACE FOR EMPLOYING WIDE BANDWIDTH SIGNALS THERE IS PLENTY OF SPECTRUM SPACE  RADARS CAN HAVE HIGH RANGE 
 202. Sensors 2019 ,19, 516 FR retrieval has been well studied in the last two decades [ 14–21]. In this paper we chose the B&B method [ 16] as the FR estimator due to its robustness and reliability: /bracketleftBigg Z11 Z12 Z21 Z22/bracketrightBigg =/bracketleftBigg 1 j j1/bracketrightBigg/bracketleftBigg Mhh Mvh Mvh Mvv/bracketrightBigg/bracketleftBigg 1 j j1/bracketrightBigg Ω=1 4arg/parenleftbig/angbracketleftbig Z12Z∗ 21/angbracketrightbig/parenrightbig .(2) In Equation (2), the M matrix represents the measured full polarimetric scattering matrix. 
  
 -ARCONI 5+ 2,- 53! 
 3.5.3. 13. W. 
 In the same 3 seconds, the 600 rpm antenna scans by the  target JO times, receiving two pulses on each scan. A scan-to-scan integration improvement  can be achieved with the high-speed antenna if the storage properties of the CRT screen permit  efficient integration (as with a storage tube) or if some form of automatic integration is used.  Experimental measurements using civil-marine radar with a 1 ° beam width and 5000 Hz  pulse repetition frequency show that increasing the antenna rotation rate from 20 to  420 rpm improves the target-to-clutter ratio from about 4 to 8 dB depending on the sea  state. 
 In order to achieve the most  efficient combining of parallel amplifier stages, the phase and amplitude balance  of individual stages should be as similar as possible. Any deviations from identical  phase and amplitude balance result in power output lost to the resistive terminating  port of the combiner. The power lost to similarity differences, from either phase or  amplitude, is dictated by vector addition and is given by:  PLOST = 20*log ((SQRT (P12 + P22 + 2*P1*P2*COS(q)))/(P1 + P2))  (11.4) where q  is the phase difference in degrees between two amplifiers that are summed  together, SQRT indicates the “square root of,”, and P1 and P2 are the power levels of  each amplifier in watts. 
 ££°£È  2!$!2 (!.$"//+  FROM HIGH BUS VOLTAGES n VOLTS   WHILE MAINTAINING TRANSISTOR 
 HOP ZONE !S SHOWN IN &IGURE   A MULTIPLICITY OF HOPS MAY EXIST  AND ENERGY MAY EVEN  CIRCLE THE EARTH CLUTTER ECHOES FROM THESE LONG RANGES CAN SERIOUSLY DEGRADE RADAR PERFORMANCE ! COMPARISON OF &IGURES  A  B  AND  C REVEALS THAT DIFFERENT  RANGE EXTENTS ARE ILLUMINATED BY USING DIFFERENT OPERATING FREQUENCIES  WITH LONGER STARTING RANGES REQUIRING HIGHER FREQUENCIES )N THE EXAMPLES SHOWN   -(Z ILLUMI 
 1261–1268, 1969. 65. R. 
 C.: Microwave Lenses, Symposiirm on Microwave Optics, McGill University, Montreal,  AFCRC-TR-59-1 IU(I), ASTIA Document 211499. pp. 8-17, April, 1959. 
 2. Hcan. R. 
 COMPLIANT RADARS HAVE HAD THE CAPABILITY TO EMPLOY USER 
 Whenthetargetliesinthenulls,noechosignalisreceived. Theangle(inradians) ofthefirst(lowest) lobeisapproximately equalto,l./4h".Iflow­ anglecoverage isdesired,theradarantenna heightshouldbehighandthewavelength ofthe radiated energysmall.Theantenna patternlobescausedbythepresence ofthegroundmight sometimes beofadvantage whenthelongestpossible detection rangeisdesiredagainstlow­ altitudetargetsandwherecontinuous coverage isnotrequired. Thesimpleformoftheradarequation [Eq.(1.9)]maybewrittenwiththepropagation factor'l included toillustrate theeffectoftheplaneearth: forsmallangles J(12.8) Thereceived signalpowerfortargetsatlowangles(onthelowersideofthefirstlobe)variesas theeighthpoweroftherangeinsteadofthemoreusualfourthpower.Thisphenomenon has beenexperimentally verifiedforshiptargetsatshortrangeswheretheplane-earth approxima­ tionhassomevalidity.! Another difference between Eq.(12.8)andthenormalradarequation isthefactorG/,l.,whichappears inplaceofthefactorGk Theanalysis inthissectionisbasedonmanysimplifying assumptions; therefore care shouldbeexercised inadapting theresultsandconclusions tomorerealisticsituations. 
 However, wecan roughly distinguish different orders ofwhat was called above theapriori probability ofthe signal. Compare, forexample, theuse ofaradar set forearly warning (detection ofenemy aircraft atagreat distance) and forground control ofaircraft, inwhich aselected plane, already picked upontheradar, isfollowed, itsposition being noted ineach scan. Inthe latter case, weknow about where tolook forthe echo inagiven scan, having observed theposition intheprevious scan and knowing approxi- mately the course and speed from still earlier information. 
 Ayers, J. M. Ralston, R. 
 Van Nostrand Reinhold Co., New York, 1969.  128. Kelleher, K. 
 Freedman, N.: Bistatic Radar System Configuration and Evaluation, Raytheon Com- pany, Independ. Dev. Proj. 
 METEOROLOGICAL RADAR  19.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 If we multiply the numerator and denominator by sv, Eq. 19.44 becomes  var()v T Tv vv f= =λσ π σσ π σ2 02 0 8 4 (19.45) Thus, it is seen that the variance of the mean velocity estimate ˆv is directly propor - tional to the variance of the doppler spectrum and inversely proportional to the number  of independent samples, sf T0. Note also that var (ˆ)vis proportional to l, indicating  that, for the same processing time T0 and for the same sv, the variance of the estimate  can be reduced by reducing the wavelength, which increases the number of indepen - dent samples. 
 The strength of the  reflected wave is determined  by the reflection coefficient,  a value that depends upon the  frequency and polarization  of radiation, the angle of  incidence, and the roughness  of the reflecting surface. For shallow incidence  angles and smooth seas, typi - cal values of the reflection coefficient are near unity (i.e., the reflected wave is almost  as strong as the incidence wave). As the wind speed increases, the ocean surface grows  rougher and the reflection coefficient decreases. 
 Conr. Record, vol. 7, pt. 
 11.136 is obtained with a periodic train of pulses. The internal  structure of each of the major components, illustrated figuratively by the simple arrows,  depends on the waveform of the individual pulses. The thumbtack ambiguity diagram,  Fig. 
 The unambiguous doppler interval corresponding  to fdT = 1 is 28.4 m/s for the parameters used to calculate this response. Figure 2.48 shows the time-domain responses for this filter as the antenna scans  past a point of clutter, such as a water tower. This figure shows the input to the elliptic  filter and the residue output. 
 85-I02.January, 1978. 95.Howard. D.D.:Predicting Target-Caused ErrorsinRadarMeasurements, Electronic WarfareDefense Elecrrortio. 
 10, no. 2, pp. 83–222. 
 Electrons originate fromthecylindrical cathode whichiscoaxialtotheRFslow-wave circuitthatactsastheanode.Thecathode inacrossed-field tubeisalsoknownasthe.'loll!. (Thetermsole.whichmeanswound{'Iatl!.comesfromtheFrench. whodidmuchoftheearly workoncrossed-field devices.) [nsomecrossed-field devicesthesoledoesnotemitelectrons. 
 Sens. , vol. 27, pp. 
  
 K. Fung and G. W. 
 OUT 
 Pollard was proving that radar range-  finding was more accurate in dealing with aircraft than  were the big optical range-finders. C. E. 
 Thus, the scattering matrix is a quantitative description of the transfor - mation of polarization state upon reflection, as well as the magnitude and phase of  each reflection coefficient. It is often true that the field polarizations are not changed  during propagation, the irrotational assumption. In this case, the polarizations of the  backscattered waves are equivalent to those that arrive at the radar. 
 1-oridori. pp. 352 359, IEEE Corifcrericc Publication no. 
 8.)FIG. 4.5 Inverted coaxial magnetron. (a) Simplified cross section. 
 In practice, TV' values in the range of 3 to 5 are normally chosen. The missile does not respond instantaneously to an LOS rate; rather, a finite response time, made up of several components, governs the process. This equiv- alent time constant, referred to as the guidance time constant T^, is a key param- eter affecting miss distance. 
 IRE, vol. 21, pp. 427-463, 1933. 
 Orie pulse is transmitted on the forward antenna, and the  other pulse is transmitted on the rear antenna so that the two pulses from the two different  antennas are transmitted and received at the same point in space. The result is as if the  radar antenna were stationary. The distance traveled between pulses is generally less than  the antenna dimension so that the two antenna beams might be generated with two  overlapping reflector antennas or with a phased array divided into two overlapping  subarrays.64 The effective separ~tion between the antennas, T pvx, varies with the angle  00 as well as the aircraft velocity v. 
 Federal Communications Commission, http://www.fcc.gov/aboutus.html. ch21.indd   41 12/17/07   2:51:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Any use is subject to the Terms of Use as given at the website. The Radar Transmitter.  THE RADAR TRANSMITTER  10.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 high-power klystron tube used in the original Ballistic Missile Early Warning System  had a demonstrated life in excess of 50,000 hours. Symons6 reports that one of the  BMEWS tubes that he designed was still operating after 240,000 hours when the  radar in Greenland was replaced by the solid-state Pave Paws radar. 
 Since in the set of 16 samples, the test sample has equal probability of being the smallest sample (or equivalently any other rank), the probability that the test sample takes on values O, 1,..., 15 is 1:16. A simple rank detector is constructed by comparing the rank with a threshold K and generating a 1 if the rank is larger, a O otherwise. The Os and Is are summed in a moving window. 
 Chicago. 1973 .  .'2. 
 39. Soviets Plan to Launch New Spacecraft, Aviat. Week Space Technol., vol. 
 Several types of ferrite phase  shifters have been developed, but those that have been of interest in applications are the  Reggia-Speficer, toroidal latching, flux drive, and dual-mode phase shifters.  Reggia-Spencer phase shifter. This was one of the first ferrite phase shifters to be applied  successfully to radar. 
 3. C. E. 
 § ©¨¶ ¸· .XI    WHERE  }M £ .XI   &)'52%  2ATIO DETECTOR FROM ' 6 4RUNK  &)'52%  #URVES OF PROBABILITY OF DETECTION VERSUS SIGNAL 
 ”Again, letsome passive circuit, which weshall call C,be inthermal equilibrium atthetemperature T.Ifnowwe connect across the terminals ofCanimpedance element Z,itself atabsolute zero, the maximum rate oftransfer ofenergy from CtoZwithin the frequency band (Bisjust lcT(B. This rate, which isactually attained when Zis adjusted tobethecomplex conjugate oftheimpedance observed between theterminals ofC,wecall the “availablen oisepower” from C. IfZis not atabsolute zero, thetransfer isnot wholly one-sided; and ifZisat thesame temperature asC,thenettransfer vanishes, asofcourse itmust. 
 SPEED DIGITAL COUNTER DRIVEN BY A STABLE OSCILLATOR 4HE COUNTER IS RESET TO ZERO AT THE TIME OF THE TRANSMIT PULSE 4ARGET RANGE IS REPRESENTED BY A NUMBER STORED IN A DIGITAL REGISTER  AS SHOWN IN &IGURE  ! COINCIDENCE CIRCUIT SENSES WHEN THE DIGITAL COUNTER REACHES THE NUMBER IN THE RANGE REGISTER AND GENERATES THE RANGE GATE  AS INDICATED IN THE BLOCK DIA 
 S. Gilmour, Jr., Principles of Traveling Wave Tubes , Boston, MA: Artech House, 1994,   Sec. 18.4. 
 02& ADVANTAGE OF A SINGLE BLIND 
 ANGLE MICROWAVE LENS    %ACH PORT CORRESPONDS TO A SEPARATE BEAM 4HE LENS PROVIDES APPROPRIATE  TIME DELAYS TO THE APERTURE  GIVING FREQUENCY 
 Expressions for  *  The one-oval area formula is derived from  Eq. (D.7a) in Willis.1 It is also used for calculating the lemniscate area.  Formulas for the two-oval area are derived from Eq. 
 A flat dish with a long focal length minimizes the distortions. Progressively illuminating a smaller fraction of the reflector as the feed is displaced accomplishes the same purpose. Two secondary effects are influential in the design of extended feeds. 
 An improvement of the  angle resolution of better than .02° is easily possible.  For monopulse Radar in two plans ( θ  and ψ) the circuits of both single planes ar e merged over a further hybrid, shown in Figure  13.7. Radar System Engineering  Chapter 12 – Selected Radar Applications  140     beam 2 ψ beam 1 θ sum Σ ψdiff. 
  SIN PI SIN PS COS E    4RENDS IN THIS BISTATIC SCATTERING COEFFICIENT DATABASE ARE SUMMARIZED FROM 7ILLIS   7EINER  AND #HAPTER  IN 7ILLIS AND 'RIFFITHS AS FOLLOWS L -OST OF THE  R" DATABASE IS AT 8 BAND  WITH  OUT OF  DATA CURVES FOR BOTH TERRAIN  AND SEA CLUTTER TAKEN BY  OF THE  ORGANIZATIONS 4HE REMAINING DATABASE CONSISTS   OF  DATA CURVES AT , BAND TERRAIN ONLY    AT 3 BAND TERRAIN ONLY    AT # BAND SEA ONLY   AND  AT  + A BAND TERRAIN ONLY   EACH PROVIDED BY ONE ORGANIZATION .O DATA  IS AVAILABLE AT 6(& OR 5(& 4HUS ONLY 8 BAND ALLOWS CHOICES IN SELECTING DATA 4HE #OST0EAKE   AND $OMVILLEn IN 
 UP IS ALSO PROVIDED  AS THIS ELIMINATES SMALL OSCILLATIONS IN THE RADAR IMAGE DUE TO THE SHIPS YAW THAT OCCUR WHEN THE DISPLAY IS SET TO (EAD 
 [CrossRef ] 53. Benattou, M.M.; Balz, T.; Liao, M. Measuring surface subsidence in Wuhan, China with sentinel-1 data using psinsar. 
 Howell, “Limited scan antennas,” presented at IEEE AP-5 Int. Symp., 1972. 29. 
 166 INTRODUCTION TO RADAR SYSTEMS  target makes an angle Oto the perpendicular bisector of the line joining the two antennas. The  distance from antenna l to the target is  R 1 = R + ~ sin ()  and the distance from antenna 2 to the target is  R2 = R -~ sin 0  The phase difference between the echo signals in the two antennas is approximately  6.<j) = \n d sin 0 .. ( 5.1)  For small angles where sin O:::::: 0, the phase difference is a linear function of the angular error  and may be used to position the antenna via a servo-control loop. 
 ELEMENT GEOMETRY AND PHASING &)'52%  0ROJECTION OF POINTS ON A HEMISPHERE ONTO THE PLANE  OF THE ARRAY .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°£Ç IS DEFINED AS  REAL SPACE  THE HEMISPHERE INTO WHICH ENERGY IS RADIATED 4HE INFINITE  REGION OUTSIDE THE UNIT CIRCLE IS REFERRED TO AS  IMAGINARY SPACE !LTHOUGH NO POWER IS  RADIATED INTO IMAGINARY SPACE  THE CONCEPT IS USEFUL FOR OBSERVING THE MOTION OF GRAT 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 But there are disadvantages. First, emission controls are almost invariably a seri - ous matter when it comes to obtaining a license to radiate. 
 NITION )  PROVIDED IN THE ND EDITION OF THIS  2ADAR (ANDBOOK USED THE NOISE GAIN OF  THE DOPPLER -4)  FILTER AS THE NORMALIZING FACTOR 4HE INCREASED USE OF PULSE DOPPLER  FILTER BANKS IN MODERN RADAR HAS  HOWEVER  LED TO A USE OF THE )%%% DEFINITION WHERE  THE AVERAGING OF THE SIGNAL 
 41. S. Werness, W. 
 Relative Importance of Theory and Empiricism.  The theory of radar ground  return has been the subject of many publications.4,5 The various theories, insofar as  they can be confirmed by experiment, provide bases for judging the effects of varia - tions in the dielectric properties of the ground, of the roughness of the ground and  nature of vegetative or snow cover, of radar wavelength, and of angle of incidence.  Viewed as aids to insight, radar ground-return theories can be extremely useful. 
 On-Board Processors. The bandwidth requirements for the satellite communi- cations data link can be reduced when an on-board processor is utilized. The major functions of an on-board processor in a large SBR can include pulse compression, doppler filtering, adaptive beamforming, calibration, range walk correction, video integration, constant false-alarm rate (CFAR), monopulse error signal, burst waveform weighting, sidelobe blanking, and editing out interference. 
 LIMITED DETECTION ARE AVOIDED )N THE FOLLOWING PARAGRAPHS  TWO DIFFERENT APPROACHES TO PERFORMANCE MODELING FOR THE CASE OF NOISE 
 TIALLY INDEPENDENT OF THE ACTUAL BEAM SHAPE OR APERTURE ILLUMINATION FUNCTION USED 4HE CLUTTER SPECTRAL SPREAD DUE TO SCANNING  NORMALIZED TO THE 02&  IS   SF4N      WHERE 4   02& IS THE INTERPULSE PERIOD 4HE  COMBINED SPECTRAL EFFECTS OF INTERNAL CLUTTER MOTION AND ANTENNA SCANNING MODU 
 Shown are the horizontal . DISTANCE WEST OF CP-2 (km) UG. 23.7 Vector wind fields in a horizontal plane derived from dual-doppler radar observations of a summertime con- vective storm near Denver, Colorado. 
 J. Palermo, and L. J. 
 662, Aug. 4,1945; Reu:Sci.InSt.17,490(1946).. SEC.17.14] MZCROWA VESYSTEM FORPOINT-TO-POINT SERVICE 725 inthefrequency-control circuits sothat they willnotstabilize against the signal frequencies. 
 DELAY $0#! MECHANIZATION        
 MANCE 3OME APPROPRIATE DESIGN CONSIDERATIONS ARE u !N ANALOG 
 !  *UNE    % . "RAMLEY AND 3 - #HERRY  h)NVESTIGATION OF MICROWAVE SCATTERING BY TALL BUILDINGS v  0ROC  )%%  VOL   PP n  !UGUST   ! % "RINDLY ET AL  h! *OINT !RMY!IR &ORCE INVESTIGATION OF REFLECTION COEFFICIENT AT  # AND +U  BANDS FOR VERTICAL  HORIZONTAL AND CIRCULAR SYSTEM POLARIZATIONS v ))4 2ESEARCH )NSTITUTE  &INAL  2EPT  42 
 Lindner, J.: Binary Sequences Up to Length 40 with Best Possible Autocorrelation Function, Electron. Lett., vol. 11, p. 
 3CANNED !NTENNA )NVERSE #ASSEGRAIN   !N ANTENNA TECHNIQUE THAT  USES A MOVABLE 2& MIRROR FOR SCANNING THE BEAM  CALLED A  MIRROR 
 199–208,  January 1978. 20. P. 
 BUTE THE AMPLITUDE AND PHASE DIFFERENCES MEASURED ACROSS THE CHANNELS ONLY TO THE NATURE POWER AND $O!  OF THE IMPINGING INTERFERENCE 4HERE ARE SEVERAL SOURCES OF MISMATCHING THE IMPERFECT MATCHING OF THE ANALOGUE RECEIVING CHANNELS IS ONE OF THE MAIN LIMITATIONS TO THE INTERFERENCE CANCELLATION 4HE EFFECT OF THIS MISMATCH ON THE *#2 HAS BEEN STUDIED IN THE LITERATURE SEE &ARINA  AND REFERENCES THEREIN &OR CONTEMPORARY PRESENCE OF AMPLITUDE AND PHASE MISMATCHES  THE *#2 HAS AN  EXPRESSION THAT IS DERIVED IN !PPENDIX  ! NUMERICAL APPLICATION OF THIS EQUATION IS  SHOWN IN &IGURE  THE PARAMETER VALUES OF THE STUDY CASE ARE QUOTED IN &ARINA  &IGURE  SHOWS THE *#2 CONTOUR CURVES VERSUS THE NORMALIZED AMPLITUDE  AN AND THE  PHASE B DEGREES  MISMATCHES OF THE ANALOGUE RECEIVING CHANNELS SEE &ARINA FOR THE  PRECISE DEFINITION OF THESE PARAMETERS   )T IS SEEN THAT TO HAVE  D" OF  *#2  ONE NEEDS TO SPECIFY TIGHT REQUIREMENTS FOR  BOTH AMPLITUDE BELOW   AND PHASE BELOW   MISMATCHES 4HIS FIGURE MOTIVATES THE NEED TO RESORT TO EQUALIZATION DIGITAL FILTERS TO COMPENSATE FOR THE MISMATCHES OF THE AUXILIARY CHANNELS IN THEIR ANALOGUE PART  WITH RESPECT TO THE MAIN CHANNEL 4HIS SUBJECT IS COVERED IN &ARINA  AND REFERENCES THEREIN %XAMPLES OF OTHER POSSIBLE LIMI 
 The conversion efficiency of  a CF J\ is defined as  Erfi . RF power output -RF drive power 1c1ency = . d-c power input (6. 
 TER IN THE FILTER STOPBAND 4HE CLUTTER PHASE VARIES FROM RANGE CELL TO RANGE CELL OWING TO THE DISTRIBUTION OF THE LOCATION OF THE SCATTERERS IN AZIMUTH (ENCE  IT IS NECESSARY TO AVERAGE THE RETURN FOR AS LONG AN INTERVAL AS POSSIBLE 4!##!2 IS USED TO DESCRIBE THE CENTERING OF THE RETURNED CLUTTER SPECTRUM TO THE ZERO FILTER FREQUENCY 3INCE THE TECHNIQUE COMPENSATES FOR DRIFT IN THE VARIOUS SYSTEM ELEMENTS AND BIASES IN THE MEAN DOPPLER FREQUENCY DUE TO OCEAN CURRENTS  CHAFF  OR WEATHER CLUTTER  IT IS USED IN SHIP 
 ENTRY VEHICLES 26S  AT LONG RANGES REQUIRES THAT ACTIVE ARRAY RADARS HAVE A LARGE POWER 
 ING CONFIDENCE 4HIS HAS NOT ALWAYS BEEN SO  LEAVING OUR GENERAL KNOWLEDGE ABOUT SEA CLUTTER TO BE SUMMARIZED ROUGHLY AS FOLLOWS &OR THE HIGHER  OF WIND SPEEDS ENCOUNTERED OVER THE WORLDS OCEANS GREATER THAN ABOUT  KT   MICROWAVE SEA CLUT 
 Gray. C. L.: Estimating the Effect of Feed Support Member Blocking on Antenna Gain and Side  Lobe Level, hficrobr.c~ve J., vol. 
 FIO. 5.3.—Approximate frequencysible forms ofmodulation might wellspectrum ofasequence ofpulses ofcarrier occupy abook, but sufficient infor- frequency f~,repetition irequency f,,and duration r.mation forpresent purposes iscon- tained inthebrief series ofstatements that follow. Inthe amplitude-modulation case the signal generally consists ofa carrier ofangular frequency uO,which ismodulated atafrequency asso- ciated with the repetition rate. 
 Most models have a statistical description of F2 maximum electron density (or critical frequency) in the form of a median and upper and lower decile values. Goodman and Reilly discuss shortwave prediction methodologies on pages 230 to 237 of Ref. 11. 
   NO   PP n  3EPTEMBER   $ 2 ! -C-AHON AND 2 & "ARRETT  h!N EFFICIENT METHOD FOR THE ESTIMATION OF THE FREQUENCY OF  A SINGLE TONE IN NOISE FROM THE PHASES OF DISCRETE &OURIER TRANSFORMS v  3IGNAL 0ROCESSING  VOL    PP n    * 7 4AYLOR  h2ECEIVERS v #HAP  IN  2ADAR (ANDBOOK  ND %D  - ) 3KOLNIK ED   .EW 9ORK  -C'RAW 
 AMPLITUDE APPROXIMATIONS IN THE FORM OF %Q  THAT MAKE LITTLE SENSE FOR MICROWAVE SCATTERING FROM REAL SEA SURFACES  OR OPTICAL LIMITS SUCH AS %Q  THAT RELATE TO THE PROBABILITY DENSITIES OF SPECULARLY REFLECTING SURFACE SLOPES )T APPEARS  THEREFORE  THAT THE USE OF INTEGRAL FORMULATIONS IN THE PRACTICAL SOLUTION OF THE SEA CLUTTER PROBLEM AT MICROWAVE FREQUENCIES WILL REQUIRE SOMETHING MORE #OMPOSITE 
 Therefore, the conventional unit of Z is in mm6/m3. For ice particles, D1 is given by the diameter of the water droplet that would result if the ice particle were to melt completely. It is often convenient to treat the drop or particle size distribution as a con- tinuous function with a number density N(D), where N(D) is the number of drops per unit volume, with diameters between D and D + dD. 
 The fundamental accu- racy performance of a phase comparison monopulse system is identical to that of an amplitude comparison monopulse system converted by this method, and vice versa. Therefore, the fundamental accuracy performance is addressed here from the conceptual viewpoint of amplitude comparison monopulse. There are a variety of ways to implement monopulse processing on a sum- difference beam pair, depicted functionally in Fig. 
 J.  O’Connor, W. B. 
 POWER MAGNETRONS ,IMITATIONS OF -AGNETRONS  7HEN THE MAGNETRON WAS FIRST INTRODUCED  IT PRO 
 Theproduction supervisor wasGayleAngelson. LibraryofCongress Cataloging InPublication Data Skolnik,MerrillIvan,date Introduction toradarsystems. Includesbibliographical references andindex. 
 Microwave radars  have used FM-CW waveforms in the past, but in most cases, these have been replaced by  waveforms that don’t require separate transmitter and receiver sites. Table 20.1 presents a comparison of some key radar parameters for representative  radar systems of each type, and contrasts the ways in which the respective modes of  propagation, scattering, noise, and deployment constrain the form and function of  radar systems. Implications for Skywave Radar Design . 
 ch18.indd   9 12/19/07   5:13:58 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 transmitted   pulse   echo   pulse  transmit time or   Pulse Width τ  receiving time  rest  time  Pulse Repetition Time (PRT) or   Pulse Repetition Period (PRP)  . Radartutorial (www.radartutorial.eu)   6 Ranging   The distance of the aim is determined from the running time of the high -frequency transmitted signal  and the propagation c0. The actual range of a target from the radar is known as slant range. 
 For the repetition period Τ follows the unambiguous range of coverage:   € unamR=c0⋅T 2=c0 2PRF (4.3)  The resolution, meaning the distance separation of two targets, is in all case inversely proportiona l  to the bandwidth B, which will be employed. As a good approximation the following can be applied:   BcR2min> Δ  (4.4)  In the last few years several Super-Resolution Algorithms , as ESPRIT, have been developed, with  which the resolution under cer tain conditions can be considerably improved.  . 
 JK2    WHERE   %RVR HR% % § ©¨¶ ¸·  AND %TVT HT% % § ©¨¶ ¸·  AND   333 33 § ©¨¶ ¸·VV VH HV HH    )N THE USUAL RECIPROCAL MEDIA   3VH   3HV 3INCE THE CHOICE OF A PHASE REFERENCE IS  ARBITRARY  THERE ARE THEN THREE INDEPENDENT MAGNITUDES \3VV\  \3HH\  \3HV\   BUT ONLY TWO  INDEPENDENT PHASES 3HH   3HV  4HESE QUANTITIES CAN BE USED TO DESCRIBE THE PROPER 
 (3) Record the obtained index λtto the support set and its corresponding vector in A/prime ito the incremental matrix: Λt=Λt∪{λt}; Φi,t=[Φi,t−1Ai,λt/prime](21) (4) Adopt the least square method to calculate the projection coefﬁcient of each channel: gi,t=arg min gi/bardbls/prime i−Φi,tgi/bardbl(i=1, 2) (22) (5) Update residual signal ri,t: ri,t=si/prime−Φi,tgi,t(i=1, 2) (23) (6) For the number of iteration t=t+1, repeat step (2) to (4) until the energy of the residual signal is lower than the preset threshold Thres or the number of iterations reaches the preset sparsity K. Compared with the standard OMP algorithm, the proposed algorithm is mainly improved in step (2). In the standard OMP algorithm, the support set for different channels may be different, because the index λt,iis determined only for the single-channel signal itself: λt,l=arg max k∈{1,···,PQ}/angbracketleftBig ri,t−1∗,Ai,k/angbracketrightBig (i=1, 2). 
 D.C., May 29. 1974.  33. 
 Any use is subject to the Terms of Use as given at the website. Meteorological Radar.  METEOROLOGICAL RADAR  19.456x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19  95. A. 
 TO 
 and pulse compression,  433  Fresnel region, antenna, 229  Fresnel zone plate, 523, 527  Gain. antenna, 224-226  Gaseous discharge phase shifter, 297  Gaussian probability density function, 22  Geodesic dome, 265  Glint. 168-172  Grating lobes, 281, 283, 300, 332  Grazing angle, 473  Grid-controlled tubes, 213  Ground-wave 0TH radar, 536  Half-wave wall radome, 267  Hard-tube modulator, 215-216  Height finder radar, 541-546  Helical scan, 177, 545  Hemispherical coverage arrays, 328-329  HF 0TH radar, 529-536  High-range-resolution monopulse, 181-182,  High-range-resolution radar, 434-435  Hologram, 523-526  Home on jam, 549  Huggins phase shifter, 303-305  Hybrid-coupled phase shifter, 289  IAGC, 488  Ice:  on antennas, 240  on radomes, 269  sea, 481-482  Ice spheres, scattering from, 502  Ideal observer, 380  IF cancellation, MTI, 126  Image frequency, of mixer, 347  Image-recovery mixer, 349  Improvement factor, MTI:  antenna scanning, 134-136  antenna sidelobes, 145  clutter nuctuations, 131-134  defined, 111, 129  equipment instability, 130-131  limiting, 136-138  quantization, 120 . 
 58. F. E. 
 OFFS BETWEEN PERFORMANCE OF A VARIETY OF PARAMETERS 3WITCHED ATTENUATORS GENERALLY PROVIDE MAXIMUM ATTENUATION ACCURACY  FASTER SWITCHING SPEED  IMPROVED AMPLITUDE AND PHASE STABILITY  GREATER BANDWIDTH  HIGHER DYNAMIC RANGE  AND HIGHER POWER HAN 
 Figure 11.25 shows acoaxial-type mixer which iswidely used forthe 9-to 1l-cm band. Itbolts directly ontheTR-tube cavity and theoutput FIG. 11.25.—Coaxial-type mixer; 10.cm band. 
 TION IN THE RANGE DIMENSION 4HE 34!0 METHODS USED IN /4( RADAR ARE VERY SIMILAR CONCEPTUALLY TO THOSE ADOPTED FOR AIRBORNE RADAR  ESPECIALLY THE FORMER TAP ARCHITEC 
  
 16.3. The Degenerative Trigger Circuit.—A highly stable oscillator generates thetransmitter trigger, and acorrection isapplied tothe oscillator ifit fails tomatch the delay line. This correction isobtained asfollows, Several microseconds before thetransmitted pulse, theecho input tothe 1Nonblocking amplifier design isdiscussed inSees. 
 TIVE APERTURE OF  M BY  M FOLLOWING DEPLOYMENT )N STRIP 
 SCAN RATIO THE EXPERI 
 PULSE MATCHED FILTER $IGITAL 3IGNAL 0ROCESSING  &OLLOWING DIGITAL PREPROCESSING IS A DOPPLER FIL 
 Jason-1 followed in the footsteps of TOPEX, figuratively and literally.  After the launch of Jason-1 into the T/P orbit, TOPEX was maneuvered into a “tan - dem” phasing so that the measurements of the two altimeters could be cross-calibrated.  Jason-2 is essentially identical to Jason-1. 
 If r is the pulse width, Tp the pulse repetition  period, and/P = 1/TP is the pulse repetition frequency, then the number of decisions n1 in time  Tra is equal to the number of range intervals per pulse period r, = Tp/r = 1/fp r times the  number of pulse periods per second/p, times the false-alarm time Tra. Therefore, the number of  possible decisions is n1 = Trafptf = Tra/r. Since r:::: 1/B, where Bis the bandwidth, the false­ alarm number is n 1 = Tra B = 1/ Pra. 
 Crichlow, W. Q., D. F. 
 Wexler, “A determination of kinematic properties of a wind field using  doppler radar,” J. Appl. Meteorol ., vol. 
 If it is defined that the impulse response of the impulse function δ(t) equals h(t), then one can  obtain the response of any function x(t) if one divides the function into durations of ∆ τ, as  shown in Figure 8.22.  f (t) f (t)f (τ) Δτ τt1 t2 t   Figure 8.22  Division of the pulse function.   The impulse function δ(t) with the duration ∆ τ has the amplitude x(t). 
 and L. M. Spetner: Polarization and Depression-Angle Dependence of Radar Terrain  R~turn. 
 Howard, “Radar target angular scintillation in tracking and guidance systems based on  echo signal phase front distortion,” in Proc. Nat. Electron. 
 It will be recalled that  most of the analysis of the radar equation in Chap. 2 was based on the envelope detector.  The envelope detector consists of a rectifying element and a low-pass filter to pass the  modulation frequencies but to remove the carrier frequency. 
 A. C. Best, Physics in Meteorology , London: Sir Isaac Pitman & Sons, Ltd., 1957. 
 The phase difference  between the two signals (or the differetlcc in travel time) depends on from which slot they  originated. whicli in turn depends on the elevation angle of arrival. Thus a measurement of  pltase difTerence restilts it1 a nieasurement of elevation angle. 
 References 1. Ginzburg, V .L.; Zheleznyakov, V .V .; Zaitsev, V .V . Coherent Mechanisms of Radio Emission and Magnetic Models of Pulsars ; Provided by the NASA Astrophysics Data System; Kluwer Academic Publisher: Dordrecht, The Netherlands, 1969; pp. 
 TO 
 Conclusions Scattering anisotropy analysis is important and useful in the ﬁeld of SAR. Previous studies have mostly used polarimetric SAR data. In this paper, we use the CSAR data to analyze anisotropic scattering behavior across the azimuth. 
 no. 21. pp. 
 OUSLY WRONG 4HIS OCCURS FOR FLAT AND SINGLY CURVED SURFACES 0HYSICAL /PTICS  4HE THEORY OF PHYSICAL OPTICS 0/  IS A SUITABLE ALTERNATIVE  FOR BODIES WITH FLAT AND SINGLY CURVED SURFACE FEATURES 4HE THEORY IS BASED ON TWO APPROXIMATIONS IN THE APPLICATION OF %QS  AND   BOTH OF WHICH ARE REASONABLY EFFECTIVE IN A HOST OF PRACTICAL CASES 4HE FIRST IS THE  FAR 
 Brown. R. K.. 
 [ CrossRef ] 11. Eldhuset, K. Ultra high resolution spaceborne SAR processing. 
 MOVING NATURE  OF THE TARGETS OF INTEREST  AVERAGING THE RADAR IMAGE OVER MANY ANTENNA SCANS USING AN OPTIMIZED INFINITE IMPULSE RESPONSE ))2  FILTER CAN GIVE A  VERY DETAILED IMAGE THAT  ALLOWS THE USER TO DIFFERENTIATE BETWEEN ICE AND WATER AREAS )N PARTICULAR  SMALL ICE FEATURES SUCH AS BERGY BITS  ICEBERGS WITH DIMENSIONS ABOVE THE  WATERLINE OF LESS THAN   METERS IN BREADTH AND GREATER THAN  METER IN HEIGHT  AND GROWLERS LESS THAN  METERS IN BREADTH AND LESS THAN  METER SHOWING ABOVE THE WATER LINE  ARE READILY DETECTED BY SUCH SYSTEMS )NTEGRATION OVER  SECONDS HAS BEEN FOUND TO BE SUITABLE  WITH THE ANTENNA ROTATING AT  RPM 4HE INCREASED CAPABILITY OF ICE  TARGET DETECTION IN SEA CLUTTER WITH HIGHER ANTENNA ROTATION RATES HAS ALSO BEEN DEMONSTRATED $RAMATIC IMAGES OF ICE HAZARDS CAN BE PRODUCED BY SUCH RADARS  SUCH AS THAT ILLUSTRATED IN &IGURE .   #)6), -!2).% 2!$!2   ÓÓ°£x &)'52%  )CE FEATURE DETECTION USING ))2 FILTERING ON 2UTTER 3IGMA  RADAR PROCESSOR  #OURTESY OF 4RANSPORT #ANADA  . ÓÓ°£È  2!$!2 (!.$"//+  3OLID 
 2002 ,38, 723–733. [ CrossRef ] 84. Sensors 2019 ,19, 1920 3. 
 Losses in the output circulator, final power combining, and the  fault detection circuitry reduced the combined power level to 2500 W. Output modules  were liquid-cooled for normal operation, but an emergency backup forced-air cooling  was provided in the event of a primary-cooling-system failure. The dissipated heat  could be tolerated because the system operated at a low duty cycle. 
 The second term describes the disturbing pattern and represents a source of  sidelobe energy whicli depends on the mean-square phase error and the square of the correla-  tion interval. For small phase errors, when only the first term of the series (n = 1) need be  considered. Eq. 
 The role of the operator in the ECCM chain pertains to the more general topic of  human-factor  ECCM.29 This is a generic ECCM technique that covers the ability of  an air defense officer, a radar operator, a commanding officer, and/or any other air  defense associated personnel to recognize the various kinds of ECM, to analyze the  effect of the ECM, to decide what the appropriate ECCM should be, and/or to take  the necessary ECCM action within the framework of the person’s command structure.  However, the human operator is less effective against a simultaneous attack of many  enemy vehicles supported by a strong ECM force. An operator confronted with a large  mix of ECM types and a large number of ECCM techniques is likely to do the wrong  thing and/or react too slowly. 
 A change inwavelength iseven more difficult todiscuss asitentails changes inS~i., P,and possibly uaswell. 2.5. Beams ofSpecial Shapes.—In several applications ofradar, use ismade ofanantenna designed tospread theradiated energy out over a considerable range inangle inone plane. 
 In general, there are advantages that silicon FETs exhibit, namely,8 1. Thermal stability: This results from a negative temperature coefficient of power gain. 2. 
 vi CONTENTS  3.4 Airborne Ooppkr Navigation l) ::>  3.5 Multiple-Frequency CW Radar 95  Rderenccs l)K  4 MTI and Pulse Doppler Radar 101  4.1 I nl rod uction IOI  4.2 Delay-Line Cancelers 106  4.3 Multiple, or Staggered, Pulse Repetition Frequencies 114  4.4 Range-Gated Doppler Filters 117  4.5 Digital Signal Processing 119  4.6 Other MTI Delay Lines 126  4.7 Example of an MTI Radar Processor l'  4.8 Limitations to MTI Performance I ::> l)  4.9 Noncoherent MTI 138  4.10 Pulse Doppler Radar 130  4.11 MTI rrom a Moving Platform 140  4.12 Other Types of MTI 1-17  References 148  5 Tracking Radar I ,  5.1 Tracking with Radar 152  5.2 Sequential Lobing 153  5.3 Conical Scan 155  5.4 Monopulse Tracking Radar 160  5.5 Target-Reflection Characteristics and Angular Accuracy 167  5.6 Tracking in Range 176  5.7 Acquisition 177  5.8 Other Topics 178  5.9 Comparison of Trackers 18'..:  5.10 Tracking with Surveillance Radar 183  References 186  6 Radar Transmitters 190  6.1 Introduction 190  6.2 The Magnetron Oscillator 192  6.3 Klystron Amplifier 200  6.4 Traveling-Wave-Tube Amplifier 206  6.5 Hybrid Linear-Beam Amplifier 208  6.6 Crossed-Field Amplifiers 208  6.7 Grid-Controlled Tubes 211  6.8 Modulators 2 I •l  6.9 Solid-State Transmitters 21 l>  References 220  7 Radar Antennas 22.1  7. I Antenna Parameters 221  7.2 Antenna Radiation Pattern and Aperture Distribution 228  7.3 Parabolic-Reflector Antennas 235  7.4 Scanning-Feed Reflector Antennas 244  7.5 Lens Antennas 248 . 7.6 Pallcrn Synthesis  7.7 Cosecant-Squared Antenna Pattern  7.8 FfTccl of Frrors on Radiation PaHcrns  7.9 Radomcs  7.10 Stahilization of Antennas  References  8 The ElectronicalJy Steered Phased  Array Antenna in Radar  X. 
 `\\ \\P   4HE VECTOR % 
 However, progress was very slow and it was clear that the Ferranti equipment would not be available before the spring of 1943 at the earliest. The widespread introduction of the Metox warning receiver on theU-boats by the end of 1942, discussed in chapter 2, meant that there was an urgent need to improve ASV performance, including a change of wavelength. It was decided to utilise the H 2S, by then in production by EMI Electronics (The Gramophone Company) for Bomber Command. 
 L. Josefsson, “Phased array antenna technology for weather radar applications,” in 25th Conf.  on Radar Meteorol. 
 The klystron and the  traveling wave tube are of a different family known as linear beam tubes. ·~ Radars at VHF and UHF have often employed grid-controlled triode.and tetrode tuhes.  These have usually been, in the past, competitive in cost to other power generation means at  these frequencies. 
 TROL   AS EVIDENCED BY THE EXTENDED  VERTICAL  BOOM IN &IGURE  4HE ATTITUDE WAS STABLE TO LESS THAN n  TO WHICH THE ALTIMETERS PULSE 
 62. Hastings, C. E.: Raydist: A Radio Navigation and Tracking System, Tele-Tech, vol. 
 110. J. S. 
 The sum of all the voltages from the individiral  elements, when the phase difference between adjacent elements is $, can be written  E, = sin wt + sin (wt + \I/) + sin (wt + 2$) + ... + sin [cot + (N - I)$] (8.1)  where w is the angular frequency of the signal. The sum can be written  sin (N$/2)  Incoming siqnol  Figure 8.1 N-element linear array. 
 PHASE FILTER THAT USES FEWER PULSES 3TAGGER $ESIGN 0ROCEDURES  4HE INTERVAL BETWEEN RADAR PULSES MAY BE CHANGED  TO MODIFY THE TARGET VELOCITIES TO WHICH THE -4) SYSTEM IS BLIND 4HE INTERVAL MAY BE CHANGED ON A PULSE 
 Once the boundary conditions have been specified, the surface S is split into a collection of small discrete patches, as suggested in Fig. 11.22. The patches must be small enough (typically less than 0.2X) that the unknown currents and charges on each patch are constant or at least can be described by simple functions. 
 Ripple loss refers to the SNR loss incurred in active systems because of the fluctuation or ripple in the SNR that occurs as a target moves from range cell to range cell. Clutter rejection per- formance of a single waveform is evaluated on the basis of doppler response rather than range resolution; pulse compression provides a means for realizing increased range resolution and, hence, greater clutter rejection. In applications where an insufficient doppler frequency shift occurs, range resolution is the chief means for seeing a target in clutter. 
 Paynter, T. H. Lee, and W. 
 13,where itistreated atlength, will learn. Itisperhaps best here tosummarize theaspects ofsuper- rcfraction which have asignificant bearing onradar planning and design. 1.The guiding ofmicrowaves byrefractive anomalies ofthe duct type appears tobethesole means bywhich coverage beyond thehorizon can beobtained. 
 Real IF signal 2. Sampling waveform   (100 MHz) 3. Sampled signal 4. 
 TRAL ANALYSIS IS IMPLEMENTED BY PERFORMING THE DISCRETE &OURIER TRANSFORM $&4  4HE $&4 FORMS THE BASIS FOR MANY RADAR SIGNAL PROCESSING ALGORITHMS  SUCH AS DOPPLER PROCESSING AND FAST CONVOLUTION PULSE COMPRESSION DESCRIBED IN #HAPTER    AS WELL AS RADAR FUNCTIONS SUCH AS SYNTHETIC APERTURE RADAR 3!2  AND INVERSE SYNTHETIC APERTURE RADAR )3!2  4HE $&4 TAKES  . DATA SAMPLES REAL OR COMPLEX  AS INPUT AND GENER 
 FIERS  FILTERS  AND A MOTOR THAT MOVES THE ANTENNA IN A DIRECTION TO MAINTAIN THE ANTENNA AXIS ON THE TARGET 2ANGE TRACKING IS ACCOMPLISHED BY A SIMILAR SYSTEM TO MAINTAIN RANGE GATES CENTERED ON THE RECEIVED ECHO PULSES 4HIS MAY BE ACCOMPLISHED BY ANALOG TECHNIQUES OR BY DIGITAL 
 POWERED  COHERENT TRANSMITTING TUBES OR SOLID 
 Van Nostrand Company, Princeton, NJ., 1953, p. 265. 44. 
 DOMAIN REPRESENTATION OF THE WAVEFORM !LMOST ALL TYPES OF RADAR CAN BE ASSESSED NOT JUST BY THEIR SIGNAL 
 AMsidebands aretypically 120dBbelowthecarrier,asmeasured ina 1kHzband,andarerelatively constant acrossthe :'1.Jr;?' 1"~\'f,f.~''t'''~)'......,...,..):.,}.,....\....'. ~".t·.,:~'(: .~[\i..rl,l~t;~;J ::;'1--;::' .t<; , r'o''",•~: • 't" .~..'. ":f Figur£> ~.~i\N/MP{)·46('Wtf<lckcr-illuminatnr fortheHawkmissilesystemshowing separate transmit­ tingandreceiving antennas. 
 90. Butler, J. L.: Digital. 
 This is called pulse compression and allows the resolution of a short (wide-bandwidth) pulse with the energy of a long pulse. A CW waveform with frequency or phase modulation can also provide an accurate range measurement. It is also possible to measure the range of a single target by comparing the phase difference between two or more CW frequencies. 
 ch13.indd   40 12/17/07   2:40:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 TIONS v )%%% 3IGNAL 0ROCESSING -AGAZINE   VOL   NO   PP n  -AY  /N OCCASION  OF THE  " &RANKLIN -EDAL AWARDED TO " 7IDROW FOR PIONEERING WORK ON ADAPTIVE SIGNAL PROCESSING  3 (AYKIN AND ! 3TEINHARDT   !DAPTIVE 2ADAR $ETECTION AND %STIMATION  .EW 9ORK *OHN 7ILEY   3ONS  )NC    3 4 3MITH  h!DAPTIVE 2ADAR v IN  7ILEY %NCYCLOPEDIA OF %LECTRICAL AND %LECTRONIC %NGINEERING    * ' 7EBSTER ED   VOL   .EW 9ORK 7ILEY   UPDATED  *ULY    PP n  ! &ARINA  # ( 'IERULL  & 'INI  AND 5 .ICKEL EDS   3PECIAL )SSUE h.EW TRENDS AND FIND 
 In these  systems, amplitude fluctuations are removed by the phase detector. The operation of this type  of radar, which may be called coherent MTI, depends upon a reference signal at the radar  receiver that is coherent with. the transmitter signal. 
 One common form of  frequency hopped coding is known as Costas C oding. This is  a coding that intentionally reduces the side -lobes in the  periodic auto -correlation f unction and has advantageous performance in the presence of Doppler  effects . Additionally,  the variable frequency pattern used by  hopping pulses  reduce s susceptanc e to spoofing and jamming . 
 SPACE TARGET SCATTERING CROSS     
 Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 23.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 In addition to this database, bistatic reflectivity measurements have been made at  optical109 and sonic110 wavelengths and of buildings,111 airport structures,112 and plan - etary surfaces.2,52 In each of these measurements, the reflectivity data is expressed in  terms of reflected power, not sB0. 23.9 UNIQUE PROBLEMS AND REQUIREMENTS In the previous edition of this book, this section covered such hardware problems  as time and phase synchronization between transmitter and receiver constrained by  technology available in the 1980s. 
 Inradar sets where the r-fhead isaccessible toanoperator during operation, allofthe above metering can bedone onasingle meter and selector switch. The most important internal signal test point istheAFC video output. Onanoscilloscope thediscriminator output isseen, aswell asany spuri- oussignals. 
 POLARIMETRIC 4EC3!2  )SRAEL  n 8 -ULTIMODE. 
 TRACKING ERR OR IS BEST IN THE REGION     @    WITH A MINIMUM AROUND  )F ACCURACY FOR MANEUVERS IS THE DOMINANT  CONCERN  THEN ONE WOULD PROBABLY TUNE THIS FILTER TO  TO ACHIEVE THE LOWEST TOTAL ERROR FOR A  
 AM sidebands are typically  120 dB below the carrier, as measured in a 1 kHz band, and are relatively constant across the  Figure 3.3 AN/MP()-46 CW tracker-ill~irninator for the Hawk missile system showing separate transmit-  ring and receiving antentias. (('ortrresj* Raj~rlreorl ('0.).  CWANDFREQUENCY-MODULATED RADAR73 Theseparate antennas oftheAN!MPQ~46 CWtracker-illuminator of.theHawkmissile systemareshowninFig.3.3.TheCassegrain receiving antenna isontheright.Bothantennas havea"tunnel" aroundtheperiphery forfurthershielding. 
 Limitations of pulse compression. Pulse compression is not without its disadvantages. It re­ quires a transmitter that can be readily modulated and a receiver with a matched filter more . 
 30 - 34, 1960.  109. Skolnik. 
 TRACKING OUTPUT IS USUALLY OBTAINED FROM THE SHAFT POSITION OF THE ELEVATION AND AZIMUTH ANTENNA AXES !BSOLUTE TARGET LOCATION RELATIVE TO EARTH COORDINATES  WILL INCLUDE THE ACCURACY OF THE SURVEY OF THE ANTENNA PEDESTAL SITE 0HASED ARRAY INSTRUMENTATION RADAR  SUCH AS THE -ULTI 
   *ULY   $ "ILITZA  h)NTERNATIONAL REFERENCE IONOSPHERE v HTTPMODELWEBGSFCNASAGOVIONOSIRIHTML  )NDEX OF MODELSIONOSPHERICIRIIRI  HTTPNSSDCFTPGSFCNASAGOVMODELSIONOSPHERICIRIIRI  ! ' +IM  : & :UMBRAVA  6 0 'ROZOV  ' 6 +OTOVICH  9 3 -IKHAYLOV  AND ! 6 /INATS   h4HE CORRECTION TECHNIQUE FOR )2) MODEL ON THE BASIS OF OBLIQUE SOUNDING DATA AND SIMULATION  OF IONOSPHERIC DISTURBANCE PARAMETERS v  0ROC 886)))TH 523) 'ENERAL !SSEMBLY  .EW $ELHI   /CTOBER   2 % $ANIELL  *R AND $ . !NDERSON  h0)- MODEL  v HTTPMODELWEBGSFCNASAGOV IONOSPIMHTML  0ARAMETERIZED )ONOSPHERIC -ODEL  #OMPUTATIONAL 0HYSICS  HTTPWWWCPICOMPRODUCTSPIM  2% $ANIELL  ,$ "ROWN  $ . !NDERSON  - 7 &OX  0 ( $OHERTY  $ 4 $ECKER  * * 3OJKA   AND 2 7 3CHUNK  h0ARAMETERIZED IONOSPHERIC MODEL ! GLOBAL IONOSPHERIC PARAMETERIZATION  BASED ON FIRST PRINCIPLE MODELS v 2ADIO 3CIENCE  VOL   PP n    2 % $ANIELL  h02)3- ASSIMILATING DISPARATE DATA TYPES FOR IMPROVED LOW LATITUDE IONOSPHERIC  SPECIFICATION v PRESENTED AT THE )ONOSPHERIC $ETERMINATION AND 3PECIFICATION FOR /CEAN !LTIMETRY AND '03 3URFACE 2EFLECTION 7ORKSHOP AT THE *ET 0ROPULSION ,ABORATORY  0ASADENA  #!  n $ECEMBER   $ . !NDERSON  * - &ORBES  AND - #ODRESCU  h! FULLY ANALYTICAL  LOW 
 2, pp. 362-380, 1985. 5. 
 CHIRP TRANSMITTED  WAVEFORM )N &IGURE  B BOTH THE INPUT TRANSDUCER AND THE OUTPUT TRANSDUCER ARE DIS 
 Once mas - tered, however, quad-pol SAR data is the undoubted gold standard for quantitative  scene characterization by an imaging radar. A space-based quad-pol capability implies a significant cost. The driving require - ment is that the data must be mutually coherent. 
 PHASE APPROXIMATION TO QUADRATIC PHASE MODULATION !S - INCREASES  THE PEAK 
 2EJECT -IXER  ! CONVENTIONAL MIXER HAS TWO INPUT RESPONSES AT POINTS  ABOVE AND BELOW THE ,/ FREQUENCY WHERE THE FREQUENCY SEPARATION EQUALS THE )& 4HE UNUSED RESPONSE  KNOWN AS THE  IMAGE  IS SUPPRESSED BY THE IMAGE 
 For a large number of iterations, this product of cosines  converges to a value of 0.607253. In  most cases, this scaling can be compen - sated for in later stages of processing.  The inverse of this factor, 1.64676 for  a large number of iterations, is the pro - cessing gain imposed on the IQ results  of the CORDIC. 
 GETS BY THE THOUSANDS   e  4HE CLUTTER FILTERS MUST BE DESIGNED BASED ON SYSTEM PARAMETERS TO REJECT THE RADIAL SPEED OF THE hFIXEDv CLUTTER  3EE 3ECTIONS  AND     )T HAS BEEN OBSERVED THAT SOME PHASED ARRAY RADARS HAVE POOR  CLUTTER REJECTION  WHICH IS OFTEN CAUSED BY FAILURE   TO FOLLOW RULE . 
 Publ. no. 155. 
 13.11 ).44·45 In general, neither the Rayleigh nor the log-normal pd f's  accurately describe the statistics of real clutter, which usually lies between the two. The  Weibull pdf (Eq. 13.12), which is intermediate between the Rayleigh and the log normal, has  been suggested as applicable to land clutter. 
 Levanon and E. Mozeson, Radar Signals , New York: IEEE Press, John Wiley & Sons, Inc.,  2004, pp. 106–109. 
 The overall dc yield for this device may be as low as 30 percent when the processing yields for each step are accounted for; high-reliability screening that addresses visually detected imperfections may reduce that yield again by half. Transceiver Module Performance Characteristics. The partitioning of transceiver module circuit functions onto GaAs chips usually represents a tradeoff among several design issues, and the resultant circuit configurations represent a compromise among the goals of optimum RF performance, high levels of integration, and fabrication yields that are consistent with processing capabilities of GaAs MMICs. 
 Theintroduction ofdigitally switched phase shiftersemploying eitherfcrritesordiodesintheearly1960smadeasignificant improvement inthepracticality ofphasedarraysthatcouldheelectronically steered intwoorthogonal angular coordinates. 8.2BASICCONCEPTS Anarrayantenna consists ofanumber ofindividual radiating elements suitably spac,,:dwith respecttooncanother. ·l~alllpljtud~_l:l:!!~e-~l-1he-.signals..app.Jied toeachofthe elements arccontrolled toobtainthedesiredradiation patternfromthecombined actionofall theelements. 
 McInnes: Aperture Size and Ambiguity Constraints for a Synthetic Aperture  Radar, IEEE 1975 International Radar Conference, pp. 499-504, IEEE Publication 75 CHO 938- 1  AES. (Also available in ref. 
 Digital processing has emerged as the preferred means when the amount of data to be processed is not too great. Mechanization of SAR operations is often computation intensive. In cases not based on polar format, correlation operations have been used. 
 The TK in  the fired condition acts as a short circuit to prevent transmitter power from entering the  receiver. Since the TR is located a quarter wavelength from the main transmission line, it  appears as a short circuit at the receiver but as an open circuit at the transmission line so that  it does not impede the flow of transmitter power. Since the ATR is displaced a quarter  wavelength from the main transmission line, the short circuit it produces during the fired  condition appears as an open circuit on the transmission line and thus has no effect on  transmission. 
 If we simply reset the amplitudes under a value to 0, lower scatterings belonging to targets would be removed too. Although these low scatterings are not the main lobe, they reﬂect the scattering characteristics of the target. Therefore, they should be protected during the denoising. 
 55, pp. 2143-2159, December, 1967.  145. 
 Information abouttheradarbackscatter fromlandisrequired forseveraldifferent appli­ cations, eachofwhichhasitsownspecialneeds.Theseapplications include: (" Thedetectionofaircraft 01'£11'land,wheretheclutterechoesmightbeasmuchas50to60dB greaterthanaircraft echoes.MTIorpulse-doppler radariscommonly usedforthis application toremovethebackground clutter. Thedetection oIslI~face targetsoverland,wheremovingvehiclesorpersonnel canbeseparated fromclutterbymeansofMTI.Fixedtargetsrequirehighresolution fortheirdetection. Altimeters whichmeasure theheightofaircraftorspacecraft. 
 TION 4HE DIFFERENTIATOR HAS MINIMAL EFFECT ON NORMAL TARGETS BECAUSE OF THEIR SMALL EXTENT IN THE TIME DOMAIN 4HIS MEANS THAT TARGET VISIBILITY IS IMPROVED )T SHOULD BE NOTED THAT THIS TECHNIQUE DOES NOT GIVE SUBCLUTTER VISIBILITY 4HIS PROCESS IS CONVENTION 
 Spencer, C. Wu, and D. G. 
 75 -82, November 1977.  73. Waldman, J.: Millimeter arid Submillirneter Wave Receivers, U.S. 
 In this sense, the attention of the present work is on the signal modeling of the pulsar Crab Nebula emission and its passive inverse synthetic aperture radar application for asteroid imaging. The passive ISAR scenario, signal structure, power budget, image reconstruction and numerical experimental results are also discussed. The remainder of the paper is organized as follows. 
 Ifsynchronous frequency isnot essential, induction-motor drive ispreferable tothe greater complexity ofasynchronous motor. Itisgood practice, where possible, tomake input and output services identical, and toprovide means forbypassing theisolating setincase oftrouble. That is,ifthe main service is220 volts, 3-phase, 60cycles, the motor-generator set should be220-volt 3-phase input (60cycles) to220-volt 3-phase output (58cycles). 
 Also, the radar is more  subject to interference from nearby friendly transmitters.  The first sidelobe nearest the main beam is generally the highest. A typical parabolic  reflector antenna fed from a waveguide horn might have a first sidelobe 23 to 28 dB below the  main beam. 
 Whenthedetection processiscarriedoutautomatically byelectronic meanswithouttheaidofanoperator, thedetection criterion cannotbelefttochanceandmust becarefully specified andbuiltintothedecision-making devicebytheradardesigner. InChap.2theradardetection processwasdescribed intermsofthreshold detection. Almostallradardetection decisions arebaseduponcomparing theoutputofareceiverwith somethreshold level.Htheenvelope ofthereceiveroutputexceedsapre-established threshold, asignalissaidtobepresent.Thepurposeofthethreshold istodividetheoutputintoaregion ofnodetection andaregionofdetection; orinotherwords,thethreshold detector allowsa choicebetween oneoftwohypotheses. 
 Subcarriers. Although doppler filtering may be carried out at slightly higher levels, it is desirable to reject the signal produced by clutter and by spillover at the lowest level possible. Unfortunately, sufficiently high Q's are not available, even in quartz filters, to make it possible to reject clutter at, say, 30 MHz without diminishing the lower doppler frequencies as well. 
 TUDE DETERMINED BY A MAXIMUM FAST &OURIER TRANSFORM &&4  SIZE ALLOWED &OR RANGES BEYOND THE 2/ REGION AND ABOVE THE 0% REGION  AN EXTENDED OPTICS 8/  METHOD IS USED THAT IS INITIALIZED BY THE 0% MODEL AT THE MAXIMUM 0% ALTITUDE AND USES RAY OPTICS METHODS TO PROPAGATE THE SIGNAL TO HIGHER ALTITUDES #ONTINUITY  OF THE SOLUTIONS ACROSS  EACH REGIONS BOUNDARIES IS KEPT LESS THAN  D" BY CAREFUL SELECTION OF THE LIMITING 2/ GRAZING ANGLE AND THE MAXIMUM 0% PROPAGATION ANGLE 4HE PROPAGATION MODELS WITHIN !0- HAVE ALSO BEEN COMBINED WITH  OTHER ENVI 
 Oros, A. G. Shlionskiy, and O. 
 )NTERSCIENCE    2 - 'OLDSTEIN AND ( ! :EBKER  h)NTERFEROMETRIC RADAR MEASUREMENT OF OCEAN CURRENTS v  .ATURE  VOL   PP n    2 - 'OLDSTEIN  ( ! :EBKER  AND 4 0 "ARNETT  h2EMOTE SENSING OF OCEAN CURRENTS v  3CIENCE   VOL   PP n    ' & !DAMS ET AL  h4HE %2)- INTERFEROMETRIC 3!2 )&3!2 v IN  0ROCEEDINGS OF THE  )%%%  .ATIONAL 2ADAR #ONFERENCE    PP  2EPRINTED IN  )%%% !%3 3YSTEMS -AGAZINE    $ECEMBER    - 3KOLNIK   )NTRODUCTION TO 2ADAR 3YSTEMS ST %D  .EW 9ORK -C'RAW 
 In one design, an X-band passive receiver protector was capable of limiting  a l ns risetime, multi-kilowatt RF pulses to 1-W spike levels.53 . 366 INTRODUCTION TO RADAR SYSTEMS  In many radar systems the STC (sensitivity time control), which is a time-dependent  attenuator, is placed in the RF portion of the radar receiver rather than in the IF. When a  diode limiter is used in the receiver protector, the STC function can be readily incorporated by  inserting a variable bias into the limiter diodes to provide an attenuator that varies with  time.40.49 The PIN diodes serve the dual function of self-limiting during transmit, and act as a  variable attenuator, or STC, during receive. 
 * x  x  += REPRESENTS THE SET OF DOPPLER AMBIGUITY NUMBERS COVERING THE  MAXIMUM NEGATIVE AND POSITIVE DOPPLER 
 ( c) Vehicle. ( d) Top-hat.   (a)  (b) Figure 14. 
 DERIVED DATA  THEREFORE  ENHANCING INTEGRITY CHECKING ÓÓ°ÈÊ 1- 
 VOLTAGE   PLANE  AND THE BOUNDARIES OF THE ) 
 TheUnitedStatesarmedservices haveestablished63.67themaximum safecon­ tinuousexposure leveltobeanaverage powerdensityof10mW/cm2.Therehasbeensub­ stantial basisforsettingthislimit.However, whenworking underconditions ofmoderate to severeheatstressthemaximum exposure levelshouldbereduced appropriately.66 Thecriterion of10mWIcm1isbasedontheexperimental observation thatthermal effects aredominant. However, thereisevidence indicating thatnonthermal biological effectsalso occurfromexposure tomicrowave radiation.6BPulsedpowercanproduce biological change notobtained withCWpowerofthesameaverage value.Therefore, thepossibility ofdan­ gerouseffectswithexcessively highpeak'powersshouldnotbeoverlooked eveniftheaverage powerislessthanthesafethreshold. Therehasbeen,however, nodirectlinkmadebetween biological effectsattributed tononthermal microwave originandanadverse effectinhumans. 
 Alter: Atitomatic Detection and integrated  Trackiiig. IEEE 1975 It~tt~rt~c~rim~aI Rluiar Co~!/brc*ncr, pp. 39 1 -395. 
 Consequently, the vector sum, and therefore the ampli-  tude, change with changing target aspect.  Amplitude fluctuations of the echo signal are important in the design of the lobe-  switching radar and the conical-scan radar but are of little consequence to the monopulse  tracker. Both the conical-scan tracker and the lobe-switching tracker require a finite time to  obtain a measuremerlt of the angle error. 
 BLE THE RADARS RANGE (OWEVER  WHEN THERE IS CONSTRUCTIVE INTERFERENCE THAT INCREASES THE RANGE  THERE CAN BE DESTRUCTIVE INTERFERENCE THAT DECREASES THE RANGE DUE TO THE DEEP NULLS IN THE ANTENNA PATTERN IN THE ELEVATION PLANE ,IKEWISE  THE DESTRUCTIVE INTERFER 
 ARRAYS FOR RADAR PHASED 
 ING THE WIDTH OF THE FILTER RESPONSE  A FILTER DESIGN BASED ON  THE $OLPH 
   PP n    6 3 ,OSHCHILOV AND 6 ! 6OYEVODIN  h$ETERMINING ELEMENTS OF DRIFT OF THE ICE COVER AND  MOVEMENT OF THE ICE EDGE BY THE AID OF THE @4OROS SIDE SCANNING RADAR STATION v  0ROBL !RKTIKI  !NTARKT IN 2USSIAN   VOL   PP n     3 (AYKIN ET AL  2EMOTE 3ENSING OF 3EA )CE AND )CEBERGS  .EW 9ORK 7ILEY 
 However, the lower struts, #2 and #3, are tilted 60° with  respect to the E-field, and therefore appear smaller than their physical cross section. ch12.indd   14 12/17/07   2:31:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The limiting curve for zero relative speed is a straight line  perpendicular to the velocity vector. Figure 16.7 shows such a set of constant-doppler- shift contours. ch16.indd   14 12/19/07   4:55:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 On reflection from the surface the vertically  polarized component is attenuated more than the horizontal component, and it experiences a  different phase shift (Fig. 12.3). The result is that the horizontally polarizi:d component is  cancelled to a greater extent than the vertical component so that the original circular polariza­ tion is converted to elliptical polarization with the vertical component predominating.82  Assuming a 3.2° vertical beamwidth with cosecant-squared shaping up to 10°, theoretical  calculations give the following maximum cancellation ratios as limited by surface rdlcctions:  20.2 dB for sea, 23.6 dB for marsh, 27.2 dB for average land, and 34.1 dB for ctdert.8~ Other  calculations for ground-mapping radars, such as those used for airport surface-tralhc control,  indicate significantly worse cancellation limitations. 
 AGE 
 S. L. Durden, J. 
   PP n   *ULY   ( ! 7HEELER  h3IMPLE RELATIONS DERIVED FROM A PHASED 
 A matched filter in the receiver compresses the  signal in time   The most common pulse compression technique linear  frequency modulation, or LFM pulses.  A LFM pulse is one  where the pulse begins at one carrier frequency, then ramps  linearly, up or down  to an end frequency .  LFM pulses are  often called “chirps” or chirped p ulses. 
 Thesurface-reflected signaltravelsalongerpaththanthedirectsignalsothatitmaybe possible insomecasestoseparate thetwointime(range).Tracking onthedirectsignalavoids theangleerrorsintroduced bythemultipath. Therange-resolution required toseparate the directfromtheground-reflected signalis !1R=2hah, R(5.7) whereha=radarantenna height,h,=targetheight,andR=rangetothetarget.Foraradar heightof30m,atargetheightof100mandarangeof10km,therange-resolution mustbe 0.6m,corresponding toapulsewidthof4ns.Thisisamuchshorterpulsethaniscommonly employed inradar.Although therequired range-resolutions foraground-based radarare achievable inprinciple, itisusuallynotapplicaple inpractice. Theuseoffrequency diversity, asdescribed previously forreducing glint,canalsoreduce themultipath tracking error.AsseeninFig.5.16,theangleerrorsduetomultipath atlow anglearecyclical. 
 18.19 Block diagram of SCAMP, a single-channel monopulse tracking system, demonstrating angle tracking in one angle coordi- nate. (The system is capable of tracking in both coordinates.) (From W. L. 
 132. Giannini. R. 
 Amplitude fluctuations. Acomplex targetsuchasanaircraftorashipmaybeconsidered asa number ofindependent scattering elements. Theechosignalcanberepresented asthevector addition ofthecontributions fromtheindividual scatterers. 
 With such uncertainty in the  background, a nonparametric method of detection must be (A nonpararnetric  detector, also called a distribution-free detector, in its most general form does not require prior  knowledge of the probability density function of the noise or the signal.39) A nonparametric  detector permits a constant false-alarm rate to be achieved for background noise that might be  described by very broad classes of probability density functions. It has a greater loss than when  the character of the noise is known and an optimum detector can be designed, but it does keep  the false alarm rate fixed. One form of nonparametric detector is based on the "ranks" of  observations in which the components of the observations are ranked in order of magnitude,  and detection is basid only on some function of these ranks.3g This can be implemented with a  DETECTION OFRADAR SIGNALS INNOISE393 Vldpo Il1put1Tapped delayIineI~lliillTapped delaylineIcell Threshold I Sum I I Sum I I J !GreaterI IofI ICFAR output Figure10.11Cellaveraging CFAR.Inthisversionthegreateroftheoutputs rromtherangecellsaheador orbehindthecellofinterest isusedtosetthethreshold. 
 395–458.  6. F. 
 A given illuminator must re- main dedicated to its assigned target until the missile has achieved intercept; only then can it be reassigned to another. One of the primary reasons for active seek- ers is to remove this system firepower limitation, since each missile provides its own illumination. Another approach to avoiding the one-illuminator-one-target constraint is to use sampled data and time-share one illuminator (phased array or TWS) among several missiles. 
 OLDS THE MAIN CHANNEL  GUARD CHANNEL  AND MAIN 
 WPDF    .OTE THAT BOTH ACCURACY AND PRECISION ARE REQUIRED 2ADAR BACKSCATTER BY ITS VERY NATURE IS A QUANTITY HAVING A LARGE  STANDARD DEVIATION THAT CAN BE REDUCED ONLY BY EXTENSIVE AVERAGING "ECAUSE THE GEOPHYSICAL INTERPRETATION OF SCAT 
 For each peak detection, adjacent  amplitudes will be used to obtain an accurate ambiguous range estimate denoted ˆri,   where the subscript refers to the CPI number. Also, from the specific doppler filter  corresponding to the peak detection described above, the phase ( q1i) of the return is  saved. In addition, a corresponding phase ( q2i) obtained from an identical second dop - pler filter bank trailing (or leading) the detection filter bank by one pulse repetition  interval (PRI) is saved. 
 In RGPO, the target under track repeats  with delay and amplification the radar pulse so as to pull the radar range gate off the  target. The time delay is controlled so the false target is separated from the true one  with either linear or quadratic motion. For the linear case, the range of the false target  Rkft is related to the range of the true target Rkt via  R R v t tk kt kft po = + −( )0 (24.12) where vpo is the pull-off rate, tk is the time at which the target is being observed,  and t0 is the initial reference time of the RGPO false target. 
 It has been evaluated for specific antenna pat- tern functions and specific geometries by numerical integration techniques.42' '86 At small grazing angles a two-dimensional approximation to (Ac)b is a parallelo- gram shown as the single-hatched area in Fig. 25.4 with area RRk$RR-iA§r (A<)h - sinp (25-15) where RR AO/? is the cross-range dimension of the receive beam at the clutter cell, RT AO7- is the corresponding dimension for the transmit beam, and AO7^ and AO7- arc, respectively, the 3 dB beamwidth of the receive and transmit beams. Respective transmit and receive beam rays are assumed to be parallel, which is a reasonable approximation when the range sum is much greater than the baseline range, RT + R79 » L. 
 Burrows. C. R .. 
 IFY  BUT IN ORDER TO ACHIEVE THE REQUIRED SYSTEM PERFORMANCE  IT WAS THE ONLY OPTION AVAILABLE -ANY SYSTEMS WERE BUILT USING !PPLICATION 
 Module MTBFs greater than 100,000 h have been measured. 4. No pulse modulator is required. 
 The amplitude of the oscillation isdependent upon theenergy stored intheinductance at theend ofthesawtooth, which inturn isdetermined bythecurrent and hence bythe “area” under the sawtooth. Itcan berigorously proved byanalysis that this amplitude must besuch that the average voltage across theinductance (neglecting itsresistance) iszero during thewave- form. We shall becontent with the general statement that this must besosince, inthe absence ofresistance, the average potential across aninductance during acompletely closed cycle must bezero regardless of waveform. 
 AGC is used to remove the angle-error-detector-output dependence on echo amplitude and retain constant tracking loop gain. A typical AGC technique is il- lustrated in Fig. 18.16 for a one-angle coordinate tracking system. 
 19.2 are zero and all velocity vectors colinear.FEEDTHROUGH CLUTTER TARGET RECEIVER NOISESURFACE-TO-AIR (FIXED ILLUMINATOR) MISSILEVELOCITYTARGET VELOCITY DOPPLER FREQUENCY FEEDTHROUGH CLUTTER TARGET RECEIVER NOISEAIR-TO-AIR (MOVING ILLUMINATOR) LAUNCH A/CVELOCITY MISSILEVELOCITYTARGET VELOCITY DOPLER FREQUENCY . meaningless case.) This is different for a ground-based radar, where the outbound target is in the receding part of the spectrum, below feedthrough. The signifi- cance of the above discussion is that while approaching targets are in a clutter- free region of the spectrum, the receding target lies in the sidelobe clutter and must compete directly with it: if the clutter in the detection cell exceeds the tar- get, the target cannot be detected. 
 [ CrossRef ] 14. Lazecky, M.; Perissin, D.; Bakon, M.; De Sousa, J.M.; Hlavacova, I.; Real, N. Potential of satellite InSARtechniques for monitoring of bridge deformations. 
 TRACK AND CROSS 
 Ata later stage, the plots were passed byteletype tosave time. The whole computation process was completed inasecond orso. The operator then pressed abutton which connec Ledthegoniometer totheheight-finding antenna arrays. 
 SIONS  WHICH SHOWS THE GEOMETRY THAT GIVES RISE TO EACH RADAR MODE AND WAVEFORM   LISTS REPRESENTATIVE RADAR MODES  AND SHOWS TYPICAL MODERN AIRBORNE RADAR MODE INTER 
 Thus to esti~ilatc  I I I I I  -10 -5 0 5 10 15 20 25 30 I-  Signal lo noise roll0 per pulse - dB  Figure 2.25 Comparison of detectiorl probabilities for Rice, log normal, chi-square with m = 2 (Swerling  case 3) and nonfluctuating target models with ,I = 10 hits and false-alarm number n,.= lo6. Ratio of  dominant-to-backgrour~d equals unity (s = 1) for Rice distribution. Ratio of mean-to-med~an cross section  for Ing-normal distribution = p  THERADAR EQUATION 51 Thelog-normal distributioll liasalsoheenconsidered forrepresclIlillg targetechonuctua­ tions.Itcanbeexpressed as (2.42) a>O 1'(a)=.~-- exp!--~lI[n(~-)]2fl,.j21!Sda 12sdam whereSd=standard deviation ofIn(a/am)'andam=medianofa.Theratioofthemeantothe medianvalueofaisexp(sJ/2).Thereisnotheoretical modeloftargetscattering thatleadsto thelog-normal distribution, although ithasbeensuggested thatechoesfromsomesatellite bodies,ships,cylinders, plates,andarrayscanbeapproximated byalog-normal probability distribution.42.4.1 Figure2.25isacomparison oftheseveraldistribution modelsforafalsealarmnumber of \{)6whenallpulsesduringascanareperfectly correlated butwithpulsesinsuccessive scans independent (scan-to-scan fluctuation). 
 $ISTORTION 2ATIO 3).!$   3).!$ IS THE RMS SIGNAL AMPLI 
 On abscissa the indexes of the singular values, on the vertical axis the magnitude. The ﬁrst singular value is very high compared to the others showing that a large correlation was present in the raw data matrix and exploited in the ﬁrst left and ﬁrst right singular vectors. Figure 3. 
 ch17.indd   33 12/19/07   2:33:49 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 
 Air Force B-2 Spirit stealth bomber uses triangular patches. ch14.indd   18 12/17/07   2:47:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 TION AT SHORT AS WELL AS LONG RANGE 4HUS THE USE OF SOLID 
 TO 
 Imagine that a real  signal with a lowpass  signal spectrum of two-sided bandwidth B is plotted on a long  piece of paper, as shown in Figure 25.3 a. In the figure, the positive-frequency spectral  components of the signal are darkly shaded, and the negative-frequency components  are lightly shaded. To see the effect of sampling this signal at Nyquist rate B, the long  sheet is cut into smaller sheets, with the first cut at zero frequency and subsequent cuts  at sample-rate ( B, in this case) intervals in positive and negative frequency. 
 GRAPH IS SOLID OUT TO  NMI AND THEN DECREASES UNTIL IT IS ALMOST ENTIRELY GONE AT  NMI 4HE -4) IMPROVEMENT FACTOR IN BOTH PICTURES IS  D"  BUT THE INPUT DYNAMIC RANGE PEAK SIGNAL 
 The above applies for a square-law detector. Trunk55 has shown that the collapsing loss  for a linear detector differs from that of the square-law detector, and it can be much greater.  The comparison between the two is shown in Fig. 
 Height-finding bynulls, however, has inherent drawbacks which seriously reduce itsaccuracy inoperational use. The elevation pattern ofaground-based set must becarefully calibrated experimentally, because thereflection coefficient ofthesurrounding ground will determine thepattern, and because uneven ground gives different elevation patterns atdifferent azimuths. Further, changes inthe aspect presented tothe radar bythe aircraft may cause great changes intheecho strength. 
 ALARM PROBABILITIES  .OTE 4ARGET AND CLUTTER POWERS ARE MEASURED ON A SINGLE PULSE RETUR N AND ALL TARGET VELOCITIES  ARE ASSUMED EQUALLY LIKELY 4HE SUBCLUTTER VISIBILITY 3#6  OF A RADAR SYSTEM IS A MEASURE OF ITS ABILITY TO DETECT  MOVING 
     &IGURE A  WITH A SPECIFIED PRECISION OF  MILLIRADIAN 7ITH  HIGH POWER AND A HIGH GAIN ANTENNA  D"  AND SPECIAL TRACKING TECHNIQUES  THEY ARE THE WORKHORSE FOR PRECISION TRACKING OF SATELLITES AND SIMILAR TASKS (OWEVER  MOST MODERN TASKS REQUIRE PRECISION SIMULTANEOUS TRACKING OF MULTIPLE SIMULTANEOUS TARGETS WHERE USE OF MULTIPLE SINGLE TARGET TRACKING RADARS ARE NOT COST EFFECTIVE 4HE DEVELOP 
 ORBITING OCEANOGRAPHIC ALTIMETERS HAVE SEEN RELATIVELY LITTLE APPLICATION OVER NONAQUATIC SURFACES ! SATELLITE 
 The strong scintillation effect, which usually shown as streaks in SAR images, has been extensively reported by the Advanced Land Observing Satellite (ALOS)/the Phased Array-type L-band Synthetic Aperture Radar (PALSAR) system. The scintillation turbulence on both amplitude and phase will introduce serious spatial and frequency decorrelation within the SAR integration time and further distort the imaging performance. The former research usually focuses on the analysis of the scintillation effect for stripmap SAR systems [ 19–26]. 
 Keywords: wide-area surveillance; super-resolution; Doppler beam sharpening 1. Introduction Airborne or spaceborne wide-area surveillance (WAS) radar [ 1,2] can acquire a wide-area surveillance scene at a very short time, which is usually accomplished by steering the antenna beam from one azimuth angle to another. In the scanning movement of the antenna, the dwell time at each azimuth angle is very short to guarantee a high revisit radio. 
 CRAFT MEASUREMENTS REFERRED TO ABOVE    AUGMENTED BY DATA FROM A TOWER IN THE  .ORTH 3EA   WERE USED AS THE BASIS OF THE POWER 
 ORDER APPROXIMATIONS ! TYPICAL TASK FOR BISTATIC AIR SURVEILLANCE IS TO SELECT A BASELINE  , SO THAT A RECEIVER  WITH ANTENNA ALTITUDE  H 2 WILL MATCH EXISTING ,/3 COVERAGE OF A TRANSMITTER WITH ANTENNA  ALTITUDE H4 &OR THE WORST CASE  OVER 
 13.9a and b corresponds to clutter at a grazing angle of 90°, that is, for a radar looking straight down. On a strictly empirical basis, the clutter cross section at this angle is only weakly de FIG. 13.10 Dependence of clutter on wind direction: nominal wind speed, 15 kn; grazing angle, 45°. 
 13.8 Example of forcing a power-law fit (compare data with curves in Fig. 13.6). (From Chaudhry and Moore,31 © 1984, IEEE.)DOWNWINDFREQUENCY: 1OGHz ANGLEOFINCIDENCE: 40°N POLARIZATIONVPOLARIZATIONa;v(dB) UPWIND . 
 Kozma, A., E. N. Leith, and N. 
 Thus ifthe time constant were 50,000 Pscc while thepulse length was 1000 l,sec, the pulse would droop 2per cent. This isareasonably small amount, but ifthere were five such circuits incascade between the detector and the CRT, then thetotal amount ofdroop would be10percent. Although itisfairly easy tomaintain such long time constants provided RL+R* islarge, occasionally ithappens that RL+Rgisfairly small. 
           6J 6!!TJ!! )132 32 
 Berardino, P .; Fornaro, G.; Lanari, R.; Sansosti, E. A new algorithm for surface deformation monitoring based on small baseline differential sar interferograms. IEEE T rans. 
 128.Kclleher, K.S..andH.H.Hibbs:Organ-pipe RadarScanner, ElectrO/lics, vol.25,pp.126-127, May, 1952. 129.Pccler.G.D.M..K.S.Kelleher, andH.H.Hibbs:AnOrganPipeScanner, IRETrans.,no.PGAP-L pp.113-122. February, 1952. 
 The loop gain is dependent upon the number of the pulses th at must be integrated.  A  weighting is not possible.   a) +Loop Gain = k < 1 Delay LineInput Integrated Output Delay Line ΣInputIntegrated Output Σ+ -+ + 1-kb)   Figure 8.17  Loop integration: a) single -step (k<.9) b) dual -step (k<.98)  . 
 Figure 7. Barker c oded binary phase shift keying  (BPSK)   Another common pulse com pression technique employs  binary phase shift keying, or BPSK modulation, using a Barker  coded sequence  (see Figure 7).  Barker codes are unique  binary patterns that auto correlate against themselves at only  one point  in time. 
 The basic MTI concepts were introduced  during World War II. and most of the signal processing theory on which MTI (and pulse  doppler) radar depends was formulated during the mid-1950s. However, the reduction of  theory to practice was paced by the availability of the necessary signal-processing technology. 
 22. S. Musman, D. 
 P. Fox, A. P. 
 Gate  electrodes, or fingers  as they are often referred to, are generally grouped in logically  convenient substructures (cells) that are stepped and repeated to form a symmetric cor - porate hierarchy of combined transistors. The outputs of all fingers are required to be  combined in phase and then impedance-matched to the appropriate level. An industry- wide figure-of-merit for capability of the semiconductor and the unit FET is the power  output density, and this is given in units of watts/mm of total FET gate width or gate  periphery. 
 Proper amplifiers areprovided fordriving apair oforthog- onal coils (as indicated inFig. 12.3) or,alternatively, the deflecting plates ofanelectrostatic tube.. SEC. 
 Itwas found that under pulsed conditions oxide cathodes can emit asmuch as20amp/cm2 ascompared toabout 0.2amp/cm2 for d-cemission. More recently, currents ashigh as100amp/cm’ have been obtained. This current iscarried partly byprimary electrons and partly bysec- ondary electrons liberated from the“oxide cathode byback bombardment. 
 It increases linearlywithincreasing surface-roughness parameter (/it/!/A),levelsofftoamaximum andthendecreases astheinversesquarerootoftheroughness parameter.74 Thepresence ofareflecting surfaceaffectsthemeasurement oflowelevation anglesaswell astheradarcoverage. Whenthetargetelevation angleislessthanabeamwidth, theradar receives boththedirectandtheground-reflected waves,andtheeffective antenna patternis altered.Theradarseestheimageaswellasthetarget.Height-finding radarswhichmeasure. 446 INTKODUCTION TO RADAR SYSTEMS  elevation angle of arrival by comparing the amplitudes of the signals received at two differcut  beam elevation angles (lobe comparison) can give erroneous and an~biguo~is mcasurenicnts at  low angles.".75 Elevation errors near the ground may be considerably reduced in magnit~rdc  and the ambiguities eliminated by surrounding the radar with a metallic fence to remove the  ground-reflected wave. 
 Thus, a  loss of 1.0 dB corresponds to MBt = 100. The ratio of the bandwidths M therefore can be  unity when Br is large enough.73 Both coded-pulse waveformsss and frequency-modulated  waveforms have been considered for pulse compression radar with CFAR.~~  The benefits of a large Br for CFAR can also be obtained without transmitting a pulse-  compression waveform.87 A conventional pulse waveform can be transmitted, and on recep-  tion the received signal passed through a dispersive delay line (a pulse expansion network) that  spreads the signal over a duration T. The output of the dispersive filter is hard limited and fed  to a second dispersive delay line with a characteristic inverse to the first. 
 Tech. Rept. 13, Contract DA-36-039 sc-15358, June, 1953. 
 39.Shrader, W.W.:MTIRadar,chap.17of"RadarHandbook," M.I.Skolnik(ed.),McGraw-Hill Book Co..NewYork,1970. 4D.Ward.H.R.:Dispersive Constant FalseAlarmRateReceiver, Proc.IEEE,vol.60,pp.735-736. June, 1972. 
 02& RANGE 
 Radar networking systems  are generally characterized by what radar data are shared and how they are correlated  and fused. The two most common ways of combining radar data are as follows: ch07.indd   46 12/17/07   2:14:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 For example, after initial crossing of the detection threshold, the radar beam can be  returned to the same direction sooner than it would in normal search in order to verify that a  target was indeed detected and that the threshold crossing was not a false alarm due to noise.  This ~.rrlficoatiotl plrlst. can be of greater power and/or of longer duration to increase the  probability of detection. 
 The coaxial output line ends ina probe which isinserted inthe waveguide toform amatched transition like that shown inFig. ll”12a. 11.8. 
 xiii. Author biography Simon Watts Simon Watts graduated from the University of Oxford in 1971, obtained an MSc and DSc from the University of Birmingham in1972 and 2013, respectively, and a PhD from the CNAA in 1987. He was deputy Scienti ﬁc Director and Technical Fellow in Thales UK until 2013 and is a Visiting Professor in the department of Electronic and Electrical Engineering at University College London. 
 For higher power levels, overall device impedances become lower and lower. For example, the real part of the input impedance for a 24-mm chip would be less than 1 ohm. 3. 
 L.: The Role of TimeIFrequency in Navy Navigation Satellites, Proc. IEEE, vol. 60. 
 SNR loss. Weighting in other cases is applied by a mismatch of the receiver amplitude characteristic. Item 2, Dolph-Chebyshev44 weighting, is optimum in the sense of producing the minimum main-lobe width for a specified sidelobe level. 
 Ó°{Ó  2!$!2 (!.$"//+  &)'52%   6ELOCITY RESPONSE CURVE THREE 
 271-288, April, 1953.  4. Collins, G. 
 TIME ADAPTED !%3! WITH TWO DIFFERENT SCAN REGIMES FOR THE SAME AMOUNT OF INPUT PRIME POWER !%3! PERFORMANCE FALLS OFF FOR LARGE SCAN COVERAGE BECAUSE OF THE LOWER PROJECTED APERTURE AREA FOR A FIXED MOUNTING AS SHOWN IN &IGURE  ! MECHANICAL SCAN HAS THE SAME PROJECTED AREA IN ALL DIRECTIONS AND LARGE SCAN ANGLES MARGINALLY REDUCE RADOME LOSSES  WHICH RESULTS IN SLIGHTLY IMPROVED LARGE ANGLE PERFORMANCE .ONETHELESS  !%3! PERFORMANCE IS USUALLY SUPERIOR INSIDE  &)'52%  %XAMPLE !%3! MANAGEMENT COMPARISON ADAPTED    . x°£ä  2!$!2 (!.$"//+  A on AZIMUTH SCAN   5SUALLY  A FIGHTER CANT ENGAGE AT LONG RANGE OUTSIDE THIS  AZIMUTH FOR KINEMATIC REASONS 4HE PERFORMANCE DIFFERENCES DEPICTED IN &IGURE  ARE THE RESULT OF THREE FACTORS  THE INSTALLED APERTURE CAN BE  LARGER IN NET PROJECTED AREA AT THE AIRCRAFT IN 
 128] PROTECTION AGAINST EXTRANEOUS RADIATIONS 457 curve ofthe cavity. Under actual conditions ofloading, the width Aj between half-power points iscommonly about + ofthe resonant fre- quency itself. Any control circuit that will lock the beacon local oscillator atthe topoftheresonance curve must insome manner take aderivative ofthe curve. 
 With planar arrays, scanning is limited by the loss in gain and the increase in beamwidth corresponding to the reduction of the ap- erture to its projected area. Practical extreme values of scanning are therefore in the region of 60 to 70°. A minimum of three planar array apertures is then nec- essary for hemispherical coverage. 
 The number of codes listed in Table 10.4 is the number of codes, not including the allomorphic forms, which have the same minimum peak sidelobe. For example, the following 7-bit Barker codes all have the sameTIME TIME . TABLE 10.4 Optimal Binary Codes *Each octal digit represents three binary digits: 0 000 4 100 1 001 5 101 2 010 6 110 3 Oil 7 111Length of code N 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40Magnitude of minimum peak sidelobe 1 1 1 1 2 1 2 2 2 1 2 1 2 2 2 2 2 2 2 2 3 3 3 2 3 3 2 3 3 3 3 3 3 3 3 3 3 3 3No. 
 Again these coherent gain values would usually differ from filter to  filter due to potentially different doppler filter characteristics. These coherent gain  values will include the filter mismatch loss but not the straddling losses between  adjacent filters. The product of the clutter attenuation, CAi, and the coherent gain,  GCmax, i, for the i’th doppler filter becomes the definition of the signal-to-clutter ratio  (SCR) improvement:  I C A Gi i C i SCR, max, = ⋅  (2.20) This quantity was not included in the IEEE Dictionary,15 but the following defini - tion is commonly used: signal-to-clutter ratio improvement: ( ISCR): The ratio of the signal-to-clutter ratio obtained  at the output of the doppler filter bank to the signal-to-clutter ratio at the input to the filter bank  computed as a function of target doppler frequency. 
 MS PULSE AND A   BEAMWIDTH FOR EQUAL PERFORMANCE IN A DISTRIBUTED CLUTTER ENVIRONMENT 4HE SUBCLUTTER VISIBILITY OF A RADAR  WHEN EXPRESSED IN DECIBELS  IS LESS THAN THE  IMPROVEMENT FACTOR BY THE CLUTTER VISIBILITY FACTOR 6 OC SEE DEFINITION BELOW  )NTERCLUTTER 6ISIBILITY )#6   4HE )%%% DEFINITION IS INTERCLUTTER VISIBILITY 4HE ABILITY OF A RADAR TO DETECT MOVING TARGETS THAT OCCUR IN RESOLUTION  CELLS AMONG PATCHES OF STRONG CLUTTER USUALLY APPLIED TO MOVING TARGET INDICATION -4)  OR PULSED 
 LAR POLARIZATION 4HE CLASSICAL MEASURE OF THIS EFFECT IS THE CIRCULAR 
 Crum, R. E. Saffle, and J. 
 The components in each channel need only have a bandwidth 1/N times the total  processing bandwidth. Still another advantage of such systems is that a strong CW interfer. 432 INTRODUCTION TO RADAR SYSTEMS  enoe signal will only suppress the target signal in one of the N channels. 
 There are nohigh pulse powers and both intermediate- and audio- frequency amplifiers arenarrow-band. Gains per stage are limited by stability rather than bybandwidth; inother words, the technique is like that ofordinary radio rather than like that oftelevision. Because ofthe large size ofthe leakage signal relative tothe target signal, only. 
 TERED IN PRACTICE "UT WHILE THE PARAMETERS RELATING TO THE RADAR SYSTEM AND ITS CONFIGU 
 In fact, it need not he  confined to the physical extent of the target and may be off the target a significant fraction of  the time. The random wandering of the apparent radar reflecting center gives rise to noisy or  jittered angle tracking. This form of tracking noise is called angle noise, arlgle scintillatiorls,  angle juctuations, or target glint. 
 2017 ,54, 797–818. [ CrossRef ] 4. Zhu, L.; Gong, H.L.; Li, X.J.; Wang, R.; Chen, B.B.; Dai, Z.X.; Teatini, P . 
 RADAR CLUTTER 505  it cannot accept the backscattered echo signal from a sphere or a plane sheet, since the direction  of the polarization is reversed on reflection; that is,.if right-hand circular polarization is trans­ mitted, spherical raindrops reflect the energy as left-hand circular polarization. If the same  antenna is used for both transmitting and receiving, the antenna is not responsive to the  opposite sense or rotation and the echo energy will not appear at the receiver. A target such as  an aircraft, however, will return some energy with the correct polarization as well as energy  with the incorrect polarization. 
 ¤ ¦¥³ µ´§ ©¨ ¨¶ ¸· ·  N    WHERE  U   WIND SPEED  JC   GU  M     AND AE    4HE EXPONENTIAL TERM APPROXIMATES THE DECAY IN THE SPECTRUM FOR WAVE SPEEDS  ABOVE THE WIND MAXIMUM VELOCITY -ODELS THAT TAKE ACCOUNT OF THE CONSEQUENCES OF  FINITE FETCH AND FINITE DURATION OF THE WIND STRESS INCLUDE THE */.37!0 SPECTRUM  AND THE MODEL OF %LFOUHAILY ET AL SUCH EFFECTS CAN LEAD TO SUBSTANTIAL CHANGES IN THE  (& DOPPLER SPECTRUM AND HENCE TARGET DETECTABILITY  SO THESE MODELS SHOULD BE USED WHEN APPLICABLE 4HE DECREASE OF WAVE SPECTRAL DENSITY WITH WAVENUMBER IS OBSERVED TO LIE CLOSE  TO A K n POWER LAW  AS ADOPTED BY MOST MODELS  AND BY A NATURAL COINCIDENCE  THIS IS  BALANCED BY THE K FACTOR IN THE FIRST 
 Each element has its own phase shifter. A separate command  must be computed by the beam-steering computer and distributed to each phase shifter. The  power distribution to the columns is by parallel feed. 
 November. 1974.  91. 
 PULSE DOPPLER RADAR  4.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 Ground Clutter in a Stationary Radar.  When the radar is fixed with respect  to the ground, both stationary main-beam and sidelobe clutter returns occur at zero- doppler offset from the transmit carrier frequency. The sidelobe clutter is usually  small compared with main-beam clutter as long as some part of the main beam  strikes the ground. 
 Experimental measurements87indicate thatwhenanaircraft isillu­ minated withonesenseofcircularpolarization, theechopoweronastatistical basisisdivided moreorlessequally between right-hand andleft-hand circular polarization. Withlinear polarization, theamountofenergyconverted totheorthogonal polarization isabout0.5dB. Thusthenetlossofaircraft-echo power-onchanging fromlineartocircular polarization is about2.5dB.Insomecases, however, a·greatervalueofradarcrosssectionmaybeobtained withcircular polarization rather,thanwithlinear.79 Analternative tocircular polarization istotransmit anylinearpolarization andreceive ontheorthogonal linearpolarization.79.IHSpherical raindrops willgivenoretllrninthl.: orthogonal channel ifnocross-polarization distortion takesplaceintheradarorthepropaga­ tionmedium. 
 Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar.  AN INTRODUCTION AND OVERVIEW OF RADAR  1.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 Commission, and internationally, the International Telecommunications Union). After  the success of radar in World War II, radar was allowed to operate over about one- third of the microwave spectrum. 
 1123–1130, November 1971. 59. F. 
 The roll-off continues approxi - mating J0(x)/x down to b ≈ 130°, where J0 is a Bessel function of zero order. A linear  aperture of length D, with aspect angle orthogonal to the transmitter LOS, will roll off  3 dB at (p − b ) = l /2D, when D/l 1. The forward-scatter RCS rolloff continues,  with sidelobes approximating sin x/x over the forward-scatter quadrant ( b > 90°).30  For other aspect angles and targets with complex shadow apertures, calculation of the  forward-scatter RCS rolloff usually requires simulation. 
 The purpose of Fig. 3.1 is to illustrate the usual sequence of processing func- tions that may occur in any radar receiver and the variety of possible outputs, although no radar receiver will include all these functions or provide all these out- puts. Virtually all radar receivers operate on the superheterodyne principle shown in Fig. 
 14. Greene, J. C., and J. 
 T/P was formally decommissioned in December 2005. As is true for most radars, the received waveform produced by an individual pulse  from TOPEX was corrupted by coherent self-noise known as speckle. The standard  deviation of speckle is reduced by summing (averaging) many statistically independent  waveforms together. 
 A constant rate of change of phase with time is  e4uivalent lo a constant frequency. Thus a frequency difference at adjacent elements results in  a scanning heam. If the LOs in the mixers of Fig. 
 ANGLE ERROR WHEN THE TARGET ELEVATION GOES TO ZERO )T ALSO CAUSES SOME SIGNIFICANT AZIMUTH ERROR  #ROSSTALK #AUSED BY #ROSS 
 PEAK PHASE RIPPLE &REQUENCY MULTIPLIERS CAN BE IMPLEMENTED USING A VARIETY OF TECHNIQUES  SUCH AS  USING STEP RECOVERY DIODE MULTIPLIERS OR USING PHASE LOCKED LOOPS 7HERE WIDE PERCENT 
 BAND RADAR WITH STRETCH PROCESSING  BANDWIDTHS OF    -(Z   AND  -(Z 4HE  WIDEBAND WAVEFORM HAS A SWEPT BANDWIDTH OF  -(Z  TO A PULSEWIDTH OF APPROXI 
 Fante et al., “A parabolic cylinder antenna with very low sidelobes,” IEEE Trans ., vol. AP-28,  pp. 53–59, January 1980. 
 A ground-based radar that operates without benefit of a radorne must be  designed to withstand wind loads.'09 ' l3 Surveillance radars must not only be able to operate  in strong winds, but must rotate uniformly. Rotating antennas outside of radomes cannot be  operated at winds that are too great. They sometimes have to beshut down and securely fastened  in strong gale winds. 
 direction the antenna must be moved in order to align the switching axis with the direction or  the target. When the voltages in the two switched positions are equal, the target is on axis and.  its position may be determined from the axis direction. 
 PLUS 
 Generally, target classification by radar involves examining the  detailed structure of the echo signal.· It usually requires a larger signal-to-noise ratio than  normally needed for detection.· Thus the range at which target classification can be made is  often less than the range at which the target can be first detected.  High-range-resolution. A short-pulse. 
 However, the reduction in impulse  duration is achieved at the expense of efficiency and loaded antennas may have effi - ciencies as low as 10%. The types of antennas that are useful to the designer of ultrawideband radar fall  into two groups: dispersive antennas and nondispersive antennas. Dispersive antennas  have a nonlinear phase/frequency response whereas nondispersive antennas have a  substantially linear phase/frequency response. 
 (14.33). Any of the methods for measuring range with  a monostatic radar can be applied to bistatic radar, including pulse and FM-CW modulations.  If the direct signal from the transmitter is available at the receiving site, it can bc trsed as a  reference sig~~al to extract the doppler frequency shift. 
 Meteorological Radar   .............................................. 23.1  23.1 Introducti on  .............................................................  23.1  23.2 The Radar Range Equation for Meteorological  Targets  ................................................................... 
 PHASE NOISE TRANSMITTERS AND RECEIVER COMPONENTS  AND SIGNAL PROCESSORS HAVING SIGNIFICANT GROUND CLUTTER REJECTION CAPABILITY 4HE .EXRAD RADAR SYSTEM  WITH ITS HIGH QUALITY ANTENNA AND  D" OF CLUTTER REJECTION  IS WELL SUITED TO THIS IMPORTANT OPERATIONAL TASK 2EFRACTIVITY AND 7ATER 6APOR -EASUREMENTS  #ONVENTIONAL WEATHER RADAR PRO 
 STAGE LOW 
 Its principle was known and  demonstrated many years before the development of practical monostatic radar. In Sec. 1.5 it  was mentioned that the first "radar" observations in both the United States and in Great  Britain were made with separated CW transmitters and receivers. 
 Figure 4.14. (a) Leigh Light operator ’s position, showing azimuth (A) and elevation indicators [ 10]. (b) Close- up of the azimuth indicator, showing the outer marker with scanner bearing [ 1].Airborne Maritime Surveillance Radar, Volume 1 4-13. 
 Slowly varying voltage proportional tothe scan angle, tobeused inthecartesian display ofangle asintype Band type Cdisplays. The voltages can beobtained directly from apotcntiomctcr of proper characteristics orfrom the envelope ofacarrier which has been properly modulated. Inmany cases where the angle dis- played issmall, sin0can besubstituted for0. 
 Scan Loss.  Broadside electronically scanned array antennas are subject to reduc - tion in gain when the main beam is scanned off broadside. The projected area of the  ESA aperture decreases as beam scans from broadside. 
 Newburgh, R. G.: Basic Investigations of the RADAM Effect, Rome Air Development Center, New  York, Report RADC-TR-78-151, June, 1978, AD A058099. (Approved for public release.)  440INTRODUCTION TORADAR SYSTEMS 45.Hynes,R.,andR.E.Gardner: Doppler SpectraofSBandandXBandSignals,IEEETraIlS.SlIppl., vol.AES-3,no.6,pp.356-365, Nov.,1967.Also,ReportofNRLProgress, pp.1-10,January, 1968,PB 177017. 
 INTENSITY VARIATIONS LIKE  THOSE IN PHOTOGRAPHS &OR THIS REASON  PHOTOINTERPRETERS CAN EASILY LEARN TO INTERPRET RADAR IMAGES (OWEVER  SINCE THE RADAR IMAGES ARE DUE TO MICROWAVE REFLECTIVITY  NOT OPTICAL REFLECTIVITY  THE INTERPRETERS MUST UNDERSTAND THE DIFFERENCES AND THAT THE IMAGES AT THE DIFFERENT WAVELENGTHS ARE  IN FACT  COMPLEMENTARY -OREOVER  THE GEOMETRICAL DISTORTIONS FOR RADAR IMAGES ARE THOSE OF A SIDE 
 13. Ti,e effects of propagation will modify the free-space performance of the radar. as  well as introduce errors in the radar measurements. 
 7. Taylor, J. W., Jr., and J. 
  ARE A FAMILY OF , BAND  LONG 
 Forward-shot chaff  car1 deceive the range and velocity tracking gates of tracking radars.  Tl~e effects of chafican be reduced by a ptoperly designed MTI. The design of an MTI to  detect ~iiovirig targets in char is different from the design of an MTI for surface clutter since  the chaff is generally ill motion. 
 Hounam, M. Werner, S. Riegger, and E. 
 Repr. 54-27. June 15. 
 The usual rule-of-thumb criterion employed in antenna practice is that the.  phase of the actual wavefront must not differ from the phase of the desired wavefront by more  than ± 1/16 in order to ensure satisfactory performance. The application of this criterion to a  reflector antenna requires the mechanical tolerance of the surface to be within ± l/32. 
 Geophys. Res. Oceans 1997 ,102, 25237–25250. 
 Mechanically actuated phase shifters are, of course, not capable of being actuated as  rapidly as electronic devices, nor are they as flexible in being able to select any random value of  phase. It is possible, however, with several electromechanical devices to scan a beam over its  coverage at rates as fast as 10 times per second (0.1 s switching time), which is sufficiently rapid  for many applications.  \_.j~FREQUENCY-SCAN ARRA YS63-65  A change in frequency of an electromagnetic signal propagating along a transmission line  produces a change in phase, as was indicated by Eq. 
 Atthereceiving 1Itisnotsatisfactory tousesuch along delay between the basic pulse and the azimuth pulse since small percentages of“jitter” ordrift become too important.. 696 RADAR RELAY [SEC. 17.6 station thetwo areseparated byappropriate a-ffalters, and thereference signal ispassed through afrequency multiplier. 
 2, 1989. 62. D. 
 342 1NTKODUCTli)N TO RADAR SYSTEMS  134. Hansen, R. C.: Workshop on Conformal Arrays, Microwur!e J., vol. 
 The  output of the integrator is applied to a threshold-detection circuit. Only those signals which  cross the threshold are reported as targets. Following the threshold detector, the outputs from  each of the range channels must be properly combined for display on the PPI or A-scope or for  any other appropriate indicating or data-processing device. 
 ch04.indd   53 12/20/07   4:54:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 "' 9.75 X 4.875 "'?" -61/6. id i;O \ 11.5 X 5. 75  ,•fl ~' 9 '\. 
 It also has a suite of feed models to  draw upon and has tools to enable feed array modeling. Figure 12.35 shows a snapshot  of the GRASP GUI window, including a rendering of an array-fed reflector and its  associated beam rosetta, i.e., an overlay of beams associated with each of the indi - vidual array feeds. Some other notable features of the GRASP code include scattering  models for mesh, frequency selective or lossy reflector surfaces, and a spherical wave  expansion (SWE) feature for modeling of systems wherein the reflector or scatterer is  in the near field of the feed source. 
 8.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 where td is the time delay of the midpoint of the signal measured relative to the mid - point of the reference waveform. For the case shown, where the RF carrier frequency  is above the carrier frequency of the reference waveform, a positive time delay results  in a negative frequency offset. The signals at the correlation mixer output are then  resolved in the frequency domain by spectral analysis processing. 
 CALIBRATED *ASON 
 TIONS FOR TARGET MOTION EG  CONSTANT ACCELERATION OR CONSTANT VELOCITY  &IGURE  SHOWS A BANK OF MULTIPLE PARALLEL FILTERS ALL FED BY THE SAME STREAM OF ASSOCIATED MEA 
 (From Daley.21)RAYLEIGH LOG NORMALPERCENT OF SAMPLES EXCEEDING ABCISSA . data, represented by the solid line, is plotted on normal probability paper with Rayleigh and log-normal distributions shown for comparison (dashed lines). The ordinate is the percent of time by which the abscissa is exceeded, and the ab- scissa is the value of <j° as defined by Eq. 
 BEAM INSTRUMENT  COMPRISED OF TWO SETS OF TWO DUAL 
 Since TR-tube conditions aredifficult toreproduce,. 414 RFCOMPONENTS [SEC. 11.7 crystals are tested bysending through them ad-c pulse ofduration 2.5X10–gsec and total energy ofthe order ofanerg. 
 Thelargerthenumber oftargets,themoredifficult istheproblem ofcorrelating theechoesfromeachofthetwo beams.Thecloserthebeams,theeasier..it istocorrelate theechoes,butthelesstheaccuracy. Another usefulmodification istoseparate thebeamsatzeroelevation sothatthedatafrom theverticalandtheslantbeamdonotappearcloseintime.. OTHER RADAR TOPICS 543  Monopulse. 
 4.Atmospheric effects. Atmospheric absorption and variations in refraction can beneglected over the wavelength region under consideration, but the scattering ofradiation from water droplets giving rise toechoes from storw centers isaneffect ofconsider- able importance (Sea. 3“10). 
 IDEAL FILTER RESPONSES 4HE EFFECT ON PASSBAND RESPONSE IS TYPICALLY NEGLIGIBLE  BUT SIGNIFICANT DISTORTION OF THE FILTER STOPBAND REJECTION CAN OCCUR  POTENTIALLY EFFECTING )1 BALANCE $IGITAL  $OWNCONVERSION  5SING  -ULTIRATE  0ROCESSING  AND  0OLYPHASE   FILTERS 4HERE ARE MANY VARIATIONS TO THESE BASIC APPROACHES  AND SPECIFIC IMPLE 
 Parabolic-Cylinder Antenna.2'16'17 It is quite common that either the elevation or the azimuth beam must be steerable or shaped while the other is not. A parabolic cylindrical reflector fed by a line source can accomplish this flexibility at a modest cost. The line source feed may assume many different forms ranging from a parallel-plate lens to a slotted waveguide to a phased array using standard designs.2"4 The parabolic cylinder has application even where both patterns are fixed in shape. 
 ,OBE  #ANCELER v 53 0ATENT     !UGUST   . 
 NOISE RATIO 3.2   PERFORMANCE REFERRED TO A BANDWIDTH EQUAL TO THE !$ SAMPLING RATE /FTEN THIS 3.2  IS NOT AS HIGH AS ONE WOULD EXPECT BASED ON THE NUMBER OF BITS USED BY THE !$  CONVERTER 3OMETIMES THE ACTUAL PERFORMANCE OF AN !$ CONVERTER IS CHARACTERIZED BY AN EFFECTIVE NUMBER OF BITS  SMALLER THAN THE ACTUAL NUMBER OF BITS AND CORRESPOND 
 Schneider, A. B., and P. D. 
 STATE TECHNOLOGY FOR USE IN THE COMMON RADAR FREQUENCY RANGES 4HE ADVANTAGES OF SOLID 
 HOP PATHS &IGURE  GIVES NIGHT AND DAY EXAMPLES OF IONOGRAMS SHOWING THE IONOSPHERE  KM DOWNRANGE FROM A RADAR LOCATED AT  n. AND  n7 LOOKING EAST  IN SUMMER AT A MEDIAN SUNSPOT NUMBER OF  4HE COR 
 2'0/ 4!2'%4 ./,/34 4!2'%43 4S S  4AVE S  0- 7 0/3 %22 M 6%,%22 MS       n           n       n  .   %,%#42/.)# #/5.4%2 
 Ocean. Eng., vol. OE-5, pp. 
 There are two classes of track formation algorithms: 1. Forward-tracking  algorithms  basically propagate one hypothesis forward in time,  recursively checking for “target-like” motion. Detections that do not correlate with  clutter points or tracks are used to initiate new tracks. 
 Many configurations are computationally equivalent. More flexibility in locating zeros and poles is achieved with delays in pairs as shown for the second and third delays of the triple canceler. (In this configuration, the zeros are con- strained to the unit circle.) The triple-canceler configuration is such that two of the zeros can be moved around the boundary of the unit circle in the Z plane. 
 $ETECTION 34# IN A -EDIUM 02& 0ULSE $OPPLER 2ADAR v 53 0ATENT      % &ROST AND , ,AWRENCE  h-EDIUM 02& 0ULSE $OPPLER 2ADAR 0ROCESSOR FOR $ENSE 4ARGET  %NVIRONMENTS v 53 0ATENT     7 ,ONG AND + (ARRIGER  h-EDIUM 02& FOR THE !.!0' 
 Downey. E. J., R.H. 
 IRE. vol. 35. 
 Here T R cR= ⋅2 /  is the time FIGURE 2.73  Power amplifier simplified block diagram FIGURE 2.74  Pulsed oscillator simplified block diagram ch02.indd   67 12/20/07   1:45:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 M.: Final Engineering Report on Angular Accuracy Improvement, General Electric  Co. Report 011 Contract D.A. 36-039-sc-194, Aug. 
 SIBLE ! CONDUCTING SCREEN EMBEDDED IN THE ASPHALT MAY IMPROVE THE REFLECTION 0AVING ALSO REDUCES MAINTENANCE OF THE GROUND PLANE  SUCH AS MIGHT BE REQUIRED BY PERIODI 
 88 tobederived bythe use ofthis more complicated system isrelative freedom from random triggering byother radar sets inthesame band since the probability ofgetting such agroup ofpulses byaccident decreases rapidly asthe complication ofthe group increases. This matter isdis- cussed more fully below. Allsuch systems, however, aresubject tosome difficulties resulting from thepresence ofreflected signals that aredelayed because ofthe longer path traversed. 
 Following the CFAR is the sidelobe discrete rejection logic, discussed in Sec. 17.2, and the range and velocity ambiguity resolvers (if used). The final detection outputs are passed to the radar display and computer. 
 The antenna pattern is a plot of antenna gain as a function of the direction of radiation. (A  typical antenna pattern plotted as a function of one angular coordinate is shown in Fig. 7.1 .)  Antenna beam shapes most commonly employed in radar are the pencil beam (Fig. 
 STATE TRANSMITTER #OURTESY  OF  +ELVIN  (UGHES ,TD . ÓÓ°£n  2!$!2 (!.$"//+  4HE TRACKING PROBLEM IS COMPLICATED BY THE FACT THAT BASIC RADAR MEASUREMENTS  ARE MADE RELATIVE TO THE SHIPS MOTION  BUT THE DISPLAY MAY BE SET TO RELATIVE OR TRUE  MOTION )N ADDITION  TRUE MOTION CAN BE GROUND OR SEA STABILIZED 4ARGET VECTORS AND ASSOCIATED DATA BOXES CAN BE SHOWN IN TRUE OR RELATIVE MOTION  WHATEVER THE FRAME REFERENCE OF THE RADAR DISPLAY ! SHIPS ORIENTATION TO NORTH IS GIVEN BY A GYROCOM 
 Frush, I. Zawadzki, and A. Kilambi, “On the extraction of near-surface index of  refraction using radar phase measurements from ground targets,” J. 
 Bates: 1)oppier Radar Boast Design Innovations, Microwaves, vol. 13,  pp. 72-82. 
 1336. At large ranges acorrection must bemade fortheearth’s curvature. This can bedone with sufficient accuracy byadding atzterm tothesawtooth voltage, such aterm being obtainable byintegrating thesawtooth itself asinFig. 
 Unlike the targets previously discussed, which were assumed tobesmall tom. pared tothecross section ofthebeam and tobecharacterized byafixed radar cross section u,the ground isanextended, orcompound target. It consists ofamultitude ofsmall scattering orreflecting objects, many of F-, - ‘T ~ 0// ---—.—— FIG.2.2.—The problem oftheground-mapping antenna. 
 PLICATIONS 4HE OPTIONS RANGE FROM A FULLY ADAPTIVE SOLUTION ACROSS ALL AVAILABLE ANTENNA ELEMENTS AND ALL PULSES IN  A COHERENT PROCESSING INTERVAL #0)    TO REDUCED DEGREES OF  FREEDOM SOLUTIONS IN ORDER TO BE PRACTICAL 4HE FULLY ADAPTIVE SOLUTION ALSO ENCOUNTERS PROBLEMS IN THE REAL 
  +U  n  -ODERATE4!",%  !IR $ATA ,INKS. x°ÓÈ  2!$!2 (!.$"//+  WHERE DATALINK TRANSMISSION AND RECEPTION ARE INTERLEAVED WITH  OTHER MODES 4HE PRIN 
 At larger frequency offsets, significant  noise contributions can result from other components such as amplifiers in the STALO  signal path. Depending on the location of these amplifiers, they may either create  phase modulation that is common to both the receiver and exciter (correlated noise)  or add phase noise to only the receiver or exciter (uncorrelated noise). Uncorrelated  or uncommon noise is not subject to the range dependent factor described above so it  must be accounted for separately. 
 -/"  )NTRODUCTION 3EVERAL METHODS HAVE BEEN DESCRIBED TO COMPENSATE FOR ANTENNA  MOTION !LL THESE TECHNIQUES ARE APPLIED  IN THE RADAR DESIGN PH ASE FOR A SPECIFIC SET OF  OPERATIONAL PARAMETERS #ONTROLS USUALLY AUTOMATIC  ARE PROVIDED TO ADJUST WEIGHTS  FOR OPERATIONAL CONDITIONS AROUND THE DESIGN VALUE 4HE DEVELOPMENT OF DIGITAL RADAR TECHNOLOGY AND ECONOMICAL HIGH 
 CHIP MATCHING MAY BE NECESSARY TO MAXIMIZE POWER OUTPUT FOR A GIVEN DESIGN   'A!S IS A POOR THERMAL CONDUCTOR 0OWER &%4 DESIGN THAT ADDRESSES THERMAL MANAGEMENT IS REQUIRED !DEQUATE HEAT SINKING OF THE CHIP IS MANDATORY AND MAY BECOME A LIMITING FACTOR IN HIGH PERFORMANCE DESIGNS   #AREFUL ATTENTION MUST BE PAID TO UNPLANNED VOLTAGE STRESSES ON THE POWER AMPLIFIER  EITHER FROM TRANSIENT INDUCED EFFECTS OR LOAD IMPEDANCE VARIATIONS IN ORDER TO MAINTAIN THE DESIRED RELI 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 
 D K : "Radars. vol. 5, Radar Clutter." Artech House, Inc., Dedham. 
  %#237#23!.403 
 lmerar.:ia. vol. 23. 
 L.. and J. J. 
 FIELD DIVERGENCE AND WIND 
 (7)imposes arestriction onthe maximum gain GOwhich canbeachieved and hence onthemaximum range. Tosee this, letuscompute the average ofthe gain ofthe antenna over all directions, orl/47rJJG d~extended over thewhole sphere, where d~isthe element ofsolid angle. Bythe definition ofgain this integral must be equal to1.But first something must besaid about the shape ofthe antenna pattern intheother plane--that is,inaplane normal tothefan beam. 
 I.: Radar Horizon and Propagation Loss, Proc. IRE, vol. 45, pp. 
 The unfolding creates a vector of possible ranges for each valid detection by adding a  set of integers [0 … K] times the unambiguous range interval:  R Rc fK Runfold a mbiguous 0 = +2[ ]…  (4.9) where the unambiguous range interval = c/(2fR), with c = speed of light and fR = PRF.  The set of integers [0… K] are referred to as the range ambiguity numbers, with K deter - mined by the maximum range of interest ( K = CEIL[2 Rmax fR /c]). Range correlation  occurs when the unfolded detections are scanned and a correlation window is applied  across looks, as shown in Figure 4.17. 
 Radar instability produces predominantly phase modulation of the echoes, and the scanning antenna produces predominantly amplitude modulation; so the com- bined effect is the sum of the residue powers produced by each individually. 3.6 GAIN-CONTROLLED AMPLIFIERS Sensitivity Time Control (STC). The search radar detects echoes of widely differing amplitudes, typically so great that the dynamic range of any fixed-gain receiver will be exceeded. 
 4.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 B2 is small for a target in the main beam and large, 0 dB or so, for a target at the  sidelobe peaks. In the example shown, there is a 0.5 dB detectability loss due to  the guard blanking for targets in the main beam. Ideally, the guard antenna gain pattern exceeds that of the main antenna at all angles  in space (except for the main beam) to minimize detections through the sidelobes. 
 Sequential lobing, or lobe switching, was one of the first tracking-radar techniques to be  employed. Early applioations were in airborne-interception radar, where it provided direc-  tional information for homing on a target, and in ground-based antiaircraft fire-control radars.  It is not used as often in modern tracking-radar applications as some of the other techniques to  be described. 
 In all the above cases, the value of cross section to be substituted in the radar  equation is the average cross section <Ta". The signal-to-noise ratio needed to achieve a  specified probability of detection without exceeding a specified false-alarm probability can be  calculated for each model of target behavior. For purposes of comparison, the nonlluctuating  cross section will he called case 5. 
 The solid-state transmitter was put into produc - tion and installed in existing radars. It did the job it was supposed to do, but it is not  obvious that the solid-state transmitter had a net advantage over the tube transmitter.  The solid-state transmitter was supposed to occupy the same floor space as the vacuum  tube transmitter, but it occupied about the same floor space as the entire AN/SPS-40  radar, which used a vacuum tube. 
 It is  important to avoid receiver saturation, or overloading. A wide dynamic range is desired, and . 548 INTRODUCTION TO RADAR SYSTEMS  linear rather than square-law detectors are prderred. 
 To let GB-InSAR MIMO become a feasible and easily installable technology, IDS GeoRadar aimed to develop a system with a modular and integrated architecture. Modularity will help the installation procedure, allowing the sequential assembly of the various modules, rather than the whole system at the same time. Furthermore, the exploitation of highly integrated technologies such as microstrips and patch antennas, will lead to a cost reduction compared with other technologies such as coaxial cables and horn antennas [ 10]. 
 TER RETURNS  THE NOISE 
 This limited dynamic range, however, has the undesirable effect of causing additional clutter spectral broadening, and achievable clutter suppression is consequently reduced. In the MTD one or more high-resolution clutter maps are used to suppress the clutter residues, after doppler filtering, to the receiver noise level (or, alterna- tively, to increase the detection threshold above the level of the residues). This in turn eliminates the need to restrict the IF dynamic range, which can then be set to the maximum value supported by the A/D converters. 
  FOLLOWED IN THE FOOTSTEPS OF 4/0%8  FIGURATIVELY AND LITERALLY  !FTER THE LAUNCH OF *ASON 
 63, pp. 777-789,  May, 1975.  28. 
 109  11.8 Reduction of the Radar Backscattering Cross -Section ................................................. 110  11.8.1 Optimization of Shape and Style .......................................................................... 110  11.8.2 Covering with Radar absorbing material .............................................................. 
 TERM COHERENT CHANGE DETECTION MAY BE USED TO SEPARATE STATIONARY TARGETS FROM SLOW 
 1349, except that V,(V,ofFig. 13-49) isbiased somewhat below 200 volts, thereby introducing asmall correc- tion totake care ofinadequacies intheresponse ofthedeflection system. The potentiometer P1allows awide variation inthe sweep speed used, and Psadjusts thepattern toproper size. 
 When half-wavelength-spaced slots are fed in a  series fashion, the field inside the guide changes phase by 180° between elements. The phases of  every other slot therefore must be reversed to cause the radiated energy to be in phase. This is  accomplished in a slotted waveguide by altering the direction of tilts of adjacent elements. 
 We can see how the leading  marine radar systems have developed from basic equip-  ment. In airborne centimetric systems we can investi-  gate such devices as H2S. In navigational systems we can  investigate Gee, Oboe, G-H, and Loran, and a wide  range of beacon-direction, blind-landing, and height-  indicating equipments. 
 Thesensitivity ofaradarmaybevisuallydisplayed byusingthemeasurement ofreceiver noisetodisplaythenormalrangeringsonthePPIonlywithintherangeatwhichtheradar candetecttargetsreliably. Thisprovides theoperator withacontinuous andimmediate indication ofradarsensitivity. Whennoisejamming ispresent,theappearance ornonappear­ anceoftherangeringscanbe,made tobeafunction ofazimuth aswellasrange.. 
 Itshould not beforgotten that inthese latter pages wehave been wholly concerned with that obscure marginal region between strong signals and utterly undetectable signals. This margin isnot, after all, very broad. Aglance atTable 21, forinstance, sho~vs how very rapidly wdiminishes asthesignal becomes strong. 
 At  Lockheed’s fabled Skunk Works, he recognized the importance of bringing the RCS  design engineer into the inner-circle design team. The A-12 development contract was  awarded in 1959,69 and by early 1964 the A-12 was flying missions around the world. The influence of Johnson’s radar signature specialists is evident in Figure 14.30. 
 Following the analysis of Frank and Ruze,76 Figure 13.20 shows an aperture with  an even number of elements N, separated by distances s. All elements are excited with  ch13.indd   34 12/17/07   2:40:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 HALF THE RADAR WAVELENGTH   IE  h"RAGGv  SCATTER )N THE YEARS SINCE THESE EARLY MEASUREMENTS  THERE HAS BEEN CONSIDERABLE ACTIVITY IN THE FIELD OF (& RADAR AND (& CLUTTER    AND THE RESULTS CAN BE SUM 
 12.7.—Double-tuned i-famplifier. pacities associated with primary and secondary respectively. The bandwidth is ~=~ti 27rRPCP”(6) Hence thegain-bandwidth product is (7) Iftheloading isentirely onone side, either primary orsecondary, the above equations become (8) 11 a=%@RPCP’(9) Gx@=fi~. 
 4993–4999, 1986. 47. S. 
 InSees. 2.1to26weshall formulate and examine the basic relation between these quantities, which iscommonly known asthe “radar equation. ”Specifically, wewant toderive anexpression forthe peak radio-frequency signal power S,available atthe terminals ofthe radar antenna, which will involve measurable properties ofthe transmitting and receiving antenna system, the transmission path through space, and the target itself. 
 The fundamental theory of moving target indication (MTI) radar, as presented in the  previous editions of the Radar Handbook , has not materially changed. The performance  of MTI radar, however, has been greatly improved, due primarily to four advances:   (1) increased stability of radar subsystems such as transmitters, oscillators, and receivers;   (2) increased dynamic range of receivers and analog-to-digital converters (A/D);   (3) faster and more powerful digital processing; and (4) better awareness of the limita - tions, and therefore requisite solutions, of adapting MTI systems to the environment. These  four advances have made it practical to use sophisticated techniques that were considered,  and sometimes tried, many years ago but were impractical to implement. 
 ING ELEMENTS 42 MODULES FITTING BEHIND EACH ELEMENT ARE CONSTRAINED BY THESE SPACINGS  "  $!%  
 It was noted earlier that summaries of clutter measurements made before about 1970 may be found in several of the standard reference books on radar23 and radar clutter.1 Among the programs of this period, the most ambitious was that pursued in the late 1960s at the Naval Research Laboratory (NRL),21 in which an airborne four-frequency radar (4FR), operating with both horizontal and vertical polarizations at UHF (428 MHz), L band (1228 MHz), C band (4455 MHz), and X band (8910 MHz), made clutter measurements upwind, downwind, and crosswind in winds from 5 to 50 kn for grazing angles between 5 and 90°. The system was calibrated against standard metal spheres, and wind speeds and waveheights were recorded in the measurement areas from instrumented ships. Typically, samples of cr° for a given set of radar and environmental parameters are scattered over a wide range of values and in the NRL experiments were or- ganized into probability distribution functions of the type shown in Fig. 
 FERENT WEIGHTING CONSTANTS ARE REQUIRED FOR EACH PULSE PAIR 4HE VALUES OF  K FOR THE  QUADRATURE CORRECTION OF THE FIRST PULSE PAIR   K FOR THE QUADRATURE CORRECTION FOR    THE SECOND PULSE PAIR   L FOR THE IN 
 34. Mavroides. W. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 Daytime absorption increases for a given frequency because of higher D-layer densi - ties, but this is compensated by access to higher operating frequencies. 
 APERTURE RADAR SYSTEM v  )%%%  *OURNAL  OF  /CEANIC  %NGINEERING  VOL /% 
 Although tracking accuracies are less than can be achieved in a single-target track, multiple targets can be tracked simultaneously over a large volume in space. A second method of multiple-target tracking, pause-while-scan, particularly applicable to electronic scan antennas, is to scan in a normal search pattern, pause on each search detection, and enter a single-target track mode for a brief period. The advantage is that the resulting range, angle, and doppler measure- ments are more accurate than those made with a scanning antenna, but the time to search a volume in space is increased. 
 The clutter-rejection band of the doppler filter must be wide  enough to accommodate this spread. In the multiple-filter bank, removal of those filtc~s in the  vicinity of the RF or IF carrier removes the stationary-target signals.  Sign of the radial velocity. 
 As has been mentioned, Faraday ro- tation will ensure periodic illumination with the most favorable polarization. Figure 24.5 gives the vertical-polarization RCS of a rod and a hemisphere sticking out of a perfectly conducting surface. With these canonical shapes an estimate of RCS can be made for surface craft. 
 -Ê"Ê-, 7HEN WE REFER TO 3!2  WE USUALLY MEAN  FOCUSED 3!2 THE TERM INDICATES THAT THE  PHASE INFORMATION HAS BEEN OPTIMALLY PROCESSED TO PRODUCE RESOLUTION COMPARABLE TO THE THEORETICAL LIMIT )N THE DEVELOPMENT OF 3!2  SEVERAL INTERESTING TECHNIQUES .   39.4(%4)# !0%2452% 2!$!2   £Ç°Î PRECEDED THE DEVELOPMENT OF FOCUSED 3!2 4HESE TECHNIQUES ARE DISCUSSED IN ORDER OF  PROGRESSIVELY FINER RESOLUTION 0RECURSORS TO &OCUSED 3!2 3IDE 
 Electronic Progress, vol. 17, no. 2,  pp. 
 LAW SIGNAL DETECTION  SAMPLES OF THE MEAN POWER  0R OF THE PROCESS ARE EXPO 
   2!$!2 #2/33 3%#4)/.   £{°£Î %XAMPLES OF 2#3 PATTERNS FOR AIRCRAFT ARE SHOWN IN &IGURES  AND  4HE  " 
 30 
 The antennas rotate about a\crtical axis at2or4rpm, together with their respective transmitters and common modulator. There isnoele- S Lineararrays 7_. H?usings forelectronic uni~ I FIG. 
 Then the Eureka  beacon begins transmitting pulses which show up on  the CRT carried in the navigator’s cockpit. Under war  conditions beacons which respond only to certain codes,  or to certain types of interrogator, have their obvious  uses, as security is improved. Such a radar system does  not broadcast continuously, but is interested only m  some minute fractions of time—for instance, 1§ mucro-  seconds within each three-millisecond period of time. 
 QUENCY ON A PULSE 
 N. Davies, and M. F. 
 24, 1982, issued Oct. 8. 1982. 
 £È°Îä  2!$!2 (!.$"//+  BUT NEARLY ALL MEASUREMENTS FIT SUCH A MODEL CLOSELY  AND THE MODEL APPROXIMATES  MOST THEORETICAL CURVES WELL OVER THE RELEVANT REGIONS 4HIS SIMPLE RESULT MEANS THAT SIMPLE CLUTTER MODELS MAY BE DEVELOPED AND USED  ALTHOUGH MORE COMPLEX MODELS MAY BE NECESSARY FOR SOME REMOTE 
 Thisillustrates the necessity forflexiblemanagement oftheradar.Theionosphere mustbesensedandtheparam­ etersoftheradaradjusted tooptimum operation. Withproperradardesignandmanage­ mentitshouldbepossible toachieveapropagation pathreliability comparable tothatofa microwave radar.Thisrequires alargefrequency rangeofoperation, highpowertoovercome propagation losses,anddiagnostics oftheionospheric conditions todetermine properradar parameters. Example capabilities. 
 (a)  Dispersive delay line with dispersion  designed into one transducer; (h)  dispersion in both transducers, and  (c) a reflective array compressor  (RAC). (From Maines and Paige,"  courtesy of Proc. 1 EEE.)  comb fingers, or electrodes, of the IDT are spaced one-half the wavelength of the acoustic  signal propagating along the SAW materiaLZ2 Thus the frequency response of the delay line  depends on the periodicity of the electrode spacings. 
 314. Sensors 2019 ,19, 1529 (a)ȱ (b)ȱ (c)ȱ (d)ȱ µPD[Figure 2. Simulated current ﬁelds of vortex based on the Burgers-Rott model. 
 A. Oliner and G. H. 
 The term effective number of bits  is often used  to state the true performance of an A/D converter and has been stated in the literature11  in terms of SINAD and SNR, as given below. Consequently, it is important to differ - entiate between definitions when using this term.  Neff = [SINAD (dB) − 1.76 ] / 6.02 (6.38)  Neff = [SNR(dB) − 1.76 ] / 6.02 (6.39) Two Tone Intermodulation Distortion (IMD). 
 3.5  3.3 Bandwidth Considerations  ......................................  3.5  Definition  ...........................................................  3.5 Important Characteristics  ................................... 
 13.26) because  phase rather than time delay is adjusted. These two changes in beam-pointing direction  may add or subtract, depending on the direction in which the beam has been scanned.  The worst case will be considered here. 
 DOR CHAFF  A CELL 
 In order to select the best type of antenna for a radar system, the system designer should have a clear understand- ing of the basic performance features of the wide variety of antenna types from which he or she must choose.1 This includes the choice between reflector anten- nas, covered in this chapter, and phased arrays, covered in Chap. 7. Another al- ternative is a reflector fed by a phased array. 
 TER CELL 0ROVIDED THE WIND SPEED IS GREATER THAN ABOUT  L KT WITH K IN METERS  AND  THE SEA IS FULLY DEVELOPED  THE CLUTTER CROSS SECTION  R   IS ABOUT n D" AND IS RELA 
   PP n  *ULY   2 # *OHNSON  ( ! %CKER  AND 2 ! -OORE  h#OMPACT RANGE TECHNIQUES AND MEASUREMENTS v  )%%% 4RANS  VOL !0 
 J. Haines, L.-L. Fu, and P. 
 This entire staff agreed toremain atwork at MIT forsixmonths ormore after thework oftheRadiation Laboratory was complete. These volumes stand asamonument tothis group. These volumes serve asamemorial tothe unnamed hundreds and thousands ofother scientists, engineers, and others who actually carried ontheresearch, development, and engineering work theresults ofwhich areherein described. 
 The illumination was no longer continuous, and the missile would thus have to operate in a sampled-data mode, extracting information during the time that its target was illuminated (dwell time) and then holding the information until the next sample. The illumination waveform could be CW during the dwell time (inter- rupted or keyed CW), or PD could be employed with or without pulse compres- sion. For sampled-data operation, the primary difference is in the doppler acquisi- tion scheme. 
 J. Anderson, “The doppler structure of diffusely-scattered skywave radar echoes,” Proc. Int. 
 itisfoundthattheuseofacriterion whichmaximizes theclutterattenuation (ratio ofinputclutterpowertotheoutputclutterpower)isalsowellapproximated byatransversal filterwithbinomial weightsofalternating signwhentheclutterspectrum canberepresented hyagaussian function whosespectral widthissmallcompared tothepulserepetition frequency.7 Thusthedelaylinecancellers withresponse sin"1tfdTare"optimum" inthesense thattheyapproximate thefilterswhichmaximize theaverage signal-to-clutter ratioor theaverageclutterattentuation. Italsoapproximates thefilterwhichmaximizes theprobabil­ ityofdetection foratargetatthemidband doppler frequency oritsharmonics.6 Inspiteofthefactthatsuchfiltersare"optimum" inseveralsensesasmentioned above, theydonotnecessarily havecharacteristics thatarealwaysdesirable foranMTIfilter.The notchesatdc,attheprf,andtheharmonics oftheprfareincreasingly broadwithincreasing number ofdelaylines.Although addeddelaylinesreducetheclutter,theyalsoreducethe numberofmovingtargetsdetected becauseofthenarrowing ofthepassband. Forexample, if the-10dBresponse ofthefiltercharacteristic istakenasthethreshold fordetection andif thetargetsaredistributed uniformly acrossthedoppler frequency band,20percentofall targetswillberejectedbyatwo-pulse canceler (singledelay-line canceler), 38percentwillbe rejected byathree-pulse canceler (doublecanceler), and48percentbyafour-pulse canceler (triplecanceler). 
 Prime power consumption in average  traffic can be less than 1 watt. The modulation on the response signal of a racon paints a Morse code image on the  radar display. The code identifies a particular AtoN and appears in the radial direction,  conventionally commencing with a dash. 
 Third, the TEC deviations between ISR and PolSAR are within 1 TECU. This illustrates the feasibility of measuring TEC with PolSAR. For a better understanding of the performance of PolSAR, we also present here the TECs obtained from GNSS. 
 Kimbrell, C. E. Caldwell, and G. 
 LINE 
 Processor Implementations. In nondoppler radars it is common to use log- video receivers along with sensitivity time control (STC) for inverse r2 correction in order to achieve the widest dynamic range possible. For signal power estimation, the log-video signal is digitized and averaged or, in the most rudimentary of systems, may be used to modulate an analog PPI or other type of radarscope directly. 
 INTERFERENCE 
 PERIODIC ANTENNAS  VERTICAL PLANAR ARRAYS OF HORIZONTAL DIPOLES  STACKED 9AGI ANTENNAS  ELEVATED RHOMBIC ELEMENTS  LINEAR ARRAYS  OF TILTED MONOPOLES   AND A TWO 
 :n Fvanzia. W. J.: Faster, Lighter 3-D Radars in Sight for Tactical Warfare. 
 SIZE DISTRI 
 If there is uncertainty about whether or not the noise is Rayleigh-distributed, it is better to threshold individual pulses and use a binary integrator as shown in Fig. 8.13. This detector is tolerant of variations in the noise density because by setting K to yield a 1 with probability 0.1, a Pfa ~ 10~6 can be obtained by using a 7-out-of-9 detector. 
 LAYS  VERTICAL INCIDENCE SOUNDINGS RECORDED AT THE SAME TIME OF DAY FOR A MONTH        
 The efficiency is 40 to 45  percent. (Cotrrfesy Vnrinrt Associnres, Ilrc.,  Beverly, MA. )  reliability than conventional magnetrons. 
 Figure 4. Simulated SAR image of an eddy. The size of the scene is 20 km ×20 km. 
 ALTERNATE 
 3.53  Interference region 2.43  Interferometer height finder 20.6  Inverse Cassegrain 18.32 19.34  Inverse receiver for semiactive guidance 19.12  Inverse synthetic aperture radar (ISAR) 21.21  Ionograms    24.17  Ionosphere 24.15  Isodops in airborne radar 12.15  J  Jamming      9.4  radar equation for 1.9 9.29  Jaumann absorber 11.48  JETDS nomenclature 1.18  K  K band       1.14 1.17  Kalman filter 8.28 8.36 8.43  Klystron     4.14 4.19  L  L band       1.14 1.16  This page has been reformatted by Knovel to provide easier navigation. I.21  Index terms  Links   Lambert's law 12.7 13.16 13.34  Laser frequencies 1.18  Lens-effect loss 2.52  Letter-bands for radar 1.14  Likelihood ratio 8.2  Limiter      3.30  Limiting in MTI radar 15.41  Line-type modulators 4.33  Linear array 7.10  Linear-beam tubes 4.12  Linear-FM pulse compression 10.4  delay lines for 10.12  Stretch processor 10.8  Taylor weighting in 10.30  Lobe switching 18.3  in height finding 20.2  Local oscillator 3.11  Log-CFAR     8.18  Logarithmic amplifier 3.28  Logarithmic detector 3.26  Logarithmic devices 3.25  Logarithmic receiver for ECCM 9.18  Loss:  in CFAR      3.47 3.53 8.13  filter mismatch 15.14  Loss factors in radar equation 2.46  Low-angle height finding 20.36  Low-angle tracking 18.46 18.54  Low-sidelobe antennas 7.37 9.24  This page has been reformatted by Knovel to provide easier navigation. I.22  Index terms  Links   M  Madre OTH radar 24.5  Magnetrons 4.5  Main-beam clutter in pulse doppler radar 17.16  Man, radar cross section of 11.16  Man-made noise 24.13  Maneuvering gate in automatic tracker 8.31  Marcum universal curve 17.37  Martello radar 20.8  Matched filter  approximations to 3.21  in pulse compression 10.1  Maximal-length sequences 10.19  Maximum-entropy method 15.64  Maximum-likelihood tracker 8.38  Medium-PRF ranging 17.25  Mesocyclones 23.20  Metal space-frame radomes 6.47  Meteorological radar:  airborne     23.26  ambiguities in 23.10  applications of 23.17  attenuation in 23.5  dBZ in       23.3  design considerations for 23.5  doppler      23.1 23.13 23.15   23.18  doppler spectrum of 23.14  fog attenuation in 23.10  ground clutter effects in 23.11  hail attenuation in 23.8  hail detection with 23.22  This page has been reformatted by Knovel to provide easier navigation. 
 97.Blackwell. F.oandE.W.Houghton: RadarTracking andIdentification ofWildDuckDuringthe Autumn Migration. Prot.'.WorldCOllt:OilBirdHazards 10Aircraft. 
 Further, the HF signal environment  includes (one-way) transmissions from powerful radio stations around the world, as  discussed in the previous section. Imperfections in the receiver result in some of this  ch20.indd   46 12/20/07   1:16:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Each line is a three-sided square trough with an insulated conductor passing down  the middle. A moving arm makes contact with each circular assembly. The arms are rotated to  produce a continuous and uniform variation of phase across the elements of the array. 
 19.2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 precipitation measurement, for detecting hail,15 and for discriminating ice particles (snow)  from water (rain).16 Furthermore, ground-based research radars can now measure atmo - spheric moisture in the surface boundary layer.17 Airborne research radars provide many  of these same capabilities with increased coverage and greater mobility.18 This variety of  applications in both research and operations illustrates the vitality of meteorological radar  technology and its evolution. This chapter is intended to introduce the reader to meteorological radar, particularly  those system characteristics that are unique to meteorological applications. In this  regard, it should be noted that most meteorological radars appear similar to radars used  for other purposes. 
 Range determinations made in this way require that the display pattern bemoved ascoincidence between the echo and the marker isestablished. Ifthis isundesira- ble,themarker-pulse delay canalso bemade variable and the two added, either bytheoperator orby anarrangement for mechanically summing the settings ofthe two control knobs. This method is more convenient than separating the delay and the measuring cir-~ Nlayed sweep higgw Trigger1 I I Delayed triggerI 1 I Delayed sweepA Marker pulseI I I Fro. 
 FACE RAINFALL RATE   H IS THE HEIGHT ABOVE THE %ARTHS SURFACE  AND  D IS A CONSTANT  EQUAL  TO ABOUT  #ONVECTIVE PRECIPITATION  HOWEVER  SHOWS A QUITE DIFFERENT NATURE &OR  EXAMPLE  THE PRESENCE OF  VIRGA PRECIPITATION ALOFT BUT EVAPORATING BEFORE REACHING  THE SURFACE  ASSOCIATED WITH SO MANY SHOWER 
 At each range interval the detector integrates 11 pulses, where n is the number  TRACKING RADAR183 Themonopulseradaristhemorecomplex ofthetwo.Threeseparate receivers are necessary toderivetheerrorsignalintwoorthogonal angularcoordinates. Onlyonereceiver isneededintheconical-scan radar.(Therearecertainmonopulse implementations thatcan useeitheroneortworeceivers. butatsomesacrifice inperformance.) Sincethemonopulse radarcompares theamplitudes ofsignalsreceived inthreeseparate channels, itisimportant thatthegainandphaseshiftthrough thesechannels beidentical. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 25.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 a general NCO will be in Section 25.3. 
 Electronics, 1958, pp. 279-285.  13. 
 MATRIX FORM AS   V% %% %(2 62(" 6" REC §©¶¸§ ©¨¶ ¸·    4HIS IS THE STARTING POINT FOR 3!2 QUADRATURE POLARIMETRY %SSENTIALLY  A QUAD 
 A large  f/D requires a greater mechanical structure because the feeds are bigger and must be supported  farther from the lens. The mechanical support of a lens is usually more of a problem than with  a reflector.  The wide-angle scanning capability of a lens would be of interest in radar as a competitor  for a phased array if there were available a practical means for electronically switching the  transmitter and receiver among fixed feeds so as to achieve a rapidly scanning beam. 
 GRAZING MEASUREMENTS  ALSO COLLECTED EXTENSIVE hGROUND 
 Azimuth ambiguities, especially from point targets,  have the same doppler FM rate as scatterers within the main beam, and so their focus  is preserved through the processor. In the range direction, one of the consequences of having many pulses in flight at  once is that there are echoes from several different ranges that arrive back at the radar at  the same relative delay within the range gate as the reflections from the intended swath.  If these extra echoes are sufficiently strong, the resulting image artifacts are range ambi - guities. 
 16, pp. 6-1 1, February, 1959.  114. 
 Moore, “Evaluation and comparison of dominant backscatter - ing sources at 10 GHz in two treatments of tall-grass prairie,” Remote Sensing Environ. , vol. 22,   pp. 
 IIIA, p. 627, 1946.  31. 
 It should be noted that the meteorological conditions necessary for a surface-based  duct are the same as those for an elevated duct. In fact, a surface-based duct may slope  upward to become an elevated duct as warm, dry continental air glides over cool, moist  marine air. The tradewind inversion may also intensify, thereby turning an elevated  duct into a surface-based duct. 
 BAND INTERFERING SIGNALS 4HE ,.&% CONSISTS OF AN 2& AMPLIFIER TYPICALLY GIVING ABOUT  D" GAIN  AND A BALANCED MIXER  LOCAL OSCILLATOR  AND )& HEAD AMPLIFIER  4HESE ARE NORMALLY SUPPLIED TO THE RADAR MANUFACTURER BY SPECIALIST COMPANIES AS A  COMPLETE SUBUNIT 4HE OVERALL SYSTEM NOISE FIGURE IS TYPICALLY  TO  D"  BUT LOWER FIGURES ARE ACHIEVABLE 4HE FREQUENCY OF THE LOCAL OSCILLATOR IS GENERALLY DRIVEN BY A CONTROL SIGNAL  DERIVED FROM WITHIN THE )& AMPLIFIER )T INCLUDES FACILITIES FOR MANUAL FREQUENCY CONTROL BY THE OPERATOR 4HE LATTER CAN BE USEFUL  FOR INSTANCE  WHEN LOOK 
 The three-pulse canceler shown in Fig. 4.9b is an example of a transversal  filter. Its general form with N pulses and N -1 delay lines is shown in Fig. 
 640-644, July, 1968.  55. Grasso, G., and P. 
 Sector scan is,asitsname implies, anarrangement forcausing theantenna toscan back and forth across adesired sector, sometimes one centered dead ahead ofthe aircraft, and sometimes one that isadjustable atthe will ofthe operator. The indicator provisions forhoming areofeither oftwo types: thesetmay have atype Bdisplay, which facilitates homing because thecondition foraninterception course isthat the target signal approach down avertical line ofconstant azimuth, oritmay have an open-center PPI. Inthelatter, thetarget follows along aradius asthe range isclosed onaninterception course; the open center reduces the crowding ofsignals atshort ranges and makes homing easier. 
 The result is shown in Fig. 10. With the  exception of the anomalies that occur during the full sun  periods (which reflect calibrate mode artifacts), the drift  has been negligible, i.e., less than I centimeter. 
 ,;,·;·: ,:v~;J.:i:,};H~t:it'!F,  Figure 6.15 AN/TPS-59 L-hand radar. The 30 ft by 15 ft antenna consists of 54 rows of24 elements each.  Fach of the 54 rows contains ils own transceiver with twenty-two 50-W modules along with phase shifter. 
 no. 105, pp. 274-279, 1973. 
 LINE 
 y(t)  Multiplier  q(t-Tnl Low-poss  filter  (integrator) Output  Figure 11.2 Receiver for measuring range (lime delay)  using a gating signal g(t -TR), where TR is the estimate  of the true time delay. Note the similarity to the cross­ correlation receiver of Fig. 10.3. 
 Thesepeakscause ambiguities. Thetotalvolumerepresented bytheshadedareasoftheambiguity diagram for theperiodic waveform approximates thetotalvolumeoftheambiguity diagram ofthesingle pulse,assuming thattheenergyofthetwowaveforms arethesame.Thisfollowsfromthe relationship expressed byEq.(11.54).Inpractice, theradardesigner attempts toselectthe pulse-repetition periodTpsothatalltargetsofinterestoccuronlyinthevicinityofthecentral peak,allotherpeaksbeingfarremoved fromtheregionoccupied bythetargets.Theperiodic­ pulsewaveform isagoodonefromthepointofviewofaccuracy iftheradarapplication is. l:X I HAC'I ION 01' INI'URMA'I ION AND WAVE1:ORM DESIGN 417  Figure 11.11 (a) Pulse train con-  sisting of five pulses; (b) ambi-  (b) guity diagram for (a). 
 ¤ ¦¥³ µ´    WHERE K  IS THE WAVELENGTH   FR IS THE AVERAGE PULSE REPETITION FREQUENCY  AND  RV IS THE  RMS VELOCITY SPREAD OF SCATTERING ELEMENTS 4HIS IS PLOTTED IN &IGURE  FOR RAIN AND  FOR WOODED HILLS WITH  A  KNOT WIND 4HIS  LIMITATION ON THE -4 ) IMPROVEMENT FACTOR  IS INDEPENDENT OF THE TYPE OF CANCELER EMPLOYED 4IME 
 If . 554 INTRODUCTION TO RADAR SYSTEMS  ---------- ob -------··-------1  Figure 14.11 Geometry of a bistatic radar. ,)  many separated receivers are employed with one transmitter, the radar system is called multi­ slatic. 
 The current multi-angle SAR includes spotlight SAR [ 4], wide azimuth beam SAR [ 5] and multiple ﬂight paths SAR [ 6] In the spotlight SAR, the antenna is steered to increase extend the synthetic time and to observe targets from different angles. In this mode, the azimuth bandwidth of the signal may greater than the PRF, which causes spectrum ambiguity and makes signal processing more complicated [ 4]. The spotlight SAR expands observation angle but reduces the imaging scope. 
 T.. and T. F. 
 COMPATIBLE USER 
 Many fan-beam air-sea~ch radars  employ this type of pattern. A constant echo signal with range, however, is probably not as  important an application of the cosecant-squared pattern as is achieving the desired elevation  coverage in an efficient manner. Shaping of the beam is desirable since the needed range at  high angles is less that at low angles; hence, the antenna gain as a function of elevation angle  can be tailored accordingly. 
 The receiver operates from a separate antenna (electrically isolated). The  output of the receiver is detected, averaged, and digitally recorded. Its sensitivity must  be checked by use of a calibration source. 
 ICE  HAD BEEN DISCOVERED AT THE -OON PRECIPITATED WIDE INTEREST 7HEN INDEPENDENT ANALY 
 Beam-limited techniques, of which laser altimeters are extreme examples,  circumvent these problems, but may imply their own set of disadvantages. A major potential application of radar altimetry is to monitor the height of extensive  ice sheets, as found in Greenland or Antarctica. Approximately 95% of these land-ice  surfaces have slopes less than ∼3°, which, although small, is sufficient to trick a con - ventional altimeter into very large height errors. 
 20. New Satellite to Measure Ocean Surface Topography and Sea State, NASA News Re- lease 75-88, Washington, Mar. 31, 1975. 
 5. Conclusions A multi-angle SAR imaging system is proposed in this paper using multi-beamforming. When using an ultrahigh speed platform, the main issue is an increase in Doppler bandwidth in the signal. 
      . 
 940-971, November.  1946.  3. 
 MAPPING PROCESSES !LL OF THIS IS ATTEMPTING TO CREATE A CONSTANT FALSE ALARM RATE ACROSS THE RADAR DISPLAY 3INCE THE RADAR IS SITED ON A MOV 
 Onthe other hand, c-w methods involve somewhat simpler terminal equipment than dothepuke methods. They arealso much lesssuscepti- bletopulse interference, which isthetype most likely tobemet with at most ofthe radio frequencies involved. Comparison ofSpecijic Methods.—The specific synchronization methods that have bee~ most thoroughly tested are— 1.The conveying ofsine and cosine bypulses. 
 Asimple way ofdoing this istouseanother supersonic delay line asthetiming element inthetrigger ~Trigger tosystem 15Mclsec resonantTrigger *15Me/see+ circuitdelayline amplifier 1t t Blocking Video. +Detectoroscillator amplifier FIG. 16,12.—Trigger generator. 
 A. R. Lopez and W. 
 As applied to  arrays, the various stages of dynamic programming involve the selection of the spacings of  each element or pair of symmetrically placed elements. The application of dynamic program-  ming has been successfully applied to the design of one dimensional (linear) unequally spaced  array. Although the computations requireti are far less than for total enumeration, there is a  practical limit to the number of elements in the array that can be treated by this method. 
 Dependence on Wind Direction. In several of the experiments referenced above, the dependence of sea backscatter on angle relative to the wind direction was found by recording the radar return from a spot on the surface while flying around it in a circle. Figure 13.1Oa and b gives an example of this behavior for grazing angles of about 45° and wind speeds close to 15 kn.29 The figures contain results obtained independently by three different groups. 
 Intheautumn of1922A.H.TaylorandL.C.YoungoftheNavalResearch Laboratory detected awooden shipusingaCWwave-interference radarwithseparated receiver and transmitter. Thewavelength was5m.Aproposal wassubmitted forfurtherworkbutwasnot accepted. Thefirstapplication ofthepulsetechnique tothemeasurement ofdistance wasinthe basicscientific investigation byBreitandTuvein1925formeasuring theheightofthe ionosphere.4.16However, morethanadecadewastoelapsebeforethedetection ofaircraftby pulseradarwasdemonstrated. 
 BASED EXPERIMENTAL MIRROR ANTENNA SYSTEM CONCEPT WAS  DEVELOPED WITH DUAL 
 Delay line  Mixer  Figure 8.20 Huggins phase shift­ ing applied to a linear array feed. TIIE ELECTRONICALLY STEERED PHASED ARRAY ANTENNA IN RADAR 305  line, as illustrated in Fig. 8.20, can be utilized to obtain a series fed array. 
 -(Z GRANULARITY INSTEAD OF THE  -(Z USED  THE 3.2 WOULD BE REDUCED BY ONLY A DECIBEL OR SO &)'52%   4HE NUMBERS IN THIS FIGURE SHOW THE 3.2 IN D" AS A FUNCTION OF FREQUENCY AND RANGE IN  THE FORM OF AN OBLIQUE SOUNDING  AS IN &IGURE   BUT FOR  '-4 NIGHT  3EE THE TEXT FOR A DESCRIPTION  OF RADAR PARAMETERS. Óä°ÈÓ  2!$!2 (!.$"//+  4HE PERFORMANCE ESTIMATION CHARTS THAT FOLLOW COME FROM ANALYSES AS DESCRIBED  ABOVE !FTER PERFORMING OBLIQUE SOUNDING CALCULATIONS  A RANGE 
 Mitchell, R. L., and J. F. 
 as the  performance of some radars can be stongly affected by the presence of meteorological particles  (hydrometeors). In general, radars at the lower frequencies are not bothered by meteorological  or weather effects, but at the higher frequencies, weather echoes may be quite strong and mask  the desired target signals just as any other unwanted clutter signal.  Whether the radar detection of meteorological particles such as rain, snow, or hail is a  blessing or a curse depends upon one's point of view. 
 POLARIZED HIGH 
 Applications.  Pulse doppler is applied principally to radar systems requiring  the detection of moving targets in a severe clutter environment. Table 4.1 lists typi - cal applications and requirements.4–12 This chapter will deal principally with airborne  applications, although the basic principles can also be applied to the surface-based  case. 
 11, pp. 44-48, August.  1972. 
 However, the targets that survive can be effectively tracked because  the probability of false alarm has been maintained at sufficiently low levels. Without  CFAR and appropriate threshold adjustments, perhaps no targets will be tracked due to  the very large number of false peaks (detections on the jammer), making it through to  saturate the tracker. Conventional CFAR is not really removing the interference: it is  just “hiding” it from the radar operator. 
 H. E. King, F. 
 Any use is subject to the Terms of Use as given at the website. Radar Cross Section.  RADAR CROSS SECTION  14.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 The method of moments has become a powerful tool in the prediction and analysis  of electromagnetic scattering, with applications for antenna design as well as RCS  prediction. This method has three limitations, however. 
 , vol. 83,   pp. 1313–1316, 2002. 
 DELAY CANCELER WILL PERFECTLY CANCEL A LINEAR WAVEFORM   6T    C   AT  IF  IT IS SAMPLED AT EQUAL TIME INTERVALS INDEPENDENT OF THE CONSTANT  C OR THE SLOPE  A  !DDITIONAL DELAY CANCELERS PERFECTLY CANCEL ADDITIONAL WAVEFORM DERIVATIVES EG  A THREE 
 THIRD OF THE PRIME POWER OF A SILICON 
 1, pt. 3, 1957, pp. 101–110. 
 Varactor frequency multipliers, however, generally' have attenuation less than their  frequency-mitltiplication ratio so that a transistor at some lower frequency followed by a  varactor multiplier has sometimes been employed to obtain power at the higher microwave  frequencies. In one experimental design,30 X-band power was obtained by an S-band transistor  followed by a four-times multiplier to obtain 1 watt of peak power at X band with a 0.05 duty  cycle.  "5  Bulk-effect and avalanche diodes. 
 Vertical electron content from ionograms in real time. Radio Sci. 2001 ,36, 335–342. 
 The relative  phase between the direct and reflected rays can be different in the presence of the duct, and . PROPAGATION OF RADAR WAVES 455  focusing can change the relative amplitudes of the two components. The focusing effect can  even cause the amplitude of the surface-reflected ray to sometimes exceed that of the direct  ray.-'8 The e!Tect of the duct on the line-of-sight propagation is to reduce the angle of the lowest  lobe. 
 A. S.: "Guidance," pp. 408-413, D. 
 Thewavelength &1,25cm. (Courtesv OJBell Telephone Laboratories.) frequent y. Itisinteresting tonote that this ‘resonant system results in anoperating orr-mode which lies intermediate infrequency between other modes while, forstrapped tubes, the r-mode has the lowest fre- quency. 
 Ordinarily the quadrant cover isonand nohigh voltages are exposed. 426 R-FCOMPONENTS [SEC.11.12 when the lidofthe whole r-fhead isoff. The pulse compartment also contains the magnetron cathode-heating transformer and the necessary bypass condensers toprovide apulse path toground inthe metering circuit. 
 PPI; P7screen; decay time about 7sec I-fbandwidth .................@=l.2Mc/sec Video bandwidth .,.... ., b=5Me/see Pulse duration ................T=l.Oxee Pulse repetition frequency. 320pps )Hence about 50pulses ononepoint Scan rate..................,., 6rpm target perscan, with negligible scan- Beamwidth ...................0=6° to-scan storage. 
 53.Nelson,T.M.•andH.Goldie: FastActingX-Band Receiver Protector UsingVaractors,lEEE MIT Symposium Digest,pp.176-177, 1974.AlsoWestinghouse Systems Development Division (Baltimore. Md.)reportDS('-973I bythesameauthorstitled,FastActingVaractors forSub-Nanosecond Power Limiting inReceiver Protectors (nodate). 54.Hirsch,R.B.:PlainTalkonLogAmps,Microwaves, vol.17,pp.40-44,March,1978.(TheefTect ofIF gainonthereceiverdynamic rangewasalsoindicated byWarrenD.White,oneofthereviewers ofthe revisedmanuscript ofthisbook.). 
 Now this issubstantially what many radar indicators do;itissonearly what they do, infact, that quantitative conclusions drawn from astudy of the ideal process outlined are ofpractical significance and are surpris- ingly well borne out byactual observations. Therefore, wewant to inquire more carefully into thesimple averaging orintegration process. IWe usetheterm “sweep” tomean oneentire interval between successive pulse transmissions. 
 Two important factors have contributed to this. First, it makes  the antenna more expensive, exacerbated by IMO’s requirements that 9 GHz radars  must be at least switchable to horizontal polarization when searching for survival craft  fitted with Search and Rescue Transponders (see Section 22.8). Second, by use of  small range cells and by implementing conventional signal differentiation techniques,  modern radars, particularly at 3 GHz, give reasonable performance in most commonly  experienced precipitation clutter. 
 and R. L. Olsen: Calculation of Radiowave Attenuation Due to Rain at Frequencies  i~p lo 1 OW Ci Hz. 
 FACE AND NOT FROM DIRECT MEASUREMENTS USING THE TRADITIONAL RADIOSONDE  ROCKETSONDE  OR MICROWAVE REFRACTOMETER 7ITH THE ADVENT OF NEWER  HIGH 
 REDUNDANT PROCESSOR COMPLEX %ACH MICROWAVE ANDOR 2& APERTURE MAY HAVE SOME EMBEDDED SIGNAL CONDITIONING  BUT THEN MAY BE MULTIPLEXED TO STANDARDIZED COMMON DESIGN 2&  FILTER  FREQUENCY REF 
 With the periphery of the PPI representinga distance of 20 miles from the center of the PPI at the 20-mile range scalesetting, the time required for the electron beam to move radially from thecenter to the periphery is the same as the time required for the transmitted pulse to travel to a target at 20 miles and return to the antenna as a reﬂectedecho or the time to travel 40 miles in this case. It follows that a point on thesweep or time base halfway between the center of the PPI and its peripheryFigure 1.18 - The sweep on the plan position indicator. 23represents a distance of 10 miles from the center of the PPI. 
 Sauermann and P. C. Waterman, “Scattering modeling: Investigation of scattering by rough  surfaces,” MITRE Corporation, Rept. 
 AMPLITUDE FLUCTUATION 4HERE IS A DEGREE OF CORRELATION BETWEEN THE ANGLE 
 After the bunched  electrons deliver their RF power to the output, the spent electrons are removed by the  collector  electrode. An axial magnetic field is employed to counteract the mutual repulsion of the  electrons that form the electron beam. The magnetic field confines the electrons  to a relatively long, thin beam and prevents them from dispersing. 
 The third requirement will be met by ASV equipment which enables the aircraft to position itself by, and home on to, secure coded beacons from long ranges, together with the ability to receive directional indications from special beacons with suf ﬁcient accuracy to enable a beam approach to be executed. ASV equipment should give full display of information to the operator and incorporate the maximum of automatic control. A simple form of indicator should,in addition, be provided for the pilot, which he may, or may not, use at his own convenience. 
 Frequency. I'lie plot of 0" vs. gra7ing angle for various freqilencies (Fig. 
 9.6, but it has less bandwidth.  TR tubes. The TR tube is a gas-discharge device designed lo break down and ionize quickly at  the onset of high RF power, and to deionize quickly once the power is removed. 
 Their pulse-power output ranges from afew hundred watts at3000 Me/see toafew milli- watts at24,000 Me/see. Magnetrons areself-excited oscillators and their output does nothave the frequency stability possible atfrequencies where power amplifiers areavailable and theoutput frequency isestablished bycrystal-controlled oscillators. When properly designed and used, they exhibit stability adequate tothe demands ofpulse radar. 
 4.1. T urntable Data The turntable data collected by the Institute of Electronics, Chinese Academy of Sciences will be used to show the effectiveness of the proposed method. The real data of a metal tank model are measured in an anechoic chamber on a turntable, which is in uniform circular motion. 
 (There is no reason to  wish to preserve the shape of the received waveform so long as the output signal-to-noise ratio  is maximized.)  Let us return to the receiver output as represented in Fig. 2.1. A threshold level is estab­ lished. 
 The two main uses for data links associated with high performance aircraft are  high bandwidth imagery transmission from a weapon or sensor platform to a second  platform or ground station and low bandwidth transmission of context, targeting data,  guidance, and housekeeping commands.74–79 The largest quantity of data links are  associated with weapons. The waveform selected to transmit this and other data must  not compromise the signature of the platform at either end of the link.8,34–37 There are numerous data links on fighters. Table 5.3 shows air data links that might  be on a fighter platform. 
 The MTI mode is capable of detecting and accurately geo - locating both exoclutter (i.e., target moving faster than apparent terrain motion) and  endoclutter (i.e., target moving more slowly than apparent terrain motion) returns  from moving targets that, in general, have radar cross sections that are smaller than  ch17.indd   23 12/17/07   6:49:35 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 
 POLARIZED PATTERN IE  THE ORTHOGONAL POLARIZATION TO THE MAIN PLANE OF POLARIZATION  OF A RADAR ANTENNA SHOULD BE KEPT AS LOW AS POSSIBLE CONSISTENT WITH RADAR SYSTEM COST 2ATIOS OF COPOLARIZED MAIN 
 The weighting, filtering, and summation of signals are accomplished with the  proper :optical lenses and transparencies. Optical processing is basically two dimensional so  that processing in the range coordinate is possible with the same apparatus. The output of the  optical processor is a maplike photographic film of the terrain, as in Fig. 
 However, thegoal ofmaintaining atleast a partial situation picture byscanning, while simultaneously providing highly accurate positional information onaparticular target being tracked, issoattractive that several equipments have been designed to attain it. The requirement ofhigh scanning speed has ledthedesigners ofallsuch sets touse “electrical” scanners (Chap. 9). 
 Skolnik, M.I. Introduction to Radar Systems ; McGraw-Hill Book Co.: New York, NY, USA, 1962. 3. 
 The choice of these constants for a particular system is determined byits operational use, the accuracy required, the range to be covered, the practicalphysical size, and the problems of generating and receiving the signals. Carrier Frequency The carrier frequency is the frequency at which the radio-frequency energy is generated. The principal factors inﬂuencing the selection of thecarrier frequency are the desired directivity and the generation and receptionof the necessary microwave radio-frequency energy. 
 The ratio of clutter power at the canceler input to the clutter residue at the  output, normalized to the attenuation of a single pulse passing through the unprocessed  channel of the canceler. (The clutter residue is the clutter power remaining at the output of  an MTI system.)  Cancellation ratio. The ratio of canceler voltage amplification for the fixed-target echoes  received with a fixed antenna, to the gain for a single pulse passing thro11gh the un­ processed channel of the canceler. 
 An  example of sea clutter statistics is shown 'in Fig. 13.5, which plots the probability that the  clutter will exceed the abscissa, rather than the probability density function. (The two are  related, however.) It is seen that actual clutter has a greater probability of a large value of sea  clutter than does Rayleigh clutter,: Stated in other terms, the actual distribution has higher  "tails" than the Rayleigh..This means that clutter seen by a high-resolution radar will have a  greater likelihood of false alarm' than Rayleigh clutter if the receiver is designed in the  (13.10)478INTRODUCTION TORADAR SYSTEMS According toLong,9abouthalfthetimethewhitecap formseithersimultaneously with theappearance ofaradarspikeorafractionofasecondthereafter, leadingtotheconclusion thatthewhitecap occursaftertheradarspikedevelops. 
 Quite generally A,will depend onthe area ofthe antenna aperture and not on~, whereas GOwill depend onA/h2. 2.3. Scattering Cross Section ofthe Target.—We have toconsider how thetarget itself enters theradar problem. 
 72. Benedict, T. R., and G. 
 121. D. K. 
 Any use is subject to the Terms of Use as given at the website. Sea Clutter.  SEA CLUTTER  15.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 by Eq. 15.19 clearly bears a resemblance to some of the high resolution returns shown  in Figure 15.11. 
 183–196, 1985.  98. S. 
 Itshouldnotbeconfused withthecircuit-theory concept ofimpedance matching, whichmaximizes thepowertransfer ratherthanthesignal-to-noise ratio. Thefrequency-response function ofthematched filteristheconjugate ofthespectrum of thereceived waveform exceptforthephaseshiftexp(-j2nft1)'Thisphaseshiftvariesuniformly withfrequency. Itseffectistocauseaconstant timedelay.Atimedelayisnecessary inthe specification ofthefilterforreasonsofphysical realizability sincetherecanbenooutputfrom thefilteruntilthesignalisapplied. 
 11.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 Solid-State T ransmitters Michael T. Borkowski Raytheon Company 11.1 INTRODUCTION For commercial applications, the transistor has all but replaced vacuum tube technol - ogy in transmitters operating at VHF and below. 
 112. E. Brookner, “Phased arrays and radars – past, present, and future,” Microwave J ., vol. 
 3. Extended Multiple Aperture Mapdrift Method The spatial variance of the Doppler parameters refers to the fact that these parameters change with the azimuth position of target and can be represented as the functions of fdc. Thus, the errors of the Doppler rate edrand the derivative of the Doppler rate e3rdin (3) become the functions of fdc, i.e., edr(fdc)and e3rd(fdc). 
       .IGHT 6n 
 The use of the SVD is a sufﬁcient information allowing the development of a simple and direct procedure to focus the acquired data without the need for information about the sensor attitudes, path, and SAR system parameters. The aim of this paper is to deﬁne a simple and direct method to obtain good focused images for several application, such as aerial archaeology inspection, agriculture, change detection for land usage and so on. The availability of a blind focusing algorithm can allow the development of simpler SAR systems to be used in low-cost applications in which the highest precision in the focused image is not a strict requirement. 
 FREQUENCY AND ICE MAPPING AND SHIP  LOCATION  )%%% * /CEANIC %NG  VOL /% 
 Naval Research  l.alwracorJ' Report 6796, Washingto11, D.C., Oct. 4, 1968.  115. 
 DOMAIN EXAMPLE  OF THIS PHENOMENON IS SHOWN IN &IGURE  FOR A RADAR WITH  .    HITS PER BEAM 
 19. L. N. 
 Hjelmfelt: Operational Wind Shear Detection and Warning: The CLAWS Experience at Denver and Future Objectives, Preprints, 23d Conf. Radar MeteoroL, pp. 22-26, American Meteorological Society, Boston, 1986. 
 Figure 15.2 is a simplified block diagram of one form of a coherent MTI sys- tem. The RF oscillator feeds the pulsed amplifier, which transmits the pulses. The RF oscillator is also used as a phase reference for determining the phase of reflected signals. 
 2. If errors are unavoidable in a reflecting antenna surface. they should be kept small in extent';  that is, for the same mechanical tolerance, the antenna with the smaller correlation interval  L 2 .----.---,---.,------.-----,  1.0  0.8 - 0.4  02 =l,000  t =100  0.02 0.04 0.06 0.08 0.10  B/o, Figure 8.30 Plot of a.,, versus 0/0i, where aJ is the rms  phase error such that the pointing error will be in thi.:  interval ( -0, 0) with a probability p(O) for arrays with  A/2 spacing; solid curves apply for p(O) :a 0.95; dashed  curves apply for p(O) = 0.99; 01 = angle lo the first null;  D = antenna length. 
 LOBE LOCATIONS FOR BOTH RECTANGULAR AND TRIANGULAR SPACING &OR A RECTANGULAR ARRAY  THE GRAT 
 This results in a change of  polarization and a degradation of the rain can~ellation.~~ 86 It will be recalled from Sec. 12.2  that it is possible for a portion of the transmitted energy to arrive at the target via a surface-  reflected path as well as by the direct path. Similarly, precipitation clutter can result from a  surface-reflected path as well as the direct path. 
 Russell: " Clltra High Frequency Propagation." Jolin Wiley & Sons, Inc.. New  York. 1953. 
 • Resnet models Another model we used is transfer learning the Resnet-50 [ 34] model. Resnet models used a connection method named shortcut connection, as shown in Figure 2. The models are stacked by multiple blocks. 
 Lombardo, P .; Sciotti, M.; Kaplan, L.M. SAR prescreening using both target and shadow information. In Proceedings of the 2001 IEEE Radar Conference, Atlanta, GA, USA, 1–3 May 2001; pp. 
 The   non no static radar requires two transmitters, two receivers, and two antennas to generate tlie  fence. The bistatic radar also needs two antennas, but only one transmitter and one receiver. If  similar equipment is used in the two types of radars, that is, the same antenna, same transmit-  ter, etc.. 
 Rheology is a subject that studies the deformation laws of materials over time under certain conditions (e.g., stress and strain) [ 28]. Rheological parameters (elastic modulus and viscosity) are signiﬁcant factors for characterizing the rheological properties of soft clay. During the operation step of highway 230. 
  "LACKBIRD RECONNAISSANCE PLATFORM !T  ,OCKHEEDS FABLED 3KUNK 7ORKS  HE RECOGNIZED THE IMPORTANCE OF BRINGING THE 2#3 DESIGN ENGINEER INTO THE INNER 
 Since the transmitting antenna must handle high power, it is more  costly to obtain than large receiving apertures. In one type of 0TH radar design, a (rela­ tively) small transmitting antenna with broad azimuth beamwidth is used along with a large  receiving aperture consisting of a number of narrow contiguous beams covering the angle  illuminated by the wide transmitting beam. Thus the complexity of a large transmitting  antenna is traded for a number of parallel receiving channels. 
 Directive gain or directivity is a measure of  the peak power relative to the average power radiated by an isotropic radiator, i.e., a  radiator that radiates energy equally in all directions. Directive gain considers only the  radiated power; thus, antenna losses such as feed mismatch, feed loss, and waveguide  and/or cable losses must also be considered. However, the radar engineer typically  tabulates these losses separately for use in other radar calculations. 
 LOOKING AND DOWN 
 Assume a CIT of 5 seconds and a  tolerable revisit interval of 10 s. Tasks 1 and 4 could be interleaved, for example, by  carrying out five dwells of Task 4, and then one of Task 1, and then repeating this pat - tern. Task 3 is concerned with slow-moving ships, so the revisit interval could be tens 1 Radar 545°N 30°N 15°N 90°W 75°W 60°W0°2 463 45°W30°W15°W0° FIGURE 20.3   Some coverage and tasking options for hypothetical HF radars on a (fictitious) mid- Atlantic island. 
 Thus the presence ofa(mov- ing) target isdetected. Although thesystem just described ishardly practical, apparatus working onexactly this principle but with slight te~hnical modifications can beuseful. InFig. 
 http://envisat.esa.int/object/index.cfm?fobjectid =3772 14. http://www.space.com/spacenews/archive03/spyarch_040903.html 15. http://www.eorc.jaxa.jp/ALOS/about/palsar.htm 16. 
 Cot!f:.otr Ad~lances in ,Marine -Navigatiottal Aids, July 25-27, 1972, IEE (London)  Coliference Publication no. 87. pp. 
 The preceding discussion assumes an equal-path-length feed. However, it is  unlikely that a feed will provide exactly equal path lengths. It will suffice to have the  path lengths kept within one wavelength of each another. 
 40. Jackson, J., and E. Goodall: A 360" Scanning Microwave Reflector, lvlorcotri Rrtl., vol. 
 As0approaches 0degrees, therequired infegrItion timeTbecomes toolargetoprovide beamsharpening sothatimproved resolution isnot obtained inafiniteangular sectoraboutthedirection ofthevehiclevelocity. Inthetelescope, orspotlight, modeveryhighresolution ofaparticular patchonthe groundisobtained bysteering therealantenna aperture todwelllongerthanispossib/t. witha fixedantenna. 
 #/5.4%2-%!352%3   Ó{°Î FROM REMOTE SYSTEMS OR SINGLE PLATFORM SEQUENTIAL BEARING MEASUREMENTS  DIFFERENCE  TIME OF ARRIVAL $4O!  OR HYPERBOLATION  AND 0HASE $IFFERENCE 2ATE 0$2  -ODERN DIGITAL RECEIVER TECHNOLOGY  COUPLED WITH STATE 
 Keller, K. Hayes, and J. Nystuen, “Effects of rain on Ku band  backscatter from the ocean,” J. 
 Jasik. fl.: The Electromagnetic Theory of the Lunclmrg Lens, AFCRC Rept. TR-54-121. 
 Clutter maps store an average background level for each range-azimuth cell. A target is then de- clared in a range-azimuth cell if the new value exceeds the average background level by a specified amount. Optimal Detector. 
 Thayer. and 8. A. 
 This capability permits the observation of smaller-scale temporal and spatial wind-field features than can be obtained from the global 12-hourly rawindsonde (balloon) networks. These smaller-scale mea- surements are important for understanding local and regional weather and for ef- fective forecasting on these scales. It is important to recognize that two-beam systems can measure horizontal winds if the wind field is uniform and if vertical velocities are negligible. 
 The techniques discussed thus Tar attempt to improve the  detection of targets in clutter by increasing the target-to-clutter ratio. There are also several  tecl~niques found in radars for the detection of targets in clutter whose purpose is to prevent  the clutter from saturating the display or the receiver, or to maintain a constant fiilse-alarm  rate (CFAR). They have no subclutter visibility in that tiley offer no ability to see targets  masked by clutter, but they do permit targets large compared to the clutter to be detected that  might otherwise be lost because of the limited dynamic range of the receiving system. 
 POLARIZATION  ERROR IN A TRACKING RADAR SYSTEM IS PURE CROSSTALK SO THAT A SMALL TRUE TRACKING ERROR IN  ONE TRACKING COORDINATE CAUSES THE ANTENNA  TO MOVE IN THE OTHER COORDINATE 4HE ERROR  IN THE SECOND COORDINATE THEN CAUSES THE ANTENNA TO MOVE FARTHER FROM THE SOURCE IN THE FIRST COORDINATE 7HEN THERE IS NO RETARDING EFFECT  THE CROSS 
 Aerosp. Electron. Syst. 
 Chandler, H. M.: Microwave Low Noise Amplifiers For Use in Radar Systems, The Marconi Review,  vol. 35, no. 
 This achieves the benefits of high range-resolution without the need to resort to a  . short pulse. The technique of using a long, modulated pulse to obtain the resolution of a short  pulse, but with the energy of a long pulse, is known as pulse compression. 
 They obtain a precise location of a simulated mov - ing point target, but do not claim to have produced a simulated image of an extended  moving target, such as a vehicle. ‡  Paragraph courtesy of Dr. Marshall Greenspan, Northrop-Grumman Corporation. 
 RONMENTAL EFFECTS MODELS  SUCH AS GASEOUS ABSORPTION AND SURFACE CLUTTER  TO FORM A COMPLETE PROPAGATION PACKAGE 4HE PHYSICAL PROPAGATION PHENOMENA CONSIDERED  BY !0- VERSION  ARE ILLUSTRATED IN 4ABLE  !S CAN BE SEEN FROM THE TABLE  .   4(% 02/0!'!4)/. &!#4/2  &0  ). 4(% 2!$!2 %15!4)/.   ÓÈ°£Ç !0- CONSIDERS ALMOST EVERY ENVIRONMENTAL EFFECT  MAKING IT A HIGHLY DESIRABLE MODEL  FOR USE IN COMPLEX ASSESSMENT SYSTEMS4!",%  0ROPAGATION %FFECTS -ODELED BY !0- %#$ ' #" '&  " &!& " $""' %%' )#" ' #"& %  '%% " ( ' $'    %' #" %% "!&  "  %#$#&''% #(  &(%   &(%*) " $""'   '% & &'   " (% (''% 
 #/5.4%2-%!352%3   Ó{°x , 
 DIMENSIONAL COVARIANCE  VECTOR 2   %6-6   4HE OPTIMUM WEIGHT VECTOR  7}  IS DETERMINED BY MINIMIZING THE  MEAN SQUARE PREDICTION ERROR  WHICH EQUALS THE OUTPUT RESIDUAL POWER   0% : % 6:- 
 Nearly  all such Radar devices of this recent generation possess three horizontal antenna beams of  around 3° each.  The typical range is indicated as 150 m for objects with 1  m2 Radar cross - section.  The direction of th e acquired target is determined with a mono -pulse procedure. 
 J. Fleming: The Navy Space Surveillance System, Proc. IRE, vol. 
 The height H must produce a vertical beamwidth which illuminates only the swath S, that is  to be covered. With such constraints, Eq. (14.15) becomes  SIN = 2Pav p:g0 6cr -- 6,  nf kTo F, RS, sin2 I)  where f = radar frequency. 
 HF OVER-THE-HORIZON RADAR  20.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 or equivalently, in terms of wave frequency,  Fg g ue( ) exp wb w w= −      2 54 ν  (20.10) where  u = wind speed  kc = g/u2  n = 0.74 and be = 0.0081 The exponential term approximates the decay in the spectrum for wave speeds  above the wind maximum velocity. Models that take account of the consequences of  finite fetch and finite duration of the wind stress include the JONSWAP spectrum85  and the model of Elfouhaily et al.86; such effects can lead to substantial changes in the  HF doppler spectrum and hence target detectability, so these models should be used  when applicable. The decrease of wave spectral density with wavenumber is observed to lie close  to a κ–4 power law, as adopted by most models, and by a natural coincidence, this is  balanced by the k04 factor in the first-order scattering coefficient in Eq. 
 322–325,  May 1978. 63. G. 
 GAIN COMMUNI 
 P. H. Hildebrand , “Iterative correction for attenuation of 5 cm radar in rain , ” J. 
 The other channel is similar. except for a 90° phase delay introduced in the reference signal.  The output of the channel B mixer is  EB= k2E0 cos ( ±wdt + </> + ~) (3.7)  H the target is approaching (positive doppler), the outputs from the two channels are  E.~( +) = k2 Ea cos (w4t + </>) EB(+)= k2E0 cos ( wdt + </> + ~) (3.8a)  On the other hand, if the targets are receding (negati\le doppler),  En( - ) = k2 Ea cos ( wd t -</> -; ) (3.8h)  The sign of <1Jd and the direction of the target's motion may be determined according to  whether the _output of channel B leads or lags the output of channel A. 
 R.. and W. L. 
 17.11 . This page has been reformatted by Knovel to provide easier navigation. Contents     xxv   Sidelobe Discretes   ............................................. 
 DIMENSIONAL ADAPTIVE FILTER THAT COMBINES RECEIVE  BEAMFORMING AND DOPPLER FILTERING ! BASIC ILLUSTRATION OF 34!0 IS GIVEN IN &IGURE  OF 7ARD  WHERE A PICTORIAL VIEW OF THE INTERFERENCE ENVIRONMENT SEEN BY AN AIRBORNE  RADAR AND THE CORRESPONDING ADAPTED TWO 
 259-274, March 1985. 66. NASA Announcement of Opportunity: The Earth Observing System (EOS), A.O. 
 INTEGRAL PERIOD MAY BE PREFERRED  SUCH AS THE  
 If, on the other hand,,/b is small  compared witli tlie reciprocal of the pulse duration, the pulses will be modulated with an  aiiiplitude given by Eq. (4.3) (Fig. 4.2~) and many pulses will be needed to extract the doppler  inforniation. 
 Waveform coding includes PRF jitter and PRF stagger, which are helpful for some  deception jammer but don’t help against noise jammer. Waveform coding makes decep - tion jamming or spoofing of the radar difficult, since the enemy should not know or  anticipate the fine structure of the transmitted waveform; as a consequence, it gives  assurance of maximum range performance against such types of jamming. Intrapulse  coding to achieve pulse compression may be particularly effective in improving target  detection capability by radiation of enough average radar power without exceeding  peak power limitations within the radar and by improving range resolution (larger band - width), which, in turn, reduces chaff returns and resolves targets to a higher degree. 
 BEAM AND THE SIDELOBE REGIONS IN THE SAME MANNER AS PARAL 
 Beyond this, there is virtually no quantitative information about the effect of rain on existing sea clutter. TIME (ms) FIG. 13.16 Effect of rain on the correlation function of wind-driven sea clutter; X band, horizontal polarization, wind speed 15 kn, rain rate 4 mm/h. 
 14.1  14.2 Doppler Effe ct  .........................................................  14.2  14.3 Unmodulated CW Radar  ........................................  14.2  Spectral Spreadi ng  ............................................ 
 SION MONOPULSE TRACKING WITH THE CAPABILITY OF SIMULTANEOUS MULTITARGET TRACKING BY SWITCHING ITS BEAM TO EACH OF SEVERAL TARGETS ON A PULSE 
 VII.  Vill.  TX. 
 The unit now being used for frequency in cycles persecondistheHERTZ.Onehertzisonecyclepersecond;onekilohertz(kHz)is one thousand cycles per second; one megahertz (MHz) is one millioncycles per second. WAVELENGTH is the distance along the direction of propagation between successive crests or troughs. When one cycle has been completed,the wave has traveled one wavelength. 
 Senior: Cross Polarization Diagnostics, IEEE Trans., vol AP-20, pp  223-224, March, 1972.  48. Optiz, C. 
  
 13.19] 1’HE RANGB-ll EIGII1’ l.Vl~l CAI’oli 545 theuse ofmechanical repeaters. Aaextreme case isthat ofradar relay (see Chap. 17). 
 To com - plicate the picture still further, it has been found that sea clutter can be dependent on  the direction of the long waves, which includes swell  in the measurement area, so  ideally the directional wave spectrum  should be measured as well. Obviously, it is  unlikely that all of these environmental parameters will be recorded with precision in  every (or even any) sea clutter measurement; so considerable variability in the basic  conditions under which sea clutter data are collected by different experimenters can  be expected. It is of interest to note that in many of the reported measurements of sea  clutter, particularly in the older literature, wide inconsistencies between wind speed  and waveheight may be found. 
 The daytime example has little  horizontal gradient, and the simplifying assumption makes little difference. When  better accuracy is desired, the correct vertical profile can be used for each radiation  angle; also, gradients can be simulated by making the ionosphere nonconcentric  with the Earth. A more complete path analysis should be used in radar performance  assessment and management, but these plasma density contours can be used to  estimate the magnitude of the errors introduced by the assumption of a spherically  symmetric ionosphere. 
 LIMITED DETECTION  AND THERMAL 
 D. Steinberg, “Radar imaging from a distributed array: The radio camera algorithm and experi - ments,” IEEE Trans ., vol. AP-29, pp. 
 25-28, 1977, IEE Confer­ ence Publication No. 105, pp. 313-317, IEEE (New York) Publication No. 
 10.21  Complementary Sequences  ...............................  10.21  Implementation of Biphase-Coded Systems  .......  10.22 Doppler Correct ion  ............................................ 
 This places the operating point at C, which lies on the same curve as C. Because of the dependence of bandwidth on signal level, if possible the logarithmic amplifier should be aligned with signals below the threshold and its pulse response used as a criterion of performance. The pulse response is measured with a pulsed IF signal having much faster rise and fall times than those of the logarithmic device being tested. 
 This follows from the  relationship expressed by Eq. ( 11.54 ). In practice, the radar designer attempts to select the  pulse-repetition period Tp so that all targets or interest occur only in the vicinity of the central  peak, all other peaks being far removed from the region occupied by the targets. 
 195–204, March 1969. 36. T. 
 The batch-to-batch approach allows doppler processing, which is not  compatible with frequency agility on a pulse-to-pulse basis. In a waveform with pulse- to-pulse frequency agility, the center frequency of each transmitted pulse is moved, in  either a random or a programmed schedule, between a large number of center frequen - cies. The frequency of the next pulse cannot generally be predicted from the frequency  of the current pulse.134 Frequency diversity  refers to the use of several complementary  radar transmissions at different frequencies, either from a single radar (e.g., a radar hav - ing stacked beams in elevation by employing different frequencies on each elevation  beam38) or from several radars. 
 Although a narrow beam can, if necessary, search a large sector or even a tiemispherr, it is  not always desirable to do so. Usually, operational requirements place a restriction on the  maximum scan time (time for the beam to return to the same point in spacc) so that the radar  cannot dwell too long at any one radar resolution cell. This is especially true if there is a large  number of resolution cells to be searched. 
 The modi ﬁcations were intended to improve the video response of the indicator and give improved discr imination between small targets and sea returns. It was noted that the use of the discriminator was of great assistance in homing onto a target. It was reported that it was only of slight assistance in search operations, but it was also reported that its use gave no signi ﬁcant decrease in detection range against a schnorkel. 
 Schonland, B. F. J.: "The Flight of Thunderbolts," 2d ed., Oxford, Ciarendon Press, London, 1964  54. 
 Exceptions occuratbroadside, as mentioned, andforsmalleraircraft.38Therearealsoexamples wherenochi-square distribu­ tioncanbemadetofittheexperimental data. Thechi-square distribution hasbeenusedtoapproximate thestatistics ofotha-than­ aircrafttargets. Weinstock38•40showed thatthisdistribution candescribe certainsimple shapes,suchascylinders orcylinders withfinsthatarecharacteristic ofsomesatelliteobjects. 
 Nathanson shows  a plot containing spectral widths at both polarizations from several investigators  over a wide assortment of unspecified sea conditions.65 The points are widely  scattered, but the dependence on wind speed is given roughly, with a rather large  variance, by the expression ∆ ∼ 0.24 U (m/s), which is just the orbital velocity in  Eq. 15.10 with a coefficient about halfway between the values for vertical ( ∼0.15)  and horizontal ( ∼0.30) polarization. For look directions away from upwind, the  peak doppler follows a cosine dependence quite closely, going to zero at crosswind  aspects and turning negative downwind.29 The width  of the spectrum appears to  remain relatively constant.FIGURE 15.14  Qualitative behavior of doppler  spectra of sea clutter looking upwind at low grazing  angles ( after C-band measurements by V . 
 Suppose that itisour ambition todesign aradar system which will locate inazimuth, elevation, and range any aircraft within 20miles with the angular accuracy that can beachieved through the use ofa beam 2°wide inboth azimuth and elevation. The solid angle which the beam itself includes isroughly 0.001 steradlans whereas thehemis- phere tobesearched represents asolid angle of27r. Some 6000” patches” inthe sky must therefore becovered. 
 Thinning in this manner also gives  rise to phase errors which cause a deterioration in the radiation pattern.  Adaptive  antenna^.'^^-^'' An adaptive antenna senses the received signals incident across its  aperture and adjusts the phase and amplitude of the aperture illumination to achieve some  dzsired performance, such as maximizing the received signal-to-noise ratio. The noise may be  either internal receiver noise or external noise, as from jammers. 
 SCALE WAVE 
 For this reason, when the transmitter starts pulsing, a set - tling time of at least 90 pulses must be allowed before useful data is collected.FIGURE  2.48 Time-domain clutter input and output residue as antenna scans past   a point target−100−90−80−70−60−50−40−30−20−100 0 10 20 30 40 50 60 70 80 9 0 100 Pulse Number - iElliptic Filter Response - dBGaussian Beam Residue FIGURE  2.49 Clutter input and residue from elliptic filter. Radar starts radiating at pulse  number 1.−100−90−80−70−60−50−40−30−20−100 0 10 20 30 4 0 50 6 0 7 0 8 0 9 0100 Pulse NumberdBSin X/X Beam Residue ch02.indd   49 12/20/07   1:44:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 A delay line, or pulse-forming network (PFN), is sometimes used as the  storage element since it can produce a rectangular pulse and can be operated by a gas-tube  switch. This combination of delay-line storage element and gas-tube switch is called a line-type  modulator. It has seen wide application in radar because 0f its simplicity, compact size, and its  ability to tolerate abnormal load conditions such as caused by magnetron sparking.1·24·25 A  diagram of a line-type pulse modulator is shown in Fig. 
 OFF BETWEEN ACCURACY AND NUMBER OF CHANNELS A SYSTEM WITH ONE DOF IS LESS EFFICIENT AND REQUIRES MAXIMUM ACCURACY  THAN A SYSTEM WITH  SAY  FOUR DOF !N ADAPTIVE SYSTEM WITH  . DOF CAN  THEORETICALLY SUPPRESS .  n   JAMMERS  REALISTICALLYAS A RULE OF THUMB.  OR  . )F THE NUMBER OF JAMMERS IS HIGHER  THE ADAPTIVE ARRAY IS STILL USEFUL BECAUSE  SOME JAMMER SUPPRESSION IS ACHIEVED WITH AN ACCORDINGLY REDUCED DETECTION RANGE  p  4HE -ARCUM 1 FUNCTION IS DEFINED AS 1AB XXA)A X D XOB   E X P  
 DIRECTED MAIN BEAM %XAMPLES OF 0"2S OPERATING WITH COOPERATIVE BROADCAST TRANSMITTERS IN THE CO 
 FACES HAVE EVER BEEN MEASURED TO THE PRECISION APPROPRIATE FOR CENTIMETER 
  
  
 19.1  19.1 Introducti on  .............................................................  19.1  19.2 Overview of Semiactive CW Systems  ....................  19.3  Doppler Frequency Rela tionships  ...................... 
 cc 
 DENT OF THE DIRECTION OF THE LINEAR POLARIZATION WHEN ROTATED ABOUT A LINE IN THE DIRECTION TOWARD THE RADAR 4ROPOSPHERE  0ROPAGATION  4HE TROPOSPHERE IS TYPICALLY A NONHOMOGENEOUS  MEDIUM FOR PROPAGATION AND WILL CAUSE RANDOM BEAM BENDING &IGURE  ILLUSTRATES  THE APPROXIMATE RELATION OF RMS ANGLE ERROR TO VARIOUS ATMOSPHERIC CONDITIONS  4HE  WORST CASE IS HEAVY CUMULUS CLOUDS  WHICH CAUSE COLUMNS OF AIR  SHADED FROM THE SUN BY THE CLOUDS  THAT ARE COOLER THAN THE SURROUNDING AIR AND CONSEQUENTLY OF A DIFFERENT DIELECTRIC CONSTANT 4HE RESULT IS TYPICALLY A RANDOM BEAM BENDING AS THE RADIATED ENERGY PASSES THROUGH THESE COLUMNS &IGURE  APPLIES ONLY FOR THE PORTION  &)'52%     !NGLE FLUCTUATION VERSUS PATH LENGTH FOR DIFFERENT  TROPOSPHERES  FROM &INAL 2EPORT )NSTRUMENTATION 2ADAR !.&03 
 Therefore, over land  masses ducting is most noticeable at night and usually disappears during the warmest part of  the day.  Another common cause of ducting is the movement of warm dry air, from land, over  cooler bodies of water. Warm dry air blown out over the cooler sea is cooled at the lowest  layers and produces a temperature inversion. 
 TION !S ENGINEERING CONSIDERATIONS SUCH AS THE PROBABILITY OF DETECTION  PROBABILITY OF FALSE ALARM  SIGNAL LOSS FACTORS  AND SIGNAL 
 ING TIME IN TERMS OF PAST SCANS  LONG  THE EFFECT OF AN OCCASIONAL TARGET RETURN CAN BE MINIMIZED !LTHOUGH THE PRIMARY PURPOSE OF THE CLUTTER MAP IS TO PREVENT FALSE ALARMS DUE TO DISCRETE CLUTTER OR CLUTTER RESIDUES THAT ARE AT A FIXED LOCATION  IT MAY ALSO BE NECESSARY TO CONSIDER SLOWLY MOVING POINT CLUTTER IN THE CLUTTER MAP DESIGN  EITHER TO SUPPRESS BIRD RETURNS OR BECAUSE THE RADAR IS ON A MOVING PLATFORM EG  A SHIP  4HE MEMORY OF A CLUTTER MAP IS USUALLY ORGANIZED IN A UNIFORM GRID OF RANGE AND  AZIMUTH CELLS  AS ILLUSTRATED IN &IGURE  %ACH MAP CELL WILL TYPICALLY HAVE  TO  BITS OF MEMORY SO THAT IT WILL HANDLE THE FULL DYNAMIC RANGE OF SIGNALS AT ITS INPUT  WHICH MAKES IT POSSIBLE TO DETECT A STRONG TARGET FLYING OVER A POINT OF CLUTTER SOME 
 Ó°nÈ  2!$!2 (!.$"//+  BY USING RADAR RETURNS IN ADJACENT CELLS IN RANGE AND AZIMUTH 4HROUGH THE USE OF SUCH  SPREADING  AN ADDITIONAL DEGREE OF CONTROL OVER THE CLUTTER MAP VELOCITY RESPONSE CAN BE ACHIEVED !N EXAMPLE OF THE VELOCITY RESPONSE OF A CLUTTER MAP INCLUDING SUCH SPREADING IS  SHOWN IN &IGURE  4HE RANGE EXTENT OF THE CLUTTER MAP CELL IS   MS  THE RADAR RESO 
 From this measurement of clutter doppler within the sampled range  interval, compensation is made over the entire range of observation either by changing the  reference signal from the coho or by adjusting the phase shifter inserted in one of the arms of  the delay-line canceler. Generally, the average doppler frequency or phase shift is obtained by  averaging the sampled range-interval over a number of pulse repetition periods. A single  doppler measurement and subsequent compensation might not suffice over the entire range of  the radar, especially if the radar is elevated as in an aircraft. 
 G. Strauch, “A modulation waveform for short-dwell-time meteorological doppler radars,” J.  Atmos. 
 FIGURE 25.20  Signal-to-noise ratio vs. analog frequency for varying sample jitter020406080100120 1 10 100 2 3 5 7 20 30 50 70tj = 0.5 ps tj = 1 ps tj = 1000 pstj = 250 pstj = 50 pstj = 10 pstj = 2 ps FREQUENCY OF FULL-SCALE SINE WAVE INPUT (MHz)SNR (dB) ENOB14 12 10 8 6 4 ch25.indd   16 12/20/07   1:40:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 TF       WHERE F)&   F  
 ACTIVE HOMING MISSILE BY MODIFYING ITS TRAJECTORY TO MAINTAIN  A    nn DURING ENDGAME &ORWARD 
 Because theanode isatvery high voltage between pulses, any “leakage current” delivers excessive power tothe anode. Asanexample, consider apulse tube normally giving 20-amp pulses with ananode drop of3kvataduty ratio of~m. Such atube will display apeak power anode loss of60”kw, but anaverage power loss ofonly 60watts. 
 This book is, however, an introduction to a  branch of electronics (which is itself a new department  of the general subject of physics) known as radar; and  radar is a development of well-known electrical and  radio principles in a sequence of discoveries in which  the physicists involved in such development have not  been reluctant to admit the entry of genius to their work.  As one of those onlookers permitted for a number of  years to study the sequence of inspired stages of develop-  ment by Sir Robert Watson-Watt and his colleagues, I  should like this book to be a humble tribute to their  work. The reading of it demands no specialized know-  ledge of physics, but an assumption is made that the  reader knows the most elementary mathematics, and is  familiar with the functioning of conventional broadcast-  reception equipment up to the application of super-  heterodyne action. 
 Skolnik (ed.). McGraw-Hill  Book Company, New York. 1970. 
 King: Measurement of the Radar Cross-scctior~ of it Mitt\. l'r~itc,.  IRE. 
 Note that if the nonlinearities in I and Q were identi - cal (a = b; c = d), spurious components at −5w and +3w  would not be present and the  image ( −w) would be proportional to input signal amplitude. Spurious at zero doppler  is not due to dc offset; it is the result of even-order nonlinearities that were omitted  from the above equations. The negative third harmonic is the dominant component  produced by nonlinearity. 
 The designer offuture radar systems, having knowledgeof radar and radar- beacon possibilities, should decide onthe scope ofdesired operational characteristics ofhissystem and then design hisradar setand beacons together inorder toachieve theresult most efficiently. Ifthefrequency ofthebeacon reply istobevery different from the frequency ofthe radar transmitter, itisusually necessary toprovide a separate antenna and receiver forthe beacon signals. The scanning of this second antenna must then besynchronized with that ofthe radar antenna. 
 How fartogowith such provisions and how best toinclude them areproblems that frequently outweigh in importance any other design problem. N-orules can begiven forguid- ance along these lines, butthedegree ofsuccess tobeexpected will depend markedly onthe extent towhich development specialists are familiar with problems ofoperation intheusing organization and onthedegree to which representatives ofthe using organizations have become familiar with thetechnical problems, thepossibilities, and thelimitations ofradar. Requirements forComponent Development. 
 Later this band was subdivided into two bands on either side of the water-vapor absorption frequency. The lower frequency band was designated K11, and the upper band was designated Ka. These frequencies are of interest because of the wide bandwidths and the narrow beam widths that can be achieved with small apertures. 
 995–1009, 1953. 82. D. 
 After each pole-to-pole data collection, the telemetry transferred the accumulated data  to one of the three Deep Space Network (DSN) receiving stations, so that, in conse - quence, the data dump kept pace with the data take, per orbit. Orbit.  For reasons directly attributable to principles of orbital mechanics, it was  much less costly to go into an elliptical orbit at Venus rather than a circular one. 
 TEM COHERENT  AND MIXER PRODUCTS WILL BE IDENTICAL PULSE 
 These two types are exemplified bythe scanners shown inFigs. 9.15 and 9.14 respectively. FIC.95.-Two-dipole feedradiating towarrl theleft. 
 ING TO THEIR TIME 
 SIZE DISTRIBUTIONS IN RAIN OF VARYING FALL RATES UNDER DIFFER 
 Although L band, for example, is shown in the second column of the table as extending from 1000 to 2000 MHz, in practice an L-band radar would be expected to be found some- where between 1215 and 1400 MHz, the frequency band actually assigned by the ITU. Each frequency band has its own particular characteristics that make it better for certain applications than for others. In the following, the characteristics of the various portions of the electromagnetic spectrum at which radars have been or could be operated are described. 
 ϕstands for the azimuth angle of the target position. Point S 0is the position of the antenna phase center (APC). Its coordinates are (rcosθ,rsinθ,h) (2) where rrepresents the length of the boom and θis the rotation angle of the boom. 
 INSULATING SEMICONDUCTOR SUBSTRATE THROUGH VARI 
 T. Randall and  H. A. 
 Ifthe course ofthe aircraft IByE.C.Pollard andL.N.Ridenour.. SEC. 6.11] HEIGHT-FINDING INVOLVING GROUND REFLECTION 185 isapproximately directly toward thestation, therange atwhich the first fade isseen isalso determined bythe target height. 
 Such extended dwell times is one of the funda - mental characteristics of the moving target detector. Moving-Target Detector (MTD) Block Diagram.  Progress in digital signal  processing technology by the mid-1970s made it practical for the first time to improve  the performance of the classical MTI by (1) implementing a parallel bank of FIR filters  to increase the output signal-to-clutter ratio and (2) replacing the IF limiter used in  the past with a high-resolution clutter map for effective false alarm control. 
 17”3. The video switch iscontrolled byaflopover which istriggered tothebeacon position bythebeacon switch pulse and totheradar position bythenext modula- torpulse. The switch pulse issingled out bycoincidence with apulse derived locally (N) attheproper time bydelaying thedecoded modulator pulse. 
 These detections are then used to form and update track  files. The antenna scans in a normal search pattern, and a scan-to-scan correlation is  made on the detections that update the track files. Although tracking accuracies are  less than can be achieved in a dedicated single-target track, multiple targets can be  tracked simultaneously over a large volume of space. 
 POLARIZED R   3NOW 7HEN SNOW COVERS THE GROUND  MUCH OF THE SCATTER IS FROM THE SNOW  RATHER THAN THE UNDERLYING GROUND 3NOW IS BOTH A VOLUME 
 FREQUENCY PROB 
 Clearly, such rapid switching in the receiver requires careful design in order to avoid the effects of switching transients. An approach that avoids transient effects is to use parallel IF strips, each with moderate dy- namic range and fixed gains, and to sample the signal in the channel that is best matched to the signal strength. In all these approaches, it is possible to achieve wide linear dynamic range of the order of 80 dB or greater and to use floating-point digital arithmetic. 
 DELAY CANCELER TRACKS THE SECONDARY SOURCE AND REJECTS IT 3INCE THE PASS AND REJECTION BANDS OF THE TWO CANCEL 
 The azimuth and elevation difference  signals are excited in this guide with E-field polarization oriented at 90o. The  energy in the coupler contains both difference signals coupled as the cosine  and sine of the angular position of the coupler, wst, where ws is the angular rate   of rotation. The hybrid adds the combined difference signals ∆ at the angular   ch09.indd   14 12/15/07   6:07:15 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Trial Report No. 44/35, 13th August 1944 (TNA AIR 65/122)Airborne Maritime Surveillance Radar, Volume 1 3-20. IOP Concise Physics Airborne Maritime Surveillance Radar, Volume 1 British ASV radars in WWII 1939–1945 Simon Watts Chapter 4 ASV Mk. 
 COVERED GROUND /FF 
 MENT OF SCATTERING ELEMENTS APPEARING ON THE SEA SURFACEINCLUDING WEDGES  CUSPS  MICROBREAKERS  HYDRAULIC SHOCKS  PATCHES OF TURBULENCE  AND GRAVITY 
 PULSE -4) AND CASCADED . 
 DEFENDED AREAS BY JAMMING  EJECTING CHAFF  DROPPING EXPENDABLE JAMMERS OR DECOYS  ACTING AS DECOYS THEMSELVES  AND PERFORMING OTHER RELATED %#- TASKS. Ó{°n  2!$!2 (!.$"//+  ! SELF 
 91. M. A. 
 They differ from ordinary mechanical switches in that their impedance isoften appreciable and frequently variable, and inthat many clamps conduct current inonly one direction. Infact, itis often the latter characteristic that enables the device tofunction asa switch. The simple diode isaclamp that isclosed when the anode attempts tobepositive with respect tothe cathode, but open whn thereverse is true. 
 FREQUENCY OPERATION WITHIN A REPETITION PERIOD  CALIBRATED ANTENNAS  KNOWN TRANSMITTER POWER  AND GROUND TRUTH IN THE FORM OF OCEAN WAVEHEIGHT RECORDINGS 7HEN LOOKING INTO AN APPROXIMATELY  KNOT WIND  VALUES OF  R VVn WERE FOUND TO BE CONSTANT WITHIN A FEW DECIBELS FOR OPERAT 
 Lloyd, J. M. Headrick, and J. 
 , 
 An  approximate measure of the spectrum width can be found by taking the differential of the  doppler frequency .f.i = 2(v/l) cos 0, or  4fd = 2; sin O !lO (4.36)  where v = platform speed, l = wavelength, and O is the azimuth angle between the aircraft's  velocity and the direction of the antenna beam. (The negative sign introduced by differentia­ tion of cos O is ignored and the elevation angle is assumed to be zero.) If the beamwidth is . MTI AND PULSE DOPPLER RADAR 141  taken as MJ, then M~ is a measure of the width of doppler frequency spectrum. 
 AND ODD 
 Similarly, theRadar Section oftheNaval Research Laboratory increased itspersonnel to600. The Radio Position Finding section ofthe Signal Corps Laboratories grew into the Evans Signal Laboratory, with apeak personnel ofmore than 3000. Asimilar growth took place atthe Air- craft Radio Laboratory atWright Field. 
 Rept. TG 882, pp. 114–117, March 1967. 
 / 
 POLARIZATION MODE   AND  -(Z DUAL 
 This page has been reformatted by Knovel to provide easier navigation. xxiv     Contents   Electronically Displaced Phase-Center  Antenna  ..........................................................  16.10  Power in the Anten na Sidelobes  ........................ 
 Barrage or broadband jamming is simultaneously radiated across the entire band of the radar spectrum of inter- est. This method is used against frequency-agile systems whose rates are too fast to follow or when the victim's frequency parameters are imprecisely known. Jammer size is characterized by the effective radiated power, ERP = GjPp where G7 is the transmit antenna gain of the jammer and Pj is the jammer power. 
 [ CrossRef ] 23. Sullivan, R.D. A two-cell vortex solution of the navier-stokes equations. 
 LANCE RADAR  IN /KLAHOMA .OTE THAT THE MAJORITY OF RETURNS FROM BIRDS WERE ELIMI 
 TIMES REFERRED TO AS  SUPERCLUTTER VISIBILITY  4HE DIMENSIONS OF EACH CELL ARE A COMPRO 
 In this case, the reduction  in peak quantization lobes is said to be equivalent to adding one bit to the phase shifters in a  100-element array, 2 bits in a 1000-element array, and 3 bits in a 5000-element array.  The maximum pointing error due to quantization, is'15  where 0, is the beamwidth. A four-bit phase shifter, for example would give AOo/O, = 0.049. 
 DOPPLER PLOTS TO THE 7ORLD 7IDE 7EB EVERY HALF 
 The work in [ 14] proposes an interesting method for improving analysis and interpretation of InSAR displacement products. It consists of modelling the displacement time series of man-made structures by using rheological parameters, namely, viscosity and elasticity, which are engineering properties of the soil allowing to deﬁne quantitatively how materials deform in response to forces. The SBAS algorithm was used for processing high-resolution TerraSAR-X data, and then for monitoring a highway segment built on soft clay and a ﬀected by deformation. 
 The reader is referred to Figure 21.13, shown previously, which  illustrates this effect. This spatial pattern does not represent an image of the object of  interest and much effort has been made to develop methods to reconstruct the target  image from GPR data. FIGURE 21.25  Envelope of A-scan sample time series ( Courtesy IEE ) Amplitude τAmplitude  Probability  Distribution ch21.indd   32 12/17/07   2:51:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 There can be  considerable variability in both land and sea clutter. This inherent variability must be under­ stood and properly accounted for in radar system design.  13.3 SEA CLUTI'ER  The echo from the surface of the sea is dependent upon the wave height, wind speed, the length  of time and the distance (fetch) over which the wind has been blowing, direction of the waves  relative to that of the radar beam, whether the sea is building up or is decreasing, the presence  of swell as well as sea waves, and the presence of contaminants that might affect the surface  tension. 
 EFFECTIVE MEANS TO SATISFY THE ACCURACY REQUIREMENTS "ECAUSE TRACKING RADARS TRACK TARGETS NOT ONLY IN ANGLE BUT ALSO IN RANGE AND SOME 
 Sampled signal 4. Bandpass filter 5. Complex passband       signal 6. 
 vol. /\P-21. pp. 
 QUENCY 3&7--&2   WHICH CAN BE TRANSFORMED INTO A RANGE PROFILE  AND INVERSE SYNTHETIC APERTURE RADAR )3!2    -ONOPULSE EXTENT ALLOWS ESTIMATION OF LENGTH  AND WIDTH AS WELL AS SEPARATION OF CLOSELY SPACED AIRCRAFT ! HIGH RANGE RESOLUTION PROFILE ALSO ALLOWS THE SEPARATION OF TARGETS FLYING IN CLOSE FORMATION AS WELL AS THE SEPARATION OF A MISSILE FROM A TARGET ! HIGH RANGE RESOLUTION PROFILE ON A SINGLE  TARGET CAN ALLOW RECOGNITION  ASSUMING THE TARGET ATTITUDE IS KNOWN OR HAS BEEN  GUESSED ,ENGTH  WIDTH  AND LOCATION OF MAJOR SCATTERING FEATURES CAN BE PROJECTED INTO A RANGE PROFILE IF THE ATTITUDE IS KNOWN 4HE NUMBER OF TYPES OF MAJOR CIVILIAN AND MILITARY AIRCRAFT AND SHIPS IS AT MOST A FEW THOUSAND  EASILY STORABLE IN MEMORY 5NFORTUNATELY  RECOGNITION IS LIMITED TO BROAD CATEGORIES RATHER THAN -)' 
 NENT MODULATES A  n PHASE 
 3.Dynamotors. Low-voltage d-c input, high-voltage (orvoltages) d-coutput. IH.E.Keneipp andC.G.Veinott, “A40-kva, 400-cycle Ah-craft Alternator,” .4ZEE Transactions, 63,816-820 (November 1944). 
 The ratio Ro/s,which can becalled the ‘‘subclutter visibility,” gives ameasure ofthe performance ofanMT1 system. When scanning and wind effects arepresent together, along with theeffect ofsystem instabil- ity,wehave togoback toEq. (24) and write itas S=2.4(r&c.m,,,n. 
 Welte, G. R.: Quaternary Codes for Pulsed Radar, pp. 400-408. 
 The design ofthe antenna has agreat influence onthe attainment ofthese requirements. Wehave seen (Sec. 2.1) that under certain conditions themaximum range ofdetection ofagiven target varies asthesquare root ofthearea ofthe antenna. 
 422-432, September, 1968.  2.1. Taylor. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°££ %.6)3!4 4HE  ADVANCED  3!2  !3!2   ABOARD  %3!S  %NVISAT  TAKES  2!$!23!4 
 MULTIPLE TO PROVIDE FINER CHIRP SLOPE RESOLU 
 Theoldermethod isrepresented bythebranch-type du­ plexerandthebalanced duplexer whichutilizegasTR-tubes foraccomplishing thenecessary switching actions. Theothermethod usesaferritecirculator toseparate thetransmitter andreceiver, andareceiver protector consisting ofagasTR-tube anddiodelimiter. ..} Branch-type duplexers. 
 Itrequires neither vacuum tubes nor auxil- iary power supplies. *:E<= o T 2T 3T O n 2Yr 371 4rr Timet (uT o T 2T Timet (a) (b) Fr~. 1044.-Line-type pulser charging waves. 
 Single-frequency, single-polarization radar images are useful. However, use of  multiple polarizations (particularly including cross polarization) and multiple frequen - cies clearly increases their value. Different angles of incidence are most suitable for  different applications. 
 34, no. 33, pp. 30-31,  Aug. 
 The unique requirements outlined inthe foregoing three paragraphs have resulted inareceiver that isconsiderably different from anything previously existing. The design ofi-fand video amplifiers tomeet these requirements will bediscussed inthefollowing sections. 12.4. 
 REPEAT PATTERN DEVELOPS THAT HAS A STIPULATED NUMBER OF DAYS 4HE REPEAT PERIOD &)'52%  4HE 3EASAT SATELLITE  FEATUR 
 Precision SAR processing using chirp scaling. IEEE T rans. Geosci. 
 SEC. 12.4] I-F AMPLIFIER DESIGN 443 noise due totheresistance inthe coils themselves can bekept negligibly small byusing coils ofmoderate Q. The coupling between primary and secondary ispreferably magnetic, since capacitive coupling gives asome- what poorer noise figure. 
 The ensuing Sec. 9.11 shows the application of the aforementioned techniques to the two most common radar families, namely, surveillance and tracking ra- dars. The main design principles (e.g., selection of transmitter power, frequency, and antenna gain) as dictated by the ECM threat are also discussed in some detail. 
 3.3£ suppresses all spurious IF frequencies and spu- rious responses derived from even harmonics of the LO frequency. For the case where the RF phase shift is not obtained by a time delay, the LO frequency and (c) FIG. 3.3 (a) Balanced mixer with an inverted signal, (b) Balanced mixer with an inverted LO. 
 High peak- ing causes a large overshoot and a return toward the target with an additional overshoot. In the extreme, as in system A of Fig. 18.21, the antenna zeros in on the target with a damped oscillation. 
 E.: Variable-elevation-beam Aerial Systems for 1$ Metres, J. IEE, vol. 93, pt. 
  
 TIONS FOR THIS &IRST  THE SCOPE OF %#- TECHNIQUES  IN A BROAD SENSE  IS TO IMPAIR THE TARGET DETEC 
 Inthis case, wewish tomeasure the distance toasingle target, noclutter ispresent, and the target radial velocity may bezero. .Mso, the system must work down tozero range. The system described below was very successful and TransmlthngRecelwngantenna “-J-”* FIG.5.11.—Simplified hiock diagram off-m system for measuring range, itand the proximity fuze arethe two c-w systems that have been most \riclely used. 
 E  <l'.  Range  (bl  Figure 1.3 (a) PPI presentation displaying range vs. angle (intensity modulation); (b) A-scope presenta­ tion displaying amplitude vs. 
 Probability of false alarm = 10-6,  10 hits integrated. The curve labeled  "Rayleigh linear detector" applies  to the conventional receiver with  Rayleigh clutter or noise. The curve  labeled" Chernoff bound" provides  an upper bound to the optimum  detector for the particular clutter  model indicated. 
 € G=4πAR λ2 (3.7)  This then yields:   € PR=PT⋅GT⋅GR⋅λ2 4π()3⋅R4⋅σ=PT⋅AT⋅AR 4πλ2⋅R4⋅σ (3.8)   Under the assumption that a postulated signal -to-noise ratio S/N gives the received power PRmin,  one obtains the maximum range of coverage Rmax.  € Rmax=PT⋅ATAR 4πλ2PRmin⋅σ 4 =PT⋅GTGRλ2 4π()3PRmin⋅σ 4  (3.9)  € PRmin= minimum received power (see section “Noise and Detectio n“)  The dependence of the transmitted power PT and the Radar cross- section σ is proportional by  (  4) the 4th root.  The dependence of the wavelength is essentially more complicated since the  scattering cross section can be heavily frequency dependent. 
 Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 8.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 Nonlinear Frequency Modulation Waveforms.  The nonlinear-FM wave - form has several distinct advantages over LFM.14,16 It requires no frequency domain  weighting for time sidelobe reduction because the FM modulation of the waveform is  designed to provide the desired spectrum shape that yields the required time sidelobe  level. 
 L. Timmoneri, I. K. 
 Early attempts to accoirnt for siich L'CIIOL'S  assumed specular reflect ion from gradients in the refractive index (dielectric constant) of the  atmosphere. Theoretical calculations of the necessary gradients reqtlired to accotrnt for t he  observed angel reflections were excessively large compared to what is found in the real atmo-  sphere. Instead, it is believed that the observed backscattering can be explained as retlections  from atmospheric turbulence associated with inhomogeneities in the refractive index Thcsc  inhomogeneities might be cailsed by differences in the water vapor, teniperaturc, and pressitre  At low altitude, variations in the water-vapor pressure (humidity) are probably the dominant  effect. 
 COINCIDENT COMPETITION BETWEEN THE  DESIRED RETURN FROM DEPTH AND SURFACE CLUTTER AND   RANGE SIDELOBES FROM THE VERY STRONG RETURN FROM THE TOP SURFACE AT NADIR    
 At frequency f2 this same  phase setting steers the beam to a new direction, q0 + ∆q0, which is shown in Frank79  to be  ∆∆q q0 0 =f ftan ( rad) (13.26) As the frequency is increased, the beam scans toward broadside by an angle  that is independent of the aperture size or beamwidth. However, the permissible  amount that the beam may scan with frequency is related to the beamwidth because  pattern and gain deteriorations are a function of the fractional beamwidth scanned.   The angle that the beam actually scans, on the other hand, is related to the per - centage bandwidth. 
 The  continuous aperture appears to represent a lower limit to the impedance variation with  scanning. This is indicated by Allen’s results56 where impedance variation with scan - ning was calculated for dipoles above a ground plane. In spite of increased mutual cou - pling, or perhaps because of it, the more closely the dipoles were spaced, the smaller  the impedance variation with scanning. 
 Barton, D. K., and H. R. 
 Equation (2.1) is not a range equation as it stands, although it can be rewritten in the form\w*wr L (47T)3 Pr \ This equation states that R is the range at which the received-echo power will be Pr if the transmitted power is Pt, target size a, and so forth. It becomes a maximum-range equation by the simple expedient of attaching subscripts to Pr and R so that they become Pr>min and /?max- That is, when the value of Pr in Eq. (2.2) is the minimum detectable value, the corresponding range is the maximum range of the radar. 
 A small subreflector reduces aperture blocking, but it  has to he supported at a greater distance from the main reflector.  The geometry of the Cassegrain antenna is especially attractive for monopulse tracking  radar since the RF plumbing can be placed behind the reflector to avoid blocking of the  aperture. Also, the long runs of transmission line out to the feed at the focus of a conventional  parabolid are avoided. 
 Effects of magneto-ionic propagation on the polarization scattering matrix. Proc. IEEE 1965 ,53, 1089–1091. 
 T. Ransone, Jr., J. A. 
 GAIN MAIN BEAM  MAIN 
 Given  the known (measured or calibrated) receiver gain characteristics, this establishes the con - stant by which a receiver output indication may be converted to an absolute RCS value.  ch14.indd   27 12/17/07   2:47:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 SITE REGION2ECEIVER  /PERATING 2EGIONS2ANGE 2ELATIONSHIP$EDICATED 4RANSMITTER #OOPERATIVE 4RANSMITTER .ONCOOPERATIVE 4RANSMITTER #O 
 Geophys. Res ., vol. 99, pp. 
 J. Lewis (eds.), Principles and Applications of Imaging Radar ,   New York: Wiley, 1998. 31. 
 AES-8, pp. 757-761,  November, 1972.  40. 
 The lower portion of Figure 4.16 will be used in the  stability discussion to follow. Stability.  To achieve the theoretical clutter rejection and target detection and  tracking performance of a pulse doppler system, the reference frequencies, timing sig - nals, and signal processing circuitry must be extremely stable.48–52 In most cases, the  major concern is with short-term rather than long-term stability. 
 M. A. Cervera and W. 
 TRACK DIRECTION  THE ANTENNA SIZE HAD FAR 
    
 The linear detector, like any detector law, approaches the square-law  characteristic for small signal-to-noise ratios.  Logarithmic detector. If the output of the receiver is proportional to the logarithm of the input  envelope, it is called a logarithmic receiver. 
 Iftheaprioriprobability p(SN)canbeconsidered constant, thecomputation of theaposteriori probability isequivalent tomultiplying thereceived signaly(t)bythesignal waveform Sj(t)andintegrating withrespecttotime.Thisisthesameprocessperformed bythe cross-correlation receiver (Sec.10.3)andisequivalent totheoperation ofamatched filter (Sec.10.2). ;\limitation ofthemethod ofinverseprobability basedontheapplication ofBayes'ruleis thedifficulty ofspecifying theaprioriprobabilities. Inmostcasesofpractical interest, oneis ignorant oftheaprioriprobabilities. 
 A change of l °C might result in a 1 ° phase change. Hence.  they usually must be operated in a temperature-controlled environment. 
 Parameters V alues Radar look direction 180◦ Incidence angle 25◦ Radar frequency C-band Polarization HH Platform height 800 km Platform velocity 7455 m/s Wind direction 225◦ Wind speed 4 m/s, 7 m/s, 10 m/s Rotation direction of current ﬁeld counterclockwise Maximum Current velocity 1 m/s In Figure 16, the red arrow represents the wind direction, the black arrow represents the radar look direction, and the blue arrow indicates that the eddy current ﬁeld rotates in the counterclockwise direction. As shown in Figure 16a–c, wind speed does not change the brightness variations along the eddy spirals, but affects the brightness variations of the overall SAR image. With increases in wind speed, the entire simulated image becomes brighter. 
 An A-scope modified by the inclusion or an adjustable notch for measuring distance.  PP/, or Plan Position Indicator (also called P-scope). An intensity-modulated circular display on which  echo signals produced from reflecting objects are shown in plan position with range and azimuth  angle displayed in polar (rho-theta) coordinates, forming a map-like display. 
 To improve detection, frequency diversity  is often used on prime systems. IALA has issued detailed recommendations37 on the operational and technical per - formance requirements for VTS equipment. There is much useful information in the  recommendations, and they are essential for procurers and designers of VTS radar  equipment. 
 ZERO VALUE TERMED THE STEADY 
 RANGE LOCATION SINCE ANGLE DATA  WITH ITS RANGE 
 In addition to the range penalty, the receiver will also suffer  increased clutter levels and angle measurement errors. Despite these limitations, the  Binet  floodlight receiver was found quite adequate for measuring three dimensional  vector wind fields.2,42 Multiple Beams.  A bistatic receiver can use multiple simultaneous fixed receive  beams to cover the surveillance sector, which again restores the surveillance frame  time. 
 These differ by an amount proportional t  the altitude of the aircraft. The receiver measures this  frequency difference and shows the result on a dial as  terrain clearance. Terrain clearance may also involve  the measurement of clearance obliquely ahead, as in the  approach to or flying through steeply mountainous  country. 
 24 Confocal dual reflector antenna fmain  fsubfsubParabolic  Main Reflector  Common  FocusDmain Parabolic  SubreflectorDsubfmain  αAESAαRef = αAESA/ Mag Phased  Array Feed Mag =   ch12.indd   24 12/19/07   2:38:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 
 TARGET RANGE M   0AV   4RANSMITTED AVERAGE POWER 7   TO   3IGNAL OBSERVATION OR INTEGRATION  TIME  '4   4RANSMITTING ANTENNA POWER GAIN  '2   2ECEIVING ANTENNA POWER GAIN  K   7AVELENGTH M   R"   "ISTATIC RADAR CROSS SECTION M   &4   0ATTERN PROPAGATION FACTOR FOR TRANSMITTER 
 16”7), arectifier isincluded inthe circuit ahead ofthe PPI. Inorder togetgood cancellation, the signals inthe two channels of the amplifier must match very closely intime. This means that the r-—-— -——— ——-—— --- Two.channel amplifier1 III ICarrierI Delayline+amplifler OscillatorIm andIamplifier -1C?rrier Iamplifier I,/ _Videosignalsfrom MTIreceiverL’___-_____ .–––– –-l MTIvideoouttoPPI+ FIG. 
 Precision velocity update (PVU) is used for naviga - tion correction to an inertial platform. Although GPS updates are commonly used to  provide navigation in many situations, a military aircraft cannot depend solely on its  availability. Furthermore, inertial sensors are used to fill in between GPS measure - ments even under the best circumstances. 
 Only under quite special circumstances will there actually be  an identifiable surface-wave at that “frequency” that would justify the term Bragg  resonance  in its original sense, which, after all, was a resonance in an ordered crystal  lattice of discrete scatterers. Although authors often refer to “free Bragg waves,” such  objects are found primarily among the parasitic capillaries  referred to in Section 15.2  or among the ring waves  propagating out from the impact of a falling drop. This raises  a question about the meaning of such often-used terms as Bragg wavelets, Bragg  patches , and so on, as if such things had a real existence outside of their emergence  as an artifact of a filter operation. 
 Opinions about the utility of the various vacuum tube transmitters mentioned  here will be briefly given next, with the suggestion to the reader to keep in mind that  circumstances can change and these opinions can change as well. These opinions are  not “written in stone,” and are not likely to be universally agreed to by all those who  work in radar. But that is the nature of any engineering endeavor. 
 This is more an indication of the problems involved in technical book publishing rather than problems with the health of radar or the . availability of material to include. It was not an easy task to constrain the chapter authors to a limited page budget, and I am appreciative of their efforts to keep the size of their chapters within the allocated number of pages. 
 TEMS ! SIMPLE EXAMPLE IS A COMBINED 8 
 SPECIFIC ISSUES ARISE  NEITHER  OF WHICH CAN BE SOLVED BY THE USUAL EXPEDIENT OF INCREASING THE RADARS TRANSMITTED  POWER 4HE FIRST PROBLEM IS CLUTTER &ROM ORBITAL ALTITUDE  SCATTERERS ON THE SURFACE FAR FROM NADIR MAY GENERATE STRONG BACKSCATTER THAT APPEARS AT THE SAME RADAR RANGE AS THE SIGNALS REFLECTED FROM DEPTH  AS SUGGESTED IN &IGURE  4HE PROBLEM IS COM 
 Admittedly, this is somewhat arbitrary, but the choice of 1° is based upon several decades of expe- rience. Al0 beam will provide resolution of 2 km at a range of 120 km. Because thunderstorms contain important spatial features, such as heavy precipitation shafts and updraft cores, with horizontal dimensions of the order 1 to 5 km, a 1° beam is reasonably well matched to the phenomena being observed. 
 The detection performance of  the moving-window detector is about 0.5 dB worse than the optimal detector which weights  the returned signals by the fourth power of the antenna voltage pattern.63 The angular loca­ tion of the target can be estimated from the output of this detector by laking the midpoint  between the first and last crossings of the detection threshold, or by taking the maximum value  of the running sum. After correcting for the bias, the accuracy of the location measurement is  only about 20 percent worse than theoretical.63  Recirculating-delay-line integrator.65 -70 The delay-line integrator, or moving-window detec­ tor, described above requires that a number of pulses, equal to that expected from the target,  be held in storage. A simplification can be had by recirculating the output through a single  delay line (Fig. 
 Examples of such data are given in Figs. 2.18 to 2.20. The radar cross  section of the T-38 aircraft at head-on incidence is shown in Table 2.1. 
 The angular error of the beam-splitting procedure  is about 20 percent greater than the optimal estimate. For large signal-to-noise ratios,  the accuracy (rms error) of the beam-splitting and maximum-return procedures will be  limited by the pulse spacing8 and will approach  σ θ θ (ˆ)= ∆ / 12 (7.6) FIGURE 7.3  Block diagrams of various detectors. The letter C indicates   a comparison, t is a delay, and loops indicate feedback. 
 ERS THEY TYPICALLY PROVIDE BROADER BANDWIDTHS  GREATER GAIN CONTROL ACCURACY  GREATER PHASE STABILITY  IMPROVED DYNAMIC RANGE  AND FASTER SWITCHING SPEED 4HE CHOICE BETWEEN VOLTAGE CONTROLLED AND SWITCHED ATTENUATION DEPENDS ON TRADE 
 BEAM EFFICIENCY AND DIFFERENCE 
 FORMS PARAMETERS DEPEND UPON THE TYPE OF SEARCH WAVEFORM THAT PRODUCED THE TARGET DETECTION 4HE 4RACK !CQUISITION WAVEFORMS THRESHOLDS ARE SET TO REJECT FALSE ALARMS AND REDUCE THE FALSE TRACK INITIATION RATE TO LESS THAN ONE PER HOUR &OR 4RACK !CQUISITION  A SEARCH DETECTION FROM 63 WOULD REQUIRE A (273 WAVE 
 Three main approaches, adaptive thresholding, nonparametric detec- tors, and clutter maps, have been used to solve the false-alarm problem. Both adaptive thresholding and nonparametric detectors are based on the assumption that homogeneity exists in a small region about the range cell that is being tested. The adaptive thresholding method assumes that the noise density is known ex- cept for a few unknown parameters (e.g., the mean and the variance). 
 Yamauchi: A Japanese 3-D Radar for Air Traffic Control, Electronics, p. 68, June 21, 1971. 13. 
 ITY OF  TARGETS ON SHIPS LESS THAN  GT  TARGETS ON SHIPS BETWEEN  AND   GT AND  TARGETS ON SHIPS OVER   GT )N ADDITION  SHIPS OVER   GT MUST HAVE AN AUTOMATIC TARGET ACQUISITION CAPABILITY !CTUAL SYSTEMS COMMONLY EXCEED THESE MINIMUM REQUIREMENTS 4ARGETS WITH A MAXIMUM RELATIVE SPEED OF  KT MUST BE TRACKABLE THIS REQUIREMENT IS INCREASED TO  KT FOR RADARS ON VESSELS CAPABLE OF MORE THAN  KT /N THE BRIDGE  THE NAVIGATORS REQUIREMENTS TO AID COLLI 
 I RE, vol. 43, pp. 698-700, June, 19SS. 
 W. Davis, and J. K. 
 18. Jacomini, 0. J.: Weighting Factor and Transmission Time Optimization in Video MTI Radar, IEEE  Trans., vol. 
 C. Daley: An Experimental Study of a Sea Clutter Model, Proc. I EEE, vol. 
 Ifthis type isused, thesine orcosine voltage isused tobias thecathode ofthediode, and thebias oftheanode isadjusted togive thedesired delay Aatzero scanner angle. The value ofBisdetermined jointly bytheslope ofthesawtooth and theamplitude ofthesine and cosine voltages from thescanner. The basic pulse, sine pulse, and cosine pulse arepassed totheusual three-pulse coder along with themodulator trigger signal, which isderived from afixed-delay circuit triggered bythecosine pulse. 
 The broadside linear-array antenna  may be used where broad coverage in one plane and narrow beamwidth in the orthogonal  plane are desired. The linear array can also act as a feed for a parabolic-cylinder antenna. The  combination or the linear-array feed and the parabolic cylinder generates a more controlled  fan beam than is possible with either a simple linear array or with a section of a parabola. 
 INDICATOR 00)  PHOTOGRAPHS  TAKEN YEARS AGO  ARE  INCLUDED IN THIS CHAPTER TO PROVIDE A BETTER UNDERSTANDING OF THE ENVIRONMENT THAT IS DIFFICULT TO APPRECIATE WITH MANY MODERN RADARS 4HESE PHOTOGRAPHS SHOW -4) OPERA 
 IIIB were described in in a TRE Memorandum in August 1943 [ 12]. Previously ASV Mk. III and H 2S Mk. 
 With these interpretations, the radar equation (Eq. 20.2) can be used to model  the performance of skywave radars when noise, not clutter, is setting the limit to  target detectability, noting that the complexity and statistical nature of ionospheric  propagation and the external noise environment means that it is often necessary  to apply the equation to probability distributions, not scalar values of the param - eters. When the target’s velocity places its doppler shift beyond those of any clut - ter returns, the noise-limited model is appropriate, but there are two important  situations where this is not the case. 
 Two schemes toimprove heat transfer are shown inFig. 11.26. In a,the internal and external blowers aredirected atthe same portion of thewall, which has some fins atthat point atleast toincrease effective area. 
 In addition to the United States, these designa - tions can also be used by Canada, Australia, New Zealand, and the United Kingdom.  Special blocks of numbers are reserved for these countries. Further information can  be found on the Internet under MIL-STD-196D. 
 [; F-  F" SINA  =  
 D. Griffiths and C. J. 
 FIGURE 6.19  Hilbert transformer architectureD Q(m)A/D y(m) = I(m) + jQ(m) DI(m) x(t) x(n) h2(n)h1(n) ~x(n) FIGURE 6.20  Spectra of Hilbert transformer receiver B F0 −F0F w0w~X(w)X(F) −w0 p −p w0 = 2pk|DwX(w) p wY(w) p−p −p(a) (b) (c) (d)k = 1, 2, … ch06.indd   43 12/17/07   2:04:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 IRE, vol. 48, pp. 1630-1635, September, 1960. 
 It is  highly recommended  that before a detector is chosen the radar video from the envi - ronment of interest be collected and analyzed and that various detection processes be  simulated on a computer and tested against the recorded data. FIGURE 7.22  Resolution capability of a log detector that used half of the references cells with   lower mean ( after G. V . 
 This is known as a Barker code of length 13. (b) Autocorrelation function of (a), which is an  approximation to the output of the matched filter. (c) Block diagram of the filter for generating the  transmitted waveform of (a) with the input on the left. 
 P.: Reduced Sidelobes for Butler-Matrix-Fed Linear Arrays, IEEE Trans., vol. AP-17,  pp. 645-47, September, 1969. 
 BASED ALTIMETER IS ALSO TO MEASURE THE DISTANCE BETWEEN  THE RADAR AND THE SURFACE  THE MOST COMMON APPLICATION IS DETERMINATION OF THE LOCAL SEA LEVEL RELATIVE TO THE %ARTHS GEOID  e RATHER THAN THE HEIGHT OF THE SPACECRAFT 4HE  REFERENCE FOR THIS MEASUREMENTTHE ORBITAL HEIGHT OF THE SPACECRAFTMUST BE KNOWN BY OTHER MEANS TO WITHIN A FEW CENTIMETERS 3EA 
 The second loop is the receiver  gain control (AGC). Altimeter height measurement is given by the setting of the FIGURE 18.10  The pulse-limited condition: Over a nominally level flat  surface, the altimeter’s short pulse ( a) reflects first from an area that may be  much smaller than the footprint illuminated by the antenna pattern ( b). (a) (b)Compressed pulse length rRound-tr ip pulse propagation bh 2rpSea surf ace Annuli of equal areas ApPulse-limited f ootpr int 0 1 2 3 Relativ e time dela y t/r ch18.indd   39 12/19/07   5:15:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 (ILL    #HAPTER    * 2YAN AND # +IRBY  h)CEBERG DETECTION PERFORMANCE ANALYSIS v 2EPORT 40 %  4RANSPORTATION  $EVELOPMENT #ENTRE  4RANSPORT #ANADA     * . "RIGGS  h4ARGET DETECTION BY MARINE RADAR v )NSTITUTION OF %LECTRICAL %NGINEERS NOW THE  )NSTITUTION OF %NGINEERING AND 4ECHNOLOGY   ,ONDON     h4HE INTERNATIONAL CONVENTION FOR THE SAFETY OF LIFE AT SEA 3/,!3    v )NTERNATIONAL -ARITIME  /RGANIZATION  ,ONDON  AS AMENDED  )NTERNATIONAL %LECTROTECHNICAL #OMMISSION  WWWIECCH  h-ARITIME NAVIGATION AND RADIOCOMMUNICATION EQUIPMENT AND SYSTEMS3HIPBORNE RADAR v )%#    )NTERNATIONAL %LECTROTECHNICAL #OMMISSION  'ENEVA    h-ARITIME NAVIGATION AND RADIOCOMMUNICATION EQUIPMENT AND SYSTEMS'ENERAL REQUIREMENTS v  )%#   )NTERNATIONAL %LECTROTECHNICAL #OMMISSION  'ENEVA    h-ARITIME NAVIGATION AND RADIOCOMMUNICATION EQUIPMENT AND SYSTEMS$IGITAL INTERFACES v )%#   SERIES   )NTERNATIONAL %LECTROTECHNICAL #OMMISSION  'ENEVA  h2EGULATIONS REGARDING THE MINIMUM REQUIREMENTS AND TEST CONDITIONS FOR RADAR EQUIPMENT USED  FOR 2IVER 2HINE AND INLAND WATERWAYS v #ENTRAL #OMMISSION FOR THE .AVIGATION ON THE 2IVER  2HINE  3TRASBOURG    h-ARITIME NAVIGATION AND RADIOCOMMUNICATION EQUIPMENT AND S YSTEMS2ADAR FOR CRAFT  NOT IN COMPLIANCE WITH )-/ 3/,!3 #HAPTER 6 v )%#   )NTERNATIONAL %LECTROTECHNICAL #OMMISSION  'ENEVA    2 'ANGESKAR AND  'RNLIE  h7AVE HEIGHT MEASUREMENTS WITH A STANDARD NAVIGATION SHIP RADAR   RESULTS FROM FIELD TRIALS v PRESENTED AT 3IXTH )NTERNATIONAL #ONFERENCE ON 2EMOTE 3ENSING FOR -ARINE AND #OASTAL %NVIRONMENTS  #HARLESTON  3OUTH #AROLINA  . 
 QUENT TO THE &)2 FILTERING USED TO GENERATE  )1 DATA OR COMBINED WITH THESE FILTERS  )T SHOULD BE NOTED THAT TO CORRECT FOR FREQUENCY AND PHASE VARIATION ACROSS THE RECEIVER BANDWIDTH REQUIRES &)2 FILTERS WITH COMPLEX COEFFICIENTS  APPLIED EQUALLY TO ) AND 1 DATA 2EAL VALUE COEFFICIENTS TYPICALLY USED IN )1 GENERATION PROVIDE FIL 
 MATION  TRACKING  ETC 7ITH ONLY ONE BEAM AT A TIME  THERE MAY NOT BE ENOUGH TIME AVAILABLE TO PERFORM ALL OF THE REQUIRED FUNCTIONS ! DIGITAL BEAMFORMER ALLOWS THE FORMATION OF MULTIPLE SIMULTANEOUS BEAMS  ALLOWING THE VOLUME SURVEILLANCE FUNC 
 AES-26, no. 1, pp. 57–67, 1990. 
 TER 4HE SYNTHESIS PROCEDURE CALCULATES APPROPRIATE FLUCTUATING TARGET AND CLUTTER RETURNS FROM ANY DESIRED THEORETICAL MODELWHICH COULD ALSO  IN PRINCIPLE  INCLUDE MODELS DERIVED FROM RECORDED DATA OF REAL TARGET AND CLUTTER REFLECTIONS "ECAUSE THE SIMULATED SIGNAL IS PREDOMINATELY ENTERING THE RADAR THROUGH THE SIDELOBES OF THE RADAR ANTENNAEXCEPT WHEN THE RADAR MAIN BEAM ALIGNS WITH THE SIMULATOR ANTENNATHE SYNTHESIZED SIGNAL NEEDS TO BE AUTOMATICALLY ADJUSTED IN AMPLITUDE TO COMPENSATE FOR THE ACTUAL SIDELOBE SENSITIVITY IN THE DIRECTION OF THE SIMULATOR %FFECTIVELY  THE SYNTHESIZER HAS TO AMPLIFY THE TRANSMITTED SIGNAL ACCORDING TO THE INVERSE OF THE AMPLITUDE OF EACH PULSE RECEIVED FROM THE RADAR 4HE CHALLENGES IN DESIGNING AN AFFORDABLE SYSTEM INCLUDE THE LARGE DYNAMIC RANGES THAT HAVE TO BE ENCOMPASSED AND THE PROCESSING SPEED NEEDED TO DETERMINE THE CHARACTERISTICS OF THE TRANSMITTED SIGNAL )N PRINCIPLE  A NUMBER OF CLUTTER AND TARGET MODELS COULD BE ESTABLISHED BY INTER 
 With the same notation as for Table 17.5, the factor Q is [K/R/ (CIN)Bn]112^ and the rms allowable fractional AM is equal to Q, as is the rms phase modulation (given in radians). The rms PPM or single-edge PWM allowable modulation (given in seconds) is TQ. 77.7 RANGEPERFORMANCE Chapter 2 discusses the general radar range equation and the calculation of de- tection probability. 
 The beam.. is rapidly scanned through t~llire elevation  coverage in the time the antenna rotates .on.e.._azim.y~. The(3!) vnformation is  obtained by the S:?9uential_ scan!)ing__o.[_a single b~Jl.Ill..aS fQ!!lJ2.?_~cd withttfu simultaneous  multiple beams described jn the above. 
 Ifaradar fitted with such a device isbeing used forthenavi- gation ofamoving ship oraircraft, thecharts used forprojection must k,,” , beadjustable and easily changed. h/“ PPI Methods have been worked outfor ‘transparent ‘irror ..’~-----Tube storing alarge amount ofmap .;:&:$ information inasmall space by,.5&\?-,;’,/ la+,! theuse ofmicrofilm, and forpro- w’lQPLens tiding motion ofthe chart in---1. theprojector. 
 MOVING TARGETS  REGARDLESS OF THEIR UNKNOWN VELOCITY 4HE PROCESSING PROCEDURE THEN AUTOMATI 
 24,  pp. 720-727, June, 1953.  54. 
 Generally to address time-delay adaptive weighting, more complexity  is required with a third dimension for adaptive weights—“fast-time” or returns from  adjacent sampled range cells. This extension can be extremely computationally inten - sive and further burden the sample support problem alluded to previously . When evaluating a radar design and trading off various waveforms and STAP pro - cessing techniques, it is important to include in the analysis key drivers such as signal  bandwidth, clutter internal motion, platform motion, antenna scanning motion, the  amount of sample support available from nonhomogenous and nonstationary clutter  environments, and other effects such as large target samples effecting the adaptive  weight solution. 
 L. Johansen, R. F. 
 FILTER OUTPUT POWER FOR THE REFERENCE TARGET IS PROPORTIONAL TO THE AMBIGUITY FUNCTION AND IS GIVEN BY   0 REF   9U          4HE MATCHED FILTER OUTPUT POWER FOR THE SECOND TARGET  EVALUATED AT THE PEAK OF THE  REFERENCE TARGET  IS    0   9U S  FD     4HE SECOND TARGET IS UNRESOLVED FROM THE REFERENCE TARGET AT LOCATIONS IN THE DELAY 
 Normal target motion will result in different doppler shifts for each major scat - terer of a rigid-body target, and the shifts will be a function of the displacement of the  scatterer from a reference point such as the center of rotation of the target’s random  motions. Therefore, a high-resolution doppler system can resolve major reflectors and  locate them in cross range as a function of the doppler difference from the reference  reflector. This technique, called inverse synthetic aperture radar (ISAR),  uses the target  motion for the needed aspect change, instead of radar motion as used in conventional  synthetic aperture radar, to obtain detailed cross-range target image information.44,45 9.9 OTHER EXTERNAL CAUSES OF ERROR Multipath. 
 On Sept. 28, 1983, the U.S.S.R. launched the Cosmos 1500 satellite with an SLR for the all-weather probing of the surface and ice cover of the earth's seas and oceans.38 (The SLR was mentioned in Sec. 
 1·, in knots. and ). in meters,  .rd  A plot of this equation is shown in Fig. 
 This avoids the need for large spacings, oil filling, or encapsulation, thus saving size and weight and lead- ing to higher reliability of the power supplies as well as of the microwave power amplifiers themselves. 3. Transmitters designed with solid-state devices exhibit improved mean time between failures (MTBF) in comparison with tube-type transmitters. 
 Such radars can make doppler measurements throughout the range of  altitudes from a few hundred meters to 20 km or more above the surface, depending  upon the wavelength selected and the power-aperture product available. These radars  have the ability to measure high resolution winds continuously, which permits the  observation of smaller scale temporal and spatial wind-field features that cannot be  obtained from the global 12-hour rawinsonde (balloon launch) network. These smaller  scale measurements are important for understanding local and regional weather and  for effective forecasting on these scales. 
 PASS )N3!2  4HE %23 3!2 INSTRUMENT WAS  A SUBSET OF A COMBINED RADAR GROUP  THE !CTIVE -ICROWAVE )NSTRU MENT !-)   COM 
 Pulse radar . This is a radar that radiates a repetitive series of almost-rectangular  pulses. It might be called the canonical form of a radar, the one usually thought of  as a radar when nothing else is said to define a radar. 
 3.1, pulse compression is provided by the cascade combination of IF filter and digital decoders (correlators) after doppler filtering. Similarly, Chaps. 18 and 20 describe tracking radars and height finding radars, but the peculiarities of the receivers required to perform these functions will be mentioned briefly. 
 Calibration The range to a target can be measured most accurately on the PPI when the leading edge of its pip just touches a ﬁxed range ring. The accuracy ofthis measurement is dependent upon the maximum range of the scale in use.Representative maximum error in the calibration of the ﬁxed range rings is75 yards or 1 1/2percent of the maximum range of the range scale in use, whichever is greater. With the indicator set on the 6-mile range scale, theerror in the range of a pip just touching a range ring may be about 180 yardsor about 0.1 nautical mile because of calibration error alone when the rangecalibration is within acceptable limits. 
 DRAIN BREAKDOWN VOLTAGE   60 IS THE PINCHOFF VOLTAGE  AND  6+ IS THE KNEE VOLTAGE 4HESE  TRANSISTOR PARAMETERS DEFINE THE TRANSFER CHARACTERISTICS IN THE ) 
 ONLY NULLING TO MAINTAIN THE APERTURE EFFICIENCY /N RECEIVE  AMPLITUDE WEIGHTING ACROSS THE ARRAY IS TYPICALLY USED TO PRO 
 The most widely used wartime types are pictured in Fig. 13.5. The following intercomparison ofexisting designs ofelectro- static and magnetic tubes can bemade. 
 649 -658, May  1989   − E. Heidrich; W. Wiesbeck, "Features of advanced polarimetric RCS -antenna mea s- urements," in Proc of the IEEE AP -S Int. 
 ( 11.17), or  b(!) = y(lE/~o) 112 (11.40)  where y is the effective aperture width defined by  <X) f (2nx)2IA(x)l2dx  2 ·-<X)  }' = <X) f IA(x)l2dx  -<X) (11.41)  The theoretical angular error of an antenna with a rectangular amplitude distribution  across the aperture is  bO = 1tD(2E/N0)112 (11.42a)  The effective aperture width is 21t times the square root of the normalized second moment of  jA(x)l2 about the mean value of x, taken to be at x = 0. The half-power beamwidth 08 of a  rectangular distribution is 0.88,l/D, where 08 is in radians. Therefore  Q~8~ ( ) oO = (2E/No) 112 11.42b . 
 I, pp. 620–628, 1981. 61. 
 32. T. Chu and P. 
 R. J. Doviak and D. 
 A simple form, with which to begin, is given below: Pr = ^ (23.1) where (3 is a constant dependent upon radar system parameters, r is the range, and a is the radar cross section. It is in the calculation of a for meteorological targets that the radar range equa- tion differs from that for point targets, cr may be written <j = T]V (23.2) where r\ is the radar reflectivity in units of cross-sectional area per unit volume and V is the volume sampled by the radar. T) can be written as N TI = ]>>, (23.3) /=i . 
 Rep/.248,Oct.30. It>52. 11.1.Elliot.R.S.:Mechanical andElectrical Tolerances forTwo-dimensional Scanning Antenna Arrays, IRE]rCl/ls.,vol.AP-6.'pp. 
 They cover both coastal and waterway installations. Many major rivers  of the world carry vast amounts of cargo on ships that can be surprisingly large. The  meandering nature of rivers and relatively abrupt turns in canal systems, together with  the natural and manmade obstructions to radar, mean that waterway vessel traffic sys - tems are generally covered by many low-power radar heads on relatively low towers. 
 OneofthefirstCFARreceivers tobedescribed intheliterature usedtheoutputofapost­ detection integrator (low-pass filter)toestimate theaveragenoise.Thiswasthenappliedasa feed-forward signaltocontrol thethreshold leveltomaintain thefalse-alarm rate constant.71.72Thenoisehadtoremainconstant foratimecorresponding tothetotalnumber ofpulsesreturned fromthetarget.Another CFARtechnique isthehardlimiter,sometimes calledtheDickefix.72-74Thisconsistsofabroadband IFfilterfollowed byahardlimiterand anarrow-band matched filter.Thehardlimiterissetlowenoughtoensurethjtreceivernoise islimited.Thustheoutputisunaffected bythelevelofthenoise.Asignal,however, causesthe outputofthematched filtertoincrease byafactorM,equaltotheratioofthebandwidth of thebroadband filtertothebandwidth ofthenarrow-band (matched) filter.ThisformofCFAR maynotbedesirable withMTIsincehardlimiting reduces theimprovement factororthe clutterattenuation (Sec.4.8).Hardlimitingalsointroduces anadditional loss,Thelargerthe ratioofthebandwidths M,thelesstheloss.Forexample, fora0.5probability ofdetection and a10-3probability offalsealarm,thelossis1.0dBforM=100,2.2dBforM=20,and7dB forM=10.73InessencetheDickefix(thatuseswideband limiting) samples theadjacent resolution cellsinthefrequency' domain, ascompared tothecell-averaging CFARthat samples thebackground intheadjacent resolution cellsinthetimedomain. Whentheproductofthebandwidth Bandthepulsewidthrisgreaterthanunity,asina pulsecompression radar,thelossisdetermined bytheproduct MBTratherthanM.Thus,a lossof1.0dBcorresponds toMBt='100.Theratioofthebandwidths Mtherefore canbe unitywhenBrislargeenough.73Bothcoded-pulse waveforms8sandfrequency-modulated waveforms havebeenconsidered forpuls~compression radarwithCFAR.86 ThebenefitsofalargeBrforCFARcanalsobeobtained withouttransmitting apulse­ compression waveform.87Aconventional pulsewaveform canbetransmitted, andonrecep­ tionthereceived signalpassedthroughadispersive delay'line (apulseexpansion network) that spreadsthesignaloveraduration T.Theoutputofthedispersive filterishardlimitedandfed toaseconddispersive delaylinewithacharacteristic inversetothefirst.Thermsnoisepower attheoutputissmallerthanthepeakpowerfromapointtargetbythefactorBT.Adelection threshold issetsomewhere withinthisrangeofpossible amplitude toallowpointtargetsthat arelargerthanthebackground to,bedetected. Thisdispersive CFARmaybeplacedeither beforeorafterthematched filter.' Thelog-FTC receiver described inSec.'13.8hasCFARproperties whenthebackground hasaRayleigh probability densityfunction. 
 It is seen that  the signals returned would differ by ∆G2(q ). This results in imperfect cancellation due  to scanning. The average effect on the improvement factor can be obtained by integrat - ing this differential effect ∆G2(q ) over the main beams:  IG d G T Gpscan= + −− −∫ ∫2 00 002| ( ) | | ( ) ( )θθ θθθ θ θ θ θ| |2dθforsingle-delaycancellatio n  (3.14 a)  IG d G T Gpscan= + −− −∫ ∫6 200 002| ( ) | | ( ) (θθ θθθ θ θ θ θ) ) ( ) | + −G T dp θ θ θ2fordoubl e-delaycancellatio n n      (3.14 b) where q0 = null of main beam  G (q ) = two-way voltage pattern ch03.indd   14 12/15/07   6:03:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 TRAFFIC CONTROL RADARS v  0ROC )%%%  VOL     PP n  *UNE    2 * 0URDY ET AL  h2ADAR SIGNAL PROCESSING v ,INCOLN ,ABORATORY *OURNAL  VOL   .O      2 * -C!ULAY  h!  THEORY FOR OPTIMUM -4)  DIGITAL SIGNAL PROCESSING v -)4 ,INCOLN ,ABORATORY   ,EXINGTON  -!  2EPORT NO 
 R .. and lJ. Gold: "Theory and Application of Digital Signal Processing," Prentice-Hall. 
 3.2. Experimental Results In this section, a simulated experiment of a point target in Additive White Gaussian Noise (AWGN) is presented to show the results that can be obtained using the SVD decomposition; here, all the information inherently present in the raw data ﬁle is exploited; in the successive subsections, results of the focusing procedure are presented for real SAR raw data. 3.2.1. 
 2R. Haus1., W., and R. A. 
 2AYLEIGH DENSITY  &OR .     COMPARISON OF THE OPTIMAL BINARY INTEGRATOR  OUT OF    A NOTHER  BINARY INTEGRATOR  OUT OF    AND THE MOVING 
 • The increased use of 3D radar for military applications. • The introduction of the ultralow-sidelobe antenna for airborne pulse doppler radar and, later, for ECCM. • The replacement of the parabolic reflector antenna with the planar- aperture array antenna for 3D radar, ultralow-sidelobe antennas, and airborne radar. 
  AND DIFFERENCE 
 CIVIL MARINE RADAR  22.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 Most small craft radars now being sold include the option of a chart underlay facility  as a relatively low-cost option. In general, these use unofficial vector chart data, issued  by specialist private companies. This data is more affordable than ENCs and is directed  to this particular market. 
 Synchronization and other housekeeping data are sent over  telephone lines. Signal and data processing is PC-based. ( after J. 
 /Ê"Ê"* 
 However, electrically thewaveguide iskept sealed astightly aspossible inorder to prevent the general level ofleakage power intheclosed container being high enough tointerfere with AFC operation. The sealing isdone by woven metal gaskets atevery junction. Ashort section offlexible corrugated waveguide next tothe magnetron absorbs the dimensional tolerances and permits allparts tobebolted together tightly without strain. 
 14.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 Radar Cross Section Eugene F. Knott Tomorrow’s Research 14.1 INTRODUCTION A radar detects or tracks a target, and sometimes can classify it, only because there  is an echo signal. It is, therefore, critical in the design and operation of radars to be  able to quantify or otherwise describe the echo, especially in terms of such target  characteristics as size, shape, and orientation. 
 !K & DYE E EPIK Y KH #Y K KH= 
 JAMMING ENERGY RATIO CONSTANT .EVERTHELESS  IN PRACTICE  THE  EFFECT OF MAIN 
 asinglefrequency sOll1cwhcre inthcmiddIeofIhcmicrowave bandmustheselected asacompromisc (Shand.or pcrhapsCorLhands).Thecompromise frequency mightthusbehigherthanwouldbcdesired forsearcltandlowerthandesiredfortracking. Thcresll1tisthatasingle-frequency, multifunc­ tionradarmightnotbcasefficient asseparate radarsoperating atseparate frequcncies, each optimizcd tofulfillasingle,dedicated function.Itisconceivable insomecircumstances that Iworadars,oncoptimizcd forsurvcillalH:e andthcotherfortrack,willpcrform beller,beless COSIly,andtakclesstotalspacethanasinglemultifunction radar. Thecautionregarding thedrawbacks ofamultifunction radarisespecially trueofaircraft­ sUiveillance radar.However, iftheparticular application issuchthattheoptimum frequency forsearchisthesameasthatfortracking, itismorelikelythatamultifunction arrayfi.ldar wouldhavemeritoverseparate radars.Suchseemstobethecaseforsatellite surveillance wherethesamefrequency (UHF)seemsdesirable forbothsearchandtrack,asinthe AN/FPS-85. 
         INT   MAX MAX MAX   M M6 6"I WHERE    I       )N THIS EQUATION   6"I I  02&L IS THE BLIND VELOCITY FOR THE  ITH #0) 4HE POS 
 (ILL "OOK #OMPANY     - ) 3KOLNIK   )NTRODUCTION TO 2ADAR 3YSTEMS   RD %D  .EW 9ORK -C'RAW 
 DENCE HAVE BEEN KNOWN FOR DECADES &IGURE  SHOWS THESE &OR LIKE 
 The power wasted inbackswing da’mping israrely more than afew per cent ofthe total useful power output ofthe pulser, and the duration of thebackswing isseldom greater than 2to10.psec. Some pulsing circuits produce asecondary forward pulse, V~,,which can cause trouble by feebly exciting the magnetron togive afew microwatt ofpower. In many applications this would causeco noconcern because ofthe much ().1 ,A’ greater amplitude ofthemain power?T,I pulse. 
 155–168, March 1986. 28. B. 
 One conventiondeﬁnes beam width as the angular width between points at which the ﬁeldstrength is 71 percent of its maximum value. Expressed in terms of powerratio, this convention deﬁnes beam width as the angular width betweenHALF-POWER POINTS. The other convention deﬁnes beam width as theangular width between points at which the ﬁeld strength is 50 percent of itsmaximum value. 
 RANGE PARAMETERS  SUCH AS SIGNAL 
 HORIZON PATHS  DECREASED HORIZON PATHS  AND DISTORTIONS IN SIMPLE SURFACE REFECTION AND MULTIPATH INTERFERENCE 3UBREFRACTION  )F THE MOTIONS OF THE ATMOSPHERE PRODUCE A SITUATION WHERE THE  TEMPERATURE AND HUMIDITY DISTRIBUTION CREATE AN INCREASING VALUE OF  . WITH HEIGHT   THE WAVE PATH WOULD ACTUALLY BEND UPWARD AND THE ENERGY WOULD TRAVEL AWAY FROM THE %ARTH 4HIS IS TERMED  SUBREFRACTION !LTHOUGH THIS SITUATION OCCURS INFREQUENTLY  IN NATURE  IT STILL MUST BE CONSIDERED WHEN ASSESSING ELECTROMAGNETIC SYSTEMS PER 
 J. White: Low-Frequency Approach to Target Identification, Proc.  IEEE, vol. 
 la 0.6  L.  .~ 0.4 -0 £ 0.2 Clutter  spectrum Single  cancellation  I I  I  I I /  I  I  Double  cancellation---""\  \  \ Clutter lo/dover~  / " I '- / \  I \  I \  I \  I \  I \  O~'..LL~~~~---1..~~~~_L~....,CLL~~~~........L~~~~_..l-J-D,,"""":......J...~~  0 fp =Yr 2 Ip  Frequency  Figure 4.10 Relative frequency response of the single-delay-line canceler (solid curve) a9d the double­ delay-line canceler (dashed curve). Shaded area represents clutter spectrum. 
 SYNCHRONICITY PRESENTS ITS OWN PROBLEMS FOR OCEAN 
 Iftherefractive index nand theabsorption index Kare introduced bythefamiliar relation n+iK=16L, (15) Eq. (14) can berewritten ~=?t+~K-Ji n+iK+p”(16) Let usnow examine the behavior ofanabsorber ofthe first kind in which the internal reflection occurs from ametal surface atthe plane z=–d.Itwill beassumed that .2issmall compared ton’. The calculation ofthe resultant reflection can bemade bysumming the emergent rays and adding this sum tothewave reflected from theplane z=O. 
 LINE  OR BY A TRACKER 
 One of the two foci of the hyperbola is the real focal point of the  system. The Feed is located at this point, which can be at the vertex or the parabola or in front  of it. The other focus of the hyperbola is a virtual focal point and is located at the rocus of the  parabolic surface. 
 M. Goldstein and H. A. 
 Department of Defense (DoD) and other federal  government agencies, U.S. private industry, their foreign counterparts, and by  private individuals. AREPS grew out of an urgent military operational requirement for radar perfor - mance and propagation modeling within a terrain effects dominated environment. 
 The above discussion shows that ingeneral the cathode-ray tube imposes asevere restriction inrange resolution onany but the fastest sweeps. Itistherefore apparent that unless fast sweeps aretobeused there isnopoint ingoing toextreme bandwidths inthe receiver. In most cases the receiver bandwidth need not besogreat astoimpair seriously the signal-to-noise discrimination. 
 Enlargement of the shear-wave-generated eddy in Frame A. The ﬂight and look direction of ENVISAT-1 ASAR are indicated by black arrows. Two wind vectors are shown as red arrows. 
 µÕ>Ì 7>ÞiÊ °Ê*>ÌÌiÀÃ 3PACE AND .AVAL 7ARFARE 3YSTEMS #ENTER  !TMOSPHERIC 0ROPAGATION "RANCH ÓÈ°£Ê  /," 1 /"  0ARALLELING THE DEVELOPMENT OF RADAR TECHNOLOGY IS THE DEVELOPMENT OF THE RADAR EQUA 
 However, it may he  shown that the average beat frequency measured over a modulation cycle, when substituted  into Eq. (3.11) yields the correct value of target range. Any reasonable-shape modulation  waveform can be used to measure the range, provided the average beat frequcncy is  measured. 
 Freedom from warping is insured bythe use ofhot-rolled steel and byannealing. The corner- reflector blocks areprecision-ground pieces, but ofashape familiar toa tool-making shop. These reflectors bolt without gaskets tothemain end plates beneath thevisible housings. 
 BASED 3!2S DIFFERS IN SEVERAL KEY REGARDS 4HE HIGHLIGHTS ARE REVIEWED HERE &OR MORE COMPLETE COVERAGE  SEE THE STANDARD REFERENCES   ! SIMPLIFIED INTRODUC 
 The resulting ampli - tude steps will cause quantization lobes (Section 13.6).FIGURE 13.33  Combination of subarrays to form sum and difference channels: ( a) combining opposite  subarrays and ( b) combining subarrays after amplification ch13.indd   50 12/17/07   2:41:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 Roth: Ferrite Phase Shirters in Rectangular Waveguide, J. Applied  Phrsics, vol. 25. 
 STANT   AS ILLUSTRATED IN &IGURE  )N GENERAL  A FAST !'# IS RECOMMENDED BECAUSE IT REDUCES THE ADDITIONAL NOISE  TERM ALLOWED BY SLOW !'# AND THE POSSIBILITY OF LARGER RMS TRACKING ERRORS  WHICH CAN BE CONSIDERABLY GREATER THAN THE ANGLE NOISE WITH A FAST !'# !S PREVIOUSLY DISCUSSED  ANGLE NOISE IS SIGNIFICANT  MAINLY AT MEDIUM AND CLOSE RANGE WHERE TARGET ANGLE RATES ARE GREATEST !S SEEN IN &IGURE  A TRACKING LAG OF ONLY ONE 
 S.: Characteristics of Triangular Lattice Arrays. Proc. IEEE, vol. 
  
 The p  mode oscillates at a single frequency,  but the other modes can oscillate at two different frequencies so that the magnetron  can oscillate at N - 1 different frequencies.) Coaxial Magnetron Life . The power that can be produced by a magnetron depends  on its size. A larger size means more resonators, which makes it more difficult to  separate the various modes of oscillation in a conventional magnetron. 
 Evenifthelow-noise deviceitselfisoflarge dynamic range,therecanbeareduction ofthedynamic rangeofthereceiver ascompared toa receiver withamixerasitsfront-end. Dynamic rangeisusuallydefined astheratioofthe maximum signalthatcanbehandled tothesmallest signalcapable ofbeingdetected. The smallest signalistheminimum detectable signalasdetermined byreceiver noise,and themaximum signalisthatwhichcausesaspecified degreeofintermodulation oraspecified deviation fromlinearity (usually IdB)oftheoutput-vs.-input curve. 
 This is seen clearly in Fig. 13.3a and b, which com- pares the grazing-angle dependence of X-band clutter data for wind speeds in the neighborhood of 15 kn obtained from four sources: NRL 4FR24 (these are mean results for upwind directions and include the antenna corrections mentioned above), aircraft measurements by Masuko et al.29 (also in the upwind direction), and summaries of the older data (pre-1970) taken from books on radar systems by Skolnik2 and Nathanson.3 The discrepancies between the different data sets can be accounted for, at least in part, as follows. The older data set was based on published measurements from various sources, and since there is no specification of wind direction, it may be assumed that it represents some kind of average of upwind, downwind, and crosswind directions. 
 Zhu, and W. Hong, “SAR activities in P. R. 
 RANGE INFORMATION IS PLOTTED '02 IS GENERALLY USED IN SUCH A WAY AS TO GENERATE A SEQUENCE OF ! 
 Element-level DBF requires a digital receiver, which consists of a downconverter and  an ADC, at each element. Subarray-level DBF requires a digital receiver at each sub - array. A fully digital array, which has DBF at the element level, allows for multiple,  simultaneous independent beams. 
 In addition, other users in the spectrum must be observed continuously and operating frequencies selected to avoid interfer- ence. In the context of transmission-path assessments for frequency selection, real time is measured as that interval in which there are no important changes in the ionosphere. The magnitude and doppler distribution of the earth-surf ace backscatter is a major factor in setting system dynamic-range and signal-processing characteris- tics. 
 K. S. Cole and R. 
 IT-3,  pp. 10-18, March, 1957.  24. 
 #&!2 #LUTTER MAPS WORK WELL FOR STATIONARY RADARS OPERATING AT FIXED FREQUENCIES  BUT ARE LESS EFFECTIVE FOR OTHER RADARS 4HE #! 
 W.. Jr., and K. M. 
 S(co) = C,£2aT5 exp [-C2(^)4] (24.3) where 5 = waveheight squared per hertz a) = water-wave angular frequency v = wind speed C1, C2 = constants The exponential term approximates the decay in the spectrum above the wind maximum velocity. The co~5 asymptotic term is a feature of major interest and use. This saturation effect suggests that the sea echo can provide an amplitude reference, and an important consequence is that with such a reference path losses may be estimated. 
 Wallace, “The interpretation of the fluctuating echo for randomly distributed scatterers,” Pt.  II, Can. J. 
 Thustheyareofinterestfor determining elevalion angleinJDradar.Inonemethod,66 afrequency-scan beamisrapidly sweplthrough Iheangular regionofinterest, andthereceived signalispassedthrough abank ofmatched filters,eachfillercorresponding toadilTerent angular direction. Thiswasmen­ IionedinSec.RA. Theotherisareceive-only method thatusesareceiving arraywithmixersandlocal oscillalors (LOs),arranged soastoprovideNseparate receiving beamsfixedinspace (Fig.R.29).Eachmixerissupplied withadifferent LOfrequency. 
 P. Coleman: Microwave Stepped-index Luneburg Lenses, I RE Trans .•  vol. A P-6. 
 RECEIVE OPERATION USUALLY IS NOT AS GOOD AS CAN BE OBTAINED WITH AN -4) SYSTEM THAT USES A POWER AMPLIFIER AS THE TRANSMITTER !UTOMATIC FREQUENCY CONTROL !&#  IS OFTEN EMPLOYED TO KEEP THE RECEIVER TUNED  TO THE FREQUENCY OF THE TRANSMITTER SINCE THE MAGNETRON FREQUENCY CAN SLOWLY DRIFT WITH CHANGES IN AMBIENT TEMPERATURE AND SELF 
 It is usually a collection of capacitors known as a ctrl)czclror bntlh  The hard-tube modulator permits more flexibility and precision than the line-type modu-  lator. It is readily capable of operating at various pulse widths and various pulse rcpetltion  frequencies, and it can generate closely spaced pulses. The hard-tube modulator, however, IS  generally of greater complexity and weight than a line-type modulator. 
 50. Senf, H. R.: Electronic Antenna Scanning, Proc. 
 LEVEL $"& IS FREQUENTLY PURSUED BECAUSE IT  REQUIRES FAR FEWER DIGITAL RECEIVERS (OWEVER  SUBARRAYS ARE NOT THE BEST CHOICE OF ARRAY ARCHITECTURES FOR A GIVEN NUMBER OF $/& IN AN ADAPTIVE ARRAY   )N SUBARRAY $"&  THE  MAIN BEAM OF EACH SUBARRAY MUST BE ALIGNED WITH THE MAIN 
 The eﬀectiveness of the proposed high precision imaging method is veriﬁed by experiment in Section 6. In Section 7, we discuss the concluding remarks. 2. 
 In the use of such a physical linear array, signals are fed simultaneously to each of the elements of the array. Similarly, when the array is used as a receiver, the elements receive signals simultaneously; in both the transmitting and the receiv- ing modes, waveguide or other transmission-line interconnections are used, and interference phenomena are exploited to get an effective radiation pattern. The radiation pattern of a linear array is the product of two quantities if the . 
 Angle (deg) Noise (dBW)• = R4th Loss. = R4th + Lo = Frequency* = El. Angle ^ 1 deg.- = NoiseJULSSN= 1OTlME = IBGMTLOCATION 38.65 N LAT 76.53 W LON BEARING= 90.00 DEC • = R4th Loss• = R4th -I- L 0 = Frequency* = El. 
 The simulation is performed by considering the inﬂuence of different spectral index from 3 to 5, and CkLis set as 1034to present a signiﬁcant demonstration. Based on the theoretical analysis in Section 3, the TFTPCF serious degenerates with the increasing of spectral index. The decrease of TFTPCF will lead to the signal decorrelation and the azimuth defocusing. 
 The output of a matched-filter receiver is  16INTRODUCTION TORADAR SYSTEMS Otherstatistical factorswhichdonotappearexplicitly inEq.(2.1)butwhichhaveaneffecton theradarperformance arethemeteorological conditions alongthepropagation pathandthe performance oftheradaroperator, ifoneisemployed. Thestatistical natureoftheseseveral parameters doesnotallowthemaximum radarrangetobedescribed byasinglenumber. Its specification mustincludeastatement oftheprobability thattheradarwilldetectacertain typeoftargetataparticular range. 
 TIAL TO REDUCING THE VULNERABILITY OF 3!2 TO JAMMERS 4HE SUSCEPTIBILITY TO INTERCEPT SIGNALS FROM 3!2 AND VULNERABILITY TO JAMMING ARE DESCRIBED IN 'OJ  ! SIMULATED  NOISE JAMMING PRODUCES STRIPES ON THE 3!2 IMAGES THAT DEMONSTRATE THE EFFECTIVE 
 RANGE WEATHER  4HE CURRENT STATE 
 Memo. Rept. 2500, September 1972. 
 isnotaspronounced inthecaseoftheroundearth:theminimaare notasdeepnorarethemaxima asgreatsinceawavereRected fromacurvedsurfaceismore divergent thanonerenected fromaplane.Theotherregionofinterest isthatwhichliesjust heyond theinterference regionbelowtheradarlineofsightandisthediffraction. orthe shadow. region.Hereradarsignalsarerapidlyattenuated. 
 FREQUENCY 
 687–704, June 1974. 49. D. 
 If monostatic RCS data is also available as a function of frequency, the monostatic curve for/sec (P/2), where/is the bistatic frequency, is used toH PLANE E PLANENORMALIZED BISTATIC RCSaB/7ra2 (dB) . estimate the bistatic RCS at /. As outlined earlier, this correction is usually small. 
 Pre-Doppler, Beam-Space STAP.  The first type of transformation to be consid - ered is spatially oriented, resulting in beam-space STAP architectures. This transfor - mation is typically required for many large apertures. 
 Eng .,  vol. OE-5, pp. 211–215, October 1980. 
 We can now build reliable radar equipment whose principal performance limitation arises because the earth isround; the major improvements tobelooked forinthe use ofradar over the next few years will lie,forthemost part, notinthecategory oftechnical radar design, but inthe field offitting the entire radar system, including its operational organization, tothe detailed needs oftheuse and theuser. EXTERNAL AIDS TORADAR USE 7.2. Aids toIndividual Navigation.-The most frequent and impor- tant use made ofradar isasanaid toairand sea navigation. 
  $AVIES E, 
 POWER 474S FOR RADAR SYSTEMS 4HE SEVERAL DIFFERENT VOLTAGES NEEDED FOR THE DEPRESSED COLLECTORS ADD COMPLEXITY TO THE HIGH 
 The corribiri~tion of a linear array arid parabolic cylinder can also generate a pencil beam.  -Plie eridfire array is ;I special case of tlie linear or the planar array when the beam is  cfirected alorig the array. Eridlire linear arrays have not been widely used in radar applications. 
 Gandhi and S. A. Kassam, “Analysis of CFAR processors in nonhomogeneous background,”  IEEE Transactions on Aerospace and Electronic Systems,  vol. 
 Swath widths achieved  are as much as five times the nominal strip-map width, which is considerably larger  than the conventional ambiguity constraint would allow. Normally, the trade-off in  azimuth resolution is balanced with a corresponding compromise in range resolution,  leaving excess range bandwidth that may be converted into looks. Starting from a  100-km swath 25-m × 25-m 4-look system, a reasonable ScanSAR mode could be  500-km swath, 100-m × 100-m × 8-looks, with no increase in average data rate or  transmitted power. 
 74. Wilson, J. W., and W. 
 8.17 Curves of probability of detection versus signal-to-noise ratio for the cell- averaging CFAR, ratio detectors, log integrator, and binary integrator: Rayleigh, pulse- to-pulse fluctuations, probability of false alarm = 10~6, and maximum jamming-to-noise ratio = 20 dB. (From Ref. 25.) is more difficult to implement. 
 More recently, the Canada Centre for Remote Sensing (CCRS) has made numerous airborne scatterometer measurements,17 especially over sea ice. The Environmental Research Institute of Michigan (ERIM),18 CCRS, the European Space Agency (ESA),19 and the Jet Propulsion Laboratory (JPL)20 used imaging synthetic aperture radars (SARs) for some scattering mea- surements, but most were not well calibrated. Results of most of these measurements are summarized in Ulaby, Moore, and Fung.21 More complete summaries of the earlier work and near-grazing studies are in Long.22 Many applications summaries are also in the "Manual of Remote Sensing."23 Readers requiring more detailed information should consult these books. 
       
 663–674,  1999. 39. B. 
 no~/05,"Radar-Present andFuture," Oct. n25.1973.pp.112J17. 3.1.(iclnovatch. 
 TO 
 Lawson. J. Land G. 
 Sidelobe Canceler (SLC) System. The objective of the SLC is to suppress high duty cycle and noiselike interferences (e.g., SOJ) received through the sidelobes of the radar. This is accomplished by equipping the radar with an array of auxiliary antennas used to adaptively estimate the direction of arrival and the power of the jammers and, subsequently, to modify the receiving pattern of the radar antenna to place nulls in the jammers' directions. 
 93. Shelton, J. W.: Fast Fourier Transform and Butler Matrices, Proc. 
 It may also  include more complex clutter-mapping processes. All of this is attempting to create  a constant false alarm rate across the radar display. Since the radar is sited on a mov - ing platform, subject to complex dynamics, difficulties arise with clutter mapping. 
 Unfortunately, the two are at cdds with one another. The  more slowly the radar antenna scans, the more pulses will be available for integration and the  better the detection capability. On the other hand, a stow scan rate means a longer time  hetwcerl looks at the target. 
 Figure 1. Schematic diagram of imaging geometry for idealized anticyclonic eddy [ 11]. In order to interpret and evaluate the effects of the radar look direction and wind ﬁeld conditions on SAR eddy imaging, numerical imaging simulations can serve as an effective tool for the systematical investigation of brightness variations of shear-wave-generated eddies. 
 39. Hsizo. J. 
 66.Schultz, F.V..R.C.Burgener. andS.King:Measurement oftheRadarCross-section ofaMan./'w('. IRE.vol.4o,pp.4764XI. 
 The ambiguity diagram for a single rectangular pulse of sine wave is  shown in Fig. 11.9. Contours for constant values of doppler frequency shift (velocity) are  shown in Fig. 
 The exact solution for the scatter - ing by a conducting sphere is known as the Mie series4 and is shown in Figure 14.2. Note that the chart is split roughly into three regions. In the Rayleigh region  below  ka < 1, the RCS rises with the fourth power of the sphere radius, an echo dependence  characteristic of electrically small bodies, whether spherical or not. 
 FIGURE 13.4  Radiation pattern of two isotropic radiators ch13.indd   10 12/17/07   2:39:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 Chelton (ed.), Corvallis,  Oregon: Oregon State University, 2001. 82. R. 
 Birrer, E. M. Bracalante, G. 
 (a) Vertical polarization, (b) Horizontal polarization. (Based on data from Masuko et al.,29 NRL 4FR,21 Skolnik,2 and Nathanson.3)GRAZING ANGLE (degrees) (a)GRAZING ANGLE (degrees) (b)MASUKOETAL. SKOLNIK (S = NATHANSONMASUKO ET AL. 
 Sherman, S. M.: Complex Indicated Angles Applied to Unresolved Radar Targets and Multipath.  IEEE Trans. 
 8. J. N. 
   -4) 2!$!2  Ó°n )N ADDITION TO THE hGHOSTv PROBLEM  MULTIPLE RANGE AMBIGUITIES LEAD TO TARGETS HAVING  TO COMPETE WITH CLUTTER AT ALL RANGES )N PARTICULAR  TARGETS AT LONG DISTANCES HAVE TO COMPETE WITH STRONG CLUTTER RETURNS IN THE FIRST  OR SEVERAL  RANGE INTERVALS "ECAUSE OF THE GHOSTING PROBLEM  IN ORDER TO MINIMIZE RANGE AMBIGUITIES WHILE  RETAINING ADEQUATE DOPPLER SPACE  2& FREQUENCIES OF  -(Z OR LOWER ARE BEST SUITED FOR THE 36# UNWANTED TARGET DISCRIMINATION TECHNIQUE 2ANGE 
 '"in ttie. normal superheterodyne receiver by using  an intermediate frequericyJ~igh;eito o~render. th'e flic~er noise small compared with the  normal receiver noise'::'Thk- resultgifron{the' inverse. 
 Figure 4shows the transversal proﬁle of section LL’ in the test area (see the red solid line at the bottom of Figure 3b), where 2% and 0.82% represent the gradient, and the average thickness of the soft soil layer in this cross-section is 4.5 m. From the transversal distribution along the test highway, the main distribution characteristics of the geotechnical layer are as follows: ground layer distribution is pseudo-viscosity plain ﬁll and a quaternary system of brand-new sea-land cross stratum. The surface quaternary is mainly composed of silty soil and mealy sand, deposited by sea and land, including mucky clay, silty soil, and mealy sand. 
 THE 
 PARABOLOID CONCEPT IS A CONVENIENT METHOD OF ANALYZING THE RADIA 
 They are  often so large that they might not be completely removed by MTI. Thus it is not uncommon  for MTI radar to have at its output many fixed point-scatterers that must be recognized so as  not to be confused with desired targets.  Probability density function for land clutter. 
 In addition,Airborne Maritime Surveillance Radar, Volume 1 2-4. with the advent of LRASV broadside antennas a method for rapidly switching between broadside arrays and homing arrays became essential. Initially, this was achieved by the operator unplugging one set of antennas and plugging in the new set.This was too slow in practice and very tiring for the operator if it had to be repeatedly undertaken. 
 TO 
 9.18). The body ofthe array consists ofafixed 16-ft extruded aluminum channel and amovable 16-ft aluminum plate which together form aguide ofvariable width (Fig. 9.19). 
 This provides a  three-dimensional "image" or the target since the azimuth and elevation of each scatterer is  given along with the range. Figure 5.20 is an example of the type of radar image that might be  obtained with an aircraft. This technique not only improved significantly the tracking accur­ acy as compared with a longer pulse conventional tracker, hut its unique measurement  properties provide additional capabilities. 
   '2/5.$ %#(/  £È°£x 4HE SPECTRUM OF FADING CAN BE CALCULATED BY A SLIGHT REARRANGEMENT OF THE RADAR  EQUATION %Q   4HUS  IF  7RFD  IS THE POWER RECEIVED BETWEEN FREQUENCIES  FD AND  FD   DFD  THE RADAR EQUATION BECOMES  7FD F0'! D ! 2RD DTTR     PS )LLUMINATEDAREAA BETWEEN ANDFF D FDT T R DD DDF 0' ! 2  ¯   PS 
 11.8b agreat many stubs, extending both ways from thetwo-wire line, have been added, still with- outaffecting thepropagation ofthefrequency inquestion. InFig. 11.8c thestubs have coalesced into arectangular tube which looks like awave- Wide. 
 Itisnotsurprising thattheachievement ofalltheseproperties cannotalwaysbefullysatisfied simultaneously. Antenna designisanimportant partofthe successful realization ofagoodmonopulse radar. Theuniform aperture illumination maximizes theaperture efficiency and,hence,the directive gain.Theaperture illumination thatmaximizes theslopeofthedifference patternis thelinearillumination function withoddsymmetry aboutthecenteroftheaperture.23Not onlydobothoftheseaperture illuminations produce patterns withrelatively highsidelobes, buttheycannotbereadilygenerated bythesimplefour-horn feed.Independent controlofthe sumandthedifference patterns isrequired inordertoobtainsimultaneously theoptimum patterns. 
 Consequently, if the number of pulses per beam width is small, the angular accuracy will be poor. For instance, if pulses are separated by 0.5 beamwidth, a(0) is bounded by 0.14 beam width. However, improved accuracy can be obtained by using the ampli- tudes of the radar returns. 
 BAND MEASUREMENTS BY 6 7 0IDGEON  Ú !MERICAN 'EOPHYSICAL 5NION   . 
 H. Anderson and J. L. 
  OR STEPPED 
 The larger the value  of m, the more constrained will be the fluctuations. The limit of m equal to infinity corresponds  to the nonfluctuating target.  The chi-square distribution is a mathematical model used to represent the statistics of thc  fluctuating radar cross section. 
 1% INTRODUCTION TO RADAR SYSTEMS  (4) load susceptance. The first two parameters are related to the input side of the tube, while  the last two are related to the output side. In most magnetrons the magnetic field is fixed by the  tube designer and may not be a variable the radar designer has under his control. 
 89. A. H. 
 STATE MODULES IN PHASED ARRAY RADARS 4O A GREAT EXTENT  IT CAN BE COMPENSATED FOR BY USING MORE PULSE COM 
 An SAR image registration method based on pyramid model. In Proceedings of the 2016 CIE International Conference on Radar (RADAR), Guangzhou, China, 10–13 October 2016; pp. 1–5. 
 Jll," R. C. Hansen (ed.), Academic Press, New York, 1966, pp. 
 COMPRESSED .,&- TEND TO INCREASE COMPARED TO THOSE OF THE ,&- &IGURE   SHOWN LATER IN THIS SECTION  AND 4ABLE  ILLUSTRATE THIS BEHAVIOR FOR A TYPICAL .,&- PULSE 4HIS CHARACTERISTIC OF THE .,&- WAVEFORM SOMETIMES NECESSITATES PROCESSING USING  MULTIPLE MATCHED FILTERS OFFSET IN DOPPLER SHIFT TO ACHIEVE THE REQUIRED TIME SIDELOBE LEVEL "ECAUSE OF THE DOPPLER SENSITIVITY OF THE AMBIGUITY FUNCTION  THE NONLINEAR FRE 
 37. Spaulding, A. D., and J. 
 CIES AND   VARIES WITH DIRECTION  BEING GREATEST FOR SEAS RUNNING TOWARD OR AWAY FROM THE RADAR 4HE DOPPLER SPECTRUM OF THE ECHO HAS SHARP VARIATIONS THAT REQUIRE CAREFUL PROCESSING TO PRESERVE 4HE RECEIVER AND PROCESSOR MUST BE ABLE TO HANDLE BOTH THE HIGH 
  D"  4HE  RESULT IS THAT THIS ARRAY HAS A MEAN FLOOR OF RANDOM SIDELOBES THAT ON THE AVERAGE  IS  D" BELOW THE PEAK OF THE BEAM )T ALSO ILLUSTRATES THAT TO ACHIEVE LOW SIDELOBES .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°Î£ VERY TIGHT TOLERANCES ARE REQUIRED 4HE AMPLITUDE OF  VV IS EQUIVALENT TO A TOTAL  AMPLITUDE STANDARD DEVIATION OF  D" RMS 4HE TOTAL RMS PHASE ERROR IS  n )T  SHOULD BE NOTED THAT THERE ARE NUMEROUS SOURCES OF PHASE AND AMPLITUDE ERRORS THAT ARE INDUCED BY THE PHASE SHIFTERS  THE FEED NETWORK  THE RADIATING ELEMENTS  AND THE MECHANICAL STRUCTURE 4HE TASK OF BUILDING A LOW 
 RELATED INFORMATION ON SHIPBORNE  NAVIGATIONAL  DISPLAYS v  2ESOLUTION  -3#    )NTERNATIONAL  -ARITIME  /RGANIZATION   ,ONDON    )NTERNATIONAL (YDOGRAPHIC /RGANIZATION  WWWIHOSHOMFR  h4RANSFER STANDARDS FOR DIGITAL HYDROGRAPHIC DATA v 0UBLICATION 3 
 Acknowledgments: The authors would like to thank all the anonymous reviewers for their valuable comments to improve the quality of this paper. Conﬂicts of Interest: The authors declare no conﬂict of interest. References 1. 
 6.2  Reciprocity  ........................................................  6.2  Gain, Directivity, and Effective Aperture  .............  6.3  Radiation Patterns  ............................................. 
 After the bunched electron beam delivers its RF power to the otrtput cavity, the electrons  are removed by the collector electrode which is at, or sligt~tly below, the potential of the  interaction structure. From 50 to 80 percent of the d-c input power might be converted to heat  in typical linear-beam tubes, and. most of this heat appears at the collector. 
 Stark. L.: A Helical Line Scanner for Beam Steering a Linear Array, IRE Trans.. vol. 
 IT-6, pp. 400-408, June, 1960.  37. 
 DRIVEN SEA  CLUTTER 8 BAND  HORIZONTAL POLARIZATION  WIND SPEED  KT  RAIN RATE  MMH  FROM * 0 (ANSEN  . £x°Ó{  2!$!2 (!.$"//+  4HE PRODUCTION OF SEA CLUTTER BY RAIN FALLING ON A hCALMv SURFACE IN THE ABSENCE  OF WIND WAS ALSO INVESTIGATED BY (ANSEN  WITH THE RESULTS SHOWN IN &IGURE   ! HIGH 
 RATE $/! MEASUREMENTS AT USEFUL RANGES  TRIANGULATION IS SELDOM CONSIDERED FOR OTHER APPLICATIONS #ONCEPTS  DATA  AND EXPRESSIONS DEVELOPED FOR BISTATIC RADARS O FTEN APPLY TO MULTI 
 Changes in transmitter frequency affecttheechosignalsinthetwodirections equallyandaretherefore canceled whentakingthedifference frequency. Another methodofachieving thenecessary isolation inadoppler-navigation radaris withasinusoidal frequency-modulated CWsystem.Byfrequency-modulating 'thetransmis­ sion,theleakagesignalmaybereducedrelativetothesignalfromthegroundbyextracting a harmonic ofthemodulating frequency andtakingadvantage ofoneofthehigher-order Bessel functions asdescribed intheprevious section.Ithasbeenclaimedthatadoppler navigation systembasedonthisprinciple canprovide 150dBofisolation, theamount necessary to operateataltitudes of50,000ft.49 Thefrequency bandfrom13.25to13.4GHzhasbeenallocated forairborne doppler navigation radar,butsuchradarsmayalsooperatewithinthebandfrom8.75to8.85MHz. Thedoppler navigator overlandcanprovideameasurement ofgroundspeedwitha standard deviation offrom0.13to0.5percent. 
 16  Frequency -diversity Radar  ................................ ................................ ................................ 
 . Ó°{n  2!$!2 (!.$"//+  4HE FILTER COEFFICIENTS ARE   A    
 IRON 
 1^* Type II SBR includes the earth and planetary resources radar used for mapping, scatterometers, altimeters, and subsurface probing.5"9 Side- . looking SAR techniques are typical of mapping radars such as those used on the Seasat satellite in June 1978 and the Shuttle in November 1981 with the Shuttle Imaging Radar-A (SIR-A). Type III SBR includes the large phased array surveillance radar proposed for multimission defense, air traffic control, and disarmament functions.10"14 Type ISBR. 
 56--58, 1953.  38. Peeler, G. 
 C. B. Sharp and R. 
 Figure 4.24. Schematic block diagram of ASV Mk. VIC [ 6].Airborne Maritime Surveillance Radar, Volume 1 4-21. 
 I. Stein, “Bistatic radar applications in passive systems,” Journal of Electronic Defense , 13(3),  pp. 55–61, March 1990. 
 In order to get a well-focused image, the absolute values of the phase errors caused by the spatial variance of a2and a3should be less thanπ 4andπ 8, as expressed by (16) and (17), respectively. /vextendsingle/vextendsingle/vextendsingle/vextendsingle/vextendsinglea 21(fdc−fdc,cen)/parenleftbiggBa 2/parenrightbigg2 π/vextendsingle/vextendsingle/vextendsingle/vextendsingle/vextendsingle<π 4,/vextendsingle/vextendsingle/vextendsingle/vextendsingle/vextendsinglea 22(fdc−fdc,cen)2/parenleftbiggBa 2/parenrightbigg2 π/vextendsingle/vextendsingle/vextendsingle/vextendsingle/vextendsingle<π 4, (16) /vextendsingle/vextendsingle/vextendsingle/vextendsingle/vextendsinglea31(fdc−fdc,cen)/parenleftbiggBa 2/parenrightbigg3 π/vextendsingle/vextendsingle/vextendsingle/vextendsingle/vextendsingle<π 8, (17) where Bais the Doppler width of the target. 4.2. 
 This brightness variation of the shear-wave-generated eddy depends on the radar look direction and wind ﬁeld. By analyzing two airborne SAR images of the same eddy under two orthogonal ﬂight tracks, Lyzenga [ 11] found that under two orthogonal radar look directions, the eddy spirals show the opposite brightness variation. Johannessen [ 12] also found that the changes in the radar look direction result in varying NRCS along eddy spirals. 
 16. Y. Nemoto, H. 
 Curry, and J. T. Francis: An Adaptive Threshold System for  Nonstationary Noise Backgrounds, IEEE Trans., vol. 
 84. Hanson, V. G., and H. 
 SIGNAL HORN IS USED  AS A COMPROMISE (OWEVER  THE FIVE 
 Continuous waveforms (CW)alsocanbeusedbytakingadvantage ofthedoppler frequency shiftto separate thereceived echofromthetransmitted signalandtheechoesfromstationary clutter. Unmodulated CWwaveforms donotmeasure range,butarangemeasurement canbemade byapplying eitherfrequency- orphase-modulation. 1.2THESIMPLE FORMOFTHERADAR EQUATION Theradarequation relatestherangeofaradartothecharacteristics ofthetransmitter, receiver. 
 Curve A applies to a chemical recorder which makes a  permanent record, and curve B applies to an intensity modulated B-scope of long persistence.  (The chemical recorder has been of more use in sonar than in radar.) The integration improve-  ment was found to be from 2.2 to 2.5 dB per doubling of the number of pulses, which is  consistent with the computations for the theoretical integration improvement obtained by  Mar~urn~~ for ideal postdetection integration. The results for the chemical recorder (curve A)  are slightly better than the B-scope (curve B) due to the imperfect memory of the cathode-ray  tube B-scope as compared with the permanent memory of the chemical recorder. 
  KKSCAT INC    &OR THE SIMPLE CASE OF BACKSCATTER AT GRAZING INCIDENCE  THE GEOMETRY FOR MONO 
 A compromise usually  must be made between good smoothing of the random measurement errors (requiring narrow  handwidth) and rapid response to maneuvering targets (requiring wide bandwidth). Another  criterion for selecting the cx.-fJ coefficients is based on the best linear track fitted to the radar  data in a least squares sense. This gives the values of a and f3 as 74  2(211 -1) a=------- 11(11 + 1) 6  /3= n(n + 1)  where II is the number of the scan or target observation (n > 2). 
 131. Schoenenberger, J. G., et al.: Design and Implementation of a UHF Band Bistatic Ra- dar Receiver, IEE Colloq. 
 At the  lower frequencies, the array might be a collection of dipoles or Yagis, and at the higher  frequencies the array might consist of slotted waveguides.  Linear array with frequency scan,. The frequency-scanned, linear array feeding a parabolic  cylinder or a planar array of slotted waveguides has seen wide application as a 3D  air-surveillance radar. 
 Parashar, S. K., R. M. 
 The aerial inputs were successively connected over 180 °± 2.5 °of rotation and the outputs connected over 170 –175 °intervals. Switch units type 25 and 42 were used for the Pye receivers. The two switch sections were on a common shaft rotated at16–20 rps. 
 F. Turner, “Wide angle lens for line source applications,” IEEE Trans .,   vol. AP-11, pp. 
 BASED RADARS  WHICH HAS SINCE BEEN VALIDATED AS A STANDARD TECHNIQUE  3!33  THE 3EASAT 
 3CAN  OR 473  IS TO USE THE NORMAL SEARCH MODE WITH &- OR  MULTIPLE 
 POWER SIGNAL IS APPLIED TO THE INPU T OF THE FIRST CAVITY AND  APPEARS AT THE  INTERACTION GAP 4HOSE ELECTRONS IN THE BEAM THAT ARRIVE AT THE FIRST  INTERACTION GAP WHEN THE INPUT SIGNAL VOLTAGE IS AT A MAXIMUM THE POSITIVE PEAK OF THE SINE WAVE  ARE SPEEDED UP COMPARED TO THOSE ELECTRONS THAT ARRIVE AT THE GAP WHEN THE INPUT SIGNAL VOLTAGE IS A MINIMUM THE NEGATIVE TROUGH OF THE SINE WAVE   &)'52%  2EPRESENTATION OF THE PRINCIPAL PARTS OF A THREE 
 The same result occurs when the system design is based on a required range coverage in the presence of standoff jammers (rather than just thermal noise). For detection of a target carrying a self-screening jammer, the range equation becomes R2 a (Pr x Ar) I (Pj x Aj) (4.2) where P1. and Ar are the power and aperture of the radar and Pj and Aj are those of the jammer. 
 105  11.6.1 Luneburg Lenses ................................................................................................... 105  11.6.2 Corner Reflectors .................................................................................................. 106  11.7 RCS of Complex Objects .............................................................................................. 
 ROW BEAM -34 RADAR v 0LANET 3PACE 3CI  VOL   PP n    0 "ROWN AND * *ONES  h! DETERMINATION OF THE STRENGTHS OF THE SPORADIC RADIO 
 ”Were wetotrace thepath ofan initially horizontal ray atthis level, wewould find itcurving downward just enough tokeep upwith the curvature ofthe earth, and therefore maintaining constant height. Farther down inthe duct, where the gradient isstronger, itwould bepossible foraray launched ataslight upward inclination tobebent back tothe surface again and thus to proceed byaseries ofbounces, trapped asitwere, within theduct. From this temptingly graphic picture ofpropagation within aduct itiseasy todraw false conclusions. 
 ORDER (ASELGROVE EQUATIONS REMAINS  THE MOST WIDELY USED #OLEMAN HAS DEVELOPED AN ALTERNATIVE IMPLEMENTATION.   (& /6%2 
  D"  WITH 3.2  y  D"  BUT COULD NOT IMAGE hFLATLANDv  PERHAPS DESERT  AT R   y  
 GET RESPONSE  ENVIRONMENTAL CONDITIONS  INTERFERENCE  AND JAMMING &URTHER  WIDEBAND  PROCESSING CAN GIVE FINE RANGE RESOLUTION 0HASED ARRAYS HAVE THE POTENTIAL OF OPERATING OVER VERY WIDE BANDWIDTHS 4HE  HIGH END OF THE FREQUENCY BAND IS LIMITED BY THE PHYSICAL SIZE OF THE ELEMENTS   WHICH MUST BE SPACED CLOSE ENOUGH IN THE ARRAY TO AVOID THE GENERATION OF GRATING LOBES SEE 3ECTION   &OR WIDE INSTANTANEOUS BANDWIDTH RATHER THAN TUNABLE BANDWIDTH   TIME DELAYS HAVE TO BE ADDED TO PREVENT THE BEAM FROM BEING SCANNED AS THE FREQUENCY IS CHANGED 4HE IMPEDANCE OF THE RADIATING ELEMENT AT THE APERTURE WITH CLOSELY SPACED  ELEMENTS  IS APPROXIMATELY INDEPENDENT OF FREQUENCY  BUT THE ELEMENT MUST BE MATCHED OVER THE WIDE BANDWIDTH 4HIS IS DIFFICULT TO ACHIEVE WITHOUT EXCITING HARMFUL SURFACE WAVES WHEN SCANNING .EVERTHELESS  MATCHING WITH OCTAVE BAND 
 INTEGRATOR OUTPUT 7ITH ADVANCES IN DIGITAL TECHNOLOGY  IT HAS BECOME POSSIBLE AND PRACTICAL TO GENERATE  WAVEFORMS DIRECTLY AT )& OR 2& CARRIER FREQUENCIES ON A SINGLE INTEGRATED CIRCUIT CHIP  4HIS  TECHNIQUE IS CALLED  $IRECT $IGITAL 3YNTHESIS   OR $$3  AND INVOLVES GENERATING WAVEFORMS AT  &)'52%     $IGITAL WAVEFORM GENERATION BLOCK DIAGRAM .   05,3% #/-02%33)/. 2!$!2   n°Ó HIGH SAMPLING RATES AND FILTERING THE OUTPUT 4HESE DEVICES GENERATE THE WAVEFORM BY ACCU 
 The various beam positions can be obtained by sampling the output at the proper time. In  Fig. 8.29 one beam sampling channel is illustrated. 
 Publ. 20, February 1966. 2. 
 B. Kunz and D. G. 
 H. Ulander and P. O. 
 Torres, “Cancellation of diffuse jammer multipath by an airborne adaptive  radar,” IEEE Trans ., vol. AES–31, no. 2, pp. 
 it is often preceded by a medium-power traveling-wave tube. This  combination takes advantage of the best qualities of both tube types. The TWT provities high  gain, and the CFA allows high power to be obtained with high efficiency, good plrase stability,  and low voltage.20  The characteristics of a CFA are illustrated by the Varian SFD-257, a forward-wave tube  used in the final high-power amplifier stage of the transmitter chain in the AN/MPS-36  C-band range-instrumentation tracking radar.'"he SFD-257 operates over the frcqi~ency  range 5.4 to 5.7 GHz with a peak power of 1 MW, 0.001 duty cycle, and an efficiency of over 50  percent. 
 12.Susskind,c.:"TheBirthoftheGoldenCockerel: TheDevelopment ofRadar,"inpreparation. 13.Price,A.:"Instruments ofDarkness," Macdonald andJanes,London, 1977. 14.Lobanov, M.M.:"IzProshlovo Radiolokatzii" (OutofthePastofRadar),Military Publisher ofthe Ministry ofDefense, USSR,Moscow, 1969. 
 F. Earl, “FMCW waveform generator requirements for ionospheric over-the-horizon radar,”  Radio Science , vol. 33, pp. 
 466-473, May 1978. 27. Emara, E. 
 could bedoubled bydoubling thelinear dimensions oftheantenna. But thelatter step would atthesame time reduce thebeamwidth byafactor of2and asweshall seeinSec. 2“11that this indirectly affects Sti.. 
 Normally,  there are two or three distinct layers such that signals may partially penetrate the lower  layers to be reflected by a higher layer. As a consequence, the relationship between  the range to a target and the measured echo time delay becomes multivalued, with  unknown parameters such as layer heights that must be estimated by various tech - niques as described later in this chapter. To illustrate the operating principles of a skywave radar, Figure 20.3 presents a  map showing multiple surveillance tasks assigned to a hypothetical radar with 360 °  azimuthal coverage. 
 RENT  BUT THE POWER NEEDED TO DRIVE THE MODULATING ANODE IS SMALL BECAUSE THE CURRENT INTERCEPTED BY THE MODULATING ANODE IS VERY SMALL 6ERY HIGH 
 King, R. W. P., and T. 
 6.46  Ground and Shipboard Radomes  .......................  6.47 . This page has been reformatted by Knovel to provide easier navigation. 
 Allpossible radar systems canthen beclassified bydescrib- ingthetype ofmodulation and theusemade oftheresulting information. Asaspecific example ofthese general remarks, letustake avery simple radar system which consists, asshown inFig. 5.1, ofanr-fpower source, anantenna, arectifier, ahigh-pass filter, anindicator, and a 127. 
 Frequency is 1300 MHz (L band) with linear  polarization. V V = vertical polarization,  H H = horizontal polarization. {b) Eleva­ tion-variation nose-on (azimuth = O") (c)  Elevation-variation tail-on {azimuth =  180°). 
 Several time lags in series combine to produce TS. These are the track-loop time constant, the noise-filter time constant, and the autopilot-airframe response time. The antenna track-loop time constant can be eliminated as a contribute? in certain configurations (LOS or LOS rate reconstruction12). 
 However, there are other instances in which the target's  position in4tlirce dirncrisiolls   nil st be known. In tliis section, radar methods for obtaining the  elevatioti angle or heiglit of a target will be discussed briefly. The height of a target above  the surface of the earth may be derived from the measurement of elevation angle and range. 
 TOR DESIGN VARY IN ACCORDANCE WITH THE REFLECTOR SYSTEM AND THE PLATFORM (OWEVER   0,!4&/2- $2)6%3 2%&,%#4/2 !.4%..! -%#(!.)#!, $%3)'. 
 OSPHERE IS ENORMOUS  AND INCLUDES NOT ONLY THOSE ARISING NATURALLY BUT ALSO MANY INDUCED PHENOMENA SUCH AS THOSE RESULTING FROM GROUND 
 Tuley, Radar Cross Section , 2nd Ed., Raleigh, NC:  SciTech, 2004. 27. E. 
 Turner, “Wide angle microwave lens for line source application,” IEEE  Trans ., vol. AP-11, pp. 623–632, November 1963. 
 Thus neither  the range nor the velocity can be determined without knowledge of the other.  This limitation can be overcome by transmitting a second FM pulse whose slope on the  ambiguity diagram is different from that of Fig. 11.12. 
 G.: Radio Telegraphy, Proc. IRE, vol. 10, no. 
 Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 22.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 22.9 VALIDATION TESTING The factors affecting the range performance of a radar system are well known, and  increasingly sophisticated design methodologies have greatly improved the detection  of all forms of radar. The final proof, however, is how the radar actually performs at  sea. 
 In such situations the  MTI signal processor must have the capability of placing separate rejection notches at the  dopplcr frequencies of the clutter. 7 uz  4.12 OTHER TYPES OF MTI  Two-frequency MTI. 78· 79 The first blind speed of an MTI radar is inversely proportional to the  carrier frequency, as described by Eq. 
 The line impedance seen atthemagnetron istherefore arapidly varying function offrequency. Ifatacertain frequency thephase happens tobesuch that thevariation ofreactance ofthe line with frequency ismore rapid than that ofthe magnetron itself, and ofopposite sign, acondition results where themag- netron has nostable frequency. Inanother, favorable, phase the mag- netron isstabilized. 
 592-593, Dec. 13, 1973.  51. 
 FREQUENCY INTERFERENCE IS FILTERED IN SUBSEQUENT STAGES OF THE RECEIVER  STRONG INTERFERENCE SIGNALS CAN CAUSE CLUTTER RETURNS IN THE ,.! TO BE DISTORTED  DEGRADING THE EFFECTIVENESS OF DOPPLER FILTERING AND CREATING FALSE ALARMS 4HIS PHENOMENON IS DIFFICULT TO ISOLATE AS THE CAUSE OF FALSE ALARMS IN SUCH RADARS OWING TO THE NONREPETITIVE CHARACTER OF MANY . 
 IRE, vol. 36,  pp. 180-196. 
 197–203. 192. L. 
 Elevation constants are similar to those for the azimuth sys- tem. The range tracker may be an inertialess electronic system with a double in- tegration in the tracking loop. This is called a Type II system25 with a Kv = <», causing velocity lag to be zero. 
 11 15, 1976. pp. 589 582, IEEE Cat. 
 5.10 and 10.7). is another important  evelopment whose basic theory was known for some time, but whose practical realization  ad to await advances in digital technology. The principle of ADT was demonstrated in the  early 1950s. 
 50. L. W. 
 C'. Currie. arid M. 
 The complexity of the adaptive  rilccllariizatiorl and the speed of colivergence limit the practical utility of the large adaptive  array. The fewer the adjustable elements the more practical is the adaptive array.  One potential application of adaptive array antennas is for airborne surveillance radai. 
 E.: Advances in Radar Signal Processing, IEEE Electro '76, Boston, Mass, May 11-14,  1976.  44. Drury. 
 ~1).Forlarge2na/A.,themdar crosssectionapproaches theopticalcrosssectionna2•Inbetween theopticalandtheRayleigh regionistheMie,orresonance, region.Thecrosssectionisoscillatory withfrequency within thisregion.Themaximum valueis5.6dBgreaterthantheopticalvalue,whilethevalueofthe firstnullis5.5dBbelowtheopticalvalue.(Thetheoretical valuesofthemaximaandminima mayvaryaccording tothemethodofcalculation employed.) Thebehavior oftheradarcross sectionsofothersimplereflecting objectsasafunctionoffrequency issimilartothatofthe sphere. 15-25 Sincethesphereisaspherenomatterfromwhataspectitisviewed,itscrosssectionwill notbeaspect-sensitive. Thecrosssectionofotherobjects,however, willdependuponthe direction asviewedbytheradar. 
 This is accomplished in tlie radar  system diagramed in Fig. 4.5 by generating the transmitted signal from rile coho reference  sigtial. The function of the stalo is to provide the necessary frequency translation from the IF  to the transmitted (Kf;) frequency. 
 PASS  FILTERING  4HE SPECTRUM OF FADING AT ANOTHER RANGE OR VERTICAL ANGLE  IS DIFFERENT  IN ACCORD WITH %Q  &OR MANY PURPOSES  THE NUMBER OF  INDEPENDENT SAMPLES IS IMPORTANT BECAUSE THESE  MAY BE TREATED BY USING THE ELEMENTARY STATISTICS OF UNCORRELATED SAMPLES &OR CONTINU 
 LENGTH FEED IS NOT IN USE  THE FEED NETWORK WILL  PRODUCE A CHANGE IN PHASE WITH FREQUENCY )N SOME CASES  SUCH AS 2OTMAN LENS  OR  EQUAL 
 (% &' (%&' (%&'(% &'(% &'(%&'(%&'    #   "!  )  $       .   2!$!2 $)')4!, 3)'.!, 02/#%33).'   Óx°£Ç -ULTI 
 Other Optimal Codes. Table 10.4 lists the total number of optimal binary codes for all N up through 40 and gives one of the codes for each N. As an ex- ample, the minimum peak sidelobe for a 19-bit code is 2. 
 16.7 Improvement factor / versus normalized doppler offset CT^ as a function of clutter spectrum width crc.FREQUENCY FIG. 16.6 Effect of doppler-offset error; fr = PRF.CLUTTER FILTER DOUBLE DELAY SINGLE DELAYIMPROVEMENT FACTOR (dB) . maximum. 
 C.. and M. II. 
 WAVE PATHS AND BY PROPAGATION EFFECTS DUE TO THE IONOSPHERE  4HE CLUTTER SPECTRUM TENDS TO FILL IN AROUND AND BETWEEN THE LINES AS THE WIND PICKS UP &OR HORIZONTAL POLARIZATION WHICH IS POSSIBLE ONLY FOR SKY 
 φi(1,MN) ............ φ i(pq,1)φi(pq,2)... φi(pq,MN) ............ 
 Battan20 devotes three full pages of his book to the listing of dozens of Z-R relation - ships derived by investigators at various locations throughout the world, for various  weather conditions, and in all seasons of the year. The fact that no universal expression  can be applied to all weather situations is not surprising when one notes that rainfall  drop-size distributions are highly variable. For many conditions, the drop-size distri - bution can be represented by an exponential function  N(D) = N0 e –ΛD (19.48) where N0 and Λ are constants and ΛD0 = 3.67 where D0 is the median drop diameter. 
 The curves arerather arbitrarily drawn, and only their general trend issignificant. Not every upward. 10 INTRODUCTION [SEC. 
 In a search radar, however, the radiation intensity throughout the entire beam is of interest,  not just that at the beam center. A number of hits are received as the antenna scans by each  target. The detection decision is based on the energy from all.the hits received and not just on  the energy received when the ,center of the beam' illuminates the target. 
 One type of storage device that has been used in scan converters is a double-ended  storage tube with two electron guns, one on each side of a charge-storage surface. 32 The  radar output is written in PPI format by one electron gun on one side of the charge-storage  surface. The second gun, on the other side of the storage surface, reads the stored charge  pattern with a TV raster. 
 Range-ambiguity resolution in high PRF is performed by  modulating the transmitted signal and observing the phase shift of the modulation  on the return echo. Modulation methods include varying the PRF, either continu - ously or in discrete steps; varying the RF carrier, with either linear or sinusoidal  FM; or some form of pulse modulation such as pulse-width modulation (PWM),  pulse-position modulation (PPM), or pulse-amplitude modulation (PAM). Of these  modulation techniques, PWM and PPM may have large errors because of clipping  of the received modulation by eclipsing or straddling (discussed in Section 4.6), and  PAM is difficult to mechanize in both the transmitter and the receiver. 
 ch24.indd   67 12/19/07   6:01:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 TEROMETERS v IN  0ROC )NT 'EOSCIENCE AND 2EMOTE 3ENSING 3YMP )'!233    %DINBURGH   3EPTEMBER n    PP n 0UBLISHED BY .OORDWIJK  .ETHERLANDS %UROPEAN 3PACE !GENCY  %34%#  . £x°{Ó  2!$!2 (!.$"//+    ( 'OLDSTEIN  h&REQUENCY DEPENDENCE OF THE PROPERTIES OF SEA ECHO v  0HYS 2EV  VOL     PP n     ! ( 3CHOOLEY  h3OME LIMITING CASES OF RADAR SEA CLUTTER NOISE v  0ROC  )2%  VOL      PP n     7 3 !MENT  h&ORWARD AND BACKSCATTERING BY CERTAIN ROUGH SURFACES v  4RANS )2%  VOL !0 
 According to Nathanson, 33 the discrete frequency-shift waveforms are preferable instead  of linear FM when the pulse-compression ratio and the signal bandwidth are large. The  resulting thumbtack ambiguity diagram means there will be no range-doppler coupling to  cause erroneous measurements. The order in which the discrete frequencies are transmitted  can be varied so that each radar can have its own code, and interference between radars will be  reduced. 
 ch13.indd   33 12/17/07   2:40:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 G.; A very early RADAR pioneer: Christian Hülsmeyer in 1904; RADIO  BYGONES No. 54, Aug./Sept. 1998 . 
 DETECTED SAMPLES  EITHER LINEAR OR SQUARE 
 Such surface ﬁlms alter the sea surface tension by smoothing ripples and cause the diminishing of NRCS. The third Sensors 2019 ,19, 1529; doi:10.3390/s19071529 www.mdpi.com/journal/sensors 311. Sensors 2019 ,19, 1529 eddy manifestation mechanism is one possible due to variations in the wind ﬁeld caused by changes in the atmospheric boundary layer across an oceanic temperature front [ 8,9,13,14]. 
 In selecting a storage medium one must consider the rate at which information must be recorded, the amount of data to be recorded, and the rate at which the . FIG. 21.6 STAR-I radar imagery, lower Detroit River. 
 and a pulse repetition frequency of several hundred pulses per second.  The waveform generated by the transmitter travels via a transmission line to the antenna,  where it is radiated into space. A single antenna is generally used for both transmitting and  receiving. 
 It also applies to the  distribution of the round-off (quantizing) error in numerical computations and in analog-to-  digital converters.  The constant k may be found by applying Eq. (2.10); that is,  The average value of x is  This result could have been determined by inspection. 
 The output of the matched filter was shown in Sec. 10.2 to be equal to the cross correla­ tion between the received signal and the transmitted signal [Eq. (10.18)]. 
 OF 
 (b)Eleva­ tion-variation nose-on (azimuth =0°)(e) Elevation-variation tail-on (azimuth = 180°).(FromOlinandQueen.lO)A;180o--o--o::::=--: 0._______0--0 10203080100120 140 160 180 Az,mu'h aspectangle(deg) (a) 4o,------------,60 (blA~0' 0__ 0__°::::::::_0--0o J::----..1O-----;;2"'0-~3~0~~- 40 °0!c---·-:-;1O~-·-;;-20r;-----,- 3"0:------::-40 Elevatian aspectangle(deg) (e)40 30 N !I200.c 0 CD :2 b10 00 crosssectionthanmicrowaves becausethedimensions ofthescattering objectsarecompar­ abletothewavelength andproduce resonance effects. Anexample ofth~measured radarcrosssectionofalargeship(16,000tons)isshownin Fig.2.21.Theaspectisatgrazingincidence. Whenaverages ofthecrosssectionaretaken abouttheportandstarboard bowandquarteraspectsofanumberofships(omitting thepeak atbroadside), asimpleempirical expression isobtained forthemedian(50thpercentile) value ofthecrosssection: (2.38) °0k-----..,2=0-~40=------=60,.-----=8c;;:0--:,=00;,--·1"'2;;-0- ..,4""0-'-..,6=-;;0:--....-;!,80 Az'mulhaspectangle(deg) (a)40,----------, 40,--------:0=----, <£"30 ~o-g20 CD ~30 20~?-----_. 
 TION OF RECEIVER 
 TION MAY BE TOTALLY SUPPRESSED /NE EXAMPLE OF THE POTENTIALLY SERIOUS CONSEQUENCES OF VERY STRONG ABSORPTION IS THE IMPACT IT MIGHT HAVE ON AVIATION STORM AVOIDANCE  RADARS  MOST OF WHICH ARE IN THE  
 FIG. 11.24 The geometric optics RCS of a doubly curved surface de- pends on the principal radii of curvature at the specular point. The specular point is that point on the surface where the surface normal points toward the radar. 
 This technique has sometimes been called METRRA, which stands for Metal Reradiat­ ing Radar.48 Most solid, mechanical, metal-to-metal bonds and properly made solder joints  do not show nonlinear effects. However, ir there is no molecular contact between the metals,  and the space between them is small (of the order of 100 A), then there can be discernible  nonlinear effects. Such effects are noted with loose metal-to-metal contacts. 
 TACTICAL AIR COMMANDS 235 tion functions. Off-center PPI scopes are provided forthe chief con- troller and thedeputy controllers, thelatter sitting along thesides ofthe shelter. Atthe right ofthe shelter, near the plotting board, sits the supervisor, who isresponsible forthetechnical operation oftheradar set. 
 DELAY -4) RADAR SYSTEMS FALL CONSIDERABLY SHORT OF THE PREDICTED PERFORMANCE 4HIS OCCURS BECAUSE THE )& BANDPASS LIMITERS HAVE BEEN USED TO SUPPRESS THE ENERGY OF THE RESIDUE SPIKES THAT ARE CAUSED BY THE LIMITING ACTION ,ATER IN THIS SECTION  IT IS SHOWN THAT THE USE OF A BINARY DETECTION SCHEME  INSTEAD OF A DRASTIC REDUCTION OF THE LIMIT LEVEL  CAN BE USED TO MAINTAIN A CLUTTER REJECTION PERFORMANCE CLOSE TO LINEAR THEORY PREDICTION IN THE RESOLUTION CELLS WHERE CLUTTER LIMITING OCCUR !N EXAMPLE OF HOW LIMITING THE  DYNAMIC RANGE ADJUSTS THE RESIDU E IS SHOWN IN THE  -4) 00) PHOTOGRAPHS SHOWN IN &IGURE  4HE RANGE RINGS ARE AT  
 WHITE NOISE WILL BIAS THE SPECTRAL MOMENT ESTIMATES &OR MANY PAST OPERATIONAL RADARS  THE PULSE 
 OF 
 62. S. R. 
 4.1. Spaceborne SAR Data The spaceborne SAR data contains data from two kinds of satellite system. One is TerraSAR-X system images, the other is Gaofeng-3 system images. 
   CATION WILL OFTEN BE ADEQUATE (OWEVER  MORE COMPLEX TRACKING P ROBLEMS REQUIRE VARI 
 The resistance ofthe carbon pile ranges from 2to60ohms.’ Its electrical rating isbased ontherate ofallowable heat dissipation, and is given inwatts. The unit often used onaircraft inverters israted at 35watts. Smaller inverters, notably the Eclipse 100- and 250-va units, useasmaller regulator rated at20watts, while 2500-va inverters use a 75-watt regulator, ofthe same physical size asthe 35-watt unit, but with fins toincrease the rate ofheat dissipation. 
 15.6,  waveheight is proportional to the square of the wind speed, so in the Gulf Stream,  for example, with a current of 4 kt flowing north, a 15-kt northerly blowing against  the current will raise a sea three times as high as a 15-kt southerly blowing with the  current. Even with no wind, the presence of strong current shears  can produce highly  agitated surfaces. Shipboard observers have reported bands of roaring breakers pass - ing by on an otherwise-smooth surface, presumably produced by powerful surface- current shears associated with large-amplitude internal waves.78 In a more subtle way,  modulated currents are held responsible for synthetic aperture radar (SAR) images  that contain the expression of bottom topography produced by the Bernoulli Effect in  shallow waters.79 In each of the examples cited above, the current produces a change  in the surface roughness, which can be expected to give rise to a change in sea clutter  cross section. 
 In the proposed KA-DBS framework, the DBS imaging model for WAS radar is constructed and the cross-range resolution is analyzed. Since the radar illuminates the imaging scene continuously through the scanning movement of the antenna, there is strong spatial coherence between adjacent pulses. Based on this fact, forward and backward pulse information can be predicted, and the equivalent number of pulses in each coherent processing interval (CPI) will be doubled based on the autoregressive (AR) technique by taking advantage of the spatial continuity property of echoes. 
 Rept .  ERL 110-ITS 78, U.S. Department of Commerce, 1969. 
 TIONS A MEASURE OF %##- EFFECTIVENESS SHOULD INVOLVE THE WHOLE WEAPON SYSTEM IN WHICH THE RADAR OPERATES 4HE MEASURE OF EFFECTIVENESS SHOULD BE EXPRESSED IN TERMS OF THE NUMBER OF ATTACKERS DESTROYED OR THE PROBABILITY OF RADAR SURVIVAL 2EFERENCES IN THE LITERATURE ATTEMPT TO ASSESS THE %##- EFFICACY n  3IMULATION IS ANOTHER MEANS TO ASSESS THE %##- BENEFITS IN RADAR AND WEAPON  SYSTEMS !N ADVANTAGE OF THIS APPROACH RESIDES IN THE CAPABILITY TO ARTIFICIALLY  GENERATE DIFFERENT TYPES OF THREATS AND TO LOOK AT THE RADAR  AND WEAPON SYSTEM  REACTIONS (OWEVER  THE SIMULATION OF SUCH A COMPLEX SYSTEM IS A DIFFICULT  TIME 
 SISTENT WITH OTHER CONSTRAINTS )T HAS BEEN CONSIDERED FOR VERY HIGH 
 For volurne dis-  tributed clutter a cross sectiori per r~liit volilnic. or reflectivity. is defined as  wliere n, 111 this C~IFC is t11c radar cross section from tile volume V,  /  13.2 SURI'ACE-CLU'I'I'EU RADAR EQUATIONS  Corisider the geometry of Fig. 
 12. J. Cooley and J. 
 IRE, vol. 48, p. 1164, June, 1960. 
 - !CTIVE PHASED ARRAY ANTENNAS MUST BE CALIBRATED IN ORDER TO ENSURE THAT THE RADIA 
 19.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 is 1 MW at S band and 50 KW at Ka band. The pulse widths are approximately 1 µs.   The PRF is typically 1000 s–1 at S band and a few times larger at Ka band. 
 29. H. K. 
 ARRAYS IS  REQUIRED THIS MAY BE THE REASON FOR THE LACK OF APPLICATION OF THIS TECHNIQUE TO PRACTI 
 19. Wright, J. W.: A New Model for Sea Clutter, IEEE Trans., vol. 
 Anominal valueforthe minimum range(orskipdistance) isaboutWOOkm. Thebackscatter fromtheearth'ssurface isgenerally manyordersofmagnitude larger thantheechofromdesiredmovingtargets.ThusHFradarmustemploysomeformofdoppler processing suchasMTJ,pulse-doppler, FM-CW, orCWradartoseparate desin.:dmoving targetsfromclutter.Theequivalent ofahigh-pass filtermustbeusedtodetectmoving airr.raft andmissilesandrejectstationary surfaceclutter.Thedetection ofshipsrequires moresophis­ ticatedprocessing sincetherelatively lowvelocity ofshipsproduces doppler-frequency shifts comparable tothoseofthesea(whichisalsoamoving target). Eventhoughtheradarcross sectionofshipsisoftengreaterthan thatofaircraft, longerobservation timesarerequired to provide sufficient resolution indoppler frequency. 
 18. Rarton, D. K.: " Radars, vol. 
 ! -02& 5SUALLY FEWER 02&S ARE USED FOUR OR FIVE ARE TYPICAL  ! RANGE AMBIGU 
 From a theoretical point of view, new mathematical structures of pulsar signal models and space object’s imaging algorithms based on the atomic clock’s stability and wide bandwidth of pulsars’ emissions will be developed. From a practical point of view, this work will motivate the development of new highly sensitive technologies to detect pulsars reemissions of asteroids and other nonidentiﬁed objects. The usage of steady and stable pulsar emissions for object navigation and imaging purposes is not limited by time and space which is the main advantage of this kind of stellar technology. 
 APPROVED CHART RADAR MUST ALSO BE ABLE TO ACCEPT THESE UPDATES #HARTS AND THEIR UPDATES ARE LOADED BY #$ 
 ORDER TERM  IN %Q  CAN BE INTERPRETED AS hDOUBLE 
 TO 
 2.52  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 2.10 CLUTTER FILTER BANK DESIGN As discussed in Section 2.2, the MTD uses a waveform consisting of coherent pro - cessing intervals (CPIs) of N pulses, all at the same PRF and RF frequency. The PRF  and possibly the RF are changed from one CPI to the next. With this constraint, only  finite-impulse-response (FIR) filter designs are realistic candidates for the filter bank  design. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20  s w d ww ( ) ( ( ))( ( ) = − − − =±∑ 26 04 1πk S m k k mB  scat inc + + ∫∫26 04 1 1 2 22 1 1 2 2 1πk m m S m S m mΓ( , ) ( ) ( )   k k k k , ,m m g m g d d21 1 1 2 2 1 2= ±∑ − −( ) d w k k k k  (20.6)  where  kinc and  kscat are the incident and scattered radio wave vectors, k k0=| | inc,  w is the doppler frequency, S( )k is the sea directional wave spectrum, d (.) is the  Dirac delta function, and the Bragg frequency wB is given by wBg k k = −  scat inc. 
 Timing. Because modulator rise times differ, triggers to each amplifier stage must usually be separately adjusted to provide proper synchronization without excessive wasted beam energy. In CFA chains, allowance must also be made for the pulse-width shrinkage that occurs because of the necessary overlap of RF drive, as noted in Sec. 
 TED POWER 643 RADAR HEADS ARE USUALLY NOT OPERATOR CONFIGURABLE BECAUSE A NUMBER OF OPERATORS CAN TYPICALLY BE USING DATA FROM ONE HEAD. ÓÓ°Îä  2!$!2 (!.$"//+  4HERE ARE MORE OPPORTUNITIES TO ENHANCE PERFORMANCE BECAUSE OF THE FIXED ANTENNA  POSITION FOR INSTANCE  SEA CLUTTER MAPPING BECOMES EASIER BECAUSE THE ANTENNA IS NOT  ON A MOVING PLATFORM !LSO  THE CLUTTER CONDITIONS CAN BE LESS VARIABLE BECAUSE OF THE RESTRICTED GEOGRAPHICAL AREA OF OPERATION  AND THERE ARE NO DEGRADATIONS IN THE ACCU 
 689-691, September 1974. 33. Frank, R. 
 The need for improved performance led to the high power ASV Mk. VI, described in chapter 4. During WWII, all centimetric ASV radars operated with a wavelength of 9 cm (often referred to at the time as 10 cm ASV), but H2S Mk. 
 (a)Side view; (b)top view; (c) bottom view,. 462 THE RECEIVIXG SYSTEJ-RADAR RECh’11’ERS [%c. 129 12.9. 
 COUPLING PROBLEMS &)'52%    &IVE 
 Receivers then increase in complexity through tactical ESM to the full ELINT (intelligence-gathering) capability. The specification of an ideal ELINT receiver for today's applications demands an instantaneous frequency coverage of 0.01 to 40 GHz, a sensitivity of better than -60 dBm, an instantaneous dynamic range greater than 60 dB, and a frequency resolution of 1 to 5 MHz. A diversity of sig- nals, such as pulsed, CW, frequency-agile, PRI-agile, and intrapulse-modulated . 
 MAX  THAT APPEARS IN THE AMBIGUOUS 
 The core area and thus theweight ofthetransformer asawhole can bedecreased asfincreases because of the corresponding reduction inB~,,.Bygoing from 60cpsto400 cps, savings intransformer weight of50per cent areattainable. Core area cannot bemuch further reduced byincreasing jfrom 400 cpsto800cps, asiron losses perpound forconstant B-,increase more than linearly with frequency. Weight savings of10per cent atmost are obtainable by this change infrequency. 
 The sliding spotlight mode provides an operational solution to meet the requirement of high imaging resolution in P-band SAR design. Unfortunately, the space-borne P-band SAR will be inevitably deteriorated by the ionospheric scintillation. Compared with the stripmap mode, the sliding spotlight SAR will suffer more degradation when operating in the scintillation active regions due to its long integration time and complex imaging geometry. 
 ROTATED 3#  )4  ETC  CRYSTAL RESONATORS ARE ABLE TO SUPPORT HIGHER POWER LEVELS THAN SINGLE AXIS CRYSTALS 4HIS ENABLES THEM TO ACHIEVE LOWER PHASE NOISE AND IMPROVED VIBRATION IMMUNITY DUE TO PROPERTIES UNIQUE TO THE PARTICULAR AXIS OF ROTATION &REQUENCY MULTIPLICATION OF THESE 6(& SOURCES IS OFTEN USED TO GENERATE THE RADAR 2& FREQUENCIES REQUIRED HOWEVER  THIS MULTIPLICATION PROCESS RESULTS IN INCREASE IN PHASE NOISE PERFORMANCE BY  LOG -  D" WHERE  - IS THE MULTIPLICATION FACTOR !  VARIETY OF OTHER SOURCE TECHNOLOGIES  SUCH AS 3URFACE !COUSTIC  7AVE 3!7  OSCILLA 
 3.3. It is a tracking radar as welt as an  illuminator since it must be able to follow the target as it travels through space. The doppler ) . 
 Thus the choice of  T, /T2 is a compromise between the value of the first blind speed and the depth of the nulls  within the filter pass band. The depth of the nulls can be reduced and the first blind speed  increased by operating with more than two interpulse periods. Figure 4.17 shows the response  of a five-pulse stagger (four periods) that might be used with a long-range air traffic control  radar.' In this example the periods are in the ratio 25 : 30 : 27 : 31 and the first blind speed is  28.25 times that of a constant prf waveform with the same average period. 
 If the point moves by δxand δyin time δt, then, according to the brightness constancy constraint: dI dt=0. (2) This can also be stated as: I(r+δr,t+δt)= I(r,t), (3) where r=( x,y,1)Tand r+δr=( x+δx,y+δy,1)T. However, the brightness constancy constraint is restrictive. 
 THE 
 TYPE OBJECT DETECTION APPARATUS v 53 0ATENT  .OVEMBER     + 2 2OTH  - % !USTIN  $ * &REDIANI  ' ( +NITTEL  AND ! 6 -RSTIK  h4HE +IERNAN REENTRY  MEASUREMENTS SYSTEM ON +WAJALEIN !TOLL v 4HE ,INCOLN ,ABORATORY 4ECHNICAL *OURNAL  VOL     NO     $ 2 "ROMAGHIM AND * 0 0ERRY  h! WIDEBAND LINEAR FM RAMP GENERATOR FOR THE LONG 
 It employs a relatively large vacuum tube and the  entire display is often big and can be expensive. The cost is not simply the tube itself, which is  usually modest, but the various circuits needed to display the desired information and provide  the operator with flexibility. The amount of information that can be displayed is limited by the  spot size, which in a high-performance display is less than 0.1 percent of the screen diameter. 
 Ferretti, A.; Prati, C.; Rocca, F. Permanent scatterers in SAR Interferometry. IEEE T rans. 
 The critical parts ofthe circuit areRIC1,the delay potentiometer, and the various supply volt- ages. Apentode with sharp suppressor cutoff, such asthe miniature 6AS6, can besubstituted forthe more complicated multiple-grid tube with equally good results. The phantastron can also beused asafree- ranning relaxation oscillator. 
 154INTRODUCTION TORADAR SYSTEMS N eo 10:.:: e'~ ~Q f I I It/")....., I I II II II II I / II I , I,,Vl..-.-Q) '"0'oLN-I~01ef-'egl,-10 '';:::1-5,I:;:,-+-11'-~I'j ~ Cl.I(fJICl. III ..... \ \ \ \ \ \ \ \/-"}I\ (alAngle (b) Figure 5.1Lobe-switching antenna patterns anderrorsignal(onedimen­ sion).(a)Polarrepresentation of switched antenna patterns; (b)rect­ angularrepresentation; (c)errorsignal.~IN eIe o\0 (cITime-t Q) II..- (~I-0II'iiiI ::> -+- 0I<P c.IICl. 
 48. S. T. 
 6X. i1uynen. J. 
 152. W. N. 
 Some of the  losses may be incorporated into the other variables in the radar range equation. Care  must be taken to account for all of the system losses while avoiding redundancies.  ch04.indd   39 12/20/07   4:53:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 ARTECH HOUSE: Norwood, MA, USA, 2004; ISBN 978-1-580-53058-3. 22. Pieraccini, M.; Miccinesi, L. 
 TERIZATION  WHICH PROVIDES A DESCRIPTION OF THE SEA CLUTTER DATA IN TERMS OF A STATISTICAL MODEL EG  2AYLEIGH  LOGNORMAL  7EIBULL  AND + 
 (3.11 ).  When used in the FM aitimeter, the technique of servo-controlling the frequency excur­ sion is usually applied at all altitudes above a predetermined minimum. Since the frequency  excursion !if is inversely proportional to range, the radar is better operated at very low  altitudes in the more normal inanner with a fixed AJ, and hence a varying beat frequency. 
 The improvement in signal-to-noise ratio with a video  filter bank is not as good as can be obtained with an IF filter bank, but the ability to measure  the magnitude of doppler frequency is still preserved. Because of foldover, a frequency which  lies to one side of the IF carrier appears, after detection, at the same video frequency as one  which lies an equal amount on the other side of the IF. Therefore the sign of the doppler shift is  lost with a video filter bank, and it cannot be directly determined whether the doppler  frequency corresponds lo an approaching or to a receding target. 
 The switching signal toberelayed isdelayed 16~sec (by reflection inan8-~sec delay line) inorder that itbeclear oftheazimuth pulse atthereceiving station.z The three-pulse code, theazimuth pulse, and thebeacon pulse are“mixed” byusing them alltotrigger ablocking oscillator. The video signals tothe second transmitter are switched twice. The upper-beam video and the beacon video are switched cyclically as described above. 
 Sakamoto. II .. and P. 
 BER OF PULSES PER BEAMWIDTH IS SMALL  THE ANGULAR ACCURACY WILL BE POOR &OR INSTANCE   IF PULSES ARE SEPARATED BY  BEAMWIDTH  SQ} IS BOUNDED BY  BEAMWIDTHS  (OWEVER  IMPROVED ACCURACY CAN BE OBTAINED BY USING THE AMPLITUDES OF THE RADAR RETURNS !N ACCURATE ESTIMATE OF THE TARGET ANGLE IS GIVEN BY   }  QQQ Q      $ $A!!N    &)'52%  3INGLE 
 1965.  7 1. Dewey. 
 Such plots can be obtained at a selected earth loca- tion for a specified level of solar activity (SSN), month, and time of day. Simi- larly to the illustration given in Fig. 24.8, if a collection of experimental sound- ings is taken at the geographical location, SSN, and times of day of Fig. 
  TO  D":  THAT ARE DISTRIBUTED IN SPACE FROM SHORT RANGE    KM  TO LONG RANGE    KM   CLOSE TO THE SURFACE  M  TO THE TOP OF THE ATMOSPHERE WHERE WEATHER IS IMPORTANT  KM   AND TYPICALLY OCCUPY A LARGE FRACTION OF THE SEVERAL MILLIONS OF SPATIAL RESOLUTION CELLS OBSERVED BY THE RADAR -OREOVER  IT IS NECESSARY TO MAKE QUANTITATIVE MEASUREMENTS OF THE RECEIVED SIGNAL CHARACTERISTICS IN EACH OF THESE CELLS  OR hWEATHER TARGETS v TO ESTIMATE SUCH PARAMETERS AS PRECIPITATION RATE  PRECIPITATION TYPE  AIR MOTION  TURBULENCE   AND WIND SHEAR  )N ADDITION  BECAUSE  A HIGH PERCENTAGE  OF RADAR RESOLUTION CELLS CONTAIN USEFUL INFORMATION  METEOROLOGICAL RADARS REQUIRE FAST DIGITAL SIGNAL PROCESSORS  EFFECTIVE MEANS FOR SUPPRESSING ARTIFACTS CAUSED BY THE DATA DENSITY  HIGH DATA 
 A. Wood, and D. J. 
 PDF  ' 3TIMSON   )NTRODUCTION TO !IRBORNE 2ADAR   ND %D  -ENDHAM  .* 3CI4ECH 0UBLISHING     PP n  n  n  * #LARKE  h!IRBORNE RADARv 0ARTS      -ICROWAVE *OURNAL  P  AND P   *ANUARY  AND  &EBRUARY   % !RONOFF AND $ +RAMER  h2ECENT DEVELOPMENTS IN AIRBORNE -4) RADARS v (UGHES !IRCRAFT  2EPORT  PRESENTED AT )%%% 7ESCON   $ +RAMER AND ' ,AVAS  h2ADAR 3YSTEM WITH 4ARGET )LLUMINATION BY $IFFERENT 7AVEFORMS v 53  0ATENT     $ -OONEY  h0OST 
 1259–1270, 2000. ch15.indd   43 12/15/07   6:17:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 TED AND RECEIVED SIGNALS 4HE &ARADAY ROTATION  A OF A LINEARLY 
 (ILL "OOK #OMPANY     PP n  * - (OWELL  h,IMITED SCAN ANTENNAS v PRESENTED AT )%%% !0 
 22. Bean, B. R., and R. 
 Loss of mutual coherence through increasing orbit spacing  is known as baseline decorrelation .52 One may show for reasonably level terrain that  the upper bound constraint on the difference ∆q Rad in elevation angle between the two  orbits is ∆q qRad Rad =λtan / 2rR, where rR is slant range resolution, which is inversely  proportional to range bandwidth. ( Alert : In the SAR interferometric literature, it is  customary to use elevation angle, defined as the angle between the radar line of sight  and the Earth radius vector, as seen from the radar.) For typical large time-bandwidth  product signals, the elevation angle constraint implies that correlation of the pair of  return signals is maintained for orbital separations on the order of a kilometer. For  absolute elevation maps to be derived, however, precise knowledge to the level of one  meter is required of the spatial separation between observation tracks. 
 PORTIONAL TO 0 AV !   WHERE 0AV IS THE AVERAGE POWER OF THE TRANSMITTER AND  ! IS THE  AREA OF THE ANTENNA APERTURE ! FUNDAMENTAL MEASURE OF THE RADAR RANGE PERFORMANCE  IS THEREFORE THE  POWER 
 D.C.  45. Warden, M. 
 14.9 Balanced receiver with a floating LO. of this oscillator is not excessive since FM is contributed only in the ratio of the IF frequency to microwave frequency. An alternative approach to the problem of an IF offset is the free-floating local oscillator employed by Harris et al.13 and by O'Hara and Moore.8 This has a sim- ilarity to the method used to introduce the local oscillator in the Marsh and Wiltshire bridge and requires twin IF amplifiers. 
 Brown (Private communication), 1951. 78. C. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.576x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 FIGURE 20.24  The virtual (solid line) and true (dashed line) reflection heights are given  for July, SSN = 50, and a mid-Atlantic coast refraction area: ( a) 1800 UT is a daytime  example, single hop and ( b) 0800 UT is a nighttime example. See text for an explanation of  the table in the lower right of the figure. 
 2 Boeing 737-700 Wedgetail aircraft showing antennas mounted  above the fuselage ch03.indd   3 12/15/07   6:02:43 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 
 3 ,EE  4 , !INSWORTH  AND - 2 'RUNES  h4ERRAIN TOPOGRAPHY MEASUREMENT  USING MULTIPASS SYNTHETIC APERTURE RADAR DATA v  2ADIO 3CIENCE  VOL   NO   -AYn*UNE     PP n  7 " 3COTT  h&LIGHT TO RADAR 
 DINATES CENTERED AT THE RADAR  THEN MULTIPLICATION BY  ( TRANSFORMS #ARTESIAN COORDINATES   X  Y  Z  INTO POLAR MEASUREMENT COORDINATES RANGE  AZIMUTH  ELEVATION  DOPPLER  AND  (X RY RZ R Y XYX XY XZ RXYYZ R 
 (After Greene and Lebenbaum,50 Microwave J.)  attenuated in passing through the atmosphere. The noise power available over a bandwidth 811  from the imaginary blackbody is kTa B,. .. 
 The radar cross section of a simple sphere is shown in Fig. 2.9 as a function of  its circumference measured in wavelengths (2na/,l, where a is the radius of the sphere and ,l is  the wavelength).11-19•34 The region where the size of the sphere is small compared with the  wavelength (2rra/,l ~ I) is called the Rayleigh region, after Lord Rayleigh who, in the early  1870s, first studied scattering by small particles. Lord Rayleigh was interested in the scattering  of light by microscopic particles, rather than in radar. 
 &REQUENCY !MPLITUDE .OISE  4HE LOW 
 The combination of the I and Q  channels thus results in a uniform signal with no loss. The phase of the pulse train relative to  that of the doppler signal in Fig. 4.226 arid c is a special case to illustrate the effect. 
 scans of data to control K in order to maintain a desired Pfa either on a scan or a sector basis. This demonstrates a general rule: to maintain a low Pfa in various en- vironments, adaptive thresholding should be placed in front of the integrator. If the noise power varies from pulse to pulse (as it would in jamming when frequency agility is employed), one must CFAR each pulse and then integrate. 
 The overlapped areas are then removed. 2.5.3. Third Stage: OF Assisted Object Extraction This stage has two main parts: extraction and elimination. 
 Range compressed sampling process of stepped frequency signal. Figure 15. Target model of ﬁve metal balls. 
 Asa/X (and consequently thegain ofacorner reflector) isincreased, greater attention must bepaid tothe mechanical construction ofthereflector. When the angle between one pair ofplanes differs from 90°, the triply reflected re- turn from the corner splits into two divergent beams, with acon- 1,~ Edge(a)ofcomer incm FIG. 33.-A cluster ofcorner reflectors.FIG. 
 The image signals generated by gain and phase  imbalance are given by Eq. 6.29 and Eq. 6.30. 
 These radars  routinely interleave different surveillance tasks with widely separated carrier frequen - cies—8 and 24 MHz, for example—switching as often as every one or two seconds  while conforming to strict spectral emission standards. Such instantaneous frequency  changes would place unachievable switching demands on the high-level vacuum tube  radio frequency circuits. Meeting power control and amplitude-shaping of waveform  requirements dictates linear operation of amplifiers. 
 GE-21, pp. 118–121, 1983. 144. 
 Similarly, a 2° by 2° beam has 40 dB, a 1° by 10° beam has 36 dB directivity, and so forth. Each beamwidth change is translated into decibels, and the directivity is adjusted ac- cordingly. This relation does not apply to shaped (e.g., cosecant-squared) beams. 
 S. Gilmour, Jr., Microwave Tubes , Norwood, MA: Artech House, 1986, Sec. 12.2. 
 Altliough the apex-matching plate has a broader  bandwidth than matching devices inside tlie transmission line, it causes a slight reduction in  the gai~i and increases the niirior-lobe level of the radiation pattern.  Offset feed.' Both the aperture blockilig and the mismatch at the feed are eliminated with the  offset-$eed parabolic antenna shown in Fig. 7.10. 
 3.9 SPACE-TIME ADAPTIVE   MOTION COMPENSATION Introduction.  Several methods have been described to compensate for antenna  motion. All these techniques are applied in the radar design phase for a specific set of  operational parameters. 
 758-765, 1983. 36. Lhermitte, R.: A 94-GHz Doppler Radar for Cloud Observations, /. 
 Itwasderivedfroma bodyofdatathatextended from)O~ to20-knot windspeeds.(Theuncertainty ofthedata oughttohavebeenindicated illtlli&figure bymakingtheverticalthickness ofeachcurveat least±3dBwide.Th~swasnotdonesoastoavoidtheconfusion thatwouldbecausedbythe wideoverlapofthecurv~s.) .. Theseastateisameasure o(thewaveheight,asshowninTable13.1.Although thesea stateiscommonly usedtodescribe radarsea-clutter measurements, itisnotacomplete measure initselfsince,as'mentioned above,theradarseaechodepends onmanyotherfactors. Seaclutterisalsosometimes described bythewindspeed,butlikewise itisnotasuitable measure byitself.Unfortunately, thereporting ofradarseaechomeasurements isseldom accompanied byacomplete description oftheseaandwindconditions. 
 When the radar receiver employs stretch processing (defined later in this sec - tion), the RF processing bandwidth is significantly larger than the IF bandwidth.  Consequently, the term instantaneous bandwidth  can be confusing. Confusion can be  avoided by using the terms RF waveform bandwidth , LO linear FM (chirp) bandwidth ,  and IF processing bandwidth . 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 With a nonuniform aperture distribution and with losses present, the gain is reduced  by the efficiency term h  to  GA max=42πλη (13.13) If the aperture is considered as a matched receiver, then the amount of energy arriv - ing from a direction q0 is proportional to its projected area. 
 Qlturt. J. Roy. 
 The conducting surfaces are spaced }in.apart and increase in width from about 2ftatthe edge AAtoabout 11ftatthe edge BB. This horn extends over alength ofabout 12ftand isfolded three times. The feeding edge AAoftheparallel plates consists ofaboundary which forms a90° arc, 14* in.inradius. 
 -o'J  From Parseval's theorem. ro J IS(J)l2 df  -00  No  2  1'" ISU)l2 df= r"'' s2(t) dt = signal energy= E  ••. <'Y'l .. 
 Thenoisethatenterstheradarviatheantenna sidelobes canbereduced bycoherent sidclohe cancelers. Thisconsists ofoneormoreomnidirectional antennas andcancelation circuitry usedinconjunction withthesignalfromthemainradarantenna. Jamming noisein theomnidircctionalantennas ismadetocancelthejamming noiseentering thesidelobes ofthe mainantenna.52Anantenna canalsobedesigned tohaveverylowsidelobe levelstoreduce theefTectofsidclobe jamming. 
 Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 102        Figure 11.9  RCS | σ| of a gold -plated metal sphere ( ∅=3.6cm) in the time domain (measured  frequency ranges is 3 -17 GHz).   11.5.2  Circular Disks   Through the integration over the circular area (according to Figure 11.10) results the calcula- tion of the Radar backscattering cross -section of a circular disk with r >> λ , just as in antenna  technology for homogenous arrangement.     Figure 11.10  Geometry for calculating the Radar backscattering cross -section (Aufpunkt =  emission point). 
 U I ! ~· lf-----~y-------~,,/----- (l) Time -(cl Figure 3.10 Frequency-time relation­ ships in FM-CW radar. Solid curve  represents transmitted signal; dashed  curve represents echo. (a) Linear fre­ quency modulation; (b) trianguJar fre­ quency modulation; (c) beat note of  (b). 
 TRACKING FILTER BY SELECTING THE GAIN THAT MINI 
 12.9  Small-Perturbation and Tw o-Scale Model s  .........  12.10  Other Models  .....................................................  12.12 . 
 Sensors 2018 ,18, 1624. [ CrossRef ][PubMed ] 18. Choi, G.G.; Park, S.H.; Kim, H.T.; Kim, K.T. 
 Thisisespecially notedwithend-fire elements (suchaspolyrods orlog­ periodic antennas) whicharespacedcloseenoughtocoupleordiffractenergy.Theeffectof mutualcoupling ontheinputimpedance withsuchelements isusuallysmall.However, the disturbance totheaperture illumination canbequitelargeandcanresultinsignificant differences fromthepatterncomputed byignoring sucheffects. 8.6FEEDS FORARRAYS20.81-84 Ifasingletransmitter andreceiver areutilizedinaphasedarray,theremustbesomeformof network toconnect thesingleportofthetransmitter and/orthesingleportofthereceiver to eachoftheantenna elements. Thepowerdividerusedtoconnect thearrayelements tothe singleportiscalledanarrayfeed.Severalexamples ofsuchnetworks forlineararrayswhere showninFigs.8.2and8.4.Foraplanararraytheproblem ismorecomplicated. 
 C. J. Jakowatz, Jr., D. 
 51−83, January 1978. 33. D. 
 . Radar Systems Engineering  Chapter 5 – Resolution and Accuracy  26     With typical specifications of the threshold value for the cross -correlation, the range resolution  ΔR can be approximately ca lculated as illustrated in Figure 5.4   € ΔR=c0⋅τ/2 (5.16)    Figure 5.4  Range resolution of two targets.     Figure 5.5  Example for the ability to resolve objects at differing ranges & separation distances. 
 These methods either use different sets of feed elements for the sum  and difference beams or apply different array amplitude/phase weightings for each of  the beams. If horn feed elements are used, one approach is to oversize the feeds to  enable multimode excitation for the sum beam as described by Hannan.40 A comparison  of some common monopulse feed configurations is included in Table 12.2. FEED1 FEED2 FEED3 FEED4 0      180 0       180 SUM DELTA AZDELTA EL FEED 1FEED 2 FEED 3FEED 4FEED 1 FEED 3SUM DELTA EL DELTA AZ FEED 3FEED 1FEED 2 FEED 4 FEED 4FEED 2 Feed Excitations for 3 Beam Modes (Sum, Delta El  and Delta Az). 
 SIDED BANDWIDTH 2EAL SIGNALS HAVE SPECTRAL COMPONENTS IN CONJUGATE PAIRS BECAUSE BY USING COM 
 HORN FEED (OWEVER  AS DESCRIBED IN THE DISCUSSION ON FEEDS  THE  
 Occasionally apotentiometer orasine-wave generator isused asthe data-transmitting element. A similar type ofdata transmission isrequired ofservo-controlled scanners: avoltage from thetransmitting element iscompared with avoltage from the knob, etc., that istocontrol the antenna, and the antenna isauto- matically driven inthe direction which will bring the error signal or difference voltage tozero. 9.12. 
 2.Error indicators. (Such displays arenotalways intensity- modulated. ) 111. 
 WATER CONTENT GRAMS PER CUBIC METER  /BSERVATIONS   INDICATE THAT THE LIQUID 
 Relative to the average doppler of the aircraft,  the scattering surfaces located away from the aircraft center will have a small increasing  and decreasing relative doppler frequency as the aircraft yaws right and left. This causes  a spectral spread of the doppler of the echo from the rigid body of the aircraft and   is accompanied by spectral lines caused by moving parts on the aircraft. Components of the target echo from rotating or moving parts of the target cause  doppler lines at frequencies displaced from the airframe doppler spectrum. 
 The ability of the FM-CW radar to measure range provides an addi-  tional basis for obtaining isolation. Echoes from short-range targets-including the leakage  signal-may be attenuated relative to the desired target echo from longer ranges by properly  processing the difference-frequency signal obtained by heterodyning the transmitted and  received signals. a If theCW carrier is frequency-modulated by a sine wave, the difference frequency obtained -3  by heterodyning the returned signal with a portion of the transmitter signal may be expanded  in a trigonometric series whose terms are the harmonics of the modulating frequency 1. 
  OR FIVE 
  -CS  ATMOSPHERIC RADIO NOISE DATA v .AT "UR 3TAND .OTE   !UGUST     $ " 3AILORS  h$ISCREPANCY IN THE )NTERNATIONAL 2ADIO #ONSULTATIVE #OMMITTEE 2EPORT  
 TORS MAY STILL BE FOUND IN OLDER RADARS  THEY PROBABLY WOULD NOT BE IMPLEMENTED IN NEW RADARS AND WILL NOT BE DISCUSSED IN THIS EDITION 4HOUGH ALL THE DETECTORS ARE SHOWN IN &IGURE  AS BEING CONSTRUCTED WITH SHIFT REGISTERS  THEY WOULD NORMALLY BE IMPLEMENTED WITH RANDOM 
 PULSE 3.2 AND A FALSE ALARM PROBABILITY OF  n 4HE !. &03 
 Meteorol. Soc., vol. 56, pp. 
 CHIRP  4HE AMPLITUDE MODULATION IS  AT    ! RECT T4   AND THE PHASE MODULATION IS A  QUADRATIC FUNCTION OF TIME  E T    O@ T    4HE FREQUENCY MODULATION  DEFINED AS THE INSTANTANEOUS FREQUENCY DEVIATION FROM  THE CARRIER FREQUENCY F  IS EXPRESSED IN TERMS OF THE PHASE MODULATION BY   FTD DTI   PF    4HE FREQUENCY MODULATION FOR AN ,&- WAVEFORM IS LINEAR WITH SLOPE EQUAL TO @   FT T "4T T 4I    \\    o aA    . n°{  2!$!2 (!.$"//+  WHERE THE PLUS SIGN APPLIES FOR A POSITIVE ,&- SLOPE AND THE MINUS SIGN FOR A NEGATIVE  SLOPE 4HE COMPLEX ENVELOPE OF THE ,&- WAVEFORM IS EXPRESSED IN TERMS OF THE AMPLITUDE AND PHASE MODULATION FUNCTIONS AS   UT    ! RECTT4  E JO @ T  &IGURE  SHOWS AN EXAMPLE OF AN ,&- BANDPASS SIGNAL WITH A PULSEWIDTH  4    §S   SWEPT BANDWIDTH  "    -(Z AND TIME 
 In the air, for  instance, civil aviation is very largely concerned with the  problem of economic pay-loads, which are not factors of  great importance in war. In hostilities there is almost no  ceiling to the maximum cost of delivering a bomb-load to  an enemy objective. In war, moreover, it may be expedient  to sacrifice bomb-loads in order that more adequate radar  apparatus can be carried. 
 LOOKING AIRBORNE RADAR v  3CIENTIFIC  !MERICAN  VOL   PP n     2 , *ORDAN  h4HE 3EASAT 
 F. H.. N. 
 R.: Reactor Technology, January-March 1980, Los Alamos Scientific Lab- oratory, Prog. Rept. LA-8403-P/?-£/C-80, June 1980. 
 pp. 340-355, April, 1949.  7. 
 SCANNING  PHASED ARRAY RADARS HAVE ALSO BEEN STUDIED EXTENSIVELY IN %UROPE !N ALTERNATIVE APPROACH IS TO EMPLOY DIGITAL BEAMFORMING OR FREQUENCY 
 51  8.4 Coherent Pulse Radar ...................................................................................................... 52  8.5 MTI Radar (Moving Target Indication) .......................................................................... 54  8.5.1 MTI with Delay- Line Canc eller................................................................................ 
 ARRAY RADAR 'OOD %##- PERFORMANCE IS ACHIEVED BY RADIATING AS LARGE AN AVER AGE TRANSMITTER  POWER AT THE HIGHEST TRANSMITTER FREQUENCY PRACTICABLE  COUPLED WITH AS LOW A SIDELOBE LEVEL AS ACHIEVABLE )NCREASING THE TRANSMITTER FREQUENCY  FOR A FIXED ANTENNA SIZE  INCREASES THE ANTENNA GAIN  ' T  WHICH  IN TURN  INCREASES THE RECEIVED TARGET POWER AS  'T &OR MAIN 
 SIVELY WIDE BANDWIDTH CAN PENALIZE DYNAMIC RANGE IF THE INTERFERENCE IS WIDEBAND NOISE %VEN MORE LIKELY IS AN OUT 
 BAND BACKGROUND NOISE LEVEL )N A  
 COMLINKSINDEXPHP   # .AKOS  3 "AKER  * * $OUGLASS  AND ! 2 3ARTI  h(IGH SPEED DATA LINK v !USTRALIA 0ATENT 0#4 !5  7/   $34/ 4ACTICAL 3URVEILLANCE 3YSTEMS $IVISION  3ALISBURY  !USTRALIA  .OVEMBER   $ ! &ULGHUM  h3EE IT  JAM IT  KILL ITv  !VIATION 7EEK  3PACE 4ECHNOLOGY  PP       -AY   . x°{È  2!$!2 (!.$"//+    $ # 3CHLEHER   )NTRODUCTION TO %LECTRONIC 7ARFARE  $EDHAM  -! !RTECH (OUSE    PP n   n  #ASE  *R ET AL  h2ADAR FOR !UTOMATIC 4ERRAIN !VOIDANCE v 53 0ATENT       ( , 7ARUSZEWSKI  *R  h!PPARATUS AND -ETHOD FOR AN !IRCRAFT .AVIGATION 3YSTEM (AVING  )MPROVED -ISSION -ANAGEMENT AND 3URVIVABILITY #APABILITIES v 53 0ATENT        "ARNEY ET AL  h!PPARATUS AND -ETHOD FOR !DJUSTING 3ET #LEARANCE !LTITUDE IN A 4ERRAIN &OLLOWING  2ADAR v 53 0ATENT       2 *AWOROWSKI  h/UTLOOKSPECIFICATIONS MILITARY AIRCRAFT v  !VIATION 7EEK AND 3PACE 4ECHNOLOGY    PP n  *ANUARY     & (ARRIS AND $ ,YNCH  h$IGITAL SIGNAL PROCESSING AND DIGITAL FILTERING WITH APPLICATIONS v %VOLVING  4ECHNOLOGY )NSTITUTE 3HORT #OURSE .OTES  n  PP   n  &EBRUARY   2 &ABRIZIO  h! HIGH SPEED DIGITAL PROCESSOR FOR REALTIME 3!2 IMAGING v IN  )'!233   !NN  !RBOR -)  VOL   P   4 #ULLEN AND # &OSS EDS    *ANES ,AND 
 BASED RADARS IN FIXED INSTALLATIONS CAN PROVIDE A  DEGREE OF NATURAL SIGNAL MASKING TO PREVENT  FOR EXAMPLE  DETECTION BY GROUND 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.76  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 frequencies above. 
 1 n a two-dimensional, rectangular planar array, the radiation pattern may sometimes be  written as the product of the radiation patterns in the two planes which contain the principal  axes of the antenna. If the radiation patterns in the two principal planes are G 1(0.,) and G2(0.,.),  the two-dimensional antenna pattern is  (8. 7)  Note that the angles Oe and Oa are not necessarily the elevation and azimuth angles normally  associated with radar.15· 16 The normalized radiation pattern of a uniformly illuminated rec­ tangular array is  G(O O) = sin2 [Nn(d/J) sin Oa] sin2 [Mn(d/J) sin O,.t  e, a N2 sin2 [n(d/..l) sin Ba] M2 sin2 [n(d/...l) sin OJ (8.8)  where N = number of radiating elements in 0,. 
 The denominator is the maximum-likelihood estimate of a,2, the noise power per pulse. It will detect targets even though only a few returned pulses have a high signal-to-noise ratio. Unfortunately, this will also cause the ratio detector to declare false alarms in the presence of narrow-pulse interference. 
 In view of the limited database and the uncertainties in some of the measure- ment conditions, caution must be exercised in modeling this data. An approxi- mate model is the direct application of the constant--/ monostatic clutter model, Eq. (25.20), when either 0, or S5 is held constant. 
 10.15. TABLE 10.7 Paired-Echo and Weighting Transforms Pairs 5 to 7. The duality theorem 5 permits the interchange of time and fre- quency functions in each of the preceding pairs. 
 Large reflections often occur at scan angles just prior to the emer- gence of a grating lobe into real space, but in some instances such reflections may occur at smaller scan angles. The description of the impedance variation given above made no reference to the feed network or the phase shifters and assumed that the only coupling be- tween elements is via the radiating aperture. The coupling coefficients would be measured, and by superposition the phased-voltage contributions from every el- ement in the array (or at least those in the immediate vicinity) would be added vectorially to produce the voltage reflected back toward the generator. 
   NO   PP n  !PRIL   , % 0ELLON  h! DOUBLE .YQUIST DIGITAL PRODUCT DETECTOR FOR QUADRATURE SAMPLING v  )%%% 4RANS  ON 3IGNAL 0ROCESSING  VOL   NO   PP n  ' ! 3HAW AND 3 # 0OHLIG  h)1 BASEBAND DEMODULATION IN THE 2!330 3!2 BENCHMARK v  0ROJECT 2EPORT 2!330 
 Shaping thefrequency respons~ Nonrecursive filtersemployonlyfeedforward loops.Iffeed­ backloopsareused,aswellasfeedfcirwaid'loops, eachdelaylinecanprovideonepoleaswell asonezeroforincreased designflexibility. Thecanonical configuration ofatime-domain filter withfeedback aswellasfeedforWardloopsisillustrated inFig.4.13.Whenfeedback loopsare . tI • Vout Figure4.13Canonical-configuration combfilter.(AfterWhiteandRuvin,2IRENatl.Conv.Record.). 
 WithSlIch closespacing thephasedifference between thesignalsreceived inthetwofeedsisnegligihly small.Anydifference intheamplitudes between thetwoantenna outputs intheamplitude­ comparison system isaresultofdifferences inamplitude andnotphase.Thephase­ comparison monopu)se, ontheotherhand,measures phasedifferences onlyandisnot concerned withamplitude difference. Therefore theantenna beamsarenotoffset,butare directed toillumin~te acommon volume inspace.Separate antennas areneededsinceitis. difficult to illuniinate a single reflector with more than one feed and produce independeilt  antenna patterns which illuminate the same volume in space. 
 C. Kelley, and D. L. 
 POINT CALCULATION  ONE CONCLUDES THAT ABOUT  D" OF IMPROVEMENT IS OBTAINED BY MAKING A DECISION AT EVERY PULSE 4HE ANGULAR ERROR OF THE BEAM 
 Nevertheless, the concept is widely used and is applicable as long  as the illuminated area is large enough to contain many such centers. Figure 16.1 illustrates the geometry associated with Eq. 16.1. 
 The IF sum-signal output is detected and provides the video input to the range tracker.  The range tracker measures and tracks the time of arrival of the desired target echo  and provides gate pulses that turn on the radar receiver channels only during the brief  period when the desired echo is expected. The gated video is used to generate the dc  FIGURE 9.2  Microwave-comparator circuitry used with a four-horn  monopulse feed ch09.indd   4 12/15/07   6:06:58 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 F. Kuryanov, “The Scattering of sound at a rough surface with two types of irregularity,”   Sov. Phys. 
 G. F. Earl, “HF radar receiving system image rejection requirements,” Proc. 
 Although lowerpeak­ sidclobes canbeobtained inthismanner, thefar-outsidelobes aregenerally considerably greaterthanifthesameillumination function wereusedtoestablish anamplitude taperwith anequallyspacedarray. Theunequally spacedarrayhasseenonlylimitedapplication, primarily because its advantages donotusuallyoutweigh itsdisadvantages. Thereduction ingainandtheincreases insidelobes thatareaconsequence ofthinning theelements areusuallynotdesirable inmost radarapplications. 
  
 Thelinestretcher isoftenimple­ mcnted incoaxial line.Amcchanical linestretcher thatgivesmorephaseshiftforagiven amount ofmotion thanaconventional linestretcher isthehelical-line phaseshifterdueto Stark.SU5Thephasevelocity onthehelicaltransmission lineisconsiderably lessthanthe velocity oflight.Forthisreasonagivenmechanical motionproduces morephasechangethan wouldalinestretcher inconventional transmission line.Thusashorterphaseshiftercanbe had.whichisespecially advantageous atVHForUHFfrequencies. Thereduction inlengthis essentially equaltothewind-up factorofthehelix,whichistheratioofthecircumference to thepitch.Wind-up factorsmayrangefrom10to20inpractical designs. Boththecoaxandthehelicalline-stretchers arenotwellsuitedforthehighermicrowave frequencies. 
 Only the  range measured for target A is correct; those for B and C are not.  One method of distin_g.u-ishing multiple-time-around echoes from unambiguous echoes is  to operate with a varying pulse repetition frequency. The echo signal from an unambiguous  range target will appear at the same place on the A-scope on each sweep no matter whether the  prf is modulated or not. 
 Ulander, L.M.H.; Hellsten, H.; Stenstrom, G. Sythetic-aperture radar processing using fast factorized back-projection. IEEE T rans. 
 Figa-Saldana, J. J. W. 
 FREQUENCY (&  IONOSPHERIC COMMUNICATIONS PROPAGATION ANALYSIS AND  PREDICTION v 6/!#!0 1UICK 'UIDE  HTTPWWWVOACAPCOM  h!DVANCED STAND ALONE PREDICTION SYSTEM v )03 2ADIO AND 3PACE 3ERVICES  4HE !USTRALIAN 3PACE  7EATHER !GENCY  HTTPWWWIPSGOVAU0RODUCTS?AND?3ERVICES    02/0,!" 
 ING LAYER WITH ANALOGUE TECHNOLOGY IE  AT THE MICROWAVE ELEMENT STAGE  TO REDUCE THE  SIDELOBE LEVEL EVERYWHERE II  FIXED WEIGHTS AT THE DIGITAL SUB 
 QUALITY IMAGERY )MAGE QUALITY IS  TYPICALLY MEASURED USING SEVERAL  IMAGE 
 Inc.. New York.  1949. 
 Ontheotherhand,awidetracking bandwidth isrequired toaccurately follow, withminimum lag,rapidchanges inthetargettrajectory orinthevehicle carrying theradarantenna. Thatis,awidebandwidth isrequired forfollowing changes inthe targettrajectory andanarrowbandwidth forsensitivity. Acompromise mustgenerally be madehetween thesecontlicting requirements. 
 DELAY CANCELERS CAN BE REARRANGED AS A TRANSVERSAL FILTER  AND THE WEIGHTS FOR EACH PULSE ARE THE BINOMIAL COEFFICIENTS WITH ALTERNATING SIGN    
 These so-called per - manent (or persistent) scatterers53 support differential interferometric measurements  that may span many repeat visits of the radar, leading to remarkable sensitivity to slow- motion phenomena. For example, multiframe DInSAR‡ analysis of RADARSAT-1  data has led to maps of New Orleans subsidence rates,54 which vary from ∼3 mm/y to  more than 15 mm/y, with a sensitivity on the order of 2.5 mm/y. Any approach to phase difference measurement is subject to the fundamental 2 p  ambiguity characteristic of phase estimation algorithms.55,56 In many radar situations,  knowledge of the physical constraints of the situation, coupled with phase unwrapping  algorithms, is sufficient for the purpose. 
 II, TR 3505 [Image 10694226; Science Museum/Science and Society Picture Library].Airborne Maritime Surveillance Radar, Volume 1 6-2. could be selected in ﬂight by a push-button controller. The tuning of the exact frequencies in each range was done on the ground. 
 12.Zadeh,L.A.,and1.R.Ragazzini: Optimum FiltersfortheDetection ofSignalsinNoise,Proc.IRE, vol.40,pp.1223-123 I,October, 1952. t3.Urkowitz. H.:FiltersfortheDetection ofSmallRadarSignalsinClutter,J.Appl.Phys.,vol.24, pp.1024-1031, August, 1953. 
 , Ê  " 
 The usual i-fand video amplifier, thevarious anticlutter circuits, and the.4FC circuits are included. Atight outer box provides general shielding, but the i-f amplifier and local oscillator have inner shields inaddition. One ofthe most noteworthy features ofthis radar isthe built-in test equipment. 
 FREQUENCY PROCESSING   &IGURE  A SHOWS A SIMULATED POINT 
 BASED #LASS " SYSTEM  )MPORTANTLY  #LASS ! AND " SYSTEMS RECEIVE EACH OTHERS TRANSMISSIONS 4HE COMBINATION OF !)3 AND RADAR 
 Some types of angel echoes which are nonpoint targets are attributed 10  atmospheric effects rather than to birds or inst!cts. Early attempts to account for such echoes  assumed specular reflection from gradients in the refractive index (dielectric constant) of the  atmosphere. Theoretical calculations of the necessary gradients required to account for the  observed angel reflections were excessively large compared to what is found in the real atmo­ sphere. 
 NAL LEVEL TO THAT OF LARGEST SPURIOUS SIGNAL CREATED WITHIN THE RECEIVER 3&$2 IS TYPI 
 C., and l E. Evans: Target-Generated Range Errors, Naval Research Laborntory Mi:111orw1- dum Report 2719, January, 1974.  57. 
 Asthe name implies, theradar data aretransmitted from thesource atwhich they arecollected tosome remote point bymeans ofaradiation link. 17.1. The Uses ofRadar Relay .-Control ofaircraft ineither military orcivilian applications requires the review and filtering ofamass of information gathered from many sources, ofwhich radar isonly one. 
 III in a rough sea at 1000 ft altitude, returns could extend out to 11 nmi upwind and 7 nmi downwind. In order to reduce the saturation effects on the PPI display, a sea return discriminator was introduced. This consisted of a high-pass ﬁlter at the input to the video ampli ﬁer, which could be selected by the operator. 
 VERTER CAUSES A LOSS IN SENSITIVITY 3AMPLES OF NOISE ARE TAKEN AT LONG RANGE  OFTEN BEYOND THE INSTRUMENTED RANGE OF THE RADAR OR DURING SOME SCHEDULED PERIOD )F THE RADAR HAS  . 
 ALS TO VULNERABLE TARGETS IS NOT A VERY EFFECTIVE WAY TO ENHANCE THEIR SURVIVABILITY 4HESE MATERIALS ARE HEAVY  DEMAND UNDUE SURFACE CARE AND MAINTENANCE  SUFFER LIMITED BANDWIDTH  AND NOT LEAST  ARE COSTLY ! FAR MORE VIABLE OPTION  TARGET SHAPING  IS USUALLY AVAILABLE IF ONE IS WILLING TO CONSIDER IT AT THE ONSET OF SYSTEM DEVELOPMENT 3HAPING  3HAPING IS THE RESULT OF JUDICIOUSLY ORIENTING TARGET SURFACES AND  EDGES IN A WAY THAT MINIMIZES THEIR CONTRIBUTIONS TO THE TOTAL  RADAR ECHO 4HIS OFTEN  MEANS SELECTING AIRFRAME SHAPES AND NAVAL HULL PROFILES THAT INITIALLY OUTRAGE AIR 
 This isaratherinteresting result,foritseemstoimplythatthevalueoftimedelayobtained witha straightforward method liketheleading-edge technique canbeasaccurate astheoptimum processing technique described above.Itwasassumed intheanalysisofabandwidth-limited pulsethatamatched filterwasemployed. Ifthespectral widthofthe"rectangular" pulseis changed, thematched filtermustbechanged also. Thermstime-delay errorforatrapezoidal-shaped pulseofwidth2T1acrossthetop,fiat portionandwithriseandfalltimesofT2maybeshownfromEqs.(11.16)and(11.17)tobe b'fJ=(Ti+3T1T2)1/2trapezoidal pulse (11.21) R6EINo Whenthetrapezoidal pulseapproaches inshapetherectangular pulse,thatis,whenT,~T2, Eq.(11.21)becomes bTR~(2i/~Jl/2 Thebandwidth Bisapproximately thereciprocal oftherisetimeT2,andifT1~t/2,wheretis thepulsewidth,thermserroris whichisthesameasthatderivedpreviously forthebandwidth-limited rectangular pulse. 
 PULSE PROCESSING 4HE SYMBOLS  "  AND 4 DENOTE THE BANDWIDTH AND THE PULSEWIDTH OF THE WAVEFORM  RESPECTIVELY  )N CASES WHERE AN INSUFFICIENT DOPPLER SHIFT OCCURS  SUCH AS WITH A STATIONARY OR  TANGENTIAL TARGET  RANGE RESOLUTION IS THE CHIEF MEANS FOR SEEING A TARGET IN CLUTTER  &)'52%     #OMPARISON OF AMBIGUITY FUNCTIONS FOR  .    STEPPED LINEAR AND #OSTAS SEQUENCE SHOWING  THE IMPACT OF FREQUENCY ORDER     
 C  0  10-4.___J, __ .......L..~-'-~-'--~'----'-~"'-'-~-'-~...___.  0 2 3 4 5 6 7 8 9 10  Wovelenglh, cm Figure 13.13 One-way attenuation (<lB/  km) in rain at a temperature of  l8°C. (a) Drizzle- 0.25 mm/h; (h) light  rain I mm/h; (c) moderate rain -4  mm/h: (d) heavy rain-16 mm/h; (e)  excessive rain-40 mmlh. 
 A medium-PRF radar has both range and doppler ambigui - ties.14–17 A blend of medium and high PRF, known as high-medium PRF (which will  be discussed later), is characterized as having only a single-ambiguity for the radial  velocities of interest. For this chapter, a pulse doppler radar is characterized as having  a PRF anywhere within the medium to high PRF regime that results in ambiguous  range measurements during a coherent processing interval. A comparison of MTI and pulse doppler radars is shown in Table 4.2. 
 TIONS OR TECHNOLOGICAL INNOVATIONS !N OUTSTANDING EARLY EXAMPLE IS THE 3EASAT SATEL 
 13, no. I, pp. 10-1 1, Jan. 
 25.3 Geometry for common-coverage area Ac. and rT = 130(V^ + V^r) (25.10) where ht = target altitude, km hR = receive antenna altitude, km hT = transmit antenna altitude, km If the receiver establishes synchronization via the direct-path link, then an ad- equate LOS is also required between transmitter and receiver. In this case ht — O and rR + rT ^ L, where L is the baseline range. 
 Generally the top of the  display correspolids to north. This true bearing display eliminates the blurring of a persistent  screeri display caused by the natural random clianges in heading of the vehicle. It also elimirt-  ates the confusion sometimes found in a relative-bearing display caused by the entire display  rotating as the course of the veliicle is altered. 
 1016), orat excessive powers (above 800 kw, Fig. 10.16), instability yislikely tooccur, Below 1700 gauss theefficiency isobviously unsatisfactory. Considering Fig. 
 681–686, June 1974.  95. D. 
 PURPOSE PROCESSORS 4HIS IS DUE TO THE FACT THAT MOST MICROPROCESSORS ONLY HAVE ONE OR VERY FEW PROCESSING ELEMENTS  WHEREAS &0'!S HAVE AN ENORMOUS NUMBER OF PROGRAMMABLE LOGIC ELEMENTS AND MULTIPLIERS &OR EXAMPLE  TO IMPLEMENT A  
 Relatively thinabsorbers, however, canbeobtained withmagnetic materials havingappropriate dielectric properties.99.100.104 14.6BISTATIC RAOAR57.58 Throughout thisbook,ithasbeenassumed thatacommon antenna isusedforbothtransmit­ tingandreceiving. SucharadariscalledmOlJostatic. Abistaticradarisoneinwhichthe transmitting andreceiving antennas areseparated byaconsiderable distance (Fig.14.12).If. 
  
 Phase run-out is the  change of the transmitted pulse phase during the pulse duration with respect to the  phase of the reference oscillator. If the coho locked perfectly to the end of the trans - mitted pulse, a total phase run-out of 0.02 rad during the transmitted pulse would then  place an average limitation of 40 dB on the improvement factor attainable. Pulse-to- pulse frequency change in microwave oscillators is primarily caused by high-voltage  power supply ripple. 
 PORTING A HETEROGENEOUS ARCHITECTURE  WHERE A VARIETY OF DIFFERENT PROCESSING BLADES OR INTERFACE BOARDS CAN BE PLUGGED INTO THE STANDARD BACKPLANE TO CONFIGURE A TOTAL SYSTEM !T THIS WRITING  BACKPLANES ARE MIGRATING FROM PARALLEL ARCHITECTURES  WHERE DATA IS TYPICALLY PASSED AS  
 585–598, September 1976. 84. L. 
 Theconventional receiver maybeconsidered ascomparing the/11(:"111valueofthe"pulses toapredetermined threshold. Trunkhasshownthatthetrimmed-mean detector ~anbebetter thaneitherthemeanorthemediandetectors.26.27Iftherearenpulsesavailable fromwhichto makeadetection decision, thetrimmed-mean detector discards thesmallest andthelargestof theIIpulsesbefore'takingthemean.Although itsperformance maybegood.itisdifficult to implement inpractice because theItpulsesmustberank-ordered tofindthesmallest andthe largest. Although themediandetector issuperior tothemeandetector (conventional receiver), it isinferiortoboththem-out-of-n detector andthelogarithmic receiver whenc1ullercanhe described bythelog-normaI2t!orthe'Weibulll-l- models.Them-Ollt-of-n detector. 
 14. Sensors 2019 ,19, 1701 The improved interpolation uses the tangent of each arc instead of the traditional ky, and corrects the distorted spectrum. Therefore, the method can effectively improve the utilization of the spectrum in squint SAR. 
 Thefilmcontains thesuperposition oftheholographic signals fromalltheindividual scatterers illuminated bytheradar.Itissometimes calledthephase I,isloryorsiqllalhistory.Theimagethatr'esultsbyilluminating thefilmisfocusedonatilted planesincethecurvature ofthewavefront isproportional totherange.(Thisissomewhat like anopticalanalogoftheradaritself.)Sinceitisundesirable tooperatewiththeimagefocused. INTRODUCTION TO RADAR SYSTECiS  Figt  (Go  Thi:  SC).~  (wit  Resl  4f A Ire 14.4 (a) Synthetic aperture radar image of San Diego, California obtained with the X-band GEM  odyear Electronic Mapping System) radar. Resolution = 12 rn; aircraft altitude = 40,000 ft (12 km  ; is a mosaic covering approximately 19 by 32 km. 
 66. Schultz, F. V.. 
 36. G. Merrill, D. 
 Mass.,1959. 70.IEEEStandard LetterDesignations forRadar-Frequency Bands.IEEEStd521-1976. Nov.30.1976 71.Skolnik, M.I.:Millimeter andSubmillimeter WaveApplications. 
 AGE POWER WAS  7   7  AND  7 0ENETRATION DEPTHS WERE PREDICTED TO BE  M   M  AND  M  WHICH TURNED OUT TO BE CONSISTENT WITH !,3%S PERFORMANCE -!23)3 4HE %UROPEAN 3PACE !GENCYS  -ARS %XPRESS SPACECRAFT INCLUDES THE  -ARS !DVANCED 2ADAR FOR 3UBSURFACE AND )ONOSPHERIC 3OUNDING INSTRUMENT   THE  FIRST ORBITAL SOUNDER TO FLY SINCE !,3% -!23)3 IS A MULTIFREQUENCY DOWN 
 (ILL    ! ) 3INSKY  h7AVEFORM SELECTION AND PROCESSINGv IN  2ADAR 4ECHNOLOGY   % "ROOKNER ED    "OSTON !RTECH (OUSE    #HAP   # 7 (ELSTROM   3TATISTICAL 4HEORY OF 3IGNAL $ETECTION  ND %D  0ERGAMON 0RESS    ' , 4URIN  h!N INTRODUCTION TO MATCHED FILTERS v  )2%  4RANS  )NFORM  4HEORY   VOL )4 
 27.Trunk. (i.V.:Fmther ResultsontheDetection ofTargets inNon-{iaussian ScaCluller, IEEE ·ruJIls..vol.AES-7.pp.553556,May.1971. n.Schlcher. 
 FIELD OBSERVATION POINT  USUALLY BACK  TOWARD THE RADAR  2O IS THE DISTANCE FROM THE ORIGIN OF THE OBJECT TO THE FAR 
 If the source (feed) is displaced from the focus, the reflected wave is somewhat  distorted and this results in gain loss and beam shape distortion. Figure 12.30 shows  the effect of this distortion on the pattern of a typical center-fed reflector as the feed is  moved off-axis. H plane E plane Sidelobes, dB Feed shape Type of Horn Efficiency Slope Slope Sum Difference Simple four-horn 0.58 1.2 1.2 19 10 Two-horn dual-mode 0.75 1.6 1.2 19 10 Two-horn triple-mode 0.75 1.6 1.2 19 10 Twelve-horn  0.56 1.7 1.6 19 19 Four-horn triple-mode 0.75 1.6 1.6 19 19TABLE 12.2  Monopulse Feedhorn Performance FIGURE 12. 
 small additional loss is  incurred, however, compared to using all the taps to establish the ;hreshold. (For example,  with 32 reference cells, a 10-5 probability of false alarm, and 0.9 probability of detection, the . Video  11111u I l  I Tapped t1Play line  Sum I  I J~ Test  cell  I Greoler I  I of I  I I DETECTION OF RADAR SIGNALS IN NOISE 393  Tapped delay line  Sum I  J I  Threshold CFAR  oulput  Figure I0.11 Cell averaging CF AR. 
 IT-9,pp.43-45,January, 1963. 64.Cantrell. B.H.:Sidelobe Reduction inPolyphase Codes,NavalResearch Laboratory Report8108, Washington, D.C.,Apr.13,1977. 
 For example, itispossible tosupply 2500 volts direct current at5ma, 250volts d~rect current at100ma, and –150 volts direct current at5ma, atapproximately the same total weight as that required for conventional power supplies designed torun from 115-volt 60-cps a-c lines. The vibrator power supply just described weighs from 6to8lb,depending onhow itispackaged and onthedegree offiltering required. The output voltage ofavibrator power supply can beregulated by use ofthe series-tube type ofelectronic regulator, which isapt tobe wasteful ofpower. 
 P. Warden: The Design of a Modern Surwillancc Radar,  Radar-Present and Future, IEE Conf. Pub!. 
 Knop, “On the front to back ratio of a parabolic dish antenna,” IEEE Trans. Antennas  Propag ., vol 24, pp. 109–111, January 1976. 
 Weather clutter and chaff differ from ground clutter in that both the mean  doppler shift and the spread are determined by wind velocity and wind shear, the lat - ter arising from the variation of wind velocity with height. Chaff moves with the local  wind, and there are ways (adaptive MTI and optimum doppler processing†) to make an  MTI null out both moving and stationary unwanted echoes.55,136,146 There are two basic  doppler filtering techniques that are used. The first is the MTI, which employs a PRF  that provides unambiguous range coverage while using a comb doppler filter whose  nulls are tuned to the average radial speed of chaff.3 The second is the pulse doppler,  which can use a high PRF to provide unambiguous doppler coverage in conjunction  with a doppler filter bank, allowing separation of target from the chaff.3 A problem with  chaff might be when there is a significant wind shear in the atmosphere. 
 The echoes therefore appear atradial distances corresponding totheir range. Ifthetarget isonthesymmetry axis ofthescan, itisequally illuminated atall“spin” angles and theecho appears asafull circle. Ifitisfaroff axis itisilluminated only through anarrow spin angle (target B)and the arc onthe display isshort. 
 Precautions must usually betaken toreduce radio interference from vibrator power supplies. Small r-fchokes inthepower input leads, mica r-fbypass condensers oninput and output, and careful shielding and grounding usually provide adequate radio interference suppression for aircraft use. Where extremely low noise level isrequired itmay be necessary toshield the vibrator, transformer, and each d-c ripple filter separately, and use r-fchokes ineach transformer connection. 
 186–192, 1948. 111. D. 
 J. I'.. Jr.. 
 It also has the practical advantage  that the magnitude of the conical-scan modulation is amplified because pulse stretching puts  more of the available energy at the modulation frequency. The pulse repetition frequency must  be sufficiently large compared with the conical-scan frequency for proper boxcar filtering. If . 
 The sides ofthethin stainless steel cover are held byspecial springs atthe edge ofthe chassis. Inorder toobtain stability, itwas necessary toprovide thechassis with two baffles toreduce feedback. These consist ofsmall pieces ofsheet metal fastened tothe chassis and making cent actwiththe.bottomofthecover. 
 Error Indicators.—A cathode-ray tube may beused asaradar indicator inaquite different. way from those sofardescribed; that is,asa meter onwhich todisplay various forms ofintelligence. One common useofanerror indicator istoindicate accuracy ofpointing inconnection with aconical scan. 
 Tlie tracking radar clc.q~rir.t~s a target by performing a lirtiited search in the area of the  tlcqigiiatcd target coo~tiiriatcq.  .l'lie scaliriiiig fati-bean1 scarcli radar cat] also provide tracking information to determine  the plitli of ttie target ;itid predict its fittiire position. Each time the radar beam scans past the  t;~rgct. 
 72, Godlove, T. F., V. L. 
 COORDINATE TRACKING BY  PHASE COMPARISON MONOPULSE !NY PHASE SHIFTS OCCURRING IN THE MIXER AND )& AMPLI 
 The theory is based on two  approximations in the application of Eqs. 14.5 and 14.6, both of which are reasonably  effective in a host of practical cases. The first is the far-field approximation , which  assumes that the distance from the scattering obstacle to the point of observation is  large compared with any dimension of the obstacle itself. 
 ( 11.53 )]. The composite three­ dimensional ambiguity surface is shown in Fig. l l.9c. 
 IEEE Geosci. Remote Sens. Lett. 
 John Wiley and Sons. Inc., New York. 1969. 
 When overloading occurs, the gain ofthe receiver must be ‘ reduced. Aslong asthejamming signal isconstant inamplitude, manual gain control isavery satisfactory means ofaccomplishing thegain reduc- tion. However, ifthe radar antenna isscanning orthe c-w signal is modulated, manual control ismuch too slow tobeeffective. 
 THE 
 Time Characteristic (N = 64 Example)Autocorrelation (dB) (N = 64 Example) Frank21 1π Ni j( ) ( )− − i = 1,2,3,… N j = 1,2,3…. N P1 −− −π MM j[ ( )] 2 1 • [(j −1) M + (i −1)] for ith element in   the jth group P2{(/)[( )/] ( / )( )}π π2 1M M M i j− − − i[ ]M j+ −1 2 for ith element in   the jth group P3π Nn2 n = 0,…. N – 1 P4ππn Nk2 − 0 ≤ n ≤ N TABLE   8. 
 PULSE STAGGERING MAY DEGRADE THE IMPROVEMENT FACTOR ATTAINABLE  AS SHOWN IN &IGURE  AND &IGURE   BUT THIS DEGRADATION MAY NOT BE SIGNIFICANT  OR IT CAN BE ELIMINATED BY THE USE OF TIME 
 For geodetic  signals that are expressed through static sea-surface topographic variations, orbits  are required that generate dense track-to-track spacing. Observation of oceanic and  §  The average sea level in the absence of dynamic perturbations of the surface elevation due to tides and currents. *  In the field of oceanography, mesoscale features have scales of several hundred kilometers, as opposed to the much  larger basin scale (the North Atlantic ocean, for example). 
 86. W. J. 
 Asa result the echoes from the two objects blend into a single pip, and rangecan be measured only to the nearest object. The reason for this blending isillustrated in ﬁgure 1.19. In part A of ﬁgure 1.19, the transmitted pulse is just striking the near target. 
 Furthermore, reflector antenna designs are used in modern radar designs  where moderate scan rates and scan volumes are required or low cost is essential. Many legacy radars employ reflector antennas with single feed elements or a cluster  of feeds (i.e., an array) with a fixed beam RF combiner or divider network. Figure 12.25  shows some typical single-feed reflector configurations utilizing horn, waveguide,   and dipole feeds. 
 InafocusedSAR,aphaseweighting expUcPn)alsomustbeappliedto compensate forthespherical wavefront whenthescenetobeimagedlieswithintheFresnel regionofthesynthesized aperture. Thenthesignalsateachrangeintervalmustbesummed. as expressed bytheoperationLSnJ¥,.expUcPn)'Theprocessing iscomplicated bythefactthat n thenumber ofpulsestobesummed isproportional totherange.Furthermore, thephase correction inafocused SARalsodepends ontherange.Addingtothecomplication of processing isthelargebandwidth andhighinformation contentofsynthetic-aperture radar. 
 CLUTTER RATIO RATHER THAN THE SIGNAL 
 Any use is subject to the Terms of Use as given at the website. The Radar Transmitter.  THE RADAR TRANSMITTER  10.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 The above discussion was mainly about the gyrotron amplifier. The gyrotron has  also been operated as an oscillator to produce very high power, but the oscillator ver - sion has not been as popular as the amplifier for radar applications. 
 TABLE 4.4  Discrete Clutter Model Radar Cross Section (m2) Density (per square mile) 1060.01 1050.1 1041 ch04.indd   19 12/20/07   4:52:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 Billingsley9 used the parameters g, vc, and b , respectively, for the gaussian, the  polynomial, and the exponential spectrum models. In addition, the exponent n is needed  for the polynomial model. 
 The reflected wave  from the earth’s surface is received back and ‘com-  pared’ electrically with the waves then being sent out.  The longer the time interval between the emission of  the original wave and its reflection back to the aircraft  —that is, the higher the aircraft is flying—the more will  its frequency differ from that of the wave being emitted  at the instant it is echoed back. Thus the altimeter  receiver is simultaneously fed with two streams of waves,  one from the transmitter and one reflected back from  the ground. 
 VAPOR DENSITIES ARE HIGHEST 4HIS MEANS THAT AT THESE HIGHER FREQUENCIES THE CLUTTER SIGNAL WILL BE STRONGLY AFFECTED BY ATMOSPHERIC ABSORPTION EFFECTS  AND CONSE 
 6, pp. 208–234, 2006. 79. 
 In a multistage chain of linear-beam tubes, the performance of each tube depends in part on the performance of the tubes preceding it. In par- ticular, power flatness (constant power output across the frequency band) re- quires careful specification of flatness for each stage in the presence of a suitable allowance of nonflatness of the stage preceding it. For example, the saturated gain of a tube may be constant across the band, and yet the power output may vary considerably across the band with constant RF drive. 
 The frequency translator is not  rieeded in an airborne doppler navigator since the antenna beam is directed at a depression  angle ather than 90" and a doppler-shifted echo is produced by the motion of the aircraft.  blatched filter detection. The operation of the FM-CW radar described earlier in this section  does not employ optimum signal processing, such as described in Chap. 
  LN  0.      ! COMPARISON OF THE OPTIMAL BEST VALUE OF  -  BINARY INTEGRATOR WITH VARIOUS OTHER  PROCEDURES IS GIVEN IN &IGURES  AND  FOR 0$    AND   RESPECTIVELY 4HE BINARY INTEGRATOR IS USED IN MANY RADARS BECAUSE   IT IS EASILY IMPLEMENTED    IT IGNORES INTERFERENCE SPIKES THAT CAUSE TROUBLE WITH INTEGRATORS THAT DIRECTLY USE  SIGNAL AMPLITUDE AND   IT WORKS EXTREMELY WELL WHEN THE NOISE HAS A NON 
 Ifthevehicle rolls orpitches tosuch anextent that itssearch radar no longer scans the desired part ofthe field ofview, beam stabilization is necessary. This will prevent targets from fading from the indicator; if they arethen indicated, but atafalse position, data stabilization becomes aconcurrent need. Ifthe vehicle momentarily changes heading (yaws) while onacertain course, therelative azimuth oftargets will momentarily aher;theconsequent aberration ofthedisplay can be,and hasbeen, cor- rected by either type ofstabilization. 
 IEEE , vol. 70, March 1982.  9. 
 The false-alarm probability is thus II times as  great. This does not mean that there will be more false alarms, since it is the rate of detection­ decisions that is reduced rather than the average time between alarms. This is another reason  the average false-alarm time Tra is a more significant parameter than the false-alarm probabi­ lity. 
 Res ., vol. 91(C5), pp. 4971–5029, 1987. 
 With change in aspect, the effective reﬂecting area may change, depending uponthe shape of the target. The nearer the angle between the reﬂecting area andthe beam axis is to 90˚, the greater is the strength of the echo returned to theantenna.Shape Targetsofidenticalshapemaygiveechoesofvaryingstrength,depending on aspect. Thus a ﬂat surface at right angles to the radar beam, such as theside of a steel ship or a steep cliff along the shore, will reﬂect very strongechoes. 
 ARRAYS IS A TRADE 
 These transmitterswere of the same type previously ordered from Metropolitan Vickers, which had been diverted for AI radar use. In October 1939 Bowen ’s airborne radar team [ 6] (MAPRE) had moved to RAF St Athan and we re tasked with installing what was to become ASV Mk. I in a Lockheed Hudson aircraft. 
 Section 6summarizes this study. 52. Sensors 2019 ,19, 213 Data at one range cell Block 1 Block 2 Block n Sub-view  image 1Sub-view  image 2Sub-view  image n Position offset Position offset Position offset InvarianceCorrelation Correlation Correlation Invariant Doppler parameters fd'  fdn'  fdn'      (a)  Data at one range cell Block 1 Block 2 Block n Sub-view image 1 Sub-view image 2 Sub-view image n 1 2m 1 2m 1 2mWindowing  manipulation Spatial variant Doppler parametersSpatial varianceCorrelation   fd'   fd'    fdm'    fdn'    fdn'    fdnm'    fdn'    fdn'    fdnm'               (b)  Figure 2. 
 Bennett, E. A. Guiness, and T. 
 SECTION MEASUREMENTS v 'ENERAL -OTORS #ORPORATION  $ELCO %LECTRON $IV 2EPT  2 
 55. Chuang, C. W., and D. 
 The operator of a GPR system searching for pipes may classify the  interfaces between road layers as clutter, whereas the operator of a system measuring  road layer thickness might consider pipes and cables as sources of clutter. Careful  definition and understanding are critically important in selecting and operating the  best system and processing algorithms. Clutter can completely obscure the buried  target and a proper understanding of its source and impact on the radar is essential. 
 The amount of information that can be displayed is limited by the  spot size, which in a high-performance display is less than 0.1 percent of the screen diameter."  In some high-range-resolution radars, however, the number of resolvable range cells available  from the radar might be greater than the number of resolution cells available on the PPI  screen. The result is a collapsing loss (Sec. 2.12). 
 A.The representation ofahorizontal orvertical plane. 1.Undeformed displays. Because ofthe nature ofthe radar data these areusually inthe form ofpolar plots of range and angle (PPI). 
 Many applications are energized by  radar’s natural ability to operate at night or through cloud, fog, smoke, and haze, and  its inherent sensitivity to changes within the scene at wavelength scales. Radar imag - ery has proven to be valuable for a wide variety of applications, from oceanographic  observations (the theme that motivated Seasat) to measurement of millimeter-scale  displacement (such as the subsidence of urban areas or the swelling of volcanoes prior  to their eruption). Canada’s requirement to maintain near-continuous monitoring of its  northern and coastal ice is met primarily by thousands of frames of RADARSAT data  per year. 
 At 1.1 GHz the signal changed 44 dB between O and 30° for the smoothest field and only 4 dB for the roughest. At 7.25 GHz the smoothest field was rough enough to reduce the variation to 18 dB. For most surfaces cross-polarized scatter is lower than like-polarized, often by about 10 dB. 
 Ellis, J. G.: Digital MTI, A New Tool for the Radar User, Marconi Rev., vol. 36, pp. 
 10.4 Theoretical Basic s of SAR   The mathematical treatment of the SAR characteristics result on the basis of Figure  9.6. Radar System Engineering  Chapter 9 – Synthetic Aperture Radar  80        Figure 10.6  Identifiers for calculating SAR.     The Radar, at the height y=h0 with z=0, x=0, illuminates a point P, whose coordinates are (x0,  0, z0). 
 When amplifier stages are serially cascaded without any means of isolating successive stages, the changing input impedance will appear as a varying load impedance to the previous stage. This may very well send the previous stage into oscillation. Figure 5.8 illustrates splitting-combining configurations that provide the neces- sary isolation by utilizing reflected signal phase cancellation techniques.Parameter Amplitude sensitivity to RF drive Amplitude sensitivity to collector voltage Phase sensitivity to RF drive Phase sensitivity to collector voltage Phase runoutValue 0.2-0.9 dB/dB* 0.2-04 dB/Vt 10-13°/dB 0.5-1. 
 TRAL CONTENT MUST BE APPLIED AT THE OUTPUT OF THE TRANSMITTER 4HE AMPLIFIER #LASS 
 This limitation has sometimes been called  scanning fluctuations or scanning modulation.  The computation of the limitation to the improvement factor can be found in a manner  similar to that of the clutter fluctuations described previously. The clutter attentuation is first  found using Eq. 
 However, when  only a few pulses are available fo'r' processing ~here is probably little that can be done to  control the shape of the filter characteristic. Thus, there is ~ot much to be gained in trying to  shape the nonrecursive filter response for three-or four-pulse cancelers other than to use the  classical sin2 or sin3 response· of the," optimum,, canceler.  The N-pulse nonrecursive delay-line canceler allows the designer N zeros for synthesizing  the frequency response. 
 DUSK ORBIT  IN WHICH THE SATELLITEAND ITS SOLAR 
 -(Z  RADAR TRANSMITTING A #7 PULSE OF DURATION  S    MS AND THE REQUIREMENT THAT NO  SINGLE SYSTEM INSTABILITY WILL LIMIT THE -4) IMPROVEMENT FACTOR ATTAINABLE AT A RANGE OF  NMI TO LESS THAN  D"  A VOLTAGE RATIO OF  4HE RMS PULSE 
 IZATION AND B  VERTICAL POLARIZATION #OURTESY OF ) +ATZ .   '2/5.$ %#(/  £È°ÎÇ &)'52%     "OUNDARIES OF MEASURED RADAR RETURN NEAR VERTICAL INCIDENCE   BASED ON 3ANDIA #ORPORATION DATA  FROM & * *ANZA  2 + -OORE  AND " $  7ARNER  &)'52%     !NGULAR RESPONSE OF THE SCATTERING COEFFICIENT FOR FIVE MOIST FIELDS WITH DIFFERENT ROUGHNESS AT  A   '(Z  B   '(Z  AND C    '(Z AFTER & 4 5LABY  2 + -OORE  AND ! + &UNG  . 
 Borkowski, “A highly uniform and high throughput  double selective PHEMT process using an all wet etch chemistry,” presented at GaAs MaTech  Conference, 2002. 19. C. 
       !      ! 
 The first of these is for  enhancing visual aids to navigation, such as buoys and landmarks, to enable them to  be prominently identified on a radar display. These are normally called racons  (as a  contraction of radar beacons ). Such systems form an important navigational service  that is well liked by mariners. 
     
 MONOSTATIC IS USED TO DENOTE CONFIGURATIONS IN WHICH THE TRANSMIT AND  RECEIVE SITES ARE SEPARATED  AS IS OFTEN DONE WITH RADARS EMPLOYING &- 
 Radar System Engineering  Chapter 12 – Selected Radar Applications  144        Figure 13.12  Coverage of an ACC sensor (Courtesy A.D.C.)     Today the collision region is normally covered by 3 radiated beams, which are sequentially switched.  A further field of vision is required in the near region, e.g. during city driving for  the acquisition and detection of incoming traffic from the sides and perpend icular directions. 
 Basically, there are two approaches to  solving this problem: (1) remove large return from the calculation of the threshold25–27 or  (2) diminish the effects of large returns by either limiting or using log video. The technique  that should be used is a function of the particular radar system and its environment. Rickard and Dillard26 proposed a class of detectors DK, where the K largest samples  are censored (removed) from the reference cells. 
 The shape of the subreflector determines how the power will be distributed across the  primary reflector and thereby provides some control over amplitude in addition to  phase in the aperture, making it possible to produce very low spillover or to produce  a specific low-sidelobe distribution. By suitable choice of shape, the apparent focal  length can be enlarged so that the feed size is practical or even feasible. This is some - times necessary for monopulse operation. 
 WAVE RADARS ARE USEFUL FOR SENSING AND PROBING NEWLY DEVELOPING CLOUDS 2ESEARCHERS OFTEN NEED A WIDE RANGE OF THESE CAPABILITIES SIMULTANEOUSLY &ROM THE RADAR ENGINEERING STAND 
   BUT IT WAS NOT JUST A REPLACEMENT OF THE TRANSMIT 
 OCEANIC SURFACES 4HE ACCURACIES OF WIND SPEED AND DIRECTION OVER n MS WERE  o  MS AND  o  O  RESPECTIVELY 4HE DATA WERE NOT  SUFFICIENT TO AVOID DIRECTIONAL AMBIGUITIES  HOWEVER .OMINAL RESOLUTION WAS  KM  DETERMINED BY THE INTERSECTION OF THE ANTENNA PATTERN AND ISO 
    
 A dynamic range of around  100 dB is typically achieved in perhaps an eight-stage amplifier. Filtering, consis - tent with the transmitted pulse length, is applied within the IF amplifier. The output  from the log amplifier enters a diode-based envelope detector, converting the signal  to baseband for subsequent threshold processing. 
 The thumbtack ambiguity diagram,  Fig. 11.13c, is obtained with noise or pseudonoise waveforms. The width of the spike at the  center can be made narrow along the time axis and along the frequency axis by increasing the  bandwidth and pulse duration, respectively. 
 22.9 the required number of vehicles are shown as well as the number of orbit planes in which they are distributed to pro- vide continuous coverage of the entire earth's surface from circular polar orbits. It is seen that six vehicles in two orbit planes can be used for vehicle altitudes greater than about 6000 nmi. There is no nadir hole in the satellite coverage. 
 20. Rubin, W. L., and S. 
 For radars close to the auroral zone, the options are generally more limited. Ionospheric irregularities that scatter back to the radar receiver occur much more often  at night than by day at any latitude. Sensible siting of the radar, ensuring good front-to- back ratios on the antennas, employing vertical nulling if available, and using adaptive  signal processing techniques (or at least maintaining low receive array sidelobes) are all  effective tools for mitigating auroral, meteor, and other ionospheric clutter. 
 For the determination of direction and for the concentration of the transmittedenergysothatagreaterportionofitisuseful,theantennashouldbe highly directive. The higher the carrier frequency, the shorter thewavelength and hence the smaller is the antenna required for a givensharpness of the pattern of radiated energy. The problem of generating and amplifying reasonable amounts of radio- frequency energy at extremely high frequencies is complicated by thephysical construction of the tubes to be used. 
 RESIDUE (dB)IMPROVEMENT FACTOR (dB) . FIG. 16.20 Optimized DPCA phase compensation. 
 The corresponding threshold T1 is  T1 = s (−2 ln PN)½ (7.10) A comparison of the optimal (best value of M) binary integrator with various other  procedures is given in Figures 7.9 and 7.10 for PD = 0.5 and 0.9, respectively. The binary integrator is used in many radars because (1) it is easily implemented;  (2) it ignores interference spikes that cause trouble with integrators that directly use  signal amplitude; and (3) it works extremely well when the noise has a non-Rayleigh  density.19 For N = 3, comparison of the optimal binary integrator (3 out of 3), another  binary integrator (2 out of 3), and the moving-window detector in log-normal interfer - ence (an example of a non-Rayleigh density, where the log of the return has a gaussian  density) is shown in Figure 7.11. The optimal binary integrator is much better than  the moving-window integrator. 
 Elect. Engs. pub].). 
 FREE BANDWIDTH IN ANY OF THE DESIGNATED REGIONS IS ROUGHLY   OF THE CENTER FREQUENCY OR  ( n , ( 4HUS  RECEIVERS REQUIRING A WIDE BAND 
 84 three-delay canceler, 2.37 two-delay canceler, 2.36 unwanted targets, removal of, 2.96 to 2.100 Moving targets, in SAR, 17.23 to 17.27 Moving Target Detection (MTD), 2.6 to 2.9 block diagram, 2. 6 to 2.7 ducted propagation, effect of, 2.95 Moving-window detector, 7.4 to 7.7 MTBF, of klystrons, 10.6 to 10.7 Multi-beam digital beamforming, 25.17 to 25.19 Multifunction radar, 1.7, 13.1 Multifunctional Fighter Aircraft Radar (MFAR), 5.2 to 5.7 processing, 5.5 range-doppler situation in, 5.7 to 5.8. software structure, 5.6 to 5.7 Multipath, 26.4 to 26.5 in tracking radar, 9.37 to 9.40, 9.46 to 9.47 Multiple-beam klystron, 10.7 to 10.8 Multiple hypothesis algorithm in track association, 7.40 to 7.41 Multiple Object Tracking Radar (MOTR), 9.2, 9.26 Multiple reflector antenna, 12.21 to 12.24 Multiple scattering in target recognition, 14.35 Multiplicative noise, 4.28, 18.18 in SAR, 17. 
 Ó°nä  2!$!2 (!.$"//+  !$ CONVERTERS ARE TYPICALLY CHARACTERIZED BY THEIR SIGNAL 
 RAE Royal Aircraft Establishment RAF Royal Air Force RC resistor –capacitor RCS radar cross-section RDF radio direction F ﬁnding RF radio frequencyRN Royal Navy RRDE Radar Research and Development Establishment RRE Royal Radar EstablishmentRSRE Royal Signals and Radar EstablishmentSAAF South African Air Force S-band 10 cm radar band (3000 Mc/s) SRASV short range ASVSRDE Signals Research and Development Establishment SWG standard wire gauge TR transmitter –receiver TRE Telecommunications Research Establishment UK United Kingdom US United StatesUSA United States of America USN United States Navy VCR valve, cathode rayVHF very high frequencyVLR very long range VR valve, receiver VSWR voltage standing-wave ratioVT valve, transmitter WWII World War Two X-band 3 cm radar band (10 000 Mc/s)Airborne Maritime Surveillance Radar, Volume 1 xvi. IOP Concise Physics Airborne Maritime Surveillance Radar, Volume 1 British ASV radars in WWII 1939–1945 Simon Watts Chapter 1 ASV radar development 1.1 Introduction Today air to surface vessel (ASV) radars, or more generally airborne maritime surveillance radars, are installed on maritime reconnaissance aircraft for long-range detection, tracking and classi ﬁcation of surface ships (ASuW —air to surface warfare) and for hunting submarines (ASW —anti-submarine warfare). Such radars were ﬁrst developed in the UK during WWII, as part of the response to the threat to shipping from German U-boats. 
 TERING CROSS SECTION MAY BE SAID TO BE  ERGODIC  WHICH MEANS THAT THE STATISTICAL RESULTS  OBTAINED BY TIME AVERAGING FROM A SMALL CELL ARE EQUIVALENT TO AN ENSEMBLE AVERAGE FROM A LARGER CELL  PROVIDED THAT THE NUMBER OF hSAMPLESv IS THE SAME IN THE TWO CASES  &OR THIS REASON  THE STATISTICAL IMPLICATIONS OF EXPERIMENTAL  DATA CAN BE PROP 
 RIOUS LEVELS BY ADDING DITHERING TO REDUCE THE EFFECTS OF LIMITED WORD LENGTHS 4HE EFFECT OF THESE TECHNIQUES AND THE SPURIOUS SIGNALS THAT THEY ARE DESIGNED TO MITIGATE SHOULD BE CONSIDERED CAREFULLY AS THEY MAY BE DETRIMENTAL TO RADAR PERFORMANCE 4HE USE OF DITHERING WILL RANDOMIZE THE SPURIOUS SIGNAL  RESULTING IN PULSE 
 IN ALONG A SIDE MEASURED AT  -(Z 4HE ((  AND (6 PATTERNS HAVE BEEN  ARTIFICIALLY LOWERED  D" FOR CLARITY  #OURTESY OF 3 0 7EI ET AL   THE "OEING #OMPANY /RIGINAL DATA COURTESY OF THE "OEING #OMPANY  3EATTLE  7ASHINGTON       %"         
 Athin spacer between thetwo coils isofsuch thickness astomake thecoupling just transitional. The gain perstage isapproxi- mately 11db,and the single-stage bandwidth 25Me/see. The 6AK5 tube ischosen inpreference tothe 6AC7 because itis smaller, takes less power, and hasasmaller variation ininput and output capacity. 
 H.: Sidelobe Reduction in Polyphase Codes, Naval Research Laboratory Report 8108,  Washington, D.C., Apr. 13, 1977.  65. 
 They would, therefore, precede a final power amplifier for transmitting and follow a  preamplifier for receiving. A further method of providing delay is possible by translating the problem from the  microwave domain and delaying at IF. FIGURE 13.29  Time-delay configurations: ( a) time delay by choosing upper or lower paths and ( b) time  delay by using switched circulators ch13.indd   45 12/17/07   2:40:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 EXP EXP       4HE SECOND FACTOR IN THIS EXPRESSION REPRESENTS THE PHASE SHIFT CAUSED BY THE DOPPLER  SHIFT OF THE CLUTTER RETURNS &OR A KNOWN TARGET DOPPLER SHIFT  THE RECEIVED TARGET RETURN CAN BE REPRESENTED BY  AN . 
  
 OF 
 The maximum of the U functional  can be estimated by an exhaustive search in the range of values of interest of ( q, f)  or by using a fast recursive algorithm.114 The recursion can be initialized with the  angular coordinates of the main-beam pointing. By replacing the estimated distur - bance covariance matrix into the U functional, a Constant False Alarm Rate (CFAR)  detector is obtained.115 Thus, the comparison of the U functional with a suitable  threshold permits the target detection maintaining the prescribed CFAR. Only for  the range cell in which the detection occurred, the radar signals are taken and further  processed by the ML algorithm to produce the target DoA estimate. 
 CODE PREDICTION OF THE EDGE 
 METRIC MEASUREMENTS AT BOTH WAVELENGTHS 4HE TECHNICAL CHARACTERISTICS ARE SIMILAR TO THE .EXRAD SPECIFICATIONS 4HE ANTENNA BEAMS ARE MATCHED WITH APPROXIMATELY  n  BEAMWIDTH AND THE LARGE 3 
 12,11. CHAPTER 13 THE RECEIVING SYSTEM—INDICATORS BYL.J.HAWORTH THE CATHODE-RAY TUBE The effectiveness ofacathode-ray tube asaradar indicator isinflu- enced byanumber offactors, among them: (1)thesize ofthetube face; (2)theintensity ofthe emitted light, which isdetermined byboth the strength ofthe electron beam and the efficiency ofthe screen; (3)the decay properties ofthe screen and the manner inwhich itintegrates repeated signals; (4)theresolution; (5)the grid-modulation characteris- tics; (6)theeffect ofthetube ontheover-all complexity, weight, size, and power dksipation ofthecomplete indicating equipment. These properties arenotindependent, and inmany cases acompromise among them must bereached. 
 34. H. R. 
 79, pp. 810–826, June 1991. 84. 
 As shown in the next  section, the creeping wave causes the echoes from small spheres to vary with sphere  size. The mechanism can also be present for other smooth bodies, such as the generic  missile depicted in Figure 14.1. The creeping wave mechanism is never a significant  one for military and civilian targets. 
 RADAR ENGINEER TO RECOGNIZE IS THAT THEY WERE ORIGINALLY SELECTED  TO DESCRIBE THE RADAR BANDS USED IN 7ORLD 7AR )) 3ECRECY WAS IMPORTANT AT THAT TIME SO THE LETTERS SELECTED TO DESIGNATE THE VARIOUS BANDS MADE IT HARD TO GUESS THE FREQUENCIES TO WHICH THEY APPLY 4HOSE WHO WORK AROUND RADAR  HOWEVER  SELDOM HAVE A PROBLEM WITH THE USAGE OF THE RADAR LETTER BANDS /THER LETTER BANDS HAVE BEEN USED FOR DESCRIBING THE ELECTROMAGNETIC SPECTRUM BUT  THEY ARE NOT SUITABLE FOR RADAR AND SHOULD NEVER BE USED FOR RA DAR /NE SUCH DESIGNATION  USES THE LETTERS !  "  #  ETC  ORIGINALLY DEVISED FOR CONDUCTING ELECTRONIC COUNTERMEASURE EXERCISES  4HE )%%% 3TANDARD MENTIONED PREVIOUSLY STATES THAT THESE hARE NOT CONSISTENT  WITH RADAR PRACTICE AND SHALL NOT BE USED TO DESCRIBE RADAR 
 Wiesbeck, "Fundamentals of broad - band polarimetric r a- dar m etrology," in PIERS (Progress in Electromagnetics Research symposium) NSF  Workshop, Boston, Massachusetts, USA, p. 164, July 25- 27, 1989   − W. Wiesbeck, D. 
 42 
 Ifthe receiver gain control issethigh, most ground signals rise tosaturation and ground return takes onthe more flattened texture seen inFig. 317. 3.14. 
 11.6. The amplitude distribution across the aperture as a . 410 INTRODUCTION TO RADAR SYSTEMS  y  Figure 11.6 Rectangular rccc1vmg  aperture of width D and amplitude  distribution A (x) giving rise to radiated  pattern G,,(O). 
 AP-5.  pp. 21 1--216. 
 The relatively fat cathode, required for theoretical reasons, can dissipate more heat  than can a thin cathode.  In the interaction space (5) the electrons interact with the d-c electric field and the  magnetic field in such a manner that the electrons give up their energy to the RF field. The  magnetic field, which is perpendicular to the plane of the figure, passes through the interaction  space parallel to the cathode and perpendicular to the d-c electric field. 
 , 
 The  tracking circuits also eliminate false hit-reports which do not form logical tracks. The output  of the automatic tracker is what is displayed on the scope. Since the MTD processor eliminates  a large anloi~nt of tlie clutter and lias a low false-detection rate, its output can be reliably  rcnlotcd via narrow baridwidtl~ tclcplione circuits. 
 The shape ofthis area and thebrightness of particular sections remain sensitive toaltitude and direction ofapproach, but the whole group ofsignals isstrong enough togive areliable indica- tion under most circumstances. The appearance ofcity signals ofvarious sizes isillustrated inFig. 3.28, aphotograph obtained over theKanto plain north ofTokyo. 
 More commonly, MTI and pulse doppler radars are pseudo-coherent, as illus- trated in Fig. 3.10. The coho is the master reference for the phase detector and may be the clock from which the interpulse periods are determined. 
 This property, together with the large, flat, parallax- free image, makes the display extremely useful for measurement and plotting. However, ithas serious inadequacies which arise from short- comings ofthe skiatron tube. Contrast isalways low, particularly at low duty ratios. 
  
 The sine and cosine of the number are extracted  from the contents of a read-only memory and convert­ ed to a pair of analog signals that are then applied to  a single sideband modulator to impart a parabolic phase  (linear frequency) modulation on a carrier signal. A sub- 178 Dual  AID  converters  Waveform  samples Transmitter  (TWTA)  AGe  Transmit  trigger  Major characteristics :  Antenna bandwidth: 2 deg  Frequency : 13.5 GHz  Peak transmit power: 20 W  Average transmit power: 2 W Digital  chirp  generator  Receive  trigger  Pulse width (uncompressed): 102.4 J.l.S  Pulse width (compressed): 3.125 ns  Pulse repetition rate: 1020 Hz  Figure 4-Block diagram of the GEOSAT radar.  sequent multiplication by 8 then results in the desired  320-megahertz bandwidth pulse. 
 The de- lay line is an exception. When one attempts to servo-out phase noises at the FIG. 14.8 FM noise in microwave sources. 
 ** Average of TSL power ratioTABLE   8. 3 Comparison of Linear FM and Nonlinear FM Waveform Performance* ch08.indd   16 12/20/07   12:50:09 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 GE-21, pp. 62–71, 1983. 72. 
 DELAY CHANGES THE CORRELATION BETWEEN THE PHASE OF THE SPURIOUS MODULATING FREQUENCY FROM THE TRANSMIT PATH WITH THE PHASE FROM THE RECEIVE PATH  4HIS CAN RELIEVE THE COMMON DISCRETE LEVEL REQUIREMENT FOR  LOW 
 The processing.time T, is  included to emphasize that an OTH radar is usually a doppler-processing radar that requires a  dwell tinie of T, seconds if a frequency resolution of 1/T, hertz is to be achieved.  Tlie radar cross sectiorl (T of targets at HF is often different than at microwaves. Sir~ce  nlariy targets have dimensions comparable to the HF wavelength, or component structures  witti dimensions comparable to the wavelength, the target is often in the resonance region  where the radar cross sections are gerlerally larger than at microwaves. 
 Targets thatareseenatlongrangeandata particular heightwithacosecant-squared antenna, willbemissedatshorterrangeswhenSTC i~used.Toincorporate bothbeamshaping andSTC,thepattern musthavehighergainat higher-elevation anglesthanwouldacosecant-squared pattern. Figure7.27aillustrates the antenna elevation patternforanair-search radarwhichisdesiredtocompensate forSTCand yetprovideasignalindependent ofrange,asdoesthecosecant-squared pattern.97 Figure7.27b showsthecoverage ofalong-range radarwithsuchanantenna pattern. Beamshaping mayalsobeemployed toincrease thetarget-to-clutter ratioinsomecases. 
 6.44  Types of Radomes and General  Considerations  ................................................  6.44  Environmental Effects  ........................................  6.45 Airborne and Missile Radomes  .......................... 
 39. Andreasen, M. G.: Scattering from Bodies of Revolution, IEEE Trans., vol. 
   PP n  .OVEMBER   $ + "ARTON   &REQUENCY !GILITY AND $IVERSITY  IN 6OL  OF  2ADARS  .ORWOOD  -! !RTECH  (OUSE  . £ä°£/ iÊ,>`>ÀÊ/À>ÃÌÌiÀ / >ÃÊ°Ê7iÊ>`Ê iÀÀÊ- £ä°£Ê  /," 1 /"  2OLE OF THE 4RANSMITTER IN 2ADAR  )F A RADAR SYSTEMS DESIGNER COULD ASK FOR  ANYTHING HE OR SHE WANTED IN A RADAR TRANSMITTER  THAT WISH MIGHT BE SOMETHING LIKE  THE FOLLOWING 0ROVIDE THE NECESSARY TRANSMITTED ENERGY WITH THE NEEDED AVERAGE AND PEAK POWER  AS WELL AS THE REQUIRED STABILITY AND LOW NOISE FOR GOOD DOPPLER PROCESS 
 It is important to appreciate the effect of the material in close proximity to the  antenna. In general this material, which in most cases will be soil or rocks or indeed  ice, can be regarded as a lossy dielectric and by its consequent loading effect can play  a significant role in determining the low frequency performance of the antenna and  hence GPR. The behavior of the antenna is intimately linked with the material and,  in the case of borehole radars, the antenna actually radiates within a lossy dielectric,  whereas in the case of the GPR working above the surface, the antenna will radiate  from air into a very small section of air and then into a lossy half space formed by  the material. 
 7.8.—Video mapping transmitter. The aperture infront ofthephototube is small enough sothattheparallax between the spotontheCRT screen andthemarks onthe plotting surface issmall. orthree feet from themap receives asignal whenever the rays from the spot tothe photocell undergo achange inabsorption. 
 IZATION AND RECEIVE THE ORTHOGONAL OR BOTH POLARIZATIONS  EITHER CROSSED DIPOLES OR  CIRCULAR OR SQUARE RADIATORS SEEM SUITABLE 7ITH APPROPRIATE FEED SYSTEMS  BOTH ARE CAPABLE OF PROVIDING VERTICAL AND HORIZONTAL POLARIZATION INDEPENDENTLY AND MAY BE COMBINED TO PROVIDE ANY DESIRED POLARIZATION  INCLUDING CIRCULAR 3UCH POLARIZATION DIVERSITY ADDS CONSIDERABLE COMPLEXITY  REQUIRING TWO FEED SYSTEMS OR SWITCHES AT THE RADIATING ELEMENT LEVEL #IRCULAR 0OLARIZATION  &ROM THE POINT OF VIEW OF THE ANTENNA DESIGNER  CIRCULAR  POLARIZATION IS POSSIBLE  THOUGH DIFFICULTIES MAY BE ENCOUNTERED IN MATCHING FOR LARGE SCAN ANGLES /N SCANNING  A COMPONENT OF THE UNDESIRED ORTHOGONAL POLARIZATION WILL BE GENERATED   AND SOME PROVISION SHOULD BE MADE TO ABSORB THAT ENERGY 7ITH A  CONVENTIONAL CIRCULARLY POLARIZED ANTENNA  SUCH AS A PARABOLIC DISH WITH A CIRCULARLY POLARIZED FEED  GOOD CIRCULARITY MAY BE OBTAINED OVER PART OF THE MAIN BEAM  WITH RAPID DETERIORATION OVER THE REST OF THE PATTERN 7ITH A PLANAR ARRAY  THE RELEVANT BEAM 
 FLYING PENETRATING TAR 
 HORIZON DETECTION  &IGURE  SHOWS HOW THE  SURFACE WAVE DECAYS WITH RANGE  PARAMETRIC IN FREQUENCY FOR THE CASE IN WHICH BOTH THE RADAR ANTENNA AND THE TARGET ARE NEAR THE SEA SURFACE 4HESE CURVES ARE FOR A SMOOTH SURFACE AND USE A  EARTH RADIUS TO APPROXIMATE ATMOSPHERIC REFRACTION EFFECTS 4HE PROPAGATION CODE USED HERE IS DUE TO "ERRY AND #HRISMAN   AND IT IS QUITE FLEXIBLE   PERMITTING ANTENNA AND TARGET ALTITUDES  SURFACE CONDUCTIVITY AND PERMITTIVITY  POLARIZA 
 TION INTERVAL  AND  2MAX   DISTANCE FROM THE RADAR TO THE SCENE CENTER AT THE BEGINNING  AND END OF THE DATA COLLECTION INTERVAL 4HEN   $$22 26T 2, 222! 
 CALLED CUTOFF VELOCITY   ITS TRANSIENT RESPONSE  AND THE LOSS IN SENSITIVITY CAUSED BY THE CLUTTER MAP SIMILAR TO A #&!2 LOSS  4HE MINIMUM CELL SIZE WILL BE CONSTRAINED BY THE SIZE OF THE RADAR RESOLUTION CELL &)'52%  #LUTTER MAP CELL DEFINITION .   -4) 2!$!2  Ó°nx %ACH MAP CELL IS UPDATED BY THE RADAR RETURNS OR RESIDUES  FALLING WITHIN ITS BORDERS  OR IN ITS VICINITY  ON SEVERAL PREVIOUS SCANS 4O SAVE MEMORY  THE CELLS ARE USUALLY  UPDATED BY USING A SIMPLE RECURSIVE SINGLE 
 Figure 5.la is a polar rep-  resen~atiorl of the antenna beam (minus the sidelobes) in the two switched positions. A plot in  rectarigular coordinates is shown in Fig. 5.lh, and the error signal obtained from a target not  on the switching axis (reference direction) is shown in Fig. 
 8.9, has been frequently used in high-power digital phase shifters. It  consists of a thin slice of high-resistivity intrinsic semiconductor material sandwiched between  heavily doped low-resistivity P+ and N+ regions. The intrinsic region acts as a slightly lossy  dielectric at microwave frequencies and the heavily doped regions are good conductors. 
 The last category is other algorithms, such as spare representation (SR) method [ 25]. A sparse metric is deﬁned to iteratively estimate the sparse scatterer coefﬁcients and phase errors, while the SR method is proposed to only deal with autofocus issues and cannot simultaneously obtain high-resolution images. The scatter-based algorithms are based on the processing of dominant scatter center and pay attention to the phase history of isolated scatter center. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar.  TRACKING RADAR  9.436x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 RF frequency, detuning, and temperature. 
 179- 186.  April, iir62.  HX. 
 follow. The final stage consists ofapair of4E27 tubes operated asa Class Camplifier with anaverage r-foutput power ofabout 100watts. The equipment isdesigned toaccommodate amaximum video bandwidth of2Me/see. 
 The  optimum season for duct formation in the tradewind region between Brazil and Ascension  Islands occurs in November. 2 9 ft has been said, however, that elevated ducts giving rise to  strong persistent anomalous propagation occur throughout most of the year over at least  one-third of the oceans.27  To take maximum advantage or propagation in an elevated duct, the radar and target  should be at an altitude near that of the duct. This is found from both theory and measure­ ments made by aircraft Oying at various altitudes. 
 Projected area drops as cosine  of scan (cone) angle. Mutual coupling between radiating elements further reduces the  effective area. Scan loss must be accounted for on transmit and receive. 
 Noise.—It iswell known that despite our ability toamplify afeeble electrical signal bypractically any desired factor, itisstill not possible todiscern anarbitrarily weak signal because ofthe presence of random elect rical fluctuations, or“noise.” Ifthe true signal entering any receiver ismade weaker and weaker, itsubsides eventually into the fluctuating background ofnoise and islost. What istheorigin ofthese fluctuations, and what factors determine precisely the level atwhich theradar signal ishopelessly obscured bythem? Before weattempt toanswer these decisive questions, itisworth while toconsider briefly the limit ofuseful sensitivity ofanordinary low-frequency radio receiver. This limit isalso set byrandom dis- turbances, but inthis case the largest random disturbances with which the signal must compete originate generally not inthe receiver itself but elsewhere inspace. 
 If the nonlinear FM is symmetrical in time, the ambiguity  diagram has a single peak rather than a ridge. (A symmetrical waveform means the frequency  increases, or decreases, during the first half of the pulse and decreases, or increases, during the  second hair.) The nonlinear FM is thus more sensitive to doppler-frequency shifts and is not  doppler-tolerant. The surface-acoustic-wave delay line is one method for generating the non­ linear FM waveform and for acting as the matched filter. 
 OUTPUT SIGNAL 
 4. Berkowitz, R. S. 
 RELATED DATA IS NORMALLY BROAD 
 2.The extension ofcoverage beyond 186 miles isforsome reason important. Echoes from targets beyond that range constitute valuable information that ought tobesorted out and presented unambiguous y. IfCase 1applies, the difficulty can hardly beregarded asfunda- mental. 
 127  12.2.4 Receiver and Signal Processor Considerations ..................................................... 129  12.2.5 Design Example .................................................................................................... 130  12.2.6 Results ................................................................................................................... 
 ATE PULSE 
 K. Li, W. Ricketts, A. 
 Berger. F. B.: The Nature of Doppler Velocity Measurement, IRE Trans., vol. 
 PARAMETER SCALE AND SHAPE  NORMALIZATION LOGIC  IN ORDER TO IM PROVE ITS EFFECTIVENESS  AT CLUTTER BOUNDARIES IF THE PROBABILITY DISTRIBUTION OF THE CLUTTER AMPLITUDE IS NON 
 When used for both transmit  and receive, the phase shift must be changed between the two modes of operation. With  switching speeds of the order of microseconds, it is practical to reset the phase shifters just after  transmission in order to receive. They are then reset just before transmitting the next pulse. 
 Note that the quantity plotted is the rms value of the clutter-to-noise ratio. A pencil-beam antenna pattern is as- RANGE OF MAIN-BEAM CENTER (nml) FIG. 17.18 Dynamic-range example.MEDIUM PRF CONSTANT-GAMMA CLUTTER MODEL RADAR TARGET RANGEEXAMPLE RADARALTITUDE = 1 kft ALT= 15 kftALT = 5 kft PROBABILITYOF DETECTION FORTARGETAT LOWALTITUDE(TARGETALTITUDE * O)C/Nmax (dB) ALTITUDE SINGLE-SCAN PROBABILITYOF DETECTION (%) . 
 &- WAVE 
 *  It has been observed that some phased array radars have poor clutter rejection, which is often caused by failure   to follow rule 1. ch02.indd   94 12/20/07   1:52:14 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 J.: "Radar Observation of the Atmosphere," University of Chicago Press, 1973. 11. Doviak, R. 
 DOPPLER RADARS SUCH AS CIVIL MARINE RADARS  ALTHOUGH SUCH RADARS ALSO HAVE BEEN MANU 
 SURFACE SLOPE  IS DERIVED BY TAKING THE DIFFERENCE BETWEEN TWO NEIGHBORING  HEIGHT MEASUREMENTS  WHERE THE SLOPE TANGENT EQUALS hRISE OVER RUNv 4HE KEY WORD FOR THESE MEASUREMENTS IS  PRECISION THE STANDARD DEVIATION NOISE  OF THE SEA 
 29. Fuller, W.: "An Introduction to Probability Theory and Its Applications," 2d ed., vol. 1, p. 
 7, pp. 993-1003, November 1972. 72. 
 TIONAL MONOPULSE FEED 4HE !.-01 
 1940  Different radar equipments are developed in the USA, Russia, Germany, Fran ce  and Japan.     The reasoning to use of electric magnetic waves to the locating of  ships has been registered of the engineer of Düsseldorf, Christian  Hülsmeyer, already 1904 in Germany and England as a patent.    One finds the illustration in the patent sp ecification of a steamer  which detects an approaching ship with help of the backscattering. 
 The vision of the future is that Radar and synthetic aperture transmitters will be implemented as  arrays of modules, each one composed of:   DDS (Direct Digital Synthesizer) up -converte r, medium power amplifier antenna as  shown in Figure 14.1    Direct Digital Synthesizer Configura - tionSoftwarePre- amplifi - erMixerLow loss antenna High Efficien - cyPower AmplifierHPA   Figure 14.1  Block diagram of a single channel SDRS transmit subsystem    . Radar System Engine ering  Chapter 13 – Future Radar Systems  163     These modular transmit subsystems can be arranged to arrays much more flexible than Phased  arrays because of the simple and  only digital control. In addition a true time delay can easy be  digitally controlled. 
 with a target depth D of 7 m and a frequency-agile bandwidth of  300 MHz. the glint error is reduced by a factor of 2.6. According to the above, the improve-  merit in trackin accuracy is proportional to the square root of the frequency agility band-  width. 
 M.: DOPLOC Uses Phase-locked Filter, Electronic Ind., vol. 18, pp. 96-99, October,  1959. 
 Itcan, however, beused toproduce slowly varying sine and cosine voltages. These canthen beused tomodu- late alternating current ofproper frequency toprovide therequired volt- age components forasynchro-controlled servomechanism. The method Coae c1Modulator ?5A%line voltage ModulatorRAmplifier --Motor ~’ 0Data transmitter orPPIcoil (a)Cose Double clamp LAmplifier moCRT xSquare ~ wave :‘cFAmplifier Double clamp TSm.9 (b) F:~. 
 1.35 t01,5Commonly used ecreens P-1 P-1 P-1 P-1 P-7 P-1, P-7 P-7, P-12, P-14 P-lo P-1 P.1, P-7, P-12, P- P-7, P-12, 1’-14 P-1, P-7 P-7, 1’-12, P-14 P-7, P-12, P-14 P-1, P-7 P-74 ●Mont magnetic tubes actually give fmm 0.5 to0,7ofthis maximum spot size. Electrostatic tubm areingeneral near the maximum. Asaresult ofthese factors, electrostatic tubes areinvariably used for deflection-modulated indicators, but, except incases ofextreme weight limitation, magnetic tubes areused formost intensity-modulated displays. 
 Inaddition tospecially shaped condensers such asthat ofFig. 13.7, more conventional ones aresometimes used with rapid scanners, inorder. 490 THERECEIVING SYSTEhf—INDICATORS [SEC. 
 TIVELY SLOWLY COMPARED TO LAND VEHICLES AND AIRCRAFT )N ADDITION  SEA CLUTTER EXHIBITS BOTH CURRENT AND WIND 
 Watson-  Watt concluded that this type of death ray required fantastically large amounts of power and  could be regarded as not being practical at that time. Instead, he recotnmended that it would  be more promising to investigate means for radio detection as opposed to radio destruction.  (The only available means for locating aircraft prior to World War IE were sound locators  whose maximum detection range under favorable conditions was about 20 miles.) Watson-  Watt was allowed to explore the possibilities of radio detection, and in February, 1935, he  issued two memoranda outlining the conditions necessary for an effective radar system. 
 This signal ispassed through anetwork whose voltage response isequivalent tothe current response ofthe deflection- coilcircuit, and from there tothefirst stage ofahigh-gain amplifier. The grid ofthefirst amplifier tube issobiased that intheabsence ofsignal it + ITT2 Rectangular 4+ u: wavefofm generator Sawtmth ~: sweep waveform A generator I I ,, Transmitter (C’)?’1‘zi trigger A AIntensifying swnal outSynchro +TJ’ -4LA--.--.. Alternative waveform for——— AandB FIG. 
 However, some improvements that were applied to H 2S sets, such as slant-to- plan range correction of the PPI display and roll-stabilised scanners, were not incorporated in ASV Mk. III or ASV Mk. VI. 
 However, when the reciprocal of the signal  bandwidth is comparable with the time taken by a radar wave to transverse the antenna  aperture, bandwidth cfTccts can be important and signal distortion may result.  7.3 PARABOLIC-REFLECTOR ANTENNAS  One of the most widely used microwave antennas is the parabolic reflector (Fig. 7.6). 
 PulseMethods.—The pulse methods analogous tothose just discussed would consist oftheuseoftwo continuous trains ofpulses derived from sinusoids ofequal orcommensurate frequencies, one being shifted in phase with respect totheother. This would require theuseofatleast one subcarrier with wide sidebands, and therefore would beexpensive inthe )-M. Totransmdter Frequency mult)pller (a) Fromreceiver Filter I Videoand trigger + 4 -o‘““1To DataFrequency /0 indicator transmittermultiplier A.fFilter A.fFilter andfilter nfo --+-1 Pbll’Scan J Phase Phase nfo cnnvetier shifter comparator I J (b) FIG. 
   PP n  -ARCH   * , !LLEN ET AL  h0HASED ARRAY RADAR STUDIES v -)4 ,INCOLN ,AB 4ECH 2EPT   -ARCH   * , !LLEN AND " , $IAMOND  h-UTUAL COUPLING IN ARRAY ANTENNAS v -)4 ,INCOLN ,AB 4ECH  2EPT   /CTOBER   2 7 "ICKMORE  h.OTE ON EFFECTIVE APERTURE OF ELECTRICALLY SCANNED ARRAYS v  )2% 4RANS  VOL !0 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar.  METEOROLOGICAL RADAR  19.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 An efficient moment estimation technique was originally described by Rummler 84  and reinterpreted by Doviak and Zrnic.23 This estimator makes use of the fact that the  complex autocorrelation function of the received signal has the general form  R nT P nT jvnTr ( ) ( ) exp =  ρπ λ4 (19.36) where r(nT) is the correlation coefficient of the time series data and nT is the   time lag. 
 As the beam is scanned, every point on the plot is translated in  the same direction and by the same distance as is the beam maximum. The region inside the unit circle where  cos c os2 21 α αx y + ≤  FIGURE 13.8  Planar-array-element geometry and phasing FIGURE 13.9  Projection of points on a hemisphere onto the plane  of the array ch13.indd   16 12/17/07   2:39:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 NEER WAS THE  3EASAT 3!2 &IGURE  
 Theconcept ofdirective radiation fromfixed(nonsteered) phased-array antennas was knownduringWorldWarI.'Thefirstuseofthephased-array antenna incommercial broad­ castingtransmission wasintheearly thirties2andthefirstlargesteereddirective arrayforthe reception oftransatlantic short-wave communication wasdeveloped andinstalled bytheBell Telephone Laboratories inthelatethirties.JInWorldWarII,theUnitedStates,Great Britain,andGermany allusedradarwithfixedphased-array antennas inwhichthebeam wasscanned bymechanically actuated phaseshifters.IntheUnitedStates,thiswasanazimuth scanning S-band firecontrol radar,'theMark8,thatwaswidelyusedoncruisers and battleships,4 andtheAN/APQ-7 (Eagle)high-resolution navigation andbombing radarat Xbandthatscanned a0.50fanbeamovera600sectorinItseconds.sTheBritishusedthe phasedarrayintwoheight-finder radars,oneatVHFandtheotheratSband.6TheGermans employed VHFradarswithfixedplanarphasedarraysinsignificant numbers.7Oneofthese, 278. called [tic Murii~iiut. was lo() ft wide :tr~cl 30 ft high and scanned a 10" beam over a 120" sector. 
 The diagram of Fig. 9.5 is a parallel configuration. Series or series-parallel  configurations are po~sible.~'  The branch-type duplexer is of limited bandwidth and power-handling capability, and has  generally been replaced by the balanced duplexer and other protection devices. 
 IN CLUTTER RETURNS ON ADAPTIVE WEIGHTS BY SIMPLY SELECTING FOR ADAPTATION THE CLUTTER 
 D. Howard, “The effects of automatic gain control performance on the track - ing accuracy of monopulse radar systems,” Proc. IRE , vol. 
 Z. Li et al., “Soil moisture measurement and retrieval using envisat asar imagery,” Proc.  IGARSS04 , vol. 
 A. Gurnett, D. L. 
 CURRENT CONTRIBUTIONS   4HUS  LIKE +ELLERS  8 AND  9  -ICHAELIS DIFFRACTION COEFFICIENTS BECOME SINGULAR IN THE TRANSITION REGIONS ALONG . 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 26.2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 text displays, including exporting computed data in several formats for import into  other applications. 
 Simulations indicated that it provided 2D images with lower azimuth sidelobes compared with some existing azimuth suppression methods. The analysis presented here is idealized, since it assumes flight passes whose center positions are collinear and equally spaced, which would in practice be difficult to satisfy. Future work will analyze the effects of relaxing these conditions. 
 45. J. D. 
 "EAM 4UBE 3TRUCTURES  &IGURE  ILLUSTRATES  THE BASIC STRUCTURE OF THE 2& CIRCUITS THAT CHARACTERIZE THE VARIOUS TYPES OF LINEAR 
 The amplitude E1 of the received signal is proportional to the two- way antenna field intensity. The phase advance is 4rrVxTp sin O 2T1 = 2itfdTp = ^ (16.8) A. where fd = doppler shift of scatterer [Eq. 
 The CPR was devel - oped jointly by NASA and the Canadian Space Agency. It is a 94 GHz nadir-viewing  real aperture radar, transmitting 3.3 µsec pulses at a PRF of 4.3 kHz to fill a window  from the surface to 25 km altitude with 500-m vertical resolution sounding data. The  antenna diameter, limited by the launch vehicle shroud, is 1.95 m, which supports  across-track and along-track resolutions of 1.4 km and 2.5 km, respectively. 
  BUT 
 17. Skowron. J. 
 1. Radar. I. 
 4IME !DAPTIVE 0ROCESSING   2 +LEMM ED   ,ONDON  )%%    PP n  ( ,EE  h%IGENVALUES AND EIGENVECTORS OF COVARIANCE MATRICES FOR SIGNAL CLOSELY SPACED IN  FREQUENCY v )%%% 4RANS  VOL 30n  NO   PP n  /CTOBER   3PECIAL )SSUE ON 3UPERRESOLUTION  4HE ,INCOLN ,ABORATORY *OURNAL  VOL   NO   PP n  3 4 3MITH  h3TATISTICAL RESOLUTION LIMITS AND COMPLEXIFIED #RAMER 
   -ODELS OF THE '02 SITUATION RANGE FROM A SIMPLE SINGLE FREQUENCY EVALUATION OF PATH LOSSES TO COMPLETE $ TIME 
 BIT QUANTIZATION  )MAGERY WAS GENERATED BUT NOT IMMEDIATELY o  BY EITHER OPTICAL OR DIGITAL PROCESSING METHODS 4HE 3EASAT SATEL 
 S. Berkowitz (ed.), Modern Radar: Analysis, Evaluation and System Design , New York:   John Wiley & Sons, 1966.  5. 
 122 tion system, thedisplay circuits canbeidentical with those oftheB-scope ofFig. 12.1. Figure 12”3 shows the parts necessary toconvert Fig. 
 L Switch 31C0/4sec 1A,VIB & flipfbp16/I sec- Fig.16.3 V5B,V6 (Fig.16.3)delay circuit I o I 1 1II ~Upperbeamvideo IPLock.overVideo switchIBeaconvideo- II / L–––– ——– —–_—~–~flr– ________—––d ground radar relay.. 730 RADAR RELAY [SEC.17.15 thesecond receiver contain thecoded modulator pulse, theazimuth pulse, and thebeacon switch pulse. They pass through aswitch which excludes allsignals while video isbeing transmitted but opens shortly before the arrival ofatrigger pulse. 
 K. Reedy: "Principles of Modern Radar," Van Nostrand Reinhold Company, 1987. 10. 
 The other approach simultaneously transmits two frequencies  f1 andf2• and the receiver is tuned to a strong cross-product such as 2f1 ±!2• When receiving  at a frequency different from that transmitted, care must be exercised to ensure that the  transmitter signal does not radiate a significant spectral component at the frequency to which  the receiver is tuned.  The amount of signal returned from a nonlinear contact at a harmonic frequency is a  nonlinear function of the incident field strength. Thus the nonlinear target cross section  depends on the power, and the normal radar equation does not apply. 
 A path factor enhancement of 6 dB has been chosen as a representative value of construc - tive multipath interference for an aircraft target. The beamwidth has been taken to be  5.7° and the surface scattering coefficient to be –35 dB, and with a 12 dB path enhance - ment, the clutter level has been plotted. The clutter-to-noise ratio (CNR) at 1000 nmi is  about 88 dB. 
 D. E. Barrick, “Theory of HF and VHF propagation across the rough sea, pts. 
 ENTROPY METHOD -%-  INVENTED BY * 0 "URG )T WORKS WELL WITH A (OWELLS 
 For example, a radar set having a pulse length of 1 microsecond will have aminimumrangeof164yards.Thismeansthattheechoofatargetwithinthisrange will not be seen on the radarscope because of being masked by thetransmitted pulse. Since the radio-frequency energy travels at a speed of 161,829 nautical miles per second or 161,829 nautical miles in one million microseconds, thedistance the energy travels in 1 microsecond is approximately 0.162 nauticalmile or 328 yards. Because the energy must make a round trip, the targetcannot be closer than 164 yards if its echo is to be seen on the radarscopewhile using a pulse length of 1 microsecond. 
 1977.. 570 1NTRODUCTlON TO RADAR SYSTEMS  95. Tischer, F. 
 Lanari, Synthetic Aperture Radar Processing , Boca Raton, FL: CRC  Press, 1999. 33. R. 
 BASED ALTIMETER SYSTEMATICALLY CIRCLES THE %ARTH  GENERATING SURFACE  HEIGHT MEASUREMENTS ALONG ITS NADIR TRACK 4HESE MEASUREMENTS ACCUMULATE  PROVID 
 I, II, and III, New York: Academic Press, 1964.  5. N. 
  B6 1  
 20–21, April 1985. 76. J. 
 PULSE  "ARKER CODE IS   )T r   LOG ;   =T $D"    0ULSE 
 The loss ofbeacon signal inthe TR and ATR alone could beas much as15or20db. Inaddition, noautomatic frequency control ofthe beacon local oscillator was provided. Better facilities forworking with beacons were desired intheAN/APS-10. 
 However, the  disturbance to the aperture illumination can be quite large and can result in significant  differences from the pattern computed by ignoring such effects.  8.6 FEEDS FOR ARRA YS20·81-84  If a single transmitter and receiver are utilized in a phased array, there must be some form of  network to connect the single port of the transmitter and/or the single port of the receiver to  each of the antenna elements. The power divider used to connect the array elements to the  single port is called an array feed. 
 Avoltage s~p-up ofabout ~can beobtained inasingle cycle under these conditions, ifthe pulser isfired about 21° after the crest ofthe impressed a-c wave is reached. Maximum simplicity isachieved bymounting arotary spark gap directly onthe shaft ofthe a-cmachine exciting the network. Phasing iseasily accomplished bymechanical adjustment. 
 OFF IS LOWER -.2  AT THE EXPENSE OF BROADER IMPULSE RESPONSE WIDTH )27  4YPICAL DESIGNS PROVIDE  ^ EXCESS RANGE AND DOPPLER BANDWIDTH  RELATIVE TO THOSE IMPLIED BY THE REQUIRED RANGE AND AZIMUTH RESOLUTIONS TO ACCOM 
 This is accomplished by  automatic gain control (AGC) to keep the sum signal output and angle-tracking loop  gains constant for stable automatic angle tracking. Figure 9.3 is a block diagram of typical monopulse radars. The sum signal, eleva - tion difference signal, and azimuth difference signal are each converted to intermedi - ate frequency (IF), using a common local oscillator to maintain relative phase at IF. 
 This value is for isotropic radiators and is reduced if the radiators  have directivity. Linear Array.37 With a linear array of N isotropic radiators, excited with equal  amplitudes and phase and separated by distances s, as shown in Figure 13.5, the con - dition for the occurrence of grating lobes is unchanged from the simpler case just  considered. They occur for the same values of p (s/l) sin q, but the width of the lobes  is reduced, and they are separated by minor lobes. 
 394 INTRODUCTION TO RADAR SYSTEMS  rank detector which computes the ranks by pair-wise comparisons of the qutput from the range  cell under test with each of the outputs from the neighboring range cells that sample the  background noise. 78-81 After the detector ranks the sample under test with its neighboring  samples, it integrates the ranks and a target is declared arter testing against a fixed and an  adaptive threshold. 80•81  There are several other methods for achieving CF AR besides the use of cell averaging. 
 This timing places  a further constraint on the pulse repetition frequency. It turns out that the nadir return  may not be avoidable if other constraints override the available PRF options. This  occurs, for example, if the driving requirement is ScanSAR, which has its own set of  constraints on PRF. 
 153. A. V . 
 HORN SQUARE FEED SEE &IGURE   SUBTRACTS THE OUTPUT OF . °{  2!$!2 (!.$"//+  THE LEFT PAIR FROM THE OUTPUT OF THE RIGHT PAIR TO SENSE ANY UNBALANCE IN THE AZIMUTH  DIRECTION )T ALSO SUBTRACTS THE OUTPUT OF THE TOP PAIR FROM THE OUTPUT OF THE BOTTOM PAIR TO SENSE ANY UNBALANCE IN THE ELEVATION DIRECTION )N ADDITION  THE CIRCUITRY ADDS THE OUTPUT OF ALL FOUR HORNS FOR A SUM SIGNAL FOR DETECTION  MONOPULSE PROCESSING  AND RANGE TRACKING 4HE COMPARATOR SHOWN IN &IGURE  IS THE CIRCUITRY THAT PERFORMS THE ADDITION AND  SUBTRACTION OF THE FEED HORN OUTPUTS TO OBTAIN MONOPULSE SUM AND DIFFERENCE SIGNALS )T IS ILLUSTRATED WITH HYBRID 
 Asindicated in Fig. 13.1 thesame type offield isusually used forfocusing and deflection inagiven tube. 1 10ccasionally electrostatic focusing iscombined with magnetic deflection; such tubes have notcome intowide useinthiscountry. 
 At this meeting Lovell states that it was agreed that 50 3cm sets would be reserved for Coastal Comm and. However, he also notes that Bomber Command was ‘enraged ’by this decision. This meeting ev idently immediately preceded the planning meeting, minuted in [ 1], that set out the equipment to be produced. 
 TIfEELECTRONICALLY STEERED PHASED ARRAY ANTENNA INRADAR337 beenofconsiderable interest, butitcanalsobeaseriousliability insomeapplications. The preferred frequency foraground-based aircraftsurveillance radarisatthelower portionofthe microwave region(UHForLband).Themajorfactorsofimportance thatfavorthelower frequencies forsurveillance radararethelargeaverage powerandthelargeantenna aperture. hathofwhichareeasiertoobtainatthelowerfrequencies. 
 The aperture distribution has been defined in terms of the current ix. It may also be  defined in terms of the magnetic field component Hz for polarization in the x direction, or in  terms of the electric field component Ez for polarization in the z direction, provided these field  components are confined to the aperture.7  The expression for the electric field intensity [Eq. (7.10)] is mathematically s.iJnilar to the  inverse Fourier transform. 
 indium phosphide (InP) and operate as millimeter-wave oscillators. Silicon de- vices offer the most promise because silicon provides the most efficient junction heat removal. Overall performance of the diode depends upon the doping density and the thicknesses of the epitaxial, junction, and interface layers. 
 Elevation Error Due to Surface Reflections.* One of the fundamental factors limiting the height accuracy in all height finding techniques that depend on elevation-angle measurements is the elevation-angle accuracy degradation due to the multipath from surface reflections. Such surface reflections vectorially combine with the direct-path signals entering the antenna to produce amplitude and phase variations which ordinarily cannot be separated from the direct-path signals. In general, the magnitude of such elevation-angle errors is such that, at low elevation angles where an appreciable portion of the antenna beam is directed into the ground, the elevation-angle errors are prohibitively large. 
 The entropy curves of the wide-area image and the local image are shown in Figure 12a,b, respectively. 83. Sensors 2019 ,19, 1920   (a) ( b)   3XOVH1XPEHU(QWURS\ G% ))7 5(/$; $3(6 3URSRVHG   3XOVH1XPEHU(QWURS\ G%   ))7 5(/$; $3(6 3URSRVHG Figure 12. 
 The maximum slope occurs for a value 8,/OB slightly greater than  0.4. This corresponds to a point on the antenna pattern (the antenna crossover) about 2 dB  down from the peak. It is the optimum crossover for maximizing the accuracy of angle  tracking. 
 Ambiguitie5 may be avoided with a single-pulse waveform  rather than a periodic-pulse waveform. Although the accuracy of simultaneously measuring  time and frequency with a simple pulse-modulated sinusoid was seen to be limited, it is  possible to obtain simultaneous time and frequency measurements to as high a degree of  accuracy as desired by transmitting a pulse long enough to satisfy the desired frequency  accuracy and one with enough bandwidth to satisfy the time accuracy. In other words, the  peak at the center of the ambiguity diagram may be narrowed by transmitting a pulse with a  large bandwidth times pulse-width product_(large pa). 
 Because of antenna size constraints, operating frequencies have generally been in the C, X, or K^1 bands. The increased availability of components at higher frequencies has permitted operation at Ka and millimeter-wave frequencies in later-generation systems. The nature of missile systems and the environment in which they are devel- oped result in evolutionary changes rather than revolutionary innovations. 
 9.24. Itisattheintersection of four waveguides. When thevane ofthe switch isatone ofits45° positions the energy isdirected through the array in one direction and that 5to10percent of the energy which isnot radiated is routed into amatched load. 
 Perhaps more importantly,  although the flare itself is not predictable, the associated burst of particles will start to  arrive a few hours later, with most ejected material reaching Earth several days later,  seriously disrupting HF propagation. The critical importance of solar activity will be  demonstrated in Section 20.13 in the context of radar performance prediction. Ionospheric Dynamics. 
 TION BEAMS UNDELAYED  ONE 
 Such models provide a basis for understanding the behavior  of electromagnetic waves within these media. The real and imaginary dielectric losses  ch21.indd   18 12/17/07   2:51:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 BEAM CLUTTER REGIONS VARIES WITH CONDITIONS AZIMUTH IS MEASURED  FROM RADAR PLATFORM VELOCITY VECTOR TO THE ANTENNA BORESIGHT OR TO THE LINE OF SIGHT TO THE TARGET  HORIZONTAL 
 This work is published with the understanding that McGraw-Hill and its authors are supplying information but are not attempting to render engineering or other professional services. If such services are required, the assistance of an appropriate professional should be sought. CONTRIBUTORS Lament V. 
 All such extracts are copyright of IEC, Geneva, Switzerland. All  rights reserved. Further information on the IEC is available from www.iec.ch. 
 MEDIUM 02& WHICH WILL  BE DISCUSSED LATER   IS CHARACTERIZED AS HAVING ONLY A SINGLE 
 In all cases, small targets (e.g. RCS of 10 dBm 2) would have been invisible at all ranges except in very low sea states. It is also interesting to note in ﬁgure 7.5the behaviour in sea state 2 at short range. 
 I., G. Nemhauser, and J. W. 
 Theeffectofweighting thereceived-signal spectrum tolower thesidelobes alsowidensthemainlobeandreducesthepeaksignal-to-noise ratiocompared totheunweighted linearFMpulsecompression. Thislossisduetothefilternotbeing matched tothereceived waveform; thatis,thefilterissaidtobemismatched. Thustoreduce thesidelobes toalevelof-30to-40dBresultsinalossinpeaksignal-to-noise ratiooffrom onetotwodB.Formanyapplications thebeambroadening andthelossinpeaksignal-to­ noiseratioduetomismatch areusuallytolerated inordertoachievethebenefitsofthelower sidelobes. 
 The losses due to water layers on radomes have  been calculated by Blevis." 6q1 l7  Theory predicts that a w/h-~ain will produce a layer of water 0.142 mm thick on a  55-ft diameter radorne. The theoretical loss through such a water layer is 1.5 dB at 4.2 GHz  and 4.4 dH af'9.36 (;Hz. Ruze'" confirmed Blevis's calculations and noted that a nonuni-  forrrily wet radome can cause significant phase perturbations in the aperture illumination, as  well as a transmissio~i loss. 
 MODULATED ,&-   PULSES AT  7 PEAK POWER FROM COMBINED 'A!S &%4 DEVICES /NLY  ONE ANTENNA IS  ACTIVE FOR  S  AT A TIME THE OPERATION CYCLES AROUND THE SIX ANTENNAS IN SEQUENCE 4HE INSTRUMENT MASS IS  KG INPUT POWER REQUIRED IS  7 4HANKS TO ONBOARD PROCESSING  THE INHERENT DATA RATE IS REDUCED FROM  -BITS TO AN AVERAGE OF  KBITS TO THE -ET/P 
 STAGE SHIFT REGISTER DENOTED BY THE  $S  BLOCK  AND A SUBTRACTOR 4HE COMB FILTER GETS  ITS NAME BECAUSE ITS FREQUENCY RESPONSE LOOKS LIKE A RECTIFIED SINE WAVE AND RESEMBLES THE TEETH OF A COMB !FTER THE COMB STAGE  THE SIGNAL IS DECIMATED BY A FACTOR  2 DENOTED  BY THE m2 BLOCK  BY ONLY PASSING EVERY  2 TH SAMPLE )N MOST APPLICATIONS  THE NUMBER  OF STAGES IN THE SHIFT REGISTER   $  IS EQUAL TO THE RATE CHANGE FACTOR   2 &IGURE B  DEPICTS A #)# INTERPOLATOR  WHERE UPSAMPLING BY A FACTOR OF  2 DENOTED BY THE  k2 BLOCK   IS FOLLOWED BY A COMB SECTION AND AN INTEGRATOR 4HE UPSAMPLING IS ACCOMPLISHED BY ZERO INSERTION AS DESCRIBED IN THE PREVIOUS SECTION  h)NTERPOLATION &ILTERSv .OTE THAT THE PROCESSING ONLY CONSISTS OF DELAYS AND ADDS &IGURE A SHOWS THE SINX X FREQUENCY RESPONSE OF A SINGLE 
 which is the same as the output from the double-delay-line canceler.  f (t) - f (t + T) -f (t + T) +f (t + 2T)  This configuration is commonly called the three-pulse canceler.  Transversal filters The three-pulse canceler shown in Fig. 
 7.3 Further, thescreen must bewell shielded from stray light ifthis method istobeused, and this somewhat limits itsusefulness. Televising the persistent screen and using the video signals so obtained tomodulate ahigh-intensity short-persistence tube suit- able forprojection. The results obtained with thk rather com- plicated scheme uptothe end ofthewar were mediocre. 
 In practice, however, the echo signal  from a target in motion is almost never constant. Variations in the echo signal may be caused  by meteorological conditions, the lobe structure of the antenna pattern, eqilipmerlt instabili-  ties, or variations in the target cross section. The cross sections of complex targets (the usual  type of radar target) are quite sensitive to aspe~t.~~,~~ Therefore, as the target aspect changes  relative to the radar, variations in the echo signal will result. 
 RD and IRD algorithm ﬂow charts. ( a) RD algorithm ﬂowchart; ( b) IRD algorithm ﬂowchart. 3. 
 This is called data stabilization. Correction of the data may still . RADAR ANTENNAS 271  be required even with some form of mechanically stabilized mounts. 
 We must also pay attention tothe reverse voltage V~,which most pulsers put across themagnetron after themain-power pulse has passed, forinsome cases V~l may belarger than V~Oand lead tobreakdown of the magnetron insulation. This same reverse voltage may also appear across various parts ofthe pulser circuit itself unless steps aretaken to suppress it. Most pulsers keep thereverse voltage within safe limits by means ofaresistance or,better still, anonlinear element such asadiode. 
 The difficulty inusing atriode lies infinding acircuit that isstable, uncritical inadjustment, yet with enough gain toswamp out noise originating inthe following stage. A circuit that hasrecently been developed isshown inFig. 12”5. 
 linear bound 99-detectorlinear 98- envelope detecfor 95- Median c90 detector2 U Q)Log Qj80 l:J envelopea70- detector ~60- .a500.0a40-d:30- 20 10 5- (" 10246810121416 18 20 Signal/median clutIer(dB} (bl example ofonesuchtechnique isthelog-FTC receiver.32Thisisareceiver withalogarithmic input-output characteristic followed byahigh-pass filter(onewithafasttime-constant, or FTC).Thelog-FTC hastheproperty thatwhentheinputclutterornoiseisdescribed bya Rayleigh pdf,theoutputclutterornoiseisaconstant independent oftheinputamplitude. Thusthelog-FTC receiverhasaconstant false-alarm rate.AswithanyCFAR,thefalse-alarm rateismaintained constant byasacrifice intheprobability ofdetection. (Afurtherdescription astowhythelog-FTC receiver isCFARwhentheinputisRayleigh dutterisgivenin Sec.13.8.). 
 IRE , vol.49, pp. 1184–1192, July 1961. 72. 
 The initial pre- ignition spike (Fig. 11.16)issoshort (less than 0.01 psec) that the heat cannot beconducted away from thecontact; consequently thetotal spike energy rather than the peak power isthe important quantity. Experi- ence has shown that burnout isfarmore likely tocome from the spike than from theflat. 
 Equation (8.32) is an optimistic estimate for  the peak lobe. The greatest phase quantization lobe is said to occur when the element spacing  is exactly one-half the phase quantization period or an exact odd multiple there~f.~~~"~ With  an element spacing of one-half wavelength, the quantization lobe will appear at sin 0, 2  sin 0, - I, with a value of  n2 1 cos 0, Peak quantization lobe cr - - - -- -  4 22B cos oo  The peak sidelobes due to the phase quantization can be significant, and attempts should  be made to reduce them if their presence is objectionable. One method for reducing the peak  lobe is to randomize the phase quantization. 
 Schwartz44 considered the effect of partial correlation for the case of  two pulses per scan (11 2). The results for partial correlation fall between the two extremes of  completely uncorrclatc<l and completely corrclate<l, as might be expected. Thus to estimate  0 99  098  0 95 .. 
 ENCE OF DOPPLER SHIFT 4HE AMBIGUITY FUNCTION OF A .,&- SINE 
 The receiver has one tuned r-fstage, amixer, alocal oscillator, seven i-fstages, two limiters, adiscriminator, avideo amplifier, and three tubes connected inparallel asacathode-follower output stage. Allthe tubes inthis section ofthereceiver are6AK5 miniature pentodes, except theoneused inthedk.criminator which isa6AL5 miniature double diode. The r-f,i-f,and video sections, aswell asthediscriminator, arestand- ard indesign, an8-Me/see bandwidth inthei-famplifier being obtained bydouble staggering ofalternate stages. 
 America too was making headway, and as early as the  autumn of 1922 Dr Hoyt Taylor and Leo C. Young  noticed a distortion, or ‘phase-shift,’ in the received  signals due to reflection from a small steamer on the  Potomac. To-day we should consider their results  remarkable, because the steamer had a wooden huii and  there was very little metal or conducting material im the  construction to accentuate such a phase-shift. 
 6.11. Height-finding Involving Ground Reflection.-The height of anaircraft target isusually determined byfinding separately itsrange and itsangle ofelevation, and then solving the equation H=Rsine. Inthe wartime use ofradar, height was such animportant datum that considerable ingenuity was expended onthe problem ofits measurement. 
 402 INTRODUCTION TO RADAR SYSTEMS  A/t,, where t, is t,he rise time. For large signal-to-noise ratios the slope of the pulse corrupted  by noise is essentially the same as the slope of the uncorrupted pulse. From Fig. 
   3/,)$ 
 !    "' 
 Golino, and L. Timmoneri, “Maximum likelihood estimator approach for the esti - mation of target angular coordinates in presence of main beam interference: Application to live  data acquired with a ground-based phased-array radar,” Proc. of IEEE 2005 Int. 
 For example, horizontal polarization mightbeemployed withlongrangeair-search radarsoperat­ ingatVHForUHFsoastoobtainlongerrangebecauseofthereinforcement ofthedirect radiation bytheground-reflected radiation, Sec.12.2.Circular polarization isoftendesirable inradarswhichmust"see"through weather disturbances. Sidelobe radiation. Anexample ofsidelobe radiation fromatypicalantenna wasshownin Fig.7.1.Lowsidelobes aregenerally desiredforradarapplications. 
 Amoresatisfactory method of operation istoformthesumanddifference patterns intheRFandtoprocessthesignalsasina conventional amplitude-comparison monopulse radar. Inoneembodiment ofrhephase-comparison principle asappliedtomissileguidance the phasedifference between thesignalsintwofixedantennas ismeasured withaservo-controlled phaseshifterlocatedinoneofthearms.27Theservo[oopadjuststhephaseshifteruntilthe difference inphasebetween thetwochannels isanull.Theamountofphaseshiftwhichhasto beintroduced tomakeanullsignalisameasure oftheangular error. Thephase-andamplitude-comparison principles canbecombined inasingleradarto produce two-dimensional angletracking withonlytwo,ratherthanfour,antenna beams.28 Theangleinformation inoneplane(theazimuth) isobtained bytwoseparate antennas placed sidebysideasinaphase-comparison monopulse. 
 The probletn consists in determining whether these rt pulses are due to  signal-plus-noise or wliether they are due to noise alone. The probability-density function for  the envelope of 11 independent noise sanlples is the product of the probability-density function  for each sarrlple, or  n  The probability-derlsity function for itll noise pulse pn(oi) is given by Eq. (2.2 I), rewritten  wl~ere I., i5 ttie ratio of the envelope amplitude R to the rms noise voltage Likewise, the  probability-derlsity fu~lctiorl for the e~lvelope of n signal-plus-noise pulses is  The probability-density function for signal-plus-noise, p,(vi), is the Rice distribution of  Eq. 
 SPONDING DOPPLER SHIFTS ARE THOSE ASSOCIATED WITH THE PHASE VELOCITY OF THE RESONANT WAVES  THAT IS   FGG F CF- ( ZD o  o yoPPK     WHERE  THE DOPPLER SHIFT  FD IS IN (Z G IS THE GRAVITATIONAL ACCELERATION  MS 
 Activation ofthe switch can becontrolled either by thesignals themselves (just asarectifier oranoverload relay iscontrolled) orbyastimulus independent ofthesignals. Initsaction theswitch can beeither aseries element analogous toavalve that opens and closes to block ortransmit the signals, oraparallel element that, when closed, holds apoint inthecircuit inaquiescent state regardless ofthepresence ofsignals. Clamps .—The name “clamp” isapplied toawide variety ofelectronic switches which, when closed, hold orclamp two circuit points together more orless rigidly. 
 (2.55) was derived for a rectangular pulse, it can be applied to other waveforms  as well, provided matched-filter detection is employed. Most calculations for probability of  detection with signal-to-noise ratio as the parameter apply equally well when the ratio of  signal-energy to noise-power-per-hertz is used instead. The radar equation developed in this  cliapter for pulse radar can he readily modified to accommodate CW, FM-CW, pulse-doppler,  MTI. 
 TRAL CONVOLUTION 7ELL SEE SHORTLY HOW THIS IS DONE IN HARDWARE  4HE RESULT  ON THE THIRD LINE  HAS SPECTRAL COMPONENTS CENTERED AT  -(Z AND   -(Z -ULTIPLICATION  BY THE LOWPASS 
 TERM FORECASTING OF THE PRECISE LOCATION AND LEVEL OF SEVERITY OF THESE PHENOMENA  THROUGH DATA ASSIMILATION AND NUMERICAL WEATHER PREDICTION TECHNIQUES  IS BEYOND THE PRESENT STATE OF THE ART /PERATIONAL RADARS  HOWEVER  CAN DETECT THESE PHENOMENA AND PROVIDE LOCAL WARN 
 If the input signal phase distor - tion is given by  f b( ) sin fnf B=  2π (6.54) where  b = peak phase ripple  B = waveform input bandwidth  n = number of cycles of phase ripple the resulting output distortion produces range sidelobes at times ±n / MB and magnitude  20 log10(Mb / 2) relative to the main beam of the target return. As an example, generat - ing a chirp waveform that has range sidelobes better than 35 dB using an ×8 multiplier  requires that the input signal has less than 0.5 degrees peak-peak phase ripple. Frequency multipliers can be implemented using a variety of techniques, such as  using step recovery diode multipliers or using phase locked loops. 
 Theselosses,denoted Lu,mightbeduetothe receivertransmission line,duplexer, rotaryjoint,preselectorfilter,monitoring devices,orloss intherandome. ThenoisefigureduetotheseRFlossesmaybederivedfromthedefinition of Eq.(9.1),whichis NOUI Fn=kT,BGon(9.1) ThenoiseNou,fromthelossyRFcomponents iskToBn,andG=1/4F'Therefore onsubsti­ tutionintoEq.(9.1),thenoisefigureFLduetotheRFlossesissimply (9.14). RECEIVERS, DISPLAYS, AND DUPLEXERS 351  The noise figure of a receiver with noise figure F,, preceded by RF losses equal to L,, is  F2 - 1 F - F1 + o - = LRF + (Fr - 1)LRF = FrLRF (9.15)  GI  where F, = kF, GI = I/LRFr and F2 = F,. 
 BIT WORDS  TO SERIAL DATA LINKS  WHICH PASS SINGLE BITS AT VERY HIGH CLOCK RATES CURRENTLY IN EXCESS OF  GIGABITS PER SECOND 'BPS   4HESE SERIAL DATA LINKS  ARE TYPICALLY POINT 
 Figure 16.18 shows the residue for the case when the frac- tion of the horizontal aperture width a traveled per interpulse period Tp, Vn = VxTp/ay is equal to 0.04 and when the number of wavelengths that the ap- erture tip rotates per interpulse period, Wn = cn$rTpl2\, is equal to 0.04. The cor- responding improvement factor is 52 dB. The improvement factor is shown in Fig. 
 319-329, June, 1957.  49. Skolnik M. 
 A FILTER FOR RADAR TRACKING  ONE USES THE RADAR PARAMETERS TO CA LCULATE  THE TRACKING ERRORS LISTED IN 4ABLE  AS A FUNCTION OF THE TRACKING GAINS  @ AND A  4HEN ONE SELECTS THE GAINS THAT BEST MEET THE NEEDS OF THE APPLICATION &OR EXAMPLE  CONSIDER A RADAR THAT HAS  
 10. B. Nilsson, “Two topics in electromagnetic radiation field prospecting,” Ph.D. 
 107 orgaseous discharge, inthis circuit. When this isdone, however, another difficulty presents itself immediately: thecurrent flow through agaseous discharge switch cannot beinterrupted atwill, sothat allthe energy stored must bedissipated inthe load. Ifthe energy-storage element is still acondenser, then itscapacity Cocould bemade ofsuch amagnitude 0.75 IIRL=2Z0--1 R,=Z.~0.50 t v’ 70~L=* .— 0.25 .-1 I I I L----.l ~.–-4----1 0“ i‘o2;70 3>---7’00 i t L-. 
 #/5.4%2-%!352%3   Ó{°Î RESORTING TO FREQUENCY AGILITY ANDOR FREQUENCY DIVERSITY 3OME RADARS INCORPORATE AN  !&3 DEVICE THAT ALLOWS THE RADAR FREQUENCY TO BE TUNED TO THAT PART OF THE SPECTRUM CONTAINING THE MINIMUM JAMMING ENERGY   )N ACCORDANCE WITH THE SEARCH 
                            &)'52%   2ANGE 
 Antenna theory gives the relationship between the transmitting gain and the receiving  effective area of an antenna as  ( 1.8)  Since radars generally use the same antenna for both transmission and reception, Eq. ( l .8) can  be substituted into Eq. (1.7), · first for Ae then for G, to give two other forms of the radar  equation  ( l.9)  ( l.10)  These three forms (Eqs.· 1.1, 1.9, and 1.10) illustrate the need to be careful in the inter­ pretation of the radar equation. 
 46. Straiton, A. W., and C. 
 Asthisisgenerally trueofmostwaveguide feeds,aperfectly symmetrical antenna pattern isdifficult toachieve inpractice. Therectangular guidcmaybeused,however, for feedingallasymmctrical sectionofaparaboloid thatgenerates afanbeamwiderintheJl planethanintheEplane. Whenmoredirectivity isrequired thancanbeobtained withasimpleopen-ended waveguide, someformofwaveguide hornmaybeused.Thewaveguide hornisprobably the mostpopular methodoffeedingaparaboloid forradarapplication. 
 Keehan, and C. J. Tidwell, “History of the Terminal  Area Surveillance System (TASS),” in  28th Conf. 
 This can be done . MTI AND PULSE DOPPLER RADAR 147  adaptively. A separate set of filters is required for each range gate. 
 The tuning piston can be positioned  mechanically from the outside of the vacuum by means of a vacuum bellows. In the coaxial magnetron, the output of every other resonant cavity is coupled to the  stabilizing cavity that surrounds the anode structure. The output power is then coupled  from the stabilizing cavity. 
 The trend was generally downward as p increased. Values for horizontal and vertical polarization showed no significant differences. For the most part both monostatic and bistatic data exhibited nearly log-normal amplitude distributions. 
   
 OF 
 Note use of g  (with an arbitrary reference) instead of s 0 for the ordinate.  (after D. H. 
 /Ê " 
 Hansen, V. G., and A. J. 
 W. Love (ed.), Electromagnetic Horn Antennas , New York: IEEE Press, 1976. 37. 
 The resulting clutter residues after the MTI  canceler must, therefore, be further suppressed to prevent saturation of the PPI display  and/or an excessive false-alarm rate in an automatic target detection (A TD) system. Against spatially homogeneous sources of clutter such as rain, sea clutter, or corri - dor chaff, a cell-averaging constant-false-alarm-rate (CA-CFAR) processor following  the MTI filter will usually provide good suppression of the clutter residues. Special  features are sometimes added to the CA-CFAR, such as greatest-of-selection or two- parameter (scale and shape) normalization logic, in order to improve its effectiveness  at clutter boundaries if the probability distribution of the clutter amplitude is non- gaussian. 
 CRESTED LOW 
 If  sensitivity to frozen volatiles is a requirement levied on a planetary exploratory radar,  then the system should be dual-polarized and must transmit circular polarization. As  reviewed in Section 18.2, a dual-polarized radar maximizes its measurement capabili - ties only if it retains the relative phase as well as the magnitudes of the two received  amplitudes, such as EH and EV in the linear polarization basis. It has been known since  1852 that a quasi-monochromatic EM field can be fully characterized by the four Stokes  parameters.116 In terms of linearly polarized received data, the Stokes parameters are   S E E S E E S E E SH V H V H V12 2 22 2 3 42= + = − = = −| | | | | | | | Re* 2 2Im*E EH V (18.19) where * denotes complex conjugate, and the carats < > indicate an average taken over  several samples. 
 In one sense. the development of HF skywave radar can be traced back to the 1920s,  when skywave echoes were identified,1 but the first HF radar systems were not deployed  until the 1950s.2 Since then, skywave radar has evolved to address applications such  as the detection and tracking of aircraft, ballistic and cruise missiles, and ships.3–15 In  addition to detecting “skin” echoes from targets of interest, HF radar is useful for observ - ing various forms of high-altitude atmospheric ionization, both natural, including those  associated with aurorae and meteors, and artificial, including the interaction of space - craft and ballistic missiles with the ionospheric plasma.16–19 Further, the wavelengths  used are of the same order as ocean surface gravity waves, and this correspondence can  be exploited to provide information on the wave directional spectrum, ocean currents,  and, by inference, surface winds.5 Indeed, scattering from the sea can often be employed  as a radar cross section (RCS) amplitude reference and is a widely used diagnostic tool.  The narrow-band waveforms employed, the low frequencies, and the nature of the trans - mission path make the spatial resolution coarse when compared with higher-frequency  radars, but the doppler resolution can be exceedingly fine. 
 The choice of range as the independent variable may seem artificial, but it is a useful approach for performance examination. With these curves the impact on radar SNR performance can be estimated for GREAT-CIRCLE TIME DELAY (ms) GROUND RANGE (nmi) . F R EQU ENCY(MHz)" FIG. 
 The echo from the sea with horizontal polarization can be neglected at the smaller grazing angles. The water wavelengths between 10 and 100 m are gravity waves that in deep water follow the dispersive relation [jeLli/2 v = Hr <24'2>L2irJ where v = water-wave phase velocity g = acceleration of gravity L = water wavelength Ocean waves are excited by the surface winds. If a wind blows at a constant velocity long enough and over sufficient fetch, a steady-state condition will be achieved where the wind provides just enough energy to the water to supply that lost in breaking and other dissipation. 
 First, because of attenuation it becomes difficult, if not impossible, to make quantitative measurements of the backscattered energy from precipitation which is at greater range (and at the same azimuth and elevation angles) than precipitation closer to the radar. This inability to precisely measure the backscattering cross section makes quantitative measurements of precipitation rates more difficult. Second, if the attenuation due to precipitation or the intervening medium is sufficiently great, the signal from a precipitation cell behind a region of strong absorption may be totally obliterated, leading to potentially disastrous effects. 
 Instead,  in-orbit performance has been evaluated by computing  the standard deviation about a linear fit to IO-sample  (I-second) sets of height data, repeating this for 10 con­ secutive sets, and averaging the results. In this case, only  the surface variability over a much shorter I-second  (7-kilometer) span will affect the measurement. It hap­ pens that for the tracking-filter time constant used (0.25  second), the standard deviation about a fit to 10 sam­ ples is nearly the same as the standard deviation of the  average of 10 samples. 
 (11.20)A:€ sin 9 where a is the radius of the cylinder, € is its length, and 6 is the angle off broad- side incidence. Equation (11.20) includes only the contribution from the curved side of the cylinder and not its flat ends, which may be included by using the prescription of Eq. (11.19). 
 These parallel processor architectures offer the benefit of being programmable  using high-level languages, such as C and C ++. A related advantage is that program - mers can design the system without knowing the intimate details of the hardware.  Also, the software developed to implement the system can typically be moved rela - tively easily to a new hardware architecture as part of a technology refresh cycle. 
 Proj. 76 D-220, Final Rept . ER76-4414, December 30, 1976. 
 Ships arelessthan 300Y(Iapart. (Reprinted from Eleckmics, December 1945.) The AN/TPG-l rapid scan covered asector 10°wide centered onthe target ofinterest. The antenna could bemechanically rotated asawhole toswing thecenter ofthis sector toany desired azimuth position, orcould berotated continuously inazimuth during search. 
 It should be noted that most textbook analyses assume that the stalo instabil- ity is due either to a single modulation frequency or to a combination of white gaussian-noise modulations. Rarely are these assumptions valid for real stales; so a different method of analysis must be employed. NOISE LEVEL (dBc/Hz) CURVESINGLE-SIDEBAND SPECTRUMINTEGRATED DOUBLE- SIDEBAND NOISE (dBc) 1 STALO (COMBINATION Pc) -53.4 NOISE 2 MTI RESIDUE -51.8 AT 15^5 PRF (av.) = 275HzIF BANDWIDTH= 1.6MHz CURVESINGLE-SIDEBAND SPECTRUM 1 STALO(COMBINATION Pc) -53.4 NOISE2 MTI RESIDUE -50.8 AT 1200/is PRF (av.) = 275 Hz IF BANDWIDTH = 1.6 MHzINTEGRATED DOUBLE-SIDEBAND NOISE (dBc) . 
 AP-5, pp. 81–90, 1957.  92. 
 CAV 
 II, pp. 815–818, 2004. 147. 
 RESOLUTION STRIP 
 NETIC FIELD AND PREVAILING SOLAR INDICES 4HESE MODELS REQUIRED SEEDING WITH INITIAL CONDITIONS  OFTEN A LIMITING CONSIDERATION &OR BOTH CLASSES  IMPROVED ACCURACY OF FORECASTING IS ACHIEVED BY ASSIMILATING  DATA FROM GROUND 
 Another useful antenna parameter related to the gain is the effective receiv-  ing aperture, or effective area. It may be regarded as a measure of the effective area presented  226INTRODUCTION TORADAR SYSTEMS directive gaininEq.(7.2),exceptthatthedenominator isthenetpoweraccepted bythe antenna fromtheconnected transmitter~or G=4n(maximum powerradiated/unit solidangle) netpoweraccepted bytheantenna Anequivalent definition is(7.6a) G= maximum radiation intensity fromsubject a~~_enn~________ (b) radiation intensity from(lossless) isotropic sourcewithsamepowerinput 7.6 Thepowergainshouldbeusedintheradarequation sinceitincludes thelossesin­ troduced bytheantenna. Thedirective gain,whichisalwaysgreaterthanthepowergain,isof importance forcoverage, accuracy, orresolution considerations andismorecloselyrelatedto theantenna beamwidth. 
 AMPLITUDE POINT IS NOMINALLY EQUAL TO THE SUBPULSE WIDTH 4HE RANGE RESOLUTION IS HENCE PROPORTIONAL  TO THE TIME DURATION OF  ONE ELEMENT OF THE CODE ONE SUBPULSE  4HE TIME 
 (Translated  from the Russian version published by Moscow: Soviet Radio Publication House, 1962.) ch14.indd   44 12/17/07   2:47:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 
 WlND SPEED (m/s) FIG. 13.7 A hypothetical wind-speed dependence of sea cluttei (curved traces) compared with various power laws (straight lines). (Derived from Pier son and DoneIan.18) WINDSPEED (m/s) FIG. 
 FLYING FIGHTER 
 SHARAD measurements started late 2006 only when  the MRO orbit was circularized after six months of aerobraking. ch18.indd   61 12/19/07   5:15:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
    # # # 
 A BA4A B 
 114. R. K. 
 ,",  
 £Ó°£,iviVÌÀÊÌi>Ã  V >iÊ 
 Large raindrops assume pancakelike shapes as they fall and thus scat- ter back horizontally polarized electric fields more strongly than vertically polarized electric fields. Hailstones, while irregular in shape, appear to tumble while they fall and therefore exhibit no preferred orientation on average. Wind Measurement. 
 Luk (ed.), SPIE Proc. Series vol. 3162  (Conf. 
 Thesesegments mustbeshortenoughtoavoidexcessive delaysinthetransferofcontroltothetime-critical tasks. Thephased-array radaranditscomputer controller saturate differently. Long-range dwellsaredemanding ofradarexecution time,butsincetheygenerally involvealowdatarate theyarenotparticularly demanding ofdataprocessing time.Ontheotherhand,highdatarate trackingofshort-range targetsisnotasdemanding ofradarexecution timeasforlong-range targets.butthedata-processing capability becomes thelim.itingfactor.Thehandling ofalarge numberofshort-range targetsintrackcandrivetheprocessor tofullutilization andrequire thatsearchoperations, whichhavelowerprioritythantrack,bereduced. 
 SOIDAL MODULATIONS 3INUSOIDAL MODULATIONS CAN HAVE A SIGNIFICANT IMPACT ON RADAR  PERFORMANCE  THOUGH THE DEGREE TO WHICH THEY CAUSE DEGRADATION OFTEN DEPENDS ON THEIR RELATIONSHIP TO THE RADAR 02& AND THEIR MAGNITUDE RELATIVE TO THE RANDOM MODU 
 no. 1299, Novem­ ber, 1976.  89. 
 of lowdielectric constant andlowlosstangent inarelatively thick-wall construction tomeet structural requirements withexcellent electrical performance overawidefrequency band.This isknownasa{cwmshellradome. Theindividual panelsmaybejoinedtogether byapplication ofanepoxyadhesive tothepaneledgesorby..welding" together withthesamematerial to formahomogeneous shell.' 05 Thestructural limitation ofthethinwallradomecanbeovercome bythehalFwave wall radome whichutilizes ahomogeneous dielectric withanelectrical thickness ofhalf wavelength. oramultiple thereof,attheappropriate incidence angle.Thehalf-wave thickness isnonref1ecting ifohmiclossesarenegligible. 
 MENT SHARED A COMMON GIMBALED ANTENNA 4HE SCATTEROMETER MEASURED THE NORMALIZED BACKSCATTER COEFFICIENT OF OCEAN AND TERRAIN AS A FUNCTION OF INCIDENCE RANGING FROM n TO n !LTHOUGH ONLY SPARSE COVERAGE OF SELECTED SITES WAS POSSIBLE  THE DATA WERE  SUFFICIENT TO DEMONSTRATE THE POTENTIAL OF SPACE 
 62. A. Farina, G. 
  PREDICTIONS !.&03 
 639-652, May, 1976.  22. Bristol, T. 
 Tileeffectivc bandwidth asdefincd byEq.(r1.16)wasfirstintroduced byGabor4andlias beenusedbyWoodward~ inhistreatment ofdetection andaccuracy bymeansofinverse probability. BothGaborandWoodward definetheeffective bandwidth intermsofthe complex-frequency representation, whilethedefinition presented aboveisintermsofthereal timewaveforms. Inessence, f12isthenormalized secondmoment ofthespectrumISU) 12 aholltthemean(heretakelltobeatzerofrequency). 
 H.  Beyer: V-Beam Antennas for Height Finding, AFCRC-TR-56-115, Air Force Cambridge Nesearch  Center, December. 1956. 
 IEEE T rans. Geosci. Remote Sens. 
 Dig ., 1967. 87. L. 
 TO 
 Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  130          Figure 12.25  Non-linear chirp compressed output us ing Bessel filter, phase -only matched  filter, and 1.5  MHz A/D conversion.   12.2.5  Design Example   When implementing digital filters it becomes possible to compensate for spectral ripples and  thus to improve the resulting pulse compression side lobes. The character istics of such "reci p- rocal ripple" filters [9- 10] are most easily visualized in the frequency domain. 
 Ó{°È{  2!$!2 (!.$"//+   5 .ICKEL  h-ONOPULSE ESTIMATION WITH SUB 
 OE-Il, pp. 158-163, April 1986. 26. 
 15 of" Radar Handbook," M. I. Skolnik (ed.~  McGraw-Hill Book Company, Inc., New York, 1970. 
 Another 10 dB ought to be  allowed to account for variations in the other parameters of the radar equation. Hence the  dynamic range of operation required of the receiver AGC might be of the order of 90 dB, or  perhaps more.  It is found 10 in practice that the maximum gain variation which can be obtained with a  single IF stage is of the order of 40 dB. 
 The selection of  a particular type of receiver front-end might also be influenced by its instantaneous band­ width, tuning range, phase and amplitude stability, and any special requirements for cooling.  The image-recovery mixer represents. a practical compromise which tends to balance its  slightly greater noise figure by its lower cost, greater ruggedness, and greater dynamic range.13  Utility of low-noise front-ends. 
 IEEETrails..vot.AP-18. pr.515-529. July.1970. 
 AGILE SYSTEMS WHOSE RATES ARE TOO FAST TO FOLLOW OR WHEN THE VICTIMS FREQUENCY PARAMETERS ARE IMPRECISELY KNOWN *AMMER SIZE IS CHARACTERIZED BY THE  EFFECTIVE RADIATED POWER %20    ' J0J  WHERE 'J  IS THE TRANSMIT ANTENNA GAIN OF THE JAMMER AND 0J IS THE JAMMER POWER 0ASSIVE %#- IS SYNONYMOUS WITH CHAFF  DECOYS  AND OTHER REFLECTORS THAT REQUIRE NO  PRIME POWER 4HE CHAFF IS MADE OF ELEMENTAL PASSIVE REFLECTORS THAT CAN BE FLOATED OR OTHERWISE SUSPENDED IN THE ATMOSPHERE OR EXOATMOSPHERE FOR THE PURPOSE OF CONFUSING  SCREENING  OR OTHERWISE ADVERSELY AFFECTING THE VICTIM ELECTRONIC SYSTEM %XAMPLES ARE METAL FOILS  METAL 
 G.: The Haystack Microwave Research Facility, Sprctrrrn~, vol. 2, pp. 50 -59, Fchrt~ary,  1965. 
 The Radar Modernization  Project (RAMP) radar system is an L band system built by the Raytheon Company dur - ing the late 1980s to replace the earlier primary and secondary surveillance radars used  for air traffic control by Canada’s Ministry of Transport.35,36 The primary surveillance  radar consists of a rotating reflector, horn-fed by a solid-state transmitter, and interfac - ing with redundant receive channels with receiver-exciters and signal processors. The  primary surveillance radar operates between 1250 and 1350 MHz with a 25-kW peak FIGURE 11.24  AN/SPS-40 transmitter amplifier module ( Photograph courtesy of  Westinghouse Electric Corporation ) ch11.indd   33 12/17/07   2:25:45 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 This custom - ary notation indicates horizontal or vertical (linear) polarizations on both trans - mission and reception for these single-polarized radars. (2)  Dual polarization  The traditional definition is transmission on one polarization  (usually linear, such as H), and reception on the like-polarized and the cross- polarized components (such as H and V). In a traditional dual-polarized radar, the  relative phase between the two polarized data sets is discarded. 
 An offset error of one-hundredth of the PRF would yield 26 dB im- provement for a double canceler with an input clutter spectrum whose width was 3 percent of the PRF. If the radar frequency were 10 GHz, PRF 1 kHz, and ground speed 580 kn, the notch would have to be held within 0.29 kn or 0.005V8. Because of these requirements and the width of the platform-motion spec- trum, stagger PRF systems must be chosen primarily on the basis of maintaining the stopband rather than flattening the passband. 
 The statistical analysis of rainfall in wuhan in the past 50 years. J. Hubei Univ. 
 This loss may vary from I1A to almost 3 dB, depending upon the number of pulses on target. In addition, if quadrature MTI channels (see Sec. 15.12) are not employed, there is an additional loss of I1Xz to 3 dB, again depending upon the number of pulses on target. 
 (ILL "OOK #OMPANY     #HAP   $ + "ARTON  -ODERN 2ADAR 3YSTEM !NALYSIS  .ORWOOD  -ASS !RTECH (OUSE    P   ' -ERRILL  $ * 0OVEJSIL  2 3 2AVEN  AND 0 7ATERMAN   !IRBORNE 2ADAR  "OSTON "OSTON  4ECHNICAL 0UBLISHERS    PP n  $ $ (OWARD  h2ADAR TARGET ANGULAR SCINTILLATION IN TRACKING AND GUIDANCE SYSTEMS BASED ON  ECHO SIGNAL PHASE FRONT DISTORTION v IN 0ROC .AT %LECTRON #ONF  VOL   /CTOBER   2 ( $ELANO  h! THEORY OF TARGET GLINT OR ANGLE SCINTILLATION IN RADAR TRACKING v  0ROC )2%  VOL    PP n  $ECEMBER   2 ( $ELANO AND ) 0FEFFER  h4HE EFFECTS OF !'# ON RADAR TRACKING NOISE v  0ROC )2%  VOL     PP n  *UNE   * ( $UNN AND $ $ (OWARD  h4HE EFFECTS OF AUTOMATIC GAIN CONTROL PERFORMANCE ON THE TRACK 
 L. J. Cutrona, W. 
 JT-10, pp. 152-159, April, 1964.  4. 
 W IDEBAND 
 PULSE WIDTH VERSUS PEAK TIME SIDELOBE LEVEL  C  3.2 LOSS  VERSUS PEAK TIME SIDELOBE LEVEL . n°£ä  2!$!2 (!.$"//+  3!7 $EVICES FOR ,&- 0ULSE #OMPRESSION  ! 3URFACE !COUSTIC 7AVE 3!7   DEVICE CONSISTS OF AN INPUT TRANSDUCER AND AN OUTPUT TRANSDUCER MOUNTED ON A PIEZO 
 POWER  BEAMWIDTH MAY BE USED AS AN APPROXIMATION  RESULTING IN THE BANDWIDTH GIVEN BY  %Q  %FFECT OF $ETECTION  4HE EFFECT OF DETECTING NARROWBAND NOISE HAS BEEN TREATED  EXTENSIVELY IN THE LITERATURE (ERE  IT IS NECESSARY ONLY TO SHOW THE POSTDETECTION SPECTRUM OF THE PRECEDING EXAMPLE AND TO CONSIDER THE NUMBER OF INDEPENDENTLY FADING SAMPLES PER SECOND &IGURE  SHOWS THE SPECTRUM BEFORE AND AFTER SQUARE 
 B-scope. An intensity-modulated rectangular display with azimuth angle indicated by the horizontal  coordinate and range by the vertical coordinate.  C-scope. 
 Adifferent approach totheproblem isline-oj-sight, ortilt,stabilization. Insteadofmount­ ingtheantenna onalevelplatform, theantenna istiltedabouttheelevation axissoas toautomatically maintain thebeampointedatthehorizontal. (Thebeamdirection canalsobe maintained constant atwhatever angleaboveorbelowthehorizon isdesired.) Thelineofsight istherebystabilized. 
 It was particularly important that the radars were operated at peak ef ﬁciency, and that losses in sensitivity due to poor maintenance or tuning were minimised. Thisproblem was further addressed in TRE Report T1863 [ 11], describing trials under- taken in March 1945 with ASV Mk. VI and VIA in Wellington aircraft of Coastal Command. 
 Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft.  MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 The subsuite of multi-target track (MTT) contains conventional track while scan  (TWS), passive tracking of emitters or echoes from bistatic illumination, missile track - ing with or without a missile datalink or beacon, and several modes to recognize  target number and type: raid assessment and noncooperative target recognition (usu - ally incorrectly called target identification ). The fighter and wingman will coordinate  modes through the net so that both have situational awareness during the long time  span required to provide target recognition. 
  
 Since aluminum alloy has better forming characteristics than magnesium, itisconsidered thebest material forthereflector face. The most accurate method offorming aluminum alloy sheet forthereflector face isbystretching the material over ametal diewhich has been cast and ground tothe desired contour; these dies are usually made from Kirksite, alead and zinc alloy. After forming, thesheet metal conforms totheexact contour ofthedieproviding thedraw isshallow enough, asis thecase with most radar reflectors. 
 The controller desires toknow the position ofagiven signal with respect toamap orgrid—which must therefore besomehow super- posed on the display—and hc wishes torecord the position ofa target onsuccessive sweeps, todetermine thedirection and approximate speed ofitsmotion. Optical Superposition. —Optical devices ofthe same general character asthe chart projector mentioned inthelast section arehelpful forthese purposes. 
 The most common expression is the relative sidelobe level, defined as the peak level of the highest sidelobe relative to the peak level of the main beam. For example, a " — 30 dB sidelobe level" means that the peak of the highest sidelobe has an intensity (radiated power density) one one-thousandth (10 ~3 or -30 dB) that of the peak of the main beam. Sidelobe levels can also be quantified in terms of their absolute level relative to isotropic. 
 NORMAL CLUTTER v IN  )%%% )NT 2ADAR #ONF   7ASHINGTON   $#    PP n  h2ADAR PROCESSING SUBSYSTEM EVALUATION v VOL   *OHNS (OPKINS 5NIVERSITY  !PPL 0HYS ,AB  2EPT &0 
 Sherman: Dynamic Programming Applied to Unequally  Spaced Arrays, IEEE Tram.., vol. AP-12, pp. 35-43, January, 1964. 
 itisassumed thatrain.snow.hail.orotherhydrometeors mayberepresented asalargenumber ofindependent scatterers ofcrosssection (i/locatedwithintheradarresolution cell.LetL(ij denotetheaverage totalbackscatter crosssectionoftheparticles perunitofvolume. The indicated summation offTjiscarriedoutovertheunitvolume. Theradarcrosssectionmaybe expressed as(i=limL(ij.whereVmisthevolumeoftheradarresolution cell.Thevolume Vm occupied byaradarbeamofvertical beamwidth 1JB'horizontal beamwidth 0B'andapulse ofduration risapproximately (13.15) wherec=velocityofpropagation. 
 Surface wind speed and significant wave  height63 are derived from the AGC values and the waveform’s shape, respectively. The precision of an individual height measurement is determined by the combination  of range resolution and incoherent waveform averaging. If a single simple short pulse  were transmitted, then the height resolution would equal the pulse length. 
 BEAM CLUTTER SPECTRAL WIDTH  $F DUE TO PLATFORM MOTION MEASURED  D" DOWN FROM THE PEAK IS APPROXIMATELY   $F62 ""       LQF QQF QCOS  SIN  COS  COS  C C HTF Q FSIN   COS   COS    ª « ¬¹ º »   . 
 LAR PIXEL OF A COMPLEX IMAGE OF COMPLICATED TERRAIN  SUCH AS VEGETATION "Y hPIXELv WE MEAN THE COMPLEX NUMBERMAGNITUDE AND PHASETHAT  AFTER 3!2 PROCESSING  CORRESPONDS TO A PARTICULAR LOCATION ON THE GROUND  )F ONLY ONE SCATTERER WERE IN THE REGION OF GROUND REPRESENTED BY THE PIXEL  THEN THE PIXEL MAGNITUDE AND PHASE WOULD BE A FUNCTION OF THE SCATTERERS EXACT POSITION 3INCE THE REGION REPRESENTED BY THE PIXEL TYPICALLY CONTAINS MANY SCATTERERS  THE COMPLEX PIXEL VALUE IS THE SUM OF THE &)'52%   #OMPARISON OF 3!2 AND OPTICAL IMAGERY /PTICAL IMAGERY IS BASED ON  AN hANGLE 
 Optical processing has proved to be well suited to the needs of SAR, except that it is seldom  done in real time. The radar output is usually stored photographically and processed later on  the ground.  In optical processing, the electrical signals at the radar output are converted to optical  images on film. 
 IEEE T rans. Geosci. Remote Sens. 
 Their effect on the civilian popu - lation is disastrous and major efforts are being made by the international community  to clear the problem. Most detection is done with metal detectors, which respond to  the large amount of metallic debris in abandoned battlefield areas and hence have  difficulty in detecting the minimum metal or plastic mine. GPR technology is being  applied to this problem as a means of reducing the false alarm rate and providing  improved detection of low-metal-content mines. 
 Sensors 2019 ,19,6 3 of our method in ship classiﬁcation, the point of ship classiﬁcation is that we cannot get enough high-resolution SAR ship images. Therefore, if we can solve the data problem, we think we can also get good results when promoting our method to other SAR ﬁelds with more images and details. Other procedures in the preprocessing step of the images, such as images with GAN, SRCNN, may be the focus of future work. 
 WAY  POWER PATTERN OF INTEREST WITH THE GAUSSIAN APPROXIMATION AT A SPECIFIC POINT ON THE PAT 
 65 69. March. 1979. 
 Smith, R. A.: "Aerials for Metre and Decimetre Wave-Lengths," Cambridge University Press.  London. 
 and N. P. Robinson: Polarization of Radar Echoes, Including Aircrart. 
 RESOLUTION DOPPLER SYSTEM CAN RESOLVE MAJOR REFLECTORS AND LOCATE THEM IN CROSS RANGE AS A FUNCTION OF THE DOPPLER DIFFERENCE FROM THE REFERENCE REFLECTOR 4HIS TECHNIQUE  CALLED  INVERSE SYNTHETIC APERTURE RADAR )3!2    USES THE TARGET  MOTION FOR THE NEEDED ASPECT CHANGE  INSTEAD OF RADAR MOTION AS USED IN CONVENTIONAL SYNTHETIC APERTURE RADAR  TO OBTAIN DETAILED CROSS 
 22.9 Global coverage by polar orbits.28ALL ORBITS ARE ClRCULAR, POLAR, ORDEREDHORIZON-LIMITED VIEWING NO. OFORBITPLANES-VEHICLESEQUALLY DISTRIBUTEDNUMBER OF VEHICLES VEHICLESREQUIRED HIGHESTLATITUDE COVERED HORIZON-LIMITED VIEWINGS\WATHWIDTH, nm . ORBITAL HEIGHT (nm) FIG. 
 Figure 99 isaphotograph ofthe PPI display, showing the performance ofthis antenna.. SEC. 9.3] FANBEAMS 275 The cosecant-squared fan beam isused not only inairborne naviga- tional radar but also insurface-based radar forthedetection ofairplanes, Inthis case thefanisinverted, theintention being that atarget airplane FIci. 
 γis the chirp rate. The echoed signal reﬂected from a point target can be expressed as: s(τ,t)=σ·rect⎛ ⎜⎜⎜⎜⎜⎜⎝τ−2R(t) c Tp⎞ ⎟⎟⎟⎟⎟⎟⎠exp⎧⎪⎪⎨⎪⎪⎩j2π⎡ ⎢⎢⎢⎢⎣f c⎭parenleftBigg τ−2R(t) c⎭parenrightBigg +γ 2⎭parenleftBigg τ−2R(t) c⎭parenrightBigg2⎤ ⎥⎥⎥⎥⎦⎫⎪⎪⎬⎪⎪⎭(2) where tdenotes the slow time, R(t) is the instantaneous slant range history from the radar to the point target at time t.σis the radar cross-section (RCS) of the target, and cis the velocity of light. According to the DBS geometry illustrated in Figure 1, the instantaneous slant range history between the target and the radar can be written as: R(t)=⎭radicalBig R2 0+(vt)2−2R0vtsinθcosϕ (3) Equation (3) can be expanded into a Taylor series, and it can be expressed as: R(t)=R0−vtsinθcosϕ+(vt)2⎭parenleftBig 1−sin2θcos2ϕ⎭parenrightBig 2R0+O⎭parenleftBig t3⎭parenrightBig (4) Since the dwell time in each ﬁxed azimuth viewing angle is very short, the value of the airplane travels vtis far less the slant range R0(i.e., vt/squareR0), then the instantaneous slant range history can be approximately expressed as: R(t)≈R0−vtsinθcosϕ (5) The Doppler centroid can be estimated by the follows: fd=−2 λdR(t) dt=2vsinθcosϕ λ(6) It can be known that di ﬀerent azimuth angles corresponds to di ﬀerent Doppler frequencies. 
 The quantities Kland K2are constants, but Ksmay depend somewhat onAand f,. For example, itis probably harder tostabilize the local oscillator at3cmthan at10cm. Again, Eq. 
 AES-7, pp 269-278,  March, 1971.  59. Hoft, D. 
 BEAM NOISE JAMMING ALSO APPLY TO SIDELOBE  NOISE JAMMING  WITH THE ADDITION THAT THE SIDELOBE RESPONSE IN THE DIRECTION OF THE JAMMER MUST BE MINIMIZED 5LTRALOW SIDELOBES IN THE ORDER OF  SAY   D" BELOW THE ANTENNAS MAIN 
 ERING SUCH ISSUES AS AZIMUTH SHIFT  RANGE WALK  AND AZIMUTH DEFOCUS h0ROBABLY THE WORST DEFECTWILL BE DISPLACEMENT OF MOVING TARGETS IN THE AZIMUTH DIRECTION  AWAY FROM THEIR TRUE POSITION ON THE GROUND 4HE PREFILTER WE HAVE DESCRIBED IS OPTIMISED FOR TARGETS TRAVELING RADIALLY3UCH TARGETS WILL APPEAR AT THEIR CORRECT POSITION IN THE -4) IMAGEv )NTERFEROMETRIC  3!2  )N3!2   FOR  -OVING  4ARGET  )NDICATION  -4)   !S  MENTIONED IN 3ECTION   )NTERFEROMETRIC 3!2 )N3!2  SOMETIMES ALSO CALLED  )&3!2  REFERS TO THE USE OF TWO ANTENNAS WHOSE SIGNALS ARE COMBINED COHERENTLY 4HE TWO ANTENNAS ARE DISPLACED HORIZONTALLY ALONG A LINE PARALLEL TO THE GROUND  TO DETECT AND ANALYZE MOVING TARGETS AND ARE DISPLACED VERTICALLY TO ESTIMATE  TERRAIN HEIGHT "OTH TYPES OF )N3!2 ARE DISCUSSED HEREIN 4HE FORMER IS DISCUSSED IN THIS SECTION AND THE LATTER IS DISCUSSED LATER IN h)NTERFEROMETRIC 3!2 )N3!2  FOR 4ARGET (EIGHT -EASUREMENTv )N3!2 TO DETECT MOVING TARGETS WAS ORIGINALLY DEVELOPED BY THE *ET 0ROPULSION  ,ABORATORY *0,  TO DETECT OCEAN CURRENTS    AND HAS BEEN IMPROVED BY SEVERAL  AUTHORS /NE OF THE MOST SOPHISTICATED TECHNIQUES HAS BEEN DEVELOPED FOR THE  *OINT 34!23 AIRCRAFT AND USES AN INTERESTING COMBINATION OF 3!2 AND -4) TECH 
 #HEBYSHEV FILTER BANK  ,M    D"  &OR THE REMAINING FILTERS  A RELATIVE SPAC 
 VATED BY THE NEED TO SUPPRESS DIRECTIONAL AMBIGUITIES  WITHIN THE CONSTRAINT OF A PHYSI 
 ENT PROCESSING INTERVAL IS SEGMENTED  AS SHOWN IN THE BOTTOM ROW OF &IGURE  4HE PARTICULAR EXAMPLE SHOWN IS TRACKING THAT MIGHT BE USED IN &44  '-44  065  OR ! 
 In these environments, the radar has to detect targets that can have  echoing areas ranging from less than one square meter to many tens of thousands of  square meters; important targets can have relative speeds ranging from stationary to  100 knots or more; the targets can be situated in extreme precipitation and sea clutter  conditions; and the radar antenna is not mounted on a static nor a stable platform. The  radar is used to prevent collisions and groundings at sea and is, therefore, an important  safety related system, requiring integrity and reliability. For most commercial ships,  the radar needs to meet stringent, internationally agreed performance criteria. 
 PLE  THE ROLE PLAYED BY THE SCHEDULER IN A MULTIFUNCTIONAL 0!2 TO COMBAT %#- 4O THIS END  WE RESORT TO A BENCHMARK STUDY DESCRIBED IN THE LITERATURE  WHICH DEFINES TYPICAL %#- THREATS  OPERATIONAL SCENARIOS  AND PHASED 
 Since the reflected beam does not scan, it should be possible to provide a good match at the input aperture. Matching the input aperture, in this case, is equivalent to providing the radiating aperture with independent feeds. Any secondary reflection from the input aperture will radiate in the original direction of scan. 
 ING FOR THE ADAPTIVE WEIGHT ESTIMATE YIELDS THE DESIRED CONDITION FOR OPTIMAL ADAPTIVE WEIGHTING  E 
 63. Dietz, R. H.: Space Station Communications and Tracking Systems, Proc. 
 Mean- while, thetransmitted pulse train isdecoded and passed through switch c,whose purpose istoexclude the basic pulse and the modulator pulse. The two pulse trains are brought together ina“comparison” circuit which produces apolarized error voltage ifthey donotcoincide. (Ifthe two pulse trains have slightly different frequencies, because ofslight differences intheoscillators, theerror voltage will refer totheir “centers ofgravity.”) The amplified error voltage controls amotor which turns thephase shifter insuch away that theerror voltage iskept very small,’ and the phase shifter and the data transmitter rotate insynchronism with the radar scanner. 
 The width of this region is very specific to the particular prob - lem. When gtrack is large and very little delay in the output can be tolerated, then the  region of applicability is fairly small and very simple multiple hypothesis approaches  (splitting tracks into at most one or two hypotheses) are then the best answer . When gtrack is small, then PDA/JPDA can be used to operate at significantly higher  false alarm densities. 
 Appl. Earth Observ. Remote Sens. 
 The contact isusually made byarnicroswitch operated byacamon arotating shaft. Since itisimpossible toopen and close theswitchin ashort enough angular interval, unless thescan isvery slow, some device forproducing ashort pulse must be introduced. This can consist ofaflip-flop triggered bythemicro- switch although, formedium orslow scam, itispossible tomake useofthetransit time, ofamechanical relay.1 Inorder toproduce asetofmarkers, anequal numbeqof cams ona one-speed shaft or Rotatingdisk 6CP+25Gv Light bulb 6,3v * FIG.13.33 .—Photocel1 index circuit. 
 TIVE TO A LOCAL VERTICAL AT THE %ARTHS MEAN OBLATE SPHEROIDAL SURFACE  &)'52%   /VERVIEW OF 0!,3!2S VIEWING GEOMETRIES %ACH OF THESE BEAM POSITIONS SUPPORTS A  VARIETY OF POLARIZATION COMBINATIONS  LEADING TO A VERY LARGE NUMBER OF AVAILABLE MODES 4HE SOLAR PANEL  IS ORTHOGONAL TO THE ORBIT PLANE  INDICATIVE OF A MIDDAY SUN 
 The complete pulser, including pressurized housing and cooling system, weighs around 300 lb.. CHAPTER 11 R-F COMPONENTS BY A.E.WHITFORD 11.1. The R-f Transmission Problem.—In the block diagram ofa basic radar system shown inFig. 
 D., and A. E. Ruvin: Recent Advances in the Synthesis of Comb Filters, IRE Natl. 
 The phase shifter is set so that the Q, or quadrature, detector receives signals in phase quadrature* and, to first order, is sensitive only to FM. Should there be a requirement for AM stabilization, it would normally be only at very low fre- quencies such as those introduced by the power supplies. Such a requirement could be met easily by adding a ir/2 phase shift and an / (coherent amplitude- sensitive) detector, as indicated by the dotted blocks in Fig. 
  During reception the duplexer lead the weakly echo signals to the receiver.    The hypersensitive receiver amplifies and demodulates the received RF -signals. The  receiver provides video signals on the output. 
 Remote Sens. 2018 ,12, 025011. [ CrossRef ] 26. 
 Procedures for the synthetic shorten ing of the pulse duration have already been dealt  with through digital and analog pulse compression and are used in practice.  With this pulse  times after compression of 1 ns or smaller can be achieved, meaning that the resolution ∆R  amounts to around 15 c m.  At the receiver and/or with signal processing there must then be an  available bandwidth of >1 GHz. 
 104. S. P. 
 BAND MEASUREMENTS    3UMMING THESE  COMPONENTS YIELDS THE VIRTUAL DOPPLER VELOCITY AT THE PEAK OF THE CLUTTER SPECTRUM FOR  THE PARTICULAR CASE OF A  VERTICALLY POLARIZED 8 
 LATE AND CONTAMINATION OF THE SURFACE WAVE RETURN WITH ECHOES RECEIVED VIA SKYWAVE PATHS WILL BECOME INCREASINGLY SEVERE  SO QUANTITATIVE PERFORMANCE PREDICTIONS AT LONG RANGES  BEYOND ^ KM  SHOULD BE TREATED WITH CAUTION , 
 The angular estimate that is obtained by either taking the maximum value of the running sum or taking the midpoint between the first and last crossings of the detection threshold has a bias of nil pulses, which is easily corrected. The standard deviation of the estimation error of both estimators is about 20 percent higher than the optimal estimate specified by Cramer-Rao bound. A disadvantage of this detector is that it is sus- ceptible to interference; that is, one large sample from interference can cause a detection. 
 The batch processor, like the binary integrator, is easily implemented, ignores interference spikes, and works extremely well when the noise has a non-Rayleigh OPTIMUM Pn . S/N (dB) FIG. 8.9 Comparison of binary integrator (M out of AO with other integration methods (Pfa = 10~10; PD = 0.5). 
 Sensors 2019 ,19, 516 Joining Equations (7)–(8) leads to 0.66 Nemax TEC To p (NmF2)2=HT/parenleftbigg exp/parenleftbigg 1−e−Hs−hmF2 HT/parenrightbigg −1/parenrightbigg (9) Solving the nonlinear Equation (9), we can obtain HT. Thus, the topside proﬁle can be obtained from Equation (3) with the TEC-related constant scale height HT. 3. 
 Finally, the trials reported anincreased sensitivity to interference from rain clouds but these returns could be distinguished due to their ‘vagueness ’. There was some concern that the presence of rain might make coast recognition more dif ﬁcult at X-band. Following the introduction of the schnorkel in U-boats during 1944, there was renewed interest in the use of X-band for ASV [ 2]. 
 An alternative mechanization  is to replace the range-varying STC with an equivalent RCS threshold inside the  range correlation process. The RCS is computed for each possible unfolded range  (starting from the shortest range) and compared to the RCS threshold. Detections  that range correlate, but are below the RCS threshold, are prevented from cor - relating with other detects (and all of their unfolded ranges are also prevented   from correlating). 
 Paige: Surface-Acoustic-Wave Devices for Signal Processing Applications,  Proc. IEEE, vol. 64, pp. 
 D. K. Barton and H. 
 DESIGNED SYSTEM  BY THE )&  o  !LL SIGNAL PROCESSING FOLLOWING THE  !$ DETECTOR IS DONE DIGI TALLY )T IS MORE MEANINGFUL  HOWEVER  TO DESCRIBE AND  DEPICT THE PROCESSING IN AN ANALOG MANNER p  4HE )& BANDPASS LIMITER ; 2ADAR (ANDBOOK  ND %D   PP n= SHOWN IN THIS  AND SUBSEQUENT DIAGRAMS HAS AN  AMPLITUDE OUTPUT CHARACTERISTIC THAT IS LINEAR FOR INPUT SIGNAL VOLTAGES FROM NOISE LEVEL TO WITHIN  D" OF THE LIMITER  OUTPUT MAXIMUM VOLTAGE AND  THEN TRANSITIONS SMOOTHLY TO THE MAXIMUM OUTPUT VOLTAGE 4HE PHASE OF THE INPUT  SIGNAL IS PRECISELY PRESERVED 4HESE LIMITER CHARACTERISTICS EXIST WHETHER THE FILTER IS IMPLEMENTED IN ANALOG CIRCUITRY OR A DIGITAL ALGORITHM. Ó°ÇÈ  2!$!2 (!.$"//+  BANDPASS LIMITER THAT PRECEDES THE !$ CONVERTER )F SYSTEM INSTABILITIES CANNOT BE CON 
 Skolnik (ed.), McGraw­ Hill Book Company, New York, 1970.  48. Ko, H. 
 DELAY  CIRCUITS 3ECTION   ARE NORMALLY TOO CUMBERSOME TO BE ADDED TO EACH RADIATING ELE 
 RADAR-77, pp. 115-1 19, Oct. 25-28, 1977, IEE (London) Conference Publication no. 
 Atkins, “Nonlinear frequency modulation chirps for active sonar,” IEE Proc.- Radar, Sonar Navig ., vol. 146, no. 6, pp. 
 Thisincrease inthethreshold isequivalent toaloss. Operator loss.Analert,motivated, andwell-trained operator shouldperform aswellas described bytheory. However, whendistracted, tired,overloaded, ornotproperly trained, operator performance willdecrease. 
 HF OVER-THE-HORIZON RADAR  20.816x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 103. M. A. 
 C. Young of tile Naval Research Laboratory  detected a wooden ship using a CW wave-interference radar with separated receiver and  transmitter. The wavelerlgth was 5 m. 
 SPACE PROPAGATION MODEL IS USUALLY INADEQUATE  FOR PROPAGATION ASSESSMENT APPLICATIONS  AND OTHER PROPAGATION  MECHANISMS NEED CON 
 Only areasonable degree oflinearity isrequired; theresponse slope should not vary bymore than perhaps 15per cent. The real difficulty arises from the proximity ofthe carrier and video frequencies and from the requirement that the delayed and undelayed video signals must cancel to1per cent inamplitude. Insimple modulators, modulation components are removed from the modulated carrier channel by frequency discrimination. 
 This is an example of a parallel-series feed. It may be considered as a  number of frequency-scanned linear arrays placed side by side.  When the power splitters are four-port hybrid junctions, or the equivalent, the feed is said  to be matched. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 intersite separation is about 50–100 nautical miles, much less than the range to the  target zone but sufficient to prevent self-jamming when using continuous waveforms  and to separate the transmit and receive range ambiguity zones in azimuth. 
 FUNCTION  RADAR v #HAPTER  IN  !PPLICATIONS OF 3PACE 
 Croney, J., and A. Woroncow: Dependence of Sea Clutter Decorrelation Improvements Upon Wave  Height, I EE JIit. Cm1fonAdt•ances in Marine Navigational.Aids, July 25-27, 1972, IEE (London)  Conference Publication no. 
 15.30 Average SCR improvement for the 68 dB Chebyshev filter bank shown in Fig. 15.28. CPI = nine pulses. 
 All the measurements described  above were made at microwave frequencies between UHF (428 MHz) and Ka band  (35 GHz). High-frequency (HF) radars usually operate in the frequency range  between about 5 and 30 MHz, corresponding to wavelengths between 60 and 10 m,  respectively. Since the operation of such radars takes place either by the ground  wave or over ionospheric ( sky-wave ) paths spanning great ranges, the grazing angles  tend to be small (between 0° and 20°). 
 Whitmer: "Crystal Rectifiers," MIT Radiation Laboratory Series, vol. 15,  McGraw-Hill Book Company, New York, 1948.  6. 
 The absolute level of additive noise sources is  determined by the source and its relation to the radar. Proper system design can reduce  thermal noise to a level where multiplicative noise can become significant in limiting  the radar sensitivity. Multiplicative noise is characterized by either a time-varying amplitude (ampli - tude modulation, AM) or a time-varying phase (phase modulation, PM, or frequency  modulation, FM). 
 visible at speeds less the 3.5 wavelengths per interpulse period. The performance at other angles is between these two cases, and peaking does not occur. 16.9 LIMITA TION OF IMPROVEMENT FACTOR DUE TO PULSE ENVELOPE SHIFT The doppler frequency that arises because of the radial component of aircraft mo- tion results in an incremental phase shift between successive radar pulses. 
 The ground stations send out their pulses, these trigger  off the airborne set, and new pulses come back home to  the ‘cat’ and ‘mouse’ receivers. The total time for each  of these transmissions is made up of a number of com-  plicated parts—for instance, there is the time of outward  travel, time delay in triggering off the mobile equipment,  and time of the return to the ground station. The time  of the second journey must be known accurately, for this  gives the range of the aircraft from the fixed station. 
 The VTS antenna is mounted on a static platform.  This means that the vertical pattern can be more optimally shaped. Also, since the  design does not have to cope with the shock, vibration and instability experienced on  ships’ radar masts, larger antennas become feasible. 
 ING A NEAR 
 Itisadvantageous touse abias slightly beyond cutoff inalate amplifying stage inorder tosuppress any spurious low-level oscillations which, bytheir persistence, might introduce anappreciable phase error either before orafter locking. The actual injection ofthe locking pulse into theoscillator might beaccomplished inany ofseveral ways, including the use ofanextra oscillator control grid. The most flexible method and theonemost widely used istheconnection oftheplate ofapent ode injection-tube across all, orpart of,the LC-circuit ofthe oscillator. 
 £n°Çä  2!$!2 (!.$"//+   # 7U  9 ,IU  + ( +ELLOGG  + 3 0AK  AND 2 , 'LENISTER  h$ESIGN AND CALIBRATION OF THE  3EA7INDS SCATTEROMETER v  )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS   VOL    PP n    - 7 3PENCER  # 7U  AND $ ' ,ONG  h)MPROVED RESOLUTION BACKSCATTER MEASUREMENTS WITH THE  3EA7INDS PENCIL 
 TO 
 83. W. Rotman and R. 
 Alternatively adjustable RF attenuation may be used.  Either form provides increased dynamic range above that provided by the analog- to-digital (A/D) converters. RF attenuation is described in more detail in Section 6.6. 
 NOISE 
 630-637, December 1986. 82. Retzer, G.: Some Basic Comments on Multistatic Radar Concepts and Techniques, IEE Colloq. 
 I11 tlie Fraurillofer region, the integral for electric field intensity in terms of current  distributioti across the aperture is given by a Fourier transform. Consider the rectangular  aperture and coordiriate system shown in Fig. 7.2. 
 Examples are  jet engine or propeller modulation returns associated with aircraft tar gets. ARMs pose a serious threat to a surveillance radar. The survivability of a surveil - lance radar to an ARM attack relies upon waveform coding (to dilute the energy in the  frequency range), the management of radiated energy in time and along the angular  sectors, and the adoption of low sidelobes in transmission. 
 Itisclear that wehave todowith two entirely independent processes, each ofwhich consists simply ofone-way transmission and reception. Consider thefirst process, usually called “interrogation.” LetP,bethe power transmitted bythe radar, ~bthe signal power received bythe beacon antenna. These must berelated by ()A%=p, =) (14) where G,and Gbarethe gains ofthe radar and beacon antennas respec- tively. 
 CLUTTER RATIO AT THE INPUT OF THE CLUTTER FILTER  AVERAGED UNIFORMLY OVER ALL TARGET RADIAL VELOCITIES OF INTEREST 4HE -4) IMPROVEMENT FACTOR LIMITATION DUE TO THE 34!,/ MAY BE EXPRESSED AS THE RATIO OF THE 34!,/ POWER TO THE TOTAL INTEGRATED POWER OF THE RETURN MODULATION SPECTRUM IT CREATES AT THE OUTPUT OF THE -4) FILTERS &IGURE  ILLUSTRATES THE EFFECT OF THE OVERALL FILTERING  CONSISTING OF -4) FILTERING AND RECEIVER FILTERING ON THE RESIDUE POWER SPECTRUM 4HE INTEGRATED RESIDUE POWER DUE TO THE 34!-/ PHASE NOISE IS GIVEN BY   0( F , F D F RESIDUE  ` 
 TO 
   LOBES ^ D"   RANGE AMBIGUITIES EVERY  KM  AND MODEST RANGE RESOLUTION ^ KM   AND CONCLUDED THAT SUCH WAVEFORMS WERE MORE SUITABLE FOR DOPPLER MEASUREMENTS 4HIS FINDING ESTABLISHED THE PRECEDENCE FOR SUBSEQUENT 0"2 DEVELOPMENTS DOPPLER EXPLOITATION OF STABLE  NARROW 
 [)R.:Diathermy VersustheMicrowaves andOtherRadio-frequency Radiations: ARoseby Another NameisaCabbage. RadioSciellce, vol.12.pp.355364, May--June. 1977. 
 E.. and C. E. 
 [ CrossRef ] 40. Chen, B.B.; Gong, H.L.; Lei, K.C.; Li, J.W.; Zhou, C.F.; Gao, M.L.; Guan, H.L.; Lv, W. Land subsidence lagging quantiﬁcation in the main exploration aquifer layers in Beijing plain, China. 
 M.: A Moving-Window Detector for Binary Integration, IEEE Trans., voi. IT-13, pp. 2-6,  January. 
 Ingeneral, the three bridges appear asequally strong signals; inthe particular sweep corresponding tothis photograph the third bridge returned apoor signal. Many structures stand out against ground return because they project vertically above the surrounding level ground and intercept energy intcmlcd fortarget areas behind them. The central portion of therailroad inFig. 
 ORDER TERMS GIVES AN IMPROVED CORRECTION SIGNAL. 
 Althougli kriowledge of sea clutter is far from complete, it is better understood than is  tlie kriowledge of land clutter.  Information about the radar backscatter from land is required for several different appli-  cations, eacli of which has its own special needs. These applications include:  C  Thc dt'tec'tiorr of'nir.crcifi or1c7r. 
 50-52, March, 1958.  45. Hansen, V. 
 This indicates how the  radar output can be made to measure rainfall.  The backscatter cross section per unit volume as a function of wavelength and rainfall . ~,  !'  "E 101 ,,  C ::,  :ii io-2  Q  C  0  ~ 10·3  V)  "' <" 0  b 10-4  L  Cl) --CJ  v-; 10-5 .x u  CJ rn  w-1  0.1 /  ..,.,-::  I 10  r, rainfall role. 
 Severalotheranalytical probability densityfunctions that liebetween thesetwoextremes havebeensuggested formodeling theactualstatistical. 480 INTRODUCTION TO RADAR SYSTEMS  variations received from clutter. One of these is the contan~inateti-norrnal pdf which consists  of the sum of two gaussian pdfs of different standard deviations and different relative  weightings.12 This pdf can be fitted to the data of Fig. 
 White, W. D.: Double Null Technique for Low Angle Tracking, Microwave J., vol. 19, pp. 
 R. Eames, and K. A. 
 SENSING DIFFERENCE SIGNALS 4HERE ARE MANY TRADEOFFS IN FEED DESIGN BECAUSE OPTIMUM SUM AND DIFFERENCE SIGNALS  LOW SIDELOBE LEVELS  SELECTABLE POLARIZATION CAPABILITY  AND SIMPLICITY CANNOT ALL BE FULLY SATISFIED  SIMULTANEOUSLY 4HE TERM  SIMPLICITY REFERS NOT ONLY TO COST SAVINGS BUT ALSO TO THE USE  OF NONCOMPLEX CIRCUITRY  WHICH IS NECESSARY TO PROVIDE A BROADBAND SYSTEM WITH GOOD  BORESIGHT STABILITY TO MEET PRECISION 
 Roy.Meteor.Soc.,vol.80,pp.522-545, October, 1954. 72.Haddock, F.T.:Scattering andAttenuation ofMicrowave Radiation Through Rain.Nat'alResearch Lahoratory, Washington, D.C.(unpublished manuscript), 1948. 73.Smith,P.L.,Jr.,K.R.Hardy,andK.M.Glover: Applications ofRadartoMeteorological Opera­ tionsandResearch, Proc.IEEE,vol.62,pp.724-745. 
 PHYSICS RETRIEVAL USING 3 
 The doppler beat frequency j~ between the scattered and direct signals in the bistatic radar  is proportional to the time rate of change of the total path length of the scattered signal.  fd = 11:l (D, + Dr) I (14.34)  where A is the wavelength of the transmitted signal. The doppler frequency shift provides a  means for discriminating stationary objects from moving targets, but it is not a measure of the  radial velocity as with the monostatic radar. 
 24. W. P. 
 Examples of dispersive antennas that  have been used in ultrawideband radar are the exponential spiral, the Archimedean  FIGURE 21.17  Radiated field pattern from a conducting dipole element due  to an applied impulse ( Courtesy IEE ) ch21.indd   25 12/17/07   2:51:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 
 Changes in ampli- tude cause errors since the sequential measurements are necessarily made at different instants . OTHER RADAR TOPIC'S 545  or time. This is similar to the effect or amplitude fluctuations on tracking radar, as discussed in  Sec. 
 In military systems, high range resolution may be employed for counting the  number of aircraft flying in close formation and for recognizing and thwarting some  types of deception countermeasures. Tunable bandwidth offers the ability to change (tune) the radar signal frequency  over a wide range of the available spectrum. This can be used for reducing mutual inter - ference among radars that operate in the same frequency band, as well as in attempting  to make hostile electronic countermeasures less effective. 
  
 MERCIAL VESSELS HAD AN IMPORTANT PART TO PLAY IN ANTI 
                &)'52%   6ARIATION OF THE PEAK BACKSCATTER COEFFICIENT AS A FUNCTION OF WIND DIRECTION RELATIVE TO THE  RADAR LOOK DIRECTION FOR VARIOUS SPREADING FUNCTIONS  ASSUMING A SEA FULLY DEVELOPED AT THE "RAGG 
 308 ANTENNAS, SCANNERS, AND STABILIZATION [SEC. 917 isamisalignment between thebeam axis and horizontal, thesynchros in thegyro-torque unit transmit theerror totheamplifier, aphase-sensitive detector whose output controls theservomotor, which inturn causes the linkage system totilttheantenna upordown until thebeam axis isagain horizontal. Because the gyro ismounted onthe scanner, itisliable to the precession caused bythe inertia ofthe supporting gimbal system. 
 and western Canada. ch16.indd   52 12/19/07   4:56:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 1 DEMODULATION  MATCHED FILTERING  AND SYMBOL 
 Since the RF pulse propagates  at the speed of light, the time it  takes the echo to return is  proportional to the distance from the target. This, of course,  applies to a primary -radar, one that relies on reflected energy  bouncing back off the target. Secondary -radars , that re - transmit the signal back from a transponder , have additional  delays. 
 EST PROPORTIONS LESS THAN  ELEMENTS  HAVE BEEN IN REASONABLE AGREEMENT WITH THE RESULTS PREDICTED FOR AN INFINITE ARRAY  %LEMENT 0ATTERN  &ROM ENERGY CONSIDERATIONS  THE DIRECTIONAL GAIN OF A PERFECTLY  MATCHED ARRAY WITH CONSTANT AMPLITUDE DISTRIBUTION  G      WILL VARY AS THE PROJECTED  APERTURE AREA FROM %Q    '!  C OS PP P L  )F IT IS ASSUMED THAT EACH OF THE  . ELEMENTS IN THE ARRAY SHARES THE GAIN EQUALLY  THE  GAIN OF A SINGLE ELEMENT IS FROM %Q   '! .E  C O SPP  P L  )F THE ELEMENT IS MISMATCHED  HAVING A REFLECTION COEFFICIENT  'P  E   THAT VARIES AS  A FUNCTION OF SCAN ANGLE  THE ELEMENT GAIN PATTERN IS REDUCED TO   '! .E   COS  ; \     \=PP 
 Phase ripple, if specified,  is relative to a best-fit linear phase and has similar effects as amplitude ripple. Group  delay, the rate of change of phase vs. frequency, is ideally constant for linear phase  filters. 
 Decimate by tw o 7. Complex, decimated       passband signal 8. –75 MHz complex tone 9. 
 B., Jr., P. Blacksmith, and C. J. 
 4 S-Pol: The multi-parameter S -band and Ka- band polarimetric research radar pointing at the sun for a solar  calibration at the National Center for Atmospheric Research,  Boulder, Colorado ( Courtesy of University Corporation for  Atmospheric Research © 2007 , Boulder, CO ) ch19.indd   17 12/20/07   5:38:17 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 
 30.)0=0.5 AND 1.0DETECTION PROBABILITY . Nonparametric Detectors. Usually nonparametric detectors obtain CFAR by ranking the test sample with the reference cells.31'32 Ranking means that one or- ders the samples from the smallest to the largest and replaces the smallest with rank O, the next smallest with rank 1,..., and the largest with rank n-1. 
 Because of practical considerations related to targetdetectionanddiscrimination,onlythehorizontalbeamwidthisquitenarrow,typical values being between about 0.65˚ to 2.0˚. The vertical beam width isrelatively broad, typical values being between about 15˚ to 30˚. The beam width is dependent upon the frequency or wavelength of the transmitted energy, antenna design, and the dimensions of the antenna. 
 11.4  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 The use of solid-state does not eliminate all the problems of transmitter design.  The RF combining networks must be designed with great care and skill to minimize  combining losses in order to keep transmitter efficiency high. Suitable isolation from  excessive voltage-standing-wave ratio (VSWR) must be provided to protect the micro - wave transistors from undesired operational stresses, and their harmonic power output  must be properly filtered to meet MIL-STD-469 and other specifications on RF spec - trum quality. 
 To obtain the difference beam, the analogue tapering at the element level is  compensated, at the sub-array level, to achieve an overall taper function more similar  to the Bayliss one; this is obtained by decreasing the contribution of the central sub- arrays 2 and 3.  A numerical example is reported in Farina et al.118 with an ULA of N = 24 elements  and M = 4 sub-arrays. The chosen weight is a Taylor tapering with 30 dB of PSLR. 
  /" Ê/ 
 !F F )&  IT IS NECESSARY TO SHIFT THE SPECTRUM AT THE !$ CONVERTER OUTPUT    DOWN IN FREQUENCY BY THE AMOUNT  F)& 4HIS CORRESPONDS TO A MULTIPLICATION BY THE  TIME SERIES  UI EJI 
 1624-1631, November, 1953.  93. Hougardy, R. 
 lEE(London). vol.113.pp.405-412, March.1966. 39.Barrick, D.E.:FM/CW RadarSignalsandDigitalProcessing, National OceanicandAtmospheric Administration. 
 I J. Sinsky, A. I.. 
  S  7ITH THE RANGE 
 7. W. W. 
 Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar.  PULSE DOPPLER RADAR  4.456x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 Alert/Confirm increases sensitivity by allowing more false alarms in Alert and rely - ing on Confirm to reject those false alerts. The Alert/Confirm combination is designed  to provide the same false report time TFR as a conventional waveform. 
 Tlie electrorl emission density from tlie  catliode is gclierally less than reqtrired for the electrotl beam, so a large-area cathode surface is  11set1 illid tlle criiitted clcctrolis are cslrsed to converge to a narrow beam of high electron  dcrlsity. '1'11~ riioclirlnti~tg :triode, or. otlicr I,car~t co~ltrol clcctrodc, is oftcli i~icludcd :is jxtrl ol'  tlic electrorl-guri strirctirre to provide a means for pulsing the electron beam on and off. 
 Second, s  0 implies that the data are calibrated, not  only with respect to the radiometric parameters of the radar and processor, but also  with respect to the local incident angle at the pixel location ( x,y). Although data from  ERS-1/2 are corrected to account for the mean incidence within the imaged swath,  there is no attempt to correct for slopes locally within the swath to the pixel level. An  alternative is to denote the (magnitude-squared) digital numbers as b  0, which indicates  simply radar power per pixel.31 This has become standard practice with RADARSAT-1  data, for example. 
 lEEE 7'i.arrs..  vol. Al!S-l I. 
 However, the application of absorbers is always expensive,  whether gauged in terms of nonrecurring engineering costs, lifetime maintenance,  or reduced mission capabilities. The two methods of echo control are discussed in  Section 14.5, and a collection of four stealthy platforms is surveyed there. Seven Basic Echo Mechanisms . 
 1182-1190, August, 1971.  16. Torrey, H. 
 AIRBORNE MTI  3.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 The amplitude E1 of the received signal is proportional to the two-way antenna field  intensity. The phase advance is  2 24η ππ θ λ= = f TV T d px psin  (3.7) where fd = doppler shift of scatterer (Eq. 3.4)  Tp = interpulse period Figure 3.11 b shows a method of correcting for the phase advance h. 
 The peak pulse power was 15kw, the pulsewidth 3psec, and the repetition rate 1640 pps. Range against bombers was about 70miles, against fighters about 50miles. The display was anA-scope inwhich the trace was lengthened by causing the sweep totake place from left toright across the tube, then drop down and return from right tolem Range was estimated with the help ofmarks onthe face ofthe tube; bearing was determined as the direction ofantenna-pointing which yielded maximum signal. 
 Theclassical method ofaccounting foratmospheric refraction incomputations isby replacing theactualearthofradiusa(a=3440nauticalmiles)byanequivalent earthofradius kaandbyreplacing theactualatmosphere byahomogeneous atmosphere inwhichelectro­ magnetic wavespropagate instraight linesratherthancurvedlines(Fig.12.6).Itmaybe shownfromSnell'slawinspherical geometry thatthevalueofthefactorkbywhichtheearth's radiusmustbemultiplied inordertoplottheraypathsasstraight linesis k=__---,-I_~ 1+a(dfl/dIr) wheredll/dhistherateofchangeofrefractiveindexnwithheight.5Theverticalgradientofthe refractive indexdll/dhisnormally negative.Iritisassumed thatthisgradient isconstant with heightandequaltoavalueof39x10-6permeter,thevalueofkisj.Theuseofthe1effective earth'sradiustoaccount fortherefraction ofradiowavespredates radarand,becauseofits convenience, hasbeenwidelyusedinradiocommunications, propagation work,andradar.13 Itisonlyanapproximation, however, andmaynotyieldcorrectresultsifpreciseradar measurements aredesired, as,forexample, inalong-range heightfinder.Thetermstandard rlFaction isappliedwhentheindexofrefraction decreases uniformly withaltitudeinsucha mannerthatk=1(Ref.14). Thedistance dtothehorizon fromaradaratheightIImaybeshownfromsimple geometrical considerations tobeapproximately d=J2kalr (12.1Ia) wherekaistheeffective radiusoftheearthandItisassumed smallcompared witha.Fork=t Eq.(I2.lla) reducestoaparticularly convenient relationship ifdandIraremeasured instatute milesandfeel,respectively. ---or, or, Radiusa1rr (a)d(statutemBes)=J2/1(rt) d(nautical miles)=1.23jh(ft) d(km)=130JIt(km) Radiuska 1 J(b)(12.11h) (12.llc) (12.lld) Figure12.6(0)Bendingofantenna beamduetorefraction bytheearth'satmosphere; (h)shapeofbeamin equivalent-earth representation withradiuska.. 
 Ground Echo   ........................................................... 12.1  12.1 Introducti on  .............................................................  12.1  Relative Importance of Theory and  Empiricism  ...................................................... 
 61–72, April 2002. 150. R. 
 140-153, March, 1961.  20. Morgan, S. 
 FIG. 15.2 Simplified block diagram of a coherent MTI system. from the phase information from the previous transmitted pulse. 
 Angle (deg) Noise (dBW)• = R4th Loss. = R4th + L 0 = Frequency* = El. Angle ^ 1 deg.« = Noise• = R4th Loss• = R4th -I- L 0 = Frequency* = El. 
 MEAN AND IS CHARACTERIZED BY ITS COVARIANCE  MATRIX 1TK  )F ONE VIEWS THE UNKNOWN MANEUVER AS A WHITE 
 ACCELERATIONS  2ADAR DETECTIONS OF LESS THAN THREE DIMENSIONS CAN BE EASILY ACCOMMODATED2EQUIRES FREQUENT COORDINATE TRANSFORMS 5NSCENTED +ALMAN FILTER 0OLAR OR #ARTESIAN %ARTH 
 The coverage area obscured byground clutter will increase aspulse length isincreased. Magnetron behavior has been found tobecome more critical, and requirements onthe voltage pulse from the modulator tobecome more exacting, with increasing pulse length.. 598 EXAMPLES OF RADAR SYSTEM DESIGN [SEC. 
 154, pp. 967-972. 1966. 
 As these particles tall  to the ground they melt and change to rain in the warmer environment of the lower altitudes  When this occurs, there is an increase in the radar backscatter since water particles reflect  more strongly than ice. As the ice' particles, snow, or hail begin to melt, they first become  water-coated ice spheroids. At radar wavelengths, scattering and attenuation by water-coated  ice spheroids the size of wet snowflakes is similar in magnitude to that of spheroidal water  drops of the same size and shape. 
 PULSE -4) AND -4$ ))     
 P. Steyskal, “Phased arrays 1985 symposium,” in RADC Rept.  TR-85-171, Rome Air  Development Center, Bedford, MA, August 1985. 
 TION MEASUREMENTS AT  TK 3.2K IS THE OBSERVED 3.2 AT  TK TK  IS THE COMMANDED TIME  FOR THE NEXT TARGET OBSERVATION  RK \K  BK \K  EK \K ARE THE PREDICTED RANGE  BEARING  AND  ELEVATION FOR BEAM POINTING CONTROL AT  TK  7K  IS THE WAVEFORM SELECTION AT  TK  AK   IS THE DETECTION THRESHOLD FOR THE DWELL SET AT  TK  AND 8K\K  0K\K ARE THE TARGET FILTERED  STATE ESTIMATE AND COVARIANCE MATRIX AT  TK GIVEN ALL THE RADAR MEASUREMENTS UP TO TK   &)'52%   )NTERACTION OF RADAR SCHEDULER AND TRACKING FILTER 
 1959.  22. Knop, C. 
 Hall and W. W. Shrader32  © IEEE 2007 )Returns From Target Detection  Threshold  Pulse Number 0 10 20 30 40 50 60 0 10 20 |Residue| (Volts) Clutter Residue  ch02.indd   65 12/20/07   1:45:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 However there will besome time which ischarac- teristic ofthe decay, and wecan say simply that ifthe electron beam traces repeatedly over thesame strip ofthescreen, thenumber ofsweeps averaged will beoftheorder ofthepulse repetition frequency times this decay time. Inpractice, theradar isusually scanning. That is,before thedecay time elapses, theradar beam moves offthetarget and thecath- ode-ray-tube trace moves toanew position onthescreen. 
 In order to counteract the mutual repulsion of the electrons which constilute thc electron  beam, an axial magnetic field (not shown in Fig. 6.9) is generally employed. The rnagnetic ficld  focuses, or confines, the electrons to a relatively long, thin beam, and prevents the beam from  dispersing. 
 If  M range samples are to be provided by one processor, the length of the DFT must  exceed M plus the number of samples in the reference waveform minus one to achieve  an aperiodic convolution. These added M samples are filled with zeros in the refer - ence waveform DFT. For extended range coverage, repeated processing operations are  required with range delays of M samples between adjacent operations using the over - lap-save convolution technique.49,54 This processor can be used with any waveform,  and the reference waveform can be offset in doppler frequency to achieve a matched  filter at this doppler frequency. 
 STATE VALUES ON THE FIRST )00 OF DATA )F NO CANCELER IS USED  SIGNALS CAN BE PASSED TO THE FILTER BANK AFTER THE SPACE CHARGE  IS COMPLETE  SO THAT THE COHERENT INTEGRATION TIME IS THE TOTAL #0) TIME MINUS THE SPACE CHARGE TIME !LTITUDE 
 Nakatuka, and K. Nishikawa, “Development of precipitation radar onboard the  Tropical Rainfall Measurement Mission (TRMM) satellite,” IEEE Transactions on Geoscience  and Remote Sensing , vol. 39, pp. 
 This is an almost  impossible task. In the absence of better data. it might be assumed that all range intervals are  equally probable a priori, and the a priori probability may be considered to be constant. 
 TOR WINDS !LTHOUGH THE hIMAGESv GENERATED BY A SPACE 
 CCDU took the average detection range against Grassholm over many trials and radars to normalise the results for individual trials, given actual range reported Table 7.1. Detection ranges of Grassholm Island, 1000 ft. Radar Average detection range, R, nmi Sensitivity relative to ASV Mk. 
 16.36.—Block diagram ofoscillator stability tester. other iscompared. The output signal from the mixer isamplified and applied toafrequency discriminator circuit. 
 WAVE 
 Deramp on Receive.  Satellite-based radar altimeters present an elegant embodi - ment of the Stretch technique,86 which is known as full deramp  in the field of space- based radar altimetry. This method was first employed by MacArthur in the Seasat  altimeter,70 and has been adopted as the standard technique since then for this type of  radar. 
 Thus it is usually  desirable to suppress the side lobes of the multiple receiving beams more than usual in order to  reduce the likelihood of echoes from large targets being received via the one-way sidelobes.  Multiple-beam array antennas with a large number of simultaneous beams have not seen  wide application, probably because of the complexity of such systems. They have, however,  had application in 3D mechanically rotating air-surveillance radars which employ a small  number of contiguous beams stacked in elevation to provide the elevation coordinate. 
 PERPENDICULAR  AND PARALLEL 
 However, most radar targets are of a  riiore complex nature than the sphere. Tlle amplitude of the echo signal from a complex target  may vary over wide limits as the aspect changes with respect to the radar. In addition, the  effective center of radar reflection may also change. 
 on Radar Meteorol ., AMS, Montreal, 1999, pp. 158–163. 66. 
 8, 1958.  42. Meuehe, C. 
 LIMITED DISTRIBUTED CLUTTER IS  TAKEN FROM (ALL AND 3HRADER  &IGURE  SHOWS A POLAR PLOT OF PART OF A LINEAR CLUT 
 Almost any type of digital storage device can be  used. A shift register is the direct digital analogy of a delay line, but other digital computer  memories can also be used effectively.  The A/D converter has been, in the past, one of the critical parts of the MTI signal  processor. 
 on  Radar Meteorol. , Austin, AMS, 1997, pp. 309–310. 
  
 HOC PROGRAMMING LANGUAGES SUITABLE FOR SIMULATION 3IMULATION OF A COMPLEX SYSTEM ON A DIGITAL COMPUTER IS A TECHNIQUE USED FOR THE  ANALYSIS  DESIGN  AND TESTING OF A SYSTEM WHOSE BEHAVIOR CANNOT BE EASILY EVALUATED BY MEANS OF ANALYSIS OR COMPUTATION 4HE PROCEDURE ESSENTIALLY  CONSISTS OF REPRODUC 
 Commercial applications include wind field measurements and traf - fic surveillance. Scientific applications include measurement of planetary surfaces and  atmospheres and study of ionospheric turbulence. Examples are given in Section 23.4. 
 ANTENNA APERTURE ARE FUNCTIONS OF THE ELEVATION AND AZIMUTH ANGLES   'T   'TP  E     !R   !RP  E   A  4HE DIFFERENTIAL SCATTERING CROSS  SECTION ITSELF IS A FUNCTION OF BOTH  LOOK ANGLE  P  E   AND GROUND LOCATION   R    R  P  E  LOCATION   B  4HE INTEGRAL OF %Q  MUST BE INVERTED WHEN  R  IS MEASURED 7ITH NARROW BEAMS  AND SHORT PULSES  THE INVERSION IS RELATIVELY EASY  BUT WITH THE WIDER BEAMS AND LON 
 Losses applicable  only to targets will be indicated. RF Transmit Loss.  This loss accounts for RF ohmic losses between the transmit - ter or RF power amplifier and the antenna radiator, which can include losses from  connectors, circulators, and radiating elements. 
 M  n 
 As an example, a sensor is regarded with 24 GHz, with which 5° correspond to the  change in phase of a of distance variation of approximately 40 µm.  Thus the wear due to fri c- tion can be controlled very exactly.   For the measurement of larger ranges and distances, an amplitude modulation (AM) can be  modulated on the CW signal and for the analysis, the phase of the AM can be determined. 
   2!$!2 $)')4!, 3)'.!, 02/#%33).'   Óx°Î SEEN TO BE A COMBINATION OF SPECTRAL COMPONENTS OF THE FORM  ! E JO  FT 3AMPLED SIGNALS  HAVE T   N4 WITH 4 A SAMPLING INTERVAL AND  N AN INTEGER TIME  BUT SAMPLED OR NOT  THE  BASIC COMPONENT FORM IS THE SAME !ND EITHER WAY  COMPLEX AMPLITUDE  ! IS A FUNCTION  OF FREQUENCY F  BUT LETS WRITE ! INSTEAD OF !  F   FOR SIMPLICITY )N THESE TERMS THEN  WHATS SPECIAL ABOUT REAL SIGNALS IS THAT AN EASILY DERIVED  &OURIER 
 87. H. Masuko and H. 
 Itisalsoassumed thattheerrorassociated withameasuremellt ofaparticular parameter isindependent oftheerrorsinanyoftheother paramctcrs. Thcvalidityofthisassumption depends upontheavailability ofalargesignal-to­ 1I0iseratio.(Furthcr information regarding radarmeasurements callbefoundinRef.7.) Theoretical radaraccuracies maybederived byavarietyofmethods including those bascdon(I)simplcgeometrical relationships between signal,noise,andtheparameter tobe measured. (2)inverse probability, (3)asuitably selected gatingfunction preceded bya matchcd filler,and(4)theestimate ofthevariance usingthelikelihood function. 
 This condition—known as saturation, or being  fully developed—is reached at quite modest wind speeds for those waves responsible  for first-order scatter at HF, that is 5–10 knots. Of the various nondirectional ocean wave models reported in the literature, that  of Pierson and Moskowitz has been most widely used by the radar community. They  derived the following relation for a fully developed nondirectional spectrum based  upon empirical data84:  Fe c( ) exp kb kk k= −      242 πν  (20.9)FIGURE 20.12  Nondirectional waveheight power spectral density, as measured with a wave buoy, show - ing power law behavior. 
 ING TO RESOLVE TRUE RADIAL VELOCITY USING DIFFERENT 02&S  hGHOSTSv e MAY BE CREATED  &)'52%  )LLUSTRATIVE ACCEPTANCEREJECTION CRITERIA OF 36# $" ""$ %#   !$" 
    , ((   * %+)  * 
 3.18 and 3.19, we see that for Ec to approximate the correction  signal, the difference patterns should be  ∆( )( )θ θθ θ=∑Td dp (3.20) The derivative of the sum pattern is similar to a difference pattern in that it is positive  at the main-beam null, −q0, decreases to zero on the antenna centerline, and then goes  negative until q0. Referring to Figure 3.13, one observes that the mechanization for scan compensa - tion is fundamentally similar to the DPCA mechanization except that the difference  signal is applied in phase with the sum signal and amplified by an amount determined  by the antenna rotation per interpulse period. The signals required, if the transmission signal Σ(q ) that appears in each channel  is neglected, are Σ ∆( ) ( ) θ θ θ ±l Tp, where l is the ratio of the amplification in the two  channels chosen to maximize the clutter rejection. 
 5.Burrows. CR.,andS.S.Attwood: "RadioWavePropagation," Academic Press.Inc..NewYork. 1949. 
 The Dolph-Chebyshev weighting theoretically results in all sidelobes being equal. It is of  academic interest only, since it is unrealizable. The Taylor is a practical approximation to the  Dolph-Chebyshev. 
 The coupling to the klystron and mixer current were pre-set on the ground. Figure 4.2shows control unit type 444, together with an example of its installation in a Wellington XIV [ 1]. The IF frequency was changed from 13. 
 42. Jasik. H.: "Antenna Engineering Handbook," McGraw-Hill Book Co., New York, 1961, sec. 
 /   #%+   /      "    . 
 BACKSCATTER TO IDENTIFY DEPOSITS OF CLEAN WATER ICE  ARE ALSO A UNIQUE ADVANTAGE OF BISTATIC RADAR 4HE ABILITY TO OBSERVE FORWARD SCATTERING AT LATITUDES AWAY FROM PLANETARY EQUATORS IS ALSO ADVANTA 
 L., S. R. Curley, J. 
 Unbiased operation is also known as passive. It is  used for low-power applications. Biased operation is also known as active and is capable of  switching high power.43·44•62 Biased PIN diodes can replace the gas-tube TRs of the balanced­ duplexer configuration of Fig. 
 Prices and power co n- sumption are still high, but, like those of most digital har dware, they will plummet. Appropriate  antennas with excellent features, wide bandwidths, dual p olarization and low loss are under d e- velopment.  Digital beam forming on receive only is one of the top R&D areas for the third and  fourth generations of mobile communications. 
 CHANNEL MONOPULSE  CAN PROVIDE INSTANTANEOUS !'# OR NORMALIZING BY USE OF LOG DETECTORS AS DESCRIBED LATER IN THIS SECTION 4HE SUM SIGNAL AT THE )&  OUTPUT ALSO PROVIDES  A REFERENCE SIGNAL TO PHASE DETECTORS  THAT DERIVE ANGLE 
 For random changes in accel - eration at each measurement interval (model no. 2), the gains increase to ( a, b) =�� (1,2), which is the limit of filter stability. Thus, this model produces filter gains that  are the most aggressive at minimizing lags to maneuvers—at the expense of larger  2 1.8 1.6 1.4β (Models No. 
 1B. ch05.indd   46 12/17/07   1:27:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 4.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 number of 3 on PRFs 2 and 3. The IPP lengths (often expressed in range gates per IPP )  are usually kept relatively prime (no common factors except the number 1) to permit  unambiguous ranging at the maximum possible range. The logic for correlation requires at least M detections across the N PRFs in a  dwell to declare a target report (with M typically ≥ 3 for medium- and high-medium  PRF waveforms). 
 Reflectors on these platforms generally see  particularly stressing vibration levels driven by airplane or launch vehicle (rocket)  environments. Potential exposure to salt, sand, water, etc., is highly dependent upon  platform, use of radome (or not), etc., but must be considered in the design. Radomes. 
 SURING THE PEAK RETURN LEVEL USUALLY MAIN 
 4.9NONCOHERENT MTI Thecomposite echosignalfromamovingtargetandclutterfluctuates inbothphaseand amplitude. Thecoherent MTIandthepulse-doppler radarmakeuseofthephasefluctuations intheechosignaltorecognize thedopplercomponent produced byamovingtarget.Inthese systems, amplitude fluctuations areremoved bythephasedetector. Theoperation ofthistype ofradar,whichmaybecalledcoherent MTI,depends uponareference signalattheradar receiver thatiscoherent withthetransmitter signal. 
 The result isthat theelectron, following apath ofthetype shown, eventually strikes the anode. Because ofretardation bythe r-ffield, the electron gives uptother-ffield theenergy gained initsfallthrough thed-cfield totheanode. Since the electron moves from the cathode tothe anode inavery small number ofoscillations, the condition that the electron keep step,. 
 It  has an inverse cosecant-squared elevation pattern and a 0.3° azimuth beamwidth. It  is remotely controlled to give horizontal or circular polarization. The vertical pattern  shaping interacts with the STC of the radar receiver, and it is, therefore, necessary to  take this into account in the system design. 
 M. Evans, N. Hastings, and B. 
 BASED REFLECTOR DESIGN AND SCATTERING ANALYSIS CODE DEVELOPED BY 4)#2! #OPENHAGEN  $ENMARK  4HE 3!4#/- 7ORKBENCH WAS DEVELOPED BY 4HE /HIO 3TATE 5NIVERSITY %LECTRO3CIENCE ,ABORATORY /35 
 73, pp. 182-197, February 1985. 25. 
 Acommon assumption inthedesignofmanyCFARsisthattheprobability density function ofthebackground noiseamplitude isknown(usuallytakentobegaussian) exceptfor ascalefactor.Clutter,however, isoftennonhomogeneous andthusnonstationary, aswellas beingofunknown probability densityfunction insomecases.Withsuchuncertainty inthe background, anonparametric methodofdetection mustbeused.75•78-;82(Anonparametric detector, alsocalledadistribution-free detector, initsmostgeneralformdoesnotrequireprior knowledge oftheprobability densityfunction ofthenoiseorthesigna1.39)Anonparametric detector permitsaconstant false-alarm ratetobeachieved forbackground noisethatmightbe described byverybroadclassesofprobability densityfunctions. Ithasagreaterlossthanwhen thecharacter ofthenoiseisknownandanoptimum detector canbedesigned, butitdoeskeep thefalsealarmratefixed.Oneformofnonparametric detector isbasedonthe"ranks"of observations inwhichthecomponents oftheobservations arerankedinorderofmagnitude, anddetection isbas~donlyonsomefunctionoftheseranks.39Thiscanbeimplemented witha. 394 INTRODUCTION TO RADAR SYSTEMS  rank detector which computes the ranks by pair-wise comparisons of the output from the range  cell under test with each of the outputs from the neighboring range cells that sample the  background n~ise.~'-'' After the detector ranks the sample under test with its neighboring  samples, it integrates the ranks and a target is declared after testing against a fixed and an  adaptive thresh~ld.~~*'~  There are several other methods for achieving CFAR besides the use of cell averaging. 
 J. Donaldson, Jr.: Plan Shear Indicator for Real-Time Doppler Identification of Hazardous Storm Winds, J. Appl. 
 The practice in use is to select the largest. This is a  winter daytime example at a United States east coast location. The three straight lines  are estimates of anthropogenic noise for three different types of sites. 
 they can oscillate at two different frequencies corresponding to a rotation  of the standing-wave pattern, where the positions of the nodes and antinodes are interchanged.  Tilus there arc N -I possible frequencies in which the magnetron can oscillate. The presence  of more than one possible mode of operation means that the magnetron can oscillate in any  one or these'f requencies and can do so in an unpredictable manner. 
 Nl/!'alResearch Lahoratory. Washillf/toll. D.C..Report709R.June25,1970(AD709897). 
 frequency, which allows amplification ofthe signals before addition. Second, i-flocking issuperior tor-flocking. The latter ishard todoin thecase ofthetransmitter, because ofthelarge amount ofpower required;. 
 Despite the perceived modernity of today’s chart radars,  it was connected to an optional Chart Comparison Unit , which was an optical system  allowing the radar image to be displayed in coincidence with a paper chart. The facility  to allow “North-up” operation was always seen to be a vital requirement for marine  navigation radar. Parallel trials in the United States were conducted on a number of  candidate systems, using a broad range of frequency bands. 
 16.1). Thus, if Wr(fd) is the power received between frequencies fd and  fd + dfd, the radar equation becomes  W f dfPGA d A Rr d dt t r( )( )=1 420 4πσ Illuminated area a between and f f dfd t t r d d ddf PGA R +∫=( )420 4πσ− −   ∫dA dfd     (16.12) This is an integral in which the area element between fd and fd + dfd is expressed  in terms of coordinates along and normal to the isodops. Such coordinates must be  established for each particular case. 
 Aneffec- tive r-fshort circuit, with nometallic contact between inner and outer conductor, isprovided bytwo concentric quarter-wave sections which form achoke not unlike that inarotary joint. The i-foutput fitting unscrews topermit replacement ofcrystals. Local-oscillator power isintroduced through aside arm. 
 Sensors 2019 ,19, 346   Figure 10. RCS curves of three pixels.   Figure 11. 
 OUSLY )N THE RESEARCH COMMUNITY  MULTIPLE 
 In fact,  it was 4 invention of H’ Abraham and E. Bloch at the  end of the First World War, and in view of the secrecy  which came to surround all producers of square waves  (most especially the multi-vib) during World War No. 2,  it is amusing to reflect that the enemy could have read  it all for himself in Abraham and Bloch’s Notice sur les  lampes-valves a 3-electrodes et leur applications (Publi-  cation No. 
 involves acomplctcknowlcdge oftherespollse charactcristic /-1(/).Thefrequcncy-responsc characteristics ofmanypractical radarreceivers aresuchthat thc3-dBandthenoisehandwidths do1I0tdifferappreciahly. Therefore the3-dBbandwidth maybeusedinmanycasesasanapproximation tothenoisebandwidth.2 Thenoisepowerinpractical receivers isoftengreaterthancanbeaccounted forby thermal noisealone.Theadditional noisecomponents areduetomechanisms otherthanthe thermal agitation oftheconduction electrons. For'purposes ofthepresent discussion. 
 As for the case of equal LFM slopes, the range window  width depends on the achievable processing bandwidth. Stretch Processing Range Resolution Width.  The 6-dB frequency resolution width  for spectral analysis using a rectangular window of time duration equal to the transmit  pulsewidth is   ∆fT61 21=. 
 TRA THEREFORE  THE SIGNALS CAN BE REPRESENTED BY THEIR COMPLEX ENVELOPES  WHICH MODU 
 11.29. The magnetron, type 4J52, isofthe“packaged” design; themagnet isanintegral part of thetube. Itope~ates ataninput level ofabout 200 kw, with anaverage efficiency ofabout 30per cent. 
 (ILL  . 
 The two antennas are displaced horizontally (along a line parallel to the ground)  to detect and analyze moving targets and are displaced vertically to estimate   terrain height. Both types of InSAR are discussed herein. The former is discussed  in this section and the latter is discussed later in “Interferometric SAR (InSAR) for  Target Height Measurement.” InSAR to detect moving targets was originally developed by the Jet Propulsion  Laboratory (JPL) to detect ocean currents,18,19 and has been improved by several  authors.42 One of the most sophisticated techniques has been developed for the  Joint STARS aircraft and uses an interesting combination of SAR and MTI tech - niques to detect and evaluate moving targets.21 The Joint STARS SAR mode involves a classical single-receiver-channel spotlight  SAR that dwells on a designated ground-referenced coordinate for a duration that  results in a nominally square point-spread function (i.e., downrange resolution =  crossrange resolution). 
 Three types ofvoltage-sensitive elements have been used inexperi- mental regulators. One consisted ofaVR-tube bridge excited from a transformer and rectifier connected tothe output ofthealternator tobe controlled. Asuitable filter could beadded tothe rectifier sothat regulation was performed with respect tothe peak value ofthe output waveform. 
 DIMENSIONAL $  VOLUMETRIC RADAR SEARCH IS POS 
 Sensors 2018 ,18, 3750 range resolution is generally equal to the azimuth resolution. Concerning resolution requirements, the signal bandwidth and azimuth accumulation angle can be determined through δy=c 2Band δx=λ 2θ. Concerning range resolution requirements, the frequency sampling interval is Δf≤c 2R0, also taken as step frequency interval. 
 +ALANI  - "ATISTA 
 Acoarseindication ofheightsometimes canbeobtained byrecognizing the fadingoftheechosignalasanaircrafttargetfliesthrough themultipath lobesofthe'antenna pattern. Measuring therangeatwhichthetargetisfirstseenonthebottomlobe,ortherange whereitdisappears becauseofthefirstnullofthelobingpattern,canberelatedtothetarget height.ThiselTectismoreapplicable atthelowermicrowave frequencies andforradarssited overwater.Atthehigherfrequencies wherethelobesarenarrow, acountofthelobesperunit distance canberelatedtothetargetheight.Although thetechnique ofloberfcognition is relatively 'simpleandhasbeenreported tohavebeenusedinWorldWar I1:~5itspoor reliability, lowtargetcapacity, andpooraccuracy, makeitunattractive. Time-difference heightfinding.Theseveralheight-finding techniques included inthissection weredescribed intermsofaground-based radar.Mostcanbemodified toapplytoan airborne radarforthemeasurement ofheightofotheraircraftorthedepression angleifa groundtarget.Thetime-difference height-finding technique tobedescribed isapplicable, in principle, toalmostanyradarsituation, butinpractice itismoreapplicable toanelevated radarsuchasinanaircraft, especially onewhichoperates overwater.Itderivestheheightofa targetfromthetimedifference between theradarsignalreflected directly fromthetargetand themultipath signalthatarrivesviareflection fromthesurfaceoftheearth. 
 • The window functions used to control leakage during conventional spectrum analy - sis must have sufficiently low sidelobes when transforms are to be applied directly  to high dynamic range data. The basic steps of range, azimuth, and doppler analysis are not the only stages of  signal processing. As explained in Section 20.4, HF skywave radar signals are subject   FIGURE 20.21  Noncoherently averaged power spectra from three contiguous time intervals, plotted with  an offset for clarity. 
 When cir- cular polarization is needed in a paraboloid-type antenna, square or circular cross-section horn throats are used. The vertical and horizontal components from each horn are separated and comparators provided for each polarization. The sum and difference signals from the comparators are combined with 90° relative phase to obtain circular polarization. 
 ILY MEASURED AGAINST DESIGN REQUIREMENTS 4HE DESIGN OF HIGH 
 TO 
 54. Barrick, D. E.: Theory of HF and VHF Propagation across the Rough Sea, pts. 
 E.: Advances in Radar Signal Processing, IEEE Electro '76, Boston, Mass, May 11-14,  1976.  44. [)rury. 
 Arc FMCW SAR and Applications in Ground Monitoring. IEEE T rans. Geosci. 
 S. (ed.): "Microwave Antenna Tlleory and Design," MIT Radiation Laboratory Series.  vol. 
 Farina, M. Giannelli, L. Timmoneri, and G. 
 First, the two receive beams in the low-angle technique are not formed from identical aperture illuminations. Second, the transmit beam in the low-angle technique is narrow, reducing indirect multipath returns and to a lesser degree off-boresight signal-to- noise ratio. The performance of a version of the low-angle squinted-sum-beam technique relative to that of a conventional monopulse is compared in Fig. 
 The paper proposes an algorithm based on an inverse SAR technique able to refocus only the portions of SLC matrix containing moving ships, instead of the whole raw image. Motion phase compensation is performed through an iterative procedure based on a fast minimum entropy method. The procedure was presented and validated by using both airborne data and spaceborne images acquired by TerraSAR-X and Gaofeng-3 missions. 
 RESOLUTION CENTRAL SPIKE 4HE RANGE RESOLUTION OR COMPRESSED 
 The basic procedures of refocusing moving ship in SAR image are represented in Figure 1. Ship  Detection Subimage  SelectionSubimage  InversionISAR  ProcessingSAR  ImageRefocused  Image   Figure 1. Block scheme of defocused target refocusing in SAR image. 
 Any use is subject to the Terms of Use as given at the website. Radar Receivers.  RADAR RECEIVERS  6.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 Range Sidelobes.  Errors in filter responses can produce degradation in pulse  compression range sidelobes. 
 The consensus ofitsusers isthat theAX/APS-10 fitsitsrequirements ~reil. Further improvement inlightness, convenience, and modesty of power demand will follow ongeneral advance intheart, and inparticular ondetailed attention tocomponent design. Tomention one example, the substitution ofsubminiature tubes for larger standard types will reduce bulk, weight, and po\ver consumption.. 
 SION TRACKING RADAR !CCURATE TIMING FOR THESE APPLICATIONS MAY BE ACHIEVED BY PHASE LOCKING THE LOW PHASE NOISE RADAR OSCILLATORS TO A LOW FREQUENCY REFERENCE GENERATED FROM EITHER A RUBIDIUM OSCILLATOR OR A '03 RECEIVER )N THIS CONFIGURATION  THE LONG 
 2:for i=1: Ido 3: (si,init)T=(ΦiT)†ri,(xi,init)Tc=0 4: ri,res=ri−Φisi,init 5: β0 i=0 6: Res=ε+1 7: while t<Tmaxand Res>εdo 8:ˆβt i=βt i+μ/bracketleftBig ΦH i(ri−Φiβt i)/bracketrightBig 9: λ=|ˆβt i|K+1/μ 10: βt+1 i=fλμ(βt i+μ/bracketleftBig ΦH i/parenleftBig ri−Φst i,res)/bracketrightBig/parenrightBig 11: Res=/bardblβt+1 i−βt i/bardbl2 12: t=t+1 13: end while 14: ˆsi=βt+1 i+xi,init 15: T/prime=supp (ˆsi) 16: si=ΦiT/prime†yi 17:end for 18: s(x,y)=max i|si(x,y)| Output: s(x,y) In WASAR imaging, it will cost huge amount of memory to store the measurement matrix. The azimuth-range decouple operators can be used to reduce the memory cost [ 5]. In this paper, we take BP based operators to substitute the measurement matrix and its conjugate transpose in real WASAR imaging. 
 Often, the 0 (DEGREES) . (d) (e) (f) FIG. 6.7 Paraboloidal reflector outlines, (a) Round, (b) Oblong, (c) Offset feed, (d) Mi- tered corner, (e) Square corner. 
 The reported detection ranges against submarines in table 7.2are also consistent with the modelled noise-limited detection results. If a broadside submarine is assumed to have an RCS of 30 dB m 2, then the modelled detection ranges would be 21 nmi for ASV Mk. III and about 40 nmi for ASV Mk. 
  AND RECEIVER 
 However, if the time of observation is too long, the  doppler frequency of a point P on the rotating target will not be constant and the doppler  spectrum w'll broaden with a consequent reduction in resolution. That is, there is an apparent t target acceleration which limits the resolution. The result is that there will be an optimum time  of observation, or aspect angle change, wlien attempting to image a target with the inverse  SAR technique.'"  14.2 HF OVER-THE-HORIZON RADAR~O  Frequencies at VHF or lower are seldom used for conventional radar applications because of  ttieir narrow bandwidths, wide beamwidths, high ambient noise levels, and the potential  interference from other users of the crowded electromagnetic spectrum. 
 TO 
 Generally, radar waves are restricted in the recording of the range of low- lying objects by the radar horizon. The range of the radar horizon dependsontheheightoftheantennaandontheamountofbendingoftheradarwave.Thebendingiscaused bydiffractionandrefraction.Diffraction isapropertyof the electromagnetic wave itself. Refraction is due to the prevailingatmospheric conditions. 
 17.5] THE METHOD OF INCREMENTAL ANGLE 689 are large enough toallow Vlatorest below cutoff even when on, Vlbis unnecessary. Alternative types ofvideo switches are described in Sec. 139. 
 thesignalswillbereflected bytheshortcircuitslocatedfartherdownthetransmission lines. Thesignalsatports2and3,afterreflection fromeitherthediodeswitches ortheshort circuits. combine atport4.Noneofthereflected energyappears atport1.Thedifference in palhlengthwiththediodeswitches openandclosedisD./.Thetwo-way pathD./ischosen 10 correspond tothedesiredincrement ofdigitized phaseshift.AnN-bitphaseshiftercanbe obtained bycascading Nsuchhybrids. 
 107. G. H. 
 9. Rice. S. 
 §©¶¸   ££ £    WHERE XIJ  IS THE ITH ENVELOPE 
 For airborne systems, the effects of a  superrefractive layer depend upon the position of the transmitter and receiver relative  to the layer. Both of these factors are related to the electromagnetic wave’s angle of  layer penetration. The steeper the penetration angle, the less of an effect the layer will  have upon propagation. 
 The narrowband filter "smears" the input pulse since the impulse response is approxi-  ~riately the reciprocal of tlie filter bandwidth. This smearing destroys the range resolution. If  more than one target is present they cannot be resolved. 
 22/2, pp. 1-10. 87. 
 ETERS 7HEN THE TARGETS VELOCITY PLACES ITS DOPPLER SHIFT BEYOND THOSE OF ANY CLUT 
 The direct and ground-reflected waves interfere at the target either destructively or  constructively to produce nulls or reinforcements (lobes). The lobing that results causes non-  uniform illumination of the coverage, and is an important factor that influences the capabll~ty  of a radar system.  Most propagation effects that are of importance cannot be easily included into the radar  equation. 
 It would seem a simple matter to refine these results by using instrumentation  radars operating over the wide variety of radar and environmental parameters encoun - tered in practice. But while the parameters relating to the radar system and its configu - ration, such as frequency, cell size, polarization, grazing angle at the surface, etc., can  be specified, selecting and quantifying the environmental parameters is quite another  matter. First, it has not always been clear which environmental parameters are impor - tant. 
 An equation for  detecting a target in this type of clutter background could be derived, but it is a situation not  often found in practice.  In describing the geometry of surface clutter, the incidence angle and the depression angle  are sometimes used instead of the grazing angle. These are shown in Fig. 
 292-296, IEE Publication no. 105.  87. 
 This can occur  when fixed radars are used to observe movement of the sea and the land. On land,  clutter motion is usually due to moving vegetation, although moving animals and  machines create similar effects. The radar return from an assembly of scatterers like  those shown in Figure 16.8 can change because of motion of the individual scatterers  just as it changes because of motion of the radar. 
 WIDTH JITTER MUST BE LESS THAN   $07 S  r r 
 DIMENSIONAL RADAR MEASUREMENTS &OR SIMPLICITY  A THREE 
 Some early scattering-coefficient-measurement programs worth mentioning include those of the Naval Research Laboratory,15-16 Goodyear Aerospace Corporation,12 Sandia Corporation (near-vertical data),89'90 and particularly Ohio State University.2'4 Since 1972 the largest program has been at the Uni- versity of Kansas.6-7'21-53-57'69'91 Extensive programs were also in France (Centre National d'Etudes Spatiales, Centre National d'Etudes des Telecommunications, Universite Paul Sabatier),9 the Netherlands,8 Canada Centre for Remote Sensing (CCRS; especially sea ice),17 and the University of Bern, Switzerland (snow).92 Many of the results from these programs appear in digests of the International Geoscience and Remote Sensing Symposia (IGARSS; IEEE Geoscience and Re- mote Sensing Society) and journals such as IEEE Transactions on Geoscience and Remote Sensing and on Ocean Engineering, International Journal of Remote Sens- ing, Remote Sensing of Environment, and Photogrammetric Engineering and Re- mote Sensing. Although calibrations for some of the older data were doubtful, summary pre- sentations are not available for newer data. Accordingly, Fig. 
 The  processing forms the main part of the devices.  In 2000 their size was approximately 10x10x10 cm 3.  The vision for 2010 is one of transportation support ed by several Radar sensors, as shown in  Figure 13.10 and 13.11. 
 DETECTION OF RADAR SIGNALS IN NOISE 371  Thus the amplitude spectrum or the matched filter is the same as the amplitude spectrum of the  signal, but the phase spectrum of the matched filter is the negative of the phase spectrum of the  signal plus a phase shift proportional to frequency.  The matched filter may also be specified by its impulse response /z(r), which is the inverse  Fourier transform of the frequency-response function.  00  h(t) = r H(f) exp (j2rrft) df  • -00 ( 10.4)  Physically, the impulse response is the output of the filter as a function ortime when the input  is an impulse (delta function). 
 Equal average-gain over scan I.OS 1.00 1.17 1.24  4. Equal average-beamwidth over scan 1.15 1.00 l.09 I.I I . THE ELECTRONICALLY STEERED PHASED ARRAY ANTENNA IN RADAR 329  tion of 0.691 wavelengths. 
 Figure 19.2 shows a typical Nexrad installation at Missoula, Montana. The antenna is  mounted on a tower to clear surrounding obstacles such as buildings and trees. The elec - tronic equipment is housed in one shelter and the standby generator is housed in another. 
 The persistence can be varied from a fraction of a second to several  minutes, or longer.31 From five to seven gray-scale ranges are typical.26 The direct-view  storage tube can also be obtained with two colors and the shades in between. 30  The direct-view storage tube generally is capable of less resolution than a conventional  CRT. Also, the continuous buildup on the storage medium of strong, fixed clutter echoes  when the persistence is long can result in a loss of picture quality due to a loss of resolution  and a loss of contrast caused by the brightening of the dark area immediately surrounding  the blip. 
 Pixel A represents a pixel from the lawn. Pixel B represents a pixel from the frame of the vehicle. Pixel C represents a pixel from the edge of the top-hat. 
 I. Skolnik (ed.), McGraw-Hill Book  Co.. New York. 
 The longest light waves, those of red  light, are only one-sixty-thousandth part of an inch in  length, and the shortest radar waves in commercial use  at present are half an inch. Nevertheless the bowl-fire  aerials of many radar beacons do behave just as a search-  light reflector would do, and we can beam our outgoing  radar rays so that we can detect with an accuracy of  about one yard for every mile distant.  Our aerials begin to become complicated; they beam  out and bring in the transmitted energy, and must be  efficient. 
 TION FACTOR $ HAS TRANSFER FUNCTION   (Z ZZ Z+M M$+$+   § ©¨¶ ¸· 
 The klystron has good stability and low noise so as to  enable larger MTI improvement factors to be obtained when using the doppler shift  to detect moving targets in clutter. At high power, high voltages have to be used and  protection from X-rays generated by the high voltage must be employed. However,  the MBK (multiple-beam klystron) version of the klystron can be used to achieve high  power with lower voltage. 
 RADAR SYSTEM MAY  BE OPERATED AT AN ALTITUDE  SO THAT THE RADAR HORI 
 A.: Lens Aerials at Centimetric Wavelengths, J. Brit. IRE, vol. 
 Their antennas are comprised  of passive arrays of H- and V-polarized elements, driven simultaneously 90 ° out of  ch18.indd   47 12/19/07   5:15:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 TARGET RETURNS 4HIS APPROACH  UTILIZES THE FACT THAT BOTH THE JAMMING SIGNALS AND THE TARGET RETURN COME FROM THE SAME ANGULAR DIRECTION  SO THAT THE RADARS ANGLE 
 SAVE CONVOLUTION TECHNIQUE   4HIS PROCESSOR CAN BE USED WITH ANY WAVEFORM   AND THE REFERENCE WAVEFORM CAN BE OFFSET IN DOPPLER FREQUENCY TO ACHIEVE A MATCHED FILTER AT THIS DOPPLER FREQUENCY 0ULSE #OMPRESSION 2ADAR %XAMPLES  4HERE ARE MANY RADARS UNDER DEVELOP 
 Theattack onPearlHarborinDecember, 1941,wasdetected byanSCR-270, oneofsixinHawaiiatthe time.!(Therewerealso16SCR-268s assigned tounitsinHonolulu.) Butunfortunately, the truesignificance oftheblipsonthescopewasnotrealizeduntilafterthebombshadfallen.A modified SCR-270 wasalsothefirstradartodetectechoes!fromthemoonin1946. Theearlydevelopments ofpulseradarwereprimarily concerned withmilitaryapplica­ tions.Although itwasnotrecognized asbeingaradaratthetime,thefrequency-modulated. THE NATURE OF RADAR 11  aircraft radio altimeter was probably tlie first commercial application of tlie radar principie. 
 Thewaveform generated bythetransmitter travelsviaatransmission linetotheantenna. whereitisradiated intospace.Asingleantenna isgenerally usedforbothtransmitting and receiving. Thereceiver mustbepro~ected fromdamage causedbythehighpowerofthe transmitter. 
 20.1 (Continued] Early radar height finding techniques. (#) V-beam ra- dar. (/?) Phase interferometry. 
 WIDTH IS NEEDED FOR RESOLVING TARGETS IN RANGE  FOR ACCURATE MEASUREMENT OF RANGE TO A TARGET  AND FOR PROVIDING A LIMITED CAPABILITY TO RECOGNIZE ONE TYPE OF TARGET FROM ANOTHER (IGH RANGE RESOLUTION ALSO CAN BE USEFUL FOR REDUCING THE DEGRADING EFFECTS OF WHAT IS KNOWN AS  GLINT IN A TRACKING RADAR  FOR MEASURING THE ALTITUDE OF AN AIRCRAFT  BASED ON THE DIFFERENCE IN TIME DELAY RANGE  BETWEEN THE TWO 
 Sample of focused image with the proposed algorithm (upper) compared with the standard focusing obtained via Range Doppler algorithm (lower). ERS 1—Matera. The red circle indicates the point scatterer. 
 MOTION PHENOMENA &OR EXAMPLE  MULTIFRAME $)N3!2 p ANALYSIS OF 2!$!23!4 
 S  .#!2 ACQUIRED THE (IGH 
 The effect of the load on the magnetron characteristics is shown by the Rieke diagram,  whose coordinates are the load conductance and susceptance (or resistance and reactance ).  Plotted on the Rieke diagram are contours of constant power and constant frequency. Thus  the Rieke diagram gives the power output and the frequency of oscillation for any specified load  condition. 
 One reason DBF has  been proposed for future radar is because DBF provides the radar system with a  significantly higher dynamic range than can be achieved with analog beamforming,  which has a centralized receiver. In a DBF architecture, there are N digital receivers,  one at each of the N elements or subarrays. Therefore, the dynamic range of a DBF  radar system has 10log( N) higher dynamic range than an analog beamforming radar  that utilizes the same receiver, provided the noise and distortion in each receiver are  decorrelated among all receivers.100 DBF can be implemented at either the element level101 or the subarray level. 
 Moreover, parameter design criteria in incoherent addition are derived for the best performance. With the proposed parameter optimization step, the new method has a prominent azimuth sidelobes suppression e ﬀect with a slightly better azimuth resolution, as veriﬁed by experimental results on both simulated point targets and TerraSAR-X data. Keywords: multi-pass squinted (MPS); azimuth sidelobes suppression; synthetic aperture radar (SAR) 1. 
 DELAY OR A DOUBLE 
 44. Dolph, C. L.: A Current Distribution for Broadside Arrays Which Optimizes the Relation- ship between Beam Width and Sidelobe Level, Proc. 
 -/  4HE FACTORS AFFECTING THE RANGE PERFORMANCE OF A RADAR SYSTEM ARE WELL KNOWN  AND  INCREASINGLY SOPHISTICATED DESIGN METHODOLOGIES HAVE GREATLY IMPROVED THE DETECTION OF ALL FORMS OF RADAR 4HE FINAL PROOF  HOWEVER  IS HOW THE RADAR ACTUALLY PERFORMS AT SEA !S STATED PREVIOUSLY  SHIPBORNE RADARS ARE VALIDATED AS MEETING )-/ PERFORMANCE  STANDARDS BY BEING INDEPENDENTLY TYPE APPROVED TO TECHNICAL STANDARDS ISSUED BY THE  )%# 4HE )%# STANDARDS INCLUDE DEFINED METHODS OF TESTING &OR A GIVEN TARGET AND RADAR ANTENNA HEIGHT  IT IS RELATIVELY EASY TO DEFINE AND EXECUTE A TEST TO DETERMINE THAT A POINT SOURCE TARGET WITH A SPECIFIC ECHOING AREA IS DETECTED AT A GIVEN RANGE IN A MINIMAL CLUTTER FIELD )T IS VERY DIFFICULT TO EXTEND THIS TO DETERMINE  IN A REPEATABLE AND QUANTI 
 TRACK AXIS OF THE ANTENNA  INDICATIVE OF  A DAWN 
    
 13”1 laisone inwhich the plate and cathode resistors are made equal, thus providing equal signals ofboth polarities from aunipolar input signal. Since thefeedback ratio isunity foreach output signal, this “split load” or”phase-splitting” amplifier has many ofthedesirable properties ofthe cathode follower, but thesingle- sided gain isalways less and theinternal impedance isgreater. Amplifiers forDejection-coil Currents. 
 Many ground scattering measurements have been made with systems mounted on boom trucks and helicopters. Most of these are FM-CW systems66'67 that use wide bandwidth to obtain extra independent samples rather than for fine resolution. Some use very wide bandwidth to obtain fine range resolution to locate sources of scattering.68 Most have multiple-polarization capability, and some are capable of polarimetry because the phase of two received signals with orthogonal polarization can be measured.CONSTANT RESOLUTION WIDTH BEYOND 20° CONSTANTRESOLUTIONWIDTH BEYOND30° ONE RESOLUTION WIDTHAVERAGE OVER SEVERALPULSE WIDTHSPULSE LENGTH (T) = 0.1^s-, 0.2^sALTITUDE = 2,000mWAVELENGTH =10cmNUMBER OF INDEPENDENT SAMPLES . 
 ULAR REGIONS ARE APPROACHED  ON THE OTHER HAND  THE PHASE VARIATION SLOWS DOWN AND THEN REVERSES AS THE SPECULAR POINT IS CROSSED 4HIS RESULTS IN A NONZERO SPECULAR CONTRIBUTION TO THE INTEGRAL 4HE PHASE VARIATION NEAR THE SHADOW BOUNDARIES IS RAPID  HENCE  SURFACE CONTRIBUTIONS THERE ARE IGNORED IN A STATIONARY PHASE EVALUATION  BUT AN EXACT EVALUATION INCLUDES THEM BECAUSE THE SHADOW BOUNDARIES ARE THE LIMITS OF INTEGRATION "ECAUSE THE ACTUAL SURFACE FIELD DISTRIBUTIONS DO NOT SUDDENLY DROP TO ZERO AS THE SHADOW BOUNDARY IS CROSSED  AS ASSUMED BY THE THEORY  THE  SHADOW BOUNDARY CONTRIBUTIONS ARE SPURIOUS    4HUS  A STATIONARY PHASE APPROXIMATION OF THE PHYSICAL OPTICS INTEGRAL OVER CLOSED CURVED SURFACES TENDS TO BE MORE RELIABLE THAN AN EXACT EVALUATION OF THE INTEGRAL 7ITH THIS IN MIND  THE STATIONARY PHASE RESULT FOR A CIRCULAR CYLINDER IS   RP P KAK K@@ @SIN SIN   SIN    WHERE A  IS THE RADIUS OF THE CYLINDER   @ IS ITS LENGTH  AND  P IS THE ANGLE OFF BROADSIDE  INCIDENCE %QUATION  INCLUDES ONLY THE CONTRIBUTION FROM THE CURVED SIDE OF THE &)'52%   0/ PATTERNS OF THE 2#3 OF A SQUARE PLATE    A DISK  AND SECOND SQUARE PLATE . £{°Ó{  2!$!2 (!.$"//+  CYLINDER AND NOT ITS FLAT ENDS  WHICH MAY BE INCLUDED BY USING THE PRESCRIPTION OF   %Q  %QUATION  MAY ALSO BE USED TO ESTIMATE THE 2#3 OF A TRUNCATED RIGHT  CIRCULAR CONE IF THE RADIUS A IS REPLACED BY THE MEAN RADIUS OF THE CONE AND  @ IS REPLACED  BY THE LENGTH OF THE SLANTED SURFACE !LTHOUGH THE THEORY OF PHYSICAL OPTICS OFFERS A SIGNIFICANT IMPROVEMENT OVER GEO 
 14. pp. 9-10, July. 
 A number of other methods of path determination are available: for ex- ample, a path approximation technique goes with each of the ionospheric models mentioned in Sec. 24.9. For the performance exhibits treated here, the NRL-ITS Radar Performance Model will be used. 
 (Hamming Weighting) (8.35) Range Window Width.  The width of the range window is established by the band - width of the spectral analysis and the LFM slope of the transmit waveform. Assume a time  window of width ∆t and a stretch processing bandwidth Bp. 
 December, 1975.  9 I. Tomiyasu. 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.60  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 In addition to the usual GPR considerations, two space-specific issues arise, neither  of which can be solved by the usual expedient of increasing the radar’s transmitted  power. The first problem is clutter. 
   ALSO AT 3 BAND  USING A SOLID 
 D. M., and D. H. 
 (1.7) shows the  range to be independent of 1. The correct relationship depends on whether it is assumed the  gain is constant or the effective area is constant with wavelength. Furthermore, the introduc-  tion of other constraints, such as the requirement to scan a specified volume in a given time,  can yield a different wavelength dependence. 
 #  'ERMANYS 3!2 
 1960. 22.Gallop,M.A.,Jr.,andL.E.Telford: Estimation ofTropospheric Refractive Bending fromAtmos- phericEmission Measurements, RadioScience,vol.8,pp.819-827, October, 1973.. 2.1.Millman.9.H.:Atmospheric EffectsonVHFandUHFPropagation, Proc.IRE,vol.46. 
 The temporal beam separation is such that sea clutter can be  decorrelated between the beams, further enhancing the detection of targets in clutter.  This technique could potentially be used by solid-state CMRs. (Section 22.4). 
                  
 Consequently, its peak power  is significantly greater than its mean power. This is not the case with stepped frequency  whose radiated power per spectral line is higher than the time-domain radar that gives an  advantage in terms of transmitter peak signal capability compared with the impulse GPR. 21.6 MODULATION TECHNIQUES There are three main modulation techniques: time domain, frequency domain, and  pseudo-random-coded radar. 
 AP-16, pp. 103-108, January, 1968.  63. 
 325–328. 22. Casteel, C.; Gorham, L.; Minardi, M.; Scarborough, S.; Naidu, K.; Majumder, U. 
 14,   pp. R1 to R54, August 1998. See also  F. 
 FREQUENCY SPECTRUM OF AMPLITUDE NOISE  THE !'# CHARACTERISTICS WHICH DETERMINE TO WHAT EXTENT THE SLOW FLUCTUATIONS ARE SMOOTHED   AND THE ANGLE NOISE 4HE EFFECTS ON ANGLE NOISE ARE DESCRIBED LATER IN THIS SECTION  WHERE IT IS DESCRIBED WHY A FAST 
 Consequently, stalo sta- bility needs to be computed for several time delays. FIG. 3.4 Ei'lcct ot range delay on clutter cancellation. 
 H. Unal, H.W. J. 
 84, pp. 1830–1851, December 1996.) Like Keller, Ufimtsev relied  on the approximate (wide-angle) solution of the two-dimensional wedge problem, but  he distinguished between “uniform” and “nonuniform” induced surface currents. The  uniform currents were none other than the surface currents of physical optics, whereas  the nonuniform currents were taken to be undefined filamentary currents along the  edge itself. 
 This isnecessary torealize the full gain insensi- tivity tobeexpected from thelo~g pulse. The bandwidth isstill 5times the reciprocal pulse length, rather than thevalue of1to2times estab- lished asoptimum inSec. 2.9. 
 103. Giaccari, E., and G. Nucci: A Family of Air Traffic Control Radars, IEEE Trans.. 
 R. J.: Gain of Tchcbycheff Arrays, IEEE Trans .. vol. 
 5.6 TRACKING IN RANGE=*' -  In most tracking-radar applications the target is continuously tracked in range as well as in  angle. Range tracking might be accomplished by an operator who watches an A-scope or  J-scope presentation and manually positions a handwheel i~ order to maintain a marker over  the desired target pip. The setting of the handwheel is a measure of the target range and may be  converted to a voltage that is supplied to a data processor. 
 /UTPUT 4UBE  AS DISCUSSED LATER IN  3ECTION   !NOTHER APPROACH TO SPECTRUM IMPROVEMENT IS  TO SHAPE THE RISE A ND FALL OF A RECT 
 l33.Mattingly, R.L.:RadarAntennas. chap.25of"Antenna Engineering Handbook." H.Jasik.(ed.). McGraw-Hili BookCompany, NewYork,1961,sec.25.2. 
 RO. llnlph, C. L: A Current Distribution for Rrnadside · Arrays Which Optimizes the Relationship  between Beamwidth and Side Lobe Level, /'roe. 
 t) results in the following form of the radar equation:  (2.7)  Before continuing the discussion of the factors involved in the radar equation, it is  necessary to digress and review briefly some topics in probability theory in order to describe  the signal-to-noise ratio in statistical terms. 20 INTRODUCTION TO RADAR SYSTEMS  2.4 PROBABILITY-DENSITY FUNCTIONS  The basic concepts of probability theory needed in solving noise problems may be found in  any of several references.4-8 In this section we shall briefly review probability and the  probability-density function and cite some examples.  Noise is a random phenomenon. 
 MISSION LOSSES INTO THE  SOIL AND THE EFFECTIVE RADAR CROSS SECT ION OF THE TARGET  WHICH  COMPRISES ITS TRUE RADAR CROSS SECTION AND REFLECTION LOSS FROM THE TARGET .OTE THAT  A CONDUCTING REFLECTOR WILL HAVE LOW RETURN LOSS WHEREAS A NONCONDUCTING REFLECTOR WILL HAVE A HIGH RETURN LOSS )N &IGURE   THE CALCULATION HAS BEEN DERIVED FROM  METER TO  METERS AS THE RADAR RANGE EQUATION IS NOT AN ACCURATE MODEL IN THIS RANGE LESS THAN  METER AND THE PURPOSE OF THE EXPLANATION IS TO PROVIDE A BASIC INTRODUCTION TO FIRST ORDER SIGNAL ESTIMATION 2EFLECTION )N ANY ESTIMATION OF RECEIVED SIGNAL LEVEL  IT IS NECESSARY TO CONSIDER  THE COEFFICIENTS OF REFLECTION AND TRANSMISSION  AS THE WAVE PASSES THROUGH THE DIELECTRIC TO THE TARGET AND 3NELLS ,AWS DESCRIBE THE ASSOCIATED ANGLES OF INCIDENCE  REFLECTION  TRANSMISSION  AND REFRACTION 7HERE LOSSY MATERIALS ARE INVOLVED  COMPLEX ANGLES OF REFRACTION MAY OCCUR UNLIKE THE SIMPLE CLASSICAL CASE  AND POLARIZATION AND THE 3TOKES MATRIX MAY ALSO BE REQUIRED FOR ORIENTED HIGH 
 Adiagrammatic representation ofatraveling-wave tubeisshowninFig.6.11.Theelec­ tronopticsissimilartotheklystron. Bothemploytheprinciple ofvelocity modulation to density-modulate theelectron beamcurrent. Electrons emittedbythecathodeofthetraveling­ wavetubearefocusedintoabeamandpassthrough theRFinteraction circuitknownasthe slow-wave structure, orperiodic delayline.Anaxial magnetic fieldisprovided tomaintain the electron-beam focus,justasintheklystron. 
 S.. and R. H. 
 SINC ==RECT  T4    WHERE THE SINC FUNCTION IS DEFINED AS  SINCX    SINO X OX   4HE MATCHED FILTER TIME RESPONSE FOR A TARGET WITH DOPPLER SHIFT   F D IS OBTAINED BY THE  SUBSTITUTION T   nT IN THE AUTOCORRELATION FUNCTION  YT TF T4 F T4 TUD D        ; \ \=    \ 
 Óä°{n  2!$!2 (!.$"//+  2ECIPROCAL -IXING  !NALOG RECEIVERS OF HETERODYNE DESIGN GENERALLY INVOLVE A  NUMBER OF LOCAL OSCILLATORS FOR SIGNAL MIXING AND PERHAPS A WAVEFORM GENERATOR USED  TO IMPLEMENT A MATCHED FILTER  4HESE ANCILLARY SOURCES ARE INEV ITABLY OF FINITE SPECTRAL  PURITY  WITH A PHASE NOISE FLOOR THAT MAY EXTEND OVER A WIDE BAND OF FREQUENCIES  ALBEIT AT A VERY LOW LEVEL !NY POWERFUL INTERFERING SIGNALS ENTERING THE FIRST MIXER STAGE OF THE RECEIVER WILL COMBINE WITH THE PHASE NOISE FLOOR AND POTENTIALLY GENERATE PRODUCTS IN THE RADAR SIGNAL BANDWIDTH   )N THE CASE OF DIGITAL RECEIVERS  SAMPLING NOISE WILL  HAVE AN EQUIVALENT EFFECT $IGITAL 2ECEIVER 4ECHNOLOGY  (& RECEIVERS CAN EMPLOY DIRECT DIGITAL CONVER 
 23.5 Velocity-azimuth-display geometry for mea- suring horizontal wind with a single doppler radar. Mea- surement of the radial velocity for a complete azimuthal scan (p) permits measurement of horizontal winds. A harmonic analysis can be used to obtain Vh, the horizontal wind speed, the wind direction, and V/, the particle fall speed. 
 The improved interpolation is: ky=/radicalBig k2r−k2x−/bracketleftBigg/radicalBig k2rc−k2xc−kxc/radicalbig k2rc−k2xc(kx−kxc)/bracketrightBigg (16) where krc=4πfc c,kxc=2πfac cand fac=2vsinθ λis Doppler center. The residual phase after interpolation is θSTOLT/parenleftbig ky,kx/parenrightbig=−(Rb−RS)/bracketleftBigg ky+/parenleftBigg/radicalBig k2rc−k2xc−kxc/radicalbig k2rc−k2xc(kx−kxc)/parenrightBigg/bracketrightBigg −kx(Xi−Rstanθ)(17) Since the interpolation introduces a linear phase that varies with range, it is necessary to compensate for the introduced linear phase in the Range–Doppler domain. After IFFT along the range, the following is obtained: sRD(Y,kx)= A2sin c/parenleftBigBky 2πY/parenrightBig Wa/parenleftBig vkx 2π/parenrightBig exp{−jkx(Xi−Rstanθ)} ·exp/braceleftbigg −j(Rb−RS)/parenleftbigg/radicalbig k2rc−k2xc−kxc√ k2rc−k2xc(kx−kxc)/parenrightbigg/bracerightbigg(18) where Bkyis the bandwidth of ky,Y=Rb−RS, and the second phase in Equation (18) needs to be compensated along azimuth, and the azimuth compensation function is: HAZIMUTH (Rb,kx)=exp/braceleftBigg j(Rb−RS)/parenleftBigg/radicalBig k2rc−k2xc−kxc/radicalbig k2rc−k2xc(kx−kxc)/parenrightBigg/bracerightBigg (19) Multiply Equation (18) and Equation (19) and perform IFFT along azimuth to obtain: sRX(Y,Xi)= A3sin c/parenleftbiggBky 2πY/parenrightbigg sin c/parenleftbiggBkx 2π(Xi−Rstanθ)/parenrightbigg (20) where Bkxis the bandwidth of kx. 
 23. Kuttikkad, S.; Chellappa, R. Non-Gaussian CFAR techniques for target detection in high resolution SAR images. 
 LAR ESTIMATES OF THE AZIMUTH POSITION OF THE TARGET 3WERLING CALCULATED THE STANDARD  DEVIATION OF THE OPTIMAL ESTIMATE BY USING THE #RAMER 
 Technol. , vol. 4, p. 
 The orbit of Cosmos 1500 allowed complete earth coverage each 1.41 days for the optical sensors and each 5.9 days for the radar sensor. Subsequent launches of the Cosmos 1500 type of satellite have occurred. 22.4 TECHNOLOGY The desire to develop large radars in space has stimulated progress in several new technologies such as (1) large deploy able parabolic and phased array anten- nas, (2) lightweight, low-cost monolithic microwave integrated circuit (MMIC) transmit/receive modules, (3) high-level prime power systems, (4) efficient on- board signal processors, (5) large lightweight space structures, (6) lightweight, low-cost phase shifters, (7) radiation-hardened electronic devices, (8) materials with a low thermal coefficient of expansion, and (9) advanced calibration and self-test techniques. 
 SCAN COMPENSATION BECAUSE THE SYSTEM ELEC 
 TRATED IN &IGURE  FOR THE CASE WHERE THE APERTURE IS PARALLEL WITH THE RADARS PLATFORM VELOCITY VECTOR 4HE FIRST PULSE RETURNS PHASE CENTER IS ADVANCED BY APERTURE WEIGHT 
 A. Farina and L. Ortenzi, “Effect of ADC and receiver saturation on adaptive spatial filtering of  directional interference,” Signal Processing , Elsevier, vol. 
 Remote Sensing , vol. 30,   pp. 246–257, 2004. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 7 .48  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 When the probability of detection is much less than unity, the measurement-to-track  fusion is considerably more accurate. 
 BAND  NEAR  -(Z   SAY  MAY EXCEED n D"7(Z AND WILL GENERALLY EXCEED n D"7(Z  COMPARED WITH TYPICAL RECEIVER INTERNAL NOISE SPECTRAL DENSITIES OF PERHAPS n D"7(Z 4HUS  UNLIKE THE MICROWAVE RADAR CASE  EXTERNAL NOISE IS ALMOST ALWAYS DOMINANT 4HIS HAS FUNDAMENTAL IMPLICATIONS FOR RECEIVING SYSTEM DESIGN AND SIGNAL PROCESSING !NOTHER CRITICAL ISSUE IS THE OBSERVED SYSTEMATIC VARIATION OF THE EXTERNAL NOISE LEVEL  WHICH HAS A DIRECT IMPACT ON RADAR PERFORMANCE 4HE MAJOR SOURCE OF QUASI 
  XPK =      VSK    VSK  
 The fields are typically represented as the sum of known and unknown compo- nents (incident and scattered fields), and the boundary conditions are the known relationships that must be satisfied between the fields (both electric and mag- netic) just inside and just outside the surface of the obstacle exposed to the inci- dent wave. Those boundary conditions are particularly simple for solid conduct- ing or dielectric objects. The boundary conditions involve all three components of the vector fields, and the surface of the body must coincide with a coordinate of the geometrical system in which the body is described. 
 Phase Modulation   Phase modulation can also be used to differentiate segments  of a pulse in a similar  fashion as frequency hopping. Pulse  phase modulation is often implemented as a vers ion of Binary  Phase -Shift Keying (BPSK). There are specific phase codin g  schemes, such as Barker Codes to  ensure orthogonality of the  coding while providing excellent range resolution. 
 TO 
 (S/N) n = S/N for one pulse of the same probability of detection Pd and false alarm  rate Pfa with the integration of n pulses.  Then one obtains:    € n⋅E(n)=I(n)=(SN)1 (SN)n     (8.13)  I(n) is the integration factor.  Near this factor the power of the Radar can be reduced by the  integration in relation to the case, which is not integrated. 
 WAVE CONTRIBUTIONS !PPROXIMATE -ETHODS  !PPROXIMATE METHODS FOR COMPUTING SCATTERED FIELDS  ARE AVAILABLE IN BOTH THE 2AYLEIGH AND THE OPTICS REGIONS 2AYLEIGH 
 13,Sec. 6.17, Radiation Laboratory Series.. SEC, 39] ACTUAL COMPLEX TARGETIS 75 dev~ce todistinguish small targets oflarge radar cross section from large complex targets such asSKIPS byobser~-ing the change insignal intensity caused byachange inwavelength. 
 :G 0.6  L  -~ 0.4  0 a:; 0.2  0:::  0 0 1/r2 2/r2 3/r2 4/'2 5/r2  Frequency  ( b)  1.0  Q,.\ g 0.8  a  ::l 0.6 ·  L  ~ 0.4 -~ 0.2  a:: 0  1/r2 1/Tj Z/r2 2/Tj 3/r2 3/,; 4/r2 4/r. 5/,; 0  1, 2  Frequency  ( C)  Figure 4.16 (a) Frequency-response of a single-delay-line canceler for/,.= 1/T1; (b) same for/,.= l/T2;  (c) composite response with Ti/T2 = ! .  repetition fr~quencies are in the ratio of 5 : 4. 
 However, care must be taken in this practice, because K is a strong function of the antenna beamwidth and of the tar- get angle of arrival relative to the position of the beams in angle space. As ex- pressed above, K includes the signal-to-noise-ratio dependence on the target an- gle through the two-way pattern of the beam. An alternative formulation could leave this pattern factor in the signal-to-noise ratio and omit it from the definition of K. 
 Instrument mass is  465 kg; required input power is 250 W. The ionospheric sounding mode on MARSIS (described above) is aimed primar - ily at characterization of the Martian ionosphere152 during daylight conditions from  altitudes below 1200 km. The radar is operated as a stepped-frequency instrument,  sweeping 100 kHz to 5.4 MHz in 10.937 kHz intervals, over 7.38 seconds. 
 116. I. Zawadzki, “Factors affecting the precision of radar measurements of rain,” in 22cd Conf. 
 12.39  Vegetation  .........................................................  12.41  Snow  .................................................................  12.42 Sea Ice  .............................................................. 
 Despite SAR data processing being a well-established imaging technique, the proposed algorithm aims to exploit the SAR coherent illumination, demonstrating the possibility of extracting the reference functions, both in range and azimuth directions, when a strong point scatterer (either natural or manmade) is present in the scene. The Singular Value Decomposition is used to exploit the inherent redundancy present in the raw data matrix, and phase unwrapping and polynomial ﬁtting are used to reconstruct clean versions of the reference functions. Fairly focused images on both synthetic and real raw data matrices without the knowledge of mission parameters and ancillary data information can be obtained; as a byproduct, azimuth beam pattern and estimates of a few other parameters have been extracted from the raw data itself. 
 TIVE TO EXAMINE HOW SEVERAL MODES ARE GENERATED AND PROCESSED TO UNDERSTAND WHY THE WAVEFORMS MUST BE THE WAY THEY ARE -EDIUM 02& TRADES LONG 
 The relationships for a double-delay (three-pulse) AMTI are shown in the phasor diagram, Fig. 16.16. The phase advance between the first pair of pulses, received by the sum pattern 2, is 4irJj ( cor7;\ / urTp \1 \\ = -H M sin 02 - sin —-1 + VJ cos —- - cos O2 I (16.20) A L \ Z/ \ Z /J and the phase advance between the second pair of pulses is ^TP\ ( o>rTp\ ( O)7T. 
 24.17. The target RCS is labeled "size" and is considered constant. 1. 
 43. Kaisel, S. F.: Microwave Tube Technology Review, Mrcrowuve J., vol. 
 In addition to  providing the reference signal. the output of the coho.fc is also mixed with the local-oscillator  frc4uem:y J1• The lot:al ost:illator must also be a stable oscillator and is called sralo, for stable  local oscillator. The RF echo signal is heterodyned with the stalo signal to produce the IF  signal j11sl as in lhc convenlional superhetcrndyne receiver. 
  AMPLIFIER CONFIGURATION TO DEVELOP MORE THAN  7 PEAK POWER OUTPUT OVER THE  TO  -(Z FREQUENCY BANDWIDTH %ACH TRANSISTOR WAS A  7 PEAK 
 This requirement imposes a  minimum area constraint on the SAR’s antenna. The lower and upper bound PRF  constraints of BDop and 1/ TR lead to  D D RV cEl Az SC Inc >4 ( / )tan λq (18.4) where the antenna area is the product of its length DAz and height DEl, and q  Inc is the  mean incident angle in the imaged swath. The range-velocity product in this expres - sion is determined by the parameters peculiar to the particular planet (or moon) about  which the SAR is to operate (Table 18.1). 
 [ 11], thus verifying the effectiveness of the simulation. 4.2. Inﬂuence of Wind Direction During the simulations, the wind directions are deﬁned as the angle counterclockwise from the x axis of the current ﬁeld in degrees and were selected as 45◦, 135◦, 225◦, and 315◦respectively. 
 11.15 through 11.17. The B-26 pattern in Fig. 11.15 was measured at a wavelength of 10 cm (frequency of about 3 GHz); the polar format is useful for display purposes but is not as con- venient for detailed comparisons as a rectangular format is. 
 OF 
 Therefore, referring to Figure 4.6, the  gate width tg equals the transmitted pulse tt. In Figure 4.20, the IPP is 5 tg. The plots on  the left represent a range gate spacing of ts equal to tg. 
 6.23.--l~ange-height indicator of desired target. The beamwidth cfType 13. 6°ischosen tobewide enough topermit Type 13uperation with aPPI radar having very poor resolution. 
 ALARM PROBABILITY  0FA VERSUS THRESHOLD FOR MOVING WINDOW  4HE NOISE IS 2AYLEIGH 
 CONTROLLED VARIABLE 
 R. A. Dana and D. 
 Zrnic, and D. S. Sirmans: Doppler Weather Radar, Proc. 
 and 16 mm/h equals 42 dBz. (This may be an incorrect usage  of the precise definition of decibels as a power ratio, but it is the jargon used by the radar  meteorologist.) . 502 INTRODUCTION TO RADAR SYSTEMS  Scattering from snow. 
 If changes in the false-alarm rate are gradual, an operator viewing a display can compen-  sate with a manual gain adjustment. It has been said75 that the maximum increase in noise  level that can be tolerated with a manual system using displays anj operators is from 5 to  10 dB. But with an automatic detection and tracking (ADT) system, the tolerable increase is  less than 1 dB. 
 Electronics Tech. Rept. 248, Oct. 
 Peak radiated power is 10 W. The system noise floor is about 50 dB below the  mean surface return, which establishes the dynamic range that limits depth of penetra - tion. MARSIS has performed as intended,147 with early results from the polar layered  deposits, for example. 
 TIME 
 If the test object is held within one  or two focal lengths of the reflector and if the reflector is excited by a suitably designed  feed, the reflected wave is sensibly planar.61 However, unless the edges of the reflector are carefully designed, the incident field  in the target zone will be contaminated by undesired fields diffracted from the edges  of the reflector. The diffraction causes ripples in both the amplitude and the phase of  the field distribution in the target zone. In some cases, the effect is small enough to  be ignored, but in high-quality installations, the ripple may be objectionably large. 
   . Ó{°Îä  2!$!2 (!.$"//+  3UPERRESOLUTION  4HE RESOLUTION OF A CONVENTIONAL ANTENNA IS LIMITED BY THE WELL 
 122-131, June,  1957.  37. Wald, A.: "Sequential Analysis," John Wiley & Sons, Inc., New York, 1947. 
 DRIVEN WAVES  EVEN IF THERE IS A SUBSTANTIAL SWELL IN THE REGION 6ECTOR 7IND 2ETRIEVAL  4HE NORMALIZED BACKSCATTER COEFFICIENT  R    FROM A WIND 
 For  a low-sidelobe design, either CW or pulsed, the sidelobes for this feed should be cal - culated because a change in frequency no longer produces a translated beam but rather  a broader beam composed of two translated beams. Space Feed . The space (optical) feed can be considered to be somewhat between  a parallel feed and a center-fed series feed. 
 S is the salinity of water  content in parts per thousand, ev = ev = jev″ is the complex dielectric  constant in Fm−1, and mv is the volumetric moisture content in kgm−3.  (after F . T. 
  D" AT A   n 4HIS RATHER SEVERE LOSS WAS MEASURED UNDER SPECIAL CONDITIONS LOW GRAZING ANGLES  FOR TARGETS WITH VERTICAL SURFACES  AND DIHEDRALS AND TRIHEDRALS  WHICH GENERATE A LARGE MONOSTATIC 2#3 4HUS  THE BISTATIC 2#3 BECOMES SIGNIFICANTLY LOWER AS THE BISTATIC ANGLE INCREASES DUE TO SHADOWING AND LOSS OF THESE SPECULARS AND RETRO 
 NALS  AND SIGNAL PROCESSING CIRCUITRY MUST BE EXTREMELY STABLE n )N MOST CASES  THE  MAJOR CONCERN IS WITH SHORT 
 RION AFTER 7 ' "ATH ET AL . 
 PLASTIC MATERIALS v  -ICROWAVES   PP n  $ECEMBER   % & +NOTT AND 4 " ! 3ENIOR  h3TUDIES OF SCATTERING BY CELLULAR PLASTIC MATERIALS v 5NIVERSITY OF  -ICHIGAN  2AD ,AB 2EPT  
 The zoomed in patch of the same zone in Figure 10is shown in Figure 11. From Figure 11,w e can see that the imaging results with 64 pulses are much clear than that with 32 pulses for the same imaging algorithm. Moreover, the image based on FFT method under 32 pulses is the most blurred while the image based on the proposed KA-DBS method under 64 is the most clear. 
 The Rayleigh approximation is generally applicable below C band (5 cm wavelength)  and, except for the heaviest rains, is a good approximation at X band (3 cm). Rayleigh  scattering usually does not apply above X band. Another complication at frequencies above X  band is that the attenuation due to precipitation precludes the making of quantitative measure­ ments conveniently. 
 Grasso, G.: Improvement Factor of a Nonlinear MTI in Point Clutter, IEEE Truru., vol. AES-4.  pp. 
 $OPPLER !PPLICATIONS AND 2EQUIREMENTS 4!",%  #OMPARISON OF -4) AND 0ULSE $OPPLER 2ADARS FOR !IR 
 TO 
 Technol ., vol. 3, pp. 400–413, 1986. 
 M. R. Drinkwater, R. 
 Motived by the above problems in traditional InISAR imaging methods, this paper proposes the interferometric near-ﬁeld 3-D imaging based on multi-channel joint sparse reconstruction. Firstly, a more universal multi-channel interferometric near-ﬁeld echo signal model is set up; secondly, the two observed full apertures are divided into several sub-apertures according to the same criteria. By analyzing sparse characteristics of the target echo in each channel, a joint sparse constrained optimization model is set up and the problem of multi-channel high-resolution imaging is transformed into an optimization problem based on multi-channel joint sparse reconstruction. 
 "  *APAN     8 -ULTIMODE 0!,3!2  *APAN  n , 6ARIOUS TO 1UAD *IAN"ING 
 13.5.)  A knowledge of the statistics of the clutter is important in order to properly design a  CFAR (constant false-alarm rate) recei~erl'~ and to avoid the loss associated with a receiver  detector designed on the basis of the improper statistical model of clutter.  Theory of sea clutter. In the past, attempts were made to explair, the mechanism of sea clutter  by reflection from a corrugated surface,16 by backscatter from the droplets of spray thrown by  the wind into the air above the sea s~rface,'~.'~ or by backscattering from small facets, or  patches, on the sea surface." None of these models were able to explain adequately the  eAperimental observations. 
 The filament was heated bythe alternator output through atransformer, and the anode. 564 PRIME POWER SUPPLIES FORRADAR [SEC. 14.5 excited from the d-c power supply. 
 4.2. A gas-tube duplexer (Fig. 4.20) uses the presence of high power during trans- mit to fire the gas-filled T/R (transmit/ receive) "tubes," which are actually just sections of transmission line filled with a low-breakdown-voltage gas, to direct the transmitter power to the antenna. 
 4IME !DAPTIVE 0ROCESSING  2 +LEMM ED   ,ONDON  5+  )%% 2ADAR  3ONAR AND .AVIGATION  3ERIES     PP n  ! &ARINA  ! !VERBOUCH  $ 'IBOR  , ,ESCARINI  3 ,EVIT  3 3TEFANINI  AND , 4IMMONERI  h-ULTI 
 The nodding-beam height  finder scans its beam in elevation by mechanically rocking the entire antenna. It is possible to  mechanically slew a nodding-beam height finder a full 180° in a relatively short time (within  two seconds, for example). With an operator making a height measurement manually, from  2 to 4 measurements per minute might be made. 
 Hsiao. J. K .• and F. 
 Another approach, applicable with a  fixed antenna, is to not use the full synthetic antenna length L, to achieve a resolution 6,, , but  to break up the synthetic length into m subsections and look at the scene from slightly different  aspects each with a resolution m 6,,. The m independent images are then combined non-  coherently into a single image. It has been suggested that the noncoherent combining of  images of lesser resolution produces a better image with less speckle than a single image of  greater  resolution."^"  If the SAR is mapping a scene in which there are moving objects such as cars or trains, the  resulting image will be smeared in range and shifted in the along-track dimension due to the  radial motion of the object. 
 NOISE AND CLUTTER 
 BASED MICROWAVE FACILITY v  )'!233  VOL   PP n    % 3TOTZER  6 7EGMULLER  2 (UPPI  AND # -ATZLER  h$IELECTRIC AND SURFACE PARAMETERS RELATED  TO MICROWAVE SCATTER AND EMISSION PROPERTIES v $IG )'!233   PP n    4 .AGLER AND ( 2OTT  h2ETRIEVAL OF WET SNOW BY MEANS OF MULTITEMPORAL 3!2 DATA v  )%%%  4RANS ON 'EOSC AND 2EMOTE 3ENSING  VOL   PP n    & * *ANZA  2 + -OORE  AND " $ 7ARNER  h2ADAR CROSS 
 Expressed interms of impedances, the short-circuited quarter-wave section ofguide presents anopen circuit atthe probe. Then th~ load seen atthe probe isonly a single unit ofguide impedance, rather than two units inseries. Such a probe lowers the breakdown potential ofthe guide. 
 M.: Automatic Volume Control as a Feedback Problem, Proc. IRE, vol. 36, pp. 
    
 S &ROM THE S  THE RANGE OF APPLICATIONS HAS BEEN EXPANDING STEADILY  AND NOW INCLUDES THOSE GIVEN IN 4ABLE   0URPOSE 
 MENT OF ELECTRONIC SCAN PHASED ARRAY TECHNOLOGY HAS RESULTED IN VERSATILE HIGH PRECI 
 IRE, vol. 44, pp. 609-638, May, 1956. 
 12.3 Measured moisture dependence of the dielectric con- stant of corn leaves at 1.5, 5.0, and 8.0 GHz. S is the salinity of water content in parts per thousand, ev = €v - Je1," is the complex dielectric constant in Fm"1, and mv is the volumetric moisture content in kg-m~3. (After Ulaby, Moore, and Fung.21) The roughness of surfaces (especially natural ones) is difficult to describe mathematically but easy to understand qualitatively. 
 LEVEL 33( ACCURACY REQUIRED OF THESE INSTRUMENTS IS MUCH SMALLER THAN THE RANGING ERRORS INTRODUCED BY DELAYS THROUGH THE IONOSPHERE AND THE ATMOSPHERE 4HE DELAYS IMPOSED BY THE IONOSPHERE ARE A FUNCTION OF FREQUENCY )N PRACTICE  THESE CAN BE ESTI 
 Insofar as the primary operation of the equipment is concerned, the transmitted signal may be considered an unmodulated CW, although small-amplitude amplitude modulation (AM) or small-deviation frequency modulation (FM) is sometimes employed to provide coding or to give a rough indication of range. The modulation frequency is chosen to lie above the doppler band of interest, and the circuitry is designed to degrade the basic noise performance as little as possible. A spectrum-spreading problem is also posed by conical scan. 
 The maximal-length sequences are of particular interest. They are the maximum-length sequences that can be obtained from linear-feedback shift-register generators. They have a structure similar to random sequences and therefore possess desirable autocorrelation functions. 
 #(),, .ATIONAL 2ADAR &ACILITY v  * !TMOS /CEAN  4ECH    PP n    - 4HOMSON  h4HE ASTROMESH DEPLOYABLE REFLECTOR v  )%%%  3YMP  !NTENNAS  AND  0ROPAG   PP n    - 4HOMSON  h!STROMESH $EPLOYABLE 2EFLECTORS FOR +U AND +A 
 The ship radar uses asearch setand aheight finder whose antennas occupy thesame pedestal. The search sethas abeamwidth inazimuth of1.5° and elevation coverage upto15°. The height finder antenna is 15fthigh by5ftwide, fedat8.9-cm wavelength byaspecial feed (Sec. 
 Trig, Triggerin += p~llr.,,.. %llillr’~ 4 . (I2L.ti---Wtic +==== FIG. 
 An adaptive ISAR imaging of maneuvering objects based on a modiﬁed Fourier transform and distributed ISAR sub-image fusion of a nonuniform rotating target based on matching Fourier transform are 105. Sensors 2019 ,19, 3344 discussed in [ 13,14]. To mitigate blurring and defocusing e ﬀects induced by maneuvering targets on the process of ISAR imaging an original method based on modiﬁed chirp Fourier transform is suggested in [15]. 
 RANGE SHIPBOARD AIR 
 where r = the distance from the feed to the reflecting surface and k = 2ir/X = the wavenumber. Each reflector grid region represents the reflection of a small uniformly illu- minated section. It has a gain factor and also a direction of reflection, which fol- lows Snell's law. 
 The radar detection problem is a binary hypothesis- testing problem in which H0 denotes the hypothesis that no target is present and H1 is the hypothesis that the target is present. While several criteria (i.e., definitions of optimality) can be used to solve this problem, the most appropriate for radar is the Neyman-Pearson.3 This criterion maximizes the probability of detection PD for a given probability of false alarm Pfa by comparing the likelihood ratio L [defined by Eq. (8.1)] to an appropriate threshold T which determines the Pfa. 
 Itisassumed inthisanalysis thatthelengthsofthedirectandthereflected pathsarealmost (butnotquite)equalsothattheamplitudes ofthetwosignalsareapproximately thesame provided thereisnolosssufferedonreflection. Hence,iftheamplitudes ofthetwowavesdiffer fromoneanother, itisassumed tobeduetoasurface-reflection coefficient lessthanunity. Although thetwopathsarecomparable inlength,theyarenotexactlyequal.Anydifference in therelativephasebetween thedirectandthereflected ~avescanbeattributed tothedifference inthepathlengthandthechangeinphasethatoccursonreflection. 
 Q) D :oJ a Ea <lJ> a Q)cr o 1m 2/'!1 FrequencyI IIFigure3.15Spectrum ofthedifference­ frequency signalobtained froman FM-CW radarsinusoidally modulated atafrequency fmwhenthetarget motionproduces adoppler frequency shift.r.,.(AfterSaunders,9 IRETrans.). 90 INTRODUCTION TO RADAR SYSTEMS  Figure 3.16 Plot ol Bessel funcrions  of order 0, 1, 2, and 3; D =  (A/'/'/,) sin 2?L!Rolc.  The technique of using higher-order Bessel functions has been applied to the type of  doppler-navigation radar discussed in the next section. 
 That is, the receiver may not be  tuned to the correct frequency. To circumvent this potential loss of signal, a bank of contig­ uous matched filters must be used to cover the range of expected doppler-frequency shifts. It  is possible, however, with a suitable transmitted waveform to employ a single matched filter  that will accept doppler-shifted echoes with minimum degradation. 
 The prf must be high enough to avoid  angle ambiguities and image-foldover that results from grating lobes produced when the  spacing between the elements of the synthetic array is too large. These two conflicting require-  ments on the prf of a SAR mean that the resolution and the coverage (swath) cannot be  selected independently.  To avoid grating lobes in a phased-array antenna of isotropic radiating elements (with  the main beam perpendicular to the aperture), the element spacing must be less than the  wavelength A (Sec. 
 A jammer  which radiates over a wide band of frequencies is called a barmge Jammer.  To take full advantage of frequency agility, the. radar should employ a prelook receh•i1r to  examine the jammer's spectrum and 'Select a frequency for the next radar transmission where  the noise is a minimum. 
 J. Maxum, G. M. 
 In spite of these  limitations, the HF region of the spectrum is of special interest for radar because of its unique  property of allowing propagation to long distances beyond the curvature of the earth by  means of refraction from the ionosphere. A single refraction allows radar ranges to be ex-  tended to almost 4000 krn. The targets of interest to HF over-the-horizon (OTH) radar are the  OTHER RADAR TOPICS529 / IaI~~\ X""'fJ:v\ I , I I ~-----_ ...--..--------',; w,---'----- Direction ofradar Figure14.7InverseSAR,orrange-doppler imaging, ofarotating ohject. 
 During WWII losses of Coastal-Command-controlled aircraft [ 5] were 741 on anti-U-boat operations, 885 on anti-shipping operations and 443 on other oper- ations, resulting in total losses of 2069 aircraft. A total of 5863 aircrew were killed inbattle and a further 2261 in ﬂying accidents. By overcoming the U-boat threat the aircraft and crews of Coastal Command had made a decisive contribution to the outcome of the war and the supportingtechnology, including ASV radar as described in this book, played a very signi ﬁcant part. 
 ATED WITH FAIR WEATHER AND WITH INCREASED OCCURRENCE OF SURFACE 
 AMPLITUDE WAVEFORM )T ALSO SHOULD BE AN ADVANTAGE FOR RADAR APPLICATIONS THAT REQUIRE SHAPED WAVEFORMS AT FREQUENCIES UP TO  -(Z  WHEN IT IS REQUIRED TO REDUCE THE FAR 
 PULSE FEEDFORWARD CANCELER  INDE 
 Thus, itis possible tokeep Gand B(the load) fixed, and study theeffect ofHand 1 onP,k,and Vwiththeassurance that thenature oftheresults will not begreatly altered bychanges inGand B.Conversely, Hand 1may be fixed and the effect ofGand BonP,A,and Vobserved. Asaresult of this situation, itiscustomary topresent theoperating data ontwo graphs. One iscalled the “performance chart,” and shows the relationship between H,I,V,P,and Xforconstant load; the other iscalled a“Rieke diagram,” and shows the relationships between G,B,P,k,and Vfor constant Iand H. 
 36-42, August,  1972.  3 I. Anonymous: Phased-1\rray Power Amplifier, Microwave J., vol. 
 BASED DUCTS TEND  &)'52%  3URFACE DUCT 
 Itscathode islarger than isusual for. SEC.11°12] ILL US’TRA TIVE EXAMPLES OF R-F HEADS 427 AFC TR -K--%4W’ ATR– :e wu cavny &h&r‘A‘“’’O’’’’’””’\BeaconAFCcrystal e“agne’ronFIG.11.29.—R-f system,. 428 RFCOMPONENTS [SEC. 
 A given in-phase and quadrature measurement does not give a  unique value of elevation angle since the plot of the complex angle shows multiple, overlap­ ping turns of a spiral with increasing target altitude. The ambiguities can be res_olved with  frequency diversity or by continuous tracking over an interval long enough w recognize the  ambiguous spirals. In one simulation of the technique it was found that tracking over a  smooth surface can be improved by at least a factor of two, but over rough surfaces the  improvement was marginal.61  Thus there exist a number of possible techniques for reducing the angle errors found when  tracking a target at low angle. 
 There are losses of the dielectric (e.g. water, where the penetrating  waves quickly dissipate), whereby this attenuation due to losses is proportional to  the frequency  and the loss angle of the material.   When a wave from free space, as in Figure 2.3, encounters a infinitely extended dielectric surface  with relative permittivity εr, then a coherent wave is dispersed in the entire, which has varying  characteristics in the two subsections and whose electrical field lines experience a break when crossing the interface, if the field line does not arise perpendicularly. 
 The periodic train of pulses, however,.does not suffer this limitation. The time-delay error is  determined by the pulse width -r as before, but the frequency accuracy is determined by the  total duration of the pulse train. Thus the time-and 'frequency-measurement ae,curacies may  be made independent of one another. 
 MTI and pulse doppler radars are  particularly susceptible to any such internal oscillators that are not coherent, i.e., that  do not have the same phase for each pulse transmission. The effect of the spurious  signal is then different for each return, and the ability to reject clutter is degraded.  FIGURE 6.7  Phase noise aliasing in a pulse doppler systemL(f) Frequency0fPRF −fPRF2fPRF 3fPRF −3fPRF−2fPRFPhase Noise after Downconversion  and Receiver Filtering Phase Noise Shifted kfPRF FIGURE 6.8  Sampled phase noise spectrum due to phase noise aliasingFolded Phase Noise  Spectrum Doppler FrequencyfPRF 0Phase Noise (dBc/Hz)L(f)^ ch06.indd   19 12/17/07   2:03:20 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Arlington, Va.•Apr.21·23.1975. pp.312-317. 2X.Shrader. 
 Any use is subject to the Terms of Use as given at the website. The Radar Transmitter. 10.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 The magnetic field in a gyrotron serves a different function from the magnetic field  in a slow-wave device. In the slow-wave device, the magnetic field keeps the electronic  beam collimated. 
 1613a. has advantages over the other schemes. Inthe first place, the signals are added atintermediate Modulator — Transmitter TR L MixerStableIwal— — oscillatorMixer I I f ! (a) I 1 / Power ~ amplifierTR 1=I IEchosignals 1* MixerStablelocal— MixerReference oscillator signal II If transmitterModulator LO Mixer t Coherent I.f Receiver oscillator L t (b) FIG. 
 The antenna not only  concentrates the energy on transmit and collects the echo energy on receive, but it also  acts as a spatial filter to provide angle resolution and other capabilities. ‡  In radar, range  is the term generally used to mean distance from the radar to the target. Range is also used here in  some of its other dictionary definitions. 
 ZERO THROUGH  n   WITH  THE SPREADING FUNCTION DEPENDING ON MANY VARIABLES  INCLUDING THE RECENT SURFACE  WIND HISTORY (& RADAR HAS SUFFICIENT SENSITIVITY TO MEASURE THE RELATIVE AMPLITUDE OF  THE WAVES RUNNING AGAINST THE WIND  EVEN THOUGH THEY MAY HAVE A POWER SPECTRAL DENSITY AND HENCE AN 2#3  SEVERAL ORDERS OF MAGNITUDE BELOW THOSE RUNNING WITH THE WIND 4HESE UPWIND 
 LENGTH SEQUENCES HAVE SOME DESIRABLE AUTOCORRELATION CHAR 
 The loss result- ing from use of only the central line is essentially the duty cycle dt. For a peak transmitted power P19 the average power in the central line is Pt(dt)2, compared with the average power of the transmitted waveform of Pt(dt). A low duty cycle (less than 10 percent) can also be used, but for this case the central-line power loss becomes prohibitive. 
  
 Woods, “A radar ocean imaging model for small to moderate  incidence angles,” Int. J. Remote Sensing , vol. 
 P. Howson: Image-Cancelling Mixers at 2 GHz, Electronic  Letters, vol. 10, no. 
 The channel  tlrrlir~g mechanism avoids the problem of the frequency tracking of the resonant cavities by  preti~ning the cavities (generally at the factory); and the tuning informaticn is stored mechan-  ically within the tuner mechanism. Thus when a particular frequency channel is desired, the  tuner mechanism provides the correct tuner position for each cavity to achieve the desired  klystron frequency response. The klystron differs from other tubes in that the t\igher the peak  power, the greater can be its  Other properties. 
 This is called the n trrodr. The presence of N cavities in the magnetron results  in N/2 possible rnodes of operation. Each of these N/2 modes corresponds to a different RF  field co~lfiguration riladc up of a standing wave of charge. 
 Y GRID  & GRID  IN THE APERTURE PLANE IS  EASILY DETERMINED FROM THE FEED AND SPACE TAPERING  &X Y&X Y ZF R&X Y Z XGRID FEEDFEED                Y F    WHERE &FEED IS THE FEED RADIATION PATTERN &OR THIS CASE  WITH THE FEED AT THE FOCAL POINT   THE TOTAL DISTANCE TRAVELED FROM THE FEED TO THE REFLECTOR AND BACK TO THE APERTURE 
 ASPECT RATIO FEATURES LIKE PIPES  WIRES  AND FRACTURES &)'52%  ,OSSES FOR '02 SIGNAL VERSUS RANGE #OURTESY )%%   !                        #  
 In statistics texts, 2tn is the number of degrees of  freedom, and is an integer. However, when applied to target cross-sect~on models, 2111 is not  required to be an integer. Instead, m can be any positive, real number. 
 34!4% 42!.3-)44%23   ££°ÓÎ L 0HASE ERRORS IN CASCADED STAGES SIMPLY ADD (OWEVER  IT MAY ALSO BE POSSIBLE TO  ARRANGE THEM TO CANCEL BY PROPER PHASING OF POWER SUPPLY RIPPLES FOR DIFFERENT  STAGES 3IMILARLY  IN A STAGE WITH  . MODULES IN PARALLEL  EACH WITH ITS OWN HIGH 
 F. George: Detection of Targets in Non-Gaussian Sea Clutter, IEEE Trans.,  vol. AES-6, pp. 
 C.: " Microwave Scanning Antennas, Volume 11," Academic Press, New York, 1966.  13. Hines, J. 
 TO 
 Natl.Con(Proc.Aeronaut. Electronics (Dayton. Ohio).rr.133-144. 
 4(% 
 TechnoL, vol. 4, p. 518, 1987. 
 Solid sheet surfaces may be of either aluminum or steel. 15· 16 Steel is a popular choice,  particularly where weight is not a controlling factor. It is cheap and strong but is relatively  difficult to form. 
 DUSK ORBIT   
 J. Anderson, “Receiver array calibration  using disparate sources,”  IEEE Trans. Ant. 
 During this time, Task 4’s require - ments would be violated. Tasks 3 and 4, as defined, are incompatible. Task 5 (remote sensing of ocean conditions) would have a much lower priority as  it deals with slowly varying phenomena, so it would need only occasional revisiting. 
 To  make the most efficient use of transmit power and optimize  range resolution, most radars modulate pulses using a variety  of techniques  (see Figure 5).   Figure 5. Common Pulse Modulations – constant CW (top),  Linear FM (middle), Phase -Shift Keying (bottom)   Linear FM Chirps   The simplest  pulse modulation scheme is the  linear FM (LFM)  chirp. 
 The simple method of providing TR (transmit-receive) switching can be obtained  by combining two halves of a subarray with a four-port hybrid junction. The transmit - ter input into one port energizes both halves of the aperture, for example, in phase.  The receiver, connected to the remaining port, then requires that the phase shifters of  half the aperture give an additional phase shift of p  during the receiving period. 
 Against a conically scanning tracking radar, an inverse-gain re- peater jammer has the effect of causing positive feedback, which pushes the tracking-radar antenna away from the target rather than toward the target. Inverse-gain jamming and RGPO are combined in many cases to counter conical- scan tracking radars.12 A different form of DECM used against the main beam of surveillance radar attempts to cover the target's skin return with a wide pulse in order to confuse the radar's signal-processing circuitry into suppressing the actual target return. In the deployment-employment of ECM, five classes can be singled out.12 In the standoff jammer (SOJ) case, the jamming platform remains close to but out- side the lethal range of enemy weapon systems and jams these systems to protect the attacking vehicles. 
 Since the IF amplifier signal includes both the feedthrough and the clutter while the video amplifier includes the clutter, the specific AGC implementation must consider the degree to which these large interfering signals shall be allowed to control the gain for the target signal while preventing saturation on the interference. To maintain linear receiver operation over the large dynamic range is a major design challenge. Unambiguous (Offset Video) Receiver. 
 Background noise data  used in conjunction with the backscatter data for the Excess Power analysis is col - lected using the same eight directional beams as the backscatter sounder . While there are a few significant gaps in these time series, they span two solar  cycles; further, integrity has been maintained by extensive vetting before entering  new data into the database. The unique advantage of this database is that the noise and  propagation data are recorded under identical ionospheric conditions, whereas com - bining independent clutter and noise statistical models such as IRI-2001 with CCIR  322-3 preserves no correlations, however strong they may be. 
 the cone-sphere can have very low backscatter energy. Suppose, for example, that the  projected area of the cone-sphere were 1 m2• The radar cross section of a sphere, with the same  projected area, at S band is about 30 dB greater. A corner reflector at S band, also of the same  projected area, has a radar cross section about 60 dB greater than the cone-sphere. 
 False-Alarm Control. In the presence of clutter, if fixed thresholds are used with the previously discussed integrators, an enormous number of detections will occur and will saturate and disrupt the tracking computer associated with the radar system. Four important facts should be noted: • A tracking system should be associated with the automatic detection system (the only exception is when one displays multiple scans of detections). 
 By systematically surveying  the area in a regular grid pattern, a radar image of the ground can be built up. GPR  images are displayed either as two-dimensional representations, using horizontal   (x or y) and depth ( z) axes or a horizontal plane representation ( x, y) at a given depth  (z) or as a three-dimensional reconstruction. GPR data may be classified as A-scan,  B-scan, or C-scan depending on the plane of image (note these are not the same as  conventional radar A, B, and C scans). 
 D. DeRoo et al., “MMW scattering characteristics of terrain at near-grazing incidence,” IEEE  Trans. on Aerosp. 
 Curves exist".37 for various values of tiits per scan, 11, that give the signal-to-noise ratio  per pulse as a function of P, and rt,. Tile signal-to-noise ratio per pulse can be used in the form  of tlie radar equation as given by Eq. (2.32). 
 When thereflector ismade more negative, thebunch arrives atthecavity IIntheolder two-cavity klystrons, where thebunching takes place inafield-free space, thebunch forms about theelectron that passes through thefirstcavity asthe field ischanging from deceleration toacceleration.. 416 R-F COMPONENTS [SEC. 11.8 early, hurries the oscillation and increases the frequency. 
 These holes in the coverage can  seriously affect airborne surveillance radars as well as ground-based and ship-borne radars.  The extended ranges during ducting conditions mean that ground clutter is likely to be present  at longer ranges. This can put a severe burden on some MTI radars that are designed on the  assumption that clutter will not appear beyond a certain range. 
 Eikenberg: Ferroelectric Phase Shifters for VHF and UHF, IRE Tram,  ~ol. MTT- 10, pp. 536-548, November, 1962. 
 Atsome point inthereceiver, ahead ofanysaturation orlimiting, thesignals aresplit into two channels, inone ofwhich they areamplified much more than intheother. Ifthe signals arenot already invideo form, each channel includes adetector. Inany case, each contains alimiter, the one inthe low-gain channel being setatapproximately twice thelevel oftheother. 
 ,IMIT ON -4) )MPROVEMENT &ACTOR )  D"              .   -4) 2!$!2  Ó°Çx 0ULSE #OMPRESSION #ONSIDERATIONSo  7HEN AN -4) SYSTEM IS USED WITH PULSE  COMPRESSION  THE SYSTEM TARGET DETECTION CAPABILITY IN CLUTTER MAY BE AS GOOD AS A  SYSTEM TRANSMITTING THE EQUIVALENT SHORT PULSE  OR THE PERFORMANCE MAY BE NO BETTER THAN A SYSTEM TRANSMITTING THE SAME LENGTH #7 PULSE 4HE KIND OF CLUTTER ENVIRONMENT  THE SYSTEM INSTABILITIES  AND THE SIGNAL PROCESSING UTILIZED DETERMINE WHERE THE SYSTEM PERFORMANCE WILL FALL BETWEEN THE ABOVE TWO EXTREMES 5NLESS PROVISION IS INCORPO 
 70. D. J. 
 ..  scan. Because of this property, the Palmer scan is sometimes used with conical-scan tracking  radars which must operate with a search as well as a track mode since the same mechanisms  used to produce conical scanning can also be used for Palmer scanr.ing.60 Some conical-scan  tracking radars increase the squint angle during search in order to reduce the time required to  scan a given volume. 
  ON %3!S  %.6)3!4  ARE OF SECOND PRIORITY WITH RESPECT TO THE OTHER INSTRUMENTS ON THEIR RESPECTIVE SPACECRAFT 4HEIR SUN 
 Ê 
 TIVELY COMBINED WITH A LOWER MICROWAVE BAND AS DESCRIBED IN 3ECTION  TO TAKE ADVANTAGE OF THE COMPLEMENTARY FEATURES OF BOTH BANDS 4ARGET !NGLE AND 2ANGE 3CINTILLATION 'LINT  2EDUCTION  4ARGET 
  
  D"  CAN BE READILY REALIZED WITH PHASED 
 IEEE1975International RadarConference, pp.283-287. Apr.21-23.1975.IEEEPublication 75CHO938-1AES. 24.Cook.C.E.,andM.Bernfeld: "RadarSignals." Academic Press,NewYork,1967. 
 Here, it is necessary only to show the postdetection  spectrum of the preceding example and to consider the number of independently  fading samples per second. Figure 16.10 shows the spectrum before and after  square-law detection. For square-law detection, the post-detection spectrum is the  self-convolution of the predetection spectrum. 
 N FIG. 3,28.—The Kanto plain north ofTokyo. Wavelength =3.2cm,3“beam, altitude 10,000 ft,radius 28nautical mi. 
      .   2!$!2 $)')4!, 3)'.!, 02/#%33).'   Óx°Óx THAT STAGE P I FROM THE TABLE  TO THE PREVIOUS VALUE OF  E  )F E     P I IS ADDED TO  E  /THERWISE   P I IS SUBTRACTED FROM  E )N EACH STAGE  THE 1 OR )  INPUT IS DIVIDED BY A FAC 
 The receiver protector might use solid-state diodes for an  all solid-state configuration,48 or it might be a passive TR-limiter consisting of a radioactive  primed TR-tube followed by a diode limiter.49·50 The ferrite circulator with receiver protector  is attractive for radar applications because of its long life, wide bandwidth, and compact  design.  Other duplexer considerations. The duplexers described above using passive receiver protec­ tors have recovery times from a fraction of a microsecond to several tens of microseconds. 
 STATE ISOLATION OF THE DEVICE 4HIS CAPACITANCE DEPENDS LARGELY ON THE SOURCE 
 There are  several methods by which angle-error information might be obtained with only a single pulse.  More than one antenna beam is used simultaneously in these methods, in contrast to the  conical-scan or lobe-switching tracker, which utilizes one antenna beam on a time-shared  basis. The angle of arrival of the echo signal may be determined in a single-pulse system by  measuring the relative phase or the relative amplitude of the echo pulse received in each beam. 
 The threshold level mustbe low if weak signals are to be detected, but it cannot be so  low that noise peaks cross the threshold and give a false indication of the presence of targets.  The voltage envelope :of. Fig. 
 E. K., and D. E. 
 30, no. 4, pp. 1130–1137,  October 1994. 
 32,   pp. 450-456, 1996. 49. 
 The applicability of DPCA or step-scan compen - sation in the latter case is dependent on the particular system parameters. FIGURE 3.15  MTI improvement factor for a  step-scan compensation of a single-delay canceler  as a function of the number of hits per beamwidth.  The antenna pattern is (sin x)/x. 
 URSI Commission F Symposium , Ispra, Italy, 2005. 124. E. 
 5.1 the amplitude -asJ  fluctuations are assumed to be larger than servo noise. If not, the improvement of rnonopulse  tracking over conical scan will be negligible. In general, the tracking accuracy deteriorates at  ry\ both short and long target ranges, with the best tracking occurring at some intermediate range. 
 FICIENT #   J$ TO PRODUCE !# n "$     J!$   "#  IN ORDER TO EFFECT THE PHASE SHIFT  4HIS OPERATION REQUIRES FOUR MULTIPLIERS AND TWO ADDERS !FTER SOME MANIPULATION  THE FOLLOWING CAN BE SHOWN  )    !# n "$    $! n "    !# n $    1    !$   "#    #!   "  n !# n $   .OTING THAT THE FINAL TERM IS THE SAME IN BOTH EQUATIONS  WE SEE THAT THIS COMPLEX  MULTIPLIER CAN BE IMPLEMENTED WITH ONLY THREE REAL MULTIPLIERS AND FIVE REAL ADDS 4HIS CAN BE IMPORTANT IF REAL MULTIPLIERS ARE AT A PREMIUM &IGURE  SHOWS A BLOCK DIAGRAM OF THIS ARCHITECTURE #/2$)# 0ROCESSOR  !N EFFICIENT AND VERSATILE ALGORITHM THAT CAN IMPLEMENT A  PHASE SHIFT WITHOUT USING MULTIPLIERS IS THE  #/ORDINATE  2OTATION  $)GITAL #OMPUTER  #/2$)#  FUNCTION  FIRST DESCRIBED BY 6OLDER  IN  4HE #/2$)# CAN IMPLEMENT  &)'52%   3TANDARD COMPLEX MULTIPLY  
 1W.L.Myers, “Weight Analysis ofAirborne Radar Sets,” RLRsport No.450, Jan. 1,1945.. 616 EXAMPLES OFRADAR SYSTEM DESIGN [SEC.15.14 15.14. 
 Proc.IRE.vol.25.pp.630-643. May.1937. 75.Block.1\.,R.C.Medhurst, andS.D.Pool:Superdirectivity, Proc.IRE,vol.48.p.1164,June.1960. 
 DIMENSIONAL AIR 
 D" BEAMWIDTH OF THE RADAR (OWEVER  A LARGE TARGET SUCH AS AN AIRCRAFT FORMATION MAY EXTEND BEYOND THE LINEAR ANGLE 
 87  11.2 Fundamentals of Radar polarimetry ............................................................................... 89  11.2.1 Polarization ............................................................................................................. 89  11.2.2 Polarization Scattering Matrix ................................................................................ 
 β = 4.8 β = 6.5 β = 9.7 70 dB(a) 1–2 (b) 6–7 (c) 18–20Wind (mph)LCE (7.0 km, 166 °) Forest (c) Windy Noise (b) Breezy (a) Light Air20 0 −20 −40 −60Ptot (dB) −3 −2 −1 0 1 2 3 Doppler Velocity v (m/s) FIGURE 2.13 Measured spectra of clutter from forest. Several wind  speeds and an estimated value of b  have been added. ( after J.B. 
 , ,I  The log-FTC receiver described in Sec. 13.8 has CFAR properties when the background  has a Rayleigh probability density function. The FTC, or fast time-constant, acts as a differen-  tiating circuit, or high-pass filter, to remove the mean value of the clutter or noise. 
 70. Ref. 37, vol. 
 Óä°Î{  2!$!2 (!.$"//+  PREDOMINANTLY TO WAVES WHOSE VELOCITIES ARE FAIRLY CLOSELY MATCHED TO THE WIND VELOC 
 Keywords: oceanic eddies; shear-wave-generated eddies; burgers-Rott vortex model; SAR image simulation 1. Introduction As an important part of ocean dynamics, the formation, motion, and dissipation of eddies are signiﬁcant research issues for oceanographers. The movement of eddies will agitate seawater and expand the scope of biological organisms, thus affecting the distribution of organics and the transportation of heat and salt in the ocean. 
 The double  curvature reflector is designed to provide both the desired shaping of the beam in one plane  and focusing in transverse planes.1•94-96 The surface is formed by the envelope of a system of  paraboloids whose axes all lie in the plane of the shaped beam, but at varying angles of  inclination to each other and to a fixed line.  The antenna of the S-band Airport Surveillance Radar (ASR) or the AN{f PN-19 landing  system is shown in Fig. 7.25. 
 ARY HOT CLUTTER CANCELLATIONnPART  &UNDAMENTALS AND SUPERVISED TRAINING APPLICATIONS v  )%%%  4RANS  !%3n  NO   PP n    9 ) !BRAMOVICH  . 3PENCER  AND 3 * !NDERSON  h3TOCHASTIC CONSTRAINTS METHOD IN NON   STATIONARY HOT CLUTTER CANCELLATIONnPART  5NSUPERVISED TRAINING APPLICATIONS v  )%%% 4RANS    VOL !%3n  NO   PP n    ' ! &ABRIZIO  !  " 'ERSHMAN  AND - $ 4URLEY  h2OBUST ADAPTIVE BEAMFORMING FOR (&  SURFACE WAVE OVER 
 -Ê"Ê- 
 HOUSE PROGRAM  273 ORIGINATES FROM THE MODELING AND SIMULATION ACTIVITIES CARRIED OUT FOR PREDICTION OF RADAR PERFORMANCE IN SEVERAL SCENARIOS /NE MAIN OBJECTIVE OF 273 IS TO PROVIDE THE RADAR ANALYST OR SYSTEM DESIGNER WITH A FRIENDLY BUT COMPREHENSIVE TOOLKIT FOR PREDICTION OF RADAR PERFORMANCE BASED ON WELL RECOGNIZED  FLEXIBLE  AND DOCUMENTED MATHEMATICAL MODELS ! BROAD RANGE OF RADAR TYPES BI 
 From that  results a compressed pulse shape of sin x/x.  If one identifies the frequency pass with B and  the pulse duration with τ, then the amplitude of the pulse is proportional to  τBand the width  to 2/B.  Under these conditions the Fourier transform of the compressed pulse of the entrance  pulse has the form:  € sin(πBt) πBt (8.17)  The overshoot of Function (8.17) would interfere with the video detection. 
 +β ·α :LCUT 3 2 1   Figure 12.4  Principle of the CAOS -CFAR circuit.   The CAOS- CFAR comprises essentially a shift register with “A” sub -registers, each contai n- ing L storage cells. Each sub- register has its own adder. 
   .OVEMBER   2 % 7ILLEY  h3PACE TAPERING OF LINEAR AND PLANAR ARRAYS v  )2% 4RANS  VOL !0 
 12•If multiple signal sources of the sa me frequency are present, or multiple  paths exist between a radar and target , then the total signal at a location  is the sum (superposition principle). •The result is interference : constructive interference occurs if the waves  add; destructive interference occurs if the waves cancel. •Example: ground bounce multi-path can be misinterpreted as multiple  targets.Superposition of Waves th rh rdtdGrazing Angle,ψAirborne Radar Target. 
 STEERED  SYSTEMS 9AW STEERING IMPOSES  NEGLIGIBLE ADDITIONAL  DEMANDS ON THE SPACECRAFT ATTITUDE CONTROL SYSTEM  SINCE IT REQUIRES MANEUVERS OF ONLY on OVER EACH ORBITAL PERIOD .OTE THAT A 3!2 LOOKS DOWN AS WELL AS TO THE SIDE  SO THAT VERTICAL VELOCITY COMPONENTS IN THE SATELLITES ORBIT ALSO LEAD TO DOPPLER SHIFTS IN THE DATA )N PRINCIPLE  A DOPPLER SHIFT FROM A VERTICAL VELOCITY COMPONENT ALSO COULD BE OFFSET BY ATTITUDE ADJUSTMENTS OF THE SPACECRAFT  ALTHOUGH THIS STRATEGY IS NOT IN GENERAL PRACTICE $OPPLER CENTROID ESTIMATION IS A CENTRAL FUNCTION IMPLEMENTED IN ALL PROCESS 
 Included in this discus- sion are various noncoherent integrators that provide target enhancement, thresholding techniques for reducing false alarms and target suppression, and al- gorithms for estimating target position and resolving targets. Then, an overview of the entire tracking system is given, followed by a discussion of its various com- ponents such as tracking filter, maneuver-following logic, track initiation, and correlation logic. Next, multiscan approaches to automatic tracking such as max- imum likelihood are discussed. 
 ÓÓ°ÓÈ  2!$!2 (!.$"//+  2ACONS 4HE )NTERNATIONAL !SSOCIATION OF -ARINE !IDS TO .AVIGATION AND  ,IGHTHOUSE !UTHORITIES )!,!  SETS THE PERFORMANCE STANDARDS FOR RACONS 4HESE  INCORPORATE THE TECHNICAL CHARACTERISTICS SET OUT IN A SPECIFIC )45 
 A. Merritt, K. P. 
 72.2 PARAMETERSAFFECTINGGROUND RETURN Radar return depends upon a combination of system parameters and ground parameters: Radar system parameters [Eqs. (12.1) and (12.2a and b)] Wavelength Power Illuminated area Direction of illumination (both azimuth and elevation) Polarization Ground parameters Complex permittivity (conductivity and permittivity) Roughness of surface Inhomogeneity of subsurface or cover to depth where attenuation reduces wave to negligible amplitude Different wavelengths are sensitive to different elements on the surface. One of the earliest known and most striking directional effects is the cardinal-point effect in return from cities: Radars looking in directions aligned with primary street grids observe stronger regular returns than radars at other angles. 
  
 The digital  receiver outputs are passed through PRI delays to yield temporally displaced data  samples. A full complement of elements and time-delayed signals are sampled and  used to generate the adaptive weights. Various algorithms are possible to generate the  estimate of the adaptive weights from Eq. 
 (a) Echo pulse; (h) early-late range  gates; (c) di!Terence signal between  early and late range gates.  which the gates must be repositioned by a feedback-control system. When the error signal is  zero. 
 MANCE IN A COMPLEX  HETEROGENEOUS CLUTTER AND JAMMING INTERFERENCE ENVIRONMENT $OPPLER FILTERING IS PERFORMED AFTER DIGITAL BEAMFORMING /THER FUNCTIONS DISCUSSED IN THIS CHAPTER ARE NOT REQUIRED FOR THIS RADAR APPLICATION  BECAUSE THEY DO NOT LIMIT PERFORMANCE %XAMPLES INCLUDE SCANNING MOTION COMPENSA 
 Although thesuperregenerative, crystalvideo,andtunedradiofrequency (TRF)receivers havebeenemployed inradarsystems, thesuperheterodyne hasseenalmostexolusive applica­ tionbecause ofitsgoodsensitivity, highgain,selectivity, andreliability. Nootherreceiver type hasbeencompetitive tothesuperheterodyne. Asimpleblockdiagram ofaradarsuperheter­ odynereceiver wasshowninFig.1.2.Therearemanyfactorsthatcnterintothedesignof radarreceivers; however, onlythereceiver noise-figure andthereceiver front-end, asthey determine receiver sensitivity, willbediscussed here. 
 However, there are very few radar applications which approximate  free-space conditions. In most cases of practical interest, the earth's surface and the medium in  which radar waves propagate can have a significant effect on radar performance. In-some  instances the propagation factors might be important enough to overshadow all other factors  that contribute to abnormal radar performance. 
 251–257. 31. M. 
 T(ρ⊥) is the ITF which includes both the phase and amplitude ﬂuctuations. The upward and downward ITF are the same since the symmetric propagation history. Therefore, the two-way ITF is calculated by squaring T(ρ⊥). 
 Hylas: Dome Radar-A New Phased Array System.  Record of rhe IEEE 197.5 Irrrernational Radar Conference, pp. 349-353, Apr. 
 It has also been considered for use in a low-signal  density environment when the criterion is that either no signal is present or one signal of fixed  and specified level is present and equally likely to be in any range interval. 38•39  The term sequential detection is sometimes used synonymously with Sequential Observer.  Sequential detection has also been used to describe a two-step, or two-stage, detection process . 
 BASED PHASED 
 R.: A New Tactical Radar. Ordnance, vol. 49. 
 The filter sidelobes between 0.8 and 1.0  doppler provide the specified chaff rejection of 46 dB. A mirror image of this filter is  used for the third moving doppler filter. (The mirror-image filter has coefficients that  are complex conjugates of the original filter coefficients.) Figure 2.53 c shows the first filter designed for response at zero doppler. 
 Controlling the phase  discontinuity from the end of one sweep to the beginning of the next provides another  dimension in which the waveform properties can be optimized. Further generalization  of the FM-CW waveform is possible by relaxing the condition that the waveform be  periodic. This is a powerful tool for controlling range-ambiguous echoes, which can be  shifted about in the range-doppler plane to uncover previously obscured target echoes. 
 ÊÊ  "// 
 Familiarize with the different types of Radar Displays and their application in real time  scenario                                      . 
 138 HOW RADAR WORKS  known route. This one test was enough to convince the  scientists that it would be worth while building a  specially designed radar transmitter and receiver for  ground search.  Very soon it became obvious that this system could be  used to build up for the navigator on his radar screen a  map of the terrain, for there were sharp differences in  the responses from flat country and built-up towns, and  again between land and sea. 
 If this impedance changes, the noise tem- perature changes. Therefore, in principle, when a noise-temperature rating is quoted for a receiver, the source impedance should be specified, especially since the optimum (lowest) noise temperature does not necessarily occur when imped- ances are matched. However, when a receiver noise temperature is quoted with- out this impedance specification, it is presumable that the optimum source im- pedance is implied. 
 The overall  ch22.indd   26 12/17/07   3:02:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 
 Nevertheless, it is important to know and understand how propagation phenomena  can influence radar performance since it can be a major factor in determining how well a radar  performs-in a particular application.  44 1  441CHAPTER TWELVE PROPAGATION OFRADAR WAVES 12.1INTRODUCTION Thepropagation ofradarwavesisaffectedbytheearth'ssurfaceanditsatmosphere. Complete analysis orprediction ofradarperformance musttakeintoaccount propagation phenomena sincemostradarsdonotoperate in..freespace"aswasass-umed intheidealformulation of theradarequation inChaps.Iand2.Free-space radarperformance ismodified byJ£11llf:ri/lg ofelectromagnetic energyfromthesurfaceoftheearth, ~~tioll causedbyaninhomo­ geneous atmosphere, andlli,elllwt;O/l bythegasesconstituting theatmosphere. 
 15. Sensors 2019 ,19, 1701 3.3. Application and Consideration For many artiﬁcial objects, the SAR image is greatly affected by the azimuth angle. 
 (12.24«). Snow scatter depends strongly on the free-water content of the upper layer of snow; so scatter is much lower from the wet daytime snow (where solar melting has commenced) than for the dry nighttime snow. Hence, different models must be used for day and night; compare the day and night measurements shown in Fig. 
 4, p. 237, 1922.  4. 
 CNN Models A CNN is composed of an input layer, an output layer, and multiple hidden layers. The hidden layers can be convolutional layers, pooling layers, activation layers, and fully connected layers [ 32,33]. The ﬁrst multilayer CNN is a simple convolutional network consisting of seven levels called LeNet-5 which was proposed by LeCun et al. 
 F. E. Nathanson, loc cit , Sec. 
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 (1936 –1941), BAC Washington (TNA AIR 20/1464). [4] Clements J 2001 Electronic Airborne Gold ﬁsh(UK: Paterchurch Publications) [5] A.S.V Equipment —Operational Use in Aircraft, RAF ﬁle S.3843,1940 —1941 (TNA AIR 2/5073) [6] Bowen E G 1987 Radar Days (London: Adam Hilger) [7] ASV Mk. II Equipment and Ancillaries, A.P. 
                    
 H. Soule, Jr., “Digital generation of wideband LFM waveforms,” IEEE Int.  Radar Conf. 
 : I'liased-Array Beam Steering by Multiplex Sampling, Proc. I EEE, vol. 56. 
 APERTURE R ADARS  KNOWN  AS /KEAN AND BY OTHER NAMES  !LMAZ WAS A VERY INTERESTING RADAR  IN THAT IT PROVIDED  UNIQUE 3 
         
 8, pp. 819-827, October, 1973. ·  23. 
 PHASE )  AND QUADRATURE 1  COMPONENTS SINCE BOTH THE AMPLITUDE AND THE PHASE OF THE SIGNAL STREAM ARE REQUIRED /NCE RESOLUTION AND SWATH ARE ESTAB 
 practically all of which was due to the strip transmission line used in the constr~ction.~' In a  lossless, passive antenna radiating rnultiple beams from a common aperture it has been shown8*  that tlie radiation pattern arid the crossover level of adjacent beams cannot be specified  indeperidently. With uniform illurnination, as iti the Butler array, the crossover level is 3.9 dB  helow the peak. 'l'liis is indepelident of the beam position, elerrient spacing, arid wavelength. 
 Ablock diagram isgiven in Fig. 17.18. The input signals areamplified and delivered push-pull to thedeviator byaphase splitter. 
 T. Sandwell, “Antarctic marine gravity field from high-density satellite altimetry,” Geophys.  J. 
 4. pt. I, pp. 
 MIMO array factor (in blue), obtained from the product of a transmitting array factor (in green) and a receiving array factor (in red). In a physical array, different sources of errors cause deviations from the ideal model; this fact limits the array performances, typically degrading the SideLobe Level ( SLL) of the point spread function. Assuming that, for a real system, the array factor Fcan be modeled as a random variable whose expectation value /angbracketleftF/angbracketrightis equal to the ideal one, then the SLL distribution can be read from the power of the statistical deviation δF=F−/angbracketleft F/angbracketright: SLL =/angbracketleft|δF|2/angbracketright. 
 Ionospheric Radio Propagation," National Bureau of Standards Monograph XO.  I\ pr. I. 
 374 INTRODUCTION TO RADAR SYSTEMS  L O 9 ~~~~~~~~_..._,...~~~-...---,----,-r ,--r -T T ] l ! I -·1  w - :::; 08  w .c u a o 1 - E  0 -t; 0.6  w 0.  "' t:' 0.5 - ~  L 0.4 - (U - >­u  C:  -~ 0 2 u  ....  C1)  11 0.1 --s,n91e-tuned (RLC)  resonant passband ...-Recton9ulor - shaped passband  1.0 2.0 3.0 40  Halt-power bondw'1dth times pulsewidth, Br J  50  Figure 10.2 Efficiency, relative to a matched filter, of a single-tuned resonant filter and a rectangular  shaped filter, when the input signal is a rectangular pulse of width r. 
 RAY OF A PHASED ARRAY ANTENNA  FORMING WHAT IS SOMETIMES CALLED AN  ACTIVE APERTURE  !PPLICATIONS RANGE FROM ULTRAHIGH FREQUENCY 5(&  FOR SURVEILLANCE TO 8 BAND AND ABOVE FOR AIRBORNE SYSTEMS ! TYPICAL MODULE IS SHOWN IN SIMPLE SCHE 
 Oscilloscope trace of an RF pulse train   Basic RF Pulsed Radar Signals   A simple pulse can be a single frequency that is turned on for  a short time and then off again. The s ignal travels from the  transmit antenna, reflects off of a target and returns to the  radar. The time it takes for the pulse to return represents the  range, or distance to the target. 
 Immedi-  ately this reaches a predetermined value ionization  occurs, the thyratron ‘strikes,’ and the condenser dis-  charges almost instantly through this low-resistance  path. It is worth noting that in most circuits the con-  denser does not discharge to zero volts, but to about 20 volts, which is a value so low compared with the “striking” voltage of the thyratron that the circuit does  give a true saw-tooth effect. During the following  charging period of the condenser the thyratron is vir-  tually a non-conducting path, and does not affect the linear charging curve we have striven to obtain. 
 Lorti and M. Balser, “Simulated performance of a tactical bistatic radar system,” IEEE  EASCON 77 Rec. Publ . 
 PUT SIGNAL 
 One is near the cathode and is at cathode potential. (In the so-called Unigrid,42  this grid is physically placed on the cathode but is properly passivated to prevent emission.)  The second grid is the control grid for the beam current. It is at a positive potential and is  located in the shadow of the 11rst grid. 
 The tracking-error information in beam-scanning tracking radars is a time fluc- tuation of the echo signal amplitude. Other sources of echo-signal-amplitude fluc- tuation such as target scintillation (Sec. 18.8) can cause false indications of track- ing error. 
 The advantage ofthe shorter wavelength ismain- tained throughout theinverse eighth-power region. Comparison ofEq. (3)with Eq. 
 A moving ship is not a static target during image formation, and the SAR imaging results are blurred and defocused [ 5–7]. It is necessary to refocus the defocused ship for ship recognition, and precise motion compensation becomes a key element of refocusing. The motion between the moving target and the radar contains translation and rotation motions [8,9]. 
 POWER  AMPLIFIER GENERATING A   LSEC MONOCHROMATIC PULSE HAVING PEAK POWER OF  K7  4HE ANTENNA IS A  M DIAMETER REFLECTOR OFFSET FED BY A QUASI 
 RUNNING  STABLE REFERENCE  SINUSOID ON WHICH THE SYSTEM SYNCHRONIZATION IS BASED 3YNCHRONIZER 4HE SYNCHRONIZER DISTRIBUTES PRECISELY TIMED STROBES AND CLOCKS FOR  THE VARIOUS COMPONENTS OF THE RADAR SYSTEM TO ENSURE THE TIME ALIGNMENT OF TRANSMIT  WAVEFORMS AND THE RECEPTION OF THEIR CORRESPONDING RETURNS 4HESE LOW 
 Henderson and A. Lewis (eds.), New York: Wiley Interscience, 1998,   pp. 9–130. 
 R., Jr.: Comments on the Design and Manufacture of Dual-Mode Reciprocal Latching  Ferrite Phase Shifters, lEEE Trans., val. MTT-22, pp. 593-601, June, 1974. 
 resolution cell and the sea state. An  example of sea clutter -statistics is shown :jn Fig. 13.5, which plots the probability that the  clutter will exceed the abscissa, rather than the probability density function. 
 262 INTRODUCTION TO RADAR SYSTEMS  7.8 EFFECT OF ERRORS ON RADIATION PATTERNS~~." I"'  Antenna-pattern synthesis techniques such as those discussed in Sec. 7.6 permit the a11tz11na  designer to compute the aperture illumination required to achieve a specified radiation  pattern. However, when the antenna is constructed, it is usually found that the experimentally  measured radiation pattern deviates from the theoretical one, especially in the region of the  sidelobes. 
 12.19 Effect of antenna beam width on the measured scattering coefficient as a func- tion of angle of incidence.THEORETICAL4.22° BEAMWIDTH8.44° BEAMWIDTH FIG. 12.20 Basic block diagram of an FM-CW scatterometer RF section.SWEEP-RATESIGNALSWEEPGENERATORSWEPTOSCILLATORDIRECTIONALCOUPLER TRANSMITTINGANTENNA SWEEP-RATECONTROLCENTER-FREQUENCYCONTROLISOLATOR IF (OR VIDEO)OUTPUTMATCHINGTRANSFORMER ISOLATOR RECEIVINGANTENNA . FIG. 
 Thus, a system concept is obtained that provides a clutter suppression capability that is limited only by the radar system stability, the dynamic range of the receiver-processor, and the spectrum width of the returns from clutter. The concept of a high-resolution dig- ital clutter map to suppress clutter residues is related to earlier efforts to con- struct analog area MTI systems using, for example, storage tubes.CLUTTER-FREE DOPPLER FILTERS LAND . In subsequent sections specific aspects of the design of an MTD system will be discussed. 
 For Track Acquisition, a search detection from VS would require a HRWS wave - form to obtain a range measurement. HRWS and Alert/Confirm waveforms are followed  by range gated high-PRF dwells using M-on-N ranging to achieve the necessary range  accuracy for single PRF track updates. The unambiguous HRWS range measurement of  the search detection is used to help resolve the range ambiguity. 
 34. Siegel, K. M.: Bistatic Radars and Forward Scattering, Proc. 
 24ofthis series, anattempt hasbeen made toshow directly the effect ofintegration intheA-scope. Here the camera has been substituted forthe eye, and the number of sweeps overlapping inone picture has been varied. Signals ofdifferent strength arepresent attwo positions ineach sweep and byreferring to theexplanation accompanying thefigure, thereader will beable totrace theimprovement indiscrimination from one picture tothe next. 
 The removal ofthe ground clutter isseen tobe complete. The photographs inFig. 16.2 were taken atBoston, Mass., where, because ofscreening byaring oflow hills, clutter does notextend appreciably beyond 10miles. 
 SUREMENTS DEVELOPMENT OF FUZZY LOGIC AND NEURO 
 G. Purves: Radar Imagery of Oil Slicks, I £EE Trans., vol. AES-9. 
 INTERFERENCE 
 The active methods described above can be used for the stabilization of power oscillators as well as for the stabilization of drivers. The measurement bridges are unchanged, but servo circuits must be altered to operate at high voltage and, in some cases, supply considerable power, since multicavity klystrons and crossed-field devices such as magnetrons and amplitrons can be modulated only through their high-voltage high-current supplies. Moreover, the fact that these are essentially "stiff" devices imposes more stringent requirements on the design of the servo. 
 CHIP OR MULTICHIP TRANSISTORS COM 
 This data was used to calculate  RV position and dynamics near the atmospheric pierce point or start of re-entry. The  system was projected to measure three-dimensional position and velocity with accura - cies better than 4 m and 0.1 m/s, respectively, throughout re-entry.43 Field tests showed that MMS range data combined with TRADEX ’s monostatic  range data in a trilateration net provided the most accurate estimate of exo-atmospheric  RV positions obtained by any of the range radars. MMS operations were concluded in  199356 after the metric accuracy of monostatic radars was improved.57 In the mid-1990s, a PBR using a cooperative FM broadcast transmitter in  the co-site region was developed by the University of Washington. 
 A. Skillman: Pulsedoppler Radar, chap. 19 of "Radar Handbook," M. 
 At a 300-Hz switching rate, 16 W of switching power was needed. The phase  shifter was 2.4 by 2.1 by 8.2 inches in size and weighed less than 1.5 Ib.  The relatively long time to switch the phase of the Reggia-Spencer phase shlfter from one  value to another has limited its application. 
 DATE BY HYDROGRAPHIC OFFICES THAT ISSUE UPDATE FILES ON A REGULAR BASIS !N )-/ 
 reduce thc angular error. The effective receiving area of the interferometer is usually less than  that of the conventional radar reflector antenna with which it is used. Thus, the range capa-  bility of the interferometer angle measurement might be less than that of the 2D radar. 
 BASED SYS 
 TO 
 Forexample, afterinitialcrossing ofthedetection threshold, theradarbeamcanbe returned tothesame direction soonerthanitwouldinnormalsearchinordertoverifythata targetwasindeeddetected andthatthethreshold crossing wasnotafalsealarmduetonoise. Thisl'er({icatioll plIlsecanbeofgreaterpowerand/oroflongerduration toincrease the probability ofdetection. Thetwo-step processof(I)initialdetection and(2)verification is sometimes calledseqllelltial detectioll. 
 Atthe end of 1940, theuseofmicrowaves forradar purposes seemed highly speculative, and theService laboratories quite properly feltittheir duty toconcentrate onradar techniques that had already been worked out successfully. During 1941, while the Navy was installing long-wave search radar and medium-wavelength fire-control radar onships ofthe fleet, and the Army was sending outSignal Aircraft Warning Battalions equipped with the SCR-270 and antiaircraft batteries with the SCR-268, not asingle item ofradar equipment based onthe new microwave techniques was delivered for operational use. However, development work atthe Radiation Laboratory had broadened farbeyond thetwo specific projects suggested bythe British Technical Mission, and microwave equipment was showing great promise formany wartime uses. 
 MENT  AND THE PHYSICAL PLACEMENT OF THE ELEMENTS &OR EXAMPLE  IF THE INSERTION AND DIFFERENTIAL PHASE VARIATIONS WHICH MAY OCCUR FROM PHASE SHIFTER TO PHASE SHIFTER  ARE KNOWN  THEY MAY BE TAKEN INTO ACCOUNT IN THE COMPUTATIONS +NOWN TEMPERATURE VARIATIONS ACROSS THE ARRAY THAT WOULD INDUCE PHASE ERRORS MAY BE COMPENSATED FOR &INALLY  MANY FEEDS EG  OPTICAL AND SERIES FEEDS  DO NOT PROVIDE EQUAL PHASE EXCITA 
 3.4 AIRBORNE DOPPLER  NAVIGATION^^ -s6  An important requirement of aircraft flight is for a self-contained navigation system capable of  operating anywhere over the surface of the earth under any conditions of visibility or weather.  It should provide the necessary data for piloting the aircraft from one position to another  without the need of navigation information transmitted to the aircraft from a grourd station  One method of obtaining a self-contained aircraft navigation system is based or the CW  doppler-radar principle. Doppler radar can provide the drift angle and trui spe d of the  aircraft relative to the earth. 
 J.: Doppler Radar, Proc. IRE, vol. 37, pp. 
 The spatial and temporal distributions of annual precipitation were extremely asymmetric, being three or four times higher in October and December. Extreme weather events, such as thunderstorms, wind, hail, and tornadoes occurred frequently, and disasters induced by rainstorms and typhoons were obvious. Under the combined inﬂuence of high trough and low vortex, continuous precipitation had occurred in the city from 27 August 2015. 
 MUM RANGE IS LOST /N THE OTHER HAND  IF THE 02&     K(Z  THE TIME BETWEEN PULSES  IS  MS  AND IT WOULD NOT BE POSSIBLE TO TOLERATE   MS OF DEAD TIME FOR THE SWITCHING  OF PHASE SHIFTERS !LL DIODE PHASE SHIFTERS ARE RECIPROCAL ALONG WITH CERTAIN TYPES OF FERRITE PHASE  SHIFTERS )T IS WORTH NOTING THAT  OWING TO LOSSES ASSOCIATED WITH THEIR MAGNETIC PROPER 
 SCALE 
 Moore, “The correlation function in Kirchoff’s method of solution of  scattering of waves from statistically rough surfaces,” J. Geophys. Res. 
 This gave rise toserious troubles because ofthe susceptibility ofthe regulator tovibration. Vibration ofthe carbon pile causes amplitude modulation or“jitter” of. 568 PRIME POWER SUPPLIES FORRADAR [SEC. 
 SPACE IMPEDANCE  %( VARIES AS COS  P FOR  SCANNING IN THE  % PLANE AND AS SEC  P  FOR SCANNING IN THE  ( PLANE 4HE IMPEDANCE OF  A MEDIUM IS THUS DEPENDENT UPON THE DIRECTION OF PROPAGATION  AND THE IMPEDANCE VARIATION OF A SCANNING APERTURE IS A NATURAL CONSEQUENCE OF THIS DEPENDENCE 4HE CONTINUOUS APERTURE APPEARS TO REPRESENT A LOWER LIMIT TO THE IMPEDANCE VARIATION WITH SCANNING 4HIS IS INDICATED BY !LLENS RESULTS  WHERE IMPEDANCE VARIATION WITH SCAN 
 SIGNAL POLARIZATION 4HE SECOND GRAPH USES COMPONENTS OF THE  RECEIVED SIGNAL THAT ARE ORTHOGONAL TO THE TRANSMITTED SIGNAL &IGURE  GIVES A WIDELY QUOTED EXAMPLE OF THIS TYPE OF DISPLAY FOR IMAGES OF  3AN &RANCISCO 4HE AXES IN THE HORIZONTAL PLANE ARE THE ORIENTATION ANGLE FOR THE  SYNTHESIZED TRANSMITTED SIGNAL  XT AND ITS ELLIPTICITY ANGLE  BT 4HE VERTICAL AXIS IS RELATIVE  POWER 6ALUES OF  XT   n AND n ARE HORIZONTAL POLARIZATION  WHEREAS  XT   n IS VER 
 TO 
 information might be obtained about  some targets that cannot be as readily obtained at lower frequencies (long wavelengths). Also  the cross sections will be greater for those scatterers which are comparable in size to the radar  wavelength. In the millimeter region, however, resonances of the atmospheric constituents are  excited (in particular oxygen and water vapor) which result in attenuation that can be  relatively high, even in the clear atmosphere. 
 &- WAVEFORM IS THAT IT IS LESS  DOPPLER TOLERANT THAN THE ,&- )N THE PRESENCE OF DOPPLER SHIFT  THE TIME SIDELOBES OF THE PULSE 
 If the samples are dependent, one can either use a two-parameter (mean and variance) threshold or adapt a one-parameter threshold on a sector basis. These rules should serve only as a general guideline. It is highly recommended that before a detector is chosen the radar video from the environment of interest be collected and analyzed and that various detection processes be simulated on a computer and tested against the recorded data. 
 The radiation level in the back hemisphere is a  function of the feed gain, reduced by the transmission loss through the reflector. Thus,  the reflector designer must consider both the leakage loss and the transmission loss  (Figure 12.9). There are, however, additional backlobes that are distinct from the back radiation due  to surface leakage. 
 T., and C. T. Leondes: Minimum Number of Satellites for Three- Dimensional Continuous Worldwide Coverage, IEEE Trans., vol. 
 Harmful effectsofexcessive microwave radiation resultfromeitherageneralriseinthe totalbodytemperature orfromselective heatingofsensitive partsofthebody.Exposure ofthe wholebodywillcausetheinternal temperature toriseandproduce fever.Anincrease in thetotalbodytemperature of1°Cisconsidered excessive,64 andprolonged exposure ortoo highatemperature risecanbefatal.Discomfort resulting fromageneralriseinbodytempera­ turecanbeperceived bythevictimandserveasawarning. Thedangeroflocalized heatingdepends uponwhether compensating coolingmechan­ ismsexisttodissipate theheatgenerated attheradiated partofthebody.Forexample, localized heatingisleastseriousinmuscletissuewhichiswellequipped withbloodvessels capableofdissipating heat.Heating ismoredangerous inthebrain,thetestes,thehollow viscera,andtheeyes,wherethereislittleopportunity fortheexchange ofheatwiththe surrounding tissue. Manyinstances havebeenreported wherecataracts havebeendeliberately formedinthe eyesofanimals byexposure tomicrowave radiation. 
 Ainsworth, and M. R. Grunes, “Terrain topography measurement  using multipass synthetic aperture radar data,” Radio Science , vol. 
 D ASH CURVE   LEAF  REMOVED THE DOTTED CURVE  LEAF  REMOVED  AFTER , + 7U   ET AL  . £È°{ä  2!$!2 (!.$"//+  "ECAUSE VOLUME SCATTER DOMINATES FOR DENSE VEGETATION  ESPECIALLY TREES   R  IS  NEARLY INDEPENDENT OF THE ANGLE OF INCIDENCE &IGURE  SHOWS THIS WITH RESULTS  FROM 8 
 ING CROSS SECTIONS ASSOCIATED WITH THEM 3IMILAR RECORDS MAY BE FOUND IN REFERENCE 7ARD ET AL  /THER %NVIRONMENTAL %FFECTS 2AIN %ARLY EVIDENCE OF THE EFFECT OF RAIN ON SEA CLUTTER WAS MAINLY ANECDOTAL FOR  EXAMPLE  RADAR OPERATORS WOULD REPORT  THAT SEA CLUTTER TENDS TO DECREASE WHEN IT STARTS  TO RAIN (OWEVER  THERE HAS BEEN LITTLE IN THE WAY OF RELIABLE  QUANTITATIVE EXPERIMENTAL  INFORMATION ABOUT THE INTERACTION BETWEEN RAIN AND WIND 
 19. Weickmann, H. K., and H. 
 30. R. W. 
 6ERLAG     6 ! !LEBASTROV  ! 4 -ALTSEV  6 - /ROS  ! ' 3HLIONSKIY  AND / ) 9ARKO  h3OME CHARACTERISTICS  OF ECHO SIGNALS v 4ELECOMM AND 2ADIO %NG  VOL   PP n    6 ' 3OMOV  6 ! ,EUSENKO  6 . 4YAPKIN  AND ' 9A 3HAIDUROV  h%FFECT OF NONLINEAR AND  FOCUSING IONOSPHERIC PROPERTIES ON QUALITATIVE CHARACTERISTICS OF RADAR IN THE DECAMETRIC 
 Note that the filter peaks are fairly evenly distributed. The dip between the first zero-doppler filter and the first moving doppler filter is larger than the others, primarily be- cause, under the constraints, it is impossible to move the first doppler filter nearer to zero velocity. Chebyshev Filter Bank. 
 78, pp. 7823–7833, 1973. 29. 
 40. B. L. 
 The tachometer provides a negative feedback voltage proportional to the servomotor speed. As the servomotor rotates the an- tenna toward a target, the error voltage decreases, dropping to zero when the an- tenna axis arrives at the target. However, the tachometer feedback provides a retarding motor torque opposing the system inertia that causes the overshoot, thus reducing the overshoot. 
 The R/P  can be reflective or absorptive, but must have low insertion loss to minimize impact  on receive chain noise figure. Clutter Automatic Gain Control (CAGC).  The CAGC attenuator is used both for  suppressing transmitter leakage from the R/P into the receiver (so the receiver is not  driven into saturation, which could lengthen recovery time after the transmitter is  turned off) and for controlling the input signal levels into the receiver. 
 TYPE ANTENNA PEDESTAL  THERE ARE TYPI 
 To handle the maneuver­ ing target, some means may be included to detect maneuvers and change the values of a. and P  accordingly. In some radar systems, the -data rate might also be increased during target  maneuvers. 
 A plot in  rectangular coordinates is shown in Fig. 5.lb, and the error signal obtained from a target not  on the switching axis (reference direction) is shown in Fig. 5. 
 BEAM CLUTTER 
 Published by University of California  Press. Berkeley. 1964. 
 There are no explicit requirements on other antenna parameters for SOLAS- approved systems, such as beamwidths and gain, but these obviously need to be com - patible with the total radar performance requirement. For instance, azimuth resolution  has to be better than 2.5°; target bearing has to be determined to within 1°; and the  system must operate in conditions when the ship is rolling and pitching ±10°. Typical  antenna gains and beamwidths have been outlined in Section 22.2. 
 When k = 1, the peak response occurs atf= 1/NT as well asf= 1/T + 1/NT, 2/T +  l/NT, etc. Fork= 2, the peak response is at f = 2/NT, and so forth. Thus each value of the  index k defines a separate filter response, as indicated in Fig. 
 The percentages are based on experience and nego - tiations with the subsystem designers. A possible allocation is provided in Table 4.6. Discretes. 
 An example of a complete doppler filter bank imple- mented with nine uniformly spaced filters is shown in Fig. 15.28. The perfor- mance of this doppler filter bank against the clutter model considered in Fig. 
 The dipole is always used  over a reflectirig ground plane, or its equivalent, in order to confine the main beatn'radiation to  the forward direction.  Slots cut into the walls of a waveguide are similar in many respects to the dipole since the  lot is the Babinet equivalent of the dipole. A slot array is generally easier to construct at the  tiiglier microwave frequencies than an array of dipoles. 
 3.17. The frequency translation in tlie  reference signal path is equivalent to a doppler shift in the antenna path. The frequency  excursion of the modulation waveform can be adjusted by a servomechanism to maintain the  rnaxirnum of the Bessel function at the aircraft's altitude. 
 Knott et al., Ref. 14, p. 471. 
 PROCESSING APPROACHES TO PROVIDING THE  MATCHED FILTER FOR A PULSE COMPRESSION WAVEFORM )N BOTH CASES  THE INPUT SIGNAL IS THE COMPLEX ENVELOPE SEQUENCE AS FORMED USING EITHER DIGITAL DOWN 
 ;.J ^1  The measurement of noise figure can be made during radar operation without degrading  the receiver seilsitivity by pulse-modulating the noise source in synchronism with the radar  trigger and injecting the noise into the receiver during the " flyback " or "dead time" of the  radar, just prior to the triggering of the next transmitter pulse. The measurement of the  receiver output with the noise source on (N2) and the noise source off (NI) can be made on  alternate pulse periods.  The receiver noise-figure or sensitivity can also be measured by use of a calibrated signal  generator. 
 (('orr~.ft,s~ RC.4. 111(..) -  computer-controlled multifunction radar. The various functions to be perfor~rled must be  efficiently prioritized so as not to exceed either resource. 
 REFLECTORS "ISTATIC LOSSES SHOULD NOT BE AS SEVERE FOR TARGETS WITH BLENDED SURFACES AND A LESS COMPLEX STRUCTURE  SUCH AS COMBAT AIRCRAFT 'LINT 2EDUCTION IN THE "ISTATIC 2#3 2EGION  ! SECOND EFFECT CAN OCCUR IN THE  BISTATIC REGION 7HEN THE BISTATIC 2#3 REDUCTION IS CAUSED BY A LOSS OR ATTENUATION OF . 
 TIONAL (& SKYWAVE RADARS IS PRESENTED  IN 4ABLE   ILLUSTRATI NG THE DIVERSITY OF ENGI 
 METEOROLOGICAL RADAR  19.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 measured by the radar system. It also encompasses items such as knowing where the  scattering volume is in 3D space by knowing antenna pointing angles and accurately  determining range. Although floating spheres, tetrahedral reflectors, and other targets of known radar  cross section may be used,26,73 the important “solar calibration” technique uses the  solar position to adjust antenna pointing and the radiated solar flux to determine  antenna gain.74,75 Along with other radar parameter measurements, one can read - ily determine the radar constant. 
 ... ..‘., ,.... ,.. 
 IZATION  COARSE RESOLUTION 3CAN3!2  M AT  KM  DUAL 
 16,  McGraw-Hill Book Co., New York, 1947.  2. White, W. 
 Author Contributions: The work presented here was carried out in collaboration among all authors. conceptualization, Y.W. and W.Y.; formal analysis, Y.W. 
 ING ACCURACY OF MONOPULSE RADAR SYSTEMS v 0ROC )2%  VOL   PP n  -ARCH   $ # #ROSS AND * % %VANS  h4ARGET GENERATED RANGE ERRORS v IN  )%%% )NT 2ADAR #ONF 2EC    !RLINGTON  6!  !PRIL n    PP n  $ * 0OVEJSIL  2 3 2AVEN  AND 0 7ATERMAN   !IRBORNE 2ADAR  0RINCETON  .* $ 6AN .OSTRAND  #OMPANY    PP n  2 (YNES AND 2 % 'ARDNER  h$OPPLER SPECTRA OF 3 BAND AND 8 BAND SIGNALS v  )%%% 4RANS 3UPPL    VOL !%3 
 Figure 6.10  Probability of Detection Pd, as a function of the detection threshold.  . Radar System Engineering  Chapter 6 – Radar Receiver Noise and Target Detection  38     6.6 Radar Detectors   In practice essentially tw o detector procedures are used, the envelope detector and the I/Q d e- tector. 
 A VSA can use   a Fast Fourier Transform (FFT), or other Discrete -Time  Frequency Transformation  (DTFT) , to make such a spectrum  plot of a single pulse. A swept spectrum analyzer must either  be in a "maximum trace hold" mode, or it must sweep slowly  enough that at least o ne pulse appears at each position  across the screen to provide a comp lete spectrum view.  Without additional frequency processing software, the  oscilloscope provides only the voltage waveform. 
 VIC Nos. 228 and 461 Squadrons with Sunderland Mk. V;ASV Mk. 
 34. Kendrick, J. B. 
 PULSE VIEW v  )%%% 4RANS  VOL !0 
 Lens  reflections may also be reduced with transition surfaces as in optics. These surfaces should be a  quarter wave thick and have a dielectric constant which is the square root of the dielectric  constant of the lens material.  Artificial dielectrics. 
 It is well known that slowing the rise - and fall -times of the transmitted pulse envelope can  reduce the amount of ripple in the signal spectrum, but this approach is often tec hnologically  difficult to implement in Radar transmitters, and wi ll result in reduced transmitter efficiency.  However, some slowing of the rise - and fall -times is always r equired to meet spectrum control  requirements and for this reason a 1 µs rise-  and fall -time was assumed for the waveform d e- signs presented in this pap er. Several papers have reco gnized that low spectral ripple, nonli n- ear chirp waveform designs can be achieved for low time- bandwidth products by adding very  rapid frequency excu rsions at the start and end of the chirp waveform [8 -9]. 
 pp. 578-584, September,  1963.  100. 
 Refocusing of moving targets in SAR images based on inversion mapping and ISAR processing. In Proceedings of the 2011 IEEE Radar Conference, Kansas, MO, USA, 23–27 May 2011; pp. 68–72. 
 %23 
 # * )! $"%$##('  (&$''$& 
 This surface wave is important since it can cause a large reflection (and an accompanying loss of the beam) for some angles of scan. This can best be seen by examining the condition of phasing for which the couplings from many elements will add in phase to cause a large reflection in a typical element. Consider an array in which the velocity of the surface wave is that of free space. 
 Other functions discussed in this chapter are not required for this radar application  because they do not limit performance. Examples include scanning motion compensa - tion and multiple spectra AMTI clutter cancellation. REFERENCES  1. 
 Limiters, however, can generate undesired spurious responses and small-signal suppression.  and reduce the improvement factor that can be achieved in MTI processors. It should therefore  be used with caution as an ECCM device. 
 BAND DOPPLER SPACE FOR THE ABOVE RADAR PARAMETERS IS  MS  AND ASSUMING THAT THE LAND CLUTTER SUPPRESSION REGION HAS TO BE  o  MS AND THAT THE MOVING CLUTTER SUPPRES 
 This is done by taking a sample of the transmitted pulse at a directional coupler, mixing this pulse with the stalo (stabilized local oscillator) and then using this pulse to phase-lock the coho (coherent oscillator). The coho then becomes the reference oscillator for the received signals. (The stability requirements for the coho and stalo will be de- scribed in Sec. 
                 . Óx°ÓÓ  2!$!2 (!.$"//+  BY DIGITIZED SINE AND COSINE  WAVEFORMS FOR THE MODULATION CARRI ER FREQUENCY  PRODUC 
 on Geosc. and Remote Sensing , vol. 35, pp. 
 As we shall see, Gee has a maximum range of  about 400 miles. It set a completely new standard of  accuracy in radio navigation when it was first introduced  by the Malvern experts for Bomber Command, and  heavy raids at night over Europe would not have been  possible if we could not have covered Europe with the  invisible but very tangible Gee lattices. Loran, the  American long-range modification of Gee, working by  reflection from the ionosphere, became very useful over  longer distances of even up to 1000 miles, although it  was conceded that over shorter ranges Gee was more  accurate, and that Loran should, for all normal pur-  poses, take up where Gee left off. 
 Consequently, we know that c2=0. At r→∞,Γ→Γ0, we can obtain c1=Γ0/H(∞). Following this, the circumferential velocity Vθcan be computed as Vθ=H(r) 2πrH(∞)Γ0 (7) To determine the unknown relationship between the axial velocity Vz, the radial velocity Vrand r, it is assumed that the Vzis independent of the radial coordinate rand has a linear relationship with z, i.e., Vz=αz,α>0 (8) where αis a constant named suction intensity. 
 JAMMING WHEN USING CONTINUOUS WAVEFORMS AND TO SEPARATE THE TRANSMIT AND RECEIVE RANGE AMBIGUITY ZONES IN AZIMUTH 4RANSMIT RADIATING ELEMENT CHOICE IS  DRIVEN PRIMARILY BY THE RANGE OF FREQUENCIES  TO BE RADIATED AND THE WAVEFORM BANDWIDTH  BUT IT MUST ALSO TAKE INTO ACCOUNT THE RANGE AND AZIMUTH COVERAGE REQUIRED  THE ASSOCIATED COVERAGE RATE  AND CONCERNS ABOUT CLUTTER  ESPECIALLY SPREAD 
 10. Rowe, A. P.: "One Story of Radar," Cambridge University Press, New York, 1948. 
 In (he usual integrator, the full energy of the interference pulse is added. In the binary  moving-window detector, however, it contributes no more than would any other pulse that  crosses the first threshold since a I is recorded no matter what the amplitude. Similarly, the  double-threshold detector has some advantage over the usual integrator when the background  interfereuce is not receiver noise but is nongaussian, as is some sea clutter and land clutter. 
 D" AND  
 The contour map, range and azimuth slices are shown in Figure 11. The central point target in red square is selected to perform a detail analysis. The ideal imaging result in Figure 11a has sub-meter level azimuth resolution with 0.713 m in azimuth and 2.26 m in range by using the default system parameters. 
 The straight line is a saturation asymptote, and for this example the limit is ap- proached at the higher frequencies. The scale marked "wind velocity" can be used to deduce that winds up to 40 kn have excited waves with frequencies as low as 0.08 Hz but that either the length of time or the fetch, or both, have not been sufficient for full development. In this example the individual spectral analyses, requiring about 100 s of data, have been averaged for !'/2 h. 
 The radar uses 1792 active transceiver modules per face to feed dipole antenna elements. Extra elements and a narrow beam are used on receive, and upgrade capability has been included for the future installation of up to 5354 transceiver modules per array face. The peak power output from each face of the baseline system is 600 kW, and the average power output is 150 kW. 
 M.: "Probability and Information Theory with Applications to Radar," McGraw-Hill  Book Company, New York, 1953.  27. Woodward, P. 
 The effect of the duct on the line-of-sight propagation is to  reduce the angle of the lowest lobe, bringing it closer to the surface.5 10000 8000 6000Nulls Lobe Radar hole Terrain blockage4000Height (ft) 2000 0 0 0 110 115 120 125 130 135 1402040 Skip zone Loss{dB}:Range (nmi)60 80 100 FIGURE 26.2  Ducting consequences ch26.indd   8 12/15/07   4:53:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation. 
 Theantenna isthen stabilized abouttheazimuth axisifthepitchangleissmall. Thethree-axis mountof(e)canprovide fullhemispheric coverage. Themountin(I) mightbedesiredwhereantenna elevation isnotrequired. 
 Therefore, the received echoes are spatially coherent, and additional pulse information about the target may be acquired with the observed pulses. By exploiting this spatial continuity information, we can try to extrapolate or predict the echo information outside the observed CPI. In order to demonstrate the assumption that the echoed signal is continuous in the spatial space with a short dwell time, two slow moving targets modeled with Swerling I [ 1] are injected into the real airborne radar data set. 
 GPR is a successful example of  the exploitation of ultrawideband radar and typically a GPR with a range of 1 m would  operate over the range 0.3 GHz to 3.3 GHz. Although GPR has many similarities to radar systems, there are some key differ - ences, which need to be appreciated when comparing them with conventional radar  systems. GPR systems are a special class of ultrawideband (UWB) radar system and  can radiate energy in the range of frequencies from a few MHz up to 10 GHz with a  bandwidth of up to a decade, but more usually 2–3 octaves. 
 GAIN  NARROW 
 Hudson, and J.-L. Margot, “Advances in planetary radar astronomy,”  Chapter 35, in Review of Radio Science, 1999 –2002 , R. Stone (ed.), Oxford: U.R.S.I, 2002,   pp. 
 but storm clouds are what the radar meteorologist wants to see in order to measure rainfall  rate over a large area. The backscatter echoes from land can degrade the performance of many  radars; but it is the target of interest for a ground-mapping radar, for remote sensing of the  earth resources, and for most synthetic-aperture radars. Thus the same object might be the  desired target in one application, and the undesired clutter echo in another. 
 Some  examp les are airspace surveillance, linking with spacecraft and/or satellites, or for use in mil i- tary applications.  The accuracy of the angle position (≈  θHB/2), attainable with the directivity  of the antenna, is not sufficient.  The measurement of Δx of an ob ject over the resolution at a  range R, realizable by the half -power bandwidth ΘHB of the a ntenna, is large for greater dis- tances. 
 -  Ê",Ê/ 
 Extended Multiple Aperture Mapdrift-Based Doppler Parameter Estimation and Compensation for Very-High-Squint Airborne SAR Imaging. Sensors 2019 ,19, 213. [ CrossRef ] [PubMed ] 5. 
 This provides a stable reference in the absence of clutter. An input from the aircraft inertial navigation system and the FIG. 16.5 Block diagram of a radar illustrating the signal flow path of the TACCAR control loop.TRANSMITTER MODULATORUPCONVERTERSYSTEMREFERENCEOSCILLATORFREQUENCYDISCRIMINATORAFCFILTER FREQUENCY ERROR VOLTAGE-CONTROLLEDOSCILLATORERRORSUM •Vg cos aFROM NAVIGATION SYSTEM STABLELOCALOSCILLATOR WAVEFORMGENERATOR RECEIVERPREAMPIFAMPSYNCHRONOUSDEMODULATORMTI INPUTUNDELAYEDDELAYEDLOWPASSFILTER DELAYTp PHASEDETECTOR GATE CLUTTERENVELOPEDETECTIONLOGICDOWNCONVERTER . 
  ACTION v "ULL !MER -ETEORO 3OC  VOL   PP n    %  "ROOKNER  ED    0RACTICAL  0HASED  !RRAY  !NTENNA  3YSTEMS    .ORWICH   -! !RTECH   (OUSE     * 7URMAN AND - 2ANDALL  h!N INEXPENSIVE  MOBILE  RAPID SCAN RADAR v IN  TH )NT #ONF ON  2ADAR -ETEOROL  -UNICH  !-3    PP n  * 7 2OGERS  , "UCKLER  ! # (ARRIS  - +EEHAN  AND #  * 4IDWELL  h(ISTORY OF THE 4ERMINAL  !REA 3URVEILLANCE 3YSTEM 4!33  v IN   TH  #ONF  2ADAR  -ETEROL   !-3  !USTIN      PP n. £°{n  2!$!2 (!.$"//+   7 "ENNER  7 ' 4OROK  . 'ORDNER 
 SCALE 
 L.R.,andB.Gold:..TheoryandApplication ofDigitalSignalProcessing," Prentice-Hall. Inc..Englewood Clirfs.N.J..1975. XI.Thomas. 
 Therefore, the resulting phase waveform takes on a  sawtooth pattern, linearly ramping from 0o to not quite 360o and then resetting to 0o  and ramping again. An important feature of an NCO for a radar application is the CLEAR signal shown  going to the phase accumulator register. For a coherent radar exciter implementa - tion, the transmit signal must start at the same phase on every pulse. 
 Even the best systems still have overall  power efficiencies (prime power in to RF out in space) in the 10–25% region in spite  of years of development. The typical AESA requires low voltage and high current  at the T/R channel. This forces large conductors in the absence of high power light - weight superconductors (not available at this writing). 
 67. Waite, A. H., and S. 
 Lieb~nan: A Report on the Sperry Dome Radar. Microrc!utw J., vol. 22. 
 Itis desiredtomakethegateassmallaspossible soastoavoidhavingmorethanoneechofall withinitwhenthetrafficdensityishighorwhentwotracksareclosetooneanother. However, alargegateareaisrequired ifthetrackeristofollowtargetturnsormaneuvers. Morethan onesizegatemighttherefore beusedtoovercome thisdilemma. 
 Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 90     € m=tanεwith −45°≤ε≤+45°    Thus waves without ellipticity ( ε=0) are linearly polarized.  Those with ε=±π/4 are circular.   With the decision of the propagation direction and  of the sign (+/ -) the polarization will be  defined as left-  (ε>0) or right -handed (ε<0). 
 'I'nylor. J. W., Jr.: Iligital M'I'I Ratiar Systcln, U.S. 
 106. Oh, L. L., C. 
 BEAM  CLUTTER AND MAXIMIZING TARGET SIGNAL 
 F    3IGNAL TIME REVERSAL   X T  8  
 AES-14, pp. 750-755. September,  I97X. 
 It has also been noted that only some parts of an object can be detected as a change, and the detected parts can be used as a guide to segment the full object. Objects that are close to one another can be merged to provide a more holistic analysis of the scene and further reduce the number of false positive object detections. However, it must be concurrently ensured that false positive reduction is not overly aggressive to the point that false negatives are generated. 
 Y 
 Attenuation byoxygenandwatervaporisshowninFig.12.9.44•45Resonance peaksfor watervaporoccurat22.24GHz(1.35cmwavelength) andatabout184GHz,whilethe 10-- E.x......... CDu c0.1 "0 += 0 :J C ~ <1 0.01 0001--n I \ I \ / / / / / / / / / / 24 6 10204060100 Frequency. GHz200 Figure12.9Attenuation ofelectromagnetic energybyatmospheric gasesinanatmosphere at76em pressure. 
 GYRATION OF THE DISTRIBUTION OF THE REFLECTING AREAS IN THE RANGE DIMENSION BASED ON MANY MEASURE 
 TIME CHARACTERISTIC OF THE WAVEFORM  RANGE SIDE 
 Hecht, B. Berking, G. Büttgenbach, M. 
 Similarly, a signal introduced into the fourth port will  TIll'I'I.ITTRONICALLY STI'I'RI'D PHASEU ARRAY ANTENNA INRADAR3tt ------.._-------------, BeamBeamBeam No.3 NO.2No.1 Figure8.25Simultaneous postarnplifier heamformation. rPo=constant phase;IrPI-rPoI=I~rPI '2rr(d/I.) sin°0I. comenient method forobtaining multiple beamsatIF.Beam-forming atIFispossible since phaseispreserved duringfrequency translation fromRFtoIF(exceptfortheconstant phase shiftintroduced bythecommon localoscillator). 
 Unfortunately, the reporting of radar sea echo measurements is sddorn  accompanied by a complete description of the sea and wind conditions.  Variation with grazing angle. There are usually identified three scattering regions according  to the grazing angle. 
 36-42.47-53, April, 1976.  48. White, W. 
 FREQUENCY BUT HAS A BANDWIDTH OF  y S &OR EXAMPLE  IF  S      MICROSECOND   "PULSE     -(Z 4HIS IS FAR LESS THAN THE BANDWIDTH OF THE OVERALL  STEP 
 PULSE STAGGERING IS THAT IT MAY PERMIT ELIMINATING THE USE OF FEEDBACK IN THE CANCELERS USED TO NARROW THE BLIND 
 For standard constant PRF radars,   10-cm wavelengths have been widely chosen for most precipitation measurements  of interest in which design parameters such as radar beamwidth, size of antenna, and  attenuation effects may be made acceptable. Ground Clutter Effects.  Many meteorological radar applications call for the  detection of precipitation echoes in the presence of ground clutter. 
 82-92  FM pulse compresoion. 422-427  Foam shell radome, 267  Focused SAR, 519  Forward scatter. 553  Fox phase shifter. 
 73. Jackson, M. C.: The Geometry of Bistatic Radar Systems, IEE Proc., vol. 
 Ward, H. R.: Dispersive Constant False Alarm Rate Receiver, Proc. IEEE, vol. 
 !i ,+_IT' -j.: I I : I, r' , t++-+-+-+-+-+-~--j,-+--+---,----+--+-+--+I--+-l- .-------'--'- -_c.,......-,--"--,_......-. ..-;-...., .-----~- -T----..,- '1IIi ~I I I , !j, . '1.0. 
 The RCS can rise to significant levels at end-on aspects, as well as in the broadside  regions, of bodies both fat and thin. These near-end-on echoes are attributable to sur - face traveling waves that radiate power in the backward direction. An example is the  ogive, a spindle-shaped object formed by rotating an arc of a circle about its chord. 
 If we assume a Rayleigh distribution of fading, the number of independent samples required for a given accuracy is shown in Fig. 12.16. The range defined in this figure is the range of mean values lying between 5 and 95 percent points on the distribution. 
 A: receiver; B: waveform generator; C: power unit 567; D: power unit 617A; E: monitoring unit [ 20].Airborne Maritime Surveillance Radar, Volume 1 4-23. Figure 4.30. Switch unit type 247 [ 6]. 
 RELATED  PLUS JAMMING SPATIALLY CORRELATED   AND 2S IS THE SIGNAL COVARIANCE MATRIX 4AXONOMY OF 34!0 !RCHITECTURES 7ARD  4HE APPLICATION OF THE ADAPTIVE  WEIGHT EQUATION FROM %Q  IN A RADAR SYSTEM PROVIDES NUMEROUS OPTIONS AND COM 
 Ifthesweep length were equivalent to,forexample, 500 intervals (remember that what wecall an“interval” isabout I/@ long), one would expect tofind several (roughly, five) noise peaks inthe sweep which were higher than the signal peak. Inthis case weshould certainly need either astronger signal ormore integration. Now itisthetrendofth6numbers inTable 2.1which isofinterest to us,since any real radar problem will differ inmany particulars from the ideal process towhich Table 2.1applies exactly. 
 PLANE HORN AS SHOWN 3UBARRAYS 4HE PHASED 
 The trapping layer is indicated graphically by the solid  black M-unit versus height line where the slope of the line is negative ( M-unit decrease  with height). The first type of duct is a surface duct created from a surface-based trapping layer.  This duct is referred to as a surface  duct and is illustrated in Figure 26.4. 
 A change in  the magnitude of the correction factor or even the compensation pattern with range,  height, and velocity could be utilized to retain performance. Figure 3.22 illustrates the theoretical MTI performance of a CPCT system as a  function of beam-pointing direction and interpulse motion normalized to the interpulse  motion used to design the compensation pattern. ( Cancellation ratio  is defined as the  ratio of input clutter power to output clutter residue power.) The peak on the 90° axis  is typical of the optimized DPCA performance illustrated in Figure 3.12. 
 FOURTH  OF THE BEAMWIDTH AT THE ANGLE OF SCAN AS THE FREQUENCY IS CHANGED OVER THE BAND )F ALL  THE FREQUENCIES IN THE BAND ARE USED WITH EQUAL WEIGHTING  THEN TWICE THE BANDWIDTH HALF THE PULSE LENGTH  BECOMES ACCEPTABLE !T A SCAN ANGLE  P   THE BEAM STEERS WITH  FREQUENCY THROUGH AN ANGLE CP SO THAT   DDPPyF FTAN RAD   &OR  WIDER BANDWIDTHS  TIME 
 Unfortunately, this would also limit  any processing gain that the FFT might offer. A third method, called block floating point,  checks the magnitudes of all the out - puts after each stage is computed and provides a single exponent for all output values.  If any of the outputs have overflowed or come near to overflowing, then all of the  outputs are scaled by a factor of 0.5, and the common exponent is incremented by 1. 
 The front face and the metal backing of the Dällenbach layer are its only sources  of reflection. The use of physically realizable materials makes it impossible to force  either reflection to zero. The design objective, therefore, is to choose the electrical  properties of the layer so that the front-face and metal-back reflections tend to cancel  each other. 
 TIP  WITH AN EFFECTIVE FOOTPRINT OF SEVERAL TENS OF KM 0EAK OUTPUT POWER IS  7 )NSTRUMENT MASS IS  KG AND INPUT POWER  7 !TMOSPHERIC  )ONOSPHERIC 3OUNDINGn&LIGHT 3YSTEMS   4HE OBJECTIVE OF THIS  CLASS OF RADAR SOUNDERS IS TO GENERATE A CROSS 
 The U function for a certain pair of angles  (q, f) determines, after comparison with a suitable threshold, if a target is detected.  The same U functional when scanned across a suitable set of ( q, f) angle values  provides, by means of Eq. 24.11, the target DoA estimate. 
 The backscat­ ter from snow-covered terrain is dependent on the wetness, or amount of liquid and solid  water in the snow, more so than the thickness of the snow. It was found,46 for example, that  15 cm of dry powderlike snow had no effect on the measured backscatter over the frequency  range 1 to 8 GHz. Any backscatter contribution by the snow was completely dominated by  the contribution of the underlying soil. 
 TO 
 Methods for the design of optimal receivers for the detection of moderately  fluctuating signals have been con~idered.~~  It is difficult to be precise about the statistical model to be applied to any particular  target. Few, if any, real targets fit a mathematical model with any precision and in some cases  it is not possible to approximate actual data with any mathematical model. Even if the  statistical distribution of a target were known, it might be difficult to relate this to an actual  radar measurement since a target generally travels on some well-defined trajectory rather than  present a statistically independent cross section to the radar. 
 ITY OF SCATTERERS ON THEM OR BECAUSE OF THE COMPLEXITY OF THEIR SURFACE PROFILES AND DIELECTRIC CONSTANTS )NSECTS ARE EXAMPLES OF THE LATTER -EASURED VALUES FOR A DOZEN SPECIES OF INSECTS ARE LISTED IN 4ABLE  4HE  BUGS WERE ALIVE FOR THE MEASUREMENTS BUT HAD TO BE DRUGGED TO IMMOBILIZE THEM &IGURE  SHOWS THE RELATIONSHIP BETWEEN THE 2#3 AND THE MASS OF AN INSECT  WITH THE VARIATION OF A WATER DROPLET SHOWN FOR COMPARISON 4ABLE  LISTS THE 2#3 OF A MAN AS REPORTED BY 3CHULTZ ET AL  /THER COMPARISONS HAVE BEEN MADE  FOR BOTH BIRDS AND INSECTS&)'52%   2#3 PATTERNS OF A TRIHEDRAL CORNER REFLECTOR %DGE  OF APERTURE     IN K    CM  3 3 2OBERTSON Ú !44   2EPRINTED WITH PERMISSION FROM !44 4ECHNICAL *OURNAL  &)'52%   #OORDINATE SYSTEM FOR THE 2#3 PATTERNS IN  &IGURE  3 3 2OBERTSON Ú !44  2EPRINTED WITH  PERMISSION FROM !44 4ECHNICAL *OURNAL  . £{°£Ó  2!$!2 (!.$"//+  &REQUENCY  '(Z 2#3  M  n  n n n n4!",%  -EASURED 2#3 OF A -AN)NSECT ,ENGTH  MM 7IDTH  MM"ROADSIDE  2#3  D"SM%ND 
 P. A .. and I. 
 pp. 423 426. Oct. 
 Antennas Propag ., vol. 38, no. 12, December 1990. 
 A modified version of binary integration is sometimes used when there is a large number of pulses. It also has flexibility to integrate a different number of pulses. The modified binary moving window (MBMW) differs from the ordinary binary moving window (OBMW) by the introduction of a third threshold. 
 f:XIR/\CTION OF INH>RMATION AND WAVEFORM DESIGN 419  (al Knife edge (ridge) (b) Bed of spikes  {c) Thumbtack  Figure I 1.13 Classes of ambiguity diagrams: (a) knife edge, or ridge; (b) bed of spikes; (c) thumbtack.  (From G. W. 
 for each channel. All three mixers operate  from a single local oscillator in order to maintain the phase relationships between the three  channels. Two phase-sensitive detectors extract the angle-error information, one for azimuth,  the other for elevation. 
 ÓÈ°Ón  2!$!2 (!.$"//+    + ' "UDDEN   4HE  7AVE 
 17.2, the method ofangular increments usually involves, asafinal stage, asynchronous motor driven byasinusoid. Three methods ofrelaying thenecessary data have been used. Inthe first method, the sinusoid itself may betransmitted directly onasubcarrier. 
 Therefore, ifoneradarwere"blind" tomovingtargets,itwouldbeunlikelythattheotherradarwouldbe"blind"also.Insteadof usingtwoseparate radars,thesameresultcanbeobtained withoneradarwhichtime-shares itspulserepetition frequency between twoormoredifferent values(multiple prf's).Thepulse repetition frequency mightbeswitched everyotherscanoreverytimetheantenna isscanned a halfbeamwidth, ortheperiodmightbealternated oneveryotherpulse.Whentheswitching is pulsetopulse,itisknownasastaggered prf.. Anexample ofthecomposite (average) response ofanMTIradaroperating withtwo separate pulserepetition frequencies onatime-shared basisisshowninFig.4.16.Thepulse. MTI AND PULSE DOPPLER RADAR 115  o ?/r,  1- r equericy  o 3/r. 
 range). A single sweep on an A-scope might appear as in  Fig. 4.3f1. 
 The many problems that enter into thecreation ofanadequate organization forthe useofradar data have notreceived thestudy that they should. Despite this fact, Chap. 7attempts toprovide anintroduction tothis sort of planning, and toraise some oftheimportant problems, even though they may not yetbesatisfactorily solved. 
 This type of construction, whereby a spherical structure is constructed  from flat plastic panels of simple geometrical shapes, is sometimes called a geodesic dome. The . 266 INTRODUCTION TO RADAR SYSTEMS  Figure 7.29 Rigid radome for ground-based antenna. 
 Lind, G.: Reduction of Radar Tracking Errors with Frequency Agility, IEEE Trans., vol. AES-4, pp.  4IO 416, May, 1968. 
 Both input and output coaxial lines end incoupling loops which play the role ofthe step-up and step-down transformers. They can bethought ofassingle-turn windings which, inproportion totheir area, loop more orless ofthemagnetic field existing inthecavity. The smaller theloop, thehigher the step-up ratio and the higher the loaded Q. 
 CUTTER FOOTPRINTS  HOWEVER  SINCE THE ANTENNA  BEAM WILL HAVE A COMPLEX PROFILE AND THE PULSE MIGHT BE SHAPED &OR THIS REASON   AN EFFECTIVE  ! MUST BE OBTAINED FROM A SURFACE INTEGRATION OF THE ACTUAL AMPLITUDE  PROFILE OF THE FOOTPRINT  WHICH WILL TEND TO RESULT IN A SMALLER VALUE OF  ! THAN THAT  DEFINED BY %Q  OR %Q  4HIS WILL PRODUCE LARGER VALUES OF  R   AS DERIVED  FROM MEASURED VALUES OF  RC BY %Q  -OST EXPERIMENTERS USE THE HALF 
 56.Dinneen, G.P..andI.S.Reed:AnAnalysis ofSignalDetection andLocation byDigitalMeans,IRE 'j/ Trans..vol.1'1'-2,pp.29-38,March,1956. 57.Dillard.G.M.:AMoving-Window Detector forBinaryIntegration, IEEETrans.,vol.IT-13,pp.2-6, January, 1967. 58.Worley, R.:Optimum Thresholds forBinaryIntegration, IEEETrans.,vol.IT-14,pp.349-353, March,1968. 
 Pawlikowski, “High-power gridded tubes— 1972,” Proc. IEEE , vol. 61, pp. 
 Smder Mobfle Units.-If highreliability isrequired, thesame considerations must beobserved inthis case asinthe case oflarge systems, notwithstanding theweight penalty. For example, anavigation aidrequired tooperate 24hours per day under allconditions must use conservative, long-lived prime movers and beprovided with standby equipment, though itmay consume only 75o watts. Much design effort has been expended onpackaging units ofabout 500-lb weight and 5-kw output inareadily portable form, There has also been much development oftwo-cycle gasoline engines for power units uptoabout 2-kw output. 
 Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 8.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 product detection followed by A/D conversion in each baseband channel. Figure 8.27 a  shows a digital implementation of a time-domain convolution processor that will pro - vide matched-filter performance for any radar waveform. 
 PULSE BINOMIAL 
  USED INCLINED DIPOLES TO ADAPT TO GROUND CONDITIONS 4HE POTENTIAL BENEFITS OF FULL POLARIZATION CONTROL ON TRANSMIT HAVE BEEN ASSESSED AND A NUMBER OF EXPERIMENTAL STUDIES CARRIED OUT  BUT NO OPERATIONAL SYSTEM HAS GONE DOWN THIS PATH 4HE ANTENNAS AND POWER AMPLIFIERS USED IN (& BROADCAST STATIONS HAVE MUCH IN  COMMON WITH (& RADAR  THAT IS  TO MAINTAIN A SPECIFIED LEVEL OF ILLUMINATION OVER A DESIGNATED AREA 4O ACHIEVE THIS GOAL  MANY MULTIBAND AND STEERABLE BROADCAST ANTEN 
 The plasma panel has also been considered as a bright radar  display capable of incorporating alphanumeric labels.59  Types of display presentations. The various types of CRT displays which might be used for  surveillance and tracking radars are defined as follows:  A-scope. A deflection-modulated display in which the vertical deflection is proportional to target echo  strength and the horizontal coordinate is proportional to range. 
 diode,350 Burnthrough, 549 Butlerbeam-forming array,311-314 Csandwich radome, 267 Cancellation ratio.MTI,130 Canonical MTIcombfilter,112 Capillary waves,480 Cassegrain antenna, 240-242 inHawksystem,73 Cathode-driven CFA,212 Cathode pulsing,ofCFA,210 Cathode raytubedisplay,353-359 Cell-averaging CFAR,392-393 CFAR.392-395 inECCM,550 log-FTC, 506 andpulsecompression, 433 Chaff,552-553 Channel tuning,klystron, 204 Chargetransferdevice(CTD),forMTl,126 Chi-square probability densityfunction, 49-51 Chirppulsecompression, 422-427 Circular polarization, andrain,504-506 Circulator, induplexer, 365 Clear-air turbulence, 510-511 Clouds,scattering from,502-503 Clutter,470-512 angel,508-512 land, 489-498 atmillimeter wavelengths, 563-564 sea.474-489 weather. 498-508 Clutterattenuation, MTl,111,130 Clutterdopplerspread,AMTI,142-145 Clutterfluctuations, MTI,131-134. 574 INDEX  Clutter-lock MTI. 
 9.6) inairborne radar, serving, forinstance, asanaidtoairnavigation. Incertain scanners thebeam can beadjusted toaposition above orbelow thehorizon atthe will ofthe operator. The scan rate isusually inthe range between 4 rpm forlarge scanners and 30rpm forsmall. 
 There aretwo chief ones, both having todowith elimination ofground clutter: (1)frequency, and also amplitude, modulation inthe transmitter must beheld tovery low values; and (2)the filters, which reject frequencies O,j,,2~,,etc., present aconsiderable problem. Astothefirst point, theentire operation ofthe system ispredicated ontheassumption that theground returns areperiodic. This assumption would becompletely falsified, iftherange ofaground target, measured in wavelengths, were tochange byaslittle asx/2 inone repetition cycle. 
 To detect targets at ranges masked by the long pulse, a sec - ond (short) pulse 1 µs in duration, and at a different frequency from the long pulse, was  transmitted almost immediately after the long pulse. It detects targets within the range  from 0.5 nmi or less to a range of about 5.5 nmi. The long pulse employs nonlinear FM  pulse compression with a 55:1 pulse compression ratio to achieve a range resolution of  less than 1/8 nmi as required for an air-traffic control radar. 
 Since the detection curve changes shape, the loss depends on the probability of detection selected. A less accurate approximation compares the average signal-to-noise ratio over the interpulse period with the signal-to-noise ratio of the matched case. In the case of M contiguous range gates of width T that occupy the entire interpulse period ex- cept for the transmitted pulse also of width T, the average eclipsing and straddle loss on a signal-to-noise-ratio basis is YEclipse and straddle loss = T, = T^ (17.21)3(M -I- 1) where Y1 = (1 - R) (2 + R) M=I Y = (l - R) (1 - R + 2X) + 2 + 1.75(M - 2) M > 1, R ^ 0.618 Y = (1 - R) (1 + R + Z) + (Z - R) [Z(Z + X)] 4- (1 - Z) [Z(Z + 1) + 1] + 1 + 1.75(M - 2) M>l,R< 0.618 Z = 1/(1 + X) X = Vl - R R =T*/T Tb = width of first gate blanking T = width of transmitted pulse T, and receiver gate T8 M = number of contiguous gates The loss is plotted in Fig. 
 NOISE  RATIO OF THE TRANSMIT 
 MOUNTED  2!2 POINTED PERPENDICULAR TO THE DIRECTION OF FLIGHT HENCE hSIDE 
 H. Meikle, Modern Radar Systems , Norwood, MA: Artech House, 2001, p. 258. 
 White, W. D.: Pattern Lin~itations in Multiple-Ream Antennas, IR t: 'l.rrrri.~.. vol. 
 1977.  44. Potter, K. 
 OF 
 Perhaps the simplest ofthese isthe “shunt peaking” circuit, which uses aninductance inseries with theload resistor, RP.Let theparameter Mbedefined bytheequation L=il{R2C. (12] Then Mcan beused asameasure ofthe performance ofthe circuit. Since avalue ofM=0.25 corresponds tocritical damping, itproduces qoovershoot and yet increases the cutoff frequency byafactor of1.41. 
 The left-hand side of the “bathtub” is  dominated by the lag component, while the right-hand side is dominated by the radar  measurement noise component. Because the gains (horizontal axis) are the designer’s  choice, the single radar ROU is the minimum of the “bathtub” curve. Now consider the fusion of two radars in a particular dimension. 
 TUDE MODULATION  !-  OR A TIME 
    
 The antenna is a 36-in-diameter center-fed parabola with 38.4 dB gain and 1.68° beamwidth. The five-element monopulse feed provides a sum and two or- thogonal difference outputs. The difference outputs are time-multiplexed together into a single receiver difference channel for the angle-tracking operation. 
 IZED BY AGING AND ENVIRONMENTAL EFFECTS  SPECIFIED IN TERMS OF FREQUENCY DRIFT AND MEASURED USING AN !LLAN 6ARIANCE  TECHNIQUE 2EQUIREMENTS ARE TYPICALLY SPECIFIED  IN TERMS OF AN ABSOLUTE FREQUENCY TOLERANCE OR A MAXIMUM FREQUENCY DEVIATION OVER SOME TIME INTERVAL.   2!$!2 2%#%)6%23   È°£x )T SHOULD BE NOTED THAT MEASUREMENTS OF PHASE NOISE ARE TYPICALLY PERFORMED BY  MEASUREMENT OF DOUBLE 
 (5f1). Tliis type of angle mcasurernetit is sitnilar to the phase-comparison monopulse  radar. cxcept that tlie size of the individual antennas is small compared to the spacing between  tliem. 
 L., and J. A. Gaston: On-Axis Pointing and the Maneuvering Target, NAECON '75 Rrcord. 
 £n°xÓ  2!$!2 (!.$"//+  !LTHOUGH THE DYNAMIC RANGE OF THE RAW 3!2 DATA OUT OF A "!1 OPERATOR IS SEVERELY  LIMITED  THE POTENTIAL DYNAMIC RANGE OF THE RESULTING IMAGE DATA IS MUCH LARGER IT IS  BOUNDED ABOVE BY THE PRODUCT OF THE INPUT DYNAMIC RANGE AND THE TWO 
 Pulsed oscillator transmitters, with their independent "carrier" frequency, use automatic fre- quency control (AFC) to maintain the correct frequency separation between the carrier and first LO frequencies. In many early radars, the only function of the local oscillators was conversion of the echo frequency to the correct intermediate frequency. The majority of modern radar systems, however, coherently process a series of echoes from a target. 
 -  4HERE ARE VARIOUS ASPECTS TO RADAR SYSTEM DESIGN "UT BEFORE A NEW RADAR THAT HAS NOT EXISTED PREVIOUSLY CAN BE MANUFACTURED  A  CONCEPTUAL DESIGN HAS TO BE PERFORMED TO  GUIDE THE ACTUAL DEVELOPMENT ! CONCEPTUAL DESIGN IS BASED ON THE REQUIREMENTS FOR THE RADAR THAT WILL SATISFY THE CUSTOMER OR USER OF THE RADAR 4HE RESULT OF A CONCEPTUAL DESIGN EFFORT IS TO PROVIDE A LIST OF THE RADAR CHARACTERISTICS AS FOUND IN THE RADAR EQUA 
 80, pp. 522–545, 1954. 45. 
 Thus it will be more limited in  handwidtli than [nost array feeds. The center-fed feed of Fig. 8.4h does not have this problem. 
 46 THERADAR EQUATION [SEC. 211 Although wehave not arrived atauniversal prescription for the minimum detectable signal power, wehave studied the influence of various factors onS~i~, and weare nowin aposition topredict therelutive change in&i. which will accompany some proposed alteration inthe radar system. 
 traveling-wave tube,andthecrossed-field amplifier. fd To delay-line canceler~Coho-I'-----fc~ Reference signal Figure4.5BlockdiagramofMTIradarwith power-amplifier transmitter.. 106 INTRODUCTION TO RADAR SYSTEMS  RF locking pulse  J1 L I\  Stalo s  To  delay-line  canceler Duplexer  Figure 4.6 Block diagram of MTI radar with power-oscillator transmitter. 
 FREQUENCY  SINGLE 
 Harton. U. K.: "Radars. 
 Within-pulse scanning.40.4\Inthefrequency-scan 3Dradardiscussed above,asinglepencil beamisstep-scanned inelevation. Eachpulseisataconstant frequency butthefrequency is changed everypulseoreveryfewpulsestoposition thebeamatdifferent elevation angles. Another method ofutilizing afrequency-scan antenna istosweepthefrequency overtheentire frl:qUl:ncyrangeon('(lC"pulscsothatencrgy isradiatedthroughou ttheentireelevation covnag.c fortheduration ofasinglepulse.Thefrequency ofthereceived echosignalwill dl:pl:ndonthcelevation angleofthctarget.Abankofcontiguous receivers. 
 MOTION SPECTRUM IS NARROW IN THE FORWARD SECTOR OF COVERAGE WHERE OFFSET ERROR IS MAXIMUM !N OFFSET ERROR OF ONE 
 18. 1961.  35. 
 For a stick of bombs intended to straddle a target, the 50, 100, 150 and 200 ft positions indicated the range that the ﬁrst bomb would be dropped in front of the target. The range lamps operated at ﬁxed distances: green on at 3 miles, off at 1 ½ mile; amber on at 6250 ft, off at 3750 ft; red on just after amber was on and off when the bomb was released. To initiate a Leigh Light attack on a target at a range of less than 10 miles, the operator would stop the scanner to point at a target, using the inching control. 
 BASED RADAR MEASUREMENT OF SURFACE WIND VECTORS OVER THE OCEAN 4HE 3 
 The nonreentrant tube can have either a linear or a circular format, with choice of forward- or  backward-wave interaction. CF As can also be built with an injected electron beam and a  nonemitting sole, but these have not found much application in radar.  The crossed-field amplifier is capable of peak powers comparable to those of linear-beam  tubes, and average powers only slightly less than those achieved with linear-beam tubes.10  Efficiencies greater than 50 percent are common. 
 In addition, Radarsat-2 images have not yet been applied to subsidence monitoring in Wuhan city. This study explores the application of SBAS-InSAR method with high-resolution Radarsat-2 images to long-term monitoring of land subsidence in Wuhan city, and the cause of land subsidence. Speciﬁcally, (i) we investigate the potentials of 20 Radarsat-2 images acquired between 17 October 2015 and 3 June 2018 to derive land subsidence rates in Wuhan city. 
 The dashed lines are plotted by summing the Rayleigh  cross section of Eq. (13.17) over unit volume and substituting Eq. (13.21) to give  where f is the radar frequency in GHz and r the rainfall rate in mm/h. 
 (After Diamond.76)INFINITE 5x5 (23)5x9 (41) 10x10(95) DIMENSIONSINWAVELENGTHSRELATIVE POWER (48) cot B . CHAPTER 8 AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION G. V. 
 The symbology (such as the small circles, squares, and half circles),  represent the disposition of various forces such as ships and, aircraft. The multiple  elliptical and fan-shaped shaded areas correspond to a certain radar probability of  detection of various targets by various operational radars. For example, the small fan- shaped shaded area in the upper-right corner of the display represents the area where  a ground-based radar would be able to detect (with a certain probability of detection)  a particular aircraft target. 
 70. J. P. 
 TARGET FIG. 17.4 Sidelobe clutter-clear regions versus target aspect angle. aspect out to 60° on either side of the target's velocity vector. 
 MRWS is typically a medium-PRF waveform with range and dop - pler ambiguities. Doppler is used for clutter mitigation in each look, and the doppler  ambiguity may not need to be resolved since the tracker can determine range rate from  successive dwells. A typical MRWS M-of-N correlation would be three detections out  of eight looks (i.e., m = 3 and n = 8). 
 pp. 515-529. July, 1970. 
 COMBINED AND ISOLATED FROM ONE ANOTHER THROUGH THE USE OF MICROWAVE COMBINING AND ISOLATING TECHNIQUES $RIVE POWER FOR THIS PARALLEL GROUP IS OBTAINED FROM DRIVER OR PREDRIVER STAGES  USING PHASE 
 The requirements for detection do not place any demands on the shape of the  transmitted waveform except ( 1) that it be possible to achieve with practical radar transmit­ ters, and (2) that it is possible to construct the proper matched filter, or a reasonable approxi­ mation thereto. The maximum value or the ambiguity function occurs at T,r = 0,/, = 0 and is  equal to (2E)2• Thus the value lx(O, 0)12 is an indication or the detection capabilities or the  radar. Since the plot or the ambiguity function is orten normalized so that I x(O, 0) 12 = 1, the  ambiguity diagram is seldom used to assess the detection capabilities of the waveform. 
 If  high voltage is applied without RF drive, the amplifier appears as an open circuit to the  modulator, causing the modulator voltage to double. The higher voltage could lead to arcing.  The d-c high-voltage can be applied before the RF signal if the design is such that voltage  breakdown or arcing does not occur.. 
 Each of these has its advantages and disadvantages, which are discussed in Chap. 6. A trans-  mitter which consists of a stable low-power oscillator followed by a power amplifier is  sometimes called MOPA, which stands for master-oscillator power amplifier. 
 TRACKING GATES 4HE ANGLE LOCA 
 The problem isattacked inthree ways: (1)themagnetron isdesigned sothat itsfrequency change with changing r-floading issmalI; (2)the variations inr-floading arereduced bycareful design and construction ofther-fcomponents; (3)theradar receiver ismade insensitive tochanges infrequency bymaking itspass band broad orbyincorporating autoxriatic frequency control. Itisthe purpose ofthis subsection todiscuss only thefirst ofthese methods ofattack, that is,magnetron design. The effect ofloading onthe frequency ofamagnetron isusually expressed bywhat iscalled thepulling jigure,which isdefined asthetotal frequency excursion whichresultswhen astanding-wave ratioof1.5involtage. 
 Bamler, “The shuttle topography mission—a new class of  digital elevation models acquired by spaceborne radar,” Photogrammetry and Remote Sensing ,  vol. 57, pp. 241–262, 2003. 
 BEAM DIRECTION   -ULTIPATH DELAY  OFTEN EXPRESSED IN TERMS OF DELAY 
 SCATTERING ELEMENTS ARE CUT TO RESPOND TO A BROAD SPECTRUM OF RADAR FREQUENCIES 7EATHER CLUTTER AND CHAFF DIFFER FROM GROUND CLUTTER IN THAT BOTH THE MEAN DOPPLER SHIFT AND THE SPREAD ARE DETERMINED BY WIND VELOCITY AND WIND SHEAR  THE LAT 
 The interferometer consisted of four linear  horizontally oriented arrays. or sticks, with one stick mounted below the 2D radar antenna  and the other three sticks mounted above.  The elevation beamwidths of each of the individual antennas of the interferometer are  generally hroad so that multipath due to ground reOections can cause errors. 
 T?ffD tf Δt fB+ fD tfB- fDtransmit signal receive signal IF-signalf1f2   Ä     Figure 7.8  Triangular modulation with superimpo sed Doppler.  Doppler frequency = fD,  beat frequency = fB, frequency pass = B, period duration =T.   Both pieces of information, range and velocity, can be simple separated after the determin a- tion of f1/f2 from the IF signal. 
 MENT FACTOR THAT THIS IMPOSES ON A SIGNAL REACHING THE FULL EXCURSION OF THE PHASE DETEC 
  3PIRIT "OMBER  .ORTHROP  THE PRIME CONTRACTOR FOR THE " 
 CALLED BECAUSE A POINT  TARGET IS DISPLAYED IN THE IMAGE AS SOMEWHAT hSPREAD OUTv 4HIS 03& IS CHARACTERIZED BY A MAINLOBE AND  SIDELOBES IN BOTH RANGE AND CROSSRANGE 5SUALLY  WEIGHTING ALSO CALLED  TAPERING OR  APODIZATION  IS APPLIED IN THE PROCESSING  RESULTING IN CONSIDERABLY LOWER SIDE 
    
 Under certain con- ditions an array of open-ended waveguides will perform as though a slow wave were propagating across the aperture. This effect has been analyzed and studied experimentally,71'72 and it has been shown that as the array is scanned, higher-order modes are excited in the waveguides. Even though these modes are cut off, they contribute to the active impedance. 
 SEARCH 273  MODE IS INTER 
 Some of these tech- niques are useful during transmission, while others operate in the reception phase. Additionally, some are active against main-beam jammers, and others pro- vide benefits against sidelobe jammers. Blanking or turning off the receiver while the radar is scanning across the az- imuth sector containing the jammer or reducing the scan sector covered are means to prevent the radar from looking at the jammer. 
 (It is this bias, plus the offset frequency  described below, which causes the factor of 2 to be inserted in Eq. (14.12).)  The signal received from a single scatterer will appear as a varying doppler-frequency due  to the relative motion as the antenna scans by. The_doppler frequency is initially of high value,  decreases to zero beat, and then increases again. 
 301-302, July, 1958.  60. Kellelier. 
 SURVEILLANCE RADARSSOME WERE OF VERY LARGE SIZE AND LONG RANGE  AND MOST WERE READILY TRANSPORTABLE )T IS INTERESTING TO NOTE THAT 6(& AIRBORNE INTERCEPT RADARS WERE WIDELY USED BY THE 'ERMANS IN 7ORLD 7AR )) &OR EXAMPLE  THE ,ICHTENSTEIN 3. 
 NOISE RATIO  3.  IS THAT REQUIRED IF ONLY ONE PULSE IS PRESENT )T HAS TO BE LARGE ENOUGH  TO OBTAIN THE REQUIRED PROBABILITY OF FALSE ALARM DUE TO NOISE CROSSING THE RECEIVER THRESHOLD  AND THE REQUIRED PROBABILITY OF DETECTION AS CAN BE FOUND IN VARIOUS RADAR TEXTS    2ADARS  HOWEVER  GENERALLY PROCESS MORE THAN ONE PULSE BEFORE MAKING A  DETECTION DECISION 7E ASSUME THE RADAR WAVEFORM IS A REPETITIVE SERIES OF RECTANGULAR 
 However, in one design, 31•32 the heat transfer problem was overcome by having the axially . 292 INTRODUCTION TO RADAR SYSTEMS  located garnet bar directly cooled by a low-loss liquid dielectric that was allowed to flow along  the surface of the garnet material. The flow was confined by completely encapsulating the  garnet in a tefton jacket. 
 SUN 
 There is considerable transport delay in most SAR and  DBS processing; as a result, processed returns must be rectified (i.e., compensated for  geometric distortion), motion compensated, and mapped into the proper space angle  and range position. Since DBS usually maps a large area to provide overall ground  situational awareness, the total range coverage is often covered in multiple elevation  beams and range swaths. This is transparent to the operator but requires different  PRFs, pulsewidths, filter shapes, and dwell times.FIGURE 5.33  DBS processing ( adapted8; courtesy SciTech Publishing ) ch05.indd   35 12/17/07   1:27:15 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Radar fences, properly located, can mask the surface-reflected signal from the  near-in elevation sidelobes, but they are of limited utility when the main beam illuminates the  top edge of the fence and creates diffracted energy.53 Vertical polarization, often used in  trackers, reduces the surface-reflected signal in the vicinity of the Brewster angle, but has no  special advantage at low angles (less than 1.5" over water and 3" over land).45 For a similar  reason, circular polarization lias no inherent advantage in improving multipath below eleva-  tion angles corresponditig to tlie Brewster angle.  ?'lie hasic reason for poor tracking at low angle results from the fact that the conventional  ttacki~ig radar with a two-liorti feed in elevation (or its equivalent for a conical-scan tracker)  provides unambiguous information for only one target. At low elevation angles two'' targets"  arc present. 
 16, pp. 1351–1363, 1999. 68. 
 AES–36, no. 1, pp. 132–150, 2000. 
 47-50, November 1975. Reprinted in Barton, D. K.: "CW and Doppler Radars," vol. 
 NOISE RATIO  WHILE MINIMIZING THE DEVIATION BETWEEN THE ORIGINAL ELEMENT WEIGHTS AND THE PERTURBED ELEMENT WEIGHTS  &ULL AMPLITUDE AND  PHASE CONTROL AT EACH ELEMENT ENSURES THAT THE PERTURBED ANTENNA PATTERN HAS NULLS IN THE DESIRED DIRECTIONS WITH MINIMALLY PERTURBED WEIGHTS  (OWEVER  PHASE 
 Patent 3,815,132, 6/4/1974. 87. H. 
 In this  case, the most appropriate “theory of the experiment” is the time-domain formalism  described above. Other ways of viewing sea clutter in terms of surface geometry characterize the sea  and the clutter as fractal processes,115 or seek parameters describing its complexity by  defining a “strange attractor.”116 Unfortunately, these studies do not seem to contain  any useful insights into the physical scattering processes at the surface, except, per - haps, to conclude that sea clutter arises from multiple sources, which we already know.  On the other hand, the identification of changes in the characteristic measures  of these  processes (e.g., fractal dimension and embedding dimension) have been proposed as a  way to identify the presence of targets in clutter.FIGURE 15.22  (a) Measured slope (top curve) over a sampled surface in the Gulf Stream,112 with the cor - responding square of the surface curvature below; ( b) Wave-tank measurement of radar scattering from an  evolving breaking wave, correlated with wave surface height variations ( from M. 
 Dippy (who also gave his name to the Dippy oscillator, an important radar circuit), with the Seip of ©: C.E. Bellringer, Oboe, the companion long-  . THE DISCOVERY OF RADAR 29  range radar navigational aid, was the work of F. 
 However, inradar receivers higher powers are permissible solong as reasonable efficiency ismaintained. One ofthesimplest and most com- IBartelink et.al.,“Flat Response Single Tuned I-fAmplifier,” GEReport, hfay 8, 1943. 2A.J.Ferguson, “The Theory ofI-fAmplifier with Negative Feedback,” Cana- dian National Research Council Radio Branch Report PRA-59. 
 Tl,e track-mai11te11a11ce function determines when new observations should be made on  existing tracks in order to update the entries in the track file: Track maintenance not only  cstahlishes when the next radar observation must be made, but takes the steps necessary to  obtain it. In performing this function it is often convenient to obtain the target position  estimate in radar coordinates. Radar errors can be readily handled in this coordinate system. 
 Themagnetic circuitis completed externally withatemperature-stable ferriteyoke.Fluxdriveisgenerally usedto controltheremanent magnetization. Thedual-mode phaseshifterisoflightweightandiscapableofhighaveragepowa.Italso hasagoodfigureofmerit.Itschieflimitation relativetothenonreciprocal toroidphaseshifteris itslongerswitching time,beingoftheorderofIOto20liS.Theswitching speedislimitedbythe shorted-turn effectofthethinmetallic filmcovering theferriterod. Otherferritephaseshifters. 
 RANGE INSTRUMENTATION RADARS ARE NORMALLY USED WITH A BEACON PULSE REPEATER  TO PROVIDE A POINT 
 No quiescent dc current is drawn while the device is not being driven, such as in the radar receive mode. Hence there is no power dissipation in the amplifier while the transmitter is operating in this mode. 2. 
 46 TRANSMITTERS  RATHER THAN OTHER TYPES OF GRID 
 It follows that the space-based environment offers an  attractive alternative: repeat-pass interferometry, originally suggested by Goldstein.46  If the pass-to-pass observations are separated in the vertical plane, then interferom - etry leads to relative terrain height estimation.47 If two observations have a time  delay corresponding to the repeat period of the orbit (typically 10 to 45 days), then  sub-wavelength movements (in the line-of-sight direction of the radar) may be mea - sured.48 The technique can be extended to multiple passes with proportionate increase  in the temporal baseline, leading to quite remarkable results. Repeat-pass techniques  are well suited to mapping topographic relief and to long-term coherent change detec - tion for mapping glacier movement or terrestrial subsidence. If shorter time scales  are of interest, to detect moving vehicles, for example (GMTI), then a shorter inter - ferometric baseline is required, which implies two (or more) SBRs in relatively tight  co-orbiting formation. 
 7.10 STABILIZATION OF ANTENNAS14  ·~  If the radar platform is unsteady, as when it is located on a ship or an aircraft, the antenna  pointing must be properly compensated for this undesired motion. Stabilization is the use of a  servomechanism to control the angular position of an antenna so as to compensate automati­ cally for changes in the angular position or the vehicle carrying the antenna. An antenna not  compensated for the angular motion of the platform will have degraded coverage. 
 WIDEBAND RADAR MEASUREMENTS OVER BARE AND SNOW 
 (24) Such independent processing makes inconsistent positions and number of non-zero coefﬁcients in the target vector ﬁnally reconstructed in each channel, which is not favorable for extraction of target scattering information. For the improved OMP algorithm, the multi-channel target scattering information is used to determine candidate vectors and solve the projection coefﬁcients of each channel in the same support set, so as to ensure the consistency of the position and number of non-zero coefﬁcients in target vector reconstructed in each channel. Setting of the preset threshold Thres is related to the noise level of the echo signal. 
 67. Provejsil, D. J., R. 
 THE 
 Ifwecompare Eq. (14) with Eq. (4), weseethat insignal strength forgiven transmitted power the beacon process enjoys the advantage ofafactor of4flJP/G+s. 
 Differential  heating of land and ocean surfaces produces vertical and horizontal wind circulations  that distribute the water vapor throughout the troposphere. The water vapor content  of the troposphere rapidly decreases with height. At an altitude of 1.5 kilometers, the  water vapor content is approximately half of the surface content. 
 & IN THE POST 
 CYCLE FREQUENCY 
 SITE REGION )T USES RANGE MULTILATERATION FROM FOUR RECEIVERS LOCATED WITHIN  KM OF THE TRANSMITTER TO TRACK LOW 
 TELS 100, Dec. 1, 1952. 30. 
 ch02.indd   40 12/20/07   1:44:41 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 R. Bamler and P. Hartl, “Synthetic aperture radar interferometry,” Inverse Problems , vol. 
 MENT  THE CLUTTER LEVEL HAS BEEN PLOTTED 4HE CLUTTER 
 Ifcontinuous rotation isused, rather than sector scanning, thesweep ]Thecircuit ofFig. 13.41 isnotsuited foracathode-ray tube using accelerating potentials ashigh asthose required foraB-scope with apersistent screen.. SEC.1314] B-SCOPE DESIGN 529 \. 
 ÊÊ -1**",/Ê 
 The operator measured r“ange byapointer onthe tube, azimuth byturning thp goniometer to give zero response from theecho. Shel then pressed abutton and the grid reference (Chap. 7)ofthetarget appeared onaboard. 
 Peters, L., Jr.: End-fire Echo Area of Long, Thin Bodies, I RE Trans., vol. AP-6, pp. 133 -139, January,  1958. 
 41, pp. 142 146,  Jnrtrrary, 1953.  71. 
 13, pp. 243-259,  May, 1953.  46. 
 Height finding techniques which can be used with the phase-scanned array include a variety of coherent simultaneous-lobing (monopulse-multipulse* and phase-interferometry) tech- niques, as well as amplitude comparison sequential-lobing techniques. The phased array radar is becoming more commonplace in the present-day military marketplace, owing to an ever-escalating target and threat environment and dy- namics. The AN/TPS-59 L-band radar is an example of a long-range transportable 3D tactical radar with phase scanning to steer the beam in elevation. 
 To allow for this, a loss factor may be introduced. This factor can vary  with the application, but lacking a better number, a loss of about 2 dB might be used as an  approximation.  Variations in the receiver noise figure over the operating band also are to be expected. 
 For example, when   a = 5º, sdr = 0.71, and scr = 16.2. Thus, the down-range error is slightly reduced but  the cross-range error is greatly increased, not unlike that of a radar using angle data to  establish cross-range accuracy. These examples also apply when ground-based multistatic sites attempt to mea - sure target altitude. 
 WAVE CIRCUITRY 4HESE FEATURES ARE SUSCEPTIBLE TO POTENTIAL SHORT 
 K. Barton, CW and Doppler Radars,  Section VI-1, V ol. 7. 
 TRAVEL BY BEACON £57  the distance between the beacon and the interrogator.  Such an estimate of distance is obtained, usually, in the  well-Known Type A display manner, with the beacon  and interrogator pulses showing along a straight-line  trace, the time interval between them being easily inter-  preted into distance.  Much of this beacon development arose out of IFF. 
 (13.3) and taking  ti = n2/OB 4B,h9 the clutter radar equation is  IIP,A,~' C = --  64R2 sin 4  The clutter power is seen to vary inversely as the square of the range. Equation (13.9) applies.  for example, to the signal received from the ground by a radar altimeter. 
 andR.Symons: WideBandHighPowerKlystrons. IRE WESCON COllI'.HI'cord. vol..I.pI.1.pp.101111.1959. 
 A second technique was designed for an experimental version of the FAA AHSR-I S-band air traffic control.11 The technique augmented the 2D surveillance aper- ture with a vertical receive-only line array of elements. Each beam of a vertical stack of horizontal fan beams was generated from the line array by combining energy coupled out of waveguide runs at the appropriate length from the element to produce a linear-phase gradient element to element. This produced a set of uni- formly illuminated beams, each time-delay-steered to the desired elevation. 
 However, on basic radar-based systems, IALA expects a 100 target track  capability and a plot extractor that can deal with more than 1,000 plots per rotation. On  an advanced system, more that 300 targets may have to be tracked with a possibility  of more than 5,000 plots per antenna revolution. APPENDIX THE EARLY DAYS OF CMR The use of commercial marine radar arose directly from the rapid development of  radar technology for military applications during World War II. 
 Conj. 011 Aeronaut. Electronics, 1958, pp. 
 Parallel-plate feeds. A folded pillbox antenna (Fig. 8.24 ), a parallel-plate horn, or other simi­ lar microwave device can be used to provide the power distribution to the antenna elements. 
 The result is that the electrons of  the velocity-modulated beam become "bunched," or density modulated, after traveling  through the drift space. If the interaction gap of the output cavity is placed at the point of  maximum hunching. power can be extracted from the density-modulated beam. 
 Weil, H., et al.: Scattering of Electromagnetic Waves by Spheres, University of Michigan, Radial. Lab. Stud. 
 Theendfirearrayisaspccialcaseofthelinearortheplanararraywhenthebeamis directed alongthcarray.End/irclineararrayshavenotbeenwidelyusedinradarapplications. TheyarclIsuallylimitcdtolowormedium gainssinceanendfirelinearantenna ofhighgain rCt.Juires anexcessively longarray.Smallendflrearraysaresometimes uscdastheradiating elcmcnts ofabroadsidc arrayifdirective elements arerequired. Lineararraysofendfire clements arealsocmployed aslow-silhouette antennas. 
 (7) Three sub-segments are subjected to the azimuth FFT to obtain three sub-view images, respectively. The center of sub- iimage is located at fd,i, and the position offset between sub- iimage and sub- jimage can be expressed as (8). Δfd,ij=fd,i−fd,j=edr/parenleftbig tac,i−tac,j/parenrightbig+3 2e3rd/parenleftBig t2 ac,i−t2 ac,j/parenrightBig . 
 (ILL    3EC    . "UTLER  h4HE MICROWAVE TUBE RELIABILITY PROBLEM v  -ICROWAVE  *  VOL   PP n    -ARCH   0 $ , 7ILLIAMS   #IVIL  MARINE  RADAR   ,ONDON )NSTITUTION OF %LECTRICAL %NGINEERS      3EC   - ) 3KOLNIK   )NTRODUCTION TO 2ADAR 3YSTEMS  RD %D  .EW 9ORK -C'RAW 
 R. Woodyard: Object Detecting and Locating System, LJ.S.  Patent 2,435,615, Feb. 
 23.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 A reciprocal but more complex and costly uplink mode uses a bistatic receiver  carried by the probe, collecting high power, Earth-transmitted command signals first  scattered off the planet’s surface and characterized by the receiver-centered oval of  Cassini. It has an ~30 dB greater link margin, which was first used for Mars Odyssey  and is planned for future probes. In both configurations, even though two legs of the  bistatic triangle are extraordinarily long ( >105 miles), the third leg is sufficiently short  (~10 miles) to produce strong echoes at the receiver.2 These piggyback bistatic radars have provided useful data in simple, inexpensive  surveys of planetary surface properties as a prelude to robotic or human exploration,  specifically centimeter- to meter-scale roughness and material densities in the top  few centimeters of regolith. 
 The other is the L-hand, 2(M) II~I air-rotltc  sirrveillance radar (ARSR), Fig. 14.10, that provides coverage bctwccn airports. Tahlc I4 I 1151b  the major characteristics of these two radars. 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .496x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 When two identical radars are combined by track fusion, the update rate for each  tracking process does not change, and so the lag does not change. However, the stan - dard deviation of the tracking errors due to measurement noise is reduced by the square  root of 2, allowing a larger gain to be selected (optimization more to the right of the  bathtub), reducing the lag. 
 CAVITY  MAGNETRON CAN HAVE  . POSSIBLE MODES 4HE  O  MODE OSCILLATES AT A SINGLE FREQUENCY   BUT THE OTHER MODES CAN OSCILLATE AT TWO DIFFERENT FREQUENCIES SO THAT THE MAGNETRON CAN OSCILLATE AT .    DIFFERENT FREQUENCIES  #OAXIAL -AGNETRON ,IFE  4HE POWER THAT CAN BE PRODUCED BY A MAGNETRON DEPENDS  ON ITS SIZE ! LARGER SIZE MEANS MORE RESONATORS  WHICH MAKES IT MORE DIFFICULT TO SEPARATE THE VARIOUS MODES OF OSCILLATION IN A CONVENTIONAL MAGNETRON 4HE COAXIAL MAGNETRON  HOWEVER  WITH STABILIZATION CONTROLLED BY THE OUTER CAVITY  PERMITS STABLE OPERATION WITH A LARGER NUMBER OF CAVITIES  AND THUS WITH GREATER POWER 4HE ANODE AND CATHODE STRUCTURES OF A COAXIAL MAGNETRON CAN ALSO BE BIGGER  WHICH FURTHER ALLOWS OPERATION AT HIGHER POWER 4HE LARGER STRUCTURES PERMIT MORE CONSERVATIVE DESIGN  WITH THE RESULT THAT IT HAS LONGER LIFE AND BETTER RELIABILITY THAN CONVENTIONAL MAGNETRONS  AS WELL AS MORE STABLE OPERATION 4HE OPERATING LIFE OF A COAXIAL MAGNETRON HAS BEEN SAID  TO BE BETWEEN   AND   HOURS  WHICH IS A FIVE 
 This corresponds to about 1.4 dB peaking of the closed-loop low-pass  characteristic. The resonant frequency of the antenna and servosystem structure (including the  structure foundation, which is a critical item) must be kept well above the bandwidth  of the servosystem, otherwise the system can oscillate at the resonant frequency.  A factor of at least 10 is desirable for the ratio of system resonance frequency to servo  bandwidth. 
 The work in [ 6] proposes an innovative SAR data focusing algorithm, which does not need the knowledge of neither nominal SAR system parameters, nor sensor attitude and trajectory information. The basic idea consists in estimating directly from the data the range and azimuth reference functions needed for SAR focusing, by exploiting, through Singular Value Decomposition, the inherent redundancy present in the SAR raw data. To ensure reliable parameter estimation, strong point scatterers are needed within the imaged scene. 
 The Cassegrain dual reflector antenna (Figure 12.23), derived from optical tele - scope designs, is the most prevalent dual reflector configuration. Figure 12.23 a shows  a small subreflector between the feed and parabolic main reflector. The feed illumi - nates the hyperboloidal subreflector, which in turn illuminates the paraboloidal main  reflector. 
 In a pulse doppler radar using digital signal processing, the A/D converters are  usually selected to have a dynamic range that meets or exceeds the usable dynamic  range set by the maximum clutter-to-noise ratio ( C/Nmax) and the system stability. The  peak dynamic range, defined as the maximum peak sinusoidal signal level relative to  the rms thermal-noise level that can be processed linearly, is related to the number of  amplitude bits in the A/D converter by  S NN maxlog[ ]  =− dB quantAD,amp noise202 1 10 a a   (4.6) where [ Smax/N]dB = maximum input peak sinusoidal level relative to rms noise, dB  NAD,amp  =  number of amplitude bits (not including sign bit) in the A/D  converter  [noise]quanta = rms thermal-noise voltage level at the A/D converter, quanta The rms thermal-noise voltage level at the A/D converter is given in terms of quanta .  A single quanta refers to a unit quantization level of the A/D converter. 
 3.1. The echo, after modest amplification, is shifted to an intermediate frequency by mixing with a local-oscillator (LO) frequency. More than one con- version step may be necessary to reach the final IF, generally between 0.1 and 100 MHz, without encountering serious image- or spurious-frequency problems in the mixing process. 
 AES-7, pp. 1123-1130, November, 1971. ·•  50. 
 SPREAD CLUTTER ! NUMBER OF PHENOMENA HAVE BEEN IGNORED IN THE PRECEDING DISCUSSION  THOUGH  THEIR EFFECTS CAN BE OBSERVED IN SOME SKYWAVE RADAR SYSTEMS 4HEY INCLUDE I  A VARIETY OF NONLINEAR PROCESSES THAT CAN OCCUR DURING IONOSPHERIC PROPAGATION   II  DELAYED  ECHOES  FOCUSING AT THE ANTIPODE  AND III  ROUND 
 MODULATION FROM NON 
 5.6, except that the sampling gates described here are  of infinitesimal width whereas they are usually of the order of a pulse width in range tracking.  Substituting the optimum gating signal into the expression for accuracy gives (Rel. 3,  Eq. 
 18-26, IEEE Catalog no. 74 CHO 934-0 NEREM.  65. 
 Consideration was given to high-power metric ASV (100 kW), a 50 cm ASV and a 10 cm ASV. It was eventually decided that the best approach was likely to be a 10 cm system, and work was initiated with Ferranti to develop a suitableradar [ 1], to be called ASV Mk. III. 
 Apulse recurrence frequency of350 or300, permitting range presentation to250 or300 miles, would have reduced R-very little, but thecharacteristics ofthe modulator chosen restricted v,to400. A value ofv,of350 or300 would bedesirable from thestandpoint ofindi- cator range presentation forafuture radar system ofthis general type, buttwo other factors favoring higher v,must beconsidered: 1.The limiting accuracy ofazimuth-angle determinations isapproxi- mately half ofthe angular separation between pulses. Ascan rate of360/see with aV,of400 gives anangular separation between pulses of0.09°. 
 ING AT THE ILLUMINATED PATCHES GIVING RISE TO VELOCITY ERRORS  TERRAIN SLOPE IS ESTIMATED AND USED TO CORRECT THE ESTIMATED VELOCITY &)'52%    0RECISION VELOCITY UPDATE  CONCEPT . x°Î{  2!$!2 (!.$"//+  ! +ALMAN FILTER A RECURSIVE FILTER THAT ADAPTIVELY COMBINES MODELS OF TARGET MEA 
 Ground-based PPI sets are usually employed forthe detection and plotting ofaircraft, either togive early warning ofenemy airactivity, or tocontrol friendly aircraft byradio instructions, orboth. Mounted on shore, such sets canalso beused forplotting ship traffic topermit warning and control, but this use issimply atwo-dimensional case ofthe same problem asthat involved inplotting aircraft. Inwartime, radar sets orishipboard must provide air-search and con- trol facilities, and inaddition must give adisplay ofsurface targets, to permit station-keeping information and pilotage innarrow waters under conditions ofpoor visibility. 
 The locations of many of these places are shown in chapter 4,ﬁgure 4.32. The performance of radars was also routinely tested against surfaced submarine targets (viewed either broadside or stern-on) and radar training buoys. The Chivenorbuoy was a 12 ton, 12 ft diameter buoy with a 6 ft diameter family of corner reﬂectors on top [ 3]. 
 May.1968. 93.Shelton, J.W.:FastFourier Transform andBUllerMatrices, Pro£'.IEEE,vol.56,p.350.MardI. 1968. 
 D., and L. J. Ginsberg: Continuous Zonal Coverage—A Generalized Anal- ysis, AIAA Pap. 
 Turnstile junc­ tions 7 achieve isolations as high as 40 to 60 dB.  The use of orthogonal polarizations for transmitting and receiving is limited to short­ range radars because of the relatively small amount of isolation that can be obtained.8  An important factor which limits the use of isolation devices with a common antenna is  the reflections produced in the transmission line by the antenna. The antenna can never be  perfectly matched to free space, and there will always be some transmitted signal reflected back  toward the receiver. 
 2004 ,42, 292–300. [ CrossRef ] 26. Andon, D.L.; Chavdar, N.M. 
 /"  )N THE S  -ARCUM APPLIED STATISTICAL DECISION THEORY TO RADAR AND LATER 3WERLING  EXTENDED THE WORK TO FLUCTUATING TARGETS 4HEY INVESTIGATED MANY OF THE STATISTICAL PROBLEMS ASSOCIATED WITH THE NONCOHERENT DETECTION OF TARGETS IN GAUSSIAN NOISE .OTE )F THE INPHASE AND QUADRATURE COMPONENTS ARE GAUSSIAN DISTRIBUTED  THE ENVE 
 (15.2) /GHz where fr is the PRF, in hertz; and/GHz is the transmitted frequency, in gigahertz. Note from the velocity response curve that the response to targets at velocities midway between the blind speeds is greater than the response for a normal re- ceiver. The abscissa of the velocity response curve can also be labeled in terms of FIG. 
 The other technique, rlensirj~ raper, is applicable to the design of either linear arrays or to  large planar arrays. Consider a uniform grid of possible element locations withequal spacing.  The aperture illunlination function that would nornlally be considered for a conventional  antenna is used as the model for determining the density of equal-amplitude elements. 
 These devices employ a  fast-wave structure, such as a smooth circular tube, * one where the phase velocity of the  electromagnetic wave is greater than the velocity of light. (With a slow-wave device,  the phase velocity is less than the velocity of light.) The diameter of the gyrotron circuit  can be many wavelengths, and the electron beam need not be placed close to delicate  RF structures. Because a fast-wave structure rather than a slow-wave structure is used,  they do not have the size limitations of other microwave power sources as the frequency  is increased. 
 One of the requirements of the doppler-frequency amplifier in the simple  CW radar (Fig. 3.2) or the IF amplifier of the sideband superheterodyne (Fig. 3.4) is that it be  wide enough to pass the expected range of doppler frequencies. 
 This is of primary concern in look-down tail- chase air-to-air engagements. One additional important factor must be noted. Although the target signal can be discriminated from the feedthrough and clutter on the basis of frequency (ex- cept for the receding target in sidelobe clutter), this is only true for spectrally pure signals. 
 14.7  Scanning and Target Properties  .........................  14.7  14.4 Sources  ..................................................................  14.8  Master Oscillator Power Amplifier (MOPA)  Chains  ............................................................. 
 45. Brown, N. J.: Control and Protection Devices, IEEE NEREM 74 Record, pr 4: Radar Systems and  Components, Oct. 
 37. L. M. 
 The radio wave,  being similar to light (only much longer in wavelength),  is reflected in a more well-defined manner than if a  pencil of light from a searchlight were to strike the air-  craft and send a reflection back to the ground.  if we had some special sort of electric stop-watch, and  ‘timed the echo, we might find, for the sake of example,  that the echo came back to us, faint but accurately, in  weeth part of a second. That is the fofal time taken for  the radio wave to leave our aerial, traverse space, hit the  ainceait, and be reflected back through a receiving aerial  We-can easily see from this that the total distance out:  . 
 13. V. Bazin, J. 
 The element tij of the matrix is  defined either as wi if the i-th elementary radiator belongs to the j-th sub-array or as 0 if the i-th elementary radiator  does not belong to the j-th sub-array, where wi is the tapering weight in the analogue layer of Figure 24.8.FIGURE 24.8  Example of a ULA with sub-arrays that generate sum and difference channelsj Sub-array 1  formation Digital tapering for sum beam formation. .1 8 Sub-array 2  formation. .9 1 2 Sub-array 3  formation. 
 9.14 and 9.28) oraperforated sheet (Fig. 9.13). Fortunately such perforation does not impair the electrical performance ifthe holes arenot larger than about one-eighth wavelength inthe direction ofthe magnetic vector. 
 The increase in effective width  can sometimes be reduced by adding capacitive loading, which can constrain the effec - tive width to about a quarter wavelength wider than the physical width. The effective  E-plane dimension is the same as the actual dimension. Gain Optimization. 
  
 Ci.. and R. J. 
 Arm_v Missile Command, Redstone Arsenal, Alabama, Tedmical  Rer.ort RR-77-3. November, 1976. (Distribution unlimited.)  88. 
 RADAR TRANSMITI"ERS 2 (J  requires 50 kW of drive power an<l operates with 30 kV anode voltage and 70 A of peak anode  current. Liquid cooling is employed for both the anode and cathode. Approximately one  gallon of water per minute with a pressure drop of 9 psi is required. 
 LIKE PULSE COMPRESSION SIDELOBES AND THE DURATION OF THE  UNCOMPRESSED PULSE DICTATE HOW EFFECTIVE A PULSE 
 As shown in Figure 13a, the IMAM method can estimate the spatially-variant Doppler rate, and the estimation result is basically consistent with the EMAM method; while the EMAM method can further estimate the spatially-variant derivative of the Doppler rate as shown in Figure 13b. (a) (b)   'HULYDWLYHRI'RSSOHUUDWH +]  Figure 13. The estimation curves of the spatially-variant Doppler parameters based on the different methods. 
 isthebeatfrequency dueonly tothetarget'srange.Iftherateofchangeofthecarrierfrequency isJo,thebeatfrequency is .2R.j,.=foT=-foc(3.10) Inanypractical CWradar,thefrequency cannotbecontinually changed inonedirection only.Periodicity inthemodulation isnecessary, asinthetriangular frequency-modulation waveform showninFig.3.10b.Themodulation neednotnecessarily betriangular; itcanbe sawtooth, sinusoidal', orsomeothershape.Theresulting beatfrequency asafunction oftimeis showninFig.3.10cfortriangular modulation. Thebeatnoteisofconstant frequency exceptat theturn-around region.Ifthefrequency ismodulated ataratefmoverarangei1f,thebeat frequency is i1f=4Rfm~f c(3.11) Thusthemeasurement ofthebeatfrequency determines therangeR. Ablockdiagram illustrating theprinciple oftheFM-CW radarisshowninFig.3.11.A portionofthetransmitter signalactsasthereference signalrequired toproduce thebeat frequency. 
 It also subtracts the output of the top pair from the output of the bottom  pair to sense any unbalance in the elevation direction. In addition, the circuitry adds  the output of all four horns for a sum signal for detection, monopulse processing,  and range tracking. The comparator shown in Figure 9.2 is the circuitry that performs the addition and  subtraction of the feed horn outputs to obtain monopulse sum and difference signals. 
 1460--1466, December, 1974.  87. Ewell. 
 Therequirements fordetection donotplaceanydemands ontheshapeofthe transmitted waveform ex.cept(1)thatitbepossible toachievewithpractical radartransmit­ ters,and(2)thatitispossibletoconstruct thepropermatched filter,orareasonable approxi­ mationthereto.Themax.imum valueoftheambiguity function occursatTil=0./4=0andis equalto(2E)2.ThusthevalueIx(O,0)12isanindication ofthedetection capabilities ofthe radar.Sincetheplotoftheambiguity function isortennormalized sothatIx(O,0)12=I,the ambiguity diagram isseldomusedtoassessthedetection capabilities ofthewaveform. Theaccuracy withwhichtherangeandthevelocitycanbemeasured byaparticular waveform depends onthewidthofthespike,centered atIx(O,0)12,alongthetimeandthe frequency axes.Theresolution isalsorelatedtothewidthofthecentralspike,butinorderto resolvetwocloselyspacedtargetsthecentralspikemustbeisolated.Itcannothaveanyhigh peaksnearbythatcanmaskanothertargetclosetothedesiredtarget.Awaveform thatyields goodresolution willalsoyieldgoodaccuracy, butthereverseisnotalwaysso.. A continuous waveform (a single pulse) produces an ambiguity diagram with a single  peak. 
 Inasense, this book specializes toradar thetechniques repotied more fully elsewhere intheSeries. Radar isavery simple subject, and nospecial mathematical, physical, orengineering background isneeded toread and understand this book. Because the book covers the entire field ofeffort ofthe Radiation Laboratory and theother wartime radar establishments, itscontributing authors aremore numerous than those listed formost other volumes of this series. 
 For low pulse repetition frequency (PRF) radars [e.g.,  200 to 500 pulses per second (pps)], this may not cause a problem. For example, if the  PRF is 200 pps (or Hz), the time between pulses is 500 µs. If the switching time for  the phase shifter is 10 µs, only 2% of the time is wasted and less than 1.0 nmi of mini - mum range is lost. 
 For example, consider an oscillator with single-sideband phase-noise spectral  density as shown in Figure 2.76. All oscillator noise contributions are assumed to be  combined into this one curve. The single-sideband noise is increased by 3 dB because  both sidebands affect system stability, and the power integration is only carried out  for positive frequencies and by an additional 3 dB because the oscillator introduces  noise in both the upconversion to the transmitted signal and in the receiver downcon - version process. 
 ING RADARS MAY TRACK THE NOISE JAMMER IN ANGLE 4RACKING A NOISE JAMMER IN ANGLE FROM TWO SPATIALLY SEPARATED RADARS PROVIDES ENOUGH INFORMATION TO LOCATE A JAMMER WITH SUFFICIENT ACCURACY ! MORE THREATENING %#- AGAINST TRACKING RADARS IS $%#- 4HESE THREATS REQUIRE  CONSIDERABLY LESS ENERGY THAN NOISE JAMMING A FEATURE PARTICULARLY IMPORTANT ON TACTI 
 TECHNOLOGY DEVELOPMENTS AND INTEROPERABILITY ISSUES v $EFENSE 3CIENCE AND  4ECHNOLOGY /RGANISATION 2EPORT  $34/ 
 In both cases, the input signal is the  complex envelope sequence as formed using either digital down-conversion or analog  FIGURE   8. 27 (a) Time-domain digital pulse compression processor and ( b) frequency-domain digital  pulse compression processorComple x Envelope Input SignalConvolution Compressed Pulse Reference Waveform Replica (a) (b)Comple x Envelope Input SignalDFTMultiply Reference Waveform ReplicaDFT with zero fillInverse DFTCompressed Pulse ch08.indd   29 12/20/07   12:50:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The surface-reflected signal is small so  that the antenna makes small oscillations about some mean position. At greater ranges (eleva­ tion angles less than about 0.8 beamwidth), where the an"tenna main beam illuminates the  s~rface, the interference between the direct and the reflected signals can result in large errors in  elevation angle. The angular excursions can be up (into the air) or down (into the ground). 
  /" - ! BISTATIC RADAR USES ANTENNAS AT SEPARATE SITES FOR TRANSMISSION AND RECEPTION 4HE  TRANSMITTER AND RECEIVER CAN BE  AND USUALLY ARE  LOCATED AT THOSE SITES TO MINIMIZE TRANSMISSION LINE LOSSES )N NEARLY ALL CASES OF BISTATIC OPERATION  ANTENNA SEPARATION IS SELECTED TO ACHIEVE SOME OPERATIONAL  TECHNICAL  OR COST BENEFIT  AND IS USUALLY A SIGNIFICANT FRACTION OF THE TARGET RANGE  "ISTATIC RADARS HAVE BEEN DESIGNED  DEVEL 
 Thislimitstheabilityofcircular polarization toreject precipitation clutter. Therejection ofrainechoesbyacircularly polarized radardepends onthepuritywith whichcircular polarization canbegenerated byapractical antenna. aswellasthedeviation oftheprecipitation particles fromaspherical shape.!!7 Thecancellation oftheorthogonal polarization byanexceptionally well-designed, well-maintained antenna mightbelimitedto about40dB.79Toachieve 40dBofcancellation thevoltageellipticity ratiooftheantenna (ratiooftheminoraxistothemajoraxisofthepolarization ellipse)mustbe0.99,adifficult valuetoachieve. 
 Thereisnosimpleformula orstep-by-step guideforthedesignofanair-surveillance radar.Oneplacetostart,however, iswiththeproperformoftheradarequation, alongwitha clearunderstanding ofthetasktobeaccomplished bytheradarandknowledge ofthecon­ straints imposed bytheenvironment. Quiteoftenthereismorethanonefactoraffecting the selection ofaparticular radarcharacteristic, andthesefactorsaresometimes conllicting. The designer mustthenmakesubjective judgments orevenarbitrary choices inordertoarriveat acompromise setofradarcharacteristics. 
 Wang, C.; Liu, L.; Chen, L.; Feng, J.; Zhao, H.-S. Improved TEC retrieval based on spaceborne PolSAR data. Radio Sci. 
 Decision & Control , December 7–9, 1977, pp. 508–514. 24. 
 Usually weshall beinterested inthesignal that isreturned when the target lies somewhere along the maximum ofthe radar beam, and we should then replace GbyG,. Itisinstructive toproceed then toelimi- nate GObymeans ofEq. (l), obtaining S=P(TA‘j2 47rR%2”(4a) Note that AZnow appears inthedenominator, while thenumerator con- tains thesquare ofthearea oftheantenna aperture. 
 The  short-duration, large-amplitude " spike " at the leading edge of the leakage pulse is the result of  the finite time required for the TR to ionize or break down. Typically, this time is of the order  of 10 nanoseconds. After the gas in the TR tube is ionized, the power leaking through the tube  is considerably reduced from the peak value of the spike. 
 RENT ONLY WHEN THE 2& VOLTAGE SWING ON THE INPUT EXCEEDS THE BUILT 
 S4 !S AN EXAMPLE  CONSIDER AN ARRAY OF  ELEMENTS WITH AN APERTURE  EFFICIENCY OF   RA    VV  AND RE    RAD 4HEN  S4             -33, 
 defined as the velocity of propagation in free space to that in the medium in question.  At microwave frequencies, the index of refraction ti for air which contains watcr vapor  isl 1.12  where p = barometric pressure, mbar (1 mm Hg = 1.3332 mbar)  e = partial pressure of water 'vapor, mbar  T = absolute temperature, K  The parameter N = (n - 1)106 is the "scaled-up" index of refraction and is called refrctctrt~rty.  It is often used in propagation work instead of n because it is a more convenient unit. 
 3%, 
 2010 ,9, 550–553. [ CrossRef ] 20. Donoho, D.L. 
 POLARIZATION  AND HIGH 
 1,4.SE(cP) maybefoundbyaddingvectorially; Jhecontribution fromthevariouscurrentelements con­ stituting theaperture. Themathematical summation ofallthecontributions fromthecurrent elements contained withintheaperture gives'thefieldintensity intermsofanintegral. This integralcannotbereadilyevaluated intheg~neralcase.However, approximations tothesolu­ tionmaybehadbydividing'the areaabouttheantenna aperture intothreeregionsasdeter­ minedbythemathematical approximations thatmustbemade.Thedemarcations amongthese threeregionsarenotsharpandblend'oneintotheother. 
 .....726 17.15 AGround-to-ground Relay System 726 17.16 Relay System forAirborne Radar 732 INDEX .............. ..... .. 
 PLE +ALMAN RANDOM PERTURBATION MODEL &OR EXAMPLE  IN THE SIMPLIFIED CASE OF A SINGLE DIMENSION AND CONSTANT TRACKING CONDITIONS  THE MEASUREMENT COVARIANCE MATRIX IS SIMPLY A SINGLE  CONSTANT MEASUREMENT VARIANCE    K   R¼ M  AND THE TIME BETWEEN DETEC 
 58 Modulation from the latter source isatthe modulating frequency and low harmonics thereof. These spurious signals may begreatly reduced bytwo devices. First, one makes themixer ofFig. 
 In the case  of a ship’s surveillance radar, the antenna should be positioned as high as possible to  avoid shadowing by the superstructure, but the pedestal need not be stabilized since  stabilization can be achieved by electronic beam steering. Scanning can be in the form  of phase scanning or multiple simultaneous beams may be used on receive with a wide  antenna pattern on transmit. 13.2 ARRAY THEORY Array with Two Elements. 
 Pendleton: Tracking Radar, chap. 21 of" Radar Handbook,"  M. I. 
 QUENCY SHIFT  AND A NEGATIVE  D2DT CORRESPONDS TO AN INCOMING TARGET AND RESULTS IN A  POSITIVE DOPPLER FREQUENCY SHIFT #ONSIDER AN AIRBORNE RADAR WITH AN ISOTROPIC ANTENNA PATTERN  WITH CONSTANT VELOCITY  ALONG A STRAIGHT LINE PARALLEL TO A FLAT GROUND &IGURE  A  /N THE GROUND  THE CON 
 CALLED CLEAR CHANNELS SELECTED FOR RADAR OPERATIONS ARE CONTAMINATED WITH DIRECTIONAL NOISE OF NATURAL OR INDUSTRIAL ORIGIN  ALBEIT AT A MUCH LOWER LEVEL #ONVENTIONAL &&4 
 '(Z 3!2  THEY SHOWED THAT DIHEDRAL REFLECTORS LOOK QUITE DIFFERENT FROM TRIHEDRAL REFLECTORS IN FULLY 
 1964. 54.Peeler.G.D.M..andII.P.Coleman: Microwave Stepped-index Luneburg Lenses.IRETrails.. vol.AP-6.pp.2022U7.April.195R. 
 WAVE TANK v  * 'EOPHYS  2ES    VOL   NO #  PP n    % ! %RICSON  $ 2 ,YZENGA  AND $ 4 7ALKER  h2ADAR BACKSCATTER FROM STATIONARY BREAKING  WAVES v * 'EOPHYS 2ES  VOL   )SSUE #  P     9 ' 4ROKHIMOVSKI  h'RAVITYnCAPILLARY WAVE CURVATURE SPECTRUM AND MEAN 
 Voles, R.: New Approach to MTI Clutter Locking, Proc. IEE, vol. 120, pp. 
 TRACKING PROBLEMS  IT REDUCES TO A SIMPLE WEIGHTED SUM  $RRMP RMP PMP    
  
 CATIONS OF THE MATHEMATICAL EXPRESSIONS IN THESE FORMULATIONS .OTE THAT IN %Q  THE EXPRESSION IN THE BRACKETS UNDER THE INTEGRAL IS THE ONLY PLACE AT WHICH THE SURFACE 
 Ifitisassumed thatthenoisecontributions enterthereceiverviathemainbeamonly,the. Cosmic noise  rc Absorbing  atmosphere  Gtt Lat Antenna  'sidelobe and bock -lobe radiation GL  I I  Figure 12.12 Contributions to the total system effective noise temperat tire.  effect of the sidelobes may be neglected, and the total system effective noise iempcraturr. 
 There will always be a finite insertion loss, however, due to the  inherent losses in the directional couplers, phase shifters, and transmission lines that make up  the network./\ 16-element network at 900 MHz, for example, had an insertion loss of0.74 dB,  practically all of which was due to the strip transmission line used in the construction.87 In a  lossless, passive antenna radiating multiple beams from a common aperture it has been shown88  that the radiation pattern and the crossover level of adjacent beams cannot be specified  independently. With uniform illumination, as in the Butler array, the crossover level is 3.9 dB  helow the peak. This is independent of the beam position, element spacing, and wavelength. 
 That L-band system8 persists as the  design paradigm for Earth-observing space-based SARs. Seasat illustrates several  characteristics of many civilian Earth-observing SARs, including the size and aspect  ratio of the antenna (10.74 m by 2.1 m), its relatively steep angle of incidence ( ∼22°),  its swath width (100 km), and use of a linear FM (chirp) modulated pulse waveform  (634:1 compression ratio). Seasat SAR’s average radiated power was relatively small  (55 W) although its peak power was appreciable (1 kW). 
 Dennett. and L. S. 
 Distributed ISAR sub-image fusion of nonuniform rotating target based on matching Fourier transform. Sensors 2018 ,18, 1806. [ CrossRef ][PubMed ] 15. 
 CHANNEL SPOTLIGHT 3!2 THAT DWELLS ON A DESIGNATED GROUND 
 Weighting of the received signals, similar to the weighting of the aperture  illumination of a real antenna, is often applied to reduce the sidelobe levels.  Constraint on resolution and swath. Ambiguities can arise when signals are samyled, rather  than continuous. 
 SCATTERING 
 1312 appreciable sector ofthescan remote from the one ofinterest, inwhich case theswitching can beslower and insome cases mechanical. Inthe first case the index appears continuously, and inthe second itappears during anappreciable fraction ofthescan. Ineither event, theoperator isable tomake this setting while theindex ispresent. 
 THE 
 The precision of the range measurement is independent upon the pulse  duration so that there are no given restrictions here.  The resolution of two neighbouring ta r- gets, as has been shown in s ection 2.6, is calculated with the autocorrelation function and/or  with the cross- correlation.  Thus the resolution is directly dependent upon the pulse duration. 
 Performance of the Cross-Range Resolution in KA-DBS Assuming that the prediction factor is 0.5 in the proposed KA-DBS, then the CPI length in each azimuth angle can be estimated as: ˆTa=2NT r=2Ta (31) Now, the Doppler resolution in the proposed KA-DBS method is approximately given as: δˆfd=1 ˆTa=δfd 2(32) Since the equivalent number of pulse (i.e., the CPI length) is doubled in the proposed KA-DBS imaging algorithm, a ﬁner Doppler frequency resolution can be achieved. Therefore, the sharpening ratio in KA-DBS is given as: ˆKa=Δfd/δˆfd=2Ka (33) As illustrated in Equation (33), the sharpening ratio ˆKais theoretically improved by a factor of 2 compared to the conventional DBS imaging algorithm. Therefore, a high cross-range resolution and large sharpening ratio can be achieved in the proposed KA-DBS imaging framework. 
 The electron beam originates inahot cathode attheend ofthetube remote from thescreen. Intraversing thetube itisacted upon byanumber of electrostatic, orelectrostatic and magnetic, fields which serve tocontrol and focus it. The beam iscollimated and controlled inintensity bythe “control grid, ”apierced diaphragm immediately infront oftheflat oxide-coated cathode. 
 If a region illuminated at one time by a radar contains n scattering elements and the above criterion is satisfied so that power may be added, the radar equa- tion becomes " P1 jGti Arfjj = » PnGn AnWAA,-) A A, ' 1 (4^,2)2 ^ (4^-2)2 Here A A,- is an element of surface area, and Pti, Gn-, and An- are values of Pn Gn and Ar appropriate for an element at the location of A A/. The factor in parenthe- ses in the numerator of the right-hand expression is the incremental scattering cross section for element „ but this concept is meaningful only in an average. Thus the average power returned is given by . 
 In amplitude-only monopulse the purpose of phase detection is solely to tell on which half of the beam the target return is incident. The angle off boresight is then determined via table lookup of the ratio of the envelope-detected signal strengths. The primary disadvantage of this ap- proach is a degradation of accuracy at and near boresight relative to full-vector monopulse. 
 OF 
 Therefore the problem of non-Rayleigh statistics with its deleterious effect  on the false-alarm probability as occurs with high-resolution radar viewing sea clutter and  land clutter (Secs. 13.3 and 13.5), does not usually occur with precipitation clutter.  Moving target indication (MTI) radar can provide some improvement in the detection  of moving targets in precipitation if the MTI is properly designed to attenuate the doppler-  shifted precipitation echoes. 
 RESPONDING TO  P   n AND P   n  RESPECTIVELY  GIVING A    OR n POLARITY TO THE ANGLE 
 Figure 4.25. ASV Mk. VIC units [ 6]. 
 When L = O, RTRR = r2, which is the monostatic case where the ovals become circles. Operating Regions. Ovals of Cassini define three distinct operating regions for a bistatic radar: receiver-centered region, transmitter-centered region, and receiver-transmitter-centered region, or simply the cosite region. 
 If elevation scanning at high rates is required, as in height finders or  3-D radar. a fourth axis can be supplied as in (i). This configuration, although it requires no  computer. 
 It consists of two SAR images over the city of San Francisco that were acquired by ERS-2 C-band SAR sensor with VV polarization. The images were provided by the European Space Agency with a resolution of 25-m. These two images were captured in August 2003 and May 2004, respectively. 
 By using the antenna gain conventions stated ear- lier and a semi-isotropic sea directional spectrum, the value of crvv° was calcu- lated as -29 dB, and the measured values were grouped between -7 and +3 dB of this value over a 5- to 20-MHz-frequency span. This experiment provided a direct measure of the sea-surface scattering coefficient and has exposed charac- teristics that should be considered when using a° as a reference. Some other features need consideration. 
 TION ARE CALLED  DOPPLER RADARS 4HE DOPPLER EFFECT MANIFESTS ITSELF WHEN THERE IS   A RELATIVE RANGE RATE  OR RADIAL VELOCITY  BETWEEN THE RADAR AND THE TARGET 7HEN THE RADARS TRANSMIT SIGNAL IS REFLECTED FROM SUCH A TARGET  THE CARRIER FREQUENCY OF THE RETURN SIGNAL WILL BE SHIFTED !SSUMING A MONOSTATIC RADAR IE  COLLOCATED TRANSMIT 
 Two orthree tubes areused inseries, with avoltage divider across them toensure that thenetwork voltage isdivided equally among allthegaps before the pulse takes place. Triggering isaccomplished asshown in Fig. 10.39 bydepressing orraising quickly thevoltage ofthetwo middle electrodes. 
 10.31 and 10.33. 1001O. Line-type Pulsers.—A schematic diagram applicable tomost typical line type pulsers isshown inFig. 
 A hybrid detection algorithm based on energy and entropy analysis as an approach for spectrum sensing is considered in [ 9]. Principles of the pulsar navigation in the solar system are described in [ 10]. Sensors 2019 ,19, 3344; doi:10.3390 /s19153344 www.mdpi.com /journal/sensors 103. 
 FIGURE 18.7  History of precision orbit determination (POD) and intrin - sic instrument precision of the leading radar altimeters of the past 30 years.  Vertical axis in cm. Modern POD accuracy relies on GPS and the French  DORIS system. 
 TO 
 Ir x2 is replaced by w, where w represents power instead  of voltage (assuming the resistance is I ohm), Eq. (2.17) becomes  1 ( w) r(w) = --·-exp ----- wo Wo w;:::: 0 (2.18)  where "'o is the average power. This is the exponential probability-density function, but it is  sometimes called the Rayleigh-power probability-density function. 
 A. Weiss: A Switchable Circulator: S-band; Stripline; Remanent; 15  Kilowatts; JO Microseconds; Temperature Stable, IEEE Trans., vol. MTT-14, pp. 
    3EPTEMBER   * 2 &ORREST  'UEST EDITOR  SPECIAL ISSUE ON PHASED ARRAYS   0ROC )%%  ,ONDON   VOL   PT &   !UGUST    ( 3TEYSKAL  h$IGITAL BEAMFORMING ANTENNASAN INTRODUCTION v  -ICROWAVE *  VOL   PP n   *ANUARY   * , !LLEN  h! THEORETICAL LIMITATION ON THE FORMATION OF LOSSLESS MULTIPLE BEAMS IN LINEAR ARRAYS v  )2% 4RANS  VOL !0 
 Button. and L. M. 
 The image chips of the dataset are listed in Table 3. To conﬁrm the correctness of our methods, we also use the original image in validation dataset as our test dataset. The test datasets are listed in Table 4. 
 Minkler, CFAR: The Principles of Automatic Radar Detection in Clutter , Baltimore, MD:  Magellan Book Company, 1990. 24. R. 
 Missile midcourse guid - ance usually consists of assessing the missile performance, measurement of the target  and missile location, prediction of the path of each, and updating the resulting data to  the missile for the best future intercept of the target. It may also include the most current  estimate of the target type and attitude for best fuzing. The missile usually sends data  about its state of health, ownship measurements, remaining fuel amounts, and target  acquisition, if any.74 When the missile is close to the data link aircraft (which may or may  not be the launching platform), communication is often through an aperture other than in  the main MFAR. 
 The MAM methods can be implemented via either azimuth frequency-domain blocking [ 1] or time-domain blocking [ 22]. Speciﬁcally, the data are divided into several parts in azimuth in the time domain after multiplying the deramping function. Then, the azimuth fast Fourier transform (FFT) is carried out individually for each part to achieve multiple sub-view images. 
 REFLECTOR ANTENNAS  12.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 code portion of the SATCOM Workbench is based upon the legacy NEC-REF and  NEC-BSC codes. The EM Workbench, like GRASP, is very general in its capabili - ties, i.e., it can handle a diversity of reflector/scatterer shapes and combinations and  also has various feed models to draw upon. It also has feed and array wizards that  employ full-wave EM models that can be used as sources for reflector and scatter - ing design/analyses. 
 , $EFINITION OF 2#3  !N OBJECT EXPOSED TO AN ELECTROMAGNETIC WAVE DISPERSES  INCIDENT ENERGY IN ALL DIRECTIONS 4HIS SPATIAL DISTRIBUTION OF ENERGY IS CALLED  SCATTER 
 Apr. 3, 1975. Available from National Technical Information Service, Catalog  no. 
 The solid-state  transmitter provides low-power phase shift control for electronic steering followed by  power amplification in each of 18 channels. These are connected to the 18 elements  of the phased array through an 18-channel rotary coupler. The transmit/receive isola - tion on all 18 channels is provided through circulators. 
 6- 633 3     ARGMIN          QF QFQF ;= []   []B&B          WHERE -D IS THE DISTURBANCE COVARIANCE MATRIX   -D   SN ;)   *.2 s 3P*  E*  s  3P*  E* (=  DEPENDING ON THE ANGULAR COORDINATES OF THE JAMMING  P*  E* e AND ON THE  JAMMING 
 A large aperture collects more signal, but it also collects more jamming noise. The re- ceiver noise figure does not enter because it is assumed that the jamming noise is considerably larger than the receiver noise. Thus in a noisy environment one might not benefit from the effort to design a receiver with the ultimate in sensi- tivity. 
 AXIS TRACKING   DESCRIBED IN 3ECTION   IS A MEANS OF PLACING A COMPUTER IN THE TRACKING LOOP TO MINIMIZE LAG AND PROVIDE OPTIMUM ANGLE 
 Aslam, and M. C. Dobson, “Effects of vegetation cover on the radar sensitivity to  soil moisture,” University of Kansas, Remote Sensing Lab., TR 460-10, Lawrence, 1981. 
 Then we adjust our apparatus again and ‘black out?  one part of the line. The spot starts from the left,  travels to the right, stops, and instantaneously begins  its travel back. This is the part we suppress electrically. 
 Schuchman, “The contribution of wedge scattering to  the radar cross section of the ocean surface,” IEEE Trans . vol. GE-21, pp. 
 PATH BUT ALSO VIA MULTIPATH FROM THE UNDERLYING TERRAIN -ITIGATION TECHNIQUES HAVE BEEN FOCUSED ON ESTIMATING THE DIRECT JAMMER SIGNAL  ESTIMATING THE LINEAR SYSTEM CREATED BY THE MULTIPATH  AND REMOVING AN ESTIMATE OF THE REFLECTED JAMMER SIGNAL FROM THE MAIN RECEIVED RADAR SIGNAL  THIS  IS ALSO ALLOWED BY USING REFERENCE BEAMS POINTED AT HOT CLUTTER !DAPTIVE CANCELLA 
 KM SQUARE AREA AFTER ( ,EUNG ET AL    Ú )%%%  . 
 103.Richter.JH.,andD.R.Jensen: RadarCross-Section Measurements ofInsects.Proc.IEEE.vol.61. pp.143·144.January, 1913. 104.Glover, K.M.,K.R.Hardy,T.G.Konrad. 
 H. Doherty, D. T. 
 1972.  121. Baugh. 
 SIGNAL 
 A target at the edge of the time  window yields a frequency offset equal to one-half of the processing bandwidth:  B TtBp ∆ 2 2=   or  ∆t TB BB B Tp p= =( / ) (8.36) ch08.indd   34 12/20/07   12:51:13 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 
 8.30.  Several conclusions may be derived from the various stitdies of errors described above  and from Sec. 7.8. 
 TANCOS SIN   4HE  MINIMUM RECEIVE BEAMWIDTH  $P2 M REQUIRED TO CAPTURE ALL RETURNS FROM A  RANGE CELL INTERSECTING THE COMMON BEAM AREA IS APPROXIMATED BY    T A N    $$PS A P2M U 4 4 2 C2 2 y    WHERE SU IS THE UNCOMPRESSED PULSE WIDTH AND  $P4 IS THE TRANSMIT BEAMWIDTH 4HE  APPROXIMATION ASSUMES THAT RESPECTIVE RAYS FROM THE TRANSMIT AND RECEIVE BEAMS ARE  PARALLEL 4HE APPROXIMATION IS REASONABLE WHEN  24   22   , OR WHEN  ,  CSU  %QUATION  SHOWS THAT  $P2 M CHANGES AS THE RECEIVE BEAM SCANS OUT THE TRANSMIT  BEAM 0HASED ARRAY ANTENNAS OPERATING WITH A DIGITAL BEAMFORMER  CAN ACCOMMO 
 These radars were essentially copies of ASV Mk. II, except for changes to US types of ‘tubes ’[2] and were mainly ﬁtted to USN PBY Catalinas. With the advent of centimetric radars, the policy in the UK was mainly to use British ASV in British aircraft and only use American centimetric ASV in US aircraft. 
 Examples ofMechanical Scanners.-The above generalities will bemade more concrete inthe description ofafew specific scanners. These arechosen toillustrate avariety ofpurposes, shapes, and sizes. The SCR-584.—The antenna mount ofthe SCR-584 (Fig. 
 Therefore, selected systems and technology will be discussed. Several SBR sys- tems for rendezvous, earth exploration, and planetary exploration missions will be described. Systems considerations such as the space environment, orbit se- lection, radar tradeoffs, advantages and disadvantages, and critical issues will be discussed. 
 More vital performance characteristics generally dictate the choice of receiver front end: 1. Dynamic range and susceptibility to overload 2. Instantaneous bandwidth and tuning range 3. 
 TheCWradar,whenusedforshortormoderate ranges,ischaracterized bysimpler equipment thanapulseradar.Theamount ofpowerthat'canbeusedwithaCWradaris dependent ontheisolation thatcanbeachieved between thetransmitter andreceiversincethe transmitter noisethatfindsitswayintothereceiverlimitsthereceiversensitivity. (Thepulse radarhasnosimilarlimitation toitsmaximum rangebecause thetransmitter isnotoperative whenthereceiver isturnedon.) Perhaps oneofthegreatestshortcomings ofthesimpleCWradarisitsinability toobtain ameasurement ofrange.Thislimitation canbeovercome bymodulating theCWcarrier,asin thefrequency-modulated radardescribed inthenextsection. Someanti-air-warfare guidedmissilesystems employ semiactive homing guidance in whichareceiver inthemissilereceivesenergyfromthetarget,theenergyhavingbeentrans­ mittedfroman"illuminator" externaltothemissile.Theilluminator, forexample, mightbeat thelaunchplatform. 
 RANGE DOMAIN IS INVERSELY PROPORTIONAL TO THE ASPECT ANGLE WINDOW OVER WHICH THE  DATA ARE COLLECTED 4HUS  THE OPERATING CHARACTERISTICS OF THE INSTRUMENTATION SYSTEM  AND THE AZIMUTHAL DATA SAMPLING RATE MUST BE DECIDED BEFORE THE DATA ARE COLLECTED "ECAUSE THE CROSS 
 DEPENDENT    TRACKING ERRORS$YNAMIC LAG 'LINT $YNAMIC LAG VARIATION3CINTILLATION"EACON MODULATION 0ROPAGATION ERRORS !VERAGE REFRACTION OF     TROPOSPHERE!VERAGE REFRACTION OF    IONOSPHERE)RREGULARITIES IN TROPOSPHERIC    REFRACTION)RREGULARITIES IN IONOSPHERIC    REFRACTION !PPARENT OR    INSTRUMENTATION ERRORS    FOR OPTICAL REFERENCE 4ELESCOPE OR REFERENCE    INSTRUMENT STABILITY&ILM EMULSION AND BASE    STABILITY/PTICAL PARALLAX4ELESCOPE  CAMERA  OR REFERENCE    INSTRUMENT VIBRATION&ILM 
 the echoes from fa~r-weather clouds are usually of little concern.  It is also possible to obtain weak echoes from a deep, intense log at millimeter.  wavelengths, but at wavelengths of 3 cm and longer, eclioes due to fog may generally be  regarded as insignificant. 
 UNIT LINE WHERE THE  - 
 Metcalf  and  William C. Hahn , both from General Electric. This will be an important  component in radar units as an amplifier or an oscillator tube. 
 A useful  relationship is that the bisector of the bistatic angle is orthogonal to the tangent of that  ellipse at the target. The tangent is often a good approximation to an isorange contour  within the area common to the transmit and receive beams. When the bistatic radar’s receiving antenna is a phased array, and the array normal  is also normal to the baseline, qR is measured directly by the antenna in any bistatic  plane. 
 MENSURATE WITH THE RADIATED SPECTRUM AND HARDWARE LIMITATIONS AND WITH GOOD FREQUENCY AND IMPULSE RESPONSES ! WIDE TUNING RANGE PROVIDES FLEXIBILITY TO ESCAPE INTERFERENCE  BUT IF THE INTERFERENCE IS INTENTIONAL  AS IN THE CASE OF JAMMING  A CHANGE IN 2& FRE 
 (4.13)  and the diagram of Fig. 4.11 are similar in form to the phased array antenna as described in  Sec. 8.2. 
 fora2-phase, 120° for a3-phase synchro). Poten- tiometers cannot beused forrapid scans, since brush” chatter” becomes excessive and thelifeisexceedingly short. To fill this need, special variable condensers have been devel- oped. 
 Ali, I. Barnard, P. A. 
 TO 
 TOR MAY ENTER THE PATTERN ANGLE AND FACTOR DIRECTLY )N ADDITION TO ENTERING THE ANTENNA PATTERN DIRECTLY FROM THE KEYBOARD  !2%03 ALSO PROVIDES THE CAPABILITY OF IMPORTING AN ANTENNA PATTERN FROM AN !3#)) TEXT FILE THAT YOU MAY HAVE CREATED FROM ANOTHER APPLICATION !N EXAMPLE OF MULTIPLE UNITS IS THE TRANSMITTERS PEAK POWER 4HE DEFAULT UNIT FOR PEAK POWER IS +ILOWATTS "Y RIGHT 
 SENSING RADARS   PRIMARILY AS A RESULT OF THEIR PRACTICAL UTILITY -ANY APPLICATIONS ARE ENERGIZED BY RADARS NATURAL ABILITY TO OPERATE AT NIGHT OR THROUGH CLOUD  FOG  SMOKE  AND HAZE  AND ITS INHERENT SENSITIVITY TO CHANGES WITHIN THE SCENE AT WAVELENGTH SCALES 2ADAR IMAG 
 Although the ambiguity  diagram of the phase-coded pulse has a narrow spike, the wide plateau means that there can be  a large undesirable response from distributed clutter that extends in both the range and the  doppler domain, and the resolution performance will be poor in a dense-target environment or  when a small target is to be seen in the presence of much stronger echoes. EXTRACTION OF INFORMATION AND WAVEFORM DESIGN 431  A different phase-coded sequence can be assigned to each radar so that a number of  radars can share the same spectrum. In a military radar, the coding can be changed to help  counter repeater jammers that attempt to simulate the waveform. 
 The keep-alive can be replaced as a supplier of priming electrons in the TR by a radio-  active source, such as tritium, which produces low-energy-level beta rayss2 The tritium is  in compound form as a tritide film. The replacement of the keep-alive by radioactive tritium  eliminates the excess noise of the keep-alive and increases the life of the TR by an 'order of  magditude. Since a tritium TR needs no active voltages, a mechanical shutter is not required to  protect the receiver from nearby transmissions when the radar is turned off. 
 The system, asactually made and tested atthis same location, had 92-db attenuation atthe “infinite attenuation” points ofthe filters and experience showed that this was just comfortably adequate. From theabove results weconclude that the filters must have about 90dbofrejection for satisfactory operation atthis particular site. Measurements atother sites would bevaluable inanswering thequestion astohow representative this site is. 
 This single-site configuration is the familiar monostatic radar, and it greatly expanded the utility of radar, particularly for use by aircraft, ships, and mobile ground units. As a consequence bistatic radars became dormant. It was not until the early 1950s that interest in bistatic radars was revived for aircraft detection.1'2*"31 The United States AN/FPS-23 was designed as a gap- filler fence for the Distant Early Warning (DEW) line in the arctic. 
 Case 1 is where the radar and target speeds are equal and the target can be seen clear of sidelobe clutter in a head-on TARGET OR ANTENNA AZIMUTH (degrees) NOTE'- WIDTH OF ALTITUDE-LINE AND MAIN-BEAM CLUTTER REGIONS VARIES WITHCONDITIONS; AZIMUTH IS MEASURED FROM RADAR PLATFORM VELOCITY VECTORTO THE ANTENNA BORESIGHT OR TO THE LINE OF SIGHT TO THE TARGET;HORIZONTAL-MOTION CASE. FIG. 17.3 Clutter and clutter-free regions as a function of target velocity and azimuth.RADIAL OR LINE-OF-SIGHT COMPONENTOFTARGETVELOCITY(UNITS OF RADAR PLATFORMVELOCITY)(VT/VR)COSv/>T NOISE OR CLUTTER-FREE REGION (CLOSING VELOCITIES) MAIN-BEAMCLUTTER REGION ALTITUDE-LINE CLUTTERREGIONNOISE OR CLUTTER-FREE REGION (OPENING VELOCITIES) . 
 A binary code may be represented in any one of four allo - morphic forms, all of which have the same correlation characteristics. These forms are  the code itself, the inverted code (the code written in reverse order), the complemented  code (1s changed to 0s and 0s to 1s), and the inverted complemented code. For sym - metrical codes, the code and its inverse are identical. 
 Several simulator designs, results, and a complete discussion of the topic have been presented by Hannan and BaIfour.73 The technique is limited in that only discrete scan angles can be simulated. Several scan angles in both planes of scan give a general idea of the array impedance but may miss a large reflection of the type described in this section under "Mutual Coupling and Surface Waves." Nevertheless, the array simulator is the best method available for empirically de- termining the array impedance without building an array. (b) FIG. 
 Orbit Considerations.  Given an arbitrarily good radar altimeter, its orbit  becomes the dominant factor that may limit sea-surface height measurement accu - racy.79 Orbit selection for an ocean altimeter requires consideration of the impact of an  orbit’s inclination, repeat period, and altitude. For example, if the objective is absolute  sea-surface height accuracy over larger spatial scales and long time scales, then a  higher altitude orbit having a relatively moderate prograde inclination, and relatively  short non-sun-synchronous repeat period is the only sensible starting point. 
 The scale of probabil­ ity ranges from O to Lt An event which is certain is assigned the probability 1. An impossible  event is assigned the probability 0. The intermediate probabilities are assigned so that the  more likely an event, the greater is its probability. 
 Of the many  numerical ray-tracing codes developed over the years, the implementation by Jones  and Stephenson50 based on integration of the first-order Haselgrove equations remains  the most widely used. Coleman51 has developed an alternative implementation. ch20.indd   20 12/20/07   1:15:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Thus, many of the problems that occur with magne - trons when used in other applications are not found is this application. Also important  is that the civil marine radar business is very competitive because of the large world - wide need for such radars. This has resulted in the development of low-cost, highly  reliable magnetrons for this important radar application. 
 The projector unit consists ofa300-watt lamp and asimple optical system. The film iscooled byanairblast during projection. The maximum diameter of theprojected image is8ft,and images ofagiven point canberepeated on successive frames within acircle of~-in. 
 QUENCY IN WIDTH "Y THE USE OF A HIGH FIRST )&  ONE CAN ELIMINATE THE IMAGE PROBLEM  AND PROVIDE A WIDE TUNING BAND FREE OF SPURIOUS EFFECTS &ILTERING PRIOR TO THE MIXER REMAINS IMPORTANT  HOWEVER  BECAUSE THE NEIGHBORING SPURIOUS RESPONSES ARE OF RELA 
 TION OF AT LEAST  SATELLITES IN POLAR %ARTH ORBIT PROVIDING CONTINUOUS REFERENCE SIGNALS FOR DETERMINATION OF PRECISE POSITION AND VELOCITY  3LANT AND 'ROUND 0LANES  7HEN A 3!2 IMAGE IS INITIALLY PRODUCED  THE RANGE  PIXEL SIZE  CR IS USUALLY A CONSTANT )T IS GENERALLY CHOSEN TO BE SOMEWHAT LESS THAN  C"   EG   C"   TO ENSURE ADEQUATE SAMPLING  !S ILLUSTRATED IN &IGURE   THE ACTUAL GROUND LOCATIONS THAT CORRESPOND TO THESE RANGE SAMPLES ARE NOT SPACED AT CONSTANT INTERVALS IN GROUND RANGE .EAR THE SCENE CENTER  THEY ARE SPACED AT   C G   CR  COS X    WHERE X  IS THE GRAZING ANGLE !T GROUND RANGES CLOSER TO THE RADAR  THEY ARE SPACED STILL  FARTHER APART BECAUSE OF THE SPHERICAL RANGE CONTOURS .EAR THE SCENE CENTER  THE IMAGE  CORRESPONDS TO THE PROJECTION OF THE GROUND ONTO A  SLANT PLANE THIS PLANE IS DETERMINED  BY THE ,/3 AND ITS PERPENDICULAR IN THE GROUND PLANE 7E OFTEN REFER TO THIS TYPE OF IMAGE AS A  SLANT 
  P2      AND P4   
 Dynamotors.—To supply smaller radar sets with moderate power atnotover 1000 or1200 volts, adynamotor isoften more econom- ical inweight and efficiency than aninverter. Adynamotor has con- ventional d-cshunt- and series-field windings onthe stator and one or more armature windings onthe rotor. The rotor winding isexcited through brushes and acommutator from theinput voltage. 
 BEAM ANTENNAS  AND  SOME VARIATION OF -4$  ARE CURRENTLY USED ON MANY AIR 
 In the ordinary synthetic aperture radar the target is station-  ary and the radar is in motion. The opposite will also permit target imaging; that is, the radar is  stationary and the target is in motion. This is called inverse synthetic apertttre radar or delay-  doppler mapping. 
 This is a rather loosely defined term which is applied to any irreversible deterioration in the  detection or conversion properties of a crystal diode as the result or electrical overload. If  excessive RF energy is applied to the diode the heat generated cannot be dissipated properly  and the diode can be damaged. Excessive energy causes the diode to open-circuit or the  semiconductor to puncture, resulting in failure of the device. 
  
 If the noise at the input of the threshold detector were  truly gaussian, then no matter how high the threshold were set, there would always be a chance  that it would be exceeded by noise and appear as a false alarm. However, the probability  diminishes rapidly with increasing x, and for all practical purposes the probability of obtaining  an exceedingly high value of x _is negligibly small.  The Rayleigh probability-density function is aiso of special interest to the radar systems . 
 Rumsey, and T. E. Tice: On the Design of Arrays, Proc. 
 The blind speeds can be calculated: VB = *y *= ±0,1,2,... (15.1) where VB is the blind speed, in meters per second; \ is the transmitted wave- length, in meters; and/,, is the PRF, in hertz. A convenient set of units for this equation is 0.29/rVB(kn) = k- *= ±0,1,2,... 
 Althoilgh the first blind speed is greater in a two-frcqi~ency MTI, there may he deeper riiills  than one might desire in the doppler response cflaracteristic, just as tliere would be in a  staggered MTI with only two pulse repetition frequencies. The two-frequency MTI Itas the  advantage of being less sensitive than a single-frequency MTI to a mean clutter-doppler-  frequency other than dc, assuming the single-frequency MTI employs no compensation such  as TACCAR. This also results, however, in the loss of detection of targets with low doppler-  frequency shift that otherwise would have been detected with the single-frequency MTI. 
 MBs.  Direction of flight is obtained through the alt ae “Eng  along that: circle of constant range fom 0 ding Tthe  beacons which passes through the target lan — ad.  Ground speed is determined by measutilg : syste of  change from the other beacon, Accuracy oft ‘tho “no  depends on one curious factor, as a little cartfll MOUS Roth  will show: it depends on the position of tht ae or  landing-field relative to the two beacon station. 
 APERTURE PRODUCT  AND TYPICAL ANTENNA AND RADOME  INTEGRATED SIDELOBE RATIO IS SHOWN IN &IGURE  !T HIGH ALTITUDE AND NOSE 
 Ant. Prop., vol. AP-32, pp. 
 1966.  120. Wcip;~riti. 
 1957.  44. Rerger, F. 
 $     6J 6% TJ % T % E)1 D D        ¤ ¦¥³ µ´ COS   SIN   CO S VV $$ JJT JTDD%EVV ¤ ¦¥³ µ´ 
 PRISINGLY  ALSO AT THE -OON  A SPACE 
 No hot cathodes are required; therefore, there is no warmup delay, no wasted heater power, and virtually no limit on operating life. 2. Device operation occurs at much lower voltages; therefore, power supply voltages are on the order of volts rather than kilovolts. 
 FED DUAL  OFFSET REFLECTOR ANTENNA v )%%% !0 
 Ridgely, F. Fruge, and D. Cooke, “Stability measurement problems  and techniques for operational airborne pulse doppler radar,” IEEE Transactions on Aerospace  and Electronic Systems,  vol. 
 ArcSAR: Theory, Simulations, and Experimental Veriﬁcation. IEEE T rans. Microw. 
 Italso gives abetter receiver noise figure when used in,the first stage. A6J6 isused inthesecond stage because ofitslow plate-to- cathode capacity, animportant factor ingrounded-grid triode operation. The first two stages areoperated astriodes; inspite ofthehigh inter- mediate frequency and thebroad bandwidth, ani-fnoise figure of3.5db can usually beattained. 
 The amount of power that .can be used with a CW radar is  dependent on the isolation that can be achieved between the transmitter and receiver since the  transmitter noise that finds its way into the receiver limits the receiver sensitivity. (The pulse  radar has no similar limitation to its maximum range because the transmitter is not operative  when the receiver is turned on.)  Perhaps one of the greatest shortcomings of the simple CW radar is its inability to obtain  a measurement of range. This limitation can be overcome by modulating the CW carrier, as in  the frequency-modulated radar described in the next section. 
   
 Nar~~l Rrscur.i~lr  L~rl~or.utor.!~. Il'clslrirrgtorr. V.C.. 
 PULSE -4) CANCELER IMPLEMENTED AS A FINITE IMPULSE RESPONSE &)2  FILTER !S DISCUSSED IN 3ECTION   -4) CANCELERS USED IN PRACTICAL RADARS USE HIGHER 
 PULSE BASIS 4HE 3!2 DESCRIBED COULD  USING PULSE 
 Atmos. Ocean. Tech ., vol. 
 Thesecondintegral isnotaconstant. Theaposteriori probability canbewritten [2Tolp(SNIy)=kp(SN)expN~ty(t)s/(t)dt (10.28). IjETECTION OF RADAR SIGNALS IN NOISE 379  where the first and third integrals of Eq. 
 Owing totheerrors inthesystem and the variable delays intheplotting process, theinterpretation ofthe piles of disks interms ofaircraft was noteasy. Special officers known asfilterers stood beside the girls and decided, forexample, whether two adjscent tracks were really separate, orrepresented thesame aircraft, erroneously plotted byone ofthe stations. After hehad analyzed the data, the filterer put onthemap alittle plaque that bore hisbest estimate ofthe identity, position, height, speed, and number ofaircraft intheformation. 
 When thefeed isintheneighborhood ofthecross- over point (about ~ofthetime required forone complete scan) thesignal isambiguous because there aretwo beams. The parallel-plate assembly consists oftwo fabricated aluminum surfaces spaced ~in.apart, each consisting ofacast and machined center portion which supports aribbed sheet metal “wing” section above and below. Specially designed steel posts are used tohelp maintain the spailng between these surfaces without illeffect onthe electric waves. 
 TO 
 /-Ê" Ê /Ê* 
 40. Bussgang, J. J.: Sequential Methods in Radar Detection, Proc. 
 H. Mack: On Measuring the Radar Cross Sections of Ducks and Chickens,  Proc. IEEE. 
 1532–1533, September 1, 1994. 106. D. 
 \ . Theradarcrosssectionofatargetcanalsobereduced byelectromagnetic absorbent materials. SSOnetypeofelectromagnetic absorber isbasedondestructive interference. 
 W. Burlage: Design Procedure for Improving the Usable Bandwidth of an MTI  Radar Signal Processor. IEEE Co11/'ere11ce Record /976 International Conference 011 Acoustics, Speec/1. 
 But this is an  * Spprepeies time to reflect that what these scientists gave  . THE DISCOVERY OF RADAR 27  the world, under the stress and emotion of world war, |  was a series of discoveries each of terrifying potentialities,  and we must learn to harness them for peace.  But all this work of the pioneers was only a beginning. 
 Therearetwodifferent typesofcivilian air-surveillance radarsusedbytheFederal Aviation Administration forthecontrolofairtrafficinthelJnited States.OneistheS-band60nmiairport-surveillance radar(ASR),Fig.14.9,whichpr(\vides information onaircraft inthevicinityofairports. TheotheristheL-band, 200nmiair-roule surveillance radar(ARSR), Fig.14.10,thatprovides coverage between airports. Table14.1lists themajorcharacteristics ofthesetworadars. 
 Because a large antenna aperture produces a narrow antenna beamwidth, the  volume search function will require scanning a large number of beam positions. Naval ships need to operate in littoral (close to land) environments, as well as in  the open ocean. The desire to operate closer to land requires shipboard radars to have  the capability to reject high clutter returns. 
 Although theoperator must look through the screen itself atits10to20%reflection virtual image below, the real and virtual images can be distin- guished, providing the scales are nottoocomplex, bytheir positions t and usually byadifference inin-1 A tensity orappearance.I Display Projection.—An out- 1 t1 standing problem inthe use ofI B I radar forcontrol isthat oftrans-A 1 ferring radar plots from theface of— *. asmall indicator tube toalarge ‘A board where plotting canbedone,\\\\\\ other information entered, and aNonreflect!ng surface \\\ display visible tomany people in Wrtualimage alarge room presented. Tfis FIG.7.5.—Method ofplotting with theaidof problem has been approached inoptical superposition. 
 Radar System Engineering  Chapter 14 – Bibliography  167     15 Bibliography   15.1 Fundamental Literature   − Skolnik, M.; Introduction to Radar Systems, McGraw Hill Text; ISBN: 0072909803;  3rd edition (August 15, 2000)   − Detlefsen J.; Radartechnik; Springer -Verlag, 1989   − Skolnik, M.; Radar handbook; McGraw -Hill; 1990; UB -Ka [71A1195(2)]   − Baur, E.; Einführung in die Radartechnik; Teubner -Studienskripten ; 106: Elektr o- technik; UB -Ka [ 85A1809]  − Brookner E.; Radar Technology.; Artech House; 1988   − Barton, David K.; Radars (Band 1- 7); Artech House; 1977;  UB -Ka [ 80E84]  − Radar Handbook; McGraw- Hill, New York; ISBN 0 -07-057913- X  15.2 Automotive Radar   − J. Kehrbeck, E. Heidrich, W. 
 (2 51) 3  1 + 2 exp (- 5.55k2/t1;)  &= 1  For example, if we integrate 11 pulses, all lying uniformly between the 3-dR beamwidth, the  loss is 1.96 dB.  The beam-shape loss considered above was for, a beam shaped in one plant. only. 
 MARSIS is a multifrequency down-looking  radar that radiates 1-MHz pulses in one of four bands centered on the frequencies cited  in Table 18.9. Mars Express  is in an elliptical orbit; subsurface sounding operations  are restricted to the lower 250 km to 800 km altitudes. Sounding is further limited  by the ionosphere, which prevents effective radio wave propagation to the surface at  frequencies below the plasma frequency f0, which at Mars is ∼4 MHz on the sunlit side  and ∼1 MHz on the dark side. 
 The resolution cell is determined by the range-gate duration in the range dimension and by antenna beamwidth in the cross-range (azimuth) dimension. The resulting surface clutter return, even for rough seas and fairly severe ground reflections, will contribute much less energy than the target echo even when the target fills only a small por- tion of the resolution cell. Thus the angle information derived will be primarily from the target, because of its large contrast with respect to the clutter back- ground, and accurate homing can be achieved. 
   ANGLE SCANNING IN COMBINATION WITH MECHANICAL HORIZONTAL ROTATION FOR $ RADARS  ! CHAPTER IN THE FIRST EDITION OF THIS HANDBOOK WAS DEVOTED TO THIS APPROACH  WHICH SINCE THEN HAS RECEIVED MUCH LESS ATTENTION FREQUENCY IS TOO IMPORTANT A PARAMETER FOR ACHIEVING HIGH 
 Onstott, and S. P. Gogineni, “Towards identification of optimum  radar parameters for sea-ice monitoring,” J. 
 Oneorthefirstdevices toemploy circularly polarized wavespropagating in roundwaveguide wastheFoxphaseshifter.39Thisrotary-waveguide phaseshifterwasapplied inWorldWarIIbytheBellTelephone Laboratories intheFHMUSA,orMk8,scanning. radar.4.59 This was the first US radar to use a phased-array antenna with phase shifters to steer  the beam. The 42-element S-band array scanned a + 9 degree sector at a rate of 10 per second. 
 The frequency-versus-voltage characteristic of the backward-wave oscillator is exponential; all the others have a linear characteristic. If coherent operation of the VCO is required, the output signal must be phased-locked to a coherent reference signal. 10.6 PHASE-CODED WAVEFORMS Phase-coded waveforms differ from FM waveforms in that the pulse is subdi- vided into a number of subpulses. 
 $ TRANSMITTER AND CUSTOM RECEIVER  !LTHOUGH THIS PARTICULAR RADAR  IS NOT LIKELY TO BE THE PREFERRED DESIGN FOR A FUTURE WEATHER RADAR  THE /KLAHOMA 0HASED !RRAY 2ADAR TESTBED CAN BE USED TO EXPLORE ELECTRONIC SCANNING STRATEGIES TOGETHER WITH NEW PULSING AND PROCESSING CONCEPTS THAT MAY LEAD TO FUTURE DEVELOPMENT OF A PHASED ARRAY WEATHER RADAR SYSTEM !IRBORNE  2ADARS  7HEREAS COMMERCIAL AVIATION WEATHER RADARS ARE NOSE  MOUNTED 8 
 Editor, “Inside the Exocet: Flight of a sea skimmer,” Def. Electron ., vol. 14, pp. 
 Figure 3.7shows a photograph of an H 2S Mk. II installation in a Fortress (possibly H 2S Mk. IIB), with the various cables connected. 
 10.27  Paired Echoes and Weighting  ............................  10.27 Comparison of Weighting Functions  ...................  10.29 Taylor versus Cosine-Squared-Plus-Pedestal  Weighting  ........................................................ 
 Whenthediscovery ofthecavitymagnetron ledtothesuccessful development ofmicro­ waveradarearlyinWorldWarII,interestinlowerfrequency radarswaned.However, improve­ mentsinhigh-power, grid-controlled tubescontinued tobemadeduetotheneedsof UHF-TV, tropospheric-scatter communications, andparticleaccelerators aswellasradar.At VHFandUHF,grid-controlled powertubeshavebeenwidelyusedinhigh-power radar systems. Theyarecapable ofoperation atfrequencies ashighas1000to2000MHz,butthey donotseemtobecompetitive tothelinear-beam andcrossed-field microwave tubesatradar frequencies muchabove450MHz.Atlow-power levels,gridded tubesmustcompete withthe solid-state transistor. Thegrid-controlled tubeischaracterized asbeingcapableofhighpower,broadband, low ormoderate gain,goodefficiency, andinherent longlife.Unlikeothermicrowave tubes,the grid-controlled tubecanoperate, ifdesired, withalinearratherthanasaturated gaincharac­ teristic, Inatldition tobeingusedinhigh-power amplifier chains,thegrid-controlled tubehas alsoseenserviceinlargephased-array radarsthatoperate inthelowerradar-frequency bands. 
 14-16.  60. Jay, F. 
 Gabriel.56 Different methods for bearing estimation were described by Gabriel and, subsequently, by other authors.39'5 One is the maximum-entropy method (MEM). It works well with a Howells-Applebaum adaptive beamformer, which has an omnidirectional receiving pattern except where signals are present. The presence of signals is indicated by nulls in the receiving pattern. 
 Θ HB=83oλ a Gi=0,667 a24π λ2 a a 0510 15 20 25 30 35  0 0,05 0,1 0,15 0,2 0,25 Antennenabmessung a / m1520253035404550 Θ HBGi    Figure 13.14  Antenna parameters at 76 GHz, half -power bandwidth ΘHB, gain Gi, with cos2  alignment, and quadrature antenna (left ΘHB, right Gi).  13.3.2.3  System Paramter Overview   Kriterium  Spezifikation  Zielspezifikation   Angle range  ± 4° - ± 5°  ± 8°  Half-power beamwidth  3° 1°  Angle precision  0,2° – 0,5°   Angle resolution  0,1° - 0,25°    Beam switching  elektronisch  elektronisch   Field of range  2 m - 150 m 1 m – 250 m  Range precision  0,5 m oder 5%    Range resolution  0,05 m – 0,5 m 0,2 m  Velocit y range  ± 2 – ± 50 m/s 0 - ± 60 m/s  Velocity precision  0,25 - 0,4 m/s oder 5%   . Radar System Engineering  Chapter 12 – Selected Radar Applications  146     Velocity resolution  0,1 m/s – 0,2 m/s   Antenna size  8x8 cm2 bis10 x10  cm2   Bandwidth  > 100 MHz  > 300  MHz   Smallest target at 150  m 1 m2 1 m2  Reaction time  100 ms 30 ms  Interface  CAN      Table 13.1  Typical specification for an ACC sensor. 
 15.4. Historically,  comparisons of this type have been used often to provide support for the Bragg scat - tering hypothesis,102,104 and the agreement often looks good, especially for vertical  polarization at the higher wind speeds. Yet why this is so remains a puzzling curiosity. 
 In  brief, the most valuable outcomes that can be obtained with the RWS are radar range  calculation, radar elevation coverage diagrams in clear, ECM and multi-propagation  both for coherent and noncoherent radars; range and velocity responses in complex  ch24.indd   55 12/19/07   6:01:15 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 TO 
 As the distance gets greater, the primary MFAR aperture is used. As the  data link aircraft maneuvers, the aperture that has the largest projected area in the direc - tion of the missile is used. The bandwidth to the missile is very low and can be redundant  and highly encrypted to provide good antijam (A/J) protection. 
 76D-220, Final Rept. ER16-4414, Dec. 30, 1976. 
 2003 ,41, 939–947. 9. Xu, Z.W.; Wu, J.; Wu, Z.S. 
 The principles involved are illustrated inthe upper dia- gram ofFig. 13.10. By any of several methods afraction j3ofthe output signal issubtracted from the input signal ahead ofthe amdifier. 
 FIGURE 20.5  Comparison of measured vertical incidence ionograms  for a fixed time of day over a month with a model-based prediction of the  median, denoted by the small circles.600 400 200 01 Sounding frequency (MHz)2Altitude (km) 4 6 8 ch20.indd   16 12/20/07   1:15:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 
 Themagnetic field focuses,orconfines, theelectrons toarelatively long,thinbeam,andprevents thebeamfrom dispersing. Thebeamfocusing canbeprovided byauniform magnetic fieldgenerated bya longsolenoid whichhasironshielding aroundtheoutsidediameter. Cooling mighthavetobe provided fortheelectromagnets. 
 DOOR DEVICE FAILURES v  ,AS 6EGAS 2EVIEW *OURNAL    !UGUST     P ". È°£,>`>ÀÊ,iViÛiÀÃ  V >iÊ 
 COST 42 MODULES IS PARAMOUNT TO BEING ABLE TO EFFECTIVELY PRODUCE AFFORDABLE ARRAYS $ESIGN METHODOLOGIES  SUCH AS STATISTICAL PERFORMANCE . 
 By assuming that the target is small with respect to the pulse width and that the pulse  shape is known, the resolution capability can be improved by fitting the known pulse  shape to the received data and comparing the residue square error with a threshold.35   If only one target is present, the residue should be only noise and hence should be  small. If two or more targets are present, the residue will contain signal from the  remaining targets and should be large. The results of resolving two targets with   S/N = 20 dB are shown in Figure 7.23. 
 How far can this be pushed? Under the assumption that a target’s scattering is  coherent over a full 180 ° sector, it can be shown31 that the ultimate azimuth resolu - tion is l /4. By the way, such phenomenal results have been approached in the field  of seismology. Burst Mode.37 If average data rate is the driving consideration, then the integra - tion time TAz may be reduced below the canonical limit set by the azimuth antenna  beamwidth. 
 Digital control permits calibration of each attenuation value to determine the differ - ence between the actual attenuation and that commanded by injecting test signals  during dead time. In the past, gain controlled amplifiers were used extensively to control and adjust  receiver gain. Recently, this approach has largely been replaced using digital switched  or analog (voltage or current) controlled attenuators distributed throughout the receiver  chain. 
 CIES CLEARLY INCREASES THEIR VALUE $IFFERENT ANGLES OF INCIDENCE ARE MOST SUITABLE FOR DIFFERENT APPLICATIONS &OR EXAMPLE  SOIL MOISTURE MONITORING IS BEST WITHIN  OF VER 
 REGISTER GENERATOR .   05,3% #/-02%33)/. 2!$!2   n°£ -INIMUM 0EAK 3IDELOBE #ODES  "INARY CODES THAT PROVIDE MINIMUM PEAK TIME SIDE 
 HARRAP’S TORCH BOOKS  GENERAL Eprror: C. 
 No one  device seems to be sufficieritly uriiversal to meet the requirements of all applications.  Iri this text n device for obtaitiing ;t change of phase is called a pllase sl~ifier, but they have  also been kriowri ;IS l~/~r~\clr..\.  I~igitally switc11etI pl~asc sl~iftcrs. 
 Thefollowing describe thenominal performance capahilities thatmight beachieved withanover-the-horizon radaroperating intheHFband:Hl Rangecoverage-l000-4000 km;longerrangesarepossihle withmultihop propagation, but withdegraded performance. Anglecoverage--can be3600inazimuth fromasinglesite,ifdesired; 60to1200ismoretypical. Targets-aircraft, missiles, andships;alsonuclear explosions, prominent surface features (suchasmountains, cities,andislands), sea,aurora, meteors, andsatl:llitl:s.. 
 The transmitted and received electric polar- ization was in the plane swept out by the cone axis (horizontal polarization) for Fig. 11.9 and was perpendicular to that plane (vertical polarization) for Fig. 11.10. 
 The large attenuation of millimeter waves  propagating in the clear atmosphere sometimes can be employed to advantage in those special  cases where it is desired to reduce mutual interference or to minimize the probability of the  radar being intercepted by a hostile intercept (elint) receiver at long range.  I'he above attributes of the millimeter-wave region suggest as potential applications  low-angle tracking, interference-free radar, ECCM, cloud-physics radar, high-resolution radar.  fuzes, and missile guidance. 
 Skolnik, Introduction to Radar Systems , 3rd Ed., New York: McGraw-Hill Companies,  2001, Sec. 10.5. 29. 
 Theechoesfromclear-air turbulence arcquiteweakandareseenonlybyhigh-power radar.Thebasictheoryforscattering fromhomogeneous andisotropic turbulent mediawas firstgivenbyTatarski.III.112 Thescattering mechanism fromturbulent mediaissimilarto Braggscatterinthataradarofwavelength A.scattersfromthatparticular component ofthe turhulence witheddysizesequaltoA.12.Thevolumereflectivity, orradarcrosssection(m2)per cuhicvolume. fromaturbulent medium is (13.34) where C~.thestructure constant, represents ameasure oftheintensity oftherefractive-index fluctuations, andAistheradarwavelength. Ataltitudes ofseveralhundred meters.valuesofC; arcbetween 10qand10IIm"213,whichcorrespond toavolumeretlectivity ofabout 0.82x109toO.!Qx10IIm IatSband(A.=10cm).Thisisquitelowascanbeseenby comparison ofthevolumereflectivity forraininFig.13.12.At10kmaltitudeC;isapproxi­ mately10(4III2-'.I\nS-bandradarwithonedegreebeamwidth and1JISpUlsewidth viewingaturbulent medium with'I=10-10m-Iyieldsaradarcrosssectionat10kmof ahout3x10-4m2.Thus,angelechoesfrom.clear-air turbulence arenotlikelytobothermost radars. 
 Class-C C* : Energy storage capacitance for pulsed amplifiers C = I x dt where I = peak current dv dt = pulse length dv = pulse voltage droop FIG. 5.7 Block diagram of a high-power solid-state amplifier module for a corporate- combined transmitter.Collector Voltage Logic . operation is the preferred mode since the RF output power of the amplifier is maximized for a given prime power input.11'12 In general, the base-emitter junc- tion is reverse-biased, and collector current is drawn for less than half of an RF cycle. 
 4IME !DAPTIVE 0ROCESSING  ,ONDON  5+ )%% 2ADAR  3ONAR  AND .AVIGATION  3ERIES     * 2 'UERCI  3PACE 
 I.48  Index terms  Links   Transmitters (Continued)  1.3 4.1  spectrum control of 4.31  stability requirements for 4.25  traveling-wave tube 4.15 4.19  tube selection for 4.17  Twystron     4.17  Traveling-wave tubes (TWT) 4.15 4.19  Trilateration radar 24.1  Tropospheric absorption loss 2.47  Tropospheric propagation, and tracking radar 18.49  Two-pole filter 8.8  Twystron     4.17  Type II servosystem 18.25  U  UHF radar 1.14  Ultrasonic simulation of electromagnetic waves 12.26  Unfocused synthetic aperture radar 21.5  Universal Marcum curve 17.37  V  V-beam height finder 20.6  Vector monopulse 20.26  Vegetation, backscatter from 12.39 12.41  Velocity azimuth display (VAD) 23.22  Velocity-gate pull-off 9.26  VHP radar 1.14  Virga        23.8  Visibility factor 15.4  Visual detection 2.24  This page has been reformatted by Knovel to provide easier navigation. I.49  Index terms  Links   Voltage-controlled oscillator:  in pulse compression 10.15  in TACCAR 16.5  W  Wave spectrum of the sea 13.3  Weather attenuation 23.5  Weather radar ( see Meteorological radar)  Wedge, image of 11.42  Wedge model of sea clutter 13.33  Weighting in pulse compression 10.29  Wind, measurement of 23.22  Wind direction, effect of, on sea clutter 13.16  Wind profiler 23.27  Wind shear (microburst) 23.20  Wind speed, effect of, on sea clutter 13.8  Wire, radar cross section of 11.6 11.8  Wooden-round concept in missile testing 19.40    This page has been reformatted by Knovel to provide easier navigation. 
 818-820, November, 1970.  98. Cheston, T. 
 As mentioned in Section 4.3, In the experiment, the range sampling interval and azimuth sampling interval are Δf/prime=nΔf(n=1, 2,···,N)andΔθ/prime=mΔθ(m=1, 2,···,M)respectively. The test is adopted with stepped frequency signal, which features easy achievement of wideband and low requirements for hardware system. In order to make easier application of CS in the test, this paper adopts the deterministic sparsity observation approach based on Cat sequence for distance-oriented compressed sampling. 
 - -4) RADAR SYSTEM DESIGN ENCOMPASSES MUCH MORE THAN SIGNAL PROCESSOR DESIGN  4HE ENTIRE RADAR SYSTEMTRANSMITTER  ANTENNA  AND OPERATIONAL PARAMETERSMUST BE KEYED TO FUNCTION AS PART OF AN -4) RADAR &OR EXAMPLE  EXCELLENT -4) CONCEPTS WILL NOT PERFORM SATISFACTORILY UNLESS THE RADAR LOCAL OSCILLATOR IS EXTREMELY STABLE AND THE &)'52%  0ERFORMANCE OF PHASE 
 The largest maximum  amounts to approximately 5.7 dB, and the lowest minimum is nearly 4 dB under r 2π.  A sim- ple relationship is however here not stated.  The Radar backscattering cross- section is inde- pendent from the aspect angle, conditional upon the symmetry. 
 When the array is scanned, the influence of elements severalISOLATOR COUPLING AMPLITUDE AND PHASEAT ELEMENT OO WHEN ELEMENT 10 IS EXCITED WITH UNIT VOLTAGE AT 0° PHASE . wavelengths distant is also significant. For dipoles above a ground plane the mag- nitude of the coupling between elements decays rapidly with distance. 
 "-'%+*/1'& *)-#+2. .*1' #2*.&            5.%+*/1*-)#-&  20#&&+' 5%+*/1*-)#-&  20#&&+'//0.6 5%+*/1*-)#-&  20#&&+' 5%+*/1*-)#-&  20#&&+'  4'0+#/. {°{{  2!$!2 (!.$"//+  #&!2 ,OSS 4HIS LOSS IS CAUSED BY AN  IMPERFECT ESTIMATE OF THE DETECTION T HRESH 
 Therelativegainisalsocalledtheapertureefficiency [Eq.(7.9)]. Theaperture efficiency timesthephysical areaoftheaperture istheeffectiveaperture. Table7.1.Radiation-pattern characteristics produced byvariousaperture distributions A.=wavelength; a=aperture width Typeofdistribution,IzI<1 Uniform; A(z)=1 Cosine;A(z)=cos"(1tz/2): 1/=0 II=1 1/=2 1/=3 1/=4 Parabolic; A(z)=1-(1-~)Z2: ~=1.0 ~=0.8 ~=0.5 ~=o Triangular; A(z)=1-IzI Circular; A(z)=J1="? Cosine-squared pluspedestal; 0.33+0.66cos2(1tz/2) 0.08+0.92cos2(1tz/2),HammingRelative gain 1 0.810 0.667 0.575 0.515 1 0.994 0.970 0.833 0.75 0.865 0.88 0.74Half-power beamwiqth, deg 5U/a 5U/'1 69A./a 83A./a 95A./a 11U/a 51A./a 53A./a 56)./a 66)./a 73)./a 58.5)./a 63)./a 76.5)./aIntensity offirstsidclohc, dBbelowmaximum intensity 13.2 13.2 23 32 40 48 13.2 15.8 17.1 20.6 26.4 17.6 25.7 42.8. 
 Using the result of pixel-wise aspect entropy extraction, anisotropic pixels that belong to targets can be discriminated from isotropic clutters by thresholding. Next, we propose the aspect entropy extraction method at the target level. Thus, aspect entropy of targets can be extracted. 
 #/5.4%2-%!352%3   Ó{°xÎ 3UCH SOURCES CAN EXPECT GOOD PROPAGATION TO THE RADAR RECEIVER BECAUSE THE CHOICE OF  OPERATING FREQUENCY IS USUALLY OPTIMIZED FOR THE COVERAGE AREA )N THE CASE OF STAND 
 BAND RADAR USING AN !.&03 
 sincetheRFamplifiers atthattimehadagreaternoisefigurethanwhenthemixer alonewasemployed asthereceiver inputstage.TherearenowanumberofRFamplifiers that canprovide asuitable noisefigure.Figure9.4plotsnoisefigureasafunction offrequency for theseveralreceiver front-ends usedinradarapplications. Theparametric amplifier1o,lB has thelowestnoisefigureofthosedevicesdescribed here,especially atthehighermicrowave frequencies. However, itisgenerally morecomplex andexpensive compared totheother front-ends. 
 " SYSTEMS £Ó°{Ê , 
 There is H2S in its many forms, Gee, G-H, Oboe,  Babs, and Rebecca, and even that does not cover the  entire field. H2S-type systems, as previously described,  do not demand any co-operation from the ground, and  are virtually ‘television’ devices. Babs and kindred  systems take their name from the initials of “beam  approach beacon systems’ of aircraft guidance while  landing, and Rebecca systems again represent radar  beacons which do not transmit continuously, but  respond only to code inquiry. 
 10.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 The Radar Transmitter Thomas A. 
 ENTIAL REFLECTIVITY SIGNATURES IS EASILY EXPLAINED ,ARGE RAINDROPS ASSUME FLATTER SHAPES APPROXIMATED BY OBLATE SPHEROIDS  AS THEY FALL AND THUS SCATTER BACK THE HORIZON 
 AGE AREA 4HE PROCESSING TECHNIQUES USED TO GENERATE THE VARIOUS WEATHER IMAGES AND PRODUCTS ARE DISCUSSED LATER IN THIS CHAPTER &IGURE  SHOWS THE 3 
  D" IS USED TO PROVIDE A LOW  0&! DUE TO DISCRETES 4HE COMMON DISCRETE REQUIREMENT IS MADE  D" MORE STRINGENT  RELATIVE TO THE INDEPENDENT REQUIREMENT AS DISCUSSED ABOVE {°{Ê ,  
 Assuming that 115-volt output isdesired, theregulator can beadjusted toregulate at118to120 volts and enough resistance cut in,bymeans ofthe rheostat, sothat the voltage is115 volts atfull radar load with everything atnormal operating temperature. Under normal operating conditions, then, the regulator isallout and not functioning. Ifthe voltage should rise, as during warmup period orwhen the radar isonstand-by, the regulator will cutinwhen the voltage comes upto118 to120 volts and prevent further riseinvoltage. 
  
 Echoes from  fixed targets rernain constant throughout, but echoes from moving targets vary in amplitude  from sweep to sweep at a rate corresponding to the doppler frequency. The superposition of  ( c I  Figure 4.2 (a) RF echo pulse train; (h) video pulse train for doppler frequency f, > I/?; (c) video pulse  train for doppler freuqncy /, < I/T.  MTIANDPULSE DOPPLER RADAR103 NotethatEqs.(4.1)to(4.J)represent sine-wave carriers uponwhichthepulsemodulation is imposed. 
 "ASED 2ADAR (ANDBOOK  #HAPTER   .ORWOOD  -! !RTECH (OUSE    ! &ARINA AND & ! 3TUDER   2ADAR $ATA 0ROCESSING   6OL   !DVANCED 4OPICS AND !PPLICATIONS   5+ 2ESEARCH 3TUDIES 0RESS ,TD    ) 3TEIN  h"ISTATIC RADAR APPLICATIONS IN PASSIVE SYSTEMS v  *OURNAL OF %LECTRONIC $EFENSE       PP n  -ARCH   $ + "ARTON  -ODERN 2ADAR 3YSTEM !NALYSIS  .ORWOOD  -! !RTECH (OUSE    $ + "ARTON  PRIVATE COMMUNICATION  *UNE  2 , %ASTON AND * * &LEMING  h4HE .AVY SPACE SURVEILLANC E SYSTEM v  0ROC )2%  VOL    PP n     2 * ,EFEVRE  h"ISTATIC RADAR .EW APPLICATION FOR AN OLD TECHNIQUE v  7%3#/. #ONF 2EC  3AN  &RANCISCO    PP n  & , &LEMING AND . * 7ILLIS  h3ANCTUARY RADAR v  0ROC -IL -ICROWAVES #ONF   ,ONDON   /CTOBER n    PP n  , "OVINO  h"ISTATIC RADAR FOR WEAPONS LOCATION  v 53 !RMY #OMMUNICATIONS %LECTRONICS  #OMMAND  &ORT -ONMOUTH  .*    2USSIAS !RMS #ATALOG  VOL   !IR $EFENSE  -OSCOW -ILITARY 0ARADE ,TD   h"ARRIER v "ISTATICAL LOW FLYING TARGET DETECTION SYSTEM  .IZHNY .OVGOROD 3CIENTIFIC 
 Although isotropic elements are  not realizable in practice, they are a useful concept in array theory, especially for the computa­ tion of radiation patterns. The effect of practical elements with nonisotropic patterns will be  considered later. The array is shown as a receiving antenna for convenience, but because of the  reciprocity principle, the results obtained apply equaHy well to a transmitting antenna. 
 vol. 53. p. 
 WATT TRANSISTORS )N OTHER WORDS  MICROWAVE TRANSISTORS ARE MUCH MORE COST 
 A reduction in signal strength will  also occur if the target doppler shift is sufficiently large to be outside the passband of the  along-track-dimension processor. When the SAR is located on a satellite, the effect of earth  rotation must be properly compensated since it results in the earth's surface appearing as a  moving target.10•91  The difference in signal characteristics from a moving target as compared to that from a  stationary target can be used as a basis for combining AMT[ (airborne moving target indica­ tion) with SAR.8 The moving-target doppler shift can be detected when it exceeds the clutter  doppler-spectrum width. It is also possible to use a dual sidelooking antenna pattern and  detect the phase difference between the two mutually coherent observations of a target  separated in time. 
 WAVELENGTH RADAR FOR ESTIMATION OF  RAIN PROFILES v !DVANCES IN !TMOS 3CI  VOL   PP n     ' , 3TEPHENS  $ ' 6ANE  2 * "OAIN  ' ' -ACE  + 3A SSEN  : 7ANG  ! * )LLINGWORTH  % *  /#ONNOR    7 " 2OSSOW  3 , $URDEN  3 $ -ILLER  2 4 !USTIN  ! "ENEDETTI  # -ITRESCU  AND THE  #LOUD3AT 3CIENCE 4EAM  h4HE #LOUD3AT MISSION AND THE ! 
 NAL 
 3dB m−1two-way. The noise power, pn, in the receiver is given by =pk T F B (7.2)n 0n where kis Boltzmann ’s constant, T0is the standard temperature ( =×−kT 41 0 021J), Fnis the receiver noise ﬁgure and Bis the receiver bandwidth (Hz).Airborne Maritime Surveillance Radar, Volume 1 7-7. The power of the sea clutter return, C, is determined by ( 7.1) and the RCS of the clutter, σcat a given range given by σσ σθτ ϕ=≈ARc /2 cos(7.3) c00 az where σ0is the clutter re ﬂectivity per unit area and Ais the area illuminated by a pulse, determined approximately at range Rby the azimuth beamwidth θaz(radians) and the pulse length τc/2(m); ϕis the grazing angle. 
 STATE RECORDER TO BUFFER DATA OUTPUT FROM THE RADAR  AS WELL AS FROM THE REST OF THE PAYLOAD 0!,3!2S VOLUMINOUS VARIETY OF MODES IS A CURSE AS WELL AS A BLESSING -ISSION  MANAGEMENT MUST COPE WITH DATA COLLECTION IN EACH OF THESE MODES  AS WELL AS PHAS 
 Looking upwind, at target of 15 dB m2RCs is detectable from about 9 nmi range down to about 5 nmi range, but then is not detectable until a range of about 1 nmi. This type of behaviour may explain the observations by the operator in early trials [ 5] (see chapter 3) that sometimes the target would disappear over an interval from 4 or 5 miles range down to about 2 miles range, before reappearing again. The curves in these ﬁgures also give an indication of the range extent of sea returns. 
 87. A. E. 
 FIGURE   16. 41 Angular response of s 0 of dry snow at different  frequencies. Rapid falloff at lower frequencies apparently results from  penetration to the smooth ground surface. 
 FED ARRAY )T IS FREQUENCY 
 Lightweight Airborne Receiver. ~This receiver ispart ofa lightweight 3-cm airborne radar (AN/APS-10) intended primarily for navigation. Itwas designed torequire aminimum offield test equip- ment and aminimum number ofhighly trained service personnel. 
 ORIENTED REMOTE SENSING RADARS  TYPICAL COMBINATIONS INCLUDE (( AND (6  FOR EXAMPLE  OR (( AND 66 WHICH REQUIRES TWO SEPARATE TRANSMIT POLARIZATIONS  4HE !3!2 ABOARD %.6)3!4 IS THE FIRST SPACE 
 10. Dong, J. Pulsar navigation in the solar system. 
 Electronic beam-scanning phased array radars  may track multiple targets by sequentially dwelling upon and measuring each target  while excluding other echo or signal sources. Because of its narrow beamwidth, typically from a fraction of 1 ° to 1 or 2 °, tracking  radars usually depend upon information from a surveillance radar or other source of  target location to acquire the target, i.e., to place its beam on or in the vicinity of the  target before initiating a track. Scanning of the beam within a limited angle sector may  be needed to acquire the target within its beam and center the range-tracking gates on  the echo pulse prior to locking on the target or closing the tracking loops. 
    4RANSLATED  FROM THE 2USSIAN VERSION PUBLISHED BY -OSCOW 3OVIET 2ADIO 0UBLICATION (OUSE   . 
 RECEIVERS, DISPLAYS, AND DUPLEXERS 357  Resolution on the CRT is lirnited by the phosphor characteristics as well as the electron  beam. A double-layer phosphor will have poorer resolution that a single-layer phosphor.  Color CRTs. 
 The  prf's differ by about 20 percent. A typical rain spectrum with a nonzero average velocity is  depicted on the bottom line. (Precipitation at S band might typically have a spectral width of  about 25 to 30 knots centered anywhere from -60 to + 60 knots, depending on the wind  conditions and the antenna pointing.42) The narrow spectrum of the moving aircraft is at the  right of the figure. 
 Space-Surface Bistatic Synthetic Aperture Radar with GlobalNavigation Satellite System Transmitter of Opportunity—Experimental Results. IET Radar Sonar Navig. 2007 , 1, 447–458. 
 Any use is subject to the Terms of Use as given at the website. Ground Echo.  GROUND ECHO  16.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 from companies that supply that market. For  discussion of the relative merits of different  passive calibration targets, see Ulaby et al.86 The ideal receiver would respond linearly  to its input, so that a single calibration at  one input level would suffice for all levels. 
 COMPONENT HARMONIC LINE SIGNAL IN COLORED NOISE v IN  $EFENCE !PPLICATIONS OF 3IGNAL 0ROCESSING    $ ! #OCHRAN  " -ORAN  AND , 7HITE EDS   .EW 9ORK %LSEVIER    PP n  ' &ABRIZIO  , 3CHARF  ! &ARINA  AND - 4URLEY  h3HIP DE TECTION WITH (& SURFACE 
 These consist ofartificial video signals introduced into thedisplay byaprecision timing circuit; thus, inaccuracies inthedisplay donot enter assources oferror inthe measurements. Almost every display entails asetofdiscrete, regularly spaced markers derived from anoscillator properly phased with respect tothefiring ofthemodulator. Fairly accurate ranges can beread from these markers ataglance. 
 shows that the beamwidth eisthe full beamwidth athalf power. A small amount ofpo’wer isunavoidably radiated inundesired directions, forming the “side lobes’) shown inthis figure. 92. 
 This double use of the STALO  introduces a dependence on range of the clutter and exaggerates the effect of certain  unintentional phase-modulation components by 6 dB, the critical frequencies being  those which change phase by odd multiples of 180° during the time period between  transmission and reception of the clutter return from a specified range. ch06.indd   15 12/17/07   2:03:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 E. F. Ewing, “The applicability of bistatic radar to short range surveillance,” in IEE Conf. 
 FED SERIES   r¤ ¦¥³ µ´L LGBEAMWIDTH  r¤ ¦¥³ µ´L LGBEAMWIDTH #ENTER 
 NewYork.1970. JO.Collins. J.R..andT.F.Harwell: RASSRArrayComesofAge,Microwaves, vol.II,pp.36-42,August, 1972. 
 Oceanographers have not always been in complete agreement about the form of the frequency spectrum. Nonequilibrium wave conditions, inadequate sam- pling times, poor ground truth, etc., can contaminate the data set from which em- pirical spectra are derived. However, by careful selection of data from many sources, ensuring that only equilibrium (fully developed) sea conditions were rep- resented and the wind was always measured at the same reference height, Pierson and Moskowitz16 established an empirical spectrum that has proved pop- ular and useful. 
 FIG.6.S.—Distortion caused byD-scope display. the range and angle scales. Such adisplay, known asamicro-D, issimply asubstitute foraPPI sector; itisused either because itis technically easier toattain, orbecause thesame indicator isalter- natelyused foraregular type Bdisplay. 
 CHANNEL RADAR ARE GOING TO ADOPT FULLY DIGITAL  SOFTWARE CONTROLLED RECEIVERS  AS IN THE $!2 CASE HERE  THE EXPECTED ADVANTAGES ARE THE WIDER LINEAR DYNAMIC RANGE AND THE WITHIN 
 At these heights there can  appear at times patches of high-density ionization cai'led sporadic E whicll, wllen available,  can be quite effective in providing stab!e propagation. The multiple refracting regions give rise  'to multipath propagation which can result in degraded performance because of the s;rnulta-  neous arrival of radar energy at the target via more than one propagation path, each with -  different time delays. The effects of multipath can be reduced by the proper selection of  frequency and by use of narrow elevation beamwidths which allow the energy to travel to the  target via only a single path. 
 Byintroducing theapplied magnetic fieldfromwithinthewaveguide viathesingle-turn drivewire.theshorted-turn effectthatlimitstheswitching speedoftheReggia-Spenca phase shifteriseliminated. Thispermits switching timesoftheorderofmicroseconds. Whereas hysteresis wasanuisance tobetolerated intheReggia-Spencer device,thelatching phase shiftertakesadvantage ofthehysteresis looptoproduce thetwodiscrete valuesofphaseshift without theneedforcontinuous drivepower. 
 MISE SOLUTION IS SHOWN IN &IGURE C   WHERE ANALOG BEAMFORMING IS USED TO IMPLE 
 102. sensors Article Pulsar Emissions, Signal Modeling and Passive ISAR Imaging Andon Lazarov Department of Information Technologies, Naval Academy, 9026 Varna, Bulgaria; lazarov@bfu.bg; Tel.:+359-887-262-478 Received: 11 June 2019; Accepted: 29 July 2019; Published: 30 July 2019/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: The present work addresses pulsar Crab Nebula emissions from point of view of their modeling and applications for asteroid detection and imaging by applying inverse synthetic aperture radar (ISAR) principles. A huge value of the plasma’s e ﬀective temperature is a reason for pulsar emission coherency, a property of great practical meaning for a space objects navigation, localization and imaging. 
 A limitation of the method of inverse probability based on the application of Bayes' rule is  the difficulty of specifying the a priori probabilities. In most cases of practical interest, one is  ignorant of the a priori probabilities. For example, it would be necessary to specify the a priori  probability of finding a target at any particular range at any particular time. 
 SIDE THE REALMS OF KNOWN PHYSICS  AND THESE SEEM TO HAVE BEEN SEIZED ON BY SOME SECTIONS OF THE MEDIA ! CLAIM WAS MADE THAT A PARTICULAR '02 AND ITS OPERATOR COULD DETECT TARGETS THE SIZE OF GOLF BALLS AT A DEPTH OF EIGHT METERS #LEARLY  THE WAVELENGTHS CAPABLE OF PROPAGATING TO EIGHT METERS IN SOIL WOULD BE SO MUCH LARGER THAN A GOLF BALLnSIZED TARGET THAT THE RADAR CROSS 
 taken of the large forward-scatter signal are  limited. The scattering ang)e fJ must be exactly, or reasonably close to, 180° in order to obtain  forward scatter. Therefore the target must lie along the line joining the transmitter and receiver. 
 ARRAY LEVEL 3UB 
 Moore, and B. D. Warner, “Radar return measured at near-vertical inci - dence,” IEEE Trans. 
 Thus its range  variation should be identical to the clutter-power range variation. It has been suggested that  STC for a civil-marine radar have a gain proportional to R- out to a range of 8h, hw/31, after  which it is proportional to R-', where R = range, h, = radar antenna height, hw = wave  height from peak to trough, and A = radar ~avelength.~~ STC may be implemented in the IF  of the receiver, but it can also be incorporated at RF by inserting variable-attenuation micro-  wave diodes ahead of the receiver. A particular STC characteristic can be limited by changes in  clutter due to changes in ambient conditions (such as wind speed and direction, or by anoma-  lous propagation), and by the nonuniformity of clutter with azimuth. 
 SENTATION OF VOLTAGE IN OFFSET BINARY IS GIVEN BY   %   K;B. 
 III. Figure 7.6 shows the equivalent results with the radar at 1000 ft for ASV Mk. VI and ASV Mk. 
 SORT PROCESSOR THAT DEINTERLEAVES THE SEQUENCES BELONGING TO DIFFERENT EMITTERS AND IDENTIFIES 0ULSE 2EPETITION )NTERVAL 02)  VALUES AND MODULATION LAWS RANDOM JITTER  STAGGER  SWITCHING  &URTHER COMPARISON AGAINST AN EMITTER DATA 
  STEERING COMPUTATION  PERMITTING ALL SUBARRAYS TO RECEIVE IDENTICAL STEERING COM 
 Sun-synchronous spacecraft   that host optical instruments (such as Japan’s ALOS) choose the phase of the sun angle  to favor illumination of the surface, which usually leads to a midday orbit from which  most of the Earth’s surface is viewed at about the same local time, near midday. Such  orbits imply that the spacecraft must pass through the Earth’s shadow about half the  time, which has consequences on the design of the thermal and power subsystems in  particular. In contrast, spacecraft that carry only radars, such as RADARSAT, tend  toward favorable illumination of the spacecraft. 
 Tile Radio arid Elrctrottic Et~yitieer.  vol. 41. 
 Theabilityoftheoperator todetectradarsignalsinthepresence ofnoiseorclutter cannotbedetermined withasgreatareliability ascantheperformance oftheelectronic threshold detector described inChap.2.Humanbehavior iscertainly lesspredictable than thatofanelectronic device.However, itappears thatanoperator's performance canbeas goodasthatpredicted fortheidealelectronic threshold detectoriftheoperator iswelltrained, motivated, alert,notfatigued, andthedisplayisproperly designed. Furthermore, theoperator isprobably betterabletorecognize andinterpret patterns relatinggroupsofassociated echoes thancanautomatic devices.47 Ithasbeenshownexperimentally thatwhenanoperator viewsadisplayinwhichthe pulsesreceived fromsuccessive sweepsaredisplayed side-by-side without lossofmemory (fadingoftherecorded signalswithtime),theintegration improvement achieved byanopera­ torisequivalent towhatwouldbeexpected fromclassical detection theory.48,49 Thisis illustrated bythedataofFig.10.6,whichplotstheexperimentally observed signal-ta-noise rationecessary toachieveaprobability ofdetection of0.50asafunction ofthenumberof pulsesavailable onthedisplay. CurveAappliestoachemical recorder whichmakesa permanent record,andcurveBappliestoanintensity modulated B-scopeoflongpersistence. 
 !0 )NT !NTENNA 0ROPAG 3YMP 2EC  3EPTEMBER   2 # *OHNSON AND ( *ASIK   !NTENNA %NGINEERING (ANDBOOK   ND %D  .EW 9ORK -C'RAW 
 The resulting piecewise  continuous second-order doppler spectrum is usually some 20–30 dB weaker than the  first-order Bragg peaks but, being spread in doppler, has the potential to mask ship  echoes over much more of doppler space. Figure 20.10 is an example of the numerical  evaluation of Eq. 20.6 for a specific ocean wave spectrum. 
 ch20.indd   2 12/20/07   1:15:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 
 TARGET 
 ENCE OF ADAPTIVE NULLING v PRESENTED AT )%% #OLLOQUIUM ON !DVANCES IN !DAPTIVE "EAMFORMING  2OMSEY  5+  *UNE     & # ,IN AND & & +RETSCHMER  h!NGLE MEASUREMENT IN THE PRESENCE OF MAINBEAM INTERFERENCE v  0ROC OF )%%%  )NT 2ADAR #ONF  !RLINGTON 6!   53!  -AY n    PP n  5 .ICKEL  h-ONOPULSE ESTIMATION WITH ADAPTIVE ARRAYSv  )%% 0ROC  VOL   PT &  NO     PP n  /CTOBER   - 6ALERI  3 "ARBAROSSA  ! &ARINA  AND , 4IMMONERI  h-ONOPULSE ESTIMATION OF TARGET $O!  IN EXTERNAL FIELDS WITH ADAPTIVE ARRAYS v  )%%% 3YMP OF 0HASED 
 6 to 13.7.     I_11 linear array, 13.11 to 13.13 low sidelobes, 13.28 to 13.33 meteorological, 19.35 to 19.37 monitoring of, 13.4 to 13.5 monopulse tracking, 9.12 to 9.13, 13.4 multifunction, 13.1 mutual coupling, 13.20 to 13.22 optical feed, 13.46 parallel feed, 13.48 to 13.49 periodic errors in, 13.35 to 13.38 phase-only control, 13. 58 phase quantization, 13.34 phase shifters, 13.51 to 13.53 planar array, 13.15 to 13.19 radiation pattern nulling, 13.57 to 13.60 scanning, 13.7 to 13.9 series feed, 13.47 to 13.48 simultaneous receive beams, 13.54 to 13.56 small arrays, 13.27 solid-state modules for, 13.53 to 13.54 solid-state transmitter for, 11.24 to 11.31 subarrays, 13.43 to 13.44, 13.49 to 13.50 surface waves and mutual  coupling, 13.24 to 13.45 Taylor illumination, 13.29 thinned arrays, 13. 
 For small vessels the mast height will be of most importance.35 For surface targets where the maximum RCS is with vertical polarization, the 12 dB sky-wave RCS enhancement mentioned for the sea echo will occur. 24.7 NOISEANDINTERFERENCE In the HF band, receiving systems can be designed such that external noise is dominant. The major source of noise at the lower frequencies is lightning dis- charges ionospherically propagated from all over the world (sjerics). 
 Active radar measurements are made out to a few miles. The instant use terrain data - base extends out to perhaps ten miles. The terrain database cannot be completely current  and may contain certain systematic errors. 
 These dif ﬁculties would be eased to some extent by the development of the common TR unit, which was introduced during 1943. 2.2.2 ASV Mk. II equipment Much of the information presented here on ASV Mk. 
 MINAL AIRPORT SURVEILLANCE RADAR TRANSMITS A  
 The  prime difference between optical and microwave refraction is that water vapor has a negligible  effect on the former; consequently the second term of Eq. (12.9) may be neglected at optical  frequencies. Since the barometric pressure p and the water-vapor content e decrease rapidly  with height, while the temperature T decreases slowly with height, the index of refraction  normally decreases with increasing altitude. 
 63. R. Fante, R. 
 27-33.  March, 1963.  64. 
 Bistatic radar  lay dormant for about fifteen years until it was" reinvented" in the early 1950s and received  new interest.60  Separating the transmitter and receiver in the bistatic radar results in considerably differ­ ent radar characteristics than those obtained with the monostatic radar. The physical  configuration of a bistatic radar is closer to that of a point-to-point microwave communica­ tions system than to the usual scanning monostatic radar. In fact, histatic-radar detection of  aircraft with poinHo-point communications systems has often been reported in the literature. 
 ITY FROM VOLUMETRIC RADAR DATA TO CORRECT PRECIPITATION ESTIMATES v  * !PPL -ETEOROL   VOL     PP n  . £°{È  2!$!2 (!.$"//+    & & -ARZANO  % 0ICCIOTTI   AND ' 6ULPIANI  h2AIN FIELD  AND REFLECTIVITY VERTICAL PROFILE RECONSTRUCTION  FROM # 
 Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 4.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 filter bank. The advantage of pulse compression after the filter bank is that the effects of  doppler on pulse compression can be largely removed by tailoring the pulse compres - sion to the doppler offset of each doppler filter. 
 BaughlZ1 describes a "non-time-critical"  row/column beam-steering computer that represents a minimum equipment approach that  takes frorn 10 to 20 rns to generate the phase-shifter commands. He also describes a "time-  critical " design, which requires sonie form of adding device per element, that reduces the time  to 50 to 100 ~ts. The better the hardware the less can be the computation time. 
 Real signals have spectral components in conjugate pairs because by using com - plex amplitude expressed in polar form as  A = r ejq, A e j2p  ft + A* e−j2p  ft  = 2 Re{ Ae j2p  ft} = 2 Re{ r e jq e j2p  ft} = 2r Re{e j(2p  ft+q  )} = 2r cos(2p  ft+q ) The imaginary parts of the conjugate spectral components have canceled to reveal  that those components together indeed represent a real signal, a sinusoid with ampli - tude and phase specified by the magnitude and angle of the complex amplitude. The  latter relationship is so much a part of the engineering culture that the terms amplitude   and phase  are commonly, if imprecisely, used to refer to the magnitude and angle of a  complex signal at an instant in time. The following figures illustrate the origin of the Nyquist rate. 
 Thepurpose ofunequal elementspacing inahighlythinnedarrayistoeliminate the gratinglobesthatwouldappearifequalelementspacings oflargevaluewereused.Grating lobesarenotnecessarily undesirable, sincetheenergycontained inthegratinglobescanbe usedtodetecttargets.However, ifthisenergyisdistributed inthesidelobes byemploying unequalspacings, itiswasted.Thedisadvantage withdetecting targetsinthegratinglobesis thattheanglemeasurement canbeambiguous. Therearemethods, however, forresolving theseambiguities.l-l-O Insteadofthinning elements, thenumberofphaseshifterscanbethinned.I-l-1Thatis. someofthephaseshiftersinthearraycanbeusedtoadjustthephase of morethanone element, sothatthenumberofphaseshiftersislessthanthenumberofelements. 
 11.6 SOLID-STATE SYSTEM EXAMPLES PAVE PAWS (UHF Early Warning Radar).  The PA VE PAWS (AN/FPS-115)  system is a UHF solid-state active aperture phased array radar that was built for the  Electronic Systems Division of the U.S. Air Force by the Equipment Division of the  Raytheon Company during the late 1970s.33 The radar is a long-range system with a  primary mission to detect and track sea-launched ballistic missiles. 
 CASE SCENARIO WITH THE MAIN 
 TION OF THE RECEIVER )T IS DEFINED AS  SSC" C!   WHERE S" IS THE SCATTERING COEFFICIENT   OR THE CLUTTER CROSS SECTION PER UNIT AREA OF THE ILLUMINATED SURFACE 4HE CLUTTER CELL AREA  !C HAS BEEN DEVELOPED FOR BEAM 
 WATT AVERAGE POWER REQUIREMENT COULD BE PROVIDED BY ONLY  TO  OF THE  
 CM WAVELENGTH ARE COMBINED AT A  
 These maxima all have the same value and are equal to N. The maximum at sin O = 0  defines the main heam. The other maxima are called grating lobes. 
 ENA  A COMPLETE THEORY OF SEA CLUTTER SHOULD IDEALLY PROVIDE ACCURATE  A PRIORI PREDIC 
 The aspect entropy can still discriminate these two kinds of shapes by using the real data and the result is shown in Section 4. T able 1. The aspect entropy of canonical shapes. 
 22–28, May 2005. 22. “Raytheon’s APG-79 AESA radar for the F/A-18 Super Hornet sets a new standard as it delivers  multiple JDAMs simultaneously on target,” MarketWatch , December 5, 2005. 
 24.38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 Detection in a clear environment is a feature of early-warning radars,§ which look  primarily for high-altitude targets at long ranges beyond the surface horizon, where the  effects of clutter can be ignored. Under these conditions, a simplified analysis states  that radar performance is relatively insensitive to transmitter frequency and waveform  shape; in practice, the lower microwave frequencies are preferred because it is easier  to obtain large antenna and high average power at lower frequencies, and rain clutter  is not important. The maximum detection range on a target with a certain RCS ( s) in  free space, for a surveillance radar that must uniformly search a specified volume in  a given time period, depends on the product of the average transmitter power ( )P and  the effective antenna aperture ( Ar). 
 FortMsparticular case theprobability that themagnetron~vill start isincreased if(1)themagnetron hasashort starting time and hasa large voltage interval Vc-V, and (Z)thepulser delivers aslowlyincreas- ingvoltage between VSand VC. The internal impedance ofthe pulser, which determines the distance that Vomust beabove VC,also plays an important role inmode stability, but the optimum impedance depends onthe characteristics ofthe magnetron and thus cannot bestated in general. Particular combina~ions ofmagnetron and pulser frequently present situations much more complex than those shown inFig. 
 Beacons have been made inwhich the limit tothe rate ofreply was setbythe amount of interrogation necessary tooverheat thebeacon until itstarted afire, but this informal system has drawbacks. Itisusually desirable toincor- porate anarrangement forlimiting the average rate ofreply toasafe value. There aretwo principal ways ofdoing this. 
 Remote Sens. 2004 ,42, 2412–2425. [ CrossRef ] 21. 
 BASED (&372 WHEN THE  TRANSMITTER WAS CARRIED BY A SMALL BOAT TRAVELING OUT TO A RANGE OF ^ KM 4O AVOID  PERIPHERAL ISSUES CONCERNING ANTENNAS  THE '2 7!6% CURVES HAVE B EEN ARBITRARILY NOR 
 The plot of tlie electric field ititensity I E(0, 4)I is called thefie1d-intetrsity pattert~ of the  antenna. The plot of the square of tlie field intensity I E(0, 4) /* is the power radiatiotl patterti  P(O. c$), defined in the previous section. 
 K. Hughes24) ch07.indd   15 12/20/07   11:04:11 AMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 typical designs, 19.14 to 19.18 whitening filter, 19.24 wind profiler, 19.39 to 19.40 Method of moments, 14.1, 14.18 to 14.19 MFAR. See Multifunctional Fighter Aircraft Radar Microbursts, 19.29 to 19.31 Microwaves, 1.1, 1.14 Microwave monolithic integrated circuits (MMIC) characteristics of, 11.24 to 11.29 power amplifiers, 11.26 low-noise amplifiers, 11.26 phase shifters, 11.27 to 11.29 transmit/receive switching, 11.27 Microwave power module (MPM), 10.13 Military radar, 1.20 Millimeter waves, 1.14, 1.17 to 1.18 Mirror-scanned antenna, 9.25 Missile guidance performance assessment, 5.42 Missile-range instrumentation radar, 9.2 Mixer, image-reject, 6.13 Mixers, performance parameters, 6.14 Mixers, spurious response of, 6.11 to 6.13 MMIC. See Microwave monolithic integrated circuits. 
 The potential advantages claimed for solid-state sources in radar may  be summarized as ( l) long, failure-free life, (2) low transmitter voltage, which eliminates the  risk of X-rays and electric shock. (3) amplitude control of the transmitted waveform by selec­ tively switching modules or individual devices 011 or off, (4) wide bandwidth, (5) low projected  volume-production costs. and (6) air cooling. 
 ,Ê 
 Radar relay ismentioned here toemphasize itsusefulness asone element inthecreation ofanorganization fortheuseofradar data. An example ofanoperational system inwhich this technique isimportant isgiven inSec. 7“8.. 
   A    
 TO 
 Zhao, Q.; Lin, H.; Jiang, L.M.; Chen, F.L.; Cheng, S.L. A study of ground deformation in the guangzhou urban area with persistent scatterer interferometry. Sensors 2009 ,9, 503–518. 
 TO 
 TRONIC AXIS THAT CAUSES VARIATIONS IN PHASE AND TEMPERATURE VARIATION ACROSS THE ARRAY  SURFACE THAT CAUSES DISTORTION OF THE LENS 3IGNIFICANT VARIATION OF HEAT DISTRIBUTION ACROSS THE ARRAY FACE CAN RESULT FROM HIGH POWER TRANSMITTED THROUGH THE PHASE SHIFTING ELEMENTS AS WELL AS THE ELECTRONIC PHASE CONTROL #ONSEQUENTLY  WHERE HIGH PRECISION TRACKING IS REQUIRED  SPECIAL COOLING TECHNIQUES MAY BE NECESSARY TO MAINTAIN CONSTANT TEMPERATURE ACROSS THE APERTURE #ORPORATE &EED -ONOPULSE %LECTRONIC 3CAN 0HASED !RRAY  4HE CORPORATE FEED  ARRAY IS FED BY DIVIDING AND SUBDIVIDING THE TRANSMIT SIGNAL THROUGH TRANSMISSION LINES  TYPICALLY TO SUBARRAYS OF MULTIPLE ARRAY RADIATING ELEMENTS 4HIS TECHNIQUE  ALTHOUGH  TYPICALLY RESULTING IN HEAVIER AND HIGHER COST IMPLEMENTATION  OFFERS THE ADVANTAGE OF FLEXIBILITY OF CONTROL OF THE SIGNAL PATHS THROUGH THE ARRAY STRUCTURE  AS DESCRIBED IN #HAPTER  !NOTHER ADVANTAGE IS THE CAPABILITY TO TRANSMIT VERY HIGH PEAK POWER WITHOUT THE LIMITATIONS OF FULL PEAK POWER PROPAGATING THROUGH A SINGLE TRANSMISSION LINE 4HIS IS ACCOMPLISHED IN THE CORPORATE FEED ARRAY BY PLACING HIGH POWER AMPLIFIERS WHERE THE POWER DIVIDES TO THE SUBARRAYS  ALLOWING THE SUM OF THE HIGH PEAK POWER AMPLIFIER OUTPUTS TO ADD IN SPACE TO MEET REQUIREMENTS FOR LONG 
 C. R.: Laser Radar Systems, Some Examples. Proc. 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.48  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9  5. P. 
 If the antenna is active, then the transmitter (as well as the front  end of the receiver) is distributed over the array. In this case, several hundred T/R ele - ments, of a few watts peak power each, add up to many hundreds of peak radiated power.  Phase control of the elements is a critical parameter, usually requiring adaptive tempera - ture compensation to assure coherency of the radiated wavefront. 
 3/,!3 #LASS ! n n .ON 
 COUNTERMEASURES AGAINST CHAFF v  0ROC )NT #ONF  2ADAR  0ARIS  &RANCE  -AY   PP n   - ) 3KOLNIK  )NTRODUCTION TO 2ADAR 3YSTEMS  RD %D  .EW 9ORK -C'RAW 
 Amethod foraccomplishing this is illustrated inFig. 17.5. The basic pulse isinitiated byanexternal trigger and coded bythecircuit ofFig. 
 Pulse doppler radars are generally divided into two broad PRF categories: medium and high PRF.11 In a medium-PRF radar12"14 the target and clutter ranges and velocities of interest are usually ambiguous, while in a high- PRF radar 15 the range is ambiguous but the velocity is unambiguous (or has at most a single velocity ambiguity as discussed later). A low-PRF radar, commonly called a moving-target indicator (MTI),16 is one in which the ranges of interest are unambiguous while the velocities are usually ambiguous. MTI radars are generally not categorized as pulse doppler radars, al- though the principles of operation are similar. 
 The coherent gain of a doppler filter is equal to the increase in signal-to-thermal-noise ratio between the input and the output of the filter due to the coherent summation of individual target returns. PROBABILITY OF EXCEEDINGREFLECTIVITY cr° . TABLE 15.2 Typical Values of Clutter Reflectivity* *From Barton.8Clutter parameters for typical conditions x 0.032c 0.056 0.1L 0.23 Band X, m ConditionsReflectivity, X, m •n, fa)"1 Clutter -20 -22 -25 -29 a°dB = o 0.00032 a ~ x (worst 10 percent)Land (excluding point clutter) 104 104 104 IO4 am2 = a = 104 m2 Point clutter -42.5 -44.5 -47.5 -51.5 a° dB = Sea state 4 (6-ft waves, rough); E = 1°a0 dB = -64 + 6KB + (sin E)dB - X dBSea (Beaufort scale KB, angle E) io-9 1.7 xio-93 xio-97 xio-9TI (m)-1 = -n = 3 x io"8x Chaff (for fixed weight per unit volume) 5 xio-75 x 10~85 xio-92 xio-10TI (m)-1 = r = 4 mm/h TI = 6 x 10"1V-6X"4 (matched polarization)Rain (for rate r, mm/h) . 
 While many orders of  magnitude attenuation are possible with these masking and shielding techniques, addi - tional reduction is nearly always necessary. Howland reported a two-stage, spatial noise  canceller with an adaptive M-stage lattice predictor ( M = 50) as the first stage and an  adaptive tapped delay line as the second stage, which achieved ~75 dB cancellation  of the narrow-band stationary direct path signal.113,114 This cancellation combined with  masking achieved >90 dB attenuation, which satisfies the Cdp requirement in the above  example. Howland also observed that receiver dynamic range ultimately limits the avail - able cancellation, which, in turn, is set by the receiver’s analog-to-digital converter. 
 If the phases as well as the magnitudes of the  echoes are obtained, then such a radar is fully polarimetric . We may designate the choice  of polarizations as follows: HV is “transmit H, receive V ,” and so forth. Fully polarimetric SARs have been demonstrated (Sullivan et al.34 and Held et al.35). 
 AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 for 10 pulses integrated and 1.0 dB for 100 pulses integrated.28 An implementation  of the log CFAR29 is shown in Figure 7.19. In many systems, the antilog shown in  Figure 7.19 is not taken. To maintain the same CFAR loss as for linear video, the  number of reference cells Mlog for the log CFAR should equal  Mlog = 1.65 Mlin − 0.65 (7.16) where Mlin is the number of reference cells for linear video. 
 Standing waves are produced along  the line, causing an impedance mismatch and a degradation of the transmitter performance.  The mismatch can be corrected by an impedance-matching device, but this remedy is effective  only over a relatively narrow frequency band. Another technique for reducing the effect of the  reflected radiation intercepted by the feed is to raise a portion of the reflecting surface at the . 
 Ulaby developed a different, more complex model from the Kansas vegetation  data.117 This model fits curves rather than straight lines to the measured data. For most  purposes, the straight-line model is adequate, and it is much easier to use. A straight-line model for snow-covered grassland similar to that for vegetation  depends on a more limited data set.118,119 The data was for only one season in Colorado  when the snow was only about 50 cm deep. 
 For small look angles (a and B in Fig. 19.2), the main-lobe clutter (MLC) occurs at a fre- quency corresponding to a velocity of ap- proximately 2VM. Sidelobe clutter ex- tends all the way from 2VM to zero- doppler velocity (feedthrough) as the angle between the missile velocity vector and the reflecting clutter patch varies from 0° (head on) to 180° (backlobe clut- ter). 
 (The six pulses per CPI may be driven by system considerations, such as  time-on-target.) Because the filter will use six pulses, only five zeros are available for  the filter design; the number of zeros available is the number of pulses minus one. The  filter design process consists of placing the zeros to obtain a filter bank response that  conforms to the specified constraints. The example that follows was produced with an  interactive computer program with which the zeros could be moved until the desired  response was obtained. 
 The analysis starting with Eqs. (21.15) and (21.16) contains the assumption that a matched filter is applied to the radar returns from each point. This can in fact be done. 
 HANDLING CAPABILITIES OF THE ANTENNA ELEMENTS ARE ALSO A CONSIDERATION ! LOWER BOUND ON THE TRANSMIT ARRAY APERTURE IS SET BY THE NEED TO ACHIEVE ADEQUATE  DIRECTIVITY AND HENCE POWER DENSITY ON THE TARGET THE SENSITIVITY REQUIRED DEPENDS ON THE SIZE OF THE TARGETS OF INTEREST 4HE UPPER BOUND IS OFTEN SET BY THE REVISIT REQUIREMENTIN GENERAL  THE RADAR WILL STEP OVER A WIDE ARC  BUT IT MUST SAMPLE EACH REGION FREQUENTLY TO MAINTAIN TRACKS ON MANEUVERING TARGETS  SO THE TRANSMIT BEAMWIDTH SHOULD NOT BE TOO NARROW 4HE NEED TO KEEP 6372 TO MODEST LEVELS IS USUALLY ADDRESSED BY HAVING  TO  ARRAYS ADDRESSING SUBBANDS OF ABOUT ONE OCTAVE OF FREQUENCY EACH 3OME OF THESE CONSIDERATIONS ARE INFLUENCED BY THE ADVANTAGES THAT ATTACH TO EMPLOY 
 In the following sections different concepts of the CFAR processing  will be shown. An efficient CFAR circuit has to fulfill the following requirements:   Efficient implementation regarding r equired processing power and production costs,   Low CFAR- loss,  Accurate fitting of the CFAR threshold to the clutter scenario,   The CFAR threshold must pass point targets and extended targets,   Closely spaced targets must not mask each other,   The CFAR threshold must follow steep rises (or falls) in background clutter  ampl itude with as little lead (or lag) as possible     12.1.2  The CAGO -CFAR    . Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  114     L 321CUTL 321samples of the digital signalSUT-TVcomparator target identification. 
 Also, since the pulse power ofthe beacon transmitter can bemade asgreat as desired, there isnolimit tothe strength ofthe reply. The range is limited only bythepower oftheradar transmitter and the sensitivity of thebeacon receiver, which determine whether the beacon transmitter is triggered ornot. Figure 82a shows the radar echoes and Fig. 
 Onboard data storage capac - ity is 240 Gbits; downlink maximum data rate is 640 Mbits/s (X band, dual circularly  polarized). The RISAT orbit is sun-synchronous, dawn-dusk, at ∼609 km altitude, and  13-day revisit period. MAPSAR . 
 IIIC 3-15 3.5 Improvements to ASV Mk. III 3-16 3.5.1 ASV Mk. IIIB 3-16 3.5.2 Sea return discriminator 3-17 3.6 Detection performance of ASV Mk. 
 This centre electrode is connected  to an additional valve circuit providing low-power pulses  to close the circuit at predetermined intervals to provide  the PRF.  . IX. 
 W AY DIRECT SIGNAL FROM  RADAR TO TARGET AND THE TWO 
 IEEE T rans. Pattern Anal. Mach. 
 (21.23) var- ies slowly during each of these transmissions. This is equivalent to a statement that the electrical path length between a target and the radar changes by a small amount during each transmission. If this assumption is valid, the exponential term in Eq. 
 W. Helstrom, Statistical Theory of Signal Detection , 2nd Ed., Pergamon Press, 1968. 74. 
 Parzcn. E.: " Modern Probability Theory and Its Applications," John Wiley & Sons, Inc., New York,  1960.  9. 
 Being a transportable equipment, the antenna is  self-erecting and is stowed inside the shelter through a roof hatch. The radar system provides  coverage to 60 nmi and 40,000 feet with a 15 rpm rotation rate.  f•  Loss in gain. 
 ATMOSPHERIC FLIGHT  THE OBJECT IS FALLING WITH THE KNOWN ACCELERATION OF GRAVITY $URING ENDO 
 The elevation beamwidth is made broad enough (typically 20°) so that the  surface of the sea remains illuminated during the roll of the ship. A correction can be applied  to the indicator (data stabilization) to account for the error.  The two-axis mount of Fig. 
 In addition, the radar designer now has the option to compensate  for signal path fluctuations in both spatial and temporal domains, within limits, by  employing processing schemes that diagnose the nature of the signal corruption on a  first pass and then reprocess with algorithms that compensate for the observed corrupt - ing mechanisms.96,97 The signal processing stage may also be tasked with extracting  environmental information from the radar echoes, as mentioned in Section 20.8. This  includes remote sensing of ocean winds and sea state, land-sea mapping for coast - line recognition to assist with coordinate registration, measurements of the ionosphere  for assimilation into ionospheric models, extraction of echoes from remote beacons  deployed to assist with coordinate registration and calibration, and many other byprod - ucts of the basic detection mission. FIGURE 20.22  (a) Temporal fading and ( b) distribution properties of the target, clutter peaks, and noise  features in the doppler spectrum of Figure 20.21, computed from an extended data sequence ch20.indd   51 12/20/07   1:16:58 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 2017JJ3322, 2019JJ50639), the Key Project of Education Department of Hunan Province (No. 18A148, 16B004), and the Key Laboratory of Special Environment Road Engineering of Hunan Province (No. kfj130405). 
 16.4] ALTERNATIVE METHODS FOR OBTAINING COHERENCE 635 initially. The two lines are mounted close together inathermally insulated box sothat thetemperature changes equally forboth. 16.4. 
 If this assumption were not true, the filter which maximizes  the output signal-to-noise ratio would not be the same as the matched filter of Eq. (10.15). It  has been shown " I' that if the input power spectrum of the interfering noise is given by  [N,(.f)J2, the frequency-response function of the filter which maximizes the output signal-to-  noise ratio is  When the noise is nonwhite, the filter which maximizes the output signal-to-noise ratio is  called the NWN (nonwhite noise) matched filter. 
 IEEE 1981 ,69, 1380–1419. [CrossRef ] 22. Gupta, I.J.; Beals, M.J.; Moghaddar, A. 
 21, no. 10,  pp. 3–11, October 2006. 
 BAND METEOROLOGICAL  RADAR APPLICATION  4HE PANELIZED ALUMINUM REFLECTOR IS MECHANICALLY SCANNED VIA USE  OF A GIMBAL NOT SHOWN  4HE FEED  A DUAL 
 NOISE RATIO OF THE MATCHED CASE )N THE CASE OF  .  CONTINUOUS RANGE GATES SPANNING THE DURATION OF THE )00  EACH OF WHICH ARE MATCHED TO THE TRANSMIT PULSE WIDTH  THE APPROXIMATE AVERAGE ECLIPSING AND STRADDLE LOSS IS    APPROXIMATEECLIPSINGANDRANGEGATESTRADD LLELOSS  . . 
 Software- defined SAR (SD -SAR) is especially  suited for these developments.  In this short article, I will outline the e nvisioned functionality,  structure and features of software- defined Radar sensors.  The vision is not new: Connect the  antenna output to an A/D converter and process the signals dig itally. 
 RECEIVER DISTANCE  OR  BASELINE  TO SOLVE THE TRANSMITTER 
 First, consider the calculation of the reflector surface currents. It is assumed that  the field from the feed that is incident on the reflector has a spherical wavefront  with amplitude tapering defined by the feed pattern. So, as a first step, the feed is  mathematically modeled to determine the incident field amplitude and phase at the  reflector surface. 
 ENTLY  THE MULTIPLE LOOKS OF JAMMER NOISE TEND TO SMOOTH OUT THE INTENSITY VARIATION FROM PIXEL TO PIXEL  JUST AS IN THE CASE OF THERMAL NOISE. 
 Aportionofthetransmitted signalisintercepted byareRecting object (target)andisreradiated inalldirections. I.tistheenergyreradiated inthebackdirection that isofprimeinterest totheradar.Thereceiving antenna collects thereturned energyand delivers ittoareceiver, whereitisprocessed todetectthepresence ofthetargetandtoextract itslocation andrelativevelocity. Thedistance tothetargetisdetermined bymeasuring the timetakenfortheradarsignaltotraveltothetargetandback.Thedirection, orangular position, ofthetargetmaybedetermined fromthedirection ofarrivalofthereflected wave­ front.Theusualmethodofmeasuring thedirection ofarrivaliswithnarrowantenna beams.If relative motion existsbetween targetandradar,theshiftinthecarrierfrequency ofthe reflected wave(doppler elTect)isameasure ofthetarget'srelative(radial)velocityandmaybe usedtodistinguish movingtargetsfromstationary objects.Inradarswhichcontinuously track themovement ofatarget,acontinuous indication oftherateofchangeoftargetposition is alsoavailable.. 
 There has been important application of  the grid-controlled tube for radars in the past at HF, VHF, and UHF. It is still of value for  applications in these frequency regions and should be considered as a candidate when  designing a radar to operate at the lower frequencies. The constant efficiency ampli - fier should be of interest because of its higher efficiency when shaped waveforms are  needed for control of the radiated spectrum. 
 Radar 97 , Edinburgh, October 14–16, 1997, Publication no.  449, London, UK: IEE, pp. 55–59. 
 The frequency ofthetransmitter maybe changed for each pulse, with acorresponding shift inthe frequency ofthe local oscillator ofthe receiver. For example, the transmitter frequency— that is,the, carrier frequency—might alternate between two values, ~1 and jz,separated byafrequency interval greater than the receiver pass band. Echoes originating from thefirst transmitted pulse, atfrequency j,,would not beamplified ifreceived during the interval following the second pulse, forduring this interval the receiver would beintune only forechoes offrequency j,,and soon. 
 Livingstone, L. D. Arsenault, and W. 
 Following the development of the high power magnetron, the ﬁrst centimetric ASV radar, based on H 2S Mk. II, was ASV Mk. III, which is described in chapter 3. 
 PERFOR 
 OF 
 W. W.  Shrader, “Radar technology applied to air traffic control,” IEEE Trans. 
 S. Zrnic and A. Ryzhkov, “Polarimetry for weather surveillance radars,” Bull. 
 V-I, pp. 317-323. 41. 
 17”9). This method, which would require theuseofmultiple subcarriers, and would thus involve excessive bandwidth, complex multiple modulation and filtering, orboth, hasnever been used. Two component voltages and one reference voltage can be provided atdifferent a-cfrequencies, but this arrangement isnotsuitable foruse with aservomechanism. 
 An exam pk is  the commonly used moving window detector which examines continuously the Ji!~iJ} ~mples  within each quantized range interval and announces the presence of a target if m out of n of  these samples cross a preset threshoid. (This and other automatic detectors are described in  Sec. 10.7 and in Ref. 
 It is possible, however, to utilize matched-  filter processirlg in the FM-CW radar in a manner similar to that employed with FM (chirp)  pulse compression radar as described in Sec. 11.5, and thus overcome the lower sensitivity and  rrii~ltiple-target prot>lems.3R.39 As the duty cycle of an FM pulse compression waveform in-  creases it becomes more like the FM-CW waveform of unity duty cycle. Hence, the processing  Figure 3. 
 Microphonism. Microphonism can cause the appearance of additional noise sidebands on the spillover and occasionally on the clutter signals. If the structures are sufficiently massive, the microphonism is greatest at the lower frequencies, where it can be counteracted by a feedthrough servo. 
 101 106, October, 1964  6. Kirk, J. C., Jr.: A Discussion of Digital Processing in Synthetic Apcrtt~re Radar, lEEE Truns.,  pp. 
   PP n  *ANUARY    $ % "ARRICK  h2EMOTE SENSING OF SEA STATE BY RADAR v #HAPTER  IN  2EMOTE 3ENSING OF THE  4ROPOSPHERE  6% $ERR ED   "OULDER  #/ ./!!%NVIRONMENTAL 2ESEARCH ,ABORATORIES     PP n   $ $ #ROMBIE  h$OPPLER SPECTRUM OF THE SEA ECHO AT  -CS v  .ATURE  VOL     PP n     * 7 -ARESCA  *R AND *2 "ARNUM  h4HEORETICAL LIMITATION OF THE SEA ON THE DETECTION OF LOW  DOPPLER TARGETS BY OVER 
 BEAM CLUTTER 4HUS  ALTHOUGH MEDIUM 02& PROVIDES ALL 
 The ditierence frequency between thecoher- entoscillator and thestandard ischosen as70kc/see. ILot. cit.. 
 TIME ANALYSIS FOR VIRTUAL RANGE AND AZIMUTH CORRECTION TO GREAT 
 Fuks, “Multiple scattering of HF radiowaves propagat - ing across the sea surface,” Waves in Random Media , vol. 8, pp. 283–302, April 1998. 
 However, Figure 9.2846,47 provides a practical means for approximating  multipath-error values in this region. The curves are calculated multipath errors  based on an assumed gaussian-shaped sum pattern and derivative of the sum pattern  ch09.indd   39 12/15/07   6:07:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The standard approach is strip mapping, in which the ambiguity-free  space is (nearly) filled with the allowable swath, resolution, and number of looks. Of  course, (azimuth) resolution can be increased within the allowed space at no loss of  swath width if the number of looks is decreased in proportion. SpotSAR.35,36 If (azimuth) resolution is the driving objective, then rAz may be  reduced as long as the integration time TAz is increased in proportion. 
 -t,  pt. l, pp. 242-247, 1956. 
 Crispin. J. W., R. 
 Metal inclusions have been considered  for use with dielectric layers to achieve frequency filtering, broad-frequency-band  performance, or reduced-thickness radomes. Thin layers of metal inclusions exhibit  the characteristics of lumped circuit elements shunted across a transmission line. For  example, a grid of parallel metal wires exhibits the properties of a shunt-inductive  susceptance. 
 Amplitude and phase linearity were con - strained to be better than 0.1% and 0.001 radian, respectively. The transmitted pulses  were linear FM, at 10% bandwidth in all three bands. Nominal free-space resolutions  were 300 m, 100 m, and 10 m. 
 BAND SINGLE 
 IEEE T rans. Geosci. Remote Sens. 
 T able 2. Traditional augmentation. Operation Parameter Rotate 90,180 Brightening 1.5 Color enhancement 1.5 Contrast 1.5 Sharpness 3.0 Flip Top bottom     (a) (b) (c)  Figure 11. 
 Craig and M. Hershberger, “FLAMR operator target/OAP recognition study,” Hughes Aircraft  Report No. P74-524, January 1975, Declassified 12/31/1987. 
 PuckLe, O. S.: Time Bases and Time Base Generators  (Chapman and Hall, 1946).  REYNER, J. 
 LATED RANGE WITH THE HIGHEST  - 
 BORNE RADAR IN FACT  AN OFTEN WEAK TARGET SIGNAL IN THE MAIN BEAM HAS TO COMPETE WITH JAMMER THAT PROPAGATES NOT ONLY VIA DIRECT 
 Insomeinstances, propeller modulation canbe ofadvantage. Itmightpermitthedetection ofpropeller-driven aircraftpassingonatangential trajectory, eventhoughthedoppler frequency shiftiszero.Therotating bladesofahelicopter andthecompressor stagesofajetenginecanalsoresultinamodulation oftheechoanda widening ofthespectrum thatcandegrade theperformance ofCWdoppler radar. Ifthetarget'srelativevelocity isnotconstant, afurtherwidening ofthereceived signal spectrum canoccur.IfQ,istheacceleration ofthetargetwithrespecttotheradar,thesignal willoccupyabandwidth (3.3) If,forexample, Q,istwicetheacceleration ofgravity,thereceiverbandwidth mustbeapproxi­ mately20Hzwhentheradar'swavelength is10em. 
 Terms such as quasi-bistatic, quasi- . monostatic, pseudo-mono static, tristatic, polystatic, real multistatic, multi- bistatic, and netted bistatic have also been used.17"20 They are usually special cases of the broad definitions given above. Passive receiving systems, or electronic support measure (ESM) systems, of- ten use two or more receiving sites. 
 Jt can be dispensed from  aerial rockets and fired ahead, behind, above, or below the target aircraft. Forward-shot chalT  can deceive the range and velocity tracking gates of tracking radars.  The effects of cha IT can be reduced by a properly designed MTI. 
 Some radar systems are designed to follow a target once it has been detected, and this tracking function requires a specially designed antenna different from a surveillance radar antenna. In some radar systems, . particularly airborne radars, the antenna is designed to perform both search and track functions. 
  RADAR  ARE COMBINED IN A WAVEGUIDE SWITCH FOR SELECTING POLARIZATION 4HE SWITCH SELECTS EITHER THE VERTICAL OR THE HORIZONTAL INPUT COMPONENT OR COMBINES  THEM WITH A   RELATIVE PHASE FOR CIRCULAR POLARIZATION 4HIS FEED DOES NOT PROVIDE  OPTIMUM SUM 
 3.13] SEA RETURN AND GROUND RETURN 95 incomparison with the wavelength, and \vhich have the same reflection coefficient K,reflect signals ofequal intensity and must bedistinguished from each other through large-scale irregularities such ashills, structures, and bodies of~vater. TOmake these large-scale irregularities most easy todetect, itisdesirable that theantenna pattern besmooth and properly shaped toproduce onthe radar picture aneven background against which irregularities will stand out, bycontrast, The shaping ofthe. 96 PROPERTIES OF RADAR TARGETS [SEC. 
 ................................ ..............  7  Direction determination  ................................ 
 2. The receive beamwidth must be narrow enough to provide the required lo- cation accuracy. 3. 
 The sawtooth generator shown inthe block diagram con- verts the circuit tothe more desirable “search and lock” type. The sawtooth “sweeps” the local-oscillator frequent yuntil the change in polarity ofthediscriminator output when “crossover” isreached results ATRswtch Antenna Attenuator _ ,.-.,,- -\r__-7 AFc mIxer IIFampl,fier andd,scr,. ml”ator B--z$!:--[i@FIG.1212.-Block diagram oftypical AFC; beacon AFC portion isshown asdotted line insignals ofproper polarity tooperate acircuit which stops thesawtooth. 
 ofappreci:~hle maguit udc arecombiuccl. Insome applications reqllh-iug afixed component offield, aperman{’nt mngnet isIIMT1 inIi?u (of3coil. Often coils are arranged orthogonally (I~ig. 
 C. Johnson and H. Jasik (eds.),  2nd ed., New York: McGraw-Hill Book Company, 1984. 
 2, pp. 73-85, October 1965. 14. 
 Thereissomeevidence toindicate thatcrossedlinearpolarization maygive betterrainrejection thanconventional circular polarization. I,og-FTC receiver. Areceiver withalogarithmic input-output characteristic followed bya high-pass filter(fast-time-constant, orFTC,circuit), willprovideaconstant false-alarm rate (CFAR)attheoutputwhentheinputclutterornoiseisdescribed bytheRayleigh probability densityfunction. 
 The klystron amplifier may be pulsed by turning on and off the beam  accelerating voltage, similar to plate moduiation of a triode or magnetron. The modulator in  this case must be capable of handling the full power of the beam. When the tube is modulated  by pulsing the RF input signal, the beam current must be turned on and off; otherwise beam  power will be dissipated to no useful purpose in the collector in the interval between RF  pulses, and the efficiency of the tube will be low. 
 RAYS WHERE TIME 
 V.: Range Resolution of Targets Using Automati~ Detectors, Naval Research Laboratory  Rcrc. 8178. Nov. 
 L. E. Brennan., J. 
 J. aufm Kampe: Physical Properties of Cumulus Clouds, J. MeteoroL, vol. 
 A Sunderland Mk. V showing one of the ASV scanner radomes [©IWM ATP 13694B].Airborne Maritime Surveillance Radar, Volume 1 4-25. attenuator controls required much concentration and practice to achieve an appropriate increase in attenuation as range decreased. 
 Orthogonal circular-polarization components canalsobeused todescribe thepolarization matrix.Bytransmitting twoorthogonal polarizations andmeasur­ ingtheamplitude andphaseofthereceived echoesoneachpolarization, aswellasthe cross-polarization component, ameansoftargetdiscrimination, orclassification, canbe provided. Someinformation aboutthetargetcanbeobtained fromtheamplitude only,and notthephase,ofthe·polarization components. Ithasalsobeensuggested thatthecross­ polarized component ofthebackscattered echofromsimpleaxiallysymmetric objects(suchas disks,cones,and corie-spheres) canprovideanestimateofatransverse dimension ofthebody andgiveanindication oftheseverityoftheedges,or··edginess.'''~7. 
 The false-alarm probabilities of practical radars are quite small. The reason for this is that  the false-alarm probability is the probability that a noise pulse will cross the threshold during  an interval of time approximately equal to the reciprocal of the bandwidth. For a 1-MHz  bandwidth, there are of the order of 106 noise pulses per second. 
 A. Bennett, “Analytic ray parameters for the quasi-cubic  segment model of the ionosphere,” Radio Science , vol. 32, pp. 
 GEOMETRY WITH ALMOST ALL WAVEFORM PARAMETERS SET BY LOCAL EARTH CONDITIONS   4HE MODERN RADAR OFTEN IS NET 
 ” The signals required toproduce the desired modulation are derived from thedevice illustrated inFig. 7.8. The desired map, intheform of opaque lines on atransparent background orvice versa, isplaced immediately infront ofanauxil- iary PPI ofthe highest precision obtainable. 
 Figure 6.1. Lucero installation [ 3]. Table 6.1. 
 The length of the square pulse during the flip-flop action can beeasily controlled by varying RIC1orthepotential applied toRI.This voltage ismade posi- tive toassure that glwill berising sharply when the cutoff point is reached; this helps maintain-a constant square-wave duration. Typical circuit constants areindicated inthe grid circuit ofV2. The condenser Czserves only toquicken the regenerative action and isnot essential except forthehighest speed operation. 
 POLARIZED SIGNALS AT VERTICAL ARE NEGLIGIBLE  SO EVEN AT LOW FREQUENCIES  THE  CROSS 
 SEC.16.2] BASIC PRINCIPLES OF MTI 629 heard inthe phones. The echo frequency isgiven bythe well-known doppler formula fl=gf. The beat frequency isthen Since the target velocity visvery small compared light c,this can bewritten aswith the velocity of Forvinmiles perhour and kincmthis becomes f,=E x“ See, forexample, Fig. 
 Anexample ofatraveling-wave tubedesigned forradarapplications istheS-bandVarian VA-125A. Itisabroadband, liquid-cooled TWTwhichusesacloverleafcoupled-cavity slow-wave structure.Itiscapableof3MWofpeakpowerovera300MHzbandwidth, witha 0.002dutycycle,a2-pspulsewidth,andagainof33dB.Thistubeissimilarinmanyrespects totheVA-87klystron amplifier.Itwasoriginally designed tobeusedinterchangeably withIhe VA-87klystron, exceptthattheVA-125TWThasabroader bandwidth andrequires alarger inputpowerbecauseofitslowergain. .~ Inaddition tobeingusedasthepowertubeforhigh-power radarsystems, thetravding­ wavetubehasalso been employed, atlowerpowerlevels,asthedriverforhigh-power lubes (suchasthecrossed-field amplifier), andinphasedarrayradarswhichusemanylubesto achievethedesiredhigh-power levels. 
 A. Ziegler, “MTI improvement factors for weighted DFTs,” IEEE Transactions  on Aerospace and Electronic Systems, vol. AES-16, pp. 
 10”23. The frequency ofthe single tuning cavity ischanged bydistorting thediaphragm. Since thetuning cavity istightly coupled toone oftheresonant cavities, and since allthe FtQ. 
 $ #'                  
 TO 
 315. Sensors 2019 ,19, 1529 Figure 3. Flow chart of the simulation method. 
 For instance, the mean proﬁles from the Crab pulsar consist of two frequency- dependent components, the main pulse (MP) and inter-pulse (IP). They appear at 70 and 215 degrees of the pulsar’s rotation phase, and can be identiﬁed from low radio frequencies to hard X-rays. The Main Pulses of the pulsar Crab emission are of particular interest for localization, navigation and imaging purposes. 
 A target is then declared in a range-azimuth  cell if the new value exceeds the average background level by a specified amount. Adaptive Thresholding . The basic assumption of the adaptive thresholding tech - nique is that the probability density of the noise is known except for a few unknown  parameters. 
 Thousands oftimes asmuch work hasgone into pulse radar asinto any other kind, and theoverwhehning majority ofthis work has been concerned with microwave pulse radar. The superiority of microwaves foralmost allradar purposes isnow clear. The first eight chapters ofthis book areintended toprovide anintro- duction tothefield ofradar and ageneral approach tothe problems of system design. 
 Moffatt, D. L., and R. K. 
 -(Z -!23)3 RADAR SOUNDER TO PROBE THE -ARTIAN SURFACE DUR 
 4.4). The delay-line canceler acts as a filter to eliminate the d-c component of fixed targets  and to pass the a-c components of moving targets. The video portion oft he receiver is divided  into two channels. 
 SUREMENTS MADE AT  LOCATIONS THROUGHOUT THE WORLD 4HE MEASUREMENT AND DATA  ANALYSIS WERE PERFORMED TO EXCLUDE INDIVIDUAL COLLECTION SITE LOCAL THUNDERSTORM CON 
 104. Kay, A. F.: Electrical Design of Metal Space Frame Rado mes, IEEE Trans., vol. 
 TUDE AT A COST OF ABOUT  D" IN TRANSMITTER EFFICIENCY !MPLIFIER CHAIN RADAR SYSTEMS  WHETHER TUBE OR SOLID STATE  OFTEN USE SOME SHAPING  OF THE EDGES OF THE TRANSMITTED 2& PULSE TO REDUCE THE 2& SPECTRUM WIDTH 4HIS CAN BE DONE BY SIMPLY SLOWING THE RISE AND FALL TIMES OF THE EXCITER SIGNAL TO THE TRANSMITTER  AND THIS APPROACH GENERALLY HAS BEEN ADEQUATE TO SATISFY -ILITARY 3TANDARDS AND RELATED SYSTEM REQUIREMENTS 3PECTRAL .OISE IN $OPPLER 2ADARS  4HE DOPPLER FREQUENCY SHIFT IS WIDELY USED  TO DETECT MOVING TARGET ECHO SIGNALS IN THE PRESENCE OF LARGE CLUTTER ECHOES (OWEVER  IF THE RADAR TRANSMITTER GENERATES NOISE OR ITS PULSE WAVEFORM  HAS SIGNIFICANT SPEC 
 QUENCY &INALLY  SINCE THE PARTICLES ARE IN MOTION WITH RESPECT TO ONE ANOTHER  THERE IS ALSO A DOPPLER SPREAD  OFTEN REFERRED TO AS THE WIDTH OF THE DOPPLER SPECTRUM :RNIC DESCRIBES A STRAIGHTFORWARD TECHNIQUE OF SYNTHESIZING DIGITAL WEATHER RADAR SIGNALS FROM A PARAMETERIZED DOPPLER SPECTRUM CHARACTERIZING A SPECIFIC PULSE VOLUME   $OVIAK AND :RNIC AS WELL AS "RINGI AND #HANDRASEKAR GIVE DETAILED DERIVATIONS OF  THESE RELATIONSHIPS  WHEREAS +EELER AND 0ASSARELLI SUMMARIZE DISTRIBUTED TARGET DATA  CHARACTERISTICS AND RELATE THEM TO THE SAMPLED DATA SETS REPRESENTATIVE OF WEATHER RADAR AND OTHER ATMOSPHERIC SOUNDING SYSTEMS. £°Óä  2!$!2 (!.$"//+  3PECTRUM  -OMENT  %STIMATION  ! COMMON 'AUSSIAN MODEL OF THE MEAN  RECEIVED POWER SPECTRAL DENSITY OF A METEOROLOGICAL SIGNAL IS DEPICTED IN &IGURE   AND CAN BE INTERPRETED AS FOLLOWS 4HE RECEIVED POWER IS SIMPLY THE INTEGRAL UNDER THE  CURVE THE ZEROTH MOMENT  AND IS GIVEN BY   03 F D F3 V D VR  ¯¯       WHERE F AND V ARE RELATED BY F   K V 4HE MEAN VELOCITY  V  IS GIVEN BY THE FIRST MOMENT OF THE SPECTRUM   VV3 V DV 3VDV ¯ ¯       4HE  SPECTRUM VELOCITY  WIDTH  RV  IS GIVEN BY TAKING THE SQUARE ROOT OF THE SECOND  CENTRAL MOMENT   SVVV3 V D V 3VDV 
 From10mWto100kW,theoutputflat-leakage increases byaslittleas3to10dB.Below l-Winputpower,thediodealoneprovides thelimitingaction.Abovel-W,theTRtubeionizes toprotectthediodelimiterfromburnout. Morethanonediodemayheusedtoprovide greaterattenuation orlargerbandwidth. - Beforetheintroduction ofthesolid-state diodelimiter,alow-power gasTR-tube, known asaprotector TR,wasoftenusedasaddedprotection forthereceiver. 
 Thenoiseandspurious signalsgenerated byaCFAcanbequitelowwhenthetubeis lockedinandcontrolled byanRFdrivesignal.1?Measurements ofnoisemadewiththe voltages appliedbutwiththetubeinactive becauseofnoRFdrive-signal, indicate thenoiseto approach whatwouldbeexpected fromitsthermal level.Intrapulse noiseisgenerally much higher.Spurious signalscanalsoariseduringtheflatpartofthepulse.ThegreatertheRF drivethelesswillbethein-band noise.Thusthelowerthegainthelesswillbethenoise. Pedestals cana'ppearattheleadingandtrailingedgesofthepulse,somewhat likethe"rabbit ears"foundintraveling-wave tubes.Theycanbecausedbythefeedthrough oftheRF drive-pulse whenitiswiderthanthed-cmodulator pulse,ortheycanbeduetospurious oscillations, calledband-edge oscillations, thatoccurjustoutside thenormal tube­ bandwidth.16•17 Theinsertion lossofaCFAislowandmightbelessthan0.5dB.TheRFdrivewillthus appearattheoutputofthetubewithlittleattenuation. Inalow-gain amplifier theinputpower whichappearsattheoutputcanbeasizablefraction ofthetotal.Theconversion efficiency of aCFAisdefinedas Effi. 
 BREATHING TARGETS   DETECTION FUSION PRODUCES THE MOST ACCURATE TRACK SMALLEST 2/5   AFTER 7"ATH Ú )%%  . Ç°xä  2!$!2 (!.$"//+  )&& )NTEGRATION  4HE PROBLEM OF INTEGRATING RADAR AND MILITARY )&& DATA IS LESS  DIFFICULT THAN THAT OF INTEGRATING TWO RADARS 4HE QUESTION OF WHETHER DETECTIONS OR  TRACKS SHOULD BE INTEGRATED IS A FUNCTION OF THE APPLICATION )N A MILITARY SITUATION  BY INTEGRATING DETECTIONS ONE COULD INTERROGATE THE TARGET ONLY A FEW TIMES  IDENTIFY IT  AND THEN ASSOCIATE IT WITH A RADAR TRACK &ROM THEN ON  THERE WOULD BE LITTLE NEED FOR RE 
   2!$!2 $)')4!, 3)'.!, 02/#%33).'   Óx°Ó£ TRANSMITTED SIGNAL WILL HAVE ARBITRARY PHASE FROM PULSE TO PULSE  MAKING DOPPLER  PROCESSING DIFFICULT IF NOT IMPOSSIBLE 4HE #,%!2 CONTROL PROVIDES THE MEANS TO DO THIS )N SOME APPLICATIONS  LIKE FOR A TRANSMIT BEAMFORMER  THE STARTING PHASE IN EACH CHANNEL MAY NEED TO BE DIFFERENT IN ORDER TO STEER THE BEAM )N THIS CASE  WE COULD PROVIDE A MECHANISM TO SET THE PHASE TO THE DESIRED VALUE AT THE BEGINNING OF A PULSE INSTEAD OF SIMPLY CLEARING IT 4HE $$3 CAN ALSO BE USED TO GENERATE LINEAR AND NONLINEAR &- hCHIRPv WAVEFORMS  4HIS IS ACCOMPLISHED BY PROVIDING CIRCUITRY THAT CHANGES THE TUNING WORD FROM SAMPLE TO SAMPLE IN ORDER TO PROVIDE  THE DESIRED FREQUENCY OR PHASE  MODULATION &OR EXAM 
 Letting  P* = S(f) exp (j2nft 1) and Q = H(J)  and recalling that  f p• p dx = f Ip 12 dx (10.10)  (JO.I I) . DETECTION OF RADAR SIGNALS IN NOISE 373  we get, on applying the Schwartz inequality to the numerator of Eq. ( 10.10),  Cl" 00  r I H(f) 12 df r I su:i 12 df  • -CO • -00 RI < ----------- - N_o 100 IHU)l2 df  2 . 
 219-225, April 1962. 51. Kallmann, H. 
 The dynamic range of each com- ponent is computed by comparing the maximum signal and system noise levels at the output of each component. The assumption inherent in this method is that all filtering (bandwidth reduction and decoding) by this component is accomplished prior to any saturation. It is important to treat those stages of the receiver that provide significant filtering as separate elements; if multiple stages are lumped into a single filter, this assumption may be grossly in error. 
 Zulaica, “Digital image synthesizer: Are enemy sensors really  seeing what’s there?,” IEEE Aerospace and Electronic Systems Magazine , vol. 24, no. 2, pp. 
 TER MIGHT BE ONE MILLION WATTS ONE MEGAWATT  AND WITH THESE NUMBERS  THE AVERAGE POWER FROM THE TRANSMITTER IS ONE KILOWATT !N AVERAGE POWER OF ONE KILOWATT MIGHT BE LESS THAN THE POWER OF THE ELECTRIC LIGHTING USUALLY FOUND IN A hTYPICALv CLASSROOM 7E ASSUME THIS EXAMPLE RADAR MIGHT OPERATE IN THE MIDDLE OF THE MICROWAVE o FRE 
 TION OF MOST SURFACE COMBATANTS 2ECOGNITION AIDS USING PRESTORED SHIP PROFILES ALLOW IDENTIFICATION TO HULL NUMBER IN MANY CASES !N EXAMPLE OF A SINGLE )3!2 IMAGE OF A LANDING ASSAULT SHIP IS GIVEN IN &IGURE  4HE RADAR IN THIS CASE IS ILLUMINATING &)'52%  )NVERSE 3!2 NOTION &)'52%  3INGLE )3!2 SHIP IMAGE . 
 However, it offers the possibility of determining and/or of differentiating between structures.  As an example, vegetatio n (trees, plants, etc.) normally  reflects with vertical polarization substantially more strongly than with horizontal polarization, since  vegetation is usually aligned vertically. However, de -polarization on the propagation path represents  a problem (there fore the use of polarization diversity with communications satellites). 
 The E vector and the 11-m dimension are in the same plane; 0° (nose-on), 15°, 45°, and 90° (broadside) curves are given. The top dashed curve is for a resonant dipole at 90°. The little sketches at the first, second, and third resonances of the 11- by 1-m target show how the RCS behaves with an illumination aspect.I - METERS DIPOLE MONOPOLE (L = M4) MONOPOLE (L = ^/4 @ 4 MHz) HEMISPHERE (R = */2?r) HEMISPHERE (R = M2n @ 4 MHz)RADARCROSSSECTION - DBSMRADAR CROSS SECTION (dBSM) . 
 Forcing the Jammer to spread power over the entire band available to a radar is generally  not sufficient in itself. The jammer also must be forced to spread its available power over more  than one radar band. This can be accomplished with frequency diversity by using two or more  radars. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.656x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 146. 
 , Ê " 
 TRONS AND 474S   )N THE )/4  THE WIRE GRID OF A GRID 
 TION IS BRIEFLY REVIEWED BELOW ,OCKHEED -ARTIN #ORPORATION 0HASED !RRAY 2ADARS  #OURTESY OF ,OCKHEED  -ARTIN #ORPORATION  !.309 
 /\ bank or contiguous receivers. each tuned to a  different frequency. provides coverage or the elevation sector with the equivalent of parallel  receiving beams. 
 20. flcan. 1%. 
 961. 69. Ref. 
 r}   WHERE}NIS  THE NORMAL TO THE REFLECTOR SURFACE 4HE APPLICATION OF THE EQUIVALENCE  PRINCIPLE TO 0/ 
 Its efficiency is  40 percent and gain is 30 dB. A peak beam voltage of 145 kV is required. The VA-812C formed  the basis ror the design of the VA-842, a tube used in the Ballistic Missile Early Warning  System (BMEWS), with a demonstrated life in excess of 50,000 hours. 
 However, it is known that radar beam bending caused  by atmospheric refraction and the resulting anomalously propagated ground clutter  echo gives an indication of the vertical profiles of temperature and moisture in the  intervening lower atmosphere. Moreover, measuring the propagation speed of the  radar pulse between normally propagated clutter targets (those directly viewed by  the radar) gives an estimate of the refractive index of air along this propagation path.  By measuring the absolute phase of the radar signal received from stationary ground  clutter targets and comparing them with reference absolute phase measurements under  known refractive conditions, one can measure the near surface propagation speeds  of the radar pulse along these paths. 
 R. K. Raney et al., “RADARSAT,” Proc. 
 The normalized cross-correlation function is the mutual  coherence function  γ12 1 212 1 2 12 22( , )( , ) [|| ] [|| ]t tR t t E s E s=  (18.13) in parallel to that encountered in physical optics.50 Gamma is a quantitative mapping  of the coherence between the two observations. In general, scene coherence decreases  with shorter wavelength and longer time between observations. Mutual coherence is an essential ingredient for radar interferometry. 
 POLARIZED DOUBLY CURVED 643 RADAR ANTENNA #OURTESY OF %ASAT !NTENNAS ,TD . 
 639-652. May, 1976.  22. 
 OF 
 LEMS IN THE MIXING PROCESS 4HE SUPERHETERODYNE RECEIVER VARIES THE ,/ FREQUENCY TO FOLLOW ANY DESIRED TUNING VARIATION OF THE TRANSMITTER WITHOUT DISTURBING THE FILTERING AT )& 4HIS SIMPLIFIES THE FILTERING OPERATION AS THE SIGNALS OCCUPY A WIDER PERCENTAGE #HAPTER     4HIS CHAPTER INCORPORATES MATERIAL WRITTEN BY *OHN 7 4AYLOR  *R FOR THE FIRST AND SECOND EDITIONS AND UPDATED  BY -ICHAEL 9EOMANS FOR THIS EDITION. 
 Time and frequency weighting are nearly equivalent for linear FM and cause a 1 to 2 dB loss in SNR. Passive linear-FM generation and processing may be used as in Fig. 10. 
 Allthat isrequired istogetthis information into the aircraft, where itcan bedisplayed toand used bythe pilot. Itisproposed toadd tothe display ofaground radar achart that contains map, airways, and weather information ofinterest topilots, and tosend theresulting picture bytelevision totheaircraft, where itisdis- played tothe pilot. Televising ofthe display ispreferred tothe use of the radar-relay methods described inChap. 
 Accuracy should not be  confused with radar resolution.     The stated value of required  accuracy represents the  uncertainty of the reported value  with respect to the true  value  and indicates the interval in  which the true value lies with a  stated probability. The  recommended probability level is  95 per cent, which corresponds  to 2 standard deviations of the  mean for a normal (Gaussian)  distribution of the variable. 
 LIKE MEMBRANE THAT IS STRETCHED ACROSS THE SURFACE AND ATTACHED AT A FINITE NUMBER OF POINTS TO FORM THE REFLECTING SURFACE )N EITHER CASE  THERE ARE SURFACE DISTORTIONS BETWEEN THE PRECISELY CON 
 J., and G. O. Hall: A Comparison of Techniques for Achieving Fine Azi- muth Resolution, IRE Trans., vol. 
 Zhang, M. J. Sowa, and B. 
 Although many others arepossible, they have had little ornopractical application todate.. 164THEGATHERING ANDPRESENTATION OFRADAR DATA (SEC. 6.4 I.One-dimensional deflection-modulated displays. 
 The important resolution cell size factors, receiver antenna beam width and spectral bandwidth, are not explicitly contained in Eq. (24.1) 5. Propagation factors (Fp): Several propagation phenomena, including Faraday polarization rotation, multipath, and ionospheric focusing, may need in- clusion in the equation. 
 Arrays have been realized in practice which have peak sidelobes in the vicinity of the -45 dB level; however, these are generally mechanically scanned, and the low error budgets are achieved by using all-passive feed components. Future an- tenna development will yield -45 dB sidelobe antennas which do scan electronically.12 Two additional techniques to prevent jamming from entering through the ra- dar's sidelobes are the so-called sidelobe blanking (SLB) and sidelobe cancelers (SLC). An example of the practical effectiveness of the SLB and SLC devices is presented in the literature, where the plan position indicator (PPI) display is shown for a radar, subject to an ECM, equipped with and without the SLB and SLC systems.17 Other discrimination means are based on polarization. 
 ch22.indd   14 12/17/07   3:02:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 
 The effect of the differential earth gravity field has been shown by Hord17 to be negligible for tracking-phase dura- tions not exceeding 10 to 20 min. Furthermore, Wolverton16 has shown that when the rendezvous time tr is small compared with the product of the satellite orbital period J0 and (2Tr)"1, the orbital motion aspects of the rendezvous maneuver can be neglected. Type IISBR. 
 (21.7). It will be noted that for the unfocused case the transverse linear resolution is independent of the antenna aperture size, fineness of resolution is increased by the use of shorter wavelengths, resolution varies as the square root of X, and the resolution deteriorates as the square root of range. A plot of Eq. 
 With this insight, the second-order term in Eq. 20.6 can be interpreted as “double- bounce” processes involving Bragg scatter from first one and then another wave train,  with the twice-scattered radiowave directed toward the receiver. Of course, there are,  in principle, infinitely many pairs of wave trains that can satisfy this condition, hence,  the integral. 
 13.27.—Gated amplifiers. (a)Switched triode; (b)multicontrol tube switched on second control grid; (c) suppressor switching; (@ screen switching. onealone. 
 PERIOD STAGGER RATIO IS  BEST  AND A GOOD SET OF STAGGER RATIOS CAN BE OBTAINED BY ADDING THE FIRST BLIND SPEED IN 66 "  TO THE NUMBERS  
 CONSTRAINTS METHOD IN NONSTA 
 Curtis: "Solid-State Radar Transmit- ters," Artech House, Norwood, Mass., 1985. 7. DiLorenzo, J. 
 Compensation for Scanned Impedance Variation. The impedance of an element in an array has been discussed and has been shown to vary as the array is scanned. An array that is matched at broadside can be expected to have at least a 2:1 VSWR at a 60° angle of scan. 
    XI  
 310). The latter term denotes targets consisting ofmany independent elements (rain, vegetation) which generally fillthe volume illuminated bya“pulse packet” (Sec. 4.2) completely. 
 DOMAIN  ECHOES MAY BE PROCESSED USING A $&4 TO PRODUCE A SET OF . FREQUENCY 
 Also there is usually less depolarization in a parabolic cylinder than  in a paraboloid fed from a point source. Since a directive feed is used w~th a parabolic cylinder,  leakage through a mesh reflector will cause a higher backlobe than wo~lld a poidi-source feed.  Therefore, solid reflector-surfaces are generally employed. 
 Most propagation effects that are of importance cannot be easily included into the radar  equation. They must be properly taken into account, however, since they can have a major  impact on performance. Further discussion of the effects of propagation on radar is given in  Chap. 
 The antenna beamwidth is assumed  to be approximated by 0, = A/a. [Equation (4.37) is not inconsistent with thesimple derivation  of Eq. (4.36).] If the mean doppler-frequency shift of the clutter echo is perfectly com-  pensated, the limitations on the improvement factor due to clutter spread can be found by  assuming a gaussian spectral shape and substituting the standard deviation of Eq. 
    
 The case where p = 180° (forward scatter) is not covered by the above theorem. The  forward-scatter cross section can be many times the monostatic (backscatter) cross section.  Siegel has shown that the forward-scatter cross section of a target with projected area A is  <J 1 4nA 2 / ,,1. 
 With s~rch  close spacing the phase difference between the signals received in the two feeds is negligibly  small. Any difference in the amplitudes between the two antenna outputs in the arnplitude-  comparison system is a result of differences in amplitude and not phase. The phase-  comparison monopulse, on the other hand, measures phase differences only and is not  concerned with amplitude difference. 
 M DIAMETER REFLECTOR ILLUMINATED BY THREE OFFSET FEEDS  WHICH GENERATE THREE SIDE 
 Target and clutter  models would obviously need to appropriately take into account doppler effects intro - duced by the movement of their equivalent scatterers. 22.10 VESSEL TRACKING SERVICES Radar heads for port control and coastal surveillance systems have some requirements  in common with those for shipborne radars. This originally resulted in many of the  well-known suppliers of shipborne radar getting involved in this area. 
 15.38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 sea clutter for low grazing angles and short pulses in particular. The major problem  of characterizing these features in a manner useful to quantitative predictions is still  being addressed. Perhaps the expression of the scattering properties of the surface in  terms of an intrinsic surface property like its fine-scale curvature might introduce an  organizing principle for the many bits and pieces that presently make up the theory  of sea scatter. 
 This is not an easy task to implement and probably  impossible to make infallible. Basically, the racon needs to build a table of radar sig - natures that it is currently receiving, based on frequency and pulse length. It then  identifies whether high level and lower level pulses of the same signature are being  received and makes the assumption that these are from the same radar. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 Similarly, choice of the waveform frequency and bandwidth can be guided by calcula - tion of the clutter power spectral density as a function of these parameters for any given  sea state, taking into account any information about target course, speed, and RCS. A very important operational consideration here is the potential for an adversary  to exploit the sea clutter spectrum by contriving to place his ship echo at the Bragg  frequency where it would be obscured by sea clutter. 
 Excellent compilations of industry performance have been published  for further insight.19,20 These references outline state-of-the-art power output density  and efficiencies of compound semiconductors from 1 through 100 GHz. Wide Bandgap Semiconductors.  Since the inception of solid-state, Zolper21  draws historical reference to the first, second, and third generation of semiconduc - tor materials as (1) silicon, (2) gallium arsenide or indium phosphide, and the (3)  so-called wide bandgap semiconductors (WBGS). 
 556 INTRODUCTION TO RADAR SYSTEMS  where lj;,. is the angle of arrival measured in the plane of the fence, here assumed to he vertical.  The bistatic radar can measure Vie and S = D1 + D,. 
 ( g–i) Oil Tanker images with processing. The D2 classiﬁcation data set is processed with random crop, divided into two sets: the training data set Dtrain2 (with 14270 samples) and the validation data set Dval2 (with 8400 samples), as shown in Figure 12.     (a) (b) (c)  Figure 12. 
 The combination is known as a passive TR-limiter. The  passive TR-limiter protects the receiver from nearby transmissions even when the fadar is shut  off since it requires no active voltages for either the radioactive-primed TR tube or the diode  limiter. The presence of the diode limiter following the TR tube considerably reduces the spike  leakage, increasing the life of the device itself as well as the receiver front-end it is supposed to  protect. 
 Elbaum: First-Order Statistics of a Non-Rayleigh Fading Signal and Its Detection,  Proc. IEEE, vol. 66, pp. 
 Theextended rangesduringductingconditions meanthatgroundclutterislikelytobepresent atlongerranges.ThiscanputasevereburdenonsomeMTIradarsthataredesigned onthe assumption thatclutterwillnotappearbeyondacertainrange.Thiswillbeparticularly bad withradarswhichcannotcancelsecond-time-around clutter.suchasthosewithpulse-to-pulse staggered pulserepetition frequencies orthosewhichusemagnetron transmitters withrandom starting phasepulsetopulse.Theaccuracy ofprecision rangemeasuring systems thatutilize phasemeasurements. asintheTellurometer (Sec.3.5).alsocanbeaffected bytheevaporation dtICt.JROnthepositive side.theevaporation duct,whenusedwithaproperly sitedantenna, canprovideextended rangeagainstsurfacetargetsorlow-llying aircraftconsiderably beyond that\vhichwouldbeexpected fromauniform atmosphere. Prediction ofrefractive effects.Theeffectofatmospheric refraction onelectromagnetic propa­ gationcanbedetermined fromaknowledge ofthevariation ofindexofrefraction withaltitude overthepathofpropag~tion. 
 30, no. 6, pp. 150 152, June  1. 
 OF 
 Geosc. &  Rem. Sens ., vol. 
  D" DESIGN SIDELOBES MIGHT BE CHOSEN 4HE TERMINOLOGY  N INDICATES  THAT THE FIRST N SIDELOBES ARE HELD TO THE SPECIFIED LEVEL.   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°Ó )T SHOULD BE NOTED THAT FOR A RECTANGULAR ARRAY A DIFFERENT ILLUMINATION MAY BE  CHOSEN FOR EACH PLANE 4HIS IS APPROPRIATE IF THE SIDELOBE REQUIREMENTS IN EACH OF  THE PLANES ARE DIFFERENT 4HE RESULTANT LOSS IN GAIN IS THEN THE SUM IN DECIBELS  OF THE LOSSES IN EACH PLANE4!",%  )LLUMINATION &UNCTIONS )LLUMINATION &UNCTION %FFICIENCY  G 0EAK 3IDELOBE  D""EAMWIDTH   &ACTOR  K ,INEAR ILLUMINATION FUNCTIONS BEAMWIDTH   KK  A DEGREES  A   LENGTH OF ANTENNA 5NIFORM  
 In order to compare the two on the basis of similar coverage, it will be  assumed that a nonscanning monostatic radar is operated at each end of a radar fence. The  monostatic radar requires two transmitters, two receivers, and two antennas to generate the  fence. The bistatic radar also needs two antennas, but only one transmitter and one receiver. 
 B , vol. 8, pp. 213–253, 1960. 
 16.18b, thevector R,represents the contribution from the fixed targets and Rzthat from the moving targets, and Ristheresultant signal. Atthenext pulse, R2changes to R;,and the resultant toR’.The small vector risthe pulse-to-pulse change. Individual moving targets inthe illuminated area are sonumerous that even thelargest issmall insize compared witht heirs urn. 
 Lynch, “Real time radar data processing,” presented at IEEE Solid State Circuits 4.10  Committee, Digital Filtering Meeting, New York, October 30, 1968. 38. D. 
 RANGE RADAR APPLICATIONS GENERALLY REQUIR 
 LOSS  HIGH 
  
 This  is counteracted in part by adaptively increasing the width  of the tracking gate that senses the location of the lead­ ing edge. The addition of adjacent high-resolution sam­ ples to form a wider gate leads to a reduction in noise.  As part of the overall height and wave-height estima­ tion process, the amplitude of the ocean-return signal  is normalized via an automatic gain control loop. 
 The latter is the form of turbulent effect that aircraft encounter at the higher . RADAR CLUTIER ~;f I  altitudes. The convective cell is generally of greater turbulent intensity than the layer, but it  does not extend over as wide an area of space and is not present as often as layers seem to be. 
 VERSUS 
 When only 2 to 4 samples (pulses) are avail - able, a binary integrator should be used to avoid false alarms due to interference. When  a moderate number of pulses (5 to 16) are available, a binary integrator or a mov - ing-window integrator should be used. If the number of pulses is large (greater than  20), a batch processor should be used. 
 provided thelimiting ratio(ratioofvideolimitleveltormsnoiselevel)isaslargeas 2or3.10Otheranalyses ofbandpasslimiters showthatforsmallsignal-to-noise ratio,the reductioninthesignal-to-noise ratioofasine-wave imbedded innarrowband gaussian noiseis n/4(aboutIdB).53However, byappropriately shaping thespectrum oftheinputnoise,ithas beensuggested54thatthedegradation canbemadenegligibly small. Collapsing loss.Iftheradarweretointegrate additional noisesamples alongwiththewanted signal-to-noise pulses,theaddednoiseresultsinadegradation calledthecollapsing loss.Itcan occurindisplays whichcollapse therangeinformation, suchastheC-scope whichdisplays elevation vs.azimuth angle.Theechosignalfromaparticular rangeintervalmustcompete ina collapsed-range C-scope display, notonlywiththenoiseenergycontained withinthatrange interval. butwiththenoiseenergyfromallotherrangeintervals atthesameelevation and azimuth. 
           &#'$ !&  (. £{°£ä  2!$!2 (!.$"//+  IS IDENTICAL TO THAT OF A FLAT PLATE WHOSE PHYSICAL AREA MATCHES THE EFFECTIVE AREA OF THE  CORNER REFLECTOR 4HE MAGNITUDE OF THE ECHO MAY BE DETERMINED BY FINDING THE POLYGO 
 C. Levitt: Radar Range Performance, Hughes Aircraft Co. Tech. 
 If b is the azimuth angle, Vh is the horizontal wind speed, and Vf is the fall speed of the  particles, then the radial velocity at range r is given by  Vr (b) = Vh cos b cos a + Vf sin a (19.60) A harmonic analysis (least square fitting the amplitude, phase, and offset of a sinu - soid) can be used to obtain Vh, the horizontal wind speed, the wind direction where cos  b is maximum, and Vf, the mean particle fall speed all plotted as a function of height.  This technique is referred to as the Velocity-Azimuth-Display (V AD). Browning and  Wexler147 later showed how the V AD technique could be extended to measure other  parameters of the wind field including wind-field divergence and wind-field deforma - tion by employing an extended harmonic or Fourier series analysis. 
 This predefined profile may be stored in memory or be digitally generated by using appropriate constants. The matched filter may be implemented by using a digital correlator for any waveform or else a "stretch" approach for a linear-FM waveform. Digital pulse compression has distinct features that determine its acceptability for a particular radar application. 
 Phase{reqllency planararray..Atwo-dimensional (planar) phasedarraycanutilizefrequency scanning tosteerthebeaminoneangularcoordinate andphaseshifterstosteerinthe. 'Itlf! f:.l.liC'l'RONIC.AI,LY S'1'f:IiRlii) I'ItASI!U ARRAY ANTENNA IN RADAR 335  orthogonal coordinate. Tliis approach is generally easier than using phase sliifters to  scan in both coordinates, but as with any frequency-scanned array the use of the  freqlrency dornain for other purposes is limited when frequency is employed for  bealii-steeririg. 
 .. Wooded terrain (wind lymph). ..........A, cm 9.2 92 3.2 32 3.2 9.2 9.2Voltage ratio ofrms Total echo/rms Buctuation, fixed ~omponent to] db rms variable com- 1 ponent 0 0 0 0 <<1, 0.9 37PRF =500 5 13 s 14 22 34 511000 11 19 14 20 28 39 542000 17 25 20 26 34 46 57 1Sees.6,13to6,21ofVol. 
 VARYING PHASE PHASE MODULATION  0-  OR FREQUENCY MODULATION  &-  4HE ABSOLUTE LEVEL DEPENDS ON THE STRENGTH OF THE SIGNAL CARRIER  ON WHICH THE NOISE SOURCE IS RIDING -ULTIPLICATIVE NOISE SOURCES ARE FREQUENCY INSTA 
 In this case, Z is given by the sixth moment of the particle size distribution, Z = r N(D)D6JD (23.9)%/ o . If the radar beam is filled with scatterers, the sample volume V is given10 ap- proximately by v _ 2^fn (231Q) 8 where 9 and <(> are the azimuth and elevation beamwidths, c is the velocity of light, and T is the radar pulsewidth. Substituting Eqs. 
 Week Space Technol., pp. 62-69, July 14, 1980. 15. 
 Howard Consultant to ITT Industries, Inc. 9.1 INTRODUCTION Typical tracking radars have a pencil beam to receive echoes from a single target and  track the target in angle, range, and/or doppler. Its resolution cell—defined by its  antenna beamwidth, transmitter pulse length (effective pulse length may be shorter  with pulse compression), and/or doppler bandwidth—is usually small compared with  that of a search radar and is used to exclude undesired echoes or signals from other  targets, clutter, and countermeasures. 
 TRACK FUSION SEE &IGURE   UPPER HALF  ASSOCIATES EACH DETECTION TO  THE NETWORKED TRACK  CALCULATED POTENTIALLY USING DETECTIONS FROM ALL RADARS 4HUS   THE ENTIRE STREAM OF DETECTIONS UP TO THE PRESENT  IS POTENTIALLY AVAILABLE TO CALCU 
 The total number of active controls can be reduced to  ch13.indd   6 12/17/07   2:38:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 27. Sommer. H. 
 Sensitivity loss is the amount by which the total  noise (thermal plus phase) exceeds the thermal noise level, as shown in Eq. 4.8. A  gated phase noise to thermal noise ratio of −4 dB results in an approximately 1.5 dB  sensitivity loss. 
 13.74  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13  94. L. R. 
 Rec .,  November 1967, pp. 257–271. 81. 
 D. Bushbeck, “Study of RCS measurements from  a large flat plate,” in Proc. 27th AMTA Conference, Antenna Measurement Techniques Association  Symposium , Newport, RI, October 31, 2005, pp. 
 “Guidelines for the presentation of navigation-related symbols, terms and abbreviations,” Safety  of Navigation Circular 242, International Maritime Organization, London, 2004. 22. “Performance standards for the presentation of navigation-related information on shipborne  navigational displays,” Resolution MSC.191(79), International Maritime Organization,  London, 2004. 
 The N  filters generated by the index k constitute the filter bank. Note that the weights of Eq. (4.13)  and the diagram of Fig. 
 (The chemical recorder has been of more use in sonar than in radar.) The integration improve­ ment was found to be from 2.2 to 2.5 dB per doubling or the number of pulses, which is  consistent with .the computations for the theoretical integration improvement obtained by  Marcum43 for ideal postdetection integration. The results for the chemical recorder (curve A)  are slightly better than the B-scope (curve B) due to the imperfect memory of the cathode-ray  tube B-scope as compared with the permanent· memory of the chemical recorder. Similar  results were noted for the improvement in a conventional PPI when the pulses were displayed  side·by-side. 
 $*                
 Rule 2.  Synchronize ac-dc and dc-dc power conditioners to harmonics of the  PRF. When ac-dc and/or dc-dc power conditioners are used for voltages applied to  transmitting devices, the frequency (and its harmonics) of the converter must be atten - uated sufficiently so that they do not modulate the phase of the transmitted pulses. 
 March,1959. j5.Gustafson. B.G.,andB.O.As:SystemProperties ofJumping Frequency Radar,PhilipsTelecom. 
 Inconsidering systems ofthis type, wewill first describe anumber of specific systems and foreach system the relevant theory, leaving any generalizations until the end ofthe chapter. This appears tobethe only feasible course since ofmany possible systems few, ifany, will be familiar tothe average reader, and general theory would therefore be scarcely comprehensible. The reader should bewarned that inthedescriptions ofthese specific systems quantitative information will belacking onvarious points, even onimportant ones. 
 Ghazifard, A.; Akbari, E.; Shirani, K.; Safaei, H. Evaluating land subsidence by ﬁeld survey and d-insar technique in Damaneh city, Iran. J. 
 Remote Sens. T echnol. Appl. 
 The amount of calculation is greatly reduced, so the speed can also be improved. Momentum [ 36] is a commonly used acceleration technique in gradient descent method. Stochastic gradient descent with momentum can be expressed as v=β×v−α·∇θJ/parenleftBig θ;x(i);y(i)/parenrightBig (2) θ←θ+v (3) βis momentum coefﬁcient. 
 Improving the Accuracy of Two-Color Multiview (2CMV) Advanced Geospatial Information (AGI) Products Using Unsupervised Feature Learning and Optical Flow. Sensors 2019 ,19, 2605. [CrossRef ][PubMed ] 6. 
 5.7 ACQUISITION  i\ tracking radar must first find and acquire its target before it can operate as a tracker.  Therefore it j9.-.usually necessary for the radar to scan an angular sector in which the presence  of the target is suspected. Most tracking radars employ a narrow pencil-beam antenna. 
 ALTITUDE WIND SHEAR HAZARDS FROM DOPPLER WEATHER  RADAR AN ARTIFICIAL INTELLIGENCE APPROACH v * !TMOS /CEAN 4ECHNOL   VOL   P n    ! , 0AZMANY  * " -EAD  3 - 3EKELSKY  AND $ * -C,AUGHLIN  h-ULTI 
 — or 2/l~=—. T(20) ‘l’his condition determines thenecessary attenuation inthelayer inorder that theemergent wave ~rill produce complete cancellation. Itisquali- tatively obvious that the attenuation for each passage must become smaller asthereflection atthefront surface becomes greater. 
 George: Detection of Targets in Non-Gaussian Sea Clutter, 1EEE Tru~rs., vol.  AES-6, pp. 620-628, September, 1970. 
 Detection ranges of ASV Mk. VI against a submarine were typically about 19 nmi at 1000 ft, only slightly greater than for ASV Mk. III (after TRE maintenance, as reported for ASV Mk. 
 Unfortunately, the accuracy of any phase-noise mea- surement that depends on a delay line is proportional to the length of the delay. Long delays imply difficulty in maintaining sufficient signal amplitude to make satisfactory measurements. Incidentally, as noted above, many measurement techniques can be altered to provide a valid source-stabilization method. 
 Graffeuil, and J. Obregon, "Applications of GaAs MESFET's," Artech House, Norwood, Mass., 1983, pp. 157-207. 
 SYNTHETIC APERTURE RADAR  17.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 Let us assume that the radar transmits a step-frequency waveform consisting of iden - tical groups of pulses, each group consisting of N ( 1) “single-frequency” pulses  of width t. Within a pulse group, the frequency of a pulse is ∆f greater than that of  the previous pulse, and the radar transmits ( PRF)/N groups per second, where PRF  is the pulse repetition frequency. The waveform bandwidth is ( N − 1) ∆f  1/t. 
 -   - ) 3KOLNIK  )NTRODUCTION TO 2ADAR 3YSTEMS  .EW 9ORK -C'RAW 
 Iloughtori. I:. W.. 
 72 PROPERTIES OFRADAR TARGETS [SEC. 37 radar camouflage ofU-boats. The type ofabsorber that was actually put into service was ofthe interference kind. 
 East, “The microwave properties of precipitation particles,” Q. J. R. 
  
 There is even an option to remove spurs (spurious frequencies), occurring during the measurements, from the calculations and from the data. All this comes at a considerable cost, not all of which is monetary. One's ability to understand any laboratory technique and its inherent reliability are usually inversely related to complexity. 
 56,p.2098,November, 1968. 15.Anand,Y.,andW.J.Moroney: Microwave MixerandDetector Diodes, Proc.IEEE,vol.59,pp. 1l82-lt90, August,1971. 
 118. Bass. F. 
 Another methodofprocessing therangeorheightinformation fromanaltimeter soasto reducethenoiseoutputfromthereceiverandimprove thesensitivity usesanarrow-bandwidth low-frequency amplifier withafeedback looptomaintain thebeatfrequency constant. 30.34 Whenafixed-frequency excursion (ordeviation) isused,asintheusualaltimeter, theheat frequency canvaryoveraconsiderable rangeofvalues.Thelow-frequcncy-amplifier hand­ widthmustbesufficiently widetoencompass theexpected rangeofbeatfrequencies. Sincethe bandwidth isbroader thanneedbetopassthesignalenergy,thesignal-to-noise ratiois reduced andthereceiversensitivity degraded. 
 49. “Passive system hints at stealth detection silent sentry—A new type of radar,” Aviation Week and  Space Technology , November 30, 1998, pp. 70–71. 
 TED LINE IS THE 3).2 FOR THE QUIESCENT ABSENCE OF ADAPTIVITY  PATTERN IT MIMICS THE RECIPROCAL OF THE SIDELOBE AND MAIN 
 3. Morgan, D. P.: Surface Acoustic Wave Devices and Applications, Ultrasonics, vol. 
 48, pp. 92–95, 1993. 61. 
 M. Dillard, “Adaptive detection algorithms for multiple-target situations,”  IEEE Trans ., vol. AES-13, pp. 
 CHAPTER  SIX  RADAR TRANSMITTERS  6.1 INTRODUCTION  The radar system designer has a choice of several different transmitter types, each with its own  distinctive characteristics. The first successful radars developed prior to World War 11  employed the conventional grid-controlled (triode or tetrode) vacuum tube adapted for opera­ tion at VHF, a relatively high frequency at that time. The magnetron oscillator, which  triggered the development of microwave radar in World War II, has been one of the most  widely used of radar transmitters, especially for mobile systems. 
 The transmit duty cycle is maximized  to increase detection range. The receiver may be range gated to match the bandwidth  of the transmit waveform, but range measurement is not attempted. A VS dwell will consist of a single look at a given PRF. 
 B. (ed.): "Microwave Magnetrons," MIT Radiation Laboratory Series, vol. 6, McGraw-  Hill Book Co., New York, 1948. 
 LFM Waveform Examples.  Figure 8.3 shows the magnitude of the autocorrela - tion function as a function of relative time delay τ for doppler shifts‡ of –0.5 MHz,  0 and 0.5 MHz, pulsewidth T = 10 µs, swept bandwidth B = 1 MHz, and LFM slope  a = B/T = 0.1 MHz/µs. A doppler shift of fd = B/2 = 0.5 MHz causes the peak of the  correlation function to move to t  = fdT/B = 5 µs. 
 93, pt. IIIA, pp. 1554-1558, 1946. 
 N    WHERE 3I IS THE SUM AT THE  ITH PULSE OF THE LAST  N PULSES AND  XI IS THE ITH PULSE 4HE PER 
 Thusthemechanism bywhichthesystemsaturates depends onthenatureofthetargetsituation.. The AN/FPS-85 is a large UHF phased-array radar located at Eglin Air Force Rase,  Florida which was designed for the detection and tracking of earth-orbiting objects  a satellite^)."^ It was one of the first major applications of a coniputer-controlled multifilnc-  tion phased-array radar. The system computer consists of two IRM System 3601651 central  processors, each with 13 1,072 thirty-two-bit words of core memory and a basic atitf time of  14 11s. 
 TUNED PROCESSOR 7HEN THEY DO APPEAR  AZIMUTH AMBIGUITIES ARE RELATIVELY EASY TO IDENTIFY &IGURE   BECAUSE THEY ARE WEAKER GHOST  DUPLICATES OF IMAGE FEATURES THAT WERE COLLECTED THROUGH THE MAIN BEAM AND  THEREFORE  AT EARLIER OR LATER POSITIONS ALONG THE IMAGE STRIP 4HE AZIMUTH SHIFT OF THE AMBIGUITIES RELATIVE TO THE CENTRAL IMAGE IS AN INTEGRAL MULTIPLE OF  $82 F 6 0 L  3#  WHICH IS THE SPATIAL  e  &OR A UNIFORMLY ILLUMINATED APERTURE  THE  
 D" MAINLOBE WIDTHS AND FILTER MATCHING LOSS FOR (AMMING WEIGHTING ARE APPROXIMATELY THE SAME AS FOR n 
 Ro_v. Mer.:or. Soc., vol. 
 However, the standard deviation of the estimates are 100 percent greater than the  Similarly the standard deviation of the double-loop integrator using the maxi-  mum value as the estimator produces a standard deviation 50 to 100 percent greater than the  optimum. The two-pole filter of Fig. IO.lOc, on the other hand, has a standard deviat~on 15  percent greater than optimum, and the estimator based on the maxin- dm value has a constant  bias.66 Its relatively good dngle-estimating accuracy, good detection performance, along with  the relative simplicity of a feedback integrator makes the two-pole filter a gooddchoice as an  automatic detector for scanning radars. 
 SIDERED TO HAVE FINITE  0 T  AND SO THE RANGE OF  FREQUENCIES THAT CAN BE PRESENT IS LIMITED BY THE PULSE  AS WELL AS BY THE ANTENNAS AND THE MAXIMUM VELOCITY !NOTHER EXAMPLE IS SHOWN IN &IGURE   4HIS IS THE SMALL ILLUMINATED AREA FOR A NARROW 
 GROUND INTERFACE  &)'52%   3IMULATION OF ! 
 Most parabolic-reflector antennas seem to have  f /D ratios ranging from 0.3 to 0.5.  Reflector surfaces. The reflecting surface may be made of a solid sheet material, but it is often  preferable to use a wire screen, metal grating, perforated metal, or expanded metal mesh. 
 l, 1950.  16. Lee, Y. 
 AP- 10, pp. 35 1-352, May, 1962.  141. 
 171  . INDEX  AERIALS, Hertz, 525 Marconi,  52; rotating, $5  Afterglow, 61  Altimeters, 162 et seq.  Appleton, Sir E. 
 PULSE BASIS  WHICH IS OFTEN THE CASE IN PULSE 
 ALTITUDE RADAR TARGETS IN THE PRESENCE OF MULTIPATH v  )%%% 4RANS  VOL !%3 
 Asthesize ofa signal peak(which means, really, signal-plus-noise) will notbeessentially altered bytheaveraging provided thesignal occurs atthesame place on successive sweeps, itwill beeasier todetect asmall signal onthetrace c than ona. More than this wecannot say without elaborate analysis of thestatistical problem. Such analysis can becarried through bywell- known methods (see Chap. 
 GROUND ATTACKs 0LANETARY EXPLORATIONs 3HORT RANGE SURVEILLANCE 4RANSMITTER 
 ECCM comprises those radar actions taken to ensure effective use of the electromagnetic spectrum despite the enemy's use of elec- tronic warfare. The topic of EW is extremely rich in terms, some of which are also in general use in other electronic fields. A complete glossary of terms in use in the ECM and ECCM fields is found in the literature.3'6'8 9.3 ELECTRONICWARFARESUPPORT MEASURES ESM is based on the use of intercept or warning receivers and relies heavily on a previously compiled directory of both tactical and strategic electronic in- telligence (ELINT). 
 A50percent savinginthetotalnumber ofphaseshiftersmightbe·had.Thinning inthismanneralsogives risetophaseerrorswhichcauseadeterioration intheradiation pattern. Adaptive antennas.142-151 Anadaptive antennasensesthereceivedsignalsincidentacrossits aperture andadjuststhephaseandamplitude oftheaperture illumination toachievesome desiredperformance, suchasmaximizing thereceivedsignal-to-noise ratio.Thenoisemaybe eitherinternalreceivernoiseorexternalnoise,asfromjammers. Clutterechoesorinterference fromotherelectromagnetic radiations canalsobeminimized byadaptive antennas. 
 (a) (b) FIG. 13.9 Example of clutter behavior with wind speed and grazing angle—average of data at 10 GHz29 and 13.9 GHz.28 (a) Vertical polarization, (b) Horizontal polarization.WINDSPEED (knots) WIND SPEED (knots) . sea clutter on wind speed that can be established with any confidence from ex- isting data, although most investigators would probably agree that the behavior of microwave sea clutter with wind speed at intermediate grazing angles can be roughly described as follows: for light winds (less than 6 to 8 kn) sea clutter is weak, variable, and ill defined; for intermediate winds (about 12 to 25 kn) it can be described roughly by a power law of the type found in Fig. 
 This is an example of a  front feed. It is well suited for supporting horn feeds, but it obstructs the aperture.  Two basic limitations to any of the feed configurations mentioned above are aperture  blocking and impedance mismatch in _the feed. 
 Shaping the  underside of tile 2D transmitting antenna to minimize the energy illuminating the surface can . 546 INTRODUCTION TO RADAR SYSTEMS  reduce the angular error. The effective receiving area of the interferometer is usually less than  that of the conventional radar reflector antenna with which it is used. 
 These early radars were  known as wave-interference equipments but were the same as what would now be called  bistatic radar. Taylor and Young of the Naval Research Laboratory first demonstrated bistatic  radar for the detection of ships in 1922. Their work was disclosed in a patent issued in 1934.~~  The early experiments with wave-interference (bistatic) radar led to the development of mono-  static radar in the late 1930s in both this country a11d abroad. 
 9 -3 and 9- 4.  [4] F.X. Hofele, A new class of CFAR Algorithms, Proceedings of the International  Radar Symposium IRS’98, Munich, Sept. 
 The effect of ECM on a single radar can seldom be considered in  isolation since it is seldorn that a single radar acts as an entity in itself. A military radar is  almost always in support of a weapon system. The question is not whether a single radar can  operate without degradation, but whether the weapon system of which the radar is a part can  f~tlfill its mission in spite of liostile ECM. 
 Thisisaccomplished by separating thesidelobeclutterfromthemain-beam clutterbydoppler filtering. Thefiltered signaladaptively adjuststheaperture illumination tominimize thesidelobes inthosedirec­ tionsfromwhichclutterappears. Thecoherelitside/vhecallce/er (Sec.14.5)isaformofadaptive antenna thatusesasmall number ofauxiliary elements toadaptively placenullsinthedirection ofexternal noise sources, Itisanexample ofasuccessful application oftheprinciples oftheadaptive antenna thatutilizesonlyarelatively fewnumber ofadaptive elements. 
 At the critical gradient, the wave will propa - gate at a fixed height above the ground and will travel parallel to the Earth’s surface.  Refraction between the normal and critical gradients is known as superrefraction . Superrefractive conditions are largely associated with temperature and humidity  variations near the Earth’s surface. 
 In Figure 25.17, we transform the system of Figure 25.15 to make it more computa - tionally efficient. We begin with the structure in Figure 25.17 a, which shows the filtering  in detail using t  to indicate each clock-interval delay. The location of the one nonzero  coefficient in the real part hI(n) of the Figure 25.16 impulse response corresponds to an  odd-numbered delay, so hI(n) is realized using a single delay and some number of double  delays. 
 554–568, 1968.  8. D. 
 G. Grasso and P. F. 
 2. Guinard, N. W., J. 
             
 Green, B. A., Jr.: Radar Detection· Probability with Logarithmic Detectors, IRE Trans., vol. IT-4,  pp. 
 There are three main problems which must be addressed in connection with these large interfering signals. The first is the need to prevent lock on the clutter signal and its harmonics. Clutter in some geometries may be spectrally very narrow, resembling a target signal. 
 Sensors 2019 ,19, 346 of shapes in the real experiment. We set all the dihedrals as dihedral B in the Gotcha experiment. As can be seen in Figures 2and 14, the RCS curves of these two kinds of shapes are similar in both the simulation and the real experiment. 
 LUTION ACHIEVABLE OVER UNCODED WAVEFORMS "ECAUSE THE RANGE RESOLUTION IS PRO 
 L Pryce: The Calculation or Field Strengths over a Spherical Earth. J. IEE. 
 DOPPLER CELL IS GIVEN BY   0.4 M N.4FDM &! RU &2 ¤ ¦¥³ µ´§ ©¨ ¨¨¨¶ ¸· ···  LN      WHERE .RU    NUMBER OF INDEPENDENT RANGE SAMPLES IN THE OUTPUT UNAMBIGUOUS 
 Therefore the rms error  in the time-delay measurement for a" rectangular" pulse of width r. limited to a bandwidth B,  is approximately  J  bTa ~ (4B;/NJ112 bandwidth-limited rectangular pulse ( 11.20)  The pulse width r in the above expression is that of the perfectly rectangular pulse before band  limiting. It is a good approximation to the width of the band-limited pulse when Br is large. 
 vol.AES-6,pp.522-527, July,1970. 14.Harrington, J.V.,andT.F.Rogers: Signal-to-noise Improvement through Integration inaStorage Tuhe,Proc.IRE,vol.38,pp.1197-1203, October, 1950. 15.Mentzer, J.R.:"Scattering andDiffraction ofRadioWaves," Pergamon Press,NewYork,1955. 
 McKee. D. A.: An FM MTI Cancellation System, MIT Lincoln Lab. 
 as siqttrtr :c,I.o. .i'lic advar~tagc of irsilig at1 ixl>ression slicli as Eq. (13.1) to describe  distributed surface clutter is tliat it is i~sually independent of tlic area A,. 
 G. R. Valenzuela and R. 
 LOBED ANTENNA PATTERN IN ADDITION TO THE CONVENTIONAL MONOPULSE BEAMS SUM  DIFFERENCE IN AZIMUTH  AND ELEVATION  CAN IMPROVE THE ESTIMA 
 Make r i,tthe residual signal after titerations, and initialize r i,0=s/prime i. (2) Obtain index λtby solving the following formulas: Mixed sum norm: λt=arg max k∈{1,···,PQ}2 ∑ i=1/parenleftBig/vextendsingle/vextendsingle/vextendsingle/angbracketleftBig ri,t−1∗,Ai,k/prime/angbracketrightBig/vextendsingle/vextendsingle/vextendsingle/parenrightBig , (18) 160. Sensors 2018 ,18, 3750 Mixed Euclidean norm: λt=arg max k∈{1,···,PQ}2 ∑ i=1/parenleftBig/vextendsingle/vextendsingle/angbracketleftbig ri,t−1∗,Ai,k/prime/angbracketrightbig/vextendsingle/vextendsingle2/parenrightBig1/2 , (19) Mixed inﬁnite norm: λt=arg max k∈{1,···,PQ}/parenleftbigg max i∈{1,2}/vextendsingle/vextendsingle/angbracketleftbig ri,t−1∗,Ai,k/prime/angbracketrightbig/vextendsingle/vextendsingle/parenrightbigg , (20) where, Ai,k/primeis the kcolumn vector in perception matrix. 
 Themillimeter regionisdefinedfrom40GHz (7.5mmwavelength) to300GHz(1.0mmwavelength).70 Although Kgband(35GHz)corre­ spondstoawavelength of8.6mm,andradarsatthatbandmightqualifybysomedefinition as belonging tothemillimeter waveregion,thetechnology atKgbandisbasically thatofthc microwave region.Atfrequencies aboveKgbandmostmicrowave techniques areinadequate, sothatnewtechnology isrequired. ThusKgbandshouldnotusuallybeincluded aspartof themillimeter-wave region. Advantages ofmillimeter waves.Interest inmillimeter-wave applications stemsfromthe specialproperties exhibited byradaratthesefrequencies, aswellasfromthechallenge of exploiting aregionofthespectrum notwidelyused.Themajorattributes ofthemillimcier­ waveregionofinteresttoradararethelargebandwidth, smallantenna size,andthecharacter­ isticwavelength. 
 There may be important benefits  when a radar is able to operate at more than one frequency.2 Frequency agility  usually  refers to the use of multiple frequencies on a pulse-to-pulse basis. Frequency diversity   usually relates to the use of multiple frequencies that are widely separated, sometimes in  more than one radar band. Frequency diversity might operate at each frequency simul - taneously or almost simultaneously. 
  IS A NORMALIZING TERM THAT  AS WE  WILL SEE IN A MOMENT  PLAYS A KEY ROLE 4HE  5 FUNCTION FOR A CERTAIN PAIR OF ANGLES  P  E  DETERMINES  AFTER COMPARISON WITH A SUITABLE THRESHOLD  IF A TARGET IS DETECTED  4HE SAME 5 FUNCTIONAL WHEN SCANNED ACROSS A SUITABLE SET OF  P  E  ANGLE VALUES  PROVIDES  BY MEANS OF %Q   THE TARGET $O! ESTIMATE 7E REFER TO %Q  AND  ITS PRACTICAL IMPLEMENTATION AS THE GENERALIZED MONOPULSE TECHNIQUE 4HE ALGORITHM NEEDS THE ESTIMATION OF THE DISTURBANCE COVARIANCE MATRIX  -D   WHICH IS OBTAINED BY THE RADAR ECHOES CORRESPONDING TO RANGE CELLS ADJACENT TO THE CELL UNDER TEST WHERE A POTENTIAL TARGET IS SOUGHT 4HE MAXIMUM  OF THE 5 FUNCTIONAL  CAN BE ESTIMATED BY AN EXHAUSTIVE SEARCH IN THE RANGE OF VALUES OF INTEREST OF  P  E   OR BY USING A FAST RECURSIVE ALGORITHM  4HE RECURSION CAN BE INITIALIZED WITH THE  ANGULAR COORDINATES OF THE MAIN 
 DISH IS A HYPERBOLIC 
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     PP n    & " $YER AND . # #URRIE  h3OME COMMENTS ON THE CHARACTERIZATION OF RADAR SEA ECHO v IN   $IG )NT )%%% 3YMP !NTENNAS 0ROPAGAT  *ULY n    $ % "ARRICK  * - (EADRICK  2 7 "OGLE  AND $ $ #ROMBIE  h3EA BACKSCATTER AT (&  )NTERPRETATION AND UTILIZATION OF THE ECHO v 0ROC )%%%  VOL     # # 4EAGUE  ' , 4YLER  AND 2 ( 3TEWART  h3TUDIES OF THE SEA USING (& RADIO SCATTER v  )%%%    * /CEANIC %NG  VOL /% 
 C. J.: 1)olpli-Cliebysliev Excilaliori Coefficient Approximation. IEEE Tratts., vol. 
 3  ! 
 IMPREGNATED PLASTIC  FOAM CUT IN THE FORM OF PYRAMIDS )T EXHIBITS OPTIMUM PERFORMANCE WHEN THE PYRA 
 The received  pulse train of finite duration t0 has a frequency spectrum (which can be found by taking the  Fourier transform of the waveform) whose width is proportional to 1/t0. Therefore, even if the  clutter were perfectly stationary, there will still be a finite width to the clutter spectrum because  of the finite time on target. If the clutter spectrum is too wide because the observation time is  too short, it will affect the improvement factor. 
 The typical slant range to the intended  scene may be 800 km and more. Thus, the upper bound on the PRF should not be set  by the range to the scene, but rather by the range width of the area to be imaged. As a  consequence, the resulting high PRF will generate a sequence of pulses at any moment  that are distributed between the radar and the scene. 
 TRIBUTIONS THAT ARE NOT REQUIRED TO BE GAUSSIAN IN FORM 4HUS  IN A PARTICLE FILTER  EVEN MULTI 
 20.3 (Continued) (c) Effect of refraction on radar horizon, (d) Angular error due to refraction. velocity in the medium in question. One effect of refraction is to extend the radar distance to the horizon, as suggested in Fig. 
 R.: Quaternary Codes for Pulsed Radar, IRE Trans., vol. IT-6, pp. 400-408, June, 1960. 
 FED SERIES ARRAY  AFTER * &RANK Ú !RTECH (OUSE    A  CENTER 
 MOTION IMPROVEMENT FACTOR 4HE CONSTANT  + IS THE  NOISE NORMALIZATION FACTOR FOR THE -4) FILTER  +    FOR SINGLE DELAY AND  FOR DOUBLE  DELAY  ' P   IS THE TWO 
 Theoretic Aspects of Synthetic Aperture Generation. In generating a syn- thetic antenna, the returns from a number of spatial positions must be combined. In doing this, one usually wishes to apply weighting to the signals for synthetic antenna pattern sidelobe-level control; in the case of focused synthetic antennas, one also wishes to adjust the phases of the signals before combination. 
 Murakami, T.: Optimum Waveform Study for Coherent Pulse Doppler, RCA Final Kept., prepared for Office of Naval Research, Contract Nonr 4649(00)(x), Feb. 28, 1965. AD641391. 
 This  demonstrates a general rule: to maintain a low Pfa in various environments, adaptive  thresholding should be placed in front of the integrator. If the noise power varies from pulse to pulse (as it would in jamming when fre - quency agility is employed), one must CFAR each pulse and then integrate. While the  binary integrator performs this type of CFAR action, analysis23,24 has verified that the  ratio detector shown in Figure 7.14 is a better detector. 
 TO 
 Noise Models.  The widely used reference on noise is the International Radio  Consultative Committee (CCIR) Report 322.105 This report is based upon mea - surements made at 16 locations throughout the world. The measurement and data  analysis were performed to exclude individual collection site local thunderstorm con - tributions. 
 532 13.16 The “Resolved Time Base” Method ofPPI Synthesis . 534 13.17 Resolved-current PPI 538 13.18 The Method ofPre-time-base Resolution. 544 13.19 The Range-height Indicator. 
 Although thepowerdelivered totheantenna wasonly6kW,arangeof50miles-the limitof thesweep-was obtained byFebruary. TheXAFwastestedaboardthebattleship NewYork, inmaneuvers heldduringJanuaryandFebruary of1939,andmetwithconsiderable success. Rangesof20to24kiloyards wereobtained onbattleships andcruisers. 
 It reduces exactly to Eq. (23.39) for large SIN and for narrow spectra, i.e., p(7) « 1. The reader is referred to Zrnic44 for further details regarding the estimation of other moments of the doppler spectrum. 
 74. E. Eichblatt, Test and Evaluation of the Tactical Missile , Washington, DC: AIAA, 1989,   pp. 
 M VERTICAL RESOLUTION SOUNDING DATA 4HE ANTENNA DIAMETER  LIMITED BY THE LAUNCH VEHICLE SHROUD  IS  M  WHICH SUPPORTS ACROSS 
 VARYING INPUTS TO THE FREQUENCY MODULATION &-  AND PHASE MODULATION 0-  PORTS &)'52%  $IRECT $IGITAL 3YNTHESIZER BLOCK DIAGRAM 
 Antennas and Propagation , vol. AP-34, no. 3, pp. 
 DUTY 
 TIONS 4HE TARGET REPORTS GENERATED BY A SURVEILLANCE RADAR ARE PROCESSED TO FORM TARGET TRACKS 4HE KEY FEATURES OF A SURVEILLANCE RADAR ARE THE DETECTION RANGE IN CLEAR  CLUTTER  AND JAMMING ENVIRONMENTS  THE ACCURACY AND RATE OF THE EXTRACTED DATA  AND THE FALSE 
 1. Monopulse Radar," Artech House, Inc., Dedham, Mass., 1974 (a  collectior~ of 26 rcprints from tlie literature of monopulse radar).  19. 
 / 
 A modification of the helix known as the ring-bar  circuit has been used in TWTs to achieve higher power and efficiencies between 35 and 50  percent.1u2 The Raytheon QKW-1671A, which utilizes a ring-bar circuit, has a peak power  of 160 kW, a duty cycle of 0.036,''pulse width of 70 µs, gain of 45 dB, and a 200 MHz band­ width at L band. This tube is suitable for air-se~rch radar. Similar TWTs have been used in  phased-array radar. 
 Inthe case of scanning effects this leads, with thehelp ofEq. (10), tothefollowing sim- plerelationship: Lo=:(scanning), (25)s where nisthe number ofpulses per beamwidth. Inthe case ofwind effects, wehave, from Eq. 
 29. 100. Paddison, F. 
 , Ê " 
 PASS CHARACTERISTIC 4HE RESONANT FREQUENCY OF THE ANTENNA AND SERVOSYSTEM STRUCTURE INCLUDING THE  STRUCTURE FOUNDATION  WHICH IS A CRITICAL ITEM  MUST BE KEPT WELL ABOVE THE BANDWIDTH OF THE SERVOSYSTEM  OTHERWISE THE SYSTEM CAN OSCILLATE AT THE RESONANT FREQUENCY ! FACTOR OF AT LEAST  IS DESIRABLE FOR THE RATIO OF SYSTEM RESONANCE FREQUENCY TO SERVO BANDWIDTH (IGH RESONANT FREQUENCY IS DIFFICULT TO OBTAIN WITH A LARGE ANTENNA  SUCH AS THE !.&01 
 D. R. Carter, J. 
 Witli :I different value of current pulse, a different value  of rclii:ilictit 1ii;igrieti7.:ttio1i car1 be obtained and therefore a different phase shift. In this  tri:iliricr. tl~e ferrite toroici is basically ari analog device that can provide any phase increment. 
 This is not strictly true in all cases and must be qualified, as the  performance of some radars can be stongly affected by the presence of meteorological particles  (hydrometeors). In general, radars at the lower frequencies are not bothered by meteorological  or weather effects, but at the higher frequencies, weather echoes may be quite strong and mask  the desired target signals just as any other unwanted clutter signal.  Whether the radar detection of meteorological particles such as rain, snow, or hail is a  blessing or a curse depends upon one's point of view. 
 The value 1 represents anisotropic pixels, and 0 represents isotropic pixels. In the Circular SAR image, the pixel size is much smaller than the target size. A whole target or a structure of a target consists of many pixels. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing.  RADAR DIGITAL SIGNAL PROCESSING  25.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 the Nyquist bound. 
 1972.  19. Prinsen, P. 
 The decision must depend, toaconsiderable extent, onthe relative importance ofusing beacons fornavigation and foridentification. For anidentification system, itisobviously necessary tohave but one rela- tively simple type ofbeacon and torequire that theidentifying radar sets beaccommodated toit. For navigational purposes, the requirements ofthe airplane become relatively more important. 
 W. H. Peake and S.T. 
 The repre - sentation of voltage in offset binary is given by  E = k[(bN−1)2N−1 + bN−12N−2 + bN−22N−3 + ⋅ ⋅ ⋅ + b120] (3.35) The Gray code10 is also used in certain high-speed A/D converters in order to  reduce the impact of digital output transitions on the performance of the A/D con - verter. The Gray code allows all adjacent transitions to be accomplished by the change  of a single digit only. Delta-Sigma Converters. 
  
 The costs listed here refer only to tube costs. Also see comments un- der "Control Electrodes," below. The comments listed apply roughly to both de- velopment costs and unit costs. 
 A four-port circulator is shown with the fourth port ter-  minated in a matched load to provide greater isolation between the transmitter and the receiver than  provided hy a three-port circulator.  Circulator and receiver protector. The ferrite circulator4' is a three- or four-port device that  can, in principle, offer separation of the transmitter and receiver without the need for the  conventional duplexer configurations of Figs. 
 Angle ^ 1 deg.» = Noise Ground Range (nmi) Ground Range (nmi) FIG. 24.20 Radar performance estimate; January, 1800 UTC. (a} SSN - 10. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar.  METEOROLOGICAL RADAR  19.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 and to suppress ground clutter. 
 2007 ,45, 3533–3551. [ CrossRef ] 11. Jun, S.; Yang, L.; Xiaoling, Z.; Ling, F. 
 H. A. Crowder, “Ground clutter isodops for coherent bistatic radar,” IRE Nat. 
 A far more reliable method of ship recognition is inverse synthetic  aperture radar (ISAR).16,72 The basic notion is that the motion of a rigid object can be  resolved into a translation and rotation with respect to the line of sight to the target. The  rotation gives rise to a differential rate of phase change across the object. The phase  history differences can be match filtered to resolve individual scatterers in a range cell. 
    
 The latter is unattractive as it destroys the symmetry that may be required to assure uniformity of time delays to cancel the FM noise of the LO. Even in the simplest version the symmetry is far from complete, as the signal channel must handle signals over a wide range of amplitudes while the reference channel carries a signal of uniform amplitude. IF Amplifier. 
 SITUATED STORMS 4HIS IS A CONSEQUENCE OF THE ON 
 NADIR ANGLE OF n FOR A GREAT MAJORITY OF THE DATA TAKES   POLARIZATION OPTIONS TO BE  SINGLE 
 (Prior  knowledge of the characteristics of the trajectory can be incorporated in the model, as, for  example, when the trajectory is known to be ballistic.) If the difference between the pred~ction  and the measurement is zero, no adjustment is made and the antenna mount is pointed  according to the stored prediction. If they do not agree, the target trajectory prediction 1s  changed until they do. Thus, the pointing of the antenna is made open-loop based on the  stored target-trajectory prediction updated by the radar measurements. 
 Geosci. Remote Sens. 2015 ,53, 6718–6734. 
  
 Vincent: Radar-Tracking Accuracy lncrcast:d, Electro11ics, vol. 37, pp. 73 75. 
 Quart.J.Roy.Meteor.Soc.,vol.88, pp.485-495. 1962. 1.38.Zhuk.M.S..andYu.8.Molochkov: "Proektirovanie Linzovykx, Skaniruyushchikx. 
 The minimum detectable signal Smin and the  ~arget cross section cr are both statistical in nature and must be expressed in statistical terms. 16 INTRODUCTION TO RADAR SYSTEMS  Other statistical factors which do not appear explicitly in Eq. (2.1) but which have an effect on  the radar performance are the meteorological conditions along the propagation path and the  performance of the radar operator, if one is employed. 
 By deforming the ring inward from  mechanical motion applied to the free-hanging ends of the ring, the tuning of the cavity is  changed. The Raytheon QKH 1763 X-band coaxial magnetron tunes in this manner over a  100-MHz range at rates up to 200 Hz. Electronic tuning is also possible.49  6.3 KLYSTRON AMPLIFIER  The klystron amplifier is an example of a linear beam tube, or 0-type tube. 
 Finally thescattering cross section varies with time; this introduces anadditional modulation which broadens each ofthereturned sidebands byanamount depending ontherate ofthe fluctuation. (All this isforasingle target. Usually there aremany targets, inwhich case the above specification isfurther complicated byasummation over alltargets.). 
 The troposphere extends from the Earth’s surface to an altitude  of 8 to 10 kilometers at polar latitudes, 10 to 12 kilometers at middle latitudes, and  up to 18 kilometers at the equator. It is characterized by a temperature decrease with  height. The point at which the temperature ceases to decrease with height is known as  the tropopause . 
 4. Murakami, T., and R. S. 
 l'l~e cornpitted briglittiess temperatures of Fig. 12.1 1 do not agree in detail with tliose  prcsctited by otli~rs.~'~~l~~~ 7'11~ fact tliat SLIC~~ cot~iputations made by different ar~thors do not  nlwitys ngrcc precisely riccd r~ot be a liniitatiori to tlie radar systems engineer. Disagreements  oftcri rcsi~lt f1oti1 tllc ovc~.sirilplifyitlg tiatilrc of tlie assuniptions or in tlie rnodel itsed it1  formulating tlie calculations. 
 34$ 
 [ CrossRef ] 7. Hwang, C.; Yang, Y.D.; Kao, R.; Han, J.C.; Shum, C.K.; Galloway, D.L.; Sneed, M.; Hung, W.C.; Cheng, Y.S.; Li, F. Time-varying land subsidence detected by radar altimetry: California, Taiwan and north China. 
 Title. 11. Series. 
 608- 618,  October, 1949.  23. IEEE Standard 686-1977: "IEEE Standard Radar Definitions," Nov. 
 Performance ojtheAN/.4 PS-lO.—The completed set shows per- formance meeting the initial requirements. Scope-map comparisons that display theusual overland performance ofthesetatlow and medium altitude are shown inFigs. 15”11 and 15.12. 
 The  leaves and branches of trees, for example, might have considerably different reflecting proper­ ties at K0 band (,.l = 0.86 cm), where the dimensions are comparable with the wavelength, from  those at VHF (l = 1.35 m), where the wavelength is long compared with the dimensions.  The general expression for improvement factor for an N-pulse canceler with N1 = N -I  delay lines is61  (4.27)  Antenna scanning modulation. 46.49-52 As the antenna scans by a target, it observes the target  for a finite time equal to t0 = n8/ J, = 88/()1, where n8 = number of hits received, J, = pulse  repetition frequency, ()8 = antenna beamwidth and (J1 = antenna scanning rate. 
 3.3.3 Receiver unit The receiver unit, type 3516 or 3515, took the IF signal at 13.5 Mc/s from the T 2R unit and provided the main IF ampli ﬁcation and ﬁltering (using a chain of six VR65 pentodes and coupled IF transformers). The IF bandwidth at −3 dB was 3.5 Mc/s. Valves 1 and 3 in the IF chain were suppressed during transmission to prevent residual breakthrough from the TR switch from saturating the ampli ﬁer. 
 Powerful MST radars are operated at many laboratories around the world. Major facilities are located at Kiruna, Sweden; the Massachusetts Institute of Technology in Cambridge, Massachusetts; Arecibo, Puerto Rico; Jicamarca, Peru; and at the University of Kyoto in Japan. These clear-air radars receive energy backscattered from index-of-refraction inhomogeneities due to atmospheric turbulence. 
 Figure1.22illustratesacaseinwhichechoesarebeingreceivedfromfour targets, but only three pips are painted on the PPI. Targets A and B arepaintedasasinglepipbecausetheyarenotseparatedbymorethanonebeamwidth; targets C and D are painted as separate pips because they areseparated by more than one beam width. In as much as bearing resolution is determined primarily by horizontal beam width, a radar with a narrow horizontal beam width provides betterbearing resolution than one with a wide beam.CRT Spot Size The bearing separation required for resolution is increased because the spot formed by the electron beam on the screen of the CRT cannot befocused into a point of light. 
 157.Ward,H.R.,C.A.Fowler,andH.I.Lipson:GCARadars:TheirHistoryandStateofDevelopment. Prot'.IEEE,vol.62,pp.705-716, June,1974. 158.Ethington, D.A.:TheAN[fPQ-36 andAN[fPQ-37 Firefinder Radars,Imertlational Cunference RADAR-77, Oct.25-28,1977,lEE(London) Publication no.155,pp.33-35. 
 RACY OF THE ) AND 1 REPRESENTATION OF THE ORIGINAL INPUT DATA BECOMES AN IMPORTANT  CONSIDERATION !NY DC OFFSET  AMPLITUDE IMBALANCE  QUADRATURE PHASE ERROR  OR NONLIN 
 PulseUS.C-UIMethods. —Pulse methods have been much more highly developed than those using c-w transmission, partly because ofthepulse- circuit experience available atthe Radiation Laboratory, and partly because the r-fequipment available during most ofthework was ofthe amplitude-modulation rather than the frequency-modulation type. However, much can besaid infavor ofthepulse methods from afunda- mental standpoint, regardless ofthetype ofcarrier modulation. 
 46. Scholtz, R. A., J. 
 On the other hand, the maximum value, though it has a constant bias, has estimates that are 100 percent greater than the lower bound. Furthermore, the exponential weighting function essentially destroys the radar antenna sidelobes. Because of these problems, the feedback integrator has lim- ited utility. 
 Staprans. and R. Symons: Wide Band High Power Klystrons, IRE  WESCON Con,,. 
 Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters.  SOLID-STATE TRANSMITTERS  11.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 FIGURE 11.14  Common microwave power-combining circuit topologies that are used to provide  isolation among adjacent parallel amplifiers in a corporate combining structure FIGURE 11.15  Contours of power lost to the isolation load resistor of an isolated power com - biner for a range of amplitude and phase imbalances between two combined amplifiers. With an  amplitude imbalance of 1 dB and a phase imbalance of 30 °, approximately 0.31 dB of power will  be lost to the isolating termination of the power combiner.Contours of Vectoral Power Lost 5101520253035404550 0 1 2 3 4 5 6 7 8 Amplitude Imbalance (dB)Phase Imbalance (deg) 0.1dB1.1dB 1.0dB 0.9dB 0.8dB 0.7dB 0.5dB 0.4dB 0.3dB 0.2dB0.6dB1.2dB ch11.indd   21 12/17/07   2:25:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 This restricts the sector which is blanked by main-beam jamming and also provides a strobe in the direc- tion of the jammer. Strobes from two or three spatially separated radars allow the jammer to be located. 9.8 RECEIVER-RELATEDECCM Jamming signals that survive the antenna ECCM expedients can, if large enough, saturate the radar processing chain. 
 BAND  
 SPREAD FUNCTION 03&  OF A  MOVING POINT TARGET AFTER CLUTTER CANCELLATION  AND &IGURE  B SHOWS THE FINAL SIMU 
 45-51, March,  1952.  29. Fuller, W.: "An Introduction to Probability Theory and Its Applications," 2d ed., vol. 
 ELEMENT PHASE MODULATION WAS USED  WITH A HEIGHT AMBIGUITY OF  KM )N LATER PHASES OF PROCESSING  DOPPLER FREQUENCY ANALYSIS NARROWED THE EFFECTIVE FOOTPRINT TO  KM BY  KM 4HE ALTIMETER OPERATIONS INTERLEAVED WITH THOSE OF THE IMAGER  RESULTED IN THE FIRST RADAR ALTIMETRIC MAP OF THE NORTHERN   OF 6ENUS COMPRISED OF MORE THAN   INDIVIDUAL MEASUREMENTS 4HE COMMUNICATIONS SYSTEM USED A DEDICATED  M RADIO DISH ANTENNA 4HE 6ENERA SPACECRAFT WERE IN APPROXIMATELY  ^ 
  USES THREE FIXED 
 The jet engine caused modulation is called Jet Engine  Modulation (JEM) spectral modulation lines. The high-frequency-noise modulation  affects scan-type tracking radars, as described later, and gives some information as  to the type of aircraft. Effects of Amplitude Scintillation on Radar Performance. 
 n _____ ~ ~' n f!_' C ~" 11 ~--~' L_J L_: LI\__; L_  ~ .. Runomb---1 I I  I I  I I  t =O t =1/t p t = 2/fp t == 3/tp  Time (or range) __,._  (a)  ~ 8 C 4  (\ (\ (\  Range - (b)  n A& (\  Range -...+- ( C)  Figure 2.26 Multiple-time-around echoes that give rise to ambiguities in range. (a) Three targets A, Band  C. 
 Knowing the shape of the antenna patterns, the measurement of the ratio of signals in  the two beams allows the target elevation angle to be deduced. A similar technique4u1 utilizes  sum (I:) and difference (L\) patterns whose ratio l\q;:Js symmetrical. Just as in off-axis tracking,  the a·11Tenna boresight · is locked at some elevation angle. 
 Anechofromamoving targetproduces aseriesofpulses whichvaryinamplitude according tothedoppler frequency. Theoutputoftherangegatesis stretched inacircuitcalledtheboxcargenerator, orsample-ami-hold circuit,whosepurpose is toaidinthefilteringanddetection processbyemphasizing thefundamental ofthemodulation frequency andeliminating harmonics ofthepulserepetition frequency (Sec.5.3).Theclutter­ rejection filterisabandpass filterwhosebandwidth depends upontheextentoftheexpected clutterspectrum.. 118 INTRODUCTION TO RADAR SYSTEMS  Phase Ronge  detector NO. 
 The general construction and layout can be seen from Fig. 12.16. Separate AFC and signal mixers areincorporated inthe receiver; the choke joints forconnection tothe r-fsystem can be seen intheside view. 
 TO 
 PLICATED PHENOMENOLOGY OF SEA CLUTTER SPECTRA -EASUREMENTS OF MICROWAVE CLUTTER SPECTRA FOR REAL SEAS HAVE BEEN REPORTED IN THE  LITERATURE FOR AIRCRAFT MEASUREMENTS OF THE SPECTRAL SHAPE ALONE    FIXED 
 Millimeter-Wave Solid-State Power Sources. Solid-state power in the millimeter-wave frequency range is generated from low-power oscillators or negative-resistance amplifiers. The most promising results have been obtained from IMPATT diodes or Gunn diodes. 
 It gave much increased detection ranges, but at the price of increased sea returns and greater vulnerability to interception by radar warning receivers (see discussion below). With the advent of centimetric ASV, interest in ASV Mk IIA receded and production was curtailed toonly 12 sets ( ﬁgures 2.7and2.8). Figure 2.6. 
                                          .   05,3% #/-02%33)/. 2!$!2   n°ÓÇ #LUTTER REJECTION WITH PULSE COMPRESSION WAVEFORMS IS DUE TO THE GREATER RANGE RESO 
 Figure . FIG.636,-LHTR transmitter-receiver-power-supply unitused inAN/APG-15 andother sets. 6.37 shows an“x-ray” view oftheSCR-,584 with theantenna elevated into operating position. 
 Óä°x{  2!$!2 (!.$"//+  OTHER INFORMATION SUCH AS TARGET ALTITUDE %STIMATES OF AIRCRAFT TARGET ALTITUDE ARE  VERY USEFUL  BUT SKYWAVE RADAR HAS NOT PROVED TO BE A RELIABLE MEANS OF OBTAINING  ACCURATE ESTIMATES  4HE PROBLEM OF CONVERTING FROM RADAR COORDINATES TO GEOGRAPHICAL COORDINATES IS  REFERRED TO AS  COORDINATE REGISTRATION #2   $OZENS OF #2 TECHNIQUES HAVE BEEN EXPLORED   INCLUDING I  INFERENCE FROM A REGIONAL IONOSPHERIC MODEL  II  DEPLOYING A NETWORK OF REPEATERS OR BEACONS IN THE RADAR FOOTPRINT  III  CORRELATING COASTLINES WITH LAND CLUTTER    SEA CLUTTER BOUNDARIES IN THE RADAR DATA  IV  CORRELATING OTHER PARAMETERS SUCH AS SCATTER 
 Thus, kj,should beabout 1600 forthis particular wind speed. Ingen- eral, itiseasy toobtain therequired figure forAj,,but notforn,witho’ut sacrifice elsewhere. Scanning fluctuations arethe principal difficulty in MTI design. 
 The numbers along the zero error Iine,indicate the track time in minutes. (From Linde.46) . 174 INTRODUCTION TO RADAR SYSTEMS  image. 
 Although power is a well-understood characteristic of the usual radar waveform consisting of a rectangular pulse, with more complicated waveforms the total sig- . nal energy is often a more convenient measure of waveform detectability. It also is more appropriate for theoretical reasons. 
 He joined Thales (then EMI Electronics) in 1967 and worked on a wide range of radar and EW projects, with a particular research interest in maritime radar and sea clutter. He is author and co-author of over 80 journal and conference papers, a book on sea clutter and several patents. He was appointedMBE in 1996 for services to the UK defence industry and is a Fellow of the Royal Academy of Engineering, Fellow of the IET, Fellow of the IMA and Fellow of the IEEE. 
 Inoneexperimental design,4M ten discrete phase-shifter elements werereplaced withasingleferrite-loaded aperture whose properties wereexternally controlled toscanthebeamradiated byafive-wavelength, X-band antenna. Otherelectronic phaseshifters. Inaddition totheferriteanddiodedevices, therehavebeen othertechniques suggested forelectronically varyingthephaseshift.Thetraveling-wave tube. 
 Karelitz, and L. A. Turner (eds.): "Radar Scanners and Radomes." MIT  Radiation Laboratory Series. 
 Rain and chaff clutter may also be large when the main beam illuminates a rain or chaff cloud. Motion due to winds may displace and/or spread the return in frequency. Altitude-line clutter, which is due to ground clutter at near normal incidence directly below the radar platform, is at zero doppler if there is no vertical com- ponent of platform velocity. 
 Li, W.; Chen, J.; Yang, P .; Sun, H. Multitemporal SAR Images Change Detection Based on Joint Sparse Representation of Pair Dictionaries. In Proceedings of the 2012 IEEE International Geoscience and Remote Sensing Symposium, Munich, Germany, 22–27 July 2012; pp. 
 Although thepulse techniques described here were largely worked out with the magnetron inmind, the information presented isintended tobegenerally applicable toany oscillator orpower-consuming load. The discussion will belimited tomethods peculiarly well adapted topulse powers inthe range ofafew kilowatts uptoseveral megawatts, and to pulse durations inthe range from one-tenth toseveral microseconds. The primary aim ofthebalance ofthis chapter istogive the designer a feeling forthe over-all problem, and toassist him indeciding among the compromises required toachieve awell-balanced design. 
   6IKING 
 26.2 THE EARTH’S ATMOSPHERE1 Structure and Characteristics.  The Earth’s atmosphere is a collection of many  gases together with suspended particles of liquids and solids. Excluding variable  components such as water vapor, ozone, sulfur dioxide, and dust, the gases of nitrogen  and oxygen occupy about 99% of the volume, with argon and carbon dioxide being the  next two most abundant gases. 
 46.49-52 Astheantenna scansbyatarget,itobserves thetarget forafinitetimeequaltoto=nBIjp=8BI{)s'wherenB=number ofhitsreceived, jp=pulse repetition frequency, 8B=antenna beamwidth and{}s=antenna scanning rate.Thereceived pulsetrainoffiniteduration tohasafrequency spectrum (whichcanbefoundbytakingthe Fouriertransform ofthewaveform) whosewidthisproportional tol/to.Therefore, evenifthe clutterwereperfectly stationary, therewillstiltbeafinitewidthtotheclutterspectrum because ofthefinitetimeontarget.Iftheclutterspectrum istoowidebecause theobservation timeis tooshort,itwillaffecttheimprovement factor.Thislimitation hassometimes beencalled scanning fluctuations orscanning modulation. Thecomputation ofthelimitation totheimprovement [actorcanbe[oundinamanner similartothatoftheclutterfluctuations described previously. Theclutterattentuation isfirst foundusingEq.(4.21),exceptthatthepowerspectrum ~(f)describing thespectrum produced byt~efinitetimeontargetisused.Theclutterattenuation is C-s;~(f)df A-J;~(f)IH(f)12df (4.28) whereH(f)isthefrequency response function oftheMTIsignalprocessor. 
 BEHAVED STATISTICAL TAILS   AND TO MAINTAIN A C ONSTANT FALSE ALARM RATE   THE THRESHOLD MUST BE RAISED FOR ENDOCLUTTER TARGETS 4HE OUTPUT OF THE DOPPLER FILTER BANK MIGHT BE THOUGHT OF AS A TWO DIMENSIONAL RANGE 
 ITED TO THE DESIGN PRINCIPLES  DRIVEN BY THE THREAT REQUIREMENTS  OF THE DEDICATED RADAR TRACKER   4HE ENSUING SUBSECTION WILL REFER TO MULTIFUNCTIONAL PHASED 
 B. Patton, Jr., “Orbit determination from single pass doppler observations,” IRE Transactions  on Military Electronics , pp. 336–344, April–July, 1960. 
 arXiv 2011 , arXiv:0812.2635v3. 11. Eilek, J.A.; Hankins, T.H. 
 Further, only those signals which come inarange interval ofabout 50yd immediately following therange forwhich the marker issetaresent to theinput oftheangle-error measuring circ~lits.. 210 THEGATHERING ANDPRESENTATION OFRADAR DATA [SEC. 6.15 Circuits have been devised and tested which provide automatic track- inginrange, aswell asinangle, but itappears that thejudgment ofthe range operator isofdefinite value inthe operation ofthisequipment. 
 Zakurdayev, and V . I. Poognin, “Multiple-beam  klystron amplifiers: performance parameters and development trends,” IEEE Trans ., vol. 
 41Radar Cross Section (RCS) • Typical values: • Fundamental equation for the RCS of a “electrically large” perfectly reflecting surface of area Awhen viewed directly by  the radar • Expressed in decibels relative to a square meter (dBsm): -40   -20 0 20 40 dBsmm2 0.0001 0.01 1 100 10000  INSECTS BIRDS CREEPING  &  TRAVELING  WAVESFIGHTER  AIRCRAFTBOMBER  AIRCRAFTSHIPS 2 24Aπ σλ≈ σdBsm =10log 10(σ). 42RCS Target Types • A few dominant scatterers (e.g., hu ll) and many smaller independent  scatterers • S-Band (2800 MHz), horizontal polarization, maximum RCS = 70  dBsm . 43RCS Target Types • Many independent random scatte rers, none of which dominate  (e.g., large aircraft) From Skolnik • S-Band (3000 MHz)• Horizontal Polarization • Maximum RCS = 40 dBsm. 
 (c)c5 c0 –c2 c4 – c6 c8 –c10 FIGURE 25.18  Negated-alternate-signs version of Q filter coefficients0.5 0c0 –c2 c4 –c6 c8 –c10 ch25.indd   14 12/20/07   1:40:11 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 
 The four tlucti~a-  tion models are as follows:  Case I. The echo pulses received from a target on any one scan are of constant amplitude  throughout the entire scan but are independent (uncorrelated) from scan to scan. This  assumption ignores the effect of the antenna beam shape on the echo amplitude. 
 &REQUENCY 4RANSFORMS FOR 2ADAR )MAGING AND 3IGNAL !NALYSIS    .ORWOOD  -! !RTECH (OUSE    , #OHEN  h4IME 
 T rans. Res. Board 2018 ,2672 , 76–86. 
 EST PROBABILITY OF VISIBILITY 0 6  )N THE EXAMPLE  THE PRODUCT 06  OF THE RANGE 02   AND DOPPLER  0$  TARGET VISIBILITY PROBABILITIES FOR A SINGLE 02& PEAKS AT APPROXIMATELY   AND THUS THE OTHER 02&S MUST FILL IN TO REACH  CLEAR OR HIGHER 4HERE ARE SEVERAL &)'52%  -EDIUM 02& RANGE 
 If the target cross section were to vary during this observation time, the change  might he erroneoilsly interpreted as an angular-error signal. The monopulse radar, on the  other ttand. detern~ines the-angular error on-the-.basis of a single pulse. 
 SYMMETRIC IMPULSE  RESPONSE CONDITIONS DEFINED BY %Q    HN    H-  
 A.: Influence of Precipitation on the Electrical Properties of Wire Mesh Sirrfaces,  Radiotekhnika, vol. 11, no. 9, pp. 
 Anyone who has seen a CRT in an oscilloscope or a  television set will be familiar with the large pear- or  bottle-shaped bulb. Tubes used in radar range from  about four inches in diameter to those with a tube~-  width of over a foot. Types of fluorescent screen vary  in colour, sensitivity, and other factors according to the  radar display needed, and the electrode construction of  the tubes varies according to the deflection of the electron  beam needed to produce a requisite display. 
 (21.7) is desired, focusing must be used. Focusing removes the restriction on synthetic aperture length that would otherwise apply. 21.3 RADARSYSTEMPRELIMINARIES Whether or not synthetic aperture generation is used, a number of components are required for a radar system. 
 xrernent while the pair of frequencies f2, fl are chosen close to resolve  the ambiguities in the l; , fl nieasurenient. Likewise, if further accuracy is required a fourth  frequency can be transmitted and its ambiguities resolved by the less accurate but unambiguous  roc:isr~reri~tnt ohtnitied fro111 the three frequencies,f,, f2, f,. As more frequencies are added. 
 DIMENSIONAL CASE   THIS QUANTITY IS AVERAGED OVER THE SEA SLOPE ANGLE DISTRIBUTION P@    YIELDING   SY SY A AA      
 Direct digital synthesizers (DDSs) can be used either to generate LO frequencies directly  or to generate modulated waveforms prior to upconversion. When pulse-to-pulse phase  coherence is required, the starting phase is reset to zero at the start of each pulse. If all the  LO frequencies used are multiples of the pulse repletion frequency, the resulting phase  will be the same for each pulse. 
 Theuseofan,thecrosssection perunitarea,todescribe theradar scattering fromclutter, impliesthattheclutterisuniform andindependent oftheradar­ resolution-cell area.Inreality,landclutterisnotuniform. Radarswithhighresolution might actually becapable ofbetterperformance thanpredicted onthebasisofa'Rayleigh clulter modelandaaOindependent ofradarresolution. Aradarwithanarrowpulsewidthornarrow beamwidth not onlyseeslesslandclutterthanaradarwithlargerpulsewidthorbeam­ width,butitcanseetargetsinthoseareaswhereclutterislessthantheaverage, iftheseareas canberesolved. 
 In principle, the automatic tracking radar discussed in Chap. 5 is another example of an  adaptive antenna. The aperture illumination is sensed by a conical scan or monopulse feed and  the antenna is repositioned to maintain the signal-to-noise ratio a maximum. 
 RANGE '02 SYSTEMS  ARE OPERATING IN THE  NEAR 
 Avideo switch provides fortime sharing between the video signals and the synchronizing pulses inorder that theformer shall not interfere with the latter. Initsnormal position, the flip-flop holds switch bin the state that passes pulses. Firing ofthe flip-flop by apulse delayed by 30psec from the modulator pulse reverses the video switch allowing echo signals topass. 
 of Oceanic Enginerring,\vol. OE-I, no 2, pp 68-71, November, 1976  11. Moore, R. 
 Thus,bytransmitting a number offrequencies andusingtheangleerrorcorresponding tothatfrequency withthe largestsignal.itispossible toeliminate thelargeangleerrorsassociated withglint.39,40Those returnsoflowamplitude and,hence,ofhigherror,areexcluded inthistechnique. Insteadof selecting onlythelargestsignalforprocessing, theindicated position ofthetargetateach frequency canbeweighted according totheamplitude ofthereturn.40Onlyasmallnumberof frequencies isneededtoreducesubstantially theglinterror.Thereduction inrmstracking errorbyprocessing onlythatsignal(frequency) withthelargestamplitude isapproximatel y40 (5.6) where (1,isthesingle-frequency glinterrorandNisthenumberoffrequencies. Thetracking errorwillnotdecrease significantly formorethanfourpulses.Eachofthefrequencies mustbe separated byatleastM~,asgivenbyEq.(5.3). 
 I>f:I ECI ION OF RADAR SIGNALS IN NOIS1 377  Likelihood-ratio receiver. The likelitlood ratio is an important statistical tool and may be  defiried as the ratio of the probability-detisity function corresponding to signal-plus-noise,  prn(r), to the probability-density function of noise alone, pn(t)).  It is a rlieasure of how likely it is that the receiver envelope 1) is due to signal-plus-noise as  compared witti noise alone, It is a random variable and depends upon the receiver input. 
 ATED FROM A MULTIPLICITY OF AMPLIFIERS DISTRIBUTED ACROSS THE APERTURE %LECTRONICALLY CONTROLLED ARRAY ANTENNAS CAN GIVE RADARS THE FLEXIBILITY NEEDED TO PERFORM ALL THE VARI 
 Thecostofthecomputer hardware andsoftware ofamultifunction radarsystemcanhea significant fraction ofthetotalsyslemcost.Compuler syslemdesignmustbeintegral withthat oftheradarhardware itself.Thedevelopment ofthesoftware canbeanespeciallY-flcmanding taskthatcannotbeconsidered minor. 8.10OTHER ARRAY TOPICS Hemispherical coverage.123·125Asingleplanarphased-array antenna mighttypically provide coverage ofanangularsector±45°fromthearraynormal; however, itispossible toachievea scancoverage of±60°orgreater.Theamount ofscandepends onthelossofgain,theamount ofbeambroadening, andtheriseinsidelobes thatcanbetolerated. Thefrequency rangeover whichtheantenna mustoperate andtheVSWRthatcanbeaccepted alsodetermine howfar thebeamcanbescanned. 
 Doppler frequency estimation and the Cramer-Rao bound. IEEE T rans. Geosci. 
 R. Graf: The Reduction of Radar Glint by Diversity Techniques, IEEE Trans., vol.  AP-19, pp. 
 Itvaries directly with the bandwidth Bofthe receiver, assuming that Bisproperly adjust edforthe pulse length, and, toagood approximation forthe problem under consideration, itvaries inversely with thesquare root ofthenumber ofpulses perscan onthetarget. Acceptable values foruand Sti. arenow reasonably well established, and, since other quantities determining R-,can bereadily measured, Eq. 
 TION CAUSED BY THE AIR 
 # 3!2 OF #HINA   "OTH OF THESE RADARS USE THE  
 Berry, and B. Steer, “State-of-the-art W-band extended interaction klystron for  the CloudSat program,” IEEE Trans ., vol. ED-52, pp. 
 A value of y = -16 dB in Eq. (25.20) fits the monostatic data within about 2 dB. Using y = -16 dB in Eq. 
 The present section considers the possibility of scanning the  beam over a limited angle with a fixed reflector and a movable feed. It is much easier to  mechanically position the feed than it is to position the entire antenna structure. In addition,  large fixed reflectors are usually cheaper and easier to manufactirre than antennas which must  be moved about. 
 82, pp. 235–262, 1997. 37. 
 The m independent images are then combined non­ coherently into a single image. It has been suggested that the noncoherent combining of  images o.f lesser resolution produces a better image with less speckle than a ~ngle image of  greater resolution.11' 17  If the SAR is mapping a scene in which there are moving objects such as cars or trains, the  resulting image will be smeared in range and shifted in the along-track dimension due to the  radial motion of the object. The image also will be defocused in the along-track dimension  because of radial acceleration or cross-range velocity of the object.8 These effects can cause a  distortion and displacement of the moving-target image. 
 6.50  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 low frequency reference. They also provide the capability for wide-bandwidth chirp  waveforms that cannot be generated directly using available DDS devices. Frequency  multipliers operate as shown in Figure 6.25, by multiplying the phase of the input  signal by the integer multiplication factor M. 
 The development of radar in the Soviet Union was quite  similar to the experience elsewhere. By the summer of 1941 they had deployed operationally a  number of 80-MHz air-search radars for the defense' of Moscow against the German  invasion.14 Their indigenous efforts were interrupted by the course of the war.  Thus, radar developed independently and simultaneously in several countries just prior to  World War 11. 
 Prengaman, R. E. Thurber, and W. 
 When θBW1is small, the Doppler bandwidth is approximately BW1=2v λ/bracketleftbigg sin(θ+θBW1 2)−sin(θ−θBW1 2)/bracketrightbigg ≈2v λcosθ·θBW1 (1) O X  v A BC  ii SPXRY Y AAAAA  X  CCCC  BBBBBT T Figure 3. Multi-angle SAR signal model. Then, the echo data of target Pifrom a side-looking beam is obtained. 
 6 
 4 miles* Azimuth Accuracy . 2 degrees Operating Frequency  . 104-112 MHz Antenna  . 
 Dr D. Taylor worked on a  branch of ground-control using as the radar eye the  ingenious ‘PPI’ (‘plan position indicator’) cathode-ray  tube, described later in this book. Radar was adapted  to searchlights, the system being largely the work of  L. 
 forward or aft of the aircraft is mapped. It is necessary to position the antenna beam so that the maximum of its radiation pattern points in the desired squint direction. Moreover, it is usually necessary to modify the signal processors to take into account the average doppler frequency shift that occurs when the antenna points in a direction other than normal to the flight path. 
 Any use is subject to the Terms of Use as given at the website. Airborne MTI.  AIRBORNE MTI  3.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 3.8 PLATFORM-MOTION COMPENSATION,  FORWARD DIRECTION The previous sections discussed the compensation for the component of platform  motion parallel to the antenna aperture. TACCAR removes the average component  of platform motion perpendicular to the aperture. 
 [ CrossRef ] 2. Fornaro, G.; Reale, D.; Seraﬁno, F. Four-dimensional SAR imaging for height estimation and monitoring of single and double scatterers. 
 SUM 
 Zotti: The Detection Perrorrnance of the Siebert and Dicke-Fix CFAR Radar  Detectors, IEEE Trans., vol. AES-7, pp. 706-709, July, 1971. 
 OUT SPECTRUM FROM A RADAR TRANSMITTER IS TO SHAPE  OR TAPER  ITS WAVEFORM  SUCH AS BY USING A TRAPEZOIDAL SHAPE  A GAUSSIAN 
 Ê 
 IEEE, vol. 57,  pp. 1788-1789, October, 1969. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 21.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 SNR because the spectrum of the sampling pulse is a poor match for that of the  received pulse. 
 --+ - '.r Phose sh~flers  set for  receive -  dwell N Phase sh~f ler  orders - ! computer 1,  colculotes '-.  phose orders  for dwell N  326INTlWIHJCTION TORADAR SYSHMS CommonJ datafor .dwell(N+1) CommunICationsRadarreturn bulfer I:, Mo.range ful'-data dwell(N-1) fromdwellData (N-l) I Command I routed,,: I / I ~~J~~lr-.iJ~. _~~-,l_"-,i__-,"_-,!_I'_CJ-Dr---I'-r--'L Phoseshlfler orders -Tmnsmlsslan of command data10 radartordwellN Beam stee(lng~ - computer -----~ calculates ~~""- phoseorders fordwellNTransmission of dala-dwell(N-1) Phoseshrflers sWitched for transmitI' Phoseshifters selfor ..recelve- dwellN- Radar Iransmll/receive operationTransmitted ..pulseMaXimum range ..: Dwell(N-ll OwellN Figure8.31Representative command/response sequence. 
 Beam Scanning and Target Tracking. Because radar antennas typically have directive beams, coverage of wide angular regions requires that the narrow beam be scanned rapidly and repeatedly over that region to assure detection of targets wherever they may appear. This describes the search or surveillance function of a radar. 
 Much experimentation was done, however, with thephase- shifted pulse method ofsynchronization (Sec. 17.6), and with the 100-Mc/sec frequent y-modulated r-fequipment ofSec. 1713. 
 Reed, C. N. Ericksen, and M. 
 Allofthese may be used inconjunction with ground, ship, orairborne radar sets, orwith spe- cial interrogator-responsors. The following combinations have proved useful sofar: Ground Radar, 1.Shipbome beacons. This combination isofuse principally for identification ofparticular ships since, ingeneral, the radar echo from aship isdistinct enough. 
 RADAR CLUTHR 471 radar-crass-section dellsityratherthantheradarcrosssectionaswasdescribed forconven­ tionaltargetsinSec.2.7.Forsurfaceclutll:racrosssectionperunitareaisdefined as (I (J= (tJ.l) where (Jeistheradarcrosssectionrromthearea:Ie•Thesymbol (J0isspoken. andsometimes written. assiqllw :l'/'O.Theadvantage orusinganexpression suchasEq.(13.1)todescribe distributcd surraccc1uttcristhatitisusuallyindependcnt orthearcatie.Forvolume dis­ tributed clutteracrosssectionperunitvolume. 
 (Its output is useful, however, in some MTI radars for  providing a map of the clutter.) The first null of the filter response occurs when the numerator  is zero, or when/= 1/NT. The bandwidth between the first nulls is 2/NT and the half-power  bandwidth is approximately 0.9/NT (Fig. 4.23). 
 Also, if frequency selection had been made with a 2-MHz granularity instead of the 1 MHz used, the SNR would be reduced by only a decibel or so. The performance-estimating aids that follow come from analyses as described above. After calculations as for oblique sounding, a range-ordered table of pa- rameters is made. 
 MALIZATION 4HIS WAS THE BASIC PRINCIPLE OF THE SO 
 Even if the importance of an environmental parameter has been recog- nized, it is often difficult to measure it with accuracy under real-sea conditions, and there are practical and budgetary limits to obtaining open-ocean measure- ments in sufficient variety to develop any really meaningful statistical models of . clutter. Little wonder that many aspects of sea clutter remain frustratingly ill de- fined. 
 13.6. The radar wavelengths are usually too short to be  responsive to these long water waves, but the effect of such waves is noted by the tilting  of the smaller water waves which are resonant with the incident radar energy. The tilting  effect of the large waves is especially important at low grazing angles since the grazing angle  is determined not only by the angle the radar energy makes with the mean sea surface, but  also by the angle of the resonant waves that ride on the large wave structure. 
 It is an art to get a good tracker optimized for all situations, over a variety of  vessel speeds, and to maintain an appropriate indication of change in heading without  excess latency. Over-damped systems may give an apparently stable indication of the  track of a target but can be very inaccurate when a target changes heading. From the  point of view of safety of navigation, the change in heading is often the more impor - tant parameter. 
 4.6 has had wide application. Mognetron  oscillator  4.2 DELAY-LINE CANCELERS  The simple MTI delay-line canceler shown in Fig. 4.4 is an example of a time-domain filter. 
 6, ,1977.  22. Murnford, W. 
 AIRBORNE MTI  3.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 on the beam shoulder. Step-scan compensation usually requires the difference-pattern  peaks to be near the nulls of the sum pattern to match. Grissetti et al.13 have shown that for step-scan compensation the improvement factor  for single-delay cancellation increases as a function of the number of hits at 20 dB/ decade; for the first-derivative∗-type step-scan compensation, at the rate of 40 dB/ decade; and with first- and second-derivative compensation, at the rate of 60 dB/decade. 
 PULSE CORRELATION IN THE RADAR PROCESSOR THEN VERY EFFECTIVELY BLOCKS INTERFERENCE FROM OTHER RADARS  ALBEIT WITH A SMALL BUT GENERALLY ACCEPTABLE DEGRADATION IN DETECTION PERFORMANCE !FTER THE LIMITER  THE ,.&% IS PRECEDED BY A BANDPASS FILTER TO REDUCE THE EFFECTS  OF OUT 
 Sensors 2019 ,19, 3344      (a) ( b)  Figure 7. Range compressed ISAR signal obtained after summation of signals in all frequency channels: (a) real part; ( b) imaginary part. Figure 8. 
 RELATED DYNAMIC RANGE OF RECEIVED SIGNALS !T CLOSE RANGE  34# CLASSICALLY FOLLOWS AN INVERSE FOURTH POWER LAW  MERGING TO AN INVERSE CUBIC LAW IN THE REGION WHERE SEA CLUTTER DOMINATES  IN ACCORDANCE WITH BASIC THEORY "ECAUSE TRANSITION RANGE IS A FUNCTION OF ANTENNA HEIGHT  A SETTING FOR THIS MAY BE NEEDED WHEN THE SYSTEM IS ORIGINALLY INSTALLED 4HE OPERATORS MANUAL SEA 
 ¤ ¦¥³ µ´ 4646P XRP YRSIN SIN COS44P  
 63. P. Lacomme, J. 
 Thus, a single basicradar system can be visualized in which the functional requirements areessentially the same as for all speciﬁc equipments. The functional breakdown of a basic pulse-modulated radar system usually includes six major components, as shown in the block diagram,ﬁgure 1.13. The functions of the components may be summarized asfollows: Thepower supply furnishes all AC and DC voltages necessary for the operation of the system components. 
 DETECTED PULSE IN THE  JTH RANGE CELL AND  M IS THE NUMBER  OF REFERENCE CELLS 4HE DENOMINATOR IS THE MAXIMUM 
 = wave- length.1'92-95 ters (simple centers such as flat plates, reflex centers such as corner reflectors, skewed reflex centers such as a dihedral with corner T^ 90° and stationary phase regions for creeping waves). When the wavelength is small compared with the target dimensions, these complex target models approximate many aircraft, ships, ground vehicles, and some missiles. The targets can be composed of con- ducting and dielectric materials. 
 The transmit - ter stabilization necessary for good operation of an unstaggered MTI is a significant  challenge. To stabilize the transmitter sufficiently for pulse-to-pulse or dwell-to-dwell  stagger operation is considerably more difficult. Typically, pulse-to-pulse staggering  is used with MTI processing, whereas dwell-to-dwell staggering is used with MTD  (filter bank) processing. 
 THE NATURE OF RADAR 3  range might result. Echoes that arrive after the transmission of the next pulse are called  second-time-around (or multiple-time-around) echoes. Such an echo would appear to be at a  much shorter range than the actual and could be misleading if it were not known to be a  second-time-around echo. 
 The system may be combined with mechanical  rotation of the antenna, giving vertical-switched scanning for 3D coverage. Much  greater complexity is required for a system switching beams in both planes. Multiple Simultaneous Beams . 
 Hannan5 © IEEE 1961 ) ch09.indd   8 12/15/07   6:07:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 
 LOOK RESOLUTIONS ARE  M  
 In fact, bistatic-radar detection of  aircraft with point-to-point communications systems has often been reported in the literature.  Perhaps the most common manifestation of the principle of the bistatic radar is the rhythmic  flickering observed in a TV picture when an aircraft passes overhead, especially if the television  receiver is tuned to a weak channel.  The inherent geometry of the bistatic radar is more suited to a fixed (nonscanning)  fencelike coverage as in Fig. 
 For a more comprehensive treatment,  see Barton and Ward.72 The sidelobes predicted by Table 13.1 are for antennas that  have perfect phase and amplitude across the aperture. To allow for errors, aperture  illuminations are often chosen to provide peak sidelobes below those required. For  example, if the antenna specification calls for −40 dB sidelobes, a Taylor illumination  that provides −45 dB design sidelobes might be chosen. 
 The direction and %.-< .:.Film-. speed ofthis chart motion can be-- Screeo:=’. adjusted bythe operator sothat P.‘%Cthe chart and the radar display top stay inregister asthe v~ssel FIG. 
 (/2):/. 2!$!2   Óä°Ó Óä°nÊ   1// 
 18.22 Target trajectory on a passing course. (From A. S. 
 K. Barton, Modern Radar System Analysis , Norwood, Mass: Artech House, 1988, p. 388. 
 Paraboloidal Reflector Antennas. The theory and design of paraboloidal reflector antennas are extensively discussed in the literature.2"4-14'15 The basic geometry is that of Fig. 6Aa, which assumes a parabolic conducting reflector surface of focal length / with a feed at the focus F. 
 The design was built around the sine-cosine synchronization method ofSec. 17”9 and the 300-M c/sec amplitude-modulated r-fequipment of Sec. 1712. 
 53, pp. 116–128,  February 1965. 78. 
 DARDS 4HEIR  KG MASS TOTAL DRY MASS OF THE SPACECRAFT AND THE RADAR  IS LESS THAN THE MASS OF 2!$!23!4 
 :G0.6 L .~0.4- ~0.2 n: 0 0 l1T221T231T24/12SIr.2 Frequency (b) 1.0- '"<I> - 60.8- a :G06 L ~0.4 ~0.2 n: l1r2l/Tj 21T,2/Tj31r2 2 Frequency (C) Figure4.16(a)Frequency-response ofasingle-delay-line canceler forfp=liT.;(b)sameforfp=IITz; (c)compm;ite response withTdTz=t. repetition fr~quencies areintheratioof5 :4.Notethatthefirstblindspeedofthecomposite response isincreased severaltimesoverwhatitwouldbeforaradaroperating ononlyasingle pulserepetition frequency. Zeroresponse occursonlywhentheblindspeedsofeachprf coincide. 
 The local oscillator isa723A/B klystron. Itsupplies r-fpower to both the AFC mixer and the signal mixer. Itsfrequency can bevaried over awide range bymechanical tuning and over asmaller range by varying the reflector voltage. 
 1968. 12.Moore. R.L.:PassiveECMApplied toFalseTargetElimination. 
    $AY (n 
 Image fusion results of proposed method. Figure 16shows the image fusion results of Range–Doppler algorithm. Different from the proposed method, the result of angle 2 has a deformation, and the image registration needs to be performed after the image is corrected. 
 During reception the antenna collects the energy contained in the reflected target echo signals and delivers it to the receiver. Thus the radar antenna is used to fulfill reciprocal but related roles during its transmit and receive modes. In both of these modes or roles, its primary purpose is to accurately determine the angular direction of the target. 
 However, it is better to delay the association process slightly so that all detections in  a local neighborhood are received and stored and an association table, such as Table 7.6,  generated. (This has implications about how sectors are scanned with a phased array.) Nearest-neighbor assignment can now be applied to the association table by finding  the smallest statistical distance between a detection and a track, making that associa - tion, and eliminating that detection and track (row and column) from the table. This  process is repeated until there are either no tracks or no detections left. 
 CM DOPPLER RADAR v  * !TMOS /CEANIC 4ECHNOL   VOL     PP n    $ 3 :RNIC  h7EATHER RADAR POLARIMETRY 4RENDS TOWARD OPERATIONAL APPLICATIONS v  "ULL !MER  -ETEOROL 3OC  VOL   PP n    6 . "RINGI AND ! (ENDRY  h4ECHNOLOGY OF POLARIZATION DIVERSITY RADARS FOR METEOROLOGY v   #HAP  IN 2ADAR IN -ETEOROLOGY  !TLAS ED   "OSTON !-3    PP n  6 . "RINGI  4 ! 3ELIGA  AND + !YDIN  h(AIL DETECTION WITH A DIFFERENTIAL REFLECTIVITY RADAR v  3CIENCE  VOL   PP n    * 6IVEKANANDAN  $ 3 :RNIC  3 - %LLIS  2 /YE  ! 6 2YZHKOV  AND * 3TRAKA  h#LOUD MICRO 
 5.Torrey,H.C,andCA.Whitmer: "Crystal Rectifiers," MITRadiation Laboratory Series,vol.15, McGraw-Hili BookCompany, NewYork,1948. 6.Palamutcuoglu, 0.,J.G.Gardiner, andD.P.Howson: Image-Cancelling Mixersat2GHz,Electronic Letters,vol.10,no.7,pp.104-106, Apr.4,1974. 7.Taylor,J.W.,Jr.,andJ.Mattern: Receivers, chap.5of"Radar Handbook," M.I.Skolnik (ed.), McGraw-Hill BookCompany, NewYork,1970. 
 ~0.8 ~0- E4 0.4 Frequency Figure4.12Amplitude responses forthreeMTIdelay-line cancelers. (1)Classical three-pulse canceler, (2)five-pulse delay-line cancelerwith"optimum" weights,and(3)IS-pulseChebyshev design.(AflerHouts andBurlage.26) Wj=weightattheithtap.)Alargenumber ofdelaylinesareseentoberequired ofa nonrecursive canceler ifhighly-shaped filterresponses aredesired.Ithasbeensuggested,26 however, thatevenwithonlyafive,.pulse c'anceler, afive-pulse Chebyshev designprovides significantly widerbandwidth'tha'n the'five-pulse" optimum" design.Toachievethewider bandtheChebyshev designhas"alowerimprovement factor(sinceitisnot"optimum "),butin manycasesthetradeisworthwhile especially iftheclutterspectrum isnarrow.However, when onlyafewpulsesareavailablefo'i'processing ~hereisprobably littlethatcanbedoneto controltheshapeofthefilterCluiracteristic. Thus,thereis~otmuchtobegainedintryingto shapethenonrecursive filterresponse fOfthree-orfour-pulse cancelers otherthantousethe classical sin2orsin3response' ofthe,"optimum ·'canceler. 
 12.24  Scattering Coefficient from Images  ....................  12.28  Bistatic Measurements  .......................................  12.28  12.6 General Models for Scattering Coefficient  (Clutter Models)  ...................................................... 
 V , pp. 3539–3542, 2004. 146. 
 Microrraoe J., vol. 5. pp. 
 The RCS of the wire varies with the wire length, the angle subtended by the wire and the line of sight, and on that component of the incident electric field in the plane containing the wire and the line of sight. The wire diameter has only a minor influence if it is much smaller than the wavelength. In addition to the prominent broadside lobe at the center of the pattern, there are traveling- wave lobes near the left and right sides. 
 QUENCY INTERVAL IS  .  
 Thephasesof everyotherslottherefore mustbereversed tocausetheradiated energytobeinphase.Thisis accomplished inaslottedwaveguide byaltering thedirection oftiltsofadjacent elements. Ina dipolearray,thephaseisreversed byreversing everyotherdipole. Open-ended waveguides areanother popular formofarrayradiator. 
 Greenwood: A Within-Pulse Scanning Height-Finder, International Co11(er­ e11ce rm Radar-- Prese11r a11d F11t11re, IEE Conference Publication, no. 105, pp. 50-55, 1973. 
 Also, it was observed that such display systems could  accomplish more than one function and not just be used for showing radar on a chart.  This anticipated the concept of multifunction displays, now in use on some integrated  bridge systems. It is interesting to note that Kelvin Hughes and Decca obtained the first type  approval for commercial marine radar in 1948; effectively, both are still supplying  ch22.indd   32 12/17/07   3:02:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 RANGE LOCATIONS ACCORD 
 ITED POWER LEVELS 4HIS CONSTRAINS ACHIEVABLE DATA TRANSFER RATES  REGARDLESS OF CHANNEL  BANDWIDTH !N ASSOCIATED PROBLEM IS VULNERABILITY TO INTERCEPT AND JAMMING INHERENT IN WIDEBEAM APERTURES !N 8 OR +U BAND -&!2 CAN EMIT POWER LEVELS IN THE MULTI 
 Z.Z., Y.L., and L.L. developed the computer simulations and performed the real airborne data analysis. Z.Z., Y.L., and T.Z. 
 Higher power can be obtained by  combining the outputs of a large number of individual devices. Unfortunately. for many radar  applications hundreds or thousands of devices would have to be employed in order to achieve  the requisite power levels. 
 Ó°Ó{  2!$!2 (!.$"//+  4HESE RELATIONSHIPS ARE SHOWN GRAPHICALLY IN &IGURE  4HIS DERIVATION ASSUMES A  LINEAR SYSTEM 4HAT IS  IT IS ASSUMED THAT THE VOLTAGE ENVELOPE OF THE ECHO SIGNALS  AS THE  ANTENNA SCANS PAST A POINT TARGET  IS IDENTICAL TO THE TWO 
 Ê /Ê, ,Ê-9-/ 
 BEAM GROUND RETURN POINT " IN &IGURE    WHICH IMPROVES AZIMUTH SIDELOBES AND NARROWS THE SPECTRUM  AS SUGGESTED IN THE CENTER GRAPH SHOWN IN &IGURE  4HE PRESUMMER OUTPUT IS RESAMPLED AT A LOWER RATE   F 3  CONSISTENT WITH  ACCEPTABLE FILTER ALIASING 4HEN  RANGE PULSE COMPRESSION IS PERFORMED  ASSUMING THE TRANSMITTED PULSE IS VERY LONG COMPARED TO THE RANGE SWATH )F CHIRP LINEAR &-  IS USED  PART OF THE hSTRETCHv PULSE COMPRESSION PROCESSING IS PERFORMED IN THE RANGE COMPRES 
 FT ANTENNA MAST COMPARED WITH APPROXIMATELY  NMI FOR A   
 10”42. The development ofsuch tubes forstill higher power levels isunder way. Anonlinear inductance can also beused asaswitch. 
 PLE  A LINEAR &- CHIRP WAVEFORM REQUIRES A PHASE THAT CHANGES IN A SQUARE 
 Scan rates of practical search radars vary from 1 to 60 rpm, 5 or  6 rpm heing typical for the long-range surveillance of aircraft.  The coverage of a simple fan beam is usually inadequate for targets at high altitudes close  to the radar. Tltc simple fan-beam antenna radiates very little of its energy in this direction. 
 This gives ana-coutput error voltage that can bereadily amplified, but has the disadvantage ofarelatively long time constant. The thermistor bridge, though rather difficult tocom- pensate forwide variations intemperature, regulates totherms value of theoutput wave, which isaconsiderable advantage forsome applications. The third form ofvoltage-sensitive element was atungsten-filament diode operated inthe region ofsaturated emission. 
 TION AND THE FREQUENCY OPTIONS SELECTED BY THE OPERATOR 4HE ANTENNAARRAY SHOWN IN &IGURE  IS CONSTRUCTED OF EITHER  !.403 
 ORDER NONLINEAR WAVE 
 W.: Radar Waveform Selection-A Simplified Approach, IEEE Trans., vol. AES-7, pp.  1078-1086, November, 1971. 
 For IF frequencies below (H - L)IH = 0.14 the spurious frequencies originate from extremely high-order terms in the power-series model and are con- sequently so low in amplitude that they can usually be ignored. For this reason, single-conversion receivers generally provide better suppression of spurious re- sponses than double-conversion receivers. The rationale for a choice of double conversion should always be validated. 
 36.)  41 Dyer. F. B .. 
 The Stable Local Oscillator.-Two types of10-cm local oscillator tubes have been investigated: the type 417 and type 2K28 reflex klystrons. The 417 has abuilt-in cavity and istherefore more microphonics than the2K28, which hasaremountable cavity. However, theexternal cavity gives the 2K28 alower Q,which causes larger noise fluctuations and greater sensitivity toexternal 60-cps magnetic fields. 
   PP n  -ARCH   % 0 3CHELONKA  h!DAPTIVE CONTROL TECHNIQUE FOR ON 
 It is beyond the scope of this chapter to address this topic in detail. However, it’s useful  to show a couple examples for illustration. Consider, first, a ground-based dual-reflector design with a 9-meter main reflector  aperture. 
 The net  result is that evanescent waves are excited in air, whereas in the dielectric the energy  is concentrated and preferentially induced by a factor of n3:1. The respective calculated far-field power density patterns, in both air and dielectric,  are given by Rutledge29 (see Table 21.4), and these are plotted for a relative dielectric  constant of 9 in Figure 21.19 and Figure 21.20. For comparison, the far-field pattern  of a dipole radiating into free space is shown in Figure 21.21. 
 84.OdIum, W.J.:Selection ofaPhasedArrayAntenna forRadarApplications, IEEETrailS,vol.AES-3. no.6(SupplemerH), pp.226-235, November, 1967. 85.Blass,J.:Multidirectional Antenna-A NewApproach toStacked Beams,1960IREItIlematiOll£l1 COllrellfioll Record, pI.I,pp.48-50. 
 Unfortunately, for a specific radar this might not be feasible. If there is uncertainty about whether or not the noise is Rayleigh-distributed, it is  better to threshold individual pulses and use a binary integrator as shown in Figure 7.13.  This detector is tolerant of variations in the noise density because by setting K to yield  a 1 with probability 0.1, a Pfa ≈ 10−6 can be obtained by using a 7-out-of-9 detector. 
 Preferred Grouping ojCom- ponents.—Considerations ofaccessibility and convenience would often argue forputting most ofthecomponents ofaradar setnear theindicator rather than near the antenna, which, inorder toget the proper view, must usually beataremote orisolated point. However, the long-line eflect discussed inSec. 11”1 makes along transmission line from magne- tron toantenna something tobeavoided ifpossible. 
 DOMAIN DIGITAL  PULSE COMPRESSION PROCESSOR #!      !              !       #!       
 SIGHT VELOCITY OF POINT !  IS TOWARD THE RADAR  WHEREAS THE APPARENT LINE 
 FLY THE ILLUMINATION  AND LOW 
 This is needed to capture the doppler filter containing the target, through the radar’s AGC  action. The repeater jammer signal is then further shifted in frequency to the maximum  expected doppler frequency of the radar. The repeated signal is then switched off, forcing  the victim radar to reacquire the target.3 Coherent tracking radars can check the radial  velocity derived from doppler measurements with that derived from differentiated range  data. 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°Ç WHERE   A   BEAMWIDTH     AND ! AND ! ARE THE TWO LARGEST AMPLITUDES OF THE RETURNED SAMPLES AND OCCUR AT  ANGLES P AND P   P   $P  RESPECTIVELY "ECAUSE THE ESTIMATE SHOULD LIE BETWEEN  P  AND P AND %Q  WILL NOT ALWAYS YIELD SUCH AN ESTIMATE  }Q SHOULD BE SET EQUAL TO  P  IF}Q  P AND }Q SHOULD BE EQUAL TO  P IF }Q   P 4HE ACCURACY OF THIS ESTIMATOR IS GIVEN  IN &IGURE  FOR THE CASE OF  N    PULSES PER BEAMWIDTH 4HIS ESTIMATION PROCEDURE  CAN ALSO BE USED TO ESTIMATE THE ELEVATION ANGLE OF A TARGET IN MULTIBEAM SYSTEMS WHERE  P AND P ARE THE ELEVATION 
 Full array instantaneous bandwidth requires equal path lengths between  each array element and the target, requiring many wavelengths of phase control or the  equivalent time delay in array elements at wide angle scans. However, this control has  prohibitively high loss for typical phased array radiating elements; consequently, typi - cal phased array elements provide only sufficient phase control of up to 360° or to one  wavelength, limited to tolerable loss, to cause the signal from each element to arrive  approximately in phase at the target. Unfortunately, this shortcut is adequate for only  a narrow instantaneous bandwidth. 
 BAND INTERFERENCE   &)'52%  ,OW 
 Ringel, M. B.: Detection Range Analysis of an Airborne Medium PRF Radar, IEEE NAECON Rec., Dayton, Ohio, pp. 358-362, 1981. 
 Although it tends to collect on many types of structures and can obtain large  thickriesses. both theory and experinlent show a lack of rime-ice formation on a spherical  radome.' ' "The trajectories of water droplets in the air stream flowing around large spheres do  not result in much impingement. Collection efficiencies might be only a few percent. 
   4HAT , 
 NOISE SPECTRAL DENSITY IS SHOWN IN &IGURE  4HE TOTAL NOISE  POWER WITH RESPECT TO THE CARRIER IS DETERMINED BY INTEGRATION OF THE NOISE POWER UNDER  THE CURVE 4HE EQUATION FOR THE POWER SPECTRAL DENSITY OF ANY ONE SEGMENT AS A FUNC 
 SCAN COMPENSATION USUALLY REQUIRES THE DIFFERENCE 
 At the other extreme from the Rayleigh region is the optical region, where the dimensions  of the sphere are large compared with the wavelength (2na/l ~ 1). For large 2rca/l, the radar  cross section approaches the optical cross section na2• In between the optical and the Rayleigh  region is the Mie, or resonance, region. The cross section is oscillatory with frequency within  this region. 
 ;\change inphasecanbeobtained byutilizing oneofa number oflengthsoftransmission linetoapproximate thedesiredvalueofphase.Thevarious lengthsoflineareinserted andrellloved byhigh-speed electronic switching. Semiconductor diodesandferritesarcthedevicescomlllonly employed indigitalphaseshifters. Thereareatleasttwomethods forswitching lengthsoftransmission lines.Inone,the properlinelengthisselected fromamongmanyavailable lengths. 
 RECEIVERS, DISPLAYS, AND DUPLEXERS 349  recovered by subtracting the outputs of the two diode mixers. In Fig. 9.2 the balanced diodes  are shown reversed so that the IF outputs can be added. 
 IGARSS 85 ,  pp. 454–457, 1985. 32. 
 the computer will attempt to correlate them with existing tracks and initiate new tracks, which  can tie up the computer capacity needlessly. Multiple detections of the same target can occur  in adjacent beam positions if the echo signal is of more than marginal strength. If the beam  scans a uniform pattern, as it would if it were generated by a conventional mechanically  scanned antenna, extraneous hits from adjacent beam positions can be readily recognized as  such. 
 588 152 The Need forSystem Testing. 590 DESIGN OF AHIGH-PERFOEXANCE RAnAR FOB Am SURVEILLANCE AND CONTROL, ...... ... 
 It is usually easier  to design a depressed collector for a TWT than for a klystron since the spent electron  beam of a TWT might have a 20% spread in velocity, but the klystron might have a  velocity spread of almost 100%.17 Because the efficiency in a conventional TWT is  usually lower than that of a klystron, the increase in efficiency in the TWT provided  by a depressed collector has a greater relative effect than with a klystron. ch10.indd   10 12/17/07   2:19:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Calling the width at the base of the triangle r8 = 2T2, the rms error is  oT. _ ta  R -ju(2E/N0)112 triangular pulse ( I J.23)  Consider a pulse described by the gaussian function  ( l.384t2 ) s(t) = exp -t2 (11.24) . EXIRACIION OF lNl'ORM/\TlON i\NlJ WAVEFORM DESIGN 407 . 
 OF 
 The dashed straight line applies to an integration-improvement factor proportional to  n112• As discussed in Sec. 10.6, data obtained during World War II seemed to indicate that this  described the performance of an operator viewing a cathode-ray tube display. More recent  experiments, however, show that the operator-integration performance when viewing a  properly designed PPI or B-scope display is better represented by the theoretical postdetec­ tion integrator as given by Fig. 
 DICTED 3.2KI   AND FINALLY SELECTING THE WAVEFORM INDEX  I SUCH THAT THE CORRESPONDING  3.2KI  IS JUST GREATER THAN THE DESIRED DETECTION THRESHOLD PLUS A GIVEN TOLERANCE %##- ! 
 88–94. 27. L. 
   PP n    ' * 0ORTMANN  * -OORE  AND 7 ' "ATH  h3EPARATED COVARIANCE FILTERING v IN  2EC )%%%   )NTERNATIONAL 2ADAR #ONFERENCE    PP n  0 -OOKERJEE AND &  2EIFLER  h2EDUCED STATE  ESTIMATOR FOR SYSTEMS WITH PARAMETRIC INPUTS v )%%%  4RANS !EROSPACE AND %LECTRONIC 3YSTEMS  VOL   NO   PP n    ! 3 'ELB  !PPLIED /PTIMAL %STIMATION  #AMBRIDGE  -! -)4 0RESS    & 2 #ASTELLA  h-ULTISENSOR  MULTISITE TRACKING FILTER v  )%% 0ROC 2ADAR  3ONAR .AVIGATION    VOL   ISSUE   PP n    % ! 7AN  2 VAN DER -ERWE  AND ! 4 .ELSON  h$UAL ESTIMATION AND THE UNSCENTED TRANSFORMA 
 Therearetwoclutterreduction techniques, peculiar tolandclutter,whichwillbemen­ tionedbrieflyinthissection. ThesearetheclutterfenceandtheKalmus clutterfilter. Kalmus clutterfilter.59Thisisatechnique forextracting moving targets,suchasawalking personoraslowlymovingvehicle,fromlandclutterwhosedoppler-frequency spectrum masks thatofthemoving target.Amovingtargetwillproduce adoppler-frequency shiftthatiseither atalowerorahigherfrequency thanthetransmitted signal.Vegetation ortreeswillhavea back-and-forth motionduetothewind;hence,thedoppler spectrum fromsuchclutterwillbe distributed onbothsidesofthetransmitted frequency, especially ifobserved overasufficielit periodoftirpe.Bysplitting thereceived spectrum intotwohalvesaboutthetransmitted carrier andsubtracting thelowerpartfromtheupperpart,thesymmetrical clutterspectrum will cancelandtheasymmetrical targetspectrum willnot.Thismethodofsuppressing theclutter relativetothetargethasbeencalledtheKalmusclutterfilter.Theseparation ofthereceding doppler signalsfromtheapproaching doppler signalsmaybeaccomplished withatechnique similartothatshowninFig.3.8.Quantitative measurements ofthetarget-to-clutter enhance­ mentofthistechnique arenotknown,butithasbeensaid59that"smalltargetsmovinginone direction couldbeeasilydetected inthepresence ofcluttersignalsexceeding thetargetreturn bymanyordersofmagnitude." Theeffectiveness ofthistechnique islimitedbythedegreeof symmetry oftheclutterspectrum, theneedforasufficient averaging time,andbytheassump­ tionthattheclutterfluctuations arelargecompared tootherfactorsthatmightaffectthe symmetry ofthereceiver spectrum. 
 With a complex target such as an aircraft the reflected energy is more or  less equally divided between the two senses of rotation so that some target-echo energy is  accepted by the same radar antenna that transmitted the circularly polarized signal. This is the  basis for target-to-clutter enhancement using circular polarization.  A circularly polarized wave is one in which the electric field vector rotates with constant  amplitude about the axis of propagation at the radar frequency. 
 For instance, the high sidelobes that accompany a uniform illt~mina-  tion are seldom desired, and the aperture efficiency is usually willingly sacrificed for lower  sidelobes. When a shaped beam is desired in a surveillance radar, such as a cosecant-squared  pattern, again it is more important to achieve the overall pattern required rather than simply  nlax'imize the directivity at the peak of the beam.  Aperture efficiency is a measure of the radiation intensity only at the center of the beam. 
 ING IS DECREASED %VAPORATION $UCTS  ! CHANGE IN THE MOISTURE DISTRIBUTION WITHOUT AN ACCOM 
 The third coordinate usually appears inaseparate presentation onanother tube, often asaprojection of alltargets onavertical plane. Intensity-modulated displays ofplane surfaces constitute themost important class ofradar indicators. ThePlan-position Indicator.—If the slant range and azimuth coordi- nates ofthe various targets inthefield ofview arerepresented, respec- tively, bydistance from the center ofaCRT and byazimuth onthe tube face, theresult isamap. 
   .!3!  %ARTH 3CIENCE )NSTRUMENT )NCUBATOR 0ROGRAM  *0,  #ALIF )NST 4ECH  0ASADENA  #!    2 -ENEGHINI AND $ !TLAS  h3IMULTANEOUS OCEAN CROSS 
 14 Range resolution applied to scatterometry: ( a) improving one dimension of a   circular-beam illumination pattern and ( b) use with a fan beam ch16.indd   22 12/19/07   4:55:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 For large values ofxitislogarithmic. A receiver with this characteristic iscalled alin-log receiver. The output ofthelin-log i-famplifier has tobeadded tothereference signal and then detected. 
 89-90, Feb. 22, 1973.  37. 
 S. Kim et al .126) FIGURE   16. 45 Polarimetric ellipse: c is  the ellipticity angle, and y  is the orientation  angle. 
 SEC.17.6] THEPHASE-SHIFT METHOD 695 toitsdelay time. Ifthe modulator isself-synchronous, itsfiring time must coincide with thefirst coded pulse. Arangeerror intheindicators results unless acompensating delay line isused inthevideo channel atone station ortheother. 
 13- 14, January, 1973.  9. Shigemoto, J.: Balanced Mixer Noise Considerations, Microwaoe J., vol. 
 ANGLE SEA CLUTTER SEE 7ETZEL  FOR A DETAILED DISCUSSION   THERE IS EVI 
 LEVEL RESOLUTION /NE CAN THEN THINK OF IMAGE RESOLUTION  IN TERMS OF A VOLUME   6   RARYRG    . 
 Even if the RF amplifier itself has more than adequate  dynamic range, the mixer dynamic range has been compromised, as indicated below: Example 1 Example 2 Example 3 Ratio of front-end noise to mixer noise 6 dB 10.0 dB 13.3 dB Sacrifice in mixer dynamic range 7 dB 10.4 dB 13.5 dB Degradation of system noise temperature due  to mixer noise1 dB  0.4 dB  0.2 dB The same considerations apply to the setting of the noise level at the input to the  A/D converters. Traditionally, the noise contribution of the A/D converter was con - sidered by the system engineers as a separate contribution to the overall radar system  noise, distinct from receiver noise, and was accounted for at the system level. Today, it  has become common to include the A/D converter noise as part of the overall receiver  noise. 
     
   PP n  -AY   2 3 3YMONS AND * 2 - 6AUGHAN  h4HE LINEAR THEORY OF THE CLUSTERED CAVITY KLYSTRON v  )%%%  4RANS  VOL 03 
 SELECTION ENABLED 2!$!23!4 
 J. H.. and D. 
 The first uses a single overhead  support point and guy lines to a floor-mounted turntable to rotate the target. The sec - ond configuration suspends the target from an overhead turntable, reducing the guy  lines and string loads at the expense of a more costly installation. The third configura - tion is the most costly, using a pair of turntables slaved together, one in the ceiling and  one on the floor. 
 In terrain avoidance (TA), the antenna scan is in a horizontal plane (shown in the  upper left of Figure 5.25). Several altitude plane cuts are estimated and presented to  FIGURE 5.25  TF/TA mode example ( adapted8; courtesy SciTech Publishing ) ch05.indd   28 12/17/07   1:27:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 SISTENT DATA RATE DURING PERIODS OF REDUCED PROBABILITY OF DETECTION &IGURE  ILLUSTRATES THE SENSITIVITY TO TARGET FADES BY PLOTTING THE TRACK REGION OF UNCERTAINTY 2/5  VERSUS THE PROBABILITY OF DETECTION FOR SINGLE RADAR TRACKING AND MULTIPLE RADAR TRACKING 4HE 2/5 IS DEFINED AS THE DISTANCE THAT CONTAINS THE ERROR WITH  PERCENT PROBABILITY AND IS 2/5   TRACKING ERROR DUE TO DETECTION NOISE    TRACKING ERROR DUE TO MANEUVER  4HIS CAN BE CALCULATED FOR ANY CASE OF INTEREST USING THE FORMULAS IN 4ABLE  &)'52%  4HERE ARE TWO COMMON METHODS OF FUSION DATA IN RADAR NETWORKING DETECTION 
  PROBE  SCATTERED OFF THE MOONS SURFACE  AND  THEN RECEIVED BY AN %ARTH 
 TO 
 The amplitude-comparison monopulse employs two  overlapping antenna patterns (Fig. 5.7a) to obtain the angular error in one coordinate. The  two overlapping antenna beams may be generated with a single reflector or with a lens  antenna illuminated by two adjacent feeds. 
 26, pp. 93–105, July 1983. 54. 
 Figure 2.16shows the installation in the rear of a Sunderland of ARI 5205, the high- power transmitter, T.3140, and the separate modulator, type 52. Figure 2.14. Installations of ASV Mk. 
  AT TIME TK PROVIDING THE NEW ESTIMATES  8K\K AND 0K\K AND  THE VALUES  RK \K  BK \K AND EK \K AT THE NEXT TIME INSTANT  TK  4HE SCHEDULER PROVIDES THE  WAVEFORM TO RADIATE 7K  AND THE THRESHOLD AK  TO APPLY FOR TARGET DETECTION AT TK  3ELECTION OF THE 3AMPLING 0ERIOD  4HE SAMPLING PERIOD IS CHOSEN AMONG A FINITE  NUMBER OF POSSIBLE DIFFERENT VALUES BASED ON KINEMATIC CONSIDERATIONS ON THE TARGET  ESTIMATED SPEED  AS WELL AS ON WHETHER MISSED DETECTIONS HAVE OCCURRED )F THERE  IS NO MEASUREMENT TO BE ASSOCIATED TO THE TARGET  THE SAMPLING PERIOD IS SET EQUAL TO    4S    S AND THE WAVEFORM OF HIGHEST ENERGY IS SELECTED  SO AS TO POSSIBLY AVOID A  SECOND MISSED DETECTION DUE TO THE POSSIBLY LOW TARGET 
 Legislation and an ETSI product specification means  that this equipment will need to conform to the Radio & Telecommunications  Terminal Equipment (R&TTE) — Directive. In the short term, until a new prod - uct specification is introduced and formally published in the Official Journal of  the European Communities, the EMC Directive should be applied. All equip - ment, including ultrawideband radar or GPR, must be ( Conformité Européene)  CE marked to demonstrate that it satisfies the relevant directives of the European  Union. 
 used tile filter is called rectrrsive. Using the Z-trarisform as the basis for design it is possible in  principle to synthesize almost any frequency-response f~nction.~~"-'~  Ttie canoriical configuration is useful for conceptual purposes, but it may not always be  desirable to design a filter in this manner. White and Ruvin2 state that the canonical  configuration may be broken into cascaded sections, no section having more than two delay  elements. 
 The total transmit power is combined only in space, in the far-field collimated beam. The planar array antenna consists of 54 rows of horizontal stripline linear arrays. Each of the 54 rows contains its own solid-state modular transceiver consisting of a 1-kW nominal RF peak-power solid-state transmitter, integral power supply, low-noise receiver, phase shifter, duplexer, and logic con- trol, all mounted on the antenna. 
 INDEX 579  Radial velocity direction, in CW radar, 78-79  Radiation hazards, 465-466  Radiation intensity, 224  Radiation pattern:  antenna, 224, 228-235  array, 280-282  Radomes, 264-270  Rain:  and radomes, 269-270  scattering from, 500-502  at millimeter waves, 564  Random errors:  in array antennas, 318-322  in reflector antennas, 262-264  Range accuracy, 401-407  Range ambiguities, 53-54  Range-gate stealer, 551  Range-gated doppler filters, 117-1 19  Range measurement, in CW radar, 95-98  Range resolution, and automatic detection, 186  Range tracking, 176- 177  Raster scan, 178  Rayleigh probability density function, 22-23, 47  and sea echo, 478  Rayleigh region, 33-34  Rayleigh scattering, 499  Rear-port display, 358-359  Receiver noise, 18-19  Receiver protector, 362-363  Receivers, 343-353  Recirculatingdelay-line integrator, 390-392  Recursive filter, 113  Reference gain, MTI, 1 11  Reflectarray, 309  Reflection coefficient, of sea, 445  Reflective-array compressor, 425  Refraction, 447-450, 455-456  ~efractivitf. 448  Refractometer, 455  Reggia-Spencer phase shifter, 291-293  Repeater jamming, 551-552  Resolution, of SAR, 518-519  Resonance region, in scattering, 34  Resonant-charging, modulator, 215  Resonant frequency, of tracking antennas, 179  RF keying, of CFA. 21 1  Rice probability density function, 26, 50  Rieke diagram, magnetron, 195-1 98  Ring-bar TWT, 206  Ring echoes, 512  Ring-loop TWT, 207  Ring tuner, magnetron, 200  Rising-sun magnetron, 193, 194  Rod, radar cross section of, 34-35 Roll stabilization, 27 1  Rotodome, 268  Sample and hold, 156  SAR, 517-529  SAW delay lines, 424-426  SCAMP, 163  Scan with compensation, 164  Scan converter, 358  Scanning-feed reflector antennas, 244-248  Schottky-barrier diodes, 347  Schwartz inequality, 372  Sea clutter, 474-489  HF radar, 533-535  at millimeter waves, 563-564  Sea state, 475  Second-time-around echo, 3  in MTI, 117  Self-screening range, 550  Semiactive homing, 80  Sensitivity time control (see STC)  Sequential detection, 38 1-382  in array radar, 324  Sequential lobing, 153-154  Sequential observer, 380-382  Series-fed array, 285  Servo noise, 170  Servo system, 178-179  Shadow grid, 203  Ships, radar cross section of, 42-45  Short pulse, applications of, 421  Sideband superheterodyne receiver, 84-85  Sidelobe canceler, 333, 549  Sidelobes, antenna, 227-228  Sidelobes, FM pulse compression, 426427  Sidelooking radar, 5 17  Sigma zero, 471  Signal management, in array radar, 324  Signal-to-noise ratio:  for detection, 28, 48  . 
 The received echo signal is fed to the  receiver from the antenna via two rotary joints (not shown in the block diagram). One rotary  joint permits motion in azimuth; the other, in elevation.  rotation  Figure 5.2 Conical-scan tracking. 
 WAVE RADAR 4HIS EXPERIMENTAL 7ARLOC RADAR WAS EMPLOYED TO DEMONSTRATE AT 7 BAND THE )3!2 IMAGING OF MOVING TARGETS  CLOUD STRUCTURE  LOW 
 151. M. Hall (ed.), “Special papers: Multiple parameter radar measurements of precipitation,” Radio  Sci., vol. 
 Nearest-neighbor assignment is the most common solution to this problem. The  simplest form of nearest neighbor works sequentially on incoming data. As each new  detection is made, it is assigned to the track with which it has the smallest statistical  distance. 
 Letussummarize what wedoknow, once weareprovided with theover-all noise figure and bandwidth ofthe receiver, thetransmitted power, and thegeometrical factors intheradar equation which concern theantenna and thetarget. Weknow theratio oftheamplified signal power totheaverage value ofthe amplified noise power. We arenotyet able tosay how large this ratio must bebefore thesignal can beidentified with reasonable certainty. 
 TIPLE DOPPLER FILTERS  SUCH AS THE -4$  EACH DOPPLER FILTER WILL ALSO HAVE A COHER 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 Target angle noise is typically gaussian-distributed. 
 È°{Ó  2!$!2 (!.$"//+  SELECTING EVERY  $TH SAMPLE 0ROVIDED THE FILTER RESPONSE  (V  HAS SUFFICIENT REJECTION  FOR FREQUENCIES \ \  VqP$  THERE WILL BE NEGLIGIBLE ALIASING AND LOSS OF INFORMATION IN  THE DECIMATION PROCESS&)'52%  $IGITAL DOWNCONVERSION ARCHITECTURE                      
 TION EQUIPMENT  SUCH AS !)3  '03  GYROCOMPASS  LOG  AND ECHO SO UNDER  AND IS ALSO  LIKELY TO BE COMMUNICATING TRACK INFORMATION TO ELECTRONIC CHART SYSTEMS AND POSSIBLY OTHER RADAR DISPLAYS ! NUMBER OF MANUFACTURERS PRODUCE RADARS SPECIFICALLY DESIGNED TO BE USED ON  VESSELS USING THE WORLDS MAJOR INLAND WATERWAYS 4HESE ARE KNOWN AS  RIVER RADARS  4HEY ARE EPITOMIZED BY THEIR SUPERIOR SHORT 
 The peak of  the ambiguity function is shifted to t  = fdT/B for a positive LFM slope. Time Delay and Range Resolution Widths.  The time-delay resolution width is equal  to the width of the ambiguity function at a specified level relative to the peak value. 
 A simple block diagram of a radar superheter­ odyne receiver was shown in Fig. 1.2. There are many factors that enter into the design of  radar receivers; however, only the receiver noise-figure and the receiver front-end, as thc;y  determine receiver sensitivity, will be discussed here. 
 Chapters 16and 17take uptwo new and important ancillary ix. x PREFACE techniques that arenot dealt with fully elsewhere intheSeries: moving- target indication and the transmission ofradar displays toaremote indicator byradio means. For fuller information than can befound inthis book onany detailed point ofdesign, the reader isreferred toone ofthe other books ofthe Series. 
 Anentirely arbitrary criterion, \rhich will serve aswell asany other fordiscussion, istherange for\vhich thepresence oftheatmospheric attenuation just doubles thenormal rate ofdecrease ofsignal intensity with range. Ifaistherate ofattenuation indb/km, the range ROsodefined isgiven byRo=8.68/a km. At shorter ranges than this the inverse-square la~v isthe more important factor; atranges greater than R,the exponential factor controls the situation and any slight improvement inrange must bebought atenor- mous price. 
 MENTED EITHER AS A DIGITAL PHASE SHIFT OR DIGITAL TIME DELAY  FOLLOWED BY A DIGITAL SUMMER 4HIS CONFIGURATION ALLOWS BEAMS TO BE FORMED IN ANY DIRECTION  AND MULTIPLE BEAMS CAN BE FORMED SIMULTANEOUSLY  IF DESIRED  BY USING THE SAME SAMPLE DATA AND IMPLEMENTING DIFFERENT TIME DELAYS TO FORM THE DIFFERENT BEAMS (OWEVER  AT THIS WRITING  PUTTING A DIGITAL RECEIVER BEHIND EVERY ELEMENT IS EXPENSIVE AND IS USUALLY NOT FEASIBLE FOR MOST LARGE ANTENNA APPLICATIONS IE  FOR SYSTEMS WITH THOUSANDS OF ELEMENTS  /NE COMPRO 
 Thus, they are insusceptible to spatial-temporal decorrelation [ 22]. Deformation modeling is a crucial step in time-series processing, determining the temporal and functional relationships between the phase component of displacement and the deformation parameters over highly coherent points. An accurate and reliable deformation model can not only improve the accuracy of deformation estimation, but also control the residual phase within a reasonable range of a whole phase cycle [ −π,π]. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 Equation 24.1 is the basis of performance calculation for an RWR. 
 The reflected power   causes antenna mismatch in small radomes and sidelobes in larger radomes. Radome design is a specialized art, and many books53,54 are devoted to its intricate  details. This section makes no attempt to provide radome design information as such  but instead is aimed at making the radar system designer aware of the basic concepts  behind the types of radomes available for various applications. 
 Colegrove and S. J. Davey,  “PDAF with multiple clutter regions and target models,” IEEE  Trans. 
 The display was a vertical trace, with echoes shown as sideways de ﬂections, or blips, to the right (similar to the displays in ASV Mk. I and Mk. II). 
 #OMPARISON -ONOPULSE  ! METHOD FOR VISUALIZING THE OPERATION OF  AN AMPLITUDE 
 The finite beamwidth limits the  resolution available at longer ranges. At shorter ranges, the large solid angle that must  be scanned in order to cover all regions of a storm requires total scanning times of the  order of 3 to 5 min even for well-situated storms. This is a consequence of the on-target  dwell time necessary for accurate measurements. 
 H. Stevens: Pulse Compression, chap. 20 of" Radar Handbook,"  M. 
     
 As new requirements have been generated in response to more severe threats, new approaches using new technology have been developed. This sec- tion will attempt to trace some of these evolutionary developments. Basic Semiactive Seeker.2'6'7 The block diagram of Fig. 
 BASED 3!2 SYSTEMS HAVE MOTIVATED FRUITFUL SPECIALIZATIONS IN QUANTITATIVE  APPLICATIONS IN A WIDE VARIETY OF AREAS  COMPREHENSIVELY REVIEWED IN THE  0RINCIPLES  AND !PPLICATIONS OF )MAGING 2ADAR   4OPICS SUCH AS 3POT3!2  3CAN3!2  POLARIMETRY   AND INTERFEROMETRY THAT HAVE INFLUENCED RADAR SYSTEM AND MISSION DESIGN ARE OUTLINED IN CLOSING PARAGRAPHS OF THIS SECTION &LIGHT 3YSTEMS  4HE CONCEPT OF 3!2  INTRODUCED IN  BY #ARL 7ILEY   WAS  REDUCED TO PRACTICE IN SUBSEQUENT YEARS  FIRST THROUGH SIMULATIONS  THEN THROUGH AIR 
 W. Tolbert: Anomalies in the Absorption of Radio Waves by Atmospheric  Gases, Proc. IRE, vol. 
 (See Section 18.4 for fur - ther discussion.) (4)  Full or quadrature polarization  This is the richest option because it allows full  characterization of the complex matrix of the backscatter at all resolved points in  the scene. It has been developed extensively in theory and in practice with data  from airborne systems and SIR-C. Japan’s PALSAR is the first operational space- based system to incorporate a quad-pol mode. 
 THE RADAR TRANSMITTER  10.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 that of the klystron, and they both use the process of velocity modulation to cause the  electron beam to be periodically bunched (density modulation). The electron beam  passes through the RF interaction circuit. In the example shown in Figure 10.2, where  a helix is shown as the slow-wave structure, the RF signal is slowed down by the  helix so that its forward velocity is very nearly equal to that of the velocity of the  electron beam. 
 The performance ofCH stations was controlled bythe reflections from theground ofboth thetransmitted and thereceived signals. The antenna patterns ofthe transmitting and receiving arrays were not identical and there were large gaps inthevertical coverage ofthestations. Inorder tominimize the importance ofthe gaps, separate auxiliary ‘‘gap-filling” transmitting and receiving arrays were installed toallow aircraft tobefollowed through the gaps produced bythe main arrays (see Figs. 
 1973.  12. Pittack, U .. 
   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°ÎÎ &OR A   
 75. H. O. 
 Sensors 2019 ,19, 743 (i) SBAS-InSAR method with Radarsat-2 data could be used for longtime monitoring of land subsidence with acceptable accuracy in Wuhan city; (ii) natural conditions provide a basis for subsidence and make subsidence possible while human activities are driving factors and make subsidence happen. Despite our success of longtime monitoring of subsidence in a megacity, Wuhan city, other advanced InSAR methods could also be investigated, such as PS-InSAR. Future study will be focused on the causes of subsidence and its spatial differences using spatial regression models. 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing.  RADAR DIGITAL SIGNAL PROCESSING  25.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 line (a) LO signals, are then as in line (c). Because our hypothetical IF signal on  line (b) was exactly at one quarter of the sample rate, both I and Q are constants, the  sine and cosine of the IF signal’s phase angle. 
 16.3 PLATFORMMOTIONANDALTITUDE EFFECTS ON MTI PERFORMANCE MTI discriminates between airborne moving targets and stationary land or sea clutter. However, in the airborne case the clutter moves with respect to the air- borne platform. It is possible to compensate for the mean clutter radial velocity . 
 In this example, that factor is 102,  or 20 dB. Outdoor Test Ranges.  Outdoor test ranges are required when test targets are too  large to be measured indoors. 
 T. Ulaby, “Vegetation clutter model,” IEEE Trans. , vol. 
 Anderson, M. W. Fox, P. 
 Shrader, W.W.: Moving Target Indication Radar, IEEE NEREM 74 Record. pt 4: Radar Syst.:ms  and Components, Oct. 28-31, 1974, pp. 
 A. Johnson and D. C. 
 N. Bringi and A. Hendry, “Technology of polarization diversity radars for meteorology,”   Chap. 
 TO 
 Its duty cycle is 0.002, with a gain of 33 dB, and a  2 µs pulse width. This TWT was originally designed to be used interchangeably with  the popular V A-87 klystron, except that the V A-125A TWT has a wider bandwidth than  the V A-87 klystron. It also requires a greater power input signal because of its lower  gain than the klystron. 
 I. Knight, and S. Spinella: Electron-Bombarded Semiconductor Devices, "Advances in  Electronics and Electron Physics, vol. 
 Duplexer  To  delay-line  canceler Pulse  modulator  Power  amplifier  Sta lo  Ii.  Coho  {  Reference signal Mix  Figure 4.S Block diagram of MTI radar with  power-amplifier transmitter. 106 INTRODUCTION TO RADAR SYSTEMS  Duplexer  Mix  To  delay-line  canceler Magnetron  oscillator Pulse  modulator  RF locking pulse  Stoia  Coho  CW reference  signal Mix  IF locking  pulse Trigger  generator  Figure 4.6 Block diagram of MTI radar with power-oscillator transmitter. 
 TAGE IS OBTAINED AT THE COST OF A CONSIDERABLE INCREASE IN SIZE AND WEIGHT 4HE NETWORK IN &IGURE  E GIVES SIMPLICITY IN PROGRAMMING BECAUSE EACH PHASE  SHIFTER REQUIRES THE SAME SETTING 4HE INSERTION LOSS INCREASES FOR SUCCESSIVE RADIA 
 P.: Doppler Wave Recognition with High Clutter Rejection, IEEE Trans., vol. AES-3,  no. 6 Suppl., pp. 
 The size of the  correlation interval affects both the magnitude and the directional characteristic of the spuri-  ous radiation that results from the presence of errors.  The first term of Eq. (7.31) represents the no-error radiation pattern reduced by the  factor, exp - p. 
 There is no time separation possible  before the compression. After the compression  the possibility for time separation depends  upon the amplitudes of the target echoes and the side lobes of the compressed function.  . 
 Kampes, H. Runge, and N. Adam, “SRTM and beyond: Current situ - ation and new developments in spaceborne InSAR,” in Proceedings , ISPRS Workshop on High  Resolution Mapping from Space , Hanover, Germany, 2003. 
 The most pop - ular model, the two-scale Bragg model, is actually an assemblage of assumptions  supported by circumstantial evidence; there is still no clear reason why it should  work when it does. In fact, there is increasing evidence from both the tank and the  open ocean that this model fails to account for many aspects of measured sea scatter  behavior. Augmenting it with a term expressing the effect of breaking waves in active  seas has improved predictions, but still perpetuates the ad hoc character of com - posite-surface models. 
 OCJ -rr(d/A)(sln ¢-Sill0(7.24) (7.25) whereEa(1')istheFourier-integral patternwhichapproximates thedesiredpatternE(¢)when A(z)isrestricted toafiniteaperture ofdimension d. Ruze73hasshownthattheapproximation totheantenna patternderivedonthebasisof theFourierintegralforcontinuous antennas (ortheFourier-series methodfordiscretearrays) hastheproperty thatthemean-square deviation between thedesiredandtheapproximate patterns isaminimum. Itisinthissense(leastmeansquare) thattheFourier method is optimum. 
 Ahelixisdepicted astheslow-wave structure inFig.6.11, butTWTsforradarusuallyuseastructure bettersuitedforhighpower.Thevelocity of propagation ofelectromagnetic energyissloweddownbytheperiodic structure sothatitis nearlyequaltothevelocityoftheelectron beam.Itisforthisreasonthathelixandsimilar microwave circuitsarecalledslow-wave structures ordelaylines.Thesynchronism between theelectromagnetic wavepropagating alongtheslow-wave structure andthedocelectron beamresultsinacumulative interaction wpichtransfers energyfromthed-celectron beamto theRFwave,causingtheRFwavetobeamplified. Thesimplehelixwasusedastheslow-wave structure intheearlyTWTsandisstill preferred intraveling-wave tubesatpowerlevelsuptoafewkilowatts. Itiscapableofwider bandwidth thanotherslow-wave structures, butitspowerlimitations donotmakeitsuitable formosthigh-power radarapplications. 
 For  ex.ample, horizontal polarization might be employed with long range air-search radars operat­ ing at VHF or UHF so as to obtain longer range because of the reinforcement of the direct  radiation by the ground-reflected radiation, Sec. 12.2. Circular polarization is often desirable  in radars which must "see" through weather disturbances. 
 LIKE CIRCUIT THAT CONTAINS TWO OR MORE INTERACTION GAPS &IGURE C   3UCH CAVITIES CAN BE USED FOR THE PRIOR CAVITIES  AS WELL AS THE OUTPUT CAVITY 4HIS ALLOWS WIDER BANDWIDTH AND GREATER POWER THAN THE CONVENTIONAL KLYSTRON AMPLIFIER 3TAPRANS ET AL   STATE THAT THE HIGH 
 Atremendous amount ofwork was carried outduring thewar bythe research and engineering staffs ofmany industrial concerns, both large and small. Insome cases, these firms, working either independent y orondevelopment orproduction contracts with thearmed forces orwith NDRC, engineered certain types ofradar sets alltheway through from thebasic idea tothefinished product. Toalarger extent, thecontribu- tion ofindustry was totake the prototype equipment produced in government laboratories and make the design suitable for quantity manuf acture and for service use tinder combat conditions. 
 2.12,  McGraw-Hill Book Company, New York, 1947.  2. Bachynski, M. 
 These signals, forthemost part, aredue toamplitude modulation in the transmitter. This amplitude modulation comes from microphonics and fwm slight variation oftransmitter amplitude with fTE!qU(311Cy.. 146 C-W RADAR SYSTEMS [SEC. 
 The AN/MPN-l equipment, often called GCA (for ground control of approach), istheonly radar designed during the war toprovide accurate. 212 THEGATHERING ANDPRESENTATION OFRADAR DATA [SEC. 615 tracking onaircraft targets bymeans ofrapid scanning. 
  
 AP-12, pp. 479-490, July, 1964 .  .l 1. 
 L. Patterson et al., “Engineer’s Refractive Effects Prediction System (EREPS),” Naval  Command, Control, and Ocean Surveillance Center TD 2648, May 1994.  3. 
  
 For very demanding measurements, such as shown in curve F of Fig. 14.8, it might be well to consult the 1970 edition of this handbook and Ref. 17 of this chapter. 
 Nathanson, Radar Design Principles,  2nd Ed. New York: McGraw-Hill, Inc., 1991,   pp. 449–452. 
 DEVELOPED OPERATION IN THE STABLE  MORE PRE 
 V.: Radar Detection Range Under Atmospheric Ducting Conditions, IEEE 1975-ltiterna­ tional Radar Conference, Arlington, Va., pp. 241-243, lEEE Publication 75 CHO 938-1 AES.  37. 
 C. L. Holloway and R. 
 FACE REFLECTION BY A REAR 
 Many pulses  are being transmitted every second, with sufficient time  interval between them to allow each echo to return from  the greatest distance we have set our radar apparatus up  to measure. The electron beam is also sweeping up and  down the line many times a second, and is being deflected  by a constant succession of returning echoes. All this  happens far too rapidly for the eye to see anything but a  steady, glowing line of light with a couple of blips. 
 4.35 show the improvement in MTI processing that is theo-  retically possible with DPCA and a three-pulse delay-line canceler. (Note that the DPCA  corrects only one canceler of a multiple-stage MTI.63) The curve for x = 0 applies for no  platform motion and represents the maximum improvement offered by an idea platform-  motion cancellation method. It is seen that when the clutter spectral width is small, as for  overland clutter, a significant improvement is offered by DPCA. 
 IEEE, vol. 64, pp. 239-272, February,  1976. 
 ?'lie  design of efficient feed networks. the phase and amplitude control devices, distributed trans-  niitter and/or receiver niodules, and the control algorithms and logic are other probleni areas.  Similar problerns occur with other conformal-array shapes. 
 20.9. With pattern functions of beams A and B assumed to be identical and with the centerlines of beams A and B oriented at elevation angles of 0 - a and 8 + a, respectively, the net received field strength at the feed points of beams A and B (relative to the peak of each beam) is then *The material in this subsection was originally written by Burt Brown and appeared in Sec 22 3 of the first edition of the handbook. ' 'Btom A . 
 chap. 22 of" Radar Handbook." M. I. 
 First Experiment: Datasets Using T raditional CNN model In the ﬁrst experiment, we used the traditional model, as shown in Figure 1a, deal with D1, D2, and D3 datasets. The results of the ﬁrst experiment are summarized in Table 5, where accuracies achieved by the traditional CNN models on our validation data set are listed for the considered three classes of maritime targets. T able 5. 
 246 INTRODUCTION TO RADAR SYSTEMS  resulting secondary beamwidth from the sphere was about l.8° (39.4 dB gain) with a relative  sidelobe level of 20 dB. A total useful scan angle of 140° was demonstrated. This type of  antenna is similar in many respects to the torus antenna described below. 
 150,pp.17-19. 58.Hopkin, V.D.:ColourDisplaysinAirTrafficControl, International Conference onDisplays for Man-Machine Systems, Apr.4-7,1977,lEE(London) Conference Publication no.150,pp.46-49. 59.McLoughlan, S.D.,M.B.Thomas, andG.Watkins: ThePlasmaPanelasaPotential Solution tothe BrightLabelled RadarDisplay Problem, International Conference onDisplays forMan-Machine Systems, Apr.4-7,1977, lEE(London) Conference Publication no.150,pp.14-16. 
 Unfortunately theuseofsuch measures results inanunnatural appearance ofthe display which makes inter- pretation exceedingly difficult. Shorelines, for example, stand out very strongly, asdochanges intheterrain. Similarly asolidly built-up area appears chiefly inoutline, with other strong signals atpoints of changing signal intensity. 
 35. Mutton, J. 0.: Advanced Pulse Compression Techniques, IEEE NAECON '75 Record, pp. 
 TUNED KLYSTRON  TOP  AND CLUSTERED 
 Thetraveling-wave interaction oftheelectron beamandtheRFsignalmaybewitheither aforward traveling-wave (asintheTWT)orwithabackward traveling-wave. Thetypeof interaction isdetermined bytheslow-wave circuitemployed. Aforward-wave interaction takesplacewhenthephasevelocity andthegroupvelocityofthepropagating signalalongthe slow-wave circuitarcinthesamedirection. 
 TEMS CAN BE VALUABLE ON VESSELS ASSISTING WITH CLEAN 
 42”41’N. 143”12’E. would rnakethispossible. 
 P. Clark: Phase Shifters for Arrays, chap. 12 of Radar Halli/hoot.:, M. 
 This picture can be a combination of data from  FIGURE 5.23  A-A ISAR example TA-3B45 ch05.indd   24 12/17/07   1:27:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 
 21.4 Conventional Tech nique  ....................................  21.4 . This page has been reformatted by Knovel to provide easier navigation. 
 Both  rough terrain and high winds tend to· increase atmospheric mixi,ng, consequently reducing the  occurrence of ducting. Radar propagation is normal whenever the upper air is unusually cold  in comparison with·the earth's surface~=! ,,: '  ! ; I 'r . ·~ I t'.Ji J (.. 
 M. Yarnall, “Twenty-seven design aids for antennas, propagation effects and systems planning,”  Microwaves , pp. 47–73, May 1965. 
 AMPLITUDE APPROXIMATION 4HIS CUMBERSOME APPROACH INVOLVES EXTENSIVE COMPUTATIONS EVEN TO OBTAIN LIMITED RESULTS IN INDIVIDUAL CASES  AS SHOWN IN WORK BY (OLLIDAY ET AL  )N ANOTHER LIMITING CASE  THE BASIC INTEGRAL FORMULATION OF THE '"60 IS SOLVED IN  THE OPTICAL APPROXIMATION LARGE  K   RESULTING IN AN EXPRESSION COMMONLY CALLED THE . £x°Îä  2!$!2 (!.$"//+  SPECULAR RETURN  BECAUSE ITS ORIGIN MAY BE TRACED TO PIECES OF THE SURFACE THA T PROVIDE  A REFLECTION POINT FOR THE INCIDENT WAVE  4HIS EXPRESSION IS WRITTEN FOR A GAUSSIAN  SEA SURFACE IN THE FORM   SY Y Y       \ \  CSC EXP; COT  = 
 POWER VERTI 
 108.. SEC. 105] MAGNETRON CHARACTERISTICS 347 Whatever thesource ofthe emission, iftoo large acurrent isdrawn for too long atime, sparking and other instabilities result. 
 Davenport, W. B., Jr., and W. L. 
 lit. C'. \.ol. 
 16. G. D. 
   ¤ ¦¥³ µ´ EXP    B G 3      (ENCE  THE DETECTION THRESHOLD CAN BE SELECTED AT EACH TIME INSTANT   TK  IN THE FOLLOW 
 ENT PROPAGATION OVER BANDWIDTHS GREATER THAN ^ K(Z  EVEN WHEN CLEAR CHANNELS WIDE ENOUGH TO ACCOMMODATE SUCH WAVEFORMS ARE AVAILABLE  WHICH IS INFREQUENTLY -ORE TYPICALLY  CLEAR CHANNELS RANGE FROM n K(Z  SO THE WAVEFORM BANDWIDTH IS NORMALLY CHOSEN TO LIE IN THIS RANGE 4HE CORRESPONDING RANGE RESOLUTIONS EXTEND .   (& /6%2 
 (a)Echopulse;(h)early-late range gates;(c)dilTerence signalbetween earlyandlaterangegates. whichthegatesmustberepositioned byafeedback-control system.Whentheerrorsignalis zero.therangegatesarecentered onthepulse. Therangegatingnecessary toperformautomatic tracking offersseveraladvantages asby­ products. 
 DELAY CANCELER . Ó°În  2!$!2 (!.$"//+  THAN ON THE REAL AXIS OF THE  : 
  
 K.: "Radar System Analysis," originally published by Prentice-Hall in 1964 and republished by Artech House, Norwood, Mass., in 1977. 5. Nathanson, F.: "Radar Signal Processing and the Environment," McGraw-Hill Book Co., New York, 1969. 
 DIATELY UNDER THE  n# ISOTHERM CAN BE SUBSTANTIALLY GREATER THAN IN THE SNOW REGION JUST  ABOVE AND  UNDER SOME CIRCUMSTANCES  GREATER THAN IN THE RAIN BELOW THE MELTING LEVEL &URTHER MELTING CANNOT LEAD TO MUCH FURTHER ENHANCEMENT  APPARENTLY  AND MAY LEAD TO A LESSENING OF THE REFLECTIVITY OF THE  PARTICLE BY BRINGING IT TO SPHERICITY OR BY BREAKING UP  THE PARTICLE -ELTING OF ICE PARTICLES PRODUCES ENHANCED BACKSCATTER  AND THIS EFFECT GIVES RISE TO THE OBSERVED ELEVATED BRIGHT BAND   NEAR THE n# ISOTHERM ,HERMITTE DISCUSSES HAIL ATTENUATION FOR SHORTER WAVELENGTH RADARS WHEN RESONANT  REGION -IE  SCATTERING IS THE DOMINANT SCATTERING MECHANISM 5SING ACCEPTED SIZE  DISTRIBUTIONS OF DRY HAIL  HE SHOWS ATTENUATION RATES OVER THE FREQUENCY INTERVAL OF  n '(Z THAT ARE NEGLIGIBLE AT THE LOWER FREQUENCIES BUT RISE ASYMPTOTICALLY TO ABOUT  D"KM AT FREQUENCIES ABOVE  '(Z !TTENUATION BY &OG  4HE CHARACTERISTIC FEATURE OF A FOG IS THE REDUCTION IN VISIBIL 
 5(;6 INTRODUCTION TO RADAR SYSTEMS  If the target is much larger than the laser beam, as can happen in some situations, 1he radar  equation becomes  R2 _ rcP, A,:11p c°-~ p  max -3 211 p 11/B (14.41)  In the above the surface is assumed to be a diffuse (Lambert) scatlerer with cross section  <J = 4p(n/4)R28} cos </>, where p = surface reflectivity and </> angle between the surface  normal and the incident radar energy. These are only approximate equations. Losses should  be included for propagation through the atmosphere and in the system optics. 
 /Ê/ 
 The very low efficiency ofthis schemel makesit unsuitable for allbut avery few special applications, such assystems requiring variable interpulse intervals. Accordingly, inductance charging isalmost always used. Itwill beshown later that, ifad-c supply voltage isavailable, thenetwork voltage atthetime ofdischarge isdouble the supply voltage, except forlosses inthe inductance; itwill also be shown that the network can berecharged from asource ofa-cvoltage, provided the repetition frequency isamultiple ofone-half the supply frequency. 
 ! 474 HAS A WIDER BANDWIDTH THAN THE 6! 
 This data is the multipath error of a 2.7°  beamwidth S band (3-GHz) tracking radar that is tracking an aircraft target with a  beacon at 3300-ft altitude. An AN/FPS-16 tracking radar with a 1.1° beamwidth at  C band (5.7 GHz) was used to simultaneously track with its narrow beam, which  remained above the sea surface without significant multipath error, to provide a true  target altitude reference for the data in Figure 9.27. There is a measurement bias error  (observed in Figure 9.27) of about 0.25°. 
 5.7b, and the difference in Fig. 5.7c. The sum patterns is used for  transmission, while both the sum pattern and the difference pattern are used on reception. 
 STATE UNIT FOLLOWING  
 The abilities of the astronomical radars as unique and powerful information tools to measure physical properties and orbital parameters of asteroids are thoroughly analyzed and illustrated in [ 28]. Based on the aforementioned, the present work will focus on the passive ISAR scenario—kinematics and geometry—as well as signal modeling and special solutions in the asteroid’s imaging algorithm. 4. 
 I>amon~c, J. R., arid I). J. 
 23.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 Isodoppler Contours.  When the target is stationary and the transmitter and  receiver are moving (e.g., on airborne platforms), the bistatic doppler shift at the  receiver site fTR is  f TR = (VT /l) cos (d T  − q T) + (VR /l) cos (d R − q R) (23.12) where terms are defined in Figure 23.6. The locus of points for constant doppler shift on the Earth’s surface is called an  isodoppler contour , or isodop . 
 F~lectroniechanical phase-shifting devices. In addition to electronic phase shifters, electronie-  clianical devices for changing phase have been used in pliased-array radars, especially in the  early models. Although electroniechanical shifters are not now widely used, they are described  here to illustrate the variety of devices that might be employed in array antennas. 
 ALIASING FILTERING  DIRECT SAMPLING AT THE FINAL )& USING AN ANALOG 
 The type of transmitter— dedicated , cooperative , or non-  cooperative —completes the taxonomy. A dedicated transmitter is designed and   controlled by the bistatic or multistatic radar, analogous to a monostatic radar.   Both cooperative and noncooperative transmitters are transmitters-of-opportunity— designed for other functions, including radar and communications, but found suitable  for bistatic operation. 
 A typical value of the index of refraction at the surfaceRADARANGULAR ERRORAPPARENTTARGETPOSITION REFRACTED RAY TRUETARGET POSITION (c) RADARRADAR RAY IN THE PRESENCE OF REFRACTION RADAR RAY INTHEABSENCE OF REFRACTION RADAR HORIZON INTHEABSENCE OF REFRACTION RADAR HORIZON INTHEPRESENCE OF REFRACTION . of the earth is of the order of 1.0003. The Cosmic Ray Physics Laboratory (CRPL) standard atmosphere has been defined as one having an index of refrac- tion of 1.000313 (or 313 N units for the refractivity N) and having an exponential decrease of refractive index with altitude. 
 GAIN ANTENNA 4HIS REMEDY RESTORES THE SURVEILLANCE FRAME TIME LOST BY STEP SCANNING WHILE SIMULTANEOUSLY SERVICING MULTIPLE RECEIVERS (OWEVER  IT INCURS A DETECTION RANGE PENALTY BY THE REDUCED TRANSMIT ANTENNA GAIN AND ALSO SUF 
 Lalnh. J. J.: A noisc Silencing I.F. 
 LITES   4RANSMITTERS ARE LOCATED AT THREE SITES  THE LARGEST OF WHICH TRANSMITS  -7  #7 FROM A LINEAR ARRAY ABOUT  KM LONG  GENERATING A FIXED FAN BEAM 4HE SIX RECEIVE SITES CONSIST OF SEVEN OR EIGHT LINEAR ARRAYS WITH DIMENSIONS ON THE ORDER OF  KM  ALSO GENERATING FIXED FAN BEAMS COLLINEAR WITH THE TRANSMIT BEAM &IGURE  SHOWS THE DATA FLOW IN A TYPICAL RECEIVING STATION . 
                    
 BANDWIDTH PRODUCT HA VE BEEN USED TO ILLUSTRATE  THE VARIATION OF INSTANTA 
 Ward, H. R.: Dispersive Constant False Alarm Rate Receiver, Proc. IEEE, vol. 
 Generalization of spatially variant apodization to noninteger Nyquist sampling rates. IEEE T rans. Image Process. 
 3.30  3.10 Phase Detectors and Sync hronous Detector s  ........  3.32  Definitions and Characteristics  ...........................  3.32 Applications  ....................................................... 
 LOOKING BISTATIC 3!2  AND  THE "!# PROGRAM OPERATING WITH  !7!#3 FOR ALERTING AND CUEING SHORT RANGE  MOBILE  AIR 
 A widely used technique to broaden the spectrum of CW radar is to  frequency-modulate the carrier. The timing mark is the changing frequency. The transit time is  proportional to the difference in frequency between the echo signal and the transmitter signal. 
 Figure 4a is the single-channel independent processing reconstruction result, Figure 4b–d are the global sparse joint sparse reconstruction results. It can be seen from the ﬁgures that traditional single-channel independent processing can basically reﬂect the 3-D distribution of scattering points of the target, but cannot guarantee location consistency of all scattering points in different channels, which results in deviated location estimation. While with the proposed method, consistency of location and number of scattering points and more accurate reconstruction results can be ensured. 
 4.22~. Figure 4.22b shows the in-phase, or I, channel with the pulse train such  Doppler  I frequency Radar  echo  , Figure 4.22 (a) Blind speed in an MTI radar.  The target doppler frequency is equal to the  prf. 
  
 PASS  COVERAGE SUPPORTED INTERFEROMETRIC 3!2 MEASUREMENT OF !NTARCTIC GLACIAL FLOW RATES 2!$!23!4 
 For pulse modulation, thephases aresuch astomake the component waves add toamaximum periodi- cally. For example, ifone pulse is centered ontime t=O,the phases areallzero. Inthefrequency-mod- ulation case, the phases are such that the various components add to give aresult that varies more orless sinusoidally with time, but with con- stant amplitude. 
 R .. and D. J. 
    
 FIG. 1.1 Simple block diagram of a radar employing a power amplifier transmitter and a superheterodyne receiver. The operation of the radar is described in more detail, starting with the trans- mitter.ANTENNA DUPLEXERPOWERAMPLIFIERWAVEFORMGENERATOR LOW-NOISEAMPLIFIER LOCALOSCILLATOR MIXERIFAMPLIFIERMATCHEDFILTERSECONDDETECTORVIDEOAMPLIFIER DISPLAY . 
                               
 Swerling: Sequential Detection in Radar with Multiple Resolution Elements,  I RE Trans., vol. IT-8, pp. 237-245, April, 1962 .. 
 DOPPLER COUPLING 4IME SIDELOBE PERFORMANCE REMAINS EXCELLENT FOR LARGE DOPPLER SHIFTS!DEQUATE INSENSITIVITY TO DOPPLER TO ALLOW USE GENERALLY UP TO -ACH  4IME SHIFT OF F D4" IS  INTRODUCED BY RANGE 
 HEALTH  -ISSILE UPDATE PROVIDES THE LATEST TARGET INFORMATION AND FUTURE DYNAMICS PREDICTION  BY DATA LINK )2 MISSILE SLAVING CO 
 PROPAGATION OF RADAR WAVES 443  assurnes [flat 11, >) 11,. 'The phase difference corresponding to the path-length difference is  2n 2/1,/1, , - --- ---- radians  dl-A R  -1-0 this must be added the phase shift $, resulting from the reflection of the wave at M, which is  assumed to be n radians, or 180". The total phase ditTerence between the direct and the ground-  reflected signals as measured at the target is  'l'l~c rcst~ltatit of two siprials. 
 11.1, the input impedance ofaquarter-wave line shorted atthe farend isthe same asanopen circuit. When placed inparallel with themain line such aconnection hasnoeffect atallontheimpedance FIG. 112.-Simple quarter-wave stub FIG. 
 R.: Corrugated Waveguide Frequency Scanning Aerials, Proceedings International Con/er-  price on Radar-Present arrd Ftrtrrre, Oct. 23-25, 1973, IEE Conference Publication no. 105. 
 IEEE T rans. Geosci. Remote. 
 This is  called the spike-leakage energy. From 1 to 10 ergs of spike-leakage energy might be required to  burn out microwave crystal diodes. The amount of energy contained within the remainder of  the pulse after the initial spike is usually small and is not as serious as spike leakage. 
 REDUNDANT VEHICLE MANAGEMENT SUITE  AND A MULTIPLY 
 3(i2 7’IIEMAGNBTRO,V ANDTHE1’tiLSEIt [s1:(.108 supposed toappear and that atwhich itdoes appear, issometimes avery important factor tobeconsidered inthedesign ofthepulser (Chap. 16). For hard-tube pulsers, the time jitter ispractically allvays ofthe order of0,01 psec orless. 
 A., and H. G. Hopkins: Some Adverse Influences of Meteorological Factors on Marine Navigational Radar, Proc. 
 2.The TR-tube gap must fire inless than 0.01 psec, orthe preigni- tion “spike” ofmagnetron energy may burn out thecrystal. 3.The gap must deionize inafew microseconds attheend ofthemag- netron pulse sothat echoes from nearby objects will not beunduly attenuated. Atypical specification would demand less than 3-db attenuation 6psec aftqr the pulse. 
 The single  radar track states are then grouped with each other to produce a netted track state. The design decision as to which approach is better for grouping data depends on the  radars and targets involved. One case where detection-to-track association is clearly bet - ter is when the radars have a reduced probability of detection so there are potential gaps  in the data stream or periods where the data stream is sparse. 
 The standard analysis of the detectionperformance following integration assumes idealised processing, including matched ﬁltering, and actual non-ideal processing is accounted for through the addition of a signal processing loss. This will include a loss because the IF bandwidth of 3.5 MHz is wider than the ideal matched bandwidth of 1 MHz for a 1 μs pulse length. Here a signal processing loss of 8.5 dB has been included. 
 PP     4HE TERM  UT n TD  IS THE COMPLEX ENVELOPE OF THE TRANSMIT WAVEFORM DELAYED IN TIME  BY TD 4HE COMPLEX EXPONENTIAL EXP; JO  FDT n TD = REPRESENTS A LINEAR PHASE MODULATION  VERSUS TIME THAT IS IMPRESSED ON THE RECEIVED ECHO SIGNAL BY THE DOPPLER SHIFT  FD 4HE  CARRIER PHASE SHIFT IS PC   nO  FTD 4HE TIME DELAY AND DOPPLER SHIFT ARE EXPRESSED IN TERMS OF TARGET RANGE AND RANGE 
 Abramovich, N. K. Spencer, and S. 
 ( a) 2D distribution diagram of scattering point; ( b) 3-D distribution diagram of scattering point. T able 1. Simulation parameter. 
 WAVELENGTH FOCAL LENGTH  AND A GAUSSIAN FEED HORN A HORN WITH A RADIATION PATTERN DESCRIBED BY A GAUSS 
 As an explanation of the basic prin-  ciples of popular types of radar equipment the book is  in no sense a work of reference, and for this reason  sources are not quoted at length. However, in the pre-  paration of this work I have had the most generous  co-operation from the Services and Supply Ministries  concerned with radar’s production and operational use,  and from the research laboratories of the British and  American radio and radar industries.  7  . 
  
 13.17). Inhomogeneities oft he atmospheric  index of refraction generally do not produce strong enough backscatter to be a serious source  of clutter to most radars.  Birds. 
 .................441 12,3 Special Problems inRadar Receivers. 441 12,41 -fAmplifier Design... ... 
 ERATE ROCKS ALMOST COMPLETELY DEFY DESCRIPTION 3TATISTICAL DESCRIPTIONS OF SURFACES ARE USED FOR MOST THEORIES  SINCE A THEORY SHOULD  BE REPRESENTATIVE OF SOME KIND OF SURFACE CLASS  RATHER THAN OF A PARTICULAR SURFACE  AND SINCE EXACT DESCRIPTION IS SO DIFFICULT 4HE STATISTICAL DESCRIPTIONS THEMSELVES MUST BE OVERSIMPLIFIED  HOWEVER -ANY THEORIES ASSUME ISOTROPIC STATISTICS  CERTAINLY NOT APPROPRIATE FOR PLOWED FIELDS OR GRIDDED CITIES -OST THEORIES ASSUME SOME KIND OF MODEL INVOLVING ONLY TWO OR THREE PARAMETERS STANDARD DEVIATION  MEAN SLOPE  CORRELA 
 151-159, March, 1954.  4. Gabor, D.: Theory of Communication, J. 
 £n°È{  2!$!2 (!.$"//+    # ! 7ILEY  h3YNTHETIC !PERTURE 2ADARS! PARADIGM FOR TECHNOLOGY EVOLUTION v  )%%%  4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS  VOL !%3 
 Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar.  PULSE DOPPLER RADAR  4.476x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 where nN Ne=   1 2 2, , , ,pdi pdifor Swerling I targget (chi-squared distribution w ith 2 degre s ssoffreedom) for Swerling I I target (chi-s squared distribution w ith2 d egressofpdiN freedom) for SwerlingIIItarget(chi-squar red distribution w ith 4 degre ssoffreedom) ) for Swerling I V target (chi-squared distri ibution w ith4 d egressoffreedom)pdiN K x d Pd x m( ,) ,= −   12 2 = chi-squared distribution survival function72 Km−1( p,d ) = inverse chi-squared distribution survival function P xxt e dt t e dttx t( ,)( ,) ( )αγ α αα α= =− − − −∞∫ ∫Γ1 0 1 0 = regularized lower incomplete gamma function The integral of the chi-squared distribution Km(x,d ) and its inverse Km−1 ( p,d ) are often  included in mathematical computation software packages.73 When M-of-N detection (i.e., binary detection) is used within a dwell, the probabil - ity of detection for each look ( Pd,look) is used to compute the probability of detection  for a dwell ( Pd,dwell). When a dwell requires m detections out of n looks for a target  declaration, the Pd,dwell is  Pk nP Pd k mn dk dn , , , ( )dwell look look =   − =−∑ 1k k (4.26) For Alert/Confirm detection performance, the Pd for the Alert dwell and the Pd  for the Confirm dwell are individually computed as a function of SNR. 
 For instance, if there were 80 pulses  on target, one could batch 16 pulses, quantize this result to a 0 or a 1, and declare a target  with a 3-out-of-5 (or 2-out-of-5) binary integrator. The detection performance of the  batch processor for a large number of pulses integrated is approximately 0.5 dB worse  than the moving window. The batch processor has been successfully implemented by  the Applied Physics Laboratory20 of The Johns Hopkins University. 
 C5, pp. 3165–3180, 2003. 69. 
 ARRAY CONFIGURATIONS FOR DIGITAL BEAMFORMING WITH LOW SIDELOBES AND ADAP 
 It is obvious that the two ships are blurred and defocused in the SAR images. 286. Sensors 2019 ,19, 1154      (a) (b)  Figure 10. 
 has had wide application. Historically, the early radar experimenters worked almost  exclusively wit!, continuous rather than pulsed transmissions (Sec. 1.5). 
 OUSLY DEGRADE MORE NARROWBAND RADARS &REQUENCY AGILITY  DIVERSITY  AND INSTANTANEOUS WIDEBAND TECHNIQUES REPRESENT A  FORM OF %##- IN WHICH THE INFORMATION 
 73 1-743, May, 1970.  41. Guarguaglini, P. 
 Soc. Am ., vol. 52, pp. 
 FED REFLECTOR ANTENNA IS  M IN DIAMETER  RESULTING IN A BEAMWIDTH LESS THAN HALF THAT OF ITS + U BAND COUNTERPARTS 3EVERAL ADVANTAGES ARE CLAIMED FOR THE SMALLER  BEAMWIDTH  INCLUDING OPERATION CLOSER TO LAND /N THE OTHER HAND  THE NARROWER BEAM IMPLIES THAT THE WAVEFORM IS MORE SENSITIVE TO SPACECRAFT ATTITUDE ERRORS !LTI+AS  -(Z BANDWIDTH LEADS TO A PULSE 
 BAND CLUTTER LOOKING UPWIND AT A FEW DEGREES GRAZING  4HE PEAK FREQUENCY OF THE UPWIND  SPECTRUM APPEARS TO BE DETERMINED BY THE PEAK  ORBITAL VELOCITY OF THE LARGEST SEA WAVES  PLUS A WIND 
 END LOSSES ARE APPLICABLE TO BOTH TARGETS AND CLUTTER ,OSSES APPLICABLE  ONLY TO TARGETS WILL BE INDICATED 2& 4RANSMIT ,OSS  4HIS LOSS ACCOUNTS FOR 2& OHMIC LOSSES BETWEEN THE TRANSMIT 
 SCALE ROUGHNESS PROPERTIES  4HE SPACECRAFTS  
 Because the clutter is folded in both range and doppler with medium PRF, a number of PRFs may be required to obtain a satisfactory probability of sufficient detections to resolve the range and doppler ambiguities. The multiple PRFs move the relative location of the clear regions so that all-aspect target coverage is achieved. Since the sidelobe clutter generally covers the doppler region of inter- est, the ratio of the region with sidelobe clutter below noise relative to the total range-doppler space is a function of the radar altitude, speed, and antenna sidelobe level. 
 ENTRY  THE TARGET CONTINUES TO FALL BUT EXPERIENCES A DRAG ACCELERATION DUE TO ITS BALLISTIC COEFFICIENT AN UNKNOWN TARGET PARAMETER RELATED TO THE SHAPE AND MASS OF THE TARGET  !N )-- FILTER CAN BE USED TO SYSTEMATICALLY TRANSITION BETWEEN THESE DIFFERENT PHASES OF FLIGHT  PROVIDING A SINGLE FILTER OUTPUT &IGURE  SHOWS THE MODEL PROBABILITIES FOR SUCH AN )-- FILTER APPLICATION &)'52%   -ODEL PROBABILITIES RESULTING FROM THE APPLICATION OF AN )-- FILTER TO A BALLISTIC   MISSILE TRACKING PROBLEM  A  PROBABILITY THAT TARGET MOTION IS hBOOST PHASE v  B  PROBABILITY THAT TARGET  MOTION IS hEXO 
 24.60  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 28. G. V . 
 PULSE TRANSMITTER NOISE AS WELL AS POWER SUPPLY INSTABILITIES !LTHOUGH 4.# WORKS ONLY IN A SINGLE UNAMBIGUOUS RANGE INTERVAL  IT IS SAID THAT IT SHOULD BE ABLE TO OPERATE WITH SOME MEDIUM 02& RADARS IF SIGNIFICANT CLUTTER IS NOT LIKELY TO EXTEND OVER MORE THAN ONE 02& INTERVAL  .   4(% 2!$!2 42!.3-)44%2   £ä°Ó£ !N EXPERIMENTAL IMPLEMENTATION USING DATA COLLECTED ON AN OPERATIONAL RADAR WITH  A #&! TRANSMITTER SHOWED THAT hTHE 4.# TECHNIQUE CAN IMPROVE RADAR DETECTION OF TARGETS IN CLUTTER BY  D" OR MOREv £ä°ÇÊ ,  " /," 
 For purposes ofreducing interrogation byconfining ittoonly those interr~ gators that are intentionally seeking beacon replies, coding ofthe interrogation may beused. Likewise, the replies may bemade more complicated inavariety ofways forthe purpose either ofidentifying the beacon orofusing itasapart ofanauxiliary communication system. 8.7. 
 ENDED MIXER ONLY PROVIDES THE MODULUS OF THE TIME 
 The short-pulse area MTI has no blind speeds and can be designed to  have no range ambiguities. It is more attractive for application at the higher microwave  freqi~encies where the available bandwidths are large and the normal MTI suffers from exces-  sive blind speeds.  REFERENCES  1. 
 However, the cost of the fixed reflector of the parabolic torus is relatively cheap compared with  antennas which must be mechanically scanned. Nonutilization of the entire apertare is  probably not too important a consideration when overall cost and feasibility are taken into  account.  Figure 7.16 Principle of the parabolic-torus antenna. 
 Finally, the high-resolution 3D image is derived by synthesizing the 3D images from each sub-aperture. The proposed algorithm improves the imaging accuracy of both strong scattering centres and anisotropic targets. The procedure was tested by using both electromagnetic simulations and real data acquired in an anechoic chamber by using a prototype system. 
 ¤ ¦¥³ µ´ 
 RANGE SURVEILLANCE SCANS TO MONITOR DISTANT WEATHER 3INCE THE TRANSMITTED PEAK POWER IS TYPICALLY CONSTRAINED TO BE FIXED  THEN THE TRANSMITTED AVERAGE POWER INCREASES LINEARLY WITH  S !LSO  THE MATCHED FILTER BANDWIDTH AND ASSOCIATED NOISE  POWER DECREASES INVERSELY WITH  S )F THE RADAR PULSE VOLUME IS FILLED WITH DISTRIB 
 6. Brookner, E.: "Aspects of Modern Radar," Artech House, Norwood, Mass., 1988. 7. 
 Bothamean-level o RadiolvelocityFilternumber 5 6 prf -I prf -2 Aircraft aliases8 2 3 4 5 True aircraft velocityFigure4.28Detection ofaircraftin rainusingtwoprf'swithadoppler filterbank, illustrating theeffectof dopplerfoldover. (FromMuehe,43 Courtesy IEEE.). M'rt AND PIJI.SE DOPP1,ER RADAR 129  tlircshold frorn tlie 16 range cells and a clutter thresliold from the clutter map are calcitlated  for filters 2 and 8 adjacent to the zero-velocity filter, and the larger of the two is used as the  threshold. 
 2.2 Experimental results showing the effect of bandwidth (parameter BT) on 90 percent probability detectability factor D^90), with pulse repetition fre- quency (PRF) as a parameter. The experiments were performed during World War II at the MIT Radiation Laboratory. (From Ref. 
 7- 11, 1991  − S. Riegger, W. Wiesbeck, D. 
 FREQUENCY WAVES USING A WAVE FOLLOWER v  * 'EOPHYS 2ES  VOL   PP n    7 * 0IERSON AND , -OSKOWITZ  h! PROPOSED SPECTRAL FORM FOR FULLY DEVELOPED SEAS BASED ON THE  SIMILARITY THEORY OF 3 ! +ITAIGORODSKII v * 'EOPHYS 2ES  VOL   PP n  .   3%! #,544%2  £x°Î  / - 0HILLIPS  h3PECTRAL AND STATISTICAL PROPERTIES OF THE EQUILIBRIUM RANGE IN WIND 
 ING APPLICATIONS )N ADDITION TO PROVIDING INFORMATION ABOUT THE SEA SURFACE  (& RADAR CAN BE USED  TO INFER SURFACE WIND SPEED AND DIRECTION   7IND DIRECTION IS COMMONLY ESTIMATED  BY TAKING THE RATIO OF THE FIRST 
 Lab. Kept. 8579, May 1982. 
 Thearrangement in(g)canbe trainedontargetwithminimum rateoracceleration requirements onallaxes,irrespective of theposition ofthetargetormotionoftheplatform. Inthethree-axis arrangement of(h)a stablebaseisprovided inwhicharollaxisliesinafixedposition paralleltothefore-and-aft lineofthevehicle.Thisaxiscarriesthepitchaxisthatsupports thetrainaxis.Pitchandroll signalsfromastableverticalareappliedasinputstothecorresponding axes.Theresultisthat theazimuth (ortrain)axisisstabilized intheverticalandmayreceiveadirectorderofrelative azimuth. Computations arenotrequired asinothermounts. 
 As .will be described later, the effect of blind speeds can be  significantly reduced, without incurring range ambiguities, by operating with more than one  pulse repetition frequency. This is called a staggered-pr_{ MT/. Operating at more than one RF  frequency can also reduce the effect of blind speeds. 
 A. Morain and D. S. 
 [ CrossRef ] 17. Xiao, W.; Liu, W.; Sun, G. Modernization milestone: BeiDou M2-S initial signal analysis. 
 In the literature165,166 some critical aspects, in  terms of jammer receiver sensitivity and transmitted power, for spot-noise jamming  are considered and the system requirements are derived to determine the feasibility  and practicality of such jammer. Results of a computer simulation of an engagement  between SAR and representative jamming system are given to enable the effective - ness of ECM to be assessed. The threats to a SAR are barrage jamming, spot jamming, random pulse jamming,  and repeater jamming. 
 weighting of the received signals, similar to the weighting of the aperture  illumination of a real antenna, is often applied to reduce the sidelobe levels.  Constraint on resolution and swath. Ambiguities can arise when signals are sampled, rather  than continuous. 
 POLAR GRATING LOBES 4HIS CAN BE ACHIEVED WITH A PRINTED POLARIZATION FILTER IN FRONT OF THE ARRAY OR BY EFFECTIVELY CREATING  AS PART OF THE STRUCTURE  A SHORT LENGTH OF OPEN 
 TO 
 VARYING PRIORITIES 4HESE WILL GENERALLY INVOLVE DIFFERENT WAVEFORMS  TASK 
 F. Smith: Radar Scattering from a Conducting Cone-Sphere,  MIT Lincoln Laboratory Tech. Rept. 
 Based on this fact, the knowledge of the spatial coherence property is fully exploited in KA-DBS. And then, the spatial continuity model of the radar echo is constructed. In order to well estimate the pulses information outside the observed coherent processing interval (CPI), the forward prediction pulses and the backward prediction pulses are estimated based on the autoregressive (AR) technique [ 20–22], respectively. 
 NOISE AMPLIFIER 4HIS LOSS MAY BE INCLUDED IN THE RECEIVE SYSTEM NOISE FIGURE OR SYSTEM TEMPERATURE VALUE )& -ATCHED &ILTER ,OSS  4HE MATCHED FILTER FOR A PULSE DOPPLER WAVEFORM INCLUDES  THE ANALOG )& MATCHED FILTER IN THE RECEIVER AND ANY SUBSEQUENT DIGITAL INTEGRATION OF !$ SAMPLES TO MATCH THE DURATION OF THE TRANSMIT PULSE )& MATCHED FILTER LOSS QUANTI 
 6.21  Multiple-Reflector Antennas  ...............................  6.23  Special-Purpose Reflectors  ................................  6.26  6.4 Feeds  ...................................................................... 
 6. Ib is plotted in rectangular coordi- nates, with the vertical axis in decibels. This is by far the most widely used form of plotting patterns because it provides a wide dynamic range of pattern levels with good visibility of the pattern details. 
 If,forexample, theelement spacing were0.5Aoandlid=15,thebeamcanbescanned from 00=0to00=62°.(Thisassumes thelowestfrequency isdetermined bythecondition thatthe element spacing benotlessthanone-half wavelength.) Withd=0.6Ao,thebeamcanbe scanned from-48°to+36°without theappearance ofgratinglobes,forlid=15.. 1111: I:I 1:C.I RONIC'AI I Y SIEEREI) PtIASED ARRAY ANTENNA IN RADAR 301  It is possible for a frequericy-sca11 array to etnploy different frequericies to radiate over the  qarne angular region, assunling that the antenna feed and elements are sufficiently  broadband.64 This can be seen from an examination of Eq. (8.176). 
 Xue, X.; Song, L.; Jia, L.; Le, Y.; Ge, H. New prediction method for postconstruction settlement of soft-soil roadbed of expressway. Chin. 
 By early June the range was  25 miles.  It was realized by the NRL experimenters that higher radar frequencies were desired,  especially for shipboard application, where large antennas could not be tolerated. However,  the necessary components did not exist. 
           
 OBSERVING SPACE 
 POWER RADARS INTENDED  PRIMARILY FOR OCEANOGRAPHIC REMOTE SENSING  ESPECIALLY OF OCEAN CURRENTS  AND  II  LARGER AND MORE POWERFUL SYSTEMS WITH TARGET DETECTION AS  THEIR PRIMARY MISSION  4HE FORMER ARE IN WIDESPREAD OPERATION AROUND THE WORLD ONLY A FEW OF THE LATTER ARE OPERATIONAL IN SURVEILLANCE ROLES 4HE ABILITY OF THE LOW 
 Impedance matching is providecl at the  input and output toroids. By filling the center slot of the toroid with high dielectric-constant  material a better figure of merit and lower switching power are obtained, but the peak power  capability is decreased. The individual toroids are usually separated by thin ciielqctric spacers  to avoid magnetic interaction (Fig. 
 Indiplexoperation thetwofrequencies areradiated onorthogonal polarizations. Frequency andpot"arization diversity canprovide an improved signal-to-noise ratiobycon­ vertingaSwerling type1target(Sec.2.8)withscan-to-scan fluctuations toaSwerling type2 withpulse-to-pulse fluctuation. From4to7dBimprovement insignal-to-noise ratiomightbe achieved inthediplexmodeascompared withthesimplexmode.46 TheARSR-3 utilizesaklystron amplifier toachieve 5MWpeakpowerand3.6kW averagepower.Thereceiver front-end isalow-noise transistor with4dBnoisefigure.The logarithmic receiverisfollowed byaCFARwhichdividestheamplitude ofeachrangesample inthelogarithmic outputbytheaverageamplitude ofthereturnswithininmiofthatsample. 
 ¤ ¦¥³ µ´  P L3# "EAM    WHERE 6"EAM IS THE VELOCITY ON THE SURFACE OF THE ILLUMINATING FOOTPRINT OF THE AZIMUTH  ANTENNA PATTERN 4HE TIME DERIVATIVE OF THE PHASE YIELDS THE SCATTERERS DOPPLER HISTORY   FT66 2T$ 
 AREPS has many other data display features. For example,  the propagation factor values as shown in Figure 26.16 may also be exported in a  number of different text formats for use in other engineering applications. REFERENCES  1. 
 The distance, or range, to the target is determined by measuring the  time TR taken by the pulse to travel to the target and return. Since electromagnetic energy  propagates at the speed of light c = 3 x 108 m/s, the range R is  R = cTR  2 ( 1.1)  The factor 2 appears in the denominator because of the two-way propagation or radar. With  the range in kilometers or nautical miles, and TR in microseconds, Eq. 
 (After Allen.5*) FIG. 7.15 Scattering-matrix model for a two-element array. is the vector sum of the couplings from all elements, including its own reflection as a self-coupling: V1' = C11 V1 + Cn V2 V2' = C21 V1 + C22 V2 The reflection coefficient in each element is obtained by dividing the reflected voltage by the incident voltage in the channel: _ V1' _ V1 V2 r' ~ "vT ~ c" v;+ C|2 V1ANGLE (degrees) ANGLE (degrees)E-PLANE SCAN SHORT DIPOLES, NOGROUND PLANE,S/X =0.1IrJ2 H-PLANE SCAN SHORT DIPOLES, NO GROUND PLANE S/X = 0.1 SELF COUPLING MUTUAL COUPLING . 
    &EBRUARY     UNCLASSIFIED REPORT  $ ,YNCH  h3IGNAL PROCESSOR FOR SYNTHETIC APERTURE RADAR v PRESENTED AT 30)% 4ECHNICAL  3YMPOSIUM %AST   PAPER NO  
 Byfeeding r-fpower into the ends ofthe array alternately, atotal scan of60” isrealized. This alternate-end technique isalways used inpractice with the Eagle scanner; itisaccomplished with theaidofafast-acting r-fswitch which operates synchronously with the guide-squeezing mechanism. The azimuth beam angle 8isrelated totheguide width a,thedipole spacing sand thefree-space wavelength AObytheformula Here 0ispositive inthe end-fire direction. 
 It is inherent that synthetic antenna radars and pulse compression radars require the storage of radar data, because the data for synthetic antenna generation does not occur simultaneously but is collected over some interval of time. Operations are then performed on these signals to achieve the selectivity of the radar. Moreover, each radar return participates in forming the output for a large number of points on the output map. 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar.  TRACKING RADAR  9.476x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 This approach can reduce errors by two effects. First, as observed in Figure 9.28, the  magnitude of the elevation multipath error reduces in direct proportion to the beam - width. 
 4(% 
 COMPRESSION RADAR %#- AND %##- v  $EF %LECTRON  VOL     PP n  /CTOBER   ( +USHEL  h6(&5(& 0ART  CHARACTERISTICS v  %LECTRONICS  #OMMUNICATIONS %NGINEERING  *OURNAL  VOL   NO   PP n  !PRIL   2 * 'ALEJS  h6OLUME SURVEILLANCE RADAR FREQUENCY SELECTION v  0ROC OF )%%%  )NT 2ADAR  #ONF  !LEXANDRIA 6!   53!  -AY n    PP n  ( +USHEL  h6(&5(& 0ART  OPERATIONAL ASPECTS AND APPLICATIONS v  %LECTRONICS    #OMMUNICATIONS %NGINEERING *OURNAL  VOL   NO   PP n  *UNE   7 . $AWBER AND . - (ARWOOD  h#OMPARISON OF DOPPLER CLUTTER CANCELLATION TECHNIQUES FOR  NAVAL MULTI 
 TION CHALLENGES  AND THE WIDE REAL 
 This expression for the  doppler-tQlerant waveform is difficult to interpret as it stands, but if the natural-log factor is  expanded in a series, Eq. ( 11.55) becomes  (11.56)  When terms greater than the first two can be neglected (which applies when 2rr.B2t3 <{ 3f0 T2),  Eq. ( 11.56) reduces to the classical linear FM waveform. 
 TANK MEASUREMENT OF RADAR SCATTERING FROM AN  EVOLVING BREAKING WAVE  CORRELATED WITH WAVE SURFACE HEIGHT VARIATIONS  FROM - ! 3LETTEN AND * # 7EST   Ú 4HE !MERICAN 'EOPHYSICAL 5NION  -ETERS 4IMES  A  B !#!& #"          $!%#$!   ! $! #%# !    #$ 
 On the other hand. the radars cannot be placed too far apart since the curvature  of the earth will limit the minimum altitude al which targets can be seen. For example. 
 With manufacturers continually producing  ch25.indd   37 12/20/07   1:40:45 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 
 LIKE AMBIGUITY FUNCTION  5SED  THEREFORE  FOR LOW 
 This type of filter is termed finite  impulse response because an impulse presented  at the input (a single sample of “1” surrounded by samples of zeroes) would produce  a finite-length output, consisting of the coefficients of the filter output in order as  the “1” propagates down the shift register, as shown in Figure 25.31 for a FIR filter  with seven coefficients (commonly referred to as a 7-tap FIR filter). In this example,  zero-valued samples are first clocked into the FIR filter shift register, filling the shift  register with zeroes and forcing the filter output to be zero. When the sample with a  value of “1” is clocked into the filter, the filter output produces the first coefficient, a0,  since the other samples in the filter are still zero. 
 STABILIZATION 4HE RADAR PACKAGE REQUIRED AN AVERAGE  7 INPUT POWER AND HAD A MASS OF  KG 0EAK TRANSMITTED POWER WAS  7  4HE 8 BAND AND 3 BAND COMMUNICATIONS  SYSTEM USED A DESPUN ANTENNA ^  M DIAMETER DISH  4HE RADAR ALTIMETER PROVIDED MANY  YEARS OF DATA WITH A HEIGHT ACCURACY OF  M  WHICH WAS THE BEST AVAILABLE INFORMATION ON 6ENUS SURFACE FIGURE UNTIL  -AGELLAN 4HE ALTIMETERS WAVEFORM STRENGTH AND SHAPE  WERE ANALYZED TO ESTIMATE SURFACE ELECTRICAL CONDUCTIVITY AND METER 
 Y . Kim and J. van Zyl, “Vegetation effects on soil moisture estimation,” Proc. 
 Van Brunt, Applied ECM , vol. 1, Dunn Loring, V A: EW Engineering, Inc., 1978. 14. 
 The usual method of measuring the direction of arrival is with narrow antenna beams. If  relative motion exists between target and radar, the shift in the carrier frequency of the  reflected wave (doppler effect) is a measure of the target's relative (radial) velocity and may be  used to distinguish moving targets from stationary objects. In radars which continuously track  the movement of a target, a continuous indication of the rate of change of target position is  also available. 
 BASED .,&- WAVEFORM AS  A FUNCTION OF K 
 The performance of common types of pulse compression systems is summa- rized in Table 10.1. The systems are compared on the assumption that informa- tion is extracted by processing a single waveform as opposed to multiple-pulse processing. The symbols B and Tare used to denote, respectively, the bandwidth and the time duration of the transmitted waveform. 
 Not  all states need to be measured for each element, but eliminating measurements at some  of the states will cause the calibrated amplitude and phase errors to increase.108 Phase shifters usually exhibit small variations in amplitude over phase states,  whereas attenuators exhibit large variations in-phase over gain states. Therefore, it is  desirable to calibrate the attenuator first. The phase shifter can then be calibrated with - out changing the attenuator setting.108 Once the characteristics of each T/R channel are  measured, correction factors are calculated and stored for future use. 
 APERTURE IMAGING RADARS ARE CAPABLE OF MEASURING THE FULL COM 
 L.: Radar Antennas, chap. 25 of "Antenna Engineering Handbook," H. Jasik, (ed.),  McGraw-Hill Book Company, New York, 1961, sec. 
 146] SPEED REGULATORS 577 having the regulating field, removal ofthe regulator from the circuit kills thealternator voltage. Inorder toget good results bythis method, the motor field must operate below saturation; this adds weight tothemagnetic circuit. TunedCircuit C’ontrol.-An interesting method ofspeed control has been used bythe Holtzer-Cabot Electric Company intheir MG-153 inverter, Fig. 
 113. Atlas, D.: Meteorological "Angel" Echoes, J. Meteorol., vol. 
 A block diagram of the FM-CW radar with a sideband superheterodyne receiver  is shown in Fig. 3.13. A portion of the frequ~ncy-modulated transmitted signal is applied to a  mlxer along with the oscillator signal. 
 Figure 15.2 shows the combined results ofa 1SeeSec. 2.14. 2SeeSew. 
 TANEOUS RECEIVE BEAMS CAN BE USED TO TRADE ENERGY FOR A REDUCTION IN THE VOLUME SEARCH  FRAME TIME 4HE USE OF MULTIPLE SIMULTANEOUS RECEIVE BEAMS WILL REDUCE THE SEARCH FRAME  TIME  SINCE MANY BEAM POSITIONS ARE SEARCHED AT THE SAME TIME 7HEN USING MULTIPLE SIMULTANEOUS RECEIVE BEAMS  THE TRANSMIT BEAM CAN BE BROADENED BY BEAM SPOILING SO THAT THE  
 POLARIZED RETURNS AT  '(Z AT A GRAZING ANGLE OF  WERE REPORTED  BOTH WITH  VALUES CLOSE TO n D"  4HE 3PECTRUM OF 3EA #LUTTER  4HE SCATTERING FEATURES PRODUCING  SEA CLUTTER ARE  ASSOCIATED WITH A SURFACE SUBJECT TO SEVERAL TYPES OF MOTION 4 HE FEATURES THEMSELVES  MAY BE MOVING WITH SMALL GROUP OR PHASE VELOCITIES OVER THIS SURFACE WHILE THE SURFACE ITSELF IS MOVED  IN TURN  BY THE ORBITAL VELOCITIES OF THE LARGER WAVES PASSING ACROSS IT  OR THE FEATURE MAY BE ADVECTED AT THE VELOCITY OF THE WAVE SYSTEM SUPPORTING IT 4HE SCATTERERS MIGHT EVEN BE DETACHED FROM THE UNDERLYING SURFACE  AS IN THE PLUMES EMIT 
 An example of the latter is the  theta-theta  location technique, where  RR = L cosq T / sin (qT − qR ) (23.15) and qT  − qR = b . A dedicated or cooperative monostatic radar can provide values of  q T directly to the hitchhiker. Otherwise, the hitchhiker must estimate the value, for  example, via an emitter locator measuring the radar’s antenna scan rate when it is pre - dictable. 
 115V30 Ifield#1 o! IAo B26v1’$ = ~O115v30 IAlternator I D0.+28V ‘<inputpowerLtield#2 -I G- AlternatorI L– FIG. 1419.-Schematic circuit ofHoltzer-Cabot MG-153 aircraft motor-alternator. output ratings: 750va,115volts,4Q0cpa, 3-phase; 250 va, 26 volts, 400 cps, l-phase. 
 Tech.  Rept. 424, October 1966. 
 Subsequently a fixed digital taper, after the formation of sub-arrays, is applied with a  set of weights for the sum and a different set of weights for each difference channel.  This is schematically illustrated in Figure 24.8 for a uniform linear array (ULA) that  generates a sum and a difference channel. The figure depicts a ULA with 24 receiving  elements clustered into four not overlapping and not regular sub-arrays.118 The calculation of analogue taper is made by resorting to the nulling of fictitious  wide angle jamming, which occupies the whole angular sector where sidelobes of  sum and difference beams have to be kept low. 
 Skolnik. M. I.: Millimeter and Submillimeter Wave Applications. 
 #7 WAVE 
 Sometimes a slit is cut in the side wall of the waveguide to  reduce the eddy currents. Another factor that complicates operation is hysteresis which causes  the value of permeability to differ for increasing and decreasing current. To eliminate hyster­ esis errors a current pulse must be applied to the phase shifter solenoid to drive the ferrite to  Ferrite  toroid /  (a)  Dielectric D,electric  matching spacers  transformer  Latching Fer rite  conductor toroid  (Drive wire)  (b)  Figure 8.10 (a) Single bit of a latching ferrite phase-shifter mounted in waveguide; (b) sketch or five-bit  latching ferrite phase-shifter. 
 OPED TO SUPPORT THE COMMUNICATION INDUSTRY  SUCH AS DIGITAL UP 
 E.: Fundamental Limitations in RF Switching and Phase Shifting Using Semiconductor  Diodes, Proc. IEEE, vol. 52, pp. 
 It is difficult to  estitnate this correction. The resolution cell is not likely to be completely filled at long range or  when the beam is viewing tlie edge of a precipitation cell. If the " bright band" (to be described  later) is within the radar resolution cell, the precipitation also will not be uniform. 
 TABLE 19.6  Relevant Nexrad System Characteristics69 Transmitted Peak/Average Power (klystron) 750 kW / 1500 W Pulse length 225, 675 m (1.57, 4.50 µs) Polarization Linear horizontal Wavelength 10.6 cm Receiver noise temperature 450 K Dynamic range 95 dB Antenna gain 45.5 dB Beamwidth 0.95° Sidelobe levels < –27 dB Maximum range (reflectivity data) 460 km Maximum range (doppler data) 230 km Unambiguous velocity ± 50 m/s Clutter suppression (maximum)  55 dB System sensitivity –7.5 dBZ at 50 km Rotation rate 10–30 deg/sec FIGURE   19. 2 Nexrad WSR-88D radar at  Missoula, Montana, mounted on 15-m tower with  two equipment shelters—one containing the trans - mitter, receiver, processor, and communications  equipment, and the other containing a standby gen - erator ( Photo courtesy of NOAA/NWS ) ch19.indd   16 12/20/07   5:38:17 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Ad-c bias winding issometimes used tocontrol thepoint atwhich theimpedance suddenly drops from itshigh value. Virtues claimed forthe nonlinear inductance switch arelong life, ruggedness, and simplicity. The switch can beoperated atpulse repetition frequencies upto4000 pps and at power levels inexcess ofseveral hundred kilowatts. 
 Unfortunately, the application of the Sequential Observer to radar is limited. At any  particular antenna position a radar normally observes many range resolution intervals, per-  haps several hundred. At each range interval within the biamwidth of the antenna a decision  has to be made concerning the presence or absence of a target before the antenna beam can be  positioned to a new direction. 
 Curves for Visual Detection. The curves of Figs. 2.3 to 2.7 apply when the detection decision is based on an automatic threshold device as described. 
 Lee. Y. W.: Application of Statistical Methods to Communication Problems, MIT Research Lab. 
 The first instrument  (from France) is part of the payload on India’s Oceansat-3. AltiKa78 is single-frequency  since at Ka band the retardation due to the ionosphere is sufficiently small that it does  not have to be measured and compensated. However, the ∼0.84 cm wavelength is  vulnerable to atmospheric moisture; it is predicted that as much as 10% of the data  will be compromised by rain. 
 The four parameters are complex  amplitudes, meaning that a scattering object is described by 8 scalar magnitudes.  They co n- tain all in formation about the scattering behaviour of an object with frequency, object orient a- tion, sender and receiver position.  Thus far the scattering matrix has been defined in a linear  framework (in the following: ξ, η  for h,v), since in practice linear polar ized antennas are e m- ployed. 
 SWITCHING RECTIFIER  SPARK GAP  OR MAGNETIC (OWEVER  THE SOLID 
 Zachary: Phase-Amplitude Monopulse System, IRE Trans., vol. MIL-6, pp.  140-146, April 1972. 
 6.6] PLANE DIL5’PLA YS INVOLVING ELEVATION 171 Range isalways plotted vertically, and atshort range the resolu- tion inangle isfargreater than that afforded bythe PPI. This display, called “type B,” (shown inFigs. 6“7and 68) isused in situations where thechief considerations aretherange and bearing ofpoint targets orgroups oftargets, with little ornoimportance attached totheshapes ofextended targets ortherelative locations ofwidely separated targets. 
 They ‘flip’ over into a stable con-  dition, and remain in this state until (usually due to the  charge or discharge of a grid condenser) they again  became unstable and ‘flop’ back to the original stable  condition. Sometimes the internal changes taking place  after the ‘flop’ send them automatically—+.e., with no  external cause—into an unstable state again, and they  continue ‘flip-flopping’ of their own accord. Such a  circuit is the true multi-vibrator. 
 Spacecraft mass was 1035 kg; the radar mass was 335 kg.  Input power was 210 W at 28 VDC. Magellan  operated at S band (2.385 Ghz),  radiating a peak power of 325 W. 
 The  wideband waveform has a swept bandwidth of 1000 MHz, to a pulsewidth of approxi - mately 250 µs, and a LFM slope B/T ≈ 1000 MHz/(250 µs) = 4 MHz/µs. The range  window width for the 3.2 MHz processing bandwidth is   ∆rcB B Tm s p= =×=2150 3 2120( / ). µ µMHz 4MHz sm  Millimeter Wave Radar. 
 Simmons, S.; Evans, R. Maximum likelihood autofocusing of radar images. In Proceedings of the IEEE 1995 International Radar Conference, Alexandria, VA, USA, 8–11 May 1995; pp. 
 PORT DEVICES THAT  IN BASIC FORM  HAVE THE INPUTS AND OUTPUTS LOCATED AT RIGHT ANGLES TO EACH OTHER (OWEVER  THE MAGIC 4S HAVE BEEN DEVELOPED IN CONVENIENT hFOLDEDv CONFIGU 
 63. G. E. 
 Thusachangeinthethreshold ofonly1.77dBchanges thefalse-alarm timebyfiveordersof magnitude. Suchisthenatureofgaussian noise.Inpractice, therefore, thethreshold level wouldprobably beadjusted slightlyabovethatcomputed byEq.(2.26),sothatinstabilities whichlowerthethreshold slightlywillnotcauseafloodoffalsealarms. Iftherecelver wereturnedoff(gated)forafractionoftime(asinatracking radarwitha servo-controlled rangegateoraradarwhichturnsotTthereceiverduringthetimeoftransmis­ sion),thefalse-alarm probability willbeincreased bythefractionoftimethereceiver isnot operative assuming thattheaverage false-alarm timeremains thesame.However, thisis usuallynotimportant sincesmallchanges intheprobability offalsealarmresultineven smallerchanges inthethreshold levelbecauseoftheexponential relationship ofEq.(2.26). 
   2%&,%#4/2 !.4%..!3   £Ó°Î£ £Ó°xÊ , 
 28.Rowlands, R.0.:Detection ofaDoppler-Invariant FMSignalbyMeansofaTapped DelayLine.J. Aroust.Soc.Am.,vol.37.pp.608-615. April.1965. 
   PP  
 #ONTROLLED 4UBES  4HERE HAS BEEN IMPORTANT APPLICATION OF  THE GRID 
 In GPR applications, the effect of combinations of scat - tering planes, for example, the corner reflector, can cause “bright spots” in the image,  and variations in the velocity of propagation can cause dilation of the aspect ratio of  the image. Although many images can be focused to reduce the effect of antenna beam  spreading, regeneration of a geometric model is a much more complex procedure and  is not usually attempted. The general objective of signal processing as applied to GPR is to present either  an image that can readily be interpreted by the operator or to classify the target return  with respect to a known test procedure or template. 
 The success ofthis experiment ledthe British todesign ahlgher- frequency radar specifically forthepurpose ofclose control, and resulted inthe modification ofthefirst ofthe.American 10-cm sets, onitsarrival inEngland, tofititforsimilar close control. Because ofthe -African experience the control setup was made mobile. Figure 7“11shows the Antenna lpereporting &-> Telephone I/i/i ll\+Tria@atio= ;me:nt K&’andbriefing FIG.7.11.—Layout Ofradar control center. 
 KIND "ESSEL FUNCTION 4HE AUTOCORRELATION FUNCTION OF HEIGHT WITH DISTANCE IS SELDOM KNOWN FOR TERRAIN   ALTHOUGH IT CAN BE DETERMINED ON A LARGE SCALE BY ANALYSIS OF CONTOUR MAPS  AND IT  HAS BEEN FOUND FOR SOME AREAS BY CAREFUL CONTOURING AT CLOSE INTERVALS AND SUBSEQUENT  ANALYSIS "ECAUSE OF LACK OF KNOWLEDGE OF ACTUAL AUTOCORRELATIONS  MOST THEORY HAS BEEN DEVELOPED WITH ARTIFICIAL FUNCTIONS THAT ARE CHOSEN MORE FOR THEIR INTEGRABILITY THAN FOR THEIR FIT WITH NATURE SELECTION AMONG THEM HAS BEEN ON THE BASIS OF WHICH ONES YIELD THE BEST FIT BETWEEN THEORETICAL AND EXPERIMENTAL SCATTER CURVES 4HE CORRELATION FUNCTION FIRST USED  WAS GAUSSIAN   QX    E  
 7.29,  7.30)Method of  Covariance  PropagationAdvantages Disadvantages Polar Kalman  filterPolar Polar Eqs. 7.29 to  7.33 in polar  coordinatesFilter covariances  are calculated  exactly and state  errors gaussian  distributed. Radar  detections of  less than three  dimensions can  be used.Pseudo- accelerations  introduced  in state  propagation. 
 This ischiefly amatter ofmaking proper choice of frequency, transmitter power, and antenna characteristics. 2.The data signals should, asfaraspossible, bemade unlike the expected interference insignal characteristics, and every advantage should betaken ofthese differences inthe receiving equipment. 3.Incertain cases afavorable signal-to-interference ratio can be enhanced bytechniques such asthe use ofwide deviation ratios with frequency modulation. 
 49. C. Rife and R. 
 and tlie Woodward-Levinson method gives an antenna pattern  wliicll exactly fits tile desired pattern at a finite number of points.  I)olpl~-('l~i~l~ysl~cv arrays.'" ' 'I'liis pnttc~ri produccs the ~larrowest beamwidtli for a specificcf  sidciol~c Icvcl l'lic l>ea~nw~dtli is rneasut-cd by the distance between the first nulls that straddle  tlic r~inr~i t>cnrii I'lie sidelol>cs arc all of equal magnitude. DolpliSO derived the aperture  illutiiiliatiori w~tli tli~s property by forcing a correspondence between the Chebyshev poly-  rlotiiial arid the polyllornial describing the pattern of an array antenna. 
 BEAM DEPRESSION ANGLE RELATIVE TO LOCAL HORIZONTAL  RADIANS  P   MAIN 
 The amount of this data can be great and often limits the area over which fine resolution can be obtained. A description of what needs to be done is given in Refs. 12 and 13. 
 The choice of polarization· also influences the a·mount of sea or land absorption.  Vertical polarization is absorbed more than horizontal.  The total antenna temperature can be found by integrating the temperature" seen" by the  antenna, weighted by the antenna gain over the entire sphere.60  , T, :__· J Ts(fJ, cp )G(O, cp) dQ  a -J G(O, cp) dQ (12.17)  where dQ = solid angle given by sin O dO dcp. 
 Examples of  early concepts that were well ahead of the available technology were the velocity indicat - ing coherent integrator (VICI)1 and the coherent memory filter (CMF).2,54 Although these improvements have enabled much improved MTI capabilities,  there are still no perfect solutions to all MTI radar problems, and the design of an MTI  system is still as much of an art as it is a science. Examples of current problems include  the fact that when receivers are built with increased dynamic range, system instability  limitations will cause increased clutter residue (relative to system noise) that can cause  false detections. Clutter maps, which are used to prevent false detections from clutter  residue, work quite well on fixed radar systems, but are difficult to implement on, for  example, shipboard radars, because as the ship moves, the aspect and range to each  clutter patch changes, creating increased residues after the clutter map. 
 476-481, February, 1958.  33. Kell, R. 
 159.Ruvin,A.E.,andL.Weinberg: DigitalMultiple Beamforming Techniques forRadar,IEEE EASCON '78Record,pp.152-163, Sept.25-27,1978,IEEEPublication 78CH1354---4AES. 160.Malagisi, C.S.:Microstrip DiscElement Rel1ectArray,IEEEEASCON '78Recurel,pp.186-192. Sept.25-27,1978,IEEEPublication 78CH1352-4AES. 
 COORDINATE SYSTEM  THE TWO COORDINATES  P  AND E DEFINE POINTS  ON THE SURFACE OF A UNIT HEMISPHERE !S SHOWN IN &IGURE    P  IS THE ANGLE OF SCAN  MEASURED FROM BROADSIDE AND  E IS THE PLANE OF SCAN MEASURED FROM THE  X AXIS 6ON  !ULOCK HAS PRESENTED A SIMPLIFIED METHOD FOR VISUALIZING THE PATTERNS AND THE EFFECT  OF SCANNING (E CONSIDERS THE PROJECTION OF THE POINTS ON A HEMISPHERE ONTO A PLANE &IGURE   THE AXES OF THE PLANE ARE THE DIRECTION COSINES COS  @ X  COS @Y &OR ANY  DIRECTION ON THE HEMISPHERE  THE DIRECTION COSINES ARE  COS SIN COS COS SIN SINAF AFX Y   P P  4HE DIRECTION OF SCAN IS INDICATED BY THE DIRECTION COSINES COS  @XS  COS @YS (ERE  THE PLANE OF SCAN IS DEFINED BY THE ANGLE  E MEASURED COUNTERCLOCKWISE FROM THE COS  @X AXIS AND IS GIVEN BY   FA A 
 Hybridjunctions canalsobeused.These produce a1800phasedifference betweenthetwooutputsignalsandrequireaslightlydifferent designprocedure.IOO ItisofinteresttonotetherelationoftheButlernetwork totheFastFourierTransform (FFT).Asstatedpreviously, theradiated fieldofanantenna isrelatedtotheillumination acrosstheaperture bytheFouriertransform. Shelton93haspointedoutthattheflowdiagram oftheFFTisbasically similartothediagram oftheButlernetwork. ThustheButlernetwork isamanifestation oftheFFT.Theantennaequivalent oftheconventional Fouriertransform is theBlassbeam-forming network illustrated byFig.8.26.TheBlassnetwork required N2 couplers forNinputs and Noutputs, whiletheconventional Fouriertransform alsorequires N2computations foranN-point transform. 
 HALF THAT OF A REAL APERTURE RADAR  2!2  OF THE SAME APERTURE DIAMETER #OURTESY OF 3CI4ECH 0UBLISHING  )NC  . £Ç°£ä  2!$!2 (!.$"//+  4HE SIDELOBES ARE ALSO DIFFERENT FOR 2!2 AND 3!2 &OR A 2!2 WITH AN UNWEIGHTED  APERTURE FUNCTION  THE TRANSMITTED INTENSITY AT THE PEAK OF THE FIRST ANGULAR SIDELOBE  IS REDUCED BY n D"  AND THE RECEIVED INTENSITY FROM A TARGET IN THAT DIRECTION IS THUS REDUCED BY n D" &OR A 3!2  TYPICALLY THE ENTIRE REGION OF THE IMAGE IS IN THE MAIN BEAM DURING THE DATA COLLECTION  AND THERE ARE NO EFFECTS FROM THE SIDELOBES OF THE PHYSICAL ANTENNA 4HE SIDELOBES RESULT SOLELY FROM THE PROCESSING  AND WITH NO WEIGHTING  THE FIRST SIDELOBE IS REDUCED BY n D" RELATIVE TO THE MAIN BEAM £Ç°xÊ 
 To verify the validity of this result under different radar frequencies, L-, S-, and X-band were also considered. ȱ (a)ȱ (b)ȱ Figure 13. (a) Normalized radar cross section (NRCS) contrast of eddy spirals Δσand ( b) NRCS contrast of SAR image Δσrunder different look directions and radar frequencies. 
 Theuseofdigitaldelaylinesrequires thattheoutputoftheMTIreceiver phase-detector bequantized intoasequence ofdigital words.Thecompactness andconvenience ofdigitalprocessing allowstheimplementation of morecomplex delay-line cancelers withfiltercharacteristics notpractical withanalog methods. Oneoftheadvantages ofatime-domain delay-line canceler ascompared tothemore conventional frequency-domain filteristhatasinglenetwork operates atallrangesanddoes notrequireaseparate filterforeachrangeresolution cell.Frequency-domain doppler filter­ banksareofinterestinsomeformsofMTIandpulse-doppler radar. Filtercharacteristics ofthedelay-line canceler. 
 #7 WAVEFORM  IS ROUGHLY EQUAL TO THE RATIO OF THE WAVEFORM BANDWIDTH TO THE WAVEFORM REPETITION FREQUENCY 4HE LOWER 
 WEIGHT CANCELER . 
 THESIZE A n ORIENTATION ANGLE FOR A LINEAR POLARIZATION TO EMPHASIZE THIS CLASS OR USE  VERTICAL POLARIZATION TO SUPPRESS THE DOMINANT CLASS IN THE IMAGE 6ARIOUS AUTHORS   HAVE SHOWN THAT ONE CAN SYNTHESIZE AN ELLIPTICAL POLARIZATION THAT INCREASES THE TARGET 
 The pulse duration  can he from 0.5 to 6.0 ps.  The VA-812C is a wideband UHF klystron with a 12 percent bandwidth. It is capable of  8 M W of peak power and 30 kW of average power, with a pulse width of 6 p. 
 ITY TO DIAGNOSE FAULTS AND FAILURES AS SOON AS THEY OCCUR .OT ONLY IS THIS NECESSARY  TO HASTEN THE REPAIR PROCEDURE  BUT ALSO IT ENABLES THE RADAR TO ADAPT ITS CONFIGURATION TO DO THE BEST IT CAN WITH IMPAIRED EQUIPMENT &OR EXAMPLE  IF THE RECEIVER CONNECTED TO THE MIDDLE ELEMENT IN AN ANTENNA ARRAY WERE TO FAIL  BEAMFORMING WOULD BE MORE SERI 
 Such clutter is more likely to he Rayleigh than sc,t clutter (Sec. 13.3) or land clutter  (Sec. 13.5) that often exhibit non-Rayleigh characteristics. 
 Anintensity-modulated rectangular displaywithazimuthangleindicated bythehorizontal coordinate andrangebytheverticalcoordinate. C-scope. Anintensity-modulated rectangular displaywithazimuthangleindicated bythehorizontal coordinate andelevation anglebytheverticalcoordinate. 
 TOR 4HE ABILITY OF A TRANSISTOR TO DEMONSTRATE HIGH POWER OUTPUT IS IMPACTED BY THE BREAKDOWN VOLTAGE  THE CURRENT CAPABILITY  AND THE KNEE VOLTAGE OF THE TRANSISTOR 3ILICON DEVICE TYPES COST 
 /N '&/   '&/  WAS DESIGNED TO REPLICATE AS MUCH AS POSSIBLE THE 'EOSAT EXACT 
 it is seldom employed since it cannot be readily achieved with practical antennas where  high gain and low sidelobes are desired. As the antenna size increases, the currents at the end  of the aperture become large compared with the currents along the rest of the aperture, and the  radiation pattern becomes sensitive to the edge excitation. This sets a practical upper limit to  the size of an antenna that can have a Dolph-Chebyshev pattern and therefore sets a lower  limit to the width of the main beam which can be achieved. 
 There is an out- put from the subtracter only when a reflection has occurred from a moving tar- get. Moving-Target Indicator (MTI) Block Diagram. A block diagram of a complete MTI system is shown in Fig. 
 OF 
 84. W. D. 
 K. Wu   et al.43) ch16.indd   39 12/19/07   4:56:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 (10.24) once p(ylSN) has  been evaluated. If the received waveform y(t) as a function of time consists of the signal  waveform si(t) plus the white gaussian noise waveform n(t) = y(t) -si(t), Woodward and  Davies27 show that  p(y I SN)= Pn[n(t)] = Pn[y(t) -si(t)] ex exp [-~~ J n2(t) dt I ( 10.25)  where Pn[n(t)] = probability-density function for noise waveform n(t) and N0 = mean noise  power per unit bandwidth (dimensions of energy). With this substitution, the a posteriori  probability for the signal si(t) becomes  { l To } p(SN I y) = kp(SN) exp -No ( [y(t) -si(t)]2 dt (10.26)  The integral in this expression is a definite one, with limits defined by the duration of the  observation time (0-. 
 The mean signal level varied very slowly burst  to burst since adjacent bursts covered essentially the same scene elements. The mean  signal level (AGC setting) was included in the header for each burst’s data record to  be used in subsequent SAR image formation.TABLE 18.7  Image Quality: Magellan Resolution and Looks Altitude (km)Incidence  (degrees) rR (m) rA (m) Looks NL QSAR NL/(rR rA)   250 52 110 122 4.8 3.6 ×10–4   500 39 137 121 6.0 3.6 ×10–4   1000 28 181 121 8.5 3.9 ×10–4   1750 21 247 120 11.6 3.9 ×10–4   2100 19 270 120 13.5 4.0 ×10–4 ch18.indd   51 12/19/07   5:15:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 White, “Polarization tracking of antennas,” presented at  IRE Int. Conv., Session 8, Antennas I, 1962. 39. 
 E. L. Allen, Jr.. 
 WAVE INTERACTIONS  REFLECTION PROCESSES  WAVE 
 B. A. Cahoon. 
 AVERAGED 
 Oulpul _.__.-.. / (0) (b) (c)\ /Figure11.17Threebasicformsof SAWinterdigital transducers for linearFMpulsecompression. (a) Dispersive delaylinewithdispersion designed intoonetransducer; (b) dispersion inbothtransducers. 
 Ponsford, L. Sevgi, and H. C. 
 Research on strong clutter suppression for Gaofen-3 dual-channel SAR /GMTI. Sensors 2018 ,18, 978. [ CrossRef ][PubMed ] 8. 
 Oceans 1994 ,99, 9785–9801. [ CrossRef ] 31. Gumming, I.G.; Wong, F.H. 
 A radar with a reflector  antenna designed to generate a cluster of many beams has been sometimes called a pincushion  radar.  In one example of a developmental radar that generated multiple beams, a spherical  transmitting antenna was surrounded by three spherical Luneburg-lens receiving antennas,  each covering a one-third sector of space.105 The transmitting antenna was a spherical phased  array of several thousand elements. with only a fraction of these energized at any one time to  form a directive beam. 
 FIELD PATTERN IS THE SUM OF THE VOLTAGE AMPLITUDE AND  PHASE  OF EACH RADIATING ELEMENT IN THE ANTENNA &OR THIS REASON  THE FAR 
 The  separation I is assumed to be less than cr/2, where c is the velocity of propagation and r is the  pulse duration. With this assumption, both scatterers are illuminated simultaneously by  the pulse packet. Another restriction placed on I is that it be small compared with the distance  R from radar to target. 
 12.2.3  Nonlinear Chirp Based on the Circle -φ Fun ction  Based on the "circle -φ" nonlinear chirp proposed by Price [8] the class of waveforms consi d- ered in this p aper have a frequency versus time characteristic given by the follo wing equation:   € f(t)=1 2BL⋅x+BC 2x 1−x2−1<x<1 where x=2t T−T 2<t<T 2 (12.1)  In these equations BL is the total sweep of the linear chirp component and Bc is the total fre- quency extent of a straight line which has the sa me slope as the circular term at x=0. An ex- ample of this type of non -linear chirp waveform is shown in Figure 12.20 for the sp ecific pa- rameters used later in this paper. The chirp duration is 100  µs with BL = 0.55 MHz and  Bc = 0.18 MHz, and the rise-  and fall- times are 1 µs. 
 Matijevic, “Back-scatter by  dielectric spheres (refractive index ~ 1.6),” IEEE Trans ., vol. AP-11, pp. 68−72, January 1963. 
 There is no need here to go deeply into the operational  uses of afterglow, but we can easily see that a steady  radar pattern—say, one resulting from a blip of a steady  response—will paint a nice, clearly defined picture on  the tube, whereas spasmodic, sudden bursts, such as  those caused by interference or unstable, spurious  echoes, will be fainter in comparison. The long, steady  echo has afterglow to help it, but the sudden, short  burst does not produce the same brilliance of afterglow.  On the other hand, a long-afterglow tube would tend to  paint a heavy picture from all responses, desired and  undesired, and after a fraction of a second the whole  tube surface might be quite blurred and unreadable. 
 The appearance of the three targets on an A-scope is  sketched in Fig. 2.26/J. The multiple-time-around echoes on the A-scope cannot be distin­ guished from proper target echoes actually within the maximum unambiguous range. 
 By using this structure, network can obviously improve its performance. 297. Sensors 2019 ,19,6 3   Figure 2. 
 Ê / 7HEN THE DOPPLER FREQUENCY OF THE RETURNS FROM CLUTTER IS UNKNOWN AT THE RADAR INPUT  SPECIAL TECHNIQUES ARE REQUIRED TO GUARANTEE SATISFACTORY CLUTTER SUPPRESSION !S DIS 
 12.11 cavity. This phase shift isdetected inthe phase-comparison tube VT byapplying theamplified crystal output tothecontrol grid and theaudio oscillator output tothesuppressor grid. Both grids arebiased tocutoff, sothat nocurrent flows inthetube unless thesignals areinphase. 
 J. Northey and P. S. 
 NULL OF ANTENNA PATTERN  OF A 3!2 IS ONE 
 24.14 24.9 Sky-Wave Transmission Medium  ...........................  24.15  24.10 Sky-Wave Radar Pe rformance  ...............................  24.22  24.11 Receiver-Pro cessor  ................................................ 
 For example, if the decorrelation time at X band were 10 ms, then it would be about  60 ms at L band, instead of the 70 to 75 ms predicted on the basis of a linear law. Therefore,  when the clutter spectra are given in units of velocity rather than frequency, the velocity  spectra arc slightly broader at the lower frequencies, an unexpected result.25 The spectra arc  broader for horizontal than for vertical polarization, and increase in width as the square root  of the wave height for both polarizations.  Observation time. 
 Compression is  achieved in the receiver by passing the s ignal through a  matched filter (see Figure 6). This filter is designed to have a  delay characteristic matched to the LFM frequency range, and  . www.tektronix.com/radar  7  delay s portions of the modulated signal proportional to the  carrier frequency. 
 Separate antennas fortransmitting andreceiving mightalsobeused.Theamountofisolation whichcan bereadilyachieved between thearmsofpractical hybridjunctions suchasthemagic-T,rat race,orshort-slot coupler isoftheorderof20to30dB.Insomeinstances, whenextreme precision isexercised, anisolation ofperhaps60dBormoremightbeachieved. Onelimitation ofthehybridjunction isthe6-dBlossinoverallperformance whichresultsfromtheinherent wasteofhalfthetransmitted powerandhalfthereceived signalpower.BoththeJossin performance andthedifficulty inobtaining largeisolations havelimitedtheapplication ofthe hybridjunction toshort-range radars. Ferriteisolation devicessuchasthecirculator donotsufferthe6-dBlossinherent inthe hybridjunction. 
 SYNTHETIC APERTURE RADAR  17 .296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 The geometry is more complicated but layover distance and object height may still  be estimated. Stereo SAR.  Two SAR images of the same scene may be obtained from somewhat  different locations (see Section 9.3.8.1 in Carrara et al.3). 
 E. Koch, “The value of wind profiler data in  U.S. weather forecasting,” Bull. 
 374 lNTRODUCTlON TO RADAR SYSTEMS  L 0% I 1 I I ] I I 1 I I 1 ll-T-T--I-l-T-] 1 11-1 -  aJ .- -  ' S/ng/e - tuned (RL C  resonont passband  0 1 .O 2.0 3.0 4 0 5 0  Holf-power bandwidth times pulsewidth, Br  Figure 10.2 Efficiency, relative to a matched filter, of a single-tuned resonant filter and a rectangular  shaped filter, when the input signal is a rectangular pulse of width r. B = filter bandwidth.  same as the signal s(t) for which the matched filter was designed (that is, the noise is assumed  negligible), the output would be the autocorrelation function. 
 Astrophys. J. 2016 ,833, 47. 
 POINT BY THE COMPLEX CONJUGATE OF THE REFERENCE &&4 OUTPUTS  AND THEN THE RESULT IS CONVERTED BACK TO THE TIME DOMAIN BY AN INVERSE &&4 )N GENERAL  IT IS MORE HARDWARE EFFICIENT TO PERFORM TIME 
 generator, asshown inFig. 16.12. The circuit works asfollows. 
 39. Laird, B. G.: On Ambiguity Resolution by Random Phase Processing, Preprints, 20th Conf. 
 3.1 as the receiver. The input signal is derived from the duplexer, which permits a single antenna to be shared between transmitter and receiver. Some radar antennas include low-noise amplifiers prior to forming the receive beams; although these are generally considered to be an- tenna rather than receiver elements, they will be discussed in this chapter. 
 THRESHOLD SYSTEM BY SETTING  A VERY HIGH THRESHOLD 5NFORTUNATELY  THIS WOULD REDUCE TARGET SENSITIVITY IN REGIONS OF LOW NOISE CLUTTER  RETURN 4HREE MAIN APPROACHESADAPTIVE THRESHOLD  NONPARAMET 
   4(% 2!$!2 42!.3-)44%2   £ä°ÓÎ !PPLICATION OF 'RID 
 vol. AP-22, pp. 582-584, July, 1974. 
 62, pp. 724-745, June, 1974.  74. 
   39.4(%4)# !0%2452% 2!$!2   £Ç°x PLATFORM PASSES BY THE TARGET  THE BEAM DIRECTION MOVES TO KEEP POINTING AT THE TARGET  )N THIS WAY   $P  MAY BE MADE CONSIDERABLY GREATER THAN  P"  AND CCR SPOTLIGHT     CCR  STRIPMAP  7E MAY WISH TO MAKE A CORRECTION FOR THE VARIATION IN RECEIVED POWER ^2   AS THE RANGE TO THE TARGET VARIES SLIGHTLY OVER THE SYNTHETIC APERTURE 4HIS IS  USUALLY NEGLIGIBLE FOR MOST SPOTLIGHT 3!2 APPLICATIONS BUT MIGHT NOT BE NEGLIGIBLE WHEN COLLECTION ANGLES ARE LARGE  SUCH AS FOR THE CASE OF FOLIAGE 
 &  OR  
  K(Z  
 The attenuation in the clear atmosphere, however, is  far worse than at millimeters and varies from about 10 dB/km at 1-mm wavelength to more  than lOOO dB/km at 0.1-mm wavelength.  Laser radar. The large attenuations experienced in clear air in the millimeter (60 GHz) and  submillimeter regions are not present in the infrared and visible regions of the spectrum . 
 Foggio: "Numerical Electromagnetic Code (NEC)—Method of Moments," Naval Ocean Systems Center, San Diego, 1981. 107. Pidgeon, V. 
 891-905, September, 1947.  38. Friichtenicht, H. 
 The sampling rate of the A/D 1s determined by the radar signal bandwidth, and the number of  bits is set by the dynamic range desired. Motion compensation for azimuth and range slip  (range walk) can be applied, as well as phase corrections for focusing. Semiconductor devices  are used for memory and arithmetic. 
 Girardet, and L. Bidart, “Mechanical and acoustic effects in low phase noise piezo - electric oscillators,” presented at IEEE, 43rd Annual Symposium on Frequency Control, 1989.  7. 
 Therefore it can all be lumped together and regarded as thermal noise. This is done, and the available-power level Pn is described by assigning to the noise a semifictitious "noise temperature" Tn, which is Tn = PnKkBn) (2.31) This is of course simply an inversion of Eq. (2.30), except that T in Eq. 
 WALL CROSS SECTION IS THE ! 
 Thesumanddifference signalsaremultiplied inaphase-sensitive detector toobtain boththemagnitude andthedirection oftheerrorsignal.Alltheinformation necessary to determine theangularerrorisobtained onthebasisofasinglepulse;hencethenamemmlO­ pulseisquiteappropriate. Amplitude-comparison monopulse. Theamplitude-comparison monopulse employs two overlapping antenna patterns (Fig.5.7a)toobtaintheangularerrorinonecoordinate. 
 MUM SIZE THE ANTENNA CAN BE FOR A PARTICULAR APPLICATION  THE NEED FOR A DESIRED RADAR RANGE  AND THE CHOICE OF RADAR FREQUENCY 4HE RADAR FREQUENCY IS USUALLY AFFECTED BY MANY THINGS  INCLUDING THE AVAILABILITY OF ALLOWED FREQUENCIES AT WHICH TO OPERATE 4HE RADAR FREQUENCY MIGHT BE THE LAST PARAMETER OF THE RADAR TO BE SELECTEDAFTER MANY OTHER COMPROMISES HAVE BEEN MADE. 
 This distance is equal to sin q. For this reason, a representation of this sort is  called sin q  space. A feature of sin q  space is that the antenna pattern shape is invariant FIGURE 13.7  Ten-element linear array scanned to 60 °; element spacing s = l /2 ch13.indd   15 12/17/07   2:39:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 SECTION AND RAINFALL MEASUREMENTS FROM  SPACE WITH A NADIR 
 When the matched filter is r e- placed with a combination of the 5- pole, 0.7 MHz Bessel filter and a phase -only matched fil- ter, the output shown in Figure 12.23 is obtained. While the  mismatch loss is slightly i ncreased  to 0.045 dB, the side lobe level beyond 4 µs from the peak is now below -50.9 dB. The inte- grated side lobe level outside ±4  µs from the peak is less than -41.8 dB. 
 The lower source inductance achieved with direct attachment to the metal flange of a  package base enables higher gains to be demonstrated for comparable Si BJT power  levels at frequencies below 2 GHz, but these devices are presently not attractive at  frequencies above S band. A primary advantage of the LDMOS device is thermal stability. The drain current  has a negative temperature coefficient; therefore, the LDMOS FET is not suscep - tible to thermal runaway and does not require the amount of gain-degrading resistive  emitter ballasting that is commonly required in a Si BJT to help normalize junction  temperatures. 
 In most cases of practical interest, the earth's surface and the medium in  which radar waves propagate can have a significant effect on radar performance. In some  instances the propagation factors might be important enough to overshadow all other factors  that contribute to abnormal radar performance. The effects of non-free-space propagation on  the radar are of three categories: (1) attenuation of the radar wave as it propagates through the  earth's atmosphere, (2) refraction of the radar wave by the earth's atmosphere, and (3) loht)  structure caused by interference between the direct wave from radar to target and the wave  which arrives at the target via reflection from the ground. 
 VARYING PARAMETERS  ADAPTIVE RADAR MANAGEMENT IS REQUIRED 2ADAR CROSS SECTION 2#3    R  4HE RADAR CROSS SECTION OF CONVENTIONAL TARGETS WILL  GENERALLY BE A FUNCTION OF FREQUENCY  POLARIZATION  AND ASPECT ANGLE  BUT AT (&  THE  TARGET DIMENSIONS ARE TYPICALLY OF THE SAME ORDER AS THE WAVELENGTH  SO SCATTER 
 Chan, “Passive radar using global system for  mobile communication signal: Theory, implementation and measurements,” IEE Proc.-Radar  Sonar Navig ., vol. 152, no. 3, June 2005. 
 3.54 Recommended Implemen tation  ..........................  3.54  4. Transmitters   ............................................................ 
    WHERE  . IS THE NUM 
 This arrangement of rotatable resonant rings was similar to the method used in the attenuator to divide power between the scanner and the dummyload. In the manual position, scanning was the same as on ASV Mk. III and ASV Mk. 
 The subsequent rapid development of ASV radars following the outbreak of war is described in the chapters following. 1.5 Outline of the book Chapter 2describes the ﬁrst ASV radars, ASV Mks. I and II, operating at a wavelength of 1.5 m. 
 TION CHANGE VENTILATOR LOCATIONS DONT CHANGE   AND CONSISTENT TRAJECTORY EG   MPH WHERE THERE ARE NO ROADS IS IMPROBABLE FOR A SURFACE VEHICLE   )N ADDITION  VEHICLES OF  INTEREST MAY HAVE RELATIVELY LOW RADIAL VELOCITIES REQUIRING ENDOCLUTTER PROCESSING IE   FAR ENOUGH INSIDE MAIN 
 AP-6, pp. 380-384, October, 1958.  100. 
 PATTERN PEAK TO THE ERROR 
 Iftheantenna isnotstabilized, itspencil beam will atsome instant bedirected toward Abelow thehorizon. The indicator will then show anangle measured bythearcHA.Ifthe beam isstabi- lized byatwo-axis mount, itwill atthat instant beatthepoint Bwhere the great circle AMintersects the horizon; since HBexceeds HAthe indicator will report the position ofthe beam falsely. Ifthe beam is stabilized byathree-axis mount, itwill bedirected toward C;theindica- tion isagain false since HCisless than HA.Thus either ofthese types ofstabilization results inadistortion ofthe bearing oftargets onthe horizon. 
 Snow Similar to the effects of hail, the overall effect of clutter on the picture is less than that due to rain. Falling snow will only be observed on the displaysof3cmexceptduringheavysnowfallwhereattenuationcanbeobservedona10cm set. The strength of echoes from snow depends upon the size of the snowﬂake and the rate of precipitation. 
 !n 
 M. Richards, Fundamentals of Radar Signal Processing , New York: McGraw-Hill, 2005. 25. 
 ERATELY HARD 
 The small glass reflectors usedin highway markers work onthis principle. Acorner reflector consists ofthree mutually perpendicular intersecting planes (Fig. 3.2cL). 
 The Ideal Observer applies equal weight to an error due to a false alarm and to an error  due to a miss. However, there may be cases in which equal weight is not appropriate (Bayes  criterion). If the errors are not of equal importance, the theory of the Ideal Observer may be  modified to take this into account using the concepts of statistical decision theory.24•32-34  Unfortunately, in most radar applications there is no realistic basis for assigning a value to a  miss or to a false alarm; consequently, the usefulness of decision theory in radar is limited. 
 38. pp. 53-59, January, 1950. 
    $F  S 4HE  PHASE AND AMPLITUDE OF EACH PULSE ECHO IS DIGITALLY RECORDED BY THE RADAR !S SHOWN IN &IGURE  A  A DISCRETE &OURIER TRANSFORM $&4 TYPICALLY A FAST 
 The method allows freedom inthe choice ofline constants and ofelectrical coupling, with some resultant circuit simplifica- tion ascompared with thethree-crystal delay line. However, theamount ofthermal correction isnot asgreat asinthe three-crystal line, The. SEC. 
 FREQUENCYv PULSE OF WAVELENGTH  K  THE DIFFERENCE IN THE PHASES OF THE ECHOES  RECEIVED FROM THE POINT TARGET OBSERVED BY THE TWO ANTENNAS IS FROM &IGURE     $FP LPY L   NSN,SIN    7 E NOW CONSIDER THE SAME ANTENNAS  ! AND " OBSERVING A SECOND POINT TARGET  B THAT  IS A DISTANCE  H ABOVE THE FLAT GROUND ALSO AT RANGE  2 THE RADAR LINE 
 (ILL   CHAP   P   ! 7 2IHACZEK  h2ADAR SIGNAL DESIGN FOR TARGET RESOLUTION v  0ROC )%%%  VOL   PP n   &EBRUARY   ! ) 3INSKY AND # 0 7ANG  h3TANDARDIZATION OF THE DEFINITION OF THE AMBIGUITY FUNCTION v  )%%%  4RANS !EROSPACE AND %LECTRONIC 3YSTEMS  PP n  *ULY   )%%% STANDARD RADAR DEFINITIONS  )%%% 3TD  
 TAP &)2 FILTER. 
 November, 1954. n.Andreasen, M.G.:Back-scattering CrossSectionofaThin,Dielectric, Spherical Shell,IRETrans., vol.AP-5,pp.267-270. July,1957. 
 LAR  THE ,$-/3 STRUCTURE ENABLES A SHORT CHANNEL AS A RESULT OF THE LATERAL DIFFUSION OF THE P 
 64. S. G. 
 1One ofthefeatures ofthis system was exact control ofthenightfighter, prior tohisinterception ofthehostile bomber, byaground controller ataGCI (for Ground-controlled Inter- ception) radar station. The aim ofthis control was toput the night- fighter behind, alittle below, and onthe same course asthe hostile aircraft, inwhich position hewas well situated tocomplete the inter- ception ~vith thehelp ofairborne radar equipment hehimself carried. By1943, both this GCI technique, involving precise control ofsingle aircraft byacontroller located ataradar station, and thedaytime sector- control technique described inSec. 
 The output of the  delay line is a signal of frequency .fc with a phase shirt <J, = 2nfc r. This phase-shifted signal and  the output of the first mixer are then heterodyned in the second mixer. If the sum frequency is  selected from the first mixer, the difference frequency is selected from the second mixer. 
 Taylor, J. W., Jr., and J. Mattern: Receivers, chap. 
 In a specific example presented in Farina and Timmoneri,73 two carrier  frequencies are used and the values of d/l (where “ d” is the inter-element distance)  for the array of receiving elements are respectively 0.5 and 0.55. The blanking is  separately applied on the received data at the two carrier frequencies; subsequently,  the separate blanking bits are processed by a logic OR (the global blanking logic).  The ensuing Figure 24.5 displays the blanking curves for the two separate carrier  frequencies and for the logic OR. 
 BEAM CLUTTER CAN BE MINIMIZED BY NARROW DOPPLER ANDOR RANGE BINS IE  RESOLUTION CELLS   WHICH IMPLY LONGER DWELL TIMES AND HIGHER TRANSMIT BANDWIDTH /NE EXAMPLE METHOD FOR SELECTING A SET OF 02&S FOR -02& IS GIVEN IN %Q  4HE  BASIC IDEA IS TO FIND A TIME INTERVAL  4 !  REPRESENTING THE DESIRED MAXIMUM CLEAR RANGE   AND THEN TO CHOOSE A SET OF 02)S IN WHICH ALL WILL BE CLEAR AT MAXIMUM RANGE 4HIS CAN BE ACHIEVED BY DIVIDING  4 ! BY AN INTEGER  TYPICALLY  TO  4HIS SET WILL GENERALLY NOT  PROVIDE  CLEAR OVER THE RANGE 
 6X.Buynen. J.R.:TheoryandDesignofaClassofLuneburg Lenses,IREWESCON CO/II'.Record. vol.2.pI.1,PI'.219230.1958. 
 As noted in Billingsley9 all three  models are in reasonable agreement for the upper 30–40 dB of their range but differ  appreciably at the lower values of clutter spectral density. Estimated values of the spectral spread of land clutter from forested regions and  for different wind speeds are shown in Table 2.1. The values in the table are based  on Billingsley’s parameter b , but columns have been added with the corresponding  rms spectral spread in m/s. 
 Dynamic range is usually defined as the ratio of the  maximum signal that can be handled to the smallest signal capable of being detected. The  smallest signal is the minimum detectable signal as determined by receiver noise, and  the maximum signal is that which causes a specified degree of intermodulation or a specified  deviation from linearity (usually 1 dB) of the output-vs.-input curve.  When an RF amplifier is inserted ahead of the mixer stage, and if no change is made in the  remainder of the receiver, the minimum signal will be reduced because of the lower noise  figure of the RF amplifier, but the maximum signal that can be handled by the receiver will  also be reduced by an amount equal to the gain of the amplifier. 
 BAND ANTENNA SCANS MECHANICALLY OVER  n IN AZIMUTH  AND SCANS ELEC 
 The equivalent can be accomplished in the digital computations.  Ttie generation by digital processing of N filters from the outputs of N taps of a transver-  sit1 filtcr requires n total of (N - multiplications. Tlie process is equivalent to the cornputa-  t ioil ol' it (lisc.r.(~~c I.'crirr.ic~t. 
 Kock. W. E.: Path-length Microwave Lenses, Proc. 
 If, on the other  hand, low-altitude coverage is to be optimized within the interference region and if there is no  concern for coverage beyond the horizon, the radar frequency should be as high as possible.  (This assumes the absence ofducting.)  The formula for the distance along the line of sight [Eq. ( 12.14 )] should not be used as a  measure of the radar coverage without some reservation. 
 FIELD RADIATION  NORMAL SPACECRAFT DESIGN PRINCIPLES KICK  IN 4HE FIRST ORDER CON 
 Turning off the receiver during transmission  with a duplexer is not possible in a CW radar since the transmitter is operated continuously.  Isolation between transmitter and receiver might be obtained with a single antenna by using a  hybrid junction, circulator, turnstile junction, or with separate polarizations. Separate  antennas for transmitting and receiving might also be used. 
 SECOND CONSTANT UPDATE INTERVAL 4HE APPLICATION OF THIS RADAR SYSTEM IS TO TRACK A TARGET THAT MOVES LINEARLY BUT WITH OCCASIONAL UNPREDICTABLE MANEUVERS OF UP TO  G  MS    %RROR 3OURCE3TEADY 
 9, October-December 1946. 46. Cummings, R. 
 M.. K. S. 
 The  average cross section of small pleasure boats 20 to 30 ft in length might have a radar cross i  section in the vicinity of a few square meters at X band.68 Boats from 40 to 50 ft in lc~lgrll  might have a cross section of the order of 10 square meters.  The radar cross section of an automobile at X band is generally greater than that of an  aircraft or a boat. From the front the cross section might vary from 10 to 200 mZ at A' band,  with 100 mZ being a typical value.65 The cross section increases with increasing frequency (up  to 60 GHz, the range of the measurements). 
 BAND DATA AT A  GRAZING ANGLE FOR LOW  MEDIUM  AND HIGH WIND SPEEDS IN ORDER FROM LEFT TO RIGHT  4HE LOW 
 However, a  simple spherical reflector does not produce an equiphase radiation pattern (plane wave), and the  pattern is generally poor. The term splterical aherratiort is used to describe the fact that the  ~'lt:t~c frotlt of tlic wave radiated hy :I splierical reflector is not plane as it is with a wave  ~adiittcd hy 311 idcltl parabolic rcllcctor. 'l'llerc arc at least tllrce tech~liques w11icl1 rlligllt bc  used to miriimi7e tile effect of spherical aberration. 
  
 The purpose of the detector is to convert the bipolar video to unipolar video. Tf~c  output of the integrator is applied to a threshold-detection circuit. Only those signals which  cross the threshold are reported as targets. 
 TANCES SIMULTANEOUSLY  AND MINIMIZE A METRIC SUCH AS THE SUM OF ALL STATISTICAL  DISTANCES FOR A COMPLETE ASSIGNMENT SOLUTION 0ERFORMING THIS OPTIMIZATION CAN BE DONE USING -UNKRES ALGORITHM  -UNKRES ALGORITHM IS AN EXACT SOLUTION OF  THE MINIMIZATION PROBLEM BUT IS RARELY USED BECAUSE IT IS COMPUTATIONALLY SLOW ! MORE COMPUTATIONALLY EFFICIENT EXACT SOLUTION IS THE *ONKER  6OLGENANT  #ASTANON *6#  ALGORITHM  4HE *6# IS MUCH MORE EFFICIENT FOR SPARSE ASSIGNMENT MATRICES  WHICH ARE LIKELY FOR PRACTICAL RADAR 
 The primary pattern of the feed illt1minating  the space-fed array provides a natural amplitude taper. Spillover radiation from the feed,  however, can result in higher sidelobes than from an array with a conventional constrained  feed. The space-fed array can readily generate a cluster of multiple beams, as for monopulst.:  angle measurement, by use of multiple horns or a multimode feed, rather than with a com­ plicated feed network as in the conventional array. 
 Repeater "Calseechoes" canbeunmasked assuchby utilizing inanunpredictable mannerdifferent pulserepetition frequencies, rffrequencies, pulse widths,internal pulsemodulations, orpolarizations. Sidelobe blankers canprevent repeater signalsfromentering theradarviatheantenna sidelohes andappearing onthedisplay in directions different fromthatofthejammer. Inatracking radar,circuitry canheLkvised to prevent range-gate stealersfromcapturing therangegate.Monopulse tracking radarcanhe employed toavoidthevulnerability ofconical-scan tracking radarstomodulations thatcause ittobreaklockinangle. 
 F. C. Lin and F. 
 , 
 BASED SYSTEMS  SUCH AS DOPPLER NAVIGATORS  MOVING 
  
 An optional capability of AREPS is to provide to an external application, the com - puted radar probability of detection, propagation loss, or propagation factor, to an exter - nal application. Thus, a tactical application developer need not have knowledge of the  underlying radar propagation modeling techniques or other environmental consider - ations but can rely upon AREPS to “serve up” data for display within his or her own  application. Such an application is the Simulation and Display System (SIMDIS™),  authored by the Naval Research Laboratory, Washington DC.27 Figure 26.12 is an illus - tration of AREPS-computed data displayed three-dimensionally within SIMDIS™. 
 VIDES SOME USEFUL INSIGHTS  4HE PLATFORM  IE  VEHICLE  OR INSTALLATION SITE IS A SIGNIFI CANT DRIVER FOR RADAR SEN 
 The second method, rinle slicir~g, breaks all lower-priority  tasks into nor~preemptable segments. These segments must be short enough to avoid excessive  delays in the transfer of control to the time-critical tasks.  The phased-array radar and its computer controller saturate differently. 
 In this configuration, the long-term  stability of the reference oscillator is superior to that of the radar oscillator, and the  short-term stability of the radar oscillator is superior to that of the reference oscillator.  The phase lock loop (PLL) architecture is established to exploit the strengths of both  technologies by selecting a PLL bandwidth at the offset frequency where the source  stabilities cross over. For typical radar and reference oscillator technologies, this usu - ally occurs in the 100 Hz to 1 kHz offset region. 
 TARGET SEQUENCE PASS 
 RANGE DIMENSION TO  BE OBTAINED )T CAN BE ON A MOVING VEHICLE OR IT CAN BE STATIONARY 7EAPON CONTROL RADAR 4HIS NAME IS USUALLY APPLIED TO A SINGLE 
 The remainder ofthe saw- tooth istherefore amplified and, bysuitable overdriving and clipping, can beturned into arectangular wave. The transmitter trigger isthen derived from thefront edge ofthis rectangular wave, and thewave itself serves tointensify the cathode-ray tube. Ifasimple sawtooth isused, themaximum useful sweep duration has anupper limit ofhalf the pulse period; somewhat less can berealized in inadequate high-frequency response inthesynchro and amplifiers, andfrom crosa- coupling intheformer, were troublesome only onfast sweeps. 
 Teague, “Calibration of HF radar systems with ships of  opportunity,” Proc. of the 2003 IEEE Int. Geoscience and Remote Sensing Symp ., New York,  July 2003, pp. 
 Thustheparameter ofaperture efficiency, whic~sometimes isheldsacredbytheantenna designer andtosomewhowriteantenna specifications, isoftenofsecondary importance tothe systems engineer wishing tooptimize totalradarperformance. Itcanusuallybetradedfor somemoreimportant characteristic. 7.2ANTENNA RADIATION PAITERN ANDAPERTURE DISTRIBUTION Theelectric-field intensity E(cP)p'roctucedbytheradiation emitted fromtheantenna isa function oftheamplitude andthephaseofthecurrentdistribution acrosstheaperture. 
 The greater the duration of the spike,  the greater the size and duration of the whitecap. A spike echo can appear without the  presence of a whitecap, but no whitecap is observed in the absence of a spike. The spike echo  at X band is amplitude modulated with frequencies of the order of 50 Hz and with a high  modulation index. 
 2ANGE #HARACTERISTICS.   2!$!2 2%#%)6%23   È° È°ÎÊ    7 /Ê " - 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar.  CIVIL MARINE RADAR  22.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 marine radar today. 
 H. Stiles. L. 
 55. R. Nitzberg, Adaptive Signal Processing for Radar , Norwood, MA: Artech House, Inc., 1992. 
 BEAM TUBES IS THE TYPE OF MICROWAVE CIRCUIT EMPLOYED .   4(% 2!$!2 42!.3-)44%2   £ä°x AND THE NATURE OF THE INTERACTION THAT PRODUCES AMPLIFICATION 4RANSIT 
 The value of a2 for a perfectly rectangular pulse of width T is n2r2/3; thus the rms  frequency error is  JJ a/= -- rectangular pulse  ~T(~E/N~)~~~  The longer the pulse width, the better the accuracy of the frequency measurement.  EXIHACI\ON OFINFORMATION ANIJWAVEFORM DESIGN 407 whereristhehalf-powerpulscwidth:-The' gaussian-shaped pulseissumetimes specified in thoseapplications whereinterference withequipments operating atllearby frequencies istobe avoided. Thegaussian pulseiswellsuitedforthispurpose sinceitsspectrum decaysrapidlyon eithersideofthecarrierfrequency. 
 The shape of the  anthropogenic curves is described by the equations  No = – 136 – 12.6 ln ( f /3) residential   No = – 148 – 12.6 ln ( f /3) rural   No = – 164 – 12.6 ln ( f /3) remote (20.12) where the frequency f is in megahertz and ln indicates the natural logarithm. These frequency trends approximate many measurements of human-made noise  but ideally the curve would be based on measurements at the particular radar site. The  galactic-noise curve should be selected when it is the largest and when there is a path  through the ionosphere; the path will not exist for the lower operating frequencies in  the daytime. 
  
 However, in prac-  tice it is seldom required that a radar generate more than a few simultaneous beams (perhaps  no more than a dozen), since the complexity of the array radar increases with increasing  number of beams.  Although the array has the potential for radiating large power, it is seldom that an array is  required to radiate more power than can be radiated by other antenna types or to litilizr: a  total power which cannot possibly be generated by current high-power microwave tube tech-  nology that feeds a single transnlission line.  Conventional microwave antenn.as cannot generate radiation patterns with sidelobes as  low as can be obtained by an array antenna, especially a nonscanning array. 
   3%! #,544%2  £x°£Î WAVE SPECTRUM CONSIDERATIONS )T IS POSSIBLE TO FIND EXAMPLES OF DATA THAT APPEAR  TO FOLLOW SUCH BEHAVIOR WHILE AT THE SAME TIME BEING EXPRESSED AS A POWER LAW BY  BRUTE LINEAR REGRESSION  AS ILLUSTRATED IN THE TOWER DATA SHOWN IN &IGURE  4HIS  BEHAVIOR IS NOT UNCOMMON &)'52%    ! HYPOTHETICAL WIND 
 SIN   COS  VVV     66!EE! E!3JT JT 2JT 3 )&#/(/ 
 BAND OPERATION PROVIDES THE EXPECTED MICROWAVE PERFORMANCE OF  GOOD RADAR RANGE  AND PRECISE TRACKING )TS WEAKNESS IS THE LOW 
 Thefrequency oftheamplitude-limited beatnoteismeasured witha cycle-counting frequency metercalibrated indistance. Intheabove,thetargetwasassumed tobestationary. Ifthisassumption isnotapplicable, adoppler frequency shiftwillbe'superimposed ontheFMrangebeatnoteandanerroneous rangemeasurement results.Thedoppler frequency shiftcausesthefrequency-time plotofthe echosignaltobeshiftedupordown(Fig.3.12a).Ononeportionofthefrequency-modulation cycle.theheatfrequency (Fig,3.12b)isincreased bythedoppler shift,whileontheother portion. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 than on the real axis of the Z-plane. 
 FICIENT STORAGE AND COMPUTING TO ALLOW BEAM REPOINTINGADJUSTMENT IN A FRACTION OF  MSEC &AST BEAM ADJUSTMENT REQUIRES HIGH 
 CARRYING CAPACITY  STRING SUSPENSION TECHNIQUES ARE BEST SUITED FOR MEASUREMENTS OF LIGHT OBJECTS AT LOW FREQUENCIES 4HE METAL TARGET SUPPORT PYLON WAS FIRST SUGGESTED IN    BUT A PRACTICAL IMPLE 
 Another possible configuration providing  multiple broadband beams uses parallel plates containing a wide-angle microwave  lens.35,36  Each port corresponds to a separate beam. The lens provides appropriate  time delays to the aperture, giving frequency-invariant scanning. The beams may  be selected through a switching matrix requiring M − 1 single-pole–double-throw  (SPDT) switches to select one out of M beams. 
 10.11 10.11. Miscellaneous Components. PulseTransformers.—The devel- opment ofpulse switching tubes and ofpulse loads has proceeded so independently that usually there islittle correlation between theoptimum impedance levels forbest operation ofthese two devices. 
 N.·: "Radar System Engineering," MIT Radiation Laboratory Series, vol. I, chap. 16,  McGraw-Hill Book Co., New York, 1947. 
 The spectrum of atmospheric noise falls  of rapidly with increasing frequency and is usually of little consequence above 50 MHzs4  Hence atmospheric noise is seldom an important consideration in radar design, except, per-  haps, for tadars in the lower VHF region.  Another source of noise predominant at the lower radar frequencies is urban noise, also  known as man-made noise. Noise from automobile ignition, electric razors, power tools, and  fluorescent lights are examples. 
 When low-noise amplifiers (LNAs) are included in the antenna, prior to forming  the receive beams, the antenna sidelobe levels achieved are dependent upon the degree  to which gain and phase characteristics are similar in all LNAs. Dynamic range has  an exaggerated importance in such configurations because matching nonlinear char - acteristics is impractical. The effect of strong interference—mountain clutter, other  radar pulses, or electronic countermeasures (ECM)—entering through the sidelobes  will be exaggerated if it exceeds the dynamic range of the LNAs because sidelobes  will be degraded. 
 ARRAY 4HE SECOND  CONFIGURATION IS IRREGULAR WITH           AND  ELEMENTS  RESPECTIVELY &IGURE  SHOWS THE 3).2 AT THE OUTPUT OF THE ARRAY VERSUS THE JAMMER $O! 4HE TARGET $O! IS AT   THE 3.2 IS  D"  THE *.2 IS  D" 4HREE CURVES SUMMARIZE THE SYSTEM PERFORMANCE 4HE DASHED LINE IS THE ARRAY PATTERN WITH RAISED COSINE TAPER THIS IS SHOWN FOR THE SAKE OF COMPARISON WITH THE OTHER TWO CURVES OF THE 3).2 4HE DOT 
 (Note  that the direction of VT cos(yT) is assumed to be the opposite of VR cos(y0) resulting in  a relative range rate of Vrelative  = −VT cos(yT) − VR cos(y0), which is consistent with the  definition for doppler shift stated at the beginning of the chapter .) Figure 4.3 illustrates the various clutter doppler frequency regions as a function  of the antenna main-beam azimuth and relative radar and target velocities, again  for an unfolded spectrum. The ordinate is the radial or line-of-sight component of  target velocity in units of radar platform velocity, so the main-beam clutter region  is at zero velocity and the sidelobe clutter region frequency boundaries vary sinu - soidally with antenna azimuth. Thus, the figure shows the doppler regions in which  the target becomes clear of sidelobe clutter. 
 connected to the two  ports of a 3-dB directional coupler as shown in Fig. 8.27. If a signal is inserted in port No. 
 10.2).  A liriiitation of ttie rnethod of inverse probability based on the application of Bayes' rule is  the difficulty of specifying the a priori probabilities. In most cases of practical interest, one is  ignorant of the a priori probabilities. 
 It is  ofteri possible to reduce the wind torques by selecting the optimum position for tlie axis of  rotatioil and by adding fins to the structure.' l4 The torque on the fins can be made to be in the  opposite direction to tlie torque on the antenna so as to cause a net reduction.  One of tlie attractions of the rigid radome is its ability to withstand the rigors of severe  climate. Kitlie ice, tlic prevale~it type of icing found in the Arctic region, has little or no effect  on most radomes. 
 17.14, separating thevarious signals and providing asimulated scanner motion. The separation ofvideo signals from pulses isaided byanamplitude selector which takes advantage ofthehigher power inthepulses. This is helpful, especially during the locking-in period. 
 21, pp. 59 63. biarch. 
 Ifasuitable deviceisuscdtomeasure /10,atargetsignalissaidtobepresentifthisnumber is lessthanapredetermined (threshold) valueandissaidtobeabsentifthethreshold is cxccedcd, (Thevalucof/10isamaximum whenSIN=0.) Coherent detector. Thecoherent detector (Fig.10.4)consistsofareference oscillator feedinga balanced mixer.Theinputtothemixerisasignalofknownfrequency foandknownphase¢o plusitsaccompanying noise.Thereference-oscillator signalisassumed tohavethesame frequency andphaseastheinputsignaltobedetected. Theoutputofthemixerisfollowed bya low-pass filterwhichallowsonlythed-candthelow-frequency modulation components to passwhjlerejecting thehigherfrequencies inthevicinityofthecarrier.Thecoherent detector provides atranslation ofthecarrierfrequency todirectcurrent.Itdoesnotextractthe modulationenvelope andisatrulylineardetector, whereasthe"linear"envelope detector was notlinearinthesamesense.Therefore thecoherent detector willbeamoreefficient detector, especially whensignal-to-noise ratiosarelow. 
 Consequently, a one-dimensional linear rheological model, the Kelvin model, was selected for our experiments. The Kelvin rheological model is a kind of commonly used delay model, based on mechanical composition elements. It is a parallel system with a spring (pure elastomer) and a glue pot (pure viscous body), illustrating the phenomenon that, under the action of stress, the strain of the material does not reach the ﬁnal strain value immediately, but has a relative lag process. 
 ALTITUDE COVERAGE $ETECTION OF MOVING TARGETS IN CLUTTER IS OFTEN BETTER AT THE LOWER FREQUENCIES WHEN THE RADAR TAKES ADVANTAGE OF THE DOPPLER FREQUENCY SHIFT BECAUSE DOPPLER AMBIGUITIES THAT CAUSE BLIND SPEEDS  ARE FAR FEWER   AT LOW FREQUENCIES 6(& RADARS ARE NOT BOTHERED BY ECHOES FROM  RAIN  BUT THEY CAN BE  AFFECTED BY MULTIPLE 
 ARRIVAL TO GEOGRAPHI 
 AVG 4X 
 FACE BEAM STEERING IN A PHASED ARRAY ANTENNA !RCHITECTURE VARI ATIONS MAY RESULT  FROM COMPONENT CAPABILITY DIFFERENCES AS WELL AS PERFORMANCE AND PACKAGING CONSTRAINTS . ££°ÓÈ  2!$!2 (!.$"//+  0OWER !MPLIFIERS    4HE AREA CONSUMED BY COMBINING IN PARALLEL THE TOTAL NUM 
 When the periodic waveform is truncated to one complete sequence, this constant sidelobe property is de- stroyed. For large N the peak-sidelobe-voltage ratio is approximately AT"172 for the aperiodic case. Maximal-length sequences have characteristics which approach the three ran- domness characteristics ascribed to truly random sequences,27 namely, that (1) the number of Is is approximately equal to the number of Os; (2) runs of consecutive Is and Os occur with about half of the runs having a length of 1, a quarter of length 2, an eighth of length 3, etc.; and (3) the autocorrelation function is thumbtack in nature, i.e., peaked at the center and approaching zero elsewhere. 
 66. G. S. 
 OF 
 15.3. This block diagram represents an MTI system that uses a pulsed oscillator. It is not as sophisticated as MTI systems to be described later, but most of the practical considerations applying to any MTI system can be understood by examining this block diagram. 
 The conversion loss is less in the narrowband than in the broadband mixer. In  principle, it can be about 2 dB lower.6 The design of a broadband mixer has been simpler to  achieve arid less critical than a narrowband mixer.  'i't~e rloise-terrtperature ratio of a crystal mixer (not to be confused with effective noise  tenlperature) is defined as  actual available IF noise power  t, = - - - - - - -- -  available noise power from an equivalent resistance (9.12a)  where I;, = crystal mixer noise figure and LC = 1/G, = conversion loss. 
   AND 2! 
 WAY PROPAGATION LOSS OF ITS ENERGY AS CONTRASTED WITH THE ONE 
 The FIR impulse response of the  combin ation of the reciprocal ripp le filter and the phase -only Matched filter as described  above is shown in Figure  12.28 (gray curve) together with a version of this filter, which has  been truncated to a total of 337 taps corresponding to a total r esponse time of 135 µs. This only  exceeds the Matched filter implementation (250 taps) by 35%. The co mpressed output resul t- ing from the use of this truncated filter is shown in Figure  12.29. 
     . 
 !" )N PRACTICE  THEY CAN BE MADE TO BE hSELF 
 nT ‘1>A bT4 (a) (b) FIG.13.25 .—Two-waY clamps. (a) Two-way double-triode clamp; (b) two-way four-diode clamp. clamps, and Fig. 
 The colour  depends on the chemical nature of the screen, and zinc  silicate (Willemite) is a commonly used material, giving  a bright-green spot. The chemical fluoresces when the  electron beam touches it, and, of course, there is no  connexion between the natural colour of the powder  applied to the end of the tube and the colour it exhibits  when under fluorescence; most of the screens are  whitish in colour, viewed in natural light, but they  fluoresce only according to the chemical structure. The  electron beam ‘lights up’ the substance, and not un-~  naturally this fluorescence takes some time to die away;  there is a natural tendency for it to continue glowing  for a minute period of time after the electron pencil has  moved on. 
 Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft.  MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.456x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 59. E. 
 Elachi, Radar Polarimetry for Geoscience Applications . Boston: Artech  House, 1990. ch16.indd   62 12/19/07   4:56:50 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Journal Electronics and Communications  (AEÜ), vol. 53, no. 6, pp. 
 Ridenour, L.N. Radar System Engineering ; McGraw-Hill Book Co.: New York, NY, USA, 1945. 2. 
 STATE MODULE . 
 Image registration of SAR and optical image based on feature points. In Proceedings of the IET International Radar Conference 2013, Xi’an, China, 14–16 April 2013; pp. 1–5. 
 )(. ) . λ λ λ  For the same amount of grating-lobe suppression, the square geometry requires  approximately 16% more elements. 
 Skolnik, Introduction to Radar Systems , 2nd Ed., New York: McGraw-Hill Book   Company, 1980. 22. D. 
 FREQUENCY 2#3 PREDICTION TECHNIQUES v  0ROC )%%%  VOL    PP n  &EBRUARY   % & +NOTT ET AL  2EF   P  % & +NOTT ET AL  2EF   PP n 4 " ! 3ENIOR  h! SURVEY OF ANALYTICAL TECHNIQUES FOR CROSS 
 GET AND THAT THE PHASE DEVIATION BE LESS THAN  )T IS STANDARD PRACTICE AT SOME TEST RANGES TO PHYSICALLY PROBE THE INCIDENT FIELD AT THE ONSET OF A TEST PROGRAM TO VERIFY THE AMPLITUDE UNIFORMITY OF THE INCIDENT WAVE 4HE PHASE REQUIREMENT IS THE BASIS OF THE FAR 
 BEAM MONOPULSE TRACKING RADAR v  )%%%  4RANS  VOL !%3 
 Thus, the PRF is equal to the Doppler bandwidth of a single beam. At the same time, there is no restriction on the direction of the beam, and the required beam pointing can be set. When the scattering angles vary from 20◦to−20◦, the results of the imaging will be different [ 3]. 
 Unequal spacings have sometimes been considered in order to obtain a given beam­ width with considerably fewer elements than an equally spaced array, or to approximate a  desired pattern without the need for an amplitude-tapered aperture illumination. Since the  minimum element spacing is about one-half wavelength, unequally spaced arrays generally  have fewer elements than equally spaced arrays of the same size aperture. For this reason they  are also called thinned arrays. 
 Increasing tlic antcnna height incrcrtscd tlie loss to a maximum at about 10 m  height. Further increase of I~eight decreased the attcnuation until a secondary minimi~m was  obtained at 20 m height, after which the attciiuation again increased (at least to a liciglit of  30 m). On a ship it might not be practical to site a radar antenna 2 m over the sea. 
 Sincelonglifeisafeatured characteristic ofsuchpowersources, theyshouldbeoperated conservat ively.) Thepoweroutputofamicrowave transistor theoretically decreases inversely asthe squareofthefrequency, or6dBperoctave.29Forthisreasonthesiliconbipolartransistor is unattractive forradarapplication atSbandorabove,especially whenappreciable poweris desired. Varactor frequency multipliers, however, generally" haveattenuation lessthantheir frequency-multiplication ratiosothatatransistor atsomelowerfrequency followed bya varactor multiplier hassometimes beenemployed toobtainpoweratthehighermicrowave frequencies. Inoneexperimentaldesign,30 X-band powerwasobtained byanS-bandtransistor followed byafour-times multiplier toobtain1wattofpeakpoweratXbandwitha0.05duty cycle. 
 Clutter Offset Generator.  The clutter offset generator shifts the transmit carrier  slightly, so that on receive the main-beam clutter is positioned at zero doppler fre - quency, or DC (direct current) after basebanding. The same effect could be obtained  by shifting the receiver LO1 frequency. 
 C. J.: High Resolution Land Cluller Characteristics, IEE Conf. Pub!. 
 FOURTH AND THREE 
 Iranunknown doppler-frequency shiftisexperienced whenalong pulse,anoise-modulated pulse,orapulsetrainisreflected fromamoving target,areceiver tunedtothetransmitted signalwillnotaccepttheechosignalifthedoppler shiftplacesthe echofrequency outsidethebandofthereceiver matched filter.Thatis,thereceiver maynotbe tunedtothecorrectfrequency. Tocircumvent thispotential lossofsignal,abankofcontig­ uousmatched filtersmustheusedtocovertherangeofexpected doppler-frequency shifts.It ispossible, however, withasuitable transmitted waveform toemploy asinglematched filter thatwillacceptdoppler-shifted echoeswithminimum degradation. Ithasbeenshownthatthewaveform whichallowsasinglepulse-compression filtertobe matched foralldoppler-frequency shifts(alltargetvelocities) is2fr-28 [2rr.f02T(Bt)]s(r)=A(t)cos'--B- In1-l~T (11.55) Theamplitude A(t)ofEq.(11.55)represents modulation byarectangular pulseofwidthT. 
 DURATION WAVEFORMS PRESENT NO PROBLEM  THE RESULTS ARE EXTREMELY STABLE UNDER A WIDE VARIETY OF OPERATING CONDITIONS   AND THE SAME IMPLEMEN 
 It had a dial giving an indication of the amount of power being radiated and a light whichindicated when full power was being radiated. In early versions of the radar, the attenuator operated on both the transmitted and received signals. This was not usually a problem when homing onto a target atshort range but would have required careful coordination of the attenuator and receiver gain controls. 
 Long-wave airborne radar then inuse for sea search (Sec. 6.13) could beused fornavigation inthevicinity ofcoastlines, but interpretation ofitstype Ldisplay required long training even under the best circumstances, and was impossible over land, where themultiplicity ofecho signals was hopelessly confusing. Microwave airborne radar with PPI display was just coming into large-scale use, and itwas clear that thepicture ofthe ground afforded bysuch equipment would beauseful navigational aid over any sort ofterrain except the open sea. 
 UTED METEOROLOGICAL SCATTERERS  THEN THE RADAR CROSS SECTION OF THE WEATHER TARGET ALSO INCREASES WITH  S AS DETERMINED BY %QUATIONS  AND   AND THE SIGNAL 
 This is aimed  at giving a constant signal strength from a target of fixed RCS, independent of range.  These are often known as inverted  or inverse  cosec squared antennas to differentiate  them from air traffic control radar antennas that have their shaping at angles above the  horizon. Such shaping optimizes the pattern to the application, greatly enhancing over - all performance. 
 1972. 25Taylor. J.W.,Jr.:DigitalMTIRadarSystem. 
 In digital downconversion,  the analog IF signal is first sampled by an ADC, and all of the subsequent processing  is then done digitally. Figure 25.10 depicts the digital downconversion process for our  previous example, again in the frequency domain. The top line schematically repre - sents the real IF signal with parameters as before. 
 CLUTTER RATIO TO BE OPTIMIZED FOR THE PARTICULAR PRECIPITATION SCENARIO 4HE VERTICAL PATTERN OF A SHIPBORNE NAVIGATIONAL RADAR ANTENNA  NEEDS TO BE RELA 
 TER DOES NOT PRODUCE EQUAL IMPACT ON ALL PARTS OF THE RETURN PULSE AND GENERALLY HAS MINIMAL EFFECT ON THE CENTER OF THE PULSE  SO IT IS ESSENTIAL TO COLLECT DATA SAMPLES AT A MULTIPLICITY OF POINTS ACROSS THE RETURN  INCLUDING LEADING AND TRAILING EDGES 4HE TOTAL RADAR INSTABILITY IS THE RATIO OF THE SUM OF THE MULTIPLICITY OF RESIDUE POWERS AT THE OUTPUT OF THE DOPPLER FILTER TO THE SUM OF THE POWERS AT ITS INPUT  DIVIDED BY THE RATIO OF RECEIVER NOISE AT THESE LOCATIONS 3TABILITY IS THE INVERSE OF THIS RATIO BOTH ARE GENERALLY EXPRESSED IN DECIBELS. 
 System stability is characterized by the overall two-way (transmit and receive)  composite system frequency response, which is the return of a nonfluctuating target  as a function of doppler frequency. System frequency response should be defined by  the doppler passband.53 The focus of this section will be the stability requirements for  doppler frequencies separated enough from the carrier to be outside the ground mov - ing target notch. The concern in this region is white phase noise, which determines the  phase noise floor. 
 ONLY TABLES  AS SHOWN IN &IGURE   SO THAT THE EVOLUTION OF AIRCRAFT TACTICS  CAPABILITIES  AND HARDWARE DO NOT REQUIRE REWRITES OF VALIDATED SUBPROGRAMS 3OFTWARE VERSIONS BUILDS  ARE UPDATED EVERY YEAR THROUGHOUT THE LIFETIME OF THE SYSTEM  WHICH MAY BE DECADES %ACH SUBPROGRAM MUST HAVE TABLE DRIVEN ERROR CHECKING AS WELL -ANY LOWER LEVELS ARE NOT SHOWN IN &IGURES  AND  THERE MAY BE SEVERAL THOUSAND SUBPROGRAMS IN ALL 2ANGE $OPPLER 3ITUATION  -ODERN RADARS HAVE THE LUXURY OF INTERLEAVING MOST  OF THE MODES SUGGESTED IN &IGURE  IN REAL TIME AND SELECTING THE BEST AVAILABLE TIME OR AIRCRAFT POSITION TO INVOKE EACH MODE AS THE MISSION REQUIRES   4HE GEOMETRY THAT MUST BE SOLVED EACH TIME IS SHOWN IN &IGURE  4HE FIGHTER  AIRCRAFT PULSE DOPPLER GEOMETRY IS CENTERED AROUND THE AIRCRAFT TRAVELING AT A VELOCITY  6 A  AND AT AN ALTITUDE   H  ABOVE THE %ARTHS SURFACE 4HE RADAR PULSE REPETITION FREQUENCY &)'52%  -&!2 PRIORITY SCHEDULING . x°n  2!$!2 (!.$"//+  02&  GIVES RISE TO A SERIES OF RANGE         AND DOPPLER  X  Y  Z  AMBIGUITIES  AS  SHOWN IN &IGURE   WHICH INTERCEPT THE %ARTHS SURFACE AS RANGE hRINGSv AND ISO 
 B. Bluestein and R. M. 
 (These  limitations, however, do not apply when using the grid-controlled tubes known as  the Constant Efficiency Amplifier  or the Inductive-Output Tube , as discussed later in  Section 10.7.) Another approach to spectrum improvement is to shape the rise and fall of a rect - angular pulse.37 This attenuates the spectrum of frequencies far from fo, while the flat- topped portion of the pulse retains the high transmitter efficiency for most of the pulse  duration. Since a rectangular pulse has the best transmitter efficiency but has high  spectral energy at frequencies far from the center frequency, whereas a highly shaped  pulse has less far-out spectral energy but poor transmitter efficiency, the fraction of  the pulse length to be used for the shaped rise and fall is a crucial decision. Although the improvement attainable in practice is limited by phase modulation in  the transmitter during the rise and fall,38,39 significant improvements can be obtained. 
 141--157, March, 1959. Contains an extensive bibliography.  48. 
 Boerner, H. Mott, E. Luneburg, C. 
 8.7, uses a 3-dB hybrid junction with  balanced reflecting terminations connected to the coupled arms. Two switches (diodes) control  the phase change. The 3-dB hybrid has the property that a signal input at port 1 is divided  equally in power between ports 2 and 3. 
   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°Î ARRAY EQUAL LINE LENGTH   THE FEED NETWORK DOES NOT CONTRIBUTE TO A CHANGE IN PHASE WITH  FREQUENCY  AND SO ONLY THE APERTURE  EFFECT REMAINS 4HIS WILL B E DISCUSSED FIRST  AND THE  EFFECT OF THE FEED WILL FOLLOW !PERTURE %FFECTS  7HEN ENERGY IS INCIDENT ON AN ARRAY AT AN ANGLE OTHER THAN  BROADSIDE &IGURE    THE PHASE REQUIRED ON THE EDGE ELEMENT IS  X     O , K SIN P   .OTE THE  K IN THE DENOMINATOR 4HIS INDICATES THAT THE REQUIRED PHASE IS FREQUENCY 
 Radio Wave Propagation and the Ionosphere." Consultants Rureau. New York.  1973. 
 SHAPED OBJECT FORMED BY ROTATING AN ARC OF A CIRCLE ABOUT ITS CHORD  &)'52%   -EASURED AND PREDICTED BROADSIDE 2#3 OF A STRING STRETCHED  ACROSS THE TEST ZONE OF AN INDOOR TEST CHAMBER AT  n ANGLE Ú  (ORIZON  (OUSE 2EPRINTED WITH PERMISSION  &)'52%   -EASURED BROADSIDE RETURNS OF A THIN DIPOLE  #OURTESY OF  5NIVERSITY OF -ICHIGAN 2ADIATION ,ABORATORY  . £{°n  2!$!2 (!.$"//+  &IGURE  IS THE 2#3 PATTERN OF A K LONG  n HALF 
 The  heamwidth required of the primary feed pattern is determined by the illuminated portion of  the aperture. Li used a square-aperture horn with diagonal polarization in order to obtain the  required primary beamwidth and low primary-pattern sidelobes (better than 25 dB). The  Center of  sphere  Figure 7.15 Stepped parabolic reflector. 
 cc¯ ¯   8(E D .(DJ4   \  \VV V VV    4HE  IDEAL FILTER RESPONSE FROM THE STANDPOINT OF MAXIMIZING 3.2 IS THE MATCHED FILTER  THAT MAXIMIZES THE 3.2 AT TIME 4- WHEN   (8 E-J4-     VVV 
 D.' F., and W. D. Baker: Signal Processing Devices Using the Charge-Coupled Concept,  hlicroelectrorrics, vol. 
 Center frequency  9.6 GHz   Bandwidth  ≥150 MHz   Polarisation  horiz.; vert.   Transmit output power / TR -Module  ≥ 7W; ≥ 3W   Pulse length  25 - 50µs   Pulse repetition frequency (PRF)  1 - 3 KHz   Receiver gain  15 - 30 dB  . Radar System Engineering  Chapter 12 – Selected Radar Applications  160     Panel noise figure  £ 4.4 dB   Phase stability (temperature range -20° -  +60 °C) ± 10°   Panel radiated power (peak)  138 W   Panel power consumption   £ 123 W   Panel mass  14.2 kg     Before deployment the components and the overall system must undergo extensive test proc e- dures (e.g. 
 NOISE LEVEL OF  
 3 19-322. I EEE Cat. no. 
 51. Hall, W. M.: Antenna Beam-Shape Factor in Scanning Radars, IEEE Trans., vol. 
 TER RESIDUE  AND A  
 9. Cutler. C. 
 All these techniques make deception jamming or spoof- ing of the radar difficult, since the enemy should not know or anticipate the fine structure of the transmitted waveform; as a consequence, they give assurance of maximum range performance against jamming. Intrapulse coding to achieve pulse compression may be particularly effective in improving target detection capabil- ity by radiation of enough average radar power without exceeding peak power limitations within the radar and by improving range resolution (larger bandwidth), which in turn reduces chaff returns and resolves targets to a higher degree. Some advantage can be gained by including the capability to examine the jam- mer signals, find holes in their transmitted spectra, and select the radar frequency with the lowest level of jamming. 
 Ostro, “Planetary radar astronomy,” in The Encyclopedia of Physical Science and  Technology, 3rd Edition , R. A. Meyers (ed.), San Diego, Academic Press, 2002, pp. 
 The power density at the receiver then becomes:   € SR=PT⋅GT 4π2R()2 (3.10)  From this follow the received power PR  € PR=SRAR=PTGTGR⋅λ2 4⋅4π()2⋅R2 (3.11)  And the range of coverage is yielded by   € Rmax=PTGTGR⋅λ2 PRmin4⋅4π()2 (3.12)  For extended concave targets (e.g. Parabolic)  will be ~ p with p <  2 (focused) and for extended  targets with Rmax ~ p and p  > 2 (unfocussed).  The assumption is in all cases that the reflection  over the entire surface area of the extended object is well correlated, meaning, for example, that  no scattering appears. 
 J.: Design of Nonrecursive Digital Moving-Target-Indicator Radar Filters, Electro11ics 1-etter,  vol. 8, pp. 359-360, July 13, 1972. 
 AFT BEAMS 4HE 3EASAT AND  .3#!44 SPACEBORNE DOPPLER SCATTEROMETERS WERE DESIGNED WITH BEAMS POINTED  SQUINTED  AHEAD AND BEHIND THE NORMAL TO THE GROUND TRACK )NDEPENDENT 3AMPLES 2EQUIRED FOR -EASUREMENT !CCURACY  4HE 2AYLEIGH  DISTRIBUTION DESCRIBES THE FADING SIGNAL FAIRLY WELL )F WE ASSUME A 2AYLEIGH DISTRIBUTION  OF FADING  THE NUMBER OF INDEPENDENT SAMPLES REQUIRED FOR A GIVEN ACCURACY IS SHOWN IN &IGURE  4HE  RANGE DEFINED IN THIS FIGURE IS THE RANGE OF MEAN VALUES LYING BETWEEN   AND  OF POINTS ON THE DISTRIBUTION 4HIS ACCURACY RANGE IS INDEPENDENT OF ANY ACCU 
 A rectangular, or uniform, distribution describes the phase of a random  sine wave relative to a particular origin of time; that is, the phase of the sine wave may be  found, with equal probability, anywhere from O to 2n, with k = l/2n:. It also applies to the  distribution of the round-off (quantizing) error in numerical computations and in analog-to­ digital converters.  The constant k may be found by applying Eq. 
 The contact area between the whisker and the silicon isofthe order ofl~b cmz. Relatively low currents, therefore, yield high current densities, with attendant local heating and danger ofburnout. For continuously applied power thedanger line isoftheorder ofawatt; this would apply tothe flat part ofthe TR-tube leakage. 
 In order to mitigate speckle noise effects, we tested different speckle ﬁlter designs. Filters that were included in the testing were Frost [ 21], Enhanced Frost [ 22], Lee [ 23], Gamma-MAP [ 24], SRAD [ 25] and Non-Local Means [ 26]. In the end, Enhanced Frost ﬁlter was used in the algorithm due to its relatively straightforward implementation and comparable performance. 
 Eng., vol. 52, pp. 93-101, February 1982. 
 The TR is not a perfect switch; some transmitter power always leaks through to the  receiver. The envelope of the RF leakage might be similar to that shown in Fig. 9.8. 
 CONTOUR )N $ SPACE  THESE CONTOURS ARE CONCENTRIC SPHERES WITH THE RADAR AT THE CENTER &IGURE A  3IMILARLY  USING DOPPLER PROCESSING  THE RADAR CAN DISTINGUISH BETWEEN TARGETS OF  DIFFERENT APPARENT VELOCITIES )F  6 IS THE PLATFORM VELOCITY AND  P  IS THE ANGLE BETWEEN  6  AND THE ,/3 TO A STATIONARY TARGET  THEN THE APPARENT ,/3 SPEED OF THE TARGET IS  6 ,/3    
      . 
 Usingthemethodofinverseprobabil­ ity,Manasse8showed thattheminimum rmserrorinthemeasurement offrequency is (11.28)(11.27) where1 ¥=ex(2E/No)1/2 2f~<Xl(21tt)2s2(t)dtex=""'-------:------::---- J~<XlS2(t)dt ands(r)istheinputsignalasafunction oftime.Notethesimilarity between thedefinition ofex andfl.asdefined inEq.(11.16). aswellasbetween theexpressions for{)fand{)TR•The parameter exiscalledtheeffective timeduration orthesignal,and(ex/21t)2isthenormalized secondmoment ofS2(t)aboutthemeanepoch,takentobet=O.Ifthemeanisnotzero,but someothervalueto.theintegrand inthenumerator of(I1.28) wouldbe(21t)2(t-lo)2S2(t).[n radar,themeasurement errorspecified byEq.(1l.27)isthatofthedoppler frequency shift. Thevalueofex2foraperfectly rectangular pulseofwidthtis1t2t2/3;thustherms frequency erroris rectangular pulse -.j3 {)J-nt(2E7Noff/2 Thelongerthepulsewidth,thebettertheaccuracy ofthefrequency measurement.(11.29). 
 HUMPED  % FIELD IS REPRESENTED BY THE COMBINED  4%  AND 4% MODES SUBTRACTING AT THE CENTER AND ADDING AT THE 4% 
 LOOK  
 Younis, R. Lenz, and W. Wiesbeck, “Array Design for Automotive  Digital Beamforming Radar System”. 
 1,2,3&5)1.2 1 0.8Tracking Gains α, β 0.6 0.4 0.2 10−2 Accurate Radar Measurement Inaccurate Radar Measurement Low Maneuver Target Short Update Interval Long Update IntervalHigh Maneuver Target10−41001021041060 Tracking Index γ track FIGURE 7.28  The relationship between the steady-state tracking gains a  and b  is shown for different  Q(tk) s corresponding to different assumptions about the unknown target maneuver. Model no. 1: white  noise acceleration sampled at each measurement interval; model no. 
 16.6.—Doppler system for micro- scope. waves. Dotted lines show what must be added toordinary radar set. 
 ! MISSION PROFILE  . x°£{  2!$!2 (!.$"//+  RECONNAISSANCE #)32  ASSETS SEARCH AND ACQUIRE AIRBORNE TARGETS TRACK AND SEPARATE  BENIGN TARGETS FROM THREATS DELIVER WEAPONS ESCAPE AND ENGAGE IN COUNTERMEASURES MONITOR AND CALIBRATE ITS PERFORMANCE  AND RETURN TO BASE !IR 
 /1, 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar.  PULSE DOPPLER RADAR  4.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 where f0, f1, and f2 are the frequencies observed during the no-FM, FM-up, and   FM-down segments, respectively. 
 Thus, inspite ofcertain inadequacies, acathode-ray tube isused asthe radar indicator inallsituations that involve any appreciable target complexity. The picture presented onthetube face iscalled the indication, the display, orthe presentation. The tube itself isreferred toasthe indicator, indicator tube,display tube,CRT,orscope. 
 An example of the results of this work  is shown in Figure 21.15.FIGURE 21.14  Dielectric properties e′ (upper) and e″ (lower) of lossy soil as a  function of frequency ( Courtesy IEE )Frequency20 16 12 8 4 0 1.1081.10111.10101.109 ch21.indd   19 12/17/07   2:51:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 
 The circuits ofFigs. 16.6 and 169 areentirely equivalent asfarasthe output ofthe receiver isconcerned. The phase ofthe i-fecho signal from astationary target depends onthestarting phase ofthetransmitter, thestarting phase ofthelocal oscillator, and therange (which determines thenumber ofcycles executed bythelocal oscillator while thetransmitted pulse travels tothetarget and back). 
 Thefundamental limitation toaccuracy issystemnoisecausedeitherbymechani­ calorelectrical fluctuations. Sequential lobing,orlobeswitching, wasoneofthefirsttracking-radar techniques tobe employed. Earlyapplioations wereinairborne-interception radar,whereitprovided direc­ tionalinformation forhomingonatarget,andinground-based antiaircraft fire-control radars. 
 TO 
 Onsuch adisplay, the cartesian coordinates parallel and perpendicular totheaxis ofstretch retain their original meaning and their linearity, but they have different scale factors. Straight lines remain straight but, except for those parallel tothe coordinate axes, their directions are changed. Circles ofequal range appear asellipses with their major axes inthedirection ofthestretch. 
 Barton, Radars , vol. 3,   Ann Arbor: Books on Demand UMI, 1975. 49. 
 In one case the gain ratio k' is optimized at each value of pulse-to-pulse displacement. In the other compensated case the optimum gain ra- tio k is approximated by the linear function of interpulse platform motion kVx.(Q) UNCOMPENSATED (b) COMPENSATED . VxTp W FIG. 
 Aperture Radar Technol. Conf., pp. V-9-1-V-9-21, New Mexico State University, Las Cruces, Mar. 
 RANGE RESOLUTION  AND  RG IS THE  GRAY 
 The doppJer frequency shift is  . 211, 2v, Io Jd=-r =-c- (3.2a)  where f~ = transmitted frequency a11J c velocity of propagation = 3 x 108 m/s. If fd is in  hertz. 
 PERIODIC ANTENNAS USED IN THE */2. SYSTEM ARE UP TO  M TALL )N CONTRAST  THE CHOICE OF RECEIVING ANTENNA ELEMENT HAS TRADITIONALLY BEEN BASED ON THE )  -)#2/7!6% 2!$!2))  (& 3+97!6% 2!$!2 &REQUENCY CONSTRAINTS #AN BE SERIOUS  BECAUSE OF THE NEED FOR  WIDEBAND RADAR SYSTEMS AND BY COMPETITION FOR THE MICROWAVE FREQUENCY SPECTRUM BY COMMUNICATIONS AND OTHER ELECTROMAGNETIC SERVICESu  "OUNDED ABOVE BY THE STATISTICAL AVAILABILITY OF SKYWAVE PROPAGATION TO RANGES OF INTEREST u  "OUNDED BELOW BY SPECTRUM AVAILABILITY  ANTENNA SIZE  AND THE RAPID FALL 
 LOUS PROPAGATION  CAUSES RADAR RETURNS FROM CLUTTER  ON THE SURFACE OF THE %ARTH TO APPEAR #HAPTER . Ó°Ó  2!$!2 (!.$"//+  AT GREATLY EXTENDED RANGES  WHICH EXACERBATES THE PROBLEMS WITH BIRDS AND AUTOMOBILES   AND CAN ALSO CAUSE THE DETECTION OF FIXED CLUTTER HUNDREDS OF KILOMETERS AWAY 4HE CLUTTER MODELS CONTAINED IN THIS CHAPTER ARE APPROXIMATIONS OF THE TYPES OF  CLUTTER THAT MUST BE ADDRESSED 4HE EXACT QUANTITATIVE DATA  SUCH AS PRECISE SPECTRUM AND AMPLITUDE OF EACH TYPE OF CLUTTER  OR THE EXACT NUMBER OF BIRDS OR POINT REFLECTORS EG  WATER TOWERS OR OIL 
 89. P. H. 
 VORABLE CIRCUMSTANCES  EFFECTIVELY CUTS OFF PROPAGATION 4HUS  FOR EXAMPLE  IT WAS NOT POSSIBLE FOR THE  
 13.1  13.1 Introducti on  .............................................................  13.1  13.2 Description of the Sea Surface  ...............................  13.2  The Wave Spectrum  .......................................... 
 L. H.: Low-Noise Microwave Sources, International Co11ference on Radar-Present arul  Future, Oct. 23-25, 1973, IEE (London) Publ. 
 ª « ¬¹ º » 
 For example, the rate of land subsidence in Daqiao carbonate rock belt is lower than −5 mm/yr, indicating that the surface is relatively stable. Therefore, an area located on carbonate rock or soft soils is not sure to subside, but an area of subsidence requires natural conditions such as the carbonate rock or soft soils. In summary, natural factors are necessary but not sufﬁcient conditions for land subsidence. 
  
 15.34  15.9 Staggered PRF  .......................................................  15.34  Stagger Design Procedures  ...............................  15.34  Feedback and Pulse-to-Pulse  Staggering  .......... 
 CAL CHARACTERISTICS  -AGELLANS ELLIPTICAL ORBIT WAS INCLINED AT  n  WHICH ALLOWED  VIRTUALLY FULL ACCESS TO THE SURFACE BY THE SIDE 
 The achievable degree of superresolution depends heavily on the way in which the algorithms are implemented. The required accuracy of signal quantization and the matching of channels are comparable with those of adaptive nulling. The heavy computational task required by the algorithms can be handled by resorting to systolic array processors.60 Experiments indicate that the resolution limit is determined rather more by implementation factors like channel mismatching errors than by the pure SNR. 
 HF SKYWA VE  RADAR Type chosen for comparison Long-range air traffic  control such as ARSR-3Joint aircraft and ship detection, two- site radar such as Jindalee, JORN, and  ROTHR Major antenna dimension (m) 10–15 1000–3000 Average transmit power (kW) 4 400  Antenna radiation pattern Fully defined by antenna  constructionStrongly influenced by ground  properties around antenna Typical operating range (km) 280–450 1000–4000 Minimum range (km) 1000 Range resolution (m) 300 1500–15000 Propagation medium •  Homogeneous or  stratified • Nondispersive • Isotropic • Stable • Linear • Nearly constant•  Structured horizontally and  vertically, both deterministically and  randomly, on many scales • Frequency dispersive • Anisotropic (magnetoionic) • Highly dynamic • Weakly nonlinear •  Varies dramatically with time of  day, season, etc. Radar signal propagation path • Line-of-sight •  Usually unique; may  have simple ground- reflection multipath • Relatively stable• Reflected from ionosphere •  Multiple paths, resulting in multiple  echoes from a single target, at  different apparent ranges, bearings,  elevation angles, and doppler shifts • Unstable •  Poorly known, must be inferred  from ancillary sounding systems Dominant propagation effects  on the radar signal•  Multipath interference  between direct and  surface-reflected signals• Attenuation • Focusing and defocusing • Polarization transformation • Phase modulation • Wavefront distortion Target scattering regime Optical (high frequency),  i.e., target size  radar  wavelengthRayleigh – resonance, i.e., target size   < or ∼  radar wavelength Clutter •  Can be serious,  especially at short  ranges •  Minimized by narrow  beam, short pulse, and  doppler processingLook-down viewing geometry  inevitably results in strong ground  echoes at the same range as the target,  typically 20–80 dB stronger than the  target echo Doppler processing Widely used for detection  of moving targets in clutterEssential to separate moving targets  from strong clutter returnsTABLE 20.1  Key Differences Between Microwave Radar and HF Skywave Radar   (The parameter values quoted here are intended to be broadly representative, rather   than an attempt to span all known systems.) ch20.indd   9 12/20/07   1:15:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
  
        ())% * %( #,.-&+ &)'52%   -EASURED SPECTRA OF CLUTTER FROM FOREST 3EVERAL WIND  SPEEDS AND AN ESTIMATED VALUE OF  A  HAVE BEEN ADDED  AFTER *" "ILLINGSLEY  Ú 7ILLIAM !NDREW 0UBLISHING )NC   4!",%  -EASURED 3PECTRAL 3PREAD FOR $IFFERENT 7IND #ONDITIONS AFTER *""ILLINGSLEY   Ú 7ILLIAM !NDREW 0UBLISHING )NC      7IND   #ONDITIONS7IND 3PEED  MPH %XPONENTIAL AC 3HAPE   0ARAMETER A  MS  2-3 3PECTRAL   7IDTH R V MS  4YPICAL 7ORST #ASE 4YPICAL 7ORST #ASE ,IGHT AIR n     "REEZY  n     7INDY n        'ALE FORCE EST  n        .   -4) 2!$!2  Ó°£x ! COMPARISON BETWEEN THE GAUSSIAN AND THE EXPONENTIAL MODELS ON A LINEAR SCALE   AS SHOWN IN &IGURE   INDICATES THAT THE DIFFERENCE IN SPECTRAL WIDTH AT EVEN VERY  LOW LEVELS n D"  IS NO MORE THAN ABOUT A FACTOR OF  &OR MANY ANALYSES  THIS WOULD MOST LIKELY BE INSIGNIFICANT COMPARED TO THE ADDED CLUTTER SPECTRAL SPREADING CAUSED BY SCANNING MODULATION 4HUS  IN MANY CASES  THE SIMPLE GAUSSIAN MODEL CAN CONTINUE TO BE USED IN -4) AND -4$ PERFORMANCE ANALYSIS )N CASE OF DOUBT  THE SPECTRAL SPREAD OF THE GAUSSIAN MODEL COULD BE DOUBLED TO ASSESS THE AVAILABLE MARGIN .ATHANSON AND 2EILLY  HAVE SHOWN THAT THE CLUTTER SPECTRAL WIDTH OF RAIN IS PRI 
 76-80, July,  1963.  68. Loughren. 
 Based on Ref. [ 29], the Batch Orthogonal Matching Pursuit (Batch-OMP) algorithm can be used in this step. In the second stage, the dictionary atoms are updated 265. 
 As the wind speed increases, higher-order components appear at $fd. Jfd. etc. 
 Another way of  analyzing this phenomenon is in terms of aperture fill time. As shown in Figure 13.24,  the time it takes to fill the aperture with energy is  τ=L csinq0  If the bandwidth is chosen to be equal to the aperture fill time t = L /c sin q0, this  is equivalent to bandwidth (%) = 2 beamwidth ( °). Hence, a loss of 0.8 dB can be  expected if the pulse width is equal to the aperture fill time. 
 The radar cross section of a sphere is independent of the aspect at which it  is viewed: consequently, its echo will not fluctuate with time. The same is true, in general, of a  radar beacon if its antenna pattern is omnidirectional. However, most radar targets are of a  more complex nature than the sphere. 
 Forward-aspect Search uses high-duty high-PRF wave - forms to maximize the energy on target and provide long detection range. Forward- aspect Search waveforms include Velocity Search  (VS), High-PRF Range-While-Search   (HRWS), and Alert /Confirm . All-aspect Search can be either a single high-medium PRF  waveform that has acceptable performance for targets that are competing with sidelobe  clutter, or the combination of Forward-aspect Search high-PRF waveforms interleaved  with medium-PRF waveforms designed to detect targets competing with sidelobe clut - ter, such as Medium-PRF Range While Search  (MRWS). 
 For a transmitter near the surface, the  reflection process results in two paths to a receiver within the line of sight. As stated above, upon reflection, a portion of the energy is propagated in the direc - tion of initial wave motion. A portion of energy is also reflected backward toward the  transmitter. 
 The raised threshold causes a loss in target sensitivity and is referred to as a CFAR  loss. This loss has been calculated22 and is summarized in Table 7.1. As can be seen,  for a small number of reference cells, the loss is large because of the poor estimate of  s. 
 Iftheappearance oftheazimuth pulse atshort range ontheindicators isnot tolerable, atriggered modulator can befired after the azimuth pulse, thedelay from thethird coded pulse being precisely fixed. Atthe receiver asimilar delay initiated bythe decoded basic pulse can be inserted ‘ahead ofthe indicators. Correct adjustment ofthis delay can easily bemade byobserving the transmitter pulse appearing with the video signals. 
 and F. C. MacDonald: Terrain Clutter Measurements in the Far North, Report of  NRI, I'royri~ss. 
 Barton, “Land clutter models for radar design and analysis,” Proc. IEEE , vol. 73,   pp. 
 In the moving target channel, the threshold obtained from  the clutter map content is scaled down by the expected clutter attenuation. In addition  to the clutter map thresholding, conventional constant false alarm rate thresholding  is utilized against moving clutter (rain) and interference. Detection outputs, named  Primitive Target Outputs , are obtained through this processing for each individual pro - cessed CPI. 
 THE 
 #7 SCATTEROMETER ARE SHOWN IN &IGURE  4HE  SWEPT OSCILLATOR MUST PRODUCE A LINEAR SWEEP THIS IS EASY WITH YTTRIUM 
 When these precautions areobserved, free-running stabilities ofaround 1kc/sec2 can beobtained at30Me/see. Atypical oscillator with itspreceding and following stages isshown inFig. 16.27. 
 363-400, July 1984. 10. Cutrona, L. 
 xiv John P. Stralka Northrop Grumman Corporation (CHAPTER 4) Roger Sullivan Institute for Defense Analyses (CHAPTER 17) Byron W. Tietjen Lockheed Martin Corporation (CHAPTER 8) G. 
 TO 
 ARRAY ARCHITECTURE  AND NO TAPERING         
 CESSING TECHNIQUES "ECAUSE ALL SHIPS ABOVE  GT NEED TO CARRY AT LEAST A SINGLE  '(Z RADAR  IT MEANS THAT RACON AND 3!24  DETECTION CAPABILITY IS MAINTAINED 4HIS APPROACH GIVES )-/ AN INDEFINITE PERIOD TO ASSESS THE IMPACT OF THE NEW REGU 
 In tube displays so far we have considered only that  type wherein a coated surface is caused to fluoresce on  impact of the electron stream, and the radar operator  sees this pattern on the tube end itself. But we must  also note the extremely important new technique opened  by r tubes | of the Skiatron type, where the picture is not °  watched | on the tube.end, but is projected optically on to  a large screen. The fluorescent screen used on Skiatron-  type tubes does not show much apparent change to the  human eye when the electron beam traces out its pattern,  but. 
 FOURTH BEAMWIDTH ON ONE SIDE OF THE DESIRED DIRECTION TO ONE 
 Thesearecalledpolyphase codes.16.24Thetime sidelobesofapolyphase codecanbelowerthanthoseofthebinaryphase-coded waveform of similarlength.63.64However, theperformance ofpolyphase codesdeteriorates rapidlyinthe presence ofadoppler-frequency shiftandtherefore theyhavebeenlimitedtosituations where thedoppler isnegligible. Otherbinarycodingmethods thathavebeenconsidered forpulsecompression include:35 (1)compound Barkercodesforobtaining longercodesfromtheBarkerseriesbycodingseg­ mentsofoneBarkercodewithanother Barkercode(alength13Barkercodecompounded withinanotherlength13codegivesapulse-compression ratioof169andape¥sidelobe of -22.3dB);(2)codesequencing 011successive PRFperiods,inwhichaditTerent codeisusedfor eachtransmission toproduce randomsidelobeswhichwhenNpulsesareaddedtoproduce a J"Nimprovement inmainlobe-to-sidelobe amplitude ratio,whereNisthenumber ofse­ quencesemployed; and(3)complementary codesinwhichapairofequal-length codeshavethe property thatthetimesidelobesofonecodearethenegative oftheothersothatiftwocodesof acomplementary pairarealternated onsuccessive transmissions, thealgebraic sumofthetwo autocorrelation functions iszeroexceptforthecental peak~36.37 Apulseburstisawaveform inwhichaseriesofpulsesaretransmitted asagroupbefore anyoftheechosignalsarereceived.Itisusedtoobtainsimultaneous rangeanddoppler­ velocityresolution whentheminimum rangeisrelatively lon~;asforradarswhosetargetsare extraterrestrial, suchassatellites andballistic missiles. Pulsecompression mightbeappliedto eachoftheindividual pulsesoftheburstforbetterrangeresolution, andamplitude weighting ofthepulseburstmightbeusedtolowerthedopplersidelobe leveltoimprove thedetection of smalldoppler-shifted targetechoescloseinfrequency tolargeclutterechoes. 
 required for II mode operation. The elimination of the straps allows the resonators to be  designed for optimum efficiency rather than as a compromise between efficiency and mode  control.  The power handling capability of a magnetron depends on its size. 
 The radar should he designed conserva­ tively with larger power and larger antenna aperture than the minimum required for marginal  detection.  One of the better measures against many forms of ECM is an alert, highly motivati.:d, well  trained, and experienced operator.  Noise jamming. 
 WAVE OSCILLATIONS )N &IGURE   ATTENUATION IS SHOWN ALONG THE HELIX SO AS TO PREVENT OSCILLATION DUE TO REFLECTIONS AT THE OUTPUT AND THE INPUT OF THE STRUCTURE 4HE ATTENUATION MAY BE DISTRIBUTED OR LUMPED  BUT IT IS USUALLY FOUND IN THE MIDDLE THIRD OF THE TUBE !LTHOUGH OSCILLATION CAN BE PREVENTED BY DISTRIBUTING LOSS ALONG THE STRUCTURE  IT RESULTS IN LOWER EFFI 
 8.14. Since the attenuation  in the transmission line connecting adjacent elements is small compared with that of conven­ tional phase shifters, the series-fed arrangement can be used in frequency-scan arrays without  excessive loss.  -d- Input 0 Direction of  main beam  dieting elements  Termination  Snoke feed/ Figure 8.14 Series-fed, frequency-scan linear array. 
 35. Mavroides. W. 
 This rules out methods ofmounting the units inwhich the support brackets attach Although rectangular containers aremost economical ofspace, they aredifficult topressurize because oftheir tendency tobecome spherical under pressure, with resultant severe shear strains inthe corners. Ina ship set,where only small pressure differentials areexpected, arectangular cover isfeasible. Ifitisnottoolarge, arectangular housing cast outof light metal canbemade strong enough tostand the30lb/inz test pressure required forairborne r-fheads. 
 %   
 224 INTRODUCTION TO RADAR SYSTEMS  Directive gain. A measure of the ability of an antenna to concentrate energy in a particular  direction is called the gain. Two different, but related definitions of antenna gain are the  directive gain and the power gain. 
 11.11 or 11.13b) is an example. The presence of additional  spikes can lead to ambiguity in the measurement of target parameters. An ambiguous measure­ ment is one in which there is more than one choice available for the correct value of a  parameter, but only one choice is appropriate. 
 FOURTH OF A LOCAL BEAMWIDTH FREQUENCY  IE    #RITERIONSCANNED $P P "a  7 ITH A SCAN OF n  THIS GIVES +     AND IN TERMS OF BROADSIDE BEAMWIDTH THE LIMIT IS   "ANDWIDTH     BEAMWIDTH n   #7   &OR EXAMPLE  IF THE ARRAY HAS A BEAMWIDTH OF  n THIS CRITERION PERMITS A  CHANGE  IN FREQUENCY PRIOR TO RESETTING THE PHASE SHIFTERS 4HIS ALLOWS THE BEAM TO MOVE FROM  ONE 
 The required tracked target accuracy at 95% levels is given in  Table 22.4. FIGURE   22.5 Kelvin Hughes SharpEyeTM CMR S-band solid-state transmitter ( Courtesy of Kelvin  Hughes Ltd. ) ch22.indd   17 12/17/07   3:02:35 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 IfweletP~irepresent the peak value ofavailable recei~-ed power necessary fortriggering the l~eacon and l?!represent the corresponding. SEC. 85] INDEPENDENCE OFINTERROOA TIONANDREPLY 255 range, Eq. 
 Parker, “Vacuum electronics for the 21st  century,” IEEE Microwave Magazine , pp. 61–72, September 2001.  9. 
 TROUGH HEIGHT OF THE ONE 
 A. H., 113  Bowen, E. G., 25, 26  Breit, Dr Gregory, 20  Butement, Dr W. 
 3EARCH  ,IKE 63  (273 IS A HIGH 
 The availability of  digital data processing technology has made ADT economically feasible. An ADT system  performs the functions of target detection, track initiation, track association, track update,  track smoothing (filtering) and track termination.  The automatic detector part or the ADT quantizes the range into intervals equal to the  range resolution. 
 Apulse length of1psec was finally chosen forthefollowing reasons: 1.Average power output was pushed tothe safe upper limit forthe transmitter with avalue of750 kwforpulse power, apulse recur- rence frequency of400, and al-~sec pulse length. 2.Reduction ofthe pulse recurrence frequency to200 with acorre- sponding increase ofpulse length to2psec would have given an appreciable increase inR~,.ifthis change ledtonoreduction in pulse power orinaverage power. Since the magnetron then available performed better both inpulse power and inaverage power at1psec than at2psec, therealization ofany improvement inR-,would have been doubtful. 
 No  longer do we have a stationary trace, with an echo  deflected. The usual arrangement is for intensity modu-  lation to be applied by varying signal voltages on the  grid of the CRT. That produces for us our brighter  spot on the reception of a signal. 
 TO 
 OF 
 Trunk. J. [I. 
 6, pp. 356-365, Nov., 1967. Also, Report of N RL Progress, pp. 
 Appl. MeteoroL, vol. 25, pp. 
 The SAR aboard the Japanese Earth Resources Satellite14 (J-ERS-1)  was similar to Seasat, being at L band, with an H-polarized 11.9 m by 2.4 m antenna.  Its 38 ° incident angle,* which is larger than that of Seasat, was enabled by its lower  altitude and larger antenna aperture. Its 1.1 kW peak power was comparable to that of  Seasat. 
 In Proceedings of the 2006 IEEE International Symposium on Geoscience and Remote Sensing (IGARSS), Denver, CO, USA, 31 July–4 August 2006. [ CrossRef ] 29. Martorella, M.; Berizzi, F.; Giusti, E.; Bacci, A. 
 The antenna  may be regarded as an array of subarrays. The subarray pattern forms the element fac - tor; it is steered by phase shifters in the desired direction, but it scans with frequency  as indicated by Eq. 13.26. 
 8  4ERRA3!2 
 Adaptive weights are generated and applied to the 18 receive channels, form - ing three beams (Sum, Deltaaz, and Omni) by weighting and summing the 18 receive  channels over three pulses to provide simultaneous clutter and jamming cancellation.  The adaptive weight algorithm is matched to the radar’s operating parameters and is  augmented with adaptive knowledge–aided sampling schemes to maximize perfor - mance in a complex, heterogeneous clutter and jamming interference environment.  Doppler filtering is performed after digital beamforming. 
 PS-22, pp. 713–718, October 1994. 22. 
 TONE SECOND AND THIRD ORDER INPUT INTERCEPT POINTS 4HE INTERCEPT POINT IS THE EXTRAPOLATED LEVEL AT WHICH THE POWER IN THE INTERMODULATION PRODUCT EQUALS THAT OF THE TWO FUNDAMENTAL SIGNALS &OR INPUT SIGNALS AT FREQUENCIES  F  AND F  SECOND ORDER INTERMODULATION DISTORTION  PRODUCES SIGNALS AT FREQUENCIES    F  n F   F    F  F AND F 4HIRD ORDER INTERMODU 
 Finite length words for filter coefficients produce non- ideal filter responses. The effect on passband response is typically negligible, but  significant distortion of the filter stopband rejection can occur, potentially effecting  I/Q balance. Digital Downconversion Using Multirate Processing and Polyphase  filters. 
 4RANSMITTERS  -OST OF THE RADAR DESIGNS AND MISSIONS REQUIRE TRANSMITTER AVER 
 STRING HARDWARE IN MOST IF NOT ALL SUBSYSTEMS OTHER THAN THE ANTENNA /RGANIZATION OF THE #HAPTER   4HE CHAPTER SECTIONS ARE ORGANIZED BY MEASURE 
 75 CIIO 938-1 AES.  80. Meyer, J. 
 Anabsorber ofthesecond kind was also developed inGermany. It consisted ofaseries oflayers whose conductivity regularly increased with depth. The layers were separated byafoam-type plastic whose dielectric constant was close to1.The absorption was excellent from 4to13cm. 
 TO 
 A linear aperture of length D, with aspect angle orthogonal to the transmitter LOS, will roll off 3 dB at (TT - p) = X/2Z), where Dl\ > 1. The forward-scatter RCS rolloff continues, with sidelobes approximating sinx/x over the forward-scatter quadrant (P > 90°).105 For other aspect angles and targets with complex shadow apertures, calculation of the forward-scatter RCS rolloff usually requires computer simulation. The forward-scatter RCS of more complex bodies has been simulated and measured; the bodies were both reflecting and absorbing.34'37'38'92'98'100"102 Paddison ct al.100 report both measurements and calculations via computer sim- ulation of forward-scatter RCS for a right circular aluminum cylinder at 35 GHz and bistatic angles up to 175.4°. 
 Ruetz: High-Power Linear-Beam Tubes, Proc. IEEE, vol. 61,  pp. 
 42. Schaper, L. W., Jr., D. 
 Eithersystemcanbeusedseparately (simplex operation) orbothcanbeused simultaneously (diplexoperation). Thechiefreasonforthedualchannels inthisradaristo providegreateravailability oftheradar.Afailureinonechanneldoesnotrequiretheradarto shutdown.Theradaroperates withasinglechannel whilerepairsarebeingmade.The availability ofdual-channel radarswithbuilt-in-test equipment andfaultisolation hasbeen demonstrated tobeconsiderably greaterthan99percent. Highavailability alsorequires that sparepartsbeathandwhenneededandthatmaintenance personnel beexperienced and motivated. 
 PASS IMPEDANCE 
 (7.3) it can be shown that  Note that the relative reduction in gain is independent of the number ofelements and depends  only on the fraction of elements that are operative and the mean square value of the errors.  When P, = 1 and A = 0, the expression is, for small-phase errors, similar to that of Eq. (7.30)  for the confinuous aperture. 
   -%4%/2/,/')#!, 2!$!2   £°£x AT THESE WAVELENGTHS  3PACE 
   )%%%  /CTOBER   2 - 7AKIMOTO AND 2 # 3RIVASTAVA EDS    2ADAR AND !TMOSPHERIC 3CIENCE ! #OLLECTION OF  %SSAY IN (ONOR OF $AVID !TLAS  -ETEOROLOGICAL -ONOGRAPHS  6OL   "OSTON !-3    0 -EISCHNER ED    7EATHER 2ADAR 0RINCIPLES AND !DVANCED !PPLICATIONS   "ERLIN 3PRINGER 
 Aerosp. Electron. Syst. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.40  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 With pulse-to-pulse staggering, good response can be obtained on all dopplers of  interest on each scan. 
 L. Britton, T. W. 
 which yields a single-sided spectrum that is significantly narrower than the spec- trum abeam. For moderate platform speeds and lower-frequency (UHF) radars this effect is negligible, and compensation is not required. When it is necessary to compensate for this effect, the phase center of the an- tenna must be displaced ahead of the aperture and behind the aperture for alter- nate receive pulses so that the phase centers are coincident for a moving plat- to) FIG. 
 Joint Advanced Strike Technology Program, “Avionics architecture definition 1.0,” U.S. DoD  public release, unlimited distribution and use, pp. 9, 11, 31,32, 1994. 
 Jr .. and T. H. 
 MULTIPLEXED BEAMS WHEN HITCHHIKING OFF  THE !7!#3 TRANSMITTER FOR SHORT 
 Similarly, more than  one positively charged anode may be used, so that the  electron (negatively charged) beam has to pass through  several cylinders or apertures in discs on its outward  route. These voltages, applied to each stage of electrode,  can be so adjusted that there is a varying electric field,  and at each point the beam can be deflected just as rays  of light would be deflected by an optical lens. The  shield near the cathode is usually known as the grid,  and because of its geometric position has the same con-  trolling effect on the electron beam as has the mesh grid  of an ordinary radio valve. 
 We  convert this to crossrange by multiplying by l/2Ω = lR/2V:  δλ λ λ λ cr SA≈ = ≈ =2 2 2 2 Ω ∆TR LR VT q (17.8) Note that our assumption that R  VT permits the use of small-angle approxima - tions for small ∆q. When ∆q is not small, Eq. 17.8 must be appropriately modified. 
 These modes provide the difference signals, and no comparators, as shown in Fig. 18.8, are used.12 Generally, mode-coupling devices can give good performance in separating the symmetrical and unsymmetrical modes without significant cross-coupling prob- lems. Multiband monopulse feed configurations are practical and in use in several systems. 
 The band occupied by the signal is B, and the carrier frequency is fo. This expression for the  doppler-talerant waveforrri is difficult to interpret as it stands, but if the natural-log factor is  expanded in a series, Eq. (1 1.55) becomes  I~B~Z 27~~~t3 s(t) = A(!) cos 2rtfot -t + -- + ... 
 24  The Neyman-Pearson Observer is equivalent to examining the likelihood ratio and deter­ mining if Lr(v) ?: K, where K is a real, nonnegative number dependent upon the probability of  false alarm selected.  Inverse probability receiver. A detection criterion that has been popular particularly for the  theoretical analysis of statistical detection and for statistical parameter estimation is that  based on inverse probability. 
 ING WAVE SCATTER  CONSTRUCTING A METALLIC MODEL OF A BREAKING WAVE  COMPARING ITS . 
 When the primary feed pattern is 10 dB down at the edges, the first minor  lobe in the secondary pattern is in the vicinity of 22 to 25 dB.  Calculations of the antenna efficiency based on the aperture distribution set up by the  primary pattern as well as the spillover indicate theoretical efficiencies of about 80 percent for  paraboloidal antennas when compared with an ideal, uniformly illuminated aperture. In prac­ tice, phase variations across the aperture, poor polarization characteristics, and antenna mis­ match reduce the efficiency to the order of 55 to 65 percent for ordinary paraboloidal-reflector  antennas. 
 The amount of noise which enters the antenna depends upon the entire antenna radiation  pattern, including the sidelobes and the type of objects they illuminate. Land is almost a  complete absorber; hence those portions of the radiation pattern which illuminate the ground  see a noise source at the ambient temperature. Perfectly reflecting sources, such as a smooth sea J/  or a road, act as a mirror to reflect the'radiation from the sky or other objects. 
 Figures 7.24 a and 7.24 b also illustrate some of the challenges of automatic track - ing. Detections are made on targets, but some detections are missing because of target  fades or multiple targets in the same resolution cell, whereas additional detections are  present due to clutter or noise. FIGURE 7.24 a Thirty-minute time lapse of AN/FPN-504 (L band) air traffic  control radar detections over a ±400-km square area (after H. 
 35. Gustafson, B. G., and B. 
 Radio me trie Homing. This mode utilizes the natural thermal radiation from targets for guidance. The very sensitive receiver detects the difference in radia- tion between the target and the ambient background. 
 The first sidelobe of the filters described by Eq. (4.16)  has a value of -13.2 dB with respect to the peak response of the filter. If this is too high for  proper clutter rejection, it may be reduced at the expense of wider bandwidth by applying  amplitude weights wi. 
 The receiver  noise-figure with a mixer front-end is then  F2 -l F0 = F1 + G, = Lc{t, + FIF -1) (9.13)  (This does not include losses in the RF transmission line connecting the rc.ceiver to the  antenna.) If, for example, the conversion loss of the mixer were 6.0 dB, the IF noise figure 1.5 dB,  and the noise-temperature ratio 1.4, the receiver noise figure would be 8.6 dB. For low-noise­ temperature-ratio diodes, the receiver noise figure is approximately equal to the conversion  loss times the IF noise figure.  Balanced mixers. 
 Eom and A. K. Fung, “A scatter model for vegetation up to Ku-band,” Remote Sensing  Environ ., vol. 
 J. Ronen and R. H. 
 The practice of using the earth's surface for height finding was quite common in early radar because antenna and transmitter technologies were limited to lower radio frequencies and broad elevation beams. The first United States operational shipborne radar, later designated CXAM and developed in 1939 by the U.S. Naval Research Laboratory (NRL), used the range of first detection of a target to estimate its height, based on a knowledge of the shape of the pattern near the horizon due to the primary multipath null. 
 Graph. Stat. 2001 ,10, 1–50. 
 pp. 630 636,  September, 1973.  69. 
 CESSING AND DIGITIZATION OF THE INDIVIDUAL PULSE SIGNALS WITH THE MINIMUM OF DISTORTION  ENABLING SUBSEQUENT DIGITAL SIGNAL PROCESSING TO MAXIMIZE THE PERFORMANCE OF THE RADAR 4HE DIGITAL SIGNAL PROCESSING FUNCTION IS NOT NORMALLY CONSIDERED TO BE PART OF THE RECEIVER È°ÓÊ  "- 
 The order of magnitude increase in range possible with an  IIF 0TH radar as compared with conventional microwave radar makes it attractive for  coverage of those geographical areas where it is not convenient to locate line-of-sight radars.  The observation of targets over large areas of the sea is an example where HF 0TH radar can  find effective applications. The unique properties of these radars also make them of interest for  military applications. 
 FROM 
 RANGE GROUND OR AIR TARGET LOCATION ONLY DOPPLER AND COARSE  $/!  DATA ARE AVAILABLE  WHICH SEVERELY RESTRICTS LOCATION CAPABILITY  AS OUTLINED IN 3ECTION  4HUS  THE LOW %20 OF THESE TRANSMITTERS CONSTRAINED BY THE AVAILABLE BANDWIDTH CONSPIRE TO SIGNIFICANTLY REDUCE THEIR UTILITY FOR 0"2 SURVEILLANCE 4HE TYPE OF MODULATION USED BY A BROADCAST TRANSMITTER IS PARTICULARLY IMPORTANT &OR  EXAMPLE  THE  #RYSTAL 0ALACE 46 TRANSMITTER TRIALS IN ,ONDON  ATTEMPTED RANGE  MEASUREMENTS WITH ANALOG 46 WAVEFORMS BUT FOUND THAT THEY GENER ATED HIGH RANGE SIDE 
 Edelberg, S., and A. A. Oliner: Mutual Coupling in Large Arrays: pt. 
 BAND SINGLE FREQUENCY 0RECIPITATION  2ADAR 02  AND A  M SINGLE BEAM ARRAY ANTENNA THAT IS STEERED  n ON EITHER SIDE  OF THE SPACECRAFT TRACK )TS RELATIVELY LOW INCLINATION ORBIT AT  KM ALTITUDE PROVIDES TROPICAL PRECIPITATION MEASUREMENTS WITH  M RANGE RESOLUTION AND A  KM FOOT 
 The impedances of the side arms Aand Balways had equal and opposite reactive components since they differed in length by a 1/4 wavelength and the two branch arms of the attenuator always had a total impedance equal to the impedance of the Figure 4.3. TR switch and anti-TR switch arrangement.Airborne Maritime Surveillance Radar, Volume 1 4-5. transmitter waveguide. 
 THE 
 In principle, the computer can be programmed to recognize and reject these un­ wanted signals, hut this is an inerficicnl method for eliminating them. It is more convenient to  eliminate them in the radar signal-processor hy either analog l111lk-rrocessi11y or its special­ purpose diµital equivalent. Such signal processing includes matched filtering. 
 (EIDEN  h!NTI 
  
 STATE SYSTEM  HAVE NOT SEEN THE SUCCESS ONCE ENVISIONED DUE TO THE ACQUISITION COST OF SOLID 
 Methods for the design of optimal receivers for the detection of moderately  fluctuating signals have been considered.46  It is difficult to be precise about the statistical model to be applied to any particular  target. Few, if any, real targets fit a mathematical model with any precision and in some cases  it is not possible to approximate actual data with any mathematical model. Even if the  statistical distribution of a target were known, it might be difficult to relate this to an actual  radar measurement since a target generally travels on some well-defined trajectory rather than  present a statistically independent cross section. 
  
 ING  CUEING  TRACKING  AND MULTISENSOR FUSION OF DETECTIONS 4HE AIM OF THIS APPROACH IS TO PROVIDE A SHARED POOL OF COMPUTATIONAL RESOURCES  WHICH MAY BE FLEXIBLY ALLOCATED BETWEEN SENSORS AND FUNCTIONS 4HE SENSORS MAY CONTAIN DEDICATED  MOTION SENSING  BUT LONG 
 NOISE RATIO COMES WITHIN THE SURFACE 
 In the other, the proper length of line is made up of the series  conibiriation of a relatively few selected lengths of line. This is a series-line, or a casc.citlrt1.  configuration. 
 On Microwave Theory and Techniques, vol. 43, no.  7. 
 Rignot, E.; Zimmermann, J.R.; Vanzyl, J.J. Spaceborne applications of P-band imaging radars for measuring forest biomass. IEEE T rans. 
 c¯ ¯'      REGULARIZED LOWER INCOMPLETE GAMMA FUNCTION 4HE INTEGRAL OF THE CHI 
 Bates: Doppler Radar Boast Design Innovations, Microwat•es, vol. 13,  pp. 72-82. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters.  SOLID-STATE TRANSMITTERS  11.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 banks of final output modules, 17.5 kW, was provided from the combined outputs of  12 more identical modules in the driver group. 
 SAMPLING AND DIGITAL BASEBANDING 4HE DIGITAL )& 
           .   4(% 02/0!'!4)/. &!#4/2  &0  ). 4(% 2!$!2 %15!4)/.   ÓÈ°£Î 4HE RESULTANT INVERSION IS REFERRED TO AS THE TRADEWIND INVERSION AND MAY CREATE A  STRONG DUCTING CONDITION AT THE TOP OF THE MARINE BOUNDARY LAYER %LEVATED DUCTS MAY  VARY FROM A FEW HUNDRED METERS ABOVE THE SURFACE AT THE EASTERN PART OF THE TROPICAL OCEANS TO SEVERAL THOUSAND METERS AT THE WESTERN PART &OR EXAMPLE  ALONG THE SOUTHERN #ALIFORNIA COAST  ELEVATED DUCTS OCCUR AN  AVERAGE OF  OF THE  TIME  WITH AN AVERAGE  TOP ELEVATION OF  METERS !LONG THE COAST OF *APAN  ELEVATED DUCTS OCCUR AN AVERAGE OF  OF THE TIME  WITH AN AVERAGE TOP ELEVATION OF  METERS )T SHOULD BE NOTED THAT THE METEOROLOGICAL CONDITIONS NECESSARY FOR A SURFACE 
 tile electric field is perpendicular to the plates (H field parallel}; thus the velocity of the  wave which propagates through the plates is relatively unaffected provided the plate spacing is  Figure 7.20 X -hand mclal-plale zoned Jens. 252 INTIWDUCTION TO RADAR SYSTEMS  great a than )./2. The direction of the rays is not affected by the refractive index, and Snell's law  does not apply. 
 Paving  also reduces maintenance of the ground plane, such as might be required by periodi - cally removing vegetation and smoothing out windblown ridges in unstable soil. The angle of incidence and the dielectric properties of asphalt and natural soil are  such that the phase of the voltage reflection coefficient is within a few degrees of  180°. This being the case, one can usually choose a combination of target and antenna  heights such that the wave reflected by the ground arrives at the target in phase with  the wave propagated directly from the antennas. 
 Thus the linear FM, or chirp, pulse­ compression waveform is a practical approximation to the theoretical doppler-tolerant  waveform. Differentiating, with respect to time, the argument of Eq. (11.55), the frequency of  the dopplcr-tolerant waveform is found to be 2rr.f5 T/(fo T -Bt). 
 Section 3presents simulation results. Section 4 discusses the results and the contributions of the proposed methods. 2. 
 SCALE WILL NOT BE EXCEEDED &OR EXAMPLE  WITH GAUSSIAN NOISE  A CREST FACTOR OF  SETS THE PEAK LEVEL AT THE  R LEVEL  D" ABOVE  THE RMS LEVEL  WITH A PROBABILITY OF  THAT THE FULL 
 Appl. Meteorol ., vol. 16, pp. 
 L. Schuler, “The modification of X and L band radar signals by monomolecular  sea slicks,” J. Geophys. 
 The residual path error is the error caused by delays in the circuitry and  transmission lines. Multipath signals also produce error. Figure 3.14 shows some of the  utiwanted signals that might occur in the FM altimeter.36.37 The wanted signal is shown by  the solid line. 
 Gossard and R. G. Strauch, Radar Observations of Clear Air and Clouds , Amsterdam:  Elsevier, 1983. 
 However, departure from this +12 +10 I +8 ‘6/L A“ /Y[\\ ‘‘%~/’ ‘8 -10 0.1 0.2 0.4 0.60.81.0 2 4 6810 20 I.fbandwithln Mc\sec FIG.25.-Signalt hreshold vs.i.fbandwidth forapulse duration oflpsec. Thesignal power ismeasured inunits ofthenoise power, .Y,,within aband 1Me/see wide, Inthese experiments thevideo bandwidth was10Mc/sPc, thesignal presentation time was3see, andthelength ofthepulse onthescreen ofthe.L.scope was1,7mm. value byafactor of2ineither direction increases theminimum discern- ible signal power byless than 1db. 
 TUNED  ITS BANDWIDTH WAS   -(Z   AND  A GAIN OF  D"  4HEORY SHOWS THAT THE BANDWIDTH OF A KLYSTRON CAN BE SIGNIFICANTLY INCREASED BY  INCREASING ITS CURRENT AND THUS ITS POWER !  -7 PEAK POWER KLYSTRON  FOR EXAMPLE  CAN HAVE AN  BANDWIDTH AS COMPARED TO A  K7 TUBE  WHICH MIGHT HAVE A  BANDWIDTH  AND A  K7 TUBE HAVING ONLY A  BANDWIDTH (IGH 
 17.13 itisassumed that thebasic pulse and thesine puke have been decoded and ~eparated sothat each isavailable ona. 1Bas,c pulse I%e pulse i ~--.J_7_7 ~–-.--–~ ,–––––--, Fl[pflopISwitchI W[de-pulSe I U I ‘+1Variable delay ] I-—— -–J L–gY:rY: 1 l___ –_J R [11SawloothDouble clamp,4+ Bsin.9 generators T L T—(a) Slmpletracklng method Sne pulse SwitchE Basic pulse Mlsmaich B AVariable delayAFlop over Fl,pflopA+lls,n13 -@D i—1- (b)7 i Regenerahve track,ng method~cBasicpulse~ Sinepuke~ Point R Point s Point U Point V Point A Point B Po,nt D Point En A r-l Sine III %(II v3. ffi. 
 Another  application is to use either phase-or frequency-steering in a stationary linear array to  steer the beam in one angular coordinate, as for the GCA radar.  Pliase{requency planar array .. A two-dimensional (planar) phased array can utilize frequency  scanning to steer the beam in one angular coordinate and phase shifters to steer in the . 
 RANGE LOCATION CAN BE MORE ACCURATE THAN MONOSTATIC OR BISTATIC  CROSS 
 LIMITED CASES AND IS REPORTED ELSEWHERE   $OPPLER 
 A longitudinal, directly approaching or receding sea gives the largest value. A transverse, cross to the radar look direction, gives two peaks equal in height. By scanning over a radar's total potential coverage area and using the ratio of the two resonant doppler frequency sea responses, a map of sea principal direc- tion can be constructed.23'24 By inference, surface winds can be mapped. 
 DIMENSIONAL RECONSTRUCTION '02 DATA MAY BE CLASSIFIED AS ! 
 Brit. IRE, vol. 26,  pp. 
 H., D. D. Howard, and A. 
 Cook: Effects of Limiting on the Detectability of Partially Time Coincident  Pulse Compression Signals, IEEE Trans., vol. MIL-9, pp. 17-24, January, 1965. 
 It  is achieved by modulating t he pulse in the transmitter  so different  parts of the pulse become more discernable . The  actual time compression is accomplished by the radar  receiver.     Figure 6. 
 94, pp. 1520–1524, 1989. 43. 
 For a sinusoidal input, the output signal at the threshold of limiting is  v0 = Esin(w t) (6.23) ch06.indd   30 12/17/07   2:03:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 PIC  HIGH DIELECTRIC AND  HIGH LOSS  AND MAY  BE LAYERED 4HEREFORE  AN UNDERSTANDING OF  SOIL AND MATERIAL PROPAGATION CHARACTERISTICS IS IMPORTANT  AND THIS SECTION DESCRIBES THE KEY FEATURES OF THE PHYSICS OF PROPAGATION IN MATERIALS -AXWELLS EQUATIONS ARE THE FOUNDATION FOR THE CONSIDERATION OF THE PROPAGATION OF  ELECTROMAGNETIC WAVES )N FREE SPACE  THE MAGNETIC SUSCEPTIBILITY AND ELECTRIC PERMITTIVITY ARE CONSTANTS  THAT IS  THEY ARE INDEPENDENT OF FREQUENCY AND THE MEDIUM IS NOT DISPERSIVE )N A DIELECTRIC WITH A ZERO LOSS TANGENT  NO LOSSES DUE TO ATTENUATION ARE ENCOUNTERED  AND HENCE THERE IS NO CONSIDERATION OF THE ATTENUATION  WHICH OCCURS IN REAL DIELECTRIC MEDIA )F AN ALTERNATING ELECTRIC FIELD IS APPLIED TO A MATERIAL  THE INDIVIDUAL MOLECULES WILL  BE INDUCED TO ROTATE IN AN OSCILLATORY MANNER ABOUT AN AXIS THROUGH THEIR CENTERS  THE INERTIA OF THE MOLECULES PREVENTING THEM FROM RESPONDING INSTANTANEOUSLY 3IMILAR TRANSLATIONAL EFFECTS CAN OCCUR  4HE POLARIZATION PRODUCED BY AN APPLIED FIELD SUCH AS  A PROPAGATING RADAR WAVE  IS CLOSELY RELATED TO THE THERMAL MOBILITY OF THE MOLECULES AND IS  THEREFORE  STRONGLY TEMPERATURE DEPENDENT .OTE THAT POLARIZATION IN THIS CONTEXT IS DIFFERENT FROM THE POLARIZATION  OF %- WAVES )N GENERAL  THE RELAXATION TIME WHICH  MAY BE EXPRESSED AS A RELAXATION FREQUENCY  DEPENDS ON ACTIVATION ENERGY  THE NATURAL FREQUENCY OF OSCILLATION OF THE POLARIZED PARTICLES  AND ON TEMPERATURE 2ELAXATION FREQUENCIES VARY WIDELY BETWEEN DIFFERENT MATERIALS &OR EXAMPLE  MAXIMUM ABSORPTION OCCURS AT VERY LOW FREQUENCIES  IN ICE   (Z    WHEREAS IT TAKES PLACE IN THE MICROWAVE REGION IN WATER  (Zn (Z  THUS  THE  EFFECTS OF THIS PHENOMENON CAN HAVE A DIRECT BEARING UPON THE DIELECTRIC PROPERTIES OF MATERIALS AT THE FREQUENCIES EMPLOYED BY '02S  ESPECIALLY IF MOISTURE IS PRESENT WITHIN A MATERIAL 4HERE ARE A NUMBER OF OTHER MECHANISMS  WHICH CAUSE A SEPARA 
 STAGE LIMITER WILL EXHIBIT A CONSTANT  OUTPUT OVER A WIDE RANGE OF INPUT SIGNAL AMPLITUDES /NE CAUSE IS APPARENT IF ONE CONSIDERS THE EFFECT OF A SINGLE 
 34–46, September 1985. 24. S. 
 ZERO IN THE INTEGRAL ONLY FOR THE TIME IT ILLU 
 J., and D. S. Zrni£: "Doppler Radar and Weather Observations," Aca- demic Press, Orlando, FIa., 1984. 
 SEC. 58] F-M RANGE-MEASCRING SYSTE.\! 143 number ofrange intervals that can bedistinguished isessentially the same asthe number ofsidebands added. Asystem ofthis type will bedescribed later. 
 A Surface Acoustic Wave (SAW)  device consists of an input transducer and an output transducer mounted on a piezo - electric substrate. These transducers are usually implemented as interdigital devices  that consist of a metal film deposited on the surface of the acoustic medium. This metal  film is made of fingers (see Figure 8.7) that dictate the frequency characteristic of the  unit. 
 band, radar cross section measurements of a variety of insects rangofrom 0.02 to  9.6 cm2 with longitudinal polarization, and from 0.01 to 0.96 cm2 for transverse  polarization.'0' A desert locust'02 or a honeybeer0' might have a cross section of about 1 cm2  at X band. At S band the cross section of a cabbage looper moth is about 2 x 10- ' cm2, and  for an adult field cricket it is 0.1 cm2.'03 The cross section of insects below .Y band is  approximately proportional to the fourtli-power of the freq~iency.'~~.'"~ Appreciable echoes  are obtained only when insect body lengths are greater than a third of the radar wavelength.  Insects observed broadside have echoes 10 to 1000 times greater than when viewed  end-on.' "  Heavy angel activity can be readily produced by insect concentrations that would scarcely  cause visual awareness. 
 Multiple Hypothesis Algorithms  The most sophisticated algorithms are multiple  hypothesis algorithms in which all (or many) possible tracks are formed and updated  with each possible detection.66,67,68 In Table 7.6, track no. 1 would become three  tracks (or hypotheses), corresponding to updating with detection no. 8, detection  no. 
 3. The signal-to-noise ratio is inversely proportional to the wavelength. 4. 
 M.: Some Applications of Detection Theory to Radar, IRE Natl. Conu. Record, vol. 
 I. Abramovich, S. J. 
 Kdp is an especially important parameter when the radar is confronted  with typical contaminants as beam blockage, ground clutter domination, and calibra - tion errors. Furthermore, Ryzhkov and Zrnic126 have shown that Kdp-based rainfall  measurements are less dependent on the unknown and variable drop-size distribu - tion (DSD) than power-based measurements. Furthermore, other inferences from the  ch19.indd   27 12/20/07   5:39:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 For very-short-range targets, a sufficiently good estimate of target height is given by the flat-earth approximation: hT= ha + R7 sin 6r (20.1) where ha is the radar antenna height, RT is the measured target range, 6r is the measured or estimated target elevation angle, and /zris the estimated target height. Spherical Earth: Parabolic Approximation. A somewhat better approx- imation to target height which models the earth's curvature as parabolic in range can be derived by reference to Fig. 
 SURFACE ICE )N WIN 
 At the septum it becomes the TE20 mode, which propagates to the horn aperture and uses the full width of the horn as desired. The TE20 mode has zero E field in the center of the waveguide where the septum is located and is unaffected by the septum. The AN/FPS-16 radar feed used two retracted septum horns illustrated in Fig. 
 Electronics Tech.  Rept. 186, Feb. 
 16, pp. 337-419, July, 1937.  4. 
 E. Fay: "Linear Ferrite Devices for Microwave Application." Academic  Press. New York, 1968. 
 However, this may not always be true. Propeller-driven aircraft produce  modulation components at the blade frequency and harmonics thereof and can cause a sub-  stantial increase in the spectral energy density at certain frequencies. it has been found exper-  imentally that the tracking accuracy of radars operating with pulse repetition frequencies from  1000 to 4000 Hz and a lobing or scan rate one-quarter of tlie prf arc not limited by ccho  amplitude fluct~ations.~~  The percentage modulation of the echo signal due to cross-section aniplitude tluctilatio~is  is independent of range if AGC is used. 
 This clutter is generally much smaller than the main-beam clutter but covers much more of the frequency domain. The sidelobe clutter from the ground directly below the radar, the altitude line, is frequently large owing to a high reflection coefficient at steep grazing angles, the large geometric area, and the short range. Range performance is degraded for targets in the sidelobe clutter region wherever the clutter is near or above the receiver noise level. 
 AREA RATIO  OR %P"A  IS MAXIMIZED WHERE POSSIBLE 'ENERALLY  HIGHER 
 L. Friedlander and L. J. 
 MODE SIGNALS  SIDE BY SIDE   ARRIVING AT THE SEPTUM OF &IGURE  OUT OF PHASE !T THE SEPTUM  IT BECOMES THE 4%  MODE  WHICH PROPAGATES TO THE HORN APERTURE AND USES THE FULL WIDTH OF THE HORN AS DESIRED 4HE 4%  MODE HAS ZERO  % FIELD IN THE CENTER OF THE WAVEGUIDE WHERE THE  SEPTUM IS LOCATED AND IS UNAFFECTED BY THE SEPTUM ! FURTHER STEP IN FEED DEVELOPMENT IS THE FOUR 
 TARGET RANGE M   22   2ECEIVER 
 54. R. E. 
 FREQUENCY RADAR HAS POOR ANGULAR RESOLUTION 4RACKING 2ADARS  4RACKING RADARS PROVIDE GOOD RESOLUTION AND PRECISE MEASURE 
 80  In the early 1920s, millimeter-wave research was reported in the United States, Germany, and  Russia, with wavelengths as short as 0.22 mm.81 Although many important applications of the  microwave region have been developed, there has been almost no comparable activity in the  millimeter-wave region. There are many possible reasons for this lack of activity, including  lack of adequate millimeter-wave components, small antenna sizes, and difficult MTI. But  the most restricting of all has been the relatively large attenuations experienced when propa­ gating through the clear atmosphere, as well as the added attenuation during rain. 
 49.lliahy.F.T..1'.F.Rush.andP. P.Ratlivala: RadarResponse toVegetation II:8-18GHzBand. IEEETrans,vol.AP-2J,pr.608618. 
 94. Sensors 2019 ,19, 1649 Figure 5. Range and Azimuth references to be used in the focusing procedure. 
 325 339. 1947.  9. 
 Therefore, the TEC derived from averaging the whole PolSAR TEC image is countable. One should note that the average window used to reduce the speckle noise in Equation (2) was set to be 21 ×41 pixels. Actually, we tested window sizes from 10 ×10 to 200 ×200, and the changes between the resulting TECs were within 0.01 TECU. 
 This increase presents additional transmitter circuit prob- lems, and reduces the gain inthe amplifier stages. Inthe receiver, the greater bandwidth admits more interference inaddition tocomplicating thereceiver design. The most important aspects oftherelative virtues ofthetwo types of modulation arise, however, inconnection with the consideration of particular types ofsignals and interference. 
 One method of accounting for a fluctuating cross section in the radar equation is to select  a lower bound, that is, a value of cross section that is exceeded some specified (large) fraction  of time. The fraction of time that the actual cross section exceeds the selected value would he  close to unity (0.95 or 0.99 being typical). For all practical purposes the value selected is a  minimum and the target will always present a cross section greater than that selected. 
  
 Two common geometrical forms of array antennas of interest in radar are the  liticar array arld the planar array. A litlcur trrruj1 consists of elements arranged in a straight line  in one dimensiot~. A plcrr~or. 
 MERCIAL CRAFT UNDER  GT #LASS " IS FOR RECREATIONAL CRAFT AND #LASS # IS FOR SMALL RECREATIONAL CRAFT 4HE MAIN PERFORMANCE REQUIREMENTS ARE DETAILED IN 4ABLE . ÓÓ°£ä  2!$!2 (!.$"//+  ÓÓ°{Ê / 
 46-49, October, 1973.  133. Kummer. 
         D"SM . Óä°xä  2!$!2 (!.$"//+  4HIS IS A QUITE LOW 2#3 AT  (&  INDICATING THAT WHEN CONDITIONS ARE FAVORABLE  VERY  SMALL TARGETS ARE POTENTIALLY DETECTABLE 4HE EXPERIMENTAL DEMONSTRATION THAT  ON OCCASION  THE ENVIRONMENT SUPPORTS   ^ D" SUB 
 DECM is also divided  into transponders  and repeaters .3 Transponders generate noncoherent signals that emu - late the temporal characteristics of the actual radar return. Repeaters generate coherent  returns that attempt to emulate the amplitude, frequency, and temporal characteristics of  the actual radar return. Repeaters usually require some form of memory for microwave  signals to allow anticipatory returns to be generated; this is usually implemented by  using a microwave acoustic memory or a digital RF memory (DRFM).3 In a DRFM system, the input RF signal is generally first down-shifted in frequency  and then sampled with a high-speed analogue-to-digital converter (ADC). 
 FED ANTENNA HAS POORER PERFORMANCE THAN A PARALLEL FEED SINCE EACH HALF SCANS (OWEVER  AT  n SCAN THE COMPENSATION ON ONE 
 In our processing, it was very time consuming to carry out a point-wise genetic search algorithm, so the parameter results for the whole area of Lungui Road and its surroundings were not obtained. Our future study will be focused on the parameter estimation algorithm, in order to improve e ﬃciency and accuracy. Author Contributions: X.X. 
 329–333. 15. F. 
 H.: The Absorption of Microwaves by Oxygen, Phys. Rev., vol. 71, pp. 
 CONTROLLING VARIABLES PLOTTED AS A FUNCTION OF  RANGE FOR *ANUARY   54#  33.  . 
 2ADAR ./342!$!-53 v  )%%% 2ADAR #ONFERENCE   3YRACUSE  .9  -AY  !LSO REPRINTED IN  )%%% !%3 3YSTEMS -AGAZINE   VOL   NO    PP n  /CTOBER   :HOU 7ENYU AND -AO 8U   h"ISTATIC &-#7 /4( 
 Skolnik (ed.), McGraw-Hill Book  Co .. New York, 1970.  40. 
 ALARM PROBLEM "OTH ADAPTIVE THRESHOLDING AND NONPARAMETRIC DETECTORS ARE BASED ON THE ASSUMPTION THAT HOMO 
 All rights reserved. Except as permitted under the United States Copyright  Act of 1976, no part of this publication may be reproduced or distributed in  any form or by any means, or stored in a data base or retrieval system,  without the prior written permission of the publisher.  l 2 3 4 5 6 7 8 9 2 0 BJE 9 8 7 6 5 4  This book was set in Times Roman. 
 PULSE CANCELER RESIDUE AND B   IMPROVEMENT FACTOR FOR HARD 
 ING AT A 02& OF  (Z 4HUS  THE BREAK FREQUENCY IS   r     (Z C  4HIRD   THE RECEIVER PASSBAND IS ASSUMED TO EXTEND FROM  
 For satellite targets the separation might be hundreds or even thousands of  miles. A distinction is made between radars with closely spaced antennas and radars with  widely spaced antennas because the former resemble the conventional monostatic radar more  than the type of bistatic radar to be discussed here.  Description. 
 Figure 21.36  shows a radar image taken from an altitude of 400 meters above the Yuma desert.   The radar operated at a depression angle of 45°and achieved a nominal resolution of  80 cm. It was capable of detecting metal AT mines of 30-cm diameter buried at a depth  of 15–30 cm in a soil of conductivity 8–10 mmhos/m. 
 1339.-Synchronization of delayed sweep with precision range index. cuits, since itensures that the marker will always appear onthesweep regardless ofthesetting ofthetwo knobs. Adiscrete setofpulses isfrequently used toprovide astepwise sweep delay. 
 7:.  may be found from a straightforward application of Eq. (9.10); therefore ' = K + (La, - 1)Kt + (Lrr - l)T,tLat + T,e LrfLAt (12.16)  Note that T,, T,,, and T,[ are actual temperatures while T, and T,, are effective noisc:  temperatures. 
 Part B shows energy being reﬂected from the near target, while theleading edge of the transmitted pulse continues toward the far target. In partC, 1/2microsecond later, the transmitted pulse is just striking the far target; theechofromtheneartargethastraveled164yardsbacktowardtheantenna.The reﬂection process at the near target is only half completed. In part Dechoes are traveling back toward the antenna from both targets. 
 STANT OVER THE ILLUMINATED AREA  BUT SUCH AN APPROXIMATION TO %Q  SHOULD BE  ATTEMPTED ONLY AFTER CHECKING ITS VALIDITY FOR A PARTICULAR PROBLEM )F THE RESULT OF APPLYING THE TECHNIQUE OF %Q  TO A SET OF MEASUREMENTS INDI 
 THE RADAR TRANSMITTER  10.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 gain-bandwidth product, this form of structure can produce a tube of much shorter  length so that there can be substantial savings in magnet weight and power. Symons,22  the inventor of the clustered-cavity klystron, states that one of these wide bandwidth  tubes can be used to replace the two narrower-band klystrons in the AWACS radar.  When each of the two narrow-band tubes is replaced by a wideband clustered-cavity  tube, redundant operation can be provided with higher reliability and without a large  weight penalty because either of these clustered-cavity klystrons provide full opera - tional capability similar to the redundancy commonly employed in FAA air-traffic  control radars. 
   IT IS BY NO MEANS A VIABLE APPROACH FOR REDUCING THE ECHOES FROM WING LEADING EDGES )NDEED  THE DESIGNERS OF THE " 
 ART IN AIRBORNE SEARCH OR SURVEILLANCE RADARS  %XCEPT FOR THE MENTION OF A FEW BASIC CONCEPTS  THIS CHAPTER DOES NOT DELVE INTO THE EXTENSIVE SUBJECTS OF ORBITOLOGY  IMPLEMENTATION OF SPACE 
 TO 
 1997 ,8, 98–113. [ CrossRef ] 29. Chen, S.; Wang, H.; Xu, F.; Jin, Y.Q. 
 A. Leusenko, V . N. 
 dimension with spacing d and M = number in  0,, dimension.  Beam steering. The beam of an array antenna may be steered rapidly in space without moving  large mechanical masses by properly varying the phase of the signals applied to each element. 
 The ambiguity diagram has been used to assess the properties of the transmitted  waveform as regards its target resolution, measurement accuracy, ambiguity, and response to  clutter.  Properties of the ambiguity diagram. The function I x(TR, fd) 12 has the following properties:  Maximum value of I x(TR, !J) 12 = I x(O, 0) 12 = (2£)2 ( 11.50)  lx(-TR, -fd)l2 = lx(TR,fd) 12 (11.51)  I x(TR, 0) 12 = If u(t)u*(t + TR) dt 12  (11.52)  I x(O, fd) 12 = I J u2(t )e1i,,1J' dt I 2 ( 11.53)  ( l l.54)  The first equation given above, Eq. 
 QUENCY AGILITY IS EMPLOYED   ONE MUST #&!2 EACH PULSE AND THEN INTEGRATE 7HILE THE BINARY INTEGRATOR PERFORMS THIS TYPE OF #&!2 ACTION  ANALYSIS   HAS VERIFIED THAT THE  RATIO DETECTOR SHOWN IN &IGURE  IS A BETTER DETECTOR 4HE RATIO DETECTOR SUMS SIGNAL 
 Most of the work on confornial arrays has been with the cylinder. Even though it niay be  a rclat~vely si~iiplc sliape coriipared to the others tner~tioned above or to the generaliled  noriplanar surface, the properties of the cylindrical array are not as suitable in general as those  of the planar array. In a cylindrical array, the radiation pattern cannot be separated into ari  elenierit factor arid an array factor as in planar array theory. 
 (20.11). In the stacked-beam radar, the transmit beam must be designed to cover all the beams within the stack and is therefore relatively wide in elevation beamwidth compared with that of a receive beam in the stack. A good approxi- mation is that it is isotropic in elevation and thus is not a factor in the fundamen- tal accuracy performance. 
 TRACK RESOLUTIONS OF  KM AND  KM  RESPECTIVELY 4HE LARGER ALONG 
 2, pp. 13- 14, October, 1959.  51. 
 ANGLE OCEAN MICROWAVE  BACKSCATTER AND ITS RELATION TO SEA SPIKES v )%%% 0'!0  VOL   NO   n    * # 7EST  * - 3TURM  AND ! 
 From this the atmospheric absorption noise can be computed directly.   6.4 System Noise Temperature   When calculating the system noise temperature all noise contributions, which are fed into the  input stages of the antenna, must be considered according to power and without any phase  correlation.  Generally the contributions for system noise temperature can be divided into three groups: . 
 (13.1) is (n/4)ROBR4, sin 4, where 4 = grazing angle. The factor n/4  accounts for the elliptical shape of the area. Substituting A, into Eq. 
 RCS is related to the physical characteristics of the target and the parameters of the electromagnetic wave. Therefore, if the curve of the RCS amplitude versus the aspect angle (hereafter referred to as RCS curve) is known, we can see the scattering behavior of the target and judge whether a target is isotropic or anisotropic. We can simulate the RCS curve for the selected shapes. 
 N. Bramley and S. M. 
  
 Compensation-Pattern Selection. Selection of the compensation pattern depends on the level of system performance required, the type of MTI filtering used, the platform velocity, scan rate, and the characteristics required by normal radar parameters such as resolution, distortion, gain, sidelobes, etc. For instance, an exponential pattern and its corresponding difference pattern are excellent for single-delay-cancellation DPCA but are unsatisfactory when double-delay cancellation is used. 
 Target Visibility .—There aretwo problems tobediscussed in this section. The first has todowith the visibility ofmoving targets when they areclear oftheclutter; itincludes consideration ofundesirable targets, like clouds, aswell asdesirable targets such asaircraft. The second problem isconcerned with the visibility ofmoving targets that occur atthesame range and azimuth asground clutter. 
 21. Fano, R. M.: Signal-to-noise Ratios in Correlation Detectors, MIT Research Lab. 
 RECEIVE PAIR )N CONTRAST  WHEN THE TARGET IS LOCATED SOME DISTANCE FROM THE THREE SITES   @ IS REDUCED &OR EXAMPLE  WHEN   @     R DR     AND  RCR    4HUS  THE DOWN 
 Staprans, A., E. W. McCune, and J. 
 Compressed sensing. IEEE T rans. Inf. 
 ,  " "9 %7 IS DEFINED AS A MILITARY ACTION INVOLVING THE USE OF %- ENERGY TO DETERMINE  EXPLOIT  REDUCE  OR PREVENT RADAR USE OF THE %- SPECTRUM n 4HE OPERATIONAL EMPLOY 
 Several types offilter have been tried; thesimplest isthefast time constant (FTC) circuit shown in Fig. 12.14.. SEC. 
 DISTRIBUTED WITH R    AFTER 6 ' (ANSEN Ú )%%%   &)'52%  $ETECTION PERFORMANCE OF THE ANALOG MOVING 
 PULSE SIGNAL 
   42!#+).' 2!$!2   °Ó£ 4HE MAJOR DIFFERENCE BETWEEN NOISE AND A TARGET ECHO IS THAT NOISE SPIKES EXCEEDING THE  THRESHOLD ARE RANDOM  BUT IF A TARGET IS PRESENT  THE THRESHOLD CROSSINGS ARE MORE REGULAR /NE TYPICAL SYSTEM SIMPLY COUNTS THE NUMBER OF THRESHOLD CROSSINGS OVER THE INTEGRATION PERIOD  AND IF CROSSINGS OCCUR FOR MORE THAN HALF THE NUMBER OF TIMES THAT THE RADAR HAS TRANSMITTED  A TARGET IS INDICATED AS BEING PRESENT )F THE RADAR PULSE REPETITION FREQUENCY IS  (Z AND THE INTEGRATION TIME  IS  S  THE RADAR WILL OBS ERVE  THRESHOLD CROSSINGS  IF THERE IS A STRONG AND STEADY TARGET (OWEVER  BECAUSE THE ECHO FROM A WEAK TARGET COMBINED WITH NOISE MAY NOT ALWAYS CROSS THE THRESHOLD  A LIMIT MAY BE SET  SUCH AS  CROSSINGS  THAT MUST OCCUR DURING THE INTEGRATION PERIOD FOR A DECISION THAT A TARGET IS PRESENT &OR EXAMPLE  PERFORMANCE ON A NON 
 However, ithastwo princi- pallimitations inaddition tothe restriction onoff-centering mentioned above: themechanical switching limits the scanning rates atwhich itcan beused, and some distortion isintroduced on“long” sweeps (more than 50miles) bythelow but appreciable resistance oftherectifiers. Ifthis resistance were constant, the only effect would beadroop caused by inadequate low-frequency response. This droop could easily beover- come byshaping the primary waveform, but unfortunately the rectifier resistance isnonlinear, being much larger atvery lowthan atintermediate orhigh currents. 
 The sum D, + D, locates the target somewhere on the surface of a prolate spheroid (an ellipse  rotated about its major axis) whose two foci are at the location of the transmitter and receiver.  To further localize the target position the scattered-signal angle of arrival is required at  the receiver. The intersection of the ray defined by the angle of arrival and the surface of  the prolate spheroid determines tbe position of the target in space. 
 (Coldrirsy b;oodpeur Atlrosp~cr alud l.iltot~ ,Art  )ice.) (h) A bend in the Huron river (center)just east of Ann Arbor, Michigan. Note foolball stadlur  h lights) top left center, and large orchard in upper righl cenler. South is in the up direclio  olution is 5 fi (1.5 rn) in azimlith and 7 ft (2.1 m) in range. 
 The control box can also beprovided with agear train that actuates amechanism showing latitude and longitude directly, inaddition toshowing the departure from thelast fix. Inacarefully made installation, the cumulative error ofthis instrument amounts to only ~percent ofthetotal distance traveled from thepoint ofdeparture. Ground-position Indicator, GPI.—Although the device just described aids inperforming dead reckoning, and tothis extent assists inradar navigation, itisconvenient topresent the results ofthe dead reckoning directly onthe radar scope. 
  
  AND %23 
 Radar System Engineering  Chapter 6 – Radar Receiver Noise and Target Detection  35     € BN=H(f)2df −∞∞ ∫ H(f0)2 (6.12)  € H(f)=IFfrequency channel  &  € H(f0)=max oftheIFfilter curve .  In  € BN it is considered that the noise through the HF and IF circuitry (especially the filter) will  be weighted according to the frequency.  Only for rectangular filters is B N identical to the IF  bandwidth B IF. 
 Echoesfromastorm,for example, mightmaskorconfuse theechoesfromtargetslocatedatthesamerangeand azimuth. Ontheotherhand,radarreturnfromrain,snow,orhailisofconsiderable impor­ tanceinmeteorological research andweatherprediction. Radarmaybeusedtogiveanup-to­ datepatternofprecipitation intheareaaroundtheradar.Itisasimpleandinexpensive gauge formeasuring theprecipitation overrelatively large expanses. 
 21 2J. 1975. pp. 
 This loss may be  included in the receive system noise figure or system temperature value. IF Matched Filter Loss.  The matched filter for a pulse doppler waveform includes  the analog IF matched filter in the receiver and any subsequent digital integration of  A/D samples to match the duration of the transmit pulse. 
 Nominal PRF is 3250 Hz ± 450 Hz. Data rates span 142 Mbits/s to 1478 Mbits/s,  depending on mode. The on-orbit mass of the spacecraft will be ∼1750 kg, of which  the SAR payload (including the antenna) claims ∼950 kg. 
 WAY ANTENNA SIDELOBES ALONG WITH THE COMBINATION OF TECHNIQUES DISCUSSED IN 3ECTION   SUCH AS GUARD CHANNEL BLANKING AND POSTDETECTION 34#  ARE USED TO MITIGATE SIDELOBE CLUTTER DISCRETE FALSE ALARMS -273 ALSO USES PULSE COMPRESSION TO DECREASE THE AMOUNT OF SIDELOBE CLUTTER THAT  TARGETS MUST COMPETE WITH 4HE LOWER 02& REDUCES ECLIPSING AND  THE AMOUNT OF CLUT 
 9.5, which shows two dipoles excited bytheradiation field from the~-byl-in. waveguide transmission line. The dipoles aresoadjusted inlength and position that their com- bined effect istodirect theradiation back within acone surrounding the line without reflecting radiation into the waveguide. 
 TION 4HE COMPRESSED PULSE RESPONSE AT THE OUTPUT OF THE WEIGHTING FILTER IS GIVEN BY   Y T "T & "T M "TOM MN   ; 
  
 %23 
 OPERATIVE RADAR TRANSMITTERS v 2ADIO %LECTRON %NG  VOL   PP n  &EBRUARY   . &REEDMAN  h"ISTATIC RADAR SYSTEM CONFIGURATION AND EVALUATION v 2AYTHEON #OMPANY   )NDEPEND $EV 0ROJ $ 
 The achievement of a larger area coverage rate is another but less likely motivation. A great deal of flexibility is possible. The multiple beams may be arranged in the azimuth direc- tion or the range direction, or both. 
 A discontinuous waveform can result in peaks in the ambiguity diagram at other values  of TR , fd. The pulse train (Fig. 11.11 or 11.13h) is an example. 
 82. Dillard, G. M.: Mean-Level Detection Utilizing a Digital First-Order Recursive Filter, IEEE Tran-r ,  vol. 
 That is, a decimate-by-16 filter would be composed of a decimate- by-8 CIC filter followed by a decimate-by-2 FIR filter. The FIR filter can be tailored to  remove the undesired residual components before the final decimation. The FIR filter  can also be configured to compensate for the droop in the passband response. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars.  SPACE-BASED REMOTE SENSING RADARS  18.396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 surface reflection.70 The ocean’s surface has a significant wave height of less than  20 m or so. 
   PP n    # ( "IDWELL  $ - 'RAGG  AND # 3 7ILLIAMS h2ADAR RETURN FROM THE VERTICAL FOR GROUND AND  WATER SURFACE v 3ANDIA #ORPORATION  !LBUQUERQUE  .-    9 3 +IM  2 + -OORE  2 ' /NSTOTT  AND 3 0 'OGINENI   h4OWARDS IDENTIFICATION OF OPTIMUM  RADAR PARAMETERS FOR SEA 
 Therefore, compared with linear scanning GBSAR, ArcSAR has larger ﬁeld of view. Although the feasibility of ArcSAR has been veriﬁed in recent years, its imaging algorithm still presents diﬃculties. The imaging accuracy of ArcSAR is a ﬀected by terrain ﬂuctuation. 
   %,%#42/.)# #/5.4%2 
 The principle of ADT was demonstrated in the  early 1950s, using vacuum-tube technology, as part ·of the United States Air Force's SAGE  air-defense system developed by MIT Lincoln Laporatory. In this form ADT was physically  large, expensive, and difficult to maintain. The commercial availability in the late 1960s of the  solid-state minicomputer, however, permitted ADT to be relatively inexpensive, reliable, and  of small size so that it can be used with almost any surveillance radar that requires it. 
 (This is a collection  of early classic papers concerning SAR.) 16. D. C. 
 Adaptive Speckle Filters and Scene Heterogeneity. IEEE T rans. Geosci. 
 "AND -ONOPULSE  $UAL 
   4HE 3!2 ABOARD THE *APANESE %ARTH 2ESOURCES 3ATELLITE  * 
 175 Hoekman et al., “Biophysical forest type characterization in the Columbian Amazon by airborne  polarimetric SAR,” IEEE Trans. on Geosc. and Remote Sensing , vol. 
 In one  type of cylindrical constrained lens with the E field parallel to the plates, a I" beam coi~ld bc  scauiled over a 100" sector by positioning the line feed." The lcris was 72 wavelengths in sire,  had an /;ID = 1.5, and operated at a wavelength of 1.25 cm.  Luneburg lens. Workers in the field of optics have from time to timc devised lenses in whicl~  the index of refraction varied in some prescribed manner within the lens. 
 OF 
 The increased calculation times by applying the proposed approach can be nearly ignored in practical application. On the basis of the space storage efﬁciency, the approach proposed in the paper needs to occupy more memory space compared to that needed by applying the independent CS approach of single-channel, but it can be effectively released through parallelization. 168. 
 @2 THE FACTOR THAT MULTI 
 FIGURE 3. 20 Optimized DPCA phase compensation ch03.indd   21 12/15/07   6:03:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars.  SPACE-BASED REMOTE SENSING RADARS  18.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 ScanSAR coverage (8-m resolution, 40-km swath, to 20-m resolution, 100-km swath,  incidence-dependent) is executed by sequential selection of the appropriate feeds. 
 POWER BEAM STEERING /N RECEIVE  EACH DUPLEXER OUTPUT IS SENT TO ITS OWN DIGITAL RECEIVER 4HE DIGITAL  RECEIVER OUTPUTS ARE PASSED THROUGH 02) DELAYS TO YIELD TEMPORALLY DISPLACED DATA  SAMPLES ! FULL COMPLEMENT OF ELEMENTS AND TIME 
 5 Comparison of compressed-pulse shapes for three frequency-domain  weighting functions ch08.indd   7 12/20/07   12:49:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 
 The quantity nisproportional tobeamwidth and PRF, and inversely proportional toscanning rate. Ithasthevalue 120foraPRF of720with a1°beam rotating at1rpm. Although this setofconstants satisfies the condition above, the scanning rate istoo slow formany purposes. 
 Elliot. R. S.: Mechanical arid Electrical Tolerances for Two-dimensional Scanning Antenna Arrays,  IRE 7'rt111s., vol. 
 22, 1973.  150. Gabriel. 
 FORWARD -4) RADAR  FILTERS v 0ROC )%%%  VOL   PP n  *ANUARY   7 $ 7HITE AND ! % 2UVIN  h2ECENT ADVANCES IN THE SYNTHESIS OF COMB FILTERS v IN  )2% .AT  #ONV 2EC VOL   PT   .EW 9ORK  .9    PP n  2 ( &LETCHER AND $ 7 "URLAGE  h)MPROVED -4) PERFORMANCE FOR PHASED ARRAY IN SEVERE CLUTTER  ENVIRONMENTS v IN )%%% #ONF 0UBL     PP n   ! 6 /PPENHEIM AND 2 7 3CHAFER   $IGITAL 3IGNAL 0ROCESSING  %NGLEWOOD #LIFFS  .* 0RENTICE 
 DEFINED GEOMETRICAL BOUNDARIES 4HE SITUATION IS MORE DIFFICULT WITH STRATIFIED LAYERS AND  OF COURSE  ANISOTROPIC MATERIALS 7HEN A RECONSTRUCTED IMAGE OF THE BURIED OBJECT IS CREATED  WHETHER AS A " 
 DAY CONTRASTS  SUCH AS AVAILABLE FREQUENCIES AND DIFFERENCE IN NOISE LEVEL  FOR THE SAME RANGE  ARE EVIDENT !LSO NOTE THAT AT NIGHT THE  
 FLAT SEA  A PULSE 
 Theproblem ofdesigning awaveform toachievedetec­ tionmaybeconsidered independently oftherequirements ofaccuracy, ambiguity, resolution, andclutterrejection. Awaveform satisfies therequirements ofdetection ifitsenergyis sufficiently largeandifthereceiver isdesigned inanoptimum manner, suchasamatched-filter receiver. Waveform shapeisimportant onlyasitaffectsthepractical designofthematched filter.Theabilityofaparticular waveform tosatisfytherequirements ofaccuracy, ambiguity, resolution, andclutterrejection maybequalitatively determined fromanexamination ofthe ambiguity diagram. 
 Convective cells, which are also called thermals, are the mechanism by which birds and  gliders soar. When the surface of the earth is heated sufficiently so that the air becomes hotter  than its surroundings, the buoyancy of the heated air will cause it to rise. If the source of heat is  fixed, the rise of buoyant air is called a thermal plume. 
 [CrossRef ] 14. Osher, S.; Feng, R.; Jiechao, X.; Yuan, Y.; Wotao, Y. Sparse recovery via differential inclusions. 
 Because of the variable dwell time  the anteona beam-positioning system must usually be a phased-array antenna and the data  processing must be digital. Thus if full benefit is to be had from the Sequential Observer in  radar, only one or a few independent decisions per beam position should be made. It might be  employed when only a single "guard-band" is desired for detecting targets within a selected  range interval, a not too usual application. 
 Merriman, R. H., and J. W. 
 Computational Complexity The running time of independent CS approach of traditional single-channel depends on step (2). Its computing cost is O(LtendNsPQ), wherein, the tendis the times of algorithm iterative circulation, and the Nsis the signal sampling times. The proposed approach has higher calculation efﬁciency and is only added with O(LtendPQ)times of addition calculation compared to independent CS approach of single-channel. 
 Ifthere isaload greater than normal causing the output voltage todrop, the manual rheostat will have tobeadjusted. However, with the motor-generator setacting asanelectromechanical flywheel totake uptransient fluctuations inthe ship’s power supply, operation isreasonably steady and satisfactory.. EXAMPLES BY R.G.CHAPTER 15 OF RADAR SYSTEM DESIGN HERB AND R.L.SINSHEIMER , 16.1. 
 The main bearing ofthe mount isaroller-ring bearing, defining the vertical axis ofthepedestal. Ontheturntable aremounted theantenna and the elevation drive, consisting ofmotor, gear reduction, crank, and connecting rod. The turntable also supports thepressurized modulator and itscontrols, the pressurized r-fhead, and the power supply for the receiver. 
 ITER IS PROVIDED TO PREVENT THE RESIDUE FROM STRONG CLUTTER FROM EXCEEDING THE THRESHOLD 7ITHOUT THE SECOND LIMITER  A STRONG 
 SEC. 6.12] HEIGHT-FINDING WITHAFREE-SPACE BEAM 191 lobes arenot objectionable inthis antenna, itdisplays considerable fre- quency sensitivity. Astanding-wave voltage ratio of1.33 (Chap. 
 The bright band is due to changes in snow falling through the freezing level. 71 At the  onset of melting the snow changes from flat or needle-shaped particles which scatter feebly to  similarly shaped particles which, owing to a water coating, scatter relatively strongly. As  melting progresses, the particles lose their extreme shapes, and their velocity of fall increases  causing a decrease in the number of ·particles per unit volume and a reduction in the  backscatter.. 
 Thediscussion inthischapter, forthe mostpart,isbasedontheMTIradar,butmuchofwhatappliestoMTIcanbeextended to pulsedoppler radaraswell. MTIisanecessity inhigh-quality air-surveillance radarsthatoperateinthepresence of clutter.Itsdesignismorechallenging thanthatofasimplepulseradarorasimpleCWradar. AnMTIcapability addstoaradar'scostandconlplexity andoftensystemdesigners must acceptcompromises theymightnotwishtomake.ThebasicMTIconcepts wereintroduced duringWorldWarII.andmostofthesignalprocessing theoryonwhichMTI(andpulse doppler) radardepends wasformulated duringthemid-1950s. 
 (From P. W. Hannan, Ref. 
 4. F. E. 
 UNIT TYPE DISPLAY IS MORE READILY UNDERSTOOD BY  THE TACTICAL RADAR OPERATOR LOOKING FOR AN OPTIMUM FLIGHT ALTITUDE FOR HIS ATTACK ÓÈ°{Ê -/  , Ê*,"*/" Ó 3TANDARD PROPAGATION MECHANISMS ARE THOSE MECHANISMS AND PROCESSES THAT OCCUR IN  THE PRESENCE OF A STANDARD ATMOSPHERE 4HESE PROPAGATION MECHANISMS ARE STANDARD REFRACTION  FREE 
 As the ground-based radar was known at that time as RDF 1, the new airborne radar was to be called RDF 2 and so this bistatic radar system wascalled RDF 1.5. Soon new transmitter valves were also becoming available and by early summer of 1937 an experimental ai rborne transmitter operating on a wavelength of 1.25 m was developed and successfully demonstrated on theHeyford. The receiver was now a superhet but used the same EMI television receiver as the IF ampli ﬁer. 
 DARDS OF GOOD MEASUREMENT PRACTICE HAVE BEEN RECOGNIZED FOR DECADES $EPENDING ON THE SIZE OF THE TEST OBJECT  THE FREQUENCIES TO BE USED  AND OTHER TEST REQUIREMENTS  MEASUREMENTS MAY BE MADE IN INDOOR TEST FACILITIES OR ON OUTDOOR RANGES "ECAUSE ONE IS SELDOM INTERESTED IN THE 2#3 OF AN OBJECT FOR ONLY ONE ASPECT ANGLE  ALL STATIC TEST RANGES USE TURNTABLES OR ROTATORS TO VARY THE TARGET ASPECT ANG LE !LTHOUGH THE PURPOSE  OF TESTING OFTEN GOVERNS HOW THE MEASUREMENTS WILL BE MADE  -ACK AND $YBDAL PRO 
 50. Kock, W. E.: Metal Lens Antennas, Proc. 
 The value of Z)0 thus found is the value to be used in the range equation [e.g., Eqs. (2.10) and (2.11)]. The process of finding the required value of D0 for use in the range equation is greatly facilitated by curves that relate the number of pulses integrated to D0 with Pfa and Pd as parameters. 
 SEC.86] FREQUENCY CONSIDERATIONS 261 The most satisfactory presentation ofbeacon replies forpurposes of ordinary navigation isundoubtedly the PPI since itgives the whole situation ataglance inadirect way. The angular widths ofbeacon replies should belimited toafew degrees, ifpossible. For anairborne interrogator this suggests the use of3-cm orshorter wavelength; for systems having ground interrogators with large antenna arrays acon- siderably lower frequency can beused. 
 As the inner conductor rotates the wavelength in the line  varies, causing the beam to scan.  7.5 LENS ANTENNAS  The most common type of radar antenna is the parabolic reflector in one of its various forms.  The microwave paraboloid reflector is analogous to an automobile headlight or to a search­ light mirror. 
 PULSE FREQUENCY  CHANGES RESULT IN PHASE RUN 
 39. Stewart, C.H., and G. J. 
 The peak sidelobe of the chirp waveform is generally higher, but at a slight sacrifice in  signal-to-noise ratio it can be made low by means of weighting networks. The chirp waveforrn  is doppler-tolerant in that a single pulse-compression filter can be used, but it cannot provide  an independent range and doppler measurement. With moving targets, the phase-coded pulse  might require a bank of contiguous matched filters covering the expected range of doppler  frequencies. 
 The  phases and amplitudes of the individual signals might add to give a large total cross section, or  the relationships with one another might result in total cancellation. ln general, the behavior is  somewhere b~tween total reinforcement and total cancellation. If the separation between the  individual scattering objects is large compared with the wavelength-and this is usually true  for most radar applications-the phases of the individual signals at the radar receiver will vary  as the viewing aspect is changed and cause a scintillating echo. 
 Nengjing, “ECCM efficacy assessment in surveillance radar analysis and simulation,” IRS  ’98, Int. Radar Symp ., Munich, Germany, September 15–17, 1998, pp. 1415–1419. 
 The diffracted field is given by the formula:  Ee e ksX Ydi =Γiksπ π/ sin( )4 2b∓  (14.17) where Γ is a divergence factor, X and Y are diffraction coefficients, b is the angle  between the incident ray and the edge, and s is the distance to the observation point  from the point of diffraction. The difference of the two diffraction coefficients is  FIGURE 14.19  The Keller cone of diffracted rays ch14.indd   24 12/17/07   2:47:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 A 50-km  radar, however, will have 30-dB attenuation, which is usually intolerable. Thus long-range  radar is not likely at millimeter wavelengths under normal circumstances. Although the atten-  uation at ~nillirnetcr wavelengths is far greater than that at microwave wavelengths, the losses  iticurred in propagating ~~lillimeter wavelengths through fog, haze, and smoke is less than at  infrared or visible wavelengths. 
 Sensors 2020 ,20, 1851 The proposed procedure consists of a pre-processing step for denoising SAR amplitude, followed by the change detection step performed by running algorithms of unsupervised feature learning (K-SVD) and clustering (k-means). Moreover, an optical ﬂow algorithm is used for distinguishing changes related to actual target motions (correct detections) from those related to errors in image co-registration (false positives). The procedure was ﬁrst introduced, and then tested on datasets coming from both an airborne high-resolution X-band SAR, and the spaceborne medium resolution C-band ERS-2 mission. 
 02&  A NUM 
 2.8) with scan-to-scan fluctuations to a Swerling type 2  with pulse-to-pulse fluctuation. From 4 to 7 dB improvement in signal-to-noise ratio might be  achieved in the diplex mode as compared with the simplex mode.46  The ARSR-3 utilizes a klystron amplifier to achieve 5 MW peak power and 3.6 kW  average power. The receiver front-end is a low-noise transistor with 4 dB noise figure. 
 To improve the efficiency of TWTs (or klystrons), the use of depressed collectors16'32 has been developed to a remarkably successful degree. The use of multiple collector sections at intermediate voltages allows catching each spent electron at a voltage near optimum. Up to 10 collector sections have been used in some communications tubes, but 3 sections, as shown in Fig. 
 The development of digital radar technology and economical high-speed pro- cessors allows the use of dynamic space-time adaptive array processing,16 whereby a set of antenna patterns that displace the phase center of the array both along and orthogonal to the array are continually synthesized to maximize the signal-to-clutter ratio. Spatial adaptive array processing combines an array of sig- nals received at the same instant of time that are sampled at the different spatial locations corresponding to the antenna elements. Temporal adaptive array pro- cessing combines an array of signals received at the same spatial location (e.g., the output of a reflector antenna) that are sampled at different instances of time, such as several interpulse periods for an adaptive MTI. 
  
 23-26, January, 1960.  88. Bayliss, E.T.: Design of Monopulse Antenna Di/Terence Patterns with Low Sidelobcs. 
 £x°Ón  2!$!2 (!.$"//+  )N FORMULATION   SOMETIMES CALLED THE  SMALL 
 LEVEL RESOLUTION 4HE REFERENCED STUDY SHOWED THAT INTERPRETABILITY DEPENDS ON  6 SO TRADEOFFS BETWEEN THE THREE ELEMENTS OF  6 ARE POSSIBLE "EST RESULTS FOR A HUMAN  INTERPRETER OCCUR WHEN THREE INDEPENDENT SAMPLES OF THE FADING ARE AVERAGED )GNORING THIS FADING SPECKLE  CAN LEAD TO ERRONEOUS CONCLUSIONS ON THE SPATIAL RESOLUTION NEEDED FOR A GIVEN APPLICATION 3INGLE 
 B. Earnshaw, and D. Van De Kamp: The Colorado Wind Profiling Network, J. 
 BAND TRANSISTORSv 4HE THIRD APPROACH TO EMPLOYING SOLID 
 or receiver. A portion of the transmitted signal is intercepted by a reflecting object  (target) and is reradiated in all directions. 1.t is the energy reradiated in the back direction that  is of prime interest to the radar. 
 pp .. l4 4\ March. 1960. 
 The name ambiguity function for I X(T,, fd) I2 is somewhat misleading since this function  describes more about the waveform than just its ambiguity properties. Woodwards coined the  name to demonstrate that the total volume under this function is a constant equal to (2~)',  independent of the shape of the transmitted waveform, [Eq. (1 1.54)]. 
 DOPPLER REF 
 Average power input (Walls)  Frequency (Gkiz) aJ 0  t" (b) 9  Peak current (A)  Figure 6.6 Performance characteristics of the coaxial magnetron. (a) Variation of power output,  efficiency, and peak voltage of the SFD-341 as a function of the input average power for a fixed frequency  (5.65 GHz); pulse width = 2.15 p, duty cycle = 0.0009. (6) Variation of peak power output and peak  voltage of the SFD-341 with frequency for a fixed current (23.9 A); pulse width = 1.8 p, and duty  cycle = 0.0009. 
 ' R F  input -:.. .: output  Figure 6.1 1 Diagrammatic representation of the traveling-wave tube.  206INTRODUCTION TORADAR SYSTEMS 6.4TRAVELING-WA VE-TUBE AMPLIFIER Thetraveling wavetube(TWT)isanotherexample ofalinear-beam, orO-type,tllhe.Itdifkrs fromtheklystron amplifier bythecontinuous interaction oftheelectron beamandtheRF fieldovertheentirelengthofthepropagating structure ofthetraveling-wave tuhcratherthan theinteraction occurring atthegapsofarelatively fewresonant cavities. 
   2!$!2 #2/33 3%#4)/.   £{°{£ RADARS WHEN THE & 
 (AJter  (dl White. ' ')  (blMTIANUPULSE UOPI'LER RADAR113 uscdtilefiltcriscallcdrecursive. Usingthc Z-lransformas thebasisfordesignitispossible in principle tosynthesize almostanyfrequency-response function.2.11-13 Thecanonical configuration isuscfulforconceptual purposes, butitmaynotalwaysbe desirable todesignafilterinthismanner. 
 the computed vertical-plane radar coverage patterns for (a) horizontal polari-  ratio11 and (17) vertical pola1i7atiori.  Radio and radar waves travel in straight lines in free space. However, electromagnetic waves  propagating within the earth's atmosphere do not travel in straight lines but are generally bent  or refracted. 
 2rcosex2(1)r"cosex2(1)rX!d=-.-------- ..=------ =.A A )(14.20) wherer=velocity ofpointP.Fromthisequation, theresolution inthexdimension canbe written .)1) )dx=d!d-.=-----'---=----.2(1)rT2(dOjT) 2dO(14.21) whereTisthecoherent integration timeequaltoI/(d/~),anddOistheanglethrough whichthe bodyrotatesduringthetimeT.Itdoesnottakemuchofanangularrotation toproduce good resolution atmicrowave frequencies. Thecontours ofconstant doppler areperpendicular to thexaxis,andcontours ofconstant rangelieparalleltothexaxis. Iftheangleoftargetrotation overwhichthedoppler isobserved istooshort,thedoppler spectrum isbroadandtheresolution islow.Increasing theobservation timenarrows the spectrum andtheresolution wil1increase. 
 Nevertheless, it is clear that  uncritical use of published clutter data could lead radar systems designers to choose  sea clutter estimates many dB apart for the same conditions. The NRL 4FR data set is unique in that no other program has reported measure - ments made over so wide a range of frequencies, grazing angles, and wind speeds at the  same time. Figure 15.4 shows the trends  for both vertically and horizontally polarized  FIGURE 15.3  Comparison of X-band clutter data from different sources for a nominal wind speed of  15 kn: ( a) vertical polarization and ( b) horizontal polarization ( based on data from H. 
 TIONS  AND THEREFORE REQUISITE SOLUTIONS  OF ADAPTING -4) SYSTEMS TO THE ENVIRONMENT 4HESE FOUR ADVANCES HAVE MADE IT PRACTICAL TO USE SOPHISTICATED TECHNIQUES THAT WERE CONSIDERED  AND SOMETIMES TRIED  MANY YEARS AGO BUT WERE IMPRACTICAL TO IMPLEMENT %XAMPLES OF EARLY CONCEPTS THAT WERE WELL AHEAD OF THE AVAILABLE TECHNOLOGY WERE THE VELOCITY INDICAT 
 Angle-gate stealing is particularly effective against conical-scanning or sequen - tial-lobing tracking radars. It is for this reason that such trackers cannot be used  in military applications. The fundamental problem with these radars is that angle  tracking is accomplished by demodulating the amplitude modulation imposed on  the target return pulses over a complete scanning or lobing cycle. 
 Catnhridge Researclr Center Geopkps.  Rcsrarrlr Papers, no. 52, July; 1956. 
 SPECULAR AND PLATEAU REGIONS THE PLATEAU EXTENDS TO VERTICAL   AND TOO LITTLE IS KNOWN TO ESTABLISH WHETHER A SHADOW REGION EXISTS &OR NEARLY EVERY TYPE OF TERRAIN  THE MEASURED DATA FITS CLOSELY TO THE FORM   SQQ 
 43. P. O. 
 ‘“’x”~/-, /\——— Current tounmodified machine 10–/ ‘\— Represents machines with aux!llary stat’hng I\relay 8-I \ \ ! I\ \ 6 i\ :~ o-.— 0 0.2 0.4 0.6 0.8 1.0 1 Time inseconds214.4 and FIG. 14.6.—Starting current of1500-va motor- alternator, Signal Corps Type PE-218-D. Noload cmalternator.. 
 WAY LOSS 0ROPAGATION LOSS IS MORE OF A ENVIRONMENTAL LOSS THAN A SYSTEM LOSS  BUT CAN BE GROUPED WITH THE OTHER LOSSES THAT MAKE UP NET LOSS IN THE RADAR RANGE EQUATION 3CAN ,OSS "ROADSIDE ELECTRONICALLY SCANNED ARRAY ANTENNAS ARE SUBJECT TO  REDUC 
 Strapdown inertial measurement units for motion compensation for synthetic aperture radars. IEEE T rans. Aerosp. 
 The left panel shows on-pulse (red) and o ﬀ-pulse (blue) power as a function of frequency, integrated in time across the pulse. 104. Sensors 2019 ,19, 3344 The high spikes in the on-pulse power correspond to strong, narrowband spikes within each microburst. 
 , $ESNOS ET AL  h4HE %.6)3!4 ADVANCED SYNTHETIC APERTURE RADAR SYSTEM v  0ROC  )'!233  VOL   PP n    0 &OX  ! 0 ,USCOMBE  AND ! ! 4HOMPSON  h2!$!23!4 
 Pressurization of the rotary joints, when necessary, isaccomplished, either bymeans ofa composition rubber ring. revolving snugly around apolished steel tube, or bymeans ofapolished carbon ring revolving incontact with apolished steel annulus. Helical scanners have atleast two rotary joints, i.e.. 
 2011 ,116, A04303. [ CrossRef ] 12. Wang, C.; Zhang, M.; Xu, Z.-W.; Zhao, H.-S. 
 242-246. May. 1960. 
 72. Clieston. T. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo.  GROUND ECHO  16.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 In practice, antenna beams are not rectangular. 
 Ostroff, E., M. Borkowski, H. Thomas, and J. 
 $  WEATHER RADAR IMAGES ON THE ./!! )NTERNET SITES.   -4) 2!$!2  Ó°Ç &)'52%  34# CAN GREATLY REDUCE THE NUMBER OF BIRDS DISPLAYED 2ANGE  NMI  A  "IRDS SEEN WITH  -4) AND B  BIRDS SEEN WITH -4) AND 34# &)'52%    )NSECTS WITH AND WITHOUT 34# AND RANGE  MILES  A  BATS AND INSECTS SEEN WITH -4) AND  B  BATS AND INSECTS SEEN WITH -4) AND 34# . 
 47, pp. 855–863, May 1959. 34. 
 REVERSED VERSION OF THE AUTOCORRELATION FUNCTION #ONDITIONS FOR 4ARGET 2ESOLUTION IN 4IME $ELAY AND $OPPLER &REQUENCY    !SSUME THAT TWO TARGETS WITH EQUAL RADAR CROSS SECTIONS ARE PRESENT AT THE SAME ANGULAR  POSITION 4HE FIRST TARGET TERMED THE  REFERENCE TARGET  IS LOCATED AT THE ORIGIN OF THE  DELAY 
 InFig. 3.24, for. SEC. 
 A fixed phased array requires electronic beam steering that  complicates the radar. If the flexibility of an electronically steered array is not needed. tllc  advantages of an array antenna for combining the radiated power from many individual  sources can be had by mechanically scanning the entire antenna. 
 CIPLES 4HE MAGNETRON IS CONNECTED TO THE ANTENNA VIA A DUPLEXER AND A ROTATING JOINT 4HE MAGNETRON HAS A TYPICAL OPERATIONAL LIFE OF ABOUT   HOURS AND IS BY FAR THE LOWEST LIFED COMPONENT IN THE WHOLE SYSTEM 4HE DUPLEXER IS NOWADAYS A THREE 
 51. 7'ollefson. R. 
 Hoekman, “Radar backscattering of forest stands,” Int. J. Remote Sensing , vol. 
 2, pt. I, pp. 272-293, 1958. 
 TION 4HE TERM TIME 
 NIFICANTLY REDUCED MANNING NO OPERATORS  4HE RADAR PERFORMS SUCH FUNCTIONS AS HORIZON SEARCH  LIMITED ABOVE 
 299-307, 1970.  76. Puhakka, T.: On the Dependence ofthe Z-R-Relation on the Temperature in Snowfall, Prepritirs 16111  Rudur Meteorology Conference, Am. 
 A greatly simplified phased array system becomes possible  if there is no need for multifunction capabilities, including fire control, where a beam  may have to be pointed in any given direction at any time. The array is scanned in the  vertical plane only and mechanically rotated to give azimuth coverage. The number  of phase control points is then reduced to the number of horizontal rows. 
 (3.39) gives the maximum unambiguous range of a pulse radar.  A qualitative explanation of the operation of the two-frequency radar may be had by  considering both carrier frequencies to 'be in phase at zero range. As they progress outward  from the radar, the reJative phase between the two increases because of their difference in  frequency. 
 In this application contest, the SAR datasets available for training the network are often limited, whereas CNNs require thousands of examples to avoid overﬁtting. In order to overcome this problem, the proposed algorithm starts with an augmentation method for enlarging the training dataset. Then, transfer learning is used for improving the classiﬁcation accuracy. 
 Accordingly, the number of pulses at one azimuth angle can be equivalently increased by merging the forward prediction pulses and the backward prediction pulses with the original pulses. Finally, the “merged pulses” are utilized to perform the DBS imaging. The number of “merged pulses” in the proposed KA-DBS algorithm is twice larger than that in the conventional DBS algorithm with the same dwell time. 
 TIME 
 M. Lhermitte, “Dual-doppler radar observations of convective storm circulations,” in 14th  Conf. Radar Meteorol. 
 itisdecreased. If.forexample, thetargetisapproaching theradar,thebeatfrequency fb(UP)produced duringtheincreasing, orup,portionoftheFMcyclewillbethedifference between thebeatfrequency duetotherangef,andthedoppler frequency shiftfd[Eq.(3.l2a)]. Similarly, onthedecreasing portion, thebeatfrequency Ji,{down) isthesumofthetwo [Eq.(3.12b)]' fb(UP)=f,-fd fb(down)=f,+fd(3.12a) (3.12b) Therangefrequencyf,maybeextracted bymeasuring theaveragebeatfrequency; thatis, ![fb(UP)+fb(down)]=fr.Iffb(up) andfb(down) aremeasured separately, forexample, by switching afrequency countereveryhalfmodulation cycle,one-half thedifference between the frequencies willyieldthedoppler frequency. 
 Uijlenhoet, M. Steiner, and J.A. Smith, “Variability of raindrop size distributions in a squall  line and implications for radar rainfall estimation,” J. 
 On the other hand, a  large number of bits is required for best performance in terms of gain, sidelobes, and  beam-pointing accuracy. Phase Errors . The phase of a phase shifter having P bits can be set to the desired  value with a residual error:  Peakphaseerror= = ±απ 2P (13.23)  RMSphaseerror= =σπ φ2 3P (13.24) Loss in Gain . 
 X4.Bhagavan. B.K,andR.J.Polge:Performance oftheg-hFilterforTracking Maneuvering Targets. [EEETrl/lls..vol.AFS-IO. 
 ERN COMPACT OFF 
 However, theamplitudes ofthemoving-target echoesarcnotconstant frompulse10pulse,and subtraction resultsinanuncanceled residue.Theoutputofthesubtraction circuitisbipolar Unipolarvideo Toindicator Figure4.4MTIreceiverwithdelay-line canceler.. MTI AND PULSE DOPPLER RADAR 105  video, just as was tlie input. Uefore bipolar video can intensity-modulate a PPI display, it nlusl  bc cnnvcrtctf to u~iil,otential voltages (unipolar video) by a full-wave rectifier. 
 MUTH SIDELOBES ! CONVENTIONAL BEAMFORMING APPROACH WOULD INCORPORATE AN ARRAY AT THE FOCAL PLANE WITH A SINGLE BEAM PER FEED HOWEVER  THE ASSOCIATED PHASE DISTORTION DUE TO DISPLACEMENT CAUSES POOR  AZIMUTH  SIDELOBES 4O  CORRECT THIS PROBLEM  THE FEED ARRAY IS PLACED FORWARD OF THE AZIMUTH FOCAL POINT  ENABLING COMPENSATION AND SIDELOBE IMPROVEMENTS VIA USE OF MULTIPLE FEEDS PER BEAM WITH APPROPRIATE FEED PHASING &IGURE A  4WO DIFFERENT FOCAL LENGTHS ARE USED IN THE REFLECTOR  ONE FOR ELEVATION AND A LONGER ONE FOR AZIMUTH 4HE FEED IS ON A CURVED SURFACE  OPTI 
 395–412, 1987. 46. R. 
 STATION AMPLIFIERS )N PARTICULAR  THE 'A. (&%4 DEVICE DEMONSTRATES PHYSICAL PROPERTIES THAT MAKE IT USEFUL AS A HIGH GAIN DEVICE WITH VERY HIGH POWER OUTPUT CAPABILITY INTO THE 7 BAND 4HE 3I# -%3&%4 WILL LIKELY BE COMPETITIVE AT THE LOWER FREQUENCY RANGES OF , BAND THROUGH # BAND  4HE THERMAL CONDUCTIVITY OF THE 3I# SUBSTRATE IS SUPERIOR TO 'A!S BY NEARLY AN  ORDER OF MAGNITUDE  AND THE NORMALIZED POWER OUTPUTS ARE MUCH  MUCH HIGHER IN THE  WIDE BANDGAP SEMICONDUCTORS THAN CURRENTLY BEING ACHIEVED USING 'A!S AT ANY VOLT 
 BANDWIDTH PRODUCTS  OR EQUIVALENTLY  ITS POTEN 
 Transmitter Duplexer LimiterHPA Radar Type Phased Array Radar Type Beam-forming Network T/R T/R T/R T/R    Figure 13.26  Conventional and phased -array Radar in comparison.    . Radar System Engineering  Chapter 12 – Selected Radar Applications  159     The typical requirements on a T/R module can be summarized as follows:      2001  ab 2002   Output power:  4 – 10 W > 16 W   Noise figure:  ≤ 4 dB  < 2.5 dB   Region of adjustable phase  360 °    Phase resolution  6 bit   Region of adjustable amplitude  ≥ 30 dB    Amplitude resolution  6 bit   Efficiency  > 18 %  > 35 %   Bandwidth  > 20 %    Weight per module  ≤ 120 g    Dimensions per module  ≤ 50 cm3   T/R modules can be realized by different methods. 
 S!$tent considerations. Orie of the attractive features claimed for a multiple-beam-forming  arrav is that it does away with phase shifters. These are replaced, however, by multiple  receivers, one for each beam. 
 6.14), using anantenna of 20-in. diameter. Itwas found that therange “performance was marginal. 
 28. M. I. 
 MODULE VARIATIONS  ALLOWING LESS DEMANDING SPECIFICATIONS 4HE TRIMMER WOULD ALSO PROVIDE A DEGREE OF FREEDOM IN APERTURE CONTROL FOR SPECIAL SITUATIONS "ECAUSE THE NOISE FIGURE HAS BEEN ESTABLISHED  THE FEED NETWORK MAY BE SPLIT TO GIVE SEPARATE OPTIMUM APERTURE AMPLITUDE DISTRIBUTIONS FOR TRANSMITTING AS  WELL AS FOR RECEIVING ON SUM AND DIFFERENCE CHANNELS )N AN ALTERNATIVE CONFIGURATION   THE FEED NETWORK COULD BE DESIGNED FOR A CONSTANT AMPLITUDE APERTURE DISTRIBUTION TO GIVE HIGHEST TRANSMIT POWER ON THE TARGET  AND THE RECEIVER GAI N CONTROL COULD BE USED  TO PROVIDE AN AMPLITUDE TAPER FOR THE SUM CHANNEL 0ERHAPS A SECONDARY FEED SYSTEM COULD BE ADDED FOR THE DIFFERENCE CHANNELS 0OIRIER  HAS ANALYZED THIS CASE  THE EFFECT  ON NOISE  AND THE DEGRADATION DUE TO AMPLITUDE QUANTIZATION STEPS 4HE MODULE PHASE SHIFTER OPERATES AT LOW 
 VENT THERMIONIC EMISSION 4HE CONTROL ELECTRODE NEEDS ONLY A SHORT  MEDIUM 
 665-668. 127. Schoenenberger, J. 
 To avoid false alarms, the threshold detector at the  output of such a receiver must be set to a higher value than when the clutter is Rayleigh.  The increased threshold needed to avoid false alarms is significant ( 10 to 20 dB, or more, in  some cases).  The log-normal probability density function has been proposed to model the clutter  echo with very high-resolution radar and at the higher sea states. 
  AND & 
 ING CORNER REFLECTORS WITH STRONG ECHOES 4HEY ALSO CAN HAVE MANY INDIVIDUAL SCAT 
 at 10 GHz,29 both for upwind directions. Thus they can be viewed as representative of clutter behavior in the vicinity of X band, since the difference between the two frequencies is small. However, examination of the data points underlying these linear regres- sions show point scatter that sometimes resembles Fig. 
 Septemher. 1976. 53.Lamb.J.J.:AnoiseSilencing I.F.CircuitforSuperheterodyne Receivers. 
 Rangeambiguities areavoided withalowsampling rate(lowpulse repetition frequency), anddoppler frequency ambiguities areavoided withahighsampling rate.However, inmostradarapplications thesampling rate,orpulserepetition frequency, cannotbeselected toavoidbothtypesofmeasurement ambiguities. Therefore acompromise mustbemadeandthenatureofthecompromise generally determines whether theradaris calledanMTIorapulsedoppler. MTIusuallyreferstoaradarinwhichthepulserepetition frequency ischosen lowenough toavoidambiguities inrange(nomultiple-time-around echoes). 
 3.1.1–3.1.4.  94. S. 
 Ri~ze. J.: Physical Liriiitatioris on Antennas. MI T Researcl~ Lnh. 
 The method isnot applicable toarotating-coil system because ofitsinertia. Fortunately, however, this type ofdisplay isitself exceedingly accurate inangle, so that themechanical cursor can beused onthecentered PPI display with little error except that due toparallax. 13.12. 
 AP-24, September, 1976.  152. Sharp, E. 
  =         .EFF   ;3.2D"   
 That is, a tangent plane is passed through the surface coordinate at the patch dS, and the total surface fields are taken to be precisely those that would have existed had the surface at dS been infinite and perfectly flat. Thus the unknown fields in the integrals of Eqs. (11.9) and (11.10) may be expressed entirely in terms of the known incident field values. 
 WAY HALF 
 For our algorithm, the estimate of this parameter can be computed as the equivalent bandwidth of the reference in range function. Also, in this case a close adherence of the theoretical and experimental relative bandwidth has been obtained, as reported in the Table 3. T able 3. 
 maybeplacedofT-axis 10avoidreflections fromthebackfaceofthelens,ifdesired.Itis possible inalensarray10reducethenumberofphaseshiftersby"thinning" thenumberof outputradiators. Thisisaccomplished bycombining pairsofinputelements andfeedingthe outputofeachpairtoasingle-phase shifterandradiating element. Thethinnedelements are neartheouterportionoftheantennaratherthanatthecentersoastoproduceadensitytaper (Sec.R.10).Thisprocedure, whilereducing thenumberofphaseshifters,generally resultsin lowergainandhigherfar-outsidelobes thanwouldbeproduced byanamplitude taper. 
 Crawford, and W. W. Mumford: Some results of a Study of Ultra-short-wave  Transmission Phenomena, Proc. 
 Extra cycles will also appear inthevideo pulses ifthemagnetron fre- quency varies during the transmitted pulse. Such variation occurs chiefly atthe beginning and end ofthe pulse. IfAflisthe maximum departure infrequency from the value inthe central part ofthe pulse, thenumber ofbeat cycles iscertainly less than TAfl. 
 I. Skolnik (ed.),  McGraw-Hill Rook Co .. New York, 1970. 
 1.7 3 ~0.5 0.63  Forest X I .4 0.17 0.7 0.51 0.53  Cultivated land X I .4 0.1 7 0.7-5.0 0 61 2 ()  Sea state I X 0.5 002 4. 7 145  Sea state 3 K" 5 01 J.O 30.0 I 16 1.78 . RADAR CLUTTER 497  well as the fact that radar waves can penetrate the surface and can be scattered from discon­ tinuities underneath the surface. 
 As discussed in Section 13.5, the loss in gain is σφ2, which with  Eq. 13.24 gives  ∆GP≈ =σπ φ22 21 32 (13.25) With many array elements, this result is statistically independent of the amplitude  distribution. An enumeration of Eq. 
 PULSE  !-4) ARE SHOWN IN THE PHASOR  DIAGRAM IN &IGURE  4HE PHASE ADVANCE BETWEEN THE FIRST PAIR OF PULSES FIRST AND SECOND PULSE FOR THE THREE 
 91.Konrad. T.(i.J..IlIicks.andF.B.Dohson: RadarCharacteristics ofBirdsinFlight.Sciellcc. vol. 
   PP n  *ULY   , 3OLOMON  h2ADAR CROSS SECTION MEASUREMENTS (OW ACCURATE ARE THEY v  %LECTRONICS  VOL    PP n  *ULY     7 ( %MERSON AND ( " 3EFTON  *R  h!N IMPROVED DESIGN FOR INDOOR RANGES v  0ROC )%%%  VOL    PP n  !UGUST   ( % +ING  & ) 3HIMABUKURO  AND * , 7ONG  h#HARACTERIS TICS OF A TAPERED ANECHOIC CHAMBER v  )%%% 4RANS  VOL !0 
 The losses in decibels per 100 ft for radar  transmission lines are shown in Fig. 2.28. At the lower radar frequencies the transmission line  introduces little loss, unless its length is exceptionally long. 
 GRAZING INCIDENCE v  )%%%  4RANS ON !EROSP %LEC 3YS  VOL   PP n    * " "ILLINGSLEY ET AL  h3TATISTICAL ANALYSES OF MEASURED RADAR GROUND CLUTTER DATA v  )%%% 4RANS  !EROSP  %LECTRON 3YS VOL   PP n    2EF   VOL ))  PP n  & 4 5LABY  7 ( 3TILES  $ "RUNFELDT  AND % 7ILSON  h 
 MTI AND PULSE DOPPLER RADAR 121  that the signals are of the same amplitude and with a spacing such that when pulse a1 is  subtracted from pulse a2, the result is zero. However, a residue is produced when pulse a3 is  subtracted from pulse a4, but not when a5 is subtracted from a4, and so on. In the quadrature  channel, the doppler-frequcncy signal is shifted 90° so that those pulse pairs that were lost in  the I channel are recovered in the Q drnnnel, and vice versa. 
 114-120. January, 1958.  114. 
 A filter can be used to exclude the  clutter but pass the target echo. Similarly, if the targets are receding from one another along  headings 180" apart, the target doppler frequency shift will again lie outside the clutter spec-  trum and may be readily separated from the clutter energy by filters. In other situations where  t tie radar may be closing on the target from the tail or from the side, the relative velocities may  be small and the target doppler will#lie within the clutter doppler spectrum. 
 -d/2 A(7.23) Suhstituting Eq.(7.14)intotheahoveandchanging thevariable ofintegration froml'to~to avoidconfusion. theantenna patternbecomes 1 .di2.r£'IzIE,,(¢)=1.1.rE(()expj2rr:;(sinl'-sin()d(sin0dz 1\a,l," Il Interchanging theorderofintegration. theapproximate antenna patternis EA1')=c!("E(C)sin[rr(d/A)~sin ¢-.sinOJd(sin ~) A. 
 N0. is the noise power per unit bandwidth, and k is a  constant whose value is of the order or unity. For a time-delay measurement, k depends on the  shape of the frequency spectrum S(f ), and M is the rise time of the pulse; for a doppler  fre4uency measurement, k depends on the shape of the time waveform s(t) and M is the  spectral resolution, or the reciprocal of the observation time; and for an angle measurement k  depends on the shape or the aperture illumination A(x), and M is the beamwidth. 
   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°Î PROCESSING  CONVENTIONAL MONOPULSE ANGLE TRACKING  JAMMER NULLING  AND OUT 
 APERTURE  % 
 The process of  controlling each and every sidelobe is thus seen as formidable, since the total num - ber of sidelobes is approximately equal to the number of elements in a phased array.   For a 5000-element array and a probability of 0.999 that a single sidelobe will not  exceed RT at any single location, it will still be expected that 5 sidelobes will exceed  RT when all 5000 sidelobe locations are taken into account. For very low sidelobe arrays, it is reasonable to allow a few sidelobes to exceed  the MSSL value by as much as 10 to 12 dB to account for random variations. 
 GE-18,  pp. 353–361, 1980. 141. 
 L.. ant1 R. C. 
 2014 ,7, 2797–2810. [CrossRef ] 2. Crisp, D.J. 
 OVERLAPPING IN TIME TO AVOID A  D" INCREASE IN PEAK POWER AND BECAUSE MOST RADAR TRANSMITTERS ARE OPERATED IN SATURATION AND SIMULTANEOUS TRANSMISSION AT MULTIPLE FREQUENCIES WOULD PRODUCE SIGNIFICANT TRANSMITTED INTERMODULATION DISTORTION 4HE SENSITIVITY BENEFIT OF DIPLEX OPERATION FOR DETECTING 3WERLING  TARGETS IS SHOWN  IN &IGURE   INCREASING WITH PROBABILITY OF DETECTION  0 $  &OR EXAMPLE  DIPLEX OPER 
 For example, wind speed certainly seems to affect clutter levels, but the cor - relation of clutter with, say, a ship’s anemometer readings is often inconsistent. And  although the state of agitation of the sea surface ( sea state ) appears to have a strong  effect, it is a subjective measure and its relation to prevailing local winds is often  uncertain. Moreover, it has been found that the temperatures of the air and the sea  surface can affect the way in which measured wind speed is related to the generation  of clutter-producing waves, yet the importance of these effects were unappreciated  over most of the history of sea clutter measurements, so air and sea temperatures were  seldom recorded. 
 The required difference-pattern  slope is determined by the derivative of the scan pattern, which differs from the DPCA  criterion. This technique is known as step-scan compensation  because the system elec - tronically points the antenna slightly ahead of and behind of boresight each pulse so  that a leading and lagging pair are taken from successive returns to obtain the effect of  the antenna remaining stationary. Figure 3.15 shows the improvement obtained by Dickey and Santa7 for single- delay cancellation. 
 The power received from a given target  is directly related to the square of the antenna gain, while the antenna is used both for transmitting  and receiving.    The antenna gain increases  the transmitted  power in one desired direction.    The reference is an isotropic antenna,  which equally transmits in any arbitrary  direction. 
 Malech: Mutual Coupling in Infinite Scanning Arrays," Microwave Scanning  Antennas, vol. II," R. C. 
 Liebman: A Report on the Sperry Dome Radar, Microwm•e J., vol. 22.  pp. 
 Tis estimated via T=supp (s0:|s0|>α), (11) which is the support of the elements whose amplitudes are larger than α. In [17], the threshold αis determined by the b%-Energy support, which means that Tcontains at least b% of the signal energy. In WASAR imaging, we set b%=90%. 
 The noise plus dis - tortion includes all spectral components, excluding DC and the fundamental up to  the Nyquist frequency. SINAD is a useful figure of merit for A/D converters, but in  digital receiver applications, where the worst spurious components may fall outside of  the bandwidth of interest, it is not necessarily a key discriminator between competing  converters for a specific application. Effective Number of Bits (ENOB). 
 BAND RADAR CROSS 
 Baier, M. M. Quintino da  Silve, and W. 
 [ CrossRef ] 34. Wu, W.; Hu, P .; Xu, S.; Chen, Z. Image registration for InSAR based on joint translational motion compensation. 
 METRICAL CODES  THE CODE AND ITS INVERSE ARE IDENTICAL -AXIMAL 
 Onthe other hand, electrons which leave the cathode atsuch atime and place that they transfer energy to the r-ffield continue around the cathode inacycloidal path which expands toward the anode, transferring tothe r-ffield the energy they gain from the d-cfield.. SEC.103] ELECTRON ORBITS AND THE SPACE CHARGE 335 Itmust again beemphasized that theabove description iscorrect in terms ofgeneral principles, but the detailed picture isdoubtless more complicated. One experimental fact difficult toexplain isthe extra- ordinarily high electronic efficiencies ofsome magnetrons: upto85 percent. 
 2, pp. 186-199, 1957.  3. 
 J. Fredricks: Range-Doppler Imagining with Motion Through Resolution  Cells. IEEE Trans.. 
 S AS  PART OF THE -OLECULAR %LECTRONICS FOR 2ADAR !PPLICATIONS -%2!  PROGRAM INITI 
 and G. D. Thayer: "A World Atlas of Atmospheric Radio  Rdractivity." U.S. 
 14,  pp. 978–987, 1997. 18. 
 White, “Diode phase shifters for array antennas,” IEEE Trans ., vol. MTT-22, pp. 658–674,  June 1974. 
 WAVE DELAY LINE . n°£Ó  2!$!2 (!.$"//+  .ONLINEAR  &REQUENCY  -ODULATION  7AVEFORMS  4HE NONLINEAR 
 2005 ,67, 1054–1062. [CrossRef ] 9. Huang, X.; Reinisch, B.W. 
 (a) Entropies change of the two sub-images during iteration; ( b) IC values change of the two sub-images during iteration. The geometrical features of the ships are extracted for further assessment. The features include the length, width and area. 
 FRAME  KM SQUARE    ON A MAINFRAME COMPUTER.   30!#% 
 The videobandwidth b,asdistinguished from thei-fbandwidth ~,has hitherto been assumed tobesogreat astoallow reproduction ofthe detected i-fsignal without distortion. This isseldom true inpractice and the question arises, how does the video bandwidth influence the signal discernibility y,and how narrow can itbewithout harm? Making thevideo bandwidth bconsiderably less than I/ramounts toputting the rectified signals and noise through along-time-constant filter. This isa sort ofaveTaging, orintegration process, ineffect, thefinal output atany instant being anaverage over several adjacent intervals, each oftheorder ofrinduration. 
  MISSION TO THE -OON v 0APER    0ROCEEDINGS  ,UNAR AND 0LANETARY  3CIENCE 8886)  (OUSTON  48  VOL    2 + 2ANEY  h(YBRID 
 QUANTIZATION LOBES SEEM TO OCCUR WITH A PHASE SLOPE SUCH  THAT THE ELEMENTS ARE SPACED BY A DISTANCE EXACTLY ONE 
 aa PPSIN    FOR     WHERE 4  IS THE PULSEWIDTH   " IS THE SWEPT BANDWIDTH  AND  K IS A TIME SIDELOBE LEVEL  CONTROL FACTOR 4YPICAL K VALUES ARE  AND   WHICH YIELD TIME SIDELOBE LEVELS OF n D" AND   n D"  RESPECTIVELY &IGURE  IS A PLOT OF PEAK TIME SIDELOBE LEVEL AS A FUNCTION OF THE  TIME SIDELOBE CONTROL FACTOR K   FOR VARIOUS 4" PRODUCTS  FOR THIS .,&- WAVEFORM &)'52%     !MBIGUITY FUNCTION OF AN ,&- WAVEFORM COMPARED TO A SYMMETRICAL .,&- WAVEFORM   
 If,forexample, the bandwidth oftheIFamplifier wereIMHzandtheaverage false-alarm timethatcouldbe tolerated were15min,theprobability ofafalsealarmis1.11x10-9•FromEq.(2.24)the threshold voltagenecessary toachievethisfalse-alarm timeis6.45timesthermsvalueofthe noisevoltage. Thefalse-alarm probabilities ofpractical radarsarequitesmall.Thereasonforthisisthat thefalse-alarm probability istheprobability thatanoisepulsewillcrossthethreshold during anintervaloftimeapproximately equaltothereciprocal ofthebandwidth. ForaI-MHz bandwidth, thereareoftheorderoflQ6noisepulsespersecond. 
 According toEq. (22) weexpect tofind among these some hundred that represent noise peaks greater than 10Po. Inonehour there isbetter than aneven chance ofobserving one noise peak greater than 20P0. 
 PUTS AT THE CLOCK RATE  &)'52%   %IGHT 
 J. C. Scott, “Surface films in oceanography,” in ONRL Workshop Proc.—Role of Surfactant Films  on the Interfacial Properties of the Sea Surface , F. 
 PORARY TRACKING OF TRUE AND FALSE TARGETS IN BOTH RANGE AND DOPPLER DIMENSIONS 4HE USE OF MULTIMODE HIGH  LOW  AND MEDIUM 02&  RADARS CAN ALSO BE AN EFFECTIVE %##- MEASURE HELPING TO COUNTER RANGE 
 Phasedarray antennas andlensantennas offerthepossibility ofscanning thebeamwithout thenecessity for movinglargemechanical masses.Thepresentsectionconsiders thepossibility ofscanning the beamoveralimitedanglewithafixedreflector andamovable feed.Itismucheasierto mechanically position thefeedthanitistoposition theentireantenna structure. Inaddition, largefixedreflectors areusuallycheaper andeasiertomanufacture thanantennas whichmust bemovedabout. Thebeamproduced byasimpleparaboloid reflector canbescanned overalimitedangle bypositioning thefeed.1,26-29However, thebeamcannotbescanned toofarwithoutencoun­ teringseriousdeterioration oftheantenna radiation patternbecauseofincreasing comaand astigmatism. 
 28, pp. 89-106, August. 1964. 
 Many people will have seen a cathode-ray tube in use  in a television set: the greyish-green glow is familiar  both in laboratory test gear and in entertainment tele-  vision. But in television we see, normally, the complete  picture formed on the end of the tube. We do not see  the tiny pencil of invisible electrons which leave the  cathode at the ‘small’ end of the tube and trace a pattern  on the fluorescent screen at the larger end. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 high range resolution or reducing the peak power. 
 Most reflectors are chosen to have a focal length between 0.25 and 0.5 times the diameter.PARABOLICREFLECTION VERTEXPLANE WAVEFRONT BEAM AXISFOCUS . f/D FIG. 6.5 Subtended angle of the edge of a paraboloidal reflector. 
 LEVEL $"& REQUIRES A DIGITAL RECEIVER  WHICH CONSISTS OF A DOWNCONVERTER AND AN !$#  AT EACH ELEMENT 3UBARRAY 
 ALTITUDE TARGETS CAUSE SEVERE ELEVATION 
 ENCES !LERT .OT ALL ONLINE RESOURCES ARE ACCURATE THE READER IS ADVISED TO SEEK OUT MORE THAN ONE AND TO VERIFY INFORMATION BY CROSS 
 9.Shreve,J.S.:DigitalSignalProcessing, chap.35of"RadarHandbook," M.l.Skolnik(cd.),McGraw­ HillBookCo.,NewYork,1970. 10.Hill,J.J.:DesignofNonrecursive DigitalMoving-Target-lndicator RadarFilters,Electrollics teller, vol.8,pp.359-360, July13,1972. 11.Rabiner,L.R.,andC.M.Radar:..DigitalSignalProcessing," IEEEPress,NewYork,1972. 
 Gma,=maximum value ofeffective gain. (PS,)~., =maximum value ofthe available peak po~ver received by thebeacon. P,,=peak value ofthe power transmitted bythe interrogator (radar). 
 17 .24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 the corresponding main-beam clutter-only cells. It accomplishes this by transmitting  a coherent burst of pulses that are subsequently received by each of three linearly dis - placed subarrays (or interferometer ports). In each channel, the pulses are fast-time  and slow-time processed into a set of range and doppler cells whose intensities may  be considered as a SAR image of the scene (although not as fine in range or doppler  resolution as in the SAR mode and generally not with a nominally square PSF). 
 Clifford Bell, “Radar countermeasures and counter-countermeasures,” Mil. Technol .,   pp. 96–111, May 1986. 
 F. T.. and P. 
 SEC.11.11]DESIGN CONSZDERA TZONS FORTHER-FHEAD 421 forconfining the disturbances setupbythe radar transmitter sothat they donot affect other equipment. 11.11. Design Considerations forthe R-f Head.—The form which ther-fhead takes will depend onwhether itoperates ontheground, ona ship, orinanairplane; onthedegree ofexposure totheelements; and on thepower and transmitting frequency ofthemagnetron. 
 The video output jack required can bethenormal output totheindicator, inwhich case aninterchange ofcable isrequired. Ifthe video output tube is capable ofhandling parallel loads, asecond jack fortest purposes on]y would beadded. Ifthe test setrequires atrigger signal atthe time of themagnetron pulse, this can beobtained byinserting afew ohms inthe bypass-to-ground circuit atthe low end ofthe pulse transformer. 
 VIDED AT THE MOST SIGNIFICANT END OF THE ADDERS IN ORDER TO ACCOMMODATE THIS INCREASED SIGNAL LEVEL &IGURE  IS A FLOW CHART THAT  REPRESENTS THE #/2$)# ALGORITHM TO IMPLEMENT A PHASE SHIFT 4HE INPUTS TO THE ALGORITHM ARE THE ) IN  1IN  AND EIN  THE DESIRED PHASE SHIFT  4HE VARIABLE  I  WILL KEEP TRACK OF THE PROCESSING STAGE BEING PERFORMED AND IS INITIALIZED TO ZERO 4HE BASIC ALGORITHM CAN PERFORM A PHASE SHIFT BETWEEN  o O )F THE DESIRED  PHASE SHIFT IS OUTSIDE OF THAT RANGE  THE INPUT ) AND 1 VALUES ARE FIRST NEGATED  IMPOSING A  O PHASE SHIFT  AND O IS  SUBTRACTED FROM THE DESIRED PHASE SHIFT 4HE NEW PHASE SHIFT IS NOW WITHIN  o O   AND THE ALGORITHM PROCEEDS NORMALLY .EXT  THE ALGORITHM LOOPS THROUGH  . ITERATIONS WITH THE GOAL OF DRIVING THE RESIDUAL PHASE ERROR   E  TO ZERO )N  EACH ITERATION  A NEW  E IS CALCULATED BY  SUBTRACTING OR ADDING THE PHASE SHIFT FOR 4!",%  #/2$)# 0ARAMETERS FOR &IRST %IGHT 3TAGES ITANP  I  P  I DEG  COSP  I  0 ;COSP  I =                                             &)'52%   #/2$)# ALGORITHM FLOW CHART     
 and Remote Sensing , vol. 38, pp. 710–719, 2000. 
 } }} JKRP   #OMBINING %QS  AND  YIELDS THE EQUIVALENT SURFACE CURRENT *AT AREA D!  *N ( V V N E D ! R r  
 ELECTRONIC COUNTER-COUNTERMEASURES  24.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24  6. Digital receiver channel errors such as ADC quantization, sample/hold jitter, and  digital converter offset67,68  7. The pulse width that limits the reaction time of the adaptive system, in order to  avoid the cancellation of target signal  8. 
    %3! 3!2S HAVE MAINTAINED A CONTINUOUS RECORD OF OUTSTANDING PERFORMANCE %23 
 The 'first sidelobe is 17.5 dB below the main lobe, and  the heamwidth is 58.5,l./D.  The e!Tect of tapering the amplitude distribution of a circular aperture is similar to  tapering the distrihution of a linear aperture. The sidelobes may be reduced, but at the expense  of broader beamwidth and less antenna gain. 
 EMITTER JUNCTION 4HIS COMPARES TO THE OPERATION OF A FIELD EFFECT TRANSISTOR &%4   OR A UNIPOLAR DEVICE  WHERE CHARGE IS CARRIED WITH ONLY ONE TYPE OF CHARGE CARRIER 4HE REMAINING TRANSISTOR CONSTRUC 
 Switch S1enables amaintenance man totune the local oscillators manually tothe proper frequencies forsignal reception with P1and Pt (for the search orbeacon local oscillators respectively), and then to revert toAFC operation centered atthecorrect frequency. This switch isspring-loaded sothat the circuit cannot beleft onmanual tuning. Jacks areprovided at“which the radar AFC crystal current and the beacon AFC crystal current can bemeasured. 
 FILTER RECEIVER TYPICALLY USED BY MONOSTATIC RADAR  3UCH CROSS 
 MODE DATA SETS  WHERE EACH SET OF BURSTS CORRESPONDS TO A DIFFERENT RANGE SUB 
 It has been suggested, 26  however, that even with only a five-pulse c·anceler, a five-pulse Chebyshev design provides  significantly wider bandwidth 'tha'n the. five-pulse "optimum" design. To achieve the wider  band the Chebyshev design has··a lower improvement factor (since it is not "optimum"), but in  many cases the trade is worthwhile especially if the clutter spectrum is narrow. 
 SCALE MODEL ARE GUIDED BY THE SAME  IDEAS THAT LED TO THE  TWO 
 Because these absorbers do not rely on the cancellation of a front-face reflection by  a rear-face reflection, they exhibit great bandwidth. In general, a pyramidal absorber  with sharp tips and uniform bulk loss characteristics can have a bandwidth that  exceeds 100:1.60 Nonspecular absorbers need not have the great thickness characterized by specu - lar absorbers. Intended primarily for suppression of surface traveling-wave echoes,  nonspecular materials have the opportunity to reduce the buildup of surface cur - rents over several wavelengths along the surface . 
 U.S. Patent 4,005,415,  Jan. 25. 
 78. Pyati, V. P.: The Role of Circular Polarization in Bistatic Radars for Mitigation of In- terference Due to Rain, IEEE Trans., vol. 
 TION OF WEAK TARGETS IN CLUTTER AND INTERFERENCE ENVIRONMENTS v IN  )%%% )NT 2ADAR #ONF   ,ONDON     PP n  . ,EVINE  h! NEW TECHNIQUE FOR INCREASING THE FLEXIBILITY OF RECURSIVE LEAST SQUARES SMOOTHING v  "ELL 3YSTEM 4ECHNICAL *OURNAL  PP n    7 ' "ATH  - % "ALDWIN  AND 7 $ 3TUCKEY  h#ASCADED SPATIAL CORRELATION PROCESSES FOR DENSE  CONTACT ENVIRONMENTS v IN 0ROC 2!$!2     PP n  2 * 0RENGAMAN  2 % 4HURBER  AND 7 ' "ATH  h! RETROSPECTIVE DETECTION ALGORITHM FOR EXTRAC 
 Although IIR fil - ters are almost never used in radar systems for these and a variety of historical reasons, a  cautious designer might find an application where they can be used to good advantage. By contrast, FIR filters are inherently stable. Real FIR filters with symmetric coef - ficients automatically provide a linear phase shift over frequency, introducing little or  no phase distortion to the filtered signal, which is highly desirable in many applica - tions. 
 and Remote Sensing , vol. 29, pp. 111–450, 1991. 
 LANCE RADAR  A NUMBER OF RECEIVER GATES ARE USED TO DETECT TARGETS THAT MAY APPEAR AT ANY RANGE WITHIN THE INTERPULSE PERIOD &IGURE  ILLUSTRATES THE GENERAL CASE WHERE THE GATE SPACING  S S  THE GATE WIDTH  SG  AND THE TRANSMITTED PULSE  ST ARE ALL UNEQUAL 3ELECTING  ST   SG MAXIMIZES TARGET RETURN SIGNAL 
 22-24, 1975, Houston, Texas, pp. 504 507.  77. 
 DOMAIN PROCESSING IS USED TO IMPLEMENT THE CONVOLUTION 4HE FREQUENCY 
 The impact on the solid- state transmitter designer of the requirement for high radiated power is fundamental: high power must be achieved by combining the outputs of lower- power amplifiers in order to develop the required radiated levels. The amplifier- combining approach generally takes one of two different configurations: space- combined or corporate-combined structures, as shown in Fig. 5.6; however, there are also hybrid approaches in which corporate-combined modules feed (b) FIG. 
 44.Milne,K.:TheCombination ofPulseCompression withFrequency Scanning forThree-dimensional Radars.TheRadioandElectronic Engr.,vol.28.pp.89-106. Au~ust. 1964.. 
 G. D. Thayer. 
 Another method of producing surface-based ducting conditions is by divergence  (spreading out) of relatively cool air under a thunderstorm. While this method may not  be as frequent as the other methods, it may still enhance surface propagation during  the thunderstorm activity, usually on the order of a few hours. With the exception of thunderstorm conditions, surface-based ducting is associ - ated with fair weather and with increased occurrence of surface-based ducts during  the warmer months and in more equatorial latitudes. 
 The algorithm consists of two parts. In the ﬁrst part, calculations of time delays, tg(p)= Rg(p)/c, for each g∈G, of signals reemitted by asteroid’s scattering points and their arrangement in ascending order, g=0,G−1,a r e performed. In the second part, the asteroid’s ISAR signal modeling in accordance with the expression (7) is accomplished. 
 D., et al.: First Experimental Results for the Valley Forge Radio Camera Program, Proc. IEEE, vol. 67, pp. 
 Trunk and B. H. Cantrell, “Angular accuracy of a scanning radar employing a 2-pole integra - tor,” IEEE Trans ., vol. 
 .EIGHBOR '..  4ECHNIQUE AFTER    ( ,EUNG ET AL Ú )%%%  . Ç°Ó{  2!$!2 (!.$"//+  &)'52%  3TRUCTURE OF AUTOMATIC TRACKING PROCESS . 
 WAY ANTENNA FIELD  INTENSITY 4HE PHASE ADVANCE IS  HPPQ L  F464 DPXPSIN    WHERE FD   DOPPLER SHIFT OF SCATTERER %Q    4P   INTERPULSE PERIOD &IGURE B SHOWS A METHOD OF CORRECTING FOR THE PHASE ADVANCE  G !N IDEALIZED  CORRECTION SIGNAL  %C IS APPLIED  LEADING THE RECEIVED SIGNAL BY n AND LAGGING THE NEXT  RECEIVED SIGNAL BY n &OR EXACT COMPENSATION  THE FOLLOWING RELATION WOULD HOLD  %%64 CXP   £TAN   TANSINHQPQ L   4HIS ASSUMES A TWO 
 t\targetathighelevation anglescompetes withsurfaceclutteratlowangles.Increasing the antenna gainathighanglcsbutnotatlowangleswilltherefore improve thetargetechowith respecttothcc1uHer.9A ](C~!(A'l,tfso'd01:"1 lA"'Ic·~ ;-," O(l~ (\(...A,.rl~ a.,.(.l(,<,' ,.' FiIitIlH'7.27Antcnna e1cvation pallcrnforalong-range air-search radartoachievehigh-angle coverage whenSTCisemployed. (a)Comparison withthecosecant-squared pattern;(b)free-space coverage diagram. (FromSIJrader,97 courtesy McGraw-Hill BookCompallY.). 
 Contents About the Special Issue Editor ...................................... vii Fabio Bovenga Special Issue “Synthetic Aperture Radar (SAR) Techniques and Applications”Reprinted from: Sensors 2020 ,20, 1851, doi:10.3390/s20071851 .................... 1 Wensheng Chang, Haihong T ao, Guangcai Sun, Yuqi Wang and Zheng Bao A Novel Multi-Angle SAR Imaging System and Method Based on an Ultrahigh Speed Platform Reprinted from: Sensors 2019 ,19, 1701, doi:10.3390/s19071701 .................... 
 TO 
 POLARIZED MODES  p AND EXPERIMENTAL OR DEMONSTRATION MODES INCLUDING 3POT3!2  4HE , BAND  CM  BASELINE FREQUENCY  -(Z  HAS TWO BANDWIDTHS   -(Z FINE 
 This increase indrag isdue totheinterference and stagnation points setupby mounting theairfoil totheplane. Anadditional feature ofthis radome was that itwas designed tobedeiced bymeans ofhotair. The optimum wall spacings forheat transfer and forelectrical transmission donot coincide, sothat deicing isnot very efficient. 
 (6.53) In the extreme case where Mf does not contain the factor 2, this creates a spurious fre - quency spacing of fclk / 2Nf. For example, with a 1 GHz clock and 32-bit frequency accu - mulator, the spurious frequency spacing can be as close as 0.23 Hz. In most cases, such  closely spaced spurious signals cannot be differentiated from noise. 
 Sensors 2019 ,19, 1649. [CrossRef ][PubMed ] 7. Lazarov, A. 
  
 This derivation assumes a  linear system. That is, it is assumed that the voltage envelope of the echo signals, as the  antenna scans past a point target, is identical to the two-way antenna voltage pattern.  This assumption of a linear system may be unrealistic for some practical MTI systems  with relatively few hits per beamwidth, however, as discussed in Section 2.11. 
 When there is an average of NC  detections in a D-dimensional region G, then73  E[NFT] = lF × l�pM−2 × N M C × g�(D, N, M) (7.40) ch07.indd   42 12/17/07   2:14:45 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 '(Z SCATTERING COEFFICIENT VERSUS SOIL MOISTURE PERCENT OF FIELD CAPACITY  FOR  VEGETATION 
  
 Siegel: Studies in Radar Cross-Sections XV: Radar  Cross-Sections of the B-47 and B-52 Aircraft, Univ. of Michigan, Radiation Laboratory Report  2260-1-T, August 1954 (unclassified), AD 46 74l.  65. 
 G. Scott: The Parabolic Dome Antenna: A Large Aperture,  360 Degree, Rapid Scan Antenna, IRE WESCON Co11v. Record, vol. 
 The performance of the primary system varies from that of a triple canceler to a level less than that of a double canceler. The secondary-system performance varies from that of a triple canceler to a performance level lower than that of a single canceler. 76.77 DETECTIONOFGROUNDMOVING TARGETS Vehicles and ships may have radial speeds that are significantly greater than the clutter velocity spectrum. 
 Maguire, W. W.: Application of Pulsed Doppler Radar to Airborne Radar Systems, Proc. Nurl. 
 By the end of 2006, RADARSAT-1 had completed its 11th year, logging more  than 60,000 orbits and collecting enough data to map the entire surface of the Earth  an equivalent of 130 times. The Canadian Ice Service relies on RADARSAT-1 data  for its routine operations, which require more than 3000 frames of data per year. Since  the SAR is the only RADARSAT-1 payload instrument, a sun-synchronous, dawn- dusk orbit was chosen to maximize illumination of the solar panels, which allows  20 minutes of SAR operation per orbit. 
 This course is different from those usually found in most graduate electrical  engineering programs. Typical EE courses cover topics related to circuits, components, de­ vices, and techniques that might make up an electrical or electronic system; hut seldom is the  student exposed to the system itself. It is the system application (whether radar, communica­ tions, navigation, control, information processing, or energy) that is the raison d'etre for the  electrical engineer. 
 Lossintroduced toattenuate thebackward wavealsoreducesthepoweroftheforward wave. whichresultsinalossofefficiency. Thislossintheforward wavecanbeavoided bytheuseof discontinuities calledsel'ers.whichareshortinternal terminations designed todissipate the reverse-directed powerwithout seriously affecting theforward power.13Thenumberofsevers depends onthegainofthetube;oneseverisusedforeach15to20dBofgain.Inaddition to reflection-type oscillations, backward-wave oscillations canoccur.Thesefrequently occur outside thepClssband sothattheycanbereduced bylossthatisfrequency selective. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar.  SYNTHETIC APERTURE RADAR  17 .156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 Skolnik21 continues, “When a SAR images the ground from an elevated platform,  the unambiguous range can correspond to the distance between the forward edge and  the far edge of the region to be mapped. 
 R. J. Mailloux, “Phased array theory and technology,” Proc. 
 The accuracy of the range measurement improves as the FM slope increases since the observed frequency differences can be more accurately measured. However, the FM slope is limited by clutter-spreading considerations since dur- ing the FM periods the clutter is smeared in frequency and can appear in fre- quency regions normally clear of clutter. Range accuracies on the order of 1 or 2 mi can be reasonably achieved. 
 Since the radio-frequency energy makes a round trip, only half thetime of travel determines the distance to the target. The round trip time isaccounted for in the calibration of the radar. The speed of a pulse of radio-frequency energy is so fast that the pulse can circumnavigate the earth at the equator more than 7 times in 1 second. 
 Fourier-integral synthesis. The Fourier-integral relationship between the field-intensity pat-  tern and the aperture distribution was discussed in Sec. 7.2. 
 Thefunction oftheantennaduringtransmission istoconcentrate theradiated energyintoashapedbeamwhichpointsinthedesireddirection inspace.Onreception theantenna collectstheenergycontained intheechosignalanddelivers ittothereceiver. Thustheradarantenna iscalledupontofulfillreciprocal butrelatedroles.In theradarequation derivedinChap.1[Eq.(1.7)]thesetworoleswereexpressed bythetrans­ mittinggainandtheeffective receiving aperture. Thetwoparameters areproportional toone another. 
 Other module features include automatic fault detection and shutoff, harmonic filtering, and factory-adjustable delay line for module insertion phase matching. RAMP. The RAMP (Radar Modernization Project) radar system is an L- band system built by the Raytheon Company to replace the earlier primary and secondary surveillance radars used for air traffic control by Canada's Ministry of Transport.25'26 The primary surveillance radar consists of a rotating reflector, horn-fed by a solid-state transmitter, and redundant receive channels with receiver-exciters and signal processors. 
 With linear po larization,  the polarization is defined by the situation of the electrical field vector in the incident plane.     Figure 2.3  Polarization defined incident Waves. (a) Parallel Polarization (b) Perpendicular  Polarization   The electric field can show a tangent ial component E 1tan and a perpendicular component E 1norm   in regard to the interface. 
 - Ê",Ê7 
 L. O. Eber and H. 
   2!$!2 #2/33 3%#4)/.   £{°x &ORWARD SCATTERING IS A SPECIAL CASE OF BISTATIC SCATTERING IN WHICH THE BISTATIC ANGLE IS  n WHENCE THE DIRECTION OF INTEREST IS ALONG THE SHADOW ZONE BEHIND THE TARGET 4HE SHADOW ITSELF CAN BE REGARDED AS THE SUM OF TWO FIELDS OF NEARLY EQUAL STRENGTH  BUT n OUT OF PHASE /NE IS THE INCIDENT FIELD  AND THE OTHER IS THE SCATTERED FIELD  4HE FORMATION OF THE SHADOW IMPLIES THAT THE FORWARD SCATTERING IS LARGE  WHICH IS INDEED THE CASE 4HE FIELDS BEHIND THE TARGET ARE HARDLY EVER PRECISELY ZERO  HOWEVER  BECAUSE SOME ENERGY USUALLY LEAKS INTO THE SHADOW ZONE VIA DIFFRACTION FROM THE SIDES OF THE TARGET %XAMPLES OF 2#3 #HARACTERISTICS   4HE DISCUSSION OF RADAR CROSS SECTION CHAR 
 Processing times. Image Name [Rows, Cols] (Complex) Proc. Time [s] Caramanico 1 [2001, 4001] 21.049431 Caramanico 2 [2001, 4001] 20.528043 Flevoland [1101, 5000] 13.358860 Matera [2048, 2048] 10.970114 Simulated Pulse [776, 2001] 2.473084 99. 
 CUSSED PREVIOUSLY3,!2  M  $"3  M  5NFOCUSED STRIPMAP 3!2  M3TRIPMAP 3!2  M  3POTLIGHT 3!2  M  £Ç°{Ê -,Ê, 
 E. Collin and F. J. 
 IAN SPECTRAL ROLL 
 Goj, Synthetic Aperture Radar and Electronic Warfare , Dedham, MA: Artech House, Inc., 1989. 165. C. 
 Very powerful radars of this type are referred to as Mesosphere, Stratosphere,  Troposphere (MST) radars because of their ability to make measurements throughout  most of these atmospheric regions up to 60–100 km in altitude. Several major MST  radar facilities located at facilities around the world operate at VHF frequencies around  50 MHz and observe upper atmospheric (tropospheric and lower stratospheric) winds  or the higher level stratospheric and mesospheric winds. Shorter wavelength UHF wind  profilers operating at 400–450 MHz sense atmospheric winds up to 20–25 km and these  “tropospheric wind profilers” are the most widely used for operational weather obser - vations. 
 R. K. Moore et al., “Simultaneous active and passive microwave response of the Earth—the  Skylab RADSCAT experiment,” in Proc. 
 The received signal strength also varies from O to 16; hence the fourth-power relation  hetween range and echo signal results in a variation of radar range from Oto 2 times the range  of the same radar in free space.  The field strength is a maximum when the argument of the sine term in Eq. (12.5) is equal  to n/2, 3rr/2, ... 
 Digital filters can be either Finite Impulse Response (FIR) or Infinite Impulse  Response (IIR). FIR filters are typically preferred as their finite response is desirable  along with their linear phase characteristic. Phase linearity is achieved with the sym - metric impulse response condition9 defined by Eq. 
 VOLTAGE CONTRIBUTIONS FROM EVERY ELEMENT IN THE ARRAY OR AT LEAST THOSE IN THE IMMEDIATE VICINITY  WOULD BE ADDED VECTORIALLY TO PRODUCE THE VOLTAGE REFLECTED BACK TOWARD THE GENERATOR )N A PRACTICAL ARRAY  THE IMPEDANCE VARIATION DEPENDS UPON THE FEED SYSTEM AND THE PHASE SHIFTER )F THESE ARE TAKEN INTO ACCOUNT  THE IMPEDANCE VARIATION MAY BE DIFFERENT FROM WHAT THE ABOVE MODEL MIGHT PREDICT )N MOST ANALYSES  ONLY THE COUPLING AT THE APERTURE IS CONSIDERED 4HIS DESCRIP 
 The ESM receiver is used to control the deployment and operation of ECM; the link between ESM and ECM is often automatic. A single received radar pulse is characterized by a number of measurable pa- rameters. The availability, resolution, and accuracy of these measurements must all be taken into account when designing the deinterleaving system because the approach used depends on the parameter data set available. 
 If,now, apositive trigger pulse ofsufficient voltage isapplied togl(oranegative pulse tog,) theamplified pulse isapplied toVzthrough C,and V2starts tocut ofi.. 500 THERECEIVING SYSTEM—INDICATORS [%C13.7 The drop initscurrent further reduces the bias onVI,and there isa violent regeneration which ends with V1fullonand thegrid ofVzfarpast cutoff. The grid ofVzthen experiences anexponential recovery toward B+, and when the cutoff point isreached regeneration occurs inthe opposite direction and restores theinitial condition. 
 UNIT GRADIENTS &ROM &IGURE   IT CAN BE SEEN  THAT THE DUCT EXTENDS FROM THE TOP OF THE TRAPPING LAYER DOWNWARD UNTIL IT INTERSECTS WITH THE - 
 (14.37)  where O is the grazing angle in degrees and ,l is in centimeters. Thus, a-0 increases with  increasing frequency. Vertical polarization produced echos 3 to 4 dB greater than horizontal  polarization. 
 OFF IN SIGNAL STRENGTH AT RANGES BEYOND A FEW HUNDRED KILOMETERS  WHERE  D" OF EXTRA TRANSMIT POWER MAY BUY ONLY ON THE ORDER OF  KILOMETERS OF ADDITIONAL DETECTION RANGE ! MORE WIDELY USED PROPAGATION CODE IS '27!6%   WHICH EMPLOYS DIFFERENT  MATHEMATICAL REPRESENTATIONS FOR THE FIELD  DEPENDING ON RANGE AND OTHER PARAMETERS  SO AS TO MAXIMIZE COMPUTATIONAL EFFICIENCY 3OME INDICATION OF THE ACCURACY OF THIS MODEL 4!",%  3PECIFICATIONS OF  3%#!2  AN (& 3URFACE 7AVE 2ADAR $ESIGNED FOR 3URVEILLANCE OF  THE  NMI %XCLUSIVE %CONOMIC :ONE 2ADAR 3%#!2 -ANUFACTURER $ARONMONT 4ECHNOLOGIES 4YPE "ISTATIC (& SURFACE WAVE RADAR 4X 
  
 Binary moving-window detector.39·52-60 As a radar antenna scans by a target it will normally  receive n echo pulses. If m of these expected n pulses exceed a predetermined value (threshold),  a target may be declared to be present. The use of a criterion that requires m out of n echo  pulses to be present .is a form of integration. 
 An example trajectory is shown in Fig. 18.22 for an aircraft fly- ing a straight course past the radar with a minimum distance R0 at altitude h. The figure shows that minimum range and maximum elevation angle occur when the radar is looking normal to the target path. 
 Another method for obtaining 3D coverage with a scanning pencil beam is to employ  helical scan, as in the renowned SCR-584 of World War 11. A single pencil beam is rotated in  azimutll with its elevation angle increased one beamwidtli per revolution so as to trace a  helical pattern. It is a simple technique, but is not of high accuracy since it is dificult to  interpolate between adjacent elevation beam positions. 
 With the use of multiple beams, it is possible to achieve any desired combination of unambiguous range, resolution, and area rate. The antenna area and the number of beams are determined from the perfor- mance parameters. A more complete analysis of multibeam systems is given in Refs. 
 In arrays with a large number of adaptive elements the time required for  the array to converge to the desired aperture illumination can be relatively long. The conver­ gence time can be reduced at the cost of hardware complexity. The complexity of the adaptive  mechanization and the speed of convergence limit the practical utility of the large adaptive  array. 
 2ESOLUTION 2ADAR   .EW 9ORK -C'RAW 
           e  #OURTESY OF %DWIN - 7ATERSCHOOT  ,OCKHEED -ARTIN -ARITIME AND 3ENSOR 3YSTEMS  3YRACUSE  .9. 
 If the removed elements (in a regular thinned array) are replaced with elements  with matched loads, the element pattern is identical to that of one in the regular array  with all elements excited. The element pattern is independent of the array excitation,  and the same fractional amount of power will be lost (because of mismatch) whether  the array is thinned, tapered, or uniformly illuminated. It should be noted that the  concept of an element pattern that applies equally to every element is valid only when  isolating feeds are used and edge effects are ignored. 
 £È°£Ó  2!$!2 (!.$"//+  4HUS  THE COMPONENT OF THE SURFACE THAT SATISFIES THE "RAGG RESONANCE CONDITION IS  ,    K SIN P    4HIS MEANS THAT THE MOST IMPORTANT CONTRIBUTOR TO A SURFACE RETURN IS THE COMPONENT OF  SURFACE ROUGHNESS WITH WAVELENGTH  , %VEN THOUGH OTHER COMPONENTS MAY BE  MUCH  LARGER  THE "RAGG RESONANCE MAKES THIS COMPONENT MORE IMPORTANT /N THE OCEAN  THIS  MEANS THAT TINY RIPPLES ARE MORE IMPORTANT THAN WAVES THAT ARE METERS HIGH THE SAME  APPLIES FOR LAND 
 ¤ ¦¥³ µ´ LOG GD"    WHICH IS PLOTTED IN &IGURE  4HESE  CURVES  WHICH APPLY TO ALL MULTIPLE 
 LOCATED WITH THE RADAR ITSELF OR DETECTION OF THE RADARS  EMISSIONS BY AN %LECTRONIC 3UPPORT -EASURES %3-  SYSTEM ÓÈ°xÊ  "  "1-Ê*,"*/" Ó !NOMALOUS OR NONSTANDARD WAVE PROPAGATION USUALLY REFERS TO THE CONSIDERATION OF  NONSTANDARD REFRACTION VERSUS STANDARD REFRACTION 4HESE NONSTANDARD REFRACTIVE CONDI 
 If the MTI filter is tracking the surface clutter, the spectra of the sources with a different mean doppler frequency lie in the passband of the MTI filter. A 20-kn differential in an S-band system corresponds to 200 Hz, which would be at an optimum response in a 400-PRF system. A single-delay secondary canceler can be cascaded with either a single-delay or a double-delay primary canceler. 
 Skillman, Westinghouse Electric Corporation (CHAPTER 17) Merrill I. Skolnik, Naval Research Laboratory (CHAPTER 1) Fred M. Staudaher, Naval Research Laboratory (CHAPTER 16) George H. 
                  
 pp. 1 11 - 121. September. 
 Any use is subject to the Terms of Use as given at the website. Sea Clutter.  SEA CLUTTER  15.436x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 111. K. 
 The noise or clutter fluctuations that appear at the  output of a logarithmic receiver are not symmetrical since the large amplitudes are suppressed  due to the nature of the logarithmic characteristic. To make the output more like that of a  linear receiver, the log-FTC may he followed by an amplifier with the inverse of the logarith­ mic characteristic (antilog). This restores the contrast of the display and eliminates the loss in  detectability associated with the logarithmic characteristic. 
 HALF OF THE VALUE FROM %Q  &EEDBACK  AND  0ULSE 
 A. Woroncow, arid B. R. 
 27.  “The technical characteristics for a universal shipborne automatic identification system (AIS)  using time division multiple access in the maritime mobile band,” ITU Recommendation  M.1371-1, International Telecommunication Union, Geneva. 28. 
 Another effect is related to  FIG.URE 15.18  Effect of ducting on low-angle clutter; wind speed  about 10 kt ( after F . B. Dyer and N. 
 TROLLED TO ASSURE RELIABLE  
 195. Sensors 2019 ,19, 2161 Based on the quantitative analysis from the Monte-Carlo simulation listed in Figure 14, both PSLR and ISLR in azimuth increase with the rising of spectral index, which will distort the azimuth imaging performance and weaken the SAR image contrast. It can be seen from the extended target result that the image blur become more serious with the increase of spectral index. 
 MENT  INCLUDING ULTRAWIDEBAND RADAR OR '02  MUST BE  #ONFORMIT£  %UROP£ENE   #% MARKED TO DEMONSTRATE THAT IT SATISFIES THE RELEVANT DIRECTIVES OF THE %UROPEAN 5NION 4HE #% MARK MAY ONLY BE APPLIED WHEN THE REQUIREMENTS OF ALL OTHER  RELEVANT %5 $IRECTIVES  SUCH AS SAFETY  HAVE ALSO BEEN DEMONSTRATED )N THE 53 THE &## WEB SITE  PROVIDES CURRENT INFORMATION AND THE LIMITS ARE SHOWN IN  &IGURE &)'52%   57" 3!2 IMAGE OF BURIED !4 MINES IN THE 9UMA $ESERT  AIRCRAFT AT  M ALTITUDE  #OURTESY 32) )NTERNATIONAL 53!  $R 2 6ICKERS   . 
 112–114, January 1985. [In the last term of Eq. (15) in this reference,   the dot preceding the minus sign should be deleted and b should be replaced by sin b ; in Eq. 
 Such scanners can bemounted inany ofthelocations that aregood forsector scanners. Bomber-borne scanners forprotective firecontrol arelocated. SEC. 
 Marcum. J. I.: A Statistical Theory of Target Detection by Pulsed Radar, Mathematical Appendix,  I RE Trans., vol. 
 WINDOW INTEGRATOR 4HE OPTIMAL VALUES FOR LOG 
 A Naval Research Laboratory system called TRAKX (Tracking Radar At Ka and  X bands) was designed for instrumentation radar applications for missile and training  ranges.13  Its purpose was to add precision tracking on targets, essentially to “splash”  and provide precision tracking at Ka band in an environment of X-band countermea - sure experiments. ch09.indd   24 12/15/07   6:07:26 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Altogether n,has changed byafactor of&between low and high speed, orbyjust theratio ofthebeamwidth to360°. Ifnow weassume that thesignal power required for detection, &, isproportional tol/fi, aplot ofSm,m against scanning speed will look like Fig. 2“8. 
 All these things have one thing  in common: they depend on pulse transmission, though  not in every case on echo reception.  . X. 
 Kitaigordskii, J. Geophys. Res., vol. 
 0 40 ti  0 C/L 0 dB -c C/L == 10 dB (I)  E  (I) 30 > 0 ... a.  E  20. 
 INSTRUMENTATION RADAR  WHERE TARGET ASPECT  CHANGES CAN CAUSE A LINEARLY POLARIZED BEACON TO ROTATE TO A CROSS 
 An illustration of day-to-day variability is presented in Figure 20.5, which over - lays 30 vertical incidence soundings recorded at the same time of day for a month. 45015 10Plasma frequency (MHz)5 00 4 8 12 Time of day (local)16 20 24400 350 300 250 200 FIGURE 20.4  Diurnal variation of the electron density profile, as measured by the plasma frequency,  plotted for various virtual heights (in km). The data was recorded by a vertical incidence sounder at  latitude 18.0 S, longitude 144.9 E on 17 September 2002, SSN = 88. 
 There are two basic types of space feeds depending on whether they are analogous  to a lens or to a reflector. The lens array, Fig. 8.22, is fed from a primary feed just as a lens  antenna. 
 In early forms of Oboe the amplitude  of these dots and dashes, which can be injected into an  aircraft intercom system, tells the pilot how far he ts  from the correct track. In later versions rate-aiding  principles have been applied, and the amplitude of the  dots and dashes thus tells the pilot, not when he is on  the track, but when his heading is correct—that is, when  he is making accurately towards the desired target or  airfield.  Ground station B, known as the ‘releasing’ (from the * *  days when Oboe was devised as a wartime bomb-aiming  . 
 125-129, American Meteorological Society, Boston, 1980. 16. Allen, R. 
 Optical ﬂow was effective for removing difﬁcult false positives that resulted from registration and perspective problems. Figure 7. Results by ( a) manual ground truth; ( b) NR-ELM; ( c) GaborTLC; ( d) PCAKM; (e) proposed method. 
 QUANTIZATION 
 BEAM NULL   
 LIMITED  TO A SMALL ENOUGH VALUE SO THAT INTERFER 
 17–22. 33. W. 
 In principle, it is possible to determine tlle  trajectory of the target from doppler measurements only.57  Bistatic radar measurements. The measurements made with a bistatic radar art: similar to  those of the conventional monostatic radar except they are usually more complicated and  difficult to accomplish. The measurement of distance relative to one of the sites requires a  knowledge of both the angle of arrival at the receiving site and the distance between transmit-  ter and receiver, as was indicated by Eq. 
 THENATURE OFRADAR3 rangemightresult.Echoesthatarriveafterthetransmission ofthenextpulsearecalled second-time-arOlmd (ormultiple-time-around) echoes.Suchanechowouldappeartobeata muchshorterrangethantheactualandcouldbemisleading ifitwerenotknowntobea second-time-around echo.Therangebeyondwhichtargetsappearassecond-time-around echoesiscalledthemaximum unambiguous rangeandis c Runamb=2fp (1.2) wherefp=pulserepetition frequency, inHz.Aplotofthemaximum unambiguous rangeasa function ofpulserepetition frequency isshowninFig.1.1. Although thetypicalradartransmits asimplepulse-modulated waveform, therearea number ofothersuitable modulations thatmightbeused.Thepulsecarriermightbe frequency- orphase-modulated topermittheechosignalstobecompressed intimeafter reception. Thisachieves thebenefitsofhighrange-resolution withouttheneedtoresorttoa shortpulse.Thetechnique ofusingalong,modulated pulsetoobtaintheresolution ofashort pulse,butwiththeenergyofalongpulse,isknownaspulsecompression. 
 The more accurate equations are given in Ref. 14 and in radio astronomy texts. Available Power, Gain, and Loss. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°Ó REPRESENTING THE DATA  AND SEVERAL ALTERNATIVE METHODS FOR DATA ANALYSIS /NCE MAS 
 02& 2ANGE 7HILE 3EARCH  -273  6ELOCITY 3EARCH  63 IS A HIGH 
 Since the scattering coefficient varies much more rapidly near the vertical than at angles beyond 10 or 20° from the vertical, the problem is much more severe at the vertical. Furthermore, the problem is complicated at the vertical by the fact that the angular scale terminates there, so that a beam centered at the vertical illuminates weaker targets (a0) on both sides of its pattern, whereas a beam away from the vertical illuminates stronger signals on one side and weaker signals on the other. Figure 12.18 shows what happens for a steeply descending curve of <r° versus 0. 
 Magnetic deflection isaccomplished bypassing currents ofthedesired waveforms through acoil orcombination ofcoils surrounding the tube neck (Fig. 13”1). The deflection due toeach coil isproportional tothe current through it,and thecombined deflection isthevector sum ofthe individual ones. 
 LINE TOWERS  AS WELL AS LOW 
 tion will becorrect foronly one sweep speed. 1Except forthisrequirement, thissynchro could have asingle-phase rotor.. 532 THEhzYCEIVI.VGSYSTEM—INDICA TORS [SEC. 
 BOARD THE AIRCRAFT  NET 
 , P1R.9, Albuquerque, 2005. 179. T. 
 The mixer spurious responses just discussed and the stalo and coho problems of Sec. 3.5 represent only the most likely sources of instability to be encountered. Other elements of the receiver require attention to avoid instability problems. 
 For a single radar pulse with a duration of a few microseconds, the doppler shift  due to aircraft target motion is a small fraction of the signal bandwidth, and conven - tional MTI and pulse doppler processing are not applicable. It is well known that the  classical single-pulse “matched” filter provides optimum radar detection performance  when used in a white-noise background. Against clutter returns that have the same  spectrum as the transmitted radar pulse, the matched filter is no longer optimum, but  the potential improvement in the output signal-to-clutter ratio by designing a modified  optimized filter is usually insignificant. 
 Aspace-fed reRectarray withanoffsetfeedisshowninFig.8.23.Theenergyentersthe antenna elements, passesthrough thephaseshifters, isreRected, andagainpassesback throughthephaseshifterstoberadiated. Likethelensarray,thephaseshiftersapplyalinear phasedistribution forbeamsteeringandacorrection forthecurvature oftheprimarywave­ frontfromthehort1.Becausetheenergypassesthroughthephaseshifterstwice,theyneedonly halfthephase-shift capability ofalensarrayoraconventional array;i.e.,180°ofone-way phaseshiftisadequate, ratherthan360°.Thephaseshifters,however, mustbereciprocal. As withtLelensarray,multiple beamscanbegenerated withadditional feedhorns. 
 TIME 
 During the 1980s and 1990s, phase shifter and T/R module technology greatly matured  and ESA costs dropped dramatically. These advances have resulted in increased inter - est and utilization of ESAs for wide scan radar applications, and array-fed reflectors  where limited electronic scan suffices. Advantages and Applications of the Radar Reflector Antenna. 
 2ADAR  3ONAR .AVIG   VOL   NO   PP n   /CTOBER   & % .ATHANSON   LOC CIT  3EC .   3%! #,544%2  £x°{£  7 # +ELLER  7 * 0LANT  AND ' 2 6ALENZUELA  h/BSERVATION OF BREAKING OCEAN WAVES WITH COHER 
 Runaway tracks are false tracks whose high speed causes them to rapidly move away from the true target position. They can asso- ciate with other reported positions or false alarms and thus perpetuate them- selves. Since ground traffic is not of interest in the AEW case, these undesired targets are censored on the basis of highway grid maps, the small change in range during the antenna dwell, or the small velocity determined by a scan-to-scan pro- cessor or the tracking system. 
 W. Stimson, Introduction to Airborne Radar,  Chapter 3 & Part X, 2nd Ed., Raleigh, NC:  SciTech Publishing, Inc., 1998. ch04.indd   49 12/20/07   4:54:09 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
  
 28 to 16.29 sea ice, 16.44 to 16.46 snow, 16.42 to 16.44 soil moisture, 16.40 to 16.41 speckle, 16.55 theoretical models, 16.7 to 16.12 vegetation, 16.41 Ground moving target indication (GMTI), 5.38 to 5.42, 17.25 Ground moving target thresholding, 5.39 to 5.40. Ground moving target track (GMTT), 5.38 Ground moving target weapon delivery, 5.40 to 5.41 Ground penetrating radar (GPR) antennas, 21.24 to 21.30 applications of, 21.3, 21.35 to 21.40 archeological applications, 21.36 and land mines, 21.37 AT mines, 21.34, 21.39 attenuation with, 21.7 to 21.9 bandwidth, 21.1 characteristics of, 21.4 clutter in, 21.5, 21.10 comparison with optical image, 21.4 depth resolution, 21.11 description of, 21. 1 to 21.6 dispersion in, 21.11 earth material properties, 21.18 to 21.19 example of, 21.2 forensic investigations, 21.35 and frequency domain, 21.23 and glacier, 21.37 image processing, 21.30 to 21.35 licensing of, 21.39 to 21.40 modeling of, 21.13 to 21.18 modulation techniques, 21.21 to 21.24. 
 In Wastiing-  ton. D.C., a rainfall rate of 0.25  mm/h is exceeded 45'' h!yr, 1 mmjh is  exceeded 200 h!yr. mm/h is exceeded  60 111yr. 
 ATED BY A LONG SOLENOID THAT HAS IRON SHIELDING AROUND ITS OUTSIDE DIAMETER  OR BY A LIGHTER WEIGHT PERIODIC 
 ICE  AGRICULTURE  AND FORESTS  AMONG MANY OTHERS 4HE SEA 
 The variation  in s″c(t) is much greater with the crossed dipole antenna than the parallel dipole. The  ground impulse response  sg(t) can be determined from its attenuation and dielectric  constant across the frequency range of interest. The target impulse response can be composed of the convolution of the wanted  target response, together with many other reflectors, which may not be wanted by the  user but which are valid reflecting targets as far as electromagnetic waves are con - cerned. 
 MONOSTATIC EQUIVALENCE THEOREM USED TO MODEL THE 2#3 OF SOME TARGETS  IS NOT GENERALLY USEFUL FOR CLUTTER MODELING  EXCEPT TO INDICATE AN UPPER LIMIT TO  R"  IN SOME REGIONS&)'52%   #OORDINATE SYSTEM FOR BISTATIC CLUTTER   MEASUREMENTS  PI   INCIDENT ANGLE IN  XZ PLANE    PS   SCATTERING ANGLE IN PLANE CONTAINING  Z AXIS  AND   E   OUT 
 Spizzichino: .. The Scattering of Electrom,ignetic Wav.:s from Rough Sur­ faces," The Macmillan Company, New York. 1963. 
 Large  number of range ambiguities  preclude pulse delay ranging.  High stability requirements due  to range folding. ch04.indd   3 12/20/07   4:51:49 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The Canada Centre for  Remote Sensing (CCRS) has made numerous airborne and ground-based scatterom - eter measurements,26,27 especially over sea ice. The Environmental Research Institute  of Michigan (ERIM),28 CCRS,29 the European Space Agency (ESA),30 and the   Jet Propulsion Laboratory (JPL)31 used imaging synthetic aperture radars (SARs) for  some scattering measurements, but most were not well calibrated. Since the advent  of spaceborne SARs (SIR A, B, and C; ERS 1 and 2; Radarsat; Envisat; JERS-1; and  others), hundreds of papers have appeared dealing with measurements of scattering  and radar applications. 
 213 220.  31. Croncy, J.. 
 L.. and J. Stangel: The Dome Antenna, Microwar•e J., vol. 
  D" ON THE ABSCISSA UNTIL IT  INTERSECTS THE  CURVE &ROM THIS INTERSECTION  DRAW A HORIZONTAL LINE AND READ THE VALUE OF -33,  IN THIS CASE  
 RATE MEASUREMENTS THAN THOSE RELATED TO SIMPLE REFLECTIVITY "RINGI AND #HANDRA  GIVE THE  FOLLOWING RAIN 
 SCATTER 2#3 ROLLOFF CONTINUES   WITH SIDELOBES APPROXIMATING SIN  XX OVER THE FORWARD 
  
 C. G. Bachman, Radar Targets , Lexington, MA: Lexington Books, 1982, p. 
 NOISE MODULATION  AFFECTS SCAN 
 1947. sec. 6.12. 
 In Equation (11.11) the complete mathematical model is given in matrix form.   The Equation (11.11) is not suitable to demonstrate the physical interpretation of the errors, as well as the vectorial corre ction.  A form often used in scattering parameter technology, as such  to represent graphical relationships, is the signal flow graph according to Mason. 
 The ARSR-3 has an instrumented range of 200 nmi. and is required to detect a 2 m2  cross-section target with a single-scan probability of detection of 0.8 and a false alarm proba­ bility of 10-6. The greater the radar range the fewer the number of radars required lo cover a  specified area. 
 SIDELOBE DISTRIBUTION "Y SUITABLE CHOICE OF SHAPE  THE APPARENT FOCAL LENGTH CAN BE ENLARGED SO THAT THE FEED SIZE IS PRACTICAL OR EVEN FEASIBLE 4HIS IS SOME 
 TIZATION 0ROVIDED THAT THE INPUT SIGNAL IS SUFFICIENTLY LARGE RELATIVE TO THE QUANTIZATION SIZE AND UNCORRELATED TO THE SAMPLING SIGNAL  THE QUANTIZATION ERROR IS ESSENTIALLY RAN 
 FIELD EFFECT OF ERRORS ARE BASED ON THE FACT THAT ANTENNAS ARE  LINEAR DEVICES 4HAT IS  THE FAR 
 BAND CARRIER LINES IN 46 TRANSMISSIONS AND RANGEDOPPLER EXPLOITATION OF THE WIDER BAND  NOISE 
 24.52  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 design of a pipelined all-digital image synthesizer capable of generating false-target  images from a series of intercepted ISAR chirp pulses, thus providing RF imaging  decoy capability. The image synthesizer modulates the phase samples from a phase  sampling DRFM that stores intercepted ISAR pulses. The image synthesizer must also  synthesize the temporal lengthening and amplitude modulation caused by the many  reflective surfaces of a target and must generate a realistic doppler profile for each sur - face. 
 5. Smith, W. A.: Ring-Tuned Agile Magnetron Improves Radar Performance, Microwave System News,  vol. 
 SCAN AREA AT A PARTICULAR RANGE OF DEPTHS   IT IS NECESSARY TO INTERPRET THE RADAR IMAGE AS BEING GENERATED BY A PHYSICAL STRUCTURE 4HIS IS NOT ALWAYS EASY IN THE CASE OF A CLUTTERED IMAGE  AND A GREAT DEAL STILL DEPENDS ON THE FIELD EXPERIENCE OF THE OPERATOR %XAMPLES OF UNPROCESSED " 
 Each element points in a different  tiircct iori Tliuq cotlll~r~tatiotls of patterris rnust include both element and array together  Ariotller dillicul~y is t11i11 tllc phase ac well as tlie magnitude of the elenierit pattern varies with  positiorl As a result of the cylirldrical geometry, the radiation pattern is only partially separ-  ;~l~lc ill <p;~tt;~l ~oor(Iirl;~f~s. (It ci111 I)c co~~si~ierecl ;IS tlie procfuct of a ring-array patlcrti ;111cl n  liriear-array pat tcrr~.) 'I lie aziniu t li pattern of a vertical cylindrical array changes with both  a7i11iuth arid elevatiori as tlie bearn is scar~ned in elevation. The far-out sidelobes of a cylindri-  cal array are gcrierally large arid broad ill angle, as conipared to those of a planar array. 
 27-32, July, 1962.  188INTRODUCTION TORADAR SYSTEMS 41.Barton,D.K.,andH.R.Ward:" Handbook ofRadarMeasurement," Prentil:e-llall, Inl:.,Englewood ClilTs,N.J.,1969. 42.Barton, D.K.:"Radars, vol.4,RadarResolution andMultipath Effects," Artel:hHouse,Inc., Dedhum, Muss,1975.(collection of3!lreprints.) 43.Howard, D.D.,J.Nessmith, andS.M.Sherman: Monopulse Tracking ErrorsDuetoMultipath, IEEEEASCON '71Record,pp.175-182. 
 Lab. Memo. Rept. 
 FORMING THE  
 Meteor. Soc ., vol. 83,   pp. 
    PP n  -ARCH     $ * -C,AUGHLIN  9 7U  7 ' 3TEVENS  8 :HANG  - * 3O WA  AND " 7EIJERS  h&ULLY POLARI 
 CRETES ARE THE GUARD CHANNEL AND POSTDETECTION SENSITIVITY TIME CONTROL 34#  4HESE ARE DISCUSSED IN THE PARAGRAPHS THAT FOLLOW 'UARD #HANNEL  4HE GUARD CHANNEL MECHANIZATION COMPARES THE OUTPUTS OF  TWO PARALLEL RECEIVING CHANNELS  ONE CONNECTED TO THE MAIN ANTENNA AND THE SEC 
 Several sources of ambient, or external, noise are de~cribed in this  section.  Cosmic noise48·49 There is a continuous background of noiselike electromagnetic radiation  which arrives from such extraterrestrial sources as our own galaxy (the Milky Way), extraga­ lactic sources, and "radio stars." ln general, cosmic noise decreases with increasing frequency  and can usually be neglected at frequencies above L band. It can be a serious limitation,  however. 
 PULSE STAGGERING IS USED WITH -4) PROCESSING  WHEREAS DWELL 
 FIG. 8.3 Block diagrams of various detectors. The letter C indi- cates a comparison, T is a delay, and loops indicate feedback. 
 Ksienski: Identification of Complex Geometrical Shapes by Means of Low-  Frequency Radar Returns, The Radio and Electronic Engineer, vol. 46, pp. 472-486, October, 1976. 
 20.)SOUT AZOUT ELOUT AOUT LOGAMPSDETUP DOWNLEFTRIGHTDETLOGAMPS DISPERSIVEDELAYFILTER WB FIL.NB FlL.WB FIL.NB FIL. 2dLO ATTENUATORATTENUATOR IFAMPIFAMP LOCONTROL LOWIDEBANDMIXER WIDEBANDMIXERSWITCH SWITCH FIL.FIL.FIL.FIL.FIL.FIL.FIL.FIL. SWITCH SWITCHRFPREAMP RFPREAMPATTENUATORATTENUATORMODE-FORMINGPROCESSOR DUAL-MODESPIRAL . 
 Loss introduced to attenuate the backward wave also reduces the power of the forward wave,  wtiich results in a loss of efficiency. This loss in the forward wave can be avoided by the use of  discoritiniiitics called set-ers, which are short internal terminations designed to dissipate the  reverse-directed power without seriously affecting ttie forward power.13 The number ofsevers  depends on tlie gain of the tube; one sever is used for each 15 to 20 dB of gain. In addition to  reflection-type oscillations, backward-wave oscillations can occur. 
 Each cell in the grid might be 64 × 64 range-doppler bins with 256  grid cells total. Some grid locations close to main-beam clutter (MLC in figure) are  used for forming main-beam clutter discriminants only and are otherwise discarded.  The bins (642 in the example) in each grid cell are ensemble averaged (EA) in sum and  difference channels. 
 The grid  condenser then discharges through the leak R until the  valve’s grid voltage is once more sufficiently in the  positive trend to allow oscillation to commence again.  At once the grid voltage builds up negative, the grid  condenser again discharges through the leak, and so the -  cycle continues.  _ Flyback suppression is sometimes added to a radar  . 
 For an equal-line-length feed, the beam shape will be undistorted (in sine  space) and the beam will move toward broadside as the frequency is increased. If the  phase shifters are replaced by time-delay networks, then the phase through the time- delay networks will change with frequency and the beam will remain stationary . When phase shift (independent of frequency) is used to steer the beam, the beam is  steered to a direction q0 with a phase of  ψπ λπ= =2 2 10 1 0x x cf sin sin q q  on the element located a distance x from the array center. 
 Our  electron tape-measure is now ready for action. Cal is  switched off, and the radar receiver instead put direct  on to the Y plates. If any ship or aircraft is within our  range, and within the direction of our aerials, we shall  see the homecoming echo displayed as a small blip, or  deflection, somewhere along the time-base line. 
 (More details concerning weighting are given in Section 17.6.) There are at least two mathematically equivalent ways of considering SAR. As we have  developed the concept so far, the crossrange resolution may be considered to result from the  doppler shifts resulting from the different apparent line-of-sight velocities of different parts  of the scene. However, the crossrange resolution may also be considered to result from the  large synthetic aperture, much as fine crossrange resolution would also result from a large  real aperture. 
 PASS FILTERED  AND DECIMATED TO PRODUCE )1 DIGITAL DATA 4HE SIGNAL SPECTRUM AT EACH STAGE OF THE PROCESS IS SHOWN IN &IGURE  )N CONTINUOUS 
 The most remarkable feature of the SR-71 is the chine that runs from the nose to the  root of the delta wing. In the nose-on sector, the radar echo will be dominated by  returns from the engine inlets where the chine contribution is no doubt negligible.  When seen from the broadside aspects, the chine reduces the specular echo that would  have come from the otherwise rounded sides of the forward fuselage. 
 #ONTROL 2ADAR 0ULSE $OPPLER 7AVEFORM 02& 4RANSMIT $UTY #YCLE -EDIUM 02&    
 (Copyright 1984, IEEE; from Ref. 37.) Detection Summary. When only 2 to 4 samples (pulses) are available, a binary integrator should be used to avoid false alarms due to interference. 
 However, the added complexity  and lorlger convergerlce time that accompanies the greater degrees of freedom of the large,  fully adaptive array has been a burden that is difficult to justify on a cost-effective basis for  general application.  The objeL(tive of the usual adaptive antenna or the coherent sidelobe canceler is to adjust  the sidelobe levels to minimize the effects of noise or other unwanted signals. If the radar  application allows the use of antennas with extremely low sidelobes, the same result will be  achieved as with the adaptive antenna. 
 Microw. Theory T ech. 2001 ,49, 1581–1592. 
 The  antenna horizontal length might be 300 m or greater. The transmitted waveform can be pulse,  CW, FM-CW, FM (chirp) pulse, or other pulse-compression coded waveforms. Pulsc conl-  pression is used for the same reason as in microwave radars. 
 Hanson, and J. L. Lloyd, “Virtual  path tracing for HF Radar including an ionospheric model,” Naval Res. 
 The work ofthe filter officer called foraconsiderable under- standing ofthe performance ofCH stations, and anappreciation ofthe good and bad qualities ofeach individual installation. Established tracks onthe filter-room board were telephoned bya teller toasecond plotting board maintained inan‘‘operations room. ” Here thefiltered radar tracks were combined with plots oftheObserver Corps (visual airplane spotters), and with fixes made bymeans ofradio direction finders, Inthis main control room, theaim was todisplay the whole ofthepicture oftheair\var; alloperations were generally directed. 
 ”Some sort ofswitch, such asagas-filled tube, serves totransfer control tothesingle-speed unit when theerror becomes large enough toconfuse thehigher-speed servo. For further information ontheextensive subject ofelectromechanical repeaters, thereader isreferred toVol. 21ofthis series. 
 A narrow pulse contains a large number of frequency components with a precise phase relationship be- tween them. If the relative phases are changed by a phase-distorting filter, the frequency components combine to produce a stretched, or expanded, pulse. This expanded pulse is the pulse that is transmitted. 
 M 
 In addition,  the radar operator needs a model with enough sophistication to permit full interpreta - tion of the real-time soundings for operating parameter selection, signal processing,  and data analysis. With this latter requirement, a statistical description is usually not  adequate, as important features may be lost. For example, under rapidly changing  ionospheric conditions, the radar echoes will experience a time-varying doppler shift. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas.  REFLECTOR ANTENNAS  12.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 reflector architectures from this perspective. 
 The gap across which thedischarge takes place isformed bytwo reentrant cones onthe axis ofsymmetry ofthe approximately cylindrical cavity. The cones add capacity totheresonant circuit and thecavity issmaller forthe same wavelength than itwould bewithout them. Tuning is accomplished bypushing one cone inand out onaflexible diaphragm. 
 For  ocean reporting stations or numerical weather prediction grid points over the ocean,  AREPS automatically calculates an evaporation duct refractive profile and appends  it to the bottom of the upper-air observation for a complete description of the propa - gation environment. AREPS computes and displays a number of EM system performance assessment  tactical decision aids. These are radar probability of detection, ESM vulnerability, LF  to EHF communications, simultaneous radar detection and ESM vulnerability, and  surface-search detection ranges. 
 Target range is represented by a number stored in a digital register, as  shown in Figure 9.17. A coincidence circuit senses when the digital counter reaches the  number in the range register and generates the range gate, as indicated in the block dia - gram shown in Figure 9.18. A range error sensed by the range error detector results in an  error voltage that drives a voltage-controlled variable-frequency oscillator to increase  or decrease the count in the range register, depending on the polarity of the error volt - age. 
 It can be seen that the target information obtained is not complete because of sheltering of the single-view 21. Sensors 2019 ,19, 1701 target. Figure 15c is obtained through the image fusion of two angles of view. 
 25–36,  1989. 123. R. 
 SAMPLE VARIA 
 A. Thompson, Spotlight-Mode  SAR: A Signal-Processing Approach , Boston: Kluwer Academic Publishers, 1996.  7. 
 Schwartz16  © IEEE 1956 ) FIGURE 7.11  Comparison of various detectors in log-normal ( s = 6 dB)  interference ( N = 3; Pfa = 10−6) (after D. C. Schleher19 © IEEE 1975 ) ch07.indd   10 12/17/07   2:13:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http: //creativecommons.org /licenses/by/4.0/). 49. 
 A brute-force technique used to eliminate targets with radial  velocities of less than approximately ±40 knots resulting in a total rejection interval  of 80 knots. To keep this rejection of velocities to no more than 25% of the doppler  space available, the ambiguous velocity must be about 320 knots. This requires  PRFs of 1,400 Hz at L band, 3,300 Hz at S band, and 11,000 at X band (unambiguous   ranges, respectively, 58 nmi, 27 nmi, and 5 nmi). 
 The names simrrltaneous lobing and monopulse are used to describe those tracking techniques  which derive angle-error information on the basis of a single pulse.  An example of a simultaneous-lobing technique is amplittrde-comparison mot~op~rlse, or  more simply, monopulse. In this technique the RF signals received from two offset antenna  beams are combined so that both the sum and the difference signals are obtained simulta-  neously. 
 END LOSSES %ACH RADIATING ELEMENT IS USUA LLY DESIGNED TO BE VERY  BROADBAND AND IS DRIVEN BY A 42 CHANNEL IN A TYPICAL !%3! ARRAY 4HERE ARE TYPI 
 NRLReport7533,NavalResearch Laboratory, Washington, D.C.,Mar.27,1973. .31.Andrews. G.A..Jr.:Optimization orRadarDoppler FilterstoMaximize Moving TargetDetection, NAECVN '74Record. 
 It is only an average value  and should not be used for other than general computational purposes. The correct value of k  depends upon meteorological conditions. Bean15·16 found that the average value of k  measured at an altitude of l km varies from 1.25 to 1.45 over the continental United States  during the month of February and from 1.25 to 1.90 during August. 
 TION v 'EOPHYSICS  VOL   PP n     2 * +EELER AND , * 'RIFFITHS  h!COUSTIC DOPPLER EXTRACTION BY ADAPTIVE LINEAR PREDICTION FILTER 
 46, pp. 801–812,  1 July 1992. 110. 
 E., K. M. Siegel. 
 18. Rt~ze, J.: Lateral Feed Displacement in a Paraboloid, IEEE Trans., vol. AP-13. 
 W.: A New Model for Sea Clutter, IEEE Trans., vol. AP-16, pp. 217-223, March, 1968. 
 Aero11a11t. Electro11ics (Dayton, Ohio), pp. 683-687, 1959. 
 The range-sweep voltage isapplied toone pair ofdeflecting plates and the signal and range-mark voltages tothe other. The square wa~-e controlling the cathode-ray-tube intensity is applied tothecathode inproper polarity tobrighten thetube during the range sweep. IntheB-scope display, therange sweep isapplied toadeflection plate just asbefore. 
 The reference waveform applied to the LO port is  x tt Tf t tRR RR R R ( ) cos[ ( ) ( =−   − + 2 2 rectτπ τ πα − −τR) ]2 (8.26) where TR is the pulsewidth, fR is the carrier frequency, tR is the reference waveform  time delay, and aR is the LFM slope for the reference waveform ( aR ≤ a). FIGURE   8. 29 Correlation mixer signals in stretch pulse compression ( after Roth et al.61)Signals at CM Output Time0fIFfRf0FrequencySignals at CM Input 1 12 23 3B T TRtd BRReference Waveform δf = −(B/T)td ch08.indd   32 12/20/07   12:50:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 44.Herger,F.R.:TheDesignofAirborneDoppler Velocity Measuring Systems. IRETrans.•vol.ANE-4. pr.157·175.December. 
 29. Eon, L. G.: An Investigation of the Techniques Designed to Provide Early Warning Radar Fence for the Air Defense of Canada, Defense Research Board (Canada), Rept. 
 Phys., vol. 26, pp. 297-305, March 1955. 
 In a  planar array, the current at a particular element might be influenced significantly by a rela-  tively large number of its neighbors (perhaps from 20 to 100). Since the phases and amplitudes  of the currents at each of the elements change with the scan angle, the effects of mutual  coupling also change with scan angle and complicate the problem of computing and compen-  sating coupling effects. Mutual coupling, therefore, causes the actual radiation pattern to differ  from that which would be predicted from an array of independent radiators. 
 GROUND ECHO  16.596x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 64. J. V . 
 % WAS ALSO A HIGH 
 The high voltage pulses to drive the magnetron were generated in the modulator. The IF ampli ﬁer, detector and mixers for combining radar signals with the range and height markers were contained in the receiver. A physical connection diagram [ 4] is shown in ﬁgure 3.3, which also shows the various switch units and the power supply. 
 TIME PROCESSING IS A POSSIBILITY L -ORE SOPHISTICATED EXPENSIVE  HARDWARE IS REQUIRED TWO ANTENNAS  TWO RECEIVER  CHANNELS  AND TWO SETS OF ANALOG 
 BROADBAND 
 (A further description  as to why the log-FTC receiver is CFAR when the input is Rayleigh clutter is given in  Sec. 13.8.)  RADAR CLUTTER 487 Figure13.7Comparison ofvarious detectors in(a)log-normal clutter withamean-to-median ratioof1 dB, (J=0.693and(b)Weibull clutterwithIX=1.2inEq.(13.12). Probability offalsealarm::::: 10-6, 10hitsintegrated. 
   .OVEMBER   2 3 2AVEN  h2EQUIREMENTS FOR MASTER OSCILLATORS FOR COHERENT RADAR v IN  0ROCEEDINGS OF THE )%%%    VOL   &EBRUARY   PP n AND REPRINTED IN $ + "ARTON   #7 AND $OPPLER 2ADARS   3ECTION 6 
 15.8 MTI system response for 1300-MHz radar operating at 400 pps.TARGET RADIAL VELOCITY (knots)RESPONSE RELATIVE TO NORMAL RECEIVER DOPPLER FREQUENCY (Hz) . doppler frequency. The doppler frequency of the target can be calculated from WRfd = — (15.3) where fd is the doppler frequency, in hertz; VR is the target radial velocity, in meters per second; and X is the transmitted wavelength, in meters. 
   *ANUARY   * ' :ORNIG ET AL  h"ISTATIC SURFACE SCATTERING STRENGTH AT SHORT WAVELENGTHS v 9ALE 5NIVERSITY   $EPT %NG !PPL 3CI 2EPT #3 
 Shipborne Antenna Stabilization.—In recent practice the stabilization ofairborne ground-mapping antennas isbythe line-of-sight method, in. SEC. 9.17] STABILIZATION OF THE BEAM 309 which theseamer hastwo degrees offreedom, correspondhg tothetrain (azimuth) and elevation axes. 
 As can be seen, the target was well focused with low azimuth sidelobes. The azimuth proﬁle obtained using the proposed method was compared with the(N+1)th 2D azimuth proﬁle obtained by a classical 2D focusing algorithm, using a rectangular window (Figure 5c) and a Taylor window with parameters 0.25 (Figure 5d). The proposed method is seen to suppress azimuth sidelobes without degrading the azimuth resolution. 
 BAND RETURNS AND SURFACE SPECTRUM SIMULTANEOUSLY  IN A WAVE TANK AND FOUND "RAGG 
 Receiver Filtering. Subsequent stages of the radar receiver have responses which are functions of the doppler modulation frequency; so the output residue spectrum can be obtained by adding the decibel responses of these filters to the preceding spectrum at the mixer. The receiver contains two cascaded filters: an optimum-bandwidth filter at IF and a doppler filter, generally implemented digitally in modern radars. 
 RADAR CLUTTER 489  clutter. Other means for attenuating long pulses from distributed clutter, yet pass the echoes  from point targets, include the high-pass filter and various forms or pulse-width discriminators  that inhibit echo signals not of the correct pulse width.  13.5 LAND CLUlTER  The clutter from land is generally more of a problem than the clutter from sea. 
 The problem  in combining the outputs of N ports into one port, or vice versa, is to do so with minimum loss.  It is not always appreciated that loss in the array feed is equivalent to a loss in antenna power  gam.  There are at least three basic'concepts for feeding an array. 
 About 50 mw isavailable from reflex klystrons inthe 10-cm region, which is20db. 418 R-F COMPONENTS [SEC. 11.9 above the0.5mw needed toproduce thestandard 0.5maofcrystal cur- rent. 
 There are two outer skins, a center skin, and two intermediate cores. It is used when the  ordinary A sandwich does not provide sufficient strength.  When extreme structural rigidity or broad band capabilities are required with relatively  light weight, multiple-layer sandwiches of seven, nine, eleven, or more layers may be con-  sidered. 
 37. Sollenberger. T. 
 REFLECTS ENERGY TOWARD THE TRANSMITTER  AND THE RECEIVER IS POSITIONED OUTSIDE THE RETRO 
 Sharp, E. D.: A Triangular Arrangement of Planar-Array Elements that Reduces the Number  Needed, IRE Trans., vol. AP-9, pp. 
 The array antenna has the following desirable characteristics not generally enjoyed by  other antenna types:  I~terrialrss, rupitl hearrt-steerirtg. The beam from an array can be scanned, or switched from one  position to another, in a time limited only by the switching speed of the phase shifters.  Typically, the beam can be switched in several microseconds, but it can be considerably  shorter if desired. 
 POLARIZED CASES  &)'52%     3ELECTION OF POLARIZATION SIGNATURES FROM 3!2 IMAGE OF  3AN &RANCISCO A  AN OCEAN AREA  B  A LARGE PARK  AND C  ONE OF SEVERAL  URBAN AREAS AFTER $ , %VANS Ú )%%%         "' *# ' "$! '         ! !() # *$&%# '"-!   
 Vivekanandan, D. S. Zrnic, S. 
 The probability of detection is given by the same expression, with the probability density function that of the signal-noise combination (usually called signal-plus-noise, but the 4'addition" is not necessarily linear): OC Pd = J Psn(v)dv (2.19) The signal-plus-noise probability density function psn(v) depends on the signal- to-noise ratio as well as on the signal and noise statistics. Also, both pn and psn are functions of the rectification law of the receiver detector and of any postdetection processing or circuit nonlinearities. Primarily, however, psn and therefore the probability of detection are functions of the signal-to*noise ratio. 
 Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation.  THE PROPAGATION FACTOR, FP, IN THE RADAR EQUATION  26.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 The standard atmosphere is based primarily on the assumption of a linear decrease  in temperature with height up to the tropopause and an isothermal layer above. In addi - tion, certain other assumptions are (a) The air is dry. 
 8/ 
 M.: The Radio Proximity Fuse, Elec. Eng., vol. 66, pp. 
 375-382. 25. Jao, J. 
 (with respect to the cathode) at the end of the RF pulse to collect the electrons passing through the drift region and thereby make the tube turn off even though high voltage is still applied.22 Turnoff control electrodes in CFAs thus make possible dc operation, which eliminates the high-power modulator. In dc operation, the high voltage is con- tinuously present between anode and cathode, and the current is turned on by applying RF drive and turned off by pulsing the control electrode. To prevent the tube from starting without RF drive, the cathode must be kept cool enough to prevent thermionic emission. 
 122] ATYPICAL RECEIVING SYSTEM 439 before. The latter must beprovided with adelayed trigger which may come from acontinuously variable timing circuit ormay beone pulse ofa discrete set, often therange-marker pulses themselves. The continuous type ofdelay isfrequently associated with acontinuous precision range marker (Sec. 
 In principle, the value of 0'0, the sea backscatter per unit area, is  imkpcndcnt of the illuminated area. In practice, the area illuminated by the radar does affect  the nature of the backscatter. This is especially so with short-pulse radars. 
 The resemblance ofthe PPI display ofamodern microwave radar settoa chart isstriking, and suggested very early that navigation would be assisted byadevice that enabled amap ofthe proper scale tobesuper- 1The problem ofdevising anorganization forusing radar information innaviga- tionisdiscussed inVol.2oftheSeries.. SEC.72] AIDS TO INDIVIDUAL NAVIGATION 215 posed ontheradar indicator. Figure 7.1isaschematic diagram ofone method ofaccomplishing this. 
 SANDWICH WILL NOT PROVIDE SUFFICIENT STRENGTH  OR FOR CERTAIN ELECTRICAL PERFORMANCE CHARACTERISTICS  OR WHEN ONE LAYER IS TO SERVE AS A WARM 
 175. CONTENTS... Xlll RXAMPLES OFTHE MAJOR OPERATIONAL REOUIEEMENTS 175 69 Early Aircraft Warning Radar 175 6.10 PPI Radar forSearch, Control, and Pilotage 182 6.11 Height%nding Involving Ground Reflection. 
 PULSE COMPRESSION RADAR  8.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 The range window width is   ∆rcTB BcB B Tp p= =2 2 ( / ) (8.37) Stretch Pulse Compression Radar Examples.  This section describes three  examples of radars that employ stretch pulse compression systems.  Long Range Imaging Radar.62,63 The Long Range Imaging Radar (LRIR) is an  X-band radar with stretch processing bandwidths of 0.8, 1.6 MHz, and 3.2 MHz. 
 Richard Lodwig, private communication, Lockheed Martin Mission Systems, 2003. 127. H. 
 When the errors are correlated, the sidelobe energy will be  lumped at discrete locations in the far field. The correlated errors will, therefore, pro - vide higher sidelobes, but only at a limited number of locations. Both correlated and  random sidelobes are of concern to antenna designers. 
 ARRAY !DAPTIVITY  4APERING AT THE ARRAY ELEMENT LEVEL  PRODUCES UNEQUAL NOISE POWER AT SUB 
 The tower top appears in the image 5 m closer to the radar  than the tower base. This principle may sometimes be used to estimate the height of  isolated, tower-like structures on relatively level ground:  hdR Hg≅cosθsq (17.52) The intersection of the constant-velocity cone and the ground is a hyperbola. If  H is not  R, the isodop direction will not be parallel to the down-range direction. 
 Compounding the eclipsing problem is interference from range sidelobes when pulse compression is used by the transmitter. If linear FM pulse compres- sion is used, Hamming or cosine-squared time-domain weighting by the receiver improves ncar-in sidclobe suppression by about 5 dB, when compared with the same type of frequency-domain weighting.79 For a hyperbolic location system, target location errors decrease as the target approaches the line joining the two transmitters. For a theta-theta location sys- tem, the error is a minimum when the target lies on the perpendicular bisector of the baseline with (3 = 45° and increases elsewhere.18 When successive data mea- surements (or redundant data) arc available to a bistatic or multistatic radar, tar- get state estimates can be made with Kalman or other types of filters.80'81 Coverage. 
 Jasik. f 1.: 7'he l:lcct~~o~naprictic '1'licot.y of tlie Luriebttrg Lens, AFCRC Repr. TR-54-121, Novetnhcr,  1954. 
 (Tracking radars are normally operated with range gates.) The boxcar generator  consists of an electric circuit that clamps the potential of a storage element, such as a capacitor,  to the video-pulse amplitude each time the pulse is received. The capacitor maintains the  po ten ti al of the pulse during the en tire repetition period and is altered only when a new video  pulse appears whose amplitude differs from the previous one. The boxcar generator eliminates  the pulse repetition frequency and reduces its harmonics. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.6  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 These parameters are explained briefly as follows: Antennas, Gt and Gr : A common convention for HF-band radars is to include the  effect of the ground in the antenna performance characterization, and that con - vention will be used here. For example, a half-wave dipole in free space has a  maximum gain over an isotrope of 2.15 dB. 
   PP n  *ULY   # 2OTHENBERG AND , 3CHWARTZMAN  h0HASED ARRAY SIGNAL BANDWIDTH v ).  )%%% )NT 3YMP  !NTENNAS 0ROPAG $IG  $ECEMBER   PP n  7 2OTMAN AND 2 & 4URNER  h7IDE ANGLE LENS FOR LINE SOURCE APPLICATIONS v  )%%% 4RANS    VOL !0 
 DETECTION OF RADAR SIGNALS IN NOISE 393  .- Tnpp~d delay line Test Tapped delay line  1 Greater  0 f  I WAF? Threshold output  Fi~ure 10.1 1 Cell averaging CFAR. In this version the greater of the outputs from the range cells ahead of  or behind the cell of interest is used to set the threshold.  oss with a conventional cell-averaging CFAR is 0.8 dB. 
 viewed, therefore, as a single complex zero-mean gaussian random variable.* The rmse associated with the accuracy performance of a particular radar angle measurement technique, as limited solely by the presence of thermal noise on the technique, is termed herein the fundamental accuracy of the technique. The fundamental accuracy of two general categories of elevation-angle esti- mation techniques is presented in this section: the sequential-lobing technique and the simultaneous-lobing technique. Other practical effects influencing the height accuracy of a radar system include: beam-pointing errors, pattern errors, channel mismatch errors, calibration, platform orientation and gyration, stabili- zation, compensation, ECM-ECCM and clutter errors, multipath, target fluctua- tions and thresholding effects, and multiple hit and channel combining. 
 ORBIT VELOCITY AND HENCE PERIOD   ORBIT INCLINATION  AND THE ROTATION RATE OF THE PLANET %ARTH 
 Thereflection coefficient ofthesurfacemaybeconsidered asacomplex quantityr=peN.Therealpartpdescribes the changeinamplitude, whiletheargument'" describes thephaseshiftonreflection. Itisfurtherassumed inthepresentexample thatthereflection coefficientr= -1.The reflected wavesuffersnochangeinamplitude, butitsphaseisshifted180°.Areflection coefficient of- 1appliesatmicrowave frequencies toasmooth surfacewithgoodreflecting properties iftheradiation ishorizontally polarized andtheangleofincidence issmall. Theeffective radiation patternoftheradarlocatedatAinFig.12.1maybefoundina manner analogous tothatofatwo-element interferometer antenna formedbytheradar antenna atAanditsimagemirrored bythegroundatA'.Thedifference between thereflected pathAMBandthedirectpathAB(orA"MB)isi\=2hasin~,whenR~ha•For~small,sin~ maybereplaced by(ha+h,)1Rsotha~'i\=2ha(ha+h,)1R::::::2hah,IR.Thelatterexpression 8~Target _~.-- ~D?!ir~e~ct~wo~v~e --:-:::::::;::::::1 Radar R Figure12.1Propagation overaplanereflecting surface.. 
 This estimator is widely used for mean-frequency estimation with doppler me- teorological radars. The estimates are unbiased in the presence of noise when the doppler spectrum is symmetrical. Its greatest appeal, however, is due to its com- putational simplicity. 
    
 In a jamming environment, it can lull the radar operator into a false sense of  security since the ideal CF AR, by maintaining the output noise level constant no matll!r what  the level of the input noise, provides no indication that jamming is present. Additional means  must be incorporated into a CF AR to provide the operator with warning of the presence of . noise Jamming. 
 The magnetron is a crossed-field device in that the electric field is perpendicular to a static  magnetic field. Although the name magnetron has been applied in the past to several different  electron devices,3 it was the application of cavity resonators to the magnetron structure that  permitted a workable microwave oscillator of high power and high efficiency.  Conventional magnetron. 
 40.Jackson, J.,andE.Goodall: A360°Scanning Microwave Reflector, Marconi Rel'.,vol.21.istqtr., pp.30-38,1958. 41.Barab,J.D.,J.G.Marangoni, andW.G.Scott:TheParabolic DomeAntenna: ALargeAperture, 360Degree, RapidScanAntenna, IREWESCON Conv.Record,vol.2,pt.I,pp.272-293, 195H. 42.Jasik.H.:"Antenna Engineering Handbook," McGraw-Hili BookCo.,NewYork,1961,sec.15.6. 
 The ]Rise time isconveniently defined asthetime required fortheoutput voltage of theamplifier tmr&efrom 10percent to90percent ofitsfinal value when asquare pulse isapplied totheinput,. SEC. 12.6] VIDEO AMPLIFIERS 451 amplifier must recover from large signals quickly, requiring that nocontrol-grid current bedrawn onstrong signals. 
 For example, with  gaussian noise, a crest factor of 4 sets the peak level at the 4 s level (12 dB above  the rms level) with a probability of 0.999937 that the full-scale is not exceeded on  each A/D converter sample. Setting the system noise level power spectral density into the A/D converter R(dB)  above the A/D converter noise gives  R dBf N B Ns( ) log =   10210SYS IF ADC (6.45) where  NSYS = system noise at A/D converter input in bandwidth BIF Combining Eq. 6.43 and 6.44 gives the required SNR as  SNR d BP C B f NR dBI SADCIF SYS( ) log ( =  + 102 102 ) ) (6.46) The generation of baseband I and Q signals from the IF sampled A/D converter data  is performed using digital signal processing and can be implemented through a variety  of approaches.7 Two approaches are described next. 
 The upper half of the reflector is  a parabola and reflects energy from the feed in a direction parallel to the axis, as in any other  parabolic antenna. The lower half, however, is distorted from the parabolic contour so as to  direct a portion of the energy in the upward direction.  A cosecant-squared antenna pattern can also be produced by feeding the parabolic  reflector with two or more horns or with a linear array. 
 SHAPED SHADED AREAS CORRESPOND TO A CERTAIN RADAR PROBABILITY OF DETECTION OF VARIOUS TARGETS BY VARIOUS OPERATIONAL RADARS &OR EXAMPLE  THE SMALL FAN 
 Fiandrotti, A.; Fosson, S.; Ravazzi, C.; Magli, E. PISTA: Parallel Iterative Soft Thresholding Algorithmfor Sparse Image Recovery. In Proceedings of the Picture Coding Symposium (PCS), San Jose, CA, USA, 8–11 December 2013; pp. 
 Ê 
 H. Stewart, “Studies of the sea using HF radio scatter,” IEEE   J. Oceanic Eng ., vol. 
 One common  construction of a TR consists or a section of waveguide containing one or more resonant filters . 362 INTRODUCTION TO RADAR SYSTEMS  Transmitter  Dummy load  Transmitter ATR tubes  (tired) ~ H\!Ct:i\ll!l ----'-'·'--""----~~---~----- protector  3 >( __ ~_x ___ _  Short-slot )..q Short-slot  hybrid f-2-.J hybrid Antenna  ( al  ATR tubes  ______ C-::'\ ~ Receiver ~<~~~----- protector  Dummy load ~,_ ___ X ___ E.3-E3 c;:::::_~------- Antenna  Short-slot S hart-slot  hybrid hybrid  ( b) .J  Figure 9.7 Balanced duplexer using ATR tubes. (a) Transmit condition; (b) receive condition. 
 Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar.  PULSE DOPPLER RADAR  4.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 To reduce doppler filter sidelobes, a 90 dB Dolph-Chebyshev weighting is applied,  which reduces the coherent integration SNR gain by about 2.66 dB. For detection,  three CPIs are integrated noncoherently via PDI for an approximate integration gain   in dB of 10 log10(NPDI0.8), or 3.82 dB. 
  
 B. Van Brunt, Applied ECM , vol. 2, Dunn Loring, V A: EW Engineering, Inc., 1982. 
  AND 7 
 99. Sheleg, B.: Butler Submatrix Feed Systems for Antenna Arrays, IEEE Trans., vol. AP-21, pp. 
 PRISES NOT ONLY THE SELF NOISE GENERATED IN THE RADAR RECEIVER BUT ALSO THE ENERGY RECEIVED FROM GALACTIC SOURCES  NEIGHBORING RADARS AND COMMUNICATION EQUIPMENT  AND POSSIBLY JAMMERS 4HE PORTION OF THE RADARS OWN RADIATED ENERGY THAT IS SCATTERED BY UNDESIRED TARGETS SUCH AS RAIN  SNOW  BIRDS  INSECTS  ATMOSPHERIC PERTURBATIONS  AND CHAFF  MAY ALSO BE CLASSIFIED AS INTERFERENCE AND IS COMMONLY CATEGORIZED AS CLUTTER 7HERE AIR 
 TABLE 5.2 System Applications for Microwave Power Transistors* *Reprinted with permission from E. D. Ostroff et al., "Solid-State Transmitters," Artech House, Norwood, Mass., 1985. 
 LENGTHS AND 6(&   TYPICAL SENSITIVITIES ARE  OF THE ORDER OF  T O  D" ABOVE FREE SPACE  INSTEAD OF THE IDEAL  D" 7HEN THE RANGE TO THE TARGET IS RELATIVELY SHORT AND TESTS MUST BE PERFORMED OVER  A WIDE RANGE OF FREQUENCIES  IT IS SOMETIMES ADVANTAGEOUS TO ATTEMPT TO DEFEAT THE GROUND 
 FIG. 10.12 Digital pulse compression for phase-coded signals. generate the biphase-modulated transmitted signal. 
 P. Kollias, B. A. 
 In general, complicated motion of a tar - get during a SAR data collection prevents formation of a clear SAR image of the target. Detection of Moving Targets in SAR Images.  Various processing methods have  been developed to detect and reposition moving targets: Single-Aperture Moving-Target Indication (MTI) SAR  With respect to con - ventional  single-aperture SAR, key results have been obtained by several authors,  including Raney,38 Freeman,39 Freeman and Currie,40 and Werness et al.41 If the  PRF is greater than the minimum necessary to produce a SAR image, then further  doppler bands are available. 
 The corresponding time  waveform consists of two sine waves at frequencies /0 ± 8/2. This is the two-frequency CW  radar waveform discussed in Sec. 3.5. 
 Since loss of the focusing  magnetic field could cause the tube to fail, protective circuitry is normally employed to remove  the beam voltage in the event or improper focusing or the complete loss of focusing. The  collector of most high-power klystrons is insulated from the body (RF interaction circuit) of  the tube so as to allow separate metering and overload protection for the body current and the  collector current.  Pulse modulation. 
 This  tube delivers a peak power of 250 kW with a  0.00 I duty cycle over the frequency range from  5.45 to 5.825 GHz. The efficiency is 40 to 45  percent. (Courtesy V aria11 Associates, Inc .. 
 For example, it can be used as a means of targd  classification or recognition, as a precision vector miss-distance indicator for uninstrument.ed  targets, as a counter (ECCM) to repeater jammers, as an aid in low-angle tracking, and as a  means for discriminating unwanted clutter or chaff from the desired target.  ..  Tracking in doppler. 
 They respond to the slow variations in the feedthrough signal without damage to the dopplers. For complete details of the mechanical design, see Ref. 8. 
 A radial velocity difference of 25 m/s over the length of a jet runway (^l km) is of serious concern. One principal problem concerning microbursts is their short lifetimes, which are of order 15 min. The duration of peak intensity is only 1 or 2 min. 
 BANDWIDTH PRODUCTn  4HE PRESENCE OF CLUTTER THAT  IF NOT PROPERLY REMOVED  MAY CAPTURE THE ADAPTIVE SYS 
 TION 4HUS  WHEREAS MANY NON 
 This is  the first of two thresholds, hence the name double-threshold detector which is sometimes used.  The output of the first threshold is sampled by the quantizer at least once per range-resolution  cell. A standard pulse is generated if the video waveform exceeds the first threshold, and  nothing if it does not. 
 TIME CHARACTERIZATION AND ADAPTIVE PROCESSING OF IONOSPHERICALLY 
 PULSE  FILTER &OR FEEDBACK ))2  FILTERS  IT IS INAPPROPRIATE TO CALL THEM TWO 
 ING RADAR   AS THE TRANSMITTER FOR A NEW RADAR DESIGN AND   AS AN ACTIVE APERTURE PHASED ARRAY RADAR !N EXAMPLE OF REPLACING AN EXISTING VACUUM TUBE TRANSMITTER WITH A SOLID 
 Shreve7 has derived a formula for the double-sideband noise power. He took the boundary of the Fresnel region RF = D2IX as the lower limit of the integral. NOISE IN RECEIVER/NOISE IN TRANSMITTER (dB) . 
 Adjustments to parameters of gtrack  can be made to obtain the desired noise and lag tradeoff. Selection of Tracking Coordinates.  The Kalman filter assumes linear target  motion and a linear relation between the radar detections and the target coordinates. 
 (after D. J. Salmond70 © SPIE 1990 ) ch07.indd   41 12/17/07   2:14:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 29.Luck.D.G.c.:"Frequency Modulated Radar." McGraw-Hili BookCompany. NewYork.1949. 30.Wimberley. 
 A short-pulse radar can negate the operation of certain electronic countermeasures  such as range-gate stealers and repeater jammers, if the response time of the ECM is  greater than the radar pulse duration. The wide bandwidth of the short-pulse radar also  has some advantage against noise jammers.  Doppler tolerartce. 
 Upton, L. 0, and G. J. 
 TheeITectofk<Iisthattheintegrator hasimperfect" memory." The optimum valueofkdepends onthenumberofpulsesreceived fromthetarget(Sec.2.6and Ref.65). Analogdelaylinesthathavebeenusedinsuchdevicesincludeacoustic lines.lumped­ parameter delaylines,electrostatic storage tubes,andmagnetic drumsordisks~Theydonot have,ingeneral, sufficient stability topermitlargevaluesofk.Whenanaloglinesareused, loopgainsarenotmuchlargerthan0.9intheconfiguration ofFig.10.lOa,and0.98inthe configuration ofFig.10.lOb.Sincetheeffective number ofpulsesintegrated isequalto (I-krI,avalueofk=0.9corresponds toabout10pulsesintegrated andk=0.98toabout 50pulses.However, whentherecirculating-delay-line integrator isimplemented withdigital circuitry, valuesofkapproaching unitycanbeachieved.6s• Thefactorkintherecirculating-delay-line integrator ofFig.1O.lOaisequivalent toan exponential weighting ofthereceived pulses.Itresultsinalossofabout1.0dBinsignal-to­ noiseratioascompared withtheidealpostdetection integrator thatweightsthereceived pulses indirectproportion tothefourthpoweroftheantenna beampattern.66Itis0.5dBJess efficientthanthemovingwindowdetector withuniform weights.67Thedouble-loop integrator ofFig.to.lObisatwo-pole filterwithamultiple pole.Itisabout0.3dBlessefficient thanthe idealintegrator withoptimum weights.66Thedoubledelay-line configuration ofFig.1O.Wcis alsoatwo-pole filterbutunlikethedouble-loop integrator, thetwopolesneednotbeatthe samelocation. Itsdetection performance isonly0.15dBlessefficient thantheoptimum.66 Therecirculating delay-line integrators ofFig.10.10canbeusedtoobtainanestimateof. 
 The cross section for back scattering from ametal spherel divided by~azisplotted vs.a/X inFig. IP.J.Rubenstein, RLReport So.42,.\pr. 3,1943, \-umerical values forthe problem ofscattering from adielectric sphere canbefound forcertain values ofthe dielectric constant inthereferences given byStratton, Electromagnetic Theory, McGraw-Hill, New York, 1941, p.563ff.SeealsoRobert JVeinstock, RRL Report. 
 ONLY CONTROL  &)'52%    !RRAY CONFIGURATIONS FOR PERFORM 
 W. P., and T. T. 
 AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 residuals generally indicate a maneuver (a deviation from the filter model). Upon  maneuver detection, the maneuver spectral density, q, is increased in the Kalman filter  model, resulting in higher tracking gains and better following of the maneuver . A more complex approach is to use multiple Kalman filters running simultaneously  with different target motion models—generally, different q values or different equa - tions for target motion (e.g., constant acceleration or constant velocity). 
 NOISE RATIO BETWEEN THE INPUT AND THE OUTPUT OF THE FILTER DUE TO THE COHERENT SUMMATION OF INDIVIDUAL TARGET RETURNS !GAIN THESE COHERENT GAIN VALUES WOULD USUALLY DIFFER FROM FILTER TO FILTER DUE TO POTENTIALLY DIFFERENT DOPPLER FILTER CHARACTERISTICS 4HESE COHERENT GAIN VALUES WILL INCLUDE THE FILTER MISMATCH LOSS BUT NOT THE STRADDLING LOSSES BETWEEN ADJACENT FILTERS 4HE PRODUCT OF THE CLUTTER ATTENUATION   #! I  AND THE COHERENT GAIN   '#MAX I  FOR THE ITH DOPPLER FILTER BECOMES THE DEFINITION OF THE SIGNAL 
 Kropfli, and W. R. Moninger: A Millimeter- Wavelength Dual-Polarization Doppler Radar for Cloud and Precipitation Studies, J. 
 Because ofthis bias, nosignal passes through the diode until the sawtooth has reached adefinite amplitude, determined bythe bias value. When the critical amplitude isreached (attime tlonthewaveform diagram), the remainder ofthe sawtooth appears onthe grid ofVG. This partial sawtooth isamplified byVc, differentiated inthe plate-loading trans- former, further amplified inVT,and ultimately used totrigger, thesingle- stroke blocking oscillator circuit ofVa,which produces thedelayed pulse. 
 Tomlinson: C.C.D. Chebyshev Filter for Radar MTI Applications, Elec­ cmnics Lepers, vol. 10, no. 
 STATE 42 MODULES  DISTRIBUTED ON FOUR PANELS WHOSE DEPLOYED DIMENSIONS ARE  M BY  M  VERTICAL AND HORIZONTAL  RESPECTIVELY 3PACECRAFT VELOCITY AND ANTENNA LENGTH DICTATE A LOWER BOUND ON PULSE REPETITION FREQUENCY  WHICH FOR 0!,3!2 SPANS  K(Zn K(Z  DEPENDING ON MODE 0EAK TRANSMITTED POWER IS  ^ K7  TWICE THAT OF THE 3EASAT 3!2  4HE RESULTING SENSITIVITY NOISE 
  2EC  4OKYO  /CTOBER n    * 0 (ANSEN  h! SYSTEM FOR PERFORMING ULTRA HIGH RESOLUTION BACKSCATTER MEASUREMENTS OF  SPLASHES v IN 0ROC )NT -ICROWAVE 4HEORY  4ECHNIQUES 3YMP   "ALTIMORE    , " 7ETZEL  h/N THE THEORY OF ELECTROMAGNETIC SCATTERING FROM A RAINDROP SPLASH v  2ADIO 3CI   VOL   .O   PP n    2 2OMEISER  ! 3CHMIDT  AND 7 !LPERS  h! THREE 
 Stability is the inverse of this ratio; both are  generally expressed in decibels. ch06.indd   20 12/17/07   2:03:20 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Ashrewd observer would call “Signal” whenever thescope deflection atthis point was only alittle greater than average, and could score apretty good “batting average” even for rather weak signals. If,however, he expected thesignal tooccur only very rarely, hewould naturally sethis standard higher, inorder toavoid frequent false identification ofwhat were, infact, noise fluctuations. For obvious reasons, nosuch clear delineation ofthestatistical prob- lem ispossible inthenormal operation ofaradar set. 
 W. Shrader: MTI Performance Caused by Limiting, EASCON '68 Record,  Supplement to IEEE Trans, vol. AES-4, pp. 
 A bank of dispersive filters are needed to cover the angular  sector, as described in Sec. 8.4. Each filter would be designed to accommodate the spread of  frequencies expected from a particular elevation angle. 
 ING EFFECTS HAVE BEEN NEGLECTED  AT A CONSTANT VELOCITY  IN A DIRECTION OBLIQUE WITH RESPECT TO THE RADAR MOTION 4HE VELOCITY PARAMETERS HAVE BEEN CHOSEN IN ORDER TO MAKE EVIDENT THE PRESENCE OF RANGE MIGRATION AND OF CROSS 
 Conclusions In this paper SPARX system have been introduced and described. It is a new MIMO system developed by IDS GeoRadar, in order to overcome some limitations of the current GB-InSAR systems. In particular, by decomposing the system into independent modules and using integrated technologies such as patch antennas and microstrip transmission line, SPARX development aims to reduce production costs and facilitate installation procedures compared to the current GB-InSAR MIMO 127. 
 Moreover, owing toashortage oftrained men and tothe difficulties involved inmaintaining equipment ofthis kind inwartime, the antenna systems were often badly installed and inadequately main- tained. Inconsequence, large errors inapparent azimuth were very common; most stations had errors of10°or15°, and errors aslarge as30° were not unknown. The method ofmeasuring height depended on reflection ofthe received waves from the ground, and almost invariably theheight calibration ofastation was different along different azimuths. 
 TRACKING ERRORS CAUSE SIGNIFICANT ERRORS IN CALCULATED TARGET ANGLE BASED ON THE RANGE MEASUREMENTS 4HESE ERRORS MUST BE FULLY UNDERSTOOD TO ASSESS THE PERFORMANCE OF MULTILATERATION SYSTEMS 4ARGET 
 MENTS BY DETECTING THE PRESENCE OF A NONUNIFORM WIND FLOW #ARBONE  3TRAUCH  AND (EYMSFIELD  AND 3TRAUCH ET AL ADDRESS THE ISSUE OF WIND MEASUREMENT ERROR  IN DETAIL 4HE READER IS REFERRED TO THE REVIEW PAPER BY 2TTGER AND ,ARSEN FOR A  THOROUGH TREATMENT OF WIND 
 NOISE RATIO IN RANGE 
 BEAM SHORT 
 TION TIME  4!Z MAY BE REDUCED BELOW THE CANONICAL LIMIT SET BY THE AZIMUTH ANTENNA  BEAMWIDTH 4HIS IS ACCOMPLISHED BY TURNING OFF THE TRANSMITTER AFTER ENOUGH PULSES HAVE BEEN COLLECTED TO SATISFY THE AZIMUTH RESOLUTION REQUIREMENT %ACH SUCH BURST HAS AN INSTANTANEOUS DOPPLER CORRESPONDING TO THE ANTENNA BEAMWIDTH WHICH DETERMINES THE .YQUIST 02& LIMIT   BUT A SHORTER SYNTHETIC APERTURE LENGTH "URST MODE IS STANDARD . £n°Ó{  2!$!2 (!.$"//+  OPERATING PROCEDURE FOR PLANETARY OR LUNAR RADARS  FOR WHICH HIGH IMAGE RESOLUTION IS  NOT REQUIRED AND THE SPACECRAFT 
 The exact relationship between peak cathode emission and pulse length depends onthe type, temperature, and age ofthe cathode. Toafair degree of approximation, the maxi mum permissible peak emission varies inversely asthe square root ofthe pulse length: 1-= =l/~. Thus acathode which will emit 20amp forapulse duration of2psec will probably emit 40amp during a0.5-psec pulse. 
 THRESHOLD DETEC 
 FORMING #"&  AND II  SPATIALLY ADAPTIVE PROCESSING DESIGNED TO MINIMIZE ENERGY OUT 
 ('otrttrt~rt~ic~afio~~.~ Rrst~c~rclr Ccr~trc~ (Ottawa, Canada, CRC Rcpt. no. 1299. 
 The total frequency scan of this feed will be  ∆∆ ∆q qq0 0 01= ±f ff fgtancosλ λrad ( CW)  Center-Fed Series Feed.85 A center-fed array (Figure 13.25) can be considered  as two end feeds. Each feed controls an aperture that is half the total and, therefore,  has twice the beamwidth. As the frequency is changed, each half of the aperture scans  in the opposite direction. 
 Ê," ÊÊ, , $ETECTION OF TARGETS IS OF LITTLE VALUE UNLESS SOME INFORMATION ABOUT THE TARGET IS OBTAINED AS WELL ,IKEWISE  TARGET INFORMATION WITHOUT TARGET DETECTION IS MEANINGLESS 2ANGE 0ROBABLY THE MOST DISTINGUISHING FEATURE OF A CONVENTIONAL RADAR IS ITS ABILITY  TO DETERMINE THE RANGE TO A TARGET BY MEASURING THE TIME IT TAKES FOR THE RADAR SIGNAL TO PROPAGATE AT THE SPEED OF LIGHT OUT TO THE TARGET AND BACK TO THE RADAR .O OTHER SENSOR CAN MEASURE THE DISTANCE TO A REMOTE TARGET AT LONG RANGE WITH THE ACCURACY OF RADAR BASICALLY LIMITED AT LONG RANGES BY THE ACCURACY OF THE KNOWLEDGE OF THE VELOCITY OF PROPAGATION  !T MODEST RANGES  THE PRECISION CAN BE A FEW CENTIMETERS 4O MEASURE RANGE  SOME SORT OF TIMING MARK MUST BE INTRODUCED ON THE TRANSMITTED WAVEFORM ! TIMING MARK CAN  BE A SHORT PULSE AN AMPLITUDE MODULATION OF THE SIGNAL   BUT IT CAN ALSO BE A DISTINCTIVE MODULATION OF THE FREQUENCY OR PHASE 4HE ACCURACY OF A RANGE MEASUREMENT DEPENDS ON THE RADAR SIGNAL BANDWIDTH THE WIDER THE BANDWIDTH  THE GREATER THE ACCURACY 4HUS BANDWIDTH IS THE BASIC MEASURE OF RANGE ACCURACY 2ADIAL 6ELOCITY  4HE RADIAL VELOCITY OF A TARGET IS OBTAINED FROM THE RATE OF CHANGE  OF RANGE OVER A PERIOD OF TIME )T CAN ALSO BE OBTAINED FROM THE MEASUREMENT OF THE DOP 
 In some situations there might be too much information to be fully inserted  during the available dead time. In a long-range air-traffic-control radar located in a busy area  there might be more than a hundred targets for display extracted. For each target the  necessary information to be presented might consist of perhaps ten alphanumeric characters  and a number of line segments.35 When the amount of data is large, writing time might  have to be taken from the radar time by blanking one out of every n sweeps or writing the  synthetic information during a random interruption of the sweep. 
 DIMENSIONAL RANGE MEASURE 
 27-31,  January. 1959.  48. 
 BASED SYSTEM TO INCORPORATE A QUAD 
 The rectangular frequency function W0(f), that is, uniform weighting over the band, leads to a (sin x)lx time function wQ(t) with high-level sidelobes, which can be objectionable in some cases. A normalized logarithmic plot of the magnitude of this time function is shown by curve A in Fig. 10.15. 
 STATE 4RANSMITTERS 4HE HIGH SATURATED VELOCITY  BREAKDOWN FIELD  AND THERMAL  CONDUCTIVITY OF 3I# AND 'A. MAKE THEM ATTRACTIVE FOR HIGH 
 CARBIDE SOLID 
 Note that at very low altitudes,  the angles that subtend the first range gate on the ground can be quite big, and the  spectral width widens. Sidelobe Clutter.  The entire clutter spectrum can be calculated for each range  gate by Eq. 
 Shrader32  © IEEE 2007 and H. R. Ward and W. 
 E <t  1 2 3 4 5 6 7  O NT NT NT NT NT NT NT  Frequency 1 T Figure 4.23 MTI doppler filter  bank resulting from the processing  of N = 8 pulses with the weights of  Eq. (4.13), yielding the response or  Eq. (4.16). 
 JAMMING SITUATION  THE ADVANTAGE IS WITH THE JAMMER BECAUSE THE RADAR EXPERIENCES A TWO 
 SHAPED CLUTTER SPECTRUM &OR TYPICAL NUMBERS OF PULSES IN THE -4) THREE TO FIVE   THE BINOMIAL COEFFICIENTS ARE REMARKABLY ROBUST AND PROVIDE A PERFORMANCE WHICH IS WITHIN A FEW DECIBELS OF THE OPTIMUM !GAIN  IT SHOULD BE NOTED THAT ANY ATTEMPT TO IMPLEMENT AN -4) CANCELER  WHICH PERFORMS CLOSE TO THE OPTIMUM  WOULD REQUIRE THE USE OF ADAPTIVE TECHNIQUES THAT ESTIMATE THE CLUTTER CHARACTERISTICS IN REAL TIME )F THE  ESTIMATE IS IN ERROR  THE  ACTUAL PERFORMANCE MAY FALL  BELOW THAT OF THE BINOMIAL 
 RIC PARAMETERS ARE THE hDIFFERENTIAL REFLECTIVITYv  : DR  AND hDIFFERENTIAL PHASEv &DP    WHICH GIVE BULK SCATTERING AND PROPAGATION CHARACTERISTICS OF THE METEOROLOGICAL TAR 
 Inhomogeneities of the atmospheric  index of refraction generally do not produce strong enough backscatter to he a serious sotirct. -;  of clutter to most radars.  Birds. 
 This is not available in a lens where the mechanical support is from the  ~~eriphery of the leris arid from the mechanical properties of the lens material itself. Another  source of error in the lens not found in reflector antenna is the variation in the properties of  tlie leris material. Both real arid artificial dielectrics are not always perfectly uniform from  sar~iple to sar~iple or even witliin tlie same sample. 
 Problems have also occurred as a result of adjacent radars injecting enough RF energy into the system antenna and back into the transmitter to turn on a de-operated CFA at the wrong times. The low insertion loss of CFAs from RF input to RF output without modulator voltage applied permits convenient programming of CFA amplifier chain power output in steps.24 For example, in an amplifier chain transmitter with two CFAs preceded by a TWT, three power-output levels can be selected simply by choos- ing which modulators to pulse. Power programming, also called feedthrough op- eration, is especially useful in 3D radar applications, since it permits conserving average power by reducing the peak power output at high scan angles. 
 The expressions in Table 23.1 can also be used to assess first-order bistatic radar  line-of-sight (LOS) constraints, where the LOS is defined as a line between transmit  and receive antennas tangent to the Earth’s surface. Specifically, for a given target,  transmitter and receiver altitudes, the target must simultaneously be within LOS to  both the transmitter and receiver sites. For a smooth, 4/3 Earth model, the LOS range  rR between a receive antenna of altitude hR and target of altitude ht is  rR = 130 ( √hR + √ht) (23.5) where all units are in kilometers. 
 ....1 l.l What Radar Does..... 1 1.2 How Radar Works. 3 1.3 Components ofaRadar System. 
 An antenna not  compensated for the angular motion of the platform will have degraded coverage. On a ship,  for example, an unstabilized antenna with its beam parallel to the deck plane will have its  coverage shortened for surface targets since the beam will be looking into the water or up in  the air as the ship rolls or pitches. In addition to degraded coverage, the measurement of the  angular position with an unstabilized antenna can be in error unless the tilting of the platform  is properly taken into account. 
 Y. Lee, J. D. 
 COMPRESSION WAVEFORMS TO OBTAIN THE RESO 
 FACE ARRAYS  EACH CONTAINING AROUND   TRANSMIT  RECEIVE 42  ELEMENTS SEE &IGURE   4HESE ELEMENTS ARE CONNECTED TO  42 INTEGRATED MULTI 
 mental conditions. These radar parameters might need to be changed according to the local weather, the clutter environment (which is seldom uniform in azimuth and range), interference to or from other electronic equipment, and (if a military radar) the nature of the hostile ECM environment. The different parameters, op- timized for each particular situation, can be programmed into the radar ahead of time in anticipation of the environment, or they can be chosen by an operator in real time according to the observed environmental conditions. 
 Awide variety oflinear potentiometers differing inaccuracy, size, ruggedness, and soonhave been developed specifically forradar use (see Vol. 17).1 For many pur- poses they provide the simplest method ofdata transmission and often they are more effective than any other device. Adifficulty arises, however, inthose cases where itisnecessary toshift the sector under view. 
 If the  frequency is sufficiently low. the cross section of small aircraft or missiles might be smaller  than their microwave values.  It was mentioned that external sources of interference from other HF users can limit the  sensitivity of the HF radar receiver. 
 and K. A. Roche: Moving-Target-Indicator Recursive Radar Filter using  Bucket-Brigade Circuits, Electronics Letters, vol. 
 This loss is a function of range, altitude, and  weather. It is also a two-way loss. Propagation loss is more of a environmental loss  than a system loss, but can be grouped with the other losses that make up net loss in  the radar range equation. 
 38. Peeler, G. D. 
 SUBMERSIBLE PLATFORM SUPPORTING THE 'ROUND 
 TheVA-812C formed thehasisforthedesignoftheVA-842, atubeusedintheBallistic MissileEarlyWarning System(BMEWS), withademonstrated lifeinexcessof50,000hours.TheVA-812E, which wasalsoderivedfromthesamefamilyastheVA-812C, hasapeakpowerof20MWwithan instantaneous I-dBbandwidth of25MHzanda40dBgain.Itsaverage powerratingis 300kWatadutyof0.015anda40JLSpulsewidth.. 6.4 TRAVELING-WAVE-TUBE 'AMPLIFIER  The traveling wave tube (TWT) is another example of a linear-bcanl, or 0-type, tuhc. It dlffcrs  from the klystron amplifier by the continuous interaction of the electron beam and the RF  field over the entire length of the propagating structure of the traveling-wavc tubc rathcr tllarl  the interaction occurring at the gaps of a relatively few resonant cavities. 
 TIME 
 8.5.1  MTI with Delay -Line Canceller   By being given a video signal of a pulse Doppler Radar on a display terminal with sweep (A - Scope) according to Figure 8.8c and then successively re presenting the echoes of the follo w- ing pulses, then one can obtain the curves a -e in Figure 8.8.  If one uses a display terminal  with memory and “writes” the echoes on top of one another, then one obtains Figure 8.8 Σ.   Fixed targets deliver constant echo a mplitudes, while moving targets deliver sine -shaped am- plitudes as in Figure 8.8c. 
 L. Maisel, “Performance of sidelobe blanking systems,” IEEE Transactions on Aerospace and  Electronic Systems,  vol. AES-4, pp. 
 7.24. The upper half of the reflector is  a parabola and reflects energy from the feed in a di.rection parallel to the axis, as in any other  parabolic antenna. The lower half, however, is distorted from the parabolic contour so as to  direct a portion of the energy in the upward direction. 
 PARAMETER MEAN AND VARIANCE  THRESHOLD OR ADAPT A ONE 
 (TSC): private communication, February 1988. 91. Kock, W. 
 These two arrangements are examples of rear  feeds. The waveguide rear feed shown in Fig. 7.9b produces an asymmetrical pattern since the  transmission line is not in the center of the dish. 
 WAVEHEIGHT CONDITION EXPRESSED BY %Q  MEANS THAT AT 8 BAND  FOR EXAMPLE  THE MAXIMUM DEPARTURE OF THE SEA SURFACE FROM A FLAT PLANE MUST BE MUCH SMALLER THAN  MM /THER #ALCULATIONAL 3TRATEGIES  )NSTEAD OF EXPANDING THE EXPONENTIAL  IN THE INTE 
 For the above values of  B, about 7 minutes of  data was necessary to reach essentially the long-time-averaged characteristic. This is  a reference point about which there will be considerable variation for a typical time  period of interest. For example, with only 1 minute of data the noise power sang would  vary over 0.5 to 1.5 times the long-time-averaged sang. 
 TERMINATED GLACIER WITH AN AREA OF  SQUARE KM 4HE GLACIER DEPTH STARTS AT  METERS AND INCREASES DOWN TO  METERS )N THE BEGINNING OF THE PROFILE  ONLY THE BOTTOM ECHO IS SEEN !T AROUND  KM HORIZONTAL DISTANCE  SOME INTERNAL SCATTERING FROM THE GLACIER IS SEEN 4HIS IS SCATTERING FROM THE FREE WATER INSIDE THE GLACIER &ROM  KM TO  KM  THE BOTTOM ECHO IS DIFFICULT TO SEE DUE TO SCATTERING 4HE THICKNESS OF THE VARIOUS LAYERS OF A ROAD CAN BE MEASURED USING '02 TECHNIQUES  AS SHOWN IN &IGURE  4HE GREAT ADVANTAGE IS THAT THIS METHOD IS NONDESTRUCTIVE AND HIGH SPEED   KMHR  AND CAN BE APPLIED DYNAMICALLY TO ACHIEVE A CONTINUOUS PROFILE OR ROLLING MAP 4HE ACCURACY OF CALIBRATION TENDS TO REDUCE AS A FUNCTION OF &)'52%   %XAMPLE OF '02 IMAGE OF 4-! !4 MINE #OURTESY )%%  &)'52%   %XAMPLE OF !4 MINE IMAGES TAKEN OVER A  M BY  M TEST SITE WITH THE -).$%2 '02  RADAR SYSTEM #OURTESY )%%  . Ó£°În  2!$!2 (!.$"//+  DEPTH BECAUSE OF THE ATTENUATION CHARACTERISTICS OF THE GROUND 4HE ACCURACY MAY BE  QUITE HIGH IE  A FEW MILLIMETERS  FOR THE SURFACE 
 All dynamic cancelers depend on synthesizing a proper amplitude and phase of a signal taken from the transmitter and using this to buck out the spillover sig- nal. To achieve independence of the servos, the vector is synthesized in orthog- onal rectangular coordinates. Figure 14.12 is a typical arrangement for use with a CW radar in which the local oscillator is derived by sidestepping the transmitter. 
 BEAM  PULSED   
 From the radar equation (Eq. 20.2), the SCV can  be scaled to that which would be expected for the main radar, with its different radiated  power PT, aperture, radar bandwidth, etc. Combining these scaled SCV values with  (i) a model of the surface backscattering coefficient versus frequency (almost all the  OTH radar coverage is ocean, so based on regional wave statistics, the constant value  –23 dB is used); (ii) the target RCS versus frequency model; and (iii) an estimate of  the target echo signal processing loss, typically ~ 12 dB, which arises predominantly  from FFT analysis, yields the predicted median target SNR at each spatial location as  ch20.indd   67 12/20/07   1:17:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 G. Trokhimovski, “Gravity–capillary wave curvature spectrum and mean-square slope  retrieved from microwave radiometric measurements (coastal ocean probing experiment),”  J. f Atmosph. 
 CELED  BY USING A TWO 
  TO MEDIUM 
 Asimilar and more important fundamental limitation onbeamwidth isdetermined bythe requirement that atleast one pulse hitthe target perscan, with thebeam axis offinangle from thetarget bynomore than asmall fraction ofthe beamwidth. Atascanning rate of360/see and av,of400, the angular separation between pulses is0.09°, and for. SEC. 
 22, 1973.  37. Bounden. 
 BER REFLECTIONS WERE SUPPRESSED BY A CANCELLATION PROCESS 4HE PROCEDURE IS TO PREPARE THE CHAMBER FOR A MEASUREMENT IN EVERY RESPECT EXCEPT FOR THE INSTALLATION OF THE TARGET ON ITS SUPPORT FIXTURE ! SMALL SAMPLE OF THE TRANSMITTED SIGNAL IS PASSED THROUGH A VARI 
 Damping resistors and appropriately phased diodes areordinarily used forthis purpose. PulseCables.—In handling high-power pulses with steep wave fronts, extreme care must betaken toshield theequipment sufficiently toprevent theradiation ofsignals which interfere with theoperation ofcommunica- tions receivers and other electronic equipment. This shielding isespe. 
 SPONDING PROCESSING IS OFTEN TERMED  FAST 
 51. Ferguson, P., and R. D. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo.  GROUND ECHO  16.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 16.7 SCATTERING COEFFICIENT DATA Numerous programs to gather scattering coefficient data existed prior to 1972, but  sizable data collections with accompanying “ground truth” were rare. 
 ¤ ¦¥³ µ´   CHI 
 A voltage-controlled oscillator (VCO) is used to beat the signal to be analyzed to a convenient intermediate frequency. A narrowband amplifier at this frequency performs the filtering operation. The VCO is in turn controlled by the output of a discriminator connected to the amplifier. 
 , &U AND ! #AZENAVE EDS   .EW 9ORK !CADEMIC 0RESS    PP n  !0,  3PECIAL SECTIONS  h'EOSAT SCIENCE AND ALTIMETER TECHNOLOGY v  *OHNS (OPKINS !0, 4ECHNICAL  $IGEST  VOL   . 
 GRADIENT MEANS OF ATTITUDE CON 
 Inthis arrangement, high voltages appear only inside pressurized spaces, while most oftheheat isliberated intheopen, where itcan becarried away bytheairstream from theexternal blower. Metering andTestPoints.—Good radar performance depends on ob.jective tests ofthe functioning ofeach part. The vital radar com- ponents areallcentralized inther-fhead, and theproviding ofnecessary test points there isapart ofthedesign job. 
 filter were restricted to modeling the target trajectory as a straight line and if the measurement  noise and the trajectory disturbance noise were modeled as white, gaussian noise with zero  mean, the Kalman filter equations reduce to the rx-P filter equations with the parameters ex. and  {1 computed sequentially by the Kalman filter procedure.  The classical a-P tracking filter is relatively easy to implement. 
 Monolithic circuit elements can be viewed as consuming real estate on a GaAs substrate, and the processing complexity of each step determines the relative yield for individual elements. Although typical processing yields for FET devices may exceed 95 percent per millimeter of gate periphery and greater than 99 per- cent per picofarad of capacitance, the net yield for a complex circuit may be quite low. For example, a four-stage power amplifier chip that is capable of 3 W of power output at 2 GHz may require more than 9 mm of total gate periphery and may have a total of 75 pF of blocking, bypassing, and matching capacitance. 
 60. Johnson. J. 
  X\   FROM &IGURE     $$FP LYYP LYYP Ly     N, N, H 2N,H 2COS C OSCOS   &)'52%   )N3!2 
 SUM ELLIPSE AT THIS POINT  ALL SUCH HYPERBOLAS BECOME CONTOURS OF MAXIMUM TARGET DOPPLER L 7HEN C   o A n  THE VELOCITY VECTOR IS POINTED AT THE TRANSMITTER OR RECEIVER AND  F"   6K  COSA    WHICH OCCASIONALLY APPEARS IN THE LITERATURE AS A SPECIAL CASE  OF %Q  )F A MONOSTATIC RADAR IS LOCATED AT THE TRANSMIT SITE AND A BISTATIC HITCHHIKER IS  LOCATED AT THE RECEIVE SITE  BOTH MEASURING TARGET DOPPLER   F- AND F"  RESPECTIVELY  THE  TWO MEASUREMENTS CAN BE COMBINED TO ESTIMATE THE TARGET VELOCITY VECTOR  6  C   IN THE  BISTATIC PLANE /NE SUCH ESTIMATE IS   C   TAN 
 59. Robinson, T. A.: Application of Electronic Distance Measuring Equipment in Surveying, IRE Trans.. 
                   
 (3), P!,isthe peak value ofthe available received power required togive asatisfactory beacon signal onthe indicator ofthe interrogating system, due account being taken ofscanning losses and other circumstances ofuse. The range R;isthegreatest one forwhich reply signals from triggered beacons will beusable. This cannot be defined asclearly asisR!since having asignal “satisfactory” isless definite than having iteither present orabsent. 
 19.6£. This can be accomplished by offsetting either the signal or the reference channel. Figure 19.7 shows the offset reference configuration. 
 4.11 MTI FROM A MOVING PLATFORM  9 When the radar itself is in motion, as when mounted on a ship or an aircraft, the detcctiotl of a  nloving target in tlle presence ofclutter is more difficult than if tile radar were statiollar;~. 'I'llc  doppler frequency shift of the clutter is no longer at dc. It varies with the speed of tlie radar  ~~lutforrn, the direction of the antentla in a~irnt~tli, sn<i tile elevation ittlglc to tl~c clt~tter. 
 Luscombe, and A. A. Thompson, “RADARSAT-2 SAR modes development and  utilization,” Canadian Jour. 
 MON FOR PHASE SHIFTERS AND ATTENUATORS TO EACH HAVE AS MANY AS  BITS OR  DIFFERENT STATES )N ADDITION  ACTIVE COMPONENTS SHOULD BE CHARACTERIZED AT SEVERAL FREQUENCIES IN THE OPERATING FREQUENCY BAND AND OVER SEVERAL TEMPERATURES !S A RESULT  THOUSANDS OF MEASUREMENTS ARE REQUIRED TO FULLY CHARACTERIZE THE PERFORMANCE OF EACH ELEMENT .OT ALL STATES NEED TO BE MEASURED FOR EACH ELEMENT  BUT ELIMINATING MEASUREMENTS AT SOME OF THE STATES WILL CAUSE THE CALIBRATED AMPLITUDE AND PHASE ERRORS TO INCREASE  0HASE SHIFTERS USUALLY EXHIBIT SMALL VARIATIONS IN AMPLITUDE OVER PHASE STATES   WHEREAS ATTENUATORS EXHIBIT LARGE VARIATIONS IN 
 W. Bogle, and D. D. 
    PPn  -ARCH   ( 4 .ICHOLAS ))) AND ( 3AMUELI  h!N ANALYSIS OF THE OUTPUT SPECTRUM OF DIRECT DIGITAL FREQUENCY  SYNTHESIZERS IN THE PRESENCE OF PHASE 
 TOR USING DIFFERENT WEIGHTING FUNCTIONS FOR THE DOPPLER FILTER BANK ARE SUMMARIZED IN &IGURE  )T IS NOTED THAT THE PERFORMANCE OF THE PHASE 
 the input signal may be expressed as  If the minimum detectable signal S,,, is that value of SI corresponding to the minimum ratio of  output (IF) signal-to-noise ratio (So/No~in necessary for detection, then  Substituting Eq. (2.6) into Eq. (2.1) results in the following form of the radar equation:  Before continuing the discussion of the factors involved in the radar equation, it is  necessary to digress and review briefly some topics in probability theory in order to describe  the signal-to-noise ratio in statistical terms. 
 The entire scan  is covered within a single pulse. Hence, the name within-pulse scanning. This is a method for  achieving the equivalent of a multiple-beam array. 
 FIELD TUBE  4HERE IS ALSO A RELATED  CROSSED 
   #HINA  n , -ULTI 
 Losses not readily subject to calculation and which  are less predictable include'those due.to field degradation and to operator fatigue or lack of  operator motivation. Estimates of the?latter type of loss must be made on the basis of prior  56INTRODUCTION TORADAR SYSTEMS Thecosecant-squared antenna hastheimportant property thattheechopowerPr received fromatargetofconstant crosssectionatconstant altitude IIisindependent ofthe target's rangeRfromtheradar.Substituting thegainofthecosecant-squared antenna [Eq.(2.46)]intothesimpleradarequation gives P_P,G2(¢0)csc4¢).2(J csc4¢ r -(41t)3csc4¢oR4=K1-"R4 (2.47) whereK1isaconstant. Theheighthofthetargetisassumed constant, andsincecsc¢=Rill, thereceived powerbecomes (2.4~) (2.49)whereK2isaconstant. 
 57. Mooney, D. H., and W. 
 (21.51) and (21.54). The result of this multiplication is S_ P,G,Ara TjPRFRX N (4Tr)2^r0BFnT0 2v8az . Although Eq. 
 It is introduced directly into the receiver via a cable or other direct connection.  >,  u  C  Q)  :::,  c,­ Q)  \... u.. 
 RecordoftI,eIEEE1975Il1tl.'l'/Ia­ tio/lalRadarCOII(erellce, pp.458-462. IEEEPublication 75CHO938-1AES. 13.Foster,K.:Parabolic Cylinder Aerials,Wireless Ellgr.,vol.33,pp.59-65,March,1956. 
 (When accelera-  tion is important a third equation can be added to describe an a-8-y tracker, where  y = acceleration smoothing ~arameter.)'~ For a = 8 = 0, the tracker uses no current informa-  tion, only the smoothed data of prior observations. If a = /? = l, no smoothing is included at all.  The classical a-8 filter is designed to minimize the mean square error in the smoothed (filtered)  184INTRODUCTION TORADAR SYSTEMS ofpulsesexpected tobereturned fromatargetastheantenna scanspast.Theintegrated pulses arecompared withathreshold toiJidicatethe presence orabsenceofatargetAnexample is thecommonly usedmovingwindowdetector whichexamines continuously theJi!~iJ}~mples withineachquantized rangeintervalandannounces thepresence ofatargetifmoutofrJof thesesamples crossapresetthreshoid. 
 The difference in the two states of magnetization produces the differential phase  Remonen!  mognelizohon ·· C  9  0  ':::!  0,/  C f  Saturation  Applied magnetic field (H) •·············· -•-~-+~~~~- Figure 8.11 Hysteresis loop, or B-H curve, of a ferrite toroid. 29-' INTRODUCTION TO RADAR SYSTEMS  shift. Th is is called a lat chiny plum! shift er. 
 APERTURE SYSTEMS  !S WITH ALL IMAGING SYSTEMS  3!2 IMAGE PRODUCTS ARE RATED ACCORDING TO THEIR RESOLU 
 (2)and (1)weobserve that, ifthefactor jisunity, the effective receiving cross 1Wherever aprecise definition ofbeamwidth isintended, weshall mean the angular interval between twodirections forwhich G=G,/2.. f$Ec. 2.4] THERADAR EQUATION 21 section ofanantenna inthe principal direction isprecisely the area of theaperture; inother words, allthe energy incident onthe aperture is absorbed. 
 Am. Meteorol. Soc. 
 Asforregions well within the horizon, the curvature ofthe earth at most complicates thegeometry oftheinterference problem discussed inthe preceding section. Naturally, wehave noright toapply Eq. (29), asit stands, totargets near thehorizon. 
 ALTIMETER IMPLEMENTATIONl  The altimeter functions as a 13.5-gigahertz nadir­ looking pulse compression radar; major characteristics  are listed in Table 1. The altimeter's two major sub­ systems are an RF section and a signal processor (Fig.  2). 
 , \,)*I>  \ ,,:4  Scattering'from clouda~ost cloud dropleis do not exceed 100 pm in diameter (1 /rrn =  m); consequently Rayleigh scattering may be applied at radar frequencies for the predic-  tion of cloud echoes. In Rayleigh scattering, the backscatter is proportional to the sixth power  502INTRODUCTION TORADAR SYSTEMS Scattering fromsnow.Drysnowparticles areessentially icecrystals, eithersingleorag­ gregated. Therelationship between Zandsnowfallrate,isasgivenbyEq.(13.20)forrain,but withdifferent constants a.andb.Therehavebeenless measurements oftheZ-,relationship for snowthanforrain,andtherehavebeenseveraldifferent valuesproposed fortheconstants (J andb.Thefollowing twoexpressions havebeensuggested Z=2000,2 Z=1780,2.21(13.25a)H (13.25h)75 Measurements showacorrelation between surfacetemperature andthecoefficient aofthe Z=arbrelationship, whichsuggestthefollowing 76 Z=1050r2fordrysnow(avetemp.<O°C) Z=16OOr2forwetsnow(avetemp.>O°C).J(13.26a) (13.26h) Alowersurfacetemperature resultsinalowervalueofthecoefficient a.Stillanother valuethat hasbeensuggested is77 Z=1000,1.6 (13.27) Theredoesnotseemtobeanyagreed-upon value;thereadercantakehispick.Inallofthe above,thesnowfallrate,atthegroundisinmillimeters perhourofwatermeasured whenthe snowismelted. 
 It consists ofasteel tube filled with mercury, with X-cut quartz crystals cemented toitsends bymeans oflacquer. Anend cellfilled with mercury isattached totheoutside ofeach crystal bythesame method. When an alternating voltage isapplied across one ofthecrystals (that is,between themercury intheend cell and that inthetube), thecrystal undergoes periodic changes inthickness due tothe piezoelectric effect. 
  OF 5LABY ET AL  &OR EXAMPLE    FOR # BAND  THE ATTENUATION OF A TYPICAL FOREST CANOPY VARIES FROM  y  D" TO y  D"  THE PROBABILITY THAT THE ATTENUATION IS LESS THAN  D" IS ABOUT  /N THE OTHER HAND  FOR 5(& RADIATION  ATTENUATION VARIES FROM  TO  y  D" HALF THE TIME IT IS LESS THAN  y  D"  4HUS  FOR &/0%.  5(& RADIATION IS NECESSARY SHORTER WAVES WILL NOT PENETRATE THE FOLIAGE  WHEREAS FOR AIRBORNE APPLICATIONS  LONGER WAVES WOULD REQUIRE PROHIBITIVELY LARGE ANTENNAS 3PECIFIC VALUES OF ATTENUATION ;D"METER= VARY WITH GRAZING ANGLE  TREE TYPE  LEAF DENSITY  AND MOISTURE CONTENT HOWEVER  THE PREVIOUS STATEMENT IS A GENERAL SUMMARY OF THESE RESULTS FURTHER DETAILS ARE GIVEN IN &LEISHMAN ET AL   4HE APERTURE TIME  T! REQUIRED TO COLLECT SUFFICIENT DATA  FOR A 3!2 IMAGE IS FOUND F ROM  %Q  &OR EXAMPLE  LET US ASSUME  2    KM  6    MSEC  KTS    PSQ     AND CCR      M &OR F    '(Z 8 BAND   K    M   T!    SEC  AND THE FRACTIONAL BANDWIDTH  "FO      /N THE OTHER HAND  FOR  FO    '(Z 5(&   K    M   T!    SEC    MIN AND  "FO    3UCH A HIGH FRACTIONAL BANDWIDTH AN  ULTRA 
 KM  DOWNRANGE POSITION WILL GI VE PATHS THAT ARE  SLIGHTLY LONG FOR ONE 
 536 INTRODUCTION TO RADAR SYSTEMS  A "figure of merit" that has been used in the past for comparison of OTH radars is the  DBJ value which is defined as the product of Pa, G, G, T,, expressed in dB. The units are joirles  (energy), or dB relative to a joule, hence the name DRJ. It is quite different than the measure of  performance given above. 
 This degrades the autocorrelation function sidelobes somewhat. An examination of se- quences with an inserted O will yield the sequence with the best autocor- relation characteristics. Quadratic Residue Sequences. 
 In order to verify the reliability of the results, the HP-deformation component of the interferogram was analyzed. Compared with the pure linear velocity model, the HP-deformation component of the rheological model was reduced by 34%, indicating that the modeling e ﬀect was eﬀectively improved after adding the non-linear rheological component into the model. The external accuracy was evaluated by ground-level measurements, with an RMSE of ±5.0 mm for the proposed model, an improvement of 53% compared with the pure linear velocity model. 
 I.12  Index terms  Links   CW radar: (Continued)  proximity fuzes 14.20  microwave    14.31  range response tailoring 14.32 14.41  receivers in 14.15  sawtooth modulation for 14.28  short-range systems and 14.31  sinusoidal modulation in 14.23  spectral spreading in 14.2  speedgate for 14.18  stabilization in 14.8  subcarriers in 14.16  target illumination 14.8 14.15  transmitter sources 14.8  triangular modulation in 14.17  CW wave interference 25.2  Cylinder radar cross section of 11.21  D  D region     24.16  Dällenbach layers 11.47  Data processing 1.5  dBZ          23.4  dc operation of CFAs 4.13  Detectability factor 2.6  Detection:  automatic    8.1  probability of 2.8 2.18  cumulative 2.60  in pulse doppler radar 17.36  Detector, nonparametric 8.19  Detector laws 2.23  This page has been reformatted by Knovel to provide easier navigation. I.13  Index terms  Links   Detectors, comparison of 8.23  DF and radar 8.44  Dicke-Fix    9.19  Digital beamforming:  for height finding radar 20.13  in phased array radar 7.8  Digital log power combiner 3.29  Digital logarithm 3.28  Digital MTI 15.53  Digital phase detector 3.38  Digital pulse compression 10.7  Digital range tracker 18.29  Diplex operation 3.54  Dipole, radar cross section of 11.8  Directional wave spectrum 13.3  Directivity of antennas 6.3  Discrete clutter 17.11  Divergence factor 2.42  Dolph-Chebyshev weighting 10.30  Doppler:  in CW radar 14.18  frequency shift 14.2  navigator    14.37  in pulse compression, correction for 10.24  scintillation 18.45  in semiactive missile guidance 19.3  tracking in missile guidance 19.26  weather radar ( see Meteorological radar)  DPCA         16.8 16.16  Dual-band monopulse 18.31  Ducting      13.25  This page has been reformatted by Knovel to provide easier navigation. I.14  Index terms  Links   Duplexer     1.3 4.4  Dynamic range:  of A/D converter 3.40  in MTI radar 15.58  in pulse doppler radar 17.26  of receiver 3.4 3.11  E  E region     24.16  E-2C         16.2  Early-late gate range trackers 18.27  ECCM:  antenna-related 9.7  home-on-jam 19.18  receiver-related 9.18  and signal processing 9.19  in surveillance radars 9.23  in tracking radars 9.25  transmitter-related 9.16  Echo reduction 11.43  ECM          9.2 9.4  and missile guidance 19.30  and terrain bounce 9.27  Effective aperture  of antennas 6.4  Effective earth's radius 2.44 20.17  Electronic warfare 9.2  Electronically Agile Radar (EAR) 7.69  Electronically scanned phased arrays ( see Phased array  radar)  ELINT        9.2  EMCON        9.22  Equalization in pulse compression 10.26  This page has been reformatted by Knovel to provide easier navigation. 
  
 Thus the surest way toobtain reliable performance istooperate thetubes atconservative ratings. Little need besaid here about theinteraction between themagnetron and the r-fcomponents. The relationship between frequency stability, VSWR ofthe r-fsystem, and the magnetron pulling figure has been covered inSec. 
 $#'!) !*     %% "! (  !    .   '2/5.$ 0%.%42!4).' 2!$!2   Ó£°{£  #OOK AND "ERNFELD   2ADAR 3IGNALS  !N )NTRODUCTION TO 4HEORY AND !PPLICATION  .ORWOOD  -!  !RTECH (OUSE  P   - 3KOLNIK  2ADAR (ANDBOOK  ND %D  .EW 9ORK -C'RAW 
 (2.7).  Consider an IF amplifier with bandwidth B,F followed by a second detector and a video  amplifier with bandwidth B,. (Fig. 
 Furthermore, this result can be improved further by processing multiple pulses. TARGET SEPARATION M PUlSEWfDThS FIG. 8.23 Probability of resolution as a function of range separation: sampling rate A/? = 1.5 samples per pulse width; target strengths—nonfluctuating, A1 = A2 = 20 dB; phase differences = 0°, 45°, 90°, 135°, and 180°. 
 ch14.indd   35 12/17/07   2:47:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 
 These differ - ences include adaptation to environment, frequency and waveform selection, radar  cross section, path losses, multipath effects, noise, interference, antenna gain, spatial  resolution, and clutter. For the case of noise-limited detection, the radar equation  takes the form  S NP G G T F L L N Rt r p p s=avl2 3 044σ π( ) (20.2) where  S/N  = output signal-to-noise ratio  Pav = average transmitted power  Gt = transmitter antenna gain  Gr = receiver antenna gain  T  = coherent processing time  l = wavelength  s = target radar cross section  Fp = propagation-path factor  N0 = noise power per unit bandwidth  Lp, Ls = transmission-path and system losses  R  = distance between radar and target ch20.indd   5 12/20/07   1:15:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 E.: Transversal Filters, Proc. IRE, vol. 28, pp. 
 VERTICAL INCIDENCE FROM  CONTOUR MAPS v * 2ES .AT "UR 3TAND  VOL $  PP n    ( $AVIES  h4HE REFLECTION OF ELECTROMAGNETIC WAVES FROM A ROUGH SURFACE v  0ROC )%% ,ONDON     PT   VOL   PP n    ! + &UNG AND 2 + -OORE  h4HE CORRELATION FUNCTION IN +IRCHOFFS METHOD OF SOLUTION OF  SCATTERING OF WAVES FROM STATISTICALLY ROUGH SURFACES v  * 'EOPHYS 2ES  VOL   PP n   . 
    AVERAGE RECEIVED POWER AND  T!   TIME TO FORM THE SYNTHETIC APERTURE  4HE DENOMINATOR OF %Q  IS CORRECT ONLY IF THE TEMPERATURE OF THE RADAR IS THE SAME AS THAT OF THE SCENE  WHICH WE ASSUME SEE #HAPTER  AND 3ECTION  OF 3ULLIVAN    %0' 2T0! !    4X 
 TION OF THE MISSILE IS USED 4HE BANDWIDTH TO THE MISSILE IS VERY LOW AND CAN BE REDUNDANT  AND HIGHLY ENCRYPTED TO PROVIDE GOOD ANTIJAM !*  PROTECTION )F IT CONTAINS IMAGERY  THE UPLINK BANDWIDTH FROM THE MISSILE IS RELATIVELY LARGE AND WILL HAVE COMPARATIVELY LOWER !* PERFORMANCE !N ADAPTIVE -&!2 PRIMARY APERTURE CAN IMPROVE A WIDER BAND MISSILE UPLINK !* IF THE JAMMER IS OFFSET FROM THE TARGET !T THE MISSILE END  THE MISSILE ANTENNA CAN HAVE JAMMER NULLING TO IMPROVE DOWNLINK !*   !'#  #ALIBRATE AND 3ELF 
 MENTS BECOME SIGNIFICANT AND MAY REQUIRE SPECIAL CLOCK REGENERATION CIRCUITRY AT KEY SYSTEM LOCATIONS %FFECT OF 1UANTIZATION .OISE ON )MPROVEMENT &ACTOR   1UANTIZATION NOISE   INTRODUCED IN THE !$ CONVERTER  LIMITS THE ATTAINABLE -4) IMPROVEMENT FACTOR #ONSIDER A CONVENTIONAL VIDEO -4) SYSTEM  AS SHOWN IN &IGURE  "ECAUSE THE PEAK SIGNAL LEVEL IS CONTROLLED BY THE LINEAR 
 Conv. Rec ., New York, NY , October 1969, pp. 294–297. 
 6.14] PRECISION TRACKING OF ASINGLE TARGET 205 Attheoperating frequency of205 Me/see, a4by4array ofdipoles with reflectors gives abeam about 2-1° wide inazimuth and inelevation. Return echoes arereceived ontwo separate antenna arrays, each with its ownreceiver, Onearray, sixdlpoles ~videby four Mgh, @vesinformation toanazimuth scope; the other, two dipoles wide and sixhigh, provides signals toanelevation scope. The receiving arrays have two separate feeds arranged toproduce different phase relations between theelements ofthe array. 
 The paraboloid antenna reflector oftheAN/APS-4 is14in.indiameter. Inallthese equipments, the360° azimuth scan of theArmy equipments isreplaced byawide sector scan centered along the line-of-flight oftheaircraft, and covering about 160° inall. Atthewill ofthe operator, this scan can bereplaced byanarrow sector scan exe- cuted more rapidly. 
 15.1 is the magnitude K = (Kx2 + Ky2)1/2. The wavenumber spectrum  associated with S(  f  ) is a function of the two components of K and is commonly writ - ten as W(Kx, Ky). This is called the directional wave spectrum  and expresses the asym - metries associated with winds, currents, refraction, isolated swell components, etc. 
 In wartime conditions this new frequency, known as the  XF frequency, was usually switched on suddenly just  before the first bombers were about to reach their  target. While the enemy listening stations were dis-  covering the XF and the jammers scrambling around to  retune their transmitters to jam this new channel Allied  navigators could get their fix, and so find their last  short stage to the target.  Oboe, like Gee, is virtually a radar beacon. 
 02& RADAR THAT CAN MEASURE DOPPLER  UNAMBIGUOUSLY OVER THE SPAN OF RADIAL VELOCITIES OF INTEREST  BUT IS USUALLY HIGHLY  AMBIGUOUS IN RANGE ! MEDIUM 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.8  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 analog (20 MHz, offset video), to be converted on the ground to either optical media  (transparent film strips) or digitized (5-bit quantization). Imagery was generated (but  not immediately†) by either optical or digital processing methods. 
 This is well known to  the radar receiver designer. The rule of thumb quoted in pulse radar practice is that the . 370 INTRODUCTION TO RADAR SYSTEMS  receiver bandwidth 8 should be approximately equal to the reciprocal of the pulse width r. 
 With this  € Rt should be so large that the object lies in the far field of the impinging waves as  well should  € Rr→∞(approaching infinity) so that the receiving antenna lies in the far field of  the scattering body.  If one expresses σ from Equation (11.1) as a relationship of the electric  field strength at the receiving antenna to the field strength of the inci dent plane wave front at  the object, then the result is:      € σ=4π⋅limR2 R→∞⋅  E S⋅  E S*   E i⋅  E i* (11.2)  Where s=scattered and i=incident.   Usually the cross- section is based on an area of 1m2 and is stated in dB as  € σ/dBm2=10logσ 1m2        . 
 The configuration or Fig. 4.9a is called a double-delay-line canceler, or  simply a double canceler. The relative response of the double canceler compared with that of a  single-delay-line canceler is sho..yn in Fig. 
 AES- 7, pp. 269-278, March 1971. 7. 
 P., and J. Eckerman: A System Concept for Wide Swath Constant Inci- dent Angle Coverage, Proc. Synth. 
 The observed reflected signal characteristics were  consistent with normal lunar regolith‡ on three passes, but data from the fourth pass  ‡  Found virtually everywhere on the Moon’s surface, regolith  is a layer of granular rocky material covering   solid rock. ch18.indd   46 12/19/07   5:15:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 (1) (3).)1”,cCALC,,Utl,l,,edLII,e,, bUii,,lJ~,UU,,UIll“1,,,~~““”KSUlLILISSSlltX)~h~CL-l?llly Micrwave Transmission Circuits,vol. 9;(z)Microwave hpk%rs, ~01. 14; Wavegwid. 
 Both are more suited for electronic scanning in one angu­ lar coordinate than for two-angle-coordinate electronic scanning. Thus they are of interest for  determining elevation angle in JD radar. In one method,66 a frequency-scan beam is rapidly  swept through the angular region of interest. 
 In extending the radar equation to meteorological targets.  it is assumed that rain. snow, hail. 
 ORDER SCATTER AT (&  THAT IS n KNOTS /F THE VARIOUS NONDIRECTIONAL OCEAN WAVE MODELS REPORTED IN THE LITERATURE  THAT  OF 0IERSON AND -OSKOWITZ HAS BEEN MOST WIDELY USED BY THE RADAR COMMUNITY 4HEY DERIVED THE FOLLOWING RELATION FOR A FULLY DEVELOPED NONDIRECTIONAL SPECTRUM BASED UPON EMPIRICAL DATA    &EC  E X PJA JJ J 
    2 & &ITZGERALD  h3IMPLE TRACKING FILTERS 3TEADY 
 METRIC CHANGES IN THE GEOMETRY OR CONFIGURATION OF AN OBJECT  OR IN THE ANGLE OF ARRIVAL OR OF THE FREQUENCY  OF THE INCIDENT WAVE 4HIRD  THE SOLUTIONS FOR SOME OBJECTS MAY CONTAIN SPURIOUS RESONANCES THAT DO NOT ACTUALLY EXIST  THEREBY REDUCING THE CONFIDENCE ONE MAY HAVE IN APPLYING THE METHOD TO ARBITRARY STRUCTURES &IGURE  SHOWS A -/- 
 However, hesees all other targets intheairwithin range ofhisradar. The controller inthe SCR-584 sees the position ofhisaircraft continuously, and inproper relation totheterrain, but theprice paid forthis isthat hehasnoknowl- edge ofthewhereabouts ofother aircraft.. SEC. 
 RANGE DETECTION PERFOR 
 This is deliberate and is necessitated by brevity. More detailed  information will be found in some of the subsequent chapters or in the references listed at the  end of the chapter.  '. 
 ¤ ¦¥³ µ´ L O G    P   ATMOSPHERES BAROMETRIC PRESSURE IN MILLIBARS 4   ATMOSPHERES ABSOLUTE TEMPERATURE IN +ELVINRH   ATMOSPHERES RELATIVE HUMIDITY IN PERCENT. ÓÈ°{  2!$!2 (!.$"//+  4HUS  THE ATMOSPHERIC REFRACTIVITY NEAR THE %ARTHS SURFACE WOULD NORMALLY VARY  BETWEEN  AND  . 
 A., and D. C. Stoner: ECCM from the Radar Designer's Viewpoint, paper 30-5, lEEE  ELECTRO-76, Boston, Mass., May 11-14, 1976. 
 DARD DEVIATION OF THE TRACKING ERRORS DUE TO MEASUREMENT NOISE IS REDUCED BY THE SQUARE ROOT OF   ALLOWING A LARGER GAIN TO BE SELECTED OPTIMIZATION MORE TO THE RIGHT OF THE BATHTUB   REDUCING THE LAG 4HE NET RESULT IS THE MOVEMENT FROM THE SINGLE RADAR CURVE TO THE TRACK FUSION CURVE IN &IGURE  )F THERE IS ANY SIGNIFICANT MANEUVER POSSIBLE  THE FACTOR OF  IN LAG WILL HAVE A MORE  SIGNIFICANT EFFECT THAN THE FACTOR OF THE SQUARE ROOT OF  IN THE SQUARE ROOT OF THE TRACKING ERRORS DUE TO MEASUREMENT NOISE 4HUS  ONE CAN SEE THE DETECTION FUSION CURVE ACHIEVES A SIGNIFICANTLY LOWER MINIMUM THAN THE TRACK FUSION CURVE 4O COMBINE DATA FROM MULTIPLE RADARS  THE DATA MUST BE PLACED IN A COMMON COOR 
    
 RECEIVE 
 The IF hybrid, adding or subtracting another 90 ° differential, causes the high-sideband  signals to add at one output port and to subtract at the other. Where wide bandwidths  are involved, the IF hybrid is of the all-pass type. In practice, image reject mixers often  do not provide sufficient rejection of the image response alone without filtering. 
 The log-FTC has the property that when the input clutter or noise is described by a  Rayleigh pdf, the output clutter or noise is a constant independent or the input amplitude.  Thus the log-FTC receiver has a constant false-alarm rate. As with any CF AR, the false-alarm  rate is maintained constant by a sacrifice in the probability of detection. 
 If the transmitter power supply incorporates high-frequency ac-dc and/or dc-dc  converters, and if the converter frequency components are not sufficiently filtered,  there will be discrete time sidelobes, offset from the clutter in range, as predicted by  paired-echo theory.42 The paired-echo sidelobes will also have a doppler frequency  equal to the converter frequency. This frequency (  fconv) will alias into the PRF (  fr)  doppler interval at the frequency (  fdop) [ fdop = modulo (  fconv,  fr)]). These sidelobes will  not cancel unless the high-frequency converters are synchronized to a multiple of the  PRF, in which case fdop = 0. 
 Antenna stabilization isalso desirable inaircraft, tocorrect fortheeffects ofchanges inattitude; but itissocostly inweight and complication that ithas been seldom used. Typical examples ofPPI radar systems intended forground and for airborne useareanalyzed indetail inChap. 15. 
 '· · -R = 4 !if (3.13) . l'W i\Nl> FRl'<)llFNC'Y-MODULJ\TED RADAR 87  wltcre R = range (altitude). m  c = velocity of rroragation. 
 V.: Prediction of Radar Range. cliap. 2 of " Radar. 
 TIME ADAPTIVE PROCESS 
 mm/hr /  /  /  100 RADAR CLUTIER 501  Figure 13.12 Exact (solid curves} and  approximate (dashed curves} back­ scattering cross section per unit volume  of rain at a temperature of l8°C Exact  computations obtained from F. T.  Haddock, approximate curves based  on the Rayleigh approximation. 
 Lv, X.; Xing, M.; Wang, C.; Zhang, S. ISAR imaging of maneuvering targets based on the range centroid Doppler technique. IEEE T ran. 
 ERROR 
 GATE AND DOPPLER 
 A common method for pulsing the beam of a  klystron is with an electrode in the electron gun that controls the klystron-beam current. This . RADAR TRANSMITTERS 203  is the mod11/<1ti11q m1ode. 
 The voltage derived from the velocity measurement was used to control the position of the strobe, allowing it to follow a target as the range reduced. The rangemeasurement was fed to the pilot ’s indicator where it actuated the range meter, calibrated in nautical miles. If the signal disappeared the scanner and strobe remained ﬁxed for one or two seconds, so that if the target reappeared the equipment could have re-locked itself. 
 13.6. Amp~ers.-X’o attempt will bemade here todescribe the standard forms ofamplifier met with inordinary vacuum-tube circuit E,.-L?E.ut Adding 4 -cwcuitAmphfier- E,n gain=lgem=Go +R, -BEc,u, R=R+,R2 *4 QAmphfier Elm R, –BEM E Load 0“’ R2 FIG. 13.10.—Negative feedback principle.practice, but anumber ofspecial forms important inindicator de- sign will betouched upon. 
 PATH 
 Microwave J., vol. 5, pp. 76-85, August, 1962. 
 The equation relating  the error to the SNR and system parameters is  στ βrt/ /ft(rms) = k S N fr r n ( ) (9.12) where t = pulse length in ft  kr =  range-error-detector sensitivity (maximum value of 2.5 for a receiver  where B = 1.4)  S/N = signal-to-noise ratio  bn = servo bandwidth Other Internal Sources of Error.  There are many other sources of internal errors  that are small in well-designed tracking radars. These include changes in relative phase  and amplitude between monopulse receiver channels as a function of signal strength,  ch09.indd   42 12/15/07   6:07:58 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 1978.  69. Varela, A. 
 QUENCY  OR $# DIRECT CURRENT  AFTER BASEBANDING 4HE SAME EFFECT COULD BE OBTAINED BY SHIFTING THE RECEIVER ,/  FREQUENCY 7ITH THE CLUTTER AT $#  THE SPURIOUS SIGNALS  CAUSED BY CERTAIN RECEIVER NONLINEARITIES   SUCH AS MIXER INTERM ODULATION PRODUCTS AND  VIDEO HARMONICS  ALSO FALL NEAR $# AND CAN BE FILTERED OUT ALONG WITH THE MAIN 
   HOWEVER  WAS THAT IT COULD INCLUDE SPARE SOLID 
 TO 
 desiredpattern isaminimum, andthcWoodward-Levinson method givesanantenna pattern whichcxactlyfitsthcdesircdpatternatafinitenumberofpoints. 1>()II)h-C1ll'hlSIH.·~' arrays. AOA.\Thispatternproducesthenarrowest beamwidt hforaspecifled sidelohe level.Theheamwidth ismeasurcd bythedistance betwecn thefirstnullsthatstraddle themainbeam.Thesidelobes arcallofequalmagnitudc. 
 njr~mjD. The various doppler sidebands and most ofthenoise arenow removed bypassage through afilter that passes only j,and itsmultiples, whereupon the voltage atPoint 4has aform like that shown inFig. 5.17d. 
 On transmission, the  directive antenna channels the radiated energy into a beam to enhance the energy con­ centrated in the direction of the target. The antenna gain G is a measure of the power radiatcd  in a particular direction by a directive antenna to the power which would have been radiati.:d  in the same direction by an omnidirectional antenna with 100 percent efficiency. More  precisely, the power gain of an antenna used for transmission is  G(n "') = pow~r radiated per unit solid angle in azimuth O and elevation <j)  o, 'I' d b f . 
 E. Schrank, “Low sidelobe radar antennas,” Microwave J ., pp. 109–117,  July 1983. 
 The sudden termination ofitscurrent results inanoscillation ofLand its associated capacity. The plate end ofthe inductance swings positive, disconnecting V,asthe potential rises past the 200-volt level. Onthe down-swing, V2becomes conducting again and clamps theinductance to the 200-volt point, resulting inthewaveform shown. 
 The digital outputs of the I and Q channels are  combined by taking the square root of /2 + Q2• An alternative method of combining, which is  adequate for most cases, is to take I I I + IQ j. The combined output is then converted to an  analog signal by the digital-to-analog (D/A) converter. The unipolar video output is then  ready to be displayed. 
 For this, an accurate estimate, ˆ ,fd i, of the  ambiguous target radial velocity must be obtained at the range corresponding to  the ambiguous primitive target detection on each CPI. This frequency estimation  problem has been studied by many authors with the best approach being defined  ch02.indd   89 12/20/07   1:47:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Find the signal-to-noise ratio from Fig. 2.7 corresponding to the desired value of detection  probability Pd and false-alarm probability Pr •.  2. 
 108. Pelton, E. L., and B. 
 (1) Total gate periphery is usually at a premium. For high- power design, the load impedance presented to the final device must be carefully chosen such that power output and efficiency are maximized. (2) Losses in the output circuit of the final stage can significantly reduce power output and effi- ciency. 
 It is an economical alternative to a full two-dimensional array. Shaped Reflectors. Fan beams with a specified shape are required for a variety of reasons. 
               #  ' (" % !('' %$ & $ &    # "!('' % !' '(  ! #     !$ !('' %)!('' % %  *   $#  !' %(" %  $ #'   
 The so-called A15193F Coaxitron, described in Vingst et al.,42 operated over a  frequency range from 406 to 450 MHz with a peak power of 1.25 MW, a pulse width  of 13 µs, a duty cycle of 0.0039, an average power of just under 5 kW, and a plate  efficiency of 47%. The Coaxitron has been successfully employed for UHF radars,  including airborne. Constant Efficiency Amplifier (CEA). 
 24.Weiss,H.G.:TheHaystack Microwave Research Facility, SpeClrll1ll, vol.2,pp.50-59,h:bruary, 1965. 25.Josefsson, L.G.:ABroad-band TwistReflector, IEEETrailS.,vol.AP-19,pp.552-554, July,1971. 26.Lo,Y.T.:OntheBeamDeviation FactorofaParabolic Reflector, IREnam.,vol.AP-8, pp.347-349, May,1960. 
 For practical purposes, however, the signiﬁcantfactor is the rate of precipitation, because the water content of the heaviest snowfall will very rarely equal that of even moderate rain. It is important to keep in mind that in areas receiving and collecting snowfall and where the snow is collecting on possible danger targets it mayrender them less detectable. Accumulation of snow produces a limitedabsorption characteristic and reduces the detection range of an otherwisestrong target. 
 MENTING A LOW 
 NOISE RATIO EXCEEDS THE DYNAMIC RANGE 3IMILAR LOGIC CAN BE APPLIED TO SATURATED RANGE GATES TO DETERMINE IF THE LARGEST SIGNAL IN THE FILTER BANK IS IN THE PASSBAND OR REPRESENTS SATURATED CLUTTER RETURNS 3ATURATED RETURNS WITH THE PEAK SIGNAL IN THE DOPPLER PASSBAND CAN REPRESENT VALID TARGETS AT SHORT RANGES AND NEED NOT BE SUBJECTED TO THE SIDELOBE BLANKING LOGIC 4HE MOST STRESSING DYNAMIC 
 When  the phase at one end or the concentric line is increasing, the phase at the other end is  decreasing. Hence one line can supply the necessary phase variation to two elements, one on  either side or array center. A total or N/2 concentric rings are required for a linear array of  N + I elements. 
 90". 45". 22.5". 
 Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 1.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 a military radar with low probability of intercept at these frequencies than at lower  frequencies. In the past, millimeter wave transmitters were not capable of an average  power more than a few hundred watts—and were usually much less. 
 L.: Metaldetecting Radar Rejects Clutter Naturally, M~crowaves, vol. 15, pp. 12-14, August,  1976. 
 G. Wiley, ELINT: The Interception and Analysis of Radar Signals , Norwood, MA: Artech  House, Inc., 2006. 17. 
 According y theradar, which had originally been intended forairwarning from afixed site, was provided with facilities, sketched inSec. 7.6, which made it suitable asamobile radar control center foruseinoffensive airwarfare. Apart from theaddition ofagreater number ofindicators than would have been needed forsimple airwarning, and the provision ofoff-center PPI’s forthe use ofcontrollers, the modifications made inthe setitself tofititforitscontrol function were notextensive orimportant. 
 Ocean. Technol .,   vol. 4, pp. 
 CONTROLLED TUBES  ARE TAKEN ADVANTAGE OF IN LINEAR 
 OUS MATTER WHEN IT COMES TO OBTAINING A LICENSE TO RADIATE 3ECOND  THERE ARE RADAR  APPLICATIONS BEYOND BASIC TARGET DETECTION WHERE EXTREMELY HIGH SPECTRAL PURITY IS ESSENTIAL  AS WITH DETECTION OF SMALL SHIPS AT LOW SPEEDS 4HIRD  THE ANTENNA DESIGN MUST BE ABLE TO HANDLE HIGHER FIELD STRENGTHS WITHOUT ARCING AND SPARKING  WHICH INTRODUCES NOISE &OURTH  UNLIKE THE &- 
 PROCESSING PERFORMANCE   THEY ARE OF RELATIVELY LOW GAIN WHICH REQUIRES THE TRANSMITTER TO HAVE MULTIPLE STAGES   AND BECAUSE THE KLYSTRON IS USUALLY A BETTER OVERALL CHOICE +LYSTRON 4HE ORIGINAL KLYSTRONS EMPLOYED RESONANT CAVITIES THAT RESTRICTED THEIR  BANDWIDTH 4HE BANDWIDTH OF A KLYSTRON  HOWEVER  INCREASES AS ITS POWER INCREASES 2ESONANT CAVITIES WERE LATER REPLACED BY WIDER 
 Figure 10.6b depicts the currents and fields atthis instant. fCoaxiallineoutput ~Frontpolepiece ,Permanent magnet FIG. 10.5.—Magnetron with axial cathode andinserted polepieces. 
 3.Theleakage.signalentering thereceiverviacoupling between transmitter andreceiver antennas. Thiscanlimittheultimate receiversensitivity, especially athighaltitudes. 4.Theinterference duetopowerbeingreflected backtothetransmitter, causingachangein theimpedance seenbythetransmitter. 
 3ofthis series. RADAR-BEACON SYSTEMS 8.1. Types ofRadar-beacon Systems.—In adiscussion ofbeacons itisconvenient toclassify them asfixed ground beacons, shipborne beacons, airborne beacons, and portable beacons. 
 PHASE AND OUT 
 COMPENSA 
 Dunbar, A. S.: Calculation of Doubly Curved Reflectors for Shaped Beams, Proc. I RE, vol. 
 A  change in frequency will change the location of the nulls and lobes so that by operating  over a wide frequency range, the nulls in elevation can be filled in, and the radar will  be less likely to lose a target echo signal. For example, measurements with a wideband  experimental radar known as Senrad, which could operate from 850 to 1400 MHz,  showed that when only a single frequency was used, the blip-scan ratio (the experi - mentally measured single-scan probability of detection) was found to be 0.78 under a  particular set of observations. When the radar operated at four different widely sepa - rated frequencies, the blip-scan ratio was 0.98—a highly significant increase due to  frequency diversity.2 Increased Target Detectability. 
 of receive  channels32 480 82 372 48 5 Rx azimuth  beam steer± 45° ± 45° ± 30° ± 45° 360° Waveform type Linear FM/CW Linear FM/CW Linear FM/CW Linear FM/ CW Linear  FM/CWCoded pulse Binary phase  coded pulse Waveform  repetition  frequency (Hz)~ 4–80 ~ 4–80 10–60 5–60 10, 16, 20 Waveform  bandwidth(kHz)4–40 typical 4–40 typical 5–40 4.17–100 40 Coherent  integration   time (s)1.5– 5 Air  mode 15–40 Ship  mode1.5–15 Air  mode 15–40 Ship  mode0.7–20.5 1.3–49.2 Primary mission Aircraft  detectionAircraft  detectionAircraft  detectionAircraft  detectionAircraft  detectionBallistic  missile  detection Secondary  missionsShip detection Remote  sensingShip detection Remote  sensingCruise missile  detectionShip  detectionShip detection Remote  sensingAircraft  detection Cruise missile  detectionTABLE 20.2  Principal Design Parameters for Some Major HF Skywave Radar Systems,   Past and Present   (This information has been compiled from sources that, in some cases, are incomplete. Where only  partial information is provided, it may still be useful for comparison purposes. Notes: (i) VLPA  denotes vertical log-periodic antenna and (ii) 2-band ( n-band) linear arrays are usually constructed as  contiguous collinear arrays.) ( Continued ) ch20.indd   12 12/20/07   1:15:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 SPL TR  66–1, 1966. This report is reproduced in IEEE Trans ., vol. AP–24, pp. 
 Frequency shifted   signal 4. Real lowpass filter  response 5. Complex baseband   signal 6. 
 Theresultant radiation pattern istheproductoftheelementfactorGe(O)andthearrayfactorGa(O),thelatterbeingthepattern ofanarraycomposed ofisotropic elements. Thearrayfactorhasalsobeencalledthespace. 282 INTRODUCTION TO RADAR SYSTEMS  fucror. 
 At near vertical incidence (4 % 90") the radar echo is relatively large.  This is called the quasi-specular region and seems to be the result of specular scatter from  facetlike surfaces oriented perpendicular to the direction of the radar. At the other extreme,  when the grazing angles are low, of the order of several degrees or less, 0' decreases very  rapidly with decreasing angle. 
 23. M. Selinger, “U.S. 
 13.8) shows that, all other factors remaining constant, the shorter the pulse  width the greater will be the maximum· range. Decreasing the pulse width decreases the  amount of clutter with which the target must compete. There are three cautions to remember,  however, when considering the use of Eq. 
 )NTERFERENCE PLUS .OISE 2ATIO 3," 3IDE,OBE "LANKING 3,# 3IDE,OBE #ANCELER 3.2 3IGNAL 
 11, no. 21, p. 507, Oct. 
 Thonlas. H. W., N. 
 During normal operation the magnetron would drift in frequency and regular re-tuning of the LO frequency was necessary. This was achieved with the tuning control which physically adjusted plungers in the klystron cavity. The LO would be tuned for maximum response of a strong target on the height tube with the antennastationary or a large target such as land on the PPI when scanning. 
 TIME &IG  BnE   FRE 
 VII 5-1 References 5-3 6 Lucero 6-1 6.1 The Lucero interrogator 6-1 6.2 Lucero trials results 6-4 References 6-5 7 Comparative performance assessment 7-1 7.1 Introduction 7-1 7.2 ASV Mk. II and III 7-1 7.3 ASV Mks III, VI and VII 7-2 7.3.1 Comparative trials 7-3 7.3.2 Predicted performance of ASV Mks III, VI and VII 7-5 References 7-13 8 Conclusions 8-1 8.1 Other ASV radars 8-1 8.1.1 USA radars [1] 8-1 8.1.2 ASV for Coastal Command strike aircraft and FAA 8-3 8.2 The schnorkel 8-4 8.3 Coastal Command at the end of WWII 8-5 References 8-5Airborne Maritime Surveillance Radar, Volume 1 ix. Preface Maritime reconnaissance aircraft are operated around the world by maritime nations. 
 ITY  CAN DETERMINE THE UPPER LIMIT OF PERFORMANCE OF THE DEVICE IN TERMS OF RUGGEDNESS  EFFICIENCY  AND SATURATED POWER OUTPUT 4HE FUNDAMENTAL LIMITATION ON HIGH 
 299–330, March 1973. 19. A. 
 FT DISH  FOR EXAMPLE  CAN PROVIDE A  SERVOSYSTEM BANDWIDTH UP TO  OR  (Z WITH CONVENTIONAL DESIGN ,OCKE DESCRIBES METHODS FOR CALCULATING ANGLE TRACKING LAG FOR A GIVEN TARGET  TRAJECTORY VERSUS TIME AND SET OF SERVOSYSTEM CHARACTERISTICS 2ANGE TRACKING LAGS MAY BE SIMILARLY CALCULATED  BUT WITH TYPICAL INERTIALESS ELECTRONIC TRACKING SYSTEMS  TRACKING LAGS ARE USUALLY NEGLIGIBLE %LECTRONICALLY STEERABLE ARRAYS PROVIDE A MEANS FOR INERTIALESS ANGLE TRACKING  (OWEVER  BECAUSE OF THIS CAPABILITY  THE SYSTEM CAN TRACK MULTIPLE TARGETS BY RAPIDLY SWITCHING FROM ONE TO ANOTHER RATHER THAN CONTINUOUSLY TRACKING A SINGLE TARGET 4HE TRACKER SIMPLY PLACES ITS BEAM AT THE LOCATION WHERE THE TARGET IS EXPECTED   CORRECTS FOR THE POINTING ERROR BY CONVERTING ERROR VOLTAGES WITH KNOWN ANGLE 
 Applications that utilize hard limiting, including  phase-detectors and phase-monopulse receivers, are described in Section 3.10 of the  second edition1 of this handbook. Modern radar systems are mostly designed to maxi - mize the linear operating region, with limiters used only to handle excessively large  signals that inevitably exist under worst case conditions. Characteristics. 
 on Synthetic Aperture Radar , Friedrichshafen,  Germany, May 25–27, 1998, pp. 391–394. 169. 
 Time-multiplexing.  If the transmitter’s beam scanning schedule is known, the  number of receive beams (and RSPs) can be reduced in some geometries by time- multiplexing them to cover only the currently illuminated surveillance sector.   FIGURE 23.10  Beam scan-on-scan coverage problem shown in  two dimensions in the bistatic plane2 (Courtesy SciTech ) ch23.indd   27 12/20/07   2:21:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The tradeoff for selecting PRFs is that in a dense target environment, when try - ing to resolve true radial velocity using different PRFs, “ghosts”§ may be created.  FIGURE  2.93 Illustrative acceptance/rejection criteria of SVCFighter  Aircraft  Waves Helicopter  Missile  Radial Velocity (knots) General  Aviation  T Cross Section - dBsm ACCEPT ACCEPT  Birds Commercial  Airliner  0 Positive Negative REJECTWaves  Birds TWA  §  “Ghosts” occur when targets (or noise peaks) at different unambiguous ranges fold into the same, but incorrect,  true range cell. The velocity resolution algorithm then gives an incorrect result, and the ghosts may be declared as  threatening targets. 
 120. Greneker. E. 
 SEC.2.10] THESTATISTICALPROBLEM 37 signal Srni.. One can never beabsolutely sure that any observed peak is not due toachance noise fluctuation, and one cannot even say how probable itisthat the peak isnot due tonoise, unless one knows how probable itis,apriori, that thepeak isdue tosomething else-namely, signal plus noise. Knowledge oftheapriori probability ofthepresence ofsignal ispossible incontrolled experiments such asthose described in Vol. 
 TER OBSERVED BY 3)2 
 [ CrossRef ] 26. Nikos, S.; Ioannis, P .; Constantinos, L.; Paraskevas, T.; Anastasia, K.; Charalambos, K. Land subsidence rebound detected via multi-temporal insar and ground truth data in kalochori and sindos regions, northern Greece. 
 CENTERED  AND  TRANSMITTER 
 6. Reed. ti. 
 Summary oferrors.Thecontributions ofthevarious factorsaffecting thetracking error aresummarized inFig.5.14.Angle-fluctuation noisevariesinversely withrange;receiver noisevariesasthesquareoftherange;andamplitude fluctuations andservonoiseare independent ofrange.Thisisaqualitative plotshowing thegrosseffectsofeachofthefactors. Twodifferent resultant curvesareshown.CurveAisthesumofalleffectsandisrepresentative ofconical-scan andsequential-Iobing tracking radars.CurveBdoesnotincludetheamplitude fluctuations andistherefore representative ofmonopulse radars.InFig.5.1theamplitude fluctuations areassumed tobelargerthanservonoise.Ifnot,theimprovement ofmonopulse tracking overconicalscanwillbenegligible. Ingeneral,thetracking accuracy deteriorates at["bothshorlandlonglargetranges,withthebesttracking occurring atsomeintermediate range .·-JFrequenCy agilityandglintreduction.35-40,85Theangularerrorduetoglint,whichaffectsall tracking radars,resultsfromtheradarreceiving thevectorsumoftheechoescontributed by theindividual scattering centersofacomplex target,andprocessing itasifitwerethereturn fromasinglescattering center.Ifthefrequency ischanged, therelativephasesoftheindividual I.­o L.. 
 ch15.indd   4 12/15/07   6:16:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter. 
    . {°£ä  2!$!2 (!.$"//+  FILTERS FOR EACH RANGE GATE RESULTING IN A RANGE 
 II in a Coastal Command Beau ﬁghter, Technical Note No. 103, Radio Department RAE, June 1943 (TNA AIR 6/12308)Airborne Maritime Surveillance Radar, Volume 1 2-24. [11] Report on Prototype Installation of ASV Mk. 
 IMO performance standards and the SOLAS Convention are regularly revised, so it  is important to check the current status of the standards. IEC 6238811 defines the tech - nical and test standards based on the IMO radar performance standards. IEC standards  also undergo regular revision. 
 Roll is the side-to-side angular motion around the longitudinal (fore-and-aft) axis of the ship or  aircraft. Pitch is the alternating motion of the fore and aft (bow and stern) parts of the vehicle.  Yaw is the motion of the platform around the vertical axis. 
 Thus, the remainder of this chapter will concentrate on the bistatic  radar topic, developing multistatic excursions and deviations only when necessary . Passive receiving systems, or electronic support measure  (ESM ) systems, often  use two or more receiving sites. Their purpose is typically to detect, identify, and  locate transmitters such as those from monostatic radars. 
 .I'tiis rcsilits in it strong duct along tlie i~iterface of the temperature inversion. In sorne  c;~scs. ;I st I.;I~~IS clo~~d 1;lyer will fo1.111 i~t tile base of tile temperature in~ersion.~' T11t1s tlie duct  ;tltiti~dc call hc idcritificd by tlic licigl~t of tlie cloud tops tliat are suppsesscd by tlic tc~iii~cra-  turc iriversiorl. 
 Monog. 92, pp. 59-76, March 1966. 
 SATION  -AIN AND GUARD CHANNELS ARE PROCESSED IN THE SAME WAY /BVIOUSLY  THE TWO  SPECTRA ARE QUITE DIFFERENT AND SEPARATE FALSE ALARM AND NOISE ENSEMBLE ESTIMATES ARE MADE 4HIS LEADS TO SEPARATE THRESHOLD SETTINGS -ULTIPLE CHANNELS ARE USED TO ESTIMATE INTERFERENCE AND SELECT %##- STRATEGY -AIN CHANNEL DETECTIONS ARE EXAMINED FOR '-4S AND CENTROIDED IN RANGE AND DOPPLER BECAUSE A RETURN IN RANGE OR DOPPLER MAY STRADDLE MULTIPLE BINS  THE CENTROID OF THOSE RETURNS IN MULTIPLE BINS MUST BE ESTIMATED FROM THE AMPLITUDE IN EACH BIN AND THE NUMBER OF BINS STRADDLED  4HE GUARD CHANNEL IS DETECTED AND THE THRESHOLDED RESULTS ARE USED TO GATE THE MAIN CHANNEL RESULTS FOR THE FINAL HIT 
 SPREAD FUNCTION  03&  IN THE RADAR IMAGE  SO 
 12.8.) The measure of receiver internal noise is the noise-figure (introduced  previously in Sec. 2.3).  Good receiver design is based on maximizing the output signal-to-noise ratio. 
 pp. 43 5l 139 147, Mar.. 1957. 
 R. Klemm, Principles of Space-Time Adaptive Processing ,” London: IEE, 2002. 26. 
 7 VELOCITY COMPONENT IN THE ASCENDING PASS IS CONTRARY  TO THE DIRECTION OF THE %ARTHS ROTATION  IN CONTRAST TO PROGRADE ORBITS WHOSE INCLINATIONS ARE LESS THAN n. 
 Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  131              Figure 12.26  (Left) Original signal spectrum (gray) and total filter amplitude  response with added digital reciprocal ripple compensation. (Right)  Signal sp ectrum after Bessel and reciprocal ripple filtering.       Figure 12.27  Amplitudes of FIR weights of exact phase -only Matched filter plus reciprocal  ripple filter and truncated version used to obtain output response in  Figure  12.29 and 12.30. 
 The combined velocity and acceleration characteristics of a servosystem can  be described by the frequency response of the tracking loop, which acts essentially like  a low-pass filter. Increasing the bandwidth increases the quickness of the servosys - tem and its ability to follow a strong, steady signal closely. However, a typical target  causes scintillation of the echo signal, giving erroneous error-detector outputs, and at  long range, the echo is weak, allowing receiver noise to cause additional random fluc - tuations on the error detector output. 
 These operations of an ADT are usually implemented with digital computer  technology.  A common form of radar antenna is a reflector with a parabolic shape, fed (illuminated)  from a point source at its focus. The parabolic reflector focuses the energy into a narrow beam,  just as does a searchlight or an automobile headlamp. 
 A. Studer, M. Toma, and F. 
 There are a number of other mechanisms, which cause a separa - tion of positively and negatively charged ions resulting in electric polarization. These  mechanisms can be associated with ionic atmospheres surrounding colloidal particles  (particularly clay minerals), absorbed water, and pore effects, as well as interfacial  phenomenon between particles. The general form of the model that describes the frequency dependence of such  systems is the Debye19 relaxation equation:  ′−′′= +− +∞∞ε ε εε ε ωτiis 1 (21.1) where  e′ is the real part of the dielectric permittivity,  e′ = real part of the dielectric permittivity  e″ = imaginary part of the dielectric permittivity  e∞ = high frequency limiting value of the permittivity ch21.indd   6 12/17/07   2:51:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 6.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 be at IF, where it affects I and Q channels identically, not at baseband. Video filter  bandwidth should be more than half the IF bandwidth and controlled by precision  components in order to minimize the creation of image signals. Substituting ∆(w) for ∆  in Eq. 
 E.: Experimental Design Stttdy of an Airborne Interferometer for Terrain Avoitiance,  !nt~r~~cttionul Cor!fc.rt~ncc R,4DAR-77, pp. 508 512. IEE (Idondon) Conf. 
 E. Brindly et al., “A Joint Army/Air Force investigation of reflection coefficient at C and Ku  bands for vertical, horizontal and circular system polarizations,” IIT Research Institute, Final  Rept., TR-76-67, AD-A031403, Chicago, IL, July 1976. 113. 
 62, pp. 673–680, June 1974. 79. 
 1967. 60.Ruze,J.,F.LSheftman, andD.A.Cahlander: RadarGround-Clutter Shields.Pmc.IEEE.vol.54. pp.1171-1183, September. 
 NIQUES SINCE THE PHENOMENON OCCURS NEAR THE GROUND AND OFTENTIMES IN VERY LIGHT OR NO PRECIPITATION # BAND IS THE PREFERRED  OPERATIONAL FREQUENCY FOR SEVERAL REASO NS &IRST  A # 
 MANCE OF MODERN OPERATIONAL WEATHER RADARS 4ABLE  CONTAINS SOME OF THE MORE RELEVANT ORIGINAL .EXRAD DESIGN FEATURES &IGURE  SHOWS A TYPICAL .EXRAD INSTALLATION AT -ISSOULA  -ONTANA 4HE ANTENNA IS  MOUNTED ON A TOWER TO CLEAR SURROUNDING OBSTACLES SUCH AS BUILDINGS AND TREES 4HE ELEC 
 33, no.  17. pp. 
 114. Webster. A. 
 Blackwell. F.. and E. 
 The underestimation of debiased-CS is mainly caused by the missed detections. Since there are some missed detections in the result of debiased-CS, the intensities of the debiased-CS is less than BP . CS causes bias and missed detections because of the regularizer term. 
 20. Morgan, S. P.: Some Examples of Generalized Cassegrainian and Gregorian Antennas, IEEE Trans.,  vol. 
 9.21. Radomes.1-It isnecessary toprotect allairborne and some surface-based microwave antennas from wind and weather. The pro- tective housings have come tobeknown as‘‘radomes.” Afuller discus- sion than thefollowing will befound inVol. 
 4.27. The input on the left is from  the out put of the I and Q A/0 converters. The three-pulse canceler and the eight-pulse doppler  filter-bank eliminate zero-velocity clutter and generate eight overlapping filters covering the  doppler interval, as described in the previous section. 
 12.8. Automatic gain control isnecessary toprevent strong signals from overloading the receiver, and toinsure that signals are applied tothedecoder atthecorrect level. Bandwidth varies with the particular characteristics oftheradar set and thetype ofsynchronization used. 
 The greater the  wrap-up factor, the less the frequency band required to steer the beam over a given angle;  however, the longer it will take to fill the array and the less will be the bandwidth that the array  can support. For example, if the array antenna had an - aperture of 5 m and if the wrap-up -  factor were 15, it would take 0.25 ~ts to fill the array. The pulse width should be long compared  to this time if distortion is not to result. 
 A. Weil, “Efficient spectrum control for pulsed radar transmitters,” Chap. 27 in Radar  Technology , E. 
 DOMAIN '02 SYSTEMS# $  %%#  %    '  %      
 Air Route Surveillance Radar) located at Canton,  Michigan. The target of interest is a small private aircraft. As the personal computer version of AREPS developed, it also transitioned into an  application called the Naval Integrated Tactical Environmental Subsystem (NITES), a  segment of the Global Command and Control System - Maritime (GCCS-M). 
 WASAR Subaperture Imaging Based on Compressed Sensing WASAR receives data from a large angle. The conﬁguration of WASAR is depicted in Figure 1. The whole aperture can be divided into subapertures. 
 ALARM RATES ARE SELECTED ON THE BASIS OF PERFORMANCE OF ELECTRONIC CIR 
 6.11. The elec­ tron optics is similar to the klystron. Both employ the principle of velocity modulation to  density-modulate the electron beam current. 
 BAND )-$ CAN OCCUR AT ANY STAGE THROUGH THE RECEIVER  AND HENCE EVEN SECOND 
 One important technique for im- proving the efficiency of high-power TWTs is called velocity tapering. This tech- nique consists of tapering the length of the last few circuit sections of the slow- wave circuit to take into account the slowing down of the beam as the energy is extracted from it. Velocity tapering permits extracting more of the energy from the beam and significantly improves the power-bandwidth performance of the tube.31 Nevertheless, high-power TWTs generally show an appreciable falloff of power output toward the band edges, so that the rated bandwidth depends very much on how much power falloff can be tolerated by the system. 
 ON 
 J. E. V older, “The CORDIC trigonometric computing technique,” IRE Trans. 
 15,  pp. 47–55, 1998. 118. 
 SPECIFIC LOSS ACCOUNTS FOR  THE LOSS IN GAIN WHEN TH E  TARGET IS NOT LOCATED AT THE PEAK OF THE BEAM "EAMSHAPE LOSS IS DEFINED AS THE INCREASE IN THE POWER OR THE 3.2 REQUIRED TO ACHIEVE THE SAME PROBABILITY OF DETECTION ON A TAR 
 ABLE LEVEL DEPENDS ON THE NATURE OF THE PROCESSING PERFORMED 3IGNAL 
 Theshort-pulse waveform alsocantolerate unknown shiftsinthedoppler frequency whenusingasinglematched filter.. Phase-coded pulse compression. ' 6-29.30s38 I n this form of pulse compression, a long pulse of  duration T is divided into N subpulses each of width r. 
 Skillman, “Master oscillator requirements for coherent radar sets,” in IEEE- NASA Symposium on Short Term Frequency Stability, NASA-SP-80, November 1964. 49. R. 
  AND + 
 TIONS  SO AS TO ALERT THE RADAR OPERATOR IF A DISCREPANCY EMERGES  WHICH MIGHT BE INDICA 
 A" typical" patch of the ground illuminated by a single frequency might be  about 1000 km in the range coordinate. The region from 1000 to 4000 km might therefore  require the radiation of three different frequencies for full coverage. On the other hand, there  might be times when ionospheric.conditions allow this region to be covered by only a single  frequency, while at other times five or six frequencies might be required. 
 TRAILER RESULTING FROM THE  PROCESSING 4HE TWO 
 BLE ACTIVITY AND ASSOCIATED SCINTILLATION IN EQUATORIAL REGIONS  SOLAR FLARES  AND CORONAL MASS EJECTIONS ALL OF WHICH DISRUPT STABLE PROPAGATION 3OLAR FLARES ARE GIANT EXPLOSIONS ON THE SUNS SURFACE  GENERALLY OCCURRING NEAR SUNSPOTS  WHICH EMIT IONIZING RADIATION THAT PENETRATES INTO THE $ REGION AND DRAMATICALLY INCREASES ABSORPTION 4HE RESULTING SUDDEN IONOSPHERIC DISTURBANCE  3)$  OR  SHORT 
 38, no. 3, pp. 1023–1037,  July 2002. 
 TER LOCATION %XTENDED VOLUME SEARCH IS A MODE USED WITH CUEING FROM ANOTHER ON 
 195-204, March, 1969.  56. Shrader, W. 
 TO 
 I>utton. and R. 11. 
 l dB.45  Zero-crossings detector. The information contained in the zero crossings of the received signal  can, in principle, be used for detecting the presence of signals in noise. The greater the  signal-to-noise ratio the less will be the average number of zero crossings. 
  OR CLOSED 
 20.9 NOISE, INTERFERENCE,   AND SPECTRUM OCCUPANCY In the HF band, the average noise power spectral density at mid-band, near 15 MHz,  say, may exceed –150 dBW/Hz and will generally exceed –175 dBW/Hz, compared  with typical receiver internal noise spectral densities of perhaps –195 dBW/Hz. Thus,  unlike the microwave radar case, external noise is almost always dominant. This has  fundamental implications for receiving system design and signal processing. 
 Assunling an array matched at broadside, resistive mismatch off  broadside results in 7 percent of-the power reflected at the maximum scan angle. The beam-  witlt h at the niaxi~iiutn scan angle is 1.75 tilnes that of the broadside beamwidth. The reduction  in gain is 2.8 rlB. 
  
 58. Sensors 2019 ,19, 213 T able 1. The complexity of the main steps of the EMAM method. 
 Owing to the finite number of filters imple- mented in the filter bank, the average SCR improvement will change by a small amount if a doppler shift is introduced into the clutter returns. This effect is illus- trated by the cross-hatched region, which shows upper and lower limits on the av- erage SCR improvement for all possible clutter doppler shifts. For a smaller number of filters in the doppler filter bank this variation would be larger. 
 Ó°Ó  2!$!2 (!.$"//+  TRANSMITTER HAS VERY LITTLE PULSE 
 FECT 4HIS  IN TURN  LEADS TO SYSTEM LIMITATIONS MORE SEVERE THAN PREDICTED HERE SEE 3ECTION  &)'52%  $IGITAL -4) CONSIDERATION 4!",%  4YPICAL ,IMITATION ON ) $UE TO !$ 1UANTIZATION .UMBER OF "ITS  . 
  
 ERROR INFORMATION ON ONE CHANNEL WITH RESPECT TO THE OTHER IS THAT SIGNAL AMPLITUDE FLUCTUATIONS IN THE RECEIVED SIGNAL ARE CANCELED IN THE POST 
 Zoughi, J. Bredow, and R. K. 
 They are epitomized by their superior short-range performance and by having a dis - play in “portrait” format in order to get maximum look-ahead along the waterway.  The maximum display range on the shortest scale is typically 150 meters. These  radars are normally designed to meet requirements for radars on vessels navigating  the River Rhine.14 Radars for the fishing and leisure markets are not covered by SOLAS. 
 Int. J. Remote Sens. 
 2.7 as a function of the signal-to-noise ratio with  the probability of a false alarm as a parameter.  06  0.5  0.'1  ~ 0 3  C).  0.2  0.1 Noise alone  o..._::::..J...~...1-...L.l<.JOO""-.LLL...l.:.&.L..C:,,..L._--L~  0 4 5 6 7 R/ffo-Figure 2.6 Probability-density function for noise alone  and for signal-plus-noise, illustrating the process of  threshold detection. 
 17 .16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 Synthetic Aperture Radar* Roger Sullivan Institute for Defense Analyses Most of the discussion in this Handbook concerns real aperture radar  (RAR) ,  where the antenna is a physical object that first emits, and then collects, the radia - tion. We turn our attention to the case where the antenna moves to cover a syn- thetic aperture , thus producing synthetic aperture radar  (SAR) . This overview is  based on Sullivan1 and Cutrona2†; more detailed treatments are also provided in  the literature.3–11 17.1 BASIC PRINCIPLE OF SAR For airborne or spaceborne ground-mapping radar, there has been continuous desire  to achieve finer resolution. 
 F. Barton, Artech House, Norwood, Mass., 1987. 8. 
 633. The principal operational limitation ofthis equipment was aresult ofthefact that very broad beams were produced bythesingle-dipole-and- reflector antennas used. These broad beams gave strong reflections from the ground beneath theaircraft, restricting the maximum range at which aircraft echoes could beseen toless than thealtitude atwhich the AI-equipped fighter was flying. 
 Assume that the transmitter frequency increases linearly with time, as shown by the solid line  in Fig. 3.10a. If there is a reflecting object at a distance R, an echo signal will return after a time  T = 2R/c. 
 D. Queen: Dynamic Measurement or Radar Cross Sections, Proc. IEEE, vol. 
 RANGE AIRCRAFT RETURNS 4HE 2ADAR 3YSTEM )MPROVEMENT 0ROGRAM 23)0  PROVIDES THE MOST SIGNIFICANT UPGRADE TO THE !7!#3 RADAR SINCE ITS DEVELOPMENT IN THE EARLY S 23)0 INTRODUCES NEW WAVEFORMS AND PROCESSING  PROVIDING IMPROVEMENTS IN DETECTION RANGE  ANGULAR ACCURACY  AS WELL AS RANGE AND ANGULAR RESOLUTION !.403 
 15.37  Improvement Factor Limitation Caused by  Staggering  .......................................................  15.39  Time-Varying Weights  ........................................  15.40 . 
 13.10] SAWTOOTH GE,VBliATOh?S 513 This method isused inthe precision delay circuit ofFig. 13.36, described inthenext section. 3.The most common method ofusing linear amplifier gain tokeep thenecessary signal voltage small isillustrated inthediagrams of Fig. 
 Section 12.2 summarizes the basic design principles and parameters governing reflec - tor antenna design. Section 12.3 provides a brief overview of conic sections and classes  of reflector systems and associated optics. Section 12.4 discusses various types of  reflector feeds and related design principles. 
 Unlike land clutter, storm clouds are not stationary and usually  have a nonzero relative velocity that results in a doppler-frequency shift. The internal motions  of the storm can also widen the spectrum of the precipitation clutter. At the higher microwave  frequencies, where precipitation can be a bother, it is difficult to achieve effective MTI because  of the reduced blind speeds (Sec. 
 IEE Proc. Radar Sonar Navig. 2005 ,152, 253–262. 
 1163–1175, October 2001.  3. M. 
 AIR )3!2 IS SHOWN IN &IGURE    &)'52%  .ONCOOPERATIVE TARGET RECOGNITION SUBMODES . 
 441–500, 1998. ch18.indd   65 12/19/07   5:15:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 MASKING EFFECTS . 
 137, Pt F, no. 2, April 1990. 30. 
 But  there it is; many of the circuits do appear revolutionary,  impracticable, and to the conventional radio man  ‘impossible.’  In the scope of this book it is obviously not possible  to deal with all radar circuits and manners of producing  square waves, pulses, and bursts of energy in various  time-forms. But if the reader has studied some reliable  work, such as C. L. 
 Hayes, and L. C. Bomar: mm-wave Reflectivity of Land and Sea, Microw,we J.,  vol. 
 Set the noise level (grass) to about one-third of full output using the gain knob. Figure 3.10. Antenna elevation beam pattern (1-way Gain) for ASV Mk. 
 37–41, March 1955. 14. G. 
 Tlie eclrn  signal will he niorlt~latcd at a frequency equal to ttie rotation frequency of the beam. ?'tie  ;tnll>litclde of ttic cclio-sigtial modulation will depend upon the shape of the antenna pattern,  111~' sqilil~t arigle. atid tlie ariglc between tlie target line ofsight and the rotation axis. 
 PICTURE ON THE TUBE  Range-amplitude display compared with the  split display—How persistence of vision  helps us to appreciate the picture on the tube  —A one-directional map given by an elemen-  tary CRT display—The graph representation  given by Type B—Type C display, giving  elevation-azimuth information—How a PPI  display is built up from radial spokes of the  rotation time-base.  CENTIMETRIC TECHNIQUE  How Watson-Watt foresaw the need for  centimetric wavelengths in radar—The men  who made the new technique possible—Revo-~  lutionary valves—How the magnetron, Kly-  stron, Sutton tube, and Heil tube work—  Spark-gap modulators—Why transit time  prevents the use of normal valves for centi-  metric radar—Superhet receiver circuits for  these extremely short wavelengths—A simple  explanation of wave-guides—The irony of a  return to crystal detectors and spark-gaps in  radar—Turning the clock back to 1914.  THe Task AHEAD  How the war-developed systems have been  harnessed for peacetime needs—Difference  between pulse and non-pulse radio navi-~  gational aids—-Gee and Console—The com-  mercial uses for H2S, Loran, and Oboe—  Description of a present-day marine radar  system—What the. 
 21.21  Effects of Motion Errors  .....................................  21.21  Multiple-Beam Radars  .......................................  21.21 ISAR  ................................................................. 
 The coherent length with different spectral index is illustrated in Figure 7, and the scintillation strength is set as CkL=1032 refers to the mildly scintillation condition. (a)( b) Figure 6. The comparison of TFTPCF curves between stripmap mode (red curves) and sliding spotlight mode (blue curves) with different CkL(real line: CkL=1032, dashed line: CkL=1033). 
 ANGLE TRACKING PROBLEM v PRESENTED AT  )%% )NT 2ADAR #ONF   ,ONDON    /CTOBER n    $ + "ARTON AND ( 2 7ARD   (ANDBOOK OF 2ADAR -EASUREMENT  %NGLEWOOD #LIFFS  .*  0RENTICE 
 12.29 shows an ear- lier summary based mostly on X-band data. One should be cautious in using this data, but the figure gives a feel for the overall variations. Figure 12.30 is a similar presentation for near-vertical data.93 Calibration of the systems was good, but the antenna effect discussed in Sec. 
 ANGLE  SOLUTION OF THE TWO 
 (FromDuley,et al.37). RADAR CLUlTER 493  -50  -60 - -. J 1- 1- i-l_l--A  1" 3" 5" 10" 30" 60" 90" , , , , , ,x,+j  Grozlng angle  (c) 10  0 -  3  g -10  0-  0) .. 
 TIONS LEAD TO TRANS 
 STATE PREAMPLIFIER 4HE KLYSTRON REQUIRES  K6  PROVIDED BY A HIGH 
 SURVEILLANCE RADAR ALSO OPERATES AT 3 BAND 5SUALLY  MOST RADAR APPLICATIONS ARE BEST OPERATED IN A PARTICULAR FREQUENCY BAND AT WHICH THE RADARS PERFORMANCE IS OPTIMUM (OWEVER  IN THE EXAMPLE OF AIRBORNE AIR 
 A. Fabrizio, G. J. 
 This situation should improve over  time as faster and faster processors become available. Custom-designed Hardware.  Through the 1990s, real-time radar DSP systems  were built using discrete logic. 
 Ward and W. W. Shrader, “MTI performance degradation caused by limiting,” in EASCON  ’68 Tech. 
 RadiaLion from the transmitting antenna floodlit aquarter-sphere infront ofthestation, the qreater part ofthe energy being confined within 20° ofthe horizontal and within approximate yt50° ofthe main “line ofshoot. ”Enough 1SirR.A.Watson-Watt, “Radar inWar andinPeace,” Nature, 166, 319-324, (1945).. SEC. 
 Point scatterer image, contour plot, and range and azimuth cuts. 98. Sensors 2019 ,19, 1649 3.3.1. 
 Sens. , vol. GE-26, pp. 
 Klauder, A. C. Price, S. 
 AblockdiagramofanMTIradar(withapoweroscillator) isshowninFig.4.6.Aportion ofthetransmitted signalismixedwiththestaloo!JtputtoproduceanIFbeatsignalwhose phaseisdirectly related tothephaseofthetransmitter. ThisIFpulseisappliedtothecoho andcausesthephaseofthecohoCWoscillation to"lock"instepwiththephaseoftheIF reference pulse.Thephaseofthecohoisthenrelatedtothephaseofthetransmitted pulseand maybeusedasthereference signalforechoesreceivedfromthatparticular transmitted pulse. Uponthenexttransmission anotherIFlockingpulseisgenerated torelockthephaseofthe CWcohountilthenextlockingpulsecomesalong.ThetypeofMTIradarillustrated in Fig.4.6hashadwideapplication. 
 Long, “Improved resolution backscatter measurements with the  SeaWinds pencil-beam scatterometer,” IEEE Transactions on Geoscience and Remote Sensing ,  vol. 38, pp. 89–104, 2000. 
 CAL BEAMWIDTH  IN DEGREES 4HUS  FOR EXAMPLE   R VS OF RAIN VIEWED AT  NMI WITH A  VERTICAL BEAMWIDTH OF  WOULD BE  R VS    MS  4HE TOTAL SPECTRAL SPREAD IS THEN  SS SV       VT VSMS       2AIN AND CHAFF ALSO HAVE AN AVERAGE VELOC 
 17.2 can beused forthis purpose. If,on theother hand, themodulator isself-synchronous, itspulse must beused totrigger the coder. The synchronizing pulse atthe receiving station, which must await the arrival ofthe third pulse, will be6~sec late. 
 The straight line is the original Phillips saturation asymptote, which is approached  at high frequencies in this example. The scale marked “wind velocity” can be used to deduce that winds up  to 40 kt have excited waves with frequencies as low as 0.08 Hz, but that either the duration or fetch, or both,  have not been sufficient for full development. The scale across the top gives the radar frequency correspond - ing to resonant backscatter. 
 STEERING ALGORITHM BASED ON OUTPUT POWER MEASUREMENTS v  )%%%  4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS  VOL   NO   PP n  *ULY . x°{{  2!$!2 (!.$"//+   ( 7ANG  ( 0ARK  AND - 7ICKS  h2ECENT RESULTS IN SPACE 
 The radar designer, inother words, cannot adjust pulse duration arbitrarily, keeping average power constant; nor can the receiver pass band bemade arbitrarily narrow as~isincreased, foreffects such asfluctuations ofthe echo eventually impose alimit. This problem will bediscussed indetail inthefollowing chapter which isconcerned specifically with c-w radar. The general conclusion, however, remains valid—an essential advantage ofhigh pulse power, asused inpulse radar, isthat itpermits information tobe obtained rapidly. 
 13.72  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 42. A. Ksienski, “Equivalence between continuous and discrete radiating arrays,” Can. 
 Radar Absorbers.  The purpose of the radar absorber is to attenuate incident  energy and thereby reduce the energy scattered or reflected back to the radar. Most  absorbers are designed to reduce specular reflections from metallic surfaces, but stealth  technology has spawned the development of nonspecular absorbers intended primarily  to suppress echoes due to surface traveling waves. 
 GUITY  IS EXTENDED TO ALLOW ONE VELOCITY AMBIGUITY  THAT OF DOPPLER SENSE 4HE LOWER 02& EASES THE MEASUREMENT OF TRUE RANGE WHILE RETAINING THE HIGH 
 Achange 68. in 4 with rcspcct to time is equal to a frequency. This is the doppler angular frequency wd. 
 FIGURE   9.8  Five-horn feed with coupling to both linear-polarization components, which are  combined by the switch matrix to select horizontal, vertical, or circular polarization ch09.indd   9 12/15/07   6:07:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 
 SHAPED  CLUTTER SPECTRUM WE HAVE   3F 0FF ## FD F  E X P    
 The delay time can be varid  by changing either the number of stages (a capacitive storage element and its associated  switch) or by changing the switching frequency controlled by a digital clock. CCDs provide a  similar function except that charge packets are transferred to adjacent potential wells by  clocked voltage gradients. The sampling frequency must be such as to obtain one or two  samples per range resolution cell. 
 When the antenna designer is  restricted by the nature of the application, large isolations may not be possible. For example,  typical isolations. between transmitting and receiving antennas on missiles might be about  50 dB at X band, 70 dB at K band and as low as 20 dB at L band.9 Metallic baffles, as well as  absorbing material, placed between the antennas can provide additional isolation. 
 ROCAL MIXING ARE STILL PRESENT  THOUGH IN SLIGHTLY MODIFIED FORM #OMPARISONS WITH ANALOG RECEIVERS HAVE DEMONSTRATED THAT LITTLE OR NO PENALTY IS INCURRED WITH SUCH DESIGNS IF A BAND PRESELECTOR FILTER IS INSTALLED AT THE FRONT 
 We seethat shorter wave- lengths make possible sharper beams; this accounts forthe very con- 1Forafuller account ofradar scanners thereader isreferred toRadar Scanners cniRadornes, Vol. 26ofthisseries. 2Sees. 
 ,Ê / 
 The most  remote point of illumination is controlled, so that the  H2S can scan over, say, ranges of 50 miles, 20 miles,  and 5 miles, and at each setting a full-diameter circle ts  displayed on the CRT. Obviously a PRF of over 500  must be used for such equipments, and the scanner is  rotated at a speed seldom in excess of 1} revolutions 2  second. The effective angle of inclination of the scanner  . 
 32) and isgiven by (25) where aisthe radius o’fthe raindrops, dtheir diameter, and the bar denotes averaging over alldrops that contribute tothe return. Since ueither Knorthe distribution indrop size isvery ~vell known, itwill not bepossible totest this formula experimentally with great precision, but theexisting measurements ofaverage intensity can beexplained, assum- ingreasonable values ofNand =6. Using Eq. 
 Mission  management must cope with data collection in each of these modes, as well as phas - ing the resulting data burden to share the communications link with the two other high  data-rate instruments in the ALOS payload. The standard policy for the early years of  PALSAR’s on-orbit scheduling is to focus on six “default” modes—four “operational”  and two “semi-operational.” The resulting terms are (1) fixed “standard” off-nadir  angle of 41.5 ° for a great majority of the data takes; (2) polarization options to be  single-pol HH and dual-pol HH +HV; (3) quad-pol at 21.5 ° (off-nadir) for R&D dem - onstrations over preselected “supersites”; and (4) five-beam ScanSAR in HH polariza - tion. In addition, the following constraints apply: only one mode is exercised during  one 46-day repeat cycle; preferred operations are during the hours of darkness in the  ascending passes for most modes, excepting lower data-rate ScanSAR data takes dur - ing descending passes (in coordination with the optical sensors) and also excepting  extraordinary InSAR and marine applications at nonstandard incidence; and recurrent  repeat-pass coverage of selected sites in groups of eight or more 46-day cycles in sup - port of InSAR objectives. 
                  
 SEC. 3.4] APPROXIMATIONS FORLARGE METAL TARGETS 65 3.1, where aistheradius ofthesphere and Xtheradar wavelength. For wavelengths large compared totheradius, the cross section isgiven by Rayleigh’s law. 
 Returning toFig. 10.1 itisseen that the side cavities open atboth ends into chambers, orend spaces. These end spaces assist incoupling theseparate oscillators byallowing magnetic flux topass from one oscil- lator into the next. 
 Thus pulse-to-pulse frequency changrs  (Irequcncy agility) of I/r or greater will decorrelate the clutter and permit an increase in  target-to-clutter ratio when the decorrelated pulses are integrated. With a high-resolution  radar in which the persistent sea-clutter spikes appear, the benefit of frequency agility is  decreased since the sea spikes are correlated over a relatively long period of time and appear  sirnilar to target echoes. Thils frequency agility will be of less value the more non-Rayleigh the  clutter statistics. 
 each of the principal planes. The penalty they incur for placing a thick (0.4X) and potentially heavy dielectric slab in front of the aperture is mitigated by the low dielectric constant of the slab (e,. = 1.3). 
 In this radar the STC is applied in the RF ahead of the  low-noise amplifier. The advantage of STC in the RF as compared to the IF is that it prevents  saturation of the RF amplifier, as well as the IF amplifier, by close-in clutter. Themoist: level in  the receiver is but little affected by the STC, a condition that is desired for operation of the  log-CFAR receiver. 
 DAY VARIABILITY  EVEN AT MID 
 The stochastic  constraints adaptive beamforming and STAP methods181–184 were developed specifi - cally for the HF environment to address the rejection of nonstationary interference  while protecting the clutter doppler spectrum properties. A method for time-varying  spatial adaptive processing (TV-SAP)185 that addresses the same problem was found to  be more attractive for practical implementation due to the much lower computational  cost in real-time applications, as well as greater robustness in protecting sub-clutter  visibility after doppler processing. The problem of reducing false alarms caused by  strong sidelobe targets and spatially structured (non-gaussian distributed) RFI was  treated in Fabrizio et al.,186 where the advantages of adaptive subspace detectors rela - tive to conventional approaches were shown. 
 Theconstruction ofalargeButlernetwork requires alargenumber of cross-over connections inthetransmission lines.Thesecanpresentpractical difficulties inthe fabrication ofthemicrowave printedcircuitsusedtomakeupthedevice.20Manybeamsalso requiremanyparallelreceivers, anaddedcomplexity. Forthesereasons,Butlerbeam-forming networks withlargenumbers ofelements arenotthegeneralrule. hispossibletoconstruct planararrayswithButlernetworks. 
 BANDWIDTH  THE MAGNITUDE OF THE AUTOCORRELATION FUNCTION  MEASURED ALONG THE RELATIVE TIME DELAY AXIS IS GIVEN BY   \     \CT T TU "4y   \SINC  \  \ \   4HE X 
 TIME FREQUENCY PLANE ! MAIN 
 USED TERMS AS  "RAGG WAVELETS  "RAGG  PATCHES  AND SO ON  AS IF SUCH THINGS HAD A REAL EXISTENCE OUTSIDE OF THEIR EMERGENCE  AS AN ARTIFACT OF A FILTER OPERATION 4HIS CONFUSION OF CONCEPTS MIGHT BE AVOIDED BY VISUALIZING THE RADAR AS EXTRACTING THE h"RAGG LINEv FROM THE SPECTRAL COMPOSITIONS OF THOSE SURFACE FEATURES THAT CONTAIN A WAVE OF LENGTH  K COSX  IN THEIR &OURIER  REPRE 
 QUENCIES AND THE ACCURATE MEASUREMENT OF TARGET LOCATION IS BETTER PERFORMED AT HIGH FREQUENCIES )F ONLY A SINGLE RADAR OPERATING WITHIN A SINGLE FREQUENCY BAND CAN BE USED  THEN 3 BAND IS A GOOD COMPROMISE )T IS ALSO SOMETIMES ACCEPTABLE TO USE # BAND AS THE CHOICE FOR A RADAR THAT PERFORMS BOTH FUNCTIONS 4HE !7!#3 AIRBORNE AIR 
 For example, some roads cannot support high speeds and tanks  do not have to be on roads. A common SAR-MTI display may be presented to the operator. In addition, guid - ance commands or errors are derived from the measurements and provided to down - links to either missiles on the fly or gun directing computers for the next rounds. 
 )          &)'52%  $UCTING CONSEQUENCES.   4(% 02/0!'!4)/. &!#4/2  &0  ). 4(% 2!$!2 %15!4)/.   ÓÈ° $UCTS NOT ONLY GIVE EXTENDED RADAR DETECTION RANGES FOR SYSTEMS WITHIN THE DUCT   BUT THEY MAY ALSO HAVE A DRAMATIC EFFECT UPON TRANSMITTERRECEIVER SYSTEMS THAT TRAN 
 43.Muehe. C.E.:Advances inRadarSignalProcessing, IEEEElectro'76,Boston, Mass,May11-14, 1976. 44.Drury.W.H.:Improved MTlRadarSignalProcessor. 
 2.82  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 When doppler shifts are introduced by digital means as described above, the accu - racy of the I and Q representation of the original input data becomes an important  consideration. Any dc offset, amplitude imbalance, quadrature phase error, or nonlin - earity will result in the generation of undesired sidebands that will appear as residue  at the canceler output. A discussion of A/D conversion considerations was presented  in Section 2.13. 
 Thus the added complexity of higher-order cancelers is seldom justified in such  situations. The linear analysis of MTI signal processors is therefore not adequate when limit­ ing,is employed and can lead to disappointing differences between theory and measurement of  actual systems.  Limiters need not be used if the MTI is linear over the entire range of clutter signals and if  the processor has sufficient improvement factor to reduce the largest clutter to tre noise level. 
 (ILL     ' 7 3TIMSON   )NTRODUCTION TO !IRBORNE 2ADAR   #HAPTER   0ART 8  ND %D  2ALEIGH  .#  3CI4ECH 0UBLISHING  )NC  . 
 Dept. Commerce P~tbl. 62-1, 1959. 
 III A number of improvements and upgrades were made to H 2S Mk. II, including a roll stabilised scanner and a scan-corrected PPI (showing ground range) on H 2S Mk. IIC, but these were not incorporated in ASV Mk. 
 BASED DUCTS MAY EXTEND OVER THE OCEAN FOR SEVERAL HUNDRED KILOMETERS AND MAY BE VERY PERSISTENT LASTING FOR DAYS  !NOTHER METHOD OF PRODUCING SURFACE 
 MODE      4WO 
 Farnett, RCA Electronics Systems Department, GE Aerospace (CHAPTER 10) Joe Frank, Technology Service Corporation (CHAPTER 7) V. Gregers-Hansen, Equipment Division, Raytheon Company (CHAPTER 15) J. M. 
 [Equation (7.10) appliestoaone-dimensional linesourcelyingalongtill:zaxis.Fortill:two-uiml:llsional aperture ofFig.7.2,A(z)istheintegralofA(x,z)overthevariablex.] Equation (7.10)represents thesummation, orintegration, oftheindiviuualcontributions fromthecurrentdistribution acrosstheaperture according toHuygclls' principle. Atanangle ¢,thecontribution fromaparticular pointontheaperture willbeadvanced orretarded in phaseby21£(zI1)sin¢radians.Eachofthesecontributions isweighted bythefactorA(z).The fieldintensity istheintegraloftheseindividual contributions acrossthefaceoftheaperture. Theaperture distribution hasbeendefinedintermsofthecurrentix.Itmayalsobe definedintermsofthemagnetic fieldcomponent Hzforpolarization inthexdirection, orin termsoftheelectricfieldcomponent Ezforpolarization inthezdirection, provided thesefield components areconfined totheaperture.? Theexpression fortheelectricfieldintensity [Eq.(7.10)]ismathematically s.i]nilartothe inverseFouriertransform. 
 °{{  2!$!2 (!.$"//+  DISTRIBUTION CHANGES SHAPE  BECOMING SOMEWHAT RECTANGULAR WITH A SEPARATION OF  AIRCRAFT AS IN &IGURE  B !T THE WIDEST SEPARATION  WHERE THE AIRCRAFT ARE ALMOST  RESOLVED  AS IN &IGURE  C  THE RADAR WILL TRACK ONE AIRCRAFT UNTIL IT FADES AND THE  OTHER AIRCRAFT BLOSSOMS IN AMPLITUDE 4HEN THE RADAR 
 A typical example of a GPR image is shown in Figure 21.29 with the  various features identified. GPR has significantly improved the efficiency of the exploratory work that is fun - damental to the construction and civil engineering industries, the police and forensic  sectors, security/intelligence forces, and archaeological surveys. GPR has been very successfully used in forensic investigations. 
   2!$!2 2%#%)6%23   È°x£ , 
 antenna was toolarge tobetolerated fortheAN/APS-10. Experiments showed that an18-in. cosecant-squared antenna designed foranaltitude of7000 ftwould beuseful intheusual altitude range from 1000 to10,000 ft without unduly overilluminating short-range targets atlow altitude or causing tooserious ahole inthecenter ofthepattern ataltitudes higher than 7000 ft. 
 120, pp. 833-842, August 1973. 121. 
 Figure 11.10 is  an example of the two-dimensional plot of the three-dimensional ambiguity diagram corre-  sponding to the single pulse of Fig. 11.9~. Shading is used to give an indication of the regions  in which Jx(T,, &)I2 is large (completely shaded areas), regions where Izl2 is small but not  zero (lightly shaded areas), and regions where I x IZ is zero (no shading). 
 21, pp. 148-151, 1966.  117. 
 4.16, the blind speeds are coincident for 4/T1 = 5/T2•  Although the first blind speed may be extended by using more than one prf, regions of low  sensitivity might appear within the composite passband.  The closer the ratio T1 : T2 approaches unity, the greater will be the value of the first blind  speed. However, the first null in the vicinity of fd = 1/T1 becomes deeper. 
 6 Unperturbed field and field including feed blockage −60−50−40−30−20−100 0 5 10 15 20 AngledBBlocked Unperturbed FIGURE 12. 7 Unperturbed pattern and pattern including blockage ch12.indd   10 12/17/07   2:31:12 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Thus, the overall model seems  representative of summer conditions averaged over all of North America. The model takes the form  σ θ θ θ θdB020 70 ( ,)f A B C f D f = + + + ° ≤ ≤ °  (16.24 a) where A, B, C, and D take on different values for different polarizations above and below  6 GHz. The frequency response below 6 GHz is much more rapid than above 6 GHz. 
 AVUAVIE  GINEIVIN,  CAL  CLLV'  Id  . Orr  frog1  *  ‘xipuaddy  97g] PILIISIA  JYdIALGor  wnoséy  dpddus  fo  Kaysiurpy  ayy  fo  Asaanoa  gq Uvava  axO  HO  NOILVUAdO  :A  ALV  Id  , Dee ste ine at ae.  . 
 The better appearance on the focused image is due to the normalization process. The images have been normalized with the same algorithm that ampliﬁes the focused revealed image to a ﬁxed value after normalization to the standard deviation of the whole image. The appearance of the image brightness is different because of the circular convolution in the Range Doppler procedure due to the frequency domain processing (its effect can be noted on the horizontal axis due to the presence of a periodic structure in the image that folds around the image). 
 3ECTION -EASUREMENTS  ND %D  . # #URRIE ED   .ORWOOD  -! !RTECH (OUSE   & 4 5LABY  4 % 6AN $EVENTER  * 2 %AST  4 & (ADDOCK  AND - % #OLUZZI  h-ILLIMETER 
 Delving deep into rectiﬁers: Surpassing human-level performance on imagenet classiﬁcation. In Proceedings of the IEEE International Conference on Computer Vision, Santiago, Chile, 11–18 December 2015; pp. 1026–1034. 
   4(% 2!$!2 42!.3-)44%2   £ä° THAT OF THE KLYSTRON  AND THEY BOTH USE THE PROCESS OF VELOCITY MODULATION TO CAUSE THE  ELECTRON BEAM TO BE PERIODICALLY BUNCHED DENSITY MODULATION  4HE ELECTRON BEAM PASSES THROUGH THE 2& INTERACTION CIRCUIT )N THE EXAMPLE SHOWN IN &IGURE   WHERE A HELIX IS SHOWN AS THE SLOW 
 The error signal may be recovered from the AGC  voltage with a narrow bandpass filter centered at the scan-modulation frequency.  Squint angle, The angle-error-signal voltage is shown in Fig. 5.6 as a function of Or, the  angle between the axis of rotation and the direction to the target.'' The squint angle 0, is the  158INTRODUCTION TORADAR SYSTEMS feedback signalandthegreaterwillbethegainreduction. 
 Conf. HF Radio Systems and Techniques , IEE Conference Publication no. 474, Guildford,  UK, July 2000, pp. 
 For a specific range, optimum frequencies vary by 3:1. Several qualifiers should be kept in mind. At other geographic locations, the ap- propriate CCIR noise should be selected or, better yet, measured noise used. 
 VERT AN ANALOG )& SIGNAL INTO A CORRESPONDING DIGITAL COMPLEX REPRESENTATION  RATHER THAN GOING THROUGH THE INTERMEDIATE STEP OF FIRST DOWNCONVERTING THE )& SIGNAL INTO BASEBAND IN 
 To further analyze the imaging results, Figure 9shows the same zoomed in patch of Figure 8.    (a) ( b)     (c) ( d)  Figure 8. Imaging fan results; ( a) FFT algorithm with 128 pulses; ( b) Relax algorithm with 128 pulses; (c) APES algorithm with 128 pulses; ( d) KA-DBS algorithm with 128 pulses. 
  +1 
 It is a surprise to many radar engi - neers that components of the radar receiver can cause degradation of the radiated  transmitter spectrum, generating harmonics of the carrier frequency or spurious dop - pler spectra, both of which are often required to be 50 dB or more below the carrier.  Harmonics can create interference in other electronic equipment. Spurious doppler  spectra levels are dictated by requirements to suppress clutter interference through  doppler filtering. 
 The received-echo-signal power is  considcrahly smaller than the transmitter power; it might be as little as 10-18 that of the  transmitted power-sometimes even less. Separate antennas for transmission and reception  help segregate the weak echo from the strong leakage signal, but the isolation is usually not  sufficient. A feasible technique for separating the received signal from the transmitted signal  when there is relative motion between radar and target is based on recognizing the change in  the echo-signal frequency caused by the doppler effect. 
 !RRAY , 
 Morris et al., “Principles of electronic counter-countermeasures,” short lecture notes,  Georgia Institute of Technology, 1999. 29. L. 
 Wehner, High Resolution Radar , Chap 4. 17. Galati, Advanced Radar Techniques and Systems , IEE Radar Sonar Navigation and Avionics  Series V ol. 
 Over anangular region inelevation where reflected intensity equals direct intensity, R~,,atthe center ofaninterference lobe isdoubled, but midway between two lobes R~.X =O. Atlong wavelengths (one meter orgreater), the use ofreflected radiation reduces requirements onantenna size, but the nulls. 604 5.EXAMPLES OFRADAR SYSTEM DESIGN [SEC.15.9 between lobes and especially thenull region below thelowest lobe aresufficiently broad tohandicap detection and tracking greatly. 
 DELAY CANCELLATION INCREASES AS A FUNCTION OF THE NUMBER OF HITS AT  D"DECADE FOR THE FIRST 
 PULSE DOPPLER RADAR  4.416x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 when the receiver is blanked during pulse transmission. In a multiple range gate sys - tem, the returns may also straddle gates reducing the pulse matched filter output of  a single gate. Because of eclipsing and range gate straddle, the value of Ro, given by  Eq. 
 BEAM RESOLUTIONS 4HE SHORTER WAVELENGTH + U 
 Electrons emitted by the cathode or the traveling­ wave tube are focused into a beam and pass through the RF interaction circuit known as the  slow-wave structure, or periodic delay line. An axial magnetic field is provided to maintain the  electron-beam focus, just as in the klystron. A shadow grid to pulse-modulate the beam can  also be included. 
 8 to 14.9 of an ogive, 14.7 to 14.8 prediction techniques, 14.16 to 14.27 of ships, 14.13 to 14.15 of a short wire dipole, 14.7 of a sphere, 14.5 to 14.6 of string, 14.6, 14.7,  14.29 and surface traveling waves, 14.7 of target support, 14.29 to 14.30 doppler shift in, 1.10 echo suppression, 14.36 to 14.43 in A-12, 14.40 in B-2, 14.42 in F-117, 14.40 to 14.42 in SR-71, 14.39 to 14.41 in X-45C, 14.42 to 14.43 by absorbers, 14.36 to 14.38.     I_13 by shaping, 14.36, 14.38 to 14.39 in ships, 14.42 to 14.43 equation, 1.10 to 1.13 bistatic, 23.4 to 23.6 and chaff, 24.55 to 24.56 in conceptual design, 1. 23 ground penetrating radar, 21.8 to 21.9 HF over-the-horizon, 20.5 to 20.7 and jamming, 24.55 for meteorological targets, 19.3 to 19.6 surveillance, 3.1 frequency bands, 1. 
 /. RESISTANCE OF THE &%4 IS KEPT AS HIGH AS  POSSIBLE 4HE CHANNEL LENGTH LARGELY DETERMINES THE /. RESISTANCE AND HENCE THE INSER 
 Any use is subject to the Terms of Use as given at the website. Sea Clutter. 15.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 In comparing statistical results, it should be kept in mind that to the extent that  the sea surface may be viewed as a stationary homogeneous process, as it generally  is over the duration and spatial extent of any particular experimental event, the scat - tering cross section may be said to be ergodic , which means that the statistical results  obtained by time averaging from a small cell are equivalent to an ensemble average  from a larger cell, provided that the number of “samples” is the same in the two  cases.43 For this reason, the statistical implications of experimental data can be prop - erly compared only if the details of the sampling procedure are specified. However,  the number of samples in most of the experimental results shown thus far have been  sufficiently large that the differences between, for example, Figures 15.2 and 15.12,  may be considered real and related to differences in grazing angle rather than in reso - lution cell size. 
 D. C. Schleher, MTI and Pulsed Doppler Radar , Artech House, Inc., 1991, pp. 
 Useful power isdelivered toanexternal load through acoaxial line, loop-coupled tothe cavity. The efficiency israther low, inthe neighborhood of1percent. Power outputs of20to50mw aretypical. 
 DolphBOderived thcaperturc illumination withthispropcrty byforcingacorrespondence between theChebyshev poly­ nomialandthepolynomial describing thepatternofanarrayantenna. Although aradiation patternwiththenarrowest bcamwidth foragivensidelobe levelseemsareasonable choicefor radar,itisseldomcmployed sinceitcannotbereadilyachieved withpractical antennas where highgainandlowsidelobes aredesired. Astheantenna sizeincreases, thecurrents attheend oftheaperture bccome largecompared withthecurrents alongtherestoftheaperture, andthe radiation patternbecomes sensitive totheedgeexcitation. 
 Pratt, Digital Image Processing , New York: Wiley & Sons, 1978, pp. 662–707. 78. 
 DUCED BY -ITZNER   AND THE SUMMATION OF THE FIELDS DIFFRACTED BY THE EDGE ELEMENTS  IMPLIES AN INTEGRAL AROUND THE EDGE CONTOUR -ITZNER  HOWEVER  SOUGHT THE FIELDS SCATTERED IN ARBITRARY DIRECTIONS  NOT JUST THOSE  ALONG THE LOCAL +ELLER CONES  AND FOR THIS PURPOSE HE DEVELOPED HIS  INCREMENTAL LENGTH  DIFFRACTION COEFFICIENT  ),$#  %XTENDING THE EXAMPLE PROVIDED BY 5FIMTSEV  HE  DEVISED A SET OF DIFFRACTION COEFFICIENTS FOR ARBITRARY DIRECTIONS OF INCIDENCE AND SCAT 
 The lengths of each toroid are selected to provide a differential phase  shift of 180°, 90°, 45°, 22.5°, and so forth, depending on the number of bit<-required. A separate  pair of drive wires is used for each section of toroid. Impedance matching is provided at the  input and output toroids. 
 6.29. The radar receiver israpidly s\vitched from thelefttotheright mem- 1B.vL.N.Ridenour.. SEC. 
 Its advatltagc is that it has truc  time delay, allowing a wide instantaneous bandwidth.  The ~ubis"~ antenna, which uses a parallel-plate lens, and the Bo~tlace'~' antenna,  which is a form of lens array, are also capable of RF beam forming. As mentioned, the  Li~neburg lens can be used as a beam-forming network to form multiple beams in conjunction  with a circular or spherical array,lo8 or the lens can be used directly to generate multiple  beams. 
 Combinations of semiactive or active radar with IR or ARH modes and the trend for operation at higher frequencies offer a large number of potential multimode seeker configurations. 19.4 SYSTEMFUNCTIONALOPERATION There are a number of necessary functions all of which must be successfully ac- complished to permit a lethal intercept of the target by a guided missile. These begin with initial target detection and decision to engage and include missile launch, proper operation of the propulsion, guidance, and control systems through the flight, and fuzing and detonation of the warhead at intercept. 
 The approximate range rate for each scat - terer in rolling (pitch, yaw) motion at a height, h, is the time derivative of R shown in  Figure 5.29. For a given desired cross range resolution with reasonable sidelobes, ∆rc,  b must be equal to ∆rc /l. For the example, 5 ft cross range resolution is obtainable  with a 10-second observation time. 
 The probability of detection probably depends not only on the signal-to-noise ratio in relation to the threshold but on the observer's visual-mental acuity, alertness or fatigue, DETECTABILITY FACTOR D0 (DECIBELS) . and experience. Consequently, curves calculated for an automatic threshold de- cision device cannot be assumed to apply accurately to the performance of a hu- man observer of a cathode-ray-tube display. 
 TIONS CAN SHOW DIFFERENCES OF ORDERS OF MAGNITUDE IN THE DENSITY OF CLUTTER DETECTIONS THAT CAN BE HANDLED  .EW 4RACK &ORMATION  4HERE ARE TWO CLASSES OF TRACK FORMATION ALGORITHMS   &ORWARD 
 The compressed pulse response at the output of the weighting filter is given by  y t Bt F B t m Bto m mn ( ) [ = + + + =− ∑ sinc( ) sinc( ) sinc( 11 − −m)] (8.11) As discussed below, the compressed pulse response (Eq. 8.11) is based on the assump - tion that the time-bandwidth product of the LFM waveform is much greater than unity  (TB  1). The filter matching loss for Taylor weighting is given by Klauder et al.1 as  L Fm m mn = + =− ∑ 1 22 11  (8.12) Figure 8.5 shows a comparison of the compressed pulse response for three fre - quency domain weighting types: Curve A is for uniform weighting where W(  f  ) = 1  FIGURE   8. 
 The mag­ nitude of the resulting height error is also dependent on  wave height, which, in turn, affects the slope of the fast­ rising leading edge of the signal. The indicated wave  height will also change slightly with attitude, and the am­ plitude of the reflected signal will decrease as the anten­ na beam departs from nadir pointing.  The correction processes begin with the computation  of a voltage proportional to attitude (V A TT) based on  the amplitude of the last eight waveform samples. 
 62.Koch,W.E.,J.L.Stone,J.E.Clark.andW.D.Friedle: Forward ScatterofElectromagnetic Wavl:s bySpheres. IREWESCONCQrW.RecD/'d,vol.2,pt.I.p.86,1958. 63.Kock,W.E.:Related Experiments withSoundWavesandElectromagnetic Waves. 
 SCAN BEAM 4HE JAMMER THEN HAS NO KNOWLEDGE OF THE PHASE OF THE CONI 
 Other subjects that are new or which have seen significant  changes in the current edition include low-angle tracking," on-axis" tracking, solid-state RF  sources, the mirror-scan antenna, antenna stabilization, computer control of phased arrays,  ,olid-state duplexers, CF AR, pulse compression, target classification, synthetic-aperture radar,  over-the-horizon radar, air-surveillance radar, height-finder and 30 radar, and ECCM. The  bistatic radar and millimeter-wave radar are also included even though their applications have . X PREFACE  been limited. 
 Figure 2.53 d shows the composite response of the filter bank. Note that the filter  peaks are fairly evenly distributed. The dip between the first zero-doppler filter and  the first moving doppler filter is larger than the others, primarily because, under the  constraints, it is impossible to move the first doppler filter nearer to zero velocity . 
 The referenced study showed that interpretability depends on  V; so tradeoffs between the three elements of V are possible. Best results for a human  interpreter occur when three independent samples of the fading are averaged. Ignoring  this fading (speckle) can lead to erroneous conclusions on the spatial resolution needed  for a given application. 
 W., and E. J. Weldon, Jr.: "Error Correcting Codes," app. 
 just as was the input. Before bipolar video can intensity-modulate a PPI display, it must  he converted to unipotcntial voltages (unipolar video) by a full-wave rectifier.  The simple MTI radar shown in Fig. 
 W. Burlage: An Initialization Technique for Improved MTI Performance in Phased Array Radar, Proc. IEEE, vol. 
 Appl. Earth Obs. Remote Sens. 
 Butement had been working on radar to locate ships as  targets for coast-defence artillery, and had made very  great progress in systems which are now not difficult to  adapt to the needs of peacetime shipping. At the same  time Mr P. E. 
 The advantage of using two prf's to detect targets in rain is illustrated by Fig. 4.28. Tile  prf's differ by about 20 percent. 
 47. Hartley-Smith, A.: The Design and Performance of a Modern Surveillance Radar System, IEEE 1975  International Radar Cot!fPrrnce, Arlington, Va.. Apr. 
 The size of the scene is 20 km ×20 km, and the platform and radar parameters are given in Table 2. The hydrodynamic parameter αandΓ0/υwas set to be−0.001486 and 10 π, respectively. The wind speed was 5 m/s, and the wind direction was 225◦. 
 The conical­ scan modulation is extracted from the echo signal and applied to a servo-control system which  continually positions the antenna on the target. (Note that two servos are required because  the tracking problem is two-dimensional. Both the rectangular (az-el) and polar tracking  coordinates may be used.] When the antenna is on target, as in B of Fig. 
 13 of" Radar Handbook," M. I. Skolnik (ed.). 
 RANGE G EOPHYSICAL APPLICATIONS  WHERE THE TARGET IS MANY TENS OF METERS FROM THE RADAR -ANY '02 RECEIVERS WERE ORIGINALLY BASED ON SAMPLING OSCILLOSCOPE TECHNOL 
 £n°£È  2!$!2 (!.$"//+  -ODERN SPACE 
  r . - # r F¼$  .  -    .   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/. 
 TION PERFORMANCE IS REQUIRED FOR A SPECIFIC MONTH OF THE YEAR AND A PARTICULAR SUNSPOT NUMBER OR YEAR OF SOLAR CYCLE !NALYSIS IS INITIATED BY SELECTING FROM THE DATABASE A MONTH THAT MATCHES THE  REQUIREMENTS )NDIVIDUAL BACKSCATTER IONOGRAMS ARE PAIRED WITH  THE CONCURRENT BACK 
 JR.J9AsthedutycycleofanFMpulsecompression waveform in­ creasesitbecomes moreliketheFM-CW waveform ofunitydutycycle.Hence.theprocessing Q) D .2 0. E <1 Distance FiJ!ure ~.18PlotofJ,(f))asafUllction ofdistallce. (FromSallllders.9IRETrails.). 
 RESOLUTION 8 
 LOSS AND INEXPENSIVE REACTIVE IMPEDANCE 
 THE 
 This has been called RADAR C not quite correctly, but it is a lineal descendant of RADAR C. NRL Memorandum Report 250052 describes the basic technique that will be used for path determinations. A simple closed-form virtual path trace, Snell's law for a spherically symmetric medium, is sequenced through elevation radiation an- gles in 1° increments. 
 OF 
 General Methods ofScanner-data Transmission.-Simultane- ous transmission ofvideo signals and range and angle markers isrela- tively simple. Marker signals need only bemixed with the video signals; noseparation isperformed atthe receiver. Trigger pulses can also bemixed with thevideo since there isnoconflict intime, but some method ofseparating them atthe receiving station must beprovided. 
 327. Sensors 2019 ,19, 1529 Author Contributions: Conceptualization, Y.W.; Methodology, Y.W. and M.Y.; Validation, Y.W. 
 Near Cologne, December 1944. makeshift, and there was later designed aplotting board, shown inFig. 7.17, which embodied many improvements. 
 SION WITH A DUTY CYCLE OF NEARLY   WHICH IS MUCH HIGHER THAN OLDER  DUTY CYCLE SYSTEMS !LTHOUGH IT MAY HAVE BEEN DESIRABLE TO GO TO A HIGHER DUTY CYCLE AND LOWER PEAK POWER TO MAKE THE SOLID 
 The method that will now bede- scribed issimilar tothat just V2 treated inthat positive and nega- tive signals are “balanced.” It+200V differs, however, inthat thewave- ‘L form includes aquiescent period, immediately preceding each clWaveform sweep, during which thewaveformv, T——. has its average value, sothat--- c~ —-- 0 %1c,there isnonecessity forprecise { control ofthetrigger (Fig. 13.45). 
 The seasonal trend of ducting conditions in the Bay of Bengal is the same as in the Arabian Sea, with standard conditionsduring the summer southwest monsoon. Ducting is found during the dryseason. Figure 1.10 - Ducting. 
 DEPENDENT     TRACKING ERRORS:ERO RANGE SETTING2ANGE DISCRIMINATOR SHIFT    SERVO UNBALANCE2ECEIVER DELAY2ECEIVER THERMAL NOISE-ULTIPATH3ERVO ELECTRICAL NOISE3ERVO MECHANICAL NOISE6ARIATION IN RECEIVER DELAY 2ADAR 
 With subsonic aircraft  targets and transmitter frequencies in the middle range of the microwave frequency region, the  doppler frequencies usually fall within the passband of the ear. If audio detection were desired  for those combinations of target velocity and transmitter frequency which do not result in  audible doppler frequencies, the doppler signal could be heterodyned to the audible range. The  doppler frequency can also be detected and measured by conventional frequency meters,  usually one that counts cycles. 
 STATE MODULES DURING AN ENTIRE PULSE  AND EACH POWER SUPPLY MUST RECHARGE ITS CAPACITOR BANK SMOOTHLY BETWEEN PULSES WITHOUT DRAWING AN EXCESSIVE  CURRENT SURGE FROM THE POWER LINE !S A RESULT OF UNAVOIDABLE LOSSES IN COMBINING THE OUTPUTS OF MANY SOLID 
 Example prf's and frequencies are shown. Several "representative" examples of  clutter are indicated, based on published data for o,, which for the most part dates back to  World War 11.46.49 Although each type ofclutter is shown at a particular value ofa,, nature is  more variable than this. Actual measurements cover a range of values. 
 The observable features of  the sea surface that best suggest an origin for the sharp localized radar returns called sea  spikes  are surface events that are themselves sharply localized, events including break - ing waves of all sizes, induced either by the wind or by nonlinear interactions among  wave systems. Large-scale breaking waves display two characteristic behaviors—   spilling , in which an unstable wave peak unravels, and plunging , where the peak curls  over on itself and crashes onto the front face as a cascade of water masses, ending in a  chaotic jumble.20 Another different event is the microbreaker , a small, transient shock  front induced by a puff of wind or another wave. As noted earlier, highly averaged wave  spectra cannot disclose the morphology of such surface features, and, unfortunately,  physical oceanography is still unable to provide a generally satisfactory description or  characterization of wave breaking.21 Nevertheless, there are two useful heuristic param - eters relating elements of a breaking wave scene to wind speed. 
 be applied to a continuous, single-target tracking radar when the error signal is processed  digitally rather than analog. Indeed, the equations describing the a-/I tracker are equivalent to  the type II servo system widely used to model the continuous tracker.)  If, for some reason, the track-while-scan radar does not receive target information on a  particular scan, the smoothing and prediction operation can be continued by properly  accounting for the missed data." However, when data to update a track is missing for a  sufficient number of consecutive scans, the track is terminated. Although the criterion for  terminating a track depends on the application, one example suggests that when three target  reports are used to establish a track, five consecutive misses is a suitable criterion for  terminati~n.~~  One of the corollary advantages of ADT is that it effccts a bandw~tltll retliiction 111 ttlc  output of a radar so as to allow the radar data to be tra11sm1ttt.d to another location via  narrowband phone lines rather than wideband microwave links. 
 Ice is a fair reﬂector, depending on aspect. Land areas varyin their reﬂection qualities depending on the amount and type of vegetationand the rock and mineral content. Wood and ﬁber glass boats are poorreﬂectors. 
 SARILY VALID WHEN ADVANCED ADAPTIVE SPATIAL AND TEMPORAL PROCESSING TECHNIQUES ARE EMPLOYED BECAUSE INTERFERENCE REJECTION EFFICACY IS ENHANCED BY HIGHER INTERFERENCE 
 The accurate determination of the direction of targets is  made with the monopulse difference pattern. The accuracy of the null position of the  difference pattern is, therefore, of interest. With quantized phase shifters, the position  of this null can be moved with a granularity that is a function of the bit size. 
 M. Ellis, and J. VanAndel, “The radar echo classifier: a fuzzy logic algorithm for  the WSR-88D,” presented at 83rd AMS Annual Meeting (3 rd AI Conf.) , P1.6, Long Beach, 2003. 
 TO 
 Dennis and Gibbs23 made an assessment of the  sensitivity of time sidelobe level to linearity and showed the ratio of sidelobe to peak  level was dependent on the sweep linearity. Practically, the effect of a nonlinearity of  a few percent is to cause significant time sidelobes, as this needs to be compensated in  the transmitter modulator design. The SFCW radar transmits a series of incremental frequencies and stores the  received IF signal to then carry out a Fourier transform reconstruction of the time- domain equivalent waveform. 
 Results of preliminary tradeoffs on multiple-target tracking radars indicate36 that either a Ka-band or an X-band phased array radar would be the preferred approach. Remote-Sensing Missions.64 SBR will participate in many remote-sensing missions for observation of the earth and the planets. The SIR series is expected to have the capability to image the earth's surface by using all polarization states (HH, VV, and HV) and with multiple frequency bands. 
 BAND RADARS SIMILAR TO  THE %,$/2! RADAR FOR HURRICANE TRACKING AND RESEARCH *0, DEVELOPED THE !2-!2  RADAR TO TEST SPACE RADAR CONCEPTS FOR THE 4ROPICAL 2AINFALL -EASUREMENTS -ISSION  42--  4HE 5NIVERSITY OF 7YOMING USES A  
 Pulse-timing Methods.—The simplest method ofusing pulse-timing techniques torelay sine and cosine information can beunderstood by referring tothetiming diagram ofFig. 17.12. Abasic pulse occurs once each radar cycle. 
 Inaddition tothedevelopments carriedoutintheUnitedStatesandGreatBritain,radar wasdeveloped essentially independently inGermany, France,Russia,Italy,andJapanduring themiddleandlatethirties.12Theextentofthesedevelopments andtheirsubsequent military deployment varied,however. Allofthesecountries carriedoutexperiments withCWwave interference, andeventhoughtheFrenchandtheJapanese deployed suchradarsopera­ tionally, theyprovedoflimitedvalue.Eachcountry eventually progressed topulseradar operation andtheadvantages pertaining thereto. Although theadvantages ofthehigher frequencies werewellrecognized, exceptfortheUnitedStatesandGreatBritainnoneofthe othersdeployed radaratfrequencies higherthanabout600MHzduringthewar. 
 W. Bogle: Directional Sea Spectrum Determina­ tion Using HF Doppler Radar Techniques. IEEE Trans .. 
 BEAM 
 L. Weber, A. S. 
 (The value of -f,.n/t,.h  was taken as 1.57 x 10-7 m-1.) Since atmospheric ducts are not usually deep, extended range  propagation is more likely to be experienced at the higher microwave frequencies than at the  lower frequencies. Unlike standard waveguide propagation, the cutoff wavelength for ducting  ;/)  (/ ) ·~  ~ .:_ . 452 INTRODUCTION TO RADAR SYSTEMS  does not sharply divide the regions of propagation and no propagation, so that radiation  whose wavelength is several times the" cutoff wavelength" may be affected by the duct. 
 It is noted that the RWR detection performance is inversely proportional to R2 rather than to R4 of the radar target detection equation. For this reason, the RWR can detect a radiating radar at distances far beyond those of radar's own target detection capability. The radar-versus-interccptor problem is a battle in which the radar's advantage lies in the use of matched filtering, which cannot be duplicated by the interceptor (it does not know the exact radar waveform), while the interceptor's advantage lies in the fundamental R2 advantage of one-way versus two-way radar propagation.10 9.4 ELECTRONICCOUNTERMEASURES The objectives of an ECM system are to deny information (detection, position, track initiation, track update, and classification of one or more targets) that the radar seeks or to surround desired radar echoes with so many false targets that the true information cannot be extracted. 
 # 
 and W. E. Kock: Microwave Antenna Measurements, Proc. 
 Charging  impedance  frnn·-o- LcH  Energy Trigger  in sourse --~  Hydrogf!n  lhyralron Charging  d,ode  Bypass  diode pulse -forming network ~"ITrl  Le  De spiking  cicuit Pulse  transformer  (]?"""  Damping  network  Figure 6.14 Diagram of a line-type modulator. RADAR TRANSMITTERS 215  as a thyratron or ignitron is capable of handling high power and presents a low impedance  when conducting. However, a gas tube cannot be turned off once it has been turned on unless  the plate current is reduced to a small value. 
 EARTH IF  2G IS  RELATIVELY LARGE SEE 3ECTION  OF 3ULLIVAN (OWEVER  THE SHADOW METHOD WORKS ONLY  FOR AN ISOLATED  RELATIVELY HIGH OBJECT ON ESSENTIALLY FLAT TERRAIN EG  &IGURE   ,AYOVER 3!2 PROCESSING SORTS TARGET RETURNS INTO BINS PIXELS  DEPENDING ON THE  RANGE 2 AND VELOCITY  V OF THE TARGET RELATIVE TO THE PLATFORM )F TWO OR MORE TARGETS HAVE  THE SAME 2 AND V  THEN THEY WILL BE PLACED AT THE SAME LOCATION IN THE 3!2 IMAGE 7E SHALL DEFINE A  LAYOVER CONTOUR AS THE LOCUS OF POINTS IN $ SPACE SUCH THAT AN  OBJECT AT ANY OF THE POINTS WILL BE ASSIGNED TO THE SAME LOCATION IN A 3!2 IMAGE  !S SHOWN IN &IGURE   A LAYOVER CONTOUR IS THE INTERSECTION OF A CONSTANT 
 6, pp. 356-365, Nov., 1967. Also, Report of NRL Progress, pp. 
 14, no 1, January/February 1987.  4. B. 
 VERTER INPUT NOISE LEVEL RELATIVE TO THE !$ CONVERTER NOISE IS CRITICAL TO ACHIEVING THE OPTIMUM TRADE 
 Crowder, H. A.: Ground Clutter Isodops for Coherent Bistatic Radar, IRE Nat. Conv. 
 4AYLOR INSTABILITIES  ATMOSPHERIC  GRAVITY WAVES  AND EQUATORIAL SPREAD & v * 'EOPHYS 2ES  VOL   PP  n     $ , ,UCAS AND ' 7 (AYDON  h0REDICTING STATISTICAL PERFORMANCE INDEXES FOR HIGH FRE 
 NOISE RATIO FROM A MATCHED FILTER.   -4) 2!$!2  Ó°ÓÎ 4HE MAXIMUM SIGNAL 
 52.Sherman, S.M.:Complex Indicated AnglesApplied toUnresolved RadarTargetsandMultipath, IEEETrans.vol.AES-7,pp.160-170. January, 1971. 53.Albersheim, W.J.:Elevation Tracking Through ClutterFences.SlIpplemellC toIEEETnms.,vol. 
 TION IS TO BE GENERATED  (OWEVER  DETERMINING THE DOPPLER CENTROID OF THE AZIMUTH SPECTRUM WITH RESPECT TO ZERO DOPPLER EMERGES AS A DOMINANT ISSUE )F THE AZIMUTH ANTENNA BORESIGHT IS PERFECTLY ORTHOGONAL TO THE INERTIAL ORBIT PLANE  THE %ARTHS ROTA 
 697-698, May, 1957.  44. Van Vleck, J. 
 PHASE TO CAUSE A LARGE  REFLECTION IN A TYPICAL ELEMENT #ONSIDER AN ARRAY IN WHICH THE VELOCITY OF THE SURFACE WAVE IS THAT OF FREE SPACE  4HE DIFFERENCE IN THE PHASE OF THE VOLTAGES COUPLED FROM AN ADJ ACENT PAIR OF ELEMENTS  TO ELEMENT  E IN &IGURE   IS RELATED TO THE SCAN ANGLE BY    P LP LP LSS S    SIN  SIN  PP  4HE COUPLINGS WILL BE IN PHASE WHEN $X   O   OR WHEN  S L   SINP  4HIS IS SEEN TO BE EXACTLY THE SAME  CONDITIONS AS PREVIOUSLY DETERMINED FOR THE EMER 
 ¯ ¯   QQ QQPP    WHERE THE LOWER INTEGRAL IS TAKEN OUTSIDE THE MAIN 
 A. Farina and L. Timmoneri, “Real time STAP techniques,” Electronics & Communications  Engineering Journal, Special Issue on STAP , vol. 
 Cahoon: Methods of Predicting the Atmospheric Bending of  Radio Rays. Natl. Bur. 
  ARRAY SHOULD SUFFICE )F ACCURATE PREDICTION OF THE ARRAY PERFORMANCE IS REQUIRED  MANY MORE ELEMENTS ARE NEEDED THAN ARE INDICATED ABOVE   )T IS OFTEN CONVENIENT TO ASSUME THAT THE ARRAY IS INFINITE IN EXTENT AND HAS A UNIFORM  AMPLITUDE DISTRIBUTION AND A LINEAR 
 B. Wiesner: Application of Correlation Analysis to the  Detection of Periodic Signals in Noise, Proc. IRE, vol. 
 ` 
 CAL COVERAGE AT MODERATE COST BY MEANS OF THE WIDELY USED LOG 
 P. Ia. Ufimtsev, “Method of edge waves in the physical theory of diffraction,” U. 
 A time delay is necessary in the  specification of the filter for reasons of physical realizability since there can be no output from  the filter until the signal is applied. The frequency spectrum of the received signal may be  written as an amplitude spectrum IS( f) ( and a phase spectrum exp [- j4,( f )]. The matched-  filter frequency-response function may similarly be written in terms of its amplitude and phase  spectra / H( f) ) and exp [-I&,( f )]. 
 301. ch05.indd   44 12/17/07   1:27:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Janu·  ary, 1970.  97. Millimeter Waveguide Systems, Microwave J., vol. 
 The Warloc radar was about  three orders of magnitude more capable than most previous radars used for millime - ter-wave radar. This experimental Warloc radar was employed to demonstrate at W  band the ISAR imaging of moving targets, cloud structure, low-angle operation, and  unusual atmospheric research including what have been called “air spikes.” ch10.indd   18 12/17/07   2:19:35 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 29. J. R. 
 4ARGET 4RACK MODE (OWEVER  THE USE OF !'# DEGRADES THE SYSTEMS SENSITIVITY  SO LARGE &)'52%  0OSTDETECTION 34# LEVELS          
  SATELLITE v  0ROCEEDINGS  OF THE )%%%  VOL   PP n    2 "AMLER  - %INEDER  " +AMPES  ( 2UNGE  AND . !DAM  h324- AND BEYOND #URRENT SITU 
 For example, if 10 percent of the radiated power is in the sidelobes, the average sidelobe level is —10 dB, where dB refers to the number of decibels by which the average sidelobe level is below the gain of an isotropic (ideal) radiator. In theory, extremely low sidelobes can be achieved with aperture illumination functions that are appropriately tapered. This leads to the well-known tradeoffs among gain, beamwidth, and sidelobe level.19 In order to keep the beamwidth small with low sidelobes, a larger and more costly antenna is needed. 
 #   
 For this reason early magnetrons were not tunable, and only alater need forincreased flexibility ofradar systems forced thedesign oftunable tubes. The practical advantage oftunable over fixed-tuned magnetrons isobvious. Ifoperation onanumber offrequencies iscontemplated, a single tunable magnetron can replace awhole set offixed-frequency magnetrons, and only with atunable magnetron isitpossible ingeneral toobtain r-fpower ataspecified frequency. 
 4.8). The output of the IF amplifier is fed to I and  Q phase detectors. The analog signals from the phase detectors are converted into 10-bit  digital words by A/D converters. 
 J. B. Tsui, Digital Techniques for Wideband Receivers,  2nd Ed., Raleigh, NC: SciTech Publishing  Company, 2004, pp. 
 These materials are too flimsy or too  heavy for most military applications. The pyramidal absorber used to suppress wall reflections in indoor chambers  represents a particularly effective method of varying the effective impedance “seen”  FIGURE 14.27  Performance of Jaumann absorbers  with as many as four sheets. All four of these traces were  optimized for maximum bandwidth at the –20 dB level. 
 41.Crain,CM.:SurveyofAirborne Microwave Refractometer Measurements, Proc.IRE,vol.43, pp.1405-1411, October, 1955. 42.Schaper,L.W.,Jr.,D.H.StaeHn,andJ.W.Waters:TheEstimation ofTropospherlc Electrical Path LengthbyMicrowave Radiometry, Proc.IEEE,vol.58,pp.272-273, February, 1970. 43.Skolnik, M.I.:RadarHorizon andPropagation Loss,Proc.IRE,vol.45,pp.697-698, May,1957. 
 For this reason, many solid-state transmitters consist  of amplifier modules that feed either rows, columns, or single elements of an array  antenna. Especially in the last-named case, it is necessary to build the modules (and  usually their power supplies) into the array structure. Generally, solid-state devices  or modules are combined in one of three fundamental configurations to generate the  required transmitter power levels. 
 SIBLE ANGULAR WIDTH OBTAINED BY A LONGER PULSE OR A WIDER FILTER FOR A #7 
 QUALITY METRICS )1-S  DESCRIBED IN THE FOL 
 An alternative approach for interfering targets is to use log video. By taking the  log, large samples in the reference cells will have less effect than linear video on the  threshold. The loss associated with using log video, rather than linear video, is 0.5 dB   FIGURE 7.18  Detection probability versus SNR for a Swerling Case 2 primary target  (after J. 
 Principles  of Modern Radar: Basic Principles -Mark A. Richards, James A. Scheer, William A. 
 MENT IS FED BY AN AMPLIFIER MODULE AND THE WAVEFRONT IS FORMED  IN SPACE 4HE COM 
 POLARIZED MODES  AND EXPERIMENTAL MODES  INCLUDING 3POT3!2 %ARLY MISSION CALIBRATION AND VALIDATION STUDIES VERIFIED THAT THE RADAR IS PERFORMING AS INTENDED -ORE ON 0!,3!2 APPEARS LATER IN THIS SECTION4!",%  2SAT 
 The angular location of the target is found with a directive antenna (one with a narrow beamwidth) to sense the angle of arrival of the echo signal. If the target is moving, a radar can derive its track, or trajectory, and pre- dict the future location. The shift in frequency of the received echo signal due to the doppler effect caused by a moving target allows a radar to separate desired moving targets (such as aircraft) from undesired stationary targets (such as land and sea clutter) even though the stationary echo signal may be many orders of magnitude greater than the moving target. 
 4.14b to d were derived from the low-pass filter characteri!.tic of  Fig. 4.14a. This type of filter characteristic may be obtained with a single delay line in cascade  with a double delay line as shown in Fig. 
  AIRPORT SURVEILLANCE  RADAR AND IN THE 732 
 GATE 
 10. B. D. 
 Leonov and K. J. Fomichev, Monopulse Radar , Norwood, MA: Artech House, Inc., 1987. 
 TIVE DETECTOR IS MORE COMPLICATED 5SUALLY TWO PARAMETERS ARE ESTIMATED  THE MEAN AND THE VARIANCE  AND A THRESHOLD OF THE FORM 4+  }} MSIS USED 4HE SAMPLED MEAN  IS EASILY OBTAINED (OWEVER  THE USUAL ESTIMATE OF THE STANDARD DEVIATION  }}  SM £ 
 587-589,  April, 1967.  42. Pollon, G. 
 16. K. S. 
 Master’s Thesis, August 2016. Available online: https://essay.utwente.nl/71435/1/GROOTJANS_MA_EWI.pdf (accessed on 30 November 2017). 6. 
 However, this is  usually not important since small changes in the probability of false alarm result in even  smaller changes in the threshold level because of the exponential relationship of Eq. (2.26).  Thus far, a receiver with only a noise input has been discussed. 
 The  frequency dependence indicated by the data of Ref. 37 is independent of the polarization and  of the angle of incidence (at least over the range from 8 to 30°).  Measurements of crops40 and dry trees41 indicate that above X hand, a0 varies approxi­ mately linear with frequency, even up to 3.2-mm wavelength. 
 When no other input  data is available, the IREPS utilizes a stored library of historic refractivity and clinlatology  statistics as a function of the latitude, longitude, season, and time of day. When historic data  is used the output is a prediction of propagation performance in probabilistic terms. Also  stored are the necessary system parameters for the various electromagnetic systems whose  predicted propagation performance is desired. 
 D" BEAMWIDTH !N ANTENNA BEAM SHAPE OF SIN  5 5  TERMI 
 Skolnik (ed.),  McGraw-Hill Book Co., Inc., New York, 1970.  71. Oakley, B. 
 Although this helps to set the threshold to appropriate levels, it does not remove  the intrusive “spiky” component of sea clutter that can make wanted targets difficult to  observe. However, over a typical antenna scan time of a marine radar (2–3 seconds), the  spikes are normally decorrelated, whereas returns from targets are generally correlated— therefore, the application of scan-to-scan correlation can improve the target-to-clutter  ratio, but it will also remove weak and fast-moving targets. Many years ago, Croney6  showed that significant improvements in detecting small targets in sea clutter could be  obtained by ensuring that integration was performed at intervals longer than the decor - relation time period of the sea clutter. 
             
 EQUIVALENT  R    RANGES FROM  ^  
 -Table 16.1summarizes the stability requirements. Itshould bementioned that these figures represent almost ideal conditions, inwhich theclutter tobecanceled shows nofluctuations ofitsown. Ifforany reason (such asrapid scanning rate) theclutter should fluctuate by10or15percent from pulse topulse, there would be nosense incanceling to3or4percent. 
 Record, vol. 6, pt. 5, pp. 
 In fact, biological oils, produced by bacteria, algae, and plankton, can be found everywhere on the world's oceans and form natural slicks in those regions that combine the greatest oil concentration with the lowest wind speeds, e.g., close to continental shorelines.61 Human-made contaminants can, of course, have the same effect. A layer of oil only 1 molecule thick will significantly affect the ability of the surface to support wave motions, but this layer must be continuous. The ad- jacent molecules then sense each other and form a film that is resistant to hor- izontal compression. 
 BEAM EFFECTS WOULD BE INCLUDED IN THE PLATFORM 
 Ducting Areas Although ducting conditions can happen any place in the world, the climate and weather in some areas make their occurrence more likely. Insome parts of the world, particularly those having a monsoonal climate,variationinthedegreeofductingismainlyseasonal,andgreatchangesfrom daytodaymaynottakeplace.Inotherpartsoftheworld,especiallythoseinwhich low barometric pressure areas recur often, the extent of nonstandardpropagation conditions varies considerably from day to day. Figure 1.11 illustrates the different places in the world where known ductingoccursfrequently.Refertothemaptoseetheirlocationinrelationtothe climate that exists in each area during different seasons of the year. 
 A better criterion for selecting the aperture illumination might  be one which maximizes the radiated energy within-a specified angular region.5 Such illumina­ tions are more typical of radar antenna practice than the uniformly illuminated aperture.  In a monopulse tracking antenna, uniform illumination might be desirable to maximize  directivity when the target is being tracked by the center of the beam. However, a monopulse  antenna with a uniform illumination for the sum-pattern will have a poor difference-pattern,  even if the high sidelobes can be tolerated. 
   ASYMPTOTICALLY !GAINST A SLOWLY MOVING SOURCE OF CLUTTER EG  BIRDS   THE PROBABILITY OF DETECTION  MAY INCREASE AS THE CLUTTER SOURCE CROSSES THE BOUNDARY BETWEEN TWO CLUTTER MAP CELLS 4O PREVENT THIS  A SPREADING TECHNIQUE CAN BE USED  THROUGH WHICH EACH CLUTTER MAP CELL WILL BE UPDATEDNOT ONLY WITH RADAR RETURNS FALLING WITHIN ITS BOUNDARIES  BUT ALSO . 
 The output of a  normal PPI display is stored in either an analog or digital storage medium, and the stored  information is read out and displayed on a conventional TV monit~r.~~.~~.~~ The conversion  of the radial rho-theta raster of the PPI to the rectangular raster of the TV represents a  "scan conversion," hence the name. )The stored display may be read out repetitively to  produce a bright flicker-free display. The display is bright not only because the stored  information is displayed at a sufficiently high repetition rate to appear conlin~ious, bill  also because TV monitors with typical brightness of 50 to 100 foot-lamberts are inherently  brighter than the conventional CRT display. 
 While clutter maps  can be used with frequency-agile radars and on moving platforms (e.g., radars on  ships), they are not nearly as effective in these environments. Target Resolution.  In automatic detection systems, a single large target will prob - ably be detected (i.e., cross a detection threshold) many times, e.g., in adjacent range  cells, azimuth beams, and elevation beams. 
 Trunk and J. D. Wilson, “Automatic detector for suppression of sidelobe interference,” in  IEEE Conf. 
 Ship Classiﬁcation in High-Resolution SAR Images via Transfer Learning with Small Training Dataset. Sensors 2019 ,19, 63. [ CrossRef ][PubMed ] 19. 
 86. Mendez. A. 
 If low sidelobes are specified away from the principal planes, it may be necessary to maintain square corners, as shown in Fig. 6.1e. Parabolic reflectors still serve as a basis for many radar antennas in use today, since they provide the maximum available gain and minimum beamwidths with the simplest and smallest feeds. 
 Curves3,4,and5aresimilartocurve2,except thattheyapplytoafree-space signalof110,55,and27.5nautical miles,respectively. Curve6 500.------,.----.----------,,------,---,,,--.,.------, 400 4i300-0 :2:;:. o +­ l1> ~200- oI-Figure 12.8Contours of..radar coverage" forradarheightof200ft abovecurvedearth.(I)Geometrical line-or-sight contour fork=!;(2) constant-radar-signal contour inthe diffraction region,assuming aradar capableofafree-space rangeof220 nmi,vertical polarization, seawater, k=1.1=500MHz;(3)sameas(2), butfor110nmifree-space range; (4)sameas(2),butfor55nmifree­ spacerange;(5)sameas(2),butfor oL.. 
 J., and D. L. Moffett: An Experimental Study of Bistatic Scattering from Some Small, Absorber-Coated, Metal Shapes, Proc. 
 36 40. Oct. 25 2%. 
 AP-8. pp. 629-631. 
 At10cmcoaxial cables carry thelocal-oscillator power tosepa- rate radar and AFC mixers, but at3cmdouble mixers areused inwhich thetwo crystals areonopposite sides ofthelocal oscillator. Figure 11.29 shows awaveguide mixer and other r-fcomponents forthe 3-cm band with AFC and beacon features. 11.9. 
 17because television does not require the use ofpersistent phosphors, with their low maximum level oflight intensity, intheaircraft cockpit, where thelevel ofambient light islikely tobehigh. Onthebasis oftheassumption that display ofallaircraft inthe pic- ture offered apilot would beuseless and confusing, itisproposed to separate the radar signals according tothe altitude atwhich the corre- sponding aircraft areflying. Thus, forexample, apilot at5000 ftwould besent signals sho~}-ing the positions ofallaircraft inhisneighborhood and inthealtitude range from 3500 to6000 ft. 
 EXTKACTION OF INFORMATION AND WAVEFORM DESIGN 401  might also be measured, but its precise value is usually not important except insofar as it  influences the signal-to-noise ratio.  In this section the theoretical accuracies of radar measurements will be derived. To  simplify the analysis. 
 *AMMING SIGNALS THAT SURVIVE THE ANTENNA %##- EXPEDIENTS CAN  IF LARGE ENOUGH  SATURATE THE RADAR PROCESSING CHAIN 7IDE DYNAMIC RANGE RECEIVE RS NEED TO BE USED TO  AVOID SATURATION ! LOGARITHMIC LOG  RECEIVER MIGHT HELP AGAINST NOISE JAMMING   BUT IT HAS DETRIMEN 
 15.12. This derivation assumes a linear system. That is, it is assumed that the voltage envelope of the echo sig- nals, as the antenna scans past a point target, is identical to the two-way antenna voltage pattern. 
 Note that the spatial variance used below refers to the azimuth spatial variance if without additional denotations. Sensors 2019 ,19, 213; doi:10.3390/s19010213 www.mdpi.com/journal/sensors 51. Sensors 2019 ,19, 213 ,GHDOWUDMHFWRU\5HDOWUDMHFWRU\ 7LPH )UHTXHQF\Ba(A) Ba(B) Ba(C) fdc(A) fdc(B) fdc(C) Figure 1. 
 TIVITY FACTOR AND ATTENUATION  CAN BE USED TO OBTAIN BOTH PARAMETERS OF THE DROP 
 4.23).  When k = 1, the peak response occurs at f= l/NT as well as .f'= 1/T + 1/NT, 2/T +  IINT, etc. For k = 2, the peak response is at f = 2/NT, and so forth. 
 Dong, S.; Samsonov, S.; Yin, H.; Ye, S.; Cao, Y. Time-series analysis of subsidence associated with rapid urbanization in Shanghai, China measured with SBAS InSAR method. Environ. 
 DUCE RADAR SYSTEMS OPERATING OVER A RESTRICTED BAND  MUCH LESS THAN THE OVERALL RADAR  BAND  WHICH REMOVES ANY NEED FOR INDIVIDUAL SQUINT COMPENSATION WHEN MAGNETRONS  ARE REPLACED 4HE REQUIRED SIDELOBE PERFORMANCE IS NOT DEMANDING 4ABLE    AND SO SIMPLE APERTURE DISTRIBUTIONS  SUCH AS PEDESTAL 
 D" FREQUENCY RESOLUTION WIDTH  FOR SPECTRAL ANALYSIS USING A RECTANGULAR WINDOW OF TIME DURATION EQUAL TO THE TRANSMIT PULSEWIDTH IS    $F4     4HE   
 TIii' l'I.ITIRONICALI.Y STl'l'RED PHASELJ ARRAY ANTENNA IN RADAR 311  , -Bo  ------··---------~  Beam Beam Beam  Na.3 No.2 No.1  Figure 8.25 Simultaneous postarnplifier beam formation. rp0 = constant phase; I rjJ 1 -<Po I = I ~rp I  I 2rr(d/1.) sin 00 I- coll\'enient method for obtaining multiple beams at IF. Beam-forming at IF is possible since  phase is preserved during frequency translation from RF to IF (except for the constant phase  shirt introduced by the common local oscillator). 
 310 essential point ofdifference:l therate offluctuation ofthereceiver output isdetermined bythe bandwidth ofthe receiver, whereas the rate of fluctuation, intime, ofthe echo from agiven element ofvolume inthe rain isfixed bythetime required forthe drops inthevolume toassume anew configuration. Thk isordinarily solong that several successive radar pulses find thedrops disposed innearly thesame way, that is,with changes inrelative positions amounting toasmall fraction ofawave- length only. Aquantitative formulation ofthis statement isderived in Vol. 
 GUITY FUNCTION APPROACHES THE IDEAL THUMBTACK  PROVIDING BOTH DOPPLER AND RANGE  INFORMATION &IGURE    !LL SIDELOBES  EXCEPT FOR A FEW NEAR THE ORIGIN  HAVE  AN AMPLITUDE OF  - ! FEW SIDELOBES CLOSE TO THE ORIGIN ARE ABOUT TWICE AS LARGE   OR ABOUT  -  WHICH IS CHARACTERISTIC OF #OSTAS CODES 4HE COMPRESSION RATIO OF A  #OSTAS CODE IS ABOUT -  4HE #OSTAS CODE IS A BURST OF  - CONTIGUOUS UNCODED PULSE WAVEFORMS  EACH WITH A  DIFFERENT FREQUENCY SELECTED FROM A FINITE SET OF  - EQUALLY SPACED FREQUENCIES THAT ARE &)'52%     4IME 
 This can be  accomplished by changing the radar frequency from pulse to pulse in an unpredictable fashion  over the entire tuning band available to the radar. A radar capable of changing its frequency  from pulse to pulse is said to possessji·equency agilit}'. (Even in the absence of ECM, frequency  agility has advantages in filling in the nulls of the elevation radiation pattern and in decorrelat­ ing target echoes so as to increase the probability of detection.) A jammer can also b1.: forced to  widen its jamming band if there are many radars operating within the same geographic area,  each at a different frequency distributed over the available radar tuning range. 
 The behavior shown here is representative of that found generally: sea clutter is strongest viewed up- wind, weakest viewed crosswind, and of intermediate strength viewed down- wind, the total variation being about 5 dB. At High Grazing Angles. The top curve in Fig. 
 TheB sandwich isthemicrowave analogofmatc;hing coatings usedinopticallenses.Although itis superiorelectrically totheAsandwich, itisheavierandisnotgenerally suitedtotheenviron­ mentalconditions encountered inaircraft.Itisnotcommonly used. TheCsandwic11 canbethought ofastwoback-to-back Asandwiches. Itconsistsoffive layers.Therearetwoouterskins,acenterskin,andtwointermediate cores.Itisusedwhenthe ordinary Asandwich doesnotprovidesufficient strength. 
 For larger number of pulses in the CPI a more systematic approach to filter design is desirable. If a doppler filter design criterion is chosen that requires the filter sidelobes outside the main response to be below a specified level (i.e., providing a constant level of clutter suppression), while simultaneously minimizing the width of the filter response, a filter design based on the Dolph-Chebyshev distribution provides the optimum solution. Properties and design procedures based on the Dolph-Chebyshev distribution can be found inREALTlVE DOPPLER SHIFT fT FIG. 
                             . 
 M. Maher: Effect of Surface Reflections on Rain Cancellation of Circularly  Polarized Radars, IRE Trans., vol. AP-7, pp. 
 The indicating lamps showed when the attenuator was in use and when zeroattenuation was selected. As mentioned above, there were signi ﬁcant problems with the development of attenuator type 58. Moreover, by 1945 the Germans had introduced the schnorkel,which could only be detected by radar at very short range. 
 POLARIZATION  IN WHICH THE  POLARIZATION STATES ARE SWITCHED BETWEEN TRANSMISSIONS OR RECEPTIONS  BUT THE PULSE 
 23.Green,P.I.,Jr.:TheOutputSignal-to-noise RatioofCorrelation Detectors, IRETrans.,vol.IT-3, pp.10-18,March,1957. 24.Peterson, W.W.,T.G.Birdsall, andW.C.Fox:TheTheoryofSignalDetectability, IRETrans., no.PGIT-4, pp.171-212, September, 1954. 25.Middleton,D.:Statistical Criteria fortheDetection ofPulsedCarriers inNoise,pts.I~ndIf,J.App/. 
 FIG. 5.3 A UHF 115-W power transistor for long pulse and high duty cycle, used in the PAVE PAWS transmitter. (Photograph courtesy of MIA-COM, PHI.}System OTH NAVSPASUR AN/SPS-40 PAVE PAWS BMEWS AN/TPS-59 RAMP MARTELLO S723 MATCALS AN/SPS-48 AN/TPQ-37 HADRFrequency, MHz 5-30 217 400-450 ( 420-450 420-450 1215-1400 : 1250-1350 1235-1365 2700-2900 2900-3100 < 3100-3500 3100-3500 !Pulse/duty CW CW SO JJLS at 2% 16 ms at 20% 16 ms at 20% I ms at 20% 100 IJLS at 10% 150 JJLS at 4% 100 IJLS at 10% 40 JJLS at 4% 100 M-S at 25% 800 IJLS at 23%Transistor performance Peak power, W 130 100 450 115 115 55 105 275 63 55 30 50Gain, dB 14.0 9.2 8.0 8.5 8.5 6.6 7.5 6.3 6.5 5.9 5.0 5.3Efficiency, percent 60 72 60 65 65 52 55 40 40 32 30 35 . 
 TION WITHOUT NECESSARILY HIGHLIGHTING A VESSELS MILITARY PURPOSE 4HE BIGGEST INFLUENCE ON THE REQUIREMENTS OF SHIPBORNE #-2 COMES FROM THE  )NTERNATIONAL -ARITIME /RGANIZATION  )-/  ! 5NITED .ATIONS AGENCY BASED IN  ,ONDON  )-/ IS CONCERNED WITH INTERNATIONAL MARITIME SAFETY AND THE PROTECTION OF THE MARINE ENVIRONMENT )N PARTICULAR  )-/ ISSUES REQUIREMENTS AND GUIDELINES ON THE INSTALLATION AND USE OF RADAR EQUIPMENT ON COMMERCIAL SHIPS 4HESE ARE VIGOROUSLY ENFORCED BY THE LAWS OF INDIVIDUAL MARITIME STATES 4HE PURPOSE OF SHIPBORNE RADAR  AS DEFINED BY )-/  IS TO hASSIST IN SAFE NAVIGATION AND IN AVOIDING COLLISION BY PROVIDING AN INDICATION  IN RELATION TO OWN SHIP  OF THE POSITION OF OTHER SURFACE CRAFT  OBSTRUC 
 For the higher wind speeds and fully  developed seas encountered in the North Atlantic, the percentage of sea spikes in this  population was found to grow as the 3.5th power of the wind speed, which, interest - ingly, is the same wind-speed dependence shown by the percentage of whitecaps seen  on the surface,22 which, as noted in Section 15.2, are tracers for breaking waves. ch15.indd   16 12/15/07   6:17:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 57, pp. 324-335, March, 1969.  24. 
 WIDTH DIVERSITY  HIGH RESOLUTION IS OBTAINED USUALLY AT SHORT RANGE  WHEREAS FOR LONG 
 S. J. Goldman, Phase Noise Analysis in Radar Systems Using Personal Computers,  Chapter 2,  New York: John Wiley & Sons, Inc, 1989. 
 END ,.&%  SUBSYSTEM IS CONNECTED TO THE CIRCULATOR VIA A 0). DIODE LIMITER  WHICH PROTECTS THE ,.&% DURING PULSE TRANSMISSION 4HE MODULATOR TO THE MAGNETRON IS TYPICALLY A  PULSE FORMING NETWORK 0&.   BASI 
 The factors involve the target to  be detected (target returns of an unknown statistical nature), the natural environ - ment in which the target is embedded (e.g., clutter returns, unintentional interference,  uncontrollable environmental refraction, and absorption), the random nature of the  interference, and the radar itself (system noise temperature, signal distortions, etc.).  Nevertheless, radar range prediction made under average conditions provides a pre - liminary and useful indication of performance under ECM threat and ECCM design  effectiveness that produces baseline values prior to simulation and operational tests.  A classical book presents accurate detection range equations in a variety of practical  situations.189 In the second part of this section, a review of software tools available for  the prediction of range equation in jamming and chaff conditions is given. 
 Geotis, R. E. Passarelli, Jr., A. 
 SP–45, no. 12, pp.3104–3107, December 1997. 67. 
 3, pp. 1049–1052, July 2005. 72. 
 @2 S2  
 Conﬂicts of Interest: The authors declare no conﬂicts of interest. References 1. Yu, D.; Liu, W.L.; Zhang, Z.H. 
  TO  
 Clutter fence. Reflections from nearby mountains and other large clutter can sometimes be of  such a tnagnitude that it is not practical to completely suppress their undesirable effects by  eitlier MI'I or range gating. One tecl~tlique for reducing the magnitude of such large clutter-  RADAR CLUTTER 497 wellasthefactthatradarwavescanpenetrate thesurfaceandcanbescattered fromdiscon­ tinuities underneath thesurface. 
 Figure 25.13 shows the same 75 MHz IF tone, but sampled at 100 MHz and 60 MHz,  which are odd integer submultiples (1/3 and 1/5) of the original sample rate of 4× the IF  center frequency, 300 MHz. Note that odd samples still cycle between I and −I, and the  even samples switch between Q and −Q. Odd integer submultiples of 4× the IF center  frequency can, therefore, be viable alternative sample rates. 
 Radartutorial (www.radartutorial.eu)   7    Figure 8: True Bearing     Figure 7: Different height causes a different slant range  Radar Waveforms Minimum Range   The minimum detectable range (or bl ind distance) is also a consideration. When the leading edge of  the echo pulse falls inside the transmitting pulse, it is impossible to determine the “round trip time ”,  which means that the distance cannot be measured. The minimum detectable range Rmin depends  on the transmitters pulse with τ, and the recovery time trecovery of the duplexer. 
 4.27. The input on the left is from  the output of the I and Q AID converters. The three-pulse canceler and the eight-pulse doppler  filter-bank eliminate zero-velocity clutter and generate eight overlapping filters covering the  doppler interval, as described in the previous section. 
           "$   " $ "   "  !   "$   !"   "$  #  ". Ç°În  2!$!2 (!.$"//+  !SSOCIATION OF !CCEPTED $ETECTION WITH %XISTING 4RACKS  4HE GOAL OF DETECTION 
 Inorder todothis, itmust receive atiming pulse from themodulator, to indicate theinstant atwhich each oftheuniform range sweeps outfrom thecenter ofthe PPI tube should begin. Itmust also receive from the scanner information onthe direction inwhich the antenna ispointing, inorder that therange sweep beexecuted intheproper direction from the center ofthetube. Connections foraccomplishing this areindicated in theFig. 
 63-68, Jan., 1979. 3  368INTRODUCTION TORADAR SYSTEMS 55.Reynolds,1. F.,andM.R.Rosenzweig: LearntheLanguage ofMixerSpecification, MicrowQI'es, vol. 
 The resultant cross  section from such a target is assumed to behave according to the Rayleigh probability distribu­ tion. The prohahility or the apparent radar center lying outside the angular region of L/R  radians (in dne tracking plane) is 0.134, where R is the distance to the target. 32 Thus 13.4 per­ cent of the time the radar will not be directed to a point on the target. 
   3%! #,544%2  £x°Î£ !LTHOUGH SUCH COMPOSITE 
 THE 
 Óx°È  2!$!2 (!.$"//+  PASSBANDS EXTENDING RIGHT UP TO THEIR STOPBAND EDGES  SO THE WIDTHS OF INTERVENING  TRANSITION BANDS MUST BE COUNTED AS PART OF TWO 
 Generally, the interference power entering   the A/D converter is proportional to the bandwidth of components in front of the  ch06.indd   40 12/17/07   2:03:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 TIONS  BASED ON DATA COLLECTED BY 0IDGEON FOR # 
 SPLITTING  TECHNIQUES CAN BE USED TO REDUCE THE MEASUREMENT ERROR %VEN WITH BEAM 
 Thesystemengineer, however, ismoreconcerned withtheoveralltransmitter efficiency, whichistheratiooftheRFpoweravailable fromthe transmitter tothetotalpowerneededtooperatethetransmitter. If,forexample, theRF efficiency ofamicrowave tubewere40to50percent,thetransmitter efficiency mightbe20to 25percent.(Theactualnumber,ofcourse,variesconsiderably withtubetypeandapplication.) Therearetwobasicradar-transmitter configurations. Oneistheself-excited oscillator, exemplified bythemagnetron. 
 i'onversion Itss and noise-temperature ratio. The conversion loss of a mixer is defined as  available RF power L = - -- - -.  available IF power  it is a measure of the efficiency of the mixer in converting RF signal power into IF. 
 Later observations indicated even less backscatter from ice- covered Greenland areas. The backscattered energy from land is topography- dependent; as an example, a city in the central plains provides a larger echo than its surroundings. In contrast with such abrupt changes, the seascattering coeffi- cient a° for HF radio waves is fairly uniform; that is, it changes gradually with range and azimuth. 
 J. Burke and A. J. 
 This isthe most widely used method inthe voltage case when polarity reversal isinvolved. Nosatisfactory series switches exist foranalogous usewith resolved currents. Inthe second method ofcorrecting the sweep-origin difficulty, the positive and negative waveforms are“balanced” about thesweep origin either byintroducing aprecisely controlled negative waveform inthe primary circuit between sweeps, orbyarranging totrigger the trans- mitter automatically atthe precise time when the secondary current or voltage passes through zero. 
 (/2):/. 2!$!2   Óä°Çx THE RESONANT WAVE OR "RAGG FREQUENCY THEREFORE  THE RESONANT WAVE RESPONSES PEAK  AT o 4HE AMPLITUDE RANGE FOR EACH PLOT IS  D" 4HE NARROW PEAKS AT ZERO DOPPLER  FREQUENCY ARE DUE TO LAND IN AN ANTENNA SIDELOBE 4HE TARGET DOPPLER AND "RAGG LINE FREQUENCY COINCIDE AT A RADAR FREQUENCY OF  -(Z THE TARGET DOPPLER LIES BETWEEN THE "RAGG LINES FOR RADAR FREQUENCIES BELOW THAT FREQUENCY AND OUTSIDE THEM FOR &)'52%   -ULTIFREQUENCY (&372 DOPPLER SPECTRA SHOWING THE  DIFFERENT FREQUENCY DEPENDENCE OF I  TARGET AND II  CLUTTER SPECTRUM CHARAC 
 PULSE BASIS 0ULSE 
 31. T. Lee, “A study of spherical reflectors as wide angle scanning antennas,” IEEE Trans. 
 TAN      WHERE @  IS A TIME SIDELOBE LEVEL CONTROL FACTOR 7HEN @  IS ZERO  THE TANGENT 
 Kay, S.M.; Marple, S.L., Jr. Spectrum analysis-A modern perspective. Proc. 
 GAIN NOSE APERTURE    &)'52%  -&!2 %#- EXAMPLE . x°Ón  2!$!2 (!.$"//+  "ECAUSE THE ADVERSARY RADAR MAY ALSO BE A -&!2  THREAT TABLES WILL BE REQUIRED TO  CATEGORIZE THEM BY THEIR APPARENT STATISTICAL NATURE /LD STYLE MATCHING BY 02&  PULSE 
 We have seen how  scientists have had to revert to the use of the crystal  detector as a mixer in centimetre superhets. And the  early pioneers of radio, who remember Marconi’s ‘S’  spark signals from Cornwall to Newfoundland which  made history in radio communication, will smile on  investigating the spark-gap modulators used in many  microwave radar transmitters.  We have seen that radio-frequency oscillations can be  produced by a device such as the magnetron, but these  oscillations are of sine-wave form and must be modu-  lated by square-topped pulses of e.m.f. 
 SQUARED ANTENNA BEAM IT SOLVES ONE PROBLEM BUT CREATES ANOTHER IT ALSO DECREASES SENSITIVITY TO DESIRED TARGETS AT HIGH ELEVATION ANGLES WHERE THE ANTENNA GAIN IS LOW 4HE SOLUTION TO THIS PROBLEM IS TO BOOST THE ANTENNA GAIN AT HIGH ELEVATION ANGLES TO BE CONSIDERABLY HIGHER THAN THE REQUIRE 
 Moore, The University of Kansas (CHAPTER 12) David J. Murrow, General Electric Company (CHAPTER 20) William K. Saunders, formerly of Harry Diamond Laboratories (CHAPTER 14) Helmut E. 
 Thus the energy within the  pulse must not be too low. H the peak power is limited, a short pulse might not have enough  energy to make clutter, rather than receiver noise, dominate. Pulse compression (Sec. 
 The vital check onreceiver sensitivity yismade with a klystron noise source, whose output signal isintroduced via the r-f switch just described. The reliability and day-to-day reproducibility ofthetest setareexcellent, and having itbuilt inmakes aquick daily check onacent inuousl yoperated radar simple toperform. Over-all noise figures of9to12dbarecommonly maintained. 
 FRACTIONAL 
 It already covers more  than a quarter of the earth’s surface, and physicists who  . 150 HOW RADAR WORKS  are working to extend its range like to joke about the  time when with a transmitter at each pole and four  around the equator Loran will cover the world.  A reason for the great secrecy about Gee and similar  systems during the War was the obvious fear that if  the beacon transmitters were jammed by enemy signals  the navigational aid might become useless. 
 Studies show that three or perhaps  four colors is the optimum number for color display application.57•58 A particular four-color  display tested for air -traffic-control radar utilized yellow to present the aircraft data blocks,  g1 een for the area-sector map lines, red for navigation aids, and orange for showing  precipitation.61  The tricolor shadow-mask cathode-ray tube commonly used for color television has a  phosphor screen that consists of a series of three color dots. Although it may be well suited  for commercial TV, it is not always a good display for radar since its resolution is limited  by the size and spacing of the dots. Another color CRT of interest to radar is the penetration  color t11he using a multi-layer screen. 
 MTI RADAR  2.916x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 Comments.  The above procedure for determining true range and true radial veloc - ity has been described for a dwell of three CPIs and the assumption that each target  will have a return for each of the three CPIs. In practice, this assumption is not always  valid, and the actual implementation may choose, for example, to have the dwell con - sist of four or five CPIs, with the range and velocity determinations being based on  the best grouping of three returns. 
 pp. 407-4 1 1.  5 I. 
 While a discussion of ducting conditions upon EM wave  propagation is usually concerned with propagation beyond the normal horizon, duct - ing can have an effect within the horizon. Ducting can alter the normal lobe pattern  caused by the interference of the direct ray and the surface-reflected ray. The relative  phase between the direct and reflected path may be changed as well as the relative  amplitudes of the two rays. 
 SOUTH AND POORER RESOLUTION OF EAST 
 273-287. 22. Turyn, R., and J. 
 MTT-25, pp. 294-318, April, 1977.  100INTRODUCTION TORADAR SYSTEMS 57.Wadley,T.L.:Electronic Principles oftheTellurometer, Trans.SOl/thAfrican Inst.Elec.Engrs., vol.49,pp.143-161, May,1958;discussion, pp.161--172. 
 Anecho- box crystal-current meter isofvalue inmaking tuning adjustments. The remote power supply uses conventional electronic regulation. A simple RC-filter attheoscillator isolates thereflector electrode. 
 Additionally, its success in the two-scale-plus  model mentioned  above provides further credibility. Although scattering features have been introduced mainly in connection with  low-grazing-angle sea clutter (see Wetzel12 for a detailed discussion), there is evi - dence, as noted above, to believe that feature scattering operates at all grazing angles.  Considering the failure of scattering theories formulated as a GBVP to provide any  predictions beyond those in certain limiting-case approximations and the precarious  nature of the logical infrastructure of the Bragg hypothesis in microwave scattering  from a natural sea, it is quite possible that further careful consideration of the actual  scattering features present on the sea surface will improve our understanding of sea  clutter in the future. 
 Young, and L. A. Hyland. 
 l)aky. J. C .. 
 SKOLNIK (S=NATHANSONNRL-4FRNRL-4FR . corrections, the curves would show closer agreement. Nevertheless, it is clear that uncritical use of published clutter data could lead two radar systems design- ers to choose sea clutter estimates almost an order of magnitude apart for the same conditions. 
 TERM NAVIGATION IS PRO 
 van de Lindt, W. J.: Digital Techniques for Generating Synthetic Aperture Radar Images, 1Bhf Jorrr  of Research and Droelopmrnt, vol. 21, no. 
 17, pp. 41-44, February, 1974.  37. 
 Thelincofsight isthcstraight-line distance nctween radarandtargetthatisjusttangenttothesurfaceofthe earth.Thedistance between radarandtargetalongthelineofsightis do=/2kah,+/2ka"z (12.14) where"1'"z=heightsofradarantenna andtarget.respectively a=earth'sradius k=factordiscussed inSec.12.4,accounting forrefraction duetoauniform gra­ dientofrefractivity Thepointoftangency ofthelineofsightwiththeearthisthegeometrical, oroptical,IIori:::oll. Atopticalfrequencies ()::::::0)thefieldstrength withintheinterference region(thatis, between theradarandthegeometrical horizon) isessentially thesameasinfreespace.The fielddocsnotpenctrate heyondthehorizon. Thus,foropticalfrequencies orveryshortradar 10090 800001__--.-L -l-_---.-J ---l 30 40 50 60 70 Distonce, km50 2.0 1.0 (1) u0.5a Q V> (1) (1) .:=0.2 0 (lJ >0.1-- a (lJ "-005(".c +-- t:::ry<::>c'"(1)i:::"-002+-- <::>,n -<:: 'D ---.. 
 SIGNAL   % FIELDS 4HIS ALLOWS MUCH GREATER SIMPLICITY AND FLEXIBILITY ! TRIPLE 
 This requires format- ting operations on the data points to convert them to rectangular format.12'13 Imagery from synthetic aperture radars is shown in Figs. 21.5 and 21.6. These images were provided by the Environmental Research Institute of Michigan (ERIM). 
 The former is sometimes called the directivity, while the latter  is often simply called the gain. Both definitions are of interest to the radar systems engineer.  The directive gain is descriptive of the antenna pattern, but the power gain is more appropriate  for use in the radar equation. 
 Motion compensation to a fraction of a wavelength for platform maneuvers or devia - tions is applied to the data. A coarse two-dimensional FFT is performed followed by  space-time adaptive calculations, and filter weighting is applied to reject some clut - ter and jamming. High resolution doppler filtering is performed in a conventional  FFT,90,96,97 perhaps with DPCA clutter cancellation. 
 Phillips, D. E. Iglesias, and R. 
 (Ifnecessary it canbesurrounded byacylindrical radome.) Thechangeofbeamshapewithscananglecanbe minimized. ifdesired. byradiating cooperatively frommorethanoneplanarface.Asthebeam isscanned offbroadside, someofthetransmitter powercanbediverted tothefaceadjacent to thedirection ofscantoradiateenergyinthesamedirection.135Thebroadening ofthebeam duetotheforeshortening oftheplanaraperture iscompensated bythecooperative useofthe adjacent planaraperture. 
 D. Stuart, and C. K. 
 November, 1964.  82. Stegcn. 
 sirtnplitlg signal. By providing more than one sampling signal, multiple sirnultaneoi~s beanis  can be generated which can either be fixed or independently steered.  The local oscillator signals of Fig. 
 M. Novak, M. C. 
 then there are B/n possible decisions per second. The false-alarm probability is thus ti times as  great. This does not mean that there will be more false alarms, since it is the rate of detection-  decisions that is reduced rather than the average time between alarms. 
 119–136,  October 1984.  89. M. 
 Farquharson, E. Loew, W. C. 
 (From ~arlow,~~ Proc.  IRE.)  The clutter spectrum can also be expressed in terms of an rills clutter frequency spread cr,  in hertz or by the rms velocity spread a, in m/s.46 Thus Eq. (4.18) can be written  f 2A2 w(f) = wo exp (- <) 20, = Wo exp (- -)  8%  where Wo = (go 12, a, = 2a,/A, L = wavelength = c/ fo, and c = velocity of propagation. 
 ATED OVER TIME BY THE WEIGHTING OF THE ANTENNA PATTERN 4O EXTRACT 37( AND 73 FROM WAVEFORM DATA  FINELY TUNED ALGORITHMS HAVE BEEN  DEVELOPED AND VALIDATED AGAINST IN SITU BUOY MEASUREMENTS  &OR EXAMPLE  THE  4/0%8 +U BAND ALTIMETER MEASURES 37( TO WITHIN  o M UP TO MORE THAN  M AND  73 WITHIN  o MS UP TO MORE THAN  MS 4HESE FIGURES CORRESPOND TO AVERAGES OVER   SECOND  OR ABOUT  KM  ALONG THE SUB 
 DELAY CANCELER  AS A FUNCTION OF THE NUMBER OF HITS PER BEAMWIDTH 4HE ANTENNA PATTERN IS SIN X X    4HE COMPENSATION REQUIRED BY  $'P   CAN BE DETERMINED FROM A 4AYLORS SERIES EXPANSION OF  'P   )N THE PRE 
 91. D. Etter, A. 
 6.25. At low elevation angles, the maximum range is the critical requirement. Above the height-range limit intersection, altitude becomes the governing requirement, resulting in a cosecant-squared pattern shape. 
 Definitions.-The device that presents radar data inobservable form iscalled the indicator. Itisusually acathode-ray tube; alter- natively itmay bealoudspeaker ortelephone headset, aflashing light, amoving-coil meter, orapen-and-ink recorder. The cathode-ray tube (CRT) permits aninterpretation ofelectrical phenomena interms ofapicture painted onaphosphorescent screen bya sharply focused beam ofelectrons controlled inposition and intensity by electrical signals. 
 BAND FILTERS AT THE RECEIVER FRONT 
 Peake. and R. C. 
 In addition, the auxiliaries are placed sufficiently close to the phase center of the radar antenna to ensure that the samples of the interfer- ence which they obtain are statistically correlated with the radar jamming signal. It is also noted that as many auxiliary antennas are needed as there are jamming signals to be suppressed. In fact, at least N auxiliary patterns properly controlled in amplitude and phase are needed to force to zero the main-antenna receiving pattern in N given directions. 
 Wu: "Theory and Analysis of Phased Array Antennas," Wiley- lnterscience, New York, 1972.  J 5. Von Au lock, W. 
 The Teleran system has been worked out inmuch more detail than can bedescribed here. Enough has been saiclto indicate thefashion in which system planning, based always ontheneeds oftheuser, leads toa functionally simple but technically elaborate final result, embodying not only radar butalso beacons, television, aircraft instruments, and always— inescapable y—men.. CHAPTER 8 RADAR BEACONS BY L.A.TURNER Introduction. 
 REVERSAL POINTS 4HIS DOES NOT IMPACT ITS TIME SIDE 
 131-134 clutter-lock. 142 cluttermap,127 cohercnt rcfcrcncc. 385386 coho,1U5.141 delay-Iinccancelcr, 104-114 digitalprocessing. 
 Since the timing is controlled by a digital clock, the delay  can be made very stable, just as with digital processors. However, no A/D or D/A converters  are required as in digital systems. It has been claimed that such devices are more economical in  cost, consume less power, are of less size, and of greater reliability than digital processing. 
 65–72, March 1964. 18. G. 
 The analysis of radar detection can thus be regarded as a problem in statistical decision theory. Bistatic Radar Equation. The foregoing equations assume that the transmitting and receiving antennas are at the same location (monostatic radar). 
 At the output terminal of the designated component except where indicated byparentheses (at the input terminal of a nonlinear device). how excessively wide bandwidth can penalize dynamic range if the interference is wideband noise. Even more likely is an out-of-band source of strong interfer- ence (TV station or microwave communication link) which, if allowed to reach this point, can either overload the mixer or be converted to IF by one of the spu- rious responses of the mixer. 
 3. C. M. 
 WAVE STRUCTURE BASED ON LADDER GEOMETRY 4HE TUBE WEIGHS  KG AND CAN OPER 
 It was a complicated installation, including alternative antennas for high or low level operation and including manually operated tilt adjustment [ 1]. ASV Mk. X had a peak power of about 40 kW, with pulse lengths of 0.5, 1 or 2 μs and corresponding PRFs of 1010, 650 or 300 c/s, according to the selected range scale [ 3]. 
 Bracewell, J. H. Deuter, and J. 
 STATE  DEVICES OFFER THE FOLLOWING ADVANTAGES L .O HOT CATHODES ARE REQUIRED THEREFORE  THERE IS NO WARMUP DELAY  NO WASTED HEATER  POWER  AND VIRTUALLY NO LIMIT ON TRANSISTOR OPERATING LIFE 5NDER CERTAIN OPERATING CONDITIONS  THE PREDICTION OF THE MEDIAN TIME TO FAILURE -44&  FOR SOME 2& TRANSIS 
 TERER OF A RIGID 
 60, pp. 735--736, June,  1972.  41. 
 :  Figure 2.3 Envelope detector.  TilERADAR EQUATION 23 cnginccr, Itdcscrihes thccnvclopc ofthcnoiscoutputfromanarrowoandfilter (suchasJheIF filterinasuperheterodyne receiver). thecross-section l1uctuations ofcertaintypesofcomplex radartargets.andmanykindsofclutterandweather echoes.TheRayleigh densityfunction is (2.17) x~O 2x (X2 )I'(X)=2exp-i<x).v <x>av ThisisplottedinFig.2.2c.Theparameter xmightrepresent avoltage, and<x2>."themean,or average. 
 The Physical Optics (PO) method  is commonly employed for the most rigorous reflector analysis due to its accuracy.  It incorporates the field properties of the feed, and models the resultant fields from  the reflector, thus enabling the computation of the cross polarization properties.  Furthermore, the method is more accurate for feeds that are not at the focal point and  reflectors that are not parabolic. 
 FIELD TUBE THAT EMPLOYS  A MAGNETIC FIELD ORTHOGONAL TO THE ELECTRIC FIELD )T IS CAPABLE OF WIDE BANDWIDTH AND GENERALLY IS OF SMALLER SIZE AND  DOES NOT REQUIRE THE VERY HIGH VOLTAGES OF THE LINEAR 
 1.3are, ontheleft, the“tail” ofthetransmitted. 6 INTRODUCTION [SEC. 1.3 pulse leaking into the receiver, and ontheright, the echo signal from a radar target. 
 The rms error is  (10)1/2 .  lJJ = 1tr.a(Z£/ No)112 triangular pulse { 1 1.32)  The rms frequency error for a gaussian-shaped pulse is  1.18 B  {JJ = nr(2E/N0)112~ = 1.18(2£/N0)112 gaussian pulse (11.33)  The time-delay and frequency-error expressions obtained in this section apply for a single  observation. When more than one independent measurement is made, the resultant error may  be found by combining the errors in the usual manner for gaussian statistics; that is, the  variance (square of l,f or l>TR) of the combined observations is equal to 1/ N of the variance of a  single observation, where N is the number of independent observations. 
 By taking DF cross-bearings of at least  two stations an intersection of lines can be used to fix  position, just as if visual cross-plotting methods were  used. DF-ing by radio (using the frame-aerial direc-  tional properties, or the Bellini-Tosi crossed loop) thus . 144  . 
 Frequency is1300MHz(Lband)withlinear polarization. VV=vertical polarization. HH=horizontal polarization. 
 8. J. M. 
 Except forthe common local oscillator, the receiver isdivided into two portions, the AFC channel and the signal channel (see Fig. 12.17). The latter consists ofsixi-famplifier stages, adetector, and avideo stage. 
 CREATED FROM THE LINE   SIGNAL IN THE TIME DOMAIN AGAIN GIVE OR TAKE A SCALE FACTOR  AS ;LINE =    2E[;LINE =  EJO  F,/T]  FROM WHICH IT FOLLOWS THAT  ;LINE =    2E[! EJP E JO  F,/T]   ! 2E[EJO  F,/T   P ]    ! COSO  F,/T   P    !S A FINAL STEP THE BASEBAND ) AND 1 SIGNALS AFTER THE FILTERS ARE DIGITIZED BY !$#S AT  A  -(Z SAMPLING RATE  PRODUCING ) AND 1 OUTPUT SAMPLES OR  EQUIVALENTLY  COMPLEX  OUTPUT SAMPLES )   J1 4HE SLASH THROUGH THE OUTPUT OF THE !$# WITH A hv ABOVE IT IN &IGURE  INDI 
 ch02.indd   88 12/20/07   1:47:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 GATION AND THE AVAILABILITY OF UNOCCUPIED FREQUENCY CHANNELS DICTATE THAT THE RANGE RESOLUTION OF (& RADARS IS NOT NEARLY AS GOOD AS THAT OF MICROWAVE SYSTEMS 4HE (& TRANSMITTER HAS TO MAINTAIN STRINGENT CONTROL OF ITS RADIATED SIGNAL SPECTRUM SO AS TO AVOID INTERFERENCE TO OTHER USERS OF THE (& SPECTRUM ! SIMILA R CONSIDERATION APPLIES  TO MICROWAVE RADARS  BUT NOT TO THE EXTENT THAT IT DOES AT (& -ILITARY MICROWAVE RADARS LIKE TO HAVE AVAILABLE A WIDE SPECTRAL WIDTH FOR PURPOSES OF ELECTRONIC PROTECTION AND TO EXTRACT MORE DETAILED TARGET INFORMATION  BUT THE INCREASING DEMANDS OF CIVILIAN WIRE 
   30!#% 
 TANT CONSIDERATION AS EXCESSIVE PHASE VARIATION AS A FUNCTION OF ATTENUATION CAN HAVE A  DRAMATIC IMPACT ON RANGE SIDELOBES #LUTTER -AP !UTOMATIC 'AIN #ONTROL  )N SOME RADARS  MOUNTAIN OR URBAN CLUT 
 NOISE RATIO 3.2  AT TIME 4 IS GIVEN BY   CP PW 
 totheimaging ofrotating targels,14 especially themoonandplanets. ISFigure14.7showsa rigidhodyrotating atanangular speedof(l)rradians persecond, withtheaxisofrotation normaltothepaper.Thedoppler frequency associated withapointPonthebodylocateda distance,. fromtheaxisofrotation is . 
 PHASE COMPONENT  ) AND THE QUADRATURE COMPONENT  1  WHICH ARE CONVERTED TO THEIR  ANALOG EQUIVALENTS 4HESE PHASE SAMPLES MAY DEFINE THE BASEBAND  COMPONENTS OF THE  DESIRED WAVEFORM  OR THEY MAY DEFINE THE WAVEFORM COMPONENTS ON A LOW 
 LIKE PULSE 
 The first is a subcarrier band for the doppler intelligence which does not extendTRANSMITTER OUT DOPPLER LO . to dc but is centered at a frequency where either quartz or electromechanical filters have sufficient Q's to permit sharp filtering. (Values of 0.1 to 0.5 MHz or 1 to 5 MHz are suitable ranges for quartz filters; 0.1 to 0.5 MHz is proper for electromechanical filters.) The second alternative is quadrature detection.20 A suitable block diagram for this technique is shown in Fig. 
 GRATIONS 0ROPER CONVERGENCE OF THE FIELD SOLUTION AND RESULTING PATTERNS IS A FUNCTION OF THE GRID SIZE  AND THIS IS GENERALLY ACHIEVED AND VERIFIED BY INCREMENTALLY DECREASING THE GRID SIZE UNTIL THE SOLUTION STABILIZES !CHIEVING SUFFICIENT CONVERGENCE IN REFLECTOR 0/ COMPUTATIONS WITHIN REASONABLE COMPUTER RUN TIMES A FEW MINUTES OR LESS  IS RARELY A PROBLEM WITH MODERN COMPUTERS 'EOMETRICAL /PTICS '/  2EFLECTOR !NALYSIS  )NCLUDING '4$54$  4HERE ARE  A VARIETY OF '/ 
 2.7. At first glance, it might seem that  the signal-to-noise ratio required for detection is higher than that dictated by intuition, even  for a probability of detection of 0.50. One might be inclined to say that so long as the signal is  greater than noise, detection should be accomplished. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars.  SPACE-BASED REMOTE SENSING RADARS  18.516x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 space-based SAR standards. 
 WAY PROPAGATION LOSS BETWEEN THE JAMMER AND THE RADAR 7ITH SIDELOBE JAMMING  THE RADAR DESIGNER CAN REDUCE THE JAMMER ADVANTAGE BY LOW SIDELOBE DESIGN COUPLED WITH THE USE OF  SIDELOBE CANCELLATION TECHNIQUES 7ITH  MAIN 
 36).   Stimson5 provides  a detailed explanation for this result (pp. 416–417). 
 The target islocated onthe full-range A-scope, and therange interval covered bytheexpanded A-scope adjusted toinclude the target. Aportion ofthe sweep ofthe expanded A-scope isdeflected downward toform a“ditch” (Fig. 6.2c). 
 ING REQUIREMENTS OCCUR BECAUSE OF THEIR HIGHER CONVERSION EFFICIENCY 4HEY ARE ALSO SAID TO HAVE HIGHER RELIABILITY WITH LONGER COMPONENT LIFE 4HE ABILITY OF THE SOLID 
 TOR CURRENT MODULATED BY THE CURRENT FLOWING BETWEEN THE BASE 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°£x 4HE HIGH 
 5-103, January, 1955.  39. Fox, A. 
 PASS AND HIGH 
 The output of the  optical processor is a maplike photographic film of the terrain, as in Fig. 14.4. The SAR  produces images without the slant-range distortion that occurs with the photographic camera. 
 The amplitude measurement is  used (along with ToA) for deriving the scan pattern of the emitter.9 The classification of radar interception systems is based on the type of represen - tation they provide of the electronic environment. A radar warning receiver (RWR)  in an airborne installation provides alerts of the presence of threats such as radar on  a missile, supplying the relative bearing on a cockpit-based display. Search radars  are not the primary target for these systems, though range advantage due to one-way  propagation with respect to two-way propagation allows radar interception at farther  range than own platform detection. 
 Even if only one target were present,  the noise from the other range cells that do not contain the target .vill interfere with the desired  target signal. The result is a reduction in sensitivity due to a collapsing loss (Sec. 2.12). 
   
 Nineteen of these radars  were installed on major ships of the fleet by 1941.  The United States Army Signal Corps also maintained an interest in radar during the  early 1930s. 7 The beginning of serious Signal Corps work in pulse radar apparently resulted  from a visit to NRL in January, 1936. 
 B., 29  Loran, 129, 149-150  Lovell, A. C., 28  MAGNETRON, 27, 117 et seg.  Modulator (Mod), 49 et seg. 
 PROCESSING TECHNOLOGY HAVE ENABLED A WIDER VARIETY OF WAVEFORM IMPLEMENTATIONS &OR EXAMPLE  RADAR SYSTEMS ARE NO LONGER LIMITED TO THE ,&- WAVEFORM INSTEAD  RADAR SYSTEM CAPABILITIES CAN BE EXTENDE D TO TAKE ADVANTAGE  OF THE MORE COMPLEX PROCESSING ASSOCIATED WITH THE NONLINEAR &- WAVEFORM !.403 
 Linear velocity was simulated using the Matlab peaks function, which can satisfy both positive and negative distribution characteristics of displacement [ 35]. There were 200 high coherence points and 10 interferograms generated in the simulation. With the known SAR sensor parameters (TerraSAR-X Stripmap data with descent orbital mode was used),including spatial and temporal baselines of each interferometric pair, values of all the parameters for over 200 high coherence pixels could be detected from the simulated ﬁeld as true values in the following validation. 
 Kelleher. K. S.: Designing Dielectric Microwave Lenses, Electronics, vol. 
 19, pp. 269–290, 1986. 47. 
    
 The beat-frequency amplifier need only be wide enough to pass the  received signal energy, thus reducing the amount of noise with which the signal must com pctc.  The frequency excursion is maintained by a servomechanism to that value which permits the  beat frequency to fall within the passband of the narrow filter. The value of the frequency  excursion is then a measure of the altitude and may be substituted into Eq. 
 EFFECTS CHART  (   HIGH INPUT FREQUENCY  ,   LOW  INPUT FREQUENCY .   2!$!2 2%#%)6%23   È°£Î 3EVEN PARTICULARLY USEFUL REGIONS HAVE BEEN OUTLINED ON THE CHA RT 5SE OF THE CHART  IS ILLUSTRATED BY MEANS OF THE REGION MARKED !  WHICH REPRESENTS THE WIDEST AVAILABLE  SPURIOUS 
 RADC-TDR-64-225, vol. I,  pp. 17 38. 
 5.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 A Kalman filter (a recursive filter that adaptively combines models of target mea - surements and of errors10) is employed to provide a better estimate of aircraft velocity.  Although this procedure can be performed over land or water, sea currents make over- water measurements far less accurate. This velocity measurement provides in-flight  transfer alignment of the various inertial platforms (aircraft, weapons, and radar). 
 1968.  63. Albersheim. 
 Poor  cd  ‘xqpuaddy  say; Pda  WIUATO)  wow  y  APPS  fo  Aaparzy  ayy  fo  Asapanos  Aq AVIASICE  AONVY  Vo  AMAR  SI  SLLW  Id  . ETI  FroZr  ty  ‘xipteddy  vag] PIUISIA  JYdlatfod  unody  “Aajsinipy  aly  ayy  fo  dsajanoa  Ay dVW  FOUL  GNV  NAMWOS  UVAVA  :WALSAS  SGH  ‘IT  ALVId ef aonn0siy  apers  dey  Qu ok  os  Bo  peony  &  . CENTIMETRIC TECHNIQUE It3  The magnetron was a spur to other physicists and  technicians, and it was supplemented by an equally  novel receiving valve evolved by Dr R. 
 M. Rosen, “Evaluation  of EarthRadar unexploded ordnance testing at Fort A.P. Hill, Virginia,” IEEE Aerospace and  Electronics Systems Magazine , vol. 
 pp. 80-107. January. 
 (The continumum between the two spectral  lines is determined by second-order scattering from sets of waves that form corner  retlectors.24) If land clutter is present in the radar resolution cell along with sea clutter, or if it  enters the radar via the antenna sidelobes, there will be a spectral component at zero frequency  which can degrade the usefulness of this measurement. When the sea is saturated, which is not  111111s11.1I for those waler wavelengths resonant with HF wavelengths. theory rredicts. 
 When the sites surround the target, for example, when positioned  around the launch site of a ballistic missile, a remains relatively large during the  missile’s launch phase, yielding precise altitude estimates. When the sites are some  distance from the target, for example, when conducting air or missile surveillance, a  is  small, yielding poor altitude estimates. Both bistatic and multistatic radars can potentially achieve even better location  accuracy by using narrow-band doppler tracking under the following conditions:  (1) When integrating doppler data, initial conditions (the pesky constant of integra - tion) can be established with sufficient accuracy. 
 Scattering from any distributed target involves the product of the transmitting and receiving system footprints integrated over the target. These footprints cover exactly the same area for a monostatic radar and will depend on the pulse and beam widths, the range, and the grazing angle. If the footprints are assumed to be of the cookie-cutter type (constant amplitude falling sharply to zero at the half-power points), then the relation between the actual radar clutter cross section ac, as inferred from the received power via the radar equation, and the NRCS a° is given by a° = vJAf (13.7) where for a radar with an antenna beamwidth B and rectangular pulse of length T, viewing the surface at range R and grazing angle 0, the area Af is either Af = Tr(BR)2/4sm 0 (13.8) for beam-limited conditions [e.g., continuous-wave (CW) or long-pulse radar at high grazing angles] or Af = (c>r/2)BR/cos 0 (13.9) for pulse-width-limited conditions (e.g., short-pulse radar at low grazing angles). 
 Noclaimismadethatthe rationale givenforeachcharacteristic wasthatwhichinnuenced theoriginal specifications for thisradar.Thebriefdiscussion hereissimplymeanttoconveysomeofthegeneralphilosophy thatmightenterintoradardesign. TheARSR-3 hasaninstrumented rangeof200nmi,andisrequired todetecta 2 m2 cross-section targetwithasingle-scan probability ofdetection of0.8andafalsealarmproba­ bilityof10-6.Thegreatertheradarrangethefewerthenumber ofradarsrequired tocovera spccifled area.Ontheotherhand.theradarscannotbeplacedtoofarapartsincethecurvature oftheearthwilllimittheminimum altitude alwhichtargetscanbeseen.Forexample. at 200nmi.alltargetsbelowXkmaltitude areheneath theradarlineofsightandnormally wouldnothedetected. 
 ATION ACHIEVES   0$ WITH  D" LESS TOTAL SIGNAL POWER THAN SIMPLEX !SSUMPTIONS  MADE IN DERIVING &IGURE  ARE  2ETURNS ON THE TWO FREQUENCIES ARE ADDED IN VOLTAGE OR POWER PRIOR TO THE DETECTION  DECISION RATHER THAN BEING SUBJECTED TO INDIVIDUAL DETECTION DECISIONS  3EPARATION OF THE TWO FREQUENCIES IS SUFFICIENT TO MAKE THEIR 3WERLING  FLUCTUA 
 3.2) shows that there are certain choices of frequency ratio that provide spurious-free frequency bands, approximately 10 percent of the intermediate frequency in width. By the use of a high first IF, one can eliminate the image problem and provide a wide tuning band free of spurious effects. Filtering prior to the mixer remains important, however, be- cause the neighboring spurious responses are of relatively low order and may produce strong outputs from the mixer. 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°Î£-ANEUVER -ODEL 1 
 16. Zhu, D.; Jiang, R.; Mao, X.; Zhu, Z. Multi-Subaperture PGA for SAR autofocusing. 
 Tukey, “An Algorithm for the machine calculation of complex Fourier series,”  Mathematics of Computation , vol. 19, no. 90, pp. 
 Reeves, and F. E. Jones. 
 PATTERN LOSS AT ANGLE  P, ! SIMILAR RANGE 
 Bipolar video signals are separated into to channels, from which one is delayed by the  pulse duration T = 1/f p.  Then both are subtracted.  The procedure is illustrated in Figure 8.9. 
 TANEOUSLY WITH THE '-4)v 4HE AUTHORS ALSO MAKE CLEAR THAT 'LOBAL 0OSITIONING 3YSTEM '03  INPUTS WERE ESSENTIAL TO THEIR ACCURATE LOCATION OF TARGETS FIXED TAR 
 At the same time resear ch work became heavily promoted and supported in many  countries, like the USA, England, France and last, but not least, Germany.  . Radar System Engineering  Chapter 1 – History of Radar Technology  2        Figure 1.1  Cover page of Hülsmeyer’s patent specification  . 
 MATION OCCURS RIGHT AFTER THE INTEGRATOR SECTION AND BEFORE THE COMB SECTION 4HE DELAY IN THE COMB FILTER BECOMES A VALUE  .S  WHERE  . IS EQUAL TO  $2 4HIS ALLOWS THE COMB  SECTION TO OPERATE AT THE DECIMATED SAMPLE RATE  WHICH MAKES IT SIMPLER TO IMPLEMENT $UE TO THIS SIMPLIFICATION  #)# DECIMATORS ARE GENERALLY IMPLEMENTED IN THIS FORM &)'52%   A  #)# DECIMATION FILTER AND B  #)# INTERPOLATION FILTER          
    .   !)2"/2.% -4)  Î°Óx WHERE 2R   %[R Rg] 4HE DESIRED SIGNAL   D  CAN BE EXPRESSED IN TERMS OF  S  THE SIGNAL  VECTOR OF A TARGET LOCATED IN THE MAIN BEAM  AND  B  THE UNADAPTED BEAM WEIGHT VECTOR  D   Bg S 4HIS IS THEN SUBSTITUTED INTO %Q   }W22 BRS 
 4. Bennett, W. R.: Methods of Solving Noise Problems, Proc. 
 PROCESSED COMPONENTS LEAD TO A REDUCED NUMBER OF  PARTS FROM THE RELIABILITY STANDPOINT AND HENCE TO INCREASED OPERATING LIFETIMES L )NCREASED REPRODUCIBILITY  #IRCUITRY THAT IS BATCH 
 ING THE AMBIENT 2&) ENVIRONMENT DESCRIBED BELOW  THE NOISE SPECTRAL DENSITY  K4S    
 Dinger, E. Nelson, S. Anderson, F. 
 But for 'maximum efficiency with CW radar, the reduction in  -n. h sensitivity caused by the simple doppler.r&iver with zero IF, cannot be tolerated.  or ? 4.+<qLJX".\. 
 OSCILLATOR TO DIFFERENTIATE IT FROM A  GYRO 
 5.5 Microwave Field-Effect Transistors (FETs)  .........  5.9  Millimeter-Wave Solid-State Power Sources  ......  5.11  5.3 Solid-State Microwave Design  ................................ 
 QQ P     AND THE CORRESPONDING RADIAL VELOCITY IS   } VF IDI L     )N  MOST CASES OF INTEREST  THE ACCURACY OF THIS ESTIMATE OF DOPPLER FREQUENCY IS AS  GOOD AS THE MAXIMUM LIKELIHOOD PROCEDURE %XPRESSED IN TERMS OF THE NUMERATOR OF  %Q   WHICH WILL BE DENOTED BY  K  A SIMULATION OF THE PHASE 
 The signal-to-noise ratios of Fig. 2. 7 apply to a  single radar pulse. 
 Afirst-order balance oftransconductance changes due to heater voltage fluctuations will result ifthe same number ofamplifying tubes isused ineach channel. Pentodes with high mutual conductance frequently exhibit small sudden changes ingain asaresult ofeither heat- ingorvibration. The gains oftheindividual channels can bestabilized through feedback ofbias derived bydetection ofthe carrier level. 
 y« = *,• - *2*.--i (8-io) and % = ys-i + ktfi-i (8.11) where Jt1 is the input, y,- is the intermediate calculation, zt is the output, and ^1 and k2 are the two feedback values. The values12'13 which maximize PD are given by *, = 2 exp (-W/Vl - £2) cos (oyr) (8.12) and *2 = exp (-2?<vr/Vl - £2) (8.13) where £ = 0.63, MO^T = 2.2, and TV is the number of pulses between the 3-dB points of the antenna. With this rather simple device a weighting pattern sim- ilar to the antenna pattern can be obtained. 
 DEFINED EXCLUSION ZONES !LGORITHMS FOR PREVENTING PLOTS FROM BEING FORMED ON TYPI 
 If the receiver is not the exact matched filter for the transmitted waveform, a loss in  signal-to-noise ratio will occur. Examples are given in Table 10.1. A typical value of loss for a  nonmatched receiver might be about 1 dB. 
 To further analyze the inﬂuence of wind speed on SAR eddy imaging, ΔσandΔσrof Figure 16were calculated. The results are shown in Figure 17. L-, S-, and X-band were also considered. 
 Meteorol. Soc., vol. 63, pp. 
 An experimental installation was made on a Whitley with very encouraging results, detecting submarines viewed broadside at 20 miles from 2000 ft. However, the minimum range, mainly determined by the extent of the sea return, could be 4 or 5miles at this height. The experimental Whitley arrived at St Athan on 17 August 1940 and RAE and 32 MU were tasked with installing LRASV on 5 Whitleys, later increased to arequirement for 50. 
 1957.  20. Kalmus, H. 
 Therefore n~8~ ) bO=(2E/No)l/2 (11.42b. EXTRAC110N 01: INFORMATION AND WAVEFORM DESIGN 411  where the units of 60 are the same as those of 0,. The relative error (6e/eB) is a function of  EJN, only. 
 33. J. L. 
 TION SYSTEMATIC ERRORS  BECOME SIGNIFICANT )N PRACTICE  PEAK SIDELOBE LEVELS AS LOW AS  
 To make available more independent clutter echoes, the antenna rotation rate can be  in~reased.~'.~~ If, for example, the radar antenna has a 2" beamwidth, a pulse repetition  frequency of 3600 Hz, and a 20 rpm rotation rate, there will be 60 pulses returned from a  target on each scan of the antenna.There is little integration improvement obtained from these  60 pulses since they occur within a time (& s) comparable to the decorrelation time for  X-band sea clutter. If the antenna rotation rate is speeded II~ to 600 rpm, there will be 2  pulses received during a scan past a target. (There should be at least 2 pulses per scan rather  than one, in order to avoid a large scanning loss.) On thc next scan, one-tc~~tll sccoucl later, two  additional pulses are received that are decorrelated from the previous two pulses so that an  integration improvement can be obtained. 
 Figure 12.24 shows an example of this variation. No theory gives exactly this result, but nearly all measurements fit such a model closely, and the model approximates most theoretical curves well over the relevant regions. This simple result means that simple clutter models may be developed and used although more complex models may be necessary for some remote-sensing applications. 
 ATION EVEN WHEN NOT CONTROLLED BY THE BISTATIC RADAR 7HEN THE TRANSMITTER OF OPPOR 
 Since absolute height accuracy is not required, geodetic radar altimeters can be  relatively basic instruments.88 They do not need to compensate for propagation delays;  hence they need only one frequency, and they do not necessarily need a water vapor  radiometer (WVR). Indeed, a simple instrument is preferred; it has been shown that  efforts to correct for path delays usually add noise to slope estimates.89 Geodetic mea - surements provided by the Geosat and ERS-1 (both single-frequency altimeters with  no WVR) furnished the best resolution oceanic geodesy and bathymetry available up  through at least 2010 for the open ocean. Their resulting bathymetric resolution is lim - ited to about 25 km north-south and poorer resolution of east-west slope components. 
 AII cxnnlplc of propag;~tion ill elevated ducts is foi~nd in tile " tr,adewitid  regiorl " l>etweeri [lie rnidoccaii. Iiigil-pressure cells and tlie equatorial doldrums. 'I'wo sucli  tradewir~d areas that have been stildied lie between Brazil and the Ascension islandsz9 and  t,etween Soutl~err~ Califor~~ia and t iawaii." The tradewind ternperature itlversio~i is usually  foi~tid over tile caster11 portions of the tropical oceans. 
 LINEARITIES  ADDED NOISE  ETC   THE SPECIFIED %./" OF AN !$# IS ALWAYS LESS THAN THE NUMBER OF BITS IT PROVIDES &OR EXAMPLE  A  
 R is the range to the clutter (meters) and c is the speed of propagation. It should be noted that for land clutter s 0 can vary considerably from one resolu - tion cell to the next. A typical distribution of s 0, taken from Barton,12 is shown in  Figure 2.16. 
 (13.8) can be  selected similar lo that for signal-to-noise ratio as described in Chap. 2. (It will be seen in  Sec. 
 L.=effective shunt orself-inductance (input inductance with open circuit secondary). R.=resistance due toeddy current iniron and tohysteresis. Agood pulse transformer design attempts tomaximize the shunt inductance L.and minimize the leakage inductance L1.Inaddition, undesirable oscillations arising from theseries resonant circuits shown at. 
 SYNCHRONOUS  DAWN 
 Fixed tuning isemployed inthis replace- able subunit. The i-fbandwidth ismade considerably wider than that IByL.Y,Beers andR.L.Sinsheimer.. #jlfr220I (-.—. 
 Thematerial inthisbookhasbeenusedasthebasisforagraduate courseinradartaught bytheauthorattheJohnsHopkins 'University Evening College and,beforethat,atseveral otherinstitutions. Thiscourseisdifferent fromthoseusuallyfoundinmostgraduate electrical engineering programs. Typical EEcourses covertopicsrelatedtocircuits, components, de­ vices,andtechniques thatmightmakeupanelectrical orelectronic system;butseldomisthe studentexposed tothesystemitself.Itisthesystemapplication (whether radar,communica­ tions,navigation, control, information processing, orenergy)thatistheraisond'ctreforthe electrical engineer. 
 2&v RADAR  4HE VERSION FOR #HANDRAYAAN 
 BEAM PATTERN 4HE CONTINUOUS LINE IS THE 3).2 FOR THE ADAPTIVE IRREGULAR SUB 
 Three main approaches—adaptive threshold, nonparamet - ric detectors, and clutter maps—have been used to reduce the false-alarm problem.  Adaptive thresholding and nonparametric detectors assume that the samples in the  range cells surrounding the test cell (called reference cells ) are independent and identi - cally distributed. Furthermore, it is usually assumed that the time samples are indepen - dent. 
 Electronic phase steering, instead of frequency scanning, in the  3D air-sur,veillance radar is generally more expensive, but allows the use of the frequency  domain for purposes other than beam steering. The linear array configuration is also used  to generate multiple, contiguous fixed beams (stacked beams) for 3D radar. Another  application is to use either phase- or frequency-steering in a stationary linear array to  steer the beam in one angular coordinate, as for the GCA radar. 
 U. Mishra, P. Parikh, and Y . 
 Pulsemodulation. Theklystron amplifier maybepulsedbyturningonandoffthebeam accelerating voltage,similartoplatemoduiation ofatriodeormagnetron. Themodulator in thiscasemustbecapableofhandling thefullpowerofthebeam.Whenthetubeismodulated bypulsingtheRFinputsignal,thebeamcurrentmustbeturnedonandoff;otherwise beam powerwillbedissipated tonousefulpurpose inthecollector intheinterval between RF pulses,andtheefficiency ofthetubewillbelow.Acommon methodforpulsingthebeamofa klystron iswithanelectrode intheelectron gunthatcontrols theklystron-beam current.This. 
 Then, the techniques are introduced according to their use in the various sections of radar, namely, an- tenna, transmitter, receiver, and signal processing. A key role is also played by those ECCM techniques which cannot be classified as electronic, such as human factors, methods of radar operation, and radar deployment tactics (Sec. 9.10). 
 23.9 Tail-mounted doppler radar antenna on the P-3 research and reconnaissance aircraft operated by the National Oceanic and Atmospheric Administration (NOAA). can measure only two components of vector air motion, the assumption of mass continuity is invoked. The equation of continuity (V-V = O) is used to obtain the third-dimensional component, where V is the vector air motion. 
 Targets at other time delays, or ranges, might be found by varying  T,. However. this requires a longer search time. 
 11.3.—Broadband stub support. support. and causes noreflection. 
 GATION AND THE PRECEDING DISCUSSION OF SKYWAVE SYSTEMS  IT SUFFICES HERE TO ADDRESS THE MAIN FEATURES OF (& SURFACE WAVE OR GROUND WAVE  RADAR (&372  (&372 SYSTEMS TEND TO FALL INTO TWO CATEGORIES I  LOW 
 E. Machol in 1952.34 . Bistatic radars received renewed interest in the 1970s and 1980s as counters to retrodirective jammers and attacks by antiradiation missiles (ARMs). 
 1200–1201, July 1959. 76. K. 
 HH      WHERE   H 
 The radar mass is 100 kg (including the reflector  and feeds); satellite dry mass including the radar is ∼300 kg, which at the time set the  standard as the smallest SAR satellite in Earth orbit. The power subsystem delivers  up to 1.6 kW during imaging operations. The spacecraft orbit is 143 ° inclination,  ∼550 km altitude, 36-day repeat period. 
 The 12-cm wavelength of the Magellan Venus radar (reviewed  in Section 18.4) was chosen in response to the trade-off between propagation through  Venus’ very dense atmosphere (for which longer wavelengths would be better) and  synthetic aperture radar system considerations (for which shorter wavelengths would  be better). Propagation speed is retarded along the path length from an ocean-viewing  altimeter to the Earth by a very small fraction of the speed of light, but sufficient nev - ertheless to impose range measurement errors of many meters. These errors must be  estimated and compensated before the required cm-level accuracy can be achieved,  as summarized in Section 18.3. 
 AND 
 Ship -based radar provide  surface -to- surface and surface -to-air observation. Airborne radar is  utilized for threat detection, surveillance, mapping, and  altitude determination. Finally, missile radars are used for  tracking and guidance. 
 Prop. , vol. 47, pp. 
 Also, assum - ing the ambient RFI environment described below, the noise spectral density kTs =  −179 dBW/Hz; thus, Cdp = 88 dB. Combinations of earth masking, antenna shielding, spatial cancellation, and spec - tral cancellation can be used to achieve the required direct-path attenuation. A brute- force remedy is to physically block the transmit signal from the receiver with a shroud  or structure, or if coverage allows, over-the-horizon separation. 
 BASED COMMUNICATIONS APPLICATIONS 3EE WWWHARRISCOM FOR  MORE DETAILS "ECAUSE MOST REFLECTOR DESIGNS HAVE AT BEST LIMITED ELECTRONIC SCAN CAPABILITY  A  GIMBAL IS TYPICALLY NEEDED TO EXTEND THE MECHANICAL  &/6 FOR THE RADAR 4HE KEY FACTORS OR SPECIFICATIONS THAT TYPICALLY DRIVE THE DESIGN OR PROCUREMENT OF THE GIMBAL ARE SCAN RATE  SLEW REQUIREMENTS  ACCELERATIONDECELERATION REQUIREMENTS  TORQUE AND LOAD REFLECTOR MASS  REQUIREMENTS  POWER REQUIREMENTS  ETC )T IS IMPORTANT FOR THE RADAR SYSTEM ENGINEER TO UNDERSTAND THESE FACTORS AND ASSOCIATED PRACTICAL GIMBAL DESIGN LIMITS %NVIRONMENTAL &ACTORS AND #ONSIDERATIONS  4HE IMPACT OF ENVIRONMENTAL FAC 
 CULATED BECAUSE A CHANGE IN FREQUENCY NO LONGER PRODUCES A TRANSLATED BEAM BUT RATHER A BROADER BEAM COMPOSED OF TWO TRANSLATED BEAMS 3PACE &EED 4HE SPACE OPTICAL  FEED CAN BE CONSIDERED TO BE SOMEWHAT BETWEEN  A PARALLEL FEED AND A CENTER 
 The servosystem  filters out all frequencies outside the frequency range between the scan rate plus the  servo bandwidth and the scan rate minus the servo bandwidth, and an angle sensitivity  constant that converts rms modulation to rms angle error. An equation using this relation to calculate rms noise in scanning and lobing-type  tracking radars caused by high-frequency amplitude noise22 is  σθβsB sskA f =2( )  (9.5) ch09.indd   29 12/15/07   6:07:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Both amplitude and phase quantiza - tion lead to discontinuities that may be periodic and give rise to quantization lobes  that  are similar to grating lobes. Amplitude or phase errors that vary cosinusoidally may be analyzed simply after  Brown.77 Figure 13.21 a shows an original amplitude distribution F(x) disturbed by a  cosinusoidal ripple q cos (2p x/s), giving a new distribution F ′ (x) such that  ′= + = +F x F x qFxx s F xqF x ej x s( ) ( ) ( )cos ( ) ( )(2 22π π/ )) ( )( )+ −F x ej x s 2π/  When the beam is scanned to q0, the quantization lobes occur at an angle q1,  where  sin s inq q1 01= ±s/λ  The gain of the aperture varies as cos q, and the relative amplitude of the quanti - zation lobe is modified by the factor (cos ) /(cos ). q q1 0 Figure 13.21 b–g shows the  effects of various other periodic aperture modulations.FIGURE 13.20  Antisymmetrically phased array ch13.indd   35 12/17/07   2:40:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Mengel, J. T.: Tracking the Earth Satellite and Data Transmission by Radio, Proc. I RE, vol. 
 2. Basic Procedures of Moving Ship Refocusing in SAR Images Moving ships are regularly blurred and defocused in SAR images due to the translation motion with respect to the scene center. ISAR technology is a common method to form well-focused images, but it has two basic problems. 
 J.: Feed Support Blockage Loss in Parabolic Antennas, Microwave J., vol. 11. pp. 
 The ratio of the tneali to tlte  median value of a is exp (si/2). Tllere is no theoretical model of target scattering that leads to  the log-normal distribution, although it has been suggested that echoes from some satellite  bodies, ships, cylinders. plates, and arrays can be approximated by a log-normal probability  di~tribution.~~.~"  Figure 2.25 is a comparison of the several distribution models for a false alarm number of  106 when all pulses during a scan are perfectly correlated but with pulses in successive scans  itldependent (scan-to-scar1 fluctuation). 
 However, spuri - ous IF frequencies of 0.34 (4 H – 6L) and 0.4 (3 H – 4L) are generated at the extremes  of the RF passband. Any extension of the instantaneous RF bandwidth will produce  overlapping IF frequencies, a condition that cannot be corrected by IF filtering. The  4H – 6L and 3 H – 4L spurious frequencies, like all spurious IF frequencies, arise from  cubic or higher-order intermodulation. 
 ANGLE WEDGE  SOLUTION 4HIS GENERATED A NEW SET OF DIFFRACTION COEFFICIENTS THAT RETAINED ONLY THE EDGE TERMS  THEREFORE EXCLUDING ANY SURFACE TERMS 5FIMTSEVS 0 4$ COEFFICIENTS WERE  WELL BEHAVED IN ALMOST ALL DIRECTIONS IN SPACE  BUT SUFFERED ONE DISADVANTAGE IN ORDER TO CALCULATE THE 2#3 OF AN ARBITRARY EDGED BODY  ONE HAD TO SUM ALL THE 04$ EDGE CONTRIBUTIONS   PLUS ALL THE 0/ AND '/ SURFACE CONTRIBUTIONS (OWEVER  THE PROCEDURE  IS VIABLE AND HAS BEEN WELL DOCUMENTED  )NCREMENTAL ,ENGTH $IFFRACTION #OEFFICIENT  '4$ AND 04$ ARE BOTH BASED ON  THE EXACT SOLUTION OF THE TWO 
 52 The tritium is  in compound form as a tritide film. The replacement of the keep-alive by radioactive tritium  eliminates the excess noise of the keep-alive and increases the life of the TR by an ·order of  magnitude. Since a tritium TR needs no active voltages, a mechanical shutter is not required to  protect the receiver from nearby transmissions when the radar is turned off. 
 ING FROM n KM LONG AND n KM WIDE !  
 3.17. Leakage introduced by  the circulator and by reflections from the antenna are at close range and thus are attenuated by  the J, factor.  A plot of J,(D) as a function of distance is shown in Fig. 
 lc. The_ difference in amplitude  hetween the voltages obtained in the two switched positions is a measure of the angular  displacement of the target from the switching axis. The sign of the difference determines the . 
 54. W. B. 
 4.9b has the same frequency-response character-  istic as the double-delay-line canceler. The operation of the device is as follows. A signal f (t) is  inserted into the adder along with the signal from the preceding pulse period, with its ampli-  tude weightkd by the factor - 2, plus the signal from two pulse periods previous. 
 T., 27,  112, II3  Range-markers, electrical, IOI  Ratcliffe, J. A., 29  » Reeves, A. H., 29 (gerry  3 a,  af. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.8  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 to implement. They have been developed and deployed in the past to provide elevation-   angle scanning in combination with mechanical horizontal rotation for 3D radars. 
 InFig. 3.20 the diffuse bright rings atthe center ofthe picture are theresult ofanimperfectly shaped antenna pattern. These intensifica- tion ringsl make itdifficult todistinguish irregularities onthe ground, but they are not asobjectionable asthe black rings or“holes” which would have appeared iftheantenna pattern, instead ofbeing toostrong, had been tooweak inthose regions. 
 A waveform that yields  good resolution will also yield good accuracy, but the reverse is not always so. 420 INTRODUCTION TO RADAR SYSTEMS  A continuous waveform (a single pulse) produces an ambiguity diagram with a single  peak. A discontinuous waveform can result in peaks in the ambiguity diagram at other values  of TR,fJ, The pulse train (Fig. 
 However, the large vertical. apertures to achieve such a capability are quite  costly, so that HF OTH radars seldonl have as large a vertical aperture, or as narrow an  elevation beamwidth, as might be desired.  The propagation factor (F,), receiver noise (No), and coherent integration time (T,) of  Eq. 
 TO 
 PRESSED BY THE BLANKING LOGIC )T IS ASSUMED THAT THE GAIN  ' ! OF THE AUXILIARY ANTENNA  IS HIGHER THAN THE MAXIMUM GAIN 'SL OF THE SIDELOBES OF THE RADAR ANTENNA 4HE PERFORMANCE OF THE 3," MAY BE ANALYZED BY LOOKING AT THE DIFFERENT OUTCOMES  OBTAINED AS A CONSEQUENCE OF THE PAIR  U  V  OF THE PROCESSED SIGNALS SEE &IGURE  B  &)'52% A  -AIN AND AUXILIARY ANTENNA PATTERNS FOR THE 3,"  AFTER  , -AISEL Ú )%%%   &)'52% B  3CHEME OF SIDELOBE 
 (13.6). This means there is likely to be greater  variation in the maximum range of a clutter-dominated radar than a noise-dominated radar.  For example, if the target cross section in Eq. 
 TERED SIGNALS &URTHERMORE  ALTHOUGH THE INCREASED RATE OF DECAY OF THE SURFACE WAVE AT HIGHER FREQUENCIES IMPOSES A LIMIT ON THE RANGE OF FREQUENCIES THAT MIGHT BE USED TO DETECT A TARGET AT A GIVEN RANGE  THE SITUATION IS BY NO MEANS  AS RESTRICTIVE AS FOR SKY 
 The optimum weight vector W is determined by minimizing the mean square prediction error which equals the out- put residual power: PZ = E { \Z\2} = E{\VM - W7VI2J (9.2) where Z is the system output. It is found that the following fundamental equation applies:27 W = JJiM-1R (9.3) where |x is an arbitrary constant value. The benefit of using the SLC can be measured by introducing the jammer can- cellation ratio (JCR), defined as the ratio of the output noise power without and with the SLC: ™ E{lVMl2} E[W^}JCR = = (9 4) E{\VM - W7VI2J E{\VM\2} - R7M-1R*TARGETSIGNALJAMMERS SIDELOBESAUXILIARY ARRAY ADAPTIVESYSTEM . 
 The way inwhich this frequency isadded tothereference signal isshown inthe diagram. The doppler oscillator receives ashaft rotation and H+100 +250 * IGate Reference signal r-c)----——--- Lli!*=looo##f = Fm. 16.27.—A typical 30-Mc /see coherent oscillator circuit. 
 2. R. G. 
 THERADAR EQUATION 55 /0.'-,,/ .,----- (a) (b)Figure2.27(a)Pencil-beam antenna pattern;(b) fan-beam-antenna pattern. properratiobetween theazimuth andelevation beamwidths. Manylong-range ground-based searchradarsuseafan-beam patternnarrowinazimuth andbroadinelevation. 
 Acoustic absorber material is required at the crystal edges  to reduce the reflections and, hence, the spurious responses. The upper frequency  limit depends on the accuracy that can be achieved in the fabrication of the interdigital  transducer. The SAW device must provide a response that is centered on a carrier,  as the lowest frequency of operation is about 20 MHz and is limited by the crystal. 
 QUENCY RESPONSE  VARIATION WITH TEMPERATURE  AND AGING !CCURATE RECEIVER GAIN CONTROL IS REQUIRED FOR A VARIETY OF REASONS THAT INCLUDE TARGET RADAR  CROSS 
 Con/: Pro(. .. Fo~rrtl~  h'trfl. 
 DELAY CANCELERS 3HOWN ALSO ARE THE CANCELER CONFIGURATIONS ASSUMED   WITH CORRESPONDING  : 
 19 2.3 Scattering Cross Section ofthe Target 21 2.4 The Radar Equation. 21 2.5 Beams ofSpecial Shapes 22 2.6 The Beacon Equation. 27 TRE MINIMUM DETECTABLE SIGNAL. 
 EDGE RANGE TRACKING IS DESIRED 4HIS HAS BEEN  ACCOMPLISHED IN SOME APPLICATIONS BY SIMPLY ADDING A BIAS TO MOVE THE ERROR 
 If automatic detection, sidelobe cancellation,  or MTI is needeamtfftn'a-rnrr,these must tre-separately employed in each receiving channel,  thus adding to the cost and complexity of the radar. The individual pencil beams, however,  limit the volume of space observed, which can be an advantage in rain clutter or chaff. The  MTI in the lower beams can be optimized for surface clutter and MTI in the upper bl!arns, if  used at all, can be optimized for rain and chaff. 
 15.2. The Need forSystem Testing. ‘—One general remark concerning system design issufficiently important tobemade before taking upthe design examples. 
 The amplifier uses negative feedback ofasignal taken across aresistor inthetransformer secondary, thereby correcting fordeficiencies intrans- former response. Incontrast toprevious cases, the final stage ofthe amplifier isdriven negative during the actual sweep; thus the induced voltage ontheplate ispositive and thetube does not “bog down. ”The high potential needed forquick recovery ~vhen thecurrent isrising again isprovided bythejoint action ofL1and Cl. 
 Tlie amoiliit of isolation required depends on the transmitter power and the accompany-  ing tratisr~iilter rioisc as well as tlie ruggedtless and the sensitivity of the receiver. For example,  if tllc safe value of power which might be applied to a receiver were 10 mW and if the  trarisnlitter power were 1 kW, the isolation between transmitter and receiver must be at least  50 dB.  The amount of isolation needed in a long-range CW radar is more often determined by  CWANDFREQUENCY-MODULATED RADAR71 Thepurpose ofthedoppler amplifier istoeliminate echoesfromstationary targetsandto amplify thedoppler echosignaltoalevelwhereitcanoperateanindicating device.Itmight haveafrequency-response characteristic similartothatofFig.3.2b.Thelow-frequency cutoff musthehighenoughtorejectthed-ccomponent causedbystationary targets,butyetitmust helowenough topassthesmallest doppler frequency expected. 
 8.8 Pulse Compression for Improving  the Resol ution  As has been already said in the previous section, the range of coverage is determined primarily  by the total energy, which is received from a target.  There the energy has been increased through the integration of several pulses.  The same effect can be achieved by the increase of  the pulse duration τ. 
 The availability of small, inexpensive minicomputers has  rnade it practical to obtain target tracks, not just target detections, from a surveillance radar.  Srrcli processing is tisilally called ADT (automatic detection and track). When the outputs  frorn Inore ttia~i one radar are automatically combined to provide target tracks, tlie processirig  is called ADIT (automatic detection and integrated track) or IADT (integrated ADT). 
 Wismann, W. Alpers, and W. C. 
 SHAPING INCORPORATES A STEEP BEAM SLOPE AT THE HORIZON TO ALLOW RADAR OPERATION AT LOW ELEVATION ANGLES WITHOUT DEGRADATION FROM GROUND REFLECTIONS 4HE 403 
 If the re turn is greater than the  detection threshold a target is declared.  Ais a false alarm : the noise is  greater than the threshold le vel but there is no target.  Bis a miss : a  target is present but the return is not detected.TARGET RETURNS TIMERECEIVED POWERRANDOM  NOISE DETECTION  THRESHOLD  (RELATED TO S        )minA B. 
 10. Liu, Y.; Lee, C.; Yong, H.; Jia, L.; Youshi, W.; Placidi, S.; Roedelsperger, S. FastGBSAR case studies in China: Monitoring of a dam and instable slope. 
 ABLE DOWN TO SCALES OF SEVERAL HUNDRED KILOMETERS AND MUCH SMALLER WHEN TRAVERSING A STORM FRONT  3TANDARD PRACTICE IS TO MEASURE THE INTEGRATED WATER VAPOR CONTRIBUTION IN THE VERTICAL COLUMN BELOW THE ALTIMETER BY A MICROWAVE RADIOMETER  FOR WHICH TWO OR THREE FREQUENCIES ARE REQUIRED -EASUREMENT ERRORS ARE DOMINATED BY THE ACCURACY OF ORBIT HEIGHT DETERMINATION  AND BY THE INTRINSIC PRECISION OF THE INSTRUMENT &IGURE  SHOWS A SUMMARY HISTORY OF THESE FACTORS 4HE DATA SHOW THAT  
 figuration prior to World War II, thus providing a coarse estimate of target course and speed.24 The Japanese deployed about 100 bistatic CW radar fences, called Type A, starting in 1941.26 These remained in use until the end of World War II. Type A operated between 40 and 80 MHz with 3 to 400 W of transmitter power. Maxi- mum detection ranges of up to 800 km on aircraft were achieved, with one system operating between Formosa (Taiwan) and Shanghai. 
 Merriman, R.H .. and J. W. 
 BEAM ANTENNA PATTERN AND A CONSTANT 
 Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.956x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 The problems are exacerbated when anomalous or ducted propagation occurs  (anomalous propagation,  as used herein, is when the radar energy follows the curvature  of the Earth, thus causing detection of both fixed and moving clutter at long ranges).  Figure 2.95 from Shrader53 shows PPI photographs taken with an ARSR-2 radar  mounted on a 50-ft tower in flat country near Atlantic City, New Jersey. 
 The gain of conventional pulsed crossed-field amplifiers is typically between 10 and  17 dB. By designing the cold cathode as a slow-wave circuit and introducing the RF drive at  the cathode emitting surface itself, it has been possible to achieve about 30 dB of gain in a  high-power pulse CFA with power, bandwidth, and efficiency commensurate with conven-  tional designs.43 The RF output is taken from the anode slow-wave circuit. Thk type of devrce  has been called a cathode-driven CFA6 or a high-gait] CFrl.I9  The type of crossed-field amplifier principally considered in this section can be described  as a distributed emission, or emitting sole, amplifier with a reentrant, circular format ~rt~li~ing  a forward-wave interaction without feedback. 
 Thus the output is unaffected by the level of the noise. A signal, however, causes the  output of the matched filter to increase by a factor M, equal to the ratio of the bandwidth of  the broadband filter to the bandwidth of the narrow-band (matched) filter. This form of CF AR  may not be desirable with MTI since hard limiting reduces the improvement factor or the  clutter attenuation (Sec. 
 BASED 3!2S   3PACE 
 Skolriik (ed.).  McCiraw-Hill Hook Cornpany. New York, 1970. 
 It is concluded tflat the conditions for obtaining the large forward-scatter signal are too  restrictive to be applicable in most radar situations. In general, the bistatic radar does not  possess an exploitable advantage over the monostatic radar because of any cross-section  enhancement. When conditioris permit the utilization of the enhanced forward-scatter cross  section, it is obtained at tlie expense of position location and moving-target discrimination. 
 pp.51-66.1960. 62.Waterman. A.T..Jr.:ARapidBeamSwinging Experiment inTranshorizon Propagation, IRE Trans.•V'QI.AP-6.pp.338-340. 
 TION ARE TAKEN INTO ACCOUNT. Óä°Çä  2!$!2 (!.$"//+  SECTION FOR HYBRID MULTIPATH  &ARADAY ROTATION  AND DIFFERENTIAL &ARADAY ROTATIONARE  INCORPORATED VIA PARAMETRIC MODELS DERIVED FROM MEASUREMENTS OR COMPUTATIONAL ELECTROMAGNETICS AND THE DISTRIBUTION OBTAINED BY -ONTE #ARLO SIMULATION ** 
 D. Howard, and J. W. 
 TO 
 From Fig. 8.15 it can be seen that the array will scan over the region ± 30° as the  frequency is varied from 0.968/0 to 1.035/0, where /0 is the frequency corresponding to the  hroadside position of the beam. As the frequency is increased, the factor m = 10 applies and  the same angular region is scanned as the frequency varies from 1.075/0 to 1.149/0• Form= 11,  1he corresponding frequency range is from J.183/0 to 1.264/0• The ability to radiate from the  ... 
 The most important ice types from a radar point of view are first-year  (FY 1 to 2 m thick), multiyear (MY > 2 m thick), and a conglomeration of thinner  types (< 1 m thick). Like snow, sea ice influenced by solar melting and above freezing temperatures  scatters microwaves very differently from the more normal cold-surface ice. In win - ter, the cold MY ice scatters much more than cold FY ice. 
 No other sensor can measure range to the accuracy possible with radar, at such long ranges, and under adverse weather conditions. Surface-based radars can be made to determine the range of an aircraft to an accuracy of a few tens of meters at distances limited only by the line of sight, generally 200 to 250 nmi. Radar has demonstrated its ability to measure interplanetary distances to an accuracy limited only by the accuracy to which the velocity of propagation is known. 
 SION AT 2&  AVOIDING SOME OF THE LIMITATIONS OF ANALOG DEVICES )SSUES SUCH AS RECIP 
 401-404, available from IEEE, New York, 77CH1271-6.  AES.  135. 
 CONGESTED (& BAND  AS WELL AS JAMMING SOURCES *AMMING SOURCES MAY BE LOCATED ON THE TARGET PLATFORM ITSELF SELF 
 In the reference image, OF vectors are used to move the detected change areas in the ﬂow direction. The destination of an area is then compared with the same location in the mission image. If there is a matching area based on location and size, then the two change areas are excluded from the change maps. 
 Beams of this type are of particular interest because they are easily generated. They  may be used for transmission in a system where the receiving antenna has a cluster of  simultaneous beams, or, as previously discussed, they may be used in a search system  to reduce the number of angular cells in regions of shorter range. Monitoring . 
 If the  receiver output exceeds the threshold, a signal is assumed to be present. This is called threshold  detection. Consider the output of a typical radar receiver as a function of time (Fig. 
 During the latter part of World War II, airborne early-warning (AEW)  radars were developed by the U.S. Navy to detect low-flying aircraft approaching a  task force below the radar coverage of the ship’s antenna. The advantage of the air - borne platform in extending the maximum detection range for air and surface targets is  apparent when one considers that the radar horizon is 12 nmi for a 100-ft antenna mast  compared with approximately 195 nmi for a 25,000-ft aircraft altitude. 
 42. Brennan, L. E., and F. 
 Thk arrangement isusually spoken ofasa‘‘differentiating circuit. ”The steepness ofthe front edge ofthe pulse islargely deter- mined bythat ofthewavefront. Inorder toobtain asteep rear edge, RC should besmall, but apoint isreached foragivenwavefront atwhich decreasing this product reduces the amplitude. 
 4(% 
 intervals sothat itcan rotate. Asthe inner conductor turns, thewavelength intheline varies, causing thebeam toscan 6.5°. Larger scans bythis method arequite feasible. 
 SPACE PROPAGA 
 Their deviation rrom the symmetrical shape  of a sphere will result in the rellected signal containing some energy in that polarization  component accepted by the antenna. This limits the ability of circular polarization to reject  precipitation clutter.  The rejection or rain echoes by a circularly polarized radar depends on the purity with  which circular polarization can be generated by a practical antenna, as well as the deviation  of the precipitation particles from a spherical shape.117 The cancellation or the orthogonal  polarization by an exceptionally well-designed, well-maintained antenna might be limited to  about 40 dB.79 To achieve 40 dB of cancellation the voltage ellipticity ratio of the antenna  (ratio of the minor axis to the major axis of the polarization ellipse) must be 0.99, a difficult  value to achieve. 
 19. The most accurate timing device atpresent available isaprecision oscillator. This device can beused for the generation ofamovable marker only bysome method involving acontinuous shifting ofitsphase. 
   =   \             &OR MOST SINGLE RADAR 
 He  uses as first the denomination “Intermediate Frequency” , and alludes  the  possibility of double heterodyning.   1921 The invention of the Magnetron as an efficient transmitting tube by the US - American physicist Albert Wallace Hull   1922  The American electrical engineers Albert H. Taylor  and Leo C. 
 0OL.#!2S POLARIMETRIC DOPPLER RESEARCH  RADAR v IN  0ROC  )NT  'EOSCI  2EMOTE  3ENS  3YMP  ;)'!233  =   )%%%  (ONOLULU      PP n  ( ,IU AND 6 #HANDRASEKAR  h#LASSIFICATION OF HYDROMETEORS BASED ON POLARIMETRIC RADAR MEA 
 496–505, March 1999. 129. G. 
 TO 
 Space-time adaptive ar- ray processing combines a two-dimensional array of signals sampled at different instances of time and at different spatial locations. A basic block diagram of a radar incorporating space-time adaptive array pro- cessing is shown in Fig. 16.23. 
 Proceedings of 2013 Asia-Paciﬁc Conference on Synthetic Aperture Radar (APSAR), Tsukuba, Japan, 23–27 September 2013. 18. Luo, Y.; Song, H.; Wang, R.; Deng, Y.; Zhao, F.; Xu, Z. 
 Srrppl. to  IkIIl: 'l'rtrtr\  or^ .It~rr~.sj~trc.c~ crr~rl I<lcc~rronic S~.stt~rtrs, vol. AES-3, no. 
 Sensors 2019 ,19, 2921 T able 2. Experiment parameters. r(m) θbw(rad) θ(rad) λ(mm) Br(MHz) Rmax (m) Rmin (m) 1 π/32 π 17.50 150 400 200 Rmaxrepresents the maximum slant range from the imaging scenes to the ArcSAR system and Rminrepresents the minimum slant range from the imaging scenes to the ArcSAR system. 
 POWER POINTS   THEN THE RELATION BETWEEN THE ACTUAL RADAR CLUTTER CROSS SECTION  R   C  AS INFERRED FROM THE RECEIVED POWER VIA THE  RADAR  EQUATION  AND THE .2#3 R    IS GIVEN BY   R     R C  !F   . £x°n  2!$!2 (!.$"//+  WHERE FOR A RADAR WITH AN ANTENNA BEAMWIDTH  " AND RECTANGULAR PULSE OF LENGTH  S   VIEWING THE SURFACE AT RANGE 2 AND GRAZING ANGLE X  THE AREA !F IS EITHER   !F   O  "2  SINX    FOR BEAM 
 The triangular-shaped pulse is little better, since its {3a product is ~n.  The radar" uncertainty" relation seems to have the opposite interpretation of the uncer­ tainty principle of quantum mechanics. The latter states that the position and the velocity of  an electron or other atomic particles cannot be simultaneously determined to any degree of  accuracy desired. 
 YEAR &9  TO  M THICK   MULTIYEAR -9    M THICK   AND A CONGLOMERATION OF THINNER TYPES    M THICK  ,IKE SNOW  SEA ICE INFLUENCED BY SOLAR MELTING AND ABOVE FREEZING TEMPERATURES  SCATTERS MICROWAVES VERY DIFFERENTLY FROM THE MORE NORMAL COLD 
 17. Rhodes, U. R.: "Introduction to Monopulse," McGraw-Hill Book Company, New York, 1959. 
 Measurements of range have to be within 30 meters accuracy (or within  1% of the maximum range scale in use) and within 1° bearing (azimuth angle).  Navigational buoys with the characteristics given in Table 22.1 have to be detectable  at a minimum range of 40 meters. Two “point” targets on the same bearing have to  appear as two distinct targets if they are separated by more than 40 meters in range. 
 Scatter from snow comes from many cen - ters within the illuminated volume, so the conditions for Rayleigh fading are met. FIGURE   16. 38 Frequency response of the look-direction modulation  ratio for a soybean field with horizontal polarization at incidence angles  of 0, 30, and 60° ( after F . 
 D. K .. and Shrader, W. 
 To accommodate the aspect dependent scattering, there are mainly two approaches, the subaperture approach and full aperture approach [ 2]. The subaperture approach [ 1] divides the whole aperture into the subapertures and assumes that the scatterings are constant in the subaperture. Then, the narrow angle imaging methods such as matched ﬁltering [ 3] and an L1regularization based SAR imaging method [ 4,5] can be adopted for the subaperture imaging. 
 Equipments that provide plan and height information continuously onalltargets inthe field of view, using asingle antenna system, are obviously preferable. The limitations discussed inChap. 4ontherange out towhich asubstantial area can berapidly scanned preclude thedesign ofasingle radar system which will gi~,e both plan and height information with the necessary accuracy, asoften asisdesirable, and out toarange limited only bythe Ground range Inmiles FIG, 6,24.—Calibration ofbeigbt readings of.4N/TPS-10.optical horizon. 
 TION OF THE TARGET ECHO )T THEN CALCULATES THE RANGE SUM AS  24   22    C$4RT   , 4HIS  METHOD CAN BE USED WITH ANY SUITABLE MODULATED TRANSMISSION AND ANY TYPE OF TRANS 
 wliicli tlie gates must be repositioned by a feedback-control systetn. When the error signal is  zcro. tlie range gates are centered on the pulse. 
 ,-/ - 4HE CLUTTER SUPPRESSION NEEDED FROM AN -4) OR -4$ RADAR DEPENDS ON THE CHARACTER 
 MARILY DUE TO A TURBULENCE AND WIND SHEAR CHANGE IN WIND VELOCITY WITH ALTITUDE  -EASUREMENTS SHOW A TYPICAL AVERAGE VALUE OF  R  VT    MS FOR TURBULENCE AND  R VS    MSKM  FOR WIND SHEAR ! CONVENIENT EQUATION IS  S QVS EL   2 MS   FOR THE EFFECT OF WIND SHEAR  PROVIDED THE RAIN FILLS THE VERTICAL BEAM (ERE  2 IS THE  RANGE TO THE WEATHER  IN NAUTICAL MILES  AND  QEL IS THE ONE 
 J. Richards (ed.). Van  Nostrarid Reinllold Co., New York, 1969. 
 There are basically two types of CRT—the ‘soft’ or  gas-filled and the ‘hard’ or highly evacuated. Radar  uses the hard tube. ee  -~ 59  . 
 They usually combine data coherently from each receiver site to form a large receive aperture. Multiple transmitters can be used with any of these configurations. They can be located at separate sites or colocated with the receive sites. 
 Beamwidth is 2°; antenna height, 5OX; total squint angle, 2.25°; and reflection coefficient, 1.0. 1. The shape and amplitude of the envelope of maximum errors (dash curves) are dependent only on the antenna-beam pattern function in the elevation plane and the ground-reflection coefficient and are independent of the antenna electri- cal height above the ground. 
 1For asegment ofspherical surface ofradius Rwefind independently ofthesize ofthesegment and ofthewavelength h. This formula isvalid aslong asthediameter dofthesegment (perpendicular totheincident beam) islarger than v’2kR, and provided that theedge of the segment deviates sufficiently (>k/4) from aplane perpendicular to the incident beam, since otherwise edge effects may become important. Ifthesurface isnotspherical theformula isstill valid ifwetake forRthe geometric mean ofthe two principal radii ofcurvature. 
 The amount of attenuation caused by each ofthe various factors depends to a substantial degree on the radar wavelength.It causes a decrease in echo strength. Attenuation is greater at the higherfrequencies or shorter wavelengths. Attenuation by rain, fog, clouds, hail, snow, and dust The amount of attenuation caused by these weather factors is dependent upon the amount of water, liquid or frozen, present in a unit volume of airand upon the temperature. 
 RESOLUTION SONDES THAT MAY BE LOWERED TO THE SURFACE FROM A SHIP  THE IMPRESSION IS GIVEN THAT THE EVAPORATION DUCT MAY BE MEASURED DIRECTLY &OR PRACTICAL APPLICATIONS  HOWEVER  THIS IMPRESSION IS FALSE AND A DIRECT MEASUREMENT SHOULD NOT BE ATTEMPTED $UE TO THE TURBULENT NATURE OF THE TROPO 
 CAVITY CIRCUIT  BUT    IT IS NOT CAPABLE OF AS HIGH A POWER AS THE COUPLED CAVITY 4HUS  THE BANDWIDTH OF A 474 DECREASES AS ITS POWER INCREASES /N THE OTHER HAND  AS MEN TIONED PREVIOUSLY   THE BANDWIDTH OF A KLYSTRON INCREASES WITH INCREASING POWER  SO THAT THE BANDWIDTHS OF THE 474 AND THE KLYSTRON ARE GENERALLY COMPARABLE FOR MANY HIGH 
 Postdetection integration is therefore  preferred, even though the integrated signal-to-noise ratio may not be as great. As mentioned  in Sec. 10.6, an alert, trained operator viewing a properly designed cathode-ray tube display 1s  a close approximation to the theoretical postdetection integrator. 
 Initially the SVD approach used to extract the maximally correlated information inherently present in the image is introduced. The useful information of chirp in range and in azimuth are shown as extracted from the raw data. The SVD decomposition is discussed to explain the correlation exploitation mechanism. 
 BISTATIC RADAR  23.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23  80. M. Matsuo et al., “Bistatic radar cross section measurements by pendulum method,” IEEE  Trans ., vol. 
 SITES AT HIGH RESOLUTION AND SHORT AVERAGING TIMES  TO BE DISCUSSED LATER !S IT TURNS OUT  MICROWAVE SEA CLUTTER SPECTRA HAVE A RATHER SIMPLE FORM AT THE LOWER  GRAZING ANGLES &IGURE  ILLUSTRATES TYPICAL SPECTRAL BEHAVIOR AT THE TWO POLARIZA 
 Maksimiuk, and G. Reitsma, “FM radio based bistatic radar,” IEE Proc.- Radar Sonar Navig ., vol. 152, no. 
 2.6a,which represents asingle oscilloscope trace starting atthe time ofthe transmitted pulse oratsome known time thereafter. This isatypical single trace showing noise only, without signal. 1Clearly only arather strong signal could stand outconspicuously among these fluctuations. 
 6ALUE 0ROBLEMS  'ENERAL FORMULATIONS  OF THE '"60  THOUGH ELEGANT  ARE OF LITTLE PRACTICAL VALUE  AND SOME KIND OF APPROXI 
 IES WIDELY 4HUS  ALTHOUGH WE CAN DEVELOP  AVERAGE MODELS LIKE THOSE DESCRIBED IN  3ECTION   DETAILS ARE MUCH MORE COMPLEX 4HE  R  VARIES WITH SEASON  MOISTURE  CONTENT  STATE OF GROWTH  AND TIME OF DAY &IGURE  SHOWS THE SEASONAL VARIATION FOR CORN COMPARED WITH A MODEL  PRESENTED IN THE REFERENCE 4HE MUCH LARGER VARIATION AT  R  APPARENTLY RESULTS FROM  THE LARGER EFFECT AT VERTICAL OF THE SOIL AND CONSEQUENTLY ITS MOISTURE CONTENT 4HE RAPID  D" SWING BETWEEN -AY  AND *UNE  RESULTS FROM DRYING OF THE SOIL %VEN AT   WHERE ATTENUATION THROUGH THE CANOPY MASKS THE SOIL EFFECT  THE SEASONAL VARIATION EXCEEDS  D" $IURNAL VARIATIONS ARE RELATIVELY SMALL BUT FINITE 4HEY RESULT BOTH FROM PLANT MOISTURE CHANGES AND FROM MORPHOLOGICAL CHANGES A CORN PLANT ACTUALLY LIFTS ITS LEAVES hTO MEET THE SUNv MORNING GLORIES CLOSE THEIR FLOWERS AT NIGHT  -OST CROPS ARE PLANTED IN ROWS 4HIS CAUSES AN AZIMUTHAL VARIATION OF  R    AS SHOWN  IN &IGURE  4HE MODULATION SHOWN IS THE RATIO OF  R  LOOKING PARALLEL TO THE ROWS  MORE VEGETATION  TO THAT LOOKING NORMAL 4HIS PHENOMENON IS MUCH MORE PRONOUNCED AT THE LOWER FREQUENCIES 3OME GENERAL PROPERTIES OF VEGETATION SCATTER ARE VISIBLE IN &IGURE   !T LOW  FREQUENCIES  THE DECAY WITH  P  IS RAPID OUT TO ABOUT  AND THEN MORE GRADUAL MOST  OF THE STEEP PART RESULTS FROM SURFACE ECHO !T HIGHER FREQUENCIES  THE PLANT ATTENU 
 In the two-hop ranges, the no-gradient assump - tion causes more distortion. In general, errors of this nature have little impact on  performance prediction. However, near-real-time analysis for virtual range and  azimuth correction to great-circle distance and bearing (grid registration) requires  that tilt or gradient effects be taken into account. 
 PANEL 
 This model was originally proposed as a PSI technique, and has been successfully applied in a large amount of cases. However, under the assumption of a pure linear varying characteristic among all temporal periods, the linear velocity model has signiﬁcant limitations. When the real deformation of the monitored object is close to a linearly varying characteristic, the residual phase can be easily suppressed within the range ofa whole phase cycle; however, when a strong non-linear component exists in the total displacement, theresidual phase may possibly exceed the reasonable range of [−π,π],thus inducing a non-unique solution of unknown parameters and large inaccuracy. 
 ● Some of the radiated energy is intercepted by a reflecting object, usually called  a target , located at a distance from the radar. ● The energy intercepted by the target is reradiated in many directions. ● Some of the reradiated (echo) energy is returned to and received by the radar antenna. 
 TO 
 4. Three of the five filters will reject fixed clutter and respond to moving tar- gets. Two filters will respond to targets at zero doppler and its ambiguities. 
 About 11  percent of the power is reflected when the VSWR is 2.0, corresponding to less than 10 dB of  isolation. Thus, a receiver protector is almost always required. It also reduces to a safe level  radiations from nearby transmitters. 
 568-571, January 1963. 62. Detlefsen, J.: Application of Multistatic Radar Principles to Short Range Imaging, Proc. 
 Every reader can be  sure that he will find in these books what is true, what  is useful, and what is provocative of thought.  “Knowledge is power,” wrote Bacon; moreover, it  is the only power that does not carry in itself the seeds  of its own corruption; thefe is no substitute.” Know-  ledge, indeed, is the only power worth pursuing in this —  modern world. And in the pursuit we shall gain under-  standing and stay humble if we remember our heritage,  the work of all those who have gone before to guide us. 
 The “trigatron” (Fig. 10.40) differs from the series gap inhaving but one spark gap, across which thefullline voltage isapplied. Conduc- tion isinitiated byapplying asteep high-voltage wave toatrigger elec- trode; this presumably draws corona current sufficient toinitiate the main discharge. 
 23-25, 1973, IEE Conference Publication No. 105.  62. 
 van de Lindt, W. J.: Digital Techniques for Generating Synthetic Aperture Radar Images, I B,\1 Jo11r.  of Research and Development, vol. 
 66Onecriterion fortheselection ofagood"random" phase-coded waveform isthatitsautocorrelation func­ tionshouldhaveequaltime-sidelobes. (RecallfromSec.10.2thattheoutputofthematched filleristheautocorrelation oftheinputsignalforwhichitismatched, ifnoisdcan beneg­ lected.)Thebinaryphase-coded sequence of0,1tvaluesthatresultinequalsidelobes after passagethrough thematched filteriscalledaBarkercode.Anexample isshowninFig.11.19a. ThisisaBarkercodeoflength13.The(+-)indicates 0phaseand(-)indicates 1tradiansphase. 
 Also, a significant portion of the energy radiated by the feed would not intercept the  paraboloid and would be lost. The lost "spillover" energy results in a lowering of the overall  efficiency arid defeats the purpose of the uniform illumination (maximum aperture efficiency).  011 the other hand, if the angle subtended by the paraboloid at the focus is large, more of  tlie radiation from the feed will be intercepted by the reflector. 
  TO  
 Sens. 2007 ,45, 3552–3560. [ CrossRef ] 31. 
 2#3 #ONVERSELY  THE SAM 
 As themachine speed increases, thecentrifugal weights compress thespring and reduce the pressure onthe pile, increasing itsresistance. Should themachine exceed itsrated speed, thecarbon pile will becompressed by the spring under the adjusting screw. Atrated speed, the carbon pile isbalanced between these two springs and aslight change inspeed will cause arelatively large change inresistance. 
  #OMMUNICATIONS  CAN OPERATE WITHIN THE  5(& 
 100, no. C2, pp. 2591–2611, February 1995. 
 This radome depends upon asandwich wall construction ofFiberglas laminated skins and Hycar core togive itthedesirable elec- trical and structural characteristics. FIG,9.40,—The largest airborne radome. Ithouses an8-ftantenna under aTBM aircraft.. 
 R.: Statistical Aspects of Ideal Radar Targets, Proc. IEEE, vol. 55, pp. 
 Atlas: Simultaneous Ocean Cross-Section and Rainfall Measure- ments from Space with a Nadir-Looking Radar, J. Atmos. Ocean. 
 PHASED ARRAY RADAR ANTENNAS  13.576x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 The benefits of DBF include improved dynamic range, faster search frame times if  multiple simultaneous beams are used, and better control of amplitude and phase for  adaptive nulling and lower sidelobe levels. Shipboard radars had been designed to operate primarily in open ocean environ - ments. However, the changing world will require shipboard radars to operate much  closer to land. 
 21.19  Motion Compensat ion  ........................................  21.20  Squint Mode  ......................................................  21.20  Spotlight M ode  .................................................. 
 51. Liu, Y.L.; Huang, H.J.; Liu, Y.X.; Bi, H.B. Linking land subsidence over the yellow river delta, China, to hydrocarbon exploitation using multi-temporal insar. 
  PHASED ARRAY A NTENNA v -ICROWAVE *  VOL    PP n  -AY   2 , "RITTON  4 7 +IMBRELL  # % #ALDWELL  AND ' # 2OSE  h!.309 
 52. Steinberg, B. D.: Target Clutter, and Noise Spectra, pt VI, chap. 
 NIQUE THUS  #/32/ AND ,/2/ ARE BECOMING OBSOLETE -ONOPULSE TRACKING IS INHERENTLY INSENSITIVE TO ANGLE DECEPTIVE JAMMING FROM A  SINGLE POINT SOURCE 4HIS IS A RESULT OF THE MONOPULSE ANGLE 
 Haase, and E. C. Wetzlar, “False alarm control in automated  radar surveillance systems,” in IEE Int. 
 2008 ,43.[CrossRef ] 210. Sensors 2019 ,19, 516 24. Wang, C.; Chen, L.; Liu, L. 
    PP n  *UNE   2 * "ARKER ET AL   -ODERN -ICROWAVE AND -ILLIMETER 
 One is that because different frequencies are required in order to steer the beam, amplitude fluctuations in the target return are induced. These tend to di- lute the quality of target angle information available in the multiple-beam target returns. The effect can be compensated by averaging out the target fluctuation effects by the use of noncoherent integration of multiple-frequency diversity subpulses in each beam. 
 Because the aircraft need not fly orthogonal tracks, the time required for measurements of cloud systems is dramatically reduced. Moreover, severe storms (which could otherwise not be penetrated along an orthogonal track) can be observed fully by an aircraft outside the regions of severe weather. Among the more significant challenges facing researchers today is the need to make global measurements of precipitation. 
 This occurs because each layer (semiconductor, ceramic sub - strate, metal base, etc.) exhibits both a thermal resistance and a thermal capacitance.  Then, there exists an equivalent thermal time constant ( t) for each packaging material  layer. This thermal time constant has been approximateded9 as  t  =  0.4053 * (F2rC/KTH)  (11.2) where F is thickness (cm), r is density (gm/cc), C is specific heat (Wsec/gm °C), and  KTH is thermal conductivity ( W/cm°C). 
 Figure 10a1–d1 are the imaging results with 32 pulses, and Figure 10a2–d2 are results with 64 pulses. From the upper-left to the lower-right, FFT-based, Relax-based, APES-based and the proposed KA-DBS algorithm are given. It can be seen that the imaging results become better and better from the upper-left part of Figure 10to the lower-right part of Figure 10. 
 Pan, “A scattering model for perfectly conducting random surfaces:   I. model development,” Int. J. 
 The traces for HH  (dots) and HV (short dashes) are each shifted down by 5 dB for clarity, whereas those  for the VV (long dashes) and VH (solid) are “as is” (not shifted). The plate was rotated  about a vertical axis parallel to one edge of the plate, and the incident or received  polarization was either parallel to (V) or perpendicular to (H) that axis, respectively . FIGURE 14.6  Measured RCS pattern of a 39 l, 15° half-angle metal ogive ( after L. 
 The principle utilized by phase interferometry is that the phase differ- ence between offset antennas is proportional to the sine of the angle of arrival of a received target echo as sketched in Fig. 20.1/z. Radars such as the VEB, the V-beam, the vertical line array plus 2D, the crossed-line array, and the phase interferometer plus 2D, which obtain simulta- neous tricoordinate (range, azimuth, and elevation or height) measurements on a target but do not have significant resolution in the elevation dimension compared with their elevation coverage, might appropriately be termed 2ViD radars. 
 They can be caused by the feedthrough of the RF  drive-pulse when it is wider than the d-c modulator pulse, or they can be due to spurious  oscillations, called band-edge oscillations, that occur just outside the normal tube­ bandwidth.16· 17  The insertion loss of a CF A is low and might be less than 0.5 dB. The RF drive will thus  appear at the output of the tube with little attenuation. In a low-gain amplifier the input power  which appears at the output can be a sizable fraction of the total. 
   PP n  .OVEMBER   ! ! !USHERMAN  ! +OZMA  * , 7ALKER  ( - *ONES  AND % # 0OGGIO  h$EVELOPMENT IN RADAR  IMAGING v )%%% 4RANS  VOL !%3 
 TERISTICS AFTER 9 3 +IM ET AL  &)'52%     0OLARIMETRIC ELLIPSE  B IS  THE ELLIPTICITY ANGLE  AND  X  IS THE ORIENTATION  ANGLE 4HE ELLIPSE IS THE LOCUS OF THE END OF THE % VECTOR THROUGHOUT A CYCLE  . 
 Howard. D. D.: Predicting Target-Caused Errors in Radar Measurements, Electronic Warfare Defense  Elecrroriio, vol. 
 Weapon control radar . This name is usually applied to a single-target tracker used  for defending against air attack. Guidance radar . 
 Figure 2shows the simulated current ﬁelds of vortex. The parameters of the simulation are given in Table 1. Comparing Figure 2a,b, the value of αclearly affects the velocity magnitude of the vortex current ﬁeld; the velocity magnitude increases with increasing αvalues. 
 The radar transmitter must not only be able to generate the  peak and average powers required to detect the desired targets at the maximum range,  but also has to generate a signal with the proper waveform and the stability needed for  the particular application. Transmitters may be oscillators or amplifiers, but the latter  usually offer more advantages. There have been many types of radar power sources used in radar (Chapter 10). 
 FIQ.6.32.—Units ofAN/APS4. Covers, radome, andfairing ofmain unitareremoved. Inuse,main unitissuspended from bracket shown atbottom inthisview. 
 MERCIAL AIRLINE FLIGHTS  AND VI  REGISTERING AIRPORTS  WHERE TRACKS ORIGINATE OR TERMINATE  4HE KEY TO ROBUST #2 IS THE FUSION OF ALL AVAILABLE INFORMATION IN A CONSISTENT PROBABILIS 
 Frequency multiplication of these VHF sources is often used to generate the  radar RF frequencies required; however, this multiplication process results in increase  in phase noise performance by 20 log10(M) dB where M is the multiplication factor. A  variety of other source technologies, such as Surface Acoustic Wave (SAW) oscilla - tors, have been exploited to achieve improved phase noise performance. SAW oscil - lators enable lower far-from-carrier phase noise, largely due to their higher frequency  operation and the resulting lower frequency multiplication factor required to generate  the equivalent radar RF output frequencies. 
 Also shown in Fig. 15.18 is a horizontal line labeled • "average SCR improve- ment." This indicates the level corresponding to the average of the optimum SCR curve across one doppler interval and may be considered as a figure of merit for a multiple-filter doppler processor somewhat analogous to the MTI improvement factor defined for a single doppler filter. In Fig. 
 ITY OF ELECTRONIC COUNTERMEASURES IN THE BAND 4HE + A BAND  ALTHOUGH ATMOSPHERIC 
 the signal-to-noise ratiowillbe within 0.5dBofoptimum forInranging overavalueof0.44 11fora nonnuctuating targetoraSwerling caseI,and0.34nforaSwerling case2.59 Thequantization ofsignalsintobuttwolevels(zeroorone)inthebinarymoving-window dctector resultsinalossofabout1.5to2dBinsignal-to-noise ratioascompared totheideal post-detection integrator.5355.57Whentheamplitude isquantized intomorethantwolevels, thelossisless.Forexample, quantization intofourlevels(2bits),reduces thelosstoabout onc-third thatexperienced intwo-level, orbinary,quantization (Ibit).60 ;\corollary advantage ofthebinarymoving-window detector isthatitislesssensitive to theeffectsofasinglelargeinterference pulsethatmightexistalongwiththetargetechopulses. fntheusualintegrator, thefullenergyoftheinterference pulseisadded.Inthebinary moving-window detector. however, itcontributes nomorethanwouldanyotherpulsethat crossesthefirstthreshold sincea Iisrecorded nomatterwhattheamplitude. 
 Thechiefdiffer­ encebetween theelectronic andtheoperator thresholds isthattheformermaybedetermined withsomelogicandcanbeexpected toremainconstant withtime,whilethelatter'sthreshold mightbedifficult topredictandmaynotremainfixed.Theindividual's performance aspartof theradardetection processdepends uponthestateoftheoperator's fatigueandmotivation, as wellastraining, Thecapability ofthehumanoperator aspartoftheradardetection process canbe determined onlybyexperiment. Needless tosay,inexperiments ofthisnaturetherearelikely tobewidevariations between different experimenters. Therefore, forthepurposes ofthe presentdiscussion, theoperator willbeconsidered thesameasanelectronic threshold detec­ tor,anassumption thatisgenerally validforanalert,trainedoperator. 
 BOLIC EQUATION v  )%%% 4RANSACTIONS ON !NTENNAS AND 0ROPAGATION   VOL   PP n   /CTOBER   & * 2YAN  h!NALYSIS OF ELECTROMAGNETIC PROPAGATION OVER VARIABLE TERRAIN USING THE PARABOLIC  WAVE EQUATION v .AVAL /CEAN 3YSTEMS #ENTER 42 
 RADAR HTTPLUNARGSFCNASAGOVMISSIONSSCANDINSTHTML o  0ERIAPSIS AND  APOAPSIS ARE  RESPECTIVELY  THE POINTS ALONG AN ELLIPTICAL ORBIT THAT ARE CLOSEST TO AND FARTHEST FROM THE  GRAVITATIONAL CENTER OF THE SYSTEM.   30!#% 
 FREQUENCY RAMP AND THE FREQUENCY OF THE RAMP BEING TRANSMITTED 4HE PERFORMANCE OF &- 
 M. Soumekh, “SAR-ECCM using phased-perturbed LFM chirp signals and DRFM repeat  jammer penalizer,” IEEE Trans ., vol. AES–42, no. 
 21and Nov. 16,1944, astudy was made bytheOperations Analysis Section ofNinth AirForce ofthereporting work done bythethree FDP’s ofIXTAC. Because of thedifference intheamount and character ofairactivity byday and by night, daily and nightly averages were separately computed for the follo\ving data: theaverage number ofseparate plots pertrack reported, theaverage track duration inminutes, and theaverage number ofplots perheight reported. 
 To measure the individual frequencies, they must be separated from one another. This  might be accomplished with a bank of narrowband filters, or alternatively, a single frequency  corresponding to a single target may be singled out and continuously observed with a narrow­ band tunable filter. But if the motion of the targets were to produce a dopplcr frc<.Jucncy shift,  or if the frequency-modulation waveform were nonlinear, or if the mixa were not operated in  its linear region, the problem of resolving targets and measuring the range of each bccomt:s  more complicated. 
 TIME 
 Target Angle and Range Scintillation (Glint) Reduction.  Target-caused errors  in angle and range tracking may be reduced by filtering, such as reducing tracking  servo bandwidth. However, sufficient servo bandwidth must be retained to follow  target trajectories. 
 8.19. A signal of frequency /0, whose phase is to be shifted an amount <J,, is mixed with a  signal from a variable frequency oscillator fr in the first mixer. The output of the variable­ frequency oscillator .fc is also passed through a delay line with a time delay r. 
 For acylinder ofradius Rand length 1,both large compared toX,we obtain R12 u=27r —A(9) forincidence perpendicular tothe axis. For the same cylinder, ifthe beam forms anangle Owith the normal tothe axis the average cross section (averaged over several lobes) isapproximated by (lo) valid forsmall angles oexcluding themain lobe. For rur~ed surfaces, theformulas ofgeometrical optics can ordinarily beused. 
 NOISE RATIO VERSUS RANGE FOR SURFACE 
 Skolnik (ed.~  McGraw-Hin Book Co., New York, 1970.  37. Swerling, P.: Probability of Detection for Fluctuating Targets, IRE Trans., vol. 
 Cook, “ECM/ECCM systems simulation program, electronic and aerospace systems  record,” IEEE Conv. Rec. EASCON ’68 , September 9–11, 1968, pp. 
 53. Pringle. [I. 
 OBJECT 4RACKING 2ADAR  -/42   PROVIDE ELECTRONIC BEAM MOVEMENT OVER A LIMITED SECTOR OF ABOUT  o  O TO  APPROXIMATELY  o O PLUS MECHANICAL MOVEMENT OF THE ANTENNA TO MOVE THE COVERAGE  SECTORn 4HE OUTPUT WILL BE MECHANICAL SHAFT POSITIONS LOCATING THE NORMAL TO THE  ARRAY PLUS DIGITAL ANGLE INFORMATION FROM THE ELECTRONIC BEAM SCAN FOR EACH TARGET °nÊ /, 
 CAVITY KLYSTRON OSCILLATOR CALLED THE  REFLEX KLYSTRON THAT WAS OF LOW POWER AND MAINLY USED AS A RECEIVER LOCAL  OSCILLATOR  BUT IT HAS GENERALLY BEEN REPLACED BY SOLID 
 Each TR module is connected to separate distribution networks feeding  H- and V-polarized elements, which support polarization diversity as well as eleva - tion beam steering. There are two parallel receive channels (dedicated to the H- and  V-polarized antenna elements). RISAT has five modes, each of which may operate at  a variety of incident angles. 
 613. 33. Best, A. 
 -",Ê / 
 WAY DOPPLER SHIFT IS GIVEN BY  F D   62K COSX    WHERE K IS THE RADAR WAVELENGTH   62 IS THE RADAR PLATFORM SPEED  AND  X IS THE ANGLE  BETWEEN THE VELOCITY VECTOR AND THE LINE OF SIGHT TO THE TARGET .OTE THAT THE RELATIVE RADIAL VELOCITY RANGE RATE  TO THE STATIONARY TARGET IS  6 RELATIVE    
 Several nodding-antenna height finders, notably the British Type 13 and the widely deployed United States AN/TPS-10, appeared in the mid- to late 1940s, when higher-frequency technology began to emerge.6 The AN/TPS-10 X-band nodding-antenna height finder radar series was subsequently replaced by the AN/ FPS-6, an S-band nodding-antenna radar also designed for the U.S. Army.7 The AN/MPS-14 was a mobile version of the radar, and the AN/FPS-89 was an im- proved fixed-site version. The elevation beamwidth of the AN/FPS-6 was 0.9°, its azimuth beamwidth was 3.2°, and the entire antenna nodded at a rate of 20 to 30 nods per minute. 
 In Proceedings of the SPIE—International Conference on Image and Signal Processing for Remote Sensing, Berlin, Germany, 10–13 September 2018. 20. Golub, G.H.; Reinsch, C. 
                                      . £È°x{  2!$!2 (!.$"//+  &)'52%     -EDIAN VALUES OF  R & AT LOW DEPRESSION ANGLES BASED ON   4ABLE  OF "ILLINGSLEY    /&.2&,$4&%*", %           
   3%! #,544%2  £x°£ !T (& AND -ILLIMETER 
 Geophys. 2013 ,56, 1476–1486. 24. 
 Hansen. R. C. 
   SUPPLEMENT v  '%#  %LECTRONICS   ,TD   3TANMORE   %NGLAND   -EMORANDUM  3,- 3UPPLEMENT   *ULY    2 7 ,ARSEN AND 2 # (EIMILLER  h"ISTATIC CLUTTER DATA M EASUREMENT PROGRAM v %NVIRONMENTAL  2ESEARCH )NSTITUTE OF -ICHIGAN  2!$# 
  # 
 TO 
 24.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 will be expected to operate. The so-called environmental diagram depicts spectral,  spatial, and amplitude characteristics of the radar environment (clutter, ECM such as  chaff, intentional interferences, and—perhaps—interferences from neighboring EM  apparatuses) and is used to assist the radar waveform design. An example of an envi - ronmental diagram is on p. 
 UNIT  AT THE BOTTOM OF THE DUCT ILLUSTRATED BY THE DASHED LINE  'REAT SEMIPERMANENT SURFACE HIGH 
 SPECTIVE  INTEREST IS USUALLY CENTERED  NOT ON THE IONOSPHERE PE R SE BUT ON HOW IT DETER 
 Thus clock stability is A<|>/ 2TT/T. Again, atomic clocks are usually required, with crystal oscillators used for short-term stability. However, when T < ~ 1 s, integral crystal oscillators are usually acceptable. 
 cc 
 Bedinger, “Transmit/receive module  technology for X-band active array radar,” Proceedings of the IEEE , vol. 79, no. 3, pp. 
 Itisa quarter wavelength thickanddesigned sothatenergyretlected fromthefrontsurfacecancels theenergywhichentersthematerial andisreOected fromtheinnersurface. Adestructive interference absorber isanalogous totheantireOection coatings appliedtoopticallenses.Itis inherently narrowband. Another typeofabsorber isonewhichinternally dissipates theenergyincident uponit.It isusuallymuchthickerthanthedestructive interference absorber buthastheadvantage of beingbroadband. 
 (a) NRCS contrast of eddy spirals Δσand ( b) NRCS contrast of SAR image Δσrunder different wind directions and radar frequencies. Fifty simulations are averaged to reduce speckle bias. Figure 15a,b shows that under different wind directions, the values of ΔσandΔσrare slightly different. 
 MANCE STARTS TO FALL SIGNIFICANTLY BELOW THE OPTIMUM&)'52%  !PPROXIMATE -4) IMPROVEMENT FACTOR LIMITATION DUE TO PULSE 
 vol. 36,  pp. 1652-1660, 1958. 
 knots. These speeds,  known as blind speeds,  are where the targets move 0, ½, 1, 1½, . wavelengths  between consecutive transmitted pulses. 
 With the bias and missed detections, the peak of CS is lower than the other three methods. The time taken by the three algorithms is given in Table 2.T a b l e 2shows that the three algorithms take similar amounts of time. 35. 
 1343. PPI displays are ofthe rotating-coil type, and arepreferably arranged topermit off-centering. The rotating sweep coilisdriven byasize-5 synchro energized byasize-6 synchro connected tothe azimuth gear train inthe power console. 
 The signal time record is divided into two coordinates: fast time, measured on the range direction with index k(range sample number), and slow time measured in cross-range direction with index p(azimuth sample number). Thus, the ISAR signal microburst is registered in a three-dimensional array with discrete coordinates [ k,p,r]. In case all microbursts are used for aperture synthesis, the procedure is repeated for all remained microbursts inside the main pulse. 
 Acircularly polarized waveisoneinwhichtheelectricfieldvectorrotateswithconstant amplitude abouttheaxisofpropagation attheradarfrequency. Toanobserver lookinginthe direction ofpropagation, aclockwise-rotating electricfieldisknownasright-hand circular polarization, andacounterclockwise rotation isknownasleft-hand circular polarization. Right-hand andleft-hand circularpolarization aresaidtobeorthogonal polarizations sincean antenna capableofaccepting onewillnotaccepttheother.Similarly, horizontal andvertical linearpolarizations areorthogonal. 
 5. J. Rheinstein, “Backscatter from spheres: A short-pulse view,” IEEE Trans ., vol. 
 If H stands for linear horizontal polarization, 'V for linear vertical, and if the first  letter of a two-letter grouping denotes the transmitted polarization and the second ktter  denotes the polarization of the received signal, then the polarization matrix requires knowl­ edge of the amplitudes and phase of the following components: HH, VV, HV and V H. HV  and VH are sometimes called the cross polarization components. In general HV = VH so that  only one need be determined. 
 J. Roome, “Digital radio frequency memory,” Electronic & Communication Engineering  Journal , pp. 147–153, August 1990. 
 L.R..etal.:Terminology inDigital SignalProcessing, IEEETrans., vol.AU-20, pp.322-337.Decemher. 1972. 29.Cooley. 
 Included in this hardware are the antenna reflector, feed, gimbals, drive motors, gyros, digital shaft encoders, rotary joints, transmitter, receiver, upconverter, first downconverter, and fre- quency synthesizer. The inboard hardware is located internally to the shuttle and includes the signal-processing, track-filtering, and control functions. The Ku-band IRACS operates in the band of frequencies between 13.75 and 15.15 GHz, with radar operation between 13.75 and 14.0 GHz. 
 3.1. Datasets In this part, we will present our datasets. The SAR ship data set is derived from six full-size SAR images from TerraSAR-X stripmap mode, with a resolution of 2 ×1.5 m in the range and azimuth directions. 
 16.2] BASIC PRINCIPLES OF MTI. 628 MOVING-TARGET INDICATION [SEC, 162 FIG.16.2.—Successive 30-mile normal and MTI PPI photographs. Note storm echoes at10°at25miles, 60°at15miles, and 150° at30miles, Seven aircraft arc\-isihlc onthe \lTI PPI.. 
 56 This operation is called beam splitting. The moving-window detector has  no prior knowledge of the target beginning. It must be sufficiently sensitive to quickly detect a  region of increased density of ls, yet it must not be so sensitive that it initiates false alarms due  to noise. 
 £È°ÎÓ  2!$!2 (!.$"//+  &)'52%     'ENERAL LAND 
 BASED RADAR SOUNDERS HIGHLIGHTED IN 4ABLE  FALL NATURALLY INTO TWO  GROUPS SUBSURFACE AND ATMOSPHERICIONOSPHERIC )T IS EVIDENT THAT THE SUBSURFACE SOUNDERS ALL ARE AT RELATIVELY LOW FREQUENCY  IN CONTRAST TO THE ATMOSPHERIC SOUNDERS AT MUCH HIGHER FREQUENCY 4HE IONOSPHERIC SOUNDING MODE OF -!23)3 IS A SPECIAL CASE  ELABORATED BELOW 3UBSURFACE 3OUNDINGnFLIGHT 3YSTEMS  3UBSURFACE SOUNDING FROM A SPACE 
 For example, at X band (I,,, = 3 cm), Eq. (12.13)  predicts that the duct must be at least 10 m thick; at S band (I = 10 cm) it must be 22 m; and  at UHF (A = 70 cm), the duct thickness must be at least 80 m thick. (The value of -An/Ah  was taken as 1.57 x 10- m- I.) Since atmospheric ducts are not usually deep, extended range  propagation is more likely to be experienced at the higher microwave frequencies than at the  lower frequencies. 
 PROCESSOR THAT FOLLOW  4HIS LOSS CAN ALSO BE INCORPORATED INTO THE RECEIVER NOISE FIGURE VALUE 0ULSE #OMPRESSION -ISMATCH ,OSS  4HIS IS CAUSED BY THE INTENTIONAL MISMATCH 
 AP-5, pp. 81-90, January, 1957.  57. 
 RADIUS MODELS ARE THE 3TANDARD 0ROPAGATION -ODEL & 
 WAVE  PATHS SPANNING GREAT RANGES  THE GRAZING ANGLES TEND TO BE SMALL BETWEEN  AND   &OR THESE WAVELENGTHS AND GRAZING ANGLES  MEASUREMENTS BY #ROMBIE INDICATE THAT THE SCATTERING FROM THE SEA SURFACE WAS THE RESULT OF SCATTERING FROM SEA WAVES OF ONE 
 For 2 rough example let us say that the speed of radio  waves is 186,000 miles a second. One single burst of.  radio energy is transmitted, and it darts out into space  in all directions, one tiny fraction of this energy striking  the metal substance of an aircraft. 
 The large cross section and the close range can result in considerable altitude return. (_)1  The clutter illuminated by the antenna sidelobes in directions other than directly beneath  the aircraft may have any relative velocity from + v to -v, depending on the angle made by  the antenna beam and the aircraft vector velocity (v is the aircraft velocity). The clutter  spectrum contributed by these sidelobes will extend 2v/). 
 Coleman, “A general purpose ionospheric ray-tracing procedure,” DSTO Technical Report   SRL-0131-TR, 1993. 52. Jari Perkiömäki, “High-frequency (HF) ionospheric communications propagation analysis and  prediction,” VOACAP Quick Guide, http://www.voacap.com/. 
 OVER LOSS. £Ó°n  2!$!2 (!.$"//+  &OR FEEDS WITH CONDUCTING WALLS  THE EFFECTIVE ( 
 Unless all the reflections are collimated back at some central  point (or independent feeds are used), some of the reflected energy will generally be  re-reflected and contribute to undesirable sidelobes. For large arrays, the impedance of an element located near the center of the array  is often taken as typical of the impedance of every element in the array. As might  be expected, this element is most strongly influenced by elements in its immediate  vicinity. 
 SHAPED ARRAY OF  r  BICONICAL ELEMENTS RANDOMLY DISTRIBUTED r VERTICAL CURTAIN ARRAYS OF  MASTS r  VERTICALLY STACKED HORIZONTAL CAGE DIPOLES &REQUENCY  RANGE -(Z n  n  n n n n n 4X APERTURES M                   ARMS r  LONG  r  WIDE   4X AZIMUTH BEAM STEER DEG o no  no no  n  n 2X ARRAY DESIGN ,INEAR ARRAY  OF   
 15.27 Chebyshev FIR filter design with 68 dB doppler sidelobes. the antenna literature. An example of a Chebyshev filter design for a CPI of nine pulses and a sidelobe requirement of 68 dB is shown in Fig. 
 The reaction  time may be minutes or hours. The purpose is not to detect emitters as soon as they  switch on in the operational environment, but to provide detailed characteristics of  emitters to allow the generation of an identification database for RWR and ESM  systems. ELINT system sensitivity may reach –90 dBm, but they don’t need to pro - vide 360° surveillance, and they can reach such performance by means of several  directive antennas. 
 Angle- tracking-error detection (error demodulation) is accomplished by a pair of phase detectors using a reference input from the scan motor. The phase detectors per- form essentially as dot-product devices with sine-wave reference signals at the frequency of scan and of proper phases to obtain elevation error from one andTARGET BEAMA BEAM B BEAM A RETURNBEAMB RETURN RADAR(a)SCOPE PRESENTATION TARGET BEAM B BEAM A (b)BEAMA RETURNBEAMB RETURN . RADAR FIG. 
 ORIENTED AND THE  OVERALL DESIGN PHI 
   4HE )NSTITUTION OF %LECTRICAL AND %LECTRONIC  %NGINEERS  .EW 9ORK  .9   4HE AMBIGUITY FUNCTION IS DEFINED ON PAGE  USING THE STANDARD 
 Shall we increase Pinﬁnitely if we want to acquire more predicted signal? Of course not. The selection criteria of the AR model order is detailed discussed in [25,26], and the AR model order is set as one third of the data length in our experiment. Figure 4 gives the predicted energy ratio curve with the predictor factor. 
 PULSE TRANSMIT ENERGY  GIVEN  BY %T   0T4  THAT IS REQUIRED FOR TARGET DETECTION OR TRACKING 4HE RECEIVED ECHO  IS PROCESSED USING A PULSE COMPRESSION FILTER TO YIELD A NARROW COMPRESSED PULSE RESPONSE WITH A MAINLOBE WIDTH OF APPROXIMATELY " THAT DOES NOT DEPEND ON THE DURATION OF THE TRANSMITTED PULSE  &IGURE  SHOWS A BLOCK DIAGRAM OF A BASIC PULSE COMPRESSION RADAR 4HE CODED  PULSE IS GENERATED AT A LOW POWER LEVEL IN THE WAVEFORM GENERATOR AND AMPLIFIED TO THE REQUIRED PEAK TRANSMIT POWER USING A POWER AMPLIFIER TRANSMITTER 4HE RECEIVED SIGNAL IS MIXED TO AN INTERMEDIATE FREQUENCY )&  AND AMPLIFIED BY THE )& AMPLIFIER 4HE SIG 
 DENSITY PLOT MAY BE OBTAINED BY SQUARING THE ORDINATE VALUES OF A SPECTRAL 
 FSLOG       %FFECTIVE 
 The likelihood of overdetec­ tion of a target will depend on how the volume is scanned. To avoid this problem the detection  decision might have to be delayed until the neighboring beam positions have been scanned.  After a detection decision is made it must be correlated against existing tracks to determine  whether il is a new target or an existing Larget already in track. 
 If the FM-CW radar is used for single targets only, such as in the radio altimeter, it is not  necessary to employ a linear modulation waveform. This is certainly advantageous since a  siniisoidal or almost sinusoidal frequency modulation is easier to obtain with practical equip- ,:  ments than are linear modulations. The beat frequency obtained with sinusoidal modulation 1s  not constant over the modulation cycle as it is with linear modulation. 
 Pulse Compression Mismatch Loss.  This is caused by the intentional mismatch - ing of the pulse compression filter to reduce time (range) sidelobes. Eclipsing and Range Gate Straddle Loss. 
 12.10 of ref. 1.  !33. 
 Coherent beacons (which receive, amplify, and transmit received radar  pulses) can provide a doppler-shifted response free of target-caused spectral spread  and periodic modulations. A delay time is provided to separate the beacon response  from the target echo. Target doppler scintillation also offers useful information about the target configura - tion. 
 SPECIFIED ANTENNA TYPE  THE OPERA 
 This blind focusing could be very useful, for instance, for SAR systems onboard simple aerial unmanned vehicles to be used in real-time and low-cost applications. The algorithm performances were ﬁrst assessed through simulations, and then SAR data from the ERS mission were processed by using both the proposed algorithm and the standard Range Doppler focusing approach. Results showed a reasonably good quality of the focused image both in amplitude and phase. 
 SIGHT VELOCITY OF POINT " IS AWAY FROM THE RADAR 4HESE DETERMINE THE MINIMUM 02& OF  6$  WHERE  6   PLATFORM SPEED AND  $    ANTENNA PHYSICAL DIAMETER #OURTESY OF 3CI4ECH 0UBLISHING  )NC  . 
    SYSTEM IS A 5(& SOLID 
 For the brief duration ofthe modulator pulse, which may typically be1~sec, the magnetron oscillates atthe radio frequency forwhich itisdesigned, usually some thousands ofmegacycles persecond. The r-fpulse thus produced travels down the r-ftransmis- sion line shown bydouble lines inFig. 1.4, and passes through the two switches designated asTR and ATR. 
        ! !                  #     &)'52%  !PERTURE CONTROL FOR PLATFORM MOTION COMPENSATION.   !)2"/2.% -4)  Î°Ó MUST ALSO SPAN THE SPATIAL DIRECTIONS OF THAT INTERFERENCE !N EXAMPLE OF A SIMPLE  TRANSFORMATION OF THIS TYPE WOULD BE SIDELOBE CANCELER ARCHITECTURE WHERE THE BEAM TRANSFORMATION WOULD GENERATE A SUM CHANNEL MAIN BEAM AND SELECT ELEMENTS FROM THE APERTURE AS SIDELOBE CANCELLERS 0OST 
 Use of a common aerial for reception and transmission  (a standard technique now in centimetric radar systems)  involves some form of switch to insulate the receiver  from the great surge of energy when the transmitter  ‘fires,’ and to connect the receiver to the aerial in good  time (although it may be only.a minute fraction of time, -  perhaps a millionth of a second) for reception of the  echo. The pulse is received, then amplified at radio  frequency, probably by a superheterodyne arrangement  which obeys conventionality in principle, even though  the circuit and component values may be unorthodox  . ‘IMPOSSIBLE’ CIRCUITS 85  compared with broadcast practice. 
 TFTPCF curves with different CkL.(a) TFTPCF versus frequency separation. ( b) TFTPCF versus spatial separation. 187. 
 Obviously, the effect is reciprocal for  both transmit and receive paths. For a point target and a sea of defined roughness, the  calculation to determine the resultant effect is relatively straightforward and results  in the classic lobing pattern (see, for example, Briggs8). For a target with reasonable  vertical extent, such as a ship, the lobing structure becomes very complex and is less  likely to produce troublesome nulls. 
 CALLED AREA -4)  AND MANY ATTEMPTS  HAVE BEEN MADE TO IMPLEMENT AN EFFECTIVE VERSION OF THIS CIRCUIT OVER AN EXTENDED SPAN  OF TIME 4HE MAIN HINDRANCE TO ITS SUCCESS HAS BEEN THE LACK OF APPROPRIATE MEMORY TECHNOLOGY  SINCE THE STORAGE TUBE LONG THE ONLY VIABLE CANDIDATE  LACKS IN RESOLUTION  REGISTRATION ACCURACY  SIMULTANEOUS READ 
 V. Hoover: Gas Tuhes Protect High-Power Transmitters, Electronics, vol. 29,  pp. 
 flood beam that permits a bright; persistent display of the  information carried by the writing beam. The writing beam does not impinge directly on the  viewing screen as in a conventional CRT. It strikes a storage mesh, mounted just behind the  screen, made up of a thin film of insulator material deposited on a metallic backing electrode. 
 The orbit parameters include repeat period 9.9156 calendar days (unfortunately, often  stated as 10 days); inclination 66 °; repeat track separation at the equator (316 km); and  altitude 1336 km. The radial component of precision orbit determination (POD) is on  the order of 2 cm for T/P, and Jason-1 results show POD to a level of 1.5 cm. Although  these parameters reflect the fruits of multiple years of trade studies by many individu - als,63 at least one unwanted characteristic remains. 
 56. D. Mooney, “Post-Detection STC in a Medium PRF Pulse Doppler Radar,” U.S. 
 This follows from the properties of the Fourier  transform. Therefore a finite spectrum must of necessity be transmitted if transit time or range  is to be measured.  The spectrum of a CW transmission can be broadened by the application of modulation,  either amplitude. 
 TARGET SITUATIONS v  )%%% 4RANS  VOL !%3 
 The elevation angle of the target is determined by which receiver is excited.  This technique has been called withi11-1wlse scanning.  The height resolution depends on the antenna beamwidth, as in a conventional frequency­ scan antenna; but the range resolution is determined by the frequency spectral components. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 which focused on the spatial distribution of electron density, were used extensively  in early HF radar performance analyses and include ITSA-1, ITS-78, RADAR C,  IONCAP, and AMBCOM.27–32 Lucas 33 provides details of these models and their  origins. 
 Near the ground tlie convective cells might be a few tens of  meters in diameter. As tlley rise, tiley grow in size and can reach a diameter of 1 to 3 krn. They  rise until they lose buoya~icy or until they reacli a level wliere condensation takes place. 
 Both beams have the same amplitude (voltage) distribution  F(x) but differently inclined linear phased fronts. The total aperture excitation with  both beams is  F x F x e F x e F xj x a j x a( , ) ( ) () () c( / ) (/ )ψψ ψ= + =2 21 2 2 o os( )( ) ( / )ψ ψψ ψ 1 21 2 −  + x aej x a  That is, the aperture amplitude distribution required for two separate beams varies  cosinusoidally, and the phase distribution is linear and has the average inclination. In most phased array systems, only the phase can be controlled. 
 The distribution of electromagnetic energy in three- dimensional angular space, when plotted on a relative (normalized) basis, is called the antenna radiation pattern. This distribution can be plotted in various ways, e.g., polar or rectangular, voltage intensity or power density, or power per unit solid angle (radiation intensity). Figure 6.1 shows a typical radiation pattern for a circular-aperture antenna plotted isometrically in terms of the logarithmic power density (vertical dimension in decibels) versus the azimuth and elevation angles in rectangular coordinates. 
 BAND  LINEAR ARRAYS ARE USUALLY CONSTRUCTED AS  CONTIGUOUS COLLINEAR ARRAYS . Óä°£Ó  2!$!2 (!.$"//+  *INDALEE  3TAGE "*/2. 
 2. Radar: Principles, Technology, Applications -Byron Edde, Pearson Education, 2004.   3. 
 6. Lerner, R. M.: A Matched Filter Detection System for Complicated Doppler Shirted Signals,  pp. 
 17. Peebles, P. Z .. 
 SEC. 10.9] THE HARD-TUBE PULSER 369 care inprocessing and useitispossible, nevertheless, toarrive atasatis- factory and highly flexible pulser desigu using the oxide-cathode pulse tube upto20kv. Where extreme reliability and relative immunity to overload are required, the designer will prefer the thoriated-tungsten cathode switch tube inspite ofitsgreater cathode power requirements. 
 Either electro- static orelectromagnetic means ofenergy storage can beused. Inthelatter case, energy stored inthemagnetic field ofaninductance through which current isflowing isreleased totheload bysuddenly inter- rupting the current. This can beachieved bybiasing tocutoff ahigh- vacuum tube inseries with theinductance, theresulting inductive voltage rise being applied tothe load. 
 as shown by the dashed line. A target is said to be detected if the envelope crosses the  threshold. If the signal is large such as at A, it is not difficult to decide that a target is present. 
 CIES  INCLUDING MIXED PULSE LENGTHS AND BURSTS OF PULSES WITH CLOSE PULSE SPACINGS -ICROWAVE TUBES AND THEIR HIGH 
 Atthe receiving station, the signals pass through aduplexer totwo receivers. The first delivers thetime-shared MTI and lower-beam video signals, together with markers, directly tothe indicators. Signals from 1The circuit details ofthe equipment actually tested differ considerably from those ofFigs. 
 10.25. Toachieve the final pulse current 1,thepulser must beadjusted toavalue ofVOconsiderably higher than the starting voltage Vs. Under proper conditions, when thepulse isapplied tothe magnetron, the V-1curve isthat shown dotted inFig. 
 Nat. Conf. Aeronaut. 
 OFF ABOVE THE HORIZON AND A TAPERED PATTERN BELOW %NERGY DIRECTED ABOVE THE HORIZON INCREASES PRECIPITATION CLUTTER AND ALSO REDUCES THE ANTENNA GAIN !T ANGLES BELOW THE HORIZON  THE GAIN SHOULD NOMINALLY FOLLOW A COSECANT SQUARED POWER LAW 4HIS IS AIMED AT GIVING A CONSTANT SIGNAL  STRENGTH FROM A TAR GET OF FIXED 2#3  INDEPENDENT OF RANGE  4HESE ARE OFTEN KNOWN AS  INVERTED OR  INVERSE COSEC SQUARED ANTENNAS TO DIFFERENTIATE  THEM FROM AIR TRAFFIC CONTROL RADAR ANTENNAS THAT HAVE THEIR SHAPING AT ANGLES ABOVE THE HORIZON 3UCH SHAPING OPTIMIZES THE PATTERN TO THE APPLICATION  GREATLY ENHANCING OVER 
 (21.26) that the autocorrelation function of g rather than g itself determines the range resolution of the system. A variety of waveforms have been used to achieve range resolution. Among them the two most important are those in which g(t) is a short pulse and those in which g(t) is a linearly frequency-modulated short pulse (chirped signal). 
 DIMENSIONAL  WORLD IS REASONABLY EFFECTIVE MOST OF THE TIME  THE DIFFRACTION COEFFICIENTS INCONVE 
 DIMENSIONAL CONDUCTING  RANDOM ROUGH SURFACES v  )%%% 4RANS ON 'EOSC AND 2EMOTE 3ENSING  VOL   PP n      7 ( 3TILES  $ "RUNFELDT  AND & 4 5LABY  h0ERFORMANCE ANALYSIS OF THE -!3 -ICROWAVE  !CTIVE 3PECTROMETER  SYSTEMS CALIBRATION  PRECISION AND ACCURACY v 5NIVERSITY OF +ANSAS   2EMOTE 3ENSING ,AB  VOL 42  
  D COS PSQ  &OR EXAMPLE  IF  2G    KM   (    KM  H    M  AND  PSQ     THEN D    M    X   X  AND Y   Y n  M 4HE TOWER TOP APPEARS IN THE IMAGE  M CLOSER TO THE RADAR  THAN THE TOWER BASE 4HIS PRINCIPLE MAY SOMETIMES BE USED TO ESTIMATE THE HEIGHT OF ISOLATED  TOWER 
 175. Sensors 2018 ,18, 3750 Figure 17. InISAR imaging results of ﬁve metal balls with 20% data. 
 However, itmayhe shownthattheaverage beatfrequency measured overamodulation cycle,whensubstituted intoEq.(3.11)yieldsthecorrectvalueoftargetrange.Anyreasonable-shape modulation waveform canbeusedtomeasure therange,provided theaverage beatfrequency is measured.28,29Iflhetargetisinmotionandthebeatsignalcontains acomponent duetothe doppler frequency shift,therangefrequency canbeextracted, asbefore,iftheaverage frequency ismeasured. Toextractthedoppler frequency, themodulation waveform musthave equalupsweep anddownsweep timeintervals. TheFM-CW radarprinciple wasknownandusedataboutthesametimeaspulseradar, although theearlydevelopment ofthesetworadartechniques seemedtoberelatively indepcn­ dentofeachother.FM-CW wasappliedtothemeasurement oftheheightoftheionosphcre in the1920S32andasanaircraftaltimeter inthe1930s.33 FM-CW altimeter. 
 A decoy is a srnall aircraftlike vellicle made to appear to the radar as a realistic target. If  tlie decoy and the aircraft are made indistinguishable to tlie radar, the radar operator may bc  deceived into thinking the decoy is hostile and commit a weapon to attack. If sufficient decoys  ;\re present, the defense system could be overloaded. 
 The sharp increase in loss just before 2000 nmi is caused by transition from one to two hops; for two hops the lossy D region is transited twice as many times, ground-reflection loss is added, and required operation at a lower frequency in- creases loss. The jagged curve in the transition region is due to the parameter selection process; in radar operation the frequency would be selected to minimize transition effects. The frequency, radiation angle, and noise power per hertz that go with this site and look direction are also plotted. 
 D. Belville, and W. Benner, “The national weather radar testbed (phased  array),” presented at 18th Int. 
 Comparison of elevation antenna patterns for ASV Mks. VI and III.Airborne Maritime Surveillance Radar, Volume 1 4-3. 4.2.3 Transmitter receiver TR3519 The transmitter used a CV192 magnetron, outputting a typical peak power of 200 kW. 
 Ryde23 studied the attenuation of microwaves by rain and deduced, by using Laws and Parsons24 distributions, that this attenuation in decibels per kilometer can be approximated by KR = J^r° [R(r)Tdr (23.18) where KR = total attenuation, dB K = function of frequency25 R(r) = rainfall rate along path r r0 = length of propagation path, km a = function of frequency10 Medhurst26 shows that a = 1 is a good assumption in many cases. The path loss per mile, according to Ryde, for the three carrier frequency bands of 4, 6, and 11 GHz, is shown in Fig. 23.1. 
 12.13  Effect of Detection  .............................................  12.16  Moving Target Surfaces  .....................................  12.18  12.5 Measurement Techniques for Ground Return   ........ 
 9.13. The AN/APQ-7 (Eagle) Scanner.-The AN/APQ-7 (Eagle) high-resolution navigation and bombing equipment was developed at Radiation Laboratory; Bell Telephone Laboratories carried through the production engineering. I The antenna developed forthis equipment produces atthe3-cm band ahorizontally polarized beam ofradiation which has awidth of0.4° to 0.5° inazimuth and isshaped inelevation togive anapproximately cosecant-squared coverage down to70°angle ofdepression. 
 When radars are looking at a normal-incidence angle, horizontally polarized waves are reflected better by horizontal wires, rails, etc., than are vertically polarized waves. If the geometry of two radar targets were the same, the returns would be . stronger from the target with higher complex permittivity because larger currents (displacement or conduction) would be induced in it. 
 Sidelobe Suppression with Resolution Maintenance for SAR Images via Sparse Representation. Sensors 2018 ,18, 1589. [ CrossRef ][PubMed ] ©2019 by the authors. 
 A consideration of the geometry involved shows that the phase correction that must be applied is a function of depression angle. Consequently, the correction must be made as a function of range. The rate of change correction is very rapid at steep depression angles and becomes slower at shallow depression angles. 
 Ulaby and M. C. Dobson, Handbook of Radar Scattering Statistics for Terrain , Norwood,  MA: Artech House, 1989. 
 PLER RADARS THAT EMPLOY DIGITAL SIGNAL PROCESSING ARE DISCUSSED BELOW 3OME OF THE LOSSES MAY BE INCORPORATED INTO THE OTHER VARIABLES IN THE RADAR RANGE EQUATION #ARE MUST BE TAKEN TO ACCOUNT FOR ALL OF THE SYSTEM LOSSES WHILE AVOIDING REDUNDANCIES . {°{ä  2!$!2 (!.$"//+  -OST FRONT 
 The presence of the subreflector in front of the main reflector in the Cassegrain  configuration causes aperture blocking. Part of the energy is removed, resulting in a reduction  of the main-beam gain and an increase in the sidelobes. If the main reflector is circular and  assumed to have a completely tapered parabolic illumination, a small circular obstacle in the  center of the aperture will reduce the (power) gain by approximately [1 -2(Db/D)2]2, where  D,, is the diameter of the obstacle (hyperbolic subreflector) and Dis the diameter of the main  aperture.19 The relative (voltage) level of the first sidelobe is increased by (2D,./D)2. 
 .·.  ~.·. -;.·'.·:~'('. 
   PP n  *ANUARY    2 # (ANSEN  h!PERTURE THEORY v IN  -ICROWAVE 3CANNING !NTENNAS   VOL )  2 # (ANSEN ED    .EW 9ORK !CADEMIC 0RESS    CHAP    ( 'AUTIER AND 0 4OURNOIS  h3IGNAL PROCESSING USING SURFACE 
 57. L. Solomon, “Radar cross section measurements: How accurate are they?” Electronics , vol. 
 The AirMinistry asked that 30such systems beinstalled inaircraft inthenext 30days. Before the end ofSeptember allthese systems had been installed, four having been ready ontheday war broke out. Emphasis onairborne radar underlined thepoint that, ifsharp radar beams were ever tobeproduced byantennas small enough tocarry inan ~Plane, wavelengths shorter than the 1+mused inearly British air- borne equipment would have tobeemployed. 
 SUPPORTED WIRE 
 LENT TO THE RESULT OBTAINED BY THE 30- DISCUSSED ABOVE  AND ALTHOUGH IT IS SOMETIMES FELT THAT ITS DERIVATION FROM A SURFACE INTEGRAL PROVIDES SOME POTENTIAL FOR GREATER GENERALIZATION  IT CARRIES WITH IT ALL OF THE SAME RESTRICTIONS "EFORE PROCEEDING FURTHER  IT IS INSTRUCTIVE TO LOOK A LITTLE MORE CLOSELY AT THE IMPLI 
  
 Assume forthepresent that theenergy-storage element isa condenser, Co,charged toapotential Vcsothat the energy stored is ~COV~. 1$’hen theswitch S’isclosed atL=O,thecondenser will begin discharging exponentially through theload resistance R..Iftheswitch S can now beopened suddenly atatime tOvery small compared tothetime constant RLCOofthe circuit, the voltage appearing across the load, for O<t<h,will begiven by. SEC. 
 However, asthe azimuth pulse moves back and forth intime with respect tothe switching pulses, the coincidence times vary inanout-of-phase manner sothat thepotential ofClhasastepwise variation with asinusoidal envelope (Waveform I). This alternating signal ispassed through cathode follower VGb and abandpass filter in order toproduce thedesired sinusoid fordriving thesynchronous motor. Inorder tominimize thenumber oftransmitted pulses, thebasic pulse can berelated tothemodulator pulse inany ofseveral ways. 
 Residual motion error correction with back-projection multi-squint algorithm for airborne synthetic aperture radar interferometry is applied in [ 20]. An object’s movement of higher order as different kinds of accelerations and range displacements causes the ISAR image to be blurred, which requires focusing the object. An autofocusing method for improving synthetic aperture radar image quality and modified fractal signature image classification technique are described in [ 21]. 
 LOOKS  WITH NO INCREASE IN AVERAGE DATA RATE OR  TRANSMITTED POWER .OTE THAT ALL OF THESE AMBIGUITY 
 In land scenarios variable terrain can decrease clutter levels by masking a clutter LOS when L < rR + rT or increase clutter levels by generating a clutter LOS when L > rR + rT. When the transmitter and/or the receiver is elevated or airborne, LOS restric- tions are greatly reduced but not necessarily eliminated. Two clutter problems unique to bistatic radars are encountered in this situation. 
 CHAPTER  TWO  THE RADAR EQUATION  2.1 PREDICTION OF RANGE PERFORMANCE  The simple form of the radar equation derived in Sec. 1.2 expressed the maximum radar range  Rmu. in terms of radar and target parameters:  [ P,GAecr] ''4  Rmu = ( )2 4n Sm1n  where P1 = transmitted power, watts  G = antenna gain  A, = antenna effective aperture, m2  <1 = radar cross section, m2  Smin = minimum detectable signal, watts (2.1)  All the parameters are to some extent under the control of the radar designer, except for the  target cross section cr. 
 (14.36)] However, the total variation (dynamic rhnge) of the  received signal with target position is not as pronounced with bistatic radar as with monostatic  radar. In bistatic radar. as either D, or D, decreases, the other increases. 
 An integral part of an HF radar is a channel occupancy analyzer that provides a real- time description of spectrum availability. 24.9 SKY-WAVE TRANSMISSION MEDIUM Solar radiation and particle emission bombardment are the cause of ionization in the earth's upper atmosphere. Even though there is no incident radiation at night, the ionization never completely decays; that is, there is always an ionosphere. 
 This isnecessary toprevent (1)uneven illumination ofthe area being scanned, (2)loss ofradar range, or(3)distortion ofthePPI presentation. Stabilization equipment must bedesigned and constructed tostabilize thebeam ofradiation, whether itbepencil orfan, against any maneuver oftheaircraft such asaclimb, aglide, orany combination thereof. This must beaccomplished with components that are not affected bythe various accelerations, attitudes, orvibrations which might beencoun- tered inturns, climbs, glides, orbanks. 
  CONFIGURATION %ACH OF THE FOUR FINAL STAGES DELIVERS  7 PEAK FOR  
 SIDED BANDWIDTH  " IS PLOTTED ON A LONG  PIECE OF PAPER  AS SHOWN IN &IGURE  A )N THE FIGURE  THE POSITIVE 
 With circular polarization, the signal returned from a single-bounce target will require an antenna matched to the opposite sense of circular polarization from that transmitted. If the same antenna is used, then single-bounce targets are re- jected. Such a system can therefore give a measure of suppression of rain echoes,28 ideally amounting to 20 log (e2 + l)/(e2 - 1) dB where e is the voltage-ellipticity ratio. 
 This allows much greater simplicity and flex- ibility. A triple-mode two-horn feed used by RCA7'8 retracts the /s-plane septa to allow both the TE10 and TE30 modes to be excited and propagate in the double- width septumless region as illustrated in Fig. 18.12. 
 Ê 
 A., J. A. Lane, R. 
 InSAR Data Validation by Using Leveling Benchmarks The InSAR results are validated by 56 leveling benchmarks. Among these leveling benchmarks, a stable one located at East Lake Peony Garden (30◦34/prime27” N, 114◦21/prime57” E) is used as a reference point to measure land subsidence. Four parameters, namely, maximum discrepancy (MaxD), minimum discrepancy (MinD), mean absolute discrepancy (MD), and root mean square (RMS), are used to describe the reliability of SBAS-InSAR derived land subsidence rate map. 
 Inthisdevice,neitherthebrightness northepersistence isdirectlyaffected bythe shortduration ofthevideosignal,orbythecharacteristic oftheviewing-screen phosphor.. 358 INTRODUCTION TO RADAR SYSTEMS  The storage tube uses two electron beams generated by separate electron guns. One is a  writing beam. 
 22,   pp. 80–107, January 1943. 38. 
 INCIDENCE SCATTERING COEFFICIENTS THAT ARE TOO SMALL  4HIS IS A CONSEQUENCE OF A FUNDAMENTAL PROBLEM IN MEASURING NEAR THE VERTICAL WITH A FINITE BEAMWIDTH OR PULSE  LENGTH .EAR 
 It can be shown from geometrical optics considerations that a spherical wave emerging from F and incident on the reflector is transformed after reflection into a plane wave traveling in the positive z direction (Fig. 6Ab). The two coordinate systems that are useful in analysis are shown in Fig. 
 Shrader32  © IEEE 2007 )0 20 3 0 4 0 5 0 6 00510152025|Residue| (Volts) (a) 10 0 20 3 0 4 0 5 0 6 002040608010I3 Per Pulse (dB) Pulse Number (b) ch02.indd   64 12/20/07   1:45:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 It was not until the advent of the Leigh Light that successful illumination would be achieved. The Leigh Light was a 22 million Candela carbon arc searchlightwith 24 inch diameter that could be steered in azimuth and elevation when homing onto a target. This was ﬁrst deployed in June 1942 in LRASV Wellingtons of No. 
 )are presented inFig. 3.27. This particular photograph was obtained with aso-called “three-tone” presentation (Sec. 
 75. W. I. 
 MENTS 2ESEARCH RADARS EXPLORE THE DEPOLARIZATION RATIOS BY ALTERNATING HORIZONTALLY AND VERTICALLY POLARIZED PULSES (OWEVER  THE PREFERRED CONFIGURATION FOR OPERA 
 Gunn, K. L. S., and J. 
 G.: Performance of the Analog Moving Window Detector, IEEE Trans., vol. AES-6,  pp. 173-179, March, 1970. 
 Radar Aperture Datalinking.81 Historically, datalink functions embedded in  MFARs have been used for the midcourse guidance of missiles. An emerging applica - tion is the use of the radar aperture as a high power, high gain primary datalink antenna,  Link Freq Band Data Rate (kb/s) ECCM ARC-164 UHF 1.8 High ARC-126 UHF 1.8 High ARC-201 VHF    8 Moderate ARC-210 VHF/UHF    8 Moderate–High TADIL UHF-L 1.8–56.6 Moderate–High JTIDS L 28.8–56.6 Moderate JTIDS LET L 383.6–1,180.8 Moderate JTRS VHF-X 1.8–1,544 Moderate–High TADIXS UHF 9.6 Moderate MFAR X-Ku 2–105 Moderate–High Milstar UHF, Ku - Ka 4.8–1,544 High TCDL X - Ku 1,000–256,000 ModerateTABLE 5.3 Air Data Links80 ch05.indd   25 12/17/07   1:27:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
     P   -AY   0 7 (ANNAN  h4HE ULTIMATE DECAY OF MUTUAL COUPLING IN A PLANAR ARRAY ANTENNA v  )%%% 4RANS   VOL !0 
 TION LEAD TO DISCONTINUITIES THAT MAY BE PERIODIC AND GIVE RISE TO  QUANTIZATION LOBES THAT  ARE SIMILAR TO GRATING LOBES !MPLITUDE OR PHASE ERRORS THAT VARY COSINUSOIDALLY MAY BE ANALYZED SIMPLY AFTER  "ROWN &IGURE A SHOWS AN ORIGINAL AMPLITUDE DISTRIBUTION  &X  DISTURBED BY A  COSINUSOIDAL RIPPLE Q COS O  XS   GIVING A NEW DISTRIBUTION &  ` X  SUCH THAT  `     &X & X Q& XX S &XQ&XEJX S     C O S     P P       §©¶¸ 
 E1G1 Aev *4max = 1 (1-5)(4^kT0Fn(EIN0) where Et = Pti is the energy contained in the transmitted waveform. Although Eq. (1.5) assumes a rectangular pulse, it can be applied to any waveform pro- vided that Et is interpreted as the energy contained in the transmitted waveform and that the receiver of noise figure Fn is designed as a matched filter. 
 ANE-8, pp. 7-19, March, 1961.  10. 
 C., and J. Frank: Array Antennas, chap. 11 of" Radar Handbook," M. 
 Adjacent quarter-wavelength-spaced loading-susceptances are equal  and take either of two values. If the magnitude of the normalized susceptance is small, the  reflection from any pair of symmetrical susceptances can be made to cancel so that matched  transrnissiorl will result for either of the two susceptance conditions. Each pair of diodes  spaced a quarter-wavelength apart produces an increment of the desired phase. 
 It should be noted that the concept of an element pattern that applies equally to every element is valid only when isolating feeds are used and edge effects are ignored. A thinned array may also be implemented with an irregular element spacing, although this is not common. In this case the element gain (and impedance) will vary from element to element, depending upon the environment of a given ele- ment. 
 Keeler, and G. G. Sanford: The Seasat-A Synthetic Aperture Radar Antenna, Synth. 
 Lno:SameforLband.. 44 INTRODUCTION TO RADAR SYSTEMS  Table 2.2 Example radar cross sections at microwave frequencies  Square meters  Conventional, unmanned winged missile  Small, single engine aircraft  Small fighter, or 4-passenger jet  Large fighter  Medium bomber or medium jet airliner  Large bomber or large jet airliner  Jumbo jet  Small open boat  Small pleasure boat  Cabin cruiser  Ship at zero grazing angle  Sliip at higher grazing angles  Pickup truck  Automobile  Bicycle  Man  Bird  Insect 0.02  2  10  See Eq. (2.38)  Displacement tonnage  expressed in m2  where o = radar cross section in square meters, f = radar frequency in megahertz, and D is the  ship's (full load) displacement in  kiloton^.^' This expression was derived from measurements  made at X, S, and L bands and for naval ships ranging from 2000 to 17,000 tons. 
 Zadeh, L. A., and J. R. 
 ING OF $       WAS USED  BUT THIS COULD BE REDUCED IN ORDER TO MINIMIZE  DOPPLER STRADDLING LOSSES 4HE THIRD FILTER IN THE FILTER BANK IS SHOWN IN &IGURE    &)'52%  $OPPLER FILTER DESIGN CONSTRAINTS        
 The ARSR-3 contains provision for switching in or out various processing features. A  range-azimuth generator (RAG) permits the selection to be made on the basis of both range  and azimuth. Among the features that might be selected by range and azimuth are included the  choice of MTJ or normal (Iog-CFAR) video, two STC control curves (one optimized for  terrain clutter, the other for sea clutter), the crossover range in switching from the upper to the  lower beam, fixed pulse-repetition period (for eliminating second-time-around clutter) or  variable pulse periods, different RF receiver gains, and sectors for transmitter blanking to  avoid RFI. 
 43. 46. p. 
 Appl. Phys., vol. 24,  pp. 
   PP n     3 * !NDERSON AND 9) !BRAMOVICH  h! UNIFIED APPROACH TO DETECTION  CLASSIFICATION AND  CORRECTION OF IONOSPHERIC DISTORTION IN (& SKYWAVE RADAR SYSTEMS v  2ADIO 3CIENCE  VOL    PPn  *ULYn!UGUST    $ " 4RIZNA  h%STIMATION OF THE SEA SURFACE RADAR CROSS S ECTION AT (& FROM SECOND 
 (The term transceiver is an acronym composed from thewords TRANSmitter and reCEIVER.) Modulator The function of the modulator is to insure that all circuits connected with the radar system operate in a definite time relationship with each other and that thetime interval between pulses is of the proper length. The modulatorsimultaneously sends a synchronizing signal to trigger the transmitter and theindicatorsweep.Thisestablishesacontrolforthepulserepetitionrate(PRR)andprovidesareferenceforthetimingofthetravelofatransmittedpulsetoatargetand its return as an echo. Transmitter The transmitter is basically an oscillator which generates radio-frequency (r-f) energy in the form of short powerful pulses as a result of being turnedon and off by the triggering signals from the modulator. 
 L. Mitchell and J. F. 
 The broadside linear-array antenna  rnay be used where broad coverage in one plane and narrow beamwidth in the orthogonal  plane are desired. The linear array can also act as a feed for a parabolic-cylinder antenna. The  colnbinatiotl of the linear-array feed and the parabolic cylinder generates a more controlled  fan beani than is possible with either a simple linear array or with a section of a parabola. 
 POLARIZED SIGNAL FOR LINEAR TRANSMISSION  BUT SOME FOR CIRCULARLY POLARIZED TRANSMISSION &OR THE PARK SHOWN IN &IGURE B   THE VERTICALLY POLARIZED LINEAR SIGNAL IS SLIGHTLY  HIGHER THAN THE HORIZONTALLY POLARIZED ONE 4HERE IS SOME CROSS 
 vol. AP-22, pp. 582-584, July, 1974. 
 ,,. :,, , .. 1 , :· . 
 In the inverted coaxial magnetron the cathode surrounds the anode. The stabilizing TE011  cavity is in the center of the magnetron with a vane-type resonator system arranged on the  outside. The cathode is built as a ring surrounding the anode. 
 If such a frequency error exists, the ranges read from the radargenerally are in error by some small percentage of the range. To reduce range errors caused by frequency drift, precision oscillators in radars usually are placed in a constant temperature oven. The oven is alwaysheated, so there is no drift of range accuracy while the rest of the set iswarming up. 
 This assumption isfalse since there isindirectly such aninfluence. The exact expression forWiscumbersome but this isoflittle practical con- sequence since itneed not beused. The two values obtained from Eqs. 
 H. Kneer: Noise Performance of Microwave GaAs  F.E.T. Amplifiers at Low Temperatures, Electronics Letters, vol. 
 BASED AFTER * 7URMAN  Ú )%%%    
 A short pulse has a wide spectral width (bandwidth). The effect of a short pulse can be obtained with a long pulse whose spectral width has been increased by phase or frequency modulation. When passed through a matched filter, the output is a compressed pulse whose duration is approximately the reciprocal of the spectral width of the modulated long pulse. 
 STATE MODULATORS OFFER IMPROVED TRANS 
   2!$!2 #2/33 3%#4)/.   £{°£ 4HE METHOD OF MOMENTS HAS BECOME A POWERFUL TOOL IN THE PREDICTION AND ANALYSIS  OF ELECTROMAGNETIC SCATTERING  WITH APPLICATIONS FOR ANTENNA DESIGN AS WELL AS 2#3  PREDICTION 4HIS METHOD HAS THREE LIMITATIONS  HOWEVER &IRST  BECAUSE COMPUTER MEMORY AND PROCESSING TIME BOTH INCREASE RAPIDLY WITH  THE ELECTRICAL SIZE OF THE OBJECT  THERE MIGHT BE AN ECONOMIC LIMIT FOR THE MAXIMUM  TARGET ELECTRICAL SIZE IN WAVELENGTHS  FOR WHICH -/- CAN BE USED 3ECOND  -/- YIELDS NUMBERS  NOT FORMULAS  AND IS THEREFORE A NUMERICAL EXPERIMENTAL TOOL (OWEVER  TRENDS MAY BE ESTABLISHED BY RUNNING THESE NUMERICAL EXPERIMENTS REPEATEDLY FOR PARA 
 Apart from the requirement to meet emission guidelines laid down by national  and international spectrum management authorities, high spectral purity is essential  because skywave radar uses doppler processing to separate the targets from the clut - ter, and hence, the clutter returned on the phase and amplitude noise sidebands radi - ated by the transmitter must be kept below the echo power of desired targets. This  can impose a stringent condition on the emitted signal-to-noise ratio of the transmit - ter, and hence, on the signal-to-noise ratio of the waveform generator. For example,  noise spectral density at 10 Hz from a carrier may need to be as low as –100 dBc in  order to detect some targets of interest. 
 2–6, January 1967. ch07.indd   54 12/17/07   2:15:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 LATION (OWEVER  A QUADRATURE SPLITTER NETWORK  IE  A POWER DIVIDER THAT PROVIDES A  D" SPLIT AS WELL AS A  n PHASE OFFSET  CAN BE USED TO PROVIDE A CONSTANT IMPEDANCE  AT THE INPUT TO THE SPLITTER REGARDLESS OF THE INDIVIDUAL AMPLIFIER INPUT IMPEDANCES &IGURE   4HIS ENSURES THAT A DRIVER AMPLIFIER STAGE IS PRESENTED WITH A WELL 
 Changing the relative  time phase between the sampling pulse train and the array output results in observing a  different angular direction. Thus the beam can be steered by varying the time phase of the  control Randposs filler  Figure 8.29 Within-pulse scanning using frequency-multiplexed linear array. This implementation  been called MOSAR. 
 Appl. MeteoroL, vol. 9, pp. 
 333–337. ch07.indd   57 12/17/07   2:15:11 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 4,Theangle formed bytheadvancement oftheground edges from KtoK’(Aq$) depends ontheangle Oofelevation ofthetarget T. ofinformation provided isachieved inamore subtle and, under the circumstances, amore effective way. The V-beam principle permits asingle scanning radar to give height as well as range and azimuth ofaircraft. 
 GROUND ECHO  16.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Many systems use digital waveform synthesis to obtain the swept waveform. If  dual antennas are used (as shown), the overlap of the beams must be considered.98  Single-antenna systems are sometimes used, with a circulator isolating transmitter  and receiver; their performance is somewhat poorer than that of dual-antenna systems  because of internal reflections and leakage through the circulator. Figure 16.21 shows the kind of system that may be used to measure scattering from  within a volume. 
  D" DOWN  FROM THE MAIN BEAM AVERAGE LEVEL  BELOW  
 FORMATION IN THE COURSE OF IONOSPHERIC PROPAGATION GREATLY REDUCES THE POSSIBLE UTILITY OF BEING ABLE TO MEASURE THE POLARIZATION STATE OF THE SIGNALS ARRIVING AT THE RECEIVING ARRAY 4HIS IS AN OPEN QUESTION AT THIS TIME  THOUGH EXPERIMENTS AIMED AT ASSESSING SKYWAVE RADAR POLARIMETRY ARE UNDERWAY  2ECEIVERS 4HERE ARE MANY DEMANDS ON THE RECEIVERS FOR /4( RADAR  INCLUDING  HIGH DYNAMIC RANGE  LINEARITY  WIDE BANDWIDTH  AND UNIFORMITY BETWEEN RECEIVERS WHEN USED IN MULTIRECEIVER SYSTEMS &OR MOST CIVIL AIRCRAFT AND SHIPS  TARGET RADAR CROSS SECTION 2#3  AT (& IS ROUGHLY OF THE SAME ORDER AS THE MICROWAVE 2#3  THAT IS  ^n D"SM FOR AIRCRAFT AND ^n D"SM FOR SHIPS  BUT THE RANGE IS n TIMES GREATER  SO THE EXTRA LOSS ASSOCIATED WITH 2 n IS IN THE RANGE n D" -OREOVER  EACH  TARGET ECHO IS IMMERSED IN CLUTTER FROM THE ILLUMINATED FOOTPRINT  WHICH MAY HAVE AN AREA OF MANY THOUSANDS OF SQUARE KILOMETERS &URTHER  THE (& SIGNAL ENVIRONMENT INCLUDES ONE 
 (2) ArcSAR Image 1 and ArcSAR Image 2 are used for interference to obtain interferometric phase. (3) We perform the operations of ﬂat phase removing and phase unwrapping for the interferometric phase. (4) The unwrapped interferometric phase is used to inverse the DEM of the scenes. 
 The  filter thresholds are determined by multiplying the mean levels by an appropriate constant to  obtain the desired false-alarm probability. This application of an adaptive threshold to each  doppler filter at each range cell provides a constant false-alarm rate (CFAR) and results in  strbweather visibility in that an aircraft with a radial velocity sufficiently different from the rain  so as to fall into another filter can be seen even if the aircraft echo is substantially less than the  weat her echo.  A digital clutter map is generated which establishes the thresholds for the zero-velocity  cells. 
 92-95 Doppler-tolerant waveform, 427 Doppler tracking, 182 Double-curvature reflector. 259 Doubledelaylinecanceler, 109 Double-null diffcn:ncc pattcrn, 175 Double-threshold detector, 388 DPCA,143-144 Dual-mode ferritephaseshifter,295296 Dueling, 450-456 Duplexers, 359366 anddiodeburnout, 350 Dutycycle,52 Dynamic programming, 332 Dynamic range,352 andlow-noise receivers, 352 Eaglescanner, 298 ECCM,542,547-553 Effective aperture, antena,226-227 Effective bandwidth, 404-405 Effective earth'sradius,449 Effective noisetemperature, 345 Efficiency: aperture, 228-232. INDEX 575  Efficiency :  klystron. 
 PULSE CANCELER  AFTER 4 - (ALL AND 7 7 3HRADER  Ú )%%%  AND ( 2 7ARD AND 7 7 3HRADER Ú )%%%        
 The individual intermediate cavities of  a multicavity klystron are each replaced by a cluster of two or three artificially loaded  low-Q cavities with Qs of one half to one third of the single cavity they replace.21  Figure 10.4 compares schematically the basic difference between the conventional  stagger-tuned klystron and the clustered-cavity klystron. It has been said for a given FIGURE 10. 3 Basic structure of several types of linear  beam tubes: ( a) klystron, ( b) coupled-cavity TWT, ( c) extended  interaction klystron, and ( d) Twystron ( after A. 
 Air Force reports on Hughes Air Defense Radar, Flight Int., Dec. 4, 1982. 30. 
 AF-6, pp. 380--384, October, 1958.  100. 
 In our work, the simulation is iteratively performed on the point array target as is shown in Figure 10. For each group of scintillation parameters, the iterations are performed for 500 times and the statistical results are shown in Figure 14. As is discussed in Section 3, the signal decorrelation is not sensitive to the outer scale. 
 19.8 Inverse-receiver block diagram. The narrow banding is placed very early in the re- ceiver, inverting the bandwidth' 'funnel'' of the conventional receiver and excluding interference from subsequent stages of the seeker.FRONT ANTENNA FRONTIFBALANCEDMIXERDOPPLERAMPLIFIER(4MHz)SPEEDGATE1ST IFSPEEDGATE20 IFBOHESIGHTERROR LOCALOSCILLATORAFCSINGLE-SIDEBANDFILTERCONVERSIONOSCILLATOR AFC REAR ANTENNAREARIF4-MHzOSCILLATORSPEEDGATELOCALOSCILLATOR FRONT ANTENNA PREAMPLIFIER NARROWBANDFILTERIFPOSTAMPLIFIERANGLE ERROR 2d IFAMPLIFIER DOPPLERTRACKING LOOPCONVERSION OSCILLATOR DOPPLERERROR MICROWAVELOCAL OSCILLATORFREQUENCY CONTROL . are rejected very early in the signal path, thus reducing dynamic-range require- ments and avoiding most possible sources of distortion. 
 This carrier may be defined by the initial value of the first integrator. The desired initial phase of the waveform is the initial value of the second integrator or else may be added to the second-integrator output. Figure 10.4 illustrates two digital approaches to providing the matched filter for a pulse compression waveform. 
 The range marks are at 10-nmi intervals.  The picture on the left is the normal video display, showing mainly the fixed-target  returns. The picture on the right shows the effectiveness of the MTI clutter rejection. 
 CIENTS DONT REQUIRE MULTIPLIERS 4HE FREQUENCY RESPONSES SYMMETRY ABOUT  OF THE SAMPLING RATE CAUSES THE EVEN 
 TALLY POLARIZED SLOTS PER STICK 4HE ARRAY IS FED FROM A SOLID 
 J.: Additional Characteristics of Synthetic Aperture Sonar Systems and a Further Comparison with Non-Synthetic Aperture Sonar Systems, /. Acoust. Soc. 
 NOISE RATIO OR RANGE RESOLUTION 3TRETCH PULSE COMPRESSION IS USED FOR A SINGLE TARGET OR FOR MULTIPLE TARGETS THAT ARE LOCATED WITHIN A RELATIVELY SMALL RANGE WINDOW CENTERED AT A SELECTED RANGE  &IGURE  SHOWS A BLOCK DIAGRAM OF A STRETCH PULSE COMPRESSION SYSTEM 4HE  ,&- WAVEFORM HAS A SWEPT BANDWIDTH  "  PULSEWIDTH  4  AND ,&- SLOPE  A 4HE REFER 
 The received signal was digitized  into 2540 complex numbers (4 bits I, 4 bits Q). A radar look was taken every 0.3 seconds  and stored in a RAM memory buffer. To keep up with this data rate, recording alternated  between two onboard tape recorders. 
 Three regions of bistatic RCS are of interest: pseudo-monostatic, bistatic, and forward scatter (sometimes called near-forward scatter"). Each region is defined by the bistatic angle. The extent of each region is set primarily by physical char- acteristics of the target. 
 Figure 12.26 shows a few common types of flared horn feeds.   FIGURE 12. 25 Some typical reflector antenna configurations ch12.indd   25 12/17/07   2:31:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Energy scattered out ofthe directed beam must, ofcourse, becounted aslost. 0,010.5 1 5 10 Wavelength incm FIG.2.17.—Solid curves show attenuation inrainofintensity (a),0.25mm/hr (drizzle); (b),1mm/hr (light rain); (c),4mm/hr(moderate ra,n); (d),16mm/hr (heavy rain). Dashed curves show attenuation infogorcloud: (e),0.032g/m’(visibility about2oooft); (j),0.32glm~(visibility about400ft);(u),2.3g/mi(visibility about100ft). 
 (17.2). Main-Beam Clutter Filtering. In a pulse doppler radar utilizing digital signal processing, main-beam clutter is rejected by either a combination of a delay- line clutter canceler followed by a doppler filter bank or by a filter bank with low filter sidelobes. 
 TIETH CENTURY   !NTENNA CHARACTERISTICS ARE DETERMINED BY THE GEOMETRIC POSITION OF  THE RADIATORS AND THE AMPLITUDE AND PHASE OF THEIR EXCITATION !S RADARS PROGRESSED TO SHORTER WAVELENGTHS  ARRAYS WERE DISPLACED BY SIMPLER ANTENNAS SUCH AS PARABOLIC REFLECTORS &OR MODERN RADAR APPLICATIONS  THE ADVENT OF ELECTRONICALLY CONTROLLED PHASE SHIFTERS  SWITCHES  AND TRANSMITRECEIVE MODULES HAS ONCE MORE DIRECTED ATTENTION TO ARRAY ANTENNAS 4HE APERTURE EXCITATION MAY NOW BE MODULATED BY CONTROLLING THE PHASE OF THE INDIVIDUAL ELEMENTS TO GIVE BEAMS THAT ARE SCANNED ELECTRONICALLY 4HE DRAMATIC ADVANTAGE OF ELECTRONICALLY STEERED PHASED ARRAYS AS COMPARED TO REFLECTORS IS PROVIDED BY THE TIME REQUIRED TO STEER BEAMS AND THE FLEXIBILITY IN STEERING 7HILE PRIOR RADARS TOOK SECONDS TO STEER TO A NEW LOCATION  PHASED ARRAYS TAKE MICROSECONDS )N ADDITION  THE NEW LOCATION CAN BE ANYWHERE IN A HEMISPHERE 4HIS CHAPTER WILL BE DEVOTED TO ARRAYS OF THIS TYPE -ULTIFUNCTION 2ADAR  4HE CAPABILITY OF RAPIDLY AND ACCURATELY SWITCHING BEAMS  PERMITS MULTIPLE RADAR FUNCTIONS TO BE PERFORMED  INTERLACED IN TIME !N ELECTRONICALLY STEERED ARRAY RADAR MAY TRACK A GREAT MULTIPLICITY OF TARGETS  ILLUMINATE A NUMBER OF TARGETS WITH 2& ENERGY AND GUIDE MISSILES TOWARD THEM  AND PERFORM COMPLETE HEMI 
 The gas gap is placed in the  feeder system at such a point that the short-circuit of  the gap transforms the receiver side of the feeder into a  quarter-wave line, so this time the passage to the  receiver is blocked by conditions of infinite impedance,  and all the energy passes from the transmitter to the  aerial. This switch-over takes place over 500 times a  second, and if the gas gap of H2S were to break down or  fail to work on any one pulse the receiver would be —  burned out. Precautions are taken, therefore, as in all  similar centimetric aerial T-R switching devices, by  inserting impedance transformations to give additional  protection. 
 OD coaxial line, but animmediate transition ismade tostandard waveguide l+by3in.with 0.080-in. wall. Since both the coaxial line and waveguide areoperating notvery farfrom thevoltage-breakdown point, aspecially tapered “door- knob” transition isnecessary. 
 Nobli t18 ) ch09.indd   15 12/15/07   6:07:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 
 It becomes expensive atwider bandwidths, although animprovement in tube performance would raise this figure proportionately. The inductance Listuned toresonate attheintermediate frequency with the combined output and input capacity plus stray capacity to ground due tosockets and wiring. Itisplaced inthe grid circuit to provide alow-resistance path toground. 
 LOCATED IE  WHEN  ,    )T IS DEFINED AS THE BISTATIC RADARS  BENCHMARK RANGE   3INCE THIS BENCHMARK IS GEOMETRY 
 One of the harmonics offm is selected (in this case the third) by a filter centered at  the harmonic. The filter bandwidth is wide enough to pass both doppler-frequency sidebands.  The filter output is mixed with the (third) harmonic of.fm. 
 linear aperture oftheenclosed portion oftheantenna toproduce thebeam 0.55° inazimuth by3°inelevation. Terminating inthis aperture isalong “horn,” aparallel-plate region ofcopper-coated plywood, folded asinFig. 9.26. 
    
 Onthe other hand, ifexcitation bylight could beused theexcitation density could be kept very low because thescreen would beexcited throughout. Thk is accomplished bythe simple but exceedingly clever expedient ofcover- ingthepersistent screen with asecond layer ofablue-emitting phosphor which undergoes primary excitation bythe electrons. The blue light from this layer inturn excites the persistent screen. 
 The baseline single-look SAR azimuth resolution  is proportional to one over the doppler bandwidth generated by the azimuth beam - width of the side-looking antenna. The corresponding length of the synthetic aperture  is equivalent to the along-track spread of the antenna pattern, which, of course, is  proportional to range. Let this be the canonical case. 
 BASED RADARS AS WELL AS AIRBORNE RADAR ! FUNCTIONAL BLOCK DIAGRAM OF AN AIRBORNE RADAR EMPLOYING 4!##! 2 IS SHOWN IN  &IGURE  4HE CLUTTER ERROR SIGNAL IS OBTAINED BY MEASURING THE PULSE 
 T(x,y,z ) is the target coordinate system, in which axis yis coincident with axis y’, and axes xand yrepresent the azimuth direction and range direction of ISAR, respectively, and distance between origins of the two coordinate systems is R0(R0<4 D2/λ,Dis the maximum size of the target and λis the wavelength of the incident wave). The target is moving at a constant speed in plane ( x,y) at an angular velocity ω, and plane ( x’,y’) is parallel to plane ( x,y). Assuming that coordinate of any point Pon the target is ( x,y,z ), and the coordinate in the cylindrical coordinate system is ( r0,θ0,z). 
 I. Skolnik (ed.),  McGraw-Hill Book Co.. N.Y.. 
 2013 ,10, 1552–1556. [ CrossRef ] 36. Leng, X.; Ji, K.; Zhou, S.; Xing, X.; Zou, H. 
 58. Worley, R.: Optimum Thresholds for Binary Integration, IEEE Trans., vol. IT-14, pp. 
 The squint angle of the forward-looking beam is 20◦, and the scenario image processed by the above imaging algorithm is shown in Figure 11a, the position of the center point target is (1025, 2050), and the positions of the other four points are (1025 ±135, 2050 ±120). The azimuth sampling rate is 17. Sensors 2019 ,19, 1701 1.35 times of the azimuth bandwidth, so the distance between the center point target and the rest of the point target in the azimuth direction is 135/1.35 ×0.3 = 30 m, which is consistent with the scenario layout; The range sampling rate is 1.2 times of the bandwidth, and the distance between the center point target and the rest of the point target in the range direction is 120/1.2 ×0.3 = 30 m, which is consistent with the scenario layout. 
 W.: Moving Target Indication Radar, IEEE 74 Record NEREM, Pt 4, pp. 18-26,  Oct. 28-31, 1974, IEEE Catalog no. 
 SHELF  COMMERCIAL HARDWARE .OTABLE EXAMPLES ARE THE .!4/ AIR DEFENSE TRIALS     AND THE 5NIVERSITY OF 7ASHINGTONS  -ANASTASH 2IDGE 2ADAR  MEASURING IONOSPHERE  TURBULENCE BOTH PASSIVE BISTATIC RADARS EXPLOITING &- BROADCAST TRANSMITTERS  THE ($46 
 OVER OF THE WEAPON IN FLIGHT  4IME SYNCHRONIZED WITH A RADAR TRANSMISSION ON A DIFFERENT SET OF BEAMS ANDOR FRE 
 TIME WIND MEASUREMENT IN EXTRATROPICAL CYCLONES BY MEANS OF DOPPLER RADAR v   * !PPL -ETEOROL  VOL   PP n    * 2TTGER AND - & ,ARSEN  h5(&6(& RADAR TECHNIQUES FOR ATMOSPHERIC RESEARCH AND WIND  PROFILER APPLICATIONS v #HAPTER  IN  2ADAR IN -ETEOROLOGY  !TLAS ED  "OSTON !-3      PP n   6 #HANDRASEKAR  2 -ENEGHINI  AND ) :AWADZKI  h'LOBAL AND LOCAL PRECIPITATION MEASUREMENTS  BY RADAR v #HAPTER  IN  2ADAR IN !TMOSPHERIC 3CIENCE ! COLLECTION OF ESSAYS IN HONOR OF $AVID  !TLAS  2 7AKIMOTO AND 2 3RIVASTAVA EDS   -ETEOROLOGICAL -ONOGRAPH  VOL   "OSTON !-3    PP n  * 7URMAN  * 3TRAKA  % 2ASMUSSEN  - 2ANDALL  AND ! :AHRAI  h$ESIGN AND DEPLOYMENT OF  A PORTABLE  PENCIL 
 The use of frequency diversity, as described previously for reducing glint, can also reduce  the multipath tracking error. As seen in Fig. 5.16, the angle errors due to multipath at low  angle are cyclical. 
 RADIUS CONCEPT  REPLACES THE %ARTHS TRUE RADIUS WITH A LARGER RADIUS SUCH THAT THE RELATIVE  CURVATURE BETWEEN THE RAY AND THE  %ARTHS SURFACE IS MAINTAINED  AND THE RAY BECOMES  A STRAIGHT LINE 4HE EFFECTIVE 
   PP n  *ULY   % * 7ILKINSON AND ! * !PPLEBAUM  h#ASSEGRAIN SYSTEMS v  )2% 4RANS  VOL !0 
 INTERVAL DELAY 4HE LOCATION OF THE ONE NONZERO  COEFFICIENT IN THE REAL PART  H )N  OF THE &IGURE  IMPULSE RESPONSE CORRESPONDS TO AN  ODD 
 STATE AND VACUUM ELECTRONICS TECHNOLOGIES CAN BE WIDE  THERE STILL EXIST RELEVANT TRADES INVOLVING COST  MAINTAINABILITY  AND RELIABILITY  AND THIS DESIGN TRADESPACE CAN BE VERY COMPLICATED 3OME POINT TO THE CONTINUED MATURATION OF VACUUM ELECTRONICS  AND SUGGEST THAT BOTH  VACUUM TUBES AND SOLID 
 The main pulse consists of microbursts almost with the same form. In each frequency channel three monochromatic microbursts can be revealed, which can be described as Gaussian pulses with diﬀerent amplitudes. 2. 
 The use of subarrays usually simplifies the problem of the beam-steering computer.  Instead of requiring a coninland for each of the elements of the array, the subarray steering  requires only p + q pliase shifter commands per pointing angle, where p is the number of  elernents in the subarray and q is the number of subarrays in the array. However, with q  identical subarrays of p elements each, the tolerance on the individual phase shifters must  usually be ketter than with a similar conventional array of pq elements since with subarrays  the errors across the entire aperture are no longer independent. 
 Tait, Introduction to Radar Target Recognition , Bodmin, Cornwall, UK: IEE, 2005,   pp. 105–217, 317–347. 73. 
 Law £,iforcement. In addition to the wide use of radar to measure the speed of automobile  traffic by highway police, radar has also been employed as a means for the detection of  intruders.  Military. 
  TO  
 BUILT EQUIPMENT FOR EACH OF THESE APPLICATIONS HAS BEEN BEING DEVELOPED  AND  THE USER NOW HAS A BETTER CHOICE OF EQUIPMENT AND TECHNIQUES '02 HAS ADVANCED RAPIDLY AS A RESULT OF A VARIETY OF APPLICATIONS  BUT AS THE REQUIRE 
 Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 5.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 An example comparison of HPRF and MPRF as a function of altitude for a given  maximum transmitter power, power-aperture product, and typical antenna and radome  integrated sidelobe ratio is shown in Figure 5.21. At high altitude and nose-on, there is  more than an 11 dB difference caused by blind zones, straddle, folded clutter, process - ing, and thresholding losses.9,11,28 RGHPRF Selection Algorithms. 
 TRACKING CIRCUITS ! REPEATER JAMMER SENDS BACK AN AMPLIFIED VERSION OF THE SIGNAL RECEIVED FROM THE RADAR 4HE DECEPTION SIGNAL  BEING STRONGER THAN THE RADARS RETURN SIGNAL  CAPTURES THE RANGE 
 J. Geophys. Res. 
 129 - 134, Stuttgart, Sept. 13 ,1991  − K. Schuler, M. 
 Guinard, J. T. Ransone, Jr., and J. 
 182. L. Liang and R. 
 antenna. 224-226  Gaseous discharge pliase shifter, 297  Gaussian probability density function, 22  Geodesic dome. 265  Glirrt, 168-172  Grating lobes, 281, 283, 300, 332  Grazing angle, 473  Grid-controlled tubes, 2 13  Ground-wave OTH radar, 536  Half-wave wall radome, 267  Hard-tube modulator, 215-2 16  Height finder radar, 541 -546  Helical scan, 177, 545  Hemispherical coverage arrays, 328-329  HF OTH radar, 529-536  High-range-resolution monopulse, 18 1 - 182,  High-range-resolution radar, 434-435  Hologram, 523-526  Home on jam, 549  Huggins phase shifter, 303-305  Hybrid-coupled phase shifter, 289  IAGC, 488  Ice:  on antennas, 240  on radomes, 269  sea, 48 1-482  Ice spheres, scattering from, 502  Ideal observer, 380  IF cancellation, MTI, 126  Image frequency, of mixer, 347  Image-recovery mixer, 349  Improvement factor, MTI:  antenna scanning, 134- 136  antenna sidelobes, 145  clutter fluctuations, 131-134  defined, 11 1, 129  equipment instability, 130-13 1  limiting. 
 The distance, or range, to the target is determined by measuring the  time TR taken by the pulse to travel to the target and return. Since electromagnetic energy  propagates at the speed of light c = 3 x 10' m/s, the range R is  The factor 2 appears in the denominator because of the two-way propagation of radar. With  the range in kilometers or nautical miles, and TR in microseconds, Eq. 
 Wilson, “Radar  refractivity retrieval: Validation and application to short-term forecasting,” J. Appl. Meteoro. 
 Less average power output is feasible than for tubes with conventional tuners, since cooling the rotary tuner is more difficult. Precise band-edge tuning is not assured; since the entire tuning range is always covered on each cycle and since system operation outside the assigned band is usually not permissible, tol- erances on tuning range must be absorbed within the band. When used for MTI (with the tuner stopped), stability is less good than with other tuners. 
 ,Ê   Ê 
 High-Power Amplifier Design. In the corporate-combined system, high power levels are generated at a single point by combining the outputs of many low-power amplifiers. The amplifier module is usually partitioned such that the required electrical performance is achieved while the constraints imposed by the mechanical, cooling, maintenance, repair, and reliability disciplines are simultaneously achieved. 
 TO 
 Monog ., 5047, February 1965.  6. A. 
 234 INTRODUCTION TO RADAR SYSTEMS  -5 ,;. -·;;;  C:  -10 Q) -C:  C  0  -15 0  -0  0  L  -20 Q)  > ·..=  .!?  Q)  L -25 N ~,'v •• -30 '-5'  -35  -10 -8 -6 -4 -2 0 2 4 6 8 10  ( = 21r (r0/>.) sin cp  Figure 7.4 Radiation pattern for a uniformly illuminated circular aperture.  the blocking caused by the feed and its supports in reflector-type antennas. 
 PROCESSOR COMBINATION  TO FORM THE SYNTHETIC APERTURE AND THE RESULTING ENHANCED RESOLUTION 3PECKLE CAN BE REDUCED ONLY THROUGH SUPPLEMENTAL INCOHERENT PROCESSING  MULTI 
 W., and R. C. Hansen: Scanning Surface Wave Antennas: Oblique Surface Waves over  a Corrugated Conductor, IRE Trans., vol. 
 12.4 REFLECTOR FEEDS Whereas phased array antennas are frequently chosen for radar system designs, reflec - tor antennas were once the dominant antenna design choice for medium- to high-gain  radar apertures. Obviously, the cost of a single feed horn and metal reflector is much less  than the same size array with many individual elements and associated phase shifters,  amplifiers, receivers, etc. Consequently, many radars currently in the field use reflec - tor antennas. 
 An antenna beam shape of (sin U)IU9 terminated at the first nulls, was assumed. The shape of these curves, except very near the blind speeds, is essentially independent of the number of hits per beamwidth or the assumed beam shape. The ordinate, labeled "response," represents the single-pulse signal-to-noise response of the MTI receiver relative to the signal-to-noise response of a normal linear receiver for the same target. 
 CIALLY TORNADOES AS SHOWN IN PHOTO 0HOTO COURTESY OF 5NIVERSITY #ORPORATION FOR !TMOSPHERIC 2ESEARCH Ú    "OULDER  #/  . 
 The dielectric constant and permeability were produced byahigh concentration ofspheroidal metal particles (carbonyl iron). The concentration ofmetal was80 per 100 10 z~ k $ 1J= (i 0.1 051015202530354045 505560 Anglewithnormaltoplateindegrees F]~.3.5.—ElTect ofabsorbing material onenergy returned from aflatplate atvarious zm,glesof incidence. Curves: diffraction pattern ofametal plate, electric vector ofradia- tionnormal toPlane ofincidehce. 
 7.6 50percent ofthetotal plots obtained were passed on. However, 84per cent ofthe tracks were reported, the difference being due tosingle-plot tracks which were not reported. The average number ofplots pertrack was 6.2and theaverage track duration 9.5min. 
 In one airborne monopulse radar  antenna23 using the polarization twisting technique, good performance was obtained over a 12  percent bandwidth. The subreflector was supported by a transparent (dielectric) cone, with  resistive-card absorbers embedded in the ·support cone and oriented so as to reduce the  I .  cross-polarized wide-angle radiation by more t'1an 20 dB. 
 The results indicate a good accordance to the standard focusing of obtained images with respect to the ofﬁcially distributed ones. Also, the algorithm can reveal interesting and convenient in several application ﬁelds such as local zones monitoring by SAR systems carried by small lightweight and low-cost aerial unmanned vehicles. Modern hardware technology permits to reduce the size and weight of SAR systems into small and cheap ﬂying platforms that can be conveniently used with low-cost platforms and ﬂying drones. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.88  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 a bird flock (in a single radar resolution cell). 
 Comments on the table .6 The International Telecommunications Union (ITU)  assigns specific portions of the electromagnetic spectrum for radiolocation (radar)  use as shown in the third column, which applies to ITU Region 2 that includes North   and South America. Slight differences occur in the other two ITU Regions. Thus an   L-band radar can only operate within the frequency range from 1215 MHz to 1400 MHz,  and even within this range, there may be restrictions. 
 -(Z REFERENCE OSCILLATOR  FROM WHICH IS DERIVED A   -(Z )& CENTER FREQUENCY ON TRANSMIT AND RECEIVE  AND A COMPLEX SAMPLE RATE OF  -(Z ! RULE OF THUMB IS THAT THE CLOCK USED TO PRODUCE THE PULSE REPETITION INTERVAL 02)  NEEDS TO BE A COMMON DENOMINATOR OF THE )& CENTER FREQUENCIES ON TRANSMIT AND RECEIVE AND THE COMPLEX SAMPLE FREQUENCY IN ORDER TO ASSURE PULSE 
 ITY n 0ERHAPS HALF THE COST  AND COMPLEXITY OF AN !%3!  IS IN THE 42 CHANNELS 4HAT  SAID  HOWEVER  THE FEED NETWORK  BEAM STEERING CONTROLLER "3#   !%3! POWER SUPPLY  AND COOLING SUBSYSTEM AIR OR LIQUID  ARE EQUALLY IMPORTANT  &)'52%  3TRIKE FIGHTER PULSE DOPPLER GEOMETRY  . 
 Atargetatshortrangewillgenerally resultinastrongsignalatlowfrequency, whileone atlongrangewillresultinaweaksignalathighfrequency. Therefore thefrequency character­ isticofthelow-frequency amplifier intheFM-CW radarmaybeshapedtoprovideattenua­ tionatthelowfrequencies corresponding toshortrangesandlargeechosignals. Less attcntuation isapplicdtothehigherfrequencies, wheretheechosignalsareweaker. 
 !ROUND 4RACKING  4O EXTEND UNAMBIGUOUS RANGE BY REDUCING THE  02& INCREASES THE ACQUISITION TIME AND REDUCES THE DATA RATE !  SOLUTION TO THIS PROB 
 In addition, the receiver may or may not use a range gate. If only the central-line power of the PD spectrum is used (no range gate), the resulting loss must be ac- cepted. Use of a range gate matched to the pulse avoids this loss. 
 L., and J. J. Fleming: The Navy Space Surveillance System, Proc. 
 WALLED TUBE   PARALLEL TO  BUT ISOLATED FROM  THE OTHER BEAMLETS 4HEY ARE ALLOWED TO INTERACT ONLY OVER THE SMALL AXIAL EXTENT OF THE CAVITY GAP !FTER PASSING BY THE CAVITY GAP  THE BEAMLETS REENTER THEIR INDIVIDUAL DRIFT CHANNELS AND PROPAGATE IN ISOLATION FROM ONE ANOTHER 3UCH KLYSTRONS ARE CALLED  MULTIPLE 
 48-52, Atlanta, March 1984. 54. Bistatic Radars Hold Promise for Future Systems, Microwave Syst. 
 M., and C. E. Antoniak: A Practical Distribution-Free Detection Procedure for Multiple-  Range-Bin Radars, I EEE Trans., vol. 
 Strauch, and G. M. Heymsfield: Simulation of Wind Profilers in Disturbed Conditions, Preprints, 23d Conf. 
 m  I). = receiver-to-target distance. m  L,,{t) = propagation loss over transmitter-to-target path  LP(r) = propagation loss over receiver-to-target path OTIIER RADAR TOPl('S 557  (14.36)  Equations (14.35) and (14.36) represent but one of the several forms in which the radar  equation may be written. 
 LOOKING VIEWING GEOMETRY 4HE INSTRUMENT WAS BASED ON SYNTHETIC APERTURE RADAR 3!2  PRINCIPLES 4HE DATA WERE RECORDED DIRECTLY ONTO  
 A Vac-Ion pump (trademark of Varian Associ- ates) can be used to maintain a good vacuum, even during storage, and to indicate the quality of the vacuum. Most crossed-field tubes don't require ion pumps be- cause they will pump themselves down when operated.ELECTRONBEAM FROMCATHODEAT-53 kV HV INSULATORS . TABLE 4.1 High-Power Pulsed Amplifiers Compared for Same Frequency and Peak and Average Power Output *Distributed emission, reentrant, circular. 
 The skins might typically have a dielectric constant of about 4, and the core might  have a value of about 1.2. The skins are thin compared to a wavelength. The core might be a  honeycomb or fluted construction. 
 12.2.4  Receiver and Signal Processor Considerations   Today most Radar receivers use digital signal processing. A generic block diagram of  such a  Radar receiver is shown in Figure 12.24.     Figure 12.24  Digital implementation of non -linear chirp pulse compression. 
 Consider a pulse radar viewing the target and the clutter at low grazing angles. If single-pulse detection is assumed, the signal-to-clutter ratio is s _ a C = a°/?6,(cT/2) sec <j> (UO) or R = Z max (S/C)mincj\(cT/2) sec 4> where R = range to clutter patch 0fo = azimuth beamwidth c = velocity of propagation T = pulse width <|> = grazing angle The clutter patch is assumed to be determined in azimuth by the width of the antenna beam and in the range coordinate by the pulse width. The ratio SIC takes a role similar to the ratio ElN0 for thermal noise. 
 Compared to the other conventional autofocus methods, the metric-based methods can work well without prominent points but deal with an already focused image. The defocused image can be considered as the perfect focused image convoluted with the point spread function (PSF) caused by the phase error. Only recently and with the advent of lightweight and 88. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 Hence, to achieve L = 10 km at 1200 km range when the frequency is 15 MHz, and  thus a resolution cell not too eccentric in shape, requires an array aperture of about  2400 m. Feeding arrays of this size can require hundreds of kilometers of cables or, in  some systems, fiber optics, and raises challenging problems in array calibration. 
 For the full aperture approach, they can be divided into two kinds. The ﬁrst one assumes that the scattering during one subaperture is isotropic and reconstructs an imaging model with all subapertures included [ 6–8]. The subaperture images are recovered jointly. 
 Good ground- moving target rejection. Measures  radial velocity.Limited low radial velocity target  detection. Range eclipsing. 
 Ground terminal common toallcircuits.. 576 PRIME POWER SUPPLIES FORRADAR [SEC. 14.6 alternator resistancefield must bekept inproper relation tothe normal range of ofthe carbon pile inorder toobtain good speed regulation. 
 Headrick, J. F. Thomason, D. 
 PERS OF ANOTHER PLANET 4HEY IMAGED THE AREA FROM THE NORTH POLE DOWN TO ABOUT  n.  LATITUDE OVER  MONTHS OF OPERATIONS 4HEIR RADARS HAD TWO MODES  IMAGING AND ALTIM 
 PURPOSE PROCESSORS THAT ARE CONNECTED VIA HIGH 
 PLANE POLE 
 Cooper, D. C., and J. W. 
 Similarly, the double-threshold detector hassomeadvantage overtheusualintegrator whenthebackground interrerence isnotreceiver noisebutisnongaussian, asissomeseaclutterandlandclutter. 10,000.---rlr------,,-------,-----,---:cJ l{) r0-0 -N8 -::, (l)~.cu'"00o L1,000::-- §t -<l: oneu ~ :::Jr 0. '0 Leu100D E :::J C 0 0 r::: 10 Figure10.8Optimum numberofpulsesmOpl(outofa f '__--'--__..L..._--..l.__-l-_~ maximum ofn)forabinarymovingwindowdetector. 
 192-253, December, 1955, and vol. 4,  pp. 86-1 19, June, 1956:. 
 S. Applegate: Radar Backscatter from Land, Sea. Rain, and Snow at  Millimeter Wavelengths. 
 Elsewhere, the isodops are  nonstationary. In these nonstationary regions, the quality of bistatic SAR imagery is  limited and moving target indication (MTI) performance is degraded when using stan - dard monostatic radar processing techniques. FIGURE 23.7  Bistatic isodoppler contours for two dimensions and a flat  earth ( Courtesy Lee R. 
 It lies within the sidelobe clutter region of the pulse doppler spectrum. Because it can be much larger than diffuse sidelobe clutter and has a rela- tively narrow spectral width, altitude-line clutter is often removed by either a special CFAR which prevents detection of the altitude line or by a tracker- blanker which removes these reports from the final output. In the case of the tracker-blanker, a closed-loop tracker is used to position range and velocity gates around the altitude return and blank the affected range-doppler region.FILTER NUMBER 256-POINTFFTGAUSSIAN CLUTTER SPECTRUM 90-dB DOLPH-CHEBYSHEVWEIGHTINGDC= FILTER NO. 
 be minimized by choosing the diameter of the subreflector equal to that of the feed.26 This occurs when D8 - \/2fm\/k (6.23) where k is the ratio of the feed-aperture diameter to its effective blocking diam- eter. Ordinarily k is slightly less than 1. If the system allows, blocking can be reduced significantly by using a polarization-twist reflector and a subreflector made of parallel wires.3-26 The subreflector is transparent to the secondary beam with its twisted polarization. 
 If two or more targets are present, the residue will contain signal from the remaining targets and should be large. The results of resolving two targets with S/N = 20 dB are shown in Fig. 8.23. 
 # (* 
 K  . supplanted solar and stellar observations because of its  convenience, but not because of its greater accuracy.  By astronomical methods a really good observer can  determine the position of a ship to within a mile or two,  and of an aircraft to within eight miles, if circumstances  are favourable. 
 Air or water cooling might be needed.  The ferrite material may be biased, as for example a latching-ferrite circulator, to permit  the handling of higher power. 45 Since the latching-ferrite receiver protector is undamaged by  high power when in either state, protection from nearby transmitters can be had by inserting a  passive TR -li111iter following the ferrite. 
 Thus tliis warmer, drier air lies above the  coolct . 111oist :ti1 to oducc a tc11llwt.nt1l1.c i~ivc~.sio~i; i.c.. ;\I\ iticrc;~se .ill tc~i~pc~,nti~ro wit11  tleiglit. 
 Indeed itwould besurprising ifany one criterion, appro- priate toallofthevarious methods offinal detection that can beused, could befound. This need notdiscourage usasitturns outthat allsuch criteria lead tosimilar results, and that moreover theminimum isfairly flat. Some results obtained bythegroup headed byJ.L.Lawson intheir investigation ofsignal discernibility yaredisplayed inFig. 
 Jao and W. B. Goggins, “Efficient, closed-form computation of airborne pulse doppler clut - ter,” in Proceedings of the 1985 IEEE International Radar Conference,  Washington, DC, 1985,  pp. 
 TO 
 POWER RADARS  BECAUSE   EACH PULSE CONTAINS THE FULL BANDWIDTH  THEREBY ENABLING THE FULL BANDWIDTH TO BE TRANSMITTED AND RECEIVED MUCH MORE QUICKLY THAN WITH STEP 
 - )N THE ULTRAWIDEBAND CASE  THE RADAR ANTENNAS ARE CONSIDERED IN TERMS OF THEIR TRANSFER FUNCTION RATHER THAN THEIR GAINS OR EFFECTIVE APERTURES )N MANY CASES  A SEPARATE TRANSMIT AND RECEIVE ANTENNA IS USED HENCE THEIR TRANSFER FUNCTIONS MAY NOT BE IDENTICAL 4HE TYPE OF ANTENNA THAT IS USED WITH ULTRAWIDEBAND RADAR HAS AN IMPORTANT ROLE IN DEFINING THE PERFORMANCE OF THE RADAR. 
 A bar refers to a line of beam positions at a constant elevation. In search, a multi - bar raster  scans the beam over an assigned area or volume to create a frame . A frame  may have multiple bars. 
 J. Guerci, Space-Time Adaptive Processing for Radar , Norwood, MA: Artech House, 2003. 47. 
 -OSKOWITZ  TYPE  REPRESENTING FULLY DEVELOPED SEAS  AFTER  7  *  0IERSON  AND   , -OSKOWITZ Ú !MERICAN 'EOPHYSICAL 5NION  . £x°È  2!$!2 (!.$"//+  4HE RMS WAVEHEIGHT CONTAINS CONTRIBUTIONS FROM ALL THE WAVES ON THE SURFACE  BUT  VERY OFTEN IT IS THE PEAK 
 MUTH RESOLUTION  SINCE IT IS MEASURED ALONG A LINE OBTAINED BY HOLDING RANGE CONSTANT AND VARYING THE AZIMUTH AS MEASURED FROM THE PHYSICAL ANTENNA  OF THE ,/3 )F AND ONLY IF  THE ,/3 REMAINS PERPENDICULAR TO THE DIRECTION OF FLIGHT  RANGE RESOLUTION IS SOMETIMES CALLED  CROSS 
 simultaneously from a single aperture. In principle, an N-element array can generate N  independent beams. Multiple beams allow parallel operation and a higher data rate than can  be achieved from a single beam. 
 The optimal value of Pn, the prob- ability of exceeding J1 when only noise is present, was calculated by Dillard18 and is shown in Fig. 8.8. The corresponding threshold T1 is T1 = a(-2 In P*/2 (8.15) A comparison of the optimal (best value of M) binary integrator with various other procedures is given in Figs. 
 Given the constraint of the number of pulses on target, one must decide how many CPIs should occur during the time on target and how many pulses per CPI. The compromise is usually difficult. One wishes to use more pulses per CPI to enable the use of better filters, but one also wishes to have as many CPIs as possible. 
 CALLED  O  MODE  OF THE MICROWAVE CIRCUIT  AND  THE TUBE CAN GENERATE OSCILLATIONS 4HESE OSCILLATIONS AT THE LEADING AND TRAILING EDGES OF THE 2& OUTPUT PULSE HAVE A CHARACTERISTIC APPEARANCE ON A POWER 
 Also, too much gate periphery  may increase the chip area such that cost of the component becomes unattractive.   (2) Losses in the output circuit of the final stage can significantly reduce power output  and efficiency. Off-chip matching may be necessary to maximize power output for a  given design. 
 L PLN    ,EAKAGE,OSS   &)'52%  #OMMON REFLECTOR SURFACE MATERIALS FOR REDUCED WIND RESISTANCE  A  TUBING  B  EXPANDED  METAL  C  RECTANGULAR  D  DOUBLE LAYER  AND E  SCREEN. £Ó°£Ó  2!$!2 (!.$"//+  4HIS NOMOGRAPH IS FREQUENTLY USED FOR THE SIMPLE CONFIGURATIONS IN &IGURE  A &OR  OTHER CONFIGURATIONS AND THREAD FORMS  THE SAME EQUATION CAN BE USED BY COMPUTING  AN EQUIVALENT RADIUS BY MATCHING THE CROSS SECTIONAL AREAS /NE SIGNIFICANT SOURCE OF RADIATION IN THE BACK HEMISPHERE IS LEAKAGE THROUGH  THE REFLECTOR 4HIS RADIATION LEVEL IS DETERMINED FROM THE DIFFERENCE BETWEEN PRIMARY FEED HORN  AND SECONDARY REFLECTOR  GAINS AND THE LEAKAGE LOSS  RADIATION THROUGH THE MESH 4HERE ARE TWO CONSIDERATIONS REGARDING THE REFLECTOR SURFACE LEAKAGE 4HE LEAKAGE  LOSS AFFECTS THE REFLECTOR GAIN DIRECTLY 4HE RADIATION LEVEL I N THE BACK HEMISPHERE IS A  FUNCTION OF THE FEED GAIN  REDUCED BY THE TRANSMISSION LOSS THROUGH THE REFLECTOR 4HUS  THE REFLECTOR DESIGNER MUST CONSIDER BOTH THE LEAKAGE LOSS AND THE TRANSMISSION LOSS &IGURE   4HERE ARE  HOWEVER  ADDITIONAL BACKLOBES THAT ARE DISTINCT FROM THE BACK RADIATION DUE  TO SURFACE LEAKAGE 4HESE ADDITIONAL LOBES ARE DUE TO REFLECTOR EDGE DIFFRACTION THAT ADDS COHERENTLY AND TYPICALLY CAUSES A RELATIVELY STRONG MAIN BACKLOBE BEHIND THE REFLECTOR #ENTER 
 Demirci, S.; Cetinkaya, H.; Tekbas, M.; Yigit, E.; Ozdemir, C.; Vertiy, A. Back-projection algorithm for ISAR imaging of near-ﬁeld concealed objects. In Proceedings of the 2011 XXXth URSI General Assembly and Scientiﬁc Symposium, Istanbul, Turkey, 13–20 August 2011; pp. 
 I I ---,-.t---+----- -f--,.....--'.- J........""" l..............__L_f-__-~-.---- ....:........1-I J I :!. I :I! !TJ. 1.4..,',,: I 'I I i·.:·.··.. 
 NewYork.1971. 84.Ball.R.J..andD.J.Harris:Submillimeter Waves.TheRadioalldElectrOllic Ellgilleer, vol.46. pro379392.August/September 1976. 
 Stand-forward jamming is an ECM tactic in which the jamming platform is located between the weapon systems and the strike vehicles and jams the radars to protect the strike vehicles. The stand-forward jammer is usually within the le- thal range of defensive weapon systems for a considerable time. Therefore, only the use of relatively low-cost remotely piloted vehicles (RPVs) might be practi- cal. 
 , and j~ = pulse repetition frequency. The delay-line cancela not only  eliminates the d-c component caused by clutter (n = 0), but unfortunately it also rejects any  moving target whose doppler frequency happens to be the same as the prf or a multiple  thereof. Those relative target velocities which result in zero MTI response arc called hli11J  speeds and are given by  n = 1, 2, 3, ... 
 23. H. Urkowitz, “Analysis and synthesis of delay line periodic filters,” IRE Trans. 
 LIMITED DETECTION OF TARGETS WITH HIGH RADIAL VELOCITIES 3INGLE DOPPLER BLIND ZONE AT ZERO VELOCITY 'OOD GROUND 
 MTT-22, pp. 593-60 I, June, 1974.  38. 
 The predicted position at the n + 1st scan is x,, + x" Ts. (When accelera­ tion is important a third equation can be added to describe an a.-fJ-y tracker, where  y = acceleration smoothing parameter.)73 For a. = p = 0, the tracker uses no current informa­ tion, only the smoothed data of prior observations. 
 P.. Jr.. and R. 
 Johannessen, J.A.; R ∅ed, L.P .; Wahl, T. Eddies detected in ERS-1 SAR images and simulated in reduced gravity model. Int. 
 The symbol s  has been widely accepted as the designation for the RCS of an object,  although this was not so at first.2,3 The RCS is the projected area of a metal sphere that  is large compared with the wavelength and that, if substituted for the object, would  scatter identically the same power back to the radar. However, the RCS of all but the  simplest scatterers fluctuates greatly with the orientation of the object, so the notion  of an equivalent sphere is not very useful. The limiting process in Eq. 
 19.9  19.3 System Evolution  ....................................................  19.9  Basic Semiactive Seeker  ...................................  19.10 Unambiguous (Offset Video)  Receiver  ............... 
 0ALMER  :   2  AND THE COMMON .EXRAD 732 
 2.11 respect tothis standard allother modes ofindication provide varying amounts ofstorage gain,bymaking use, more orless imperfectly tobe sure, ofinformation gathered onrepeated pulse transmissions. Thus we say that Fig. 2.8describes theeffect ofscanning onstorage gain. 
 In Proceedings of the 2017 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Fort Worth, TX, USA, 23–28 July 2017; pp. 1634–1637. 15. 
 Aerospace and Electronic Systems , vol. 35, no. 2, pp. 
 SURVEILLANCE RADAR WITH A ROTATING ANTENNA BEAM DETERMINES ANGLE IN THIS MANNER 4HE ANGLE TO A TARGET IN ONE ANGULAR DIMENSION CAN ALSO BE DETERMINED BY USING TWO ANTENNA BEAMS  SLIGHTLY DISPLACED IN ANGLE  AND COMPARING THE ECHO AMPLI 
 TEM DESIGN SO THAT THE RADAR CAN ADAPT TO PREVAILING CONDITIONS BY SELECTING THE BEST FREQUENCY OR COMBINATION OF FREQUENCIES    WAVEFORM  SIGNAL PROCESSING  DETECTION  THRESHOLDS  AND SO ON  FOR THE TASK AT HAND !CHIEVING THIS OPTIMUM CONTROL IS IMPORTANT BECAUSE EXPERIENCE HAS SHOWN THAT (& SKYWAVE RADAR PERFORMANCE MAY DEGRADE DRA 
 Although it is preferable to eliminate cathode- stem leakage within the tube, it has sometimes been successfully trapped, ab- sorbed, or tolerated outside the tube. 6. Drift: Magnetron frequency varies with ambient temperature (of the cool- ing air or water) according to the temperature coefficient of its cavities, and it may also vary significantly during warmup. 
  ,  
 A total of N/2 concentric rings are required for a linear array of  N i- I elements.  There are several methods for generating phase shift that utilize the properties of circular  polarization. One of the first devices to employ circularly polarized waves propagating in  round waveguide was tlie Fox pliase sl~ifter.'~ This rotary-waveguide phase shifter was applied  in World War I1 by the Bell Telephone Laboratories in the FH MUSA, or Mk 8, scanning  TilEFI.ECTRONICAI.lY STEERED PHASED ARRAY ANTENNA INRADAR297 canprovide afast.electronically conlrolled phaseshiftbyvariation ofthehelixvollage.5oThe phaseshiftislargeenoughtoallowseveraltapsonasingletubetocontrolthephaseofseveral <lnlenna clements simultancously. 
 to extract target information results in a synthetic display in which  target information is presented with standard symbols and accompanying alphanumerics.  This is especially useful in an air-traffic-control display in which such information as target  identity and altitude is desired to be displayed. The positions of targets on a predetermined  number of previous scans might be shown on a synthetic display, or a line might be generated  to indicate the direction of the target's trajectory and the target's speed. 
 TRATION OF !2%03 
 V. Hobbs, R. A. 
 14.1. Choice ofFrequency .—One ofthemost controversial points in early radar development was the selection ofthe a-c frequency tobe used asprimary radar power, Atransformer correctly designed forthe frequency fwill behave tolerably atfrequencies upto3f,but will burn 555. 556 PRIME POWER SUPPLIES FOR RADAR [SEC. 
 These antennas can cover a sector of from 10 to 20 degrees or more, at a rate of  10 to 20 scans per second or greater. This is a rapid enough rate to permit essentially contin-  uous observation of the target. A radar which uses such a sector-scanning antenna to track the  path of airborne targets is sometimes called a track-wllile-scan radar. 
 P.: Radar Height Finding, chap. 22 of Skolnik, M. I. 
 Marcum, J. 1.: A Statistical Theory of Target Detection by Pulsed Radar, Mathematical Appendix,  IRE Trans., vol. IT-6, pp. 
 ING RADAR INTO A TARGET REACQUISITION MODE  !NOTHER FORM OF DECEPTION IS THE VELOCITY  GATE PULL OFF 6'0/  A COMBINATION OF 2'0/ AND 6'0/ IS ALSO POSSIBLE !NOTHER $%#- TECHNIQUE IS CALLED  INVERSE 
 It might be useful in preventing receiver saturation in  ch24.indd   32 12/19/07   6:00:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 Inthischapter, thesimpleradarequation willbeextended toincludemostoftheimpor­ tantfactorsthatinfluence radarrangeperformance. Ifallthosefactorsaffecting radarrange wereknown, it.wouldbepossible, inprinciple, tomakeanaccurate prediction ofradar perfoqnance. But,asistrueformostendeavors, thequalityoftheprediction isafunction of theamount ofeffortemployed indetermining thequantitative effectsofthevariouspa­ rameters. 
 B-scope. An intensity-modulated rectangular display with azimuth angle indicated by the horizontal  coordinate and range by the vertical coordinate.  C-scope. 
 It also depends on the wavelength.  142INTRODUCTION TORADAR SYSTEMS inthisfashion,theclutterfrequency canbemeasured directlybysampling thereceived echo signaloveranintervalofrange.Thesampled rangeintervalisselectedsothatclutterislikely tobethedominant signal.Fromthismeasurement ofclutterdopplerwithinthesampled range interval, compensation ismadeovertheentirerangeofobservation eitherbychanging the reference signalfromthecohoorbyadjusting thephaseshifterinsertedinoneofthearmsof thedelay-line canceler. Generally, theaveragedopplerfrequency orphaseshiftisobtained by averaging thesampled range-interval overanumberofpulserepetition periods. 
 901–905, 1985. 100. A. 
 I% 204,  March, 1972.  14. Schleher, D. 
 Brown, “Improvements in wireless telegraphy,” British Patent 14,449, 1899.  3. R. 
 At the same time the bat emits another.  sound, at a much higher frequency, so high, in fact,  that to the human ear it cannot be detected as a sound.  To use this high frequency for its ‘radar’ the bat has a  special construction of nose, throat, and ear; careful  study of these parts of a bat show that they are thus  designed even more intricately than any human physicist  could fashion a supersonic radar apparatus. 
  XPK =4      XPK       XSK    VSK 4    WHERE XSK  IS THE FILTERED POSITION   VSK  IS THE FILTERED VELOCITY   XPK  IS THE PREDICTED  POSITION   XMK  IS THE MEASURED POSITION   4 IS THE TIME BETWEEN DETECTIONS  AND  @  A   ARE THE POSITION AND VELOCITY GAINS  RESPECTIVELY 4HE SELECTION OF  @  A  IS A DESIGN  TRADEOFF 3MALL GAINS MAKE A SMALL CORRECTION IN THE DIRECTION OF EACH DETECTION !S A RESULT  THE TRACKING FILTER IS LESS SENSITIVE TO NOISE BUT IS MORE SLUGGISH TO RESPOND TO MANEUVERSDEVIATION FROM THE ASSUMED TARGET MODEL #ONVERSELY  LARGE GAINS PRO 
 If the requiretiients for switching speed and flexibility are similar to those  of a corivelitiori;tI clcctr oriic;illy stcered pliased-array radar, the problem of switching a  receiker betweell ports of tile bearii-forming array may be as difficult as that of providing the  pliitse shifting ill a corlventiorlal array radar.'''  111 principle, a surveillance radar with a fixed transmitting beam of width 0, and a number  N of fixed, narrow receiving beanis of width 0, covering the same volume (NO, = 0,). has  perfortilance equivalent to a radar with a single scanning transmit-receive beam of width 0,.  provided the comparison is made on a similar basis and the received signals are processed in  the optiniunl mariner in each case. 
 76. Lind. G.: Reduction of Radar Tracking Errors with Frequency Agility, IEEE Trans., vol. 
 R. F. Kinsey and A. 
 Similarly, the LOS range rT between a transmit  antenna of altitude hT and target of altitude ht is  rT = 130 ( √hT + √ht) (23.6) Thus, to prevent LOS truncation of the ovals, rR ≥ RR(max) and rT ≥ RT(max). These  expressions ignore both diffraction and multipath, which can significantly alter these  ranges, so they must be considered first-order approximations. A typical task for bistatic air surveillance is to select a baseline  L so that a receiver  with antenna altitude hR will match existing LOS coverage of a transmitter with antenna  altitude hT. 
 The RF circuitry that  generates the sum and difference signals in a mono pulse radar has been steadily improved, and  can be realized without excessive physical bulk. A popular form of antenna for monopulse is  the Cassegrain.  With the mono pulse tracker it is possible to obtain a measure of the angular error in two  coordinates 011 the basis of a single pulse. 
 The simulation benchmark160 includes two types of  ECM, namely SOJ and RGPO. The SOJ, mounted on an aircraft, transmits broadband  noise toward the radar. The SOJ flies an oval (race course) holding pattern in a clock - wise direction at an altitude of 3050 m and a speed of 168 m/s; it is approximately  ch24.indd   43 12/19/07   6:00:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 ,.  Ari example of the AGC portion of a tracking-radar receiver is shown in Fig. 5.5. 
 This mode was  motivated by a requirement to gather SAR-quality data over a large area within tight  data volume limits. One consequence of the ocean-viewing requirements was that VV‡  emerged as the favored polarization, since vertically polarized oceanic backscatter  tends to be larger at C band at steep incidence§ than horizontally polarized oceanic  backscatter. ERS-1 and -2 also carried radar altimeters (Section 18.3). 
 77. Cantrell, B. H.: A Short-Pulse Area MTI, NRL Report 8162, Nauul Rrseurcl~ Laboratory, Washington. 
 The successive difference in this term as M is var- ied from 2 to N is ElGM~l. The overall tendency of this term, therefore, is to produce an offset in the output with only a minor loss in logarithmic accuracy at the highest signal levels. A typical logarithmic detector may have an accuracy of ±4 dB, a dynamic range of 80 dB, and a bandwidth of 5 to 10 MHz at 30 MHz, derived from nine stages (Fig. 
 The ATR type of balanced  duplexer has higher power-handling capability than that of Fig. 9.6, but it has less bandwidth.  TR tubes. 
 It cannot have any high  peaks nearby that can mask another target close to the desired target. A waveform that yields  good resolution will also yield good accuracy, but the reverse is not always so.  EXTHACTION OFINFORMATION ANDWAVEFORM DESIGN 419 (0)Knifeedge(ridge) Ie)Thumblock(b)Bedofspikes Figure11.13Classesofambiguity diagrams: (a)knifeedge,orridge;(b)bedofspikes;(c)thumbtack. 
 1.3b, which plots target amplitude (y axis) vs. range (x axis), for some fixed  direction. This is a deflection.:inodulated display. 
 pp. 786--788.  Nov., 1964. 
 F.A.:TheAN/APN-81 Doppler Navigation System. IRETrans..vol.ANE-4. pp.202-211.December. 
 T. Kirubarajan, Y . Bar-Shalom, W. 
 center (apex) of the paraboloid. The qtised surface is made of such a size and distance from  the original reflector contour as to produce at the focus a reflected signal equal in amplitude  but opposite in phase to the signal reflected from the remainder or the reflector. The two  reflected signals cancel at the feed, so that there is no mismatch. 
 FILLED VOID EXISTS IN A DIELECTRIC MATERIAL 4HE EFFECT ON A PULSE WAVEFORM IS TO CHANGE THE PHASE OF THE REFLECTED WAVELET SO THAT TARGETS WITH DIFFERENT RELATIVE DIELEC 
 PLANE ERROR SENSING 4HESE MODES PROVIDE THE DIFFERENCE SIG 
 FM511774, rev. dated Aug. 2, 1976, Pasadena, Calif. 
 Scaling is a convenient way to handle other frequency bands. Where more exact doppler frequencies must be known, the exact transmitted frequency/0 should be used. It is important to note that, in addition to the target, there exist large interfering signals within the spectrum of interest: clutter and feedthrough (spillover or leakage of the rear signal into the front receiver through backlobes of the front antenna). 
 (Afrer Daley, et al.')  476INTRODUCTION TORADAR SYSTEMS Variation withfrequency andpolarization. FromFig.13.3,thevalueof0'0isseentobe essentially independent offrequency forvertical polarization, exceptatlowgrazing angles. Withhorizontal polarization, theclutterechodecreases withdecreasing frequency. 
 6.Kretschmer, F.F.:MTIWeightings, IEEETrans.,vol.AES-IO, pp.153-155, January, 1974. 7.Benning,c.,andD.Hunt:Coefficients forFeed-Forward MTIRadarFilters,Proc.IEEE,vol.57, pp.1788-1789, October, 1969. 8.Shrader, W.W.:MTIRadar,chap.17of"RadarHandbook," M.LSkolnik(ed.),McGraw-Hili Book Co.,NewYork,1970. 
 Middleton et al. in J. Appl. 
 ACCELERATIONS INTRO 
 It is also  noted that as many auxiliary antennas are needed as there are jamming signals to  be suppressed. In fact, at least N auxiliary patterns properly controlled in amplitude  FIGURE 24.2  Principle of SLC operation (connection a only in the closed-loop  implementation techniques); RX: receiverADAPTIVE SYSTEMAUXILIARY ARRAY OUTPUTSIDELOBESTARGET SIGNALJAMMERS VM ZWNW2W1 VNV2V1A1 A2 AN a + + −RX & ADCRX & ADCRX & ADCRX & ADC ch24.indd   14 12/19/07   6:00:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 RF Tube Selection. Table 4.1 summarizes the main differences among the leading RF tube types. The factors that most often dominate in tube selection are cost, bandwidth, spurious noise level, control electrodes, gain, size, voltage, and availability (not shown in the table). 
 Tactical Bistatic Radar Demonstrated, Def. Electron., no. 12, pp. 
 Although theymaynotalwaysbethoughtofasradars,theradio altimeter (eitherFMjCW orpulse)andthedoppler navigator arealsoradars.Sometimes ground-mapping radarsofmoderately highresolution areusedforaircraftnavigation purposes. S},i"Safety.Radarisusedforenhancing thesafetyofshiptravelbywarning ofpotential collision withotherships,andfordetecting navigation buoys,especially inpoorvisibility. Intermsofnumbers, thisisoneofthelargerapplications ofradar,butintermsofphysical sizeandcostitisoneofthesmallest. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°ÎÇ 4HE 02& IS  K(Z  APPROXIMATELY TWICE THAT OF MOST CONVENTIONAL ALTIMETERS  SLIGHTLY  LARGER THAN THE PULSE 
 , vol. 17,  pp. 1007–1017, 1982. 
 Sci. T echnol. Inf. 
  MEDIUM 
 Medium-PRF Range While Search.  A medium-PRF waveform is used to detect  targets competing with sidelobe clutter that would be undetectable in HRWS. MRWS  allows the detection of nose aspect targets at wide scan angles that are crossing the  radar line-of-sight, such that their low closing velocity places them in sidelobe clut - ter and tail aspect targets in lead pursuit engagements (an attack geometry where the  nose of the attacking aircraft is pointed ahead of the target’s present position). 
 ASTIADocument 152409. 58.Bacon.G.E.:Variable-elevation-beam AerialSystems for11Metres,J.lEE,vol.93.pI.iliA, pp.539-544. 1946. 
  
 150. T. W. 
 Zuder  (eds.), McGraw-Hill Book Co., New York, 1969.  137. Skolnik, M. 
 Loran transmitters have been installed in the Himalayas  to guide traffic across the Hump. There is, of course,  close co-operation between the pioneers of the two  systems, and even during the war years as many as 800  aircraft of Bomber Command were fitted with dual sets  which could handle both systems. Loran’s chief feature,  as its name implies, is that it is a long-range system, and  with only four times as many transmitters as Gee its  coverage is twenty times as great. 
 BIT !$ SIGN  BITS  THERMAL NOISE  SET AT  QUANTA 4OTAL  )NTEGRATION 'AIN.UMBER OF 0ULSES #OHERENTLY )NTEGRATED D"  )00S INTEGRATED PER #0) $OPPER &ILTER 7EIGHTING 
 There is a practical limit beyond which it becomes increasingly difficult to  achieve low sidelobcs even if a considerable amplitude taper is used.  Circular aperture. 5 • 8 The exam pies of aperture distribution presented previously in this sec­ t ion applied to distributions in one dimension. 
 5.11 Now the Fourier resolution ofCurve awill contain the repetition frequency and multiples thereof, whereas Curve bcontains f.+nf, but nomultiples off, (unless f~isamultiple ofj,). Thus the first or “clutter” filter that attenuates j,and multiples thereof, while leaving all else, will remove allsignals due tostationary objects, while leaving those due tomoving objects undisturbed. At ~ULfi point 2inFig. 
 4. R. R. 
 Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 12.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 illuminated by the feed, their removal generally has little impact on the gain. However,  circular and elliptical outlines/rims will produce modest sidelobes in both principal and  nonprincipal planes. 
 YEAR  CYCLE OF SOLAR ACTIVITY 6ARIOUS CORRELATED PARAMETERS HAVE BEEN DEFINED TO MEASURE THIS ACTIVITY  INCLUDING THE  CM SOLAR FLUX  SUNSPOT NUMBER  AND VARIOUS MAGNETIC INDICES &IGURE  SHOWS THE SMOOTHED AVERAGE SUNSPOT NUMBER PLOTTED FROM   THE YEAR OF THE FIRST VALIDATED /4(2 DETECTIONS OF MILITARY TARGETS ACHIEVED BY THE -53)# RADAR AT .2,   %NHANCED SOLAR ACTIVITY IMPACTS ON THE IONOSPHERE IN MANY WAYS  BUT ITS MOST SIG 
 , vol. 83, pp. 1771–1790, 2002. 
 When the blocking oscillator V,. istriggered byanincoming signal, itproduces apulse ofless than l-psec duration. The sharp positive pulse at1?ispassed through the2-~sec delay linetothe grid of~lb. 
 20.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 can be adapted to the radar context, where the main difference is the greater sensitiv - ity of radar observations to dynamical processes. This arises primarily because of the  extremely high dynamic range required to accommodate and preserve target echoes in  the presence of strong clutter and external noise. Ionospheric Structure. 
 pp.335-33~ February, 195~ 15.Kerr,D.E.(ed.):"Propagation ofShortRadioWaves," MITRadiation Laboratory Series,vol.13, pp.539-543, McGraw-Hili BookCompany, NewYork,1951. 16.Rabiner, L.R.,andC.M.Rade'r(eds.):"Digital SignalProcessing," IEEEPress,NewYork,1972. 17.Gardner, F.M.:DOPLOC UsesPhase-locked Filter,Electronic Ind.,vol.18,pp.96-99,October, 1959. 
 RECEIVER PAIRS  WHICH ARE PLOTTED AS ELLIPSES WITH A TRANSMITTER 
 6.11,  but TWTs for radar usually use a structure better suited for high power. The velocity of  propagation of electromagnetic energy is slowed down by the periodic structure so that it is  nearly equal to the velocity of the electron beam. It is for this reason that helix and similar  microwave circuits are called slow-wave structures or delay lines. 
 17.10 Main and guard antenna patterns.NONFLUCTUATING TARGET 2 _GUARD SNR MAINSNR LOSS 2 ^GUARDSNR MAIN SNR GUARDMAIN BEAM ANGLE GAINdBPROBABILITY OF DETECTION IN MAIN CHANNEL . FIG. 17.11 Single-channel sidelobe blanker.DETECTIONSOUT BLANK, BLANKC RANGE CORRELATOR(MOF N) BLANKING LOGIC BLANK = A-B BLANK = A-BA RANGE CORRELATOR(MOF N) BRANGE CORRELATOR(MOF N)STCTHRESHOLDSTCFUNCTION GENERATORDETECTIONSPRF NDETECTIONSPRF #2DETECTIONSPRF #1 CFARLINEAR DETECTORFFT . 
 n7 n7 n7n  n7n7n7n &)'52%     3OME COVERAGE AND TASKING OPTIONS FOR HYPOTHETICAL (& RADARS ON A FICTITIOUS  MID 
 IEEE T rans. Aerosp. Electron. 
  &)'52%   4HREE 
 M. Fuks, Wave Scattering from Statistically Rough Surfaces , New York:  Pergamon Press, 1979.  98. 
 POLARIZED ANTENNAS (( AND 66   EACH  ^  
 FORWARD AND FEEDBACK TERMS 4HEY ARE REFERRED TO AS  INFINITE  IMPULSE RESPONSE BECAUSE AN IMPULSE PRESENTED AT THE INPUT TO THE FILTER WILL PRODUCE AN INFINITE STRING OF NONZERO OUTPUTS IN AN IDEAL SITUATION&)'52%   'ENERAL DIRECT 
 The NRL 4FR data set is unique in that no other program has reported mea- surements made over so wide a range of frequencies, grazing angles, and wind speeds at the same time. Figure 13.4 shows the trends for both vertically and hor- izontally polarized sea clutter over a range of grazing angles down to 5°. The curves represent the centers of ±5 dB bands which contain the major returns for the three higher frequencies (L, C, and X bands—the UHF returns were a few decibels lower) and wind speeds above about 12 kn. 
 .' ---- 1 - 1 L---L--L-,  0 10 20 30 40 50 60 70 80 90  GRAZING ANGLE (degrees)  VERTICAL POLARIZATION  1-1 CULTIVATED  TERRAIN -3 ASPHALT  Ell CONCRETE Figure 13.8 Boundaries of measured  radar return at X band from various  GRAZING ANGLE (degrees) land (Corrrtesy ?f I. Katz.)  a soft, wet snowcover on vegetation tends to lower the return by as much as 6 dB.40 Measure-  ments made over snowfields near Thule, Greenland, showed the backscatter to be propor-  tional to the square of the frequency over the frequency range from UHF to X band and at  gra7irig angles from 5 to  Frequency dependence. Figure 13.1 1 shows an example of the frequency dependence of land  clutter for a particular grazing angle." Clutter from urban areas in these measurements is  independent of frequency; rural terrain shows no frequency dependence from L to X band;  RADAR CLUTTER 491 20 HORIZONTAL POLARIZATION ~CITY EZ2Z2lCULTIVATED TERRAIN r:::::::::::::;::::::jASPHALT c=JCONCRETE10 o -10 m ~-20 o b -30 -4U -50- 8090-60 __...1._. 
 7.8, 6 is the angle of scan measured from broadside and <|> is the plane of scan measured from the x axis. Von Aulock46 has presented a simplified method for visualizing the patterns and the effect of scanning. He considers the projection of the points on a hemisphere onto a plane (Fig. 
 Since the same TBP is maintained,  the original resolution is preserved. The method is ideal for altimetry, since the range  depth of the ocean’s surface is very much smaller than the time available in the pulse  repetition period. Clearly, the full deramp technique offers a considerable savings in  system bandwidth at all subsequent stages and at no cost in range resolution. 
 D/A con - verter additive thermal noise is independent of output signal frequency and produces  both phase and amplitude noise components. Frequency Multipliers.  Frequency multiplication allows signals to be increased  in both frequency and bandwidth. 
 In an N by M element planar array there might be a  separate snake feed for each of the N rows to obtain frequency steering in one coordinate, and  one phase shher for each of the M columns to achieve steering in the orthogonal plane.  Changing the frequency of a signal propagating through a length of transmission line is  a convenient method for obtaining a phase shift, but it is not always desirable to operate a  radar with a changing frequency. A phase shifting technique that uses a frequency change, but  which then converts back to a constant frequency, is the Huggins phase shifter shown in  Fig. 
 17.5 shows the clutter-plus-noise-to-noise ratio in range doppler coordinates for a 12-kHz PRF at an altitude of 6000 ft showing the main-beam clutter, altitude line, and sidelobe clutter. The range di- mension represents the unambiguous range interval RUJ and the frequency dimen- sion represents the PRF interval. As is evident, there is a range doppler region in which the sidelobe clutter is below thermal noise and in which good target detectability can be achieved. 
 The system losses have been omitted. The remaining sym­ bols have been defined ahovc or in Sec. 2.14. 
 #  !LTHOUGH USE OF MULTIPLE POLARIZATIONS DATES FROM THE EARLY DAYS OF IMAGING RADARS  THE MEASUREMENT OF PHASE BETWEEN THE RECEIVED SIGNAL WITH DIFFERENT POLARIZATIONS IS MORE RECENT  DATING FROM THE LATE S &EW  IF ANY  FULL 
 connect the output of the receiver and to apply it to the appropriate left or right deﬂector plates of the indicator. Various designs of aerial switch were used, but all provided a successive dwell time of about 20 ms on each aerial, equivalent to about 8pulses. Switch units type 35 and 35A (E K Cole designed receivers, see table 2.2) were driven by a motor rotating at 10 000 rpm through a 22:3 reduction gear. 
    %!3#/. 4ECH #ONV 2EV  .OVEMBER    PP n  2 * $OVIAK AND $ 3 :RNIC   $OPPLER 2ADAR AND 7EATHER /BSERVATIONS   /RLANDO  &,  !CADEMIC 0RESS    ( 2 7ARD  h! MODEL ENVIRONMENT FOR SEARCH RADAR EVALUATION v IN  %!3#/.  #ONVENTION  2ECORD  .EW 9ORK    PP n  )%%%  h)%%% 3TANDARD 2ADAR $EFINITIONS v 2ADAR 3YSTEMS 0ANEL  )%%% !EROSPACE AND %LECTRONICS  3YSTEMS 3OCIETY  2EPORT .O )%%% 3TD  
 hAc:: nrr.urrPn . 378 INTRODUCTION TO RADAR SYSTEMS  Let the event x = SN represent signal-plus-noise, and let the event y be the receiver input,  which may consist of either signaf ... pius-noise or noise alone. 
 Ifasimple cable-coupling circuit isused intheabsence ofalocking-pulse preampli- fier, care must betaken tomaintain adequate pulse amplitude. Circuit Design.-Any conventional type offreely running oscillator canbephase-locked byinjecting into itstuned circuit asufficient ylarge carrier pulse. There isacertain degree ofincompatibility between the requirements that the oscillator beextremely stable and yet precisely phasable. 
 The perfor - mance curves have been limited in almost all examples to the case of low solar activity,  since, in general, this is the most difficult time. The higher frequency availability and  performance afforded at high solar activity is illustrated in Figure 20.36, which treats  the case of July 1800 UTC for SSN = 100. Analysis of performance estimation curves for all combinations of (i) the four  seasons, (ii) day and night, and (iii) high and low solar activity153 reveals consistent  behavior: (i) Summer shows much greater losses than winter. 
 The image-recovery mixer represents a practical compromise which tends to balance its  slightly greater noise figure by its lower cost, greater ruggedness, and greater dynamtc range."  Utility of low-noise front-ends. The lower the noise figure of the radar receiver, the less need be  the transmitter power and/or the antenna aperture. Reductions in the size of the transmitter  and the antenna are always desirable if there are no concomitant reductions in performance. 
 SQUARE SLOPE  RETRIEVED FROM MICROWAVE RADIOMETRIC MEASUREMENTS COASTAL OCEAN PROBING EXPERIMENT  v * F !TMOSPH /CEANIC 4ECH   VOL   NO   PP n  . £È°£ÀÕ`Ê 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers.  RADAR RECEIVERS  6.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 at the image frequency −(w −w 0). 
 Itisreturned (perhaps after amplification) tothe comparison-pulse delay circuit which itcontrols. Thus, ifthe switch- ing occurs before the arrival ofthe sine pulse, VIconducts, Clbecomes more positive, and thedelay isincreased. Iftheswitching istoolate, Vt conducts and thedelay isdecreased. 
 LIKE PULSES 4HESE PULSES ARE INTEGRATED ADDED TOGETHER  BEFORE A DETECTION DECISION . £°£Ó  2!$!2 (!.$"//+  IS MADE 4O ACCOUNT FOR THESE ADDED SIGNALS  THE NUMERATOR OF THE RADAR EQUATION IS  MULTIPLIED BY A FACTOR  N%IN   WHERE  %IN  IS THE EFFICIENCY IN ADDING TOGETHER  N PULSES  4HIS VALUE CAN ALSO BE FOUND IN STANDARD TEXTS 4HE POWER  0T IS THE PEAK POWER OF A RADAR PULSE 4HE AVERAGE POWER   0AV  IS A BETTER  MEASURE OF THE ABILITY OF A RADAR TO DETECT TARGETS  SO IT IS SOMETIMES INSERTED INTO THE RADAR EQUATION USING  0 T   0AVFPS  WHERE FP IS THE PULSE REPETITION FREQUENCY OF THE PULSE  RADAR AND  S IS THE PULSE DURATION 4HE SURFACE OF THE EARTH AND THE EARTHS ATMOSPHERE CAN  DRASTICALLY AFFECT THE PROPAGATION OF ELECTROMAGNETIC WAVES AND CHANGE THE COVERAGE AND CAPABILITIES OF A RADAR )N THE RADAR EQUATION  THESE PROPAGATION EFFECTS ARE ACCOUNTED FOR BY A FACTOR  &  IN THE NUMERATOR OF THE RADAR EQUATION  AS DISCUSSED IN #HAPTER  7ITH  THE ABOVE SUBSTITUTED INTO THE SIMPLE FORM OF THE RADAR EQUATION WE GET   20' ! N %N & K4 & F 3 . ,EI ONP SMAX           AVS P    )N THE ABOVE EQUATION  IT WAS ASSUMED IN ITS DERIVATION THAT  "S y   WHICH IS GENERALLY  APPLICABLE IN RADAR ! FACTOR  ,S GREATER THAN UNITY   CALLED THE SYSTEM LOSSES  HAS BEEN  INSERTED TO ACCOUNT FOR THE MANY WAYS THAT LOSS CAN OCCUR IN A RADAR 4HIS LOSS FACTOR  CAN BE QUITE LARGE )F THE SYSTEM LOSS IS IGNORED  IT MIGHT RESULT IN A VERY LARGE ERROR IN THE ESTIMATED RANGE PREDICTED BY THE RADAR EQUATION ! LOSS OF FROM  D" TO MAY BE  D" IS NOT UNUSUAL WHEN ALL RADAR SYSTEM LOSS FACTORS ARE TAKEN INTO ACCOUNT  %QUATION  APPLIES FOR A RADAR THAT OBSERVES A TARGET LONG ENOUGH TO RECEIVE  N  PULSES -ORE FUNDAMENTALLY  IT APPLIES FOR A RADAR WHERE THE TIME ON TARGET  T O IS EQUAL  TO NFP !N EXAMPLE IS A TRACKING RADAR THAT CONTINUOUSLY OBSERVES A SINGLE TARGET FOR  A TIME TO 4HIS EQUATION  HOWEVER  NEEDS TO BE MODIFIED FOR A SURVEILLANCE RADAR THAT  OBSERVES AN ANGULAR VOLUME  7 WITH A REVISIT TIME  TS !IR TRAFFIC CONTROL RADARS MIGHT  HAVE A REVISIT TIME OF FROM  TO  S  4HUS  A SURVEILLANCE RADAR HAS THE ADDITIONAL CONSTRAINT THAT IT MUST COVER AN ANGULAR VOLUME  7 IN A GIVEN TIME  T S 4HE REVISIT   TIME TS IS EQUAL TO  TO77O   WHERE TO   NFP AND 7O  THE SOLID BEAMWIDTH OF THE ANTENNA  STERADIANS   IS APPROXIMATELY RELATED TO THE ANTENNA GAIN  ' BY '   O   7O 4HEREFORE   WHEN NFP IN %Q  IS REPLACED WITH ITS EQUAL  O  TS'7  THE RADAR EQUATION FOR A   SURVEILLANCE RADAR IS OBTAINED AS   20! %N& K4 & 3 . 
 BEAM NULLING  )N ADDITION TO THE INTERFERENCE SOURCE DIRECTIONS AND SOURCE  STRENGTHS  THIS TECHNIQUE CAN PROVIDE OTHER INFORMATION AS TO THE NUMBER OF SOURCES AND ANY CROSS CORRELATIONS COHERENCE  BETWEEN THE SOURCES 3UCH INFORMATION CAN BE USED TO TRACK AND CATALOGUE THE INTERFERENCE SOURCES IN ORDER TO PROPERLY REACT TO THEM THE JAMMER MAPPINGA FUNCTION RUNNING IN THE BACKGROUNDIS USEFUL TO SELECT THE MODES EG  ADMISSIBLE POINTING DIRECTIONS AND WAVEFORMS  OF MULTIFUNCTION RADAR AND FOR GENERAL SITUATION AWARENESS 3UPERRESOLUTION MIGHT BE ABLE TO RESOLVE MULTIPLE INDEPENDENT SOURCES DUE TO SIDELOBE SUPERPOSITION AND MASKING  PROBLEMS  SUPERRESO 
 The~fferences, \vhichshould deliberately bemadelarge, canbe exploited both byusing them asabasis forexcluding theundesired signals from the operating device and bymaking that device asinsensitive as possible tointerfering signals that arenot excluded. Unwanted signals can berejected byfrequency discrimination; thebulk oftheinterference isexcluded inthis way. How-ever, since itisalways necessary tohave a finite bandwidth toadmit thenecessary information, some interference is likely togetthrough totheanalyzer. 
 Motion Compensation.  The basic theory of SAR relies on the assumption that  the platform, and therefore the SAR antenna, is traveling along a straight-line flight  path at constant velocity parallel to the ground at constant altitude. This is not exactly  true, and for successful SAR imaging, it is necessary that the deviations of the antenna  from this nominal flight path be measured, recorded, and compensated for in the pro - cessing. 
 The usual method of measuring the direction of arrival is with narrow antenna beams. If  relative motion exists between target and radar, the shirt in the carrier frequency of the  reflected wave (doppler elTect) is a measure of the target's relative (radial) velocity and may be  used to distinguish moving targets from stationary objects. In radars which continuously track  the movement of a target, a continuous indication of the rate of change of target position is  also available. 
 Evaluation of Probabilities. As was mentioned in Sec. 2.2, if a threshold device is employed to make a decision as to the presence or absence of a signal in a background of noise, its performance can be described in terms of two probabilities: (1) the probability of detection, Pd9 and (2) the false-alarm probability, Pfa. 
 ll</> = interpulse phase change, llt = time jitter, Br = time-bandwidth product of pulse  compression system ( = unity for simple pulses,) llr = pulse-width jitter, A = pulse amplitude,  llA = intcrpulse amplitude change. In a digital signal processor the improvement factor is also  limited by the quantization noise introduced by the A/D converter, as was discussed in  Sec. 4.5. 
 The beamwidth in the plane containing the linear feed is  r*  Figure 7.6 Parabolic-reflector antenna.  RADAR ANTENNAS 235 Broadband signals.TheFourier-integral-transform relationship between theradiation pattern £(4))andtheaperture distributionA(z) asexpressed inEqs.(7.11)and(7.14)appliesonly whenthesignalisaCWsinewave.Ifthesignalwereapulseorsomeotherradarwaveform withaspectrum ofnoninfinitesimal width,thesimpleFourierintegralwhichappliestoaCW sincwavcwouldnotgivcthecorrectradiation patternnorwoulditpredictthetransient behavior. Inmostcasesofpractical interestthespectral widthofthesignalisrelatively small, withtheconsequence thatthepattern isnotaffected appreciably andtheFourier-integral relationships arcsatisfactory approximations. 
 DRIVING 
 This is done for one-, two-, and three-delay binomial-weight cancelers in Figs. 15.13 to 15.15. The values of VB given are the first blind speed of the radar (or where the first blind speed VB would be for a staggered PRF system if staggering were not used). 
 J. C. Moore. 
 The voltage applied tothe discriminator ismonitored bymeans ofavacuum-tube voltmeter and is always adjusted tothe same “value. The voltage output ofthe dis- criminator islinearly related tothe difference frequency. This discrim- inator output voltage isapplied toadifferentiating circuit consisting ofa resistor and condenser. 
 61. A. Farina, “Tracking function in bistatic and multistatic radar systems,” Proc. 
   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°Ó£ 4HIS LIMITATION LEADS TO THE NEED FOR ANOTHER MODE INTERLEAVED WITH 2'(02&  &ORTUNATELY  THE TIMELINE FOR OPENING TARGETS IS MUCH LONGER NET SPEED IS LESS  AND THE ENGAGEMENT RANGE IS MUCH SHORTER WEAPON CLOSURE RATES ARE TOO SLOW  /FTEN IN GENERAL SEARCH  -02& 
 The construction of the millimeter wave integrated ci r- cuit has been still up to now developed almost exclusively with Gallium -Arsenate.  With inte- gration the following has been achiev ed:  Reduction of costs  Reduction of the sizes   Homogeneous devices   Individual MMIC chips (2000 relevant) will be shown in the following figures.  . 
 The 12.8 m (42 ft) wide by 6.9 m (22.6 it) I~igli antenna reflector produces a 1.25" azimuth  beamwidtli and a shaped elevation beam extending beyond 40" so as to provide coverage to an  altitude of 18.6 km (61 ft). The upper corners of the antenna aperture have a square rather  than rounded outline. This causes the underside of the elevation beam to have a sharp drop-off  wliicli minimizes the ground-reflected energy that causes a lobed elevation pattern and a  degradation of the rairi-rejection capability of circular polarization. 
 Time sidelobes and weighting. The uniform amplitude of the linear FM waveform results in a  compressed pulse shape of the form (sin nBt)/nBr after passage through the matched filter, or  dispersive delay line, where B is the spectral band~idth.~' There are time, or range, sidelobes  to either side of the peak response with the first, and largest, sidelobe - 13.2 dB down from the  peak. The large sidelobes are often objectionable since a large target might mask nearby, smaller  targets. 
 8 * 
 A low-noise receiver front end (the first stage) is desirable for many civil applications, but in military radars the lowest noise figure attainable might not always be appropriate. In a high-noise environment, whether due to unintentional interference or to hostile jamming, a radar with a low-noise receiver is more susceptible than one with higher noise figure. Also, a low-noise amplifier as the front end generally will re- sult in the receiver having less dynamic range—something not desirable when faced with hostile electronic countermeasures (ECM) or when the doppler effect is used to detect small targets in the presence of large clutter. 
 Skolnik also includes a discussion  of ISAR images of ships obtained by the U. S. Naval Research Laboratory (NRL)  (Musman et al.22). 
 Figure 11.4  Introduction of reference planes with a distance of from the origin, with fixed  scattered field.   The incident wave can actually  be represented by a plane wave (for  € Rt→∞) at the reference  plane R0, and consequently a phase and amplitude reference can be created through R0. The  scattered field, however, can only be represented by a fictitious plane wave at R0, since the  reference plane is not necessarily in the far -field of the scatterer. 
 The reader should consult the three major compendia of  such data for more information both on results and on bibliography37,38,40 (note that  information is spread through many chapters of these volumes). Some early scattering-coefficient-measurement programs worth mentioning include  those of the Naval Research Laboratory,23,24 Goodyear Aerospace Corporation,20 Sandia  Corporation (near-vertical data),124,125 and particularly The Ohio State University.2,6  From 1972 to 1984, the largest program was at the University of Kansas.8,9,37,72,83, 98,126 Extensive programs were also in France (Centre National d’Etudes Spatiales,  Centre National d’Etudes des Télécommunications, Université Paul Sabatier),12,127 the  Netherlands,10,128 Canada Centre for Remote Sensing (CCRS; especially sea ice),26,129  and Switzerland and Austria (snow).130,131 Many of the results from these programs  appear in digests of the International Geoscience and Remote Sensing Symposia  (IGARSS; IEEE Geoscience and Remote Sensing Society) and journals such as  IEEE Transactions on Geoscience and Remote Sensing  and on Ocean Engineering,  International Journal of Remote Sensing, Remote Sensing of Environment , and  Photogrammetric Engineering and Remote Sensing . Although calibrations for some of the older data were doubtful, summary presen - tations are not available for newer data. 
 __ THE RADAR EQUATION 41  --r -T-~--1··--r·--r---i-1-~--,,  I ' I '  I \  I I  I I  Peak due to / \ --Peak due  gos lank ----1--- ... -r lo fuselage  I I  cl I I I  I I  0 ! 1  I I I  I I I  \ / I  I I I I o I  I / I  I I I I  I I I I \ I I I Peak due to  lroling edge  cl wing  I  f  I· I.  I  I  I I I I I  I J I I  \ / /1 I --o--o  I I I '°\ I  \I I I / ,, lf I I / \  I o" \ f  J \ I ,,,/ '\, I  \ ---·/ • 'J ....... 
 The carrier-based E-2C aircraft (Fig. 16.1) uses AEW radar as the primary sensor in its airborne tactical data system. These radars with their extensive field of view are required to detect small aircraft targets against a background of sea and land clutter. 
 OF 
 Inoperation, the antenna ismoved upand down inthe expected azimuth ofsearch atarate ofone oscillation inten seconds. AnRHI display isused (Fig. 6.23). 
 75  CHO 938-1 AES.  87. Guenther. 
 This assumption permits construction of scattered fields by assuming  that the current over a rough plane surface has the same magnitude as if the surface  were smooth, but with phase perturbations set by the differing distances of individual  FIGURE   16. 5 Normal-incidence reradiation patterns of facets FIGURE   16. 6a Facet model of a radar return ch16.indd   9 12/19/07   4:54:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 BEAM CLUTTER IN THIS RANGE GATE IS THE VECTOR SUM OF THE SIGNALS RECEIVED FROM ALL FOUR CLUTTER PATCHES /WING TO THIS HIGH DEGREE OF RANGE FOLDOVER  ALL RANGE GATES WILL HAVE APPROXIMATELY EQUAL CLUTTER &)'52%  0LAN VIEW OF RANGE 
 11.1 la). The  ambiguity diagram is represented in Fig. 1 1.1 lb. 
 Radar System Engineering  Chapter 9 – Synthetic Aperture Radar  74       Figure 9.1  Comparison of analog and Digital Beam -forming system conepts.       . Radar System Engineering  Chapter 9 – Synthetic Aperture Radar  75     10 Synthetic Aperture Radar   10.1 Resolution Limits of Conventional Radar D evices   The achievable resolution capability of conventional pulse Radar devices is, as already d e- scribed, determined by:   - Pulse duration τ for range resolution  - Half- power bandwidth θ H for the resolution of the angle   The resolution in the propagation direction, i.e. 
 3URFACE 3EARCHn n n n n n n n )NVERSE3!2n n n n n n n n '-4) n n n n n n n n &IXED 4ARGET4RACKn n n n n n n n '-44 n n n n n n n n 3EA 
 Skolnik, M. I.: Theoretical Accuracy of Radar Measurements, IRE Trans., vol. ANE-7, pp. 
 ULES IN ONE SUBARRAY )N RECEIVE  THE SIGNAL FROM EACH OF THE  SUBARRAYS IS FED INTO A RECEIVE BEAMFORMING NETWORK 4HE 42 MODULE CONTAINS PREDRIVER  DRIVER  AND FINAL TRANSMIT A MPLIFIERS  TRANSMIT RECEIVE SWITCHING  LOW 
 . 
 Publ. 216, pp. 188-192, October 1982. 
 Evidence is provided to demonstrate that more closely spaced elements reduce the variation of impedance due to scanning in spite of the increase in mutual coupling. Elliott and coworkers61'62 have developed design procedures for slot arrays which are fed by either air-filled or dielectric-filled waveguide. These procedures take into account the differences in mutual coupling for central elements in an array as well as for the edge elements. 
 Geosci. Remote Sens. 2001 ,39, 8–20. 
 20.19  20.3 Height Accuracy Performance Limitations  ..............  20.19  Fundamental Accuracy of Se quential Lobing   ......  20.20  Fundamental Accuracy of Simultaneous  Lobing  ............................................................. 
 Any use is subject to the Terms of Use as given at the website. Radar Receivers. 6.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 This range-dependent filter characteristic is given by  | ( ) | sin ( / ) sin ( ) F f f R c f TR m m m2 2 24 2 4 = = π π  (6.9) where fm = modulation frequency (Hz)  R = range (m)  c = propagation velocity, 3 × 108 (m/s)  T = time delay = 2R/c (s) A short time delay can tolerate much higher disturbances at low modulation fre - quencies, as illustrated by the two cases in Figure 6.4. Consequently, the effects of  STALO stability need to be computed for several time delays or ranges to ensure suf - ficient stability exists for the intended application. 
 12H.Schwartzman. L..andJ.Stangel: TheDomeAntenna, MicrowQl'e J.,vol.18.pp.31-34,October, 1t>75. 129.Schwartzman. 
  
 Ê, ,Ê 
 TIVENESS /PERATING OVER A WIDE RANGE OF FREQUENCIES MAKES COUNTERMEASURES MORE DIFFICULT THAN IF OPERATION IS AT ONLY ONE FREQUENCY !GAINST NOISE JAMMING  CHANGING FREQUENCY IN AN UNPREDICTABLE MANNER OVER A WIDE RANGE OF FREQUENCIES CAUSES THE JAM 
 Of these, the loss of altitude coverage is the more serious. Both factors have caused the cosecant-squared pattern to be abandoned in favor of one that directs more energy upward. The advent of stacked-beam radars, which achieve their coverage pattern by use of multiple beams, has liberated STC from the restrictions of the antenna pat- tern. 
 Appl. Earth Obs. Remote Sens. 
 endcell endcell When the crystal isdriven atitsFIC. 16.10.—Laboratory-typc supersonic de- lay line, resonant frequency, itacts asa half-wave acoustical transformer; thus the delay line isproperly termi- nated ateach end bythe end cells. The wave entering anend cell is broken upand absorbed bytheskew back ofthe cell. 
 The force equation is Hev~uz =eE+—,T R(1) where Ristheradius oftheorbit oftheelectron (Rispositive fororbits curving down). Where the path ofthe electron isastraight line, the condition isobtained byletting R=~.Equation (1)then reduces to v=Et/H. Inspection ofEq. 
 This is the probability of associating (M, v) with H2 when H1 is the true hypothesis. PTB is related to SNR, F, and the auxiliary gain w = GAIGt normalized to the gain G, of the main beam. To complete the list ofMAGNITUDE MAIN ANTENNA AUXILIARYANTENNA ANGLE FIG. 
 J.: The Systematic Design of the Butler Matrix, IEEE Tra11s .. vol. A P-11. 
 If KN pulses are in the 3-dB beam - width, K pulses are summed (batched) and either a 0 or a 1 is declared, depending  on whether or not the batch is less than a threshold T1. The last N zeros and ones are FIGURE 7.7  Angular accuracy for two pulses separated by 0.5 beamwidths ch07.indd   8 12/17/07   2:13:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 11. Vendor transistor datasheet, Integra Technologies, Inc , www.integratech.com. 12. 
 NALS FROM THE MANY (& TRANSMITTERS THROUGHOUT THE WORLD "OTH MICROWAVE AND (& RADARS CAN BE LIMITED BY THE LARGE ECHO SIGNALS FROM LAND OR SEA  THOUGH IN (& SKYWAVE RADARS  THE PROBLEM IS PARTICULARLY SEVERE $OPPLER PROCESSING IS ESSENTIAL UNDER SUCH CONDITIONS &OR SOME AIRCRAFT  THE RADAR CROSS SECTION AT (& IS SIGNIFICANTLY LARGER THAN THAT AT MICRO 
 IRE, vol. 37, pp. 852-855, August, 1949. 
 C. M.: A Low Noise CW Doppler Technique, Natl. Conf Proc. 
   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°Ó£ 4HE TERMS  ACTIVE ELEMENT PATTERN AND  ELEMENT IMPEDANCE REFER TO AN ELEMENT IN  ITS OPERATING ENVIRONMENT IE  IN AN ARRAY WITH ITS NEIGHBORING ELEMENTS EXCITED  )N  THE ARRAY  EACH EXCITED ELEMENT COUPLES TO EVERY OTHER ELEMENT 4HE COUPLING FROM SEVERAL ELEMENTS TO A TYPICAL CENTRAL ELEMENT  ELEMENT   IS SHOWN IN &IGURE  4HE # MN PQ ARE MUTUAL 
 An amplitude effect, due tothefinite beamwidth, will bediscussed later.. SEC. 16.13] BEATING DUETOFINITE. 
 Cutrona, L. J., W. E. 
 TRACK SYSTEMS WERE DEVELOPED  !LL REQUIRED INITIALIZATION OF THE TRACK DATA  WHICH WAS CONVENIENTLY PROVIDED BY THE TARGETS LAUNCH COORDINATES (OWEVER  IF THE TARGET RETURN MOMENTARILY FADED OR THE TRANSPONDER SIGNAL WAS INTERRUPTED DURING FLIGHT SO THAT TRACK WAS LOST  THERE WAS NO WAY TO REINITIALIZE NEW TRACK DATA AND SUBSEQUENT LOCATION ESTIMATES BECAME BIASED OR WERE LOST 4HESE SYSTEMS WERE SUBSEQUENTLY REPLACED WITH PRECISION MONOSTATIC RADARS AND OPTICAL TRACKERS ÓÎ°ÇÊ /, 
 Remote. Sens. Lett. 
 Marconi recognized the potentialities of short waves for radio detection and strongly  urged their use in 1922 for this application. In a speech delivered before the Institute of Radio  Engineers, he said:'  As was first shown by Hertz, electric waves can be completely reflected by conducting bodies. In  some of 'my tests I have noticed the effects of reflection and detection of these waves by metallic  objects miles away. 
 CLUTTER FLUCTUATIONS CAN BE DETERMINED BY SUB 
 Itisdesirable that such gating betione inthe video amplifier rather than inthe i-famplifier, toavoid generating apulse when ac-w signal ispresent. Finally, theoperation ofthegain control early inthe i-famplifier isofvalue when strong c-w signals arepresent. The gain control should beofatype that does not reduce the output capabilities ofthecent rolled stages; grid gain cent rolissatisfactory inthis respect. 
 In contrast to the CAGO -CFAR, the OS- CFAR has the advantage of effe c- tive thres hold formation, allowing accurate fitting of the threshold in the clutter sc enario.  The OS -CFAR only shows inadequacies in the case of extreme scenarios, where the threshol d- ing process is required to fulfil conflicting requirements. This is because on one hand, a timely  following of jumps in clutter level without undue lead or lag can only be achieved by a rank - selection r ≤  A/2. 
 A. Monzingo and T.W. Miller, Introduction to Adaptive Arrays , New York: John Wiley &   Sons, 1980. 
 ETERS SUCH INFORMATION IS EXTREMELY HELPFUL WHEN DESIGNING A RADAR FOR REMOTE SENS 
 H.: A Theory of Target Glint or Angular Scintillation in Radar Tracking, Proc. I RE, vol.  41, pp. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.64  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 FIGURE  2.68 Linear clutter sequence amplitude and phase for 20 hits   per beamwidth ( after T. M. 
 The losses in propagating through the ionosphere change with time, and  the transmitter must have sufficient excess power to overcome the maximum loss expected.  Fading of the HF signals can occur due to the rotation of the plane of polarization over tt~e  ionized region of the propagation path. Multipath interference from more than one refracting  region, as well as dynamic irregularities in the ionospheric propagation path, are two other  sources of fading. 
 2. DBS Imaging Model For airborne WAS radar system, the radar dwells in a particular beam position continuously with a set of coherent processing intervals (CPIs). The surveillance region is searched by sequentially looking in all azimuth angles, the working mode of the WAS radar is illustrated in Figure 1. 
 SIGHT ,/3  IS D  4HE VARIABLE COMPONENT OF THE RADAR 
 Bayma and P. A. McInnes, “Aperture size and ambiguity constraints for a synthetic aperture  radar,” in Proc. 
 The two frequencies, when combined inthe mixer, 1Wenote that twotypes of“frequency analysis” areuseful inanalyzing thisand other systems. OneistheFourier method, inwhich some curve isdecomposed into asumofsinewaves, each ofconstant amplitude andfrequency andextending intime from –cato +cO. .%rcording totheother method, frequently useful indiscussing f-msystems, wesaythat anyfunction oftime canberepreserited byafunction oftbe form acosdwhere aanduarefanctions oftandaresochosen astogetthebest fit atanyvalue oft.Incases where thelatter procedure isuseful, aandwareslow functions oft.. 
 The use of a synthetic antenna and/or pulse com- pression places additional requirements on some of these components, especially with respect to coherence and stability. It is the purpose of this section to present a block diagram of the portions of the radar system that precede the signal processor. A block diagram and several variants are described. 
 I.: An Analysis of Bistatic Radar, Appendix, IRE Trans., vol. A NE-8, pp. 19 27, March,  1961. 
 CIES AND WIND SPEEDS OVER WHICH THE CONCEPTS OF GEOMETRICAL OPTICS MAY BE APPLIED 4HIS WAS DONE IN 7ETZEL   WHERE IT IS SHOWN HOW  DIFFRACTION  RATHER THAN GEOMETRICAL  SHADOWING  CONTROLS PROPAGATION INTO AND OUT OF THE TROUGHS OF THE WAVES UNDER MANY OF THE USUAL FREQUENCIES AND WIND SPEEDS ENCOUNTERED IN PRACTICAL RADAR OPERATIONS AT LOW GRAZING ANGLES &OR  EXAMPLE  SHADOWING WILL TAKE  PLACE AT + A BAND FOR ANY WINDS  ABOVE  KT  YET WILL HARDLY EVER OCCUR AT , 
 In the development of SAR, several interesting techniques  ch17.indd   2 12/17/07   6:48:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 
 3. Boutacoff, D. A.: Backscatter Radar Extends Early Warning Times, Def. 
 In terms of the bistatic  triangle, the required receive beam-pointing angle is21  q qq qR TT T R TL R R L= −+ −  −21tancos sin (23.19) The minimum receive beamwidth ( ∆qR)m required to capture all returns from a  range cell intersecting the common beam area is approximated by21  ( ) ( t an( ) ) ∆ ∆ q t b qR m u TT R c RR ≈ +/ /2  (23.20) where tu is the uncompressed pulse width and ∆qT is the transmit beamwidth. The  approximation assumes that respective rays from the transmit and receive beams are  parallel. The approximation is reasonable when ( RT + RR)  L or when L  ctu. 
 VERSIONS THAT RUN ON -ICROSOFT 0# 
 On the basis of the loss in gain, a three- or  four-bi t phase shifter should be satisfactory for most applications.  Phase quantization errors also result in an increase in the rms sidelobe level and in the  peak sidelobe level. With the assumptiotis that (1) the energy lost by the reduction in main  beam gain shows up as an increase in the rrns sidelobe level, (2) the element gain is the same for  the riiain bear11 and the sidelobes (within the region of space scanned by the array), (3) an  allowance of one dB for the reduction in gain due to the aperture illumination, and (4) one dB  for scanning degradation, then the sidelobe level due to the quantization can be expressed as  d' rms sidelobe level 2: --- -- 22B~  where N = total riurnber of elenien ts in the array. 
 D.Kirkpatrick. (i.M.:FinalEngineering ReportonAngular Accuracy Improvement, GeneralElectric Co.ReportallCOlltract D.A.36-039-sc-194. Aug.I.,1952.(Reprinted inref.18.) 24.Ricardi.L.1.,andL.Niro:DesignofaTwelve-horn Monopulse Feed,IREConI'.Rec.•I.pp.49-56, 1961.(Reprinted inref.18.) 25.Hannan, P.W.,andP.A.Loth:AMonopulse Antenna HavingIndependent Optimization oftheSum andDilTerence Modes,IREConI'.Rec.•1.pp.56-60,1961.(Reprinted inref.18.) 26.Howard. 
 G-Scope. A rectangular display in which a target appears as a laterally centralized blip when the radar  nntenna is ainled a1 it in a7iniuth, and wings appear to grow on the pip as the distance to the target is  dit~lirlished; tlorizori~al and vertical rtillli~lg errors are respectively indicated by llorizotllal and verti-  cal displacement of the blip.  If-scope. 
 P. G., and R. J. 
 For  many years, SOLAS-compliant radars have had the capability to employ user-defined  maps as an underlay to the radar image. Many maps can be created and stored for  future use. Although this facility is still widely used, the use of vectorized electronic  chart data as a radar underlay is becoming more common. 
 550 INTRODUCTION TO RADAR SYSTEMS  wideband filter is designed to include most of the spectrum of tlle interfering signal. Its purposc  is to preserve the short duration of the narrow impulsive spikes. These spikes arc tl~en clippcd  by the limiter to remove a considerable portion of their energy. 
 SPACE RESOLUTIONS  WERE  M   M  AND  M !NTENNA GAINS WERE  
 101-104, IEE Conference Publication no. 155.  16. 
  D   V !C   D 4!",%  3PURIOUS 3IGNAL #OMPONENTS 'ENERATED BY )1 .ONLINEARITY. 
 When a number of single-delay feedforward cancelers are cascaded in series,  the overall filter voltage response is k2n sinn (p fdT), where k is the target amplitude,   n is the number of delays, fd is the doppler frequency, and T is the interpulse period.22  The cascaded single-delay cancelers can be rearranged as a transversal filter, and the  weights for each pulse are the binomial coefficients with alternating sign: 1, −1 for  two pulses; 1, −2, 1 for three pulses; 1, −3, 3, −1 for four pulses, and so on. Changes  of the binomial feedforward coefficients and/or the addition of feedback modify the FIGURE  2.31  Direct Form 2 or canonical form of any MTI filter design−a1 −a2−aNx(n)b1 b2 bN Z−1Z−1y(n) Z−1b0 bN−1 FIGURE  2.32 MTI shown as cascaded form of second order section: ( a) is for even order and ( b) is for  odd order with first order section at end.−a1i −a2ix(n)b2i Z−1Z−1b0 −a1K −a2Kb1K b2K Z−1Z−1y(n) Hi(z) i = 1, 2, …, K−1 HK(z)b1i (a) −a1i −a2ix(n)b1i b2i Z−1Z−1b0 −a1Kb1K Z−1y(n) Hi(z) i = 1, 2, …, K−1 HK(z) (b) ch02.indd   34 12/20/07   1:44:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 It is equal to half the pulse length of the radar (164 yards permicrosecondofpulselength).Electronicconsiderationssuchastherecoverytime of the receiver and the duplexer (TR and anti-TR tubes assembly)extend the minimum range at which a target can be detected beyond therange determined by the pulse length. Sea Return Sea return or echoes received from waves may clutter the indicator within andbeyondtheminimumrangeestablishedbythepulselengthandrecoverytime. Side-Lobe Echoes Targets detected by the side-lobes of the antenna beam pattern are called side-lobeechoes.Whenoperatingnearlandorlargetargets,side-lobeechoesmay clutter the indicator and prevent detection of close targets, withoutregard to the direction in which the antenna is trained. 
 Z (a)E1 EO . The independent variable M is the order of the stage at incipient saturation and will take on only integer values from 1 to N. A nonlogarithmic term in the form of a power series in 1/G has only a minor effect on logarithmic accuracy. 
  
 Here we have stations  putting out, say, 100 kilowatts, and taking up, perhaps,  an acre of ground-space, using giant water-cooled valves  and enough machinery to fill quite a respectable public-  utility power-station. But in radar we use apparatus that  will almost fit into a suitcase, and yet transmit with a  power of several hundreds of kilowatts! The reason 1s  that with pulse transmission, as the name implies, we  are not transmitting continuously, but in a series of  giant pulses. The transmitter can be heavily overloaded  during the minute period of the pulse, for there then  follows a comparatively long interval of time when the  oscillator is quiescent and doing no work at all. 
 The antenna of effective aperture area Ae intercepts a portion of this power in an amount given by the product of the three factors. If the maximum radar range /?max is defined as that which results in the received power Pr being equal to the receiver minimum detectable signal Smin, the radar equation may be writ- ten . PtGt A6(T R4m*x = ' 2 (1-2) (4TT)Xn . 
 NITIONS AND RELATIONSHIPS 4ABLE  SHOWS 7OODWARDS &OURIER TRANSFORM RULES AND  PAIRS 4HESE RELATIONSHIPS SIMPLIFY THE APPLICATION OF SIGNAL ANALYSIS TECHNIQUES )N  MOST CASES  IT WILL NOT BE NECESSARY TO EXPLICITLY PERFORM AN INTEGRATION TO EVALUATE THE &OURIER TRANSFORM OR INVERSE &OURIER TRANSFORM#HARACTERISTIC 6ALUE 4RANSMIT ,&- BANDWIDTH  TO  -(Z 2EFERENCE ,&- BANDWIDTH  TO  -(Z 4RANSMIT WAVEFORM SWEPT BANDWIDTH  "   -(Z 2EFERENCE WAVEFORM SWEPT BANDWIDTH  "REF  -(Z   4RANSMIT PULSEWIDTH  4  §S 2EFERENCE PULSEWIDTH  4REF  §S 4RANSMIT WAVEFORM ,&- SLOPE  -(Z§S UP 
 17. Sondergaard. I-'.: A Dual Mode Digital Processor for Medium Resolution Synthetic Aperture  Radars. 
 Waterman: "Airborne Radar," D. Van Nostrand Co., Inc.,  Princeton, N.J., 1961.  68. 
 The earliest systems all used magnetrons, as has been noted, and amplifier chain system development had to await the development of suitable high-power pulsed-amplifier tubes. Although many varieties were developed, the successful kinds were klystrons, TWTs, and CFAs. Triodes and tetrodes2 have also been used in radars at frequencies below 600 MHz. 
 ING CLUTTER . Ó°n{  2!$!2 (!.$"//+  IMPROVEMENT FACTOR RESTRICTION  AS DISCUSSED IN 3ECTION  #ONSEQUENTLY  FOR THE  LIMITED )& DYNAMIC RANGE TO HAVE THE DESIRED EFFECT ON THE OUTPUT RESIDUES  THE LIMIT LEVEL MUST BE SET  TO  D" BELOW THE IMPROVEMENT FACTOR LIMIT OF THE LINEAR SYSTEM 4HE NET RESULT IS THAT SOME OF THE CLUTTER SUPPRESSION CAPABILITY OF THE -4) RADAR MUST BE SACRIFICED IN EXCHANGE FOR CONTROL OF THE OUTPUT FALSE 
 427-439,  April, 1969.  61. Greene, J.: Antenna Noise Temperature, AIL Advertisement, Proc. 
  
 The requirements for stabilization depend in  part on the nature of the application. Requirements differ whether the radar is used for surface  search, air search, tracking, or height finding.  There are three kinds of platform motion that can affect the location of the antenna beam. 
 SCAN PROBLEM   STEP SCANNING    FLOOD 
 This finding established the precedence for subsequent PBR developments: doppler  exploitation of stable, narrow-band carrier lines in TV transmissions and range/doppler  exploitation of the wider band, noise-like spectrum of FM transmissions. The modulation content of many broadcast transmitters changes as a function of  time, thereby complicating matched filtering by the PBR’s receiver. Specifically, the  receiver must sample and store a segment of the direct path waveform and then cross- correlate it with the returned echo, all in real time. 
 These fluctua - tions caused by the target only, excluding atmospheric effects and radar receiver noise  contributions, are called target noise. ch09.indd   26 12/15/07   6:07:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 f~ Unequally spacedarra)'s.1 36139Mostarrayantennas haveequalspacings between adjacent elements. Unequal spacings havesometimes beenconsidered inordertoobtainagivenbeam­ widthwithconsiderably fewerelements thananequallyspacedarray,ortoapproximate a desiredpattern without theneedforanamplitude-tapered aperture illumination. Sincethe minimum element spacing isaboutone-half wavelength, unequally spacedarraysgenerally havefewerelements thanequallyspacedarraysofthesamesizeaperture. 
 The silicon bipolar power transistor is a common device choice for a solid-state system. At the lower frequencies, especially below 3 GHz, this component provides adequate performance at the lowest cost among competing solid-state technologies. Amplifier design is realizable for frequencies up through S Band, where the tradeoff between device performance and overall system cost begins to reach a point of dimin- ishing returns. 
 TANCOS COS YS XS  4HE ANGLE OF SCAN  P  IS DETERMINED BY THE DISTANCE OF THE POINT COS  @XS  COS @YS  FROM  THE ORIGIN 4HIS DISTANCE IS EQUAL TO SIN  P &OR THIS REASON  A REPRESENTATION OF THIS SORT IS  CALLED SIN  P  SPACE ! FEATURE OF SIN  P  SPACE IS THAT THE ANTENNA PATTERN SHAPE IS INVARIANT &)'52%  4EN 
 Schrank, Electronics Systems Group, Westinghouse Electric Corporation (CHAPTER 6) Robert J. Serafin, National Center for Atmospheric Research (CHAPTER 23) William W. Shrader, Equipment Division, Raytheon Company (CHAPTER 15) William A. 
        
 To compensate for the impedance variation, it is necessary to have a compensation network that is also dependent on scanning. One method uses a thin sheet of high-dielectric-constant material (e.g., alu- mina) spaced a fraction of a wavelength from the array, as shown in Fig. 7.21.This is in contrast to the method used by Munk63'64 and described under 4'Analytical Techniques." The properties of a thin dielectric sheet (less than a quarter wave in the medium) are such that to an incident plane wave it appears as a susceptance that varies with both the plane of scan and the angle of scan. 
 176- 196, December, 1957.  46. Condie. 
 F. J. Janza, R. 
 F. Junyent, V . Chandrasekar, D. 
 TO 
 7 .18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 The first threshold is fixed (equals m + T1/K in Figure 7.21) and yields Pfa = 10−6  when the reference cells are independent and identically distributed. The second  threshold is adaptive and maintains a low Pfa when the reference samples are cor - related. The device estimates the standard deviation of the correlated samples with  the mean deviate estimator, where extraneous targets in the reference cells have  been excluded from the estimate by use of a preliminary threshold T2. 
 Thustoachieve thebenefits fromfullcontroloftheaperture illumination ofaphasedarray,mutualcoupling amongtheelements mustbeproperly takenintoaccount. Mostanalyses ofmutualcoupling areconcerned withthechangeinimpedance atthe inputtotheelement.74-77Itisimportant toknowhowtheimpedance changes inorderto properly matchtheimpedance ofthetransmitter andthereceiver totheradiator. Theeffects ofdiffraction ofenergybyneighboring elements shouldalsobeconsidered asamutual coupling problem. 
 It was set up in 1936, having previously been known as the coastal area of the RAF. On 1stSeptember 1937 its role was de ﬁned in an Air Ministry Directive to the Air Of ﬁcer Commanding-in-Chief as ‘trade protection, reconnaissance and co-operation with the Royal Navy ’. The provision of airborne reconnaissance reports of surface ships was a key requirement and this could be seriously hampered by poor visibility, bad weather and darkness. 
 TIONS  THE  "RAGG MODEL WAS INTRODUCED INTO THE MICROWAVE REGIME BY MANY WORKERS  IN THE MID 
 J. Crony, “Civil marine radar,” in The Radar Handbook , 1st Ed., M. I. 
 Fruge, and D. Cooke: Stability Measurement . Problems and Techniques for Operational Airborne Pulse Doppler Radar, IEEE Trans., vol. 
 It could be used to give anindication of the magnetron frequency or to produce an echo signal for tuning the klystron. The latter application was particularly useful if strong stable targets were not available to set the tuning, which had to be undertaken regularly during operation of the radar. The wavemeter as installed in a Wellington XIV can be seen in ﬁgure 4.2(b). 
 Theseare(I)themaximum amount ofpowerthereceiver inputcircuitry canwithstand beforeitisphysically damaged oritssensitivity reduced (burnout) and(2)theamount oftransmitter noiseduetohum,microphonics, straypick-up, andinstability whichentersthereceiver fromthetransmitter. Theadditional noiseintroduced bythetransmitter reduces thereceiver sensitivity. ExceptwheretheCWradaroperates with relatively lowtransmitter powerandinsensitive receivers, additional isolation isusually requircd hctwe'en thetransmitter andthereceiver ifthesensitivity isnottobedegraded either byburnout orbyexcessive noise. 
 228 INTRODUCTION TO RADAR SYSTEMS  achievement of extremely low sidelobes requires the antenna to be well constructed so as to  maintain the necessary mechanical and electrical tolerances. It takes only a small deviation of  the antenna surface to have an increase of the peak sidclobc of a very low sidelobe antenna.  Furthermore, there must be no obstructions in the vicinity of the antenna that can divert  energy to the sidelobe regions and appear as high sidelohes. 
 TEROMETER WAS ADOPTED BY %5-%43!4 IN THE EARLY S AS A REQUIRED OPERATIONAL CAPABILITY  WITH OPERATIONAL ACCURACIES OF  o MS IN WIND SPEED AND  on IN DIRECTION  )N ADDITION TO OPEN OCEAN OBSERVATIONS  CALIBRATED DATA FROM THIS CLASS OF 3"2 HAVE BEEN APPLIED TO A VARIETY OF LARGE 
  AND PITCH 
 At an angle  4, the contribution from a particular point on the aperture will be advanced or retarded in  phase by 2n(z/12) sin 4 radians. Each of these contributions is weighted by the factor A(z). The  field intensity is the integral of these individual contributions across the face of the aperture. 
 The single input cavity can be made to tune over the entire band  with low VSWR. Thus, the constant efficiency amplifier is a grid-controlled tube, operating as class- AB, that consists of an inductive-output tube with a multistage depressed collector. It  is a linear amplifier whose prime power can be proportional to the output power, pro - viding constant efficiency over a wide range of output powers. 
 ,,",Ê, 
 TION RANGE OF (& OVER MICROWAVE   D" EXTRA RANGE LOSS ACCUMULATES 4HIS CANNOT ALL BE RECOVERED BY RADIATING MORE POWER AND INCREASING ANTENNA GAIN  FOR PRACTICAL ENGINEERING REASONS AND COST  APART FROM CONSTRAINTS IMPOSED BY IONOSPHERIC PROPA 
 The symmetrical C-sandwich can be thought  of as two back-to-back A-sandwiches. This configuration is used when the ordinary  A-sandwich will not provide sufficient strength, or for certain electrical performance  characteristics, or when one layer is to serve as a warm-air duct for deicing. Multiple-Layer Sandwich . 
 (10.24) once p(y1SN) has  been evaluated. If the received waveform y(t) as a function of time consists of the signal  waveform si(t) plus the white gaussian noise waveform n(t) = y(t) - st((), Woodward and  Da~ies~~ show that  where pn[n(t)] = probability-density function for noise waveform n(t) and No = mean noise  power per unit bandwidth (dimensions of energy). With this substitution, the a posteriori  probability for the signal si(t) becomes  The integral in this expression is a definite one, with limits defined by the duration of the  observation time (0 -, To). 
 41. D. Giuli, “Polarization diversity in radars,” Proc. 
 The indicator/receiver was based on a Pye television receiver and is shown in ﬁgure 2.2. The receiver was a superhet with a 45 Mc/s IF. As the U-boat campaign intensi ﬁed, the need to undertake experiments to determine the ability of ASV to detect submarines became urgent. 
 BAND DISH IS  M IN DIAMETER 4HE PEAK TRANSMITTED POWER  &)'52%     .EXRAD  REFLECTIVITY  DATA  FROM  &REDERICK   /KLAHOMA  RADAR ON !PRIL     SHOWING LINE OF INTENSE CON 
 Because amonopulse radarisnotdegraded byamplitude fluctuations, itislesssuscep­ tibletohostileelectronic countermeasures thanisconicalscan. Inbrief.themonopulse radaristhebettertracking technique; butinmanyapplications wheretheultimate inperformance isnotneeded,theconical-scan radarisusedbecause itis lesscostlyandlesscomplex. 5.10TRACKING WITHSURVEILLANCE RADAR Thetrackofatargetcanbedetermined withasurveillan~ radarfromthecoordinates ofthe targetasmeasured fromscantoscan.Thequalityofsuchatrackwilldependonthetime between observations, thelocation accuracy ofeachobservation, andthenumber ofextra­ neoustargetsthatmighthepresentinthevicinityofthetrackedtarget.Asurveillance radarthat develops tracksontargetsithasdetected issometimes calledatrack-while-scan (TWS)radar. 
 520 INTRODUCTION TO RADAR SYSTEMS  equal to the one-way pattern of the conventional antenna of the same length, but with one-half  the beamwidth. The two-way patterns with uniform weighting, assuming small angles, are  approximately  sin [2n(Le/A) sin 01 SAR -+ sin2 [lr(L/I) sin 81  2n(Le/A) sin 8 real array 4 [n(L/A) sin el2  Thus the two-way beamwidth of the SAR antenna is narrower than a real radar antenna of the  same aperture size (if it could be built), but the sidelobes are not as low and do not drop off  with increasing angle as fast. Two-way sidelobes of 13.2 dB in the SAR are not satisfactory for  most purposes. 
 Bamler, “Optimum look weighting for burst-mode and scanSAR processing,” IEEE  Transactions on Geoscience and Remote Sensing , vol. 33, pp. 722–725, 1995. 
 Trizna, “Tests of remote skywave measure - ment of ocean surface conditions,” Proc. IEEE, vol. 62, pp. 
 CODED IMAGE INTENSITY OF A PLANE  X  Z OR  Y  Z  OF SCAN WHEREAS A # 
 Both instruments operate at Ku band (13.4 kHz),  radiating 110 W, 1.5 ms pulses at 190 Hz PRF, split equally between the two antenna  beams. The transmitter is a TWTA, based on NSCAT heritage. The modulated pulse  bandwidth is 40 kHz, which is maintained within an 80 kHz filter in the receiver. 
 R. H. Fletcher and D. 
 of a° for a saturated sea is -27 dB in the upwind or downwind direction (longi- tudinal sea) and is -39 dB in the crosswind direction (transverse sea).23 Figure 24.3 gives the nominal shape of the scattering coefficient for these two condi- tions. The statements so far have all related to vertical polarization, which will have the largest scattering coefficient. Sky-wave radar resolution cell sizes are generally large enough that Faraday rotation can be expected to cause illumina- tion of a resolution cell to be over all polarization angles and consequently to re- duce the average value of a° by 3 or 4 dB, depending on the elevation radiation angle. 
 47. pp. 381 396. 
 On Figure 4.34. Detection range versus height for ASV Mks III and VI against the radar training buoy and Lundy Island [ 9].Airborne Maritime Surveillance Radar, Volume 1 4-28. making a contact, the pilot would turn the aircraft to place the target dead ahead. 
 R. Schimke, “Large-amplitude internal waves observed off the northwest coast  of Sumatra,” J. Geophys. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 precept that efficiency is of low importance for HF reception because external noise  is almost always far stronger than internal noise. 
 Angle ^ 1 deg.- = NoiseAPR SSN = 100 TIME = 8 GMTLOCATION 38.65 N LAT 76.53 W LON BEARING= 90.00 DEGAPRSSN= 1OTIME= SGMTLOCATION 38.65 N LAT 76.53 W LON BEARING= 90.00 OEG Ground Range (nmi) (b) FIG. 24.21 Radar performance estimate; April, 0800 UTC. (a) SSN = 10. 
 SERVICE POINT 
 6.6~  The power output, anode voltage, and efficiency are plotted as a function of the magnetron input  power for a fixed frequency and with the magnetron waveguide-load matched. The peak  voltage is seen to vary only slightly with a change in input power, but the power output varies  almost linearly. Figure 6.6h plots the power output and voltage as the tube is tuned througtt itb  frequency range, when the current is held constant and the waveguide load is matclled. 
 LEM  !LTHOUGH THIS ADAPTATION OF A TWO 
 A P-13, pp. 188-202,  March, 1965.  105. 
 124. Sensors 2019 ,19, 252   Figure 7. Transmitting antenna module block diagram. 
 As shown in Figure 5a, we choose SNR = 20 dB to illustrate the result of adding noise to the RCS curve. The percentage error for aspect entropy calculation in different SNR is shown in Figure 5b. For a certain anisotropic target, the higher the SNR is, the less the error is. 
 In addition to this database, bistatic reflectivity measurements have been made at optical118 and sonic119 wavelengths and of buildings,120 airport structures, and planetary surfaces.66'122 In each of these measurements, the reflectivity data is expressed in terms of reflected power, not afl°.103 The bistatic angle is calculated from the angles in Fig. 25.9 by the use of di- rection cosines: P= cos"1 (sin 0/ sin 6.5 - cos O/ cos 95 cos <|>) (25.19) . *Mcasurcd and interpolated data ranges.TABLE 25.2 Summary of Measurement Programs for Bistatic Scattering Coefficient, <j#° Measurement angles (degrees) *e, e, Polarization FrequencySurface composition Author OrganizationReference (date) 0-145, O, 180 0-1805-30, 5-90 5-905-30, 10-70 5-70W, HH, HV W, HH9 HV10 GHz 10 GHzSmooth sand 1 Loam > Soybeans J Rough sand j Loam with I stubble I Grass JCost, PeakeOhio State University (Antenna Laboratory)42 (1965) 180 18010-90 12-450.2-3 1-8W, VH HHC band X bandSea (sea states 1, 2, 3) Sea (Beaufort, wind 5)Pidgeon Johns Hopkins University (APL)43 (1966) 107 (1967) 180, 165 180, 165 180, 1656-180* ~ 0-180*76-90* ~ 0-90* ~ OW, HH W, HH W, HHX band X band X bandRural land 1 Urban land I Sea (20-kn wind)] Sea (20-kn wind) SemidesertDomville GEC (Electronics) Ltd., England108 (1967) 109 (1968) 110(1969) 0-180 0-1055, 10, 20 5, 10, 2010,40 10, 15, 20HH, HV HH, HV1.3 and 9.4 GHzGrass with cement taxiway Weeds and scrub treesLarson, HeimillerUniversity of Mich- igan (ERIM)111 (1977) 112(1978) 90-160 ~0 ~0 W, HH 9.38 GHzSea(0.9-m, 1.2-1.8-m waveheights)Ewell, ZehnerGeorgia Institute of Technology (EES)113(1982) 114(1984) 0-170 0-170 0-9024 30 10-9024 30 30W, HH VH, HV W, HH VH, HV35GHz 35 GHzVisually smooth sand Visually smooth \ sand I Rough sand | Gravel JUlaby et al.University of Michigan (Depart- ment of Electrical Engineering and Computer Science)115 (1988) . 
 The accuracy may be  quite high (i.e., a few millimeters) for the surface-wearing course, but will reduce to  centimeters at depths of one meter.FIGURE 21.34  Radar profiles along the centerline on Finsterwalderbreen glacier at  320–370 MHz ( from Hamran et al., 2000 ) 0 1000 2000 3000 Distance [m]Depth [m]0 50 100 150 200 250 FIGURE 21.35  Radar images using 1.5 GHz pulse duration along an 8-m long transversal  trace close to a joint of a highway concrete deck. Top: Polarization parallel to the dowels; bottom:  Polarization perpendicular to the dowels. ( Courtesy IEE) Position in m Position in mBackface of concreteDowels JointsTime in ns Time in nsBOE_ _009.DATBOE_ _006.DAT 0 0 1 2 3 40 1 2 3 4 1 2 3 4 5 6 70 1 2 3 4 5 6 7 0.00 0.06 0.12 0.18 0.24 0.00 0.06 0.12 0.18 0.24 0.300.30 Depth in m Depth in m ch21.indd   38 12/17/07   2:51:50 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 MITTER POWER SUPPLY VARIES PULSE TO PULSE  THE TRANSMITTED PULSES WILL NOT BE IDENTI 
 6.22) bymeans ofahorn feed (Chap. 9). Although side. 
 Thisisthefunction oftheduplexer. Theduplexer alsoservestochannel the returned echosignalstothereceiverandnottothetransmitter. Theduplexer mightconsistof twogas-discharge devices. 
 TIONS  BUT ONLY ONE LOCAL OSCILLATOR IS NEEDED  AS OPPOSED TO HUNDREDS OF RECEIVERS 7HICHEVER DESIGN PATH IS FOLLOWED  THE DEMANDS ON RECEIVER LINEARITY AND SPURIOUS 
 LINEAR WITH THE LOCAL VERTICAL #ONVERSION BETWEEN A NORTH COORDINATE SYSTEM AND AN X 
 The returned waves will be reduced inamplitude byafactor awhich depends onthe target and various geometrical factors, asdiscussed inChaps. 2and 3. This returned wave will give rise tocurrents and voltages inthe antenna, which add tothose produced bythe power source and sogive rise toavoltage-current ratio, orimpedance, which ischanged from the value existing ~vhen notarget ispresent. 
 Óx°£n  2!$!2 (!.$"//+  A RECEIVER AND !$# ARE BEHIND EVERY ELEMENT )N THIS SYSTEM  THE TIME DELAY IS IMPLE 
 TIME ADAPTIVE PROCESSING FOR AIRBORNE RADAR v -)4 ,INCOLN ,ABORATORY 2EPORT    APPROVED FOR UNLIMITED PUBLIC DISTRIBUTION   . - 'REENBLATT  * 6 6IRTS  AND - & 0HILLIPS  h& 
 ASV Mk. XIIIB was intended for forward search, using scanner type 80 (re ﬂector size 24 ″×16″) which was stabilised against aircraft roll. In 1945 it was intended that ASV Mk. 
 45 Sampling receiver, 21.23 SAR-Lupe radar, 18.13 to 18.14 SARTs (Search and Rescue Transponders), 22.27 SAW delay line for pulse compression, 8.10 to 8.11 Scan compensation, and platform motion, 3.18 to 3.21 Scan SAR, 18.12 to 18.13, 18.24 Scatterer, 14.4 Scatterometers, 16.19 to 16.24, 16.26 to 16.28 space based, 18. 53 to 18.58 table of, 18.56 wind measurement, 18.54 to 18.55 Sea clutter Bragg scatter, 15.28 to 15.32, 15.38 breaking waves, 15.6 to 15.7 composite-surf ace model, 15.30 to 15.32 contaminants, effect of, 15.26 to 15.27 and ducti ng, 15.24 to 15.25 empirical behavior of, 15.7 to 15.27 as a global boundary-value problem, 15.27 to 15.32 at HF, 15.19, 20.30 to 20.33 at high grazing angles, 15.16 at low grazing angles, 15.16 to 15.18 at millimeter waves, 15.20 numerical methods for, 15.36 rain, effect of, 15.23 to 15.24 sea spikes, 15.2, 15.16 to 15.17, 15.35 shadowing, effect of, 15.25 sigma zero definition, 15.7. spectrum, 15.20 to 15.23 statistics, 15.8 to 15.9 surface currents, effect of, 15.25 to 15.26 surface features, 15.33 to 15.34 theories of, 15.27 to 15.37 wind speed and direction, 15.12 to 15.16 Sea descriptors, general, 15.5 to 15.6 Sea echo. 
 In practice, therefore, the threshold level  would probably be adjusted slightly above that computed by Eq. (2.26), so that instabilities  which lower the threshold slightly will not cause a flood of false alarms.  If the receiver were turned off (gated) for a fraction of time (as in a tracking radar with a  servo-controlled range gate or a radar which turns off the receiver during the time of transmis-  sion), the false-alarm probability will be increased by the fraction of time the receiver is not  operative assuming that the average false-alarm time remains the same. 
 This property can be used as a possible basis for discriminating one target from another. For  example, a thin straight wire can be readily distinguished from a homogeneous sphere by  observing the variation of the echo signal amplitude as the polarization is rotated. The echo  from the sphere will be unmodulated, and the echo signal from the wire will vary between a  maximum and a minimum at twice the rate at which the polarization is rotated. 
 6.30 gives the image component  due to time-delay imbalance in the I and Q paths. Small time-delay imbalances can  be corrected by adding time delay to the A/D sample clock, as shown in Figure 6.13.  Large time-delay corrections should be avoided as they can cause problems aligning  the I and Q digital data. 
 12. Garmatyuk, D.; Narayanan, R. Ultra-wideband continuous-wave random noise arc-SAR. 
 104-109, November, 1945; pt. 2, vol. \8, pp. 
 RABLE BANDWIDTHS WHEN THE TUBE PRODUCES HIGH POWER 4HE PERFORMANCE OF A 474 IS SIMILAR TO THAT OF A WIDEBAND KLYSTRON  EXCEPT THAT IT MIGHT NOT BE AS STABLE AS THE KLYSTRON AND HAVE SLIGHTLY LESS GAIN 4HE MICROWAVE POWER MODULE -0-    WHICH IS A COMBINA 
 36, pp. 132–149, January 2000. 139. 
 Apr 17. 1959.  126. 
 Gallium arsenide field-effect transistors (GaAsFET)haveals,?been considered atthehighermicrowave frequencies. Boththetransistor andthediodemicrowave generators arecharacterized bylowpower,ascompared withthepowercapahilities ofthe microwave tubesdiscussed previously inthischapter. Thelowpower,aswellasothercharac­ teristics, maketheapplication ofsolid-staie devicestoradarsystems quitedifferent from high-power microwave tubes.Thealmosttotalreplacement ofreceiver-type vacuum tuhesby solid-state devicesin~lectronic systems hasofferedencouragement forreplacing thepower vacuum tubewith'anallsolid-state transmitter toobtaintheadvantages offeredbythat ~, I. 
 355–381, 463–465, 431–437. 53. J. 
 SALLY USEFUL ACROSS ALL THE COMMON RADAR BANDS FROM 5(& THROUGH 7 BAND )N FACT  AMONG THE RADAR BANDS  THERE IS OFTEN A DIFFERENT DOMINANT DEVICE TYPE  ALONG WITH ITS ATTENDANT DESIGN AND FABRICATION METHODOLOGIES   THAT OFFERS THE OPTIMUM PERFORMANCE  FOR THAT BAND ! FIRST ORDER APPROXIMATION  OF THE POWER OUTPUT FROM A SINGLE 
 9  Printed in Singapore . CONTENTS  Preface ix  I The Nature of Radar  l. I Introduction 1  t.2 The Simple Form of the Radar Equation J  t.J Radar Block Diagram and Operation 5  1.4 Radar Frequencies 7  1.5 Radar Development Prior to World War II 8  1.6 Applications of Radar 12  Rercrences 14  2 The Radar Equation 15  2.1 Prediction of Range Performance 15  2.2 Minimum Detectable Signal 16  2.3 Receiver Noise 18  2.4 Probability-density Functions 20  2.5 Signal-to-noise Ratio 23  2.6 Integration of Radar Pulses 29  2.7 Radar Cross Section of Targets 33  2.8 Cross-section Fluctuations 46  2.9 Transmitter Power 52  2.10 Pulse Repetition Frequency and Range Ambiguities 53  2.11 Antenna Parameters 54  2.12 System Losses 56  2.1 J Propagation Effects 62  2.14 Other Considerations 62  References 65  3 CW and Frequency-Modulated Radar 68  .ll The Doppler Effect 68  3.2 CW Radar 70  JJ Frequency-modulated CW Radar 81 . 
 ING  AND THIS MODEL HAS BEEN WIDELY ACCEPTED AS BEING THE MOST ACCURATE FOR RADAR PERFORMANCE PREDICTIONS    
 The  weights to be applied can be computed by Eq. 24.3. The capability to cancel a certain  number of main-beam interferences depends on the available number of high gain  beams. 
 31.Vadus.J.R.:ANewTactical Radar,Ordnance. vol.49,pp.80-83.July-Aug., 1964. 32.Rrown.B.P.:RadarHeightFinding. 
 Dwork, B. M.: Detection of a Pulse Superimposed on Fluctuation Noise, Proc. IRE, vol. 
 Itisnow possible toroll upplates and reflector strip insuch away that the feed path isannular. This type ofrollisordinarily simpler tobuild than the one described inSec. 9“15. 
 The beamwidth has been taken to be 5.7° and the surface scattering coefficient to be -35 dB, and with a 12 dB path enhancement the clutter level has been plotted. The clutter-to-noise ratio (CNR) at 1000 nmi is about 82 dB. For the constant beamwidth assumed, the clutter-to-signal ratio increases with range and is 47 dB at 1000 nmi. 
 £È°ÈÓ  2!$!2 (!.$"//+   4 * 3CHMUGGE  h%FFECT OF TEXTURE ON MICROWAVE EMISSION FROM SOILS v  )%%% 4RANS  VOL '% 
 BANDWIDTH CORRECTION SIGNAL "ECAUSE OF THE NOISY NATURE OF THE CLUTTER SIGNAL  THE NEED TO HAVE THE CONTROL SYSTEM  BRIDGE REGIONS OF WEAK CLUTTER RETURN  AND THE REQUIREMENT NOT  TO RESPOND TO THE DOP 
 The number ofpulses striking thetarget during one scan isanimpor- tant parameter inradar design which will reappear frequently inlater 1The useofdifferent directions ofpokv-ization asan~cans ofdistinguishing one arriving signal from another suggests itself immediately. ‘~his would beaneffective and elegant method fcroperation ontwo channels with common antennas were it notthat radar echoes, ingeneral, aresubstantially depolarized.. SEC. 
 POLARIZED FEED ENERGY 4HE BEAM  POLARIZED PARALLEL TO THE GRID  IS COLLIMATED BY THE PARABOLOID AND IS REFLECTED BY A FLAT MOVEABLE POLARIZATION ROTATING MIRROR 4HE BASIC POLARIZATION ROTATING MIRROR IS A FLAT METAL SURFACE WITH A GRID OF WIRES LOCATED A QUARTER WAVE 
 IEEE 1985 Int. Radar Conf ., Arlington (VA), USA, May 6–9, 1985,  pp. 292–296. 
 Pierson et al., “The effect of coupling on monostatic-bistatic equivalence,” Proc. IEEE ,  pp. 84–86, January 1971. 
 NUMBER OF PULSES FIG. 2.7 Required signal-to-noise ratio (detectability factor) as a function of number of pulses noncoherently integrated, square-law detector, Swerling Case 1 fluctuating target, and 0.9 probability of detection. (From Ref. 
 The usual detection criteria employ the concept of direct probabil­ ity, which describes the chance of an event happening on a given hypothesis. For example, the  probability that a particular radar will detect a certain target under specified conditions is a  direct probability. On the other hand, if an event actually ha:ppens, the problem of forming the  best estimate of the cause of the event is a problem in inverse probability. 
 IET Radar Sonar Navig. 2017 ,11, 1597–1603. [ CrossRef ] 293. 
 Ó£°Î{  2!$!2 (!.$"//+  2EMEMBERING THAT A '02 " 
 BAND MICROWAVE TRANSISTOR THAT IS CAPABLE OF PERHAPS  WATTS 7   AVERAGE POWER CANNOT PROVIDE MUCH MORE  THAN  WATTS OF PEAK P OWER WITHOUT OVER 
 DELAY ADJUSTMENTS"$ & $#*%  ) %    "  !#( '#% %"   ,   ,  +%  ,    '   '     '   ' 
 Zebker, H.; Werner, C.; Rosen, P .; Hensley, S. Accuracy of topographic maps derived from ERS-1 interferometric radar. IEEE T rans. 
 4.7 ASV Mk. VI performance Trials of ASV Mk. VI undertaken by TRE [ 1] in early 1944 gave the performance shown in table 4.1. 
 Inthesamemonth,theCHradar stations began24-hour duty,whichcontinued untiltheendofthewar. TheBritishrealized quiteearlythatground-based searchradarssuchasCHwerenot sufficiently accurate toguidefighteraircrafttoacomplete interception atnightorinbad weather. Consequently, theydeveloped, by1939,anaircraft-interception radar(AI),mounted onanaircraft,forthedetection andinterception ofhostileaircraft.TheAIradaroperated ata frequency of200MHz.Duringthedevelopment oftheAIradaritwasnotedthatradarcould beusedforthedetection ofshipsfromtheairandalsothatthecharacter ofechoesfromthe groundwasdependent onthenatureoftheterrain.Theformerphenomenon wasquickly exploited forthedetection andlocation ofsurfaceshipsandsubmarines. 
      WHERE VPO IS THE PULL 
  , BAND  AIR TRAFFIC  CONTROL RADAR DETECTIONS OVER A Ò 
 , ISAP 2000,  Japan, August 2000. 117. T. 
 Whenthe antcnna pointsintllcdirection oftileplatform velocity(0=0),thedoppler shiftoftileclutter ismaximum, butthewidthofthedoppler spectrum !!tIdisaminimum. Ontheotherhand, whentheantenna isdirected perpendicular tothedirection oftheplatform velocity(0=90°), theclutterdoppler center-frequency iszero,butthespreadismaximum. Thiswidening ofthe clutterspectrum cansetalimitontheimprovement factor. 
 Figure 20.7 is a family of plots giving RCS versus radar frequency for an oblong- shaped conducting body. The straight line marked 90 ° λ/2 dipole gives the RCS of a  resonant, conducting half-wavelength rod, where the rod is parallel with the electric  field. This geometry gives the maximum RCS for the rod. 
 A practical rule of thumb for a properly designed system is that a homing time . FIG. 19.4 Line-of-sight (LOS) motion of intercept. 
 GENERATING CAPABILITY OF SINGLE TRANSISTORS IS SMALL WITH RESPECT TO THE OVERALL PEAK AND AVERAGE POWER REQUIREMENTS OF A RADAR TRANSMITTER  TRANSISTORS ARE USED QUITE EFFECTIVELY BY COMBINING THE OUTPUTS OF MANY IDENTICAL SOLID 
 4.41  High-Voltage Power Supplies  .............................  4.41  5. Solid-State Transmitters   ......................................... 
 CIRCUIT hPATCHESv ORIGINALLY CALLED  #OLLINGS RADIATOR AFTER THEIR INVENTOR   4HE ELEMENT HAS TO BE SMALL  ENOUGH TO FIT IN THE ARRAY GEOMETRY  THEREBY LIMITING THE ELEMENT TO AN AREA OF A LITTLE MORE THAN  K  )N ADDITION  MANY RADIATORS ARE REQUIRED  AND THE RADIATING ELEMENT  SHOULD BE INEXPENSIVE AND RELIABLE AND HAVE IDENTICAL CHARACTERISTICS FROM UNIT TO UNIT "ECAUSE THE IMPEDANCE AND PATTERN OF A RADIATOR IN AN ARRAY ARE DETERMINED PRE 
 25.) S/N (dB) FIG. 8.16 Curves of probability of detection versus signal-to-noise ratio for the cell- averaging CFAR, ratio detectors, log integrator, and binary integrator: Rayleigh, pulse- to-pulse fluctuating target, N - 6, and probability of false alarm = 10~6. (From Ref. 
 It refers to the azimuth direction, showing a (hamming simulated) shape of the antenna beam pattern; bottom left: the range cut of the interpolated focused pulse; bottom right: the azimuth cut of the interpolated focused pulse. 95. Sensors 2019 ,19, 1649 Once the azimuth and range reference functions have been deﬁned, focusing can become simple and can be carried out with either RD or Ω-K algorithms. 
 (2) m. Equation (2)displays thedifficulty ofincreasing the range performance ofaradar setbyraising itspulse power. A16-fold increase inpower is required todouble therange. 
 CODED WAVEFORM 7AVEFORM DURATION  4. S 7AVEFORM BANDWIDTH  ". 
 When the upper two switches are open, the  lower two are closed, and vice versa. Note that in the .. zero" phase state, the phase shift is  generally not zero, but is some residual amount ¢0. 
 This gate isreleased just before, during, orjust after thelocking pulse, while theresonant circuit oftheoscillator isstill ringing. The amplifying circuits that precede the oscillator can bemade reasonably narrow since pulse shape isunimportant. These circuits must bebroad enough to allow forlocal-oscillator detuning and tomaintain alarge locking-pulse- to-noise ratio. 
 TION RESULTING FROM MULTIPATH TRANSMISSION -ULTIPATH EFFECTS CAN SEVERELY DISTORT THE PULSE ENVELOPE  FOR EXAMPLE  BY CREATING A LONG TAIL TO THE PULSE AND EVEN DISPLACING THE POSITION OF THE PEAK 4HE 4O! OF THE PULSE CAN BE TAKEN AS THE INSTANT THAT A THRESHOLD IS CROSSED  BUT IN THE  PRESENCE OF NOISE AND DISTORTION  THIS BECOMES A VARIABLE MEASUREMENT .EVERTHELESS   THE 4O! IS USED FOR DERIVING THE 02) OF THE RADAR 4HE AMPLITUDE OF THE PULSE IS TAKEN AS THE PEAK VALUE $YNAMIC 
 Theoutputofthechannel Bmixeris EB=k2Eacos(±Wdt+¢+~) (3.7) Hthetargetisapproaching (positive doppler), theoutputs fromthetwochannels are E.~(+)=k2Eocos(Welt+c/J)EB(+)=k2Eocos(Wdt+c/J+~) (3.8a) Ontheotherhand,ifthetargetsarereceding (negati\'e doppler), ER(- )=k2Eocos(Wdt-¢-~) Thesignof(l)dandthedirection ofthetarget'smotionmaybedetermined according to whether theoutputofchannel Bleadsorlagstheoutputofchannel A.Onemethod of determining therelativephaserelationship between thetwochannels istoapplytheoutputsto asynchronous two-phase motor.18Thedirection ofmotorrotation isanindication ofthe direction ofthetargetmotion. Electronic methods maybeusedinsteadofasynchronous motortosensetherelative phaseofthetwochannels. Oneapplication ofthistechnique hasbeendescribed forarate-of­ climbmeterforverticaltake-offaircrafttodetermine thevelocityoftheaircraftwithrespectto thegrounddtiringtake-offandlanding.19Ithasalsobeenappliedtothedetection ofmoving targetsinthepresence ofheavyfoliage,20 asdiscussed inSec.13.6. 
 TO 
 TO 
 PULSE SPECTRAL COMPOSITION&)'52%    0OWER AMPLIFIER COMBINING CONFIGURATIONS THAT PROVIDE MINIMUM INPUT PORT  REFLECTED POWER A   QUADRATURE 
 Wang, C.; Zhang, M.; Xu, Z.W.; Chen, C.; Sheng, D.S. Effects of anisotropic ionospheric irregularities on space-Borne SAR imaging. IEEE T rans. 
 PULSE -4) CANCELER   WHICH PROVIDES OPTIMUM PERFORMANCE FOR ALL TARGET DOPPLERS ! MORE ATTRACTIVE APPROACH FOR DESIGNING AN OPTIMUM -4) FILTER IS TO MAXIMIZE  ITS IMPROVEMENT FACTOR OR CLUTTER ATTENUATION  4O DESIGN AN OPTIMUM -4) FILTER USING IMPROVEMENT FACTOR AS THE CRITERION  THE COVARIANCE MATRIX OF THE CLUTTER RETURNS  AS GIVEN BY %Q   IS AGAIN THE STARTING POINT !S SHOWN BY #APON   THE WEIGHTS OF THE OPTI 
 The  propagation code used here is due to Berry and Chrisman,157 and it is quite flexible,  permitting antenna and target altitudes, surface conductivity and permittivity, polariza - tion, and frequency to be specified. The key points to be drawn from this example are  (i) the apparent advantage to be gained by operating at low frequencies where propaga - tion losses are minimized, though this benefit must be balanced against antenna size,  the higher noise environment, and (often) reduced target RCS; and (ii) the rapidly  accelerating fall-off in signal strength at ranges beyond a few hundred kilometers,  where 10 dB of extra transmit power may buy only on the order of 10 kilometers of  additional detection range. A more widely used propagation code is GRWA VE,158 which employs different  mathematical representations for the field, depending on range and other parameters, so  as to maximize computational efficiency. 
 9 Zhonghao Wei, Bingchen Zhang and Yirong Wu Accurate Wide Angle SAR Imaging Based on LS-CS-ResidualReprinted from: Sensors 2019 ,19, 490, doi:10.3390/s19030490 ..................... 27 Yamin Wang, Wei Yang, Jie Chen, Hui Kuang, Wei Liu and Chunsheng Li Azimuth Sidelobes Suppression Using Multi-Azimuth Angle Synthetic Aperture Radar ImagesReprinted from: Sensors 2019 ,19, 2764, doi:10.3390/s19122764 .................... 39 Zhichao Zhou, Yinghe Li, Yan Wang, Linghao Li and T ao Zeng Extended Multiple Aperture Mapdrift-Based Doppler Parameter Estimation and Compensationfor Very-High-Squint Airborne SAR Imaging Reprinted from: Sensors 2019 ,19, 213, doi:10.3390/s19010213 ..................... 
 The element has to be small  enough to fit in the array geometry, thereby limiting the element to an area of a little  more than l2/4. In addition, many radiators are required, and the radiating element  should be inexpensive and reliable and have identical characteristics from unit to unit. Because the impedance and pattern of a radiator in an array are determined pre - dominantly by the array geometry (Section 13.4), the radiating element may be chosen  to suit the feed system and the physical requirements of the antenna. 
 STORMS THAT OCCUR IN THE &RONT 2ANGE OF THE 2OCKIES IN THE SUMMERTIME DEVELOP OVER SUCH hBOUNDARIESv BETWEEN TWO DIFFERENT AIR MASSES 3INCE THESE BOUNDARIES CAN BE DETECTED BEFORE ANY CLOUDS ARE PRESENT AND IT IS POSSIBLE TO INFER THE AIR MASS CONVERGENCE OR COMING TOGETHER OF TWO AIR MASSES  WHERE INSECTS ARE FORCED TO ACCUMULATE ALONG THESE BOUNDARIES BY DOPPLER RADAR MEASUREMENTS  MORE PRECISE PREDICTION OF THUNDERSTORM OCCURRENCE IS POSSIBLE &ROM THE RADAR DESIGNERS STAND 
 POLAR RECEIVED SIGNALS IN EACH POLARIZATION ARE SUFFICIENT FOR THE POLARIMETRIC    MEASUREMENTS )T IS OUR OPINION THAT NO SINGLE TOPIC IN RADAR METEOROLOGY HAS RECEIVED MORE  ATTENTION THAN RAINFALL RATE MEASUREMENT !LTHOUGH USEFUL EMPIRICAL EXPRESSIONS HAVE EVOLVED AND DUAL 
 The sea clutter background does not change significantly during the time  the usual civil-marine radar antenna (with a 20 rpm rotation rate) scans by a particular  clutter patch. That is, the sea can be considered " frozen" during the observatioil time. For a  medium-resolution X-band radar at low grazing angles, the time required for the sea clutter  echo to decorrelate is about 10 ms.l6S2' Any pulses received from sea clutter during this time  will be correlated and no improvement in signal-to-clutter ratio will be obtained by integra-  tion. 
 Experimental measurements,  however, show that Z is related to the rainfall rate r by  where a and h are empirically determined constants. With this relationship tlie rccc~ved cctio  power can be related to rainfall rate. A number of experimenters have attempted to determine  the constants in Eq. 
 The extreme values (minima and  maxima) are moved against each other  because of the differences in the  secondary radiation diagram of the target  for the different carrier frequencies. If the  backscatter of the first frequency has a  maximum, then the back scatter of the  second frequency has a minimum for most  part. The sum of both signals d oesn’t alter  the average of the single signals. 
 Ó°Îä  2!$!2 (!.$"//+  !LSO SHOWN IN &IGURE  IS A HORIZONTAL LINE LABELED hAVERAGE 3#2 IMPROVE 
 3.33  Examples of Phase Detectors  ............................  3.36  Analog-to-Digital Phase Detector  .......................  3.37 . 
 Banks. I). S.: Contirii~ous Wave (CW) Radar, EASCON '75 Record, IEEE Publ. 
 pp. 89-106, A UJ.?USt. 1964. 
 Instead, one has tomake use ofempirical meteorological data correlating drop size (really distribution-in-sizej with precipitation rate toarrive finally atarelation connecting attenuation indecibels :This conclusion holds solong asthediameter ofthedrops isvery much lessthan A/n, where nistheindex ofrefraction ofwater atthefrequent yinquestion.. 62 THERADAR EQUATION [SEC. 215 per kilometer, with precipitation rate inmillimeters per hour. 
 PULSE BASIS OR BY GROUPS  &)'52%   A  2& PHASE 
 Fabrizio, L. Scharf, A. Farina, and M. 
 The principle may bebetter understood byconsidering asimplified antenna which consists ofareflector and parallel trapezoidal plates with a long flared base “illuminating” the reflector; the plates are fed with. 300 ANTENNAS, SCANNERS, ANDSTABILIZATION [SEC. 915 perpendicularly polarized waves byawaveguide atthe small base (Fig. 
 The high permittivity of plants with much moisture means  that radar return from crops varies as the plants mature, even when growth is neglected. FIGURE   16. 3 Measured moisture dependence of the dielectric   constant of corn leaves at 1.5, 5.0, and 8.0 GHz. 
 1282–1285, 1989. 20. G. 
 3.5. The two-frequency CW radar spectrum (and its corre-  sponding waveforni) are not always suitable in practice since they lead to ambiguous measure-  rnents if the frequency separation B between the two sine waves is greater than c/2Rb, where c  is the velocity of propagation and Rb is the maximum unambiguous range. If the range  measurement is to be unambiguous, the spectrum must be continuous over the bandwidth B. 
 ATED POWER  INTEGRATED OVER THE BAND OF INTEREST  MAY BE IN THE ORDER OF A MILLIWATT  BUT THE POWER PER (Z MAY BE AS LOW AS PICOWATTS '02 IS USUALLY OPERATED SO THAT THE TARGET  WHICH IS WITHIN A LOSSY DIELECTRIC  IS  ONLY A FEW WAVELENGTHS FROM THE APERTURE OF ANTENNA 4HE TOTAL PATH LOSSES WITHIN A FEW WAVELENGTHS MAY REACH  D" OR MORE DEPENDING ON THE MATERIAL -ANY '02 SYSTEMS OPERATE IN A REGION  WHERE THE WAVELENGTHS RADIATED ARE  GREATER OR IN THE SAME  ORDER OF MAGNITUDE AS THE TARGET DIMENSIONS 4HUS  '02 OPERATES BETWEEN THE 2AYLEIGH REGION AND -IE OR RESONANCE REGION OF THE TARGET DIMENSIONS 4HIS IS VERY DIFFERENT FROM CONVENTIONAL RADAR SYSTEMS WHERE THE TARGET DIMENSIONS ARE MUCH LARGER THAN THE WAVELENGTH OF THE INCIDENT RADIATION  IE  THE OPTICAL REGION 4HE TECHNOLOGY OF '02 IS LARGELY APPLICATIONS 
 5. Davenport. W. 
 Figure 2.8 shows the additional processing required to generate centroided  Target Reports and the processing of these Target Reports to obtain track outputs for  display to the air traffic control system. The MTD radar transmits a group of N pulses at a constant pulse repetition fre - quency (PRF) and at a fixed radar frequency. This set of pulses is usually referred  to as the coherent processing interval (CPI)  or pulse batch. 
 As the radar energy  propagates through the rain, the differential phase shift and the differential attenuation results  in the circular polarization being converted to elliptical polarization. By selecting the optimum  elliptical polarization, it has been said that the cancellation in some regions of" heavy rain"  might be increased by as much as 12 dB over that obtained with circular polarization.81  However, the polarization that is optimum for one particular region might actually prove to  be worse than the cancellation obtained with circular polarization in some other region. The  optimum polarization thus depends on the distance traveled in rain, so that the antenna  polarization needs to be continuously adjusted. 
   &)'52%  A  4HREE 
 vol. AP-24. pp. 
 Conditions are approximately standard inwinter. Ducting in the central Mediterranean area is caused by the ﬂow ofwarm, dry air from the south, which moves across the sea and thus providesan excellent opportunity for the formation of ducts. In winter, however, theclimate in the central Mediterranean is more or less the same as Atlanticconditions, therefore not favorable for duct formation. 
 91. R. Fabrizio, “A high speed digital processor for realtime SAR imaging,” in IGARSS 1987 , Ann  Arbor MI, vol. 
 J. W. Wright, “A new model for sea clutter,” IEEE Trans ., vol. 
 This procedure ispossible becauseofthelinearity oftheFourier-transform thatrelatestheaperture illumination andtheradiated patterntAnexample9oftheeffectofaperture blocking causedby thefeedinaparaboloid-reflector antenna isshowninFig.7.5.Buildings inthevicinityof ground-based radar,andmastsandotherobstructions inthevicinityofshipboard antennas canalsodegrade theradiation patternbecauseofaperture blocking.131 -20,...-25 1'\ I\ I \ I\ I \ ~"-30 I \I\II , \ f\III-35 ," -15-10-5 0 5 Degreesoffaxis1520Figure7.5Effeclofaperlureblock­ ingcausedbythefeedinapara­ bolic-reflector antenna. (Fromc. Cutler,9 Proc.IRE.). 
  
 49. D. Massonnet and K. 
 With a very long focal length, the space  feed approximates a parallel feed. With a very short focal length it approximates a  ch13.indd   41 12/17/07   2:40:50 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The accuracy of this estimator is given  in Figure 7.7 for the case of n = 2 pulses per beamwidth. This estimation procedure  can also be used to estimate the elevation angle of a target in multibeam systems where  q1 and q2 are the elevation-pointing angles of adjacent beams and A1 and A2 are the  corresponding amplitudes. Binary Integrator . 
 3. D. C. 
 There­ fore.whenadditional isolation isnecessary, asinthehigh-power CWtracker-illuminator, a dynamic canceler canhelIsedthatsensestheproperphaseandamplitude required ofthe nullingsignal. 5.1JDynamic cancelation oftheleakage bythistypeof"feedthrougl1 nulling" canexceed.10dB.,'I Thetransmitter signalisneverapureCWwaveform. Minutevariations inamplitude (AM)andphase(FM)canresultinsideband components thatfallwithinthedoppler frequency band.Thesecangenerate falsetargetsormaskthedesiredsignals,Therefore both AMandFMmodulations canresultinundesired sidebands. 
 Asaresult, ifnocorrective measures were taken, each individual sweep onthe display tube would bedisplaced inthe negative direction byafixed amount and the10CUS ofthesweep origins would bea“nega- tive” circle. This difficult yhasbeen overcome bytwo general methods, each ofwhich has variations most suitable toparticular circumstances.. 536 THE RECEIVING SYSTEM—INDICATORS [SEC. 
 ( after G.V . Trunk and J.D. Wilson80 © IEEE 1987 ) FIGURE 7.45  Association probabilities for experimental data. 
 It predates the  widespread use of the term probability of detection and came about by the manner in which  the performance of ground-based search-radars was checked. An aircraft would be flown on a  radial course and on each scan of the antenna it would be recorded whether or not a target blip  had been detected on the radar display. This was repeated many times until sufficient data was  obtained to compute, as a funct_ig1J of r<!_11ge, the ratio of the average num~er of scans the target  was seen al a particular range (blips) to the total number of times it could have been seen  (scans). 
 The calibrated signal may be fed through the  receiver at a time when the transmitter is off. Figure 16.12 b shows a similar arrange - ment in which the signal from the transmitter is attenuated a known amount and used to  check the receiver gain. By comparing the output from the attenuated transmitter signal  with that received from the ground, the scattering cross section may be determined  without actually knowing the transmitted power and the receiver gain. 
 In principle, any of the Jn components of the difference-frequency signal can be extracted  ill the FM-CW radar. Consider first tlie d-c term J,(D) cos (2?fd t - $O). This is a cosine wave  at tile doppler freque~~cy with an arliplitude proportional to Jo(L)). 
 Yuen, “X band microwave scattering from ocean waves,”   J. Geophys. Res ., vol. 
  
 9. J. A. 
 53, pp. 1012–1015,  1965. 60. 
 10.3 LINEARFM The linear-FM, or chirp, waveform is the easiest to generate. The compressed- pulse shape and SNR are fairly insensitive to doppler shifts. Because of its great popularity, more approaches for generating and processing linear FM have been developed than for any other coded waveform.1 The major disadvantages are that (1) it has excessive range-doppler cross coupling which introduces errors unless either range or doppler is known or can be determined (i.e., a shift in doppler causes an apparent change in range and vice versa); and (2) weighting is usually required to reduce the time sidelobes of the compressed pulse to an acceptable level. 
 In the monostatic  case, doppler spreading is  (∆fd)m = [2ar / l]1/2 (23.3) where ar is the radial component of target acceleration. Equation 23.3 also applies  to the bistatic case at small bistatic angles, b, particularly in an over-the-shoulder   operation, where the target lies near the baseline extended beyond either the receiver  or the transmitter (called the extended baseline ).* However, for larger b—the general  case—the radial component, which is aligned with the bisector of the bistatic angle,  will be reduced. A rule of thumb for these large b conditions is  (∆fd)b = [ar / l]1/2 (23.4) Equation 23.4 is used to set to and hence the noise bandwidth of receiver’s predetec - tion filter Bn. 
 20.14  Spherical Earth: Exac t Geometry  .......................  20.14  Corrections for Atmospheric Refraction  ..............  20.15 Practical Corrections  .......................................... 
 IN PERFORMANCE MONITORING AND FAULT ISOLATION  HIGH RELIABILITY  AND WORLDWIDE INVEST 
 These low-jitter timing  signals are used to enable and disable the transmit power amplifier to create the trans - mit pulse train, blank the receiver during transmission, and form the range gates. Reference Generator.  The reference generator outputs fixed frequency clocks and  local oscillators (LOs). 
 LOOP TRACKING TO ALIGN ITS ANTENNA AXIS AT A POINT MANY TIMES THE SCATTERER SPACING AWAY FROM THE SCATTERERS )F THE SCATTERERS ARE STATIONARY  THE RADAR ANTENNA WILL STAY POINTING IN THE ERRONEOUS DIRECTION &IGURE  SHOWS EXPERIMENTAL DATA DEMONSTRATING THIS PHENOMENON WITH A TWO 
 (7.3 1).  RADAR ANTENNAS 263 whereGoisthegainortheantenna intheabsenceoferrors,and1Jisthephaseerror,inradians, calculated fromthemeanphaseplane.Thissimpleexpression isvalidforanyapertureiIJumin­ ationandreflector deformation. provided thatthelatterissmallcompared tothewavelength. 
 RADIUS OF   KILOMETERS AND A REFRACTIVITY GRADIENT OF n .KM GIVES A  K OF  OR ABOUT  )N ADDITION TO THE CONSIDERATION OF REFRACTION  OTHER STANDARD  PROPAGATION MECH 
 OROLOGICAL PARAMETERS  3PACED !NTENNA 4ECHNIQUES   !N ADDITIONAL ADVANTAGE OF THESE LONG WAVELENGTH  RADARS IS THEIR ABILITY TO MEASURE NOT ONLY THE RADIAL VERTICAL WIND COMPONENTS DIRECTLY  BUT ALSO THE MEAN HORIZONTAL WIND THAT IS TRANSVERSE TO THE VERTICAL BEAM WITHOUT SCANNING THAT BEAM OFF ZENITH 4HESE PROFILERS USE THE SO 
 Beyond that, the RCS curve denoising greatly enhances the discrimination capabilities of aspect entropy. T able 2. The aspect entropy of targets. 
 The signal received on  the difference pattern is weighted by the factor k, shifted in phase by 90" and is added to the  sum-pattern signal in the delayed channel and subtracted from the sum-pattern signal in the  undelayed channel. Because of the phase relationships between the lobes of the difference  pattern and the sum pattern, the result is an apparent forward displacement of the pattern on  the first transmission, and a displacement to the rear on the second transmission. Wlicn tt~c  gains of the sum and difference channels are properly adjusted, and when the distance between  the phase centers of the two antenna beams is 2Tpvx the combined sum and diKerence patterns  on successive pulses illuminate the same region and the antenna appears sta~ionary.~' (The  f:~ctor 2 appears in the distance between phase centers. 
 If the display can be off-centered, this may permitdisplay of the targets on a shorter range scale than would be possible otherwise.Pulse Length (microseconds)Range Resolution (yards) 0.05 8 0.10 160.20 330.25 410.5 821.2 197 Figure 1.20 - Receiver gain and range resolution. CRT Diameter (Inches)Range Scale (nautical mi.)Spot Length or Width (yards) Nominal Effective 9 7.5 0.5 5 24 220 12 10.5 0.5 4 24 185 16 14.4 0.5 3 24 134. 29FACTORS AFFECTING BEARING ACCURACY Horizontal Beam Width Bearing measurements can be made more accurately with the narrower horizontal beam widths. 
 IEEE Geosci. Remote Sens. Lett. 
 ANE-11, pp. 162–172, September 1964 and reprinted in D. K. 
 The jammer noise power per hertz  at the radar is  where .4,. = crPtctivc receiving aperture of tlie radar antenna and R = range of jammer from  radar. Substituting Eq. 
 LOGO FR J     WHERE F   INPUT SIGNAL FREQUENCY  RJ   RMS APERTURE JITTER 3IMILARLY  CLOSE 
 C. Williams and M. E. 
 TRAFFIC CONTROL RADARS -ICROWAVE 0OWER -ODULE -0-    ! NOVEL VARIANT OF THE LINEAR 
 Conv. Record, vol. 6,  pt. 
 E. Kerr (ed.), MIT Radiation  Laboratory Series, Chap. 6, V ol. 
 REFERENCES 1.Goldman, S.:"Frequency Analysis, Modulation, andNoise,"p.281,McGraw-Hili BookCompany, NewYork,1948. 2.Torrieri, D.J.:ArrivalTimeEstimation byAdaptive Thresholding, IEEETrans.,vol.AES-I0. pp. 
 KM SWATHS  TO 3POT3!2  
 The sun also can be used  as a source to calibrate the beam-pointing (boresight) of large antennas.58 Discrete radio  sources, call&l radio stars, are too weak at radar frequencies to be a serious source of interfer­ ence, but they have been used in conjunction with sensitive receivers to determine pointing and  focusing corrections for large antennas.59  System noise temperature. Figure 12.12 illustrates some of the sources of noise which generally  must be considered when computing the system effective noise temperature. The antenna sees  the cosmic noise at a temperature Tc with an intervening absorbing atmosphere at a tempera­ ture T.1 and a Joss L.,. 
 PULSE COMPRESSION RADAR  8.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 Frequency Domain Weighting for LFM Time Sidelobe Reduction.1,2,4 A frequency  domain weighting filter is used following the matched filter for time sidelobe reduction.  Taylor weighting provides a realizable approximation to the ideal Dolph-Chebyshev  weighting, which achieves the minimum mainlobe width for a given value of peak  time sidelobe level. The frequency response of the equivalent low pass filter for the  Taylor weighing filter is  W f Fmf Bm mn ( ) cos = +   =− ∑ 1 2 2 11 π  (8.10) where Fm is the Taylor coefficient and n is the number of terms in the weighting func - tion. 
 MANCE IN TAIL CHASE  WHERE THE TARGET DOPPLER IS IN THE SIDELOBE CLUTTER REGION NEAR THE ALTITUDE 
 FIG. 7.12 Coupled signals to a central element from neighboring elements. pqth element. 
 13.9] ELECTRONIC SWITCHES 509 pulses occurring during agiven time interval. The triode can beused ouly ifboth signals arelimited, since otherwise itcould beturned onby cutoffn(a) *~ndA nL-1 cutoff–--–------ ----- “s’Signal (c)+~ndb% n‘I-# cutoff‘–-–--- ::- ,“,off-* ‘;A,,,C, 4 (b) cutoff +14!4 nGnd‘--–--------- e 6’c7etc. (d) Fm. 
 The pulse fall times are generally very fast, on the order of nanoseconds. However, the rise time for a high-power transistor ampli- fier may be slower, on the order of 100 nanoseconds, and is the result of the re- verse biasing that may be encountered by instantaneous current flow in the emit- ter bias return as the transistor is turning on. This is a design problem for common-base operation, but a common-base configuration is often necessary . 
 Shaping the frequency responsi Nonrecursive filters employ only feedforward loops. If feed­ back loops are used, as well as feedfcirward. loops, each delay line can provide one pole as well  as one zero for increased design flexibility. 
 6.46  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 analog circuitry prior to and within the A/D converter. If the IF filter bandwidth is  wide relative to the digital receiver bandwidth, the majority of the error between  channels will be a constant gain and phase offset across the receiver bandwidth.  A single correction, applied as a complex multiplication of I/Q data, will cor - rect for gain and phase offsets and is usually adequate to provide the required  channel tracking for monopulse applications. 
 DIMENSIONAL POSITION AND  VELOCITY WITH ACCURA 
 Farina, P .; Leoni, L.; Babboni, F.; Coppi, F.; Mayer, L.; Ricci, P . IBIS-M, an innovative radar for monitoring slopes in open-pit mines. In Proceedings of the International Symposium on Rock Slope Stability in Open Pit Mining and Civil Engineering, Vancouver, BC, Canada, 18–21 September 2011. 
 SPREAD FUNCTION IE  DOWNRANGE RESOLUTION     CROSSRANGE RESOLUTION  4HE -4) MODE IS CAPABLE OF DETECTING AND ACCURATELY GEO 
 AIRBORNE MTI  3.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 (1) mechanically scanned with an operator-selectable scan rate, (2) azimuth electroni - cally scanned with the mechanical boresite provided as an input to the radar, and (3)  mechanically scanned with additional electronic scanning within an operator-select - able azimuth region. The transmit waveform includes TACCAR modulation to center mainbeam clutter  at zero doppler frequency. However, because the radar implements adaptive clutter  cancellation (STAP), the requirements on TACCAR are significantly less complex  than for legacy radar systems. 
 31 Note that following the wide-band doppler amplifier is a speed gate,  which is a narrow-band tracking filter that acquires the target's doppler and tracks its chang  ing dorpler frequency shift.  3.3 FREQUENCY-l\'IOOULATEO CW RADAR  The inability of the simple CW radar to measure range is related to the relatively narrow  spectrum (bandwidth) of its transmitted waveform. Some sort of timing mark must be applied  to a CW carrier if range is to be measured. 
 IMPOSED BIPOLAR VIDEO FROM SEVERAL TRANSMITTED PULSES WOULD APPEAR AS IN &IGURE  4HE REMAINDER OF THE BLOCK DIAGRAM IN &IGURE  SHOWS THE REMAINING PROCESS 
 The beam ofacathode-ray tube iscaused tobegin asweep from lefttoright across theface ofthetube attheinstant apulse issent from thetransmitter. The beam isswept totheright atauniform rate bymeans ofasawtooth waveform applied tothehorizontal deflection plates oftheCRT. The output signals oftheradar receiver areapplied tothe vertical deflection plates. 
 DOMAIN CONVOLVER CONSISTS OF A COM 
 Itwill befound todepend onmany other factors, not allreadily accessible tomeasure- ment, ranging from thermal noise inaresistor totheintegrating property oftheeye oftheradar observer. Thus wechoose todivide theproblem into two parts, byafictitious boundary, asitwere, between the radar antenna and the rest ofthe set. The relations which weshall develop inSees. 
 Empirical Filter Design. An example of an empirical filter design for a six- pulse CPI follows. (The six pulses per CPI may be driven by system considerations, such as time on target.) Because the filter will use six pulses, only five zeros are available for the filter design: the number of zeros available is the number of pulses minus one. 
 Rept. 75-76, October 1975. 52. 
 PULL AMPLIFIER #LASS 
 An array is shown in the next figure.     Pre -amplifi - er Configura - tionSoftwareDirect Digital SynthesizerMixer HPA Pre- amplifierDirect Digital SynthesizerMixer HPA   Figure 14.2  Block diagram for SDRS transmit subsystem.     DDSs are now available on the market with frequencies up to almost 1 GH z, more than sufficient  for most applications. 
 This form of CFAR  may not be desirable with MTI since hard limiting reduces the improvement factor or the  clutter attenuation (Sec. 4.8). Hard limiting also introduces an additional loss. 
 Stein and J. J. Jones, “ Modern Communication Principles with Application to Digital  Signaling ,” New York: McGraw-Hill, 1967. 
 The storage isaccomplished intheeye and mind ofthe ohserver and israther astonishingly effective. 1Just howitisdone wedonot know indetail, but wemay seethe results in Fig. 2.5(page 35). 
 1581–1589, 1993. 31. D. 
          !  #& ## 
 Nickel, “Monopulse estimation with sub-array output adaptive beam forming and low side  lobe sum and difference beams,” IEEE Symp. on Phased-Array Systems and Technology , Boston  (MA), USA, October 15–18, 1996, pp. 283–288. 
 Dept. of Commerce. ESSA {\fonograph I. 
 An integrator based on the tapped delay line is shown in  Fig. 10.9. The time delay through the line is made equal to the total integration time, and the  taps are spaced at intervals equal to the pulse-repetition period. 
 SIGHT DIRECTION OF THE RADAR  MAY BE MEA 
 BAND SIGNALS &OR THIS REASON  THE PRIMARY LIMITING STAGE IS USUALLY LOCATED AT THE FINAL )& STAGE WHERE MAXIMUM FILTERING OF OUT 
 As it closes on the target, a fixed angular error at the missile results in a decreas- ing linear error, providing the higher accuracy characteristic of homing guidance. Homing systems can be further categorized on the basis of the source of the sensed radar energy into passive, semiactive, and active. Passive homing uses energy originating from the target (i.e., jamming or radar transmissions). 
   AN EARLY PROTOTYPE OF THE 32 
 IT-14, pp. 349-353,  March, 1968.  59. 
 4(% 
 67. sensors Article Knowledge-Aided Doppler Beam Sharpening Super-Resolution Imaging by Exploiting the SpatialContinuity Information Hongmeng Chen1, Zeyu Wang2, Jing Liu1, Xiaoli Yi1, Hanwei Sun1, Heqiang Mu1, Ming Li3 and Yaobing Lu1,* 1Beijing Institute of Radio Measurement, Beijing 100854, China; chenhongmeng123@163.com (H.C.); jingliu_sp2306@163.com (J.L.); 13466798179@163.com (X.Y.); 13488682636@126.com (H.S.); 13611258792@163.com (H.M.) 2China Academy of Electronics and Information Technology, China Electronic Technology Group Corporation, Beijing 100846, China; beidou13579@163.com 3National Laboratory of Radar Signal Processing, Xidian University, Xi’an 710071, China; liming@xidian.edu.cn *Correspondence: luyaobing65@163.com; Tel.: +86-10-8852-7368 Received: 16 January 2019; Accepted: 11 April 2019; Published: 23 April 2019/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: This paper deals with the problem of high cross-range resolution Doppler beam sharpening (DBS) imaging for airborne wide-area surveillance (WAS) radar under short dwell time situations. A knowledge-aided DBS (KA-DBS) imaging algorithm is proposed. 
 LUTION MIGHT BE VITAL FOR JAMMER MAPPING IN CASE OF MULTIPLE JAMMERS 3UPERRESOLUTION IS ALSO OF INTEREST AS AN %##- TO COUNTER CROSS 
 Low frequency (i.e., closer to the carrier) stability is more applicable  to air-to-ground pulse doppler modes such as GMTI and SAR. The location of an instability source within the system will determine whether it is  imparted upon a return signal via the transmit path, receive path, or both. Instabilities  either on transmit or receive are called independent . 
 Several varieties ofpotentiometer have been made with sine orwith sine and cosine characteristics, foruseasresolvers (Vol. 17). These have been designed with great care and arefairly good atlow turning rates and low signal frequencies. 
 46. Ulaby, F. T., W. 
 11.3), andthephase of thiscomponent canbeadvanced over that oftheother component byanydesired amount, simply bychoosing thewidth ofthesheets along thedirection ofpropagation appropriately. SeeW.E.Kock, ‘‘Metal Plate Lenses forMicrowaves,” BTL Report hlM-45- 160-23. 1ByR,E.Clapp.. 
 . RANGING USED  BY -273 4HESE AMBIGUITY RESOLUTION TECHNIQUES DICTATE HOW THE PROBABILITY OF FALSE ALARM PER RANGE 
 6 th Int. Conf. HF  Radio Systems and Techniques , September 1995, pp. 
 The zero-doppler ref - erence in this figure was located arbitrarily at –116 Hz. The spread along each line   FIGURE 15.15  Short-time averaged doppler spectra at X band for an  intermediate grazing angle of 35°; spectra computed at 0.2 sec intervals  (shallow-water data is from a fixed site on a pier.) ( from W. C. 
 TICAL FEATURES OF CLUTTER AND JAMMER  ARE NOT KNOWN A PRIORI )N FACT  WHEN EITHER THE  JAMMING OR CLUTTER STATISTICS CANNOT BE ESTIMATED INDEPENDENTLY OF ONE ANOTHER  IT BECOMES DIFFICULT TO DESIGN AN EFFECTIVE SPATIAL ADAPTIVE FILTER FOR JAMMING REJECTION OR A TEMPORAL ADAPTIVE FILTER FOR CLUTTER MITIGATION SINCE THE  PRESENCE OF ONE CON 
 Sutherland, J. W.: Marcorii S6(K) Series of Radars, Irtterucia. vol. 
 MC;ISIII.CIIICII~ of LOW ArigIes of Elevation, Pt.oc. 1'11~s. So(. 
 60,  June 1967. 67. W. 
 R. Jensen, C. C. 
 This grating coupling does not have a  significant impact on the surface-wave energy. Except for a 2:1 increase in the waveform  duration, the impulse response of the RAC is the same as for the approaches shown in  Figure 8.7 a and b. Thus, these three approaches yield a similar impulse response. 
 26ofthis series. The circular cylinder shape was early used fortheradome. For such ashape theradiation falls ontheradome essentially atnormal incidence, the angle ofincidence being defined asthe angle between the incident radiation and thenormal tothesurface atthepoint ofincidence. 
 335), the radar picture ofsuch a target isincomparably poorer indetail than avertical photograph taken under favorable conditions would be. One further property ofradar isworth remarking: itsfreedom from difficulties ofperspective, By suitable design ofthe equipment, the picture obtained from aradar setcan bepresented asatrue plan view, 1. SEC. 
 Since a typical . level of purity desired for MTI or pulse compression might be 50 dB, this leads to an isolation requirement of 140 dB from chain output to input. Since typical waveguide joints and coaxial-cable connectors may have leakage levels of the or- der of —60 dB, 140 dB of isolation can be difficult. 
 CURSOR OF THE *ASON ALTIMETERS AND THE 3)2!, INSTRUMENT ABOARD #RYO3AT 4HE 40 ORBIT REPEAT PERIOD WAS CHOSEN CAREFULLY TO SATISFY ADEQUATE OBSERVATION OF  THE DOMINANT ALIASED TIDAL CONSTITUENTS !LL SOLAR TIDAL CONSTITUENTS WOULD BE AMBIGU 
 Thesetwocomponents arecompensated bytwodifferent techniques. AnMTIradaronamovingplatform iscalledAMTI.Although the"A"originally stood forai"bome, thetermisnowoftenappliedtoanMTIradaronanymovingplatform. Mostof theinterestinAMTl,however, isforairborne radar.58 Compensation fordutterdoppler shift.Whentheclutterdoppler frequency isotherthanat dc,thenullofthefrequency response oftheMTIprocessor mustbeshiftedaccordingly. 
  ANTENNA  #OURTESY OF .ORTHROP  'RUMMAN #ORPORATION  .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°ÈÇ )T USES  
 Sutherland, J. W.: Marconi S600 Series of Radars, Interavia, vol. 23, pp. 
 and C.L.; funding acquisition, W.Y. and J.C. Funding: This work was supported by the National Natural Science Foundation of China (NSFC) under Grant No. 
 57. Il)illard. G. 
 44. Rerger, F. R.: The Design of Airborne Doppler Velocity Measuring Systems, IRE Trans., vol. 
 2Inthisdefinition Tiscustomarily, andarbitrarily, taken tobe291“K. SEC.2.9] RECEIVER BANDWIDTH ANDPULSE ENERGY 33 allnoise figure iscomplicated bymany subtle questions which should not now concern us. Byourdefinition thenoise figure Noftheideal system ofFig. 
 CALLED 2AYLEIGH REGION   "Y CONVENTION IN THIS CHAPTER  WE SHALL USE R FOR RANGE AND 2 FOR RAINFALL RATE. £°{  2!$!2 (!.$"//+  7HEN THE RATIO PAL     THE 2AYLEIGH APPROXIMATION MAY BE APPLIED  AND  RI  BECOMES   SP LII+$  \\    WHERE $I IS THE DIAMETER OF THE ITH DROP AND   \\+M M   
 ROUTE TO THEIR WEATHER REGIONS FAR BELOW THE ORBITAL ALTITUDES %QUATION   SHOWS THAT THE RECEIVED POWER IS DIRECTLY PROPORTIONAL TO THE PULSE  LENGTH S 4HE NOISE POWER 0N IS CONVENTIONALLY GIVEN BY   0N   J4"    WHERE J   "OLTZMANNS CONSTANT   r n 7(Z  +   4   RECEIVER NOISE TEMPERATURE  +  "   RECEIVER NOISE BANDWIDTH  (Z &OR A RECEIVER FILTER MATCHED TO THE PULSE LENGTH    "y T    3OMETIMES WEATHER RADARS WILL USE A SHORT PULSE FOR HIGH 02& DOPPLER PROCESSING  AT SHORT RANGES AND A LONGER PULSE AT LOW 02& FOR GREATER SENSITIVITY WHEN PERFORM 
 section ofsuch targets asaircraft orships can beobtained bycalculation. Even ifone could carry through the calculation forthe actual target (usually one hastobecontent with considering anoversimplified model) the comparison ofcalculated and observed cross section would be extremely difficult because ofthe strong dependence ofthecross section onaspect. InFigs. 
 C. Lovell,  Professor P. I. 
 Reed. H. R .. 
 M. King: Phenomena of Scintillation Noise in Radar  Tracking Systems. Proc. 
 AGE INCLUDED A THREE 
 AES-I 1, pp. 768 780, September, l975.  ~. 
 TO 
 SLOPE &- 2ANGING %XAMPLE 4HERE ARE TWO TARGETS  ! AND " &- SLOPE    -(ZS 4ARGET !" 2ANGE NMI    $OPPLER FREQUENCY K(Z   &- SHIFT K(Z      /BSERVED &REQUENCIES F   NO &- K(Z    F  &- UP K(Z    F  &- DOWN K(Z    0OSSIBLE SETS THAT SATISFY THE RELATIONS SHOWN IN %Q  AND %Q  ARE F F F FF   F4ARGET  2ANGE NMI       9ES      .O     .O     9ES . {°ÎÈ  2!$!2 (!.$"//+  SOLUTION IN ORDER TO ENGAGE  AS OPPOSED TO NONTHREATENING TARGETS WHERE A GENERAL SITU 
 III by having a much higher power (200 kW compared with 40 kW) representing an increase in sensitivity of 5 dB. In Figure 7.2. Detection ranges versus height for ASV Mks III and VI for a radar buoy and Lundy island (from [ 2]). 
 AES-13, pp. 11-16, January, 1977.  90. 
 It can be shown that if an array radiates at a particular  angle corresponding to a value min Eq. (8.17b) when the frequency isf, then for some other  value 1111 a beam will be radiated at the same angle when the frequency isf1 =(m1/m)f  Consider, for example an array with spacing d = 0.6J0 and 1/d = 15. This corresponds to  m = f/).0 = 9. 
 The top lines in Figure 15.9 a,b corre - spond to clutter at a grazing angle of 90°, that is, for a radar looking straight down.  On a strictly empirical basis, the clutter cross section at this angle is only weakly  dependent on frequency, has a maximum of about 15 dB at zero wind speed (at  least for the antenna beamwidths and experimental configurations reported), and falls  off gradually as the wind picks up. Scattering at high grazing angles is commonly  regarded as a form of specular scattering from tilted facets of the surface, so it is of  interest to note that there appears to be a small range of angles in the neighborhood  of 80°  for which the cross section is almost completely independent of wind speed. 
 To compare the performance of the three methods in the reconstruction of aspect dependent scattering, we select an aspect dependent scattering target P and plot its aspect dependent amplitude curve Figure 3. The result of BP is used as the reference. In Figure 3, we select Area 1 to show the performance of LS-CS-Residual to reduce the underestimation. 
 D. Tappert, “Application of the split-step Fourier method to the numerical  solution of nonlinear and variable coefficient wave equations,” SIAM Rev., 15, 2, p. 423, 1972. 
 The technical resource was exercised in producing,  under severe difficulties imposed by the wartime need  for stringent secrecy, pulse transmitters of unpre-  cedented power, receivers of unparalleled sensitivity,  aerials of unique design, ancillary equipment of novel  character, all doing somewhat better than before some-  thing previously done after a fashion, some doing things  never done before.  Radar was a direct but not an inevitable fruit of pure  research. On probably no other subject can we say  with so much truth, ‘‘Ifit had not been for the War... 
 When in early summer (May, June, and July) rainfall concentrates, groundwater will be recharged and the rate of subsidence will slow down, see Figure 6. Points B, C, and D show similar trends of subsidence, and point B subsides more than points C and D. The subsidence at point A suddenly increases in 2017 probably due to the construction of Wuhan Metro Line No. 
        
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°ÓÎ WHERE 42 IS THE SLANT  RANGE SWATH DEPTH OF THE ANTENNA PATTERN AND  "$OP IS THE COR 
 P. E. Pace, D. 
 The direction in which the antenna points when the received signal is a maximum indicates the direction of the target. This, as well as other methods for measuring angle, assumes that the atmosphere does not perturb the straight- line propagation of the electromagnetic waves. The direction of the incident waveform can also be determined by measuring the phase difference between two separated receiving antennas, as with an interferometer. 
 HORIZON RADAR v )%%% 4RANS 3IG 0ROC  VOL   PP n    - ' 2UTTEN AND $ * 0ERCIVAL  h*OINT IONOSPHERIC AND TRACK TARGET STATE ESTIMATION FOR MULTIPATH  OTHR TRACK FUSION v  0ROC 30)% #ONF ON 3IGNAL AND $ATA 0ROCESSING OF 3MALL 4ARGETS       PP n  2 ( !NDERSON AND * , +ROLIK  h4RACK ASSOCIATION FOR OVER 
 MAP ANALYSIS THE RESULTS FIT BOTH %ARTH AND LUNAR  RADAR RETURN OVER A WIDER RANGE OF ANGLES THAN THE GAUSSIAN   BUT SOMETIMES NOT  AS WELL NEAR VERTICAL  &URTHERMORE  IT HAS THE MERIT THAT IT EXHIBITS FREQUENCY DEPEN 
 129-133, January, 1958.  36. Provencher, J. 
 The power pattern and the radiation-intensity pattern are  identical when plotted on a relative basis, that is, when the maximilm is normalizz(f to a valt~e  of unity. When plotted on a relative basis both are called the utltetltlu rr~diutiolr putfrrtl.  An example of an antenna radiation pattern for a paraboloid antenna is shown plotted in  Fig. 
  5(&  (IGH !2# 
 With  many switches in parallel, the "off" impedance of each must be high if the combined im­ pedance is to be large compared to the "on" impedance of a single switch. A parallel-line  configuration with 16 lengths of line provides a phase quantization of 22.5° ( ± 11.25°), assum­ ing the nth line is of length 11.A./16. A suitable form of switch is the semiconductor diode. 
 Thegainsarelowormodest, butthe potential existsforhighergains,especially iftrade-offs withotherproperties arepermitted. Reasonably longlifehasbeendemonstrated withCFAs.Operation forgreaterthan10,000 hoursisnotunusual insometubes.l?Thegoodphasestability andshortelectrical lengthof CFAsmakeitpossible tooperate tubesinparalleltoachievegreaterpowerthanavailable fromasingletube,aswellasprovideredundancy intheeventofasingletubefailure.TheCFA behaves asasaturated amplifier ratherthanasalinearamplifier. Thecharacteristic ofa saturated amplifier isthat,aboveacertainlevel,the RFoptputisindependent oftheRFinput. 
 Another interesting effect to be  noted from Fig. 2.7 is that a change of only 3.4 dB can mean the difference between reliable  detection (0.999) and marginal detection (0.50). (When the target cross section fluctuates, the . 
 # CONTINUES IN DEMAND  THANKS TO ITS FULLY POLARIMETRI C MULTIBAND COVERAGE  OF A WIDE VARIETY OF SCENES  4HE 3HUTTLE 2ADAR 4ERRAIN -APPER 324-  WAS AN  OUTGROWTH OF 3)2 
    WHERE  N IS THE NUMBER OF STAGES IN THE  SHIFT 
 23. Kirkpatrick. C;. 
 YEAR LIFE REQUIREMENT. 
 Ufimtsev never attempted to work out his filamentary fringe  currents, but  instead traced their effect directly to the far scattered field. Recognizing that the far-field PO contribution to the far field was the part of the  GTD prescription giving rise to singularities in the X and Y of Eqs. 14.18 and 14.19,  Ufimtsev devised a modified set of diffraction coefficients by simply subtracting away  ch14.indd   25 12/17/07   2:47:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Hogg, D. C., and W. W. 
 Eqiiatioti (8.18) assumed a transtnission line whose velocity of propagation was that of  the velocity of light. It is more usual, however, for transmission lines in a frequency-scan array  to have a velocity of propagation which varies with frequency; i.e., they are dispersive. A  waveguide is an example of a dispersive line. 
 TION 7E TURN OUR ATTENTION TO THE CASE WHERE THE ANTENNA MOVES TO COVER A  SYN 
 Itisalso desirable tobeable tomeasure thedirection inwhich atarget lies asviewed from aradar station. In principle, this can bedone onthe basis oftriangulation, using range information onthesame target from two ormore separate radar locations. Although this method permits ofgreat accuracy and has occasionally been used forspecial purposes, itisfarmore desirable from the stand- point ofsimplicity and flexibility tomeasure direction, aswell asrange, from asingle radar station. 
 The divergence factor accounts for the decay in amplitude as the rays spread away from the edge element and includes the effects of the radius of the edge if it is curved, as at the end of a truncated cylinder, and the radius of curvature of the in- cident phase front.37 The divergence factor for a two-dimensional edge (of infinite length) illuminated by a plane wave is T = l/s. The diffraction coefficients are sin (TfIn)In cos (ir/rt) - cos [(<(>,• - $s)/n] sin (ir/«)/n Y ~ cos (Wn) - cos [(<|>, + <k)//i] (11.23) where <(>, and <$>s are the angles of the planes of incidence and scattering, as mea- sured from one face of the wedge, and n is the exterior wedge angle normalized with respect to TT; see Fig. 11.27. 
 AMPLITUDE FEATURES  LOCALIZED AND NARROW 
 S. Johnson, “Adaptive detection mode with threshold control as a function of  spacially sampled clutter-level estimates,” RCA Rev ., vol. 29, pp. 
 It is possible to pulse some CFAs, which have cold cathodes, to employ what is  called DC operation , where the transmitter is turned on and off to generate a pulse  waveform without the need for a high-power modulator. In dc operation the high volt - age is continuously present between anode and cathode, and the current is turned on  by applying the RF drive and turned off by pulsing the control electrode. (The control  electrode consists of a segment of the cathode structure in the drift region.) To prevent  the tube from starting without RF drive, the cathode must be kept cool enough to pre - vent thermionic emission. 
 IEEE T rans. Geosci. Remote Sens. 
 BAND DIRECTION FINDING  ETC      !LSO  THERE ARE USUALLY SOME CHANNELS AT THE EDGE OF THE ARRAY THAT  ARE PASSIVE AND IMPROVE THE SIDELOBES AND 2#3 PATTERN &IGURE  SHOWS THE COMPARISON BETWEEN A CONVENTIONAL MECHANICALLY SCANNED  RADAR WITH THE LOW 
 N. Khoury and J. S. 
 69-78, 1946.  '3. Saxton. 
 POINT FEED BEHIND IT AND REFLECTIVE TO THE ORTHOGONALLY POLARIZED  + A 
 In additiori to the reduction of jamming noise which enter the airborne surveillance radar,  it is important to reduce the clutter that enters via the radar antenna sidelobes. The detection  of target$ fro111 ;trl airborne platforrn places severe demands on radar design in order to reduce  or elirnirlate clutter that enters the radar receiver via the main beam. This is done ill a  conventional AMTI radar by signal processing (filtering) as described in Sec. 
 Davis, and T. Guella, “Wideband cancellation of multiple mainbeam jammers,”  IEEE Trans ., vol. AP–44, no. 
 #HANNEL 2ECEIVER #ONSIDERATIONS  -ODERN RADAR SYSTEMS RARELY CON 
 If a radar is to perform surveillance over large areas by ionospheric refraction at all times of day, seasons, and degrees of solar activity, frequency channels distributed over a large part of the HF band are required, although only a single channel may be used at any one time. When the HF band is scanned with a spectrum analyzer at a particular hour, it can be seen that the gross features of occupancy are remark- ably stationary over the days of a season. This is due to broadcast stations, fixed- service point-to-point transmitters, and many other spectrum users having regu- lar schedules. 
 Duru, E. Nielsen, A. Safaeinili, J. 
 ...... 1.8 5 15 40110 ●These numbers arebwed cmanarbitrary, although reavmable, criterion fortrapping, and“Pena simplified model inwhich therefractive index decreases upward through theductatthecomtant rate of8parta in108perfoot. They areintended onlytobeiUustrative. 
 In the special case of the linear FM waveform the same dispersive delay line  that generates the transmitted waveform may be used as the receiver matched filter if the  received waveform is mixed with an LO whose frequency is greater than that of the received  signal. This results in a time inversion (it changes s(t) to s( -t)) by converting an increasing FM  to a decreasing FM, or vice versa.  Dispersive delay lines. 
 A certain amount of attenuation takes place evenwhen radar waves travel through a clear atmosphere. The affect will not benoticeable to the radar observer. The effect of precipitation starts to becomeof practical signiﬁcance at wavelengths shorter than 10cm. 
 BASED RADAR SYSTEM CONFIGURATIONS #OURTESY OF ,OCKHEED -ARTIN #ORPORATION  !.403 
   PP n  /CTOBER    - ) 3KOLNIK  )NTRODUCTION TO 2ADAR 3YSTEMS  .EW 9ORK -C'RAW 
 TRAVELING 
 D. G. Long, M. 
 The only other family of dedicated missions is that in the  Geosat (1985–1989) Exact Repeat Mission (ERM) orbit, the same orbit used by  GFO. This orbit has a period of 17.0505 calendar days (sometimes inappropriately  ch18.indd   37 12/19/07   5:14:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 We deﬁne the slant range error as the ΔR, which can be expressed as: ΔR=Rp0−Rp (15) Equations (6) and (12) indicate that the ΔRis the function of θ. The relationship curve of θand ΔRis shown in Figure 3.S1, S and S 2are marked in the curve. As can be seen from the curve, when the antenna is at point S, the value of slant range error is zero. 
 MATIC RESULT  OF OPTICAL IMAGERY OF THE 7ASHINGTON -ONUMENT WITH THE -ONUMENTS SHADOW POINTED TOWARD THE OBSERVER 7E ASSUME THAT THE SUN IS TO THE SOUTH OF THE -ONUMENT AND THE OBSERVER IS TO THE NORTH 4HE IMAGE SHOWS A SHADOW ON THE NORTH .   39.4(%4)# !0%2452% 2!$!2   £Ç°£ SIDE CAST BY THE SUN 4HE PORTION OF THE -ONUMENT VISIBLE IN THE IMAGE IS THE NORTH  SIDE  ILLUMINATED BY DIFFUSELY SCATTERED SUNLIGHT )N COMPARISON  THE BOTTOM ILLUSTRATION IN &IGURE  SHOWS THE GEOMETRY AND RESULT OF 3!2 IMAGERY  AGAIN WITH THE SHADOW ON THE NORTH SIDE 4HIS TIME THE SHADOW IS CAST BY THE 3!2 ITSELF 4HE PORTION OF THE MONUMENT VISIBLE IN THE IMAGE IS THE  SOUTH SIDE &IGURE  SHOWS THE 3!2 IMAGE )T  DOES NOT LOOK ENTIRELY LIKE AN OPTICAL IMAGE  NOR SHOULD IT !NOTHER DIFFERENCE BETWEEN 3!2 AND OPTICAL IMAGES IS THE PRESENCE OF  SPECKLE  SEE 3ECTION  
 These techniques can result in transistors with bigger  bandgap differences than otherwise possible for the chosen materials. The fabrication  of these transistors employs the use of advanced semiconductor processing such as  Molecular Beam Epitaxy (MBE) or Molecular Organic Chemical Vapor Deposition  ch11.indd   12 12/17/07   2:25:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The dome acts as an RF analog to an optical prisrn  that changes the scan angle of the planar array by a factor K(0). For example, a constant value  of K = 1.5 extends the coverage of a & 60" planar array to +90°. The loss of gain varies in this  case from about 3.8 dB to 5.4 dB over the region of coverage. 
 This arrangement ispreferable toconstant reliance onlocal generation. Aregular maintenance schedule must befollowed, with the emergency engine operated foraminimum ofone hour per week atnoload and a. 584 PRIME POWER SUPPLIES FOR RADAR [SEC. 
 Both rectangular and trian- gular arrays may be simulated, as shown in Fig. 7.20. The impedance measure- ments are made by looking into a waveguide simulator that is terminated with dummy elements. 
 Cheston: Wide Band Phase Shiners, IEEE Trans, vol. AP-15. p. 
 They are relatively small and affordable. On being triggered by a radar  pulse, a SART emits a 12-cycle frequency-swept saw-tooth waveform covering 9.2 to  9.5 GHz. The extension down to 9.2 GHz covers the band used by search aircraft. 
 CAL VALUES OF THE REFLECTION COEFFICIENT ARE NEAR UNITY IE  THE REFLECTED WAVE IS ALMOST AS STRONG AS THE INCIDENCE WAVE  !S THE WIND SPEED INCREASES  THE OCEAN SURFACE GROWS ROUGHER AND THE REFLECTION COEFFICIENT DECREASES &OR A TRANSMITTER NEAR THE SURFACE  THE REFLECTION PROCESS RESULTS IN TWO PATHS TO A RECEIVER WITHIN THE LINE OF SIGHT !S STATED ABOVE  UPON REFLECTION  A PORTION OF THE ENERGY IS PROPAGATED IN THE DIREC 
 During thepast war itwas true, almost without exception, that each new radar system made new demands onthe magnetron and required the development and production ofanew type. This hasnotbeen necessary inthe case ofconventional types oftubes, since the associated circuit elements which arelargely responsible forover-all performance lieexter-. SEC. 
 The preferred magnetron mode of operation is the so-called p mode  that occurs  when the RF field configuration is such that the RF phase alternates 180o (p radians)  between adjacent cavities. The advantage of the p mode is that its frequency can be  more readily separated from the frequencies of the other possible modes. (An N-cavity  magnetron can have N/2 possible modes. 
 operates frorn 406 to 450 MHz witti 1.5 MW peak power, a duty cycle of 0.0039, 47  percerit plate efficiency, arid 13 dB gain. It requires a plate voltage of 17.5 kV, plate current of  183 A. 1.57 V filament voltage and 890 A filament current. 
 Insuch acase, itisonly necessary toestablish anoperating voltage orcurrent.. SEC. 10.4]PEIWORMilNCE CHARTS AND RIEKE DIAGRAMS 339 The performance ofamagnetron interms ofitsoutput parameters, orr-floading, ispresented onaRieke diagram (Fig. 
 BASED PREDICTION OF THE MEDIAN  DENOTED BY THE SMALL CIRCLES   
 PLIES SIMPLER  LIGHTER  AND MORE RELIABLE  ! REDUCTION OF BEAM VOLTAGE IN A CONVENTIONAL  KLYSTRON MEANS AN INCREASE OF THE BEAM CURRENT IN ORDER TO MAINTAIN THE SAME POWER !N INCREASE IN BEAM CURRENT  HOWEVER  RESULTS IN AN INCREASE IN THE CURRENT DENSITY WHERE SPACE CHARGE EFFECTS MAY NOT BE NEGLIGIBLE  AND THE REPULSIVE FORCES THAT OCCUR AMONG THE ELECTRONS ARE INCREASED AND CAN CAUSE THE ELECTRON DENSITY BUNCHES TO LOSE COHERENCE 4HE RESULT IS A DECREASE IN EFFICIENCY (IGHER CURRENT DENSITIES ALSO REQUIRE STRONGER MAGNETS TO KEEP THE ELECTRON BEAM CONFINED  LEADING TO LARGER VOLUME AND WEIGHT 4HUS  SIMPLY LOWERING THE BEAM VOLTAGE AND INCREASING THE CURRENT DENSITY DOES NOT USUALLY PROVIDE A NET ADVANTAGE 4HE LIMITATIONS OF LOWER BEAM VOLTAGE  HOWEVER  CAN BE OVERCOME BY SEPARATING  THE SINGLE ELECTRON BEAM INTO A NUMBER OF SMALLER BEAMS  CALLED  BEAMLETS  SO THAT EACH  OF THE BEAMLETS HAS A LOW ENOUGH CURRENT DENSITY TO AVOID THE UNDESIRABLE REPULSIVE EFFECTS OF A HIGH CURRENT 
 whentheclutterspectrum isrepresented byagaussian function.6Thedifferenc~ between atransversal filterwithoptimal weightsandonewithbinomial weightsforathree­ pulsecanceler (twodelaylines)islessthan2dB.4.5Thedifference isalsosmallforhigher­ ordercancelers. Thustheimprovement obtained withoptimal weightsascompared with binomial weights isrelatively small.Thisappliesoverawiderangeofclutterspectral widths. Similarly. 
 #HANNEL -ONOPULSE  -ONOPULSE RADARS MAY BE DESIGNED WITH FEWER THAN THE  CONVENTIONAL THREE )& CHANNELS 4HIS IS ACCOMPLISHED  FOR EXAMPLE  BY COMBINING THE SUM AND DIFFERENCE SIGNALS IN  TWO )& CHANNELS AND THE  SUM AND TWO DIFFERENCE SIGNAL OUTPUTS  ARE THEN INDIVIDUALLY RETRIEVED AT  THE OUTPUT 4HESE TECHNIQUES  PROVIDE SOME ADVANTAGES  IN !'# OR OTHER PROCESSING TECHNIQUES BUT AT THE COST OF REDUCED 3.2  REDUCED ANGLE DATA RATE  AND POTENTIAL FOR CROSS COUPLING BETWEEN AZIMUTH AND ELEVATION INFORMATION ! TWO 
 J. Rcs. Not. 
 Thus  the mechanical engineer and the skilled machinist and technician are just as important as  the antenna designer in realizing the desired radiation pattern.  Effects of phase shifter quantization.82·115 The discrete value of phase shift that results from  the use of quantized phase shifters introduces an" error" in the desired aperture illumination.  Phase quantization can cause a loss in antenna gain, an increase in the rms sidelobe level, the  generation of spurious sidelobes, and a shift in the pointing of the main beam. 
 These radar design  parameters allow an exceptional sensitivity of –26 dBZ at the Earth surface. CloudSat  orbits in formation with four other satellites as part of the so-called A-train constel - lation of satellites that provide combined radar, lidar, and radiometric measurements  for Earth studies. The CPR on-board CloudSat has 500 m vertical resolution with a  1.4 km footprint and is similar to the NASA Airborne Cloud Radar that has flown for  several years on board the NASA DC-8 aircraft173. 
 STATIONARY HOT CLUTTER CANCELLATION v #HAPTER  IN  !PPLICATIONS OF 3PACE 
 RANGE EFFECT AND THE PLATFORM 
 This can bedone within limits byadding afixed voltage tothe circuit, but over any extended angle itisnecessary tointroduce theshift mechanically byusing adifferential gear orbyrotating the body of thepotentiometer. This requires either that thepotentiometer benear theoperator orthat aremote mechanical control beprovided. Since the second method iscostly, some other data-transmission system isusually chosen inpreference. 
 BASED REMOTE  SENSING RADARS 4HE FOCUS IS ON 4YPE )) 3"2S  AS OUTLINED IN THE PREVIOUS EDITION OF THIS (ANDBOOK  INCLUDING BOTH %ARTH 
 I, GEC (Electronics) Ltd., Memo. SLM 1802, Stanmore, England, July 1967. 109. 
 --  -AJOR ADVANCES IN ANALOG 
 Figure 14.10 shows the relationship between the RCS and the mass of an insect,  with the variation of a water droplet shown for comparison. Table 14.3 lists the  RCS of a man as reported by Schultz et al.16 Other comparisons have been made  for both birds and insects.17FIGURE 14.8  RCS patterns of a trihedral corner reflector. Edge  of aperture = 24 in; l = 1.25 cm. 
 1233.pdf, 2006. 149. T. 
 Acrystal-current jack and decoupling filter areprovided. The first sixtubes are i-famplifiers whose interstage coupling networks are single-tuned circuits arranged intwo stagger-tuned triples. The center frequencies ofthese circuits are, inorder, 30.0, 33.7, 26.7, 33.7, 26.7, and 30.0 Me/see, giving anaverage over-all i-fbandwidth of5.5 Me/see centered at30~1.5Me/see. 
 Radomes are used when it is necessary to protect antennas from  adverse environmental effects. Ideally, a radome should be perfectly transparent to the  RF radiation from (or to) the antenna and yet be able to withstand such environmental  effects as wind, rain, hail, snow, ice, sand, salt spray, lightning, and (in the case of  high-speed airborne applications) thermal, erosion, and other aerodynamic effects. In  practice, these environmental factors determine the mechanical design of the radome,  and the desire for ideal RF transparency must be compromised because mechanical  and electrical requirements are often in conflict. 
 Walker, J. L.: Range Doppler Imaging of Rotating Objects, IEEE Trans., vol. AES-16, pp. 
  TO  
 COMPRESSION SIDELOBES FROM FIXED CLUTTER RETURNS VARY FROM PULSE TO PULSE  THEY DO NOT CANCEL 4HIS COHERENCY ISSUE HAS BEEN FURTHER DISCUSSED BY 4AYLOR  2ULE  0ROVIDE )& ,IMITERS PRIOR TO !$ CONVERTERS -4) RADARS REQUIRE THAT )&  BANDPASS LIMITERS EXIST PRIOR TO AN !$ ANALOGDIGITAL CONVERTER  4HE LIMITER PREVENTS ANY CLUTTER RETURN FROM EXCEEDING THE DYNAMIC RANGE OF THE !$ 4HIS REQUIREMENT EXISTS FOR EITHER QUADRATURE )  1 IN 
 BASED RADAR ALTIMETER %XAMPLES ARE DRAWN FROM THE DESIGN OF 4/0%8   0ULSE 
 § ©¨¶ ¸· 
 For optimizing the  resolution, the shape of the pulse should be optimized.  The ideal result would be:   € =0für t1≠t2 ∫ ;=1für t1=t2 ∫  (5.15)  If the targets are different in size, then one should bear equation (5.14) in mind. The auto - correlation will then become a cross -correlation. 
 Avrin: Satellite-Borne Radar for Global Air Traffic Surveil- lance, IEEEELECTRO '82 Prof. Sess. Rec., Boston, May 25-27, 1982. 
 Path 1 is the shortest, path 4 is the longest and paths 2 and 3 are equal. Thus, there can be three  separate responses from a target, as illustrated in the idealized sketch of Fig. 14.1 1. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.68  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 a function of frequency. 
 These independent beams can be steered in any  direction. DBF at the subarray level can produce a multiple, simultaneous beam clus - ter located within the subarray pattern. DBF at the subarray level uses phase shifters  at the element and an analog subarray beamformer, with a digital receiver located at  the output of each subarray. 
 The maiden voyage for this radar was aboard Challenger (Shuttle) STS-7 on June 22, 1983.15 During the STS-Il flight in February 1984, the Ku-band radar assisted in the checkout of the manned maneuvering unit (MMU) operations. The radar acquired and tracked mission specialist Robert Stewart in the MMU during his 300-ft sojourn into space. The radar measured the radar cross sections (RCS) of the MMU, which varied between 2.5 and 7.5 dBsm with acquisition at a range of 100 ft and track out to the maximum range of 308 ft. 
 $IGITAL #ONVERTER !$4 !UTOMATIC $ETECTION AND 4RACKING !& !MBIGUITY &UNCTION !&3 !UTOMATIC &REQUENCY 3ELECTION !'# !UTOMATIC 'AIN #ONTROL !-& !DAPTIVE -ATCHED &ILTER !0) !PPLICATION 0ROGRAMMING )NTERFACE ! 
 151  13.3.8 ACC Sensor System Specification ........................................................................ 153  13.3.9 MMIC Integration ................................................................................................. 153  13.3.10 Problem Areas ..................................................................................................... 
 STATE TRANSMITTERS )T IS NOT LIKELY THAT MAGNETRONS WILL BE USED IN  HIGH PERFORMANCE RADARS  ESPECIALLY THOSE THAT REQUIRE AVERAGE POWERS MORE THAN ONE  OR TWO KILOWATTS OR WHERE -4) IMPROVEMENT FACTORS HAVE TO BE GREATER THAN  TO  D" &OR EXAMPLE  DURING THE PROCUREMENT OF THE .EXRAD DOPPLER WEATHER RADAR IN THE MID 
 Homing on Aircraft .—During the war, defensive night fighters equipped with radar were developed asareply tonight bombing attacks. The homing problem faced bytheAircraft Interception, .41, radar used forthis purpose ismore difficult than that presented inthe sea-search. SEC. 
 In IF sampling  receivers, the IF filter acts as the anti-aliasing filter and limits the bandwidth of signals  entering the A/D converter. In receivers using baseband conversion, the IF filter sets the  receiver bandwidth. Subsequent video filtering should be of greater bandwidth to prevent  the introduction of I/Q imbalance due to filter differences between I and Q channels. 
 Echoesfrom theforward andrearportions ofthetargetmightbeobscured inthenoise,iftheradarisnot surficiently powerful. High-range-resolution withmonopuhe. Theinclusion ofamonopulse angle-measurement toa high-range-resolution radarwasmentioned brieflyinSec.5.8.Resolution inrangeofthe individual targetscattering-centers permitsananglemeasurement ofthescatterer withoutthe errorsintroduced bytheglintcausedbymultiple scatterers withinthesameresolution cell. 
 In the doppler region where the sjgnal does not fall in clutter, performance is limited only by system noise. The signal-to-noise ratio in the detection filter prior to postdetection integration for a target at range R is given by SNR = (^) (17.19) IPA G7G^X2CT7A174 TR 7 \ (4^kT5BnL I where R0 = range at which S/N = 1 <JT - target radar cross section L = losses applicable to the target The remaining terms are as defined following Eq. (17.2). 
 1971  I 8. Smith. W .. 
  
 The range resolution from Equations (9.1) & (9.3) correspond to the notation and identif iers  from Figure 9.1.  € Δx=cτ cosα⋅1 cosα=cτ 2⋅secα (10.3)  10.2.2  Improvement of the Azimuth Resolution   For the resolution of the azimuth according to Equation (9.2) only the range R and the half - power bandwidth θH are suggested.  Consequently, with the search for possibilities for the  improvement of the resolution orthogonal to the propagation direction, there re main no other  altern atives than the reduction of θH. 
 Eventually, however, therate ofincrease ofplate current falls offand the current tothegrid pulls thelatter downward. Regeneration takes place I+ II Plate1 I 11 II Point z ~ uuuIi II Cathode1 I n n n t.t, Sm;::;:g AMAMAMA Grid when counting down w FIG. 13.19.—The blocking oscillator. 
 The aperture illumination is sensed by a conical scan or monopulse feed and  the antenna is repositioned to maintain the signal-to-noise ratio a maximum.  'I'riangular arrangement of ele~nents.'~~ 154 If the elements of a planar array are arranged in a  pattern of equilateral triangles rather than squares, a savings can be had in the total number of  elements needed. This assumes that the number of elements in an array is determined by the  requirerrient that no spurious beams (grating lobes) appear in the radiation pattern. 
 It has been  suggcstcdJ tliat a practical procedure for estitnatitig tlie required aperture and prf is to size the  arite~ina sucll tliat tlie required swatli and processed doppler bandwidth are within the 6-dB  two-way antenna pattern, arid tlie prf is sucli tliat the unambiguous time-delay and doppler  intervals are within the 16-dB response.  Tliere is another factor wliich reduces the right-hand side of Eqs. (14.10) or (14.1 lh) when  optical processirig or similar processing is used. 
 Rev., vol. 71.  pp. 
 10.18 Loss in signal-to-noise ratio ver- sus doppler shift for linear FM.DOPPLER SHIFT DOPPLER SHIFTSIDELOBE LEVEL (decibels)S/N LOSS (db) . TABLE 10.10 Optimum Stepped-Amplitude Time-Weighting Functions FIG. 10.19 Stepped-amplitude time weighting. 
 LATION IS A BINARY PHASE CODE )N THIS CASE  THE COEFFICIENTS ARE EITHER    OR n  SO THE  ARITHMETIC PERFORMED FOR EACH SAMPLE IS A COMPLEX SUM OR SUBTRACTION INSTEAD OF    A FULL COMPLEX MULTIPLICATION 0ULSE COMPRESSION MAY ALSO BE ACCOMPLISHED BY OPERATING IN THE FREQUENCY DOMAIN   WHERE IT IS REFERRED TO AS  FAST CONVOLUTION )N THIS CASE  THE BASEBAND SAMPLES OF THE  RECEIVE DATA AND THE REFERENCE TRANSMIT WAVEFORM ARE PASSED THROUGH FAST &OURIER TRANSFORMS &&4S   THE DATA &&4 OUTPUTS ARE MULTIPLIED POINT 
 Radar System Engineeri ng Chapter 8 – Pulse Radar  68       DelayDelayDelay DelayDelayDelay DelayDelayDelay DelayDelayDelay 234 5 6 7 8 910111213++++--+-++ SUM 1 Input from receiver Decoded output   Figure 8.24  Barker Decoder for N = 13.   Characteristic of the Barker Code up to N=13 is that all side lobes are ≤ 1, while the main lobe  is equal to N.  Figure 8.25 shows the mathematical process of the circuit in Figure 8.24. 
 The RF echo signal is heterodyned with the stalo signal to produce the IF  sigr~:rl j~rsl ;IS ill !l~c co~ivcr)!io~i;~l srrl~crlictc~~otlyr~c receiver. 7'11~ stnlo, col~o, and the rnixer- in  wliicll tlicy arc co~ilbitlcd plus any low-level aniplificatio~i are called the r~ccc~iuc~r~-c.uc~iti~t~ Iw-  carlsc of tlic dr~al rolc they scrve in both the receiver and the transmitter.  I'lic cliaractcristic feature of collcrc~lt MTI radar is that tile transmitted signal must hc  colicreiit (in pliase) witli the reference signal in the receiver. 
 Note that if the multiple transmitting beams are contiguous and at  the same frequency, the composite transmitted pattern is similar to the pattern from a single  beam encompassing the same angular region.  The receiving beam-forming network may be at IF or RF. Tapped delay lines have been a  310INTRODUCTION TORADAR SYSTEMS Radiating elements I------~t- InputPickuphorns--- Pillbox used as array , feed /- L ~"---~Radiated energy Feed..-IF------ ~L:t=;==':r -Input./ i" I', ( (: I I I \ \ \ (a) (b) Figure8.24Example ofapillboxantenna(shownin(a))usedasafl:cdforanarray(b).(~1i('rRicanJi.1td) (\8.7SIMULTANEOUS MULTIPLE BEAMS FROM ARRAY ANTENNAS "- Oneoftheproperties ofthephasedarrayistheabilitytogenerate multiple independent beam:.. 
 Stem, E., and G. N. Tsandoulas: Ferroscan: Toward Continuous-Aperture Scanning, IEEE Trans. 
 Thisisthedoppler angular frequency UJd. givenby (3.1) (3.2£1)where f~=doppler frequency shiftandl',=relative(orradial)velocityoftargetwithrespect toradar.Thedoppler frequency shiftis .2v,2v,J~Jd=-r =-c~ where/0=lranslllilleo frequency anu('=velocityofpropagation =3x108m/s.Iffdisin hertz.",inknots.andAinmeters, r._1.OJvr d-A(3.2b) Aplotofthisequation isshowninFig.3.1. Therelativevelocity maybewrittent',=Vcos(J,wherevisthetargetspeedand()isthe anglemadebythetargettrajectory andthelinejoiningradarandtarget.When()=O.the doppler frequency ismaximum. 
 The ambiguity function is similar to that provided in the discussion of NLFM,  which is expanded in Figure 8.23 to show in more detail the impact of doppler shift on  the pulse compressed waveform for practical values of doppler shifts.FIGURE   8. 21 cosn on pedestal weighting function (shown for n = 2)k −B/2 B/21 W(f) f FIGURE   8. 22 100-µs PNL pulse autocorrelation function for TB = 100, a = 0.7, and fd = 0 ch08.indd   23 12/20/07   12:50:35 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 ! AIRCRAFT AND CAN BE MECHANICALLY ROTATED  on IN ELEVATION FOR OPERATION LOOKING OUT EITHER SIDE OF  THE AIRCRAFT 4HE SYSTEM OPERATES IN A SYNTHETIC APERTURE RADAR 3!2  MAPPING MODE AS WELL AS IN A THREE 
 DIMENSIONAL MOTION FIELDS IS GENERALLY NOT BETTER THAN &)'52%     2ADAR REFLECTIVITY CONTOURS AND  AIR FLOW VECTORS SUPERPOSED ON PHOTOGRAPH OF A RAP 
 29.  pp 1358 · 1368. September. 
 Tech. J ., vol. 26, pp. 
 This factor Giscalled the “gain” ofthe antenna inthe direction inquestion. Byour definition, thegain ofthehypothetical isotropic radiator is1inevery direction. For any other antenna Gwill begreater than 1insome directions and less than 1inothers. 
 1 Since thevoltage drop across theleakage inductance isapproximately LI.~)the maximum permissible value ofleakage inductance can be estimated byassuming that the current inRLmust reach 90percent of itsfinal value, VO/RL, inatime ofabout to/10. The current which flows must satisfy theequation V,=LZ.$+i. R.. 
 GAIN AUXILIARIES INSTEAD OF ONE   AS SHOWN IN &IGURE   FOR THE 3," BECAUSE THEIR PHASE CENTERS WILL BE DIFFERENT  THE GRATING LOBES AFFECTING THE ADAPTED PATTERNS OF THE  TWO 3," ANTENNAS WILL BE DIFFERENT  TOO 4AKING THE GREATER OF THE TWO ADAPTED 3," SIGNALS  THE GAIN MARGIN BETWEEN THE 3," AND THE MAIN ANTENNA SIDELOBES WILL INCREASE WITH A CONSEQUENT IMPROVEMENT OF THE PERFORMANCE OF THE BLANKING LOGIC&)'52%  ! PROCESSING SCHEME INCORPORATING 3,# AND 3," DEVICES !  !   ! "      #  #       #  #         #  #     
 London, TEE Conference Publication no. 105, pp. 405-408, available from IEEE, New York,  77CHl271-6 AES. 
 They are realized well enough forpractical purposes ifthe following conditions arefulfilled: 1,Nolarge obstacles intervene between antenna and target, along anoptical line ofsight. 18. ~EC. 
 103.Johnson, M.A.:Phased-Array BeamSteering byMultiplex Sampling, Proc.IEEE,vol.56. pp.1801-1811,November, 1968. 104.Radford. 
 SQUARED )N ADDITION  AMPLITUDE FLUCTUATIONS IN THE 2& DRIVE WILL ALSO CAUSE DRIVE 
 POL MODE 0RIMARY INTEREST IN FULLY POLARIMETRIC RADARS DERIVES FROM THE ENRICHED SCATTERING  OBSERVATION POSSIBILITIES REVEALED THROUGH  REPLACEMENT OF THE SCALAR FORM OF REFLECTIV 
 CONVERT THE RADAR SIGNALS FROM THE NANOSECOND TIME FRAME TO A MILLISECOND TIME FRAME THAT IS EASIER TO POST PROCESS (OWEVER  A REAL DISADVANTAGE OF THE SAMPLING RECEIVER IS ITS LIMITED DYNAMIC RANGE DUE TO THE SAMPLING DIODES AND INHERENTLY HIGH NOISE LEVEL DUE TO ITS WIDE BANDWIDTH $ETAILS OF TYPICAL SAMPLING RECEIVERS  WHICH ARE ESSENTIALLY THE SAME AS SAMPLING OSCILLOSCOPES  CAN BE FOUND IN THE LITERATURE  AND ONCE ISSUES OF SAMPLING LINEARITY IN TIME ARE ADDRESSED  THE GENERIC DESIGN HAS FORMED THE BASIS FOR THE MAJORITY OF COMMERCIAL '02 SYSTEMS ! KEY PARAMETER FOR MOST '02 SYSTEMS IS THE MEAN POWER 4HE TIME 
 There is no range gate overlap. The first gate  of the N range gates are blanked for the transmit pulse. As shown in Figure 4.21, this  approximation is only valid for a Pd near 50%. 
 AGILITY RADARS 4RANSPONDER JAMMERS GENER 
 92.BartomD.K.:LowAngleTracking. Microwave J.,vol.19.pp.19-24,December, 1976. 93.Howard. 
 Also, with solid-state components peak power is usually little greater than average power; CW then becomes additionally attractive, particularly if the required average power is within the capability of a single solid-state component. Another very apparent advantage of CW (unmodulated) radar is its ability to handle, without velocity ambiguity, targets at any range and with nearly any con- ceivable velocity. With pulse doppler or moving-target indication (MTI) radar this advantage is bought only with considerable complexity. 
 2012 ,21, 3026–3033. [ CrossRef ][PubMed ] 180. Sensors 2018 ,18, 3750 14. 
 TERERS IN DIFFERENTIAL 3!2 INTERFEROMETRY v  )%%% 4RANS 'EOSCIENCE AND 2EMOTE 3ENSING   VOL    PP n    4 ( $IXON  & !MELUNG  ! &ERRETTI  & .OVALI  & 2OCCA  2 $OKKA  ' 3ELLA  3 
 T       4HE PULSE AMPLITUDE CHANGE MUST BE LESS THAN  $! !        PERCENT     4HE  !$ SAMPLING TIME JITTER MUST BE LESS THAN   *  r r 
 PLER SPECTRA  BOTH OF WHICH ARE OFTEN REQUIRED TO BE  D" OR MORE BELOW THE CARRIER (ARMONICS CAN CREATE INTERFERENCE IN OTHER ELECTRONIC EQUIPMENT 3PURIOUS DOPPLER SPECTRA LEVELS ARE DICTATED BY REQUIREMENTS TO SUPPRESS CLUTTER INTERFERENCE THROUGH DOPPLER FILTERING (ARMONICS ARE GENERATED BY ANY COMPONENT THAT BECOMES NONLINEAR WHEN SUB 
 15. Pugh. S.. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation.  THE PROPAGATION FACTOR, FP, IN THE RADAR EQUATION  26.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 26.8 AREPS RADAR SYSTEM   ASSESSMENT MODEL The main purpose of AREPS is to offer radar operators the ability to visualize their  radar’s detection of threat targets or their own platform’s detection by threat radars  under various natural environmental conditions. 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 24.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 The target angular coordinates—azimuth and elevation ( q, f)—can be estimated by  ML, also in the presence of main-beam and sidelobe jamming, by processing the data  received by a set of low and high gain beams. The set of received radar echoes, V ≡  bS(qT, fT) + d, depends on the angular coordinates of the target, ( qT, fT), the complex  target amplitude b, and white gaussian zero mean noise plus jamming disturbance d. 
 Van Nostrand Company, Inc., Princeton, N.J., 1955, pp. 440-442.  32. 
 DELAY CORRECTION CAN ALSO BE  IMPLEMENTED EFFECTIVELY IN TH E DIGITAL DOMAIN  AND  IF FREQUENCY DEPENDENT PHASE AND AMPLITUDE IMBALANCE CORRECTION IS REQUIRED  THIS IS MOST EASILY AND EFFECTIVELY PERFORMED IN THE DIGITAL DOMAIN USING &)2 FILTERING OF THE ) AND 1 DATA OR BY PERFORMING CORRECTIONS IN THE FREQUENCY DOMAIN DATA  AS PART OF THE  RADAR SIGNAL PROCESSING .ONLINEARITY IN  ) AND 1 #HANNELS #OMPONENT TOLERANCES OFTEN LEAD TO SOME 
 Lockheed Tests Large Space Antenna, Aviat. Week Space TechnoL, vol. 120, p. 
 Inthefirst place liquid water isavery imperfect dielectric atmicrowave frequencies, and absorbs energy from anoscillat- ingelectric field just asany 10SSY dielectric WOuld. .For extremely small drops, such asthose infog orclouds, this isthe only important effect, and inthis limiting case theattenuation atagiven wavelength issimply proportional tothe aggregate liquid water content ofthe atmosphere, 1JH.VanVleck, op.cit.; seealsoVol. 13.. 
 Each module is air-cooled, and the measured efficiency is greater than 25 percent when the module is operating at an 8.2 percent average duty cycle. Module power gain is greater than 16 dB. Figure 5.19 shows a photograph of the 50-lb module and the lineup of power transistors down the center spine of the module. 
 Consider thegeometry ofFig.12.1forpropagation overaplanereflecting surfa~e.There arefourpossible pathsbywhichtheenergytravelstothetargetandback.Theseare: 1.Fromradartotargetandreturnbythesamepath(AB-BA). 2.Fromradartotargetandreturnviareflection fromthesurface(AB-BMA). 3.Fromradartotargetviareflection fromthesurfaceandreturndirectly totheradar (AMB-BA). 
 A. Donelan, “Radar scattering and equilibrium ranges in wind-generated  waves with application to scatterometry,” J. Geophys. 
 ch24.indd   66 12/19/07   6:01:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 444–460, September 1961.  6. “Final report on instrumentation radar AN/FPS-16 (XN-2),” Radio Corporation of America,  unpublished report NTIS 250500, pp. 
 48.Stern.E..andG.N.Tsandoulas: Ferroscan: Toward Continuous-Aperture Scanning, IEEETral/s. vol.AP-23.pp.15-20.January. 1975. 
 3  RADAR BASIC PRINCIPL ES ................................ ................................ ................................ 
 41. M. T. 
 Each of these units is described in more detail below. The key radar parameters for ASV Mk. IIIA are given in table 3.1. 
 In the three-axis arrangement of (h) a  stable base is provided in which a roll axis lies in a fixed position parallel to the fore-and-aft  line of the vehicle. This axis carries the pitch axis that supports the train axis. Pitch and roll  signals from a stable vertical are applied as inputs to the corresponding axes. 
 T    WHERE ! IS THE AMPLITUDE   4 IS THE TRANSMIT PULSEWIDTH   F IS THE CARRIER FREQUENCY   FD   IS THE DOPPLER FREQUENCY   S IS THE SIGNAL TIME DELAY  AND  @ IS THE ,&- SLOPE FOR THE  TRANSMIT WAVEFORM 4HE REFERENCE WAVEFORM APPLIED TO THE ,/ PORT IS   XTT 4FT T22 222 2   COS;     
 . DETECTION PROCESSING A TYPICAL WAVEFORM  MIGHT BE  
 TO 
 The single face phased-array radar is 12.5 m long, mounted on a Heavy Expanded  Mobile Tactical Truck and capable of being transported in a C-130 Hercules aircraft.  The radar is nonrotating and has a 120º field of view. The radar uses its 9.2 m2 full  field-of-view phased array aperture to acquire theater missile threats at a range of up  to 1,000 km. 
 *  Multiplicative noise, a standard specification in synthetic aperture radar, includes unwanted contributions such as  ambiguities and quantization noise that are proportional to the strength of the received signal. ch18.indd   18 12/19/07   5:14:11 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 SYNTHETIC APERTURE RADAR  17 .56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 platform passes by the target, the beam direction moves to keep pointing at the target.  In this way, ∆q  may be made considerably greater than qB, and dcr (spotlight) < dcr  (stripmap). We may wish to make a correction for the variation in received power  (∼1/R4) as the range to the target varies slightly over the synthetic aperture. 
 In addition to causing errors in the  elevation-angle tracking, it is also possible for surface-reflected multipath ·10 introduce errors  in the azimuth-angle tracking; either by" cross-talk" in the radar between the azimuth and  elevation error channels, or by the target-image plane departing from the vertical as when over  sloping land or when the radar is on a rolling and pitching ship.  The surest method for avoiding tracking error due to multipath reflections ,via the surface  of the earth is to use an antenna with such a narrow beamwidth that it doesn't illuminate the  surface. This requires a large antenna and/or a high frequency.44 Although such a solution  eliminates the problem, there may be compelling reasons in some applications that mitigate  against the large antenna needed for a narrow beamwidth or against operation at high  frequency. 
 Thus, they are known as slow-wave tubes . The characteristic  size of the increments of the RF structure of slow-wave tubes is typically a fraction  of a wavelength. They become smaller as the frequency is increased (wavelength is  decreased). 
 56)1 Range-measuring doppler syetem, two transmitted frequencies (Sec. 57)2 c 4frc%fD f,<-:-.Zrn,.. —L--4 +fr F-m range measuring sys- tem (Sec. 
 ALTITUDE TRACKING OVER ROUGH SURFACES )) %XPERIMENTAL AND  MODEL COMPARISONS v IN )%%% %!3#/. 
 1522-1553, 1979. 11. Stimson, G. 
 In this case, the scan frequency will lie, it is hoped, below any doppler of interest, with the result that the conical-scan frequency will appear as small-amplitude sidebands on the doppler frequency when it is recovered in the equipment. In the material that follows, these secondary issues will be largely ignored, and an unmodulated CW transmission plus a receiver that introduces no intentional modulation will be assumed. FIG. 
 21.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 The first and simplest system is stepped frequency continuous wave radar. The second  form is more complex in that each individual frequency is appropriately weighted in  amplitude and phase prior to transmission. Normally, the radar is calibrated both to  establish a reference plane for measurement as well as to reduce the effect of variations  in the frequency characteristics of components and antennas. 
 ch16.indd   19 12/19/07   4:55:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 AP-36, pp. 127–135, 1987.  97. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.736x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 can be found in Figure 20.41, which compares GRWA VE predictions with experimen - tal measurements of the signal strength received at a shore-based HFSWR when the  transmitter was carried by a small boat traveling out to a range of ~110 km.156 To avoid  peripheral issues concerning antennas, the GRWA VE curves have been arbitrarily nor - malized here to align with the measurements at a range of 40 km. It is clear that, with  this normalization, the predictions match reasonably well over the whole range extent,  with small but systematic departures. 
 10. !Oc, on the other hand, has a standard deviation 15  percent greater than optimum, and the estimator based on the maxiff um value has a constant  bias.66 Its relatively good angle-estimating accuracy, good detection performance, along with  the relative simplicity of a feedback integrator makes the two-pole filter a good..Jchoice as an  automatic detector for scanning radars.  10.8 CONSTANT-FALSE-ALARM-RATE (CFAR) RECEIVER  The threshold at the output of a radar receiver, as discussed in Sec. 
 S. J. Anderson, P. 
 R-274, DDC Doc. AD 65881, March 1, 1954. (Reprinted in Reference 6.)  2. 
 ELECTRONIC COUNTER-COUNTERMEASURES  24.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 The first configuration is regular with two elements for each sub-array. The second  configuration is irregular with 2, 1, 4, 2, 1, and 2 elements, respectively. Figure 24.11  shows the SINR at the output of the array versus the jammer DoA. 
 Diode mixers are in each of the  remaining two arms of the magic T. At one of the diodes the sum of the RF and LO signals  appears, and at the other diode the difference of the two is obtained. (In a magic T the LO  would be applied to the H-plane arm, and the RF signal would be applied to the E-plane arm. 
 It is possible to achieve low time-sidelobes with uniform-amplitude transmitted wave­ forms and no theoretical loss in signal-to-noise ratio by means of nonlinear FM, as dis­ cussed later in this section.  Doppler-tolerant waveform. Ir an unknown doppler-frequency shift is experienced when a long  pulse, a noise-modulated pulse, or a pulse train is reflected from a moving target, a receiver  tuned to the transmitted signal will not accept the echo signal if the doppler shift places the  echo frequency outside the band of the receiver matched filter. 
 130.Clarricoates, P.J.B.,andG.T.Poulton: High-Efficiency Microwave Reflector Antennas-A Review, Proc.IEEE,vol.65.pp.1470-1504, October, 1977. 13!.Green,T.J.:TheInfluence ofMastsonShip-Borne RadarPerformance, RADAR-77, Oct.25-28, 1977.London, lEEConference Publication no.lOS,pp.405-408, available fromIEEE,NewYork, 77CI-II27I-6 AES. 132.SecSec.12.10ofref.1. 
 R. Jarrett, “Bandpass signal sampling and coherent detection,” IEEE Trans.  On Aerospace Electronic Systems,  vol. 
 115. R. Kwok and W. 
 S., and D. C. Lorti: Spaceborne Bistatic Radar—An Overview, Proc. 
 R. Neureuther: Radar Cross Section of  a Long Wire, IEEE Trans., vol. AP-17, pp. 
 Still another value that  has been suggested is77 "% j'  Z = 1000r'.6 (13.27)  There does not seem to be any agreed-upon value; the reader can take his pick. In all of the  above, the snowfall rate r at the ground is in millimeters per hour of water measured when the  snow is melted.  A radar is usually less affected by snow and ice than by rain because the factor I K J2 in  Eq. 
 S. D. Berger, “Digital radio frequency memory linear gate stealer spectrum,” IEEE Trans .,   vol. 
 BANDING VS TRANSVERSAL  FILTER CANCELER v .AVAL 2ESEARCH ,ABORATORY  .2, 2EPORT   *ULY     7ASHINGTON  $# 53!   ! &ARINA AND 2 3ANZULLO  h0ERFORMANCE LIMITATIONS IN ADAPTIVE SPATIAL FILTERING v  3IGNAL  0ROCESSING  %LSEVIER  VOL   NO  PP n  /CTOBER   + 'ERLACH  h4HE EFFECTS OF )& BANDPASS MISMATCH ERRORS ON ADAPTIVE CANCELLATION v  )%%% 4RANS   VOL !%3n  NO   PP n  -AY   ! &ARINA  ' 'OLINO  , 4IMMONERI  AND ' 4ONELLI  h$IGITAL EQUALISATION IN ADAPTIVE SPATIAL  FILTERING FOR RADAR SYSTEMS !PPLICATION TO LIVE DATA ACQUIRED WITH A GROUND 
 1475-1484, 1986. 72. Lhermitte, R. 
 (14.35)]. The bistatic radar  signal also _increases as either end of the fence is approached since the echo signal is inversely  proportiorial to DfD; [Eq. (14.36)]. 
 D.If..andR.A.Ferrero: Understanding AIDandD/AConverters, IEEESpect/'!/l1l. vol.9. pp.4756.Septemher. 
 ERS MUST ACCOUNT FOR THIS &)'52%   2EGRESSIONS FOR VERTICAL 
 Cheston, T. C.. and J. 
 [ CrossRef ] 24. Jin, K.; Lai, T.; Wang, Y.; Li, G.; Zhao, Y. Coherent integration for radar high-speed maneuvering target based on frequency-domain second-order phase di ﬀerence. 
 Typically, one  might specify VSWR < 2 at full power over an operating range of 5–30 MHz, say, with  an ability to tolerate higher VSWRs at fractional power outputs. Since the antenna ele - ments will be wideband, harmonic filters may be required. For example, one transmit - ter and harmonic filter combination might have a 5 to 9 MHz passband and a stopband  for 10 MHz and higher frequencies; a second combination might pass up to 17 MHz  and reject 18 MHz and higher, and the design would continue in this manner to the  highest frequency of operation. 
 A  480INTRODUCTION TORADAR SYSTEMS variations received fromclutter.Oneoftheseisthecontaminaled-normal pdfwhichconsists ofthesumoftwogaussian pdfsofdifferent standard deviations anddifferent relative weightings.12ThispdfcanbefittedtothedataofFig.13.5forseastateIbyproper selection oftheparameters. Otherpdf'sthathavebeensuggested forapproximating non­ Rayleigh seaclutterincludetheRicean13[Eq.(2.27)],thechi-square13[Eq.(2.40)],andaclass ofpdf'scalledthe"K-distributions" basedonmodeling theclutterasafinitetwo-dimensional random walk.29TheWeibullpdfhasalsobeenexamined formodeling seaclutter.14.15Itisa two-parameter pdf,likethelognormal, butisintermediate between theRayleigh andthe lognormal. IntheWeibull cluttermodeltheamplitude probability densityfunction ofthe voltagevoutoftheenvelope detector is P(v)=exln2C~r-1 exp[-ln2C~r] (13.12) .} where exisaparameter thatrelatestotheskewness ofthedistribution (sometimes called the Weibullparameter), andVmisthemedianvalueofthedistribution. 
 Some laws of nature have a greater importance here.   Basic Principle of Operation   Radar measurement of range, or distan ce, is made possible because of the properties of radiated  electromagnetic energy:    This energy normally travels through space in a  straight line, at a constant speed,  and  will vary only slightly because of atmospheric and weather conditions.   (The effects a tmosphere and weather have on this energy will be discussed later; however, for this  discussion on determining range, these effects will be temporarily ignored.)    Electromagnetic energy travels through air at approximately the speed of light ,    300,000 kilom eters per second or    186,000 statute miles per second or    162,000 nautical miles per second. 
 It is immediately noted that cloud or fog attenuation is an order of  magnitude greater at 3.2 cm than at 10 cm and that nearly another order of magnitude  increase occurs between 3.2 and 1.25 cm. Range and Velocity Ambiguities.  Weather radars utilize a sequence of pulses  to measure the radar reflectivity and doppler characteristics. 
   %,%#42/.)# #/5.4%2 
 (Thisassumes theabsenceofducting.) Theformula forthedistance alongthelineofsight[Eq.(12.14)]shouldnotbeusedasa measure oftheradarcoverage without somereservation. Figure12.7showsthatatarget locatedatthegeometrical horizon isnotinfreespacebutisdefinitely withinUlediffraction regionofthera~ar.Thefieldstrength foratargetontheradarlineofsightmightvaryfrom10 to30dBbelowthatinfreespace.43Thelossofsignalstrength inthediffraction regioncanbe quitehigh.Atafrequency of500MHz,theone-way propagation lossisroughly 1 dB/miat lowaltitudes.Itcanbeevengreaterathigherfrequencies. Therefore, topenetrate 10miles withinthediffraction region,theradarpowerat500MHzmustbeincreased byatleast20dB overthatrequired forfree-space propagation. 
 It is important to sum the field strengths of the individual contributions, complete with phase relationships, before squaring to obtain the total RCS as given by Eq. (11.1). This is tantamount to forming the coherent sum o- = 12Vv^l2 (11.32) p where ap is the RCS of the pth contributor and $p is its relative phase angle, ac- counting for the two-way propagation of energy from the radar to the scattering feature and back again. 
 70, Apr. 30, 1984. 53. 
 - 4HE CHOICE OF SYSTEM DESIGN IS TO A LARGE EXTENT GOVERNED BY THE TYPE OF TARGET  THE RES 
 A  few decibels improvement in receiver noise-figure can be obtained at a relatively low cost as  compared to the cost and complexity of adding the same few decibels to a high-power  transmitter.  There are, however, limitations to the use of a low-noise front-end in some radar  applications.' As mentioned above, the cost, burnout, and dynamic range of low-noise devices  might not be acceptable in some applications. Even if the low-noise device itself is of large  dynamic range, there can be a reduction of the dynamic range of the receiver as compared to a  receiver with a mixer as its front-end. 
 DEPENDENT FILTER CHARACTERISTIC IS GIVEN BY   \   \ SIN     SIN   &F F 2 C F 42M M M    PP    WHERE FM   MODULATION FREQUENCY (Z   2   RANGE M   C   PROPAGATION VELOCITY   r  MS   4   TIME DELAY   2C S  ! SHORT TIME DELAY CAN TOLERATE MUCH HIGHER DISTURBANCES AT LOW MODULATION FRE 
 SCALE STRUCTURE IN THE HIGH LATITUDE IONOSPHERE v  2ADIO 3CIENCE  VOL   PP n   *ANUARYn&EBRUARY   0 ! "ERNHARDT  ' 'ANGULI  - # +ELLEY  AND 7 % 3WARTZ  h%NHANCED RADAR BACKSCATTER FROM  SPACE SHUTTLE EXHAUST IN THE IONOSPHERE v * 'EOPHYS 2ES  VOL   PP  n     2 - 4HOMAS  0 3 7HITHAM  AND 7 ' %LFORD  h2ESPONSE OF HIGH FREQUENCY RADAR TO METEOR  BACKSCATTER v * !TMOS 4ERR 0HYS   VOL   PP n    ! #AMERON  h4HE *INDALEE OPERATIONAL RADAR NETWORK ITS AR CHITECTURE AND SURVEILLANCE  CAPABILITY v 0ROC )%%% )NT 2ADAR #ONF    PP n  + $AVIES  )ONOSPHERIC 2ADIO  ,ONDON 0 0EREGRINUS    * 4HOMASON  ' 3KAGGS  AND * ,LOYD  h! GLOBAL IONOSPHERIC MODEL v .AVAL 2ES ,AB 2EPT    !UGUST     + (OCKE AND + 3CHLEGEL  h! 2EVIEW OF ATMOSPHERIC GRAVITY WAVES AND TRAVELLING IONOSPHERIC  DISTURBANCES n v !NNALES 'EOPHYSICAE  VOL   PP n    ! "OURDILLON  * $ELLOUE  AND * 0ARENT  h%FFECTS OF GEOMAGNETIC PULSATIONS ON THE DOPPLER SHIFT  OF (& BACKSCATTER RADAR ECHOES v 2ADIO 3CIENCE  VOL   PP n    "' &EJER AND - # +ELLEY  h)ONOSPHERIC IRREGULARITIES v  2EV 'EOPHYS AND 3PACE 0HYS  VOL    PP n    # 
 pp. 100- 105.  IIII'FlN'IRONICAI.I.Y SII'I'RI'D P/IASED ARRAY ANTENNA INRADARJJ9 42,Sakiotis. 
 With a surface-based radar, ducting is limited to low angles of elevation so that the  chief effect is to extend the surface coverage.  Since the angle between the radar beam and the duct direction (as defined by the levels of  constant index of refraction) cannot be greater than about lo if power is to be coupled into an  elevated duct, the radar must usually be at an altitude that permits the required shallow  coupling angles to be achieved. The radar in this case will be more sensitive to targets within  the duct than those outside it. 
 Conf. on Acoustics, Speech, and  Signal Processing 1994, ICASSP’94 , Adelaide (Australia), 1994, pp. 105–107. 
 Pulse Repetition Interval ( PRI):  λ θ 22 01 × × × ×≥ ≥× − + + V U BPRIR R R R a azswath sin()(min p p c)   Pulse Width: Rp ≤ Dutymax × PRI × c Minimum Allowable Ambiguous Range: Rmin ≈ h × csc (e + U1 × Bel /2) Range Swath is Geometry and Instrumentation Dependent: Rswath ≤ h × [csc (e − Bel /2) − csc(e + Bel /2)] and Rswath ≤ Rmaxswath             (5.4) where: l is transmitted wavelength, h is the aircraft altitude, Baz & Bel are the azimuth & elevation half power beamwidths, q & e are the angles between the velocity vector and antenna beam center , R1 is the distance to the first range bin, Va is the aircraft velocity, Rswath is the range swath length, Rmaxswath  is maximum instrumented range swath, Rmin is the range to the closest allowable ambiguity, Dutymax is allowable duty ratio, Rp is the transmitted pulse length in distance units, c is the velocity of light, U0, U1 are beamwidth multipliers at predefined power rolloff.FIGURE 5.35  SAR Multirate Filtering ( adapted8; courtesy SciTech Publishing ) ch05.indd   37 12/17/07   1:27:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 
 Hill, R. T.: Phased Array Feed Systems, A Survey, .. Phased Array Antennas, Proceedings of the 1970  Phased Array Antenna Symposium," A. 
 ALTITUDE AIR TARGETS IS REQUIRED %QS n  )F THIS DIRECT PATH SIGNAL IS NOT ATTENUATED  THE RECEIVED SIGNAL BECOMES MASKED IN RANGE AND OFTEN MASKED IN DOPPLER BY SIDELOBES OF THE CORRELATED DIRECT PATH SIGNAL $IRECT 
 The difference is about two  minutes, as an expert Loran operator can seldom get a  full fix in under three minutes, compared with the sixty  seconds or less for Gee.  Within a year after the War American radar experts  had seen much success in the installation of a Loran  chain. Loran coverage stretches west across the Atlantic,  North America, and the broad reaches of the Pacific. 
 4. 17. Finn, H. 
 TION TECHNIQUES HAVE TO BE ABLE TO ACCOUNT FOR THE DOPPLER INDUCED BY RELATIVE MOTION BETWEEN AIRBORNE RADAR AND JAMMER PLATFORMS AND THE JAMMER SIGNAL NONSTATIONARITY THAT IS PRODUCED FROM SUCH A BISTATIC GEOMETRY 43) MITIGATION FOR OVER 
 60 50 (J) 'U I .... 040ti 0 CIL=0dB -CCIL=10dB 41E 4130>0nE 20CIL=20dB na=100 na=50 na=20 na=10 na=5 0010L-_-I-__ ---l..__L-.J'--_..l..-_'----'-----L..L-----l---'---'-_----''-- __..l..-_--'---'---_----' 0·001 (a). Figure 4.32 Effect of limit level on the improvement factor for (a) two-pulse delay-line canceler and  (b) three-pulse delay-line canceler. 
 LOWING SECTIONS -ORE DETAILED DISCUSSION OF 3!2 IMAGERY IS GIVEN BY (ENDERSON AND ,EWIS  AND /LIVER AND 1UEGAN 0OINT 
 “Maritime navigation and radiocommunication equipment and systems—Class B ship - borne equipment of the automatic identification system (AIS),” IEC 62287-1, International  Electrotechnical Commission, Geneva, 2006. 29. “Recommendation A-126 on the use of the automatic identification System (AIS) in marine  aids to navigation,” Edition 1, International Association of Lighthouse Authorities (IALA),  Paris, 2003. 
 347-349, May, 1960.  27. Sandler, S. 
 GROUND NOISE DATA AND THE RATIO TAKEN TO YIELD A POPULATION OF ESTIMATES OF TRUE SUB 
 SION OF THE CODE  TO A STRONG TARGET &URTHERMORE  IT CANNOT BE USED IN CONJUNCTION WITH DOPPLER PROCESSING #&!2 #&!2 IS A TECHNIQUE MADE NECESSARY TO PREVENT THE COMPUTER FROM  BEING OVERLOADED BY FALSE ALARMS  WHICH REDUCE THE CAPABILITY OF THE RADAR TO DETECT DESIRED TARGETS  4HIS PROCESSING ALSO PLAYS A ROLE AS %##- THERE ARE THREE MOTIVA 
 We will see that for bandpass signals a sampling  rate higher than Nyquist may be required to avoid aliasing in some situations. The Nyquist rate is often said to be twice the signal bandwidth, but that refers to a  one-sided bandwidth, positive frequencies only, of a real signal. Our definition refers  to the two-sided bandwidth, both positive and negative frequencies, of a signal that, in  general, is complex with a real signal as a special case. 
  RADAR h4HE  RADAR PROVIDES A UNIQUE SIMULTANEOUS 3!2'-4) ;'ROUND -OVING 4ARGET  )NDICATIONSCANNING REAL APERTURE RADAR= MODE IN WHICH DETECTED  TARGETS ARE DIS 
 JPTXT  D8DF &REQUENCY DOMAIN DIFFERENTIATION   XT  
 Methods of generating and process - ing pulse compression waveforms are discussed in the section on pulse compression  implementation in this chapter. Discussions here will concentrate on the waveform  itself. The primary factors influencing the selection of a particular waveform are usu - ally the radar requirements of doppler tolerance and time sidelobe levels. 
 TATIVE 42 MODULE FUNCTIONS ARE SHOWN IN &IGURE  &UNCTIONALLY  THESE ARE ALL EQUIVALENT  BUT THE PARTITIONING OF CIRCUIT FUNCTIONS IS DEPENDENT ON THE CAPABILITY OF THE --)#S USED  AND DIFFERENT IMPLEMENTATIONS MAY BE REQUIRED TO ADDRESS A KEY RELIABILITY REQUIREMENT OR A KEY PERFORMANCE PARAMETER &OR  EXAMPLE  THE USE  OF A SINGLE HIGH PERFORMANCE POWER AMPLIFIER MAY OBVIATE THE NEED FOR COMBIN 
 In many cases, however, interpolation errors arelarger than canbetolerated; thefixed markers arethen supplemented byamanually controlled, con- tinuously movable, calibrated index. This index has the advantage of extremely high precision, especially onanexpanded sweep, but itrequires appreciable time initsuse. Mechanical indices which move infront ofthe CRT face areseldom used inmeasuring range. 
 DIMENSIONAL RANDOMLY ROUGH SURFACES v  )%%% 4RANS ON 'EOSC AND 2EMOTE 3ENSING   VOL    PP n    3 / 2ICE  h-ATHEMATICAL ANALYSIS OF RANDOM NOISE v PT    "ELL 3YST 4ECH *  VOL   PP n    PT ))  VOL   PP n    ' ! 3HMIDMAN  h'ENERALIZED RADAR CLUTTER MODEL v  )%%% 4RANS ON !EROSP %LEC 3YS   VOL    PP n    2 $ $E2OO ET AL  h--7 SCATTERING CHARACTERISTICS OF TERRAIN AT NEAR 
 Receivers typically provide controlled  limiting (Section 6.8) to prevent the signal level from exceeding the full scale level  of the A/D converter. Practical considerations mean that the hard limit level is typi - cally set 1 dB below full scale to prevent overload as a result of component tolerance  variations. Types of Signals. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.54  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 FIGURE   16. 
 SHAPED ARRAY OF  r    M BICONICAL ELEMENTS GROUPED AS  r  SUBARRAYS WITH RANDOM DISTRIBUTION r VERTICAL CURTAIN ARRAYS OF  MASTS r  VERTICALLY STACKED HORIZONTAL CAGE DIPOLES 2X APERTURE M         ARMS r    LONG  r   WIDE    LONG  r  HIGH  .O OF RECEIVE CHANNELS     2X AZIMUTH BEAM STEERo no  no no  nn 7AVEFORM TYPE ,INEAR &-#7,INEAR &-#7 ,INEAR &-#7 ,INEAR &- #7 ,INEAR &-#7#ODED PULSE "INARY PHASE  CODED PULSE 7AVEFORM REPETITION FREQUENCY (Z ^ n  ^ n n  n      7AVEFORM BANDWIDTHK(Z n TYPICAL n TYPICAL n n  #OHERENT INTEGRATION  TIME S n  !IR MODEn 3HIP MODEn !IR MODEn 3HIP MODEn n 0RIMARY MISSION !IRCRAFT  DETECTION!IRCRAFT DETECTION!IRCRAFT DETECTION!IRCRAFT DETECTION!IRCRAFT DETECTION"ALLISTIC MISSILE DETECTION 3ECONDARY MISSIONS3HIP DETECTION2EMOTE SENSING3HIP DETECTION2EMOTE SENSING#RUISE MISSILE DETECTION3HIP DETECTION3HIP DETECTION2EMOTE SENSING!IRCRAFT DETECTION#RUISE MISSILE DETECTION4!",%  0RINCIPAL $ESIGN 0ARAMETERS FOR 3OME -AJOR (& 3KYWAVE 2ADAR 3YSTEMS    0AST AND 0RESENT   4HIS INFORMATION HAS BEEN COMPILED FROM SOURCES THAT  IN SOME CASES  ARE INCOMPLETE 7HERE ONLY PARTIAL INFORMATION IS PROVIDED  IT MAY STILL BE USEFUL FOR COMPARISON PURPOSES .OTES I  6,0! DENOTES VERTICAL LOG 
 DELAY  NETWORKS AT EACH SUBARRAY LEVEL  THE BANDWIDTH IS INCREASED BY A FACTOR OF  . 4HIS SAME  BANDWIDTH CRITERION LEADS TO A REDUCTION IN GAIN OF ABOUT  D" AND A GRATING LOBE OF ABOUT  
 J. Sachs and P. Peyerl, “Chip integrated UWB radar electronics,” presented at Third DTIF  Workshop, Ground Penetrating Radar in Support of Humanitarian Demining , JRC, Ispra, Italy,  September 2002. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.52  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 The actual numbers for the copolarized response for this case are c = 0° (VV) and  y  = 20°.32 The reference presents similar plots showing separately the polarized and  unpolarized responses. 
 Using these parameters, the theoretical number of samples of the transmitted chirp can be computed as the product of the ERS sampling frequency and the chirp duration, with a close adherence with our 97. Sensors 2019 ,19, 1649 estimate of 704 samples of the proposed technique. Also, the theoretical relative bandwidth of the chirp can be obtained as the ratio between the chirp bandwidth and the sampling frequency. 
 The spectral width of the (sin U)/U envelope  is determined by the transmitted pulse width, the first nulls occurring at a frequency of   f0 ± 1/t. The individual spectral lines are separated by a frequency equal to the PRF.  These spectral lines fall at precisely the same frequencies as the nulls of the MTI filter  response shown in Figure 2.10. 
 TERM BASIS WITH A SUPERIMPOSED RANDOM COMPONENT AND  OCCASIONAL MAJOR STORMS AND OTHER DISTURBANCES &URTHER  THE %A RTHS LOWER ATMOSPHERE  IS COUPLED TO THE IONOSPHERE BY A VARIETY OF UPWARD 
 A., J. J. Kappl, and N. 
 R.: Theory and Design of a Class of Luneburg Lenses, IRE WESCON Co,w. Record,  vol. 2, pt. 
 &ACTOR    THE 4ERRAIN )NTEGRATED 2OUGH %ARTH -ODEL 4)2%-    THE )RREGULAR 4ERRAIN -ODEL )4-  ALSO KNOWN AS ,ONGLEY 
 Tliis has been approximated in some precision tracking radars by a five-horn feed  consisting of one horn generating the sum pattern surrounded by four horns generating the  difference patterns.' Other approximations to the ideal designs include a twelve-horn feedz4  atid a feed consisting of four stacked horns in one plane with each horn generating three  waveguide modes in the other plane.z5 Higher-order waveguide modes are used to obtain the  desired sur~i arid differetice patterns from a sitigle horn without the necessity of complex  TRACKING RADAR163 controltakeplaceinthesingleIFamplifier. Anyvariations affectallthreesignalssimulta­ neously. Afteramplification, compensating delaysareintroduced tounscramble thetimese­ quenceandbringthesumsignalandthetwodifference signalsintimecoincidence. 
 ATIONAL AND TECHNICAL REQUIREMENTS FOR 643 RADARS 4HIS CHAPTER EXPLAINS THE SPECIAL REQUIREMENTS OF #-2  BOTH FROM A PRACTICAL AND  A REGULATORY POINT OF VIEW  AND LOOKS AT THE TECHNOLOGY AND SYSTEM CONCEPTS THAT ARE BEING USED TO MEET THESE REQUIREMENTS 5NTIL THE FIRST DECADE OF THE PRESENT CENTURY  #-2 SHIPBORNE TECHNOLOGY HAD BEEN SOLELY BASED ON MAGNETRONS AS THE BASIC SOURCE OF TRANSMITTED POWER 3INCE   )-/ HAS ENCOURAGED THE USE OF COHERENT RADAR SOLU 
 Guyon, and J. Riom, “Nadir looking airborne radar  and possible applications to forestry,” Remote Sensing Environ. , vol. 
 The filtered  signal adaptively adjusts the aperture illumination to minimize the sidelobes in those direc­ tions from which clutter appears.  The co'1ere11t sidelobe canceler (Sec. 14.5) is a form of adaptive antenna that uses a small  number of auxiliary elements to adaptively place nulls in the direction of external noise  sources. 
 I-. A,: Effects of Raridoni Errors on the Performance of Antenna Arrays of Many Ele-  rlients. IRE Ntrrl. 
 If the change in target coordinates from scan to scan is not  (()O large, it is possible to reconstruct the track of the target from the sampled data. This may  be accomplished by providing the PPI-scope operator with a grease pencil to mark the target  pips on the face of the scope. A line joining those pips that correspond to the same target  provides the target track. 
 22, pp. 758–765, 1983. 63. 
 The two words sole arid c-atl~ode are sometimes ilsed  intercllangeably. Tlie slow-wave structure is designed,so that an RF signal propagates at a  vclocity near tl1at of tlle electron bealn. Tliis permits an exchange of energy frorn the electrori  I~L~~IIII IO ~IIC Ii 1' Iicld to ~>I.OCIIICC i~r~i~~Iific;~tio~t. 
 Purduski114 © IEEE 1980 ) ch16.indd   30 12/19/07   4:55:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 ( 14.12)  When a synthetic-aperture radar images the ground from an elevated platform, the unam­ biguous range can correspond to the distance between the forward edge and the far edge of the  region to be mapped. This requires that the elevation beamwidth be tailored to illuminate only  the swath S,.. that is to be imaged by t_he radar. 
 !  IS SHOWN IN &IGURE  4HE MISSION PROFILE .   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°£Î BEGINS WITH AN AIRFIELD OR CARRIER TAKEOFF  CONTINUES THROUGH FLIGHT PENETRATING INTO  AN ENEMY BATTLE 
 HUMPED IN 
 Power amplifiers for transmitting at the  element level would typically have a gain of  30 dB or more to compensate for the loss of  power dividing in the beamformer. Transistors  are capable of generating high average power  but only relatively low peak power. High  duty-cycle waveforms (10 to 20%) are there - fore required to transmit enough energy effi - ciently. 
 FIELD %Q   AND DOUBLES THE ELECTRIC CUR 
 21, pp. 297–310, 1987. 51. 
 Neither is desirable except in special cases (as in  pulse-<ioppler radar or CW radar). Long pulses result in a long minimum radar-range since  the receiver cannot be turned on until the transmitted pulse is turned oil To see targets al  ranges closer than that determined by the long pulse, a short pulse of lower energy and at a  different frequency can be used in addition to the long pulse. This adds to the syst,em complex­ ity, however. 
 ARRAY RADAR v  0ROC OF THE TH %UROPEAN -ICROWAVE #ONF    "OLOGNA )TALY   3EPTEMBER n    PP n  7 $ 7IRTH   2ADAR 4ECHNIQUES  5SING !RRAY !NTENNAS   ,ONDON  5+ )%% 2ADAR  3ONAR   .AVIGATION AND !VIONICS  3ERIES      * " (OFFMAN AND " , 'ABELACH  h&OUR 
 The primary visualization is a height  versus range display of radar probability of detection, where the radar probability of  detection expressed in percent corresponds to certain energy levels in height and range  from the radar. APM computes propagation loss in dB. To make a determination of  radar performance, AREPS needs to make a comparison of free-space propagation  loss and propagation loss within the Earth’s environment as computed by APM. 
 and the position of the segment indicates the reciprocal or the pointing  direction of the antenna.  )-scope. A modified A-scope in which the time base is a circle and targets appear as radial deflections from  the time base. 
 Thus, similar magnetrons at3000, 10,000, and 30,000 Me/see would have pulling figures of,say, 5,16,and 50Me/see. Since receiver bandwidth isnot changed substantially as the radar frequency increases, frequency stability becomes amore important consideration atshorter wavelengths. The effect ofloading onfrequency stability and methods ofobtaining various loadings have been considered inSec. 
 70. ap Rhys. T. 
 Ó{°ÓÈ  2!$!2 (!.$"//+  )T IS HIGHLY DESIRABLE IN 0!2 TO HAVE LOW SIDELOBES THIS IS OBTAINED BY I  FIXED WEIGHT 
 SELECTIVE DISPERSIVE  OUTPUT TRANSDUCER ARE USED IN &IGURE  A 7HEN AN  IMPULSE IS APPLIED TO THE INPUT  THE OUTPUT SIGNAL IS INITIALLY A LOW FREQUENCY THAT INCREASES BASED ON THE OUTPUT TRANSDUCER FINGER SPACINGS  AT LATER PORTIONS OF THE PULSE 4HIS RESULTS  &)'52%    3!7 TRANSDUCER TYPES A  DISPERSIVE OUTPUT  B  BOTH INPUT AND OUTPUT DISPERSIVE  AND   C  DISPERSIVE REFLECTIONS . 
 °Ó{  2!$!2 (!.$"//+  ERROR 
 The first function of the range tracker is acquisition of a desired  target. Although this is not a tracking operation, it is a necessary first step before range  tracking or angle tracking may take place in a typical radar. Some knowledge of target  angular location is necessary for pencil-beam tracking radars to point their typically  narrow antenna beams in the direction of the target. 
 The line of ﬂight marker painted a radial line on the PPI, triggered at the point when the antenna scanner was aligned with the aircraft forward axis. This could beAirborne Maritime Surveillance Radar, Volume 1 3-12. selected ON or OFF. 
 Note that for sfT ≈ 1 the average SCR  improvement is due only to the coherent integration of all the pulses in the CPI. An MTI filter can also be designed based on the criterion of maximizing the signal- to-clutter improvement at a specific target doppler. However, such a design will usually  provide suboptimum performance at all other target dopplers. 
 TRAVEL BY BEACON  The transponder action of radar beacons—  Essentials of the Babs and SCS-51 systems  —How radar beacons have been developed  from IFF—Scope for radar beaconry—Land-  ing by a ean peal? ees beacon  system—Types 0 display given by beacons — Difference between U.S. and British beacon systems—Height-finding by radat—The AYD and AYF systems.  CONCLUSION  Radar compared with supersonic and pulsed- light techniques—A direct but not inevitable fruit of pure research—How Britain’s re- search into fundamental problems of long- distance commumication gave us the boon of tadar—The necessity for maintaining radar as a civilian function. 
 VI and VIA were undertaken in July 1945 and reported in TRE Report T1894 [ 16]. These measurements were intended to determine the performance stability of ASV Mk. VI and VIA on an operational squadron. 
 This noise is one of the fundamental limitations on the radar range, and for this reason the subject has been treated in Sec. 2.5. The anal- ysis of radar sensitivity is facilitated if the noise contribution of each element of . 
 TIONS AND HAZARDS  NAVIGATION OBJECTS AND SHORELINESv  4HE )NTERNATIONAL !SSOCIATION  OF -ARINE !IDS TO .AVIGATION AND ,IGHTHOUSE !UTHORITIES )!,!  RECOMMENDS OPER 
 TRACK RESOLUTION   RY IS THE GROUND 
 FLOATING POINT MEANS  TO FEWER BITS  TO    AT THE USERS OPTION WITHIN MODE 
 LUTION IN THE SLIP 
 550–564, 1965. 50. R. 
 A. L. C.: Tracking and Associated Problems. 
 The key element in any space-based SAR design is the antenna. It  determines range swath coverage and required minimum transmitter power, and has a  major influence on resolution and data rate. The Magellan antenna, a 3.7-m diameter  dish, was a significant departure from the conventional highly asymmetric rectangular  antennas that were then in favor for SARs. 
 The ISR data was still obtained from Poker Flat ISR station, the ionosonde data was from EIELSON station (ID: EI764), and the PolSAR data was from PALSAR-2 on board Advanced Land Observing Satellite-2 (ALOS-2). Their geographic relationship is shown in Figure 2where the PolSAR scene fully covers the Poker ISR station and EIELSON station is adjacent to the right bottom of the scene. From the “Piercing Lat.” and “Piercing Lon.” in Table 2, we could know that both ISR and ionosonde observe the ionosphere vertically. 
 TO 
 Model response to surface roughness variations and the radar imaging of underwater bottom topography. J. Geophys. 
 Echosignalsreceived afteranintervalexceeding the pulse-repctition pcriodarecalledl/I/11til'le-time-arormd echoes.Theycanresultin erroneous or confusing rangcmcasurcmcnts. Consider thethreetargetslabeledA.B,andCinFig.2.26a. TargetAi~locatedwithinthemaximum unambiguous rangeRunamb[Eq.(1.2)]oftheradar, targctBisatadistance greaterthanRunambbutlessthan2Runamb' whiletargetCisgreater than2Runarnh butlessthan3Runamh. 
 Besides, the imaging conditions of actual SAR images is usually unknown and hard to control, which makes it quite difﬁcult to conclude feature patterns of eddies directly from SAR images. Thus, this paper proposes a simulation method whose results may provide guidance for interpreting the features of the shear-wave-generated eddies in SAR images and facilitate detection and visualization of shear-wave-generated eddies in future works. Shear-wave-generated eddies in SAR images will present brightness variations which correspond to the smoothed and rough region [ 16]. 
  
  
 5Electromagnetic Spectrum Wavelength ( λ, in a vacuum and approximately in air) 10-3 10-210-1 11 0-510-410-3 10-210-1 11 01102 103104 105 109108107106105 104103 102 10 1 100 10 1 100 10 1 Frequency (f, cps, Hz)RadioMicrons Meters Giga Mega KiloMicrowave Millimeter Infrared Ultraviolet Visible Optical 300 MHz 300 GHzEHF SHF UHF VHF HF MF LF Typical radar  frequencies. 6Radar Bands and Usage 8 (Similar to Table 1.1 and Section 1.5 in Skolnik). 7Time Delay Ranging • Target range is the fundamental qu antity measured by most radars. 
 Another method for utilizing the frequency  domain to scan an angular region is to radiate a single frequency-modulated pulse with a  modulation-band wide enough to scan the beam over the entire angular region. Thus, over the  duration of a single pulse, the antenna beam scans all angles. This is sometimes cal.led witlri11- p11lse frequency scanning. 
 6.12 This simple relation permits height tobefound ifthe target range and thedifference angle can bedetermined. There isadanger that at / RadarAD FIG.6.26.—Schematic view ofV-beam principle. Forclarity, vertical andslant beams are shown without the10°separation inazimuth which isused inpractice. 
 60. B. L. 
 Oneofthelimitations ofthesolidhomogeneous dielectric lensisitsthicksizeandlarge weight.Boththethickness andtheweightmaybereducedconsiderably bystepping orzoning thclcns(Fig.7.1HI,).Zoningisbasedonthefactthata360°changeofphaseattheaperture has noeffectontheaperture phasedistribution. Starting withzerothickness attheedgeofthelens, thethickness ofthedielectric isprogressively increased towardthelensaxisasinthedesignof anormal lens.However, whenthepathlengthintroduced bythedielectric isequaltoa wavelength. thepathinthedielectric canbereduced tozerowithout alteringthephaseacross theaperture. 
 Ithasseenwideapplication inradarbecause('fitssimplicity, compact size,andits abilitytotolerateabnormal loadconditions suchascausedbymagnetron sparking. U4.25A diagram ofaline-type pulsemodulator isshowninFig.6.14.Thecharging impedance is shownasaninductance. Thepulse-forming network isusuallyalumped-constant delayline.It mightconsistofanair-core inductance withtapsalongitslengthtowhichareattached capacitance toground.Atransformer isusedtomatchtheimpedance ofthedelaylinetothat oftheload.Aperfectmatchisnotalwayspossible because ofthenonlinear impedance characteristic ofmicrowave tubes. 
 DUTY CYCLE WAVEFORMS  A BISTATIC RECEIVER MAY NEED TO AUGMENT ITS SPA 
 -  !LL COUNTRIES REQUIRE THAT '02 SYSTEMS ARE PROPERLY REGULATED AND OPERATED IN ACCOR 
 1-10, January, 1968, PB  177017.  46. Copeland, J. 
 552INTRODUCTION TORADAR SYSTEMS rangeservolimitsintheradarreceiver areexceeded, orelsetherepeater canbeturnedoff, leavingthetrackerwithout atargetandforcingittoreverttothesearchmode. CWradarssometimes employ atunable filtercalledavelocity gatetotrackthedoppler frequency shift.Avelocity=gate stealertransmits asignalwhichfalsifiesthetarget'sspeedor pretends thatitisstationary. Repeater jammers mayalsobedesigned tobreakconical-scan angletrackbytransmitting asignalattheconical-scan frequency. 
 The basic steps of the algorithm are given in Algorithm 1: Algorithm 1 k-means clustering algorithm 1. Initialize the centroids: Assign kpoints as the initial group centroids. 2. 
 BAND RADAR OPERATING AT A  GRAZING ANGLE OF  AND A RESOLUTION CELL SIZE OF ABOUT  M 4HE ZERO 
 If only that portion of  the aperture distribution which extends over the finite-aperture dimension d were used. the  resulting antenna pattern would be  Ea(¢)= ( A(z)exp j2rr,sin¢ dz • d,' 2 ( z )  · -d/2 11. (7.23)  Substituting Eq. 
 Space-based synthetic aperture radar (SAR) systems capable of 1-m  resolution have become the norm, with systems under development or already launched  by at least seven countries. As expanded in the appropriate sections of this chapter,  the (range) measurement precision of surface height change is now on the order of  1 millimeter per year, as established by two different classes of Earth-observing SBRs  (SARs and radar altimeters). Several nations are sponsoring radars for exploration at  the Moon and beyond. 
 For the data collected from a little subaperture, 28. Sensors 2019 ,19, 490 its scattering can be regarded as constant. Then, the phase history of the i-th ( i=1, 2··· I) subaperture is formulated as ri(fp,θq)=M ∑ m=1N ∑ n=1si(xm,yn)·exp{− j4πfp c·(xmcos(θq)+ ynsin(θq))}+zi, (1) where riis the phase history data of the i-th subaperture, and mand nare the pixel indexes along xand y.Mand Nare the pixel numbers along xand y,sis the scattering reﬂectivity of the i-th subaperture which is located at (xm,yn),fp(p=1, 2··· P)is the frequency, cis the light velocity, θq(q=1, 2··· Q) is the aspect angle, and ziis additive noise. 
 The ability of an operator to extract information efficiently from a CRT display will  depend on such factors as the brightness of the display, density and character of the back-  ground noise, pulse repetition rate, scan rate of the antenna beam, signal clipping, decay time  of the phosphor, length of time of blip exposure, blip size, viewing distance, ambient illumina-  tion, dark adaptation, display size, and operator fatigue. Empirical data derived from exper-  imental testing of many of these factors are a~ailable.~'*~~  There has been much interest in applying solid-state technology as a radar display to  replace the vacuum-tube CRT. Although the light-emitting diode has been too costly and ,  complex to be a general replacement for the CRT, it might be applied when required to display  limited information without the display occupying excessive space, such as in the Distance  from Touchdown Indicator (DFTI) used in aircraft control towers to monitor landing  aircraft.?' Liquid crystal displays which can operate in high ambient lighting conditions have  also been of interest for some special radar requirements, but they also are limited compared  to the capability of a CRT. 
 It predates the  widespread use of the term probability of detection and came about by the manner in which  tile performance of ground-based search-radars was checked. An aircraft would be flown on a  radial course and on each scan of the antenna it would be recorded whether or not a target blip  had been detected on the radar display. This was repeated many times until sufficient data was  ohtai~icd to corni,ute, as a futictior) - - ofrange, -- the ratio of the average number ofscans the target  was seen at a particular range (blips) to the total number of times it could have been seen  (scans). 
 R. Corliss: Worldwide Radio Noise Levek  Expected in the, Frequency Band 10 Kilocycles to 100 Megacycles, Natl. Blcr. 
 The entropies and IC values change are illustrated in Figure 18. The entropy and IC value of the proposed method results have some changes with iteration. This means the image quality shows some improvement. 
 The recovery time of the multipactor  is extremely fast. It has low spike-leakage, and can handle high peak and average powers. The  flat-leakage power passed by the multipactor is high enough to require a passive diode limiter  following the multipactor. 
 RESPONSE  CURVE IS SHOWN IN &IGURE  FOR A SINGLE POINT CLUTTER SOURCE  D" ABOVE THERMAL NOISE THAT FLUCTUATES FROM SCAN 
 14.2 onwave shape. )The majority ofexisting airborne radar sets aredesigned for400-cps minimum supply frequency, and itappears that this will continue tobethe nominal standard. Variable-frequency alternators are also used; they commonly give a2to1ratio between minimum and maximum frequencies, depending onthe speed ofthe aircraft engine. 
 74 HOW RADAR WORKS  condenser voltage begins to approach the supply  voltage. Theoretically, of course, the condenser never  does attain the full voltage of the supply, but, apart  from this hairsplitting point, the essential is that the  current drops to zero at full charge, so that the graph  of voltage against time is of the form yo. , and the  graph of current against time is the converse,  We could attempt to straighten up the voltage-time  curve if, instead of linking the condenser to a constant-  voltage source, we made arrangements to maintain a  constant rate of flow of current into the condenser. 
  RADAR TRANSMITTER v  -ICROWAVE  *OURNAL  VOL   PP n  *ULY   * $YCK AND ( 7ARD  h2!-0S NEW PRIMARY SURVEILLANCE RADAR v  -ICROWAVE *OURNAL  P    $ECEMBER   ( 7ARD  h4HE 2!-0 032  A SOLID 
 Altimeters have been used on many satellites. The technology of SBR subsystems has been developed in the areas of antennas, transmitters, receivers, solid-state transmit-receive (T/R) modules, signal proces- sors, and prime power. This chapter will review SBR systems and technology with the intent to provide a description that is not too sketchy to be substantive. 
 The intersections ofthe horizontal lines with the sawtooth curves give thetimes atwhich replies arereceived byaradar tuned tothe frequency corresponding tothe horizontal line. Incase aallinterroga- tors atdifferent frequency getregularly spaced pulses, incase bthey come inpairs, thegrouping depending onthefrequency. This useofasingle tube forreceiver and transmitter isconvenient especially because ittends tomitigate theeffects ofantenna mismatch often encountered ininstalla- tions inthe field. 
 (G.,)max =maximum value ofthe gain ofthe transmitting antmna oftheinterrogator. (Gs,)max =maximum value ofthegain ofthereceiving antenna ofthe beacon. xi=transmitted wavelength. 
 ALARM RATE4!",%  0ULSE 
 This clutter is generally much  smaller than the main-beam clutter but covers much more of the frequency domain. The  sidelobe clutter from the ground directly below the radar, the altitude-line, is frequently  large owing to a high reflection coefficient at steep grazing angles, the large geometric  area, and the short range. Range performance is degraded for targets in the sidelobe clutter  region wherever the clutter is near or above the receiver noise level. 
  TK   FROM TIME  TK TO TIME TK  !TK  IS THE TARGET STATE CHANGE DUE TO AN UNKNOWN ACCELERATION  CAUSED BY A MANEUVER OR ATMOSPHERIC DRAG AND  !PTK  IS TARGET STATE CHANGE DUE TO A KNOWN  ACCELERATION THAT CAN BE CORRECTED  SUCH AS GRAVITY FOR A FALLING OBJECT OR #ORIOLLIS ACCELERA 
 References [1] The Second World War 1939-1945 —Royal Air Force, Signals Volume VI —Radar in Maritime Warfare, Air Ministry, 1954 (TNA AIR 10/5555) [2] Lovell B 1991 Echoes of War; The Story of H 2S Radar (London: Taylor and Francis)Airborne Maritime Surveillance Radar, Volume 1 3-19. [3] Burns R 2000 The Life and Times of A D Blumlein (New York: The Institution of Electrical Engineers) [4] H2S Mark II Equipment and A.S.V. Marks IIIA and IIIB, ARI 5153, S.D.0296(1), ch 1, 2nd edn, Air Ministry, Nov 1943 ( www.vmarsmanuals.co.uk/ ) [5] The Performance of Static A.S.V. 
 A target such as  an aircraft, however, will return some energy with the correct polarization as well as energy  with the incorrect polarization. Energy incident on the aircraft may be returned after one  "bounce," as from a plane sheet or a spherical surface; or it might make two or more bounces  between various portions of the target (similar to a corner reflector) before being returned to  the radar. On each bounce the direction of polarization rotation is reversed. 
 The velocity of propagation and  the material losses are included although not the spreading losses. The reason for  this is that the received A-scan would normally have time-varying gain applied   in the receiver and signal processing, and to introduce spreading loss and then com - pensate is an inefficient modeling exercise. In the model only the first reflection is  computed, although multiple internal reflections within each layer will be generated  and a full representation should include these. 
 Although the inverse synthetic aperture  results from relative motion of the target, just as does the cross-section amplitude fluctuations  mentioned previously, the processing of the inverse synthetic aperture radar signal requires a  coherent system (one that preserves phase). In principle, inverse synthetic aperture radar can  be used to image moving targets such as aircraft and ships. It has been applied in the past to  imaging of the moon and to mapping the surface below the clouds surrounding the planet  Ven~s.~'  P~larization.~~.~' The polarization of the radar backscattered energy depends on the target  properties and differs, in general, from the polarization of the energy incident on the target. 
 The ERS SAR instrument was  a subset of a combined radar group, the Active Microwave Instrument (AMI), com - prised of a scatterometer and a wind/wave mini-SAR mode, as well as the SAR itself.   †  The first digitally processed images from the Seasat SAR required 40 hours for a quarter-frame (50 km square)   on a mainframe computer. ch18.indd   8 12/19/07   5:13:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 From radar to target via reflection from the surface and return directly to the radar  (AMB-BA). (This is the opposite of No. 2.)  4. 
                  &)'52%  A  "ANDLIMITED  REAL PASSBAND SIGNAL SPECTRUM BEFORE SAMPLING AND  B  SIGNAL SPECTRUM  AFTER SAMPLING    
 TION IS THE FACT THAT A LARGE TARGET FLYING IN FRONT OF A SMALLER TARGET MAY CAUSE ENOUGH BUILDUP IN THE MAP TO SUPPRESS THE SMALL TARGET /NE WAY TO OVERCOME THIS PROBLEM IN A SYSTEM THAT INCLUDES AUTOMATIC TRACKING  WOULD BE TO USE THE T RACK PREDICTION GATE TO  INHIBIT UPDATING OF THE CLUTTER MAP WITH NEW TARGET  AMPLITUDES Ó°£ÈÊ - 
 147–152. 25. Zhao, Y.; Lin, Y.; Hong, W.; Shen, W.; Xue, F. 
 TO 
 Cheng: Phase Shifter Thinning and Sidelobe Reduction for Large Phased  Arrays, IEEE Trans., vol. AP-24, pp. 139-143, March, 1976. 
 W. D. Blair, G. 
 ,/"  ! NUMBER OF SENSORS CAN BE INTEGRATED RADAR  IDENTIFICATION FRIEND OR FOE )&&   THE AIR TRAFFIC CONTROL RADAR BEACON SYSTEM !4#2"3   INFRARED  OPTICAL  AND ACOUSTIC 4HE SENSORS THAT ARE MOST EASILY INTEGRATED ARE THE ELECTROMAGNETIC SENSORS  IE  RADAR  )&&  AND STROBE EXTRACTORS OF NOISE SOURCES OR EMITTERS &)'52%   #OMPARISON OF DETECTION FUSION AND TRACK FUSION APPROACHES &OR AIR 
 Itisespecially useful inhoming, and intelling plots ofrange and bearing forrecording elsewhere inpolar form. 2.Displays inwhich thedesired angular field ofview issosinall that the distortion can bemade negligible byproper normalization of (u)150-mile sweep, normal PPI with grid (b)100-mile sweep, B-scan, zerodelay. squares. 
 The Role ofthe Receiving System.—It isthe purpose ofthe receiving system toextract the information contained inthe radio- frequency echoes, tosort itinterms ofthe geometrical parameters involved, and topresent the results tothe observer inaconvenient and useful form. The data involved areinavariet yofforms. Most ofthem come from theradar setitself. 
 LOOP ADAPTIVE -4) FOR CANCELLATION OF SIMULTANEOUS FIXED AND MOVING CLUTTER . 
 ERTIES OF THE PROPAGATING MEDIUM 4HERE ARE SOME APPLICATIONS OF '02  SUCH AS ROAD LAYER THICKNESS MEASUREMENT  WHERE THE FEATURE OF INTEREST IS A SINGLE INTERFACE 5NDER SUCH CIRCUMSTANCES  IT IS POSSIBLE TO DETERMINE THE DEPTH SUFFICIENTLY ACCURATELY BY MEASURING THE ELAPSED TIME BETWEEN THE LEADING EDGE OF THE RECEIVED WAVELET PROVIDED THE PROPAGATION VELOCITY IS ACCURATELY KNOWN !LTHOUGH A GREATER DEPTH RESOLUTION IS ACHIEVED IN WETTER MATERIALS FOR A GIVEN  TRANSMITTED BANDWIDTH BECAUSE OF THE REDUCED WAVELENGTH IN HIGH DIELECTRIC MATERIALS  EARTH MATERIALS WITH SIGNIFICANT WATER CONTENT TEND TO HAVE HIGHER ATTENUATION PROPER 
 Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  118     12.1.6  MAMIS -CFAR   L LLLL LLLsamples of the digital signal SUT-TVcomparator target identification. .SUT TVs t r o a g e . .A/2+3 A/2+1 A/2 . 
 Itplots inrectangular rather than inpolar coordinates, contains “smoothing” circuits that greatly improve the accuracy oftheplotted aircraft position, and draws anink record ofthe position ofthe aircraft being tracked, sothat the controller has aknowledge ofthe aircraft course, aswell asposition, at alltimes. Thk device also plots inground range rather than inslant range. The range atwhich aircraft can betracked bythe SCR-584 can be greatly increased, and theaccuracy oftracking somewhat improved, ifan airborne beacon (Chap. 
 Such processing is usually called ADT (automatic detection and track), When the outputs  from more than one radar are automatically combined to provide target tracks, the processing  is called A DIT (automatic detection and integrated track) or IADT (integrated ADT).  A surveillance radar that provides target tracks is sometimes called a track-while-scan  radar. This terminology is also applied to radars that scan a limited angular sector to provide  tracking information at a high data rate on one or more targets within its field of view. 
 The familiar expl.ession  for thernial noise power at rtiicrowave frequencies (No = kT, where k = Boltzmann's constant  arid 7' = absolute tenlperature) does not apply when kT Q It is the coarseness of the laser  signal itself, due to its quantized nature, tliat ultimately sets tlie limit to sensitivity as given by  I:q. (14.3X). 13y settirig k7;, = lrfl an "eqi~ivaletit noise temperature" can be obtained for a laser  receiver. 
      
 A weighting function may be assigned to each patch, and the problem is essentially solved when the amplitude and phase of those functions have been determined. The point of observation is forced down to a general surface patch, whereupon the fields on the left sides of Eqs. (11.9) and (11.10) are those due to the coupling of the fields on all other patches, plus the incident fields and a "self-field." The self-field (or current or charge) is moved to the right side of the equations, leaving only the known incident field on the left side. 
 The buildup of the current by means of this secondary emission process is  very rapid (within nanoseconds). There is little pulse-to-pulse time jitter in the starting process.  All hough the name cold-cathode emission is used to describe the action by which electrons arc  produced in the CFA, the cathode might not actually be "cold." The bombardment of the  cathode surface by returning electrons can raise the cathode temperature high enough to  require liquid cooling to prevent its destruction. 
 SCALE  SHORT 
 The  . 0 7  PICTURE ON THE TUBE “ros  one essential difference between CRT’s used in Types A  and B is that B tubes use intensity modulation. In‘ ™  Type A the echo blip is ‘pulled’ up or down out of its  horizontal trace by voltages applied to the Y plates. 
 PULSE FREQUENCY CHANGE IN MICROWAVE OSCILLATORS IS PRIMARILY CAUSED BY HIGH 
 RIAL DIFFERENCES !MONG THESE ARE THE -/3&%4 -ETAL 
 Whenaradarsystemisoperated underlaboratory conditions byengineer­ ingpersonnel andexperienced technicians, theinclusion oftheabovelossesintotheradar equation shouldgivearealistic description oftheperformance oftheradarundernormal conditions (ignoring anomalous propagation effects). However, whenaradarisoperated underficldconditions. thcpcrformance usuallydeteriorates evenmorethancanbeaccounted forhytheahovelosses,especially whentheequipment isoperated andmaintained byinexper­ iencedorunmotivated personllcl. 
 CONTROLLED TUBE  OPERATING AS CLASS 
 SIDED BANDWIDTH MUST BE  TWICE THE ONE 
 Inf. Sci. 2017 ,60, 060308. 
 SENSING RADAR WAS THE DOWNWARD 
 Suppose that the width ofthe radar beam inazimuth iseffect~vely 1°, and that the ope~ation required isasearch through 360° inaz.inuth by rotation oftheantenna. Clearly, iftheantenna turns atarate exceeding 500° per see, during one revolution some narrow sectors inthe region to becovered will fail tobeilluminated. We therefore conclude that the shortest possible time inwhich the area can besearched is%+$ or0.72 sec. 
 Larson, R. W., et al.: Bistatic Clutter Measurements, IEEE Trans., vol. AP-26, pp. 
 This results in a simpler  system compared to providing a stable base. This is called roll stabilization.  A different approach to the problem is line-of-sight, or tilt, stabilization. 
 Again Eq. (22) correctly expresses theprobability that thepower, inanarbitrary interval, will lie between Pand P+dP. The task ofdetecting asignal amid the noise inthis simplified case amounts toselecting aninterval which displays solarge avalue ofP that one isjustified inbetting that thepeak was due toacombination of signal and noise, and nottonoise alone. 
 OFF ACCELERATION 2ADAR 3CHEDULING  4HE SCHEDULING AND THE TRACKING FUNCTIONS CLOSELY COOPER 
 in  doppler, or with any combination. Almost any radar can be considcrecl a tracking radar.  provided its output information is processed properly. 
 Inmost American tubes a“second grid” atapositive poten- tial ofafew hundred volts serves toattract theelectrons from thesDaceL charge inmuch the same way asdoes the screen grid inanordinary tetrode orpentode. The electrons aregiven their final high velocity by apotential difference ofafew thousand volts maintained between the cathode and ananode formed byaconducting coating ofcarbon (Aquadag) ontheinner surface oftheglass atthescreen end ofthetube. Focusing can beeither electrostatic ormagnetic. 
 1959.  52. Kramer, E.: A Historical Survey of the Application of the Doppler Principle for Radio Navigation,  lEEE 7-rarrs.. 
 If automatic detection, sidelobe cancellation, - - - --1_. or MTI is needed-iFTKe-raar;-ttmemmd-kseparatey employed in each receiving channel,  thus adding to the cost and complexity of the radar. The individual pencil beams, however,  limit the volume of space observed, which can be an advantage in rain clutter or chaff. 
 Ê 
 In spite of its limitations, the VHF air surveillance radar was widely used by the  Soviet Union because it was a large country, and the lower cost of VHF radars made  them attractive for providing air surveillance over the large expanse of that country.8  They have said they produced a large number of VHF air-surveillance radars— some were of very large size and long range, and most were readily transportable.  It is interesting to note that VHF airborne intercept radars were widely used by the  Germans in World War II. For example, the Lichtenstein SN-2 airborne radar oper - ated from about 60 to over 100 MHz in various models. 
 2.2. k-Means Clustering The k-means clustering algorithm attempts to partition pobservations into kclusters such that each observation belongs to the nearest cluster mean (centroid) [ 27]. The k-means algorithm iteratively tries to ﬁnd kcentroids for each cluster, while minimizing a within-cluster sum of squares argmink ∑ i=1∑ xj/epsilon1S/bardblxj−μj/bardbl2, where xjis the jthobservation and μjis the mean point (centroid) in the cluster. 
 The holes correspond,  roughly, lo the inductance L, and the slots correspond to the capacity C. In the desired mode  of operation (the so-called rr mode) the individual C's and L's are in parallel, and the frequency  or the magnetron is approximately that of an individual resonator. The cathode (4) is a fat  cylinder of oxide-coated material. 
 1 L Moore, R. K.: Trade-Off Between Picture Element Dimensions and Non-Coherent Averaging in  Side-Looking Airborne Radar, IEEE Trans., vol. AES-15,, pp. 
 This loss is 1.4 dB for a 3-pulse canceler and 2.1 dB for a 5-pulse canceler,  assuming a large number of pulses. If quadrature MTI channels (see Section 2.13) are  not employed, there is an additional loss of 1½ to 3 dB. The abscissa of these curves, V/VB, represents the ratio of target velocity V to the  blind speed VB = l fr /2, where l  is the radar wavelength and fr is the average PRF of  the radar. 
         . 
 However, these achievements only take the stripmap mode into consideration and further research still needs to be accomplished by considering the sliding spotlight observation geometry. Compared with the stripmap mode, the P-band sliding spotlight SAR system has an ultra-long integration time and more complicated observationgeometry which means a longer exposure time and a longer ionospheric penetration length (IPL)in scintillation active regions. Due to the beam scanning, the incident angle of beam center, which is an important parameter in scintillation simulations, varies within the acquisition time. 
 http://directory.eoportal.org/info_RISATRadarImagingSatellite.html 26. http://directory.eoportal.org/info_TanDEMXTerraSARXaddonforDigitalElevationMeasurement.html 27. http://www.mdacorporation.com/news/pr/pr2006031301.htm 28. 
 Davies41 and Chap. 10 of the "Handbook of Geophysics and the Space Environment"42 can be read for information on ionospheric radio-wave transmis- sion. The radar designer needs a statistical description that will permit matching the design to the required frequency span, power levels, and vertical radiation- angle gain. 
 LIMITED AREA ! P IS   !R C H00 2  PP T A      !S THE PULSE CONTINUES TO IMPINGE AND SPREAD OVER THE SURFACE  THE RESULTING PULSE 
 SHIFT COMPUTATION AND OPERATION  FOR MINIMAL INSER 
 6.14. The charging impedance is  shown as an inductance. The pulse-forming network is usually a lumped-constant delay line. 
 For example, asequential burstofpulsescanbetransmitted atthebeginning ofthetransmission, witheachpulseradiated inadifferent direction. Thisrequires rapidlyswitching phaseshifters tosteerthebeambetween pulses.Italsorequires anapplication whereashortminimum range isnotimportant sincereception cannottakeplaceduringthetransmission oftheburstof. pulses. 
 DC ANDOR DC 
 SIDED BANDWIDTH  POSITIVE FREQUENCIES ONLY  OF A REAL SIGNAL /UR DEFINITION REFERS TO THE TWO 
 DRUM RECORDING EQUIPMENT -!$2%  RADAR  EMPLOYED A SINGLE ANTENNA  DUPLEXED AND USED FOR BOTH TRANSMIT AND RECEIVE  4HIS  
 PULSE DOPPLER RADAR  4.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 where  VR =  radar ground speed  l = RF wavelength  qB = 3 dB one-way antenna azimuth beamwidth, radians  f0 = main-beam depression angle relative to local horizontal, radians  q0 = main-beam azimuth angle relative to the horizontal velocity, radians  t = compressed pulse width  h = radar altitude When the magnitude of the main-beam azimuth angle is greater than half of the azi - muth beamwidth ( | |θ θ0 2 ≥B), the main-beam clutter power spectral density can be  modeled with a gaussian shape with a standard deviation sc = 0.3∆f. Main-beam Clutter Filtering.  In a pulse doppler radar utilizing digital signal  processing, main-beam clutter is rejected by either a combination of a delay-line clut - ter canceler (MTI filter) followed by a doppler filter bank or by a filter bank with low  filter sidelobes, which are achieved via weighting.35 In either case, the filters around  the main-beam clutter are blanked to minimize false alarms on main-beam clutter. 
 For continuous integration, the effective number of independent samples is55 P]T N = - (12.15) 2/[l - ^\RsfMdx o where T'e is the mean envelope power, T is the integration (averaging) time, and Rsf(t) is the autocovariance function for the detected voltage. For many practical purposes, if N is large, it may be approximated by N^BT (12.16) where B is the effective IF bandwidth. For the effect of short integration time, see Ref. 
 This is, in faulty  apparatus, a very common radar effect, and is cured, as  we shall see later, by adjusting the resistances, con-  densers, or other circuit values which result in the CRT  electron beam being pulled across the tube. When we  have the whole thing nicely set up, with Cal pips evenly  spaced, we say we are working ‘on a linear time-base,’  which simply means that if we drew a graph of time  against speed of the electron beam the result would be a  straight-line figure,  At this stage it is worth deviating for a moment to  consider some other familiar radar expressions and  tricks. The display so far described is, as we can see, 2  rather primitive one. 
 WATER CONTENT AND CAN PROVIDE USEFUL INFORMATION FOR THE DETECTION OF SUCH PHENOMENA AS HAIL  IN ACCORDANCE WITH THE DUAL 
 FIG. 16.1 E-2C airborne early-warning (AEW) aircraft showing rotodome housing the antenna. problems to the designer of airborne MTI systems. 
 J. Aerosp. Sci. 
 The roll data from a stable vertical can be applied to the basic roll axis without  the need for computer orders as required in the other two.axis mounts. The antenna is then  stabilized about the azimuth axis if the pitch angle is small.  The three-axis mount of (e) can provide full hemispheric coverage. 
 73, pp. 205–227,  February 1985. 18. 
 It has low spike-leakage, and can handle high peak and average powers. The  flat-leakage power passed by the multipactor is high enough to require a passive diode limiter  following the multipactor. The multipactor has the disadvantage of being complex, and it  offers no protection if the power is turned off. 
 103] ELECTRON ORBITS AIVD THE SPACE CHARGE 331 anode segments. Inaddition, theelectron ispart ofaspace charge with extreme variations indensity. The resulting eIectron motion presentsa problem ofextreme complexity, and adetailed theory has not been developed. 
 CALLY SIMILAR  MIGHT BE VIOLATED ! GOOD RULE OF THUMB IS TO USE ENOUGH REFERENCE CELLS SO THAT THE #&!2 LOSS IS BELOW  D" AND AT THE SAME TIME NOT LET THE REFERENCE CELLS EXTEND OVER A RANGE INTERVAL THAT VIOLATES THE HOMOGENOUS BACKGROUND ASSUMPTION 5NFORTUNATELY  FOR A SPECIFIC RADAR THIS MIGHT NOT BE FEASIBLE )F THERE IS UNCERTAINTY ABOUT WHETHER OR NOT THE NOISE IS 2AYLEIGH 
 The larger the number of elements (MN) in ti1e array, the smaller will he lhc spurious  radiation for a given error tolerance and a given design sidelobe level. In other words, lower  sidelobes are more likely to be achieved with larger antennas. This comes about because the  intensity of the main beam increases as the square of the number of elements (M N)2, while  the spurious radiation increases only linearly since it represents the inc~herentJaddition of  many contributions. 
 ABSORBING MATERIALS 2!-  IS TO ABSORB THE INCIDENT RADAR ENERGY SO AS TO MINIMIZE THE ENERGY SCATTERED BACK TO THE RADAR "OTH METHODS HAVE ADVANTAGES AND DISADVANTAGES 2ADAR !BSORBERS  4HE PURPOSE OF THE RADAR ABSORBER IS TO ATTENUATE INCIDENT  ENERGY AND THEREBY REDUCE THE ENERGY SCATTERED OR REFLECTED BACK TO THE RADAR -OST ABSORBERS ARE DESIGNED TO REDUCE SPECULAR REFLECTIONS FROM METALLIC SURFACES  BUT STEALTH TECHNOLOGY HAS SPAWNED THE DEVELOPMENT OF NONSPECULAR ABSORBERS INTENDED PRIMARILY TO SUPPRESS ECHOES DUE TO SURFACE TRAVELING WAVES 4HE SIMPLEST SPECULAR ABSORBER IS THE  3ALISBURY SCREEN  WHICH IS A THIN RESISTIVE  SHEET MOUNTED A QUARTER WAVELENGTH ABOVE THE METAL SURFACE TO BE HIDDEN FROM A RADAR  4HE DESIGN WORKS BEST FOR INCIDENCE NORMAL TO THE SHEET  AND IF IT CAN BE MANU 
 The standard a-/1 tracker docs not handle the maneuvering target. However, an adaptive  'Y.-/1 tracker is one which varies the two smoothing parameters to achieve a variable bandwidth  so as to follow maneuvers. The value of ex. 
 Thus the ability to radiate  large power by using a trans~nitter at each element is lost in this configuration.  Parallel-plate feeds. A folded pillbox antenna (Fig. 
 r,=time ofriseofvoltage WIV.2 7,=delay time foronset ofosciilatione ro=width ofcurrent andr-fpulse rf=time offallofvoltage wave. and duration ofthe r-fpulse closely approximate etboseoftbecurrent pulse; thevoitage pulse isless steep and oflonger duration. The pulse length, r,,may bedefined asthe interval oftime during which the load current wave iswithin 50percent ofpeak value. 
 F. Harris, “On the use of windows for harmonic analysis with the discrete Fourier transform,”  Proc. IEEE , vol. 
 RADAR ANTENNAS 233  Another property of the radiation patterns illustrated by Table 7. l is that the antennas  with the lowest sidelobcs (adjacent to the main beam) are those with aperture distributions in  which the amplitude tapers to a small value at the edges. The greater the amplitude taper, the  lower the sidclobc level but the less the relative gain and the broader the bcamwidth. 
 (9.6); (2) in addition to spatial filtering, doppler filtering is performed to cancel clutter and chaff; and (3) the radar platform is moving as in airborne and shipborne ap- plications. The detection probability P0 for the optimum filter of Eq. (9.6) is:40 P0 = Q (Vs1M-1S*, V2 In \IPFA ) (9.7) where Q ( . 
 Sensors 2019 ,19, 213 13. Madsen, S. Estimating the Doppler centroid of SAR data. 
 2s4. The Radar Equation. -With thepertinent quantities defined itis now asimple matter toformulate theradar equation. 
 However,  the backward-tracking algorithms can operate in more ambiguous situations (where  the density of false alarms, l, is comparable to or greater than lF or lP). Under these  ambiguous circumstances, the forward tracker will have multiple detections in a  track formation or promotion gate and will require multiple hypothesis to reliably  form tracks. The design of the track formation process and the automatic detection process  should be considered together. 
 WAVE PROPAGATION  AND USE IT TO COMMUNICATE OVER  LONG DISTANCES 4HE TARGETS FOR SUCH (& RADARS MIGHT BE AIRCRAFT  SHIPS  AND BALLISTIC MISSILES  AS WELL AS THE ECHO FROM THE SEA SURFACE ITSELF THAT PROVIDES INFORMATION ABOUT THE DIRECTION AND SPEED OF THE WINDS THAT DRIVE THE SEA 6(&  TO  -(Z   !T THE BEGINNING OF RADAR DEVELOPMENT IN THE S   RADARS WERE IN THIS FREQUENCY BAND BECAUSE THESE FREQUENCIES REPRESENTED THE FRONTIER  OF RADIO TECHNOLOGY AT THAT TIME )T IS A GOOD FREQUENCY FOR LONG RANGE AIR SURVEILLANCE  OR DETECTION OF BALLISTIC MISSILES !T THESE FREQUENCIES  THE REFLECTION COEFFICIENT ON SCATTERING FROM THE EARTHS SURFACE CAN BE VERY LARGE  ESPECIALLY OVER WATER  SO THE CONSTRUCTIVE INTERFERENCE BETWEEN THE DIRECT SIGNAL AND THE SURFACE 
 The ﬁrst and second step establish the process for the sub-aperture method. The full-aperture is divided into k(k=1, 2,···,n.)sub-apertures with the same width θw. There is a trade-off when we choose the width θw. 
 Thisiscommonly called ground-wave propagation. Aground-wave radarcandetectthesamekindoftargetsascana sky-wave radar.Detection issomewhat easierthanwithsky-wave propagation sinceiono­ spheric e~ectsarenotpresentandclutterreturnsfromauroragenerally canb~)eliminated by timegating.Theground-wave radarhasafarshorterrangethancanbeobtained viaskywave because ofthepropagation losswhichincreases exponentially withrange.Aground-wave radarofasizeandfrequency comparable tothesky-wave radardiscussed intheabovemight havearangeagainstlow-altitude aircrafttargetsofperhaps 200to400km. Themicrowave radarthatusestheover-ocean evaporative duct(Sec.12.5)toobtain extended propagation todetectlow-altitude orsurfacetargetsbeyondthenormallineofsight isalsosometimes calledanover-the-horizon radar.Itshouldnotbeconfused withtheHF radarsdescribed inthissectionthatoperate atmuchlowerfrequencies andatmuchlonger ranges. 
 10.8] LOAD REQUIREMENTS 365 totally wasted, but stray load capacity seriously affects time offalland back-swing. Short, well-spaced leads and alow-capacity magnetron fila- ment transformer arehelpful inreducing load capacity. The definition ofpulse duration isintimately bound upwith mag- netron behavior. 
 R. (ed.): "Ferrite Control Components, vol. 2. 
 APPARENT 
 PGAP-1,  pp. l 13-122, February, 1952.  130. 
 13.17] RESOLVED-CURRENT PPI 539 touse them foroff-centering; therefore, when this isdesired, separate coils areprovided onthesame form. Since they areinductively coupled tothesweep coils, thenumber ofturns intheoff-centering coils must also belimited. Off-centering istherefore expensive incurrent, and its extreme amount isusually limited tonot more than two tube-radii. 
 IRE, vol. 21, pp. 475-492, March, 1933. 
 I. Monopulse Radar," Artech House, Inc., Dedham, Mass., 1974 (a  collection of 26 reprints from the literature of monopulse radar).  19. 
 £È°£n  2!$!2 (!.$"//+  &)'52%     &ADING FOR SUCCESSIVE PULSES  OF A MOVING RADAR WITH GROUND TARGET .   '2/5.$ %#(/  £È°£  .04 X 42XDXE 4 
 The data take-offs area 2-phase sine-wave generator forthe spin angle and apotentiometer forthenod angle, both being mounted onthe main gear case toobviate theneed ofslip rings. The gear case isunusual in airborne practice inthat itisoil-filled. Two r-frotary joints arerequired, one onthe spin axis and one onthenod axis. 
 A solid-state circulator is sometimes used to provide further isolation between the transmitter and the receiver. Antenna. The transmitter power is radiated into space by a directive antenna which concentrates the energy into a narrow beam. 
 Delta-sigma converters differ from conventional  Nyquist rate converters by combining oversampling with noise-shaping techniques to  achieve improved SNR in the bandwidth of interest. Noise shaping may be either low- pass or bandpass depending on the application. Delta-sigma architectures provide poten - tial improvements in spurious-free dynamic range (SFDR) and SNR over conventional  Nyquist converters where tight tolerances are required to achieve very low spurious  performance. 
 49, pp. 80-83, July-Aug., 1964.  32. 
 10.Schelkunoff, S.A.,andH.T.Friis:"Antennas, TheoryandPractice," JohnWiley&Sons,Inc.,New York,1952. II.Smith, R.A.:"Aerials forMetreandDecimetre Wave-lengths," Cambridge University Press. London. 
   3INE 
 Where wide percent - age bandwidth and fast settling is required, the most common technique is to cascade a  series of frequency doublers or low order multipliers. This type of multiplier can also  provide near ideal phase noise performance, but has significant phase modulation as a  function of frequency as it contains filters between each stage of multiplication. Predistortion of the multiplier input waveform is often used in order to produce  wideband chirp waveforms with low range sidelobe performance. 
 78.Saxton,J.A.:TheInfluence ofAtmospheric Conditions onRadarPerformance, 1.Inst.Navigation (London), vol.11,pp.290-303, 1958. 79.Schneider. A.B.•andP.D.L.Williams: Circular Polarization inRadars,RadioWIdEla/ronk Engineer, vol.47,no.1/2,pp.11-29.January/February, 1976. 
 101. Glaser, J. I.: Bistatic RCS of Complex Objects Near Forward Scatter, IEEE Trans., vol. 
 Increasing the CRT diameter does not  necessarily help, since the spot diameter varies linearly with the screen diameter. Another  limitation is the dynamic range, or contrast ratio, of an intensity modulated display which is of  the order of 10 dB. This might cause blooming of the display by large targets so as to mask the  blips from nearby smaller targets. 
 6.8. The  tllriirig piston can be positio~ied meclianically from outside the vacuum by means of a vacuum  bellows. This tuning mechanism may be adapted to provide narrowband frequency agility at a  rapid tuning rate for frequency-agile radar. 
 (a) (b) (c) Fm. 10.3.—Magnetron anodeblock. (a)Slot-type magnetron. 
 3.M O    MF    WHERE 3. O IS THE 3.2 AT THE OUTPUT OF A FILTER WITH FREQUENCY RESPONSE  (  F    AND   3. MF IS THE MATCHED FILTER 3.2 4HE FILTER MATCHING LOSS CAN ALSO BE EXPRESSED AS   ,%. 3.M O        WHERE THE MATCHED FILTER 3.2 IS GIVEN BY  3. MF   %.  4HE FILTER MATCHING LOSS IS  q   WHERE  ,M    FOR THE MATCHED FILTER 4HE FILTER MATCHING LOSS EXPRESSED IN DECIBELS  IS ,MD"    LOG,M  AND EQUALS  D" FOR THE MATCHED FILTER     !N ALTERNATE DEFINITION OF SIGNAL 
 A4-pulsedigitalcanceller isemployed withvariableinterpulse periodstoproduce acalculated MTJimprovement factorof39dB.Thepulserepetition frequencies rangefrom310to 360Hz. TheARSR-3 contains provision forswitching inoroutvariousprocessing features. A range-azimuth generator (RAG)permitstheselection tobemadeonthebasisofbothrange andazimuth. 
  
 (/2):/. 2!$!2   Óä°xx LOCAL REAL 
 AP-26(6), pp. 801–804, November 1978.  99. 
 Aslam, “Radar spectral observations of snow,” Dig.  IGARSS ’81 , pp. 654–668, 1981. 
 24, no. 2,   pp. 156–170, March 1988. 
 L. MacArthur, D. W. 
 SPEED AIRCRAFT PLATFORM ,ASTLY  THE !%3! REQUIRES A VERY SIGNIFICANT POWER SUPPLY  0OWER SUPPLIES HAVE  A HISTORY OF BEING HEAVY  HOT  AND UNRELIABLE %VEN THE BEST SYSTEMS STILL HAVE OVERALL POWER EFFICIENCIES PRIME POWER IN TO 2& OUT IN SPACE  IN THE n REGION IN SPITE OF YEARS OF DEVELOPMENT 4HE TYPICAL !%3! REQUIRES LOW VOLTAGE AND HIGH CURRENT AT THE 42 CHANNEL 4HIS FORCES LARGE CONDUCTORS IN THE ABSENCE OF HIGH POWER LIGHT 
 $ RADARS v  * !TMOS /CEAN 4ECHNOL  VOL   PP n     # &RUSH  2 * $OVIAK  - 3ACHIDANANDA  AND $ 3 :RNIC  h!PPLICATION OF THE 3: PHASE CODE  TO MITIGATE RANGE 
 W. Bordner, “Synthesis of an optimal set of radar track-while-scan filtering  equations,” IRE Trans ., vol. AC-7, pp. 
 waves. and does not block the aperture. Some aperture  blocking by the feed does occur, but this 'can be made small. 
 The optimization algorithms obtain phase error via image quality evaluation. The image contrast and entropy are maximal and minimum respectively when the image are well-focused. The scatter-based algorithms are higher computational efﬁciency than optimization algorithms, but the image quality constructed with former algorithms are worse than latter algorithms results. 
 492 INTRODUCTION TO RADAR SYSTEMS  10  0  ID  ~ -10  0 b  0  <U 0 -20  ·c ::,  ~ 0.  C -30 .Q  ~  "' V)  "' e -40 u  -50  -60  10  10  0  m .:g-10- 0  b  0  f  0 -20 e :,  t a.  C -3Q Q  t;  <U  "'  ~ -40 -u  -50 Delaware Boy  50  Phoenix 10°  Grazing angle  (al  Arizona mountainous  Arizona deser I ,..,___.~i::;::ci;;::;,;;:,,-­ N. 
 (/2):/. 2!$!2   Óä°ÇÎ CAN BE FOUND IN &IGURE    WHICH COMPARES '27!6% PREDICTIONS WITH EXPERIMEN 
  COS PI COS PS  
 The tubing has aninside diam- eter of~in. The total signal delay is1000 ~sec. The carrier frequency is15Me/see, and thepulse length is~psec. 
  
 Practical experiences indicate that the resolution limit is determined rather more by  implementation and environmental factors than by the pure JNR considerations. 24.7 TRANSMITTER-RELATED ECCM The different types of ECCM are related to the proper use and control of the power,  frequency, and waveform of the radiated signal. One brute-force approach to defeat  noise jamming is to increase the radar’s transmitter power. 
 10.37, in order toprovide theright amount ofcoupling between coils. The appro- priate value ofinductance ateach end oftheline differs slightly from that inthemiddle sections. Ithas been found practically that theoptimum number ofmeshes isrelated tothe desired pulse length asshown inthe following table. 
 SUPPORTED 4HE MOST COMMON RIGID RADOME 
 - 2ADAR HEADS FOR PORT CONTROL AND COASTAL SURVEILLANCE SYSTEMS HAVE SOME REQUIREMENTS  IN COMMON WITH THOSE FOR SHIPBORNE RADARS 4HIS ORIGINALLY RESULTED IN MANY OF THE WELL 
 MENT AND A SIGNAL BANDWIDTH  RF (Z   THERE WILL BE APPROXIMATELY  RF4 INDEPENDENT  SAMPLES OF THE SQUARE OF THE SIGNAL ENVELOPE )T FOLLOWS  THEREFORE  THAT FOR THE HIGH 3.2 CASE AN ESTIMATE OF THE MEAN POWER FOR THIS PROCESS  }0 R WILL HAVE A VARIANCE OR  MEAN SQUARE ERROR GIVEN BY   VAR} 00 4RR Fy S    3UBSTITUTING FOR  RF FROM THE EXPRESSION  RF   RVK  WHERE  RV IS THE WIDTH OF THE  DOPPLER SPECTRUM  %Q  BECOMES   VAR} 00 4RR VyL S     4HIS EXPRESSION IS VALID FOR HIGH SIGNAL 
 Control-electrode heating can therefore be a limitation on the maximum PRF that may be used. In practice, dc operation has seldom been used23 because it requires a much larger capacitor bank to limit droop (as opposed to using a switch tube in the constant-current mode) and because an arc in a de-operated CFA requires crowbarring (Sec. 4.9), which interrupts operation for a few seconds instead of only for a single pulse; it has not been possible to make CFAs arc-free. 
 PROPAGATION OF RAI3AR WAVES 455  focusing can change the re!ative amplitltdes of the two components. The focusing effect can  eyen cause the arnplitude of the surf;ice-reflected ray to sometimes exceed that of the direct  ray.JR Tlie effect of tlie duct on the title-of-siglit propagation is to reduce the angle of the lowest  lobe, br-ingtng it closer to tlie surface.  Consequences of ducted propagation. 
 ª «­ ¬­¹ QF QFº º­ »­    )T  CAN BE NOTED THAT THE NUMERATOR OF THE FUNCTIONAL 5 P  E  IS THE SQUARED ADAPTED  OUTPUT \      \  3( DQF;;-6 
 414INTRODUCTION TORADAR SYSTEMS Theambiguity diagram inthreedimensions maybelikenedtoaboxofsand.Thetotal amount ofsandintheboxisfixedandcorresponds toafixedsignalenergy.Nosandcanbe added,andnonecanberemoved. Thesandmaybepiledupatthecenter(origin)toasnarrow apileasonewouldlike,butitsheightcanbenogreaterthanafixedamount(2£)2.Irthesand inthecenterisintoonarrowapile,thesandwhichremains mightfinditselfinoneormore additional piles,perhaps asbigastheoneatthecenter. Theoptimum waveform isonewhichhasthedesiredambiguity diagram foragiven amountof"sand"(energy). 
 An FIR filter with one delay is a two-pulse  filter. For feedback (IIR) filters, it is inappropriate to call them two-pulse (or three-pulse, etc.) filters because they   require a number of pulses to reach steady-state.FIGURE  2.30  Comparison of MTI improvement factor of binomial-weight  MTI and optimum MTI against a gaussian-shaped clutter spectrum ch02.indd   33 12/20/07   1:44:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 BellSys.Tee".J.•vol.18. rr.222-234. 1939. 
 For O '# O. the beam shape is not symmetrical about the center of the beam, but is  eccentric. Thus the beam direction is slightly different from that computed by standard for­ mulas. 
 VIA is shown in ﬁgure 4.8. The various units are described in more detail below. 4.3.1 Scanning unit, type 68 The lock –follow facility incorporated a new scanner, type 68, which replaced the type 67 used in ASV Mk. 
 122.Kay,A.F.:Radomes andAbsorbers, chap.32of"Antenna Engineering Handbook," H.Jasik(ed.), Mc(jraw-Hill BookCompany, NewYork,1961. In.Dicaudo, V.J.:Radomes, Chap.14of"RadarHandbook," M.I.Skolnik (cd.),McGraw-Hili Book Co.,NewYork.1970. 124.Walton, J,R.,Jr.:"Radome Enginccring Handbook," MarcelDekker, Inc.,NewYork,1970. 
 ALLY NAMED  &AST 4IME #ONSTANT &4#  4HE TIME CONSTANT OF THE DIFFERENTIATOR IS OPERA 
 Some radars operate in a  search, or acquisition, mode in order to find the target before switching to a tracking modt.  Although it is possible to use a single radar for both the search and the tracking functions, such . TRACKING RADAR 153  a procedure usually results in certain operational limitations. 
 ® 2ADAR TRACKING OF TARGETS IS PERFORMED BY USE OF THE ECHO SIGNAL REFLECTED FROM A TARGET ILLUMINATED BY THE RADAR TRANSMIT PULSE 4HIS IS CALLED  SKIN TRACKING TO DIFFERENTIATE  IT FROM BEACON TRACKING   WHERE A BEACON OR A TRANSPONDER TRANSMITS ITS SIGNAL TO THE  RADAR AND USUALLY PROVIDES A STRONGER POINT 
 BAND BAND BANDAPPARENT RELATIVE DIELECTRIC CONSTANT €r . Surface descriptions suitable for use in mathematical models are necessarily greatly idealized. Few natural grounds are truly homogeneous in composition over very wide areas. 
 Both criteria of ship01 have been greatly improved in Figure 8, and the focusing of the ship01 image is enhanced, while the criteria change of ship02 are not as obvious as for ship01 and the enhancement in refocusing of ship02 is not as good as for ship01.      (a) (b)  Figure 8. The entropies and IC values convergence of two sub-images versus the number of iterations. 
 High-frequency  transistor design is concerned with optimizing the physical parameters that contribute  to the time-delay components.10 ch11.indd   10 12/17/07   2:25:26 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 
 SENSITIVE PHASE AND AMPLITUDE PERTURBATIONS AT THE APERTURE )N GENERAL  THESE PERTURBATIONS WILL BE DIFFERENT FOR THE MONOPULSE SUM AND DIFFERENCE PATTERNS  SO THAT ONLY A COMMON AVERAGE CAN BE COMPENSATED BY CALIBRATION.   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°{Ç 3ERIES &EEDS &IGURE  SHOWS SEVERAL TYPES OF SERIES FEEDS )N ALL CASES EXCEPT  D    THE ELECTRICAL PATH LENGTH TO EACH RADIATING ELEMENT HAS TO BE COMPUTED AS A FUNCTION  OF FREQUENCY AND TAKEN INTO ACCOUNT WHEN SETTING THE PHASE SHIFTERS 4YPE  A IS AN END 
 A useful  figure of merit is the integrated sidelobe ratio (ISLR), defined as3  ISLR =IntegraloverPSFSidelobes Integralove erPSFMainlobe (17.34) ISLR is usually measured in dB; a typical value might be −20 dB. Low ISLR is  clearly desired. Multiplicative Noise Ratio (MNR). 
 The sandwich construction also provides a greater variety ofwall construction forhigh strength and efficient elec- trical transmission. The approach tothe structural design problem will depend upon the shape ofthe radome and the pressure distribution. These two factors. 
 2.15. Attenuation ofMicrowaves inthe Atmosphere.—The earth’s atmosphere, excluding the ionosphere, isfor all practical purposes transparent toradio waves offrequency lower than 1000 llc/sec. Even over atransmission path hundreds ofmiles long noappreciable fraction oftheenergy intheradio wave islost byabsorption orscattering inthe atmosphere. 
 BASED WAVEFORM IS  GIVEN AS   FT " T4 4 T 4   TAN   TAN 
 FREE  PART OF THE DOPPLER BAND )F THE TARGET FALLS  IN THE SIDELOBE CLUTTER REGION  THE RANGE PERFORMANCE WILL BE DEGRADED  SINCE THE TOTAL INTERFERENCE POWER SYSTEM NOISE PLUS CLUTTER  AGAINST WHICH THE TARGET MUST COMPETE IS INCREASED 4HE FOREGOING DISCUSSION CAN BE APPLIED TO THE SIDELOBE CLUT 
 AMPLIFIER THAT UTILIZES SEVERAL RESONANT  CAVITIES OR A TRAVELING WAVE CIRCUIT TO OPERATE AS AN AMPLIFIER 4HE GYRO 
 34_Harrison. 1\_:Marine RadarToday-A Review. TileRadioarIdElectrollic Ellgill(.'('/'. 
   PP n     $ 2 ,YZENGA  ! , -AFFETT  AND 2 ! 3CHUCHMAN  h4HE CONTRIBUTION OF WEDGE SCATTERING TO  THE RADAR CROSS SECTION OF THE OCEAN SURFACE v )%%% 4RANS VOL '% 
   
 (It does degrade the improvement factor  of clutter signals received from ambiguous ranges, but for the TDWR operation, that  degradation was deemed acceptable.) Environmental Considerations.   This discussion contains essential informa - tion for those designing a modern surveillance radar to detect man-made airborne  targets. The laws of physics combined with the environment make it impossible to  design an MTI surveillance radar that does not have compromises. 
 L.: Advances in Klystron Amplifiers, Microwave J., vol. 16, pp. 33-36, 39, December, 1973. 
 Pettengill, P. G. Ford, W. 
 RESONANT  WAVE FREQUENCY. Óä°În  2!$!2 (!.$"//+  /CEAN CURRENTS CAN BE DETERMINED WHEN A ZERO DOPPLER REFERENCE SUCH AS AN ISLAND   IS IN THE RADAR FOOTPRINT 4HE ./!! 7AVEWATCH WEBSITE PROVIDES ACCESS TO  ARCHIVED MAPS OF SIGNIFICANT WAVEHEIGHT  DOMINANT WAVE PERIOD   AND OTHER PARAM 
 Aeff = effective area contributing to multiple internal reflections 3. A = actual area of the plate 4. a = mean radius of curvature; L  = length of slanted surface 5. 
 (21.32) are those corresponding to a geometric progression, the sum term can be immediately evaluated. The result is ^ ,. ,2/™ sin [(N + \)4irx'vTl2\RdJ = ,,1(2(00/C)A:' /2RQ LV i Tl O\ -l-n Z sin [4™t'v772X*0] The right-hand side of Eq. 
 The following references (2 to 8) appear in IRE Trans., vol. IT-6, no. 3, June, 1960, special issue on  Matched Filters:  2. 
 In Proceedings of the International Conference on Synthetic Aperture Sonar and Synthetic Aperture Radar, Lerici, Italy, 13–14 September 2010; pp. 174–180. 11. 
 The upper corners of the antenna aperture have a square rather  than rounded outline. This causes the underside of the elevation beam to have a sharp drop-ofT  which minimizes the ground-reflected energy that causes a lobed elevation pattern and a  degradation of the rain-rejection capability of circular polarization. The azimuth resolution  and accuracy obtained by the 1.25° beamwidth is said to be 2° and 0.2°, respectively.46 The  antenna can be housed in a 17.4 m (57 ft) diameter rigid geodesic-radome. 
 Atw~stage limiter isused ahead ofthe i-fdiscriminator, care being exercised toprovide sufficiently rapid limiting action toreduce impulse noise. The discriminator issimilar tothat used inradar AFC circuits and has abandwidth ofabout 17Me/see between peaks.. 726 RADAR RELAY [SEC. 
 Krichbaum: " Radar Cross-Section Handbook," (2  vols.), Plenum Press, New York, 1970.  20. Siegel. 
 !          Figure 3. 
 LARLY SPACED  SIDELOBES THAT ARE POINTING TOWARD STRONG NOISE SOURCES 3PATIALLY ADAP 
 Therefore if the pulse power Pt is the power of the long (uncompressed) transmitted pulse, then T must be the duration of that pulse. A further advantage of this form of the equation, or more specifically of the definition of the detectability factor, is the indicated dependence of the radar de- tection range on the integration of successive pulses, if any, that takes place in the receiving system. Integration is discussed in Sec. 
 AVERAGE POWER 7 
 BEAM AND PROVIDE DEGREES OF FREEDOM TO ALLOW FOR MOTION COMPENSATION IN THE ARRAY MAIN 
 Properly designed, however, a cylinder fed by an offset multiple-element line source can have excellent performance18 (Fig. 6.10). A variation on this design has the axis of the reflector horizontal, fed withfsec2 ^2 tan O f tan B . 
 Among these bright signals are weaker signals, some ofthem too faint toshow onthe screen. The resulting stippled or “beaded” texture ofground return isclearly visible when fast sweeps areused, asinFig. 3.25. 
 3CREENING *AMMER 34!0 3PACE 
 The intrinsic region acts as a slightly lossy  dielectric at microwave frequencies and the heavily doped regions are good conductors.  When biased in the reverse (nonconducting) state, the PIN diode resembles a low-loss capaci­ tor. It is essentially an insulator situated between two conductors and exhibits the parallel­ plate capacitance determined by the dielectric of the intrinsic region. 
 Some idea ofthemagnitudes involved inthereceiver problem can be obtained from Table 16.4. The fluctuations due tothe wind were TABLE 164.-FLUCTUATIONS DUE TOW’IND AND SCANNING h, cm 9.2 9.2PRF 500 2000Beam- width, degrees 1 3Scanning Pulses per rate, beam- rpm width 4 21 4 250Wind effect IScanning effect rms fluctuation rms fluctuation rms total echo’ rms total echo’ db dh –34 I–22 –46 –44 obtained from Table 16,2 for wooded terrain and awind velocity of 25mph. The scanning effect was derived from theformula forextended clutter inSec. 
 A high duty cycle, 0.333 to 0.5, may be used. Range R can then be calculated by ^fRR= - — (17.10) /R This method of range measurement has poor accuracy because of the errors involved in measuring the derivatives. An advantage of this technique is that the target return is never eclipsed by the transmitter pulse, thus improving tracking. 
 ORBITING AND PLANETARY SYSTEMS 4HE MATERIAL IN  THIS CHAPTER IS DESIGNED TO BE REASONABLY COMPLETE AT A SURVEY LEVEL THE DISCUSSION ZOOMS IN ON SELECTED CASE EXAMPLES TO ILLUSTRATE APPLICATION 
 Absolute beam-pointing accuracies to within less than one-fiftieth of a  (scanned) beamwidth have been measured with scans up to 60 °.20 The accuracy is  limited by phase and amplitude errors. Since phase shift rather than time delay is  used, as the frequency is changed, the direction of the null of the scanned beam is also  changed, and the beam moves toward broadside with an increase in frequency . Shaped Beams . 
 VI. It was reported that the sensitivity of ASVMk. III was quite variable over the trials, ranging from 19 nmi to 29 nmi, representing a variation of about 7.5 dB. 
 Less  attcntuation is applied to the higher frequencies, where the echo signals are weaker.  The echo signal from an isolated target varies inversely as the fourth power of the range,  as is well known from the radar equation. With this as a criterion, the gain of the low­ frequency amplifier should be made to increase at the rate of 12 dB/octave. 
 By September, ranges greater than 40 miles were obtained on bomber aircraft. The  frequency was 12 MHz. Also, in that month, the first radar measurement of the height of  aircraft above ground was made by measuring the elevation angle of arrival of the reflected  signal. 
 Detailed definitions of these and other range- equation factors are given in Sees. 2.3 to 2.7. Maximum-Range Equation. 
 Instead, a brief review will be given of  the various Tadar-ECCM options that can make the task of ECM more difficult.  As a general rule, good radar design practice can reduce vulnerability to electronic  countermeasures. Good design is based on maximizing the ratio of the signal energy to noise  power per hertz tE/ N 0), as well as employing techniques to reduce mutual interference. 
 Early radar theories for ground return assumed, as in optics, that many targets could be described by a Lambert-law variation of intensity; that is, the differential scattering coefficient varies as cos2 6, with 9 the angle of incidence. This "perfectly rough" assumption was soon found wanting, although it is a fair approximation for the return from many vegetated surfaces over the midrange of angles of incidence. Clapp10 described three models involving assemblies of spheres, with dif- ferent spacings and either with or without a reflecting ground plane. 
 -   3 3TEIN AND * * *ONES  h-ODERN #OMMUNICATION 0RINCIPLES WITH !PPLICATION TO $IGITAL  3IGNALING v .EW 9ORK -C'RAW 
 Shadowing.  The possibility of shadowing must be considered seriously whenever  the sea is viewed at grazing angles smaller than the rms slope angle of the sea surface.  Some examples were discussed earlier in connection with the behavior of sea clutter at  low grazing angles in Figure 15.13. 
 ”Beacon local oscillator and beacon AFC areincluded where beacon reception isrequired. Insmaller radar sets, the modulator network and switch tube and even the modulator power supply may beput with ther-funit. Anextension ofthis trend leads to anarrangement with allparts ofthe radar except the controls and the indicator tube inasingle container. 
 Huang, M. Highway Engineering Materials Rheology ; Southwest Jiaotong University Press: Chengdu, China, 2010. 30. 
 OUTPUT DEPENDENCE ON ECHO AMPLI 
 Radar System Engineering  Chapter 12 – Selected Radar Applications  142        Figure 13.10  ACC Radar sensors for highway and street traffic (Courtesy A.D.C.).     Since then the frequency range from 76 GHz to 77GHz has been licensed in Europe, the USA  and in Japan (Technical Standard EN301091 V1.1.1, ETSI) for the use in ACC.  The first s e- ries installation took place with the S -class from Mercedes at the beginning of 1999. 
 Round and Cut Paraboloid Antemas.-One very common type ofmicrowave radar antenna takes the form ofaparaboloidal reflector 1 with asource ofradiation, or“antenna feed, ”atitsfocus. Since the /+’ FIG. 9.2.—RaY diagram ofa paraboloid antenna.wavelength ofthe radiation isshort incom- parison with thedimensions ofthereflector, it isprofitable inanintroductory discussion to regard the operation oftheantenna asaprob- lem inray optics (Fig. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers.  RADAR RECEIVERS  6.396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 This can be achieved with rms input noise ( s ) equal to the LSB step size ( Q). 
 Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 1.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 is made. To account for these added signals, the numerator of the radar equation is  multiplied by a factor nEi(n), where Ei(n) is the efficiency in adding together n pulses. 
 This was almost a year sooner than the successful NRL experiments with pulse  radar. By September, ranges greater than 40 miles were obtained on bomber aircraft. The  frequency was 12 MHz. 
 15.8) or Eq. 15.9, with an error that is usually only 1 or 2 dB. Clutter Statistics. 
 Thefrequency of ASV Mk. I on 214 Mc/s had been causing interference with naval rotating beacons and it was decided to use 176 Mc/s. E K Cole and Pye Radio were contracted to design and develop equipment to the new speci ﬁcation, with an initial order for 4000 sets (an enormous number for a radar, by modern standards). 
 AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 is somewhat more difficult to implement; consequently, the mean deviate defined by  σ µ= ∑− A xi| ˆ| (7.15) is sometimes used because of its ease of implementation and because it is more robust.  It should be noted that the CFAR loss associated with a two-parameter threshold is  larger than those associated with a one-parameter threshold (see Table 7.1), and for  that reason, a two-parameter threshold is rarely used. FIGURE 7.16  Curves of probability of detection versus signal-to-noise ratio for the cell- averaging CFAR, ratio detectors, log integrator, and binary integrator: Rayleigh, pulse-to-pulse  fluctuating target, N = 6, 2 m = 16 reference cells, and Pfa = 10−6 (from G. 
 Short-radius bends are well matched ifthe length along the center ofthe guide ishalf aguide wavelength. Such elbows asthose shown inFig. 11“1lc,are produced byelectrof orming—that is,plating copper orother metal onasoft metal mold which islater melted out. 
 6.9SOLID-STATE TRANSMITTERS Therehavebeentwogeneralclassesofsolid-state devicesconsidered as.potential sourcesof microwave powerforradarapplications. Oneisthetransistor amplifier andtheotheristhe single-port microwave diodethatcano'perateaseitheranoscillator orasanegative-resistance amplifier. Thesiliconbipolartransistor has,inthepast,beenofinterestatthelowermicro­ wavefrequencies (LbandorbClow)~andthediodeshavebeenofinterestatthehighermicro­ wavefrequencies. 
 2.2.2.5 Indicating units Indicating units type 6A, 6B and 6C operated from Cole-designed receivers with a positive output and indicating units type 6 operated from the Pye receivers with a negative output. The display was a 6 inch CRT (VCR 97) with a vertical trace, withzero range at the bottom of the display. Range scales of 9, 36 or 90 miles were Figure 2.10. 
 With log-FTC thereisnoimprovement intarget-to-clutter ratioandthereisnosubclutter visibility. Thelog-FTC, orsimilarCFAR,isnecessary, however, inordertoextractthetargetinforma­ tioncontained intheradarsignalthatotherwise wouldbeundetected ifdisplayed alongwith theclutter,orwhichwouldbelostbecauseofcomputer overload inanautomatic system. Although oneofthefirstapplications considered forthelog-FTC receiverwasthedetec-. 
 NENTS v 5NIVERSITY OF .EW -EXICO  %NG %XP 3TA  !LBUQUERQUE     * - "ANHART ED   2EMOTE 3ENSING ,ABORATORY 0UBLICATION ,IST n   ,AWRENCE 5NIVERSITY  OF +ANSAS  2EMOTE 3ENSING ,AB     * - "ANHART ED    2EMOTE 3ENSING ,ABORATORY 0UBLICATION ,IST n  6OL 42 
 Sens. 2015 ,53, 6319–6335. [ CrossRef ] 14. 
 It is  possible, however, to obtain more precise criteria for specifying the maximum errors which  may be tolerated in the aperture illumination.  Systematic errors. The effect of systematic errors on the radiation pattern may be found by  properly modifying the aperture distribution to take account of the known errors. 
 ELECTRONIC COUNTER-COUNTERMEASURES  24.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 the presence of variable intensities of jamming noise. By comparison with a linear  receiver of low dynamic range, moderate jamming noise levels will normally cause  the computer to saturate so that the target signal will not be detected. The main disad - vantage is that a log characteristic causes spectral spreading of the received echoes. 
 7.5. ch15.indd   40 12/15/07   6:17:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 A first order estimate of the various contributions to signal loss can be carried out  using the standard radar range equation, although this is only applicable for far-field  conditions and thus has restrictions.  PP AG k Rert R=−. .. 
 39. R. H. 
 ,«!Bf[p 0Bfp liB=.r!J=6~;3 ~~ whereOn=anlenna beamwidth, deg .f~=pulserepetition frequency, Hz {}J=antenna scanning rate,degjs (I),"=antenna scanrate,rpm Typical parameters foraground-based searchradarmightbepulserepetition frequency 300Hz,1.5°beamwidth, andantenna scanrate5rpm(300/s).Theseparameters resultin IShitsfromapointtargetoneac;hscan.Theprocessofsumming alltheradarechopulsesfor thepurpose ofimproving detection iscalledintegration. MaRytechniques mightbeemployed foraccomplishing integration, asdiscussed inSees.to.7.Allpractical integration techniques employ somesortofstoragedevice.Perhaps themostcommon radarintegration method is thecathode-ray-tube displaycombined withtheintegrating properties oftheeyeandbrainof theradaroperator. Thediscussion inthissectionisconcerned primarily withintegration performed byelectronic devicesinwhichdetection ismadeautomatically onthebasisof3 threshold crossing. 
 7HILE 
 A phasor diagram of the system (simplified by omitting the IF sidestep) is shown in Fig. 14.11. If the output from mixer 1 is FIG. 
 /XIDE 3EMI 
 This depends  upon the application and how difficult it is for the antenna designer to achieve low sidelobes. If  the sidelobes are too high, strong echo signals can enter the receiver and appear as false  targets. A high sidelobe level makes jamming of the radar easier. 
 1966.  16. Richards. 
 APERTURE DIAMETER TO ITS EFFECTIVE BLOCKING DIAMETER  /RDINARILY  K IS SLIGHTLY LESS THAN  &OR LINEARLY POLARIZED RADAR APPLICATIONS  APERTURE  BLOCKING CAN BE SIGNIFICANTLY REDUCED BY USING A POLARIZATION 
 In one bistatic noncoherent MTI implementation, called phase priming, an oscil- lator at the receiver was phase-synchronized at the PRF rate with a small sample of close-in clutter returns.1 Phase coherence was obtained within about 10 JJLS and ex- tended over 1 ms. The process was found insensitive to the clutter signal level but quite sensitive to pulse-to-pulse phase fluctuations in the clutter signal. If coherent processing is required, phase synchronization can be estab- lished with methods similar to those used for time synchronization: directly by phase-locking the receiver to the transmit signal or indirectly by using identi- cal stable clocks in the transmitter and the receiver. 
 TI1E RADAR EQUA.I'ION 49  Number of pulses integrated, n  Figure 2.24 lntegration-improvement factor as a function of the number of pulses integrated for the five  types of target fluctuation considered.  Tlie procedure for using the radar equation when the target is described by one of the  Swerling models is as folloks:  1. Find the signal-to-noise ratio from Fig. 
 2014 , 52, 3074–3090. [ CrossRef ] 9. Moses, R.; Potter, L.; Cetin, M. 
  
 The in situ resolution  is nominally ∼40 m within a medium of permittivity ∼4. The radar dynamic range is  ∼50 dB to permit observation of subsurface profiles to a depth of several km. The  antenna is comprised of two sets of dipoles, 30 m tip-to-tip, with an effective footprint  of several tens of km. 
 In this case. the altitude of the equilateral triangle in the triangularly  arranged array is equal to the element spacing of the squarely arranged array. If instead, the  main beam is positioned not within a cone, but over a "pyramidal" region, the reduction is  less. 
 E. Fong, J. A. 
 POWERED SATELLITE TRANSMITTER ILLUMINATING THAT AREA TO CONDUCT SHORT 
 Once lock had been achieved, it was recommended that the pilot ﬂy the aircraft on the directional gyro, using the range-azimuth meter (see ﬁgure 4.13) to observe movement of the target. Steady movement of the target in azimuth would indicate the relative drift, allowing the pilot to correct the course with the appropriate aim-off to achieve a steady target bearing reading. Instructions to the Leigh Light operator on the range to the target were given by the radar operator, as the pilot was fully occupied. 
 If the trajectory  of the target is known from the measurement of the target track, it is possible to infer the  aspect of the radar projection. A radar should not be expected to provide the same target  details as are seen visually. An electromagnetic sensor, whether the eye or a radar, responds to  scattering from those details of the target which are comparable to the wavelength of observa-  tion Si~ice ttiere is sucli R large differerlce in wavelength between microwave radar and visual  sensors, the target details that are seen by radar can be quite different from what is seen  visually. 
 By observing the  target with a variable polarization producing independent measurements, the angle error due  to glint is averaged and the effect of the large glint errors is reduced. Experimental measure-  ments with an X-band, conical-scan, pulse doppler radar tracking an M-48 t8nk at approxi-  mately 500 m range reduced the angular tracking error by about one-half. In these tests, the  best results were obtained when the plane of polarization was switched in small increments  (5.6 to 22.5") at a rate greater than 500 steps per second, which is more than an order of  magnitude greater than the 40 Hz conical-scan rate. 
 Frost, V .; Stiles, J.A.; Shanmugan, K.S.; Holtzman, J.C. A Model for Radar Images and Its Application to Adaptive Digital Filtering of Multiplicative Noise. IEEE T rans. 
 BASED 3IGNAL 0ROCESSING 4ECHNIQUES FOR 2ADAR 3YSTEMS  #HAPTER   .ORWOOD   -! !RTECH (OUSE  )NC    PP n  $ ! 3HNIDMAN AND 3 3 4OUMODGE  h3IDELOBE BLANKING WITH INTEGRATION AND TARGET FLUCTUA 
 TO 
 This is typical of an  aircraft in ordinary cruising flight. Consider travel in the y direction, with z vertical and the altitude (fixed) z = h.  Then  v 1 R 1 1 1= = + −y x y zv x y h  where ( 1x, 1y, 1z) are unit vectors. 
 Increased echoes from birds are to be expected during  migratory periods (spring and fall) and during those times of day when bird activity is large  (sunrise and sunset).  Birds typically fly at speeds of from 15 to 40 knots,'* and some can fly 50 knots or greater.  These speeds are usually too high to be completely rejected by most microwave MTI radars. 
 Ferrite Phase Shifters.  Most ferrite phase shifters are nonreciprocal,91–93  and their early versions used discrete lengths of ferrite (as shown in Figure 13.35)  to implement each of the bits (180 °, 90°, 45°, etc.). In this configuration, a cur - rent pulse is passed through each bit, and the ferrite toroid is saturated. 
 Increasing the output power of a T/R module  only increases the transmit power component of the PAG product. However, adding  an additional T/R module to the array increases each of the components of the PAG:  the transmit power, the receive aperture, and the transmit gain. Therefore, radars with  a BMD function typically have a large number of elements, which results in a large  aperture. 
 NOISE RATIO   D" &)'52%    2EFERENCE CURVE OF OPTIMUM AVERAGE 3#2 IMPROVEMENT FOR    A GAUSSIAN 
  TRACKING RADAR WITH A  BEAMWIDTH AT # BAND  '(Z  WAS USED TO SIMULTANEOUSLY TRACK WITH ITS NARROW BEAM  WHICH REMAINED ABOVE THE SEA SURFACE WITHOUT SIGNIFICANT MULTIPATH ERROR  TO PROVIDE A TRUE TARGET ALTITUDE REFERENCE FOR THE DATA IN &IGURE  4HERE IS A MEASUREMENT BIAS ERROR OBSERVED IN &IGURE   OF ABOUT  4HE TRACKING DATA FROM A RADAR TRACKING A TARGET WITH A BEACON IS PLOTTED IN  &IGURE   SHOWING A TYPICAL MULTIPATH ERROR ILLUSTRATING THE PHENOMENON FROM THE REGION WHERE THE IMAGE ENTERS THE SIDELOBES TO THE REGION WHERE IT ENTERS THE MAIN BEAM 4HERE ARE THREE METHODS USED FOR PREDICTING MULTIPATH ERRORS  DEPENDING UPON WHERE THE REFLECTED TARGET IMAGE ENTERS THE ANTENNA PATTERN !T THE FAR RANGE   &)'52%     -EASURED ELEVATION 
 ITY OF THE TARGET SUPPORT STRUCTURE 4HEREFORE  IT IS THE ANTENNA HEIGHT  HA THAT IS MOST  READILY CONTROLLED AND ADJUSTED TO OPTIMIZE THE LOCATION OF THE FIRST LOBE IN THE VERTI 
 [ CrossRef ] 11. Ferro-Famil, L.; Reigber, A.; Pottier, E.; Boerner, W.M. Scene characterization using subaperture polarimetric SAR data. 
 0 1 2 3 L/RMd. ch23.indd   7 12/20/07   2:21:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 6.12). The system islargely mounted inand operated from trucks, and itcan allbetaken down, loaded ontrucks, unloaded atanew site, and erected and put back onthe airinatotal time ofless than 24hr. 7.7. 
 Reflector Antennas   ................................................. 6.1  6.1 Introducti on  .............................................................  6.1  Role of the Antenna  ........................................... 
  
 TION  THE ACTUAL DOUBLE CANCELLATION CAN BE PERFORMED BY ANY CONVENTIONAL -4) PROCESSING TECHNIQUES 0OWER IN THE !NTENNA 3IDELOBES  !IRBORNE SYSTEMS ARE LIMITED IN THEIR ABILITY  TO REJECT CLUTTER DUE TO THE POWER RETURNED BY THE ANTENNA SIDELOBES 4HE FULL  n  AZIMUTHAL PATTERN SEES VELOCITIES FROM  
 Rlultiple elevation (stacked) bearns. The use of contiguous beams stacked in elevation has beer1  employed for 3D radar. It is sometimes called a stacked-beam radar. 
 Burns, and E. M. Turner: High-Power Constant-Index Lens  Antennas, IEEE Trotrs.. 
 The comparison of TFTPCF curves between the stripmap mode and sliding spotlight mode with different CkLis shown in Figure 6. The red curves in Figure 6represent the TFTPCF value of stripmap mode ( kω=0 rad/s) and the blue curves represent the modiﬁed TFTPCF of sliding spotlight mode. It is obvious that the sliding spotlight mode is more susceptible to the 188. 
 NOISE RATIO SUPERIMPOSED%&$%" %%"      #!$('%' # #!$(' (''%'#"# &%' #    " "!    ' 
 They are often used in pulsed radars. The autocorrelation func- tions for these two cases differ with respect to the sidelobe structure. Figure 10.10 gives the autocorrelation functions for the periodic and aperiodic cases for a typical 15-element maximal-length code obtained from a four-stage shift- register generator. 
 January. 1965.  1 IH Run·. 
 Rangeerrorisproportional tothepulsewidthr, whiledoppler errorisproportional toI/r.Shortening thepulsewidthimproves therange accuracy, butattheexpenseofthedoppler-velocity accuracy. Although theshapeoftheellipse canbeasthinorasbroadasonelikesineitheraxis,theopposite willbetruefortheotheraxis. Theregioninthevicinityoftheorigincannotbemadeassmallaswewishalongbothaxes simultaneously without shifting someofthecompletely shadedregionelsewhere inthe diagram. 
 Figure 8. Cont . 167. 
 Figure 12.12 illustrates some of the sources of noise which generally  must be considered when computing the system effective noise temperature. The antenna sees  the cosmic noise at a temperature T, with an intervening absorbing atmosphere at a tempera-  ture T,, and a loss L,, . The atmosphere may be characterized for present purposes by a single  temperature and a single loss, but it can be subdivided, if desired, into an ionospheric compo-  nent, an oxygen component, and a water-vapor component. 
 DOPPLER CLUTTER  ARE THE TECHNIQUES OF ADAPTIVE PROCESSING  /RIGINALLY  THESE TECHNIQUES WERE DEVELOPED FOR AIRBORNE MICROWAVE RADARS  BUT THEY HAVE BEEN SHOWN TO HAVE WIDE APPLICABILITY IN (& RADAR n 4HE PRIMARY DOMAIN  WHERE MAJOR PERFORMANCE GAINS ARE REALIZED IS SPATIAL ANALYSIS  THAT IS  BEAMFORMING )N THIS CONTEXT  A hSNAPSHOTv OF THE OUTPUTS FROM THE ALL THE RECEIVERS ACROSS THE ARRAY IS TAKEN AND USED TO COMPUTE A SET OF COMPLEX 
 3IGMA  #ONVERTERS  $ELTA 
 the amplitude  and width of the driving pulse would be selected so as to rise up to point l on the hysteresis  curve. When the current pulse decays to zero, the magnetization falls back to the remanent  value 8,( I) along the indicated curve. The difference in phase between -Br( I) and the value  U,( I) determines the phase increment. 
 2012 ,41, 864–869. 247. Sensors 2019 ,19, 3073 26. 
 QUENCY  HOWEVER  IS NOT STRAIGHTFORWARD  AND IS USUALLY OBTAINED THROUGH NUMERICAL EVALUATION   1UADRIPHASE #ODES  1UADRIPHASE CODES ARE AN EXAMPLE OF A PHASE 
 AP-24, pp. 896-899, November, 1976.  55. 
 Atypical filling would behydrogen atapressure of10mm ofmercury, and water vapor likewise atlo-mm pressure. The hydrogen gives protection ifthewater vapor is frozen out, but deionization will then beslow. Argon isused insome tubes instead ofhydrogen. 
 Millett, R. E.: A Matched-Filter Pulse-Compression System Using a Nonlinear FM Waveform, IEEE  Trans., vol. AES-6, pp. 
 The energy-storage element is a capacitor. To prevent droop in the piilse sltape due to  the exponential nature of a capacitor discharge, only a small fract~on of the stored energy 1s  extracted for the pulse delivered to the tube. In high-power transmitters w~th long pulses the  capacitor must be very large. 
 8.2 and 8.4. For a planar array the problem is more complicated. The problem  in combining the outputs of N ports into one port, or vice versa, is to do so with minimum loss. 
 10.25. The condition foroscillation inthe desired mode occurs when themagnetron starts tooscillate and todraw current inthetime interval taken forthepulse voltage topass from Vs. L%C.10.6] MAGNETRON CHARACTERISTICS 355 toVc. 
 RATE INSTRUMENTS IN THE !,/3 PAYLOAD 4HE STANDARD POLICY  FOR THE EARLY YEARS OF  0!,3!2S ON 
 By repeating a chirp signal with an offset frequency, the repeater can appear at the  output of the pulse-compression filter ahead of the target skin-echo, thus making it harder to  separate the true signal from the repeater signal. The frequency offset can compensate for the  finite time-delay required for a repeater to respond. With a long coded-pulse signal, the  repeater can also put energy into the radar ahead of the compressed pulse, or coincident with  it, if sufficient power is used to overcome the mismatch of the repeater signal to the pulse­ compression filter. 
 On transmission it must protect the receiver from burnout or damage, and on  reception it must channel the echo signal to the receiver. Duplexers, especially for high-power  applications, sometimes employ a form of gas-discharge device. Solid-state devices are also  utilized. 
 RAY RADIATIONS AS SOME VACUUM TUBES DO  HAVE hGRACEFUL DEGRADATION v AND THAT MAINTAINABILITY IS ITS KEY ASSET /N THE OTHER HAND  PROPONENTS OF VACUUM TUBES MIGHT SAY THAT RADARS USING SOLID 
 [ CrossRef ] 6. Cafforio, C.; Prati, C.; Rocca, F. SAR data focusing using seismic migration techniques. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.816x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 unsatisfactory because the wind field rarely is homogeneous over a large geographical  area and because the wind velocity usually is a function of altitude due to wind shear  (important for rain clutter and chaff). 
 TO 
 This means that there often is a practical, economical limit to the amount of power that should be employed to increase the range of a radar. Transmitters not only must be able to generate high power with stable wave- forms, but they must often operate over a wide bandwidth, with high efficiency and with long, trouble-free life. Duplexer. 
 TO 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Radar Transmitter. 10.4  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 slow-wave tubes. 
 SUPPORT STRUCTURE AND THE REFLECTOR STIFFENING STRUCTURE MUST MAINTAIN THE FEED LOCATION AND SURFACE DIMENSIONS WHILE THE ANTENNA IS BEING ROTATED 4HIS DIMENSIONAL STABILITY MUST BE MAINTAINED THROUGH WIND LOADING  TEMPERATURE VARIATIONS  OR OTHER ENVIRONMENTAL FACTORS TO ENSURE THAT PATTERN PERFORMANCE IS MAINTAINED           
 SHAPED TRANSMIT BEAM THAT CAN BE FILLED BY PERHAPS  TO  NARROW RECEIVE BEAMS IS A POPULAR CHOICE )N THE LIMITING CASE  THE TRANSMIT ARRAY MAY FLOODLIGHT THE ENTIRE SECTOR OF COVERAGE  WHICH IS FILLED WITH RECEIVE BEAMS THAT STARE CONTINUOUSLY 4HE NONUNIFORMITY OF CLUTTER SOURCES CAN CAUSE SERIOUS PROBLEMS WITH ANY DESIGN THAT DOES NOT HAVE CONTROL OVER THE ARRAY PATTERN &URTHER  (& ANTENNAS SELDOM ACHIEVE HIGH FRONT 
 M  REFLECTOR THAT SERVED BOTH ALTIMETER BANDS AND ALSO THE RADIOMETER 3ELECTED PARAM 
 0  
 STYLE MESH REFLECTOR  KG  DRIVEN BY ONE OF TEN FEED HORNS SLIGHTLY OFFSET FROM THE FOCAL  POINT 4HIS UNITY 
 When theradar istracking atarget, thespot oflight from therange car- riage shows uponthe map just atthe position over which the airplane isflying atthat moment. The controller can thus issue hkinstructions with full and constant knowledge oftheexact position oftheaircraft under hiscontrol. This is tobecontrasted with thesituation that obtains inground control from a scanning radar; inthat case the controller has only one “look” athis target per scan—that is,perhaps once in15sec. 
 characteristics of the module. More than 180,000 transistors have been built into more than 25,000 modules. AN/SPS40. 
 P. Ruina, and C. W. 
 no. 3, pp. 157-159, September, 1967. 
   LIKE THE & 
 1059–1064, July 2002. 71. D. 
 RANGE CURVE IN &IGURE  SHIFTS TO THE LEFT )N A PULSE DOPPLER RADAR USING DIGITAL SIGNAL PROCESSING  THE !$ CONVERTERS ARE  USUALLY SELECTED TO HAVE A DYNAMIC RANGE THAT MEETS OR EXCEEDS THE USABLE DYNAMIC RANGE SET BY THE MAXIMUM CLUTTER 
 SCALE CIRCULATION PATTERNS  4/0%8 MOST FAMOUS CONTRIBUTION  IS EARLY OBSERVATION AND NEAR 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 and for large signals ( Ai >> s), it reduces to the linear detector  A x Ti i in =∑ > 1  (7.4) For constant signal amplitude (i.e., Ai = A), these detectors were first studied by  Marcum1 and were studied in succeeding years by numerous other people. 
 We suspect that nose-on incidence is at the center  of the pattern and that the charted RCS data are in decibels above a square meter at  the test frequency. Figure 14.13 charts the RCS of a ship measured at 2.8 and 9.225 GHz at horizontal  polarization. The data were collected by a shore-based radar instrumentation complex  as the ship steamed in a large circle on Chesapeake Bay. 
 89. F. J. 
 [ ] log Sensitivity LossGated PhaseN dB= +10 110o oisePowe r Density Thermal NoisePowe r Densi ity   (4.8) Table 4.5 contains a calculation of the phase noise floor requirements for an  180 kHz PRF waveform. Clutter levels that require a 12-bit (sign plus 11 amplitude  bits) A/D converter are assumed, as shown in Figure 4.16. The transmit pulse duration  is 1.75 µs, resulting in a transmit pulse bandwidth of approximately 0.5 MHz since  no pulse compression is used. 
 that is enhanced with a slow AGC. Under practical tracking conditions it seems that a  wide-bandwidth (short-time constant) AGC should be used to minimize the overall tracking  noise. However, the servo bandwidth should be kept to a minimum consistent with tactical  requirements in order to minimize the noise. 
 CHAPTER 21 SYNTHETIC APERTURE RADAR L J. Cutrona Sarcutron, Inc. 21.1 BASIC PRINCIPLES AND EARL Y HISTORY For airborne ground-mapping radar there has been continuous pressure and de- sire to achieve finer resolution. 
 Elachi, E. Im, L. E. 
 DIMENSIONAL ADAPTIVITY SHALL BE TRADED 
 32, pp. 402-428, September, 1971.  5. 
  D"   THE TOTAL PHASE 
 Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 23.8  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 receiver (and transmitter) ranges on the opposite oval are readily calculated through  mirror-image symmetry. Also note that the area of every bistatic oval is always less  than the monostatic circle. 
 H. Erhardt, “MPRF processing functions-issue 2,” Hughes Aircraft IDC, October, 18, 1977,  unclassified report. 61. 
 OLD COMPARED WITH THE IDEAL THRESHOLD 4HE FLUCTUATION IN THE ESTIMATE NECESSITATES  THAT THE MEAN THRESHOLD BE SET HIGHER THAN THE IDEAL  HENCE A LOSS )T IS ONLY APPLICABLE TO TARGETS 'UARD "LANKING ,OSS  4HIS TARGET 
 Asanexample, the Mcdel 3airborne pulser (used inthe AN/APS-15), rated at144 kwpulse power output with pulse lengths of0.5, 1,and 2psec, weighs 55lband occupies aspace 15by15by16in.; with thetechniques now available little improvement could beexpected, were this pulser redesigned. Onthe other hand, a line-type pulser with hydrogen-thyratron switch, designed for600 kw pulse output, forpulse widths of0.5and 2.5psec, weighs only 98lband has avolume ofabout 17by17by24in. Table 10.3 summarizes theadvantages and disadvantages ofthetwo types ofpulsers. 
 D.c.:RadarDetection inLog-Normal Clult~r,IEEE1975Illternat;ollal RadarCOllferellce. 1\r1ingtoll. Va..Apr.21n.1975.pp.262267. 
 N. Leith, C. J. 
 In contrast, the area below Zhongxinhe Road was generally urban districts, with densely distributed residential constructions including banks, o ﬃce buildings, and other urban infrastructure. Correspondingly, the mucky content in the soil along this stretch was relatively low. Figure 8c shows the linear velocities in Equation (8), with an overall distribution of −50 to 20 mm/y. 
 P. Iannone, “Radiation properties of a parabolic torus reflector,” IEEE Trans.  Antennas Propag ., vol. 
  
 The receiver is located at the right oval focus (0,1,2,3). Other terms and symbols are  defined in the key shown with Figure 23.2. Table 23.1 lists expressions for calculating oval area and maximum/minimum  receiver detection ranges for these four cases, again referenced to the benchmark range,  RM.* For Figure 23.2 d when L > 3RM, the ovals can conveniently be approximated as  circles with radius RR(av)  ~ RM2/L and corresponding area p RM4/L2. 
 685–696, 2000. 139. M. 
 Gain control ability: Pulse shaping can be accomplished by using low power gate bias modulation. 3. Ease of impedance matching: This is particularly true for the static induc- tion transistor (SIT), which can operate from dc supply voltages as high as 100 V and hence can provide higher impedance levels than other device types for a given power output level. 
 Results for the San Francisco dataset. Methods FP FN OE PCC (%) KC (%) NR-ELM 328 440 768 0.9883 0.9107 GaborTLC 1376 60 1436 0.9781 0.8539 PCAKM 1855 73 1928 0.9706 0.8115 Proposed method 836 685 1521 0.9768 0.8277 It should be noted that the proposed framework provided better results compared to the other methods when the datasets contain registration and perspective errors with speckle noise. Otherwise, the performance of the proposed method is comparable to PCAKM as a change detection algorithm since the optical ﬂow processing stage cannot provide matching regions in the images. 
 Unlike the antennas of amplitude­ comparison trackers, those used in phase-comparison systems are not offset from the axis. The  individual boresight axes of the antennas are parallel, causing the (far-field) radiation to  illuminate the same volume in space. The amplitudes of the target echo signals are essentially  the same from each antenna hcam, but the phases are different. 
 16.12 in terms of these coordinates as  W fd dfPG d Rr d dt=    η λ πσ ξ2 32 0 44( ) strip p∫ (16.13) Note that Pt, the transmitted power, is non - zero in the integral only for the time it illu - minates the ground. In pulse radars, only that  part of the ground area providing signals back  to the radar at a particular time can be con - sidered to have finite Pt, and so the range of  frequencies that can be present is limited by  the pulse, as well as by the antennas and the  maximum velocity. Another example is shown in Figure 16.9. 
 Coherent processing time, T: For ranges beyond the skip distance, HF radar returns  almost invariably contain Earth backscatter at the same ranges as targets. Doppler  processing is used to separate targets from Earth backscatter; hence, coherent sam - ples are acquired over an interval T, which may exceed 100 s, though it is usually  in the range of 1–20 s. Wavelength ( l): The wavelength or operating frequency must be selected so that  the transmitted energy is reflected by the ionosphere to illuminate the desired area  of the Earth. 
 By  definition, SLC files are in amplitude and phase, often represented as an array of in- phase (I) and quadrature (Q) signed number pairs, at each pixel. SLC data are required  for SAR interferometry, polarimetry, and coherent change detection. Pushing Ambiguity Limits. 
 frequency  characteristic is followed by a hard limiter and by a second dispersive delay line with a  characteristic inverse to the first. (H the limiter were omitted, the circuit would operate simply  as a linear nondispersive time delay.) It has been claimed that there was no discernible loss in  detectability with this CF AR, but that the detectability loss for log-FTC is about 3 dB.  A variation of this technique has been applied to chirp pulse-compression radar to  achieve CF AR in conjunction with pulse compression. 
 . Radar System Engineering  Chapter 3 – The Radar Equation  18     The derivation of the Radar equation for bistatic Radar is as with monostatic Radar. Simply the  grouping of terms is different. 
 DELAY CANCELER WEIGHTS SHOULD BE  ! #4 4 "#. . 
 Goto, N., and D. K. Cheng: Phase Shifter Thinning and Sidelobe Reduction for Large Phased  Arrays, IEEE Trans., vol. 
 There is a limit as to how long the gate  width can be increased before phase differential and signal attenuation along the longer  dimension of the gate width begin to have a deleterious impact on amplifier perfor - mance. In practice, the maximum gate width can be found to approach approximately  400 µm, 150 µm, or 60 µm for S band, X band, or Ka band frequencies, respectively. With a limitation on maximum gate width, additional current and hence power  capability can only be achieved by combining multiple gate electrodes in parallel. 
 Thus a medium resolution radar might have a  20 dB advantage over low-resolution radars in the detection of targets in land clutter. The . RADAR CLUTTER 495  10  o- Downtown phoenix  Highest median vofue  in SS :1QOO  .:9 -10 0  b  ci Phoernx 55 >25,000  f!  0 N J residenlial -20 c :;, NJ rural ... 
  
   '2/5.$ %#(/  £È°Ó£ FROM COMPANIES THAT SUPPLY THAT MARKET &OR  DISCUSSION OF THE RELATIVE MERITS OF DIFFERENT PASSIVE CALIBRATION TARGETS  SEE 5LABY ET AL  4HE IDEAL RECEIVER WOULD RESPOND LINEARLY  TO ITS INPUT  SO THAT A SINGLE CALIBRATION AT ONE INPUT LEVEL WOULD SUFFICE FOR ALL LEVELS 4HE USUAL RECEIVER  HOWEVER  HAS SOME NON 
  
 Krishnan, S.: Diode Phase Detectors, Electronic and Radio Engr., vol. 36, pp. 45-50, February, 1959. 
 This depends  upon the application and how difficult it is for the antenna designer to achieve low sidelobes. If  the sidelobes are too high, strong echo signals can enter the receiver and appear as false  targets. A high sidelobe level makes jamming of the radar easier. 
 There was an appreciation of the possible effects of multipath scattering, leading to interference between the direct signal from the radar at the target and the signal reﬂected off the sea surface. Simple theory predicts that when operating at low altitude the power received from a point target at a ﬁxed height above a smooth reﬂecting surface should be proportional h 4/R8where his the aircraft height and Ris the slant range between the radar and the target. This suggested that the range Rat which a given power level would be received should vary in proportion to hand this effect was expected to be observed in early trials. 
 For asystem that works atleast partially over land itisadvisable, however, tominimize the radiation striking thesurface bybeam-shaping, inorder toreduce thewaste inenergy. Antenna height required forsatisfactory beam-shaping isnot excessive. Inthe region of25cm, assessment ofthe influence ofthese effects onthegeneral performance oftheequipment becomes difficult, but fora high-performance set ofgeneral application the above considerations indicate that the best coverage obtainable asafunction ofelevation angle continues toimprove with decreasing wavelength down towave- lengths even below 10cm. 
 and P. W. Hannon: A Cylindrical Phased-Array Antenna for ATC  Interrogation. 
 TRONICALLY SCAN THE ERRORS INDUCED BY PHASE SHIFTERS  ACTIVE COMPONENTS  AND FEED ELEMENTS MUST BE INCLUDED IN THIS BUDGET !RRAYS HAVE BEEN REALIZED IN PRACTICE THAT HAVE PEAK SIDELOBES IN THE VICINITY OF THE  
 6.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 Radar Receivers* Michael E. 
 This  describes the ability of an MTI radar to detect moving targets which occur in the relatively  clear resolution cells between patches of strong clutter. Clutter echo power is not uniform, so  if a radar has sufficient resolution it can see targets in the clear areas between clutter patches.  The higher the radar resolution, the better the interclutter visibility. 
 The waveguide horn is probably the  most popular method of feeding a paraboloid for radar application.  Optimum feed illumination angle. If the radiation pattern of the feed is known, the illumina-  tion of the aperture can be determined and the resulting secondary beam pattcrn can be found  by evaluating a Fourier integral or performing a numerical calculation. 
 TEM  THERE IS ONLY ONE RECEIVER AND !$#  AND THE DYNAMIC RANGE PERFORMANCE IS LIM 
 Several nonarray techniques using reflectors or lenses have  been considered for the generation of multiple beams. The Luneburg lens and the torus  reflector with multiple feeds as described in Chap. 7 are examples. 
 DETECTOR SLOPE 4HE VALUE OF  KM IS DETERMINED BY THE  STEEPNESS OF THE ANTENNA DIFFERENCE PATTERNS  AND A VARIETY OF VALUES CAN BE OBTAINED   DEPENDING ON THE TYPE OF FEED USED 4HE VALUES VARY FROM  FOR THE ORIGINAL FOUR 
 MENTS  AND TECHNIQUES v 0ROC )%%%  VOL   PP n  &EBRUARY   (EWLETT 0ACKARD 0RODUCT .OTE " 
 !" OPERATED AMPLIFIER IS BIASED JUST ABOVE  CONDUCTION USING A TRICKLE QUIESCENT CURRENT AND IS ALSO COMMONLY USED AS A PUSH 
 IRE, vol. 48, pp. 171 5.- 1727, October, 1960. 
 OF 
 Thetechnique wassimilartothefirstUnitedStatesradar-detection experiments. Thetransmitter andreceiver wereseparated byabout5.5miles.Whentheaircraftreceded fromthereceiver, itwaspossible todetectthebeatstoaboutan8-milerange. ByJune,1935,theBritishhaddemonstrated thepulsetechnique tomeasure rangeofan aircraft target. 
 WEIGHTED CANCELER IS ASSUMED WITH THE RADAR OPERAT 
 E. Wood: System Considerations for the Design of Radar Braking Sensors,  IEEE Trans., vol. VT-26. 
 11. Smith. R. 
 I RE,  vol. 4J. pp. 
 First, the quantities given fornumbers ofsidebands, noise band, etc., areonly qualitatively correct; really precise definitions would require so many qualifications astorender thequantities either useless orconfusing. Second, neither the table nor this chapter pretends todescribe allc-w systems; atleast adozen more areknown and nodoubt still more could be invented. Itisbelieved, however, that representatives ofallimportant types have been included. 
 (ILL #OMPANIES     3EC   ! 3 'ILMOUR  *R   -ICROWAVE 4UBES  .ORWOOD  -! !RTECH (OUSE    3EC   , , #LAMPITT  h3 
 In some cases the actual range might be only half that predicted.'  Part of this discrepancy is due to the failure of Eq. (2.1) to explicitly include the various losses  that can occur throughout the system or the loss in performance usually experienced when  electronic equipment is operated in the field rather than under laboratory-type conditions.  Another i,nportant factor that must be considered in the radaf equation is the statistical or  unpredictable nature of several of the parameters. 
 SIGHT ,/3  INTERSECTS THE FLAT GROUND AT GRAZING ANGLE  X &IGURE    7E CONSIDER TWO POSSIBILITIES   ONE ANTENNA TRANSMITS AND EACH RECEIVES N       AND    ANTENNA ! TRANSMITS AND THEN RECEIVES THEN ANTENNA  " TRANSMITS AND THEN RECEIVES N      .   39.4(%4)# !0%2452% 2!$!2   £Ç°Î£ &OR A hSINGLE 
 SECTION OF THE 'UYANA 2AIN &OREST POSSIBLE USE  AS A REFERENCE TARGET FOR SPACEBORNE RADARS v 2EMOTE 3ENSING OF %NVIR  VOL   PP n  .   '2/5.$ %#(/  £È°xÇ  ! 2 %DISON  2 + -OORE  AND " $ 7ARNER  h2ADAR RETURN MEASURED AT NEAR 
 H. Richter: Integrated Refractive Effects Prediction System (IREPS). URSI  Commission F Open Symposium, Propagation in Non-Ionized Media, La Baule, France, Apr. 
 (4.16). Filter sidelobes not  Frequency shown.  122INTRODUCTION TORADAR SYSTEMS wherei=1,2,...,Nrepresents theithtap,andkisanindexfrom0toN-1.Eachvalueofk corresponds toadifferent setofNweights, andtoadifferent doppler-filter response. 
 G. C.: " Frequency Modulated Radar." McGraw-Hill Book Company, New York. 1949. 
 F. A. Sikta, W. 
 However, when concerned with deep neural networks, such as Resnet-50, the repeated images cannot give more contributions for training. Thus the performance cannot have more improvement.     (a) (b) (c)  Figure 7. 
 D. O'Brien, and W. K. 
   CIRCULAR LOW 
 Hapke, “Coherent backscatter and the radar characteristics of outer planet satellites,” Icarus ,  vol. 88, pp. 407–417, December 1990. 
 PHYSICAL INVESTIGATIONS  AS WELL AS SKYWAVE RADAR -ODELS OF THE )ONOSPHERIC -EDIUM  -ODELS OF THE IONOSPHERE FALL INTO TWO   CATEGORIES u #LIMATOLOGICAL MODELS BASED ON SOUNDER  ROCKET  AND SATELLITE MEASUREMENTS "EING  DERIVED FROM STATISTICS  THEY PROVIDE NO EXPLICIT INFORMATION ON REAL 
 The magnetron is an oscillator that has less flexibility and is usually noisier than  a linear-beam amplifier. Each time a pulse is transmitted, its phase is different from  the phase of previous pulses. That is, its phase is random from pulse to pulse. 
 It is further assumed in the present example that the reflection coefficient r = - 1. The  reflected wave suffers no change is amplitude, but its phase is shifted 180". A reflection  coefficient of - 1 applies at microwave frequencies to a smooth surface with good reflecting  properties if the radiation is horizontally polarized and the angle of incidence is small. 
 Levanon, Radar Principles , New York: Wiley-Interscience, 1988. 18. R. 
 ERROR SENSITIVITY  TO UNITS OF ANGLE  AND MOVES TO THE NEXT TARGET 4HE SYSTEM DETERMINES WHERE THE TARGET WAS AND  FROM CALCULATIONS OF TARGET VELOCITY AND ACCELERATION  PRE 
 BEAM AZIMUTH       DEPRESSION ANGLE    . {°£È  2!$!2 (!.$"//+  )F THE MAIN BEAM WERE SCANNED  IN AZIMUTH WITH THE SAME RADAR PLATFORM  KINEMATICS  THE MAIN 
 STATE POWER SOURCES  AND IS CAPABLE OF OPERATING AT HIGH AMBIENT TEMPERATURES 4HE GAIN OF AN -0- MIGHT BE NOMINALLY  D" AND IS DIVIDED BETWEEN THE SOLID 
 THE 
 Forexample, witharelativevelocityof 5mls(10kt)thedopplerfrequency shiftatI-Jimwavelength is10MHz.Arapidlytuninglaser localoscihator oralargehankofIFfiltersarenecessary tocompensate forthefargedoppler frequency shift. Whenthetargetisinthefarfieldofthelaserantenna, andiftheantenna beamislarger thanthetarget.theusualformofthesimpleradarequation ofSec.1.2applies.However. the beamwidth ratherthantheantenna gainisusuallymeasured atlaserfrequencies sothat <i,=rr2I(}~mayhesuostituted intotheradarequation. 
  XR   =  4HE EQUIVALENT 
 Another is that ordinary methods of solution (matrix inver - sion and gaussian elimination, for example) may be employed to effect a solution. This  method is limited by computer memory and execution time, however, to objects a few  dozen wavelengths in size at best. Alternatives to these exact solutions are several approximate methods that may be  applied with reasonable accuracy to electrically large target features. 
 LOOP TECHNIQUES  IN WHICH THE OUTPUT RESIDUE CONNECTION A IN & IGURE   IS FED BACK INTO  THE ADAPTIVE SYSTEM AND   DIRECT 
 [ CrossRef ] 15. Li, X.; Liu, G.; Ni, J. Autofocusing of ISAR images based on entropy minimization. 
 Of course, when  sampled they are folded back into the Nyquist passband. These aliases are azimuth  ambiguities, which are suppressed—hence not visible—in a well-designed system  supported by a well-tuned processor. When they do appear, azimuth ambiguities are  relatively easy to identify (Figure 18.5) because they are weaker (ghost) duplicates of  image features that were collected through the main beam and, therefore, at earlier or  later positions along the image strip. 
 WhentheSARislocatedonasatellite, theeffectofearth rotation mustbeproperly compensated sinceitresultsintheearth'ssurfaceappearing asa movingtarget.IO,9! Thedifference insignalcharacteristics fromamovingtargetascompared tothatfroma stationary targetcanbeusedasabasisforcombining AMTI(airborne movingtargetindica­ tion)withSAR.8Themoving-target doppler shiftcanbedetected whenitexceedstheclutter doppler-spectrum width.Itisalsopossible touseadualsidelooking antenna patternand detectthephasedifference between thetwomutually coherent observations ofatarget separated intime.Thephase-detection AMTImethod allowsslowlymoving targetstobe detected whentheaircraftvelocity islarge. Ground relief,suchasduetohillsormountains, standsoutonSARimagery becauseof theshadows theyform,especially whenviewedatlowgrazingangles.Shadows helpemphasize topographic andgeologic features thatpermitatrainedinterpreter tolearnmuchaboutthe natureoftheterrain.(Optical photographs aregenerally takenfromlargegrazinganglesand donotshowthesameshadowing effectsproduced byradar.)Stereoscopic techniques canalso beappliedtoSARtoprovideathree-dimensional imageoftheterrain.Thisisaccomplished byviewing thesameterrainfromdifferent aspects,suchasbyflyingtwoseparate flightpaths toproduce imagesfromtwodifferent elevation angles.12Itisalsopossible togenerate apaIrof stereoimagesonasinglepassusingtwoverticalfanbeamsatdifferent azimuth angles,orone fanbeamandaconicalbeam.13Thestereoprocessing ofSARimageshasbeensuccessfully usedformineralexploration. Atshortrangesitispossible touseconventional noncoherent sidelooking radarwitha largeantenna aperture andpulsecompression toobtainhigh-resolution terrainimaging. 
 For the upper end of the solid-state microwave spectrum, i.e., the millimeter- wave range, the single-port microwave diode can be used as a low-power oscil- lator. Unfortunately, the power output and efficiency of these devices are in gen- eral very low; in fact, the efficiency is significantly lower than that of their tube counterparts. However, CW and pulsed power output are attainable up to 300 GHz. 
 Use of a differential scattering cross section implies that the return from the ground is contributed by a large number of scattering elements whose phases are independent. This is primarily because of differences in distance that, although small fractions of total distance, are many wavelengths. Superposition of power is possible for the computation of average returns. 
   PP n  .OVEMBER . 
 SCAN  AND SEQUENTIAL LOBING TRACKING 
 For purposes of the present discussion,  tiowever, the exact origin of tlie extra noise components is not important except to know that  it exists. No matter whether the noise is generated by a thermal mechanism or by some other  mechanism. tile total tloise at tlie output of the receiver may be considered to be equal to the  thermal-noise power obtained from an " ideal " receiver multiplied by a factor called the iroise  fig~rre. 
 In order to further verify the proposed algorithm, the coherent pulse number is changed from 32 to 64, and the selected pulse is the central part of the echoed signal. For example, the 49th to the 80th pulse in each azimuth angle is selected to form the 32 pulses data set, and the 33rd pulse to the 96th pulse in each azimuth angle is selected to form the 64 pulses data set. Di ﬀerent algorithms with diﬀerent pulses are compared in Figure 10. 
 ELEMENT ARRAY  THE NULL IS VERY PRONOUNCED %VEN FOR THE  
 It was agreed that a 3 cm ASV systemshould be considered. In the UK this resulted in plans for ASV Mk. VII, as discussed in chapter 5. 
 Millett: A Double-Slot Radar Fence for Increased Clutter Suppression, I £EE  Trans., vol. AP-16, pp. 103-108, January. 
 LINE CIRCUIT CONFIGURATION  USING EITHER DISTRIBUTED TRANSMISSION 
 (10.38) can be written ,  which is the characteristic of a square-law detector.  Hence it may be concluded that for small signal-to-noise. ratios the square-law detector  may be a suitable approximation to the optimum detector, while for large signal-to-noise  ratios the linear detector is more appropriate. 
 BASED MEASUREMENTS HAVE ALSO BEEN REPORTED  "ISTATIC MEASUREMENTS CALL FOR COMPLICATIONS WHEN MADE OUTSIDE THE LABORATORY  BECAUSE AN ABSOLUTE REFERENCE FOR BOTH TRANSMITTER POWER AND RECEIVER SENSITIVITY MUST BE USED )N THE LABORATORY  HOWEVER  IT IS POSSIBLE TO USE TECHNIQUES SIMILAR TO THOSE FOR MONOSTATIC MEASUREMENTS £È°ÈÊ  
 MENTS  ILLUSTRATED HERE BY &IGURE   WHICH SHOWS AN EXAMPLE OF THE FREQUENCY SPECTRUM DERIVED FROM WAVE BUOY MEASUREMENTS ! COMMON FEATURE OF SUCH WAVE SPECTRA IS THAT WAVES OF A GIVEN WAVELENGTH TEND TO REACH A LIMITING SPECTRAL DENSITY  BEYOND WHICH THE PROCESSES OF DISSIPATION AND NONLINEAR TRANSFER OF ENERGY TO OTHER WAVENUMBERS PREVENTS FURTHER GROWTH 4HIS CONDITIONKNOWN AS SATURATION  OR BEING FULLY DEVELOPEDIS REACHED AT QUITE MODEST WIND SPEEDS FOR THOSE WAVES RESPONSIBLE FOR FIRST 
 Farnell: A Homogeneous Dielectric Sphere as a Microwave Lens, Call. J.  Phys.. 
 DOWN OR UP 
 24. Trirna. D. 
 The sub-clutter vis - ibility (SCV), widely used in HF radar as a measure of sensitivity and defined as  R/N, is 76 dB in this example. (In microwave radar, the term sub-clutter  visibility  is sensibly defined as the ratio by which the target echo power may be weaker than  the clutter power and still be detected. In the HF radar literature, historically the  detection threshold component has not been included, so SCV is essentially the  clutter-to-noise ratio.) For a representative effective clutter RCS of 65 dBsm per resolution cell, the target  RCS can be estimated as  RCS = 65 − R(dB) + T(dB) = 65 − 76 + 34 = 23 dBsm  and supposing that the SNR required for registering a detection is 15 dB, the minimum  detectable RCS (MDRCS) in this example can be computed as  MDRCS = 65 − R + N + 15 = 65 − 76 + 15 = 4 dBsm  ch20.indd   49 12/20/07   1:16:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 J. Parsons;: The Rridar Measurement of Low Angles of Elevation. Proc. 
 (1634) divided by (10.33)] is  where I is the constant which depends on the false-alarm probability. Taking the logarithm  gives  a2 In Io(avi) t In I + n - 2 (10.36)  i= 1  This states that for optimum processing one should take the pulses, each of amplitude v,  n  (where i = I, 2, . ., n), and sum them according to the law C In lo(av,). 
 Thus for detection of a target in clutter the radar beam should be narrow and the pulse width should be short. With assumptions other than those above, the im- portant radar parameters for detection of targets in clutter might be different. If n hits are received per scan and if the clutter is correlated from pulse to pulse, no improvement in SIC is obtained as it would be if thermal noise, rather than clut- ter, were the limitation. 
 They include the theories of geometrical and physical optics, the geometrical and physical theories of diffraction, and the method of equivalent currents. These ap- proximations are discussed in Sec. 11.3. 
 FREQUENCY NOISE COMPONENTS 4HE RATE OF AMPLITUDE FLUCTUATIONS OF THE ENVELOPE OF THE ECHO PULSES IS APPROXIMATELY PROPORTIONAL TO THE RADAR FREQUENCY ! MATHEMATICAL MODEL OF LOW 
 The  riG. 14 cathode follower (Fig. 15) has one  important difference. 
 It obviously would not make sense for a radar to have a huge, costly antenna and a tiny, inexpensive transmitter, or vice versa, because doubling the tiny part would allow cutting the huge part in half, which would clearly reduce total sys- tem cost. Thus, minimizing total system cost requires a reasonable balance be- tween the costs of these two subsystems. The result, for any nontrivial radar task, is that significant transmitter power is always demanded by the system de- signers. 
 The theoretical  accuracy with which range can be measured with the two-frequency CW radar can be found  96INTRODUCTION TORADAR SYSTEMS SincethetwoRFfrequencies!l and!zareapproximately thesame(thatisJz=/1+AI.where 11/~!dthedoppler frequency shifts!d1and/dZareapproximately equaltooneanother. Therefore wemaywriteh1=hz=h. Thereceiver separates thetwocomponents oftheechosignalandheterodynes each received signalcomponent withthecorresponding transmitted waveform andextractsthetwo doppler-frequency components givenbelow: ThephasedilTerence between thesetwocomponents is 11<jJ=~n(fz-!I)Ro=4n4{Ro c c(3.20(1) (3.20/1) (3.2t) Hence (3.22) whichisthesameasthatofEq.(3.17),withI1fsubstituted inplaceofro. 
 Thereceived echosignalisassumed tobethesameasthetransmitted signalexceptforthetimedelayToandadoppler frequency shiftfd'Thus (11.47) (Thechangeofamplitude oftheechosignalisignoredhere.)Withthesedefinitions theoutput ofthematched filteris et) Output=fu(e-To)ej27tUo+fdHI-To)[u(e -T~)ej2nJo(I-Till]* de -et) =fet)u(e-To)u*(e-T~)ej27tUo"'fdHI-To) e-j2nfo(I-TR) de -et) . J(11.48) Itiscustomary tosetTo=0andfo=0,andtodefineTo-TR= -TR=TR.Theoutputof thematched filteristhen X(TR,fd)=fet)u(e)u*(e+TR)ei2xfdl de-et)(11.49) (11.54)InthisformapositiveTRindicates atargetbeyondthereference delayTo,andapositivefJ indicates anincoming target.l3Thesquared magnitude Ix(TR,fd)12iscalledtheambiguicy function anditsplotistheambiguity diagram. Theambiguity diagram hasbeenusedtoassesstheproperties ofthetransmitted waveform asregardsitstargetresolution, measurement accuracy, ambiguity, andresponse to clutter. 
 L. Spafford, “Optimum radar signal processing in clutter,” IEEE Trans. , vol. 
 I EE, vol. 95, pt. IIIA, pp. 
 Mentzer, J. R.: "Scattering and Diffraction of Radio Waves," Pergamon Press, New York. 1955. 
 Stainless steel or plastic coated galvanized steel are used when the surface  must be resistant to corrosion. Aluminum is light in weight but is more expensive than steel.  Aluminum honeycomb with aluminum skin in a sandwich construction has been employed  where highly accurate surfaces are required. 
 ING ALGORITHMS  INCLUDING BISTATIC 3!2 AUTOFOCUS AND IMAGE FORMATION AND SPACE 
 RF tubes used in amplifier chains are often more "fussy" about the match they see than oscillator tubes. Because good isolators are now gener- ally available, improved amplifier ratings are sometimes available if the tube is guaranteed to see a good match, such as 1.1:1. Furthermore, CFAs and traveling- wave tubes (TWTs) generally require that the match they see be controlled over . 
 TOR ANTENNA DESIGN 3ECTION  PROVIDES A BRIEF OVERVIEW OF CONIC SECTIONS AND CLASSES  OF REFLECTOR SYSTEMS AND ASSOCIATED OPTICS 3ECTION  DISCUSSES VARIOUS TYPES OF REFLECTOR FEEDS AND RELATED DESIGN PRINCIPLES 3ECTION  DESCRIBES REFLECTOR ANALYSIS AND SYNTHESIS METHODS AND ASSOCIATED DESIGN SOFTWARE PACKAGES &INALLY  3ECTION  BRIEFLY REVIEWS MECHANICAL DESIGN ISSUES AND CONSIDERATIONS £Ó°ÓÊ  - Ê*,  * 
 Active Stabilization. All the schemes for active stabilization on a MOPA chain depend on the use of a high-g cavity as the reference element. The cavity must be isolated from the tube so that it functions as a measuring device without introducing the pulling that results from the frequency dependence of its susceptance. 
 MISE BETWEEN THE REQUIRED MEMORY AND SEVERAL PERFORMANCE CHARACTERISTICS 4HESE ARE THE MINIMUM TARGET VELOCITY THAT WILL NOT BE SUPPRESSED BY THE MAP SO 
 BAND RADAR IN VEGETATION MAPPING v  0HOTOG %NG AND 2EM  3ENS  VOL   PP n    0 # $UBOIS AND * VAN :YL  h0OLARIZATION FILTERING OF 3!2 DATA v  $IGEST )'!233  VOL     PP n    ! ! 3WARTZ ET AL  h/PTIMAL POLARIZATION FOR ACHIEVING MAXIMUM CONTRAST IN RADAR IMAGES v   * 'EOPHYS 2ES  VOL   PP n    3 2 #LOUDE AND % 0OTTIER  h!N ENTROPY BASED CLASSIFICATION SCHEME FOR LAND APPLICATIONS OF  POLARIMETRIC 3!2 v )%%% 4RANS ON 'EOSC AND 2EMOTE 3ENSING  VOL   PP n    * VAN :YL  h5NSUPERVISED CLASSIFICATION OF SCATTERING BEHAVIOR USING RADAR POLARIMETRY DATA v  )%%% 4RANS 'EOSC 2EM 3ENS  VOL   PP n     4OUZI ET AL  h0OLARIMETRIC DISCRIMINATORS FOR 3!2 IMAGES v  )%%% 4RANS ON 'EOSC AND 2EMOTE  3ENSING  VOL   PP n    3 , $URDEN  * $ +LEIN  AND ( ! :EBKER  h0OLARIMETRIC RADAR MEASUREMENTS OF A FORESTED AREA  NEAR -T 3HASTA v )%%% 4RANS ON 'EOSC AND 2EMOTE 3ENSING  VOL   PP n     (OEKMAN ET AL  h"IOPHYSICAL FOREST TYPE CHARACTERIZATION IN THE #OLUMBIAN !MAZON BY AIRBORNE  POLARIMETRIC 3!2 v )%%% 4RANS ON 'EOSC AND 2EMOTE 3ENSING  VOL   PP n    0 &ERRAZZOLI ET AL  h4HE POTENTIAL OF MULTIFREQUENCY POL ARIMETRIC 3!2 IN ASSESSING AGRICULTURAL  AND ARBOREOUS BIOMASS v )%%% 4RANS ON 'EOSC AND 2EMOTE 3ENSING  VOL   PP n    )NOUE ET AL  h3EASON 
 E.: Eliminating Transmitted Clutter in Doppler Radar Systems, Microwaot~ J., vol. 18.  pp. 
 Sovetskoye Radio. Moscow, 1963. Translation available from NTIS, AD 645775, June 28, 1966. 
 The measurement of the  receiver output with the noise source on (N 2) and the noise source off (Ni) can be made on  alternate pulse periods.  The receiver noise-figure or sensitivity can also be measured by use of a calibrated signal  generator. With a matched resistance at the receiver input, the output power is due to receiver  noise alone. 
 This quantity is the generalized ambiguity function, given by /r 9/?i r 9T?'!fit \J*\t-—\dt (21.20)L c J L c J In terms of the generalized ambiguity function defined by Eq. (21.17), Eq. (21.19) can be rewritten as e0 = JJJ X(xy,z;x',y',z')p(x9y,z) dx dy dz (21.21) Equation (21.21) shows that the ambiguity function can be considered as a weighting function on p(x,y,z). 
 MITTERS  MORE COVERT AND LESS RISKY THAN USING A DEDICATED TRANSMITTER #ONSEQUENTLY  DEDICATED TRANSMITTERS ARE NOT USUALLY CONSIDERED FOR THESE APPLICATIONS %NTRIES IN THE COOPERATIVE AND NONCOOPERATIVE TRANSMITTER COLUMNS ARE CALLED  HITCHHIKERS WHEN THE TRANSMITTER IS A MONOSTATIC RADAR 7HEN THE TRANSMITTER IS FROM  A COMMUNICATIONS OR BROADCAST SYSTEM  IE  NOT FROM A RADAR  ENTRIES ARE CALLED A PASSIVE BISTATIC RADAR 0"2  %XAMPLES OF A HITCHHIKER OPERATING WITH A COOPERATIVE TRANSMITTER IN THE CO 
 47; that is, they are presented in terms of gR/R0, where the g factor is a function of the number of pulses integrated noncoherently and the probability of false alarm. For coherent integration N=I and g becomes g = [ - €*(/>FA)]1/4 (17-24) NUMBER OF PULSES INTEGRATED N FIG. 17.20 Swerling's g factor as a function of PPA and N (after Ref. 
 TO 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 5.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 MPRF-Typical Range-Doppler Blind Map. 
 13.21  Other Effects on Sea Clutter  ..............................  13.23  13.4 Theories of S ea Clutter  ...........................................  13.27  Theories Based on Global Boundary-Value  Problems  ......................................................... 
 Titus, “Mirror-antenna radar concept,” Microwave J .,   vol. 29, pp. 323–335, May 1986. 
 ERROR 
 On the longer range scales, the increase in echo size because of spot size is appreciable. Range Scale The pips of two targets separated by a few hundred yards may merge on the PPI when one of the longer range scales is used. The use of the shortest rangescale possible and proper adjustment of the receiver gain may enable theirdetection as separate targets. 
 K. Raney, “Stokes parameters and hybrid-polarity SAR architecture,” IEEE Transactions  Geoscience and Remote Sensing , vol. 45, pp. 
 The searchlight technique was successfully employed on the British CMH radar and on the widely deployed United States SCR-5845 as well as on the United States SCR-615 and the U.S. Navy SM radar. All these radars were S-band dish antenna radar systems. 
 21-23, 1975, IEEE Publi-  cation 75 CHO 938- 1 AES.  127. Bearse. 
 CATED TO EACH OF THE TWO CANCELERS WAS FIXED  BASED ON AN A PRIORI ASSESSMENT OF THE CLUTTER SUPPRESSION REQUIREMENT 4HE ONLY VARIATION POSSIBLE WOULD BE TO COMPLETELY BYPASS ONE OR BOTH  OF THE -4) CANCELERS IF NO LAND CLUTTER OR WEATHER OR CHAFF RETURNS ARE RECEIVED ON A GIVEN RADIAL ! MORE CAPABLE SYSTEM CAN BE IMPLEMENTED IF THE NUM 
 The linear-array system requires a solid surface forthe reflector, since the comparatively high gain ofthe linear-array feed will give anobjectionable back lobe through mesh orgridwork. The ilfodulator.-Because ofits simplicity and power-handling capacity, ana-cresonance-charging line-type modulator using arotary FIG. 156.—Modulator ofhigh-power ground radar. 
 Slant  range is the line of si ght distance between the radar and the object illuminated. While ground range  is the horizontal distance between the emitter and its target and its calculation requires knowledge  of the target's elevation. Since the waves travel to a target and back, the r ound trip time is divide d  by two in order to obtain the time the wave took to reach the target. 
 WAVE BISTATIC SCATTERING FROM GROUND AND VEGETATION TARGETS v  )%%% 4RANS 'EOSC  2EM 3ENS  VOL '% 
 02& OR -4)  WAVEFORMS THAT ARE RANGE UNAMBIGUOUS (OWEVER  FOR HIGHLY RANGE AMBIGUOUS MEDIUM 
 OF 
 W., Jr., and K. M. Siegel: "Methods of Radar Cross-Section Analysis," Academic Press. 
 The insulator, which is the storage medium, is illuminated continuously by a "flood" beam.  When illuminated by the writing beam, charge is stored on the insulator surface because of  its secondary emission characteristics. The information written on the insulator storage  surface forms a charge pattern that is made visible by the action of the flood beam. 
 NADIR CLUTTER ARISING FROM SOURCES IN THE ALONG 
  
 The effect of target suppres - sion with log video is discussed later in this section (see Table 7.2, later in the chapter). Nonparametric Detectors . Usually nonparametric detectors obtain CFAR by rank - ing the test sample with the reference cells.30,31 Ranking means that one orders the  samples from the smallest to the largest and replaces the smallest with rank 0, the next  smallest with rank 1, . 
  v %NGINEERING %XPERIMENT 3TATION  'EORGIA )NSTITUTE OF 4ECHNOLOGY  !PRIL . 
 When the angles of incidence exceed the limiting value the contours ofthe radome must be adjusted until theupper limit ofangle ofincidence isnot exceeded. 9.24. Structural Design ofRadomes.—The thickness and construc- tion oftheradome wall can bedetermined onthebasis ofstructural con- siderations within limits depending upon the allowable reflection. 
 !jetailed descriptions of the various radiators used for arrays may be found in the standard  texts on antennas and will riot be discussed here. It should be cautioned, however, that the  properties of a radiating element in an array can differ significantly from its properties wt~en in  free space. For example, the radiation resistance of an infinitely thin, half-wave dipole in free  space is 73 ohms, but in an infinite array with lialf-wavelength element spacing and a back screen  ofquarter-wave separation it is 153 ohms when the beam is broadside. 
 The next most frequently used function is the exponential: p(Q = e~^IL (12.6) This has some basis in contour-map analysis;41 the results fit both earth and lunar radar return over a wider range of angles than the gaussian41'44 (but sometimes not as well near vertical). Furthermore, it has the merit that it exhibits frequency dependence. Resulting expressions for power (scattering coefficient) variations appear in Table 12.1. 
 V, Division 14, "Radar," available from Office of  Technical Services, U.S. Department of Commerce.  2. 
 Kennedy, “Advanced modern radar,” Evolving  Technology Institute Short Course Notes, November 1994. 29. Work performed by L. 
 Real pulses cannot be rectangular after passing through real receiver bandwidths. The transmitting-antenna gain and receiving-antenna aperture are functions of the elevation and azimuth angles: G, = G,(e,4>) Ar = A,(e,4>) (12.2«) The differential scattering cross section itself is a function of both look angle and ground location: cr° = a°(0,(t),location) (12.26) The integral of Eq. (12.1) must be inverted when cr° is measured. 
 GROUND ECHO  16.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Near-Vertical Problem.  Most published radar return data purporting to include  vertical incidence give vertical-incidence scattering coefficients that are too small.  This is a consequence of a fundamental problem in measuring near the vertical with  a finite beamwidth or pulse length. 
 antenna servo provide a predicted doppler offset. These inputs allow the TACCAR system to provide a narrow- bandwidth correction signal. Because of the noisy nature of the clutter signal, the need to have the con- trol system bridge regions of weak clut- ter return, and the requirement not to respond to the doppler shift of a true target, the control system usually tracks the azimuth variation of a spe- cific radar range interval. 
 SENSITIVE CHARACTERISTICS OF PHASE SCANNING &IGURE C SHOWS THE ARRANGEMENT !T ONE PARTICULAR FREQUENCY  ALL RADIATORS ARE IN PHASE !S THE FREQUENCY IS CHANGED  THE PHASE ACROSS THE APERTURE TILTS LINEARLY  AND THE BEAM IS SCANNED &REQUENCY 
 SUS SIGNAL 
 POLYNOMIALSPECTRU VCV  LN  S MMWITH   
 19, R. C. Johnson  and H. 
  D"  SIDELOBE PROVIDES CHAFF REJECTION TO  o "ECAUSE OF THE CONSTRAINT OF HAVING ONLY FIVE  ZEROS AVAILABLE  THIS FILTER COULD NOT PROVIDE  
 ROW   OR TO RECOGNIZE ONE CLASS OF TARGET FROM ANOTHER A CRUISE SHIP RATHER THAN A TANKER   7HEN USED FOR MILITARY PURPOSES  IT IS USUALLY CALLED A  NONCOOPERATIVE TARGET RECOG 
  PHASED ARRAY RADAR  ON A ROTATING PEDES 
 As will be shown, the variation can be quite rapid, especially for targets many wavelengths in size. The echo characteristics depend in strong measure on the size and nature of the target surfaces exposed to the radar beam. The variation is small for electri- cally small targets (targets less than a wavelength in size) because the incident wavelength is too long to resolve target details. 
 FIRST 
 The noise and signal shown, incidentally, were derived from alineardetector. Inthe case ofanintensity-modulated indicator with apersistent screen, what wehave called “integration” isvery nearly exactly that— namely, the repeated addition, and hence averaging, ofanumber of successive sweeps. The difference isthat the number ofsweeps soaver- aged isnot sharply defined, since the luminosity ofthe screen decays gradually with time. 
 PROCESSED TO PRODUCE CROSSRANGE RESOLUTION FINER THAN THAT PROVIDED BY THE REAL BEAM ALONE BROADSIDE CROSSRANGE RESOLUTION IS  y 2K , $"3  WHERE ,$"3 IS THE SYNTHETIC APER 
 TION BY EMPLOYING AN EXTENDED HARMONIC OR &OURIER SERIES ANALYSIS 4HE 6!$ HAS BEEN IMPLEMENTED ON THE .EXRAD AS A STANDARD PRODUCT THAT CAN BE USED IN PRECIPITATION AND . 
       &)'52%   #ASSEGRAIN DUAL REFLECTOR ANTENNA SYSTEMS  THE LARGER SURFACE IS THE MAIN REFLECTOR  AND THE SMALLER SURFACE IS THE SUBREFLECTOR   A  RAY OPTICS  B  TYPICAL AXIAL CONFIGURATION  AND C   OFFSET CONFIGURATION.   2%&,%#4/2 !.4%..!3   £Ó°ÓÎ 4HE MAGNIFICATION  M IS A USEFUL METRIC IN THAT  IT PROVIDES A MEASURE OF THE REDUCTION IN  SIZELENGTH ALONG THE FOCAL AXIS THAT IS ENABLED BY USE OF THE #ASSEGRAIN REFLECTOR SYSTEM  IN LIEU OF A SINGLE PARABOLIC REFLECTOR SYSTEM 4HE FEED IS DESIGNED TO PRODUCE SUITABLE ILLUMINATION WITHIN SUBTENDED ANGLES o X R ASSOCIATED WITH THE LONGER FOCAL LENGTH FC !PERTURE BLOCKING CAN BE LARGE FOR CENTER 
 ,INCOLN ,ABORATORY   4HE ADVANTAGE OF SYSTOLIC  IMPLEMENTATION IS HIGH PROCESSING SPEED AND COMPACT  LOW WEIGHT  LOW POWER CON 
 POWER ACTIVE 
 Bythetime thesetwas built and ready foruse, theneed foritinits originally planned role asalong-range air-warning sethad nearly dis- appeared. The usefulness ofsuch aset incontrolling offensive air operations was just beginning toberealized (Sec. 7“6). 
 The uncontrolled transfer ofenergy between compressional and transverse modes will give rise topulse distortion and multiple echoes. Such difficulties may occur attheboundaries ofthematerial or atpoints ofinhomogeneity. Since sound velocity insolids isgreater than that inmercury byafactor ofabout 4,thebeam spread isgreater and the delay path longer. 
 CESS BECAUSE THEIR CODING DOES NOT MATCH THAT OF THE WANTED SIGNAL )N PULSE DOPPLER APPLICATIONS  SPURIOUS SIGNALS ARE OF MUCH GREATER CONCERN BECAUSE THEY CAN CREATE COMPONENTS WITH DOPPLER AT A VARIETY OF FREQUENCIES THAT MAY NOT BE REJECTED BY THE CLUTTER FILTERING 3IGNAL 
 ICE IN THE 7EDDELL 3EA  !NTARCTICA v  )NTERNATIONAL *OURNAL OF 2EMOTE 3ENSING    VOL   PP     & 4 5LABY AND # %LACHI   2ADAR 0OLARIMETRY FOR 'EOSCIENCE !PPLICATIONS  "OSTON !RTECH  (OUSE  .   '2/5.$ %#(/  £È°ÈÎ  - ! 3LETTEN AND $ * -C,AUGHLIN  h2ADAR POLARIMETRY v IN  7ILEY %NCYCLOPEDIA OF %LECTRICAL  AND %LECTRONICS %NGINEERING /NLINE   * 7EBSTER ED   .EW 9ORK *OHN 7ILEY  3ONS  )NC     * VAN :YL AND 9 +IM  h2EMOTE SENSING BY RADAR v IN  7ILEY %NCYCLOPEDIA OF %LECTRICAL AND  %LECTRONICS %NGINEERING /NLINE  * 7EBSTER ED   .EW 9ORK *OHN 7ILEY  3ONS  )NC    7 - "OERNER ET AL  h/N THE BASIC PRINCIPLES OF RADAR POLARIMETRY THE TARGET CHARACTERISTIC  POLARIZATION STATE THEORY OF +ENNAUGH  (UYNENS POLARIZATION FORK CONCEPT  AND ITS EXTENSION TO  THE PARTIALLY POLARIZED CASE v 0ROC )%%%  VOL   PP n    * * VAN :YL  ( :EBKER  AND $ . (ELD  h)MAGING RADAR POLARIZATION SIGNATURES 4HEORY AND  OBSERVATION v 2ADIO 3CI  VOL   PP n    3 ! -ORAIN AND $ 3 3IMONETT  h+ 
 17.33  17.7 Range Performance  ...............................................  17.33  Range Equation  .................................................  17.33 System Losse s  .................................................. 
 29. P. Meischner (ed.), Weather Radar: Principles and Advanced Applications , Berlin: Springer- Verlag, 2004. 
 For p 1, the gain is reduced 75 percent, the half-power beamwidth is  72.61/D, and the first sidelobe is 24.6 dB below the maximum. The sidelobe level is 30.6 dB  down for p = 2, but the gain relative to a uniform distribution is 56 percent. Additional  properties of this distribution can be found in Ref. 
 ATMOSPHERIC FLIGHT  AND ENDO 
 Covering the plate with magnet icmaterial oflow refractive index not only reduces the principal diffraction maximum, but also makes the secondary maxima considerably lower. Generally speaking, material ofhigh refractive index can beexpected toreduce thespecular cross section while itleaves thediffraction cross section substantially unaltered. Magnetic material oflow refractive index may, however, also effect areduction inthe diffraction cross section. 
 24, pp. 371-391, April, 1953; also letters to the editor by D. Middleton et al. 
 ,OOKING !IRBORNE 2ADAR 3,!2   3,!2 CONSISTED OF AN AIRCRAFT 
 Because of the complexity of this representation and others for polarimetric signals,  one cannot as readily provide curves of response as for single-polarization images.  Hence, we do not find many catalogs of polarimetric scattering responses. Nevertheless, many authors have described the use of polarimetric images. 
 System considerations. Tlle potential advantages claimed for solid-state sources in radar may  he summarized as (1) long, failure-free life, (2) low transmitter voltage, which eliminates the  risk of X-rays and electric sl~ock. (3) amplitude control of the transmitted waveform by selec-  tively switclling rnodules or itldividi~al devices on or off, (4) wide bandwidth, (5) low projected  volttme-production costs, and (6) air coolitlg. 
 LIMITED SAMPLES HAVE AN IMPROVEMENT  FACTOR LESS THAN  D"  WHEREAS ALMOST  OF THE SAMPLES EXCEE D THE ) EXPECTED FOR  A LINEAR SYSTEM.   -4) 2!$!2  Ó°È£ 4HE TIME 
 Inorder toseparate the pulse signals from thevideo signals atthereceiver, ifamplitude selection cannot beused, thetwo arepassed alternately through video switch b,which is controlled byflip-flop c.Initsnormal position, the latter causes the switch topass signals from thecoders. When theflip-flop istriggered by thepulse to;the modulator, the switch isreversed and video signals are passed until the flip-flop spontaneously returns toitsinitial condition, shortly before thenext basic pulse, and opens thechannel topulses again. Ifthe transmitter issuch that the pulses can betransmitted atseveral times thelevel ofthevideo signals, this switching need not bedone since amplitude discrimination can then beused atthereceiver. 
 41.McKee. D.A.:AnFMMTICancellation System,MITLincolnLab.Tech.Rept.171,Jan.8,1958. 42.Meuehe, C.E.:DigitalSignalProcessor forAirTrafficControl Radars,IEEENEREM 74Record, Part4:RadarSystemsalldCompollellts, pp.73-82.Oct.28-31,1974,IEEECatalog no.74CHO934-0 NEREM. 
 28 to  May 6. 1977.  { . 
 Here the important general - izable lesson is that an increase in number of looks can be applied to offset a decrease  in range resolution (within reason and in this kind of exploratory space-based SAR  data). Note that both looks and resolution require support in bandwidth. It follows  that QSAR is proportional to the product of the range and azimuth bandwidths, hence  proportional to the (two-dimensional) information capacity of the radar in the Shannon  sense. 
 (The definition of CT° in HF radar is complicated by problems in properly defining antenna gains for ground-wave and sky-wave paths and by propagation effects due to the ionosphere.) The clutter spectrum tends to fill in around and between the lines as the wind picks up. For horizontal polarization (which is pos- sible only over sky-wave paths), the cross section is much smaller and shows the characteristic fourth-power decay with decreasing grazing angle. For these HF wavelengths of tens of meters, the sea is relatively flat and the scattering laws are simple. 
 P. Hartl, M. Reich, and S. 
 TION INCREASES  &ORTUNATELY  THE RANGE PULSE HAS SUFFICIENT BANDWIDTH USUALLY MORE  THAN  -(Z  SO THAT MUTUALLY COHERENT RANGE BANDWIDTHS CAN BE CHOSEN FROM THE DATA AT THE TIME OF PROCESSING ,OSS OF MUTUAL COHERENCE THROUGH INCREASING ORBIT SPACING IS KNOWN AS  BASELINE DECORRELATION  /NE MAY SHOW FOR REASONABLY LEVEL TERRAIN THAT  THE UPPER BOUND CONSTRAINT ON THE DIFFERENCE  $P 2AD IN ELEVATION ANGLE BETWEEN THE TWO  ORBITS IS $PP2AD 2AD LTAN  R2  WHERE R2 IS SLANT RANGE RESOLUTION  WHICH IS INVERSELY  PROPORTIONAL TO RANGE BANDWIDTH  !LERT )N THE 3!2 INTERFEROMETRIC LITERATURE  IT IS  CUSTOMARY TO USE ELEVATION ANGLE  DEFINED AS THE ANGLE BETWEEN THE RADAR LINE OF SIGHT AND THE %ARTH RADIUS VECTOR  AS SEEN FROM THE RADAR  &OR TYPICAL LARGE TIME 
 Zehner, “Bistatic sea clutter return near grazing incidence,” in IEE Int.  Conf. Radar 82 , Publication No. 
 -" 1/"  -EDIUM AND HIGH 
 Katz, I., and L. M. Spetner: Two Statistical Models of Radar Return, IRE Trr~t~s., vol. 
 If the time samples are correlated, the rank detector will not yield CFAR. A mod- ified rank detector, called the modified generalized sign test (MGST),26 maintains a low Pfa and is shown in Fig. 8.21. 
 There is one main transmitter site at Lake Kickapoo, Texas, with smaller aux- iliary sites in GiIa River, Arizona, and Jordan Lake, Alabama. The transmitter sites are phased array dipole antennas driven through a coaxial corporate-feed system. The main transmitter site at Lake Kickapoo consists of 2556 antenna el- ements, each driven by a 300-W solid-state module located directly below the an- tenna. 
 C. Cooper: An Analysis of the Performance of Weighted Integrators, IEEE  Trans., vol. IT- 10, pp. 
 Figure 2.15. Remote indicating unit in the nose of a Hudson [ 7]. Figure 2.16. 
 L  the 90° phase shift that results between the signals in ports 2 and 3 will produce a beam  oriented in a direction 30° to the right of the array normal. A signal in port No. 4 results in  0.701 V !St  0.707 V /90°  0  CD  l V /S),0  Righi beom 0  1v&  Left beam Figure 8.27 3-dB directional coupler generating two beams  from a two-element array. 
 24.6b, SNR = Pr - N = - 147 + 153 = 6 dB And if 10-s coherent processing time is used, SNR = 16 dB Figure 24.29 provides a display of a 13-kn target and the sea echo as seen by a ground-wave radar. This is a family of received power versus doppler fre- quency plots over seven operating frequencies and for a target both approaching and receding. The abscissa units are in doppler normalized to the resonant wave or Bragg frequency; therefore, the resonant wave responses peak at ± 1. 
 Time-delay scanning is independent of frequency. Delay lines are used instead of (d) FIG. 7.2 Generation of scanned beams, (a) Phased array, (b) Time-delay array, (c) Frequency- scanned array, (d) Blass-type array.0-27TPHASE SHIFTERSVARIABLETIMEDELAYS (a)(b) (c)BEAM NO. 
 88.Mitchell, R.L.,andJ.F.Walker: Recursive Methods forComputing Detection Probabilities, IEEE Trans.,vol.AES-7,pp.671-676, July,1971. 89.Gupta,D.V.,J.F.Vetelino, T.J.Curry,andJ.T.Francis: AnAdaptive Threshold Systemfor Nonstationary NoiseBackgrounds, IEEETrans.,vol.AES-13, pp.11-16,January, 1977. 90.Preston, G.W.:TheSearchEfficiency oftheProbability RatioSequential SearchRadar,IREIntern. 
 A. Fabrizio (DSTO, Australia), Dr. U. 
 Linde, and K. Meads, “Senrad: an advanced wideband air-surveillance radar,”  IEEE Trans ., vol. AES-37, pp. 
 GE-24, pp. 453–461, 1986. 104. 
 The broadside arrays comprised a transmitting aerial on the top of the fuselage and tworeceiving arrays, one on each side of the aircraft. The transmitting array typically comprised four pairs of dipoles, supported on masts. The receiving array was four pairs of dipoles mounted on each side of the aircraft. 
 PLER OBSERVATIONS AND  THEREFORE  TO OBTAIN VECTOR WINDS "ECAUSE THE AIRCRAFT NEED NOT FLY ORTHOGONAL TRACKS  THE TIME REQUIRED FOR MEASUREMENTS OF CLOUD SYSTEMS IS DRAMATI 
 OPULSE RADARS SUSCEPTIBILITY TO TARGET GLINT OR MULTIPATH SIGNALS  /NE JAMMING APPROACH  KNOWN AS  CROSS 
 One ad- vantage of mutual-support jamming is the greater ERP available from a collection of platforms in contrast with a single platform. However, the real value of mutual-support jamming is in the coordinated tactics which can be employed. A favorite tactic employed against tracking radars, for example, is to switch be- tween jammers located on separate aircraft within the radar's beamwidth. 
 The antenna is a 1-m reflector (gain ∼40 dB), with two feeds, result - ing in a pair of pencil beams at 46 ° (H polarization) and 54 ° incidence (V polarization).  The illumination geometry also is advantageous because the incidence is the same for  all aspect angles. The beam-limited footprints are approximately 30 km by 40 km. 
 An accurate estimate of the target angle is given by 0 = 6, + Y + -L-IiI(A2W1) (8.7) where a = 1.386/(beamwidth)2 (8.8) and A1 and A2 are the two largest amplitudes of the returned samples and occur at angles O1 and O2 = O1 + A0 respectively. Since the estimate should lie between 0j and 02 and Eq. (8.7) will not always yield such an estimate, 0 should be set equal to O1 if 0 < U1 and 0 should be set equal to 02 if 0 > U2. 
 Mk. VI and A.S.V. Mk. 
 TO 
 The range coverage, although short, requires multiple overlapping  beams and multiple waveforms. One method for calculating terrain height8 is shown in  Figure 5.26. It consists of measuring the centroid and extent of each individual beam  position over many pulses and estimating the top of the terrain in each beam, as shown  in the figure. 
 W. Shrader, “MTI Radar,” Chap. 17 in Radar Handbook , M. 
 260-271, March, 1973.  148. Brennan, L. 
 BASED COSINE SQUARED  ARE COMMON 4HE SMALL VERTICALLY POLARIZED FIELDS PRODUCED BY EACH SLANTED  SLOT NEED TO BE SUP 
 Special thanks are due to Victoria Holzhauer for her careful typing, assistance with figures, and ed- iting of this manuscript. The author is also grateful to Richard Carbone and Jeffrey Keeler for their crit- ical reviews. similar to radars used for other purposes. 
 110. Domville, A. R.: The Bistatic Reflection from Land and Sea of X-Band Radio Waves, pt. 
 PLE  A FIXED MULTIBEAM RECEIVE ANTENNA CAN BE USED WITH A FIXED FLOODLIGHT TRANSMIT  ANTENNA 4HIS CONFIGURATION ALLOWS THE RECEIVER TO INTEGRATE LONGER  SUBJECT TO TARGETCELL MIGRATION LIMITS  WHICH  IN TURN  CAN RECOVER SOME OF THE LOST RANGE PERFORMANCE OF THE FLOODLIGHT ANTENNA )T ALSO HAS THE BENEFITS OF INCREASING  DATA RATES AND SIMULTANE 
  
 BEAM WIDTH MAY MAKE THE RADAR MORE VULNERABLE TO MAIN 
 R., N. C. Currie. 
 22.15.61 It is seen that the solar systems are larger than the nuclear. As the power level increases, the increased size of the solar system becomes more pronounced. In comparing overall lengths, the 100-kW solar system is 2.4 times the length of the nuclear system. 
 CURVATURE SIGNATURES    
 104, pi'. 43 52. 139 .147. 
 285–303, 1989. 144. K. 
 ON SECTOR  THE RADAR ECHO WILL BE DOMINATED BY RETURNS FROM THE ENGINE INLETS WHERE THE CHINE CONTRIBUTION IS NO DOUBT NEGLIGIBLE 7HEN SEEN FROM THE BROADSIDE ASPECTS  THE CHINE REDUCES THE SPECULAR ECHO THAT WOULD HAVE COME FROM THE OTHERWISE ROUNDED SIDES OF THE FORWARD FUSELAGE .OTE THAT THE TAIL FINS ARE CANTED INWARD  THEREBY DEFLECTING INCIDENT RADAR WAVES UPWARD AWAY FROM THE RADAR  WHEN SEEN FROM THE SIDE 4HIS DESIGN GREATLY REDUCES  THE 32 
 Thus, one or more clutter filters may suppress  multiple clutter sources located at different doppler frequencies. An example of the  use of an MTD doppler filter bank against simultaneous land and weather clutter (Wx)  is illustrated in Figure 2.9. It can be seen that filters 3 and 4 will provide significant  suppression of both clutter sources. 
 Caracena: An Analysis of Three Weather-Related Aircraft Accidents, Bull. Am. MeteoroL Soc., vol. 
 604–612,  December 1986. 22. D. 
 This necessary time intervaldetermines the highest PRR that can be used. The PRR must be high enough, however, that sufﬁcient pulses hit the target and enough echoes are returned to the radar. The maximummeasurable range can be determined approximately by dividing 81,000 bythe PRR. 
 thevelocity spectraarcslightlybroader atthelowerfrequencies. anunexpected result.25Thespectraare broader forhorizontal thanforverticalpolarization, andincrease inwidthasthesquareroot ofthewaveheightforbothpolarizations. Observation time.Intheabove.arapidantenna-rotation ratetakesadvantage ofthefactthat theclutterechochanges withtime,butthetargetechodoesnot.Withahigh-resolution radar (nanoseconds pulsewidth)theindividual sea-clutter spikes,asmentioned inSec.13.3,can persistforseveralseconds. 
 Just asthe final proof ofasatisfactory aerodynamical and electrical design are aerodynamical and electrical tests, sostructural tests are FIc.9.3S.—A retractable radome (1)partly extended onaB-29, andtbebulge toaccom. modate tber-funit(2)aftoftheradome. necessary toassure asatisfactory design, forinastreamlined shape the calculations can atbest beonly approximate. 
 IT.  Hil. CONTENTS  THE DISCOVERY OF RADAR  Pulse systems—An analogy from the animal  world—Infra-red-light photographic proof of  the bat’s supersonic ‘radar’ system—How an  early patent of John Logie Baird led the way  to radar scanning—French progress in 1933—  Contribution of the U.S. 
 Polgc: Performarice of the y-11 Filter for Tracking Maneuvering Targets,  I EEI: 7'rirrts.. vol. AI'S-10. 
 Within the heterosphere lies the  ionosphere . The bottom portion of the homosphere is called the troposphere . Troposphere. 
 DOMAIN IMPLEMENTATION OF A DIRECT DIGITAL DOWNCONVERTER             
 36.B1asbalg, H.:TheRelationship ofSequential FilterTheorytpInformation TheoryandItsApplication totheDetection ofSignalsinNoisebyBernoulli Trials,IRETrans.,vol.IT-3,pp.122-131, June, 1957. 37.Wald,A.:"Sequential Analysis," JohnWiley&Sons,Inc.,NewYork,1947. 38.Marcus, M.8.,andP.Swerling: Sequential Detection inRadarwithMultiple Resolution Elements, IRETrans.,vol.1T-8,pp.237-245, April,1962., 39.Caspers, J.W.:Automatic-detection Theory, chap.15of••RadarHandbook," M.1.Skolnik (ed.~ McGraw-Hill BookCompany, Inc.,NewYork,1970. 
 CONJUGATE SPECTRAL SYMMETRY 4HE SIGNAL SPECTRUM AFTER SAMPLING BY ITS .YQUIST FREQUENCY  " IS SHOWN IN  &IGURE B 4HERE IS NO ALIASING 4HE .YQUIST RATE IS A  MINIMUM SAMPLING FREQUENCY FOR A SIGNAL  A BOUND  AND  MEETING THE BOUND IS NECESSARY  BUT NOT SUFFICIENT  TO ENSURE THAT NO ALIASING OCCURS #ONSIDER THE CASE PRESENTED IN &IGURE  A  WHICH IS THE SAME BANDLIMITED BANDPASS  SIGNAL SHOWN IN &IGURE   BUT SHIFTED IN FREQUENCY SO THAT IT DOESNT BEGIN EXACTLY AT " 4HE SAMPLED SIGNAL  SPECTRUM IN &IGURE  B SHOWS THAT  ALTHOUGH THE SAMPLING  RATE SATISFIES THE .YQUIST BOUND  THE SAMPLED SIGNAL IS STILL ALIASED 4O SOLVE THIS PROB 
 The same procedure was carried out for the azimuth reference, with a slight more care: the antenna beam pattern estimated in this way is not always effective due to the growing attenuation and the joint inﬂuence of azimuth and range beam patterns with the slant range and the possible presence of wide strong scatterers that can reduce the quality of the estimated pattern. Also, it is not clear, in this case, where the azimuth phase history should be stopped. The main objective is to limit the phase history in a proper way to avoid azimuth aliasing. 
 The stability requirement is that the poles of the Z trans- fer function lie within the unit circle. Zeros may be anywhere. These velocity response curves are calculated for a scanning radar system with 14.4 hits per beamwidth. 
 307. Sensors 2019 ,19,6 3 T able 9. Experiment using original dataset. 
 In addition, there may be anomalous  ionization referred to as sporadic E. This latter ionization layer is typically only a few  kilometers thick and usually short-lived, often lasting less than an hour; it may be either  smooth or patchy, is seasonally and diurnally variable, weakly correlated with solar  activity, showing a tendency to favor low sunspot numbers, and has marked variation  with latitude. From the propagation perspective, sporadic E holds a special place as the  layer providing the most stable propagation over coherent integration times typical of  skywave radar. 
 "System for Detecting Objects by Radio," U.S. Patent 1.981.884. granted Nov.27.1934, to A. 
  53! n .O   ^ +Un  3EASAT 53!  ^        +U9ES  'EOSAT 53! n '-    ^   +Un  %23 
 J. Bridges and J. Feldman, “An attenuation reflectivity technique to determine the drop size  distribution of water clouds and rain,” J. 
 (collection of 38 reprints.)  43. Howard, D. D., J. 
 NULL ANTENNA BEAMWIDTH )N ONE CASE  THE GAIN RATIO  K IS OPTIMIZED AT EACH VALUE OF PULSE 
 Obviously, the choice of these scattering obstacles related  more to the preexistence of convenient scattering solutions for these shapes than to  insights gained from observing the sea. Since then, feature models have sought greater  reality by considering wedge shapes, as suggested by the sharp crests of Stokes waves  observed on most natural water surfaces12,32,92,93 and the shocks and plumes suggested  by the properties of wave groups and the hydrodynamics of breaking waves.12,57 The other approach to theoretical modeling derives the scattered field from a  global boundary-value problem (GBVP) in which the sea as a whole is considered a  boundary surface whose corrugations are described by some kind of statistical pro - cess. An enormous literature is devoted to the theory of surface scatter from this  point of view, stemming from the importance not only of radar sea scatter, but also  radar ground scatter and sonar reverberation  (the acoustic equivalent of radar clutter)  from both the surface and the bottom of the sea. 
 STATE MODULE MAY BE CONNECTED TO EVERY RADIATING ELEMENT OR TO EVERY SUBAR 
 The two wires were spaced apart by¾ inch and held ﬁrmly in place by insulating blocks. The sliding short circuit was controlled by a rotatable arm. An end-stop was adjusted for minimum attenuation, when the stub would have been a quarter wavelength long. 
 Peterson and E. J. Weldon, Jr., Error Correcting Codes , Cambridge: M.I.T. 
 24.9 SIGNAL-PROCESSING-RELATED ECCM Digital coherent signal processing greatly alleviates the effects of clutter and chaff.3,140  This is motivated by the use of coherent doppler processing techniques such as fixed,  adaptive MTI, or optimum pulse-doppler processing. Noncoherent devices are also  ch24.indd   33 12/19/07   6:00:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 CALLY OR FINANCIALLY  FEASIBLE IMPLEMENTATION -EASUREMENT 0RECISION  #LEARLY  R    MUST BE MEASURED WITH AN ACCURACY AND  PRECISION OF LESS THAN  D" IF USEFUL WIND RETRIEVALS ARE TO BE DERIVED !CCURACY DEPENDS ON THE RADARS STABILITY AND ITS CALIBRATION 4HE CHALLENGE FOR SPACE 
 Previously  undefined terms will be defined throughout the chapter. The table assumes an airborne  radar application designed to detect other aircraft. Such an application is commonly  referred to as air-to-air .Radar Application Requirements Airborne or spaceborne surveillance Long detection range; accurate range data Airborne interceptor or fire control Medium detection range; accurate range, velocity, and  angle data Ground-based surveillance Medium detection range; accurate range data Battlefield surveillance   (slow-moving target detection)Medium detection range; accurate range, velocity data Missile seeker Short detection range; accurate velocity and angle rate data;  may not need true range information Surface-based weapon control Short range; accurate range, velocity data Meteorological Good velocity resolution Missile warning Short detection range; very low false-alarm rateTABLE 4.1  Pulse-Doppler Applications and Requirements TABLE 4.2  Comparison of MTI and Pulse Doppler Radars for Air-to-Air Advantages Disadvantages Low PRF MTI range unambiguous doppler ambiguousCan sort clutter from targets on basis  of range. 
 BAND DESIGNATION FOR MILLIMETER WAVE RADARS IS  MM  AND THERE  ARE SEVERAL FREQUENCY BANDS ALLOCATED TO RADAR IN THIS REGION  BUT THEY HAVE NOT BEEN LISTED HERE !LTHOUGH THE OFFICIAL )45 DESCRIPTION OF MILLIMETE R WAVES IS FROM  TO   '(Z  IN REALITY  THE TECHNOLOGY OF RADARS AT + A BAND  IS MUCH CLOSER TO THE TECHNOLOGY  OF MICROWAVE FREQUENCIES THAN TO THE TECHNOLOGY OF 7 BAND 4HE MILLIMETER WAVE RADAR FREQUENCIES ARE OFTEN CONSIDERED BY THOSE WHO WORK IN THIS FIELD TO HAVE A LOWER BOUND OF  '(Z RATHER THAN THE hLEGALv LOWER BOUND OF  '(Z IN RECOGNITION OF THE SIGNIFICANT DIFFERENCE IN TECHNOLOGY AND APPLICATIONS THAT IS CHARACTERISTIC OF MILLIMETER WAVE RADAR  -ICROWAVES HAVE NOT BEEN DEFINED IN THIS STANDARD  BUT THIS TERM GENERALLY APPLIES TO  RADARS THAT OPERATE FROM 5(& TO + A BAND 4HE REASON THAT THESE LETTER DESIGNATIONS MIGHT  NOT BE EASY FOR THE NON 
 In this version the greater of the outputs from the range cells ahead or  or behind the cell of interest is used to set the threshold.  loss with a conventional cell-averaging CFAR is 0.8 dB. With the «greater-of" technique the  loss is increased to I. 
 NOISE OUTPUT  OF THE -4) RECEIVER RELATIVE TO THE SIGNAL 
 The technique to accomplish this was initially  called simultaneous lobing , which was descriptive of the technique. Later, the term  monopulse  was coined, referring to the ability to obtain angle error information on  a single pulse. It has become the commonly used name for this tracking technique;  even though, the lobes are generated simultaneously and monopulse  tracking can be  performed with CW radar. 
 ROLOGICAL RADARS BY TECHNOLOGICAL AND SCIENTIFIC LEADERS &INAL LY  PERHAPS THE BROADEST AND  MOST COMPLETE SET OF REFERENCES ON PROGRESS IN THE FIELD CAN BE FOUND IN THE SERIES OF  0ROCEEDINGS AND 0REPRINTS OF THE )NTERNATIONAL  #ONFERENCES ON 2ADAR -ETEOROLOGY  SPONSORED BY THE !MERICAN -ETEOROLOGICAL 3OCIETY !-3  4HESE DOCUMENTS CAN BE FOUND IN MANY TECHNICAL LIBRARIES AND ALSO CAN BE OBTAINED ONLINE )N ADDITION  THE 0ROCEEDINGS OF THE %UROPEAN #ONFERENCES ON 2ADAR -ETEOROLOGY  PROVIDES EXCELLENT  REFERENCE MATERIAL £°ÓÊ / 
 EYE JAMMING IN  SEEKER HEAD APPLICA 
 STATE TRANSMITTER RESULTS IN COMPROMISES THAT HAVE  TO BE MADE IN THE DESIGN OF THE OVERALL RADAR SYSTEM /SCILLATOR 6ERSUS !MPLIFIER  4HE POWER AMPLIFIER IS OFTEN PREFERRED OVER THE  POWER OSCILLATOR AS THE TRANSMITTER POWER SOURCE IN HIGH POWER  HIGH PERFORMANCE  RADAR SYSTEMS )N AN AMPLIFIER  THE SIGNAL TO BE TRANSMITTED IS PRECISELY GENERATED AT A LOW POWER LEVEL AND IS THEN AMPLIFIED TO ACHIEVE THE REQUIRED POWER TO BE RADI 
 A. Green, “Radar detection probability with logarithmic detectors,” IRE Trans ., vol. IT-4,  March 1958. 
 4  .   ")34!4)# 2!$!2   ÓÎ°Îx   - -ATSUO ET AL  h"ISTATIC RADAR CROSS SECTION MEASUREMENTS BY PENDULUM METHOD v  )%%%  4RANS  VOL !0 
 In addition to the ferrite and diode devices, there have been  other techniques suggested for electronically varying the phase shift. The traveling-wave tube . TIIF FI.FCTRONICAI.I Y STFFRED PHASED ARRAY ANTENNA IN RADAR 297  can provide a rast. 
 SIZE DISTRIBUTION REPRESENTS A BETTER FIT TO INSTANTANEOUS  NATURAL VARIATIONS OF THE DROP 
 This is accomplished by turning off the transmitter after enough pulses  have been collected to satisfy the azimuth resolution requirement. Each such burst has  an instantaneous doppler corresponding to the antenna beamwidth (which determines  the Nyquist PRF limit), but a shorter synthetic aperture length. Burst mode is standard  ch18.indd   23 12/19/07   5:14:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Because this class of operation is inherently nonlinear, as  the transistor modulates between being off and saturated through each RF cycle, the  harmonic content is high, and appropriate filtering of undesired higher order spec - tral content must be applied at the output of the transmitter. The amplifier Class-D,  -E, -F, and -G are high efficiency switching amplifier configurations that require  specialized termination of the signal harmonics (filtering) in order to maximize the  amplifier efficiency. These can be complicated hardware implementations but may  be warranted where incremental improvement in efficiency brings benefit to the  transmitter system. 
 SURFACE SLOPE MEASUREMENT PROBLEM IS CHALLENGING BECAUSE THE DESIRED SLOPE SIGNALS ARE AS SMALL AS ONE MICRORADIAN  EQUIVALENT TO A  MM HEIGHT DIFFERENTIAL RISE  FOR EACH  KM ALONG 
 13,   pp. 357–364, 1978. 149. 
 M. Santa “Final report on anticlutter techniques,” General Electric  Company Rept. R65EMH37, March 1, 1953. 
 al\ h 5, Eq. (7.15) gives a beamwidth that is too narrow, the error being less than 7 percent. When the beam is scanned to very large scan angles, toward endfire, more exact calculations become necessary.42'45 Equation (7.8) still applies and gives, for endfire with isotropic radiators, QB (endfire) = 2 Ap**£- rad (7.16)V a/X Element Factor and Gain of Planar Arrays. 
  
 The same illumination functions  used in antenna design to reduce spatial sidelobes can also be applied to the frequency domain  to reduce the time sidelobes in pulse compression. A comparison of several types of spectral  weighting functions is shown in Table 1 1. 1.16*2Jb25 The Taylor weighting with n = 8 means the  peaks of the first 7 sidelobes (Ti - 1) are designed to be equal, after which they fall off as Ilt. 
 NIQUES v )%%% 4RANS 'EOSCI 2EM 3ENS  VOL   PP n    * # (UBBERT  6 . "RINGI  AND $ "RUNKOW  h3TUDIES OF THE POLARIMETRIC COVARIANCE MATRIX  0ART ) #ALIBRATION METHODOLOGY v * !TMOS /CEAN 4ECHNOL   VOL   PP n    2ADAR CALIBRATION WORKSHOP PRESENTED AT  ST  !NNUAL  -EETING  OF  THE  !M  -ETEOROL  3OC    !LBUQUERQUE    2 * +EELER AND 2 % 0ASSARELLI  h3IGNAL PROCESSING FOR ATMOSPHERIC RADARS v #HAPTER  IN  2ADAR  IN -ETEOROLOGY  !TLAS ED   "OSTON !-3    PP n  * 3 -ARSHALL AND 7 (ITSCHFELD  h4HE INTERPRETATION OF THE FLUCTUATING ECHO FOR RANDOMLY DISTRIB 
 RELATIVE SYSTEM TO IDENTIFY FIXED NAVIGA 
 means ofwaveguide. Rigid coaxial lines arenot ordkarily used forwavelengths below 8cm because the limitation onover-all size just mentioned permits too low a maximum power-carrying capacity. However, astandard ~-in. 
 Similarly, the scanned beamwidth is increased from the broadside beamwidth (except in the vicinity of endfire, G0 = 90°): G#(broadside)0o (scanned) ~cos G0 The total number of beams M (with broadside beamwidth and square stacking) that fit into a sphere is approximately equal to the gain and with r\ ~ 1 is thus simply related to N by M-TTN In a planar array where the beamwidth changes with the scan angle, the number of beams that can actually be generated and fitted into a sphere is M' ~|;v An array where the elements are fed in parallel (Sec. 7.8) and which is scanned by phase shift, modulo 2ir, has limited bandwidth since for wideband operation constant path lengths rather than constant phases are required. The limit is given by Bandwidth (%) ~ beamwidth (deg) This is equivalent to limitations given by Pulse length = 2 x aperture size With these criteria, the scanned radiation pattern at 60° is steered by ± one- fourth of the local scanned beamwidth as the frequency is changed over the band. 
 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 Automatic Detection,  T racking, and Sensor  Integration W. 
 Both the loss in  performance and the difficulty in obtaining large isolations have limited the application of the  hybrid junction to short-range radars.  Ferrite isolation devices such as the circulator do not suffer the 6-dB loss inherent in the  hybrid junction. Practical devices have isolation of the order of 20 to 50 dB. 
 Heimiller, A. F. Fromm, E. 
 Sensors 2019 ,19, 2161 the steering of antenna, the beam central incident angle θivaries within the acquisition time and is determined by the instant squint angle θsq(η). The relationship is given as follow θi=arccos/parenleftbig cos(θi0)·cos/parenleftbig θsq(η)/parenrightbig/parenrightbig(1) Figure 1. The observation geometry of sliding spotlight SAR with ionosphere. 
 Atmosfieric ducts are generally of the order of 10 or 20 meters in height, never more than  perhaps 150 to 200 meters. Propagation within a surface duct is similar to propagation within  a waveguide with a "leaky top wall." A duct supports only certain modes of propagation and  does not readily support propagation below a critical wavelength. A simplified approximate  model of propagation in atmospheric ducts gives the maximum wavelength that can be pro-  pagated in a surface duct of depth d as2"  wtiere A,,,, Ah, and d are in the same units. 
 Asignificant reduction inweightcanbeobtained insometubesby replacing thesolenoid withaperiodic-perm anent-magnetic (PPM)focusing systemwhichcon­ sistsofaseriesofmagnetic lenses.PPMfocusing isnotsuitedtolargeaverage-power tubes.At Xband,themaximum average powerisprobably underakilowatt.8Insomeklystrons the electron beammaybeconfined byelectrostatic fieldsdesigned intothetubestructure sothat external magnets arenotrequired.40 Inahigh-power klystron, from2to5percentofthebeampowermightnormally be intercepted bytheinteraction structure, orbodyofthetube.Ifthebeamwerenotproperly confined inahigh-power klystron, thestrayelectrons thatimpinge uponthemetalstrucll:re of thetubewouldcauseittooverheat andpossibly bedestroyed. Sincelossofthefocusing magnetic fieldcouldcausethetubetofail,protective circuitry isnormally employed toremove thebeamvoltageintheeventofimproper focusing orthecomplete lossoffocusing. The collector ofmosthigh-power klystrons isinsulated fromthebody(RFinteraction circuit)of thetubesoastoallowseparate metering andoverload protection forthebodycurrentandthe collector current. 
 133.- 139, January,  1958.  27. Blore, W. 
 However, it introduces problems of its own. Cross-polarization lobes are produced by the  offset geometry, which tnay seriously deteriorate the radar system performance.'~17 Also, it is  usually niore difficult to properly support and to scan an offset-feed antenna than a circular  paraboloid with rear feed.  j'/D ratio. 
 TO 
 Ternes. C. L.: Sidelobe Suppression in a Range-Channel Pulse-Compression Radar, IRE Trans .. 
 Curves 3,4, and 5 are similar to curve 2, except  that they apply to a free-space signal of 110, 55, and 27.5 nautical miles, respectively. Curve 6  Figure 12.8 Contours of "radar  coverage" for radar height of 200 ft  above curved earth. (1) Geometrical  line-of-sight contour for k = 3; (2)  constant-radar-signal contour in the  diffraction region, assuming a radar  capable of a free-space range of 220  nrni, vertical polarization, seawater,  k = j,f= 500 MHz; (3) same as (2),  but for 110 nrni free-space range;  (4) same as (2). 
 Walker: Recursive Methods for Computing Detection Probabilities, IEEE  Trans., vol. AES-7, pp. 671-676, July, 1971. 
 R. F. Harrington, Field Computation by Moment Methods , New York: Macmillan Company,  1968. 
 Simpson and G. L. Tyler, “Reanalysis of Clementine bistatic radar data from the lunar  South Pole,” J. 
 Delta alluvial and silt plain dominates the topography of the area. Due to these geological characteristics, the subgrade of the highway is extremely prone to liquefaction and seismic subsidence. For this reason, long-term stability monitoring of this area is critically necessary. 
 Fox, J. (ed.): "Proceedings of the Symposium on Submillimeter Waves," Polytechnic Press of the  Polytechnic Institute of Brooklyn, Brooklyn, New York, 1971.  84. 
 This is  usually negligible for most spotlight SAR applications but might not be negligible  when collection angles are large, such as for the case of foliage-penetration SAR  (Section 17.8). The synthetic aperture time  tA required to collect the data for a spotlight SAR image  is found as follows:  δλ λ λ λcr SA sq sq≈ ≈ = ≈2 2 2 ∆q q qR LR Vt tRA Acos( ) c os( ) 2 2Vδcr sq cos( )q (17.6) where V is the platform speed. Interferometric SAR. 
  
 The coherent detector  provides a translation of the carrier frequency to direct current. It does not extract the  modulation envelope and is a truly linear detector, whereas the " linear" envelope detector was  not linear in the same sense. Therefore the coherent detector will be a more efficient detector,  especially when signal-to-noise ratios are low. 
 TIONAL SYSTEMS  THESE REFLECTOR SYSTEMS ARE LIKELY TO BE PART OF SOME NEXT 
 THE 
 Often normal  bistatic operation excludes this region, so that a 10—20°  wedge with the apex at the receiver and directed at the transmitter is excised from the  oval. Details are given in Willis.1 Figure 23.2 shows four cases of ovals of Cassini normalized to the benchmark  range: ( a) benchmark: L = 0; (b) one-oval: L < 2RM; (c) lemniscate: L = 2RM; and   (d) two-ovals: L > 2RM. In all cases, the transmitter is located at the left oval focus (0). 
  WATTS )F THE RADIATED  POWER IS  WATTS ONE MEGAWATT   THE RATIO OF ECHO SIGNAL POWER FROM A TARGET TO THE  RADAR TRANSMITTER POWER IN THIS EXAMPLE IS n  OR THE RECEIVED ECHO IS  D" LESS  THAN THE TRANSMITTED SIGNAL 4HAT IS QUITE A DIFFERENCE BETWEEN THE MAGNITUDE OF THE TRANSMITTED SIGNAL AND A DETECTABLE RECEIVED ECHO SIGNAL 3OME RADARS HAVE TO DETECT TARGETS AT RANGES AS SHORT AS THE DISTANCE FROM BEHIND  HOME PLATE TO THE PITCHERS MOUND IN A BASEBALL PARK TO MEASURE THE SPEED OF A PITCHED BALL   WHILE OTHER RADARS HAVE TO OPERATE OVER DISTANCES AS GREAT AS THE DISTANCES TO THE NEAREST PLANETS 4HUS  A RADAR MIGHT BE SMALL ENOUGH TO HOLD IN THE PALM OF ONE HAND OR LARGE ENOUGH TO OCCUPY THE SPACE OF MANY FOOTBALL FIELDS 2ADAR TARGETS MIGHT BE AIRCRAFT  SHIPS  OR MISSILES BUT RADAR TARGETS CAN ALSO BE  PEOPLE  BIRDS  INSECTS  PRECIPITATION  CLEAR AIR TURBULENCE  IONIZED MEDIA  LAND FEATURES VEGETATION  MOUNTAINS  ROADS  RIVERS  AIRFIELDS  BUILDINGS  FENCES  AND POWER 
 287-290, March, 1976.  49. Blake, L. 
 If incorporated in a radar, provision should be  included for switching it out of the receiver when it does more harm than good.J  A co11stallt false-alarm rate (CF AR) receiver is used with automatic detection systems to  keep the false-alarm rate constant as the noise level at the receiver varies (Sec. HU). Without  CF AR the computer in automatic systems can quickly become overloaded and cease to  function. 
 The use of  circular polarization to reduce the radar echo from symmetrical raindrops relative to the echo i 4  from aircraft, as described in Sec. 13.8, takes advantage of the differences in target response to  different incident polarizations.  For complete knowledge of the effect of polarization, the polarization matrix must be  determined. 
 Brunfeldt, and F. T. Ulaby, “Performance analysis of the MAS (Microwave  Active Spectrometer) systems: calibration, precision and accuracy,” University of Kansas,  Remote Sensing Lab., vol. 
 SCATTERING MEDIA ARE RECIPROCAL -OST MEDIA ARE RECIPROCAL %XCEPTIONS ARE GYROTROPIC MEDIA  SUCH AS FERRITE MATERIALS AND THE IONOSPHERE "ISTATIC 2#3 2EGION  4HE BISTATIC ANGLE AT WHICH THE EQUIVALENCE THEOREM FAILS  TO PREDICT THE BISTATIC 2#3 IDENTIFIES THE START OF THE SECOND BISTATIC REGION )N THIS REGION  THE BISTATIC 2#3 DIVERGES FROM THE MONOSTATIC 2#3 +ELL  IDENTIFIED THREE  SOURCES OF THIS DIVERGENCE FOR COMPLEX TARGETS AND FOR A TARGET ASPECT ANGLE FIXED WITH RESPECT TO THE BISTATIC BISECTOR 4HESE SOURCES ARE   CHANGES IN RELATIVE PHASE BETWEEN DISCRETE SCATTERING CENTERS    CHANGES IN RADIATION FROM DISCRETE SCATTERING CENTERS  AND   CHANGES IN THE EXISTENCE OF CENTERSAPPEARANCE OF NEW CENTERS OR DISAPPEAR 
 An example of the velocity response of a clutter map including such spreading is  shown in Figure 2.92. The range extent of the clutter map cell is 5 µs, the radar reso - lution cell is 1 µs, n = 4 pulses are noncoherently integrated, the filtering constant is  a  = 0.125, the update interval is 5 s, and the SNR = 20 dB. On each scan, the clutter  map cell is updated with the radar amplitudes in the five range cells falling within  the clutter map cell and with the amplitude from one additional radar resolution cell  before and after the clutter map cell.FIGURE 2.90  Universal curve for determining detectability loss caused by the  clutter map FIGURE 2.91  Transient response of clutter map due to  Swerling Case 2 point clutter model ch02.indd   86 12/20/07   1:47:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Heating is the chief effect of microwave radiation on living tissue. In controlled dosages,  radiation heating is beneficial and forms the basis of diathermy, a therapeutic heating of the  tissue beneath the .skin. Frequencies ranging from HF to microwaves have been used for  diathermy.",Xhe heating eflects of microwave radiation have also been applied commercially  in the form of microwave ovens, used for cooking food rapidly. 
 In the ensuing discussion, the design principles, driven by the requirements  forced by the threat, are mainly addressed.3 ch24.indd   37 12/19/07   6:00:49 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 11.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 11.5 DESIGNING FOR THE SOLID-STATE  PHASED ARRAY TRANSMITTER In contrast to the design of the solid-state bottle transmitter where significant losses can  accrue in the combining circuitry, the solid-state phased array antenna uses individual  transmit/receive (T/R) modules with internal phase shift capability. Each T/R module  is located behind an associated radiating element in a two-dimensional array. 
 losswithaconventional cell-averaging CFARis0.8dB.Withthe"greater-of" technique the lossisincreased to1.1dB.7S) Typically thenumberoftapsusedinacell-averaging CFARmightvaryfrom16to20. TheCFARmaybethought ofasusingtheoutputs ofthesampled cellstoestimate the unknown amplitude ofthebackground noiseorclutter.Because ofthefinitenumberof samples, thebackground isnotcompletely knownandalossoccurscompared totheideal detector. Forexample, whenonly10independent samplesareused,alossof3.5dBissaidto resultforaprobability ofdetection of0.9andprobability offalsealarmof10-6,whenthe background isbroadband noiseorclutterwithaRayleigh probability density. 
 Knittel (eds.), Artech House. Inc .. 1972, pp. 
 LEVEL CHANGE OVER A  
 Shaping ofaradar beam toreduce toasatisfactorily low value the percentage ofenergy striking the surface becomes impractical at wavelengths about 25cm. Atshort wavelengths (10 cmorbelow), the angular separation between lobes issmall. Loss oftracking due tonulls will normally occur only over short track distances and will notbeasserious asit isforlong wavelengths. 
 The transmitter receiver (T2R) comprised the magnetron transmitter, receive mixer and a ﬁrst stage of IF ampli ﬁcation. The local oscillator, a klystron, was housed in the indicator unit, together with the PPI and height tube displays. The master clock was the waveform generator. 
 On the other hand, the adaptive array allows one  to obtain certain lowered sidelobes simultaneously to jamming nulling. Concerning  the practical applicability of adaptive arrays some considerations follow. A num - ber of operational radar systems are adaptive; they are described in the technical  literature.38–40,102 A modern radar with digital processing already has at least four  digital channels (sum, difference in azimuth, difference in elevation, and guard). 
     AND  RADARS HAVE DEMONSTRATED MULTIFUNCTIONALITY IN COMBAT  (OWEVER  MULTIFUNCTIONALITY IS FACILITATED BY !CTIVE %LECTRONICALLY 3CANNED  !NTENNA !%3!  ARRAYS 4HE MULTIFUNCTIONAL !%3! RADAR IN THE &! 
 When receiving beams are formed in networks placed after  the RF amplifiers, as in Fig. 8.25, the antenna is sometimes called a po.stattiplijcatiori heuw  fort?tirly urray, abbreviated PABFA. A separate transmitting antenna may be used to illumin-  ate the volume covered by the multiple receiving beams or, alternatively, it is possible to  transmit multiple beams identical to the multiple receiving beams, using the radiating elements  of the same array antenna. 
 Any use is subject to the Terms of Use as given at the website. Airborne MTI.  AIRBORNE MTI  3.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 where Rr = E{r r'}. The desired signal, d, can be expressed in terms of s, the signal  vector of a target located in the main beam, and b, the unadapted beam weight vector:  d = b' s. 
 Afirst-order correction for residual nonlinearity will result ifthe last two i-fstages ofthe two channels areidentical inevery respect. Gain adjustments should bemade inlow-level stages toavoid the introduction ofnonlinearity. Awider range ofadjustment will be required inthedelayed channel because ofpossible variations indelay-line attenuation. 
 pp. JO-J4, 1960.  109. 
 Koch, “On Bayesian MHT for well separated targets in densely cluttered environment,” in  Proc. IEEE International Radar Conference , 1995, pp. 323–328. 
 ARRAY  IMAGING  AND OVER 
 15.42  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15  88. H. Goldstein, “Frequency dependence of the properties of sea echo,” Phys. 
 12.8. The combined response curve ofthe two stages will bethe product ofthe responses ofthe individual stages and isshown bythedashed line, 1H.Wallman, RLReport A-o.524, Feb. 23,1944.. 
 P. Plant, “A stochastic, multiscale model of microwave backscatter from the ocean,”   J. Geophys. 
 SUNSET IONOSPHERE 4HESE MODELS FIND IMPORTANT APPLICATIONS TO THE ANALYSIS AND INTERPRETATION OF DOPPLER 
 It has also proven to be one of the most reliable  radar systems. Automatic detection and tracking equipments (also called plot extractors)  are commercially available for use with such radars for the purpose of collision avoi-  dance. Shore-based radar of moderately high resolution is also used for the surveillance of  liarbors as an aid to navigation. 
 LAYER TRANSMIT TIME  AND THE COLLECTOR CAPACITANCE 
 AES-9, pp. 7 14-724, September, 1973.  20. 
 ANCE WILL PRESENT AN UNDESIRABLE LOAD TO THE PRECEDING AMPLIFIER STAGE SUPPLYING THE 2& DRIVE POWER 4HIS MAY VERY WELL SEND THE PREVIOUS STAGE INTO UNWANTED OSCIL 
 25 of "Antenna Engineering Handbook," H. Jasik, (ed.),  McGraw-Hill Rook Company. New York. 
 In some cases tubes have been made in which these modes are fully suppressed, whereas in poorly designed tubes other modes may also ap- pear, such as band-edge oscillations, harmonic oscillations, etc. Usable Dynamic Range. Dynamic range and linearity may be of importance for pulse shaping, as discussed in Sec. 
 It is appropriate, therefore, to examine the erficiency of non matched filters compared  with the ideal matched filter. The measure of efficiency is taken as the peak signal-to-noise  ratio from the nonmatched filter divided by the peak signal-to-noise ratio (2£/ N 0) from the  matched filter. Figure 10.2 plots the efficiency for a single-tuned (RLC) resonant filter and a  rectangular-shaped filter of half-power bandwidth B, when the input is a rectangular pulse of  width r. 
 The smaller the apparent radar cross section  of the target, the higher the true radial velocity must be for acceptance. The true radial  velocity versus apparent radar cross section profile is intended to accept aircraft and  missiles but reject birds. Therefore, threatening targets that have high radial veloci - ties, but very small RCS, can be instantly identified, whereas returns from birds, with  their slow radial velocities, can be censored. 
   42!#+).' 2!$!2   °Î 4HIS CHAPTER DESCRIBES THE MONOPULSE SIMULTANEOUS LOBING WITH  EITHER PHASE COM 
 If the array  antenna employs nonreciprocal phase shifters, the complementary phase distribution needed  for reception is set just after the transmission of the pulse. While the system is being set for the  next transmission, the data received from the last transmission can be loaded into buITer  storage for transrer to the radar control computer. Thus, during the Nth sequence of dwell  executions, the returns from the (N -I )st sequence are processed and commands are gen­ erated for the {N + I )st sequence. 
 The delay of the pulsed echo also provides an instantaneous measurement of range. Chapters 15 to 17 relate to discrimination of desired targets from interference on the basis of velocity or the change in phase from one pulse to the next; the . ECHOES FROM DUPLEXER STCATTENTIONCONTROL AGCRF AMPLIFIER MIXER IF AMPLIFIER IF FILTER IF LIMITER SYNCHRONOUS DETECTOR ANALOG TO DIGITAL CONVERTER DOPPLER FILTER OR FILTERSSTALO COHO APC 90° ANALOG RECEIVER DIGITAL SIGNAL PROCESSOR DECODER LOG DETECTORPHASEDETECTOR LOG POWER COMBINER CLUTTER MAP CFARCELL-AVERAGINGCFAR INTEGRATORPHASE DETECTOR DECODER RMSCOMBINER INTEGRATOR CPACSDECODER DETECTEDTARGET DATA TOPROCESSOR DETECTION DECISIONS TO DISPLAY AND DATA PROCESSOR FIG. 
 D" COM 
 The radar return integral from Eq. (12.1) is a convolution integral; the figure shows the convolution of the beam pattern with the a° curve. Clearly the average at the vertical is lower than it should be to indicate properly the variation of a° near the vertical. 
 Also, a constant noise level as a  function of range at the receiver output is desirable in order to maintain a constant false  alarm rate. Noise injection after the STC attenuator is used to overcome this problem.  A noise source and attenuator are often employed at IF to inject additional noise to  compensate for the reduced noise after the STC attenuator. 
 A. Lane, R. W. 
 McGraw­ Hill Rook Company. New York. 1970. 
 2 - 1,000  8  4 -Peok due  to leading  2 . edge cl  Wtng \ I  100 8. ."-I ,, I  1 ·- I  " 0 'o I \ I  2  10' e\  5 \ \  4 \ \ I  \ I  \ I  V  ·- 2  10  8  6  4  2 -..... 
 Usually at the beginning of a new mode, the  end of each scan bar, or once per second, the calibrate and self-test subprogram is  invoked by the operational flight program (OFP) executive. A sequence of subroutines  is executed that measures phase and gain unbalance between channels using a signal  injected on the antenna. This is usually done over a range of input amplitudes, frequen - cies, and AGC settings because of the nonlinear characteristics of most RF front ends. 
 9.Sanders, W.K.:Post-war Developments inContinuous-wave andFrequency-modulated Radar,IRE Trans.,vol.ANE-8,pp.7-19,March,1961. 10.Saunders, W.K.:Control ofSurface Currents bytheUseofChannels, IRETrans.,vol.AP-4, pp.85-87,January, 1956. 11.Agar,W.O.,andM.Morgan: Isolation ofSeparate Transmitter andReceiver AerialsforContinuous WaveRadars,Marconi Review,vol.26,pp.25-34,1stqtr.,1963. 
 4.13 are f1 f0 f2 2f0f1 + f2 Target? Range (nmi) 18 21 24 42 42 Yes 10 18 21 35 42 53 No 18 29 35 58 53 No 23 29 35 58 58 Yes 20 ch04.indd   35 12/20/07   4:53:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 ALARM RATE )N THE ENSUING DISCUSSION  THE DESIGN PRINCIPLES  DRIVEN BY THE REQUIREMENTS FORCED BY THE THREAT  ARE MAINLY ADDRESSED . 
 RETARDANT PAINT IS USUALLY APPLIED TO PYRAMIDAL ABSORBERS TO SATISFY SAFETY REQUIREMENTS  BUT AT HIGH FREQUENCIES  THE PAINT TENDS TO DEGRADE THE PERFORMANCE OF THE MATERIAL .EVERTHELESS  PYRAMIDAL ABSORBERS OF SUFFICIENT DEPTH CONSISTENTLY TURN IN PERFORMANCES BETTER THAN LESS THAN   
 Pause for a moment to think what you do when you Shout against a hillside and try to get an echo, If you keep. up 2 sustained yell you cannot hear the echo, but ‘B90 wake a series of short claps or staccato shouts t .  . 
 Yadin: Distributed Airborne Array Concepts, IEEE Trans., vol. AES-18, pp. 219-226, 1982. 
 Zero response occurs only when the blind speeds of each prf  coincide. In the example of Fig. 4.16, the blind speeds are coincident for 4/Ti = SIT2. 
    7 , 3TUTZMAN AND ' ! 4HIELE   !NTENNA 4HEORY AND $ESIGN  #HAPTER   .EW 9ORK *OHN 7ILEY  AND 3ONS     # - +NOP  h/N THE FRONT TO BACK RATIO OF A PARABOLIC DISH ANTENNA v  )%%% 4RANS !NTENNAS  0ROPAG  VOL   PP n  *ANUARY    7 6 4 2USCH  h3CATTERING FROM A HYPERBOLOIDAL REFLECTOR IN A CASSEGRAIN FEED SYSTEM v  )%%%  4RANS  VOL !0 
 o 
 Itispossible tooperate apulser Withf, <l/(r a and still obtain substantially thesame voltage step-up, but thenetwork voltage atthetime offiring islessthan atsome previous time inthecharg- ing cycle. Because ofthe undue stresses that are thus placed onthe insulation, aswell asthe rapid increase inreactor losses, itiscommon practice touse, forthis case, a“hold-off” or“charging” diode inseries between the inductance and the network, toprevent the flow ofreverse current. Ifana-csupply issubstituted forthed-cenergy source, theresulting pulser isinflexible inpulse rate and pulse length, but hasthegreat advan- tage ofextreme simplicity. 
 Although nlonopulse tracking radars are capable of  excellent accuracy, when monopulse is applied to a 2D surveillar~ce radar the angle accuracy is  usually poor. One reason is the broad elevation beamwidths. (The rms error of an angle  measurement is proportional to the beamwidth.) Another limitation is the effect of multipath  due to reflection from the earth's surface. 
 Appl. Geogr. 2015 ,58, 65–83. 
 MENCED  THAN FOR THE DRY NIGHTTIME SNOW (ENCE  DIFFERENT MODELS MUST BE USED FOR DAY AND NIGHT COMPARE THE  DAY  AND  NIGHT  MEASUREMENTS SHOWN IN &IGURE  4HE DIFFER 
 CESSING  DIGITAL PULSE COMPRESSION  AND COHERENT INTEGRATION AND AUXILIARY PROCESSING AIMED AT SUPPORTING THE 34!0 SAMPLE SELECTION PROCESS 4HE !.!09 
 Rept. RM-1008, Dec. 17,  1952, Santa Monica, Calif. 
 4ARGET 4 /4  /BVIOUSLY  MOST RADARS DO NOT CONTAIN ALL OF THIS VARIATION  BUT MODES EXIST IN MANY  FIGHTER AIRCRAFT  WHICH REPRESENT A GOOD FRACTION OF THE PARAMETER RANGE -OST FIGHTER RADARS ARE FREQUENCY AGILE SINCE THEY WILL BE OPERATED IN CLOSE PROXIMITY TO SIMILAR OR IDENTICAL SYSTEMS 4HE FREQUENCY USUALLY CHANGES IN A CAREFULLY CONTROLLED  COMPLETELY COHERENT MANNER DURING A #0)  4HIS CAN BE A WEAKNESS FOR CERTAIN KINDS OF JAMMING  SINCE THE PHASE AND FREQUENCY OF THE NEXT PULSE IS PREDICTABLE 3OMETIMES TO COUNTER 
 Measurements are independent if the frequency is changed by an amount36  C  !!.:fc = "ii5 (5.3)  where c = velocity of propagation and D = target depth. The glint error can be reduced by  averaging the independent measurements obtained with frequency agility. (The depth D as  seen by the radar might be less than the geometrical measurement of target depth if the  extremities of the target result in small backscatter.)  The improvement I in the tracking accuracy when the frequency is changed pulse-to-pulse  is approximately37  (5.4)  where B fa= the frequency agility bandwidth, D = target depth, c = velocity of propagation,  B11 = glint bandwidth, and J,. 
 If one radar has one- tenth the ROU of the other in this dimension, then the more accurate radar in this dimension  will dominate and essentially determine the result. At least in steady state, it is relatively  easy to produce this dominance by any of the fusion methods. Of more interest is the case  where the radars are comparable in terms of accuracy and update rate, producing compa - rable ROUs. 
 Thesefiltersmightbe"optimum" inthattheysatisfythespecified criterion, butthecriterion mightnotbethebestforsatisfying MTIrequirements. (Optimum isnota synonym fo.rbest;itmeansthebestunderthegivensetofassumptions.) Maximizing the signal-to-clutter ratiooveralldoppler frequencies, whichleadstothebinomial weightsand sin"1tjdTfilters,isnotnecessarily apertinent criterion fordesignofanMTIfiltersincethis criterion isindependent ofthetargetsignalcharacteristics.3-5ItwouldseemthattheMTI filtershouldbeshapedtorejecttheclutteratd-candaroundtheprfanditsharmonics, but haveaflatresponse overtheregionwherenoclutterisexpected. Thatis,itwouldbedesirable tohavethefreedom toshapethefilterresponse, justaswithanyconventional filter. 
 Coleman: Virtual Source Luneburg Lenses, Symposirrrn or1  ;\ticr.o\cc~r.e Oi~tics, McGill University, Montreal, AFCRC-TR-59-I18(1), ASTIA Document 21 1499,  pp. 18-21. April, 1959. 
 Amplitude, phase and, to a limited extent, co u- pling can be corrected during the processing. The restrictions that us ually apply to phased arrays   will be relaxed, because the coherence and phase relatio nships will be during post- processing and  calibration. These receive systems will have a lower noise figure than standard phased array r e- ceivers, because the phase shifters are eliminated. 
 13. Y . Sharay and U. 
 )Furthermore, itis often possible touseone orboth oftheapproximations sino=oand cos e=1.Inany case inwhich asweep component isunipolar, theclamps ofFig. 13.46 canbereduced tounstitched d-crestorers, and theswitched clamps ofFig. 13.51 can become single-sided, though still being switched. 
 BAND RADARS HAVE BEEN CONSIDERED TO SOME DEGREE BUT THE MORE SEVERE ATTENUATION THAT CAN OCCUR IN VERY HEAVY RAIN WILL LIMIT PERFORMANCE UNLESS THE RADAR IS LOCATED VERY NEAR TO THE AIRPORT RUNWAYS )N THE MID 
  
 The delay circuits inthe synchronizer may beany ofthe varieties described inSees. 13.7 and 13.12, the most precise and trouble-free results being obtained bytheuse ofcircuits similar tobut not sorefined asthecircuit shown inFig. 13.36. 
 Prop ., vol. AP-30, pp. 837–845,  1982. 
 This is the  efficiency of interest to the tube designer. The system engineer, however, is more concerned  with the overall transmitter efficiency, which is the ratio of the RF power available from the  transmitter to the total power needed to operate the transmitter. If, for example, the RF  efficiency of a microwave tube were 40 to 50 percent, the transmitter efficiency might be 20 to  25 percent. 
 0  0 #' &)"$& 
 However, the use of E1 in the equation does have the advantage of avoiding the problems of defining P1 and T, and it is especially useful when complicated waveforms are transmitted. If coherent integration for a fixed integration time is assumed, the equation can also be written with the transmitted average power in the numerator. For simple pulse radars, the average power is the product of pulse power, pulse length, and pulse repetition frequency. 
   PP n  *ULY   ' 6 4RUNK AND " ( #ANTRELL  h!NGULAR ACCURACY OF A SCANNING RADAR EMPLOYING A  
 ‡  “Fully coherent” is described under rule 3. ch02.indd   92 12/20/07   1:52:13 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 ch18.indd   69 12/19/07   5:15:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 However, the missile is still closing on this target at 1500 ft/s; so it is in the approach part of the spectrum, above feedthrough, even though it is an outbound, or receding, target. (Note that if the outbound target were faster than the missile, its doppler would be below feedthrough, but of course the missile would never catch up with it. Thus, it is a FIG. 
 AUTHOR OF THIS CHAPTER  FOR #HAPTER   h2EFLECTOR !NTENNAS v IN THE SECOND   EDITION OF THIS HANDBOOK  7E ARE GRATEFUL FOR THEIR CONTRIBUTIONS AND PORTIONS OF  THE SECOND EDITION CHAPTER HAVE BEEN RETAINED 0ORTIONS OF THE MATERIAL IN THE h2ADOMEv SUBSECTION WERE ADAPTED FROM  #HAPTER  h2ADOMES v IN THE FIRST   EDITION OF THIS HANDBOOK  WHICH WAS  AUTHORED BY 6INCENT * $I#AUDO , 
 , AMS, Boston, 1970, pp. 139–144. 153. 
 Other factors limiting large powers are the difficulty of operating with high voltages, of  dissipating hcat in the collector, and of obtaining sufficient cathode emissio~l citrrcnt.  Examples. Klystrons have seen wide application in radar. 
 Figure 8.8 shows a sketch of a SAW pulse compression device with dispersive  input and output transducers. As the energy in a SAW device is concentrated in its sur - face wave, the SAW approach is much more efficient than bulk-wave devices, where  the wave travels through the crystal. The propagation velocity of the surface wave is  in the range of 1500 to 4000 m/s, depending on the crystal material, and allows a large  delay in a compact device. 
 Incidence ranges from 10 ° to 60 °, including the extended modes.  There are seven standard modes, each having its own elevation beam; these modes  have nominally 25 m by 28 m (4 looks), 100-km swaths. The NEq s  0 is –20 dB or  better and mode-dependent. 
 PGIT-3, pp. 26-51, March,  1954.  33. 
 Frequency channels are typically selected  or communicated to the radar immediately before launch. If the data link frequency is  well below the radar band, usually a small number of radiators at that lower frequency  are imbedded in the radar aperture. If the frequency is close enough to the radar band,  the radar aperture or a segment of the aperture is used. 
 Figure 8.8shows this effect. Itisclear that ifwe consider interrogation that begins when the separation isfirst large and then decreases, thebeaconFIG.S.7.—Schematic logarithmic polar diagram oftheantenna pattern ofa microwave radar. The triggering ofa beacon occurs when theenergy radiated inagiven direction isinexcess ofsome necessary minimum amount. 
 FIER 4HE OTHER MAJOR ADVANTAGE IS THAT SEARCH VOLUME CAN BE CHANGED DYNAMICALLY TO FIT THE INSTANT TACTICAL SITUATION  AS SUGGESTED IN &IGURE   4HE FEED NETWORK IS MUNDANE BUT CRITICALLY IMPORTANT )N SINGLE TUBE TRANSMIT 
 15-20. January, 1975.  49. 
 ALTITUDE TARGETS v IN )%%%  )NTERNATIONAL 2ADAR #ONFERENCE  -AY  PP n  7 "ATH  h4RADEOFFS IN RADAR NETWORKING v IN  0ROC )%% 2!$!2     PP n  * 2 -OORE AND 7 $ "LAIR  h0RACTICAL ASPECTS OF MULTISENSOR TRACKING v IN  -ULTITARGET 
 OUT 
 Radar antennas operate in· the Fraunhofer  region.  The" boundary" RF between Fresnel and Fraunhofer regions is usually taken to be either  RF= D2/). or the distance RF= 2D2/A, where D is the size of the aperture and )._ is the  wavelength, D and). 
 ('WANDFRI'<)lIFNC¥-MODULATED RADAR87 wltl'leH.,.,.,range(altitudc). III c=vclocityofrroragation. m/s !1f=frcqucncy cxcursion. 
 COVERED LEVEL TREELESS TERRAIN   SO SOME PULSES MAY BE INTEGRATED COHERENTLY TO IMPROVE SIGNAL 
 A. Mayer:" Radar Target Detection," Academic Press, New York, 1973.  12. 
 This is called  skin tracking to differentiate  it from beacon tracking, where a beacon or a transponder transmits its signal to the  radar and usually provides a stronger point-source signal. Because most targets, such  as aircraft, are complex in shape, the total echo signal is composed of the vector sum   of a group of superimposed echo signals from the individual parts of the target, such as  the engines, propellers, fuselage, and wing edges. The motions of a target with respect  to the radar causes the total echo signal to change with time, resulting in random  fluctuations in the radar measurements of the parameters of the target. 
 When extensive vertical coverage is re- quired, the aircraft's planform and vertical stabilizer distort and shadow the an- tenna pattern. Analysis of tactical requirements may show that only a limited coverage sector is required. However, this sector usually has to be capable of being positioned over the full 360° relative to the aircraft's heading because of the requirements for coverage while reversing course, large crab angles when high winds are encountered, need to position ground track in relation to wind, nontypical operating situations, and operational requirements for coverage while proceeding to and from the station. 
 Kuck, “Latching ferrite phase shifter for phased arrays,”  Microwave J ., pp. 97–102, March 1967. 93. 
 R. Seu, D. Biccari, R. 
 117–121, 2006. 14. E. 
 Stover, “On binary sequences,” Proc. Am. Math. 
 Mavroides. W. Ci.: Weather Tracking with the AFCL Experimental 3-D Radar, AFCRL-70-0006, Air  Force Cambridge Research Luhorarories. 
 Griffiths and N. R. W. 
 Althoi~gh such lerlstls  Ilad interesting properties, they were only of academic interest since optical materials with the  required variation of index of refraction were not practical. However, at microwave freqilen-  cies it is possible to control the index of refraction of materials (q is the square root of the  dielectric constant 0, and lenses with a noni~niform index of refraction art: practical.  One of the most important of the variable-index-of-refraction lenses in the field of radar is  that due to Luneburg.'' The Luneburg lens is spherically symmetric and has the property that  a plane wave incident on the sphere is focused to a point on the surface at the diametrically  opposite side. 
 Consider the output of a typical radar receiver as a function of time (Fig. 2.1). This  might represent one sweep of the video output displayed on an A-scope. 
 I. Skolnik, Introduction to Radar Systems , 3rd Ed., New York: McGraw-Hill, 2001, p. 772. 
 TIME 
 T      S   4HE PULSE 
 Another potential safety hazaid in working with high power is the generation of X rays  when high voltages are used to opera& RF power tubes. Tubes must be properly shielded with  lead, and X-ray safety badges worn by operating personnel to warn of excessive dosage. >,  REFERENCES  I. 
 The silicon bipolar transistor technology is very mature, and, with the continuing advances in device processing, packaging, and circuit design techniques, manufacturers should be able to continue demonstrating increased levels of power output, bandwidth, and reliability for these transistors. In addition, as a relative figure of merit, the cost per watt of device output power has been decreasing as a result of improvements in processing yields and as a result of increased automated or semiautomated assembly techniques. Microwave power transistors can be considered complex hybrid circuits and are generally single-chip or multichip devices. 
 The result is a wave­ form whose average shape is given by the double con­ volution of the system's point target response, the  ocean-surface height distribution, and the two-way an­ tenna pattern. The angles involved are much steeper than  Fig. 1 suggests (less than 1 degree); thus, the effects of  earth curvature and changing geometry have been  ignored. 
 Inc.. Dedharn. Mass.. 
 Unfortunately ithas been impossible todesign magnetrons that donot show multiple frequencies under some conditions and this phenomenon remains asone ofthemost troublesome encountered inpulsed magnetron operation. F1~. 10.9.—Rising-sun magnetron with waveguide output andradial cathode leads. 
 2.7 corresponding to the desired value of detection  probability P,, and false-alarm probability PI, .  2. From Fig. 
 BEAM CLUTTER ARE BLANKED TO MINIMIZE FALSE ALARMS ON MAIN 
 HORN MONOPULSE FEED v  )2% )NT #ONV 2EC    PART   -ARCH   PP n  0 7 (ANNAN AND 0 ! ,OTH  h! MONOPULSE ANTENNA HAVING INDEPENDENT OPTIMIZATION OF THE SUM  AND DIFFERENCE MODES v )2% )NT #ONV 2EC  PART   -ARCH   PP n.   2%&,%#4/2 !.4%..!3   £Ó°{Î  " 3AKA AND % 9AZGAN  h0ATTERN OPTIMIZATION OF A REFLECTOR ANTENNA WITH PLANAR 
 Rudnick, P.: The Detection of Weak Signals by Correlation Methods, J. Appl. Phys., vol. 
 These are ( 1) the maximum amount of power the receiver  input circuitry can withstand before it is physically damaged or its sensitivity reduced  (burnout) and (2) the amount of transmitter noise due to hum, microphonics, stray pick-up,  and instability which enters the receiver from the transmitter. The additional noise introduced  by the transmitter reduces the receiver sensitivity. Except where the CW radar operates with  relatively low transmitter power and insensitive receivers, additional isolation is usually  required hctwc·cn the transmitter and the receiver if the sensitivity is not to be degraded either  by burnout or by excessive noise. 
 Monopulse tracking is necessary to obtain angle data on each pulse to  maintain adequate data rates when sharing pulses and power among several targets. A  detailed discussion of electronic scan phased arrays is given in Chapter 13; however,  some characteristics of the arrays require special consideration for the angle tracking  performance of tracking radars using monopulse phased array antennas. Optical-feed Monopulse Electronic Scan Arrays. 
 This results in the lower of the two  peaks of the symmetrical A/C ratio being placed in the direction of the bisector of the target  and image. Under this condition, the values of A/C in the direction of the target and its image  are equal. ?'he estimate of target elevation is unaffected by the phase and amplitude of the  image. 
 C.: Optical Scanners, chap. 3 of" Microwave Scanning Antennas, vol. I," R. 
 Prin- cipally, this detection occurs in the summer months. The backscattering mecha- nism may be due to index-of-refraction inhomogeneities caused by turbulence in the lower layers and/or by insects. Wilson and Schreiber have found that about 90 percent of the thunderstorms that occur in the Front Range of the Rockies in the summertime develop over such boundaries. 
 The resulting elevation-angle data is independent of the manner in which the target is illuminated by the radar and is dependent only on the squinted receiving-antenna patterns. In analyzing the elevation-angle errors due to ground reflections, we shall con- sider the case where the boresight crossover of a pair of squinted receiving beams (A and B) is oriented exactly on the target at elevation angle 6 (a condition of zero error in the absence of ground reflections). See Fig. 
 9.  pp. 47 56. 
 Ludington: A Charge Transfer Device MTI Implementation, IEEE 1975  Irrtc~rtratiorral Rndur C'oi!firetrcr Record, pp. 107-1 10, IEEE Publication 75 CHO 938-1 AES.  36. 
 Mohr: Polarization Insensitive Phase Shifter for Use in Phased Array  Antennas. hfic.ro\c*c~r.e J., vol. 12, pp. 
 In Proceedings of the 2016 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Beijing, China, 10–15 July 2016; pp. 5670–5673. 7. 
 The drawback of the grid-controlled vacuum tube is that transit-time effects  limit its application at microwave frequencies, but variants of grid-controlled vacuum  tubes have been successfully used up to about 1000 MHz. The barrier of transit time effects was overcome with the invention of the micro - wave cavity magnetron  early in World War II in 1940 by the United Kingdom (UK).  The introduction of the magnetron allowed high-power radar to be successfully  developed for use at the higher frequencies where smaller size antennas could be  used. 
 2014 ,52, 1856–1868. [ CrossRef ] 18. Chen, J.; Quegan, S. 
 TEMPORAL CLUTTER COVARIANCE MATRIX THE DATA 
 Another important consideration'in the selection of an antenna element and the design of  an array, is the mutual coupling between the radiating elements. When the field intensity  pattern of an array antenna was .considered previously [Eq. (8.3)) it was assumed that the  elemental radiators were independent of one another. 
 The sharp edges of the building are slightly misregistered in the images and these registration errors are false positives in the 2CMV image. In this work, we introduce a new framework of image processing methods for the efﬁcient generation of 2CMV products toward extraction of advanced geospatial intelligence. Before false positive and object detection algorithms are performed, speckle and smoothing ﬁlters are used to mitigate the effects of speckle noise. 
 L. J. Cutrona, “Synthetic aperture radar,” in M. 
 W. Howells, and C. Kovarik, “Multiple Intermediate Frequency Side-Lobe  Canceler,” U.S. 
 With grid size AJC, the artificially induced grating lobe will ap- pear at the angle found from sin 0 = XlAx. Frequently, the user of such compu- tational tools will trade off grid density in the orthogonal plane to enhance com- putation accuracy in the plane of interest. Typically, the computer time-consuming operations in this type of pattern computation are trigonometric functions, sines and cosines, and square roots used in length and thus phase calculations. 
 From Eq. (2.36) together with Eq. (2.31) and the definition of input temperature, it is deduced that the input noise temperature of a receiving transmission line of thermal temperature Ttr and loss factor Lr is . 
 Oppenheim and R. W. Schafer, Digital Signal Processing , 2nd Ed., Englewood Cliffs, NJ:  Prentice-Hall, 1989. 
 TRIBUTED 4HE "ARKER CODE IS THE ONLY UNIFORM PHASE CODE THAT REACHES THIS LEVEL  !LL THE KNOWN BINARY "ARKER CODES ARE LISTED IN 4ABLE  /NLY BINARY "ARKER CODES OF LENGTHS             AND  HAVE BEEN FOUND n ! PULSE COMPRESSION RADAR USING "ARKER CODES WOULD BE LIMITED TO A MAXIMUM  TIME 
 248INTRODUCTION TORADAR SYSTEMS cannotbeusedduringthisperiodofambiguity, calledthedeadtime.Inonemodelofthe organ-pipe scanner,J6elements werefed,threeatatime.121lThedeadtimeforthismodelis equivalent torotation pasttwoofthe36elements; consequently itwasinoperative about6 percentofthetime. InFig.7.17thefeedsareshownonastraight line,butintheparabolic torustheywould lieonthearcofacircle. Themanyfeedhornsplusallthetransmission linesoftheorgan-pipe scanner resultina relatively largestructure withsignificant aperture blocking. 
 VII. The targets were modelled as Swerling Case 1 (a slow fading target with a radar cross-section having an exponential distribution) and a nominal probability of false alarm at the display of 10−4was assumed. If the minimum size of a focussed spot on the PPI was 0.5 mm, then this would achieve about 10 false alarms per scan on a 5 inch diameter PPI. 
 413 424, Apr. I.  1947. 
 To  detect the doppler frequency shift for MTI processing, the phase cannot change in a  random manner at the receiver from pulse to pulse. This limitation is overcome by  taking a sample of the random phase of each transmitted pulse and using it to reset  the phase of the local oscillator in the receiver to match the phase of the transmitted  signal. This is sometimes called coherent on receive . 
 Walton and J. D. Young, “The Ohio State University compact radar cross section measurement  range,” IEEE Trans. 
 BANDWIDTH )& AMPLIFIER 4HE WIDEBAND AMPLIFIER ALLOWS A RAPID RECOVERY TIME FROM THE EFFECTS OF THE SWEPT JAMMER  AND THE LIMITER CUTS THE JAMMING SIGNAL 4HE NARROWBAND TARGET SIGNAL  AFTER TRANSIT THROUGH THE WIDEBAND AMPLIFIER AND THE LIMITER WITHOUT REMARKABLE DEGRADATION  IS INTEGRATED BY  THE NARROWBAND FILTER MATCHED TO THE SIGNAL 4HE WORD  &IX IN THE $ICKE 
 REFLECTOR ANTENNAS  12.396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 Deployable space-based reflectors have also been developed by the Harris Corpo- ration for various space-based communications applications. See www.harris.com for  more details. Because most reflector designs have at best limited electronic scan capability, a  gimbal is typically needed to extend the (mechanical) FOV for the radar. 
 MITTERS  THE 0"2 HAS NO CONTROL OVER THEIR TRANSMISSION OR WAVEFORM PROPERTIES  SPECIFICALLY THE TRANSMISSION SCHEDULE  EFFECTIVE RADIATED POWER  SPATIAL COVERAGE  MODULATION TYPE  MODULATION CONTENT  AND RESULTING AUTOCORRELATION FUNCTION  AS OUT 
 An idealized  correction signal Ec is applied, leading the received signal by 90 ° and lagging the next  received signal by 90 °. For exact compensation, the following relation would hold:  E EV T cx p= = ∑122tan ( )tansinη θπ θ λ  (3.8) This assumes a two-lobe antenna pattern similar to that in a monopulse tracking  radar. Two receivers are used, one supplying a sum signal, Σ(q ), and the other a  difference signal, ∆(q ). 
 138–144, 1980. 135. J. 
 38Attack Approach • A network of radars are arranged to  provide continuous coverage of a  ground target. • Conventional aircraft cannot penetr ate the radar network without being  detected. GROUND TARGET ATTACK  APPROACHFORWARD EDGE OF   BATTLE AREA (FEBA)Rmax RADAR DETECTION RANGE, R max. 
 Its wavelength is10.7 cm, and itemploys anantenna reflector 8ftindiam- eter. The waveguide feed used isalittle offtheaxis oftheparaboloid, sothat thebeam, whose width is3°,isoffaxis by1°. The feed isrotated toproduce the conical scan. 
 (In the above, the  relations 1*74 = L, = RA/I) were employed.)  Range resolution. In niappitig or itliaging. it is usually desired to have the range resolution  eqilal to the along-track, or cross-range resolution. 
 The echo fluctuations not related to antenna beam position cause false target angle- tracking errors. FIGURE   9.13  Conical-scan tracking ch09.indd   16 12/15/07   6:07:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 TARGET 
 The pulse transformer will beconsidered inthefollowing sec- tion, since itisapplicable toboth types ofpulsers. Ingeneral, itcan be said that the effect ofboth the switch and the pulse transformer isto decrease therate ofrise ofvoltage attheload from that which would be produced bythe network alone. The switch usually introduces an appreciable resistance during itsionizing time, and thepulse transformer introduces anadditional inductance inseries with theload. 
 Radar Conf. Rec., pp. 775-781, Nov. 
 The computational complexity of the different methods. 5. Results 5.1. 
 However, in prac­ tice it is seldom required that a radar generate more than a few simultaneous beams (perhaps  no more than a dozen), since the complexity of the array radar increases with increasing  number of beams.  Although the array has the potential for radiating large power, it is seldom that an array is  required to radiate more power than can be radiated by other antenna types or to utilize a  total power which cannot possibly be generated by current high-power microwave tube tech­ nology that feeds a single transmission line.  Conventional microwave antenn.as cannot generate radiation patterns with sidelobes as  low as can be obtaineq by an array antenna, especially a nonscanning array. 
 SIGHT COMPONENT OF TARGET VELOCITY IN UNITS OF RADAR PLATFORM VELOCITY  SO THE MAIN 
 Naturally,  each type of error must be anticipated, and one must allow a budget for failed ele - ments, amplitude errors, and phase errors. For a number of independent sidelobes, the probability that n sidelobes can be kept  below a given level RT is equal to the product of the probabilities that each sidelobe  can be held below this level:  P n R P R RT i T in [ ] [ ( ) ] sidelobes< = < =∏q 1   Ri i ( )q q =sidelobelevel at  Assuming the same sidelobe requirement at each qi,  P [n sidelobes < RT] = {1 − P [one sidelobe > RT]}n  and for P [one sidelobe > RT]  1,  P [n sidelobes < RT] ≅ 1 − n P [one sidelobe > RT]  A simple example will illustrate the process. If it is necessary to keep all 100 sidelobes  in a sector below −40 dB with a probability of 0.9, determine the required probability on  any one given sidelobe:  0.9 = P [100 sidelobes < 40 dB]  Then  0.9 = 1 − 100 P [one given sidelobe > 40 dB]   0.001 = P [one given sidelobe > 40 dB]   0.999 = P [one given sidelobe < 40 dB]  That is, to keep all 100 sidelobes below −40 dB with a probability of 0.9, it is necessary  to keep any given sidelobe below −40 dB with a probability of 0.999. 
 The beams are  time shared by a single channel which is switched through the four-beam sequence every . CW AND FREQUENCY-MODULATED RADAR 95  250 ms. A phase-monopulse technique is used to reduce the terrain bias effect.68 The unit  weighs 44 pounds including radome, and requires 165 VA of power. 
 PULSE hMATCHEDv FILTER PROVIDES OPTIMUM RADAR DETECTION PERFORMANCE WHEN USED IN A WHITE 
 Jr., and R. C. Dodson: Parasitic Spiral Arrays, IRE Intern. 
 We also have advantage in f1-score. (4) Our method also has good generalization ability. Our paper has presented the application 308. 
 The largest relativ e Doppler frequency changes result from transverse objects.   The Doppler history for transverse objects is shown next to each other in Figure 9.5, as they result from a “fly -by”, for successive resolution regions.  The lines begin, where the scatterer  is seen first by the Radar antenna and end, when it leaves the antenna main beam. 
 −1.03 V and H 0 1–6 (1976)  6.4   . −0.73 V and H 0 6–17  0.9   .   0.10 V and H 10 1–6 (1975)  −9.1   . 
 Figure 1. SAR Data acquisition geometry. In several cases, due to imprecise knowledge of the satellite or aerial vehicle acquisition geometry or due to the presence of motion in the scene (ships, cars, etc.) a bad quality of the image is obtained (defocusing); many authors addressed the problem of a post processing procedure able to exploit the residual correlation present in data to perform accurate focusing of the image. 
 SWITCH MODULATOR  THE SWITCH HAS TO BE TURNED OFF AS WELL AS TURNED ON  /RIGINALLY  THE SWITCH WAS A VACUUM TUBE AND THE MODULATOR WAS CALLED A HARD 
 STATE DEVICES OR MODULES ARE COMBINED IN ONE OF THREE FUNDAMENTAL CONFIGURATIONS TO GENERATE THE REQUIRED TRANSMITTER POWER LEVELS &IGURE  SHOWS THAT THIS MAY INVOLVE EITHER THE COMBINATION OF AMPLIFIER OUTPUTS TO A SINGLE PORT TO FEED A MECHANICALLY ROTATING ANTENNA OR SOME COMBINATION OF ELECTRONIC PHASE STEERING AND AMPLIFICATION DISTRIB 
 Practical extreme values of scanning are therefore in the region of 60  to 70 °. A minimum of three planar array apertures is then necessary for hemispherical  coverage. The antennas may be positioned as shown in Figure 13.1, permitting a view  that is unimpeded by the central superstructure. 
 but some variation can be tolerated so lottg as it is not  sufficier~t to produce uneven illunti~iation of tlte cathode-ray tube display or degradation of the  MTI.  1. Silver. 
 PLEST ADAPTIVE DETECTOR  SHOWN IN &IGURE   IS THE CELL 
 LATION AS WELL AS JAMMER CANCELLATION WITH SUITABLE HARDWARE AND SOFTWARE   n &)'52%  ! 
 If not, multiple steps of selection, crossover, and mutation should be carried out to generate a new population of individuals, after which the ﬁtness function value will be calculated again. If it is satisﬁed, the generated individual genes will be selected as the ﬁnal estimated parameter. (3) As mentioned in [ 34], the simplex method can improve the precision of the results generated by the genetic algorithm; thus, we introduce it into our experiment to optimize the searching results. 
 LUTION 4HEN THE PROCESSOR LOOKS FOR THE RANGE CELL WITH THE MAXIMUM ENERGY CONTENT AND COMPUTES THE 76$ ;7IGNER 
 Thecathode mustberuggedtowithstand theheatingand disintegration causedbytheback-bombardment ofelectrons. Back-bombardment increases thecathode temperature duringoperation andcausessecondary electrons tobeemilled. For thisreasontheheaterpowermaybereduced oreventurnedoffoncetheoscillations have started.Therelatively fatcathode, required fortheoretical reasons, candissipate moreheat thancanathincathode. 
 Often, distributed targets are of interest because echoes from them (called radar clutter) tend to mask the echoes from the point targets whose detection is desired (see Sec. 2.8). Echoes from rain may be regarded as clutter when they interfere with detec- tion of aircraft or other point targets, but they are themselves the signals of prime interest for weather radar. 
 TIONS AT THIS GRAZING ANGLE FOR WINDS OF ABOUT  KT &URTHER LABORATORY AND THEORETI 
 Clarricoates, P. J.B., and G. T. 
 The frequency cicpendence for  concrete, asphalt, and cinder and gravel roads varies approximately as the square of the  freq~ency.~'  Effect of resolution. The use of a', the cross section per unit area, to describe the radar  scattering from clutter, implies that the clutter is uniform and independent of the radar-  resolution-cell area. In reality, land clutter is not uniform. 
 R. h2.. arid K. 
 21. GEOS-C Mission Plan, NASA TK-6340-001, rev. 3, NASA Wallops Flight Center, Wallops Island, Va., Dec. 
 At first glance, it might seem that  the signal-to-noise ratio required for detection is higher than that dictated by intuition, even  for a probability of detection of 0.50. One might be inclined to say that so long as the signal is  greater than noise, detection should be accomplished. Such reasoning may not be correct when  the false-alarm probability is properly taken into account. 
 ('orlsider, for example an array with spacing d = 0.6Ro and l/d = 15. This corresponds to  IU = Illo = 9. From Fig. 
 Although  these concepts had been explored many years earlier using the Velocity Indicating  Coherent Integrator (VICI)1 or the Coherent Memory Filter (CMF)2,54 to implement a  doppler filter bank, and storage tubes or magnetic drum memory to implement clut - ter maps, it was the work at the MIT Lincoln Laboratory to improve the performance  of airport surveillance radars that resulted in one of the first working examples of  what has become known as the Moving Target Detection (MTD) radar.3,4 The theory  and expected benefits of this approach were described in two reports in 1972,5 which  provided the mathematical foundation for the understanding and the practical imple - mentation of the MTD concept. The predicted subclutter visibility improvement for the ASR-7 airport surveillance  radar, when the three-pulse MTI processor was replaced by the second-generation  MTD II processor, is shown in Figure 2.6. FIGURE  2.6 Subclutter visibility comparison between three-pulse MTI and MTD II PERCENT  OF DETECTION = 50 Pfa = 1 x 10−5 ASR–7/MTD II ASR–7/MT ISCV IN dB 010203040 0 0.2 0.4 0 .6 0.8 1.0 RADIAL  VELOCITY/BLIND SPEED ch02.indd   6 12/20/07   1:42:50 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 127, p. 27, Oct. 19, 1987. 
 and maintainability (sornctimcs these last three are  called RAM); electromagrietic compatibility (EMC) requirements; restrictions on size, weight,  cost, and delivery: type of prime-power available; restrictions on warm-up time and shut-  dowti procedures; and the form in which tlie output information froin the radar isdesired. The  user (or buyct ) sl~oi~ld i~ttctnpt to liliilt llic rcqtlirctlictits to stalcnicllls of pcrforlnatice r'atlicr  than give them in ternis oCspecific radar cllaracteristics wliicli restrict the radar designer in tile  clioiccs i~vnil:~hle.  Characteristics of a long-range air-surveillance radar. 
 Transmit radiating element choice is driven primarily by the range of frequencies  to be radiated and the waveform bandwidth, but it must also take into account the  range and azimuth coverage required, the associated coverage rate, and concerns  about clutter, especially spread-doppler clutter. The vertical radiation pattern con - trols these issues. The power-handling capabilities of the antenna elements are also  a consideration. 
 SPECIFIC IMPLEMENTA 
 Each energized array ekment was driven from a separate power  amplifier. which obtained i'ts properly phased input signal from a Luneburg lens. This lens  functioned as a low-power RF analog beam~formingdevice for the spherical array. 
 (Courtesy IEE )11PD0.6 0.5 0.4 0.3 0.2 0.1 000 0100 200 300 400 500 600 R 1×103700 800 900 10000.70.80.9 FIGURE 21.9  Layout of transmission line model ( courtesy IEE )LAYER  1AIRLAYER  2LAYER  3LAYER  4LAYER  5 TABLE 21.3  Layer Characteristics for Transmission Line Model Layer Range in Meters Relative Dielectic Constant erLoss Tangent Material 0 0  1 0 Air 1 0.3  6  0.31 Lossy layer 2 0.6  1 0 Air void 3  0.85  9  0.01 Sub base 4 1 16 0.1 Wet base 5 infinite 25 0.1 Wet bedrock ch21.indd   15 12/17/07   2:51:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 
 In a typical duplexer application the transmitter peak power might be a megawatt or . 360 INTRODUCTION TO RADAR SYSTEMS  more and the maximum safe power that can be tolerated at the receiver might be less than a  watt. Therefore, the duplexer must provide, in this example, more than 60 dB of isolation  between the transmitter and receiver with only negligible loss of the desired signal. 
 Weiss: Solid-State X-Band Power Limiter, IRE Trans., vol.  MTT-9, pp. 472-480, November, 1961. 
 2 1. Fcnstcr. W.: 7'lie Applicatiori. 
 Range rate (i.e., doppler) measurements are formed with a centroid on the target’s  doppler return in the filter bank. Angle measurements can be obtained using monopulse,  sequential lobing, or conical scan, with monopulse being the prominent choice in mod - ern radars. The tracker creates windows, or groups of contiguous range-doppler cells,  around each of these measurements in order to associate detections with existing tracks. 
 5 Summary of Phase and Autocorrelation Characteristics of Frank and Lewis and  Kretschmer Polyphase Codes ch08.indd   22 12/20/07   12:50:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 
 26.Reintjes, J.F..andG.T.Coate:"Principles ofRadar." Chap.3,McGraw-Hili BookCompany, New York.1952. 27.Parker. W.N.andM.V.Hoover: GasTuhesProtectHigh-Power Transmitters, Electronics, vol.29, pp.144147,January. 
 Most high-performance radar klystrons tend to employ the  more intricate cavity structure because of the better performance it provides. Comparison of Various Linear-Beam Tube Structures . Figure 10.3 illustrates  the basic structure of the RF circuits that characterize the various types of linear- beam tubes. 
 SIVE FILMS USED TO BOND THE LAYERS TO EACH OTHER 4HESE MATERIALS ARE TOO FLIMSY OR TOO HEAVY FOR MOST MILITARY APPLICATIONS 4HE PYRAMIDAL ABSORBER USED TO SUPPRESS WALL REFLECTIONS IN INDOOR CHAMBERS  REPRESENTS A PARTICULARLY EFFECTIVE METHOD OF VARYING THE EFFECTIVE IMPEDANCE hSEENv  &)'52%    0ERFORMANCE OF *AUMANN ABSORBERS  WITH AS MANY AS FOUR SHEETS !LL FOUR OF THESE TRACES WERE  OPTIMIZED FOR MAXIMUM BANDWIDTH AT THE n D" LEVEL 4HE SHEET RESISTIVITIES MUST INCREASE FROM A LOW VALUE AT THE INNER SHEET TO A HIGH VALUE AT THE OUTER SHEET. £{°În  2!$!2 (!.$"//+  BY AN INCIDENT WAVE 4HE ABSORBER IS MADE OF FLEXIBLE  CARBON 
 SIZED AIRCRAFT      .   (& /6%2 
 TIES OF THE POLARIZED PART OF THE ECHO FROM A TARGET 7E CAN ALSO DESCRIBE THE SCATTERING USING THE -UELLER MATRIX THAT IS RELATED TO THE  3TOKES MATRIX 4HE READER IS REFERRED TO THE LITERATURE FOR FURTHER DESCRIPTIONS OF THE  -UELLER MATRIX .   '2/5.$ %#(/  £È°x£ 4HE USUAL WAY TO OBTAIN POLARIZED RESPONSES IS TO TRANSMIT ALTERNATE VERTICALLY AND  HORIZONTALLY POLARIZED PULSES 0RESUMING THERE IS ALMOST NO CHANGE IN THE TARGET DUR 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 22.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 geographically fixed. 
 BASED DUAL 
 TO 
 CONGESTED (& SPECTRUM  SO THE PRESENCE OF INTERFERENCE FROM OTHER MANMADE SOURCES IS EFFECTIVELY  DIMINISHED BY SUITABLE FREQUENCY SELECTION 7HEN JAMMING IS PRESENT  THE RADAR MAY  NEED TO OPERATE WITH MUCH HIGHER THAN USUAL LEVELS OF INTERFERENCE THAT CAN DEGRADE PERFORMANCE &OR THIS REASON  PROTECTION IN THE FORM OF %##- TECHNIQUES BECOMES NECESSARY %##- 4ECHNIQUES  %LECTRONIC PROTECTION FOR /4( RADAR ANTENNA ARRAYS CAN BE  PROVIDED IN THE FORM OF ADAPTIVE SIGNAL PROCESSING IN SPACE AND TIME 4HE STOCHASTIC CONSTRAINTS ADAPTIVE BEAMFORMING AND 34!0 METHODS n WERE DEVELOPED SPECIFI 
 Since sound travels about 3 to 15 mm/µs on the surface of a SAW device, a 250 mm  quartz device (about the largest available), has a usable delay of about 70 µs for a  single pass.9 Also, because each SAW device is waveform specific, each waveform  requires a different design. SAW pulse compression devices depend on the interdigital transducer finger loca - tions or the surface-etched grating to determine its bandpass characteristics. Figure 8.7  shows three types of filter determination approaches. 
 CAVITY KLYSTRONS PROVIDE FULL OPERA 
   NO   PP n    !PRIL   , 7 -ARTINSON AND 2 * 3MITH  h$IGITAL MATCHED FILTERING WITH PIPELINED FLOATING POINT  FAST &OURIER TRANSFORMS &&4S  v  )%%% 4RANS ON !COUSTICS  3PEECH AND 3IGNAL 0ROCESSING    VOL !330 
 The atmosphere can be assitmed to be ttrrbulent  everywhere, but its intensity varies widely both in space and time. It is only when turbulence is  concentrated into regions of greater or lesser intensity than its surroundings that it is of  interest as an electromagnetic scatterer. There are at least two types of turbulent atmospherrc  formations that can result in angel activity. 
 LAW DETECTION IS USED  -OST 3!2 PROCESSORS SACRIFICE SOME SPATIAL RESOLUTION BY AVER 
 14.4 is more academic than practical. The solution for  other structures, such as infinite parabolic and elliptic cylinders, are difficult at best,  and for many structures whose surfaces may coincide with a coordinate system, there  is no convenient method of solution. The most useful and practical of the exact solutions available is that of the per - fectly conducting sphere, shown earlier in Figure 14.2. 
 D. J. Povejsil, R. 
 The wind vectors are  taken from combining data from three nearby dop - pler radars. ( Courtesy of American Meteorological  Society. From D.E. 
 12.5. Second Detector.—The purpose ofthe second detector isto produce arectified voltage that isproportional tothe amplitude ofthe i-fwaves. Inmost receivers itisimportant that this rectified voltage be proportional tothe first power ofthe i-famplitude (linear detector). 
 LATION USUALLY FREQUENCY OR PHASE MODULATION  TO OBTAIN THE ENERGY OF A LONG PULSE WITH THE RESOLUTION OF A SHORT PULSE #ONTINUOUS WAVE #7  RADAR  4HIS RADAR EMPLOYS A CONTINUOUS SINE WAVE )T ALMOST  ALWAYS USES THE DOPPLER FREQUENCY SHIFT FOR DETECTING MOVING TARGETS OR FOR MEASUR 
 The emphasis in this section is on altimeter precision. Sea-surface height measurements have become essential for a wide variety of appli - cations in oceanography, geodesy, geophysics, and climatology.63 With the exception  of near-polar ice, Earth-orbiting oceanographic altimeters have seen relatively little  application over nonaquatic surfaces. A satellite-based altimeter systematically circles the Earth, generating surface  height measurements along its nadir track. 
 BEAM  KLYSTRON AMPLIFIERS PERFORMANCE PARAMETERS AND DEVELOPMENT TRENDS v  )%%% 4RANS  VOL 03 
 Thin dielectric beads have been used assupports, but the disintegrating effect ofdielectric breakdown over thesurface ofthebead ishard toavoid. Reflections from thebeads can belargely canceled byproper spacing. 1However, bead-supported TABLE 11.1.—S1,ANDA~D MICROWAVE TRAMMISSION LINE Dimensior,s 01), in. 
 Zhou, C.F.; Gong, H.L.; Chen, B.B.; Zhu, F.; Duan, G.Y.; Gao, M.L.; Lu, W. Land subsidence under different land use in the eastern Beijing plain, China 2005–2013 revealed by insar timeseries analysis. Gisci. 
 PROCESSING LOSS TERM  /VALS OF #ASSINI  4HE FREE SPACE  MAXIMUM DETECTION CONTOUR OF A BISTATIC  RADARS BENCHMARK RANGE IS A CIRCLE OF RADIUS  2-  JUST AS IN THE MONOSTATIC CASE 3UCH  A CIRCLE ASSUMES CONSTANT RADAR CROSS 
 In the right-hand pic - ture, the aircraft could be detected if the target-to-clutter cross-section ratio were suf - ficient. Although this example is from many years ago,31 the principle is still the same,  even though current MTI improvement factors are better by tens of dBs. Restriction  of the IF dynamic range is still a very efficient way of normalizing clutter residue due  to system instabilities or clutter spectral spread to system noise. 
 ETRY LEADS TO RELATIVE TERRAIN HEIGHT ESTIMATION )F TWO OBSERVATIONS HAVE A TIME  DELAY CORRESPONDING TO THE REPEAT PERIOD OF THE ORBIT TYPICALLY  TO  DAYS   THEN SUB 
 It should be clear that any mean translational motion would change the absolute values of the measured radial velocities but would not affect the shear measurement. Armstrong and Donaldson62 were the first to use shear for severe storm detection. Azimuthal shear values of the order of 10~2 s"1 or greater and with vertical extent greater than the diameter of the mesocyclone are deemed necessary for a tornado to occur.63 Detection of the tornado vortex itself is not generally possible, since its hori- zontal extent may be only a few hundred meters. 
 ORDER PHASE ERROR IN  THE APERTURE AND CAUSES HIGHER SIDELOBES ON ONE SIDE OF THE BEAM &URTHERMORE  SUCH DISPLACEMENT WILL CAUSE THE BEAM TO MISPOINT )F THE DISPLACEMENT IS SMALL  FIXED  AND KNOWN  ONE CAN TYPICALLY CALIBRATE OUT THE FIXED MISPOINTING BIAS (OWEVER  IF THE DISPLACEMENT IS RANDOM  SAY CAUSED BY VIBRATION  THE BEAM POINTING ERROR CAN BE A PROBLEM 4HE REFLECTOR BEAM WILL BE STEERED BY  P RADIANS IF THE FEED IS DISPLACED OFF  AXIS BY AN AMOUNT D   P   ARCTANDF   RADIANS    WHERE F IS THE FOCAL LENGTH 3O IF THE LATERAL FEED DISPLACEMENT ERROR IS  D  THE BEAM  POINTING ERROR  $P  IS   $QE E    F F RADIANS    3T RUT "LOCKAGE 3TRUTS ARE USED TO SUPPORT THE FEED  AND FOR CENTER 
 ANGLE APPROXIMA 
 Meteorol. Soc. , vol. 
 ( I 1.16) was first introduce~! by Gabor4 and l1as  been used by Woodward5 in his treatment of detection and accuracy by means of inverse  probability. Both Gabor and Woodward define the e!Tective bandwidth in terms of the  complex-frequency representation, while the defl.nition presented above is in terms of the real  time waveforms. In essence, {/2 is the normalized second moment of the spectrum IS(J)l2  about the rm.·an (here taken to be al zero frequency). 
 SCAN PROBABILITY OF DETECTION  0 D VERSUS  RANGE FOR A GIVEN 2#3 TARGET IN A RECEIVER WITH UNLIMITED DYNAMIC RANGE )F IT IS DESIRED TO HAVE THE LOW 
 SPACE PATH LOSS   ,FS  EXPRESSED IN TERMS OF THE SPHERES RADIUS   R  AND WAVE 
 QUENTLY WERE OF LIMITED TACTICAL INTEREST 3PECIFICALLY  LOCAL OSCILLATOR PHASE INSTABILITIES  WERE REDUCED AND BISTATIC AUTOMATIC FOCUSING  AUTOFOCUS  ALGORITHMS WERE DEVELOPED  TO IMPROVE RANGE MEASUREMENT ACCURACY  FROM THE ANTENNA PHASE CENTER TO THE IMAGED  SCENE "ISTATIC AUTOFOCUS REQUIRES THAT THE POSITION OF BOTH TRANSMIT AND RECEIVE PLAT 
 THER REMOVED FROM THE FEED POINT 7HEN THE FREQUENCY IS CHANGED  THE PHASE AT THE RADIATING ELEMENTS CHANGES PROPORTIONATELY TO THE LENGTH OF FEED LINE SO THAT THE PHASE AT THE APERTURE TILTS IN A LINEAR MANNER AND THE BEAM IS SCANNED 4HIS EFFECT IS USEFUL FOR FREQUENCY 
 I(n)=n •E(n) . Radar System Engineeri ng Chapter 8 – Pulse Radar  60     Integration Loss for Incoherent Integration 1 10 100 1000 ^10000n Pfa=Tfa⋅B2F Pd=0.50 Pd=0.99Pd=0.90=10412 10 8 6 4 2 0=1012Integration loss L (n)dB n. number of pulses   Figure 8.15  Integration loss as a function of the integrated pulses n for non -coherent  integration. 
 The ratio of the bandwidths M therefore can be  unity when Br is large enough. 73 Both coded-pulse waveforms85 and frequency-modulated  waveforms have been considered for puls~ compression radar with CFAR.86  The benefits of a large Br for CF AR can also be obtained without transmitting a pulse­ compression waveform.87 A conventional pulse waveform can be transmitted, and on recep­ tion the received signal passed through a dispersive delay"line (a pulse expansion network) that  spreads the signal over a duration T. The output of the dispersive filter is hard limited and fed  to a second dispersive delay line with a characteristic inverse to the first. 
 Zebker, “Polarimetric radar measurements of a forested area  near Mt. Shasta,” IEEE Trans. on Geosc. 
 96. R. Klemm, Principles of Space-Time Adaptive Processing , 3rd Ed., London, UK: IET Radar,  Sonar and Navigation Series 21, 2006. 
 The value ofslant range computed bythis device isused toput arange marker onthe PPI atthe appropriate distance from the origin ofthe sweep. Taking afixwith theGPI involves turning theIi-S and E-W fixknobs until theintersection oftherange and azimuth marks appears ontop of anidentified target signal. The “fix” dials will then read the ground range ofthetarget from theaircraft, resolved into north-south and east- west components. 
 TRACKING PROBLEMS USING THE EQUATIONS IN 4ABLE  TO CALCULATE A GRAPH SUCH AS THE ONE SHOWN IN &IGURE  &OR SIMPLE TRACKING PROBLEMS  THE  @ 
 Any use is subject to the Terms of Use as given at the website. Meteorological Radar.  METEOROLOGICAL RADAR  19.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 their intensities measured by simply measuring the change in radial velocity with  azimuth angle, as shown in Figure 19.6. The radar scans in azimuth and detects a  couplet in radial velocity at constant range. 
 BEAM WIDTH THE WIDENING OF THE MAIN 
 These parameters were chosen to simplify the functional  description of the spectrum shape. In terms of the standard deviation of the spectral  width in m/s, these parameters can be defined as follows:  g v=⋅1 22σ- gaussi anspect r rum -polynomia l spectru vc v = ⋅ ⋅ 2 2ln( ) σ m m with 4 2- en v= =βσx xpone ntial spectrum (2.13) Assuming a value of σv=0 25. m/s, corresponding to windy condition, the three- clutter spectrum models are compared in Figure 2.12. 
 IRE, vol. 42.  pp. 
 Inthis “near zone” some parts ofthe ship lieonmaxima and some lieinthe nulls, and the net result atany instant issome sort ofaverage, in thefluctuations ofwhich one could hardly expect todiscern traces ofthe regular interference pattern predicted byEq. (29). The absence ofa sharply defined break inthe curve between the two regions isreadily justified onthe same grounds. 
  
 193-203, March, 1974.  42. Brennan, L. 
 TO 
 RESOLUTION PULSE COMPRESSION SYSTEMS 3PURIOUS $ISTORTION OF 2ADIATED 3PECTRUM  )T IS A SURPRISE TO MANY RADAR ENGI 
 5.2. Although the  details are quite different, the basic philosophy in PRF selection is to optimize long- range clear regions.  TR cPRIV VIT PRAc p A a tA=×+ =× +=2 0 25τλand and ceil. 
 DOPPLER hIMAGEv THAT COULD BE CALLED A h3!2v IMAGE  SINCE IT WAS FORMED FROM A COHERENT SEQUENCE OF PULSES  AND THE SUBSEQUENT COMPLEX PAIR 
 .....................  2  Basic Principle of Operation  ................................ ................................ 
 Anomalous differences provide a warning of the probable presence of a deception  jammer. When RGPO and VGPO operate simultaneously, the best defense is the contem - porary tracking of true and false targets in both range and doppler dimensions. The use of  multimode (high, low, and medium PRF) radars can also be an effective ECCM measure  helping to counter range-gate and velocity-gate stealers by switching radar modes. 
 The principle of the multiple-beam linear-beam tube has also been considered for  the traveling wave tube,9 but it is not obvious whether it has any significant advantages  over the MBK. Traveling Wave Tube (TWT).  The TWT linear-beam tube is similar to the  klystron in that the cathode, RF circuit, and collector are all separate from one another. 
 The ﬂowcharts of the RD algorithm and inverse RD algorithm are shown in Figure 2. 279. Sensors 2019 ,19, 1154 Spatial frequency domain  mapping            1D-FFT Motion compensation 2D-IFFT  ftk        rx kt K K   MfSt t SAR Image  Spatial frequency domain  mapping2D-FFT       rxKK k t    MfSt t         SAR Image   (a) (b)  Figure 2. 
 011~ t~~etliod of obtaitiitig the direction and the magnitude of tlie angular error in one  coordinate is by alternately switching the antenna beam between two positions (Fig. 5.1). This  is called lobe srvitcl~iriq, seqtterrtiol srvitcltirrg, or sequential lobirtg. 
 16.20 delay-line driving circuit isdesensitized byatrigger from the stable oscillator. This trigger does three other things: itgenerates asample video pulse which travels down theline; itoperates acoincidence circuit which examines thetime ofarrival from thecomparison amplifier ofthe preceding sample pulse; and finally after suitable delay itfires the transmitter and resensitize the echo circuits. The coincidence circuit supplies avariable d-cbias totheoscillator which keeps thefrequency of that oscillator instep with thesupersonic delay time asmeasured bythe sample pulses. 
 TION IS THE MOST COSTLY  USING A PAIR OF TURNTABLES SLAVED TOGETHER  ONE IN THE CEILING AND ONE ON THE FLOOR 4HE ECHO SIGNAL FROM A STRING DEPENDS ON THE LENGTH AND DIAMETER OF THE STRING   ITS TILT ANGLE WITH RESPECT TO THE INCIDENT WAVE  AND ITS DIELECTRIC CONSTANT .O MATTER WHAT THE TILT OF THE STRING  IT WILL BE PRESENTED NORMAL TO THE LINE OF SIGHT TWICE IN A COMPLETE ROTATION OF THE TARGET AND MAY CAUSE A SPIKE IN THE 2#3 PATTERN THAT COULD BE ERRONEOUSLY ATTRIBUTED TO THE TARGET UNLESS OTHERWISE ACCOUNTED FOR 4HE 2#3 OF A STRING RISES WITH THE FOURTH POWER OF ITS DIAMETER IN THE 2AYLEIGH REGION SEE &IGURE    AND FOR A GIVEN TENSILE STRENGTH  THE DIAMETER RISES ONLY AS THE SQUARE ROOT OF THE LOAD TO BE SUPPORTED 4HUS  BECAUSE THE ECHO SIGNAL INCREASES WITH THE SQUARE OF THE LOAD 
 TIAL FORM OF -AXWELLS EQUATIONS &)'52%   3UMMARY OF 2#3 LEVELS OF TARGETS DISCUSSED  IN THIS SECTION 4HE LOCATIONS  OF TARGETS ON THE CHART ARE GENE RAL  INDICATIONS ONLY. 
 26, 1951. 35. Pasqualucci, F., B. 
 1988 ,3, 32–35. [ CrossRef ] 12. Bamler, R. 
 HORN SQUARE  FOR EXAMPLE  WOULD BE CENTERED AT THE FOCAL PLANE )T PROVIDES SYMMETRY SO THAT WHEN THE SPOT IS CENTERED  EQUAL ENERGY FALLS ON EACH OF THE FOUR HORNS 4HE RADAR SENSES TARGET DISPLACEMENT FROM  THE ANTENNA AXIS THAT SHIFTS THE SPOT OFF OF THE  CENTER OF THE FOCAL PLANE BY MEASURING THE RESULTANT UNBALANCE OF ENERGY RECEIVED IN THE FOUR HORNS 4HIS IS ACCOMPLISHED BY USE OF MICROWAVE WAVEGUIDE HYBRIDS TO SUBTRACT OUTPUTS OF PAIRS OF HORNS  PROVIDING A SENSITIVE DEVICE THAT GIVES SIGNAL OUT 
   
 This  technique works best over surfaces with large reflection coefficient, and when the pulse widths  2p  1--'o .. ,~ 'o---~ Figure 14.11 Idealized echo response of a point target  located above a reflecting surface, for the case where  the pulse width is less than the time separation 10 be­ tween the direct and surface-reflected signals. The sur­ face reflection coefficient is p. 
 WAVE 2& STRUCTURE  AS IN THE ILLUSTRATION SHOWN IN &IGURE  4HE ELECTRON BEAM IS SIMILAR TO  &)'52%  2EPRESENTATION OF THE PRINCIPLE PARTS OF A TRAVELING WAVE TUBE   SHOWING A HELIX SLOW 
 For the higher wind speeds and fully developed seas encountered in the North Atlantic, the population of this sea-spike sector (the percentage of sea spikes) was found to grow as the 3.5th power of the wind speed, which, interestingly, is the same wind-speed dependence shown by the percentage of whitecaps seen on the surface.36 a (dB) FIG. 13.12 Segmented clutter probability distributions at low grazing angles. (Based on Trizna.34) It should be kept in mind that, to the extent that the sea surface may be viewed as a stationary homogeneous process, as it generally is over the duration and spatial extent of any particular experimental event, the scattering cross sec- tion may be said to be ergodic, which means that the statistical results obtained by time averaging from a small cell are equivalent to a shorter time average from a larger cell, provided that the number of "samples" is the same in the two cases. 
 2018 ,15, 252–256. [ CrossRef ] 16. Viviani, F.; Michelini, A.; Mayer, L.; Conni, F. 
 AP-24. pp.  R06 814. 
 D"  LIMIT ON IMPROVEMENT FACTOR  TO THE TRANSMITTER  AND  THIS REQUIRED THAT THE RMS PULSE 
 FIELD REQUIREMENT  FOR A VARIETY OF FREQUENCIES AND TARGET SIZES %RRORS ATTRIBUTABLE TO RADAR INSTRUMENTATION SHOULD BE HELD TO  D" OR LESS  WHICH  REQUIRES CAREFUL DESIGN AND SELECTION OF COMPONENTS 4HE DRIFT IN SYSTEM SENSITIVITY SHOULD NOT EXCEED THIS VALUE FOR THE TIME IT TAKES TO RECORD A SINGLE 2#3 PATTERN  WHICH SOMETIMES MAY APPROACH AN HOUR 4HE DYNAMIC RANGE OF THE SYSTEM SHOULD BE AT LEAST  D"  WITH  D" PREFERRED  ,INEARITY OVER THIS  RANGE SHOULD BE  D" OR BETTER  AND  IF NOT  STEPS SHOULD BE TAKEN TO CORRECT MEASURED DATA VIA CALIBRATION OF THE RECEIVER TRANSFER FUNCTION GAIN CHARACTERISTICS  2#3 MEASUREMENTS SHOULD BE CALIBRATED BY THE  SUBSTITUTION METHOD  IN WHICH AN  OBJECT OF KNOWN SCATTERING CHARACTERISTICS IS SUBSTITUTED FOR THE TARGET UNDER TEST 'IVEN THE KNOWN MEASURED OR CALIBRATED  RECEIVER GAIN CHARACTERISTICS  THIS ESTABLISHES THE CON 
 (ILL      PP n  7 'ABRIEL  h.ONLINEAR SPECTRAL ANALYSIS AND ADAPTIVE ARRAY SUPERRESOLUTION TECHNIQUES v .2,  2EPORT     APPROVED FOR UNLIMITED PUBLIC DISTRIBUTION  * !SENSTORFER  4 #OX  AND $ 7ILKSCH  h4ACTICAL DATA LINK SYSTEMS AND THE !USTRALIAN DEFENSE  FORCE !$& 
 STATE UNIT WAS INSTALLED AS A DIRECT RETROFIT 4HIS WAS NOT QUITE AS DIFFICULT AS USUAL  BECAUSE THE TUBE 
 Radar sensors are used apart from the distance and obstacle controls in the range up to 250 m and eventually will be used additionally for close -range sensing to  approximately 5 m (city traffic, airbag sensors, etc.), used as impact sensors (airbags, seatbelt control), for complete angle sensing (lane changing), and so forth.  It is anticipated that close - range sensing will be controlled with sensors operating at 24 GHz.  A drastic drop in pr ice is  also expected in the coming years. 
 Feature extraction is a key step in ship classiﬁcation. Researchers widely used geometric features, scattering features in feature extraction [ 5]. For geometric features, it contains ship area, ship rectangularity, moment of inertia, fractal dimension, spindle direction angle and ratio of length to width [ 6], etc. 
 The result of ky1−(kr−krc)is shown in Figure 8. The slope greater than 0 represents the bandwidth of ky1is greater than the bandwidth ofkr. In the images of different views, the bandwidth of ky1is inconsistent and there is a slight change in the range resolution of the time domain. 
 Control electrodes avoid the need for a full-power cathode-pulse modulator. A mod-anode (modu- lating anode) can be used in any linear-beam tube; it acts like a control grid with . a mu of 1 and is inexpensive and reliable. 
 SIDERING THE WEIGHTING OF THE ELEMENTAL PATTERN OR THE FEED DISTRIBUTION  THE INHERENT  SIDELOBE PATTERN CAN OBSCURE THE MAIN 
 576 INDEX  Incidence angle, 473  Index of refraction, for air, 448  Insects, 510  Integration improvement factor, 30-31  for Swerling models, 49  Integration loss, 30-33  Integration, of radar pulses, 29-33  Integrators, 388-392  Interclutter visibility, 130, 494-495  Interferometer:  in height finding, 545  radar, 165  Intermediate-frequency receiver, CW radar, 74  Interrupted CW (ICW), 147  Inverse probability receiver, 377-379  Inverse SAR, 528-529  Inverse scattering, 437-438  Inverted coaxial magnetron, 195  Ion oscillations, 74  Ionosphere, 530  IREPS, 456  Isolation, in CW radar, 71-73  in FM-CW radar, 88-91  Kalman filter, 185  Kalmus clutter filter, 497  Keep-alive, in TR tube, 362-363  Klystron amplifier, 200-205  Knife-edge ambiguity diagram, 418-419  Lambert surface, 497  Land clutter, 489-498  at millimeter wavelengths, 563  Laser radar, 564-566  Latching ferrite phase shifters, 293-294  Lens antennas, 248-254  Lens array, 308-309  letter-band nomenclature, 8  Likelihood-ratio receiver, 377, 379  Limited-scan arrays, 334  Limiting, in MTI, 136-138  Limiting loss, 59  Lin-log receiver, 507  Linear array, 279  Linear beam tubes, 200-208  Linear FM pulse compression, 422-427  Linear recursive sequences, 429  Line-of-sight stabilization, 270  Line-type modulator, 214-215  Loaded-line phase shifter, 289  Lobe recognition, in height finding, 546  Lobe switching, 153  Lobing, due to multipath, 442-447 Log-FTC, 506-507  and sea clutter, 486-488  Log-,log.receiver, 486-488  Log normal probability density function, 51  and sea clutter, 479  Logarithmic detector, 384  LORO, 159  Loss, integration, 30-33  Losses, system, 56-61  Low-angle tracking, 172-176  Low-noise front ends, 351-353  Low-sidelobe antenna, 227-228, 333, 549  Luneburg lens, 252-253  m-out-of-ri detector, 388-390, 486  Magnetron, 192-200  Man, radar cross section of, 44  Matched filter, 5, 16, 369-375  in FM-CW radar, 91-92  Maximal length sequences, 429  Maximum unambiguous range, 2-3  Measurement accuracy, 400-411  Median detector, 486  Metal-plate Jens, 250-252  Metal space-frame radome, 266  Metallic radomes, 268  METRRA, 437 )  Microwave radiation hazards, 465-466  Microwave refractometer, 455  Mie region, 34  Millimeter wave radar, 560-564  Minimum detectable signal, 16-18  Mirror-scan antenna, 242-244  Mixer-matrix feed, 305, 308  Mixers, 347-351  Modulating anode, 201, 203  Modulators, 214-216  Module, solid-state, 217-218  Monopulse radar, 160-167, 182-183  in height finding, 543  and high-range-resolution, 181 182, 435  Monostatic radar, 553  MOPA (master-oscillator power amplifier), 106  MOSAR, 315  Motor drives, for antennas, 273  Moving Target Detector, 127-129  Moving target indication (see MTI}  Moving-window detector, 184, 388-390  MTD, 127-129  MTI radar, 101-148  acoustic delay line, 126  AID converter, 120  adaptive, 142 . M.T.1.:  adaptive array, 145  cancellation ratio, 130  canonical comb filter, 112  charge transfer device. 126  clutter attenuation. 
 DENCE v )%%% 4RANS  VOL !0 
 WAVE SCATTERING FROM THE SEA &IGURE  COMPARES A SAMPLE OF .2, &2 DATA TAKEN AT HIGH WIND SPEEDS      KN  WITH THE PREDICTIONS OF THE PURE  30- "RAGG MODEL IN THE FORM OF %Q    FOR 6 
 Oct 11 15.  1976. pp. 
 The chapter on radar clutter (Chap. 13) has been reorganized to include methods for the  detection of targets in the presence of clutter. Generally, the design techniques necessary for  the detection of targets in a clutter· background are considerably different from.those necessary  for detection in a noise background. 
 TION  AND THAT A CLUTTER MAP LOSS BASED ON THE SINGLE 
 Multiple-delay cancelers have wider clutter rejection notches than single-delay cancelers. The wider rejec- tion notch encompasses more of the clutter spectrum and thus increases the MTI improvement factor attainable with a given clutter spectral distribution. When a number of single-delay feedforward cancelers are cascaded in series, the overall filter voltage response is k2n sin" (ir/^7), where k is the target ampli- tude, n is the number of delays, fd is the doppler frequency, and T is the interpulse period.15 The cascaded single-delay cancelers can be rearranged as a transversal filter, and the weights for each pulse are the binomial coefficients with alternating sign: 1, -1 for two pulses; 1, -2, 1 for three pulses; 1, -3,3, -1 for four pulses, etc. 
 BORNE WIND TRACING SCATTERERS ARE SMALL AND OBEY 2AYLEIGH SCATTERING CROSS SECTION PHYSICS 8 
 If the large noise spikes are not  limited and are allowed to pass they would sllock-excite tile tlarrowband IF ampliticr and  produce an output pulse much wider in duration than the input pulse. Therefore the interfer-  ence would be in the receiver for a much longer time and at a higher energy level than when  limited before narrowbanding. Desired signals which appear simultaneously with the noise  spike might not be detected, but the circuit does not allow the noise to influence the receiver  for a time longer than the duration of a noise spike. 
 S HS4 A4.      .OTE  THAT IN THE DENOMINATOR OF THIS EXPRESSION THE GAIN DUE TO THE ARRAY FACTOR  . IS REDUCED BY THE APERTURE EFFICIENCY  GA AND BY THE ERROR POWER LOST FROM THE MAIN  BEAM   
 Even within themajor units oftheset, subassemblies have been designed forreplacement intheevent offailure. External test points” have been provided onthe transmitter-receiver and thesynchronizer power supply toaidinidentifying defective units incases offailure. On the transmitter-receiver these include atest trigger from the modulator, anextra video channel, and alead from a directional coupler which enables r-fchecking. 
 rr 197 207. March. 1971  76. 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 7 .52  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 Because the curves cross one another, one can ensure that Pe ≤ 0.01 for any m by setting  R equal to the maximum value of any curve for each value of n. The algorithm was evaluated by using simulations and recorded data. 
  "     
 665-669, Decem­ her. 1966.  55. 
 BEAM TUBES AS AMPLIFIERS CAN PRODUCE HIGH POWER WITH GOOD EFFICIENCY AND HIGH GAIN AND WITH WIDE BANDWIDTH 4HEY HAVE BEEN CAPABLE OF PRODUCING AVERAGE POWERS OF A MEGAWATT  AS WELL AS AVERAGE POWERS OF MANY KILOWATTS IN A SIZE SUITABLE FOR USE IN A MILITARY FIGHTERATTACK AIRCRAFT +LYSTRON 4HE KLYSTRON AMPLIFIER HAS BEEN AN IMPORTANT 2& POWER SOURCE FOR  MANY RADAR APPLICATIONS !S MENTIONED  IT IS CAPABLE OF HIGH AVERAGE AND HIGH PEAK POWER  HIGH GAIN  GOOD EFFICIENCY  STABLE OPERATION  LOW INTERPULSE NOISE  LARGE BAND 
 The signal is defined as a short- duration pulse return from the direction determined by the quiescent weights and at a doppler frequency corresponding to half of the PRF. Independent quiescent weights for each subchannel could be utilized to optimize the doppler response for another frequency. Performance Capability of Space-Time Adaptive Arrays. 
 1 1 - 17, January. 1976.  51. 
 1977, pp. 145-149, IEE (London) Conference Publi­ cation 110. 155. 
 TIVE CALIBRATION  FROM THE TARGET BEING MEASURED AND FROM A  STANDARD TARGET 3TANDARD  TARGETS MAY BE METAL SPHERES  ,UNEBURG 
 K. Raney, “The delay doppler radar altimeter,” IEEE Transactions on Geoscience and Remote  Sensing , vol. 36, pp. 
 It is not often used.  Blip-scan ratio. This is the same as the single-scan probability of detection. 
 (31) shows that iftwo radar sets, operating atwavelengths Xland x2,receive equal signals from atarget inthefree-space region, the ratio ofrespective signal strengths intheregion towhich Eq. (31) applies will beS1/S2 =(~2/~1) 4. Figure 2.12 records some radar observations made attwo wavelengths with the same ship asthe target. 
 PULSE PHASE SHIFT V D4P OF THE CLUTTER RETURN 4HIS PROVIDES A VERY SENSITIVE ERROR SIGNAL 4HE AVER 
 Since the timing is controlled by a digital clock, the delay  can be made very stable, just as with digital processors. However, no A/Dor D/A converters  are required as in digital systems. It has been claimed that such devices are more economical in  cost, consume less power, are of less size, and of greater reliability than digital processing. 
 Under some conditions this precession causes thegyro toindicate afalse vertical, thus producing serious errors inthestabilization system. Although inthe above example the gyro ismounted onthe rotating yoke, the effects ofprecession are avoided inthe most recent designs bymounting the gyro ontheairframe and providing atake-off oneach gimbal axis. Avoltage indicating the correct tilt angle isfed tothe servoamplifier. 
 STATE POWER AMPLIFIERS 330!S   ONE FOR EACH WAVEGUIDE 4HE  
 MTI AND PULSE DOPPLER RADAR 131  This would arrly 10 the coho Jocking or to the phase change introduced by a power amplifier.  A phase change pulse-to-pulse of 0.01 radians results in an improvement-factor limitation of  40 dB. The limits to the improvement factor imposed by pulse-to-pulse instability are listed  below:A.46.47  Transmitter frequency  Sta lo or coho frequency  Transmitter phase shift  Coho locking  Pulse timing  Pulse width  Pulse amplitude (m:\fr r 2  (2rr llJTr2  (ll</J r 2  (ll<t> r 2  r2 /(llt)22Br  r2/(llr}2Br  (A/llA)2  where llf = interpulse frequency change, r = pulse width, T = transmission time to and from  target. 
 M. R. Winkler, and N. 
 CONTROLLED TUBE IS A MODERN VERSION OF THE CLASSICAL TRIODE OR TETRODE VACUUM TUBE THAT DATES BACK TO THE EARLY YEARS OF THE TH CENTURY 4HESE DEVICES EMPLOY A  CATHODE TO GENERATE ELECTRONS  ONE FOR A TRIODE  OR TWO FOR A TETRODE  CONTROL GRIDS   AND AN ANODE TO COLLECT THE ELECTRONS ! SMALL VOLTAGE APPLIED TO THE CONTROL GRID ACTS TO CONTROL THE NUMBER OF ELECTRONS TRAVELING FROM CATHODE TO ANODE 4HE PROCESS BY WHICH THE ELECTRON DENSITY OF THE ELECTRON STREAM IS MODULATED BY THE SIGNAL ON THE CONTROL GRID TO PRODUCE AMPLIFICATION IS CALLED  DENSITY MODULATION )N THE LATTER HALF OF THE TH  CENTURY  GRID 
 The transmitted reference sequence is fed into the ref- erence shift register. The received input sequence is continuously clocked into the signal shift register. In each clock period the comparison counter forms the sum of the matches minus the sum of the mismatches between corresponding stages of the two shift registers, which is the output correlation function. 
 The classical magnetron is of  low cost, convenient size and weight, and high efficiency, and has an operating voltage low  enough not to generate dangerous X-rays. The coaxial magnetron improves on the classical  magnetron by providing greater reliability, longer life, and better stability. 192 INTRODUCTION TO RADAR SYSTEMS  The klystron amplifier provides the radar system designer with high power, high gain,  good efficiency, and stability for MTI and pulse-compression applications. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 7 .38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 Association of Accepted Detection with Existing Tracks. 
 (b) FIG. 18.17 (0) Wavefront phase relationships in a phase comparison monopulse radar. (/?) Block diagram of a phase comparison monopulse radar (one angle coordinate). 
 A precision exponentially decaying IF waveform from a test set is applied to the unit under test. The unit is adjusted for a linearly decaying output, which indicates the correct adjustment. Dynamic Range. 
 All terms Iξη, Tξη and Rξη contri b- ute to the determination of Sξη as complex magnitudes.  The error model itself is constructed  based upon this scattering parameter description of the signal path.  The measured magnitudes  (m) result from the corrected magnitudes (c) due to additive and multiplicative error influences. 
 SIGHT APPLICATIONS AT SHORT RANGE 4HIS CHAPTER FOCUSES PREDOMINANTLY ON SKYWAVE RADAR  THOUGH MUCH OF THE  DISCUSSION APPLIES EQUALLY TO SURFACE  WAVE RADAR 2ATHER THAN  AMALGAMATE DISCUSSION OF THE TWO RADAR CONFIGURATIONS THROUGHOUT THE CHAPTER  THE DISTINCTIVE FEATURES OF (& SURFACE WAVE RADAR ARE TREATED SEPARATELY IN AN APPENDIX AT THE END OF THE CHAPTER )N ONE SENSE THE DEVELOPMENT OF (& SKYWAVE RADAR CAN BE TRACED BACK TO THE S   WHEN SKYWAVE ECHOES WERE IDENTIFIED   BUT THE FIRST (& RADAR SYSTEMS WERE NOT DEPLOYED  UNTIL THE S 3INCE THEN  SKYWAVE RADAR HAS EVOLVED TO ADDRESS APPLICATIONS SUCH  AS THE DETECTION AND TRACKING OF AIRCRAFT  BALLISTIC AND CRUISE MISSILES  AND SHIPSn )N  ADDITION TO DETECTING hSKINv ECHOES FROM TARGETS OF INTEREST  (& RADAR IS USEFUL FOR OBSERV 
 In practice, performance is limited by the ability to produce the required illu- mination function. As the displacement increases, a larger physical aperture size is required to produce the desired virtual aperture size owing to beam spreading. This can be seen in Fig. 
 POINT  COMPUTATIONS ARE USED  THEN THIS INCREASED DYNAMIC RANGE RESULTS IN A GROWTH IN THE NUMBER OF BITS REQUIRED TO REPRESENT THE VALUES  AND THERE NEEDS TO BE A STRATEGY TO ACCOMMODATE IT 4HERE ARE SEVERAL TECHNIQUES GENERALLY USED TO HANDLE THIS INCREASED DYNAMIC RANGE  IN FIXED 
 Constant False-Alarm Rate (CFAR). A constant false-alarm rate in the presence of variable levels of noise is usually a requirement placed on any modern radar. It is very easily achieved in CW radars by the use of filter banks or FFTs. 
             
 pp. 36 40. Oct. 
 (A collec-  tion of 38 reprints on sea, land, and atmospheric clutter.)  37. I);~lcy. J. 
 NIQUE SHOWN IN &IGURE  B IS JUSTIFIED 3OMETIMES  2  'T  OR BOTH ARE ASSUMED CON 
 7.23a is shown the pattern E(tj,) and the sampled  points spaced A./d radians apart. The sampled values E,(nl/d), which determine the antenna  pattern, are shown in b.  The antenna pattern Ea(tj,) can be constructed from the sample values Ei11l/d) with a  pattern of the form (sin iJ, )N about each of the sampled values, where iJ, = rr(d/l) sin tj,. 
 326-337, May, 1975. (Also available in ref. 1.)  7. 
 CIALLY IN AIRBORNE ENVIRONMENTS WHERE HIGH VIBRATION LEVELS ARE PRESENT 4HE VIBRATION SENSITIVITY OF AN OSCILLATOR IS SPECIFIED BY THE FACTIONAL FREQUENCY VIBRATION SENSITIVITY  COMMONLY KNOW AS THE  G 
 For satisfactory operation, however, the tube will exhibit about thesame input impedance values. Exact figures can beobtained from performance charts. Pulse-1ength Limitations.—The early experiments ofthe British with high-power pulse techniques revealed acharacteristic ofoxide cathodes which isresponsible inlarge measure forthehigh pulse power ofmagne- trons. 
 Moore, K. A. Soofi, and S. 
 4.Gabor,D.:TheoryofCommunication, J.lEE,pI.III,vol.93,pp.429-441, 1946. 5.Woodward, P.M.:..Probability andInformation Theory, withApplications toRadar,"chap.6, McGraw-Hill BookCo.,NewYork,1953. 6.Skolnik, M.I.:Theoretical Accuracy ofRadarMeasurements, IRETrans.,vol.ANE·7,pp.123-129, December, 1960. 
 AZIMUTH CELL IF THE NEW VALUE EXCEEDS THE AVERAGE BACKGROUND LEVEL BY A SPECIFIED AMOUNT /PTIMAL  $ETECTOR  4HE RADAR DETECTION PROBLEM IS A BINARY HYPOTHESIS 
 LIMITED MODEL IS APPROPRIATE  BUT THERE ARE TWO IMPORTANT SITUATIONS WHERE THIS IS NOT THE CASE 4HE FIRST IS SHIP DETECTION  WHERE THE INTRINSIC DOPPLER SPREAD OF SEA CLUTTER ROUTINELY EXTENDS BEYOND THE TYPICAL DOPPLER SHIFTS OF MOST SHIP ECHOES 4HE SECOND CASE IS THE PHENOMENON OF SPREAD DOPPLER CLUTTER  WHICH ARISES FROM PLASMA INSTABILITIES AND TURBULENCE  ESPECIALLY POST 
 BACK RATIOS ON THE ANTENNAS  EMPLOYING VERTICAL NULLING IF AVAILABLE  AND USING ADAPTIVE SIGNAL PROCESSING TECHNIQUES OR AT LEAST MAINTAINING LOW RECEIVE ARRAY SIDELOBES  ARE ALL EFFECTIVE TOOLS FOR MITIGATING AURORAL  METEOR  AND OTHER IONOSPHERIC CLUTTER Óä°Ê  "- 
 1425. Inany multi-output dynamotor only one voltage can beregulated, but, except inthe event ofvery unevenly loaded circuits, the unregulated voltages will closely follow the regulated voltage. Regulation can behandled in several ways: (1)alloutput circuits have windings onthe booster arma- ture although only one ofthem iscontrolled (Fig. 
 We used Leaky ReLU as our activation function. To avoid the problem of over-ﬁtting, dropout has been used [ 35].   (a) ( b)  Figure 1. 
 Far more important, when the information tobetransmitted has been @hered byamodern long-range, high-definition radar, isthelow traffic-handling capacity ofthe system oftelling and plotting. Literally hundreds of targets may show atagiven time ontheindicator ofsuch aradar asthe first one described inChap. 15;anattempt toconvey with adequate accuracy and speed theinformation provided atarate offour sweeps per minute ishopeless under such conditions. 
 Shorter- range and airborne weather radars often employ beamwidths of between 2 and 3°. Operational weather radars normally are capable of short- and long-pulse op- eration in the range of 0.5 JJLS to about 6 jxs. Through pulse-width diversity, high resolution is obtained, usually at short range, while for long-range detection longer pulses provide increased sensitivity and tend to equalize the along-beam and cross-beam resolutions. 
 Certain atmospheric conditions will produce a modiﬁcation of thisnormal refraction.. 15A BASIC RADAR SYSTEM RADAR SYSTEM CONSTANTS Beforedescribingthefunctionsofthecomponentsofamarineradar,thereare certain constants associated with any radar system that will be discussed. Theseare carrier frequency, pulse repetition frequency, pulse length, and powerrelation. 
 #ARVER  AND 4 ,EE  h-0!2 PROGRAM  OVERVIEW AND STATUS v PRESENTED AT  RD )NT #ONF ON )NTERACT )NFO 0ROC 3YS ))03    !-3  3AN  !NTONIO    4 -AESE  * -ELODY  3 +ATZ  - /LSTER  7 3ABIN  ! &REEDMAN  AND ( /WEN  h$UAL 
      (n n     
 M. Headrick, R. W. 
 transmitter  power (kW)160 300 1200 200 50 1500  Tx gain (dB) 18–27 23 ERP 76 dBW 80 dBW 80 dBW 75 dBWTABLE 20.2  Principal Design Parameters for Some Major HF Skywave Radar Systems,   Past and Present   (This information has been compiled from sources that, in some cases, are incomplete. Where only  partial information is provided, it may still be useful for comparison purposes. Notes: (i) VLPA  denotes vertical log-periodic antenna and (ii) 2-band ( n-band) linear arrays are usually constructed as  contiguous collinear arrays.) ch20.indd   11 12/20/07   1:15:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
        
 If the receiver gain is too low, features at or near theshoreline, which would reﬂect echoes at a higher gain setting, will notappear as part of the landmass image. If the receiver gain is too high, thelandmass image on the PPI will “bloom”. With blooming the shoreline willappear closer than it actually is. 
 TERED IN MATCHING THE RADIATING ELEMENTS AND IN MAINTAINING POLARIZATION PURITY 4HE DISCUSSION IN THIS CHAPTER WILL CONCENTRATE ON PLANAR PHASED ARRAYS  RATHER THAN CON 
 Therefore, we emphasize on increasing the equivalent number of pulses in each CPI by exploiting the spatial continuity information. By exploiting the spatial continuity information, the forward pulses and the backward pulses outside the measured CPI can be predicated by taking the advantage of the autoregressive (AR) 74. Sensors 2019 ,19, 1920 technique [ 20,21]. 
 Radar System Engineering  Chapter 9 – Synthetic Aperture Radar  84        Figure 9.8  Resolution of two signals.     If two neighbouring points reproduce two (sin x/x)2  responses, then they can be directly r e- solved if the envelopes are “cut” within the 3 dB points.  Here applies:   € sinx x        2 =.5 with x=1.4rad[] (10.32)  The distance of the maximums is 2x:   02 20 sin 42 θλ π TvR xt ⋅ =Δ  (10.33)  Replace  € v⋅T=L and calculate the resolution to obtain the following:   020 sin1 48.2 θλ π LRDtv ⋅ ==Δ  (10.34)  Other results for the resolution D are stated in literature, for example in [24], which results  from different approximations within the processing. 
 21.8  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 The field at a distance z from the source is given by  E zt E e ez j t z( ,)( )= ⋅ ⋅− ⋅ ⋅ − ⋅ 0α ω b (21.4) The wavelength, l, in the medium is in meters,  λπ= =2 bv f (21.5) where f is frequency in Hertz. The losses in such systems are described in terms of tangents of loss angles, d,  between electric and magnetic fields. The electrical loss tangent is given by tanδε εσ ωεe=′′ ′+′, which can be simplified to tanδσ ωεe≈′ for low loss materials      (21.6) representing the sum of the charge transport and polarization relaxation losses, and the  phase angle between electric field and current density. 
 Ropor.t 7098. June 25, 1970 (AD 709897).  1. 
 TION CORRECTION TO AN INERTIAL PLATFORM !LTHOUGH '03 UPDATES ARE COMMONLY USED TO  PROVIDE NAVIGATION IN MANY SITUATIONS  A MILITARY AIRCRAFT CANNOT DEPEND SOLELY ON ITS AVAILABILITY &URTHERMORE  INERTIAL SENSORS ARE USED TO FILL IN BETWEEN '03 MEASURE 
 Preliminary result of high resolution multi-aspect SAR imaging experiment. In Proceedings of the 2016 CIE International Conference on Radar (RADAR), Guangzhou, China, 10–13 October 2016; pp. 1–3. 
 UNPRECEDENTED ACCURACY  FOR WHICH A NON 
 There are other probahility-density functions of interest in radar, such as the Rice, log normal,  and the chi square. These will he introduced as needed.  Another mathematical description of statistical phenomena is the probability distrih11tio11  fi111ctio11 l'(x). 
 Data can betransferred interms ofthe frequency ofasingle train ofpulses, the degree of IAsubcarrier isasine wave, usually intheaudio- orvideo-frequency range, which, after ithas hem modulsted bythe information-bearing signals, isused tomodulate an r-f,carrier,. 684 RADAR RELAY [SEC. 17.3 staggering oftwo trains, orthe lapse oftime between a“basic” pulse which isone ofatrain and asecond pulse occurring acon- trolled time later inthesame cycle. 
 Comparison of bistatic and monostatic radars. It is difficult to make a precise comparison of  bistatic and monostatic radars because of the dissimilarity in their geometries. The coverage of  a monostatic radar is basically hemispherical. 
  P 2     WHERE TERMS ARE DEFINED IN &IGURE  4HE LOCUS OF POINTS FOR CONSTANT DOPPLER SHIFT ON THE %ARTHS SURFACE IS CALLED AN  ISODOPPLER CONTOUR  OR  ISODOP #LUTTER RETURNS ARE CHARACTERIZED BY THESE ISODOPS   WHICH ARE CALLED  CLUTTER DOPPLER SHIFT  )N THE MONOSTATIC CASE AND A FLAT %ARTH  THESE  ISODOPS ARE CONIC SECTIONS IN THREE DIMENSIONS AND RADIAL LINES EMANATING FROM THE RADAR IN TWO DIMENSIONS "ECAUSE THESE ISODOPS ARE ALIGNED WITH THE RADARS LOOK ANGLE  THE CLUTTER IS CALLED  STATIONARY )N THE BISTATIC CASE  THE ISODOPS ARE SKEWED  AWAY FROM THE LOOK ANGLE  DEPENDING UPON THE GEOMETRY AND PLATFORM MOTION  AND THE CLUTTER IS CALLED  NONSTATIONARY "ISTATIC ISODOPS ARE DEVELOPED ANALYTICALLY FOR  TWO DIMENSIONS AND A FLAT EARTH BY SETTING  F 42   CONSTANT IN %Q  AND SOLVING  FOR P2 OR P 4  IF APPROPRIATE  &IGURE  IS A PLOT OF BISTATIC ISODOPS IN A TWO 
 Thelessthespillover, thehigher theefficiency. However. theillumination ismoretapered, causingareduction intheaperture efficiency. 
 GATED HIGH 02& 2'(02&  PERFORMANCE IS  DRAMATICALLY BETTER FOR DETECTION OF HIGHER SPEED CLOSING TARGETS    2ANGE GATES  ARE OFTEN SMALLER THAN RANGE RESOLUTION CELLS OR BINS  2'(02& PRODUCES THE LONGEST  DETECTION RANGE AGAINST CLOSING LOW CROSS SECTION TARGETS 5LTRA 
 Linear-beam  tubes as amplifiers can produce high power with good efficiency and high gain and with  wide bandwidth. They have been capable of producing average powers of a megawatt,  as well as average powers of many kilowatts in a size suitable for use in a military  fighter/attack aircraft. Klystron. 
 SPACE 34!0 ARCHITECTURES 4HIS TRANSFOR 
 D.: Exact Derivation of the Doppler Shift Formula for a Radar Echo Without Using  Transformation Equations, Am. J. Phys., vol. 
 The AGC results in a constant angle sensitivity independent of target size and range.  With AGC the output of the angle-error detector is proportional to the dilTarence signal  normalized (divided) by the sum signal. The output of the sum channel is constant. 
 Noise that arises from  lightning-stroke radiation is called atmospheric noise (not to be confused with noise produced  by atmospheric absorption as described previously). The spectrum of atmospheric noise falls  of rapidly with increasing frequency and is usually of little consequence above 50 MHz.54  Hence atmospheric noise is seldom an important consideration in radar design, except, per­ haps, for radars in the lower VHF region.  Another source of noise predominant at the lower radar frequencies is urban noise, also  known as man-made noise. 
 CONTROLLED TUBES HAVE BEEN OPERATED AT 5(& AND HIGHER FREQUENCIES BY USING MICROWAVE TECHNIQUES IN THEIR CONSTRUCTION  AS WAS DONE IN THE #OAXITRON 4HEY CAN ALSO BE MADE TO OPERATE WITH CONSTANT EFFICIENCY WHEN SHAPING OF THE PULSE AMPLITUDE IS USED TO REDUCE INTERFERENCE CAUSED BY ITS FAR 
 FIELD CRITERION OFTEN REQUIRES THAT THE RANGE TO THE TARGET BE SEVERAL THOUSAND FEET SEE &IGURE   "ECAUSE THE TYPICAL TARGET HEIGHT ABOVE THE GROUND IS A FEW DOZEN FEET AT BEST  THE ELEVATION ANGLE TO THE TARGET AS SEEN FROM THE RADAR IS  AT MOST AND OFTEN LESS !T SUCH LOW GRAZING ANGLES  THE GROUND IS STRONGLY ILLUMINATED BY THE ANTENNAS  AND UNLESS THE GROUND BOUNCE CAN BE SUPPRESSED  THE TARGET WILL BE ILLUMINATED BY A MULTIPATH FIELD )N THE DESIGN OF AN OUTDOOR TEST RANGE  THEREFORE  A DECISION MUST BE MADE WHETHER TO EXPLOIT THE GROUND BOUNCE OR TO ATTEMPT TO DEFEAT IT )T IS GENERALLY EASIER TO EXPLOIT IT THAN TO ELIMINATE IT&)'52%   4HE METAL SUPPORT PYLON 4HE DESIGN  IS FOR AN INCIDENT WAVE ARRIVING FROM THE LEFT  2EPRINTED  WITH PERMISSION OF 3CI4ECH 0UBLISHING  )NC  . 
 At still higher elevation angles, RADAR SLANT RANGE (nmi) FIG. 6.25 Typical two-way coverage requirement example.HEIGHT (FEET) RANGELIMITHEIGHT LIMIT . CHAPTER 7 PHASED ARRAY RADAR ANTENNAS Theodore C. 
 Ashok, H.G.; Patil, D.R. Survey on Change Detection in SAR Images. In Proceedings of the IJCA Proceedings on National Conference on Emerging Trends in Computer Technology, Shirpur, India, 28–29 March 2014; pp. 
 The timing mark permits the time of transmission  and the time of return to be recognized. The sharper or more distinct the mark, the more  accurate the measurement of the transit time. But the more distinct the timing mark, the  broader will be the transmitted spectrum. 
 SYNTHETIC APERTURE RADAR  17 .116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 because we define LOS velocity as dR/dt, where R is the range to the target. Thus, a  positive dR/dt corresponds to a receding target and results in a negative doppler fre - quency shift, and a negative dR/dt corresponds to an incoming target and results in a  positive doppler frequency shift. Consider an airborne radar with an isotropic antenna pattern, with constant velocity  along a straight line parallel to a flat ground3 (Figure 17.4 a). 
 Radar observations of light precipitation show a horizontal" bright band" at an altitude  at which the temperature is just above 0°C. The measured reflectivity in the center of the bright  band is typically about 12 to 15 dB greater, than the reflectivity from the snow above it and  about 6 to 10 dB greater than the rain' below.70 The center of the bright band is generally from  about 100 to 400 m below the 0°C :isotherm. Although the bright band is relatively thin,  considerable attenuation can occur' when radar observations are made through it at low  elevations. 
 Normalizing with respect to the square of the width of the plane in the plane orthogonal to the measurement plane, we find the maximum sidelobe levels to be V-V (n-i8>w2 TT tan2 e . Note that this result is independent of the radar wavelength. The frequency independence of the principal-plane sidelobes is illustrated in Fig. 
 34, pp. 674–680,  1996. 113. 
 Inordertomaintain maximum effectiveness oftheradaranditscomputer whcnoverload­ ingoccurs,somesortofprioritysystemisrequired. Taskswhicharenotastimecriticalshould bedeferred sothathigh-priority taskscanbeaccomplished. Table8.2isanexample of apriority structure foratactical airdefense systeminwhichtheradarperforms search andautomatic tracking, aswellassupport missileengagements. 
 Theblockdiagram ofFig.1.2isasimplified versionthatomitsmanydetails.Itdoesnot includeseveraldevicesoftenfoundinradar,suchasmeansforautomatically compensating the receiverforchangesinfrequency (AFC)orgain(AGe),receivercircuitsforreducing interfer­ encefromotherradarsandfromunwanted signals,rotaryjointsinthetransmission linesto allowmovement oftheantenna, circuitry fordiscriminating between movingtargetsand unwanted stationary objects(MTnandpulsecompression forachieving theresolution benefits ofashortpulsebutwiththeenergyofalongpulse.Iftheradarisusedfortracking, some meansarenecessary forsensingtheangularlocation ofamovingtargetandallowing the antenna automatically tolock-onandtotrackthetarget.Monitoring devicesareusually included toensurethatthetransmitter isdelivering thepropershapepulseattheproper powerlevelandthatthereceiversensitivity hasnotdegraded. Provisions mayalsobein­ corporated intheradarforlocatingequipment failuressothatfaultycircuitscanbeeasily foundandreplaced. Insteadofdisplaying the"raw·video" outputofasurveillance radardirectlyontheCRT, itmightfirstbeprocessed byanautomatic 'detection andtracking (ADT)devicethatquantizes theradarcoverage intorange-azimuth resolution cells,adds(orintegrates) alltheechopulses received withineachcell,establishes athreshold (onthebasisoftheseintegrated pulses)that permitsonlythestrongoutputsduetotargetechoestopasswhilerejecting noise,establishes andmaintains thetracks(trajectories) ofeachtarget,anddisplays theprocessed information. 
 It finds application where large variations of input  signals are expected. It might be used to prevent receiver saturation or to reduce the effects  of unwanted clutter targets in certain types of non-MTI radar receivers (Sec. 13.8). 
 If a signal is present, the average number of samples (or observations) required  for rrlakitlg a decision is significantly greater than when noise alone is present. The Sequential  Observer makes a relatively prompt decision when only noise is present.  The average savings also depend upon whether detection is performed coherently or  noncoherently. 
  QUAD 
 Multiple Radars. A single doppler radar measures only a single radial component of velocity. Lhermitte3 was among the first to describe how two or more doppler radars could be used, scanning together, to obtain the full three- dimensional air motion fields in precipitation. 
 3.46  Amplitude-Discrimination CFAR (Cell- Averaging CFAR)  ............................................  3.47  Phase-Discrimination CFAR (CPACS)  ...............  3.49 Effect on Range Resolution and Azimuth  Accuracy  ......................................................... 
 7.6] THE U.S. TACTICAL AIR COMMANDS 233 10enemy planes downed. After this initial shakedown period, 90enemy planes were destroyed foraloss of13totheRAF, before enemy jamming ofthe1.5-m equipment used inthis first work put anend toitsusefulness. 
 Seaclutterisnotasstronganddoesnotusuallyextendtoasgreat arangeasdoeslandclutter.Thushigh-flying aircraftovertheseacanbedetected atlongrange withrelatively conventional radarwithonlyaminimal MTI,orevenwithnoMTIinsome cases.Amoresevereproblem occurs'when aseaborne radarmustoperatenearland.Land cluttercanbesolargethatclutterechoesmightentertheradarreceiver viatheantenn.t. sidelobes. In this case, when strong land clutter is a problem, a good MTI or pulse-doppler  radar is required. 
 PULSE DOPPLER RADAR  4.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 However, some pulse doppler radars employ a PRF that is unambiguous in veloc - ity magnitude only, i.e., fR,min = 2 [max( VT,max,closing , VT,max,opening ) + Vg] / l, and rely on  detections in multiple PRFs during the time on target to resolve the sign ambiguity in  doppler. These radars can be described as high-medium -PRF and can be considered  to be in the high-PRF category if the older definition of high PRF (no velocity ambi - guity) is extended to allow one velocity ambiguity, that of doppler sense. The lower  PRF eases the measurement of true range while retaining the high-PRF advantage of  a single blind-speed region near zero doppler. 
 (2.40) ], and a class  of pdf's called the" K-distributions" based on modeling the clutter as a finite two-dimensional  random walk.29 The Weibull pdf has also been examined for modeling sea clutter.14• 15 It is a  two-parameter pdf, like the log normal, but is intermediate between the Rayleigh and the  log normal. In the Weibull clutter model the amplitude probability density function of the  voltage v out of the envelope detector is  (V)a-1 [ (l')a] p(v) = ex In 2 ~,: exp -In 2 vm (13.12)  .)  where ex is a parameter that relates to the skewness of the distribution (sometimes called the  Weibull parameter), and vm is the median value of the distribution. By appropriately adjusting  its parameters, the Weibull can be made to approach either the Rayleigh or the log-normal  distributions. 
 It is supposed that it will further improve the quality of the ISAR image. Based on the sparsity of the ISAR signal due to the limited number of frequency channels in which the ISAR signal is registered, a compressed sensing approach, as l0and l1norm minimization, can be applied in restoring the pulsar signal structure and ISAR image reconstruction. Future research works will be focused on other properties and applications of pulsar emissions in the area of stellar navigation and early warning systems for asteroid detection and imaging. 
 QUENCIES GENERATED BY A $$3 CAN BE READILY PREDICTED AS THEY ARE A FUNCTION OF THE  DIGITAL ARCHITECTURE AND PROGRAMMED FREQUENCY 4HE SPURIOUS SIGNAL MAGNITUDES ARE LESS PREDICTABLE AS THE MAGNITUDES OF THE DOMINANT SPURIOUS SIGNALS ARE A FUNCTION OF THE $! CONVERTER NONLINEARITY 7HEN GENERATING #7 WAVEFORMS  THE $! CONVERTER SEQUENCE REPEATS AFTER  +  SAMPLES WHERE + EQUALS THE GREATEST COMMON DIVISOR OF .E AND -F  4HUS  SPURIOUS  SIGNALS OCCUR ONLY AT FREQUENCIES    FNF +SPURCLK    N          )N THE EXTREME CASE WHERE  -F DOES NOT CONTAIN THE FACTOR   THIS CREATES A SPURIOUS FRE 
 ÓÓ°ÎÓ  2!$!2 (!.$"//+  )N   THE 5+ FAVORED OPERATION AT  '(Z  PRESUMABLY AS IT MORE AFFORDABLY  MET THE 5+ PERCEIVED AZIMUTH REQUIREMENTS OF  RESOLUTION AND  ACCURACY 4HE  5NITED 3TATES IDENTIFIED OPERATIONAL PROBLEMS AT  '(Z THAT COULD BE EXPERIENCED IN THE EXTREME RAINFALL CONDITIONS FOUND ON THE 53 EASTERN SEABOARD 4HESE CAUSED hBLACKOUTSv ON EARLY  '(Z SYSTEMSDEFINED AS AN EFFECTIVE RANGE OF LESS THAN  MILE !S A CONSEQUENCE  THE 53 FAVORED OPERATION AT  '(Z 4HE SHORTEST PULSE LENGTHS THEN COMMONLY AVAILABLE AROUND  NS  MADE THE CLUTTER CELLS LARGE  RESULTING IN  '(Z RADARS BEING VERY SUSCEPTIBLE TO RAIN CLUTTER  PARTICULARLY AS CLUTTER PROCESSING TECHNIQUES WERE IN THEIR INFANCY )N   THERE WAS NO QUESTION THAT A COMMERCIAL SHIP COULD AFFORD BOTH A  AND A   '(Z RADAR  AS THE EXPENSE OF EVEN A SINGLE RADAR SYSTEM  WAS SEEN TO BE A LIMITING ISSUE "ECAUSE OF COST  IT WAS ALREAD Y ENVISAGED THAT FITMENT  WOULD BE CONFINED MAINLY TO CERTAIN CLASSES OF PASSENGER SHIPS THAT HAD A DEFINITE NEED TO CARRY RADAR  PARTICULARLY THOSE WORKING IN THE NORTH !TLANTIC  IN CONGESTED AREAS OR AREAS SUBJECT TO FOG OR ICE 4HE EARLY TRIALS IN THE 5+ CONCENTRATED ON A SINGLE  '(Z DEMONSTRATION SYSTEM  FITTED TO A NAVAL VESSEL )T WAS BASED AROUND A  K7 MAGNETRON CAPABLE OF  NS PULSES AT A 02& OF   (Z )T WAS INTERESTING THAT THE SPEED OF ROTATION COULD BE VAR 
 BAND INTERFERENCE BEFORE IT CAN CAUSE INTERMODULATION OR CROSS 
 Timmoneri, and A. Farina, “Implementation of the recursive QR  algorithm on a 2*2 CORDIC test-board: a case study for radar application,” Proc. of the 25 th  European Microwave Conf ., Bologna (Italy), September 4–7, 1995, pp. 
 THROW  30$4  SWITCHES TO SELECT ONE OUT OF  - BEAMS 4HE BEAMS ARE STATIONARY IN SPACE  AND OVERLAP AT APPROXIMATELY THE  D" POINTS 4HIS IS IN CONTRAST TO THE PREVIOUSLY DISCUSSED METHODS OF SCANNING  WHERE THE BEAM CAN BE STEERED ACCURATELY TO ANY POSI 
 Wong, “Characteristics of a tapered anechoic chamber,”  IEEE Trans ., vol. AP-15, pp. 488–490, May 1967. 
 E. Uhlcnbeck (eds.): "Threshold Signals," MIT Radiation Laboratory Series,  vol. 24, McGraw-Hill Book Company, New York, 1950, p. 
 For large cells it appears distributed in range and may be characterized by a surface- averaged cross section with relatively modest fluctuations about a mean value. As the size of the resolution cell is reduced, clutter takes on the appearance of isolated targetlike, or discrete, returns that vary in time. At these higher resolu- tions, the distributed clutter is often seen to consist of a dense sequence of dis- crete returns. 
 All such algorithms, which perform equally in terms of focused image quality [ 5], require precise geometric acquisition parameters and radiometric parameters. Such parameters are always available as a side documentation of each acquired image. Figure 1reports the acquisition geometry of a SAR system. 
       
 The SNR will decrease to 9.03 dB when h=100 m, which means that the imaging result is seriously defocused. 142. Sensors 2019 ,19, 2921 According to the authors of [ 24], the root mean square error σpsof the phase error due to the decrease of the SNR can be expressed as: σps=1√ 2NL·⎭radicalbig 1−ρ2 ρ(32) where NLstands for the number of looks. 
  
 ING LOBES AS THE ARRAY IS SCANNED )N ADDITION  THE PATTERN IN IMAGINARY SPACE REPRESENTS STORED ENERGY AND CONTRIBUTES TO THE ELEMENT IMPEDANCE IN THE ARRAY 4HE MOST COMMON ELEMENT LATTICES HAVE EITHER A RECTANGULAR OR A TRIANGULAR GRID  !S SHOWN IN &IGURE   THE  MNTH ELEMENT IS LOCATED AT  MD X  NDY  4HE TRIANGULAR GRID  MAY BE THOUGHT OF AS A RECTANGULAR GRID WHERE EVERY OTHER ELEMENT HAS BEEN OMITTED 4HE ELEMENT LOCATIONS CAN BE DEFINED BY REQUIRING THAT M   N BE EVEN #ALCULATIONS FOR THE ELEMENT 
 Consequently, they are modeled on a case-by-case basis. Bistatic Scattering Coefficient.  Values of the scattering coefficient σB0 vary as a  function of the surface composition, frequency, and geometry and are obtained through  field measurement programs. 
 Jr.: Conopi~lsc Radar. IEEE Troru. vol. 
 This front surface contains the  isolation errors Iξη, which arise due to the over -coupling between the receiving and sending  channels, as well as reflections from the environment.  The transmitting and receiving paths  (Tξη & Rξη) are on the side surfaces of the cube and respectively represent the transmitting  and receiving planes.  The edges describe the desired direct co -polarization signal paths. 
 LEVEL ACCURACY CAN BE ACHIEVED  AS SUMMARIZED IN 3ECTION  #OMMENTS ON (ARDWARE   /N A POPULAR !MERICAN CHILDRENS TELEVISION PRO 
 The power supply function is performedbyvarioustypesofpowersuppliesdistributedamongthecircuitcomponentsof a radar set. In ﬁgure 1.14 the modulator, transmitter, and receiver are contained in the same chassis. In this arrangement, the group of components is called aTRANSCEIVER. 
 The usefulness of the phase definition is most clearly e x- plained by the example of the monostatic measurement.  Thereby merge the two reference  planes.  The measurement of a metallic sphere with radius R0 results in a phase shift of ϕ=(ϕ s- ϕi)=180° at the sphere forefront. 
 OF 
 Robinson, “Predictive decomposition of time series with application to seismic explora - tion,” Geophysics , vol. 32, pp. 418–484, 1967. 
 ", -Ê",ÊÊ, , 4HE FACTORS THAT GOVERN THE CHOICE OF WAVEFORM IN (& RADAR SYSTEMS CAN BE GROUPED INTO TWO CLASSES &IRST  THERE ARE THE CONSIDERATIONS COMMON TO MICROWAVE RADAR  THAT IS  RANGE AND DOPPLER RESOLUTION AS DESCRIBED BY THE AMBIGUITY FUNCTION AND OPTIMIZED . 
 6.15.—Polar diagram oftypical CHstation forreliable pickup ofsingle fighter aircraft along thelineofsight. Solid linerepresents main arrays; broken linerepresents gap-filling arrays. logical conditions. 
 Ward, “Frequency management support for remote sea-state sensing  using the JINDALEE skywave radar,” IEEE J. of Oceanic Engr ., vol. OE-11, pp. 
 deviating from a straight line. These deviations must be sensed and proper compensation  applied to the received-signal phase so as to "straighten out" the synthetic antenna.I9 The  required phase correction is a function of range with the Inore rapid corrections required at  steep depression angles. Thus both motion compensation and antenna stabilization are neces-  sary to achieve the resolution inherent in an SAR. 
 BEAM ANA 
 Onehypothesis isthatthereceiveroutputisdueto noisealone;theotheristhattheoutputisduetosignal-plus-noise. Itwasshown.in Chap.2 thatthedividing linebetween thesetworegionsdepended upontheprobability ofafalse alarm,whichinturnisrelatedtotheaveragetimebetween falsealarms. Therearetwotypesoferrorsthatmightbemadeinthedecision process. 
  
 1499–1510, 1995. 41. R. 
 Examples ofthetheoretical bistaticcrosssectionofasphereareshowninFig.14.13. Comparison ofbistaticandmonostatic radars.Itisdifficult tomakeaprecisecomparison of bistaticandmonostatic radarsbecauseofthedissimilarity intheirgeometries. Thecoverage of amonostatic radarisbasically hemispherical, whilethebistaticradarcoverage ismoreorless planar.Themonostatic radaristhemoreversatile ofthetwobecauseofitsabilitytoscan ahemispherical volume inspaceandbecause oftherelativeeasewithwhichusabletarget information canbeextracted fromthereceived signal.Another advantage ofmonostatic radar isthatonlyonesiteisrequired ascompared withthetwositesofthebistaticradar.Thusa bistatic-radar systemmightbemoreexpensive thanamonostatic radarofcomparable detec­ tionabilitysincethecostofdeveloping theadditional site(building roads,sleeping quarters. 
 Two tone intermodulation distortion  is also important in receiver applications. Testing is performed with two sinusoidal input  signals of unequal frequency and levels set such that the sum of the two inputs does  not exceed the A/D converter full-scale level. Similar to IMD for amplifiers, the most  significant distortion is usually second order or third order IMD products. 
 18. Steinberg, B. D.: "Microwave Imaging with Large Antenna Arrays," John Wiley & Sons, New York, 1983. 
 Thedistributed natureofthearraymeansthatitcanfailgradually ratherthanallatonce(catastrophically). Cortl'e,Jient aperwre shape.Theshapeofthearraypermits flushmounting anditcanbe hardened toresistblast.. 336 INTRODUCTION TO RADAR SYSTEMS  Elrctronic beam stabilization. 
 Probably the first of these was an airborne system built by  NASA’s Jet Propulsion Laboratory. The first one in space was the Shuttle Imaging  Radar–C (SIR-C). Although use of multiple polarizations dates from the early days of  imaging radars, the measurement of phase between the received signal with different  polarizations is more recent, dating from the late 1980s. 
 Sensors 2019 ,19, 252 To avoid grating lobes in the MIMO array factor, it is necessary that FTXhas a null in correspondence of every grating lobe of FRXand vice versa. In Figure 1is shown an example of a typical MIMO array factor resulting from the product of a transmitting and receiving array factors, it can be noticed that all the grating lobes inside the receiving array factor are compensated by the nulls of the transmitting one. Figure 1. 
 Holt. F. S.. 
 For instance, by applying spectrum analysis techniques, it is pos - sible to extract accurate sea-state information, including significant wave height and  period, direction, and speed.16 The Miros A/S WavexTM system determines directional  wave spectra scaled in m2/Hz and parameters such as significant wave height and  average wave period. An FFT is performed on data collected on a scan-by-scan basis;  32 scans of data are typically used in the analysis. The resultant information can be  highly useful for large high-speed craft, perhaps traveling at up to 60 knots or more. 
 Ahearn, S. R. Curley, J. 
 PACITATE A SKYWAVE RADAR FOR A PERIOD FROM MINUTES TO HOURS 0ERHAPS MORE IMPORTANTLY   ALTHOUGH THE FLARE ITSELF IS NOT PREDICTABLE  THE ASSOCIATED BURST OF PARTICLES WILL START TO  ARRIVE A FEW HOURS LATER  WITH MOST EJECTED MATERIAL REACHING %ARTH SEVERAL DAYS LATER  SERIOUSLY DISRUPTING (& PROPAGATION 4HE CRITICAL IMPORTANCE OF SOLAR ACTIVITY WILL BE DEMONSTRATED IN 3ECTION  IN THE CONTEXT OF RADAR PERFORMANCE PREDICTION )ONOSPHERIC $YNAMICS  !S THE RADAR SIGNALS TRAVERSE THE IONOSPHERE  MOTIONS OF THE  PLASMA MEDIUM ALONG THE PROPAGATION PATH IMPRINT THEMSELVES ON THE SIGNALS IN WAYS THAT CAN DEGRADE OR OBLITERATE THE TARGET INFORMATION OF INTEREST 3KYWAVE RADARS CAN BE DESIGNED TO RECOGNIZE THE SIGNATURES OF THESE PHENOMENA  ADJUSTING THE RADAR FREQUENCY  CHOICE OF WAVEFORM  AND PROCESSING TO MITIGATE THEIR EFFECTS WHERE NECESSARY 3OMETIMES THE IONOSPHERIC MOTIONS ACTUALLY HELP THE RADAR  FOR EXAMPLE  B Y ENABLING IT TO DISCRIMI 
 If V7 /t/tl/2 is increased to reduce the probability of a false alarm,  the probability of detection will be reduced also.  Equation (2.29) may be used to plot a family of curves relating the probability of detection  to the threshold voltage and to the amplitude of the sine-wave signal. Although the receiver  designer prefers to operate with voltages, it is more convenient for the radar system engineer to  employ power relationships. 
 This leads to the possibility of modulating the tube  without the need for a high-power modulator as required with cathode pulsing. Such opera-  tion is possible with the forward-wave CFA using a cold secondary-emission cathode. The d-c  operating voltage is applied continuously between cathode and anode. 
 #7  RADAR   BUT THE TRANSMISSION  REMAINS PULSED 3UPPOSE THE DWELL TIME IS DIVIDED INTO TWO LOOKS )N THE FIRST LOOK  NO &- IS APPLIED   AND THE DOPPLER SHIFT OF THE TARGET IS MEASURED )N THE SECOND LOOK  THE TRANSMITTER FREQUENCY IS VARIED LINEARLY AT A RATEFIN ONE DIRECTION IE  INCREASING OR DECREASING  IN FREQUENCY  $URING THE ROUNDTRIP TIME TO THE TARGET  THE LOCAL OSCILLATOR HAS CHANGED FREQUENCY SO THE TARGET RETURN HAS A FREQUENCY SHIFT  IN ADDITION TO THE DOPPLER SHIFT  THAT IS PROPORTIONAL TO RANGE 4HE DIFFERENCE IN THE FREQUENCY  $F OF THE TARGET RETURN BETWEEN  THE TWO LOOKS IS FOUND  AND THE TARGET RANGE CALCULATED FROM   2CF F $     4HE  PROBLEM WITH ONLY TWO &- SEGMENTS DURING A DWELL IS THAT  WITH MORE THAN A  SINGLE TARGET IN THE ANTENNA BEAMWIDTH  RANGE GHOSTS RESULT &OR EXAMPLE  WITH TWO TAR 
 R-scope. An A-scope with a segment of the time base expanded near the blip for greater accuracy in  distanq measurement.  RNI, or Range-Height Indicator. 
 CLUTTER RATIO IN  AN /4( RADAR RECEIVER MAY BE AS LOW AS n D" FOR SYSTEMS EMPLOYING &- 
 5. pp. 4 7 49. 
 The radar settransmits apulse ofduration ?,which travels from theairplane toward thetarget atthevelocity c.Aparticu- larscatterer will beilluminated foratime equal tothe pulse length, asthe advancing pulse goes by, and will send areflected pulse ofthe same duration back tothe receiver. The signal received atatime t, measured from the moment the transmitter begins toradiate itspulse, will consist ofcontributions from allthose scatterers Which liewithin theantenna beamwidth aand within arange interval AR, where R’–AR =~c(t–r), (27) R{=~ct. inthkguide isgreater than thefree-space wavelength (Sec. 
 PLANE SPACING 4HE SEVEN OUTPUTS WERE COMBINED BY USING A SINGLE  AIR STRIPLINE COMBINER WITH  
 Milne. K.: The Combination of Pulse Compression with Frequency Scanning for Three-Dimensional  Radars, Radio and Electronic Engineer, vol. 28, pp. 
 VARYING PHASE ERRORS AS PART OF THE IMAGE FORMATION PROCESS 4HE RESULT ALLOWED AN INCREASE IN COHERENT INTEGRATION TIMES COMPARABLE TO MONOSTATIC 3!2  TYPICALLY    SECONDS  #ONSEQUENTLY  BISTATIC 3!2 IMAGE QUALITY WAS GREATLY IMPROVED  AS REPORTED BY "  2IGLING IN #HAPTER  OF 7ILLIS AND 'RIFFITHS  "ISTATIC SPACE 
 In the previous  paragraph, the proliferation of ESA antennas in modern radar systems is linked to the Chapter 12 ch12.indd   1 12/17/07   2:30:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 
 5. Greenwood, I. A., Jr., J. 
 The more important ofthese limitations arementioned below. The outstanding requirement isforlow total weight. Every part ofthedesign isinfluenced bythe necessity formaking the final weight oftheradar assmall aspossible. 
 # -ARCHAIS  AND % .ORMANT   !IR AND 3PACEBORNE 2ADAR  3YSTEMS !N )NTRODUCTION  .ORWICH  .9 7ILLIAM !NDREW 0UBLISHING    PP n  n  n    * $AVIS  h3UN INTROS EIGHTnCORE PROCESSOR v  %LECTRONIC .EWS  2EED %LSEVIER  .OVEMBER     !LTERA #ORPORATION  h3TRATIX )) &0'!S v .OVEMBER   HTTPWWWALTERACOM  $ ! &ULGHUM  h$EEP LOOK v !VIATION 7EEK AND 3PACE 4ECHNOLOGY   *ANUARY     $ ! &ULGHUM  h&UTURE RADAR v  !VIATION 7EEK AND 3PACE 4ECHNOLOGY   /CTOBER     - 0ECK AND ' 7 'OODMAN  *R  h!GILE RADAR BEAMS v  #)32 *OURNAL  PP n  -AY   h2AYTHEONS !0' 
 These grating lobes can cause ambiguities in the measurement. The ambiguities can  be resolved by use of more than two antennas with unequal spacings. The outer two antennas  provide accurate. 
 7.l.3 The main lobe is at zero degrees. The first irregularity in this particular radiation  pattern is the vestigial lobe, or" shoulder," on the side of the main beam. The vestigial lobe  does not always appear in antenna radiation patterns. 
 A specific point target appears to have a LOS  velocity of Ωr relative to the SAR, where r is the crossrange distance of the target  from the LOS. These apparent LOS velocities will result in doppler frequencies (in  absolute value) of 2 v(apparent)/  l = 2Ωr/l, where l is the wavelength corresponding  to the carrier frequency. For each range bin, we now have N complex numbers corresponding to different  radar echoes in the time domain. 
 CABLE TO ANY TARGET  INCLUDING LAND TARGETS OF COMPLEX SHAPE THAT ARE LARGE WITH RESPECT  TO A WAVELENGTH 4HE MAJOR DIFFERENCE IS IN THE TARGET MOTION  BUT THE DISCUSSIONS ARE SUFFICIENTLY GENERAL TO APPLY TO ANY TARGET SITUATION 4HE ECHO RETURN FROM A COMPLEX TARGET DIFFERS FROM THAT OF A POINT SOURCE BY THE  MODULATIONS THAT ARE PRODUCED BY THE CHANGE IN AMPLITUDE AND RELATIVE PHASE OF THE RETURNS FROM THE INDIVIDUAL ELEMENTS 4HE WORD  MODULATIONS IS USED IN PLURAL FORM  BECAUSE FIVE TYPES OF MODULATION OF THE ECHO SIGNAL THAT ARE CAUSED BY A COMPLEX TARGET AFFECT RADARS 4HESE ARE AMPLITUDE MODULATION  PHASE FRONT MODULATION GLINT   POLAR 
 Pulse compression offers some  ECCM advantage that is discussed hereafter.3,148 When the pulse compression search  radar is compared, from an ESM standpoint, with a conventional search radar with  the same wide pulse, the enemy receiver on a jamming platform will not know (in  the general case) the pulse compression reference code and will be at a disadvantage.   Compared with a radar that uses an uncompressed wide pulse, the pulse compression  technique increases the radar’s capability against extended signal returns like chaff  and clutter. In addition, noise from a jammer does not pulse-compress. 
 Cho et al., “Range-velocity ambiguity mitigation schemes for the enhanced terminal doppler  weather radar,” in 31st Conference on Radar Meteorology , Seattle, W A, 2003, pp. 463–466. 53. 
 The width of the compressed pulse at the half-amplitude point is nominally equal to  the subpulse width. The range resolution is hence proportional to the time duration of  one element of the code (one subpulse). The time-bandwidth product and pulse com - pression ratio are equal to the number of subpulses in the waveform; i.e., the number  of elements in the code. 
 The insertion loss increases for successive radia - tors, and the tolerances required for setting the phases are high. This type is not  commonly used. Parallel Feeds. 
 CADED AMPLIFIER STAGES AS WELL AS PARALLEL ISOLATION &OR EXAMPLE  WHEN A #LASS 
 Thus, Mitzner's ex- pression for the scattered field contains only the contributions from the filamen- tary edge currents. In applying his theory to scattering objects, therefore, the contributions of nonfilamentary induced surface currents must be accounted for separately, just as in Ufimtsev's physical theory of diffraction. When the direc- tions of incidence and scattering become perpendicular to an edge, the perpendicular-parallel terms disappear and Mitzner's diffraction coefficients then reduce identically to Ufimtsev's. 
 AIR SIGNALS FOR  PASSIVE COHERENT LOCATION v %LECTRONICS ,ETTERS  VOL   NO   *UNE     - ! 2INGER AND ' * 'LAZER  h7AVEFORM ANALYSIS OF TRANSMISSIONS OF OPPORTUNITY FOR PASSIVE  RADAR v IN  &IFTH )NTERNATIONAL 3YMPOSIUM ON 3IGNAL 0ROCESSING AND ITS !PPLICATIONS  "RISBANE   !USTRALIA  !UGUST   PP n  2ICHARD ,ODWIG  PRIVATE COMMUNICATION  ,OCKHEED -ARTIN -ISSION 3YSTEMS   ( $ 'RIFFITHS AND # * "AKER  h0ASSIVE COHERENT LOCATION RADAR SYSTEMS 0ART  0ERFORMANCE  PREDICTION v )%% 0ROC 
 WAY RADAR RECEIVERS  WHICH NECESSARILY MUST WORK MUCH FARTHER INTO THE RECEIVER NOISE  4HE SEVERITY OF THIS PROBLEM WAS QUANTIFIED BY IN SITU MEASUREMENTS OF SEVERAL  6(& AND 5(& BANDS IN A DENSE URBAN ENVIRONMENT !MBIENT 6(& NOISE LEVELS  WERE FOUND TO BE TYPICALLY  D" GREATER THAN THERMAL NOISE AND DIRECT PATH ILLUMINATOR SIGNALS SOME  D" GREATER STILL %VEN WITH ROBUST CANCELLATION TECHNIQUES  THE RESIDUE OF THIS UNSUPPRESSED 2&) WILL INCREASE THE 0"2S SYSTEM NOISE FIGURE BY MANY TENS OF DECIBELS A  D" NOISE FIGURE AT 6(& IN URBAN AND SEMI 
 September, 1966.  120. Weigand. 
 Furthermore, it is difficult to know the polarization,  and the exact size and shape of the common area illuminated by the antenna beams  are sometimes difficult to determine. For this reason, few bistatic measurements from  aircraft have been reported in the literature.107 Laboratory bistatic measurements have been made by both the Waterways  Experiment Station42 and The Ohio State University2,6 groups using electromagnetic  waves and by the University of Kansas100 group using acoustic waves. Bistatic mea - surements of laser radiation have been made at Bell Telephone Laboratories,108 and  C-band measurements of buildings have been made at the University of Kansas.109  Other surface-based measurements have also been reported.110,111 Bistatic measurements call for complications when made outside the laboratory  because an absolute reference for both transmitter power and receiver sensitivity must  be used. 
 If this were a parallel feed it would be  called a pcirailel-pa,.allel.f>ed. (Series feeds are shown here so as not to overly complicate the  figure. Series-pnrallel or series-sereirs arrangements are also possible.) All the elements which  lie in the same colurnn utilize the same phase shift to steer the beam in azimuth. 
 Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar.  PULSE DOPPLER RADAR  4.396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 of the target provided by the tracker, a single PRF can be chosen such that range and  doppler eclipsing is avoided with high probability. The length of the dwell is adapted  to provide sufficient energy on target so that its return signal-to-noise ratio will pro - vide the necessary measurement accuracies required by the tracker. 
                 &)'52%  $IURNAL VARIATION OF THE ELECTRON DENSITY PROFILE  AS MEASURED BY THE PLASMA FREQUENCY   PLOTTED FOR VARIOUS VIRTUAL HEIGHTS IN KM  4HE DATA WAS RECORDED BY A VERTICAL INCIDENCE SOUNDER AT  LATITUDE  3  LONGITUDE  % ON  3EPTEMBER   33.    &)'52%   #OMPARISON OF MEASURED VERTICAL INCIDENCE IONOGRAMS  FOR A FIXED TIME OF DAY OVER A MONTH WITH A MODEL 
 (ILL    #HAP   7EHNER   (IGH 2ESOLUTION 2ADAR  #HAP   'ALATI   !DVANCED 2ADAR 4ECHNIQUES AND 3YSTEMS  )%% 2ADAR 3ONAR .AVIGATION AND !VIONICS  3ERIES 6OL  ,ONDON )%% "OOKS    P   !STANIN AND +OSTYLEV   5LTRA 
 ch01.indd   7 11/30/07   4:33:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 
 TANEOUS BANDWIDTH THAN DOES A CONVENTIONAL KLYSTRON  4HE LOWER VOLTAGES AT WHICH  THEY OPERATE RESULT IN POWER SUPPLIES THAT CAN BE SIMPLER  LIGHTER  CHEAPER  AND MORE RELIABLE 4HE -"+ CAN HAVE A HIGH OUTPUT 
 1630- 1635, Septemhor, 1960.  68. C'rispin, J. 
 Remote Sens. Lett. 2008 ,5, 760–763. 
 Zeger, A. E., and L. R. 
 Klauder, J.R.; Price, A.C.; Darlington, S.; Albersheim, W.J. The Theory and Design of Chirp Radars. Bell Syst. 
         
 Measuring the time delay between the two sets of coincidence pulses yields the true target range. If desired, a three- PRF system can be mechanized similarly. The advantage obtained is the in- creased unambiguous range achievable. 
 Range tracking usually provides  the major means for discriminating the desired target from other targets (although  doppler frequency and angle discrimination are also used) by performing range gat - ing (time gating) to eliminate the echo of other targets at different ranges from the  error-detector outputs. The range-tracking circuitry is also used for acquiring a desired  target. Range tracking requires not only that the time of travel of the pulse to and from  the target be measured but also that the return is identified as a target rather than noise  and a range-time history of the target be maintained. 
 Survey on Unsupervised Change Detection Techniques in SAR Images1. In Proceedings of the 2014 IEEE China Summit International Conference on Signal and Information Processing (ChinaSIP), Xi’an, China, 9–13 July 2014; pp. 143–147. 
 In practice, stagger tuning enables the bandwidth  of the multicavity klystron amplifier to be increased from a synchronously tuned bandwidth of  4 to percent to values of more than 5 percent. Multicavity klystrons can be designed with  bandwidths as large as 10 to 12 percent or greater.7.10.41*50  Tuning. Altllough conventional kiystrorls are of narrow bandwidth, they may be tuned over a  wide frequency range.' A simple tuning mechanism is a flexible wall in the resonant cavity. 
 SENSITIVITY 4YPICALLY  A SINGLE CONSTANT VALUE IS SPECIFIED )N  PRACTICE  THE SENSITIVITY VARIES SIGNIFICANTLY WITH VIBRATION FREQUENCY AND IS DIFFERENT FOR EACH AXIS %QUATION  CAN BE USED TO DETERMINE THE EFFECT ON OSCILLATOR PHASE NOISE DUE TO RANDOM VIBRATION IN EACH AXIS   ,FFF FVII V V  L O G  § ©¨ ¨¶ ¸· ·'G      D"C 33" IN A  (Z BANDWIDTH     WHERE FV   VIBRATION FREQUENCY (Z   F   OSCILLATOR FREQUENCY (Z   'I   OSCILLATOR FRACTIONAL FREQUENCY VIBRATION SENSITIVITY  G 
 51, p. 1256, September 1963. 25. 
 .. ..... ...108 CHAP. 
 ENCE FRAME AND DISPLAYED APPROPRIATELY #0! AND 4#0! ARE CONTINUALLY CALCULATED  FOR ALL TRACKED TARGETS  SUCH THAT IF LIMITS PRESET BY THE USER ARE BREACHED  AN ALARM 4!",%  2EQUIREMENTS FOR RADAR TRACKED TARGET ACCURACY  LEVELS  #OURTESY OF )-/  4IME OF 3TEADY  3TATE MINUTES 2ELATIVE  #OURSE  DEGREES 2ELATIVE  3PEED KN  #0! .- 4#0!  MINUTES 4RUE  #OURSE  DEGREES 4RUE 3PEED  KN   MIN TREND o  OR   WHICHEVER IS GREATER  
 54. Moffatt, D. L., and R. 
 FORMAT  4%- 
 Other approximations may be devised for nonconducting surfaces; if the incident wavelength is long enough, for example, the surface of a soap bubble or the leaf of a tree may be modeled as a thin membrane, on which neither the electric nor the magnetic fields are zero. The integral is easy to evaluate for flat metallic plates because the phase is the only quantity within the integral that varies, and it varies linearly across the sur- face. The result for a rectangular plate viewed in a principal plane is . 
 WIDTH SHOULD USE A HIGH )& FREQUENCY CENTERED IN ONE OF THESE REGIONS &OR )& FREQUEN 
 The microwave power Si BJT is invariably an NPN structure (Figure 11.3 e) with  a vertical diffusion profile; i.e., the collector contact forms the bottom layer of the  chip. The P-type base region has been diffused or implanted into the collector, the   N-type emitter has been diffused or implanted into the base, and both base and emitter  regions are accessible from the top surface of the chip. The collector region consists  of an N-doped, low-resistivity epitaxial layer that is grown on a very low resistivity  silicon substrate. 
 It has been considered in those  radar applications where it is necessary to shift the beam rapidly from one position in space to  another, or where it is required to obtain information about many targets at a flexible, rapid  data rate. The full potential of a phased-array antenna requires the use of a conlpiltcr that can  determine in real time, on the basis of the actual operational situation, how bcst to ~sc ttlc  capabilities offered by the array.  The concept of directive radiation from fixed (nonsteered) phased-array antennas wah  known during World War I.' The first use of the phased-array antenna in commercial broad-  casting transmission was in the early thirtiesZ and the first large steered directive array for the  reception of transatlantic short-wave communication was developed and installed by the Bell  Telephone Laboratories in the late thirties.' In World War 11, the United States, Great  Britain, and Germany all used radar with fixed phased-array antennas in which the beam  was scanned by mechanically actuated phase shifters. 
 OUS  PERFORMANCE 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç° &)'52%  /PTIMUM VALUES OF  0. AS A FUNCTION OF THE SAMPLE SIZE  N AND THE PROBABILITY OF FALSE  ALARM @ 2ICEAN DISTRIBUTION WITH 3.     D" PER PULSE AFTER ' - $ILLARD Ú )%%%   &)'52%  #OMPARISON OF BINARY INTEGRATOR - 
 B. Rutledge and M. S. 
 Using monopulse measurements to  segregate and bin targets that are distinguishable in angle can also reduce ghosting  when there are a significant number of detections in a dwell. A typical medium- or high-medium-PRF pulse doppler waveform cycles through  N unique PRFs in a processing dwell ( N typically being 5 to 8). The medium PRFs  generally cover nearly an octave in frequency for good doppler visibility and ground  moving target rejection. 
 67. Jao, J. K., and M. 
 26.6 PROPAGATION MODELING2,7 Radio wave modeling is important for a number of reasons, all of which could be  summarized into two large categories of engineering studies and operational perfor - mance. For engineering studies, the effects of propagation may be considered in new  system design or in the evaluation of long-term performance of existing systems. For  operational performance, consideration of propagation effects is usually based upon  a single measured or forecasted atmosphere such that these effects can be exploited  or mitigated by altering the system’s use tactics. 
 The transistor amplifier, and the bulk-effect and avalanche diodes have important appli­ cations in radar; butin the form in which they have been known, it is not likely that they will  cause the high-power microwave tubes to disappear in the way their lower frequency counter­ parts have displaced the receiver vacuum tube.  REFERENCES  J. Weil, Thomas A.: Transmitters, Chap. 
 Also, it is difficult to describe a priori the precise nature of the trajectory disturbances.  Some form of adaptation to maneuvers is required.76 The Kalman filter is sophisticated and  accurate, but is more costly to implement than the several other methods commonly used for  the smoothing and prediction of tracking data.77 Its chief advantage over the classical a-/?  tracker is its intlerent ability to take account of maneuver statistics. If, however, the Kalman  filter were restricted to modeling the target trajectory as a straight line and if the measurement  noise and the trajectory disturbance noise were modeled as white, gaussian noise with zero  mean, the Kalman filter equations reduce to the a-/? filter equations with the parameters a and /I computed sequentially by the Kalman filter procedure. 
 If R,(I), for example, were the rernanent magnetization needed  to produce a phase change of I 80" relative to the rernanent magnetization - B,, the aniplitude  and ~vidth of the driving pulse would be selected so as to rise up to point 1 on the hysteresis  curve. When the current pulse decays to zero, the magnetization falls back to the remanent  valtre /?,(I) along tlie indicated curve. The difference in phase between - B,(l) and the value  !I,( I) tlctcr~iii~ics tlic pliasc iticreriient. 
 192–201, January 2003. 141. D. 
 • Jammer power level estimation . An estimate of the power level can be obtained by  the first-order linear filter initialized from g0(t1j) = 1 for a suitable filter coefficient  aj ∈ (0,1):  γ α γ αρ o j o jt tkj kjkj( )= ⋅ ( )+ − ⋅−11 1 010( )  (24.14) • Adaptation of the detection threshold . For a given detection threshold b  (in dB), the  probability of false alarm turns out to be:  P G Rkjfa stc= − ( ) +   exp ( )/10 110 02β γ Σ (24.15)  Hence, the detection threshold can be selected at each time instant, tk, in the follow - ing way:  β γk kktkj kjG r = −( ) (− max . 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.92  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 transmitter has very little pulse-to-pulse frequency or phase jitter. In addition, the  system must successfully operate in an environment that comprises many unwanted  targets, such as birds, insects, and automobiles. 
  DESIGN PHILOSOPHY ,OW #ROSS 3ECTION 3HIPS  #ONVENTIONAL SHIPS USUALLY HAVE VERY LARGE STRUCTURES  WITH MANY HORIZONTAL AND VERTICAL REFLECTING SURFACES THAT MEET  AT RIGHT ANGLES  FORM 
 TO 
  
 NOISE AMPLIFIER ,.!  IS EITHER A COOLED MASER OR A FIELD EFFECT TRANSISTOR AND MAY BE SWITCHED BETWEEN THE  ANTENNA AND AN AMBIENT LOAD  ALLOWING AMPLITUDE CALIBRATION OF THE INPUT $URING BISTATIC OPERATIONS  A SIGNAL FROM THE LOW 
 EX TRACTION OF INFORMATION AND WAVEFORM DESIGN 423  Figure 11.15 Linear FM pulse com-  C pression. (a) Transmitted waveform;  al 3 (b) frequency of the transmitted u a waveform; (c) representation of the  time waveform; (d) output of the  1 pulse-compression filter; (e) same as *Time  (1 t2 (6) but with decreasing frequency  (el modulation.  the modulated pulse, which is proportional to (sin nBt)/nBt.15 The peak power of the pulse is  increased by the pulse compression ratio BT after passage through the filter. 
 Unfortunately the range ofecho intensities involved issogreat that, ifthe receiver has gain high enough torender the terrain visible, the signals from built-up areas must bedrastically limited toavoid “blooming” ofthe cathode-ray tube, and detail isdestroyed. Ifthe gain islow enough topreserve detail, theland background isnot visible. This difficulty ismade worse bythenonlinear response ofthecathode- raytube. 
 DETECTOR 
 When an element is placed in an array of many elements, the effects of coupling are sufficiently strong that the pattern and impedance of the element in the array are drastically altered. The terms active element pattern and element impedance refer to an element in its operating environment (i.e., in an array with its neighboring elements ex- cited). In the array, each excited element couples to every other element. 
 Theproduct ofthermstime­ delayerror[Eq.(11.17)]andthermsfrequency error[Eq.(11.27)] is 1 (jTR(jf=7i~2E/No) Substituting theinequality ofEq.(11.34)intheabovegives , 1 (j1Rbfs~(2E7No)(11.36) Thisstatesthatthetimedelayandthefrequency maybesimultaneously measured toassmalla theoretical errorasonedesiresbydesigning theradartoyieldasufficiently largeratioofsignal c"era.\'(E)tonoisepowerperhertz(N()),orforfixedE/No,toselectaradarwaveform which resultsinalargevalueofIllX.LargePIXproducts requirewaveforms longinduration andof widebandwidth. Thepoorestwaveform forobtaining accurate time-delay andfrequency measurements simultaneously istheoneforwhichPIX=n.Itmaybeshownthatthiscorresponds tothe gaussian-shaped pulse.Thetriangular-shaped pulseislittlebetter,sinceitsPIXproduct is~n. Theradar"uncertainty" relationseemstohavetheopposite interpretation oftheuncer­ taintyprinciple ofquantum mechanics. 
 A moderate amount of leakage entering the receiver along with the echo  signal supplies the reference necessary for the detection of the doppler frequency shift. If a  leakage signal of sufficient magnitude were not present, a sample of the transmitted signal  would have to be deliberately introduced into the receiver to provide the necessary reference  freqitency.  Tliere are two practical effects which limit the amount of transmitter leakage power which  can be tolerated at the receiver. 
 G éoinf. 2016 ,47, 102–111. [ CrossRef ] 32. 
 BAND SATELLITES  DISTRIBUTED IN THREE   
 50, pp. 15 15-1520, June, 1962.  68. 
 Thus, for a given band - width, increasing the number of looks reduces speckle, but at the cost of compromising  resolution. (More on this trade-off may be found in Section 18.4.) In contrast to conventional post-detection imagery, focused SAR data may be pre - sented as single-look complex (SLC) products. These data retain the full resolution of  the radar, and most important, retain the relative phase of the backscattered field. 
 TION OF THE RELATIVE BACKGROUND POWER LEVEL . 
 AP-25, September 1977. 53. W. 
 Figure 2.20. Pick-up, disappearing and homing ranges on forward aerials (numbers refer to number of disappearing contacts) (redrawn from [ 14]).Airborne Maritime Surveillance Radar, Volume 1 2-21. Further evidence of the introduction of Metox was found from analysis of the total number of U-boat sightings by aircraft with and without ASV, over the periods May to September 1942 and October 1942 to February 1943. 
 The first  is to understand the applicability of GPR to particular soils and hence the possibility  of using GPR to detect buried targets such as pipe, cables, landmines, etc. The second  is to use GPR to characterize soils and soil properties. GPR can provide a detailed map of the subsurface, which when combined with  traditional soil survey methods can provide information on the type of soil, its extent  laterally and in depth, the water table, the layering and features of the soil, and hence  its local geology and history. 
 ARRAYS ! SUB 
 Electromagn. Res. 2008 ,85, 25–37. 
 For exaniple, a 120" torus antenna might be scanned by continuously rotating  three feeds spaced 120" apart on the spokes of a wheel so that one feed is always illuminating  tlic reflector. Altliougli tliis may be practical in small-size antennas, it becomes a difficult  ti~echariical probleni if tlic radius of the rotating arm is large.  Scanning may also be accomplished by arranging a series of feeds on the locus of the focal  points of tile torus and switching the transmitter power from one feed to the next with an  organ-pipe  canner.'*^.'^^ The principle of the organ-pipe scanner is shown in Fig. 
 RANGE DETECTION OF LOW 
 (ILL "OOK #OMPANY    7 & 'ABRIEL  'UEST EDITOR  SPECIAL ISSUE ON ADAPTIVE ANTENNAS   )%%% 4RANS  VOL !0 
 Sletten et al., “Offset dual reflector antennas for very low sidelobes,” Microwave J .,  pp. 221–240, May 1986. 25. 
 GIirtt retluctiort. In a tracking radar, the angle and range errors introduced by a finite size target  are reduced with increased range-resolution since it permits individual scattering centers  to be resolved.  hftrlripatlt resoluriort. 
 The peak cross sections in these records are of the order of 10 m2 and are roughly the same for the two polarizations, which is another characteristic of sea clutter at these angles. In- terestingly, while the same measurements made in "calm" water looked vir- tually identical in every detail, peak cross sections were now only 10 cm2, or 40 dB, less. HORIZONTAL POLARIZATION FIG. 
 ING ANGLE RETURNS DISCUSSED IN 3ECTION  THE TENDENCY OF  R   TO LEVEL OFF FOR GRAZING  ANGLES CLOSE TO  SEE &IGURES  AND   MAY BE ASCRIBED TO THIS MECHANISM &ROM WHAT HAS BEEN SAID THUS FAR  IT CAN BE SEEN THAT STRICT ANALYTICAL SOLUTIONS VIA  THE '"60 APPROACH APPEAR TO RUN INTO DEAD ENDS INTRACTABLE FORMAL EXPRESSIONS IN THE FORM OF %Q   SMALL 
   '2/5.$ %#(/  £È°{Ç 7HEN B     THE POLARIZATION IS LINEAR WITH THE % VECTOR IN THE DIRECTION GIVEN   BY X  7HEN B   on  THE POLARIZATION IS CIRCULAR  WITH   n FOR LEFT 
 ¤ ¦¥³ µ´    &)'52%     3TRETCH PULSE COMPRESSION SYSTEM BLOCK DIAGRAM    !     $  $     $        $    !            
 F. S .. H. 
 The trailing edge of an extent may vary as a function of radar parameters and target size, but the start is set by frequency selection and immediately follows the skip zone. Directly below is a plan view of the coverage area. It shows nine different areas that might be illuminated by a separate transmit beam of 8° width. 
 Historically, these  sequences were generated using n stages of shift registers with selected output taps  used for feedback (see Figure 8.17). When the feedback connections are properly  chosen, the output is a sequence of maximal length, which is the maximum length  of a sequence of 1s and 0s that can be formed before the sequence is repeated. The  length of the maximal sequence is N = 2n − 1, where n is the number of stages in the  shift-register generator. 
 The method ofreception always uses the doppler effect inone form oranother. The simplest arrangement isthat shown inFig. 16.3. 
 Near-vertical radar returns from most targets drop  off rapidly as the angle with the vertical is increased. Thus, the measuring beamwidth  or pulsewidth usually encompasses signals from regions having values for s 0 many  decibels apart. Since the scattering coefficient varies much more rapidly near the verti - cal than at angles beyond 10 or 20° from the vertical, the problem is much more severe  at the vertical. 
 ART AT LEAST IN ACCURACY AND LARGE 
 RANGE POINTS AND THE SAME FOR ALL MINIMUM 
 One significant difference is that the feed energy diverges cylindrically rather than  spherically, and so the feed power density falls off as 1/ r  rather than 1/ r 2. The height of the parabolic cylinder (Figure 12.19 a) must allow for beamwidth,  shaping, and steering of the linear feed array. When the line source steers at angle q  from broadside, the primary beam from the source lies on a conic, and the intercepts  at the upper right and left corners of the reflector are farther up than in the center, as  shown in Figure 12.19 b. 
 The units for ASV Mk. VIB [ 6] that were different from ASV Mk. VIA included: Scanning unit type 68A or type 68B; Indicator, rotation assembly, type 2 or 3 (Leigh Light indicator; type 2 for scanning unit type 68A with ﬂexible drive; type 3 for scanning unit type 68B with magslip drive); Attenuator type 58; Control unit type 492 (attenuator rate control); Transmitter receiver TR3519A (standard installation) or TR 3519B (with AFC); Control unit type 498 (tuning control and AFC, for use with TR 3519B); Receiver R.3585; Ampli ﬁer A3586. 
 ( a) Traditional imaging processing; ( b) imaging processing of proposed approach (mixed Euclidean norm); complex images of channels 1 and 2 (ﬁrst and second layers); interferometric phase images (third layer); ﬁnal 3-D imaging results (last layer). 178. Sensors 2018 ,18, 3750 It can be seen from Figure 20that in the case of only 20% echo data applied, effective imaging on the targets is unable to be achieved with the traditional imaging approach. 
 2014 ,7, 4288–4300. [ CrossRef ] 13. Celik, T. 
 ch18.indd   44 12/19/07   5:15:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 Pearson, “FLAMR signal to noise experiments,” Hughes Aircraft Report No. P74-501,  December 1974, declassified 12/31/1987. 96. 
 The  situation is further complicated by the continuous variation of ionospheric propaga - tion conditions, which must be monitored and used to guide tasking, as when bad  ionospheric “weather” is likely to preclude certain missions. Almost invariably, the sectors and, indeed, the individual DIRs within a sector will  require different carrier frequencies, even for a given range, as the ionosphere may  vary substantially across the full range and azimuth extent of the active coverage.  The defining characteristic of HF skywave radar is that the radar operator must select  frequencies that are optimum for the various tasks and adapt these frequencies to the  ever-changing ionosphere. 
 Actually more than two separate radar sets are involved inthe V-beam system, forboth thevertical and theslant beams arethemselves composite. This, however, has nothing todowith the scanning speed limitation, but isrequired merely toget adequate range and vertical coverage. Itisaconsequence, inother words, ofthe radar equation forfanbeams discussed inSec. 
 Sensors 2019 ,19, 490 which means that the underestimation of L1regularization is avoided. In addition, the support information of different subapertures will be used, which will make the results more accurate. LS-CS-Residual mainly has three steps: initial LS estimation, implementing CS on the residual (CS-Residual) and ﬁnal LS estimate. 
 Radar receiver  design and implementation may not always be an easy task; but in tribute to the receiver  designer, it has seldom been an obstacle preventing the radar systems engineer from eventually  accomplishing the desired objectives.  Although the superregenerative, crystal video, and tuned radio frequency (TRF) receivers  have been employed in radar systems, the superheterodyne has seen almost exalusive applica-  tion because of its good sensitivity, high gain, selectivity, and reliability. No other receiver type  has been competitive to the superheterodyne. 
 ING CHANNEL SO THAT TWO SIGNALS FROM A SINGLE SOURCE ARE AVAILABLE FOR COMPARISON  . 
 Horizontal po- larization is similar. (From Moore, Soofi, and Purduski*2) AVERAGE SCATTERING COEFFICIENT o° (dB) AVERAGE SCATTERING COEFFICIENT a° (dB) Regression lines shown are for entire 20-70° data set, but separately for 1 <f < 8 GHz and 13 f<18GHz. Regression equation: a° (dB) = A + Be + Cf + Dfe Regression lines Interpolated model Regression lines shown are for entire 20-70° data set, but separately for 1 <f < 8 GHz and 13 f<18GHz. 
 These antennas can cover a sector of from 10 to 20 degrees or more, at a ·rate of  10 to 20 scans per second or greater. This is a rapid enough rate to permit essentially contin­ uous observation of the target. A radar which uses such a sector-scanning antenna to track the  path of airborne targets is sometimes called a track-while-scan radar. 
 TYPE MODULATOR  THE SWITCH IN THE ACTIVE 
 This combination can beofuse principally foridentification. Airborne beacons. Beacons have facilitated control ofmilitary aircraft from aship, and have been useful foridentification ofair- craft. 
 Further, the oscillator can bemade tolock thephase ofthe transmitter instead ofvice versa. The various arrangements can therefore beclassified according tfi 1.Whether thetransmitter locks theoscillator orvice versa. 2.Whether thelocking takes place atradio frequency orintermediate frequency. 
   PP n    2 :OUGHI  * "REDOW  AND 2 + -OORE  h%VALUATION AND COMPARISON OF DOMINANT BACKSCATTER 
 It parallels  Taylor's approach to the sum pattern.  7.7 COSECANTSQUARED ANTENNA PAITERN  It was shown in Sec. 2.11 that a search radar with an antenna pattern proportional to csc2tl,  where 8 is the elevation angle, produces a constant echo-signal power for a target ttying at  constant altitude, if certain assumptions are satisfied. 
 Extraction of T arget Scattering Information When the distance between the target and the antenna satisﬁes the near-ﬁeld condition and the baseline of the antennas is much smaller than R0, according to plane spectrum theory [ 29], the distance in Formula (1) can be represented as: Ri(t)=( R0+r0cos(θ0+ωt))cosαicosφ+r0sin(θ0+ωt)cosαisinφ+( R0tanαi−z)sinαi, (25) where, φ=arctan/parenleftBigr0sin(θ0+ωt) R0+r0cos(θ0+ωt)/parenrightBig is the angle between the target and antenna in the plane Oxy. To simplify the expression, the Cartesian coordinates of the target are represented in the cylindrical coordinate system, so Equation (25) can be expressed as: Ri(t)=/radicalBig (R0+r0cos(θ0+ωt))2+( r0sin(θ0+ωt))2cosαi+( R0tanαi−z)sinαi. (26) Then, the echo signal of the scattering point Pcan be represented as: si(t)= giexp/parenleftbigg −j4πfRcosαi+( R0tanαi−z)sinαi c/parenrightbigg , (27) where, R=/radicalBig (R0+r0cos(θ0+ωt))2+( r0sin(θ0+ωt))2. 
 A three-pulse MTI filter using binomial weights has a filter mismatch loss of 0.51 dB. The mismatch loss for the binomial-weighted four-pulse canceler is 0.97 dB. Clutter Visibility Factor (Voc). 
 BASED #-2 TRANSMITTERS !N EXAMPLE OF A SOLID 
 An example of clutter a0 for several broad classes of terrain is shown in Fig. 13.8. Thls  applies to X-band clutter. 
 The recommended sequence was then [ 4]: i. Set the range to position 1 (10/10) and adjust the height tube brilliance. ii. 
 The unknown fields may be found by inverting the resulting  matrix and multiplying the inverted matrix by a column matrix representing the  incident field at each patch. The surface fields are then summed in integrals similar  to Eqs. 14.5 and 14.6 to obtain the scattered field, which then may be inserted in  Eq. 
 The angular r esolution as a distance between two targets depends on the slant -range and can be  calculated with help of the following formula:     2 sin [ ]2AS R m     Figure 12: Dependence of the accuracy of the range   (Source: MIT Lincoln Laboratory)     Figure  13: angular resolution   Θ = antenna beam width (Theta)     SA = angular resolution as a distance between the two targets   R = slant range aims - antenna  . Radartutorial (www.radartutorial.eu)   10 Range Resolution   Range resolution is the ability of a radar system to distinguish between two or  more targets on the  same bearing but at different ranges. The degree of range resolution depends on the width of the  transmitted pulse, the types and sizes of targets, and the efficiency of the receiver and indicator. 
 MINATED TARGETS THAT DEGRADES THE CROSS 
 7.2] AIDS TO INDIVIDUAL NAVIGATION 217 marker. Once this index has been setonaradar echo bymeans of adjusting knobs provided onthe device, the index will move across the face ofthe tube with theecho, provided that the wind setting has been made properly, regardless ofmaneuvers oftheaircraft. Asimplified schematic diagram ofthe GPI isshown inFig. 
 An inherent characteristic of airborne pulse doppler radars  is that echoes from large, resolvable objects on the ground (discretes), such as build - ings, may be received through the antenna sidelobes and appear as though they were  ch04.indd   18 12/20/07   4:52:39 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 Changing therelative timephasebetween thesampling pulsetrainandthearrayoutputresultsinobserving a different angular direction. Thusthebeamcanbesteeredbyvarying thetimephaseofthe HOlldp055 fdlp, BW"NIsMulflple~erI------ lcr';i1,-.'s ~(, :;h(-,7+---,(,----+---r--1 ~:N-l ClI,+Tis -I, ·0·'---------,-t---' '---------' I Reomwidth control'1(5 t I I Rpom steeringN-lY1,-2Is .~ Figure8.29Within-pulse scanning usingrrequency-multiplexed lineararray.Thisimplementation has beencalledMOSAR. (From J()ll1l.~o,,'Uj Courtesy Proc.1EEE.). 
  DID  .ORTHROP DID NOT INSTALL EGG 
 Monica, 58  ‘Mountain Goat,’ 132  ‘Mouse’ station, 152  Multi-vibrator, 90 et seg.  Nature, 17, 128  Normandie, the, short-wave  experiments in, I9  Numans oscillator, 94  OBOE, 150 et seq.  Oliphant, Professor M. 
 Keep in mind that the operating frequency  of the radar, along with its required range and radial velocity coverage, determines  whether a PRF is considered medium, high-medium, or high. Also, modern multi - function radars are typically capable of utilizing waveforms from the various PRF  categories in order to carry out their diverse missions. Pulse Doppler Spectrum. 
  '(Z MICROWAVE SCATTEROMETER v IN  0ROC )%%%-44 
  
 This section will discuss oscillators that receive ani-flocking pulse and deliver ani-freference signal according tothearrangement ofFig. 16.9. TheLocking Pulse.—If the phase-locking istobeconstant from one pulse tothenext with aprecision of1°,thecarrier-frequent ypacket that does thelocking must beunusually free ofrandom components. 
 J. W.: Millimeter Wave Research: Past, Present, and Future, h117' Lirrcolrr Ltrh. 'l'cc.11. 
 12. G. B. 
 Initial recognition ofthetarget signal isaccomplished ontheother display, and theproper range setting fortheC-scope display interval isdetermined either byinspection orby displaying onthe search tube anelectronic marker derived from the C-scope brightening signal. The V-beam height indicator isanexample ofthetype ofdisplay con- sidered inthis section, but itsdescription isdeferred toSec. 6.12. 
 UNIT VERSUS  HEIGHT DISPLAY WILL SHOW A CHANGE IN SLOPE  FROM POSITIVE INCREASING  - 
 VIDED A  
 Internal and external busses connect the individual  processing arrays to each other as well as to the other suites, sensors, controls, and  displays. Usually, there are both parallel electrical signal busses as well as serial fiber  optic busses depending on speed and total length in the aircraft.2 The signal and data   processor complex contains multiple processor and memory entities, which might be FIGURE 5.5  MFAR processing ( adapted 2 ) ch05.indd   5 12/17/07   1:26:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 LEM FOR (&372 SYSTEMS !CCORDINGLY  ANTENNAS SHOULD BE DESIGNED WITH LOW GAIN AT HIGHER ELEVATION ANGLES 4HE MAIN DESIGN PARAMETERS OF A REPRESENTATIVE (&372 SYSTEMTHE $ARONMONT  3%#!2 RADARARE LISTED IN 4ABLE  4HE CORRESPONDING VALUES FOR SKYWAVE RADARS CAN BE FOUND IN 4ABLE   0ROPAGATION #ONSIDERATIONS IN (&372 3YSTEMS  4O A GOOD APPROXIMATION   WHEN A TARGET OF INTEREST IS ABOVE THE OPTICAL HORIZON OF AN (&372  THE FIELD INCI 
 16-28, January, 1955.  85. Hansen, R. 
 87  − S. Riegger; W. Wiesbeck, "Wide - band polarimetry and complex radar cross section  signatures," in Proc. 
 Fading complicates the interpretation of images by producing speckle . This means  that averaging of the speckled image usually is necessary. Sometimes the processor  does the averaging, and sometimes the interpreter does it mentally; it must be done to  interpret an image. 
  TO 
  
 Sector scan and the turning ofthe aircraft greatly complicate the scanner-synchronization problem. 17.15. AGround-to-ground Relay System.—The radar set originat- ingthedata inthis example isaground-based microwave set(see Chap. 
 CIVIL MARINE RADAR  22.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 Shipborne radar has had a remarkably long history. Its conception in the period from  1945 to 1948 was remarkably prophetic and still reverberates into the present century.  For this reason, a short Appendix to this chapter outlines the early steps in the evolu - tion of global standards for shipborne radar. 
 Variable attenuators have a number of advantages over variable gain amplifi - ers; they typically provide broader bandwidths, greater gain control accuracy, greater  phase stability, improved dynamic range, and faster switching speed. The choice between voltage controlled and switched attenuation depends on trade- offs between performance of a variety of parameters. Switched attenuators generally  provide maximum attenuation accuracy, faster switching speed, improved amplitude  and phase stability, greater bandwidth, higher dynamic range, and higher power han - dling capability. 
 The phase at each element is sequentially rotated at  some low frequency; the amplitude and phase of this modulation as received by the  probe relate directly to both the relative amplitude excitation of the element and its  ch13.indd   4 12/17/07   2:38:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 First sidelobes of from 40  to 50 dB below the main beam may be possible with the proper aperture illuminations and the  proper care in implementation. A high-gain antenna is usually necessary to achieve such low  sidelobes. (When referred to the radiation from an isotropic antenna, the peak sidelobes from a  low-sidelobe antenna might be approximately 10 to 15 dB below the isotropic level.) The . 
 Although anarrowbeamcan,ifnecessary, searchalargesectororevenahemisphere, itis notalwaysdesirable todoso.Usually, operational requirements placearestriction onthe maximum scantime(timeforthebeamtoreturntothesamepointinspace-)sothattheradar cannotdwelltoolongatanyoneradarresolution cell.Thisisespecially trueifthereisalarge numberofresolution cellstobesearched. Thenumberofresolution cellscanbematl:rial.ly reduced ifthenarrowangularresolution cellofapencil-beam radarisreplaced byabeamin whichonedimension isbroadwhiletheotherdimension isnarrow, thatis,afan-shaped pattern.Onemethodofgenerating afanbeamiswithaparabolic reflector shapedtoyieldthe. THE RADAR EQUATION 55  Figure 2.27 (a) Pencil-beam antenna pattern; (b)  fan-beam-antenna pattern. 
 Siegel: A Theoretical Method for the Calculation of the  Radar Cross Sections of Aircraft and Missiles, U 11i1>. Michigan Radiation Lah. Re11t ., 2591-1-H on  Contract AF 19(604)-1949. 
 Meas. 2017 ,66, 777–791. [CrossRef ] 24. 
 ATIONS MOTIVATED THE DEVELOPMENT OF 7IND3AT  A PASSIVE INSTRUMENT THAT ESTIMATES NEAR 
 Olin: Some Recent Observations of Sea Spikes, International Confert111ce  RADAR-77, pp. 115-119, Oct. 25-28, 1977, IEE (London) Conference Publication no. 
 [ CrossRef ][PubMed ] 17. Qu, Z.; Qu, F.; Hou, C.; Jing, F. Quadratic Frequency Modulation Signals Parameter Estimation Based on Two-Dimensional Product Modiﬁed Parameterized Chirp Rate-Quadratic Chirp Rate Distribution. 
 48, pp. 645–660,  1982. 145. 
 D" 3.2 AT THE RECEIVER INPUTS  ALTHOUGH THIS LOSS IS PARTLY REGAINED BY COHERENT ADDITION OF THE  3 
 314-318. 1966.  127. 
 22, 1946.  69. Croney, J., and J. 
 Cookc: Unsupervised Tracking of Maneuvering Vehicles, IEEE Trans.,  vol. AES-9. pp. 
 the intensity of precipitation is sometimes stated in terms of  ttic dl3 rcllcctivity factor Z = 200r' ', or dUz = 10 log Z. A rainfall rate of I mm/h eqi~als  23 dBz, 4 rnni/h equals 33 dBz. and 16 ~nmlh equals 42 dBz. 
 The theoretical loss calculated by the method described by Blevis was 3.4 dB. The experimen-  RADAR ANTENNAS 269 Weather effects.AgrouIH.l-based radarthatoperates without benefitofaradome mustbe designed towithstand windloads. 1o9i13Surveillance radarsmustnotonlybeabletooperate instrongwinds,butmustrotateuniformly. 
 use polarimetric scattering entropy to analyze the anisotropic scattering [ 13]. Li et al. propose an anisotropic scattering detection method to characterize targets [ 14]. 
 SCATTERED REFRACTIVE INDEX INHOMOGENEITIES 7ILSON AND 3CHREIBER HAVE FOUND THAT ABOUT  OF THE THUNDER 
 3EMICONDUCTOR &%4    -%3&%4 -ETAL 3EMICONDUCTOR &%4   AND (&%4 (ETEROSTRUCTURE &%4  4HE COMMON (&%4 DEVICES ARE REFERRED TO AS THE (%-4 (IGH %LECTRON -OBILITY 4RANSISTOR  AND 0(%-4 0SEUDOMORPHIC (IGH %LECTRON -OBILITY 4RANSISTOR  4O BE USEFUL IN A RADAR TRANSMITTER AMPLIFIER  THE TRANSISTOR MUST BE CAPABLE OF OPER 
 3!0 4IME 
 L. MacArthur, P. C. 
 Janza, R. K. Moore, and R. 
 Circular aperture.5.R Theexamples ofaperture distribution presented previously inthissec­ tionappliedtodistributions inonedimension. Weshallconsider heretheantenna pattern produced byatwo-dimensional distribution acrossacircularaperture. Thepolarcoordinates (r,0)areusedtodescribe theaperture distribution A(r,0),where I'istheradialdistance from thecenterofthecircularaperture, and0istheanglemeasured intheplaneoftheaperture with rcspecttoareference. 
 Pr.oc.. Soc.  Phoro-Optical Irrstr~rnrerrttltio~~ Etrgineers. 
 A pulse doppler bistatic radar was developed and tested to protect military aircraft on the ground from intruders.60 It was configured for near- forward-scatter operation. Five small portable transmitter-receiver units, typi- cally separated by 65 m, were located around the aircraft, with one transmitter servicing an adjacent receiver. In field tests the radar detected moving targets, including high-speed vehicles and intruders creeping at 2 cm/s. 
 29. Trizna, D. B.: Estimation of the Sea Surface Radar Cross Section at HF from Second- Order Doppler Spectrum Characteristics, Naval Res. 
 Scanning mayalsobeaccomplished byarranging aseriesoffeedsonthelocusofthefocal pointsofthetorusandswitching thetransmitter powerfromonefeedtothenextwithan organ-pipe scanner.128.129 Theprinciple oftheorgan-pipe scanner isshowninFig.7.17.The transmission linesfromthefeedsarearranged toterminate ontheperiphery ofacircle.Afeed hornisrotatedwithinthiscircle,transferring powerfromthetransmitter toeachfeedorgroup offeedsinturn.Therotaryhornmaybenaredtoilluminate morethanoneelementary feedof thcrowoffeeds.Allthetransmission linesintheorgan-pipe scanner mustbeofequallength. Theradiation patternfromatoruswithawell-designed organ-pipe scanner changes but littleuntilthebeamreachesoneendofthescanning aperture. Atthispointtheenergyappears athothcndsofthcaperture andtwobeamsarefoundinthesecondary pattern. 
 1,'igrlrc 12 7 is ;I plot of (lie clcct~ ic liclti stlctigtli (relative lo free sl,;tcc) at the target ;IS a  furlctiorl of the distarlce from t11e trarisrnitti~ig antenna. Botli the radar antenna and the target  arc assunled to he ;~t a fixed liciglit (100 n~ it1 tliis exan~ple). Tllc cornputed curves apply to  propagatio~i over an ide:1li7cd s~iiootli eartli iri the absence of a11 atmospiiere. 
 This  causes the most blockage at the pattern peak where the three rings intersect. Polarization plays a significant role in strut scattering. For the example shown in  Figure 12.12, strut #1 is parallel to the E-field and its blockage area is larger than its  actual physical cross section. 
 45. Van Vleck, J. H.: The Absorption of Microwaves by Uncondensed Water Vapor, PIlys. 
 29.Jakcman. E.,andP.N.Pusey:AModelforNon-Rayleigh ScaEcho.IEEETrailS.•vol.AP-24.pp. X06X14.Novemhcr. 
 The resulting output signal frequencies ( fL + fR and fL – fR) are the sum and difference  of the two input frequencies. In practice, all mixers produce unwanted intermodulation  ch06.indd   11 12/17/07   2:03:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 As discussed in Sees. 4.6 and 15.11, different kinds of instabil- ities are associated with a pulsed oscillator system and a pulsed amplifier chain. For the oscillator, pulse-to-pulse frequency stability depends on HVPS ripple, and intrapulse frequency changes depend on modulator droop and ringing. 
 With this assumption, fdma\ ~ T~ sm ^max f - 2v • aJdmin ~ Y" Sln ymin Thus the total width of the doppler spectrum is Wd = Y(sin 6max " sin 6min) A. For short pulses and angles away from vertical, this is A/rf « —A0 cos 9A In terms of pulse length, it becomes Afc-Sr^nr 02-") 2/iX sin 0 If the angular difference across the illuminated rectangle is small enough so that cr° is essentially constant, the doppler spectrum is a rectangle from/min to J max*In practice, antenna beams are not rectangular. The result is that the doppler spectrum for a side-looking radar like that of the example is not rectangular but rather has the shape of the antenna along-track pattern. 
 The waveguide switch and two scanners were the main change from ASV Mk. VI. The installation of ASV Mk. 
 Corey, “AN/APG-67 Multimode Radar Program,” in IEEE NAECON 1984 ,   p. 276. 47. 
 This multi-angle SAR is not required to adjust the antenna direction, nor large beam angle, which reduces the equipment requirements. SAR data from different angles can be obtained in one ﬂight, which reduces experimental costs. 2. 
 #  SATELLITERADAR  HTTPDIRECTORYEOPORTALORGPRES?3!2,UPE#ONSTELLATIONHTML  HTTPINDUSTRYESAINT!44!#(%-%.43!NFM?PDFSEARCH  *APANSPACERADAR)' 3 
 BASED RADARS  EASILY SATISFY THESE REQUIREMENTS /NE MEASURE OF AN IMAGING RADARS EXTENSIVE SIGNAL ENCODING IS THE PRODUCT OF ITS RANGE AND AZIMUTH TIME 
 following ways: (1)bysubstitutinga “constant current” device forR; (2)byadding the condenser voltage toE, thereby keeping the current through Rconstant; (3) byincluding ahigh-gain negative-feedback amplifier, sothat only anextremely small voltage need bedeveloped across the condenser. 1. 2.Apentode canbeusedas aconstant-current device. 
 As a consequence, the nominal single-look azimuth resolution from  a space-based SAR is r V V DAz Beam SC Az =( / ) / 2 rather than the famous “one half of the  aperture length” of airborne SARs. Note that VBeam is always smaller than the space - craft velocity, and decreases with increasing spacecraft altitude and incident angle.  Alert: In certain SAR processing literature, the effective velocity for the orbital case is  denoted “radar velocity,” a rather misleading and inappropriate term. 
 SYNCHRONOUS ORBITS BECAUSE THEIR PAYLOADS INCLUDE OPTICAL  SENSORS 4HE RESULTING HALF 
 The greater the number of faces, the less will be !he  loss in gain, beam broadening, VSWR variation, polarization change, and the number of  elements per face. Other factors which must be considered in selecting the optimum number of  faces are the number of transmitters and receivers, the complexity of the control of the array,  and the total cost.  Table 8.3 summarizes the properties of N array faces to give hemispherical coverage at a  single frequency.123 In the 5-and 6-face arrays, one face is normal to the zenith, which explains  why the tilt angle is less for these two cases. 
 A pronounced maximum of ducting conditions exists in the summer months on the eastern side of the Atlantic around theBritish Isles and in the North Sea. Mediterranean Region (Area 3). Available reports indicate that the seasonal variation in the Mediterranean region is very marked, with ductingmore or less the rule in summer. 
     %QUATION  IS EQUIVALENT TO THE MINIMUM MEAN SQUARE ERROR WEIGHT EQUATION  GIVEN BY 7IDROW  WHICH HAS BEEN SHOWN  TO BE THE OPTIMUM SET THAT MAXIMIZES  THE SIGNAL 
 ING HAS TRANSFORMED RADAR SYSTEM DESIGN AND TO GIVE SOME INSIGHT INTO THE TECHNIQUES AND TRADEOFFS THAT A DESIGNER HAS TO CONSIDER 7ITH MANUFACTURERS CONTINUALLY PRODUCING . Óx°În  2!$!2 (!.$"//+  FASTER AND MORE POWERFUL !$#S  $30 DEVICES  AND GENERAL 
 6.3.—Coarse andfineJ-scopes. Thepairofscopes shown isthatusedintheSCR-5s4 (Sec. 614). 
 FIG. 18.9 Block diagram of a conventional monopulse tracking radar. the range tracker. 
 Rm, vol. 70, pp. 938-946,  Dec. 
 When extensive and detailed radar performance calculations are to be made, a computer-stored base is required.HEIGHT, km . Frequency (MHz) (a) Frequency (MHz) (b) FIG. 24.9 The virtual (solid line) and true (dotted line) reflection heights are given for July, SSN = 50, and a mid-Atlantic-coast radar refraction area, (a) 1800 UTC is a daytime example, first hop. 
 Errorsofafewmetersmightnotbeofsignificance when cruising ataltitudes of10km,butareimportant ifthealtimeter ispartofahlindlanding system. Thetheoretical accuracy withwhichdistance canbemeasured depends upontheband­ widthofthetransmitted signalandtheratioofsignalenergytonoiseenergy.Inaddition, measurement accuracy mightbelimitedbysuchpractical restrictions astheaccuracy ofthe frequency-measuring device,theresidual path-length errorcausedbythecircuitsandtrans­ missionlines,errorscausedbymultiple reflections andtransmitter leakage,andthefrequency errorduetotheturn-around ofthefrequency modulation. Acommon formoffrequency-measuring deviceisthecyclecounter, whichmeasures the numberofcyclesorhalfcyclesofthebeatduringthemodulation period.Thetotalcyclecount isadiscrete- number sincethe.counter isunabletomeasure fractions ofacycle.The discreteness ofthefrequency measurement givesrisetoanerrorcalledthejixed error,or!;[t/p error.Ithasalsobeencalledthequantization error,amoredescriptive name.Theaverage numberofcyclesNofthebeatfrequen<;y fbinoneperiodofthemodulation cycleJ~islblfm, \ wherethebaroverfi,denotes timeaverage. 
 Carbone, R. Strauch, and G. M. 
 Parameterized Ionospheric Model, Computational Physics, http://www.cpi.com/products/pim/. 40. R.E. 
 The definitions of power gain and directive gain were described above in terms of a  transmitting antenna. One of the fundamental theorems of antenna theory concerns reci-  procity. It states that under certain conditions (usually satisfied in radar practice) the transmit-  ting and receiving patterns of an antenna are the same.' Thus the gain definitions apply equally  well whether the antenna is used for transmission or for reception. 
 Aphaseshifting technique thatusesafrequency change, but whichthenconverts backtoaconstant frequency, istheHuggins phaseshiftershownin Fig.8.19.Asignaloffrequency fa,whosephaseistobeshiftedanamount¢'ismixedwitha signalfromavariable frequency oscillator feinthefirstmixer.Theoutputofthevariable­ frequency oscillatorfc isalsopassedthrough adelaylinewithatimedelayr.Theoutputofthe delaylineisasignaloffrequency Iewithaphaseshift¢=2nfer.Thisphase-shifted signaland theoutputofthefirstmixerarethenheterodyned inthesecondmixer.Ifthesumfrequency is selected fromthefirstmixer,thedifference frequency isselected fromthesecondmixer.The resultisasignalwiththesamefrequency astheinputfo, butwiththephaseshift¢.Because mixersareemployed, thistypeofphaseshifteroperates atlowpower.Itisconvenient to implement atIF,although itisalsopossible toemploy theprinciple atRF.Atappeddelay. 304 INTRODUCTION TO RADAR SYSTEMS  Vorioble i  Figure 8.18 Volumetric scanning of a planar array using frequency scan in one coordinate and phase-shift  scan in the other. frequency -1  signol 7.7  -  Figure 8.19 Schematic representation of the t-luggins '/  phase shifter. 
 BAND TRANSMITTERS TO MINIMIZE ATTENUATION !IRBORNE AND GROUND CLOUD RADARS AND SPACEBORNE RADARS ENCOMPASS THE MM 
 61. Symonds, M. D., and J. 
 Other designs have  resulted in pulse widths as long as 100 ps and pulse-compression ratios as high as 10,000.22  The SAW dispersive delay line is one of the more important of the many devices that have  beer] errlployed for pulse-compression radar. They have been claimed to be simple, low cost,  Figure 11.18 Interdigital transducer (nondispersive) showing  overlap of comb fingers, or electrodes, to provide an amplitude  weighting along the pulse.  EXTRACTION 01'INFORMATiON ANDWAVEFORM IJESION 425 [)IspersiveIransduccr.+. 
 The various receiver types listed in table 2.2represent variations and improve- ments applied to the Pye and Cole receiver designs. R.3084A was the same as R.3132, but manufactured by Cossor. Aircraft that had the Common T & Rinstalled (see section 2.2.4) used R.3132B, which was a modi ﬁed version of R.3132 with a spark gap (VI 507) across the aerial input and a switch ﬁtted to the front panel Figure 2.9. 
 HH HH   WHERE G AND GG ARE THE INTRINSIC IMPEDANCES OF AIR AND EARTH  RESPECTIVELY 4HE FRACTION  OF TOTAL INCIDENT POWER SPECULARLY REFLECTED FROM A ROUGH SURFACE IS  EH 
 718 RADAR RELAY [SEC. 17.11 suppressed. Frequency modulation isthus helpful incases where itis desirable toremove thelast traces oflow-level interference. 
 80  70  60  50 ·  40 ("  30  20  10  9 • 8  7  r, ry  5 i;:  ~  4 (/)  ,,  b{.) ----· •  ----x  ~ (l  0 _, \  \ \ x---x - \ I  \ I  \ I - \ I "3  \ I CJ'>  '\ I g' .x I . ;: \ g I cu \ er, :r  \ I  "  Weight of bird, g figure 13.14 Radar cross section of birds  (with closed wings) at S band. Vertical  polarization. 
 The latter dimension is sometimes called cross range  when the radar uses a side-looking antenna ~irected. perpendicular to the direction of motion.  The range resolution is obtained with either a conventional short-pulse or pulse-compression  waveform, and resolution in cross range is obtained by synthesizing the effect of a large  antenna aperture. 
 The reference waveform pulsewidth is TR = 50 + 0.25 = 50.25 µs to avoid a loss in SNR  for targets at the edges of the range window. The swept bandwidth of the reference  waveform and the range window width are  BR= × = 20MHz/s50.25 s1005 MHz µ µ    ∆ ∆rct = = × =2150 m s 0.25 s37.5 m µ µ   The 6-dB range resolution width with Hamming weighting applied over the 50-µs  pulsewidth in the spectral analysis processing is   ∆Rc B61 8121 811500 27 = = = . .m s 1000 MHzmµ   Cobra Dane Wideband Pulse Compression System. 
 SIGHT 4HE OCEANS REFLECTIVITY IS ALSO A FUNCTION OF OTHER FACTORS  INCLUDING SURFACTANTS SUCH AS OIL SLICKS  EITHER NATURAL OR ANTHROPOGENIC   THE AIR 
 Desai, C. V . N. 
 J. Elecrrott., (London), vo!. 1, pp. 
 Long: A Lunehurg Lens Scanning System. IRE Tratts., vol. AP-5, pp. 
 79. J. Frank, “Bandwidth criteria for phased array antennas,” in Phased Array Antennas , A. 
 2, New York, NY , 1957, pp. 186–200. 27. 
 Wylder, “The frontier for sensor technology,” Signal , vol. 41, pp. 73–76, 1987. 
 14.3. FIG. 14.3 Transmission bridge, video version. 
 pp. 27-30. July,  1974. 
 Since the  radar is performing tracking and other functions as well as search, conflicts in scheduling the  radar or the processor might arise. Tracking functions are often more critical of time than  search. and would have a higher priority in the event of a scheduling conflict. 
 Unfortunately, target angle and range scintillation power density is  normally concentrated below about 1 to 2 Hz when operating at microwave bands and  falls within normally required bandwidths. Target scintillation total noise power is relatively independent of frequency, but  the spectral energy tends to spread upward in frequency as wavelength is reduced,  resulting in lower noise power density in the servo passband. Therefore, operating at a  shorter wavelength will result in lower target noise effects on closed-loop tracking. 
 obtained inthis way. The experiments upon which Table 2.2isbased were performed inthelabora- tory under ideal conditions ofobservation; moreover, thevalue ofw(the parameter ofTable 21) ishere certainly much too large forany radar search operation, although itmight notbeinappropriate forthecontinuous tracking ofatarget already detected. The experimental determination ofthe maximum range ofanactual radar setisasuncertain amatter asisthe calculation ofthe maximum range bythemethod outlined inthis chapter. 
 CPI = 9 pulses. Optimum is from Figure 2.26. ch02.indd   56 12/20/07   1:45:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 PARAMETER 'AMMA DISTRIBUTION 4HEY ALSO REVIEW THE DEPEN 
 62, pp. 673-680. June, 1974. 
 3, pp. 66–73, May 2002. On occasion  of the 2001 B. 
 S. A. Hovanessian, Radar System Design and Analysis , Chapter 12, Norwood, MA: Artech House,  Inc., 1984. 
 1079–1090.  197. A. 
 The angle-error detector, assumed to be a produce detector, has an output  | || || |e k=∆Σ Σ Σcosθ (9.2) where | e | is the magnitude of the angle-error voltage. Phases are adjusted to provide  0° or 180° on a point-source target. The resultant is  | || |e k= ±∆ Σ (9.3) IF AMPLIFIER IF AMPLIFIERAGC VOLT AGEΣ ∆ AGC AMPLIFIERDETECT OR ANGLE ERR OR DETECT OR FIGURE   9.9  AGC in monopulse tracking ch09.indd   10 12/15/07   6:07:12 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Itisprovided with sensitivity- time control (Sec. 12.8). The video output signals ofthebeacon receiver gotoavideo mixer with controls soarranged that the indicator will display either radar signals alone, radar and beacon signals together, orbeacon signals alone. 
 Solid-state HF radar transmitters operate at power efficiencies lower than those  based on vacuum tube amplifiers. Vacuum tube amplifiers are also more robust and  have been used successfully in a number of HF skywave radars including the AN/FPS- 118. The adoption of solid-state amplifiers in radars such as ROTHR and Jindalee/ JORN is driven by the need to accommodate instantaneous frequency switching over  wide bandwidths while maintaining high linearity and spectral purity. 
 (13.6), waveheight is proportional to the square of the wind speed; so in the Gulf Stream, for example, with a current of 4 kn flowing north, a 15-kn northerly blowing against the current will raise a sea 3 times as high as a 15-kn southerly blowing with the current. Even with no wind the presence of strong current shears can produce highly agitated surfaces. Shipboard observers have reported bands of roaring breakers passing by on an otherwise-smooth surface, presumably pro- duced by powerful surface-current shears associated with large-amplitude inter- nal waves.69 In a more subtle way, currents are held responsible for synthetic aperture radar (SAR) images which contain the expression of bottom topography in shallow waters.70 In each of the examples cited above, the current produces a change in the surface roughness, which can be expected to give rise to a change in sea clutter cross section. 
 D" -AINLOBE 7IDTH  S &ILTER -ATCHING ,OSS D"  5NIFORM 
 TO 
 OF 
 FORM (OWEVER   @  CANNOT BE MADE ARBITRARILY LARGE BECAUSE THE COMPRESSED PULSE  TENDS TO DISTORT #OLLINS AND !TKINS DISCUSS AN EXTENSION OF THE TANGENT 
 The vast  majority of radar antennas use the parabolic reflector in one form or another. Microwave  lenses have also found some radar application, as have mechanically rotated array antennas.  The electronically scanned phased array, described in Chap. 
 However,  a large gate area is required if the tracker is to follow target turns or maneuvers. More than  one size gate might therefore be used to overcome this dilemma. The size of the small gate  would be determined by the accuracy of the track. 
 LAR DOPPLER SPECTRUM CHARACTERISTICS BECAUSE THE RADAR IS STATIONARY 4HIS MEANS THAT SIDELOBE CLUTTER APPEARS AT ROUGHLY THE SAME DOPPLER SHIFT AS MAIN BEAM CLUTTER AND DOPPLER FILTERING CAN BE USED EFFECTIVELY FOR DETECTING TARGETS USUALLY WITHOUT SPECIAL NEED TO REJECT THE SIDELOBE CLUTTER SPATIALLY    /BVIOUSLY THE SITUATION MAY CHANGE IN SHIPBORNE (& SURFACE WAVE RADAR BECAUSE THE PLATFORM IS MOVING WITH  RESPECT TO THE SEA SURFACE AND HENCE A CONCEPTUALLY SIMILAR SITUATION ARISES FOR THE CLUTTER AS ENCOUNTERED IN AIRBORNE RADAR. Ó{°x{  2!$!2 (!.$"//+  Ó{°£ÓÊ 
 CORRELATOR  IS USED ON RECEPTION %QUATION  IS RELATED TO THE CORRESPONDING MONOSTATIC MAXIMUM RANGE EQUATION BY  2 4 22   2- AND R-   R"  WHERE R- IS THE  MONOSTATIC RADAR CROSS SECTION  &OR PULSED RADAR OPERATION   TO   N  FP  WHERE N IS THE  NUMBER OF PULSES INTEGRATED AND  FP IS THE PULSE REPETITION FREQUENCY !LSO  THE SIGNAL 
 The radar designer isinclined to take advantage ofthis latitude toset@somewhat greater than 1.2/7 as this eases therequirement ofaccurate frequency control. .Avallle ofCB inthe neighborhood of2/r istypical ofpresent practice; there issome evidence also from controlled experiments onintensity-modulated indi- cators (Vol. 24,Chap. 
 Either ofthese events may occur only once ortwice permillion pulses, but when such anevent does take place, voltage and current surges arefrequently produced inthe pulser which may cause failure ofsome component. The pulser designer must there- fore over-design components and provide special protective circuits to guard against events that may happen only once inamillion pulses. All magnetrons change mode orspark occasionally, but the frequency of sparking ormode-changing canbereduced byoperating atmoderate peak anode currents and short pulse durations. 
 high-prcssure cellsandtheequatorial doldrums. Twosuch tradewind areasthathavebecnstudicd liebetween BrazilandtheAscension Islands29and betwccn Southcrn California andlIawaii."'o Thetradewind temperature inversion isusual1y foundovertheeasternportions ofthetropical oceans.Intheseregions,thereisaslow-sinking ofhigh-altitude air(large-scale subsidence) whichmeetslow-level maritime airflowingtoward theequator. Thegeneralsinkingofairfromhighaltitudes resultsinadiabatic heatingdueto compression. 
 40.Weinstock, W.:"Target CrossSectionModelsforRadarSystems Analysis," doctoral dissertation, University ofPennsylvania, Philadelphia, 1964. 41.Scholefield, P.H.R.:Statistical AspectsofIdealRadarTargets, Proc.IEEE,vol.55,pp.587-589, April,1967. 42.Pollon,G.E.:Statistical Parameters forScattering fromRandomly Oriented Arrays,Cylinders, and Plates,IEEETrans.,vol.AP-18,pp.68-75,January, 1970. 
 This can limit the ultimate receiver sensitivity, especially at high altitudes.  4. The interference due to power being reflected back to the transmitter, causing a change in  the impedance seen by the transmitter. 
 IN NAVIGATIONAL CALCULATIONS ARE BEING MADE (AVING A DEFINED ##20 ALSO ALLOWS A SCALED OWN 
 With many military radars, the exact operating fre - quency range of a radar is usually not disclosed. Thus, the use of letters to designate  radar operating bands has been very helpful. The IEEE (Institute of Electrical and  Electronic Engineers) has officially standardized the radar letter-band nomenclature,  as summarized in Table 1.1. 
 L. B. Wetzel, “A time domain model for sea scatter,” Radio Sci ., vol. 
 A. A. Acker, “Eliminating transmitted clutter in doppler radar systems,” Microwave J ., vol. 
 Ohio). pp. 133-144. 
 Targets can be discriminated if we ﬁnd a method to quantify the anisotropy by a calculation. The calculation should be concerned with the scattering mechanism from different angles of view and not the RCS amplitude. p      (a)  (b) (c) (d)  Figure 1. 
 OF 
 Although these modern spatio-temporal adaptive processing techniques have been  proven to be highly effective,136 the computational and data requirements are so high  that most of them cannot be implemented in their most powerful forms for real-time  processing. Instead, simplified algorithms with impressive but nonetheless subopti - mum performance are employed.137,138 In view of the number of simultaneous spatial cells to be considered, detection  is generally based on a constant false alarm rate (CFAR) algorithm adapted to the  particular clutter environment. In most implementations, the CFAR detection thresh - old is computed for each resolution cell as a linear combination of order statistics  extracted from ranked sample values over a window spanning neighboring range  bins, antenna beams, and doppler cells, with provisions for adapting the window  shape near strong variations in noise or clutter power. 
 The noise figure of a radar receiver can degrade in operation and  cause reduced capability. Therefore some means for monitoring the noise figure should be  provided in operating radars so that a worsening of receiver sensitivity can be detected and  corrected. The monitoring of the noise figure can be accomplished either automatically or  manually by the operator. 
 J. K. Hill, “Exact ray paths in a multisegment quasi-parabolic ionosphere,” Radio Science , vol. 
 frequency of  scatterers illuminated by tlie center of the antenna beam is zero. It is possible. however, to  operate with the antenna beam pointed either forward or aft of broadside. 
 Shortcut connection. Figure 1b presents Resnet-34 models. Table 1presents Resnet models with different layers. 
 FREQUENCY POWER 
 D.: A Diplex, Doppler Phase Comparison Radar, IEEE Truns., vol. ANE-10, pp. 27-33,  March, 1963. 
 OF 
 I,30.366';,: 30.281I. 30.263 30244 . ELEVATIONlDEGREESl __._J3.028tC----i-.I--+-i-+. 
 erigirice~ 11 tlescr il~cs tl~c eriveloi~c of (lie ~ioisc outlxrt fro111 ii rlar r.owbatld filtcr (sucli as tile IF  filter iri a sr~pcrheterotlyne receiver). tile cross-section fluctuatioris of certain types of conlplex  radar targets. arid rnariy kinds of clutter arid weather echoes. 
 Methods ofreducing this noise are ofprime importance inradar receiver design. Not only must noise be kept down, but everything possible must bedone tominimize attenua- tion ofthe signal before itisamplified. How this has influenced the design ofr-fcomponents hasalready been seen. 
 3. Tentative correlation with some track  DF signal probably goes with some radar  track (but cannot determine which) when Pmax ≥ TM but Pmax < Pnext + R. 4. 
 We can express Eq. (12.12) in terms of these coordinates as dnl" X2 1 f\Pfl2^d(\ wrfd = ^\-^\ \ A \ <12-13>#'WJ ipL R4 J Note that P19 the transmitted power, is nonzero in the integral only for the time it illuminates the ground. In pulse radars, only that part of the ground area provid- ing signals back to the radar at a particular time can be considered to have finite Pt9 and so the range of frequencies that can be present is limited by the pulse, as well as by the antennas and the maximum velocity. 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 abbreviated to 17 days), 108 ° inclination, (consequently 160 km track-to-track spac - ing at the equator), and 784 km altitude.§ From the Geosat orbit, half of the princi - pal tidal constituents alias into unwanted frequencies (near zero, one, or two cycles   per year). In particular, the dominant tidal constituent, the common twice-daily lunar  tide, is aliased to 317 days, which is close to the annual cycle.81 Precision orbit  determination is good to only about 7 cm, which is relatively large, due in no small  measure to failure of the primary onboard GPS navigation subsystem. 
 The antennas aredifferent inthat thelow-angle reflector is8fthigh and parabolic invertical section, itsradiation vertically polarized; whereas thehigh-angle reflector is5fthigh, ofanempirically determined shape producing anapproximately cosecant-squared beam, and itsradiation horizontally polarized. The reflectors arenotperforated forthereason that thesmall amount. 288 ANTENNAS, SCANNERS, AND STABILIZATION [SEC. 
 However, the usual photograph or drawing of a phased-array radar  seldom reveals the amount of electronic equipment behind the array face that is required to  make it a useful radar.  Another of the advantages sometimes claimed for an array radar is that it is capable of  performing more than one function simultaneously; for example, it can do surveillance of a  volume as well as track individual targets. The multifunction attribute of an array radar has . 
 In many applications of AGC the delay voltage is actually zero. This is called undelayed  AGC. In such cases the AGC can still perform satisfactorily since the loop gain is usually low  for small signals. 
 CATIONS IN OCEANOGRAPHY  GEODESY  GEOPHYSICS  AND CLIMATOLOGY  7ITH THE EXCEPTION  OF NEAR 
 Itmight therefore appear that the V-beam system eludes the very restrictions which have been claimed tobefundamental. This istobe explained bythe fact that the V-beam height-finding method works only ifrelatively few targets appear onthescreen atone time; otherwise there isessential ambiguity inthe interpretation ofthe picture. The system is,therefore, not fully equivalent toapencil-beam scan ofthe same angular region. 
 The sur- rounding reference cells are then used to estimate the unknown parameters, and a threshold based on the estimated density is obtained. Nonparametric detectors obtain a constant false-alarm rate (CFAR) by ranking the test samples (ordering the samples from smallest to largest), usually with the reference cells. Under the hypothesis that all the samples (test and reference) are independent samples from an unknown density function, the test sample has a uniform density function, and, consequently, a threshold which yields CFAR can be set. 
 SCAN TRACKING RADARS  4HE VULNERABILITY OF  CONICAL SCAN TO SUCH COUNTERMEASURES MOTIVATES THE USE OF MONOPULSE TRACKERS THAT ARE ALMOST ALWAYS USED IN MILITARY TRACKING RADARS ! DIFFERENT FORM OF $%#- USED AGAINST THE MAIN BEAM OF SURVEILLANCE RADAR  ATTEMPTS TO COVER THE TARGETS SKIN RETURN WITH A WIDE PULSE IN ORDER TO CONFUSE THE RADARS SIGNAL 
 D. O. North2 demonstrated that the detectable signal-to-noise ratio (Sl A0min will have its smallest possible value when the receiver bandwidth Bn has a particular (optimum) value and that this optimum value of Bn is inversely proportional to the pulse length T. 
 TIONS BASED ON NUMERICAL METHODS EXPLORED AND EXPANDED THE IDEA OF SHADOWING OVER THE SEA SURFACE UNDER HIGHLY IDEALIZED   AND MORE GENERAL CONDITIONS 3URFACE #URRENTS  4HE MOST OBVIOUS EFFECT OF A CURRENT ON SEA CLUTTER WOULD BE  A SHIFT IN THE PEAK OF THE DOPPLER SPECTRUM  ANALOGOUS TO THE CONTRIBUTION OF THE  WIND 
 Zverev, A. I.: Digital MTI Radar Filters, IEEE Trans. vol. 
 Ê  Ê 9   ,  
 IZATION AT A LOOK 
 pp. 25-33. January. 
 Early HF radar experiments established that the strong ground clutter observed  via skywave provided an indication of the physical characteristics of the illuminated  terrestrial surface. Extensive observations made at the Naval Research Laboratory  viewing alternately Atlantic Ocean areas and central United States areas indicated  that, averaged over a wide area, sea clutter power levels were usually about an order of  magnitude higher than those from an area of similar size in the central United States.  Later observers noted extremely low backscatter from ice-covered areas of Greenland. 
 105.  93. Houghton. 
 Cummings, Freeman, and Benz: Deployable Parabolic Antenna, U.S. Patent 3,789,375, Dec. 18, 1973, assigned to Rockwell Inc. 
 One method of accounting for a fluctuating cross section in the radar equation is to select  a lower bound, that is, a value of cross section that is exceeded some specified (large) fraction  of time. The fraction of time that the actual cross section exceeds the selected value would be  close to unity (0.95 or 0.99 being typical). For all practical purposes the value selected is a  minimum and the target will always present a cross section greater than that selected. 
 Examples of  an L band two-stage low-noise  amplifier GaAs MMIC and an  X band power amplifier GaAs  MMIC are shown in Figure 11.18  and Figure. 11.19, respectively.FIGURE 11.18  L-band low-noise amplifier MMIC. Shown  here are the spiral inductors, metal-nitride-metal capacitors,  and via-hole connections to ground. 
 All RF tubes produce some in-band background noise level. In a 1-MHz bandwidth,  this noise might be 50 to 60 dB down in conventional CFAs, 70 to 80 dB down in the  low-noise-high-gain CFA, and 90 dB down or better in linear-beam tubes. In-band  spurious cannot normally be improved with filters because it occurs within the same  frequency range as the desired signal spectrum. 
 Skillman, W. A.: Microwave Technology, Key to AWACS Success, Proc. IEEEMTTI S, Boston, 1983. 
 4 to 2.7 canonical filter design, 2.34 clutter attenuation (CA), 2.20 to 2.21 clutter characteristics, 2. 10 to 2.19 clutter filter-bank design, 2.52 to 2.59 cl utter filter response, 2. 9 to 2.10 clutter maps, 2. 
 Second, the PRF set should all be clear at  the maximum design range so that detection losses are at a minimum. Figure 5.17 shows one example criteria for selecting the central PRF, i.e., the high - est probability of visibility ( PV).45 In the example, the product ( PV) of the range ( PR)  and doppler ( PD) target visibility probabilities for a single PRF peaks at approximately  0.47 and thus the other PRFs must fill in to reach 96% clear or higher. There are several FIGURE 5.16  Medium PRF range-velocity blind zones ch05.indd   18 12/17/07   1:26:49 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Further reduction ofleakage power is neceseary, however. This may bedone byastep-up transformer tothe gap, and anidentical step-down transformer tothereceiver line. Inthe unfired condition, the standard line impedance ismaintained oneither side oftheTR switch, but inthefired condition theline impedance seen atthe gap appears tobevery high and much less power iscoupled out tothereceiver.. 
 B. D. Carlson, L. 
 This is SAR. The equipment remains the  same–just the explanation changes. Conception was reported in a Goodyear Aircraft  report in 1951.”12 Subsequently, as described in Section 8.1 of Schleher,16 DBS came to refer to an  airborne scanning mode in which the echoes from the scanning real beam are doppler- processed to produce crossrange resolution finer than that provided by the real beam  alone; broadside crossrange resolution is ≈ Rl /2LDBS, where LDBS is the synthetic aper - ture length generated during a target dwell. 
 44. F. M. 
 5, pp. 415-432, Srptemher, 1977  10. Tomiyasu, K.: Phase and Doppler Errors in a Spaceborne Synthetic Aperture Raddr lmag~ng the  Ocean Surface, IEEE Jour. 
 The form of the radar equation described in this chapter  applies to a radar that dwells on the target for n pulses. It is sometimes called the searchlight  range equation. In a· search or surveillance radar there is usually an additional constraint  imposed that modifies the range equation significantly. 
 The theoretical peak power capability of the switched line  is twice that of the hybrid-coupled circuit since voltage doubling is produced by the reflection  A ;-$-I C4' 4- A ;ir,l-[ir140  Input Output  Figure 8.8 Periodically loaded-line phase shifter.  TIlEELFCTRONICALLY STEEREO PHASED ARRAY ANTENNA INRADAR289 Input Output -0--. --_ x3-dB hybrid junction j iii f:' Figure8.7Hybrid-coupled phasebit. 
 TION ,$2 IS A RATIO OF THE CROSS 
 DOWN ANGLE OF  . Óä°Îä  2!$!2 (!.$"//+  RAINFOREST  PROVIDES A GEOGRAPHICAL REFERENCE THAT CAN ASSIST WITH THE EVER 
 STATE TRANSMITTERS 3OME INITIATIVES  SUCH AS THE SOLID 
 Marshall: The Distribution with Size of Aggregate Snowflakes, J. hlrtror.,  VOI. 15, pp. 
 While noise may be non-Rayleigh, it will probably be very Rayleigh-like out to the tenth percentile. Furthermore, one can use feedback based on several FIG. 8.13 Implementation of a binary integrator. 
 KM ALTITUDE 4HE RADAR TRANSMITS  §SEC LINEAR &- SIGNALS THAT ARE DEMODU 
 Nose-on incidence lies at the center of the patterns, and the sharp peaks near the sides are the specular returns from the slanted sides of the cone, also called specular flashes. The RCS formula for singly curved surfaces given in Table 11.1 may be used to predict the amplitudes of the specular flash within a fraction of a decibel. At precisely nose-on incidence the RCS must be independent of polar- ization because the cone is a body of axial symmetry. 
 PROCESSING BANDWIDTH !DDITIONAL GAIN IS PROVIDED AT )& TO  OVERCOME LOSSES AND  RAISE THE SIGNAL LEVEL REQUIRED FOR SUBSEQUENT PROCESSING AND TO SET THE CORRECT SIGNAL LEVEL INTO THE !$ CONVERTERS !N )& LIMITER PROVIDES GRACEFUL LIMITING OF LARGE SIGNALS THAT WOULD OTHERWISE OVERLOAD THE !$ CONVERTERS 4HE TWO DOMINANT METHODS OF  DIGITIZATION  )& SAMPLING AND ANALO G )1 DEMODULA 
 MOGENEITIES CAUSED BY NATURALLY OCCURRING ATMOSPHERIC TURBULENC E  4HE ANTENNA  SYSTEMS USUALLY TAKE THE FORM OF PHASED ARRAYS THAT FORM BEAMS SEVERAL DEGREES WIDE THAT ARE SWITCHED TO     OR  NEARLY VERTICAL BEAMS FOR n MINUTES EACH AND MEASURE VERTICAL PROFILES OF WIND EVERY n MINUTES 4HE ANTENNAS ARE FREQUENTLY  OF THE COAXIAL COLLINEAR CO 
 A. V., and P. 0. 
 NOISE RATIO 5NFORTUNATELY  THIS WILL ALSO CAUSE THE RATIO DETECTOR TO DECLARE FALSE ALARMS IN THE PRESENCE OF N ARROW 
 This relation has been strikingly verified bytheexperiments ofJ.L.Lawson and others (Vol. 24) inthe detection ofsignals onthe A-scope, under conditions where nwas large. On the other hand, for small n,and especially forvery small values ofw,Table 2.1would require the signal power tovary more nearly asI/n. 
 TRACKING ERROR INDICATION AND THE CLOSED 
 2, vol. 18, pp.  104-109, December, 1945; pt. 
 Brookner, “Phased array radars,” Sci. Am ., vol. 252, pp. 
 When a feed is designed to illuminate a reflector with a particular taper, the distance p to the surface must be accounted for, since the power density in the spherical wave falls off as 1/p2. Thus the level at the edge of the reflector will be lower than at the center by the product of the feed pattern and this "space taper." The latter is given in decibels as (4//Z))2Space taper (dB) = 20 log (6 15) 1 + (4//D)2 Equation (6.15) is graphed in Fig. 6.6, showing a significant contribution at the smaller focal lengths. 
 They all can give the correct values for .. use . .in the radar equation provided I he  assumptions used by each author are understood. 
 • The increased capability of military airborne radar (airborne intercept, AW ACS, and AEW) due to advances in components and technology that permitted the application of AMTI and pulse doppler to the detection of aircraft in the midst of large clutter. • The use of radar in space for rendezvous and landing, remote sensing of the earth's environment, planetary exploration, and the detection of targets on the oceans of the world. • The use of semiactive radar for the guidance of military missile systems. 
 Automatic gain control. 9 -1 1 The echo-signal amplitude at the tracking-radar receiver will  not be constant but will vary with time. The three major causes of variation in amplitude are  ( 1) the inverse-fourth-power relationship between the echo signal and range, (2) the conical­ scan modulation (angle-error signal), and (3) amplitude fluctuations in the target cross  section. 
 On the other hand, for  UHF radiation, attenuation varies from 0 to ≈ 20 dB; half the time it is less than ≈ 7 dB.  Thus, for FOPEN, UHF radiation is necessary: shorter waves will not penetrate the  foliage, whereas for airborne applications, longer waves would require prohibitively  large antennas. (Specific values of attenuation [dB/meter] vary with grazing angle, tree  type, leaf density, and moisture content; however, the previous statement is a general  summary of these results; further details are given in Fleishman et al.55) The aperture time tA required to collect sufficient data for a SAR image is found from  Eq. 
 The Nexrad radar makes use of a hail-detection algorithm that combines  a high reflectivity factor with echo height and upper-level divergent radial velocity  winds to detect the occurrence of hail. Polarimetric radar techniques improve quantita - tive hail detection. Bringi et al.,15 Aydin et al.,144 and Illingworth et al.145 proposed a  hail detection technique using differential reflectivity measurements. 
 2-10, March/April. 1967. ,. 
 Norwood, MA: Artech House, Inc., 1978, pp. 299–301. 39. 
 Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). 329. 
  TER 
 A review of ground-based SAR interferometry for deformation measurement. ISPRS J. Photogramm. 
 A  bowl-shaped reflector as part of a radio obstacle detector  was fitted near the bridge of the Normandie in 1935, and  a year later a decimetre radio set was installed by the  S.F.R. at the entrance to the port of Le Havre, at Saint-~  Adresse. A 10-centimetre radio link was also used  across the Channel in 1934, the British organization of  Standard Telephones and Cables being concerned with  these tests, and a number of phenomena, now easily  explained in the light of our present radar knowledge,  were observed. 
 W. T. Patton, “Low Sidelobe Antennas for Tactical Radars,” IEEE Int. 
 van der Merwe, and A. T. Nelson, “Dual estimation and the unscented transforma - tion,” in Advances in Neural Information Processing Systems 12 , Cambridge: MIT Press, 2000,  pp. 
  AND  RAIN 
 Diversity techniques, which can provide statistically independent samples of target  scintillation, offer a means for reducing target scintillation effects. The most practical  technique is frequency diversity using pulse-to-pulse radar frequency change, which  will alter the phase relations between the echoes from dominant reflecting surfaces  of the target.59–62 The frequency change must be sufficient to cause enough change in  relative phases of the reflectors to result in statistically independent samples of target  scintillation at each new frequency. An approximate rule is a minimum frequency  change of 1/ t, where t is the radar range delay time between the leading and lagging  extremities of the target. 
 The following steps must occur before radar information isintheform inwhich itwas used fordecision and action: 1.The coordinates ofatarget signal areread offthe display atthe radar station. 2.Anumber isassigned tothis particular track, onwhich continuous plotting will bemaintained. 3.Anattempt ismade toidentify thetrack from thefollowing data: a.Known location offriendly aircraft. 
 ING OF THE TARGET IMAGE EVEN IN RANGE  AS WELL AS IN CROSS RANGE   4HE TARGET ECHO CAUSES A DETECTION AND INITIALIZES THE MOTION ESTIMATION CHANNEL 4HE HIGH ;FINE= RESOLUTION DATA ARE INITIALLY SMOOTHED IN RANGE TO DECREASE ;COARSEN= THE RANGE RESO 
 LENGTH INPUT SEQUENCE CENTERED AT THE FREQUENCY MF S. )F AN INPUT SIGNAL IS EXACTLY CENTERED IN ONE OF THE $&4 FREQUENCY BINS  THE OUTPUT  WILL HAVE A MAXIMUM VALUE FOR THAT BIN AND NULLS FOR ALL OTHER  BINS (OWEVER  ANY FRE 
 Returns that appear at these  incorrect ranges are referred as  ambiguous returns or second time around (second -sweep) echoes. The pulse width τ in this  equation  indicates that the complete echo impulse must be received.  R is the slant range   tdelay  is the time taken for the signal to travel to the target  and return   c0 is the speed of light (approximately 3·108 m/s)    Figure 6: a second -sweep echo in a distance of 400  km assumes a wrong range of 100 km  . 
 ch01.indd   1 11/30/07   4:33:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 
 DURE TO THAT DESCRIBED ABOVE FOR RANGE &OR THIS  AN ACCURATE ESTIMATE  }  FDI  OF THE  AMBIGUOUS TARGET RADIAL VELOCITY MUST BE OBTAINED AT THE RANGE CORRESPONDING TO THE AMBIGUOUS PRIMITIVE TARGET DETECTION ON EACH #0) 4HIS FREQUENCY ESTIMATION PROBLEM HAS BEEN STUDIED BY MANY AUTHORS WITH THE BEST APPROACH BEING DEFINED . Ó°ä  2!$!2 (!.$"//+  BY THE MAXIMUM LIKELIHOOD ESTIMATE &OR A SINGLE 
 Thus the  signal- to-noise ratio per pulse of the tnultiple-beam radar is less than the signal-to-noise ratio  of !he scanning-beam radar. If these N pulses are integrated without loss as in a perfect  predetection integrator, the total signal-to-noise ratio in the multiple-beam radar just conipen-  sates for the lesser transmit gain. Thus the multiple-beam radar and the scanning-beam radar  have equivalent detection capability, provided the data rates are the same and integration is  without loss. 
 In this case, target location accuracy is often set by the q T estimation error. Multistatic Location.9,14,65 Multistatic location typically uses multiple transmitters  operating with one receiver or multiple receivers operating with one transmitter. Ellipses  of constant range-sum, i.e., isorange contours, from each transmitter-receiver pair are cal - culated and combined at a central site to produce intersecting contours, which locate the  target. 
 CLUTTER RATIO OF A MOVING TARGET WHEN CLUTTER IS LARGER THAN RECEIVER NOISE  AND IT SEPARATES ONE MOVING TARGET FROM OTHER MOVING TARGETS OR FROM CLUTTER ECHOES 4HE  DETECTION DECISION IS MADE AT THE OUTPUT OF THE RECEIVER  SO A TARGET  IS DECLARED TO BE PRESENT WHEN THE RECEIVER OUTPUT EXCEEDS A PREDETERMINED THRESHOLD )F THE THRESHOLD IS SET TOO LOW  THE RECEIVER NOISE CAN CAUSE EXCESSIVE FALSE ALARMS )F THE THRESHOLD IS SET TOO HIGH  DETECTIONS OF SOME TARGETS MIGHT BE MISSED THAT WOULD OTHERWISE HAVE BEEN DETECTED 4HE CRITERION FOR DETERMINING THE  LEVEL OF THE DECISION  THRESHOLD IS TO SET THE THRESHOLD SO IT PRODUCES AN ACCEPTABLE PREDETERMINED AVERAGE RATE OF FALSE ALARMS DUE TO RECEIVER NOISE !FTER THE DETECTION DECISION IS MADE  THE TRACK OF A TARGET CAN BE DETERMINED  WHERE  A TRACK IS THE LOCUS OF TAR GET LOCATIONS MEASURED OVER TIME 4H IS IS AN EXAMPLE OF  DATA  PROCESSING 4HE PROCESSED TARGET DETECTION INFORMATION OR ITS TRACK MIGHT BE DISPLAYED TO AN OPERATOR OR THE DETECTION INFORMATION MIGHT BE USED TO AUTOMATICALLY GUIDE A &)'52%  "LOCK DIAGRAM OF A SIMPLE RADAR EMPLOYING A POWER AMPLIFIER AS THE TRANSMITTER IN THE UPPER  PORTION OF THE FIGURE AND A SUPERHETERODYNE RECEIVER IN THE LOWER PORTION OF THE FIGURE                           
 With the multiple frequency radar  procedure it is possible to achieve a  fundamentally higher maximum reach,  equal probability of detection and equal  false alarm rate. That is, if th e probability  of detection and the false alarm rate are  equal in both systems, then by using two  or more frequencies it is possible to  achieve a higher maximum range. The  smoothing of the fluctuation of the  complex echo signal is the physical basis  for thi s. 
 OF 
 FIELD POLARIZATION ORIENTED AT  O 4HE  ENERGY IN THE COUPLER CONTAINS BOTH DIFFERENCE SIGNALS COUPLED AS THE COSINE AND SINE OF THE ANGULAR POSITION OF THE COUPLER   V ST  WHERE VS IS THE ANGULAR RATE   OF ROTATION 4HE HYBRID ADDS THE COMBINED DIFFERENCE SIGNALS  $ AT THE ANGULAR  . 
 2.17  Evaluation of Probab ilities  ..................................  2.18  Detector Laws  ...................................................  2.23  Curves for Visual Detection  ................................ 
 906, 1973. 47. P. 
 ULES  WHICH  ALONG WITH POWER COMBINING  PREDRIVERS  DRIVERS  AND CONTROL CIRCUITRY  WERE HOUSED IN THREE SEPARATE CABINETS 4HERE WERE  FINAL POWER OUTPUT MODULES ARRANGED IN TWO GROUPS OF  %ACH MODULE &IGURE   PRODUCED  7 PEAK AND  7 AVERAGE FOR A  
 Trebits, R. N., R. D. 
  
 OF 
 27.Cpp. 1 138- 1 147, November, 1970.  107. 
 Ifweassume the beacon toreinterrogated forallangular positions oftheantmma ofthe interrogator and the sensitivity ofthe receiver tobekept constant, theangular width ofthebeacon arconthe PPI tube \rillvaryas didthe sector ofinterrogation inthe previous case. Overa large distance the reply arcwill beoftheorder ofmagnitude ofthehalf-po\rer bcam\ridth of the receiving antenna. For close-in beacons, extensions attributable to side lobes appear, and forvcry close beacons acomplete circle isobtained, The complete circle orside-lobe pattern can bereduced tothenarro\r arc bysuitable reduction ofthe gain ofthe radar receiver, again \vith th(, loss ofmore distant beacons. 
 TAZLE 10.1.—AvEEAG~ AND PULSE POWER OUTPUTS OF MICROWAVE MAGNETRONS RMA type No 4J21 4J73 725 3J21Frequency, McIsec 1,180 3,100 9,400 24,000Maximum average power output, w Soo 600 80 25Pulse power output, kw 800 1000 80 5.5hlaximum pulse length, psec 6,0 2.5 2.5 0.5 Efiency.-The purpose ofamagnetron istoconvert d-cpower into a-cpower atvery high frequencies. Magnetrons can perform this con- version with anefficiency ashigh as85percent, which compares favorably with the efficiency ofd-cto60-cps a-cconverters. Magnetron efficien- cies customarily liebetween 30and 50percent. 
      
 This is difficult to achieve without exciting  harmful surface waves when scanning. Nevertheless, matching with octave band - width for scanning to ±60° has been achieved. Limited Scanning.28 If scanning is limited to a small angular volume, considerable  simplifications become possible. 
 Luneburg lenses are sphe rical objects made from individual dielectric shells, whose  refractive index n from outside inward is in accordance with the function:   € n=2−r R0        2 R0=outer radius  (11.23) . Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 106       These Luneburg lenses have the property to concentrate an incoming wave at a point of t he  opposite outer side.  If one mounts a reflector there then the signal will be completely reflected in the incident direction. 
 M., and D. H. Archer: A Toroidal Microwave Reflector, IRE NatI. 
 The amount of differential phase shift depends on the ferrite material and the length of the  toroid. A digital latching phase shifter is obtaineci by placing in cascade a niirnber of separate  toroids of varying length. The lengths of each toroid are selected to provide a differential phase  shift of 180". 
 7, pp. 88-91, March, 1964.  I I. 
 Warner: Weather Effects on Radar, chap. 24 of" Radar Hand-  hook." M. I. 
 ch22.indd   25 12/17/07   3:02:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 
 ch01.indd   6 11/30/07   4:33:39 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 
 With ele c- tromagnetic waves the necessary delay times within the µs - ms range cannot to be reached.   Instead one converts the signal into an acoustic wave and thereby achieves a larger delay time  around a factor of 105.  For some years digital delay methods have been used in addition to the  analog methods. 
 Randall, of Birming-  ham, produced the first workable directly excited cavity  magnetron, the new and revolutionary type of valve for  generating these extremely high frequencies. Randall’s  “cavity magnetron was the first high-power generator of  centimetric waves in the world, and the magnetron is  likely for many years to remain the heart of every  modern radar equipment.  II2  . 
 MATIONS RESULTING IN AN IMPERFECT CALCULATION OF THE TRACKING ACCURACY 7HEN PREDICTION TIMES ARE LONG ANDOR WHEN VERY ACCURATE RESULTS ARE NEEDED  THESE IMPERFECTIONS IN THE +ALMAN FILTER COVARIANCE CALCULATION CAN BE SIGNIFICANT  AND THE TRACKING ERRORS CAN BE QUITE NON 
 582–590, September 1964. 69. M. 
 Exceptfortheaprioriweighting factorp(SN),Eq.(10.26)showsthatthemostprobable waveform Sj(t)istheonewhichhastheleast-mean-square deviation fromthereceived waveform y(t}. Thecomputation oftheaposteriori probability mightbeaccomplished bycomputing the cross-correlation function between theactualwaveform andthevariouspossible waveforms thatmightbereceived. Expanding theintegral inEq.(10.26)weget f[y(t)-Sj(t)]2dt=fy2(t)dt-2fy(t)s/(t)dt+fsf(t)de (10.27) Uponreception, thewaveform y(t)isknown,sothatthefirstintegralontheright-hand sideof theequation isconstant andcanbeabsorbed intheconstant k.ThelastintegralistheenergyE contained withinthesignalSj(t)andalsoisaconstant. 
 (U.S.S.R.), vol. 23, October 1978. 67. 
 It becomes nearly horizontal when the off-nadir point­ ing angle equals the antenna one-way 3-decibel beam­ width (Fig. 6). Because the tracker bases the half-power  point on the average signal in the plateau region, cor­ rected for antenna pattern decay, the result is a shift in  the null point of the closed-loop height tracker. 
 The antenna of the S-band Airport Surveillance Radar (ASR) of the ANlTPN-19 landing  system is shown in Fig. 7.25. The 14 ft (4.3 m) by 8 ft (2.4 m) reflector is an offset paraboloid  fed from a 12-element vertical line-source. 
 Only monostatic radars will be considered. PRFs.  Pulsed radars that employ doppler are divided into three broad PRF cat - egories: low, medium, and high. 
 HORIZON RADAR v .AVAL 2ES ,AB -EMO 2EPT   -AY   * *ONES AND 0 "ROWN  h3PORADIC METEOR RADIANT DISTRIBUTIONS ORBITAL SURVEY RESULTS v  -ON .OT  2OY !STR 3OC  VOL   PP n 
 A degradation of 3 dB is sometimes assumed when no other information is  available.  Cllher loss factors. A radar designed to discriminate between moving targets and stationary  objects (MTI radar) may introduce additional loss over a radar without this facility. 
 Thus when precipitation is of concern, the lower frequencies are to be  preferred. , < A1 the higher microwave frequencies, precipitation clutter can be reduced by meanh of '  high resolution in range and in angle. Since rain is relatively uniform, the statistics of thc  backscatter are described by the Rayleigh probability density function, even when the radar 1s  of high resolution. 
 UCT OF THE AZIMUTH AND ELEVATION ANGLES  !S LONG AS THE BEAMWIDTHS OF THE RADAR IN AZIMUTH AND ELEVATION  ARE SMALLER THAN  THE REGION TO BE SURVEILLED  THIS EQUATION IS NOT DIRECTLY DEPENDENT UPON FREQUENCY  (OWEVER  KEY PARAMETERS IN THIS EQUATION ARE DEPENDENT UPON FREQUENCY 0ARTICULARLY  PROPAGATION LOSSES FOR LOW ALTITUDE TARGETS AND TARGET 2#3 FOR SOME TARGET TYPES  ARE GENERALLY ADVANTAGEOUS FOR LOWER FREQUENCIES 4HE RESULT IS THAT !%7 SYSTEMS HAVE BEEN DEVELOPED AT 5(&  , BAND  AND 3 BAND FREQUENCIES !IRBORNE -4) RADAR SYSTEMS HAVE ALSO  BEEN UTILIZED TO ACQUIRE AND TRACK TARGETS IN  INTERCEPTOR FIRE CONTROL SYSTEMS )N THIS APPLICATION  THE SYSTEMS HAVE TO DISCRIMINATE AGAINST CLUTTER ONLY IN THE VICINITY OF A PRESCRIBED TARGET 4HIS ALLOWS THE SYSTEM TO BE OPTIMIZED AT THE RANGE AND ANGULAR SECTOR WHERE THE TARGET IS LOCATED -4) IS ALSO USED TO DETECT MOVING GROUND VEHICLES BY RECONNAISSANCE AND TACTICAL FIGHTER AIRCRAFT 4HE ENVIRONMENT OF HIGH PLATFORM ALTITUDE  MOBILITY  AND SPEED  COUPLED WITH  RESTRICTIONS ON SIZE  WEIGHT  AND POWER CONSUMPTION  PRESENT A UNIQUE SET OF PROBLEMS TO THE DESIGNER OF AIRBORNE -4) SYSTEMS 4HIS CHAPTER WILL BE DEVOTED TO CONSIDER 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.696x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 the predicted distribution of the resultant radar cross section when multipath and  Faraday rotation are taken into account. The relevant physics—rough surface forward  scattering coefficient, bistatic (in the vertical plane) free-space target scattering cross 6000 5000 4000Range (km)30008 2000 10000 6 12 Time of Day (local)18 2410 18 20 20 20 26 24 22 20 18 16 14 1212 10 8 8 8 6 FIGURE 20.38  Range-time map of optimum frequency in MHz to detect a specific target, as a  function of range and time-of-day, for a particular month and level of solar activity 20,000 SAMPLES TARGET: TYPE 1MEAN: 21.5 SDEV : 8.0 MED  : 23.0 MAX  : 37.0 10%   : 10.0 90%   : 30.0 PEAK : 26.0 FREQ : 25.0 ELEV : 5.0 −50−40−30−20−10 0 RCS (dbsqm)10 20 30 40 50030060090012001500FREQUENCY OF OCCURRENCE FIGURE 20.39  Predicted distribution of effective RCS for the Aermacchi MB326H trainer jet  aircraft viewed nose-on at a height of 1000 feet when ground-reflection multipath and Faraday rota - tion are taken into account. 
 TION  )N THE FOLLOWING  THE APPLICATIONS USUALLY FOUND IN THE VARIOUS RADAR BANDS ARE BRIEFLY INDICATED 4HE DIFFERENCES BETWEEN ADJACENT BANDS  HOWEVER  ARE SELDOM SHARP IN PRACTICE  AND OVERLAP IN CHARACTERISTICS BETWEEN ADJACENT BANDS IS LIKELY    4HE WAVELENGTHS OF +A BAND RANGE FROM  MM TO  MM  WHICH QUALIFIES THEM UNDER THE hLEGALv DEFINITION OF  MILLIMETERS  BUT JUST BARELY . 
 In practice, it makes little difference which of the  two detector laws is used. The difference between the square-law and the linear detectors was  shown by Mar~um~~ to produce less than 0.2 dB difference in the required signal-to-noise  ratio. If one has a choice, the linear law might be preferred because of its linearity and, hence,  its large dynamic range. 
 SURVEILLANCE RADAR BUILT AND TESTED AT THE .AVAL 2ESEARCH ,ABORATORY 53   3ENRAD WAS AN EXAMPLE OF HOW TO BUILD A RADAR SO AS  TO FORCE THE JAMMER TO DILUTE ITS RADIATED ENERGY PER UNIT BANDWIDTH IT INCLUDES BOTH FREQUENCY AGILITY AND FREQUENCY DIVERSITY 4HIS RADAR SHOWS THAT ITS UNUSUALLY WIDE BANDWIDTH ALLOWS A REDUCTION OF THE EFFECTIVENESS OF THE NOISE  JAMMER THAT CAN SERI 
 Phased arrays may be in the form of lens arrays or reflec - tarrays, as shown in Figure 13.30, where an optical-feed system provides the proper  aperture illumination. The lens has input and output radiators coupled by phase shift - ers. Both surfaces of the lens require matching. 
 HORIZON RADARS 4HE MAIN DESIGN PRINCIPLES EG  SELECTION OF TRANSMITTER POWER  FREQUENCY  WAVEFORM  AND ANTENNA GAIN  AS DICTATED BY THE %#- THREAT ARE ALSO DISCUSSED IN SOME DETAIL#HAPTER     ! LIST OF ACRONYMS IS AT THE END OF THE CHAPTER BEFORE THE LIST OF REFERENCES. Ó{°Ó  2!$!2 (!.$"//+  4HE CHAPTER ENDS WITH AN APPROACH TO THE PROBLEM OF EVALUATING THE EFFICACY OF  %##- AND %#- TECHNIQUES 3ECTION   4HERE IS A LACK OF THEORY TO PROPERLY QUAN 
 Plan-position Indicator.-As has been indicated inearlier sections (e.g.,Sec. 12”2), PPI displays can beproduced byany ofseveral methods, which, ingeneral, may beclassified under three principal headings. 1.The rotating-coil method, inwhich the range-sweep current is passed through acoil which isrotated about the tube neck in synchronism with the antenna motion. 
 BAND WAVELENGTH  AND EXTENSIVE POLARI 
 It does have ambiguities in the doppler domain that result in  so-called blind speeds. Pulse doppler radar . There are two types of pulse doppler radars that employ either  a high or medium PRF pulse radar. 
 POWER LINEAR 
 RADAR RECEIVERS  6.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 in the subsequent digital signal processing. Most radars transmit multiple pulses at  a target before the antenna beam is moved to a different direction, and the multiple  returns are combined in some fashion. The returns may be combined using coherent  integration or various doppler processing techniques (including MTI) to separate  desired targets from clutter. 
 Lett. 2015 ,12, 1576–1580. [ CrossRef ] 12. 
 The radar echo from land depends on the  type of terrain. as described by its roughness and dielectric properties. Desert, forests. 
 129–132. 12. Li, J.; Stoica, P . 
 REFLECTOR TARGET 4HE ANGLE NOISE PHENOMENON AFFECTS ALL TYPES OF TRACKING RADARS BUT IS MAINLY OF  CONCERN FOR TRACKING RADARS WHERE PRECISION TARGET LOCATION IS NEEDED 4O AID IN VISU 
 57. Wilson, J. W., and E. 
 ERATIVE 46 OR &- STATION OPERATOR WOULD NOT BE INCLINED TO hCOOPERATEv WITH A 0"2 BY ALTERING ANTENNA COVERAGE OR MODIFYING BROADCAST MATERIAL WITH SPECIAL WAVEFORMS &URTHERMORE  THERE IS ALWAYS THE POSSIBILITY OF A TRANSMITTER FAILURE IN THE COURSE OF NORMAL OPERATIONS OR FROM AN ENEMY ATTACK 4HIS EVENT WILL DEGRADE PERFORMANCE OF A 0"2 THAT OPERATES WITH MULTIPLE TRANSMITTERS AND ELIMINATE PERFORMANCE OF A 0"2 THAT OPERATES ONLY WITH THAT TRANSMITTER !S A RESULT  THE 0"2 IS FREE TO EXPLOIT COOPERATIVE OR NONCOOPERATIVE  TRANSMISSIONS IF THEY ARE SUITABLE HOWEVER  COMMERCE CONTROLS THEIR OPERATION WITH THE 0"2 REMAINING A USER OF OPPORTUNITY  SPECIFICALLY SUFFERING NONOPTIMUM WAVEFORMS 3ECTION    LIMITED ELEVATION COVERAGE  AND OCCASIONALLY REDUCED OR DENIED PERFORMANCE #ONSTRAINTS ALSO APPLY WHEN A HITCHHIKER ATTEMPTS TO EXPLOIT A  COOPERATIVE OR NON 
 LINE )N A HIGH 
 whereIi¢isthephasedifference inserted between adjacent elements. Amplifiers maybeplacedbetween theindividual antenna elements andthebeam­ forming (phase-shifting) networks toamplify theincoming signalandcompensate forany lossesinthebeam-forming networks. Theoutputofeachamplifier issubdivided intoanumber ofindependent signalswhichareindividually processed asiftheywerefromseparate receivers. 
 Also, examination suggests that a denser distribution of data collection sites would improve the data. It would be very useful to have noise source maps so that antenna patterns and explicit propagation effects could be taken into ac- count. Some work toward source maps has been done by Ortenburger and Kramer,39 but there is no known generally available database in this form. 
 28, no. 3, pp. 513–525, July 2003. 
 ,  P10R4, AMS, Albuquerque, 2006. 155. R. 
 BEAM PEAK   4HE PRICE  THAT MUST BE PAID TO ACHIEVE THESE LOW SIDELOBES INCLUDES   A REDUCTION IN GAIN    AN INCREASE IN BEAMWIDTH    INCREASED TOLERANCE CONTROL    INC REASED COST  AND   THE  NEED TO OPERATE IN AN ENVIRONMENT FREE FROM OBSTRUCTIONS THAT CAN READILY INCREASE THE SIDELOBES  )N SPITE OF THESE DRAWBACKS  THE TREND TO LOW 
 set.The unfavorable signal-to-noise characteristics ofthe C-scope are thus sonmvhat mitigated, and the C-scope, ~vhich isrepeated forthe benefit ofthe pilot, displays only the dr>ired target. .~range meter operated bythe position oftheradar operator’< mo~-able marlier isalso pro~-ided toenable thepilot togauge theprogress oftheinterception. The SCR-720 has been used with success lmth bythe R.IF and the .\.\F. 
 16.21 CPCT concept showing displacement of the phase center (a) behind the physical aperture and (b) ahead of the phys- ical aperture. (Courtesy of Hazeltine Inc.15)APERTUREPHASE DISTRIBUTION AMPLITUDE DISTRIBUTION PHASE CENTERVIRTUAL EXCITATION FAR-FIELDWAVEFRONT (a) APERTURE AMPLITUDEDISTRIBUTION PHASE DISTRIBUTION . form. 
 The average gain  (S,,/S,):,,., of tlic sitiglc dclay-litlc-caricclcr. can hc sllown to be eqrlal to 2. Therefore. 
 Currents flow across thejunction between therotating and nonrotating parts ofthe round tube bymeans ofthe same folded choke arrangement used forthe outer conductor ofthe coaxial rotary joint described inSec. 11.2. Figure 11.13 shows atypical joint. 
 K ros1czynsk y. J.: Efficiency of the Two-Frequency MTI System, Tlte Radio and Electronic Engineer.  vol. 
 Many topics, such as electronic countermeasures, will have to be omitted. This chapter should be considered a status report on the new frontier for radar systems. A more comprehensive treatment of SBR can be found in "Spacebased Radar Handbook," written and edited by the author and published by Artech House. 
 Sensors 2019 ,19, 252 The radiating elements are stacked microstrip patch antennas with the same design of the transmitting one. The total gain of the module including the LNA gain and transmission line losses is 13.6 dB. 4. 
 Planform  outline has been added for clarity. ( Courtesy D. L. 
 (ed.): "Microwave Receivers," MIT Radiation Laboratory Series, vol. 23,  McGraw-Hill Book Company, New York, 1948.  5. 
 Also, the effect of snow on electromagnetic propagation is less than with water. Wet snow can  stick to the radome and its high liquid-water content can adversely affect propagation. The  rernoval of snow by thermal means (heaters) is generally quite expensive. 
 Each object, which is acquired from mo v- ing Radar, delivers a defined progression of the Doppler frequency.  From this the aspect angle  0θ, the velocity of movements, the height h, and the range R are determined.  Figure 9.4  shows the associated array of curves. 
  HAD A DIFFERENT MISSION THAN THE & 
 Tech. Rept. 1965-3, November 1967. 
 Purves. C. G.: Geophysical Aspects or Atmospheric Refraction, Nai,al Research Laboratory, Washing­ ton. 
 5. Discussion In this part, we will evaluate the imaging performance of the KA-DBS algorithm with the other imaging algorithms under di ﬀerent CPI lengths. To estimate the imaging quality, entropy is always utilized, which can be deﬁned as [ 8]: E=−M⎭summationdisplay m=1N⎭summationdisplay n=1pm,nlog(pm,n) (34) where the probability distribution function is: pm,n=I2 m,n M⎭summationtext m=1N⎭summationtext n=1I2m,n(35) In Equation (35), Im,n(m=1,2,...,M, n=1,2,...,N) is the concerned image, which is an M×Nmatrix. 
 vol. 19. pp. 
 DOPPLER PLANE TO UNCOVER PREVIOUSLY OBSCURED TARGET ECHOES !ND PERHAPS MOST IMPORTANTLY  IN THE CONGESTED (& SPECTRUM WHERE CLEAR CHANNELS OF ADEQUATE BANDWIDTH TO ACHIEVE THE DESIRED RESOLUTION MAY BE SCARCE  &- 
 The azimuth impulse responses of the chosen strong scatterer based on the IMAM method and the EMAM method. 64. Sensors 2019 ,19, 213 Figure 13shows the estimation curves of the spatially-variant Doppler parameters based on the different methods. 
 E. Brennan: Cumulative Probability of Detection for Targets Approaching a  Uniformly Scanning Search Radar, Proc. IEEE, vol. 
 H. 10, results in a phase shifter with a fast switching time and with less  drive power than required of a Reggia-Spencer device. Furthermore, it is not as temperature  sensitive. 
 Detailed RecommendationsAll future ASV equipment should aim at ful ﬁlling the following requirements: (a) (i) It is essential to afford location in plan in all forward directions and it is desirable to afford such location in all directions. (ii) PPI or other appropriate map type presentation should be used, and a pilot ’s indicator of appropriate characteristic incorporated in the installation. (b) Maximum ranges from aircraft at 1,000 ft should be not less than: (i) Against submarine, conning tower only 10 miles (ii) Against submarine awash 20 miles(iii) Against a single ship of 1,000 tons 20 miles(iv) Against battleships 40 miles(v) Against E-boats (aircraft at 500 ft) 10 miles(vi) Against aircraft 8 miles (c) Beacons should be readable up to ranges of at least 100 miles. 
 POWER RADAR v 0ROC )%%%  PP n  !PRIL    4 4 4AYLOR  h$ESIGN OF LINE 
 Two different models were developed based on the same data, one a  linear model and one a more complicated formulation. Here we present only the  linear model. These models are for averages , and the models do not include varia - tions about the average. 
 !   
 WINDOW INTEGRATOR SHOULD BE USED )F THE NUMBER OF PULSES IS LARGE GREATER THAN    A BATCH PROCESSOR SHOULD BE USED )F THE SAMPLES ARE INDEPENDENT  A ONE 
 The signal from the previous  transmission, which is delayed by a time T = pulse repetition interval, is  Vz = k sin [2n&(t - T) -  Everything else is assumed to.remain essentially constant over the interval T so that k is the  same for both pulses. The output from the subtractor is  V= V, - V2 =2k sin nfdTcos 2n& t -- I ( :)-+,I  It is assumed that the gain through the delay-line canceler is unity. The output from ttie  canceler [Eq. 
 Receiver filters are assumed to have no memory from one transmission to the next; their response is to a single transmission. Actually, most radars direct a multiplicity of pulse transmissions at a target before the antenna beam is moved to a different direction, and the multiplicity of echoes received is combined in some fashion. The echoes may be processed by an integrator, which is analogous to a matched filter in that ideally its impulse response should match the echo modulation produced by the scanning antenna. 
 si(ta)=rect/parenleftbiggta−tac,i Ts/3/parenrightbigg exp/parenleftBig j2πfdcta+jπedrt2 a+jπe3rdt3 a/parenrightBig , (4) where tac,iis the azimuth time for the center of each sub-segment and can be expressed as follows. tac,i=−Ts 3+(i−1)Ts 3, i=1, 2, 3. (5) The data in (4) can be translated to the position where ta=0 and tais replaced by ta+tac,i. 
 MULTIPLEXED ACROSS THE  MULTIBEAMS /NE 230 STEPS ACROSS THE EVEN 
 TOPPED PORTION OF THE PULSE RETAINS THE HIGH TRANSMITTER EFFICIENCY FOR MOST OF THE PULSE  DURATION 3INCE A RECTANGULAR PULSE HAS THE BEST TRANSMITTER EFFICIENCY BUT HAS HIGH  SPECTRAL ENERGY AT FREQUENCIES FAR FROM THE CENTER FREQUENCY  WHEREAS A HIGHLY SHAPED PULSE HAS LESS FAR 
 LANCE 4HE UPDATE RATE FOR HIGH PRIORITY TRACKS SHOULD BE SUCH THAT A SINGLE TRACKING DWELL IS SUFFICIENT TO UPDATE THE TRACK 4HE ACTUAL UPDATE RATE WILL DEPEND ON MANY FACTORS INCLUD 
 TO 
 ££°£ä  2!$!2 (!.$"//+  REPRESENTATIVE OF A SOLID 
 POLARIZED RETURNS SHOULD SHOW A STRONG DEPENDENCE ON BOTH  THE RAIN RATE AND THE DROP 
 DETECTION SPECTRUM IS THE SELF 
 The first sidelobe of the filters described by Eq. (4.16)  llas a valire of - 13.2 dB with respect to the peak response of the filter. If this is too high for  proper clutter rejection, it tnay be reduced at the expense of wider bandwidth by applying  arnpliti~de weights \sti. 
 A matched-filter SAW pulse compression device can use variable finger lengths to  achieve frequency weighting, and this internal weighting can correct for the Fresnel  amplitude ripples11 in the FM spectrum. With this correction, –43 dB time sidelobe  levels can be achieved for a linear-FM waveform with TB as low as 15. The level of  sidelobe suppression depends upon the time bandwidth product, the weighting func - tion applied, and fabrication errors in the SAW device. 
 RESENT SPECTRAL 
 /\ minimum of four pulses are usually necessary with  the conical-scan radar. However, a continuous-tracking radar seldom makes a measurement  011 a single pulse. (Phased-army radars and some surveillance radars, however, might use the  monopulse principle to extract an angle measurement on the basis of a single pulse.) In  practice. 
 POLAR CONTENT OF THE  RECEIVED RADAR SIGNAL MAY BE OF BENEFIT TO MARINE OPERATIONS WHERE SEA ICE IS A HAZARD $UE TO STRUCTURAL CHANGES THAT OCCUR IN OLDER ICE THAT AFFECT THE REFLECTION OF RADAR ENERGY  IT IS POSSIBLE TO DIFFERENTIATE BETWEEN POTENTIALLY DANGEROUS OLD ICE  INCLUDING GLACIAL ICE ICEBERGS   AND SINGLE 
 The detectior~ of't~rrairt ,/?afrrres such as hills and mountains ahead of an aircraft to warn of  approaching Iligh ground (tr~r~.uiu c~t~)idatrcc) or to allow the aircraft to follow the co~~tour  of t l~e land (terrait1 .fbllo\t~i~rg).  ilinppirrg. or imagirrg, radars that irtilize high resolution. 
 ~The over-all bandwidth ofa radar receiver may bedetermined bythebandwidth ofeither the i-for the video circuits. However, forthe purposes ofthis chapter weneed only beconcerned with the i-famplifier, since weareinterested here in questions ofstability rather than inthe quality ofsignals. Asdic- tated bytheprinciples outlined inSec. 
  
 D. Mallett, and I. S. 
 E. Brennan and I. S. 
 AP-17, pp. 363-365, May. 1969. 
 345–425. 77. W. 
 These single-mode, simply flared horns suffice for pencil-beam antennas with just one linear polarization. When more demanding antenna performance is required, such as polarization diversity, multiple beams, high beam efficiency, or ultralow sidelobes, the feeds become correspondingly more complex. For such antennas segmented, finned, multimode, and/or corrugated horns are used. 
 VIII, fitted to Beaufighters of Coastal Command.ASV Mk. XVI Radar range-finder used by Coastal Command strike aircraft. ASV Mk. 
 RIORATES PROGRESSIVELY AS THE ANGLE OF INCIDENCE MOVES AWAY FROM NORMAL INCIDENCE )T IS DIFFICULT TO OVERCOME THE FRAGILITY PROBLEM WITH ROBUST MATERIALS  BUT THE BAND 
 Aninductance with aspecial alloy core may beplaced between points A’A(Fig. 10.36). This device has the property ofFixed spark points possessing ahigh inductance when thecurrent through itissmall, and A’~b N avery lowinductance when thecur- rent islarge. 
 POLARIZED RESPONSE ¾3," SIDELOBE BLANKING  ¾ ¾3,# SIDELOBE CANCELER  ¾%LECTRONIC SCAN ¾ ¾ ¾!DAPTIVE RECEIVE POLARIZATION ¾#ROSS POLARIZATION CANCELLATION ¾ 4RANSMITTER  RELATED,OW CROSS 
 4 ). Most of the basic MTI concepts that have been added were known at the time of the  first edition, but they had not appeared in the open literature nor were they widely used in  practice. Inclusion in the first edition would have.been largely academic since the analog  delay-line technology available at that time did not make it practical to build the sophisticated  signal processors that were theoretically possible. 
 Fortunately, solid-state module reliability has proved to be even better than the MIL-HDBK-217 predictions; AN/FPS-115 (PAVE PAWS), for example, actual transceiver module MTBF, including the receiver transmit/receiver (TIR) switches and phase shifters as well as the power amplifiers, has grown to 141,000 h, which is 2.3 times the predicted value. In fact, MTBF for the output power transistors measures better than 1.1 million h.2 5.2 SOLID-STATE MICROWAVE POWER GENERATION Although the RF power-generating capability of single solid-state devices is small with respect to the overall peak and average power requirements of a radar trans- mitter, solid-state devices can be used quite effectively. Large peak and average powers can be attained by combining the outputs of hundreds or thousands of identical solid-state amplifiers. 
 16.5] STABILITY REQUIREMENTS 641 echoes tobeat inamplitude intheregion ofoverlap, even when nocoher- entreference signal ispresent. Since theexpression forthephase shift is identical with theprevious expression, Eq. (4)also applies here. 
 Hence,   vRvy x y hr= ⋅ = + +vR 2 2 2  where vr is the relative speed. Curves of constant relative speed are also curves of  constant doppler shift. The equation of such a curve is  x yv v vhr r2 22 2 220 −−+ =   This is a hyperbola. 
 RESPOND TO THE SAME POINTS ON THE )& SIGNAL INPUTS TIME LINE  SINCE THE ) AND 1 SAMPLES WERE DERIVED FROM ALTERNATE !$# SAMPLES (OWEVER  THE 1 FILTER  WITH ALTERNATE COEF 
 Deployable Antenna Flight Experiment Definition Study: Mid-Term Review, Grumman Aerospace Corporation, 7VAS-8-33932, Mar. 20, '981. 49. 
  
 Markus, “A hybrid (Finite Difference-surface Green’s Function) method for computing  transmission losses in an inhomogeneous atmosphere over irregular terrain,” IEEE Transactions  on Antennas and Propagation , vol. 40. no.12, p. 
 11 . .1. It can be shown that the theoretical rms range error is  C c5R = ----- -----. 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.4  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 where G is the universal gravity constant‡ 6.67 × 10–11 Nm2kg–2. Table 18.1 lists rep - resentative spacecraft velocities for bodies in the solar system that have been visited,  or are likely to be observed, by range-doppler radars. 
 TO 
 Third, reset the RCS amplitudes under T=μ+2σto 0. Here, we use double the standard deviation σto ensure that the threshold value is higher than most of the noise. The red line shown in Figure 6c represents T=μ+2σ=0.1362. 
 1619 that atarget moving inthe clutter produces aresultant echo that varies inboth amplitude and phase. Todetect theamplitude variations, allthat isrequired isareceiver that does not limit—that is,one with a linear-logarithmic response. Since nocoherent reference oscillator is used, this iscalled thenoncoherent method ofdetecting moving targets. 
 Where air - borne radars are used for altimeters or mapping, other aircraft are undesired targets, and  the ground is the desired target. In the case of weather radars, ground, buildings, and  aircraft are clutter, and rain or snow is the desired target. More commonly, radars are  intended for detection of aircraft, missiles, ships, surface vehicles, or personnel, and the  reflection from weather, sea, or ground is classified as clutter interference. 
 S.: Optiriial I'rackirig of Maneuvering Targets, IEEE Trans., vol. AES-9, pp. 512-519, July,  1973. 
 However, for purposes of analysis, most fluctuating clutter targets may be represented by a  model consisting of many independent scatterers located within the resolution cell of the radar.  The echo at the radar receiver is the vector sum of the echo signals received from each of the  individual scatters; that is, the relative phase as well as the amplitude from each scatterer  influences the resultant composite signal. If the individual scatters remain fixed from pulse to  pulse, the resultant echo signal will also remain fixed. 
 2003 ,22, 95–99. 49. Chen, Z.; Chen, S.; Lisheng, W.U. 
 These types of  interfering signals  can jam or redu ce the effectiveness of a  radar. When searching for p ulsed or interfering signals, an RF  analyzer must not “blink” when the signal appears.  Discovering, triggering, and capturing infrequent signals or  transient characteristics of signals are required befor e  analysis can be performed. 
 24–35,   October 1977. 12. K. 
 14. This  is the normal method of con-  necting a valve amplifier. The  signal is applied to the grid, and  a resistance (or inductive) load is  = in the anode circuit, so the ouptut  is taken direct from the anode. 
 Bur. Stds .. vol. 
 A chapter in the first edition of this handbook was devoted to this approach, which since then has received much less attention; fre- quency is usually considered too important a parameter to give up for scanning. IF Scanning. For receiving, the output from each radiating element may be heterodyned (mixed) to an intermediate frequency (IF). 
 26. Thor, R. C.: A Large Time-bandwidth Product Pulse-Compression Technique, IEEE Trans., vol. 
 CLUTTER IMPROVEMENT CAN BE DEFINED BY AVERAGING ALL FILTERS  OVER ITS RESPECTIVE RANGE OF TARGET DOPPLERS   )FF#! ' F DF #! ' F .# FF # F 3#2 
 Timmoneri, “Maximum likelihood estimate of target angular  coordinates under main beam interference: Application to recorded live data,” in Advances in  Direction-of-Arrival Estimation , S. Chandran (ed.), Norwood, MA: Artech House, Inc., 2006,  pp. 285–303. 
 69. Probert-Jones, J. R.: The Radar Equation in Meteorology. 
 c-30Q U <1l '"enen-40-~u -50-- -60UHF 1000L Frequency. (MHz) (b)c X10,000 Fi~ure13.11Medi<lnvaluesofaOasafunction offrequency. Grazing angle=8°.(a)Verticalpolarization. 
  INDEPENDENT TIME 
 Dareff, and J. J. Schanne, Jr.,  “Polarimetric X/L/C-band SAR,” in Proceedings of the 1988 IEEE National Radar Conference ,  1988, pp. 
 APERTURE PRODUCT IS NEVER AS LARGE AS DESIRED 4HE FORWARD PROJECTED AREA AS WELL AS AVIONICS WEIGHT IS VERY COSTLY IN MOST FIGHTER AIRCRAFT PARAMETERS 4HESE PARAMETERS HAVE MOTIVATED USERS  BUYERS  AND DESIGNERS TO WANT MORE FUNCTIONS IN A SINGLE RADAR AND ITS COMPLEMENTARY PROCESSING SUITE !S A RESULT  MOST MODERN FIGHTER RADARS ARE MULTIFUNCTIO NALPROVIDING RADAR   NAVIGATION  LANDING AIDS  DATA LINK  AND %LECTRONIC #OUNTER -EASURES %#-  FUNC 
 R. Kramer Jr., and P. K. 
 Gabriel. W. F.: Adaptive Array Antennas for AEW Radar, Report of NRL Progress. 
 "AND 2ADAR 8"2   4HE NINE 
 PHIDE )N0   SILICON CARBIDE 3I#   GALLIUM NITRIDE 'A.   OR SILICON GERMANIUM 3I'E  3EMICONDUCTORS LIKE SILICON OR GALLIUM ARSENIDE HAVE FOUND EARLY WIDE ACCEPTANCE BECAUSE IT HAS PROVEN PRACTICAL TO CONTROL THEIR CRYSTAL LATTICE DEFECTS ACCURATELY AND REPEATABLY DURING TRANSISTOR MANUFACTURING 3OME SEMICONDUCTORS  SUCH AS GALLIUM NITRIDE 'A.  OR SILICON CARBIDE 3I#   ARE REFERRED TO AS WIDE BANDGAP SEMICONDUC 
 ERROR VOLTAGE 0HASES ARE ADJUSTED TO PROVIDE   OR  ON A POINT 
 The performance8 of this detector for n « 10 is only 0.5 dB worse than the optimal detector given by Eq. (8.3). The detection performance can be obtained by usingLINEARDETECTOR SQUARE-LAW DETECTOR FLUCTUATING NON FLUCTUATINGCOLLAPSING LOSS (dB) aV~N/0 . 
 Noise ultimately limitsthecapability ofanyradar.Theproblem ofextracting information fromthe received waveform isdescrihed inthenextchapter. Thedetection ofsignalsinthepresence of clutterisdiscussed inChap.13. (' 10.2MATCHED-FILTER RECEIVER18 Anetwork whosefrequency-response function maximizes theoutputpeak-signal-to-mean­ noise(power) ratioiscalledamatched filter.Thiscriterion, oritsequivalent, isusedforthe designofalmostallradarreceivers. 
 There arc at least three techniques which might he  used to minimize the effect of spherical aberration. One is to employ a reflector of sufficiently  large radius so that the portion of the sphere is a reasonable approximation to a  paraboloid. 30 32 The second approach is to compensate for the spherical aberration with  special feeds or correcting lenses.33·34 These techniques yield only slightly larger scan angles  than the single paraboloid renector with movable feed. 
 pp. 1492 1 F 01. August. 
 Liquidcooling iscmployed forboththeanodeandcathode, Approximately one gallonofwaterperminutewithapressure dropof9psiisrequired. Thetubeishousedina magnctically shielded package thatstandsapproximately 2fthighwithadiameter of1ftand weighs210lb.i\Vac-Ion vacuum pumpisincluded withinthemagnetically shielded package tomonitor thevacuum andtoprovide continuous pumping actionduringoperation. Inthe i\N/MPS-36transmitter chaintheSFD-257 ispreceded byanSFD-244 cathode-pulsed CFA withIIdBgain.whichisdrivenbya9041'1cathode-pulsed TWTwith49dBgain.Thedrive powertotheT.WTis50mW, 6.7C;IUD-CONTIH)LLED TUnES Theearlyradarsdeveloped duringthe1930susedconventional grid-controlled vacuum tubes sillcethereexisted 110othersourceoflargeRFpowcr.Thislimitcdthedcvelopment ofIhe earlyradarstotheVHFandthelowerUHFbands.Thesetubesweretriodesortetrodes designcd 10minimize thetransit-time effectsandotherproblems ofoperating atVHFand UHF.11Thepotential appliedtothecontrolgridofthetubeactsasagate,orvalve,tocontrol thenumber ofelectrons traveling fromthecathode totheanode,orplate.Thevariation of potential appliedtothegridisimparted tothecurrenttraveling totheanode.Theprocess by whichtheelectron streamismodulated inagrid-controlled tubetoproduce amplification is calleddellsitymodulatioll. 
 W. Morrow: The Fast Fourier Transform, IEEE Specrrum, vol. 4, pp. 
 The usual ground-based air surveillance radar that provides the range and azimuth of a target generally uses a mechanically rotated reflector antenna with a fan-shaped beam, narrow in azimuth and broad in elevation. Airborne radars and surface- based 3D air surveillance radars (those that rotate mechanically in azimuth to measure the azimuth angle but use some form of electronic steering or beamforming to obtain the elevation angle, as discussed in Chap. 20) often em- ploy planar array apertures. 
 Howard Locus, Inc., a subsidiary of Kaman Corp. 18.1 INTRODUCTION A typical tracking radar has a pencil beam to receive echoes from a single target and track the target in angle, range, and/or doppler. Its resolution cell—defined by its antenna beamwidth, transmitter pulse length, and/or doppler bandwidth— is usually small compared with that of a search radar and is used to exclude un- desired echoes or signals from other targets, clutter, and countermeasures. 
 Silicon power FETs have demonstrated power output characteristics comparable to the silicon bipolar transistor in the 0.1- to 1.0-GHz frequency range6; however, power FETs that are made from gallium arsenide (GaAs) are limited in power output capability, primarily because of the poor thermal conductivity of GaAs and lower typical breakdown voltages; but they are capable of much higher frequency operation than silicon devices.7 In addition, the GaAs FET can be utilized in a monolithic format, where the remaining passive circuitry of the amplifier is totally integrated on the same substrate with the active device. GaAs Power FETs. In an FET, the flow of charge carriers between the source and drain electrodes is modulated by one or more gate electrodes, and when the FET is operated as a power device, it may be considered as a simple current switch. 
 J. G. Schoenenberger and J. 
 TRACKING ERROR OF AN 3 
 The Energy of the Azimuth Mainlobe Must be Preserved From Equation (7), the azimuth signal is distributed in elevation. To preserve the energy of the azimuth mainlobe, the integrating range [−h,h]must contain the position of the azimuth mainlobe. This is distributed in space because a point target can occur anywhere within the resolution cell. 
  
 Unlike tubes, where the ratio of peak to average power capability can be very high, the peak power output capability of a transistor operated in a short-pulse low-duty mode may only be 2 to 3 times greater than the peak power capability when that device is operated CW. Thus, solid-state operation favors long pulse widths and high duty cycles. For retrofit systems, where high peak power from a short pulse width is required, the acquisition cost of a solid-state transmitter may be prohibitive. 
 DELAY BETWEEN THE PORTION IMPARTED  ON THE TRANSMIT AND THAT ON RECEIVE 4HE TIME 
 This method isused principally incases where thescan istoorapid fortherotating-coil method and theantenna issofaraway that thetransmission ofthe 1Insome cases a3-phase synchro isused, andtheresulting signals arepassed through aresistor network which reduces thethree phases totwo.. .-—Groundf —..J’l_f=l_lTrigger I I I(CT)Sawtooth~1r- (A)CRTswitching signal,~ ~ ,D),ridO,~’”&! switching%,,, JllTJ ‘“’’a’”””’”’ ‘!/U I_(B)Sawtooth generator ~ Trl~er I F==lI=kI offl-dwave,,.......,,..AA +-lIron.cored off.centermg co Sweepcoil <Scanner 1r Synchro ~ Iamp.VIII-l“w,l=. m ~ ,J , ,, ,V2.-% Irr Torange-1 AeRTblanking E markgenerator + +250v4 6AC7IV,IIJU 1, als v WwT%d I(a I 1 i%gger Torange~AI4 markgenerator FIG.13.44.—Rot8ting-coil PPI.a m$Y. 
 An analytic formulation and Monte Carlo computer simulation of the effects of phase errors for normally distributed random phase errors and for three cross- correlation functions have been given by Greene and Moller.6 Signal Processing. The preceding subsections have discussed a number of aspects of radar signal processing. Also discussed has been the radar system up to the point of signal processing. 
 As illustrated in Figure 17.5, the actual  ground locations that correspond to these range samples are not spaced at constant  intervals in ground range. Near the scene center, they are spaced at  dg ≅ dr / cos y (17.11) where y  is the grazing angle. At ground ranges closer to the radar, they are spaced still  farther apart because of the spherical range contours. 
 The Σ + ∆ and Σ – ∆ outputs each look like the output of a conical- scan tracker except that their modulation function differs by 180°. In case one  channel fails, the radar can be operated as a scan-on-receive-only conical-scan radar  with essentially the same performance as a conical-scan radar. The advantage of two  channels with opposite-sense angle-error information on one channel with respect to  the other is that signal amplitude fluctuations in the received signal are canceled in the  post-detection subtraction at the IF output that retrieves the angle-error information. 
 Except possibly for the details of the angle factor Fp, Eq. 15.16 is equiva - lent to the result obtained by the SPM discussed above, and although it is sometimes  felt that its derivation from a surface integral provides some potential for greater  generalization, it carries with it all of the same restrictions. Before proceeding further, it is instructive to look a little more closely at the impli - cations of the mathematical expressions in these formulations. 
 SHIFTED TARGET ECHOES CAN BE PRODUCED BY ION OSCILLATIONS !CCORDING TO ! ! !CKER   hTHESE ARE PERIODIC INSTABILITIES THAT CAN OCCUR IN THE ELECTRON BEAM  AT VIDEO FREQUENCIES  RESULTING IN SIGNALS OTHER THAN THE CARRIER FREQUENCY  CAUSING SEVERE PROBLEMS TO DOPPLER RADAR PERFORMANCEv !CKER ALSO STATES THAT ION OSCILLATIONS REQUIRE A FINITE TIME TO DEVELOP SO THAT IF A TUBE IS OPERATED WITH LESS THAN A  §S PULSE WIDTH  ION NOISE IS USUALLY NOT OF CONCERN !DVANCES IN DIGITAL TECHNOLOGY HAVE ALLOWED A METHOD TO REDUCE  INTRA 
 8. Origins of Radar: Background to the Awards of the Royal Commission, Wireless World, vol. 58,  pp. 
 PORTED OVER SWATHS OF  KILOMETERS OR MORE )N THE OCEAN APPLICATION  RELATIVELY SMALL CHANGES IN RADAR BACKSCATTER MAY COR 
 Ward, “The frequency management system of the Jindalee over-the-horizon  backscatter HF radar,” Radio Science , vol. 22, pp. 275–291, 1987. 
 Barton and H. R. Ward, Handbook of Radar Measurement , Englewood Cliffs, NJ:  Prentice-Hall, 1969. 
 Often multiple and different thresholds are used for each CPI and PRI.  Lower thresholds are allowable for higher numbers of total hits.28 It should be noted  that eclipsing and straddling, and so on, have much less effect at closer ranges where  there is usually more than enough SNR. Another serendipitous effect of this selection  technique is that as an individual PRI range clear region gets smaller, the doppler clear  region gets larger, filling-in the blind zones in both dimensions. 
 12.  There are many causes of loss and inefficiency in a radar. Not all have been included here. 
 30, pp. 258–264, 2004. 21. 
 The most commonly used ofsuch methods isthe Miller “run-down” circuit ofFig. 13.32b and c. The two circuits shown differ only inthe methods ofswitching. 
 Diffraction effects are greater at the lowerfrequencies. Thus, the radar beam of a lower frequency radar tends toilluminatemoreoftheshadowregionbehindanobstructionthanthebeamofradar of higher frequency or shorter wavelength. REFRACTION Refraction affects the range at which objects are detected. 
 But many inves - tigators process their data to provide the mean  value, and because the conversion  of a median  to a mean  requires knowledge of the probability distribution function,  care must be taken to avoid ambiguity in comparing the measurements of different  experimenters. The original analysis of the NRL 4FR data was based on median   cross sections and the assumptions of the cookie-cutter antenna beam embodied in  Eqs. 15.8 and 15.9.25–27 In later presentations of this data,28 the median  values of s  0  ch15.indd   8 12/15/07   6:16:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 RESPONSE  REGION  OF THE !-4) FILTER IN ORDER TO OBTAIN MAXIMUM CLUTTER REJECTION 4HIS CAN BE ACCOMPLISHED BY OFFSETTING THE )& OR 2& FREQUENCY OF THE RADAR SIGNAL BY AN AMOUNT EQUAL TO THE AVERAGE DOPPLER FREQUENCY OF THE CLUTTER SPECTRUM "ECAUSE THE CLUTTER CENTER FREQUENCY VARIES WITH RANGE AND AZIMUTH WHEN THE RADAR IS MOVING  IT IS NECES 
 These very important advantages were clear before themicrowave radar arthad advanced tothepoint where itwas possible toobtain nar- row beams and adequate range performance with reasonably small antenna structures. Asaresult, theBritish developed asystem operated at200 Me/see which provided elevation scanning with afixed antenna. Itwas called Variable Elevation Beam (VEB). 
 Early radar systems used antenna arrays formed by the  combination of individual radiators. Such antennas date back to the turn of the twen - tieth century.1,2,3 Antenna characteristics are determined by the geometric position of  the radiators and the amplitude and phase of their excitation. As radars progressed  to shorter wavelengths, arrays were displaced by simpler antennas such as parabolic  reflectors. 
 OUT 
 Most conventional representations of pulse shape give about the same performance, 20 dB per decade. Figure 16.28 also shows the effect of the residual on a double cancellation sys- tem. In the case of double-delay cancellation the rectangular-pulse case shows only 1.8 dB improvement over the single-delay case. 
 November. 1967. 64.Shrader, W.W.:Moving TargetIndication Radar.IEEENEREM 74Record.pl4:RadarSyslt.'ms andComponents, Oct.28-31,1974,pp.18-26.IEEECatalog no.74CHO934-0NEREM. 
 P --J;  = s ;J  
 INDEX 745 Radar, pulse,3 range performance of,8-10 word, 3 Radar beacon (see Beacon, radar) Radar components, 6-8 Radar coverage, effects ofsurface reflec- tion on, 603 Radar cross section, 21,63 Radar equation, 21-27 Radar horizon, 53 Radar in~cator, 161-175 (See do Indicator) Radar landmarks, 113 Radar navigation, 108-115 Radar performance figure, 5W Radar performance surveys, 592 Radar relay, 225, 680-735 AM vs.FM for, 717–719 antenna for, 713–719 antenna filter for, 720 frequencies ueed for, 716 100 Me/see, equipment, 721–723 300 Me/see, equipment, 719-721 uses of,680 (See af.so Relaying) Radar relay analyzer, 682 Radm relay interference, combating, 685 Radar relay receiver design, 717 Radar relay r-fequipment, 682, 713-719 Radar relay scan converter, 682 Radar relay synchronizer, 681 Radar relay system, for airborne radar, 732-735 ground-to-ground, 72&732 maximum range of,724 microwave, 723-726 simple, 681 Radar relay terminal equipment, 682 Radar relay transmitter design, 717 Radar scanning patterns (see Scanning patterns, radar) Radar system, 12 airborne, lightweight, for navigation, 611-625 c-w, 12i-159 comparison with pulse radar, 123 summary of,157-159 high-performance, for air surveillance and control, 592–61 1 testing, 590 versatility of,588Radial time baae indicator (see Indicator, radiaf time baae) Radiation Laboratory, 16 Radio Corporation ofAmerica, 24o Radomes, 314 airborne, drag of,315 electrical transmission of,316 examples of, 317–319 sandwich construction of,316 structural design of,316 RAF Fighter Command, 226 Rain echo (see Echo, from rain, 81) Ramandanoff, D.,561 Range equation, 595 Range-height indicator (RHI), 172,545- 547 Range indices, 518-524 Range markers, movable, 518 Range scopes, 165-167 Range sweep, 162 Rapid photographic projection, 221 Ratio, standing-wave (seeStanding-wav~ ratio) Rayleigh scattering, 63 Receiver, definition of,435 general-purpose, 462464 input circuits of,442 lightweight airborne, 46447o logarithmic,’ 553 MTI, adjustment oflimit level in,649 characteristics of,64&649 comparison oftypes of,648 limiting, 647, 665 lin-log, 647, 665 over-all noise figure of,32,441 radar, 433-474 typical, 46M74 ‘wideband, 470474 Receiver bandwidth, 33 Receiver design, MTI, 665 Receiving system, typical, 435-441 Rectangular waveforms, generation of, 491X501 Reflection, diffuse, 89-92 specular, 89-92 Reflection coefficient, 49 Refraction, 53 Regulator (see Voltage, Speed, etc.) Relaxation oscillator, free-running, 496 Relay radar (see Radar relay) Relaying, ofscanner data, 683. 746 RADAR SYSTEM ENGINEERING Relaying, ofsine and cosine, general methods of,701–71 1 Repeater, electromechanical, 49W-492 syncbro-driven, 490 Resistance, back, ofcrystal, 413 spreading, ofcrystal, 413 Resolution ofPPI display (see PPI dis- plays, resolution of) Resolvers, 487 Resonance charging, 382 Resonant cavities (see Cavities, resonant) Responder beacons, 246 R-f components, 391-432 R-f head, 419432 examples of,425-432 heat removal from, 421 test points in,424 &f switch, 295 R-f unit, 420 Eleke, F.F.,353 Rieke diagram, 339 Rising sun magnetron (see Magnetron, rieiig sun) Roberts, S.,662, 678 Robertson, L.M., 561 Robertson, R.M., 291, 295 Robinson, C.V.,298 Rotary joint, for coaxial line (see Line, coaxial, rotary joint for) for waveguide (see Waveguide rotary joint) Rotary spark gap, 381 R-scope, 165 Rubenstein, P.J.,64 Ryde, D., 62 Ryde, J.W., 62 s Sawtooth generators, 51&514 Scale factor, 162 Scale markers, 163 Scale-of-two, 497, 499 Scan, complex, 281 circular, 281 conical, 188, 205, 281 helical, 281 horizon, 281 Palmer, 282 sector, 199, 281 simple, 280Scan, spiral, 281 Scanner, 271 airborne, installation of,312 electrical, 291–304 oflong-range ground radar, 287 mechanical, 282-291 stabilization of(see Stabilization; Sta- bilizer) surface-based, installation of,313 weight of,283 Scanning, conical (see Conical scan) signal fluctuations due to,644646 Scanning loss, 43 scanning modulation (see Modulation, from scanning) seaming patterns, radar, 280-282 scanning rate, 116-121 azimuth, choice of,599 Schwarzschild antenna, 295-298 SCI height finder, 29~302 SCR-268, 203 SCR-270, 181 SCR-271, 181 SCR-521, 196 SCFL527, 186 SCR-540, 201 SCR-534, 207-210 close controI with, 238 scanner, 284-286 SCR-588, 186 SCR-615, 188 SCR627, 186 SCR702, 202 SCR-717, 199 SCR-720, 201 screens, cathode-ray tube (see Cathode- ray tube screens) sea return, 92-96 Second-time-around echo, 117 Sector control, 230 Sector display (see Display, sector) Sector scan (see Scan, sector) Self-synchronous system, 438 Selsyns, 487 sensitivity-time-control circuit, .460 Sequencing circuits, 710 Series gap switch, 377 &?ries peakhg (see Peaking, series) servomechanisms, 49I Shunt peaking (see Peakiag, shunt) Side lobes, 272. INDEX 747 Signal, interference of,73 minimum detectable, 2S47 minimum discernible, 34 Signal Corps Laboratories, 14 Signrd fluctuations due toscanning, &&& 646 Signal loss caused byMTI, 651 Single-tuned circuit, 445 Skiatron, 220, 483 Skin depth, 406 Slug-tuned coil, 442 SM, 188 Spark gap, rotary, 381 Specular cross section, 69 Speed control, ofmotor-alternator sets, 574 motor-, electronic, 578 ofmotor, byvoltage generator, 574 tuned-circuit, formotors, 577 Speed governor, carbon-pile, 578 Speed regulator, foraircraft motor-alter- nators, 571–578 motor-, Lee, 574 Spencer, R.C.,68 Stabilization, 304–312 airborne antenna, 30$308 frequency, ofvarious components (see varioue components) ehipborne antenna, 30%312 Stabilizer, airborne, errors in,308 line-of-sight, 30&308 roll, 306 shipborne, accuracy of,311 stable-base, 306 Stagger damping, 449 Stagger-tuned circuits, 448 Standing waves, 391 Standing-wave ratio, power, 392 voltage, 392 Storage gain (see Gain, storage) Storage tube, asdelay device, 631 Storm echo (see Echo, from storm) Straight line charging, 383 Strapped magnetron (see Magnetron, strapped) Stratton, J.A.,64 Straus, H.A.,295 Structures, radar signals from, 99 Stub support, broadband, 395 Subcarrier, phase-shifted, 695 Subcarner method, 684Superposition, optical, ofindicator scales, 218 Superrefraction, 55 Switch (see ATR, Rf, TR, etc.) pulser (see Pulser switch) Switch tubes, high-vacuum, for prdsers, 368 Synchronization, 51g524 incremental angle, method of,689–695 jittered-pulse system of,693 phase-shift method of,69$701 Synchronization methods forradar relay, comparison of,711–713 Synchronizer, radar relay, 681 Synchros, 487 Synchroscope, 164 System, back-of-the-dish, 419 radar (see Radar system) T Targets, complex, 73,7$81 compound, 73,81 extended surface, 85 Teleran, 240 Temperature, noise, ofcrystal (see Crys- tal, noise temperature of) Test equipment for MTI, special, 677– 679 Thyratron, hydrogen, 379 Time base, 162 Time-sharing method, 684 Timing markers, discrete, 52&522 TR switch, 7,407411, 420 TR tube, 407 prepulsing of,607 Tracking, automatic angle, 207-210 regenerative, ofpulses, 707 Tracking circuit, locking inof,710 Transducers, electromechanical, 667 Transformer, jog, 295 (see also type oftransformer) Transmission, c-w, ofsine and cosine, 703-711 data (see Data transmission) pulse, ofsine and cosine, 704 Transmit-receive switch (see TR switch) Tranemit-receive unit, 420 Transmitter, data (see Data transmitter) Transponders, 246 Trapping, 56-58. 
 40, pp. 1288–1300, 2002. 176. 
    -AY   $ , ,UCAS  h)ONOSPHERIC PARAMETERS USED IN PREDICTING THE PERFORMANCE OF HIGH FREQUENCY  SKYWAVE CIRCUITS v )NTERIM 2EPORT ON .2, #ONTRACT . 
 E. Uhlenbeck (eds.):" Threshold Signals," MIT Radiation Laboratory St:ries,  vol. 24, McGraw-Hill Book Company, New York, 1950. 
 The presence of ice on the reflector surface is an important consideratio,n for both the  electrical and the mechanical design of the antenna. Ice adds to the weight of the antenna and  makes it more difficult to rotate. In addition, if the ice were to close the holes of a mesh  antenna so that a solid rather than an open surface is presented to the wind, bigger motors  would be needed to operate the antenna. 
   AS WELL AS THE ADVANCED RADAR ALTIMETER  2! 
 94–98. 104. A. 
 TARGET REFERENCE IN THE FIELD OF VIEW 4HE 3TOKES PARAMETERS THAT CORRESPOND TO SUCH MEASUREMENTS ARE SUFFICIENT TO CHARAC 
 control take place in the single IF amplifier. Any variations affect all three signals simulta-  neously. After amplification, compensating delays are introduced to unscramble the time se-  quence and bring the sum signal and the two difference signals in time coincidence. 
 The next step in this reformulation of the range equation is to define a band- width correction factor CB, to allow for the possibility that the receiver filter bandwidth Bn may not be optimum. This factor is defined by the following relationship: (5/AOmuA. = tf/AOminCoA, optQ = AA., optQ (2.8) where Bn^opt is the optimum value of Bn. 
 All satellite rendezvous missions have been performed by manned vehicles. In the foreseeable future, the majority of rendezvous missions might be conducted by unmanned vehicles such as the OMV. The planned list of missions for the OMV includes (1) large-observatory servicing at the shuttle, (2) payload placement, (3) payload retrieval, (4) pay load reboost, (5) payload deboost to reentry, (6) payload viewing, (7) subsatellite mission, (8) multiple-payload mission, (9) in situ servicing mission, (10) STS transfer to space station, and (11) base support. 
 The input to the speedgate can either be the full doppler band, as in the folded or quadrature receiver, or be a subcarrier containing the full doppler intelligence. Although some clutter filtering may take place in the speedgate, earlier removal of unwanted signals is preferable. This is particularly important with the folded receiver in certain airborne situations in which the clutter has a substantial spread because mixer nonlinearities produce harmonics of the unwanted signals that may fall directly on the target signal in the speedgate. 
  AND CROSS 
 SEC. 5.6] SIMPLE DOPPLER SYSTEM 135 simplest possible indication method, apower gain ofroughly 15to1over what might behad byusing voltmeter oroscillograph can beachieved. Aural indication istherefore thelogical choice. 
 The combination of temperature, time, and manufacturing tolerances gives  rise to the need for self calibration, test, fault detection, failure diagnosis, and needed  corrections, which are performed by a subsuite of performance monitor software. Timing Structure.  The significance of the remaining parameters in Tables 5.1  and 5.2 can best be illustrated with a timing structure typical of fighter radars.7,8,9   Figure 5.14 shows a modern radar timing structure in a sequence of progressively  expanded timelines. 
 The dotted portion ofFig. 12.12 shows the beacon local oscillator attached both totheradar crystal and, through thereference cavity, toa beacon crystal. The output ofthe beacon crystal asafunction offre- quency isshown inFig. 
 The energy enters the  antenna elements, passes through the phase shifters, is renected, and again passes back  through the phase shifters to be radiated. Like the lens array, the phase shifters apply a linear  phase distribution for beam steering and a correction for the curvature of the primary wave­ front from the horn. Because the energy passes through the phase shifters twice, they need only  hair the phase-shift capability of a lens array or a conventional array; i.e., 180° of one-way  phase shift is adequate, rather than 360°. 
 CENTAGE BANDWIDTH ! BANDWIDTH FACTOR MAY  THEREFORE  BE DEFINED IN TERMS OF THE BROADSIDE BEAMWIDTH   "ANDWIDTHFACTORBANDWIDTH  BEAMWIDTH  n+     !  REASONABLE CRITERION IS TO LIMIT THE BANDWIDTH SO THAT THE BEAM NEVER SCANS BY  MORE THAN o ONE 
 FED REFLECTOR AND ITS ASSOCIATED BEAM PATTERN -ORE INFORMATION IS AVAILABLE AT ESLENGOHIO 
 and Canadian forces landed at Attu on August 15th, they found  the island abandoned. The 5,000 Japanese troops had been evacuated under cover of  fog and rain on July 28th. Later investigation determined that the Japanese evacuation  Actual altitude Refractive layer∆H FIGURE 26.3  Altitude errors ch26.indd   9 12/15/07   4:53:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Therefore, the laboratory is used almost exclusively to study in  detail how an electromagnetic wave interacts with some restricted and well-controlled  aspect of surface phenomenology that is thought to be involved in the open sea. There is a vast literature extending over almost 45 years reporting a wide variety of  laboratory experiments on microwave scattering from a disturbed water surface. The  earliest appear to be careful small-scale experiments in the mid-1960s to confirm the  existence of Bragg scatter at centimeter wavelengths,6 while at the other end of the  experimental scale, the chaos of a full-scale breaker was simulated by submerging a  hydrofoil across a 7 meter wide circulating water channel driven by 1.5 megawatts of  turbine power.121 But most laboratory experiments are more modest, involving a long  wave tank, perhaps a meter or two across, with the wave system produced by either a  controlled wind or a programmed wavemaker. 
 128]PROTECTION AGAINST EXTRANEOUS RADIATIONS 459 With the switch inthe position shown, the time constant ofthe coupling circuit is10,000 psec sothat moderately long blocks ofsignal will bepassed. With the switch reversed, the time constant is1~sec sothat individual pulses will bepassed with some differentiation; long pulses and modulation frequencies below 20kc/see will begreatly atten- uated. Even for modulation frequencies ashigh as200 kc/see, the circuit has considerable effect. 
 Mechanical construction varies widely with 1Athird method, employed onthe1500-va series PE-218 invert ersaswellasa number ofothers, istheuseofalow-voltage taponthearmature wiading.. SEC. 14.6] SPEED REGULATORS 571 different manufacturers. 
 Suppose range compression is performed, the forward and backward predicated pulses can be expressed as: sf(τ,n) =−P⎭summationtext i=1aP(i)·σ·rect⎭parenleftbigg (n−i)·tr Ta⎭parenrightbigg ·sin c⎭bracketleftbigg B⎭parenleftbigg τ−2R((n−i)tr) c⎭parenrightbigg⎭bracketrightbigg exp⎭parenleftbigg −j4πR((n−i)tr) λ⎭parenrightbigg (17) sb(τ,n−P) =−P⎭summationtext i=1aH P(i)·σ·rect⎭parenleftbigg (n−P+i)·tr Ta⎭parenrightbigg ·sin c⎭bracketleftbigg B⎭parenleftbigg τ−2R((n−P+i)tr) c⎭parenrightbigg⎭bracketrightbigg exp⎭parenleftbigg −j4πR((n−P+i)tr) λ⎭parenrightbigg (18) Since our emphasis is on how to improve the cross-range resolution. For clear expression, Equations (17) and (18) can be simpliﬁed as: sf(τ,n)=−P⎭summationdisplay i=1aP(i)s(τ,n−i) (19) sb(τ,n−p)=−P⎭summationdisplay i=1aH P(i)s(τ,n−p+i) (20) Then, the forward and backward prediction error of the echoed signal can be calculated as: ef(τ,n)=sf(τ,n)+P⎭summationdisplay i=1aP(i)s(τ,n−i) (21) eb(τ,n−p)=sb(τ,n−p)+P⎭summationdisplay i=1aH P(i)s(τ,n−p+i) (22) where sf(τ,n) and sb(τ,n–p) denote the forward and backward prediction pulse, respectively, and ef(τ,n) and e sb(τ,n–p) denote the forward and backward prediction error, respectively. a(i) represents the AR model coeﬃcient. 
 InanS-band(3000MHz)radar,forexample, theplumbing lossesmightbeasfollows: tOOftofRG-I13/V Alwaveguide transmission line(two-way) Lossduetopoorconnections (estimate) Rotary-joint loss Duplexer loss Totalplumbing loss1.0dB 0.5dB 0.4dB 1.5dB 3.4dB Beam-shape loss.Theantenna gainthatappears intheradarequation wasassumed tobea constant equaltothemaximum value.Butinrealitythetrainofpulsesreturned fromatarget withascanning radarismodulated inamplitude bytheshapeoftheantenna beam.Toproperly takeintoaccount thepulse-train modulation causedbythebeamshape,thecomputations oftheprobability ofdetection (asgiveninSees.2.5,2.6,and2.8)wouldhavetobeperformed assuming amodulated trainofpulsesratherthanconstant-amplitude pulses.Someauthorsdo indeedtakeaccount ofthebeamshapeinthismanner whencomputing theprobability of detection. Therefore, whenusingpublished computations ofprobability ofdetection itshould benotedwhether theeffectofthebeamshapehasbeenincluded. Inthistext,thisapproach is notused.Insteadabeam-shape lossisaddedtotheradarequation toaccount forthefactthat themaximum gainisemployed intheradarequation ratherthanagainthatchanges pulseto pulse.Thisisasimpler, albeitlessaccurate, method.Itisbasedoncalculating thereduction in signalpowerandthusdoesnotdependontheprobability ofdetection. 
 Section 24.4 is dedicated entirely to the analysis of the major ECM techniques  and strategies. It is important to understand the ECM threat to a radar system in order  to be able to efficiently react to it. To facilitate the description of the crowded family  of ECCM techniques (Sections 24.6 through 24.10), a classification is attempted in  Section 24.5. 
   PP n   *UNE   - ! &RUCHAFT AND , - 3ILBER  h5SE OF -ICROWAVE FERRITE TOROIDS TO ELIMINATE EXTERNAL MAGNETS  AND REDUCE SWITCHING POWER v 0ROC )2%  VOL   P   !UGUST   * &RANK  # ! 3HIPLEY  AND * ( +UCK  h,ATCHING FERRITE PHASE SHIFTER FOR PHASED ARRAYS v  -ICROWAVE *  PP n  -ARCH   7 * )NCE AND $ ( 4EMME  h0HASE SHIFTERS AND TIME DELAY ELEMENTS v IN  !DVANCES IN -ICROWAVES   VOL   .EW 9ORK !CADEMIC 0RESS  . 
 J. R., Jr.: " Radonie Iirlgirieeririg tiandbook," Marcel Dekker, Inc., New York, 1970.  125. 
 21-23, 1975, pp. 221-225.  83. 
 Ostro, S.J.; Hudson, R.S.; Benner, L.A.M.; Giorgini, J.D.; Magri, C.; Margot, J.-L.; Nolan, M.C. Asteroid Radar Astronomy ; 2002; pp. 151–168. 
 TRACKING PRECISION 4HIS CHAPTER IS DEVOTED TO TRACKING RADAR  BUT MONOPULSE TECHNIQUES ARE USED IN  OTHER SYSTEMS INCLUDING HOMING DEVICES  DIRECTION FINDERS  AND SOME SEARCH RADARS (OWEVER  MOST OF THE BASIC PRINCIPLES AND LIMITATIONS OF MONOPULSE APPLY FOR ALL APPLI 
 System architectures and algorithms for radar imaging by MIMO-SAR. In Proceedings of the IEEE Radar Conference, Pasadena, CA, USA, 4–8 May 2009; pp. 1–6. 
 Iftwo coils are used, they are usually placed together (on the same yoke when iron isused), but in extreme cases they must beseparated toavoid interaction. Arotating coil and afixed coil can beused incombination—for example, toproduce anoff-center PPI. The fixed coil isplaced outside ofthe rotating one, which must then contain noiron. 
 RANGE WEATHER SUR 
 This information is then input to a pulse-sort pro- cessor which deinterleaves the pulses into the pulse repetition interval (PRI) appropriate to each emitter. Further comparison against a store of known ra- dar types permits the generation of an emitter list classified with its tactical . value. 
 12.3). Inthis particular form ofPPI, these sweep “components” are formed bypassing asawtooth waveform through asine-cosine “resolver” onthe scanner. The resolver isavariocoupler orasine- cosine potentiometer which, when excited byagiven waveform, produces two “components” ofthe same waveform whose amplitudes arepropor- tional respectively tothe sine and the cosine ofthe orientation angle of theresolver. 
 A  portioti of tlie video-atnplifier output is passed tlirough a low-pass or smoothing filter and fed  back to control the gain of the IF amplifier. The larger the video output, the larger will be tlie -  . -  Conical scan modulation  to angle-error detector  amplifier amplifier gate and boxcar 4 cal-scan rnodulation; (h) same pulse  I/$ train after passing Ihrough boxcar  (b) generator. 
 FREQUENCY REFERENCES TO . È°ÓÓ  2!$!2 (!.$"//+  ENSURE COHERENCE OF ALL OSCILLATORS WITHIN THE RECEIVER 
 , &U AND ! #AZANAVE EDS    3ATELLITE !LTIMETRY AND THE %ARTH 3CIENCES   3AN $IEGO  !CADEMIC 0RESS    * 2 *ENSEN AND 2 + 2ANEY  h$ELAY $OPPLER RADAR ALTIMETER "ETTER MEASUREMENT PRECISION v  IN 0ROCEEDINGS )%%% 'EOSCIENCE AND 2EMOTE 3ENSING 3YMPOSIUM )'!233g  3EATTLE  7!   )%%%    PP n  2 + -OORE AND # 3 7ILLIAMS  *R  h2ADAR RETURN AT NEAR 
 BASED OBSERVATIONS OF CLOUDS AND PRECIPITATION v "ULL !M -ETEOROL 3OC  VOL   PP n    % % 'OSSARD AND 2 ' 3TRAUCH   2ADAR /BSERVATIONS OF #LEAR !IR AND #LOUDS   !MSTERDAM  %LSEVIER    3 +ATO 4 4SUDA  - 9AMAMATO  4 3ATO  AND 3 &UKAO  h&IRST RESULTS OBTAINED WITH A MIDDLE AND  UPPER ATMOSPHERE -5  RADAR v * !TMOS 4ERR 0HYS   VOL   PP n  .   -%4%/2/,/')#!, 2!$!2   £°{  3 ' "ENJAMIN  " % 3CHWARTZ  % * 3ZOKE  AND 3 % +OCH  h4HE VALUE OF WIND PROFILER DATA IN  53 WEATHER FORECASTING v "ULL !MER -ETEOR 3OC  VOL   PP n    2 % #ARBONE  2 3TRAUCH  AND ' - (EYMSFIELD  h3IMULATION OF WIND PROFILERS IN DISTRIBUTED  CONDITIONS v IN RD #ONF 2ADAR -ETEOROL  VOL )  !-3  "OSTON    PP n  2 ' 3TRAUCH  " , 7EBER  ! 3 &RISCH  # ' ,ITTLE  $ ! -ERRITT  + 0 -ORAN  AND $ # 7ELSH   h4HE PRECISION AND RELATIVE ACCURACY OF PROFILER WIND MEASUREMENTS v  * !TMOS /CEAN 4ECHNOL   VOL   PP n    0ROCEEDINGS OF )NTERNATIONAL 3YMPOSIA ON 4ROPOSPHERIC 0ROFILING  nPRESENT  2 * $OVIAK  2 * ,ATAITIS  AND # , (OLLOWAY  h#ROSS CORRELATIONS AND CROSS SPECTRA FOR SPACED  ANTENNA WIND PROFILERS v 2ADIO 3CI  VOL   PP n    * 3 6AN "AELEN AND ! $ 2ICHMOND   h2ADAR INTERFEROMETRY TECHNIQUE 4HREE 
 RANGE  $ SHIPBOARD SEARCH RADAR SYSTEM  FOR WHICH A NEW SOLID 
   "ELL 4ELEPHONE ,ABORATORIES  7HIPPANY  .*    $ 3 :RNIC `  h%STIMATING OF SPECTRAL MOMENTS FOR WEATHER ECHOES v  )%%% 4RANS 'EOSC %LECTRON    VOL '% 
 The  removal of snow by thermal means (heaters) is generally quite expensive; In some of the  smaller rigid radomes, snow can be removed mechanically by tying a rope at the top and  having someone walk the rope around the radome to knock ofT the snow.  Liquid water can collect on a radome due to condensation or rainfall. In some cases, the  impingement of rain on a radome can have a more serious effect on the system performance  than the rainfall along the propagation path. 
 AXIS ANGLE 
 (Alter Cutler et uI.,~ Proc. IRE.) 11 111111~111111~ 1  Moin lobe  - i" \/ Vestigial lobe or shoulder f -  st side lobe  Spillover radiation  (7.1)224INTRODUCTION TORADAR SYSTEMS Directive gain.Ameasure oftheahilityofanantellna tocollccntratecncrgy inaparticular direction iscalledthegain.Twodifferent, butrelateddefinitions ofantenna gainarethe directive gainandthepowergain.Theformerissometimes calledthedirectivity, whilethelatter isoftensimplycalledthegain.Bothdefinitions areofinteresttotheradarsystems engineer. Thedirective gainisdescriptive oftheantenna pattern, butthepowergainismoreappropriate foruseintheradarequation. 
 [ CrossRef ] 20. Tang, S.; Zhang, L.; Guo, P .; Zhao, Y. An Omega-K Algorithm for Highly Squinted Missile-Borne SAR with Constant Acceleration. 
 Phys., January, 1954.  26. Woodward, P. 
 CALLED SENSITIVITY VELOCITY CONTROL 36#  ALGORITHM  4HE 36# #ONCEPT   3ENSITIVITY VELOCITY CONTROL 36#  IS USED WHEN A RADAR MUST  DETECT AIRCRAFT AND MISSILE TARGETS IN THE PRESENCE OF RETURNS FROM UNWANTED TARGETS SUCH AS LARGE BIRDS OR BIRD FLOCKS 4HE CRITERIA TO ACCEPT OR REJECT TARGETS IS BASED ON A COMBINATION OF THE RADIAL VELOCITY AND APPARENT 2#3 RADAR CROSS SECTION  OF THE TARGET RETURNS 4HE DESIRED TARGETS MAY HAVE AN 2#3 SMALLER THAN A SINGLE BIRD  OR POSSIBLY  &)'52%  6ELOCITY RESPONSE OF CLUTTER MAP . Ó°nn  2!$!2 (!.$"//+  A BIRD FLOCK IN A SINGLE RADAR RESOLUTION CELL  4HUS  DISCRIMINATION REQUIRES A PARAME 
 The subsequent process ofbeacon reply isdescribed byasimilar equation with the subscripts band rinterchanged throughout. Ifthe same antenna orsimilar antennas are employed for transmission and reception atthebeacon and likewise attheradar, asisnearly always the case, thequantity intheparenthesis hasthesame value forinterrogation andreply, and wecan infer thecorollary relation s P,,b E–P,(15) Inpractice, the gain G,ofthebeacon antenna isfixed atarelatively lownumber bytherequirement ofsomething like omnidirectional cover- age. The remaining factor intheparenthesis inEq. 
 G. C.: "Frequency Modulated Radar," McGraw-Hill Book Company, New York, 1949.  30. 
 CHANNEL SIDELOBE BLANKER   
 177.  3. Vari Vleck. 
 LIMITED TARGET DETECTION u #OHERENT INTEGRATION TIMES MAY EXTEND TO HUNDREDS OF SECONDS  AS (&372 IS NOT RELIANT ON THE IONOSPHERE AS A MEDIUM FOR PROPAGATION u /NLY VERTICALLY POLARIZED ELECTROMAGNETIC WAVES PROPAGATE EFFECTIVELY IN THE SURFACE WAVE MODE OVER THE SEA  SO THE (&372 SIGNAL 
 In actual processing, in order to avoid possible ambiguity of interferometric phase difference, the following judgements on the interferometric phase difference are required: /braceleftBigg ifΔϕ>π,Δϕ−2π ifΔϕ<−π,Δϕ+2π. (31) 162. Sensors 2018 ,18, 3750 4. 
 Some methods for dynamic scene such as video signal processing and dynamic MRI imaging can be introduced to WASAR imaging. LS-CS-Residual [ 17] has been proposed for dynamic CS problems, such as dynamic magnetic resonance imaging (MRI). The idea of LS-CS-Residual is to perform CS not from the observations,but from the least squares residual computed using the previous support estimation. 
 The ambiguities may be resolved by additional  antennas spaced closer together. The spacing between the individual antennas in the interfer-  ometer systeni corresponds to the separation between frequencies in the multiple-frequency  distance-~iieasuri~ig technique. The minitrack system is an example of an interferometer in  which angular ambiguities are resolved in a manner sfmilar to that described.64  The multiple-frequency CW radar technique has been applied to the accurate measure-  ment of distance in surveying and in missile guidance. 
 Aconical-scan-on-receive-only (COSRO) tracking radar rad~atesanonscanning transmit beam,butreceives withaconicalscanning beamtoextracttheangleerror.Theanalogous operation withsequential lobingiscalledlobe-on-receive-only (LORO).. 5.4 MONOPULSE TRACKING RADAR1~2~'3-'8  The conical-scan and sequential-lobing tracking radars require a mininll~nl number of p~~lws  in order to extract the angle-error signal. In the time interval during which a measurement is  made with eiiher sequential lobing or conical scan, the train of echo pulses must contain no  amplitude-modulation components other than the modulation produced by scanning. 
 SEARCH DETECTION RANGES !LL DECISION AIDS ARE DISPLAYED AS FUNCTIONS OF RANGE  AZIMUTH ANGLE  ANDOR HEIGHT $ETECTION PROBABILITY  %3- VULNERABILITY  AND COMMUNI 
 Aminimum ofthreenoncoplanar beamsareneededto determine thevectorvelocity, tllatis,thespeedanddirection oftravel. Doppler-navigation radarmeasures thevectorvelocity relativetotheframeofreference oftheantenna assembly. Toconvert thisvectorvelocity toahorizontal reference onthe grounu, thcdirection oftheverticalmusthedetermincd bysomeauxiliary means.Theheading oftheaircraft. 
 OF 
 FINGERED &%4 STRUCTURE DRAIN 
 (ILL   RD %D  .EW 9ORK -C'RAW 
 DOWN 4HE RANGE IS FOUND BY SELECTING RETURNS FROM EACH OF THE THREE SEGMENTS THAT SATISFY THE RELATIONS   FFF         FF F      . 
 TRACKING CAPABILITY 4HEREFORE  IT IS IMPORTANT TO KNOW HOW MUCH ERROR CAN BE TOLERATED  WHICH SOURCES OF ERROR AFFECT THE APPLICATION  AND WHAT IS THE MOST COST 
 21.2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 which takes the form of a cross section of the ground surveyed by the GPR, is shown  in Figure 21.2. The horizontal scale is 10 cm per marker and the vertical scale is time  in nanoseconds (51 ns). An explanation of the image is provided later in this chapter. 
 BEAM CLUTTER TO ZERO  DOPPLER  AS SHOWN IN &IGURE B &)'52%  ,OCI OF CONSTANT NORMALIZED RADIAL VELOCITY  6R6G AS A FUNC 
 Scattering also  occurs from the environment—clutter—so models of the scattering coefficient per  unit area of land and ocean surfaces, or per unit volume of the turbulent ionosphere,  are used to provide effective RCS values for Eq. 20.2 when those natural scatter - ers are the “targets” of interest. Thus, for the RCS of Earth clutter, the normalized  surface scattering coefficient s ° is multiplied by the resolution cell size A. 
 TIONS   4HE PRIMARY ENABLER FOR MULTIFUNCTIONAL RADAR IS SOFTWARE 
 The ratio detector sums signal- to-noise ratios and is specified by  x j mx j k x j ki i i km in 2 2 2 111 21 1( ) ( ) ( ) + + + − −  ==∑∑ ∑  (7.12) where xi(j) is the ith envelope-detected pulse in the jth range cell and 2 m is the number  of reference cells. The denominator is the maximum-likelihood estimate of σi2, the  noise power per pulse. The ratio detector will detect targets even though only a few  returned pulses have a high signal-to-noise ratio. 
 &REQUENCY 2ADAR .EEDS2ESOURCES   /FFICE OF THE 5NDER 3ECRETARY OF $EFENSE FOR !CQUISITION AND 4ECHNOLOGY  7ASHINGTON  $#   !PRIL   - ) 3KOLNIK   )NTRODUCTION TO 2ADAR 3YSTEMS   RD %D .EW 9ORK -C'RAW 
 xviii     Contents   11. Radar Cross Section   ............................................... 11.1  11.1 Introducti on  ............................................................. 
 Limiting or logarithmic receivers must define an allowable error in their outputs. Gain-controlled receivers must distinguish between instan- taneous dynamic range and that achieved partly as a result of programmed gain variation. 3. 
 ·  31. Vadus. J. 
 ITY OF DETECTION FOR EACH LOOK  0D LOOK  IS USED TO COMPUTE THE PROBABILITY OF DETECTION  FOR A DWELL  0D DWELL  7HEN A DWELL REQUIRES  M DETECTIONS OUT OF  N LOOKS FOR A TARGET  DECLARATION  THE 0D DWELL IS   0K N00D KMN DK DN      DWELL LOOK LOOK  ¤ ¦¥³ µ´ 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 22.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 Touchscreen technology is sometimes employed. 
 WAY HALF 
 Dashed lines show the  flow of power. During reception (Fig. 9.7b) the ATR tubes present a high impedance which  results in the echo-signal power being reflected to the receiver. 
 The tube trans- mitter generates 3 MW of RF power at the peak of a 10-jxs pulse and an average RF power of 8 kW. The radar is instrumented to 256 nmi and up to 30° in eleva- tion and 100 kft in height. The antenna rotates at 6 r/min. 
 CIRCLE DESIGN TEAM 4HE ! 
   
 IEEE , vol. 12,   pp. 1873–1890, 1994. 
 OND TRANSISTOR OPERATES OVER THE NEGATIVE INPUT SIGNAL SWING (IGHER EFFICIENCY BUT  HIGHER DISTORTION IS EXPERIENCED WHEN COMPARED WITH A #LASS 
 A wideband input transducer and  a frequency-selective (dispersive) output transducer are used in Figure 8.7 a. When an  impulse is applied to the input, the output signal is initially a low frequency that increases  (based on the output transducer finger spacings) at later portions of the pulse. This results  FIGURE   8. 
 260--27 l, March, 1973.  148. Brennan, L. 
 The STC law, and the way it varies by use of the manual  control, can be complex. It is attempting to reduce the dynamic range of the received  waveform and to provide, in association with the gain settings, optimized thresholds.  ch22.indd   5 12/17/07   3:02:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Beyond  the horizon, the surface wave is the dominant contributor, but at shorter ranges, all  three mechanisms must be taken into account. Accordingly, the relationship between  (i) target echo strength and (ii) the range and altitude of the target is not a simple  one. Moreover, the calculation of the field distribution is computationally expensive if  ch20.indd   71 12/20/07   1:17:13 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7Maneuver Model Q-submatrixSteady-state Gain Relation and  Tracking Index Tuning Method Characteristics Model no. 1: White noise  (spectral density q g2/Hz)  acceleration sampled by radar  measurement45.qT T T Tk k k k3 2 23 /β= 6 3 3 36 362− − − +α ααand γσtrack=qT m3 2Vary q to increase/   decrease gains  and obtain desired  performance using  equations in Table 7.3.Accommodates variable  measurement rates well. 
 The  analysis of these reflector edge diffraction effects and associated F/B ratios for some  common reflector geometries are described by Knop.3 Feed Blockage.4,5 Many reflector systems suffer feed and/or feed-support  blockage to some degree. For center-fed geometries, there will definitely be block - age because the feed is within the FOV of the reflector. A consequence of blockage  is higher sidelobes, the levels of which depend upon the blockage area. 
 Bates, C. N.: New Advances in Doppler Radar, Countermeasures, vol. 2, pp. 
 The MTI must be capable of coping with moving, rather than  statioiiary. clutter. Iii this regard the MTI design is more like that for detecting targets in  wcatllcr clutter. 
 .OISE 2ADAR #ALCULATION 3OFTWARE AND 5SERS -ANUAL   .ORWOOD  -! !RTECH (OUSE  )NC     PP n  $ # 3CHLEHER   -4) AND $OPPLER 2ADAR  .ORWOOD  -! !RTECH (OUSE  )NC    PP n  & * (ARRIS  h/N THE USE OF WINDOWS FOR HARMONIC ANALYSIS WITH THE DISCRETE &OURIER TRANSFORM v  IN 0ROCEEDINGS OF THE )%%%  VOL   NO   *ANUARY   PP n  7 ! 3KILLMAN   2ADAR #ALCULATIONS 5SING THE 4) 
 M 
 Itisoften useful toinclude separate adjustments forthe saturation levels ofthesignals, sothat stronger beacon signals will stand out when superimposed onsaturated ground ‘(clutter” from the radar. Also, ifthe pulses ofthe beacon areshort, itispossible toimprove the display bystretching them inthevideo amplifier ofthereceiver. Some beacons aremade toreply only tointerrogating pulses ofproper length, ortothose having other special characteristics, asdiscussed below. 
 1994 ,32, 823–836. [ CrossRef ] 25. Li, F.; Han, B.; Lin, X.; Hu, D.; Ding, C. 
 Therefore the following formula  arises for the slant range:     0 2delaytcR     If the respective running time tdelay is known, then the distance R between a target and the radar set  can be calculated by using this equation.   Maximum Unambiguous Range   A problem with pulsed radars and range measurement is how to unambiguously determine the  range to the target if the target returns a strong echo. This pro blem arises because of the fact that  pulsed radars typically transmit a sequence of pulses. 
 3.2. Phase Compensation Based on Fast Minimum Entropy Method The features of ship, image entropy and image contrast (IC) are regarded as the evaluation criteria of image focusing. If the image is well-focused, the entropy and IC attain their minimum and maximum values, respectively [ 25]. 
 J:/cctI'lJllics. vol..14,no.46,pp.114,JIS,117.Nov.17,1961. 107.(ient,II.:TheBootlace Aerial.URLJ.(RoyalRadarEstablishment, Malvern. 
 A. Weil, “Applying the Amplitron and Stabilotron to MTI radar systems,” in IRE Nat. Conv. 
 The synthesis procedure in focusing the acquired data is carried out by coherent integration. Each target on the ground contributes to the radar return on several subsequent transmitted pulses. In SAR two main directions are important to focus the data: slant range direction, in which transmitted pulses travel, and azimuth direction, i.e., the direction of sensor movement. 
 GET DETECTION IN SUCH SETS OF FULLY 
 NAL ON LINE  4HE LATTER SIGNAL IS SPECTRALLY MULTIPLIED BY THE FILTER RESPONSE SHOWN ON LINE  TO REMOVE THE COPIES OF THE NEGATIVE 
 GROUND  INTERFACE IS  CM DIFFERENT FROM THE EARLIER MODEL  4HE MODELED TARGET IS A CYLINDER WITH A RADIUS OF  CM AND A HEIGHT OF  CM )T IS SHALLOWLY BURIED AT ABOUT  CM BELOW THE AIR 
 x is the fraction of the  antenna aperture that the antenna is displaced per interpulse period (x = 0 corresponds to no platform  motion.) (From Andrew~.~~)  MTIANDPULSE DOPPLER RADAR143 Basedonananalysis ofantenna radiation patterns andexperimental data, Staudaher~8 gives thestandard deviation oftheclutterspectrum duetoplatform motionas v"apm::::0.6-a(4.37) (4.38)where l'"isthehorizontal component ofthevelocity perpendicular totheantenna pointing­ direction andaistheeffective horizontal aperture width.Theantenna beamwidth isassumed tobeapproximated by08=A./a.[Equation (4.37)isnotinconsistent withthesimplederivation ofEq.(4.36).]Ifthemeandoppler-frequency shiftoftheclutterechoisperfectly com­ pensated, thelimitations ontheimprovement factorduetoclutterspreadcanbefoundby assuming agaussian spectral shapeandsubstituting thestandard deviation ofEq.(4.37)into theexpression ofEq.(4.27)toobtain 2N1(1a)2NI Ipm=N;!1.2n~"Tp (4.39)whereN,isthenumberofdelaylinesilltheMTIprocessor. Iftheclutterspreadarmduetothe platform motioncombines withtheclutterspreadacduetointernal cluttermotionsuchthat lhetotalstandard deviation al'oftheclutterspectrum isaf=a;+a:m,theMTIimprove­ mentfactorforthetotalclutterspectrum is 2N, [J;12N1 /cs=N,!2rc(a;: <1:m)I/2 ThesolidcurvesofFig.4.35plotthisequation forathree-pulse delay-line canceller(N,=2). Ifthewidening orthespectrum isaresultoftheradarplatform's velocity, itseffectscanbe mitigated bymakingtheradarantenna appearstationary. 
 Background and descriptions of the common three-terminal device types and their  associated technologies as utilized for the common radar bands are described in the  following sections. Silicon Bipolar Junction Transistor . The silicon bipolar junction transistor  (BJT) was the earliest of the microwave power devices and found its way into tube  replacement transmitters and phased array applications starting in the late 1970s. 
 Mar.. 1959.  82. 
 1714] MICROWAVE SYSTEM FORPOINT-TO-POINT SERVICE 723 Two miniature double diodes are included inthe transmitter for monitoring purposes. One ofthese tubes isconnected asadiscriminator toprovide avideo-output test point attheantenna-line connector. Dur- ing alltesting, this video signal gives anaccurate over-all check ofthe r-fand video sections ofthe transmitter. 
 MATIONS SUCH AS A "UTLER MATRIX 4HE GENERAL GOAL IS TO REDUCE THE SPATIAL DEGREES OF FREEDOM  WHILE STILL PROVIDING ACCESS TO ARRAY RESPONSES THAT ALLOW FOR ADEQUATE CLUTTER CANCELLATION AND BEAMS THAT CAN BE USED TO CANCEL DIRECTIONAL INTERFERENCE AS WELL 4HE RESULTING BEAM RESPONSES MUST SPAN THE CLUTTER AND JAMMING INTERFERENCE SPATIALLY IN ORDER FOR THIS TYPE OF TRANSFORMATION TO BE EFFECTIVE &OR EXAMPLE  IF A RADARS CLUT 
 diameter atthis magnification. Plotting means employing this device were just being worked out at the end ofthe war. ~Itappeared that this was ahighly effective and satisfactory method oflarge-scale direct presentation ofaradar display. 
 93. Cooke, C.R.: Laser Radar Systems, Some Examples. Proc. 
 , 
 Atwo-stage limiter isused to insure constant input-signal voltage atthe discriminator. Both limiter tubes operate atreduced plate and screen voltages toreduce the grid swing necessary tocause plate limiting. Afast time constant inthegrid circuit ofthe first limiter was chosen todiscriminate against impulse noise byproducing theYlmiting bias quickly. 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .476x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 1. Detection-to-track fusion (see Figure 7.39, upper half) associates each detection to  the networked track, calculated potentially using detections from all radars. 
 ' 2ANGING  AS SHOWN PREVIOUSLY IN &IGURE   AND LATER IN &IGURES  AND  )T CONSISTS OF A FREQUENCY CHANGE SETTLING TIME PASSIVE RECEIVIN G TO BE SURE THE BAND ISNT  JAMMED CALIBRATE THAT DOESNT INTENTIONALLY RADIATE BUT OFTEN THERE IS SOME 2& LEAKAGE RADIATED AN AUTOMATIC GAIN CONTROL !'#  INTERVAL IN WHICH A NUMBER OF PULSES ARE TRANSMITTED TO SET THE RECEIVER GAIN AND FINALLY TWO INTERVALS IN WHICH RANGE  DOPPLER  AND ANGLE DISCRIMINANTS ARE FORMED 4HESE #0)S OFTEN BUT NOT ALWAYS HAVE CONSTANT POWER  FREQUENCY SEQUENCE  02& SEQUENCE  PULSEWIDTH  PULSE COMPRESSION  AND BANDWIDTH    x°ÎÊ Ê " 
 Ifthk isdone, thenew tube atwavelength ~will operate attheoriginal voltage and current, and atamagnetic field H=~Ho,where Hoisthe operating magnetic field ofthe original magnetron. The power input, and thus the power output, increases with increasing wavelength. A rough rule is:Thepulse power output (orinput) ofsculedmagnetrons variesasthesquareoftheirwavelength. 
 Delano38 gives data from two aircraft in formation that are  gaussian-distributed when completely unresolved, but change shape at close range  where the antenna begins to resolve the two aircraft (as described in Section 9.1 1).TWO SMALL AIRCRAFTAIRCRAFT CONFIGURA TION BOMBER (LIKE B52) SMALL TWO- ENGINE AIRCRAFT FIGHTER0.2 L0.5 L 0.29 L 0.25 L 0.14 L0.35 L 0.20 L 0.18 L 0.10 LGEOMETRICAL APPR OXIMA TIONRADIUS OF GYRA TION (R)ANGLE SCINTILLA TION (RMS) s = R/ 2 L L FIGURE   9.21  RMS angle scintillation based on the theoretical relation to the radius-of-gyration of the  distribution of reflecting areas of the target FIGURE   9.22  Amplitude probability distribution of angle scintillation measured on a small  two-engine aircraft ch09.indd   32 12/15/07   6:07:35 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 
 It is still considered a slower device than other semiconduc - tors, such as GaAs, because the mobility in silicon MOSFET channels is relatively low.  Although the bulk mobility of silicon is lower than GaAs, it does not preclude the sili - con LDMOS FET as a high frequency power transistor. The continuous process fabrica - tion improvement in the silicon CMOS industry has resulted in sub-micron production  transistor feature sizes, and the smaller feature sizes allow for a compensated increase  in higher frequency operation; that is, it can exhibit usable gain into S band. 
 AES-6, pp. 51-61, January 1970. Reprinted in Barton, D. 
 F. Lane, Jr.: The AN/APN-22 Radio Altimeter, IRE Tratu., vol. ANE-I. 
 Since in practice the process typically  includes some form of limiting, the output amplitude A t( ) generally has a lower ampli - tude variation than the input signal amplitude A(t). Because the multiplication process multiplies up the variations in the signal phase  by factor M, input phase noise and spurious phase modulations are increased by  20 log10(M) dB. Similarly, variations in the phase of the signal as a function of fre - quency are multiplied up. 
 Wahl, P. H. Eichel, D. 
 MODULATED RADAR ALTIMETER  WHICH  RETURNED  READINGS DURING ITS DESCENT FROM ORBIT TO ITS DEMISE ON THE SURFACE OF 6ENUS   &)'52%   4HE #RYO3AT SATELLITE AND ITS 3)2!, ALTIMETER 4HE  TWO ANTENNAS )NTERFEROMETRIC MODE  ARE ATHWART THE VELOCITY VECTOR   SO THAT THE DIFFERENTIAL PHASE MODULO  O    OF THE FIRST RETURN INDICATES  THE CROSS 
 737–745, 1985. 45. R. 
 Ifthis isundesirable one ofthem can beremoved byamethod involving theuse ofamultiphase rotor inthesecond synchro. Asecond modulation envelope, 90°out of phase with the first, isobtained and used toblank one ofthe markers (see Fig. 4.5, Vol. 
 The plate potential isdetermined bythesetting ofthe delay potentiometer. Ifa sufficiently strong negative trigger issupplied through Vztothefirst grid, the fall inthe cathode potential turns onthesecond control grid. The establishment ofplate current further reduces the potential ofthe first control grid sothat thesecond grid isturned full on. 
 9.2  9.3 Electronic Warfare Support Measures  ....................  9.2 9.4 Electronic Countermeasures  ..................................  9.4  9.5 Objectives and Taxonomy of ECCM  Techniques  ............................................................. 
 AMBIGUOUS POINT TARGETS TEND TO BE DEFOCUSED 4HE PRINCIPAL MEANS OF SUPPRESSING AMBIGUITIES IS TO CONFINE THE MAIN BEAM OF  THE ANTENNA SO THAT THE POTENTIAL SOURCES OF AZIMUTH OR RANGE AMBIGUITIES ARE NOT ILLU 
 MEDIUM 
 PATTERN  PEAKS TO BE NEAR THE NULLS OF THE SUM PATTERN TO MATCH 'RISSETTI ET AL HAVE SHOWN THAT FOR STEP 
 Landry: A High-Power Coaxial Ferrite Phase Shifter, IRE  Trans, vol. MTT-9, p. 577, November, 1961. 
 The  doppler tracking filter is sometimes called a speed gate.  5.9 COMPARISON OF TRACKERS1  Of the four continuous-tracking-radar techniques that have been discussed (sequential lobing,  conical scan, amplitude-comparison monopulse, and phase-comparison monopulse), con~cal  scan and amplitude-comparison monopulse have seen more application than the other two.  The phase-comparison monopulse has not been too popular because of the relative awkward-  ness of its antenna (four separate antennas mounted to point their individual beams in the same  direction), and because the sidelobe leveliiinight be higher than desired. 
 62. H. Davies, “The reflection of electromagnetic waves from a rough surface,” Proc. 
 MINATES THE GROUND )N PULSE RADARS  ONLY THAT PART OF THE GROUND AREA PROVIDING SIGNALS BACK TO THE RADAR AT A PARTICULAR TIME CAN BE CON 
 Typical VHS airborne SAR geometry. Figure 6a,b shows the spatial variance of the Doppler rate and the derivative of the Doppler rate, respectively. The center of the ﬁgure represents the beam irradiation position B2. 
 2518–2535, October 1992. 129. Special Issue on Superresolution, The Lincoln Laboratory Journal , vol. 
 This bending of rays is known  as refraction . Depending on surface curvature and body material, reflected and transmitted  rays may diverge from one another or they may converge toward each other. This  dependence is the basis for the design of lenses and reflectors at radar wavelengths  as well as at optical wavelengths. 
 ,  w  [l/ l, f l:f l.J  w er 0 ~='Ir  Frequency 2~· 3ip  Figure 4.20 Freq!Jency-response characteristic of an MTI using range gates and filters. MTI ANO PULSE DOPPLER RADAR 119  MTl radar using range gates and filters is usually more complex than an MTI with a  single-delay-line canceler. The additional complexity is justified in those applications where  good MTI performance and the nexibility of the range gates and filter MTI are desired. 
 Romeiser, A. Schmidt, and W. Alpers, “A three-scale composite surface model for the ocean  wave-radar modulation transfer function,” J. 
 Knittel (eds.), Artech House, Inc., Dedham; Mass., 1972, pp. 212-218.  25. 
 Thus some  means should be included to inform the operator when the detection probability has been  lowered because of the CFAR action.  It is better to incorporate in the design of a radar means for eliminating unwanted signals  before they enter the ADT than to depend on CFAR to eliminate them. Examples of signal  processing techniques that eliminate unwanted signals without a severe penalty in detectability  include MTJ for clutter echoes, the low sidelobe antenna and/or sidelobe cancelers for jam­ ming noise, and the sidelobe blanker or the prf filter for pulse interference. 
 VIEWING RADAR SUCH AS A SCATTEROMETER WILL GENERATE VIRTUALLY NO BACK 
 SION FUNCTION WITH THE REMAINDER PERFORMED IN POLAR FORMAT PROC ESSING 4HE DECHIRPED  AND PARTIALLY FILTERED OR COMPRESSED OUTPUT  SHOWN AT POINT # IN &IGURE   MAY BE RESAMPLED AGAIN AT A NEW  F 3  AS INDICATED IN THE RIGHT GRAPH SHOWN IN &IGURE   POINT  # )N ANY CASE  AZIMUTH VARIABLE PHASE ADJUSTMENT AND BIN MAPPING WHICH COMPEN 
 46.Stuetzer, O.M.:Development ofArtificial Microwave OpticsinCiermany, Proc.IRE,vol.3H, pp.1053-1056, September, 1950. 47.Harvey, A.F.:Optical Techniques atMicrowave Frequencies, Prot.lEE,vol.106,pt.H, pp.141--157, March,1959.Contains anextensive bibliography. 48.Kelleher, K.S.,andC.Goatley: Dielectric LensforMicrowaves, Electronics, vol.28,pp.142-145, August, 1955. 
 PER 
 10.3 Basic Princi ple of SAR   "Synthetic Aperture Radar" [24], henceforth referred to as SAR, operates from a moving ca r- rier, which moves along or over the target area.  An example “fly -by” is illustrated in Figure  9.3.    Figure 10.3  Three -dimensional representation of SAR g eometry. 
 RESOLUTION  THUMBTACK 
 The LO must be reasonably quiet, and the phase delay of the amplifiers must be matched. Figure 14.6 gives the servo-loop gain, and Fig. 14.7 shows the three resulting curves: A, the FM noise on the free-running oscillator; B9 the FM noise of the stabilized oscillator; and C, the expected theoretical improvement based on the servo gain and the noise analysis. 
 Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 95        Figure 11.5  Wideband polarimetric RCS measurement station with a quasi -monostatic  antenna system.   11.4.3  Calibration and Error Correction for Polarime tric RCS  Measurements   In Figure 11.6 a typical polarimetric measurement system is schematically shown for RCS and  antenna measuring technology.  The measurement system is complete in block 1 of Figure  11.6. 
 Thereceiver isalways ofthesuperheterodyne type and consists ofthe signal channel and the local oscillator, together with frequency-control circuits forthe latter. Strictly speaking, this should include allequip- ment concerned with thereceived signal, beginning with theantenna and ending with the input terminals ofthe indicator proper. However, in practically allradar applications the antenna, the TFi tube, and the r-f line connecting them areshared with thetransmission channel, and the techniques inthese sections aredictated somewhat more bythe trans- mitter requirements than bythose ofthereceiver. 
 244 RADAR BEACONS [SEC. 8 duration and frequency oftheradar pulse, and isnotappreciably delayed, the beacon acts somewhat like anecho amplifier. The intensities of received and transmitted signals are, tobesure, independent, rather than infixed proportion asinthecase ofatrue amplifier. 
 Wilson and Schreiber149 illustrate how meteorologi - cal doppler radar can be used to detect locations where new thunderstorm develop - ment is likely to occur. Many weather radars have sufficient sensitivity to detect  discontinuities of clear air echoes in the lower 2 to 4 km of the atmosphere out to  50 or 100 km. This detection occurs principally in the summer months when the  backscattering mechanism is caused by insects in the lower levels of the atmospheric  boundary layer and sometimes may also be due to Bragg-scattered refractive index  inhomogeneities. 
 TED WAVEFORM AND RESULTS IN A DIFFERENCE FREQUENCY  WHICH  ALTHOUGH FUNDAMENTALLY RELATED TO THE PHASE OF THE RECEIVED SIGNAL  IS A MEASURE OF ITS TIME DELAY AND HENCE RANGE OF THE TARGET 4HE DIFFERENCE FREQUENCY OR INTERMEDIATE FREQUENCY )&  MUST BE DERIVED FROM AN )1 MIXER PAIR IF THE INFORMATION EQUIVALENT TO A TIME 
 T. Ulaby, G. A. 
 The weights are computed offline, by assuming an a priori known covariance matrix M, and stored in a memory where a "menu" of weights is available to an operator or an automatic decision system.48 The idea of phase-only nulling in phased array antennas is appealing because the phase shifters are already available as part of the beam-steering system. Hence, if the same phase shifters can be employed for the dual purposes of beam steering and adaptive nulling of unwanted interferences, costly retrofitting could be unnecessary. However, phase-only null synthesis pre- sents analytic and computational difficulties not present when both the amplitude and the phase of the element weights can be freely perturbed.49'50 Nevertheless, ex- perimental systems have been tested with success. 
 BORNE 3!2 IS FORMED ALONG AN ARC 4HIS IMPOSES A SMALL BUT SIGNIFICANT INCREASE IN THE EFFECTIVE LENGTH OF THE SYNTHETIC APERTURE AND ALSO MODI 
 Acoustic absorber material is required at the crystal edges to reduce the reflections and, hence, the spurious responses. Figure 10.7 shows the limit that can be expected from an SAW device and shows that bandwidths up to 1 GHz and delays up to 200 jxs are achievable. The upper frequency limit depends on the accuracy that can be achieved in the fabrication of the interdigital transducer. 
 505–531, July 1985. 18. W. 
 These states are mixed using  inferred probabilities of the target transitioning from one motion model to another. As an example, consider radar tracking of a ballistic missile that undergoes distinct  phases of flight: boost, exo-atmospheric flight, and endo-atmospheric re-entry. Each of  these phases of flight has a distinct target model.57 During boost, the target is continually  accelerating and increasing speed. 
 I'llc clioice I~its I~ccri twtweeit electrical and hydrit~~iic syster~is. Electricill  ~1r ivcs ;tsc 1l1c W;\id I_cor\i\rct type 01. tl~ysistos I>ridgcs drivilig dc ntotors. 
  AND MIDDLE 
 8   OR SELECTION OF ONE AMONG SEVERAL RANGE 
 DOMAIN DATA   RESULTING IN A SET OF  . COMPLEX NUMBERS IN THE TIME 
 1219–1221. 4. Xie, P .; Zhang, M.; Zhang, L.; Wang, G. 
 I5.26d Composite response of the bank for five six-pulse filters.FIR RESPONSEFILTER RESPONSE (dB) . RELATIVE DOPPLER fd/PRF FIG. 15.28 Doppler filter bank of 68 dB Chebyshev filters. 
 Atthe receiving station, the various signals must beseparated and the data abstracted and put into usable form. The signals from the receiver arereceived byaswitching and decoding circuit similar tothat ofFig. 17,3 excspt forthesource oftheinput signal toV5b,Whose function will beexplained later. 
 Limiting in MTI radar.853-55 A limiter is usually employed in the IF amplifier just before the  MTI processor to prevent the residue from large clutter echoes from saturating the display. x%-dp  Ideally an MTI radar should reduce the clutter to a level comparable to receiver noise.  136INTRODUCTION TORADAR SYSTEMS Thiscanbesubstituted for(JcinEqs.(4.25)and(4.26)toobtainthelimitation totheimprove­ mentfactorcausedbyantenna scanning. 
 The input transducer has a wide bandwidth, and the receiving- array elements are spaced in a quadratic manner. Reversal of the spacing of the output-array elements will change the output from an up-chirp waveform to a down-chirp waveform. The delay slope is dependent on the output-array config- uration and the wedge angle. 
 The until today valid fundamentals of pulse Radar technology  had been laid down by Colonel B lair of the US Signal Corps in a patent from 1938.   8.2 Transmission Types of Pulse Radar   Pulse Radar instruments can, in principle, be divided into four categories, of which however, not all are suitable for each application.  The subdivision takes places once  after the existence  of the phase preservation between the transmitting and receiving signal according to:   - Coherent Radar (phase preservation),   - Incoherent Radar (arbitrary phase from pulse to pulse),   as well according to the pulse repetition frequency  € PRF =fp:  - Low PRF (< 1000 Hz),  - High PRF (> 30000 Hz). 
 Therefore, if the height of reference plane is inconsistent with the actual height of target in the scenes, the height di ﬀerence between the reference plane and the target will cause the decrease of imaging quality or even image defocusing because the range migration cannot be compensated correctly. To acquire the high precision ArcSAR image, the DEM of the scenes can be used to assist ArcSAR imaging. In this paper, we propose an interferometric DEM-assisted high precision imaging method for ArcSAR. 
 W. F.: Adaptive Arrays-An Introduction, Proc. IEEE, vol. 
 A., and E. J. Silha: Unique Features of the CHILL Radar System, Preprints, 18th Conf. 
 TO 
 Moore, “Trade-off between picture element dimensions and noncoherent averaging in  side-looking airborne radar,” IEEE Transactions on Aerospace and Electronic Systems , vol. 15,  pp. 697–708, 1979. 
 The term noise  factor is also used aftimes instead of noise figure. The two terms are now synonymous. RECEIVERS, IJISPLAYS, ANIJ IJUPLEXERS 345  The definition of noise figure assumes the input and output of the network are matched. 
 WAVE COMMUNICATIONS SYS TEMS v %33! 4ECH 2EPT   %2,   
 Cross-polarized returns from  volume scatterers with elements that are large compared with a wavelength are stron - ger than for surfaces, sometimes being only 3 dB down. Scatter depends on the dielectric constant, which depends on moisture content. Thus,  scatter from wet soils at angles off vertical is usually much higher than from dry soils. 
 SEC. 5.7] RANGE-MEASURING DOPPLER SYSTII.lT 139 plied with direct current orconceivably with alternating current of frequency above thepass frequency oftheaudio amplifier. 5.7. 
 Wartime Radar Development inthe United States. —Before the end of1940, thework onradar ofAmerican and British laboratories had been combined asaresult ofanagreement between thetwo governments for exchange oftechnical information ofamilitary nature. ABritish Technical Mission arrived inWashington inSeptember 1940 and mutual disclosures were made ofBritish and American accomplishments inradar uptothat time. 
 £  PS     [] 
 LAW DETECTORS ARE SIMILAR  DIF 
 An A-scope isuniversally used for observing radar signals and various circuit waveforms inaradar set during test and alignment. Itmay beeither part ofthe permanent installation ora piece ofportable test equipment. The laboratory analogue ofthe A-scope hascome tobeknown asa‘’synchroscope”; itisanindispensable tool inthe design and testing ofelectronic circuits.. 
 The variety of resolutions is supported by four bandwidths (225 MHz,  75 MHz, 37.5 MHz, and 18.75 MHz) through a programmable digital chirp generator.  The received data are downconverted to baseband, digitized to 8 bits (I and Q), and  quantized (by block-floating point means) to fewer bits (6 to 2), at the user’s option  within mode-dependent limits. All subsystems (save for the antenna) are dual-redun - dant. 
 82. Sensors 2019 ,19, 1920    (a2) ( b2)     (c2) ( d2)  Figure 11. Locally imaging results; ( a1) FFT algorithm with 32 pulses; ( b1) Relax algorithm with 32 pulses; ( c1) APES algorithm with 32 pulses; ( d1) KA-DBS algorithm with 32 pulses; ( a2) FFT algorithm with 64 pulses; ( b2) Relax algorithm with 64 pulses; ( c2) APES algorithm with 64 pulses; ( d2) KA-DBS algorithm with 64 pulses. 
 SECTION MISSILES BECOMES POSSIBLE USING THE SO 
 6.12 track ofrefraction conditions bytalking topilots ofaircraft seen onthe radar, and checking radar height readings with their altimeters. Combined PlanandHeightSystems. —Despite thespeed, convenience, and accuracy oftheelevation-scanning height finders just described, these sets are merely auxiliary toasearch radar. 
  
 A. A. Swartz et al., “Optimal polarization for achieving maximum contrast in radar images,”   J. 
 Another possible configuration providing multiple broadband beams uses parallel plates containing a wide-angle microwave lens37'38 (Gent, Rotman). Each port corresponds to a separate beam. The lens provides appropriate time delays to the aperture, giving frequency-invariant scanning. 
 V . A. Alebastrov, A. 
 and Y.S. wrote the manuscript. Y.L. 
 116--124, 1960.  9 l. This expression was suggested by Warren D. 
 In July 1939, an order for 24 transmitters and 24 indicator/receivers had been placed with Metropolitan-Vickers and Pye Radio, respectively [ 2] (power supply designs, antennas and installation details were unde ﬁned) but by the start of the war there were no ASV radars in service. Immediately the war began, the German U-boat ﬂeet was deployed, beginning hostile activities on 3rd September 1939. Th ere was an urgent need for long-range aircraft with ASV to patrol the North Sea, although the tactical priority at thattime was for monitoring surface ships. 
 Andrews14 has developed an optimization procedure for platform-motion com- pensation that rotates the phasors directly rather than by using a quadrature cor- rection. The procedure determines the antenna feed coeficients for two compen- sation patterns, one of which, C1(O), is added to the sum pattern 2(6) and fed to the undelayed canceler path and the other, C2(B), is added to the sum pattern and fed to the delayed path as shown in Fig. 16.20. 
 http://www.sinodefence.com/strategic/spacecraft/jianbing5.asp 17. http://www.caf.dlr.de/tsx/start_en.htm 18. http://www.space.gc.ca/asc/eng/satellites/radarsat2/inf_over.asp 19. 
 7) and a  separate chapter covers the phased-array antenna (Chap. 8). Devoting a single chapter to the  array antenna is more a rellection of interest rather than recognition of extensive application. 
 CHANNEL MODULES  EACH OF WHICH DRIVES EIGHT ELEMENTS )NDIVIDUAL MODULES ARE DESIGNED TO SLIDE INTO THE ARRAY STRUCTURE AND PROVIDE A HIGH 
 'The voltage waveforms of the two components of the transmitted signal  t-, and la2, may be written as  I*, .,. = sin (2?f1 t + 4]) (3.18~)  1727. = sin (2nf2t + 42) (3.186)  where 4, and 42 are arbitrary (constarit) phase angles. 
 Davis, J. D. R. 
  F2 IS THE )& CARRIER FREQUENCY  F   F2 IS ASSUMED  AND THE CARRIER PHASE  SHIFT IS    F P TT P ATT 
 TO 
 MENTED WITH A GAS DISCHARGE TUBE  IN WHICH A GAS IS IONIZED BY HIGH 
 Hall, W. M.: Antenna Beam-Shape Factor in Scanning Radars, IEEE Trans., vol. AES-4, pp. 
 MANCE AND PROPAGATION MODELING WITHIN A TERRAIN EFFECTS DOMINATED ENVIRONMENT 4HE ASSESSMENT SYSTEM REQUIREMENTS INCLUDED MODELING ALL NATURAL ENVIRONMENTAL EFFECTS  BEING QUICKLY EXECUTABLE  AND EXECUTING ON A -ICROSOFT 7INDOWS OPERATING SYSTEM PERSONAL COMPUTER !N EVALUATION OF THE VARIOUS PROPAGATION MODELS FOR THEIR STRENGTHS AND WEAKNESSES QUICKLY SHOWED THAT A HYBRID MODEL WAS THE ONLY ACCEPT 
 The other quantities inEq. (3)areofobvious significance ifitiskept inmind that the sub- script rrefers tothereply link. Inthepreceding paragraphs itwas assumed that thetriggering ofthe beacon and the intensity ofthe displayed reply depend onthe pulse powers ofthe two pulses. 
 to. Tomiyasu, K.: Phase and Doppler Errors in a Spaceborne Synthetic Aperture Radar Imaging the  Ocean Surface, IEEE lour. of Oceanic Engineering,\vol. 
 A small subreflector reduces aperture blocking, but it  Itas to be supported at a greater distance from the main reflector.  The geometry of the Cassegrain antenna is especially attractive for monopulse tracking  radar since the RF plumbing can be placed behind the reflector to avoid blocking of the  aperture. Also, the long runs of transmission line out to the feed at the focus ofa convcrltiorlal  parabolid are avoided. 
 Thompson, P. James, and P. Fox, “Calibration techniques for the RADARSAT-2  SAR system,” in Proceedings of EUSAR 2006 , Dresden, Germany, VDE Verlag, 2006. 
 The probability that the value of x lies within the finite range  from x 1 to x2 is found by integrating p(x) over the range of interest, or  Probability (x1 < X < X2) = f2  p(x) dx x, (2.9)  By definition, the probability-density function is positive. Since every measurement must yield  some value, the integral of the probability density over all values of x must be equal to unity;  that is,  f 00 p(x) dx = 1  -00 (2.10)  The average value of a variable function, </>(x), that is described by the probability-density  function, p(x ), is  (</>(x)).v = f 00 </>(x)p(x) dx  -00 (2.11)  This follows from the definition of an average value and the probability-density function. The  mean, or average, value of x is  (x)av = m1 = f 00  xp(x) dx  -00 (2.12)  t Probabilities are sometimes expressed in percent (0 to 100) rather than O to 1. 
 FINDER 7ITH A USER 
 it is found that there are limitations to high power. The necessity for attenuation or  severs in the structure, as mentioned above, tends to make the traveling-wave tube less efficient  than the klystron. The slow-wave structure can also provide a limit to TWT capability. 
 Sherwin, C. W., P. Ruina, and R. 
 Time (or range) +  (a)  nm n  Range -+  (c)  Figure 2.26 Multiple-tirne-around echoes that give rise to ambiguities in range. (a) Three targets A, B and  C, where A is within R,,,,, , and B and C are multiple-time-around targets; (b) the appearance of the  three targets on the A-scope; (c) appearance of the three targets on the A-scope with a changing prf.  THERADAR EQUATION 53 Inthisform.therangedoesnotdepend explicitly oneitherthewavelength orthepulse repetition frequency. 
 An example of such filter designs is presented next. Empirical Filter Design.  An example of an empirical filter design for a six-pulse  CPI follows. 
 OF 
 .}  It is usually inconvenient to draw a three-dimensional plot of the ambiguity diagram. For  this reason a two-dimensional plot is c,ften used to convey the salient features. Figure 11.10 is  an example of the two-dimensional plot of the three-dimensional ambiguity diagram corre­ sponding to the single pulse of Fig. 
 TORS ARE DEDICATED TO THE CALIBRATION OF THE ACTIVE ARRAY 4O CALIBRATE THE ARRAY IN RECEIVE MODE  TEST SIGNALS ARE ROUTED TO EACH OF THE RADIATORS USED FOR CALIBRATION  4HE SIGNAL  RECEIVED FROM A 42 MODULE IS COMPARED TO A STORED REFERENCE OBTAINED DURING FACTORY TEST   &)'52%    !CTIVE ARRAY CALIBRATION  TECHNIQUES  A  MUTUAL COUPLING   B  NEAR 
 Double-sideband noise can be translated to a single-sideband value by sub - tracting 3 dB. Unequal sideband power can only result from additive signals or noise  or correlated amplitude and phase noise components. Amplitude modulation (AM) of the STALO is typically not a significant factor as  it is usually at a lower level than the phase noise (at small offset frequencies from car - rier) and can be further reduced through limiting. 
 AROUND TRACKING CAPABILITY BECAUSE BEA 
 Andrews, G. A.: Airborne Radar Motion Compensation Techniques, Evaluation of TACCAR, NRL  Report 7407, Naval Research Laboratory, Washington, D.C., Apr. 12, 1972. 
 (21.23) can be considered a constant during a given transmission, al- though it will vary between transmissions. The integral that is the coefficient of the exponential term in Eq. (21.23) has the form of an autocorrelation function of g with itself. 
 -Pulse-to-pulse variation inthe repetition rate can pro- duce the same effect asunmatched delay lines. Thus the modulator should firerelative tothetrigger with avariation ofnot more than 2per cent ofthepulse length, or+ ~sec inthecase ofal-psec pulse. Finally, wehave toconsider theeffect ofvariation inpulse length. 
 ESTABLISHED CRITERIA 4HIS  UNFORTUNATELY  IS SELDOM DONE )T IS SUSPECTED THAT SOMETIMES THE DECISION AS TO WHICH 2& POWER SOURCE TO USE IS DETER 
 5and 6ofVol. 20and Chap. 13ofVol. 
 Sub-Image ship01 ship02 ship03 ship04 ship05 ship06 Original Image 2.97 2.42 2.81 2.44 2.33 1.49 DCT 3.11 2.50 2.85 2.48 2.37 1.50 PGA 3.25 2.54 2.88 2.56 2.38 1.53 Proposed Method 3.80 2.67 3.04 3.07 2.47 1.63 5. Conclusions By exploiting the ISAR technique based on fast minimum entropy phase compensation, a refocusing method for moving ships in SAR images is proposed in this paper. The basic procedures of refocusing in SAR images are built. 
 The optimum weight vector Wˆ  is determined by minimizing the  mean square prediction error, which equals the output residual power:  P E Z E VZ M = = − {|| } {|ˆ}2W V |T 2 (24.2) where Z is the system output. It is found that the following fundamental equation  applies:  Wˆ  = mM-1R (24.3) where m is an arbitrary constant value. The benefit of using the SLC can be measured  by introducing the jammer cancellation ratio (JCR), defined as the ratio of the output  noise power without and with the SLC:  JCRE V E VE V E VM MTM M= −=−{| | } {|ˆ| }{| | } {| | }2 22 2W V R R M RT −1* (24.4) By applying Eqs. 
 These are designated by 1 or O respectively. Thus the output of the  quantizer is a series of ls and Os. This is then separated into separate range cells by the range ··'"  First  threshold  Rodar Video Threshold  receiver detector Range gate  Quantizer -...- No. 
 FIG. 17.12 Postdetection STC levels. below the STC threshold, and a return in the main beam is above the threshold, such that the sidelobe discrete can be recognized and blanked from the final out- put but the target will not be blanked. 
 pp. 41-51, Jan., 1971.  176. 
 CENTERED,    2 - 24  22s 3HORT 
 It is not practical to use  a paraboloidal reflector with a single horn feed for aspect ratios greater than about 8: l,  although it is practical to use the parabolic cylinder for aspect ratios of this magnitude or  larger. Another advantage of the parabolic cylinder antenna is that the line feed allows better  control of the aperture illumination than does a single point source feeding a paraboloid. The  patterns in the two orthogonal planes can be controlled separately, which is of importance for  generating shaped beams. 
 L. Granatstein and I. Alexoff, High Power Microwave Sources , Boston: Artech House, 1987. 
 The  designer must then make subjective judgments or even arbitrary choices in order to arrive at  a compromise set of radar characteristics. Logical design of an entire radar system by com­ puter is therefore difficult and dangerous. Experience and educated guesses are still necessary  in many cases, just as is true of other engineering disciplines in which reasonable design  decisions must be made on the basis of incomplete information or conflicting constraints. 
 Distributed clutter, rain or chaff, is often a more serious interference with tar- get detection than noise. In passing through an optimum-bandwidth filter and optimum-bandwidth integrator, the echo is stretched in both range and angle; the clutter spectrum, being the product of the transmitted spectrum and the bandpass of the receiver, is narrower than either. As a result, the 6 dB two-way beamwidth and the 6 dB pulse width closely approximate the extent of the radar cell from which the "optimum" receiver accumulates clutter energy. 
 Section 3builds the signal model and describes the processing of the stack of images along elevation to yield resolution cells at di ﬀerent elevations, as in tomography. However, unlike tomography, in this mode the azimuth sidelobes occur at di ﬀerent elevations and can be eliminated by incoherent addition in elevation. The performance of the proposed method is related to system parameters in Section 4, and a set of design criteria is proposed. 
 However, the same variation in target  cross section would only cause a variation in range of a factor of 1.2 when the radar perfor-  mance is determined by receiver noise.  There are other significant differences in Eq. (13.8) that should be noted. 
 The size of the regions in which the error  currents cannot be considered independent is the correlation interval, C. The size or the  correlation interval affects both the magnitude and the directional characteristic of the spuri­ ous radiation that results from the presence of errors.  The first term of Eq. 
 For simplicity, let us assume that during this time  the targets do not leave their “range bins” of width c/2B. (This assumption will be dis - cussed in Section 17.5, “Range Migration.”) From the viewpoint of the SAR, the scene appears to be rotating with angular  velocity Ω = V/R. During the data collection, the total angle through which the scene  appears to rotate is ∆q  =  ΩT = VT/R. 
 KM SQUARE SNAPSHOT IMAGES OF THE OCEAN SURFACE  WHICH COULD BE PROCESSED ONBOARD OR LATER IN A GROUND FACILITY  TO ESTIMATE WIND SPEED AND DIRECTION FROM THE RADAR BRIGHTNESS AND WAVE PATTERN IN THE DATA 4HIS MODE WAS MOTIVATED BY A REQUIREMENT TO GATHER 3!2 
 With an antenna rotation rate of 15 RPM (1 revolution in 4 seconds or 90 scanning degrees per second), there is only 1 pulse transmitted each 0.090˚ofrotation.Thereareonly22pulsestransmittedduringthetimerequiredforthe antenna to rotate through its beam width. From the foregoing it is apparent that at the higher antenna rotation rates, the maximum ranges at which targets, particularly small targets, may bedetected are reduced.Beam Width Degrees per Pulse-----------------------------------------------------2.0° 0.036°---------------- 56 pulses== Beam Width Degrees per Pulse-----------------------------------------------------2.0° 0.090°----------------2 2= = pulses. 25FACTORS AFFECTING MINIMUM RANGE Pulse Length The minimum range capability of a radar is determined primarily by the pulse length. 
 FIGURE  2.14 Comparison of gaussian and exponential spectra on linear velocity scale ch02.indd   15 12/20/07   1:43:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 The advantages of the SAW device are its compact size, the wide band widths that can be attained, the ability to tailor the transducers to a particular waveform, the all-range coverage of the device, and the low cost of reproducing a given design. SAW pulse compression devices depend on the interdigital transducer finger locations or else the surface-etched grating to determine its bandpass character- istic. Figure 10.5 shows three types of filter determination approaches. 
 FIXED RADAR CONSPICUOUS OBJECTS INCLUD 
 BASED WAVEFORM IS SHOWN IN &IGURE   )T CAN BE NOTED THAT THIS AMBIGUITY FUNCTION IS MORE THUMBTACK 
 Hemsch, ed., Washington, DC: American Institute of Aeronautics and Astronautics, 1992,  Chap. 4.  2. 
 MEDIUM 02& IS BECOMING MORE PREVALENT IN MODERN AIRBORNE RADARS FOR AIR 
 Richter: Integrated Refractive Effects Prediction System (IREPS), Naval  Engineers Jo11mal, vol. 2, pp. 257 262, April, 1976. 
 114.Wcbster, A.J.:WindTorqucs onRotating RadarAerials,Marcolli Rev.,vol.28,pp.147-170, 2dqtr., 1965. 115.Vitale,J.A.:LargeRadomes, chap.5of"Microwave Scanning Antcnnas, vol.I."R.CHansen (cd.), Academic Press,N.Y..1964. 116.Blevis.B.c.:RainEffectsonRadomes andAntenna Rel1ectors, "Design andConstruction ofLarge Steerablc Aerials," 1EE(Lolldoll) Coll{erellce Puhlicatioll 110.21,pp.148-151, 1966. 
 GRAZING 
 TARGET  IMAGES FROM A SERIES OF INTERCEPTED )3!2 CHIRP PULSES  THUS PROVIDING 2& IMAGING DECOY CAPABILITY 4HE IMAGE SYNTHESIZER MODULATES THE PHASE SAMPLES FROM A PHASE SAMPLING $2&- THAT STORES INTERCEPTED )3!2 PULSES 4HE IMAGE SYNTHESIZER MUST ALSO SYNTHESIZE THE TEMPORAL LENGTHENING AND AMPLITUDE MODULATION CAUSED BY THE MANY REFLECTIVE SURFACES OF A TARGET AND MUST GENERATE A REALISTIC DOPPLER PROFILE FOR EACH SUR 
 Single-Target Tracking. Angle tracking can be identical to a conventional pulse radar using monopulse, sequential lobing, or conical scan. Monopulse is more difficult to mechanize because of the problem of phase and amplitude matching of the multiple receiver channels, but the problem can be mitigated by using self-calibration routines controlled by the radar computer. 
 BEAM PEAK RESPONSE ARE FEASIBLE BY USING ADVANCED TECHNOLOGY 3OMETIMES THE CONTROL OF SIDELOBE NOISE JAMMING BY USING ULTRALOW 
 If this assumption were not true, the filter which maximizes  the output signal-to-noise ratio would not be the same as the matched filter of Eq. (10.15). It  has been shown11 13 that if the input power spectrum of the interfering noise is given by  [N;(.{)]2, the frequency-response function of the filter which maximizes the output signal-to­ noise ratio is  ( 10.19)  When the noise is nonwhite, the filter which maximizes the output signal-to-noise ratio is  called the NWN (nonwhite noise) matched filter. 
 PASS  FOR THE 3PACE 3HUTTLE 2ADAR 4OPOGRAPHY -ISSION 324-   USING ANTENNAS ON THE SHUTTLE ITSELF AND ON THE SHUTTLES MANEUVERABLE ARM TO PRODUCE A COMPLETE $ MAP OF THE %ARTHS SURFACE BETWEEN  n  . LATITUDE AND  n 3 LATITUDENEARLY  OF THE SURFACE  WITH BEST VERTICAL ACCURACY  OF  METERS ON A  
 Since the Doppler frequency diﬀerence between the two targets is 20 Hz, conventional FFT method cannot distinguish them in the spectrum. The spectrum of the two targets is aliasing together and has just one peak in Figure 3c. However, by exploiting the prior knowledge of the spatial continuity, we can distinguish them well in the frequency domain as shown in Figure 3d. 
 Finite con- ductvity media,  no sources or  charges σ1 ,σ2≠∞ Js =Ms = 0 qes =qms = 0Medium 1 of  infinite  electric  conductivity σ1 =∞ ;σ2≠∞ qms = 0Ms = 0Medium 1 of  infinite  magnetic  conductivity H1t = 0 Js = 0 qes = 0 Tangential electric field Normal electric flux Tangential magnetic field Normal magnetic flux General Field intensity       n ×E2−E1 ( )=−Ms       n ×H2−H1 ( )=Js       n •D2−D1 ( )=qes       n •B2−B1 ( )=qms      n ×E2−E1 ( )=0       n ×H2−H1 ( )=0       n •D2−D1 ( )=0       n •B2−B1 ( )=0      n ×E2=0       n ×H2=Js       n •B2=0      n •D2=qes      n ×E2=−Ms       n ×H2=0       n •D2=0       n •B2=qms   Table 2.1  Boundary conditions on interfaces  . Radar System Engineering  Chapter 3 – The Radar Equation  13     3 The Radar Equation  3.1 Radar Equation for Point Targets   The general Radar equation found in Literature is derived for point targets. Point targets a re ob- jects whose dimensions D are small compared to the illumination R*  γBW (Range*Half -power  beamwidth) by the Radar at the target site. 
 Itislikely that two-cycle engines coupled to400-cps generators will beavailable inthe future inmany ratings; these units aremuch lighter and more compact than four-cycle engines with 60-cps generators ofequivalent rating. Itistrue that two-cycle engines have some disadvantages. They areoften more difficult tostart than the small four-cycle engines, and, because oftheir tendency tofoul exhaust ports and spark plugs, they are likely torequire more maintenance. 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 FIGURE 7.8  Optimum values of PN as a function of the sample size n and the probability of false  alarm a; Ricean distribution with S/N = 0 dB per pulse. ( after G. 
 RELATION TIME PERIOD OF THE SEA CLUTTER (E USED AN ANTENNA ROTATING AT UP TO  RPM AND  A 02& OF  +(Z 4HIS GAVE TWO CORRELATED PULSES PER BEAMWIDTH  BUT THE PULSES FROM THE NEXT SCAN   S LATER  WERE DECORRELATED FROM THE FORMER #RONY NOTED THAT THE RAPID SCANNING OF THE ANTENNA ALLOWED THE EYEBRAIN FUNC 
 /Ê +1-/" Ê  Ê,  
 Reduced gain may be desirable in a variety of  situations such as high clutter or high interference environments or in short range  modes. Fixed attenuation is often preferable to STC or clutter map control. High PRF  pulse doppler radars, for example, cannot tolerate STC due to the range ambiguity  of targets. 
 DE MM         3.2&! PDI &!PDI PD 
 ANCES TO THE TRANSISTOR 4HE COMMON MEDIUM FOR PROVIDING THIS FUNCTION IS A MICROSTRIP TRANSMISSION LINE -ICROSTRIP IS A QUASI 
 EDGE AMBIGUITY FUNCTION WITH CONTOURS THAT ARE  APPROXIMATELY ELLIPTICAL WITH A MAJOR  AXIS DEFINED BY THE LINE  V   @S  WHERE  @    o "4  IS THE ,&- SLOPE 4HIS PROPERTY INTRODUCES RANGE 
 ED-11. pp. 53-61, February, 1964. 
 In addition, the  (sin I))/$ function can be readily generated with a uniform aperture distribution. The  Woodward-Levinson synthesis technique consists in determining the amplitude and phase of  the uniform aperture distribution corresponding to each of the sample values and performing  a summation to obtain the required overall aperture distribution.  The aperture distribution may be found by substituting the antenna pattern of Eq. 
 Gunn and IMPATT diodes are the devices that offer the most promise for millimeter-wave solid-state operation. Brief descriptions of these device types and their associated technologies are given in the following subsections. Microwave Bipolar Power Transistors. 
 BASED RADAR TRANSMITTERS NATURALLY FALL INTO TWO CLASSES  INTIMATELY COUPLED WITH  THE ANTENNAS ARCHITECTURE )F THE ANTENNA IS ACTIVE  THEN THE TRANSMITTER AS WELL AS THE FRONT END OF THE RECEIVER  IS DISTRIBUTED OVER THE ARRAY )N THIS CASE  SEVERAL HUNDRED 42 ELE 
 J. R. MeteoroL Soc., vol. 
 At distance R from the antenna, the transverse dimension of the antenna beam is R times the angular beamwidth in radians. The range extent of the pulse is cr/2, where c is the speed of wave propagation in free space, 3 x 105 km/s, and T is the pulse duration in seconds. Most of the targets for which range prediction is ordinarily of interest are point targets, e.g., aircraft at appreciable distances from the radar. 
 1364-1370,  November, 1948.  64. Sche~rstcd, C. 
 £È°È  2!$!2 (!.$"//+  4HE ROUGHNESS OF SURFACES ESPECIALLY NATURAL ONES  IS DIFFICULT TO DESCRIBE MATH 
 BASED WEAPON CONTROL 3HORT RANGE ACCURATE RANGE  VELOCITY DATA -ETEOROLOGICAL 'OOD VELOCITY RESOLUTION -ISSILE WARNING 3HORT DETECTION RANGE VERY LOW FALSE 
 CALLED  O MODE THAT OCCURS  WHEN THE 2& FIELD CONFIGURATION IS SUCH THAT THE 2& PHASE ALTERNATES  O O RADIANS   BETWEEN ADJACENT CAVITIES 4HE ADVANTAGE OF THE  O MODE IS THAT ITS FREQUENCY CAN BE  MORE READILY SEPARATED FROM THE FREQUENCIES OF THE OTHER POSSIBLE MODES !N  . 
  D" SIDE 
 The F2 region is variable in both time and geographical location. The altitudes of the F2 region peaks are considered to lie between 250 and 350 km in the middle latitudes. The F2-region ionization shows marked day-to-day varia- tions and in general is not the regular sun follower that the E and Fl regions are. 
 NOISE CURVE SHOULD BE SELECTED WHEN  IT IS THE LARGEST AND WHEN THERE IS A PATH  THROUGH THE IONOSPHERE THE PATH WILL NOT EXIST FOR THE LOWER OPERATING FREQUENCIES IN THE DAYTIME 4HE ATMOSPHERIC NOISE RISES FROM LOW FREQUENCIES TO ABOUT  -(Z AND . Óä°{{  2!$!2 (!.$"//+  THEN RAPIDLY FALLS &IGURE  B IS FOR NIGHTTIME !LL THE CURVES ARE THE SAME AS IN  &IGURE A EXCEPT FOR ATMOSPHERIC NOISE !T  -(Z  THE NIGHT AND DAY LEVELS ARE  THE SAME BELOW  -(Z  THE NOISE DECREASES WITH DECREASING FREQUENCY IN DAYTIME AND INCREASES AT NIGHT !BOVE  -(Z  DAYTIME LEVELS ARE GREATER THAN THOSE AT NIGHT 4HESE EFFECTS CAN BE PARTIALLY EXPLAINED BY THE VERY LOSSY LONG 
 The same transmission line’ isused forboth thetransmitted and thereceived energy. Arotary joint must beinserted inthe line whenever more than afew degrees ofrotation ofanantenna are required. Such ajoint isalways installed with itsaxis coinciding with the axis ofthe corresponding degree offreedom. 
 !    /CTOBER    7 &ISHBEIN  3 7 'RAVELINE  AND / % 2ITTENBACH  h#LUTTER ATTENUATION ANALYSIS v 53 !RMY  %LECTRONICS #OMMAND  &ORT -ONMOUTH  .*  2EPORT .O%#/- 
 The position of the blips on the CRT is  a continuous indication of the distance of the aircraft  from the end of the runway, and thus the navigator or  observer with Babs is able to pass to the pilot a steady  flow of information which should bring the aircraft over  the edge of the airfield, at a comfortable height and  heading straight for the runway—and the pilot knows  that he can rely on it. The half-degree-wide beam of  Babs should bring the aircraft in not more than twenty  yards either side of the centre line of the approach end  of a runway 2000 yards long. Lights will then enable  . 
 It is well known in the fields of optics and acoustics that if either the source of oscillation  or the observer of the oscillation is in motion, an apparent shift in frequency will result. This is  the doppler effect and is the basis of CW radar. If R is the distance from the radar to target, the  total number of wavelengths). 
 = cutoff wavelength of guide Additional scan angles may be simulated by exciting other modes. The waveguide dimensions are chosen so that a radiating element or elements placed NORMALIZED GAIN (dB) TRIANGULAR GRID BASE = 1.0080 XALT = 0.5040 X a = 0.9050X b = 0.4OXEXPERIMENT TE.0TE10 and TE20 MULTIMODE GRATING-LOBE ANGLE (60°) TERMINATEDRADIATORS IMPEDANCE LOOKINGAT INFINITE ARRAY FROM 0= sirT'-fAC sin 6 = j- •- —• FOR TE10 MODE . in the waveguide sees mirror images in the walls of the waveguide that appear to be at the same spacing as the array to be simulated. 
 62. Salisbury, W. W.: The Resnatron, Electronics, vol. 
 Electronic invert- ers, although theoretically the most desirable, are practical only for power levels ofafew watts because oflow efficiency arising from tube plate-drop. Inverters are usually undesirable because they cannot be regulated. This leaves motor-alternators, dyrmmotors, and vibrators. 
 25. R. Hill, D. 
 Thelossofimprovement factorincreases withincreasing complexity ofthecanceler. Limiting in'thethree-pulse canceler willcausea15to25dBreduction inthe performance predicted bylineartheory.50 Afour-pulse canceler (notshown)withlimiting istypically only 2dBbetterthanthethree-pulse canceler inthepresence oflimiting clutterandofferslittle advantage. Thustheaddedcomplexity ofhigher-order cancelers isseldomjustified insuch situations. 
 24FACTORS AFFECTING DETECTION, DISPLAY, AND MEASUREMENT OF RADAR TARGETS FACTORS AFFECTING MAXIMUM RANGE Frequency The higher the frequency of a radar (radio) wave, the greater is the attenuation (loss in power), regardless of weather. Lower radar frequencies(longer wavelengths) have, therefore, been generally superior for longerdetection ranges. Peak Power The peak power of a radar is its useful power. 
 Every frame is the subaperture image indexed by the aspect angle. In WASAR, the backscattering from a complex target at high frequencies can be approximately modeled as a discrete set of the scattering centers [ 9].The scattering center can be described by the aspect-dependent amplitude and position [ 9]. The supports of the scattering centers overlap across the whole aperture. 
 PULSE INTERVALS 7HEN THE RATIO OF PULSE INTERVALS IS EXPRESSED AS A SET OF RELATIVELY PRIME INTEGERS  IE  A SET OF INTEGERS WITH NO COMMON DIVISOR OTHER THAN    THE FIRST TRUE BLIND SPEED OCCURS AT   6 6222 2 .".      !    p  !LL VELOCITY RESPONSE CURVES PLOTTED HEREIN PRESENT THE AVERAGE POWER RESPONSE OF THE OUTPUT PULSES OF THE CANCELER  FOR THE DURATION OF THE TIME ON TARGET FOR A SCANNING RADAR )F STAGGERING WERE USED WITH BATCH PROCESSING  SUCH AS IN A  PHASED ARRAY  THESE CURVES WOULD NOT APPLY FOR A SINGLE OUTPUT &OR EXAMPLE  IF THE STAGGER RATIO WAS  AND A THREE 
 Thefirstirregularity inthisparticular radiation pattern isthevestigial lobe,or"shoulder," onthesideofthemainbeam.Thevestigial lobe doesnotalwaysappearinantenna radiation patterns. Itcanresultfromanerrorinthe aperture illumination andisgenerally undesired. Inmostantennas thefirstsidelobe appears instead.Thefirstsidelobe issmeared intoavestigial lobeasinFig.7.1ifthephasedistribution acrosstheaperture isnotconstant. 
 NIQUE KNOWN AS THE  METHOD OF STOCHASTIC CONSTRAINTS  WHICH USES DIFFERENT RULES FOR  WEIGHT ADJUSTMENT  PRESERVING NOT ONLY THE GAIN BUT ALSO  TO A GOOD APPROXIMATION  THE PHASE OF THE CLUTTER RECEIVED VIA THE MAIN BEAM RESPONSE !LTHOUGH THESE MODERN SPATIO 
 Hence.. 444 7’11ERECEIVING SYS1’EM—RADAR RECEIVERS [SEC. 12.4 atriode isless noisy than apentode. 
 This fictitious plane wave - field    €  E s can be defined by the following transformation via the receiving field strength:  . Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 92        €   E s=4πR2 4πR02⋅ejβ(R−R0)⋅  E r(R) (11.6)   Note: R must lie in the far field of the emitter, however  € R0 not.    Clearly is    €  E sthe field strength with  € R0, brought about by an isotropic emitter at the origin,  which affects the receiving field strength     €  E r with radius R. 
 ,Ê,<  #ONDITIONS FOR BACKSCATTER NEAR GRAZING INCIDENCE ARE SUFFICIENTLY DIFFERENT FROM THOSE AT  STEEPER INCIDENCE THAT THEY MUST BE DESCRIBED SEPARATELY (ERE  WE DRAW UPON THE WORK OF "ILLINGSLEY  4HEY COLLECTED DATA OVER A WIDE RANGE OF TERRAIN AND UNLIKE MOST PRE 
 ENCE  THAT SIGNAL IS SUBJECTED TO INTERFERENCE MULTIPATH AND 2&)   WHICH IS DIFFERENT FROM INTERFERENCE AFFECTING THE TARGET ECHO PATH )F THE CORRELATOR OPERATES IN ITS LINEAR REGION  THE ECHO PLUS ITS INTERFERENCE CONVOLVED WITH THE REFERENCE PLUS ITS INTERFERENCE PRODUCES THE DESIRED ECHO WITH FULL MATCHED 
 The ability of the low-power remote sensing radars  to detect ships at over-the-horizon ranges, although modest, has been exploited in  some dual-purpose deployments. The principal virtue of HFSWR as an ocean surveillance radar lies in its ability to  detect small surface vessels and low-flying aircraft at ranges far beyond the visible  horizon. As with skywave radar, performance depends strongly on environmental and  target parameters, as well as radar design; the detection ranges cited in Table 20.3  provide some indication of capability against surface vessels and low-flying aircraft,  as claimed or reported for several established HFSWR systems. 
 The antenna is a fixed array with an integral radome producing four receive  beams and four transmit beams with a minimum of 70 dB of isolation between transmit and  receive. The one-way'beamwidths arerapproximately 2.5" (fore-aft) by 5" (lateral). The four  beams are displaced symmetrically'at an outward angle of 25" from the vertical. 
 Electrostatic tubes usually have two  pairs of plates, the vertical pair (which, remember, pull  or push the beam along a horizontal plane) being known  as the ‘X’ plates, and the others the ‘Y’ plates. These  terms arise, of course, from the familiar X and Y axes  of a graph. |  In a magnetic tube the sensitivity depends almost  entirely on the physical construction of the magnets,  but in an electrostatic tube there is quite a lot we can  do, in addition to securing a maximum change. 
  AND     0$    4HE OPTIMAL VALUE OF  0N  THE PROBABILITY OF  EXCEEDING  4 WHEN ONLY NOISE IS PRESENT  WAS CALCULATED BY $ILLARD AND IS SHOWN IN  &IGURE  4HE CORRESPONDING THRESHOLD 4 IS   4   R  
 and J. L. Green: The Detection and Identification of Birds in Flight. 
 TRACK  SLOPE OF THE SEA SURFACE CAUSED BY GRAVITY DEFLECTIONS OVER SPATIAL SCALES LESS THAN A FEW HUNDREDS OF KILOMETERS &IGURE   4HESE SLOPES ARE DERIVED FROM THE 33( MEASUREMENTS SUMMARIZED ABOVE   BUT THIS APPLICA 
 Figure 9. Comparison of two sampling methods. It is difﬁcult for the aircraft to maintain an ideal state due to factors such as airﬂow during ﬂight. 
 Mo,·ing cluuer and stationary radar. The discussion in this section has been concerned with  the oreration of an MTI radar when the clutter doppter-frequency was not at de but had some  finite value hccausc of tile motion of the vehicle carrying the radar. Thr. 
 S. Zrnic, “Clutter filtering and spectral moment estimation for doppler  weather radars using staggered pulse repetition time (PRT),” J. Atmos. 
 GAIN  TELECOMMUNICATIONS  ANTENNA  A STRATEGY SIMILAR TO THAT PIONEERED ON  -AGELLAN 3EVEN BEAMS  EACH AT DIF 
 usually at the output of the IF amplifier before the nonlinear second detector.  The receiver bandwidth B11 is that or the IF amplifier in most receivers. The available gain Ga is  the ratio or the signal out S0 to the signal in Si, and kT0 B11 is the input noise Ni in an ideal  receiver. 
 13. Martinez, et al., “Measurements and Modeling of Vertical Backscatter Distribution in Forest  Canopy,” IEEE Trans. on Geosc. 
 Zoning is hasc<l on the fact that a 360" change of phase at the aperture has  no effect on the aperture phase distribution. Starting with zero thickness at the edge of the lens,  the thickness or the dielectric is progressively increased toward the lens axis as in the design of  a normal lens. However, when the path length introduced by the dielectric is equal to a  wavelength. 
  TWO 
 # +U  $ 2 4HOMPSON  AND * 3ADOWSKI  h$IRECT NUMERICAL SIMULATION  OF ELECTROMAGNETIC ROUGH SURFACE AND SEA SCATTERING BY AN IMPROVED BANDED MATRIX ITERATIVE  METHOD  h*OHNS (OPKINS !0, 4ECH $IGEST  VOL   NO   PP n    # , 2INO AND ( $ .GO  h.UMERICAL SIMULATION OF LOW 
 VERTICAL THE  QUASI 
 :  = -20 c N J rural  ti, /x-5  Arizona mountainous x/'  Q  Arizona desert x- x- 2 -30 - 5 m C N J marshland x /x- / I  -40 2 U  RADAR CLUTIER 493 10 a iii"0 °-10b c:i QJ 0 c:-20 :J di0. <:-30Q U QJ '" '"'"._tj() !:u -50NJresidential1\,_~:PRhC;. n,ix ..x--\~~ ..-<*x~;-:.,.x uro Phoeni~ x ---x~Marsh '\ x .r".'----.,l(~ MIs NJruralx ,,~-:::::::=,x-;::.:;x~xDeser' ArizonadeserP----- ----=:-:~,," / Arizonamountainous ..~- --- NJmarshland .../X _______ x'" Delaware 8ay~x~ -60----..------.-,.--..-.L"-...':'_-L.--'_.L-L.LI .-"__--'__.L---l_.L--'--'--LJ,0 3° SO 10° 30° 60°90° Grazingangle (e) a o QJo -=-20<::J di0. 
 The additional parts necessary toseparate theradar and beacon data areshown inFig. 17.22. The cosine pulse isdelayed 30psec toform atrigger available onevery cycle, regardless ofwhether radar orbeacon video signals are being transmitted. 
 FORM (OWEVER  IT IS GENERALLY NECESSARY TO TRACK MANY MORE TARGETS THAN IS REQUIRED ON A SHIPBORNE RADAR  AND NORMALLY 643 HAS FULLY AUTOMATIC PLOT EXTRACTION AND TRACK INITIATION !LSO  MORE INFORMATION ON TRACKED TARGETS MAY NEED TO BE EASILY AVAILABLE -UCH OF THIS ADDITIONAL DATA CAN BE AUTOMATICALLY SUPPLIED BY !)3 4HE RADAR DATA  OFTEN HAS TO BE RELAYED MANY MILES  TO PERHAPS A NUMBER OF OPERATIONAL CENTERS )T  MAY NEED TO BE COMBINED  WITH DATA FROM A NUMBER OF RADAR HEADS  AND  THEREFORE  WILL  BE QUITE SYNTHETIC WHEN DISPLAYED ON OPERATORS SCREENS  REDUCING THE POSSIBILITIES OF INDIVIDUAL OPERATOR ADJUSTMENT %XTENSIVE DATA COMMUNICATIONS NETWORKS BECOME A CRITICAL ASPECT IN THE PERFORMANCE OF THE 643 (IGH RELIABILITY OF THE SYSTEM IS REQUIRED BECAUSE OF SAFETY  ENVIRONMENTAL PROTECTION  AND SECURITY ASPECTS ! TOTAL SYSTEM AVAIL 
 c.. W. -1'. 
 BAND v 4HE /HIO 3TATE  5NIVERSITY  !NTENNA ,ABORATORY  2EPORT .O  
 Next, consider a sine-wave  signal of amplitude A to be present along with noise at the input to the IF filter. The frequency  ThresholdOJ0' E o;- ~v, '6 c b'l'ci1 OJ ' no "iii>c toJTHERADAR EQUATION 25 TIr--------+ +----7k+I-------+,'!-- tk+21I Time--+- (2.26)Figure2.4Envelope ofreceiveroutputillustrating falsealarmsduetonoise. wheretkand7karedefinedinFig.2.4.Theaverageduration ofanoisepulseisapproximately thereciprocal ofthebandwidth B,whichinthecaseoftheenvelope detector isBIF.Equating Eqs.(2.24)and(2.25),weget 1V} 1[3=B 1Fexp2t/to AplotofEq.(2.26)isshowninFig.2.5,withV}/2t/toastheabscissa. 
 VIDE HIGHER SIDELOBES  BUT ONLY AT A LIMITED NUMBER OF LOCATIONS "OTH CORRELATED AND RANDOM SIDELOBES ARE OF CONCERN TO ANTENNA DESIGNERS #ORRELATED ERRORS ARE DISCUSSED IN 3ECTION  !NALYSES OF THE FAR 
 Further, in a high-PRF radar, especially at higher altitudes, the relative  amplitudes of the distributed sidelobe clutter and the discrete returns are such that the  discretes are not visible in the sidelobe clutter. The apparent radar cross section (RCS), sapp, of a sidelobe discrete with an RCS  of s is sapp = s GSL2, where GSL is the sidelobe gain relative to the main beam. The  larger-size discretes appear with a lower density than the smaller ones, and a model  commonly assumed at the higher radar frequencies is shown in Table 4.4. 
 A balance must be achieved. A short frame time limits the amount of  energy placed on target per dwell and lowers the single-scan Pd. A long frame time  allows the target to close in range more between revisits, thus lowering the benefit  of the accumulation. 
 385 386  coho, 105. 14 l  delay-line canceler, 104-114  digital processing, 1 J 9--125  doppler filter bank. 127  double delay-line canceler, 109  DPCA. 
 10.19. It is symmetrical about the origin, with N denoting the number of steps on each side. Table 10.10 lists stepped-amplitude func- tions optimized to yield minimum peak sidelobes for N = 2, 3, 4, and 5. 
 For example, with a relative velocity of  5 m/s (10 kt) thedoppler frequency shift at 1-pm wavelength is 10 MHz. A rapidly tuning laser  local osciflator or a large bank of IF filters are necessary to compensate for tlie /arge doppler  freqilericy sliift.  When the target is in tile far field of the laser antenna, and if the antenna beam is larger  tliari tlic target, tlie i~sual form of tlie simple radar equation of Sec. 
 SIZE FACETS AT FINITE WAVELENGTHS  AND CONSIDERING THE EFFECT OF WAVE 
 KT WIND   THIS IS ONLY ABOUT  FT  BUT FOR GALE 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar.  GROUND PENETRATING RADAR  21.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 The ground is modeled as a uniform lossy material with a relative permittivity of 13  and a conductivity of 0.005 S/m (Siemens/meter). 
 Fuzzy Clustering Algorithms for Unsupervised Change Detection in Remote Sensing Images. Inf. Sci. 
 The number of subpulses N required to achieve a thumbtack ambiguity diagram  with random frequency stepping is far less than with the phase-coded pulse. To achieve a total  bandwidth B, each subpulse need only have a bandwidth B/ N. The width of each subpulse is  thus N/B. 
 The sampling rate of the AID is determined by the radar signal bandwidth, and the number of  bits is set by the dynamic range desired. Motion compensation for a~imutll and range slip  (range walk) can be applied, as well as phase corrections for focusing. Semiconductor devices  are used for memory and arithmetic. 
 For given target, transmitter, and receiver altitudes the target must simulta- neously be within LOS to both the transmitter and the receiver sites. For a smooth earth these LOS requirements are established by coverage circles cen- tered at each site. Targets in the area common to both circles have an LOS to both sites as shown in Fig. 
 Multiple Independently Steered Beams.  Independent multiple beams may be  generated with a single beamformer by modifying both amplitude and phase at the  aperture. This can be seen from Figure 13.3, where, for example, two independent  ch13.indd   8 12/17/07   2:38:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The wavelength being determined, the antenna size was chosen. Togetasmuch range aspossible, this was taken aslarge aswas feasible without either (a)making the device impractically large or(b)getting the beam sosharp that atthe specified angular rate ofscan the beam would beonthetarget tooshort atime forthelistener tohear it. Both requirements ledtoadiameter inthe neighborhood of40in., the value finally chosen. 
 J. , vol. 41, pp.137–149, 1999. 
 81. no. 12. 
 25. E. G. 
 To facilitate the description of the crowded family of ECCM techniques (Sees. 9.6 through 9.10), a classification is attempted in Sec. 9.5. 
 In Figure 9, the horizontal axis and the vertical axis represent the azimuth samples and range samples, respectively. In Figure 10, the horizontal axis represents the azimuth frequency and the vertical axis refers to the corresponding amplitude of the target (converted to dB). The sub-images from left to right represent C1, C2, and C3 in turn. 
 Deformation Monitoring Accuracy Analysis We utilize the DEM obtained by interferometric ArcSAR to assist imaging, which can signiﬁcantly improve the imaging quality. The improvement of image quality also helps to improve the deformation monitoring accuracy. In this part, the contribution of the proposed method to the improvement of deformation monitoring accuracy is analyzed. 
 Radar loads areusually constant ornearly so,and hand control requires only occa- sional adjustment after,the equipment has come tonormal operating temperature. Theengines areusually provided with flyball-type speed governors which are satisfactory when well maintained, and keep the output frequency within arange ofabout 58to62cps. 14.12. 
 £Î°È  2!$!2 (!.$"//+  4HE ELEMENT MUST BE CHOSEN TO GIVE THE DESIRED POLARIZATION  USUALLY VERTICAL OR  HORIZONTAL 4HE SPECIAL CASE OF CIRCULAR POLARIZATION IS DISCUSSED BELOW )F POLARIZATION DIVERSITY IS REQUIRED OR IF AN ARRAY IS REQUIRED TO TRANSMIT ONE POLAR 
 This time the shadow is cast by the SAR itself. The portion of the  monument visible in the image is the south  side. Figure 17.9 shows the SAR image. 
 CIALLY IN PHASED ARRAYS !LTHOUGH AN INDIVIDUAL TRANSISTOR HAS RELATIVELY LOW POWER  EACH OF THE MANY RADIATING ELEMENTS OF AN ARRAY ANTENNA CAN UTILIZE MULTIPLE TRANSISTORS TO ACHIEVE THE HIGH POWER NEEDED  FOR MANY RADAR APPLICATIONS 7HEN SOLID 
 However,  the propagation characteristics of octave band radar signals in most earth materials remain  largely unaffected by dispersion In many instances, the potential variation in the velocity  of wave propagation over the frequency range of interest is small and can be ignored. Depth Resolution.  For traditional radar systems, it is accepted that two identical  targets can be separated in range if they are 0.8 of a pulse width apart. 
 , Munich, AMS, 2001, pp. 98–100. 165. 
 , AMS, Paris, 1991, pp. 752–755. 161. 
 They  expand at velocities ranging from 20 to 30 knots and can attain diameters of 30 km or more.  These ring-angels are associated with birds flying away from roosting areas. Angels can also be  caused by second-time-around echoes or large signals that enter the radar via the antenna  sidelobes. 
 IntheAEGISarrayaseparate high-power amplifier feedseachofthe32 Iransmitting subarrays. IIisalsopossible 10giveidenlical phase-sleering commands 10similar elements ineachsubarray, thusallowing simplification ofthebeam-steering unitandofthe interface cablingbetween thearrayandthebeam-steering unit.Thetermsubarray hasalso beenappliedtothearrayfeednetworks forproducing sumanddifference radiation patterns.52. 310 INTRODUCTION TO RADAR SYSTEMS  * Rad~ated - energy  -Input  (0) Phose sh~fters  1;igure 8.24 Example of a pillbox antenna (shown in (a)) used as a fwd for an array (b). 
 49. Kock, W. E.: Metallic Delay Lens, Bell System Tech. 
 From the manufacturer’s viewpoint the PPI presents  problems of alignment and so forth which can fairly  easily be corrected in a Type A display, but which may  cause errors in operation as the time-base itself is being  swung round the clock. Manufacturing problems, how-  ever, are not so serious that they detract in any way from  the amazing ingenuity and usefulness of PPI display,  which in itself was the first full attempt to make radar  ‘draw its own map,’ second by second.  . 
 713–728, 1995. 109. B. 
 Frequency Agility and Diversity." Artech House. Inc .. Dedham. 
 detector were linear while the video integrator had a square-law characteristic, the combina-  tion of detector and integrator would be considered square law.  In the following we shall derive the optimum form of the secondadetector  la^.^^*^^  Assurne that there are rl independent pulses with envelope amplitudes u,, v2, . , on available  from the radar receiver. 
 The number of taps equals the  number of pulses to be integrated. The outputs from each of the taps are tied together to form  the sum of the previous n pulses. One of the advantages of this integrator is that any type of  weighting may be applied to the individual pulses by simply inserting the proper attenuation  at each tap of the delay line. 
 Parabolic  reflector  ~  \  \  \  Displaced \  from original /1(  porobolic ./ \  con lour _ __- \ RADAR ANTENNAS 259  Figure 7.24 Cosecant-squared antenna  produced by displacing the reflector  surface from the original parabolic  shape.  design in the orthogonal plane. The parabolic cylinder antenna fed from a line source is  convenient for obtaining independent control of the patterns in the two orthogonal planes. 
 For a 15-kn wind, this is only about 3 ft, but for gale-force winds of 40 kn it rises to over 20 ft, which is a rather formidable sea. Looking at the sea, an observer might describe what he or she sees in terms of a subjective state of the sea, e.g., "smooth," "rough," "terrifying!" If these de- scriptions are listed in order of severity and assigned numbers, these numbers define a sea state. A similar numerical scale exists for wind speeds, the Beaufort wind scale, with numbers about an integer higher than the corresponding sea state. 
 Coherence  implies two constraints: spatial and temporal. The spatial constraint applies to the spac - ing between the orbital passes. Ideally, the radar wavelength projected onto each area  of the surface must be the same from both orbits. 
 2.9 must be reduced somewhat because part of the total antenna pattern is not then directed at the sky. The reduction factor is (1 - TagITtg), where Tag is the ground noise-temperature contribution to the total antenna temperature and Ttg is the effective noise temperature of the ground. If a is the fraction of the solid-angle antenna power pattern subtended by the earth, then Tag = a.Ttg. 
 The coupling from several elements to a typical central element, element 00, is shown in Fig. 7.12. The Cmn pq are mutual-coupling coefficients relating the voltage (am- plitude and phase) induced in the mnth element to the voltage excitation at the . 
 For mechanically rotating radars, all that is  usually done is that the tracking gates are fed back to the signal processor. The tracking  gates are always used to facilitate the association process and may be used to lower  the detection threshold within the gate and/or modify the contact entry logic within the  gate (e.g., modify rules governing clutter maps). The interaction of the tracking system with a phased array radar is much more sig - nificant. 
 Pseudorandom phase-coded waveforms40andrandom noise waveforms41.42mayalsobeappliedtoCWtransmission. Whenthemodulation periodislong, itmaybedesirable toutilizecorrelation detection insteadofmatched filterdetection. 3.4AIRBORNE DOPPLER NAVIGATION43-56 Animportant requirement ofaircraftflightisforaself-contained navigation systemcapableof operating anywhere overthesurfaceoftheearthunderanyconditions ofvisibility orweather. 
 D is the antenna diameter, p, is the aperture efficiency, C is the correlation interval  of tlic error, arid It ccjtrals sit1 0. 'I'lic rriean square phase error is assumed to be gaussian. The  angles 0, 4 are those usually employed in classical antenna theory and are defined in Fig. 
 16·29•30•38 In this form of pulse compression, a long pulse of  duration Tis divided into N subpulses each of width r. The phase of each subpulse is chosen to  be either O or n .radians. If the selection of the 0, n phase is made at random, the waveform  approximates a noise-modulated signal with a thumbtack ambiguity function, as in  Fig. 
 Anderson20.1 20.1  Introduction / 20.1 20.2  The Radar Equation / 20.5 20.3  Factors Influencing Skywave Radar Design / 20.7 20.4  The Ionosphere and Radiowave Propagation / 20.13 20.5  Waveforms for HF Radar / 20.21 20.6  The Transmitting System / 20.23 20.7  Radar Cross Section / 20.26 20.8  Clutter: Echoes from the Environment / 20.29 20.9  Noise, Interference, and Spectrum Occupancy / 20.40 20.10  The Receiving System / 20.45 20.11  Signal Processing and Tracking / 20.49 20.12  Radar Resource Management / 20.54 20.13  Radar Performance Modeling / 20.55   Appendix: HF Surface Wave Radar / 20.70 Chapter 21 Ground Penetrating Radar David Daniels21.1 21.1  Introduction / 21.1 21.2  Physics of Propagation in Materials / 21.6 21.3  Modeling / 21.13 21.4  Properties of Materials / 21.18 21.5  GPR Systems / 21.20 21.6  Modulation Techniques / 21.21 21.7  Antennas / 21.24 21.8  Signal and Image Processing / 21.30 21.9  Applications / 21.35 21.10  Licensing / 21.39. Chapter 22 Civil Marine Radar Andy Norris22.1 22.1  Introduction / 22.1 22.2  The Challenges / 22.3 22.3  International Standards / 22.7 22.4  Technology / 22.10 22.5  Target Tracking / 22.17.     xi 22.6  User Interface / 22.19 22.7  Integration with AIS / 22.23 22.8  Radar Beacons / 22.25 22.9  Validation Testing / 22.28 22.10  Vessel Tracking Services / 22.29   Appendix The Early Days of CMR / 22.31   List of Maritime Radar-related Abbreviations / 22.33   Acknowledgments / 22.34 Chapter 23 Bistatic Radar Nicholas J. 
 In a practical application, the two sequences must be separated in time, frequency, or polarization, which results in decorrelation of radar returns so that complete sidelobe cancellation may not occur. Hence they have not been widely used in pulse compression radars. FIG. 
 a. Please calculate the decreasing the  range of the radar (without consideration of the  fluctuation loss) according the radar equation.                 b. 
 Both claims can be debated. Although only two receivers are  required instead of the three used in a monopulse tracker, the mechanical rotation of the two  QJ g 4.0 ..... ~-0 o II  .~~3.0 .,.- L ~ e >  I.... 
 TIVE INTERFERENCES SUPPRESSION v  0ROC )%%%  )NT 2ADAR #ONF   !LEXANDRIA 6!   53!   -AY n    PP n. 
 RELATED PARAMETERS AND  P4 AND P2  IN CALCULATIONS OF TRANSMITTER 
 The noise level can be specified either  as an rms power in a specified bandwidth or as a noise power spectral density . System Noise.  The system noise level is the combined antenna and receiver noise. 
 ARRAY !DAPTIVITY WOULD TRY TO EQUALIZE THE NOISE BETWEEN CHAN 
 is a method for generating niilltiple receiving beams at a single frequency and can be  corisidered Inore like the stacked-beam radar than a frequency-scan height finder.  Interf~ronieter.~~ " An i~iterferorneter consists of two individual antennas spaced so as to  ohtaiti a tiarfow hcarnwidtii for accut'atc angle tneasuretnent. The phase difference between tlic  signals of the two antenna elernents ol the interferometer provides the elevation angle, as giveti  I>y I'q. 
 As shown in Figure 14.5, the broadside echo of a metal wire exhibits reso - nances at odd multiples of a half wavelength, with plateaus of nearly constant return  between the resonant peaks. These plateaus rise with increasing dipole length and  become less distinct as the dipole becomes thicker and longer. They eventually disap - pear when the dipole becomes fat enough and long enough. 
 Nozette, “Mini-SAR: An imaging radar  for the Chandrayaan-1 mission to the Moon,” Paper 1153, Proceedings, Lunar and Planetary  Science XXXVI , Houston, TX, vol., 2005. 111. R. 
 However, at 60 ° scan the compensation on one-half of the array assists  in keeping the gain comparable to that of a parallel feed. From the viewpoint of gain  reduction, the criterion for a center-fed array is  Bandwidth(%) beam width () (CW) = °λ λg  where lg is the waveguide wavelength. However, from the viewpoint of sidelobes, this criterion may be unacceptable. 
 3RADAR PROPAGATION CHARACTERISTICS THE RADIO WAVE To appreciate the capabilities and limitations of a marine radar and to be able to use it to full advantage, it is necessary to comprehend thecharacteristics and behavior of radio waves and to grasp the principles oftheir generation and reception, including the echo display as seen by theobserver. Understanding the theory behind the target presentation on theradar scope will provide the radar observer a better understanding of the artand science of radar interpretation. Radar (radio) waves, emitted in pulses of electromagnetic energy in the radio-frequency band 3,000 to 10,000 MHz used for shipborne navigationalradar, have many characteristics similar to those of other waves. 
 TIVE PROCESSING IN MILITARY APPLICATIONS WITH CELEBRATION OF " &RANKLIN MEDAL TO    " 7IDROW FOR PIONEERING WORK ON ADAPTIVE SIGNAL PROCESSING  SEE %TTER ET AL 4HE  THEORY AND APPLICATION OF ADAPTIVE ARRAY PRINCIPLES TO RADAR IS WELL ESTABLISHED FOR A LOOK TO POPULAR PUBLICATIONS SEE  FOR INSTANCE  (AYKIN AND 3TEINHARDT   3MITH   AND &ARINA ET AL 4HE BASIC RESULT IS GIVEN BY THE EXPRESSION OF THE OPTIMUM SET  OF WEIGHTS   }7- 3 
 Air Power in the Defence  of Australia , Australian National University, Research School of Pacific Studies, Strategic and  Defence Studies Centre, Canberra, Australia, July 14–18, 1986.  9. J. 
 CLUTTER CONTROL IS USED TO ADJUST THE TRANSITION RANGE .OWADAYS  THE FORM OF THE 34# CURVE AND THE EFFECTS OF THE MANUAL CONTROL ARE BASED ON THE PRACTICAL EXPERIENCE OF INDIVIDUAL MANUFACTURERS  WHICH CONTRIBUTES GREATLY TO THE ACTUAL EFFECTIVENESS OF A PARTICULAR RADAR IN SEA CLUTTER %VEN UNDER MANUAL CONTROL  THE DETAILED SHAPE OF THE 34# CURVE MAY HAVE A COMPLEX ADAPTIVE ELEMENT TO IT  IN ORDER TO OPTIMIZE THRESHOLDS OVER A BROADER RANGE 5NDER AUTOMATIC SETTINGS  THRESHOLDING BECOMES INCREASINGLY SOPHISTICATED BUT  OFTEN STILL ALLOWS SOME MANUAL OPTIMIZATION 4HE CURVE MAY ADAPT TO INTERNAL CALCULA 
 Any use is subject to the Terms of Use as given at the website. The Radar Transmitter.  THE RADAR TRANSMITTER  10.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 An experimental implementation using data collected on an operational radar with  a CFA transmitter showed that “the TNC technique can improve radar detection of  targets in clutter by 15 dB or more.” 10.7 GRID-CONTROLLED TUBES The grid-controlled tube is a modern version of the classical triode or tetrode vacuum  tube that dates back to the early years of the 20th century. These devices employ a  cathode to generate electrons, one (for a triode) or two (for a tetrode) control grids,  and an anode to collect the electrons. 
 Any use is subject to the Terms of Use as given at the website. Civil Marine Radar.  CIVIL MARINE RADAR  22.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 In previous years, ships were required to have a radio officer, who could carry out  radar repairs at sea. This is no longer the case. 
 ANTENNA GAIN AND RECEIVING 
 Vertically  polarized waves are reflected better from vertical structures such as tree trunks, at least  when the wavelength is comparable or larger than the trunk diameter. If the geometry of two radar targets were the same, the returns would be stronger  from the target with higher complex permittivity because larger currents (displacement or  conduction) would be induced in it. Because identical geometries with differing permit - tivities do not occur in nature, this distinction is not easy to measure. 
 This sweeps the local-oscillator frequency over arange that may beatenth ofthe half-power bandwidth ofthe cavity. The crystal output then has an amplitude modulation ofmagnitude proportional tothe slope ofthe cavity resonance curve atthefrequency inquestion. The phase ofthis amplitude modulation depends onwhether the slope ispositive ornega- tive. 
 One of the factors that is often misleading is the usual picture of an array as a singlr:  radiating face of relatively modest size. A single array antenna can scan but a limited sector;  t-45" in each plane is perhaps typical. Four or more faces might therefore be necessary for -  hemispherical coverage. 
 This corresponds to shaping an array pattern with phase only and may represent a severe problem if sharp pattern skirts are required. It can be avoided with extended feeds. Multiple Beams and Extended Feeds.19-21 A feed at the focal point of a parabola forms a beam parallel to the focal axis. 
   -%4%/2/,/')#!, 2!$!2   £°ÓÎ )F WE MULTIPLY THE NUMERATOR AND DENOMINATOR BY RV  %Q  BECOMES   VAR  V 44V VV F  LS PSS PS       4HUS   IT IS SEEN THAT THE VARIANCE OF THE MEAN VELOCITY ESTIMATE  }V IS DIRECTLY PROPOR 
 MERRILL SKOLNIK Baltimore, Maryland. £°£ÊÌÀ`ÕVÌÊ>`Ê "ÛiÀÛiÜÊvÊ,>`>À  iÀÀÊ- £°£Ê , ,Ê Ê , 
 The RCS has aspect sensitivity but strongly depends upon the target's gross dimensions. For an aircraft the span of the wings, the fuselage length, the tail and elevator span, the vertical stabilizer and rudder height, and their relative locations are the features that determine the RCS. Target shaping of a scale size much less than a wavelength will have little effect. 
 Note that the duration of the refer- ence waveform should exceed the duration of the received waveform by the range processed interval, or else an SIN loss will occur. A stretch processor with unequal-frequency-slope waveforms requires pulse compression of the residual linear FM. A linear FM with a frequency slope of ain - OR occurs at the target's range. 
 NUMBER AND DIRECTION  THE PRINCIPAL hFIRST 
 V . Oppenheim and R. W. 
 The rotary waveguide feed was made radial forcompactness, resulting in the arrangement ofthe horn, chokes, and annular aperture shown in Fig. 9.31. The absorbing septum shown inthis figure was introduced to reduce theamount ofambiguity caused byadouble beam and toimprove. 
 Thus,inthevicinityofbroadside (00~0),thebandwidth available forpulsecom­ pression isDIn~\/1[).Thefrequency-modulated signaloccupying abandequaltoIIIDcanbe compressed inapulsecompression filtertoproduce anarrowpulseattheoutputofthefilter. Thisthenisonemethod forcombining frequency scanwithpulsecompression, wherethe angularresolution depends ontheantenna beamwidth andtherangeresolution depends on thegrouptimedelayID' Thefrequency-scan technique iswellsuitedtoscanning abeamoranumberofbeamsina singleanglecoordinate. Itispossible tousethefrequency domain toproduce aTV(raster) typeofscanintwoorthogonal angularcoordinates byemploying anarrayofslightlydisper­ sivearraysfedfromasinglehighlydispersive array.(Thesinglesnakelineinthiscaseismuch longerelectrically thanthesnakelinesfeedingalineararray.)Thesinglesnakelinepasses through severalmodesintraversing thefrequency band.Ithasbeensaidthata90by20° sectormightbepossible usinga30percentfrequency band.67Oneofthedisadvantages ofthis formoftwo-dimensional frequency-scan arrayisthatitrequire~ awidebandandisvery limitedinsignalbandwidth, muchmoresothanthearraywhichsteersinonedimension only. 
 The parameters of the layers are given  in Table 21.3. FIGURE 21.7  Physical layout of GPR system ( Courtesy IEE ) Antenna at height H  Air / soil interf ace  Target at range r and diameter from 50mm to 500mm  ch21.indd   14 12/17/07   2:51:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Widrow, B., P. E. Mantey, L. 
 This cor - responds to a speed of 325 kt if the system has a PRF of 1000 Hz and a 10-ft antenna  aperture. For a single-delay system, the displacement has to be held to 1.1% for a   30 dB performance limit. 3.5 PLATFORM-MOTION   COMPENSATION ABEAM The deleterious effects of platform motion can be reduced by physically or electroni - cally displacing the antenna phase center along the plane of the aperture. 
 It is not usually applicable to aircrafl  targets, but it can sometimes be applied to radars designed to detect extraterrestrial targets  such as satellites or astronomical bodies. In these cases, the transmitted pulse width is rela­ tively wide and its spectrum is narrow. The high speed of extraterrestrial targets results in  doppler shifts that are usually significantly greater than the spectral width of the transmitted  signal. 
 39. Goetz, L. P., and W. 
 Phillips17 derived this asymptotic behavior on dimensional grounds, and a widely used  simplification, obtained by replacing the smooth peak in Figure 15.1 by a sharp cutoff,  is generally referred to as the Phillips Spectrum :  W(K) = 0.005 K−4  K > g/U2   = 0     K < g/U2 (15.4) where the cutoff wavenumber corresponds to the frequency fm of the peak in Eq. 15.3.  Opposed to this highly simplified form are increasingly complex spectra based on more  careful empirical studies18 as well as more sophisticated theoretical considerations.19 In discussing the characterization of the sea surface by its spectrum, it must be kept  in mind that the spectrum is a highly averaged description of how the energy  of the sur - face is distributed among the wavenumbers, or frequencies, of the waves present on it. 
 Both have been used for microwave phase shifters. A typical  spinel ferrite is NiFe204• In addition to nickel, compositions of magnesium-manganese and  lithium have been used. A common garnet is Y 3Fe5012, yttrium iron garnet (YIG). 
 In late 1941, the Radiation Laboratory had started the design of a set called DMS.1000, which closely met the requirements of Coastal Command (see chapter 3). In December 1941, at the same time as work on the experimental installation of ASV Mk. III on a Wellington was completed by TRE, testing of the ﬁrst installation doi:10.1088/978-1-6432-7066-1ch8 8-1 ªMorgan & Claypool Publishers 2018. 
 Asaresultofthecylindrical geometry, theradiation pattern isonlypartially separ­ ahleinspatialcOOldinates. (IIcanheconsidered astheproduct ofaring-array patternanda lincar-array pattern.) TIleazimuth patternofavertical cylindrical arraychanges withboth azimuth andel~vation asthebeamisscanned inelevation. Thefar-outsidelobes ofacylindri­ calarrayaregenerally largeandbroadinangle,ascompared tothoseofaplanararray.The designofertkient feednetworks, thephaseandamplitude controldevices, distributed trans­ mitterand/orreceiver modules, andthecontrolalgorithms andlogicareotherproblem areas. 
 For linear rheological models, a qualitative analysis of the material is initiallycarried out, then the corresponding rheological state function is constructed, which quantitatively represents the functional relationship between the strain of soft soil material and physical variables (i.e., viscosity, elastic modulus, and time). These are mainly based on the series-parallel connection of basic mechanical components (i.e., Burgers model, Kelvin model, and Maxwell model, among others). This kind of model can easily and intuitively express complex mechanical properties, which is helpful for conceptually understanding the elastic and visco-elastic properties of soft soil deformation. 
 (7.18) that the matched- element power pattern is GJG) = 4ir — cos G (7.21) NK2 and the normalized radiation amplitude pattern of the (matched) element or (matched) element pattern is Ee(Q) = VcosG (7.22) . It has already been noted that the matched-element pattern is very similar to the obliquity factor '/2(1 + cos 6) and differs markedly only near endfire, where the number of elements begins to matter.42 For a given element spacing s the total number of radiators N in the area A is N = AIs2, and Eq. (7.21) gives G,(0) = 4TT £ [COS 0IAJ When the element spacing is s = A./2, then the power pattern of an element that is perfectly matched at all scan angles is G,(6) = TT cos 0 (7.23) and the peak antenna gain in the direction of scan, 00, is G(O0) = TrAfT1 cos 00 (7.24) where the efficiency term TI accounts for losses and for a nonuniform aperture distribution. 
 GE-12, pp. 70-77, April, 1974. 514 INTRODUCTION TO RADAR SYSTEMS  54. 
 Gunn, K. L. S., and T. 
 For example, if·  the bandwidth were 1 MHz, a value of 10 log (V}/2ij, 0) = 12.95 dB results in an average  false-alarm time of 6 min, while a value of 14.72 dB results in a false-alarm time of 10,000 h.  Thus a change in the threshold of only 1.77 dB changes the false-alarm time by five orders of  magnitude. Such is the nature of gaussian noise. 
 TO 
 POWER WIDTHS 2EAL PULSES CANNOT BE RECTANGULAR AFTER PASSING THROUGH REAL TRANSMITTER  ANTENNA  AND RECEIVER BANDWIDTHS 4HE TRANSMITTING 
 !IR -ISSION 0ROFILE  *UST AS WITH AN AIR 
 Differentiation of Eq. (7.34)  shows that the maximum gain corresponds to a wavelength  At this wavelength the gain will be 4.3 dB below what it would be in the absence &errors. The  maximum gain is then  The gain of an antenna is thus limited by the mechanical tolerance to which the surface can be  constructed and maintained.lo2 The most precise reflector antennas seem to be limited to a  precision of not much greater than about one part in 20,000, which from Eq. 
 The azimuth indicator for the Leigh Light operator (see ﬁgure 4.14) was considered a de ﬁnite advantage. It was noted that it was very dif ﬁcult for a schnorkel to be seen at short range at night using the Leigh Light and it was recommended that the blind bombsight wouldbe the best method for attacking schnorkels. It was noted that to lock on to a small target such as a schnorkel it had to be at least 1 ½ miles clear of the sea returns. 
 T. Rusch, “Scattering from a hyperboloidal reflector in a Cassegrainian feed system,” IEEE  Trans ., vol. AP-11, pp. 
  D" TO    D" 4HE EFFECTIVE BEAM  FOOTPRINT AFTER DOPPLER PROCESSING  IS  ^ KM ALONG TRACK AND  ^ KM ACROSS TRACK  .OMINAL 3.2 WITH RESPECT TO THE SURFACE RETURN IS IN EXCESS OF  D" )NSTRUMENT MASS IS ^ KG  INPUT POWER IS  ^ 7 3(!2!$ MEASUREMENTS STARTED LATE  ONLY WHEN  THE -2/ ORBIT WAS CIRCULARIZED AFTER SIX MONTHS OF AEROBRAKING. £n°ÈÓ  2!$!2 (!.$"//+  3%,%.% 4HE *APANESE LUNAR MISSION  3%,%.%  INCLUDES A  -(Z ,UNAR  2ADAR 3OUNDER ,23  AS ONE OF ITS  PAYLOAD INSTRUMENTS 4HE ORBIT IS CIRCULAR  AT  
 106. R. A. 
  SO THESE RESONANT OCEAN WAVES HAVE A WAVE 
 97. Shrad!;!r, W.W.: MTI Radar," Radar Handbook," M. I. 
  AND QUADRATURE 
 TION  AND NORMALLY CONSIST OF RADIATING PATCHES  RATHER THAN PRINTED DIPOLES (ORIZONTAL APERTURES OF  AND  MM ARE COMMON 0RINTED TECHNOLOGY IS NOT GENERALLY USED FOR SHIPBORNE ANTENNAS SLOTTED WAVEGUIDE ARRAYS REMAIN THE COST 
 30 HOW RADAR WORKS  workers it has become an engineering enterprise of great  diversity and magnitude, and it is still growing.  Let us now step aside from this race of progress and  study the basic principles of radar itself.  . 
 ORBIT THER 
 4.17  RF Tube Power Capa bilities  ..............................  4.21  4.5 Combining and A rraying  .........................................  4.22  Hybrid Combining (or Magic T)  .......................... 
 HORIZON RADAR ARRAY  CALIBRATION USING ECHOES FROM IONIZED METEOR TRAILS v  )%% 0ROC 2ADAR  3ONAR  AND .AVIGATION    VOL   PP n  *UNE   ) 3 $ 3OLOMON  $  ! 'RAY  9 ) !BRAMOVICH  AND 3 *  !NDERSON  h2ECEIVER ARRAY CALIBRATION  USING DISPARATE SOURCES v )%%% 4RANS !NT 0ROP  VOL   PP n  -ARCH   ' * &RAZER AND 9 ) !BRAMOVICH  h1UANTIFYING MULTI 
 LOBE SUPPRESSION  THE SQUARE GEOMETRY REQUIRES  APPROXIMATELY  MORE ELEMENTS %LEMENT 
 Saka and E. Yazgan, “Pattern optimization of a reflector antenna with planar-array feeds and  cluster feeds,” IEEE Trans. Antennas Propagat ., vol. 
 With this the ambiguity d e- velops if the phase shift through Doppler in a pulse interval becomes larger than 2 π.  With the non- coherent pulse Radar, i.e. no phase reference from pulse to pulse, the radial velocity is measured  over the change of distance, however substantially more inaccurately. 
 Switched-line configurations rely on FET  switches to switch lengths of transmission line in and out of the circuit and are  typically used for higher frequencies where less chip area is needed. Loaded-line  configurations use the switched FET parasitics as circuit elements to introduce the  necessary phase changes. The typical processing and construction sequence for a MMIC chip is fairly similar  among the GaAs foundries (Figure 11.20). 
 The maxima at 22.2 and 60 GHz are due to water-vapor and oxygen absorption resonances; see Fig. 2.19.) (From Ref. 13.)FREQUENCY (MHz)NOISE TEMPERATURE (K) . 
 _ COS OLYS <)) = tan l —cos axs The angle of scan B is determined by the distance of the point (cos OLXS, cos ays) from the origin. This distance is equal to sin 0. For this reason a representation of this sort is called sin 6 space. 
 spurious signals which degrade performance may be generated. For example, if main-beam clutter saturates, spurious frequencies can appear in the doppler passband normally clear of main-beam clutter and generate false-target reports. An AGC function is often employed to prevent saturations on either main-beam clutter in search or the target in single-target track mode. 
 TIONED  &ARADAY ROTATION RESULTS IN VARYING INCIDENT POLARIZATION  SO OVER TIME A TARGET WILL EXPERIENCE BOTH FAVORABLE AND MISMATCHED POLARIZATION  WITH RESULTANT FADING OF THE SCATTERED SIGNAL /F COURSE  ADDITIONAL FADING OF THE SCATTERED SIGNAL OCCURS DUE TO TIME 
 2A BRIEF HISTORY Radar, the device which is used for detection and ranging of contacts, independent of time and weather conditions, was one of the most importantscientiﬁc discoveries and technological developments that emerged fromWWII. It’s development, like that of most great inventions was mothered bynecessity. Behind the development of radar lay more than a century of radiodevelopment. 
 The wavelength was 5 m. A proposal was submitted for further work but was not  accepted.  The first application or the pulse technique to the measurement of distance was in the  basic scientific investigation by Breit and Tuve in 1925 for measuring the height of the  ionosphere.4• 16 However, more than a decade was to elapse before the detection of aircraft by  pulse radar was demonstrated. 
 Onedegreeofmechanical rotation corresponds toaphasechangeofoneelectrical degree.Noadditional phase-shifting devicesarerequired. Anarrayofspiralelements makesasimplescanning antenna.Itis primarily wiefulinthoseapplications whereabroadband element isrequired andthepoweris nottoohigh.Theentireassembly, including thespiralradiators andfeednetworks, but possibly excluding therotaryjoint,canbemanufactured withprintedcircuittechniques. Helicalradiating elements havealsobeenusedinarraystoobtainphase shift~byrotation of theelements.62 Achangeinphaseinthewaveguide transmission maybeobtained bymechanically changing thedimensions oftheguide.2o,59Onesuchdevicethathasbeenappliedtopractical radarsistheEaglescanner, ordelta-ascanner. 
 Theelectromagnetic pathwithintheantenna structure isdesigned tocon­ vertthecircularmotionofthefeedtoalinearmotionoftheantenna beam.Insomedesignsthe beamsweepsacrossaplaneandthenreturnsbythesameroute.Inotherdesignsthescanis saw-tooth withthebeamsweeping acrosstheplaneofscanandthenstepping backalmost instantaneously toitsstarting point.Thesaw-tooth scanisgenerally preferred inradarapplica­ tions.Suchantennas wouldbeusedwhereasmallangular sectorneedstobecovered witha rapidscanrate.Theseantennas cancoverasectoroffrom10to20degreesormore,ata'rateof 10to20scanspersecondorgreater.Thisisarapidenoughratetopermitessentially contin­ uousobservation ofthetarget.Aradarwhichusessuchasector-scanning antenna totrackthe pathofairborne targetsissometimes calledatrack~wlJile-scan radar. Thedetailsoffeed-motion scanners maybefoundintheliterature.,·42.43 Manyofthese, suchastheRobinson, Foster,44.134 Lewis,andSchwarzchild, weredeveloped duringWorld WarII.Various typesoflenses,pillboxes, andtroughwaveguides havealsobeenusedfor mechanically scanning abeamoveranangularsector.Another mechanical scanner isacoaxial linewithradiating slotscutinitsside.1Theinnerconductor iscorrugated andeccentric with respecttotheouterconductor. Astheinnerconductor rotatesthewavelength intheline varies,causing thebeamtoscan. 
 Where the MFAR is phase steered, aperture fill and sidelobe steering effects  constrain usable aperture bandwidth similar to SAR limitations. The latter is because  the element phase angles required to point the main beam are not the same as those for  the outer sidelobes of the modulation used.81 Low bandwidth data links can use all the radar bandwidth to improve encryption  and signal-to-jam ratios. However, the data link on a weapon is traveling to the target,  which will inevitably attempt to protect itself. 
 More stringent acceptance criteria are applied in more active regions. Track File.  When a track is established in the computer, it is assigned a track num - ber. 
 Incases where the scanning isconfined to 90°orless, these variations ofthefirst method arethemost satisfactory ofall. Ifthe scan covers more than 90°, one ofthe diodes must be switched inpolarity from time totimefor example, byacam arrange- ment onthe scanner. Ifthe scan covers more than 180° both ofthem must besoswitched. 
 Wasylkiwskyj and W. K. Kahn, “Element pattern bounds in uniform phased arrays.” IEEE  Trans ., vol. 
 J. McLaughlin, “Multi-frequency radar  estimation of cloud and precipitation properties using an artificial neural network,” in 30th Int.  Conf. 
 (4.3} (Fig. 4.2c} and many pulses will be needed to extract the dopp\er  inrormation. The case illustrated in Fig. 
 4. Conclusions This paper presented a new method for SAR targets classiﬁcation on TerraSAR-X high-resolution images. To verify our method, we take several experiments to compare. 
 The asteroid has an average orbital speed of 25 km /s. However, asteroids orbiting closer to a sun will move faster than asteroids orbiting between Mars and Jupiter and beyond. The average orbital speed of a main-belt asteroid is 17.9 km /s, the orbital speed of Ceres. 
 FICULT TO CHANGE ONCE THE TARGET HAS BECOME A PRODUCTION ITEM   SHAPING IS BEST IMPLE 
 FEED SYSTEMS A  LENS ARRAY AND B  REFLECTARRAY . 
 S.: The Radechon. A Barrier Grid Storage Tube, RCA Rev., vol. 16, pp. 
 A small aircraft or missile decoy call be designed to have a radar cross section cotnparablc  with that of a large aircraft by fitting it wit11 radar signal enhancement devices such as corner  reflectors, Lutleburg reflectors, or active repeaters. The decoy could also be outfitted with a  srnall jammer to mimic jammers on the target aircraft in order to make the two appear  identical.  Decoys might be carried on board attacking bomber aircraft and launched outside the  normal radar detection ranges. 
 Figure 1. Position relationship of three ground tracks of PALSAR scenes and Poker Flat ISR. The red rectangle corresponds to the PALSAR scene of Group 1, while the green and the blue ones correspond to the measurement of Group 2 and Group 3, respectively. 
 These results reflect the less-than-optimum resolution, waveform precision, and orbit  inclination of those two altimeters. Geodetic resolution at the ocean’s surface can be  no finer than about 6 km (half a wavelength), a limit that is determined by the average  depth of the ocean. CryoSat: Ice Sheet Mission. 
 ( a) Traditional imaging processing; (b) imaging processing of proposed approach (mixed Euclidean norm); complex images of channels 1 and 2 (ﬁrst and second layers); interferometric phase images (third layer); ﬁnal 3-D imaging results (last layer). Randomly select 25% observed data from full data to generate the sparsity sampling data, and adopt traditional imaging approach and the proposed approach respectively to carry out InISAR imaging. The 3-D distribution of target scattering points is shown in Figure 12. 
 SITE QUASI 
 116. Schaerer, G. W.: Radar Observations or Insect Flight, chap. 
 ch17.indd   1 12/17/07   6:48:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 
   -ASSACHUSETTS )NSTITUTE OF 4ECHNOLOGY  ,INCOLN ,ABORATORY   !UGUST    HTTPWWWLLMITEDULLRASSPDOCUMENTSHTML  - ! 2ICHARD  h$IGITAL )1 v 3ECTION  IN  &UNDAMENTALS OF 2ADAR 3IGNAL 0ROCESSING     .EW 9ORK -C'RAW 
 TF/TA is an important aspect of stealth even when the  altitude is not all that low because lower altitudes provide some terrain obscuration  and many other competing targets with similar cross-sections.8 Terrain Height Estimation.  Some of the features of TF/TA are the required scan  pattern, the number of independent frequency looks required to obtain a valid estimate  of the height of a possibly scintillating object along the flight path, and the range cov - erage. Because terrain height is estimated through an elevation measurement, angle  accuracy is critical. 
 Binary images of the targets. ( a) Dihedral. ( b) Trihedral. 
 8.6 lower than that ofthe radar byafactor of20orso. Either the beam- width oftheantenna forreceiving replies from thebeacon ismade very broad orthis antenna ismade omnidirec bional. Microwave angular discrimination isstill provided bythe sharpness ofthe interrogating beam—again only forbeacons atranges beyond that forwhich side lobes begin tocause broadening ofthereply. 
 With sidelobe  jamming, the radar designer can reduce the jammer advantage by low sidelobe design  coupled with the use of sidelobe cancellation techniques. With main-beam noise jam - ming, the radar can maximize the received target energy by transmitting more average  power, dwelling longer on the target, or increasing the antenna gain. If the radar’s data  rate is fixed and a uniform angular search rate is dictated by mechanical or search  strategy, then the only option for the radar is to increase its average transmitter power. 
 DLE UP TO  K7 OF PEAK POWER HAVE BEEN BUILT 4HEY ARE AMENABLE TO WAVEGUIDE CONSTRUCTION AND ARE HEAVIER AND BULKIER THAN COMPARABLE DIODE DEVICES )N SUMMARY  DIODES AND NONRECIPROCAL FERRITE PHASE SHIFTERS ARE VIABLE COMPETITORS  !T , BAND AND LOWER  DIODE PHASE SHIFTERS ARE AN OBVIOUS CHOICE !T 3 BAND AND HIGHER  FERRITES SHOULD CONTINUE TO HOLD AN EDGE IN HIGHER 
 The haroverPrdenotesthatthereceived powerisaveraged overmanyindependent radarsweeps tosmooth thtsignalfluctuations. Thisequation assumes thatthevolume oftheantenna resolution celliscompletely filledwithuniform precipitation. Ifnot,acorrection mustbe madebyintroducing adimensionless beam-filling factortjJwhichisthefractionofthecross­ sectional areaofthebeamintercepted bytheregionofscattering particles.Itisdifficult to estimate thiscorrection. 
 TRACKING SYSTEMS USE HIGH SPEED SAMPLING CIRCUITRY TO TAKE THREE  TO FIVE SAMPLES IN THE VICINITY OF THE ECHO VIDEO PULSE 4HE AM PLITUDES OF THE SAMPLES  ON THE LEADING AND LAGGING HALVES OF THE PULSE ARE COMPARED FOR RANGE 
 wavelength apart which are usually supported by low-loss dielectric material. The construc­ tion of the parabolic reflector with thin parallel wires makes it polarization sensitive. That is, it  will completely reflect one sense of linear polarization and be transparent to the orthogonal  sense of polarization. 
 458 INTRODUCTION TO RADAR SYSTEMS  wavelengths, the geometrical horizon represents the approximate boundary between the re-  gions of propagation and no propagation. As the frequency decreases (increasing wavelength),  Fig. 12.7 indicates that more and more energy propagates beyond the geometrical horiron. 
 Fractional shifts of a  beamwidth can be achieved by changing the phase of a few (symmetric) pairs of phase  shifters in the array. In this way, a pseudo-continuous beam scan can be generated with  the required rates and rate changes.120 Because of pulse propagation delays from the target to the receiver, the pointing  angle of the receive beam qR must lag the actual pulse position. For an instantaneous  pulse position that generates a bistatic angle b /2, qR = qT − b. 
 TUDE 
 bandwidth RF amplifier, its dynamic range to wideband-noise interference may be severely restricted. When low-noise amplifiers (LNAs) are included in the antenna, prior to form- ing the receive beams, the sidelobe levels achieved are dependent upon the de- gree to which gain and phase characteristics are similar in all LNAs. Dynamic range has an exaggerated importance in such configurations because matching nonlinear characteristics is impractical. 
 FOURTHS OF A PULSE WIDTH  DEPENDING ON THE RELATIVE PHASE   DIFFERENCE BETWEEN THE TWO TARGETS -OREOVER  THIS RESULT CAN BE IMPROVED FURTHER BY PROCESSING MULTIPLE PULSES !UTOMATIC $ETECTION 3UMMARY  7HEN ONLY  TO  SAMPLES PULSES  ARE AVAIL 
 , 9Ê-/",9Ê"Ê-, 4HE ORIGINAL CONCEPT OF 3!2 WAS FIRST DESCRIBED BY #ARL 7ILEY OF 'OODYEAR IN   (E CALLED IT  DOPPLER BEAM SHARPENING $"3  ,ATER  THE DOPPLER BEAM SHARPENING MODE  OF 3!2 WAS INTRODUCED AS THE NAME FOR A VARIABLE SQUINT ANGLE MODE THAT PRODUCED A PARTIAL PLAN 
 WALL STRUCTURES ARE SHOWN IN &IGURE  AND ARE  KNOWN AS HOMOGENEOUS SINGLE LAYER  ! 
 This limitation is a function of the antenna pointing angle, the MTI filter  response, and the sidelobe pattern. If the sidelobes are relatively well distributed in  azimuth, a measure of performance can be obtained by averaging the power returned  by the sidelobes. The limiting improvement factor due to sidelobes is  IK G d G dsllimit4 sl=−∫ ∫4( ) ( )θ θ θ θππ  (3.10) where the lower integral is taken outside the main-beam region. 
 Zhang, X.; Shuai, P .; Huang, L. Phase tracking for pulsar navigation with Doppler frequency. Acta Astronaut. 
 878-885, November, 1968. (Also available in ref. I.)  8. 
 Sensors 2019 ,19, 490 (a)  (b) (c)  (d) Figure 4. Results of the four methods. ( a) GLRT result of BP; ( b) GLRT result of CS; ( c) GLRT result of debiased-CS; ( d) GLRT result of LS-CS-Residual. 
 (/2):/. 2!$!2   Óä°ÓÎ "UT THERE ARE DISADVANTAGES &IRST  EMISSION CONTROLS ARE ALMOST INVARIABLY A SERI 
 vol. 54, pp. 1964-1965, December, 1966. 
 TION WHILE PROVIDING THE PERFORMANCE NEEDED FOR OPERATIONAL APPLICATIONS 2ESEARCH RADARS ARE CONSIDERABLY MORE COMPLEX  SINCE CUTTING 
 Kroszcynski, J. J.: Pulsecompression by Means of Linear-Period Modulation, Proc. IEEE, vol. 
  D"  WHERE D" REFERS TO THE NUMBER OF DECIBELS BY WHICH THE AVERAGE  SIDELOBE LEVEL IS BELOW THE GAIN OF AN ISOTROPIC IDEAL  RADIATOR )N THEORY  EXTREMELY LOW SIDELOBES CAN BE ACHIEVED WITH APERTURE ILLUMINATION FUNCTIONS THAT ARE APPRO 
 Geosci. Remote Sens. 2015 ,53, 1016–1028. 
 Figure 14.1 shows an aircraft traveling with a constant velocity v along a straight path. Jts  radar antenna is mounted so as to radiate in the direction perpendicular to the direction of  motion. Such a radar is known as a sidelooking radar, or SLR. 
 An example is shown in Fig. 13.6.31 On the other hand, the totality of the NRL 4FR results appeared to show saturation for wind speeds above about 20 kn, but the high and low- to moderate- wind-speed data was collected at different times in different places under different conditions of sea-surface development, and discrepancies between the two data sets for common wind speeds have weakened the evidence for saturation.32 Other investigators deny that it is even possible to express wind dependence in the form of a power law, proposing the existence of a kind of threshold wind speed, below which clutter virtually van- ishes and above which the clutter level rises toward a saturation value.18 This is indicated by the curves in Fig. 13.7, where the straight lines correspond to vari- ous power laws. 
 RITHMS AS WELL AS OPTIMIZING THE FALSE 
    F   FR RV =   F    MAXIMUM PERIODMINIMUM PERIOD . 
 Another form of display is the A-scope,  shown in Fig. 1.3b, which plots target .amplitude (y axis) vs. range (x axis), for some fixed  direction. 
 received fromagivenelevation angle,thatcorrespond toonebeamwidth. AsstatedinSec.8.4. theechofromatargetisfrequency modulated whenilluminated bysuchafrequency-scanned beam.Pulse-compression filtering (similartochirp)canbeusedtoachieve arangeresolution equaltothereciprocal oftheone-way groupdelayalongthedispersive delayline(snakefeed) feedingthefrequency-scan array. 
 The antenna canbeoscillated once persecond. The beamwidths are0.7° inelevation and 2°inazi- muth. This last ismuch smaller than was atfirst thought feasible; it was argued that sosmall anazimuth beamwidth would render search for the target laborious. 
 Key attributes of satellite radar altimeters are summarized in  Table 18.4. Since 1973, oceanic height measurement accuracy has improved, due  primarily to more effective means of estimating and correcting systematic errors.  Performance also has benefited from innovative onboard hardware and algorithms  and more precise determination of the radial component of the orbit. 
 3. Night noise is much greater than day noise. 4. 
 VARYING FOR DETERMINISTIC  2& NULLING !RRAY CON 
 CUBIC MODELS HAVE BEEN PROPOSED BY .EWTON ET AL .UMERICAL RAY 
 J 62.Becker,J.E.,andR.E.Millett:ADouble-Slot RadarFenceforIncreased ClutterSuppression. IEEE Trans.,vol.AP-16.pp. 103-108, January, 1968. 
 3.12b) is increased by the doppler shift, while on the other  portion, it is decreased. If. for example, the target is approaching the radar, the beat frequency  f,(up) produced during the increasing, or up, portion of the FM cycle will be the differer~ce  between the beat frequency due to the rangef, and the doppler frequency shift fd [Eq. 
 NADO IS CLOSE ENOUGH TO THE RADAR TO BE RESOLVED BY THE BEAMWIDTH (OWEVER  IN CASES WHERE THE TORNADO FALLS ENTIRELY WITHIN THE BEAM  THE DOPPLER SPECTRUM WIDTH MAY BE USED TO ESTIMATE TORNADIC INTENSITY )N SOME CASES  BOTH A MESOCYCLONE AND ITS INCIPIENT TORNADO CAN BE DETECTED 7ILSON AND 2OESLI  SHOW AN EXCELLENT EARLY EXAMPLE OF A  TORNADO VORTEX SIGNATURE 463  EMBEDDED WITHIN A LARGER MESOCYCLONE -ICROBURSTS &UJITA AND #ARACENA FIRST IDENTIFIED THE MICROBURST PHENOMENON  AS THE CAUSE OF AN AIRLINER CRASH THAT TOOK PLACE IN  4HE MICROBURST AND ITS EFFECTS ON AN AIRCRAFT DURING TAKEOFF OR LANDING ARE DEPICTED IN &IGURE   4HE MICROBURST IS  SIMPLY A SMALL 
 34!4% 42!.3-)44%23   ££°££ 4HE DESIGN CHALLENGE FOR HIGH 
   "ECAUSE THIS MODEL IS A SAMPLED CONTINUOUS TIME ACCELERATION   IT IS PREFERRED WHEN UPDATE TIMES ARE VARIABLE BECAUSE THE TARGET DOES NOT MANEUVER MORE OR LESS WHEN THE UPDATE INTERVAL CHANGES 4HE EQUATIONS IN 4ABLE  CAN THEN BE USED TO CALCULATE THE FILTER PERFORMANCE IN  TERMS OF VARIANCE REDUCTION RATIOS AND TRACKING LAGS !DJUSTMENTS TO PARAMETERS OF  F TRACK  CAN BE MADE TO OBTAIN THE DESIRED NOISE AND LAG TRADEOFF 3ELECTION OF 4RACKING #OORDINATES  4HE +ALMAN FILTER ASSUMES LINEAR TARGET  MOTION AND A LINEAR RELATION BETWEEN THE RADAR DETECTIONS AND THE TARGET COORDINATES (OWEVER  RADARS MAKE DETECTIONS IN POLAR COORDINATES RANGE  ANGLE  DOPPLER   WHILE TARGET MOTION IS MOST LIKELY LINEAR IN #ARTESIAN COORDINATES  X  Y  Z  4HEREFORE  SOME  COMPROMISES MUST GENERALLY BE MADE IN SELECTING A COORDINATE SYSTEM FOR FILTERING 4ABLE  DESCRIBES THE DESIGN TRADEOFFS FOR DIFFERENT SELECTIONS 4HE POLAR +ALMAN FILTER IS RARELY USED BECAUSE OF THE PSEUDO 
 Before the end of March 1941 over 2000 transmitters and 1000 receivers had been delivered to the RAF. Unfortunately, although both ﬁrms were working to the same requirements, they produced slightly different technical solutions which required different indicator units, as will be discussed below. 2.2.1 LRASV development Building on experience on the Anson before the war, E G Bowen submitted proposals for long-range ASV (LRASV) in February 1940, based on the use of high gain Sterba or Yagi arrays looking sideways to the line of ﬂight [ 6]. 
 12, no. 3, p. 425, 1977. 
 Evolution of urban monitoring with radar interferometry in madrid city: Performance of ers-1/ers-2, envisat, cosmo-skymed, and sentinel-1 products. Int. J. 
 J. Curlander and R. McDonough, Synthetic Aperture Radar Systems and Signal Processing ,  New York: Wiley & Sons, 1991, pp. 
 BEAM 3CAN3!2 IN (( POLARIZA 
 Long, T.; Lu, Z.; Ding, Z.G.; Liu, L.S. A DBS Doppler centroid estimation algorithm based on entropy minimization. IEEE T rans. 
 The AFC can be applied to the  magnetron itself to keep it operating on its assigned frequency, within the limits of the  accuracy of the tuning mechanism. A magnetron can be mechanically changed in frequency over a 5 to 10% frequency  range and, in some cases, as much as 25%. Rapid mechanical tuning can be achieved  with a slotted disk suspended above the anode cavities. 
      
 71. E. F. 
 M. Salter, and W. K. 
 J.: A Yaw Stahili,cd S./\.R. Aerial. /11t<'r11t1tio11al C1111ft•n•11c<' R,I/JAR-77. 
 GARNET 9)' nTUNED OSCILLATORS BUT REQUIRES LINEARIZING CIRCUITS IF TUNING USES A VARACTOR &)'52%     (OW FINITE BEAMWIDTH CAUSES A NEAR 
 3, pp. 21-32,  1975.  35. 
 The persistence should then bedetermined entirely bythe requirements offreedom from flicker ontheone hand and freedom from blurring due tomotion onthe other.’ Ifasethas several indicators involving different scale factors, their persistence should theoretically begraded, fast screens being used onthe expanded displays where the picture changes rapidly and slower ones onthose displays covering large areas. Fortunately, itisusually thelatter onwhich thesignal-to-noise discernibility isofmost importance ,since the expanded displays are usually confined tonear-by regiens. Providing thescanning isnot too slow (for example, ifitisapproxi- mately one scan per second) certain types ofcascade screens will, if initially unexcited, display more than twice asmuch intensity after two scans asafter one, and soon,e~”en though theintensity may have decayed manyfold inthetime between scans. 
 Depending on the user-set mode, the data has to be converted to the correct refer - ence frame and displayed appropriately. CPA and TCPA are continually calculated   for all tracked targets, such that if limits preset by the user are breached, an alarm TABLE 22.4  Requirements for radar tracked target accuracy (95% levels)11 (Courtesy of IMO ) Time of Steady  State (minutes)Relative  Course  (degrees)Relative  Speed (kn) CPA (NM)TCPA  (minutes)True  Course  (degrees)True Speed  (kn) 1 min: trend † 11 1.5 or 10%  (whichever  is greater)1.0 − − − 3 min: motion ‡  3 0.8 or 1%  (whichever  is greater)0.3 0.5 5 0.5 or 1%  (whichever  is greater) † Trend is an early indication (after 1 minute) of the target’s speed and direction. ‡ Motion is the established assessment (after 3 minutes) of the tar get’s speed and direction. 
 Elevation Null Filling. Operation of a radar at a single frequency can result in a  lobed structure to the elevation pattern of an antenna due to the interference between  the direct signal (radar to target) and the surface-scattered signal (radar to earth’s sur - face to target). By a lobed structure, we mean that there will be reduced coverage at  some elevation angles (nulls) and increased signal strength at other angles (lobes). 
 DOPPLER PLANE  ARE SHOWN THE REGIONS IN WHICH SEVERAL TYPES OF CLUTTER AND HIGH ALTITUDE CHAFF ARE EXPECTED /N THE SAME DIAGRAM ARE SUPERIMPOSED THE EXPECTED TARGET TRAJECTORIES AND THE !& CONTOUR OF A  SAY  PULSE 
 For devices with very high power output, several transistor dice are always combined in parallel within a small her- metic ceramic package. In addition, some form of internal impedance pre- matching circuitry is often included in order to preserve the high intrinsic band- width of the semiconductor chip and to make the task of external impedance matching easier. The internal matching also increases the terminal impedances of the packaged device to a level where the component losses of the circuitry ex- ternal to the transistor become less critical. 
 Also for modes like TF/TA, a full set of off-angle diagnostics is performed, which  tests the integrity of the entire measurement, processing, and flight control chain often  enough to keep the probability of a failure-induced crash per flight below 10–6 in the  presence of jamming or component failures. In addition, there are initiated built-in tests at two levels: an operational readiness  test performed as part of mission initiation and a fault isolation test performed by the  maintenance crew in response to an operator deficiency report. Both tests take longer  and are more exhaustive. 
 (13.9), and therefore in larger values of a° as derived from measured values of <rc by Eq. (13.7). Most experimenters use the half-power beamwidth in Eq. 
 DEFINED DOPPLER SHIFT 4HE SAME TERM IS USED TO DESCRIBE THE ENTIRELY DIFFERENT MECHANISM WHERE CLUTTER SMEARING IN DOPPLER OCCURS AS A CONSEQUENCE OF RAPID VARIATIONS IN THE PROPAGATION PATH RATHER THAN IN THE MOTION OF THE SCATTERER -ETEORS AND THEIR TRAILS ARE THE MOST UBIQUITOUS SOURCE OF TRANSIENT ECHOES n  4HEY DISPLAY A REASONABLY WELL 
 B. Keller, “Geometrical theory of diffraction,” J. Opt. 
 Then, at the moment t, the distance from the antenna I(i∈TR1,TR2}) to the point Pis: Ri(t)=/radicalBig (R0+y)2+x2+( R0tanαi−z)2 =/radicalBig (R0+r0cos(θ0+ωt))2+( r0sin(θ0+ωt))2+( R0tanαi−z)2(1) where, αirefers to the pitch angle from the antenna ito the origin of target coordinate system. Assuming that the antenna transmits a step frequency wideband signal [ 26]: sit(t)=M−1 ∑ m=0rect/parenleftbiggt−tmp T/parenrightbigg exp[j2πfmt] (2) where: rect/parenleftbiggt−tmp T/parenrightbigg =/braceleftBigg 1, 0<t−tmp T<1; 0,t−tmp T<0andt−tmp T>1;(3) fm= f0+Δfis the frequency of the pulse centered at time tmpand for pulses spaced equally in frequency and time; tmp=( m+pM)T;Δfis the frequency difference for each step in the pulse burst; Tis the time interval between pulses (pulse repetition period of pulses in the burst); Mthe number of pulses in each burst; p=0,N−1-the index of emitted burst. The echo of the target received by antenna iafter the coherent demodulation is (to understand easily, rectangular coordinates are used): sir(t)=/dispiint Dgi(x,y)M−1 ∑ m=0rect/parenleftbiggt−tmp T/parenrightbigg exp[j2πfmRi(t,x,y) c]dxdy , (4) where, Drefers to the imaging scene area, (x,y)refers to the position coordinate of the target, and gi(x,y)indicates the backscatter coefﬁcient of the target at position (x,y)received by antenna i. 
 RANGE IMAG 
 D.V..andR.L.Olsen:Calculation ofRadiowave Allenuation DuetoRainatFrequencies up101000GHz,Communica/iolls Research Cel//re(Ollawa. Canada. CRCRep!.no.1299,Novem­ ber.1976. 
 97. Shrader, W. W.: MTI Radar, "Radar Handbook," M. 
 Clutter at millimeter wavelengths. In chap. 13 it was implied that knowledge of radar clutter  characteristics at microwaves was less than desired. 
 The antenna  is the device that allows the transmitted energy to be propagated into  space and then collects the echo energy on receive. It is almost always a directive  antenna, one that directs the radiated energy into a narrow beam to concentrate the  power as well as to allow the determination of the direction to the target. An antenna  that produces a narrow directive beam on transmit usually has a large area on receive  to allow the collection of weak echo signals from the target. 
            
 The two “convenience” cent rols aretheadjustments forrange-mark intensity and fordial-light brilliance. The operation ofthe AN-/APS-10 issosimple that anhour’s flight experience issufficient toqualify anavigator toadjust and usethe set. For ease inmaintenance, allunits ofthe sethave been made inde- pendently replaceable, with noneed ofadjustment forindividual units. 
 GENERATED PARTICLE BURSTS START TO ARRIVE AND ARE CHANNELED DOWN THE MAGNETIC FIELD LINES AT HIGH LATITUDES  CAUSING IONOSPHERIC HEAT 
 13•Polarization refers to the shape of the curve traced by the tip of the  electric field vector as a function  of time at a point in space. • Microwave systems are generally designed for linear or circular polarization.  • Two orthogonal linearly polarized an tennas can be used to generate  circular polarization.Wave Polarization 1 2 3 4 5 6LINEAR  POLARIZATION ELECTRIC FIELD   VECTOR AT AN  INSTANT IN TIME ORTHOGANAL TRANSMITTING ANTENNAS ELECTRIC FIELDS HORIZONTAL, HVERTICAL, V HORIZONTAL ANTENNA RECEIVES ONLY  HORIZONTALLY POLARIZED RADIATION12 3 4CIRCULAR  POLARIZATION. 
 1237. 34. He, K.; Zhang, X.; Ren, S.; Sun, J. 
 It has been said that the operating life of coaxial  tuhcs can be betweeti 5000 arid 10,000 hours, a five- to twenty-fold improvement compared to  corlventiorlal rnagnetr~ns.~~ Since most of the RF energy is stored in the TEol cavity rather  than in tlie resonator region, reliable broadband tuning of the magnetron may be accom-  plislied by a noncontacting plunger in the cavity. Both the pushingfigure (change in frequency  with a change in anode current) and the pulling figure (change in frequency with a change in  phase of the load) ale much less in the coaxial magnetron than in the conventional  configuration.  The external appearance of the coaxial magnetron, Fig. 
 39.Krason. II.,andG.Randig: Tcrrain Backscaltering Characteristics atLowGrazing Anglesfor.\'­ andS-Band. l'roc.IfEE.vol.54,pp.1964--1965, Decembcr. 
 NATE COEFFICIENTS IN THE 1 FILTER  AS SHOWN IN &IGURE C 4HE OPTIONAL NEGATION 
 RESPONDING RADAR SYSTEM DESIGN SOLUTIONS  GENERAL 34!0 PERFORMANCE COMPARISONS ARE DIFFICULT TO COME BY )N GENERAL  34!0 PROVIDES A ROBUST SOLUTION TO DEAL WITH CLUTTER AND JAMMING INTERFERENCE AND HELPS ALLEVIATE HARDWARE MISMATCH  EFFECTS WITHIN REA 
 NALS ARE ILLUSTRATED IN &IGURE  "ECAUSE  THE RELATIVE PHASE BETWEEN THE BACKGROUND SIGNAL AND THE TARGET SIGNAL IS UNKNOWN  TWO CURVES ARE SHOWN THEY CORRESPOND TO PERFECT IN 
 QUENCY DOMAIN WEIGHTING TYPES #URVE ! IS FOR UNIFORM WEIGHTING WHERE  7  F        &)'52%    #OMPARISON OF COMPRESSED 
 To generate the N filters simultaneously, each of the taps of the transversal filter of  Fig. 4.1 1 would have to be divided into N separate outputs with separate weights corrrspond-  Figure 4.23 MTI doppler filter  bank resulting from the processing  of N = 8 pulses with the weights of  Eq. (4.13), yielding the response of  Eq. 
 Direct niicrowavc  ;tr~;~logy of tlic optic;~l lcr~g (11) Zorlcld diclcctric Icns.  Orlc of the lirnit;~tio~ls of tile solid llotnogerieous dielectric lcns is its thick size and large  weight. Both the tllickness arid tile weight may be reduced considerably by stepping or zoning  the lcrls (Fig. 
 81. P. R. 
 Remote  Sens. , vol. 39 ,  pp. 
 6 PLANE DEFINE THE PEAK POWER PERFORMANCE ENVE 
 VIDING AUXILIARY FACILITIES  INCLUDING SOME OR ALL OF THE FOLLOWING I  #ONVENTIONAL ION 
 13.3) indicates that  the lo\r;c~ tllc I~cqr~c~~cy. tllc less tile sea cluttcr. I'llis applies at tlrc lower grazing ailgles and  with hori7or1tal polarization. 
 HUMPED DISTRIBUTION OF ERROR 2ANGE  -EASUREMENT  %RRORS  4HE  MAJOR  SOURCES  OF  TARGET  RANGE 
 We do not see the  beam, of course: what we see is the fluorescent effect  of the sharply focused electrons impinging on the  surface.  While we are, so to speak, at the screen end of the  tube let us just see of what it is composed. Radar  patterns are in blue, green, or similar colours; our needs  are rather different from those of television, where we  require as white a picture as possible. 
 if the target is stationary (zero doppler frequency), the amplitudes of the modulation-  frequeticy llarrnorlics are proportional to either J,(D) sin #, or J,(D) cos (boy where +, =  47th Ro/c = 4xR,/A. Therefore the amplitude depends on the range to the target in RF  wavelengths. The sirie or the cosine terms can take any value between + 1 and - 1, including  zero, for a change in range corresponding to one RF wavelength. 
 P. Rowe, watching on behalf of the Air Ministry,  saw radar reflections from an aircraft near Daventry in  1935. Roughly speaking, we can see how far away the  aircraft is from the transmitter, but, of course, to be of  any real use as a navigational aid radar must do far more. 
 SURFACE MISSION  THE MODE  STRUCTURE OF A MODERN FIGHTER AIRCRAFT AIR 
 14.8  Active Stabilizat ion  ............................................  14.8  Stabilization of Power Oscillato rs  .......................  14.11  14.5 Noise Measurement Technique  .............................. 
 Skolnik, Radar Handbook , 2nd Ed., New York: McGraw Hill, 1990.  2. M. 
 !n 
 DOPPLER CELL 4HIS PER 
 FREQUENCYv PULSES  OF WIDTH S 7ITHIN A PULSE GROUP  THE FREQUENCY OF A PULSE IS  $F GREATER THAN THAT OF  THE PREVIOUS PULSE  AND THE RADAR TRANSMITS  02& . GROUPS PER SECOND  WHERE  02&  IS THE PULSE REPETITION FREQUENCY 4HE WAVEFORM BANDWIDTH IS  .  
 The  crossed-field amplifier (CFA) is often cathode-pulsed, requiring a full-power modulator. Some  CF As are d-c operated, which means they can be turned on by the start of the RF pulse and  turned off by a short, low-energy pulse applied to a cutoff electrode. Some CF As can be turned  on and off by the start and stop of the RF pulse, thus requiring no modulator at.all. 
 TRACKING RADAR  9.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 is produced. The background noise from the airframe is also observed. The spikes  in the spectrum result from a fundamental modulation frequency related to the pro - peller rev/min and number of blades. 
 The one-dimensional hologramlike signals recorded along the horizon-  tal dinlension on the phase-Ilistory filtn provide focusing in the horizontal plane. A cylindrical  lens is used to focus the image in the vertical plane. The front focal-plane of the cylindrical lens  coincides with that of the phase-history film. 
 The reason behind this is that subsidence might occur over a short period of time and the rate of longtime monitoring would be relatively lower. Our longtime monitoring of land subsidence reﬂect a long term change of land subsidence relative to previous studies. The most severe ground settlement site of our study is located at Xinrong of HK, but in the study of Zhou et al. 
 HORIZON v )%%%  4RANS  VOL !%3n  NO   PP n  !PRIL   ' ! &ABRIZIO  ! &ARINA  AND - $ 4URLEY  h3PATIAL ADAPTIVE SUBSPACE DETECTION IN /4( RADAR v  )%%% 4RANS  VOL !%3n  NO   PP n  /CTOBER   ! &ARINA  ' ! &ABRIZIO  7 , -ELVIN  AND , 4IMMONERI  h-ULTICHANNEL ARRAY PROCESSING IN  RADAR 3TATE OF THE ART  HOT TOPICS AND WAY AHEAD v  0ROC 3ENSOR !RRAY AND -ULTICHANNEL 3IGNAL  0ROCESSING )%%% 7ORKSHOP INVITED PAPER   3ITGES  3PAIN  *ULY n    PP n  ' ! &ABRIZIO  ' * &RAZER  AND - $ 4URLEY  h34!0 FOR  #LUTTER AND )NTERFERENCE #ANCELLATION  IN A (& 2ADAR 3YSTEM v  )%%% )NT #ONF ON !COUSTICS  3PEECH  AND 3IGNAL 0ROCESSING     )#!330   4OULOUSE  &RANCE  -AY   $ + "ARTON  2ADAR 3YSTEM !NALYSIS AND -ODELING  .ORWOOD  -! !RTECH (OUSE  )NC  . 
 Wurman, S. Heckman, and D. Boccippio, “A bistatic multiple-doppler radar network,” Journal  of Applied Meterology , vol. 
 vol. AES-3. no. 
 An important decision relates to where the coordinate registration is implemented.  Some systems establish tracks in radar coordinates and then pass the tracks, including  multiple tracks from a single target, to the CR system, which must identify and recon - cile any multiple tracks as well as perform the registration. Alternatively, the problem  of target tracking can be integrated with the problem of determining the ionospheric  propagation paths. 
 H. M. Johanson. 
 Point A—bottom of dip—115 volts. Point B—optimum operating point The generator willregulate properly ‘117 ‘“lts. tothe left ofthe hump ortothe right ofthe dip. 
 When the display is connected  directly to the video output of the receiver, the information displayed is called raw video. This  is the " traditional " type of radar presentation. When the receiver video output is first  processed by an aut'omatic detector or automatic detection and tracking processor (ADT), the  output displayed is sometimes called sytlthetic video. 
 15) inwhich the scanner, rotating ateither 2or4rpm, carries two radar antennas and onebeacon antenna. One oftheradar antennas pro- vides long-range low-angle coverage; the other provides coverage athigh angles. Both regular video signals and MTI (Chap. 
 A. Turner (eds.):" Radar Scanners and Radomes," MlT Radia­ tion Laboratory Series, vol. 26, p. 
 For this plot, the UTC time is  1800, SSN = 50, Pav = 200 kW, GtGr = 50 dB, T = 1 s, and s = 20 dBsm. Figure 20.29  gives the corresponding night plot. The shape of these displays is quite similar to what would be seen with a diagnostic  oblique sounding; the levels would generally be greater because the resolution cell area  times the surface scattering coefficient is generally much larger than 20 dBsm. 
 A suffix letter ( A, B, C,…) follows the original designation for each modification  of the equipment where interchangeability has been maintained. The letter V in paren - theses added to the designation indicates variable systems (those whose functions  may be varied through the addition or deletion of sets, groups, units, or combinations  thereof). When the designation is followed by a dash, the letter T, and a number, the  equipment is designed for training. 
 38, pp. 1165-1171, October, 1950.  DETECTION OFRADAR SIGNALS INNOISE395 CFARiswidelyusedtopreventclutterandnoiseinterference fromsaturating thedisplay ofanordinary radarandpreventing targetsfrom-being obscured. 
 Flowchart of aspect entropy extraction at the target level. Scattering of the target at a certain angle is accomplished by the scattering of each pixel at this angle. Thus, the RCS curve of a target can be obtained by accumulation. 
 The larger,, is, the sharper will be the beam.  However, if,, is too large, the same difficulties as arise with the Dolph-Chebyshev pattern will  occur. The aperture illuminations for high values of n are peaked at the center and at the edge  of the aperture. 
 CHIRP  AND THE MINUS SIGN FOR A NEGATIVE ,&- SLOPE A  DOWN 
 Since Seasat was not yaw-steered, the fore and aft footprints  were misregistered due to Earth rotation, which reduced the useful swath at lower  latitudes to about 400 km. The value of Kp varied from 1% to 3% over the ocean under  moderate to high sea states, but degraded to 15% for lower wind speeds and to 50%  for very low backscatter from non-oceanic surfaces. The accuracies of wind speed  and direction over 4–16 m/s were ± 2 m/s and ± 20o, respectively. 
 REDUN 
 From Marcum [6] the achievable improvem ent, henceforth  identified as integration efficiency, is calculated.     . Radar System Engineeri ng Chapter 8 – Pulse Radar  59       The efficiency for n pulses is defined by:  € E(n)=(SN)1 n(SN)n (8.12)  (S/N) 1 = S/N for one pulse. 
 One way to overcome this problem in  a system that includes automatic tracking would be to use the track prediction gate to  inhibit updating of the clutter map with new (target) amplitudes. 2.16 SENSITIVITY-VELOCITY CONTROL (SVC) In the mid-1980s, several radar researchers had realized that signal processing algo - rithms to estimate the unambiguous radial velocity of a target using multiple PRF  dwells during the time of target were becoming practical. These radial velocity esti - mates could be used for improved false-alarm control against slow-moving targets  such as birds.30,47 When such radial velocity measurements are paired with corre - sponding cross section estimates a powerful discriminant for distinguishing between  slow-moving birds and low cross-section missiles becomes possible using the so- called sensitivity velocity control (SVC) algorithm.48 The SVC Concept. 
 Discrepancies in  either amplitude or phase will be evident from such data collected over a random dis - tributed scene. There is no need for a known point-target reference in the field of view.  The Stokes parameters that correspond to such measurements are sufficient to charac - terize the relative H/V phase of the transmitted field, as well as that of the receivers. 
 PLEMENT OF INCIDENCE ANGLE 4HE MEASUREMENTS WERE ALL AT LOW  DEPRESSION ANGLES  WITH  THIS TERM USED IN LIEU OF  GRAZING ANGLE BECAUSE IT CAN BE DEFINED IN TERMS OF ANTENNA  POINTING  WHEREAS GRAZING ANGLE ALSO DEPENDS ON LOCAL SLOPE  WHICH IS BOTH VARIABLE AND  IN GENERAL  UNKNOWN )MAGES TAKEN AT NEAR 
 pp.664673.June.1974. 21.Fenster. W.:TheApplication. 
 SCALE INSTABILITIES 3TRUCTURAL 6ARIABILITY  4HE DAY 
 Phase shifters suitable for steering phased arrays are  described in Section 13.9. Most of these phase shifters are digitally controlled and can  be set with an accuracy that is a function of the number of bits. A small number of bits  is desired for simplicity of phase-shift computation and operation, for minimal inser - tion loss in the case of diode phase shifters, and for minimal cost. 
 Any use is subject to the Terms of Use as given at the website. Meteorological Radar.  METEOROLOGICAL RADAR  19.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19  Prr cK D c Kr i iN = ==∑β πθφ τ π λ βπθφτ42 5 42 6 1 6 28 8| | | | λ λ β4 2 2rZ Z r=′ (19.10) This expression illustrates that for the distributed weather target the received power  is (1) a function only of b  ′ (a constant dependent upon all the radar system and physi - cal parameters), (2) directly proportional to the radar reflectivity factor Z, and most  significant, (3) inversely proportional to r2 (not r4 as in the case of point targets). The radar system parameters included in b in Eq. 
 HANDLING SYSTEM .3#!4  THE .!3! 3CATTEROMETER   PROVIDED TO *APAN AS PART OF THE !DVANCED %ARTH  /BSERVING 3ATELLITE !$%/3  PAYLOAD  WAS AN UPGRADED VERSION OF 3!33 .3#!4 USED SIX DUAL 
 The beam of an array antenna may be steered rapitfly in space without moving  large mechanical masses by properly varying the phase of the signals applied to each element. '  Consider an array of equally spaced elements. The spacing between adjacent elements is ti, and  the signals at each element are assumed of equal amplitude. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 track history (i.e., the last n detections). 
 TO 
 I3y en~ployi~ig some or all of the above techniques, tlle effect of the sidelobe noise jammer  can be sigr~ificantly reduced. Some of tile above techniques can also reduce the jamming that  enters via tile main beam. The effects of main-beam jamming can be further reduced by  eri~l~loying a narrow bearnwidtli to limit the region over which the jamming appears. 
 SIDELOBE RADARS  THE 4AYLOR ILLUMINATION   FOR THE SUM PATTERNS AND THE "AYLISS  ILLUMINATION FOR THE DIFFERENCE PATTERNS HAVE ALMOST BECOME AN INDUSTRY STANDARD  4HE 4AYLOR ILLUMINATION IS SOMEWHAT SIMILAR TO A COSINE SQUARED ON A PEDESTAL AND IS READILY IMPLEMENTED 4HE "AYLISS ILLUMINATION IS A DERIVATIVE FORM OF THE 4AYLOR ILLUMINATION AND IS ALSO READILY IMPLEMENTED )T SHOULD BE NOTED THAT IN MANY PHASED ARRAYS THE SIDELOBE PERFORMANCE FOR THE DIFFERENCE  PATTERN IS COMPARABLE TO THAT OF THE  SUM PATTERN &OR BOTH SUM AND  DIFFERENCE PATTERNS  THE SIDELOBE S ARE REFERENCED TO THE  PEAK OF THE SUM PATTERN 4HE BEAMWIDTH FACTOR PROVIDES THE BEAMWIDTH  IN DEGREES  OF AN APERTURE WITH LENGTH A &IGURE  GIVES THE APPROXIMATE LOSS IN GAIN AND THE BEAMWIDTH FACTOR FOR THE  4AYLOR ILLUMINATION AS THE SIDELOBES CHANGE &OR A MORE COMPREHENSIVE TREATMENT  SEE "ARTON AND 7ARD  4HE SIDELOBES PREDICTED BY 4ABLE  ARE FOR ANTENNAS THAT  HAVE PERFECT PHASE AND AMPLITUDE ACROSS THE APERTURE 4O ALLOW FOR ERRORS  APERTURE ILLUMINATIONS ARE OFTEN CHOSEN TO PROVIDE PEAK SIDELOBES BELOW THOSE REQUIRED &OR EXAMPLE  IF THE ANTENNA SPECIFICATION CALLS FOR  
 16.Bean.B.R..B.A.Cahoon. C.A.Samson. andG.D.Thayer:"AWorldAtlasorAtmospheric Radio Rerractivity." US.Dept.ofCommerce. 
 Record, vol. 8, pt. 4, pp. 
 14.12, as is obtained with fixed antennas generating fan beams.  554iNTRODUCTiON TORADAR SYSTEMS Receiver-16 1-<------- Db---------1 Figure14.12Geometry ofahistaticradar. manyseparated receivers areemployed withonetransmiuer, theradarsystemiscalled /1l1l/cj­ staCie.Someofthecharacteristics, capabilities, andlimitations ofthe bistatic radarwillbe described inthissectionandcompared withthemoreusualmonostatic radar. 
 6.3b). “Pip-matching” Displuys.-It isfrequently useful tocompare the strength ofthe radar echoes received from asingle target bymeans of antennas whose patterns differ indirection (see, forexample, Sec. 6.13). 
 Thus, the accelerations the system must handle need to be specified in order to select a suitable  Type I1 system. The tracking bandwidth of the servo system is defined as the frequency.where  its open-lodp filter transfer function is of unity gain. It represents the transition from closed  loop to open loop operation. 
 This page has been reformatted by Knovel to provide easier navigation. x     Contents   Digital Phase Detector  .......................................  3.38  3.11 Analog-to-Digital Converter  .................................... 
 Measurement of total radar instability can be conducted with the radar an- tenna searchlighting a stable point clutter reflector which produces an echo close to (but below) the dynamic-range limit of the receiver and doppler filter. Suitable clutter sources are difficult to find at many radar sites, and interruption of rota- tion of the antenna to conduct such a test may be unacceptable at others; in this case, a microwave delay line can be employed to feed a delayed sample of the transmitter pulse into the receiver. All sources of instability are included in this single measurement except for any contributors outside the delay-line loop. 
 The  period of the elliptical orbit was selected to be about three hours, so that in succession  each imaging pass overlapped and extended the surface imaged on previous passes. In the along-track direction, the antenna size had far-reaching consequences. The  theoretical (single-look) azimuth resolution available from the Magellan  antenna could  be about 1.6 meters (Section 18.2). 
 &IX PROCESSING SCHEME SUFFERS FROM THREE LIMITATIONS 4HE FIRST IS RELATED TO THE DETECTION LOSS EXPERIENCED WHEN THE TARGET DOES NOT COMPETE WITH THE JAMMER 4HE SECOND DISADVANTAGE REFERS TO THE MASKING EFFECT OF A WEAK TARGET SIGNAL SUFFICIENTLY CLOSE IN RANGE COMPARED WITH THE SPATIAL EXTEN 
 FORE MORE PRODUCTIVE TESTING  BUT UNLESS A VERY LARGE FACILITY IS AVAILABLE  MAXIMUM TARGET SIZES ARE LIMITED TO ONE OR TWO DOZEN FEET "ECAUSE OF THEIR PROXIMITY  THE WALLS  FLOOR  AND CEILING MUST BE COVERED WITH HIGH 
 Harvey, G. G.: Report of Conference on Rapid Scanning, MIT Radiation Lab. Repc. 
 Ê 
 After being multiplied by the deramping function, the data are as follows. s(ta)=rect/parenleftbiggta Ts/parenrightbigg exp/parenleftBig j2πfdcta+jπedrt2 a+jπe3rdt3 a/parenrightBig , (3) where edrand e3rdrepresent the errors of the Doppler rate and the derivative of the Doppler rate, respectively. Then, the data are divided into three equal long sub-segments as (4). 
 ~ -30  It:  "'  "' ~ -40 u  -50  -60 10 RADAR CLUTIER 493  NJ residential/'~'- ~:~'.:'-nix  x x~~ ~-ll~:-,,~Rurol  Phoenix -x,~Marsh  'I _x ,.,,..,-_ -----1<...._ 'Mis  NJ rurolx ... x--x~---v-~ ·-. Desert ----~ X . 
 In  contrast, the choice of receiving antenna element has traditionally been based on the I. M ICROWA VE  RADAR II. HF SKYWA VE  RADAR Frequency constraints Can be serious  because of the need for  wideband radar systems  and by competition  for the microwave  frequency spectrum by  communications and other  electromagnetic services•  Bounded above by the statistical  availability of skywave propagation  to ranges of interest •  Bounded below by spectrum  availability, antenna size, and the  rapid fall-off in target RCS •  Must not interfere with other users  in the crowded HF spectrum, thus  limiting choice of frequency and  bandwidth •  Must adapt continually to the  changing ionosphere so as to  maintain illumination of current  target region Noise floor dominated by Internal receiver noise  (thermal, etc.)Sources (atmospheric, galactic,  anthropogenic, etc.) Siting constraints •  Unobstructed, elevated  sites preferred•  Receive array site must be EM  quiet, generally rural, to avoid  city and industrial noise at HF  frequencies •  Huge arrays require flat, open  spaces to minimize topographic  effects on beam patterns •  If a bistatic or two-site quasi- monostatic design is adopted, it  needs two sites with adequate  separation (~100 km) and the  correct geographical relationship  relative to the coverage arc •  Location on the Earth must be such  that auroral and equatorial spread  doppler echoes don’t mask targetsTABLE 20.1  Key Differences Between Microwave Radar and HF Skywave Radar   (The parameter values quoted here are intended to be broadly representative, rather   than an attempt to span all known systems.) ( Continued ) ch20.indd   10 12/20/07   1:15:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 TION   THE 2& PROCESSING BANDWIDTH IS SIGNIFICANTLY LARGER THAN THE )& BANDWIDTH  #ONSEQUENTLY  THE TERM  INSTANTANEOUS BANDWIDTH CAN BE CONFUSING #ONFUSION CAN BE  AVOIDED BY USING THE TERMS  2& WAVEFORM BANDWIDTH  ,/ LINEAR &- CHIRP  BANDWIDTH    AND )& PROCESSING BANDWIDTH 4HE RELATIONSHIP BETWEEN 2&  ,/  AND )& BANDWIDTHS  USED IN STRETCH PROCESSING IS EXPLAINED IN MORE DETAIL LATER 4HE TUNING RANGE IS THE FREQUENCY BAND OVER WHICH THE COMPONENT MAY OPERATE  WITHOUT DEGRADING THE SPECIFIED PERFORMANCE 4UNING IS TYPICALLY ACCOMPLISHED BY ADJUSTING THE LOCAL OSCILLATOR FREQUENCY AND ADJUSTING THE 2& FILTERING CHARACTERIS 
 Selecting the preferred solution should be  based on a well-defined criterion. ● Detailed description of the selected approach .  This is in terms of the characteristics of the radar and the type of subsystems to   be employed. 
 The effect of increasing wind speed is simply to move the low-frequency cutoff to lower frequencies along the high-frequency /-minus-5 asymptote. (It should be noted that most of the oceanographers' spectra are based on measure- ments at relatively low frequencies and so cannot be taken seriously at frequen- cies above about 2 Hz. Nevertheless, these spectral forms are often used up to 20 Hz or greater in predicting radar clutter under the Bragg hypothesis.) Converting this frequency spectrum into an isotropic wavenumber spectrum through Eq. 
 It was recommended for ASV Mk. III that the discriminator should be employed if the sea return extended beyond4.5 nmi. The report also reminded operators that careful control of gain and contrast would still be required when homing on a target. 
 ING VECTOR OR ELSE CANCELLATION OF THE WANTED SIGNAL WILL OCCUR Óä°££Ê -  Ê*," 
 C. Shelton,  A. B. 
 Shrader and Vilhelm Gregers-Hansen2.1 2.1  Preface / 2.1 2.2  Introduction to MTI Radar / 2.2 2.3  Clutter Filter Response to Moving Targets / 2.9 2.4  Clutter Characteristics / 2.10 2.5  Definitions / 2.19 2.6  Improvement Factor Calculations / 2.23 2.7  Optimum Design of Clutter Filters / 2.25 2.8  MTI Clutter Filter Design / 2.33 2.9  MTI Filter Design for Weather Radars / 2.46 2.10  Clutter Filter Bank Design / 2.52 2.11  Performance Degradation Caused by Receiver L imiting / 2.59 2.12  Radar System Stab ility Requirements / 2.65 2.13  Dynamic Range and A/D Conversion Considerations / 2.78 2.14  Adaptive MTI / 2.80 2.15  Radar Clutter Maps / 2.83. 2.16  Sensitivity-velocity Control (SVC) / 2.87 2.17  Considerations Applicable to MTI Radar Systems / 2.91.     vi Chapter 3 Airborne MTI James K. 
 Vivekanandan, and E. Brandes, “A method for estimating rain rate and drop size  distribution from polarimetric radar measurements,” IEEE Trans. Geosci. 
 That region is defined for a smooth earth as the common-coverage area Ac. From Eqs. (25.9), (25.10), and (25.12), when ht = O and L > rR + rT = 130 (Vh^ + V/^), Ac for ground clutter is zero, and no sidelobe (or main-lobe) clutter enters the receive antenna. 
 3.9 IFLIMITERS Applications. When signals are received that saturate some stage of the radar receiver which is not expressly designed to cope with such a situation, the distortions of operating conditions can persist for some time after the signal disappears. Video stages are most vulnerable and take longer to recover than IF stages; so it is customary to include a limiter in the last IF stage, designed to quickly regain normal operating conditions immediately following the disappearance of a limiting signal. 
 Gould: Description of an Experimental Bistatic Radar Sys- tem, IEE Int. Radar Conf. Publ. 
     PP n    " ! - "OUMAN AND ( 7 * VAN+ASTEREN   'ROUND 
 WAVE PATH BETWEEN TARGET AND RADAR  NOT THE DISTANCE AS MEASURED ALONG THE %ARTHS  SURFACE 4HE IONOSPHERIC REFLECTION HEIGHT NEEDS TO BE USED TO CONVERT THIS SLANT RANGE TO GREAT 
 The required accuracy for the TACCAR control loop can be  relaxed if the MTI filter is an adaptive filter, such as with space-time adaptive process - ing (discussed later in this chapter). This is because the adaptive filter will adjust to the  received signals and optimize clutter cancellation. Without adaptive adjustment, Figure 3.9 shows the improvement factor for single-  and double-delay cancelers as a function of the ratio of the notch-offset error to the  pulse repetition frequency (PRF) for different clutter spectral widths. 
 CENTRIC  USING AND PROVIDING DATA TO A  COMMUNICATIONS NETWORK AND WHERE SUITABLY EQUIPPED  HAS ITS OWN )NTERNET PROTOCOL )0  ADDRESS -ULTIFUNCTIONALITY IS NOT DEPENDENT ON ANTENNA TYPE )N FACT  THE MECHANICALLY  SCANNED !.!0' 
   
 (a) (b) FIG. 12.12 CW-scatterometer-system block diagram, (a) Separate transmitter and receiver calibration, (b} Calibration of the ratio of received to transmitted power. The CW scatterometer is shown in block form in Fig. 
 STATES  AND THEREFORE  SOME MARKERS ARE SUPPLEMENTED BY RADAR BEACONS CALLED RACONSSEE 3ECTION   2ACONS ARE RELATIVELY EXPENSIVE AND NEED MAINTENANCE IN OFTEN DIFFICULT TO ACCESS LOCATIONS  SO THEIR USE IS RESTRICTED 7HILE '.33  ENHANCED BY THE GROWING USE OF ELECTRONIC CHARTS  HAS HELPED GREATLY IN INFORMING MARINERS OF THE PRECISE POSITION OF THEIR VESSEL  RADAR IS STILL USED AS AN IMPORTANT SECONDARY SOURCE OF POSITION 2ELIANCE ON '.33 ALONE HAS BEEN AT THE ROOT OF MANY MARINE ACCIDENTS 4HE MAIN USE OF MARINE RADAR IS TO ASSIST COLLISION AVOIDANCE  6ISUAL OBSERVA 
 Experimental measurements, however, showthatZisrelatedtotherainfallrateI'by (13.20) whereaandhareempirically determined constants. Withthisrelationship thereceiveJ echo powercanberelatedtorainfallrate.Anumberofexperimenters haveattempted todetermine theconstants inEq.(13.20),butconsiderable variability existsamongthereporteJ results.7o Partofthisisprobably duetothedifficulty inobtaining quantitative measurements andthe variability ofrain with timeandfromonelocation toanother. OneformofEq.(13.20)thathas beenwidelyaccepted is Z=2001'1.6 (13.21) (13.22)whereZisinmm6/m3andrisinmm/h.Thishasbeensaidtoapplytostratiform rain.For orographic rainZ=311'1.71andforthunderstorm rainZ=486':1.37. 
 T. Lo, “On the Beam Deviation Factor of a Parabolic Reflector,” IRE Trans ., vol. AP-8,  pp. 
 This gives acontinuous indication ofthepower output and. 720 RADAR RELAY [SEC.17.12 provides ameans ofmeasuring thestanding-wave ratio ontheline. The bidirectional coupler consists ofashort section ofline inwhich ismounted adirectional pickup loop. 
 11. Rabiner, L. R., and C. 
 At 30" grazing angle, for exarnple, the variation  of ao as a function of the water content of the snow is in the range -0.3 to -0.6 dBlO.1 glcmZ  over the frequency range from L to C bands. Other measurements indicate that the presence of  490INTRODUCTION TORADAR SYSTEMS Examples oflandclutter.Thereexistmanymeasurements oflandclutter,buttherehasbeen relatively littlecodified andcondensed information. References 9,35,and36summarize much ofwhathasbeenpublished regarding landclutter.Notonlyistherealackofpublished data forthevarious typesoflandclutter,butthereisnotalwaysagreement amongsimilardata takenbydifferent investigators. 
 Due to the narrow ribbon characteristics of our observed object, the multi-look ratio along range and azimuth directions was set as 1:1 to ensure the original resolution of the test highway. The thresholds for the temporal-spatial baseline of the interferometric combination were empirically set to 130 m and 300 days, respectively. SARScape 5.2 and Envi 5.3 were used in our experiment to generate a total of 57 small baseline interferometric pairs. 
 18FUNCTIONS OF COMPONENTS Power Supply In ﬁgure 1.13 the power supply is represented as a single block. Functionally,thisblockisrepresentative.However,itisunlikelythatanyonesupply source could meet all the power requirements of a radar set. Thedistribution of the physical components of a system may be such as to makeit impractical to group the power-supply circuits into a single physical unit.Different supplies are needed to meet the varying requirements of a systemand must be designed accordingly. 
 BAND PATCH ARRAY ON 3EASAT OR THE SLOT 
 where N is the number of scatterers per unit volume and (J1 is the backscattering cross section of the ith scatterer. In general, the meteorological scatterers can take on a variety of forms, which include water droplets, ice crystals, hail, snow, and mixtures of the above. Mie13 developed a general theory for the energy backscattered by a plane wave impinging on spherical drops. 
 8.19 is not taken. To maintain the same CFAR loss as for linear video, the number of reference cell Aflog for the log CFAR should equal Mlog = 1.65 Mlin - 0.65 (8.21) where Mj1n is the number of reference cells for linear video. The effect of target suppression with log video is discussed later in this section (Table 8.2). 
 The precision ofthe circuit islargely determined byLand C,which should betemperature- compensated and well shielded. Since RIhas some effect onfrequency, itshould beofareasonably stable type. Frequent yadjustment isbest made byslug-tuning the coil L.Once aligned, awell-designed unit should maintain itscalibration tobetter than 1percent. 
 Inonealtimeter,3o themodulation frequency wasvariedataIO-Hz rate,causingthephaseshiftofthebeatsignaltovarycyclically withtime.Theindicating systemwasdesigned sothatitdidnotrespondtothelO-Hzmodulation directly,butitcaused thefixederrortobeaveraged. Normalfluctuations inaircraftaltitudedueto uneven terrain, wavesonthewater,orturbulent aircanalsoaverageoutthefixederrorprovided thetime constant oftheindicating deviceislargecompared withthetimebetween fluctuations. Over smoothterrain,suchasanairportrunway,thefixederrormightnotbeaveraged out.Notethat evenifthefixederrorwercnotprcscnt,theaccuracy withwhichtheheightcanbemeasured willdependonthesignal-to-noise ratio,asdiscussed inSec.11.3,andcanbecomparable to thefixederrorasgivenbyEq.(3.14). 
 ................................ ................................ ................................ 
 PERSIVE  WHICH WOULD RESULT IN THE SAME IMPULSE RESPONSE AS THAT SHOWN IN &IGURE  A  &OR A GIVEN CRYSTAL LENGTH AND MATERIAL  THE WAVEFORM DURATION FOR THE APPROACHES IN &IGURE A AND &IGURE B WOULD BE THE SAME AND IS LIMITED TO THE TIME THAT IT TAKES  AN ACOUSTIC WAVE TO TRAVERSE THE CRYSTAL LENGTH &IGURE  C SHOWS A REFLECTION 
 TRACKING RADAR189 73.Simpson. II.R.:Performance Measures andOptimization Condition foraThird-Order Sampled­ DataTracker. IEEETrails..vol.AC-X.pp.IX2IRJ.April.1963. 
 In the MTD used for ASR application K is 7:8, which effectively averages the last eight scans. The main utility of clutter maps is with fixed-frequency land-based radars. While clutter maps can be used with frequency-agile radars and on moving platforms, they are not nearly as effective in these environments. 
 D.: The Electromagnetic Interference Environment: Man-Made Noise, pt. 1: Estima  lion of Business, Residential and Rural Areas, Office of Telecomm11nicatio11s, U.S. Departmet1t vf  Commerce, 1974. 
 Shaping. Shaping is the result of judiciously orienting target surfaces and  edges in a way that minimizes their contributions to the total radar echo. This often  means selecting airframe shapes and naval hull profiles that initially outrage air - frame designers and naval architects. 
 (1 1.37) is recognized as an inverse Fourier  transform  This is analogous to the inverse Fourier transform relating the frequency spectrum S(/) and  the time waveform s(t), or  * 00  As the antenna scans at a uniform angular rate w,, the received signal voltage from a fixed  point source will be proportional to G,(0) = Gv(w,t) and may be considered a time waveform.  If811 [in Eq. (1 1.38)] is identified with t in Eq. 
 12.7 indicates that more and more energy propagates beyond the geometrical horizon.  However, the field strength at, and just within, the geometrical horizon decreases with decreas­ ing frequency.  It is concluded that if low-altitude radar coverage is desired beyond the geometrical  horizon in the diffraction region, the frequency should be as low as possible. 
 CESSFUL CAN EXPECT A HOSTILE ADVERSARY TO EMPLOY COUNTERMEASURES TO REDUCE ITS EFFEC 
 PATH FROM THE EXPLOITED TRANSMITTER  ALSO CALLED  DIRECT 
 100-109, September 1945. 5. The SCR-584 Radar, Electronics, vol. 
 228-9,  March, 1973.  100. tlering, K. 
 ERATION )F THE DESIRED REJECTION RATE FOR THE CORRECT TRACK IS  02  ONE CAN OBTAIN THIS BY  SETTING 4,   02 4HE THRESHOLD  4( IS SET EQUAL TO  0FA  DEFINED AS THE PROBABILITY OF FALSELY  ASSOCIATING A RADAR TRACK WITH A $& SIGNAL WHEN THE $& SIGNAL DOES NOT BELONG WITH THE RADAR TRACK 4HE THRESHOLD  4 ( IS A FUNCTION OF THE AZIMUTH DIFFERENCE  L BETWEEN THE  TRUE $&  POSITION AND THE RADAR TRACK UNDER CONSIDERATION 4HE THRESHOLD  4( WAS FOUND  FOR L   R AND  L   R BY SIMULATION TECHNIQUES  AND THE RESULTS FOR  0FA    ARE  SHOWN IN &IGURE  "ETWEEN THE HIGH AND LOW THRESHOLDS  THERE IS A TENTATIVE REGION 4HE MIDDLE THRESHOLD DIVIDES THE hTENTATIVEv REGION INTO A TENTATIVELY CORRELATED REGION AND A TENTATIVELY UNCORRELATED REGION 4HE RATIONALE IN SETTING THE THRESHOLD IS TO SET THE TWO ASSOCIATED ERROR PROBABILITIES EQUAL FOR A PARTICULAR SEPARATION 4HE THRESHOLD  4 -  WAS FOUND BY USING SIMULATION TECHNIQUES AND IS ALSO SHOWN IN &IGURE  4HE PROBABILITY MARGIN  2 ENSURES THE SELECTION OF THE PROPER $& RADAR ASSOCIATION  AVOIDING RAPIDLY CHANGING DECISIONS  WHEN THERE ARE TWO OR MORE RADAR TRACKS CLOSE TO ONE ANOTHER 4HE CORRECT SELECTION IS REACHED BY POSTPONING A DECISION UNTIL THE TWO HIGHEST ASSOCIATION PROBABILITIES DIFFER BY  2 4HE VALUE FOR  2 IS FOUND BY SPECIFYING A  PROBABILITY OF AN ASSOCIATION ERROR  0 E ACCORDING TO  0E   0 0MAX q 0NEXT   2   WHERE  0MAX CORRESPONDS TO AN INCORRECT ASSOCIATION AND  0NEXT CORRESPONDS TO THE CORRECT  ASSOCIATION 4HE PROBABILITY MARGIN  2 IS A FUNCTION OF  0E AND THE SEPARATION  L OF THE  RADAR TRACKS 4HE PROBABILITY MARGIN  2 WAS FOUND FOR  L   R  R  AND  R BY  USING SIMULATION TECHNIQUES  AND THE RESULTS FOR  0E    ARE SHOWN IN &IGURE   &)'52%   (IGH THRESHOLD SOLID LINES  AND MIDDLE THRESHOLD DASHED LINES   VERSUS NUMBER OF SAMPLES FOR TWO DIFFERENT SEPARATIONS  AFTER '6 4RUNK AND *$  7ILSON Ú )%%%  . Ç°xÓ  2!$!2 (!.$"//+  "ECAUSE THE CURVES CROSS ONE ANOTHER  ONE CAN ENSURE THAT  0E a  FOR ANY  L BY SETTING  2 EQUAL TO THE MAXIMUM VALUE OF ANY CURVE FOR EACH VALUE OF N 4HE ALGORITHM WAS EVALUATED BY USING SIMULATIONS AND RECORDED DATA 7HEN THE  RADAR TRACKS ARE SEPARATED BY SEVERAL STANDARD DEVIATIONS OF THE DETECTION ERROR  COR 
 Daley et al.25) ch15.indd   9 12/15/07   6:16:58 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter. 
 Each plotter isconnected by telephone with ateller who iswatching aB-scope inthereporting shelter. Auxiliary boards tothe right and left ofthe main plotting board give pertinent information onsuch things asthe heights reported (by an auxiliary radar height-finder) forvarious tracks, weather and winds aloft, radio-frequency channels inuse forcommunications and fordirection- findng, and the ready status ofaircraft atvarious fields. The deputy controllers, each of\vhom ischarged with giving instruc- tions toacertain formation asdirected bythechief controller, depend on theplotting board fortheir general picture oftheairsituation, and work directly from their PPI scopes todetermine theinstructions tobegiven. 
 18.  pp. 39-42, November, 1975. 
 LIKE  WHEREIN THE SYSTEM DYNAMIC RANGE SHOULD BE LIMITED TO PREVENT THE INSTABILITY RESIDUE FROM EXCEEDING THE SYSTEM NOISE LEVEL &)'52%  0OLAR REPRESENTATION OF A LINEAR CLUTTER SEQUENCE  FOR  HITS PER BEAMWIDTH  AFTER 4 - (ALL AND 7 7 3HRADER  Ú )%%%                    
 The rms quantization noise is Q/ 12, and signal-   to-quantization-noise ratio (SQNR) of an ideal A/D converter is given by  SQNR (dB) = 6.02 N + 1.76 (6.37) Practical A/D converters have additional sampling errors other than quantization,  including thermal noise and aperture jitter. Provided that these additional errors can  be characterized as white, they can be combined with the quantization noise with a  resulting SNR less than the theoretical SNR of the ideal converter. Because various  A/D converter error mechanisms are dependent on input signal level and frequency,  it is important to characterize devices over the full range of input conditions to be  expected. 
 Another, which seems obvious but presents con- siderable tethnical difficulty, isthat ofdirect optical projection ofan enlarged real image ofthedisplay onanappropriate screen. The light intensity from apersistent cathode-ray-tube screen ofthe usual type istoolow forsatisfactory enlarged projection. Several alter- native methods ofaccomplishing the same result have been used or proposed, including: 1.Splitting the cascade screen (Sec. 
 In addition, the corresponding current ﬁeld reanalysis data was obtained from the Global Ocean Data Assimilation System (GODAS) with a spatial resolution of (1/3)◦×1◦. A ﬁve-day average of the current ﬁeld data from 25 April 2005 to 29 April 2005 was considered. According to the above data, the wind speed near the eddy area is 5.21 m/s, the wind direction is 223.6◦, and the current velocity is 0.26 m/s. 
 (14.1 1h) is also reduced by a factor of 2.  Wlieri a sytitlietic-aperture radar images the ground from an elevated platform, the unam-  biguous range can correspond to tlie distance between the forward edge and the far edge of the  region to be mapped. This requires that the elevation beamwidth be tailored to illuminate only  the swath S,, that is to be imaged by the radar. 
 MERIT FOR CAPABILITY OF THE SEMICONDUCTOR AND THE UNIT &%4 IS THE POWER OUTPUT DENSITY  AND THIS IS GIVEN IN UNITS OF WATTSMM OF TOTAL &%4 GATE WIDTH OR GATE PERIPHERY &OR OPERATING VOLTAGES OF n VOLTS  A NORMALIZED POWER OUTPUT DENSITY OF n 7MM SHOULD BE EXPECTED FOR MORE ADVANCED 'A!S 0(%-4 STRUCTURES OPER 
 SCAN ANTENNAS v  !NTENNA %NGINEERING (ANDBOOK  #HAP   2 # *OHNSON  AND ( *ASIK EDS   ND %D  .EW 9ORK -C'RAW 
 CENTER DIS 
 Rept. 248, October 30,  1952. 75. 
 G. V oronovich, Wave Scattering from Rough Surfaces . New York: Springer-Verlag, 1994. 
 By employing theprinciple ofmultipacting, arecovery timeasshortas5nsispossible.44•51A multipactdf isavacuum tubewhichcontains surfaces capable ofahighyieldofsecondary emission uponimpactbyanelectron. Th'esecondary emission surfaces arebiasedwithad-c potential. Thepresence ofRFenergycauseselectrons tomakemultiple impactstogenerate by secondary emission alargeelectron cloud.Theelectron cloudmovesinphasewiththeoscilla­ tionoftheapplied RFelectricfieldtoabsorbenergyfromtheRFfield.TheRFpoweris dissipated thermally atthesecondary emission surfaces. 
 TO 
 MINUTE TIME LAPSE OF !.&0. 
 344INTRODUCTION TORADAR SYSTEMS reference signalsareneededtoproperly extracttargctinformatioll. Specific applicatiolls such asMTIradar,tracking radar,orradarsdesigned.to minimize dutterplacespecialdelllalHls on thereceiver. Receivers thatmustoperate withatransmitter whosefrequency candriftneed somemeansofautomatic frequency control (AFC).Radarsthatencounter hostilecounter­ measures needreceivers thatcanminimize theeffectsofsuchinterference. 
 8.11 Comparison of various detectors in log-normal (cr = 6 dB) in- terference (N = 3; Pfa = 10~6). (Copyright 1975, IEEE; after Ref. 79.) density. 
 Vgand Vsatrepresent the ground velocity and the platform velocity, respectively. θi0is the ionospheric incident angle of beam center in zeros Doppler plane. Due to 184. 
 ATED THROUGH MIXER CHARACTERIZATION MEASUREMENTS TO PREDICT MIXER SPURIOUS LEVELS !DVANCES IN MIXER TECHNOLOGY HAVE RESULTED IN A WIDE VARIETY OF COMMERCIALLY  AVAILABLE DEVICES EMPLOYING BALANCED  DOUBLE BALANCED  AND DOUBLE 
 For example, if the magnification factor is 10 and the  ESA feed array is scanned 30°, the reflector beam will scan approximately 3°. ch12.indd   23 12/17/07   2:31:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 ELECTRONIC COUNTER-COUNTERMEASURES  24.496x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 formation in order to reduce the speckle noise. Traditional digital multilook processing  consists of an incoherent addition of independent images (looks) of the same scene.  The looks can be obtained by partitioning the available signal bandwidth (range and/ or azimuth) and processing each look independently. 
 Ithas been necessary to. SEC, 9.17] STABILIZATION OFTHEBEAM 305 devise means ofcompensating forthe angular motions ofsuch vehicles, and this mactice isknown asstabilization.’ The techniaue falls into two broad divisions, depending onwhether the beam ofradiation is stabilized, orthe data displayed onthe indicator arestabilized orcor- rected forthedistortions caused byatilting vehicle. Ingeneral there isnochoice between the two types ofstabilization. 
 C. Cook, “Radar transparencies of mine and tunnel rocks,” Geophys ., vol. 40, pp. 
 CUITRY MAKE THE PHASE 
 The nature of the  surface roughness can be inferred from the radar echo, as can the dielectric properties of the  scattering surface. The former has been applied to the measurement of sea state (iron1 satel-  lites), and the latter was used in early radar astronomy to probe the nature of the moon's  surface.  11.3 THEORETICAL ACCURACY OF RADAR MEASUREMENTS  The ability of a radar to detect the presence of an echo signal is fundamentally limited by noise. 
 thefrequency variation from being animpos- sibly large fraction ofthemean trequency. Ontheother hand there isno gain invery high frequencies and there may besome loss inintensity over such terrain asforests. These considerations, plus aconsideration ofthe tubes available, ledtothe choice ofamean frequency of440 Me/see, which can beobtained from acorn tubes; thefrequency modu- lation isaccomplished mechanically. 
 CORRELATES THE RECEIVED AND TRANSMITTED SIGNALS   EMULATING MATCHED FILTER OPERATION#HAPTER . ÓÎ°Ó  2!$!2 (!.$"//+  "ISTATIC TARGET LOCATION USES A PROCESS DIFFERENT FROM THAT OF A MONOSTATIC RADAR )N A  TYPICAL IMPLEMENTATION  THE BISTATIC RADAR MEASURES A  THE TRANSMITTER 
 Entries 6 to 8 are of interest primarily be- cause of the sidelobe falloff rate. The falloff rate can be shown to be related to the manner in which the frequency function and its derivatives behave at cut- off points,/= ±J0/2.46'47 Taylor versus Cosine-Squared-Plus-Pedestal Weighting. Figure 10.160 plots the taper coefficient F1 and pedestal height H versus the peak sidelobe level for cosine-squared-plus-pedestal weighting. 
 Ingeneral, however, the frequency ofthe reply will bedifferent from that ofthe triggering radar set. Inorder toreceive such replies, one needs areceiver tuned to thefrequency ofthepulses sent out bythe beacon instead oftothefre- quency oftheinitial transmitted pulses. This may beeither thereceiver ofthe radar settuned tothe new frequency, orasecond independent receiver tuned tothebeacon. 
 The distribution A(z) across a  continuous aperture was given by Eq. (7.14).  (7.14)254INTRODUCTION TORADAR SYSTEMS Evaluation oflensesasantennas. 
 Targets    RCS  [m2]   RCS  [dB]     Jumbo Je t 100 20  jet airliner  20 … 40  13 … 16   large fighter  6 7.8  helicopter  3 4.7  four-passenger jet  2 3  small aircraft  1 0  stealth jet  0.1 … 0.01  -10 … -20  Table 1: Examples of Radar Cross Section     . Radartutorial (www.radartutorial.eu)   13    Figure 18: Non -directional power density  diminishes as geometric spreading of the  beam.  Free -space Path Loss   R is the target range of the term in the equation. 
 Clutter Return: General Equations.  The clutter-to-noise ratio from a single  clutter patch with incremental area dA at a range R is  C NP G G d A R L kTBT R C s n=av λ σ π2 0 3 44( ) (4.2) where  Pav = average transmit power  GT  = transmit gain in patch direction  GR  = receive gain in patch direction  l  = operating wavelength  s  0  = clutter backscatter coefficient  LC  = losses applicable to clutter  k  = Boltzmann’s constant = 1.38054 × 10−23 W/(Hz/K)  Ts  = system noise temperature, K  Bn  = doppler filter bandwidth LC refers to losses that apply to distributed surface clutter, as opposed to discrete,  resolvable targets. These losses will be discussed in Section 4.6. 
 In many forms of radar the tme relationship  between the transmitted burst and the received packet  of energy, and the accurate measurement of this time  relationship, is as important as the reception of the echo.  Thus the time-base of the CRT is so arranged that the  echo is presented not, as it were, on one continuous  beam of fluorescence, but with each echo on a separate  trace. The whole thing takes place dozens or hundreds  or even thousands of times every second, so to the  human eye it appears as a continuous process. 
 ( after W. G. Bath et al.32) ch07.indd   25 12/17/07   2:13:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Lenses which must scan by positioning the feed should also have large f/D ratio. A large  flD requires a greater mechanical structure because the feeds are bigger and must be supported  farther from the lens. The mechanical sapport of a lens is usually more of a problem than with  a reflector. 
 Itshould benoticed that the two effects change together asthe PRF isvaried. Aquestion ofsome interest isthefollowing: Ifatarget ofgiven size can have any radial speed with equal probability, how often will itbe detected? Let ussuppose that the target, when moving atone ofthe optimum speeds inFig. 16.21, gives asignal Ntimes aslarge asthemini- mum detectable signal. 
 POWER PULSE  TYPICALLY ONE 
 D. E. Kerr, Propagation of Short Radio Waves , New York: McGraw-Hill Book Company, 1951. 
 Contents FOREWORD EIYL.A.DUBMDGE vii PREFACE ............... .ix CHAP. 1.INTRODUCTION ............... 
 The simple MT1 radar sliown in Fig. 4.lh is not necessarily the most typical. The block  diagram of a rnorc common MTI radar employing a power amplifier is shown in Fig. 
 The Fourier series may be used to synthesize the pattern of a discrete array, just as the  Fourier integral may be used to synthesize the pattern of a continuous apert~re.'~ Similar  conclusions apply. The Fourier-series method is restricted in practice to arrays with element  spacing in tlie vicirlity of a half wavelength. Closer spacing results in supergrain arrays which  are not 75.76 Spacings larger than a wavelength produce undesired grating lobes. 
 Theaccuracy ofrangetracking, however, isaffectedbythelossinsignalbutnotby theslopeatthecrossover point.Therefore, asacompromise between therequirements for accurate rangeandangletracking, acrossover nearerthepeakofthebeamisusuallyselected ratherthanthatindicated fromFig.5.6.Ithasbeen·suggested thatthecompromise valueof 0,/08beabOut0.28,corresponding toapointontheantenna patternabout1.0dBbelowthe peak.1.2 Otherconsiderations. Inboththesequential-Iobing andconical-scan techniques, themeasure­ mentoftheangleerrorintwoorthogonal coordinates (azimuth andelevation) requiresthata minimum ofthreepulsesbeprocessed. Inpractice, however, theminimum numberofpulsesin sequential lobingisusuallyfour-one perquadrant. 
 ERL  70-ITS 76, U.S. Govt. Printing Office, Washington, DC, 1968. 
 TICULAR RADAR DEPLOYMENT IS VITAL TO RADAR DESIGN  AS WELL AS PROVIDING A GUIDE TO ECHO INTERPRETATION AND A MEANS TO SIMULATION AND PERFORMANCE PREDICTION 4HIS TYPE OF INFORMATION  BASED ON DECADES OF  IONOSPHERIC OBSERVATIONS AND THEORY  IS CONVENIENTLY  DISTILLED IN MODELS THAT ARE WIDELY AVAILABLE AND USED EXTENSIVELY "UT EVEN MORE IMPORTANTLY  FROM THE OPERATIONAL PERSPECTIVE  (& RADARS MUST MAINTAIN A REAL 
 W. Schaefer, Digital signal processing , Englewood Cliffs, NJ:   Prentice-Hall, 1975. 87. 
 51-56. Apr. 22. 
 Microwave Techniques, Paris, March 5, 1962. 31. V . 
 130. Clarricoates, P. J. 
 The time required toexplore this zone is approximately 3sec. Amarriage ofthe horizon scan(or,alternatively, the sector scan). 282 ANTENNAS, SCANNERS, ANDSTABILIZATION [SEC. 
 BAND !342/-ESH REFLECTOR WITH  METER  CIRCULAR PROJECTED APERTURE #OURTESY .ORTHROP 'RUMMAN #ORPORATION .   2%&,%#4/2 !.4%..!3   £Ó°Î $EPLOYABLE SPACE 
 LAW DETECTOR HAS BEEN PRESENTED BY .ITZBERG   4HESE AND OTHER RESULTS CAN BE SUMMARIZED INTO A SINGLE UNIVERSAL CURVE OF CLUTTER MAP LOSS  , #-  AS A FUNCTION OF THE CLUTTER MAP RATIO  X,EFF  AS SHOWN IN &IGURE   WHERE   X DEFINES THE REQUIRED FALSE 
 TIME ADAPTIVE ARRAY PROCESSING COMBINES A TWO 
 SING INTO THE NEAR ZONE v IN h0HASED !RRAY !NTENNAS v ! ! /LINER AND ' ( +NITTEL EDS    .ORWOOD  -! !RTECH (OUSE    PP n  $ + !LEXANDER AND 2 0 'RAY  *R  h#OMPUTER 
 (Yaolin Liu). Acknowledgments: This research was ﬁnancially supported by the National Natural Science Foundation of China (No. 41771432). 
 These were shown as ‘black-out ’marks and could be selected by a pull-out switch on the range scale knob; edge lighting of the range scale, from the left for 3 or 30 mile scales and from the right for 12 or 120 mile scale; provision for IFF suppression; input for strobe indication. The various indicating units are shown in ﬁgure 2.13. 2.2.2.6 Pilot ’s indicator There was a continuing operational requirement during 1940 and 1941 to provide a pilot ’s indicator display. 
 The airborne doppler navigator radar is also based on the  doppler shift. The use of doppler in a radar generally places greater demands on the  stability of the radar transmitter, and it increases the complexity of the signal process - ing; yet these requirements are willingly accepted in order to achieve the significant  benefits offered by doppler. It should also be mentioned that the doppler shift is the key  capability of a radar that can measure speed, as by its diligent use by traffic police for  maintaining vehicle speed limits and in other velocity measuring applications. 
 Alabama, Tedlllical ReportRR-77-J. November. 1976.(Distribution unlimited.) 118.Rogers. 
 SECTION OF THE 'UYANA RAIN FOREST POSSIBLE  USE AS A REFERENCE TARGET FOR SPACEBORNE RADARS v  2EMOTE 3ENSING OF %NVIR  VOL   PP n     2 + -OORE AND - (EMMAT  h$ETERMINATION OF THE VERTICAL PATTERN OF THE 3)2 
 Perry, “A wideband linear fm ramp generator for the long-range imag - ing radar,” IEEE Trans, Microwave Theory and Techniques , vol. MTT-26, no. 5, pp. 
 ÓÎ°£Ó  2!$!2 (!.$"//+  4ARGET LOCATION IS ESTABLISHED BY TRIANGULATION  IE  THE INTERSECTION OF ZENITH ANGLE  $/!  MEASUREMENTS FROM TWO OR MORE RECEIVE SITES 3UBSEQUENTLY A THREE 
 Shift registers are used for dig i- tal integration.  The advantage of the tapped delay line is that any weighting of the ta ps is pos- sible, for example, in order to strengthen the wanted pulses or weaken the older pulses.   1 2 nTapped delay line Video in Integrated output  Figure 8.16  Incoherent integrator with a tapped delay line. 
 TO 
 Bar-Shalom and   W. D. Blair (eds.), Norwood, MA: Artech House, Inc., 2000, pp. 
 Most frequency domain processing requires  relatively long IQ data sample sets for discrete Fourier transform analyses, window  functions, and possible spectral averaging to obtain spectra suitable for quantita - tive processing.102 Faster scanning radars used for sampling rapidly evolving storms  requires spectrum analysis techniques that use short dwell time data sets of many fewer  IQ data samples. Modern spectrum analysis techniques such as the Burg maximum  entropy103 and the Capon104 maximum likelihood estimators allow using short dwell  sampled data to obtain stable spectrum estimators. These techniques belong to the  general class of autoregressive (AR) estimators whereby the observed data are mod - eled as all-pole filtered white noise rather than a weighted sum of sinusoids according  to the Fourier model.105 Multiple signals and ground clutter may be resolved the same  as using Fourier estimators. 
 7.3.2.2 Modelling results With these modelling methods available, as explained in more detail in [ 6], we can now model the performance of these radars and compare the results of modelling with trials. A simple comparison of noise-limited detection can be made by considering a ﬁgure of merit based on the ratio of values of PNp/ r n, taken from (7.1) and ( 7.2). Using the values in table 7.1and taking the performance of ASV Mk. 
 Additional isolation can be obtained by properly introducing a controlled sample of the  transmitted signal directly into the receiver. The phase and amplitude of this" buck-off" signal  are adjusted to cancel the portion of the transmitter signal that leaks into the receiver. An  additional 10 dB of isolation might be obtained.12 The phase and amplitude of the leakage  signal, however, can vary as the antenna scans, which results in varying cancellation. 
 Poggio, “Numerical electromagnetic code (nec)-method of moments,”  NOSC Tech. Doc.  116, 1981. 
 During the war, itlacked the systematic study that its importance and itscomplexity deserved. Since any treat ment ofsystem design would beincomplete without some reference tothis important topic, this chapter will deal briefly with some ofthe devices and some of themethods which have been worked outtotranslate into commands the decisions taken onthebasis ofradar information. 1 Itistobeemphasized that this subject isatleast asdifficult and as important asthat ofthetechnical design ofthe radar itself, and farless well understood. 
 Davis, “Principles of electronic warfare: Radar and EW,” Microwave J ., vol. 33, pp. 52–54,  56–59, February 1980. 
 VENIENT AT THE SUBARRAY LEVEL /N RECEIVING  THE NOISE FIGURE IS ESTABLISHED BY THE &)'52%   0ARALLEL 
 Severalnonarray techniques usingreflectors orlenseshave beenconsidered forthegeneration ofmultiple beams.TheLuneburg lensandthetorus reflector withmultiple feedsasdescribed inChap.7areexamples. Aradarwithareflector antennadesigned togenerate aclusterofmanybeamshasbeensometimes calledapincllshion radar. Inoneexample ofadevelopmental radarthatgenerated multiple beams.aspherical transmitting antenna wassurrounded bythreespherical Luneburg-lens receiving antennas, eachcovering aone-third sectorofspace.'05Thetransmitting antennawasaspherical phased arrayofseveralthousand elements. 
 iVÌÀVÊÊ  ÕÌiÀ ÕÌiÀi>ÃÕÀiÃ °Ê>À> !NALYSIS OF )NTEGRATED 3YSTEMS   3%,%8 3ISTEMI )NTEGRATI Ó{°£Ê  /," 1 /"  3INCE 7ORLD 7AR ))  BOTH RADAR AND ELECTRONIC WARFARE %7    HAVE ACHIEVED A VERY  HIGH STATE OF PERFORMANCE  -ODERN MILITARY FORCES DEPEND HEAVILY ON ELECTROMAGNETIC  %-  SYSTEMS FOR SURVEILLANCE  WEAPON CONTROL  COMMUNICATION  AND NAVIGATION THUS  ACCESS TO  AND CONTROL OF  THE %- SPECTRUM IS VITAL %LECTRONIC COUNTERMEASURES %#-  ARE LIKELY TO BE TAKEN BY HOSTILE FORCES TO DEGRADE THE EFFECTIVENESS OF %- SYSTEMS n  !S A DIRECT CONSEQUENCE  %- SYSTEMS ARE MORE AND MORE FREQUENTLY EQUIPPED WITH SO 
 Kähny" "Basic polarimetric meas urements on  monostatic or bistatic radar images", W.- M. Boerner et al. (eds.) : Direct and Inverse  Methods in Radar Polarimetry, Part 1, pp. 
        . Óx°n  2!$!2 (!.$"//+  WHERE F,/    -(Z 3IMILARLY  USING    FOR TIME 
 7, pp. 83-90, December, 1964.  21. 
 CONTROLLED RECTIFIER 3#2   REVERSE 
 The accuracy of all radar measurements, as well as the  reliable detection of targets depends on the ratio E/No, where E is the total energy  of the received signal that is processed by the radar and No is the noise power per  unit bandwidth of the receiver. Thus E/No is an important measure of the capability  of a radar. Operation with More Than One Frequency. 
 On a world average,  the evaporation duct height is approximately 13 meters. It should be emphasized that  the evaporation duct “height” is not a height below which an antenna must be located  in order to have extended propagation but a value that relates to the duct’s strength  or its ability to trap radiation. The duct strength is also a function of wind velocity. 
 143. S. B. 
 Weiss: Behavior and Application of Ferrites in the Microwave  Region, Bell Sysrrm Tech. J., vol. 34, pp. 
 MICIIOWAVE !vfIxERs-Pound 17. COMPONENTS HANDBooK—Blackburn 18. VACUUM TUBE AMPLIFIERS—~’U@ and Wa!lman 19. 
 LEVEL $"& REQUIRES A DIGITAL  RECEIVER AT EACH SUB 
 S. Ament, “Forward and backscattering by certain rough surfaces,” Trans. IRE , vol. 
 SECOND TIME HISTORIES OF RETURNS FROM A FIXED SPOT  MEASURED OFF THE COAST OF &LORIDA WITH A VARIABLE 
 TO 
 We  need a ‘sharp-edged,’ staccato sound to make the clean  echo. By wiring our CRT to appropriate parts of our  transmitter we can deflect the spot in exact sympathy  with the type of wave-form being produced by voltage  changes in each circuit. We can actually see the shape  of the outgoing pulse, and on most equipments it will  show up in the form of U or VY. 
 This requires that the intermediate cavities and the  input cavity of such a tube be stagger-tuned to accommodate the increased bandwidth  offered by the output circuit. Because this type of tube is part klystron and part TWT,  it was named Twystron . The V A-145 S-band Twystron has a bandwidth of 14% with  a 35% efficiency, 41 dB gain at midband, peak power of 3.5 MW, and average power  of 7 kW.19 Extended Interaction Klystron (EIK) . 
 Pseudo-Monostatic RCS Region. The Crispin and Siegal monostatic-bistatic equivalence theorem applies in the pseudo-monostatic region:36 for vanishingly small wavelengths the bistatic RCS of a sufficiently smooth, perfectly conducting target is equal to the monostatic RCS measured on the bisector of the bistatic angle. Sufficiently smooth targets typically include spheres, elliptic cylinders, cones, and ogives. 
 Insomeapplications acomplete raytraceisnotnecessary; instead, onlytheamount by whichtheraysarebentmightbedesired, ortheerrorinelevation anglewhichoccurs.A correction tothemeasured elevation anglecanbemadeusingonlythevalueoftheindexof. 456 INTRODUCTION TO RADAR SYSTEMS  refraction at the surface,20." obtained with either a microwave refractometer or from meteor-  ological measurements of temperature, pressure, and humidity. An improvement to the eleva-  tion angle correction can be had by making a measurement of the brightness temperature of  the atmosphere with a microwave radiometer, along with a surface refractive-index  rneasi~rernent.~~ Since refractive bending and radiometric bright ness-temperat i~rc measure-  ments both depend on the atmospheric profile, the use of the radiometer provides information  that aids in the correction of elevation angle. 
 Gemini and Apollo programs demonstrated the first operational experience with the rendezvous maneuver. The successful performance of the rendezvous radars in these programs effectively opened the door to many possi- ble missions that may be performed in space. The Ku-band integrated radar and communications subsystem (IRACS), designed for the space shuttle orbiter ve- hicle, demonstrated the rendezvous, satellite retrieval, and station-keeping mis- sions. 
 Further discussion on the integration of the Leigh Light with ASV Mk. VI can be found in chapter 4. 2.2.7 Disappearing contacts After initial success in the use of ASV Mk. 
 In either case, the rest of the receiver and signal processing is the same as for a CW system. The seeker implementation follows this same pattern. However, range gating in the seeker is generally not used with a high-duty-cycle system. 
 12, McGraw-Hill Book Compa~\y, New York, 1949.  2. Krat~s. 
 TION IMPOSES A DOPPLER SHIFT ONTO THE RECEIVED DATA  &ROM LOW %ARTH ORBIT ,%/   THE  MAGNITUDE OF THIS SHIFT IS ON THE ORDER OF  n  AND TO FIRST ORDER  VARIES SINUSOIDALLY  WITH LATITUDE  WITH MAXIMUM MAGNITUDE AT THE EQUATOR  AND WITH ZERO AT THE EXTREME  . AND 3 LATITUDES 4HE EFFECT CAN BE OFFSET BY YAW 
 We have seen that the distance  along the time-base where the echo blip displays itself  is a true indication of distance of the target from the  pulse transmitter. Thus we can read the range, but  without some other means we do not know direction;  also, if our target is an aircraft, we cannot read its  height from the simple Type A display. Moreover, the  range of the echoing object must be read with some  degree of accuracy by taking a measurement on the  trace from the leading edge of the transmitter pulse to  the leading edge of the echo blip. 
 .- C ..  OI a  c -30- 0 -  U S  Lo $ -40  U  - 50  - 60 1" 3" 5" 10" 30" 50" 90"  Grazing angle  (a  I I I I I Ill I I I I Ill'  -  -  - -  Arizona mountainous  -  Arizona desert  N. J marshland  Delaware Bay  - 1  .-  L ""  I I I I I I Ill 1 I I I Ill  lo 3" 5" 10" 30" 60" 90"  Grazing ongle  (b)  492INTRODUCTION TORADAR SYSTEMS J NJrural 10° Grazingangle (b)Arizonadesert ,",-_~~::::;:;::;::::::::;:1""""" N.J.marshland Delaware Bay10° Grazingangle (a)Delaware Bay PhoenixNJ.residential Arizona mountainousPhoeniX~~~~~:::~;;~~~§~~~;;;=i~:13 Arizonadesert 0 AmonamountainOus K-_--<J NJ.marshland10 0 CD'0-10 °b ci <1J0-20 ·c :0 Ii; 0- c-30a ~ 1I1 1I1 1I1e-40u -50 -60 1° 10 0 CD-10-:g °b ci ~-20- 0 E :0 Q; 0- c-30a "5 <1J 1I1 1I1 1I1-40- a U -50- -60 1° Figure13.9Median valuesof(10forvariousterrain:(a)Xband,verticalpolarization, (h)Lband,vertical polarization, (c)Xband,horizontal polarization, (d)Lband,horizontal polarization. 
  
 TIME OPERATION 4HE FUNCTIONAL BLOCK DIAGRAM AND OPERATION OF A SPECIFIC SENSOR MODE IS THEN OVER 
 In the H-plane metal-plate constrained  letis. tlie electric field is perpendicular to the plates (H field parallel); thus the velocity of the  wave wliicli propag;ites tlirougli tlie plates is relatively unaffected provided the plate spacing is  Figure 7.20 .Y-hand metal-plate zoned lens.  RADAR ANTENNAS 251 whereAisthewavelength inair.Equation (7.21)isalwayslessthanunity.Attheupperlimitof spacing. 
 The function of the doppler frequency is  provided by modulating the retransmitted signals at the remote unit in such a manner that a  I -k Hz beat frequency is obtained from the heterodyning process at the receiver of the master  unit. Tile phase ofthe I-kf-iz signals coritains the same information as the phase of the multiple  frequeqcies.  7 re MRB 201 Tellurometer is capable of measuring distances from 200 to 250 km,  assuming reasonable line of sight conditions, with an accuracy of 10.5 m 1 3 x d,  where d is the distance being measured. 
 - 2EFLECTOR ANTENNAS ARE BUILT IN A WIDE VARIETY OF SHAPES AND SIZES WITH A CORRESPONDING  VARIETY OF FEED SYSTEMS TO ILLUMINATE THE SURFACES   EACH SUITED TO ITS PARTICULAR APPLI 
 However, manypulses arcusuallyrctlllllcd fromanyparticular targetolleachradarscanandcanhcusedtoimprove detection. ThelIumber ofpulsesilln)returned fromapointtarge.tastheradarantcnna scans through itsbeamwidtlL is(/' L.-.:'t,,;'".-_..~. C;',-\",''\;... 
 D.: Colour Displays in Air Traffic Control, International Conference on Displays for  Man-Machine Systems, Apr. 4-7, 1977, IEE (London) Conference Publication no. 150, pp. 
 SCAN -ODERN DIGITAL TECHNOLOGY  WITH ITS PROCESSING SPEED  AVAILABLE WORD LENGTH  AND LARGE MEMORY CAPABILITY  ALLOWS THE RADAR DESIGNER TO HAVE GREAT FLEXIBILITY IN THE STRATEGY APPLIED  AND WHAT ARE ENTIRELY SEPARATE PRO 
   )NTERNATIONAL 4ELECOMMUNICATION 5NION  'ENEVA  h-ARITIME NAVIGATION AND RADIOCOMMUNICATION EQUIPMENT AND S YSTEMS#LASS " SHIP 
 This might be accomplished with  (D  u  ...  0 u  0 .....  c  ID  E «> > 0  0. 
     
 Mostpropagation effectsthatareofimportance cannotbeeasilyincluded intotheradar equation. Theymustbeproperly takenintoaccount, however, sincetheycanhaveamajor impactonperformance. Furtherdiscussion oftheeffectsofpropagation onradarisgivenin Chap.12. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.70  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 dBc/Hz values in Figure 2.78 correspond to 10⋅log( )S. Further denoting the phase  noise spectral density relative to the carrier at the end of the segment as S2 (Hz–1), the  slope is defined by  α=log ( / ) log ( / )10 2 1 10 2 1S S f f (2.43) The slope in dB/decade is equal to 10⋅α. 
 May. 1973.  29. 
 LIKE INTERFERENCES 4HE RIGHT 
 SIBLE TARGET RADIAL VELOCITIES FOR ALL #0)S ARE THEN SORTED INTO A SINGLE LIST  AND THE MOST  LIKELY TRUE RADIAL VELOCITY IS FOUND WHERE AT LEAST TWO POSSIBLE VELOCITIES FALL WITHIN AN INTERVAL LESS THAN TWO OR THREE TIMES THE STANDARD DEVIATION OF THE DOPPLER FREQUENCY ESTIMATE 4HE TIGHTNESS OF THE CLUSTER OF NEARLY IDENTICAL VELOCITIES IN CONJUNCTION WITH THE NUMBER OF #0)S CONTRIBUTING TO THE CLUSTER CAN BE UTILIZED AS A MEASURE OF RELIABILITY OF THE UNAMBIGUOUS RADIAL VELOCITY ESTIMATE    4HIS APPROACH WAS FIRST BROUGHT TO THE ATTENTION OF THE AUTHORS BY $R "EN #ANTRELL OF THE 53 .AVAL 2ESEARCH  ,ABORATORY.   -4) 2!$!2  Ó°£ #OMMENTS 4HE ABOVE PROCEDURE FOR DETERMINING TRUE RANGE AND TRUE RADIAL  VELOC 
 LINE 4HESE ARE SHOWN DIAGRAMMATICALLY IN &IGURE  4HE SWITCHED 
 Other Applications.  A highly significant application of radar that provided  information not available by any other method, was the exploration of the surface  of the planet Venus by an imaging radar that could see under the ever-present clouds  that mask the planet. One of the widest used and least expensive of radars has been  the civil marine radar found throughout the world for the safe navigation of boats and  ships. 
 (This assumes that the clutter-velocity spectrurn  width n,. is the same for both carriers, or a, = i.a2 where a, and o2 are the clutter doppler-  frequency spreads. This results in less improvement factor for a two-frequency MTI as  compared witti a single-frequeticy MTI. 
 TRUTHv INFORMATION AND ACCURATELY CALIBRATED THEIR RADARS -OREOVER  THESE DATA WERE OVER A WIDE RANGE OF FREQUENCIES 6(&  -(Z   5(&  -(Z   , BAND  '(Z   3 BAND  '(Z   AND 8 BAND  '(Z  4HEY HAD  DIFFERENT TARGET AREAS IN DIFFERENT PARTS OF THE 53 AND WESTERN #ANADA. 
 4rrA,.  (i = ---.z-­,l  fla = antenna aperture efficiency (7.9)  Polarization. The direction of polarization is defined as the direction of the electric field  vector. 
 Brit. IRE, voi. 17, pp. 
 DIMENSIONAL COVARIANCE MATRIX   -   %6  64   WHERE %  DENOTES THE STATISTICAL EXPECTATION  THE ASTERISK     INDICATES  THE COMPLEX CONJUGATE  AND  64 IS THE TRANSPOSE VECTOR OF  6 4HE STATISTICAL RELATIONSHIP  BETWEEN 6- AND 6 IS MATHEMATICALLY REPRESENTED BY THE  . 
 Values of K1 for ice and water clouds are given for various wavelengths and temperatures by Gunn and East in Table 23.1. Several important facts are demonstrated by Table 23.1. The decrease in at- tenuation with increasing wavelength is clearly shown. 
 Combinations.   Combinations of these remedies can be considered. For exam - ple, a fixed multibeam receive antenna can be used with a fixed floodlight transmit  antenna. 
 Sensors 2019 ,19, 3344 Pulsars are located on thousands of light years from Earth and can be considered as uninterruptible sources of electromagnetic waves. It allows the object illuminated by the pulsar beam as an asteroid orspacecraft, to be considered as a secondary emitter in compliance with Babinet’s principle. The di ﬀracted electromagnetic ﬁeld is a superposition of partial ﬁelds reemitted by all illuminated parts of the asteroid and carries information concerning its geometry and kinematics as a moving rigid body. 
 1994 ,30, 827–835. [ CrossRef ] 15. Qing, J.; Xu, H.; Liang, X.; Li, Y. 
 E.: "Radar Design Principles," McGraw-Hill Book Co., New York, 1969.  48. Goldstein, H.: The Effect ofCluner Fluctuations on MTl; MIT·Radiacion Lab. 
 J. A.: Spiral Antennas Applied to Scanning Arrays, Electronic Scanning Symposium, Apr.  29-JO. 
 &ANBEAMS # 66.3#!4 !$%/3 ) 53*APAN n &ANBEAMS +U 66  ((3EA7INDS 1UIK3#!4 53 n #ONICAL SCAN +U 66  ((3EA7INDS !$%/3 )) 53*APAN n #ONICAL SCAN +U 66  ((#.3#!4 3: 
 Kroc/c7ynski, J.: The Two-Frequency MTI System, The Radio attd Elrctrot~ic Etrgit~err. vol. 39. 
 Research andDcvelopment. EASCON-77 RECORD. pp.411\ to4II.Sepl.2(JlX.11}77.Arlington. 
 S THE # 
 on Radar , Beijing, October 2001. 149. G. 
 3AMPLING #ONSIDERATIONS  !CTUAL DEVICES AND SIGNALS INTRODUCE ERRORS  &OR EXAMPLE  CLOCK JITTER RESULTS IN ERRORS IN THE SAMPLED OUTPUT OF AN !$#  AS SHOWN IN &IGURE  )N ADDITION  REAL !$#S ALSO ADD INTERNAL JITTER  OR  APERTURE UNCERTAINTY   WHICH MUST BE TAKEN INTO ACCOUNT  )F THE ERRORS IN THE EFFECTIVE SAMPLING INSTANT INTRO 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Thus, the component of the surface that satisfies the Bragg resonance condition is  Λ = l/2 sin q (16.8) This means that the most important contributor to a surface return is the component of  surface roughness with wavelength Λ. 
 Remote Sens. 2011 ,49, 1092–1103. [ CrossRef ] 2. 
 --------——. --,--.-—— .-.-—. —. 
 FREQUENCY SIGNAL TO BE SAMPLED BY A RELATIVELY LOW 
 FREQUENCY WATER 
  
 When birds travel in flocks.  the total cross section can be significantly greater than that of a single bird. Because the radar  screen collapses a relatively large volume of space onto a small radar screen, the display can  appear cluttered with bird echoes even though only a few birds can be seen by visual examina­ tion of the surrounding area. 
 Each of these beacons transmits on a different frequency |  (or, in a certain variation of the system, on the same  frequency, but with different PRF’s), and each is given  a different CRT display in the cockpit. In certain  equipment where there is no CRT display miliammeter  needles show what is happening. With milliammeter  display the instruments used are of the. 
 sensors Article Improving the Accuracy of Two-Color Multiview (2CMV) Advanced Geospatial Information (AGI) Products Using Unsupervised Feature Learning andOptical Flow Berkay Kanberoglu1,* and David Frakes2 1School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ 85281, USA 2School of Biological and Health Systems Engineering, Arizona State University, Tempe, AZ 85281, USA; dfrakes@asu.edu *Correspondence: bkanbero@asu.edu Received: 5 May 2019; Accepted: 3 June 2019; Published: 8 June 2019/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: In two-color multiview (2CMV) advanced geospatial information (AGI) products, temporal changes in synthetic aperture radar (SAR) images acquired at different times are detected, colorized, and overlaid on an initial image such that new features are represented in cyan, and features that have disappeared are represented in red. Accurate detection of temporal changes in 2CMV AGI products can be challenging because of ’speckle noise’ susceptibility and false positives that result from small orientation differences between objects imaged at different times. Accordingly, 2CMV products are often dominated by colored pixels when changes are detected via simple pixel-wise cross-correlation. 
 A. (ed.): "Fundamentals of Over-the-Horizon Radar," in Russian, Radio i svyaz, 1984. Also a translation by W. 
 RANGE AIR 
 The two assumed rates are (1) a relatively slow fluctuation, such that the values of a for successive scans of the radar beam past the target are statistically independent but remain virtually constant from one pulse to the next, and (2) a relatively fast fluctuation, such that the values of cr are independent from pulse to pulse within one beamwidth of the scan (i.e., during the integration time). The first of the two assumed distributions for the received-signal voltage is of the Rayleigh form,* which means that the target cross section cr has a probability density function given by *The Rayleigh density function for a voltage v is /x 2V - V2Ir2p(v) =-^e where r is the rms value of v. DETECTABILITY FACTOR D0 (DECIBELS) . 
 488 INTRODUCTION TO RADAR SYSTEMS  Sea clutter has a Rayleigh pdf when the resolution is low. (A low-resolution radar in this  case might have a 5" beamwidth and 1-jts pulse width.") With better resolution the pdf of sea  clutter deviates from Rayleigh and the log-FTC receiver is no longer CFAR. A variant  sometimes useful for reducing the false-alarm rate in non-Rayleigh clutter is the log-log  receiver. 
 AN/TPS-43E Tactical Radar System, brochure, Westinghouse Corporation. 14. The Martello High Power 3-D Radar System, brochure, Marconi Company. 
 W. Benner, W. G. 
 MENTATION RADARS AT ONE TIME DEVELOPED PEAK SIGNAL POWERS RANGING FROM  TO  K7 . £{°ÎÓ  2!$!2 (!.$"//+  4HE HIGH 
 Avery important requirement, inpractice, isdiscrimination against isolated but powerful disturbances such astransients from nearby electrical apparatus, or,very commonly, pulse interference from other radar sets. Indeed, thefrequency ofsuch disturbances, inmost locations, renders academic our earlier remarks about the likelihood ofgetting anabnormally high noise peak once an hour orso. The fact that the desired signal occurs repeatedly allows such isolated disturbances tobediscarded easily, ordisregarded. 
 89.Levine,D.:"Radargrammetry," McGraw-Hill BookCo.,NewYork,1960. 90.Shanks, H.E.:AGeometrical OpticsMethod ofPattern Synthesis forLinearArrays,IRETrailS, vol.AP-8,pp.485-490, September, 1960. 91.Hutchison, P.T:TheImageMethodofBeamShaping, IRETrailS.,vol.AP-4,pp.60~609,Octoba. 
 It is an integrated bandwidth and is  given by  (' I H(f) 12 df  Bn = . -ail H(fo) 12 (2.3)  where H{f) = frequency-response characteristic of IF amplifier (filter) and Jo = frequency of  maximum response (usually occurs at midband).  When H(f) is normalized · to unity at midband (maximum-response frequency). 
 The biggest field for the present of the true electronic  navigational aids is held by Gee, G-H, and Oboe, and  they all had their beginnings in the years when long-  range radar navigational aids were vitally necessary to  ‘guide bombers over enemy targets, and to bring them  safely back.  On the face of things Gee appears so similar to non-  pulse methods that it merits a close inspection to avoid  this confusion. Ever since radio direction-finding  became practicable it has been used to provide ships  and aircraft with a knowledge of their position relative  to fixed points. 
 13.1la). The load may beinthe plate, itmay bethecathode resistor, oritmay bedivided between plate and cathode circuits toprovide two output points. For aplate load, thefeedback voltage isactually proportional tothe current through theload’ rather than tothevoltage across it;this iscalled “current feedback.” Ifthe load current isofinterest (asindriving a deflection coil), this isjust what iswanted. 
 W. James: Practical Methods for Observing and Forecasting Ocean Waves by Means of Wave Spectra and Statistics, H.O. Pub. 
 Thus, for example, av of rain viewed at 25 nmi with a vertical beamwidth of 4° would have a crv = 4.1 m/s, of which the shear component is dominant. Rain and chaff also have an average velocity, in addition to the spectral spread noted above, which must be taken into account when designing an MTI system. The clutter spectral width in meters per second is independent of the radar frequency. 
 This study can be used for performing space object navigation, localization and imaging based on pulsar emission. 2.2. Ground-Based SAR The special issue includes also three interesting papers [ 8–10] dedicated to ground-based SAR (GBSAR) systems. 
 The purpose of the threshold is to divide the output into a region  of no detection and a region of detection; or in other words, the threshold detector allows a  choice between one of two hypotheses. One hypothesis is that the receiver output is due to  noise alone; the other is that the output is due to signal-plus-noise. It was shownjn Chap. 
    PP n    * * 3TEIN AND 3  3 "LACKMAN  h'ENERALIZED CORRELATION OF MULTI 
 Because the cross-range coordinate of the resulting image is perpendicular to the axis  of rotation of the target, it may be necessary to multiply that coordinate by a scale factor  that effectively registers the generated image with, say, a plan view of the target. The resulting data may be presented in the form of a contour map, as in Figure 14.25,  or in a color-coded or grayscale pixel format. Here, the target outline has been super - posed on the image data for diagnostic analysis, and the particular attitude shown is  for nose-on incidence. 
 OPPORTUNITY IN MILITARY SCENARIOS CAN BE DESIGNATED  EITHER COOPERATIVE OR  NONCOOPERATIVE  WHERE COOPERATIVE DENOTES AN ALLIED OR FRIENDLY  TRANSMITTER AND NONCOOPERATIVE DENOTES A HOSTILE OR NEUTRAL TRANSMITTER "ISTATIC TARGET DETECTION USES A PROCESS SIMILAR TO THAT OF A MONOSTATIC RADAR   WHERE THE TARGET IS ILLUMINATED BY A TRANSMITTER AND TARGET ECHOES ARE RECEIVED  DETECTED  AND PROCESSED BY A RECEIVER 7HEN OPERATING WITH TRANSMITTERS USING #7 OR HIGH 
 Theoptimum elliptical polarization depends onthenatureoftherain.This dfectisduetothenonspherical raindrops whichcausethephaseshiftandattenuation ofthe radarenergytobedifferent depending onthedirection ofpolarization. Astheradarenergy propagates through therain,thedifferential phaseshiftandthedifferential attenuation results inthecircular polarization beingconverted toelliptical polarization. Byselecting theoptimum elliptical polarization. 
 The  more slowly the radar antenna scans, the more pulses will be available for integration and the  better the detection capability. On the other hand, a stow scan rate means a longer time  hetwcen looks at the target. Scan rates of practical search radars vary from 1 to 60 rpm, 5 or  6 rpm being typical for the long-range surveillance or aircraft. 
 and H. V. Hitney: The Effect of the Evaporation Duct on Microwave Propagation,  Narwl Electro~tics Laboratory Certter, San Diego, California, Technical Report 1949, Apr., I7 1975. 
 DUCED BY THE MOVEMENT OF THEIR EQUIVALENT SCATTERERS ÓÓ°£äÊ 6 
 ................................ .... 2  Preamble  ................................ 
 Each country eventually progressed to pulse radar  operation and the advantages pertaining thereto. Although the advantages of the higher  frequencies were well recognized, except for the United States and Great Britain none of the  others deployed radar at frequencies higher than about 600 MHz during the war.  The Germans deployed several different types of radars during World War II. 
 Labels I (in-phase) and Q (quadrature) are traditionally used to indicate the real  and imaginary parts of complex time-domain signals, like those here, that are realized  as pairs of real signals. When a vertical cut through a diagram, such as in Figure 25.9,  picks up one I signal and one Q signal, the represented complex signal crossing that  cut is I + jQ. In the diagram, cuts just before and after the LPF blocks pick up complex   signals with the spectra shown on lines 3 and 5 of Figure 25.8, respectively. 
 Voltage-Controlled Oscillator. A voltage-controlled oscillator (VCO) is a frequency generation device in which the frequency varies with an applied voltage. Ideally, the frequency is a linear function of the applied voltage, but most devices have a linearity error of over 1 percent. 
 (3) GaAs is a poor thermal conductor. Power FET design that addresses  thermal management is required. Adequate heat sinking of the chip is mandatory and  may become a limiting factor in high performance designs. 
 The detection performance of  the moving-window detector is about 0.5 dB worse than the optimal detector which weights  the returned signals by the fourth power of the antenna voltage pattern.63 The angular loca-  tion of the target can be estimated from the output of this detector by taking the midpoint  between the first and last crossings of the detection threshold, or by taking the maximum value  of the running sum. After correcting for the bias, the accuracy of the location measurement is  only about 20 percent worse than the~retical.~~  Recirculating-delay-line integrat~r.~' -" The delay-line integrator, or moving-window detec-  tor, described above requires that a number of pulses, equal to that expected from the target,  be held in storage. A simplification can be had by recirculating the output through a single  delay line (Fig. 
 ,",  
 Results of TECs retrieved from different instruments are given in Table 3. The TEC deviation at 400 km is deﬁned as the absolute value of the difference between PALSAR VTEC and ISR VTEC. Since TEC varies in a PolSAR scene, we calculated the standard deviation of TEC for each PolSAR scene and present it following each term in parentheses. 
 BORNE 3!2 IMAGE USING  ACTIVE RADAR CALIBRATORS AND GROUND 
 Frequency agility. If the frequency of a pulse of length t is changed by at least 1/t, the echo  from uniformly distributed clutter will be decorrelated. Thus pulse-to-pulse frequency changes  (frequency .agility) of I /t or greater will decorrelate the clutter and permit an increase in  target-to-clutter ratio when the decorrelated pulses are integrated. 
 DOMAIN RADAR SYSTEMS USE A SAMPLING RECEIVER TO DOWN 
 Barton, Frequency Agility and Diversity , in Vol. 6 of Radars , Norwood, MA: Artech  House, 1977. ch09.indd   50 12/15/07   6:08:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Rajani     DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING   MALLA REDDY COLLEGE OF ENGINEERING & TECHNOLOGY   (Autonomous Institution – UGC, Govt. of India)    (Affiliated to JNTUH, Hyderabad, Approved by AICTE - Accredited by NBA & NAAC – ‘A’ Grade)  Maisammaguda, Dhulapally (Post Via. Kompally), Secunderabad – 500100, Telangana State, India  . 
 145-149. IEE (London) Conference Publi-  c;~tioti rlo. 155. 
 However, in many research applications, it remains advantageous for improved  data quality control purposes to access the full doppler spectrum and remove artifacts  prior to computing the spectral moments corresponding to the meteorological data  of interest.79,87 The wind profiling radar community has made extensive use of spec - tral processing for artifact removal and sensitivity improvement.88 One of the more  important tasks is estimating the noise floor so as to remove its effect on the spectral  moment estimates. Two objective techniques are common.89,90 Constantly improving  programmable digital signal processing chips and signal processing computers make  it possible for radar meteorologists to implement various types of spectrum process - ing techniques that vastly improve data quality over the simple pulse pair processing  algorithm. Furthermore, processors that adapt themselves to a variable environment in  which they usually operate are feasible. 
 If a = p = 1, no smoothing is included at all.  The classical a-fJ filter is designed to minimize the mean square error in the smoothed (filtered) . TRACKING RADAR 185  position and velocity, assuming small velocity changes between observations, or data samples. 
 Boltz’s Basic Radio or the Radio  Society of Great Britain’s Amateur Radio Handbook and  its supplement, and is familiar with normal circuit theory  and the use of the valve as a Class A, B, and C amplifier,  then some of the most important radar circuits will not  have a crossword-puzzle complexity.  The very names of typical radar circuits are often as  intriguing as the operation: we have already met such  strange additions to the English language as the ‘strobe’  and the ‘Cal.’ Now let us meet the ‘cathode follower,’  the ‘D.C. restorer,’ the ‘flip-flop,’ and the ‘multi-vib.’  We shall meet the ‘transitron fitp-flop’ and several other  circuits imported from American radar laboratories, but  first we must be introduced to the two firm friends which  run through all basic forms of radar pulse-shapers—the  differentiator and the integrator. 
 2008 ,46, 3076–3086. [ CrossRef ] ©2019 by the authors. Licensee MDPI, Basel, Switzerland. 
 Limiting in MTI radar.8·53-55 A limiter is usually employed in the IF amplifier just hcforc the  MT( processor to prevent the residue from large clutter echoes from saturating the display.  Ideally an MTI radar should reduce the clutter to a level comparable to rece.ivcr noise.  60  50  0)  "O  I ... 
 19.3 Signal spectra for semiactive homing indicate the clutter and feedthrough (spillover) with which the target signal must compete. Both fixed and moving illuminator cases are shown. The frequencies shown are for maximum clutter extent; i.e., all angles shown in Fig. 
 In  radar, the measurement error specified by Eq. ( 11.27) is that of the doppler frequency shift.  The value of a2 for a perfectly rectangular pulse of width r is 1t2r2/3; thus the rms  frequency error is  -./3 of -n:t(2E/N0)fi2 rectangular pulse ( 11.29)  The longer the pulse width, the better the accuracy of the frequency measurement. 
 83. Ref. 37, vol. 
 3.11, too little noise relative to the quantization increment of the A/D converter causes a loss in sensitivity; too much noise means a sacrifice of dynamic range. Samples of noise are taken at long range, often beyond the instrumented range of the radar (in dead time), to control the gain by means of a slow-reaction servo. If the radar has RF STC prior to any amplification, it can achieve meaningful dead time by switching in full attenuation; this minimizes external interference with minimal (and predictable) effect on system noise temperature. 
 D.C.)Rept8238,July28.1978. 97.Flad.E.H.:Tracking ofFormation FlyingAircraft. Illternational COl!ference RADAR-77, Oct.25-28, 1977.pr.160-163, lEE(London) Conference Publication No.155. 
 C. Jackson and J. Apel (deceased; the book is dedicated to him), Synthetic Aperture Radar Marine  User’s Manual , Washington, DC: Department of Commerce, National Oceanic and Atmospheric  Administration (NOAA), 2004. 
 The dissipated heat can be tolerated because the system operates at a low duty cycle. FIG. 5.15 AN/SPS-40 transmitter amplifier module. 
 Other waveforms are used in radar when particular objectives need to be achieved that cannot be accomplished with a pulse train. CW (a continuous sine wave) is employed on some specialized radars for the measurement of radial ve- locity from the doppler frequency shift. FM/CW (frequency-modulated CW) is used when range is to be measured with a CW waveform (Chap. 
 Griffiths: Video Integration in Radar and Sonar Systems, J. Brit. IRE,  vol. 
 ) ch22.indd   31 12/17/07   3:02:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 
 CRATE GRILLWORK OVER THE ENGINE INTAKES )NDEED  .ORTHROP DESIGNERS DEVISED HINGED COWLINGS THAT OPEN UP AT LANDING AND TAKEOFF SPEEDS TO INCREASE AIR 
 Thus, it is vitally  important to understand not only the structure of the ionosphere and the opportunities it  provides for propagation, but also the motions and disturbances that inhabit it. The variety of wave types and irregularity of production mechanisms in the ion - osphere is enormous, and includes not only those arising naturally but also many  induced phenomena such as those resulting from ground-based ionospheric RF heat - ers or rocket interactions with the ambient plasma. Among the most important from  the radar point of view are the following: • Transient plasma structures associated with ionized meteor trails; at any given loca - tion, meteors have a strong diurnal variation and directionality. 
 TPCII. J.. VOI. 
 POWER BEAMWIDTH ARE INDICATED BY . 
 China Inf. Sci. 2012 , 55, 1722–1754. 
 IAN FUNCTION  4HE GAUSSIAN FEED USED IN THIS SAMPLE ANALYSIS IS A HYPOTHETICAL FEED WITH A RADIALLY SYMMETRIC PATTERN AND VERY LOW SPILLOVER  AND MOST TYPICAL FEED HORN PATTERNS ARE WELL APPROXIMATED BY A GAUSSIAN FEED MODEL 4HE FEED SIZE DETERMINES THE EDGE TAPER  IE  THE LARGER THE FEED  THE GREATER THE EDGE TAPER 4HE PLOT IN &IGURE  SHOWS HOW THE THREE LOSS TERMS  AND THE TOTAL LOSS  VARY AS A FUNCTION OF FEED PATTERN EDGE TAPER  THAT IS  THE FEED POWER DIRECTED AT THE EDGE OF THE REFLECTOR  RELATIVE TO THE FEED PATTERN PEAK 4HIS IS USED  HERE BECAUSE THE FEED PATTERN I S MEASURED INDEPENDENT  OF THE REFLECTOR 7HEN THE EDGE TAPER IS LOW  VIRTUALLY ALL THE POWER STRIKES THE REFLECTOR AND THE LOSS IS INSIGNIFICANT !S TAPER DECREASES  THERE IS MORE SPILLOVER  AND FEED POWER MISSES THE REFLECTOR  INCREASING THE LOSS /N THE OTHER HAND  WITH TOO MUCH TAPER  THE TAPER EFFICIENCY IS POOR BECAUSE THE REFLECTOR IS UNDER ILLUMINATED &)'52%    #APACITIVE LOADING TO REDUCE FEED HORN BLOCKAGE.   2%&,%#4/2 !.4%..!3   £Ó° &IGURE  DEMONSTRATES THE GAIN OPTIMIZATION PROCESS WITH A HYPOTHETICAL FEED  PATTERN  BLOCKAGE  ETC  AND THE TOTAL LOSS IS  D"  EFFICIENCY  WHEN A  
 By far the most common of these is ground wave  or surface wave  propagation, which  is most effective for vertically polarized radiowaves traveling over highly conductive  surfaces such as seawater. In addition, there are applications for which line-of-sight  or spacewave propagation is appropriate, such as measurement of the HF RCS of  aerospace vehicles. Furthermore, in many instances, bistatic configurations can be  employed, with the possibility of using different propagation mechanisms for trans - mitter-target and target-receiver paths. 
 Bycombining theoutputbeamsofthenetworks withadditional circuitry, theButler beam-forming network canbemodified toobtainaperture illuminations thatresultinlower siJelobes thanavailable withuniform illumination. Thebeamwidth iswidened, thegain lowered, andthenetwork isnolongertheoretically lossless.Theaddition oftwoadjacent beamsofaButlerarray,withtheproperphasecorrection, resultsinanarraywithacosine illumination. Thecrossover islowerthanthelosslessnetwork, butthefirstsidelobe is-23dB insteadof-13.2dB. 
 17.4. This method isrestricted initsuse. The requirement ofacontinuous scan atanearly constant speed mentioned inSec. 
 Detailed descriptions ofthevarious radiators usedforarraysmaybefoundinthestandard textsonantennas andwillnotbediscussed here.Itshouldbecautioned, however, thatthe properties ofaradiating element inanarraycandiffersignificantly fromitsproperties whenin freespace.Forexample, theradiation resistance ofaninfinitely thin,half-wave dipoleinfree spaceis73ohms,butinaninfinitearraywithhalf-wavelength elementspacingandabackscreen ofquarter-wave separation itis153ohmswhenthebeamisbroadside. Theimpedance willalso varywithscanangle.Forafinitearraytheproperties varywithlocation oftheelement within thearray.Insomearrays,dummy elements areplacedontheperiphery soastoprovide the elements neartheedgewithanenvironment morelikethoselocatedintheinterior. Although therehavebeenmanydifferent kindsofradiators usedinphasedarrays,the dipole,theopen-ended waveguide, andtheslottedwaveguide probably havebeenemployed morethanothers.Inaddition totheconventional dipole,thedipolewithitsarmsbentback (likeanarrowhead) hasbeenusedforwide-angle coverage, thethickdipolehasbeenusedfor reducing mutualcoupling andforbroadbandwidth (adipolewithadirector rodalsoreduces mutualcoupling), crosseddipolesareemployed foroperation withdualorthogonal polariza­ tion.andprinted-circuit dipoles forsimplification offabrication. 
 Its properties reflect the balance between free electron production by the incident  solar radiation flux and free electron loss via various electron-ion and electron-neutral  recombination processes. Accordingly, the maximum ionization in the D region occurs  near the sub–solar point and will be greatest during periods of highest solar activity  (sunspot maximum), though it does not achieve densities sufficient to reflect or even  significantly refract HF radio waves. The key role of the D region in HF radiowave  propagation is signal attenuation via electron-neutral collisions that are frequent at  these moderate altitudes where the neutral species density is still relatively high. 
 RIZED IN 4ABLE  !TMOSPHERIC $UCTS  ! DUCT IS A CHANNEL IN WHICH ELECTROMAGNETIC ENERGY CAN  PROPAGATE OVER GREAT RANGES 4O PROPAGATE ENERGY WITHIN A DUCT  THE ANGLE MADE BY THE ELECTROMAGNETIC SYSTEMS ENERGY WITH THE DUCT MUST BE SMALL  USUALLY LESS THAN  4HICKER DUCTS  IN GENERAL  CAN SUPPORT TRAPPING FOR LOWER FREQUENCIES 4HE VERTICAL DISTRIBUTION OF REFRACTIVITY FOR A GIVEN SITUATION MUST BE CONSIDERED AS WELL AS THE GEO 
 Such inter- ference reduction iseffective only ifalarge deviation ratio isused, that is,ifthe ratio ofhalf the maximum carrier-frequency excursion tothe maximum modulation frequency islarge. (Adeviation ratio of4is considered excellent. )This requirement increases the necessary band- width ofthe r-fparts ofthe transmitter, and ofthe r-fand i-fstages of the receiver. 
 Pugh, and I. S. Reed, “Control loop noise in adaptive array antennas,” IEEE  Trans ., vol. 
 Although this is not an exact relation, it is a good enough approximation for  purposes of the present discussion. If the antenna beamwidth were 2" and if the scanning rate  were 36"/s (6 rpm), the spread in the spectrum of the received signal due to the finite time on  target would be equal to 18 Hz, independent of'the transmitted frequency.  In addition to the spread of the received signal spectrum caused by the finite time on  target, the spectrum may be further widened if the target cross section fluctuates. 
 Tlie dividing of the  freqlrcncy band into N independent parts by the N filters also allows a measure of the doppler  frequency to be made. Furtlierniore if moving clutter, such as from birds or weather, appears  at other-than-zero frequency, the threshold of each filter may be individually adjusted so as to  adapt to tlie clutter contained witllin it. This selectivity allows clutter to be removed wliicli  would be passed by a delay-line canceler. 
 STATE MODULATOR  WAS DEVELOPED AND  BEGAN TO BE USED FOR RADAR TRANSMITTERS AS EITHER CATHODE PULSED OR MODULATING ANODE PULSED MODULATORS  AS WELL AS GRID PULSED 3OLID 
 Record, vol. 2, pt. 1, pp. 
 Dohson: Radar Characteristics of Birds in Flight, Science. vol.  159. 
 The applied magnetic field is proportional to the current in the drive  wire which can be considered a solenoid with one turn. When a sufficiently large current is  passed through the drive wire threading the center of the toroid, the magnetization is driven to  saturation. When the current is reduced to zero, there exists a remanent magnetization B,. 
 HORIZON  BACKSCATTER (& RADAR v 2ADIO 3CIENCE  VOL   PP n    2 "ARNES  h!UTOMATED PROPAGATION ADVICE FOR /4(2 SHIP DETECTION v  )%% 0ROC 2ADAR  3ONAR   AND .AVIGATION  VOL   PP n  &EBRUARY   $ , ,UCAS  * , ,LOYD  * - (EADRICK  AND * & 4HOMASON  h#OMPUTER TECHNIQUES FOR PLANNING  AND MANAGEMENT OF /4( RADARS v .AVAL 2ES ,AB -EMO 2EPT   3EPTEMBER   * - (EADRICK  h(& OVER 
 IRE.  vol. 47, pp. 
 Analysis showsthatwhenthedriveoutputim­ pedancc issmall,theefTectoftemperature-caused variations intheincrement ofmagnetization willbesmall. Dual-mode ferritephaseshifters. Therearesomeapplications whichrequireareciprocal phase shifter.Asmentioned previously theRcggia-Spencer phaseshifterisreciprocal buthaslimita­ tiollssuch asslowswitching speed.temperature sensitivity, andanotparticularly goodfigurc cQ '0 ~ ~g.8,(I) ::> 8,(2) ----- --~ H' 3':Appliedmagnetic; H,field(H) 8,(3) -B,Figure8.12Hysteresis loopshowingthe principle offluxdrive.whereasingle ferritetoroidisexcited bydiscrete currentpulsestoproducedigitalphase­ shiftincrements fromwhatisbasically ananalogdevice.. 
 POLE FILTER   AND A THRESHOLD DECISION PROCESS  ! TARGET IS DECLARED WHEN THE INTEGRATED OUTPUT EXCEEDS TWO THRESHOLDS  &)'52%   "LOCK DIAGRAM OF CELL 
 $ AIRCRAFT FOLLOW 
 When  the transmitter of opportunity is from a broadcast station or communications link,  sources other than a radar, the bistatic radar has been called many things including  passive radar, passive bistatic radar, passive coherent location, parasitic radar, and  piggy-back radar.2 Transmitters-of-opportunity in military scenarios can be designated  either cooperative  or noncooperative , where cooperative denotes an allied or friendly  transmitter and noncooperative denotes a hostile or neutral transmitter . Bistatic target detection uses a process similar to that of a monostatic radar,  where the target is illuminated by a transmitter and target echoes are received,  detected, and processed by a receiver. When operating with transmitters using CW  or high-duty cycle waveforms, a bistatic receiver may need to augment its spa - tial isolation with spatial and/or spectral cancellation to reduce the transmitter’s  direct-path  feed-through to acceptable levels. 
 Russell and J. W. Wilson, “Radar-observed fine lines in the optically clear boundary layer:  reflectivity contributions from aerial plankton and its predators,” Boundary Layer Meteorol.,    vol. 
 7.7. If one wished to obtain relatively  uriifor~n illunlination across a paraboloid aperture with a feed of this type, only a small  angular portiori of tlie pattern sllould be used. An antenna with a large ratio of focal distance  to aritenna diameter would be necessary to achieve a relatively uniform illumination across the  aperture. 
 The bed of spikes in Fig. 11.13b is obtained with a periodic train of pulses. The interna 1  structure of each ~f the major components, illustrated figuratively by the simple arrows,  depends on the waveform of the individual pulses. 
 (Thelatter willbereferred tosimplyasmoriopulsc;) Whenthetargetisbeing tracked,the:signal-to-noi~e ratioavailable fromthemonopulse radarisgreaterthanthatofa;corlical;scan' radar,allotherthingsbeingequal,sincethe monopulse radarviewsthetarier~'fth~"peak ofitssumpatternwhiletheconical-scan radar viewsthetargetatanangleoffthe"peak oftheantenna beam.Thedifference insignal-to-noise ratiomightbefrom2to4dB.Forthesame'size aperture, thebeamwidth ofaconical-scan radarwillbeslightlygreaterthanthatofthemonopulse because itsfeedisoffsetfromthe focus. Thetracking accuracy ofamonopulse radarissuperior tothatoftheconical-scan radar becauseoftheabsenceoftargetamplitude-fluctuations andbecauseofitsgreatersignal-to­ noiseratio.Itisthepreferred technique forprecision tracking. However, bothmonopulse and conical-scan radarsaredegraded equallybythewandering oftheapparent position ofthe target(glint).. 
 4.34 for a tlirec-pulse delay-line ~anceler.~',~~ Tliere are two  basic methods for providing the doppler frequency compensation. In one implementation the  frequency of tlie coheretit oscillator (coho) is changed to compensate for the shift in the clutter  doppler frequency. This may be accomplished by mixing the output of the coho with a signal  from a tunable oscillator, the frequency of which is made equal to the clutter doppler. 
 Some of the ancillary requirements of an operational GPR system need to be con - sidered. Accurate, high-resolution, low-cost position referencing systems for use with  radar for subsurface survey techniques are now available. It is important that data can  be related to a true geographic reference particularly when filed on digital mapping  systems and used to define areas of safe working. 
 STAGE  SPATIAL NOISE CANCELLER WITH AN ADAPTIVE - 
 AP-24, pp. 896-899. November, 1976. 
 C  HT.  @ > 2  FIG. 2. 
 Thelattertermisdescriptive ofthefactthatthe velocityofpropagation, andtherefore thephase,ofasignalpropagated through awaveguide depends onthewidthoftheguide,orits"a"dimension. Thisphaseshiftingtechnique has beenusedforGCA(ground controlapproach) radarstomechanically scanfanbeamsin azimuth andelevation. Mechanically actuated phaseshiftersare,ofcourse,notcapable ofbeingactuated as rapidlyaselectronic devices,noraretheyasflexibleinbeingabletoselectanyrandom valueof phase.Itispossible, however, withseveralelectromechanical devicestoscanabeamoverits coverage atratesasfastas10timespersecond(0.1sswitching time),whichissufficiently rapid formanyapplications. 
 The large  attenuations are likely to limit millimeter radar to short-range applications where the total  attenuations are tolerable or to applications where the atmos'phere is absent, such as in space  or at very high altitudes. Millimeter wavelengths might also find application when the propa­ gation path does not traverse a large part of the earth's atmosphere, as when a ground-based  radar directs its energy at or near the zenith. (At 94 GHz the two-way loss in transiting  the entire atmosphere is about 1.7 dB at zenith, 3.5 dB at 60° from the zenith, and IO dB at 80°  from the zenith.)82  Submillimeter wavelengths.83·84 The advantages of high resolution, wide bandwidth, and  small antenna aperture are even more prevalent in the submillimcter proportion of the electro­ magnetic spectrum than at millimeters. 
 33. O'Neal, N. V., and P. 
 Eichel, D. C. Ghiglia, and P. 
 TURE  BUT UNLIKE THE ONE 
 ILY FOR BROADBAND COMMUNICATIONS LINKS  HAVE ENABLED #-2 MANUFACTURERS TO USE THESE IN THE RADAR TRANSMITTER TO REPLACE MAGNETRON 
 We shall use the term range resolution  to mean the resolu - tion along the line-of-sight (LOS) from the radar to the target region and crossrange  resolution  to mean the resolution along the direction perpendicular to the LOS and  parallel to the ground. The former is also frequently termed downrange resolution  to  emphasize that it is along the LOS. Crossrange resolution is also frequently called azi- muth resolution , since it is measured along a line obtained by holding range constant  and varying the azimuth (as measured from the physical antenna) of the LOS. 
 VERSION PROCESS &IGURE  SHOWS THE SPECTRAL MODIFICATIONS DUE TO THE SYSTEM RESPONSES  A  4HE  FIRST MODIFICATION ACCOUNTS FOR CORRELATION DUE TO THE RANGE TO THE CLUTTER OF INTEREST ;ASSUMED CLUTTER RANGE IS  y  NMI  KM  THUS  THE BREAK FREQUENCY IS  (Z=  B  3ECOND  A THREE 
 Because of its periodic nature, the filter also rejects energy  in the vicinity of the pulse repetition frequency and its harmonics.  The video signal [Eq. (4.3)] received from a particular target at a range R, is  V, = k sin (2nfdt - 4,) (4.4)  where 4o = phase shift and k = amplitude of video signal. 
 YEAR AND  MULTIYEAR SEA ICE 2ANGES ARE DETERMINED BY USING KNOWN VARIATIONS OF ICE CHARAC 
 AGILE RADAR v IN  )%% )NT  2ADAR #ONF  ,ONDON    PP n  ' 6 4RUNK  " ( #ANTRELL  AND & $ 1UEEN  h-ODIFIED GENERALIZED SIGN TEST PROCESSOR FOR  
 This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). 228. sensors Article An Improved Time-Series Model Considering Rheological Parameters for Surface Deformation Monitoring of Soft Clay Subgrade† Xuemin Xing1,2, Lifu Chen1,3,4,*, Zhihui Yuan1,3and Zhenning Shi2 1Laboratory of Radar Remote Sensing Applications, Changsha University of Science & Technology, Changsha 410014, China 2School of Traﬃc and Transportation Engineering, Changsha University of Science & Technology, Changsha 410014, China 3School of Electrical and Information Engineering, Changsha University of Science & Technology, Changsha 410014, China 4School of Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, UK *Correspondence: Lifu.Chen@newcastle.ac.uk †This paper is an expanded version of “Investigation on INSAR Time Series Deformation Model Considering Rheological Parameters for Soft Clay Subgrade Monitoring” published in the Proceedings of the ISPRS TC III Mid-term Symposium ‘Developments, Technologies and Applications in Remote Sensing’, Beijing, China,7–10 May 2018. 
 SYNTHETIC APERTURE RADAR  17 .196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 side cast by the sun. The portion of the Monument visible in the image is the north  side, illuminated by diffusely scattered sunlight. In comparison, the bottom illustration  in Figure 17.8 shows the geometry and result of SAR imagery, again with the shadow  on the north side. 
 Use of a four-port device is preferred as it presents a bet - ter matched load to the magnetron and, therefore, gives a cleaner RF spectrum. The  low-noise front-end  (LNFE) subsystem is connected to the circulator via a PIN diode  limiter, which protects the LNFE during pulse transmission. The modulator to the magnetron is typically a pulse forming network  (PFN), basi - cally comprised of capacitors and inductors. 
 The reason for this dependence  is that the relative phase of the individual echo signals is a function of the number of  wavelengths of change in relative range caused by the target’s random motion. Thus,  with shorter wavelengths, a given relative range change will subtend more wave - lengths, causing higher phase rate, resulting in higher-frequency noise components.  The rate of amplitude fluctuations of the envelope of the echo pulses is approximately  proportional to the radar frequency. 
 Schultz, F. V., et al.: Measurement of the Radar Cross-Section of a Man, Proc. IRE, vol. 
 Delayed Sweeps.—Any ofthe timing circuits just discussed can be used toprovide the trigger foradelayed, expanded sweep, and infact thk function canbecombined with that ofaccurate range determination. The most usual method using continuous delays isillustrated intheblock diagram ofFig. 13.39. 
 At tht! end of  the transmission of the radar pulse the receiver gain is made low so that large signals from  nearby clutter are attenuated. Echoes from nearby targets will also be attenuated; but because  of the inverse fourth-power variation of signal power with range, they will usually be large  enough to exceed the threshold and be detected. The receiver gain increases with time until  maximum sensitivity is obtained at ranges beyond which clutter echoes are expected. 
 Note that if P = 1 (no failed elements),  this equation becomes  MSSL2 =+=σ σ ησ ηφ A aT a N N2 2  This is the same as Eq. 13.22 except for ( )12−σT in the denominator, which is not  significant for low-sidelobe antennas. For the case in which the design sidelobes are  well below the sidelobes caused by errors, Allen has developed the set of curves shown  in Figure 13.19. 
 ALTITUDE TARGET TRACK 
 H., and E. M. Bradley: Some New Microwave Control Valves Employing the Negative  Glow Discharge. 
 The patterns of the spurious beams are of similar shape as  the original pattern but are displaced in angle and reduced in amplitude.  Random errors in reflectors. The cl&sical work on the effects of random errors on antenna  radiation patterns is due to Ruze.73.99.101 He pointed out that in a reflector antenna, only the  phase error in the aperture distribution need be considered. 
 In Proceedings of the 36th InternationalSymposium on Remote Sensing of Environment, Berlin, Germany, 11–15 May 2015; Schreier, G., Skrovseth, P .E., Staudenrausch, H., Eds.; Copernicus Gesellschaft Mbh: Gottingen, Germany, 2015; Volume 47, pp. 975–982. 14. 
 The original monopulse trackers suffered in antenna efficiency and complexity of microwave components since waveguide signal-combining circuitry was a relatively . new art. These problems were overcome, and monopulse radar with off-the-shelf components can readily outperform scanning and lobing systems. 
 The even divisor PRIs can be perturbed  iteratively by a small amount to achieve the desired visibility. The normalized target sig - nal-to-noise ratio, TP , varies dramatically with straddle and eclipsing losses (for example,  see Figure 5.18). The function to be optimized is a thresholded version of TPk or j.FIGURE 5.17  Medium-PRF central PRF selection example45 FIGURE 5.18  Example RGHPRF eclipsing and straddle near maximum range ch05.indd   19 12/17/07   1:26:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 M. Fernandez J. Vesecky, and C. 
 IEEE Nat. Radar Conf., pp. 230-234, Ann Arbor, Mich., Apr. 
 BANDWIDTH  PRODUCT     4HE LIMITED BANDWIDTH OF THE MAJORITY OF THE SCHEMES IMPLEMENTING %Q   AS  COMPARED WITH THE WIDEBAND OF A BARRAGE JAMMER THAT CAN BE REGARDED AS A CLUSTER  SPREAD IN ANGLE  OF NARROWBAND JAMMERS   1UADRATURE ERRORS IN SYNCHRONOUS IE  )  1  DETECTORS n. 
 TER PERFORMANCE BY DROPPING THE NEED FOR RACON COMPATIBILITY AT  '(Z  THEREBY ALLOWING OTHER FORMS OF MODULATION THAT WOULD ENABLE AFFORDABLE COHERENT PRO 
 ( 1. 7) shows the  range to be independent of ,t The correct relationship depends on whether it is assumed the  gain is constant or the effective area is constant with wavelength. Furthermore, the introduc­ tion of other constraints, such as the requirement to scan a specified volume in a given time,  can yield a different wavelength dependence. 
 If it is necessary to utilize  precisely the same waveform and RF pulse length from CPI to CPI, with, for example,  a klystron transmitter, the beam pulse of the klystron can be varied to maintain con - stant beam duty cycle while the RF pulse length is maintained constant. This wastes  part of the beam pulse energy for the longer PRIs, but the average power loading on  the power supply remains constant. The same technique can be utilized with solid- state devices by changing the drain voltage pulse duration, while holding the RF pulse  constant. 
 AESAs can accommodate up to 10% failures with very little degradation if properly  compensated in the BSC.24 From an MFAR point of view, the important parameters are volumetric densities  high enough to support less than 1/2 wavelength spacing; radiated power densities high  enough to support 4 watts per sq. cm.; radiated-to-prime-power efficiencies greater  than 25%; bandwidth of several GHz on transmit and almost twice that bandwidth on  receive; phase and amplitude calibration and control adequate to provide at least –50 dB  rms sidelobes; amplitude control adequate to provide 50 dB power management; noise  performance adequate to support the subclutter visibility requirements; and finally, suf - ficient storage and computing to allow beam repointing/adjustment in a fraction of  1 msec. Fast beam adjustment requires high-speed busses to each T/R channel. 
 DERIVATIVE COMPENSATION  AT THE RATE OF  D"DECADE (ENCE  FOR A GROUND 
 (2) inverse probability, (3) a suitably selected gating function preceded by a  ~natched filter, arid (4) the estimate of the variance using the likelihood function. The measure  of the error is the root mean square of the difference between the measured value and the true  value. The disturbance limiting the accuracy of the radar measurement is assumed to be the  receiver noise. 
 RANGE COVERAGE OF THE DEVICE  AND THE LOW COST OF REPRODUCI NG A GIVEN DESIGN 4HE  MAJOR SHORTCOMINGS OF THE 3!7 APPROACH ARE THAT THE WAVEFORM LENGTH IS RESTRICTED 3INCE SOUND TRAVELS ABOUT  TO  MM§S ON THE SURFACE OF A 3!7 DEVICE  A  MM QUARTZ DEVICE ABOUT THE LARGEST AVAILABLE   HAS A USABLE DELAY OF ABOUT  §S FOR A SINGLE PASS  !LSO  BECAUSE EACH 3!7 DEVICE IS WAVEFORM SPECIFIC  EACH WAVEFORM  REQUIRES A DIFFERENT DESIGN 3!7 PULSE COMPRESSION DEVICES DEPEND ON THE INTERDIGITAL TRANSDUCER FINGER LOCA 
 21.Fano,R.M.:Signal-to-noise Ratios inCorrelation Detectors, MITResearch Lab.Electronics Tech. Repr.186,Feb.19,1951. 22.George, S.F.:Effectiveness ofCrosscorrelation Detectors, Proc.NaIl.Electronics Conf.(Chicago), vol.10,pp.109-118, 1954. 
 The echo pulse is shown in Fig. 5.17a, the relative position of the gates at a particular  instant in Fig. 5.17b, and the error signal in Fig. 
 For large ground-based or ship - board phased arrays, factory calibration is usually performed using a planar near-field  antenna measurement facility.108,109 An attractive feature of the near-field range is that  the amplitude and phase of each element can be measured and a full hemispheric  antenna pattern can be generated. Near-field ranges are suitable for measuring low- sidelobe, high-gain antennas.110 Planar near-field antenna measurements are made by scanning a probe in a plane  parallel to the antenna under test and measuring the amplitude and phase at each probe  location. In rectangular coordinates, the probe position is given by ( x,y,z). 
 Rept. 114, June 1959. 19. 
 A precise focusing algorithm taking care of the Range Cells Migration Compensation is the goal of our future work. Recently, some authors have presented good results for SAR With Nonlinear FM Chirp Waveforms [ 21]. This speciﬁc case has not been addressed in this paper and will be the goal for future research. 
 13.42 ifaccurate range measurements aretobemade. Since only discrete sweep lengths are involved, the range-sweep flip-flop isswitched along with thesawtooth generator inorder toelimi- nate the vacuum tube otherwise required foranautomatic “turn-off” circuit. Since the amplitude ofthe sawtooth issmall compared tothe supply voltage, itissufficiently linear without special precautions. 
 W. G. Carrara, R. 
 (/2):/. 2!$!2   Óä°È£ THE FORM OF &IGURE  ON %ARTH BACKSCATTER ECHO POWER %STIMATES FOR NOISE POWER  SPECTRAL DENSITY ARE DERIVED FROM ##)2 2EPORT  
 SAR Image Change Detection Based on Correlation Kernel and Multistage Extreme Learning Machine. IEEE T rans. Geosci. 
 Theapplication ofthiscriterion toa reflector antenna requires themechanical tolerance ofthesurfacetobewithin±A/31.Itis possible, however, toobtainmoreprecisecriteriaforspecifying themaximum errorswhich maybetolerated intheaperture illumination. Systematic errors.The effe~tofsystematic errorsontheradiation patternmaybefoundby properly modifying theaperture distribution totakeaccount oftheknownerrors.Forexam­ ple,alinearphaseerroracrosstheantenna aperture causesthebeamposition totiltinangle.A quadratic, orsquare-law, variation inphaseisequivalent todefocusing theantenna. Aperiodic errorwithfundamental periodpIA,wherepismeasured inthesameunitsasisthewavelength .A,willproduce spurious beamsdisplaced atangles¢nfromtheorigin,according totherelation sin¢n=IIAlp,wherenisaninteger.Thepatterns ofthespurious beamsareofsimilarshapeas theoriginal patternbutaredisplaced inangleandreduced inamplitude. 
 It is  therefore not quite correct, in practical forms of H2S,  to think of the radiated energy as being strictly a ‘pencil’  of rays illuminating the ground. But sharp beaming in  this complicated pattern is necessary to ensure a de-  formed lobe of correct proportions, so that an aircraft  receives echoes back of approximately equal eaenees  from all targets within range.  This beam is rotated by the physical movement of the  scanner, with reflector and director, and in the earliest  systems the aerial itself is of the half-wave type, at the  focus of the scanner, and it illuminates a strip of the  ground at any one time, in the shape of a sector of a  circle not much more than 5 degrees wide. 
 Therefore, a radar provides the location of.the target as well as its presence. It can also provide  information about the type of target This is known as target classification.  The time delay between the transmission of the radar signal and the receipt of an echo is a  measure of the distance, or range, to the target. 
 Itindicates thatthermsphasevariation aboutthemeanphaseplanemustbelessthanA./14for aonedBlossofgain.Forshallow reflectors, thetwo-way pathofpropagation meansthatthe surfaceerrormustbeone-half thisamount, orA./28. Errorsdomorethanreducethepeakgainofanantenna. Theyaffecttheentirepattern. 
 869–899.  98. S. 
 NATING POLARIZATION MODE PROVIDES DUAL 
 LOOK CONDITION 4HE NARROW BEAM LIMITS THE FREQUENCY EXTENT OF THIS CLUTTER TO A RELATIVELY SMALL PORTION OF THE DOPPLER SPECTRUM 4HE REMAINDER OF THE ANTENNA PAT 
 If the doppler spectra of these two components are available, either through measurements or through predictions based on similar devices, the convolution of the two-way stalo spectrum (modified by the range-dependent effect) and the transmitter doppler spectrum provides an estimate of the spectrum of echoes from stable clutter, which is then modified by the two receiver filters and integrated to obtain the residue power caused by these two contributors. This power can be larger than the sum of the residues created by each contributor alone. These procedures are employed to diagnose the source of radar instability in an existing radar or to predict the performance of a radar in the design stage. 
 OF 
 ALLY INCORRECTLY CALLED TARGET IDENTIFICATION  4HE FIGHTER AND WINGMAN WILL COORDINATE MODES THROUGH THE NET SO THAT BOTH HAVE SITUATIONAL AWARENESS DURING THE LONG TIME SPAN REQUIRED TO PROVIDE TARGET RECOGNITION !NOTHER IMPORTANT FIGHTER CATEGORY IS WEAPON SUPPORT -ISSILE UPDATE IS THE MEA 
 PURPOSE PROCESSORS AND PLUG INTO A STANDARD BACKPLANE ARCHITECTURE  SUCH AS 6-% 4HIS CONFIGURATION OFFERS THE FLEXIBILITY OF SUP 
 These operations are usually performed using frequency-plane equivalent of cor- relation. $M 8(q ~x)dx = JF(CO) G(O)) exp (/«*) </o> (21.64) In other cases, such as polar format, Fourier transform operations are indicated and the use of the fast Fourier transform (FFT) plays an important role. Associated with FFT processing is the fact that algorithms exist for processing two-dimensional data with sampling points in the rectangular arrays, whereas the sample points obtained are equally spaced on radial lines. 
 It is widely used in SAR image analysis [ 19,20]. The scattering in different aspect angles is similar to the scattering in different polarization types. Therefore, we present aspect entropy as a descriptor of scattering anisotropy. 
 SIZE DISCRETES APPEAR WITH A LOWER DENSITY THAN THE SMALLER ONES  AND A MODEL COMMONLY ASSUMED AT THE HIGHER RADAR FREQUENCIES IS SHOWN IN 4ABLE  4HUS  AS A PRACTICAL MATTER    M DISCRETES ARE RARELY PRESENT   M ARE SOMETIMES PRESENT  AND   M ARE OFTEN PRESENT 4WO MECHANIZATIONS FOR DETECTING AND ELIMINATING FALSE REPORTS  FROM SIDELOBE DIS 
 Ifitisone tobeused inasystem with specially designed interrogator-responsors, certain discrete interrogation fre- quencies can beused aspart ofacode characterizing the particular beacon. PulseLength.—In order toavoid excess interrogation ofground beacons byairborne radars notinterested inbeacon replies, some beacons have been designed sothat they aretriggered only bypulses longer than those used for ordinary radar search. Careful design ofthe beacon receiver isrequired toprevent the stretching ofstrong, short pulses to give thesame effects aslonger ones ofmedium strength, but this problem has been solved satisfactorily. 
 Since the majority of human activity takes place  within the Earth’s atmosphere, the free-space propagation model is usually inadequate  for propagation assessment applications, and other propagation mechanisms need con - sideration. Under standard or normal atmospheric conditions, the radio ray curves  downward with a curvature less than the Earth’s surface. The effective-earth-radius  concept8 replaces the Earth’s true radius with a larger radius such that the relative  curvature between the ray and the Earth’s surface is maintained, and the ray becomes  a straight line. 
 WAVE CIRCUIT  AS IS USED IN THE 474  IS SUBSTITUTED FOR THE OUTPUT RESONANT CAVITY OF A KLYSTRON &IGURE D   THE BANDWIDTH OF THE KLYSTRON CAN BE INCREASED SIGNIFICANTLY  AND THERE IS A SLIGHT INCREASE IN EFFICIENCY 4HIS REQUIRES THAT THE INTERMEDIATE CAVITIES AND THE INPUT CAVITY OF SUCH A TUBE BE STAGGER 
 Note that the factor P,  can also be used to evaluate the effect of random thinning of array antennas.  For P, = I and srnall errors. the normalized pattern, obtained from Eq. 
 This form of integrator that sums the last n pulses is also known as the nroving-wirttlow  detector or the analog moving-window It, of course, can also be implemented In  digital circuitry. It is similar to the binary rnoving-window detector discussed above, but it  does not use a double threshold and it does not suppress the effects of large interference spikes  as does the binary detector. It does not suffer the 1.5 to 2 dB loss of the binary detector and ~t  can be employed to estimate the target's angle by beam splitting. 
 1970.  64. Begovich. 
 Figure 19.9 illustrates an air motion field obtained by two doppler radar observa - tions in an individual convective storm cell. Shown are the horizontal vector fields in  a plane approximately 100 m above the surface. The phenomenon being measured is  a low-level divergent outflow (or microburst) just to right of the center. 
 One of the most important of the variable-index-of-refraction lenses in the field of radar is  that due to Luneburg.53 The Luneburg lens is spherically symmetric and has the property that  a plane wave incident on the sphere is focused to a point on the surface al the diametrically  opposite side. Likewise, a transmitting point source on the surface of the sphere is converted to  a plane wave on passing through the Jens (Fig. 7.21 ). 
       #          '&*)(          
            
 Atypical setisH,I,G, and B.Histhemagnetic field, 1istheanode current, and Gand Bare thereal and theimaginary parts ofther-fload onthe magnetron meas- ured atsome arbitrary point inthe output line. The observed quanti- ties are three innumber, usually power P,wavelength A,and voltage V. The problem ofpresenting these observed quantities interms ofthe four parameters isgreatly simplified bythe fact that the input and output parameters operate nearly independently ofone another. 
 Brown, W. M .. and R. 
 LATITUDE WESTERLY WINDS  AND EQUATORWARD LAY THE TROPICAL EASTERLIES OR THE TRADE WINDS 7ITHIN THESE HIGH 
 Ramsey, J. F., and J. A. 
 46-49.  59. McLoughlan, S. 
 TICAL ORBIT CONSTRAINT ATTRACTED MORE THAN A LITTLE ATTENTION FROM THE 3!2 DESIGN TEAM 4HE -AGELLAN RADAR HAD TO ADAPT TO VARIATIONS IN RELATIVE ALTITUDE FROM APPROXIMATELY   KM NEAR THE EQUATOR  TO MORE THAN  KM OVER THE POLES  1UITE REASONABLY ONE MIGHT EXPECT THAT THE RESULTING IMAGERYLET ALONE THE IMPLIED TIMING AND SCAL 
 LAW  OR LOGARITHMIC DETECTOR 4HE LOSS IN DETECTABILITY DUE TO THE CLUTTER MAP IS ANALOGOUS TO THE #&!2 LOSS ANA 
 The techniques described previously for  reducing leakage in the CW radar apply equally well to the FM-CW radar. Separate antennas  and direct cancellation of the leakage signal are two techniques which give considerable  isolation.  Sinusoidal modulation. 
 IEEE Access 2018 ,6, 34296–34306. [ CrossRef ] 261. Sensors 2019 ,19, 346 14. 
 At the higher frequencies where the lobes are narrow, a count of the lobes per unit  distance can he related to the target height. Although the technique of lobe rrcognition is  relatively ·simple and has been reported to have been used in World War Jl,45 its poor  reliability, low target capacity, and poor accuracy, make it unattractive.  Time-difference height finding. 
 It is  powihle in a lens array to reduce rhe riunlber of phase shifters by "thinning" the number of  output radiators. 7'his is acconlplished by combining pairs of input elements and feeding the  out put of each pair to a single-phase shifter and radiating element. The thinned elements are  near the outer portion of the antenna rather than at the center so as to produce a density taper  (Sec. 
 326 3.'7. May. 1975. 
 Holiday, G. St-Cyr, and N. E. 
 Ravazzi, C.; Fosson, S.; Magli, E. Distributed Iterative Thresholding for /lscript0//lscript1-Regularized Linear Inverse Problems. IEEE T rans. 
 Inonedesign,anX-bandpassivereceiver protector wascapableoflimiting aInsrisetime, multi-kilowatt RFpulsestol-Wspikelevels.53. In many radar systems the STC (sensitivity time control), which is a time-dependent  attenuator, is placed in the RF portion of the radar receiver rather than in the IF. When a  diode limiter is used in the receiver protector, the STC function can be readily incorporated by  inserting a variable bias into the limiter diodes to provide an attenuator that varies with  time.40*49 The PIN diodes serve the dual function of self-limiting during transmit, and act as a  variable attenuator, or STC, during receive. 
 Whereas the previously discussed polyphase codes are  derived from LFM waveforms, P(n, k) codes are derived from step approximations of  the phase characteristic of the weighting function of NLFM waveforms.20 The weight - ing function is given by   W f k kf Bn( ) ( ) cos = + −   1π (8.21) where k and n are parameters of the weighting function, B is the swept bandwidth of  the waveform, and – B/2 ≤ f ≤ B/2. This is a cosn weighting on a pedestal of height k  (Figure 8.21). Hamming weighting is achieved for n = 2 and k = 0.08.Polyphase  Code Phase Phase vs. 
 STAGE LATTICE PREDICTOR  -     AS THE FIRST STAGE AND AN  ADAPTIVE TAPPED DELAY LINE AS THE SECOND STAGE  WHICH ACHIEVED ^ D" CANCELLATION OF THE NARROW 
 It should be apparent that the total reflected wave in any element . FIG. 7.14 Scanned mismatch variation for different element spacings (h/\ is the dipole spacing above a ground plane). 
 Losses (L): The loss term contains the two-way losses along the path tra- versed including ionospheric absorption and ground-reflection losses as well as any radar system losses. Ionospheric losses, while predicted on a statistical ba- sis, constitute a major unknown in real-time radar operation. 8. 
 BASED SYSTEMS  )!,! EXPECTS A  TARGET TRACK CAPABILITY AND A PLOT EXTRACTOR THAT CAN DEAL WITH MORE THAN   PLOTS PER ROTATION /N AN ADVANCED SYSTEM  MORE THAT  TARGETS MAY HAVE TO BE TRACKED WITH A POSSIBILITY OF MORE THAN   PLOTS PER ANTENNA REVOLUTION ** 
 (10.27) are absorbed in the constant k. An a posteriori  receiver, if it could be built, is one whose output is given by the above equation. If the receiver  output (the a posteriori probability) is greater than a predetermined threshold, a target is said  to be present. 
 Some radars use circular polarization in order to detect aircraftlike targets in rain. In that case, the direction of the E field varies with time at any fixed obser- vation point, tracing a circular locus once per RF cycle in a fixed plane normal to the direction of propagation. Two senses of circular polarization (CP) are possi- ble, right-hand (RHCP) and left-hand (LHCP). 
 Examples. Klystrons have seen wide application in radar. Several examples of radar pulse  klystrons will be briefly mentioned. 
 2.9) respectively. Inany case, thewidth ofaninterference lobe will beless than the width ofthe primary radi- _&=,,,/,ation pattern since MIwill certainly begreater than thevertical aperture _~ ofthe antenna. A------ ‘- A,/4hl Asthe geometry ofthe problem------ isnot altered ifwe interchange I:IG. 
 (Photograph courtesy of General Elec- tric Company.} . FPS-117. The AN/FPS-117 radars are operational for the U.S. 
 Atagiven moment, there may bemore than ahundred individual targets, for each ofwhich the radar must provide sufficiently accurate positional information toenable controllers toissue prompt instructions topilots. Radar equipments suitable forsuch different purposes will present wide differences indesign. This chapter and the next deal with the principal fundamental differences that appear invarious conventional pulse radar designs. 
 ThetermBraggsdtterissometimes usedtodescribe thisformofscatlcnng. by analogy totheBragg-scatte..- modefortheX-raydiffraction bycrystals. Thevelocity ofawaterwave(agravitywaveindeepwater)isv=(gAw/2n)JI2,where9is theacceleration ofgravity. 
 (Courtesy Westinghouse Electric Corporation.)FEEDSURFACE COLLIMATION POINTSRADIATORS PHASESHIFTERS . (a) (b) FIG. 6.19 Monopulse antennas, (a) Phase, (b) Amplitude. 
 615] PRECISION TRACKING DURING RAPID SCAN 211 splashes ofshells that miss thetarget canbeseen onthescope oftheradar. Accurate “spotting-in” offireboth inrange and indeflection ispossible with this type ofset. The antenna and scanning principle ofthe AN/TPG-l (which was also designated, invarious modifications, asSCR-598, AhT/MPG-l, .lN/FPG-1) aredescribed inSec. 
 BASED PARAMETERS 4HEREFORE  THE TIMELINE DEFINITIONS USED THROUGHOUT THIS CHAPTER ARE DEFINED HERE &IGURE  ILLUSTRATES THE DIFFERENT TIME SCALES 3TARTING AT THE LOWEST LEVEL  A SERIES  OF COHERENT PULSES ARE TRANSMITTED AT A PULSE REPETITION FREQUENCY 02&  4HE TIME BETWEEN THE PULSES IS THE  INTERPULSE PERIOD )00   WHICH IS SIMPLY THE INVERSE OF THE  02& 4HE RECEIVE PORTION OF THE )00 IS BROKEN UP INTO RANGE GATES 4HE  TRANSMIT DUTY  CYCLE IS THE TRANSMIT PULSE WIDTH DIVIDED BY THE )00 4HE TRAIN OF PULSES IS CALLED THE COHERENT PROCESSING INTERVAL #0)  4HE COHERENT PROCESSING FORMS A BANK OF DOPPLER  &)'52%  %XAMPLE OF RANGE GATES WITH  OVERLAP EQUALLY SPACED IN THE INTERPULSE PERIOD   SB REPRESENTS THE EXTRA BLANKING TIME AFTER THE TRANSMIT PULSE TO ALLOW FOR RECEIVERPROTECTOR RECOVERY  
 SANDWICH IS A FIVE 
 BAND DATA WITHIN o D" . £x°£Ó  2!$!2 (!.$"//+  ALL THESE MEASUREMENTS WERE MADE OVER FULLY DEVELOPED SEAS  IT IS CLEAR THAT THERE IS  A RATHER STRONG CONSISTENCY AMONG THEM  WHICH REINFORCES THE OBSERVATION MADE IN REFERENCE TO &IGURE  THAT THE FREQUENCY DEPENDENCE OF SEA CLUTTER AT INTERMEDIATE GRAZING ANGLES IS WEAK AT MICROWAVE FREQUENCIES FROM , TO + BAND $ E P E N D E N C E  O N  7 I N D  3 P E E D  A N D  $ I R E C T I O N    %XPERIMENTALLY  THE RELATION  BETWEEN SEA CLUTTER AND WIND SPEED IS COMPLEX AND UNCERTAIN  IT HAVING BEEN FOUND TO DEPEND ON ALMOST ALL OF THE PARAMETERS THAT CHARACTERIZE SEA CLUTTER FREQUENCY  GRAZING ANGLE  POLARIZATION  THE STATE OF THE SEA SURFACE  THE DIRECTION AND SPEED OF THE WIND ITSELF  AND EVEN ON WHETHER THE MEASUREMENTS ARE MADE FROM AN AIRCRAFT OR A TOWER PLATFORM  ! COMMON WAY TO ORGANIZE CLUTTER DATA IS TO SEEK THE BEST STRAIGHT 
 204 THEGATHERING ANDPRESENTATION OFRADAR DATA [SEC. 614. SEC. 
 ING THE USE OF AN OFFSET FEED &IGURE  C  4HE FEED IS STILL GENERALLY LOCATED AT THE  FOCAL POINT  BUT THE REFLECTOR IS REALIZED VIA USE OF A DIFFERENT PORTION OF THE PARABOLA &OR OFFSET 
 Four radar look directions with respect to the given current ﬁeld. The red arrows represent the four radar look directions. The xaxis of the current ﬁeld and wind direction are indicated by black arrows. 
 Antennas mounted on aircraft must also be housed within a radome  to offer protection from large aerodynamic loads and to avoid disturbance to the control of the  aircraft and minimize drag.  The design of radomes for antennas may be divided into two separate and relatively  distinct classes, depending upon whether the antenna is for airborne or ground-based (or  ship-based) application. The airborne ra'dome is characterized by smaller size than ground-  based radomes since the antennas that can be carried in an aircraft are generally smaller. 
 Doviak and Zrnic ´23 place special emphasis on  doppler aspects of meteorological radar, whereas Bringi and Chandra24 emphasize all  aspects of polarimetric radars and Lhermitte25 focuses on millimeter wave (cloud) radars.  Rinehart’s Radar for Meteorologists26 gives a broad and easily comprehendible over - view of all aspects of weather radar. The IEEE Geoscience and Electronics Special Issue  on Radar Meteorology,27 Atlas’s Radar in Meteorology,21 Wakimoto and Srivastiva’s  Radar and Atmospheric Science:  A Collection of Essays in Honor of David Atlas,28 and  ch19.indd   2 12/20/07   5:37:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 IEEE, vol. 61,  pp. 143 · 144. 
 Peak Loss/dB PSLR/dB ISLR/dB Spectral Index 2 3 4 5 2 3 4 5 2 3 4 5 Sliding spotlight 6.81 7.95 8.88 10.84 −4.77−3.21−2.33−1.67−1.35−1.04 0.61 2.33 Stripmap 2.08 4.41 6.20 7.87 −6.57−4.39−2.76−1.99−3.96−2.73−0.45 0.36 6. Conclusions The space-borne P-band SAR system has a splendid prospect for its advantage in penetration ability. However, the P-band SAR imaging resolution is limited for its low central frequency and sensitivity of the ionospheric effect. 
 Remote. Sens. 2016 ,54, 4023–4038. 
 &  $ETECTION OF ALL TARGETS IS DIFFICULT WHEN THIS EFFECT OCCURS u 4HE AURORAE ARE DYNAMIC STRUCTURES GOVERNED BY FIELDS AND PLASMA FLOWS IN THE MAG 
 Ê, ,Ê­-,® )N ITS MOST GENERAL FORM  AN IMAGING RADAR IS A DEVICE DESIGNED TO PROVIDE A TWO 
 YEAR SOLAR CYCLE  SEASONAL CHANGES  AND THE DIURNAL CYCLE OF THE % 
 29.Taylor,S.A.,andJ.L.MacArthur: DigitalPulseCompression RadarReceiver, APLTechnical Digest. vol.6.pp.2-10.March/April, 1967. ,. 
 (editorial article), October-November-December 1976. 25. AN/FPS-117 Minimally Attended Solid State Radar System, brochure, General Electric Company. 
 It is more attractive for application at the higher microwave  frequencies where the available bandwidths are large and the normal MTI suffers from exces­ sive blind speeds.  REFERENCES  1. Ridenour, L. 
 For exam - ple, if operating at an average RF frequency of 1300 MHz, at an average PRF of  1400 Hz (ambiguous velocity of 312 knots), and covering a velocity range of interest  of ±2500 knots, there are approximately 16 doppler ambiguities to cover. Using the  factors of –3, 2, –1, 3, as used in PRF stagger selection, the interpulse periods of the  four different PRFs would be in the ratio of 13, 18, 15, 19. The average of these ratios  is 16.25. 
 There are applications where it is not possible or convenient to use the  conventional CRT display that requires a darkened environment; such as in the cockpit of an  aircraft or an airfield control tower. One form of bright display is the direct-view storage  t~ihe." It riot otily operates under ambient light conditions, but it can provide a variable  persistence. In this device, neither the brightness nor the persistence is directly affected by the  short duration of the video signal, or by the characteristic of the viewing-screen phosphor. 
 ING OR VELOCITY 
     WHERE M IS THE COMPLEX INDEX OF REFRACTION  !T TEMPERATURES BETWEEN   AND n# AND  CENTIMETER WAVELENGTHS  \+\ y  FOR THE WATER PHASE AND \ +\ y  FOR THE ICE  PHASE %QUATION  CAN NOW BE WRITTEN AS   HP L   £  \\+$I I. 
 IEE, vol. 133, pt. F, pp. 
 W.: "Radar Reflectivity of Land and Sea," Lexington Books, D. C. Heath and Co.,  Lexington, Mass., 1975. 
 Diffraction is the process  by which the direction of propagating radiation is changed so that it spreads into the  geometric shadow region of an opaque object that lies in the radiation field. In the  earth-atmosphere system, diffraction occurs where the straight-line distance between  the transmitter and receiver is just tangent to the Earth’s surface. For a homogeneous  atmosphere, this point of tangency with the Earth is referred to as the geometrical   horizon. 
 As the target moves, the range gates automat­ ically follow. The range-gate stealer operates by initially transmitting a single pulse in synchro­ nism with each pulse received from the radar, thereby strengthening the target echo. The  repeater slowly shifts the timing of its own pulse transmissions to cause an apparent change in  the target range. 
 Ó{°xä  2!$!2 (!.$"//+  u 3POT JAMMER )T ALSO COVERS THE ENTIRE SWATH AND WITH UNIFORM INTENSITY DISTURBING  NOISE AS FOR THE BARRAGE JAMMER HOWEVER  ITS IMAGE WILL DIFFER FROM THE BARRAGE NOISE BECAUSE THE &OURIER TRANSFORM OF NARROWER BAND JAMMER NOISE WILL RESULT IN SPECKLE SIZE IN THE RANGE DIMENSION THAT IS LARGER THAN THAT OF THERMAL NOISE OR CLUTTER 4HE PROCESSED CROSS 
 feed pattern   edge taper ch12.indd   9 12/17/07   2:31:11 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 
 33-36, 39, December, 1973.  9. Dodds, W. 
 78-82, 1980. 53. Auterman, J. 
 This “burst” of air spreads out radially as it strikes the ground, forming a ring of  diverging53air about 0.3 to 1 km deep and of the order of 2 to 4 km in diameter with  divergent winds greater than 10 m/s and lasting less than 20 minutes. Aircraft pen - etrating a microburst first experience an increase in head wind and then a continu - ous, performance-robbing decrease in head wind, which can cause the plane to crash  if encountered shortly before touchdown or just as the aircraft is taking off. More  complete descriptions of microbursts and their effects on aviation safety are given by  Fujita140,141 and McCarthy and Serafin.142 FIGURE   19. 
 AP-I I. pp. 786-788. 
 DANT .OMINAL 02& IS  (Z  o  (Z $ATA RATES SPAN  -BITSS TO  -BITSS   DEPENDING ON MODE 4HE ON 
 The higher" tails" of the probability density function of non-Rayleigh  clutter mean that there will be a greater number of false alarms in the conventional receiver  designed on the basis of Rayleigh statistics. The false alarms with non-Rayleigh clutter can be  reduced to any desired level by raising the receiver threshold. Raising the threshold, however,  can require a significantly larger signal-to-noise, or signal-to-i;:lutter, ratio for a given proba­ bility or detection. 
 ( b) Image of tractor-trailer truck using “keystone” processing; the truck’s cab is  at the bottom and the trailer is above it. ( after R. P . 
 P. Zehner, “Bistatic radar cross section of ship targets,” IEEE J. Ocean. 
 CONTROL VACUUM TUBE WAS USED TO GOOD ADVANTAGE FOR A LONG TIME IN 5(& AND LOWER FREQUENCY RADARS  BUT THERE HAS BEEN LESS INTEREST IN THE LOWER FREQUENCIES FOR RADAR !LTHOUGH NOT EVERYONE MIGHT AGREE  SOME RADAR SYSTEM ENGINEERSIF GIVEN A  CHOICEWOULD CONSIDER THE KLYSTRON AMPLIFIER AS THE PRIME CANDI DATE FOR A HIGH 
 $ AIRBORNE EARLY 
 tilt. 102 INTRODUCTION TO RADAR SYSTEMS  Description of operation. A simple CW radar such as was described in Sec. 
 2.8 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 PRFs on successive coherent dwells will cause the target response to fall at different  frequencies of the filter passband on the successive opportunities during the time on  target, thus eliminating blind speeds. Each doppler filter is designed to respond to targets in nonoverlapping portions  of the doppler frequency band and to suppress sources of clutter at all other doppler  frequencies. This approach maximizes the coherent signal integration in each doppler  filter and provides clutter attenuation over a larger range of doppler frequencies than  achievable with a single MTI filter. 
 FADING  TARGETS  TRACK 
    &)'52%     3HIFT 
 (The actual number, of course, varies considerably with tube type and application.)  There are two basic radar-transmitter configurations. One is the self-excited oscillator,  exemplified by the magnetron. The other is the power amplifier, which utilizes a low power,  stable oscillator whose output is raised to the required power level by one or more amplifiei  stages. 
 The helical scan thus produced covers anelevation interval of25°. The. 202 THEGATHERING ANDPRESENTATION OFRADAR DATA [SEC. 
 381-392, 1985. 6. Hall, M. 
 The am- plitude levels in Fig. 24.27 are given in decibels relative to an arbitrary reference. Figure 24.27« gives a short time history of received power amplitude versus doppler frequency in one range gate. 
 Photo-Oplicnl Instr~rmerrtution  engineer.^, vol. 128, "Effective UIilization of Optics in  Radar Systems." pp. 128-143. 
 TIONS 3OME CHANNELS IN THE ARRAY ARE DEDICATED TO OTHER FUNCTI ONS SUCH AS CALIBRATION   JAMMER NULLING  SIDELOBE BLANKING  CLOSE IN MISSILE DATALINK  OUT 
 TRIBUTED SCENE 4HERE IS NO NEED FOR A KNOWN POINT 
 B. Crawford, and W. W. 
 At the beginning of WWII, Germany had progressed further in radar development and employed radar units on the ground and in the air fordefense against allied aircraft. The ability of radar to serve as an earlywarning device proved valuable as a defensive tool for the British and theGermans. Although radar was employed at the start of the war as a defensive weapon,asthewarprogressed,itcametobeusedforoffensivepurposestoo.By the middle of 1941 radar had been employed to track aircraftautomatically in azimuth and elevation and later to track targetsautomatically in range. 
 BEAM WIDTH AND CONTROL OF COVERAGE AND SCAN ARE VALUABLE AND WORTHWHILE %##- FEATURES OF ALL RADARS )F AN AIR DEFENSE RADAR OPERATES IN A SEVERE %#- ENVIRONMENT  THE DETECTION RANGE  CAN BE DEGRADED BECAUSE OF JAMMING ENTERING THE SIDELOBES /N TRANSMIT  THE ENERGY RADIATED INTO SPATIAL REGIONS OUTSIDE OF THE MAIN BEAM IS SUBJECT TO BEING RECEIVED BY ENEMY 272S OR !2-S &OR THESE REASONS  LOW SIDELOBES ARE DESIRABLE ON BOTH RECEIVE AND TRANSMIT SEE 3CHRANK   0ATTON  AND #HAPTER  IN &ARINA  3OMETIMES  THE INCREASE IN MAIN 
 NOISE POWER IS THE THERMAL 
          
 7 .56  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 44. S. Blackman and R. 
 A., et al, "Waveform Design and Doppler Sensitivity Analysis for Nonlinear FM Chirp Pulses", IEE Proceedings, vol.133, Pt. F, No.2, pp.163 - 175,April 1986.  . 
 3.4 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 techniques such as time-averaged-clutter coherent airborne radar (TACCAR). This  technique attempts to center the largest return from main-beam clutter at zero doppler  frequency such that a simple MTI filter, also centered at zero doppler frequency, will  cancel the main-beam clutter. As shown in Figure 3.3, the apparent radial velocity of the clutter is Vr = −Vg cos a,  where Vg is the ground speed of the platform and α is the angle subtended between the line- of-sight to a point on the Earth’s surface and the aircraft’s velocity vector. 
 Trial Report No. 44/74, 12th November 1944 (TNA AIR 65/144) [10] ASV Mk. VIA Wellington XIV Aircraft (First Report), ASWDU Report 45/5, March 1945 (TNA AIR 65/164) [11] ASV Mk. 
 Ament.W.S.:Toward aTheoryofReflection byaRoughSurface, Proc.IRE,vol.41,pp.142146, Jant/ary. 195.1. Beard.C.I..I.Kat?andLM.Spetner: Phenomenological VectorModelofMicrowave Reflection fromtheOcean,IRETrans.,vol.AP-4,pp.162-167, April,1956. 
 The pulse-width determines the actual length  of time which the transmitter is switched on at each pulse  —in other words, the duration of our short, sharp shout.  The degree of recurrence of the pulses is known as the  “pulse recurrence frequency,’ or PRF, and, of course,  it 1s really the number of shouts we give each second.  All this is controlled by Mod circuits, in which by  vatying condenser and resistance values we arrange to  produce the right shape of pulse, for the desired period  of time (pulse-width), and the necessary number of  times per second—the PRF. 
 Licitra, Millimeter Radar for Low-Angle Tracking. IEEE  EASCON '74 Record, pp. 72-75, IEEE Publication 74 CHO 883-1 AES. 
 Blake, L. V.: Prediction of Radar Range, chap. 2 of" Radar Handbook," M. 
 R. French, Space Vehicle Design , American Institute of Aeronautics and  Astronautics, 2004.  4. 
 Whenm=I,the chi-square distribution ofEq.(2.40)reducestotheexponential, orRayleigh-power, distribu­ tionofEq.(2.39a)thatappliestoSwerling cases1and2.Cases3and4,described byEq.(2.39b), areequivalent tom=2inthechi-square distribution. Theratioofthevariance totheaverage valueofthecrosssectionisequaltom-1/2forthechi-square distribution. Thelargerthevalue ofm,themoreconstrained willbethefluctuations. 
 PULSE AND HIGH 
 'Tlie ~iiulti-  pat11 crror can he quite severe and make tile angle measurement in many cases almost useless,  as discilsscd in Scc. 22.3 of Kcf. 32. 
 Jelffs: Design of MTI Filters with Staggered PRF: A  Pole-Zero Approacli, Ptm. IEE, vol. 121, pp. 
 Unlike a conven - tional antenna, where mismatch affects only the level of the power radiated and not the  shape of the pattern, spurious lobes in the scanning array may appear as a consequence  of the mismatch. Further, there are conditions where an antenna that is well matched at  broadside may have some angle of scan at which most of the power is reflected. The variation in element impedance and element pattern is a manifestation of the  mutual coupling between radiating elements that are in close proximity to one another. 
 Such an occurrence is called afalse alarm. Therefore, if the threshold is set too  low, false target indications are obtained, but if it is set too high, targets might be missed. The  selection of the proper threshold level is a compromise that depends upon how important it is  if a mistake is made either by (1) failing to recognize a signal that is present (probability of z  miss) or by (2) falsely indicating the presence of a signal when none exists (probability of a false  alarm). 
 7) and a  separate chapter covers the phased-array antenna (Chap. 8). Devoting a single chapter to the  array antenria is inore a reflection of interest rather than recognition of extensive application. 
 PURPOSE INSTRUMENTATION RADARS AND MODIFIED STANDARD RADARS MAY BE USED TO  DETERMINE THE GROUND RETURN 3INCE THE GROUND RETURN IS ALMOST INVARIABLY DUE TO SCATTER 
    %3!   # 66 * 
 188 INTRODUCTION TO RADAR SYSTEMS  41. Barton, D. K., and H. 
 Onthe whole, the microwave equipment is considerably superior totheothers because ofitscompactness, thesmall power involved, the narrowness ofthe beam, and the greater freedom from interference. However, thefact that theuseoffrequency modula- tion didnot permit thepulses tobetransmitted athigher level than the video signals was adefinite handicap forreasons described below. The equipment asawhole operated about asanticipated. 
 Finally, the effect of the radome must be considered. Because of aerodynamic considerations, the radome enclosing the gimballed antenna will be pointed rather than a hemisphere. Thus, at different gimbal (look) angles the radar signal will pass through a different portion of the radome, and the apparent LOS to the tar- get will change with gimbal angle because of refraction (aberration). 
 Subsequently a three-site fence  in South Texas was deployed to evaluate the use of bistatic range measurements to  improve location accuracy,55 but it never entered continuous operation.FIGURE 23.4.  Real-time data flow in a NAVSPASUR receiving station. “ Transmitter  energy reflected by the satellite is received by various collinear arrays of dipoles at  the receiver station… [Signals] from four in-line arrays feeds the alert receiver which  detects the presence of radio energy in excess of preset threshold levels. 
 This we prevent by making the end and walls of  . 1 ON THE SCREEN 65  the tube slightly conducting; a thin deposit of graphite  is the usual solution to surface accumulation.  Lateral attraction or repulsion caused by voltages  applied to the tubes, slotted discs, and other electrode  shapes inside the CRT cause the beam to be speeded up,  thinned down, and generally brought as nearly as pos-  sible like a pencil, so that it may impinge on the screen  end and cause fluorescence over an area probably not  more than a + mm. 
 IEEE,  vol. 51, pp. 1016-1027, July, 1963. 
 3H. Kat7. I.. 
 Attenuation ofthereceived signals atboth frequencies must beheld toasmall amount. Inany case, itisdesirable toinclude some device that will automati- cally keep the local oscillator forbeacon signals intune. When the beacon receiver iscompletely separate from the radar receiver, itis advantageous toprovide switching arrangements sothat the radar operator can have hischoice ofeither radar orbeacon signals alone, or both together. 
 STATE TRANSMITTER AS PART OF A NEW SYSTEM THAN IT IS TO RETROFIT ONE INTO AN OLD SYSTEM THAT USUALLY DOES NOT HAVE ALL THESE FEATURES. ££°{  2!$!2 (!.$"//+  4HE USE OF SOLID 
 19.)  62. Elphick, B. L., M. 
 -Ê"Ê / 
 VIEWING   #ONTINUED  . £n°n  2!$!2 (!.$"//+  ANALOG  -(Z  OFFSET VIDEO   TO BE CONVERTED ON THE GROUND TO EITHER OPTICAL MEDIA  TRANSPARENT FILM STRIPS  OR DIGITIZED  
 81. Strauch, R. G., B. 
 4HIERRY  % 4HOUVENOT  . 3TEUNOU  # -AVROCORDATOS   AND 2 &RANCIS  h/VERVIEW OF THE PERFORMANCES AND TRACKING DESIGN OF THE 3)2!, ALTIMETER FOR THE #RYO3AT MISSION v IN  0ROCEEDINGS )%%% )NTERNATIONAL 'EOSCIENCE AND 2EMOTE 3ENSING  3YMPOSIUM  PP n    2 + 2ANEY  h4HE DELAY DOPPLER RADAR ALTIMETER v  )%%% 4RANSACTIONS ON 'EOSCIENCE AND 2EMOTE  3ENSING  VOL   PP n     * 2 *ENSEN  h$ESIGN AND PERFORMANCE ANALYSIS OF A PHASE 
 49. Illahy, 1:. T.. 
 Constrained feed. Figure 8.2 1 shows a two-dimensional-scanning array which is sometimes  known as a parallel-.ieriesfeeti. Each element has its own phase shifter. 
 Few, if any, full-polarimetric  data sets exist of the type described above for single polarizations. For more complete  discussions of radar polarimetry, consult references Ulaby and Elachi,162 Sletten and  McLaughlin,163 and van Zyl and Kim.164 Since polarimetric radars use defined phases for both transmit and receive, the  signals must be described in the form used for elliptical polarization. This is illustrated  in Figure 16.45. 
 92. Cindrich. I., J. 
 When the target range was reduced to 1 mile, the Leigh Light was switched on. Using the blind bombing attack facility, the pilot would ﬂy the aircraft on the target ’s bearing at a constant height between 500 ft and 1000 ft and the bombs would be released automatically. The pilot had an override switch ‘should the target turn out to be friendly ’[1]. 
 C/L = ratio of rms clutter power to limit level. (Fror,~ Ward arrd  Shradcr," Courtesy 1 EE E.)  However, when tlie MTI improvement factor is not great enough to reduce the clutter  sufficiently..the clutter residue will appear on the display and prevent the detection of aircraft  targets wliose cross sections are larger than the clutter residue. This condition may be pre-  vcritcd by setting tlic liniit level L, relative to the noise N, equal to the MTI improvement  factor I; or L/N = 1. 
 SITIVITY ! SLOW !'# ALLOWS THE AMPLITUDE NOISE TO MODULATE THE TRUE TRACKING 
 SEC.1.7] WARTIME RADAR DEVELOPMENT 15 and anequipment forenabling night fighters tohome onenemy aircraft (called AI, foraircraft interception). Work was concentrated onASV first, and anexperimental equipment was successfully demonstrated during fleet maneuvers inSeptember 1938. Experimental AIequipment was working byJune, 1939, and itwas demonstrated tothechief ofRAF Fighter Command inAugust ofthat year. 
 Klystron . The original klystrons employed resonant cavities that restricted their  bandwidth. The bandwidth of a klystron, however, increases as its power increases. 
 2.AnAFC unit forboth radar and beacon local oscillators. 3.Ani-fstrip containing theentire i-famplifier, thesecond detector, and avideo cathode follower. 4.Power supply. 
 Second, its performance in sea clutter will be enhanced, as  the grazing angle to the sea will be closer to horizontal, thereby lessening the reflection  coefficient of the clutter. The long range performance of the auxiliary system is, of  course, compromised by its low position. Moving Platform. 
 38Thisis amorecorrectdescription ofthesingledominant scatterer modelthanthechi-square with m=2.However ithasbeenshownthatthechi-square withm=2approximates theRicewhen thedominant-scatterer powerisequaltothetotalcrosssectionoftheother,smallscaHerers, andsolongastheprobability ofdetection isnotlarge.4J. l'l~e log-norrnal clistrit~r~tic~rl has ;tlso t3ccrl cor~sidercd for represet~tir~g target echo fluctir:t-  tions. It can be expressed as  wllcre sd = standard deviation of In (a/a,), and a, = median of a. 
 pp. 575- 584, September, 1976.  53. 
 Forexample, ifthearrayantenna hadanaperture of5 mandifthewrap-up- factorwere15,itwouldtake0.25liStofillthearray.Thepulsewidthshouldbelongcompared tothistimeifdistortion isnottoresult. Afrequency-scan radarcanradiateundesirahle gratinglobes,justascananyotherarray. iftheelectrical spacing between elements istoolarge.FromEq.(8.10h), therelationship between theangleOgatwhichthefirstgratingloheappears, andtheangleOntowhich th~main beamissteered, isgivenby IsinOg-sin00I=Aid Ifweassumethatthegratinglobecanbetolerated ifitislocatedat±90°,then 11+sin00I:s:;Aid(8.20) (8.21) Thelimiting scananglefortheappearance ofgratinglobesisshownbythedashedcurvesin Fig.8.15forthetwocasesd=0.5Aoand0.6Ao.Theonsetofthegratinglobecanselalimitto themaximum angleofscan.Theappearance ofgratinglobesisnotsymmetrical about00=O. 
  .   30!#% 
 ARRAY RADAR v 2ADAR   4OULOUSE  &RANCE  /CTOBER n    2 &ANTE  2 $AVIS  AND 4 'UELLA  h7IDEBAND CANCELLATION OF MULTIPLE MAINBEAM JAMMERS v  )%%% 4RANS  VOL !0n  NO   PP n  /CTOBER   & % #HURCHILL  ' 7 /GAR  AND " * 4HOMPSON  h4HE CORRECTION OF ) AND 1 ERRORS IN A COHERENT  PROCESSOR v )%%% 4RANS  VOL !%3n  NO   PP n  *ANUARY   + 'ERLACH  h4HE EFFECT OF )  1 MISMATCHING ERRORS ON ADAPTIVE CANCELLATION v  )%%% 4RANS    VOL !%3n  NO   PP n  *ULY   + 'ERLACH AND - * 3TEINER  h!N ADAPTIVE MATCHED FILTER THAT COMPENSATES FOR )  1 MISMATCH  ERRORS v )%%% 4RANS  VOL 30n  NO   PPn  $ECEMBER   ! &ARINA AND , /RTENZI  h%FFECT OF !$# AND RECEIVER SATURATION ON ADAPTIVE SPATIAL FILTERING OF  DIRECTIONAL INTERFERENCE v 3IGNAL 0ROCESSING  %LSEVIER  VOL   NO   PP n    ! &ARINA  2 3ANZULLO  AND , 4IMMONERI  h0ERFORMANCE LIMITATIONS AND REMEDIES IN ADAPTIVE  SPATIAL FILTERING WITH TIMING ERRORS v  3IGNAL 0ROCESSING  %LSEVIER  VOL   NO   PP n   &EBRUARY   $ 2 -ORGAN AND ! !RIDGIDES  h!DAPTIVE SIDELOBES CANCELLATION OF WIDE 
 Such amap may comprise ineffect some 105to106separate “elements” ofinformation similar tothe elements from which atele- vision picture orahalf-tone cutisconstructed. This initself isnocause forcomplacency; anordinary photograph, recorded inafraction ofa second, usually contains much more information. Indeed, the unini- tiated, comparing therather fuzzy radar picture with thepin-point detail ofthe photograph, may conclude that the obvious deficiencies ofthe former merely betray theprimitive state oftheart, and that vast improve- ment indistinctness ofdetail istobeexpected inthe normal course of development. 
 #OMB #)#  &ILTERS  )N DECIMATION OR INTERPOLATION APPLI 
 f$Ec.614] PRECISION TRACKING OF ASINGLE TARGET 209 embodied inthe design because itsprecision offollowing is,unlike the accuracy ofmanual tracking, not subject tohuman errors arising from combat stresses and fatigue> Gr3t.-,,.:>., Inorder toensure that the error signals are~easured with respect tothedesired radar echo only, and also toprovide acontinuous measure- ment ofrange, two type Jdisplays arepresented tothe range operator ofthe radar. These are circular range sweeps (Sec. 6.4) with radial signal deflection. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 8.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 SAW Devices for LFM Pulse Compression. 
 Theposition ofthetargetechointhefrequency spectrum depends uponitsvelocity relativetothatoftheradaraircraft.Ifthetargetaircraftapproaches theradaraircraftheadon (fromtheforward sector),thedoppler frequency shiftofthetargetwillbegreaterthanthe doppler shiftsoftheclutterechoes,asshowninFig.4.36.Afiltercanbeusedtoexcludethe clutterbutpassthetargetecho.Similarly, ifthetargetsarereceding fromoneanotheralong headings 1800apart,thetargetdoppler frequency shiftwillagainlieoutsidetheclutterspec­ trumandmaybereadilyseparated. fromtheclutterenergybyfilters.Inothersituations where theradarmaybeclosingonthetargetfromthetailorfromtheside,therelativevelocities may besmallandthetargetdoppler will,liewithin theclutterdoppler spectrum. Insuchsituations thetargetechomustcompete withthedutter energyforrecognition. 
 11, pp. 121-131, 1973. 4. 
 The leakage loss vs. spacing  relationship for Figure 12.8 a can also be computed using an equivalent circuit, with  shunt susceptance, b, developed by Mumford,7 the source of the nomograph6:  b se bd s= − −   =+−λ πln. /0 83 1 1 12Leakage L oss/ /4 (12.17) FIGURE 12. 
 16.15 The oscillator tube ismounted, with itsaxis vertical, inablackemd mu-metal shield visible totheleft. Asingle pickup loop isconnected to two lines viaadecoupling fitting. Atunable echo box (Johnson Service Company Model TS-270/UP) iscoupled totheoscillator byarotatable ““***** ● 9-W*, ****9,*** ●*1 *****.*.4 9* loop, thelever arm ofwhich isvisible close tothe oscillator. 
 edges at the E-field peaks in the middle of the horns. This results in the need for the top and bottom matching stubs seen in Fig. 18.13. 
 13.5.)  A knowledge of the statistics of the clutter is important in order to properly design a  CF AR (constant false-alarm rate) receiver 115 and to avoid the loss associated with a receiver  detector designed on the basis of the improper statistical model of clutter.  Theory ofsea clutter. In the past, attempts were made to exp lair: the mechanism of sea clutter  by reflection from a corrugated surface, 16 by backscatter from the droplets of spray thrown by  the wind into the air above the sea surface, 16• 1 7 or by backscattering from small facets, or  patches, on the sea surface.18 None of these models were able to explain adequately the  eAperimental observations. 
 169  15.8 General and Supporting Literature ............................................................................... 169     . Radar System Engineering  Chapter 1 – History of Radar Technology  1     1 The History of Radar Technology   Much has been composed on the history of Radar technology, particularly since it is possible to  find sections about it in almost every book on the theme of Radars. 
 34. Dunn. J. 
 The result is a decrease in efficiency. Higher current densities also require  stronger magnets to keep the electron beam confined, leading to larger volume and  weight. Thus, simply lowering the beam voltage and increasing the current density  does not usually provide a net advantage. 
 AVERAGED TRACK 
 12Figure 1.11 - Ducting areas. 13Paciﬁc Ocean (Area 6). Frequent occurrences of ducting around Guadalcanal, the east coast of Australia, and around New Guinea and Koreahave been experienced. 
 There are a large variety of tracking-radar systems, including some that achieve  simultaneously both surveillance and tracking functions. A widely used type of  tracking radar and the one discussed in detail in this chapter is a ground-based sys - tem consisting of a pencil-beam antenna mounted on a rotatable platform with servo  motor drive of its azimuth and elevation position to follow a target (Figure 9.1 a).  Errors in pointing direction are determined by sensing the angle of arrival of the  echo wavefront and corrected by positioning the antenna to keep the target centered Chapter 9 ch09.indd   1 12/15/07   6:06:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 However, this simple theory neglected to account for the effects of a rough sea or the fact that the backscatter from a submarine target would have been from a number of scattering centres atvarious heights above the sea surface. In June 1942 the Operational Research section, HQ Coastal Command, reported on the performance of ASV Mk. II [ 9] in both LRASV and SRASV versions. 
 Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 100     11.5 Radar Cross -Section of Simple O bjects   The behaviour of the Radar backscattering cross -section as a function of the parameters listed  in section 11.1 is best understood by the consideration of simple bodies, of which will be di s- cussed in the following sections.   11.5.1  Sphere   In practice the sphere is the simplest available scattering body.  Since the sphere offers the  same view from all approaching directions, the back scattering is independent on the rotation  of the sphere. 
 It also has the practical advantage  that the magnitude of the conical-scan modulation is amplified because pulse stretching puts  more of the available energy at the modulation frequency. The puhe repetition frequency must  be sufficiently large compared with the conical-scan frequency for proper boxcar filtering. If  156INTRODUCTION TORADAR SYSTEMS Torotaryjoint onantenna r-------j Ref. 
  IS THE FORMER RESEARCH RADAR OPERATED BY .#!2  #OURTESY  OF  5NIVERSITY  #ORPORATION  FOR  !TMOSPHERIC 2ESEARCH Ú   "OULDER  #/  . 
    PP n  *ANUARY    # 
 These correspond to frequencies in the Rayleigh and the  low-resonance regions. The use of such frequencies is said to provide overall dimensions,  approximate shape, and material composition. Instead of the impulse response, the response of  a target to a ramp function is sometimes more convenient to work with, especially when the  longer wavelengths are used to obtain target classification. 
 Cloud droplets are regarded here as those water or ice particles having radii smaller than 100 jxm, or 0.01 cm. For wavelengths of incident radiation well in excess of 0.5 cm, the attenuation becomes independent of the drop-size distribution. The generally accepted equations for attenuation by clouds usually show the moisture component of the equations in the form of the liquid-water content (grams per cubic meter). 
 2S S   WHERE S IS THE RMS SURFACE SLOPE AND  2 IS THE FLAT 
 56, ·pp. 1940-1951, November, 1968.  7.1. 
 Noveniber. 1964.  82. 
 The equation  fc = Dm / (4 tan(yr / 2)) (12.25) defines the equivalent focal length, and the focal length ratio or magnification m is  given by  m = fc / fm = (e + 1) / ( e − 1) (12.26) FIGURE 12. 23 Cassegrain dual reflector antenna systems (the larger surface is the main reflector  and the smaller surface is the subreflector): ( a) ray optics ( b) typical axial configuration,20 and ( c)  offset configuration ch12.indd   22 12/17/07   2:31:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 APERTURE PRODUCT THAN GIVEN BY STANDARD DESIGNS  YET THIS IS SELDOM ALLOWED 4HE REQUEST FOR A LOW SIDELOBE LEVEL HAS TO BE TRADED OFF WITH THE CORRESPONDING DEGRADATION OF THE MAIN 
 Ostroff et al., "Solid-State Transmitters," Artech House, Norwood, Mass., 1985.} lector depletion-layer transit time, and the collector capacitance-resistance charg- ing time. High-frequency transistor design is concerned with optimizing the phys- ical parameters that contribute to the time-delay components.5 For high-power chips, the design challenge is to maintain a uniform high cur- rent density over a large emitter area with a minimum temperature rise. High- frequency devices require shallow, narrow, high-resistance base regions under the emitter region. 
 similar to those produced in phased arrays.) The problem of high sidelobes can  Ilc rctl\~ccd by overl:lppirlg the antentla apcrturcs. With reflector antennas. this results ill a loss  of :tr~gle ser~sitivity arid atlte~ltia gain. 
 P : General Solution of the Luneburg Lens Problem, J. Appl.. Phys., vol. 
 HANDED  )T IS WELL KNOWN THAT LINEAR TARGETS SUCH AS WIRES ACT AS DEPOLARIZING FEATURES AND THAT A LINEARLY POLARIZED CROSSED DIPOLE ANTENNA ROTATED ABOUT AN AXIS NORMAL TO A LINEAR TARGET SUCH AS A WIRE OR PIPE PRODUCES A SINUSOIDAL VARIATION IN RECEIVED SIGNAL (OWEVER  THE NULL POINTS ARE A DISTINCT DISADVANTAGE  BECAUSE THE OPERATOR IS REQUIRED TO MAKE TWO SEPARATE  AXIALLY  ROTATED MEASUREMENTS  AT EVERY POINT TO BE SURE OF DETECTING PIPES AT UNKNOWN ORIENTATIONS !N ATTRACTIVE TECHNIQUE IS TO RADIATE A CIRCULARLY POLARIZED WAVE  WHICH AUTOMATICALLY ROTATES THE POLARIZED VECTOR IN SPACE AND HENCE REMOVES THE DIRECTION OF SIGNAL NULLS 4HESE TECHNIQUES CAN BE USED TO DISCRIMINATE IN FAVOR OF THE TARGET &OR EXAMPLE  A RIGHT 
 IEEE Signal Process. Mag. 2014 ,31, 16–26. 
 Remote Sens. Lett. 2013 ,51, 1826–1835. 
 G. F. Earl and M. 
 FIGURE  2. 97  Insects with and without STC and range 25 miles: ( a) bats and insects seen with MTI and  (b) bats and insects seen with MTI and STC ch02.indd   97 12/20/07   1:52:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 STATE INFORMATION AND UNMASK TARGETS HIDDEN IN CLUTTER ! COMPELLING EXAMPLE IS PRESENTED IN &IGURE   WHERE A RANGE CELL CONTAINING A  SHIP TARGET TRAVELING AT A SPEED OF  KNOTS HAS BEEN INTERROGATED AT EIGHT RADAR FREQUEN 
 The resulting sampled spectrum, shown in  Figure 25.4 b and c, contains overlapped, or aliased, spectral components that add and  represent corruption of the signal. Figure 25.5 repeats this Nyquist analysis for a bandpass signal —a signal not  containing spectral components at or near 0 Hz. Figure 25.5 a shows a real bandpass  signal with two-sided bandwidth B and composed of positive-frequency and negative- frequency spectral components, each of bandwidth B/2, that are complex-conjugated  mirror images. 
 DICTABLE )N THIS CASE  TARGET LOCATION ACCURACY IS OFTEN SET BY THE P 4 ESTIMATION ERROR -ULTISTATIC ,OCATION   -ULTISTATIC LOCATION TYPICALLY USES MULTIPLE TRANSMITTERS  OPERATING WITH ONE RECEIVER OR MULTIPLE RECEIVERS OPERATING WITH ONE TRANSMITTER %LLIPSES OF CONSTANT RANGE 
 19. Ruck, G. T.. 
 Rept. 700, Dec. 27. 
 Other studies corroborate this behavior .39FIGURE 15.8  Example of forcing a power-law fit (compare data points with  those in Figure 15.6) ( after A. H. Chaudhry and R. 
 M.: Survey of Airborne Microwave Refractometer Measurements, Proc. I RE, voL 43,  pp. 1405-1411, October, 1955. 
 It should be noted that sampling 3D antenna patterns is not limited to planar cuts as described above. Sometimes it is meaningful and convenient (from a measuring-technique viewpoint) to take conical cuts, i.e., the intersections of the 3D pattern with cones of various angular widths centered on the electrical (or me- chanical) axis of the antenna. The typical 2D pattern shown in Fig. 
 A. Zachary: Phase-Amplitude Monopulse System, IRE Trans., vol. MIL-6, pp. 
    F IS THE  RADAR FREQUENCY  AND C THE VELOCITY OF LIGHT 7ITH THIS INSIGHT  THE SECOND 
 Stark, L.: Microwave Theory of Phased-Array Antennas-A Review, Proc. IEEE, vol. 63. 
 Each segment will be correct at two points and will have a maximum error at the ends and center. The magnitude of the error7 in- creases with the length ratio of the segment. Figure 3.11 shows how this error changes with segment length ratio (also called gain per segment). 
 Traditional point-based monitoring approaches such as ground leveling and global positioning system (GPS) techniques could not provide sufﬁcient samples required by land subsidence mapping [ 19]. In recent years, interferometric synthetic aperture radar (InSAR) technology has been rapidly developed to cover a large geographic area. InSAR method is low-cost and effective [ 20,21]. 
 TEM OF N LINEAR HOMOGENEOUS EQUATIONS IN N  UNKNOWNS IS GENERATED )F THE BOUNDARY  CONDITIONS PERMIT THE DECOUPLING OF THE EQUATIONS  THE NUMBER OF UNKNOWNS MAY BE HALVED TO N EQUATIONS IN N UNKNOWNS  4HE COEFFICIENTS OF THE RESULTING MATRIX INVOLVE ONLY THE ELECTRICAL DISTANCES  IN WAVELENGTHS  BETWEEN ALL PATCHES TAKEN BY PAIRS  AND THE ORIENTATION OF PATCH SURFACE NORMALS 4HE UNKNOWN FIELDS MAY BE FOUND BY INVERTING THE RESULTING MATRIX AND MULTIPLYING THE INVERTED MATRIX BY A COLUMN MATRIX REPRESENTING THE INCIDENT FIELD AT EACH PATCH 4HE SURFACE FIELDS ARE THEN SUMMED IN INTEGRALS SIMILAR TO %QS  AND  TO OBTAIN THE SCATTERED FIELD  WHICH THEN MAY BE INSERTED IN %Q  TO COMPUTE THE 2#3 &)'52%   4HE METHOD OF MOMENTS DIVIDES THE BODY SURFACE INTO A COLLECTION OF DISCRETE PATCHES 4HIS  PLANFORM OF THE 53 !IR &ORCE " 
  !DVANCED RADAR ALTIMETER )NSTRUMENT DESIGN AND PRE 
 E. Hudson, S. O. 
 The technique is limited, at small offset frequencies, by thermal noise that com- petes with the low values of phase deviation permitted by the servo. Even with this limitation, one is considerably better off than with a cavity bridge whose sen- sitivity falls off rapidly at small offsets. Without the aid of commercial phase- bridge instrumentation, it would have been difficult to develop the crystal sources having much reduced phase noise at close-in frequencies. 
 15.7 Suppression of multiple clutter sources by using a doppler filter bank. The output of each doppler filter is envelope-detected and processed through a cell-averaging CFAR processor to suppress residues due to range-extended clutter which may not have been fully suppressed by the filter. As will be discussed later in this chapter, the conventional MTI detection sys- tem relies on a carefully controlled dynamic range in the IF section of the radar receiver in order to ensure that clutter residues at the MTI output are suppressed to the level of the receiver noise or below. 
 FT TOWER IN FLAT COUNTRY NEAR !TLANTIC #ITY  .EW *ERSEY 7ITH NORMAL PROPAGATION  THE EXPECTED LINE 
 Any use is subject to the Terms of Use as given at the website. Radar Receivers. 6.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 Stretch Processing.  Stretch processing is a technique frequently used to pro - cess wide bandwidth linear FM waveforms. 
 5. F. M. 
 In either case, the filters around the main-beam clutter are blanked to minimize false alarms on main-beam clutter. The choice between these options is a tradeoff of quantization noise and com-MAXlMUM RANGE RESOLVED BY AAND BCORRELATORS CFARTHRESHOLD UNAMBIGUOUSRANGE (LOGSCALE)AMPLITUDE (dB) . plexity versus the filter-weigh ting loss. 
 MTT- 1 1. pp. 29 1-296. 
 MAL RADAR OPERATING MODES AND REQUIRES ONLY A SMALL FRACTION OF THE AVAILABLE RADAR RESOURCES !NOTHER  TECHNIQUE  TO  PERFORM  IN 
 T. Taylor, “Design of line-source antennas for narrow beamwidth and low sidelobes,” IRE  Trans ., vol. AP-3, pp. 
 UP  DOUBLE &- 
 Phase  detection occurs as it1 tile conventional monopulse. Another single-channel system SCAMP  converts the sum and the two difference signals to different IF frequencies and amplifies them  simultaneously in a single, wide-band amplifier.20 The output is hard-limited to provide the  effect of an instantaneous AGC. The three signals after limiting are separated by narrowband  filters and then converted to the same IF frequency for further processing. 
 The beam scanning prolongs the integration time of sliding spotlight mode which can be calculated as Ta=2Rctan(λ/2D)/slashbig Vg, where λis the wavelength, Dis the size of azimuth antenna and Vgis the ground velocity which is given as follow Vg=Vr−Hsat cosθ/prime i·|kω|·sec2/parenleftbig θsq(η)/parenrightbig (3) where θ/prime iis the ground incident angle and θsq(η)=θsq0+kωηis the instant squint angle. It can be seen that kωis the key factor which determines the ground velocity and the integration time. The integration time and theoretical azimuth resolution as a function of kωare shown in Figure 2. 
 BANDWIDTH PRODUCT  4" . #OMPRESSED PULSE WIDTH  " S .   S . $OPPLER RESOLUTION  4 .S4!",%     . 0ULSES #ONTIGUOUS IN 4IME AND &REQUENCY. n°ÓÈ  2!$!2 (!.$"//+  PROCESSED COHERENTLY 4HE ORDER IN WHICH THE FREQUENCIES ARE GENERATED GREATLY INFLU 
 Although not classified in the strict sense, Kosmos came to view largely  after the launch of its technical successor, Almaz (Russian and Arabic for diamond in  the rough ). Preceding these Soviet SARs were a series of real-aperture radars, known  as Okean  (and by other names). Almaz was a very interesting radar, in that it provided  unique S-band SBR imagery of the Earth’s surface. 
 TION $3$  THAN POWER 
 Over water the surface duct is also called the evaporation duct, since it is the result  of water vapor evaporated from the sea. A duct which lies above the surface is called an  elevated duct. Surface ducts apparently are more usual than elevated ducts. 
 NOISE KNOWN AS SPECKLE 4HE STANDARD DEVIATION OF SPECKLE IS REDUCED BY SUMMING AVERAGING  MANY STATISTICALLY INDEPENDENT WAVEFORMS TOGETHER 3TATISTICAL INDEPENDENCE BETWEEN SEQUENTIAL  RETURNS OBSERVED BY  A RADAR ALTIMETER DEPENDS PRIMARILY ON THE RADAR PULSE REPETITION RATE  THE ANTENNA SIZE  THE SPACECRAFT VELOCITY  AND ON THE SEA SURFACE CONDITIONS  4HE ANTENNA WAS A  
 9.31. The display console isshown in Fig. 6.25. 
 The pulse-doppler mode of operation has the further advantage in  that each beam can operate with a single antenna for both transmitter and receiver, whereas a  CW radar must usually employ two separate antennas in order to achieve the needed isolation.  However, pulse systems suffer from loss of coverage and/or sensitivity because of" altitude  holes." These are caused by the high prf commonly used with pulse-doppler radars when it is  necessary to achieve unambiguous doppler measurements. The high prf, although it gives  unambiguous doppler, usually results in ambiguous range. 
 The echo signal from a string depends on the length and diameter of the string,  its tilt angle with respect to the incident wave, and its dielectric constant. No matter  what the tilt of the string, it will be presented normal to the line of sight twice in a  complete rotation of the target and may cause a spike in the RCS pattern that could be  erroneously attributed to the target unless otherwise accounted for. The RCS of a string  rises with the fourth power of its diameter in the Rayleigh region (see Figure 14.4),  and for a given tensile strength, the diameter rises only as the square root of the load  to be supported. 
 IT-20, no. 5, pp. 591–598, September 1974. 
 Inframing thedefini- tion sobroadly wehave ineffect included, under “receiver,” notonly the rnixer but allassociated r-fcircuits. Itiswell todosoatthis stage, forthe analysis ofthecontribution ofeach part oftheinput system totheover- IR.H.Dicke, ‘(The Measurement ofThermal Radiation atMicrowave Fre- quencies,” RLReport No.787. Seealso Dicke etal.,Phys.Rsu.,70,340(1946). 
 FIELD AMPLIFIERS #&!S   AND MAGNE 
 HAPS  TO CONCLUDE THAT SEA CLUTTER ARISES FROM MULTIPLE SOURCES  WHICH WE ALREADY KNOW /N THE OTHER HAND  THE IDENTIFICATION OF CHANGES IN THE CHARACTERISTIC  MEASURES OF THESE  PROCESSES EG  FRACTAL DIMENSION AND EMBEDDING DIMENSION  HAVE BEEN PROPOSED AS A WAY TO IDENTIFY THE PRESENCE OF TARGETS IN CLUTTER&)'52%   A  -EASURED SLOPE TOP CURVE  OVER A SAMPLED SURFACE IN THE 'ULF 3TREAM  WITH THE COR 
 , 1. J) ,*.I .'  396INTRODUCTION TORADAR SYSTEMS 17.Lee,Y.W.,andJ.B.Wiesner: Correlation Functions andCommunication Applications, Electronics, vol.23,pp.86-92,June,1950. 18.Singleton, H.E.:ADigital EI~ctronic Couela.lor,Proc. 
 527-532. IEEE Publ. 75 CHO 939-l AES. 
 Other receiver types include the superregenerative, crystal video, and tuned radio frequency (TRF). The superregenerative receiver is sometimes employed in radar-beacon applications because a single tube may function as both transmitter and receiver and because simplicity and compactness are more important than superior sensitivity. The crystal video receiver also is simple but of poor sensi- tivity. 
 C. Cruce, “ECCM Advanced Radar Test Bed (E/ARTB)  systems definition,” IEEE Nat. Aerosp. 
 Ci. R.. and M. 
 Instruments planned for the satellites include radar, radiome- ters, IR, optics, and ultraviolet (UV). These sensors will measure parameters such as winds, clouds, rain, liquid-moisture content, geologic parameters, . ocean currents, etc. 
 39.Fox,A.G.:AnAdjustable Wave-guide PhaseChanger, Proc.IRE.vol.35,pp.1489-1498, Decem­ ber.1947. 40.Seckelmann, R.:Phase-Shift Characteristics ofHelicalPhaseShifters, IEEETrans,vol.MTT-14, pp.24·28,January, 1966. 41.Boxer,A.S.,S.Hershenov, andE.F.Landry: AHigh-Power Coaxial FerritePhaseShifter,IRE TrailS,vol.MIT-9,p.577,November, 1961.. 
 The efficiency of a TWT or a klystron can be improved  by the use of a so-called depressed collector .15,16 With a single collector, a significant  fraction of the power input to the tube is dissipated as heat in the collector. If the volt - age on the collector is reduced (depressed) below the body voltage, the velocity of the  electrons striking the collector is reduced and so is the heat generated in the collector.  Thus, the collector recovers some of the power in the spent electron beam. 
 -   ( 'OLDSTEIN  h3EA %CHO v IN  0ROPAGATION OF 3HORT 2ADIO 7AVES  $ % +ERR ED   -)4 2ADIATION  ,ABORATORY 3ERIES  #HAP   6OL   .EW 9ORK -C'RAW 
 ELEMENT ARRAY IT MAY BE GENERALLY VIABLE  BUT LESS FREQUENTLY FOR A  
 ATION AND NEW DEVELOPMENTS IN SPACEBORNE )N3!2 v IN  0ROCEEDINGS  )3023 7ORKSHOP ON (IGH  2ESOLUTION -APPING FROM 3PACE  (ANOVER  'ERMANY    9 .EMOTO  ( .ISHINO  - /NO  ( -IZUTAMARI  + .ISHIKAWA  AND + 4ANAKA  h*APANESE  EARTH RESOURCES SATELLITE 
 1167 1168, August, 1973.  121 Anderson, I.: Measurements or 20-Cillz Transmission Through a Radomc in Rain, IEEE Trans ..  rnl. 
 Nat. Bur. Stand. 
 At certain angles, almost all the energy is re- flected, causing a null in the element pattern. To guard against these reflections it is best to design the radiators so that higher-order modes are well into the cutoff region. Figure 7.18 shows the results obtained by Diamond,72 using a waveguide array. 
 Inthe ideal case the curve isthe same as the antenna pattern oftheradar; in actual cases itisoften modified by reflections from near-by buildings, hills, etc. Ifcircle breprese,,ts the threshold power fortriggering, the beacon will betriggered only through the sector AOA’. If,however, the values ofreceived power should all beincreased by12dborso(by de- creasing the range tothe beacon), thebeacon would also beinterrogated byside lobes oftheantenna. 
 Scatterometric data are being exploited for many purposes other than oceanic vec - tor winds. Although the “images” generated by a space-based scatterometer may have  only 50-km resolution, their wide swath and frequent revisit intervals are well suited to  synoptic coverage of global-scale phenomena. The multi-year history of scatteromet - ric radars provides an important data set for climate change studies as well as moni - toring seasonal variations. 
 47. Harvey, A. F.: Optical Techniques at Microwave Frequencies, I'roc. 
 R. Meteorol. Soc., vol. 
 RANGE RESOLUTION *ANZA HAS REPORTED DETAILS OF CALIBRATION PROBLEMS WITH A RANGE 
 Thus, there will be an additional  rms angle error proportional to tracking lag and dependent on the AGC time con - stant,40 as illustrated in Figure 9.24. In general, a fast AGC is recommended because it reduces the additional noise  term allowed by slow AGC and the possibility of larger rms tracking errors, which  can be considerably greater than the angle noise with a fast AGC. As previously  discussed, angle noise is significant, mainly at medium and close range where target  angle rates are greatest. 
 Dry snow particles are essentially ice crystals, either single or ag­ gregated. The relationship between Zand snowfall rater is as given by Eq. ( l 3.20) for rain, but  with different constants a. 
 n 1 117;. B = false alarm number, Tr. average time between false alarms, B = bandwidth; (b) integra­ tion loss as a function of 11, the number of pulses integrated. 
 L. Lucas and J. D. 
 Any use is subject to the Terms of Use as given at the website. Sea Clutter. 15.8  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 where for a radar with an antenna beamwidth B and rectangular pulse of length t,  viewing the surface at range R and grazing angle y, the area Af is either  Af = p  (BR)2/4 siny (15.8) for beam-limited conditions (e.g., continuous-wave (CW) or long-pulse radar at high  grazing angles) or  Af = (ct /2)BR/cosy (15.9) for pulse-width-limited conditions (e.g., short-pulse radar at low grazing angles). Real radars do not produce cookie-cutter footprints, however, since the antenna  beam will have a complex profile and the pulse might be shaped. 
 Compared with the former two algorithms, LS-CS-Residual takes similar amount time. T able 1. Time taken (in minutes) by the three algorithms. 
 Setting the threshold has become  intimately connected with the sensitivity time control (STC) of the radar. The fun - damental use of STC is to take out the distance-related dynamic range of received  signals. At close range, STC classically follows an inverse fourth power law, merging  to an inverse cubic law in the region where sea clutter dominates, in accordance with  basic theory. 
 So complex  has the wide field of radar and kindred radio navigational  aids become that we must include Oboe, Gee, Rebecca-  Eureka, and other famous systems. In these it is not  merely a matter of broadcasting a pulse and detecting  the echo: some complex systems include transmitters  which are “triggered off’ by the incoming pulse, and  themselves retransmit a spurt of radio energy which a  suitably placed receiver picks up. Radar is used for  timing, plotting, course-checking, and, indeed, for many  major “Ravigational tasks where tlie écho ofa series of  pulses is not by any means the major feature of the  operation. 
 SEC. 56] SIMPLE DOPPLER SYSTEM 133 that thereturned signal will be10–7 or10–’ times thetransmitted signal involtage, itfollows that amplitude modulation ofthe transmitter would have tobeheld below this value inorder not tobeobtrusive. Though perhaps not impossible this would certainly bedifficult. 
 E. Racette, L. Tian, and E. 
 CESSED INTO TOPOGRAPHIC MAPS 4HIS WAS THE FIRST DEMONSTRATION OF SINGLE 
 HATCHED REGION SHOWN ON &IGURE  )T IS INFORMATIVE TO COMPARE MEASUREMENTS AT DIFFERENT FREQUENCIES BY DIFFERENT  INVESTIGATORS IN DIFFERENT PARTS OF THE WORLD UNDER SIMILAR WIND CONDITIONS &IGURE  DISPLAYS MEASUREMENTS OF VERTICALLY POLARIZED SEA CLUTTER DOWN TO A GRAZING ANGLE OF  FOR WIND SPEEDS OF ABOUT  KT FROM THREE INDEPENDENT EXPERIMENTS USING AIRBORNE RADARS AT # 
 43. Woerrlein, H. H.: Spurious Target Generation Due to Hard Limiting in Pulse Compression Radars,  IEEE Trans., vol. 
 The characteristics  of the return signal from the ocean surface are discussed as a basis for understanding the altimetry  process. The primary measurements provided by the altimeter are listed along with a description of  altimeter hardware implementation. The processing and corrections to the raw measurements to yield  the end-user data products are presented, followed by a summary of the altimeter's in-orbit performance. 
 no conclusive decision can be reached and another observation is made.  The three choices are again examined on the basis of the combined observations. If no  decision is reached as to the presence of signal or the presence of noise, another observation  is made. 
 Therefore theoptimum gatingwaveform appearsasthetimederivative ofthereceived waveform, ifthenoisespectrum isconstant. Byapplying theconvolution theorem toEq.(11.6),theFouriertransform ofthe outputSo(J)isequaltoSlI(J)S*(J), or j2nJIS(J) 12 So(J)='IN;{IYI 2-- (11.10) Thisisatransform ofanoddfunction. Thegatingsignalandthematched filterarerelatedtooneanother. 
 FIG. 25.2 Contours of constant signal-to-noise ratio, or ovals of Cassini, where the baseline = L and k = 3OL4. The ovals of Fig. 
 Uhas the same size of the matrix Xwhile Sis a real valued diagonal matrix of order Nand Vis a complex orthonormal square matrix of order N: UH·U=IN (2) and VH·V=IN (3) Sis the matrix containing the singular values of the matrix decomposition, sorted along the diagonal from the highest value to the lowest. If a right multiplication for matrix V of both terms in (3) is applied, it can be usefully restated in another form: X·V=U·S=E (4) 90. Sensors 2019 ,19, 1649 The Vmatrix is the matrix performing linear combinations of the columns of the data matrix Xto obtain E, an orthogonal matrix. 
 Any use is subject to the Terms of Use as given at the website. Reflector Antennas.  REFLECTOR ANTENNAS  12.416x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 laminates and low-density cores to attain high transmission performance over large  frequency bands. Dielectric Layers with Metal Inclusions . 
 TICULAR TYPE OF TARGET  AN AUTOMOBILE RATHER THAN A TRUCK  OR A STARLING RATHER THAN A SPAR 
 TheabilityoftheFM-CW radartomeasure rangeprovides anaddi­ tionalbasisforobtaining isolation. Echoesfromshort-range targets-including theleakage signal-may beattenuated relativetothedesiredtargetechofromlongerrangesbyproperly processing thedifference-frequency signalobtained byheterodyning thetransmitted and received signals. IftheCW carrierisfrequency-modulated byasinewave,thedifference frequency obtained byheterodyning thereturned signalwithaportionofthetransmitter signalmaybeexp(l.nded inatrigonometric serieswhosetermsaretheharmonics ofthemodulating frequency.l~ .9.2t1 Assume theformofthetransmitted signaltobe sin(2rrfot+~£sin2rrfmt) wherefo=carrierfrequency fm=modulation frequency 11:(=frequency excursion (equaltotwicethefrequency derivation) Thedifference frequency signalmaybewritten eD=Jo(D)cos(2~(dt-¢o)+2J1{D)sin(2~rdt-¢o)cos(2nfmt-¢m) -2J2(D)cos(2rrfdt-¢o)cos2(2~rmt-¢m) -2J3(D)sin(2~(dt-¢o)cos3(2nfmt-¢m) +2J4(D)cos(2rr/dt-¢o)cos4(2~rmr-¢m)+21s(D)." (3.16). 
 RIER FREQUENCY $ISCRETE MULTIPLICATIVE NOISE SOURCES GENERATE DISCRETE SPECTRAL LINES THAT CAN CAUSE FALSE ALARMS 3YSTEM STABILITY IS CHARACTERIZED BY THE OVERALL TWO 
 Most radars utilize the equivalent of the Neyman-Pearson Observer and  operate with a fixed number of pulses. However, the detection decision might very well be  made on the basis of only a few observations or possibly a single observation, and it would not  be necessary to record the later observations that occur once the threshold has been crossed.  Hence there may be some advantage to using a flexible detection criterion which takes account  of this fact. 
 McCall, “Bistatic clutter in a moving receiver system,” RCA Rev ., pp. 518–540,  September 1969. ch23.indd   32 12/20/07   2:21:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 SPACE TRADES START WITH THE CANONICAL CASE 4HE  TRADE 
 (8.15). This provides a relatively simple  means for obtaining electronic phase shift. Although parallel feeding of a frequency-scan array  is possible, it is usually simpler to employ series feeding, as in Fig. 
 TRIBUTION WHERE THE STANDARD DEVIATION IS EQUAL TO THE MEAN VALUE IN THE INTENSITY IMAGE MULTIPLICATIVE CHARACTERISTIC  &OR MULTILOOK PROCESSING  THE GEOMETRIC RESOLUTION WILL  DEGRADE AS THE NUMBER OF LOOKS INCREASES AND THE SPECKLE STATISTICS OF THE INTENSITY  IMAGE OBEY A GAMMA DISTRIBUTION  WHERE THE STANDARD DEVIATION DECREASES WITH THE SQUARE ROOT OF THE NUMBER OF INDEPENDENT LOOKS  3!2 IMAGES ARE USEFUL FOR SURVEILLANCE AND RECONNAISSANCE APPLICATIONS (OWEVER   JAMMING COULD MAKE 3!2 IMAGES UNUSABLE 4HE USE OF %##- IS  THEREFORE  ESSEN 
 The detection characteristics (probability of detection as a function of the probability of  false alarm, signal-to-noise ratio, and the number of hits integrated) for the logarithmic  receiver have been computed by Green,44 following the methods of Mar~um.~~ For 10 pulses  integrated, the loss with the logarithmic receiver is about 0.5 dB, while for 100 pulses in-  tegrated, the loss is about 1.0 dB. As the number of pulses increases, the loss due to a logarith-  mic detector approaches a maximum value' of 1.1 dB.45  Zero-crossings detector. The information contained in the zero crossings of the received signal  can, in principle, be used for detecting the presence of signals in noise. 
 OF 
 For example, a midcourse mode employing inertial or command guid- ance can be used to bring the missile within the terminal guidance range (typically the last 10 guidance time constants or a few kilometers from intercept). The tar- get coordinates in angle (antenna pointing) and range and/or velocity (doppler), provided by prelaunch data or by command updates during flight, initialize the seeker. The target uncertainty is searched by the seeker, and when the target is acquired, the missile transitions into the terminal phase of flight. 
 WEATHER LONG 
 RESPONDING DOPPLER BANDWIDTH 4O FIRST ORDER  THE AZIMUTH RESOLUTION IS GIVEN BY   R2. 
   -4) 2!$!2  Ó°xx &INALLY  &IGURE  SHOWS THE AVERAGE 3#2 IMPROVEMENT OF THE  D" #HEBYSHEV  DOPPLER FILTER BANK AS WELL AS THE OPTIMUM CURVE FROM &IGURE   AS A FUNCTION  OF THE RELATIVE SPECTRUM SPREAD OF THE CLUTTER /WING TO THE FINITE NUMBER OF FILTERS IMPLEMENTED IN THE FILTER BANK   THE AVERAGE 3#2 IMPROVEMENT WILL CHANGE BY A SMALL  AMOUNT IF A DOPPLER SHIFT IS INTRODUCED INTO THE CLUTTER RETURNS 4HIS EFFECT IS ILLUSTRATED BY THE CROSS 
 h–S loss curve . It can be seen in Figure 11that, as hincreases, the SNR loss gradually becomes severe. We assume that the SNR of the imaging result is 20 dB when h=0m . 
 Develop., Antenna Arrays Sec., Abstr ., University of Illinois, Urbana, 1962. 27. M. 
 in arrays. 288  Tuning:  klystron. 203  magnetron, 199 - 200  Twin-slab toroidal phase shifter, 294  Twist reflector, 242 ,243  'l'wo-frequency CW. 
 Phys. Lab. Rept . 
 CANCELLATION $0#! BUT ARE UNSATISFACTORY WHEN DOUBLE 
 Gill, T. P.: "The Doppler Effect," Academic Press, New York, 1965.  24. 
 Note that  it is implicitly assumed in the above definition that signal and clutter are both observed  after pulse compression. The SCV of two radars cannot necessarily be used to compare  their performance while operating in the same environment, because the target-to-clutter  ratio seen by each radar is proportional to the size of the radar resolution cell and may  be a function of frequency. Thus, a radar with a 10- µs pulse length and a 10° beamwidth  would need 20 dB more subclutter visibility than a radar with a 1- µs pulse and a 1°  beamwidth for equal performance in a distributed clutter environment. 
 ", 
 53. C. C. 
 GETS MUST COMPETE WITH FOR DETECTION .ONLINEARITIES IN THE SYSTEM CAN ALSO CAUSE DISCRETE SPURIOUS SPECTRAL SIGNALS THAT CAN BE MISTAKEN AS TARGETS 4HE INSTANTANEOUS DYNAMIC RANGE OF THE SYSTEM GOVERNS THE SYSTEM LINEARITY AND HENCE SENSITIVITY IN A STRONG CLUTTER ENVIRONMENT 4HE DRIVING FACTOR UPON STABILITY REQUIREMENTS IS WHEN THE MAIN 
 In [ 10], performance of a prototype installation in a Beau ﬁghter was reported. The Beau ﬁghter was mainly used in a strike role and only had forward- looking homing antennas. It was found that the Yagi array being used fortransmission interacted with the quarter wave dipoles being used on receive. 
 TRONICALLY POINTS THE ANTENNA SLIGHTLY AHEAD OF AND BEHIND OF BORESIGHT EACH PULSE SO THAT A LEADING AND LAGGING PAIR ARE TAKEN FROM SUCCESSIVE RETURNS TO OBTAIN THE EFFECT OF THE ANTENNA REMAINING STATIONARY &IGURE  SHOWS THE IMPROVEMENT OBTAINED BY $ICKEY AND 3ANTA  FOR SINGLE 
 BEAM COMPENSATION RESULTS !GAIN  THE PERFORMANCE VERSUS DOPPLER FREQUENCY IS IMPORTANT FOR EVALUATING  OVERALL RADAR DETECTION PERFORMANCE !NTENNA SIDELOBE LIMITED PERFORMANCE CAN BE APPROXIMATED BY PERFORMING THE LOWER INTEGRAL OF %Q  OVER THOSE ANGLES THAT MAP INTO A GIVEN DOPPLER FILTERS PASSBAND 4HE NOISE NORMALIZATION TERM  K  MUST ALSO BE MODIFIED TO REFLECT THE CASCADED NOISE GAIN OF THE -4) AND DOPPLER FILTER BANK AS .K 7 7 7 K . 7 GI I. II I. 
 Any sensitivity gained by directivity in elevation directly improves radar performance. This is in contrast with azimuth directivity for transmitting, where an increase in gain is accompanied by a decrease in area coverage. The AN/FPS 118 over-the- horizon (OTH) radar3 does not employ steerable directivity in elevation but covers all necessary radiation angles with one broad elevation beam. 
 A long pulse is desired when the radar is  limited by noise in order to increase the signal-to-noise ratio. When clutter dominates noise, a  long pulse decreases the signal-to-clutter ratio. (When pulse compression is used, the pulse  472INTRODUCTION TORADAR SYSTEMS wherePt=transmitter power G=antenna gain At.'=antenna effective aperture R=range ac=cluttercross-section, whichisequal10 ac=aOAc=aOROB(cr/2)sec¢ (13.4) (13.5) (13.6)rathathanwherec=velocityofpropagation. 
 Sensors 2019 ,19, 346 of anisotropic targets under different azimuth look angles [ 11,12]. Some researchers use polarimetric CSAR to obtain complete scattering information of targets. Xue et al. 
 Scanning loss can be important for rapid-scan antennas or for very long range radars such as  those designed to view extraterrestrial objects. A similar loss must be taken into account when  covcrilig a sc;ircli voltil~lc with a stcp-scatiriing pcrlcil bcain, as wit11 a pllased array," siiicc riot  all regions of space are illilminated by the same value of antenna gain.  1,inliting loss. 
 Depending on the aircraft’s maneuvering capabilities, there is a control profile 1g  acceleration maneuver control line shown as an upward curving line in the upper right  of Figure 5.25.86–8 8 If this conceptual line intercepts the terrain anywhere in range, an  automatic up maneuver is performed. There is also a conceptual pushover line, not  shown in the figure, which causes a corresponding down maneuver. The control pro - file in modern aircraft is automatic because a human pilot does not have the reflexes  to avoid all possible detected obstacles. 
 %% 4HE STABILITY BUDGET ALLOCATED A  
 WAVE CAVITIES  TO ACHIEVE AMPLIFICATION !NOTHER EXAMPLE OF THE LINEAR 
 On reception, the TR tube introduces an insertion loss of about ! to l dB.  The life of a conventional TR is limited by the keep-alive, the amount of water vapor in  the gas filling, and by disappearance, or "clean-up," of the gas due to the gas molecules  becoming imbedded in the walls of the TR tubes.41 The end of life of a TR tube is determined  more by the amount of leakage power which it allows to pass than by physical destruction or  wear.  The keep-alive can be replaced as a supplier of priming electrons in the TR by a radio­ active source, such as tritium, which produces low-energy-level beta rays. 
 Ratliff, P. C., W. Cherry, M. 
 POSITION INDICATOR 00)  DISPLAY 4HUS  $"3 REALLY HAS TWO MEANINGS IN 3!2   THE NAME FOR 3!2 INVENTED BY 7ILEY BEFORE IT WAS CALLED 3!2 AND   THE NAME FOR A 00) 
 Itis important inaparaboloid thatthephaseoftheradiation emitted bythefeedbeindependent of theangle.Theradiation pattern produced bythefeediscalledtheprimary pattem; the radiation patternoftheaperture whenilluminated bythefeediscalledthesecOndtlry pattem. Asimplehalf-wave dipoleoradipolewithaparasitic reRector canbeusedasthefeedfor aparaboloid. Adipoleisoflimitedutility,however, because itisdifficulttoachievethedesired aperture illuminations, ithaspoorpolarization properties inthatsomeoftheenergyincident onthereflector isconverted totheorthogonal polarization, anditislimitedinpower.The opcn-ended waveguide asthefeedforaparaboloid directstheenergybetterthanadipole,and thephasecharacteristic isusuallygoodifradiating inthepropermode.Acircular paraboloid mightbefedbyacircular, open-ended waveguide operating intheTE11mode.Arectangular guideoperating intheTElomodedoesnotgiveacircularly symmetric radiation patternsince thedimensions intheEandHplanes,aswellasthecurrentdistributions inthesetwoplanes, aredifferent. 
 185, pp. 94-120, 2d qtr., 1972.  19. 
 NOFHVIALIZED SENSITIVITY FACTOR K'= K-A/L +• . FIG. 20.9 Geometry for the analysis of elevation errors due to ground reflec- tions in a simultaneous amplitude comparison radar. 
 PATTERNED FEED IS REFLECTED AND ENERGY IS COL 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.76  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 bandpass limiter that precedes the A/D converter. If system instabilities cannot be con - trolled to be less than the system dynamic range, then the system dynamic range should  be decreased. 
 S.: Quantization Requirements in Digital MTI, IEEE Trans., vol. AES-13, pp. 512-521,  September, 1977. 
 REFERENCES  1. Goldman, S.: "Frequency Analysis, Modulation, and Noise," p. 281, McGraw-Hill Book Company. 
 20. A. Roitman, D. 
 Hendry, A., and G. C. McCormick: Deterioration of Circular-polarization Clutter Cancellation in  Anisotropic Precipitation Media, Electronics Letters, vol. 
 (a) SSN = 10. (b) SSN = 100.• = R4th Loss• = R4th + L 0 = Frequency* = El. Angle > 1 deg.- = Noise• = R4th Loss• = R4th -I- L 0 = Frequency* = El. 
 2. B. O. 
 Thustheprfisatleasttwicethemaximum target doppler-frequency. Theleakageofthetransmitter signalintothereceiverproduces thespikeat afrequency foandthespikesatfo±nfpwherenisanintegerandfpisthepulserepetition frequency. Alsointhevicinityoffoistheclutterenergyfromthesidelobes whichilluminate the grounddirectly beneath theaircraft. 
 assumethat10signal-plus-noise pulsesareintegrated alongwith30noisepulses andthatPd=0.90and/If=108.FromFig.2.8b,Lj(40)is3.5dBandL;(lO)is1.7dB,sothat thecollapsing lossis1.8dB.Itisalsopossible toaccount forthecollapsing lossbysubstituting intotheradarequation ofEq.(2.33)theparameter £j(m+11)for£;(n),since£;(n)=1/Li(,,). Theahoveappliesforasquare-law detector. Trunk55hasshownthatthecollapsing loss foralineardetector differsfromthatofthesquare-law detector, anditcanbemuchgreater. 
 I'htrse-pltc~qe plarrirr c~r.rer\~. 'I'he planar array which utilizes phase shifting to steer the bean1 iri  two orttiogotial coorditiatcs is the type of array that is ofrnajor interest for radar applica-  tion because of its inherent versatility. Its application, however, has been limited by its  rcl:ilively llipli coqt. 
 For a ground-based CW radar to operate at maximum sensitivity, two antennas must be employed; this reduces both the spillover and the near-in clutter since no close-in point can be in the main lobes of both transmitting and receiving beams. Moreover, as de- scribed below, spillover cancellation (and hence near-in clutter cancellation) is usually employed. The discussion above assumes that the local oscillator employed in the radar is either derived from the transmitter or locked to it with a servo which has a fre- quency response sufficiently high to cover the doppler and noise band of interest. 
 If biases cannot be kept smaller than the ROU, then at high probabilities of detection,  one prefers single radar association followed by track-to-track association. It is possible to make simple comparisons between the accuracy of detection fusion  as opposed to track fusion for equivalent use of data bandwidth to exchange radar data.  When ROU is plotted as a function of the position gain a, it has the “bathtub” shape  shown by the single radar curve in Figure 7.41. 
 FIGURE 7.39  There are two common methods of fusion data in radar networking: detection-to-track and  track-to-track. ( after W. Bath77 © IEE 2002 ) ch07.indd   47 12/17/07   2:14:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 This value can also be found in standard texts. The power Pt is the peak power of a radar pulse. The average power, Pav, is a better  measure of the ability of a radar to detect targets, so it is sometimes inserted into the  radar equation using Pt = Pav/fpt, where fp is the pulse repetition frequency of the pulse  radar and t is the pulse duration. 
 LIKE  WHICH IS UNLIKELY  !FTER ADDRESSING THE UNSTABLE PULSE 
 Y YY   2AYLEIGH EE)AVVA 
 Geosci. Remote Sens. 2010 ,48, 1505–1517. 
 161 SU-SEL-1Q-Q66, Stanford University, September 1970. 14. Johnson, R. 
 Furthermore, land surfaces are seldom homogeneous either hori- zontally or with depth. Since a true mathematical description of the ground surface appears out of the question, empirical measurements are necessary to describe the radar return from natural surfaces. The role of theory is to aid in interpreting these measure- ments and to suggest how they may be extrapolated. 
 ORDER  THE CLUTTER RETURNS AT (&  FREQUENCIES  AT  MICROWAVE FREQUENCIES THE SMALL 
 Resolution, 20 ft (6 m). (Courtesy Environmental Research Institute of Michigan.) rotation is some minor fraction of the beamwidth. In most cases, the antenna is side-looking, although in some cases the antenna is positioned to an angle off broadside and the system then operates in what is called the squint mode. 
 EX TRACTION OF INFORMATION AND WAVEFORM DESIGN 405  iri tliis hook and is not siriiply related to eitlier tile lialf-power bandwidth or the noise band-  ~vicftli. Iri terrlis of tile ekctivc t~:~riciwicltli, tlie tii~ie-delay error becomes  and tlie range error is 6R = (~12) 67;.  l'lic cKective h;~rielwiiftli ;IS tlcliricci hy Eel. 
 F.: The Story of Radar, Research (London), vol. 6, pp. 434-440, November, 1953. 
 ING FOR RADAR SYSTEMS v 0ROC OF )%%  VOL   PT &  NO   PP n  &EBRUARY    ! &ARINA AND , 4IMMONERI  h#ANCELLATION OF CLUTTER AND EM INTERFERENCE WITH 34!0 ALGORITHM  !PPLICATION TO LIVE DATA ACQUIRED WITH A GROUND 
 400 INTRODUCTION TO RADAR SYSTEMS  of several hundred meters, but accuracies better than a fraction of a meter are practical. Radar  ranges might be as short as that of the police traffic-speed-meter, or as long as the distances to  the nearby planets.  Almost all radars utilize directive antennas. 
 Oliner, A. A., and R. G. 
 PULSE STAGGERING IS USED  THE AMBIGUOUS 
 These radars usually  are on moving platforms. Sidelooking airborne radar (SLAR) . This airborne sidelooking imaging radar pro - vides high resolution in range and obtains suitable resolution in angle by using a  narrow beamwidth antenna. 
 More specific formulations of the maximum-range equation, as given in Chap. 2, also apply to the bistatic radar case. Equation (25.1) is used in this chapter because it more clearly illustrates the utility of constant S/N contours (ovals of Cassini) and other geometric relationships. 
 SCAN  OR # 
 F. B.. M. 
 The mixer itself and the preceding circuits are generally relatively broadband. Tuning of the receiver, between the limits set by the preselector or mixer bandwidth, is accomplished by changing the LO frequency. Effect of Characteristics on Performance. 
 S  IN THE PHASE CODE   AS SHOWN IN &IGURE   "ECAUSE THE  FREQUENCY IS NOT USUALLY A MULTIPLE OF THE RECIPROCAL OF THE SUBPULSE WIDTH  THE CODED SIGNAL IS GENERALLY DISCON 
 ( b) Scintillation imaging result for CkL=1033.(c) Scintillation imaging result for CkL=1034. The scintillation mitigation on point target is performed in Figure 12. The peak loss induced by ionosphere scintillation will weaken the SAR image contrast which makes the dominant scatters hard to select. 
 It is this fre-  quency difference which is proportional to height above  ground.  . XII. 
 Field measurements, however, have shown that many scanning multiple-delay  MTI radar systems fall considerably short of the predicted performance. This occurs  because the IF bandpass limiters have been used to suppress the energy of the residue  spikes that are caused by the limiting action. Later in this section, it is shown that the  use of a binary detection scheme, instead of a drastic reduction of the limit level, can  be used to maintain a clutter rejection performance close to linear theory prediction in  the resolution cells where clutter limiting occur. 
 These requirements are relatively easy to meet in an active system because the same microwave source provides the ref- erence and the transmitter exciter (drive) signal. In semiactive systems, particu- larly in the early-generation systems in which the transmitters were not crystal- controlled, providing a coherent reference posed a significant challenge. The early-generation illuminator transmitters generally employed magnetrons or klystrons as power sources which, while possessing good short-term stability and low near-carrier FM noise, lacked the setability and long-term drift charac- . 
 RATE  MUST BE DETERMINED FROM THE RANGE 
 Knott Tomorrow’s Research (CHAPTER 14) Carlo Kopp Monash University (CHAPTER 5) David Lynch, Jr. DL Sciences, Inc. (CHAPTER 5) Richard K. 
 Multiple Simultaneous Beams. Instead of switching the beams, as described in the preceding paragraph, all the beams may be connected to separate receiv- ers, giving multiple simultaneous receive beams. The transmitter radiation pat- tern would need to be wide to cover all the receive beams. 
 The phase history was selected in a generally asymmetric interval around the peak of the unwrapped phase of the reference function: the possible presence of a squint angle in the true acquired data forces to select the proper doppler phase history to cover all the useful part of the extracted signal phase. As for the range, the thresholding procedure used in the azimuth referencedeﬁnition was limited to the interval in which the signal was above the 10% of the estimated peak of the beam pattern. Once extracted, anyway, the selection of the proper portion of the phase history to be used in the construction of a clean reference was made basing on the phase, as discussed previously (cfr. 
 S3,  pp. 9S4-961, August, 196S.  31. 
 M.: Rain Cancellation Deterioration Due to Surface Reflections in Ground-Mapping  Radars CJsing Circular Polari~ation. IEEE Trutrs.. vol. 
 TRIC CONSTANTS TO THE HOST MATERIAL SHOW DIFFERENT PHASE PATTERNS OF THE REFLECTED SIGNAL (OWEVER  THE PROPAGATION PARAMETERS RELATIVE DIELECTRIC CONSTANT AND LOSS TANGENT  OF THE HOST MATERIAL  THE GEOMETRIC CHARACTERISTICS OF THE TARGET  AND ITS DIELECTRIC PARAM 
 -   - -ETH  h)NDUSTRIAL ASSESSMENT OF THE MICROWAVE POWER TUBE INDUSTRY v $EPARTMENT OF $EFENSE  2EPORT  !PRIL   P    6 'RANATSTEIN  2 0ARKER  AND # !RMSTRON  h3CANNING THE TECHNOLOGY 6ACUUM ELECTRONICS AT THE  DAWN OF THE ST CENTURY v 0ROCEEDINGS OF THE )%%%  VOL   NO   PP n  -AY &)'52%    2!-0 TRANSMITTER AMPLIFIER MODULE  0HOTOGRAPH  COURTESY  OF  2AYTHEON  #OMPANY  .   3/,)$ 
 BIASED AMPLIFIERS ARE VERY SENSITIVE TO ANY DEVIATIONS FROM THE NOMINAL  OPERATING POINT #LASS 
 A. Soofi, and   S. M. 
 I. Skolnik (ed.), McGraw-Hill  Book Company, New York, 1970.  22. 
 See Reference 1.FIGURE 21.37  FCC emission limitsfc greater than 3.1 GHz fc less than 960 MHz Part 15 Limit Frequency in GHz101100UWB EIRP Emission Level in dBm −70−65−60−55−50−45−40 ch21.indd   40 12/17/07   2:51:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 
 UNITS BECAUSE  IT PROVIDES A BETTER PHYSICAL POINT OF VIEW  AN !2%03 USER MAY NOT BE A RADAR ENGINEER BUT A TACTICAL OPERATOR SUCH AS A COMBAT PILOT )N GRAPHICALLY  EXAMINING REFRACTIVE GRA 
  D"C  IS THE LIMIT ON  ) THAT RESULTS FROM OSCILLATOR NOISE 4HE LIMIT  ON )3#2 D"  IS ) D"  PLUS TARGET INTEGRATION GAIN D" &)'52%  #OMPOSITE ADJUSTMENTS AND ADJUSTED PHASE 
 %23 
 OF 
 They can each he applied individually, if desired, to any tracking radar to improve  the accuracy of track.  High-range-resolution monopulse.66 lt has been noted previously in this chapter that the  presence of multiple scatterers within the range-resolution cell of the radar results in scintilla­ tion. or glint. 
 SEA CLUTTER  15.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 wave spectrum considerations.18 It is possible to find examples of data that appear  to follow such behavior while at the same time being expressed as a power law by  brute linear regression, as illustrated in the tower data shown in Figure 15.8.37 This  behavior is not uncommon. FIGURE 15.7  A hypothetical wind-speed dependence of sea  clutter (curved traces) compared with various power laws (straight  lines) ( derived from W. J. 
            .   %,%#42/.)# #/5.4%2 
 Brief Opinions About the Utility of Various Radar Vacuum Tubes.  The types  of RF power sources are mentioned below in no particular order. Grid-Controlled Tube . 
 H.: Properties of Phased Arrays, Proc. I RE, vol. 48, pp. 
 93. S. T. 
 The use of solid-state does not eliminate all the problems of transmitter de- sign, of course. The RF combining networks must be designed with great care and skill to minimize combining losses in order to keep transmitter efficiency . TABLE 5.1 Fielded Solid-State Transmitters *Solid-state replacements of tube-type transmitters. 
 The power spectral density of the filter  response is proportional to the square:   € S(t)~sin12bTt( ) 12bTt        t2 (10.31)  Figure 10.7 shows the function.    Figure  11110.7  Envelope of the receiving signal of SAR.    . 
 MECHANICALLY STEERED 8 
 M.: Far Field Scattering from Bodies of Revolution, Appl. Sci. Research, sec. 
 The same would be true for an array of  dipoles. To avoid ambiguities, the backward radiation is usually eliminated by placing a  renecting screen behind the array. Thus only the radiation O'ler the forward half of the antenna  ( -90° s O s 90°) need be considered. 
 Tl If. EU:CTRONICAI.I.Y STEERED PHASED ARRAY ANTENNA IN RADAR JOJ  the total angular coverage. The handwidth t\/~, or these filters is determined by the frequency  change needed to scan the antenna beam one beamwi<lth, that is  . 
 The energy-storage element is a capacitor. To prevent droop in the pulse shape due to  the exponential nature of a capacitor discharge, only a small fraction of the stored energy is  extracted for the pulse delivered to the tube. In high-power transmitters with long pulses the  capacitor must be very large. 
 Another restriction placed on 1 is that it be small compared with the distance  R from radar to target. Furthermore, R, RR, -- R. The cross sections of the two targets are  assumed equal and are designated go. 
 IGARSS04 ,   vol. II, pp. 800–802, 2004. 
 £n°Ón  2!$!2 (!.$"//+  SUCH RADARS FROM THEIR MORE COMMON COUNTERPARTS DESCRIBED IN THE PRECEDING  PARAGRAPH #OHERENT DUAL POLARIZATION HAS NOT BEEN EXPLOITED IN ORBITAL 3!2S ALTHOUGH IT IS STANDARD PRACTICE IN %ARTH 
 64 COSX4   
         
 TIVE PROCESSING  &ASTER SCANNING RADARS USED FOR SAMPLING RAPIDLY EVOLVING STORMS  REQUIRES SPECTRUM ANALYSIS TECHNIQUES THAT USE SHORT DWELL TIME DATA SETS OF MANY FEWER )1 DATA SAMPLES -ODERN SPECTRUM ANALYSIS TECHNIQUES SUCH AS THE "URG MAXIMUM ENTROPY  AND THE #APON MAXIMUM LIKELIHOOD ESTIMATORS ALLOW USING SHORT DWELL  SAMPLED DATA TO OBTAIN STABLE SPECTRUM ESTIMATORS 4HESE TECHNIQUES BELONG TO THE GENERAL CLASS OF AUTOREGRESSIVE !2  ESTIMATORS WHEREBY THE OBSERVED DATA ARE MOD 
 The cos (P/2) frequency reduction term has little effect in KeIl's pseudo- monostatic region, O < P < ~ 5°, since a 5° bistatic angle corresponds to less than 0.1 percent shift in wavelength. At (3 > 5° the change in radiation properties from discrete scattering centers is likely to dominate any cos (3/2) frequency re- duction effect.41 Thus the cos (p/2) term is often ignored. Both versions of the equivalence theorem are valid when the positions of the transmitter and receiver are interchanged, given that the target-scattering media are reciprocal. 
 An example of the elevation angle error at low angles is shown in Fig. 5.16 for a target at  constant height.43 At close range the target elevation angle is large and the antenna beam does  not illuminate the surface; hence the tracking is smooth. At intermediate range, where the  elevation angle is from 0.8 to as much as six beamwidths, the surface-reflected signal enters  the radar by means of the antenna near-in sidelobes. 
 Remote Sens. Lett. 2013 ,10, 617–621. 
 A. Fabrizio, Y. I. 
 Some important phase shifters, however, are nonreciprocal. These  must have different control settings for reception and transmission. A phase shifter should he  able to change its phase rapidly, be capable of handling high power, require control signals of  little power, be of low loss, light weight, small size, have long life, and be of reasonable cost. 
 TION -!23)3 HAS PERFORMED AS INTENDED   WITH EARLY RESULTS FROM THE POLAR LAYERED  DEPOSITS  FOR EXAMPLE 3(!2!$ 4HE 3HALLOW 2ADAR SOUNDER WAS DESIGNED TO COMPLEMENT -!23)3  )N GENERAL TERMS  IT HAS HIGHER RESOLUTION AT A HIGHER FREQUENCY  DESIGNED TO PROVIDE SHARPER DIFFERENTIATION OF THE UPPER SEVERAL HUNDRED METERS OF THE SURFACE OF -ARS 3(!2!$ TRANSMITS A  
 An important design parameter for reflector antennas is the ratio of the focal length  .(to the antenna diameter D, orflD ratio. The selection of the properflD ratio is based on both  meclianical arid electrical considerations. A smallflD ratio requires a deep-dish reflector, while  a large j;lD ratio requires a shallow reflector. 
 In fact, when either the  jamming or clutter statistics cannot be estimated independently of one another, it  becomes difficult to design an effective spatial adaptive filter for jamming rejection  or a temporal adaptive filter for clutter mitigation since the presence of one con - taminates the estimation process for the other.116 This problem is most accentuated  when the clutter-to-jamming ratio approaches unity; in which case, the cascade of a  spatial and a temporal adaptive processors may perform poorly. In such situations,  a joint two-dimensional adaptive filtering in doppler and angle domains represents  a means to cancel the composite disturbance (i.e., the superposition of jamming  and clutter) jointly rather than sequentially.117 The performance advantages of two- dimensional adaptivity shall be traded-off with the computational cost. To reduce  the computational load, different computational strategies may be devised, for  example, by calculating the adapted two-dimensional weights at a rate lower than  the input data and applying them to the radar snapshots at their natural rate. 
 The inverse SAR is a method of reconstructing a high-resolution two- dimensional EM intensity image of moving targets (e.g., ships, aircraft) in the range  and cross-range (doppler) domains. ISAR imaging is important in military applications  such as target recognition and classification (since it can usually recognize the class of  target) that can also be used to cue weapon systems. The need for coherent countering  of these imaging sensors is a high priority for EW. 
 It is sometimes called  a gyro-oscillator  to differentiate it from a gyro-amplifier  that utilizes several resonant  cavities or a traveling wave circuit to operate as an amplifier. The gyro-amplifier that  employs several resonant cavities is called a gyroklystron , and when a traveling-wave  circuit is used, it is called a gyro-traveling-wave-tube , or, more commonly, gyro-TWT .  There is also a gyrotwystron  with the resonant output cavity replaced by a TWT cir - cuit so as to achieve greater bandwidth than can be obtained with a resonant cavity. 
 Other conditions are as in Fig. 20.10. TPS-59/GE-592/FPS-117 solid-state radar series.27 The problem with conven- tional sum-delta monopulse in a surface multipath environment is that the delta-beam peak response is in the direction of the indirect-path reflection. 
 FREQUENCY AUTOCORRELATION FUNCTION IS USED BY 3PAFFORD 4HE SIGNS ASSOCIATED WITH  S  AND FD  WITHIN THE INTEGRAND ALSO DIFFER IN THE LITERATURE 4HE STANDARDIZED DEFINITION PROPOSED BY 3INSKY AND 7ANG IS  USED IN THIS CHAPTER. 
 is the  wavelength in centimeters. Im ( K) is the imaginary part of K, and K is a factor which  depends upon the dielectric constant of the particle. At a temperature of l0°C, the value of  Im ( -K) for waler is 0.00688 when the wavelength is 10 cm (S band) and 0.0247 for 3.2-cm  wavelength (X band).71 Equation (13.28) is a good approximation for rain attenuation at  S-band or longer wavelengths. 
 When independent analy - ses of the Clementine  data failed to reproduce the original result,106,107 considerable  controversy was generated as well. Discovery and/or verification of polar ice deposits  on the Moon emerged as a major objective of NASA’s exploration program,108 and if  proven, would be an essential resource for habitable outposts at the Moon. Radar Exploration for Planetary Ice. 
 2. Well-developed technology.1 . Very popular with the advent of high-speed digital devices. 
 ATIC SURFACE DEFORMATION &OR MANY REFLECTORS  A MESH IS ATTACHED TO A METAL OR COMPOSITE BACKING STRUCTURE &OR SPACEBORNE DEPLOYABLE REFLECTORS  THE MESH IS TYPI 
 CM WAVELENGTHS )MAGING RESOLUTION WAS  ^ KM %ACH  KG  SPACECRAFT WAS A CYLINDER  M IN LENGTH 4HE SYNTHETIC APERTURE RADAR ANTENNA WAS A   r  METER PARABOLIC CYLINDER REFLECTOR  POWERED BY AN  
 If low­ angle coverage is desired, the radar antenna height should be high and the wavelength of the  radiated energy small. The antenna pattern lobes caused by the presence of the ground might  sometimes be of advantage when the longest possible detection range is desired against low­ altitude targets and where continuous coverage is not required.  The simple form of the radar equation (Eq. 
 Consequently, relatively shortpulse lengths, about 0.1 microsecond, must be used for close-in ranging. Many radar sets are designed for operation with both short and long pulse lengths. Many of these radar sets are shifted automatically to the shorterpulselengthonselectingtheshorterrangescales.Ontheotherradarsets,theoperator must select the radar pulse length in accordance with the operatingconditions. 
 2, pp. 210-219), the maximum improvement factor / against zero-mean clutter with a gaussian-shaped spectrum, for different imple- mentations of the finite-impulse-response binomial-weight MTI canceler (see Sec. 15.7), is /i ~ 2Jr^-J (15.9)\2irac/ 7'~ 2^)4 (15-10) /3~^V (15-11)3\2irac/ where I1 is the MTI improvement factor for the single-delay coherent canceler; I2 is the MTI improvement factor for the dual-delay coherent canceler; J3 is the MTI improvement factor for the triple-delay coherent canceler; crc is the rms fre- quency spread of the gaussian clutter power spectrum, in hertz; and/r is the radar repetition frequency, in hertz. 
 Electron., pp. 286-290, May 12-14, 1958. 35. 
 The imaging quality parameters of the strong scattering are shown in Table 3. 148. Sensors 2019 ,19, 2921 x(m) x(m)   (a) The ArcSAR Imaging on the reference plane  (b) The ArcSAR Imaging by proposed method   Figure 22. 
 ALARM RATE  INVESTIGATED BY &INN AND *OHNSON  )F THE NOISE HAS A 2AYLEIGH DEN 
 The scattering cross section ofthe droplets responsible forthe signal return varies asl/k4. Return from alarge storm center also varies linearly with pulse length and with beamwidth, but these parameters are restricted to relatively narrow regions and the variation ofcross section with wavelength istherefore the controlling relation. Dependable operational data arerather limited butthefollowing results appear tobeestablished: (a),Atawavelength of3cm, cloud return in some regions frequently obscures alarge fraction ofthe coverage area and seriously restricts the use ofthe equipment; (b)reports ofthis difficulty at10cmareless frequent, and information fur- nished onstorm centers isvaluable fordirection ofplanes around dangerous regions; (c)aswavelength isincreased, less ofthecover- age area isobscured bycloud return; but storm areas that are dangerous toplanes may fail toshow onthe radar atthe longer wavelengths. 
 ILY AT CHARACTERIZATION OF THE -ARTIAN IONOSPHERE  DURING DAYLIGHT CONDITIONS FROM  ALTITUDES BELOW  KM 4HE RADAR IS OPERATED AS A STEPPED 
 This is sometimes called the Bragg backscattering reso11a11ce condi­ tion because of its similarity to the X-ray scattering in crystals as observed by Bragg.2 Thus  the radar is responsive only to those water waves which satisfy Eq. ( 13.13 ). An X-band radar  (l = 3 cm) at zero degrees grazing angle would backscatter from water waves of length 1.5 cm. 
      . 
 25, pp. 377-445, 1908. 14. 
 Figure 25.36 a shows a single-stage CIC decimator. The filter contains an integrator  stage consisting of a single sample delay and an adder, followed by a comb stage with  a D-stage shift register (denoted by the Dt  block) and a subtractor. The comb filter gets  its name because its frequency response looks like a rectified sine wave and resembles  the teeth of a comb. 
 III. It may be noted that since ASV Mk. VI had 7 dB more power, the noise-limited range might have been expected to be about 50% greater, even without accounting for reduced microwave losses of the later systems. 
 12. Susskind, C.: "The Birth of the Golden Cockerel: The Development of Radar," in preparation  13. Price, A.: "Instruments of Darkness," Macdonald and Janes, London, 1977. 
 When the range to the target is relatively short and tests must be performed over  a wide range of frequencies, it is sometimes advantageous to attempt to defeat the  ground-plane effect. One option is to install a berm shaped like an inverted V running  between the radar and the target. The purpose of the berm’s slanted top is to deflect  the ground-reflected wave out of the target zone. 
 316 ANTENNAS, SCANNERS, ANDSTABILIZATION [SEC. 923 sofarasthe aerodynamics isconcerned, but limits the rearward view. This space, too, isdesirable forthelocation ofcertain crew members and ofthebombsight. 
 ABLE TRACKING GAINS EG  LARGER  GAINS AT THE BEGINNING OF THE TRACK AND LARGER GAINS AFTER  MISSED DETECTIONS OR WHEN THE RANGE TO THE TRACK DECREASES  MAKING ANGLE NOISE LESS OF AN ISSUE  ! SYSTEMATIC METHOD FOR CALCULATING THE GAINS DEPENDING ON THE SITUATION IS THE  &)'52%  %XAMPLE OF THE TUNING OF AN  @ 
  )NDIA &R       +A 9ES  #RYO3AT 
  BOTH SINGLE 
 The use of digital delay lines requires  that the output of the MTI receiver phase-detector be quantized into a sequence of digital  words. The compactness and convenience of digital processing allows the implementation of  more complex delay-line cancelers with filter characteristics not practical with analog  methods.  One of the advantages of a time-domain delay-line canceler as compared to the more  conventional frequency-domain filter is that a single network operates at all ranges and does  not require a separate filter for each range resolution cell. 
 The following shows the steps of Cat mapping to produce random sequence and construct observation matrix: (1) Produce chaos sequence according to Cat mapping equation, and the mapping is deﬁned as: /bracketleftBigg xn+1 yn+1/bracketrightBigg =/bracketleftBigg 1 a ba b +1/bracketrightBigg/bracketleftBigg xn yn/bracketrightBigg (mod 1 ), (32) where, (mod 1 )represents the integer whose real number is casted out, namely xmod 1=x−⌊x⌋.xn sequence is selected to construct the needed deterministic random sequence. (2) For using the chaos sequence construction Φrin stable area, cast out the gvalue in front of the sequence. It means to select xg+1as the starting point of the sampling. 
 Entirely aside from custom, there are several valid arguments favoring the use of 6 dB parameters. As indicated in Table 3.2, the optimum bandwidth-time product for detection of a pulse in white gaussian noise, with each defined at the 6 dB points, does not deviate significantly from unity for most practical func- tions. The 3 dB or energy definitions yield widely variable optimum bandwidths, dependent upon the shape of the pulse and the bandpass of the filter; there can be no quick estimation of optimum bandwidth if these parameters are utilized. 
 MOVING TARGETS -ANY YEARS AGO  #RONEY   SHOWED THAT SIGNIFICANT IMPROVEMENTS IN DETECTING SMALL TARGETS IN SEA CLUTTER COULD BE OBTAINED BY ENSURING THAT INTEGRATION WAS PERFORMED AT INTERVALS LONGER THAN THE DECOR 
 4.13. When feedback loops are  'I'  Figure 4.13 Canonical-configuration comb filter. (Afrer White and Ruvin,l IRE Natl. 
 The disadvantage with detecting targets in the grating lobes is  thiit the angle measurement can be ambiguous. There are methods, however, for resolving  these ambig~ities."~  Instead of thinning elements, the number of phase shifters can be thinned.'" That is,  some of the phase shifters in the array can be useci to adjust the phase of more than one  element, so that the number of phase shifters is less than the number of elements. A 50 percent  saving in the total number of phase shifters might be.had. 
 130. Hansen, R. C.: Conformal Arrays, J\ficrmW11·e J., vol. 
 On a ship,  for example, an unstabilized antenna with its beam parallel to the deck plane will have its  coverage shortened for surface targets since the beam will be looking into the water or up in  the air as the ship rolls or pitches. In addition to degraded coverage, the measurement of the  angular position with an unstabilized antenna can be in error unless the tilting of the platform  is properly taken into account.  Stabilization of the antenna adds to the weight and size of the radar, but it is necessary in  many applications of radar on ships and aircraft. 
 142  Clutter map. 184  in MTD. 127  Coaxial magnetron, 193- 198  Coaxitron, 21 3  Coded pulse, 428-431  Coherent detector, 385-386  Coherent reference, in MTI, 102  Coho, 105, 141  Cold-cat hode emission, 2 10  Collapsing loss. 
 thewavescattered fromtheseasurfaceareoutofphaseandproduce destructive interference. (Theinterference regionisnotwelldefined atthehighermicrowave frequencies plotted in Fig.1.\..1.)Theangular regionhetween theinterference regionandthequasi-specular region istheplateau, orcliflil.~e,reyilm.Thechiefscatterers arethosecomponents oftheseathatare ofadimension comparable totheradarwavelength (Braggscatter). Scattering inthisregion i<;similartothatfromaroughsurface. 
 LAUNCHER  4%,  &IGURE  B SHOWS THE FOCUSED IMAGE OF THE TRACTOR 
 Prcngarnan: integration and Automation of Multiple Co-located Radars,  Itrrc~rnl~tiottol Cor?/i.ri~trcc~ R/11),1 R-77. Oct. 25 -28, 1977, pp. 
   CONDUCTOR ,$-/3  TRANSISTOR IS BEGINNING TO SUPERSEDE THE SILICON POWER "*4 AS A REPLACEMENT DEVICE  ESPECIALLY AT THE 6(&  5(&  AND , 
 WAVE 
 Figure 14.28 illustrates the RCS reduction available through shaping. The plotted  curves are based on theory and measurements and show how the nose-on (axial) RCS  varies with the electrical size of each of the six rotationally symmetrical metallic bod - ies shown in Figure 14.29. The diameters and projected areas of the objects are identi - cal, and their volumes differ at most by a factor of 2. 
 vol. AP-13, pp. 878-882, Nov., 1965. 
 DAY REPEAT PERIOD 3INCE THIS IS NOT A SUN 
 Digital Waveform Generation.  Figure 8.26 shows a digital approach46 for gen - erating the radar waveform. The phase control element supplies digital samples of the  in-phase component I and the quadrature component Q, which are converted to their  analog equivalents. 
 The secondary antenna aper- ture was similar to the primary aperture except that it rotated about an axis nor- mal to the aperture. This produced a second fan beam which was tilted from the vertical plane. The two beams might be powered by the same or separate trans- mitters, but each beam had its own receiver. 
 FIELD  AMPLIFIER  THEY HAVE A LARGER DYNAMIC RANGE #OMPARED TO A 474  THEY ARE CAPABLE OF HIGHER PEAK AND AVERAGE POWERS  AND THEY ARE LESS SENSITIVE TO VIBRATIONS 4HE 2USSIAN COMPANY KNOWN AS &EDERAL 3TATE 5NITARY %NTERPRISE  20# )STOK   USUALLY SHORTENED TO )STOK  HAS BEEN PRODUCTIVE IN THE DEVELOPMENT OF -"+S FOR RADAR !T 8 BAND  THEY REPORT AN -"+ WITH  BEAMLETS PRODUCING  K7 PEAK POWER   K7 AVERAGE POWER   BANDWIDTH  AN ANODE VOLTAGE OF  K6  WITH A MAG 
 Such plots can be used to  determine the maximum frequency that will propagate to a given range; in most  cases, the optimum frequency is just below the maximum frequency. For the little  tables shown in Figure. 20.24 and 20.25, FC is the critical frequency, in megahertz;  HC is the height of maximum ionization or the nose of the parabola, in kilometers;  and YM is the semilayer thickness, in kilometers. 
 A.: Application of Graphite Composites to Future Spacecraft Antennas, AIAA Pap. 76-328, Sixth Commun. Satellite Syst. 
 EARTH 
 POWER 
 The direct and retlccted  waves interfere to produce a lobed radiation pattern similar to that described for the plane  Free-space coveroge contour 1  ., , ! Range, nml  (a) horizontal polarization  Figure 12.4 Example of a vertical-plane coverage diagram for (a) horizontal polarization and (h) vertical  polarization. Frequency = 1300 MHz, antenna height = 50 ft, antenna vertical beamwidth = 12" wit11  beam maximum pointing on the horizon, sea surface with 4 ft wave-height and a free space  range = 100 nmi.  446INTRODUCTION TORADAR SYSTEMS elevation angleofarrivalbycomparing theamplitudes ofthesignalsreceived attwodifferent beamelevation angles(lobecomparison) cangiveerroneollsandambiguollsmeasurements at lowangles:u5Elevation errorsnearthegroundmaybeconsiderably reducedinmagnitude andtheambiguities eliminated bysurrounding theradarwithametallicfencetoremovethe ground-reflected wave.ThefencereplacesthegroLlnd-reflected wavewithadiffracted waveof lesserimportance. 
 When the output se­ quence of an n-stagc shift register is of period 2" -1, it is called a maximal le11gtl1 sequence, or  m-sequence. These have also been called linear recursive sequences (LRS), pseudonoise (PN)  sequences, and binary-shift-register sequences. Although the sequence is a series of zeros or  ones, for application to the phase-coded pulse-compression radar the zeros can be considered  as corresponding to zero phase and the ones to n radians phase. 
 Practical considerations (see Chapter 4 of Farina34 for a detailed analysis) often  limit the SLC nulling capabilities to a JCR of about 30 to 40 dB, but their theoreti - cal performance is potentially much higher. Adequate cancellation of the directional  interference is obtained if the receiving channels are properly matched in amplitude  and phase across the radar receiving bandwidth. This condition is necessary to attri - bute the amplitude and phase differences measured across the channels only to the  nature (power and DoA) of the impinging interference. 
 I\ssume initially thatthetwoforward andtwobackward beamsaresymmetrically disposed aoouttheaxisoftheaircraft. Iftheaircraft's velocity isnotinthesamedirection astheaircraft heading, thedoppler frequency inthetwoforward beamswillnotbethesame.Thisdifference infrequency maybeusedtogenerate anerrorsignalinaservomechanism whichrotatesthe antennas untilthedoppler frequencies areequal,indicating thattheaxisoftheantennas is alignedwiththegroundtrackoftheaircraft. Theangular displacement oftheantenna from theaircraft heading isthedriftangle,andthemagnitude ofthedoppler isameasure ofthe speedalongthegroundtracle Theuseofthetworearward beamsinconjunction withthetwoforward beamsresultsin considerable improvement inaccuracy.Iteliminates theerrorintroduced byverticalmotionof theaircraftandreducestheerrorcausedbypitching movements oftheantenna. 
 Voltages substantially higher than thenominal design value cause aflash-over intheswitch. The hy- drogen thyratron, on the other hand, isatrue thyratron. Its grid has complete control oftheAnode Grid Cathoae FIG.10.41.—Hydrogen thyraton. 
 Skolnik . CHAPTER  ONE  THE NATURE OF RADAR  I.I INTRODUCTION  Radar is an electromagnetic system for the detection and location of objects. It operates by  transmitting a particular type of waveform, a pulse-modulated sine wave for example, and  detects the nature of the echo signal. 
 This creates a tilted phase front across the array, which causes the  beam to squint to an angle that is frequency dependent. Individual manufacturers pro - duce radar systems operating over a restricted band, much less than the overall radar  band, which removes any need for individual squint compensation when magnetrons  are replaced. The required sidelobe performance is not demanding (Table 22.3), and  so simple aperture distributions, such as pedestal-based cosine squared, are common. 
 The lobe at p = q = 0 is the main beam. A triangular grid is more efficient for  suppressing grating lobes than a rectangular grid,44 so that for a given aperture size,  ch13.indd   17 12/17/07   2:39:39 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Inspiteofthelimitations oftheconventional CRTdisplay, itisalmost universally usedforradarapplications. Manyofitslimitations canbeovercome, but sometimes withasacrifice insomeotherproperty. Theabilityofanoperator toextractinformation efficiently fromaCRTdisplaywill dependonsuchfactorsasthebrightness ofthedisplay, densityandcharacter oftheback­ groundnoise,pulserepetition rate,scanrateoftheantenna beam,signalclipping, decaytime ofthephosphor, lengthoftimeofblipexposure, blipsize,viewingdistance, ambient illumina­ tion,darkadaptation, displaysize,andoperator fatigue.Empirical dataderivedfromexper­ imentaltestingofmanyofthesefactorsareavailable.28•29 Therehasbeenmuchinterestinapplying solid-state technology asaradardisplayto replacethevacuum-tube CRT.Although thelight-emitting diodehasbeentoocostlyand complex tobeageneralreplacement fortheCRT,itmightbeappliedwhenrequired to1isplay limitedinformation without thedisplayoccupying excessive space,suchasintheDistance fromTouchdown Indicator (DFTI) usedinaircraft control towerstomonitor landing aircraft. 
 21-23, 1975, IEEE Publication 75 CHO 938-1 AES.  24. Cook, C. 
 The use of digital delay lines requires  that the output of the MTI receiver phase-detector be quantized into a sequence of digital  words. The compactness and convenience of digital processing allows the implerfientation of  more complex delay-line cancelers with filter characteristics not practical with analog  met hods.  One of the advantages of a time-domain delay-line canceler as compared to the more  conventional frequency-domain filter is that a single network operates at all ranges and does  not require a separate filter for each range resolution cell. 
 Inform. Theory , vol. IT-6,   pp. 
 2-10, MarchIApril, 1967. r  30. Golomb, S. 
 It is intended  that the results of surface truth investigations will be the  basis for new table entries.  Automatic Gain Control Corrections  Adjustments to the automatic gain control data include  a correction for height variation that affects signal  VATT tJ.H = Co + c1 x VATTc  tJ.AGC dO + d1 x VA TTc  tJ.SWH = a1 x(VATTc -bO) ~  (off-nadir)  tJ.H  (SWH/O  tJ.AGC  (SWH /~)  tJ.SWH  (SWH /~)  AGC = automatic gain control  Figure 7-Wave-height/attitude·dependent correction factors for  the height (tJ.H), automatic gain control (tJ.AGC), and significant  wave height (tJ.SWH) are derived from a voltage proportional to  attitude (VATT), and the off·nadir pointing angle (~) is estimat·  ed. The particular set of coefficients used will depend on the  observed wave height. 
 An equation for  detecting a target in this type of clutter background could be derived, but it is a situation not  often found in practice.  In describing the geometry or surface clutter, the incidence angle and the depression angle  are sometimes used instead of I he grazing angle. These are shown in Fig. 
 This is the processing done after the detection decision has been made. Automatic tracking (Chap. 8) is the chief example of data processing. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.54  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 other information such as target altitude.140 (Estimates of aircraft target altitude are  very useful, but skywave radar has not proved to be a reliable means of obtaining  accurate estimates.) The problem of converting from radar coordinates to geographical coordinates is  referred to as coordinate registration (CR).  Dozens of CR techniques have been explored,  including (i) inference from a regional ionospheric model, (ii) deploying a network of  repeaters or beacons in the radar footprint, (iii) correlating coastlines with land clutter—   sea clutter boundaries in the radar data, (iv) correlating other parameters such as scatter - ing coefficient, (v) using known target information such as reports from ships and com - mercial airline flights, and (vi) registering airports, where tracks originate or terminate. 
 The first target (termed the reference target ) is located at the origin of the  delay-doppler plane with zero relative time delay and zero doppler frequency, and the  second target is at relative time delay t  and doppler frequency fd. The relative time delay  is positive when the second target is farther in range than the reference target and the  doppler frequency is positive for an incoming target. The matched-filter output power  for the reference target is proportional to the ambiguity function and is given by  Pref = Ψu (0,0) = 1 (8.57) The matched filter output power for the second target, evaluated at the peak of the  reference target, is   P2 = Ψu (t, fd) (8.58) The second target is unresolved from the reference target at locations in the delay- doppler plane where Ψu(t, fd) ≈ 1. 
 Rabus, M. Eineder, A. Roth, and R. 
 Moreover, the mobility of the aircraft permits  longer term observations of rapidly moving but long-lived storms and cloud systems,  thereby allowing more complete studies of evolution during various phases of the  system.170 NCAR’s Eldora airborne doppler radar system,171 shown in Figure 19.12, consists  of two slotted waveguide fixed-beam antennas mounted in the tail of the P-3 air - craft, which is operated by the Naval Research Laboratory and covered by a rotating FIGURE   19. 11 Rapid-DOW (Doppler on Wheels) is a mobile X-band radar  that uses six simultaneous beams to cover a volume of atmosphere in a much  shorter volume coverage time than a mechanically scanned single beam radar.  This rapid update scan is important for measuring violent convective storms, espe - cially tornadoes as shown in photo. 
 24 CryoSat altimeter, 18.42 to 18.43 D D region, 20.14 Dällenbach layer, 14.37 to 14.38 Data link, missile, 5.26 Data links, in MFAR, 5. 24 to 5.27 Data processing, 1.3 dBZ, 19.5 to 19.6 DC operation of CFA, 10.17, 10.24 Deceptive ECM (DECM), and ECCM, 24.6 to 24.7, 24.40 and tracking radar, 24.41 to 24.42 Decimation, 6.41 to 6.42 Decimation filters, 25.28 to 25.32 Decoys, 24.6, 24.8 Delta-Sigma converters, 6.36 Depressed collector, 10.10 Detection acceptance, 7.25 to 7.26 Detectors batch processor, 7.8 to 7.11 bi nary integrator, 7.7 to 7.8, 7.12 to 7.13 M-out-of-N, 7.7 to 7.8 moving window, 7.4 to 7.7 nonparametric, 7.17 to 7.18 optimal, 7.2 to 7.4 practical, 7.4 to 7.11 rank, 7.17 to 7.18 Dicke fix, 24.33, 24.35 Differential reflectivity, 19.18 Diffraction, 26.5 Digital beamforming, 13.8, 13.56 to 13.57 multiple beams, 25.17 to 25.19. Digital downconversion (DDC), 6.41 to 6.42, 6.44 to 6.45, 25.6 to 25.15 Digital filters, 25.26 to 25.32 Digital pulse compression, 25.19 generation of, 8.28 to 8.30 Digital receiver, 6.40 to 6.46 block diagram, 25. 
 RESPONSE CHARACTERISTICS OF TWO  SERVOSYSTEMS AND B  THEIR CORRESPONDING TIME RESPONSE TO A STEP INPUT. °Óä  2!$!2 (!.$"//+  °xÊ /, 
 17.10a. The regenerative tracking assists greatly inovercoming errors inthe modu- lators byrectifying the modulated alternating current with aphase- sensitive detector and using this result tocontrol the tracking delay circuit. Thus the amplitude ofthe modulated alternating current (which isthequantity ofprimary interest) isforced tovary inthesame manner asthe delay inthe signal pulse, regardless oferrors inthe comparison circuits, themodulator, any amplifiers, etc. 
 TUDE STEPS WILL CAUSE QUANTIZATION LOBES 3ECTION  &)'52%   #OMBINATION OF SUBARRAYS TO FORM SUM AND DIFFERENCE CHANNELS A  COMBINING OPPOSITE  SUBARRAYS AND B  COMBINING SUBARRAYS AFTER AMPLIFICATION . 
 Extensive techniques are usually de- . vised to minimize repetitive calculations through the use of arrays containing the unit vectors in the pattern directions of interest, polarization vectors for those directions, and symmetry. The literature contains many articles showing how geometric theory of diffrac- tion (GTD) techniques can be used to compute reflector patterns.7'39 The prob- lem one encounters with GTD is in generalizing the situation, such as an irregular antenna outline. 
 Consequently LCFAR is dependent on the Pfa and on the CFAR -parameter settings and thus also  on the length of the CFAR -window. According to the above Figure, the CFAR loss LCFAR of  the individual CFAR methods in dependence on the Pfa for a CFAR- window length of a p- proximately 120. The CFAR loss of the MAMIS -CFAR is higher than that of the CASH - CFAR and LCFAR of the CA -CFAR is insignificantly smaller than that of the CAGO -CFAR. 
 Y . T. Lo and S. 
 21. W. E. 
 R. W. Larsen and R. 
 ch05.indd   42 12/17/07   1:27:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 
 90.Howard. D.n.,SM.Sherman. D.N.Thomson. 
 LIKE REFLECTOR FEEDS TO ACHIEVE ELEC 
 If there were no theoretical restrictions, the ideal ambiguity diagram  would consist of a single peak of infinitesimal thickness at the origin and be zero everywhere  else, as shown in Fig. 11. 7. 
 At 10 MHz the night and day levels are the same; below 10 MHz the noise decreases with decreasing frequency in daytime and increases at night. Above 10 MHz day- time levels are greater than those at night. These effects can be partially ex- plained by the very lossy long-range paths in day that attenuate the long-range noise at the lower frequencies and by there being few or no sky-wave paths to noise terrestrial sources at the higher frequencies at night. 
 6. Moskowitz, L. I.: The Wave Spectrum and Windspeed as Descriptors of the Ocean Surface, N,,val  Research Laboratory Report 7626, Washington, D.C., Oct. 
 24.66  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 170. A. Farina and P. 
 C. Daley, “Variation of the NRCS of the sea with increas - ing roughness,” J. Geophys. 
 YD RANGE STEP &)'52%     %ARLY 
 48. Tucker, D. G.: Detection of Pulse Signals in Noise: Trace-to-Trace Correlation in Visual Displays, J. 
 Insuch acase, asshown inFig. 11.8d, thetwo wires” become broad busbars with only asmuch ofthewide side ofthe guide given over tostubs asisrequired bythe now shorter wavelength. However, wavelengths greater than twice the broad dimension cannot bepropagated because then the stubs become less Waveguide Handbook, Vol. 
 Consider the hysteresis loop, or B-H curve, of Fig. 8.11. This is a plot or the magnetization  (gauss) as a function of the applied magnetic field (oersted) for a toroid-shaped section of  ferrirnagnetic material. 
 With this in mind, the stationary phase result for a circular cylinder is  sq q=kak k 22sin( sin ) sin (14.16) where a is the radius of the cylinder,  is its length, and q is the angle off broadside  incidence. Equation 14.16 includes only the contribution from the curved side of the FIGURE 14.18  PO patterns of the RCS of a square plate,   a disk, and second square plate ch14.indd   23 12/17/07   2:47:17 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Dependence onburnthrough asa majorFCCM tacticisquestionable. Itshould beusedwherecost-elTectivc andwherethe reduction indatarateistolerable. Impulsive noise,thatcanshock-excite the"narrow-band" radarreceiver andcauseitto ring,canbereduced withtheLambnoise-silencing circuit,53 orDickefix.54Thisconsists ofa widebandIFfilterincascade withalimiter, followed bythenormalIFmatched filter.The. 
 Typical ray diagrams forcosecant-squared antennas are shown inFigs. 9.2, 9.10, and 9“37. Ifthe antenna isstabilized, the angles will have to bechecked throughout the range ofstabilization. 
 12.8). The principle ofstagger tuning can becarried further. Staggered triples (three different frequencies) areinfairly common use, and stag- gered n-uples are practicable forwideband amplifiers. 
 Con- siderations here are that the straddling loss of the filter bank be minimized (this dictates the location of the peak), that the response to chaff at 0.8 doppler be down 46 dB, and that the mismatch loss be minimized. Minimizing the mismatch loss is accomplished by permitting the filter sidelobes between 0.3 and 0.8 to rise as high as needed (lower sidelobes in this range increase the mismatch loss). The second zero-doppler filter is the mirror image of this one.MISMATCH LOSS . 
 MODULATION   /UT 
 3. Equal energy is transmitted in both pulses. A 2:1 imbalance sacrifices only 0.2 dB  of the benefit at 90% PD. 
 POLARIZED SCATTER IS LOWER THAN LIKE 
 FOLLOWING LOGIC &INALLY  THE CHAPTER CONCLUDES WITH A DISCUSSION OF SENSOR INTEGRATION AND RADAR NETTING  INCLUDING BOTH COLOCATED AND MULTISITE SYSTEMS Ç°ÓÊ 1/" / Ê 
 E. A. Wan, R. 
 MOVING TARGET REJECTION -EASURES RADIAL VELOCITY ,ESS RANGE ECLIPSING THAN IN HIGH 
 Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 8.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 APPENDIX Signal Analysis Summary.68–70 Table 8.10 is a summary of signal analysis defi - nitions and relationships. Table 8.11 shows Woodward’s Fourier transform rules and  pairs.69 These relationships simplify the application of signal analysis techniques. 
 389-404, 1956.  54. Retts, F., D. 
 Taylor, “Receivers,” Chap. 3 in Radar Handbook , 2nd Ed., M. I. 
 Siegel: "Methods of Radar Cross-Section Analysis." Academic f'scss.  New York. 1968, chap. 
 Δtr is the measurement accuracy for the edge  triggering.  With that yields the range accuracy:   € ΔR=c0⋅Δtr/2 (5.11)  The other equations from above can be applied in analogous way.   5.3 Range Resolution of Two Neighbouring Targets   By the term resolution it is understood the differentiation of targets, which are in very close pro x- imity to on another, as shown in Figure 5.3     Figu re 5.3  Echoes of two neighbouring objects. 
 SCAN AND CUMULATIVE PROBABILITY OF DETECTION. {°{n  2!$!2 (!.$"//+  #LUTTER 
 IOH.Shelton. J.P..Jr..andK.S.Kelleher: RecentElectronic Scanning Developments. CalifPmc.,Fourth NIIII.('(}IIf'. 
 I. Marcum, “A statistical theory of target detection by pulsed radar,” IEEE  Transactions on  Information Theory,  vol. IT-6, pp. 
 The diode mixers would be mounted at equal distances in each of the collinear arms.) The  two diode mixers should have identical characteristics and be well matched. The IF signal is  Figure 9.2 Principle of the balanced mixer based on the magic T. Magic T  H LO RF  tt  Jtk-  IC RF  7 ZIL  348INTRODUCTION TORADAR SYSTEMS noise,or111noise.Aboveapproximately 500kHz,thenoise-temperature ratioapproaches a constant value.Atafrequency 0£30MHz,atypicalradarIF,itmightrangefrom1.3to2.0. 
 Components can be quasi-harmonic when caused  by wave motion. In practice, the ship is navigated on notions based on course, heading,  and speed in Earth and sea-fixed coordinate systems. The additional wave-induced  motions can produce uncompensated errors in radar-derived information, which add  to any measurement errors in the course, heading, and speed of the vessel. 
 Burgess et al., “Final report on the Joint Doppler Operational Project (JDOP),” 1976–1978,  NOAA Tech. Memo.  ERL NSSL-86, 1979. 
 334 THE MAGNETRON AND THE PULSER [SEC. 10.3 initscourse around the cathode, with the variations ofr-foscillations need not besatisfied exactly. Electrons once instep with the r-ffield remain inthis state long enough togettotheanode, even iftheir angular velocity isnot exactly correct. 
 IEEE Trtrns.. vol. Af3-5. 
 HIKER CAN BE POSITIONED IN THE SIDELOBES OF THAT ANTENNA  THUS REDUCING THE EFFECTIVENESS OF THE JAMMER ! RULE OF THUMB IS TO ANTICIPATE ENHANCED HITCHHIKER PERFORMANCE WHEN 
 As mentioned in Sec. 5.10,  the resolution of targets in range is degraded by the adaptive threshold process.  The above description of the cell-averaging CFAR assumed that the background from  which the threshold was set was determined by sampling in range. 
 Interfering radio  frequency signals that are intentional, such as those produced by jammers, or uninten - tional, such as those produced by other radars or clutter, may significantly degrade the  ch13.indd   57 12/17/07   2:41:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 CANCE 4HE DETECTION SIGNAL CHARACTERISTICS SUCH AS AMPLITUDE OR SIGNAL 
 Boxer, A. S., S. Hershenov, and E. 
 Although  low power TWTs are capable of octave bandwidths, bandwidths of the order of 10 to 20  percent are more typical at the power levels required for long-range radar applications. The  gain, efficiency, and power levels of TWTs are like those of the klystron; but, in general, their  values are usually slightly less than can be obtained with a klystron of comparable design.  A diagrammatic representation of a traveling-wave tube is shown in Fig. 
 Thusthreeorfourbitsshouldbesufficient for mostlargearrays.exceptwhereverylowsidelobes aredesired. ;\lthough theaboveassumed arandl'1l1 distribution ofphaseerroracrosstheaperture for computation ofthermssidelobe level,theactualphasedistribution withquantized phase shifters islikelytoheperiodic. Theperiodic natureofthequantized phasewillgiveriseto. 
 In industry this has been applied to the measurement of turbine-blade vibration, the  peripheral speed of grinding wheels, and the monitoring of vibrations in the cables of suspen-  sion bridges.  ~ost of the above applications can be satisfied with a simple, solid-state CW source with  powers in the tens of milliwatts. High-power CW radars for the detection of aircraft and other  targets have been developed and have been used in such systems as the Hawk missile systems  (Fig. 
 Noncoherent pulse radar performance is affected by front-end characteristics in three ways. Noise introduced by the front end restricts the maximum range. Front-end saturation on strong signals may limit the minimum range of the system or the ability to handle strong interference. 
 TO 
 2. Signal Model of Inisar Near-Field Imaging The InISAR system includes multiple antennas. This paper proposes a dual-antenna ISAR imaging system. 
 Davis: A Study of Array Beam Switching Techniques. Ro111e  Air l>er-elo11111e11t Center Tl'Clrnical Doc11111e11tary Report No. RADC-TDR-64-421, December, 1964. 
 CONTROLLED PRECISION TWO 
 Radar is used for enhancing the safety of ship travel by warning of potential  collision with other ships, and for detecting navigation buoys, especially in poor visibility.  In terms of numbers, this is one of the larger applications of radar, but in terms of physical  size and cost it is one of the smallest. It has also proven to be one of the most reliable  radar systems. 
 D. Sirmans and B. Urell, “On measuring WSR-88D antenna gain using solar flux,” NWS ROC  Engineering Branch Report, 2001. 
 Inthe case ofASV operating on200 Me/see, similar returns from the seawere experienced, but the returns from ship targets were sostrong that signals were sought and tracked at ranges beyond the seareturn. Aircraft echoes were many times weaker, sothat aircraft could beseen only atranges shorter than the ground return. Itwas clear that thebest hope ofescaping thk limitation was tomake useofasharper beam inAIequipment, and since themaximum antenna size was limited bythe necessity ofaircraft installation, considerable effort was exerted todevelop amicrowave AI. 
 For fewer oscillators, itissomewhat smaller than one-half, and formore than twelve oscillators, somewhat larger. The anode and cathode diameters forany given type arepropofiional to thewavelength and tothe square root ofthe anode voltage. The particular resonant system shown consists ofeight side cavities. 
 InFig. 3,25, the bright line marking theeast shore oftheSusquehanna River is characteristic ofthestrong reflections returned bysharply inclined river embankments. The radar signals received from man-made structures are often too strong tobcfully explained interms ofthesolid angle intercepted bythe targct. 
 Itisperhaps unnecessary toremark that attenuations Wavelength incm F,c. 216.-Attenuation caused bywater vapor (Curve a)andoxygen (Curve b). Curves applies toanatmosphere containing 10goiwater vapor perm3. 
 Further details can be obtained  from SRI International USA. 21.10 LICENSING All countries require that GPR systems are properly regulated and operated in accor - dance with national and international requirements. Users should consult with their  national authorities to determine the regulatory environment. 
  
 g-JG(O,c/J)do. wheredQ=solidanglegivenbysin0dOdc/J.Thebrightness temperature T8(0,4»isoftena complicated function, and1;,mustbeapproximated bynumerical means.Theantenna tempera­ tureisanaveragevalueofthebrightness, orspace,temperature inthefieldoftheantenna pattern. ......'".,'. 
 TI'etrack-/llaillte/lll/lce function determines whennewobservations shouldbemadeon existing tracksinordertoupdatetheentriesinthetrackfile'.Trackmaintenance notonly establishes whenthenextradarobservation mustbemade,buttakesthestepsnecessary to obtainit.Inperforming thisfunction itisoftenconvenient toobtainthetargetposition estimate inradarcoordinates. Radarerrorscanbereadilyhandled inthiscoordinate system.If thetargetisanaircraft, itsposition can.then be converted intocartesian coordinates for smoothing andextrapolation ofitstrajectory. Aconstant~velocity targetflyingastraight line, nonradial coursewouldhaveradialacceleration inthespherical coordinates oftheradar, whichisav~ided withcartesian coordinates. 
 The ability of the operator to detect radar signals in the presence of noise or clutter  cannot be determined with as great a reliability as can the performance of the electronic  threshold detector described in Chap. 2. Human behavior is certainly less predictable than  that of an electronic device. 
 131–137, January 1981. 65. K. 
 Tracking radars are used to com - pute the impact point of a launched missile continuously during the launch phase in case  of missile failure for range safety. If the impact point approaches a populated or other  critical area, the missile is destroyed. Missile-range instrumentation radars are normally  used with a beacon (pulse repeater) to provide a point-source echo—usually its pulse  is delayed to separate it from the target echo—and with high signal-to-noise ratio, to  achieve precision tracking on the order of 0.05 mil in angle and 5 m in range. 
 TER AND JAMMING (IGH RESOLUTION DOPPLER FILTERING IS PERFORMED IN A CONVENTIONAL &&4     PERHAPS WITH $0#! CLUTTER CANCELLATION $OPPLER FILTER OUTPUTS ARE USED  TO FORM MAIN 
 Thus e-l/2(Vx/aapm)2 = Q 25 or apm = 0.6^: (16.5) where Vx and a are in consistent units. This value is lower than ones derived by other authors.4'5 However, it agrees with more exact analysis of antenna radia- tion patterns and experimental data analyzed by the author. A more exact value of the parameter apm may be obtained by matching a two- . 
 CHASING CONCEPT USES A SINGLE  BEAM AND 230 THAT RAPIDLY SCANS THE VOLUME COVERED BY THE TRANSMIT BEAM  CHASING THE PULSE AS IT PROPAGATES FROM THE TRANSMITTER 4HE RECEIVE BEAM 
 60. A. Farina and R. 
 Peripheral effects and environmental influences, as well as sensitivity, will be dealt with later.    On the sender -side of the Radar a power PT will be radiated.  With a range R from the transmitte r  a power density at the target St results from isotropic (spherical) radiation   € St=PT 4πR2 (3.1)  This is the power density of an omni -directional antenna with a range R. 
 CM RADAR ATTENUATION OF THE 7ICHITA  &ALLS STORM BY INTERVENING PRECIPITATION v IN  TH #ONF 2ADAR -ETEOROL  !-3  "OSTON      PP n  0 * %CCLES AND $ !TLAS  h! DUAL 
 ÊÊ -- 
 Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 12.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 Scan aberrations lead to moderately higher scan losses and slight beam scan angle  deviations from those predicted by Eqs. 12.29 and 12.30 when ideal ESA plane wave  excitations, i.e., linear phase slope, are applied. 
 However,  clutter that enters the radar receiver via the antenna sidelobes has doppler frequencies that  cannot be rejected by conventional filtering, since targets of interest can have the same doppler  as the side lobe clutter. An adaptive array antenna can place nulls in the direction of sidelobe  clutter by using the side lobe clutter itself as the signal to be cancelled. This is accomplished by  separating the sidelobe clutter from the main-beam clutter by doppler filtering. 
 Thus a canceler will, in theory, fully reject signals with an ideal spectrum, as shown here. In practice, however, the spectral lines in clutter signals are broadened by motion of the clutter (such as windblown trees) and by motion of the antenna in a scanning radar. Barlow1 stated that the returns from clutter have a gaussian spectrum, which may be characterized by its standard deviation av. 
   COLOR GLASSES 4O UNDERSTAND THE THEORY OF )N3!2  WE FIRST CONSIDER TWO ANTENNAS   ! AND "  SEPARATED  VERTICALLY BY A BASELINE  ,  OBSERVING A POINT TARGET  A THAT IS ON A FLAT GROUND AT RANGE  2  THE RADAR LINE 
 PLEX &)2 FILTER  WHERE THE COEFFICIENTS ARE THE COMPLEX CONJUGATE OF THE TRANSMITTED BASEBAND WAVEFORM SAMPLES IN TIME 
 SCATTER  TIME 
 Noise from automobile ignition, electric razors, power tools, and  nuorescent lights are examples. It is of little concern at UHF or higher frequencies.55  Solar noise. The sun is a strong emitter of electromagnetic radiation, the intensity of which  varies with time. 
 Zoughi, L. K. Wu, and R. 
 However, the detection of a small target, such as  ch22.indd   6 12/17/07   3:02:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 
 -   * 2 +LAUDER  ! # 0RICE  3 $ARLINGTON  AND 7 * !LBERSHEIM  h4HE THEORY AND DESIGN OF CHIRP  RADARS v "ELL 3YST 4ECH *  VOL   PP n  *ULY    # % #OOK AND - "ERNFIELD   2ADAR SIGNALS !N )NTRODUCTION TO 4HEORY AND !PPLICATION    .EW 9ORK !CADEMIC 0RESS     # % #OOK AND * 0AOLILLO  h! PULSE COMPRESSION PREDISTORTION FUNCTION FOR EFFICIENT SIDELOBE  REDUCTION IN A HIGH 
  
 Similar processing is done in the ∆AZ and ∆EL channels with exceptions, as shown in  Figure 4.8. For those range-doppler cells with declared detections, the imaginary part  of the ∆AZ/Σ and ∆EL/Σ ratios are used for phase comparison monopulse to estimate the  azimuth and elevation angles, respectively, relative to the center of the Σ main beam.  The angle estimates are computed for each coherent look and then averaged over the  number of CPIs noncoherently integrated via PDI. 
 F. Adams, R. J. 
 POLARIZATION LOBES GENERATED BY THE REFLECTOR SURFACE  4HIS OCCURS  BECAUSE THE ANGLE 
 For phased array systems with modest  power levels, the solid-state solution offers advantages that make it attractive as the  basis for a radar transmitter. The general replacement of high-power microwave tubes by solid-state devices has  not been straightforward. Attempts to replace existing tube-type transmitters with a solid- state retrofit have been hindered by the requirement to be a form, fit, functional replace - ment for the incumbent hardware. 
 498 THE RECEIVING SYSTEA{—IA’DICA TORS [SEC. 137 Grid glnow rises, until att,itreaches cutoff and regeneration occurs in the reverse direction, and soon. Thus two square waves ofopposite phase are available from the two plates. 
 OUT SIDELOBES  BUT AT A COST OF RELATIVELY HIGH NEAR 
 R., and E. J. Dutton:" Radio Meteorology," National Bureau of Standards Monograph 92,  Mar. 
 The broad central part of these patterns is due to a triple-bounce mechanism  between the three participating faces, while the “ears” at the sides of the patterns  are due to the single-bounce, flat-plate scattering from the individual faces. Along  the axis of symmetry of the trihedral reflector in Figure 14.9 ( q = 0°, f = 0°), the  RCS is pL4/3l2, where L is the length of one of the edges of the aperture. Not  shown are the echo reductions obtained when the trihedral faces are not perpen - dicular to each other. 
 Ninth Int. Symp. Remote Sensing Environ. 
 MATCHING COMPONENTS TO ACHIEVE AN ACCEPTABLE LEVEL OF IMPEDANCE PREMATCHING 4HE MICROWAVE POWER 3I "*4 IS INVARIABLY AN .0. STRUCTURE &IGURE  E  WITH  A VERTICAL DIFFUSION PROFILE IE  THE COLLECTOR CONTACT FORMS THE BOTTOM LAYER OF THE CHIP 4HE 0 
 -1'lic above applies for a square-law detector. Trunks5 has shown that the collapsing loss  for a linear detector differs from that of the square-law detector, and it can be much greater.  .The corliparison between the two is shown in Fig. 
 The magnetron power oscillator was at one time very popular, but it is seldom used  except for civil marine radar (Chapter 22). Because of the magnetron’s relatively  low average power (one or two kilowatts) and poor stability, other power sources  are usually more appropriate for applications requiring long-range detection of small  moving targets in the presence of large clutter echoes. The magnetron power oscil - lator is an example of what is called a crossed-field tube . 
 PROCESSING THROUGHPUT REQUIREMENTS 7ITH DIFFER 
   2!$!2 #  )/.#!0  AND !-"#/- n ,UCAS  PROVIDES DETAILS OF THESE MODELS AND THEIR  ORIGINS 3OME OF THE PREDICTION METHODS HAVE NOT BEEN WELL DOCUMENTED ALTHOUGH WIDELY DISTRIBUTED ALSO  USERS FREQUENTLY hIMPROVEv UPON A MODEL AND PREDICTION METHOD TO SUIT THEIR SPECIFIC NEEDS !S AN EXAMPLE  THE MODEL 2!$!2 #  IS THE BASIC  BUILDING BLOCK OF 4HOMASON ET AL IN .2, 2EPORT  HOWEVER  THEY ADDED A $  REGION  A COLLISION 
 Barton, Modern Radar System Analysis , Norwood, MA: Artech House, 2005, pp. 228–230. 18. 
 McGraw-Hili BookCompany, NewYork,1970. 6.IEEETestProcedures forAntennas, IEEETrails..vol.AP-I3.pp.437-466, May,1965. 7.Fry.D.W.,andF.K.Goward: "Aerials forCentimetre Wavelengths," Cambridge University Press. 
 Tang, S.; Zhang, L.; Guo, P .; Liu, G.; Zhang, Y.; Li, Q.; Gu, Y.; Lin, C. Processing of Monostatic SAR Data with General Conﬁgurations. IEEE T rans. 
 TRACKING CHANNEL 3EVERE ELEVATION ERRORS MAY CAUSE SOME CROSS COUPLING OF THE ERROR TO THE AZIMUTH CHANNEL 2OUGH SURFACES CAUSE DIFFUSE SCATTERING  WHICH CAN CONTRIBUTE ERRORS TO BOTH AZIMUTH AND ELEVATION TRACKING   $IFFERENT PATH GEOMETRIES SUCH AS NON 
 DAY  FOR A PARTICULAR MONTH AND LEVEL OF SOLAR ACTIVITY     
 LEVEL RISE  WHICH IS A KEY CLIMATE 
 Apr. 3, 1975. Available from National Technical Information Service. 
 By using three essentially duplicate sources and measuring the phase noise generated by each pair at all the desired offset frequencies, one derives three sets of measurements. This leads to three equations with three un- knowns, and the phase noise of each of the three sources can be derived as a function of frequency. If one of the internal sources supplied by the instrumen- tation is used, there is a distinct limitation owing to the phase-noise characteristic of that particular internal source. 
 I86  Uncertainty relation. 408-409  l lneqilally spaced arrays, 33 1 -332  Ilnfocused SAR, 518 -519  l lriiforr~i prohahility density function.  Il~~ipr it!. 
 R. J. Mailloux, Chapter 21 in Antenna Engineering Handbook , R. 
 34!4% 42!.3-)44%23   ££°Îx   6 'REGERS 
 Screens incorporating the green willemite phosphor used inordi-. 480 THERECEIVING SYSTEM—INDICATORS [SEC. 13.2 nary oscilloscope tubes and known astype P-1 (phosphor number 1)arealmost universally used insuch applications. 
 Then the difference pattern ∆(q ) is  synthesized independently, based on the relationship required at design radar platform  FIGURE 3.11  Phasor diagram showing the return from a point scatterer due to platform  motion ch03.indd   11 12/15/07   6:02:58 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 
 Ground­ based radars were av;,iilable for air search and height finding so as to perform ground control  of intercept (GCI). Coastal, shipboard, and airborne radar were also employed successfully in  significant numbers. An excellent description of the electronic battle in World War 11 between  the Germans and the Allies, with many lessons to offer, is the book" lnstrumettts of Darkness"  by Price.13  The French efforts in radar, although they got an early start, were not as energetically  supported as in Britain or the United States, and were severely disrupted by the German  occupation in 1940.12 The development of radar in Italy also started early, but was slow. 
 The technique was initially called simulta- neous lobing, which was descriptive of the original designs. Later the term monopulse was used, referring to the ability to obtain complete angle error infor- mation on a single pulse. It has become the commonly used name for this track- ing technique. 
 SENSITIVE AND LEADS TO MORE SEVERE BANDWIDTH RESTRICTIONS THAN MOST OTHER FEEDS 4YPE  B IS CENTER 
 to the radar. Thus the various mathematical  models cannot, in general, be expected to yield precise predictions of system performance.  It has been suggested38•39 that if only one parameter is to be used to describe a complex  target, it should be the median value or the cross section with Rayleigh statistics (Swerling  cases 1 and 2). 
  
 The solid-state transmitter consists of up to 40 modules generating 132 kW of total RF power at the peak of a 150-JJLS pulse and up to 5 kW of average power. The height accuracy claimed for the radar by its manufacturer is 1700 ft on a small fighter at 100 nmi.14 A radar which is a hybrid mix of stacked beams and phase steering is the RAT-31S, an S-band radar which phase-steers a stack of four beams in elevation to cover the surveillance volume. The radar employs monopulse to determine tar- get height. 
 The comparison is made at  each range bin for each pulse received and processed by the two parallel channels.  Thus, the SLB decides whether or not to blank the main channel on a single-sweep  basis and for each range bin. A target A in the main beam will result in a large signal  in the main receiving channel and a small signal in the auxiliary receiving channel. 
 Equation 14.16 may also be used to estimate the RCS of a truncated right  circular cone if the radius a is replaced by the mean radius of the cone and  is replaced  by the length of the slanted surface. Although the theory of physical optics offers a significant improvement over geo - metric optics for flat and singly curved surfaces, it suffers other drawbacks. Even  though we obtain the proper result for most of the illuminated surface, the physi - cal optics integral yields false contributions from the shadow boundaries, as already  noted. 
 Skolnik (ed.).  McGraw-Hill Book Company, New York, 1970.  59. 
 [CrossRef ] 28. Tropp, J.A.; Gilbert, T.C. Signal recovery from random measurements via orthogonal matching pursuit. 
 R. Schroeder, J. Puls, F. 
 : ,  Dwell (N-1) Owel!N  Figure 8.31 Representative command/response sequence. (Courfe.'i_r RCA. Inc.) Command  dota to,  · dwell (N;. 
 Most of the studies are based on a polarimetric SAR system. Ferro-Famil et al. analyze the responses Sensors 2019 ,19, 346; doi:10.3390/s19020346 www.mdpi.com/journal/sensors 249. 
 Dept. of Commerce. ESSA hlorlogruplt 1, 1966. 
 &REQUENCY !MPLITUDE .OISE  (IGH 
 (14) isthequantity G,k* which isproportional tothe aperture ofthe radar antenna. This leads one tosuspect that long beacon ranges should be,ingeneral, more difficult toachieve atshorter wavelengths. Antenna apertures are rarely increased inarea when shorter wavelengths areemployed: onthe other hand, available r-fpower generally decreases markedly with decreasing wavelength. 
 BOUND PROPAGATION PATH TO A TARGET IS ALMOST IDENTICAL TO THE IN 
 Accordingly, the detected pulsar signals reﬂected by a moving space object can be considered as a delayed copy of such pulses and modelled within a passive inverse SAR scenario. A range compression approach for this speciﬁc ISAR imaging was introduced theoretically and demonstrated through numerical simulations. The Crab Nebula pulsar was considered as emission source. 
 LOADING OR DISTRIBUTED 
  +1 
 It is thus possible to determine when the  target is in the low-angle region by sensing large elevation-angle errors and locking the  antenna in elevation at some small positive angle while continuing closed-loop azimuth  tracking.43 This is sometimes called ofjlaxis tra~king,~' or of-boresight tracking..'7 The eleva-  tion angle at which the antenna is fixed depends on the terrain and the antenna pattern.  Typically it might be about 0.7 to 0.8 beamwidth. With the beam fixed at a positive elevation  angle, the elevation-angle error may then be determined open-loop from the error-signal  voltage or the elevation measurement may simply be assumed~~t~lfway between  the horizon and the antenna boresight. 
 lleanf~-bile battleexperience inilfrica shom-ed that anindependent radar setcould pass toairborne fighters useful information onthe disposition ofenemy aircraft. The American officer’s novel idea didnot gain immediate acceptance since control ofseveral squadrons offighters indaylight requires tech- niques quite different from those ofthe GCI control ofasingle night- fighter. Finally, the officer ~f-as giiren permission bythe late .Iir C7hief IIarshal SirTrafford Leigh-lIallory tocontrol wings offighters directly from his radar station, entirely independently ofthe sector-control system. 
 The greater the transmitter frequency deviation in a given time interval, the more accurate the  measurement of the transit time and the greater will be the transmitted spectrum. 82 INTRODUCTION TO RADAR SYSTEMS  Range and doppler measurement. In the frequency-modulated CW radar (abbreviated  FM-CW), the transmitter frequency is changed as a function of time in a known manner. 
 Target suppression occurs at all interfaces (e.g., land, sea) where the homogeneity assumption is violated. However, some tests exist, such as the Spearman Rho and Kendall Tau tests,33 that depend only on the test cell. These tests use the fact that as the antenna beam sweeps by a point target, the signal return increases and then decreases. 
 A feed  horn is rotated within this circle, transferring power from the transmitter to each reed or group  of feeds in turn. The rotary horn may be flared to illuminate more than one elementary feed of  the row of feeds. All the transmission lines in the organ-pipe scanner must be of equal length. 
  ASYMPTOTE  0HILLIPS DERIVED THIS ASYMPTOTIC BEHAVIOR ON DIMENSIONAL GROUNDS  AND A WIDELY USED  SIMPLIFICATION  OBTAINED BY REPLACING THE SMOOTH PEAK IN &IGURE  BY A SHARP CUTOFF  IS GENERALLY REFERRED TO AS THE 0HILLIPS 3PECTRUM   7+    + 
 TRACKING REQUIREMENTS  "ORESIGHT IS THE ELECTRICAL  AXIS OF THE ANTENNA OR THE ANGULAR LOCATION OF A SIGNAL SOURCE WITHIN THE ANTENNA BEAM AT WHICH THE ANGLE 
 R. D. Ray, “Applications of high-resolution ocean topography to ocean tides,” in Report of the  High-Resolution Ocean Topography Science Working Group Meeting , D. 
 Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation.  THE PROPAGATION FACTOR, FP, IN THE RADAR EQUATION  26.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 Superrefraction.  If the troposphere’s temperature increases with height (tem - perature inversion) and/or the water vapor content decreases rapidly with height, the  refractivity gradient will decrease from the standard. 
 There are two types of  bandwidth encountered in radar. One is the signal bandwidth , which is the bandwidth  determined by the signal pulse width or by any internal modulation of the signal. The  other is tunable bandwidth . 
 ARRAY WITH RADIATING ELEMENTS ABLE TO SEPARATELY RECEIVE AND POSSIBLY TRANSMIT THE TWO ORTHOGONAL COMPONENTS OF A RADAR WAVE  AND OF A DUPLICATION OF THE RECEIVER AND SIGNAL PROCESSING 3IDELOBE "LANKING 3,"  3YSTEM  4HE PURPOSE OF AN 3," SYSTEM IS TO PREVENT  THE DETECTION OF STRONG TARGETS AND INTERFERENCE PULSES AS THEY MIGHT APPEAR AFTER PULSE COMPRESSION  ENTERING THE RADAR RECEIVER VIA THE ANTENNA SIDELOBES 4HUS  3," IS MAINLY USED TO ELIMINATE INTERFERENCE FROM OTHER PULSE TRANSMISSIONS AND DELIBER 
 This inability to precisely measure the true backscattering cross  section requires that quantitative measurements of precipitation rates be corrected for  attenuation when possible. Second, if the attenuation due to precipitation or the intervening medium is suf - ficiently great, the signal from a precipitation cell behind a region of strong absorp - tion may be totally suppressed. One example of the potentially serious consequences  of very strong absorption is the impact it might have on aviation storm avoidance  radars, most of which are in the 3-cm band. 
 T. Ransone, Jr., and J.C. Daley: Variation of the NRCS of the Sea with Increasing  Roughness, J. 
 S. Symons, “Tubes: Still vital after all theses years,” IEEE Spectrum , vol. 35, pp. 
 The incremental change inoutput voltage produced byone step ofresistance determines the limit ofsensitivity ofthe regu- lator. Anairdashpot isusually provided todamp any oscillation or hunting ofthearmature. Regulating Anti.hunt r.,hfi. 
 Here, it is noted a basic difference between surveillance and  tracking radar: the detection range of a tracking radar improves as the frequency is  increased for a fixed-size antenna. The reason for this improvement is that the antenna  gain is directly increased with frequency, thereby focusing more power on the target.  This increased power is integrated for a time, which is inversely proportional to the  bandwidth of the servo control loop. 
 Substituting inloEq.(14.22)G,=G,=G=Tt2/O"Or'where0"=azimuth beamwidth; andT.:=tsO,,/OT' ts= revisittime(scantime)and0T=totalazimuth anglecoverage, weget (" R4 ~PavA2(JFpts -64NoO"O;(SjN)LsO r Lumping intoasingleconstant Ktheconstants inthisequation andtheparameters assumed tobegiven(including 0,.)ornotunderthecontroloftheradardesigner. weget R4=K!,av 0" Thusameasure oftheperformance ofanHFsurveillance radaristheratiooftheaverage powerdivided bytheazimuth beamwidth. Whencomparing theperformance oftworadars withdifferent antenna heightsaswellasdifferent widths,ameasure ofrelativeperformance is Measure ofperformance =Pa,·wh2(14.26) where IV=anlenna widthandIt=antenna height.Ifseparate antennas areusedfortransmit andreceive, IVisthewidthofthereceiving antenna and1t2isreplaced byh,It,where It,=transmitting antenna heightandIt,=receiving antenna height.. 
 ch13.indd   71 12/17/07   2:41:17 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 Although time-base generators for television sets  are relatively complicated—and, indeed, two time-bases  are needed, as the tube is scanned horizontally 405 times  while traversing the tube screen twice in a vertical  direction—they are not suitable for the majority of radar  systems, as the degree of linearity may not be sufficient.  Tt will readily be seen that if we do need a radar display  where our electronic clock demands a linear time-base,  then there must not be the slightest variation in the  potential’s straight-line characteristic, or we shall have the same trouble in getting correct timing (and therefore  correct reading of distance) from our radar clock as we should from an ordinary clock the hands of which did  . ?  RADAR TIME-~BASES 73  not maintain an exactly constant speed in travelling  from midnight to midday. 
 ~Microwave Transmission Circuits, Vul.9.. SEC. 11.2] COAXIAL LINES 395 lines have been almost completely supplanted bystub-supported lines inthe 10-cm region. 
 Each mixer is supplied with a different LO frequency. The transmitting antenna  provides a single beam illuminating the coverage of the N receiving beams. As described in  Sec. 
 IDEAL !$ CONVERSION !PPLICATIONS 4HE CONVENTIONAL APPROACH OF USING A PAIR OF CONVERTERS TO DIGI 
 What is significant is whether the time changes between pulses. The time change, which is of the order of a few nanoseconds for an aircraft target, is determined by comparing the phase of the received signal with the phase of a reference oscillator in the radar. If the target moves between pulses, the phase of the received pulses changes. 
 14. Lobanov, M. M.: "Iz Proshlovo Radiolokatzii" (Out of the Past of Radar), Military Publisher of the  Ministry of Defense, USSR, Moscow, 1969. 
 Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar.  AN INTRODUCTION AND OVERVIEW OF RADAR  1.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 ● Description of the need or problem to be solved .  This is from the viewpoint of the customer or the user of the radar. 
 Without anappro- priate introduction, however, such atreatment might behopelessly confusing. Accordingly, there follows acatalogue ofexisting indicator IByL.N.Ridenour. 160. 
 M. Caspers, “Bistatic and multistatic radar,” Chapter 36 in Radar Handbook , M. I. 
 &- PERIOD 4O MITIGATE THIS PROBLEM  A THREE 
 TO 
 )(.,)&)&. #!  (.!((  $#( & )/-!%!!*$(# ("),' .$)()/-!%!!*$(# ("),' .$)(  (.!(( .   ")34!4)# 2!$!2   ÓÎ°££ (ITCHHIKERS USING COOPERATIVE MONOSTATIC RADAR TRANSMITTERS ALSO HAVE THE INHER 
 Since the cross section of objects  within the Rayleigh region varies as A-4, rain and clouds are essentially invisible to radars  which operate at relatively long wavelengths (low frequencies). The usual radar targets are  much larger than raindrops or cloud particles, and lowering the radar frequency to the point  where rain or cloud echoes are negligibly small will not seriously reduce the cross sectior~ of  the larger desired targets. On the other hand, if it were desired to actually observe, rather than  eliminate, raindrop echoes, as in a meteorological or weather-observing radar, the higher  radar frequencies would be preferred. 
 TED WITH A CONSTANT 02) 4HE NEXT #0) USES A DIFFERENT 02) #ONSTANT DUTY CYCLE CAN BE MAINTAINED BY CHANGING THE TRANSMITTED PULSE LENGTH IN PROPORTION TO THE CHANGE IN THE 02) )F PULSE COMPRESSION IS USED  THE RANGE RESOLUTION OF THE COMPRESSED PULSE CAN BE MAINTAINED BY CHANGING THE PULSE COMPRESSION WAVEFORM )F IT IS NECESSARY TO UTILIZE PRECISELY THE SAME WAVEFORM AND 2& PULSE LENGTH FROM #0) TO #0)  WITH  FOR EXAMPLE  A KLYSTRON TRANSMITTER  THE BEAM PULSE OF THE KLYSTRON CAN BE VARIED TO MAINTAIN CON 
 For ease of reference, the conventional signal processing stages responsible  for transforming the receiver outputs into standard radar products are discussed in  Section 20.11, together with more specialized techniques. Antennas.  From the reception viewpoint, it is desirable to have fine azimuthal  resolution for several reasons, including (i) to improve target location accuracy and  tracking performance, (ii) for detailed clutter mapping, and (iii) to reduce the clutter  amplitude levels to values permitted by system dynamic range and slow-target detec - tion requirements. 
 In practice, these can be esti - mated and then corrected if the altimeter measures round-trip range at two different  frequencies. The delays imposed by the atmosphere are comprised of two components:  the dry atmosphere and water-vapor. The dry atmosphere component is well-known  and stable at long spatial scales; in practice, the resulting delay is compensated by  recourse to model predictions. 
 Hall and W. W. Shrader32 © IEEE 2007 and  H. 
 Thusradarsatthelowerfrequencies whicharemoreresponsive tothelongergravitywaves mightexperience avalueofrrothatdoesnotseemresponsive totheimmediate valueofwind speed.Another complicating factoristilebreaking ofwavesandthegeneration ofspray,foam, orwhitecaps whichhaveaneffectontheradarbackscatter. Thepresence ofswellwaves alongwiththewind-driven seacanalsoaffecttheradarbackscatter. Stillanother important factorwhenattempting tounderstand theeffectofthewindonseaclutteris·thedifficulty inaccuratel~ estimating windspeedatsea.6. 
 The dipole is always used  over a renecting ground plane, or its equivalent, in order to confine the main beam.radiation to  the forward direction.  Slots cut into the walls of a waveguide are similar in many respects to the dipole since the  slot is the Babinet equivalent of the dipole. A slot array is generally easier to construct at the  higher microwave frequencies than an array of dipoles. 
 5. Radar scheduling and control. The result of the automatic tracking process is a track file that contains a track state  for each target detected by the radar. 
 F, pp. 630–637, December 1986. 64. 
 TRACKING RADAR 187  10. Field. J. 
 3HALOM  7 $ "LAIR  AND ' ! 7ATSON  h)--0$!& FOR RADAR MANAGEMENT  AND TRACKING BENCHMARK WITH %#- v )%%% 4RANS  VOL !%3n  NO  PPn    ( "LOM AND 9  "AR 
 Zrnic, “Systematic phase codes for resolving range overlaid signals  in a doppler weather radar,” J. Atmos. Oceanic Technol.,  vol. 
 Thefalse-alarm probability mayalsobedefinedastheratioof theduration oftimetheenvelope isactually abovethethreshold tothetotaltimeitcOllldhave beenabovethethreshold, or (2.25). Time -  Figure 2.4 Envelope of receiver output illustrating false alarms due to noise.  where t, and & are defined in Fig. 
 MOVING PARTS EG  HELICOP 
 VIDE FINE CONTROL OF THE ELEVATION PATTERN WITH A SINGLE ELEVATION COLUMN FEED ARRAY AND SO IS VERY COST EFFECTIVE 4HE ELEVA 
 Then, upon reflection from the subreflector, the feed energy  converges at the common focus and diverges again as a spherical wave before finally  reflecting from the main reflector. The confocal system has several interesting properties, tied to the magnification  factor M:  M = fM / fS (12.28) where fM and fS are the focal lengths of main and subreflectors, respectively. The first  property shows that the system is essentially a feed source magnifier. 
 VA was the USA AN/APS-2, a high-power version of ASV Mk. V, discussed in chapter 8). The discriminator circuit used on ASV Mk. 
 Like  astronomy, radar is a subject which can be studied  purely from the aspects of mathematics, although most  ‘of us find it more entertaining to ponder on the mech-  ~ anics of the subject than on the complex arithmetic.  You can work out for yourself several typical examples  of radio-wave speed and object distance. You will find,  for example, that 186 miles represents a time-interval  of 2 milliseconds, 9-3 miles an interval of 100 micro-  seconds, 1 mile 10-7 microseconds, and 7s mile 1-07  microseconds. 
 It also  reduces the likelihood of mutual interference between equipments, and makes more difficult  Frequency.- GHz  30 300 3000 3 X 104  , ... Millime1er -+-Submillimeler--+f+---Far infrared·+  60 GHz 02  resonance  Ka i 94 GHz band window It t  1.0 cm 10 mm 01 mm  Wavelength 10J-Lm 3 X 105  ··Infrared· ~1 , ..  Visible  1 OJ-Lm  Figure 14.14 The electromagnetic spectrum of frequencies above the microwave region. 
 The sensitivity presented there is normalized by the sensitivity of the uniform-sum, linear-odd delta case, and is plotted for various values of the two parameters used to specify Taylor and Bayliss weighting, «, and sidelobe ratio (SLR). It should be noted that not all combinations of n and SLR depicted in the figure constitute good aperture illu- mination design choices. It is sometimes convenient and/or economical to perform coherent signal pro- cessing at RF or IF, by analog techniques, and then to carry out envelope and phase detection in the two channels. 
 LOWING TEST CAN BE ADOPTED ,ET  . BE THE NUMBER OF MEASUREMENTS EXCEEDING THE DETEC 
 The concept of the cx.-P tracker or the Kalman filter also can . 186 INTRODUCTION TO RADAR SYSTEMS  be applied to a continuous, single-target tracking radar when the error signal is processed  digitally rather than analog. Indeed, the equations describing the a-P tracker are equivalent to  the type II servo system widely used to model the continuous tracker.)  If, for some reason, the track-while-scan radar does not receive target information on a  particular scan, the smoothing and prediction operation can be continued by properly  accounting for the missed data.80 However, when data to update a track. 
 The appropriate  correction factors are applied to bring the antenna into calibration for a given mode of  radar operation. Once the active phased array is fielded, in- the-field calibration must be performed to keep  the antenna within specifications. Active com - ponents drift over time and these aging effects  require calibration to be performed in the field. 
 beacon is sharply beamed by  directional aerial arrays.  Of the various ground beaceass in SCS-51 the ‘local-  . TRAVEL BY BEACON 161  izer’ assists the aircraft to get in line with the runway,  from a distant point, and guides it in to the centre of  the runway. 
 Poterttial for large peak andlor average power. If necessary, each element of the array can be fed  by a separate high-power transmitter with the combining of the outputs made in "space "  to obtain a total power greater than can be obtained from a single transmitter.  Control of the radiation pattern. 
 AD9858 1-GSPS direct digital synthesizer data sheet, Rev. A, 2003, Analog Devices, Norwood,  MA (available at www.analog.com). 48. 
 2. Ash, J.; Emre, E.; Lee, P .; Edmund, Z. Wide-Angle Synthetic Aperture Radar Imaging: Models and algorithms for anisotropic scattering. 
 Antennas Propag. 1981 ,29, 740–748. [ CrossRef ] 13. 
 ALTITUDE SEGMENT OF EACH ORBIT  THE SPACECRAFT WAS ORIENTED TO POINT THE ANTENNA TOWARD %ARTH 4HE ANTENNA HAD TWO FEEDS  ONE AT 3 BAND (( 
 8 ! 4ERRA3!2 
 1 17 1 - 1 183, September, 1966.  61. Becker, J. 
 Kellog, “Digital processing rescues hardware phase errors,” Microwaves & RF , pp. 63–67,  80, November 1982. 66. 
 The difference signal is used to compensate for the effects  of platform motion. If the system is designed to transmit the sum pattern Σ(q ) and receive both Σ(q ) and  a difference pattern ∆(q ), then at the design speed the received signal Σ(q )∆(q ) can be  applied as the correction signal. The actual correction signal used to approximate Ec is  k Σ(q )∆(q ), where k is the ratio of the amplification in the sum and difference channels  of the receiver. 
 P. E. Howland, “FM-radio based bistatic radar,” presented at AOC 4th Multinational PCR  Conference, Syracuse, NY , October 6, 2005. 
 The choice of transmission medium is generally a function of  many parameters, including peak and average power-handling capability, operat - ing frequency and bandwidth, mechanical packaging constraints, and, of course, the  overall loss that can be tolerated. More often than not, a combiner design utilizes a  hierarchy of cascaded designs to sum the outputs of many modules; however, unique  configurations that sum many ports to a single port have been built. Amplitude and Phase Sensitivities . 
 There  may be not one but a large number of echoes. Some,  even remote ones, may be PE’s; some will be moving  in towards the end of the trace; others will be moving  out. If we have set the tube up accurately according to  . 
 28-31, 1974, IEEE Catalog no. 74 CHO 934-0 NEREM.  S 1. 
 Meaningful results have only been achieved over a narrow range of in-plane data   (f = 180°). ● Values of sB0 for f > ∼ 140° are not appreciably different (within ∼ 5 dB) from the  monostatic case. ● Values of sB0 in a broad angular region centered on f = 90° are significantly lower  than elsewhere and typically 10 to 20 dB below the monostatic value; conse - quently, bistatic radar surveillance can be enhanced and hot clutter can be reduced  in these regions. 
 The designated target is tracked in range and  angle to provide a more accurate distance and angle to the target. The tracking  may be open or closed loop. The estimates are then provided to the weapon before  and after launch. 
 POLARIZED AND THE CROSS 
 Appl. Meteorol. , vol. 
 It was known by Sir Rober  Watson-Watt’s workers as early as 1935 that suct  reflections from the ground could be displayed, perhap:  even in map form, but the lack of a high-definition trans.  mitting system prevented anything being done whicl  would at that time have been of operational value. Bu  immediately centimetric radar could be airborne ;  great future opened up for systems such as H2S, becauss  the requisite narrower beams and sharper pulses coulc  be produced on the centimetre wavelengths. 
 22.18 Transmit/Receive M odules  .................................  22.23  On-Board Processors  ........................................  22.24  Prime Power  ...................................................... 
 Inmany cases imperfections inthe transformer are overcome bytaking the feedback from itssecondary circuit. The low deflection sensitivity ofthesweep coils renders itimpractical. SEC. 
 ARRAY LEVEL  TO ACHIEVE AN OVERALL TAPER FUNCTION MORE SIMILAR TO THE "AYLISS ONE THIS IS OBTAINED BY DECREASING THE CONTRIBUTION OF THE CENTRAL SUB 
 Shaping of the surface along the vertical axis is used to spoil  the beam shape in this plane, but because only the phase of the wave across the aperture  is changed, there is less control over the beam shape than in the parabolic and/or phase  cylinder shown in Figure 12.15 b wherein the linear array may be adjusted in amplitude. Very often the radar designer needs multiple beams to provide increased coverage  or to determine angle. Figure 12.15 d shows how multiple discrete feed locations pro - duce a set of secondary beams at distinct angles. 
 TO 
 Actually, the signal received from agiven region, being the vector sum ofthe ~vaves reflected from the indi~-idual drops, fluctuates continually inamplitudp asthese clrops. shift inposition relative toone :mother. ~This fluctuation obeys asimple statistical law, which, forour purpose here, can bestated asfollows: the probability yofrecei~ing, at P arly time, anecho ofintensity (power) Porgreater isjust e~D,where P,isthe a~erage intensity o~-er atime long compared tothe fluctuation time. 
 Moreover, high-pass filtersTRANSMITTER OSCILLATORBALANCED MODULATOR FILTER FILTERS SUM FILTERS DIFFERENCE . having steep slopes to reject clutter are somewhat easier to design near dc than they are at low IF. A disadvantage is the requirement to maintain balanced operation over the full range of doppler frequencies in the two second mixers and in the two 45° phase shifters in order to eliminate false targets. 
 Components Design.—The general system parameters chosen asaresult ofconsiderations outlined inthelast fewsections areasfollows: Wavelength. 10.15 toll.10cm Pulse length, lpsec PltF. .,.,,,..,...............................4oopps Azimuth scan rate,.,.,.. 
 electronically controlled phase shift by variation of the helix voltage.50 The  phase shirt is large enough to allow several taps on a single tube to control the phase of several  nntenna clements simultaneously. 51 Gaseous discharge, or plasma, phase shifters are based on  the variation of the dielectric constant of the gaseous medium as a function of the number of  free electrons, which depends on the current through the device.51 53 Although they can  handle about I kW of power and can be adapted to a wide range of frequencies, it is difficult to  obtain stable operating characteristics with long life in sealed-off tubes. The switching proper­ ties of a ferrite circulator can also be used for constructing a digitally switched, nonreciprocal  phase shifter. 
 ING TECHNIQUES THAT VASTLY IMPROVE DATA QUALITY OVER THE SIMPLE PULSE PAIR PROCESSING ALGORITHM &URTHERMORE  PROCESSORS THAT ADAPT THEMSELVES TO A VARIABLE ENVIRONMENT IN WHICH THEY USUALLY OPERATE ARE FEASIBLE &LEXIBLE PROGRAMMING OF DIGITAL SIGNAL PROCES 
 The discussion here treats pulse systems, but since all other range-measuring systems can be reduced to equivalent pulse systems most results are general. Figure 12.14 shows the way in which pulse measurement of range is used. Fig- ure 12.14« shows a circular pencil beam. 
 CLUTTER POWER AT THE INPUT  4HE SIGNAL IS ASSUMED TO BE AT THE CENTER OF THE DOPPLER FILTE R  )NCORPORATING THE EFFECT OF FILTER WEIGHTING  THE IMPROVEMENT FACTOR FOR A DOPPLER FILTER IS GIVEN BY    )+! !! N M 4N N. NM C  EXP   § ©¨¶ ¸· 
 Hsiao, J. K.: Analysis of a Dual Frequency Moving Target Indication System, Tlie Radio urrd Elrc-  tronic Engineer, vol. 45, pp. 
 316 9.24 Structural Design ofRadomes 316 9.25 Examples ofRadomes 317 GrrAF. 10. THE MAGNETRON AND THE I’ULSER 320 THE MAGNETRON ......... 
 The 3-d B directional coupler is a four-port junction which has the  property that a signal fed into one port will divide equally (in power) between the other two  ports and no power will appear in the fourth port. A 90° phase difference is introduced  hetween the two equally divided signals. Similarly, a signal introduced into the fourth port will . 
 From an examination of Table 20.1,   it is clear that a skywave radar is not simply a microwave radar scaled up in size by  a factor of ~ 1000, that is, in proportion to the wavelength. Referring to the radar  equation, the R–4 loss term means that, for a representative tenfold increase in detec - tion range of HF over microwave, 40 dB extra range loss accumulates. This cannot  all be recovered by radiating more power and increasing antenna gain, for practical  engineering reasons and cost, apart from constraints imposed by ionospheric propa - gation. 
 14.18 and 14.19. Mitzner expressed his result as the diffracted electric-field components parallel  and perpendicular to the plane of scattering in terms of the components of the inci - dent electric field parallel and perpendicular to the plane of incidence. As such, the  diffraction coefficients may be expressed as three separate pairs representing paral - lel-parallel, perpendicular-perpendicular, and parallel-perpendicular (or perpendicu - lar-parallel) combinations. 
 IntheFraunhofer region,theintegral forelectric fieldintensity intermsofcurrent distrihution acrosstheaperture isgivenbyaFourier transform. Consider therectangular aperture andcoordinate systemshowninFig.7.2.Thewidthoftheaperture inthezdimension isa.andtheangleinthey:planeasmeasured fromtheyaxisis1>.Thefar-field electricfield intensity. assuming a~A.is .all(z)E(!/»=.1aiZA(z)exP j2rr~sin1> dz (7.10) where11(:)=current atdistance z,assumed tobeOowing inxdirection. 
 MITTER PULSE 
 X PREFACE  been limited. Omitted from this second edition is the chapter on Radar Astronomy since  interest in this sub.ject has dccrcascti with tltc i~vi~ilithility of space prolws tlliil cilll explore ttlc  planets at close range. The basic material of the first edition that covers the radar equation,  the detection of signals in noise, the extraction of information, and the propagation of radar  waves has not changed significantly. 
 Using the simple radar equation of Sec. 1.2, the power  C received from tlie clutter is  Figure 13.1 Geometry of radar clutter. (a) Elevation view showing the extent of the surface intercepted by  the radar pulse, (6) plan view showing clutter patch consisting of individual, independent scatterers. 
 10.1 1 does not sum all the range cells as described above, but sums the cells ahead of the  test cell separately from the sum of the cells following the test cell. The threshaid is determined  by whichever of the two sums is the greater. This is done to minir-ize the generation of false  alarms at the leading and trailing edges of abrupt clutter regions.' . 
 The use of AIS as an aid-to-navigation  (AtoN) has been put forward as a possible  replacement for racons, which are described in the next section. In principle, AIS  AtoNs could replace racons, but in practice, it would be a retrograde step as they  cannot be used independently of a position fix system, such as GNSS. However, they  can be usefully employed to indicate the integrity of the actual position of the mark,  which may have dragged or become unattached, and other additional data, such as  sea currents. 
 The next option is to manage the data rate, thereby allowing a longer dwell time on the  target (burnthrough mode) along specific spatial sectors where needed. The ability to  vary the data rate in an optimal manner is one of the principal advantages of phased- array radars.3 Another principle of ECCM design against main-beam noise jamming is to mini - mize the amount of jamming energy accepted by the radar. This is accomplished by  spreading the transmitted frequency range of the radar over as wide a band as pos - sible, thus forcing the jammer into a barrage-jamming mode. 
 All oscillators have a noise spectrum. In addition, cavity oscillators, used  because they are readily tunable, are microphonic, and thus their frequency may vary  at an audio rate. The limitation on the improvement factor due to frequency changes  is the difference in the number of radians that the oscillator runs through between  the time of transmission and the time of reception of consecutive pulses. 
 ALL PERFORMANCE 4YPICALLY  THE PATTERN SHAPING IS ENABLED BY A DOUBLY CURVED REFLECTOR FED FROM A POINT 
 BIASINGv AND HAVE BEEN THE PREFERRED CLASS OF OPERATION FOR THE SILICON BIPOLAR TRANSISTORS USED AT 5(&  , BAND  AND 3 BAND "ECAUSE THIS CLASS OF OPERATION IS INHERENTLY NONLINEAR  AS THE TRANSISTOR MODULATES BETWEEN BEING OFF AND SATURATED THROUGH EACH 2& CYCLE  THE HARMONIC CONTENT IS HIGH  AND APPROPRIATE FILTERING OF UNDESIRE D HIGHER ORDER SPEC 
 Some advantage can be gained by including the capability to examine the jammer  signals, find holes in their transmitted spectra, and select the radar frequency with the  lowest level of jamming. This approach is particularly useful against pulsed ECM,  spot noise, and nonuniform barrage noise; its effectiveness depends primarily on the  extent of the radar agile bandwidth and the acquisition speed and frequency tracking of  an “intelligent” jammer. A technique suited to this purpose is referred to as automatic  frequency selection  (AFS).133,138 Another method to reduce the effect of main-beam noise jamming is to increase the  transmitter frequency (as an alternative means to the use of a larger antenna) in order  to narrow the antenna’s beamwidth. 
 NOISE  TEST IN RAIN CLUTTER 5NGATED CONTACTS GENERALLY REPRESENT CLUTTER 'ATED CON 
 Image quality is  typically measured using several image-quality metrics  (IQMs) described in the fol - lowing sections. More detailed discussion of SAR imagery is given by Henderson and  Lewis30 and Oliver and Quegan.31 Point-Spread Function (PSF).  A point target may be considered an impulse input  to a SAR processor, and the PSF in the image may be regarded as an impulse response  (IPR). 
 Technologies and Construction.  Semiconducting materials used in the fabri - cation of transistors are considered to be those materials that are typically neither  conductors nor insulators. The charge carrying properties of these semiconducting  materials can be modified dramatically through the substitution of minute amounts  of impurity ions or through crystal lattice defects, either of which act to modulate the  flow of electrons. 
 35db Fm.3.S.—Return power from aB-26 aircraft at10-cm wavelength asafunction ofazimuth angle. Inmany positions, the power received changes byasmuch as15db forachange ofonly ~inaspect angle. Toalesser, but still very notice- able, extent thecross section isafunction oftheposition ofthepropeller, sothat modulation ofthereceived power isproduced when thepropeller isrotating (Figs. 
 thc v;ili~e ol  Im (- K) for water is 0.00688 wllcn the wavelength is 10 crn (S band) and 0.0247 for 3.2-cm  wavelength (.Y band)." Eqi~atiori (13.28) is a good approximation for rain attenuation at  S-band or loriger wavelengths. Since rain attenuation is usually small and unimportant at thc  longer wavelengths wl~cre tliis expression is valid, the simplicity offered by the Ravleigh  scattering approximation is of limited use for predicting the attenuation through rain.  -Pl~e compirtation of rain att*wuatioti must thercforc be based on the exact formulation for  splicres as dcvelopcd by Mie.lh Tlic results of such computatlon5 are shown in Fig 13.13 as a  function of tlie wavelcngtll arid the rainrall rate. 
 OF 
 UHF (300 to 1000 MHz). Much of what has been said regarding VHF applies to UHF. However, natural external noise is much less of a problem, and beamwidths are narrower than at VHF. 
 ING COEFFICIENT WORKS  WE NEED TO CONSIDER BOTH THE INCIDENT AND SCATTERED WAVE !T THIS POINT  WE MUST INTRODUCE THE SCATTERING MATRIX  3 4HE RECEIVED FIELD MAY  BE REPRESENTED BY    %%RTE 23 
 TION OF WEAK TARGETS IN CLUTTER AND INTERFERENCE ENVIRONMENTS v IN  )%%% )NT 2ADAR #ONF   ,ONDON     PP n  % 2 "ILLAM  h0ARAMETER OPTIMISATION IN PHASED ARRAY RADAR v IN  2ADAR   "RIGHTON  5+  n  /CTOBER   PP n  ' 6 4RUNK  * $ 7ILSON  AND 0 + (UGHES  ))  h0HASED ARRAY PARAMETER OPTIMIZATION FOR LOW 
 The calculation is summarized in Eq. 5.3.  P S CS D Pr i iri i i r= =×   ∑∑ | | , R e2powerreceived    = −∑centroid extentsquare2 2ED PCri i rr| |2 d d terraintop e stimate , .T C Er r = + ×0 5 (5.3) where Si is a single sum monopulse measurement, Di is the corresponding elevation  difference monopulse measurement. 
 PLANE  -/- 
 (a) Transmitted waveform;  (b) frequency of the transmitted  waverorm; (c) representation of the  time waveform; (d) output of the  pulse-compression filter; (e) same as  (b) but with decreasing frequency  modulation.  the modulated pulse, which is proportional to (sin 11:Bt)/11:Bt. 15 The peak power of the pulse is  increased by the pulse compression ratio !JT after passage through the filter. 
 REFLECTION DIRECTION    SO THEY GIVE STRONG BACKSCATTER ONLY WHEN THE LOOK  ANGLE IS NEARLY NORMAL TO THE SURFACES 2OUGH SURFACES  ON THE OTHER HAND  TEND TO RERADIATE NEARLY UNIFORMLY IN ALL DIRECTIONS  AND SO THEY GIVE RELATIVELY STRONG RADAR RETURNS IN ANY DIRECTION 4HE PROBLEM OF RADAR SCATTER IS COMPLICATED BECAUSE WAVES PENETRATE SIGNIFICANT  DISTANCES INTO MANY SURFACES AND VEGETATION CANOPIES  AND INTERNAL REFLECTION AND SCATTER CONTRIBUTE TO THE RETURN -EASUREMENTS OF ATTENUATION FOR FIELD CROPS   AND GRASSES  SHOW THAT MOST OF THE RETURN IS FROM THE UPPER LAYERS  WITH SOME CONTRIBUTION BY THE SOIL AND LOWER LAYERS IF THE VEGETATION IS NOT VERY DENSE !T # BAND AND HIGHER FREQUENCIES  MOST OF THE SIGNAL RETURNED FROM TREES IS USUALLY FROM THE UPPER AND MIDDLE BRANCHES WHEN THE TREES ARE IN LEAF  n ALTHOUGH IN WINTER THE SURFACE IS A MAJOR CONTRIBUTOR TO  THE SIGNAL !T , BAND  AND ESPECIALLY AT 6(&  THE SIGNAL PENETRATES FARTHER  SO TRUNKS AND THE GROUND CAN BE MAJOR CONTRIBUTORS EVEN WHEN THE TREES ARE LEAFED OUT  !DDITIONAL PROBLEMS OCCUR NEAR GRAZING INCIDENCE  "ECAUSE OF THE LOW ANGLE  WITH THE SURFACE  SHADOWING FREQUENTLY OCCURSSOME PARTS OF THE TARGET ARE OBSCURED  BY INTERVENING PROJECTIONS SUCH AS HILLS AND BUILDINGS 0ARTS OF THE AREA THAT ARE SOME 
 Although theTWTandtheklystron aresimilarinmanyrespects, oneofthemajor differences between thetwoisthatfeedback alongtheslow-wave structure ispossible inthe TWT.butthebackcoupling ofRFenergyintheklystron isnegligible. Ifsufficient energywere fedbacktotheinput,theTWTwouldproduce undesired oscillations. Feedback energymight ariseintheTWTfromthereflection ofaportionoftheforward waveattheoutputcoupler. 
 FAILURES OF   HOURS )T WAS USED IN THE !32 
 isswitched inonly afraction ofthetime; forexample, during theclosing stages ofahoming operation. Itissometimes desirable toprovide anexpanded range scale over an interval atadistance from theradar site without sacrificing anall-round view asanoff-center PPI would do. This may beaccomplished by delaying and expanding therange sweep inanotherwise normal PPI so that aring-shaped area iscollapsed into asolid circle. 
 Almostanyradarcanbeconsidered atracking radar provided itsoutputinformation isprocessed properly. But,ingeneral, itisthemethod by whichangletracking isaccomplished thatdistinguishes whatisnormally considered atracking radarfromanyotherradar.Itisalsonecessary todistinguish between acontillllOlIS crllddtlfj radarandatrack-while-scan (TWS)radar.Theformersupplies continuous tracking dataona particular target,whilethetrack-while-scan supplies sampled dataononeormoretargets.In general, thecontinuous tracking radarandtheTWSradaremploy different typesof equipment. Theantenna beaminthecontinuous tracking radarispositioned inanglebyaservomech­ anismactuated byanerrorsignal.Thevariousmethods forgenerating theerrorsignalmay beclassified assequential lobing,conicalscan,andsimultaneous lohillgormOtlOpulse. 
 TIONS OVER THE )NDIAN /CEAN WITH THE *INDALEE RADAR  EMPLOYING CAREFULLY CALIBRATED TRANSPONDERS  REVEALED ^ D" VARIATIONS IN THE OCEAN SCATTERING COEFFICIENT  DEPEND 
 L.: Polyphase Codes with Good Nonperiodic Correlation Properties, IEEE Trans., vol. IT-9, pp. 43-45, January 1963. 
 -----,...  Video frequencies  30Hz 300Hz 3kH1 roodcost 1-----1  bond 0TH  rodor I  Letter designotions L S C X Ku Ka  ~ I M;,,,.; .... ;., I Submillimeter  For  infrored -- 30kHz 300kHz 3MHz 30MHz 300MHz 3GHz 30GHz 300GHz 3,000 GHz  Frequency  Figure 1.4 Radar frequencies and the electromagnetic spectrum. 
 45. Barton, D. K.: Low-Angle Radar Tracking, Proc. 
 ING ACROSS THE FLOOR OF THE CRATER 3HACKELTON 3UCH ENHANCED REFLECTIONS  ESPECIALLY  IN THE hUNEXPECTEDv SENSE OF CIRCULAR POLARIZATION  ARE INDICATIVE OF VOLUMETRIC RADAR RESPONSE FROM VERY COLD FROZEN VOLATILES SUCH AS WATER 
 Hsiao. J. K.. 
 17.14 isreversed and the original pulses gotothe coder onevezy cycle.. 734 RADAR RELAY [f+iEc. 17.16 The video switch ofFig. 
 LOOKING CASE  AND NEGLECTING THE EFFECTS OF %ARTH ROTATION  THE RADAR 
 CATED ON  §M 
 Asimple scan isone. SEC. 9.7] COMPLEX SCANS 281 inwhich the beam sweeps with but one degree offreedom, that is,it covers repeatedly one and thesame arconthesphere. 
 The logarithm of E to the base 2 is (b\f—M b\]—\—\j bf\ \1+J|M+^l_LJl+...+_JLj (312) (UKJ-. fut UKj_\-.\A Uf) \_^ + ^_LJ£+...+_JLj (3.13) The whole number (N-M) becomes the characteristic, and the series, a frac- tional number, is a line approximation of the mantissa. The approximation is ac- curate to ±0.25 dB if the mantissa contains at least 4 bits. 
 R.: Low Conversion Loss X Band Mixer, Microwar,e J., vol. 21, pp. 53-59, April, 1978. 
 The mismatch  loss is less than 0.1 dB at zero Doppler.     Figure 12.16  Linear Chirp pulse compression system.  . 
 VIEWING ALTIMETERS  IN GENERAL  HAVE LARGE 3.2 4HUS  BANDWIDTH AND LOOKS BECOME THE DRIVING REQUIREMENTS ON SYSTEM DESIGN 4HE EMPHASIS IN THIS SECTION IS ON ALTIMETER PRECISION 3EA 
 For large decimation factors, more than two decimation stages  may be used. A popular filter for the first stage is the Cascaded Integrator Comb14 (CIC) decima - tor filter that can be implemented without multipliers. These filters provide rejection in  the stopband at frequencies that alias to the passband as a result of decimation. 
 Combining the restriction on prf due to unambiguous range Ru with that of Eq. (14.8)  yields  ( 14.9) . This leads to the condition  Ru C -<­<\, -2v OTHER RADAR TOPICS 521  (14.10)  Thus the unamhiguous range and the resolution cannot be selected independently or one  anol her. 
 Nemhauser, and J. W. Sherman: Dynamic Progratnming Applied to Unequally  Spaced Arrays, I EEE Trans., vol. 
 226–231. 123. W. 
 CM BAND AND AT SHORTER WAVELENGTHS  THE EFFECTS ARE APPRECIABLE  BUT AT WAVELENGTHS IN EXCESS OF  CM  THE EFFECTS ARE GREATLY DECREASED )T IS ALSO CLEAR THAT SUSPENDED WATER CLOUD  DROPLETS AND RAIN HAVE AN ABSORPTION RATE IN EXCESS OF THAT OF THE COMBINED OXYGEN AND WATER 
 #/5.4%2-%!352%3   Ó{°£Ç   $IGITAL RECEIVER CHANNEL ERRORS SUCH AS !$# QUANTIZATION  SAMPLEHOLD JITTER  AND  DIGITAL CONVERTER OFFSET    4HE PULSE WIDTH THAT LIMITS THE REACTION TIME OF THE ADAPTIVE SYSTEM  IN ORDER TO  AVOID THE CANCELLATION OF TARGET SIGNAL   4HE TARGET SIGNAL IN THE AUXILIARY ARRAY THAT MAY RESULT IN NONNEGLIGIBLE STEERING OF  THE AUXILIARIES TOWARD THE MAIN 
 69–76, 1976. 124. M. 
 Moreover, the real aircraft trajectories often deviate from the ideal trajectories due to unexpected disturbances [ 12–15] as shown in Figure 1, which leads to the Doppler parameter errors. If the spatially-variant Doppler parameter estimation (DPE) is not considered and left compensated, the SAR image quality will be seriously deteriorated. Thus, it is necessary to perform echo-based DPE to ensure good focusing performance [ 16–21]. 
 . Radar Systems Engineering  Chapter 5 – Resolution and Accuracy  23     5 Resolution and Accuracy   Resolution is a measurement for how close or dense targets may be to each other, while still b e- ing able to separately detect th em.  Under the term resolution the ability is therefore understood  for the separation of neighbouring objects. 
 Magill and Wheeler75 describe the technique in greater detail and present the results of a particular design using simulators. An alumina matching sheet is attractive be- cause it simultaneously provides a natural radome. It should be cautioned that a dielectric sheet in front of the aperture may produce a slow surface wave and a possible null in the element pattern. 
 RADAR ANTENNAS 251  where) is the wavelength in air. Equation (7.21) is always less than unity. At the upper limit of  spacing. 
 Satellite altimeters dedicated to determining the ocean’s large-scale  dynamic surface topography are characterized by absolute sea-surface height (SSH)  1-sec-averaged measurement accuracy on the order of centimeters along tracks of  more than 1000 km, and orbits that retrace their surface tracks every 10 to 20 days.  In contrast, mesoscale missions focus on sea-surface height signals of less than ∼300  km in length. Rather than absolute SSH accuracy, these shorter-scale applications  require precision sufficient to sustain surface slope measurement accuracy on the  order of 1 microradian (one mm sea-level change over a 1-km distance). 
 SPEED BUSSES TO EACH 42 CHANNEL /NE OF THE PRINCIPAL ADVANTAGES OF AN !%3! IS THE ABILITY TO MANAGE BOTH POWER  AND SPATIAL COVERAGE ON A SHORT 
 MENT SYSTEM  WHEREAS THOSE OF AERIAL PHOTOS ARE THOSE OF A DOWN 
 4. Sinnott, D. H.: The Jindalee Over-the-Horizon Radar System, Conf. 
 412 INTRODUCTION TO RADAR SYSTEMS  complex-modulation function whose magnitude I tr(t) ( is the envelope of the real signal, and fo  is the carrier frequency. The received echo signal is assumed to be the same as the transmitted  signal except for the time delay To and a doppler frequency shift fd. Thus  (The change of amplitude of the echo signal is ignored here.) With these definitions the output  of the matched filter is  It is customary to set To = 0 and fo = 0, and to define To - T;( = - TR = TR. 
 D. Howard, “Environmental effects on precision monopulse instrumentation tracking radar at  35 GHz,” in IEEE EASCON ’79 Rec ., October 1979. 56. 
 Van Meter, 0., and D. Middleton: Modern Statistical Approaches to Reception in Communication  Theory, IRE Trans., no. PGIT-4, pp. 
   3/,)$ 
 LATENCY ALSO ALLOWS THE USE OF  #ORRELATED !LERT#ONFIRM (ERE  A 3WERLING  ) TARGET 2#3 FLUCTUATION MODEL IS ASSUMED 4HIS IMPLIES THAT WHEN THE SAME 2& CAR 
 A strip delay line12"15 is made of a long, thin strip of material with transducers at opposite ends. Since the strips must be extremely thin (of the order of a few milli-inches), metal is selected because of its ruggedness. Aluminum and steel are the only metals that have found wide application. 
 The foregoing discussion implies that the broadening ofthe arcs for beacon replies isgreater than that forradar signals. This isnotthecase, however, ifthemaximum range forboth isthesame. IfG~U and G(,oh) aretherespective gains oftheantenna atthecenter ofthepattern and at the maximum ofthefirst side lobe and R!and R;[l.h)the corresponding maximum ranges for interrogation ofthe beacon (to give minimum triggering power), from Eq. 
 16 of"Radar Handbook," M. I. Skolnik (ed.), McGraw­ Hill Book Co., New York, 1970. 
 These footprints cover exactly the same area  for a monostatic radar and will depend on the pulse- and beamwidths, the range, and  the grazing angle. If the footprints are assumed to be of the cookie-cutter  type (constant  amplitude falling sharply to zero at the half-power points), then the relation between the  actual radar clutter cross section s  c, as inferred from the received power via the radar  equation , and the NRCS s  0 is given by  s  0 = s c  /Af (15.7) ch15.indd   7 12/15/07   6:16:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The result allowed an increase  in coherent integration times comparable to monostatic SAR, typically >10 seconds.  Consequently, bistatic SAR image quality was greatly improved, as reported by B.  Rigling in Chapter 10 of Willis and Griffiths.2 Bistatic space-time adaptive processing (STAP) was also developed to improve  MTI performance of separately moving transmit and receive platforms. 
 vol.  MIL-6, pp. 162-169, April, 1962. 
 For example, the radar operator might select a search mode and specify a search  volume that the radar will raster scan, as shown in Figure 4.7. Valid detections in  search are then converted to tracks in the radar computer. These tracks need to be  updated by a track mode on a regular basis depending on the track accuracy required. 
 SPACE PROPAGATION  MULTIPATH INTERFERENCE OR SURFACE REFLECTION   DIFFRACTION  AND TROPOSPHERIC SCATTER .ORMAL3TANDARD 2EFRACTION  4HE REFRACTIVITY DISTRIBUTION WITHIN THE ATMO 
  
 13ecause of its sniall physical aperture a laser radar  is riot suited for most surveillance apl~lications. It is, however, well suited for precision rneasure-  riletit and target iniaging. The rfesigri of a laser radar follows the same general principles as  otlier radars. 
 COMBINED ARCHITECTURES 4HE PHASED ARRAY IS A COMMON EXAMPLE OF THE SPACE 
 M TALL BACKSCREENS   ELEMENTS PER BAND ARRAYS ORIENTED AT n  
 Hanuise: An HF Phased Array Radar for Studying Small-Scale Structure in the High Latitude Ionosphere, Radio Sd., vol. 20, pp. 63-79, January-February 1985. 
 Tronsm~ss~on of T(onsrn~ss~on of  comrnond doto to dolo-dwell(N-1)  rodor for dwell N  Phose shlflers Rooor returrl  bl~lfl21 I>  MOX range "'I1- '0'' Cornrnund  Dolo dwell (N - 1) fro(n dwelt dolo for  Commond I routed, I 1' I (N-1) I I dwell (N + 1)  Comrnun~cal~ons dolo - I '41 ;I' I I  buffer I I ly [ Is full . 1  m~lted Max~rnurn ,  range -- /  t , I ?  I I I  sw~lched for  Beorn lronsm~l  P steer~ng , --- r ?  Dwell (N- 1) C__r_-J  Figure 8.31 Reprcsentativ~. command/rcsponsc scqucncc. 
 532 513. July. 1974. 
 2013 ,23, 142–154. [ CrossRef ] 25. Le, T.S.; Chang, C.P .; Nguyen, X.T.; Yhokha, A. 
 New York, 1%2.  pp. 98-100. 
 Modifications and Additions.-The performance ofthe radar asfinally built was excellent. Some ofthe PPI photographs inthis book, such asFigs. 6.5and 17”21, show the long range, good definition, and relative freedom from ground clutter which characterize theset. 
 Observer must locate itwith 90% certainty. This corresponds toa value ofrv,inTable 2.1,oftheorder of10–1, Ratio ofminimum detectabk sig- nal powertoaveragenm”se power,under above cmditiom. 1,25 (+1 db) Working from Table 2.2, wecaninfer that ifthesystem there described had anover-all noise figure Nof,forexample, 15,thesignal power required attheterminals oftheantenna would beS~im =1.25NkT@ =(1.25)(15) (1.37X10-23)(291)(1.2X10’) =9X10-’4 watts. 
 It was noted that if altitude was reduced rapidly from patrol height on initial contact, locking was possible on large targets such as a submarine beam-on. However, on smaller targets such as a schnorkel or a submarine end-on the reduction in heightalso reduced the size of the echo and locking was impaired. This seems to have been due in part to the nose-down attitude of the aircraft when losing height, causing the target to move out of the centre of the antenna beam, which was not stabilised. 
 367-371, May, 1967.  125. tiering. 
 This  is indicated in Figure 13.2 a. The phase shifters are electronically actuated to permit  rapid scanning and are adjusted in phase to a value between 0 and 2 p rad. With an  interelement spacing s, the incremental phase shift y  between adjacent elements for a  scan angle q0 is y  = (2p /l)s sin q0. 
 Raemer, H. R., and A. B. 
 However, in general, one deals with noise rather than a sinusoidal component. For this reason, the discrete zeros indicated are seldom of interest, and for ease in the computations the signal is assumed to be decorrelated at a frequency// ap- proaching// = c/$R. Some frequencies higher than// cause no problems at par- ticular ranges, but nearby ones do so. 
 Monopulse Track . Phased array radars are well suited for monopulse tracking.  The radiating elements of the array can be combined in three different ways to give the  sum pattern and the azimuth and elevation difference patterns. 
 B. A. Senior, “A survey of analytical techniques for cross-section estimation,” Proc. 
 WEARING COURSE  BUT WILL REDUCE TO CENTIMETERS AT DEPTHS OF ONE METER&)'52%   2ADAR PROFILES ALONG THE CENTERLINE ON &INSTERWALDERBREEN GLACIER AT  n -(Z FROM (AMRAN ET AL              
 vidual elements and their phase shifters (and drivers) can also be checked with this configuration. The phase at each element is sequentially rotated at some low frequency; the amplitude and phase of this modulation as received by the probe relate directly to both the relative amplitude excitation of the element and its rel- ative phase setting.22 Other methods have been proposed23 where measurements are compared with previously recorded ones. Deployment of Apertures. 
 462-468, July, 1971.  40. Loomis, J. 
 Antennas Propagat ., vol. 46, no. 1,  pp. 
 LAYERS CAN GENERALLY BE TREATED AS QUASI 
 Furthermore,  the curvature of the isodops may be  neglected, so the doppler frequency is assumed to  be the same for all maximum-range points and the same for all minimum-range points.  With this assumption,  fv fvd dmax max min minsin sin= =2 2λθ λθ  Thus, the total width of the doppler spectrum is  ∆fv d= −2 λθ θ(sin sin )max min  For short pulses and angles away from vertical, this is  ∆ ∆fv d≈2 λθ θcos  In terms of pulse length, it becomes  ∆fvc hd=τ λθ θ 23cos sin (16.14) If the angular difference across the illuminated rectangle is small enough so that s 0  is essentially constant, the doppler spectrum is a rectangle from fmin to fmax.FIGURE   16. 9 Geometry of doppler-shift calcula - tions for an airborne search radar ch16.indd   16 12/19/07   4:55:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 C. Heimiller, “Bistatic clutter data measurement program,” Environmental  Research Institute of Michigan, RADC-TR-77-389, November 1977, AD-A049037.  98. 
 TO 
   PP n  .OVEMBER   $ # #OOPER AND * 7 2 'RIFFITHS  h6IDEO INTEGRATION IN  RADAR AND SONAR SYSTEMS v  * "RIT )2%   VOL   PP n  -AY   6 ' (ANSEN  h0ERFORMANCE OF THE ANALOG MOVING WINDOW DETECTION v  )%%% 4RANS  VOL !%3 
 BASE JUNCTION APPEARS AS A DELETERIOUS PARASITIC ELECTRICAL COMPONENT  THE EMITTER 
 atid can often last for several se~onds.~ lo Spikes can give rise to excessive false  alart~is in some radar applications. These spikes seem to be associated with breaking waves.  RADAR CLtJn'F.R 477 whichsuchmeasurements canbemade.ThesolidcurvesofFig.13.4a,therefore, aredrawn foreachseparate setofdata.(Asimilarsetcouldbedrawnfor(b).)Thereisalsoasaturation effectevident whenthethreesetsofdataareconsidered separately, butitisnotas pronounced aswhenthethreesetsofdataareconsidered asone.Overtherangefrom10 to20knots, (f0increases atarateofabout0.5dB/kn,Above30knotstheincrease isabout O.ldB/kn.Similarbehavior isexhibited at30°grazing angle.TheeffectofwindatCbandis likethatatXband.Atlowerfrequencies, however, thevariation of(f0withwindisless pronollllced. 
 Advantage istaken ofthe negligible current across thetransition between thefirst and second Quarter-wave sections tomake acontact bearing between theinnermost conductors. This isagreat aid inkeeping the closely spaced tubes allconcentric. Quarter-wave line sections used inthe manner just described toprevent loss ofmicrowave energy into side channels aretermed “chokes.” The nominal characteristic impedance ofthe standard rigid coaxial lines inregular use is50ohms, corresponding toaratio of2.30 forthe radii ofthe inner and outer conductors. 
 no. 349, Mar. 2, 1964. 
 Rept. IER 1 ITSA 1, U.S. De- partment of Commerce, 1966. 
 Thustheoutputofthe quantizer isaseriesofIsandOs.Thisisthenseparated intoseparate rangecellsbytherange First thresholdSecond threshold I •Target pulse Figure10.7Blockdiagram ofabinarymovingwindowdetector, orbinaryintegrator.. III:II:(*TION ot: RADAR SI(;NAI.S IN NOISE 389  gi~tcq, ;rt~rl 111e Is ;irl(l 0s fro111  he ii~st tt $weeps are stored and counted in the binary counter. If  there are at least rt~ Is withir~ the last tt sweeps, a target -is said to be present. 
 The ocean image in Figure 16.46 a shows that the polarization is essentially lin - ear, with the VV signal stronger than the HH. The cross-polarized response shows  essentially no cross-polarized signal for linear transmission, but some for circularly  polarized transmission. For the park shown in Figure 16.46 b, the vertically polarized linear signal is slightly  higher than the horizontally polarized one. 
 AP-32, pp. 252–258, March 1984. (See also correction, vol. 
 I.9  Index terms  Links   Chaff        9.19  radar equation for 9.31  Chebyshev filter bank 15.31  Chinese remainder theorem 17.22  Chirp pulse compression 10.4  Circular polarization in phased arrays 7.6  Clear-air meteorological radars 23.27  Clutter:  in bistatic radar 25.18 25.27  and CW radar 14.3  discrete echoes 17.11  in HF OTH radar 24.6  models, of the ground 12.28  in MTI radar 15.8  in pulse doppler radar 17.9  radar equation for 1.10 2.57  in semiactive missile guidance 19.5  typical values of 15.2  (See also Ground echo; Sea clutter)  Clutter attenuation in MTI radar 15.11  Clutter characteristics in MTI radar 15.8  Clutter filter design in MTI radar 15.23  Clutter filters for MTI radar 15.16  Clutter map 3.53 8.13 8.20  AGC          3.18  implementation of 15.65  Clutter-spectrum standard deviations 15.9  Clutter visibility factor 15.14  Coaxial magnetron 4.7  COBRA DANE 7.76  COBRA JUDY 7.76  This page has been reformatted by Knovel to provide easier navigation. I.10  Index terms  Links   Coherent integration 2.25  Coho         3.16 15.3  Coincidence phase detector 3.37  Collapsing loss 2.54 8.3  Combining:  of power devices in transmitters 4.22  of solid-state devices 5.23  Compact range 6.56 11.40  Complementary sequences 10.21  Composite-surface model of sea clutter 13.32  Computer methods for the range equation 2.62  Cone, radar cross section of 11.10 11.32 11.33   11.45  Cone sphere 11.45 11.46  Conformal arrays 7.3  Conical-scan tracking 18.3  Conopulse    18.21  Corner reflector 11.13 11.14  Correlation processor 10.8  Cosecant-squared antenna 15.69  Cosmos 1500 22.17 22.18 22.23  COSRO        9.27  Coverage diagrams 2.44  Coverage:  of bistatic radar 25.10  of space-based radar 22.12  CPACS        3.49  CPI          15.29  Critical angle, in sea clutter 13.19  Cross-eye    9.27  Crossed-field amplifiers (CFAs) 4.12 4.19  This page has been reformatted by Knovel to provide easier navigation. I.11  Index terms  Links   Crosstalk in tracking radar 18.48  Crowbars     4.40  Cube, radar cross section of 11.25  Cumulative probability of detection 2.60  CW radar:  active stabilization in 14.8  altimeters 14.34  Bessel functions in 14.23 14.38  CFAR in      14.19  for clutter measurement 12.18  clutter noise 14.3  doppler:  filter bank 14.18  navigator    14.37  scatterometer 12.22  tracker      14.18  double sinusoidal modulation 14.26  dual modulation 14.30  feedthrough minimization in 4.3 14.19  and FM       14.21  homodyne in 14.20 14.21 14.31  leakage in 14.30  local oscillator in 14.15  microphonism in 14.7  noise:  from clutter 14.3  measurement of 14.11  modulation 14.28  in transmitter 14.3  personnel detection 14.39  phase coding in 14.29  for police 14.21  This page has been reformatted by Knovel to provide easier navigation. 
 Doppler filter outputs are used  to form main-beam clutter error discriminants for precisely measuring doppler center  frequency to provide fraction of wavelength motion compensation. Main-beam clutter  is not in the same frequency location for each range bin, and so filter output order must  be adjusted to present a common input to the threshold detector. The doppler filter  bank outputs also are applied to a multilevel threshold detector for ground moving  target detection similar to those described in “Ground Moving Target Thresholding.”  Sum and difference discriminant functions are formed and stored in buffer storage for  each detected moving target to improve target tracking and geolocation accuracy. 
 Altitude-line Clutter Blanking.  The reflection from the earth directly beneath  an airborne pulse radar is called altitude-line clutter. Because of specular reflec - tion over smooth terrain, the large geometric area, and relatively short range, this  signal can be large. 
 AgoodADTsystemtherefore requires a radarwithagood,MTLand ..agoQdCEAJ!_.(.ronstant falsealarmrate)receiver. Acluttermap, generated bytheradar,issometimes usedtoreducetheloadonthetracking computer by blanking clutterareasandremoving detections associated withlargepointcluttersourcesnot rejectedbytheMTI.Slowlymovingechoesthatarenotofinterestcanalsoberemoved bythe cluttermap.Theavailability ofsomedistinctive targetcharacteristic, suchasitsaltitude, might alsoproveofhelpwhenperforming trackassociation.71Thus,thequalityoftheADTwill dependsignificantly ontheabilityoftheradartorejectunwanted signals. Whenanewdetection isreceived, anattempt ismadetoassociate itwithexisting tracks.96Thisisaidedbyestablishing foreachtrackasmallsearchregion,orgate,within whichanewdetection ISpredicted basedontheestimate ofthetargetspeedanddirection. 
 Results of simulated experiment. Top left: real part of the simulated (with additive gaussian noise) raw data; top right: First left singular vector as extracted from the SVD decomposition. center left: The 3D version of the ( ×10 interpolated) focused pulse detail of the simulated raw data with the B-SAR algorithm; center right: First right singular vector as extracted from the SVD decomposition. 
 is well suited to the solution of Rayleigh re- gion problems, approximate methods for predicting the RCS of electrically small ob- jects are not presented here. Several approximate methods have been devised for the optics region, each with its particular advantages and limitations. The most mature of the methods are geometric op- tics and physical optics, with later methods at- tacking the problem of diffraction from edges and shadow boundaries. 
 The cathode, RF interaction region, and the.collector are all separate and each can  he designed to perform their required functions independently of the others. In practice,  however. it is found that there are limitations to high power. 
 K. D. Ward, C. 
 25. Ince, W. J.: Recent Advances in Diode and Ferrite Phaser Technology for Phased Array Radars,  pt. 
 with mechanical rotation providing the azimuth scan. The AN/SPS-48, Fig. 8.17, is  such an example. 
 In  this configuration, each input sample is multiplied  by all of the coefficients at once, with the sample  delays between the summer outputs. If the coefficients of a FIR filter are symmetric,  so that the coefficients on either side of the center  of the filter are mirror images of each other (as is  the case with linear phase filters), multipliers can be  saved by adding the samples that get multiplied by  the same coefficient first, thereby requiring about  half as many multipliers, as shown in Figure 25.34  for a 7-tap example.FIGURE 25.32  General IIR filter block diagramτ τa1 a2IN OUTa0 −b1 −b2τ τ FIGURE 25.33  Transposed form  FIR filterτa0 a1 a2IN OUT τ ch25.indd   27 12/20/07   1:40:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The same requirement also relates to  crossed dipole antennas. 21.9 APPLICATIONS It is only possible to provide a brief summary of the wide variety of the applications  for GPR, which has in some cases become an established and routine method of sub - surface investigation. GPR, in the hands of an expert, provides a safe and noninvasive  method of conducting speculative searches without the need for unnecessary disruption  and excavation. 
 Since  the false alarm probability is related to the detection threshold, the latter should be  adapted online based on the intensity of disturbances. Selection of the Waveform.  The benchmark161 includes 8 waveforms, indexed by i  and characterized by a different pulse width te(i), so that the waveform can be selected  in order to provide a SNR greater than the detection threshold and thus maintain an  assigned probability of target detection. 
 But the more distinct the timing mark, the  broader will be the transmitted spectrum. This follows from the properties of the Fourier  transform. Therefore a finite spectrum must of necessity be transmitted if transit time or range  is to be measured. 
 Senior, “Experimental studies of sea surface effects on low angle  radars,” Proc. IEE , vol. 113, pp. 
 98 102. January. 1969. 
 PATH 
 (ILL   P    ! 3 'ILMOUR  *R   -ICROWAVE 4UBES  .ORWOOD  -! !RTECH (OUSE     7 * $ODDS  4 -ORENO  AND 7 * -C"RIDE  *R  h-ETHODS FO R INCREASING THE BANDWIDTH OF HIGH  POWER MICROWAVE AMPLIFIERS v )2% 7%3#/. #ONV 2EC   PT     PP n. 
 20. U.S. Air Force web site, December 2005, http://www.wrs.afrl.af.mil/other/mmf/compres.htm . 
 FACE REFLECTION  THEY EXHIBIT GREAT BANDWIDTH )N GENERAL  A PYRAMIDAL ABSORBER WITH SHARP TIPS AND UNIFORM BULK LOSS CHARACTERISTICS CAN HAVE A BANDWIDTH THAT  EXCEEDS   .ONSPECULAR ABSORBERS NEED NOT HAVE THE GREAT THICKNESS CHARACTERIZED BY SPECU 
 For example, assume  the event in question to be the output voltage v from a radar receiver. Upon obtaining this  voltage, it is of interest to determine whether the output was caused by noise or by signal in the  presence of noise. The probabilities of obtaining noise and signal-plus-noise before the event  takes place are the a priori probabilities. 
 In the electrical-network class of linear-FM waveform generators, a signal is passed through an electrical delay network designed to have a linear delay- versus-frequency characteristic. The most common electrical networks that are used to generate linear-FM waveforms are (1) all-pass networks, (2) folded-tape meander lines, and (3) waveguide operated near its cutoff frequency. The all-pass network is a low-frequency device that uses lumped constant elements. 
 LIMITED CONDITIONS EG  SHORT 
        &)'52%  !LTITUDE ERRORS. 
   
 The signal-to.noise ratio necessary to provide adequate detection is one of the important  THERADAR EQUATION 17 _Thresho~ve~ Rmsvalue ofnoise Q) 0'o-o> Time-- Fi~un'2.1Typical envelope ortheradarreceiveroutputasarunction ortime. A,andB,andCrepresent signalplusnoise.AandBwouldbevaliddetections, butCisamisseddetection. thecrosscorrelation between thereceived waveform andareplicaofthetransmitted waveform. 
 Given the efficiency of simple broadband jamming  and modern ESM, we need to conclude that frequency agility is not of great help  in SAR ECCM. • Pulse coding .167 An effective ECCM against a DRFM repeat jammer is to change  the radar transmitted pulse code from one PRI to another. The radar maintains  the same carrier and bandwidth; however, the pulses are coded to be approxi - mately orthogonal to each other (i.e., their cross-correlation is approximately  equal to zero). 
 Waves ofhigher than critical fre- quent yaretransmitted; those oflower frequency arerapidly attenuated. 1 Corresponding tothecutoff frequency f.isacutoff wavelength A,related tof.byL=c/f. where cisthevelocity oflight. 
 M DIPOLE ANTENNA ORIENTED ORTHOGONAL TO THE ORBIT PLANE IS ONLY WEAKLY DIRECTIVE   WITH A  D" GAIN 4HE TWO  
 storedcluttermap,rawvideo,outlinesofareasofweather blanked bytheoperator, displayofstorednightplans,andtime-compressed displayofseveralsuccessive radarscans. Alsoitcanaidintherequesting ofheight-finder databytheoperator, blanking ofareas containing excessive interference orweather, providing trainingofoperators bysuperimposing simulated targets,andotherfunctions necessary foranair-traffic-control systemorair-defense system.Theoperator cancommunicate inaninteractive manner withthecomputer bysuch meansasakeyboard, lightpen,trackball,orevenvoiceentry.Sometimes anauxiliary CRTdisplay ismounted adjacent tothemainradardisplaytoprovide tabulardataand otherinformation thatwouldotherwise clutterthemaindisplay. Thecharacters andsymbols thatconstitute thesynthetic information maybeinserted onaCRTduringtheradardeadtimeattheendofthesweeppriortothetriggering ofthe nextpulse.Insomesituations theremightbetoomuchinformation tobefullyinserted duringtheavailable deadtime.Inalong-range air-traffic-control radarlocatedinabusyarea theremightbemorethanahundred targetsfordisplay extracted. 
 Phys. , vol. 25,   pp. 
 However, a spike voltage isoften encountered inpractice, asmentioned previously, because ofthe time required forthe magnetron todraw current after thenormal voltage isapplied toit. When itisnecessary toprevent the appearance ofaspike, a“despiking” circuit isused asindicated inthe diagram. The resistance ofthis circuit ischosen equal tothe network. 
 H. Harvey and T. L. 
 Harriger, “Medium PRF for the AN/APG-66 radar,” in Proceedings of the  IEEE,  vol. 73, issue 2, February 1985, pp. 301–311. 
 Filtering prior to the mixer  remains important, however, because the neighboring spurious responses are of rela - tively low order and may produce strong outputs from the mixer. RF filtering is also  important as it reduces out-of-band interference before it can cause intermodulation or  cross-modulation distortion within the receiver. If the receiver operating bandwidth is a large percentage of the RF frequency, some  form of switched or tunable RF filtering may be required so that the image response is  rejected as it moves through the operating bandwidth. 
 For every proposed radar application where beacons would beofuse, the question will arise whether itisbetter touseradar beacons ortoprovide such separate equipment towork atfrequencies setaside forthepurpose. There seems tobenosingle correct answer. Separate cases must be considered separately, but itisdesirable that insodoing the proposed. 
 ) feed displacement, 12.14 feeds for, 12.25 to 12.30 gain optimization, 12.8 to 12.10 mechanical design, 12.35 to 12.41 radomes for, 12.39 to 12.41 role in radar, 12.1 spillover loss, 12. 6 strut blockage, 12.14 to 12.15 surface ace of, 12.10 to 12.14 surface roughness loss, 12. 12 to 12.14 types of, 12.2 Refraction, 14.20, 26.3 to 26.4 Refractivity, 26.3 to 26.4 Refractivity measurements, 19.32 to 19.33 Region of uncertainty (ROU) in target tracking, 7.47 to 7.48 Remote sensing of the environment, 1. 
 Electrons in GaAs travel at approximately twice the speed that is possible in sil-10 ohms 10 degrees10 ohms 10 degrees Inductance in nH Capacitance in pF . icon. In addition, the electron mobility in GaAs is a factor of 3 higher than in silicon. 
 Thesespikesseemtoheassociated withhreaking waves.. According to Longg about half the time the whitecap forms either simultaneously with  the appearance of a radar spike or a fraction of a second thereafter, leading to the conclusion  that the whitecap occurs after the radar spike develops. The greater the duration of the sp~ke,  the greater the size and duration of the whitecap. 
 A sub-array is an aggregation of antenna elementary radiators; the whole  antenna can be considered as an array of these super elements. Adaptive process - ing can be applied at the output signals of each sub-array, thus reducing the system  complexity. Provided that the sub-arrays are configured reasonably, the number of  sub-arrays and the receiving channel errors (e.g, channel mismatching) determine  the cancellation performance. 
 Amitay, R. C. Pecina, and C. 
 43. Zhen, L.; Tan, Y.; Lin, L.; Yu, Z.; Lan, H. Study of land surface composition of Wuhan city based on linear spectral mixture analysis. 
 However it has been shown that the chi-square with m = 2 approximates the Rice when  the dominant-scatterer power is equal to the total cross section of the other, small scatterers,  and so long as the probability of detection is not large.4'  50INTRODUCTION TORADAR SYSTEMS Itisalsocalledthegammadistribution. Instatistics texts,2misthenumber ofdegreesof freedom, andisaninteger.However, whenappliedtotargetcross-section models, 2misnot required tobeaninteger. Instead, mcanbeanypositive, realnumber. 
 4.24 as a function of the standard deviation of the clutter spectrum assuming the spectrum  to he represented by the gaussian function described by Eq. (4.19). The average improvement  for all filters is indicated by the dotted curve. 
 Howard, J. E.: A Low Angle Tracking System for Fire Control Radars, IEEE 1975 It~rer~~i~tionul  Radar Cor!ferrnce, pp. 412-417. 
 Zhang, J. The static small object detection based on ground-based arc SAR. In Proceedings of the 2012 International Conference on Microwave and Millimeter Wave Technology (ICMMT), Shenzhen, China, 5–8 May 2012. 
 These waveforms enable coherent processing of  the received signal, giving additional doppler information that can be used to help  separate targets from clutter. The use of frequency diversity techniques to give added  target detection possibilities becomes potentially affordable, because of the flexibility  of the signal generation technology. Cost has precluded the use of dual-magnetron  transmitters for this purpose. 
 (CHAPTER 21) Daniel Davis, Electronic Systems Group, Westinghouse Electric Corporation (CHAPTER 6) Gary E. Evans, Electronic Systems Group, Westinghouse Electric Corporation (CHAPTER 6) A. Farina, Radar Department, Selenia S.p.A., Italy (CHAPTER 9) Edward C. 
 NOTCH CANCELER  TRACKING TWO SPECTRA AS A FUNCTION OF THE NORMALIZED SPECTRA SEPARATION  $FFR .ORMALIZED SPECTRAL WIDTH RC FR   . 
 This  effect is dw to the nonspherical raindrops which cause the phase shift and attenuation of the  radar energy to be different depending on the direction of polarization. As the radar energy  propagates through the rain, the differential phase shift and the differential attenuation results  in the circular polarization being converted to elliptical polarization. By selecting the optimum  elliptical polari~ation, it lias bee11 said that the cancellation in some regions of" heavy raiti"  might be increased by as much as 12 dB over that obtained with circular p~larization.~'  However, the polarization that is optimum for one particular region might actually prove to  be worse than the cancellation obtained with circular polarization in some ather region. 
 83. C. Nakos, S. 
 The low insertion loss also means that an RF signal traveling in the reverse direction from  output to input suffers little attenuation. A high-power circulator or other isolation device may  be required between the CF A and its driver to prevent the power reflected from the output of  the CF A building up into oscillations or interfering with the driver stage.  The gain of conventional pulsed crossed-field amplifiers is typically between 10 and  17 dB. 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 25.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 a receiver and ADC are behind every element. In this system, the time delay is imple - mented either as a digital phase shift or digital time delay, followed by a digital summer. 
 PGI-4, pp. 23–30, 1955. 90. 
 TION  LEADS TO A WAVELENGTH SELECTION IN THE RANGE OF  TO  CM FOR MOST PRECIPITATION BASED APPLICATIONS. 
 Such conformal arrays have  been considered for radar but they do not appear suitable for general application. They have  also been examined for I FF and air traffic control interrogation antennas.132  A serious competitor to the cylindrical array is a number of planar arrays arranged to  approximate the cylinder. This is a much simpler system and is quite practical. 
 211-216, April. 1957.  56. 
 ch14.indd   40 12/17/07   2:47:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 
 16 INTRODUCTION [SEC. 1°7 Microwave Committee persuaded the Massachusetts Institute ofTech- nology toaccept theresponsibility ofadministering thenew laboratory, The Radiation Laboratory, asitwas named, opened itsdoors early in November 1940. The director ofthe laboratory throughout its62 months oflifewas Dr. 
 RADAR ANTENNAS 235  Broadband signals. The Fourier-i~itegral-transform relationship between the radiation pattern  E(4) and the aperture distribution A(z) as expressed in Eqs. (7.11) and (7.14) applies only  when the signal is a CW sine wave. 
 and G. W. Farnell: A Homogeneous Dielectric Sphere as a Microwave Lens, Can. 
 Geosci. Remote Sens. 2014 ,52, 1856–1868. 
 Although the Reggia­ Spencer phase shifter has been successfully' applied in operational radar and was one of the  first practical phase shifters suitable for radar. in its present form it has been largely superseded  hy other devices.  Latching ferrite phase shifters.°' 1 · B The use of a ferrite in the form o[ a toroid centered within a  waveguide as in Fig. 
 Ref. [ 11] presents a schematic diagram of imaging geometry for an idealized anticyclonic eddy, as shown in Figure 1. A dark line appears on the upper left and lower right portions of the eddy, and a bright line on the lower left and upper right of the eddy. 
 CFAs can be used as a power booster following a magnetron oscillator, as ttie higtt-power  stage in master-oscillator power-amplifier (MOPA) transmitters with other CFAs or a TWT  as the driver stage, or as the individual transmitters of a high-power phased-array radar.  208INTRODUCTION TORADAR SYSTEMS tothoseoftheklystron, buttheyaregenerally moredifficult thanfortheklystron. In50111(; traveling-wave tubeswithcoupled-cavity circuits; oscillations appearforaninstanlduring th(; turn-onandturn-offportions ofthepulse.1Theyarecalledrabbit-ear oscillations becauseof theircharacteristic appearance whentheRFenvelope ofthepulsewaveform isdisplayed visually onaCRT.Thesecanbeundesirable insomemilitary applications sincetheymight provideadistinctive featureforrecognizing aparticular radar. 
 An individual cell might have a life of  from 15 to 30 minutes. The cells can drift with the wind and align themselves in "streets."  Much of the knowledge of the hehavior of convective cells has been obtained from radar  measurements.70·10~ inR  An atmospheric layer is a stratum within which the mean vertical gradient and/or the  variance of rdractive index arc much greater than elsewhere. Layers may be from a few meters  to more than a hundred meters in vertical thickness and might extend in the horizontal from  about one kilometer to several tens of kilometers. 
 Other Models and Propagation Issues.  Studies of HF radar performance at  low latitudes have shown that it is often necessary to incorporate models of dynamical  processes, either because they manifest themselves directly in the doppler structure  of radar echoes or because they are indicators of other phenomena that do. Useful  models in this category include HWM93,57 which describes the structure of the zonal  and meridional neutral winds throughout the ionosphere, and WBMOD,58 which  describes scintillation arising from small scale irregularities such as those associated  with spread-F in the post-sunset ionosphere. 
 Mag. 2005 ,47, 19–34. 18. 
 ................................ ..............  6  Radar Waveforms Minimum Range  ................................ 
 AP-15, pp. 820-821, November 1967. 129. 
 42. Schaper, L. W., Jr., D. 
 In pulse doppler  applications, spurious signals are of much greater concern because they can create  components with doppler at a variety of frequencies that may not be rejected by the  clutter filtering. Signal-to-Noise-and-Distortion Ratio (SINAD).  SINAD is the rms signal ampli - tude to the rms value of the A/D converter noise plus distortion. 
 In Fig. 20.5d, RF or IF hybrids are used to combine the sum and delta channels in quadrature, i.e., with a 90° phase shift. An accurate phase detector then detects the phase difference between the two channels. 
 Range- and Range Rate Ambiguity Resolution.  To apply the SVC algorithm,  true range and radial velocity (range-rate) must be determined from the range-ambig - uous and doppler-ambiguous waveform. This requires multiple detections from the  same target. 
 (This is similar to  the description of surface reflections and its effect on the elevation coverage, as in Sec. 12.2.)  The direct and the surface-reflected signals combine at the radar to .J'kld_an angle measure­ ment that differs from the true measurement that would have been made with a single target in  the absence of surface reflections. The result is an error in the measurement of elevation. 
 ATED POWER IS FUNDAMENTAL TO THE DESIGN OF SOLID 
 AMPLITUDE MOV 
 A goal of 0.1 dB accuracy is perhaps reasonable, although admittedly it may be impossible to evaluate all the factors in the equation with that degree of precision. Historical Notes. Possibly the first comprehensive treatise on radar maximum-range prediction was that of Omberg and Norton,1 published first as a U.S. 
 18.30  Dual-Band Monopul se  .......................................  18.31  Mirror Antenna (Inverse Cassegrain)  ..................  18.32 On-Axis Tracking  ............................................... 
 TIONAL RADARS IS TO TRANSMIT BOTH HORIZONTAL AND VERTICAL POLARIZATIONS SIMULTANEOUSLY WHILE INDEPENDENTLY RECEIVING BOTH ORTHOGONAL SIGNALS FOR POLARIMETRIC PROCESSING  ALLOWING RECEPTION OF THE IMPORTANT CO 
 . Radar System Engineering  Chapter 12 – Selected Radar Applications  153     13.3.8  ACC Sensor System Specification   The following spe cifications for the frontends of future ACC Radar sensors are being strived  for [Sch]:     Frequency  f 76,5 Ghz  Transmitting power  PT 22,5 mW  Antenna gain  G 35 dB  No of beams   5  Pulse duration  τ 6,7 ns  IF bandwidth  B 150 MHz   Noise figure  F 7 dB  Pulse repetition frequency  PRF 71 kHz  Processing gain  NFFT 512    Table 13.4  Sensor system specifications for 76 GHz ACC Radar.   13.3.9  MMIC Integration   In previous years there have been many high -integrated chips for ACC and other vehicle se n- sors developed by several companies. 
 17 “Use of space systems for planetary geology and geophysics,” San Diego: American  Astronautical Society, 1968, pp. 447–448.  94. 
 , 
 A fewdecibels improvement inreceiver noise-figure canbeobtained atarelatively lowcostas compared tothecostandcomplexity ofaddingthesamefewdecibels toahigh-power transmitter. Thereare,however, limitations totheuseofalow-noise front-end insomeradar applications. 7A~mentioned above,thecost,burnout, anddynamic rangeoflow-noise devices mightnotbeacceptable insomeapplications. 
 The reflection coefficient from a mismatched antenna with a voltage­ standing-wave ratio <J is IP I = (<J -1)/(<T + 1). Therefore, if an isolation of 20 dB is to be  obtained, the VSWR must be less than 1.22. If 40 dB of isolation is required, the VSWR must  be less than 1.02. 
 (a) Vertical polarization.  (h) horizontal polarization. Two curves are shown for Phoenix: one is for a sample size of 1000 and  corresponds to the downtown area. 
 HOUSE MANUFACTURING CAPABILITY FOR HIGH 
 16-2A to 16-2F. Sept. 26-28. 
 BASED APPLICATIONS  THE DISPLAY OF !2%03  TACTICAL DECISION AIDS FOLLOWED SUIT /NE SUCH WEB 
 16.1 is a convolution integral; the figure shows the  convolution of the beam pattern with the s 0 curve. Clearly, the average at the vertical  is lower than it should be to indicate properly the variation of s 0 near the vertical. Figure 16.19 shows an example91 based on the theoretical scattering coefficient for  the sea derived from the spectra reported by the Stereo Wave Observation Project.92  The effect of different beamwidths is clearly  shown. 
 The reason that the source phase noise is not critical to the measure- ment is that it is common practice to add sufficient coaxial or microwave delay to equalize the two paths to the phase detector. Figure 14.2 indicates what such equalization (i.e., correlation) buys. As above, the amplitude modulation intro- duced by the source or the component under test must be checked first. 
 21.) esis is true; PB is a function of the jammer-to-noise ratio (JNR) value, the blank- ing threshold F9 and the gain margin p = GAIGsl of the auxiliary antenna with respect to the radar antenna sidelobes. (2) The probability PFA of false alarm, which is the probability of associating the received signals (w, v) with the hypoth- esis H1 when the true hypothesis is #0; PFA is a function of the detection thresh- old a normalized to the noise power level and of the blanking threshold F. (3) The probability P0 of detecting a target in the main beam, which is the probability of associating the received signal (u, v) with H1 when the same hypothesis is true; P0 depends, among other things, on the signal-to-noise power ratio SNR, PFA, and the blanking threshold F. 
       AND THE THREE 
 R. E. Kell, “On the derivation of bistatic RCS from monostatic measurements,” Proc. 
 M RESOLUTION AT 8 BAND -AJOR ADDITIONAL OBJECTIVES INCLUDE LARGE AREA COVERAGE AS WELL AS HIGH RESOLUTION  WHICH IMPLY 3CAN3!2 AND 3POT3!2 MODES  RESPECTIVELY 4HE  
 PORT HYBRID JUNCTION 4HE TRANSMIT 
 HUNDREDTH OF THE 02& WOULD YIELD A  D" IMPROVEMENT FACTOR FOR A DOUBLE CANCELER WITH AN INPUT CLUTTER  SPECTRUM WHOSE WIDTH  &)'52%  "LOCK DIAGRAM OF A RADAR ILLUSTRATING THE SIGNAL FLOW PATH OF THE 4!##!2 CONTROL LOOP. 
 The greatest phase-quantization lobes seem to occur with a phase slope such  that the elements are spaced by a distance exactly one-half of the period or an exact  odd multiple thereof. The phase error under this condition has element-to-element  phase ripples with a peak-to-peak value of α π=/2p. The value of the peak phase- quantization lobes for the case shown in Figures 13.21 f and 13.22 are given in  Figure 13.23. 
 Mooney, “Post Detection STC in a Medium PRF Pulse Doppler Radar,” U.S. Patent  4,095,222, June 13, 1978. 46. 
 Lhermitte and Atlas72 were the first to show how a sin- gle doppler radar can be used to measure vertical profiles of horizontal wind. This technique can be used if the precipitation and the wind are uniform in the region scanned by the radar. The method depends upon an analysis of the radial velocity measured during a complete scan in azimuth with elevation angle fixed. 
 E. Sollenberger: Optimum Pulse-Time Determination, I RE Trans., no.  PGIT-3, pp. 
 Anderson, “A microwave technique to reduce platform motion and scanning noise in   airborne moving target radar,” IRE WESCON Conv. Rec ., vol. 2, pt. 
 Although tracking radars based upon the phase-comparison monopulse principle have  been built and operated, this technique has not been as widely used as some of the other  angle-tracking methods. The sum signal has higher sidelobes because the separation between  the phase centers of the separate antennas is large. (These high sidelobes are the result of  qrcltirrq lohcrs. 
 These valves are similar in electrode  construction to a hard triode, but they contain a minute  quantity of some inert gas. Immediately this gas ionizes  the anode current rises to an extremely high value.  There are small gas-filled thyratrons which have a  cathode rating of only 5 watts, yet on ionization they are  capable of passing I ampere of anode current. 
 STATE SENSING  USING THE *).$!,%% SKYWAVE RADAR v  )%%% * OF /CEANIC %NGR   VOL /% 
 This principle was applied with great profit to the Magellan  SAR design,114  as illustrated by Table 18.7. From that table, one can verify that the image quality of  Magellan  data varied by no more than ∼±2% pole to pole, in spite of large variations  in radar range, incident angle, and ground range resolution. Data Rate . 
 For example, it is certainly true that a mechanically scanned reflector antenna cannot  switch a beam from one direction to another as fast as can a phased-array antenna. However,  it is seldom, if ever, that the operational requirements do not permit the system designer to  configure a system to do an equivalent job with a mechanically scanned antenna.  An N-element array can, in principle, generate N independent beams. 
 In a practical array, the impedance  variation depends upon the feed system and the phase shifter. If these are taken into  account, the impedance variation may be different from what the above model might  predict. In most analyses, only the coupling at the aperture is considered. 
    PP n  -AY   ' ,INDE  h! SIMPLE APPROXIMATION FORMULA FOR GLINT IMPROVEMENT WITH FREQUENCY AGILITY v  )%%%  4RANS  !%3 
 The elevation angle is positive above  the horizon (0° elevation angle), but negative below the  horizon.     Height     The height of a target over the earth's surface is called  height or altitude. This is denominated by the letter H  (like: Height) in the following formulae and figures. 
 GATE RANGE 
 CRAFT VELOCITY  AND THE NUMBER OF DIGITAL BITS PER DATA SAMPLE /F COURSE  MEAN DATA RATE CAN BE RELAXED IF THE DATA FROM ANY GIVEN PASS CAN BE COLLECTED AND THEN PLAYED BACK AT A SLOWER RATE !LTHOUGH THIS STRATEGY WAS EXPLOITED BY THE  -AGELLAN DESIGN   TOLERANCE FOR WHICH WAS SET UP BY THE ELLIPTICAL ORBIT  IT WAS  NOT SUFFICIENT TO SOLVE THE  LIMITED DATA 
 102. R. K. 
 -1, 
 ' #LASS 
 BORNE APPLICATIONS  AS COMPARED TO THE LINEAR 
 DOPPLER CELL IN THE  3 CHANNEL  THE 0$) OUTPUT IS COMPARED WITH A DETECTION THRESHOLD  DETERMINED BY A CONSTANT 
 FED REFLEC 
 Y . Abramovich, S. J. 
 Remote Sens. 1999 ,37, 2198–2214. [ CrossRef ] 20. 
 PORT APERTURE ON RECEIVE ENABLES A CLUTTER SUPPRESSION INTERFEROMETRY TECHNIQUE THAT ALLOWS THE OPERATOR TO DETECT  ACCURATELY LOCATE  AND TRACK SLOW MOVING GROUND TARGETS IN THE PRESENCE OF COMPETING GROUND CLUTTER  2AYTHEON #OMPANY 0HASED !RRAY 2ADARS  #OURTESY OF 2AYTHEON #OMPANY  0!42)/4 4HE 0!42)/4 IS A MULTIFUNCTION PHASED ARRAY RADAR SYSTEM DEVEL 
 Hansen (ed.), Academic Press, New York, 1966.  52. Alday. 
 Although more complex and expensive than a normal klystron, the clustered-cavity klystron is still less complex and costly than a comparable TWT or Twystron. Traveling-Wave Tubes (TWTs). The low-power helix TWT is still the king of bandwidth. 
 66. Anderson, D. B.: A Microwave Technique to Reduce Platform Motion and Scanning Noise in Air-  borne Moving-Target Radar, IRE WESCON Conv. 
 BOUNCE  FLAT 
    
 Simple Objects.  Because of its pure radial symmetry, the perfectly conducting  sphere is the simplest of all three-dimensional scatterers. Despite the simplicity of its  geometrical surface, however, and the invariance of its echo with orientation, the RCS  of the sphere varies considerably with electrical size. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation.  THE PROPAGATION FACTOR, FP, IN THE RADAR EQUATION  26.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 APM considers almost every environmental effect, making it a highly desirable model  for use in complex assessment systems.TABLE 26.2  Propagation Effects Modeled by APM Propagation Eff ects Mechanisms Range-dependent refractiv e conditions Variable terrain Multi-path Diffraction Terrain masking Troposcatter Rough (Sea) surf ace HF surf ace wave Range-dependent dielectr ics Obstacle gain Surface clutter Gaseous abosr ption Rain attenuation VegetationDue To Environment APM 2.0.01 Sea Terrain Atmosphere FIGURE 26.8  APM submodel regionsFlat Ear th (FE) Ray Optics (RO) Extended Optics (XO) Parabolic Equation (PE) RangeHeight ch26.indd   17 12/15/07   4:53:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 DETECTOR OUTPUT VOLTAGE  ¨3¨   MAGNITUDE OF SUM SIGNAL  ¨$¨    MAGNITUDE OF DIFFERENCE SIGNAL  P    PHASE ANGLE BETWEEN SUM AND DIFFERENCE SIGNALS 4HE DOT 
 recommendation to set the trim 1 °or 2 °nose-down when ﬂying with a full war load. No heading control adjustment was provided and this was set up on the ground. It was recommended that tuning be undertaken with the echo box (wavemeter) toavoid stopping the scanner to point at a strong target (such as land), as this could cause desynchronization of the scanners. 
 Liebman, P. M .. L. 
 To give an example of interpulse stability requirements, consider a 3000-MHz  radar transmitting a CW pulse of duration t = 2 µs and the requirement that no  single system instability will limit the MTI improvement factor attainable at a range  of 100 nmi to less than 50 dB, a voltage ratio of 316:1. The rms pulse-to-pulse  transmitter frequency change (if a pulsed oscillator) must be less than  ∆f= =1 316504πτHz (2.50) which is a stability of about 2 parts in 107.Pulse-to-Pulse Instability Limit on Improvement Factor Oscillator phase noise See discussion in text . Transmitter frequency I = 20 log [1/( p ∆f t  )] Stalo or coho frequency I = 20 log [1/(2 p ∆f T)] Transmitter phase shift I = 20 log (1/ ∆f) Coho locking I = 20 log (1/ ∆f) Pulse timing I = 20 log [ /( ) ] τ τ 2∆t B Pulse width I = 20log [ /( ) ] τ τ∆PW B Pulse amplitude I = 20 log ( A/∆A) A/D jitter I = 20 log [ ( )] τ τJ B A/D jitter with pulse compression following A/D I = 20 log [ /( ) ] τ τJB where ∆f interpulse frequency change       t transmitted pulse length       T transmission time to and from target       ∆f interpulse phase change       ∆t time jitter       J A/D sampling time jitter       Bt time-bandwidth product of pulse compression        system ( Bt = unity for CW pulses)       ∆PW pulse-width jitter       A pulse amplitude, V       ∆A interpulse amplitude changeTABLE 2.5  Instability Limitations ch02.indd   72 12/20/07   1:46:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Circular SAR (CSAR) can detect the scattering variation under different azimuthal look angles by a 360-degree observation. Different targets usually have varying degrees of anisotropy, which aids in target discrimination. However, there is no effective method to quantify the degree of anisotropy. 
 108, no. C9, p. 3295, 2003. 
 In addition, there may be anomalous ionization referred to as sporadic E. This latter ionization layer is thin in altitude, may be either smooth or patchy, is seasonally and diurnally variable but not well correlated with solar activity, and has marked variation with latitude. 3. 
 Appl. Remote Sens. 2016 ,10.[CrossRef ] 35. 
 STATE VERSION OF THE 303 
 Atverticalincidence thereislessbackscatter fromlandthanfromsea,butthisis usuallyundesirahle sinceitreduces therangeofradaraltimeters overland. Landclutterisdifficulttoquantify andclassify.Theradarechofromlanddepends onthe typeofterrain.asdescribed byitsroughness anddielectric properties. Desert,forests.vegeta­ tion,haresoil,cultivated fields.mountains, swamps, ·cities.roads,andlakesallhavedifferent scattering characteristics. 
 D. Lunden: A Slotted Radome Cap for Rain, Hail, and Lightning Protection,  Microwave J., vol. 11, pp. 
 Tlie accuracy of precision range measuring systems that utilize  pliase mensurements, as in the Tellurorneter (Sec. 3.5), also can be amected by the evaporation  dact." On the positive side, the evaporation duct, when used with a properly sited antenna,  car1 provide extended range against surface targets or low-flying aircraft considerably beyond  tliat wliich would be expected from a uniform atmosphere.  Prediction of refractive effects. 
 The small differences between “Poker Flat ISR” and “Poker Flat ISR (average)” further verify the stable circumstance of the ionosphere. 4.2. Modeling the T opside Proﬁle of Ionosonde with New H T We have demonstrated that PolSAR data can be used to estimate the TEC under 700 km with a considerable precision within 1 TECU. 
 Pub. no. 490, Edinburgh, UK,  October 15–17, 2002, pp. 
 A pol>ulnr for111 of slow-wave structure for liigli-power TWTs is the coupled-cat-it)*  circuit '.' it is not derived froni the lielix as are the ring-bar or ring-loop circuits. Tlie  iridividiial unit cells of the coupled-cavity circuit resemble the ordinary klystron resonant  c;ivities Therc is tio direct couplirig between the cavities of a klystron; but in the traveling-  wave tuhe, coupling is provided by a long slot in the wall of each cavity. The coupled-cavity  circuit is quite conipatible witti ttie use of lightweight PPM focusing, a desired feature in some  airborne applicatio~is. 
 3.  78. Stark, L.: Comparison of Array Element Types, "Phased Array Antennas, Proceedings of the 1970  Phased Array Antenna Symposium," Artech House, Inc., Dedhanl, Mass., 1972, pp. 
 To use  the equality of Eq. (14.13) in Eq. (14.15), write A, = p, A, where p, = antenna aperture  efficiency, and A = physical aperture area assumed to be rectangular of width D and height H. 
 More detailed descriptions of GTD/UTD can be found in various references.45,46 Full-Wave Reflector Analysis Methods.  Rigorous or full-wave methods include,  for example, the method of moments (MOM), the finite element method (FEM), and  the finite difference time domain (FDTD) method. Although these methods are very  rigorous and highly accurate, they are not generally employed for reflector design/ analysis because they tend to be too computationally intensive. 
 pp. 660 665. Scptcm-  ber, 1965. 
 448 INTRODUCTION TO RADAR SYSTEMS  Rodar l \~~-<Radar ray in the presence of refraction  ___ ........ ___ -...., .;_ _,,,,/ Rodar roy in the absence 01 retracrion  Rodar horizon in the  absence of refraction  Rodar Rodar horizon in the  presence of refraction  (a)  (b) Apparent  target  position  True  target  pos'ition J  Figure ll.5 {«) Extension of the radar horizon d\1e to refraction of rndar waves hy the atmosphere: (/.}  angular error caused by refraction.  th1..: radar coverage (Fig. 
 [ CrossRef ] 6. Zhang, Y.; Sun, J.; Lei, P .; Li, G.; Hong, W. High-resolution SAR-based ground moving target imaging with defocused ROI data. 
 This may  be done by adding a constant phase shift in the path to each radiator, with a value  that differs from radiator to radiator by amounts that are unrelated to the bit size. FIGURE 13.21  Effects of periodic amplitude and phase modulation (sin q1 = sin q0 ± l /s) ch13.indd   36 12/17/07   2:40:35 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 2#3 MISSILE  WHILE ALSO RETAINING THE LARGER CROSS 
 TO 
 S. Dorr: 3-D Radar Based on Phase-in-Space Principie.  IEEEtTrans.. 
 CIENCY CONTINUE 0HASED ARRAYS CAN BE CONTROLLED ADAPTIVELY  PARTICULARLY FOR SIDELOBE CANCELLATION 4HIS IS AN AREA WHERE THEORY AND UNDERSTANDING HAVE ADVANCED MUCH !LSO GREAT PROGRESS HAS BEEN MADE WITH INDOOR NEAR 
 The nonlinear-FM waveform with constant-amplitude time envelope provides a com­ pressed waveform with low time-side lobes at the output of the receiver matched-filter without  the 1-to 2-dB penalty obtained with the. linear-FM waveform and mismatched filter. 16•24•32  The non linear variation of frequency with time has the same effect as amplitude-weighting the  transmitted-signal spectrum, while maintaining the rectangular pulse-shape desired for  efficient transmitter operation. 
 ENT RADAR STABILITY LIMITATIONS  APART FROM ANY ADDITIONAL COHERENT GAIN  IT IS SOMETIMES PREFERABLE TO USE THE )%%% DEFINITION OF CLUTTER ATTENUATION )N THIS CHAPTER   IMPROVEMENT  FACTOR AND  CLUTTER ATTENUATION WILL BE USED SYNONYMOUSLY 7HEN THE COHERENT GAIN OF THE  DOPPLER FILTER IS INCLUDED  THE TERM SIGNAL 
 TYPE MODULATOR USES A DELAY LINE OR A PULSE 
  AND 66 
 INTERNAL NOISE RATIOS )T HAS BEEN WIDELY ARGUED THAT THE INEVITABILITY OF TIME 
 /\.slightlymorecomplex modelthanthetwo-scatterer targetconsidered aboveisone consisting ofmanyindividual scatterers, eachofthesamecrosssection,arranged uniformly alongalineoflengthLperpendicular tothelineofsightfromtheradar.Theresultant cross sectionfromsuchatargetisassumed tobehaveaccording totheRayleigh probability distribu­ tion.Theprohahility oftheapparent radarcenterlyingoutside theangular regionofLIR radians(indnetrackingplane)is0.134,whereRisthedistance tothetarget. 32Thus13.4per­ centofthetimetheradarwillnotbedirected toapointonthetarget.Similar resultsfora two-dimensional modelconsisting ofequal-cross-section scatterers uniformly spacedovera circular areaindicate thattheprobability thattheapparent radarcenterliesoutsidethistarget is0.20. Anglefluctuations inatracking radararereduced byincreasing thetimeconstant ofthe AGesystem(reducing thebandwidth).29.33.34 However, thisreduction inanglefluctuation is accompanied byanewcomponent ofnoisecausedbytheamplitude fluctuations associated withtheechosignal;thatis,narrowing the/\.Gebandwidth generates additional noiseinthe vicinity ofzerofrequency, andpoorertracking results. 
 Another is that the weight of the transmitter is now added to that of the  218INTRODUCTION TORADAR SYSTEMS energy(typically 10to15keY).Onstrikingthediode,whichisreversebiasedwellbelowthe avalanche threshold, eachimpacting electrongivesrisetothousands ofadditional carrierpairs toprovideacurrentamplification of2000ormore.Acontrolgridisinserted between the cathode andthediodetodensity-modulate theelectron beam.(Thebasicgeometry issimilar tothatoftheclassictriodevacuum tube,butwithasemiconductor diodeastheplate.) TheEBScanalsobedeflection-modulated byvaryingthepositionofthebeamrelativetotwo ormoreseparated semiconductor targetswhoseoutputsarecombined. TheEBSisclaimedto bebroadband andtohavehighgain(25to35dB),highefficiency (50percent), andlonglife.At 1GHz,anEBSamplifier mightbecapableofapeakpowerof2to3kW,andanaverage powerofabout200W.TheEBShasdecreasing capability atthehigherfrequencies. Alimita­ tionoftheEBS,notfoundwithothersemiconductor devices, isthatitrequires apowersupply of10to15kVaswellasacathode heatersupply. 
 The apparent velocity varies linearly along the aperture.  Hence, the two-way aperture distribution is mapped into the frequency domain. The  resulting power spectrum due to the antenna scanning is  H f Fffa( )=   ≤ ≤220λ θθ λ   (3.15) where θ = antenna rotation rate  a = horizontal antenna aperture This spectrum can be approximated by a gaussian distribution with standard deviation  σθ θθ λcr af na= = ≈ 0265 0265 0265 . 
 Res. 2014 ,102, 18–35. [ CrossRef ] [PubMed ] 4. 
 Equation (8.6) is only an approximation, which rnay be seriously inadequate for many  problems of array design. It should be used with caution. It ignores mutual coupling, and it  does not take account of the scattering or diffraction of radiation by the adjacent array  elements or of the outward-traveling-wave coupling.12 l4 These effects cause the element  radiation pattern to be different whe~ located within the array in the presence of the other  elements than when isolated in free space. 
 J. Burke, B. J. 
 The resolution of the processed image in the time (range) domain is inversely  proportional to the bandwidth of the emitted waveform. The resolution in the cross- range domain is inversely proportional to the aspect angle window over which the  data are collected. Thus, the operating characteristics of the instrumentation system  and the azimuthal data sampling rate must be decided before the data are collected. 
 TIONS CAN ALSO BE USED BY #ANADA  !USTRALIA  .EW :EALAND  AND THE 5NITED +INGDOM 3PECIAL BLOCKS OF NUMBERS ARE RESERVED FOR THESE COUNTRIES &URTHER INFORMATION CAN BE FOUND ON THE )NTERNET UNDER -), 
     CAN BE ASSUMED TO BE APPROPRIATE UNDER CONTINUOUS RAINFALL CONDITIONS 2 IS THE SUR 
 Chait: Ferritcs at Microwaves, Proc. IRE, vol. 41, pp. 
 The ability to form many beams is usually  easier on reception than transmission. This is not necessarily a disadvantage since it is a useful  method of operating an array in many applications.  The simple linear array which generates a single beam can be converted to a mulliple­ beam antenna by attaching additional phase shifters to the output of each element. 
 Hi28S and all the systems such as ASV, which give ir  the aircraft cockpit a television-like picture of the terrair  below, took their rise in the fateful autumn of 1941. Ths  comparative failure of our bombing effort over Germany  at that time was very much in the minds not only of th  operational Service heads, but of the technicians respon.  sible for the radar devices then in use. 
 RADAR CROSS SECTION  14.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 Test ranges designed to exploit the multipath effect may be asphalted to improve  the ground reflection, although many ranges are operated over natural soil. Paving the  range ensures uniformity in the characteristics of the ground plane from day to day and  extends its operational usefulness to higher frequencies than might otherwise be pos - sible. A conducting screen embedded in the asphalt may improve the reflection. 
 Its detection performance is only 0.15 dB less efficient than the optimum.66  The recirculating delay-line integrators of Fig. 10.10 can be used to obtain an estimate of . 392 INTRODUCTION TO RADAR SYSTEMS  the angular location of the target. 
 25.5  25.4 Range Relationships  ..............................................  25.6  Range Equation  .................................................  25.6  Ovals of Cassini  ................................................. 
 1968.  34. llarrison, A.: Marine Radar Today -A Review, Tlre Radio utrd Electrorric E~rginver, vol. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.50  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 Figure 2.51 shows the effect of the returned signal if the point clutter exceeds the  IF limit level by 6 dB. When the signal reaches the limit level, there is a step increase  of residue of about 30 dB. 
 Lucas, D. L.: Ionospheric Parameters Used in Predicting the Performance of High Fre- quency Skywave Circuits, Interim Report on NRL Contract N00014-87-K-20009, Ac- count 153-6943, University of Colorado, Boulder, Apr. 15, 1987. 
 The noise and spurious signals generated by a CF A can be quite low when the tube is  locked in and controlled by an RF drive signal.17 Measurements of noise made with the  voltages applied but with the tube inactive because of no RF drive-signal, indicate the noise to  approach what would be expected from its thermal level. Intrapulse noise is generally much  higher. Spurious signals can also arise during the flat part of the pulse. 
 PARISON OR AMPLITUDE COMPARISON   CONICAL 
 InISAR 3-D imaging based on CS technology has the following advantages: (1) high-resolution ISAR images can be obtained only by short-time observation data. At the same time, rotation of the target can be approximately considered to be uniform in short-phase processing interval and thus the occurrence probability of range cell migration is reduced; (2) imaging results are not affected by sidelobe, and image resolution can be improved by increasing imaging grids, so that it is helpful to suppress angular glint phenomenon in InISAR imaging and (3) through the CS technology, the ISAR images can be further reconstructed by adopting sparse sampling data, thus reducing the pressure of data acquisition. In interferometric imaging, compressed sampling and sparse reconstruction can be separately performed for each channel, so as to reduce the system sampling rate and improve the quality of radar imaging. 
 R. D.: Application of Frequency Modulation Techniques to Doppler Radar Sensors, Natl.  Con( Proc. 
 W. G. Bath, L. 
 18. E. F. 
 CONCEPT  3 
 SIZE TARGET AND BY MULTIPATH ALSO CAUSE  SIGNIFICANT ANGLE 
 The weights are computed offline, by assuming an a priori known covariance matrix  M, and stored in a memory where a “menu” of weights is available to an operator or  an automatic decision system (pp. 277–283 of Farina34). Main Beam Cancellation (MBC) Systems. 
 I'liese will be introduced as needed.  Ariotlicr rriathcrnatical description of statistical phenomena is the probability distrihrrtiot~  Jirr~c.tir,r~ f'(u), dclined as tile probability tliat tile value x is less than some specified value  111 sorrie cases, tlie distribution function may be easier to obtain from an experimental set of  data tlian the derisity function. Tlie density function may be found from the distribution  futiction by dilferen tiatiori. 
 Chandrasekar, R. Meneghini, and I. Zawadzki, “Global and local precipitation measurements  by radar,” Chapter 9 in Radar in Atmospheric Science: A collection of essays in honor of David  Atlas , R. 
 J. I., arid 1-1. P. 
 D. Howard, “Precision tracking with monopulse radar,” Electronics , vol. 33,   pp. 
 TRACKING RADAR  9.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 Although the rms value of angle noise is essentially a constant for a given target and  aspect, the spectral distribution of this energy is dependent on radar frequency and the  random target motion. A typical spectrum shape is  N fB B f( )( )=+σπang2 2 2 2 (9.6) where N(f) = spectral noise power density, power/Hz  B = noise bandwidth, Hz  f = frequency, Hz The values of B are proportional to radar frequency and dependent upon air tur - bulence effects on target motion and target aspect. An example of a measured angle  scintillation spectrum is shown in Figure 9.23. 
 Clearly, the deviation between PolSAR TEC and ISR TEC is still within 1 TECU, which again validates the precision of PolSAR for TEC estimation. The small difference between “Poker Flat ISR” and “Poker Flat ISR (average)” indicates a stable ionosphere. For comparison, the TEC obtained from GNSS is 15.7 TECU, which is acceptable but not as precise as that of PolSAR. 
 SUITED TO APPLICA 
 52. Gunn, R., and Kinzer, G. D.: The Terminal Velocity of Fall for Water Droplets in Stag- nant Air, J. 
 510) dop pier band. split into r ranges— f,=; MA-m doppler system (See 511) f:rJ,<; I. SEC. 
 Sparking limits themaximum pulse length atwhich magnetrons can beoperated. Ofallthemodes ofoscillation possible inmagnetrons, only the~-mode isordinanl yused but allmagnetrons wil1sometimes oscillate inan unwanted mode, oralternate erratically between two modes. This tendency isresponsible forsome ofthe most troublesome problems in magnetron and pulser design. 
 This mode is optimized for low  cross section targets out to just beyond 75 km maximum range. The particular example  has overlapping range gates to minimize straddle loss and two PRFs to allow at least  one clear PRF near maximum range. The PRFs are 101.7 kHz and 101.3 kHz. 
 ARRAY RADAR DEMONSTRATOR v  0ROC    OF  )%%% 2ADAR #ONF  0HILADELPHIA 53!   !PRIL n    PP n  ! &ARINA  , 4IMMONERI  AND 2 4OSINI  h#ASCADING 3," AND  3,# DEVICES v  3IGNAL   0ROCESSING   %LSEVIER  VOL   NO   PP n    ! &ARINA AND , 4IMMONERI  h3YSTOLIC SCHEMES FOR *OINT 3,"  3,# AND ADAPTIVE PHASED 
 POLARIZED SIDELOBES FROM THE ARRAY  EXACERBATED BY THE PHASE REVERSAL OF THE CROSS 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter. 15.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 specular return , because its origin may be traced to pieces of the surface that provide  a reflection point for the incident wave.99,102 This expression is written for a gaussian  sea surface in the form  σ ψ ψ ψ0 22 4 2 2( ) (|| /)csc exp[ cot / ] = − R s s (15.17) where s is the rms surface slope and R is the flat-surface reflection coefficient for nor - mal incidence. 
 4.28 the zero-velocity filter (No. 1) threshold is determined by the output of  the clutter map. The thresholds for filters 3 through 7 are obtained from the mean level of the  signals in the 16 range cells centered around the range cell of interest. 
 Geophys., Res .,   vol. 100, no. C8, pp. 
 This table has been derived from IEEE Standard Letter Designations for Radar-Frequency Bands,  IEEE Std. 521-2002.  6. 
 However, progress was slow and by the end of the year the upgrade had to be made a standard modi ﬁcation, with the aircraft manufacturers responsible for installing the antennas and cables. At that stage, simple dipole antennas were still being used for homing and their performance was inadequate. It was recognised that greater homing ranges were needed and forward-looking high-gain Yagi arrays were developed. 
 V.: The Effective Number of Pulses Per Beamwidth for a Scanning Radar, Proc. IRE, vol. 41,  pp. 
 Spectral Noise in Doppler Radars.  The doppler frequency shift is widely used  to detect moving target echo signals in the presence of large clutter echoes. However,  if the radar transmitter generates noise or its pulse waveform has significant spec - tral energy at the doppler frequencies expected from moving targets, this unwanted  noise or spectra will degrade the detection of desired targets. 
 BAND FILTERS  OPERATING AT A SAMPLE RATE REDUCED BY A FACTOR  $  PROVIDING A COMPUTATIONALLY EFFICIENT  APPROACH TO PERFORMING THE &)2 FILTERING FOLLOWED BY DECIMATION IN A DIGITAL RECEIVER  2ATHER THAN COMPUTING ALL THE FILTER  OUTPUT SAMPLES AND ONLY USING EVERY  $TH SAMPLE   THE POLYPHASE APPROACH CALCULATES ONLY THOSE THAT ARE ACTUALLY USED &IGURE  AND %Q  DEFINE HOW THE FILTER WITH IMPULSE RESPONSE  HN   FOLLOWED WITH DECIMATION  BY FACTOR  $  IS IMPLEMENTED IN A POLYPHASE STRUCTURE 4HE INPUT SIGNAL  XN  IS DIVIDED  INTO $ PARALLEL PATHS BY THE hCOMMUTATOR v WHICH OUTPUTS SAMPLES IN TURN  ROTATING IN A  COUNTERCLOCKWISE DIRECTION  TO EACH OF THE &)2 FILTERS OPERATING AT THE REDUCED SAMPLE RATE 4HE OUTPUTS OF THE &)2 FILTERS ARE SUMMED TO PRODUCE THE OUTPUT SIGNAL  YM  4HIS  ARCHITECTURE IS BENEFICIAL AS IT PROVIDES AN APPROACH THAT CAN BE EASILY PARALLELIZED AT RATE & 8  $   PKN    HK   N$     K         x  $                   N         x  +     -ULTI 
 PULSE  CANCELER THAT HAS  
 16. H. T. 
 With such equipment inanairplane, roads will show uponthescope as intersecting lines ofdots due tothemoving vehicles. The drawback tothenoncoherent method isthat amoving target can bedetected only when there isground clutter atthe same range and azimuth asthetarget. Thus although themethod works well outtothe range where theclutter begins togetpatchy, beyond this range moving targets become lost inthe clear places. 
 These conclusions are only partly true. Inthe first place many ofthe unique capabilities ofradar, such asdirect range measurement ordetection ofvery remote objects despite cloud and dark- ness, often deserve more emphasis inradar design than does the ability ofthe settoproduce alifelike picture. Inthe second place, the pulse radar process issubject tocertain inherent limitations. 
 However, when  only a few pulses are available f~r'~rocessin~ there is probably little that can be done to  control the shape of the filter dharskteriitic. Thus, there is not much to be gained in trying to  shape the nonrecursive filtkr response for three- or four-pulse cancelers other than to use the  classical sin2 or sin3 response of the :' optimum " canceler.  The N-pulse nonrecursive delay-line canceler allows the designer N zeros for synthesizing  the frequency response. 
 The sliding spotlight mode controls the scanning velocity of beam footprint by steering the antenna, thus obtaining longer integration time than stripmap mode and larger scene than spotlight mode. Consequently, the sliding spotlight mode is a practical way for P-band high-resolution SAR system. However, little literature has been proposed to evaluate the ionospheric effect for P-band sliding spotlight SAR system. 
 FT DISH  BECAUSE OF THE LARGE MASS OF THE SYSTEM  .   42!#+).' 2!$!2   °£ 4HE RATIO WAS PUSHED TO A VERY MINIMUM OF ABOUT  TO OBTAIN SER VOSYSTEM BANDWIDTH  OF THE SPECIFIED  (Z ! SMALLER RADAR WITH A  
 Earth-Sci. Rev. 2014 ,138, 61–88. 
 "1-Ê* /", Ê "/" ÊÊ   Ê-  Ê " * 
 The designers, however, adopted asageneral policy the improvement orextension beyond current practice ofequipment characteristics that determined theaccuracy and speed ofdata presenta- tion and use. Care was also taken inthe design topermit still greater extension ofthese facilities bysimple changes oradditions. Beam Shape in Elevation.—A large air-surveillance set must be located onthe ground orbeelevated atmost byalow tower toavoid interference by!ocal obstruct ion. 
 14.6 that would generate afrequency above resonance, the machine speed would continue toincrease, being limited only byfriction and windage losses. CentrifWal Control.—The most recent method ofspeed regulation tobeused onaircraft inverters isacarbon-pile governor asused by theHoltzer-Cabot Electric Company. Itisshown inFig. 
 The following error model exclusively corrects the systematic errors,  while the statistical errors can normally be reduced through integration.  The error model co n- siders the following contributions:   Error due to the environment (e.g. non -ideal anechoic measurement chamber),   Error due to the coupling of th e transmitting into the receiving channel,   Errors, which have been caused due to the coupling between the orthogonal receiving  channels of the polarimetric measurement system (antenna as well as cables and  electronics),   Errors, which arise due to the coupl ing of the transmitting channel   Errors, which arise along the transmission path. 
 The Rebecca [ 7]b a n do n2 1 4 –234 Mc/s, with ﬁve channels, was chosen, although the Lucero Mk. II design also retained 176 Mc/s foruse when IFF was required. The essential components of a Lucero installation are shown in ﬁgure 6.1[3]. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar.  TRACKING RADAR  9.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 rate of rotation. 
 . Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 109     11.7 RCS of Complex Objects   For objects such as airplanes and ships (understood under the term “complex objects”), n u- merous, widespread from one another scattering centres contribute to the Radar scattering  cross- section. Therefore, the RCS pattern can become very irregular. 
 -1, 
 15.1  15.1 Introduction to MT I Radar  .......................................  15.1  Moving-Target Indicator (MTI) Block  Diagram  ..........................................................  15.3  Moving-Target Detector (MTD) Block  Diagram  .......................................................... 
 Automatic Target Detection in Synthetic Aperture Radar Imagery: A State-of-the-Art Review. IEEE Access 2016 ,4, 6014–6058. [ CrossRef ] 3. 
 STATE TRANSMIT DEVICES  PERMITS THE DEVICE HEATING AND COOLING TO BE IDENTICAL FROM PULSE TO PULSE 3OMETIMES CONSTANT DUTY CYCLE OPERATION IS NOT POSSIBLE  BUT THERE ARE VARIOUS TECHNIQUES THAT CAN BE USED TO APPROACH THIS DESIRED CONDITION #ONSIDER AN -4$ WAVEFORM WHERE A #0) CONSISTING OF  N PULSES IS TRANSMIT 
 NELS EG  DEGREES OF MATCHING  4HERE IS SOME TRADE 
 A  separate a posteriori probability is computed for each hypothesis. That hypothesis which  results in the largest a posteriori probability is selected as the most likely to explain the event.  This method has been applied by Woodward and Davies to the reception of signals in  It is based upon the application of Bayes' rule for the probability of causes.29 The  joint probability of two events x and y is  where p(x) and p(y) = probabilities of events x and y, respectively  p(y 1 x) = conditional probability that event y will occur, given that event x has  occurred  p(~ 11.) - ronditir>tinl nrohnhilitv nf  veti it u eiven flint I. 
 Thechirpwaveform i'smore vulnerable torepeater jamming thanisthephase-coded pulse.Thechirpwaveform ismore likelytobeusedwhenawidebandwidth, orverynarrowcompressed pulse,isrequired. The phase-coded pulseismorelikelytobeusedwhenjamming orEMCisaproblem, orwhen long-duration waveforms aredesired. Generally, theimplementation ofthechirppulse­ compression hasbeenlesscomplex thanthatofthephase-coded pulse. 
    
 J. W. Ryde and D. 
 BAND CHAN 
 PROCESSING FUNCTION  THE CONCEPT IS EXPLAINED HERE FOR COM 
 DOPPLER CELLS  WHEN THE GUARD CHANNEL RETURN IS GREATER THAN THAT OF THE MAIN CHANNEL  THE DETECTION IS REJECTED BLANKED  )F THE MAIN CHANNEL RETURN IS HIGHER  THE DETECTION IS PASSED ON ! BLOCK DIAGRAM OF A GUARD CHANNEL MECHANIZATION IS SHOWN IN &IGURE  !FTER  THE #&!2 WHICH IDEALLY WOULD BE IDENTICAL IN BOTH CHANNELS   THERE ARE THREE THRESH 
 Wu, J.; Zhu, Y.; Wang, Z.; Song, Z.; Liu, X.; Wang, W.; Zhang, Z.; Yu, Y.; Xu, Z.; Zhang, T.; et al. A novel ship classiﬁcation approach for high resolution SAR images based on the BDA-KELM classiﬁcation model. Int. 
 One rotary  joint permits motion in azimuth; the other, in elevation.  Target axis  Rodar  Figure 5.2 Conical-scan tracking. 156 INTRODUCTION TO RADAR SYSTEMS  Transmitter  Receiver To rotary joint  on antenna ~---1 Duple~er with --- AGC Second deteclor --;-Ronge gale ,.. 
 The sum  signal provides the range measurement and is also used as a reference to extract the sign of the  error signal. Signals received from the sum and the difference patterns are amplified separately  and combined in a phase-sensitive detector to produce the error-signal characteristic shown in  Fig. 5.7d. 
 Barter, K. L. Beach, E. 
 tion ofthemicrowave circuit, near theT-junction ofthe receiving branch and the magnetron-antenna line, where theTR and ATR switches arelocated. The great disparity intransmitted and received powers immediately suggests that aspark gap orgas-discharge tube can beconnected inth-e circuit insuch away astoperform the necessary switching operations. These gas-discharge tubes arereferred toasTR orATR tubes. 
 3.3). Wecan find thecross section foracorner byconsidering itequivalent toa flatreflecting plate whose area istheeffective area ofthecorner for triple reflection. Equation (7)gives, forarea .-landwavelengthk, the cross section 4TA ‘ ‘= A’” The maximum area fortriple reflection ~vill bethat afforded bythecorner tlhen itis~-ieived along itsaxis ofsymmetry. 
 USE  SHIPBORNE PHASED ARRAY RADAR TECHNOLOGY AND TACTICAL ENVIRONMENTAL SENSING v IN  0ROC )%%%  .ATIONAL 2ADAR #ONF  !TLANTA    PP n  $ % &ORSYTH  + * +IMPEL  $ 3 :RNIC  3 3ANDGATHE  2 &EREK  * & (EIMMER  4 -C.ELLIS  * %  #RAIN  ! - 3HAPIRO  * $ "ELVILLE  AND 7 "ENNER  h4HE NATIONAL WEATHER RADAR TESTBED PHASED  ARRAY  v PRESENTED AT TH )NT #ONF ON )NTERACT )NFO 0ROC 3YS ))03   !-3  /RLANDO    2 , 4ROTTER  h$ESIGN CONSIDERATIONS FOR THE ./!! AIRBORNE METEOROLOGICAL RADAR AND DATA  SYSTEM v IN TH #ONF ON 2ADAR -ETEOROL  !-3  !TLANTA    PP n  ( " "LUESTEIN AND 2 - 7AKIMOTO  h-OBILE RADAR OBSERVAT ION OF SEVERE CONVECTIVE STORMS v  #HAPTER  IN  2ADAR IN !TMOSPHERIC 3CIENCE ! COLLECTION OF ESSAYS IN HONOR OF $AVID !TLAS   2  7AKIMOTO AND 2 3RIVASTAVA EDS   -ETEOROLOGICAL -ONOGRAPH  6OL   "OSTON !-3    PP n  0 ( (ILDEBRAND  # ! 7ALTHER  # , &RUSH  * 4ESTUD  AND & "AUDIN  h4HE %,$/2! !342!)! AIRBORNE DOPPLER WEATHER RADAR GOALS  DESIGN AND FIRST FIELD TEST v  0ROC )%%%  VOL     PP n    ' - (EYMSFIELD ET AL  h4HE  %$/0 RADAR SYSTEM ON THE HIG H ALTITUDE .!3! %2 
 58. Bacon. G. 
        .   05,3% $/00,%2 2!$!2   {°Óx INSTANTANEOUS DYNAMIC RANGE IS PREFERABLE )F SATURATIONS OCCUR IN A RANGE GATE DURING  AN INTEGRATION PERIOD  AN OPTION IN A MULTIPLE 
 28. J. M. 
 R. A.: "Computer Control of Modern Radars," Privately published by RCA Inc., 1973.  122. 
 The usual design J procedure is to compute the ambiguity diagram for the more common waveforms and to  observe its behavior. Because of the limitations of synthesis, the ambiguity diagram has been  more a measure of the suitability of a selected waveform than a means of finding the optimum  waveform.  Single pulse of sine wave. 
 The Method ofPre-time-base Resolution.—In certain cases itisdesirable totransmit the scanner data interms ofslowly varying sine and cosine voltages derived from asine-cosine potentiometer, orby themodulated-carrier technique used intheB-scope ofSec. 13.14. These are used aspotential sources forsawtooth generators, asindicated in Fig. 
 n°{{  2!$!2 (!.$"//+   7 * #APUTI  h3WEPT 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar.  PULSE DOPPLER RADAR  4.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 The converse of a low-PRF radar is a high-PRF radar that can measure doppler  unambiguously over the span of radial velocities of interest, but is usually highly  ambiguous in range. 
 Technically, the turbulent ionosphere can be considered to be a very thin phase screen at an equivalent altitude and the radar beam scans over the phase screen within the integration time. Hsatis the orbit height of radar platform and Hionois the equivalent ionospheric height at 350 km. IPrepresents the ionospheric penetration point (IPP) and Xionois the IPL within acquisition time. 
 Any corrections for a phase taper . COLUMN PHASE COMMANDS FIG. 7.11 Microwave addition of orthogonal phasing commands by means of a series feed. 
 ££    P  . 
 HORIZON RADAR  6(& AND 5(& AIRCRAFT SURVEILLANCE RADARS  AND SATELLITE SURVEILLANCE RADARS 'RID 
 1708–1718, 1957. 38. P. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12   blind folio 12.44 ch12.indd   44 12/17/07   2:32:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The flip-flop isfired bythe modulator trigger, sothat video signals arepassed until shortly before the next cycle, atwhich time the flip-flop opens the switch forpulses until themodulator pulse occurs again. Atthe receiving station, signals from the receiver pass toaswitch which isopen when apulse code isexpected. Following this switch isa decoder similar tothat ofFig. 
 Similar, but converse, conditions obtain forfre- quencies higher than band center. Figure 11.4 shows how abroadband stub can beused tomake anelbow. There isanadded complication because the sharp elbow introduces areactance which must becompen- sated forintheconstruction ofthestub. 
 FILTERING  PROBLEM  IE  A CASCADE OF FILTERS IN WHICH THE INPUT SAMPLING RATE IS HIGHER THAN THE OUTPUT SAMPLING RATE  AS SHOWN IN &IGURE   WHICH REQUIRES VERY CAREFUL ATTENTION TO RANGE AND AZIMUTH FILTER SIDELOBES 4YPICALLY  THE SPACING OF INDIVIDUAL PULSES ON THE  GROUND IS CHOSEN TO BE MUCH CLOSER THAN THE DESIRED ULTIMATE RESOLUTION 4HIS ALLOWS  LINEAR RANGE CLOSURE AND PHASE CORRECTION SINCE EACH POINT ON THE SURFACE MOVES A SIGNIFICANT FRACTION OF A RANGE CELL PULSE TO PULSE  n    4HE INPUT SIGNAL  POINT  ! IN &IGURE   IS SHOWN AS A SPECTRUM AT !  FOLDED ABOUT THE 02& ON THE LEFT IN &IGURE  3UBSEQUENTLY  PRESUMMATION IS APPLIED  WHICH FORMS AN UNFOCUSSED SYNTHETIC BEAM  OR FILTER INSIDE THE MAIN 
 These curves were calculated assuming a (sin U)/U antenna pattern  terminated at the first nulls.  The no-feedback curves shown in Figure 2.37 are almost indistinguishable from  the theoretical curves derived for a gaussian pattern shown in Figure 2.19. (One of the  curves showing the effect of feedback on the triple canceler is not straight because two  of the three zeros are not at the origin but have been moved along the unit circle the  optimum amount for 14 hits per beamwidth. 
 OTHER RADAR TOPICS 547  arc sllor t co~ril~atctl to tlic titlie tlillc.~c.~icc r,, . I;OI a I1;1t c;11 tli. tlic Iiciglil of 1111: 1:11gct is  (.l<t/) It, = 211,  wlicrc (. 
 especially if garnets  are used. This type of latching phase shifter is also called a twin-slah toroiilal plwse -'l,ifier since  the major action is due to the two vertical branches of the toroids. The function of the  horizontal branches is to complete the magnetic circuit. 
 Such polarization diversity adds considerable complexity, requiring two feed systems or switches at the radiating element level. Circular Polarization. From the point of view of the antenna designer, cir- cular polarization is possible, though difficulties may be encountered in matching for large scan angles. 
 15.2 CLUTTERFILTERRESPONSETOMOVING TARGETS The response of an MTI system to a moving target varies as a function of the target's radial velocity. For the MTI system described above, the response, nor- malized for unity noise power gain, is shown in Fig. 15.8. 
 %23 
 A false-alarm probability of 0.05 is  usually high for most radar applications. Radar false-alarm probabilities are rarely greater  than Low values of false-alarm probability with the Ideal Observer require extremely  large values of detection probabilities. For example, a false-alarm probability of 10- corre-  sponds to a detection probability of 0.99998. 
 7, pp. 104-106, Apr. 4, 1974. 
 However, by using appropriate coherent process - ing, an aperture of modest size may be moved (e.g., by an aircraft or spacecraft—referred  to as the platform ) along a path in space—a synthetic aperture —and may achieve cross - range resolution comparable to what would, in principle, be achieved by a real aperture  with a length equal to the path length (synthetic aperture) LSA:  δλ λ cr SA≈ ≈R L2 2 ∆q  (synthetic aperture) (17.2) where ∆q is the synthetic aperture angle, i.e., the angle subtended by the synthetic  aperture as seen from the target area. The additional factor of two in the denominator  (compared with Eq. 17.1) occurs because of the SAR processing and will be discussed. 
 Its accuracy will  therefore riot be affected by changes in amplitude with time.  TRACKING RADAR167 difficult toilluminate asinglerellector withmorethanonefeedandproduce independent antenna patterns whichilluminate thesamevolumeinspace. Although tracking radarsbaseduponthephase-comparison monopulse principle have heenbuiltandoperated, thistechnique hasnotbeenaswidelyusedassomeoftheother angle-tracking methods. 
 Theenvelope hasa fluctuating appearance causedbytherandomnatureofnoise.Ifalargesignalispresentsuch asatAinFig.2.1,itisgreaterthanthesurrounding noisepeaksandcanberecognized onthe basisofitsamplitude. Thus,ifthethreshold levelweresetsufficiently high,theenvelope would notgenerally exceed.thethreshold ifnoisealonewerepresent,butwouldexceeditifastrong signalwerepresent.Uthe signalweresmall,however, itwouldbemoredifficulttorecognize its presence. Thethreshold levelmust.belowifweaksignalsaretobedetected, butitcannotbeso lowthatnoisepeakscrossthethreshold andgiveafalseindication ofthepresence oftargets. 
 Author Contributions: C.W., W.G. and H.Z. initiated the research. 
 L. T .. and J. 
 PULSE CHANGE IN AMPLITUDE 4HIS  LIMITATION APPLIES EVEN THOUGH THE SYSTEM USES LIMITING BEFORE THE CANCELER BECAUSE  THERE IS ALWAYS MUCH CLUTTER PRESENT THAT DOES NOT REACH THE LIMIT LEVEL 7ITH MOST TRANSMITTERS  HOWEVER  THE AMPLITUDE JITTER IS INSIGNIFICANT AFTER THE FREQUENCY 
 IEEE J. Sel. T op. 
 PLING WHICH CAUSES THE PEAK OF THE COMPRESSED PULSE TO SHIFT IN TIME BY AN AMOUNT  PROPORTIONAL TO THE DOPPLER FREQUENCY 4HE PEAK OCCURS EARLIER IN TIME AT  T   nFD4" FOR  A POSITIVE ,&- SLOPE  COMPARED TO PEAK RESPONSE FOR A STATIONARY TARGET 4HE PEAK OF THE AMBIGUITY FUNCTION IS SHIFTED TO S     F D4" FOR A POSITIVE ,&- SLOPE 4IME $ELAY AND 2ANGE 2ESOLUTION 7IDTHS  4HE TIME 
 Sensors 2019 ,19, 3073 2.3. Improved Deformation Model Considering Rheological Parameters When horizontal movement is ignored, the vertical settlement can be calculated according to the formula SLOS=Svcosθ. Combined with Equations (3)–(5), the deformation components related to rheology along the line-of-sight direction can be expressed as SLOS _rhe=Hcosθσ c E(t2−t1)−ηcosθHσc E2⎭parenleftbigg e−E ηt1−e−E ηt2⎭parenrightbigg . 
 For  example if D,,/D = 0.122. the gain would be lowered by about 0.3 dB and a -20 dB sidelobe  would he increased to about -l 8 dB.  Aperture blocking may be reduced by decreasing the size of the subreflector. 
 Signals from thereceiver aredlfferentiated bythegrid circuit ofamplifier VICsothat blocks ofsignals arenotpassed. Iftheincoming pulses arelarge enough, the tube can bebiased past cutoff inorder to exclude signals atlower levels (as, forexample, when amplitude istobe used asabasis ofdiscrimination between pulses and video signals). Weak interference can also beexcluded inthis way. 
 Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar.  PULSE DOPPLER RADAR  4.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 FIGURE 4.13  Single-channel sidelobe blanker using postdetection STC or RCS thresholding to remove sidelobe discretes.Unambiguous Detections Out Matched Filter, Weighting & FFTSquare Law DetectorCFARAmbiguous Detections PRF #1 Ambiguous Detections PRF #2“A” Range Correlator  Range Unfolding & M of N Correlation (out to STC Onset Range)“C” Range Correlator  Range Unfolding & M of N Correlation of remaining detects “B” Range Correlator  Range Unfolding & M of N Correlation with  STC (or RCS) threshold (out to STC Onset Range) Ambiguous Detections PRF N STC function or RCS ThresholdMatched Filter, Weighting & FFTSquare Law DetectorCFAR Matched Filter, Weighting & FFTSquare Law DetectorCFAR“A • B” = if M of N in “A” & NOT M of N in “B”Blanking Logic: if “A • B”  blank detects (and their unfolded ranges) ch04.indd   23 12/20/07   4:52:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 7 .34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 tracking errors due to radar measurement noise. 
 /,9 3EVERAL SYNTHETIC 
 measured ahoutthelineofsight.hetwcen thevertical planethrough thelineofsightandthe planeperpcndicular tothedeckthrough l.hclineofsight. AIltmll9 drhl'S.llh.t 11Mechanical tracking radarsandnodding-beam heightfindersrequire variahle drivcpower.Thcchoicchashccnhctwcen electrical andhydraulic systems. Electrical drivcsarcIheWanlLconard typeorthyrislor hridgesdrivingdcmotors. 
 BAND )-$ ARISES FROM NONLINEAR MIXING  OF TWO OR MORE  STRONG INTERFERERS SUCH AS BROADCAST STATIONS  WHERE THE POWERFUL SIGNALS ENTER THE FRONT END OF THE RECEIVING SYSTEM AND GENERATE )-$ PRODUCTS WITHIN THE RADAR SIGNAL BANDWIDTH BEFORE THEY  THE ORIGINAL INTERFERERS  ARE REJECTED BY SELEC 
 The angle-error-signal voltage is shown in Fig. 5.6 as a function of Or, the  angle between the axis of rotation and the direction to the target.12 The squint angle 09 is the . 0. 
 COMPENSATED DIRECTIONS OF SCAN FOR A CORRESPONDING INCREASE IN BANDWIDTH 4HE PHASING OF THE ANTENNA HAS TO INCLUDE A CORRECTION FOR THE SPHERICAL PHASE FRONT  4HIS CAN BE SEEN &IGURE A  TO AMOUNT TO    P LP LFRFR FR F 
 A software model  has been developed and verified in several flight trials in the case of a ground-based  DRFM jammer.  ECCM techniques for SAR can be divided into (i) antenna-based techniques (low  sidelobes, adaptive arrays) and (ii) transmitter/receiver/processing–based techniques  (frequency agility, pulse coding). • Low sidelobes . 
 34. Yang, Z.; Li, Z.; Zhu, J.; Yi, H.; Hu, J.; Feng, G. Deriving dynamic subsidence of coal mining areas using InSAR and logistic model. 
 III as the reference, the noise-limited performances of ASV Mk. VI and ASV Mk. VII would have been 10.5 dB and 8 dB greater, respectively. 
 Thus, by transmitting a  number of frequencies and using the angle error corresponding to that frequency with the  largest signal, it is possible to eliminate the large angle ~rrors associated with glint. 39.4° Those  returns of low amplitude and, hence, of high error, are excluded in this technique. Instead or  selecting only the largest signal for processing, the indicated position of the target at each  frequency can be weighted according to the amplitude of the return.40 Only a small number of  frequencies is needed to reduce substantially the glint error. 
 King: Measurement oft he Radar Cross-section of a Man. !'rue.  IRE. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.476x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 Series Feeds.  Figure 13.31 shows several types of series feeds. 
 Nathanson, F. E.: "Radar Design Principles," McGraw-Hill Book Company, New York, 1969,  chap. 4. 
 and J. Frank: Array Antennas, chap. I l of Radar Ha11dbook, M. 
 2 1. pp. 369-373. 
 &)'52%    )MPULSE RESPONSE OF  
 Reflection.  In any estimation of received signal level, it is necessary to consider  the coefficients of reflection and transmission, as the wave passes through the dielectric  to the target and Snell’s Laws describe the associated angles of incidence, reflection,  transmission, and refraction. Where lossy materials are involved, complex angles of  refraction may occur unlike the simple classical case, and polarization and the Stoke’s  matrix may also be required for oriented high-aspect ratio features like pipes, wires,  and fractures. 
 New York: McGraw-Hill, Inc., 1991,   pp. 281–282. 47. 
 An alternative version of this detec - tor is to put the batch amplitudes through a moving-window detector . The batch processor, like the binary integrator, is easily implemented, ignores inter - ference spikes, and works extremely well when the noise has a non-Rayleigh density.  Furthermore, the batch processor requires less storage, detects better, and estimates  FIGURE 7.10  Comparison of binary integrator ( M-out-of- N) with  other integration methods ( Pfa = 10−10; PD = 0.90) ( after M. 
 The upper scale of the  abscissa gives the one-half-wavelength dimension of the frequency given on the  lower scale. The curve marked 90 ° is the RCS of the oblong-shaped conducting body  of 11 m length and 1 m thickness; again, the target long dimension is aligned with  the electric field. The maximum RCS coincides with the nominal half-wavelength  dimension or with the first resonance. 
 2%. Kcrr. I). 
 115.Goldstein. G.B.:False-Alarm Regulation inLog-Normal andWeibulJ Clutter,IEEETrailS.,vol. AES-9,pp1\4-92,January. 
 The same  10 mm 1 mm O 1 mm 10 1 µm  100~~~~1-rr---r-.-rT,r--,.---,-~1,--,---.-,...,...,..,.,-~--,--,-1--,--.-rrTTr--~~..-,.-,-,--,-,-~~-,,-----r-l ....,-.,-.-,·TT"\  10 · 35 GHz  Clear  atmosphere N  0 g  0  <.D N  94140 220i3  I  I  I LO x ~  I!) = = S:J 1111  I  I  I  I  I Clear almoS{i\ere attenuation  greater than 30 dB/km in ..\  this region 1  Rain Smm/hr  Kain O 25 mm I hr V1s1ble  region  t--... 1  QLL--'L--'-LL.J...l...w..L.L'~~_,.L_..LJ.-l-LJ....LL~--'---''--'--1-L...L.L~:,-_L..--.L .... .J..-.,__._~~~~-·"---'..--~~~~.Ob  10 100 1.000 1  Frequency -GHz  Figure 14.15 One-way attenuation of electromagnetic energy propagating in the clear atmosphere87  (oxygen and water vapor at 7.5 g/m3, 1 atmosphere pressure, and absolute temperature equal 293 K),  rain88 at 293 K, the total attenuation of fog with a visibility or 300 m and at 293 K (includes attenuation  through a clear standard atmosphere), and fair weather cumulus cloud with a mode radius of 4 ,,m, a  water content of 0.063 g/mJ, and a drop density of i00/cm3.~9•90 . 
 Cherry, “Investigation of microwave scattering by tall buildings,” Proc.  IEE, vol. 120, pp. 
 Oneofthemajorchanges isinthetreatment ofMTI(moving targetindication) radar (Chap.4).MostofthebasicMTIconcepts thathavebeenaddedwereknownatthetimeofthe firstedition, butlheyhadnotappeared intheopenliterature norweretheywidelyusedin practice. Inclusion inthefirsteditionwouldhave'been largelyacademic sincetheanalog delay-line technology available atthattimedidnotmakeitpractical tobuildthesophisticated signalprocessors thatweretheoretically possible. However, subsequent advances indigital lechnology, originally developed forapplications otherthanradar,haveallowedthepractical implementation ofthemultiple delay-line cancelers andmultiple pulse-repetition-frequency MTIradarsindicated bythebasicMTItheory. 
 In Table 9.1 the color emitted by the screen during both fluorescence (short duration) and  phosphorescence (long duration) is given. In general terms, fluorescence may be thought of as  luminescence which ceases almost immediately upon removal of the excitation, whereas in  phosphorescence the luminescence persists. Cascaded screens produce different colors under  fluorescence or phosphorescence. 
 AIR OBSERVATION FOR A COMPLETE DESCRIPTION OF THE PROPA 
 The output of the  delay line is a signal of freque11cy.f~ with a phase shift 4 = 2nfc r. This phase-shifted signal and  the output of the first ri~ixer are then heterodyned in the second mixer. If the sum frequency is  selected froin the first tiiixer, the difference frequency is selected from the second mixer. 
 L. BOLtz  HOW RADAR WORKS  BY  KENNETH ULLYETT  F.R.Met.S. A.M.S.E. 
 Thus, there is a demand  for two ingredients: (i) information about the environment and (ii) a mechanism, or at  least a strategy, for using that information to control the radar parameters. At the very minimum, HF skywave radars must maintain a real-time awareness of  propagation conditions as a function of frequency, range, and bearing (azimuth), as  well as a detailed knowledge of spectrum occupancy. This is usually achieved by pro - viding auxiliary facilities, including some or all of the following: (i) Conventional ion - ospheric sounders (vertical and oblique incidence), which determine the ionospheric  electron density profile by measuring the time of flight of reflected radiowaves over  a range of frequencies; this electron density profile information is assimilated into  ch20.indd   54 12/20/07   1:16:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 As an example, one transmitter and har- monic filter combination might have a 5- to 9-MHz passband and a stopband for 10 Mhz and higher frequencies; a second combination might pass up to 17 MHz and reject 18 Mhz and higher, and the design would continue in this manner to the highest frequency of operation. 24.4 ANTENNAS A single antenna can be duplexed and used for both transmit and receive. The Naval Research Laboratory (NRL) magnetic-drum recording equipment (MADRE) antenna is an example.1 This 100-m-wide by 40-m-high aperture provided sufficient gain and angular resolution for aircraft tracking in the up- per part of the HF band: the frequencies used in daytime. 
 25. J. W. 
 17.6 The Phase-shift Method 17.7 Methods ofRelaying Sine and Cosine 17.8 Pulse Method forRelaying Sine and Cosine. 17.9 Comparison ofSynchronization Methods....682 6S3 685 .,. 689 695 701 705 711. 
 34. D. C. 
  .KM OR  
 Archer: A Toroidal Microwave Reflector, I RE N,itl. Conr. Record, vol. 
 Óä°{ä  2!$!2 (!.$"//+  /N THESE OCCASIONS  THE FLUX OF METEORS CAN BE SO HIGH THAT THEY CAN CAUSE SERIOUS  OBSCURATION OF TARGET ECHOES !S RADARS BECOME MORE SENSITIVE  THEY REGISTER SMALLER AND SMALLER METEORS  WHICH ARE FAR MORE ABUNDANT  SO AT TIMES  THE FLUX OF COUNTLESS SMALL METEOR TRAILS SETS THE EFFECTIVE DETECTION THRESHOLD -ETEOR ECHO SUPPRESSION CAN BE ATTEMPTED IN THE SPATIAL DOMAIN IF THE RECEIVING  ARRAY HAS VERTICAL DIRECTIVITY  BUT FOR MOST RADARS  THE ONLY OPTION IS REJECTION BY SIGNAL PROCESSING  EXPLOITING THE TRANSIENT NATURE OF THE ECHOES TO DETECT AND CENSOR THEM IN THE TIME DOMAIN %CHOES FROM THE AURORAE SIMILARLY INVOLVE TRANSIENT SCATTERING PROCESSES THAT APPEAR  IN THE RADAR DATA AS HIGHLY DOPPLER 
 Filter objective is to  minimize lag plus c standard  deviations.51,52Q submatrix not  applicable. Instead,  assume constant  parabolic motion 1 22at.β αα = − − −2 2 4 1( ) and γσtrack=a T cm2 4 2 2 .Vary a to increase/   decrease gains  and obtain desired  performance using  equations in Table 7.3.Filter minimizes error for  a worst-case deterministic  maneuver vice a random one.TABLE 7.4  Comparison of Methods of Tuning Kalman Filter for Practic al Radar Tracking Problems ( Continued ) ch07.indd   32 12/17/07   2:14:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Revisit times might range from one to  12 seconds, depending on the application. Track-while-scan (TWS) . Usually a radar that provides surveillance over a nar - row region of angle in one or two dimensions, so as to provide at a rapid  update rate location information on all targets within a limited angular region  of observation. 
 In general, the relaxation time (which  may be expressed as a relaxation frequency) depends on activation energy, the natural  frequency of oscillation of the polarized particles, and on temperature. Relaxation  frequencies vary widely between different materials. For example, maximum absorption occurs at very low frequencies in ice (103 Hz),  whereas it takes place in the microwave region in water (106 Hz–1010 Hz); thus, the  effects of this phenomenon can have a direct bearing upon the dielectric properties  of materials at the frequencies employed by GPRs, especially if moisture is present  within a material. 
     PP n     $ "ARRICK AND 1 0EAKE   h! REVIEW OF SCATTERING FROM SURFA CES WITH DIFFERENT ROUGHNESS SCALES v  2ADIO 3CI  VOL   PP n     $ !TLAS  2 # "EAL  2 ! "ROWN  0 $E -EY  2 + -OORE  # ' 2APLEY  AND # 4 3WIFT   h0ROBLEMS AND FUTURE DIRECTIONS IN REMOTE SENSING OF THE OCEANS AND TROPOSPHERE A WORKSHOP  REPORT v * 'EOPHYS 2ES  VOL #   PP n    $ (OLIDAY  ' 3T 
 561, May, 1971.  60. Hansen, V. 
 L <l.> 0.0.oo Figure3.1Doppler frequency [Eq.(3.2b)Jasafunction ofradarfrequency andtargetrelativevelocity.. important early applications of the CW radar principle were the proxim~ty (VT) ftire and the  FM-CW altimeter. The CW proximity fuze was first employed in artillery projectiles during  World War 11 and greatly enhanced the effectiveness of both field and antlaircraft arttllery  Tile first practical model of the FM-CW altimeter was developed by the Wt'slern Electric  Company in 1938, although the principle of altitude determination using radio-wave  reflections was known ten years earlier, in 1928.'  The CW radar is of interest not only because of its many applications, hut its sttidy also  serves as a means for better understanding the nature and use of the doppler inforrnatlon  contained in the echo signal, whether in a CW or a pulse radar (MTl) application. 
 For example. the  signal-to-noise ratio will be within 0.5 dB of optimum for 1?2 ranging over a value of 0.44 !r for a  nor~fluctuating target or a Swerling case I, and 0.34 n for a Swerling case 2.59  The quantization of signals into but two levels (zero or one) in the binary moving-window  detector results in a loss of about 1.5 to 2 dB in signal-to-noise ratio as compared to the ideal  post-detection integrat~r.~~ 55.5 ' When the artlplitude is quantized into more than two levels,  the loss is less. For example, quantization into four levels (2 bits), reduces the loss to about  or~c-tllirti (Ilit t experienced ir~ t wo-level, or binary, quantization (1 bit).60  A corollary advantage of the binary rnoving-window detector is that it is less sensitive to  the effects of a single large interference pulse that might exist along with the target echo pulses. 
 Nathanson, F. E.: "Radar Design Principles," McGraw-Hill Book Company, New York, 1969,  chap. 5. 
 Metal members  are not only superior in electrical performance to the equivalent dielectric members but metal  space-frame radomes are generally cheaper and easier to fabricate, transport, and assemble,  and can be used for larger diameter configurations.  Aluminum structural members, which might be larger than steel of equivalent strength,  are of light weight, noncorrosive, and require no maintenance. The load-bearing framework is  covered with low-loss fiberglass-reinforced plastic panels. 
 72-75, IEEE Publication 74 CHO 883-1 AES.  45. Barton, D. 
 SQUARED 
 , N. The frequency J.,  which is the rate at which the far field is sampled, must be greater than the total signal  bandwidth if the modu_lation envelope of the radar pulses is to be preserved. The outputs from  the elements must be limited to a bandwidth B before adding them all together, if noise overlap  is to be avoided. 
  
 FIQ.14.7.—KS-15O55 electronic voltage regulator designed byBellTelephone Laboratories. Aconventional amplifier isused which must have sufficient gain to provide the required over-all sensitivity. Stable operation ofthe combination ofvoltage-sensitive element, amplifier, output stage, and alternator demands that the usual conditions forstability ofaservo system befulfilled. 
 Main-beam ef- fects would be included in the platform-motion improvement factor. The constant K is the noise normalization factor for the MTI filter. (K — 2 for single delay and 6 for double delay.) G4CB) is the two-way power of the antenna in the plane of the ground surface. 
 Struts are used to support the feed, and for center-fed reflec - tors, typically form a tripod, as shown in Figure 12.12. Strut scattering is a complex  phenomena that depends on strut size, strut geometry, field polarization, and other fac - tors. However, in general, strut interference scattering will lie within a conical region  about the strut axis. 
 l2 It is also possible to generate a palr of  stereo images on a single pass using two vertical fan beams at different azimuth angles, or one  fan beam and a conical beam.13 The stereo processing of SAR images has been successfi~lly  used for mineral exploration.  At short ranges it is possible to use conventional noncoherent sidelooking radar with a  large antenna aperture and pulse compression to obtain high-resolution terrain imaging. The  images obtained with conventional noncoherent radar are generally dift'erent than those of  coherent SAR in that they are less speckled. 
 Smith. E. K .. 
 80, pp. 522-545, October, 1954.  72. 
 The man attheright hascommunications lines tha~ connect him with the radio truck associated with the SCR-584 station, ~vith aradio direction-finding station, and with theFDP under ~vhich theSCR-584 is operating. The 180° plotting table used with the SCR-584 was admittedly a FIG. 716.-Interior ofSCR-5S4 modified forclose control, showing lSOO plotting board. 
         &)'52%   3IMULATION OF ! 
 29. V . G. 
 SON AMPLITUDE AND PHASE ADJUSTMENTS ARE APPLIED TO ANTENNA ELEMENT AND TIME DIS 
 3.The values ofthe sine and the cosine ofthe scan angle can be transmitted inany ofseveral ways (Sec. 17.7). Transmission of sine and cosine isalso asingle-valued method. 
 In order to get as much information as possible in the scene, the difference in the direction of the three beams is at least 20◦. 10. Sensors 2019 ,19, 1701 'LJLWDO75 PRGXOHĊ'LJLWDO75 PRGXOH 3KDVHVKLIWHU 6XP &RQWURO SURFHVVRUĊ'LJLWDOPXOWL EHDPIRUPLQJ 6LJQDORXWSXWRI WKHILUVWEHDP 6LJQDO SURFHVVRU'LJLWDO75 PRGXOH 3KDVHVKLIWHU 3KDVHVKLIWHU 6LJQDORXWSXWRI WKHVHFRQGEHDP6LJQDORXWSXWRI WKHWKLUGEHDP Figure 2. 
 .ATURAL  2ESOURCES #ONSERVATION 3ERVICE 53$! 
 Figure 11b is the image based on the basic MAM method. The azimuth center of the scene is well-focused, but there is still obvious defocus at the azimuth edges, indicating that the estimation results of the Doppler parameters by the basic MAM method are the averages of the real Doppler parameters of the whole scene, which are close to the real ones of the central scene. Figure 11c,d shows the images based on the IMAM method and the EMAM method, respectively. 
 1TheIspacefeeddistributes theenergytoalensarrayora. IIIF I:I I (.IRONI('AI I Y SIFFRI:I> I'lIASFI> ARRAY ANTFNNA IN RADAR 307  f;ig~rrc. 8.21 Planar array wit11 pl~nse-sllift volu~netric scan in two angular coordinates. 
 The radar cross section of an aircraft can also be obtained by c~mputation.'~ The target is  broken up into a number of simple geometrical shapes, the contribution of each (taking  THERADAR EQUATION 39 r\\\,, \ \.­ \0° I ./0° I ••k4A-,..1 (c)•• ~2Ak (b) Fi2ure2.15Polarplotsof(Jr/(JOforthetwo-scatterer complex target(Eq.(2.37)].(a)I=A.;(b)1=2,1.; (c)1=4).. aircrafl28 isshowninFig.2.16.Theaircraft istheB-26,a.WorldWarIImedium-range two-engine bomber. Theradarwavelength was10em.Thesedatawereobtained exper­ imentally bymounting theaircraftonaturntable insurroundings freefromotherreflecting objectsandbyobserving withanearbyradarset.Thepropellers wererunning duringthe measurement andproduced amodulation oftheorderof1to2kHz.Thecrosssectioncan changebyas!Iluchas15dBforachangeinaspectofonly1°.Themaximum echosignal occursinthevicinityofbroadside, wheretheprojected areaoftheaircraftislargest. 
 3.13 («) Logarithmic detector, (b) Nine-stage logarithmic detector. Gain adjustment for each stage is shown below the transistor.STAGE 1LIMITING AMPLIFIERSSTAGE N DET. DET. 
 W. Lawrence, and R. J. 
 Whitehead, A. R. Moore, M. 
 CORRECTING NATURE  THEY DO  NOT REQUIRE COMPONENTS THAT HAVE A WIDE DYNAMIC RANGE OR A HIGH DEGREE OF LINEARITY  AND SO THEY ARE WELL SUITED TO  ANALOGUE IMPLEMENTATION (OWEVER  CL OSED 
 BIT !$# GENERALLY PROVIDES ABOUT  BITS OR ABOUT  D" OF 3.2 #ARRYING  BITS THROUGH THE SIGNAL PROCESSING PROVIDES ABOUT  D" OF DYNAMIC RANGE )N THIS CASE  THE DESIGNER MAY ELECT TO ALLOW THE DATAPATH THROUGH THE LOWPASS FILTER TO REMAIN AT  BITS  REALIZING THAT THE FILTERING PROCESS HAS SIMPLY INCREASED THE 3.2 OF THE SIGNAL TO  D"  WHICH COULD STILL BE ACCOMMODATED BY THE  
 Holtzman, “A simulation study of soil  moisture estimation by a space SAR,” Photogramm. Eng. Remote Sensing , vol. 
 Itsreceiver had asensitivity of about 5X10–13 watts forasignal equal tonoise. The 45-mile ground-painting range oftheAN/APQ-13, ascompared with the25miles required oftheANT/APS- 10,allowed a10-db reduction oftransmitter power forthelatter, iftheantenna gain and thereceiver sensitivity were kept the same. However, itwas felt that a30-in. 
 however, theexactoriginoftheextranoisecomponents isnotimportant excepttoknowthat itexists.Nomatterwhether thenoiseisgenerated byathermal mechanism orbysomeother mechanism. thetotalnoiseattheoutputofthereceiver maybeconsidered tobeequaltothe thermal-noise powerobtained froman"ideal"receiver multiplied byafactorcalledthe"oise figure.ThenoisefigureFnofareceiver isdefinedbytheequation r=~!'-__ =noiseoutofpractical receiver nkToBnG onoiseoutofidealreceiveratstdtempTo(2.4a) whereNo=noiseoutputfromreceiver, andGo=available gain.Thestandard temperature To istakentobe290K.according totheInstitute ofElectrical andElectronics Engineers definition. The1I0iseNoismcasured overthelinearportion ofthereceiver input-output characteristic. 
 PULSE MAINLOBE WIDTH INCREASES FROM  " TO  " WHEN n 
 $ .EXRAD DOPPLER WEATHER RADAR WHERE ITS OPERATING BAND IS FROM  TO  '(Z   AS WELL AS IN OTHER RADARS 6ERY HIGH 
 This  is easily programmed. Multiple receive beams may be formed by combining the subarrays after amplifica - tion in as many different ways as separate beams are required. The limitation is that  the beams have to lie within the beamwidth of the subarray in order to avoid excessive  grating lobes. 
 A balanced mixer uses a hybrid junction, a  magic T, or an equivalent. These are four-port junctions. Figure 9.2 illustrates a magic T in  which the LO and RF signals are applied to two ports. 
 There are many good references that describe the the - ory behind the method and how it is applied to the analysis of reflector antennas.42–44  PO is a very general “high frequency” analysis method that generally provides high  fidelity pattern predictions for most reflector systems as long as the reflector dimen - sions are large, say, greater than about five wavelengths in both dimensions. An over - view of PO is provided here to enable an understanding of the fundamentals of the  method. The PO method can be broken into two steps: (1) the calculation of induced  reflector surface currents, and (2) the integration of these currents (with an appropriate  free space vector Green’s function kernel) to determine the far-field patterns. 
 and Remote Sensing , vol. 29, pp. 444–450, 1991. 
 30 of" Radar Techniques for  Detection, Tracking and Navigation," W. T. Blackband (ed.), Gordon and Breach, New York, 1966. 
 NonLocal Means-based Speckle Filtering for Ultrasound Images. IEEE T rans. Image Process. 
 (/2):/. 2!$!2   Óä°££ PRECEPT THAT EFFICIENCY IS OF LOW IMPORTANCE FOR (& RECEPTION BECAUSE EXTERNAL NOISE  IS ALMOST ALWAYS FAR STRONGER THAN INTERNAL NOISE ! MORE EFFIC IENT RECEIVING ELEMENT  ACCEPTS MORE SIGNAL POWER BUT EQUALLY MORE EXTERNAL NOISE SO   PRIMA FACIE  NOTHING IS  GAINED IN TERMS OF THE SIGNAL 
 image. Thus, the aperture must be provided with more degrees  of freedom than are available from a simple two-element feed. One approach is to utilize  multiple feeds in the vertical plane.48. 
 The technology behind this and  related Russian systems continued to be developed, culminating in the Kondor-E radar  and, through a bilateral technology exchange program, the HJ-1-C SAR of China.12  Both of these radars use the 6-m parabolic reflector developed originally for Priroda,  the final module for the Russian MIR complex. Travers, the radar aboard Priroda,  was an experimental demonstration mission. There are at least three members of the  X-band national asset SAR fleet, including TecSAR13 (Israel) and the IGS-R series  (Japan). 
 E. C. Thompson, “Bistatic radar noncooperative illuminator synchronization techniques,” in  Proc. 
 "._....(..Hyperbolic _.'\<;ubreflecrar --/'//.., talParabola-, neolfocol pointRADAR ANTENNAS 241 \ \ \ \ \ \ \ \ (\f1;perboIO /"Virtual focal ;'point / / I / / / / / (b) Figure7.11(a)Cassegrain antennashowing thehyperbolic subreflector andthefeedatthevertexofthe mainparabolic reflector; (h)geometry oftheCassegrain antenna. TheCassegrain antenna can,ifdesired,bedesigned tohavealowerantenna noisetempera­ turethantheconventional parabolid. Thisisduetotheelimination ofthelongtransmission Jinesfromthefeedtothereceiverandbythefactthatthespillover-sidelobes fromthefeedseethe coldskyratherthanthewarmearth.Lowantenna noisetemperature isimportant inradio astronomy orspacecommunications, butgenerally isoflittleinterestinradarsinceextremely lownoisereceivers arenotalwaysdesirable. 
 148, November 1987. 9. Bhartia, P., and I. 
 Tracking. andNavigation." W.T.Blackband (cd.).Gordon and!Jreach. NewYork.1966. 
 02& SEARCH WAVEFORM THAT MEASURES DOPPLER FRE 
 It has been used in almost all civilian air-traffic  control radars. Pulse-to-pulse frequency agility, however, is not compatible with the use  of doppler processing (to detect moving targets in clutter), but frequency diversity can  be compatible. The frequency range in both agility and in diversity operations is much  greater than the inherent bandwidth of a pulse of width t. 
 A pulse radar for detection of  aircraft might have typically a duty cycle of 0.001, while a CW radar which transmits contin-  ~iously has a duty cycle of unity.  Writing the radar equation in terms of the average power rather than the peak power, wc  get  P,, GA,anEi(n)  Ria, = (4~)~kTo Fn(Bn .r)(SIN)I .fp  The bandwidth and the pulse width are grouped together since the product of the two is  ~~sually of the order of unity in most pulse-radar applications.  If the transmitted waveform is not a rectangular pulse, it is sometimes more convenient to  express the radar equation in terms of the energy E, = Pa,/& contained in the transmitted  waveform:  52INTRODUCTION TORADAR SYSTEMS performance forpartially correlated pulses,interpolation between theresultsforthecorrelated anduncorrelatedconditions canbeusedasanapproximation. 
 The ideal compressed pulse has an amplitude spectrum that exactly matches the fre- quency-weighting function chosen to meet time-sidelobe requirements. Its phase spectrum is linear, corresponding to constant group delay over the band. Amplitude and phase distortion represent a departure of the actual spectrum from this ideal. 
 TRAL DENSITY  Q G(Z  THEN THE ACCELERATION IS SAMPLED BY EACH RADAR DETECTION PRODUCING  A DISCRETE COVARIANCE MATRIX  1T Q44 44 44 KKK KK KK                      44 44 44 KK KK KK   4HE OBSERVATION EQUATION RELATES THE ACTUAL RADAR MEASUREMENTS 9K AT TIME TK TO THE  TARGET STATE   9K   H8TK     NK    WHERE NK IS THE RADAR MEASUREMENT NOISE HAVING A COVARIANCE MATRIX   KR $S S S SQ J        . 
 It is, of . course, evident that any other waveform having a desirable autocorrelation func- tion is equally possible for g(t). The form of g(t) to be analyzed is that of the linearly frequency-modulated case. 
 Since phase shift is periodic with period 2n, it is possible in many  applications to use a phase shifter with a maximum of 2n radians. However, if the pulse width  is short compared with the antenna response time (if the signal bandwidth is large compared  with the antenna bandwidth), the system response may be degraded. For example, if the energy  Figure 8.4 Series arrangements for  applying phase relationships in an  array. 
 Angle (deg) . Ground Range (nmi) FIG. 24.18 A specific example of SNR and clutter-to-noise ratio (CNR) is determined by using Fig. 
 ~0·····•...•./V. 1-1~-;------ -r---t--"."""<::::I----+-lI- -------------+--(c) - 2'-------'-_--'-----'_--'-_-'------"-_-'-_L..-----'--_o2 4 6 8 101214 16 1820 Peakcurrent(A) Figure6.6Performance characteristics ofthecoaxial magnetron. (a)Variation ofpoweroutput, efficiency. 
 45. D. H. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6   blind folio 6.52 ch06.indd   52 12/17/07   2:04:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 R. Ward, Handbook of Radar Measurement , Englewood Cliffs, NJ:   Prentice-Hall, 1969, pp. 256–266. 
 9.28  The Radar Equation in Jamming and Chaff  Conditions  .......................................................  9.29 . This page has been reformatted by Knovel to provide easier navigation. 
 Peake, “Theory of radar return from terrain,” in IRE Nat. Conv. Rec ., vol. 
 DOPPLER RESPONSE  AN INCREASE IN THE TIME SIDELOBES WILL RESULT 5LTIMATELY  IF THE DOPPLER SHIFT BECOMES VERY LARGE  THE MATCHED FILTER RESPONSE WILL DEGRADE 4HIS CAN BE ALLEVIATED BY UTILIZING A BANK OF MATCHED FILTERS  COVERING THE EXPECTED RANGE OF DOPPLER SHIFTS "ECAUSE THIS IS MORE COMPUTATIONALLY INTENSIVE THAN A SINGLE MATCHED FILTER  OLDER RADAR SYSTEMS TEND NOT TO EMPLOY BANKS OF FILTERS 4HE INCREASE IN COMPU 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.596x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 REFERENCES  1. 
 Figure 4.22 illustrates the difference between single-scan and  cumulative probability of detection. ch04.indd   47 12/20/07   4:54:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Tech. Rept. 171, Jan. 
 DOWN ANGLES   CLUTTER DECREASES WITH INCREASING RADAR ALTITUDE SINCE RANGE FOLDING IS LESS SEVERE OWING TO LESS OF THE MAIN BEAM INTERSECTING THE GROUND !T SHORTER RANGES  CLUTTER INCREASES WITH RADAR ALTITUDE SINCE THE CLUTTER PATCH SIZE ON THE GROUND INCREASES 7HILE &IGURE  IS FOR A MEDIUM 
 L., and N. J. Willis: Sanctuary Radar, Proc. 
 withonlyafractionoftheseenergized atanyone timeto formadirective beam.Eachenergized arraye\e'ment wasdrivenfromaseparate power amplifier. whichobtained i'tsproperly phasedinputsignalfromaLuneburg lens.Thislens functioned asalow-power RFanalog beam~formingdevice forthespherical array.Suchalensis sometimes calledacO/llpl/ting lens.Thebeamposition ofthespherical arraywasselected by switching theproperelements oftheLuneburg beam-forming [enstotheelements ofthetrans­ mitarray.EachofthethreeLuneburg-Iens receiveantennas intheradarsystemcouldgenerate a clusterofthreebeamspointing inthedirection ofthetransmit beam.Theangleofarrivalwas extracted bycomparison oftheamplitudes ofthesignalsinthethree-beam cluster.Beam switching wasperformed separately frombeamforming onbothtransmit andreceive.This example ofaradarbasedonmultiple-beam-forming isasystemthatisprobably morecomplex Ihanwouldbeneedednowtoaccomplish thesameradarmission. Another approach tomultiple-beam antennas utilizedaplanarlensarrayfedbyacon­ straincd lensconsisting oftwoconnected hemispherical surfaces andahemispherical feed surface.lizThedetailsofthisantennawillnotbedescribed herc.Itsadvantage islhatithaslrlle timedelay,allowing awideinstantaneous bandwidth. 
 Figure 4: Block diagram of a primary radar with the signal flow  . Radartutorial (www.radartutorial.eu)   5    Figure 5: A typical radar time line    Signal Routing    The radar transmitter produces short duration high -power RF - pulses of energy.    The duplexer alternately switches the antenna between the transmitter and receiver so that  only one antenna need be used. 
 %23 
 BERSOME AND INEFFICIENT ANTENNAS  !T PRESENT  MODERN MONOPULSE RADARS  AS DESCRIBED  IN 3ECTION   PROVIDE HIGHLY STABLE AND EFFICIENT ANTENNAS WITH HIGH PRECISION PERFOR 
 However, when a  planar array is electronically scanned, the change of mutual coupling that accompanies a  change in beam position makes the maintenance of low sidelobes more difficult.  If an array has some margin in performance to permit graceful degradation, it is likely  that this margin will be eliminated during the procurement process if the cost of the radar  escalates. Even if the radar is delivered with margin for graceful degradation, it is likely that  after some time in operation it will always be at the degraded level because of a desire to keep  maintenance costs to a minimum. 
 10.1 Pulse compression radar using (a) conjugate filters, (b) time inversion, and (c) correla- tion.TRANSMITTER MIXER DET WEIGHTING MISMATCHEDSECTIONMATCHEDFILTERSECTION TRANSMITTER MIXER DET WEIGHTINGTIMEINVERSION MISMATCHEDSECTIONMATCHEDFILTERSECTION TRANSMITTER MIXER DET WEIGHTING CORRELATOR MISMATCHEDSECTIONMATCHEDFILTERSECTION . y(t) = ^- flT/MlV^co2W The implementation of Fig. 10. 
  
 K7 MILLIMETER 
 Abramovich, and S. J. Anderson, “Over-the-horizon radar array  calibration using echoes from ionized meteor trails,” IEE Proc. 
 43.Berger.F.B.:TheNatureofDoppler Velocity Measurement, IRETrans.,vol.ANE-4. pp.103-112, September. 1957. 
 A block diagram of a CW radar using  the third harmonic (J3 term) is shown in Fig. 3.17. The transmitter is sinusoidally frequency­ modulated at a frequency fm to generate the waveform given by Eq. 
 Examples of other possible limi - tations to cancellation are listed below34,53,58,59:  1. Mismatch between the main and auxiliary signals including the propagation paths,  the patterns of the main and auxiliary antennas, the paths internal to the system up  to the cancellation point, and the crosstalk between the channels60–62  2. The limited number of auxiliary channels adopted in a practical system as com - pared with the number of jamming signals  3. 
 no. 105.  93. 
 SCINTILLATION NOISE POWER AS A FUNCTION OF TRACKING  ERROR FOR THREE DIFFERENT !'# BANDWIDTHS FROM $UNN  (OWARD  AND +ING  ¡ )2%  . 
 If the radar transmitter is peak-power limited, the  shorter the pulse the less the energy transmitted. This has resulted in short-pulse radars  i~sually being limited in range.  Pulse co~npression is a method for achieving most of the benefits of a short pulse while  keeping within the practical constraints of the peakrpower limitation. 
 The Modiﬁed Phase Screen Simulator for Sliding Spotlight Mode The 2-D scintillation phase screen is typically generated by applying the Gaussian noise with unit power passes through a linear ﬁlter with a speciﬁed PSD. Some research has been accomplished to study the ionospheric spectrum including the Shkarofsky spectrum, the modiﬁed Kolmogorov spectrum, and Rino power law spectrum. The Rino’s spectrum has been proved by real measured data and widely used in global ionospheric scintillation model (GISM) and wide band model (WBMOD) [ 24,27]. 
 The MTD radar transmits a group of N pulses at a constant pulse repetition frequency (PRF) and at a fixed radar frequency. This set of pulses is usually re- ferred to as the coherent processing interval (CPI) or pulse batch. Sometimes one or two additional fill pulses are added to the CPI in order to suppress range- ambiguous clutter returns, as might occur during periods of anomalous propaga- tion. 
 Record, vol. 1, pt. 3, pp. 
 3 7  The branch-type duplexer is oflimited bandwidth and power-handling capability, and has  generally been replaced by the balanced duplexer and other protection devices. It is used, in  spite of these limitations, in some low-cost radars.  Balanced duplexers. 
 Rept. 389. May 17. 
 / %ARTH 3URFACE #LUTTER  4HE GEOMETRY OF SKYWAVE ILLUMINATION ENSURES THAT TAR 
 21.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 21.5 GPR SYSTEMS The choice of system design is to a large extent governed by the type of target, the res - olution required, and the anticipated ground attenuation and clutter. The depth range of  the radar system is likely to be primarily defined by the soil attenuation, once a particu - lar range of frequencies has been chosen. However, it can be shown that considerable  variations (10–30 dB) in the sensitivity of competing system designs actually translate  to relatively small changes in depth performance in lossy soils. 
 PEARS 6IDEO STAGES ARE MOST VULNERABLE AND TAKE LONGER TO RECOVER THAN )& STAGES SO IT IS CUSTOMARY TO INCLUDE A LIMITER IN THE LAST )& STAGE  DESIGNED TO QUICKLY REGAIN NORMAL OPERATING CONDITIONS IMMEDIATELY FOLLOWING THE DISAPPEARANCE OF A LIMITING SIGNAL ,IMITING PRIOR TO THE !$ CONVERTER ALSO PREVENTS THE DISTORTION THAT OCCURS WHEN SIGNALS EXCEED FULL 
 The antenna gain does not enter, except as it is affected by the azimuth beamwidth 0,.  The narrower the pulse width the greater the range. This is just opposite to the case of  conventional radar detection of targets in noise. 
 TION  CAN BE CONSIDERED A FUNCTION OF THE DURATION OF THE COMPLEX ENVELOPE OF THE SIG 
 RFpoweroutput-RFdrivepowerlclency= .d-cpowermput(6.1) Thisisaconservative definition sincetheRFdrivepowerisnotlostbutappears aspartofthe output.. 212 INTRODUCTION TO RADAR SYSTEMS  The low insertion loss of a CFA can be of advantage in systems that require marc tt1a11  one radiating power level. By omitting tile-application of d-c voltage to the final stagc, the  lower level RF drive-power can be fed through the final stagc with little attcni~atiorl. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.536x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 ● Provide a response of −46 dB for chaff rejection at velocities between ±20% of the  ambiguous doppler frequency range. ● In this design, only five filters will be implemented. 
 38. R. K. 
 BIASED STAGES ARE CASCADED IN SERIES  AS IS COMMON IN MOST AMPLIFIER CONFIGURATIONS 4HE FINAL TIER OF OUTPUT TRANSISTORS IN A SERIAL AMPLIFIER CHAIN  MUST BE DRIVEN INTO SATURATION BY THE  PRECEDING STAGES  AND THE DRIVE LEVEL MUST BE HELD RELATIVELY CONSTANT AS A FUNCTION OF TIME AND TEMPERATURE 3INCE THESE DEVICES EXHIBIT THIS NARROW OPERATING RANGE   SMALL DECREASES IN THE INPUT 2& DRIVE LEVEL TO A MULTISTAGE AMPLIFIER MAY BRING THE  FINAL TIER OF DEVICES OUT OF SATURATION &AILURE TO CONTROL THESE CONDITIONS ACCURATELY CAN RESULT IN UNACCEPTABLY DEGRADED OUTPUT PULSE FIDELITY )N A VERY SIMPLE SENSE  THE DESIGN OF AN AMPLIFIER MODULE CONSISTS OF MATCHING THE  POWER TRANSISTORS TO THE PROPER IMPEDANCE LEVEL AND THEN COMBINING THE POWER LEVELS AT THESE IMPEDANCES ! TYPICAL PACKAGED POWER TRANSISTOR HAS LOW INPUT AND OUTPUT IMPEDANCES THAT MUST BE TRANSFORMED UP TO HIGHER LEVEL  USUALLY  OHMS 4HUS  THE TYPICAL AMPLIFIER DESIGN TASK MUST ADDRESS BOTH LOW 
   AND!.-03 
 ITY OF DETECTION   0D CUM  WHICH IS DEFINED AS THE PROBABILITY THAT THE RADAR WILL DETECT  A CLOSING TARGET AT LEAST ONCE BY THE TIME THE TARGET HAS CLOSED TO A SPECIFIED RANGE 0 D CUM IS ONLY DEFINED FOR CLOSING  TARGETS 4HE CUMULATIVE PROBABILITY OF DETECTION FOR  THE KTH SCAN  OR FRAME  IS  0K 0 I 0K 0DD IK D    ;= ; ;= = ;=CUM SS CUM 
 COMPARISON  MONOPULSE  (OWEVER   THE BASIC SIGNAL PROCESSING OF AMPLITUDE 
 Pratt and D. G. Ferraro, “Automated solar gain calibration, preprints,” in 24th Conf. 
 LEM IS CALLED  NTH 
 MIZE THE AMOUNT OF JAMMING ENERGY ACCEPTED BY THE RADAR 4HIS IS ACCOMPLISHED BY SPREADING THE TRANSMITTED FREQUENCY RANGE OF THE RADAR OVER AS  WIDE A BAND AS POS 
 Internal and external fans are provided forthe unit inwhich there isthe greatest heat dissipation-the transmitter-receiver. The internal rise above ambient temperature inthk unit is35”C. Allunits except thescanner areshock-mounted. 
 ~. o 0 .~.,::-:::::::-:::"'---- ._---~~~~ ,-------THERADAR EQUATION 43 Figure2.20SameasFig.2.19,butforcircu­ larpolarization. RR=right-hand polariza­ tion,LL=left-hand polarization; RLand LRarecross-polarized components. 
 # IS THE FIRST OF FIVE 3!2 SATELLITES IN #HINAS SMALL SATELLITE  PROGRAM  ANNOUNCED IN  FOR ENVIRONMENT AND DISASTER MONITORING 4HE  ARCHI 
 Ocean. Tech. , 17,   pp. 
 It is superior to a strictly narrowband loop followed by a shaped amplifier even for CW measurements. 14.6 RECEIVERS RF Amplification. Although it is apparently attractive, low-noise RF amplification of the received signal has not been extensively employed in CW radar. 
 We can obtain the RCS amplitudes R(k)follow the angle θ(k)from curves as shown in Figure 2, where k=1, 2,···,n. The pseudo-probability P(k)of scattering in θ(k)can be calculated by P(k)=R(k) ∑n k=1R(k). (1) Then, aspect entropy is deﬁned as Ha=−n ∑ k=1P(k)lognP(k). 
 Table 1.1 lists the radar-frequency Jetter-band nomenclature adopted by the  IEEE.1 s These are related to the specific bands assigned by the International Telecommunica­ tions Union for radar. For example, although the nominal frequency range for L band is 1000  to 2000 MHz, an L-band radar is thought of as being confined within the region from 1215 to  1400 MHz since that is the extent of the assigned band. Letter-band nomenclature is not a  Wavelength  10km l km 100 m 10m 1m 10cm fem 1mm O.lr.im  +--VLF LF MF HF VHF UHF SHF EHF  Very low Low Medium High VeryhiQh  frequency frequency frequency frequency frequency  I Ultrohigh Super Extremely  frequency high high  frequency frequency  Mydometric Kilometric Heclometric Decometric Metric Decimetric Centi metric Mi!limetric Decimilli- waves woves waves waves waves waves waves waves metric waves  Bond 4 Band 5 Bond 6 Bond 7 Band 8 Bond 9 Bond IO Bond 11 Bond I 2  ___ Au_d_lo_fr_eq_u_,n_d_es ... 
 4.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 FIGURE 4.10  Two-channel sidelobe blankerDetection LogicSquare Law DetectorMain Channel CFAR Main-To- Guard Ratio ThresholdPost Detection IntegrationMatched Filter and Doppler Filterbank (FFT)Main Channel Antenna Guard Channel AntennaSquare Law DetectorGuard Channel CFARPost Detection IntegrationGuard Channel ReceiverMatched Filter and Doppler Filterbank (FFT)Detections Out 0 → No Detect  1 → DetectMGRM GMain Channel Receiver M 0  0 0 0  1  1 1  10  0 1  1  0 0 1  10  1 0  1  0 1  0  1No No No  No  Yes  Yes  No  YesG MGR Detect? ch04.indd   20 12/20/07   4:52:41 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 VEILLANCE  n !MPLITUDE COMPARISON MONOPULSE SYSTEMS  ILLUS 
 An alternative approach is the solution of the integral equations governing the dis - tribution of induced fields on target surfaces. The most useful approach to a solution  is known as the method of moments , in which the integral equations are reduced to  a system of linear homogeneous equations. The attraction of this method is that the  surface profile of the body is unrestricted, allowing the computation of the scattering Chapter 14 ch14.indd   1 12/17/07   2:46:43 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 ," 
 Critical applications are  usually only the front-end switching configurations in a T/R module, i.e., before the  receive low-noise amplifier or after the transmit amplifier. Phase Shifters.  (1) Digitally controlled phase-shifter designs generally uti - lize either a switched-line or a loaded-line circuit configuration, using either  distributed transmission-line components or lumped-element equivalent circuits,  to achieve multiple-bit phase shifting. 
 ITY HAS BEEN DESCRIBED FOR A DWELL OF THREE #0)S AND THE ASSUMPTION THAT EACH TARGET  WILL HAVE A RETURN FOR EACH OF THE THREE #0)S )N PRACTICE  THIS ASSUMPTION IS NOT ALWAYS VALID  AND THE ACTUAL IMPLEMENTATION MAY CHOOSE  FOR EXAMPLE  TO HAVE THE DWELL CON 
 THICKNESS RADOMES 4HIN LAYERS OF METAL INCLUSIONS EXHIBIT THE CHARACTERISTICS OF LUMPED CIRCUIT ELEMENTS SHUNTED ACROSS A TRANSMISSION LINE &OR EXAMPLE  A GRID OF PARALLEL METAL WIRES EXHIBITS THE PROPERTIES OF A SHUNT 
 flight path or from the changing aspect caused by target motion. In essence, angle fluctuations  are a distortion of the phase front of the echo signal reflected from a complex target and may be  visualized as the apparent tilt of this phase front as it arrives at the tracking system.  Equation (5.2) indicates that the tracking error 6.0 due to glint for the two-scatterer target  is directly proportional to the angular extent of the target 00. 
 Therefore, rms angle noise sang is expressed in  ch09.indd   30 12/15/07   6:07:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 
   A RELATIVELY MODEST CAPABILITY 5(& RADAR FOR AIR SURVEILLANCE  4HIS RADAR WAS CHOSEN FOR HAVING ITS VACUUM TUBE TRANSMITTER  REPLACED WITH A SOLID 
 Further melting cannot lead to much further enhancement, apparently, and may lead to a lessening of the reflectivity of the particle by bringing it to sphericity or by break- ing up the particle. Melting of ice particles produces enhanced backscatter, and this effect gives rise to the radar-observed bright band near the O0C isotherm. Attenuation by Fog. 
   -AY   .AVAL 2ESEARCH ,ABORATORY  7ASHINGTON  $#  HTTPSSIMDISNRLNAVYMIL  SIMDIS ENEWSNRL  NAVYMIL  , 6 "LAKE   2ADAR 2ANGE 0ERFORMANCE !NALYSIS   ,EXINGTON  -! ,EXINGTON "OOKS  $#  (EATH AND #O  .     I_1 INDEX A A-12 low cross section aircraft, 14.40 Absorbers, 14.32, 14.36 to 14.38 Active aperture, 13.53 to 13.55 Active Electronically Scanned Array (AESA), 5.1, 5.8 to 5.10, 10.28 compared to mechanical scan, 5.9 to 5.10 timing structure, 5.15 to 5.16 typical waveform parameters, 5.13, 5.15 waveform variations for air-to-surface mode, 5.12 to 5.13 Active jamming, 24.5 Active-switch modulator, 10.24 A/D converter and MTI dynamic range, 2.78 to 2.80 Adaptive arrays (ECCM), 24.20 to 24.30 Adaptive jammer and clutter cancellation, 24.25 Adaptive MTI, 2.80 to 2.83 Adaptive thresholding, 7.11 to 7.19 Advanced Propagation Model (APM), 26.16 to 26.17 Advanced Refractive Effects Prediction System (AREPS), 26.1 to 26.2, 26.18 to 26.27 Aid to Navigation (AtoN), 22.25 to 22.26 Air-to-air ground ranging, 5.33 Air-to-air mission profile, 5.12 to 5.14 A ir-to-air modes, 5.14, 5.16 to 5.28 medium PRF, 5.16 to 5.20 Air-to-surface mission profile, 5.10 Air-to-surface mode suite, 5.11 to 5.12 Air-to-surface radar modes, 5. 28 to 5.42 Air-traffic control (ATC) radar, 1.21 to 1.22 Air Traffic Control Radar Beacon System (ATCRBS), 7.49 Airborne Early Warning, 3.1. 
 Polarization. Raindrops are spherical, or nearly so, but aircraft are complex targets. Tllus the  backscattered energy from rain and aircraft will be affected differently by the polarization of  the incident radar energy. 
 !DAPTIVE 1UANTIZER  "!1  4HIS IN  EFFECT IMPLEMENTED AN AUTOMATIC GAIN CONTROL !'#  THAT SELECTED THE MOST INFLUENTIAL DIGITAL SAMPLES BITS  FROM THE RAW 3!2 DATASTREAM !S DESIGNED FOR  -AGELLAN  THE  DATA WERE DIGITIZED INTO  BITS  IN 
 In Earth-oriented  remote sensing radars, typical combinations include HH and HV , for example,  or HH and VV (which requires two separate transmit polarizations). The ASAR  aboard ENVISAT is the first space-based example of this type of polarization  diversity. If the four (linear) polarization possibilities are exploited noncoher - ently, then the backscattering function of the scene may be characterized by the  three backscatter coefficients ( s  0 HH, s  0 VH, s  0 VV), which, of course, are devoid of  phase. 
 2. (It will be seen in  Scc 13.3 that a dccrcase 111 pulse width call cllangc tlie nature of the clutter statistics it1 sorlie  cases arld niiglit negate tile benefits of tile greater signal-to-clutter ratio obtained with the  sllort pulse.) The improvement in range due to tile integration of 11 pulses is not indicated in  tlliq ccli~atiotl. .l'llcre call t,c a co~~sidcrahle diffcrcncc in the integration irnprover~~etlt wlle~l  clutter-limited from when noise-limited. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters.  SOLID-STATE TRANSMITTERS  11.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 of a FET is delineated by any of several patterning techniques on a semi-insulating  GaAs substrate such as ion implantation or molecular beam epitaxy. 
 This is a consequence of the fact that both the time delay (range) and the  frequency (doppler) are both determined by measuring a frequency shift. Thus neither  the range nor the velocity can be determined without knowledge of the other.  This limitation can be overcome by transmitting a second FM pulse whose slope on the  ambiguity diagram is different from that of Fig. 
 Popov, G. P.: "Engineering Psychology in Radar," JPRS-55522, Joint Publications Research Service,  Washington, D.C., 23 March, 1972.  62. 
 FromEq.(9.12b)thenoisefigureofthemixerisFe=(rLe.This,however, isnota complete measure ofthesensitivity ofareceiver withamixerfront-end. Theoverallnoise­ figuredepends notonlyonthemixerstage,butalsoonthenoisefigureoftheIFstageandthe mixerconversion loss.Itmaybedetermined fromtheexpression forthenoisefigureoftwo networks incascade [Eq.(904)].Thefirstnetwork isthemixerwithnoisefigure (rLeand gain=I/Le•Thesecondnetwork istheIFamplifier withanoisefigureFIF.Thereceiver noise-figure withamixerfront-end isthen F2-IF0=F1+G1=Le(tr+FIF-I) (9.13) (Thisdoesnotinclude lossesintheRFtransmission lineconnecting ther~eiver tothe antenna.) If,forexample, theconversion lossofthemixerwere6.0dB,theIFnoisefigure1.5dB, andthenoise-temperature ratiolA,thereceiver noisefigurewouldbe8.6dB.Forlow-noise­ temperature-ratio diodes,thereceiver noisefigureisapproximately equaltotheconversion losstimestheIFnoisefigure. Balanced mixers.Noisethataccompanies thelocal-oscillator (LO)signalcanappearattheIF frequency because ofthenonlinear actionofthemixer.TheLOnoisemustberemoved if receiversensitivity istobemaximized. 
 If the transmitted waveform is not a rectangular pulse, it is sometimes more convenient to  express the radar equation in terms of the energy Ei = PavUp contained in the transmiued  waveform:  4 E,GAe«nEi(n)  Rmax = (41t)2kT0Fn(Bnt)(S/N)1 (2.44b) . THE RADAR EQUATION 53  In this form. the range does not depend explicitly on either the wavelength or the pulse  repetition frequency. 
 These bands can be used for additional information,  and processing results for moving targets will be different from those for fixed  targets. Freeman39 presents a summary of potential results for moving targets, cov - ering such issues as azimuth shift, range walk, and azimuth defocus: “Probably  the worst defect...will be displacement of moving targets in the azimuth direction,  away from their true position on the ground. The prefilter we have described is  optimised for targets traveling radially...Such targets will appear at their correct  position in the MTI image.” Interferometric SAR (InSAR) for Moving Target Indication (MTI)  As  mentioned in Section 17.3, Interferometric SAR (InSAR, sometimes also called  IFSAR) refers to the use of two antennas whose signals are combined coherently. 
 +~~w,nd + &.m.rn); ‘, (27) since the three fluctuations are independent ofeach other. A-ow each fluctuation isproportional tothesize oftheclutter. Thus wehave R,= 1— ( )),~ (28)s ~+~1 K~n’ <K;A2j~ +E: where the terms inthe denominator refer respectively tothe effects of scanning, wind, and system instability. 
 TION IS GIVEN BY   44 4,2   $    THE ,/ REFERENCE CHIRP WAVEFORM BANDWIDTH IS GIVEN BY   "44 4",2 22   $    AND THE )& PROCESSING BANDWIDTH IS GIVEN BY   "4 4") 22 $    È°{Ê , 
 3.4 and 3.5, and to integrate the total power in the doppler residue spec- trum, with the exception of modulation frequencies below 100 Hz, which cannot be measured. The result (51.8 dB) is the MTI improvement factor limitation due to stalo instability. Figure 3.7 shows the same measured stalo modulation spectrum, subjected to a range delay of 1200 jxs. 
 54  8.6 Filterbank Procedure ....................................................................................................... 56  8.7 Impulse Integration for Increasing the Sensitivity .......................................................... 58  8.7.1 Incoherent Integration ............................................................................................... 
 Itisintroduced directlyintothereceiver viaacableorotherdirectconnection. >­u c Q) ::Jcr Q).....u.. fofL----"'-=-------------------Time- (a) rb.f (e)Figure3.10Frequency-time relation­ shipsinFM-CW radar.Solidcurve represents transmitted signal;dashed curverepresents echo.(a)Linearfre­ quencymodulation; (b)trianguJar fre­ quencymodulation; (c)beatnoteof (b).------1/1. 
 See the text for a description  of radar parameters. ch20.indd   61 12/20/07   1:17:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The radome skin may be rigid, supported by a  framework, or air-supported. The most common rigid radome-wall structures are shown in Figure 12.39 and are  known as homogeneous single layer, A-sandwich, B-sandwich, C-sandwich, multiple- layer sandwich, and dielectrics with metal inclusions. ch12.indd   39 12/17/07   2:32:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
  !$ !   &EBRUARY    7 ( 0ERKINS AND 4 ! -IDFORD  h--)# TECHNOLOGY BETTER  PERFORMANCE AT AFFORDABLE COST v  -ICROWAVE *  VOL   PP n  !PRIL    " #ANTRELL  * DE 'RAAF  & 7ILLWERTH  ' -EURER  , ,EIBOWITZ  # 0ARRIS  AND 2 3TAPLETON   h$EVELOPMENT OF A DIGITAL ARRAY RADAR v )%%% !%%3 3YSTEMS -AGAZINE  PP n  -ARCH   ( 3TEYSKAL  h$IGITAL BEAMFORMING ANTENNAS AN INTRODUCTION v  -ICROWAVE *  PP n   *ANUARY   2 # (ANSEN  0HASED !RRAY !NTENNAS  .EW 9ORK *OHN 7ILEY  3ONS   ( 3TEYSKAL  2 ! 3HORE  AND 2 , (AUPT  h-ETHODS FOR NULL CONTROL AND THEIR EFFECTS ON THE  RADIATION PATTERN v  )%%% 4RANS !NTENNAS AND 0ROPAGATION   VOL !0 
 ,- )N ITS MOST GENERAL FORM  A RADAR SOUNDER IS A DEVICE WHOSE TRANSMISSIONS ARE DESIGNED  TO PENETRATE THE VOLUME OF A TARGET MEDIUM  FROM WHICH THE WAVEFORM OF THE RESULTING BACKSCATTER INDICATES VARIATIONS IN DIELECTRIC CONTRASTS AS A FUNCTION OF DEPTH o !S A  SOUNDER PASSES OVER AN ILLUMINATED REGION  THE SEQUENCE OF RANGING WAVEFORMS GENER 
 From Figure 2, we can see that the red and blue broken lines show good consistency, indicating that the estimated parameters were in good agreement with the true values. Table 1shows the quantitative comparisons of RMSE (root mean square error) for each unknown parameter in Figure 2. For the four unknown parameters, the magnitude of errors accounted for lower than 6% of the mean parameter estimations. 
 The condition of the simulation is a more ideal than an anechoic chamber experiment. Figure 1shows the models of the four canonical shapes. The results of the simulation are shown in Figure 2. 
 269-271. March. 1975. 
 178, 186  Uncertainty relation. 408-409  lJ nequally spaced arrays. 331 -332  Unfocused SAR, 518-519  I fniform prohahility density function, 21-22  l I nigrid. 
 CRT screem. A number of different cathode-ray-tube screens are used in radar applications.  They differ primarily in their decay times and persistence. 
 ALLY  RADAR FREQUENCIES MIGHT BE FROM ABOUT  -(Z TO OVER  '(Z 4HIS IS A VERY LARGE EXTENT OF FREQUENCIES  SO IT SHOULD BE EXPECTED THAT RADAR TECHNOLOGY  CAPABILITIES  AND APPLICATIONS WILL VARY CONSIDERABLY DEPENDING ON THE FREQUENCY RANGE AT WHICH A RADAR OPERATES 2ADARS AT A PARTICULAR FREQUENCY BAND USUALLY HAVE DIFFERENT CAPABILI 
 #(),, v PRESENTED AT  CD #ONF 2ADAR -ETEOROL    02  !-3  !LBUQUERQUE    2 % #ARBONE  - #ARPENTER  AND # "URGHART  h$OPPLER RADAR SAMPLING LIMITATIONS IN CONVEC 
 TRACKING 
 Inpractice, thereareregionsoflandwherethecluttermightbeconsiderably greaterthantheaverage andregionswhereitisconsiderably lessthanaverage.Iftheresolu­ tionoftheradarisgreatenoughtoresolvetheareasoflowerclutterfromtheareasofgreata ciUlla,targetswithintheclearareascanoftenbedetected andtrackedcvcnthoughitmightbe predicted onthebasisoftheaverage clutter aOthatitwouldnotbepossible. Theabilityofsomeradarstoresolvethestrongclutterregionsintodiscrete areas,be­ twecnwhichtargetsmaybcdetected, iscalledimerclllttt'l' uisihility. Itisdifficult toestablish a quantitative measure ofthiseffect;butithasbeensuggested~2 thattheimprovement intarget detectability canbeapproximated bytheratiooftheaverage clutterleveltothemedian clutter,whichcanbeasmuchas20dBforamedium-resolution radar(forexample,6~ onewith a 2I~Spulsewidthanda1.5°beamwidth). 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar.  GROUND PENETRATING RADAR  21.376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 Abandoned antipersonnel land mines and unexploded ordnance are a major hin - drance to the recovery of many countries from war. 
 An adjunct oblique sounder can provide information in  FIGURE 20.28  The numbers in this figure show the SNR in dB as a function of frequency and range in  the form of a typical oblique backscatter sounding: January, 1800 GMT (day), SSN 50, location 38.65 °N and   76.53 °W, bearing 90 °. See the text for a description of radar parameters. ch20.indd   60 12/20/07   1:17:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Experimental Results and Discussions Experimental results based on real SAR images are presented in this section to quantitatively evaluate the validity of the proposed method. The experimental data include spaceborne and airborne SAR data. The parameters of the SAR images are presented in Table 1. 
 ENCE BETWEEN THE ACTUAL ATTENUATION AND THAT COMMANDED BY INJECTING TEST SIGNALS DURING DEAD TIME )N THE PAST  GAIN CONTROLLED AMPLIFIERS WERE USED EXTENSIVELY TO CONTROL AND ADJUST  RECEIVER GAIN 2ECENTLY  THIS APPROACH HAS LARGELY BEEN REPLACED USING DIGITAL SWITCHED OR ANALOG VOLTAGE OR CURRENT  CONTROLLED ATTENUATORS DISTRIBUTED THROUGHOUT THE RECEIVER CHAIN 6ARIABLE ATTENUATORS HAVE A NUMBER OF ADVANTAGES OVER VARIABLE GAIN AMPLIFI 
 Thus, if each scatterer is a tree, the waving of the trees as the wind blows causes relative phase shifts between the separate scatterers; the result is fading. For a fixed radar, this may be the only fading observed, except for very slow fading due to changes in refraction. For a moving radar, this motion of the target changes the relative velocities between target element and radar, so that the spectrum is different from that for a fixed surface. 
 (Courtesy of Walter W. Lund, Jr., The Boeing Company.) The physical optics formula for the RCS of a circular metallic disk is A cos 0 J\(kd sin 6) 2 i^ •**. vcjs \j i^ ' ,+ + ifYva = 16ir — • . 
 This permits the use ofasingle antenna and also reduces theclutter intensity bymaking itpossible togate outthe strong returns from near-by objects. Difficulties with systems ofthis type areasfollows: (1)determination ofrange byvariation ofjrtakes much more time than isjustified byt,he receiver bandwidth; (2) the distance measurement isunambiguous ordy over a2-to-1 range; (3)proportions must besuch that jD <j,—this means long wavelengths and/or slow targets; (4)itisdifficult togetthe modulation cycles torepeat well enough forsuppression ofreally serious clutter. 6.11. 
 MTT-23, pp. 818-825, October, 1975.  48. 
 ( 11.3) follows from  the fact that the video signal-to-noise power ratio is equal to twice the IF signal-to-noise  power ratio (S/ N), assuming a linear-detector law and a large signal-to-noise ratio.  If the rise time or the video pulse is limited by the bandwidth B of the IF amplifier, then  t,:::::;; 1/B. Letting S = E/r and N = N0 B, where Eis the signal energy, N0 the noise power per  unit bandwidth, and r the pulse width, the error in the time delay can be written  ( r ) 112  bTR = 2BE/N0 ( 11.4)  If a similar independent time-delay measurement is made at the trailing edge of the pulse, the  two combined measurements will be improved by )2, or  ( r )112  bTR = 4BE/N0 rectangular pulse ( 1 l.5)  For constant pulse amplitude A, the rms time-delay error given by Eq. 
 AP-12.  pp. 781 782. 
 BASED SYMMETRICAL .,&- WAVEFORM     7EIGHTING4ARGET 2ADIAL  6ELOCITY MS   0EAK 43, D" !VERAGE  43, D"   &ILTER -ATCHING ,OSS D"  ,&- UNWEIGHTED     
 Kalmykov, I. E. Ostrovsky, and A. 
  AND OFF 
 -(Z RADAR OPERATING AT  PPS .   -4) 2!$!2  Ó°££ WAVEFORM AND PROCESSING  AVAILABLE DYNAMIC RANGE  AND THE OVERALL RADAR SYSTEM STA 
   #)6), -!2).% 2!$!2   ÓÓ°Îx  2 'ANGESKAR  h!UTOMATIC OIL 
 Thus, each filter out put is averaged over one mile in range  to establish the statistical mean level of nonzero-velocity clutter (such as rain) or noise. The  filter thresholds are determined by multiplying the mean levels by an appropriate constant to  obtain the desired false-alarm probability. This application of an adaptive threshold to each  doppler filter at each range cell provides a constant false-alarm rate (CF AR) and results in  subweather visibility in that an aircraft with a radial velocity sufficiently different from the rain  so as to fall into another filter can be seen even if the aircraft echo is substantially less than the  weather echo. 
 TO 
 17.15 Modulator A B c D E F G H I J K*3300Psec~i I -n_.._n._.n_n___r ~---~ —-~—--w&&imM.M— ——~ - MTl — Lower—MTI— Lower— MTI— Lower— MTI- Lower— MTI beam beam beam beam -uL__.__L.___.__uL__ -_JIL__.-._lL_ -1------ --- -_-J_--——__— l___ ___—--_-_-J——____ i___i__.L___L___i -iii___.uiii_._diIi__JiIi__JiL J-----L-- __-r---l -_l_____--L-___ -l––––~___. L ‘If-~02 6 30jasec Modulator oulse Fu;:vth Ete%on Videoswitch Video Mcode‘ pulse signal pulse I N o P-l----l--- ----_r---l FIO. 17.20 .+round-to-. 
 ('onvcrsion lossandnoise-temperature ratio.Theconversion lossofamixerisdefined as available RFpowerL=---------c----- Cavailable IFpower Itisameasure oftheefficiency ofthemixerinconverting RFsignalpowerintoIF.The conversion lossoftypical microwave crystals inaconventional single-ended mixer configuration variesfromabout5to6.5dB.Acrystal mix~riscalled"broadband" whenthe signalandimagefrequencies arebothterminated inmatched loads.Asignalimpressed in theRFsignalchannel ofabroadband mixerisconverted inequalportions totheIFsignaland theRFimage.Therefore thetheoretical conversion losscanneverbelessthan3dBwiththis configuration. (Theimagefrequency isdefinedasthatfrequency whichisdisplaced fromthe localoscillator frequency fLObytheIFfrequency, andwhichappears ontheopposite sideof thelocaloscilfator frequency asthesignalfrequency filF'Itisequalto2fLO-fRF') Short-circuiting oropen-circuiting theimage-frequency termination resultsina"narrow­ band"mixer.Theconversion lossislessinthenarrowband thaninthebroadband mixer.In principle, itcanbeabout2dBlower.6Thedesignofabroadband mixerhasbeensimplerto achieveandlesscriticalthananarrowband mixer. The/loise-temperature ratioofacrystalmixer(nottobeconfused witheffective noise temperature) isdefined as oractualavailable IFnoisepowert=..-..'---"....-.----------.- ravailable noisepowerfromanequivalent resistance t=Fc~!jJ.BnS =FG=Fe rkToBnCCLc(9.12a) (9.12b) whereFc=crystalmixernoisefigureandLc=1/Ge=conversion loss.Thenoisetemperature ratioofacrystalmixervariesapproximately inversely withfrequency fromabout100kHz(the exactvaluedepends uponthediode2S)downtoasmallfractionofahertz.Thisiscalledfiicker. 
 YEAR DESIGN LIFE 2!$!23!4 
 The  numerator, s, of the second factor is the radar cross section of the target. It has the unit  of area (for example, square meters) and is a measure of the energy redirected by the  target back in the direction of the radar. The denominator of the second factor accounts  for the divergence of the echo signal on its return path back to the radar. 
 44. White, J. F.: "Semiconductor Control," Artech House, Dedham, Mass., 1977. 
 DIMENSIONAL VECTOR WIND FIELDS    &IGURE  IS A BLOCK DIAGRAM OF THE "INET )NC 
  PATTERN IN &IGURE  WAS MEASURED AT A FREQUENCY OF  '(Z 4HE POLAR FORMAT  IS USEFUL FOR DISPLAY PURPOSES BUT IS NOT AS CONVENIENT FOR DETAILED COMPARISONS AS IS A RECTANGULAR FORMAT LIKE THE ONE USED IN &IGURE  4HAT RECTANGULAR PATTERN IS OF A ONE 
 GROUND PENETRATING RADAR  21.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 The principle of the sampling receiver is, therefore, a downconversion of the radio  frequency signal in the nanosecond time region to an equivalent version in the micro-  or millisecond time region. The incrementation of the sampling interval is terminated  at a stage when, for example, 256, 512, or 1024 sequential samples have been gathered.  The process is then repeated. 
 PLACEMENT BETWEEN SUPPORTS WITH  A CUSP BETWEEN SUPPORTS. £Ó°£{  2!$!2 (!.$"//+  WELL 
 Interferometric ArcSAR extraction the DEM image of scenes. 6.2. Distributed Scenes Imaging Simulation Experiment V eriﬁcation the DEM-Assisted High Precision Imaging Method for ArcSAR We used the distributed scenes imaging simulation experiment to image the scenes given in Experiment 1. 
 but with the consequence that the frequency measurement is ambiguous and results in  blind speeds, Eq. (4.8). The pulse doppler radar, on the other hand, has a high pulse repetition  frequency that avoids blind speeds, but it experiences ambiguities in range. 
 TERM COHERENT CHANGE DETEC 
 In this chapter, improvement  factor  and clutter attenuation  will be used synonymously. When the coherent gain of the  doppler filter is included, the term signal-to-clutter ratio  improvement will be used. Clutter Attenuation  The IEEE definition reads clutter attenuation (CA):  In moving-target indication (MTI) or doppler radar, the ratio of  the clutter-to-noise ratio at the input to the processor, to the clutter-to-noise ratio at the out - put. 
 0ULSE ,OW 
 MISSION )F WEIGHT IS AN IMPORTANT CONSIDERATION  AS IT WOULD BE IN A SPACE 
 £ 
 K.. arid R. J. 
 von Schlachta, K.: A Contribution to Radar Target Classification, International Cot$erence  RADAR-77, Oct. 25-28, 1977, pp. 135-139, IEE (London) Conference Publication no. 
 From the user’s perspective, it may seem logical to measure  performance in terms of time taken to establish a track on a given target, averaged  over time and coverage, since tracks are the essential product delivered to users  by the radar. Of course, this places the onus on the tracking system, so one might  step back a little and choose instead SNR achievable on a given target, again aver - aged over time and coverage. But this ignores the precision of the measurement,  associated with both resolution, which may impact on the utility of the detections,  and accuracy, in the sense of registration in absolute (geographical) coordinates. 
 £ä°Óä  2!$!2 (!.$"//+  ELECTROMAGNETIC COMPATIBILITY PURPOSES TO AVOID TRANSMITTING ENERGY BEYOND THOSE  LIMITS 4HIS OBJECTIVE MAY BE APPROACHED BY USING A PULSE SHAPE DIFFERENT FROM THE CONVENIENT AND CONVENTIONAL RECTANGULAR PULSE  (IGHLY SHAPED PULSES HAVE NOT  BEEN USED OFTEN IN RADAR SYSTEMS BECAUSE OF THE LOSS OF EFFICIENCY THAT RESULTS 4HESE LIMITATIONS  HOWEVER  DO NOT APPLY WHEN USING THE GRID 
 BAND 3!2 IMAGES v  )%%% 4RANS ON 'EOSC AND 2EMOTE 3ENSING   VOL '% 
 Assume that the noise-like component of the sidelobes is down 50 dB from the  peak transmitted signals. This noise-like component will not cancel in the MTI sys - tem, and therefore, for each clutter area that exceeds the system threshold by 50 dB  or more, the residue will exceed the detection threshold. If the clutter exceeds the  threshold by 70 dB, the residue from the MTI system will exceed the detection  threshold by 20 dB, eliminating the effectiveness of the MTI. 
 TheFM-CW radarprinciple isusedintheaircraft radioaltimeter to measure heightabovethesurfaceoftheearth.Thelargebackscatter crosssectionandthe relatively shortrangesrequired ofaltimeters permitlowtransmitter powerandlowantenna gain.Sincetherelative motion between theaircraftandground issmall,theeffectofthe doppler frequency shiftmayusuallybeneglected. Thebandfrom4.2to4.4GHzisreserved forradioaltimeters, allhough theyhaveinthe pastoperated atUHF.Thetransmitter powerisrelatively lowandcanbeobtained fromaCW magnetron, abackward-wave oscillator, orareflexklystron, butthesehavebeenreplaced by thesolidstatetransmitter. Thealtimeter canemploy asimplehomodyne 71receiver, butforbettersensitivity and stability thesuperheterodyne istobeprefered whenever itsmorecomplex construction can betolerated. 
 If a short pulse is applied at one end of a series-fed  transmitting array, radiation of energy by the first element might be completed before the  remainder of the energy reaches the last element. On reception, the effect is to smear or distort  the echo pulse. It is possible to compensate for the delay in the series-fed array and avoid  distortion of the main beam when the signal spectrum is wide by the insertion of individual  delay lines of the proper length in series with the radiating elernent~.'~  In a series-fed array containing N phase shifters, the signal suffers the insertion loss of a  single phase shifter N times. 
 In the, usual surveillance radar application, the number of  pulses from any target is limited, hence the operation of an MTI filter is almost always in the  transient state for most recursive filters.16 It has been said that a frequency response character-  istic with steep sides might allow 15 to 30 or more pulses to be generated at the filter output  because of the feedback.14 This might make the system unusable in situations in the presence ^ i .i  of large discrete clutter, and where interference from nearby radars or intentional jamming is  encountered. The poor transient response might also be undesirable in a radar with a step-scan  antenna (as in a phased array), since these extra pulses might have to be gated out after the  beam is moved to a new position, In the step-scan antenna it has been suggested that the  undesirable transient effects can be mitigated by using the initial return from each new beam  position, or an average of the first few returns, to apply initial conditions to the MTI filter for - -  processing the remaining returns from that position.15 The clutter returns can be approxi-  mated by a step-input equal in magnitude to the first return for that beam position so that the  steady-state values that would normally appear in the filter memory elements after an  infinitely long sequence of these inputs can be immediately calculated and loaded into the filter  to suppress the transient response.  Although the undesirable transient effects of a recursive filter can be reduced to some  extent, other approaches to MTI filtering are often desired. 
 C.: Low Jitter High Performance Electronic Range Tracker, IEEE 1975 It~tt~rr~ntior~ill H~iilur  Co~lfrrence, pp. 408-41 1, IEEE Publication 75 CHO 938-1 AES.  58. 
 if the mirror is double-sided. Two target observations per rotation of the mirror are obtained,  'Jut the scanning is not continuous. That is, if the region from Oto 120° is scanned first, the next  region to be scanned is from 240 to 360°, followed by the region from 120 to 240°. 
   WHICH IS USEFUL FOR COM 
 T. Cullen and C. Foss (eds.), Janes Land-Based Air Defence 2001–2002 , Coulsdon, Surrey, UK:  Janes Information Group, 2001, pp. 
 19–26,  January 2002.  5. T. 
 DOUBLE BALANCED TOPOLOGIES COVERING A WIDE RANGE OF 2&  ,/  AND )& FREQUENCIES AND A RANGE OF PER 
 Usually multi-hypothesis tracking10 filters  will be following several hundred GMTs of interest simultaneously. In most cases, all  targets must be tracked and then recognized on the basis of doppler spectrum (helicopters  vs. wheeled vehicles vs. 
 OF 
 The klystron, traveling-wave tube, and the crossed-field amplifier are examples of  microwave power-amplifier tubes. The choice between the power oscillator and the power  amplifier is governed mainly by the particular radar application. Transmitters that employ the  magnetron power-oscillator are usually smaller in physical size than transmitters that employ  the power amplifier. 
 RUNNING  HIGHLY STABLE OSCILLATOR L #OHERENT PROCESSING TO REJECT MAIN 
 The processing is complicated by the fact that  " the number of puls_es to be summed is proportional to the range. Furthermore, the phase  correction in a focused SAR also depends on the range. Adding to the complication of  processing is the large bandwidth and high information content of synthetic-aperture radar. 
 TION TO AN ELEMENT IN AN INFINITE ARRAY (E CONCLUDES THAT  TO  ELEMENTS ARE REQUIRED TO PROVIDE A GOOD INDICATION &IGURE  SHOWS THE CHANGE IN THE MEASURED ACTIVE ELEMENT PATTERN AS THE NUMBER OF ELEMENTS IS INCREASED &OR A  
 //" Ê   Ê, ,Ê-9-/ 
 at tllc Iiigl~er frcqt~ericies tile ~tntetina sidelobe levels can be lower, making it  Illore diliicult for sidelolw jarr~illirig. I lowever, tllc ;~dv:rn tsgcs of oper:tt ing against jarnnlers at  tile Iliglicr frcqt~crlcics arc balariccd in part by the disadvantages of the Iligher fseque~icics,  csljeci;~lly above 1, I>a~ld,.fo~ lorlg-r:~rlgc ail.-sirrveillance radar.  .l.llc ~loisc that crltcrs tlic radar via tiic a~lterlrla sidelobes call be reduced by colic~.c~tt  sidelohe car~celcrs. 
  SHOWN IN &IGURE  B IS AN EXAMPLE OF A HIGHLY VERSATILE ELECTRONIC SCAN  MONOPULSE MISSILE 
    *ULY .   (& /6%2 
 However, in certain cases the receiver which computes the likelihood  ratio is equivalent to a receiver which co~nputes the cross-correlation function or to one with a  matched-filter characteristic, that is, one which maximizes the output signal-to-noise ratio.24  Tile Neyrnan-Pearson Observer is equivalent to examining the likelihood ratio and deter-  rriining if L,(v) 2 K, where K is a real, nonnegative number dependent upon the probability of  false alarm selected.  Interse probability receiver. A detection criterion that has been popular particularly for the  theoretical analysis of statistical detection and for statistical parameter estimation is that  based on irlverse probability. 
 When detection has been accomplished, the search mode is stopped and the tracking mode is initiated by locking a tracking gate onto the tar- get return and thereafter monopulse angle-tracking the antenna about an axis al- ways directed toward the target. The tracking phase ends when rendezvous has been achieved within certain desired terminal accuracy on relative position and velocity. The typical requirements for the STS rendezvous radar are given in Ta- ble 22.1.15 At and immediately following acquisition, the relative velocity vector will gen- erally lie in the direction of the instantaneous line of sight; however, there may be a substantial error equivalent to a relative velocity component perpendicular to the line of sight. 
 This in  effect implemented an automatic gain control (AGC) that selected the most influential  digital samples (bits) from the raw SAR datastream. As designed for Magellan , the  data were digitized into 8 bits, in-phase and quadrature (I&Q). The analog-to-digital  stage was followed by the BAQ operation, which selected the two most significant bits  in each (I&Q) data pair, relative to a mean signal level that had been established from  the previous burst of received data. 
 #8 
  D" POINTS AND DETERMINED  BY A TWO 
 The beam-steering phase is indicated by a in the figure. If '1. is  variahle. 
 POLARIZED SIGNAL  WHICH CAUSES THE ANGLE 
 .1. pp. \OJ 111. 
 These topics  are addressed in Section 20.8. Dealing with clutter-limited situations is a vital part  of the radar designer’s task, requiring a detailed understanding of the phenomena  and their distributions. 20.3 FACTORS INFLUENCING   SKYWAVE RADAR DESIGN Principal Differences Between HF and Microwave Radar. 
 The P 0is the imaging result on the reference plane. It has the same range and Doppler from the antenna with target P . However, referring to the geometric model given in Figure 2, target P and P 0has diﬀerent range migration because the height of the reference plane is inconsistent with the actual height of the target P . 
 This range, with an example dynamic of 2x25 dB = 50 dB, is available for the higher  resolution of the angle between both individual directivity patterns, e.g. 2°.  Newer monopulse  Radar devices have these difference curves stored in look -up tables. 
 Kalmyk'ov, 1:'E. Ostrovsky. and A. 
 KM ALONG 
 The larger size of the fast-wave tube means that it can handle larger  power at the higher frequencies. The gyrotron has mainly been of significance for high- power applications at millimeter-wave frequencies. The solid-state transistor amplifier  has been of interest for radar applications. 
 The phase of the signal alternates FIGURE   8. 14 Ambiguity function of a sine-based symmetrical NLFM waveform 0 0 −1−1t/tp f/B WeightingTarget Radial  Velocity (m/s)* Peak TSL (dB)Average   TSL (dB)**Filter Matching  Loss (dB) LFM unweighted    0 −13.32 −36.59 0 LFM unweighted ±300 −13.32 −36.56 0.024 LFM with –33 dB  Taylor weighting   0 −32.43 −49.27 0.843 LFM with –33 dB  Taylor weighting±300 −32.25 −49.25 0.845 Sine-based NLFM   with k = 0.70   0 −32.67 −48.97 0 Sine-based NLFM   with k = 0.70±300 −26.07 −47.99 0.038 *  An S-band radar with 44- µs transmit pulsewidth and 5-MHz bandwidth was used in this comparison.  The doppler shift expressed in Hz is fd = −(2 /l)Vr = −20Vr where  Vr is the radial velocity expressed in  m/s ( Vr > 0 for an out-bound target). 
 The low-angleENVELOPE OF MAXIMUM ERRORSELEVATION ERROR (degrees) . FIG. 20.12 Multipath impact on monopulse; 6 = path difference, (a) Conventional sum-delta monopulse. 
 The predicted values of radar  range are usually optimistic. In some cases the actual range might be only half that predicted.'  Part of this discrepancy is due to the failure of Eq. (2.1) to explicitly include the various losses  that can occur throughout the system or the loss in performance usually experienced when  electronic equipment is operated in the field rather than under laboratory-type conditions. 
 POLARIZED  SO THAT POLARIMETRIC DIVERSITY IS ALSO SUPPORTED BY THIS ARRANGEMENT -ISSION DESIGN INCLUDES SPACECRAFT STEERING TO SUPPORT SQUINTED ASPECTS RELATIVE TO THE REFERENCE SIDE 
 The two go in and out of phase because the difference in their electrical path lengths increases continuously with increasing ka. The undulations become weaker with increasing ka because the creeping wave loses more energy the longer the electrical path traveled around the shadowed side. The log-log plot of Fig. 
 It is important to guarantee, under RGPO, a very high SNR for the target. In fact,  it might happen that the signal produced by the false target overcomes the detection  threshold whereas the one from the true target does not, thus causing an association  error with possible serious consequences in the target’s tracking. Hence, whenever  RGPO is active, a high energy waveform must be selected. 
 Relative to the beam maximum, therefore, the   sidelobes near broadside are increased by approximately 3 dB. 13.3 PLANAR ARRAYS AND BEAM STEERING Planar Arrays.  A planar array is capable of steering the beam in two dimen - sions. 
 CONJUGATED  MIRROR IMAGES 4HE .YQUIST RATE IS THE SIGNALS TWO 
 There are two equivalent methods for viewing this limitation. From  the frequency domain point of view, each spectral component of frequency corresponds to a  different pointing direction. If the signal contains widely spaced frequency components the  beam will be spread over a considerable angular region rather than confined to a beamwidth  as determined from diffraction theory. 
 The 18 channels are processed  separately through 18 receivers, finally feeding the STAP subsystem with 18-digital  baseband signals. The radar performs platform motion compensation electronically as part of the  STAP architecture. The radar implements an element-space pre-doppler STAP archi - tecture. 
 R. M.: Per f'ormance of a Water-Repellent Radome Coating in an Airport Surveillance  Radar. !'roe. 
 DEFINED DIURNAL AND GEOGRAPHICAL DISTRIBUTION SPECIFIC TO ANY GIVEN RADAR SITE  BUT THEY CAN CAUSE PROBLEMS OVER A WIDE RANGE EXTENT BECAUSE THEY CAN BE ILLUMINATED BY A VARIETY OF PROPAGATION MODES   AS SHOWN SCHEMATICALLY IN  &IGURE  .ORMAL INCIDENCE AS SHOWN YIELDS THE LARGEST ECHO  BUT OBLIQUE INCIDENCE ECHOES AND SCATTERING FROM THE METEOR hHEADv ARE ALSO OBSERVED &IGURE  COMPARES A SIMPLE PREDICTIVE MODEL WITH MEASUREMENTS  CONFIRMING THAT THE OBSERVED BEHAVIOR IS UNDERSTOOD AND THUS CAN BE TAKEN INTO ACCOUNT IN RADAR DESIGN AND OPERATIONS.   (& /6%2 
 It is not possible for us here to go into the  general questions of receiver design, and for the purpose  of discussing radar technique we must assume at this  stage a general knowledge of broadcast reception tech-  nique up to superhet standard. A superhet is essential  for most radar use, and it can be given narrow band-  width by locating band-width controls in the imter-  mediate-frequency (IF) stages. Many radar receivers  working above wavelengths of 10 centimetres have  several HF stages at signal frequency, but for radar  . 
 The model for these angles is  σ θ θ θ θdB00 10 ( ,) ( ) ( ) , f M N f = + = ° ° (16.24 b) The frequency responses below 6 GHz differed for the two years, so the mod - els have separate values of the constants for 1975 and 1976. The year 1976 was  very dry in Kansas: therefore, the 1975 values are probably more representative,  but both are given here. Values of the constants are in Table 16.2. 
 The vacuum  tube is not usually competitive for this application. In Chapter 5, “Multifunctional Radar  Systems for Fighter Aircraft,” the active aperture radar is called an Active Electronically  Scanned Antenna  (AESA). The subsection entitled “Active Electronic Scanned Array  (AESA)” (in Section 5.1) describes quite well the military airborne application of solid- state radar, and enumerates its advantages and why it is important. 
 1 This is a  plot of the mean cross section per unit area, a0, as a function of grazing angle for various  frequencies and polarizations. It does not correspond to any particular set of experimental  l l •1 ,  data, but it represents what might be typical of" average" conditions. It was derived from a  body of data that extended from JO: to 20-knot wind speeds. 
 GATION AND REFLECTION  MUST BE CAREFULLY TAKEN INTO ACCOUNT IN ATTEMPTING TO CLASSIFY  TARGETS EVEN AFTER IMAGE PROCESSING &OR EXAMPLE  THE DEPTH IMAGE OF A VOID IS ALWAYS  APPARENTLY SMALLER THAN ITS PHYSICAL SIZE CORNER REFLECTORS OF ANY REASONABLE SIZE GEN 
 4.2 Why Pulsed?  .....................................................  4.3 . This page has been reformatted by Knovel to provide easier navigation. 
 Nessmith, and S. M. Sherman: Monopulse Tracking Errors Due to Mi1ltipatl.r. 
 Sowa, “Cross-polarized bistatic clutter  measurements,” Electronics Letters -31(6), pp. 490–491, March 16, 1995. 107. 
 In many  navigational problems they provide a much simpler  solution than pulse radar, but some believe that in their  127  . 128 HOW RADAR WORKS  present state of development continuous-wave methods  have certain disadvantages where long ranges have to be  measured accurately. ‘‘It is possible, for instance,” as  a writer in Nature points out,  for continuous-wave systems to be confused by spurious  readings caused by near-by objects, and these local obstacles  tend to reduce the usefulness of continuous-wave systems,  despite their great accuracy. 
 ATED LEVEL OF LARGE SIGNAL GAIN AT   '(Z FROM A  6 DRAIN SUPPLY VOLTAGE HAVE BEEN  REPORTED  FROM A SINGLE TRANSISTOR CELL %LECTRON MOBILITY IN THE 'A. (%-4 AT SATURATED DRIFT VELOCITIES IS HIGH ENOUGH THAT  HIGH GAIN WITH SIMULTANEOUS HIGH POWER OUTPUT AND HIGH EFFICIENCIES CAN BE ACHIEVED WITH VOLTAGES AS LOW AS  TO  VOLTS 7ITH A 'A. EPITAXIAL LAYER PROCESSED ON A 3I# SUBSTRATE  THE CURRENT STATE 
 VERTICAL DATA    AND PARTICULARLY 4HE /HIO 3TATE 5NIVERSITY   &ROM  TO   THE LARGEST PROGRAM WAS AT THE 5NIVERSITY OF +ANSAS        %XTENSIVE PROGRAMS WERE ALSO IN &RANCE #ENTRE .ATIONAL D%TUDES 3PATIALES   #ENTRE .ATIONAL D%TUDES DES 4£L£COMMUNICATIONS  5NIVERSIT£ 0AUL 3ABATIER    THE  .ETHERLANDS   #ANADA #ENTRE FOR 2EMOTE 3ENSING ##23 ESPECIALLY SEA ICE     AND 3WITZERLAND AND !USTRIA SNOW   -ANY OF THE RESULTS FROM THESE PROGRAMS  APPEAR IN DIGESTS OF THE )NTERNATIONAL 'EOSCIENCE AND 2EMOTE 3ENSING 3YMPOSIA )'!233 )%%% 'EOSCIENCE AND 2EMOTE 3ENSING 3OCIETY  AND JOURNALS SUCH AS )%%% 4RANSACTIONS ON 'EOSCIENCE AND 2EMOTE 3ENSING  AND ON /CEAN %NGINEERING   )NTERNATIONAL  *OURNAL  OF  2EMOTE  3ENSING   2EMOTE  3ENSING  OF  %NVIRONMENT   AND  0HOTOGRAMMETRIC %NGINEERING AND 2EMOTE 3ENSING !LTHOUGH CALIBRATIONS FOR SOME OF THE OLDER DATA WERE DOUBTFUL  SUMMARY PRESEN 
 The effect of strong interference [moun- tain clutter, other radar pulses, or electronic countermeasures (ECM)], entering through the sidelobes, will be exaggerated if it exceeds the dynamic range of the LNAs because sidelobes will be degraded. The LNAs are wideband devices, vul- nerable to interference over the entire radar operating band and often outside this band; although off-frequency interference is filtered in subsequent stages of the receiver, strong interference signals can cause clutter echoes in the LNA to be distorted, degrading the effectiveness of doppler filtering and creating false alarms. This phenomenon is difficult to isolate as the cause of false alarms in such radars owing to the nonrepetitive character of many sources of interference. 
 Possibilities also exist for ambiguities in range. The analysis carried out to the point of Eq. (21.37) was not sufficiently general to predict ambiguities in range. 
 848–857, 1995. 11. B. 
 TANK MINE BURIED AT DIFFERENT DEPTHS WITH THE CENTER OF THE MINE SHOWN AS AN OVERLAY 4HESE IMAGES REPRESENT AN UNFOCUSSED REPRESENTATION OF THE TARGET AS A RESULT OF THE $ SPATIAL CONVOLUTION OF THE ANTENNA PATTERN WITH THE TARGET 4HE VARIABILITY OF GROUND CONDITIONS  AS WELL AS THE PHYSICS OF %- WAVE PROPA 
 TWIST REFLECTOR AND A SUBREFLECTOR MADE OF PARALLEL WIRES  4HIS TWIST REFLECTOR DESIGN ENABLES A  ROTATION  OF THE POLARIZATION SUCH THAT THE POLARIZATION OF THE BEAM UPON REFLECTION FROM THE MAIN REFLECTOR IS ORTHOGONAL AND TRANSPARENT TO THE GRIDDED SUBREFLECTOR "LOCKAGE CAN ALSO BE ELIMINATED BY OFFSETTING BOTH THE FEED AND THE SUBREFLECTOR  &IGURE C  7ITH BLOCKAGE AND SUPPORTING STRUTS AND SPILLOVER VIRTUALLY  ELIMI 
  TO  
 The alternative is almost  always limited to traveling wave tube amplifiers (TWTAs), although recent developments  in high-power solid-state devices is influencing SBR SAR design. Radars built around  TWTAs have established impressive longevity records, witness RADARSA T-1 and   ERS-2, both of which remained in operation for more than ten years.FIGURE 18.5  Example of artifacts as they appeared in early RADARSAT-1 four  sub-swath ScanSAR imagery. The direction of flight is vertical in this presentation,  near-edge range at the left of the frame. 
 consists of two sidebands on either side of the carrier plus higher harmonics, a narrowband  filter selects one of the sidebands as the reference signal. The improvement in receiver sensi-  tivity with an intermediate-frequency superheterodyne might be as much as 30 dB over the  simple receiver of Fig. 3.2. 
 (/2):/. 2!$!2   Óä°n£  - ! #ERVERA  $ ! (OLDSWORTH  ) - 2EID  AND - 4SUTSUMI  h4HE METEOR RADAR RESPONSE FUNC 
 power can be extracted from the density-modulated beam. Most higll-  power klystroris for radar application liave one or more cavities between the input and output  R F spoce A F  in Out  El~ctron 1  +I- RF secl~on - I  gun * ~-+-Collec101  I I  i,-igarc 6.9 1)iagranirnatic repruser~tation of the principal parts of a three-cavity klystron.  RADAR TRANSMITTERS 201 Theklystron hasproventobequiteimportant forradarapplication. 
 Peterson, W.W., and T. G. Birdsall: The Theory of Signal Detectability, Univ. 
 Theyshouldbeeasilymanufactured with uniform properties andmusthehomogeneous andisotropic iftheperformance characteristics aretobeindependent ofposition. Theantenna patternofaLuneburg lenshasaslightlynarrower beamwidth thanthatofa paraholoidal rellector ofthesalliecircular crosssection, hutthesidelohe levelisgreater.5660 Thisisduetothefactthatthepathsfollowed bytheraysinaLuneburg lenstendto concentrate energytowardtheedgeoftheaperture. Thismakesitdifficulttoachieveextremely lowsidclobes. 
 Under many non-free-space conditions and with radically non- thermal forms of background noise, the prediction problem is considerably more complicated. Complications not considered in early analyses also result from modification of the signal and noise relationship by the receiving-system circuitry (signal processing). In this chapter the free-space equation will be presented, basic signal process- ing will be discussed, and some of the most important non-free-space environ- ments will be considered. 
  
 Hahn, P. M., and S. D. 
 4 small additional loss is  incurred, however, compare:i to using all the taps to establish the ~hreshold. (For example,  with 32 reference cells, a probability of false alarm, and 0.9 probability of detection, the  392INTRODUCTION TORADAR SYSTEMS theangular location ofthetarget.Thetargetcanbefound,asinbeamsplitting, bytakingthe midpoint between thestartandendofthethreshold crossing. Therewillheahiasintheangle estimate thatdependsonthesignal-to-noise ratio,butthishiascanbeestimated accuratdy. 
 Asaresult ofsuch considera- tions, apower of10to15watts was chosen. This completes the discussion ofthe basic design ofthe system. A few ofthe apparatus details will begiven later but first various points will bediscussed which arenot mentioned inChap. 
 B. G. Laird, “On ambiguity resolution by random phase processing,” in 20th Conf. 
 (The CEA is similar to something called a Klystrode44 except that the CEA  employs the IOT with a multistage depressed collector similar to that used in klys - trons and TWTs.37) In the IOT, the wire grid of a grid-controlled tube is replaced  with an aperture that does not intercept the electrons, and it has a coaxial magnetic  field that confines the electron stream as in a klystron or a TWT. Although an RF  cavity is used in an IOT, the beam is density modulated, or bunched, with a grid  similar to how it is modulated in a triode or tetrode grid-controlled tube. This makes  it smaller and lighter than a comparable klystron. 
 Monitoring Land Subsidence in Wuhan City (China) using the SBAS-InSAR Method with Radarsat-2 Imagery Data. Sensors 2019 ,19, 743. [CrossRef ][PubMed ] 14. 
 TUNABLE RANGES  SWITCHED FILTERS ARE OFTEN REQUIRED&)'52%  &REQUENCY MULTIPLIER OPERATION . 
 The total volume represented by the shaded areas of the ambiguity diagram for  the periodic waveform approximates the total volume of the ambiguity diagram of the single  pulse, assuming that the energy of the two waveforms are the same. This follows from the  relationship expressed by Eq. (11.54). 
 W.: "Radar Reflectivity of Land and Sea," Lexington Books, D. C. Heath and Co.,  Lexington, Mass., 1975. 
 The interconnection density, especially at higher frequencies, can  become a packaging design challenge. At frequencies above 20 GHz, the use of con - ventional connectors is usually prohibitive due to the small width available in full  field-of-view arrays. Manufacturability Considerations  By definition, the use of MMIC components  invokes a microelectronic assembly, test, and handling manufacturing infrastructure. 
 A limita­ tion of the EBS, not found with other semiconductor devices, is that it requires a power supply  of 10 to 15 kV as well as a cathode heater supply.  ,;.  Methods for employing solid-state transmitters. 
 The  specular echoes from singly and doubly curved surfaces (cylindrical and spheroidal  surfaces) are somewhat lower than those from flat surfaces, but are more persistent  with changes in aspect angle. Traveling-wave Echoes.  When the angle of incidence is a small grazing angle off  the surface, a surface traveling wave can be induced. 
 M. A.: Basic Design Considerations: Automatic Navigator AN/APN-67, IRE Trans.,  vol. ANE-4. 
 pp. 215 220, IEEE Cat. no. 
 SION IS DETERMINED BY THE PARAMETERS PECULIAR TO THE PARTICULAR PLANET OR MOON  ABOUT WHICH THE 3!2 IS TO OPERATE 4ABLE   !S A CONSEQUENCE  AN ANTENNA OF AREA  M   AT THE -OON WOULD HAVE BE  M FOR THE SAME RADAR AT -ARS AND NEARLY  M FOR  OPERATION IN %ARTH ORBIT )T ALWAYS IS TEMPTING TO PUSH  THIS CONSTRAINT  SINCE MOST SPACE 
  3!2   THE  3WEDISH .ATIONAL $EFENSE 2ESEARCH %STABLISHMENT #!2!"!3 SENSOR  AND THE 32)  )NTERNATIONAL 5LTRA 
 The usual assumption is that s 0 is constant over the illuminated  area, so that  PP GdA Rrt t= ∫λ σ π2 0 32 44( )Illuminated area (16.17) This assumption would be true only if the antenna confined the radiated energy to  a very small spread of angles and to a fairly homogeneous region. The resulting  expression is  σπ λ03 2 2 44=( ) ∫( ) /P P G R d Ar t t Illuminated area (16.18)FIGURE   16. 13 Typical receiver input-output  curve. 
 Anderson Australian Defence Science and Technology Organisation 20.1 INTRODUCTION Beyond-the-horizon detection of terrestrial targets at ranges of thousands of kilometers  can be achieved by radars operating in the high-frequency (HF) band (3 to 30 MHz). This  very long range coverage is obtained by using skywave  propagation, that is, reflecting  the radar signals from the ionosphere. HF ground wave (surface wave) propagation  over the sea has been used for intermediate but still over-the-horizon distances, up to  several hundred kilometers. 
 Richter: Integrated Refractive Effects Prediction System (IREPS), Naval  Elrginc9crs Jorrrtrnl, vol. 2, pp. 257 262, April. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 5.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 Some modes are used for several operational categories, such as real beam map  (RBM), fixed target track (FTT), doppler beam sharpening (DBS), and synthetic aper - ture radar (SAR), used not only for navigation but also for acquisition and weapon  delivery to fixed targets.38–43 SAR may also be used to detect targets in earthworks or  trenches covered with canvas and a small amount of dirt, which are invisible to EO  or IR sensors. 
 Brown, and J. S. Paterson,  “Polarimetry in radar remote sensing: basic and applied concepts,” in Principles and Applications of  Imaging Radar , F. 
 TRACKING CIRCUITS 4HE DECEP 
 The final tier of output transistors in a serial amplifier chain must be driven into saturation by the preceding stages, and the drive level must be held relatively constant as a function of time and temperature. Since these devices show a narrow operating range, small decreases in the input RF drive level to a multistage amplifier may bring the final tier of devices out of saturation. The net result is an unacceptably degraded output pulse fidelity. 
 Multi-Mission Radar . The Multi-Mission Radar (MMR) is designed to detect and  track mortars, artillery, and rockets. This radar uses a nonlinear FM sine-based wave - form. 
 The outer unit may contain asingle coil that can bemanually oriented, oritmay have two orthogonal coils that can beseparately excited. Ifthe amount of off-centering istoremain fixed, apermanent-magnet arrangement can replace theouter coil. Inthe specific design ofthe coils many factors must beconsidered. 
 SION AVOIDANCE INCLUDE THE NEED TO KNOW A TARGETS  CLOSEST POINT OF APPROACH  #0!   AND TIME TO CLOSEST POINT OF APPROACH 4#0!   BOTH OF WHICH MUST BE AVAILABLE FOR  ALL TRACKED TARGETS 4HE REQUIRED TRACKED TARGET ACCURACY AT  LEVELS IS GIVEN IN 4ABLE  &)'52%     +ELVIN (UGHES 3HARP%YE4- #-2 3 
 TRACK SURFACE SLOPES GRADIENTS  IN THE GEOID MAY BE AS LARGE AS   r n  NEAR THE DEEPER OCEANIC TRENCHES )N SUCH AN EXTREME CASE  A CROSS 
 SECOND OBSERVATION TIME 4HE CORRESPONDING DOPPLER AND DOPPLER RATES ARE ALSO GIVEN IN &IGURE  &OR A SHIP WHOSE PRINCIPAL SCATTERERS ARE LESS THAN  FT ABOVE THE CENTER OF GRAVITY   THE DOPPLERS WILL BE IN THE RANGE OF  o  (Z AT 8 BAND WITH A RATE OF CHANGE OF UP TO   o  (ZS !S LONG AS THE IMAGE RESOLUTION IS NOT TOO GREAT  EACH RANGE 
 Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.556x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 Finally, Figure 2.57 shows the average SCR improvement of the 68 dB Chebyshev  doppler filter bank as well as the optimum curve (from Figure 2.26) as a function  of the relative spectrum spread of the clutter. Owing to the finite number of filters  implemented in the filter bank, the average SCR improvement will change by a small  amount if a doppler shift is introduced into the clutter returns. 
 The caution regarding the drawbacks of a niultifunction radar is especially true of aircraft-  surveillance radar. However, if the particular application is such that the optimum frequency  for search is the same as that for tracking, it is more likely that a tnultifunction array radar  \vnuld have merit over separate radars. Such seems to be the case for satellite surveillance  where the same frequency (UHF) seerris desirable for both search and track, as in the  ANIFPS-85. 
 Along the axis of symmetry of the trihedral reflector in Fig. 11.13 (6 = 0°, <f> = 0°), the RCS is TrfV3X2, where € is the length of one of the edges of the aperture. Not shown are the echo reductions obtained when the trihedral faces are angled other than at 90° from each other. 
 In the Faraday rotator portion, the applied longitu-  dinal magnetic field rotates the circular polarization, imparting the desired phase shift. The  circular polarization is converted to linear by a second nonreciprocal polarizer. A signal  incident from the right is converted to circular polarization of the opposite sense by the  nonreciprocal quarter-wave plate. 
 MENT OF '4$ WHEREIN LOCALIZED '4$ SINGULARITIES ARE CORRECTED 4HE DIFFRACTION TERMS IN 54$ INCREASE THE ACCURACY OF THE BASIC '/ SOLUTION AND WILL PROPERLY PREDICT THE PATTERN ASYMMETRIES OF MORE GENERALIZED REFLECTOR GEOMETRIES ,IKE 0/  '4$54$ METHODS  WILL GENERALLY PROVIDE HIGH 
 59–267, April 1960. 65. P. 
 Time synchronism ismaintained bygenerating trigger pulses ata PRF determined either bythesignal delay line orbyanauxiliary delay line. The methods for doing this can bedivided into two classes regenerative and degenerative. The regenerative method has already been described briefly inSec. 
 The type  of antenna that is used with ultrawideband radar has an important role in defining the  performance of the radar. ch21.indd   24 12/17/07   2:51:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Such a kns is  sometimes called a cm11p11ti11g lens. The beam position of the spherical array was selected by  switching the proper elements of the Lune burg beam-forming lens to the elements or the trans­ mit array. Each of the three Luneburg-lens receive antennas in the radar system could generate a  cluster of three beams pointing in the direction of the transmit beam. 
 APERTURE  PERFORMANCE ASSOCIATED WITH OMNIDIRECTIONAL  OFTEN SHARED  ANTE NNA APERTURES AND LIM 
 BEAM TUBES  THE 2& DRIVE MAY BE WITHHELD DURING THE RISE AND FALL TIME  !LTHOUGH THIS MAY SLIGHTLY REDUCE APPARENT EFFICIENCY  IT  SHOULD BE NOTED THAT ENERGY OUTSIDE THE APPROXIMATELY  S GENERATED DURING RISE AND  FALL WITH THE 2& DRIVE PRESENT IS NOT UTILIZED BY THE RECEIVER ANYWAY )MPROVEMENT BY -EANS OF 3HAPED 0ULSES  3INCE THE ENERGY IN THE SPECTRUM  BEYOND PLUS OR MINUS S FROM  F O IS NOT USED BY THE RECEIVER  IT IS DESIRABLE FOR . 
 ARRAY ANTENNAS THAT ELECTRONICALLY SCAN 4O OBTAIN SIDELOBES AT LEVELS  
 or the  doppler beam-sharpening mode is  (5, = AR  2oT sin U  wlicrc tile synlbols have been defined previously. As II decreases in the doppler bca~n-  sharpening mode. T is made to increase. 
 This can result in a simpler and cheaper phased-array radar  than the conventional array that must scan a wide angle in two orthogonal coordinates.  Although the conventional phased-array radar has not seen extensive application because of  its high cost and complexity, the limited-scan array has had significant application because it is  more competitive in both performance and cost to mechanical scanning antennas. Applica­ tions for limited-scan arrays in radar have included the one-dimensional electronic scan of 3 D  radars (Sec. 
 This is especially important for the low- est beam in the stack, as its main lobe intercepts the earth's surface, admitting surface clutter returns. However, it may also be important for all the beams in the stack, depending on the severity of the clutter. This is so because the elevation patterns of a stacked-beam radar are primarily one-way patterns, being domi- nated by the receiver elevation pattern. 
 XX. Skolnik. M. 
 LENGTH DIFFER 
 Formula (6) can be discretized as: sir(fn,θm)=PQ ∑ l=1gi(l)exp/bracketleftbigg −j4πfn cRi(θm,l)/bracketrightbigg (7) Equation (7) is represented as a matrix considering the effect of noise in actual situations: sir=Aigi+ei, (8) where siis a vector with the size of MN×1, which is formed through signal sampling; Aiis a dictionary matrix with the size of MN×PQ, which is formed through mapping relationship between the target and the signal; giis a vector with the size of PQ×1, which is composed of scene backscatter 156. Sensors 2018 ,18, 3750 coefﬁcients; eiis the additive complex noise in the channel. Speciﬁed composition of each vector and matrix in formula (8) is as follows: sir=[ sir(f1,θ1),···,sir(f1,θM),sir(f2,θ1),···, sir(f2,θM),··· sir(fN,θ1),···,sir(fN,θM)](9) Make: a(fn,θm,l)=exp/bracketleftbigg −j4πfn cRi(θm,l)/bracketrightbigg (10) Following vectors are deﬁned as: a(fn,θm)=[a(fn,θm,1),a(fn,θm,2),···,a(fn,θm,PQ)]T. 
 2018 ,56, 2397–2407. [ CrossRef ] 6. Ruiz-Armenteros, A.M.; Manuel Delgado, J.; Ballesteros-Navarro, B.J.; Lazecky, M.; Bakon, M.; Sousa, J.J. 
 MAX MIN        3! QL  DD CR R    4HE LAST INEQUALITY IS NECESSARY FOR THE CONDITION OF NO RANGE  MIGRATION &OR EXAM 
 BASED 3 
 TIONS OR THE SURFACE 
 Bibby, C. A. Franklin, J. 
 Bulk-effect andavalanche diodes.TheGunnandLSAbulk-effect diodesandtheTrapatt and ImpattQt'Q1Qllche diodescanbeoperated asoscillators orsingle-port negative-resistance amplifiers.29.45Theyhavebeenconsidered foruseatthehighermicrowave frequencies where thetransistor amplifier hasreduced capability, buttheycanalsooperateatLbandorbelow. Unfortunately, thepeakandaverage powersofsuchdevicesarelow,asistheefficiency andthe gain.AnS-bandTrapatt amplifier, forexample. mighthaveapeakpowerof150W,1J..lSpulse width,100Hzpulserepetition frequency, 20percentefficiency, 9dBgain,anda 1dBband­ widthof6.25percent.36.37LSAdiodesmaybecapableofsomewhat greaterpeakpower,but theiraverage powerandefficiency arelow.Theperformance ofthesediodemicrowave sources worsens withincreasing frequency. 
 H. Cantrell, and F. D. 
 When the incident wave is received with a high JNR, an  adaptive array antenna may—in principle—achieve a narrower adaptive beamwidth ,  giving a sharper bearing estimation of the incident wave. If accurate strobes of the jam - mers can be obtained, these can be exploited to form beams in the jammer directions,  which are used as auxiliary channels for adaptive interference suppression.121 The  interference directions can also be used for deterministic nulling, which is of interest  for main-beam nulling.122 In addition to the interference source directions and source  strengths, this technique can provide other information as to the number of sources  and any cross correlations (coherence) between the sources. Such information can be  used to track and catalogue the interference sources in order to properly react to them;  the jammer mapping—a function running in the background—is useful to select the  modes (e.g., admissible pointing directions and waveforms) of multifunction radar  and for general situation awareness. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation. 26.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 FIGURE 26.11  AREPS computations display upon the Composable ForceNet COP ch26.indd   22 12/15/07   4:53:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 123  12.2.1 Introduction ........................................................................................................... 123  12.2.2 Linear and Nonlinear Chirp Waveforms ............................................................... 125  12.2.3 Nonlinear Chirp Based on the Circle -φ Function .................................................. 
 Since little effort had been put upon thejitter problem, itseemed reasonable to expect that triggered gaps can beconsiderably improtied. The rotary gapcanbeused forMTI only ifastorage tube serves asdelay element. 16.15. 
 Sensors 2019 ,19, 2161 (a)( b) Figure 4. TFTPCF curves with different p.(a) TFTPCF versus frequency separation. ( b) TFTPCF versus spatial separation. 
 These tubes are really the two parts of a concentric  transmission line, and the radio-frequency oscillations  are set up at the slits through which the electron beam 1s  directed. The concentric tubes are connected to the  output circuits by a concentric feeder-line, but there is  an alternative form of Heil-tube construction in which  one part of the concentric feeder projects through the  glass tube, and it can be tuned within narrow limits by  an external extension. Theory of the Heil tube is some-  what complicated, but is a parallel with that of the  klystron and Sutton tubes: it has been said that the gap  between the outer tube and the inner is in effect the  ‘yelocity-modulating’ space, the space inside the inner  . 
 WIDE NEED FOR SUCH RADARS 4HIS HAS RESULTED IN THE DEVELOPMENT OF LOW 
 In the limit of small ratios of rms waveheight to  radar wavelength or, more specifically,  2kh  1  (15.15) only the first term in the series in Eq. 15.13 survives, and the cross section assumes  the very simple form  σ ψ π ψ ψ0 4 14 2 ( ) ( ) ( c os)( )= ′k F W kp  (15.16) ch15.indd   28 12/15/07   6:17:14 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 LIKE PULSE SHAPE  A TRUNCATED GAUSSIAN  PERHAPS A COSINE ON A PEDESTAL  OR OTHER TYPE OF NONRECTANGULAR SHAPE 4HE PROBLEM WITH USING CONVENTIONAL TRANSMITTERS SUCH AS DISCUSSED IN THIS CHAPTER IS THAT WHEN USING A SHAPED WAVEFORM SOME LOSS IN EFFICIENCY RESULTS 4HUS   IT IS SELDOM THAT A RADAR DESIGNER WOULD WANT TO USE A HIGHLY SHAPED PULSE WAVEFORM  IN ORDER TO REDUCE THE SPECTRUM RADIATED OUTSIDE OF THE RADARS NORMAL OPERATING SIGNAL BANDWIDTH 4HE #%!  HOWEVER  IS AN 2& POWER SOURCE THAT DOES NOT HAVE ITS EFFICIENCY DECREASED WHEN A NONRECTANGULAR  OR SHAPED  WAVEFORM IS USED 4HE #%! HAS BEEN WIDELY USED FOR COMMERCIAL 46 TRANSMITTERS THAT HAVE HIGHLY MODULATED  NONCONSTANT AMPLITUDE WAVEFORMS 4HE #%! IS BASED ON  A GRID 
 Target bearing isdetermined byreading off the antenna azimuth when theecho signal from the target inquestion appears tobestrongest. The azimuth accuracy depends onproper siting, asinthe case ofallradar making use ofground reflections, and attainable accuracy inpractice isabout +4°. Height-finding can be performed bythe method ofnulls (Sec. 
 CANCELLATION DUE TO THE  RANGE OF THE CLUTTER OF INTERESTREDUCES NOISE AT THE LOW FREQUENCIES BY  D" PER DECADE BELOW THE BREAK FREQUENCY OF  F42     P (ERE 42 C2    IS THE TIME &)'52%  0OWER AMPLIFIER SIMPLIFIED BLOCK DIAGRAM &)'52%  0ULSED OSCILLATOR SIMPLIFIED BLOCK DIAGRAM . Ó°Èn  2!$!2 (!.$"//+  DELAY OF THE CLUTTER RETURN   2 IS THE CLUTTER RANGE   AND C IS THE SPEED OF LIGHT &OR THE  SECOND ADJUSTMENT DUE TO THE  FREQUENCY RESPONSE OF THE CLUTTER FILTERS  WHICH AS STATED  PREVIOUSLY ARE ASSUMED TO BE &)2 CANCELERS WITH BINOMIAL WEIGHTS  IT IS NOTED THAT  THE RESPONSE AT VERY LOW FREQUENCIES FALL OFF AT  D" PER DECADE FOR ONE DELAY   D" PER DECADE FOR TWO DELAYS   D" PER DECADE FOR THREE DELAYS  ETC !S AN EXAMPLE  THE APPROXIMATION USED FOR A TWO 
 The slightly lossy dielectric is changed to a fairly good condlic-  tor with the application of forward bias. The capacitive component of the circuit disappears  and the equivalent circuit becomes a small resistance which decreases in value with increasing  forward current. The resistance can vary from thousands of ohms at zero bias to a fraction of  intrinsic  region  conductrng  Forward state Reverse state  Junction  capacitance  Forward -bias  resistance  ~nductance Figure 8.9 PIN diodes and simplified equivalent Bock -bias  resistance circuits for forward and reverse states. 
 L. Cain. C. 
 IEEETrails.•vol.AP-23.pp.269-271. March. 1975. 
 The ARM  trajectory is usually selected to attack the radar through the zenith hole region above  the radar, where its detection capability is minimal. Thus, a supplemental radar that  provides a high probability of detection in the zenith hole region is required. There are  certain advantages in choosing a low transmitting frequency (UHF or VHF) for the  supplemental radar. 
 In such situations  the target echo must compete with the clutter energy for recognition. A large part of the clutter  energy may be removed with a bank of fixed narrowband filters covering the expected range of  doppler frequencies. The bandwidth of each individual filter must be wide eno~~gh to accept  the energy contained in the target echo signal. 
 ING ELEMENTS  AND THE COMMON PRACTICE WITH (& RADAR IS TO DRIVE EACH ELEMENT WITH A SEPARATE AMPLIFIER  4HIS APPROACH PERMITS BEAM STEERING AT A LOW POWER LEVEL IN THE  AMPLIFIER CHAIN 4HE ACTIVE ELEMENT IN EACH FINAL TRANSMITTER STAGE CAN BE EITHER A TRA 
 VIEW OF ALL ASPECTS OF WEATHER RADAR 4HE )%%% 'EOSCIENCE AND % LECTRONICS  3PECIAL )SSUE  ON 2ADAR -ETEOROLOGY  !TLASS 2ADAR IN -ETEOROLOGY  7AKIMOTO AND 3RIVASTIVAS  2ADAR AND !TMOSPHERIC 3CIENCE ! #OLLECTION OF %SSAYS IN (ONOR OF $AVID !TLAS  AND . 
 VI than on ASV Mk. III. This required more careful use of the gain control during searching. 
 Goldie, H.: What's New With Receiver Protectors?, Microwaves, vol. 15, pp. 44-52, January, 1976. 
   PP n  3EPTEMBER   h(ANDBOOK FOR .!630!352 3YSTEM /RIENTATION v VOL   .AVAL 3PACE 3URVEILLANCE 3YSTEM   $AHLGREN  6!  *ULY     - ) 3KOLNIK  h!N ANALYSIS OF BISTATIC RADAR v )2% 4RANS  VOL !.% 
 One is a frequency- domain explanation. This is Doppler Beam Sharpening. If one prefers, one can ana - lyze the system in the time domain instead. 
 EXPANSION FACTOR OF  @ 2@   @ 2   FOR THE COMPRESSED PULSE !S FOR THE CASE OF EQUAL ,&- SLOPES  THE RANGE WINDOW  WIDTH DEPENDS ON THE ACHIEVABLE PROCESSING BANDWIDTH 3TRETCH 0ROCESSING 2ANGE 2ESOLUTION 7IDTH  4HE  
 Simulated SAR images under different wind speeds. ( a–c) correspond to wind speeds of 4 m/s, 7 m/s, and 10 m/s respectively. The red arrow represents the wind direction, the black arrow represents the radar look direction, and the blue arrow indicates the rotation direction of the current ﬁeld. 
 Energy Definitions. For detection of radar echoes against a noise back- ground, the only fundamental parameters are the energy content of the transmit- ted signal, of the receiver noise, and of the echoes received as the antenna scans past the target. These energy parameters define the width of a rectangular func- tion that has the same peak response and same energy content as the real func- tion. 
 ................................ ................................ ................. 
 BAND RADAR 4HE 8 
 An operator viewing a PP! would have no problem. However, in a flexible phased-array  radar. the scanning of the heam positions might not be uniform. 
 The locations along the frequency  axis where the straight lines intersect are called break frequencies.  This simplified  procedure, which is similar to that presented in Vigneri et al.,40 is described in the  following paragraphs. The first of the three adjustments—oscillator noise self-cancellation due to the  range of the clutter of interest—reduces noise at the low frequencies by 20 dB per  decade below the break frequency of f TR = ⋅ ⋅ 1 2/( )π. 
 9.)NO FADING Pfa = 1(T6PROBABILITY OF FALSE ALARMPROBABILITY OF DETECTION . SINGLE-PULSE SIGNAL-TO-NOISE RATIO IN dB FIG. 8.6 Angular accuracy obtained with beam-splitting estimation procedure for the no-fading case. 
 The operations shelter isthe heart ofthe system. Itsinterior is shown inmore detail inFig. 7“12. 
 933-936, June 1987. 18. Howe, H.: "Stripline Circuit Design," Artech House, Norwood, Mass., 1974, pp. 
 itispossible tomodifytheantenna patterntoradiatemoreenergyathigherangles. Onetechnique foraccomplishing thisistoemployafanbeamwithashapeproportional tothe squareofthecosecant oftheelevation angle.Inthecosecant-squared antenna (Sec.7.7),the gainasafunction ofelevation angleisgivenby for1>0<1><1>m (2.46) whereG(<p)=gainatelevation angle1>.and1>0and1>maretheangular limitsbetween whichthe beamfollowsacsc2shape.Thisappliestotheairborne searchradarobserving groundtargets aswellasground-based radarsobserving aircrafttargets.(Intheairborne case,theangle1>isthe depression angle.)From1>=0to1>=<Po.theantenna patternissimilartoanormalantenna pattern. butfrom1>=1>0to1>=1>m,theantenna gainvariesascsc21>.Ideally,theupperlimit 4>mshouldhe90°.butitisalwayslessthanthiswithasingleantenna because ofpractical difficulties. 
 The two uncertainty principles apply to different phenomena,  and the radar principle based on classical concepts shoulcf'not be confused with the physics  principle that describes quantum-mechanical effects. In classical radar there is no theoretical  limit to the minimum value of the {)TR bf product since the radar systems designer is free to  choose as large a pa product (by proper selection of the waveform) and E/N0 ratio as he  desires, or can afford. His limits are practical ones, such as power limitations or the inability to  meet tolerances. 
 Thepredicted position atthen+1stscanisxn+xnTs.(Whenaccelera­ tionisimportant athirdequation can be addedtodescribe anex.-fJ-ytracker, where y=acceleration smoothing parameter.)73 Forex.=fJ=0,thetrackerusesnocurrentinforma­ tion,onlythesmoothed dataofpriorobservations. Ifex=fJ=I,nosmoothing isincluded atall. Theclassical ex.-fJfilterisdesigned tominimize themeansquareerrorinthesmoothed (filtered). 
 {. CHAPTER  THIRTEEN  RADAR CLUTTER  13.1 INTRODUCTION TO RADAR CLUTI'ER  Clutter may be defined as any unwanted radar echo. Its name is descriptive of the fact that  such echoes can "clutter" the radar output and make difficult the detection of wanted targets. 
 159.pp2742Xll.Jan.19.196X. 92.Houghton. F.W.F.Blackwell.andT.A.Wilmot: BirdStrikeandtheRadarProperties ofBirds. 
 Thelensarrayallowsmorefreedom thanthereRectarray indesigning thefeedassembly sincethereisnoaperture blocking, butthebacksurfaceofthereRectarray makesiteasierto providethephaseshiftercontrolanddriveassemblies, structural members, andheatremoval. Space-fed arraysaregenerally cheaperthanconventional arraysbecauseoftheomission of thetransmission-line feednetworks andtheuseofasingletransmitter andreceiverratherthan adistributed transmitter andreceiverateachelement. Aspace-fed arraymaybesimplerthan anarraywithaconstrained feed,butasacrifice ismadeinthecontroloftheaperture illumination~'and inthemaximum powercapability ofthearray.Thustheabilitytoradiate largepowerbyusingatransmitter ateachelement islostinthisconfiguration. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Radar Transmitter.  THE RADAR TRANSMITTER  10.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 in radar. 
 I, Can. J. Phys. 
 (a) ( b)     (c) ( d)  Figure 5. Image and image with ﬂipping, brightening, and sharpness. ( a) An original image. 
 U. Nickel, “Performance of corrected adaptive monopulse estimation,” IEE Proc ., vol. 146,   pt. 
 .OISE !MPLFIIERS    -ULTIPLE STAGE LINEAR DESIGNS REQUIRE PROPER DEVICE  SIZING OF SUCCESSIVE STAGES IN ORDER TO MAINTAIN LOW INTERMODULATION DISTORTION PRODUCTS   #IRCUIT LOSSES ON THE INPUT  BEFORE THE FIRST STAGE  DEGRADE THE NOISE FIGURE OF THE DESIGN THEREFORE  SOME DESIGNS UTILIZE OFF 
 In the mid-1980s, the ASR-9 air surveillance  radar at S band was developed by Northrop Grumman (then Westinghouse) for use  at major airports to control local air traffic.54 It was an excellent radar that used a  ch10.indd   27 12/17/07   2:19:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. The Radar Transmitter. 
 The remaining. SEC. 3.16] CITIES 105 four signals represent thetowns ofGardner, Fitchburg, Leominster, and Ayer. 
 Radar MeteoroL, pp. 251-256, American Meteorological Society, Boston, 1984. 61. 
 VERSUS 
 99. Bachman, C. G.: "Radar Targets," Lexington Books, Lexington, Mass., 1982, p. 
 NARIO IS OBSERVED BY THE RADAR AT TIME  T K THE RADAR MODEL PROVIDES THE MEASUREMENTS  RK  BK  EK AND 3.2K 4HE TRACKING FILTER UPDATES THE PREVIOUS TARGET STATE ESTIMATE  8K 
 ING WITH REDUNDANT RECEIVE CHANNELS WITH RECEIVER 
 16.24 a. ch16.indd   32 12/19/07   4:56:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 BEAM KLYSTRON IS THE EFFICIENT GENERATION OF  HIGH 2& POWER AT A LOWER VOLTAGE THAN IN A CONVENTIONAL KLYSTRON "ECAUSE OF ITS LOWER  VOLTAGE TWO OR THREE TIMES LOWER   AN -"+ CAN BE MORE COMPACT  HAVE A LOWER MAGNET WEIGHT UP TO TEN TIMES LESS   BE OF LOWER WEIGHT AND VOLUME  GENERATE LESS 8 
 TION  WHERE  @ IS A VARIABLE AND THE  TARGET SPAN IS FROM   , TO n,  CALCULATION OF THE  RADIUS OF GYRATION DIVIDED BY  GIVES A VALUE OF  RANG OF , 4YPICAL VALUES OF  RANG  ON ACTUAL AIRCRAFT FALL BETWEEN  , AND ,  DEPENDING UPON THE  DISTRIBUTION OF THE  MAJOR REFLECTING AREAS SUCH AS ENGINES  WING TANKS  AND SO ON ! SMALL AIRCRAFT  NOSE 
  AND AMPLITUDE 
 13.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 Effect of Errors.  When errors occur in phase or amplitude, energy is removed  from the main beam and distributed to the sidelobes. If the errors are purely random,  they create random sidelobes that are considered to be radiated with the gain and  pattern of the element. 
 Lincoln Laboratory35 in its moving-target detector (MTD) used a clutter map for the zero-doppler filter very effectively. The decision threshold T for the ith cell is T = A S1-I (8.22) where 5. = K S1-., + AT1- (8.23) S1 is the average background level, Xt is the return in the /th cell, K is the feed- back value which determines the map time constant, and A is the constant which determines the false-alarm rate. 
 Zissis (eds.), The Infrared Handbook , rev. ed., Ann Arbor, MI: Environmental  Research Institute of Michigan (now General Dynamics, Ypsilanti, MI), 1989. 24. 
 Kanberoglu, B.; Frakes, D. Extraction of Advanced Geospatial Intelligence (AGI) from Commercial Synthetic Aperture Radar Imagery. In Proceedings of the Algorithms for Synthetic Aperture Radar Imagery XXIV 2017, Anaheim, CA, USA, 9–13 April 2017; Volume 10201, p. 
 The difference between the reflected  path AMB and the direct path AB (or A"MB) is i\ = 2ha sin~. when R ~ha.For~ small, sin~  may be replaced by (ha + h,)/ R so tha~ 'i\ = 2ha(ha + h,)/ R :::::: 21za h, / R. The latter expression  Figure 12.1 Propagation over a plane reflecting surface. 
 Independent Samples Required for Measurement Accuracy.  The Rayleigh  distribution describes the fading signal fairly well. If we assume a Rayleigh distribution  of fading, the number of independent samples required for a given accuracy is shown in  Figure 16.16. 
 KNOWN TRADEOFFS AMONG GAIN  BEAMWIDTH  AND SIDELOBE LEVEL  )N ORDER TO KEEP THE BEAMWIDTH SMALL WITH LOW SIDELOBES  A LARGER  AND COSTLY THE COST COULD NOT BE THAT LARGE UNLESS THE RADAR USES AN ACTIVE APERTURE  ANTENNA IS NEEDED 4HE CHIEF PROBLEM WITH THE LOW SIDELOBE ANTENNA IN ITS EARLY DAYS WAS THAT IT HAD MORE MECHANICAL PROBLEMS BECAUSE IT WAS A WAVEGUIDE ARRAY AND NOT A REFLECTOR /THER DESIGN PRINCIPLES INVOLVED IN LOW ANTENNA SIDELOBES ARE THE USE OF RADAR 
 —Whenever one ofthe relay stations isinan aircraft, especially ifthe transmission path isover water, interference -80 -1oo. II; ,,. -110I/ ,. 
 RADAR RECEIVERS  6.376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 For IF sampling, a frequency at least twice the IF bandwidth is required; however,  oversampling is typically employed to ease alias rejection filtering and to reduce the  effect of A/D converter quantization noise. IF sampling is often performed with the  signal located in the second Nyquist region, as shown in Figure 6.15 or in higher  Nyquist regions. Stated Resolution. 
 AES-4, pp. 402-409,  May, 1968.  52. 
 10.10~ is equivalent to an  exponential weighting of the received pulses. It results in a loss of about 1.0 dB in signal-to-  noise ratio as compared with the ideal postdetection integrator that weights the received pulses  in direct proportion to the fourth power of the antenna beam pattern.66 It is 0.5 dB less  efficient than the moving window detector with uniform weights.67 The double-loop integrator  of Fig. 10. 
 This can result in relatively long  dwell times, and it is possible for the savings obtained with the Sequential Observer to be  negated. Th~ required dwell time might be even longer than that of the fixed sample-number  Neyman-Pearson Observer.  If the Sequential Observer allows a savings in average power of from 8 to 10 dB when  implemented for a single-range cell, the power advantage decreases to 3 to 4 dB for 200-range  cells and can even be as little as 1 dB.40 In addition, th~ Sequential Observer requires some­ thing more flexible than the usual rotating-antenna radar. 
 BAND AND OUT 
 C. Keller, W. J. 
 Although gyro-oscillators have been capable of greater power than gyro-amplifiers,  the gyro-amplifier has usually been preferred for radar applications for the same rea - son the amplifier has been preferred at microwave frequencies, especially when dop - pler processing is important. An example of a high power gyroklystron for radar applications is the VGB- 819434,35 that was used in the experimental W-band radar known as Warloc  at the U.S.  Naval Research Laboratory. 
 Layton. and P. K. 
 FM-CW altimeter. 86-87  Flicker noise, 74, 347-348  Fluid-cooled helix TWT. 207  Flux drive ferrite phase shifter. 
 Open ocean measurements at Ku band and at much higher  grazing angles72 show sufficient variability with wind speed, rain rate, and grazing  angle to leave the uncertainties that opened this section largely unresolved. In addition to scattering from the raindrop impacts, the distribution of raindrops  in the volume of the atmosphere above the surface can have two additional effects  on sea clutter—as an absorber/scatterer over the radar propagation path, which is  well-understood, and as a mass-additive to the wind, affecting momentum transfer  to the surface and thus the excitation of wind waves themselves, which is less  well-understood.73 Atmospheric Ducting.  Another topic in sea clutter that has been little explored  is the role played by propagation effects  within the atmospheric boundary layer  lying over the sea surface. 
 19. H. Sakamoto and P. 
 'RUMMAN #ORPORATION.   39.4(%4)# !0%2452% 2!$!2   £Ç°Óx 'UARINO AND )BSEN DESCRIBE AN EXPERIMENT USING THE !.!0' 
 These letter descriptions of radar displays date back to World War 11. They are  not all in current usage; however, the PPI, A-scope, B-scope, and RHI are among the more  usual displays employed in radar. There are also other types of modern radar displays not  included in the above listing which have not been given special letter designations. 
   APPROVED FOR PUBLIC RELEASE  # +OPP h4HE PROPERTIES OF HIGH CAPACITY MICROWAVE AIRBORNE AD HOC NETWORKS v 0H$    DISSERTATION  -ONASH 5NIVERSITY  -ELBOURNE  !USTRALIA  /CTOBER   *  +ATZMAN   $EFENCE  )NDUSTRY  $AILY   HTTPWWWDEFENSEINDUSTRYDAILYCOMELEC 
 DIMENSIONAL REGION '  THEN   %;.&4=   K& r K¼P- 
 ELEMENT ARRAY u 2ECEIVER AND PLANE WAVE REJECTION TESTS APPLIED TO INJECTED BROADBAND NOISE   4HIS APPROACH PROVIDES USEFUL METRICS OF CALIBRATION PERFORMANCE AND RELATIVE PERFORMANCE  BUT DOES SO ONLY DOWNSTREAM FROM THE RECEIVER INPUTS  AS WITH II  ABOVE.   (& /6%2 
 TO 
 D. Burnside, “Expansion of existing EM Workbench for multiple  computational electromagnetics codes,” IEEE Antennas and Propagation Magazine , vol. 45,  no. 
 CONTROLLED VACUUM TUBE COULD BE OPERATED AS EITHER AN OSCIL 
 3TATE 4RANSMITTERSv "RIEFLY  PROPONENTS OF SOLID STATE MIGHT S AY THAT THEY DO NOT NEED  A HOT CATHODE AS DOES A VACUUM TUBE  DO NOT REQUIRE HIGH VOLTAGES OR MAGNETS  DO NOT PRODUCE 8 
 METEOR SOURCES v  %ARTH  -OON AND 0LANETS  VOL   PP n 
 SHIELDING EFFECTS TO ESCAPE RADAR DETECTION )N THIS CASE  THE SELECTION OF WAVEFORM AND FREQUENCY IS MADE TO TACKLE THE PROBLEMS OF MASKING  MULTIPATH  CHAFF  CLUTTER  AND %#-    4HE MAJOR %7 THREATS TO A SURVEILLANCE RADAR ARE I  NOISE JAMMING  II  CHAFF    III  DECEPTION JAMMING  IV  DECOYS AND EXPENDABLES  AND V  !2- #OMMON TYPES OF JAMMING ARE MAIN 
 D. Lynch et al., “Advanced avionics technology,” Evolving Technology Institute Short Course  Notes, November 1994. 10. 
 1956. 45.Monaghan. S.R..andM.C.Mohr:Polarization Insensitive PhaseShinerforUseinPhasedArray Antennas. 
 It is capable of 3 MW of peak power over a 300 MHz bandwidth, with ti  0.002 duty cycle, a 2-ps pulse width, and a gain of 33 dB. This tiibe is similar in many respects  to the VA-87 klystron amplifier. It was originally designed to be used interchangeably with thc  VA-87 klystron, except that the VA-125 TWT has a broader bandwidth and requires a larger  input power because of its lower gain. 
 MODULATED SIGNAL  AT THE SCANNING OR LOBING RATE  WHICH IS SIGNIFICANTLY OUT OF PHASE WITH THAT FROM THE TARGET RETURN 7HEN THE CONICAL 
 80, no. 1, pp. 152–161,  January 1992. 
 100.Plank,V.G.:AMeteorological StudyofRadarAngels.U.S.A.F. Camhridge Research CellterGeoph}'s. Research Papers.no.52.July;1956.AFCRC-TR-56-21 l.AD98752. 
 4  Therefore, the results previously derived for a gaussian clutter spectrum can be readily applied. 9  Equations 4.25 and 4.26 derived for the clutter fluctuation improvement factor apply for the  antenna scanning fluctuations by proper interpretation of a,, the standard deviation, or the  rms spread of the frequency spectrum about the mean.  The voltage waveform of the received signal is modulated by the square of the antenna  electric-field-strength-pattern, which is equal to the (one-way) antenna power pattern C;(f)),  described by the gaussian function as  Since the antenna is scanning at a rate of 0, deg/s the time waveform may be found from  Eq. 
 This is a logarithmic receiver in which the slope of the logarithmic characteristic  progressively declines by a factor of 2 to 1 over the range from noise level to + 80 d~.~"~'  (This assumes that the normal log-FTC has a logaritl~mic characteristic from - 20 dB below  the receiver noise to + 80 dB above noise.) In the log-log receiver the higher clutter values  (tails of the distribution) are subjected to greater suppression.  Adaptive video threshold. Other receiver techniques than the log-FTC were discussed in  Sec. 
 NOISE RATIO  IT IS IMPORTANT TO SPECIFY WHETHER THE NOISE LEVEL BEING REFERENCED IS THE RECEIVER NOISE OR TOTAL SYSTEM NOISE -INIMUM 3IGNAL OF )NTEREST  -INIMUM SIGNAL DEFINITIONS SUCH AS MINIMUM 
 1, p. 300, January 2002, correspondence. 120. 
 MlT Researcll Lab. Electror~ics Trch. Rept. 
 Wait, “Propagation of electromagnetic pulses in a homogeneous conducting earth,” Appl.  Sci. Res. 
 Anderson, J. Praschifka, and I. M. 
 SYNCHRONOUS ORBIT AND SINCE THE ANTENNA PATTERN TO FIRST ORDER  IS SYMMETRIC  THE SPACECRAFT MAY BE ROTATED ABOUT THE RADARS LINE 
 CALLED WIDE BANDGAP SEMICONDUCTORS 7"'3  4HE LATTER ARE DOMINATED BY THE SILICON CARBIDE 3I#  -%3&%4 AND THE GALLIUM NITRIDE !L'A.'A.  HETEROJUNCTION FIELD EFFECT TRANSISTOR (&%4  4HE ADVENT OF THE THIRD SEMICONDUCTOR GENERATION OPENS ENORMOUS NEW POSSIBILITIES IN THE AREA OF HIGH POWER AMPLIFIERS FOR USE IN SOLID 
 Accurate measurements depend on compensation for any difference in gains of the monopulse receivers. Readers interested in the methods of generating the analog STC waveforms used in older radars may find descriptions of various methods in Sec. 5.6 of the 1970 edition of this handbook. 
 TO 
 FIELD ANTENNAS  AND  2& SAMPLING -UTUAL 
 For this delta beam illumination function, the normalized boresight monopulse sensitivity is TT/ 2 * 1.57. The sensitivity degrades off boresight, despite an increasing monopulse ratio slope, owing to a decreasing signal-to-noise ratio in the two channels and toContinuous aperture WA = wA(jt) aperture illumination W2 = Vv2U) functions llwAll = (f*x\w*(x)\2dx)l/2 ay \ 1/2 "x |w2U)|2</r/ A(6)= fX wAU) exp (flirx (sin 6))rfr/llwAH J -OC 2(6)= I W2U) exp (y2irjc(sin6)£/jc/llw2ll J — XDiscrete aperture array WA = (WA/I) w=l, N vectors of WV = (w2J array weights (» \ ""•All=\E|H'A,,2J"2 x 1 '11^n = (EKJ2V2\ 1 / N A(0) = 2H'A» exp [j2iTJcw(sin 6)]/l!wAH i N 2(8) = ]£w2,, exp [./^(sin 0)]/llw2lli . *fl = RMSEo RMSc ; = accuracy with Taylor I, Bayliss A; RMSE0 - accuracy with uniform I, linear-odd A. 
 Air-supported radomes can be folded  i~tto a srnall package wtiicli make them suitable for transportable radars requiring mobility  and quick erectiori times. Typically, a 50-ft radome can be installed at a prepared site in about  one or two hoirrs.'" They are also of interest on static sites where wideband frequency  operatio11 is desired. One of tlie largest examples of an air-supported radome was the 210 ft  diameter radonie for the Bell Telephone System Telstar satellite communication antenna at  Andover. 
 4(% 
 Oneofthelimitations ofasimpleunswitched nohscanning pencil-beam antenna isthat theangleaccuracy canbenobetterthanthesizeoftheantenna beamwidth. Animportant featureofsequential tobing(aswellastheothertracking techniques tobediscussed) isthatthe target-position accuracy canbefarbetterthanthatgivenbytheantenna beamwidth. The accuracy depends onhowwellequality ofthesignalsintheswitched positions canbe determined. 
 105, pp. 408-413.  24. 
 HOP % 
 There is another ractor which reduces the right-hand side of Eqs. (14.10) or (14.l lb) when  optical processing or similar processing is used. As will be explained later, this increases the  right-hand side of Eq. 
 The name of this organisation was changed to theTelecommunications Research Establishment (TRE) in November 1940. In May 1942, TRE moved to Malvern, because of the danger of commando raids and vulnerability to bombing on the south coast of England. The ﬁrst centimetric radar developments were aimed at air interception (AI) radar for ﬁghter aircraft. 
 17. J. Davis, “Sun intros eight–core processor,” Electronic News , Reed Elsevier, November 14, 2005. 
 Processing.  Although similar in principle to airborne systems, processing for  space-based SARs differs in several key regards. The highlights are reviewed here. 
 HAND SIDE OF THE EQUATION CORRESPONDS TO THE UPPER  SIDEBAND AND THE SECOND TO THE LOWER SIDEBAND AT THE MIXER OUTPUT 4HE UPPER SIDEBAND IS REJECTED BY THE BANDPASS FILTER TO YIELD  XT !T 4T 42 2)&RECT RECT  COS; 
 The sum signal uses only the center  two horns to limit its E field in the E-plane as desired for the ideal field shaping.   FIGURE   9.5  Twelve-horn feed ch09.indd   7 12/15/07   6:07:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Spencer, C. Wu, and D. G. 
 IEEE T rans. Geosci. Remote Sens. 
 (a)  Rodar  ~ 69  (bl P, GA,.ac C = ---------(4rr)2 R4  Clutter  0 0 0 0  0 0  0  0 0 0  0  0 0 0 0  0  R68 ( 13.3)  0 0  0 0  0 0 0  0 0 0 0  0  Figure lJ.I Geometry or radar clutter. (a) Elevation view showing the extent of the surface intercepted by  the radar pulse, (b) plan view showing clutter patch consisting of individual, independent scatterers. 472 INTRODUCTION TO RADAR SYSTEMS  where P, = transmitter power  G = antenna gain  Ae = antenna effective aperture  R = range  <J, = clutter cross-section, which is equal fO  <Ic= a0Ac= a0ROB(cr/2)sec <P ( 13.4)  where c = velocity of propagation. 
 SIGHT RELATIVE TO THE PLATFORMS VELOCITY VECTOR 4HIS PROCESS IS KNOWN AS  CLUTTER  POSITIONING /UTPUT 'ENERATOR  4HE OUTPUT GENERATES THE PULSED RADIO FREQUENCY 2&  TRANSMIT  SIGNAL  WHICH IS THE TRANSMIT DRIVE SIGNAL THAT IS AMPLIFIED BY THE POWER AMPLIFIER PRIOR TO BEING FED TO THE TRANSMIT ANTENNA !NTENNA 4HE ANTENNA CAN BE MECHANICALLY OR ELECTRONICALLY SCANNED -ODERN  PULSE DOPPLER RADARS HAVE MIGRATED TO THE USE OF ACTIVE ELECTRONICALLY SCANNED ARRAYS !%3!S   !%3!S CONTAIN TRANSMITRECEIVE  42  MODULES  EACH COMPRISING A TRANS 
 Landclutterhasbeenmodeled asaLambert surfacewith(10varying assin2cjJ,where cjJ=grazing angle55;asassemblies ofspheres, hemispheres, hemicylinders55,56;asspecular renection fromsmallnat-plate segments, orfacets,whichbackscatter radarenergyonlywhen thefacetsareoriented perpendicular totheradarlineofsight57;asaslightly roughsurface (similar tothemodelusedtodescribe seaclutter)todescribe scattering fromconcrete and asphalt 40;asanapplication oftheKirchhoff· Huygens principle whichmakestheassumption thatthecurrent flowingateachpointinalocallycurvedsurfaceisthesameaswouldflowin thesurfaceifitwerenatandoriented tangenttotheactualsurface58;andasamodelconsist­ ingoflong,thin,lossycylinders randomly distributed todescribe certaintypesofvegetation suchasgrass,weeds,andnags.40Noneofthesehavebeentoosuccessful asageneralmodel; however, theydoprovidesomeguidance fortheunderstanding ofspecificlandclutter. 35 13.6DETECTION OFTARGETS INLANDCLUTIER Manyofthetechniques discussed inSec.13.4forthedetection oftargetsinseaclutterhave application forlandclutteraswell.MTIandhighresolution aretwoimportant examples. High-resolution resultsinaprobability density function thatisnon-Rayleigh forbothland andseaclutter,butthespatialdistribution oflandclutterprovides interclutter visibility that permits thedetection oftargetsthatlieoutsidetheseparated clutterpatchesoflarge(J0.The non-Rayleigh pdf,however, limitstheutilityofthelog-FTC receiverandfrequency agilityin landclutter. 
 , 3EA CLUTTER IS A FUNCTION OF MANY PARAMETERS  SOME OF THEM SHOWING A COMPLICATED INTERDEPENDENCE  SO WE EMPHASIZE AGAIN THAT IT IS NOT AN EASY TASK TO ESTABLISH ITS DETAILED BEHAVIOR WITH A GREAT DEAL OF CONFIDENCE OR PRECISION &OR EXAMPLE  IN A PROPER SEA CLUTTER MEASUREMENT  THE POLARIZATION  RADAR FREQUENCY  GRAZING ANGLE  AND RESOLUTION CELL SIZE WILL HAVE BEEN SPECIFIED 4HEN THE WIND SPEED AND DIRECTION MUST BE MEASURED AT A REFERENCE ALTITUDE  AND IF THE RESULTS ARE TO BE COMPARED WITH THOSE OF OTHER EXPERIMENTERS  THE PROPER  DURATION AND  FETCH SHOULD BE AVAILABLE TO ENSURE  STANDARDIZATION TO EQUILIBRIUM SEA CONDITIONS 3INCE THESE MEASURED WINDS ARE RELATED TO THE WIND STRUCTURE AT THE SURFACE THROUGH THE ATMOSPHERIC BOUNDARY LAYER  THE SHAPE OF THIS LAYER MUST BE DETERMINED BY MEASURING THE AIR AND SEA TEMPERATURES 4O COM 
 EVER  PRESENTS THE RADAR SYSTEM DESIGNER WITH MANY MORE OPTIONS AND ALLOWS ARBI 
 • They must be compatible with the fact that the radar is operating in a “waveguide,”  namely the volume between the Earth’s surface and the ionosphere, with unique  possibilities for multiple propagation paths including round-the-world propagation,  significantly modifying the effective ambiguity function. • They must be able to achieve the desired measurement capability in the presence of  extremely strong ground clutter. • They must be designed so as to minimize distortion or corruption by the ionospheric  medium or, at least, enable such distortion to be estimated and mitigated by signal  processing after reception. 
 • The high-power solid-state transmitter that consists of many transistor modules distributed on the rows of a 3D radar (such as the AN/TPS-59), or employed at the elements of a phased array (as in PAVE PAWS), or configured as a transmitter for a conventional radar (as in the AN/SPS- 40 or the Canadian ATC radar known as RAMP). • The serial production of phased arrays for the Patriot, Aegis, PAVE PAWS, and Bl-B radar systems. • The interest in the radar cross section of targets brought about by the attempts to reduce the cross section of military vehicles; and advances in computer methods for predicting the cross section of complex targets. 
 IRE, vol. 37, pp. 340-355, April, 1949. 
 RADIUS   AE  AND THE ACTUAL 
 For most validation points, the difference between the two methods is less than 5 mm/yr. MaxD, MinD, MD, and RMS are 9.22, 0.03, 1.38, and 4.03 mm/year, respectively. The result of SBAS-InSAR coincides with that of leveling data, which indicates that SBAS-InSAR method is able to monitor land subsidence with acceptable precision. 
 A. Oliner  and G. H. 
 The surface wave can be avoided by spacing the elements more closely. Here, as in some other cases, it is seen that closely spaced ele- ments are beneficial for improving impedance matching for scanning arrays. Ob- viously, reducing the element spacing increases the number of elements and hence the cost without any increase in gain or reduction in beam width. 
 NATION OF ALTITUDE  RANGE TO THE TARGET  DENSITY OF TARGET THREATS  ANTENNA FOOTPRINT ON THE  %ARTHS SURFACE  RELATIVE TARGET AND CLUTTER DOPPLER  DWELL TIME AVAILABLE  PREDICTED TARGET STATISTICAL BEHAVIOR  TRANSMITTED FREQUENCY  AND DESIRED RESOLUTION   4HE MODE CATEGORY hAUTONOMOUS AND  CUED SEARCHv CONTAINS THE MODES MOST COM 
 Radar Conf., pp. 410-416, Washington, 1980. 27. 
 Any use is subject to the Terms of Use as given at the website. Sea Clutter.  SEA CLUTTER  15.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 FIGURE 15.11  Sea spikes at X band, 1.5° grazing angle, and various pulse widths: ( a) sea state 3 and  (b) sea state 1. Note equal amplitudes at the two polarizations and a 40 dB difference in clutter strength  between moderate and weak winds. 
 The radar's 12.5-ft by 16-ft planar array rotates at 5 r/min while phase-scanning a sin- gle pencil-type 1.45° azimuth by 1.9° elevation beam through 12 long-range search beam positions and 4 MTI beam positions in elevation. The instrumented cover- age of the radar is 250 nmi in range, 20° in elevation, 360 degrees0 in azimuth, and 120 kft in height. Target height is estimated by using sequential lobing between contiguous beams in elevation.29 A significant example of a long-range airborne 3D surveillance radar is the AWACS (Airborne Warning and Control System) AN/APY-1 S-band radar used on the E-3A aircraft. 
 H. Gent, The bootlace aerial, Royal Radar Estab. J . 
 HANDLING SYSTEM .   '2/5.$ %#(/  £È°Ó "ISTATIC -EASUREMENTS  -EASUREMENTS OF GROUND RETURN WHEN THE RECEIVER AND  TRANSMITTER ARE SEPARATED ARE COMPARATIVELY RARE 4HESE MEASUREMENTS ARE VERY DIFFICULT  TO MAKE FROM AIRCRAFT BECAUSE IT IS NECESSARY THAT BOTH TRANSMITTER AND RECEIVER ANTEN 
 WAVE DEVICE  HOWEVER  THE MAGNETIC FIELD DETERMINES THE FREQUENCY BUT THE FREQUENCY OF A CONVENTIONAL SLOW 
 Theechosignalistherefore independent ofrangeforaconstant­ altitude target. Inpractice, thepowerreceived fromanantenna withacosecant-squared pattern isnot trulyindependent ofrangebecauseofthesimplifying assumptions made.Thecrosssection (1 varieswiththeviewing aspect,theearthisnotflat,andtheradiation patternofanyreal antenna canbemadetoonlyapproxfmate thedesiredcosecant-squared pattern.Thegainofa typicalcosecant-squared antenna usedforground-based searchradarmightbeabout2dB lessthanifafanbeamweregenerated bythesameaperture. Themaximum gainofanantenna isrelatedtoitsphysical areaA(aperture) by G _41tAp -).2 wherep=antenna efficiency and),=wavelength ofradiated energy.Theantenna efficiency depends ontheaperture illumination andtheefficiency oftheantenna feed.Theproductofp.-l istheeffective aperture Ae.Atypicalreflector antenna withaparabolic shapewillproduce a beamwidth approximately equalto (2.50) whereIisthedimension oftheantenna intheplaneoftheangle0,and),andIaremeasured in thesameunits.Thevalueoftheconstant, inthiscasetakentobe65,depends uponthe distribution ofenergy(illumination) acrosstheaperture. 
 the maximum permissible diameter of the illuminated surface should be 3.56 ft. The  bearnwidtll required of the primary feed pattern is determined by the illuminated portion of  tlie aperture. Li used a square-aperture horn with diagonal polarization in order to obtain the  required primary beamwidth and low primary-pattern sidelobes (better than 25 dB). 
 and Y.L. Funding: This work was supported by the National Natural Science Foundation of China (No.61271297; No.61272281) and the Postdoctoral Science Foundation of China (No. 2017M610966). 
 As an example, the Analog Devices AD9858 Direct Digital Synthesizer47 uses a  10-bit DAC operating at up to a 1-GHz internal clock speed (DAC update rate). Digital Pulse Compression .48–50 Digital pulse compression techniques are  routinely used for matched filtering of radar waveforms. The matched filter may be  implemented by using a digital convolution for any waveform or else by use of stretch  processing for a linear-FM waveform. 
 S. Symons et al., “The constant efficiency amplifier—A progress report,” presented at NAB  Broadcast Engr. Conf. 
 The basic .concept of the linear frequency modulated (FM)  pulse--c6mpression radar was described by R. H. Dicke, in a patent filed in 1945.14 Figure  11.14, which is derived from Dicke's patent, shows the block diagram or such a radar. 
 Murray, J.P.: Electromagnetic Compatibility, chap. 29 of" Radar Handbook," McGraw-Hill Book  Company, New York, 1970.  51. 
 The application of digital technology to IQ  demodulation, which is just downconversion of an IF signal to a complex baseband,  has greatly improved the performance of coherent systems. Here, we explore two  forms of such digital downconversion, a general form that is structurally parallel to  traditional analog downconversion and a restricted form, direct digital downconver - sion, which is more economical when it is applicable. Analog Downconversion and Sampling. 
 SCANNING IN ELEVATION )T PROVIDES FULL PERFORMANCE OVER A NOMINAL n IN THE ELEVATION PLANE TO AN ALTITUDE OF   FEET AND UP TO  n  IN ELEVATION DURING 4"- TRACKING 4HE ANTENNAARRAY INCORPORATES MONOPULSE RADAR TECHNIQUES 4HESE TECHNIQUES ALLOW ACCURATE TARGET ANGULAR POSITION  USING THREE DATA CHANNELSSUM  DELTA AZIMUTH !:   AND DELTA ELEVATION %, WITHIN THE ARRAY AND THE DATA 
 CANCELER CONFIGURATION SHOWN IS SUCH THAT TWO OF THE ZEROS CAN BE MOVED AROUND THE UNIT CIRCLE IN THE  : PLANE -OVING THE ZEROS CAN PROVIDE A  OR  D" INCREASE IN THE -4)  IMPROVEMENT FACTOR FOR SPECIFIC CLUTTER SPECTRAL SPREADS  AS COMPARED WITH KEEPING ALL THREE ZEROS AT THE ORIGIN  .OTE THE WIDTH OF THE REJECTION NOTCHES FOR THE DIFFERENT BINOMIAL 
 430-435, March, 1959.  35. Gustafson, B. 
 angel echoes from. clear-air turbulence are not likely to bother most  radars.  Ocher angel echoes. 
 Ridenour, L. N.: "Radar System Engineering," MIT Radiation Laboratory Series, vol. I, chap. 
 Also, an actual N-bit ADC  never provides exactly 6N dB of SNR, due to ADC-induced errors. For example, a  typical 16-bit ADC generally provides about 14 bits or about 84 dB of SNR. Carrying  16 bits through the signal processing provides about 96 dB of dynamic range. 
  +A 
 10.11 Complementary-code aperiodic autocorrelation function. Implementation of Biphase-Coded Systems. Digital implementation is generally used to perform the pulse compression operation in biphase-coded systems. 
 First, high-angle cov- erage is limited by clutter from the stronger low-altitude section of the beam rather than from system noise. Second, ECM reduces both the maximum range . and the altitude coverage of the radar. 
 IRE  7'rnn~., vol. 11'-2, pp. 29-38, March, 1956. 
 10, pp. 204-221, 1953. 20. 
 E., J. D. Mallett, and I. 
 MoIs: A 250 kW Solid-State AN/SPS-40 Radar Transmit- ter, Microwave J., pp. 93-105, July 1983. 11. 
 COATED  METAL SHAPES v 0ROC )2%  VOL  PP n  *ULY   - ' !NDREASEN  h3CATTERING FROM BODIES OF REVOLUTION v  )%%% 4RANS  VOL !0 
 In contrast, the areas below Zhongxinhe Road in the image were mainly urban districts, where the silt content in the soil of the road foundation was lower, with mealy sand and silty clay as the dominant geotechnical content. Furthermore, compared to the upper stretch of the highway, the average thickness of the soft soil layer was only 3.57–7.62 m, with a lower water discharge ﬂow under the surface and an advanced drainage system in the urban areas. As a result, the settlement was much weaker. 
 )With the addition ofthis protective switch, the method ofFig. 17.13a issatis- factory. The addition makes it,however, nearly ascomplex asmore elegant methods ofregenerative tracking. 
 As discussed earlier, the null depths are essentially unaffected by  feedback. They are also essentially independent of the type of canceler employed,  whether single, dual, or triple, or of the number of hits per beamwidth. Figure 2.45  shows approximately what null depths can be expected versus the ratio of maximum  to minimum interpulse period. 
 The widely used source on noise is International Radio Consultative Commit- tee (CCIR) Report 322.36 This report is based upon measurements made at 16 lo- cations throughout the world. The measurement and data analysis was performed to exclude individual collection site local thunderstorm contributions. Spaulding and Washburn37 have added data from the U.S.S.R., and a revised CCIR report is available. 
 Dynamic Impedance. This indicates how rapidly the tube current changes for a given change in applied voltage (also see Table 4.2). The significance of this factor depends on the type of modulator used, or it may affect the HVPS capac- itor bank size required for a given permissible power droop during the pulse length (Sec. 
        
 354 INTRODUCTION TO RADAR SYSTEMS  the neck of the CRT to provide an axial magnetic field. Magnetic focus generally can provide  better resolution, but the spot tends to defocus at the edge of the tube.  The CRT display is by no means ideal. 
 For many MTI applications pulse-to-pulse or dwell-to-dwell staggering is pref - erable to scan-to-scan staggering.† For example, if a binomial-weighted three-pulse  canceler that has 36%-wide rejection notches is employed and if scan-to-scan pulse  staggering is used, 36% of the desired targets would be missing on each scan owing  to doppler consideration alone. This might be intolerable for some applications.  †  The choice between pulse-to-pulse staggering and dwell-to-dwell (MTD) operation is a system concept decision— both approaches have their advantages. 
 Compound Targets Extended through Space.—Targets such as rain, vegetation, 6’window,’” orthe surface ofthe sea are much more complicated than thetargets considered inthepreceding sections. Itis, however, easier topredict and verify certain features ofthe return from such targets because thecompound targets here considered arecomposed oflarge numbers ofindependent individual scatterers, and for that reason statistical considerations can beused intheir treatment. The aim ofthis statistical treatment istopredict the probability distribution ofthereturned power and ofthecorrelat ionofsuccessive measurements ofthereturn power. 
 The  individual unit cells of the coupled-cavity circuit resemble the ordinary klystron resonant  cavities. There is no direct coupling between the cavities of a klystron; but in the traveling­ wave tuhe, coupling is provided by a long slot in the wall of each cavity. The coupled-cavity  circuit is quite compatible with the use of lightweight PPM focusing, a desired feature in some  airborne applications. 
 Now letusconsider the fluctuations inthe case ofextended ground clutter. The echo from such clutter, aswehave already seen in Sec. 16.6, consists ofthevector sum ofthecon- tributions ofalarge number ofscattering ele- ments. 
 However,  due to the complex nature of the distortion mechanism in A/D converters, the amplitude  of IMD products is not easily characterized and predicted by the measurement of an  input intercept point. Input Noise Level and Dynamic Range.  Accurate setting of the A/D con - verter input noise level relative to the A/D converter noise is critical to achieving the  optimum trade-off between dynamic range and system noise floor. 
 COUNTERMEA 
 Formicrowave frequencies, therefore, onecanscarcely reduce storm echoes bymore than about 10db. Inthedetection ofships, whose velocities arecomparable with those of clouds, itmight bethought that theships would becanceled along with theclouds. This isnot sobecause ships, when within thehorizon, give much larger signals than clouds, and still show upstrongly after a10-db cancellation. 
 Such multiple-scale systems are described inChap. 6ofVol. 20oftheseries. 
 The setisshown inFig. 6.28. The two antenna reflectors are25by 10ft. 
 11.2 INFORMATION AVAILABLE FROM A RADAR  A radar obtains information about a target by comparing the received echo signal with the  transmitted signal. The availability of an echo signal indicates the presence of a reflecting  target; but knowing a target is present is of little use by itself. Something more must be known. 
 LINE PATHS TOWARD AN INTERCEPT POINT THE LOOK ANGLE OF THE RADAR  X  AND THE ASPECT ANGLE OF THE TARGET  X4 ARE  CONSTANT FOR A GIVEN SET OF RADAR AND TARGET SPEEDS  62 AND 64  RESPECTIVELY 4HE CENTER OF  THE DIAGRAM IS THE TARGET  AND THE ANGLE TO THE RADAR ON THE CI RCUMFERENCE IS THE ASPECT  ANGLE 4HE ASPECT ANGLE AND LOOK ANGLES SATISFY THE EQUATION  62 SINX    64 SINX4   &)'52%  5NFOLDED SPECTRUM WITH NO CLUTTER POSITIONING  . {°È  2!$!2 (!.$"//+  WHICH IS DEFINED AS A COLLISION COURSE 4HE TARGET ASPECT ANGLE IS ZERO FOR A HEAD 
 TRACKING SENSITIVITY VOLTS PER DEGREE OF ERROR  TO REMAIN CONSTANT  EVEN THOUGH THE TARGET ECHO SIGNAL MAY VARY OVER A LARGE DYNAMIC RANGE 4HI S IS ACCOMPLISHED BY  AUTOMATIC GAIN CONTROL !'#  TO KEEP THE SUM SIGNAL OUTPUT AND ANGLE 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.756x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 the resonant wave or Bragg frequency; therefore, the resonant wave responses peak  at ±1. The amplitude range for each plot is 60 dB. 
 Shrader: Interclutter Visibility in MTI Systems, IEEE EASCON '69  Cotrr.cntiorr Record. pp. 294-297, Oct. 
 BORNE EQUIPMENT OF THE AUTOMATIC IDENTIFICATION SYSTEM !)3  v )%#  
 Scott: The Parabolic Dome Antenna: A Large Aperture,  360 Degree, Rapid Scan Antenna, IRE WESCON Cotto. Record, vol. 2, pt. 
 With reflector antennas, it is not convenient to change  the antenna physical separation to compensate for changes in Oa or v. The pulse repetition  period TP might be varied to provide compensation, but this can introduce other complica­ tions into the radar design and the signal processing. With a phased array divided into two  overlapping subarrays, a constant pulse repetition frequency can be used and the horizontal  separation of the two overlapping subarrays can be controlled electronically to compensate for  platform motion. 
 T. F .. and F. 
 AND 
 TANEOUS TARGET $/! MEASUREMENTS FROM MULTIPLE RECEIVE SITES AT  KNOWN LOCATIONS  )T IS USED BY  30!352 AS A BRUTE 
 Derivation of wind speed from the corrected automat­ ic gain control (or from aD) is based on the work of  Brown et al. 3 and is implemented via a look-up table  having the relationship indicated in Fig. 9. 
 Pub. vol. 365, October 12–13, 1992, pp. 
 NOISE AMPLIFIER 4HE FIRST 42 MODULE WAS DEVELOPED BY 4EXAS )NSTRUMENTS IN THE MID 
 14.6 indicates the reduction instarting current effected bytheuse oftheauxiliary starting relay. 14.5. Voltage Regulators.—Since constant output voltage must be maintained despite changes inload, shaft speed, and d-cinput voltage, some form ofvoltage-regulating device isused with analternator. 
 For example, if the insertion and differential phase variations (which may occur from phase shifter to phase shifter) are known, they may be taken into account in the computations. Known temperature variations across the array that would induce phase errors may be compensated for. Finally, many feeds (e.g., optical and series feeds) do not provide equal phase excitation at the input to each phase shifter. 
 The balanced duplexer, Fig. 9.6, is based on the short-slot hybrid junction  which consists of two sections of waveguides joined along one of their narrow walls with a slot  cut in the common narrow wall to provide coupling between the two.38 The short-slot hybrid  Antenna  Receiver Figure 9.5 Principle of branch-type duplexer. /\nlenno  Transmitter  Antenna  Transmitter RECEIVERS, DISPLAYS, AND DUPLEXERS 361  Dummy load  Receiver  protector  ....... 
 II l\f icrowm•e J .. vol. 3, pp. 
 This may be proved by assuming that the sine in the denominator of Eq. (8.9) can be  replaced by its argument, so that the radiation pattern is of the form (sin2 u)/u2, where  11 = Nn(ri/A)(sin 0 - sin Oo) The (sin2 u)/u2 antenna pattern is reduced to half its maximum  value when rc = Lt_ 0.443~. Denote by O + the angle corresponding to the half-power point when  0 > (I,, and 0- , the arlgle corresponding to the half-power point when 0 < Oo; that is, 0. 
 Smith, “Statistical resolution limits and complexified Cramer-Rao bound,” IEEE Trans .,  vol. SP–53, no. 5, pp. 
 DUCE MORE TRACKING NOISE BUT  QUICKER RESPONSE TO MANEUVERS 4HE SE ERRORS ARE READILY  CALCULATED AS A FUNCTION OF @ AND A USING THE FORMULAS SHOWN IN 4ABLE  4O TUNE THE @ 
 VAL  WHICH IS TO BE USED  FOR THE REQUIRED hUNIFORMv AVERAGING /RIGINALLY  THIS AVERAG 
 SOLID-STATE TRANSMITTERS  11.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 The design challenge for high-power Si BJTs is to maintain a uniform high current  density over a large emitter area with a minimum temperature rise. High-frequency  devices require shallow, narrow, high-resistance base regions under the emitter  region, causing most of the current carried in the device to be crowded along the  periphery of the emitter. Thus, in order to maximize the current-handling capability of  the device and, hence, the power output capability of the device, the emitter periphery  is maximized. 
 Rogers, W. S. Hodgkiss, and L. 
 E. F. Knott, J. 
 TION IMPROVEMENT IN THE SILICON #-/3 INDUSTRY HAS RESULTED IN SUB 
 Trial Report No. 44/35, 13th August 1944 (TNA AIR 65/122) [15] Hendrie A 2010 The Cinderella Service, RAF Coastal Command 1939 —1945 (Barnsley: Pen and Sword Aviation) [16] Performance Stability of ASV Mark 6 Equipment on an Operational Squadron, TRE Report T.1894, July 1945 (TNA AVIA 26/896) [17] Sea Return Discriminator with A.S.V. Mks. 
 SPEED AIRBORNE APPLICATIONS  THERMAL  EROSION  AND OTHER AERODYNAMIC EFFECTS )N PRACTICE  THESE ENVIRONMENTAL FACTORS DETERMINE THE MECHANICAL  DESIGN OF THE RADOME   AND THE DESIRE FOR IDEAL 2& TRANSPARENCY MUST BE COMPROMISED BECAUSE MECHANICAL AND ELECTRICAL REQUIREMENTS ARE OFTEN IN CONFLICT 2ADOMES CAUSE FOUR MAJOR ELECTRICAL EFFECTS ON ANTENNA PERFORMANCE  "EAM DEFLEC 
 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17   blind folio 17 .38 ch17.indd   38 12/17/07   6:50:14 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 
 Mayer: Charge-coupled Devices and Radar Signal Processing. RCA Engr .. vol. 
 The modulator pulse indicates those cycles onwhich radar video istransmitted. Atrigger occurring only onthe beacon cycles can beformed byananticoincidence circuit operated bythese two pulses. The video switch separating the two types ofvideo iscontrolled bya flopover which isthrown tothe radar position whenever the modulator pulse occurs, and back tothe beacon position bythe next cosine pulse. 
 The operating life of a coaxial magnetron has been  said26 to be between 5,000 and 10,000 hours, which is a five- to twentyfold increase  compared to conventional high-power magnetrons. Limitations of Magnetrons.  When the magnetron was first introduced, it pro - vided a capability not available with the grid-controlled tubes used for early radars. 
 SIDELOBE LEVEL IS   -33, 
 The average effect on the improvement factor can be obtained by integrating this differential effect over the main beams: 2 fe° iG(e)i2c/ej — 60/scan = for single-delay cancellation (16.13a) f6° IG(0 + 7» - G(6)l2</0J -e0 y 6/-°e IG(0)|2</0 /scan = for double-delay cancellation fe° \G(Q + TJ)-2G(Q)+G(Q-TJ)\2dQ J-8° (16.13*) where B0 = null of main beam G(O) = two-way voltage pattern In order to treat scanning motion in the frequency domain, the apparent clut- ter velocity seen by the scanning antenna is examined to determine the doppler frequency. Each element of an array or incremental section of a continuous ap- erture can be considered as receiving a doppler-shifted signal due to the relative FIG. 16.14 Antenna scanning effects, (a) As seen by the antenna radiation pattern, due to the apparent change in azimuth of the scatterer, 62 - 9, = 6 Tp. 
 R. F. Harrington, Time Harmonic Electromagnetic Fields , New York: McGraw-Hill, pp. 
 ING BELOW   WHICH THEN BECOMES A CONVENIENT MEASURE OF THE WEDGE ANGLE IN WEDGE 
 4HIS CHAPTER ADDRESSES SURFACE 
 operating noise ternperat~tre.~~) If the receiver effective noise temperature is 'c, then  where F, is the system noise-figure including the effect of antenna temperature.  The enective noise temperature of a receiver consisting of a number of networks in  cascade is  where 7; and G, are the effective noise temperature and gain of the ith network.  The effective noise temperature and the noise figure both describe the same characteristic  of a network. 
 Charts  and their updates are loaded by CD-ROM or via a satellite communications link. On  some systems, the chart radar may have access to a server on the ship that centralizes  the distribution of such data to all equipment needing chart information. The user has the ability to choose the ENC vector layers shown on the display  of a chart radar. 
 ETERS ASSOCIATED WITH THE ALTIMETERS DESIGN ARE LISTED IN 4ABLE  4HE PULSE 
 226 THEEMPLOYMENT OFRADAR DATA [SEC. 75 EXAMPLES OFRADAR ORGANIZATIONS Inthe following sections are given very brief sketches ofafew radar organizations with which some experience hasbeen obtained. The systems described are, forthemost part, necessarily those setupinwar- time forthe purposes ofwar, and tothis extent donot represent useful models forpeacetime radar organizations. 
 10. V . A. 
  ,  ^2- ,4!",%  !REA AND $ETECTION 2ANGES FOR 'ENERAL /VALS OF #ASSINI #OURTESY 3CI4ECH  )NC .   ")34!4)# 2!$!2   ÓÎ° )F %Q  IS SATISFIED  EXTRAORDINARY MEASURES ARE USUALLY REQUIRED TO SUPPRESS THE  DIRECT PATH SIGNAL TO A LEVEL WHERE TARGETS CAN BE DETECTED  AS OUTLINED IN 3ECTION  ÓÎ°{Ê **  /" - /VALS OF #ASSINI CAN BE USED  TO DEFINE THREE OPERATING REGIONS FOR A BISTATIC RADAR   CO 
 Eachbeamcanbeconsidered a separate radar.Itis,however, costlyandcomplex. Thetransmitter radiates afanbeamfrom thesummation ofalloverlapping pencilbeamstogivethedesired elevation coverage. A separate receiver isprovided eachpencilbeamandsomemeansofinterpolation between the beamsisusedtorefinetheanglemeasurement. 
 This PPI rotates in synchronism with the radar an- tenna and executes itsrange sweep mthe proper time relation with theradar transmitter, butoperate? ataconstant intensity, receiving novideo signals. The cathode- ray tube used has ashort-persist- ence blue screen; the intensity is adjusted toamedium orlowlevel. Asthemoving spot oftheauxiliary PPI moves behind themap tobe reproduced, aphotocell placed twoPhotomultipl)er tube 7 ~Viewingaperture1 Transparency tobe reproduced FIG. 
 For example, suppose that the desired false-alarm time was 15 min and tht:  IF bandwidth was 1 MHz. This gives a false-alarm probability of 1.11 x 10-9. Figure 2. 
    PP n  -ARCH   0 3WERLING  h4HE @DOUBLE THRESHOLD METHOD OF DETECTION v 0ROJECT 2AND 2ES -EM 2- 
 Although the median detector is superior to tlie mean detector (conventional receiver). it  is inferior to both the nt-out-of-)] detector and the logarithmic receiver when clutter can he  described by the log-normal2' or the Weib~ll'~ models. The 111-out-of-tr detector, or binary  integrator, was originally employed in radar as an automatic integrator, hilt it has other  propertics of interest. 
 It is useful not just as a means for determining the  maximum distance from the radar to the target, but it can serve both as a tool for under-  standing radar operation and as a basis for radar design. In this section, the simple form of  the radar equation is derived.  If the power of the radar transmitter is denoted by P,, and if an isotropic antenna  is used (one which radiates uniformly in all directions), the power density (watts per unit area)  at a distance R from the radar is equal to the transmitter power divided by the surface area  4nR2 of an imaginary sphere of rapius R, or  pt Power density from isotropic antenna = - 4nR2  Radars employ directive antennas to channel, or direct, the radiated power Pt into some  particular direction. 
 Lee, C. Corson, and G. Mols, “A 250 kW solid-state AN/SPS-40 radar transmitter,”  Microwave J , vol. 
 16. F. V . 
 PRODUCT FROM A BEAMFORMING INTERFEROMETRIC ALTIMETER AND THEIR APPLICATION TO ELE 
   PP n  . 
 As shown earlier (Fig. 22.3), small deviations can cause a significant loss in antenna gain. Stable configurations are obtained by using low-coefficient-of- thermal-expansion (CTE) materials. 
 The bipolar video is converted to digital words in an analog-to-digital (AJD) converter. The AfD output is stored in a PRI memory and also subtracted from the memorized AID output from the previous transmitted pulse. FIG. 
 Res. , vol. 91, pp. 
 Both types of InSAR are discussed in Section 17.8. The former is discussed in  “Interferometric SAR for Moving Target Indication (MTI),” and the latter is discussed  in “Interferometric SAR for Target Height Measurement.” Inverse SAR.  Skolnik21 presents a discussion of Inverse SAR (ISAR). 
 MTI radars (Chaps. 15 and 16) with low pulse repetition frequencies (PRFs) and pulse doppler radars (Chap. 17) with high PRFs often use waveforms with multiple pulse repetition intervals in order to avoid range and/or doppler ambiguities. 
 57–60. ch12.indd   42 12/17/07   2:32:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 For a stripmap SAR, Eq. 17.22 then becomes  S c V δ ψcr≤( .) cos 4 7 (17.23) Range Migration.  As we have seen, a SAR may obtain range resolution of dr =  c/2B, where B = signal bandwidth, and obtain cross-range resolution through doppler  processing, with dcr = l/2∆q. 
 GROUND ECHO  16.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16  NP T x TR x dxe T= −   ∫2 02 1sf( ) (16.15) where Pe is the mean envelope power, T is the integration (averaging) time, and Rsf (t)  is the autocovariance function for the detected voltage. For many practical purposes,  if N is large, it may be approximated by  N ≈ BT (16.16) where B is the effective IF bandwidth. For the effect of short integration time, see  Ulaby et al.82 Fading samples can, of course, also be independent because motion of the vehicle  causes the beam to illuminate a different patch of ground. 
 Least squares on compressed sensing residuals (LS-CS-Residuals) can reconstruct the time sequences of sparse signals which change slowly with time. This is to replace CS on the observation by CS on the least squares (LS) residual computed using the prior estimate of the support. In this paper, we introduce LS-CS-Residual into WASAR imaging. 
 Since decoys can be made to closely resemble real targets, and  since a decoy might conceivably carry a bomb, one defensive strategy would be to destroy all  unfriendly targets, itlcluding known decoys.  Reducing the radar cross section of the target by proper shaping is another possible  passive countermeasure. A target with doubly curved surfaces (curvature in two dimensions)  will have small cross section. 
    
 CORRELATE IT WITH THE RETURNED ECHO  ALL IN REAL TIME 3INCE CROSS 
 4.10. Only in rare cases has it been possible to suppress these os- cillations completely. However, since this particular oscillation depends on elec- tron velocity, which in turn depends on beam voltage, the problem is avoided by the use of mod-anode or grid pulsing (described later in this section). 
 Ifthescanner and themodulator cannot besynchronized but thescanning isnevertheless reasonably uniform, theperiodic signal canbe. 692 [SEC. 175 1-b 1 1 I ~LKaltriggeroutputpuke -1 R,----} lL-u-Ll13E9 Tomixer~ F E ? k 0+inbiaslevel:~, 60CPS + ,,,, F III:::; I,:jtterin,, ,, \ pulseposition FIG. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.4  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 3D Volumetric Search.  Three-dimensional (3D) volumetric radar search is pos - sible with electronic scanning in both azimuth and elevation; important regions (e.g.,  the horizon) may be emphasized at will and searched more frequently. 
 TER  AND CHAFF  AND IN THE PRESENCE OF VARIOUS REFINED PROPAGATION MODELS IS WELL ESTAB 
 6.4 FEEDS Because most radar systems operate at microwave frequencies (L band and higher), feeds for reflector antennas are typically some form of flared waveguide horn. At lower frequencies (L band and lower) dipole feeds are sometimes used, particularly in the form of a linear array of dipoles to feed a parabolic-cylinder reflector. Other feed types used in some cases include waveguide slots, troughs, and open-ended waveguides, but the flared waveguide horns are most widely used. 
 SION REGION HAS TO BE  o  MS  THE CONSTRAINT FOR ALL DOPPLER FILTER DESIGNS NORMALIZED TO  THEIR PEAK IS AS SHOWN IN &IGURE  5SING A SIGNAL PROCESSING TOOLBOX DEVELOPED BY $R $AN 0 3CHOLNIK OF THE .AVAL  2ESEARCH ,ABORATORY  A DOPPLER FILTER BANK MEETING THE ABOVE CONSTRAINTS WAS DESIGNED 4HE FIRST FILTER  WHICH HAS ITS PEAK LOCATED AS CLOSE AS POSSIBLE TO THE LEFT EDGE OF THE CONSTRAINT BOX IS SHOWN IN &IGURE   WITH THE ABSCISSA NORMALIZED TO THE TOTAL AVAIL 
 If an off-axis feed is moved parallel to the focal axis, the region of minimum distortion moves laterally in the reflector. At the same time, if the reflector is a paraboloid of revolution, the focus in the orthogonal plane (usually the azimuth) is altered. For the reflector region directly in front of the displaced feed, it has been found that both planes are improved by moving progressively back from the focal plane. 
 29. pp. 623 639. 
 DRIVEN SEA SURFACE  AS A FUNCTION  OF WIND SPEED MODELED DATA  AND  THE WIND DIRECTION RELATIVE TO THE RADARS LOOK DIRECTION HORIZONTAL AXIS  3IMILAR FAMILIES OF CURVES CORRESPOND TO THE RADARS POLARIZATION USUALLY (( OR 66  AND ANGLE OF INCIDENCE #URVES SUCH AS THESE ARE DERIVED FROM A MODEL SUCH AS #-/$  SUBSEQUENTLY VERIFIED BY EXTENSIVE AIRBORNE MEASUREMENTS . 
 The amplitude of the pulse is taken  as the peak value. Dynamic-range considerations must take into account at least some  three orders of magnitude for range variation and three orders of magnitude for scan  pattern variations. In practice, 60 dB instantaneous dynamic range sounds like a mini - mum value; in many applications, it should be larger. 
 39. Kelleher, K. S., and H. 
 Ifthe modulation spectrum extends tomore than half the carrier frequency, spurious transients inthe carrier pass band may arise intwo ways. The modulation spectrum may have components that lieinthe carrier- channel pass band, ormodulation components may add tocarrier side- band components togive components lying within the carrier-channel pass band. Further, spurious components may arise from frequency modulation ofthe carrier oscillator bythe video signal. 
 96.Eastwood. L:..RadarOrnithology," Methuen &Co.,Ltd.•London. 1967. 
 Varela, A. A.: The Operator Factor Concept, Its History and Present Status, Symposium on Radar  Detection Theory, ONR Symposium Report ACR-10, Mar. l-2, 1956, DOC No. 
 The data were not  sufficient to avoid directional ambiguities, however. Nominal resolution was 50 km,  determined by the intersection of the antenna pattern and iso-doppler contours. The  radar operated at 14.6 GHz, radiating a peak power of 100 W at 17% duty factor from  a traveling wave tube amplifier (TWTA). 
 CONTROL RADARS  AND IN SOME MILITARY AIRBORNE RADARS 0HASED ARRAY TRACKER  !N ELECTRONICALLY SCANNED PHASED ARRAY CAN ALMOST  hCON 
 A. Watson and W. D. 
 D. E. Barrick and C. 
 (/2):/. 2!$!2   Óä°£ u %QUATORIAL PLASMA BUBBLES OFTEN APPEAR AFTER SUNSET AND CONVECT UPWARD THROUGH THE  & REGION WHERE THEY CONTRIBUTE TO STRONG DIFFUSE DOPPLER 
 where Go is the gain of the antenna in tile absence of errors, and 6 is the phase error, in radians,  calculated from the mean phase plane. This simple expression is valid for any aperture illumin-  ation and reflector deformation. provided that the latter is small compared to the wavelength. 
 CODED SIGNALS )N RECEPTION  THE JAMMER AND TARGET SIGNALS ARE CUT IN AMPLITUDE 4HE PRESERVATION OF THE TARGET SIGNAL PHASE CODING ALLOWS THE INTEGRATION OF TARGET ENERGY BY MEANS OF THE PULSE COMPRESSION FILTER MATCHED TO THE PHASE CODE 4HE $ICKE 
 That design may include materials with magnetic losses  as well as carbon particles responsible for electric losses. Therefore, the electric and  magnetic susceptances (relative permittivity and relative permeability) have imagi - nary components, resulting in an index of refraction with an imaginary component.  FIGURE 14.26  The Jaumann absorber is a cascaded collection of  thin resistive sheets stacked in front of a metal bulkhead, spaced l/4  apart, where K = spacer dielectric constant. 
 These latter two limitations are somewhat related by virtue of the physical construction of typical devices. Active transistor area on the surface of the chip is divided into cells, where the cell size is most often custom-designed for a particular application or range of appli- cations. Pulse width and duty cycle or, as a result, the peak and average dissipated power are the parameters that determine the cell size and arrangement of cells on a chip. 
 (AleerHOlll/hco/! andSmith.93)200 Weigh! 01Oird,q__--x \ \'\ x---x-- '\ I \'\'-I::;\ I 0", Oc . \ '-0,g;,\0/ ij,rr, , I _.:.._-------1->.. ..:-'------'----'-_-'I 500 1008x--- e 5V> V>eu (; u d?10. 
 60, pp. 743–744, June 1972.  6. 
 MANCE SEE &IGURE   LATER IN THE CHAPTER  FOR ALL ASPECT TARGET DETECTION    /FTEN  HIGH AND MEDIUM 02& WAVEFORMS ARE INTERLEAVED ON ALTERNATE SCANS SEE &IGURE   TO IMPROVE TOTAL PERFORMANCE    !FTER  YEARS OF SEARCHING FOR AN OPTIMUM SET  MOST  MODERN MEDIUM 02& MODES HAVE DEVOLVED TO A RANGE OF 02&S BETWEEN  AND  K(Z IN A DETECTION SET OF  FOR THE TIME ON TARGET  n 4HESE 02&S ARE CHOSEN TO MINIMIZE  RANGE AND VELOCITY BLIND ZONES WHILE SIMULTANEOUSLY ALLOWING UNAMBIGUOUS RESOLU 
 Starting from Equations (11.2)  and (11.5), the complex Radar cross- section σ can be defined with the transformation from  Equation (11.6).     € σξη=lim R→∞4πR2⋅ej2β(R−R0)⋅Eξr Eηi          2 =4πR02⋅EξS Eηi⋅ej2(ϕS−ϕi) ϕ      (11.7a)   (11.7b)   € R0   Range from the origin to the reference planes,   € ξ,η Orthogonal polarizations ( vertical or horizontal),   € ϕS   Phase of the ξ- components of the scattered field with R0,    € ϕi     Phase of the η- components of the incident field with R0.  The definition is so chosen that the absolute of σξη coincides with the known Radar cross - section σ from Equation (11.2). 
 29679, 1999. 124. Y. 
 27. Brigham, E. 0., and R. 
 L. Pugh, and LS. Reed: Control Loop Noise in Adaptive Array Antennas, IEEE Trans., vol. 
 A Sparsity-Driven Joint Image Registration and Change Detection Technique for SAR Imagery. In Proceedings of the 2010 IEEE International Conference on Acoustics, Speech and Signal Processing, Dallas, TX, USA, 14–19 March 2010; pp. 2798–2801. 
 TO 
 96 3.15 Structures ........ 99 3.16 Cities .......... 101 3.17 N’avigation ........ 
 The first large radomes (50-ft diameter or more) for ground-based radar antennas ap­ peared shortly after World War II. They were constructed of a strong, flexible rubberized  airtight material and were supported by air pressure from within.103 Since the material of  air-supported radomes can be relatively thin and uniform, they approximate the electrically  ideal thin shell which provides good electrical properties. Such radomes can operate with high  transmission efficiency at almost all radar frequencies. 
 J.: Mechanical Aspects of Ground-Based Radomes, Chap. 12 of" Mechanical Engincer-  ing in Radar and Communications," C. J. 
 W. D. White and A. 
 Model no. 4 not shown as it is a 3 gain model. ch07.indd   33 12/17/07   2:14:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 In search. the maximum rang2  of interest strongly affects the time resource. In tracking, the target range does not usually limit  the time resource since the range is known and the dwell interval can be adjusted accordingly. 
 # IN SOME PARTS OF THE WORLD  IN HIGH LEVELS OF WIND  VIBRATION   AND SHOCK AND ALSO IN HEAVY PRECIPITATION AND SALT WATER SPRAY %VEN WITHIN THE NOR 
 Typically the magnitude squared (represent - ing pixel energy) is displayed. As shown in Chapter 6 of Sullivan,1 a point target in the scene transforms to a two- dimensional point-spread function  (PSF) in the radar image, so-called because a point  target is displayed in the image as somewhat “spread out.” This PSF is characterized by  a mainlobe  and sidelobes  in both range and crossrange. Usually weighting  (also called  tapering  or apodization ) is applied in the processing, resulting in considerably lower side-   lobes, but at the expense of a somewhat broader mainlobe, a price that the user is typically  willing to pay. 
 April. 1969.  68 Srecial lsmc 011 Biological Effects of Microwaves, IEEE Trans., vol. 
 SYNTHETIC APERTURE RADAR  17 .356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17  8. R. O. 
 ASV Mk. VIA strobe unit and calibration control (A) used in the initial setting up of the bombsight [ 10]. Figure 4.23. 
 77 C7/1255-9, pp. 4-4A-4-40, Arlington, Va., 1977. 52. 
 VIDE I -..,.._  CO~f1AOL1 -.,.  APGj,  20 <m FT I  L~NO LI~ 'J' I  R{MOTING I OTHER RADAR TOPICS 537  Figure 14.9 diock diagram of the ASR-8 airport surveillance radar. APG is the azimuth puise generator  which provides antenna timing information, and CJ B is the cable junction box. 
 The difference frequency that results from mixing these two signals contains the same intelligence asdid the original r-f echoes, but itisatasufficiently low frequency (typically, 30Me/see) to beamplilied bymore orless conventional techniques intheintermediate- frequency amplifier shown. Output signals from the i-famplifier are demodulated byadetector, and theresulting unipolar signals arefurther amplified byavideo-frequency amplifier similar tothose familiar in television technique. The output signals ofthevideo amplifier arepassed totheindicator, which displays them, letussay fordefiniteness, inplan-position form. 
 123-129,  December, 1960. .: ..: .  7. 
 DETECTOR OUTPUTS GO TO ZERO  3OME OF THE TYPICAL  MONOPULSE FEEDS ARE DESCRIBED  TO SHOW THE BASIC RELATIONS AND  TRADEOFFS INVOLVED IN THE VARIOUS PERFORMANCE FACTORS AND HOW THE MORE IMPORTANT FACTORS CAN BE OPTIMIZED BY A FEED CONFIGURATION BUT AT THE PRICE OF LOWER PERFORMANCE IN OTHER AREAS  -ANY NEW TECHNIQUES HAVE BEEN ADDED SINCE THE ORIGINAL FOUR 
 For a further illustration that the ionosphere is stable during the measuring time, we also give the average TEC of ISR in different directions. The ISR data belonging to different beam directions were ﬁrst collected together, and a polynomial ﬁtting algorithm was adopted to form a smooth electron density proﬁle. Then average TEC of ISR was obtained by integrating the electron densities with respect to the altitude. 
 arid L. M. Spclncr: Polarization and Depression-Angle Dependence of Radar Terraill  Rcturn. 
 The MTD processor employs  several techniques for the increased detection of moving targets in clutter. Its implementation  is based on the application of digital technology. It utilizes a three-pulse canceler followed by  an 8-pulse FFT doppler filter-bank with weighting in the frequency domain to reduce the filter  sidelobes, alternate prrs to eliminate blind speeds, adaptive thresholds, and a clutter map that  is used in detecting crossing targets with zero radial velocity. 
 Speciﬁcally, Faraday rotation (FR) and TEC images were derived from PolSAR data, and ionospheric perturbations observed from variations of these images were veriﬁed using ground-based GPS receivers and network. Instead of analyzing relative variations in TEC images, we would like to quantitatively determine the precision of TEC retrieved from PolSAR, i.e., how precise the TEC could be when compared to that obtained from the powerful ISR. Furthermore, we would like to present a method for improving the topside electron density proﬁle of ionosonde using the precise TEC retrieved from PolSAR. 
 The radar community takes as its  job the successful application of radar in spite of what the EW community does; the  goal is pursued by means of ECCM techniques. The definitions of ESM, ECM, and  ECCM are listed below.8,11,12 † ESM is that division of EW involving actions taken to search for, intercept, locate,  record, and analyze radiated EM energy for the purpose of exploiting such radiations  in the support of military operations. Thus, ESM provides a source of EW information  required to conduct ECM, threat detection, warning, and avoidance. 
 SW.1618] THESUPERSONIC DELAY LINE 671 asthediameter ofthetube and directly asthesquare root offrequency. Anexperimental value is0.1db/in. at10Me/see with a~-in. 
 AVG ,OSS  HSD PL Y  C O S    4HIS AGREES WITH 3KOLNIK  %Q   AND #URLANDER ET AL  %Q  )T IS VERY USEFUL TO CONSIDER THE  NOISE 
 -Ê"Ê 
 TER FOR AIR SURVEILLANCE  THE INEXPENSIVE  COMMERCIAL BISTATIC RECEIVER HITCHHIKING  OFF WEATHER RADARS TO MEASURE FULL VECTOR WIND FIELDS   AND THE BISTATIC RADAR FOR  WEAPONS LOCATION &URTHERMORE  MAJOR PROGRESS HAS BEEN MADE IN DEVELOPING SIGNAL  AND DATA PROCESS 
 13, New York: McGraw-Hill Book Company, 1951.  2. R. 
 Target detec - tion requires detections in at least 3 of the 8 PRFs with all PRFs clear at maximum  range. The PRF selection criteria usually requires that the PRF set is 96% clear—in  other words, at least a specified number (typically 3) of PRFs must have an above  threshold return echo for the minimum specified target for the full specified range- doppler coverage. A typical processing block diagram is given in Figure 5.15. 
 HORN FEED IS SELECTED BECAUSE OF THE SIMPLICITY OF THE COMPARATOR THAT  REQUIRES ONLY TWO MAGIC OR HYBRID  4S FOR EACH POLARIZATION 4HE SUM AND DIFFER 
 +X D 0DX M 
 MINATION ON THE GROUND IS SHOWN INTERSECTED BY TWO ISODOPS LINES OF CONSTANT DOPPLER FREQUENCY   WITH THE WIDTH OF THE SPECTRUM BETWEEN THEM SHOWN O N THE DIAGRAM 4HE  DISTANCE BETWEEN THEM CAN BE SEEN TO BE AND  $ $RQ Q LQQ 
 TURES AND SURFACE ROUGHNESS ARE IMPORTANT FOR BOTH POLARIZATIONS #OHERENT PROCESSING TIME  4  &OR RANGES BEYOND THE SKIP DISTANCE  (& RADAR RETURNS  ALMOST INVARIABLY CONTAIN %ARTH BACKSCATTER AT THE SAME RANGES AS TARGETS $OPPLER  PROCESSING IS USED TO SEPARATE TARGETS FROM %ARTH BACKSCATTER HENCE  COHERENT SAM 
 ?'he coridit~on given by Eq. (14.10) is optimistic in that there are at least two factors which  result in the riglit -lii~ricI portioti being reduced. One sucli co~idition results froni tlie use of  acttral alltenria pattcrris ratlier tlia~i idealized patterns. 
 DIMENSIONAL ARRAYS  HORI 
 The beam may be scanned in space by  mechanical pointing of the antenna. Phased-array antennas have also been used for radar. In a  phased array, the beam is scanned by electronically varying the phase of the currents across  the aperture. 
 The Seasat satel - lite suffered a massive short circuit in its primary power system (in the solar panel  slip-ring assembly), which ended its mission in October 1978 after only three months  of operation. SIR SAR Series.  The Shuttle imaging radars, SIR-A (which flew on the first  Shuttle that carried a science payload), SIR-B, and SIR-C/X-SAR were essentially  technology (and science) demonstrations missions,2,9 each lasting about one week or  less. 
 36–46, and no. 10, pp. 31–36, 1972. 
 VI was also improved (see ﬁgure 7.3). Operating at 1000 ft, this would not have af fected performance at ranges greater than 1 nmi but it would have had an effect on the gain control required whenhoming in on a target at short range. The secondary lobe at a depression angle of 25°on the ASV Mk. 
 RMS  noiseSAMPLE   CLOCKERROR   VOLTAG E JITTERANALOG   SIGNA L ch25.indd   15 12/20/07   1:40:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 
 The output signal from thecrystal goes toone grid ofacoincidence tube, another grid ofwhich receives thesame sine wave used formodulat- ing the local-oscillator frequency. Only when thetwo coincide inphase = !&.will the coincidence tube conduct. ~ Asthefrequency ofthelocal oscilla- tordrifts across thecavity resonance curve, thecoincidence tube gives no output signal ontherising side ofthe1l\ /’ curve, and passes 1000-cycle pulses\1’ ‘Sk Derivative curve increasing inamplitude asthetopisFIG.12.13.—Beacon crystal current. 
 163. E. Brookner (ed.), Practical Phased Array Antenna Systems,  Norwich, MA: Artech   House, 1991. 
 Michaels: Radar Observations  of Insects in Free Fligl~t. Scirrtcc.. vol. 
 fro~n a turh~rlerlt ~tlcdii~ril is  wliere C:. thc structure constant, represents a measure of the intensity of tlie refractive-index  fluct\~ations, and A is the radar wavelength. At altitudes of several hundred meters. 
 The fence replaces the ground-reflected wave with a diffracted wave of  lesser importance. The diffraction fence also removes objectionable grot~rld clutter.  Tracking radars also are affected at low elevation angles by the ground-reflected wavc  The tracker might give an erroneous angle measurement just as in tlie case of the height finder,  or it might track the " image" in the ground instead of the trirc tar get. 
 MAGNETIC WAVE TO BE DESCRIBED IN TERMS OF LINEAR  ELLIPTICAL  AND CIRCULAR POLARIZATION LEFT 
 H.: Radar Astronomy. chap. 33 or .. 
 MM CLOUD RADAR MOUNTED ON A +ING  !IR AIRCRAFT )N THE MID 
 A human operator, however, cannot update target tracks at a  rate greater than about once per two seconds.69 Thus, a single operator cannot handle more  than about six target tracks when the radar has a twelve-second scan rate (5 rpm antenna  rotation rate). Furthermore an operator's effectiveness in detecting new targets decreases  rapidly after about a half hour of operation. The radar operator's trarfic handling limitation  and the effects of fatigue can be mitigated by automating the target detection and tracking  process with data processing called automatic detection and tracking (ADT). 
 The frequency range of propeller modulation  depends upon the shaft-rotation speed and the number of propeller blades. It is i~sually in the  vicinity of 50 to 60 Hz for World War I1 aircraft engines. This could be a potential soilrct: of  difficulty in a CW radar since it might mask the target's doppler signal or it might cailse an  erroneous measurement of doppler frequency. 
 SITE REGION WAS THE  -ULTISTATIC -EASUREMENT 3YSTEM --3   )T WAS INSTALLED AT THE 53 +WAJALEIN -ISSILE  2ANGE IN  AS AN ADJUNCT TO THE  42!$%8 , BAND MONOSTATIC RADAR  42!$%8  OPERATED IN ITS NORMAL MONOSTATIC MODE  ACQUIRING  TRACKING  AND ILLUMINATING BALLISTIC MISSILE REENTRY VEHICLES 26S  4WO UNMANNED  SLAVED RECEIVE STATIONS  LOCATED ABOUT  KM FROM  42!$%8  RECEIVED ECHOES BISTATICALLY SCATTERED OFF THE 26 AND RECORDED  BISTATIC RANGE  DOPPLER  AND SIGNATURE DATA FROM 26S 4HIS DATA WAS USED TO CALCULATE 26 POSITION AND DYNAMICS NEAR THE ATMOSPHERIC PIERCE POINT OR START OF RE 
 THE ECHO COMES HOME 57  operation and switches off the receiver, lest it be satur-  ated by the outgoing transmission. But, instantaneously,  the transmitter is then cut off, and for a comparatively  greater period of time the aerial is then connected to the  receiver, so that the returning echo may be picked up.  Then comes the next transmitted pulse, then a listening  period again, and so on, hundreds of times a second. 
 Rights & Permissions To obtain permission to re-use copyrighted material from Morgan & Claypool Publishers, please contact info@morganclaypool.com . ISBN 978-1-6432-7066-1 (ebook) ISBN 978-1-6432-7063-0 (print)ISBN 978-1-6432-7064-7 (mobi) DOI 10.1088/978-1-6432-7066-1 Version: 20180801 IOP Concise Physics ISSN 2053-2571 (online)ISSN 2054-7307 (print) A Morgan & Claypool publication as part of IOP Concise Physics Published by Morgan & Claypool Publishers, 1210 Fifth Avenue, Suite 250, San Rafael, CA, 94901, USA IOP Publishing, Temple Circus, Temple Way, Bristol BS1 6HG, UK. This work is dedicated to Liz.. 
  ALSO CARRIED RADAR ALTIMETERS 3ECTION   4HE %3! SERIES OF SATELLITES USE MIDDAY SUN 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 Meteors are usually classified as sporadic , occurring more or less randomly as the  Earth moves around the sun, and showers , such as the Leonids and the Eta Aquarids,  which occur on predictable dates where their orbits intersect the Earth’s orbit. 
 (Thi_s is not the same as the concept of" impedance match"  of circuit theory.) The ideal matcheo-ftlter·receiver cannot always be exactly realized in prac­ tice, but it is possible to approach it with practical receiver circuits. A matched filter for a radar  transmitting a rectangular .. shaped .pulse is usually characterized by a bandwidth B approxi­ mately the reciprocal of the pulse width 1, or Br ~ 1. 
  D" ,OW )3,2 IS  CLEARLY DESIRED -ULTIPLICATIVE .OISE 2ATIO -.2   4HERMAL NOISE GENERALLY INTERNAL WHEN THE  RADAR IS A 3!2  IS OFTEN REFERRED TO AS  ADDITIVE NOISE  SINCE IT ADDS TO THE SCENE INDE 
 LIMITED DETECTION  THE RADAR EQUATION TAKES THE FORM   3 .0' ' 4 & ,,.2TR P PS AVK  S P     WHERE   3.    OUTPUT SIGNAL 
 DCT is a classical autofocus method with good robustness and a small amount of computation. However, only the rotational motion is ignored, the DCT approach can provide the maximum likelihood estimation of the phase error. When one scatter or multiple scatters are located in a range bin, the motion compensation accuracy will decrease [ 18]. 
 SYNCHRONOUS SPACECRAFT   THAT HOST OPTICAL INSTRUMENTS SUCH AS *APANS !,/3  CHOOSE THE PHASE OF THE SUN ANGLE TO FAVOR ILLUMINATION OF THE SURFACE  WHICH USUALLY LEADS TO A MIDDAY ORBIT FROM WHICH MOST OF THE %ARTHS SURFACE IS VIEWED AT ABOUT THE SAME LOCAL TIME  NEAR MIDDAY 3UCH ORBITS IMPLY THAT THE SPACECRAFT MUST PASS THROUGH THE %ARTHS SHADOW ABOUT HALF THE TIME  WHICH HAS CONSEQUENCES ON THE DESIGN OF THE THERMAL AND POWER SUBSYSTEMS IN PARTICULAR )N CONTRAST  SPACECRAFT THAT CARRY ONLY RADARS  SUCH AS 2!$!23!4  TEND TOWARD FAVORABLE ILLUMINATION OF THE SPACECRAFT 4HE NATURAL RESULT IN THIS CASE IS THE SO 
   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°{x AN ADDITIONAL VARIABLE PHASE SHIFTER !  n BEAM SCANNED  n  FOR EXAMPLE  REQUIRES A  TIME DELAY OF  BITS  THE LARGEST BEING  WAVELENGTHS  AS WELL AS AN ADDITIONAL PHASE  SHIFTER 4HE TOLERANCES ARE TIGHT  AMOUNTING IN THIS CASE TO A FEW DEGREES OUT OF ABOUT   AND ARE DIFFICULT TO MEET 0ROBLEMS MAY BE DUE TO LEAKAGE PAST THE SWITCH  TO A DIFFERENCE IN INSERTION LOSS BETWEEN THE ALTERNATE PATHS  TO SMALL MISMATCHES AT THE VARIOUS JUNCTIONS  TO VARIATIONS IN TEMPERATURE  OR TO THE DISPERSIVE CHARACTERISTICS OF SOME OF THE COMPONENTS 0AINSTAKING DESIGN IS NECESSARY 4HE SWITCHES MAY BE DIODES OR CIRCULATORS ,EAKAGE PAST THE SWITCHES MAY BE REDUCED BY ADDING ANOTHER SWITCH IN SERIES IN EACH LINE 4HE DIFFERENCE IN INSERTION LOSS BETWEEN THE TWO PATHS MAY BE EQUALIZED BY PADDING THE SHORTER ARM 4HE VARIOUS PROBLEMS HAVE BEEN COMPREHEN 
 CIES  CONSISTS  OF  NINE  MEASUREMENT PROGRAMS  WHICH ARE SUMMARIZED IN 4ABLE  4HE MEASUREMENT ANGLES SHOWN IN 4ABLE  ARE DEFINED IN &IGURE   WHICH IS A CLUTTER 
 89-106, August, 1964.  41. Motkin, D. 
 E. Hiatt: Butler Network Extension to Any Number of Antenna Ports, IEEE  Trutis., vol. A P- 18, pp. 
 GATE TECHNIQUE SEE &IGURE   4HESE GATES ARE TIMED  SO THAT THE EARLY GATE OPENS AT THE BEGINNING OF THE MAIN RANGE GATE AND CLOSES AT THE CENTER OF THE MAIN GATE 4HE LATE GATE OPENS AT THE CENTER AND CLOSES AT THE END OF THE MAIN RANGE GATE 4HE EARLY AND LATE GATES EACH ALLOW THE TARGET VIDEO TO CHARGE CAPACITORS DURING THE TIME WHEN THE GATES ARE OPEN 4HE CAPACITORS ACT AS INTEGRATORS 4HE EARLY 
 The CFAR portion of the receiver is usually found just before the detection decision is made. It is required to maintain the false-alarm rate constant as the clutter and/or noise background varies. Its purpose is to prevent the automatic tracker from being overloaded with extraneous echoes. 
 S. Reed: Optimum Processing of Unequally Spaced Radar Pulse Trains for  Clutter Rejection. IEEE Tratts., vol. 
 The detections could be a friendly interferor, a jammer,  or an inadvertent interferor such as a faulty civilian communications transponder.99  This last example is the most common in the author’s experience. It is not uncommon  for a faulty transponder to appear as a million square meter tar get. Doppler Beam Sharpening (DBS).16,45,97 DBS is very similar to synthetic aper - ture radar (SAR) since both use the doppler spread across the antenna main beam to  create higher resolution in the cross beam direction.8,9,28,52 The principal difference is  the amount of angular coverage, beam scanning, resolution, data gathering time, and  accuracy of matched filtering in each range-doppler cell. 
 Thedifferent reflection coefficients withthetwopolarizations resultindifferent coverage patterns. Thenullsarenotasdeepwithverticalpolarization, norarethelobemaxima asgreat. Verticalpolarization mightbepreferred whencomplete verticalcoverage isrequired. 
 2557. July. 1969, Malvern, England. 
 An important feature, especially on ASV Mk. VI, was the introduction of the operator-selected sea discrimination circuit. As noted in [ 12] this was regarded as essential on ASV Mk. 
 Doppler centroid estimation is a central function implemented in all process - ing algorithms for SBR SAR data. Data Products.  The notional data product from a space-based SAR is imag - ery, usually visualized as a black-and-white mapping of the scene illuminated by  the radar. 
 SCANS RELATED TO THE SURVEY POSITION ON THE GROUND SURFACE 4HIS SEQUENCE CAN BE TERMED A " 
 POINTED BEAM 3TUDY OF THE RESULTS OBTAINED IN THIS TYPE OF ANALYSIS INDICATES THAT  IN REGIONS  WHERE THE SCATTERING COEFFICIENT DOES NOT CHANGE RAPIDLY WITH ANGLE  THE WIDEST POS 
 Grasso, G., and P. F. Guarguaglini: Clutter Residues of a Coherent MTl Radar Receiver. 
 However, thereduction of theorytopractice waspacedbytheavailability ofthenecessary signal-processing technology. Ittookalmosttwentyyearsforthefullcapabilities offeredbyMTIsignal-processing theoryto beconverted intopractical andeconomical radarequipment. Thechieffactorthatmadethis possible wastheintroduction ofreliable, small,andinexpensive digitalprocessing hardware. 
 ING RADAR v  )%%% 4RANS  -ICROWAVE 4HEORY AND 4ECHNIQUES   VOL -44 
 RANGE BALLISTIC MISSILES BY PROVIDING THE FIRING BATTERY WITH TARGET ACQUISI 
  MARKED A MAJOR MILESTONE  IN SPACE 
 V   AND &)'52%  )1 DEMODULATOR 
 Ragazzini: Optimum Filters for the Detection of Signals in Noise, Proc. IRE,  vol. 40, pp. 
 Thedomeneednotbea hemisphere butcanbeshapedtofavorparticular regionsofspace.Thedomecanconsistof dielectric-loaded circular waveguides inserted intoholesdrilledinthehemispherical shell.An experimental modelatCbandhadacombined mismatch andinsertion lossofabout0.8dB. Thedomemightalsobefabricated fromradome-like material usingahoneycomb skinwith lightweight printed-circuit phaseshiftsgluedtotheinnersurface. Inaconventional phasedarray,alinearphasegradient isappliedacrosstheaperture t,o steerthebeam.However. 
 Costantini, M.; Bai, J.; Malvarosa, F.; Minati, F.; Vecchioli, F.; Wang, R.L.; Hu, Q.; Xiao, J.H.; Li, J.P . Ground deformations and building stability monitoring by cosmo-skymed psp sar interferometry: Results and validation with ﬁeld measurements and surveys. In Proceedings of the 2016 IEEE International Geoscience and Remote Sensing Symposium, Beijing, China, 10–15 July 2016. 
 As the light from the spot is  not sufficient to illuminate the map itself subdued amber  lighting may be arranged through the glass walls of the  CRT, so that the map area is bathed in soft reddish  light, and the tracer-spot shines brightly in green if there  is an echo.  Reception along only one line would be of little use;  but if we arrange to swing our aerial slowly throughout  the entire 360 degrees, and move the trace clockwise  round the tube end in step with the aerial, then any  echo over the whole area will show up on the tube in  approximately its relative position with respect to the  centre, which, of course, is the position of the radar  station. As the aerial sweeps the circle the trace is  arranged to sweep the tube end in sympathy with it, and  thus the faint line of light of the trace represents the  aerial T and R beams. 
 PULSE BASIS GREATLY COMPLICATING BEAM STEERING CONTROL AND ABSOLUTE 42 CHANNEL PHASE DELAY !NOTHER CHALLENGE IS MINIMIZING POWER SUPPLY PHASE PULLING WHEN 02&S AND PULSEWIDTHS VARY OVER MORE THAN  RANGE -&!2 SYSTEMS NOT ONLY HAVE A WIDE VARIATION IN 02& AND PULSEWIDTH BUT ALSO USUALLY EXHIBIT LARGE INSTANT AND TOTAL BANDWIDTH #OUPLED WITH THE LARGE BANDWIDTH IS THE REQUIREMENT FOR LONG COHERENT INTEGRATION TIMES 4HIS REQUIREMENT NATURALLY LEADS TO EXTREME STABILITY MASTER OSCILLATORS AND ULTRA LOW 
 Its disadvantages are its relatively large  physical size when compared with other means for scanning and the large sidelobes obtained  in intermediate planes.  Organ-pipe scanner. Scanning tile beam in the parabolic torus is accomplished by moving a  single feed or by switching the transmitter between many fixed feeds. 
 The magnetron is still a valid candidate for small, non- doppler radars such as civil marine radars, although such radars also have been manu - factured with solid-state transmitters. It is not likely that magnetrons will be used in  high performance radars, especially those that require average powers more than one  or two kilowatts or where MTI improvement factors have to be greater than 30 to  40 dB. For example, during the procurement of the Nexrad doppler weather radar in  the mid-1980s, the magnetron was considered, but it could not meet the clutter can - cellation specifications, which is why Nexrad employs a klystron. 
 W., T. P. Cheatham, Jr., and J. 
 Considerable progress continues to be made in the development of tools for quanti - tative analysis60 of polarimetric SAR data. When in combination with interferometric  data,61 the field is known as PolInSAR, for which dedicated specialist meetings are  convened frequently. An important methodology is target decomposition,62 through  which specific backscatter classes (such as double-bounce, Bragg, or volume) of a  scene may be separated from other types, thence subjected to interferometric analysis. 
 PLICATED TARGETS MAY BE ESTIMATED BY REPRESENTING THE TARGET AS A COLLECTION OF FEATURES LIKE THOSE LISTED IN 4ABLE   CALCULATING THE INDIVIDUAL CONTRIBUTIONS AND THEN SUM 
  
 MODE      4WELVE 
   PP n    ! + &UNG  h! REVIEW OF VOLUME SCATTER THEORIES FOR MODELING APPLICATIONS v  2ADIO 3CI  VOL    PP n    9 3 +IM  h4HEORETICAL AND EXPERIMENTAL STUDY OF RADAR BACKSCATTER FROM SEA ICE v 0H$ DISSERTA 
 A. E. Acker, “Eliminating transmitted clutter in doppler radar systems,” Microwave Journal,   vol. 
    
 DUCED BY THESE JITTERS ARE UNCORRELATED  A REASONABLE APPROXIMATION  THE 2-3 SAMPLE 
 The radar antenna illuminates  the target with a microwave signal, which is then reflected and picked up by a receiving device. The  electrical signal picked up by the receiving antenna is called echo or return. The radar signal is  generated by a powerful transmitter and received by a highly sensitive receiver. 
 ***  Consisting of a push-pull, self excited oscillator, using a tuned cathode circuit.. 50AN/SPS-40 Surface Search  • UHF long range two-dimens ional surface search radar. 51AN/SPS-40 Surface Search  • UHF long range two-dimensional  surface search radar. 
 The wave reflected from the surface of the parabolic torus is not perfectly plane, but it can  be made to approach a plane wave by proper choice of the ratio of focal length! to the radius  of the torus R. The optimum ratio of fl R lies between 0.43 and 0.45. 39  Good radiation patterns are possible in the principal planes with sidelobes only slightly  worse than those of a conventional paraboloid. 
 Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 15.2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 grazing angle and the wind speed (or sea state), and generally to be greater for  vertical polarization and in upwind/downwind directions. (For other reviews of  sea clutter and its history, see Skolnik,2 Nathanson,3 and Long.4) Sea clutter is,  however, a complex phenomenon, presenting various faces depending on the way  the radar views the scene. 
 C. Jackson: Wide-angle Scanning Performance of Mirror Antennas, hlurcot~i  Rev., vol. 19, 3d qtr., pp. 
 An impor-  tant point is that the system is international and intro-  duces no language difficulty. Limitation of range is a  disadvantage, and the error at 300 miles is plus or minus  + per cent., and so the system cannot be used for blind  approach. The standard equipment weighs about  7a pounds, which is not considerable. 
 A phase predistortion technique  is described by Cook and Paolillo,3 which reduces the Fresnel amplitude ripple to  allow low time sidelobes to be achieved for LFM waveforms with relatively small  time-bandwidth products.  Radar equipment distortion sources also establish limitations on achievable time  sidelobe levels and are discussed by Klauder et al.1 and Cook and Bernfeld.2 The  method of paired-echo analysis is used to evaluate the effect of amplitude and phase  distortion on the time sidelobe levels. Frequency domain amplitude and phase dis - tortion is typically caused by filters and transmission line reflections. 
 34. Rihaczek, A. W.: Radar Waveform Selection-A Simplified Approach, IEEE Trans .• vol. 
 OUT SAMPLES GOING TO THE IMAGE SYNTHESIZER 4HE RANGE 
 J.: Optical Computing Techniques, IEEE Spectrum, vol. 1, pp. IOI 108, October, 1964. 
 The effect is small, however, at frequencies below X band. Water impinging on the  antenna feed can have serious effects. The wetting of surfaces through which signals are  transmitted should be avoided. 
 ES gives the sporadic-E distribution as M (median), L (lower), and U (upper) decile critical frequencies, in megahertz. This table shows the form of the stored data in the ionospheric model, and with it the various profiles can be generated. All these constants can be ad- justed to fit diagnostic observations. 
 The intersection of the bistatic plane and this ellipsoid  FIGURE 23.1  Bistatic radar north coordinate system for two dimensions,  establishing the bistatic plane. The bistatic triangle lies in the bistatic plane. ch23.indd   3 12/20/07   2:21:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Total spacecraft dry mass‡ is about 300 kg. TOPEX/Poseidon.  In the late 1980s, program planning for satellite radar altim - eter missions split into two themes, determined by the relative priority of their mea - surements. 
 These measurements were made in Georgia during the summer and fall months  and included deciduotis trees and pine trees. The grazing angles were from 2 to 25". The pulse  width was 100 ns and the antenna beamwidth was in the vicinity of one degree. 
 BEAM ANGLE ADDS TO PROCESSING DIFFICULTIES  VERY LIKELY REQUIRING 2ANGE 
 Thus, a larger aircraft with  slow yaw rates but greater wingspan generates a low-frequency noise spectrum simi - lar to that of a small aircraft with high yaw rates but smaller wingspan. However, the  larger aircraft typically has the broader noise spectrum because of the difference in  distribution of dominant reflectors. ch09.indd   27 12/15/07   6:07:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 H. Stiles, D. Brunfeldt, and E. 
 Reprinted in Barton, D. K.: "CW and Doppler Radars," vol. 7, Artech House, Norwood, Mass., 1978, sec. 
 POLARIZATION DESIGN PRACTICE IN A RADAR ANTENNA SYSTEM EXTENDS TO ANY AUXILIARY %##- ANTENNAS AS WELL )F THEIR CROSS 
 IRE , vol. 45, pp. 44–45, January 1957. 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing.  RADAR DIGITAL SIGNAL PROCESSING  25.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 FIGURE 25.40  CIC filter with decimation  after integratorNtR+ ++ − N = D/ RtFIGURE 25.39  Frequency response of third-order CIC decimation filter ( a) before decimation  and ( b) after decimation(a)−70−60−50−40−30−20−100 0 fs(in)/8 fs(in)/4 3fs(in)/8 fs(in)/2 −fs(in)/8 FREQUENCYGAIN (dB)BW (b)−70−60−50−40−30−20−100 0 fs(out)/4 fs(out)/2 −fs(out)/4 −fs(out)/2 FREQUENCYGAIN (dB)BW ch25.indd   31 12/20/07   1:40:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Skolnik (ed.).  McGraw-Hill Book Company, New York, 1970.  3. 
 ARRAY DEVICES v  0ROC )%%%  VOL    PP n  -AY    ' 7 *UDD  h4ECHNIQUE FOR REALIZING LOW TIME SIDELOBE LEVELS IN SMALL COMPRESSION RATIO CHIRP  WAVEFORMS v 0ROC )%%% 5LTRASONICS 3YMP    PP n   ! 0OHL  # 0OSCH  & 3EIFERT  AND , 2EINDL  h7IDEBAND COMPRESSIVE RECEIVER WITH 3!7 CONVOLVER v   )%%% 5LTRASONICS 3YMPOSIUM  PP n   8 3HOU  * 8U  ( 7ANG  AND 1 8U  h3!7 PULSE COMPRESSION SYSTEMS WITH LOWER SIDELOBES v   !SIA 0ACIFIC -ICROWAVE #ONFERENCE   PP n  4 -URAKAMI  h/PTIMUM WAVEFORM STUDY FOR COHERENT PULSE DOPPLER v  2#! &INAL 2EPT  PREPARED  FOR /FFICE OF .AVAL 2ESEARCH  #ONTRACT .ONR  X   !$  &EBRUARY     4 #OLLINS AND 0 !TKINS  h.ONLINEAR FREQUENCY MODULATION C HIRPS FOR ACTIVE SONAR v  )%% 0ROC 
 CLUTTER RATIO THAT PROVIDES STATED   PROBABILITY OF DETECTION FOR A GIVEN FALSE ALARM PROBABILITY IN AN AUTOMATIC DETECTION CIRCUIT  .OTE )N -4) SYSTEMS  IT IS THE RATIO AFTER CANCELLATION OR DOPPLER FILTERING 4HE CLUTTER VISIBILITY FACTOR IS THE RATIO BY WHICH THE TARGET SIGNAL MUST EXCEED THE  CLUTTER RESIDUE SO THAT TARGET DETECTION CAN OCCUR WITHOUT HAVING THE CLUTTER RESIDUE  RESULT IN FALSE 
 ANIC SURVEILLANCE VESSELS AND OIL PLATFORMS AS WELL AS SEA STATE   LAND 
 Also. IEEE Trans., vol. AES-14, pp. 
 02& RADAR  WHERE ALL 
 20–25. 10. D. 
 Thepresence -10 1 2 3 4 Angular frequency, W (al Cll '"co 5t10 ­ ~ " ~0.5­ "g0__~.1_~l_","-,-o<..-----'-_--'- ~0 liT (el ~~t.c:\. IL00 liT Frequency (d)Figure4.14(a)Three-pole Chebyshev low-pass filter characteristic with0.5dBrippleinthepassband; (b-d) delay-line filter';haracteristics derivedfrom(a).(After WhiteY). 114 INTRODUCTION TO RADAR SYSTEMS  i I Gut Delay T % c v  ' 0.61  Delay T ~Fl-e  / -  Figure 4.15 Form of the delay-line filter required to achieve the characteristic of Fig. 
 Imagine eachx todefineapointonastraight linecorresponding tothedistance fromafixedreference point. Thedistance ofxfromthereference pointmightrepresent thevalueofthenoisecurrentorthe noisevoltage. Dividethelineintosmallequalsegments oflength ~xandcountthenumberof timesthatxfallsineachinterval. 
  AND OTHER SPECIFICATIONS ON 2& SPEC 
 The V AD has been  implemented on the Nexrad as a standard product that can be used in precipitation and  ch19.indd   31 12/20/07   5:39:12 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 
 DETECTOR OUTPUT TO INDICATE TO THE SERVO WHICH DIRECTION TO DRIVE THE PEDESTAL )N A PULSED TRACKING RADAR  THE ANGLE 
 1963.  74. Quigley. 
 FREQUENCY SKY 
 A,, and R. G. Malech: Radiating Elements and Mutual Coupling, "Microwave Scar~rlir~g  Antennas, vol. 
 C. Hansen  (ed.), Academic Press, New York, 1964.  44. 
 Rosenberg: Very High Frequency  Radiowave Scattering by a Disturbed Sea Surace, /EE£ Trans., vol. AP-16, pp. 554· 568. 
 F. Winter. R. 
 Optionally, the negation of alternate samples at the output can now be relo - cated to the decimation’s output. Each delay that the negation crosses as it moves in  this transformation causes a net sign change in the signal, so each signal path between  the old location and the new that contains odd numbers of delays requires coefficient  negation to compensate. The result in the design of Figure 25.17 c is negation of alter - nate coefficients in the Q filter, as shown in Figure 25.17 c. 
 15–22, 1982.  6. M. 
 Range measurement with CW waveforms has been widely employed, as in aircraft radar altimeters and surveying instruments. Radial Velocity. From successive measurements of range the rate of change of range, or radial velocity, can be obtained. 
 The difference frequency resulting from the mixing  operation is twice the doppler frequency. A stable transmitter frequency is not needed in this  system as it is in the coherent system. Coherence is obtained on a relative basis in the process  of comparing the signals received from the forward and backward direction. 
 For this processing with a CIT of 12.8 s, the doppler filter bandwidth is a nominal 0.08 Hz, and at least 256 doppler filters should be used. The distance between the minimum noise points and the maxi- mum clutter points is of the order of 100 dB, which indicates the dynamic range requirement if small targets are to be seen. For digital processing, an analog-to- digital (A/D) converter of at least 16-bit accuracy is in order. 
 (23.43) is nonuniversal. Despite this fact, Battan10 lists four expressions as being "fairly typical" for the following four types of rain: Stratiform rain53 Z = 200 R16 (23.45) Orographic rain54 Z = 31 R111 (23.46) Thunderstorm rain55 Z = 486 R137 (23.47) Snow56 Z = 2000 R2 (23.48) Stratiform refers to widespread, relatively uniform rain. Orographic rain is pre- cipitation that is induced or influenced by hills or mountains. 
 Thecellscandriftwiththewindandalignthemselves in..streets." Muchoftheknowledge ofthebehavior ofconvective cellshasbeenobtained fromradar measurements.70.IO~ lOA I\natmospheric layerisastratum withinwhichthemeanverticalgradient and/orthe variance ofrdractive indexarcmuchgreaterthanelsewhere. Layersmaybefromafewmeters tomorethanahundred metersinverticalthickness andmightextendinthehorizontal from aboutonekilometer toseveraltensofkilometers. Layershavebeenobserved fromaltitudes of about0.3tomorethan22km.withthegreatest numberappearing inthevicinityof1to 2km.I07.I09 Atypicallayerassociated withasubsidence inversion mightexhibitadecrease of about20Nunitsinathickness of30to50milo[whereN=(11-1)106,n=refractive index]. 
 ANNUAL CHANGES ARE THE OBJECTIVE 4HE #RYO3AT ALTIMETER  IS THE FIRST SPACE 
 Although Marconi predicted and successfully demonstrated radio communication be-  tween continents, he was apparently not successful in gaining support for some of his other  ideas involving very short waves. One was the radar detection mentioned above; the other was  the suggestion that very short waves are capable of propagation well beyond the optical line of  sight-a phenometlon now know11 as tropospheric scatter. He also suggested that radio waves  be used for the transfer of power from one point to the other without the use of wire or other  trat~smissiot~ lit~cs. 
 p. 86, 1958.  63. 
 ORDER TERMS OF THE EXPANSION BECOME PROGRESSIVELY MORE  DIFFICULT TO OBTAIN 4HE 2#3 PATTERN OF A 2AYLEIGH SCATTERER IS VERY BROAD  ESPECIALLY IF THE OBJECT HAS SIMILAR TRANSVERSE AND LONGITUDINAL DIMENSIONS 4HE MAGNITUDE OF THE ECHO IS PROPORTIONAL TO THE SQUARE OF THE VOLUME OF THE OBJECT AND VARIES AS THE FOURTH &)'52%    !ZIMUTH 
 plate volt- age,kv 3.5 5.0 15.0 20.0 15.0 30.0 37.5 30.0 IPulse Emis- cur- sion, rent, amp/ amp watt, 5 0.5 8 0.57 15 0.27 15 0.27 6 0.05 15 0.11 15 0.10 60 0.08cutoff plate griddrop,vOlt-Voltsage* –70 –100 –500 –500 –900 –1000 –500 –1200400 600 1500 1500 2000 1500 2000 15009,creen volt- age 800 Soo 1200 1200 2000‘ositive grid drive, volts 150 150 200 200 200 1500 1500 1500 *0,2-ma cutoff. Agood output pulse tube must possess asharp grid cutoff. For efficient operation, theplate current must beonemilliampere orlesswhen thegrid isbiased tosome reasonable value. 
 12, pp. 238–244, 1955. 43. 
 Note:  In MTI systems, it is the ratio after cancellation or doppler filtering. The clutter visibility factor is the ratio by which the target signal must exceed the  clutter residue so that target detection can occur without having the clutter residue  result in false-target detections. The system must provide a threshold that the targets  will cross and the clutter residue will not cross. 
 From these performance curves, one sees that the  small signal gains are nearly identical in the 12–13 dB range, as are the large signal  efficiencies, but the power output capability of the GaN HEMT is 8 dB greater than  for the GaAs PHEMT of the same size. 11.4 DESIGNING FOR THE SOLID-STATE   BOTTLE TRANSMITTER Radar transmitter design invariably requires significant radiated power from the  antenna in order to project to the minimum range requirement while maintaining some  minimum signal-to-noise ratio on receive. The impact of the requirement for high radi - ated power is fundamental to the design of solid-state transmitters—high power must  be achieved by combining the outputs of lower-power amplifiers in order to develop  the required radiated levels. 
 2AO BOUND ! DISADVANTAGE OF THIS DETECTOR IS THAT IT IS SUSCEPTIBLE TO  INTERFERENCE THAT IS  ONE LARGE SAMPLE FROM INTERFERENCE CAN CAUSE A DETECTION 4HIS PROBLEM CAN BE MINIMIZED BY USING SOFT LIMITING 4HE DETECTION PERFORMANCE DISCUSSED PREVIOUSLY IS BASED ON THE ASSUMPTION THAT THE  TARGET IS CENTERED IN THE MOVING WINDOW )N THE REAL SITUATION  THE RADAR SCANS OVER THE TARGET  AND DECISIONS THAT ARE HIGHLY CORRELATED ARE MADE AT EVERY PULSE (ANSEN  ANA 
 308–341,  March 1991. ch11.indd   35 12/17/07   2:25:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 To validate the InSAR results, we also employ 56 leveling benchmarks where two readings of elevation were recorded in September 2016 and March 2017, respectively. T able 1. Parameters of Radarsat-2 WUF SLC images. 
 AP-9, pp. 470-483, Sept., 1961.  73. 
 BASE JUNCTION CAPACITY CHARGING TIME  THE BASE TRANSIT TIME  THE COLLECTOR DEPLETION 
 S. B. Colegrove, A. 
 Abel, J. E., S. F. 
 Substituting A4 = 2n into Eq. (3.17) gives the maximum unambiguous  range as 112. At radar frequencies this unambiguous tange is much too small to be of practical  interest. 
 It operates with an anode voltage of 5.8 kV and an anode current of 5.0 amps.  Typically, its pulse width might be 1.0 µs with a duty cycle of 0.001. The manufac - turer claims an expected typical life of over 10,000 hours and guarantees a minimum  life of 3,000 hours. 
   4S    S FOR TARGETS WITH ESTIMATED SPEED BETWEEN  AND  MS 
 STATE TRANSMITTER WAS PUT INTO PRODUC 
  
 12.10, a gradient dnldh = - 1.57 x m-'  will make tile effective earth's radius infiriite which allows initially horizontal rays to follow the  curvati~re of the eartl~. IJnder sucli conditions, the radar range is significantly increased and  detectiori beyond tlie radar horizon can result.  l'lie abnormal propagation of electromagnetic waves is called superreji-action, trapping,  dtrctirrq, or c~r~ott~rrlolts l~roptrgotio~l. 
 Radar System Engineering  Chapter 12 – Selected Radar Applications  138     -0,4-0,200,20,40,60,811,21,41,6 -15 -10 -5 0 5 10 15Beam 1 Beam 2 Sum beam   Figure 13.4  Transmitting monopulse directivity characteristic in the ψ−plane (equivalent  θ−plane).     When receiving the reflected signals will be received over both gates.  The hybrids each form  sums and differences ( Σ−Δ), as shown in Figure 13.5 and 13.6. 
 Figure 6.35 shows theantenna installation. The equipment operated at12cm, and had a12-in. dish giving a beamwidth ofabout 25°. 
 When the radar must detect a small target located on the surface of the sea or land, the interfering unwanted clutter echoes can severely limit the detectability of the target. When clutter power dominates receiver noise power, the range equation simply reduces to an expression for the signal- to-clutter ratio. This ratio is equal to the ratio of the target cross section to the clutter cross section. 
 SECTION OF THE SEA SURFACE  2ADAR MODULATION TRANSFER FUNCTION v  * 'EOPHYS  2ES  VOL   NO #      % & +NOTT  * & 3HAEFFER  AND - 4 4ULEY   2ADAR #ROSS 3ECTION   ND %D  "OSTON !RTECH  (OUSE    - 3 ,ONGUET 
 Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  134     [11] Kowatsch, M., and Stocker, H.R., "Effect of Fresnel Ripples on Side lobe  Suppression in Low Time -Bandwidth Product Linear FM Pulse Compression", IEE  Proceedings , vol.129, Pt. F, No.1, pp.41- 44, February 1982. Radar System Engineering  Chapter 12 – Selected Radar Applications  135     13 Selected Radar Applications   13.1 Tracking Radar   The exact position of the target is required for a few applications of Radar technology. 
 Triangular arrangement ofelements. I52.154Iftheelements ofaplanararrayarearranged ina patternofequilateral triangles ratherthansquares, asavingscanbehadinthetotalnumberof elements needed. Thisassumes thatthenumber ofelements inanarrayisdetermined bythe requirement thatnospurious beams(grating lobes)appearintheradiation pattern. 
 12ichriian. P. M.. 
 #OLE EQUATIONS WITH DIF 
 FIGURE   8. 8 Surface-wave delay line ch08.indd   11 12/20/07   12:49:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 One feature not found in other radar receivers is a means of extracting the  conical-scan modulation, or error signal. This is accomplished after the second detector it1 the  video portion of the receiver. The error signal is compared with the elevation and azimuth  reference signals in the angle-error detectors, which are phase-sensitive detect0rs.j ' A pl~ase-  sensitive detector is a nonlinear device in which the input signal (in this case the angle-error  signal) is mixed with the reference signal. 
 Thefamiliarexpression forthermalnoisepoweratmicrowave frequencies (No=kT,wherek=Boltzmann's constant andT=absolute temperature) doesnotapplywhenkT~hIItisthecoarseness ofthelaser signalitself.duetoitsquantized nature,thatultimately setsthelimittosensitivity asgivenby Fq.(14.3R).BysetlingkJ:. =Ill:an"equivalent noisetemperature" canbeobtained foralaser recciver. AttheCO2laserwavelength of10.611m,I;.=1360Kandat1.011mwavelength 7;.=14.400K.whichindicates thatlaserradarreceivers aregenerally ofgreatereffective temperature (ornoisefigure)thanlow-noise microwave receivers. 
 3CALING  !LGORITHM #3!  SEE #HAPTER  OF #ARRARA ET AL   3QUINTED 3TRIPMAP 3!2  )N THIS CASE  THE ANTENNA BORESIGHT IS NOT NORMAL TO  THE FLIGHT PATH !S SEEN FROM A TOP VIEW  THE  SQUINT ANGLE  PSQ IS THE ANGLE BETWEEN  THE ANTENNA BORESIGHT AND THE NORMAL TO THE FLIGHT PATH THUS  FOR A BROADSIDE BEAM   P SQ    AND CCR   $ -ORE GENERALLY    $PPP!  L $COSSQ      DL CRSQ   $PP$COS  )T  IS ASSUMED HERE THAT THE SYNTHETIC APERTURE LENGTH  ,3!  2 AND PSQ IS ESSENTIALLY  CONSTANT DURING A DATA COLLECTION $EPENDING ON DETAILS  THIS CONDITION IS VALID ONLY FOR P SQ LESS THAN ABOUT   SINCE  FOR A GIVEN CROSSRANGE RESOLUTION  AS  PSQ INCREASES   ,3!  INCREASES  AND THE CONDITION BECOMES NO LONGER VALID 3POTLIGHT 3!2  3POTLIGHT 3!2 SOMETIMES CALLED hSPOT 3!2v  IS USED TO OBTAIN  A RELATIVELY FINE 
 121. I. J. 
 Both have since found wide new appli-  cations, the German fighting forces using frequency  modulation considerably, and more recent non-radar  navigational systems have used continuous-wave trans-  missions for range-finding.  A. F. 
 The output of a matched-filter receiver is . ;, Q)  O'  0 -0 > THE RADAR EQUATION 17  T i m e ------*  Fi~un· 2.1 Typical envelope of the radar receiver output as a function of time, A, and B, and C represent  signal plus noise, A and B would be valid detections, but C is a missed detection,  the cross correlation between the received waveform and a replica of the transmitted  wavcf orm. Hence it does not preserve the shape of the input waveform. 
 Ihrst inimportance, ofcourse, aretheecho signals, which may contain asmany asseveral million separate pieces ofinforma- tion each second. The exact instant atwhich the radar pulse istrans- mitted isknown byvirtue ofapulse toorfrom the modulator. The geometrical coordinate ofrange isproportional tothereturn time ofthe echo pulses with respect tothis pulse. 
 For a circular aperture with uniform distribution, the  field intensity is proportional to  tn .ro  E(4) = / d0 1 exp r dr = nrg2~1(t)/S  ' 0 0  where < = 2k(ro /A) sin 4 and J ,(t) = first-order Bessel function. A plot of the normalized  radiation pattern is shown in Fig. 7.4. 
 The total map dynamic range can  easily be greater than 60 dB. The typical cockpit display is limited to 15–25 dB and  dynamic-range compression, such as converting map amplitudes into their logarithms,  is often performed. DBS or SAR PRF, Pulse Length and Compression Selection. 
 It is clear that the bottomside proﬁle of ionosonde matches well with that of ISR, while the two topside parts are divergent. The reason for this was discussed previously, i.e., that no topside information is considered in the original method. After modifying the topside proﬁle with the known TEC, we can easily see that the new topside proﬁle is more consistent with that of ISR. 
 It is applicable to forward-wave CFAs, but  it is llot usually used wit11 backward-wave CFAs since the variation of output power wit11  frcqi~cncy at a constant d-c voltage that is characteristic of backward-wave tubes would limit  tljc harldwidtl~ to but a few percent.  It is also possible to turn ttie CFA on and off with the RF drive-pulse, without the need for  a positive pulse applied to the cutoff electrode at the end of the drive pulse. The cutoff  clcctrodc call be designed to operate with an appropriate constant positive-bias that allows  stlfficietit reentrance of the electrons when the RF drive is on but be unable to maintain the  electron stream with ttie RF drive off.I7 This is called RF keyirtg, or self-keying. 
 However, when distracted, tired, overloaded, or not properly trained,  operator performance will decrease. There is little guidance available on how to account for  the performance of an operator.  Based an both empirical and experimental results, one study6' gives the operator-  efficiency factor as  PO = 0.7(Pd)2 (2.53)  60INTRODUCTION TORADAR SYSTEMS 18 16 14- ~12 ::;10o g'8 iiic-o6-- (5u4-- 2n=1 n=8 Linear detector ~~~~4}----_n=8 Square-low __----~~- detector ,........".....-'- n=l- ~~ Figure2.29Collapsing lossversuscollapsing ratio(m+11)/11,forafalsealarmprohahilily ofJO-banda detection probability of0.5.(FromTnl/lk,ss courtesy Proc.1EEE.) Nonideal equipment. 
 Radar antennas can be classified into two broad categories, optical antennas and array antennas. The optical category, as the name implies, comprises antennas based on optical principles and includes two subgroups, namely, reflector antennas and lens antennas. Reflector antennas are still widely used for radar, whereas lens antennas, although still used in some communication and electronic warfare (EW) applications, are no longer used in modern radar systems. 
 The panels should be non-erosive,  water repellent, and designed to reject much of the incident solar radiation. In somc radomes,  the exterior surface is coated with a white radar-transparent paint, such as Hypalon, to reduce  the interior temperature rise caused by solar radiation.  A rnctal space-frame radsme might consist OF individual triangular panels ~nacic tap of a  frame of aluminum extrusions encapsulating a low-loss dielectric reinforced plastics laminate  membrane. 
 The cathode-ray tube (CRT) has been almost universally used as the radar display. There  are two basic cathode-ray tube displays. One is the dejection-modulated CRT, such as the  A-scope, in which a target is indicated by the deflection of the electron beam. 
 END SACRIFICE THE HIGH AGILITY THAT IS NEEDED WHEN THE RADAR IS CHANGING FREQUENCY  TYPICALLY BY SEVERAL -(Z  SECOND BY SECOND  AS IT JUMPS BETWEEN TASKS 4HERE ARE ALSO PENALTIES FROM I  FILTER SWITCHING TIME  II  SET 
 13.52.—Range-height indicator for rapid-scan ayatem.. SEL!. 13.19] THE RANGE-HEIGHT INDICATOR 547 C03 e=1aresufficiently good approximations. 
 QUENCY WINDOW FOR SATISFACTORY PROPAGATION %VEN OUT 
 1, Johns Hopkins University, Appl. Phys. Lab. 
 TATIONAL CAPACITY OF MODERN RADAR SYSTEMS  HOWEVER  CAN MAKE THIS MORE ATTRACTIVE  "ARKER #ODES ! SPECIAL CLASS OF BINARY CODES IS THE "ARKER  CODES "ARKER CODES  ARE BINARY CODES WITH PEAK TIME SIDELOBE LEVELS EQUAL TO nLOG .   WHERE  . IS THE  LENGTH OF THE CODE 4HE ENERGY IN THE SIDELOBE REGION IS MINIMU M AND UNIFORMLY DIS 
 RECEIVER ONLY #/32/  SYSTEM  WHERE THE TRACKING RADAR RADIATES A NONSCANNING TRANSMITTING BEAM BUT RECEIVES WITH A CONICAL 
 VATIONS 5(& WIND PROFILERS OPERATING AT  -(Z IN THE 53 AND n -(Z  . £°{ä  2!$!2 (!.$"//+  IN %UROPE COVER THE LOWER ATMOSPHERIC WINDS UP TO n KM OR A FEW KM HIGHER WITH  LARGER ANTENNAS  WHERE THE STRONG MOISTURE FLUCTUATIONS PRESENT IN THE ATMOSPHERIC BOUNDARY LAYER PROVIDE STRONG SCATTERING SIGNATURES AT THESE SHORTER WAVELENGTHS 4HESE 5(& BOUNDARY 
 Staprans, A.: Linear Beam Tubes, chap. 22 of" Radar Technology," E. Brookner (ed.), ~rtech House,  Inc., Dedham, Mass., 1977. 
 August. 1958.  24 Crane. 
   SIMULTANEOUSLY DETECTED TARGETS CAN BE RESOLVED GHOST 
   &IGURE B  IS AN EXAMPLE OF AN OPTICALLY  FED ARRAY LENS WITH THE ANTENNA MOUNTED ON A TWO 
 75 Cl10 938-1 AES.  80. Meyer. 
     $ 
 G .. R. Eames. 
  
 The gamma  drop-size distribution24 is given as  N(D) = N0 Dm e –ΛD (19.49) with m > –1 and ΛD0 = 3.67 + m. The m parameter controls the shape of the distribution  and when m = 0, the distribution is exponential. Clearly, a single-wavelength, single-polarization radar can measure only a single  parameter Z and must assume Rayleigh scattering. 
 Tlie  frequency dependence indicated by the data of Ref. 37 is independent of the polarization and  of the angle of incidence (at least over the range from 8 to 30").  Measurements of crops4' and dry trees4' indicate that above .Y band, rrO varies approxi-  itlately linear with frequency, even up to 3.2-mm wavelength. 
 TO 
 The basic pulse triggers adelay circuit which iscontrolled bythe final output voltage insuch away that, assuming this voltage isright, the delay circuit produces apulse shortly before thearrival ofthesine pulse. The delay-circuit pulse triggers aflopover (Sec. 13.7) which inturn sends apulse down animproperly terminated delay line. 
 £Ó°ÓÓ  2!$!2 (!.$"//+  WHERE THE ECCENTRICITY E OF THE HYPERBOLOID IS GIVEN BY   E   SIN;XV   XR   =  SIN;XV  
 (6) For each interferogram, t1and t2represent the acquisition date of master and slave images, respectively. Equation (6) is introduced into the original time-series deformation model, and the low-pass deformation component of the model can be rewritten as a combination of linear and rheological components: SLOS=v(t2−t1)+SLOS _rhe (7) After substituting Equation (7) into Equation (1), the phase in Equation (1) can be expressed as Δϕp i=4πcosθ λ⎭bracketleftBigg Hσc E(t2−t1)−ηHσc E2⎭parenleftbigg e−E ηt1−e−E ηt2⎭parenrightbigg⎭bracketrightBigg +v(t2−t1)]+4πBi λRpsinθΔZp+Δϕres,p i. (8) Suppose there are Ninterferometric pairs generated, and that the unknown parameters in the Equation are the rheological parameters Eandη, linear rate v, and elevation correction ΔZ. 
 2ATE #OMPUTATIONS  $OPPLER FREQUENCY CALCULATION IS THE EASIEST WAY  TO FIND FADING RATES 4O COMPUTE THE SIGNAL AMPLITUDE RETURNED WITH A PARTICULAR RANGE OF DOPPLER SHIFTS  ALL SIGNALS HAVING SUCH SHIFTS MUST BE SUMME D 4HIS REQUIRES KNOW 
 RATE "  IN THIS CASE  INTERVALS IN POSITIVE AND NEGATIVE FREQUENCY 4HE SHEETS ARE STACKED ONE ON TOP OF THE OTHER AS SHOWN ON THE LEFT SIDE OF &IGURE  B  AND THE  RESULTING PORTION OF THE SAMPLED SIGNAL SPECTRUM FROM  TO THE SAMPLING RATE OF  " IS  GENERATED BY ADDING THE SPECTRA OF THE STACKED PAGES TOGETHER  AS SHOWN ON THE RIGHT  &)'52%   A  "ANDLIMITED  REAL SIGNAL SPECTRUM BEFORE SAMPLING   B  PORTION OF SAMPLED SPECTRUM  FROM  TO "  AND C  FULL SAMPLED SIGNAL SPECTRUM       
 Curve aofFig. 8.7represents schematically apolar diagram ofthe logarithm ofthe power recwived at thebeacon asafunction oftheangu- lar position ofthe radar antenna. The line tothe beacon isassumed tobethe upward vertical. 
 14.3.  I' was mentioned that the factor of 2 in the denominator of Eq. (14.4) was a consequence  of the relative phase shift between elements of the synthetic array antenna being due to the  two-way propagation path, instead of the one-way propagation path as in the conventional  array antenna. 
  
 Therefore, a comparison of the original proﬁle and the modiﬁed proﬁle is available. As a reference of the true measured electron proﬁle, ISR data was again adopted in the experiment to validate our proposed method. Despite doing our best, we only found one group of corresponding data, as shown in Table 2. 
 DOPPLER WAVE 
 THE 
 Theradartransmitter maybeoperated continuously ratherthanpulsedifthestrong transmitted signalcanbeseparated fromtheweakecho.Thereceived-echo-signal poweris cOllsiderahly smallerthanthetransmitter power;itmightbeaslittleas10-Itlthatofrhe transmitted power-sometimes evenless.Separate antennas fortransmission andreception helpsegregate theweakechofromthestrongleakagesignal,buttheisolation isusuallynot sufficient. Afeasibletechnique forseparating thereceived signalfromthetransmitted signal whenthereisrelativemotionbetween radarandtargetisbasedonrecognizing thechangein theecho-signal frequency causedbythedoppler effect. Itiswellknowninthefieldsofopticsandacoustics thatifeitherthesourceofoscillation ortheobserver oftheoscillation isinmotion,anapparent shiftinfrequency willresult.Thisis thedopplereffectandisthebasisofCWradar.IfRisthedistance fromtheradartotarget,the totalnumberofwavelengths). 
 The unique properties of these radars also make them of interest for  military applications. To illustrate the types of applications well suited for HF OTH radar,  two examples will be mentioned: air traffic control over the sea, and remote observation of  sea conditions.  In the continental United States and similar land areas of the world with large air traffic,  lotig-range microwave air-surveillance radars can keep track of aircraft for the purpose of  providing safe and efficient air travel. 
 INTERVAL RATIO 4HIS RESPONSE CURVE CONTINUES TO  66"    WITH NO DIPS BELOW  D" 4HE FIRST  BLIND SPEED IS AT 66"    .   -4) 2!$!2  Ó°{Î WHERE 2  2  2      2.  ARE THE SET OF INTEGERS AND  6" IS THE BLIND SPEED CORRESPOND 
 REFERENCES 1.Kovaly, J.J.:"Synthetic Aperture Radar," ArtechHouse,Inc.,Dedham, Mass.,1976.(Acolkction of 33reprints covering thedevelopment, theory,performance, effectoferrors,motioncompensation, processing, andapplication ofSAR.) 2.Cutrona, L.J.:Synthetic Aperture Radar;chap.23of"RadarHandbook," M.I.Skolnik (cd.). McGraw-Hill BookCompany, NewYork,1970. 3.Harger, R.0.:"Synthetic Aperture RadarSystems: Theory andDesign," Academic Press,New York,1970. 
 BAND APPLICATIONS v IN  )%%% -44 
 The design of an MTI to  detect moving targets in chaff is different from the design of an MTI for surface clutter since  the chaff is generally in motion. The MTI must be capable of coping with moving, rather than  stationary, clutter. In this regard the MTI design is more like that for detecting targets in  weather clutter. 
 TERING EDGE ELEMENT IS PERPENDICULAR TO THE LINE OF SIGHT 4HE AMPLITUDE OF THE DIFFRACTED FIELD IS GIVEN BY THE PRODUCT OF A  DIFFRACTION COEFFI 
 total effect of all other system components (To, system effective  noise temperature)2 34SNR (4 ) Tttr p r o BsnPGG G L P N RkBσλ π== Ts=TA+Te1/nBτ≈. 30Integration of Pulses • Noncoherent integration (postdetection integration ): performed after the envelope  detector.  The magnitudes of the returns from all pulses are added. 
 ( Reprinted  with permission of SciTech Publishing, Inc .55) ch14.indd   30 12/17/07   2:47:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 
 These noise sidelobes will not cancel in the MTI system and, if  suficiently large, they can result in uncancelled residue that will appear on the radar display.  Thus when the system instabilities are high, the detection of targets in clutter can be seriously  degraded. One approach for operating under such conditions is to use two limiters.39 One  limiter is placed before the pulse-compression filter and has an output dynamic range equal to  the difference between the peak transmitter power and transmitter noise in the system band-  width. 
 -(Z REGION IS IN MANY WAYS EASIER TO OPERATE THAN EQUIPMENT IN THE MICROWAVE REGION CERTAINLY IT IS MUCH EASIER TO OPERATE AND LESS EXPENSIVE THAN MICROWAVE EQUIPMENT OPERATING AT A  
 Although the Reggia-  Sperlcer phase stlifter tias beer1 successfully applied in operational radar and was one of the  first practical pli:~se stlifters sl~itilble for radar, in its present form it has been largely superseded  by other devices.  1,atching ferrite phase ~hifters.~'." The use of a ferrite in the form of a toroid centered withill a  waveguide as iri Fig. 8.10, results ill a phase sliifter with a fast switching time and with less  drive power than required of a Reggia-Spencer device. 
 Bernhardt, G. Ganguli, M. C. 
 MITTING A CODED WAVEFORM  WITH A LARGE VALUE OF THE TIME 
 and so forth. depending on the number of bits reqi~ired. A separate  pair of drive wires is used for each section of toroid. 
 FERENT FROM THOSE AT MORE MODERATE INCIDENCE ANGLES !LTHOUGH SOME SMALL REGIONS WITHOUT SIGNIFICANT PROJECTIONS OR FORWARD SLOPES MAY HAVE 2AYLEIGH DISTRIBUTIONS OR IF ONLY ONE LARGE SCATTERER IS PRESENT  2ICEAN DISTRIBUTIONS  MOST AREAS HAVE OTHER DISTRIBUTIONSOFTEN 7EIBULL OR EVEN LOG 
 - Finallyj variations inthe atmos- ~~ -\ pheric refractive index can cause ~~29/ large variations intheamount of ~~ radiation falling onthe gro~d or ~~10 water surface surrounding the *=: radar and thus appreciably change 10 thepattern.’ Despite these diffi- ~IO.6.19.—Typical elevation lobe pattern. culties, ifthere isplent yoffriendly airtraffic and ifradio contact can beused toenable acontinual check on height accuracy, adept radar plotters can give heights accurate towithin one thousand feet more than half thetime bythe observation ofsignal fades. The method isslow; areading cannot bemade inless time than that required foraplane toflythrough several nulls ofthepattern. 
 A. Secan, R. M. 
 W. Biggs: Radar Scatterometer Discrimination  of Sea-Ice Types, IEEE Trans., vol. GE-15, pp. 
 There exist in the  literature the necessary graphs and nomographs which simplify the computation of radar  coverage. 5 9 Computers may be used to perform the calculations and to automatically plot the  coverage patterns by computer-controlled plotting machines.1 ° Figure 12.4 illustrates, for a  particular case. the computed vertical-plane radar coverage patterns for (a) horizontal polari­ talion and (/,) vertical polarization. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 10.2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 of the radar’s capability. 
 Nitzberg, Radar Signal Processing and Adaptive Systems,  Chapter 7, Norwood, MA: Artech  House, Inc., 1999. 25. M. 
 Hahn, P. M., and S. D. 
 General Objectives.—The principal objectives can bestated simply as follows: Coverage was considered tobeimportant both astomaximum detection range and astothe altitude region included, but resolution in azimuth and inrange were thought tobeofcomparable importance. Where height information was desired, auxiliary height finders were tobe used; thus the radar beam could befixed inelevation and swept contin- uously inazimuth byrotation oftheantenna. Estimates ofdetailed requirements were difficult tomake inregard to characteristics such as(1)accuracy ofrange and bearing values asdeter- mined bymethods ofdata presentation, (2)interval between “looks” atthetarget asdetermined bytherevolutions perminute oftheantenna, and (3)traffic-handling capacity asdetermined bythenumber and type of indicators provided. 
 The final  section reviews several radar techniques that might be used to distinguish one class of target  from another.  11.2 INFORMATION AVAILABLE FROM A RADAR  A radar obtains information about a target by comparing the received echo signal with the  transmitted signal. The availability of an echo signal indicates the presence of a reflecting  target; but knowing a target is present is of little use by itself. 
 J.L.andG.E.Uhlenbeck (eds.):"Threshold Signals," MITRadiation Laboratory Series. vol.24,McGraw-Hili BookCompany, NewYork,1950,p.177. J.VanVlcek,J.B.,andD.Middleton: ATheoretical Comparison oftheVisual,Aural,andMeter Reception ofPulsedSignalsinthePresence ofNoise,J.Arr/.P1Jys.,vol.17,pp.940-971, November, 1946. 
 BEAM CLUTTER REGION  LOCATED AT F    62K COSX   CONTAINS THE STRONG RETURN FROM THE MAIN BEAM OF THE ANTENNA 4!",%  4YPICAL 6ALUES FOR AN 8 
 334-339, November, 1967.  60. Ruze, J., F. 
 (Alier B~oro\~s NII~ Attwo~d.~ colrrrrsy Acadtwic Press. lac.)  PROPAGATION OFRADAR WAVES457 compared withthecarth'sdimcnsions andlittlccnergyisdiffracted. Thusradarcovcragc cannotheextendcd muchbeyondthelineofsightbythismechanism. 
 , vol. 85, pp. 1871–1886, 2004. 
 Predrivers and a redundant preamplifier  were used as preceding drive stages. The power amplifier module consisted of ten identical silicon bipolar power tran - sistors arranged in a 2-driving-8 amplifier configuration to develop more than 2500 W  peak power output over the 400 to 450 MHz frequency bandwidth. Each transistor was  a 400 W peak-power device that was operated in a balanced push-pull circuit design. 
 130 INTRODUCTION TO RADAR SYSTEMS  power. Two radars with the same subclutter visibility might not have the same ability to  detect targets in clutter if the resolution cell of one is greater than the other and accepts a  greater clutter signal power; that is, both radars might reduce the clutter power equally,  but one starts with greater clutter power because its resolution cell is greater and .. sees"  more clutter targets. 
 The frequency does not enter explicitly. Since it is easier mechanically to move a small antenna than a large one, tracking radars are usually found at the higher frequencies, where small apertures can have high gain and thus an adequate G, Ae product. The radar equation is based on detectability. 
 VI due to the higher levels of sea return than for ASV Mk. III. In [ 17] in March 1944, trials of a discrimina tor circuit were undertaken for ASV Mks VA, III and VI (see chapter 3for discussion on ASV Mk. 
 FIG. 7  FIG. 8  Now look at the ‘long’ pulse (Fig. 
 +1 
 The second is the phase error due to the di ﬀerence in phase distortion of the SAR image pair used for the interference. In this section, we analyze the impact of the above two phase errors on DEM accuracy. Since the application background of the interferometric ArcSAR in this paper is deformation monitoring, the deformation monitoring accuracy is also analyzed. 
   '2/5.$ 0%.%42!4).' 2!$!2   Ó£°£Î 7HERE INTERFACES ARE SPACED MORE CLOSELY THAN ONE HALF WAVELENGTH  THE REFLECTED  SIGNAL FROM ONE INTERFACE WILL BECOME DIFFICULT TO RESOLVE WITH THAT FROM ANOTHER )T SHOULD BE NOTED THAT THE NORMAL RADAR CRITERIA FOR RANGE RESOLUTION IS LESS APPROPRI 
 HORIZON /4(  RADAR IS DESCRIBED IN !BRAMOVICH ET AL  -ONOPULSE RADARS THAT USE PARABOLIC REFLECTOR ANTENNAS ARE SUSCEPTIBLE TO JAMMING  THROUGH CROSS 
 (a) Sqllare iromrore dcflcrti(, nc,,il inca.c. (},,S{,u:,re ire,,.r,jr[> dc.fle,tion coil. (c,.Ii,-cure deflection (coil for off-center PPI, u.cd ine,J[liwl[tion ~!ith (<II. 
 SURFACE SCATTERING MODELS WITH SPECULAR REFLECTION AT VERTICAL INCIDENCE  AND A SMOOTH CURVE IS DRAWN BETWEEN THE SPECULAR VALUE AND THE ROUGH 
 Thus, over the entire  CIT, a sequence of phase shifts is applied, that is, a modulation, which is imposed on  the received signal. As a consequence, the strong clutter echoes are spread in doppler,  masking targets. To overcome this problem, Abramovich et al.139 developed a tech - nique known as the method of stochastic constraints,  which uses different rules for  weight adjustment, preserving not only the gain but also, to a good approximation, the  phase of the clutter received via the main beam response. 
 Adequate filtering and shielding are provided todeal with any ordinary problems ofmutual interference between the radar and other electronic equipment installed inthe same aircraft. The transmitter-receiver isprotected against changes inexternal pressure bymeans ofarubber-gasket seal and pressure-tight cable connectors. The r-fline isalso sealed and isconnected toapressure pump with adryer oriitsintake. 
 K. Fung and R. K. 
 POLAR POWERS IN  ADDITION TO THE SOLAR FLUX  AN ACCURATE ESTIMATE OF THE DIFFERENTIAL CHANNEL CALIBRA 
 FREQUENCY ANALYSIS TECHNIQUES v  )%% 0ROC 2ADAR  3ONAR  AND .AVIGATION   VOL    PP n  &EBRUARY   ' * &RAZER AND 3 * !NDERSON  h%STIMATING THE FREQUENCY INTERVAL OF A REGULARLY SPACED MULTI 
 C. Shelton, “Power spectral lineshapes of microwave radiation backscattered from sea  surfaces at small grazing angles,” IEE Proc.-Radar, Sonar Navig ., vol. 142, no. 
 In a two-dimensional array, the most serious random error is in the translational position  of the dipole elements. Of secondary importance are the errors in the currents applied to the  elements. The angular position of the dipole elements is relatively unimportant. 
 Noise that accompanies the local-oscillator (LO) signal can appear at the IF  frequency because of the nonlinear action of the mixer. The LO noise must be removed if  receiver sensitivity is to be maximized. One method for eliminating LO noise that interferes  with the desired signal is to insert a narrow-bandpass RF filter between the local oscillator and  the mixer. 
 BEAM AZIMUTH ANGLE RELATIVE TO THE HORIZONTAL VELOCITY  RADIANS  S   COMPRESSED PULSE WIDTH  H   RADAR ALTITUDE 7HEN THE MAGNITUDE OF THE MAIN 
 It was noted that the ease of homing onto beacons was similar to ASV Mk II but that homing onto IFF Mk. III was dif ﬁcult due to the short response, occurring only every 2 ½ s. Unlocked interference from ASV Mk. 
 OUTPUT VOLTAGE 4HE BEAT FREQUENCY IS A SMALL FR ACTION OF ONE (Z AND IS  BETTER VISUALIZED AS A PHASE RATE BETWEEN THE TRANSMIT PULSE CYCLE AND CYCLE OF THE RANGE  GATE 4HE CHANGING PHASE CAUSES THE RANGE GATE TO FOLLOW A MOVING TARGET 4HE ELECTRONIC RANGE TRACKER IS INERTIALESS  ALLOWING ANY DESIRED SLEW SPEED  AND PRO 
 Since there isnofeedback solong asV6 isbeyond cutoff, itsgrid isele- vated very rapidly atthebeginning ofthesawtooth and there isthus no appreciable delay before thecurrent starts. The deflecting coil isrotated byamechanical repeater such asthose described inSec. 13“5. 
 The two-dinie~isional planar array is probably the array of most interest in radar applica-  tions since it is fundamentally the most versatile of all radar antennas. A rectangular aperture  can produce a fan-shaped beani. A square or a circular aperture produces a pencil beam. 
 Such a circuit is used for the  strobe. Signal pulses are applied to the control grid,  and strobe pulses to the suppressor. The only output at  the anode, if the valve is correctly biased, is that which  coincides with the strobing. 
 Inso defining thepulse length, itisnecessary toignore arather short-duration, high-current spike often found ontheleading edge ofthe current wave. Sodefined, TOcan beused satisfactorily incalculations ofaverage current and average r-fpower. Successful pulsers have been designed and put into production forTOasshort as0.1psec, and aslong as5usec oralittle more. 
 Modern radar systems can take advantage of on- and off-board cues to increase  the probability of acquiring a target using Cued Search. A Cued Search mode adjusts  the search volume and waveform selection according to the accuracy of the cue’s  parameters. Radars with electronically scanned array (ESA) antennas can interleave other func - tions (track updates, Cued Search, calibrations, etc.) with Autonomous Search. 
 IEEE Tru~rs., vol. AES-3, no. 6  (EASTCON Suppl.), pp. 
 WAVE EVENTS WILL CONTRIBUTE IMPORTANTLY TO SEA CLUTTER OVER  MOST OF THE hROUGH SURFACEv REGIME OF GRAZ 
 Limiting Amplitude Uniformity.  No single-stage limiter will exhibit a constant  output over a wide range of input signal amplitudes. One cause is apparent if one  considers the effect of a single-stage limiter having a perfectly symmetrical clipping at  voltages ±E. 
 Sub tractor Amplifier Det.Full-wave rectifierAutomati c balancing circuitsTiming contro l voltage Pilot Pulse AGC Delayed chan nel Direct chann elCanceled unipolar videoPRF trigger to rada r syste m Bipola r video   Figure 8.11  Block diagram of a Delay Line Canceller.   8.6 Filterbank Procedure   Here, identified as the filterbank analysis procedure, digital signal processing was quickly d e- volved and put to use.  Range and Doppler frequency regions are divided into sub -regions,  which are processed separately. 
 SITE  REGION ARE THE  -ANASTASH 2IDGE 2ADAR  OPERATING WITH AN &- BROADCAST TRANSMITTER FOR  TROPOSPHERIC SOUNDINGS    3ILENT 3ENTRY OPERATING WITH &- AND 46 BROADCAST TRANS 
 This time corresponds in the conical-scan tracker to  at least one revolutiorl of the antenna beam. With lobe switching, the minimum time is that  necessary to obtain echoes at the four successive angular positions. In either case four pulse-  repetition periods are required to make a measurement; in practice, many more than four are  often used. 
 Aperture blocking by the subreflector is reduced with  this design.  Minimum total aperture blocking occurs when the shadows produced by the subrdlector and  the feed are of equal area.19 Aperture blocking is less serious with narrow beamwidths and  small fl D ratios.  If operation with a single polarization is permissible, the technique diagramed in Fig. 
 Methods for TEC Retrieval and T opside Proﬁle Modiﬁcation We ﬁrst present the methods used in this paper for retrieving TEC from PolSAR data, and then introduce the algorithm for improving the topside proﬁle of ionosonde with the retrieved TEC.2.1. TEC Retrieval from PolSAR Radar signals at the L band and lower frequencies will suffer strong Faraday rotation (FR) effects when they pass the ionosphere. However, these FR effects could serve as useful information for deriving the total electron density along the signal propagation path. 
 37, pp. 608-615, April, 1965.  29. 
 Sucll a high-duty factor radar is sometinles called  i~lrer.r.rr/~ft~d C'IY, or ICW.  Noncoherent Ahl'I'i. The norlcollerent MTI principle that uses the clutter echo instead of a  col~o as the reference signal cat1 also be applied to a radar on a moving platform. 
 ARRAY FEEDS AND  CLUSTER FEEDS v )%%% 4RANS !NTENNAS 0ROPAGAT   VOL   NO   *ANUARY   2 & (ARRINGTON   4IME (ARMONIC %LECTROMAGNETIC &IELDS   .EW 9ORK -C'RAW 
 However, these studies do not provide re- sults for SBR surveillance sensors that must detect tar- gets in clutter. These sensors typically have a nadir hole 20 to 30° off nadir in which the signal-to-clutter ra- tio (SCR) is too large for reliable detection. This is shown in Fig. 
 JAM RATIO CAN BE VERY UNFAVORABLE !NTENNA JAMMER NULLING IS USUALLY REQUIRED SINCE TRANSMITTING MORE POWER TO BURN THROUGH MAY NOT BE POSSIBLE #LEARLY  THE DATA FROM AND TO A WEAPON MUST ALSO BE SUFFICIENTLY ENCRYPTED TO PREVENT TAKE 
 Remote Sens. Lett. 2013 ,10, 1562–1566. 
 The abscissa can also be interpreted as the ratio of the target doppler fre - quency to the average PRF of the radar. The canceler configurations shown are not the most general feedforward, feedback  networks possible. Pairs of delays are required to locate zeros and poles elsewhere FIGURE 2.36  Three-delay canceler ch02.indd   37 12/21/07   10:16:14 AMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 MOUNTED  '(Z RADAR 3ECOND  ITS PERFORMANCE IN SEA CLUTTER WILL BE ENHANCED  AS THE GRAZING ANGLE TO THE SEA WILL BE CLOSER TO HORIZONTAL  THEREBY LESSENING THE REFLECTION COEFFICIENT OF THE CLUTTER 4HE LONG RANGE PERFORMANCE OF THE AUXILIARY SYSTEM IS  OF COURSE  COMPROMISED BY ITS LOW POSITION -OVING 0LATFORM  ! PARTICULAR COMPLICATION OF SHIPBORNE RADAR ARISES BECAUSE  THE ANTENNA IS MOUNTED ON AN UNSTABLE MOVING PLATFORM 4HIS MOVEMENT HAS SIX COMPONENTSTHREE TRANSLATIONAL AND THREE ROTATIONAL  ALL OF WHICH ARE TYPICALLY VARYING 4HE MOTIONS ARE COMPLEX THE TRANSLATIONAL COMPONENTS ARE SURGE  SWAY  AND HEAVE  AND THE ROTATIONAL ARE ROLL  PITCH  AND YAW #OMPONENTS CAN BE QUASI 
 J., E. N. Leith, C. 
 In an RAC, the input and output transducers have a broad bandwidth. A frequency-sensitive grating is etched on the crystal surface to re- flect a portion of the surf ace-wave signal to the output transducer. This grating coupling does not have a significant impact on the surface-wave energy. 
 WIDEBAND 3!2  PRESENTS CHALLENGES  IN DESIGNING HARDWARE COMPONENTS  SUCH AS ANTENNAS  THAT ARE REASONABLY LINEAR OVER THE FULL FREQUENCY RANGE  &URTHERMORE  THE LONG APERTURE TIME PRESENTS MOTION 
 3)4 INTRODUCTION TO RADAR SYSTEMS  The low crossover level of the Butler array is one of its disadvantages. If a lossless network  could be achieved with a cosine illumination so as to reduce the sidelobe levels compared to  those obtained with a uniform illumination, the crossover level would be even worse (a level of  -9.5 dB).  By combining the output beams of the networks with additional circuitry, the Butler  beam-forming network can be modified to obtain aperture illuminations that result in lower  sidelobes than available with uniform illumination. 
 M. Skolnik, Introduction to Radar Systems , 3rd Ed., New York: McGraw-Hill, 2002, pp. 662, 663. 
 2AYLEIGH DENSITY  WHERE THE LOG OF THE RETURN HAS A GAUSSIAN DENSITY  IS SHOWN IN &IGURE  4HE OPTIMAL BINARY INTEGRATOR IS MUCH BETTER THAN THE MOVING 
 3. D. Eliot (ed.), Handbook of Digital Signal Processing , San Diego, CA: Academic Press, 1987,  pp. 
 A log (logarithmic) receiver is a device whose video output is proportional to the logarithm of the envelope of the RF input signal over a specified range. It is useful in preventing receiver saturation in the presence of variable intensities of jamming noise, rain, clutter, and chaff. Log receivers have the ECCM advantage of permitting the radar receiver to detect target returns that are larger than jam- ming noise, chaff, or clutter levels. 
 Any use is subject to the Terms of Use as given at the website. Sea Clutter.  SEA CLUTTER  15.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 15.2 THE SEA SURFACE Close observation of the sea surface discloses a variety of features describable as  wedges, cusps, waves, foam, turbulence, and spray, as well as breaking events of all  sizes and masses of falling water. Any or all of these might contribute to the scatter - ing of electromagnetic waves responsible for sea clutter. 
 1021, provides atuning range ashigh as12 percent, Atfrequencies lower than about 5000 Me/see, the magnitude ofthe longitudinal displacement required ininductive tuning becomes incon- venient, and other tuning methods areadopted. Figure 10.22 sho!vs a “C-ring” type oftunable magnetron, inwhich aconducting surface can bemoved toward oraway from the straps and capacitive portion ofthe resonant cavities, thus changing their effective capacity. The disad-. 
 Ronconi, and S. Sabatini, “Some phased-array  systems and technologies in AMS,” IEEE Int. Symp. 
 VH and  HV represent cross•polarized components.  (From Olin and Queen.30) . i ,/ In!  I  ~-:: 1)" !  !=,~F~I ?P  '" ""1r1  ,,, ~( I ---·  0 0 ·~.,:::·::::::-::=·----·----~~;~  ' ------- ,1 -1nn"  '.o ·-j -'1('  (t,) fll",<111r"1n,;prrlo11'1t"{drfll (r.l THE RADAR EQUATION 43  Figure 2.20 Same as Fig. 
 A typical form, after Blass,36 is shown in Fig. 1 .Id. The geometry can be adjusted to provide equal path lengths, thus providing frequency-independent time-delay scanning. 
 Stabilized Magnetrons. The most common form of stabilized magnetron is the coaxial magnetron, in which a high-g annular cavity is intimately coupled to the anode vanes inside the inner cylinder, as shown in Fig. 4.4. 
 The velocity of propagation of electromagnetic waves in free space is  approximately 3 × 108 ms–1 but slows in a material depending on its relative permittiv - ity and relative magnetic permeability. The velocity of propagation of electromagnetic  waves in a soil with a value for er of 9 would be slowed to 1 × 108 ms–1. The time to a  target at a range of 1 meter is, therefore, 20 ns, and GPR systems operate at time ranges  between a few nanoseconds up to 200 ns, although some systems for probing through  ice may use ranges up to several tens of milliseconds. 
 ~ame array over more than one frequency region is of advantage when mutual interference  between radars is of concern. It can also be of importance for military applications in which  frequency diversity is desired.  Equation (8.18) assumed a transmission line whose velocity of propagation was that or  the velocity of light. 
 73, pp. 284–289, February 1985. 55. 
 The altitude of the F2 region peak lies  typically between 250 and 350 km at middle latitudes. The F2-region ionization shows  marked day-to-day variations and, in general, is not the regular sun follower that the  E and F1 regions are. The simple physical picture of the ionosphere as consisting of several more or less  concentric layers must be modified substantially at both low and high latitudes to  take into account the effects of the impressed electric and magnetic fields. 
 #7 CASE  IT IS NOT GENERALLY FEASIBLE TO SYNTHESIZE SUITABLE PULSE WAVEFORMS FROM SEPARATE SUBBANDS OF THE (& SPECTRUM WHEN WIDE CLEAR CHANNELS ARE NOT AVAILABLE &IFTH  THERE ARE FE WER OPTIONS FOR RADI 
 The scanning limitation does not apply to a system that can step-scan, such as  a phased array. Note, however, that sufficient pulses must be transmitted to initial - ize the filter before useful outputs may be obtained. For example, with a three-pulse  binomial-weight canceler, the first two transmitted pulses initialize the canceler, and a  useful output is not available until after the third pulse has been transmitted. 
 5.16  Transceiver Module Performance  Characteristics  ................................................  5.18  5.4 Transmitter System Design  ....................................  5.21  Performance Sensitivities  .................................. 
 DOMAIN WEIGHTING IS UTILIZED IN THE SPECTRAL ANALYSIS PROCESSING TO REDUCE  THE TIME SIDELOBES OF THE COMPRESSED PULSE AND IMPROVE THE RESOLUTION PERFORMANCE  WHEN MULTIPLE TARGETS ARE PRESENT WITHIN THE RANGE WINDOW !S AN EXAMPLE  THE USE OF (AMMING TIME 
 OUT CORRUPTION BY  ALIASING  THE OVERLAPPING OF SPECTRAL COMPONENTS 4HE BOUND  TERMED  THE .YQUIST FREQUENCY OR  .YQUIST RATE  IS EQUAL TO THE TWO 
 A single horn, combined with a properly located ground  plane, can also generate a cosecant-squared pattern with a parabolic reflector.91 The feed  horn, plus its image in the ground plane, has the same effect as two horns. The traveling-wave  slot antenna92 and the surface-wave antenna93 can also he designed to produce a cosecant­ squared antenna pattern.  The shaping of the beam is generally in one plane, with a narrow pattern of conventional . 
 716–723,  June 1974. 34. G. 
 BANDWIDTH PRODUCT  4HE PEAK TIME SIDELOBE LEVEL OF THE COMPRESSED PULSE IS n D"  !S DISCUSSED IN 3ECTION   A FREQUENCY 
 The off-nadir* look angle of certain SBRs  can be adjusted to increase the effective revisit rate. Note that orbit maneuvers are not  a practical means to improve the frequency of site coverage, since a large change in  altitude (hence velocity), or especially any change of orbit inclination (the angle of  the inertial orbit plane with respect to the Earth’s equator), would require a substantial  expenditure of precious onboard fuel resources.3 The Earth is flattened at the poles, due primarily to its relatively rapid rotation. The  resulting lack of spherical symmetry in the gravity field at orbital altitude imposes  small lateral forces on an inclined orbit plane, which consequently precesses in inertial  space. 
 REFERENCES  1. Dunn, J. H., D. 
 It is defined as the bistatic radar’s benchmark range .  Since this benchmark is geometry-invariant, it becomes useful when comparing  bistatic to monostatic range performance. Finally, an oval of Cassini is established  as a function of the baseline range, L, normalized to the benchmark range, RM. 
 depicted in Fig. 6.12 is called ree11tra11t, in that the electrons that are not  collected after energy is extracted at the output port are permitted to reenter the RF interac­ tion area at the input. This improves the efficiency of the tube. 
 Mem. 560,  Aug. I, 1957, Culver City, Calif. 
 3URFACE -ISSION 0ROFILE  4HE MODE STRUCTURE OF ANY MODERN FIGHTER AIR 
 Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 5.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 The fusion of the recognition of each of the signatures above provides excellent  noncooperative recognition. Weather Avoidance. 
 Borner, T.; Papathanassiou, K.P .; Marquart, N.; Zink, M.; Meadows, P .J.; Rye, A.J.; Wright, P .; Meininger, M.; Tell, B.R.; Traver, I.N. ALOS PALSAR products veriﬁcation. In Proceedings of the 2007 IEEE International Geoscience and Remote Sensing Symposium, Barcelon, Spain, 23–28 July 2007; pp. 
 32. H. E. 
 TIVE PROCESSING 3!0  REDUCES THIS PROBLEM BY ADJUSTING THE AMPLITUDE AND PHASE OF THE SAMPLED RECEIVER OUTPUTS IN  SUCH A WAY AS TO MINIMIZE THE INTEGRATED NOISE POWER  LEAKAGE  WHILE PRESERVING THE GAINSENSITIVITY OF THE BEAM BEING SYNTHESIZED &IGURE  COMPARES CONVENTIONAL PROCESSING AND 3!0 APPLIED TO THE SAME BLOCK  OF RADAR DATA ! REDUCTION OF SOME  D" IS ACHIEVED IN THIS EXAMPLE  WHERE NOISE  NOT CLUTTER  IS THE PROBLEM 4HE PATTERN HERE HAS ADAPTED TO MINIMIZE THE TOTAL ENERGY COLLECTED IN THE DOPPLER BANDS ;n n= (Z AND ; = (Z  WHILST MAINTAINING THE ARRAY  &)'52%   #OMPARISON OF DOPPLER SPECTRA ESTIMATED BY I  CONVENTIONAL BEAM 
 SANDWICH BECAUSE OF THE RELATIVELY DENSE CORE 4HE " 
 Based on the imaging geometry in Figure 1a, data acquired with the same azimuth squint angle on each pass can be combined and processed for 3D imaging, which is similar to the traditional TomoSAR. Moreover, the data acquired with di ﬀerent azimuth squint angles on each pass can be selected and used to suppress azimuth sidelobes. However, the acquisition of the data should meet the imaging 40. 
 Performance chart and Rieke diagram. Four parameters determine the operation of the  magnetron. l'hese are ( l) the magnetic field, (2) the anode current, (3) load conductance, and  Figure 6.5 Photograph of the SFD-319 K0- band fixed frequency inverted coaxial magnet­ ron. 
 DOPPLER     2OSENBERG AND 'RAY  TACKLE THE PROBLEM OF MITIGATING THE EFFECTS OF AN AIRBORNE  BROADBAND JAMMER PRESENT IN THE MAIN BEAM OF A 3!2 )N ADDITION TO THIS  MUL 
 If,onthe other hand, the uolfuge across the plate load isofinterest, acathode resistor gives the proper type offeedback only ifthe load isalso purely resistive. If 1Ifapentode orbeam-power tube isused, thescreen current passes through the cathode resistor butnotthrough theload. Invery exacting cases some account must betaken ofthisfact.. 
 To estimate the noise level of the RCS curve, the high scatterings should be removed. The energy concentration parameter W is defined as an approximation for the target high scattering persistence angle by Zhao et al. [ 25]. 
 Following this, the circumferential velocity Vθcan be computed as Vθ=Γ0 2πr/bracketleftbigg 1−exp(−αr2 4υ)/bracketrightbigg (10) According to the above derivation, the three-dimensional velocity ﬁeld of the vortex in the cylindrical coordinate system is given by Equations (8)–(10). Transform Equations (9) and (10) into the Cartesian rectangular coordinate, and the vortex velocity ﬁeld can be expressed as Vx=−α 2x−Γ0α 8πυy Vy=Γ0α 8πυx−α 2y(11) where Vxis the component of the velocity ﬁeld in the xdirection, and Vyis the component of the velocity ﬁeld in the ydirection. Therefore, by setting the parameter values of αandΓ0, different two-dimensional current ﬁelds of vortex can be obtained according to Equation (11). 
 iis it would if it were generated by a conventional meclia~iically  scanned antenna, extraneous hits frorn adjacent beam positions can be readily recognized as  such. Ari operator viewing a I'f'l woulcl have no problem. However, in a flexible phased-array  radar, the sciinriirig of the beat11 positions niight riot be uniform. 
 Timmoneri, “Parallel processing architectures for STAP,” in Applications of  Space-Time Adaptive Processing , R. Klemm (ed.), London, UK, IEE Radar, Sonar and Navigation  Series 14, 2004, pp. 265–302. 
 RANGE DISPLAY SHOWN IN THE LOWER RIGHT OF &IGURE   4HE  TERRAIN AVOIDANCE SCAN PATTERN SHOWS ALL THE TERRAIN THAT IS NEAR OR ABOVE THE FLIGHT ALTITUDE AND ONE CUT BELOW AT A SET CLEARANCE ALTITUDE  FT TYPICALLY   &IGURE   LOWER LEFT AND LOWER RIGHT  SHOWS THE SITUATION GEOMETRY OF AN AIRCRAFT FLYING TOWARD TWO HILLS AND THE CORRESPONDING ALTITUDE CUTS DISPLAYED TO THE  PILOT 4HIS ALLOWS EITHER  MANUAL OR AUTOMATIC TURNING FLIGHT TO MAINTAIN A LOWER ALTITUDE 4&4! ALLOWS AN AIRCRAFT TO PENETRATE AT LOW ALTITUDE USING THE TERRAIN AS MASKING   THUS PREVENTING EARLY DETECTION 4&4! IS AN IMPORTANT ASPECT OF STEALTH EVEN WHEN THE ALTITUDE IS NOT ALL THAT LOW BECAUSE LOWER ALTITUDES PROVIDE SOME TERRAIN OBSCURATION AND MANY OTHER COMPETING TARGETS WITH SIMILAR CROSS 
 (7.14). The aperture distribution becomes  1 00 ("A.) ( j2rcnz) As(z) = d n=~oo Es d exp --d- (7.27) . RADAR ANTENNAS 257  Therefore the aperture distribution which generates the 11th (sin t/J)N composing pattern has  uniform amplitude and is proportional to the sampled value £5(11)./d). 
 Alternatively we can use, say, electrostatic deflection  in the Y direction, and magnetic deflection in the X  direction to produce the regular beat of the time-base  display.  Where we have two pairs of electrostatic plates it is  common in a badly adjusted tube to find evidence of  . 68 HOW RADAR WORKS  ‘trapezium distortion,’ a name arising from the trape-  zium-shaped figure which can, in extreme cases, result  from this distortion. 
 Then the radar-tracking point will move to  the other aircraft. The dwell on each target with random switching between the two  aircraft causes the double-humped distribution of error. Range Measurement Errors. 
   
 Van Meter, D., and D. Middleton: Modern Statistical Approaches to Reception in Communication  Theory, IRE Trans., no. PGIT-4, pp. 
  
 H. K. Weickmann and H. 
 MEDIUM  OR HIGH !LSO  MODERN MULTI 
 MIZE THE EFFECT OF BACK AND SIDELOBES FROM THE FEED ANTENNA  WHICH CAN EASILY GENERATE REFLECTION FROM THE GROUND SURFACE /NE METHOD OF RADIATING CIRCULAR POLARIZATION IS TO USE AN EQUI 
 Height finding is accomplished by interpolating the re- ceived signal strengths in adjacent elevation beams of the stack to determine the target elevation angle. The array is 10.6 m high by 6.1 m wide and consists of 60 center-fed rows of 32 radiating elements, each equipped with 60 receivers to downconvert received RF to IF. The azimuth beam is 2.8° wide. 
 On the reception side a low -noise pre- amplifier (LNA) is built in.  The IF signal is converted to bas e- band with an I/Q demodulator.  Typical IF frequencies are anywhere between 500  kHz and  10,7 MHz. 
 The MT1 photograph inFig. 16.1 shows everything incorrect adjustment sothat theresidue ofthe clutter blends with the noise. The corresponding photograph inFig. 
 TIVELY WIDELY SPACED 732 
 It is cheap and strong but is relatively  difficult to form. Stainless steel or plastic coated galvanized steel are used when the surface:  must be resistant to corrosion. Aluminum is light in weight but is more expensive than steel. 
 LOOKv )N JARGON COMMON IN THE SPACE 
 Next were designed relatively narrow-beam, continuously scan- ning radars, inwhich each target inthefield ofview isdisplayed period- ically, sothat itsazimuth and range can beread offatregular intervals. Afurther step was made with thedevelopment oftheplan-position indi- cator, orPPI, which, although theradar beam was still narrow and still 1Since theradar design oftheSCR-270 does notdiffer from that oftheSCR-271, thedesignation SCR-270 willbeused, asamatter ofconvenience, tostand foreither equipment. ~FfyL.N.Ridenour.. 
 Also this c-w system will measure such short ranges much more accurately than pulse systems. Orsuppose the velocity of abullet iswanted-the system described inSec. 56 measures such quantities easily and directly. 
 [ CrossRef ] [PubMed ] 21. Szegedy, C.; Toshev, A.; Erhan, D. Deep neural networks for object detection. 
 em8Figure13.13One-way attenuation (0BI km)inrainatatemperature of l8°C(0)Drizzle- 0.25mmlh;(h)light rain--l mm/h;(c)moderate rain-4 mm/h:(d)heavyrain-16 mm/h;(e) excessive rain-40mm/h.InWashing­ ton.D,C,arainfall rateof0,25 mm/hisexceeded 4','1h1yr.1mm/his exceeded 200h/yr..1mm/hisexceeded 91060h/yr.16mm/hisexceeded 8h/yrand 40mm/I!il'xceeded 22Iyr.. 504 INTROD~JCTION TO RADAR SYSTEMS  13.8 DETECTION OF TARGETS IN PRECIPITATION  The chief effect of weather on radar performance is the backscatter,or clutter, from precipita-  tion within the radar resolution cell. Attenuation by precipitation usually has little effect on  the detection of targets except at frequencies above X band. 
 on Radar Meteorol. , AMS, Seattle, 2003   pp. 727–729. 
 DOPPLER CLUTTER 4HE VERTICAL  RADIATION PATTERN CON 
 TRACKING LOOP IS CLOSED BY USING THE RANGE 
 xxviii     Contents   Antenna  .............................................................  19.33  Receiver  ............................................................  19.35 Low-Noise Frequency Reference  ....................... 
 AND ODD 
 OF 
 155–162, April 1981. 10. F. 
 This unit serves asacable junction box, and itsuseinthis capacity hasenabled thesettobedesigned with a total ofonly seven cables. Since the circuits aredesigned toallow for cable capacitance and forvoltage drops, any ofthese cables can beas long as25ft. Separation ofthe synchronizer power-supply unit from the synchronizer itself permits the latter tobesmall enough tobecon- veniently used asthe main control box. 
 DELAY CIRCUITS GIVING A WIDE INSTANTANEOUS BANDWIDTH 3ECTION   4HE SIMPLE METHOD OF PROVIDING 42 TRANSMIT 
 Operating at more than one KF  frequency can also reduce the effect of blind speeds.  108INTRODUCTION TORADAR SYSTEMS Blindspeeds.Theresponse ofthesingle-delay-line canceler willbezerowhenever theargu­ mentrrJjTintheamplitude factorofEq.(4.6)is0,n,2n,...,etc.,orwhen (4.7) where II=0,1,2,...,andj~=pulserepetition frequency. Thedelay-line cancela notonly eliminates thed-ccomponent causedbyclutter(n=0),butunfortunately italsorejectsany moving targetwhosedoppler frequency happens tobethesameastheprforamultiple thereof. 
 PASS LIMITER IS SINUSOIDAL  WHEREAS THE OUTPUT WAVEFORM FROM A BROADBAND LIMITER APPROACHES A SQUARE WAVE $EVIATIONS FROM THE IDEAL CHARACTERISTICS CAN DEGRADE RADAR PERFORMANCE IN A VARIETY OF WAYS ,INEARITY "ELOW ,IMITING  /NE MAJOR DRAWBACK OF ADDING A LIMITER STAGE TO A  RECEIVER CHANNEL IS THAT IT IS INHERENTLY NONLINEAR 3INCE ANY PRACTICAL LIMITER HAS A GRADUAL TRANSITION INTO LIMITING  THE LIMITER IS OFTEN THE LARGEST CONTRIBUTOR TO RECEIVER CHANNEL NONLINEARITY IN THE LINEAR OPERATING REGION AND CAN CAUSE SIGNIFICANT INTER 
 ATES ARTIFICIAL GLINT INTO THE MONOPULSE TRACKING LOOP 4HE INVENTORS OF THE CROSS 
 This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). 199. sensors Article Improving the T opside Proﬁle of Ionosonde with TEC Retrieved from Spaceborne Polarimetric SAR Cheng Wang1,*, Wulong Guo1, Haisheng Zhao2, Liang Chen1, Yiwen Wei3and Yuanyuan Zhang3 1Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, Haidian district, Beijing 100094, China; guo.wulong@163.com (W.G.); chenliang@qxslab.cn (L.C.) 2National Key Laboratory of Electromagnetic Environment, China Research Institute of Radiowave Propagation, Qingdao 266107, China; zhaohaisheng213@163.com 3School of Physics and Optoelectronic Engineering, Xidian University, Xi’an 710071, China; ywwei@xidian.edu.cn (Y.W.); yyzhang1@xidian.edu.cn (Y.Z.) *Correspondence: solskjaer2006@126.com; Tel.: +86-186-1815-4639 Received: 14 December 2018; Accepted: 23 January 2019; Published: 26 January 2019/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: Signals from spaceborne polarimetric synthetic aperture radar will suffer from Faraday rotations when they propagate through the ionosphere, especially those at L-band or lower frequencies, such as signals from the Phased Array type L-band Synthetic Aperture Radar (PALSAR). 
 A responsive  jammer could measure the frequency of the first transmitted pulse and then center the  jammer to spot-jam the following pulses. Also, the requirement for a stable PRF pre - cludes the use of pulse-to-pulse jitter, which is one of the most effective techniques  against deception jammers that rely on anticipating the radar transmitter pulse. Coherent  doppler processors are also generally vulnerable to impulsive radio frequency interfer - ence, especially in radars with a limited number of coherent bursts on target.147 Another ECCM technique to be considered is pulse compression by matched  filtering; it is intimately related to the waveform coding discussed in Section 24.7. 
 The twoinputstothemultiplier arethereceived echosignaly(t)andagatingsignalg(t-TR).The timeTR=2R/cistheestimate ofthetruedelaytimeTo.Thepurpose ofthegatingsignalisto aidinextracting anesimateofTo.Asbefore,itisassumed thatthesignalislargecompared withnoise;consequently thereisnodoubtastotheexistence ortheapproximate position of theechopulse. yU) MultiplierLow-pass filter (integrotor)Output )0 Figure11.2Receiver formeasuring range(limedelay) usingagatingsignalg(t-TR).whereTRistheestimate ofthetruetimedelay.Notethesimilarity tothecross­ correlation receiverofFig.10.3.. EXI'HACTION OF INFORMATION AND WAVEFORM DESIGN 403  The echo signal y(t) is composed of signal and noise, s(t - To) + n(t), where s(t - To) is  the echo signal in the absence of noise. 
 the beam is steerable. The generation of multiple fixed beams or a nun~ber of  inclependent steerable beams requires a duplication of the sampling pulse generators anti  sampling mixers.  Other beam-forming methods. 
 Lombardo, “SAR ECCM using adaptive antennas,” Proc. of IEEE Long Island  Section, Adaptive Antenna Systems Symp ., Long Island, USA, November 1994, pp. 79–84. 
 The field strength atsome other point Bofheight h~can bedescribed bygiving the ratioofthe field strength atthat point tothe field strength which would have been observed inthe absence ofthe reflecting surfacein. 48 THERADAR EQUATION [SEC. 212 other words, under free-space conditions. 
 The background is spotlight SAR image, and the segmented portion is forward-looking and backward-looking images.   Figure 17. A multi-angle fusion result of a large scenario area. 
 King: Measurement of the Radar Cross Section or a Man, Proc.  IRE, vol. 46, pp. 
 GUIDE FORMED BY THE %ARTH AND THE IONOSPHERE ! DESCRIPTION OF WAVEGUIDE MODELS IS BEYOND THE SCOPE OF THIS CHAPTER BUT MAY BE FOUND IN A PUBLICATION BY "UDDEN . 
 In the noncooperative transmitter column, if a noncooperative transmitter and a  hitchhiker were located in or near a battle area, a hitchhiker could use that transmitter  in the co-site region just as it would for a cooperative transmitter. The German Klein  Heidelberg  hitchhiking off the British Chain Home  radars to conduct air surveillance  during WWII is an example.53,54 A hitchhiker implanted in or flying over hostile areas  could use any high-powered satellite transmitter illuminating that area to conduct  short-range surveillance in the receiver-centered oval. The most significant system to use a dedicated transmitter is the Space Surveillance   (SPASUR ) 217 MHz multistatic radar fence. 
 Many practical integrators, however, have a" loss of memory" with time. That is, the ampli­ tude of a signal stored in such an integrator decays, so that the stored pulses are not su mmc.:d  with equal weight as assumed above. Practical analog integrators such as the recirculating  delay line (also called a feedback integrator), the low-pass filter, and the electronic storage  tube apply what is equivalent to an exponential weig.hting to the integrated pulses; that is, if 11  pulses are integrated, the voltage out of the integrator is  N  V = L Vi exp [ -( i -1 )y] (2.34)  l= l  where Jti is the voltage amplitude of the ith pulse and exp ( -y) is the attenuation per pulse. 
 The clutter can be calculated as in a pulsed radar, then folded in  range as a function of the PRF. Ground Clutter in a Moving Radar.  When the radar is moving with a velocity  VR, the clutter is spread over the frequency domain as illustrated in Figure 4.2 for the  special case of horizontal motion. 
 SHIFTING INNOVATIONS BY THE 3!2 DESIGN TEAM !NTENNA 4HE KEY ELEMENT IN ANY SPACE 
   PP n  .OVEMBER   0 : 0EEBLES  *R  h-ULTIPATH ERROR REDUCTION USING MULTIPLE TARGET METHODS v  )%%% 4RANS    VOL !%3 
 The elliptic filter designed for  these parameters has an improvement factor of 57.2 dB. HBW (hits per one-way 3-dB  beamwidth) are 22.6. The specifications for the elliptic filter for the above parameters  are normalized stopband edge sfT = 0.03492; passband edge sfT = 0.07350; stop-   band attenuation 58 dB below peak filter response; and passband ripple = 2.0 dB. 
 PANEL DISPLAY 4HIS DISPLAY WAS  CREATED IN SUPPORT OF 53 HOMELAND DEFENSE FOR THE &EBRUARY     3UPER "OWL 8, 4HE 3UPER "OWL 8, 2OMAN NUMERAL FOR   IS A CHAMPIONSHIP FOOTBALL GAME  &)'52%  !2%03 HOMELAND DEFENSE APPLICATION . 
 PERFORMANCE RADARS !DDITIVE NOISE SOURCES CAN BE EXTERNAL TO THE RADAR  SUCH AS ATMOSPHERIC NOISE  SKY TEMPERATURE   GROUND NOISE BLACK BODY RADIATION   AND JAMMERS  OR THEY CAN BE INTERNAL  SUCH AS THERMAL NOISE 4HERMAL NOISE IS ALSO KNOWN AS  *OHNSON NOISE AND    '   '    '    '     '   ($#&!) *     % .!$+$ "!%)+)&! # , # * .!$+$!%)+)&! # , # *    
 ,/" - 4HE ACCURATE CONVERSION OF THE RADAR )& SIGNAL INTO A DIGITAL REPRESENTATION OF THE  COMPLEX ENVELOPE IS AN IMPORTANT STEP IN THE IMPLEMENTATION OF  A MODERN DIGITAL SIG 
      . ÓÈ°È  2!$!2 (!.$"//+  TO THE %ARTHS DIMENSIONS  AND LITTLE ENERGY IS DIFFRACTED !T OPTICAL FREQUENCIES OR  VERY SHORT RADAR WAVELENGTHS  THE OPTICAL HORIZON REPRESENTS THE APPROXIMATE BOUNDARY BETWEEN REGIONS OF PROPAGATION AND NO PROPAGATION 4ROPOSPHERIC 3CATTER  !T RANGES FAR BEYOND THE HORIZON  THE PROPAGATION LOSS  IS DOMINATED BY TROPOSCATTER 0ROPAGATION IN THE TROPOSCATTER REGION IS THE RESULT OF SCATTERING BY SMALL INHOMOGENEITIES WITHIN THE ATMOSPHERES REFRACTIVE STRUCTURE !T RADAR FREQUENCIES  TROPOSCATTER IS GENERALLY NOT CONSIDERED FOR RADAR RANGE PERFOR 
 MAf-68-4121-5, Bell Telephone Laboratories, Whippany, N.J., 1968. 41. Hildebrand, P. 
 This usually destroys the operational  value of the target. Most of the rotators for these pylons are dual-axis, azimuth-over- elevation designs. When measurements are made with the azimuth rotation angle tilted  back (away from the radar), parts of the target may sweep through the shadow cast  by the top of the pylon, possibly degrading the measurements. 
 Most of these measurements were in the 10 to 80° range of incidence angles. Measurements near vertical are scarcer, while well-controlled experiments near grazing are very scarce indeed. Airborne measurements are necessary to make larger scattering areas acces- sible. 
 SIDERATION IN RECEIVER FRONT 
 -/" ]Ê ",7, Ê , 
 The diode avoids these diffi- culties, since itcuts offduring theduty interval but closes togive a low impedance during recycling. The” triode cuts offalmost as quickly asthediode and provides aconvenient method ofprovid- ing voltage control since itdraws nocurrent from the variable potential source. When extreme precision isrequired, thedefects duetothecharge drawn from C,and theless-than-unity gain ofthecathode follower may beimportant. 
 SYNCHRONOUS  SATELLITES  HOST  %UROPEAN  3PACE  !GENCY %3!  ALTIMETERS ON %23 
 S INCIDENCE  WHICH CAN LEAD TO CONFUSION  IF THE VALUE OF THIS PARAMETER IS IMPORTANT IN A GIVEN APPLICATION 4HE SAME CAVEAT APPLIES TO 0!,3!2  DESCRIBED IN A SUBSEQUENT PARAGRAPH. 
 Moore: A High Performance CW Receiver Using Feedthru Nulling, hlicro-  wave J., vol. 6, pp. 63-71,'September; 1963. 
 LINE AND MAIN 
 # AMPLIFIER OFFERS HIGHER EFFICIENCY OVER #LASS 
 I      x.J     x. 
 J. Huang, G. Jackson, S. 
 40. A. Luscombe, A. 
 Itisclear that since thefanisperpendicular tothefloor oftheairplane itisnot atthe moment vertical, and that therefore thetargets onthe straight line on the ground now being illuminated bythebeam arenot atzero bearing. Since such targets arenevertheless displayed asifatzero bearing, the display isdistorted; these targets areshifted byanamount equal tothe altitude ofthe airplane multiplied bythe tangent ofthe bank angle. Other targets areless seriously disturbed, those at90° and 270° being correctly indicated onabanking airplane. 
 20.6. A normalized sensitivity factor k = KKlL is plotted versus the w-space ele- vation angle of arrival u = ZA sin 0, with 0 referenced to the boresight of the sum and delta beams. The monopulse sensitivity factor peaks and is symmetrical about the boresight angle. 
 NOISE RATIO 4O DYNAMICALLY MAKE THIS COM 
 Nntc that Itqs. (4.1) to (4.3) rcprescnt siiic-wave carriers upon whicli the pulse modulatiori is  iinposcd. 'I'lle differericc frequency is equal to tlie doppler frequency,fd. 
 CLUTTER VISIBILITY IS POTENTIALLY OBTAINABLE FROM COHERENT #-2S  WHICH HAVE  BEEN MADE AFFORDABLE BY THE CONTINUED REDUCTION IN COST OF MICROWAVE POWER SEMICON 
 RADAR C'LllTTFR 471  radar-cross-section dl'11sity rather ·than the radar cross section as was described for conven­ tional targets in Sec. 2.7. For surface clutll:r a cross section per unit area is defined as  (I  (I = (LU)  where r,c is the radar cross section from the area :lc. 
 ch08.indd   6 12/20/07   12:49:41 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 
 Acam actuates themotion oftheplate, while thelinkage holds the adimension uniform along the variable waveguide. Toone ofthetoggles isattached acam socutastodrive asynchro data take-off through anangle equal to6. The chokes shown inthe channel and inthe plate serve toprevent leakage from the varying guide sothat the loss due both tothe finite conductivity ofthe waveguide and tothe leakage past the long choke iskept down toabout ~db/m during most ofthe scan. 
 SYNCHRONOUS  4HESE ORBITS ARE ALSO AT LOWER ALTITUDES  THAN THE 40 ORBIT  WHICH IMPLIES THAT ORBIT MAINTENANCE MANEUVERS MUST BE MORE FREQUENT  THUS COMPROMISING PRECISION ORBIT DETERMINATION $URING A PORTION OF ITS MISSION  THE ORBIT OF %23 
 Many radar systems operate over a range of  RF frequencies, requiring a number of LO frequencies that are typically generated  using frequency synthesis. Frequency synthesis is the process of creating one or more  frequencies from a single reference frequency using frequency multiplication, divi - sion, addition, and subtraction to synthesize the required frequencies. The fundamental  building block of any frequency synthesis approach is the oscillator. 
 For  example, the presence of virga53 (precipitation aloft but evaporating before reaching  the surface) associated with so many shower-type clouds in dry climates indicates that  convective shower rainfall profiles are much more difficult to model. Attenuation by Hail . Ryde47 concluded that the attenuation caused by hail is  one-hundredth of that caused by rain and that ice-crystal clouds cause no sensible  attenuation and show very small attenuation even at the excessive rate of fall of 5 in/h. 
 The dropletsizesoffreezing rain,however, arelargeandthecollection efficiency canapproach 100 percent. Drysnowdoesnotsticktocoldsurfaces andisgenerally noproblem. Snowmight collectonthetopportionoftheradomebutwillbequicklyremoved byanyfollowing wind. 
   
 The receiver noise-figure can be measured with a broadband noise source of known  intensity, such as a gas-discharge tube22 or a solid-state noise source. The noise figure 1s  determined by measuring (1) the noise power output N, of the receiver when a matched  impedance at temperature To = 290 K is connected to the receiver input and (2) the noise  power output N2 when a matched noise generator of temperature T2 is connected to the  receiver input.2 The temperature T2 is the equivalent noise temperature of the broadband noise  senerator. The noise figure can be shown to be  where Y = N2/Nl. 
 Rebecca-  Eureka, out of which has come many modern naviga-  tional radar aids, was devised by F. C. Williams and  J. 
 It is computed by assuming a uniformly distributed target dop - pler over one filter spacing and is a function of the doppler filter sidelobe weighting. This  loss can be reduced (at the expense of increased processing) by zero-padding the collected  data and performing a higher-point FFT to form highly overlapped doppler filters.FIGURE 4.21  Comparison of detection performance with and without eclipsing and range gate  straddle loss. The approximate performance using Eq. 
  FROM ' 6 4RUNK AND 0 + (UGHES . 
 vol. 54.  pp. 
 Iiowever. is not as pronounced in the case of the round earth: the minima are  not as deep nor are the maxima as great since a wave reflected from a curved surface is more  divergent than one reflected from a plane. The other region of interest is that which lies just  beyond the interference region below the radar line of sight and is the diffraction. 
 6  LIFECYCLE OF RADAR M EASUREMENT TASKS  ..............................  7  CHALLENGES OF RADAR DESIGN & VERIFICATION  ...............................  7  CHALLENGES OF PRODUCTION TESTING ................................ 
 For certain actual microwave radars and beacons, something like five radars giving steady interrogations are allowable without serious impairment ofthepresentation. Where necessary, this number can beincreased by designing the beacon tohave ashorter dead time. Sofarinthis discussion, the results ofscanning bytheinterrogating radars have been ignored. 
 cc ¯PFT  #ONVOLUTION OF SIGNALS XT  AND YT   YT XT HT XH T D X T H            
  
 RATE NEGATIVE FOR  AN INCOMING TARGET    C IS THE SPEED OF LIGHT  AND  K   CF  M  IS THE CARRIER WAVELENGTH -ATCHED &ILTERS  ! MATCHED FILTER ACHIEVES MAXIMUM OUTPUT SIGNAL 
 From Figure 4, we can know that a higher predictor factor corresponding to a higher predicted energy ratio, which can be explained that more predicted signal contribute more energy. Higher energy radio means a higher uncertainty. Typically, predictor factors less than 3 always lead to useful results 76. 
 Lett. 2013 ,10, 1552–1556. [ CrossRef ] 19. 
 SIMPLIFIEDVIEW OF BISTATIC RANGE COVERAGE AND MUST BE USED WITH CARE !N ADDITIONAL BISTATIC CAVEAT IS NECESSARY 7HEN THE TARGET IS  ON OR NEAR THE BASE 
 REFLECTIVITY AGRICULTURAL PATTERNS AND DESERT LAND 4HE REFER 
 Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar.  AN INTRODUCTION AND OVERVIEW OF RADAR  1.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 detection rather than receiver noise. It can happen that the detection capability of a radar  might be limited by clutter in some regions of its coverage and be limited by receiver  noise in other regions. 
 Although the wavelength of Ka band is about 8.5 millimeters (a frequency of 35 GHz), the technology of Ka- band radar is more like that of microwaves than that of millimeter waves and is seldom considered to be representative of the millimeter-wave region. Milli- meter-wave radar, therefore, is taken to be the frequency region from 40 to 300 GHz. The exceptionally high attenuation caused by the atmospheric oxygen absorption line at 60 GHz precludes serious applications in the vicinity of this frequency within the atmosphere. 
 elements is summed in space. An array whose elements are distributed  on a nonplanar surface is called a conformal array.  An array in which the relative phase shift between elements is controlled by electronic  devices is called an electronically scanned array. 
 It becomes  clear, that a low noise figure receiver is accomplished by a good design in the very front -end  components. An aspect to a very low noise figure receiver is achieved through minimizing the noise  factor of the very first block. This component usual is characteri zed by a low noise figure with high  gain. 
   6n n   
 G. Mace, K. Sassen, Z. 
 Ward, Handbook of Radar Measurement , Englewood Cliffs, NJ:   Prentice-Hall, 1969, pp. 242–338. 66. 
 MENT IN MANY IMPORTANT APPLICATIONS 4HREE SUCH 0% MODELS ARE T HE 4ERRAIN 0ARABOLIC  %QUATION -ODEL 40%-    THE 4ROPOSPHERIC %LECTROMAGNETIC 0ARABOLIC %QUATION  2OUTINE 4%-0%2   AND THE 6ARIABLE 4ERRAIN 2ADIO 0ARABOLIC %QUATION 6420%  (YBRID -ODELS  7HILE 0% MODELS ARE VERY ATTRACTIVE  THEY ALSO HAVE THEIR DISAD 
 In the configurations shown, the zeros are con - strained to the unit circle. To move the zeros off of the unit circle, which may be done  to control the flatness of the filter passband response, requires a configuration similar  to the elliptic filter configuration shown in Figure 2.46 later in this chapter. The triple- canceler configuration shown is such that two of the zeros can be moved around the  unit circle in the Z plane. 
 821–829, November 1974. ch09.indd   49 12/15/07   6:08:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Detection ranges of Chivenor buoy and Lundy Island, aircraft height 1000 ft (**: ‘moderate ’sea; *: ‘slight to moderate ’sea). RadarAverage detection range, Chivenor buoy, nmiAverage detection range, Lundy Island, nmi ASV Mk. III ** 20 31.5 ASV Mk. 
 Time and radar power (or energy) are two resources that must be properly handled in a . ]26 INTROIHJC'TION TO RADAR SYSTl:MS  Communicalions  Phase shifter  orders Command  data  buffer  I:. full Data  routed" : ", . 
 l lists  Table 10.l Efficiency of nonmatched filters compared with the matched filter  Loss in SNR compared  Input signal Filter Optimum Br with matched filter, dB  Rectangular pulse Rectangular l.37 0.85  Rectangular pulse Gaussian 0.72 0.49  Gaussian pulse Rectangular 0.72 0.49  Gaussian pulse Gaussian 0.44 0 (matched)  Rectangular pulse One-stage,  single-tuned circuit 0.4 0.88  Rectangular pulse 2 cascaded single-tuned  stages ... :· . , ~ . 
 :::~:::: 626 16.3 APractical MTI System. .. 632 16.4 Alternative Methods forObtaining Coherence. 
 The rectilinear coordinates of the updated target prediction are converted back to  radar coordinates to drive the antenna.  Systematic errors are determined by prior measurement atld arc used to arijust the  encoded antenna position to provide the correct target position. Systematic errors include  (1) error in the zero reference of the encoders that indicate the orientation of the radar axes,  (2) misalignment of the elevation axis with respect to the azimuth axis (nonorthogonality),  (3) droop or flexing of the antenna and mount caused by gravity, (4) misalignment of the radar  with respect to the elevation axis (skew), (5) noncoincidence of the azimuth plant: of tht: mount  to the local reference plane (mislevel), (6) dynamic lag in the servo system, (7) finite transit  time that resillts in the target being at a different position by the time the echo is received by  the radar, and (8) bending and additional time delay of the propagation path due to atmo-  spheric refraction. 
 For the general bistatic case, where L > 0, the  free-space maximum detection contour becomes the familiar oval of Cassini, again   *  In the first case, the transmitter illuminates the target over the receiver’s shoulder; in the second case, the receiver  views the target over the transmitter’s shoulder. ch23.indd   6 12/20/07   2:21:09 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 152 HOW RADAR WORKS  device) or ‘mouse’ transmitter, measures the ground  speed of the aircraft as it approaches its home run along  the track, and sends a signal to the navigator when he is  immediately over it, if the need is to drop bombs, or  when he is suitably approaching for a landing. On some  wartime aircraft it was arranged that this Station B  ‘mouse’ signal itself released the bombs, and, of course,  there are several obvious peacetime applications of such  a radar-controlled relay. To try the system as quickly as  possible during the war years Oboe Mark I was pro-  duced using carrier frequencies in the 14-metre band. 
 Then, the original weights are perturbed to produce nulls in the desired direc - tions of the antenna pattern. The intent of the perturbation algorithm is to maximize  the signal-to-interference-plus-noise ratio, while minimizing the deviation between  the original element weights and the perturbed element weights.104 Full amplitude and  phase control at each element ensures that the perturbed antenna pattern has nulls in the  desired directions with minimally perturbed weights.102 However, phase-only control  FIGURE 13.39  Array configurations for perform - ing deterministic RF nulling: ( a) amplitude and phase  control at each element and ( b) phase-only control at  each element ch13.indd   58 12/17/07   2:41:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Rush: Microwave Doppler Sensors, Microware J.. vol. 17, pp. 
 A parabola reflects a spherical wave into a plane wave only when the source is at the focus. With the source off the focus, a phase distortion results that in- FIG. 6.14 ASR-9 shaped reflector with offset feed and an air traffic control radar beacon system (ATCRBS) array mounted on top. 
 FEROMETRIC BASELINE IS REQUIRED  WHICH IMPLIES TWO OR MORE  3"2S IN RELATIVELY TIGHT CO 
 TO 
 S TO CONFIRM THE EXISTENCE OF "RAGG SCATTER AT CENTIMETER WAVELENGTHS   WHILE AT THE OTHER END OF THE  EXPERIMENTAL SCALE  THE CHAOS OF A FULL 
 and  exreriments verify, that the cross section per unit area <r0 corresponding to the larger resonant  component is -29 dB, independent or sea state and frequency. 25·26 This allows that compo­ nent to be used as a calibration standard.  Thus an examination or the doppler spectrum of the sea can give the sea roughness and  direction, from which can he inrerred something about the winds driving the sea. 
 But we are  now at this point not so much concerned with time as  with distance, and if we adjust the Cal to produce a  spike of light on the time-base every ssizsecond this will  correspond to a distance of 10 miles on our electron  ‘ruler.’ So we call Cal pips thus set up our ‘1o-mile  paps,’ or, if we run the Cal circuits twice as fast, there  will be twice as many spikes of light, and they, of course,  will mark 5-mile intervals. On some very precise radar apparatus we even check by using 1-mile Cal pips. The  caliprater is just a check. 
 Theproblem incombining theoutputsofNportsintooneport,orviceversa,istodosowithminimum loss. Itisnotalwaysappreciated thatlossinthearrayfeedisequivalent toalossinantenna power gam. Thereareatleastthreebasic'concepts forfeedinganarray.Theconsrrainedfeed utilizes waveguide orothermicrowave transmission linesalongwithcouplers, junctions, orother powerdistribution devices. 
 Therefore, it may be expected that when a grating lobe is about to emerge into real space, the coupled voltages tend to add in phase and cause a large mismatch. If the dielectric protrudes from the aperture or if a dielectric sheet covers the aperture (this is one technique for scan compensation discussed below), a large reflection may occur well before the grat- ing lobe reaches real space.70 If a surface-wave velocity of vs is assumed, the couplings will add in phase when £ = 1 X clvs + sin B0 For the purposes of mutual coupling, a slow wave across the aperture may be envisioned as being equivalent to spacing the elements farther apart in free space. A phenomenon that produces similar effects can come about without dielectric in front of the aperture, e.g., by using a periodic structure of baffles. 
 The transmitter and receiver were separated by about 5.5 miles. When the aircraft receded  from the receiver, it was possible to detect the beats to about an 8-mile range.  By June, 1935, the British had demonstrated the pulse technique to measure range of an  aircraft target. 
 Over the years, many propagation  models have been developed to account for the effects important to a particular appli - cation. These models span the spectrum of very fast executing but with low fidelity  (simplified modeling of or the complete ignoring of certain propagation mechanisms)  to relatively slow executing but with high fidelity (physically rigorous modeling of  and full inclusion of all propagation mechanisms). Spherical Spreading or Free-space Propagation Model. 
 BIT INPUT DATA B$!4!     AND A  
 DATE THIS CHANGE /THERWISE  USE OF A FIXED BEAMWIDTH INCURS A SMALL BEAM MISMATCH LOSS !N EXAMPLE IS GIVEN IN 7ILLIS  %VEN THOUGH ONE PULSE MUST BE CHASED AT A TIME  A HITCHHIKER OPERATING IN THE  CO 
 Barton12 © IEEE 1967 ) FIGURE 2.17  PPI display, 30-nmi range of ( a) all clutter at a mountainous site and ( b) clutter that exceeds  the system noise level by 60 dB ch02.indd   18 12/20/07   1:43:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 10.31  Taylor Weighting with  Linear FM  ........................  10.31  Discrete Time Weighting  ....................................  10.34 Amplitude and Phase Distortion  ......................... 
 5.6 with the addition ofamodulator for the transmitter, another audio channel, and aphase meter. No detailed description will begiven because, asyet, nogreat practical application ofthe method has been made. The principal difficulty atpresent isthelack ofawell-developed phase meter that will work over arange ofboth frequent yand amplitude. 
 TRACKING SERVO LOOP AND PLACE THE ANTENNA BEAM AT ABOUT A HALF BEAMWIDTH ABOVE THE HORIZON  !ZIMUTH CLOSED 
 Othererrorsmightbeintroduced intheCWradarifthereareuncontrolled variations in thetransmitter frequency, modulation frequency, orfrequency excursion. Targetmotioncan causeanerrorinrangeequaltoVrTo,where VristherelativevelocityandToistheobservation time.Atshortrangestheresidual patherrorcanalsoresultinasignificant errorunless compensated for.Theresidual patherroristheerrorcausedbydelaysinthecircuitry and transmission lines.Multipath signalsalsoproduce error.Figure3.14showssomeofthe unwanted signalsthatmightoccurintheFMaltimeter.36.37Thewantedsignalisshownby thesolidline,whiletheunwanted signalsareshownbythebrokenarrows.Theunwanted signalsinclude: 1.Thereflection ofthetransmitted signalsattheantennacausedbyimpedance mismatch. 2.Thestanding-wave patternonthecablefeedingthereference signaltothereceiver, dueto poormixermatch. 
 Figure 10.1 depicts the principal parts of a three-cavity klystron. At the left is the  heater that heats the cathode and the cathode  that emits a stream of electrons that are  collimated into a narrow cylindrical beam of high electron density. The electron gun   that generates the beam consists of the cathode,  the modulating anode  (also called  the beam control grid ), and the anode . 
 89. Gupta, D. V., J. 
 1 Liquid delay lines were large and inconvenient to use. They were replaced in the  mid-l 950s by the solid fused-quartz delay line that used multiple internal reflections to obtain  a compact device. These analog acoustic delay lines were, in turn supplanted in the early 1970s  by storage devices based on digital computer technology. 
 Theechosignalreceived attheradaris sin[2rrfo(t-T)].Ifthetransmitted andreceived signalsarecompared inaphasedetector, theoutputisproportional tothephasedifference between thetwoandis114>=2rrfoT= 4rr!~Ric.Thephasedifference maytherefore beusedasameasure oftherange,or R=~114>=~114> 4~fo4rr However, themeasurement ofthephasedifference 114>isunambiguous onlyif114>doesnot exceed2nradians. Substituting 114>=2nintoEq.(3.17)givesthemaximum unambiguous rangeas),/2.Atradarfrequencies thisunambiguous rangeismuchtoosmalltobeofpractical interest. Theregionofunambiguous rangemaybeextended considerably byutilizing twoseparate CWsignalsdiffering slightlyinfrequency. 
 J.: Remote Sensing with the Jindalee Skywave Radar, IEEE J. Ocean. Eng., vol. 
 Two of the more  Figure 3.1 Doppler frequency [Eq. (32h)) as a function of radar frequency and target telalive velocity.  CWANDFREQUENCY-MODULATED RADAR69 IIIq,wilhrespccttolilllcisequal10afrequency. 
 AES.  135. Punnett. 
 17 to 17.18 N NCAR dual band radar, 19.17 Networked radar, 7.46 to 7.49.     I_10 Nexrad (WSR-88D) weather radar, 19.1, 19.16 to 19.17 automated weather products, 19.25 Noise, in receiver, 6.4 to 6.5 Noise, in tracking, 9.27 to 9.30 Noncooperative air target recognition, 5.22 to 5.24 Nonlinear FM pulse compression, 8.12 to 8.16 Nonparametric detectors, 7.17 to 7.18 Nonspecular absorbers, 14.38 nth-time-around tracking, 9.24 Nyquist, 25.2, 25.4 to 25.6 O Ogive, radar cross section of, 14.7 to 14.8 On-axis tracking 9.25 to 9.26 Operating bandwidth, 6.9 Optics region, 14.5 to 14.6 Optimal detection, 7.2 to 7.4 Orographic rain, 19.26 Oscillator vs. amplifier transmitter, 10.4 Ovals of Cassini, 23.6 to 23.8 Over-the-horizon radar antennas for, 20.24 to 20.26, 20.45 to 20.46 calibration, 20.48 to 20.49 clutter, 20.29 to 20.33 coherent processi ng for, 20.6 compared to microwave radar, 20.7 to 20.10 doppler spectrum of the sea, 20.49 to 20.52 and ECCM, 24.52 to 24.53 examples of, 20.11 to 20.12 external noise in, 20.40 and meteor trails, 20.38 to 20.40 noise models, 20.43 to 20.45 oceanography, 20.33 to 20.38 performance modeling, 20.55 to 20.70 propagation factor, 20.6 to 20.7 radar cross section, 20.26 to 20.29 radar equation, 20.5 to 20.7 receiving system, 20. 
 As before, it is assumed that the signal is large compared  with noise; consequently there is no doubt as to the existence or the approximate position of  the echo pulse.  Mult~pl~er  Figure 11.2 Receiver for rneas~lring range (time delay)  using a gating signal g(t - TH), where TR is the estimate  of the true time delay. Note the similarity to the cross-  q (t-7;7) correlation receiver of Fig. 
 &ROM THE USERS POINT OF VIEW  THE MOST VISIBLE AND IMPORTANT CHANGE IN MARINE RADAR FROM ITS EARLY DAYS HAS BEEN THE DEVELOPMENT OF PROCESSOR 
 At (J O (beam hroadskle lo Ilic army) a symmclrkal pencil beam of  half-power width B0 is assumed. The shape of the beam at the other angular positions is the  projection of the circular beam shape 011 the surface of the unit sphere. It can be seen that as  the hcam is scanned in the O direction, it broadens in that direction, but is constant in the¢,  direction. 
 2.13.  Shaping of the target, as with the cone-sphere, is a good method for reducing the radar  cross section. Materials such as carbon-fiber composites, which are sometimes used in aero­ space applications, can further reduce the radar cross section of targets as compared with that  produced by highly reflecting metallic materials.62  bl':'<  0  r::  Q  u  (I)  "' "' Ill  ~ u  ~  0  0  0  0:: +10  0  10  Cone Sphere  -20 ,  \ I  I 1-. 
 705-716, June, 1974.  158. Ethington, D. 
 SURFACE RESPONSE FUNCTION WAVEFORM ARE SOFTENED BY THE PULSE WEIGHTING  AND THE  WAVEFORM IS ATTENU 
 Figure 19. Interferometric phase image of phase wrapping. The measured interferometric phase value shown in Figure 19was modulated by 2 π, ranging from −πtoπ, and there was an ambiguity of many cycles in the interferometric phase value. 
 PHASE TAPERS DEFINED BY THE BEAM 
 Cusson, D.; Trischuk, K.; H ébert, D.; Hewus, G.; Gara, M.; Ghuman, P . Satellite-based InSAR monitoring of highway bridges—Validation case study on the north-channel bridge in Ontario, Canada. T ransp. 
 (The pulsi.:  radar has no similar limitation to its maximum range because the transmitter is not operative  when the receiver is turned on.)  Perhaps one of the greatest shortcomings of the simple CW radar is its inability to obtain  a measurement of range. This limitation can be overcome by modulating the CW carrier, as in  the frequency-modulated radar described in the next section.  Some anti-air-warfare guided missile systems employ semiactive homing guidance in  which a receiver in the missile receives energy from the target, the energy having been trans­ mitted from an" illuminator" external to the missile. 
 Its 1-dB bandwidth is 39 MHz, but it is inherently capable of greater values. A peak  204INTRODUCTION TORADAR SYSTEMS problem, butthetunerincreases thecavitycapacitance andthusdecreases thecavityim­ pedance sothatthereisreduced bandwidth atthelow-frequency endofthetuningrange. Tuningrangesof10to15percentcanbeobtained without acompromise inimpedance by usingasliding-contact movable cavitywall,butattheexpense ofincreased mechanical complexity. 
 The EMAM method not only avoids the azimuth sidelobe lifting, but also gets rid of the azimuth sidelobe asymmetry. Speciﬁcally, the EMAM method ﬁrstly achieves sub-view images via multi-looking processing. Then, a sliding-window-based cross-correlation is implemented to achieve image offsets. 
 The radiation pattern from a torus with a well-designed organ-pipe scanner changes but  little until the beam reaches one end of the scanning aperture. At this point the energy appears  at both ends of the aperture and two beams are found in the secondary pattern. The antenna  /f Equal lengths of  ( \ ~,oveguide  ~------ Figure 7.17 Principle or the organ-pipe  scanner. 
 If the phases of consecutive received  pulses relative to the phase of the coho differ by, say, 0.01 rad, a limitation of 40 dB  is imposed on I. The 0.01-rad clutter vector change would be equivalent to a target  vector, 40 dB weaker than the clutter, being superimposed on the clutter, as shown  in Figure 2.72. In the power amplifier MTI system shown in Figure 2.73, pulse-to-pulse phase  changes in the transmitted pulse can be introduced by the pulsed amplifier. 
 The functional block diagram and operation of a specific sensor mode is then over - laid on this hardware and software infrastructure. A specific mode is implemented in an  applications program in the same sense that word-processing is on a personal computer  (PC). Carrying the analogy further, common experience with the unreliability of PC  hardware and software requires that a system of the type depicted in Figure 5.3 must  be redundant, error checking, trusted, fail safe in the presence of faults, and embody  strict program execution security. 
 Sensors 2019 ,19, 1920 where Ta=NaTr, is deﬁned as the CPI in one look direction, and Tris the pulse repetition interval (PRI). Nais the coherent pulse number in one CPI. Assuming that there are Kscattering centers in one range cell, and fast Fourier transform (FFT) is performed to get the DBS imaging result [ 1,8,9]: S(τ,f)=sin c⎭bracketleftbigg B⎭parenleftbigg τ−2R0 c⎭parenrightbigg⎭bracketrightbigg sinc[Ta(f−fk)] (9) From Equation (9), it can be seen that the Doppler resolution in the conventional FFT-based method is approximately determined by: δfd=1/Ta (10) whereδfdis the Doppler resolution. 
 Bandwidth and Matching Factors. The frequency-response width (band- width) of the receiver selective circuits appears explicitly in Eqs. (2.4) to (2.6), but it is an implicit factor in the other range equations as well, through the factor CB. 
 CENTRIC  USING EVERYTHING AVAILABLE ON 
 MADE NOISE  BUT IDEALLY THE CURVE WOULD BE BASED ON MEASUREMENTS AT THE PARTICULAR RADAR SITE 4HE  GALACTIC 
 SEC.16.2] BASIC PRINCIPLES OF MTI 631 This canbedone byallowing asufficient amount ofpower from thetrans- mitter toenter theresonant cavity oftheoscillator, which isthen forced into step with the transmitter. This process iscalled “locking” the phase ofthe oscillator, ormaking it“coherent.” The appearance of theA-scope will bethesame asthat shown inFig. 16”5. 
 144 C-W RADAR SYSTE.JfS [SEC. 58 give rise toabeat’ j~,asshown inthebottom graph ofFig. 5.12. 
 If the feed maintains the plane of polarization fixed as it rotates,  it is called a 1111rati11g feed. A rotating feed causes the polarization to rotate. The latter type of  feed requires a rotary joint. 
 All the various methods of scanning are then possible, including the beam-switching system described be- low, and can be carried out at IF, where amplification is readily available and lumped constant circuits may be used. Digital Beamforming.32~34 For receiving, the output from each radiating el- ement may be amplified and digitized. The signal is then transferred to a com- puter for processing, which can include the formation of multiple simultaneous beams (formed with appropriate aperture illumination weighting) and adaptively derived nulls in the beam patterns to avoid spatial interference or jamming. 
 (13.33)  /\!though the output fluctuations about the mean arc constant, the output mean is not. A  high-pass filter removes the mean value of the output, leaving the fluctuation of the clutter at a  constant level on the display. The high-pass filter is equivalent to a differentiation, or to  a circuit with a fast time-constant (FTC). 
 G. Kouyoumjian and L. Peters, Jr., “Range requirements in radar cross section measurements,”  Proc. 
 '(Z INTERNAL CLOCK SPEED $!# UPDATE RATE  $IGITAL  0ULSE  #OMPRESSIONn $IGITAL PULSE COMPRESSION TECHNIQUES ARE  ROUTINELY USED FOR MATCHED FILTERING OF RADAR WAVEFORMS 4HE MATCHED FILTER MAY BE  IMPLEMENTED BY USING A DIGITAL CONVOLUTION FOR ANY WAVEFORM OR ELSE BY USE OF STRETCH  PROCESSING FOR A LINEAR 
 Values asafunction ofwavelength and forvarious speeds are given inthecurves ofFig. 5.9. The modulation frequency is ordinarily made aslarge aspos-the beat f,between the two leakage band and unless special measures are 10,OCO m~ \ \ mmI Iw \ 4m\ \ 2Q30 E“~10W \.Soo m 2C0 12 46S1O 20 40643s0100 Xincm FIG.5.9.—Doppler frequency asafunction of wavelength, forvarious radial velocities. 
 53 . Superresolution. The resolution of a conventional antenna is limited by the well-known Rayleigh criterion, which states that two equal-amplitude noise sources can be resolved if they are separated in angle by 0.8 X/L, in radians, where X is the wavelength and L is the aperture length. 
 LOOKING CONFIGURATION PRODUCES A STRIP IMAGE  THE OUTPUT FILMS ARE USUALLY IN THE FORM OF LONG STRIPS -OST CAMERAS PRODUCE SEPARATE IMAGES THAT ARE APPROXIMATELY SQUARE 3TRIP FILM CAMERAS AND OPTICAL 
 M., M. U. Palma, and D. 
 It sets a thresh - old level for individual radars such that it only responds to high-power main beam  interrogations. Typically, peak transmit powers are about 1–2 watts. Antennas are usu - ally omnidirectional in azimuth but can have a restricted elevation beamwidth and  typically have an overall gain of about 6 dB. 
 TABLE 10.2 Characteristics of Passive Linear-FM Devices pulse compression. These passive devices fall into two broad classes: (1) bulk ultrasonic devices in which an electrical signal is converted into a sonic wave and propagates through the medium and (2) electrical devices that use the dispersive characteristic of an electrical network. The main objectives in designing and selecting a device are (1) a flat-amplitude characteristic over the bandwidth B, (2) a linear delay slope with a differential delay T across the bandwidth B, (3) minimum spurious responses and minimum distortion to achieve low sidelobes, and (4) a low insertion loss. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 FIGURE 2.28  Optimum improvement factor for polynomial clutter spectrum model FIGURE  2.29 Optimum improvement factor for Billingsley’s exponential spectrum model ch02.indd   32 12/20/07   1:44:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 INSTITUTION OF ELECTRICAL ENGINEERS: Proceedings at  the Radiolocation Convention (1946).  MacGrecor-Mornris, J. T., and Mies, R.: “‘ Measure-  ments in Electrical Engineering by Means of  Cathode Rays,” in Fournal of the Institution of Elec-  trical Engineers, 1925. 
 Marcum considered only steady signals (target cross section not varying dur- ing the period of observation), and most of his results assume the use of a square- law detector. Robertson4 has published exceptionally detailed and useful steady- signal results applicable to the linear-rectifier detector, which is the type of detector almost universally used. (The square-law-detector results are also useful because they differ very little from the linear-detector results.) Swerling extended Marcum's work to include the case of fluctuating signals.5 His report was repub- lished in IRE Transactions on Information Theory in 1960. 
 From the radar engineering stand - point, the challenge is considerable, requiring radar designers to develop coherent  waveform, polarization-diverse, and wavelength-diverse radars. As noted, there exist  several polarimetric research radars and operational radars in the world.26 Multiple Radars.  A single doppler radar measures only a single radial compo - nent of velocity. 
 ETRATE THE GROUND AND ARE SCATTERED THEREIN ARE TOO LITTLE KNOWN TO PERMIT ITS EVALUATION £È°{Ê   Ê"Ê,"1  Ê 
 The price paid for this bandwidth expansion is a much thicker, bulkier  material that tends to be impractical for tactical military targets. Like the Salisbury screen, the Dällenbach layer  is also a simple absorber. The mate - rial is uniform throughout its volume and is a mixture of compounds designed to have  a specified index of refraction. 
 Monitoring surface deformation over permafrost with an improved SBAS-InSAR algorithm: With emphasis on climatic factors modeling. Remote Sens. Environ. 
 NAL BANDWIDTH DOES NOT STRADDLE THE .YQUIST FRE 
 LEVEL INTER 
 71. R. J. 
 ENT PROCESSING INTERVAL #0)  CAN BE TREATED AS A SINGLE NONCOHERENT PULSE "ECAUSE THREE AMBIGUOUS MEASUREMENTS IE  DETECTIONS  ARE USUALLY REQUIRED TO REMOVE THE RANGE AND DOPPLER AMBIGUITIES     TO  #0)S MAY BE TRANSMITTED  AND HENCE  THERE  ARE USUALLY  TO  NONCOHERENT PULSES AVAILABLE FOR PROCESSING Ç°ÎÊ 1/" / Ê/,    ! TRACK REPRESENTS THE BELIEF THAT A PHYSICAL OBJECT OR hTARGETv IS PRESENT AND HAS ACTU 
 169  . 170 HOW RADAR WORKS  Plate Hl (p. 113). 
 21,  pp. 39-44, February, 1978.  47. 
 S.: Estimation of Spectral Moments for Weather Echoes, IEEE Trans., vol. GE-17, pp. 113-128, 1979. 
 rIKIKRS    WHERE R IS THE POSITION VECTOR OF INTEGRATION PATCH  D3 AND S IS A UNIT VECTOR POINTING  FROM AN ORIGIN IN OR NEAR THE OBJECT TO THE FAR 
 TION IN THE DOPPLER DOMAIN THAT ALLOWS RESOLUTION IN THE CROSS 
 Only the averaging frequency  counter need be used in an altimeter application, since the rate of change of altitude is usually  small.  A target at short range will generally result in a strong signal at low frequency, while one  at long range will result in a weak signal at high frequency. Therefore the frequency character­ istic of the low-frequency amplifier in the FM-CW radar may be shaped to provide attenua­ tion at the low frequencies corresponding to short ranges and large echo signals. 
 A side lobe level less than - 65 dB is realized and could be improved by an increased length FIR filter impl ementation. The  3-dB width of the compressed pulse is 0.941 µs and the int egrated side lobe level outside +4  dB is- 50.3 dB. The mismatch loss is 0.063  dB. 
 Oceanic Technol ., vol. 11, pp. 727–737, 1994. 
 TO 
 FREQUENCY SPECTRAL COMPONENTS  EACH OF BANDWIDTH  "  THAT ARE COMPLEX 
 Equation 23.20 shows that ( ∆qR)m changes as the receive beam scans out the transmit  beam. Phased array antennas operating with a digital beamformer59,60 can accommo - date this change. Otherwise, use of a fixed beamwidth incurs a small beam mismatch  loss. 
 Klemm, “New airborne MTI techniques,” in International Radar Conference London , 1987,   p. 380. 94. 
 ThisisunliketheNeyman-Pearson Observer inwhichPeawasfixed.Thefunction of theIdealObserver istominimize thetotalprobability oferror.Itaccomplishes thisby adjusting thethreshold, whichinturnaffectsboththefalsealarmandthemissprobabilities. Thedependence ofthetwoerrorsupononeanother isprobably thechieflimitation ofthe IdealObserver asaradardetection criterion. Middleton25statesthatwhentheprobability of falsealarmis0.05,theprobability ofdetection is0.90.Afalse-alarm probability of0.05is usuallyhighformostradarapplications. 
 Thereader,however, willfindonlyafewpagesof theoriginal editionthathavenotbeenmodified insomemanner. Oneofthefeatures ofthefirsteditionwhichhasbeencontinued istheinclusion of extensive references attheendofeachchapter. Theseareprovided toacknowledge thesources ofmaterial usedinthepreparation ofthebook,aswellastopermittheinterested readerto learnmoreaboutsomeparticular subject.Somereferences thatappeared inthefirstedition havebeenomitted sincetheyhavebeenreplaced bymorecurrent references orappearin publications thatareincreasingly difficult tofind.Thereferences included inthefirstedition represented alargefractionofthoseavailable atthetime.Itwouldhavebeendifficulttoaddto themextensively ortoincludemanyadditional topics.Thisisnotsowiththesecondedition. 
 3 19-329, June, 1957.  49. Skolnik M. 
 Trizna: Tests of Remote Skywave Measurment of Ocean Surface Conditions, Proc. IEEE, vol. 62, pp. 
 2.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 This definition assumes that clutter is distributed homogeneously across many  range cells. In this case, the above definition is equally valid before and after pulse  compression. Against point clutter this definition only applies after pulse compression  and may result in a different value of the improvement factor. 
 10.lOa) whose delay is equal to the pulse repetition period. The recirculating- Topped delay line  Vide~  . : : t -~ 0f ~t t t f Integrated .. 
  
 PROCESSING  AND  %3- CAPABILITIES 3ELF 
 &IX WAS PUT THERE  MANY YEARS AGO TO INDICATE IT WAS A hFIXv FOR A PROBLEM THAT OCCURRED AT THE TIME AND WAS TO BE REPLACED BY SOMETHING BETTER )T WAS USUALLY INSTALLED WITH A SWITCH TO TURN IT OFF  IF NECESSARY 4ODAY $ICKE 
 ('ofieri, A,, and A. Smolski: 'l'lie EfTect of Rain on Satellite Co~nmunications Earth Terniinal Rigid  Rntforncs. hlic.ro\c~irrtc. 
 Hagfors (eds.), New York: McGraw-Hill Book Company, 1968, pp. 1–78. 59. 
 . Radar System Engineeri ng Chapter 8 – Pulse Radar  58     8.7 Impulse Integration for Increasing the Sens itivity   With all Radar devices, which are not agile from pulse to pulse, several pulses are reflected  from a target with each sample instance.  One identifies the summation of all pulses from a target as integration. 
 DELAY CANCELER WEIGHTS SHOULD BE  ! #44 4 "# $.. . 
 BAND RETURNS FROM GENTLE BREAKING WAVES IN A WAVE TANK AND FOUND THAT SPECULAR AND CURVATURE SCATTERING APPEARED TO DOMINATE OVER "RAGG SCATTERING FOR SUCH SUR 
 GENERATED  GRAVITY WAVES v * &LUID -ECH  VOL   PP n  *ULY   7 * 0IERSON  *R AND - ! $ONELAN  h2ADAR SCATTERING AND EQUILIBRIUM RANGES IN WIND 
 The targets can be composed of conducting and dielectric materials. At small bistatic angles, the cos ( b /2) frequency reduction term has little effect in  Kell’s pseudo-monostatic region. For example, a 10 ° bistatic angle corresponds to a  0.4% shift in wavelength and usually can be ignored. 
 The fundamental rule is that the image space (illuminated by the antenna) must be  “underspread” if ambiguities are to be avoided.34 The underspread condition is that  T BRDop<1 (18.7) †  Alternatively known as SpotSAR. ch18.indd   22 12/19/07   5:14:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 £È°În  2!$!2 (!.$"//+  &)'52%     !NGULAR DEPENDENCE OF THE DEPOLARIZATION RATIO OF A  SMOOTH SURFACE AFTER & 4 5LABY  2 + -OORE  AND ! + &UNG  &)'52%     -EASURED SCATTERING COEFFICIENT  R  LEFT SCALE  AS A FUNCTION  OF SOIL MOISTURE CONTENT FOR THREE SURFACE ROUGHNESSES 4HE SOLID CURVE IS THE  REFLECTIVITY  ' RIGHT SCALE  CALCULATED ON THE BASIS OF DIELECTRIC MEASUREMENTS  AFTER 4 ,E4OAN Ú )%%%   .   '2/5.$ %#(/  £È°Î &)'52%     #ONTRIBUTIONS TO BACKSCATTER FROM A VEGETATION CANOPY  OVER A SOIL SURFACE   DIRECT BACKSCATTERING FROM PLANTS    DIRECT BACKSCAT 
 PERATURE INVERSION  ANDOR THE WATER VAPOR CONTENT DECREASES RAPIDLY WITH HEIGHT  THE  REFRACTIVITY GRADIENT WILL DECREASE FROM THE STANDARD 4HE PROPAGATING WAVE WILL BE BENT DOWNWARD FROM A STRAIGHT LINE MORE THAN NORMAL !S THE REFRACTIVITY GRADIENT CONTINUES TO DECREASE  THE RADIUS OF CURVATURE FOR THE WAVE PATH WILL APPROACH THE RADIUS OF CUR 
 L. Weber, A. S. 
 Further development wasput asideafterthedemonstration ofthemoreversatile monostatic-radar principle. Bistaticradar laydormant foraboutfifteenyearsuntilitwas"reinvented" intheearly1950sandreceived newinterest.6o Separating thetransmitter andreceiverinthebistaticradarresultsinconsiderably differ­ entradarcharacteristics thanthoseobtained withthemonostatic radar.Thephysical configuration ofabistaticradarisclosertothatofapoint-to-point microwave communica­ tionssystemthantotheusualscanning monostatic radar.Infact,histatic-radar detection of aircraftwithpoint-to-point communications systems hasoftenbeenreported intheliterature. Perhaps themostcommon manifestation oftheprinciple ofthehistaticradaristherhythmic flickering observed inaTVpicturewhenanaircraftpassesoverhead, especially ifthetelevision receiver istunedtoaweakchannel. 
 This CFAR is provided in  older MTI system by IF limiting and, in the MTD implementation, through the use of  high-resolution clutter maps. A quantitative definition of interclutter visibility has not  yet been formulated. Filter Mismatch Loss  The IEEE definition is filter mismatch loss:  The loss in output signal-to-noise ratio of a filter relative to the signal- to-noise ratio from a matched filter. 
 Trunk34 © IEEE 1978 ) FIGURE 7.23  Probability of resolution as a function of range separation: probability of false alarm   is 0.01; sampling rate ∆R = 1.5 samples per pulse width; target strengths, nonfluctuating, A1 = A2 =  20 dB; phase differences = 0°, 45°, 90°, 135°, and 180°. ( after G. V . 
 8.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 a length 13 Barker code for zero doppler shift superimposed upon all possible auto - correlation functions of 13-bit binary sequences. It can be seen that the Barker code  provides the lowest time sidelobe levels of all possible codes.   Allomorphic Forms. 
 Antennas and Prop ., vol. 37,  no.7, pp. 844–850, July 1989. 
 VERTER 4HE LOW 
 It can be shown that  • 00  m1 = I xp(x) dx = x0 m2 = r00  xlp(x) dx = x5 + <r'  • -oo  The probability density of the sum of a large number of independently distributed quanti­ ties approaches the gaussian probability-density function no matter what the individual dis­ tributions may be, provided that the contribution of any one quantity is not comparable with  the resultant of all others. This is the rentral limit theorem. Another property of the gaussian  distribution is that no matter how large a value x we may choose, there is always some finite  probability of finding a greater value. 
 Thefrequency doesnotappearexplicitly inthesearch-radar range equation. However, thelowerfrequencies arepreferred forasearchradarsincelargepower andlargeaperture areeasiertoobtainatthelowerfrequencies, itiseasiertobuildagoodMTI capability, andthereislittleeffectfromadverse weather. Different radarrangeequations can.bederivedfordifferent applications, depending on theparticular constraints imposed. 
 Arlington, Va.,Apr.2123.1975.pp.527-532. IEEEPub!.75CHO939-1AES. 40.Milne.K.:TheCombination ofPulseCompression withFrequency Scanning forThree-Dimensional Radars. 
 ...362 109 The Hard-tube Pulser 367 10.10 Line-type Pullers .... .,373 10.11 Miscellaneous Components 383 CHAP. 11. 
 The third source is typically caused by shadowing, for example, by an aircraft fuselage blocking one of the bistatic paths—transmit- ter or receiver LOS to a scattering center. In general, this divergence results in a bistatic RCS lower than the monostatic RCS for complex targets. Exceptions include (1) some target aspect angles that generate a low monostatic RCS and a high bistatic specular RCS at specific bistatic angles, (2) targets that arc designed for low monostatic RCS over a range of aspect angles, and (3) shadowing that sometimes occur in a monostatic geom- etry and not in a bistatic geometry.92 Ewcll and Zchncr97 measured the monostatic and bistatic RCS of coastal freighters at X band when both the transmitter and the receiver were near grazing incidence. 
 BEAM SCAT 
 The rectangular RF spectrum has become a triangular video spectrum. FIG. 12.10 Spectrum of fading from a homogeneous small patch (a) before and (b) after detection. 
 PASS FILTERS  EFFECTIVELY DIFFERENTIATING THE APPLIED IMPULSE AND HENCE CREATING A TIME 
 Prior knowledge of target behavior sometimes can be used to avoid the serious effects of  low-angle multipath without overly complicating the radar. Since targets of interest will not go  below the surface of the earth, and are limited in their ability to accelerate upward and  downward, radar data indicative of unreasonable behavior can be recognized and rejected. In  some situations, the target might be flying fast enough and the inertia of the antenna may be  great enough to dampen the angle-error excursions caused by the multipath:'7 Another solu­ tion takes advantage of the fact that large errors are limited to a region of low elevation angles  predictable from the antenna pattern and the terrain. 
 Unfortunately, thetests ofthk method were made inconnection with anairborne radar inwhich the scanning rate varied considerably; hence appreciable inertia could not beused. Furthermore, multiple- pulse coding had notbeen adopted atthat time. Asaresult, interference led tosomewhat erratic results. 
 CALLY REDUCED AS ARE THE ERRORS IN THESE MEASUREMENTS -OREOVER  SEVERE STORMS WHICH COULD OTHERWISE NOT BE PENETRATED ALONG AN ORTHOGONAL TRACK  AND HURRICANES WHICH CAN BE PENETRATED BY SUCH AIRCRAFT  CAN BE OBSERVED FULLY BY AN AIRCRAFT OUTSIDE THE REGIONS OF SEVERE WEATHER 6ARIOUS AIRBORNE RADARS EXIST IN THE RESEARCH COMMUNITY FOR DIFFERENT APPLICATIONS  AND USER GROUPS .!3! HAS DEVELOPED THE DUAL WAVELENGTH  CM AND  MM  %$/0 RADAR FOR THE HIGH ALTITUDE %2 
 MAP %ARTH FROM SPACE v  !VIATION 7EEK AND 3PACE 4ECHNOLOGY     PP   3EPTEMBER    #OVER 3TORY .   39.4(%4)# !0%2452% 2!$!2   £Ç°ÎÇ  * ' &LEISCHMAN  3 !YASLI  % - !DAMS  $ 2 'OSSELIN  - & 4OUPS  AND - ! 7ORRIS   h&OLIAGE PENETRATION EXPERIMENT v SERIES OF THREE PAPERS    )%%% 4RANSACTIONS ON !EROSPACE  AND %LECTRONIC 3YSTEMS  VOL   NO   PP   *ANUARY  4HIS SERIES OF PAPERS WAS  AWARDED THE  - "ARRY #ARLTON !WARD SEE  )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONIC  3YSTEMS  VOL   NO   P   /CTOBER    & 4 5LABY  2 + -OORE  AND ! + &UNG   -ICROWAVE 2EMOTE 3ENSING    6OLUMES  .ORWOOD  -!  !RTECH (OUSE    % , !YERS  * - 2ALSTON  2 0 -AHONEY  0 ' 4OMLINSON  AND * -C#ORKLE  h!NTENNA MEA 
 However, when the absolute detuning becomes excessive, moving targets will belost owing totheir high video spectrum, asisexplained inSec. 16.5. This type ofdetuning isparticularly insidious. 
 Aplotofthesingle-polarization brightness temperature orspacetemperature duetoboth cosmicnoiseandatmospheric' absorption 'isshownbythesolidcurvesofFig.12.11.An ambient temperature of260Kis'assumed inthecomputation ofatmospheric-absorption noise.Atthehigherfrequencies (Xbandorabove)atmospheric absorption isthepredominant contributor tothebrightness temperature,while atthelowerfrequencies (Lbandorlower), thecosmicnoisepredominates.; There"existsabroadminimum inthebrightness temperature extending fromabout1,000to"1O,000'.MHz. Itisinthisregionthatitisadvantageous to operatelow-noise receivers to'achieve' maximum systemsensitivity. Theminimum atmo­ sphericabsorption occurswhenthe"antenna'is vertical(pointed atthezenith),whilethe. 
 REPETITION 
 JOI. Cottony, H. V., and A. 
 ING PULSE 
 The methods of  approximation relate to the two methods of formulating the GBVP: 1. Small-amplitude approximations (sea waveheights much smaller than the radar  wavelength) are used ab initio  with Rayleigh’s hypothesis, in which the surface  boundary conditions are employed to match an angular spectrum of outgoing plane  waves to the incident field.94–96 2. A general integral formulation based on Green’s theorem is pursued either in a  small-amplitude approximation6,97 or under the assumptions of physical optics  (surface curvatures much greater than the radar wavelength).98–100 ch15.indd   27 12/15/07   6:17:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The range measurement is usually the most  significant a radar makes. No other sensor has been able to compete with radar for determin·  ing the range to a distant target. A typical radar might be able to measure range to an accuracy  399 . 
 368 THE MAGNETRON AND THE PLTLSER [SEC. 10.9 previously described quiescent state assoon ascurrent can flow through L,RZtobring thepoint A’back Loground, and assoon asrecharging cur- rent can flow slowly through LItoreturn COtoitsfully charged condition. During the pulse, the potential ofCO(and hence the voltage across the load) slowly declines unless C,ismade very large. 
 12.9 MICROWAVE-RADIATION HAZARDS  High power microwave energy can produce spectacular effects. It has been reported for  example, that 50 kW of UHF power radiating from the open end of a 6- by 15-in. waveguide  will cause ordinary light bulbs to explode, fluorescent lamps many feet away to light up, and a  piece of steel wool to explode into arcs.62 It is not surprising, therefore, that microwave  energy, if of sufficient intensity, is a health hazard and can produce biological damage  n humans. 
 The technique does require  many diodes, and the phase shifters are typically large and bulky as compared with the  switched-line and hybrid-coupled techniques. ch13.indd   51 12/17/07   2:41:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 R. S. Raven, Correction to “Requirements for master oscillators for coherent radar,” in Proceedings  of the IEEE,  vol. 
 Shrader34 © IEEE 1968 ) FIGURE  2.65 Mean improvement factor restriction versus amount of limiting and clutter  spectral spread for a three-pulse canceler  (after T. M. Hall and W. 
 Average value of a'. A composite average of sea clutter data is shown in Fig. 13.3.' This is a  plot of the mean cross section per unit area, a', as a function of grazing angle for various  frequencies and polarizations. 
 Of course the switched LO can also suffer from imperfec - tions, but only one local oscillator is needed, as opposed to hundreds of receivers.  Whichever design path is followed, the demands on receiver linearity and spurious- free dynamic range are extreme. There are five dominant mechanisms known to degrade HF radar receivers: the  nonlinear processes of analog-to-digital conversion, out-of-band inter-modulation  (IMD), cross-modulation, and in-band inter-modulation, and the pseudo-linear pro - cess of reciprocal mixing. 
 C. Hansen, “Aperture theory,” in Microwave Scanning Antennas , vol. I, R. 
 This might be accomplished with  Ratio of clutter spectral width to pulse repetition frequency (uc/fp)  Figure 4.35 Solid curves show the improvement factor of a three-pulse canceler limited by platform  motion [Eq. (4.39)]. Dashed curves show the effect of the DPCA compensation. 
 WIDTH JITTER !MPLITUDE JITTER IN THE TRANSMITTED PULSE ALSO CAUSES A LIMITATION OF   )! ! LOG$D"    WHERE !  IS THE PULSE AMPLITUDE AND  $! IS THE PULSE 
 Signal Process. 2007 ,55, 4162–4172. [ CrossRef ] 8. 
  
 In many applications, however, it is convenient or necessary to employ "mixed" units. Moreover, it is usually more convenient to express the wavelength X in terms of the equivalent frequency in megahertz. It is also desirable to combine all the numerical factors and the various unit-conversion factors into a single numerical constant. 
 Complementary Sequences. Complementary sequences consist of two sequences of the same length N whose aperiodic autocorrelation functions have sidelobes equal in magnitude but opposite in sign. The sum of the two autocorrelation functions has a peak of 2N and a sidelobe level of zero. 
    
 35.Mavroides. W.G.:Weather Tracking withtheAFCLExperimental 3-DRadar,AFCRL-70-0006. Air ForceCamhridge Research Lahoracories, Instrumentacion Papersno.163.January. 
 33  The ferrite Faraday rotator, which was mentioned above as being a part of the dual-mode  phase shifter, also has been applied as an electronic phase shifter.33·38 It is the equivalent of the  mechanical Fox phase shifter.39 Other examples of phase shifters are a helical slow-wave  structure either surrounded by or surrounding a ferrite toroid,40·41 a transversely magnetized  slah of ferrite in rectangular waveguide,42·43 a bucking rotator phase shifter,44 circular polari­ zation between quarter-wave plates,44 a reciprocal, polarization-insensitive phase shifter for  reflectarrays,45 wideband phase shifters,46 and phase shifters that operate at UHF.47 Ferrites  have also been used in continuous aperture scanning where a phase change is provided across  an aperture without subdividing it into separate elements. In one experimental design,48 ten  discrete phase-shifter elements were replaced with a single ferrite-loaded aperture whose  properties were externally controlled to scan the beam radiated by a five-wavelength, X -band  antenna.  Other electronic phase shifters. 
 More details about this optical ﬂow algorithm can be found in Ref. [ 31]. 2.5. 
 SCAN FEED. 
 H. Kushel, “VHF/UHF. Part 2: operational aspects and applications,” Electronics &  Communications Engineering Journal , vol. 
 Dashedcurveisabsorption duetowatervaporinanatmosphere containing 1percentwater vapormolecules (7.5gwater/mJ).Thesolidcurveistheabsorption duetooxygen.(FromBurrowsarid Artwood5andStraiton andTolbert.46). 460 INTRODUCTION TO RADAR SYSTEMS  Radar-to-target distance, nmi  (a)  1 .I  10 10,000  0 9  08 5000  m 3000  07 2 000  i  I? + 0 1000 2 06 900 u 800  700  $05 600  ? 500 0 5 0.4 400  0.3 300  0.2 200  0 1 ,100  0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300  Radar- to-target d~stonce, nmi  (6)  Figure 12.10 Attenuation for two-way, radar propagation as a function of range and frequency for  elevation angle and (b) 5" elevation angle. (From Blake?') , (a) zero  460INTRODUCTION TORADAR SYSTEMS 10,000 5000 3000 2000 N I ~ >; uc ~0' ! 2003005"0o 500a:100 900 800 700 600 400---~./ /V 1/ / V--......---f-- v::::::----~/ ~./ /~VV'e::::::/ .......-:;~ I -/~'/%e::--~- -/~l---~V---1/~~/..-~/~~ ~--~.-"l--- /~~~~r::::V--~--~yf...--l--- ~~c::::-~v-v-e--- ::::---:~~::.--- 1206.0 1.5 05455.0 1.05.5 00 o20406080100120140160180200220 240 260280300 Radar-Io-Iarget distance, nmiCD40 "0 C235c:>c Q) 1520 >- ~b2.5 ~I- (a) o"0 Ca:0,000 300 1002005000 3000 2000 400N I 1000 ~ 900800700600 5001 ~---./ /V /---'"""/~---~./I---V~::::---/:--/~~:::::-- --- ~-0---w:&,~:::----- J---./'".---/!lI~%'/vl----V- ~~/',/""f----....-~ ~~~~~--.-.-.--09 0.1CD ~07 .Qo206 Q) E ~05 ~ Io ~0.40.8 0.31.1 1.0 0.2 a20406080100120140160180200 220 240260 280 300 Radar-Io-targel dislance, nmi (b) Figure11.10Attenuation fortwo-way, radarpropagation asafunctionofrangeandfrequency for(a)zero elevation angleand(b)S°elevation angle.(FromBlake.·'). 
 The simplest method is to mix the signal from the IF amplifier with the signal used in the sidestep. This reduces the spillover signal to dc and the clutter signal to dc and very low frequencies. A multipole filter will suppress those unwanted signals with minor suppression of the very lowest dopplers. 
 Indescribing thegeometry ofsurfaceclutter,theincidence angleandthedepression angle aresometimes lIsedinsteadofthegrazing angle.TheseareshowninFig.13.2.Theincidence angleisdefinedrelative tothenormaltothesurface; thegrazingangleisdefined withrespectto thetangent tothesurface, andthedepressiofl angleisdefinegwithrespecttothelocalhorizon­ talattheradar.Whentheearth'ssurfacecanbeconsidered flat,thedepression angleandthe grazing anglearethesame.Whentheearth'scurvature mustbeconsidered, thesetwoangles arenotequal.Theincidence angleispreferred whenconsidering earthbackscatter effectsfrom nearperpendicular incidence, asinthecaseofthealtimeter. Thegrazingangleisthepreferred measure inmostoftheotherradarapplications, andwillbetheangleusedinthischapter. Descrintions presented inthischapterofradarscattering fromthelandandtheseaareby nomeanscomplete. 
 The  elevation patterns for each single row  have poor sidelobes, but several rows  are used for each receive beam thereby  improving the elevation sidelobes. For  transmit, all 24 rows (the whole array)  are used. On receive, 9 groups of rows  are used to form 9 receive beams. 
 H. Howe, Stripline Circuit Design , Norwood, MA: Artech House, 1974, pp. 77–180. 
 Usually the round-earth geometry must be considerl·d.  which results in a more complex formulation than the simple expression given above.  14.3 ELECTRONIC COUNTER-COUNTERl\1EASURES  All radars, civilian and military, must be able to operate in the crowded electromagnetic  environment that results from the transmissions of other radiating sources. 
   
 It is possible, however, to utilize matched­ filter processing in the FM-CW radar in a manner similar to that employed with FM (chirp)  pulse compression radar as described in Sec. 11.5, and thus overcome the lower sensitivity and  multiple-target problems. JR.39 As the duty cycle of an FM pulse compression waveform in­ creases it becomes more like the FM-CW waveform of unity duty cycle. 
 Figure 9. Comparison for imaging performance of four approaches under different sparsity samplings. 4.1.5. 
 The necessary thickness ofthe screen tends toblur the edges ofthe signals and thus reduce contrast gradient, asdoalso limitations inthesharpness offocus oftheelectron beam. Many screens also have acertain amount ofgraininess which contributes tothe reduction ofcontrast gradient. Contrast between signals ofdifferent intensities isespecially impor- tant inoverland flying, where itisessential tobeable todistinguish land from water and atthe same time tohave good contrast between weak echoes from ordinary terrain and the much stronger ones from built-up areas. 
 Although thebasictheoryofradarwavepropagation maybewellunderstood, accurate quantitative predictions arenotalwayseasytoobtainbecauseofthedifficulty inacquiring the necessary knowledge oftheenvironment inwhichtheradaroperates. Insomerespects, the prediction ofpropagation phenomena islikepredicting theweather. Quiteoftentheradar systemdesigner mustbecontent withonlyaqualitative knowledge of"average" propagation effects.Nevertheless, itisimportant toknowandunderstand howpropagation phenomena caninOuence radarperformance sinceitcanbeamajorfactorindetermining howwellaradar performs"in aparticular application.. 
 Thus the antenna beams are generated by computation. Its practical  implementation rc4uires converting RF or IF signals at each element to digital numbers.  S)stem considerations. 
 The maximum power gain of an antenna is equal to its directivity (maximum directive gain) multiplied by its radiation efficiency.19 The directivity D is defined in terms of the electric-field-strength pattern £(6,4>) by the expression D = 2, , 4^""" (2.13) J j£2(6,<|>) sin 6 d9 d$ o o where 6 and <t> are the angles of a spherical-coordinate system whose origin is at the antenna and £max is the value of £(0,4>) in the maximum-gain direction. The radiation efficiency of the transmitting antenna is the ratio of the power input at the antenna terminals to the power actually radiated (including minor- lobe radiation). In terms of the receiving antenna, the equivalent quantity is the ratio of the total signal power extracted from the incident field by the antenna, with a matched-load impedance, to the signal power actually delivered to a matched load. 
 itisdifficultto obtainstableoperating characteristics withlonglifeinsealed-off tubes.Theswitching proper­ tiesofaferritecirculator canalsobeusedforconstructing adigitally switched, nonreciprocal phaseshifter. 54Itisnotoftenused,however, because ofitshigherloss,lowerpeakpower,and highercostascompared withdigitally switched diodephaseshifters. Ferroelectric phase shifters. 
 AND( 
 &- WAVEFORM IS DESIRED  THE PHASE SAMPLES FOLLOW  A QUADRATIC PAT 
 43 Terrain database and radar, 5.30 Terrain following, 5.28 to 5.29 Terrain height estimation, 5.29 to 5.30 Terrain scattered interference, 24.43 TerraS AR-X, 18.12 Test ranges, indoor, 14.32 to 14.35 Test ranges, outdoor, 14.30 to 14.32 THAAD radar, 13.68 Thunderstorm prediction, 19.32 Time-delay scanning, 13.7 Time-frequency coded waveforms, 8.25 to 8.26 Topex altimeter parameters, 18.35 T ornado detection, 19.28 to 19.29 Towed decoy, 24.8 T/R module, 10.28 Track association, 7.38 to 7.41 Track file, 7.23 to 7.25 Tracking, automatic, 7.22 to 7.46 Tracking radar, 1.6 acquisition with, 9.20 to 9.21 automatic gain control (AGC), 9.33 to 9.35 conical scan, 9.16 to 9.17 dual band, 9.24 to 9.25 and ECCM, 24.43 error reduction techniques, 9.46 to 9.47 errors in, 9.26 to 9.46 external causes of error, 9.37 to 9.42 glint in, 9.30 to 9.35, 9.47. limitations in performance, 9. 44 to 9.45 monopulse, 9.3 to 9.16 two-channel, 9.14 to 9.15 multipath error reduction, 9. 
 Conf. on Radar, RADAR 2003 , Adelaide,  September 2003. 159. 
 This will give 200/1 15bus voltages. Preliminary tests indicate that such systems, especially those having several large generators inparallel, will bestable, reliable, and directly usable forradar. 1 Summary ofAlternatives toDirect-driven Alternators.—If direct- driven alternators cannot beemployed inany given case, orifthepower requirements are sosmall astorender aspecial generator impractical, there arefive alternatives: 1.Motor-alternator sets. 
 Harmening, “A laser-based, near-field probe position measurement system,” Microwave J .,  pp. 91–102, October 1983. 17. 
 105--115, March. 1975.  32. 
 They both use the doppler frequency shift to  extract moving targets in clutter. A high PRF pulse doppler radar  has no ambigui - ties (blind speeds) in doppler, but it does have range ambiguities. A medium PRF  pulse doppler radar  has ambiguities in both range and doppler. 
 P.: Doppler Wave Recognition with High Cluttei Rejection. IEEE Trut~s., vol. AES-3  Supplement, no. 
 In practice, the  active array elements are turned on one at a time in coordination with the probe posi - tion. Some examples of existing systems that use near-field ranges to perform factory  calibration are THAAD and SAMPSON.108,109 ch13.indd   60 12/17/07   2:41:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 J. Keeler and C. A. 
 42 
 ( after J. R. Riley18 © IEEE 1985 ) ch14.indd   12 12/17/07   2:46:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 however, is a powerful point source of radar energy which can provide more than adequate angle information for homing. All that is required is a means to allow the seeker angle track circuits to process the noise energy. When the jamming is such that tracking of the target skin return is not possible, the seeker switches to passive tracking of the received jamming energy. 
 SHADOWING MODEL  FOR UPWIND AND DOWNWIND DIRECTIONS  4HIS MODEL IMPLIES A SHARP DECREASE IN THE  AVERAGE CROSS SECTION FOR GRAZING ANGLES BELOW A FEW DEGREES )N CROSSWIND DIRECTIONS WITH THE RADAR LOOKING ALONG THE TROUGHS OF THE MAJOR WAVES  A  MUCH MILDER SHADOW 
 Brown, and B. Jaracz: Multi-Octave Double-Balanced Mixer, Microwm,e J., vol. 16, pp. 
 3.Those inwhich both wavefronts areexternally induced. Inthis class arethe “squaring amplifier, ”which produces square waves from sinusoids orother waveforms, and various triggered devices. The latter can bedivided into two classes: (a)the “flopover” or “lockover, ‘‘inwhich anexternal signal induces achange from one stable state toanother, and areverse signal orone from asecond source reverses theoperation (Fig. 
 SPACE-BASED REMOTE SENSING RADARS  18.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 waveform is a step function, whose rise time is equal to the compressed pulse length  and whose position on the time-delay axis is determined by the altimeter’s height. If  the sea surface is modulated by waves, the altimetric depth of the surface increases,  which reduces the slope of the waveform’s leading edge. Hence, SWH is proportional  to the waveform rise time. 
 Radar antenna gimbal designs vary greatly depending upon scan rate,  FOV , tracking requirements, antenna size, mass, etc. Basic Feeds.35,36 For radars requiring a simple pencil beam, basic single mode  waveguide horn feeds such as pyramidal (TE01 mode) and conical (TE11 mode) horns are  widely used. Single-mode, flared horns will provide linearly polarized pencil beams and  will generally handle high power. 
 [ CrossRef ] 28. Khwaja, A.; Ferro-Famil, L.; Pottier, E. SAR raw data generation using inverse SAR image formation algorithms. 
 Temes. C. L.: Sidelobe Suppression in a Range-Channel Pulse-Compression Radar, IRE Trans.. 
 Rodrigue, G. P.: Microwave Solid-State Delay Line, Proc. IEEE, vol. 
  
 4IME !DAPTIVE 0ROCESSING   2 +LEMM ED   ,ONDON )%% 2ADAR  3ONAR  AND .AVIGATION  3ERIES     PP n  7 $ "LAIR  ' ! 7ATSON  4 +IRUBARAJAN  AND 9 "AR 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.68  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 Terminal High Altitude Area Defense (THAAD). 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 where Si is the average background level, Xi is the return in the ith cell, K is the feed - back value that determines the map time constant, and A is the constant that determines  the Pfa. 
 Measurements oflocal-oscillator stability at 3cm, asreported below, show that this system ofstabilization might be adapted toMT1. TABLE 16.5.—TYPIcAL LOCAGOSCILLATOR STABILITIES ( Description ofoscillators compared. (cf.Sec.Frequency averageFrequency band 16.21) of~,(Kc/secZ) tohalf-power, cps Two identically shock-mounted type 417re- 79 1300 flexklystrons (10cm) without stabilizing 61 250 cavities 50 140 Two identical type 2K28 reflex klystrons (10 168 I1300 cm), without stabilizing cavities, inaquiet 100 250 roomI I Same tubes asabove, onestabilized 1137 I1300 6S 250 Same tubes, both stabilized 1.4 250 1.4 140 TWO other stabilized tubes ofsame type ina 3 250 quiet room (more typical value) Two such oscillators; 60cps a-cheater power 36I250 used forone Two such oscillators operating inan SCR- 10 584 truck Two such oscillators operating inthe radio 70 compartment ofaB-17 aircraft after some- what improved shock mounting Two type 2K25 reflex klystrons (3cm) inthe 20 laboratory with echo-box frequency control :Described indetail inChap. 
 For 0 # 0, the bear11 shape is not symmetrical about the center of the beam, but is  eccentric. I'hus the bean1 direction is slightly different from that computed by standard for-  r~ttllas. In addition to the changes in ttie shape of the main beam, the sidelobes also change in  appearance arlci positiori. 
  AND 0$      .UMBER OF 0ULSES )NTEGRATED,OSS FOR 6ARIOUS .UMBERS OF 2EFERENCE #ELLS IN D"     c                                          AFTER 2 , -ITCHELL AND * & 7ALKER Ú )%%%  . 
 For this reason, various schemes forreducing the gain automatically and rapidly have been devised. These arevariously called “instantaneous automatic gain control (IAGC),” “amplified back-bias,” “back-bias,” etc. The circuit shown inFig. 
 On receive, with the spark gaps open circuit, the path between antennasand transmitter would appear high impedance with a low impedance seen by the receive path. The antenna switch would alternately short-circuit the half-wave stubs connected to the port and starboard antennas, causing the path to those antennas toalternately appear high impedance, with transmission or reception on the other antenna. The lower part of the aerial switch unit, shown in ﬁgure2.19(b) was used to synchronously switch the receiver output between left and right CRT plates. 
 They can,  however, be used by a bistatic hitchhiker to identify and locate a suitable transmitter.  Thus, although they have many requirements and characteristics common to multi - static radars, they are not radars and will not be considered here. *  The foregoing describes multistatic operation that combines data noncoherently. 
 The refocused results of ship01 with the three methods are shown in Figure 6. The original sub-image, DCT and PGA results are respectively depicted in Figure 6a–c. The result with the proposed method is shown in Figure 6d. 
  
 Eng.,  vol. OE- II, pp. 158–163, April 1986. 
 Common PWM does not usually occur. However, if it does, it has requirements similar to those of common PPM. Also, pulse-amplitude modulation (PAM) can occur but is usually negligible when the other requirements are satisfied. 
 However, if two signals are present simultaneously, and if one  is much larger than the rms noise level at the limiter output, the weaker signal will be  suppressed by the stronger over the time interval that they overlap. The result is that the  probability of detecting the weaker signal is degraded.42 The hard limiting of superimposed  echoes in pulse-compression radar may also cause the generation of false targets in addition to  small-signal suppression.43  Pulse tx)mpression has also been used in conjunction with frequency-scan radar to  achieve improved range resolution.44 This was discussed briefly in Sec. 8.4. 
 RANGE SEARCH 623  AT THE EXPENSE OF POORER LONG 
 (The three coordinates can thus be obtained with two 2D-radars.) Such a height  finder would be directed by the 2D air-surveillance radar lo the azimuth of the target. It then . 542 INTRODUCTION TO RADAR SYSTEMS  scans its horizontal fan beam in elevation to make an elevation angle measurement of the  target found at the range designated by the air-surveillance radar. 
 A floodlight beam can be used with either transmitter or  receiver. The floodlight transmitter remedy requires a dedicated transmit antenna that  is designed to flood the surveillance sector continuously. The receiver then scans the  sector with a high-gain antenna. 
 TERISTICS MAY VARY AS A RESULT OF CHANGES IN THE GROUND SURFACE ELECTRICAL PARAMETERS !NY PROCESSING SCHEME THAT ASSUMES THE ANTENNA PARAMETERS REMAIN CONSTANT NEEDS TO ACCOUNT FOR THE MODE OF OPERATION OF THE ANTENNAS AND THE DEGREE OF STABILITY THAT IS PRACTICALLY REALIZABLE 4HIS IS A PARTICULAR ISSUE FOR '02 AND NEEDS CAREFUL ATTENTION TO REDUCE THE EFFECT OF ANTENNA 
 8. Parzcn. E.: "Modern Probability Theory and Its Applications," John Wiley & Sons, lnc., New York,  1960. 
 Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar.  PULSE COMPRESSION RADAR  8.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 between 0 ° and 180 ° in accordance  with the sequence of elements, 0s and  1s or +1s and −1s, in the phase code,  as shown in Figure 8.15. Because the  frequency is not usually a multiple of  the reciprocal of the subpulse width,  the coded signal is generally discon - tinuous at the phase-reversal points  This does not impact its time side- lobes, but does cause some increase  in the spectrum sidelobe levels.17 Upon reception, the compressed pulse is obtained by matched-filter processing. 
 FIG. I2.6b In-phase addition for Bragg scattering; A/? = n\/2. \ = 2hR between the source and two successive wave crests, the phase differ- ence between the echoes from successive crests is 360°; so the echo signals all add in phase. 
 For new radar systems, system designers have been motivated by  these considerations to choose as high a duty cycle as possible, both to reduce the peak  power required and to permit using solid-state devices at a reasonable cost. The decision to use a high transmitter duty cycle, however, has significant impact  on the rest of the radar system. Operation at a high duty cycle generally requires the  use of pulse compression to provide the desired unambiguous range coverage together  with reasonably small range resolution. 
 The device estimates the standard deviation of the correlated samples with the mean de- viate estimator, where extraneous targets in the reference cells have been excluded from the estimate by use of a preliminary threshold T2. The rank and MGST detectors are basically two-sample detectors. They decide that a target is present if the ranks of the test cell are significantly greater than the ranks of the reference cells. 
 Ground-plane imagery with  minimal distortion is necessary if comparison is to be made with maps or with imaging  taken from other sensors, such as optical sensors or other SARs. ch17.indd   12 12/17/07   6:48:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 ( 11.3) is proportional  to the rise time and is independent of the pulse width. An improvement in accuracy is ob­ tained, therefore, by decreasing the rise time (increasing the bandwidth) or increasing the  signal-to-noise ratio.  The actual estimate of the time delay obtained by determining when the leading or  trailing edge of the pulse crosses a threshold will depend on the value of the threshold relative  to the peak value of the pulse. 
 352 INTRODUCTION TO RADAR SYSTEMS  higher frequencies. The transistor is generally used in a multistage configuration with a  typical gain per stage decreasing from 12 dB at VHF to 6 dB at K11 band. 10 In the GaAs FET,  the thermal noise contribution is greater than the shot noise. 
 RESPONSE FILTER  WITH THE FREQUENCY RESPONSE SHOWN IN LINE  OF &IGURE   IS A HALFBAND FILTER BECAUSE THAT FREQUENCY RESPONSE AND A VERSION SHIFTED IN FREQUENCY BY HALF A PERIOD SUM TO A CONSTANT 4HIS PROPERTY CAUSES ALMOST HALF OF ITS IMPULSE 
 This ECCM technique pertains to the realm  of waveform coding.3,136–137  The ambiguity function (AF) is the tool to characterize waveform coding in terms  of resolution, sidelobe level, and ambiguity.137 In selecting a waveform for a given  radar application, the AF should be tested against the environment in which the radar  ch24.indd   31 12/19/07   6:00:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 20. Emery, F. E.: Low Noise GaAs FET Amplifiers, Microwave J., vol. 
 Organizing the data samples into probability distributions makes the median (50 percent) value a convenient statistical measure of the clutter cross section. But many investigators process their data to provide the mean value, and since the conversion of a median to a mean requires knowledge of the probability dis- tribution function, care must be taken to avoid ambiguity in comparing the mea- surements of different experimenters. The original analysis of the NRL 4FR data was based on median cross sections and the assumptions of the cookie-cutter an- tenna beam embodied in Eqs. 
 Limited communications also can be effected by  this means. Tlie cost of an ff F OTH radar for the detection of aircraft might be expected to be  Iiigli relative to tlic cost of a colivelitional microwave radar, but on the basis of cost per unit  area of coverage it is quite competitive.. Its chief advantage is that it can cover areas not  rc;isihle wit11 corivcritiot~al rndats. 
 The 42-element S-band array scanned a ± 9 degree sector at a rate of 10 per second.  Related devices that obtain phase change by relative rotation of crossed dipoles in a circular  guide or cavity are described by Kummer. 51  A different form of mechanical beam steering is used in an array with spiral antenna  elements. 
 Abouzahra and R. K. Avent, “The 100-kW millimeter-wave radar at the Kwajalein Atoll,”  IEEE Antennas and Propagation Magazine , vol. 
 P. Murray, “Electromagnetic capability,” Chap. 29 in Radar Handbook , 1st Ed., M. 
 DPR . The dual-frequency precipitation radar is the active microwave instru - ment156 for the Global Precipitation Measurement (GPM) Core Observatory. DPR is  based on a Ku band instrument (KuPR) similar to its predecessor on TRMM, augmented  by a Ka band (35.55 GHz) radar (KaPR). 
 TO 
 Remote Sens. Lett. 2009 ,6, 757–761. 
 ANALOG CONVERTER $!# OR $! CONVERTER  AND FILTERED ! VARIETY OF WAVEFORM TYPES EG  ,&-  .,&-  AND #7 WAVEFORMS  CAN BE GENERATED IN THIS WAY BY USING THE APPROPRIATE PHASE MODULATION CHAR 
 DEPENDENT &OR THE GENERAL BISTATIC CASE  WHERE  ,     THE  FREE 
 INDICATION -4)  IMPROVEMENT FACTOR 4HE SIGNAL 
 The 16 coefficients can be expressed  by 8 remaining coefficients through mutual sequential substitution, due to the relationship from Equation (11.14).  A favourable solution is given with Equation (11.14).   € C[]=c11c32⋅c42 c22c32⋅c11 c33c33⋅c42 c22 c31⋅c41 c11c22c33⋅c41 c11c31⋅c22 c33 c31 c32 c33c32⋅c31 c33 c41 c42c42⋅c41 c44c44                                 (11.14)  Beginning from equation (11.14) to (11.13) leads to a solvable homogeneous set of equations  with 8 unknown quantities. 
 Therefore, it can be expected that dipoles in line will be loosely  coupled and parallel dipoles will be tightly coupled. When an element is placed in an  array of many elements, the effects of coupling are sufficiently strong that the pattern  and impedance of the elements in the array are drastically altered. ch13.indd   20 12/17/07   2:39:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 PHASE ADDITION FOR "RAGG SCATTERING $2   NK  . 
 ch22.indd   30 12/17/07   3:02:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 
 The basic structure of the classical form of the magnetron is shown  in Fig. 6.1.' The anode (I) is a large block of copper into which are cut holes (2) and slots (3).  The holes and slots function as the resonant circuits and serve a purpose similar to that of the  lumped-constant LC resonant circuits used at lower frequencies. 
 76.Jordan. E.c.:"Electromagnetic WavesandRadiating Systems," sec.12.17,Prentice-Hall. Inc., Englewood Cliffs,N.1..1950. 
 FIG. 16.13 Simplified double-delay DPCA mechanization. single-pulse combination, the actual double cancellation can be performed by any of the processing techniques outlined in Chap. 
 The AN/SPS-48 radiates  multiple freqiiericies so as to generate simultaneous multiple beams to permit a higher scan  rate than would be possible with a single bearn. Since the range to the target is less as the  6,  Snake  feed  I - C  Figure 8.16 Planar-array frequency scan antenna  consisting of a folded-wavelength delay-line feeding  a set of linear waveguides that are so oriented  that radiating slots in the narrow wall of the guide  lie in the plane of the antenna.63  IIII'FLITTRONICAI.I.Y STEERED PHASED ARRAY ANTENNA INRADAR301 IIispossiblc forafrcqucncy-scan array10cmploydifferent frequencies toradiateoverthe sameangular region. assuming thattheantenna·feedand elements aresufficiently broadband.64Thiscanbeseenfromanexamination ofEq.(8.17b). 
 PROTECTION FOR THE LOW 
 DEPENDENT  BUT OVER TIME  IT IS CONSTANTLY MOVING TOWARD THE FRONT END OF THE SYSTEM Óx°ÈÊ -1  ,9 4HE PURPOSE OF THIS CHAPTER WAS TO PROVIDE AN OVERVIEW OF HOW DIGITAL SIGNAL PROCESS 
 252–264, February 1985. 29. E. 
 Smith for notes on radar  navigation systems, to Dr L. Huxley for information on  basic radar principles, to the Publication Board of the  Radio Research Laboratory at Harvard University, and  to the directors of the research laboratories of A. C.,  Cossor, Ltd, and the General Electric Co., Ltd. 
 . 
 78. Woodward. P. 
  HAS UNIQUE FEATURES THAT DICTATE ITS USEFULNESS FOR A GIVEN RA DAR  APPLICATION )T REPRESENTS ONE OF THE FEW ANALOG PROCESSING DEVICES USED IN MODERN RADAR 4HE ADVANTAGES OF THE 3!7 DEVICE ARE ITS COMPACT SIZE  THE WIDE BANDWIDTHS THAT CAN BE ATTAINED  THE ABILITY TO TAILOR THE TRANSDUCERS TO A PARTICULAR WAVEFORM  THE ALL 
 Elachi, and F. T. Ulaby: Microwave Remote Sensing from Space, Proc. 
 However, when a radar is operated  i111der field cotlditions. the performance usually deteriorates even more than can be accounted  for. hy the above losses, especially when the equipment is operated and maintained by inexper-  icilccd or urtillotivatcd ~~crsotirlel. 
 S-ormally, the desired d-c voltages are obtained from ana-csupply bythe use oftransformers and rectifiers, either ofthe thermionic orofthe dry-disk type. Power supply design varies with the application, and differs foraircraft installations, ground system installations, and ship installations. AIRCRAFT SYSTEMS Radar power inaircraft should, ifpossible, beobtained from directly- generated alternating current., Where this isnotpracticable, means exist toconvert low-voltage direct current from the aircraft electrical system tothedesired type ofsupply voltage. 
 KT NORTHERLY BLOWING AGAINST THE CURRENT WILL RAISE A SEA THREE TIMES AS HIGH AS A  
 Radomes arenotwidely used tohouse shipboard scanners, the tendency being tomake the antennas ofsuch low wind resistance and such sturdy construction asto render radomes unnecessary. Ground-based radars may begrouped, according totheir mobility, astransportable, mobile, and fixed. Because thetransportable scanners are disassembled for moving, their installation requirements include easy assembly. 
 Actual Earth surfaces are too com - plex to be described adequately in any of the models, and the effects of signals that pen - etrate the ground and are scattered therein are too little known to permit its evaluation. 16.4 FADING OF GROUND ECHOES The amplitude of ground echoes received by radars on moving vehicles fluctuates  widely because of variations in phase shift for return from different parts of the illumi - nated area. In fact, even fixed radars frequently observe fluctuations in ground echoes  because of motions of vegetation, wires blowing in the wind, etc. 
 100.Hering, K.H.:TheDesignofHybridMultiple BeamForming Networks, ..PhasedArrayAntennas," A.A.OlinerandG.H.Knittel(eds.),ArtechHouse,Inc.,Dedham, Mass.,1972,pp.240-242. 101.Cottony, H.V.,andA.C.Wilson: AHigh-Resolution Rapid-Scan Antenna, J.Res.Nail.Bur.Sid., vol.65D,pp.101-110, 1961.. I Ill. 
 vol.AP-24,pr.269276, May,1976. 52.Ulahy.F.1'..and1'.F.Rush:CornGrowth asMonitored byRada•.IEEETrailS.,vol.AP-24.pp. 819-828. 
 260–264. 126. D. 
 (8.34) Time-domain weighting is utilized in the spectral analysis processing to reduce  the time sidelobes of the compressed pulse and improve the resolution performance  when multiple targets are present within the range window. As an example, the use of  Hamming time-domain weighting reduces the peak time sidelobe level from –13.2 dB  to –42.8 dB with an increase in the 6-dB frequency resolution width to ∆f6 = 1.81/ T.  The 6-dB range resolution width for Hamming weighting is  ∆Rc B61 812=. 
 10000 101001000 150000 10 100 300 30© 1994 Deneba Systems, Inc.σ/m2 R    Figure 13.21  Typical reflection cross -section for a 76 GHz Acc Radar sensor.     In the literature [Cur, TaK] there are given the flowing values found in the table below.    . 
 ARRIVAL ANDOR DIFFERENTIAL DOPPLER MEASURE 
 NENTIAL HORN 4HE IMPULSE RESPONSE OF THIS CLASS OF ANTENNAS GENERALLY RESULTS IN A WAVEFORM WHOSE TIME FREQUENCY RESPONSE IS EXTENDED AND IS SIMILAR TO A CHIRP  ALBEIT WITH AN INCONSTANT AMPLITUDE  IF THE INPUT IS AN IMPULSE %XAMPLES OF NONDISPERSIVE ANTENNAS ARE THE 4%- HORN  THE BICONE THE BOW  TIE THE RESISTIVE  LUMPED ELEMENT 
 6.5 REFLECTORANTENNAANALYSIS In calculating the antenna radiation pattern, it is assumed that the reflector is a distance from the feed such that the incident field on it has a spherical wavefront. There are two methods2'38 for obtaining the radiation field produced by a reflec- tor antenna. The first method, known as the current-distribution method, calcu- lates the field from the currents induced on the reflector because of the primaryFRONTFEEDWAVEGUIDE HORN CUTLER (DUAL) DIPOLE DISK VERTEX(REAR)FEEDS OFFSETFEED CASSEGRAIN FEED GREGORIAN FEED SIMPLY FLARED PYRAMIDAL HORN SIMPLY FLAREDCONICAL HORNCORRUGATED CONICALHORN COMPOUND FLAREDMULTIMODE HORNFINNED HORNSEGMENTEDAPERTURE HORN . 
 Lenses made from artificial dielectrics are generally of less weight than those from solid  dielectrics. For this reason, artificial dielectrics are often preferred when the size of the antenna is  large, as, for example, at the lower radar frequencies. Artificial-dielectric Imses may bz  designed in the same manner as other dielectric lenses. 
 Probability of false alarm =  10 hits integrated.Thecurve labeled  "Rayleigh linear detector" applies  to the conventional receiver with  Rayleigh clutter or noise. The curve  labeled " ChernoK bound" provides  an upper bound to the optimum  detector for the particular clutter  model indicated.  (Afrer ~chleher.'~.~~ courtesy  1 EEE.)  example of one such technique is the log-FTC receiver.32 This is a receiver with a logarithmic  ic~lxit-output cltaracteristic followed by a high-pass filter (one with a fast time-constant, or  FTC). 
 Tlie classical a-/l tracking filter is relatively easy to implement. To handle the maneuver-  ing target, some means may be included to detect maneuvers and change the values of a and fl  accordingly. In some radar systems, the data rate might also be increased during target  maneuvers. 
 SCATTER 2#3 ROLLS OFF FROM  R& 4HE ROLLOFF IS APPROXI 
 Mancon, S.; Giudici, D.; Tebaldini, S. The ionospheric effects mitigation in the BIOMASS mission exploiting multi-squint coherence. In Proceedings of the 12th European Conference on Synthetic Aperture Radar, Aachen, Germany, 4–7 June 2018; pp. 
 10. P. S. 
 J. Dutton. and 8. 
 50. Holbourn, P. E., and A. 
 It is defined as the power averaged over that carrier-frequency cycle which occurs at the  maximum of the pulse of power. (Peak power is usually equal to one-half the maximum  instantaneous power.) The average radar power Pa, is also of ii~terest in radar and is defined as  the average transmitter power over the pulse-repetition period. If the transmitted waveform is  a train of rectangular pulses of width z and pulse-repetition period Tp = l[fp, the average  power is related to the peak power by  The ratio P,,/P,, r/TP, or rfi is called the duty cycle of the radar. 
 FILTER PERFORMANCE FOR ANY RADAR WAVEFORM )N THIS CASE  DISCRETE 
 TO 
 BAND PHASED ARRAY RADAR IS PART OF THE .AVY !EGIS WEAPON  SYSTEM AND WAS DEVELOPED BY 2#!  NOW ,OCKHEED -ARTIN )T HAS FOUR PHASED ARRAY  APERTURES TO GIVE UNOBSTRUCTED HEMISPHERICAL COVERAGE &IGURE    )N ITS EARLY CON 
 9 8 7. 510 INTRODUCTION TO RADAR SYSTEMS  19.5 Hz.97 The wing-beat frequency f in hertz and the length I of the wing in millimeters are  foundg8 to be related byJ0.827 = 572. The term hirdactit~ity nlodrtlation (BAM) has been applied  to the distinctive waveforms obtained from birds." The spectral components of tllc DAM  pattern of a bird in flight are said to be remarkably stableg7 and suited for determining  identity. 
 4The CYCLE is a complete alternation or oscillation from one crest through a trough to the next crest. When the wavelength is 3.2 centimeters (0.000032 km), THE RADAR BEAM The pulses of r-f energy emitted from the feedhorn at the focal point of a reﬂector or emitted and radiated directly from the slots of a slottedwaveguide antenna would, for the most part, form a single lobe-shapedpattern of radiation if emitted in free space. Figure 1.2 illustrates this freespace radiation pattern, including the undesirable minor lobes or SIDELOBES associated with practical antenna design. 
 Itmayevcnapply,tosomccxtcnt,toequipmcnt opcratcd hy professional engineers underadversefieldconditions. Factorswhichcontribute tofielddegra­ dationarcpoortuning.wcaktuhes,waterinthetransmission lines,incorrect mixer-crystal currcnt.dctcrioration ofrcceiver noisefigure,poorTRtuberecovery, loosecableconnections, etc. Tominimize fielddegradation, radarsshouldbedesigned withbuilt-in automatic performance-monitoring equipment. 
 Both  rough terrain and high winds tend to'iricrease atmospheric mixing, consequently reducing the  occurrence of ducting. Radar propagation is normal whenever the upper air is unusually cold  in comparison with the earth's suiface'.'! -"' ,  ,  :,I .. I~~JII~'~~,~~ I : ',[. 
 COS;   = SIN;  VV P VV T T!!E32JT 
 millimeter waves was found to depend on the drop size distrib~tion of the  pricipitation.102 Even though the rain rates were the same, the backscatter from rain contain­ ing drops 2 to 6 mm in diameter was approximately 10 dB greater than rain containing drops  1 mm in diameter or less. The amplitude fluctuations of the rain backscatter were approxi­ mated by a log-normal probability distribution over the range from 9.4 to 94 GHz and at rain  rates from I mm/h to 60 mm/h. The variance (and standard deviation) of the log-normal  distribution was independent of rain rate and decreased with increasing frequency. 
 AP-22, pp. 81-84, January, 1974.  136. 
 Evans: Target-Generated Range Errors, Naunl Research Lahortrrory hlt~ttlor~irr-  dlim Report 2719, January, 1974.  57. Cross, D. 
  2D"     4D"      
 This is because the corner reflector is a reentrant structure, and no matter what  its orientation (within limits, of course), internally reflected waves are directed back  toward the source of the incident wave. A corner reflector is formed by two or three flat  plates intersecting at right angles, and waves impinging on the first face are reflected  onto the second; if there is a third face, it receives waves reflected by the first two  faces. The mutual orthogonality of the faces ensures that the direction taken by waves  upon final reflection is back toward the source. 
 A counterpart ofthis equipment was manufactured inthe United States, being called SCR-521 bytheArmy and ASE bytheNavy. The SCR-521 operates atafrequent yof176 Me/see. Two sets of antennas are provided giving different beam patterns (Fig. 
 Sllciripold. I). If.. 
 Quadratic residue sequences satisfy two of the randomness characteristics: the periodic autocorrelation function is as shown in Fig. 10.100 having a peak of N and a uniform sidelobe level of —1, and the number of Is is approximately the same as the number of Os. A quadratic residue sequence of length N exists if N = 4t — 1, with N a prime and t any integer. 
 Kretschmer, and W. W. Shelton, Aspects of Radar Signal Processing , Dedham,  MA: Artech House, 1986, pp. 
 The discussion in this section applies, for the most part, to linear one­ dimensional apertures or to rectangular apertures where the distribution is separable, that is,  where A(x, z) = A(x)A(z).  The synthesis techniques which apply to array antennas usually assume uniformly spaced  isotropic elements. The element spacing is generally taken to he a half wave-length. 
 BASED RADAR ALTIMETER DESIGNED TO OPER 
 CONDITIONED POWER SUPPLY  THE OVERALL PHASE RIPPLE CAN USUALLY BE ASSUMED TO BE REDUCED BY A FACTOR EQUAL TO THE SQUARE ROOT OF  . IF THE POWER SUPPLY  CLOCKS ARE PURPOSELY NOT SYNCHRONIZED L "ECAUSE OF SATURATION EFFECTS  AMPLITUDE ERRORS IN CASCADED STAGES DO NOT SIMPLY ADD  (OWEVER  AMPLITUDE ERRORS IN DRIVING STAGES WILL CAUSE DRIVE 
 Soc ., vol. 78, pp. 1411–1430, 1997. 
 HORN TRIPLE 
 The runction of the automatic gain control (AGC) is to maintain the d-c level of the  receiver output constant and to smooth or eliminate as much of the noiselike amplitude  nuctuations as possible without disturbing the extraction ,of the desired error signal at the  conical-scan frequency.  One of the purposes of AGC in any receiver is to prevent saturation by large signals. The  scanning modu)ation and the error signal would be lost if the receiver were to saturate. 
 Since the plot of the ambiguity function is often normalized so that IX(O, 0) l2 = 1, the  ambiguity diagram is seldom used to assess the detection capabilities of the waveform.  The accuracy with which the range and the velocity can be measured by a particular  waveform depends on the width of the spike, centered at Ifl, 0)12, along the time and the  frequency axes. The resolution is also related to the width of the central spike, but in order to  resolve two closely spaced targets the central spike must be isolated. 
 For the subaperture reconstruction based on L1regularization, it mainly has two drawbacks. Firstly, as a common reconstructed model in compressed sensing (CS), L1regularization is a biased estimator [ 14], which means that the amplitude of the targets would be underestimated. Secondly, the support set of the targets is not accurately estimated with the data of one subaperture and there are some missed detections. 
 If they do not agree, the target trajectory prediction is  changed until they do. Thus, the pointing of the antenna is made open-loop based on the  stored target-trajectory prediction updated by the radar measurements. The servo loop that  points the antenna is made relatively wideband (high data rate) to permit a fast tracking  response against targets with high angular acceleration. 
 B. Foote, “Determination of the boundary layer airflow from a single doppler  radar,” J. Atmos. 
  
 Learning Rate When deal with CNNs training, learning rate is an important parameter. Usually, we expected to get the result as soon as possible, so the learning rate we used will be large. However, in common situations, by using large learning rate may cause concussion, and the result may not behave as expected. 
 BEAM CLUTTER  WHICH RAISE THE SYSTEM NOISE FLOOR OR CAN APPEAR AS TARGETS AT THE DETECTORS 4HUS  THE MAXIMUM RATIO OF MAIN 
 The configuration of Fig. 4.9~ is called a double-delay-line canceler, or  simply a do~rhle cartccler. The relative response of the double canceler compared with that of a  single-delay-line canceler is shown in Fig. 
 STEALTH DUE TO UNAVOIDABLE AIRCRAFT RESONANCES IN THE 6(&5(& REGION /THER ATTRACTIVE FEATURES ARE LOWER PRIME POWER REQUIREMENTS AND LOWER COSTS FOR THE 0"2  7HILE A 0"2 CAN EXPLOIT BOTH COOPERATIVE AND NONCOOPERATIVE BROADCAST TRANS 
 Rev., NASA LRC, Nov. 7-8, 1979. 52. 
 ING BY ON AN OTHERWISE 
 LEVEL NOISE DIODE  PREVIOUSLY CALIBRATED AGAINST THE AMBIENT LOAD  MAY BE INJECTED TO MONITOR REAL 
 POL (( AND DUAL 
 BAND RADAR CROSS 
 BEAM AZIMUTH  ON THE TRANSMIT FREQUENCY  AS DESCRIBED IN 3ECTION   THE DOPPLER OF THE MAIN 
 At the upper limit of  spacing. s = /I. tlie iridcx of rcl'riictiori is equal to 0.866. 
 CIENT #Y  APPEARING UNDER THE INTEGRAL SIGN IN THE EXPONENTIAL IN THE BRACKETS  AND BY  EXPANDING THIS EXPONENTIAL IN %Q   IT MAY BE WRITTEN  SY Y           
 \ \   ;     \   =TTKK    AND ITS COVARIANCE   0K    \ K       ;(  
 Dr.Taylor observed that a ship passing between a radio transmitter and receiverreﬂected some of the waves back to the transmitter. In 1930 further tests atthe NRL observed that a plane ﬂying through a beam from a transmittingantenna caused a ﬂuctuation in the signal. The importance of radar for thepurposes of tracking aircraft and ships ﬁnally became recognized when scientists and engineers learned how to use a single antenna for transmittingand receiving. 
 Direct-coupling power isthepower. 410 RFCOMPONENTS [SEC. 11.5 that would becoupled from loop toloop with asolid metal post inthe center ofthe cavity, the annular beyond cutofi. 
 B. Trizna: Mapping of North Atlantic Winds by HF Radar Sea Backscatter Interpretation, IEEE Trans., vol. AP-21, pp. 
 During the interval TN when the returns from transmitted pulse PN are  being received, the two-delay canceler weights should be  A CT T B CN N= = = − −− −1 12 1 (2.40) and the three-delay canceler weights should be  A CT T T B C DN N N= = ++ = − = −− − −1 1 13 1 2  (2.41) These weights have been derived by assuming that the cancelers should perfectly  cancel a linear waveform V(t) = c + at, sampled at the stagger rate, independent of the  values of the constant c or the slope a. (As mentioned at the beginning of this section, a  multiple-delay canceler with binomial weights in an unstaggered system will perfectly  cancel V(t) = c + at.) The choice of A = 1 in both cases is arbitrary. In the three-delay canceler, setting   D = −1 eliminates the opportunity for a second-order correction to cancel the quadratic  term bt2, which could be obtained if D were also time-varying. 
 LEM 7HEN  F TRACK IS LARGE AND VERY LITTLE DELAY IN THE OUTPUT CAN BE TOLERATED  THEN THE  REGION OF APPLICABILITY IS FAIRLY SMALL AND VERY SIMPLE MULTIPLE HYPOTHESIS APPROACHES  SPLITTING TRACKS INTO AT MOST ONE OR TWO HYPOTHESES  ARE THEN THE BEST ANSWER 7HEN FTRACK IS SMALL  THEN 0$!*0$! CAN BE USED TO OPERATE AT SIGNIFICANTLY HIGHER  FALSE ALARM DENSITIES 7HEN SIGNIFICANT DELAY CAN BE TOLERATED IN THE OUTPUT  THEN MANY HYPOTHESES CAN BE FORMED AS IN &IGURE   AND ORDERS OF MAGNITUDE MORE DETECTIONS HANDLED "LACKMAN AND 0OPOLI  PROVIDE A GOOD SURVEY OF COMPARATIVE STUDIES IN THIS  AREA /NE STUDY USING DATA RECORDED FROM FLIGHTS OF CLOSELY SPACED AIRCRAFT SHOWED VERY LITTLE DIFFERENCE BETWEEN '..  *0$!  AND -(4  (OWEVER  THEORETICAL PREDIC 
 Measurements  have shown that the reflection coefficient for normal (nonsmooth) ground terrain is in the  range 0.2 to 0.4 and is seldom greater than 0.5. at frequencies above 1500 MHz except for low  angles of incidence.2g3 ,, 8 &  444INTRODUCTION TORADAR SYSTEMS particular lobewillbedetected atarangetwicethatofthesameradarlocatedinfreespace. However, atotherangles,theradardetection rangecanbelessthanthefree-space range. 
 Abramovich, S. J. Anderson, D. 
 This is the central limit theorem. Another property of the gaussian  distribution is that no matter how large a value x we may choose, there is always some finite  probability of finding a greater value. If the noise at the input of the threshold detector were  truly gaussian, then no matter how high the threshold were set, there would always be a chance  that it would be exceeded by noise and appear as a false alarm. 
 ATED BY THE 53 !IR &ORCE TO DETERMINE THE FEASIBILITY OF USING 8 
 Over  smooth terrain, such as an airport runway, the fixed error might not be averaged out. Note that  cveri if thc fixed error werc not present, the accuracy with which the height can be measured  will deperid on the signal-to-noise ratio, as discussed in Sec. 11.3, and can be comparable to  tlie fixed error as given by Eq.(3.14). 
 EMC, thermal, and vibration tests), which verifies t he systems electrical characte r- istics, as well as its resistance to environmental influences.   SAR Front-End PanelTR Module 1 TR Module 30TR Module  15 TR Module 16 Panel Power Conditioner 2Panel Power Conditioner 1DCM-bustiming cmd + hk Panel Control Electronics A and BTest Interfacetiming timingPCM-bus PCM-bus Power bus Electrical Ground Support Equipment Central ElectronicsDigital Ground Support EquipmentDigital Control Electronics Power Distribution ElectronicsRF Ground Support Equipment Power Feed  Forward, pulse commandsClock, Ext. SyncDESA Master Controller (Command and Control) VME Bus Power Supply (28V)Current and Voltage SensorStatus Monitoring discrete signalsdigital buses (DCM or PCM)power supplies (AC or DC)RF paths timing, commands, housekeepingAC-busStatus signalsto/from RF test facility   Figure 13.28  Block diagram of the phased -array Radar DESA , © Astrium GmbH    . 
 The guide wavelengths ofthe desired and undesired modes aresufficiently different sothat asuitable choice oflength ofround guide will minimize coupling ofthe undesired mode from onerectangular guide totheother. Various absorbers forthe undesired mode aresometimes used. The power-handing abilityofawaveguide, calculated from theelectric fields involved, isapproximately twice that ofthelargest coaxial line that. 
 Peak transmitted power is 500 W, generated from  128 solid-state power amplifiers (SSPAs), one for each waveguide. The 250-m range  resolution is set by the unity time-bandwidth-product 1.6 µsec pulse. The radar has  sufficient sensitivity to respond to rain rates as small as 0.7 mm/hr. 
 -Ê"Ê-"  Ê-// 
 Air Force joined together to install the next generation national network of  WSR-88D doppler radars (commonly called Nexrad radars). Also in the 1990s the FAA  installed the Terminal Doppler Weather Radar (TDWR) system at  major airports in the  U.S. The federal agencies have subsequently implemented many technical upgrades  to the Nexrad and TDWR networks to improve their performance for public warnings  and aviation safety.1,2 In contrast to the WSR-57 and WSR-74C radars they replaced,  the WSR-88D systems provide quantitative and automated real-time information on  storms, precipitation, hurricanes, tornadoes, and a host of other important weather phe - nomena with higher spatial and temporal resolution than ever before.3,4 In the aviation  community, TDWR radars provide crucial information for providing safe departures  and landings at the major airports by detecting hazardous wind shear events such as  microbursts, strong gust fronts, and other performance reducing wind hazards.5,6,7 V arious other types of meteorological radars exist. 
 (collcctioa of 38 rcpricits.)  43. Howard, D. D., J. 
 13.24b best combines simplicity and good characteristics among the negative + +T+ + ti~ ‘$uR, kTj 2E. uR 4 --i ‘-- E. xx ..- E. 
 Range rings may be optionally switched in by the operator to help estimate dis - tances. Precise range measurements are made with the use of a variable range marker   (VRM). At least two VRMs are needed, each with numerical readout in the data area  of the display. 
 Radar—Handbooks, manuals, etc. I. Skolnik, Merrill I. 
 Luncburg. R. K.: "Mathematical Theory or Optics" (mimeographed lecture notes), pp. 
 14 of" Radar Handbook," M. I. Skolnik (ed.), McGraw-Hill Book  Co., New York, 1970. 
 ”Radar works by sending out radio waves from atransmitter powerful enough sothat measurable amounts ofradio energy will bereflected from theobjects to beseenby theradar toaradio receiver usually located, forconvenience, atthesame siteasthetransmitter. The properties ofthereceived echoes areused toform apicture ortodetermine certain properties oftheobjects that cause theechoes. Theradar transmitter may send out c-wsignals, orfrequency-modulated c-w signals, orsignals modulated inother ways. 
 Since the missile responds to a target LOS rate by maneuvering, the missile body orientation with respect to the observed LOS will change as a result of the maneuver. Thus the space-stabilized antenna, while maintaining track of the tar- get, will move with respect to the radome, and the resulting change in the refrac- tion angle will cause an apparent additional LOS rate, closing the feedback loop. The feedback can be either regenerative or degenerative, depending on the sign of the radome error slope (the direction of the radome error).INTERCEPT TARGETMISSILE LINEOFSIGHT OVERSHOOT MISSILE TARGET LINEOFSIGHTMISSILEUNDERSHOOT TARGET LINEOFSIGHT . 
 In many airborne systems, the PRF is chosen to be rather higher than the limit  imposed by the range to the intended target space. In such cases, the extra PRF con - tributes to improved SNR, but at the cost of increased average data rate. Data rate  can be decreased by “pre-summing”—coherently adding n adjacent returns. 
 TIME INFORMATION ON STORMS  PRECIPITATION  HURRICANES  TORNADOES  AND A HOST OF OTHER IMPORTANT WEATHER PHE 
 The useofasawtooth voltage wave fortiming depends upon thefact that thetime taken forsuch awave toreach agiven voltage ispropor- tional tothevoltage chosen. Figure 1336 illustrates acircuit bymeans ofwhich this principle can bevery precisely applied. Tubes Vl,Vl,Vs, and Viconstitute aprecision sawtooth generator. 
 WAVE POWER TRANSISTOR /PTIMIZING THE MOLECULAR CONTENT OF THE &%4 CHANNEL FOR BEST PERFORMANCE IS SOMETIMES REFERRED TO AS  BANDGAP ENGINEERING 4HE  CHALLENGE FOR THE DEVICE ENGINEER IS  TO DEVELOP A TRANSISTOR THAT SUPPORTS THE HIGHEST  VOLTAGECURRENT OPERATION WHILE DEMONSTRATING THE BEST HIGH FREQUENCY GAIN&)'52%  0ERFORMANCE SPACE OF COMMERCIALLY AVAILABLE SILICON POWER TRANSISTORS &)'52%  0ERFORMANCE SPACE OF COMMERCIALLY AVAILABLE SILICON POWER TRANSISTORS . ££°£{  2!$!2 (!.$"//+  4HE COMPLICATION IN POWER TRANSISTOR DESIGN EXTENDS BEYOND THE EXOTIC MATERIAL  FABRICATION TECHNOLOGIES THAT ARE USED TO DEFINE THE BASIC &%4 4AILORED CONSTRUCTION  TECHNIQUES ARE USED TO CONTROL THE ELECTRIC FIELD INTENSITY AND IMPROVE THE BREAKDOWN VOLTAGE ENHANCEMENTS SUCH AS THE FIELD PLATE    DOUBLE GATE RECESS  OR AUTOMATIC  ETCH STOP LAYERS ARE FABRICATION AND DESIGN TECHNIQUES THAT ARE USED TO OPTIMIZE THE  0(%-4 PERFORMANCE FOR A GIVEN OPERATING FREQUENCY RANGE TO BRING HIGHER VALUE  PERFORMANCE  OR RELIABILITY TO THE SEMICONDUCTOR FABRICATION PROCESS 4HE FUNDAMENTAL THREE 
 MENT  IT IS THE FIRST LINE OF DEFENSE AGAINST JAMMING 4HE DIRECTIVITY OF THE ANTENNA IN THE TRANSMISSION AND RECEPTION PHASES ALLOWS SPACE DISCRIMINATION TO BE USED AS AN %##- STRATEGY 4ECHNIQUES FOR SPACE DISCRIMINATION INCLUDE ANTENNA COVERAGE AND  SCAN CONTROL  REDUCTION OF MAIN 
 [ CrossRef ] 2. Toan, T.L.; Beaudoin, A.; Riom, J.; Guyon, D. Relating forest biomass to SAR data. 
 The U.S. Federal Aviation Agency (FAA) uses the following to designate their air- traffic control radars: ● ASR  Airport Surveillance Radar ● ARSR  Air Route Surveillance Radar ● ASDE  Airport Surface Detection Equipment ● TDWR  Terminal Doppler Weather Radar The numeral following the letter designation indicates the particular radar model   (in sequence). Weather radars developed by the U. 
 In one mixer, the IF signal  is beat with the 75 MHz LO with cosine phasing, and in the other mixer, the IF is  beat with the same LO but with negative sine phasing, so that the mixers are operated  in quadrature, 90o apart. The mixer outputs taken together as a complex pair form a  complex signal with the spectrum shown in line 3 of the previous figure. These sig - nals are then passed through lowpass filters (LPF) to remove the spectral component  centered at −150 MHz that would otherwise have resulted in aliasing in the sampling  step to follow. 
 As an  example,40 below 1 mW peak power the output power is linearly related to the input power.  From 10 mW to 100 kW, the output flat-leakage increases by as little as 3 to 10 dB. Below  1-W input power, the diode alone provides the limiting action. 
 ll. M icroware J ., vol. 15. 
 Asradar and target areseparated, keeping h,and h2constant, therange atwhich this inverse eighth-power dependence begins varies asthe reciprocal ofthewavelength; inother words, thelonger thewavelength, thehigher the lowest lobe inFig. 2.11 istilted, and the sooner anout- going target recedes underneath it. This gives aheavy advantage to shorter wavelengths where theprimary task oftheradar setistosearch theseaforlow-lying targets, theradar antenna itself not being mounted atagreat height. 
 BER AND A IS A REPRESENTATIVE OCEAN WAVE AMPLITUDE 4HIS APPROACH  FORMULATED BY  2ICE FOR THE CASE OF A STATIC SURFACE AND EXTENDED BY "ARRICK  TO THE CASE WHERE  THE SURFACE IS EVOLVING ACCORDING TO THE DISPERSION RELATION %Q    LEADS TO AN  EQUATION FOR THE DOPPLER SPECTRUM OF THE REFLECTED RADIOWAVES. 
 A pulse-limited mode of operation is  used in which the intersection of a spherical shell (rep­ resenting the locus of points equidistant from the radar)  with the ocean's surface defines regions where the later­ al extent is small compared to that defined by the an­ tenna beamwidth; i.e., the surface area corresponding  to the range resolution of the altimeter is much smaller  than that encompassed by the antenna beam (Fig. 1).  The earliest signal returns come from wave crests. 
 RESOLUTION FINE RESOLUTION  AND  LOW 
 Non trivial ISAR image reconstruction methods are developed. An accurate method to extract ISAR images of multiple targets by applying Hough transform and particle swarm optimization (PSO) to find residual high order coefficients and to achieve better quality of ISAR imaging and moving target separation is discussed in [ 18]. A method including a genetic algorithm, PSO and PSO with an island model, to compensate for the inter-pulse phase errors caused by the target movement in stepped-frequency ISAR imaging is proposed in [ 19]. 
 Corrections for Atmospheric Refraction.* To further improve the accuracy of height computation, refraction of the radar beam along the ray path to the target must be taken into account. In free space, radio waves travel in straight lines. In the earth's atmosphere, however, electromagnetic waves are generally bent or refracted downward. 
 The bottom row of switches connects the corporate feed to the appropriate elements. The left six elements are active in the configuration illus- trated. When the switches are placed in the alternate configuration, the right six elements are active. 
 CANT DISADVANTAGES  AS WAS DESCRIBED IN THE SECOND EDITION OF THIS  2ADAR (ANDBOOK   THAT MAKE IT LESS LIKELY THEY WILL BE WIDELY USED IN THE FUTURE £ä°xÊ 9,"/," -Î£]ÎÓ]ÎÎ )T HAS BEEN NOTED PREVIOUSLY THAT THE POWER HANDLING CAPABILITY OF THE MICROWAVE POWER TUBES DISCUSSED THUS FAR IN THIS CHAPTER DECREASES AS THE FREQUENCY IS INCREASED 4HIS RESULTS BECAUSE THE RESONANT STRUCTURES OF THE SLOW 
 At more modest distances, the measurement of range can be made with a precision of a few centimeters. The usual radar waveform for determining range is the short pulse. The shorter the pulse, the more precise can be the range measurement. 
 ATED BY THE TRANSMITTER MUST BE KEPT BELOW THE ECHO POWER OF DESIRED TARGETS 4HIS CAN IMPOSE A STRINGENT CONDITION ON THE EMITTED SIGNAL 
 EYE JAMMING   4ERRAIN 
 VIDE  SURVEILLANCE  AND THEY CAN REACH SUCH PERFORMANCE BY MEANS OF SEVERAL DIRECTIVE ANTENNAS 4HE RANGE AT WHICH A RADAR EMISSION IS DETECTED BY AN 272 DEPENDS PRIMARILY ON  THE SENSITIVITY OF THE RECEIVER AND THE RADIATED POWER OF THE VICTIM RADAR 4HE CALCU 
 . www.tektronix.com/radar  9    Figure 10. RF pulse spectrum (top) an d pulse trace (bottom)   Transmitter Tests   Modern radars often generate pulses at an Intermediate  Frequency (IF) where the processing is easier and then  convert the IF  frequency to the final CW frequency before  amplifying it to the necessary high power. 
 FEED NETWORKS .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°{ BALANCED COMPONENTS ARE RETURNED TO THE INPUT 4O BREAK UP PERIODICITY AND REDUCE  PEAK QUANTIZATION LOBES 3ECTION    SMALL ADDITIONAL FIXED PHASE SHIFTS MAY BE INTRODUCED IN THE INDIVIDUAL LINES AND COMPENSATED BY CORRESPONDING READJUSTMENTS OF THE PHASE SHIFTERS 4HE REACTIVE FEED NETWORK SHOWN IN &IGURE  B IS SIMPLER THAN THE MATCHED  CONFIGURATION )T HAS THE DISADVANTAGE OF NOT TERMINATING UNBALANCED REFLECTIONS THAT ARE LIKELY TO BE AT LEAST PARTLY RERADIATED AND THUS CONTRIBUTE TO THE SIDELOBES ! STRIPLINE POWER DIVIDER IS SHOWN IN &IGURE C  AND A CONSTRAINED OPTICAL POWER DIVIDER USING AN ELECTROMAGNETIC LENS IS SHOWN IN &IGURE  D 4HE LENS MAY BE OMITTED AND THE  CORRECTION APPLIED AT THE PHASE SHIFTERS 7ITH NONRECIPROCAL PHASE SHIFTERS  A FRACTION OF THE POWER REFLECTED FROM THE APERTURE WILL THEN BE RERADIATED AS SIDELOBES  RATHER THAN RETURNED TO THE INPUT 4HE AMPLITUDE DISTRIBUTION ACROSS THE HORN IS GIVEN BY THE WAVEGUIDE MODE )T IS CONSTANT WITH AN % 
 The factor appears before the integral  because the limits extend from - oo to + oo, whereas No is defined as the noise power per cycle  of bandwidth over positive values only. Substituting Eqs. (10.8) and (10.9) into (10.7) and  assuming that the maximum value of Is,(t)12 occurs at time t = tl, the ratio Rf becomes  Schwartz's inequality states that if P and Q are two complex functions, then  The equality sign applies when P = kQ, where k is a constant. 
 The ‘sensitivity ’of the radar on each trial was determined from the detection range of Grassholm Island (see ﬁgure 4.32). The mean sensitivities were 23.5 nmi for ASV Mk. III and 38.5 nmi for ASV Mk. 
 D. E. Barrick, W. 
 W.: Moving Target [ndication Radar, IEEE 74 Record NEREM, Pt 4, pp. 18-26.  Oct. 
 Because ofthese variations ofcross section, ithas been necessary to modify the definition ofcross section, inorder tomake atleast the experimental definition unique. 40db I’1[:.39.-Return power from anAT-I 1aircraft at10-cm wavelength asafunction of azimuth angle, InRLReport A’o. 64-10,1 where anumber ofmeasured cross sections aretabulated, the convention ismade that the cross section attains the tabulated value during one half ofaseries oftime intervals. 
 242–246, 1960. 58. P. 
 Eventually, polarization diversity techniques may improve quantitative hail detection. Aydin, Seliga, and Balaji71 propose a hail-detection technique using reflectivity measurements at orthogonal polarizations. This technique depends upon the fact that the ratio of horizontal to vertical reflectivity is unity («0 dB) when hail is present. 
  D" ! CLEAR 3!2 IMAGE MUST HAVE AN 3.2 GREATER THAN ABOUT  D" &ROM "ARTON AND  SUMMARIZED IN 3ECTION  OF 3ULLIVAN  WE SEE THAT THIS EXAMPLE 3!2 COULD IMAGE  hWOODED HILLS v IE   R   y  
 Radarantennas arecharacterized bydirective beamswhicharescanned, usuallyrapidly. Theparabolic reflector, wellknowninoptics,hasbeenextensively employed inradar.Thevast majority ofradarantennas usetheparabolic reflector inoneformoranother. Microwave lenseshavealsofoundsomeradarapplication, ashavemechanically rotatedarrayantennas. 
 RANGE PERFORMANCE AND BY HAVING A DIS 
 Austin, P. M.: Radar Measurements of the Distribution of Precipitation in New England Storms,  Proc. 10th Weather Radar Conj., pp. 
 122] ATYPICAL RECEIVING SYSTEM 435 a.True plots ofaplane surface inwhich range and anangle are combined aspolar coordinates (PPI). b.Rectangular plots oftwo cartesian components ofrange, in general with unequal normalizations’ (stretched PPI, RHI). c.Rectangular plots ofthe polar coordinates, range and angle (B-scope, E-scope.) d.Rectangular plots ofazimuth angle and elevation angle (type C). 
 Lyon, I. D.: Scan-Converted Bright Displays for Air Traffic Control Systems, Conference on Air  Traffic Control Systems E11gi11eering and Design, London, Mar. 13-17, 1967. 
 The e ﬀectiveness of the proposed method is veriﬁed by both simulated data and the real TerraSAR-X image data compared with the signal spectrum weighting algorithms. This letter describes a method for azimuth sidelobes suppression using MPS SAR data. In Section 2, the imaging geometry is introduced. 
             (a)  
 117. Hlevis. R. 
 Section 4presents the experimental results. The conclusions are presented in Section 5. 2. 
 4, pp. 563-571, 1987. 82. 
 SPEED CRAFT  THE ROTATION RATE IS TYPICALLY n RPM &OR 3/,!3 VESSELS  THE ANTENNA MUST BE ABL E TO START AND OPERATE IN  RELATIVE WIND SPEEDS UP TO  KT OTHER ENVIRONMENTAL REQUIREMENTS FOR THE ANTENNA SYSTEM ARE DETAILED IN )%#    WHERE THERE ARE SPECIFIC TESTS FOR hEXPOSEDv EQUIPMENT 4HERE ARE NO EXPLICIT REQUIREMENTS ON OTHER ANTENNA PARAMETERS FOR 3/,!3 
 Several methods ofsupporting thecrystal from therear while retaining themercury asa backing medium have been tried. Amore promising approach tothe design ofanabsorbing end cell istheuseoflead soldered tothe quartz. The lead provides agood acoustic match tomercury, while strongly attenuating thesupersonic energy that itreceives. 
 Iftheuppcrthreshold isexceeded, thesignalisdeclared tobepresent alongwiththenoise.Butiftheoutputliesbetween thetwothresholds, nodecision ispossible anllanolherohservationisIll<lde. ThcSequcntial Observer permitsasignificant reduction intheaveragenumberofsamples (pulses) neededformakingadecision. Theimprovement depends uponwhether asignalis presentornot.Ifasignalispresent, theaveragenumberofsamples (orobservations) required formakingadecision issignificantly greaterthanwhennoisealoneispresent.TheSequential Observer makesarelatively promptdecision whenonlynoiseispresent. 
 Modern radar would be  much less interesting or useful if the doppler effect didn’t exist. The doppler frequency  shift fd can be written as  f v vd r= =2 2/ ( cos ) / λ θ λ (1.1) where vr = v cos q  is the relative velocity of the target (relative to the radar) in m/s, v is   the absolute velocity of the target in m/s, l is the radar wavelength in m, and q is the  angle between the target’s direction and the radar beam. To an accuracy of about 3 per - cent, the doppler frequency in hertz is approximately equal to vr (kt) divided by l (m). 
 We use the 3 ×3 ﬁlter window for phase ﬁltering, thus NL=9. According to Equation (32) and Figure 12, the h–σpscurve can be acquired, as shown in Figure 13. Figure 13. 
 Low-Noise Amplfiiers.  (1) Multiple stage linear designs require proper device  sizing of successive stages in order to maintain low intermodulation distortion  products. (2) Circuit losses on the input, before the first stage, degrade the noise  figure of the design; therefore, some designs utilize off-chip matching. 
 may be considered as a broadband directional coupler with a coupling ratio of 3 dB. In the  transmit condition (Fig. 9.6a) power is divided equally into each waveguide by the first short­ slot hybrid junction. 
 III transmitter receiver type 3090. The Lucero equipment is described further in chapter 6. A simpli ﬁed block diagram of the radar is shown in ﬁgure 3.2. 
 Doppler logs do not always give good speed readings on some types of  seabed, for example, soft mud. Facilities must also be provided to allow the use of  stationary tracked targets, such as radar conspicuous navigation marks, to provide  the ground reference. According to the design, the basic tracking function can be carried out in ship or  ground/sea referenced frames, using conventional algorithms. 
 Tosimplify thetuningofaklystron itisdesirable tohavea"gangtuner"bywhichallthe cavitiesarecontrolled byasingleknobwhen changing frequency. Gangtuningiscomplicated, however, sincetheresonant cavitiesdonotgenerally havethesametuningrates.Thechannel tllningmechanism avoidstheproblem ofthefrequency tracking oftheresonant cavities by pretuning thecavities(generally atthefactory); andthetuninginformation isstoredmechan­ icallywithinthetunermechanism. Thuswhenaparticular frequency channel isdesired, the tunermechanism provides thecorrecttunerposition foreachcavitytoachievethedesired klystron frequency response. 
 The ships and the wakes produced by the ship motion were imaged. The ship image  (a blob) appeared displaced from its wake due to the doppler shift caused by the ship’s  motion relative to the spacecraft. However, the ship’s position at the time of imaging  and its course could be determined from the wake. 
 They do not  have, in general, sufficient stability to permit large values of k. When analog lines are used,  loop gains $re not much larger than 0.9 in the configuration of Fig. 10.10a, and 0.98 in the  configuration of Fig. 
 TRANSMITTED COMMAND SIGNALS FIRST  SCATTERED OFF THE PLANETS SURFACE AND CHARACTERIZED BY THE RECEIVER 
 OFF WITH THE COMPUTATIONAL COST 4O REDUCE THE COMPUTATIONAL LOAD  DIFFERENT COMPUTATIONAL STRATEGIES MAY BE DEVISED  FOR EXAMPLE  BY CALCULATING THE ADAPTED TWO 
 HOLD CIRCUIT REMOVES THE TRANSIENTS DUE TO THE NONZERO TRANSITION TIME OF THE DIGITAL 
 The first term represents  the no-error power pattern multiplied by the square of the fraction of elements remaining and  by a factor proportional to the phase error.' The other term depends on both the amplitude  error and the phase error as well as the fraction of elements remaining operative. It also  depends on the aperture illumination, as given by the currents imn. Note that this second term  is independent of the angular coordinates 8, cf,. 
 The PPI does not have a resolution that approaches the resolution of the signal-processing . REFLECTIVITY cr ° (dB) FIG. 15.10 Distribution of reflectivity for ground clutter typical of heavy clutter at S band. 
 The value of  these lobes may be estimated from the various results shown in Figure 13.21 or actu - ally computed by summing all contributions at the known quantization (grating) lobe  angles. The distribution becomes smoother as the number of subarrays is increased or  as they are interlaced. 13.7 BANDWIDTH OF PHASED ARRAYS The phenomenon of focusing an array is the result of the energy from each element  adding in-phase at some desired point within the antenna. 
 8.1 Collapsing loss versus collapsing ratio for a probability of false alarm of 10~6 and a probability of detection of 0.5. (Copyright 1972, IEEE; from Ref. 5.) S/N (dB) FIG. 
 The received energy is an extremely small part of t he  transmitted energy. How small is it?   22 3 44t rx tx sGPP RL     The radar equation relates the important parameters affecting the received signal of radar. The  derivation is explained in many texts1. 
 The ducts which wehave described have nogreat vertical extent, their heights being ofthe order ofafew tens, oratthe most afew hundreds, offeet; their influence onpropagation isusually confined tofrequencies inthe 1000-M c/sec range and above.’ For gradients inrefractive index which would not beunusual inthese surface ducts over water, the relation between height ofduct and thelongest wavelength strongly affected by theduct issuggested bythefigures inTable 2.3. TABLE 2.3 Height totopof duct, ft................ 25 50 100 200 4@3 Longest wavelength trapped, cm*. 
 SIZE DISTRIBUTION ON THE ATTENUATION RATE (E ALSO REVIEWS MORE RECENT EMPIRICAL DATA 4HE GREATEST UNCERTAINTY IN PREDICTION OF ATTENUATION RATES CAUSED BY RAINFALL   WHEN THEORETICAL FORMULAS ARE USED AS A BASIS FOR CALCULATION   IS THE EXTREMELY LIM 
 The results will not be greatly dependent upon the  particular values of susceptance and conductance chosen. Similarly, the variation of the ob­ served quantities can be studied as a function of the load presented to the magnetron, with the  input parameters-magnetic field and current-likewise chosen for convenience. The plot of  the observed magnetron quantities as a function of the input circuit parameters,,for some fixed  load, is called the performance chart. 
 2.43  Elevation-Angle Interference-Region  Calculation  ......................................................  2.43  Refraction and Coverage Diagrams  ...................  2.44 . 
 Ê  1// 
 73.Hsiao,J.K.:Analysis ofaDualFrequency Moving TargetIndication System,TheRadioufldElec­ CronicEngineer, vol.45,pp.351-356,July,1975. 74.Andrews, G.A.:RadarAntenna PatternDesignforPlatform MotionCompensation, IEEETrailS., vol.AP-26,pp.566-571, July,1978. 75.Hadjifotiou, A.:Round-off ErrorAnalysis inDigitalMTIProcessors forRadar,TheRadioand Electronic Engineer, vol.47,pp.59-65,January/February, 1977. 
 POLAR COMPONENT )N PRACTICE  IT HAS BEEN FOUND THAT EXCELLENT ICE DETECTION CAN BE MADE BY OPTIMIZED  PROCESSING OF CONVENTIONAL MARINE RADAR SIGNALS  "ECAUSE OF THE SLOW 
 WAVE 474 
 The antenna-synthesis technique based on sampled values was introduced by Levin-  son at the MIT Radiation Laboratory in the early forties and was apparently developed  independently by Woodward in England.7.77-79  The classical sampling theorem of information theory states: If a function f (t) contains no  frequencies higher than W Hz, it is completely determined by giving its ordinates at a series of  points spaced 112 W seconds apart. The analogous sampling process applied to an antenna  pattern is that the radiation pattern E,(4) from an antenna with a finite aperture d is com-  pletely determined by a series of values spaced L/d radians apart, that is, by the sample values  E,(itA/d), where ti is an integer.73 In Fig. 7.23~ is shown the pattern E(4) and the sampled  points spaced A/d radians apart. 
 14 step inoutput power was due toanimprovement inthemagnetron itself. The increase at10-cm wavelength intheearly part of1941 was brought about bythedevelopment ofmodulators ofhigher power. Itisimportant torealize that the curves ofFig. 
 (ALL     3 $ #AMPBELL AND 3 ( /LSON  h2ECOGNIZING LOW 
 Experiments have shown that higher field  strengths are generated at over-the-horizon ranges when the transmitting antenna  is located close to sea level, rather than in an elevated position; placing the antenna  even just one or two wavelengths above sea level can introduce several dB of  additional loss.156 • Most HFSWR systems use a very broad “floodlight” transmit beam to illuminate the  entire coverage arc; multiple simultaneous receive beams are formed to fill the arc  and update all tracks simultaneously. This reduces cost and complexity but incurs  some loss of sensitivity for noise-limited target detection. • Coherent integration times may extend to hundreds of seconds, as HFSWR is not  reliant on the ionosphere as a medium for propagation. 
 The imagesobtained withconventional noncoherent radararegenerally different thanthoseof coherent SARinthattheyarelessspeckled. InverseSAR.Insteadofmoving aradarrelative toastationary object,itispossible to generate animagebymovingtheobjectrelativetoastationary radar.Imaging withastation­ aryradarandmovingtargetiscalledinverseSARorrange-doppler imaging.Ithasbeenapplied. OTHER RADAR TOPICS 529  Figure 14.7 1 nverse SA R, or range-doppler imaging,  of a rotating object. 
 Table 8.2 is an example of  a priority structure for a tactical air defense system in which the radar performs search  and automatic tracking, as well as support missile engagements.12' There are eight categories  of priority, from the dedicated mode with the highest priority, to the standard testing and  dummy operations (or time wasters) with the lowest priority. There is more than one  similar function within each category which can be treated either on a first-in--first-out  basis or by giving further priority ordering. Note that the subcategories of the "0" priority  also appear in lower-priority categories. 
 626-638, September 1980. 22. Lain, C. 
 17.3] SCANNER-DA TA TRANSMISSION 683 variety. Complications introduced bymultiple sets will bedescribed later. 17.3. 
 60 HOW RADAR WORKS  At the foot of the tube is the cathode or filament,  glowing and releasing electrons, negative electrical  charges, just as does the filament of a radio valve. These  released electrons can be attracted if a neighbouring  plate or cylinder is given a positive charge, or they can  be repelled back into the cathode if the plate is given a  stronger negative charge. Alternatively the cylinder  may be placed end-on to the cathode and given such  a strong positive potential that the electrons released  from the cathode form a beam and are attracted away  at such a high velocity that they do not stop at the  positively charged cylinder, but continue on. 
 CENTERED%QS  TO  IN #ARTESIAN %ARTH 
 E. Daniell, Jr. and D. 
 Pulsed doppler systems are far more prevalent than CW radars.  Primarily, center-fed parabolic dish antennas with focal-point feed and low-noise  solid-state digital receivers are used. Magnetrons, klystrons, traveling-wave tubes, and  other forms of transmitter forms are routinely used. 
 Of the nuclear power systems that were placed into orbit between 1961 and 1977, only one was a nuclear reactor, SNAP-IOA. Since then the tech- nology has advanced58"61 to the extent that it is estimated that an SP-IOO type of nuclear reactor would have a mass of 2770 kg and a power output of 100 kW, thereby providing a specific power density of 36 W/kg. Two baseline deployment configurations of solar-battery and nuclear prime power systems were designed with two power levels, 25 and 100 kW, for the same deployment altitude and are shown in Fig. 
  
 The following two papers [ 15,16] concern this kind of applications. The work in [ 15] proposes the use of aspect entropy for quantifying the degree of anisotropy in SAR backscattering, and thus improving the detection of anisotropic targets and their classiﬁcation. The proposed method applies to SAR systems acquiring under di ﬀerent look angles, as circular SAR. 
 14Antenna Parameters • Gain is the radiation intensity relative to a lossless isotropic reference. • Fundamental equation for gain: • In general, an increase in gain is accompanied by a decrease in  beamwidth, and is achieved by in creasing the antenna size relative  to the wavelength. • With regard to radar, high gain and narrow beams are desirable for  long detection and tracking ranges and accurate direction measurement.24/ , effective area   = aperture area  efficiency (0 1) /,  w a v e l e n g t he eGA AA A cfπλε εελ= = =≤ ≤ =Low gain                   High gain (Small in wavelengths)       (Large in wavelengths) ANTENNA DIRECTIONAL   RADIATION PATTERNAperture area. 
 the reference signal is  Vrer = A1 sin 2rr.f;r  and the doppler-shifted echo-signal voltage is  V . [2 ( r f') 4rrf;R0] echo= A3 Sill 7t .Ir±. d ( --~--- where A1 = amplitude of reference signal  A 3 = amplitude of signal received from a target at a range R0  .f.i = doppler frequency shift  t = time  c = velocity of propagation (4. 
 Rao, and N. Rajeevjyothi, “SAR payload of  radar imaging satellite RISAT) of ISRO,” in Proceedings , 6th European Conference on Synthetic  Aperture Radar , Dresden, Germany, VDE Verlag, 2006. 28. 
 34!4% 42!.3-)44%23   ££°ÓÇ 4RANSMIT2ECEIVE  3WITCHING    &OR SWITCHING APPLICATIONS  THE &%4 DESIGN  SHOULD BE CHOSEN SUCH THAT THE RATIO OF /&& 
 1022–1031, June 2002. 23. R. 
          [í 6XEDSHUWXUHLQGH[5HVSRQVHPDJQLWXGH%3 &6 'HEDLVHGí &6 /6í&6í5HVLGXDO Figure 5. Reconstructed aspect dependent scattering of target via the three methods. 36. 
 There have been at least two different variations of within-pulse scanning which have . TIIF. l'f.f:CTRONICALI.Y STEERED PHASED ARRAY ANTENNA IN RADAR 315  heen demonstrated experimentally. 
 In the iteration, the value of λis λ=|ˆβt i|K+1/μ, (16) where|ˆβt i|K+1is the (K+1)-th largest element ofˆβt iand K=/bardblˆβt i/bardbl0. The ﬁnal estimation is ˆsi=βi+si,init. (17) 31. 
 Sensors 2019 ,19, 1649 Figure 12. B-SAR focusing. Caramanico site, Fucino Valley, Italy. 
 The output ofthe beacon crystal, which iscoupled tothe local oscillator through the reference cavity, is amplified inV6and then applied toVT. Asexplained inSec. 12.7, thephase ofthe a-famplitude modulation ofthe signal from the beacon crystal will change by180° when the fre- quency ofthelocal oscillator crosses thecenter frequency ofthereference. 
 18.50  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 from an elliptical orbit was of little concern to the budget-masters, although the ellip - tical orbit constraint attracted more than a little attention from the SAR design team.  The Magellan  radar had to adapt to variations in relative altitude from approximately  250 km (near the equator) to more than 2000 km (over the poles). Quite reasonably  one might expect that the resulting imagery—let alone the implied timing and scal - ing issues—would suffer as a consequence. 
 B.: Advances in the Design of Foster Scanners, RADAR-77, Oct. 25-28, 1977, London,  IEE Conference Publication no. 105, pp. 
 BAND SIGNAL  n D"I THREAT SIDELOBE   AND n D"7 THREAT SENSITIVITY  A JAMMING PULSE  D" ABOVE MINIMUM SENSITIVITY CAN BE GENERATED AT  KM /BVIOUSLY  IN THE NEAR SIDELOBES OR MAIN BEAM  THE RANGE FOR A  D" PULSE WILL BE MUCH GREATER  x°{Ê -Ê " 
 AXIS 4HE IMAGE CENTER IS A DISTANCE  3   2G COS PSQ FROM  THE X 
 2'0/ ! 
 TIONS SEE 3ECTION  OF 7IRTH  4HE SUPERRESOLUTION CONCEPT WAS MAINLY DEVELOPED AND ANALYZED BY 7 & 'ABRIEL  AT THE .AVAL 2ESEARCH ,ABORATORY 53  $IFFERENT METHODS FOR BEARING ESTIMATION WERE DESCRIBED BY 'ABRIEL AND  SUBSEQUENTLY  BY OTHER AUTHORS  n /NE IS THE MAXI 
 NOISE RATIO REQUIRED TO DETECT TARGETS &IGURE  ILLUSTRATES THIS OPTIMIZATION FOR AN EIGHT 
 Spurious signals can also arise during the flat part of the pulse. The greater the RF  drive the less will be the in-band noise. Thus the lower the gain the less will be the noise. 
 Because of thefrequenciesandpoweroutputsrequired,thetransmitteroscillatorisaspecialtype known as a MAGNETRON.Transmitting and Receiving Antenna System The function of the antenna system is to take the r-f energy from the transmitter, radiate this energy in a highly directional beam, receive anyechoes or reﬂections of transmitted pulses from targets, and pass theseechoes to the receiver. In carrying out this function the r-f pulses generated in the transmitter are conductedtoaFEEDHORNatthefocalpointofadirectionalreﬂector,fromwhich the energy is radiated in a highly directional pattern. The transmittedand reﬂected energy (returned by the same dual purpose reﬂector) areconducted by a common path. 
 The carriage hasanoptical system which projects asmall spot oflight upthrough theglass surface oftheplotting board. Over the surface oftheplotting board isstretched amap ofthe area surrounding theradar set, carefully adjusted sothat thepoint onthemap occupied by theradar isdirectly above thepivot ofthemoving arm. The scale factor oftherange-carriage mechanism isadjusted tocorrespond \vith thescale ofthe map being used, which may beeither 1to50,000 or1to100,000. 
 184 lNTHODUCTlON TO RADAR SYSTEMS  of pulses expected to be returned from a target as tile at~tcnna scatis past. The integrated pulscs  are compared with a threshold to indicate the presence or absence of a target. An example 1s  the commonly used moving window detector which examines continuously the last r15amples -  within each quantized range interval and announces the presence of a target if m out of 11 of  these samples cross a preset threshold. 
 F., and T. B. A. 
 Anderson, M. W. Fox, P. 
 Measurements ofangle can bemade by means ofsimilar electronic indices, but fixed lines etched onatransparent overlay plus, perhaps, amovable mechanical cursor, areoften used. 12.2. ATypical Receiving System.—Figure 12.1 illustrates the principal parts and some ofthesubdivisions ofatypical receiving system containing acathode-ray-tube indicator. 
  +1 
 , (N - I)$. If the beam is scanned as a function of time. these phase  stlifts also change as a function of time. 
 bicolor penetration·CRT, for example, might employ a layer of  red phosphor and a layer of green separated by a layer of transparent dielectric material.26•2 7  At low anode voltage (6 kV) the red phosphor is excited. At high voltage (12 kV), the  green phosphor is excited. With intermediate voltages, yellow and orange can be obtained,  giving a total of four different colors which can be distinguished. 
 18.2 Angle error sensing in one coordinate by switching the antenna beam position from one side of the target to the other, (a) Target located on the antenna axis, (b) Target at one side of the an- tenna axis. error) independent of the amplitude of the echo signal. This provides the constant gain in the angle-tracking loops necessary for stable angle tracking. 
 It is also possible to give identical phase-steering commands to similar  elements in each subarray, thus allowing simplification of the beam-steering unit and of the  interface cabling between the array and the beam-steering unit. The term subarray has also  been applied to the array feed networks for producing sum and difference radiation patterns.82 . 310 INTRODUCTION TO RADAR SYSTEMS  Pickup horns ·· ·  Pillbox  used  OS  array , ,  feed  L_ ...... 
 The drift angle is the angle between the horizontal projection of  the centerline of the aircraft (heading) and the horizontal component of the aircraft velocity  vector (ground track). From the ground-speed and drift-angle measurements, the aircraft's  present position can be computed by dead reckoning.  An aircraft with a doppler radar whose antenna beam is directed at an angle )' to the  horizontal (Fig. 
 £Î°x{  2!$!2 (!.$"//+  4HE RECEIVER REQUIRES AN EARLY GAIN OF TYPICALLY  TO  D" TO ADEQUATELY ESTABLISH  A LOW NOISE FIGURE AND ALLOW FOR PHASE SHIFTING AND BEAMFORMING LOSSES 4HE MODULE  ALSO RECEIVES INTERFERING SIGNALS FROM ALL DIRECTIONS WITHIN THE ELEMENT PATTERN NOT SIMPLY THE ANTENNA PATTERN   AT ALL FREQUENCIES IN THE BAND 4IGHT TOLERANCES BETWEEN MODULES ARE NEEDED TO PROVIDE AMPLITUDE AND PHASE TRACKING OVER THE BAND FOR LOW 
 3CALE -ODELS  2ECOGNITION THAT EXISTING MODELS  WERE INADEQUATE FOR DESCRIBING OCEAN SCATTER LED TO RECOGNITION THAT RESONANCE OF THE  SIGNAL WITH SMALL STRUCTURES ON THE SURFACE HAS A POWERFUL INFLUENCE ON THE STRENGTH OF THE SIGNAL RECEIVED   4HUS A SMALL 
 801–804,  1978. 109. J. 
 However, it is worthwhile noting these general rules: (1) Confirmation dwells  should have a priority higher than all other functions except those associated with weapon   control; (2) low priority tracks (e.g., tracks at long range) can be updated using search  detections; and (3) high priority tracks should have a priority higher than volume surveil - lance. The update rate for high priority tracks should be such that a single tracking dwell is  sufficient to update the track. The actual update rate will depend on many factors includ - ing (a) maximum target speed and maneuver capability, (b) radar beamwidth (beam could  be spoiled), (c) range of the radar track, and (d) accuracy of predicted position. 
  
 OF 
 One such propagation model, the Advanced Propagation  Model (APM) and its graphical user interface program, the Advanced Refractive  Effects Prediction System (AREPS),1 are featured here. While the focus upon AREPS  within this chapter is for the understanding of how important the propagation factor is  within the radar equation, AREPS is much more than a propagation factor tool. AREPS  provides the radar engineer and the operational radar operator with an easy to use but  extremely powerful method to define the natural atmospheric environment using data  from a wide range of sources; to manage, create, and define various elements of ter - rain data; to execute the appropriate propagation model for the task at hand; and then  to present the results in a number of different and highly configurable graphic and Chapter 26 ch26.indd   1 12/15/07   4:52:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 LITE COMMUNICATIONS  MICROWAVE LINKS  FIBER OPTICS  AND OTHER MEDIA .EVERTHELESS  THE INCREASED NUMBER OF (& RADARS HAS LED TO A NEW CHALLENGE INTER 
 BEAM CLUTTER PERMITS AS WIDE OF A CLUTTER REJECTION NOTCH AS REQUIRED TO REJECT MAIN 
 The  detection range of CW radar  systems is relatively short, due to  the constraint s of continuous RF power . There is no minimum  range, however,  which makes CW radar particularly useful for  close -in applications.   Pulsed Radar   The r adar measurements discussed in this document  are all  pulse measurements. 
 A separate solid-state source  can be used at each element of the antenna, or a number of sources can be combined to feed  each row (or each column) as in the AN/TPS-59, Fig. 6.15.~' The mechanically rotating array  antenna with solid-state transmitters has some special problems of its own that must be  overcome. One such problem is the need to convey large power to the solid-state devices on  the rotating antenna. 
 LAYER SAND 
 Henderson and A. J. Lewis (eds.), Principles and Applications of Imaging Radar ,   New York: J. 
 Using GNSS signals as a proxy for SAR signals: Correcting ionospheric defocusing. Radio Sci. 2016 ,51, 60–70. 
 The result of RCS curve denoising is shown in Figure 6d. Figure 7shows the comparison of the percentage error for aspect entropy calculation in different SNR between with and without denoising. It can be found that the denoising method signiﬁcantly improved the accuracy of aspect entropy in low SNR. 
 -ISSION 2ADAR  4HE -ULTI 
 CALLED  PULSE 
 . DETECTOR  WILL REJECT THE RESIDUE AND KEEP THE TARGET AFTER 4 - (ALL AND 7 7 3HRADER  Ú )%%%  
 Independence ofInterrogation and Reply .—Although thefunda- mental considerations that underlie the design ofbeacons and beacon systems arethesame asthose forradar ingeneral, there arecertain con- sequences ofthealmost complete independence oftheinterrogation and reply links that need explicit mention. Range.—The expression forthepower received bythebeacon isgiven byEq. (2.14). 
 TIONAL AIDS SUCH AS ELECTRONIC CHARTS AND INTEGRATED NAVIGATION SYSTEMS 4HE RELIANCE OF NAVIGATION ON A SINGLE SYSTEM  SUCH AS '03  OR  EVEN A SINGLE TECH 
 Mahafza, Radar Systems Analysis and Design using MATLAB, 2000 , Boca Raton: Chapman  & Hall/CRC, 2000. 43. B. 
 WORLD PROPAGATION 4HE MOST  SIGNIFICANT PRACTICAL EXPLOITATION OF SUCH PHENOMENA CAN BE FOUND IN EXPERIMENTS DIRECTED AT IONOSPHERIC MODIFICATION Óä°xÊ 76 
 The signal from the previous  transmission, which is delayed by a time T = pulse repetition interval, is  V2 = k sin [2nfd(t -T) -<Po] (4.5)  Everything else is assumed to remain essentially constant over the interval Tso that k is the  same for both pulses. The output from the subtractor is  V = V1 -Vi = 2k sin nf4 T cos [2nf4( t -~) -<Po] (4.6)  It is assumed that the gain through the delay-line canceler is unity. The output from the  canceler [Eq. 
 D. A. Shnidman, “Radar detection probabilities and their calculation,” IEEE Transactions on  Aerospace and Electronic Systems , vol. 
 The re- radiation characteristics are represented in Figure 11.14.  Representative is the distinct  broad maximum.  This is clearly obvious in the three -dimensional r epresentation. 
 296 INTRODUCTION TO RADAR SYSTEMS  Waveguide. Matching  transformer Nonreciprocal Phase element with-7  polarizers coil and yokes 1  ) Output Figure 8.13 Oual-modl! rl!Cl­ procal phase shifter configura­ l ion. ( From W hick a a11d  }' 01111/). 
 J. Elkins, “A model for high frequency radar auroral clutter,” RADC Rept. TR -80-122,  March 1980. 
 R., and J. G. Schoenenberger: Totally Independent Bistatic Radar Receiver with Real-Time Microprocessor Scan Correction, IEEE Int. 
 529–543, 1987. 168. S. 
 Summary of SAR Resolution.  We have, therefore, now derived the two basic  formulas for SAR resolution:  δ δλrc B= =/2 2RangeResolutio n cr∆q q≈λR L2SACrossrangeResolutio n (17.9) The processing described produces a two-dimensional array of complex numbers,  i.e., each consists of a magnitude and a phase. This ordered array of complex numbers  as a function of downrange and crossrange produces a complex radar image, i.e., each  pixel consists of a magnitude and a phase. 
 ONLY CONICAL 
 Turriti: Depolarization Properties of Offset Reflector Antennas. IEEE Tratts.,  vol. AP-21. 
 In 1903 a German engineer by the name of Hiilsmeyer experimented with the detection of  radio waves reflected from ships. He obtained a patent in 1904 in several countries for an  obstacle detector and ship navigational de~ice.~ His methods were demonstrated before the  German Navy, but generated little interest. The state of technology at that time was not  sufficiently adequate to obtain ranges of more than about a mile, and his detection technique  was dismissed on the grounds that it was little better than a visual observer. 
 MATION OF POLARIZATION STATE UPON REFLECTION  AS WELL AS THE MAGNITUDE AND PHASE OF EACH REFLECTION COEFFICIENT )T IS OFTEN TRUE THAT THE FIELD POLARIZATIONS ARE NOT CHANGED DURING PROPAGATION  THE IRROTATIONAL ASSUMPTION )N THIS CASE  THE POLARIZATIONS OF THE BACKSCATTERED WAVES ARE EQUIVALENT TO THOSE THAT ARRIVE AT THE RADAR 4HIS PROPERTY CHARACTERIZES MOST OF THE POLARIMETRY LITERATURE  AT LEAST IN REMOTE SENSING APPLICATIONS  AND IS REFLECTED IN THESE PARAGRAPHS 4HE PRINCIPAL EXCEPTION TO THIS RULE IS &ARADAY ROTATION  WHICH MAY BE A SIGNIFICANT FACTOR FOR LONGER WAVELENGTH SYSTEMS  SUCH AS 0 BAND AND TO A LESSER EXTENT , BAND  &OR IRROTATIONAL PROPAGATION  THE PORTION OF THE BACKSCATTERED FIELD CAPTURED BY THE  RADAR IS DETERMINED BY THE POLARIZATION VECTOR OF THE RECEIVING ANTENNA  ; %  2= 4HE SIG 
 radar.orapulse-compression radarcanprovide sufficient range-resolution toobtainaprofileofthetargetshape,asdetermined bythetarget's. liX I IIA['I ION 01. 1NI:ORMATION AND WAVEFORM DESIGN 435  major scattering centers. 
 Figure 12shows the aspect entropy images of the four targets. The results indicate that 0.91 is a suitable threshold value. Figure 13shows the binary images of the four targets. 
 41-53,  June, 1957.  69. Cooper, D. 
 VIEWING ALTIMETER TO THE %ARTH BY A VERY SMALL FRACTION OF THE SPEED OF LIGHT  BUT SUFFICIENT NEV 
 4  CONTRACT !&  
 Jones, and E. C. Poggio, “Development in radar  imaging,” IEEE Trans ., vol. 
 Gross: Beam Shape Loss and Surveillance Optimization for Pencil Beam  Arrays, IEEE Trans., vol. AES-5, pp. 674-675, July, 1969. 
 Whenthe hackground noiseislowandforshort-pulse modulation thelaserenvelope detector can operateasaquantum-limited deviceandgiveessentially thesamedetectil'ity (inverseofthe noiseequivalent power)asheterodyne detectors.8s(Thisisunlikemicrowaves wherethevideo detector isfarlesssensitive.) Theheterodyne, orphotomixing, receivercanhaveanarrow passband andsignificantly reducetheeffectsofbackground noise.Itssensitivity alsocan approach thatofanidealquantum detector. Thephotomixing receiver ismorecomplicated thanthedirectphotodetection receiveranditrequiresastabletransmitter andlocaloscillator. Whenthetargetisinmotionrelativetotheradaralargedopplerfrequency shiftoccurswhich canplacetheechosignaloutsidethereceiverpassband. 
 COS COS ;COS COS  =AA AA Q     66XYSIN SINQQ    FOR SMALL VALUES OF  P  AND DEPRESSION ANGLE  E  WHERE 6X IS THE HORIZONTAL COMPONENT  OF VELOCITY PERPENDICULAR TO THE ANTENNA BORESIGHT AND  6Y IS THE COMPONENT ALONG THE  ANTENNA BORESIGHT  P  IS THE AZIMUTHAL ANGLE FROM THE ANTENNA BORESIGHT  OR THE INTERSEC 
 References [1] The Second World War 1939 –1945 —Royal Air Force, Signals Volume VI —Radar in Maritime Warfare, Air Ministry, 1954 (TNA AIR 10/5555) [2] Touch A G 1945 Chronological History of Airborne R.D.F. (1936-1941), BAC Washington (TNA AIR 20/1464)Airborne Maritime Surveillance Radar, Volume 1 8-5. [3] Smith R A, Hanbury-Brown R, Mould A J, Ward A G and Walker B A 1947 Detection of surface vessels by airborne radar (TNA AVIA 44/508) [4] Walker B A 1945 ASV Mark XIII, TRE Report T.1778 (TNA. 
 They are amenable to waveguide  construction and are heavier and bulkier than comparable diode devices. In summary, diodes and nonreciprocal ferrite phase shifters are viable competitors.  At L band and lower, diode phase shifters are an obvious choice. 
 CONSUMING AND EXPENSIVE PROCESS  PARTICU 
 For this reason, its fundamen- tal accuracy performance suffers. The fundamental accuracy of phase-only monopulse is identical to that of vector monopulse at boresight but degrades more rapidly off boresight. Full vector monopulse, using all the available infor- mation in the target returns, shows superior sensitivity at all target incidence an- gles. 
 Figure 1.22 - Bearing resolution.. 32Two identical 8 mile range PPI pictures taken on Raytheon 3 cm. and 10 cm. 
 In the case of anten - nas operated in close proximity to the ground, then both saf(t) and sar(t) are variant with  FIGURE 21.24  Coordinate system for scan description  (Courtesy IEE ) orz z zz x xxx yA SCAN B SCAN C SCANy yy ch21.indd   31 12/17/07   2:51:43 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 
 14. Ellis, J. G.: Digital MTI, A New Tool for the Radar User, Marconi Rev., vol. 
 THETIC APERTURE PROCESSING  CONJUGATE GRADIENT METHODS  AND REVERSE TIME MIGRATION ARE  EXTENSIVELY REPORTED IN THE LITERATURE -ANY OF THESE TECHNIQUES WORK WELL ON ISOLATED TARGETS SUCH AS PIPES  WHICH HAVE WELL 
 [\ \] [\}]76 \4    WHERE : IS THE SYSTEM OUTPUT )T IS FOUND THAT THE FOLLOWING FUNDAMENTAL EQUATION  APPLIES   7}    L- 2    WHERE L IS AN ARBITRARY CONSTANT VALUE 4HE BENEFIT OF USING THE 3,# CAN BE MEASURED  BY INTRODUCING THE JAMMER CANCELLATION RATIO *#2   DEFINED AS THE RATIO OF THE OUTPUT NOISE POWER WITHOUT AND WITH THE 3,#   *#2%6 %6%6 %6- -4- - 
 OFF VOLTAGE CAN VARY AMONG DEVICES FROM THE SAME WAFER  THE BIAS CONDITION MUST BE CHOSEN CARE 
 The magnitude and doppler  distribution of the echoes from the distant Earth’s surface (often termed backscatter ,  though that term should be reserved for monostatic radars) are major factors in setting  system dynamic range, spectral purity, and signal processing requirements.Chapter 20 ch20.indd   1 12/20/07   1:15:20 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 
 The accuracy of Oboe too is of a  higher order.  With Gee it is possible for a navigator to tell his pilot  . ELECTRONIC NAVIGATION I§I  how to get across some 300-400 miles of unknown  country and find a large town, without any guidance  other than the Gee master and slave transmisssion. 
 This sum is  1= 1  compared with a threshold as given by the right-hand side of Eq. (10.36). Therefore the  combined detector and integrator must have a law given by  DETECTION OFRADAR SIGNALS INNOISE383 detector werelinearwhilethevideointegrator hadasquare-law characteristic, thecombina­ tionofdetector andintegrator wouldbeconsidered squarelaw. 
 . 
 15.8 or Eq. 15.9 as appropriate. This particular distri - bution is representative of clutter from a relatively large radar footprint (pulse length  about 0.5 m sec or 75 meters) measured at intermediate grazing angles (20° to 70°) for  moderate wind speeds (about 15 kt). 
 cc 
 Atechnique thatcanoperateonthebasisofasingle pulse.andtherefore ismoreapplicable tothephasedarray,hasbeen c~lledthe~ approach; ormoredescriptively, the_.as.y.mmeU:U:.-.m.QltQll.Itl~!.48 Twoasymmetrical patterns are generated andsquinted abovethehorizontominimize response tothesurface-reflected signal. Thetwopatterns areconstrained sothattheirratio-,hasaneven-order symmetry aboutthe horizon. Knowing theshapeortheantenna patterns, themeasurement oftheratioofsignalsin thetwobeamsallowsthetargetelevation angletobededuced. 
 4RAIN 4HE AVERAGE SEPARATION BETWEEN #LOUD3AT AND #!,)03/ IS ABOUT  KM  WHICH CORRESPONDS TO A ONE 
 25-27, 1978, IEEE Publication 78 CH 13544 AES.  160. Malagisi, C. 
 0ROCESSING !PPROACH  "OSTON +LUWER !CADEMIC 0UBLISHERS     3 ! (OVANESSIAN   )NTRODUCTION TO 3YNTHETIC !RRAY AND )MAGING 2ADARS   .ORWOOD  -!  !RTECH (OUSE  &)'52%   #ONVENTIONAL AND &/0%. 3!2 IMAGES )N THE CONVENTIONAL IMAGE  TARGET VEHICLES   CANNOT READILY BE SEEN  WHEREAS IN THE &/0%. IMAGE THEY ARE QUITE PROMINENT 3OURCE HTTPWWWDARPA  MIL$!20!4ECH0RESENTATIONSSPO?PDF-OYER##4"7PDF                 !     
 defined as the probability that the value xis less than some specified value  • X  P(x)= I r(x)dx or d  p(x) = dx P(x) (2.19)  -00  In some cases, the distribution function may be easier to obtain from an experimental set of  data than the density function. The density functi<?n may be found from the distribution  function by differentiation.  2.5 SIGNAL-TO-NOISE RATIO  In this section the results of statistical noise theory will be applied to obtain the signal-to-noise  ratio at the output of the IF amplifier necessary to achieve a specified probability of detection  without exceeding a specified probability of false alarm. 
 MeteoroL, vol. 7, pp. 105-113, 1968. 
 SECOND DATA TRANSFERS #IRCUITS ARE TYPICALLY DESIGNED USING A HARDWARE DESCRIPTION LANGUAGE ($,   SUCH AS 6($, 6(3)# (ARDWARE $ESCRIPTION ,ANGUAGE  OR 6ERILOG 3OFTWARE TOOLS CON 
 The maximum RCS coincides with the nominal half-wavelength dimension or with the first resonance. The curves marked 45, 15, and 0° give the RCS as the target is rotated to these angles in the plane that contains the electric vector. The little sketches give, at the left, the body shape, then the RCS patterns at nominal !/2 wavelength, 1 wavelength, and 3/2 wavelength in order to help visualize how the RCS will change as the as- . 
 The depth of the first null can be predicted from Figure 2.45,  which is discussed later. For a radar system with relatively few hits per beamwidth, it is not advantageous to  use more than four or five different intervals because then the response to an individual  target will depend on which part of the pulse sequence occurs as the peak of the beam  passes the target. Random variation of the pulse intervals is not desirable (unless used  as an electronic counter-countermeasure feature) because it permits the nulls to be  deeper than the optimum choice of four- or five-pulse intervals. 
 SENSOR ELECTRONICS INTEGRATED  IN 3I'E 
 II units had been interchangeable but with ASV Mk. IIIB this was now no longer the case. The main changes were as follows. 
 S.: A New Microwave Reflector, IRE Natl. Contr. Record, vol. 
 11, pp. 49–52, June 1968. 41. 
 The speciﬁc operation steps of the proposed transformation method are as follows, ș( )11,șRs( ) 1,jșRs( )1M,șRs ( )1,ișRs( ),ijșRs( )M,ișRs ( )N1,șRs( ) N,jșRs( )NM,șRs Figure 8. The DEM image in the polar coordinate system. 1. 
 Record, Beijing, November 4–7, 1986, pp. 775–781. 64. 
 FREQUENCY (&  WAVELENGTHS TENS OF METERS  SCATTERING APPEARED TO ARISE FROM A RESONANT INTERACTION WITH SEA WAVES OF ONE 
 THE 
 STATE AMPLIFIERS FOR USE IN TRANSMITTER  DESIGN ARE OFTEN REFERENCED BY THEIR CLASS OF OPERATION !MPLIFIERS ARE DESIGNATED  AS OPERATING EITHER #LASS 
 Genaally,  such schemes are not so successful in practice as one would like. One of the fundamental  limitations is the foldover of nearby targets; that is, nearby strong ground targets (clutter) can  be quite large and can mask weak multiple-time-around targets appearing at the same place  on the display. Also, more time is required to process the data when resolving ambiguities. 
 IEEETrailS..vol.A[5-3 Supplement. no.6.pp.334-339. November. 
 Radar System Engineering  Chapter 6 – Radar Receiver Noise and Target Detection  36     accepted to be a Gaussian distribution.  As shown in Figure 6.8, a probability density p(R) of  the noise envelope R, which is a Rayleigh distribution, is the result at the output of the video  amplifier.   BIF BV IF stage detector video amp.UN € p(UN)dUN € p(R )dR   Figure 6.8  IF Stage, detector and video amplif ier of a Radar. 
   !)2"/2.% -4)  Î°x ABEAM  THE PREDOMINANT EFFECT IS THE VELOCITY SPREAD ACROSS THE ANTENNA BEAMWIDTH 4HESE  ARE CLASSIFIED AS THE SLANT 
 The main lobe (or main beam) of the pattern is a pencil beam (circular cross section) surrounded by minor lobes, commonly referred to as sidelobes. The angular scales have their origins at the peak of the main lobe, which is generally the electrical reference axis of the antenna. This axis may or may not coincide with the mechanical axis of the antenna, i.e., the axis of symmetry, sometimes called the boresight axis. 
  
 The harmonics of the difference frequency then become stronger relative tothe funda- mental. For example, ifthediscriminator crossover issetat30Me/see, corresponding toani-famplifier centered atthat frequency, asecond harmonic at30Me/see large enough toactuate the control circuit and cause locking may appear when the local oscillator isonly 15Me/see away from the magnetron frequency, under conditions ofAFC crystal saturation. The gain ofthe AFC feedback loop should behigh enough toinsure tight locking but not sohigh that the second harmonic can also cause locking. 
 44.Kittredge, F.,E.Ornstein, andM.C.Licitra, Millimeter RadarforLow-Angle Tracking, IEE£ EASCON '74Record,pp.72-75,IEEEPublication 74CHO883-1AES. 45.Barton,D.K.:Low-Angle RadarTracking, Proc.IEEE,vol.62,pp.687-704, June,1974. 46.Linde,G.J.:Improved Low-Elevation-Angle Tracking withUseofFrequency Agility,NavalResearch Laboratory Rept.7378,Washington, D.C.,Mar.17,1972. 
 Upconversion of exciter waveforms is similar to  downconversion within the receiver. Also, similar practical considerations of mixer  spurious and image rejection apply. The one significant additional challenge is the  rejection of the LO leakage. 
 It was believed that this would greatly aid ASV perform- ance. However, providing a suitable display that could readily be used by the pilotproved very dif ﬁcult, both in terms of wiring and receiver design, as well as practicality. During late 1941 and early 1942 three types of pilot ’s indicator underwent extensive service trials. 
 Friis: "Antennas, Theory and Practice," John Wiley & Sons. Inc.. Ncw  York, 1952. 
 It was reckoned that an ASV at that altitude might approach as close as 1 nmi before it was detected. However,ﬂying at 100 ft required a reliable and accurate radio altimeter, which was not available at that time. Attempts were being made in the UK to design a suitable radio altimeter but eventually type AYD altimeters from the USA were adopted forASV use, towards the end of 1943 when centimetric radar was entering service [ 2]. 
 PHASE APPROXIMATION OF  AN ,&- WAVEFORM (ERE  THE PULSE IS BROKEN UP INTO  - GROUPS  EACH OF WHICH IS  FURTHER BROKEN UP INTO  - SUBPULSES (ENCE  THE TOTAL LENGTH OF THE &RANK CODE  IS  -   WITH A CORRESPONDING COMPRESSION RATIO OF  - 4HE &RANK POLYPHASE CODES DERIVE THE  SEQUENCE OF PHASES FOR THE SUBPULSES BY USING A MATRIX TECHNIQUE AS FOLLOWS            ! !! "" " " " !        - - -- 
 Lewis, B. L., and I. D. 
 Aspect entropy is inversely proportional to the pseudo-probability P(k). If the scattering is strong in some angles, the aspect entropy will be lower. Consequently, the aspect entropy of an anisotropic target is lower because the scattering of an anisotropic target at certain angles is much stronger than at other angles. 
    AND  
 PULSE PHASE COHERENCE IS REQUIRED  THE STARTING PHASE IS RESET TO ZERO AT THE START OF EACH PULSE )F ALL THE ,/ FREQUENCIES USED ARE MULTIPLES OF THE PULSE REPLETION FREQUENCY  THE RESULTING PHASE WILL BE THE SAME FOR EACH PULSE 6#/S CAN BE USED TO CREATE A TUNABLE ,/ BUT ARE USUALLY PHASE LOCKED TO ANOTHER STABLE SOURCE FOR IMPROVED STABILITY 4HE TUNING VOLTAGE DESIGN AND FILTER CAPACITOR TECHNOLOGY USED TO ACHIEVE PHASE LOCK MUST BE CAREFULLY DESIGNED TO ENSURE RAPID VOLTAGE AND STORED CHARGE TRANSITIONS /THERWISE  THE 6#/ MAY PROPERLY ACQUIRE AND ACHIEVE PHASE LOCK  BUT THE RESIDUAL VOLTAGE DECAY FROM THE TRANSITION WILL MANIFEST ITSELF IN AN INSIDIOUS PHASE AMBIGUITY CALLED  POST 
 LOADED ANTENNA  AND THE CONTINUOUSLY  RESISTIVELY LOADED ANTENNA 4HE INPUT VOLTAGE DRIVING FUNCTION TO THE TERMI NALS OF THE ANTENNA IN  IMPULSE RADAR IS TYPICALLY A NARROW GAUSSIAN PULSE OF  PS  AND THIS REQUIRES THE IMPULSE RESPONSE OF THE ANTENNA TO BE EXTREMELY SHORT 4HE MAIN REASON FOR REQUIR 
 Broadly speaking, closed-loop methods are cheaper and simpler to implement than direct-solution methods.27' By virtue of their self-correcting nature, they do not require components which have a wide dynamic range or a high degree of linearity, and so they are well suited to analog implementation. However closed-loop methods suffer from the fundamental limitation that their speed of response must be restricted in order to achieve a stable and not noisy steady state. Direct-solution methods, on the other hand, do not suffer from problems of slow convergence but, in general, require components of such high accuracy and wide dynamic range that they can only be realized by digital means.27'29 Of course, closed-loop methods can also be implemented by using digital circuitry, in which case the constraints on nu- merical accuracy are greatly relaxed and the total number of arithmetic operations is much reduced by comparison with direct-solution methods. 
 Direc-  tions given to radar aerial-survey units from Oboe and  Gee stations can be checked on the spot by H2S, and for  135  . 136 HOW RADAR WORKS  scientific work of this nature the weight and cost of thi  equipment are not a serious disadvantage.  H2S could not be conceived until it was possible t  transmit radar pulses on wavelengths of a few centi. 
 128–132. 125. T. 
 Corisider the three targets labeled A, B, and C in Fig. 2.26~.  Target .I is located witliin the maximum unambiguous range Runamb [Eq. 
 572 INDEX  Antennas :  cosecant-squared, 55-56, 258-261  coverage patterns of, 446-447  cross level of, 273  delta-a scanner, 298  dielectric lens, 248-250  directive gain of, 224  double-curvature reflector, 259  Eagle scanner, 298  effective aperture of, 226-227  errors in, 262-264  far field of, 229  f/D ratio of, 239  feeds for, 236  field-intensity pattern of, 229  Fraunhofer region of, 229  Fresnel region of, 229  gain of, 224-226  ice, effect of, 240  lenses as, 248-254  low sidelobe, 227-228, 333, 549  Luneburg lens, 252-253  metal-plate lens, 250-252  mirror-scan, 242-244  motor drives for, 273  Mubis, 316  multimode feeds for, 164  multipath in, 442-447  n-bar scan, 178  near field of, 228  offset feed for, 239  organ-pipe scanner, 247-248  parabolic cylinder, 235-236  parabolic reflector, 235-243  parabolic torus, 236, 246-247  paraboloid, 235  pattern synthesis for, 254-258  polarization of, 227  polarization twist, 242-243  power gain of, 54, 225-226  radiation pattern of, 224, 228-235, 280-282  radomes for, 264-270  random errors in, 262-264  resonant frequency of, 179  scanning feed, 244-248  sidelobe radiation from, 227-228  sidelobes, in MTI, 145  in pulse doppler, 145-146  stabilization of, 270-273  surfaces for, 239-240  synthetic aperture, 517-529  systematic errors in, 262  Taylor illumination for, 257-258  torque fins for, 269 Antennas:  transreflect or, 242  twist reflector, 242-243  Aperture blocking, 223- 224, 239  in Cassegrain antenna, 241  by radomes, 266  Aperture efficiency, 228, 232  Aperture illtrminations, 228 235  Area MTI, 148  Array antennas, 2723-337  Array factor, 281 -282  Arrays:  beam steerlng of, 282-285  beam steering computer for, 323  Blass beam-forming, 3 1 1-3 12  computer control of, 322-328  constrained feed for, 306-308  conformal, 330-33 1  corporate feed for, 285  digital phase shifters for, 287-288  diode phase shifters for, 288-291  Dolph-Chebyshev, 257  dome, 329-330  duai-mode ferrite phase shifter for, 295-296  electromechanical phase shifters for, 297-298  elements for, 305-306  endfire, 279  errors in, 318-322  feeds for, 306310  ferrimagnetic phase shifters for, 291 -297  ferroelectric phase shifters for, 297  flux drive ferrite phase shifter for, 295  Fox phase shifter for, 296297  frequency-scan, 298-305  grating lobes in, 281, 283, 300, 332  hemispherical coverage, 328-329  Huggins phase shifters for, 303-305  hybrid-coupled phase shifter for, 289  latching ferrite phase shifter for, 293-294  lens, 308-309  limited scan, 334  linear, 279  loaded-line phase shifter for, 289  mixer-matrix feed for, 305, 308  MOSAR, 315  multifunction, 323  multiple beam, 3 10-3 18  mutual coupling in, 306  parallel-fed, 283, 285  parallel-plate feed for, 309  phase-frequency, 303, 334  phase-phase, 335  phase shifter quantization in, 32 1-322  phase shifters for, 286-298  572INDEX Antennas: cosecant-squared, 55-56,258-261 coverage patterns of,446-447 crosslevelof,273 delta-ascanner, 298 dielectric lens,248-250 directive gainof,224 double-curvature reflector, 259 Eaglescanner, 298 effective aperture of,226-227 errorsin,262-264 farfieldof,229 flDratioof,239 feedsfor,236 field-intensity patternof,229 Fraunhofer regionof,229 Fresnelregionof,229 gainof,224-226 ice,effectof,240 lensesas,248-254 lowsidelobe, 227-228, 333,549 Luneburg lens,252-253 metal-plate lens,250-252 mirror-scan, 242-244 motordrivesfor,273 Mubis,316 multimode feedsfor,164 multipath in,442-447 "-barscan,178 nearfieldof,228 offsetfeedfor,239 organ-pipe scanner, 247-248 parabolic cylinder, 235-236 parabolic reflector, 235-243 parabolic torus,236,246-247 paraboloid, 235 patternsynthesis for,254-258 polarization of,227 polarization twist,242-243 powergainof,54,225-226 radiation patternof,224,228-235, 280-282 radomes for,264-270 randomerrorsin,262-264 resonant frequency of,179 scanning feed,244-248 sidelobe radiation from,227-228 sidelobes, inMTI,145 inpulsedoppler, 145-146 stabilization of,270-273 surfaces for,239-240 synthetic aperture, 517-529 systematic errorsin,262 Taylorillumination for,257-258 torquefinsfor,269Antennas: transrcfkctor, 242 twistreflector, 242-243 Aperture blocking, 223-224, 239 inCassegrain antenna, 241 byradomes, 266 Aperture efficiency, 228,232 Aperture illuminations, 228235 AreaMTI,148 Arrayantennas, 278-337 Arrayfactor,281-282 Arrays: beamsteering of,282-285 beamsteeringcomputer for,323 .> Blassbeam-forming, 311-312 computer controlof,322-328 constrained feedfor,306-308 conformal, 330-331 corporate feedfor,285 digitalphaseshiftersfor,287-288 diodephaseshiftersfor,288-291 Dolph-Chebyshev, 257 dome,329-330 dual-mode ferritephaseshifterfor,295-296 electromechanical phaseshiftersfor,297-298 elements for,305-306 endfire,279 errorsin,318-322 feedsfor,30~310 ferrimagnetic phaseshiftersfor,291-297 ferroelectric phaseshiftersfor,297 fluxdriveferritephaseshifterfor,295 Foxphaseshifterfor,29~297 frequency-scan, 298-305 gratinglobesin,281, 283, 300,332 hemispherical coverage, 328-329 Huggins phaseshiftersfor,303-305 hybrid-coupled phase shifterfor,289 latching ferritephaseshifterfor,293-294 lens,308-309 limitedscan,334 linear, 279 loaded-line phaseshifterfor,289 mixer-matrix feedfor,305,308 MOSAR,315 multifunction, 323 multiple beam,310-318 mutualcoupling in,306 parallel-fed, 283,285 parallel-plate feedfor,309 phase-frequency, 303,334 phase-phase, 335 phaseshiflerquantization in.321-322 phaseshiftersfor,286-298. INDEX 573  Arrays:  postamplification beam forming, 310-31 1  quantization in, 321-322, 334  radiation pattern of, 280-282  random errors in, 318-322  reflectarray. 309  Reggia-Spencer phase sliifter for, 291 -293  series-fed. 
   
 Ê*," 
 PULSE CANCELER AND  D" FOR A  
 Thisincrease in signal-to-noise corresponds toareduction inrangebyafactorof3.28.Therefore, ifthe characteristics ofthctargetcrosssectionarenotproperly takenintoaccount, theactual performance oftheradarmightnotmeasure uptotheperformance predicted asifthetarget crosssectionwereconstant. Figure2.22alsoindicates thatforprobabilities ofdetection greaterthanabout0.30,agrcatersignal-to-noise ratioisrcquired whenthefluctuations are uncorrclated scantoscan(cases 1and3)thanwhenthefluctuations areuncorrelated pulseto pulse(cases2and4).Infact.thclargerthenumberofpulsesintegrated, themorelikelyitwill beforthefluctuations toaverageout.andcases2and4willapproach thenontluctuating case. CurvesexistIl..nforvariousvaluesofhitsperscan,II,thatgivethesignal-to-noise ratio perpulseasafunction ofPdand11f'Thesignal-to-noise ratioperpulsecanbeusedintheform oftheradarequation asgivenbyEq.(2.32).Itisnotnecessary, however, toemploysuchan elaborate setofdatasinceformostengineering purposes thecurvesofFigs.2.23and2.24may beusedascorrections totheprobability ofdetection (asfoundinFig.2.7)andastheintegration improvcment factor(Fig.2.Ra)forsubstitution intotheradarequation ofEq.(2.33).. 
 The switch then passes beacon signals onevery cycle inwhich themodu- lator pulse does not occur. This equipment gave reasonably satisfactory results initsfinal form. Inspite ofalltheprecautions taken, however, the considerable interfer- ence from radar and communications equipment, together with the presence ofdiffraction minima, limited the reliable operating range to about 30miles when the interference was severe, and to50miles orso under reasonably favorable conditions. 
 Plant, and G. R. Valenzuela, “Observation of breaking ocean waves with coher - ent microwave radar,” in Wave Dynamics and Radio Probing of the Ocean Surface , chap. 
 COMPARISON MONOPULSE TRACKING RADAR IS THE MOST  COMMONLY USED MONOPULSE SYSTEM (OWEVER  THE THREE SIGNALS MAY SOMETIMES BE  COMBINED IN OTHER WAYS TO PERFORM WITH A TWO 
 BEAM TARGET   THE ESTIMATION ERROR IS  OBTAINED FROM THE FOLLOWING EQUATION 4HEN  SUBSTITUTING %Q  INTO  AND SOLV 
 l2] Cook, C.E., and Bernfeld, M., Radar Signals - An Introduction to Theory and  Application , New York: Academic Press, 1969.   [3] Cook, C.E., and Paolillo, J., "A Pulse Compression Predistortion Function for  Efficient Side lobe Reduc tion in a High -Power Radar", Proceedings lEEE , vol. 52,  pp.377- 389, April 1964. 
 TIONS IN THE DIGITAL SEQUENCE OUTPUT TO THE $! CONVERTER  A RESULT THAT IS UNDESIRABLE IN PULSE DOPPLER APPLICATIONS 4RULY RANDOM ERRORS ARE NOT GENERATED BY THE DIGITAL PORTION OF THE $$3 4HE ONLY  NONDETERMINISTIC ERRORS ARE A RESULT OF THE $! CONVERTER PERFORMANCE IN THE FORM OF INTERNAL CLOCK JITTER OR ADDITIVE THERMAL NOISE AND THE EFFECT OF THE PHASE NOISE ON THE INPUT CLOCK SIGNAL )NTERNAL $! CONVERTER CLOCK  JITTER PRODUCES PHASE MODULATION O F THE OUTPUT SIGNAL  PROPORTIONAL TO THE OUTPUT FREQUENCY 3IMILARLY  PHASE NOISE PRESENT ON THE CLOCK INPUT SIGNAL IS TRANSFERRED TO THE OUTPUT SIGNAL  REDUCED BY LOG  FOUT  FCLK  D" $! CON 
 TIIC large attertuations experienced at millimeter  wavele~~gtlis is onc of the cllief reasons long-range, ground-based radars are seldom found  above 35 (;Hz (K, hand).  The attenuation of the attnospheric gases decreases with increasing altitude. Thus the  altct~t~atiorl cxpcricr~cccl fly a r;itl;ir will del~erld oti the altitude of the target as well as the  range. 
 V, Division 14, "Radar," available from Office of  Technical Services, U.S. Department of Commerce.  2. 
 ING THE RELATIVE VELOCITY OF A TARGET &- 
 In the real situation, the radar scans over the  target, and decisions that are highly correlated are made at every pulse. Hansen13 ana- lyzed this situation for N = 2, 4, 8, and 16 pulses and calculated the detection thresh - olds shown in Figure 7.4, the detection performance shown in Figure 7.5, and the  angular accuracy shown in Figure 7.6. Comparing Hansen’s scanning calculation with  the single-point calculation, one concludes that about 1 dB of improvement is obtained  by making a decision at every pulse. 
 More  details of the relationship between A/D converter and receiver SNR are included in  Sections 6.10 and 6.11. ch06.indd   5 12/17/07   2:02:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 H. Long and K. A. 
 FT HIGH PLANAR 8 
 DISCRIMINATING SCATTEROMETER CONTROL AND  DATA 
 TANEOUS LOBING  RADAR °ÓÊ  " "*1 - 
 74.2 DOPPLEREFFECT Complete descriptions of the doppler phenomenon are given in most physics texts, and a discussion emphasizing radar is to be found in Skolnik3 (chap. 3, pp. 68-69). 
 DICTABLE RADIATION PATTERNS AND BEAM 
 LOG INPUT SIGNAL  XT  IS SHOWN IN &IGURE A  WITH THE SIGNAL SPECTRUM CENTERED AT   &  HERTZ 4HE SIGNAL IS SAMPLED BY THE !$ CONVERTER AT FREQUENCY  &S  PRODUCING THE  TIME SEQUENCE  XN  AND FREQUENCY SPECTRUM  8 W CENTERED AT FREQUENCY  V WITH THE  IMAGE CENTERED AT  
 DRIVEN SEA CLUTTER IN THE OPEN OCEAN ,ABORATORY MEASUREMENTS BY -OORE ET AL  WITH ARTIFICIAL hRAINv SUGGESTED THAT  FOR LIGHT WINDS THE BACKSCATTER LEVEL INCREASED WITH THE RAIN RATE  WHILE FOR HEAVY WINDS RAIN MADE LITTLE DIFFERENCE %XTENSIVE MEASUREMENTS AT + U BAND IN THE OPEN OCEAN  TENDED TO CONFIRM THIS BEHAVIOR )N MEASUREMENTS IN NATURAL RAIN  OVER #HESAPEAKE "AY  (ANSEN FOUND THAT EVEN  A LIGHT RAIN  MMH  CHANGES THE SPECTRAL CHARACTER OF SEA CLUTTER AT MODERATE WIND SPEEDS  MS  BY INTRODUCING A SIGNIFICANT HIGH 
 Inthis case, the pulser components are reduced toapulse-forming network, acharging transformer (which com- bines thefunctions ofinput step-up transformer and charging inductance), and arotary gap mounted onthe shaft ofthealternator which supplies power tothe charging transformer. Inthis way, theproper relationship between supply and repetition frequencies iseasily maintained, and avery compact pulser forhigh power output canbemade, although such apulser has noflexibility. Ingeneral, line-type pulser circuits aresimpler and therefore easier to service. 
 Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 17 .28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 Shadows.  The simplest method of measuring object height is to observe the length  Lshadow  of the shadow of the object cast by the SAR and calculate the object height h  from the known SAR altitude H and ground range Rg:  h LH Rg= ⋅shadow  (17.51) This expression assumes flat-earth, and may be generalized to curved-earth if Rg is  relatively large; see Section 3.2.2 of Sullivan.1 However, the shadow method works only  for an isolated, relatively high object on essentially flat terrain (e.g., Figure 17.9). 
 TO 
 Battan, L. J .: "Radar Observation of the Atmosphere," Vnil'. of Chicago Press, Chicago, Ill., 1973. 
 It can be found that the phase distortions of the above SAR image pair are similar, which means that most of the distortion phase will be o ﬀset during the interference process. Therefore, the phase error introduced by the process of interference is small, as shown in Figure 15. Figure 15. 
 TERM FUTURE OF RACONS IS UNSURE  ALTHOUGH MARITIME AUTHORITIES ARE ASSESS 
 It would reduce the signal- processing load if a reference function could be applied over a region. This, too, can be done, but range walk and defocusing set limits to the size of a patch which can be handled in this manner. Of the methods that have been proposed, the use of polar format and its generalization and the collection of a . 
  
 1955. 38.Withers. M.J.:Matched FilterforFrequency-Modulated Continuous-Wave RadarSystems, Proc. 
 A. Eshleman, and J. M. 
 ................................ ................................ ........ 
 Ilnrtori. I). K.: " Rntlars. 
 Theechosignalfromanisolated targetvariesinversely asthefourthpoweroftherange, asiswellknownfromtheradarequation. Withthisasacriterion, thegainofthelow­ frequency amplifier shouldbemadetoincrease attherateof12dB/octave. Theoutputofthe amplifier wouldthenbeindependent oftherange,forconstant targetcrosssection.Amplifier response shaping issimilarinfunction tosensitivity timecontrol(STC)employed inconven­ tionalpulseradar.However, inthealtimeter, theechosignalfromanextended targetsuchas thegroundvariesinversely asthesquare(ratherthanthefourthpower)oftherange,sincethe. 
 -Ê1- ÊÊ , ", 
 Simpson, P. J.: Mechanical Aspects or Ground-Based Radomes, Chap. 12 or .. 
    
 So far, a variety of techniques have been applied in near-ﬁeld 3-D imaging to improve its performance, such as imaging based on range migration algorithm (RMA) [ 12–14] and polar format algorithm (PFA) [ 14], tomography imaging method [ 15], microwave holography method [ 16], confocal radar-based imaging [ 17], and NUFFT-based imaging [ 18,19]. Sensors 2018 ,18, 3750; doi:10.3390/s18113750 www.mdpi.com/journal/sensors 153. Sensors 2018 ,18, 3750 Imaging approaches as mentioned above are all based on the traditional Nyquist sampling principle and matched ﬁltering. 
 The sheets  are stacked one on top of the other as shown on the left side of Figure 25.3 b, and the  resulting portion of the sampled signal spectrum from 0 to the sampling rate of B is  generated by adding the spectra of the stacked pages together, as shown on the right.  FIGURE 25.3  (a) Bandlimited, real signal spectrum before sampling, ( b) portion of sampled spectrum  from 0 to B, and ( c) full sampled signal spectrum0 B0 B/2 B 2B –B –2Bfreq freq(a) (b) (c)–B/2 0 B/2 B 2B –B –2B –B/2B/2 ch25.indd   3 12/20/07   1:39:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 High-PRF pulse doppler radars use a low- frequency stopband filter to reject these velocity regions along with main-beam clutter. Low-PRF AEW radars bypass these censor circuits in the portion of the surveillance region that is over water. This allows slow-moving shipping targets to be detected. 
 FREQUENCY INSTRUMENTATION SYSTEMS ON STATIC RANGES CAN COLLECT 2#3 PATTERNS AT HUNDREDS OF FREQUENCIES FOR A SINGLE ROTATION OF THE TEST TARGET 4HE SIGNAL 
 July. 1955.  4. 
 areceiver isinserted ateachendofthefeed.Theechosignalfromaparticular direction is(received atoneoftheslotsandisdividedinthewaveguide feed.The'twosignals travelinopposite directions andarcreceived ateachendofthefeed.Thephasedifference between thetwosignals(orthedifference intraveltime)depends onfromwhichslotthey originated. whichinturndepends ontheelevation angleofarrival.Thusameasurement of phasedifference resultsinameasurement ofelevation angle. Adetailed analysis oftheaccuracy ofthephase-in-space technique isnotavailable. 
 quantify the endless battle between ECCM and ECM techniques. Nevertheless, a commonly adopted approach to determine the ECM effect on a radar system is based on evaluation of the radar range under jamming conditions. The advantage of using specific ECCM techniques can also be taken into account by calculating the radar range recovery. 
 Moore, G. J. Stossmeister, J. 
 Thus a measurement of  phase difference results in a measurement of elevation angle.  A detailed analysis of the accuracy of the phase-in-space technique is not available, but in  one implementation it has been said34 to have a potential elevation accuracy of about 0.2°.  Multipath reflections can also degrade the accuracy of this method, but since the phase-in­ space technique employs multiple heams to shape its elevation pattern. 
 PULSE BINOMIAL CANCELER   PULSE 
 (An alternative to decreasing the dynamic range is to depend on a cell- averaging constant false alarm rate (CA-CFAR) processor after the signal processing  to provide a threshold that rides over the residue noise, but the efficacy of this method  depends on the residue noise being completely noise-like, which is unlikely.) After addressing the unstable pulse-compression sidelobes, it is still necessary to  control detections from residue caused by the spectral spread of the clutter or by low  frequency transmitter power supply ripple. This can be accomplished by limiting the  maximum signal amplitude at the input to the canceler. The process described above  is depicted in Figure 2.81. 
 Kretschmer, Jr., “A new class of polyphase pulse compression codes and  techniques,” IEEE Trans ., vol. AES-17, pp. 364–372, May 1981. 
 CALLY EXPRESSED IN DECIBELS D"  4HIS PARAMETER IS DETERMINED BY A VARIETY OF FACTORS INCLUDING THE MIXER INTERMODULATION SPURIOUS DESCRIBED IN MORE DETAIL IN 3ECTION    THE SPURIOUS CONTENT OF THE RECEIVER LOCAL OSCILLATORS  THE PERFORMANCE OF THE !$ CONVERTER  AND THE MANY SNEAK PATHS THAT MAY RESULT IN UNWANTED SIGNALS COUPLING ONTO THE RECEIVER SIGNAL PATH )NTERMODULATION $ISTORTION )-$   )NTERMODULATION DISTORTION IS A NONLINEAR PRO 
 Radar has been used extensively for the study of thunderstorms, squall lines,  tornadoes, hurricanes, and in cloud-physics research. Not only is radar useful as a means of  studying the basic properties of these phenomena, but it may also be used for gathering the  information needed for predicting the course of the weather. Hurricane tracking and tornado  warning are examples of applications in which radar has proved its worth in the saving of life  and property. 
 A filter bank covering the doppler  frequency range is of advantage in some radar applications and offers another option in the  design of MTI signal processors. Consider the transversal filter that was shown in Fig. 4.1 1 to  have N - 1 delay lines each with a delay time T = llf,. 
 In this paper, we analyze the error caused by ArcSAR imaging on reference plane. The method of extracting DEM on ground range for assisted ArcSAR imaging is also given. Besides, DEM accuracy and deformation monitoring accuracy of proposed method are analyzed. 
 Moreover, it can effectively solve the problem that the accuracy of target scattering azimuth is not high in different directions by adopting sub-aperture synthesis. As veriﬁed by tests, target 3-D views with higher quality can be obtained by applying the imaging approach as proposed in this paper, so as to provide reliable judgment basis for target identiﬁcation and other applications. Since this paper adopts an OMP-based reconstruction approach, the calculation complexity is not high. 
 Stepped- and swept-frequency instrumentation systems on  static ranges can collect RCS patterns at hundreds of frequencies for a single rotation  of the test target. The signal-to-noise ratio can be improved when necessary by means  of multisweep or multistep signal integration schemes. The price paid for much of  this versatility is the requirement for more active test time per target rotation, thereby  increasing measurement costs. 
 This relationship is written #TO ~ 1 (21.58) Finally, it is useful to express the radar cross section a in terms of the azimuth and range resolution, 8az and 8r, as well as in terms of the reflectivity of the ter- rain, p. The radar cross section is equal to the reflectivity of the terrain multiplied by the projected area. This projection accounts for the term sin \\i. 
 Tuley, Radar Cross Section , Raleigh, NC: SciTech Publishing,  Inc., 2004, p. 254. 15. 
 591–605, May 1973. 54. W. 
 SPHERE  STRONG DIRECTIONAL INTERFERENCE  AND CLUTTER ECHOES FROM BEYOND THE MAXIMUM UNAMBIGUOUS RANGE )N ADDITION  THE RADAR DESIGNER NOW HAS THE OPTION TO COMPENSATE FOR SIGNAL PATH FLUCTUATIONS IN BOTH SPATIAL AND TEMPORAL DOMAINS  WITHIN LIMITS  BY EMPLOYING PROCESSING SCHEMES THAT DIAGNOSE THE NATURE OF THE SIGNAL CORRUPTION ON A FIRST PASS AND THEN REPROCESS WITH ALGORITHMS THAT COMPENSATE FOR THE OBSERVED CORRUPT 
 A. Holm: Meteorological Applications of Synthetic Aperture Ra- dar, final report, Project A-2101, Engineering Experiment Station, Georgia Institute of Technology, 1979. 84. 
 the gain is 0.99 that at infinity.  The plot of the electric field intensity I E(O, 1>) I is called the field-intensity pattern of the  antenna. The plot of the square of the field intensity I E(O, 1>) 12 is the power radiation pattern  I'(O. 
 Therefore, it offers poor protection against nearby transmissions during the interpulse period  or when the radar is shut down.  The passive diode-limiter without any bias current is operable at all times, but it is  capable of handling much less power than the active limiter with bias. Thus its use as an all  solid-state limiter is restricted to low power systems, perhaps handling less than 1.5 kW peak  power.45 When it can be used, the diode limiter has the advantage of fast recovery time (about  1 ~ts for 1 kW peak power, and 50ns for 100 W);j3 no spike leakage; low flat leakage; reason-  able loss, size and weight; and it can have a long life.40  Passive TR-limiter. 
 STATE RADAR v )%%% %!3#/.    PP n   % ,  #OLE  0 ! $E#ESARE  - * -ARTINEAUS  2 3 "AKER  AND 3 - "USWELL  h!32 
 .L 
 Appl.  Meteorology. vol. 
 Subscript S-receiving components. R=distance from interrogator tobeacon ~aI,le units, A=wavelength oftheradiation 1.. P=power inwatts. 
 Radar  waves are diffracted around the curved earth in the same manner that light is diffracted by a  straight edge. The ability of electromagnetic waves to propagate around the earth's curvature  by diffraction depends upon the frequency, or more precisely, upon the size of the object  compared with the wavelength. The lower the frequency, the more the wave is diffracted. 
 FERENCE 2&)  SOURCES FROM VERY LONG DISTANCES 2&) CAN ARISE F ROM UNINTENTIONAL AND  INTENTIONAL ANTHROPOGENIC EMITTERS IN THE USER 
 1976. Phila. PA. 
 ALARM 
 On non-SOLAS radars, the antenna rotation rate is specified to be not less than 20 rpm  but is not directly specified for SOLAS-approved radars. In practice, antennas for existing  shipborne radars normally rotate at 25–30 rpm; on high-speed craft, the rotation rate is  typically 40–45 rpm. For SOLAS vessels, the antenna must be able to start and operate in  relative wind speeds up to 100 kt; other environmental requirements for the antenna system  are detailed in IEC 60945,12 where there are specific tests for “exposed” equipment. 
 Ambiguities inthe measurement ofdoppler frequency canoccurinthecaseofthediscontinuous measurement of Fig.4.2c.hutnotwhenthemeasurement ismadeonthebasisofasinglepulse.Thevideo signalsshowninFig.4.2arecalledbipolar, sincetheycontain bothpositive andnegative amplitudes. Moving targetsmaybedistinguished fromstationary targetsbyobserving thevideo outputonanA-scope (amplitude vs.range).AsinglesweeponanA-scope mightappearasin Fig.4.)a.Thissweepshowsseveralfixedtargetsandtwomoving targetsindicated bythetwo arrows. Onthehasisofasinglesweep.moving targetscannotbedistinguished fromfixed targets.(Itmayhepossible todistinguish extended groundtargetsfrompointtargetsbythe stretching oftheechopulse.However, thisisnotareliablemeansofdiscriminating moving fromfixedtargetssincesomefixedtargetscanlool<.likepointtargets,e.g.,awatertower.Also, somemoving targetssuchasaircraft nyinginformation canlooklikeextended targets.) Successive A-scope sweeps(pulse-repetition intervals) areshowninFig.4.3btoe.Echoesfrom fixedtargetsremainconstant throughout. 
 A part of the power is fed into a reference channel and builds the magnitude and phase reference.  The passing signal is radiated from the transmitting a n- tenna.   The polarimetric antenna system consists of 2 antennas, each with orthogonal polarization (vertical and horizontal). 
 Thermal •  Can be a major  driver. •  Radars are typically  high power. •  High power densities  at feed or feed array  are common. 
 The Range-height Indicator.—Any off-centered PPI can be used asarange-height indicator bysubstituting elevation angle for azimuth, providing the indicator can follow the scanner involved. In most cases, itisdesirable topresent height onascale that isconsiderably expanded incomparison tothat used forthe display ofground range. Inconsequence the most adaptable PPI techniques arethose inwhich each cartesian coordinate ha?itsown amplifier which permits thedesired height expansion tobeprovided simply byincreasing the gain ofthe proper channel. 
 M., and I. L. Davies: Information Theory and Inverse Probability in Telecommunica­ tions, Proc. 
 CHIP CIRCUIT DESIGNS THAT HAVE BEEN REPORTED FROM 5(& THROUGH MILLIMETER 
 Instead of weighting the received-signal spectrum to reduce the time sidelobes, it is  possible, in principle, to.achieve the same affect by amplitude·weighting either the envelope of  transmitted FM signal or the received signal. J n the case of linear FM with large pulse­ compression ratio, the amplitude weighting applied to the time waveform is of the same form  as the weighting applied to the frequency spectrum, for the same output response. 24  Amplitude-modulating the transmitted signal is not usually practical in high-power radar  Table 11.1 Properties of weighting functions  Peak Main lobe Side lobe  sidelobe Loss width decay  Weighting function dB dB (relative) function  Uniform -13.2 0 1.0 I /t  0.33 + 0.66 COS2 (nf/B) -25.7 0.55 1.23 I /1  cos2 (nf/ B) -31.7 1.76 1.65 I /t 3  Taylor (n = 8) -40 1.14 1.41 I /t  Dolph-Chebyshev -40 1.35 I  0.08 + 0.92 cos2 (nf!B) (Hamming) -42.8 1.34 1.50 1/r  B = bandwidth . 
 The rotary spark gap, because ofitsgreat simplicity and high power handling ability, has been widely used asaswitching device. Figure 10.43 shows schematically how arotating insulating disk pierced by tungsten pins serves thefunction ofaswitch. Asthedisk revolves and a rotating pin approaches afixed pin, the electric field strength becomes. 
 Angle Indices.—Because oftheir simplicity, fixed angle indices ruled onatransparency arewidely used inspite oftheinaccura- cies described above. The inherent data are usually farless accurate than those ofrange. Furthermore, inmany applications, such asthat ofhoming, theangle ofinterest changes slolvly ifatalland there istime forrepeated observations. 
 The first Radar to be constructed completely with  transistors is described in [LiW], and operated at 35 GHz.  It operated in pulse mode with a resolution of approximately 2m.  The frequency for this was internationally coordinated at the  beginning of the 1970’s. 
 Fifty simulations are averaged to reduce speckle bias. As shown in Figure 13a, the values of Δσare the same in two parallel look directions, such as 0◦ and 180◦, which indicates the same visibility of eddy spirals under two parallel look directions. Moreover, Figure 13a,b shows that there is a considerable value difference of Δσbetween two orthogonal look directions; however, the value difference of Δσris relatively small. 
 Phase Uniformity.  The change of insertion phase of the limiter with amplitude is  less of a concern for modern radar systems that operate primarily in the linear operat - ing region. However, maintaining constant insertion phase during limiting preserves  the phase of target returns in the presence of limiting clutter or interference. 
 SEC. 11.2] COAXIAL LINES 397 since nocurrent flows across it. Asimilar improvement ismade onthe center conductor. 
 POLARITY 3!2 ARCHITECTURE FIRST USED BY THE -INI 
 0HYSICS ,ABORATORIES  %0, -ODEL !4, 
 351-356, July, 1975.  74. Andrews, G. 
 (3.12a)l.  Similarly, on the decreasing portion, the beat frequency &(down) is the sum of the two  [Eq. (3.12b)l. 
 GROUND ECHO  16.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Different wavelengths are sensitive to different elements on the surface. One of the  earliest known and most striking directional effects is the cardinal-point  effect in returns  from cities: Radars looking in directions aligned with primary street grids observe stron - ger regular returns than radars at other angles. Horizontally polarized waves are reflected  better by horizontal wires, rails, etc., than are vertically polarized waves. 
 WORLD PROPAGATION  SIGNIFICANTLY MODIFYING THE EFFECTIVE AMBIGUITY FUNCTION u 4HEY MUST BE ABLE TO ACHIEVE THE DESIRED MEASUREMENT CAPABILITY IN THE PRESENCE OF EXTREMELY STRONG GROUND CLUTTER u 4HEY MUST BE DESIGNED SO AS TO MINIMIZE DISTORTION OR CORRUPTION BY THE IONOSPHERIC MEDIUM OR  AT LEAST  ENABLE SUCH DISTORTION TO BE ESTIMATED AND MITIGATED BY SIGNAL PROCESSING AFTER RECEPTION u 4HEY MUST HEED THE CONSTRAINTS ON PEAK VERSUS AVERAGE POWER IMPOSED BY THE (& TRANSMITTING EQUIPMENT AND ANTENNAS 4HE WAVEFORMS USED IN MOST OPERATIONAL (& SKYWAVE RADARS ARE VARIATIONS ON THE  PERIODIC LINEAR FREQUENCY 
 W. D.: Double Null Technique for Low Angle Tracking, Microwave J .• vol. 19, pp. 
 Thepulsecompression ratioisameasure ofthedegreetowhichthepulseiscompressed. It isdefined astheratiooftheuncompressed pulsewidthtothecompressed pulse\tidth,orthe product ofthepulsespectral bandwidth Bandtheuncompressed pulsewidthT.Generally, BT}>I.Thepulsecompression ratiomightbeassmallas10(13isamoretypicallowervalue) oraslargeaslOsorgreater, Valuesfrom100to300mightbeconsider~d asmoretypical. Therearemanytypesofmodulations usedforpulsecompression, buttwothathaveseenwide application arethelinearfrequency modulation andthephase-coded pl/Ise. 
 The diagram of Fig. 9.5 is a parallel configuration. Series or series-parallel  configurations are possible. 
 A memorandum of a meeting of the Air Ministry [ 4] recorded the plan to produce 25 sets by the end of 1943 and a further 75 sets by February 1944. Incidentally, it was noted that automatic frequency control (AFC) was due to be introduced in the future (see discussion on ASV Mk. VIB). 
 J. Joss. and R. 
 All these  stages must be stable to achieve good MTI performance. ch10.indd   16 12/17/07   2:19:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 In statistical terms it is  claimed to be a uniformly most powerful test and is an optimum one, no matter what the a  priori probabilities of signal and noi~e.~"he Neyman-Pearson criterion is well suited for  radar application and is usually used in practice, whether knowingly or not.  376INTRODUCTION TORADAR SYSTEMS parallelchannels, eachcontaining adelaylinecorresponding toaparticular valueofT"as wellasamultiplier andlow-pass filter.Insomeapplications itmaybepossible torecordthe signa"!onsome storage medium, andatahigherplayback speedperform thesearchsequen­ tiallywithdifferent valuesofT,..Thatis,theplayback speedisincreased inproportion tothe numberoftime-delay intervals T,.thataretobetested. Sincethecross-correlation receiverandthematched-filter receiverareequivalent math­ ematically, thechoiceastowhichonetouseinaparticular radarapplication isdetermined by whichismorepractical toimplement. 
 ACTERIZED BY A FAIRLY WIDE BANDWIDTH  " !S AN EXAMPLE  CONSIDER A CARRIER FREQUENCY    F    '(Z AND A  BANDWIDTH  "    '(Z /NE WAY TO ACHIEVE THIS BANDWIDTH NOT  THE BEST WAY  IN GENERAL  BUT A WAY THAT IS EASY TO DESCRIBE  IS TO USE A  STEP 
 Theseattributes areobtained foraprice,sothattheyshouldonlybeconsidered whenwarranted. Itisnot obvious thattheyarealwaysabsolutely essential forthesuccessofaparticular application. Forexample, itiscertainly truethatamechanically scanned reflector antenna cannot switchabeamfromonedirection toanother asfastascanaphased-array antenna. 
 /" £{]£x]Îä]ÈÈqnÇ 4HE BISTATIC RADAR CROSS SECTION 2#3  OF A TARGET  R" IS A MEASURE  AS IS THE MONOSTATIC  RADAR CROSS SECTION  R-  OF THE ENERGY SCATTERED FROM THE TARGET IN THE DIRECTION OF THE  RECEIVER "ISTATIC CROSS SECTIONS ARE MORE COMPLEX THAN MONOSTATIC CROSS SECTIONS IN THE OPTICAL REGION SINCE  R " IS A FUNCTION OF ASPECT ANGLE AND BISTATIC ANGLE  A  4HREE  BISTATIC 2#3 REGIONS ARE OF INTEREST IN THE OPTICAL REGION PSEUDO 
 TIES AND UNBALANCE  THESE MIXERS PRODUCE ONLY TWO OUTPUT FREQUENCIES  EQUAL TO THE SUM AND THE DIFFERENCE OF THE TWO INPUT FREQUENCIES 4HE NONLINEARITIES AND IMBALANCE OF MIXERS IS DESCRIBED IN MORE DETAIL IN 3ECTION  4HE BEST RADAR RECEIVER IS ONE WITH THE NARROWEST 2& INSTANTANEOUS BANDWIDTH COM 
 The feed is placed at one focus of the hyperboloid and the paraboloid focus at the other. A similar antenna is the gregorian, which uses an ellipsoidal subreflector in place of the hyperboloid. The parameters of the Cassegrain antenna are related by the following expressions: tan i|v/2 = 0.25/V/^ (6.17) I/tan i|/v + I/tan i|ir = If8ID8 (6.18) l-l/* = 2Lr/fc (6.19) where the eccentricity e of the hyperboloid is given by e = sin [(i|iv + iM/2]/sin [(i|iv - v)v)/2] (6.20) The equivalent-paraboloid4'26 concept is a convenient method of analyzing the radiation characteristics in which the same feed is assumed to illuminate a virtual reflector of equal diameter set behind the subreflector. 
   PP n    7 +OCH  h/N "AYESIAN -(4 FOR WELL SEPARATED TARGETS IN DENSELY CLUTTERED ENVIRONMENT v IN  0ROC )%%% )NTERNATIONAL 2ADAR #ONFERENCE    PP n  $ * 3ALMOND  h-IXTURE REDUCTION ALGORITHMS FOR TARGET TRACKING IN CLUTTER v  30)%  3IGNAL AND  $ATA 0ROCESSING OF 3MALL 4ARGETS   VOL   PP n    2 * 0RENGAMAN  2 % 4HURBER  AND 7 ' "ATH  h! RETROSPECTIVE DETECTION ALGORITHM FOR EXTRAC 
 This formula becomes exact in the optical limit of vanishing wavelengths and is  probably accurate to 10 or 15 percent for radii of curvature as small as 2 l or 3l. It  assumes that the specular point is not close to an edge. When applied to dielectric  objects, the expression should be multiplied by the square of the voltage reflection  coefficient associated with the material properties of the object. 
 416-198, Oct. 2, 1969.  95. 
  
 S. Goldstein, “A dual-pulse repetition frequency scheme  for mitigating velocity ambiguities of the NOAA P-3 airborne doppler radar,” J. Atmos. 
 30–63,  July 1976. 116. D. 
 OF 
 ● The scene may change between passes due to wind, etc. ● Example results are given by Schuler et al.,53 who perform “terrain topography  measurement using multipass polarimetric SAR.” Single-pass InSAR : ● Baseline is relatively well known, providing consistency throughout synthetic aperture. ● Scene is same for both images since data for each are collected simultaneously. 
 17. 196 1.  107. 
 6.12. it  rcscr~ihlcs tlic rnilgllctl.o~l oscilliitor cxccl~t tliat there are two exterrlal couplings (an input arid  output). ISlectrons origi~intc fro~ii tlic cyli~idrical catliode whicli is coaxial to tlie KF slow-wave  circuit that acts as tlie anode. 
 Keeler and Frush77 discuss design considerations for a rapid- scanning doppler radar. Any rapid-scanning approach generally must encompassHORIZONTALDISTANCE SOUTH OF CP-2 (km) . X'(km) FIG. 
 DATED ON A SINGLE ANTENNA TO COMBINE THE COMPLEMENTARY FEATURES OF TWO 2& BANDS   ! USEFUL COMBINATION OF BANDS IS 8 BAND  '(Z  AND +A BAND  '(Z  4HE   8 
 R. Sheen, S. Shackman, and D. 
  n.   -4) 2!$!2  Ó°Ç£ 4IME JITTER OF THE TRANSMITTED PULSES RESULTS IN DEGRADATION OF -4) SYSTEMS 4IME  JITTER RESULTS IN FAILURE OF THE LEADING AND TRAILING EDGES OF THE PULSES TO CANCEL  THE  AMPLITUDE OF EACH UNCANCELLED PART BEING  $TS  WHERE  $T IS THE TIME JITTER AND  S  IS THE  TRANSMITTED PULSE LENGTH 4HE TOTAL RESIDUE POWER IS  $TS    AND THEREFORE THE LIMITA 
   )43 
 Although itmayhe employed tocoveralimitedsector-as doestherasterscan-nodding scanmayalsobeused toobtainhemispherical coverage, thatis,elevation angleextending to90°andtheazimuth scanangleto360°. Thehelicalscanandthenodding scancanbothbeusedtoobtainhemispheric coverage withapencilbeam.Thenodding scanisalsousedwithheight-finding radars.ThePalmer, spiral,andrasterscansareemployed infire-control tracking radarstoassistintheacquisition ofthetargetwhenthesearchsectorisoflimitedextent. 5.8OTHER TOPICS Servosystem.Theautomatic tracking ofthetargetcoordinates inangle,range,anddoppler frequency isusuallyaccomplished withaso-called TypeIIservosystem.1.2·3.67.68 Itisalso referred toasazerovelocityerrorsystemsinceintheorynosteady-state errorexistsfora constant velocity input.Asteady-state errorexists,however, forastep-acceleration input. 
 t973. pp. 112 111. 
 ING BY A CONDUCTING SPHERE IS KNOWN AS THE -IE SERIES  AND IS SHOWN IN &IGURE  .OTE THAT THE CHART IS SPLIT ROUGHLY INTO THREE REGIONS )N THE  2AYLEIGH REGION BELOW  KA     THE 2#3 RISES WITH THE  FOURTH POWER OF THE SPHERE RADIUS  A N ECHO DEPENDENCE  CHARACTERISTIC OF ELECTRICALLY SMALL BODIES  WHETHER SPHERICAL OR NOT )N THIS REGION  THE INCIDENT WAVE CANNOT ACCURATELY RESOLVE BODY LENGTH 
 For a pulsed radar, with a pulse repetition period (PRT) T, R(T) is obtained from the simple expression8 (N-I) *(fl = r;2JJ*+i^ (23.35) yv(*=o) where the sk are the complex signal samples (sampled at the radar PRT) in a given range gate and s*k is the complex conjugate. It is clear that this algorithm requires only N complex multiplications for a time series of TV samples while the FFT re- quires N Iog2 N. This pulse-pair algorithm, as it is often called, therefore not only is an excellent estimation technique but is less complex and costly than compa- rable FFT processors. 
 FIG. 21.5 STAR-I radar imagery, lower Lake St. Clair, upper Detroit River. 
           . 
 16.Lee,Y.W.,T.P.Cheatham, Jr.,andJ.B.Wiesner: Application ofCorrelation Analysis tothe Detection ofPeriodic SignalsinNoise,Proc.IRE,vol.38,pp.1165-1171, October, 1950.. 3% INTRODUCTION TO RADAR SYSTEMS  17. Lee, Y. 
 It is often convenient to treat the drop or particle size distribution as a continuous  function with a number density N(D), where N(D) is the number of drops per unit  volume having diameters between D and D + dD. In this case, Z is given by the sixth  moment of the particle size distribution,  Z n D D dD =∞∫( )6 0 (19.8) If the radar beam is filled with scatterers, the sample volume of V is given10   approximately by  Vr c≈π θφ τ2 8 (19.9) where q and f are the azimuth and elevation beamwidths, c is the velocity of light, and  t is the radar pulse width. Substituting Eqs. 
 PULSE REPETITION 
 TO 
 Figure 20.28 shows a performance prediction for a hypothetical radar in the form  of an oblique sounding. A typical skywave radar is supported by one or more verti - cal sounders and oblique backscatter sounders for transmission-path analysis and to  aid in radar-frequency management. Of course, the radar itself is an oblique sounder,  but its sounding data is restricted to the frequency, waveform, and scan program of  its primary surveillance task. 
 Crystals which pass this test aresafe inaproperly operating radar set. Table 11.2 lists forcomparison therejection-limit specifications ofthe most widely used crystals inthethree radar bands. The bearing ofthese figures ontheover-all sensitivity limit ofmicrowave receivers isdiscussed inChap. 
 FIQ. 15.S.—Beacon receiving antenna mounted above lower-beam radar antenna. Airborne beacons have been provided, almost without exception, with vertically polarized antennas. 
 14.21  14.9 FM Radar   ................................................................  14.21  14.10 Sinusoidal Modulation  ............................................  14.23  Double Sinusoidal M odulation  ............................ 
 D" RESOLUTION WIDTH ACHIEVED BY STRETCH PROCESSING IS THE SAME  AS THAT ACHIEVED BY THE MATCHED FILTER FOR THE ,&- WAVEFORM 4HE  
 Ascan beseen from Fig. 1630, the locking-test channel delays a sample ofthelocking pulse bymeans ofashort auxiliary supersonic delay line, and then mixes this sample with the received signal. Ifreflecting end cells areused, multiple reflections within thedelay line will give rise toanumber ofequally spaced locking pulse echoes. 
 SUREMENTS AND OF ERRORS  IS EMPLOYED TO PROVIDE A BETTER ESTIMATE OF AIRCRAFT VELOCITY  !LTHOUGH THIS PROCEDURE CAN BE PERFORMED OVER LAND OR WATER  SEA CURRENTS MAKE OVER 
 NOISE PEAKS ARE GENERALLY ACCOMPANIED BY A DIP OR FADE IN AMPLITUDE ! SLOW !'# SYSTEM THAT DOES NOT MAINTAIN CONSTANT SIGNAL LEVEL DURING RAPID CHANGES ALLOWS THE SIGNAL LEVEL TO DROP DURING A RAPID FADE  REDUCING SENSITIVITY VOLTS PER DEGREE ANGLE ERROR  DURING THE LARGE ANGLE 
 D" RANGE RESOLUTION WIDTH FOR (AMMING WEIGHTING IS   $2C "  (AMMING 7EIGHTING     2ANG E 7INDOW 7IDTH  4HE WIDTH OF THE RANGE WINDOW IS ESTABLISHED BY THE BAND 
 IEEE Geosci. Remote Sens. Lett. 
 October. 1974.  CWANDFREQUENCY-MODULATED RADAR99 27.Klass.P.J.:NavyImrroves Accuracy. 
 R., and R. L. Mitchell: Detection Probabilities for Log-Normally Distributed Signals,  IEEE Trans., vol. 
 489 -492.  81. 1)ratic. 
  
 - 15  31  45  . iV. ON THE SCREEN  Function of the CRT in a radar receiver—  Physical construction of a typical radar CRT  —How the electron stream is created, beamed,  and controlled—Afterglow screens—Sensi-  tivity of electrostatic and electromagnetic  tubes—X and Y plates—A typical Type A  radar display—Showing where the target is  to be found. 
 For two-angle tracking such as azimuth and elevation, the feeds may include three or more apertures.6 Single apertures are also employed by using higher-order waveguide modes to extract angle- error-sensing difference signals. There are many tradeoffs in feed design because optimum sum and difference signals, low sidelobe levels, omnipolarization capa- bility, and simplicity cannot all be fully satisfied simultaneously. The term sim- plicity refers not only to cost saving but also to the use of noncomplex circuitry which is necessary to provide a broadband system with good boresight stability to meet precision-tracking requirements. 
 TOOTH WAVEFORM AT A RATE BETWEEN  AND  SECONDS PER  -(Z !LL RECEIVED PULSES ARE RESPONDED TO BUT THE INTERROGATING RADAR WILL RECEIVE A RACON BURST ONLY ONCE EVERY ONE TO TWO MINUTES WHEN ITS RECEIVER IS IN BAND TO THE PARTICULAR TRANSMISSION )!,! RECOMMENDS THAT RACONS HAVE SUPPRESSION TECHNIQUES TO AVOID RESPONDING  TO RADAR SIDELOBE TRANSMISSIONS 4HIS IS NOT AN EASY TASK TO IMPLEMENT AND PROBABLY IMPOSSIBLE TO MAKE INFALLIBLE "ASICALLY  THE RACON NEEDS TO BUILD A TABLE OF RADAR SIG 
 The fired TR-tube gap isnot a perfect short circuit. Ifthevoltage across thearcisV,theleakage power going tothe receiver isV2/Z, where Zisthe impedance looking toward the receiver, measured atthe gap terminals. The voltage can bemade smaller byhaving thedischarge take place inagasatapressure ofonly a few millimeters ofmercury. 
 Thereflectivity factorZofEq.(13.19),whichwasdefinedasthesumofthesixthpowerof theparticles' diameter perunitvolume,wasbasedontheassumption ofRayleigh scattering. Whenthescattering isnotRayleigh, aquantity similartoZisdefined,whichiscalledthe t'qliil'll/ent radarre!lectil'it yfactorZ<,givenby70.73 (13.24) where /1istheactualradarreflectivity, orbackscatter crosssectionperunitvolume,andIK 12 istakenas0.93. Insteadoftherainfallrater,theintensity ofprecipitation issometimes statedintermsof thedBrellectivity factorZ=2001'(6.ordOz=10logZ.ArainfallrateofImm/hequals 2.1dOz.4rnm/hequals3JdOz.and16rnm/hequals42dBz.(Thismaybeanincorrect usage oftheprecisedefinition ofdecibels asapowerratio,butitisthejargonusedbytheradar meteorologist. 
 Koch69 © IEEE 1995 ) ch07.indd   40 12/17/07   2:14:42 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 The computer allows the radar  to utilize its resources effectively by scheduling the execution of the various functions so as  to perform the more important tasks first.  A multifunction array radar might be called upon to perform the following tasks:  Search of a specified volume of space at a specified rate, and the detection of targets.  Track initiation, or transition to track, after a new detection is established. 
 ÊÊ   Ê, "76 
 Oct. 11 15,  1976. pp. 
 IMPULSE 
 AND 
 This page has been reformatted by Knovel to provide easier navigation. Contents     xix   12.4 Fading of Gr ound Echoes  .......................................  12.12  Fading-Rate Computations  ................................ 
 ~ lnjJ/A. > 0.11], where the theory underestimates the experi­ mental observations.71. 72  The rcnection of electromagnetic waves from the sea may be separated into a coherent and  an i11colterem component.71 73 The coherent component has a reflection coefficient whose  amplitude and phase are fixed by a given geometry and sea state. 
 Three main approaches—adaptive threshold, nonparametric detectors, and clutter maps—have been used to reduce the false- alarm problem. Adaptive thresholding and nonparametric detectors assume that the samples in the range cells surrounding the test cell (called reference cells) are independent and identically distributed. Furthermore, it is usually assumed that the time samples are independent. 
 Brindly, A. E., et al.: A Joint Army/Air Force Investigation of Reflection Coefficient at C and Ku Bands for Vertical, Horizontal and Circular System Polarizations, HT Re- search Institute, Final Rept., TR-16-61, AD-A031403, Chicago, July 1976. 122. 
 Arrays:  postamplification beam forming, 310-311  quantization in, 321-322, 334  radiation pattern of, 280-282  random errors in, 318-322  reflect array. 309  Reggia-Spcnccr phase shifter for, 291-293  series-fed, 285  signal management in, 324  snake feed for. 30 I  space-fed. 
 LOOK 3!2 FOLLOWS THE 2AYLEIGH DISTRIBUTION ACTUALLY THE EXPONENTIAL DISTRIBUTION IF SQUARE 
 Luenburger, “On Barker codes of even length,” Proc. IEEE , vol. 51, pp. 
 Brit. I RE.49)  2.5 dB per doubling mentioned above. The applicability of these particular tests to the usual  PPI display can be questioned since a 5-inch-diameter CRT was used with simulated echoes  placed at an azimuth unknown to the operator at a distance of 1 inch from the center of the  scope. 
 (14.8)  yields  v C - < f < --- S,, - - 2R,  510INTRODUCTION TORADAR SYSTEMS equaltotheone-way patternoftheconventional antennaofthesamelength,butwithone-half thebeamwidth. Thetwo-way patterns withuniform weighting, assuming smallangles,are approximately SAR-+sin[21t(Lej).)sin8] 21t(Lej).)sin8sin2[1t(Lj).)sin8] realarray-+[1t(Lj).)sin8]2 (14.7)Thusthetwo-way beamwidthoftheSARantenna isnarrower thanarealradarantenna ofthe sameaperture size(ifitcouldbebuilt),butthesidelobes arenotaslowanddonotdropoff withincreasing angleasfast.Two-way sidelobes of13.2dBintheSARarenotsatisfactory for mostpurposes. Weighting ofthereceived signals,similartotheweighting oftheaperture illumination ofarealantenna, isoftenappliedtoreducethesidelobe levels. 
 Three relevant examples of  radar applications well suited to the use of reflector antennas are briefly described below. Low Cost Radar.  For very cost-constrained applications where mechanical scan  rates suffice, reflector antennas are still the dominant choice. 
 Specific radiolocation frequency ranges may be found in the “FCC Online Table of Frequency  Allocations,” 47 C.F.R. § 2.106.  7. 
 Thus the radar  resource of time is affected more by the long-range targets, and the radar power is more  affected by the tactical function.  The data processor, as well as the radar, can cause the system to run out of available tune.  The time required to process each target dwell as well as the amount of computer memory  needed per target is usually independent of the target range. 
 121. E. Brookner and J. 
 STATE TRANSMITTERS TO HIGH 
 pp. 487-492, September/October. 1960. 
 The extended target simulation corroborates the experiment result of point target that the degeneration of PSLR and ISLR induced by scintillation will seriously distort the imaging performance. Figure 14. The Monte-Carlo simulation results of the scintillation effect on point targets. 
 7.9~ and b. These two arrangements are examples of rear  feeds. The waveguide rear feed shown in Fig. 
 T.: Stepped Amplitude Distributions, IEEE Trans., vol. AP-12, pp. 515-516, July 1964. 
 ING RECEIVE ENERGY IN ADJACENT BEAMS ! NARROW AZIMUTH BEAMWIDTH ON TRANSMIT AND RECEIVE AND STACKED RECEIVE BEAMS PROVIDE GOOD RADAR ANGLE RESOLUTION !ZIMUTH COV 
 not usually enjoyed by monostatic radar. A CW radar requires considerable isolation  hetween transmitter and receiver to prevent the transmitted signal from leaking into the  receiver. Isolation is ohtainc<l in the bistatic radar because of the inherent separation between  transmitter and receiver. 
 TION OF AIRCRAFT RANGE 
 GROUND ECHO  16.556x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 For Figure 16.48 a and b, the depression angle and type are the parameters, whereas  for Figure 16.48 c, the terrain slope is the parameter. The lines are based on linear  regression on the logarithmic frequency scale with the exception of desert and grass  at very low depression angles where a quadratic regression was used. Note that urban,  mountain, and forest tend to have relatively high values compared with agriculture and  uncultivated land with moderate slopes. 
 vol. AP-23. pp. 
 BASED .,&- WAVEFORM WITH  K     A TANGENT 
 The ribs resume their required struc- tural shape as they unwind (under constraint), thereby stretching the mesh into the proper parabolic shape. The Lockheed development program was initiated to demonstrate the readiness of large-diameter offset reflector technology through development of ground-testable, flight-representative full-size hardware. The Seasat-A antenna (designed by Ball) is a 10.74- by 2.16-m microstrip array that is deployed after orbit insertion. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 23.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 or target azimuth and elevation measurements can be converted to qR.1 Beam-splitting  techniques can be used to reduce the measurement error. 
 98. Shrader, W. W.: Antenna Considerations for Surveillance Radar Systems, Seoerrrll ..lntrliul E~st Corrst  Conference on Aeronatrtical and Navigatiot~al Electronics, Baltimore, Md., October, 1960. 
 %##- INTERAC 
 The peak sidelobe ratio (PLSR) along the range direction shown in Figure 11bi s−13.2242. The integral sidelobe ratio (ISLR) along the range direction is −9.8468. The PLSR along the azimuth direction shown in Figure 11bi s−13.2611. 
 17111 tllc fltrclrratior1s a1.c r11orc 1.apid tllari in case I and are taken to bc independent from  13r1lsc 10 ptllsc irlsfcact of fro111 scn~ to scan.  ('(IS(! 3. 111 this C;ISC'. 
 24.6  24.6 Radar Cross Se ction  ..............................................  24.10  24.7 Noise and Interf erence  ...........................................  24.12  24.8 Spectrum Use  ......................................................... 
 SIGNAL DISCRIMINATION, RESOLUTION AND CONTRAST The factors that influence the dkcernibility ofasimple radar echo signal against thermal noise have been discussed inChap. 2and inthe early sections ofChap. 12. 
 27-29, 1969, IEEE Publication 69 C 31-AES.  46. Barton, I). 
 Two defocused ships are detected in Gaofeng-3 images. ( a) Sub-image of ship03 located in the Gaofeng-3 image; ( b) Sub-image of ship 04 located in the Gaofeng-3 image. The red rectangles are the zoomed sub-images. 
 The ratio by which the targ& echo power may be weaker than the  coincident clutter echo power and still be detected with specified detection and false-  alarm probabilities. All target radial velocities are assumed equally likely. A subclutter  visibility of, for example, 30 dB implies that a moving target can be detected in the  presence of clutter even though the clutter echo power is 1000 times the target echo  MTIANDPULSEDOPPLER RADAR129 threshold fromthe16rangecellsandaclutterthreshold fromthec1uttcrmaparecalculated forfilters2and8adjacent tothczero-velocity filter,andthelargerofthetwoisusedasthe threshold. 
 State-of-the-art radar altimeters can measure  the resulting slopes to a 1-microradian precision. Standard gravityInduced surface slopeDeflected gravity Ocean Ocean floor with seamount ch18.indd   41 12/19/07   5:15:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 3.1–3.5. 93. R. 
 Symp. , University of Illinois, 1983. 116. 
 UNITS  UNDER  STANDARD ATMOSPHERIC CONDITIONS TO A NEGATIVE SLOPE DECREASING  - 
 Because it has virtually constant phase velocity at all frequencies, the helix permits TWTs to have bandwidths in excess of an octave. However, the helix TWT has not been used in high-power radars because high power requires a high-voltage beam, and the resulting electron velocity is too fast to synchronize with the low velocity of the RF wave on a helix slow-wave circuit. The limit of helix tubes is about 10 kV and a peak RF power output of a few kilowatts. 
 High attenuation might be a desira~e attribute  for a short-range radar that is required to avoid mutual interference with distant radars or to  avoid being detected at long range (if a military radar). However, the relatively high attenua­ tion in this part of the spectrum is a serious ohstaclt! to achieving long-range radar.  The attenuation of electromagnetic energy in the portion of the electromagnetic spectrum  above 10 GHz is shown in Fig. 
 BASED COMPUTERS v IN  !#-3)'$!  )NTERNATIONAL 3YMPOSIUM ON &IELD 0ROGRAMMABLE 'ATE !RRAYS   -ONTEREY  #!  &EBRUARY    PP n   % " (OGENAUER  h!N ECONOMICAL CLASS OF DIGITAL FILTERS FOR DECIMATION AND INTERPOLATION v  )%%%  4RANS ON !COUSTICS  3PEECH  AND 3IGNAL 0ROCESSING  !330 
 A. Skillman: Pulse Doppler Radar, chap. 19 of" Radar Handbook." M. 
 Moreover, radars at higher frequencies also facilitate the observation of eddy features. To our knowledge, a comparable agreement between observed and simulated radar signatures of the shear-wave-generated eddies at more than one frequency, look direction and wind ﬁeld has never been conducted in previous studies. SAR imaging of oceanic eddies is affected by radar parameters and environmental factors, and the simulation method proposed in this paper can facilitate research on eddy features by changing radar parameters and environmental conditions. 
 Afixedphasedarrayrequires electronic beamsteering that complicates theradar.Iftheflexibility ofanelectronically steeredarrayisnotneeded,the advantages ofanarrayantenna forcombining theradiated powerfrommanyindividual sourcescanbehadbymechanically sc~nning theentireantenna. Aseparate solid-state source canbeusedateachelementoftheantenna, oranumberofsourcescanbecombined tofeed eachrow(oreachcolumn) asintheAN{fPS-59, Fig.6.15.38Themechanically rotatingarray antenna withsolid-state transmitters hassomespecialproblems ofitsownthatmustbe overcome. Onesuchproblem istheneedtoconveylargepowertothesolid-state deviceson therotating ~ntenna. 
 TION IS THE USE OF THE RADAR APERTURE AS A HIGH POWER  HIGH GAIN PRIMARY DATALINK ANTENNA   ,INK &REQ "AND $ATA 2ATE KBS  %##- !2# 
 May, 1974.  2 1. Maines, J. 
 The radar equation will also be considerably different if  clutter echoes or external noise, rather than receiver noise, determine the background with  which the radar signal must compete. Some of these other forms of the radar equation are  given elsewhere in this text.  Accuracy of the radar equation. 
 The resulting voltages con- tain ad-c component ofmagnitude C(with respect tothedetector bias point) and avarying component ofamplitude D,the sum being always positive. The d-ccomponent can beprevented from affecting thefinal device byrelating itsbias level properly tothat ofthe detector. The scheme ofadding aconstant a-fcomponent tothesignal isintended to preserve thephase sense ofthecomponents varying sinusoidally with the scanner rotation; inthis case itisconsiderably simpler than transmitting areference signal tobeused inkeying aphase-sensitive rectifier. 
 , &U AND ! #AZANAVE EDS   3AN $IEGO !CADEMIC  0RESS    PP n  * 'OLDHIRSH AND * 2 2OWLAND  h! TUTORIAL ASSESSMENT OF ATMOSPHERIC HEIGHT UNCERTAINTIES  FOR HIGH 
 I.: The Effects of the Turbulent Atmosphere on Wave Propagation, TT68-50464, Na­ tional Technical Information Service, Springfield, VA, 1971.  113. Atlas, D.: Meteorological "Angel" Echoes, J. 
 PULSE FILTER IS  . TIMES  THE SIGNAL 
 6.31 Shaped-Beam Antenna Design  ..........................  6.32  Antenna Size  .....................................................  6.33  Accuracy  ........................................................... 
 15.9. Choice ofWavelength.-In the discussion ofother parameters, the consideration ofwavelength was necessarily included; the many factors influencing choice ofwavelength will now besummarized. Component development has been concentrated onparticular wave- length bands. 
 17.2 and 175. 2Inorder that pulses passing through the three-pulse coincidence circuit shall not cause false coincidences, they should follow each other byatleast the sum ofthe code length and the pulse length—in this case atotal of8ysec.. 728 RADAR RELAY [SEC. 
 ERROR  MEASUREMENT ERRORS ARE GIVEN IN 4ABLE  4YPICAL BIAS AND NOISE OF TARGET RANGE MEASUREMENT ERRORS IN A PRECISION 
 1.12  Size  ...................................................................  1.12  Shape  ................................................................  1.12  Other Target Measurements  .............................. 
 PULSE  FEEDBACK CANCELER 3EE TEXT FOR FIVE 
 However, it is the Rice distribution that  follows from such a model.67 The Rice probability density function is  l+s [ u l ( p(a) = exp -s --{l + s) /0 2  O'av O'av !!:_ s(l + s)),  Uav (2.4 I}  wheres is the ratio of the radar cross section of the single dominant scatterer to the total cross  section of the small scatterers, and I 0( ) is the modified Bessel function of zero order. 38 This is  a more correct description of the single dominant scatterer model than the chi-square with  m = 2. However it has been shown that the chi-square with m = 2 approximates the Rice when  the dominant-scatterer power is equal to the total cross section of the other, small scatterers,  and so long as the probability of detection is not large.41 . 
 InAugust 1940 acontract forquantity production ofthis equipment was let.. 182 THEGATHERING ANDPRESENTATION OFRADAR DATA [SEC. 6.10 The setwas built both formobile use (SCR-270) and forfixed-station installation (SCR-271). 
  "ANDWIDTH -(Z         !$ 3.2 IN    .YQUIST "7D"  !$ #ONVERTER    3AMPLE 2ATE-(Z  !$ &ULL 3CALE ,EVEL D"M 
 19. Upton, L. O., and G. 
 SIGHT #ONSERVATIVE DESIGN SUGGESTS THAT THE MEASUREMENT SHOULD BE CONCENTRATED NEAR THE REFLECTION FROM THAT SURFACE (ENCE  OCEAN 
 14.18  Doppler Tracke rs  ...............................................  14.18  Constant False-Alarm Rate (CFAR)  ...................  14.19  14.7 Minimization of Feedthrough  .................................. 
 Track mai11re11a11ce, or track update, by acquiring new data and consolidating it with existing  tracks.  User serrices, whereby the specific information desired by the user is acquired, such as obtain­ ing a satellite ephemeris or the solution of a fire-control problem. 324 INTRODUCTION TO RADAR SYSTEMS  In each of these, the proper radar waveform must be selected along with the corresponding  receiver processing. 
 Jezek, K. Farness, R. Carande, X. 
 Olsen, “Nonparametric radar extraction using a generalized sign test,”  IEEE Trans ., vol. AES-7, September 1981. 32. 
 Analysis shows that RC must besmall compared with thetime ofone r-fcycle forefficient recti- fication. The effects ofRand Ccan beminimized bysmall contact area, and itispossible tomake crystals with nearly asgood conversion +20, , r 1111111.Lefficiency aswould beobtained from asimple diode atmuch lower fre- [quenc~es. The conversion loss, de-+15 2 fined asratio ofr-fsignal power toi-fc “;+10 signal power, runs from 5to8dbfor &. 
 The  other implementation is to insert a phase s~ifter in one branch of the delay-line canceler and  adjust its phase to shift the null of the frequency response. (A phase shift \JI in one branch of the  canceler corresponds to a frequency shift 2nfd = \JI /Tp, where TP = pulse repetition interval.)  The clutter-doppler-frequency compensation can, in some cases, be made open loop by  using the a priori knowledge of the velocity of the platform carrying the radar and the  direction of the antenna pointing. This is more practical with a shipborne radar rather than  with an airborne radar. 
 TO 
 The key difference is that the transmitter signal is generated at low level, as precisely as desired, and is amplified all the way from there to the required peak power level. As shown in Figs. 15.44 and 15.45, the change in the system block diagram is small, just the direction of two arrows and the change from oscillator to amplifier for the high-power RF source; but there is a huge difference in the hardware re- quired to implement the amplifier chain system, including many stages of RF am- plification, each with its own power supplies, modulator, and controls; and all these stages must be stable to achieve good system MTI performance (Chap. 
 As a consequence of the two-way path the phase dimerence between the equally  spaced elements of a synthetic array is twice that of a conventional array with the same  spacing. (The terms synthetic array and synthetic aperture are used interchangeably here.)  Agaln the factor k will be taken to be unity.  rhere are two fundamental limits to the maximum effective length of the synthetic aper-  ti11.e. 
 If considerable amplitude tl~ictuation  noise were to appear at the conical-scan or lobe-switching frequencies, it could not be readily  eliminated with filters or AGC. A typical scan freqliency might be of the order of 30 fir.  Higher frequencies might also be used since target amplitude noise generally decreases with  increasing frequency. 
 Army byanAmerican manufacturer was called SCR-540. Inthis set, which operated near 200 Me/see, asingle transmitting antenna sent abroad lobe inthe forw-ard direction from the aircraft. Two pairs ofreceiving antennas were provided; one pair produced overlapping lobes like the “homing” lobes oftheASV Mark II,togive anindication (also identical with that ofthe ASV Mark II)ofthe homing error inazimuth. 
 (ILL "OOK #OMPANY    ' 6 "ORGIOTTI  #HAPTER  IN  4HE (ANDBOOK OF !NTENNA $ESIGN  ! 7 2UDGE  + -ILNE  ! $ /LVER  AND 0 +NIGHT EDS   VOL   ,ONDON 0ETER 0EREGRINUS  ,TD    + ' 3CHROEDER  h.EAR OPTIMUM BEAM PATTERNS FOR PHASE MONOPULSE ARRAYS v  -ICROWAVES    PP n  -ARCH   * &RANK  h0HASED ARRAY ANTENNA DEVELOPMENT v *OHNS (OPKINS 5NIVERSITY  !PPL 0HYS ,AB  2EPT 4'   PP n  -ARCH   7 % 3CHARFMAN AND ' !UGUST  h0ATTERN MEASUREMENTS OF PHASED ARRAYED ANTENNAS BY FOCUS 
 4.15. The weighting factors shown on the feedback  paths apply to tile characteristic of Fig. 4.14~. 
 An echo  fluctuation of this type will be referred to as scan-to-scan fluctuation. The probability-  . ' I. 
 Atlas, P. Eccles, R. Fetter, and E. 
 COHERENT 4HE SAME OSCILLATORS ARE USED IN BOTH  TRANSMIT AND RECEIVE BUT NOT NECESSARILY COHERENT WITH EACH OTHER 4HE RESULT IS THAT THE PHASE OF THE TARGET REMAINS CONSTANT  BUT THE PHASE OF MANY OF THE SPURIOUS SIGNALS VARIES FROM PULSE TO PULSE )N THIS TYPE OF CONFIGURATION  SIGNAL ISOLATION AND FREQUENCY ARCHITECTURE IS CRITICAL TO MINIMIZE THE OCCURRENCE OF SPURIOUS SIGNALS THAT COULD ERRO 
 3,  pp. 1110–1120, July 1995.  8. 
 25.10. Each region can be modeled, by a semiempiricaI process (con- taining arbitrary constants that are adjusted to fit empirical data), as follows. The low-grazing-angle and bistatic scatter regions are based on the constant-^ monostatic clutter model: OA,0 = 7 sin 0/: (25.20) where <JA/° is the monostatic scattering coefficient, 6, is the monostatic, or inci- dent, angle on Fig. 
 Parts of the waveguide are made ofnickel electrodeposited onadie-cast form which issubsequently melted out. The scan iscircular, at30rpm. This scanner hasanunusual feature which allows themain axis tobe adjusted toavertical attitude despite changes inthe angle ofattack of the airplane. 
 SUM  IE  ISORANGE CONTOURS  FROM EACH TRANSMITTER 
 Thus, byswitching theazimuth receiver from one feed to another, thebeam pattern ofthereceiving antenna can beswitched from one totheother oftwo overlapping lobes equally displaced inazimuth on opposite sides ofthe normal tothe antenna array. Similar switching arrangements are provided forthe elevation antenna and itsreceiving channel. The antennas are mounted onasingle cross arm, which rotates in azimuth with acentral pedestal enclosing the radar circuits and can be turned about itsown axis toelevate the arrays. 
 12 The median value of the theoretical distribution in this case  was equated to the median of the actuaJ data and the O' was selected to minimize the maximum  difference in dB between the theoretical curve and the actual data.  With many radars that operate in the presence of sea clutter the Rayleigh pdf generally  underestimates the range or values obtained from real clutter, and the log-normal pdf tends to  overestimate the range of variation. Several other analytical probability density functions that  lie between these two extremes have been suggested for modeling the actual statistical . 
 17.13c), turning one onand the other off. The screen grids, normally atcathode potential, receive the positive sine pulse. If thepulse arrives when thecontrol.grid ofagiven tube ison,that tube will produce anegative pulse onitsplate. 
 MINED BY REQUIRING THE ADAPTED ESTIMATION ERROR BE ORTHOGONAL TO THE OBSERVED VEC 
 In recent years they have also dominated the automobile Radar sensors market.   A superimposed Doppler signal  € fD increases the IF -frequency (beat frequency)  € fB when the  target is approaching (up -ramp) while decreasing it when the target is departing (down -ramp).   With Figure 7.8 this is demonstrated for an approaching target using triangular modulation. 
 1SeehIicrowave Receivers, I’ol 23, Chap. 10. SEC.12.8]PROTECTION AGAINST E-YTRANEO USRADIATIONS 461 -y————------- ---------- -—I,.———..-....—. 
 must be enough to induce target amplitude fluctuations while not causing too much beam steering—a difficult tradeoff in some applications. Sequential-lobing angle estimation techniques are also vulnerable to time-varying or amplitude- modulation jammers such as blinkers. The fact that RF frequencies correspond one to one with elevation angle in the frequency-scanned radar constrains it in the use of frequency agility for electronic counter-countermeasures (ECCM) pur- poses. 
 They are often called pseudorandom (PR) or pseudonoise (PN) sequences. A typical shift-register generator is shown in Fig. 10.9. 
 If the result of applying the technique of Eq. (12.18) to a set of measurements indicates that CT° probably did vary across the significantly illuminated area, this variation may be used as a first approximation to determine a function /(9) de- scribing the 6 variation of a°, and a next-order approximation then becomesFIG. 12.13 Typical receiver input-output curve. 
 Ó°È  2!$!2 (!.$"//+  ABOVE  EVEN IF EACH TRANSMITTED PULSE HAS FREQUENCY MODULATION OR OTHER ARTIFACTS  AS  LONG AS THE ARTIFACTS ARE IDENTICAL PULSE 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°ÎÇ THE MODEL STATES 4HE UPDATE EQUATION FOR THE  ITH MODEL DEPENDS NOT ONLY ON THE ITH  MODEL STATE BUT ALSO ON THE STATES OF ALL OTHER MODELS 4HESE STATES ARE MIXED USING  INFERRED PROBABILITIES OF THE TARGET TRANSITIONING FROM ONE MOTION MODEL TO ANOTHER !S AN EXAMPLE  CONSIDER RADAR TRACKING  OF A BALLISTIC MISSILE THAT UNDERGOES DISTINCT  PHASES OF FLIGHT BOOST  EXO 
 GENERATED MISMATCHES IN THE WAVEGUIDE BECOMING RESONANT 4HIS CREATES A TILTED PHASE FRONT ACROSS THE ARRAY  WHICH CAUSES THE BEAM TO SQUINT TO AN ANGLE THAT IS FREQUENCY DEPENDENT )NDIVIDUAL MANUFACTURERS PRO 
 The validi­ ty of these adjustments is not as readily assessable via  surface truth correlations as is that of the wave height  and gain control/wind-speed data. The long-term drift  of the height measurement can be monitored during the  signal injection phase of the on-board calibrate mode.  A sample of the transmitted pulse is coupled into the  receiver, processed through the system, and tracked as  a point target. 
 The planar mirror rotates the plane of polarization  90° on reflection. The beam will illuminate the target twice for every revolution of the planar  mirror. However, the scanning is not continuous in angle, and the time between observations  alternates between two values. 
 1531-1539, 1975. 65. Fujita, T., and F. 
 The ampliti~des of the target echo signals are essentially  tlic srirllc fro111 each antenna hcani, but the phases are different.  .I'lie ~neasurerrierit of arigle of arrival by comparison of the phase relationships in the  sigrlnls frotri the separated antennas of a radio interferometer has been widely used by the  rnciio astronotners for precise nleasilrernerlts of the positions of radio stars. The interferometer  as used by the radio astronomer is a passive instrument, the source of energy being radiated  by tile target itself. 
 Both the Cartesian/Earth-centered Kalman filters involve nonlinear transfor - mations resulting in an imperfect calculation of the tracking accuracy. When prediction  times are long and/or when very accurate results are needed, these imperfections in  the Kalman filter covariance calculation can be significant, and the tracking errors can  be quite non-gaussian. Particle filters typically propagate a large number of random  samples (particles) from a state transition prior distribution to estimate posterior dis - tributions that are not required to be gaussian in form. 
 If a large signal is present such  as at A in Fig. 2.l, it is greater than the surrounding noise peaks and can be recognized on the  basis of its amplitude. Thus, if the threshold level were set sufficiently high, the envelope would  not generally exceed. 
 THE 
 MADE SYSTEMS 4HERE ARE SIGNIFICANT DIFFERENCES  HOWEVER  IN THE REQUIREMENTS FOR A 643 RADAR  COMPARED TO A SHIPBORNE SYSTEM 4HE 643 ANTENNA IS MOUNTED ON A STATIC PLATFORM 4HIS MEANS THAT THE VERTICAL PATTERN CAN BE MORE OPTIMALLY SHAPED !LSO  SINCE THE DESIGN DOES NOT HAVE TO COPE WITH THE SHOCK  VIBRATION AND INSTABILITY EXPERIENCED ON SHIPS RADAR MASTS  LARGER ANTENNAS BECOME FEASIBLE 4HIS ALLOWS AZIMUTH BEAMWIDTHS TO BE NARROWER  THEREFORE  REDUCING THE SIZE OF CLUTTER CELLS 4HE REQUIRED COASTAL AREA TO BE COVERED CAN BE LARGE  AND GETTING THE BEST RANGE OUT OF A FEW RADAR HEADS SITUATED ON TALL TOWERS IS OFTEN MORE COST EFFECTIVE THAN UTILIZING MANY SMALLER INSTALLATIONS "ECAUSE 643 OFTEN FORMS PART OF A NATIONS SECURITY NETWORK  THEN A LONGER RANGE CAPABILITY THAN THAT JUST REQUIRED FOR PORT OPERATIONS MAY BE NECESSARY 4HIS IMPLIES THAT VERY HIGH ANTENNA TOWERS ARE OFTEN NEEDED  IN SOME CASES UP TO  METERS 4HIS EXACERBATES VERTICAL LOBING EFFECTS  WHICH MAY NEED TO BE REDUC ED BY THE USE OF VERTI 
 The distance vector from the radio telescope placed in the origin of the 3D observation coordinate system Oxyz to the g-th generic point of the object space, measured at the p-th moment is described by the vector equation Rg(p)= R0/prime(p)+ AR g (1) where R0/prime(p)= R0/prime(0)+ VTp·pis the mass center position vector; Rg(p)=⎭bracketleftBig xg(p),yg(p),zg(p)⎭bracketrightBigTis the generic point’s distance vector; xg(p),yg(p), and zg(p)are the current coordinates of the generic point, p=0,N−1;Nthe number and full number of emitted pulses, respectively, during time of observation (aperture synthesis); R0/prime(0)= [x0/prime(0),y0/prime(0),z0/prime(0)]Tis the line-of-sight vector of the object’s geometric center at the moment p=0;V=[Vcosα,Vcosβ,Vcosδ]Tis the object’s linear 106. Sensors 2019 ,19, 3344 vector velocity; Rg=⎭bracketleftBig Xg,Yg,Zg⎭bracketrightBigTis the distance vector to the g-th generic point in the coordinate system O/primeXYZ ;Xg=gX·(ΔX),Yg=gY·(ΔY), and Zg=gZ·(ΔZ)are the discrete coordinates of the g-th generic point in the coordinate system O/primeXYZ ;gX,gY,gZare the coordinate indexes of the generic point; ΔX,ΔY, andΔZare the spatial dimensions of the 3D grid cell; cosα,cosβ, and cosγ=mod⎭parenleftBig⎭radicalbig 1−cos2α−cos2β⎭parenrightBig are the guiding cosines; and Vis the module of the linear velocity vector. The elements of transformation-rotation matrix A are deﬁned by Euler’s expressions a11=cosψcosϕ−sinψcosθsinϕ; a12=cosψsinϕ+sinψcosθcosϕ; a13=sinψsinθ; a21=−sinψcosϕ−cosψcosθsinϕ; a22=−sinψsinϕ+cosψcosθcosϕ; a23=cosψsinθ; a31=sinθsinϕ; a32=−sinθcosϕ; a33=cosθ.(2) where in case of a rotating object, ψ,ϕ, andθare time dependent angles, yaw, pitch and roll, respectively. 
 PLUS 
 The term anomalous, or nonstandard, propagation  applies to any of the above propagation conditions other than normal; but it is almost always  used to describe those conditions where the radar range is extended well beyond normal.  A superrefracting duct which lies close to the ground is called a ground-based duct, or a  surface duct. Over water the surface duct is also called the evaporation duct, since it is the result  of water vapor evaporated from the sea. 
 10.2.  The detectability of a target echo on a CRT display depends on such factors as the size  and brightness of the CRT spot, the noise background, pulse repetition frequency, antenna  rotation rate, type of phosphor, and its decay characteristics, the size of the display, and the  color and intensity of the ambient illumination. The effect of most of these factors has been  determined empiri~ally.~'.~'.~~ The name pipology is sometimes applied to the art of designing  and operating the radar display so as to optimize the operator's ability to detect target pips. 
 11.5). 11.6. Duplexing and TR Switches.-As was explained inSec. 
 Slow-wave structures for high-power TWTs include helix-derived structures (contrawound helix, or ring-bar circuit) and coupled-cavity circuits, of which the cloverleaf is one example, and the ladder network.30 Below 100 kW, ring-bar cir- cuits usually have broader bandwidth and higher efficiency than coupled-cavity circuits. Above 200 kW or even below that if average power is a limitation, coupled-cavity circuits dominate.31 If a TWT using a coupled-cavity circuit is cathode-pulsed, there is an instant during the rise and fall of voltage when the beam velocity becomes synchronous with the cutoff frequency (TT mode) of the RF circuit, and the tube usually oscil- lates. These oscillations at the leading and trailing edges of the RF output pulse have a characteristic appearance that has given them the name rabbit ears, as shown in Fig. 
 BASED SCATTEROM 
 % 53 !IR 2OUTE 3URVEILLANCE 2ADAR  LOCATED AT #ANTON  -ICHIGAN 4HE TARGET OF INTEREST IS A SMALL PRIVATE AIRCRAFT !S THE PERSONAL COMPUTER VERSION OF !2%03 DEVELOPED  IT ALSO TRANSITIONED INTO AN  APPLICATION CALLED THE .AVAL )NTEGRATED 4ACTICAL %NVIRONMENTAL 3UBSYSTEM .)4%3   A  SEGMENT OF THE 'LOBAL #OMMAND AND #ONTROL 3YSTEM  
 TION TO THE KEY PARAMETERS MAY BE HELPFUL 4HE NATURAL STARTING POINT IS THE RANGE EQUATION  FROM WHICH SEVERAL PROPERTIES  EMERGE THAT ARE UNIQUE TO THE SPHERICAL GEOMETRY OF RADARS IN ORBIT )N THE NARROW 
 Therefore the theory of Fourier transforms can be applied to the  calculation of the radiation or field-intensity patterns if the aperture distribution is known.  The Fourier transform of a function f (t) is defined as  F(/) = I * ~(1) exp (-j27c~) dr (7.12)  .-m  and the inverse Fourier transform is  The limits of Eq. (7.10) can be extended over the infinite interval from - oo to + oo since the  aperture distribution is zero beyond z = +a/2. 
 RATE FALSE TARGET 4HE JOINT EFFECT OF PHASE AND DELAY QUANTIZATION IN $2&- CAN BE ANALYZED AS REPORTED IN 'RECO  'INI  AND &ARINA  /THER ARTIFACTS IN THE DECEPTION SIGNALS CAN BE INTRODUCED BY IMPERFECTIONS  IN THE DOWN 
  D"  "ECAUSE THESE ABSORBERS DO NOT RELY ON THE CANCELLATION OF A FRONT 
 The tracker simply places its beam at the location where the tar- get is expected, corrects for the pointing error by converting error voltages (with a known angle error sensitivity) to units of angle, and moves to the next target. The system determines where the target was and, from calculations of target velocity and acceleration, predicts where it should be the next time the beam looks at the target. The lag error in this case is dependent on many fac- tors, including the accuracy of the value of angle sensitivity used to convert error voltages to angular error, the size of the previous tracking error, and the time interval between looks.CROSSOVERSECONDSERROR (LAG) . 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar.  TRACKING RADAR  9.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 voltage proportional to the magnitude of the Σ signal or Σ for the AGC of all three IF  amplifier channels. 
 DEMv PHASING SO THAT THE MEASUREMENTS OF THE TWO ALTIMETERS COULD BE CROSS 
 (7) 121. Sensors 2019 ,19, 252 In particular, it can be noticed from the previous formula that, for a MIMO array, small errors produce strong sidelobes in the correspondence of transmitting and receiving grating lobes. To compensate this undesired effect, an efﬁcient and reliable calibration procedure should be applied on the MIMO system. 
 4.22 Phased Arrays  ...................................................  4.23  4.6 Transmitter Stability Requirem ents  ........................  4.25  Pulsed MTI Systems  .......................................... 
 Electronics. vol. 39. 
 It is advantageous for information gathering as in high-resolution radar because of the wide bandwidth that makes it possible to generate short pulses (or wideband pulse compression) and the narrow beam widths that can be obtained with relatively small-size antennas. An X-band radar may be small enough to hold in one's hand or as large as the MIT Lincoln Laboratory Haystack Hill radar with its 120-ft-diameter antenna and average radiated power of about 500 kW. Rain, however, can be debili- tating to X-band radar. 
 6 PLANE FROM THE REGION OF THE  BREAKDOWN VOLTAGE TO THE  REGION OF THE KNEE VOLTAGE  AS SHOWN  IN &IGURE  4HE ABILITY OF A TRANSISTOR TO DEMONSTRATE GAIN AT HIGH FREQUENCIES IS IMPACTED BY THE MOBILITY AND SATURATED VELOCITY OF CHARGE CARRIERS IN THE SEMICONDUC 
 Focusing action is a result of the difference in the velocity of  propagation inside the dielectric as compared with the velocity of propagation in air. The  index of refraction q of a dielectric is defined as the speed of light in free space to the speed of  light in the dielectric medium. It is equal to the square root of the dielectric constant. 
 SPLITTING PROCEDURE IS ABOUT  PERCENT GREATER THAN THE OPTIMAL ESTIMATE &OR LARGE SIGNAL 
 The ambiguity diagram may be used to determine the ability of a waveform to reject  clutter by superimposing on the TR, fd plane the regions where clutter is found. If the trans­ mitted waveform is to have good clutter-rejection properties the ambiguity function should  have little or no response in the regions of clutter.  The problem of synthesizing optimum waveforms based on a desired amb~uity diagram  specified by operational requirements is a difficult one. 
    AND IN THE !.401 
 In addition, better velocity response can be obtained at some  dopplers than either pulse interval will give on a scan-to-scan basis. This is so  because pulse-to-pulse staggering produces doppler components in the passband  of the MTI filter. Pulse-to-pulse staggering may degrade the improvement factor  attainable, as shown in Figure 2.23 and Figure 2.24, but this degradation may not be  significant, or it can be eliminated by the use of time-varying weights as described  below. 
 It is also proportional to. the receiver noise-figure.  The sensitivity of a radar may be visually displayed by using the measurement of receiver  noise to display the normal range rings on the PPI only within the range at which the radar  can detect targets reliably. 
 In this paper, viscosity is treated as the parameter that reﬂects the internal friction property of soil mass and its abilityto resist deformation. The higher the value of the viscosity, the greater the friction resistance between the soil mass is and, thus, less strain and deformation. This is the key reason why the areas with low deformation showed a higher magnitude of elastic modulus and viscosity. 
   -%4%/2/,/')#!, 2!$!2   £°Îx PROVIDE A SHARED INFRASTRUCTURE FOR THE #!3! RADARS 4HIS RADAR SYSTEM WILL INCLUDE  INTELLIGENT DECISION MAKING FOR SCANNING AND TRACKING IMPORTANT LOW 
 no.155. 45.Ridenour, L.N.:"Radar System Engineering," MITRadiation Laboratory Series,McGraw-Hili BookCompany, NewYork,1947,sec.(6.11). 46.Westinghouse Brochure: TheARSR-3 Story,nodate. 
 L. R. Rabiner et al., “Terminology in digital signal processing,” IEEE Trans. 
 ING SINUSOIDAL SIGNAL VALUE TO THE DIGITAL 
 The niajor areas of radar application, in no particular order of  irnpo~ ta~icc, are Ijriefly described below.  Air. Trclffic Corrtrol (A TC). 
 SHAPED SPECTRUM  VAR}  F4444. 3. 34F 
 The doppler frequency is extracted  by the low-pass filter.  Since the total energy contained in the beat-frequency signal is distributed among all tiit:  harmonics, extracting but one component wastes signal energy contained in the other bar-  monies and results in a loss of signal as compared with an ideal CW radar. However, the  signal-to-noise ratio is generally superior in the FM radar designed to operate with the ttrh  Circulator Directional  frequency  multiplier coupler - --------  1 4  Figure 3.17 Sinusoidally modulated FM-CW radar extracting the third harmonic (J, Resst.1 componznt). 
 When in lock –follow mode, the scanner could beAirborne Maritime Surveillance Radar, Volume 1 4-8. driven to track a target in azimuth. The re ﬂector and rotating mechanism were largely unchanged but the waveguide feed was divided between two adjacent feed horns. 
 13.1, the rms waveheight is given approximately by /irms = 0.005(/2 m (13.6) The rms waveheight contains contributions from all the waves on the surface, but very often it is the peak-to-trough height for the higher waves that is of major interest. This is certainly the case for a ship in a seaway or in the shadowing of the surface at low radar grazing angles. The significant height, or height of the . 
 Sci. T otal Environ. 2016 ,544, 744–753. 
 48 HOW RADAR WORKS  working below ro centimetres we have to discard these  initial amplifiers. Ofcourse, as we shall see in due  course, a number of tricks, strange devices, and novel  valves are used even in radar systems of the more con-  ventional wavelengths (around 2-10 metres), and the  newcomer, on making a close inspection of the whole  receiver, may be puzzled at circuit values. But on the  whole the arrangement is normal, and the layman is apt  to marvel at the comparative simplicity, or at least  conventionality, of these radar receivers. 
 NAL PROCESSOR 4ABLE  SHOWS A CATEGORIZATION OF SOME %##- TECHNIQUES ALONG WITH THE %#- TECHNIQUES THAT ARE USED TO COUNTER   3UITABLE BLENDING OF THESE  %##- TECHNIQUES CAN BE IMPLEMENTED IN THE VARIOUS TYPES OF RADARS  AS DISCUSSED IN 3ECTION  4HE ENSUING DESCRIPTION IS LIMITED TO THE MAJOR %##- TECHNIQUES THE READER SHOULD  BE AWARE THAT AN ALPHABETICALLY LISTED COLLECTION OF  %##- TECHNIQUES AND AN ENCY 
 It acts as a Jigital phase shifter if the <.!rive currents are digital. A digital-to-analog conversion  is required to translate the digital control-signal generated by the array computer to a form  that can set the llux-<lrivc phase shifter. The length of the toroid is generally made 15 to 20  percent greater than normal to allow for some shrinkage of the total available increment of  magnetization due to temperature changes. 
 55.Stark.L.:AHelicalLineScanner forBeamSteering aLinearArray,IRETrans.,vol.AP-5. pp.211-216. April.1957. 
 414–421, July 1963.  5. C. 
 Moving targetindication (MTI)radarcanprovidesomeimprovement inthedetection ofmovingtargetsinprecipitation iftheMTIisproperly designed toattenuate thedoppler­ shiftedprecipitation echoes.Unlikelandclutter,stormcloudsarenotstationary andusually haveanonzero relativevelocitythatresultsinadoppler-frequency shift.Theinternalmotions ofthestormcanalsowidenthespectrum oftheprecipitation clutter.Atthehighermicrowave frequencies, whereprecipitation canbeabother,itisdifficulttoachieveeffective MTIbecause ofthereduced blindspeeds(Sec.4.2)andtheincreased spreadoftheclutterspectrum. The Moving TargetDetector, described inSec.4.7,isanexample ofanMTIradardesigned specifically tocopewiththespecialproblems ofprecipitation clutter. Polarization. 
 One of the functions of the servo system is to reduce the  178INTRODUCTION TORADAR SYSTEMS (a) (d)(b) (e) Figure5.18Examples ofacquisition searchpatterns. (a)Traceofhelical scanning beam;(b)Palmerscan;(c) spiralscan;(d)raster,orTV,scan; (e)nodding scan.Therasterscanis sometimes calledann-barscan,where (e) nisthenumber ofhorizontal rows. " scan.Becauseofthisproperty, thePalmerscanissometimes usedwithconical-scan tracking radarswhichmustoperatewithasearchaswellasatrackmodesincethesamemechanisms usedtoproduce conicalscanning canalsobeusedforPalmerscanr.ing.60Someconical-scan tracking radarsincrease thesquintangleduringsearchinordertoreducethetimerequired to scanagivenvolume. 
 Interferometric SAR (InSAR, sometimes also called  “IFSAR”) refers to the use of two antennas whose signals are combined coherently.  InSAR was originally developed by the Jet Propulsion Laboratory (JPL) to detect  ocean currents or moving targets.18,19 The two antennas were displaced horizontally  on the platform (along a line parallel to the ground) so that the received echoes from  a moving target would be different from the corresponding echoes from fixed tar - gets, and thus movers could be detected and analyzed. Later researchers (e.g., Adams  et al.20) used two antennas displaced vertically on the platform so that the received  echoes from a target above the surface (assumed flat) would be different from the  corresponding echoes from a target on the surface, and thus target height could be esti - mated. 
 The full potentialities ofthese tremendous corner reflectors are never realized inpractice because of the strict tolerances imposed bythe short wavelengths ofmicrowave radar. Insufficient flatness inthe walls makes ahuge, imperfect corner reflector behave like one which issmaller but perfect. Inadequate perpendicularity results inseveral return beams inthe vicinity ofthe aircraft instead ofasingle return beam pointed directly atthe aircraft. 
 The radar echo from aircraft is modulated by the rotating propellers of  piston engines, and by the rotating compressor and turbine blades of jet engines.45 (The  compressor would be seen by a radar looking into the forward part of the jet aircraft and the  turbine when looking into the rear.) The characteristic modulations of the radar echoes from  aircraft can, in some cases, be used to recognize one type of aircraft from another; or more  correctly, one type of aircraft engine from another. Aircraft jet-engine modulations are likely  to be of relatively high frequency (ten to twenty kilohertz perhaps) because of the high speed of  the engine components that cause the modulated echo. The helicopter with its large rotating  blades also provides a distinctive modulation of the radar echo that distinguishes it from thc  echoes of otber aircraft. 
  AIRCRAFT  AND A 7 
 BASED  8 
 Ontheotherhand,thetotal reflecting surfaceisincreased bythepresence ofice,reducing thetransmission through the mesh.Therelativeimportance ofthesetwoeffectsdetermines whetherthere isanetincreaseor anetdecrease intransmission. Inunfavorable cases,evenstrongly relkcting meshescanJose theirreflecting properties almostcompletely. Cassegrain antenna.19-23Thisisanadaptation tothemicrowave regionofanopticaltechnique invented intheseventeenth centurybyWilliam Cassegrain, acontemporary ofIsaacNewton. 
 It senses the magnitude of the radar echoes from noise or clutter in the near vicinity of the target and uses this information to establish a threshold so that the noise or clutter echoes are rejected at the threshold and not confused as targets by the automatic tracker. Unfortunately, CFAR reduces the probability of detection. It also results in a loss in signal-to-noise ratio, and it degrades the range resolution. 
 The process contains four steps and is described in Figure 4. First, the images of targets are extracted and the aspect entropy of the pixels is obtained. Second, the binary image is obtained by thresholding. 
 The difficulty isnot ingetting the heat through the actual metal wall. Ashort com- putation shows that adifferential ofafraction ofadegree issufficient for this. Almost allofthe temperature drop occurs across the dead-air films onthe two sides ofthe wall. 
 Soc. Civ.  Eng., 1974, pp. 
 Radar Conf ., 1980, pp. 106–112. ch20.indd   83 12/20/07   1:17:25 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 85-173, National Telecommunications and Information Administration,  April 1985. 107. D. 
 To reduce the effect of speckle and make a more "filled-in" image, the  same scene can be viewed from different aspects or at different frequencies, or both, and the  several images superimposed. The multiple looks can be obtained as in the searchlight mode  by dwelling with a positionable antenna on the same area. Another approach, applicable with a  fixed antenna, is to not use the full synthetic antenna length Le to achieve a resolution Jcr, but  to break up the synthetic length into m subsections and look at the scene from slightly different  aspects each with a resolution m c:5cr .. 
 Later theoretical work for surfaces involves solving integral equations for the scat - tered fields.76 This has been used both to validate other models and to better describe  the true scattering from a known rough surface. This method tends to be computation - ally extensive. Numerical scattering computations are also in vogue.77 Regardless of the model used and the approach applied to determining the field  strength, theoretical work only guides understanding. 
 Skolnik  McGRAW-HILL BOOK COMPANY  Auckland Bogotii Guatemala Hamburg Lisbon  London Madrid Mexico New Delhi Panama Paris  San Juan S5o Paulo Singapore Sydney Tokyo  INTRODUCTION TO RADAR SYSTEMS SecondEdition MerrillI.Skolnik McGRAW-HILL BOOKCOMPANY Auckland Bogota Guatemala Hamburg Lisbon London Madrid Mexico NewDelhiPanama Paris SanJuanSaoPauloSingapore Sydney Tokyo. INTRODUCTION TO RADAR SYSTEMS  International Edition 1981  Exclusive rights by McGraw-Hill Book Co.-- Singapore for  manufacture and export. This book cannot be re-exported  from the country to which it is consigned by McGraw-Hill. 
 The positive doppler resonant wave peak is about 20 dB larger  than the negative doppler peak, indicating a sea driven by winds blowing toward  the radar. The processing used in developing these displays was 200-s CIT and   30-min averaging. Performance Modeling. 
 SOURCE PRIMARY FEED !N EXAMPLE FROM %ASAT !NTENNAS IS ILLUSTRATED IN &IGURE  4HIS IS A  METER REFLECTOR ANTENNA WITH A  DB GAIN AT  '(Z )T HAS AN INVERSE COSECANT 
 H. M. Finn and R. 
 [ CrossRef ] c/circlecopyrt2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). 
 Meanwhile, sample the produced sequence with the interval of dfor ensuring the mutual independence of elements in chaos sequence: zk=xg+kd,k=0, 1, 2,···,N−1 (33) After obtaining the output sequence zkof Formula (33), directly divide the zkinto N/prime=N/U with equal interval. Select the corresponding position of maximum value in various intervals, and assign 1 to corresponding position of Φr, and others a zero: Φr=⎡ ⎢⎢⎢⎢⎢⎢⎣1,···,0 ,···,0/bracehtipupleft/bracehtipdownright/bracehtipdownleft/bracehtipupright U0··· 0 ......··· ··· 00 ··· 0,···,0 ,···,1/bracehtipupleft/bracehtipdownright/bracehtipdownleft/bracehtipupright U⎤ ⎥⎥⎥⎥⎥⎥⎦, (34) where, each row has a (0, 1)random sequence with length of U, and value 1 is at the position of the maximum value in the corresponding interval of the chaos sequence produced in {1, 2,···,U}, and others are zero. In practical applications, adopt parallelization to transmit N/primerandom single frequency signal, and its data rate is N/prime/T. 
 In some applications, the pitch is small so ,that little harm results from omitting the  stabilization of the pitch axis, leaving only the roll axis stabilized. This results in a simpler  system compared to providing a stable base. This is called roll stabilization. 
 of ttie clutter spectrum is a: = af + a;,, the MTI improve-  ment factor for the total clutter spectrum is  'The solid curves of Fig. 4.35 plot this equation for a three-pulse delay-line canceller (N, = 2).  If the widening ofthe spectrum is a result of the radar platform's velocity, its effects can be  mitigated by making the radar antenna appear stationary. 
 9. J. Ruze, “Antenna tolerance theory—A review,” Proc. 
  
 The PLSR along the range direction shown in Figure 13bi s−13.2299. The ISLR along the range direction is −9.8458. The PLSR along the azimuth direction shown in Figure 13bi s−13.2536. 
 Aradomepermitsaground-based radarantenna tooperateinthepresence ofhighwinds. Italsoprevents iceformation ontheantenna. Although itispossible todesignantennas strong cnoughtosurviveextreme weather conditions andtoprovide sufficiently largemotorsto rotatetheminhighwinds,itisoftenmoreeconomical todesignlighterantennas withmodest drivepowerandoperatetheminsideradomes. 
 PRINTED POWER DIVIDERS 4HE ARRAYS ARE USUALLY TWO 
 J. Syst. Eng. 
 COUNTERMEASURES v SHORT LECTURE NOTES   'EORGIA )NSTITUTE OF 4ECHNOLOGY    , " 6AN "RUNT   !PPLIED %#-  VOL   $UNN ,ORING  6! %7 %NGINEERING  )NC    0 * 'ROS  $ # 3AMMONS  AND ! # #RUCE  h%##- !DVANCED 2ADAR 4EST "ED %!24"   SYSTEMS DEFINITION v  )%%% .AT !EROSP %LECTRON #ONF .!%#/.    -AY n      PP n  - ! *OHNSON AND $ # 3TONER  h%##- FROM THE RADAR DESIGNERS VIEW POINT v  -ICROWAVE *   VOL   PP n  -ARCH   ( % 3CHRANK  h,OW SIDELOBES PHASED 
 1941.  8. Domh. 
 21.3 MODELING Models of the GPR situation range from a simple single frequency evaluation of  path losses to complete 3D time-domain descriptions of the GPR and its environ - ment. Modeling techniques include single frequency models, time-domain models,  ray tracing, integral techniques, method of moments (MoM), and discrete element  methods. The Finite-Difference Time-Domain (FDTD) technique has become one of  the popular techniques and can be developed to run on most desktop computers with  relative efficiency. 
 Figure 2.49 shows the filter response if the transmitter starts radiating just as a null of  the antenna pattern passes the point of clutter. The individual samples of residue are  60 or more dB below the peak clutter return. The improvement factor for this sequence  is 57 dB. 
 DEFENSE SCENARIO &OR A PRACTICAL EXAMPLE OF DUCTING EFFECTS  ONE CAN READ ABOUT THE h"ATTLE OF THE  0IPSv   $URING THE SUMMER OF   TWO 53 .AVY TASK GROUPS WERE DEPLOYED TO  REMOVE THE *APANESE OCCUPATION OF !TTU  !LASKA /N THE NIGHT OF *ULY TH  THE 533 -ISSISSIPPI GAINED RADAR CONTACT WITH WHAT WAS BELIEVED TO BE *APANESE FLEET UNITS MOV 
 In the aututnrl of 1922 A. ti. I'aylor arid L. 
 Through  a closed loop, which includes a smoothing time constant, the error signal controls  a phase shifter at the coho output such that the doppler shift from pulse to pulse is  removed. It should be noted that since the first sweep entering the MTI is taken as a  reference, any phase shift run-out as a function of range will increase proportionally  to the number of sweeps. Ultimately this run-out will exceed the speed of response  of the closed loop, and the MTI must be reset. 
 ,/" ÊÊ   Ê1* " 6 
 FEEDBACK CURVES SHOWN IN &IGURE  ARE ALMOST INDISTINGUISHABLE FROM  THE THEORETICAL CURVES DERIVED FOR A GAUSSIAN PATTERN SHOWN IN &IGURE  /NE OF THE CURVES SHOWING THE EFFECT OF FEEDBACK ON THE TRIPLE CANCELER IS NOT STRAIGHT BECAUSE TWO OF THE THREE ZEROS ARE NOT AT THE ORIGIN BUT HAVE BEEN MOVED ALONG THE UNIT CIRCLE THE OPTIMUM AMOUNT FOR  HITS PER BEAMWIDTH 4HUS  AT  HITS PER BEAMWIDTH  THESE TWO ZEROS ARE TOO FAR REMOVED FROM THE ORIGIN TO BE VERY EFFECTIVE  &)'52%  )MPROVEMENT FACTOR LIMITATION DUE TO SCANNING FOR CANCELERS WITH FEEDBACK . 
 TIES n ! BLEND OF MEDIUM AND HIGH 02&  KNOWN AS HIGH 
 2015 ,193, 243–255. [ CrossRef ] 5. Zhou, L.; Guo, J.M.; Hu, J.Y.; Li, J.W.; Xu, Y.F.; Pan, Y.J.; Shi, M. 
 mercury. Thus, bythe choice of de carrier frequency and tube diameter, Ftc+. 16.34.—A reflecting endcellforaitispossible toreduce theamplitude mercury line.ofunwanted echoes tolessthan 1per cent ofthedesired signals. 
 NOISE RATIO IN RANGE 
 28, pp. 224–240, 1990. 87. 
 The mission profile begins with a takeoff, con - tinues through flight to a target, and ultimately returns to the starting point. Along the  way, the aircraft uses a variety of modes to navigate, search and acquire targets, track  targets, deliver weapons, assess battle damage, engage in countermeasures, and moni - tor and calibrate its performance. AESAs have demonstrated simultaneous multiple  weapon deliveries.22 ch05.indd   10 12/17/07   1:26:41 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Amosaic ofmicrowave-sensitive elements located atthefocal surface ofareceiving antenna would bescanned byan. 122 LIMITATIONS OF PC’LSE RADAR [SEC. 42 electron beam. 
 In this stage, we generate a combined change map and separate it into two change maps. In order to generate the combined change map, we used an approach similar to that was used in [ 13]. In the original approach, an eigenvector 268. 
 Normalizing, to give unity am- plitude when 0 = 0, and simplifying give E0(Q) = cos TT -sin 0 (7.1)LA. J The absolute value of E0 (0) is plotted in Fig. 7.4 as a function of ir(s/X) sin 0. 
 pp. 790 803. August, 1956. 
 This factor should double themaximum range ofdetection, compared tofree- space conditions. Something like this increase isactually observed, although itshould not inevery case betaken forgranted, inview ofthe idealized model upon which itisbased. “Low coverage” refers toasituation inwhich the target lies well below thelowest maximum inFig. 
 5. Emerson, R. C.: Some Pulsed Doppler MTI and AMTI Techniques, RAND Corp. 
  IN DECIBELS   6J 6% TJ % T)1 D D           ¤ ¦¥³ µ´ COS      SIN  VV$$%%E %EJT JTDDVV 
 The sweep voltage isgenerated bythe884 thyratron operating asarelaxation oscillator. When the discriminator crossover point is reached, positive pulses from thevideo amplifier VI1firethegastube VIZ, thus stopping thesweep. Toobtain the control pulses avery small part ofthetransmitter r-f power ismixed with aportion ofthelocal-oscillator output signal inthe .4FC crystal. 
 FORMLY ESTABLISHED IN THE LITERATURE 4ERMS SUCH AS  QUASI 
 BASED RECEIVERS 4HE FIRST ANALYSIS OF THESE DATA GAVE ONE 
 Puckle’s  Time Bases, and the delay-line system is used when it  is required to produce a series of pulses spaced by  definite intervals. In the delay line the number of  sections is arranged to be equal to 1-28 times the total  delay required, divided by the time of rise of the pulse  wave-front. The time required for the burst of energy  to return to the input end of the line is dependent upon  the electrical length of the line. 
 IllA,  pp. 539-544, 1946.  59. 
 32, no. 21,  pp. 58-60, May 22, 1959. 
 SlIhcllltter visihility. Theratiobywhichthetarg~techopowermaybeweakerthanthe coincident clutterechopowerandstillbedetected withspecified detection andfalse­ alarmprohahilities. Alltargetradialvelocities areassumed equallylikely.Asubclutter visibility of,forexample, 30dBimpliesthatamoving targetcanbedetected inthe presence ofcluttereventhoughtheclutterechopoweris1000timesthetargetecho. 
 STATE ANTENNAARRAY 4HE !.&03 
 ENING PROCESS INCREASES THE NUMBER OF INDEPENDENT SAMPLES FOR RANGE AVERAGING THAT ALLOWS IMPROVED PARAMETER ESTIMATION ACCURACY BUT AT A COST OF SIGNIFICANTLY REDUCED 3.2 4HE HIGHER NOISE BANDWIDTH IN THE RECEIVER REQUIRED BY THE HIGHER RATE SAMPLING AND THE WHITENING FILTER NOISE ENHANCEMENT CAUSE THE 3.2 TO BE REDUCED BY A FACTOR OF APPROXIMATELY  ,  WHERE , IS THE INCREASED SAMPLING FACTOR 3TATED ANOTHER WAY  THE  WHITENING FILTER EFFECTIVELY SHORTENS THE TRANSMIT PULSE BY  ,  WHILE PASSING THE INCREASED  RECEIVER NOISE POWER BY  ,  THEREBY TRADING RANGE RESOLUTION FOR 3.2 &ORTUNATELY  FOR  PRECIPITATION ECHOES AND TYPICAL WEATHER RADARS  THE 3.2 IS QUITE HIGH  AND EVEN AFTER THE WHITENING PROCESS  IT REMAINS HIGH ENOUGH TO EFFECTIVELY UTILIZE THE LARGER NUMBER OF INDEPENDENT SAMPLES FOR IMPROVED BASE DATA ESTIMATES OR IMPROVED RANGE RESOLU 
 SAMPLE 
 70. Palmer, D. S., and D. 
 LATOR OR AN AMPLIFIER 4HE OTHER ELECTRONIC TUBES MENTIONED IN THIS CHAPTER ARE USUALLY OPERATED AS AMPLIFIERS !MPLIFIERS AT MICROWAVE FREQUENCIES HAVE GENERALLY PRODUCED HIGHER POWERS THAN OSCILLATORS BUT  PROBABLY MORE IMPORTANT  THEY ALLOW THE USE OF STABLE  MODULATED WAVEFORMS NEEDED FOR WAVEFORMS IN RADARS THAT DEPEND ON THE USE OF PULSE COMPRESSION AND FOR THE DOPPLER EFFECT TO DETECT MOVING TARGETS IN CLUTTER 4HE MICROWAVE  KLYSTRON AMPLIFIER WAS INVENTED BEFORE THE MAGNETRON AND WAS  DESCRIBED IN A PAPER IN THE -AY  ISSUE OF THE  *OURNAL OF !PPLIED 0HYSICS    &OR THE MOST PART  THE KLYSTRON AMPLIFIER WAS IGNORED DURING 77)) AND DIDNT ATTRACT     )N THE 5NITED 3TATES  THE DEVICE THAT GENERATES THE 2& POWER IS CALLED A  TUBE  BUT IN THE 5NITED +INGDOM  IT IS CALLED  A VALVE ! BOOK ON MICROWAVE POWER SOURCES SUGGESTS THAT THESE DEVICES BE CALLED  MICROWAVE VACUUM ELECTRONIC  DEVICES -6%$  )N THIS CHAPTER  HOWEVER  THE NAME TUBE WILL BE RETAINED. 
 EXCITER STABILITY HOWEVER  WHEN EVALUATING THE OVERALL PERFORMANCE  OTHER CONTRIBUTIONS SHOULD NOT BE NEGLECTED !DVANCES IN STATE 
 and(4)onedB forscanning degradation. thenthesidelobe levelduetothequantization canbeexpressed as rmssidelobe level~-li-­2 N \vhereN=totalnumberofelements inthearray.Foranarraywithfourthousand elements. a three-hit phnseshifterwillgiverrnssidelobes betterthan47dBbelowthemainbeam.anda four-hit phaseshiftergives53dBsidelobes. 
 Any one or a number of transmitting-tube types might be used as the power amplifier.  These include the triode. tetrode, klystron, traveling~wave tube, and the crossed-field amplifier. 
 4. Sun, G.; Xing, M.; Xia, X.; Yang, J.; Wu, Y.; Bao, Z. A Uniﬁed Focusing Algorithm for Several Modes of SAR Based on FrFT. 
 The outputs ofthe radar and AFC crystals goindouble-shielded cables tothe receiver and AFC chassis respectively. The AFC control circuit isessentially oftheform described inSec. 12.7. 
 S., S. Hershenov, and E. F. 
 Wehave already remarked that pulser internal impedance may some- times play adeciding role inmode stability. Itisalso true that thepower supply steady-state V-Icharacteristic may influence magnetron behavior. L---I .—.—. 
 5.  69. King, R. 
 FORMING NETWORK !CTIVE ARRAY ANTENNAS INCLUDE LOW 
 K. S.: Uesignirlg Dielectric Microwave Lenses, Electronics, vol. 29, pp. 
 In the second pe- riod, the transmitter frequency is varied linearly at a rate/ in one direction. Dur- ing the round-trip time to the target, the local oscillator has changed frequency so that the target return has a frequency shift, in addition to the doppler shift, that is proportional to range. The difference in the frequency A/of the target return in the two periods is found, and the target range calculated from R= ^l (17.11)2/1 The problem with only two FM segments during a dwell time is that, with more than a single target in the antenna beamwidth, range ghosts result. 
 ÊÊ /"Ê "6 Ê/, 
 MARIZES BISTATIC RADAR APPLICATIONS IN THESE OPERATING REGIONS  %NTRIES IN THE DEDICATED TRANSMITTERCO 
 Rept. 424, pt. III, October 1966. 
 Squadrons were instructed to submit regular reports of the performance of ASV Mk. I, some of which are recorded in an RAF ﬁle [5]. Squadron reports at the end of February 1940 showed the development of its use for reconnaissance andescort duties [ 2,5]: Reconnaissance : ASV is of great assistance at night and in bad visibility. 
  AND 53 -ARINE #ORPS  -#/    ! :ACHEPITSKY  h6(& METRIC BAND  RADARS FROM .IZHNY .OVGOROD 2ESEARCH 2ADIOTECHNICAL  )NSTITUTE v )%%% !%3 3YSTEMS -AGAZINE  VOL   PP n  *UNE    !NONYMOUS  h!7!#3 VS %# BATTLE A STANDOFF v  %7 -AGAZINE  P   -AY*UNE   - 3KOLNIK  $ (EMENWAY  AND * 0 (ANSEN  h2ADAR DETECTION OF GAS SEEPAGE ASSOCIATED WITH OIL  AND GAS DEPOSITS v )%%% 4RANS  VOL '23 
 72. Cheston, T. C.: Microwave Lenses, Srmposi11m on Microwave Optics, McGill University, Montreal. 
 £Î°Îä  2!$!2 (!.$"//+  %FFECT OF %RRORS  7HEN ERRORS OCCUR IN PHASE OR AMPLITUDE  ENERGY IS REMOVED  FROM THE MAIN BEAM AND DISTRIBUTED TO THE SIDELOBES )F THE ERRORS ARE PURELY RANDOM   THEY CREATE RANDOM SIDELOBES THAT ARE CONSIDERED TO BE RADIATED WITH THE GAIN AND PATTERN OF THE ELEMENT 7HEN THE ERRORS ARE CORRELATED  THE SIDELOBE ENERGY WILL BE LUMPED AT DISCRETE LOCATIONS IN THE FAR FIELD 4HE CORRELATED E RRORS WILL  THEREFORE  PRO 
 BODY TARGET  AND THE SHIFTS WILL BE A FUNCTION OF THE DISPLACEMENT OF THE SCATTERER FROM A REFERENCE POINT SUCH AS THE CENTER OF ROTATION OF THE TARGETS RANDOM MOTIONS 4HEREFORE  A HIGH 
 Nevertheless, it may be stated that whenever the a priori  probabilities are known, the inverse-probability method may be used with confidence. When  the a priori probabilities are not known, the likelihood-ratio test is usually employed.  Relationship of inverse probability and likelihood-ratio receivers. 
 Howard, J.E.: A Low Angle Tracking System for Fire Control Radars, IEEE 1975 illlt!rnmivna/  Radar Co1iference, pp. 412-417.  51. 
 According to this, the signal at the receiver must be temporally shortened (i.e. compressed)   when dealing with longer pulses, this in order to improve the range resolution as well as the precision and the sensitivity.  Procedures of this type have been developed in communication theory long before they found use in Radar technology. 
 SYNCHRONOUS ,%/  HAVING  ^n INCLINATION o AND  KM ALTITUDE 3UN 
 Although it  is probably valid outside this size and frequency range, it does not apply to elevation  angles other than grazing incidence. At higher elevation angles, as might be viewed from  aircraft, the cross sections of ships might be considerably less than at grazing incidence,  perhaps by an order of magnitude. When no better information is available, a very rough order  of magnitude estimate of the ship's cross section at other-than-grazing incidence can be had by  taking the ship's displacement in tons to be equal to its cross section in square meters. 
 R., and R. L. Kuehn:" Display Systems Engineering," McGraw-Hill Book Company. 
 C. M .. and E. 
 7 .20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 half with the lower mean value. The first simulation involved two targets separated by  1.5, 2.0, 2.5, or 3.0 range cells and a third target 7.0 range cells from the first target.  When the two closely spaced targets were well separated, either 2.5 or 3.0 range cells  apart, the probability of detecting both targets ( PD2) was < 0.05 for the linear detector  with T A= +ˆ ˆµ σ ; 0.15 < PD2 < 0.75 for the linear detector with T B=ˆµ; and PD2 > 0.9  for the log detector. 
 The half-wave thickness  is nonreflecting if ohmic losses are negligible. The bandwidth of such a radome is limited, as is  the range of incidence angles over which the energy is transmitted with minimal reflection.  The A sandwich is a three-layer wall consisting of a core of low-dielectric-constant mater­ ial with a thickness of approximately one-quarter wavelength. 
 Increased antennaheight as well as increases in frequency tends to lower the lobes of theinterference pattern. The pitch and roll of the ship radiating does not affect the structure of the interference pattern.. 9ATMOSPHERIC FACTORS AFFECTING THE RADAR HORIZON THE RADAR HORIZON The affect of the atmosphere on the horizon is a further factor which should be taken into account when assessing the likelihood of detecting aparticular target and especially where the coastline is expected. 
 Wu, W. G. Stevens, X. 
 Uicaudo, V. J.: Radomes, Cfiap. 14 of" Radar Handbook," M. 
 ORDER APPROXIMATION THEN BECOMES  SP LQ   §©¶¸   0 0F ' 2 D !R TT)LLUMINATED AREEA¯   0ROPER SCATTERING MEASUREMENTS DEMAND AN ACCURATE AND COMPLETE MEASUREMENT OF  ANTENNA GAIN  'T 4HIS CAN BE A VERY TIME 
 This paper deﬁnes the following three global sparsity constraints: (1) when p=1,/bardblg/bardbl1,0=/bardbl(|g1|+|g2|)/bardbl0, is termed as mixed sum norm, i.e., sparsity of amplitude sum of the two ISAR images is taken as the global sparsity constraint; (2) when p=2,/bardblg/bardbl2,0=/bardbl/parenleftBig |g1|2+|g2|2/parenrightBig1/2 /bardbl 0is termed as mixed Euclidean norm; (3) when p=∞,/bardblg/bardbl∞,0=/bardblmax(|g1|,|g2|)/bardbl0is termed as mixed inﬁnite norm, i.e., the sparsity of one of the two ISAR images (with larger amplitude) is taken as the overall sparsity constraint. The mixed sum norm and mixed Euclidean norm are both measured by taking the number of non-zero elements of amplitude sum of images in all channels as the global sparsity. Since the scattering points are aligned at different angles, the additivity is reasonable. 
 BAND DATALINK CHANNEL  EG  *4)$3  TO CARRY '03 POSITION UPDATES  $OPPLER SHIFTING  DUE TO LINK GEOMETRY DYNAMICS MUST BE ACTIVELY COMPENSATED ! RELATED ISSUE IS SYN 
 $ISPLAY  GEOMETRY  FOR  MEASURING HORIZONTAL WIND WITH A SINGLE DOPPLER RADAR  -EASUREMENT OF THE RADIAL VELOCITY FOR A COMPLETE AZIMUTHAL SCAN A  AT ELEVATION ANGLE  @ PERMITS AN ESTIMATE OF THE  VERTICAL PROFILE OF HORIZONTAL WINDS  #OURTESY OF 5NIVERSITY  #ORPORATION FOR !TMOSPHERIC 2ESEARCH Ú   "OULDER  #/   .   -%4%/2/,/')#!, 2!$!2   £°ÎÎ AND TO SUPPRESS GROUND CLUTTER (OWEVER  IT IS KNOWN THAT RADAR BEAM BENDING CAUSED  BY ATMOSPHERIC REFRACTION AND THE RESULTING ANOMALOUSLY PROPAGATED GROUND CLUTTER ECHO GIVES AN INDICATION OF THE VERTICAL PROFILES OF TEMPERATURE AND MOISTURE IN THE INTERVENING LOWER ATMOSPHERE -OREOVER  MEASURING THE PROPAGATION SPEED OF THE RADAR PULSE BETWEEN NORMALLY PROPAGATED CLUTTER TARGETS THOSE DIRECTLY VIEWED BY THE RADAR  GIVES AN ESTIMATE OF THE REFRACTIVE INDEX OF AIR ALONG THIS PROPAGATION PATH "Y MEASURING THE ABSOLUTE PHASE OF THE RADAR SIGNAL RECEIVED FROM STATIONARY GROUND CLUTTER TARGETS AND COMPARING THEM WITH REFERENCE ABSOLUTE PHASE MEASUREMENTS UNDER KNOWN REFRACTIVE CONDITIONS  ONE CAN MEASURE THE NEAR SURFACE PROPAGATION SPEEDS OF THE RADAR PULSE ALONG THESE PATHS 4HEN  THE REFRACTIVE INDEX  OR REFRACTIVITY  OF THE  ATMOSPHERE OF THESE ATMOSPHERIC PATHS MAY BE DETERMINED  2EFRACTIVITY IS A FUNC 
 CROSS RANGE (ARBITRARY UNITS) FIG. 25.6 Bistatic isodoppler contours for two dimensions and a flat earth.90 direction of the receiver. Bistatic cross sections are more complex than monostatic cross sections since &B is a function of aspect angle and bistatic angle. 
 B1–B6 represent six carbonate rock belts aligned in an East-West orientation, namely Tianxingzhou, Daqiao, Baishazhou, Zhuankou, Junshan, and Hannan. 2.2. Datasets We employ 20 descending Radarsat-2 wide ultra-ﬁne (WUF) single-look complex (SLC) images acquired from October 2015 to June 2018 at intervals of 24, 48, 72 or 96 days. 
 Sherman: Pulse Radar for Trajectory lnstrumcnt.:ition, paper prcscnlc<l al  Sixth National Flight Test instrumentation Symposium, Instrument Society of America, San Diego,  Calif .. May 3. 1960. 
 RITE IS LATCHED WITH A PARTICULAR PHASE EG  n  4HE FERRITE MAINTAINS THE PHASE UNTIL A CURRENT PULSE IN THE OPPOSITE DIREC 
 Óä°Èä  2!$!2 (!.$"//+  SPHERICAL ASSUMPTION FROM THE  
 For example, current  swing in an amplifier that is biased Class-A replicates exactly the input signal up  to the point where the transistor voltage and current limits are reached. In practice,  Class-A amplifiers are the most linear as well as the least efficient. High dynamic- range linear receive amplifiers are biased Class-A, and audio amplifiers may be also  be biased Class-A to preserve the linearity of the input signal. 
 The deviator acts asareactance tube, modulating anoscillator which operates atone-eighth thedesired carrier frequency. Three stages offrequency-doubling and power amplification Signals VideoPhasesplitterPush.pull amplifier deviator tt Doubler25Me/seeDoubler12.5Me/see Push.pull oscillator Detector Discriminator anddoubler IPowermonitor ISignalmonitor YTransmitter R.f amplifier Mixer Ifamplifier 1 > DiscriminatorVideo Signals amplifier Receiver FIG. 17.1 S.—100-Mc/sec frequency-modulated equipment. 
 tion near the shadow boundaries is rapid; hence surface contributions there are ignored in a stationary phase evaluation, but an exact evaluation includes them because the shadow boundaries are the limits of integration. Because the actual surface field distributions do not suddenly drop to zero as the shadow boundary is crossed, as assumed by the theory, the shadow boundary contributions are spurious.33'34 Therefore, a stationary phase approximation of the physical optics integral over closed curved surfaces tends to be more reliable than an exact eval- uation. With this in mind, the stationary phase result for a circular cylinder is 0 sin (H sin 6) 2<r = kat2 . 
 (25.23) matches the specular ridge in Fig. 25.10 within 5 dB, for (<JB°)S < 1. In-Plane Sea Clutter Scattering Coefficient. 
  
 Another advantage is the capability to transmit very high peak power  without the limitations of full peak power propagating through a single transmission  line. This is accomplished in the corporate feed array by placing high power amplifiers  where the power divides to the subarrays, allowing the sum of the high peak power  amplifier outputs to add in space to meet requirements for long-range tracking and  power sharing between multiple simultaneous targets. The parallel power amplifier configuration also provides a practical means for  overcoming the narrow instantaneous bandwidth of typical phased arrays at wide  scan angles. 
 Willshaw and L. Rushforth.  ‘Centimetric,’ where radar wavelengths are concerned,  means a range of usually 3 to 10 centimetres, although  systems using even shorter wavelengths are now in use,  and the trend is towards higher frequencies still. 
   #OMPONENT /UTPUT    RD /RDER )NTERCEPTD"M         #OMPONENT /UTPUT D"    #OMPRESSION 0OINTD"M        
 28, pp. 89-106, Aug., 1964.  67. 
 With noise this low relative to the carrier there is no concern that a significant portion of the target's energy will be lost in any practical filtering operation. What is of concern is the energy of the noise components carried into the receiver on the unwanted spillover and clutter signals. Moreover, should vibrations cause varia- tions in the length or lengths of the spillover path the problem is more severe, since such effects introduce spectral lines that may fall directly into the doppler band of interest. 
 POWER WIDTH OF  THE MAINLOBE 7ITH NO WEIGHTING  THE LATTER IS   TIMES TH E VALUES GIVEN ABOVE THUS  THE TWO DEFINITIONS ARE NOT VERY DIFFERENT 7E PREFER THE FORMER DEFINITION BECAUSE  FOR NO WEIGHTING  IT RESULTS IN A SIMPLER FORMULA WITHOUT THE INTRODUCTION OF THE FACTOR OF   -ORE DETAILS CONCERNING WEIGHTING ARE GIVEN IN 3ECTION   4HERE ARE AT LEAST TWO MATHEMATICALLY EQUIVALENT WAYS OF CONSIDERING 3!2 !S WE HAVE  DEVELOPED THE CONCEPT SO FAR  THE CROSSRANGE RESOLUTION MAY BE CONSIDERED TO RESULT FROM THE DOPPLER SHIFTS RESULTING FROM THE DIFFERENT APPARENT LINE 
 Earth Planets Space 2011 ,63, 377–381. [ CrossRef ] 7. Reinisch, B.W.; Huang, X. 
 How- . B/B0pt FIG. 2.1 Bandwidth correction factor CB as a function of bandwidth Bn relative to op- timum bandwidth £opt; plotted from Haeffs empirical formula, Eq. 
 GRAZING THE  SHADOW REGION  #ROSS 
 July25-27.1972.lEE(London) Conference Publication no.87.pp.5.1-59. 25.Valen7uela, G.R..andM.R.Laing:StudyofDopplcr SpectraofRadarSeaEcho.J.Geopllys. Res.. 
 A spike echo can appear without the  presence of a whitecap, but no whitecap is observed in the absence of a spike. The spike echo  at A' band is amplitude modulated with frequencies of the order of 50 HL and with a li~gh  modulation index. The spiky nature of sea echo indicates that the breaking of water waves  plays an important role in producing ba~kscatter.''~  In addition to changes in clutter characteristics with narrow pulse widths, changes are  also noted with narrow beamwidths. 
 (Evenanalogphaseshifters, whicharecontinuously variable. cannotbeconveniently settoaprecisevalueofphasewithout specialcareincalibra­ tionoverthedesiredrangeoftemperature andfrequency.) Figure8.5illustrates theparallel-line configuration ofthedigitally switched phaseshifter inwhichthedesired lengthisobtained bymeansofapairofone-by-N switches. Eachofthe boxeslabeledSrepresents aSPSTswitch.TheNportsofeachone-by-N switchareconnected toNIinesofdirferentlengthsI"12,...,IN.ThenumberofIinesdepends onthedegreeofphase quantization thatcanbetolerated. 
 DELAY RATES  WHETHER DUE TO REAL SCATTERERS OR TO INTERACTIONS BETWEEN SCATTERERS %VEN THOUGH THE CONTRIBUTIONS OF SOME SCATTERING CENTERS MAY INVOLVE PROPAGATION IN DIRECTIONS OTHER THAN ALONG THE LINE OF SIGHT FROM THE RADAR  THE SYSTEM HAS NO WAY OF DISCERNING THAT FACT 4HEREFORE  DESPITE THE POWERFUL DIAGNOSTIC VALUE OF IMAGES LIKE THESE  ONE MUST ALWAYS BE AWARE THAT MULTIPLE INTERACTIONS BETWEEN TARGET ELEMENTS CAN CREATE SCATTERING SOURCES THAT ARE NOT WHERE THEY APPEAR TO BE. £{°ÎÈ  2!$!2 (!.$"//+  £{°xÊ , ,Ê 
 F. Rogers, J. A. 
 This system can be used to measureSCATTERING COEFFICIENT ANTENNA PATTERN VERTICALPOINTINGPOINTINGANGLE ANGLE FROMANTENNA AXIS PRODUCT G2cr°INTEGRAND OF POWER RETURNEDINTEGRAL RETURN THAT WOULD BEMEASURED BY VERY NARROWBEAM RETURN MEASURED BYACTUAL BEAM . surface scattering coefficients when the distance between radar and tar- get is changing, such as with a fixed radar observing the sea or a radar on a helicopter. If the scatterometer is mounted on a boom truck, the range tracker is not needed; but it is con- venient because the range changes as the angle of incidence is changed. 
 56, pp. 1811-1817.  November, 1968. 
 Thepresence oficeonthereflector surface isanimportant consideratio.n forboththe electrical andthemechanical designoftheantenna. Iceaddstotheweightoftheantenna and makesitmoredifficult torotate.Inaddition, iftheiceweretoclosetheholesofamesh antenna sothatasolidratherthananopensurfaceispresented tothewind,biggermotors wouldbeneededtooperatetheantenna. Thestructure alsowouldhavetobestronger. 
 44/74, 12th November 1944 (TNA AIR 65/144) [3] Performance of A.S.V. Mk. VII (X band) in Wellington XIV Aircraft, C.C.D.U. 
 90. L. Phalippou, L. 
 ING BALLISTIC MISSILE REENTRY MEASUREMENT ACCURACY   AND THE COMMERCIAL  "INET )NC   BISTATIC RECEIVER OPERATING WITH MONOSTATIC DOPPLER WEATHER RADARS TO MEASURE THREE 
 13.4.3 This is a composite·  plot of experimental X-band data obtained at three different locations and at three different  times for a grazing angle of 10°. (The data represented by the solid circles were obtained  in the Bermuda area; the x's in the North Atlantic; and the triangles, off .Puerto Rico.)  The dashed curve in each figure is drawn as if all three sets of data were from a single  population. This curve is of the form exp ( -c/ U) where c is an arbitrary constant and U is  the wind speed. 
 Alltheplots observed attheFDP arenot passed totheFCC. Since control executed bytheFDP makes sector control bytheFCC outdated formany operations, itisunimportant toreport allplots. Astudy made atone oftheFDP’s of.X1X TAC from Sept. 
 C. Boesswetter, “ECCM effectiveness of a low sidelobe antenna for SAR ground mapping,”  AGARD A VP Symp. “ Multifunction Radar for Airborne Application s,” Toulouse, 1985. 
 67 The characteristics of the  wideband pulse compression system developed for the Cobra Dane radar are sum - marized in Table 8.9. ch08.indd   35 12/20/07   12:51:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 , vol. 17, pp. 257–277,  2000. 
 The antenna/array shown  in Figure 13.44 is constructed of either 54 (AN/TPS-59), 44 (AN/FPS-117), or 34  (AN/TPS-77) identical horizontal passive row-feed networks, one above another on  6.6-inch centers. Mounted directly behind each row feed is a dedicated row transmit - ter and receiver. The row transmitters and receivers are similar for each row. 
 Even if the solid-state transmitter were lighter than a conventional tube transmitter,  the weight is found at a had place, on the antenna itself. This is especially important for  shipboard application where weight high on the mast must be minimized.  SJ·stem considerations. 
 Units Input STC Attenuator Amplifier Bandpass Filter Mixer Bandpass Filter Amplifier AGC Attenuator Limiter A/D Converter Component    Noise FiguredB 3.0 5.0 0.5 6.5 5.0 4.0 6.0 14.0 Component Gain dB −3.0 12.0 −5.0 −6.5 −0.2 20.0 −6.0 0.0 Component Output    3rd Order InterceptdBm 43.0 32.0 50.0 20.0 50.0 38.0 40.0 30.0 Component Output 1dB    Compression PointdBm 30.0 18.0 40.0 10.0 40.0 23.0 30.0 −1.0 Cumulative Gain dB −3.0 9.0 8.5 2.0 0.0 20.0 14.0 14.0 Cumulative    Noise FiguredB 3.00 8.00 8.01 8.33 9.13 9.86 9.88 10.29 Cumulative Output    3rd Order InterceptdBm 43.0 32.0 31.4 18.8 16.8 34.3 28.1 25.9 Cumulative Output 1dB    Compression Poin tdBm 30.0 18.0 17.5 7.4 5.4 21.0 14.9 −1.1 Receiver Noise Level dBm/Hz −174.0−157.0−157.5−163.7−164.9−144.1−150.1−149.7 System  Noise Level dBm/Hz −149.0 −152.0−139.0−140.4−146.9−148.9−128.9−134.9−134.9 Bandwidth MHz 1000 1000 100 100 10 10 10 10 A/D SNR in    Nyquist BWdB 70.0 A/D Converter    Sample RateMHz 100.0 A/D Full Scale Level dBm −14.0 −17.0 −5.0 −5.5−12.0 −14.0 6.0 0.0 0.0 0.0 A/D Noise Level dBm/Hz −147.0 System Noise Relative    to A/D NoisedB 12.1 Maximum Point Clutter    or Target LeveldBm −20.0 −23.0−11.0−11.5−18.0−20.00.0 −6.0 −6.0TABLE 6.1  Noise and Dynamic-Range Characteristics ch06.indd   8 12/17/07   2:03:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 The only  nondeterministic errors are a result of the D/A converter performance in the form of  internal clock jitter or additive thermal noise and the effect of the phase noise on the  input clock signal. Internal D/A converter clock jitter produces phase modulation of the output signal  proportional to the output frequency. Similarly, phase noise present on the clock input  signal is transferred to the output signal, reduced by 20log10 (fout / fclk) dB. 
 The annual investment in urban construction exceeds 20 billion dollars and many new buildings and transport facilities are constructed. Building a foundation often requires pumping groundwater during excavation, which could result in subsidence. In addition, when the soil underneath a building could no longer support the loading, the building will start to settle. 
 ,Ê / 
 FREQUENCY AIRBORNE RADAR FOR ATMOSPHERIC RESEARCH v  PRESENTED AT CD #ONF 2ADAR -ETEOROL  02  !LBUQUERQUE    4 +OZU ET AL  h$EVELOPMENT OF PRECIPITATION RADAR ON 
 Except for multipliers and dividers, the measurement of additive or excess phase noise* on components such as power amplifiers is considerably easier than the similar measurements on sources. All that is required is one moderately quiet source, a phase shifter, a phase detector, a suitable wave analyzer, and a method of calibration. The commercial instruments, described above, provide all this and much more. 
 PLER FREQUENCIES OUTSIDE THE STOPBAND ARE PASSED ONTO DETECTION PROCESSING 0ULSE DOPPLER RADARS  ON THE OTHER HAND  RESOLVE AND ENHANCE TARGETS WITHIN A PARTICULAR DOPPLER BAND WHILE REJECTING CLUTTER AND OTHER RETURNS OUTSIDE THE DOPPLER BAND OF INTEREST 4HIS IS TYPICALLY ACCOMPLISHED WITH A CONTIGUOUS BANK OF DOPPLER FILTERS FORMED BETWEEN TWO OF THE COHERENT PULSE TRAINS SPECTRAL LINES  ONE OF WHICH IS THE CENTRAL LINE 2ANGE GATING PRECEDES THE DOPPLER FILTER BANK 4HE BANDWIDTH OF EACH DOPPLER FILTER IS INVERSELY PROPORTIONAL TO THE DURATION OF THE COHERENT PULSE TRAIN THAT IS PROCESSED TO FORM THE DOPPLER FILTER BANK 4HIS PROCESS FORMS A MATCHED FILTER TO THE ENTIRE PULSE TRAIN   -4) AND PULSE DOPPLER RADARS SHARE THE FOLLOWING CHARACTERISTICS L #OHERENT TRANSMISSION AND RECEPTION THAT IS  EACH TRANSMITTED PULSE AND THE RECEIVER  LOCAL OSCILLATOR ARE SYNCHRONIZED TO A FREE 
 Sledge: The Possibility of Cross Modulation in the SCAMP Signal  Processor, Proc. IEEE, vol. 53, pp. 
 vol. 5, Radar Clutter." Artech House, Inc., Dedham, Mass.. 1975. 
 STATE RADAR SYSTEMS %ACH SYSTEM INCORPORATES PRIMARY  SURVEILLANCE RADAR  SEC 
 Surfaces containing vegetation and conglom - erate rocks almost completely defy description. Statistical descriptions of surfaces are used for most theories, since a theory should  be representative of some kind of surface class, rather than of a particular surface,  and since exact description is so difficult. The statistical descriptions themselves must  be oversimplified, however. 
 Indetail, thespecification called forthedetection ofan airplane 50ftabove the ground at10miles range and aircraft athigher altitudes at15miles range. Also, the system later proved most useful formeasuring velocities ofprojectiles. Itwill beobserved that, inprinciple, the simple device shown in Fig. 
 III. This would also have improved the noise- limited detection by increasing the pulse- to-pulse integration on the display. The elevation beam pattern of ASV Mk. 
 April, 1959.  63. Gunderson. 
 40.Bussgang, J.J.:Sequential Methods inRadarDetection, Proc.IEEE,vol.58,pp.731-743, May,1970. 41.Guarguaglini, P.F.,andF.Marcoz: TheDFTSD: ASequential Suboptimum Processor forMultiple­ range-bin RadarSystems, IEEETrans.,vol.AES-I0, pp.193-203, March,1974. 42.Brennan, L.E.,andF.S.HiI~Jr.:ATwo-step Sequential Procedure forImproving theCumulative Probability ofDetection inRadars,IEEETrans.,vol.MIL-9,pp.278-287, July-October, 1965. 
 The  basic idea is to find a time interval, TA, representing the desired maximum clear range,  and then to choose a set of PRIs in which all will be clear at maximum range. This can  be achieved by dividing TA by an integer, typically 9 to 17. This set will generally not  provide 96% clear over the range-doppler space. 
 Oceanic Technol ., vol. 14,   pp. 1502–1512, 1997. 
 4ARGET 4RACKING   0AUSE 
   PP n    % 4 "AYLISS  h$ESIGN OF MONOPULSE ANTENNA DIFFERENCE PATTERNS WITH LOW SIDELOBES v  "ELL 3YST  4ECH *  PP n  -AYn*UNE   $ + "ARTON AND ( 2 7ARD   (ANDBOOK OF 2ADAR -EASUREMENT   %NGLEWOOD #LIFFS  .*    0RENTICE 
 TARGET DETEC 
 ,-\·'.{,\~ ,)t;j1/,. "' · ,., , ,  Figure 7.30 E-2C AEW aircraft with rotodome antenna. RADAR ANTENNAS 269  Weather efTecls. 
 878-885, November, 1968. (Also available in ref. I.)  8. 
 14·28  The logarithmic receiver has an output voltage whose amplitude is proportional to the  logarithm of the input envelope. A logarithmic characteristic provides a constant false alarm  rate (CFAR) when the input clutter or noise has a Rayleigh pdf. The performance of the log­ arithmic receiver in non-Rayleigh clutter is almost as good as the m-out-of-11 detector and is  probably easier to implcment.14·28  A comparison of the performance of the various receivers for a specific case is shown in  Fig. 
 Update the coefﬁcient vector xk Rto be the ﬁrst column of Vmultiplied by Δ(1, 1). •Set J=J+1. 2.4. 
 Nar. Bur. Stds.)  mountainous terrain also shows no frequency dependence from L to ,Y band but is con-  siderably lower at UHF; rough hills, desert, and cultivated farmland show a linear depen-  dence with frequency; and the backscatter from marsh varies as the power of frequency. 
 the range gates are centered on the pulse.  The range gating necessary to perform automatic tracking offers several advantages as by­ products. It isolates one target, excluding targets at other ranges. 
 With it the  relationship between the measured scattering matrix [ S m] and [S c] can be described.  Becau se  of the many crossovers of the paths, which arise with a polarimetric system, a three - dimensional representation is advantageous.  In Figure 11.7 this 3 -D signal flow graph is de m- onstrated by a cube, with which lie the signal paths on the edges and diago nals. 
 D. J. McLaughlin, V . 
 89.Trunk,G.V.:RangeResolution ofTargets Using Automati~ Detectors, NavalResearch Laboratory Rl'rt.X17X.Nov.2X.1977,Washington. D.C.Also.IEEETral/s.•vol.AES-14,pp.750-755,September. 1978. 
 De Maio, A Farina, and G. Foglia, “CFAR behavior of adaptive detectors: an  experimental analysis,” IEEE Trans ., vol. AES–41, no. 
 THE 
 IEE (London) Conf.  Puhl. no. 
 Schwartzman, and A. E. Hylas: Dome Radar-A New Phased Array System,  Record of rite IEEE 1975 l11ternatio11al Radar Conference, pp. 
 155.  IX. Thraves. 
 25. B.G. Fejer and M. 
 After thedischarge isover, intheabsence !!% t-+Lessthan0.01psec ~ J “Flat” FIG. 11.16.—TR leakage power during a1-P59c pulse.space around itbeing awaveguide FIG. 11.17 .—1B24 TR tube: 3-cm band. 
 Moreover, as the formulas below will show, the deviation of the recovered signal can be twice as great as that of the transmitter. (The returning signal may be swinging up while the transmitter is swinging down.) The peak voltage of the first harmonic sideband in the IF spectrum of an FM signal mixed with itself after a time delay T = 2RIc is6 / WP \Vpi =/, 2—^simr/mr \ Jm / and the peak voltage of the carrier is I bfp \ vpo = Jo 2—1 sin ir/mT \ Jm / In both formulas AFP is the peak frequency deviation of the carrier. As before, J1(X) ~ x/2, J0(X) ~ 1, X<1. 
 Masuko et al.,31  NRL 4FR,25 M. I.  Skolnik,2 and F. 
 Doppler scintillation and spectral  lines caused by a complex target may be divided into two phenomena43: (1) spectral  lines caused by parts of the aircraft such as propellers and jet turbine blades, and (2) a  continuous doppler spectrum spread by the motion of an aircraft in flight symmetrically  FIGURE   9.25  Typical spectral-energy distributions for the three views of the SNB aircraft: ( a) nose view,  (b) side view, ( c) tail view, and ( d) side view of two small two-engine aircraft flying in formation ch09.indd   36 12/15/07   6:07:45 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 
 Itseems likely that theradar sets and beacons will bedesigned together asparts ofasystem operating at3000 31c/sec orhigher. There appears tobelittle tobegained bytrying tohave this system operate atthe same frequencies asthe beacons foruse with air- borne radar sets unless itisrequired that thesame beacons that aretobe interrogated bythe ground radar sets also reply tointerrogation by airborne radar sets. 8.5. 
 CANT AFTER !$# NOISE IS REDUCED THROUGH FILTERING &)'52%   3IGNAL 
 , vol. 31, pp. 962–994, 1953. 
 After ASV Mk. II enteredservice it had previously been estimated that daytime sighting of U-boats had increased by 20%. If as a result of using a listening device 50% of U-boats were diving before they were contacted, it was concluded that daylight operation of ASVwas in fact a de ﬁnite disadvantage and it was recommended that daylight use be suspended. 
 H Hooke:" Waves in the Atmosphere," Elsevier Scientific Publishing Co.,  New York, 1975.  109. Saxton J. 
 E., and (i. N. l'sandoulas: Ferroscan: Toward Continuous-Aperture Scanning, IEEE Trtrrr.~. 
 BIT "!- NOTA 
  OR RECEIVE 
 Sherman. J. W.: Aperture-antenna Analysis, chap. 
 246–254, 1960. 16. S. 
 3315, 2004. 150. E. 
 An approach is to cascade the SLC and SLB techniques as shown in Figure 24.4. The  scheme depicts three receiving channels, each one having an antenna, a receiver, and  an ADC; they provide three signals labeled, respectively, as SLC, MAIN , and SLB.  The left-hand side antenna is a low-gain auxiliary performing the SLC processing in FIGURE 24.3  Contour curve of JCR (dB) versus the amplitude (in natural  number, along the horizontal axis) and phase (in degrees, along the vertical axis)  mismatches of the analogue receiving channels0 0.02 0.04 0.06 0.0800.511.52 4035 3530 30 3025 25 25b (°)  an ch24.indd   17 12/19/07   6:00:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Let usassume that Nrandom pulses persecond arereceived byabeacon, and that the beacon istriggered ifany pulse isfollowed byasecond one that arrives later byaninterval oftime between D–Tand D+T.Disthedelay, and ~Tisthetolerance. Each pulse thus produces afollowing interval. 268 RADAR BEACONS [SEC. 
 IN 
 26.  pp. 297-305, March. 
 PRESSION  4HE OUTPUT OF AZIMUTH COMPRESSION IS SHOWN AT POINT # 4HE COMPLEX 3!2 OUTPUT MAP MUST BE CHECKED FOR DEPTH OF FOCUS AND USUALLY REQUIRES AUTOFOCUS SINCE BOTH ATMOSPHERIC EFFECTS AND LOCALLY RISING OR FALLING TERRAIN MAY CAUSE DEFOCUSING 3UBSEQUENT TO REFOCUSING  THE MAP IS MAGNITUDE DETECTED AND HISTOGRAM AVERAGED TO MAINTAIN UNIFORM BRIGHTNESS 4HE MAP IS INTEGRATED WITH OTHER LOOKS  WHICH REQUIRES  &)'52%  3!2 PROCESSING ADAPTED COURTESY 3CI4ECH 0UBLISHING  .   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°ÎÇ GEOMETRICAL CORRECTION AND MOTION COMPENSATION 4HE TOTAL MAP DYNAMIC RANGE CAN  EASILY BE GREATER THAN  D" 4HE TYPICAL COCKPIT DISPLAY IS LIMITED TO n D" AND DYNAMIC 
 DETECTOR STAGE OF THE RECEIVER /N EACH PULSE  THE PHASE OF THE MAGNETRON PULSE SETS THE PHASE OF THE COHO )N THIS MANNER  THE RECEIVED SIGNAL APPEARS TO BE COHERENT PULSE TO PULSE 4HIS IS SOMETIMES CALLED  COHERENT ON RECEIVE   4HE -4) IMPROVEMENT FACTOR OBTAINED WITH A MAGNETRON AND A COHERENT 
 Rept. RM-1008, Dec. 17,  1952, Santa Monica, Calif. 
 7.1 Scanning of Arra ys  ............................................  7.7  7.2 Array Theor y  ...........................................................  7.10  7.3 Planar Arrays and B eam Steering  .......................... 
 DERIVED POSITIONAL DATA (OWEVER  !)3 RELIES ON COOPERATIVE TARGETS IS PRONE TO GROSS ERRORS IN DATA ACCURACY  MAINLY  CAUSED BY SETUP ERRORS AND TOTALLY RELIES ON REASONABLY  ACCURATE '.33 DATA BEING AVAILABLE ! '.33 BLACKOUT  PERHAPS CAUSED BY INTENTIONAL OR UNINTENTIONAL JAMMING  WOULD PREVENT !)3 FROM BEING AN EFFECTIVE SYSTEM  POSSIBLY  OVER A WIDE AREA AND FOR AN APPRECIABLE TIME &UTURE SYSTEMS MIGHT INCREASINGLY EXPLOIT THE COMPLEMENTARY ASPECTS OF RADAR AND  !)3 4HIS COULD IMPROVE THE OVERALL TARGET 
 696–706, 2003. 78. Radar calibration workshop presented at 81st Annual Meeting of the Am. 
 F . Walker22 © IEEE 1971 ) ch07.indd   12 12/17/07   2:13:12 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 There have been other kincis of ferrite phase shiftcrs tlevelopetl  over the years based on different principles or on variations of those describctl above. 1  Althoilgh the above phase shifters were discussed primarily as waveguide devices, some of  tllern may he implenientect in coax, helical line, i~ncl stripline."  The ferrite Faraday rotator, which was mentioned above as being a part of the dual-mode  phase shifter, also has been applied as an electronic phase ~hifter.~~.~' It is the equivalent of the  mechanical Fox phase shiftere3' Other examples of phase shifters are a helical slow-wave  structure either surrounded by or surrounding a ferrite t~roid,~~.~' a transversely magnetized  slab of ferrite in rectangular ~aveguide,~~.~~ a bucking rotator phase sl~ifter,~~ circular polari-  zation between quarter-wave plates,44 a reciprocal, polarization-insensitive phase shifter for  reflect array^,^^ wideband phase ~hifters,"~ and phase shifters that operate at UHF." Ferrites  have also been used in continuous aperture scanning where a phase change is provided across  an aperture without subdividing it into separate elements. In one experimental design," ten  discrete phase-shifter elements were replaced with a single ferrite-loaded aperture whose  properties were externally controlled to scan the beam radiated by a five-wavelength, X-band  antenna. 
 , 
 Multiple-beam array antennas with a large number of simultaneous beams have not seen  wide application, probably because of the complexity of such systems. They have, however,  had application in 3D mechanically rotating air-surveillance radars which employ a small  number of contiguous beams stacked in elevation to provide the elevation coordinate.  In some applications, the effect of multiple, independent beams can be obtained with a  single-beam phased-array radar which is capable of flexible and rapid beam steering. 
 field of the feed. The second method, known as the aperture-field method, ob- tains the far field from the field distribution in the aperture plane. Both the cur- rent and aperture-field distributions are obtained from geometrical optics consid- erations. 
 C. G.: Tlic Design of Automatic-gain-control Systems for Auto-tracking Radar Receivers,  Proc. IEE, pt. 
 WIDE REJECTION NOTCHES IS EMPLOYED AND IF SCAN 
 vegeta­ tion, hare soil, cultivated fields. mountains, swamps, ·cities. roads, and lakes all have different  scattering characteristics. 
 Visual estimates of sea conditions ranged from 0.9- to 1.8-m waveheight. Ratios of bistatic to monostatic scattering coefficients (median values) were calculated, with bistatic angles, 0 - 180° - <|>, ranging from 23° to 85°. The data implicitly included pattern propagation factors and losses. 
 480 INTRODUCTION TO RADAR SYSTEMS  variations received from clutter. One of these is the contaminated-normal pdf which consists  of the sum of two gaussian pdfs of different standard deviations and different relative  weightings. 12 This pdf can be fitted to the data of Fig. 
 Lynch, “Radar systems for strike/fighter aircraft,” presented at AOC Third Radar/EW  Conference Proceedings , Unclassified paper in classified proceedings available from author by  request, February 12–13, 1997.  8. D. 
 TRACKING RADAR  9.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 A practical approach to monopulse feed design uses higher-order waveguide modes  rather than multiple horns for independent control of sum- and difference-signal   E fields. This allows much greater simplicity and flexibility. A triple-mode two-horn  feed used by RCA5,6 retracts the E-plane septa to allow both the TE10 and TE30 modes  to be excited and propagate in the double-width septumless region, as illustrated in  Figure 9.6. 
 Naderi, M. H. Freilich, and D. 
 18.19. The signals are each converted from RF to different IF frequencies by sep- arate local oscillators (LOs) of different frequencies for each signal. They are am- plified in a single IF amplifier of sufficient bandwidth for all three signals at dif- ferent frequencies. 
 The mismatch in the envelope delay time between successive pulses re- sults in a residual signal, sometimes called ranging noise. Figure 16.28 shows the effect of this residual on the performance of a single- delay canceler. The idealized rectangular pulse envelope gives a pessimistic pic- ture of this effect. 
 BAND SHIPBORNE RADAR ANTENNA #OURTESY OF +ELVIN (UGHES ,TD .   #)6), -!2).% 2!$!2   ÓÓ°£Î AND FALL TIMES ARE USUALLY LONGER 4HE EXTRA HIGH VOLTAGES INVOLVED CAN LEAD TO POOR  RELIABILITY IF THE DESIGN DOES NOT ADEQUATELY ADDRESS THE ASSOCIATED PROBLEMS #AREFUL PHYSICAL LAYOUT IS ESSENTIAL AND CONSIDERATION MUST BE GIVEN TO THE EFFECTS OF OPERATING IN A POTENTIALLY DAMP ENVIRONMENT  0ULSE TIMING CAN BE PURPOSELY JITTERED ON A PULSE 
 SOURCE TUBE AMPLIFIER AND THE FACE OF THE ARRAY ARE THUS ELIMINATED )N ADDI 
 EMATICALLY BUT EASY TO UNDERSTAND QUALITATIVELY 4HUS IT IS EASY TO SEE THAT A FRESHLY  PLOWED FIELD IS ROUGHER THAN THE SAME FIELD AFTER RAIN AND WIND HAVE BEEN AT WORK ON IT ! FOREST IS INHERENTLY ROUGHER THAN EITHER A FIELD OR A CITY )T IS HARDER TO SEE THE DIFFERENCE BETWEEN THE ROUGHNESS OF NATURAL AREAS AND THE ROUGHNESS OF A CITY THAT HAS FLAT WALLS INTERSPERSED WITH WINDOW SILLS AND WITH CURBS  CARS  AND SIDEWALKS 3URFACES THAT ARE RELATIVELY SMOOTH TEND TO REFLECT RADIO WAVES IN ACCORDANCE WITH  THE &RESNEL 
 2.17 for B-47 were obtained by calculation.  The most realistic method for obtaining the radar cross section of aircraft is to measure  the actual target in flight. There is no question about the authenticity of the target being  measured. 
 ",9 !RRAY WITH 4WO %LEMENTS  &IGURE  SHOWS TWO ISOTROPIC RADIATORS THAT ARE  SPACED BY A DISTANCE  S AND EXCITED WITH EQUAL AMPLITUDE AND PHASE 7ITH UNITY INPUT &)'52%  !PERTURE DISTRIBUTION GIVING TWO BEAMS . £Î°£ä  2!$!2 (!.$"//+  POWER  THE VECTOR SUM OF THEIR CONTRIBUTIONS  ADDED AT A GREAT DISTANCE AS A FUNCTION OF  P  IS THE RADIATION PATTERN   %E EAJS JS  ;     SIN     SIPP 
 RANGE DIRECTION . 
 17 .34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 A number of authors report successful results with FOPEN SAR, using such  SARs as the Environmental Research Institute of Michigan P-3 SAR,58,59 the  Swedish National Defense Research Establishment CARABAS sensor,60 and the SRI  International Ultra-Wideband SAR.61 Furthermore, Moyer62 presents images from  conventional and FOPEN SARs showing that vehicles under trees may be imaged  significantly better with FOPEN SAR than with conventional SAR; example imagery  is given in Figure 17.16. REFERENCES  1. R. 
 OFF IN TARGET 2#3 u  -UST NOT INTERFERE WITH OTHER USERS IN THE CROWDED (& SPECTRUM  THUS LIMITING CHOICE OF FREQUENCY AND BANDWIDTH u  -UST ADAPT CONTINUALLY TO THE CHANGING IONOSPHERE SO AS TO MAINTAIN ILLUMINATION OF CURRENT TARGET REGION .OISE FLOOR DOMINATED BY )NTERNAL RECEIVER NOISE  THERMAL  ETC 3OURCES ATMOSPHERIC  GALACTIC  ANTHROPOGENIC  ETC  3ITING CONSTRAINTS u  5NOBSTRUCTED  ELEVATED SITES PREFERREDu  2ECEIVE ARRAY SITE MUST BE %- QUIET  GENERALLY RURAL  TO AVOID CITY AND INDUSTRIAL NOISE AT (& FREQUENCIES u  (UGE ARRAYS REQUIRE FLAT  OPEN SPACES TO MINIMIZE TOPOGRAPHIC EFFECTS ON BEAM PATTERNS u  )F A BISTATIC OR TWO 
 PROPAGATION OF RADAR WAVES 445  700 I I I I I I I I  3,000 Mt+z  100  tlorizonlol polorizot~on 100 MHz  160 -  <f. P)  '1 140 - C 2 2 120 A:-Verticol polorizotion - w 0 / u : I00  U a - 5 80 - 0 : 60  n  0 I I I I I I 1 I  0 10 20 30 40 50 60 70 80 90  Groz~nq angle, deq  Figtit-e 12.3 ((1) Mitgnitiide oT the reflection oocflicient as a function of the grazing angle (Tor sea-  water) (h) Phase of the reflection coeficient as a function of the grazing angle (for seawater). Phase of  Illc rcflcclcd wave Iitg~ ~IIC I~I;I~C of the~irlcidcnt wave (Front Brrl.rorvs c11rc1 Artr~ood.~ caltrresy Acc~dr.rrric  /'rr*5x, Ir1c )  For a rougli, perfectly cotlducting surface, such as the sea, Ament70 derived the reflection  cocfficic~it as  po exp [ - 2k2p sfnZ $1  wtlere 9,, = complex rellectiot~ coefficient for a smooth su&ace  k = 2n/A  1 = wavelength  /I' = mean-square surface height (mean value of A = 0)  CI/ = grazing angle  Experimental data taken over the sea fit this expression well; except for large values of the  roughness hrarneter [(\I sin $)/A z lt!/~jA > 0.1 I], where the theory underestimates the experi-  mental ob~ervations.~  The rcflection of electromagnetic waves from the sea may be separated into a coherent and  an ~ttcolterettt component.7' 73 The coherent component has a reflection coefficient whose  amplitude and phase are fixed by a given geometry and sea state. 
 TO 
 112. D. Trizna (private communication), 1989. 
 Conﬂicts of Interest: The author declares no conﬂicts of interest. References 1. Chang, W.; Tao, H.; Sun, G.; Wang, Y.; Bao, Z. 
 The ArcSAR system parameters. r (m) θbw(rad) θ(rad) λ(mm) Rsp(m) Br(MHz) 1 π/3 π/3 17.50 300 150 Rspis the minimum slant range between the antenna and the target during the rotation. The relationship between height of the target and ΔRmaxis as follows: Rp0max−Rpmax =ΔRmax (17) Rp0max =⎭radicalBigg ⎭parenleftbigg rsinθ 2⎭parenrightbigg2 +⎭parenleftbigg Rsp+r−rcosθ 2⎭parenrightbigg2 (18) Rpmax =⎭radicalBigg ⎭parenleftbigg rsinθ 2⎭parenrightbigg2 +⎭parenleftbigg⎭radicalBig Rsp−h2+r−rcosθ 2⎭parenrightbigg2 +h2 (19) where Rpmax is the maximum slant range between the antenna and the target P during system rotation, Rp0max represents the maximum slant range between the antenna and P 0during system rotation. 
 1965. (/\ vailahlc from lJ .S. ( iovcrnrnent Printing Office.)  2J. 
 H .. and C. E. 
 UNAMBIGUOUS RANGE (nmi) FIG. 17.16 Unambiguous range for two- and three-PRF ranging systems as a function of ranging parameters, W1-I, and minimum value of PRF for the case where mly W2, W3 are consecutive integers and m, is odd. 1. 
 ££°£n  2!$!2 (!.$"//+  )N THE CORPORATE 
 Benedict72 suggests that to minimize the output noise variance at steady state and the tran­ sient response to a maneuvering target as modeled by a ramp function, the cx.-P coefficients are  related by f1 = cx.2/(2 -a). The particular choice of ex. within the range of zero to one depends  upon the system application, in particular the tracking bandwidth. 
 The shortest resonant piece ofsuch awaveguide istherefore square. The height does not affect the resonant wavelength, though if itisgreater than A/2, modes polarized atright angles tothedesired mode become possible. Rounding offthe corners ofthe square box shortens the resonant wavelength slightly; exact calculation shows that for a cylindical box theresonance occurs when X=1.30 times thediameter, as opposed to1.41 times the side ofthesquare. 
 The U.S. Tactical Air Commands. -Each U.S. 
 52. D. E. 
 J.Applied 1'i1l'sics. vol.25.pp.1413-1421.November. 1954. 
 55. E. F. 
 Sci. Rep. 2016 ,6, 28160. 
 56. H. D. 
 In receive, the signal from each of the 56 subarrays is fed into a receive beamforming network. The transceiver module contains predriver, driver, and final transmit output stages, transmit/receive switching, low-noise amplifiers, limiter, phase shifters, and logic control. The transceiver module block diagram is shown in Fig. 
 BASED  TARGET DECOMPOSITION THEOREMS IN RADAR POLARIMETRY v  )%%% 4RANS 'EOSCIENCE AND 2EMOTE  3ENSING  VOL   PP n    3 2 #LOUDE AND + 0 0APATHANASSIOU  h0OLARIMETRIC 3!2 INTERFEROMETRY v  )%%%  4RANS  'EOSCIENCE AND 2EMOTE 3ENSING  VOL   PP n    3 2 #LOUDE AND % 0OTTIER  h!N ENTROPY BASED CLASSIFICATION SCHEME FOR LAND APPLICATIONS OF  POLARIMETRIC 3!2 v )%%% 4RANS 'EOSCIENCE AND 2EMOTE 3ENSING  VOL   PP n    , 
 SHIFTER CONTROL CIRCUITS EXISTS BEHIND THE REFLECTOR 4O AVOID  APERTURE BLOCKING  THE PRIMARY FEED MAY BE OFFSET AS SHOWN !S BEFORE  TRANSMITTING AND RECEIVING FEEDS MAY BE SEPARATED -ULTIPLE BEAMS ARE AGAIN  POSSIBLE WITH ADDI 
 BASED RADAR  DESIGNED SPECIFICALLY TO MEASURE OCEANIC WINDS )T WAS A MULTI 
 Magnetron performance and lifearematerially increased ifthepulser design issuch that, intheevent ofsparking ormode-shifting, anexcessive discharge does not take place through themagnetron. These two types ofinstability, mode-changing and sparking, arediffi- cult todistinguish inpractice, since mode, changing usually produces sparking and vice versa. Inspite ofthis, itisadvantageous toconsider them separately since thecure foreach isquite specific and distinct. 
 This was suggested by the K-band curves shown in Fig. 13.5 for moderate wind speeds and further supported by some older shipboard data at frequencies between 9 and 49 GHz.45 It should be noted that clutter signal paths lie close to the sea surface, where the atmospheric and water-vapor densities are highest. This means that at these higher frequencies the clutter signal will be strongly affected by the atmospheric absorption effects described in Chap. 
 Two modules and a 33-V dc power supply make up a single transmitting group. The module consists of a 2-8-32 amplifier configuration of silicon bipolar power transistors. The 32 final output devices and the eight driver devices are 100-W transistors ca- pable of operating up to a 10 percent duty cycle over the 100-MHz bandwidth at collector efficiencies greater than 52 percent. 
 11.2. Atthe proper frequency theinput impedance of the short-circuited stub isextremely high and there isnoeffect onthe propagation ofthe wave onthe line. InFig. 
 Their only purpose is to relate the peak value of the function to the more vital energy content. Of these parameters, only the energy of the pulse is easy to measure (average power/PRF), and this may be employed in the radar range equation directly, without distinguishing peak power and "energy" pulse width. The noise or en- ergy bandwidth of a receiver is often employed in theoretical analyses but rarely stated in the tabulation of radar parameters; bandwidth need not even be included in the radar range equation if the receiver approximates a matched filter. 
 CloudSat154 flies in a sun-synchronous orbit in  close formation with CALIPSO, which carries a cloud-profiling lidar, and in some - what looser formation with Aqua, Aura, Terra, and PARASOL. Taken together, these  six environmental satellites constitute the so-called A-Train. The average separation  between CloudSat and CALIPSO is about 460 km, which corresponds to a one-minute  delay between the radar and lidar cloud profiling measurements. 
 BIAS RETURN  AND IN COMMON BASE OPERATION  THIS WILL RESULT IN DEGRADED POWER GAIN. ££°Óä  2!$!2 (!.$"//+  L #LASS 
 Inorder toreduce theeffect oflag, thesystem isoften “geared up.” For example, the transmitter synchro can be attached toashaft rotating 10times asfast asthescanner, and thereceiv- ing synchro can then drive arotating PPI deflection coil through a 10-to-l gear reduction. Under these conditions, the lag error can be kept toasmall fraction ofadegree. There is,however, a10-fold uncer- tainty inthe position ofthe deflection coil inour example, since any of 10antenna positions looks the same tothe receiver. 
 Ê 
 In practice, the power received from an antenna with a cosecant-squared pattern is not  tri~ly independent of range because of the simplifying assi~mptions made. The cross sectloll cr  varies with the viewing aspect, the earth is not flat, and the radiation pattern of any real  antenna can be made to only approximate the desired cosecant-squared pattern. The gain of a  typical cosecant-squared antenna used for ground-based search radar might be about 2 dB  less than if a fan beam were generated by the same aperture. 
   . 
 R. Ward:" Handbook of Radar Mcasun:ment," Prl.!nticc.:-llall, Inc, Engkwoo<l  Cliffs, N.J., 1969.  42. 
 ARI 5205 with high-power transmitter, T.3140, and separate modulator, type 52 installed in a Sunderland [ 7].Airborne Maritime Surveillance Radar, Volume 1 2-16. 2.2.4 ARI 5136, common T & R As mentioned in section 2.2.2.2 , a common transmit and receive (T & R) facility was introduced on some aircraft, so that a separate transmit antenna was not required. This installation required a separate motor-driven switch unit for both antenna and receiver-output switching, together with spark-gap protection for the receiver duringtransmission. 
   AVERAGING #&!2  RATIO DETECTORS  LOG INTEGRATOR  AND BINARY INTEGRATOR 2AYLEIGH  PULSE 
 319–320, April 1984. 26. T. 
 62.  pp. 582-61 1. 
 Remote Sens. 2017 ,9, 125. [ CrossRef ] 35. 
 D" BEAMWIDTH )F  +. PULSES ARE IN THE  
 Sincethetrailing edgeofthepulsedepends onhowthepulse-forming network discharges intothenonlinear load,thctrailingedgeisusuallynotsharpahditmaybedifficulttoachievethedesiredpulse shape. Thecharging inductance Lchandthecapacitance Cofthepulse-forming network forma resonant circuit,whosefrequency ofoscillation approaches fo=(271tl(Lchct1/2.(The inductance ofthepulse-forming network andtheloadareassumed small.)Withad-cenergy sourcethepulserepetition frequency fpwillbetwicetheresonant frequency ifthethyratron is switched atthepeakofmaximum voltage.Thismethodofoperation, ignoring theefTectofthe charging diode,iscalledd-cresonantcharging. Adisadvantage ofd-cresonant charging isthat thepulserepetition frequency isfixedoncethevaluesofthecharging inductance andthe pulse-forming-network delay-line capacitance arefixed.Rowever, thecharging, orhold-ofT, diodeinsertedinserieswiththecharging inductance permitsthemodulator tobeoperated at anypulserepetition frequency lessthanthatdetermined bytheresonant frequency fo.The function ofthediodeistoholdthemaximum voltageandkeepthedelaylinefromdischarging untilthethyratron istriggered.26Although theseriesdiodeisaconvenient methodforvarying theprf,itismoredifficult tochangethepulsewidthsincehigh-voltage switches inthe .. 
 The repeat period FIGURE 18.1  The Seasat satellite, featur - ing the antennas of its three radars ( Courtesy  of NASA ) ch18.indd   2 12/19/07   5:13:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 LOBE CANCELERS  AND ADAPTIVE ARRAY SYSTEMS 3OME OF THESE TECHNIQUES ARE USEFUL DUR 
 181. sensors Article Performance Analysis of Ionospheric Scintillation Effect on P-Band Sliding Spotlight SAR System Lei Yu, Yongsheng Zhang *, Qilei Zhang, Yifei Ji and Zhen Dong College of Electronic Science and Technology, National University of Defense Technology, Changsha 410073, China; yulei17@nudt.edu.cn (L.Y.); zhangqilei@nudt.edu.cn (Q.Z.); jyfnudt@163.com (Y.J.); dongzhen@nudt.edu.cn (Z.D.) *Correspondence: zyscn@163.com; Tel.: +86-135-7483-8648 Received: 24 March 2019; Accepted:7 May 2019; Published: 9 May 2019/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: The space-borne P-band synthetic aperture radar (SAR) maintains excellent penetration capability. However, the low carrier frequency restricts its imaging resolution. 
 Moving the zeros can provide a 4 or 5 dB increase in the MTI  improvement factor for specific clutter spectral spreads, as compared with keeping all  three zeros at the origin.25 Note the width of the rejection notches for the different binomial-weight canceler  configurations. If the −6 dB response relative to average response is used as the mea - suring point, the rejection is 24% of all target dopplers for the single canceler, 36%  for the dual canceler, and 45% for the triple canceler. Consider the dual canceler:  Eliminating 36% of the dopplers means limiting the system to a long-term average of  64% single-scan probability of detection. 
 Goodman: Geodesic Lenses for Radar Antennas, EASCON Rec., 1968.  pp. 64- 69. 
 D. L., H. D. 
 S  LESS THAN A  DECADE AFTER THE PROJECT WAS FUNDED BY THE $EFENSE !DVANCED 2ESEARCH 0ROJECTS  !DMINISTRATION $!20!  !N !SSOCIATED 0RESS PHOTO OF THE AIRCRAFT MOCKUP IS SHOWN IN &IGURE  4HE AIRFRAME IS  FT WIDE AND  FT LONG 4HE NOSE ANGLE OF THE PLANFORM IS NEARLY DOUBLE THAT OF THE & 
 R. Varschney and D. Thomas, “Sidelobe reduction for matched range processing,” 2003 IEEE  Radar Conference , pp. 
 DOPPLER ELEMENT SPACE ARCHITECTURE. Î°Ón  2!$!2 (!.$"//+  FOR THE GIVEN PLATFORM MOTION  THESE THREE APERTURES APPEAR AS IF THEY ARE STATIONARY  WITH RESPECT TO EACH OTHER #LUTTER CANCELLATION ACROSS THESE THREE PULSES IS NO LONGER LIMITED BY PLATFORM MOTION EFFECTSTHE PRIMARY GOAL OF PLATFORM MOTION COMPENSATION TECHNIQUES /F COURSE  THIS SIMPLEST CONDITION IS ONLY ILLUSTRATIVE  AS GENERALLY THE ANTENNA ELE 
 (ILL "OOK #OMPANY   3EC  
 2ESEARCH  2ADIOTECHNICAL )NSTITUTE  -OSCOW    ! ' "LYAKHMAN ET AL  h&ORWARD SCATTERING RADAR MOVING OB JECT COORDINATE MEASUREMENT v  )%%% )NTERNATIONAL 2ADAR #ONFERENCE    ! 4HOMSON   ! '2!6%3 3OURCEBOOK  VERSION OF  
 IEEE , vol. 53, pp. 920–928, August 1965. 
 A similar explanation is given by the Admiralty Signal  Establishment for that ingenious circuit the one-valve  “flip-flop,” called in America the transitron. It consists  of a pentode with its suppressor and screen grid linked  by a condenser. By suitable choice of component values  . 
 The 5J26, for example, has been used in search radars for over 40 years. It operates at L band and is mechanically tunable from 1250 to 1350 MHz. It is typically operated at 500-kW peak power with 1-jxs pulse duration and 1000 pulses per second (pps), or 2 jxs and 500 pps, either of which is 0.001 duty cycle and provides 500 W of average RF power. 
 In fact, even fixed radars frequently observe fluctuations in ground echoes because of motions of vegetation, automobiles, etc. Regardless of the model used to describe a ground surface, signals are, in fact, returned from different positions not on a plane. As a radar moves past a patch of ground while illuminating it, the look angle changes, and this changes the relative distances to different parts of the surface; the result is that relative phase shift is changed. 
 Manyoftheadvantages offrequency agilitycanbeobtained iftheradarfrequency shiftspulse-to-pulse theminimum amount required todecorrelate successive echoes.The minimum frequency shiftisequaltothereciprocal ofthepulsewidth.Slowtuningratescanbe used,butthepulse-to-pulse frequency mightnotappearrandom. Oneof·thefirsttechniques forachieving frequency-agile magnetrons wasknownasspin­ tWlillg,orrotarytIming.Inthisdevicearotating slotteddiskissuspended abovetheanode resonators. Rotation ofthisdiskalternately provides inductive orcapacitive loadingofthe resonators toraiseandlowerthefrequency. 
 +1, 
 The voltages themselves can betransmitted byapoten- tiometer, oramodulated carrier can beused asin(2). The approximations sind=6and cos6=1amoften {Ised. 13.4. 
 ]Ê / 
 Slight changes in viewing aspect or frequency result in large fluctuations in cross section.  Nevertheless, a single value of cross section is sometimes given for specific aircraft targets for  use in computing the radar equation. There is no standard, agreed-upon method for specifying  the single-valued cross section of an aircraft. 
 It is produced by Euro-Art GmbH, a consortium of  Lockheed Martin MS2 (Moorestown, NJ), EADS Deutschland (Unterschleissheim,  Germany), Thales Air Defence (Bagneux, France), and Thales UK, Limited (Crawley,  West Sussex, England), for the Ministries of Defence of France, Germany, and the  United Kingdom. Volume Search Radar.  The S-band V olume Search Radar (VSR) phased array (see  Figure 13.43) provides search and AAW capability to the Dual Band Radar System  for DD(X). 
 , 
 These are usually digitized in a large number  of range gates ( ≈1000) at the radar’s pulse repetition frequency. The resultant complex  time series in each gate can then be processed by using a fast Fourier transform (FFT)  to obtain an estimate of the doppler power spectrum83 from which the echo power,  mean velocity, and spectrum width can be obtained. FIGURE   19. 
 The return from the tip is very small in the nose-on region, and the RCS pattern is dominated by the echo from the base. Figures 11.9 and 11.10 are patterns of the RCS of a 15° (half-angle) cone with a base circumference of 12.575X. Both patterns were measured as the cone was rotated about a vertical axis parallel to the base of the cone. 
 13”13). 2.Those inwhich anexternally induced departure from astable state with production ofawave front islater followed byaspontaneous return which produces the wavefront ofopposite polarity (Fig. 13.14). 
 The angular velocity ofthe fast rOrotation isdetermined byH. 332 THEMAGNETRON ANDTHEPULSER [SEC. 10.3 alone ;itisuO =eH/m. 
 REFERENCED COORDINATE SYSTEM IS USED THROUGHOUT THIS CHAPTER  &IGURE  SHOWS THE COORDINATE SYSTEM AND PARAMETERS DEFINING BISTATIC RADAR OPERA 
 16.6; instead ofbeating the signals with anr-freference signal, the same thing isnow done atintermediate frequency. This is accomplished byapplying the superheterodyne principle both tothe locking pulse and tothe signals. The same stable local oscillator pro- vides asignal totwo mixers, one ofwhich reduces the frequency ofthe locking pulse, the other the frequency ofthe signals, to30Me/see. 
 In  addition, modern navigation aids work so well that each radar mode is defined by  its earth situation-geometry with almost all waveform parameters set by local earth  conditions.7,9 The modern radar often is net-centric, using and providing data to a  communications network and where suitably equipped, has its own Internet protocol  (IP) address. Multifunctionality is not dependent on antenna type. In fact, the mechanically  scanned AN/APG-65, 70, and 73 radars have demonstrated multifunctionality in  combat.7 However, multifunctionality is facilitated by Active Electronically Scanned  Antenna (AESA) arrays. 
 X.IJomh.C,andMII.L.Pryce:TheCalculation ofFieldStrengths overaSpherical Earth.J.lEE. vol.94.pIIIr,pp..125 .~39.1947. 9.Senior.T.B.A.:RadioPropagation overaDiscontinuity intheEarth'sElectrical Properties. 
 POLARIZED SYSTEMS 4HE MODIFIER hCOHERENTv HELPS TO DISTINGUISH  p  $IFFERENTIAL INTERFEROMETRIC SYNTHETIC APERTURE RADAR. 
 In addition, the microwave landing system and the widely used  ATC radar-beacon system are based in large part on radar technology.  Aircv-aft Nac~iqatiotl. The weather-avoidance radar used on aircraft to outline regions of preci-  pitation to the pilot is a classical form of radar. 
 THE RADAR EQUATION 29  change in signal-to-noise ratio is much greater than this for a given change in detection  probability, as discussed in Sec. 2.8.) Also, the signal-to-noise ratio required for detection is  not a sensitive function of the false-alarm time.For example, a radar with a 1-MHz bandwidth  requires a signal-to-noise ratio of 14.7 dB for a 0.90 probability of detection and a 15-min  false-alarm time. If the false-alarm time were increased from 15 min to 24 h, the signal-to-noise  ratio would he increased to I S.4 dB. 
 DELAYED SIGNALS ARE SAMPLED AND USED TO GENERATE THE ADAPTIVE WEIGHTS 6ARIOUS ALGORITHMS ARE P OSSIBLE TO GENERATE THE  ESTIMATE OF THE ADAPTIVE WEIGHTS FROM %Q  4HE FAIRLY SIMPLE ,EAST -EAN 3QUARED ALGORITHM GENERALLY YIELDS FAIRLY SLOW CONVERGENCE RATES /THER ALGORITHMS   CAN  SPEED UP THE ADAPTATION RATE  BUT A MORE COMPLEX MECHANIZATION IS REQUIRED %XAMPLES INCLUDE A 2ECURSIVE ,EAST 3QUARED ALGORITHM  1 
 (25.2O).123 Hence (orA = y (sin 0,- sin 05)1/2 (25.21) where (cr^0)^ is the scattering coefficient in the bistatic scatter region. Now y can be estimated from Fig. 25.10 by using monostatic data, which is plotted along the line 0, = Qs. 
 !USTRALIA'ENERAL %LECTRIC 53!2AYTHEON 53!/.%2!  &RANCE.))$!2  2USSIA 9EAR OF FIRST TARGET DETECTIONS      #ONFIGURATION 1UASI 
 In general SAR imaging applications, it can be ignored. However, the change in the range resolution will lead to inaccurate matching and affect the quality of the fusion in image matching. In the proposed method, in order to unify the bandwidth of ky in different view images, the center value of kyis ﬁrst determined, and then the bandwidth of kyis determined according to the bandwidth of the kr. 
 AIR MODE SOFTWARE LEVEL  THERE IS ADAPTIVE TASK PRIORITIZATION TO INSURE THAT THE HIGHEST PROCESSOR PRIORITIZED  PILOT 
 GIES ARE SIGNAL PROCESSING  SUCH AS &4#  PULSE INTEGRATION  AND CORRELATION PROCESSES  BOTH PULSE 
 Thus, in a particular case, the  independent-sample rate may be determined either by the motion of the illuminated  patch over the ground or by the doppler effect or by some combination of the two. The number of independent samples determines the way in which the Rayleigh  or other distributions may be applied. Thus, if 100 pulses give only 10 independent  samples, the variance of the mean obtained by integrating these pulses is much greater  than would be true if all 100 pulses were independent. 
 (11111..  .klir~lrigut~ R~diutiotr Lab. Srlrdirs it1 Rudar Cross Sc~r.rions .Y. 
 4.9b has the same frequency-response character­ istic as the double-delay-line canceler. The operation of the device is as follows. A signal! (t) is  inserted into the adder along with the signal from the preceding pulse period, with its ampli­ tude weighted by the factor -2, plus the signal from two pulse periods previous. 
 42 
 Stabilization requires that the vehicle be equipped with a device, such as gyroscope, which  is sensitive to directions in space and which measures the deviation of the platform from its  level position. The gyroscope device used as the reference from which to stabilize the antenna  is called a stable element or a stable vertical.  The direct approach to stabilization would be to provide a stable base that maintains the  level no matter what the tilt of the ship or aircraft. 
 18.5. High scan rates are difficult to achieve with mechanical scanning devices in a large antenna, and a variety of techniques to scan electronically have been used. In a small antenna such as that used in missile-homing heads, the dish rather than the feed may be tilted and rotated at high revolutions per minute (r/min) to achieve high scan rates. 
 80. Carbone, R. E., R. 
 The values of ΔσandΔσrincrease as the radar frequency increases. 4.3. Inﬂuence of Wind Speed To analyze the inﬂuence of wind speed on SAR eddy imaging, the radar look direction and wind direction were kept constant, and wind speeds were set to be 4 m/s, 7 m/s and 10 m/s respectively. 
 The air-to-air case of Fig. 19.3/? dif- fers in that the clutter spectrum ex- tends below feedthrough due to the air- borne illuminator's backlobe, which can produce a return from a clutter patch behind the aircraft, i.e., an angle of 180° with respect to the illuminator velocity vector.ILLUMINATOR FIG. 19.2 Semiactive geometry. 
 The limited ability of CW wave-interference radar to be anything  more than a trip wire undoubtedly tempered what little official enthusiasm existed for radar.  It was recognized that the limitations to obtaining adequate position information could  be overcome with pulse transmission: Strange as it may now seem, in the early days pulse  radar encountered much skepticism. Nevertheless, an effort was started at NRL in the spring  of 1934 to develop a pulse radar. 
 The earliest service equipment tobecommercially manufactured was the CXAM radar, designed atthe Naval Research Laboratory. Alaboratory-built prototype ofthis settvas tested atseaduring battle maneuvers inearly 1939, aboard the U.S.S.NewYork,and itsperformance was sopromising that acontract was letinOctober 1939 forthemanufacture ofsixsets of similar equipment. The CXAM was operationally quite different from theCH. 
 Ideally there  should be no overlap in sub-ba nd frequency characteristics. • The noise bandwidth of the Doppler filte rs is small compared to that of the  radar’s total bandwidth, which improves the SNR.   • Velocity estimates can be made by mon itoring the power out of each filter. 
 FIQ. 16.35.—Signal circuits and case forthe line ofFig. 16.33; two-channel amplifier onthewide chassis atleft, video-modulated oscillator and amplifier onthe narrow chassis at right. 
 SCATTEROMETER 
 Medhurst, and S. D. Pool: Superdirectivity, Proc. 
 76. Brook, M., and P. Krehbiel: A Fast-Scanning Meteorological Radar, Preprints, 16th Conf. 
 Its 10 m by 1.3 m active array antenna com - prises 320 transmit/receive modules. In other regards, its modes reflect the basic  RADARSAT-1 design (due, in large part, to the participation by key radar specialists  from Canada—a member of ESA’s Earth Observation Program Board—on the ASAR  conceptual design team). The transmit and receive polarizations are independent of  each other, so that at full resolution, the polarization choices are HH, VV, or HV. 
 12  Radar Cross Section  ................................ ................................ ................................ 
 Radar information isparticularly useful because itgives accurate determinations ofrange; itisobviously sensible toprovide, as anadjunct toradar, the sort ofbeacon that makes the best use ofthis property. This chapter aims togive abrief r6sum6 ofthemain points involved intheuseofradar beacons. The design ofbeacons and ofsystems using them istreated atlength inVol. 
 The  observed quantities are usually the output power, the wavelength, and the anode voltage.  The problem of presenting the variation of the three quantities-power, wavelength, voltage-  as a function of the four parameters mentioned above is greatly simplified since the input and  output parameters operate nearly independently of each other. Thus it is possible to study the  effect of the magnetic field and the anode current at some value of load st!sceptance and  conductance chosen for convenience. 
 product). The problem of synthesizing optimum waveforms  from an ambiguity diagram specified by operational requirements is a difficult one and is often  approached by trial and error.  The name ambiguity function for I x(TR ,fJ) 12 is somewhat misleading since this fun,;tion  describes more about the waveform than just its ambiguity properties. 
 The use of a three-pulse canceler ahead  of the filter2bank eliminates stationary clutter and thereby reduces the dynamic range required  I ,Q 3-pulse  canceler  Zero velocity  filter 8-pulse doppler  filter bank  Magnitude Weighting  and  magnitude  r------- Clutter mop Thresholding  ,recursive _____ _,  filler  Memory  (clutter map) Hit report  Figure 4.27 Simple block diagram of the Moving Target Detector (MTD) signal processor. 128 INTRODUCTION TO RADAR SYSTEMS  of the doppler filter-bank. The fast Fourier transform algorithm is used to implement thl.!  doppler filter-bank. 
 Plonus, “Theoretical investigation of scattering from plastic foams,” IEEE Trans ., vol. AP- 13, pp. 88–93, January 1965. 
 34, pp. 335-348, Junc, 1946; also discrts-  siori by 11. J. 
 VA, III & VI, C.C.D.U. Trial Report No. 44/23, 25 March 1944 (TNA AIR 65/91) [18] Improved A.S.V. 
 Target Cross Section. The definition of radar target cross section that applies for use in the foregoing radar range equations is given in Chap. 11, and the reader is referred to that chapter for a detailed discussion of the subject. 
 Thenormalized radiation patternofthearraywhenthephasedifference between adjacent elements is<pisgivenby G(O)=sin2[Nn(d/l)(sin {)-sin00)] N2sin2[n(djA)(sin 0-sin00)] Themaximum oftheradiation patternoccurswhensin0=sin00, Equation (8.9)statesthatthemainbeamoftheantenna patternmaybepositioned toan angle00bytheinsertion oftheproperphaseshift<pateachelement ofthearray.Ifvariable, ratherthanfixed,phaseshiftersareused,thebeammaybesteeredastherelative phase between elements ischanged (Fig.8.2).. lfli: 1:l I.('IRONI('AI 1.Y STEERFI) P1fASFI) ARRAY ANTENNA IN RADAR 283  -_.-2 Figure 8.2 Steering of an antenna beam with  variable phase shifters (parallel-fed array).  IJsing an arpunlent similar to the nonscanning array described previously, grating lobes  ;tl1l'cilr ;it a11 ;111glc 0, wlic~lcvcr rllc dcllor~lirlator is zero, or wile11  li a grating lobe is perrliitted to appear at -90" when the main beam is steered to +90°, it is  found from the above that (1 = 112. 
 If an aircraft is within range,  then an echo is bound to be picked up by the receiver,  and by the usual direction-finding system of right-angle  aerials and comparison of signal strength it was thought  not to be impossible to plot bearing. As can be ima-  gined, this system was simple in theory, but in practice  it presented us with a number of snags, not the least  of which was the great waste of power in floodlighting a  vast area with pulses when we could effect a great  economy if we could beam the energy and make a  . 54 HOW RADAR WORKS  ‘searchlight’ of our radar rays. 
 Based on measurement data obtained by Goldstone-Apple Valley and Arecibo radio telescopes, an original time frequency grid mathematical model of pulsar emissions is created. Passive ISAR scenario, a space object’s geometry and a model of pulsar signals reﬂected from the space object’s surface are also described and graphically illustrated. A new range compression approach for ISAR imaging is suggested and demonstrated. 
 Two methods ofpresenting thedoppler information have been mentioned: the aura 1method (Fig. 16.3), and the A-scope method (Fig. 16.6). 
 TOR 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 SLC configuration is not efficient, because this leads to the maximum entropy or  autoregressive methods that, being nonlinear processing, have a high probability of  spurious peaks. 
 15.27. The peak filter response can be located arbitrarily in frequency by adding a linear-phase term to the filter coefficients. The total number of filters implemented to cover all doppler frequencies is a design option trading straddling loss at the filter crossover frequencies against im- plementation complexity. 
 M. Sherman, D. N. 
 R. Bean and R. Abbott, “Oxygen and water vapor absorption of radio waves in the atmo - sphere,” Geofts, Pura Appl. 
 The Mixer.-The mixer’ contains thecrystal. Ithas two sets ofinput terminals, one forthereceived signal and one forthelocal oscil- lator; the output signal goes tothe first stage ofthei-famplifier. The requirements tobemet areasfollows: (1)the crystal must bemade to appear asamatched load tothe incoming signal; (2)there must be 1Microwave Mizers, Vol. 
 Atallmicrowave frequencies, the skin effect confines thecurrent toamicroscopically thin layer ontheinner surface. Asthe dimensions ofthe waveguide areincreased, the frequency being fixed, propagation becomes possible bymodes—that is,byparticular types of“vibration” intheelectromagnetic field, other than thefunda- mental mode illustrated inFig. 11.9. 
 16. D. K. 
 MOUNTED '02 #HAPTER   OR A VERY LOW ALTITUDE AIRCRAFT /F COURSE  ONCE RADAR SIGNALS PENETRATE THE SURFACE  THE USUAL VOLUMETRIC ATTENUATIONS AND REFLECTIONS OCCUR !S WITH ANY '02  LARGE DYNAMIC RANGE IS REQUIRED  SINCE THE SIGNALS OF INTEREST MAY BE WEAKER THAN COMPETING RETURNS BY  D" OR MORE 2ADAR SOUNDING TO APPRECIABLE DEPTH IS POSSIBLE ONLY IN DRY MATERIALS SUCH AS LUNAR REGOLITH OR IN VERY COLD LOW 
 Pulse-modulated radarcan determine the distance to a target by measuring the time required for anextremely short burst of radio-frequency (r-f) energy to travel to the targetand return to its source as a reﬂected echo. Directional antennas are used fortransmitting the pulse and receiving the reﬂected echo, thereby allowingdetermination of the direction or bearing of the target echo. Once time and bearing are measured, these targets or echoes are calculated and displayed on the radar display. 
 If harmonic power output is a problem, excellent high-power microwave filters are practical. 2. Adjacent-band spurious noise: Problems of this type may occur from ad- jacent modes in CFAs or in TWTs, typically appearing a few percent above (in forward-wave tubes) or below (in backward-wave tubes) the desired operating band. 
 The bending or refracting of radar waves in the at- mosphere is caused by the variation with altitude of the index of refraction, which is defined as the ratio of the velocity of propagation in free space to the *The data tables, figures, and portions of the following discussion on corrections for atmospheric refraction were extracted from and follow closely the original text of Burt Brown's Chap. 22, "Radar Handbook," 1st ed., edited by Merrill Skolnik.10RADARAIRCRAFTTARGET EARTH SURFACE RADAR AIRCRAFTTARGET EARTH SURFACE . (d) FIG. 
 The sur-  it--- '0 +-to--- -+ I face reflection coefficient is p.  546INTRODUCTION TORADAR SYSTEMS reducetheangularerror.Theeffective receiving areaoftheinterferometer isusuallylessthan thatoftheconventional radarreflector antenna withwhichitisused.Thus,therangecapa­ bilityoftheinterferometer anglemeasurement mightbeJessthanlhat orthe2Dradar.This reduced rangecapability isacceptable inmanysituations sincetheheightmeasurement is usuallyofmoresignificance atshorterratherthanlongerranges. Loberecognition. 
 77. Woodward, P. M.: A Method of Calculating the Field over a Plane Aperture Required to Produce a  Given Polar Diagram, J. 
 LOOP  WHICH  OPERATE JUST ON THE INCOMING SIGNALS  6- AND 6 "ROADLY SPEAKING  CLOSED 
 The tradeoff between short gate length (thus lower processing yield) and insertion loss must be examined. (2) The value of the parasitic drain- source capacitance will affect the OFF-state isolation of the device. This capaci- tance depends largely on the source-drain spacing of the FET geometry. 
 By switching between the two beams and keeping the observed amplitudes equal, the SCR-268 eleva- tion operator could keep the antenna boresighted on the target accurately. If a dish antenna, which generates a narrow pencil-type beam in azimuth and elevation, is mechanically boresighted and trained at or in the vicinity of a target,FREE-SPACEANTENNAPATTERN AIRCRAFT TARGETMULTIPATH- LOBEDANTENNA PATTERN RADAR UPPERANTENNA LOWERANTENNAFREE-SPACE PATTERNOF ANTENNAS MULTIPATH-LOBED PATTERN OF LOWER ANTENNA MULTIPATH-LOBED PATTERN OF UPPER ANTENNA EARTH SURFACE . allowing determination of its azimuth and elevation, the technique is called searchlighting. 
 D. Friedle: Forward Scatter of Electromagnetic Waves  by Spheres. IRE WESCO N Com,. 
 Should themotor attain aspeed .-—. motor-alternator with Holtzer-Cabot speed control.. 578 PRIME POWER SUPPLIES FOR RADAR [SEC. 
 Also,agoodMTIiseasier10 achicvc andtheeffectsofwcather arclessatthesefrequencies. Thepreferred frequency range foranaircraft-tracking radaristheupperportionofthemicrowave band(CorXbands)since itiseasiertoobtainthewidebandwidths andnarrowbeamwidths forprecision targettracKing thanatthelowerfrequencies. Thustracking radarsdiffersignificanlly fromsurveillancc radars.Whenasingleradaristoperform hothsurveillance andtracking. 
 FREQUENCY PORTION OF THE SPECTRUM NOW APPEARS  ON THE RIGHT OF THE SAMPLED SPECTRUM AND DOESNT OVERLAP THE DARKER POSITIVE 
 It would seem a simple matter to characterize sea clutter empirically by direct measurement of radar returns for a wide variety of both the radar and environ- mental parameters that appear to affect it. Parameters relating to the radar or its operating configuration, such as frequency, polarization, cell size, and grazing angle, may be specified by the experimenter, but the environmental parameters are quite another matter—for two reasons. First, it has not always been clear which environmental variables are important. 
 POLARIZATION  4HE 3POT3!2 MODE REQUIRES YAWPITCH STEERING OF THE SPACECRAFT TO  on #OVERAGE  TO EITHER SIDE OF THE GROUND TRACK REQUIRES A ROLL MANEUVER OF THE SPACECRAFT TO DIRECT THE ANTENNA PATTERN TO THE OPPOSITE SIDE OF NADIR  AN APPROACH THAT IS SIMILAR TO THAT OF 2!$!23!4 
 The effects  of diffraction of energy by neighboring elements should also be considered as a mutual  coupling problem. This is especially noted with end-fire elements (such as polyrods or log­ periodic antennas) which are spaced close enough to couple or diffract energy. The effect of  mutual coupling on the input impedance with such elements is usually small. 
 "Ê-1**, 
 DOPPLER CELL IS COMPUTED 4HESE CALCULATIONS ASSUME A NOISE 
   ON 
 DOPPLER 34!0 ARCHITECTURES !S THE NAME IMPLIES  THE ANTENNA ELEMENT SIGNALS ARE FIRST DOPPLER FILTERED AND THEN PROCESSED THROUGH 34!0 4HE MOTIVATION FOR THIS TYPE OF ARCHITECTURE IS THAT THE RESULTANT 34!0 SOLUTIONS CAN INDEPENDENTLY ADDRESS A SUBSET OF THE CLUTTER INTERFERENCE PROBLEM ISOLATED TO CLUTTER  THAT REMAINS IN A  SINGLE DOPPLER FILTER  4HIS TECHNIQUE MAY BE MORE EFFECTIVE FOR RADAR  SYSTEMS WHERE THE CLUTTER ENVIRONMENT AND WAVEFORM SELECTION LEAD TO UNAMBIGUOUS  CLUTTER RETURNS WITHIN THE RADARS 02& 4WO EXAMPLE CONDITIONS  THE FIRST WITH AMBIGU 
 Now the bistatic clutter doppler returns skew and spread, depending upon the geometry for each clutter patch and the kinematics of the transmit and receive platforms. Doppler skew is defined in terms of isodoppler contours, or isodops, given by Eq. (25.18) for two dimensions and a flat earth. 
 10.12), each offset in frequency by an amount corre- sponding to a doppler resolution element which is the reciprocal of the expanded pulse length. The processing following the subpulse filter in Fig. 10.12 is then duplicated for each doppler channel. 
 If a phased array radar uses a feed- back canceler, many pulses may have to be gated out after the beam has been repo- sitioned before canceler transient ringing has settled to a tolerable level. An initial- ization technique has been proposed20 to alleviate this problem, but it provides only partial reduction in the transient settling time. If feedforward only is used, only three or four pulses have to be gated out after moving the beam. 
 TRACKING OR hBATCHv ALGORITHMS  CONSIDER ALL THE DETECTIONS SIMULTANE 
 Time sidelobes and weighting. The uniform amplitude of the linear FM waveform results in a  compressed pulse shape of the form (sin nBt)/nBr after passage through the matched filter, or  dispersive delay line, where Bis the spectral bandwidth. 24 There are time, or range, side lobes  to either side of the peak response with the first, and largest, side lobe -13.2 dB down from the  peak. 
 Figure 19: Decreased maximum range by defect or missing power modules in a solid state  transmitter with 32 power modules  . Radartutorial (www.radartutorial.eu)   15  max22 4 34MDStx t sPGR PL     MDS - Echo   The minimum discernible signal is defined as the useful echo  power at the reception antenna, which gives on the screen a  discernible blip. The minimum discernible signal at the receiver  input -jack leads to the maximum range of the radar ; all other n ominal variables are considered as  constant. 
 NOISE RATIO OF A SINGLE PULSE  ASSUMING ALL PULSES HAVE EQUAL AMPLI 
  53 !RMY  !2  
 It will be assumed that the phase distribution  across the aperture is constant and only the effects of the amplitude distribution need be  considered.  The inverse Fourier transform gives the electric field intensity when the phase and ampli­ tude of the distribution across the aperture are known. The aperture is defined as the projec­ tion of the antenna on a plane perpendicular to the direction of propagation. 
 DOPPLER SCATTEROMETER . 
 In some instances, there might be partial correlation of the pulses within a scan  (rnoderate fluctuation). Sch~artz~~ considered the effect of partial correlation for the case of  two ~l~ilqcs per scar] (11 = 2). The results for partial correlation fall between the two extremes of  cotlll~lctcly iir~cor related and cor~~plctcly correlated, as nligllt be expected. 
 Theamountofnoisewhichenterstheantenna depends upontheentireantenna radiation pattern, including thesidelobes andthetypeofobjectstheyilluminate. Landisalmosta complete absorber; hencethoseportions oftheradiation patternwhichilluminate theground seeanoisesourceattheambient temperature. Perfectly reflecting sources,suchasasmoothsea ../ oraroad,actasamirrortoreflectthe'nidiation fromtheskyorotherobjects.Thustheseaor ametallic objectmayappearverycoldifitisoriented toreflectradiation fromtheskytothe antenna. 
 The opening and closing may result from the waveform applied toone oftheelectrodes, asinarectifier oradetector, orone oftheelec- trodes may bechanged inpotential from time totime byaseparate impulse. The useofdiodes forswitching purposes hasbeen rendered more attractive bytheadvent ofthegermanium-crystal type ofrectifier, which admirably replaces the vacuum-tube diode inmany applications, par- ticularly those involving 50volts orless ofback emf. The D-cRestorer. 
 They have been designed for remote  operation in harsh environments, and with their established logistics support, built-in  performance monitoring and fault isolation, high reliability, and worldwide invest - ment, these systems have an inherent low cost of ownership. Northrop Grumman Corporation Phased Array Radars.  (Courtesy of  Northrop Grumman Corporation ) AWACS (Airborne Warning and Control System).13,14,115 The Airborne Warning  and Control System (AWACS) provides all-weather long-range surveillance, com - mand, control, and communications. 
 Both antennas  have a " tunnel " around the periphery for further shielding.  Additional isolation can be obtained by properly introducing a controlled sample of the  transmitted sig:ial directly into the receiver. The phase and amplitude of this " buck-off" signal  are adjusted to cancel the portion of the transmitter signal that leaks into the receiver. 
 With linearly polarized radiation, Faraday rotation will result in a polarization mismatch varying with time and distance. That is, the target-incident-energy polarization will rotate as distance changes. Since many targets have RCSs that vary with polarization, an important result is that the most favorable polarization will illuminate the target recurrently. 
 However, for small ratios of doppler frequency to radar bandwidth, good doppler response can be obtained for reasonable target velocities. Lewis and Kretschmer34 have rearranged the phase sequence to reduce the degradation that may occur by receiver band limiting prior to pulse compression. The rearranged phase sequence is 4>,, = f[l-/> + ^] forPodd . 
 Since the IPL is signiﬁcantly longer than the ionospheric coherent length, the P-band sliding spotlight mode will deﬁnitely be inﬂuenced by ionospheric irregularities. In Li’s work, the SAR resolution is deﬁned as the absolute range separation δr=/bardblr−r0/bardblby using the criterion of ambiguity function, which is expressed as /angbracketleftBig |χ(r,r0)|2/angbracketrightBig/slashBig/angbracketleftBig |χ(r0,r0)|2/angbracketrightBig =exp(−2) (12) 189. Sensors 2019 ,19, 2161 However, the redeﬁned SAR resolution in GAF model dose not conform to the general concept of the SAR resolution based on the −3 dB criterion. 
 B. Goode: Adaptive Antenna Systems. Pro'.. 
 Radar Conf ., 1995, pp. 692–697. 21. 
 PERFORMANCE RADAR KLYSTRONS TEND TO EMPLOY THE MORE INTRICATE CAVITY STRUCTURE BECAUSE OF THE BETTER PERFORMANCE IT PROVIDES #OMPARISON OF 6ARIOUS ,INEAR 
 -  -ODERN MULTIFUNCTION PULSE DOPPLER RADARS UTILIZE VARIOUS MODES TO ACCOMPLISH TASKS SUCH AS SEARCH AND TRACK %ACH MODE USES CERTAIN WAVEFORMS OPTIMIZED FOR THE DETEC 
 20.2 (Continued) Exemplar 3D radars, (c) AN/FPS-117 fixed-site solid- state phase-scanned 3D radar (Courtesy General Electric Company). Digital Beamforming Radar. A technology with considerable attractiveness for radar is digital beamforming. 
 CONTROLLED TUBE )T IS CUSTOMARY TO THINK OF THE SHAPE OF A CONVENTIONAL RADAR PULSE AS BEING  RECTANGULAR )T IS SELDOM  HOWEVER  PERFECTLY RECTANGULAR WITH VERY SHORT RISE AND FALL TIMES BECAUSE SUCH A WAVEFORM HAS A VERY LARGE BANDWIDTH  AS ONE CAN OBSERVE FROM ITS &OURIER TRANSFORM %VEN IF A LARGE BANDWIDTH WERE AVAILABLE TO SUPPORT A . £ä°ÓÓ  2!$!2 (!.$"//+  RECTANGULAR PULSE  A LARGE BANDWIDTH WOULD LIKELY CAUSE INTERFERENCE TO OTHER RADARS  AND OTHER ELECTROMAGNETIC SYSTEMS &OR THIS REASON  GOVERNMENT FREQUENCY ALLOCATION AGENCIES USUALLY REQUIRE THAT THE FREQUENCY SPECTRUM FROM A RADAR NOT CONTAIN LARGE ENERGY AT OTHER FREQUENCIES 4HIS IS BECOMING MORE IMPORTANT AS THE OCCUPANCY OF THE ELECTROMAGNETIC SPECTRUM IS INCREASINGLY CROWDED WITH TRANSMITTERS 4HE CLASSICAL WAY TO REDUCE THE FAR 
 They have had application in military range finders and in distance measurement for surveying. They have been considered for use from space for measuring profiles of atmospheric temperature, water vapor, and ozone, as well as measuring cloud height and tropospheric winds. Lasers are not suitable for wide-area surveillance because of their relatively small physical aperture area. 
 POWER BEAMWIDTH  WHICH CAN BE APPROXIMATED BY  KA  A BEING THE EFFECTIVE  HORIZONTAL APERTURE WIDTH 4HUS   E6 AX 
 C  C  -~ ~10 - 0  D  0  L  ';; -15 -...  0  OJ RADAR ANTENNAS 237  rr ·· ?U _l __ __L __ L_~ __ ..___~-~-~~- -100 -BO -60 --40 -20 0 20 40 60 80 100  8. degrees off axis  FiJ?ure 7.7 Radiation pattern of 0.84,l-diameter circular-waveguide aperture. 
 TEMS WERE EXCLUSIVELY PASSIVE  SUCH AS THE , 
 DELAY THREE 
 We can control the electron speed, within limits, by the  applied voltages, and it will be realized that if we control  the electrons to travel with the speed of light, then the  distance travelled in one time period would be equal to  the wavelength of the applied oscillation. If the wave-  length is only 3 centimetres, then obviously this bears  relation to the physical dimensions of the valve itself.  We can, in fact, work out the distance travelled by  electrons when sped on by a variety of voltages, and we  find that at a wavelength of Io centimetres the distance  travelled in one time period is 2 millimetres for an elec-  tron urged on by 100 volts. 
 94 INTRODUCTION TO RADAR SYSTEMS  The Janus system can be operated incoherently by using the same transmitter to feed a  pair of beams simultaneously. Typically, one beam is directed ahead and to the right of the  ground track, and the other aft and to the left. A forward-left and an aft-right are also fed by  the transmitter as a second channel. 
 FILL 
 • The increasingly rapid attenuation of propagation to ranges beyond about 200 km,  as shown in Figure 20.40, means that at longer ranges, relatively little detection  performance improvement is gained by large increases in transmitted power. • The rate of decay of the surface waves rises sharply with increasing frequency, as  shown in Figure 20.40, whereas the RCS of small targets tends to increase rapidly  and external noise decreases. It follows that radar design is sensitive to the classes  of targets to be detected. 
 The presence of extended ranges cannot always be predicted in advance.  Furthermore, they cannot be depended upon. The extension of range along some propagation  paths means a decrease of range along others, or radio holes. 
 RAYS THAT ARE GENERATED )N A KLYSTRON  THE POWER AVAILABLE FOR CONVERSION OF THE DC POWER OF THE ELECTRON BEAM TO 2& POWER OF AN ELECTROMAGNETIC WAVE IS GIVEN BY THE PRODUCT OF THE BEAM CURRENT AND THE BEAM VOLTAGE  !LTHOUGH  KLYSTRONS HAVE BEEN OPERATED AT VERY HIGH VOLTAGES  IT IS USUALLY PREFERRED TO OPERATE IT AT A LOWER VOLTAGE  IF POSSIBLE  BECAUSE LOWER VOLTAGES GENERALLY MAKE THE POWER SUP 
 it was shown that the fading is strongly  dependent on tlie radar and the target heights, and that for centimeter wavclcngtlls tlic lading  occurs at intervals of from two to three miles.  Tlie lieight of the evaporation duct. from wliich the propagation conditions can bc in-  ferred, can be readily calculated from measurements of the surface water tem pcrat ure and, at  some convenient height, the air temperature, relative humidity, and wind ~peed.~"TIiese four  measurements have been found sufficient for the description of ducting conditions. 
 471–476, 1985. 15. S. 
 Two different focal  lengths are used in the reflector, one for  elevation and a longer one for azimuth.  The feed is on a curved surface, opti - mized via ray tracing, and is forward of  the azimuth focal point. For each row,  the amplitude and phase is optimized for  a beam with low azimuth sidelobes. 
 The pulses from the two modulators are transmitted through rotary joints. All FIG. transitic put bus front.1 1; i]31 (c) ng;.—T mah (f)‘ran ~net pulsmitter compartment, shipborne radar: (a) magnet ron cathode bushing; (d) desp]king resistor; (e)pulse setransformer case, directional coupler ofOPPOS;(b) ‘.’doork] -transformer ite transmitt10b ‘‘ Out- erin other power, signal,and cent rolconnections tothe rotating turret are made viaslip rings. 
 16.3 Loci of constant normalized radial velocity VJV9 as a function of aircraft range-to-height ration RIH and azimuth angle v|/. Effect of Slant Range on Doppler Offset. The antenna boresight velocity VB is the ground-velocity component along the antenna centerline (boresight) and is given as -V8 cos a0. 
  RADAR TRANSMITTER v  -ICROWAVE *  VOL   PP n  *ULY   * 7 4AYLOR  *R AND ' "RUNNIS  h$ESIGN OF A NEW AIRPORT SURVEILLANCE RADAR !32 
 When there is a multipath signal present along with the direct  signal, a quadrature component of the difference signal exists. The in-phase and the quadra-  ture components of the error signal define a complex angle-erro-F-sign&. In the complex planc,  with the in-phase and quadrature components as the axes, the locus ofthe complex angle with  target elevation as the parameter is a spiral path. 
 ch11.indd   25 12/17/07   2:25:35 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 
 ON ASPECTS  AS WELL AS IN THE BROADSIDE  REGIONS  OF BODIES BOTH FAT AND THIN 4HESE NEAR 
 With a user-specified antenna type, the opera - tor may enter the pattern angle and factor directly. In addition to entering the antenna  pattern directly from the keyboard, AREPS also provides the capability of importing  an antenna pattern from an ASCII text file that you may have created from another  application. An example of multiple units is the transmitter’s peak power. 
 To illustrate the RCS behavior of a typical aircraft in more detail, Figure 20.9  shows the RCS of the F-18 fighter, as computed here by NEC2 applied to a wire- grid representation of the aircraft derived from a plastic kit model. The RCS shown  is for monostatic (backscatter) geometry and horizontal copolar (HH) polarization.  Calculations are presented for frequencies of 12, 18, and 30 MHz. 
 As a second step, the quality of a CFAR threshold considering a scenario without targets or  clutter, implying a pure Rayleigh -distributed background (resulting in the parameter -settings α  > 0 and β = 0) is evaluated. A criterion for the quality of a CFAR threshold is then given by  the so- called CFAR- loss (LCFAR), defined in [3] as LCFAR [dB] = 20 log10 (E(TC) / TWC), where  TWC is the fixed threshold without CFAR, dependent on the false alarm probability (Pfa), and  E(TC) is the mean -value of the CFAR threshold, also Pfa-dependent.      Figure 12.15  CFAR -Loss LCFAR. 
     !.&03 
 At the same time, a 3 cm version of ASG, AN/APS-15, was being developed in the USA. This radar was designed as an X-band H 2Sa n d was considered unnecessarily complic ated for ASV use. It was agreed that 100 Liberator GR Mk. 
   6OL  .ORWOOD  -! !RTECH (OUSE  )NC    PP n  2 , -ITCHELL  2ADAR 3IGNAL 3IMULATION  #HAPTER   .ORWOOD  -! !RTECH (OUSE  )NC    * + *AO AND 7 " 'OGGINS  h%FFICIENT  CLOSED 
 The length of the maximal sequence is N = 2n — 1, where n is the number of stages in the shift-register generator. The total number M of maximum-length se- quences that may be obtained from an n-stage generator is M = Vl-I)n \ Pi/ where p{ are the prime factors of N. The fact that a number of different sequences exist for a given value of n is important for applications where different se- quences of the same length are required. 
 If the jammer-to-signal ratio (JIS) decreases to the point that skin track is again possible, this is given preference over HOJ. Also, provision must be made to allow switching between HOJ and skin if the jamming is intermittent. The criterion in all cases is that the mode which provides the better quality of guidance information should be given precedence. 
 9. Special Issue on electronic warfare, IEE Proc ., vol. 129, pt. 
 The setting up of the sets by the RAF maintainers seems to have been a particular problem, due to lack of experience in diagnosing faults and tuning the equipment on the ground. The trials measured the detection performance of the radars asmaintained by the RAF and the same sets were then set up by TRE personnel and re-tested. In the worst example, one radar ’s detection range against Lundy island improved by 360% after tuning by TRE and another radar improved by 70%.A range increase of 360% is equivalent to about 26 dB of improvement in sensitivity. 
 ,6 
 J. Griffiths, and B. B. 
 IEEE , vol. 54, pp. 633–640, April 1966. 
 J. Sletten. W. 
 Considerable progress toward anunder. standing ofthe phenomenon has now been made, 1and when mode. 1F.F.Rieke andR.Fletcher, “Mode Selection inMagnetrons, ”RLReport No. 
 TUNED LOAD 4HE NET RESULT IS HIGH AMPLIFIER EFFICIENCY 4HE PRACTICAL IMPLICA 
 One ofthese isa geometrical factor that expresses the effects ofinterference and diffrac- tion. The other takes account oftheattenuation oftheradiation inthe atmosphere. These matters asthey pertain toradar echoes are dis- cussed inSees. 
 Obviously, the receiver should be  designed to generate as little internal noise as possible, especially in the input stages where the  desired signals are weakest. Although special attention must be paid to minimize the noise of  the input stages, the lowest noise receivers are not always desired in many radar applications if  other important receiver properties must be sacrificed. ,  Keceiver design also must be concerned with achieving sufficient gain, phase, and ampli-  tude stability, dynamic range, tuning, ruggedness, and simplicity. 
 Unfortunately, recognition is limited to broad categories rather than MIG-29M2  versus MIG-29S (even though there are significant differences that air show visi - tors can easily see89). The basic notion of doppler, resonances, stepped (SFWM), and multifrequency  (MFR) signatures is modulation either by reflections from moving parts, e.g., engine  compressor, turbine, rotor, or propeller blades, or by interactions from scatterers along  the aircraft or vehicle, e.g., fuselage, wing, antennas, or stores. SFWM/MFR signa - tures are closely related to high range resolution signatures (a Fourier transform easily  converts one to the other), and they suffer the same attitude estimation limitations. 
 Alarge measure ofgratitude mustbeexpressed tothoseradarengineers whohavetakenthetimeand energytoensurethattheresults,oftheirworkweremadeavailable bypuhlication in recognized journals. '. Onamorepersonal note,neithereditionofthisbookcouldhavebeenwrittenwithout th~ complete support andpatience ofmywifeJudithandmyentirefamilywhoallowed methe timenecessary toundertake thiswork. 
 Under certain conditions, bending ofthe microwave beam around the earth isproduced bymeteorological conditions (Sec. 2.14). This can increase the range ofaradar setbeyond the optical horizon, but such phenomena arerelatively rare and essentially unpredictable. 
      (n n  
 Krichbaum:" Radar Cross-Section Handbook," (2  vols.), Plenum Press, New York, 1970.  20. Siegel. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar.  PULSE COMPRESSION RADAR  8.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 Clutter rejection with pulse compression waveforms is due to the greater range reso - lution achievable over uncoded waveforms. 
 188-190, February, 1954.  5. Greenwood, I. 
 Gogineni, D. Tammana, D. Braaten, C. 
 pp. 312-317.  28. 
 529–534, July 1991. 164. W. 
  
 NOISE LEVEL THAT CAN BE PROCESSED LINEARLY  IS RELATED TO THE NUMBER OF AMPLITUDE BITS IN THE !$ CONVERTER BY   3 .. MAXLOG;=§ ©¨¶ ¸· 
 76. Hubbard, J. V.: Digital Automatic Radar Data Extraction Equipment, J. 
 et al; Microwave remote se nsing, active and passive (Band 1 -4);  Addison-Wesley; 1981; UB- Ka [88A762]  − Maurice W. Long Ph. D.,, Radar Reflectivity of Land and Sea, Hardcover 400 Seiten,  ISBN 0.89006.130- 6, 1983  − Sherman, S.; Monopulse Principles and Techniques; Artech House; 1984    − Mensa, D.L; High Resolution Radar Imaging; Artech House; 1982; UB- Ka  [82A2418]  − Swerling, P.; Probability  of detection for fluctuating targets; IRE Trans.; Vol. 
 In later versions of the radar the received signals were not attenuated. Figure 4.5. Attenuator type 53, general view of hardware [ 8]. 
 The results depicted in Figs. 2.3 through 2.7 apply for perfect postdetection (video) integration of a specified number of pulses. It was shown by North2 that under ideal conditions predetection integration results in the smallest possible detectability factor and that for ideal predetection integration of M pulses the following relation holds: D0(M) = D^l)IM (2.27) That is, the minimum detectable signal-to-noise power ratio at the demodulator input terminals is improved, relative to single-pulse detection, by a factor exactly equal to the number of pulses integrated, M. 
 LAW DETECTOR SEE &IGURE   4HE COLLAPSING LOSS IS THE ADDITIONAL  SIGNAL REQUIRED TO MAINTAIN THE SAME  0$ AND 0FA WHEN UNWANTED NOISE SAMPLES ALONG  WITH THE DESIRED SIGNAL 
 £Î°Èn  2!$!2 (!.$"//+  4ERMINAL (IGH !LTITUDE !REA $EFENSE 4(!!$   4(!!$ IS A GROUND 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.4 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 is also used as a phase reference for determining the phase of reflected signals. The  phase information is stored in a pulse repetition interval (PRI)) memory for the period,  T, between transmitted pulses, and is subtracted from the phase information from the  current received pulse. 
 All rights reserved. Printed in the United States of America. Except as permitted under the Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of publisher. 
 DAY REPEAT ORBIT FIRST USED WITH 3EASAT DATA TO PROVE THE CONCEPT AND  FOR STABLE TERRAIN FEATURES  SUCH AS UNVEGETATED ROCKY MOUNTAIN SLOPES )T IS NOT NECES 
 pp. 745-753. June. 
 BAND CIRCUITS  WHICH WERE RELATED TO THE TYPE OF CIRCUITS USED IN 474S 3UCH KLYSTRONS ARE KNOWN AS THE #LUSTERED #AVITY +LYSTRON  %XTENDED )NTERACTION +LYSTRON  AND THE 4WYSTRON 7HEN CONSIDERING A TRANS 
 LATITUDE n  . AND 3 LATITUDE  FLYING IN A  KM ALTITUDE ORBIT AND USING DUAL  WAVELENGTH PRECIPITATION RADAR $02   AT +U AND +A BANDS FOR MORE ACCURATE RAINFALL  ESTIMATES USING ATTENUATION TECHNIQUES  4HE TWO RADARS WILL HAVE MATCHED BEAMS  FROM TWO SLOTTED WAVEGUIDE ARRAY ANTENNAS AND PROVIDE COVERAGE UNDER THE SPACECRAFT TRACK SIMILAR TO 42-- #LOUD3AT IS A SATELLITE LAUNCHED IN  FLYING A 7 BAND  MM  CLOUD PROFILING  RADAR #02  ORBITING THE %ARTH IN A SUN SYNCHRONOUS ORBIT AT AN ALTITUDE OF ABOUT   KM  4HE TRANSMITTER IS AN %XTENDED )NTERACTION +LYSTRON %)+  HIGH 
 618.TABLE   9.2  Inventory of Angle-Error Components* ch09.indd   44 12/15/07   6:08:00 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 
 Soc., vol. 88,  pp. 485-495. 
 6. Lerner, R. M.: A Matched Filter Detection System for Complicated Doppler Shifted Signals,  pp. 
 Equipment considerations. The synthetic-aperture radar requires a coherent reference signal  and means for storing and processing the radar echoes. The coherent reference is necessary  since an angle measurement is a measurement of phase from spatially separate positions. 
 The term "reflection  coefficient" as usually found in the literature is generally that of the coherent component. The  incoherent, or fluctuating, component of a surface-scattered signal is characterized by a  random phase and amplitude. The incoherent component of the forward-scattered signal from  a rough surface behaves differently from the coherent component as a function of roughness. 
 DELAY CIRCUITS IS VERY HIGH FOR MOST PRACTICAL SYSTEMS 4HEY WOULD  THEREFORE  PRECEDE A FINAL POWER AMPLIFIER FOR TRANSMITTING AND FOLLOW A PREAMPLIFIER FOR RECEIVING ! FURTHER METHOD OF PROVIDING DELAY IS POSSIBLE BY TRANSLATING THE PROBLEM FROM THE  MICROWAVE DOMAIN AND DELAYING AT )& &)'52%   4IME 
 Coleman25.1 25.1  Introduction / 25.1 25.2  Receive Channel Processing / 25.2 25.3  Transmit Channel Processing / 25.20 25.4  DSP Tools / 25.22 25.5  Design Considerations / 25.34 25.6  Summary / 25.37   Acknowledgments / 25.38.     xii Chapter 26 The Propagation Factor, F p, in the Radar Equation Wayne L. Patterson26.1 26.1  Introduction / 26.1 26.2  The Earth’s Atmosphere / 26.2 26.3  Refraction / 26.3 26.4  Standard Propagation / 26.4 26.5  Anomalous Propagation / 26.6 26.6  Propagation Modeling / 26.13 26.7  EM System Assessment Programs / 26.18 26.8  AREPS Radar System Assessment Model / 26.23 26.9  AREPS Radar Displays / 26.25 Index 1.1. 
 MUM 02& SHOULD BE  K(Z  YET  IT WAS  K(Z IN PRACTICE 4HE  PULSE RATE ABOVE THE  THRESHOLD IMPROVED THE ADDITIVE 3.2  BUT DID NOT CONTRIBUTE TO SPECKLE REDUCTION 4HE 02& STATISTICAL INDEPENDENCE LIMIT DECREASES WITH INCREASING SIGNIFICANT WAVE HEIGHT *ASON 
 Cheston, Naval Research Laboratory (CHAPTER 7) L. J. Cutrona, Sarcutron, Inc. 
 The filtered sideband serves the function of the local  oscillator.  When an echo signal is present, the. output of the receiver mixer is an IF signal of  frequency fir + f,,, where f,, is composed of the range frequency fr and the doppler velocity  frequency f4• The IF signal is amplified and applied to the balanced detector along with the  local-oscillator signal .fiF. 
 1 CAVITIES WITH 1S OF ONE HALF TO ONE THIRD OF THE SINGLE CAVITY THEY REPLACE   &IGURE  COMPARES SCHEMATICALLY THE BASIC DIFFERENCE BETWEEN THE CONVENTIONAL STAGGER 
 However, the attenuation even inthebest dielectric, asseen inTable 11~1,begins tobeserious at10cmand gets worse atshorter wavelengths. Substitu- tion ofairforthesolid dielectric eliminates dielectric losses, and only the much smaller conductor losses remain. But the center conductor must somehow besupported mechanically. 
 Martel, M. Philippakis, and D. J. 
 For a three-pulse  version of this architecture, there are 3M degrees of freedom. In this architecture,  platform motion compensation takes the general form of adjusting the antenna’s phase  center over the three temporally separated beams. A basic block diagram of a radar incorporating pre-doppler, elemental-level space- time adaptive array processing is shown in Figure 3.25. 
 RADAR DIGITAL SIGNAL PROCESSING  25.396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25  6. B. Brannon and A. 
 M. Gray, F. Hutchinson, D. 
 (12.4) must be appropriately modified to  account for the actual antenna radiation pattern. Theoretically, the nulls in the lobe structure  are at zero field strength since the direct and reflected signals are assumed to be of equal  amplitude. In practice, the nulls are "filled in" and the lobe maxima are reduced because of  nonperfect reflecting surfaces with reflection coefficients less than unity. 
 The proper d-clevel fortheswitching signal can usually bechosen byaproper choice ofR,,R,,and the bias potential. Ifnot, itmay be necessary touse condenser coupling and ad-crestorer onthe cathode- follower grid. The corresponding negative clamp isnot used, since the circuit ofFig. 
 Instabilities due to PM (of which FM is a special case) tend to dominate those  due to AM. As such, the focus will be on phase disturbances: random phase noise and  discrete sinusoidal signals (spurious signals). Random Phase Noise . 
 Sensors 2019 ,19, 252 40 s [ 8,9]. However, further reducing this time by using a mechanical scan, could result too demanding both in terms of power consumption and system operation. Installation and maintenance are other important aspects to consider in the overall assessment of a monitoring system. 
 ARRAY ANTENNAS v  )%%% 4RANS    VOL !0 
 126 LIMITATIONS OFPULSE RADAR [SEC. 4.4 The reader may well ask whether aphenomenon has been overlooked which could beused todistinguish some targets from others. There appears tobenopossibility forsuch aphenomenon inthe elementary process ofreflection ofelectromagnetic waves from inhomogeneities inthe medium through which they travel. 
 FILE IN MODERN AIRCRAFT IS AUTOMATIC BECAUSE A HUMAN PILOT DOES NOT HAVE THE REFLEXES TO AVOID ALL POSSIBLE DETECTED OBSTACLES )N TERRAIN AVOIDANCE 4!   THE ANTENNA SCAN IS IN A HORIZONTAL PLANE SHOWN IN THE  UPPER LEFT OF &IGURE   3EVERAL ALTITUDE PLANE CUTS ARE ESTIMATED AND PRESENTED TO  &)'52%  4&4! MODE EXAMPLE ADAPTED COURTESY 3CI4ECH 0UBLISHING  .   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°Ó THE PILOT ON AN AZIMUTH 
 (a)Illuminated areaof clutter. (b) Contributions tosignal: fixed clutter =R,;moving clutter =Rz;result- ant signal =R;resultant for next pulse = R’;variation between pulses =r.motions oftrees inthecase ofground clutter. The ground-clutter pattern may include strong echoes from sin- gle targets, especially inregions where there arelarge structures hav- ing simple geometric alshapes. 
 10.8  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 The chief motivation for the multiple-beam klystron is the efficient generation of  high RF power at a lower voltage than in a conventional klystron. Because of its lower  voltage (two or three times lower), an MBK can be more compact, have a lower magnet  weight (up to ten times less), be of lower weight and volume, generate less X-rays, have  high electronic efficiency (up to 65 percent), and have the potential for a higher instan - taneous bandwidth than does a conventional klystron.9 The lower voltages at which  they operate result in power supplies that can be simpler, lighter, cheaper, and more  reliable. The MBK can have a high output-power-to-weight ratio that might be two  to three times greater than that of an equivalent single-beam klystron. 
 /   PP n   &EBRUARY   2 % 6ANDER 3CHURR AND 0 ' 4OMLINSON  h"ISTATIC CLUTTER ANALYSIS v $ECISION 
 257-263, May 1984. 70. Peterson, A. 
 Ship surveillance with TerraSAR-X. IEEE T rans. Geosci. 
 Control centers are, therefore, located atsites chosen fortheir operational convenience, whereas radar locations arechosen mainly forterrain and coverage reasons. Sometimes itisdesirable tocollect the data atgreat distances from one ormore fixed land stations. Advantages are also gained byobtaining thedata atanairborne sitewith itsextended horizon, but displaying and using the data onthe ground oronaship. 
 Signal Process. 2016 ,29, 119–135. [ CrossRef ] 8. 
 SCAN IS A MEASUREMENT AT A SINGLE FIXED POINT IN SPACE AND IS DISPLAYED IN AMPLITUDE  Y  AND RANGE  X  ! " 
 SPACE PROPAGATION LOSS GIVEN BY %Q  AND  ,D" IS THE PROPAGA 
 As one goes to higher radar frequency,  the physical size of antennas decrease, and in general, it is more difficult to generate  large transmitter power. Thus, the range performance of radars at frequencies above  X band is generally less than that of X band. Military airborne radars are found at Ku  band as well as at X band. 
 Mooney: Multiple High-PRF Ranging, Proc. IRE Conf. Mil. 
 The design of a thinned array consists of selecting the diameter of the aperture to give the  desired beamwidth, selecting the number of elements to give the desired gain (gain is directly  proportional to the number of elements), and arranging the elements to achieve some desirable  property of the side lobes, such as minimizing the peak sidelobe or approximating some desired  radiation pattern. There have been many methods proposed in the literature for determining  the element spacings (or locations within the aperture) of such arrays. Only two will be  mentioned here: dynamic programming and density tapering. 
 The echo return from a complex target differs from that of a point source by the  modulations that are produced by the change in amplitude and relative phase of the  returns from the individual elements. The word modulations  is used in plural form  because five types of modulation of the echo signal that are caused by a complex target  affect radars. These are amplitude modulation, phase front modulation (glint), polar - ization modulation, doppler modulation, and pulse time modulation (range glint). 
 A moderate amount of leakage entering the receiver along with the echo  signal supplies the reference necessary for the detection of the doppler frequency shift. If a  leakage signal of sufficient magnitude were not present, a sample of the transmitted signal  would have to be deliberately introduced into the receiver to provide the necessary reference  frequency.  There are two practical effects which limit the amount of transmitter leakage power which  can be tolerated at the receiver. 
 The solution of the wave equation for the infinite, perfectly conducting circular cylinder can be resolved into two cases, one each for the incident electric or mag- netic field parallel to the cylinder axis. The expressions are slightly simpler than Eq. (11.6) and involve cylindrical Bessel functions of the first and second kinds.23 Fig- ures 11.20 and 11.21 illustrate the backscattering behavior for the two principal po- larizations as a function of the electrical circumference of the cylinder. 
 TO 
 a single long section of toroid is used that is capable of providing the total dilTerenlial  phase shift of 360". The required digital phase increment is obtained by operating on a minor  hysteresis loop. as in Fig. 
 The aperture illuminations for high values of ii are peaked at the center and at the edge  of tlic aperture. and tniglit be difficult to achieve in practice.  Care must be exercised in the selection of the sidelobe level of a Taylor pattern. 
 15.13 perature of50”C, and must withstand anhour’s operation at71”C. At thesame time, because ofthelow temperatures athigh altitude, theset must work satisfactorily at–55”C. Severe vibration and shock areencountered inaircraft, and some of the weight ofanairborne radar must bespent onadequate shock- isolating mountings. 
 10 tlic i~iiagitig of rot;ltirig t;isgcts.' cspcci;tlly tlic rnoon and planets.15 Figure 14.7 shows a  r igid hody I ot;itirig at :ill arigular. speed of (11, radians per second, wit11 the axis of rotati011  riorrn;~l to tlic p:1per. 'I'lic ctopplcr frccli~ericy associatcd witti a point P on the body located :I  distarlce r fro111 tlic axis of rotation is  where I. 
 Many variations ofthis circuit, mostly simplifications, have been used. For example, ifonly afew markers are required oneach pulse cycle, Vzcan beomitted, since thehigh-Q coils inthe oscillating circuit IT TJ2 L,, +300V -4Negative square wave1M 22kinput2W 0.1 6SN7 o-l --- r39k 2W & wEquallyspacedtimelnd[ces‘Utput FIG.13.38.—Switched generator formultiple time indices. will ring with sufficient amplitude forseveral cyc,les. 
 Therefore, as a general rule, pencil-beam height finding radars and elevation- tracking radars cannot be expected to produce reliable elevation-angle data when their beams are pointed within about one beam width (-3 dB beam width) above the ground. At larger elevation angles, the magnitude of the elevation errors is a direct function of the ground-reflected relative field strength received in the respective negative-angle elevation sidelobe (i.e., the product of the relative sidelobe level and the ground-reflection coefficient). Radar systems that employ a simultaneous amplitude comparison technique for target elevation-angle determination derive the elevation angle inside the ra- dar beamwidth by measuring the ratio of simultaneous signal returns on two squinted received beams after having illuminated the target in some manner. 
 33 -     4HE SIGNAL 
  
 The important point is that the numbers donot differ byorders ofmagnitude. Itmust be said, however, that itisnotalways easy tomake fulluseontheindicator ofthe information available inthe radar system (cf. Sees. 
 Klooster: Coherent Optical Processing or Synthetic Aperture Radar  Data, Proc. Soc. Plwto-Optical Instrumental ion Engineers, vol. 
 The unique problems of clutter ambiguities, eclipsing, range determination, etc., are the same as described in Chap. 17 and will not be repeated here. A key point is that the active seeker is a monostatic radar, whereas the semiactive system is bistatic. 
 FIELD POWER DENSITY OF A CURRENT ELEMENT  RADIATING INTO FREE SPACE               &)'52%   !NTENNA AND FEED GEOMETRY OF LOADED 4%- HORN   ,     CM #OURTESY )%%  . Ó£°Îä  2!$!2 (!.$"//+  4HE PREDICTED AND ACTUAL TIME 
 60, pp. 1551-1552, December 1972. 36. 
 Atgreaterranges(eleva­ tionangleslessthanabout0.8beamwidth), wherethean'tenna mainbeamilluminates the surface,theinterference between thedirectandthereflected signalscanresultinlargeerrorsin elevation angle.Theangular excursions canbeup(intotheair)ordown(intotheground). The peakerrorsaresevereandcanbemanytimestheangularseparation between thetargetandits"'.-..,,,,,,, RadarAntenna beam--------_-._- t1-._.---'.,- ~Directpath'fj~~ ~........::.:::: Target~-----~~----~ -----::~~::~ Image Surface -reflected path Figure5.15Low-angle tracking illustrating thesurface-reflected signalpathandthetargetimage.. I " , I .....L ,+--+----t-'--t-"""- I I.--1--__III1 !II, --+---'-I~I---+-+.-1---'.+ --i-'-.----+-- I I--'---Ji =....J... 
 MANCE  FROM BEING GENERATED .OISE !UTOMATIC 'AIN #ONTROL .!'#   4HE .!'# ATTENUATOR IS USED TO SET THE  THERMAL NOISE LEVEL IN THE RECEIVER TO SUPPORT THE REQUIRED DYNAMIC RANGE  AS DISCUSSED IN 3ECTION  4HE ATTENUATION IS COMMANDED BASED ON MEASUREMENTS OF THE NOISE DURING PERIODIC CALIBRATION $IGITAL 0REPROCESSING  4HE ADVENT OF HIGH 
 This is the province of space-time adaptive processing or  STAP.136 Here, the data used to determine the weights requires not just a single snap - shot or average of snapshots but a number of snapshots of the array outputs; this block  of data is then used to construct weights that are applied to the block of data before  beamforming and doppler analysis. STAP is of particular importance to ship detection,  where the external noise field almost invariably changes substantially during the long  CIT. The complexity of STAP in this context arises from the fact that each time the  weights are changed according to the SAP rules, the main beam experiences a phase  shift, even though its amplitude gain/sensitivity is preserved. 
 Subsequently, the radar data processor converted the digital recorded data into a two-dimensional map of the radar cross section of the area observed by the antenna. The SAR system generated a 25-m-resolution radar map in elevation (across track) by time-gated compressed radar return signals and in azimuth (along track) by focusing the coherent radar returns during the data-processing interval in the earth-based signal processor. Total SAR on-orbit weight was 223 kg; required radar prime power was 624 W. 
 The effect of atmospheric refraction on electromagnetic propa-  gation can be determined from a knowledge of the variation of index of refraction with altitude  over tlie path of propagation. From profiles of index of refraction, classical ray tracingz8 can  be applied to determine how the rays propagate. Generally, it is reasonable to assume that the  properties of the atmosphere vary only with height. 
 54. Gray, T.: Airborne Doppler Navigation Techniques, chap. 13 of" Radar Techniques for Detection,  Tracking, and Navigation." W. 
 Radar uses electromagnetic energy pulses in  much the same way, as shown in Figure 3. The radio -frequency (RF) energy is transmitted to and  reflected from the reflecting object. A small portion of the reflected energy returns to the radar set. 
 The paraboloid in Fig. 6.3a collimates radiation from a feed at the focus into a pencil beam, providing high gain and minimum beamwidth. The parabolic cylinder in Fig. 
 Pearson, E. Elshirbini, and M. S. 
 73. W. H. 
 L. J .. E. 
 Study of the results obtained in this type of analysis indicates that, in regions where the scattering coefficient does not change rapidly with angle, the widest possible angular width (obtained by a longer pulse or a wider filter for a CW- doppler system) results in the maximum number of independent samples for a given distance traveled along the ground. Near-Vertical Problem Most published radar return data purporting to include vertical incidence gives vertical-incidence scattering coefficients that are too small. This is a consequence of a fundamental problem in measuring near the vertical with a finite beamwidth or pulse length. 
 To minimize the loss in gain, each face would be tilted back an angle of 35.3" from  the vertical. Elements are arranged in an equilateral triangular pattern with element separa-  Table 8.3 Properties of hemispherical coverage arrays'23  Number of faces 3 4  Maximum scan angle 63.4" 54.7"  Tilt angle 26.6" . 35.3"  Element spacing (wavelengths) 0.628 0.69 1  Maximum power reflected 14% 7%  Maximum beam broadening 2.2 1.75  Maximum gain reduction (dB) 4.1 2.8  Relative total number of elements:  1. 
 SIBLE  THUS FORCING THE JAMMER INTO A BARRAGE 
 IEE (London) ,  pt. 4, vol. 101, pp. 
 The energy trapped by the duct suffers little loss; thus, targets may be detected at exceptionally long ranges. Surface targets have been detected atranges in excess of 1,400 miles with relatively low-powered equipment.There is a great loss in the energy of the rays escaping the duct, thusreducing the chances for detection of targets above the duct. Ducting sometimes reduces the effective radar range. 
 17. RADAR RELAY.... .. 
 PULSE JAMMING  IN WHICH THE %#- PULSE IS RETURNED TO THE RADAR WITH A HIGH *.2 SUCH THAT THE NORMAL TARGET RETURN IS COVERED BY THE JAMMING PULSE 4HE WIDTH OF THE %#- PULSE IS NORMALLY WIDER THAN THE RADAR SKIN RETURN  4HIS TYPE  OF DECEPTION CAN BE COUNTERACTED BY AN %##- TECHNIQUE SUCH AS THE COVER 
 TheButlernetwork utilizes(NI2)log2Njunc­ tions,justastheFFTuses(NI2)log2Ncomputations foranN-point transform. Within-pulse scanning.101-I04 Ifanantenna beamisscannedsequentially through itsangular coverage, oneposition atatime,itilluminates alldirections justasdoesamultiple-beam array.Ifthebeamisscanned rapidlyenough,however, itwillhavetheeffectofseeing..almost simultaneously" inalldirections. Thescanrateofthebeammustbegreaterthantheradar signal-bandwidth topreserve theinformation contained inthereceivedsignal.Theentirescan iscoveredwithinasinglepulse.Hence,thenamewithin-pulse scanning. 
 It is seen that 64,000 Ib can be delivered to a 100-nmi circular orbit inclined 50° from the Kennedy launch site in Florida. If each SBR weighs 9500 Ib, then three SBR satellites can be placed into orbit along with 35,500 Ib in propulsion for orbital transfer. Advantages and Disadvantages of SBR Systems. 
 Pedestals can a'ppear at the leading and trailing edges of the pulse, somewhat like the " rabbit  ears" found in traveling-wave tubes. They can be caused by the feedthrough of the RF  drive-pulse when it is wider than the d-c modulator pulse, or they can be due to spurious  oscillations, called band-edge oscillations, that occur just outside the normal tube-  bandwidth.16.'  The insertion loss of a CFA is low and might be less than 0.5 dB. The RF drive will thus  appear at the output of the tube with little attenuation. 
 STATE $ RADAR SYSTEMS SEE &IGURE   OPERATE AT , BAND BETWEEN n '(Z 4HESE SYSTEMS PROVIDE POSITION DATA FOR EN 
 The disadvantages ofthis method lieinthe excessive attenuation inthe trigger channel, the increased difficulty of delay-line construction, and the loss ofdesign flexibility due tothe necessity ofmixing thetrigger and thevideo signals atthetransmitting end ofthe delay line while preventing their interaction atthe receiving end. The third method oftrigger regeneration, already described inSec. 16.3, istheuseofanextra delay line inclose association with thesignal delay line asillustrated inFig. 
 MATORS FROM WHICH THE WEATHER PARAMETERS ARE DERIVED  0ROCESSOR )MPLEMENTATIONS  -ODERN METEOROLOGICAL RADARS USE DIGITAL SIGNAL  PROCESSING TECHNIQUES ON PROGRAMMABLE PLATFORMS AND INTERACTIVE COLOR DISPLAYS .   -%4%/2/,/')#!, 2!$!2   £°Óx FOR QUANTITATIVE PRECISION IN INTERPRETING THE WEATHER ECHOES -ODERN WEATHER RADARS  REQUIRE LARGE DYNAMIC RANGE TO SENSE STRONG ECHO AT SHORT RANGE AND WEAK ECHO AT LONG RANGE 4HUS  THE RECEIVER AND PROCESSOR DESIGNS ATTEMPT TO MAINTAIN AMPLITUDE AND PHASE LINEARITY THROUGHOUT THAT RANGE BY USING A DYNAMIC AUTOMATIC GAIN CONTROL !'#   WHEREBY THE RECEIVER GAIN AND PHASE ARE ADJUSTED ALONG THE RANGE INTERVAL THROUGH THE USE OF RAPIDLY SWITCHED ATTENUATORS OR  MORE OFTEN  DIGITAL COMPENSATION #LEARLY  SUCH RAPID SWITCHING IN THE RECEIVER REQUIRES CAREFUL DESIGN IN ORDER TO AVOID THE AFFECTS OF SWITCHING TRANSIENTS !N APPROACH THAT AVOIDS TRANSIENT EFFECTS IS TO USE TWO PARALLEL )& RECEIVER CHANNELS  EACH WITH MODERATE DYNAMIC RANGE AND FIXED GAINS  AND TO SAMPLE THE SIGNAL IN THE CHANNEL THAT IS BEST MATCHED TO THE SIGNAL STRENGTH )N ALL THOSE APPROACHES  IT IS POSSIBLE TO ACHIEVE LINEAR DYNAMIC RANGE OF GREATER THAN   D" AND TO USE FLOATING 
 The primary approach is to use an antenna with low sidelobes, par - ticularly in elevation, which will suppress the clutter component of the input echo  when the main beam is slightly above the horizon. A second approach is using shorter  wavelengths. Shorter wavelengths result in improved signal-to-clutter ratios owing  to the fact that the Rayleigh scattered weather signal power is inversely proportional  to l4, whereas the ground clutter return is only weakly dependent on wavelength. 
 1C.T.Button, “.4Carbon-pile Speed Governor, ”AlEE Transactions, 65, 4 (January 1946).. SEC. 14.7] DYNAMOTORS 579 14.7. 
 Ifourreceivers were very nearly ideal this would have the practical result ofmaking itmuch easier todetect aircraft appearing athigh angles ofelevation. Inthebest existing receivers the reduction innoise output which could beobtained bypointing theantenna upward would amount tosome 10per cent. The foregoing somewhat academic discussion ofthermal noise would beinappropriate inthis place were itnotfortwo facts. 
 The different responses to different polarizations of the electromagnetic wave  provide information on the target symmetry. It is this property that permits echoes from  symmetrical raindrops to be discriminated against in 'favor of echoes from asymmetrical  i~ircraft. Many microwave radars use circular polarization for this purpose. 
 This chapter sets out to explain the principal features of HF skywave radar as it is  presently implemented, emphasizing the physical considerations that govern system  design and performance. 20.2 THE RADAR EQUATION A form of the radar equation, Eq. 20.2, can be used to point to aspects of HF radar  that are significantly different from radars that use higher frequencies. 
 Res. Space Phys. 2010 ,115.[CrossRef ] 4. 
 Inoperation, either ahelical scan (Sec. 9.7) oracontinuous rotation in azimuth with manually controlled elevation can beused insearching for targets. The helical scan can besettocover any 12°inelevation angle intherange from 3°below to75°above thehorizon. 
 In general, errors of this nature have little impact on performance prediction. However, near-real-time analysis for virtual range and azimuth correction to great-circle distance and bearing (grid registration) requires that tilt or gradient effects be taken into account. The daytime example has little horizontal gradient, and the simplifying assumption makes little difference. 
 FIELD CALIBRATION INCLUDING MUTUAL COUPLING   NEAR 
 BY 
 10.2. The Resonant System.—In anoperating magnetron thecharge distribution intheresonant system produces electric fields which interact with thespace charge insuch away astosustain theoscillations. Figure 10.6cz illustrates such adisposition ofcharge and electric field atap instant when the concentration ofcharge onthe ends ofthe anode seg-. 
 WAY VERSUS TWO 
 ambiguities in the Doppler frequency develop if f d becomes > 1/T.   By higher PRF, as shown in Figure 8.1c, the opposite problem of unambiguity in the range to  target exists, since the period duration ∆t max = T = c 0/2Rmax is very small, while the Doppler  frequency is now unambiguous over a large velocity range.  In Figure 8.3 are represe nted the  spectra of the enlarged transmission and receiving signals. 
 The fluctuation ~nodels considered in this section assume either complete correlation  between pulses in any particular scan but with scan-to-scan independence (slow fluctuations),  . -, or else complete independence from pulse to pulse (fast fluctuation). These represent two  extreme cases. 
 PULSE CORRELATION IN SATELLITE RADAR ALTIMETRY v  2ADIO 3CIENCE  VOL     PP n    * 4 -C'OOGAN  , 3 -ILLER  ' 3 "ROWN  AND ' 3 (AYNE  h4HE 3 
 Improved estimators of Faraday rotation in spaceborne polarimetric SAR data. IEEE Geosci. Remote Sens. 
 T. Ransone, Jr., and J. C. 
 VATION MEASUREMENTS v  )%%% 4RANSACTIONS ON 'EOSCIENCE AND 2EMOTE 3ENSING  VOL      PP n    0 6INCENT  . 3TEUNOU  % #AUBET  , 0HALIPPOU  , 2EY  % 4HOUVENOT  AND * 6ERRON  h!LTI+A  A +A 
 14.29  14.14 Dual Modulat ion  ......................................................  14.30  14.15 Leakage  ..................................................................  14.30  14.16 Performance of FM-CW Systems  ........................... 
 Only when it is coherent is a degradation of clutter cancellation impossible. Consider a pseudo-coherent radar in which the interpulse periods are gener- ated from an independent source. Now the phase of the coho (a) changes from pulse to pulse, and although the phase of the desired echo from a stationary target changes equally, the phase of the spurious image echo changes oppositely. 
 77 CH1255-9, Arlington, V A, 1977, pp. 4-4A–4-40. 46. 
 can be set by observing the measurement error  x" -x,,". At the start of tracking the bandwidth is made wide and then it narrows down if the  target moves in a straight-line trajectory. As the target maneuvers or turns, the bandwidth is  widened to keep the tracking error small. 
 The major sources of target range-error  measurement errors are given in Table 9.3. Typical bias and noise of target range  measurement errors in a precision-ranging radar are equal to a total rms value of  1.6 m rms. Further details of range-error sources and their magnitude are give in  Section 10.3 of Barton.22 Limitations of Performance. 
 The Ectiles-Jordan Circuit. —Figures 13”13 to13”15 illustrate agroup oftwo-tube circuits inwhich thesharp transitions areproduced byposi- tive feedback from each plate tothealternate grid. Allarebased upon acircuit ofEccles and Jordan. 
 POL CAPABILITY IMPLIES A SIGNIFICANT COST 4HE DRIVING REQUIRE 
 Stuetzer, 0. M.: Development of Artificial Microwave Optics in Cierrnany, Proc. I RE, vol. 
 93 -96. IEEE Cat. no. 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.50  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 57. W. 
 Figure 9.4 plots noise figure as a function of frequency for  the several receiver front-ends used in radar applications. The parametric amplifier10• 18 has  the lowest noise figure of those devices described here, especially at the higher microwave  frequencies. However, it is generally more complex and expensive compared to the other  front-ends. 
 With circular polarization, however; there is no change with scan.  A conventional array with four faces can track four times the number of targets as a dome  antenna (which operates with a single planar array for hemispherical coverage), assuming the  traffic is distributed uniformly. The average power required for the planar array of the dome  antenna is approximately the sum of the average powers required for each of the individual  arrays, assuming comparable performance. 
 The gyro may bemounted onthe rotating scanner or remote from the scanner, using slip rings and resolvers totake offthe required error information. The error isfedinto aservoamplifier whose output operates the servomotor which inturn aligns the antenna with thehorizontal through agear train orlinkage system. The gyro should preferably have either atwo-speed erection mecha- nism oradevice todisconnect theerection mechanism when theaircraft goes into aturn. 
 When  observed over a sufficient number of samples, the noise pulses will occupy all parts  of the range swath in one sample or another. The azimuth processor forms the sum  of the noise power from all samples within one synthetic aperture length. That sum  will be equal to the total noise power in the aperture, which is proportional to the  average jammer noise power. 
 Chow, P. E. K., and D. 
 Thus, ade- quate stabilization ofthebeacon transmitter isrequired, and thereceiver forthe signals must have automatic frequency control, orawavemeter must beprovided, oritmust bepossible tosetthefrequency accurately topreset values byhaving mechanical parts ofsufficient precision. All ofthese techniques have been worked out and arenow available. This useofaspot frequency forthe reply does have adisadvantage, however. 
 24.3  24.3 Transmitters  ............................................................  24.4  24.4 Antennas  ................................................................  24.5  24.5 Clutter: The Echo from the Earth  ............................ 
 Power-aperture product as a measure of radar performance is fundamental. It is so fundamental that it was explicitly mentioned in the SALT-I Treaty as the basis for limiting the capabilities of antiballistic missile (ABM) radars. Receiver sensitivity is not shown as a factor in Eq. 
 Thelocaloscillator signalsofFig.8.29arederivedcoherently bymixingthetwofrequen­ ciesIIand.l~andfiIteringthedesiredmixerproductsI,+nis'n=I,2,...,N.ThefrequencyIS! whichistherateatwhichthefarfieldissampled, mustbegreaterthanthetotalsignal bandwidth ifthemodu.lation envelope oftheradarpulsesistobepreserved. Theoutputsfrom theelements mustbelimitedtoabandwidth Bbeforeaddingthemalltogether, ifnoiseoverlap istobeavoided. Therequired bandwidth ofthesummed signalchannel isNf"whichmustbe madegreaterthanNB.Thiscanbequitelarge(perhaps severalgigahertz insomeradars)and canrepresent alimitation ontheimplementation ofthetechnique. 
 E.: Variable-elevation-beam Aerial Systems for 11 Metres, J. I EE, vol. 93, pt. 
 The characteristics of this  filter need to adapt to the quality of the received target signal. If tracking is carried  out in ground referenced coordinates, the process automatically takes into account  own-ship movements. In relative motion-based tracking systems, the filter needs to be  aided with own-ship data. 
 The latter usehas, and will probably continue tohave, aconsiderable peacetime importance. Lobe-sw”tching andPip-matching-The first radar setintended for precision tracking ofasingle target was theSCR-268, alaboratory proto- type ofwhich was formally demonstrated tothe Secretary ofWar in May 1937. The problem ofaccurately tracking amoving target with an antenna that can beelevated and trained issimilar tothe problem of homing with the help of.fixed antennas onamovable vehicle, and the same techniques areuseful. 
 The dielectric materials must not be too heavy, yet they must be strong enough to support  tlterr own weight without collapsing. They should have low dielectric loss and not be affected  by the weattier or by changes in temperature. They should be easily manufactured wit11  ilriiform properties and must be liomogeneous and isotropic if the performance characteristics  are to be iridepeildcrit of positio~i. 
 These waveforms are accu - mulated and averaged pulse-to-pulse, whose shape converges on the flat-surface  impulse response65,66 (Figure 18.8). Sea-surface height (SSH) is derived from the  time delay to the midpoint of the waveform’s leading edge rise. One thousand or  more such waveforms averaged over one second correspond to a mean range esti - mate whose standard deviation is on the order of centimeters (which, in practice,  degrades with increasing significant wave height). 
 These ship chips are split into training, validation dataset, with percentages of 70% and 30%, respectively. 3.2. Hyperparameters In this paper, the momentum we set is 0.9. 
 46 Selection of polarization signatures from SAR image of  San Francisco: ( a) an ocean area, ( b) a large park, and ( c) one of several  urban areas ( after D. L. Evans32 © IEEE 1988 ) CO-POLARIZED CROSS-POLARIZED Circular Linear OCEAN+45°0° −45°180°90°0°01 PARKPedestal (unpolarized) URBAN 1(c)(b)(a) Horizontal Vertical χtψtRelative Power ch16.indd   51 12/19/07   4:56:45 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 E. Hoffmann-Heiden, “Anti-jamming techniques at the German AAA radars in World War II,”  suppl. to IEEE Int. 
 CUIT ELEMENTS ARE FORMED ON A SEMI 
 L. Rice, “Predictions of troposphere radio transmission loss over irregular  terrain: A computer method,” Environmental Science Services Administration Tech. Rep. 
 " RADAR DESIGN STUDIES v  TH  !'!2$ 3YMPOSIUM ON @5SE OR 2EDUCTION OF 0ROPAGATION AND .OISE %FFECTS IN $ISTRIBUTED  -ILITARY 3YSTEMS  !'!2$ #0 
 Extremely precise indices can begenerated inthis way, although the error ofmost phase-shifting elements islarge (0.3 per cent). Space permits nodescription ofthis method but thereader isreferred toChap. 4ofVol. 
 QUENCY IS PLOTTED AS A FUNCTION OF TIME AT THREE POINTS IN THE STRETCH PULSE COMPRESSION SYSTEM BLOCK DIAGRAM   CORRELATION MIXER INPUT    CORRELATION MIXER ,/ REFERENCE WAVEFORM GENERATOR OUTPUT   AND   CORRELATION MIXER OUTPUT OUTPUT OF BANDPASS FILTER  4HREE ,&- TARGET SIGNALS ARE SHOWN AT THE CORRELATION MIXER INPUT TARGET  IS AT ZERO TIME OFFSET RELATIVE TO THE REFERENCE WAVEFORM TARGET  IS EARLIER IN TIME THAN THE REFERENCE WAVEFORM AND TARGET  IS LATER IN TIME )N EACH CASE  THE ,&- SLOPE FOR THE TARGET SIGNALS IS  "4 4HE REFERENCE WAVEFORM APPLIED TO THE ,/ PORT OF THE #- HAS  ,&- SLOPE EQUAL TO " 242   "4  4HE INSTANTANEOUS FREQUENCY AT THE CORRELATION MIXER OUTPUT IS THE DIFFERENCE  BETWEEN THE INSTANTANEOUS FREQUENCIES AT THE #- INPUT AND ,/ PORTS !S A RESULT  THE #- OUTPUT SIGNALS FOR THE THREE TARGET SIGNALS ARE UNCODED PULSES PULSED #7 SIGNALS  WITH FREQUENCY OFFSET FROM THE MIXER )& OUTPUT F )& GIVEN BY    DF" 4TD 
 Synthetic aperture radar target recognition with feature fusion based on a stacked autoencoder. Sensors 2017 ,17, 192. [ CrossRef ][PubMed ] 5. 
 Moreover, the EMAM method can further estimate ˆe3rd1well. (a)  Amplitude (dB)   (b)  Amplitude (dB)   (c)  (d)  Figure 10. The azimuth impulse responses of targets by the different methods with the velocity and acceleration errors. 
 Thesespeedsareusuallytoohightobecompletely rejected bymostmicrowave MTIradars. Mostbirdsflyataltitudes belowabout2500m,withpeaknumbers between 300and1200m, orevenlower.95•96 Table13.3givessomeexamples oftheradarcrosssections ofbirdstakenatthreefrequen­ cieswithverticalpolarization.91ThelargestvaluesoccuratSband.Otherexamples ofcross sectionaregiveninFig.13.14,whichplotstheaverageradarcrosssectionasafunction ofthe weightofthebird.Thesolidcirclesaretheaverages overa±200sectoraroundthebroadside aspect.92Thex'saretheaverage ofthe±200head-on and±200tail-onaspects.92.93(Note thatthevaluesgivenforthepigeoninFig.13.10differfromthosegiveninTable13.3.Thetwo setsofvaluesarefromdifferent sources.) Theradarcrosssectionofbirdsdoesnotshowasimplewavelength orsizedependence. 91 Thereareresonant effects,asillustrated bythemeasured crosssectionofa2!-lbduckatUHF beingnearlytwicethatofa41-lbduck.94(Themedianvalueofthe41-lbduckhead-on was 600cm2,and24cm2tail-on.) Thebackscatter frombirdsfluctuates overquitelargevalues withthemaximum andminimum differing attimesbymorethantwoordersofmagnitude.91 Thusitisdifficulttodescribe theradarcrosssectionbyasinglevalue.Itshouldproperly be. 
 Wilson. and J. J. 
 TION IN FREE 
 D" AND  
 PULSE CHANNEL  WHERE THE TRACKING IS ON THE %#- TRANSMISSION RATHER THAN ON THE SKIN RETURN FROM THE TARGET  4HE DIGITAL COHERENT IMPLEMENTATION OF THE $ICKE 
 (ILL "OOK #OMPANY     9 4 ,O  h/N THE "EAM $EVIATION &ACTOR OF A 0ARABOLIC 2EFLECTOR v  )2% 4RANS  VOL !0 
  
 M TOWER WITH  TWO EQUIPMENT SHELTERSONE CONTAINING THE TRANS 
 E 4  0.4 ( 1)  Frequency  Figure 4.12 Amplitude responses for three MTI delay-line cancelers. (1) Classical three-pulse canceler,  (2) five-pulse delay-line canceler with "optimum" weights, and (3) 15-pulse Chebyshev design. ( Afcer fl outs  and Burlage.26)  W; = weight at the ith tap.) A large number of delay lines are seen to be required of a  nonrecursive canceler if highly-shaped filter responses are desired. 
 where Pr = received signal power, W  P, transmitted power, W  G = antenna gain  J.. = wavelength. m  a111 monostatic cross section (backscatter). 
   DOPPLER hHYPERBOLASv BECAUSE THE %ARTH IS A ROUGH GEOID  CONSTANT RANGE AND DOPPLER CONTOURS ARE NOT ACTUALLY RINGS OR HYPERBOLAS  4HE RADAR ANTENNA PATTERN INTERCEPTS THE LIMB OF THE %ARTH USUALLY IN BOTH THE MAIN BEAM AND SIDELOBES ! TARGET IN THE MAIN BEAM AT RANGE   2 T  AND VELOCITY   6T  MAY HAVE TO BE OBSERVED IN THE PRESENCE OF BOTH  RANGE AND DOPPLER AMBIGUITIES /NLY THE TARGETS LINE 
 560INTRODUCTION TORADAR SYSTEMS Although thebistatic radarhasmanyinteresting attributes, itcannotcompete with monostatic radarinmostradarsystemapplications. Thehistoryofradarsubstantiates this conclusion. Themonostatic radaristhemoreversatile ofthetwobecauseofitsabilitytoscan alargevolume inspaceandbecause oftherelative easewithwhichusableinformation concerning thetarget'sposition andrelativevelocitycanbeextracted fromthereceived signal. 
 97.Foster,H.E.,andR.E.Hiatt:ButlerNetwork Extension toAnyNumber ofAntenna Ports,IEEE Trans.,vol.AP-18,pp.818-820, November, 1970. 98.Cheston, T.C,andJ.Frank:ArrayAntennas, chap.IIof"RadarHandbook," M.I.Skolnik (ed.), McGraw-Hill BookCo.,NewYork,1970,sec.11.9. 99.Sheleg,B.:ButlerSubmatrix FeedSystems forAntenna Arrays,IEEETrans.,vol.AP-21,pp.228-9, March, 1973. 
 TO 
 After interpolation, the original coordinate axis kris replaced by the new coordinate axis ky. Figure 7is the bandwidth of the spectrum after interpolation, and the effective spectrum is the part within the dashed box. Figure 5 shows the spectrum of the traditional interpolation method, and the spectrum is approximated as a character quadrilateral. 
 TIME ADAPTIVE PROCESSING OR 34!0  (ERE  THE DATA USED TO DETERMINE THE WEIGHTS REQUIRES NOT JUST A SINGLE SNAP 
 57. M. B. 
 (9.15) the overall noise figure of a radar receiver with a noise figure F, preceded  by RF circuitry with a loss l..ttF, is equal to F, l..ttF. In a radar the overall loss l..ttF due to the . RECEIVERS, lJISPLAYS, AND DUPLEXERS 353  transmission line, rotary joint, duplexer, receiver protector, and preselector filter might not be  insignificant. 
 38. Riblet, H.J.: The Short-Slot Hybrid Junction, Proc, IRE, vol. 40, pp. 
 S. Nozette, C. L. 
 The utiambiguous regions must be  s~nallcr tlian ;~ssr~nicd in the above to allow for tlie fact tliat antenna patterns are riot zero  outside tlie niapped re.gio~i.~.'"or a uniform aperture illumination of the real antenna.  Eq. (1 4.9) becomes4  Essentially tile sariie rcsirlt is obtained for a cosine-weight aperture illumination. 
 When a transmitter is producing FM noise, it may be thought to be modulating in frequency at various rates and small deviations. Consider, for example, a partic- ular one of these modulating frequencies. If it is a low frequency and the delay associated with the spillover or clutter is short, the returning signal finds the car- rier at nearly the same frequency that it had at the time of transmission; that is, the decorrelation is small. 
 This is a  relatively low value for a practical pulse-compression waveform. When a larger pulse­ compression ratio is desired, some form of pseudorandom code is usually used. A popular  technique is the generation of a linear recursive sequence using a shift register with feedback,  as in Fig. 
 Synthetic Aperture Radar (SAR) T echniques and Applications Special Issue Editor Fabio Bovenga MDPI•Basel•Beijing•Wuhan•Barcelona •Belgrade •Manchester •Tokyo•Cluj•Tianjin . Special Issue Editor Fabio BovengaItalian National Research Council,Institute for ElectromagneticSensing of the Environment(IREA)Italy Editorial Ofﬁce MDPI St. Alban-Anlage 66 4052 Basel, Switzerland This is a reprint of articles from the Special Issue published online in the open access journal Sensors (ISSN 1424-8220) (available at: https://www.mdpi.com/journal/sensors/special issues/ SAR techniques applications). 
 Holm, Yesdee,2013.   4. ‘Radar Hand Book ‘ Ed. 
 2003 ,39, 769–776. [ CrossRef ] 22. Ponce, O.; Prats, P .; Rodriguez-Cassola, M.; Scheiber, R.; Reigber, A. 
 DOTTED LINES  30-  "RAGG DASHED LINE  TWO 
 These loss factors are multiplicative; . that is, if there are, for example, three loss factors L1, L2, and L3, they can be represented by a single system loss factor L = L7L2L3. The resulting maximum- range equation is . 
 14).  The distance d to the horizon from a radar at height /I may be shown from simple  geometrical cotlsideratiorls to be approximately  where ka is the effective radius of the earth and h is assumed small compared with a. For k = 8,  Eq. 
 1962.  138. Zhuk. 
 .!3! 3YMPOSIUM ON 3HORT 4ERM &REQUENCY 3TABILITY   .!3! 
 STORY 
 Appl. Remote Sens. 2018 , 12, 026001. 
 The target is a Super Constellation aircraft in night. Note that the angle video indicates to what side  or the radar beam axis are located the individual scatterers which are resolved in range. The radar  operated at X hand with a 7-ft-diameter antenna and a pulse width of 3 nanoseconds.66 . 
 In such cases the AGC can still perform satisfactorily since the loop gain is usually low  for small signals. Thus the AGC will not regulate weak signals. The effect is similar to having a  delay voltage, but the performance will not be as good. 
 No. 105. Radar. 
 A different system design philosophy usually must be  employed with solid state.  To increase the power output, transistors may be operated in parallel. From 2 to 8 devices  arc usually combined into a single power module. 
 TARGET TRACKER USED  FOR DEFENDING AGAINST AIR ATTACK 'UIDANCE RADAR 4HIS IS USUALLY A RADAR ON A MISSILE THAT ALLOWS THE MISSILE TO  hHOME IN v OR GUIDE ITSELF  TO A TARGET7EATHER METEOROLOGICAL  OBSERVATION  3UCH RADARS DETECT  RECOGNIZE  AND MEASURE  PRECIPITATION RATE  WIND SPEED AND DIRECTION  AND OBSERVE OTHER WEATHER EFFECTS    #OHERENT IMPLIES THAT THE PHASE OF THE RADAR SIGNAL IS USED AS AN IMPORTANT PART OF THE RADAR PROCESS.   !. ).42/$5#4)/. !.$ /6%26)%7 /& 2!$!2   £°Ç IMPORTANT FOR METEOROLOGICAL PURPOSES 4HESE MAY BE SPECIAL RADARS OR ANOTHER  FUNCTION OF SURVEILLANCE RADARS $OPPLER WEATHER RADAR 4HIS IS A WEATHER OBSERVATION RADAR THAT EMPLOYS THE DOP 
 It was assumed in the analysis of a bandwidth-limited  pulse that a matched filter was employed. H the spectral width of the .. rectangular" pulse is  changed, the matched filter must be changed also. 
 15, pp. 185–200, 1984. 151. 
 Images with traditional ways. ( a–c) Bulk Carrier images with processing. ( d,e) Container Ship images with processing. 
 ARRAY ANTENNA 4HE AMPLITUDE AND PHASE OF THE SIGNALS DELIVERED BY THE  . AUXILIARIES ARE CONTROLLED  BY A SET OF SUITABLE WEIGHTS DENOTE THE SET WITH THE  . 
 M. I. Skolnik, Introduction to Radar Systems,  Chapter 3, 3rd Ed. 
 Trends.  Vector wind data have been adopted by operational meteorological  agencies such as EUMETSAT. It is likely that space-based microwave assets will  continue to be used for the foreseeable future to provide these data. 
 It was shown in Sec. 3.1  that the c.loppler frequency shift was proportional to.the carrier (rf) frequency. This results in  more accurate relative-velocity measurements with millimeter wavelengths than at lower  frequencies. 
   
 The mixers  must have DC coupled IF output ports and be presented with a good match at both the  wanted low frequency output and the unwanted sum frequency. A match at the sum  frequency can be provided using a diplexer filter. Video filtering is required to reject  the sum frequency mixer outputs and also provides rejection of wideband noise from  the video amplifiers, which would otherwise alias to baseband through the A/D con - verter sampling process, producing an unwanted degradation of receiver noise figure. 
 Wilkins, who had featured in the Daventry  experiment, went on to develop IFF, while another  young member of the National Physical Laboratory,  E. G. Bowen, started pioneer work in airborne radar. 
 4.6. A portion  of the transmitted signal is mixed with the stalo oµtput to produce an IF beat signal whose  phase is directly related to the phase of the transmitter. This IF pulse is applied to the coho  and causes the phase of the coho CW oscillation to "lock" in step with the phase of the IF  reference pulse. 
 Leakage inductance “can bekept toareasonable value bywinding the secondary and primary asclose together asvoltage breakdom will permit, forthe space between these two windings isresponsible formost oftheleakage inductance. The shunt inductance and itsmagnetizing current con- stitute anadditional load onthe generator which must beminimized by making L.large. This last consideration sets alower limit onthe number ofprimary turns and also calls foralaminated core with high permeability athigh frequencies. 
 On transmit, power emanat - ing spherically from a low gain, broad-patterned feed is reflected and energy is col - limated to form a plane wave thereby providing increased antenna gain and a narrower  beamwidth. In discussing antennas, one can use either transmit or receive arguments  because antennas are reciprocal devices. This means that both the transmit and receive  performance of a passive antenna, e.g., patterns, gain, losses, etc., can be predicted  using basic aperture antenna principles. 
 While the compressed output obtained with the recipr ocal ripple  filtering, shown in Figure 12.26, would provide extremely low side lobe, t his performance  would be unachievable in practice, because the required filtering implies an infinite impulse response. The duration of this impulse response must be taken into a ccount regardless of  whether pulse compression is performed with a finite leng th FIR filter, or whether it is based  on the FFT approach. Furthermore, as mentioned above, the use of a phase -only matched filter  will also result in an extended duration impulse response. 
 The  multipath errors that result are cyclic, almost sinusoidal, with an rms value pre - dicted by the equation46  σρθ EB G= 8sepeak) ( (9.8) where sE = rms elevation angle multipath error, same units as qB  qB = one-way antenna beamwidth  r = reflection coefficient and Gse (peak) is the power ratio of the tracking-antenna sum-pattern peak to the error- pattern peak sidelobe level at the angle of arrival of the image signal. The cyclic rate may be approximated by the equation  fhE m=2 λ (9.9) where fm = frequency of cyclic multipath error, rad/s  h = height of radar antenna  l = wavelength, same units as h  E = rate of target elevation change as seen by radar, rad/s The intermediate range is between the short-range region where the image  appears in the sidelobes, and the long-range region, where the image appears within  the half-power beamwidth. The error is difficult to calculate in this region because  it falls in the nonlinear error-sensing portion of the antenna patterns, and the radar  response is strongly dependent upon the specific feed design and error-processing  technique. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°Óx CONVENTIONAL INTERFEROMETRIC 3!2 MEASUREMENTS FROM ONE SPACECRAFT PLATFORM USUALLY  ARE NOT PRACTICAL  SINCE THE IMPLIED SPATIAL OR TEMPORAL SEPARATIONS OF THE MEASUREMENTS ARE MUCH LARGER THAN ONE SATELLITE COULD SUPPORT !N ALERT READER MAY NOTE THE OBVIOUS EXCEPTION TO THIS RULE  324- DESCRIBED PREVIOUSLY  WHICH MOUNTED ITS SECOND INTER 
 J.Electroll., (London). vo!.1,pp.389-404, 1956. 54.Betts.F..D.H.Temme.andJ.A.Weiss:ASwitchable Circulator: S-band;Stripline; Remanent; 15 Kilowatts; 10Microseconds; Temperature Stable,IEEETrans.•vol.MTT-14, pp.665-669, Decem­ her.1966. 
 only bythesmall drop acrossR~.IfSissuddenly opened, thecurrent is“shifted from StoC,and thelatter starts tocharge exponentially ata rate determined byR,C,and E. The rising wave ofthesawtooth isan exponential oftime constant RC,asindicated inWaveform 2ofFig. 1329. 
    
  $$# !$ 
 J.: Satellite-Borne Radar, Lecture IX, Adv. Radar Technol. Short Course, scheduled by Technology Service Corporation, San Diego, Apr. 
 DEVICE APPLICATIONS v  -ICROWAVE *  VOL   PP n   *ANUARY . n°{Ó  2!$!2 (!.$"//+    * 7  !RTHUR  h-ODERN 3!7 
 TO 
 The diffraction difficulty can largely beovercome bythecareful useofdiversity antennas. 17.11. General Transmitter and Receiver Considerations.-Although the specific characteristics desirable inthe transmitter and receiver depend upon theparticular application, certain general statements canbe made. 
 SIDELOBE PERFORMANCE !N ELECTRONICALLY PROGRAMMABLE GAIN ADJUSTMENT MAY BE HELP 
 Palmour, and C. Carter, “Silicon carbide MESFETs for high  power S-band applications,” in IEEE MTT-S International Microwave Symposium , June 1997,  pp. 57–60. 
 FIELD ANTENNA MEASUREMENT FACILITY   !N ATTRACTIVE FEATURE OF THE NEAR 
 Rotating the para-  bolic curve shown in Fig. 7.6 about its axis produces a parabola of revolution called a circular  parabola, or a paraboloid. When properly illuminated by a point source at the focus, the  paraboloid generates a nearly symmetrical pencil-beam antenna pattern. 
 Crispin, J. W., Jr., and K. M. 
 I. M. Hunter. 
 Separate thresholds are applied  to each filter. The thresholds for the nonzero-velocity resolution cells are established by  summing the detected outputs of the signals in the same velocity filter in 16 range cells, eight  on either side of the cell of interest. Thus, each filter output is averaged over cne mile in range  to establish the statistical mean level of nonzero-velocity clutter (such as rain) or noise. 
 Radar-Present and Ftrture, IEE Conf. Publ. no. 
 Ifthe target isat zero elevation, theslant beam will illuminate it10°later, atA‘. If the target has adefinite height, theslant beam will rotate further before illuminating itand the signal will actually appear atB,as shown. Amovable overlay superimposed onthescope face issetsothat itsbaseline bisects thefirst signal atA The 10°delay position ismarked byasecond line, which serves asthe zero-height line forasuccession of constant-height lines which appear asdrawn. 
 Abeacon can afford positive identifi- cation oftheaircraft carrying it. Freedom from ground clutter. Byhaving the beacon reply ata frequency different from that used bytheradar forinterrogation, the beacon replies can bedisplayed without any confusing radar echoes. 
 fault location, data recording and simulations; and the exerntive ma11ageme11t of the radar  by assigning priorities to the various tasks and how they should be performed so as to achieve  a compromise between the required radar actions and the resources available in the radar  and computer. In addition, the computer provides the means whereby an operator can manually  interact with the radar.  Beam-steering computer. 
 It is not necessary, however, to employ such an  clahoratc set of data sirice for most engineering purposes the curves of Figs. 2.23 and 2.24 may  be used as corrections to the probability ofdetection (as found in Fig. 2.7) and as the integration  irni>rovcmcnt factor (Fig. 
 51–83, January 1978. 69. T. 
 RADIUS   A  ARE RELATED  BY AN EFFECTIVE 
 '· . Efficiency of nonmatched 61ters. In practice the matched filter cannot always be obtained  exactly. 
 The result is very similar: power and aperture are still the driving . factors, and a balanced system design again results in significant transmitter power. The inescapable conclusion is that "It's watts up front that count." The desire to attain maximum radar performance capability thus means, more often than not, that both the antenna size and the transmitter power are pushed to the max- imum affordable. 
 +1 
 SCATTERING CHARACTERISTICS OF LAND AND SEA AT 8 BAND v IN  0ROC .ATL #ONF  !ERONAUT %LECTRON    & # -AC$ONALD  h4HE CORRELATION OF RADAR SEA CLUTTER ON VERTICAL AND HORIZONTAL POLARIZATION WITH  WAVE HEIGHT AND SLOPE v IN )2% #ONV 2EC  VOL     PP n  7 3 !MENT  & # -AC$ONALD  AND 2 3HEWBRIDGE  h2ADAR TERRAIN REFLECTIONS FOR SEVERAL POLAR 
 This tube is suitable for air-search radar. Similar TWTs have been used in  phased-array radar. The Air Force Cobra Dane phased-array radar, for examplc, irscs 96  Gun  Cothode, ,{anode  Electron '  beam Attenuation Collector -',  RF . 
 Gary, and G. W. Ewell: Radar Sea Clutter at 9.5. 
 The effects of A/D and D/A converter clock phase noise and jitter is described in  Sections 6.10 and 6.13. The jitter on timing strobes used to perform transmit/receive  (T/R) switching is typically less stringent than that of A/D clocks, as it does not have  a direct impact on the signal phase. However, if components such as transmit/receive  switches or power amplifiers have a transient phase response of significant duration,  time jitter on the switching time can be translated into a phase modulation of the  transmitter or receiver signal. 
 A second simulation, involving only two targets, investigated the  effect of target suppression on log video, and the results are summarized in Table 7.2.  The maximum value of PD2 is obtained when both targets have an S/N of 20 dB. If one  of the targets has a larger S/N than the other target, suppression occurs—either target 1  suppresses target 2 or vice versa. 
   .OVEMBER   ( - &INN AND 2 3 *OHNSON  h!DAPTIVE DETECTION MODE WITH THRESHOLD CONTROL AS A FUNCTION OF  SPACIALLY SAMPLED CLUTTER 
 WINDOW INTEGRATOR BECAUSE OF THE HARD LIMITING OF THE DATA  AND THE ANGULAR ESTIMATION ERROR IS ABOUT  PERCENT GREATER THAN THE #RAMER 
 A. Sloane: Pseudo-Random Sequences and Arrays, Proc. IEEE, vol. 
  AND PHASE 
 CAVITY KLYSTRON )T HAS BEEN SAID FOR A GIVEN &)'52%    "ASIC STRUCTURE OF SEVERAL TYPES OF LINEAR  BEAM TUBES  A  KLYSTRON   B  COUPLED 
 This block diagram is representative of a  modern air traffic control radar operating at L or S band with a typical interpulse period  of 1–3 ms and a CW pulse length of a few µs when the transmitter employs a vacuum  tube amplifier such as, for example, a klystron, or tens of µs for a pulse compression  waveform when a solid-state transmitter is used. The received signals are amplified in  a low-noise amplifier (LNA) and subsequently downconverted through one or more  intermediate frequencies (IF) by mixing with stable local oscillators. A bandpass IF  limiter at the receiver output protects the A/D converter from damage but also prevents  limiting from taking place in the A/D converter. 
 24.5. A number of natural scatterers have been described at the 1981 Symposium on the Effect of the Ionosphere on Radiowave Systems.31 Findings on the nature of auroral echoes are given by Greenwald,8 and an auroral echo-scattering model has been developed by Elkins.32 Chapter 4 of Ref. 7 treats the RCS associated with rockets and their exhausts. 
 If the radar has sufficient resolution capability in range or angle,  it can provide a measurement of the target extent in the dimension of high resolu - tion. Range is usually the coordinate where resolution is obtained. Resolution in cross  range (given by the range multiplied by the antenna beamwidth) can be obtained with  very narrow beamwidth antennas. 
  
 Continuous rainfall over a large area will make the center part of the screen brighter than the rest and the rain clutter, moving along with the ship,looks similar to sea clutter. It can be clearly seen on long range scales. Thisisduetoagradualdecreaseinreturningpowerasthepulsepenetratesfurtherinto the rain area. 
 RESOLUTION DIGITAL CLUTTER MAP TO SUPPRESS CLUTTER RESIDUES IS RELATED TO EARLIER EFFORTS TO CONSTRUCT ANALOG AREA -4) SYSTEMS USING  FOR EXAMPLE  STORAGE TUBES !LSO INCLUDED IN THE -4$ IMPLEMENTATION ARE hxAREA THRESHOLDS MAINTAINED  TO CONTROL EXCESSIVE FALSE ALARMS  PARTICULARLY FROM BIRD FLOCKS %ACH AREA OF ABOUT  SQUARE NAUTICAL MILES IS DIVIDED INTO SEVERAL VELOCITY REGIONS 4HE THRESHOLD IN EACH REGION IS ADJUSTED ON EACH SCAN TO ACHIEVE THE DESIRED LIMIT ON FALSE ALARMS WITHOUT RAISING THE THRESHOLD SO HIGH THAT SMALL AIRCRAFT ARE PREVENTED FROM BEING PLACED IN TRACK STATUSv  )N SUBSEQUENT SECTIONS  SPECIFIC ASPECTS OF THE DESIGN OF AN -4$ SYSTEM WILL BE  DISCUSSED 4HUS  3ECTION  WILL DISCUSS THE DESIGN AND PERFORMANCE OF DOPPLER FILTER BANKS  AND A DETAILED DISCUSSION OF CLUTTER MAPS WILL FOLLOW IN 3ECTION  3INCE THE ORIGINAL WORK AT ,INCOLN ,ABORATORY TO DEVELOP THE -4$ CONCEPT  A NUMBER OF -4$ SYSTEMS HAVE BEEN DEVELOPED THAT VARY IN DETAIL FROM THE ORIGINAL CONCEPT !LSO  THE USE OF CLUTTER MAPS TO INHIBIT EXCESSIVE CLUTTER RESIDUE  INSTEAD OF CONTROL 
 The operation ofthemethod illustrated isdescribed below. The comparison pulse triggers aflip-flop. The square waves from the two plates, one positive and one negative, arefedtothecontrol grids ofapair ofpentodes (Fig. 
 Kdp is the suitably smoothed range  derivative of the measured differential phase, Φdp, and is usually expressed in deg/km.  rhv is the co-polar correlation coefficient of Eh and Ev where the phase measurements  are assumed to be time coincident, which is the case with SHV transmission and recep - tion. LDR is a ratio of the cross-polar vertical reflectivity ( Zcx v) normalized by the  co-polar horizontal reflectivity ( Zco h). 
 A simple block diagram of a radar siiperheter-  odyne receiver was shown in Fig. 1.2. There are many factors that enter into the tlesign of  radar receivers; however, only the receiver noise-figure and the receiver front-end, as they  determine receiver sensitivity, will be discussed here. 
 RANGE  INTERVAL DISPLAY RANGERANGE GATE SIZE . {°{È  2!$!2 (!.$"//+  &OR BETTER FALSE ALARM REJECTION  DOPPLER CORRELATION CAN BE US ED FOR -273 )N THE  CASE WHERE BOTH RANGE AND DOPPLER CORRELATION ARE USED  THE REQUIRED 0&! IS   04 M N..47D M&! FU RU &2 ¤ ¦¥³ µ´§ ©¨ ¨¨¨¶ ¸· ·· 
 The resemblance between arectangular waveguide and atwo-wire transmission line isshown inFig. 11.8a to11.Sd.InFig. 11.8a isshown asingle quarter-wave stub support, analogous tothecoaxial stub support described inSec. 
 Inparallel with itisthe capacity Coftheboundary layer ofthe 1Crystal Rectifiers, Vol. 15.lbdiationLaboratory Series.. SEC. 
 66INTRODUCTION TORADAR SYSTEMS 26.Peters,L.,Jr.:End-fire EchoAreaofLong,ThinBodies,IRETrails.,vol.AP-6,pp.133-139, January, 1958. 27.Blore,W.E.:TheRadarCrossSectionofOgives, DoublecBacked Cones,Doubk-Rounded Cones andConeSpheres, IEEETrans.,vol.AP-12,pp.582-589, September, 1964. 28.Ridenour, L.N.:'~Radar SystemEngineering," MITRadiation Laboratory Series,vol.I,fig.3.8, McGraw-Hill BookCompany, NewYork,1947. 
 A. Farina, “Digital equalisation in adaptive spatial filtering: a survey,” Signal Processing , Elsevier,  vol. 83, no. 
 They are ever-pres - ent and constitute a major source of clutter for HF radars.19 • Large and medium scale atmospheric gravity waves (AGW) produced by energetic  phenomena in the lower atmosphere propagate upward with increasing amplitude  until nonlinear processes begin to dominate, resulting in wave breaking. Large AGWs  may persist for hours and propagate over global distances, causing serious deviation  of incident radiowaves.23 They are sometimes the major cause of tracking errors. • Magnetic disturbances originating where the solar wind impacts on the magneto - sphere; they propagate earthward and cause resonant oscillations of the geomagnetic  field lines permeating the ionosphere. 
 320 10.l Construction ...... .321 10.2 The Resonant System ..... .325 10.3 Electron Orbits andtheSpace Charge 330 10.4 Performance Charts andRieke Diagrams 336 10.5 Magnetron Characteristics Affecting Over-all Systems Design 340 10.6 Magnetron Characteristics Affecting Pulser Design 352 TEE Puller .......... 
 and K. W. lklrnke: Real-Time Tracking Filter Evaluation and Selection for Tactical  Applications. 
    OR    
 LOADING 4HE DIELECTRIC CONSTANT OF THE  BLOCK CAN BE QUITE LOW   WHICH  WITH THE REDUCED WIND 
 ING COHERENT INTEGRATOR 6)#)   AND THE COHERENT MEMORY FILTER #-&   !LTHOUGH THESE IMPROVEMENTS HAVE ENABLED MUCH IMPROVED -4) CAPABILITIES   THERE ARE STILL NO PERFECT SOLUTIONS TO ALL -4) RADAR PROBLEMS  AND THE DESIGN OF AN -4) SYSTEM IS STILL AS MUCH OF AN ART AS IT IS A SCIENCE %XAMPLES OF CURRENT PROBLEMS INCLUDE THE FACT THAT WHEN RECEIVERS ARE BUILT WITH INCREASED DYNAMIC RANGE  SYSTEM INSTABILITY LIMITATIONS WILL CAUSE INCREASED CLUTTER RESIDUE RELATIVE TO SYSTEM NOISE  THAT CAN CAUSE FALSE DETECTIONS #LUTTER MAPS  WHICH  ARE USED TO PREVENT FALSE DETECTIONS FROM CLUTTER  RESIDUE  WORK QUITE WELL ON FIXED RADAR SYSTEMS  BUT ARE DIFFICULT TO IMPLEMENT ON  FOR EXAMPLE  SHIPBOARD RADARS  BECAUSE AS THE SHIP MOVES  THE ASPECT AND RANGE TO EACH CLUTTER PATCH CHANGES  CREATING INCREASED RESIDUES AFTER THE CLUTTER MAP ! DECREASE IN THE RESOLUTION OF THE CLUTTER MAP TO COUNTER THE RAPIDLY CHANGING CLUTTER RESIDUE WILL PRECLUDE MUCH OF THE INTERCLUTTER VISIBILITY SEE LATER IN THIS CHAPTER   WHICH IS ONE OF THE LEAST APPRECIATED SECRETS OF SUCCESSFUL -4) OPERATION -4) RADAR MUST WORK IN THE ENVIRONMENT THAT CONTAINS STRONG FIXED CLUTTER  BIRDS  BATS  AND INSECTS  WEATHER  AUTOMOBILES  AND DUCTING 4HE DUCTING  ALSO REFERRED TO AS  ANOMA 
 Four PIN diodes provide an STC range of 63 dB with an insertton loss of  less than 0.6 dB.  The ARSR-3 is really two separate radars, each at a different frequency, operating into a  single antenna. Either system can be used separately (simplex operation) or both can be used  simultaneously (diplex operation). 
 (6) Suppose the oracle support of the siisT, and then the solution of ( 4)i s (si)T=Φi† Tri−λ/parenleftBig ΦiH TΦiT/parenrightBig−1 sign(siT),(si)TC=0, (7) where Φi† T=/parenleftBig ΦiH TΦiT/parenrightBig−1 ΦiH T,TCdenotes the complement of T.sign(·)is the signal function formulated as sign(si)=si |si|. (8) If the oracle support is accurate, then the ﬁrst term of ( 7) is the exact estimate of the signal. The second term of ( 7) is the bias that is brought by the regularized term of ( 4). 
 ARRAY   COMPOSITE CLUTTER  %#- AND PROPAGATION SCENARIOS  AND A TARGETS KINEMATICS AND 2#3 FEATURES ARE COVERED )NPUT AND OUTPUT DATA CAN BE SAVED  LOADED  AND EXPORTED TO OTHER SIMILAR APPLICATIONS OR FOR GENERAL USE IE  -3 /FFICE TOOLS FOR DATA ANALYSIS  ! SECOND PURPOSE IS TO PROVIDE A HANDY AND RELIABLE TOOL FOR TECHNICIANS AND ENGINEERS PERFORMING SYSTEM SETUP AT THE SITE OR ACCEPTANCE TESTS BY MEANS OF FIELD TRIALS  BY PROVIDING NOT ONLY THE SOFTWARE TOOLS AND MODELS BUT ALSO  WHERE REQUIRED  A DATABASE OF PREDICTION RESULTS  AND ALL OWING SIMPLE PARAMETRIC  EXCURSIONS THEREOF  WITHOUT THE NEED TO CONSULT A BULKY REFERENCE DOCUMENTATION )N BRIEF  THE MOST VALUABLE OUTCOMES THAT CAN BE OBTAINED WITH THE 273 ARE RADAR RANGE CALCULATION  RADAR ELEVATION COVERAGE DIAGRAMS IN CLEAR  %#- AND MULTI 
 TION FROM WATER BODIES 7HEN THE FOOTPRINT IS SMALLER  MORE VARIABILITY OCCURS 4HIS IS SHOWN IN &IGURE  FROM A STUDY OF THE VARIATION OF SCAT 
 By coherent it is meant that the phase of  the transmitted signal is preserved in the reference signal. The reference signal is the distin­ guishing feature of coherent MTI radar.  H the CW oscillator voltage is represented as A 1 sin 2rr/; r, where A 1 is the amplitude and  _(, the carrier frequency. 
  K D"3EA STATE    
 V oltage or current controlled attenuators, controlled via a D/A con - verter, typically provide improved resolution and lower insertion loss. Gain control attenuators are often incorporated within the receiver at both RF and  IF. RF attenuation is used to provide increased dynamic range in the presence of large  target returns. 
 The replica of the transmitted signal is "built in "  to the matched filter via the frequency-response function. If the input signal y,,(t) were the  DETECTION OFRADAR SIGNALS INNOISE373 wcgct,onapplying theSchwartz inequality tothenumerator ofEq.(10.10), Cl'"' 00 rIH(f) 12elfr IS(f) 12df ·-co ·-00RJ<_.:..::....-_-------- - ~orOOIH(f)12df 2 .- <YJ FromParseval's thcorcm.No 2(10.12) r'"IS(f)12df=rae,S2(t)dt=signalenergy=£ ....<'Y1 ..-00 Thereforc wehave 2£Rf<-­-No(10.13) (10.14) Thefrequency-response function whichmaximizes thepeak-signal-to-mean-noise ratioRf maybeobtained bynotingthattheequality signinEq.(10.11)applieswhenP=kQ,or H(f)=GaS*(J) exp(-j2nftd (10.15) wheretheconstantkhasbeensetequaltoI/Ga• Theinteresting property ofthematched filteristhatnomatterwhattheshapeofthe input-signal waveform, themaximum ratioofthepeaksignalpowertothemeannoisepower issimplytwicetheenergyEcontained inthesignaldividedbythenoisepowerperhertzof bandwidth No.Thenoisepowerperhertzofbandwidth, No,isequaltokToFwherekisthe Boltzmann constant, Toisthestandard temperature (290K),andFisthenoisefigure. lbematched filterandthecorrelation function. 
 McDonough, Synthetic Aperture Radar , New York: John Wiley and Sons, 1991.  5. G. 
 Tech. Rept. 155 SU- SEL-70-034, Stanford University, June 1970. 
  v  !VIAT 7EEK 3PACE 4ECHNOL   PP n  !PRIL     $ # #ROSS  $ $ (OWARD  AND * 7 4ITUS  h-IRROR 
 The use of ‘North-up ’displays for ASV did not become standard until ASV Mk. 13, in the 1950s. 3.3.4.2 Height tube The height tube had a ﬁxed time base and was permanently illuminated. 
 114Thetorqueonthefinscanbemadetobeinthe opposite direction tothetorqueontheantenna soastocauseanetreduction. Oneoftheattractions oftherigidradome isitsabilitytowithstand therigorsofsevere climate. Rimeicc,I.heprevalent typeoficingfoundintheArcticregion,haslittleornoeffect onmostradomes. 
 3, pp. 101-1 10, 1957.  220INTRODUCTION TORADAR SYSTEMS Asmentioned, thesolid-state transmitter hassomesignificant differences ascompared to theconventional tubetransmitter. 
 Large, correlated  ch07.indd   34 12/17/07   2:14:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 ENCE  ESPECIALLY IN RADARS WITH A LIMITED NUMBER OF COHERENT BURSTS ON TARGET  !NOTHER %##- TECHNIQUE TO BE CONSIDERED IS PULSE COMPRESSION BY MATCHED  FILTERING IT IS INTIMATELY RELATED TO THE WAVEFORM CODING DISCUSSED IN 3ECTION  0ULSE COMPRESSION    IS A PULSE RADAR TECHNIQUE IN WHICH LONG PULSES ARE TRANS 
 frequency and transmit another CPI of N pulses. Since most search radars are ambiguous in doppler, the use of different PRFs on successive coherent dwells will cause the target response to fall at different frequencies of the filter passband on the successive opportunities during the time on target, thus eliminating blind speeds. Each doppler filter is designed to respond to targets in nonoverlapping por- tions of the doppler frequency band and to suppress sources of clutter at all other doppler frequencies. 
 8)mounted inthe aircraft tobe controlled. Three principal advantages areoffered bysuch astep: 1.Range extension. The useful range against single small aircraft ofthesetdescribed here isabout 90miles; this can beincreased by the use ofbeacons tothe limit ofthe radar horizon (about 200 miles foranaircraft at25,000 ft).. 
 diagnoslics. anddummies Tablecourtesy RCA.Inc. Thecomputer mustbecapableofresponding totheimmediate demands ofhigh-priority taskswitho'utthrowing awaytheresultsofpartially completed lower-priority tasks.TheexeclI­ tireprogram mustrecognize thepresence ofahigh-priority taskandinitiateitproperly. 
 Hence a choice of W = 2VXTP and k' - 1 would ideally result in perfect cancellation. In practice, a sum pattern is chosen based on the desired beamwidth, gain, and sidelobes for the detection system requirements. Then the difference pattern A(O) is synthesized independently, based on the relationship required at design radar platform speed and allowable sidelobes. 
 Anactual FDP using one of{he preproduction sets isshown inposition ineastern France inFig. 7.15. The central antenna isthat of the main radar; the two that flank itare those ofBritish Type 13 heightfinders (Sec. 
 Dual polarization measurements at multiple wave - lengths provide even more information related to the eventual interpretation of the  size distributions, water-phase states, and hydrometeor (water or ice particles) types  in different classes of precipitation and clouds. The capabilities of multiple-parameter  meteorological radars are presented in Bringi and Hendry,14 Bringi and Chandra,24 and  in the collection of papers edited by Hall.151 Whereas longer-wavelength radars are  necessary for the study of severe storms, shorter wavelength millimeter-wave radars  are useful for sensing and probing newly developing clouds. Researchers often need  a wide range of these capabilities simultaneously. 
 17 .14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 Similarly, the relative velocity of point B on the opposite side of the beam is  v rV RR DV DB= =    = Ωλ λ 2 2 (17.14) Thus, the range of relative velocities in the scene is  ∆ Ω Ω Ω v r r rV D= − − = = ( ) 2λ (17.15) The range of doppler frequencies received from the scene is  ∆fV DV Dd= =2 2 λλ  (17.16) Thus, to avoid velocity ambiguity, the PRF must be at least 2 V/D. Writing  fV D tR R(min)(max)= =2 1 (17.17) we have  VtD R(max)=2 (17.18) Thus, the distance traveled by the platform during the time between pulses ( tR) must  be no more than D/2, and the SAR must transmit at least two pulses as its physical  antenna passes a stationary point in space. We also frequently want range-unambiguous operation, which implies  2 2V Dfc RR≤ <  (17.19) For example, if V = 180 m/s ( ≈ 350 kts), D = 2 m, and R = 150 km, then 180 Hz <  fR < 1000 Hz. 
 OPMENT OF PENCIL 
 TO 
 Step 6: The imaging ﬂow is shown in Figure 2. 3.2. Joint Sparse Constrained Optimization Model As mentioned in Section 2, a small amount of compressed sampled data is used to achieve high-resolution reconstruction of the scene in the single-channel independent CS approach. 
 Figure 3. Twenty elements MIMO linear array (in blue) obtained from a ﬁve elements transmitting linear array and a four elements receiving linear array. 3. 
 Also, for  an effective system, strategies have to be evolved to reduce the possibilities of target  identities being swapped, which can happen when targets move close together and  subsequently diverge. In particular, tracking algorithms have to attempt to cope with  the potentially large and fast change in the radar centroid as a target vessel turns. In the  worst case, this can amount to almost the length of the vessel, 300 meters or so, for a  large ship. 
 However, the probability  diminishes rapidly with increasing x, and for all practical purposes the probability of obtaining  an exceedingly high value of x ,is negligibly small.  The Rayleigh probabi~itydensit~ function is also of special interest to the radar systems  22INTRODUCTION TORADAR SYSTEMS 1k=­borwherekisaconstant. Arectangular, oruniform, distribution describes thephaseofarandom sinewaverelativetoaparticular originoftime;thatis,thephaseofthesinewavemaybe found,withequalprobability, anywhere from0to2n,withk=If2n.Italsoappliestothe distribution oftheround-ofT (quantizing) errorinnumerical computations andinanalog-to­ digitalconverters. 
 , 'ENERAL #LUTTER RETURNS FROM VARIOUS SCATTERERS HAVE A STRONG INFLUENCE ON THE DESIGN  OF A PULSE DOPPLER RADAR AS WELL AS AN EFFECT ON THE PROBABILITY OF DETECTION OF POINT TARGETS #LUTTER SCATTERERS INCLUDE TERRAIN BOTH LAND AND SEA   WEATHER RAIN  SNOW  ETC   AND CHAFF 3INCE THE ANTENNAS GENERALLY USED IN PULSE DOPPLER RADARS HAVE A SINGLE  RELATIVELY HIGH 
 A posteriori probability, 377-378  A priori probability, 378  A sandwich radome, 267  A-scope, 6, 354  Absorbers, and radar cross section, 553  Accuracy, FM-CW altimeter, 86-87  Accuracy, radar measurement, 400-411  Acoustic delay lines, MTI, 126  Acquisition radar, 153  Acquisition, in tracking radar, 177-178  Active-switch modulator, 215  AID converter, in MTI, 120  Adaptive antennas, 332-333  Adaptive array, in MTJ, 145  Adaptive' MTI, 142  Adaptive tracking, 180, 18S  Adaptive threshold, in MTD, 128  Adaptive video threshold (A VT), 392, 488  ADT, 153, 183-186, 392  Air-supported radomes, 265  Air-surveillance radar, 536-541  Air traffic control radar, 536-541  HF 0TH, 533  Aircraft, radar cross sections of, 39-44  Aircraft radomes, 267-268  Alpha-beta (11.-/J) tracker, 184-185  Altimeter, FM-CW, 84-87  Altimeter, and snow, 482  Altitude return, in pulse doppler radar, 145  Ambiguity diagram, 411-420  Amplitron, 209. 212 INDEX  Amplitude-comparison monopulse, 160-165  Amplitude fluctuations, in tracking radar,  167-168  AMTI, 140-147  and SAR, 528  AN/FPS-85, 213  computer control of, 324, 328  AN/SPS-48, 301-302  AN/SPY-1, 309  AN/TPN-19, 259-260  AN/TPS-59, 219  Angel echoes, 508-512  Angle fluctuations, 168-169  Angular accuracy, 409-411  of tracking radar, 167-172  Anomalous propagation, 450-456  Antenna scanning modulation, in MTI,  134-136, 144  Antenna temperature, 461, 464  Antennas, 223-337  adaptive, 332-333  aperture blocking in, 223-224, 239, 241, 266  aperture efficiency of, 288, 232  artificial dielectric lens, 249-252  Bayliss pattern for, 258  beam shape loss of, 58-59  az-el mount for, 271  Bootlace, 316  Butler beam-forming, 311-314  Cassegrain, 73, 240-242  constrained lens, 251 . 572 INDEX  Antennas:  cosccant-squared, 55-56, 258-261  coverage patterns of, 446-447  cross level of, 273  delta-a scanner, 298  dielectric Jens, 248-250  directive gain of, 224  double-curvature reflector, 259  Eagle scanner, 298  effective aperture of, 226-227  errors in, 262-264  far field of, 229  f/D ratio of, 239  reeds for, 236  field-intensity pattern of, 229  Fraunhofer region of, 229  Fresnel region of, 229  gain of, 224-226  ice, effect of, 240  lenses as, 248-254  low sidelobe, 227-228, 333, 549  Luneburg lens, 252-253  metal-plate lens, 250-252  mirror-scan, 242-244  motor drives for, 273  Mubis, 316  multimode feeds for, 164  multipath in, 442-447  n-bar scan, 178  near field of, 228  offset feed for, 239  organ-pipe scanner, 247-248  parabolic cylinder, 235-236  parabolic reflector, 235-243  parabolic torus, 236, 246-247  paraboloid, 235  pattern synthesis for, 254-258  polarization of, 227  polarization twist, 242-243  power gain of, 54, 225-226  radiation pattern of, 224, 228-235, 280-282  radomes for, 264-270  random errors in, 262-264  resonant frequency of, 179  scanning feed, 244-248  sidelobe radiation from, 227-228  sidelobes, in MTI, 145  in pulse doppler, 145-146  stabilization of, 270-273  surfaces for, 239-240  synthetic aperture, 517-529  systematic errors in, 262  Taylor illumination for, 257-258  torque fins for, 269 Antennas:  transreflector, 242  twist reflector, 242-243  Aperture blocking, 223-224, 239  in Cassegrain antenna, 241  by radomes, 266  Aperture efficiency, 228, 232  Aperture illuminations, 228--235  Area MTI, 148  Array antennas, 278-337  Array factor, 281-282  Arrays:  beam steering of, 282-285  beam steering computer for, 323 >  Blass beam-forming, 311-312  computer control of, 322-328  constrained feed for, 306-308  conformal, 3 30-3 31  corporate feed for, 285  digital phase shifters for, 287-288  diode phase shifters for, 288-291  Dolph-Chebyshev, 257  dome, 329-330  dual-mode ferrite phase shifter for, 295-296  electromechanical phase shifters for, 297-298  elements for, 305-306  endfire, 279  errors in, 318-322  feeds for, 306-310  ferrimagnetic phase shifters for, 291-297  ferroelectric phase shifters for, 297  flux drive ferrite phase shifter for, 295  Fox phase shifter for, 296-297  frequency-scan, 298-305  grating lobes in, 281, 283, 300, 332  hemispherical coverage, 328-329  Huggins phase shifters for, 303-305  hybrid-coupled phase shifter for, 289  latching ferrite phase shifter for, 293-294  lens, 308-309  limited scan, 334  linear, 279  loaded-line phase shifter for, 289  mixer-matrix feed for, 305, 308  MOSAR, 315  multifunction, 323  multiple beam, 310-318  mutual coupling in, 306  parallel-fed, 283, 285  parallel-plate feed for, 309  phase-frequency, 303, 334  phase-phase, 335  phase shifter quantization in, 321-322  phase shifters for, 286-298 . 
   3/,)$ 
 These can be undesirable in some military applications since they might  provide a distinctive feature for recognizing a particular radar.  An example of a traveling-wave tube designed for radar applications is the S-band Varian  VA-125A. It is a broadband, liquid-cooled TWT which uses a clover leaf coupled-cavity  slow-wave structure. 
 OUT EMITTING PULSES  BEARING  BKJ AND ELEVATION  EKJ OF THE JAMMER AS  WELL AS THE RELATIVE  STANDARD DEVIATIONS  RKJB AND RKJE  AND THE JAMMER 
 TO 
 ENGINE AIRCRAFT FLYING IN FORMATION.   42!#+).' 2!$!2   °ÎÇ ABOVE AND BELOW THE AVERAGE DOPPLER OF THE TARGET ! TARGET TYPICALLY HAS A SIGNIFICANT  RANDOM YAW  PITCH  AND ROLL MOTION EVEN ON A hFIXEDv HEADING 4IME PLOTS OF TYPICAL AIRCRAFT HEADING FOR AN AIRCRAFT FLYING A hSTRAIGHT COURSEv ARE OBSERVED TO HAVE TYPICAL RANDOM YAW MOTION THAT CAUSES SMALL CHANGES IN THE DOPPLER FROM EACH OF THE SCATTERING SURFACES OF THE AIRCRAFTS RIGID STRUCTURE 2ELATIVE TO THE AVERAGE DOPPLER OF THE AIRCRAFT  THE SCATTERING SURFACES LOCATED AWAY FROM THE AIRCRAFT CENTER WILL HAVE A SMALL INCREASING AND DECREASING RELATIVE DOPPLER FREQUENCY AS THE AIRCRAFT YAWS RIGHT AND LEFT 4HIS CAUSES A SPECTRAL SPREAD OF THE DOPPLER OF THE ECHO FROM THE RIGID BODY OF THE AIRCRAFT AND  IS ACCOMPANIED BY SPECTRAL LINES CAUSED BY MOVING PARTS ON THE AIRCRAFT #OMPONENTS OF THE TARGET ECHO FROM ROTATING OR MOVING PARTS OF THE TARGET CAUSE  DOPPLER LINES AT FREQUENCIES DISPLACED FROM THE AIRFRAME DOPPLER SPECTRUM 4HE PERIODIC AMPLITUDE MODULATION CAUSES PAIRS OF DOPPLER LINES SYMMETRICAL ABOUT THE DOPPLER OF THE AIRFRAME VELOCITY -OVING PARTS CAN ALSO CAUSE PURE FREQUENCY MODULATION THAT WILL RESULT IN A SINGLE SET OF DOPPLER LINES ON ONE SIDE OF THE AIRFRAME DOPPLER SPECTRUM  ! MAJOR SIGNIFICANCE OF THE DOPPLER MODULATION IS ITS EFFECT ON DOPPLER 
 9.15.—Long.range microwave antenna mount with two25-ft c3,1indrical reflectors. vation control ofthe beam except forinitial adjustment atthe time of assembling inthe field. Nor-frotary joints arenecessary inthewave- guide transmission lines. 
 AIRBORNE MTI  3.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 where q2 is the direction of the clutter cell with respect to the antenna pointing angle  when the second pulse is received and wr is the antenna scan rate. The subscripts on  the received signals Σi and ∆i indicate the pulse reception sequence. The difference pattern ∆ is used to generate an in-phase correction for scan - ning motion and a quadrature correction for platform motion. 
 Scanning ofthebeamisaccomplished by mechanical motion oftheplanartwist­ reflector.Movable ..--planar twistreflector'\-e--.-1 , I '.I "II I I , Irixedfeed'---- .....---"""~ ~"-AXIsofmirrormovement, ?B \Fixedparabolic reflector withparallel wires \ wavelength apartwhichareusuallysupported bylow-loss dielectric material. Theconstruc­ tionoftheparabolic reflector withthinparallelwiresmakesitpolarization sensitive. Thatis,it willcompletely reflectonesenseoflinearpolarization andbetransparent totheorthogonal senseofpolarization. 
 PUTER COMPUTATIONS  AND THIS HAS BEEN REVISED BY ADDING THE WORK OF 3PAULDING AND 7ASHBURN 4HE MAPS OF MEDIAN VALUES ARE ACCOMPANIED  BY DECILE VALUES TO INDICATE  DISTRIBUTIONS OVER DAYS OF THE SEASON ##)2 2EPORT  
 The Procedures of Phase Compensation Method The ﬂowchart of the proposed phase compensation method is shown in Figure 4. The steps of phase compensation method based on fast minimum-entropy are described as follows: Step 1 : Input the raw data-like data and utilize DCT method [ 17] to obtain the initial phase error ˆφ(m),lis the number of iterations. Step 2 : Compensate phase error by substituting φ(m)with ˆφ(m). 
 A duct which lies above the surface is called an  eleuutcd drrct. Surface ducts apparently are more usual than elevated ducts. To propagate  energy within the duct, the angle the radar ray makes with the duct should be small, usually  less than one deg~-ee.'~*~~ Only those radar rays launched nearly parallel to the duct are  trapped. 
 ,- 4HE THREE BASIC TECHNIQUES FOR ELECTRONIC BEAM STEERING ARE   FREQUENCY SCANNING     BEAM SWITCHING  AND   PHASE SCANNING WITH PHASE SHIFTERS /F THE THREE TECH 
 The stellar navigation accuracy depends on the emission’s time period, which for pulsars is with the high stability and accuracy. Pulsar navigation tracking system based on the Doppler frequency measurement model and pulsar timing and an interplanetary navigation and positioning system using pulsar signals is discussed in [6,7]. The pulsar signal processing algorithm that consists of epoch-folding, matched ﬁltering and detection is presented and evaluated in [ 8]. 
 ALONGTRACK (nmi) FIG. 17.7 Plan view of range-gate and doppler filter areas. Radar altitude, 10,000 ft; velocity, 1000 kn to right; dive angle, 10°; radar wavelength, 3 cm; PRF, 15 kHz; range-gate width, 6.67 ^s; gate, 4; doppler filter, at 2 kHz; bandwidth, 1 kHz; beamwidth, 5° (circular); main-beam azimuth, 20°; depression angle, 5°. 
 As defined above, however,  burnout of a diode can occur before the onset of physical destruction. An increase in the  receiver noise due to the effects of excessive RF energy can be just as harmful as complete  destruction; perhaps more so, for gradual deterioration of performance might not be noticed  as readily as would catastrophic failure. It is for this reason that some means of automatic  monitoring of receiver noise-figure is necessary if the radar is to be maintained in prime  operating conditions. 
 SPACE PRE 
 TO 
 DOPPLER DILEMMA WITH THE 3-02& PULSE CODE v IN  TH #ONF 2ADAR -ETEOROL  -UNICH  !-3    PP n  .ATIONAL 2ESEARCH #OUNCIL   7EATHER 2ADAR 4ECHNOLOGY BEYOND .EXRAD   7ASHINGTON  $# .ATIONAL  !CADEMY 0RESS    2 * +EELER  * ,UTZ  AND * 6IVEKANANDAN  h3 
 DRILLING VESSEL  WAS DESIGNED FOR  &)'52%   4(!!$ RADAR #OURTESY OF 2AYTHEON #OMPANY  .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°È EXCEPTIONAL STABILITY IN HIGH WINDS AND STORMS -EASURING  FT WIDE AND  FT LONG   THE VESSEL INCLUDES A POWER PLANT  BRIDGE AND CONTROL ROOMS  LIVING QUARTERS  STORAGE AREAS  AND ENOUGH FLOOR SPACE AND INFRASTRUCTURE TO SUPPORT THE 8 
 Teters, L. R., J. L. 
  3HOWN IN &IGURE   2!$!23!4 
 TO 
 QUENCY 
 A comparison is shown in  Fig. 10.5 or the detection probabilit.ies when the signal parameters are known completely  (coherent detector) and when the signal is known except for phase (envelope detector).24 The  abscissa is plotted as 2£/ NO instead of signal-to-noise ratio, where E is the signal energy and  NO is the noise power per hertz of bandwidth.  Although the coherent detector may be of superior sensitivity than other detectors it is  seldom used in radar applications since the phase of the received signal is not usually known. 
   PP n  $ECEMBER    ' . 4SANDOULIS  h4OLERANCE CONTROL IN AN ARRAY ANTENNA v  -ICROWAVE  *  PP n    /CTOBER   + ' 3HROEDER  h"EAM PATTERNS FOR PHASE MONOPULSE ARRAYS v  -ICROWAVES  PP n    -ARCH   2 3 'RISSETTI  - - 3ANTA  AND ' - +IRKPATRICK  h%FFECT OF INTERNAL FLUCTUATIONS AND SCANNING  ON CLUTTER ATTENUATION IN -4) 2ADAR v )2% 4RANS  VOL !.% 
 THE 
 90. S. T. 
 In addition to this, mul - tipath reflections from the ground, known as hot-clutter, will add a nonstationary  interference component to the image. The authors show the image degradation from  hot-clutter, the limited restoration that multi-channel spatial imaging and slow-time  STAP can provide, and how fast-time STAP can improve the final image quality. • Frequency agility . 
 SURED  4HE TECHNIQUE CAN BE EXTENDED TO MULTIPLE PASSES WITH PROPORTIONATE INCREASE  IN THE TEMPORAL BASELINE  LEADING TO QUITE REMARKABLE RESULTS 2EPEAT 
 In1904 aGerman engineer, Hulsmeyer, was granted apatent inseveral countries onaproposed way ofusing this property inanobstacle detector and navigational aidforships. In June 1922, Marconi strongly urged the use ofshort waves for radio detection. The principle ofpulse ranging which characterizes modern radar was first used in1925 byBreit and Tuve, oftheCarnegie Institution ofWashing- ton, formeasuring the height ofthe ionosphere. 
 ANTENNA SYSTEMS ARE SOMETIMES USED  WITH A CIRCULATOR ISOLATING TRANSMITTER AND RECEIVER THEIR PERFORMANCE IS SOMEWHAT POORER THAN THAT OF DUAL 
 LINK MODE CHARACTERIZED BY THE TRANSMITTER 
 The array factor is scanned by adjusting the frequency-   independent time-delay elements. All subarrays are steered in the same manner. The  total radiation pattern is the product of the array factor and the element factor. 
 In a military radar, a low-noise receiver car1 make the radar more susceptible to the effects  of deliberate electrorlic countermeasures (ECM). When practical, it may be preferred to delib-  erately employ a conventional receiver with modest sensitivity and to make up for the  reduced sensitivity by larger transmitter power. This is not the most economical way to build a  radar, but it does make the task of the hostile ECM designer more difficult. 
 TION IN THE  X  Y  PLANE  ALSO CALLED THE  BISTATIC PLANE 4HE BISTATIC TRIANGLE LIES IN THE  BISTATIC PLANE 4HE DISTANCE  , BETWEEN THE TRANSMITTER AND THE RECEIVER IS CALLED THE  BASE 
 BASED 3!2 DESIGN IS THE ANTENNA )T  DETERMINES RANGE SWATH COVERAGE AND REQUIRED MINIMUM TRANSMITTER POWER  AND HAS A MAJOR INFLUENCE ON RESOLUTION AND DATA RATE 4HE -AGELLAN ANTENNA  A  
                !                    
 The degradation of overall  sensitivity due to the A/D converter noise is given by  L(dB) = 10log10(1 + SADC/SIF) (6.42)FIGURE 6.16  IF sampling noise spectrumsBIF 0 fS fS/2 fIFAliased Input  NoiseAmplitude FrequencyBRA/D Con verter  Quantization Noise  + Additional Inter nal  NoiseA/D Con verter  Input Noise 10 log(SIF | SADC)(dB) ch06.indd   39 12/17/07   2:03:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 Range eclipsing. Range ghosts. High stability requirements due to range folding. 
 2010 ,48, 3212–3217. [CrossRef ] 3. Zhao, H.-S.; Xu, Z.-W.; Wu, J.; Wang, Z.-G. 
 For example, if the focused beam has 50 times the  power of an omni directional antenna with the  same transmitter pow er, the direc tional antenna  has a gain of 50 (or 17 Decibels).                                                      1  S. Kingsley and S. 
    EACH WITH A PEAK POWER OF  K7 AND AVERAGE POWER OF  K7 4HE 3 BAND 6! 
 37.Golay,M.J.E.:Complementary Series,IRETrans.,vol.IT-7,pp.82-87,April,1961. 38.MacWilliams. F.J.,andN.J.A.Sloane:Pseudo-Random Sequences andArrays,Proc.IEEE, vol.64, pp.1715-1729,December, 1976. 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°ÓÇ &OR SIMPLICITY  ASSUME THE "ENEDICT 
 It is due to the coherency and stability of the Main Pulse’s repetition period with time duration 0.033 s. The results of the observation show that most giant main pulses consist of several microbursts. The integrated intensity of pulsar ﬂux is measured with a time resolution of 6.4 ns, whereas the dynamic spectrum is plotted with 19.5 MHz spectral resolution and 25.6 ns time resolution. 
 S. Rotheram, “Ground wave propagation, parts 1 and 2,” IEE Proc., Pt. F , vol. 
 TIME SIGNAL PROCESSING APPLICATIONS !LTHOUGH THEY MIGHT BE COST 
 Buildings, towers.  and other structures give more intense echo signals than forests or vegetation because of the  presence of nat reflecting surfaces and "corner reflectors." Bodies or water, roads, and airport  runways backscatter little energy but are recognizable on radar PPI displays as black areas  amid the brightness of the surrounding ground echoes. A hill will appear to stand out in high  relief on a PPI. 
 All solar tidal constituents would be ambigu - ous with other height signals if the repeat period were an integral number of days. For  T/P, the time of day for each subsequent observation slips by about two hours. The  T/P repeat pass footprint location accuracy is better than ±1 km, a requirement that is  bounded by the cross-track gradient of the oceanic geoid. 
 Katzin, M., R. W. Bauchman, and W. 
 A sample 2CMV image after this stage is shown in Figure 4. Figure 4. (a) original 2CMV image; ( b) 2CMV image after Stage 1. 
 PATH ATTENUATION ! BRUTE 
 Equation (13.18)doesnotincludetheattenuation oftheradarenergybyprecipitation, whichcanbesignificant atthehighermicrowave frequencies andwhenaccurate measure­ mentsarerequired. Thetwo-way attenuation oftheradarsignalintraversing therangeRand backisexp(-2(XR), where(Xistheone-way attenuation coefficient. IJ(Xisnotaconstant over thepathR,thetotalattenuation mustbeexpressed astheintegrated valueoverthetwo-way path. 
 SECTION  R AND GIVEN BY REFERENCE  2UTLEDGE AND -UHA  )N THE FIRST MODEL SHOWN IN &IGURE   THE ANTENNA IS SET AT A HEIGHT OF  CM ABOVE  THE TARGET DIELECTRIC CYLINDERS OF  CM THICKNESS  RANGING IN SIZE FROM  M DIAMETER TO  M DIAMETER  4HE TARGET HAS A VALUE OF  D R OF  AND THE SOIL  DR    AND TANC       4HE RADIATED PULSE HAS A CENTER FREQUENCY OF  '(Z AND AN OUTPUT PULSE PEAK VOLTAGE OF  VOLTS 4HE RADAR RECEIVER HAS AN EQUIVALENT BANDWIDTH OF  -(Z TO  '(Z AND AN EQUIVALENT RECEIVER NOISE VOLTAGE OF  n VOLTS 4HE PROBABILITY OF DETECTION 0$  IS DERIVED FROM THE ERROR FUNCTION OF THE SIGNAL 
 94.Withers, M.J.:Frequency Insensitive Phase-Shift Networks andtheiruseinaWide-Bandwidth ButlerMatrix,Electronics Le((ers,vol.5,No.20,pp.416-198, Ocl.2.1969. 95.Chow,P.E.K.,andD.E.N.Davies: WideBandwidth ButlerMatrix,Electrollics Le((ers, vol.3, pp.252-253, June,1967. 96.Shelton, J.P.:Reduced Sidelobes forButler-Matrix-Fed LinearArrays,IEEETram.•vol.AP-17, pp.645-47, September, 1969. 
 The doppler shift from clutter will  be range dependent with an elevated radar since the doppler frequency is a function of the  elevation angle from the radar to the clutter cell. Thus more than one doppler measurement  may be necessary to compensate for the variation of the clutter doppler with range.  An MTI radar that measures the average doppler frequency shift of clutter qver a sampled  range interval and uses this measurement to cause the clutter mean-doppler-frequency to  coincide with the null of the MTI doppler-filter-frequency response over the remainder of the  range of observation is called a clutter-lock MT/. 
 The radar performance figure ofthe average settested was 14or15dbbelow the rated value forthe radar. Since aperformance-figure deficit of12dbresults incutting the maximum range ofthe setonaircraft byafactor of2(Fig. 15.1), poor radar performance was responsible for aloss ofmore than half the tactical usefulness ofthesystems tested. 
 Whentheuppertwoswitches areopen,the lowertwoareclosed,andviceversa.Notethatinthe"zero"phasestate,thephaseshiftis generally notzero,butissomeresidualamount¢o.Thusthetwostatesprovideaphaseof¢o and¢o+tl¢.Thedifference tl¢between thetwostatesisthedesiredphaseshiftrequired of themodule. Thearrangements ofFigs.8.5and8.6lendthemselves totheuseofsemiconductor diodes. Ferritephaseshiftersarealsooperated digitally, butinaslightlydifferent manner, asdescrihed later. 
 MTI AND PULSE DOPPLER RADAR 135  where k constant. The angular frequency spectrum or this time waveform is found by taking  its Fourier transform, which is  (l'.) ( 2 776t2 ) S0(f) = k J_ro exp -· 15 exp (-j2nft) dt  (4.31)  where k 1 = constant. Since this is a gaussian runction, the exponent is of the formf 2 /2a} where  a 1 = standard deviation. 
 STATE DISTRIBUTED TRANSMITTER  A MECHANICALLY AND ELECTRONICALLY SCANNED ROTATING ANTENNA  DIGITAL RECEIVERS  SPACE 
 The approach to selecting a waveform  with a suitable ambiguity diagram is generally by trial and error rather than by synthesis.  In summary, this section has considered some of the factors which enter into the selection  of the proper transmitted waveform. The problem of designing a waveform to achieve detec­ tion may be considered independently of the requirements of accuracy, ambiguity, resolution,  and clutter rejection. 
 V , Report 879-1, p 82. 26. “U.S. 
 Once the FET  has been defined, a combination of deposited dielectric films and metal layers is used  to form the passive components (such as metal-insulator-metal capacitors) and also  to interconnect all the elements of the circuit. Standard libraries of circuit elements  may include FETs (used as linear amplifiers, low-noise amplifiers, saturating power  amplifiers, or switches), resistors, capacitors, inductors, diodes, transmission lines,  interconnects, and plated ground vias. Transmit/Receive Module Characteristics. 
 Digital compensation can be used if synchronous detection and analog- to-digital (A/D) conversion are performed and the components are treated as complex phasors. Furthermore, the operations must be linear until the sum signal and difference signals have been processed by the hybrid amplifier. After thisDPCA COMPENSATIONGAINOPTIMIZED LINEARGAIN UNCOMPENSATEDIMPROVEMENT FACTOR (dB) . 
 Experimental Results 4.1. Simulation The point target simulations are performed in Figure 6. The point targets are distributed as the outline of an airplane. 
 82, no. 12, December 1994, pp. 1861–1872. 
 The properties of some of the  ohosphors which have been used in radar CRTs are listed in Table 9.1. The degree of image . 356 INTRODUCTION TO RADAR SYSTEMS  persistence required in a cathode-ray-tube screen depends upon the application. 
 The Russian company known as Federal State Unitary Enterprise, RPC Istok11  (usually shortened to Istok) has been productive in the development of MBKs for  radar. At X band, they report an MBK with 24 beamlets producing 200 kW peak  power, 17 kW average power, 6% bandwidth, an anode voltage of 26 kV, with a mag - net weighing 16 kg. At S band, one of their tubes with 36 beams had a peak power  of 600 kW, 12 kW average power, operated with 31 kV anode voltage, had a 6.5%  bandwidth, and a weight without magnet of 25 kg. 
 Frequency-domain doppler filter-  banks are of interest in some forms of MTI and pulse-doppler radar.  Filter characteristics of the delay-line canceler. The delay-line canceler acts as a filter which  rejects the d-c component of clutter. 
 At  lower frequencies, especially below 3 GHz, the Si BJT has been shown to be capable  of very high power levels for transistors. Amplifier design is realizable for frequencies  up through S band, where the tradeoff between device performance and overall sys - tem cost begins to reach a point of diminishing returns. The silicon bipolar transistor  technology is now very mature, but the demand for these high performance devices  is low because the production quantities required for radar systems is small relative  to commercial silicon electronic products. 
 VIVABILITY OF THE PENETRATING AIRCRAFT (OWEVER  WHEN THE DECOYS GROW TOO LARGE  THEY HAVE TO BE ENGAGED IF THEY ARE THOUGHT LARGE ENOUGH TO CARRY A WEAPON 0ENETRATION !ID 0ENAIDS  COULD BE USED BY INCOMING BALLISTIC MISSILES "-S   0ENAID  DECOYS ARE ONLY ONE OF SEVERAL POSSIBLE PENAIDS ! DECOY PROVIDES ANOTHER TARGET THAT THE DEFENSE HAS TO HANDLE IF THE DEFENSE CANNOT DISTINGUISH A DECOY FROM A RE 
 TION MODELS  !2%03 CONTAINS A SYSTEM PERFORMANCE RADAR MODEL  WHICH IS DISCUSSED IN THE NEXT SECTION !2%03 CONSIDERS RANGE 
 BEAM CLUTTER THAT DETECTION IS NOT LIMITED BY THE CLUTTER RETURN  -02& USUALLY HAS A SMALL AMOUNT OF PULSE COMPRESSION  TO    WHICH STILL MAY REQUIRE DOPPLER COMPEN 
 Quegan, “ Understanding Radar Systems ”, Scitech Publishing, Inc 1999, Page 11, ISBN 978 -1891121050     S. A. Hovanessian, “ Radar System Design and Analysis ” ,Artech House 1984, Page 5, ISBN: 0 -89006 -147-5      F. 
 Nine possible arrangements for mounting antennas are shown in Fig. 7.31. The one-axis  mount is the simplest. 
 DIMENSIONAL PHASE MONOPULSE HAS TWO PHASE CENTERS  A TWO 
 Several lines can be read in Figure 1.2.  Nevertheless not even he was in a position to awake enthusiasm and interest for Radar technology.   Beginning in 1922 successful Radar experiments with a wooden ship using 600  MHz were ca r- ried out by Tayler and Young of the US Naval Research Laboratory (NRL). 
 2 Constants for Linear Scattering Model (Summer)* ch16.indd   31 12/19/07   4:56:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 The basic construction assumed a graphite-epoxy-aluminum honey comb-sandwich configuration. Antenna systems have been studied and fabricated under the LSST program. Lockheed Missiles and Space Company (LMSC) has demonstrated, in a simu- lated zero-gravity environment, the technology for a large space-deployable antenna.52 LMSC fabricated a 22.5° sector of a 55-m-diameter wrap-rib parabolic antenna and deployed it in a ground-based zero-g facility. 
 1171-1183, September, 1966.  61. Becker, J. 
 : rf oe  &  we  " aon *  »'  Py  se HOW RADAR WORKS  Rowe, A. P., 22, 24, 39  Rushforth, L., Ir3  SCIENTIFIC AND INDUSTRIAL  aaa DEPARTMENT OF,  I  SCS-51, 160  Skiatron, 68, III  Skinner, Dr i. W. 
 ERROR 
 Galli, J. Joss, and U. Germann, “Three methods to determine profiles of reflectiv - ity from volumetric radar data to correct precipitation estimates,” J. 
 The separations between clutter larger than 10 m2 was be-  tween 135 and 675 m. For clutter which was greater than 0.1 m2, the patch sizes varied from  2 m to well over 300 m in length. The majority of these clutter-patch separations were less  than 30 m but a few exceeded 110 m. 
 IIIA,  pp. 539-544, 1946.  59. 
 5 Mc/s to 45 Mc/s, possibly because this made the design of the IF passband ﬁlters easier or to standardise the design. The IF frequency of ASV Mk. II and earlier centimetric AI radars was 45 Mc/s.The very early radar trials of RDF2 in 1936 [ 7]u s e da nE M It e l e v i s i o nr e c e i v e r as the IF ampli ﬁer. 
 TO 
 ThcefTective apcrturc width)' forseveralaperture distributions whichcanbecomputed analytically arcgivcnbclow: 1'l1raho/ic distrih/ltioll 4(1-~)X2A(x)=I -jjI---- ForL\=0 For~=0.5 ForL\=1.0 Cosinedistriblltion Triangular distributioll1'2=0.863D2 1'2=1.88D2 1'2=3.287D2 1tX A(x)=cos7i 1'2=1.286D2IxID<-­2(11.43) (11.44) 2A(x)=1-jjIxl },2=0.986D2IxID<­2 (11.45) Inverse probability, likelihood ratio,andaccuracy_ Themethod ofinverseprobability as described byWoodward.5 canbeusedasabasisfordetermining thetheoretical accuracies Issociated withradarmeasurements. Thelikelihood function alsocanbeusedforderiving measurement accuracy.9 Bothmethods resultinaccuracy expressions likethatofEq.(11.17). 11.4AMBI~UITY DIAGRAM5.10-12 Theambiguity diagram represents the response ofthematched filtertothesignalforwhichit ismatched aswellastodoppler-frequency-shifted (mismatched) signals.Although itisseldom usedasabasisforpractical radarsystemdesign,itprovides anindication ofthelimitations andutilityofparticular classesofradarwaveforms, andgivestheradardesigner general guidelines fortheselection ofsuitable waveforms forvariousapplications. 
 D" 7IDTH     &ALLOFF C   SUBPULSE DURATION C  D"  /CTAVEC   D"  /CTAVE 2ANGE 3AMPLING ,OSS  D"  D" &ILTER -ATCHING ,OSS  D"  D"4!",%    1UADRIPHASE 7AVEFORM 0ERFORMANCE 3UMMARY.   05,3% #/-02%33)/. 2!$!2   n°Óx 4IME 
 SURFACE MODELS  /NE MAJOR PROBLEM WITH ALL MODELS BASED ON SCATTERING FEATURE SIMULATIONS IS THE  LACK OF RELIABLE INFORMATION ABOUT THE SHAPES  SIZES  ORIENTATIONS  SPEEDS  LIFETIMES AND STATISTICS OF THE FEATURES THEMSELVES 4HUS  ALTHOUGH THERE IS OFTEN GUIDANCE FROM EITHER OBSERVATION OR THEORY  THE PREDICTIONS OF SUCH MODELS WILL BE BASED ON UNCERTAIN ASSUMPTIONS ABOUT THESE CRUCIAL PARAMETERS !S AN EXAMPLE  WATER SURFACE STABILITY ARGUMENTS PREVENT THE INTERIOR ANGLE OF A SHARPENING WAVE CREST FROM FALL 
 28–43, October 2001. 177. A. 
 TARGET RETURN  THEN PULSE 
    . 
 theorypredicts considerable signalfadesduetointerference between theseveralmodes.Fades canbeoftheorderof20dB,Inoneexample. itwasshownthatthefadingisstrongly dependent ontheradarandthetargetheights,andthatforcentimeter wavelengths thefading occursatintervals offromtwotothreemiles. Theheightoftheevaporation duct.fromwhichthepropagation conditions canhein­ ferred,canbereadilycalculated frommeasurements ofthesurfacewatertemperature and.at someconvenient height.theairtemp·erature. 
 4.3. InSAR Data Validation Statistical analysis of the mean standard deviations is conducted to assess the internal precision of subsidence rates of subsidence rates. More than 83.81% of PS points obtain a standard deviation of less than -6 mm/yr, proving that applying SBAS-InSAR method to derive subsidence rates is reliable. 
 Their sun-synchronous orbits are less than optimum for most  altimetric applications, due primarily to the fact that four of the eight dominant  tidal constituents are sun-synchronous.63 These orbits are also at lower altitudes  than the T/P orbit, which implies that orbit maintenance maneuvers must be more  frequent, thus compromising precision orbit determination. During a portion of its  mission, the orbit of ERS-1 was rephased to a long repeat period (176 days). That  long repeat period generated a relatively dense surface sampling grid useful for  estimating sea ice cover, geodesy, and bathymetry. 
 For centimetre waves concentric cable causes too much less even on short lengths, and the connexion between transmitter and ‘aerial’ is a wave-grade of rectangular section made of copper sheet (d). It can be bent, and it can be flared into a horn to project the waves against a metal reflector.  plete 2ee drawings are merely illustrative, and are not to be considered accurate in ‘. 
 The transmit duty  cycle  is the transmit pulse width divided by the IPP. The train of pulses is called the  coherent processing interval  (CPI). The coherent processing forms a bank of doppler  FIGURE 4.6  Example of range gates with 50% overlap equally spaced in the interpulse period. 
 TYPE RADIATORS FOR A TOTAL OF  ELEMENTS /N TRANSMIT  SUBARRAYS WERE COMBINED IN PAIRS  AND  SUCH PAIRS GAVE A TRANSMIT APERT URE OF  RADIATORS  4HE PHASE SHIFTERS FED DIRECTLY INTO WAVEGUIDE RADIATORS  HAD  BITS  AND WERE OF THE NONRECIPROCAL  LATCHING GARNET CONFIGURATION ! LATER VERSION WAS DESIGNED FOR LOW SIDELOBES 4HE SUBARRAY SIZE HAD TO BE REDUCED TO  ELEMENTS TO AVOID QUANTIZATION LOBES  AND SIMILARLY  THE PHASE SHIFTER HAD TO BE REFINED BY DRIVING IT WITH  
 Robertson, J. W., and F. J. 
 A height accuracy of . (a) FIG. 20.2 Exemplar 3D radars, (a) S713 Martello stacked-beam 3D radar (Courtesy Marconi Company). 
 The range dimension represents the unambiguous range interval Ru, and  the frequency dimension represents the PRF interval, with the main-beam clutter,  altitude-line, and sidelobe clutter regions clearly discernible. In both waveforms,  the main-beam clutter return is positioned to DC through clutter positioning via an FIGURE 4.4  Sidelobe clutter-clear regions versus target aspect angle. Note the target is at the center of the  plot with the radar platform on the circumference.CASE COLLISION COURSE RADAR CLEAR REGION NOSE TAIL TARGETSIDELOBE CLUTTER REGION 180°165°150°135°120°105° 75° 60° 30° 15° 0°VR VTVT/VR 1 12 23 34 4VR - RAD AR AIRCRAFT VELOCITY VECT OR  VT - TARGET VELOCITY VECT OR1 0.8 0.6 0.4 VR TARGETASPECTANGLE CASE ch04.indd   7 12/20/07   4:51:58 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 NOISE RATIO  40  VARIES DRAMATICALLY WITH STRADDLE AND ECLIPSING LOSSES FOR EXAMPLE  SEE &IGURE   4HE FUNCTION TO BE OPTIMIZED IS A THRESHOLDED VERSION OF 40 K OR J&)'52%  -EDIUM 
 H. Ward, “The RAMP PSR, a solid-state surveillance radar,” presented at IEE International  Radar Conference, London, October 1987. ch11.indd   36 12/17/07   2:25:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 7AVE &REQUENCIES  !LL THE MEASUREMENTS DESCRIBED  ABOVE WERE MADE AT MICROWAVE FREQUENCIES BETWEEN 5(&  -(Z  AND +A BAND   '(Z  (IGH 
 The photograph of a representative MMIC chip, shown in Fig. 5.10, is a 12-W power amplifier chip pair that operates at S band. The final stages of this partic- ular design use FETs with a total of 30-mm gate periphery. 
 The reduction in the extent of the seareturn is clear, together with a reduction in the intensity of land returns (e.g. ﬁgure 4.35(e) and (f)). The receiver IF bandwidth of ASV Mk. 
 W., et al.: "Flight Performance Handbook for Orbital Operations," John Wiley & Sons, New York, 1961. 17. Hord, R. 
 Although these processing techniques are described else- where (Chaps. 15 to 17 and 21), they determine the basic stability requirements of the receiver. The first local oscillator, generally referred to as a stable local oscillator (stalo), has a greater effect on processing performance than the transmitter. 
 V.  Schensted: Bistatic Radar Cross Sections of Surfaces of Revolution. J. 
 SON MONOPULSE ! FEEDBACK LOOP MINIMIZES THE RECEIVED DIFFERENCE BEAM SIGNAL BY MECHANICALLY STEERING THE ANTENNA TO KEEP THE NULL AND THE CORRESPONDING SUM BEAM PEAK  ON TARGET 4HERE ARE NUMEROUS WAYS TO REALIZE AMPLITUDE MONOPULSE BEAMS IN A REFLECTOR  ANTENNA DESIGN  BUT MOST DESIGNS GENERALLY FALL INTO TWO CLASSES   MULTIFEED AND    MULTIMODE -ULTIFEED DESIGNS USE COMBINING NETWORKS TO GENERATE DIFFERENTIAL  FEED DISTRIBUTIONS )N ITS SIMPLEST FORM  AN AZEL  MULTIFEED MONOPULSE FEED ARRAY CAN BE REALIZED AS A FOUR 
 Some readers have undoubtedly been confronted by the highway police using  the CW doppler radar to measure the speed of a vehicle. Ground penetrating radar  has been used to find buried utility lines, as well as by the police for locating buried  objects and bodies. Archeologists have used it to determine where to begin to look  for buried artifacts. 
 DIMENSIONAL TACTICAL RADAR FAMILY DEVELOPED BY THE .ORTHROP 'RUMMAN #ORPORATION &IGURE   4HE !.403 
 GPS Solut. 2015 , 20, 125–133. [ CrossRef ] 18. 
 They all can give the correct values for use in the radar eqilation provided ~lic  asstlmptions used by each author are understood.  The original false-alarm time of Marcum'' is different from that used in this text. He  defined it as the time in which the probability is 112 that a false alarm will not occur. 
 Element-Phasing Calculations.  A computer is usually required to perform the  steering computations for a phased array antenna. It can compensate for many of the  known phase errors caused by the microwave components, the operating environ - ment, and the physical placement of the elements. 
 Iftheradarradiates onesenseofcircularpolarized energy,. it cannot accept the backscattered echosignal from a sphere or a plane sheet, since the direction  ofthe polarization is reversed on reflection; that is, if right-hand circular polarization is trans-  mitted, spherical raindrops reflect the energy as left-hand circular polarization. If the same  antenna is used for both transmitting and receiving, the antenna is not responsive to the  opposite sense of rotation and the echo energy will not appear at the receiver. 
 RESPECTING RADAR SYSTEM SHOULD MAKE THE OPERATOR AWARE OF  HIGHER NOISE LEVELS DUE TO JAMMING EVEN THOUGH THEY MAY NOT BE VISIBLE ON THE #&!2 DISPLAY THE ACT OF PERFORMING #&!2 SHOULD NOT EXCLUDE THE OPERATOR FROM KNOWING THAT JAMMING IS PRESENT AND THAT THE DETECTION THRESHOLD HAS BEEN RAISED Ó{°£äÊ "* 
 PRESSION IS TO BE IMPLEMENTED WITH A SINGLE -4) FILTER  IT IS NECESSARY TO USE ADAPTIVE TECHNIQUES TO ENSURE THAT THE CLUTTER FALLS IN THE -4) REJECTION NOTCH !N EXAMPLE OF SUCH AN ADAPTIVE -4) IS 4!##!2   ORIGINALLY DEVELOPED FOR AIRBORNE RADARS )N MANY  APPLICATIONS  THE ADAPTIVE -4) WILL FURTHER HAVE TO TAKE INTO ACCOUNT THE SITUATION WHERE MULTIPLE CLUTTER SOURCES WITH DIFFERENT RADIAL VELOCITIES ARE PRESENT AT THE SAME RANGE AND BEARING 5SUALLY THE DOPPLER SHIFT OF CLUTTER RETURNS IS CAUSED BY THE WIND FIELD  AND EARLY  ATTEMPTS OF COMPENSATING IN THE -4) HAVE VARIED THE COHO FREQUENCY SINUSOIDALLY AS A FUNCTION OF AZIMUTH BASED ON THE AVERAGE WIND SPEED AND DIRECTION 4HIS APPROACH IS &)'52%  !VAILABLE .YQUIST BANDWIDTH VS !$ CONVERTER SAMPLING RATE                           "$  
 (ed.): "Modern Radar: Analysis, Evaluation and System Design," John Wiley & Sons, New York, 1966. 5. Barton, D. 
 LOOKING BEAMS AT n  n  AND n  INCIDENCE   THUS SWEEPING OUT STRIPS OF COVERAGE AS THE SPACECRAFT MOVES ALONG ITS ORBIT 4HE SCATTEROMETER IS FULLY POLARIZED ((  (6  6(  AND 66  0EAK TRANSMITTED POWER IS ^ 7  PULSE LENGTH IS  MS  SUFFICIENT TO SUPPORT SEA SURFACE  R    OVER THE  RANGE  D" TO n  D" 2ESOLUTION IS MODEST  AT  ^ KM 4HE SCATTEROMETER AND RADI 
 For radar applications, anelectronic voltage regulator isthemost satisfactory type. Although itweighs more than asimple mechanical regulator, an electronic regulator should beemployed onsystems delivering 75o va ormore. Electronic Voltage Regulators.—An electronic voltage regulator consists ofavoltage-sensitive element, anamplifier, and anoutput stage that supplies d-cexcitation forthe generator oralternator field. 
 214-3, May 11, 1988. CHAPTER 23 METEOROLOGICAL RADAR Robert J. Serafin National Center for Atmospheric Research* 23.1 INTRODUCTION As this handbook is being written, dramatic changes are taking place in the field of radar meteorology. 
 The internal motions  of the storm can also widen the spectrum of the precipitation clutter. At the higher microwave  frequencies, where precipitation can be a bother, it is difficult to achieve effective MTI because  of the reduced blind speeds (Sec. 4.2) and the increased spread of the clutter spectrum. 
 If each of the above radars were thought of as providing some  radar function, then a multifunction radar is one designed to perform more than one  such function—usually performing one function at a time on a time-shared basis. There are many other ways to describe radars, including land, sea, airborne, space - borne, mobile, transportable, air-traffic control, military, ground-penetrating, ultra - wideband, over the horizon, instrumentation, laser (or lidar), by the frequency band at  which they operate (UHF, L, S, and so on), by their application, and so forth. 1.3 INFORMATION AVAILABLE FROM A RADAR Detection of targets is of little value unless some information about the target is obtained  as well. 
 564 INTRODUCTION TO RADAR SYSTEMS  94 GHz by about 5 dB (on average) than horizontal polarization, which is the opposite to the  experience at microwaves. (It should be cautioned that the few measurements available were  taken at low grazing angle and over a limited range of wind speeds.)  As with ·trees and grass, the value of a0 for snow increases with frequency and grazing  angle.77•78•102 Crusted snow (that which has melted and refrozen), produces higher values of  a0 at 35 GHz and 94 GHz than wet snow, grass, or trees.  At microwaves the backscatter from rain can be explained according to the Rayleigh  scattering model with the reflectivity varying as the fourth power of the frequency (Sec. 
 16.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Ground Echo Richard K. Moore The University of Kansas 16.1 INTRODUCTION Radar ground return is described by s 0, the differential scattering cross section, or  scattering coefficient (scattering cross section per unit area), rather than by the total  scattering cross section s  used for discrete targets.1 Since the total cross section s  of  a patch of ground varies with the illuminated area that is determined by the geometric  radar parameters (pulse width, beamwidth, etc.), s 0 was introduced to obtain a coef - ficient independent of these parameters. Use of a differential scattering cross section implies that the return from the ground  is contributed by a large number of scattering elements whose phases are independent. 
 Usually the PRF lower bound is set so that there is a margin  of 25% or more with respect to this constraint. In an airborne SAR, the PRF constraint is derived to satisfy the doppler bandwidth,  from which follows the maximum range that the radar can operate without introduc - ing ambiguities. However, by default, the minimum range for a space-based SAR is  its orbital altitude, usually 600 km or higher. 
 294-297, Oct. 27-29, 1969, IEEE Publication 69 C 31-AES.  46. 
 415, 1977. 28. Lipa, B.: Derivation of Directional Ocean-Wave Spectra by Integral Inversion of Second-Order Radar Echoes, Radio Sd., vol. 
 Although a radiation  jlattetli with tlie t~arrowest beamwidth for a given sidelobe level seems a reasonable choice for  radar. it is seldoln employed since it cannot be readily ichieved with practical antennas wllere  I~igli gain and low sidelobes are desired. As the antenna size increases, the currents at the end  of the aperture become large compared with the currents along the rest of the aperture, and the  radiation pattern becomes sensitive to the edge excitation. 
 Were this curvature only afewtimes greater, itwould equal thecurvature ofthe earth itself, and itwould bepossible foraray tobend around the earth without leaving the surface; inother words, there would benohorizon. Whatever misgivings wemay have about the use ofthe word “ray” in this connection, itwould not besurprising ifsome interesting departure from standard microwave propagation were tomanifest itself under such conditions. Refractive index gradients oftherequisite strength (5parts in10sper ft)can beproduced under some conditions bytemperature gradients alone. 
 IRE, vol. 44,  pp. 1572-1581, November, 1956. 
 CLUTTER RATIO  DETERMINES DETECTABILITY .OTE THE ^ D" VARIATION IN TARGET ECHO STRENGTH DUE TO CHANGES IN THE IONOSPHERE OVER  SECONDS. 
 BAND FOCAL 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 What is more surprising is the day-to-day variability, even at mid-latitudes, which  impacts significantly on HF radar performance. The inability to predict reliably even  a day in advance is a serious consideration in radar design and scheduling. 
 Additional reverse biasing may be introduced as a result  of the voltage drop induced by current flow across parasitic resistance of the base  or emitter-bias return, and in common base operation, this will result in degraded  power gain. ch11.indd   19 12/17/07   2:25:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Since the difficulty remains that thetwo sets ofpulses must “tide through” each other, some method would have tobefound for distinguishing thetwo trains. This difficulty canbeavoided bytransmit- ting one master pulse and one train of“phase-shifted” pulses oneach radar cycle and, atthereceiving station, constructing thereference train byshock-exciting anoscillator with themaster pulse.. 698 RADAR RELAY [SEC. 
 Jackson, “The Apollo lunar sounder radar system,” Proceedings of the IEEE , vol. 62,   pp. 769–783, 1974. 
 Ê, , 'ENERAL  #HARACTERISTICS  AND  #APABILITIES  !LTHOUGH SKYWAVE PROPAGATION  PROVIDES THE UNIQUE CAPABILITY OF LOW ALTITUDE TARGET DETECTION AT RANGES OF THOUSANDS  OF KILOMETERS  OTHER FORMS OF PROPAGATION AT (& CAN BE EXPLOITED IN RADAR APPLICATIONS  "Y FAR THE MOST COMMON OF THESE IS  GROUND WAVE OR  SURFACE WAVE PROPAGATION  WHICH  IS MOST EFFECTIVE FOR VERTICALLY POLARIZED RADIOWAVES TRAVELING  OVER HIGHLY CONDUCTIVE  SURFACES SUCH AS SEAWATER )N ADDITION  THERE ARE APPLICATIONS FOR WHICH LINE 
 CALLED BLIND SPEEDS 0ULSE DOPPLER RADAR  4HERE ARE TWO TYPES OF PULSE DOPPLER RADARS THAT EMPLOY EITHER  A HIGH OR MEDIUM 02& PULSE RADAR 4HEY BOTH USE THE DOPPLER FREQUENCY SHIFT TO  EXTRACT MOVING TARGETS IN CLUTTER !  HIGH 02& PULSE DOPPLER RADAR  HAS NO AMBIGUI 
 VI 4.1 Requirement for ASV Mk. VI In early 1944, ASV Mk. VI (ARI 5568) went into service, followed soon by ASV Mk. 
 32. F. J. 
 RECEIVER RANGE MEASURED BY A BISTATIC RADAR IS THE RANGE  SUM 24   22  -ETHODS FOR MEASURING THIS SUM ARE GIVEN IN 3ECTION  4HE RANGE  SUM LOCATES THE TARGET SOMEWHERE ON THE SURFACE OF AN ELLIPSOID WHOSE FOCI ARE THE TRANSMITTER AND RECEIVER SITES 4HE INTERSECTION OF THE BISTATIC PLANE AND THIS ELLIPSOID  &)'52%   "ISTATIC RADAR NORTH COORDINATE SYSTEM FOR TWO DIMENSIONS   ESTABLISHING THE BISTATIC PLANE 4HE BISTATIC TRIANGLE LIES IN THE BISTATIC PLANE. ÓÎ°{  2!$!2 (!.$"//+  PRODUCES THE FAMILIAR ELLIPSES OF CONSTANT RANGE SUM  OR  ISORANGE CONTOURS  ! USEFUL  RELATIONSHIP IS THAT THE BISECTOR OF THE BISTATIC ANGLE IS ORTHOGONAL TO THE TANGENT OF THAT  ELLIPSE AT THE TARGET 4HE TANGENT IS OFTEN A GOOD APPROXIMATION TO AN ISORANGE CONTOUR WITHIN THE AREA COMMON TO THE TRANSMIT AND RECEIVE BEAMS 7HEN THE BISTATIC RADARS RECEIVING ANTENNA IS A PHASED ARRAY  AND THE ARRAY NORMAL  IS ALSO NORMAL TO THE BASELINE   P 2 IS MEASURED DIRECTLY BY THE ANTENNA IN ANY BISTATIC  PLANE 4HIS FORTUITOUS SITUATION IS CAUSED BY  CONIC DISTORTION  WHICH IS INHERENT IN ANY  PHASED ARRAY ANTENNA (OWEVER  WHEN THE ARRAY NORMAL IS NOT NORMAL TO THE BASELINE  OR WHEN THE RECEIVING ANTENNA IS MECHANICALLY STEERED OR SCANNE D  P 2 IS NOT MEASURED  DIRECTLY /FTEN $/! MEASUREMENTS ARE TAKEN INOR CONVERTED TOAZIMUTH AND ELEVA 
 This is not always the best filter to use for time-domain waveforms  where the fidelity of the output may be a requirement. The Wiener filter separates signals based on their frequency spectra. The gain of  the Wiener filter at each frequency is determined by the relative amount of signal and  noise at that frequency: The Wiener and matched filter must be carried out by convolu - tion, making them extremely slow to execute. 
 56. Andreone. V. 
 F. Ross: A New Radar Concept for Short Range Application, IEEE Int. Radar Conf., 1975. 
 Gen­ erally, there is less attenuation at· S band the higher the radar antenna or the target  altitude.30·-'1 At X hand (J cm wavelength). the coupling to the duct is stronger and the  average (one-way) attenuation was reported as 0.45 dB/nmi.-'7 Unlike S band, the attenuation  at X hand was less at low antenna and target heights (J to 5 m). giving stronger signals and  greater ranges than antennas and targets at heights up to 30 m: which is a further indication of  effective trapping at the higher frequencies. 
 Walsh, “Pulse-to-pulse correlation in satellite radar altimetry,” Radio Science , vol. 17,   pp. 786–800, 1982. 
 New York, 1970.  36. Harton. 
 PUTED   )1  AND CONVERTED TO ANALOG VIDEO IN A DIGITAL 
 The illput signal is applied across the irlteractiori gap of the first cavity. Low-power tubes  rnigltt contain a grid structure at the gap to provide coupling to the beam. In high-power  tubes. 
 For many OTHR purposes, it suffices  to employ a ray-theoretic representation of the radiowave field. Ray-tracing techniques  fall into two categories: analytic and numerical. Analytic methods are fast but rely on fit - ting parametric models to the electron density profiles and are, hence, of limited use for  operational applications where accuracy is critical. 
          . Ó£°Óä  2!$!2 (!.$"//+  Ó£°xÊ *,Ê-9-/ 
 25.Ternes.C.L.:Sidelobe Suppression inaRange-Channel Pulse-Compression Radar,IRETrans..vol. MIL-6.pp.162-169. April. 
 Krolik and R. H. Anderson, “Maximum likelihood coordinate registration for over-the- horizon radar,” IEEE Trans. 
 SURVEILLANCE RADARS AND RADARS CALLED WIND PROFILERS  THAT MEASURE THE SPEED AND DIRECTION OF THE WIND 'ROUND 0ENETRATING 2ADAR '02   DISCUSSED IN #HAPTER   IS AN EXAMPLE OF WHAT  IS CALLED AN ULTRAWIDEBAND 57"  RADAR )TS WIDE SIGNAL BANDWID TH SOMETIMES COV 
 DEPENDENT POWER SYSTEMAVOIDS THE SHADOW OF THE %ARTH ALMOST ALWAYS FOR ALMOST ALL SEASONS #ERTAIN APPLICATIONS ARE PARTICULARLY WELL 
 33, pp. 100–114, 1995. 133. 
 In a low-duty-cycle radar, range tracking is similar to pulse radar tracking in that split-gate tracking is used. In a high-duty-cycle radar, continuously variable PRF ranging or linear-FM ranging may be used. In a pulse doppler radar, the tracked range is usually ambiguous, so that provisions must be made to track through multiple interpulse periods and during eclipse (that is, when the target return overlaps the transmitted pulse). 
 Full quadrature polarization is one of the mode options. The only payload instrument  is the radar, so the spacecraft is designed for a sun-synchronous dawn-dusk orbit,  11-day repeat. Several years after the launch of TerraSAR-X, it will be joined by a  companion, Tandem-X, which is meant to be a functional copy.24 These two will co- orbit as a closely coordinated pair to support a variety of bistatic and interferometric  applications. 
 OFF   PULSE POSITION  PHASE SHIFT  AND FREQUENCY SHIFT MODULATION ARE COMMONLY USED  ,INKS MAY BE UNIDI 
 MENT IN AN ARRAY HAS BEEN DISCUSSED AND HAS BEEN SHOWN TO VARY AS THE ARRAY IS SCANNED  !N ARRAY THAT IS MATCHED AT BROADSIDE CAN BE EXPECTED TO HAVE AT LEAST A  6372 AT A n ANGLE OF SCAN 4O COMPENSATE FOR THE IMPEDANCE VARIATION  IT IS NECESSARY TO HAVE A COMPENSATION NETWORK THAT IS ALSO DEPENDENT ON SCANNING 3MALL !RRAYS  4HE ELEMENT PATTERN IS THE BEST SINGLE INDICATOR OF IMPEDANCE  MATCHING IN A SCANNING ARRAY /NE WAY OF DETERMINING THE ELEMENT PATTERN IS TO BUILD A SMALL ARRAY ! CENTRAL ELEMENT IS EXCITED  AND ALL OTHER ELEMENTS ARE TERMINATED 4HE PATTERN OF THIS CENTRAL ELEMENT IS THE ACTIVE ELEMENT PATTERN $IAMOND  HAS EXAMINED  THE NUMBER OF ELEMENTS REQUIRED IN A SMALL ARRAY TO PROVIDE A REASONABLE APPROXIMA 
 IEEE.)  Nonideal equipment. The transmitter power introduced into the radar equation was assumed  to be the output power (either peak or average). However, transmitting tubes are not all uniform  in quality, nor should it be expected that any individual tube will remain at the same level of  performance throughout its useful life. 
 Sincefilm records lightintensity, thesignofthesignalamplitude willbelostifthesignalaloneis recorded onthefilm.Toretainthesignoftheamplitude, adcbiasequaltoorgreaterthanthe mostnegative signalexcursion isaddedtothesignal.(Itisthisbias,plustheoffsetfrequency described below,whichcausesthefactorof2tobeinserted inEq.(14.12).) Thesignalreceived fromasinglescatterer willappearasavaryingdoppler-frequency due totherelativemotionastheantenna scansby.Thedoppler frequency isinitiallyofhighvalue, decreases tozerobeat,andthenincreases again.Whenthissignalisrecorded onfilmthe resulting intensity modulation isaone-dimensional hologram, orFresnelzone-plate, andhas focusing properties. Ifthefilmwereilluminated byacoherent, collimated beamoflightlike thatfromalaser.afocusedtarget-image willbeobtained. Figure14.6showsthebasicarrange­ mentofanopticalprocessor. 
 TIVELY RECEIVES A GREATER CHARGE 4HE LATE GATE SEES ONLY A SMALL PORTION OF THE PULSE  RESULTING IN A SMALLER NEGATIVE CHARGE 3UMMING THE CAPACITOR VOLTAGES RESULTS IN A NEGATIVE OUTPUT /VER A RANGE OF ERRORS OF APPROXIMATELY  o  OF THE TARGET 
 G. Hansen13 © IEEE 1970 ) FIGURE 7.5  Detection performance of the analog moving-window detector for the no- fading case ( after V . G. 
 OF 
 L. Sweet, “The SASS scattering coef - ficient ó0 algorithm,” IEEE Journal of Oceanic Engineering , vol. OE-5, pp. 
   )NTERNATIONAL (YDROGRAPHIC  /RGANIZATION  -ONACO  ( (ECHT  " "ERKING  ' "ÓTTGENBACH  - *ONAS  AND , !LEXANDER   4HE %LECTRONIC #HART  ND %D   ,EMMER  .ETHERLANDS ')4#    h/PERATIONAL USE OF !)3 v -ODEL #OURSE   )NTERNATIONAL -ARITIME /RGANIZATION  ,ONDON     h4HE TECHNICAL  CHARACTERISTICS FOR A UNIVERSAL SHIPBORNE AUTOMATIC IDENTIFICATION SYSTEM !)3   USING TIME DIVISION MULTIPLE ACCESS IN THE MARITIME MOBILE BAND v )45 2ECOMMENDATION  - 
 and A. Wilczek: CF A Tube Enables New-Generation Coherent Radar, Microwave J.,  ml. 16. 
 FIELDv 4HE SELF 
 Therefore, the cross-range resolution in KA-DBS is doubled compared with the conventional DBS imaging algorithm. Real-data results show that the proposed algorithm performs well with short dwell time. The rest of this paper is organized as follows: in Section 2, the DBS architecture is discussed. 
 An alternative approach is the solution of the integral equations governing the distribution of induced fields on target surfaces. The most useful approach at so- lution is known as the method of moments, in which the integral equations are reduced to a system of linear homogeneous equations. The attraction of the method is that the surface profile of the body is unrestricted, allowing the com- putation of the scattering from truly tactical objects. 
  ARE ITS FACETTED AERODYNAMICALLY POOR  SURFACE PROFILE AND ITS &)'52%   ,OCKHEEDS 32 
 TION ON THE ABSORBING PROPERTIES OF PRECIPITATION !TTENUATION BY 7ATER 6APOR  !TMOSPHERIC WATER VAPOR MAY TAKE ON VALUES UP TO   GM AND GIVE VARIABLE ATTENUATION DEPENDING ON THE WATER VAPOR CONTENT (OWEVER   AT TYPICAL WEATHER RADAR WAVELENGTHS LONGER THAN  CM  THE ATTENUATION IS LESS THAN A FEW HUNDREDTHS D"KM AND IS USUALLY IGNORED 'ASEOUS OXYGEN CONTRIBUTES ONLY A MINOR ABSORPTION EFFECT AT THESE CENTIMETER WAVELENGTHS AND IS ALSO USUALLY IGNORED !TTENUATION IN #LOUDS  #LOUD DROPLETS ARE REGARDED HERE AS THOSE WATER OR ICE  PARTICLES HAVING RADII SMALLER THAN   MM  CM  &OR WAVELENGTHS OF INCIDENT  RADIATION WELL IN EXCESS OF  CM  THE ATTENUATION DEPENDS PRIMARILY ON THE LIQUID 
 /,1 Ê"  1*  9 )N THE (& BAND  THE AVERAGE NOISE POWER SPECTRAL DENSITY AT MID 
 For this reason,  receiver calibration must be performed over  a range of input levels, and the nonlineari - ties must be compensated for in the data processing. CW scatterometers depend on antenna beams to discriminate different angles of  incidence and different targets. Usually assumptions are made that the antenna pat - tern has constant gain within the actual 3 dB points and zero gain outside, but this  clearly is not an accurate description. 
    
 These aircraft undertake long-range maritime patrol duties that typicallyinclude anti-surface warfare (ASuW), anti-submarine warfare (ASW) and search and rescue (SAR). They carry a wide variety of sensors, communications equipment and weapons. In most cases a prime sensor is the airborne maritime surveillanceradar, intended to detect small targets on the sea surface in high sea states and to monitor surface vessels at long ranges. 
 SPEED CONVERTERS IS OFTEN SUCH THAT THE NOISE OF THE  !$ CONVERTER IS SIGNIFICANTLY GREATER  THAN THE THEORETICAL QUANTIZATION NOISE )N ADDI 
 Packaging of MMIC components into the T/R module must take into  consideration30,31,32 multiple elements as they impact the electrical performance. Power Conditioning Considerations.  Pulsed transmit amplifiers can consume  very high dc currents and special design attention must be paid to parasitic induc - tance that can generate very high voltage spikes and cause damage to MMIC power  amplifiers. 
 63. A. Farina, “Tracking function in bistatic and multistatic radar systems,” IEE Proc ., 133(7),   pt. 
 Moroney: Microwave Mixer and Detector Diodes, Proc. IEEE, vol. 59, pp. 
 4,l/Tisalso themaximum rate at~rhich information can bereceived. When frequency modulation isused, thevariation ofawith udepends ontheform ofmodulation just asitdepends, intheamplitude-modulation case, onthe pulse shape. Usually the frequency isvaried either (a) sinusoidally or(b)inasawtooth manner. 
 8.4). Thus it will be more limited in  hand width than most array feeds. The center-red feed of Fig. 
 25 28. 1977. IEE (London) Conf. 
 154.Nelson, E.A.:Quantization Sidelobes ofaPhasedArraywithaTriangular Element Arrangement, IEEETrans.,vol.AP-17,pp.363-365, May,1969. 155.Garver, R.V.:"Microwave DiodeControl Devices," ArtechHouse,Inc.,1976. 156.Whicker, L.R.,andR.R.Jones:ADigitalCurrent Controlled Latching FerritePhaseShifter,IEEE 1965International COnl,ention Record,pt.V,pp.217-223. 
 The characteristic of a  saturated amplifier is that, above a certain level,_the RF opt put is independent of the RF input.  A saturated amplifier is compatible with frequency and phase-modulated pulse compression  waveforms.  When used in an amplifier chain, the CF A is generally found in only the one or two  highest-power stages. 
 19. R. J. 
 15, pp. 31--36, October,  1972.  26. 
 The input to these detectors can be linear  video, square-law video, or log video. Because linear video is probably the most com - monly used, the advantages and disadvantages of the various detectors will be stated  for this video. Moving Window . 
 The delayed pulse ismixed with thecoding forthebasic pulse onthecommon cathode resistor Rand sent tothe master mixer. Itisnot necessary to code the azimuth pulse since itsfunction ismerely totransmit the sinusoidal frequency; any interference strong enough tomask this pulse would render thewhole system useless inany case. Atthereceiving station thebasic pulse isdecoded bythecoincidence circuit ofFig. 
 BASED APPLICATION IS THE .AVYS #OMPOSABLE &ORCE.ET  AN APPLICATION SIMILAR IN NATURE TO THE '##3 
  LOOKS TO THE RIGHT SIDE OF THE ORBIT PLANE  WHICH GIVES IT ACCESS TO THE #ANADIAN !RCTIC UP TO THE .ORTH 0OLE 4WICE DURING ITS MISSION  THE SPACECRAFT WAS YAWED  n FOR SEVERAL WEEKS  WHICH ENABLED  FULL COVERAGE OF !NTARCTICA 4HE RESULTING DATA WERE MERGED TO YIELD THE FIRST HIGH 
 Thus the  sea in the North Atlantic is not that much different from the sea in the South Pacific if the wind  conditions are the same, Land clutter, on the other hand, is highly dependent on the nature of  the terrain and the local conditions. Urban areas, cultivated fields, forests, mountains, desert,  and tundra all can produce different radar echoes. Furthermore, radar scattering from land is  affected by rain, snow cover, the type of vegetation or crops, the time of year, the presence of  streams and lakes, and man-made objects interspersed among the terrain. 
 Hoover, and J. W. Bredow, “High-performance, inexpensive polarimetric  radar for in situ measurements,” Proc. 
 CAL COORDINATES   IONOSPHERIC MODE STRUCTURE INTERPRETATION  AND ASSOCIATION OF MUL 
 51. J. W. 
 A true (logarithmic characteristic cannot be maintained down to zero input since  r.,01 --oo as 1';11 -0. At some point the receiver characteristic must deviate from logarithmic  and go through the origin. The practical logarithmic receiver will have a law given by  1·001 = a log ( l + ht';0). 
 Radar System Engineering  Chapter 12 – Selected Radar Applications  157     13.3.11  Literature   [Cur] N.C. Currie, C.E. Brown (eds), Principles and application of millimeter -wave  Radar, Aertech House, Norwood, MA,1987   [GM]  --”Cars Detroit Never Built ” (anitquarisch), Stirling Publishing Co. 
 SEC. 13.3] SELECTION OF THE CATHODE-RAY TUBE 485 because ofthe greater power required for deflection. These diiTerences areofsignificance only inairbmne equipment. 
 It is also  sometimes known as afeedforwardfilter, a nonrecursioefilter, afinite memoryfilter or a tapped  delay-linefilter. The weights wf for a three-pulse canceler utilizing two delay lines arranged as a  transversal filter are 1. -2, 1. 
 Proc. SPIE 2007 ,6568 , 656–802. ©2019 by the authors. 
 T. Taylor, “Design of line source antennas for narrow beamwidth and low sidelobes,” IEEE  Trans ., vol. AP-3, pp. 
 Any or all of these might contribute to the scattering of electromagnetic waves responsible for sea clutter. The basic ocean- . ographic descriptor of the sea surface, however, is the wave spectrum, which, while saying little about these features, contains a great deal of information about the sea surface in general and is central to the application of the Bragg scattering hypothesis. 
 NOISE 
 ELEMENT SPACING IS SMALL ENOUGH TO SUPPRESS GRATING LOBES -ONOPULSE  DIFFERENCE PATTERNS MAY BE APPROXIMATED IN THE SAME WAY FROM THE &OURIER TRANSFORMS OF THE CORRESPONDING CONTINUOUS ODD APERTURE DISTRIBUTIONS %LEMENT &ACTOR AND 'AIN OF 0LANAR !RRAYS  4HE MAXIMUM GAIN OF A UNIFORMLY  ILLUMINATED AND LOSSLESS APERTURE OF AREA  !  WITH A BROADSIDE BEAM  IS  '! MAX PL  . £Î°£{  2!$!2 (!.$"//+  7ITH A NONUNIFORM APERTURE DISTRIBUTION AND WITH LOSSES PRESENT  THE GAIN IS REDUCED  BY THE EFFICIENCY TERM G  TO   '! MAX PLH    )F THE APERTURE IS CONSIDERED AS A MATCHED RECEIVER  THEN THE AMOUNT OF ENERGY ARRIV 
 R. Griffiths: Video Integration in Radar and Sonar Systems, J. Brit. 
 Severe Storm Warning. One of the primary purposes of weather radars is to provide timely warnings of severe weather phenomena such as tornadoes, damaging winds, and flash floods. Long-term forecasting of the precise location and level of severity of these phenomena, through numerical weather prediction techniques, is beyond the state of the art. 
 Appl. Meteorol ., vol. 5, pp. 
 and L. R. Lavallee: Solid-State Transmitters, Electronic Progress, vol. 
 At high altitirde, there is little water vapor, and changes in ttrnperalLire liirvc 11ie most  effect on the refractive index.  Reflections from clear-air tirrbulence are thus a potential source of radar angel echoes.  Turbulent motion is characterized by a variable velocity field and tllc prshcncc of no~iun~for-  mities, or eddies, that produce mixing. 
 The energy into the coupler contains both difference signals coupled as the cosine and sine of the angular position of the coupler, o^f, where W5 is the angular rate of rotation. The hybrid adds the combined difference signals A to the sum signal 2. The 2 + A and 2 - A outputs each look like the output of a conical-scan tracker except that the modulation function differs by 180°. 
 GATION HAS BEEN USED TO ARGUE THAT A FULLY POLARIMETRIC TREATMENT IS UNNECESSARY  SO IT IS COMMON PRACTICE TO REPRESENT THE SCATTERING BEHAVIOR IN TERMS OF SCALAR RADAR CROSS SECTION 2#3  &ULLY POLARIMETRIC FORMULATIONS ARE RELEVANT WHEN MODELING COMPLEX SCATTERING PROCESSES   AND FOR TARGET CLASSIFICATION STUDIES )N GENERAL  AIRCRAFT AND SHIPS HAVE DIMENSIONS THAT PUT THEM WITHIN THE RESONANT  SCATTERING REGIME  THOUGH THE SMALLEST AIRCRAFT AND CRUISE MISSILES WILL LIE IN THE 2AYLEIGH SCATTERING REGIME FOR THE LOWER HALF OF THE (& BAND (ERE  THE 2#3 DISPLAYS LIMITED ASPECT SENSITIVITY AND A STRONG DEPENDENCE ON THE TARGETS GROSS DIMENSIONS &OR AN AIRCRAFT  THE SPAN OF THE WINGS  THE FUSELAGE LENGTH  THE TAIL AND ELEVATOR SPAN  THE VERTICAL STABILIZER AND RUDDER HEIGHT  AND THEIR RELATIVE LOCATIONS ARE THE MAIN FEATURES THAT INFLUENCE THE 2#3 4ARGET SHAPING ON A SCALE SIZE MUCH LESS THAN A WAVELENGTH WILL HAVE LITTLE EFFECT !CCURATE MEASUREMENTS OF RADAR SCATTERING AT (& FREQUENCIES IS CHALLENGING  BUT FACILITIES FOR MAKING SCALE MODEL MEASUREMENTS ARE .   (& /6%2 
 OFF  JAMMER 3/*  CASE  THE JAMMING PLATFORM REMAINS CLOSE TO BUT OUTSIDE THE LETHAL RANGE OF ENEMY WEAPON SYSTEMS AND JAMS THESE SYSTEMS TO PROTECT THE ATTACKING VEHICLES 3TAND 
 COMBINED SPACE 
 Direct-solution methods, on the other hand, do  not suffer from problems of slow convergence but, in general, require components of such  high accuracy and wide dynamic range that they can only be realized by digital means. Of  course, closed-loop methods can also be implemented by using digital circuitry; in which  case, the constraints on numerical accuracy are greatly relaxed, and the total number of  arithmetic operations is much reduced by comparison with direct-solution methods. The  majority of implementations has become open loop with digital technology. 
 (21.33), (21.36), (21.37) are of the form sin NzI'sin z (21.38) with z = 2<nx'vTI\RQ (21.39) for the azimuth resolution case, and sinzlz (21.40) with z = cn[2Rlc - 2R1Ic] (21.41) for the range resolution case. If the value L = (N + I)VT (21.42) is combined with Eq. (21.39) and one recognizes that OLT = 2TfB (21.43) where B is the chirp signal bandwidth, one can show that the azimuth resolution 8a and the range resolution 8r are given by 8fl = (1.4XK0V(IrL) (21.44) . 
 In Figure 8.1 the various transmission types in the time and frequency domain are represented.   Figure 8.1a shows a simple CW Radar instrument in the time and frequency domain.  A  moved target shifts the line in the frequency domain for the receiving signal of  € f0 to  € f0+fd. 
 TechnoL, vol. 18, p. 60, February 1988. 
 Guided missiles can be characterized in several ways, 1^ based on their mis- sion, type of guidance, sensing wavelength, source of guidance energy, etc. The discussion here will narrow down to the particular radar homing types which form the vast majority of operational systems. Based on their use, missile systems can be categorized as surface-to-surface, air-to-surface, surface-to-air, and air-to-air. 
 NORMAL  R    D"   INTERFERENCE .    0FA    
 AP-20, pp. 2–10, January 1972.  81. 
 Heater hum modulation must beminimized by keeping thed-cand r-fimpedance between cathode and ground assmali aspossible. The oscillator tube must beofanonmicrophonic type. The circuit asawhole must berigidly constructed and shock-mounted, Power-supply ripple must not exceed afew millivolts. 
 In this approach, the returns in the delta and sum channels are coherently cross-correlated pulse to pulse, and then the real part of the cross-correlation sum is normalized by a term determined by noncoherent integration in the sum channel to form the measured monopulse ra- tio. The same noncoherent sum used to normalize the measured monopulse ratio may be also used in the target decision logic for detection thresholding. The rmse for multiple-pulse coherent monopulse differs from that of a single- pulse monopulse only by the square root of the number of pulses in the denom- inator. 
 D. Turley, “Robust adaptive beamforming for HF  surface wave over-the-horizon,” IEEE Trans ., vol. AES–40, no. 
 58. P. E. 
 Lynch, “Aperture synthesis for HF radio signals propagated via the F-layer of the ion - osphere,” Stanford Electron. Lab. Tech. 
 ILAR DESIGN CALLED THE  PARABOLIC TORUS  IS MORE APPLICABLE 4HE PARABOLIC TORUS REFLECTOR IS  A SURFACE THAT IS SPHERICAL IN ONE PLANE AZIMUTH OR ELEVATION  AND PARABOLIC IN THE OTHER PLANE 4HIS DESIGN TAKES ADVANTAGE OF BOTH THE WIDE SCANNING ENABLED BY THE SPHERICAL SHAPING AND THE HIGH APERTURE EFFICIENCY ENABLED BY THE PARABOLIC SHAPING 4HE HEIGHT ELEVATION  DIMENSION OF THE REFLECTOR IS SET BY THE REQUIRED ELEVATION BEAMWIDTH 4HE PARABOLIC TORUS HAS SEEN APPLICATION IN VARIOUS RADARS INCLUDING THE ORIGINAL  "-%73 SYSTEM  AND THE 303 
 ING TRANSMISSION  WHEREAS OTHERS OPERATE IN THE RECEPTION PHASE !DDITIONALLY  SOME ARE ACTIVE AGAINST MAIN 
 TED  BUT THE VARIATION WILL AMOUNT TO LESS THAN  D" FOR MOST WAVEFORMS 2OTHENBERG AND 3CHWARTZMAN  PROVIDE DETAILS AND ALSO TREAT THE PROBLEM AS A MATCHED FILTER 4HE PRECEDING DISCUSSION ASSUMES AN EQUAL 
 • The increased range resolution and doppler resolution in synthetic aperture radars (SAR) for the imaging of a scene, the use of inverse SAR (ISAR) for the imaging of targets, and the replacement of optical processing with digital processing for SAR imaging. • The adaptive antenna for application in sidelobe cancelers (as an ECCM) and AMTI radar. • The use of computers to reliably and quickly predict the capability and coverage of radar systems in the real environment. 
 Another interesting feature of surface-based ducts is the skip zone near the normal  horizon, in which the duct has no influence. It should be noted that the surface duct cre - ated from a surface-based trapping layer does not have this skip zone phenomenon. Height-finding radars usually determine height from energy path assumptions  within a normal environment. 
 Regulation becomes poorer with changing load. Booster Armature Voltage Regulation.-A recent development to improve dynamotor regulation isthe construction inthe dynamotor. SEC. 
 When the radar wavelength is large compared with the circumference of a scattering  particle or diameter D (Rayleigh scattering region), the radar cross section is  (13.17)  where I K j2 = (£ -I)/(£ + 2), and l = dielectric constant of the scattering particles. The value  of I K 12 for water varies with temperature and wavelength. At l0°C and 10 cm wavelength, it is . 
 A fascinating memoir of the work on the ASV installation is given by John Clements [ 4] (he was then an RAF wireless electrical mechanic with 32 Maintenance Unit (32 MU); he retired doi:10.1088/978-1-6432-7066-1ch2 2-1 ªMorgan & Claypool Publishers 2018. from the RAF in 1976 as an Air Commodore) . In addition to developing the radar installation, development work includ ed test equipment and generators for running the equipment on the ground. 
 This bandwidth isthen determined simply bythe wavelength and therange oftarget velocities. If,however, weconsider only targets ofone radial velocity, oruse some more complex indicator that divides the possible doppler range. 136 C-WRADAR SYSTEMS [SEC. 
 VALUED  RANGE 
 73-82, Oct. 28-31, 1974, IEEE Catalog no. 74 CHO 934-0  NEREM. 
 The feed size determines the  edge taper, i.e., the larger the feed, the greater the edge taper. The plot in Figure 12.4  shows how the three loss terms, and the total loss, vary as a function of feed pattern  edge taper, that is, the feed power directed at the edge of the reflector, relative to the  feed pattern peak. This is used here because the feed pattern is measured independent  of the reflector. 
 Usually there are four basic aspects to automatic detection: (I) the inte9ration of the  pulses received from the target; (2) the detection decision; and the determination of the target  location in (3) range and (4) azimuth. Sometimes there is also included in automatic-detection  circuitry the means for maintaining a constant false alarm rate (CFAR ). This is discussed  separately in the next section. 
 This phenomenon must be viewed in the context of the closed antenna tracking loop. Since for a constant LOS rate the residual boresight error is a constant, any radome error which tends to increase the apparent boresight er- ror constitutes regenerative feedback. A radome error which makes the boresight error smaller is degenerative. 
 Thevoltagewaveform ofthereceived signalismodulated bythesquareoftheantenna electric-field-strength-pattern, whichisequaltothe(one-way) antenna powerpatternG(O), described bythegaussian function as (2.776(2)G(8)=Goexp-Or (4.29) (4.30)Sincetheantenna isscanning atarateofb.deg/sthetimewaveform maybefoundfrom Eq.(4.29)bydividing boththenumerator anddenominator oftheexponent byb•.Letting 81{)s=t,thetimevariable, andnotingthat8Blbs=to,thetimeontarget,themodulation of thereceived signalduetotheantenna patternis ()k(2.776(2 ) Sa1=exp- 2to. where k = constant. The angular frequency spectrum of this time waveform is found by taking  its Fourier transform. 
 13.18 Effect of ducting on low-angle clutter; wind speed about 10 kn.INCREASE IN MEDIAN BACKSCATTER (dB) DUCTING NONDUCTING . Shadowing. The possibility of shadowing must be seriously considered when- ever the sea is viewed at grazing angles smaller than the rms slope angle of the sea surface. 
   05,3% #/-02%33)/. 2!$!2   n°££ IN AN UP 
 NAVIGATION RAD ARS v )45 
 The optlmum number 1r1 (or the sccond thrcstiold) will dcpentl on lhc  nature of the pdf. When the optimum m is used with non-Rayleigli-clutter, the tn-out-of-tr  detector seems to be better than the other receiver criteria.'".28  The logarithmic receiver has an output voltage whose amplit~rdc is proportional lo tlie  logarithm of the input envelope. A logarithmic characteristic provides a constant false alarm  rate (CFAR) when the input clutter or noise has a Rayleigh pdf. 
 WAVE 
 In-band spurious noise: This is the factor noted in Table 4.1, since it is most serious to system operation and usually cannot be filtered out. In-band spu- rious noise may interfere with other systems or may prevent achieving desired MTI cancellation or pulse compression sidelobe levels in the tube's own system. In-band spurious noise also sets a limit on the spectrum improvement that may be obtained by pulse shaping (Sec. 
 SCREENING  STANDOFF  AND ESCORT JAMMERS 4HESE CALCULATIONS APPLY TO BOTH SEARCH AND TRACKING RADARS &OR TRACKING RADARS  IT IS ALSO WORTHWHILE TO CONSIDER THE DEGRADATION OF MEA 
 vii. sensors Editorial Special Issue “Synthetic Aperture Radar (SAR) T echniques and Applications” Fabio Bovenga Institute for Electromagnetic Sensing of the Environment (IREA), Italian National Research Council, Via Amendola, 122/d, 70126 Bari, Italy; bovenga.f@irea.cnr.it Received: 24 March 2020; Accepted: 25 March 2020; Published: 27 March 2020/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: This editorial of the special issue titled “Synthetic Aperture Radar (SAR) Techniques and Applications”, reviews the nineteen papers selected for publication. The proposed studies investigate diﬀerent aspects of SAR processing including signal modelling, simulation, image analysis, as well as some examples of applications. 
 VELOCITY AMBIGUITIES IN WEATHER RADARS v  * !TMOS /CEAN 4ECHNOL  VOL     PP n    * # (UBBERT  ' -EYMARIS  AND 2 * +EELER  h2ANGE 
 x°È  2!$!2 (!.$"//+  ON A SINGLE CHIP OR ON SEPARATE CHIPS DEPENDING ON YIELD  COMPLEXITY  SPEED  CACHE  SIZE  AND SO ON %ACH PROCESSOR ARRAY MAY  CONSIST OF PROGRAMMABLE SIGNAL PROCESSORS  030   GENERAL PURPOSE PROCESSORS '00   BULK MEMORY "-   INPUT 
 The ability to steer the beam electronically can be used to  stabilize the beam direction when the radar is on a platform, such as a ship or aircraft,  that is subject to roll. pitch, or yaw.  The above attributes of an array antenna offer the radar systems engineer additional  flexibility in attempting to meet the requirements of radar applications. 
 SURVEILLANCE RADARS PROVIDE AN OFF 
 L. Zverev, “Digital MTI radar filters,” IEEE Trans.,  vol. AU-16, pp. 
 S.. and J. S. 
  
 DIAMETER DISH AND A SPECIFIED TRACKING PRECISION OF  MRAD RMS    B  !.-03 
 6.lti). Onthe sweeps corresponding tothe right-hand position the origin issimultaneously shifted vertically byanamount proportional tothesine oftheelevation angle. Any single echo therefore appears intwo neighboring positions, and the slope ofthe line joining the two “dots” isarough measure of elevation angle which isaccurate totwo orthree degrees under theusual circumstances ofuse. 
 Mitnik et al., “Structure and dynamics of the Sea of Okhotsk marginal ice zone from ‘ocean’  satellite radar sensing data,” J. Geophys. Res ., vol. 
 Proc. Sys. (IIPS) , AMS, Orlando, 2002. 
 314-318. 1966.  127. 
 The detection of signals in the presence of  clutter is discussed in Chap. 13.  A network wllose frequency-respoose function maximizes the output peak-signal-to-tnean-  noise (power) ratio is called a matchedfilter. 
 Ground-plane range resolution is coarser than slant-plane range resolu - tion. ( Courtesy of SciTech Publishing, Inc .) FIGURE 17.6  Minimum PRF for SAR: The apparent line-of-sight velocity of point A  is toward the radar, whereas the apparent line-of-sight velocity of point B is away from  the radar. These determine the minimum PRF of 2 V/D, where V = platform speed and D =  antenna physical diameter. 
 A note of caution is in order when considering pulse compression for meteo- rological radars. This relates to the matter of range sidelobes. Careful design is necessary to minimize these sidelobes, just as antenna sidelobes should be min- imized, in order to mitigate the effects of interpretive errors caused by wide- dynamic-range distributed weather targets. 
 TION IS WELL PREDICTED BY THE STRAIGHT 
 Appl. Meteorol ., vol. 13, pp. 
 The reflection from the building  occurs in exactly the same amount of time, but the reflection from the moving aircraft  occurs in less time because the aircraft has moved closer to the radar in the interval  between transmitted pulses. The precise time that it takes the reflected signal to reach  the radar is not of fundamental importance. What is significant is whether the time  changes between pulses. 
 Results The proposed algorithm was compared against three change detection methods: PCAKM [ 13], GaborTLC [ 18], and NR-ELM [ 10]. All three methods are implemented with their default parameters by using the publicly available code provided by the authors. The ﬁrst dataset consisted of 1024 ×1024 regions from an SAR image pair provided by Lockheed Martin (Bethesda, MD, USA). 
 The complete SAR–SS consists of two essential steps: the phase screen simulator and propagation simulator which corresponds to the wave propagation history. When the radio wave penetrates through the ionosphere, the scintillation phase is introduced into the signal by the phase screen simulator. The 2-D scintillation phase screen is generated by multiplying the irregularity’s phase spectrum by complex white noise with unit power. 
 6G COS @   WHERE 6G IS THE GROUND SPEED OF THE PLATFORM AND  A IS THE ANGLE SUBTENDED BETWEEN THE LINE 
 The sharply rising leading edge of the waveform is  the basis for the precise height estimation. The half- The authors are members of the Space Department , The Johns Hop­ kins University Applied Physics Laborator y, Laurel, MD 20707.  176 Antenna  pattern  decay  -27 -7 0 7 27 37 47  t =7} Time  27 Illuminated area at 37  47  Figure 1-Pulse-limited geometry (SWH is the significant wave  height). 
 4.9b is an example of a trar~soersal  filter. Its general form with N pulses and N - 1 delay lines is shown in Fig. 4.1 1. 
 7AVE 0OWER %LECTRONICS  .EW 9ORK )%%%  0RESS AND 7ILLEY )NTERSCIENCE    P    ! 3 'ILMOUR  *R   0RINCIPLES OF 4RAVELING 7AVE 4UBES   "OSTON  -! !RTECH (OUSE    3EC    2 3 3YMONS  h4UBES 3TILL VITAL AFTER ALL THESES YEARS v  )%%% 3PECTRUM  VOL   PP n   !PRIL    2 - 0HILLIPS AND $ 7 3PREHN  h(IGH 
 It is then suppressed, travels  . r06 HOW RADAR WORKS  back to the bottom line, and starts a fresh painting of ar  upward line simultaneously with the next outgoing  transmitted pulse. This line is not over the preceding  one, but is displaced slightly to the right; indeed, the  successive sweeps are spaced out over the square to  correspond with the azimuthal direction in which the  aerial is sweeping. 
 converter hold  Sample A/0 and converter hold  0, or quadrature, channel Digital Sub- store tractor  Magnitude  {/2 + 02,112  Digital Sub- s lore I roe tor  Figure 4.21 Block diagram of a simple digital MTI signal processor. 0/A To  converter display . 120 INTRODUCTION TO RADAR SYSTEMS  words are stored in a digital memory for one pulse repetition period and are then suhtracred  from the digital words of the next sweep. 
 MENT EG  CONTAINING LAND  SEA  AND RAIN  WILL CAUSE AN EXORBITANT NUMBER OF FALSE ALARMS FOR A FIXED 
 OUS IMAGE ALONG TRACK -ISMATCHES APPEAR AS hSCALLOPINGvSYSTEMATIC BRIGHTNESS MODULATIONS AT BOUNDARIES BETWEEN EACH OF THE FRAMELETS 3CAN3!2 n )F SWATH WIDTH IS THE DRIVING REQUIREMENT  THEN AZIMUTH RESOLUTION  CAN BE TRADED FOR RANGE COVERAGE 4HE TRICK IS TO MULTIPLEX SEVERAL BURST 
 Schonland, 8. F. J.: "The Flight of Thunderbolts," 2d ed., Oxford, Clarendon Press, London. 
 Therefore, it is deﬁnitely essential to study the high cross-range resolution further for airborne or spaceborne WAS radar in short dwell time situations. Sensors 2019 ,19, 1920; doi:10.3390 /s19081920 www.mdpi.com /journal/sensors 69. Sensors 2019 ,19, 1920 Several researchers have studied this issue of WAS imaging in previous works, Scan-synthetic aperture radar (Scan-SAR) [ 1,12,13] can acquire a wide-region compared with conventional TOPs SAR mode [ 14,15], strip SAR mode [ 16–18] and spotlight SAR mode [ 19], and it is an eﬀective means for WAS imaging. 
 BIT  D"  FOR EVERY DOUBLING OF THE SAMPLE  RATE /VER 
 —Here also, when the repetition rate ishigh enough, therelative spacing ofpairs ofreply pulses orthewidth ofpulses canbevaried atvoice frequency togive telephonic communication, usable when theinterrogate or-responsor points steadily atthebeacon. STATISTICAL CONSIDERATIONS 8.9. Tra5c Capacity .-For every beacon there issome limit tothe total amount ofenergy itcan radiate per second, with acorresponding limitation ofthe number ofitsreplies per second and ofthenumber of interrogators that can work with itsimultaneously. 
 S.: Mechanical and Electrical Tolerances for Two-dimensional Scanning Antenna Arrays.  IRE Trans., vol. AP-6.'pp. 
 By  means of a special maximum -minimum process a clu tter-representative sum -value Sr, will be  selected from the “A” sum -values S1 to SA. The threshold value is then calculated using a mu l- tiplicative ( α/L) and/or additive ( β/L) factor.  A number of possibilit ies are possible for implementing the maximum -minimum pro cess. 
 FIELD AMPLIFIER  LIKE THE MAGNETRON  IS A CROSSED 
 13.3. 30. L. 
 The synchronization signals would automatically beseparated from the video signals. The use of100 per cent of the time and the freedom from restrictions imposed by the radar PRF would lessen the sensitivity tointerference and permit much more flexibility than isavailable with the time-sharing technique.. 712 RADAR RELAY [SEC. 
    !#    %$"     %.   -4) 2!$!2  Ó°x DESCRIBED HERE  IS ITS REDUCED MISMATCH LOSS &OR THE  FILTERS IN THE ABOVE DESIGN   THE AVERAGE MISMATCH LOSS IS  ,M  D"  A SAVINGS OF  D" AS COMPARED TO THE  ALTERNATIVE OF A  D" WEIGHTED $OLPH 
 Use of this technique in millimeter-wave seekers against surface targets provides a terminal mode with significantly lower glint than the active or the semiactive radar mode. Other System Configurations. Variations of the above seeker types as well as multimode combinations have been studied and in some cases implemented to take advantage of new and emerging technologies. 
 -  Ê",Ê/ 
 Queen: Modified Generalized Sign Test Processor for 2-D  Radar, IEEE Trans., vol. AES-IO, pp. 574-582, September, 1974. 
 ££   XXY4N 4 4 
 Barton, D. K.: "The Radar Equation," Artech House, Dedham, Mass., 1974.  57. 
 RELATION FUNCTION TO  S     §S  AN INCREASE OF A FACTOR OF TEN COMPARED TO THE RESULT  FOR A  
 N. A.: Frequency Scanning, chap. 2 of "Microwave Scanning Antennas. 
 Because it is only ~100 km above the Earth’s surface, the maximum  range that can be reached via one-hop E-layer propagation is only ~2000 km, though  normally the layer is not totally reflecting, so some energy continues upward to the  F-layer where it is reflected to reach the Earth’s surface at much greater ranges. F Region.  This is the highest-altitude region of interest for skywave propagation,  and it is also the region of greatest electron density. 
 Instead of  selecting only the largest signal for processing, the indicated position of the target at each  frequency can be weighted according to the amplitude of the return.40 Only a small number of  frequencies is needed to reduce substantially the glint error. The reduction in rms tracking  error by processing only that signal (frequency) with the largest amplitude is appro~irnately~~  wticrc rr, is the sitigle-ftequeticy glint error and N is tlle number of frequencies. The tracking  error will not decrease significantly for more than four pulses. 
 SELVES BY THE INCIDENT WAVE AND THEN SOLVES A SYSTEM OF LINEAR EQUATIONS 4HESE SURFACE FIELDS BECOME UNKNOWNS TO BE DETERMINED 4HE TWO EQUATIONS ARE COUPLED BECAUSE THE UNKNOWNS APPEAR ON BOTH SIDES OF BOTH EQUATIONS 4HE METHOD OF SOLUTION IS KNOWN AS THE METHOD OF MOMENTS -/-    WHICH REDUCES THE INTEGRAL EQUATIONS TO A COLLECTION  OF HOMOGENEOUS LINEAR EQUATIONS THAT MAY BE SOLVED BY MATRIX TECHNIQUES /NCE THE BOUNDARY CONDITIONS HAVE BEEN SPECIFIED  THE SURFACE  3 IS SPLIT INTO A COL 
 F. E. Nathanson and J. 
 (14) Identification of Friend or Foe radar  system used in military aircraft. (15) Attack-warning radar  system used in military aircraft to give warning of aerial  attack. (16) ‘Mountain Goat’ radio beacon to warn navi-  gators of high ground, cliffs, and mountam-peaks. 
 13. R. S. 
 ARRAYS  AND   ! NUMERICAL EXAMPLE IS REPORTED IN &ARINA ET AL  WITH AN 5,! OF  .    ELEMENTS  AND -    SUB 
 I'r.oc.. IRE. vol. 
 OPMENT OF HIGH 
 38,   pp. 126–140, 2000. 128. 
 TO 
 193-195, July 1967. 66. Pavel'yev, A. 
 FORMING NETWORKS 4HE ENERGY IN THE ENERGY STORAGE DEVICE IS DISCHARGED BY A VERY CAPABLE SWITCH 4HE LINE 
 Synthetic aperture radar (SAR) . SAR is a coherent * imaging radar on a moving  vehicle that uses the phase information of the echo signal to obtain an image of a  scene with high resolution in both range and cross-range. High range resolution is  often obtained using pulse compression. 
 ,-Ê 
 7.3 Aperture distribution giving two beams. In most phased array systems only the phase can be controlled. Ignoring the required amplitude variations still leads to good approximations for forming mul- tiple beams, by superimposing the various required phase-shifter settings (modulo 2Tr). 
 TIVE FILTERING   #ROSS 
 ANGLE OPERATION  AND UNUSUAL ATMOSPHERIC RESEARCH INCLUDING WHAT HAVE BEEN CALLED hAIR SPIKESv.   4(% 2!$!2 42!.3-)44%2   £ä°£ 4HE ABOVE DISCUSSION WAS MAINLY ABOUT THE GYROTRON AMPLIFIER 4HE GYROTRON HAS  ALSO BEEN OPERATED AS AN OSCILLATOR TO PRODUCE VERY HIGH POWER  BUT THE OSCILLATOR VER 
 TERIZE THE RELATIVE (6 PHASE OF THE TRANSMITTED FIELD  AS WELL AS THAT OF THE RECEIVERS.   30!#% 
 Phase Unwrapping Both minimum cost ﬂow (MCF) network and Delaunay 3D are employed for phase unwrapping, and a coherence threshold of 0.35 is chosen [ 35]. Then, 39 interferometric pairs with poor unwrapping and low coherence are eliminated. 3.3. 
 When the clutter-doppler-frequency compensation cannot be obtained  100  90  m  "O  ...  !? u 2  c  Q)  E  Q)  > 0 a E  10  0  0001 001 0·1  Uclfp  Figure 4.34 Effect of a nonzero clutter doppler frequency on the improvement factor of a three-pulse  canceler. fr= mean frequency of the clutter spectrum, u, = standard deviation of clutter spectrum,  fP = pulse repetition frequency. 
 Conv.Record,vol.8,pt.4,pp.116-124, 1960. 91.Thisexpression wassuggested byWarrenD.White,oneofthereviewers oftherevisedmanuscript of thisbook.. CHAPTER  ELEVEN  EXTRACTION OF INFORMATION  AND WAVEFORM DESIGN  11.1 INTRODUCTION  In Chap. 
 TO 
 R. M. Wakimoto and R. 
 STATE TRANSMITTERS  AND THERE MIGHT BE LITTLE GAINED BY DOING SO 4HE GRID 
 As will be  seen, this average is about 2 to 3 dB smaller than the upwind returns. Moreover, the  early  NRL 4FR data was used liberally in the older data summaries, and it was noted  above that there is a difference of 3 to 4 dB between the early and later presentations  of the same NRL 4FR data, the latter  being used in Figure 15.3 a and b. With these  corrections, the curves might show closer agreement. 
 RECEIVERS, DlSPLA YS,ANDDUPLEXERS 367 24.Watson, H.A.,"Microwave Semiconductor Devices andTheirCircuitApplications," McGraw-Hili BookCompany, NewYork,1969. 25.Howes.M.J.,andD.V.Morgan (eds.):"Microwave Devices," JohnWiley&Sons,NewYork,1976. 26.Herg,A.A.:RadarIndicators andDisplays, chap.6of"RadarHandbook," edtbyM.I.Skolnik, McGraw-Hili BookCompany. 
 Another useful modification is to separate the beams at zero elevation so that the data from  the vertical and the slant beam do not appear close in time.  542INTRODUCTION TORADAR SYSTEMS scansitshorizontal fanbeaminelevation tomakeanelevation anglemeasurement ofthe targetfoundattherangedesignated bytheair-surveillance radar.Thenodding-beam height finderscansitsbeaminelevation bymechanically rockingtheentireantenna. Itispossible to mechanically slewanodding-beam heightfinderafull180°inarelatively shorttime(within twoseconds, forexample). 
 The handling of a large  number of short-range targets in track can drive the processor to full utilization and require  that search operatiofis, which have lower priority than track, be reduced. Thus the mechanism  by which the system saturates depends on the nature of the target situation.  TI/I'FUTTRONICAI.I.Y STF.F.RFD PI/ASH) ARRAY ANTFNNA INRADAR327 Table8.2Example ofpriorities foratacticalsystem 121 Previously scheduled events lhatcaptureradarfor longperiodsoflimeDedicalcd mode Burnthrough Targetdefinilion Speciallest Engagcll1cnts Engagedhostilc Ownmissile Preengagedhostile 2Time-crilical High-priorily transition High-priority confirmal ion Horizonsearcho SpecialreqIIl'st BlIrtllhrollgh Targeldefinition Specialscans TargelaCljllisition 4High-priority tracks ConfirmedhostiIe Assumed hostile Unevaluated Controlled friendly Confirmation Tracktransition 5Low-priority lrack Assumed friendly Confirmed friendly Above-horizon search AIIcoverages Specialtest 7Simulation. 
 To see how the multi-  vib operates we must first ‘catch’ it at a quiescent state.  FIG. I2  At any such instant picture the anode current in one  valve increasing. 
 The Fourier transform permits the aperture distribution A (z) to be found for a given  field-intensity pattern E(</> ), since  (7.14)  This may be used as a basis for synthesizing an antenna pattern, that is, finding the aperture  distribution A(z) which yields a dec;ired antenna pattern E(q,).  In the remainder of this section, the antenna radiation pattern will be examined for  various aperture distributions using Eq. (7.10). 
 20. Bean. B. 
 DOPPLER CONTOURS 4HE RADAR OPERATED AT  '(Z  RADIATING A PEAK POWER OF  7 AT  DUTY FACTOR FROM A TRAVELING WAVE TUBE AMPLIFIER 474!  4HE WAVEFORM WAS MODULATED #7 4HE RECEIVER FRONT END WAS A TUNNEL DIODE AMPLIFIER  WHICH MAINTAINED THE NOISE FIGURE TO BE LESS THAN  D" AT ALL OPERATING TEMPERATURES -EAN INPUT POWER WAS  7 DC THE INSTRUMENT MASS WAS  KG 4!",%  3CATTEROMETERS .AME 3PACECRAFT #OUNTRY 9EAR !NTENNA "AND 0OLARIZATION 2AD3CAT 3KYLAB 53!    0ENCIL BEAM +U 66  (( 3!33 3EASAT 53!  &ANBEAMS +U 66  ((%3#!4 %23 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.44  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 The capsule’s trajectory was estimated by doppler radio readings and aerodynamic  calculations, and by subtracting this from the absolute radar altitude readings, a  ground profile could be measured. 
 7, Artech House, Norwood, Mass., 1978, sec. IV-Il, pp. 299-301. 
 On the  other hand, crowbars are not usually needed with line-type modulators, which store  less energy in their pulse-forming network. Certain crossed-field amplifiers can be pulsed by means of a control electrode,  located in the tube’s drift region, without a separate full-power pulse modulator.49  This is called dc operation . Even though dc operation avoids a high power modula - tor, it has seldom been used because it requires a much larger capacitor bank to limit  droop, an arc in the tube requires a crowbar that interrupts operation for a few seconds  instead of only for a single pulse, and the adjacent radars might inject enough RF  power into the radar antenna and back to the transmitter to turn on a dc operated CFA  at the wrong times. 
   AS DESCRIBED IN 3ECTION  )N THIS PREDICTION  3.2 IN DECIBELS IS PLOTTED AS A FUNCTION OF OPERATING FREQUENCY AND GREAT 
 F. C., Jr.: Steerable Array Radars, IRE Trans., vol. MIL-5. 
 Theamount ofisolation required depends onthetransmitter powerandtheaccompany­ ingtransmittcr noiseaswellastheruggedness andthesensitivity ofthereceiver. Forexample, ifthesafevalueofpowerwhichmightbeapplied toareceiver were10mWandifthe transmitter powerwereIkW,theisolation between transmitter andreceiver mustbeatleast 50dB. Theamount ofisolation neededinalong-range CWradarismoreoftendetermined by. 
 Equation (10.19)canbewrittenas 1 ( S(f))*. H(J)=----- x G-- exp(-]2nJt)Nj(f) aNj(f) 1(10.20) Thisindicates thattheNWNmatched filtercanbeconsidered asthecascadeoftwofilters.The firstfilter,withfrequency-response functionIjNj(J),actstomakethenoisespectrum uniform, orwhite,Itissometimes calledthewhitening filter.Thesecondisthematched filterdescribed byEq.(10.15)whentheinputiswhitenoiseandasignalwhosespectrum isS(J)jNj(J). 10.3CORRELATION DETECfIONl4-23 Equation (10.18)describes theoutputofthematched filterasthecrosscorrelation between the inputsignalandadelayed replicaofthetransmitted signal.Thisimpliesthatthematched-filter receiver canbereplaced byacross-correlation receiverthatperforms thesame mathematica~ operation, asshowninFig.10.3.Theinputsignaly(t)ismultiplied byadelayed replicaofthe transmitted f1gnals(r-1;),andtheproduct ispassedthrough alow-pass filtertoperform theintegration. 
  IS OUTWARDLY SIMILAR TO ITS PREDECESSOR 4HE  SOLAR PANELS ARE PARALLEL TO THE ALONG 
 9.2). A balanced mixer uses a hybrid junction, a  magic T, or an equivalent. These are four-port junctions. 
 A digital clutter map is generated which establishes the thresholds for the zero-velocity  cells. The map is implemented with one word for each of the 365,000 range-azimuth cells. The  original MTD stored the map on a magnetic disc memory. 
 vol. AI'S-l  pp. 486-,503, September. 
 An alternative digital receiver architecture is shown in  Figure 6.19 with the relevant signal spectra shown in Figure 6.20. The A/D converter  output signal x n( ) is processed using a Hilbert transformer comprising FIR filters  h1(n) and h2(n), where the frequency responses are given by   | ( )|| ( )| H H1 2 1 w w≈ ≈    | |w w− ≤0B (6.47) and  H j B j B1( ) ( ), | | , | |w H ww -w w w20 0+≈− ≤ ≤ (6.48) The filter outputs form the desired complex valued signal x n( ) centered at frequency  w0, while rejecting the image centered at −w0. The final stage is to perform a frequency  shift and sample rate reduction by decimating the signal by selecting every Dth sample. 
 moment that thk isso. Then (18) Now letasignal bereceived bythe antenna, and letSbethe available signal power—that is,thepower which would beabsorbed byamatched load (R=Z)atBC.Ingeneral, the mean-square signal voltage Z developed across Rwillbe 4R2Z ~=~@+z)” from which wehave(19) (20) From Eq. (20) weshould infer that the most favorable condition possible isattained bymaking Rinfinite, that is,byterminating the antenna line inanopen circuit. 
 voltage and valve characteristics.  The circuit is unstable. The ‘effect’ is out of all pro-  portion to the ‘cause,’ and, indeed, remains when the  ‘cause’ is removed. 
 D" )02 VALUE  L CPN !NOTHER CHOICE IS (ANN OR h(ANNINGv  WEIGHTING  WHICH RESULTS IN AN  EVEN WIDER MAIN BEAM OF   CPN THE FIRST SIDELOBE IS n D" BELOW THE PEAK   AND THE FAR SIDELOBES ARE VERY LOW COMPARED WITH UNIFORM OR 4AYLOR WEIGHTING !N EXCELLENT DISCUSSION OF OVER  WEIGHTING FUNCTIONS NOT INCLUDING 4AYLOR  IS GIVEN BY (ARRIS  3IGNAL 
 7.25  Thinned Arrays  ..................................................  7.26  Impedance Variation of Free Space  ...................  7.27  Element Impedanc e  ........................................... 
 Compara- tive PPI photographs taken simultaneously atthetwo stations areshown inFig. 17.21. The only difficulties ofconsequence involved occasional loss ofsynchronization, usually because ofpulse interference picked up onthe radio link oronthe radar set. 
 These interrogators were tobereplaced indue course with similar equipment operating atanew and higher region offrequency. Special separate antennas areobviously required. The contrary view, more widely held inthe United States, is that the provision ofsuitable beacons isbut asmall part ofthe over-all complication and expense ofintroducing radar inanew band offre- quency; that the frequencies used forradar sets forany given purpose tend togroup inasmall number ofreasonably narrow bands; that since the radar setitself can beasgood aninterrogator-responsor as onecould desire, itisputting complication inthewrong place toadd more equipment toacrowded airplane; and that the display ofthe beacon signals and the performance asawhole will beinferior when the beacon frequency isconsiderably below theradar frequency. 
 A negative voltage is thus applied to  the grid of the next valve (because of the greater volts-  drop across the anode resistance), and the effect of this  negative grid voltage is to drive the steady anode current  of the second valve down. This tends to make the grid  of the first valve more positive, and still further increases  the anode current of that valve. The effect is cumulative,  and after a predetermined time the cumulative effect  causes the anode current of one valve to reach maximum,  while that of the other valve is cut off or reduced. 
  D  )NPUT V !   $   
 CHAPTER  THIRTEEN  RADAR CLUTTER  13.1 INTRODUCTION TO RADAR CLUTfER  Clutter may be defined as any unwanted radar echo. Its name is descriptive of the fact that  such echoes can ••clutter" the radar output and make difficult the detection of wanted targets.  Examples of unwanted echoes, or clutter, in a radar designed to detect aircraft include the  reflections from land, sea, rain, birds, insects, and chaff. 
 HF OVER-THE-HORIZON RADAR  20.676x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 Several qualifiers should be kept in mind. At other geographic locations, the appro - priate CCIR noise should be selected or, better yet, noise measurements made in situ.  For radars that use auroral zone paths, specific analyses are required and target obscura - tion by spread-in-doppler clutter must be considered. 
 RANGE WINDOW CAN BE TOLERATED  A SUBSTANTIALLY REDUCED PROCESSING BANDWIDTH ALLOWS MORE ECONOMICAL !$ CONVERSION AND SUBSEQUENT DIGITAL SIGNAL PROCESSING )T ALSO ALLOWS A GREATER DYNAMIC RANGE TO BE ACHIEVED WITH LOWER 
 Perhaps the chief difficulty in trying to understand the nature ofclutter is  the lack of adequate quantitative descriptions of the nature of the scattering objects. In this  respect, the information regarding radar scattering from the sea is probably better understood  than radar scattering from the land. The state of the sea is determined primarily by the  Depression  Rodor 6 onqle  4  \  ,-- lnctdence angle  Figure 13.2 Angles used in describing geometry of  the radar and surface clutter. 
   42!#+).' 2!$!2   °ÓÇ 4HIS DISCUSSION OF TARGET NOISE IS BASED LARGELY ON AIRCRAFT  BUT IT IS GENERALLY APPLI 
 ,AVERTON!.&03 
 It can  be seen that a= c2/8<I~. The rms velocity spread <Iv is usually the preferred method for  describing the clutter fluctuation spectrum.  The improvement factor can be written as  I = (So/Co) = (So) x Ci = (So) x CA (4.20) S;/Cj ave Si ave Co Sj ave  where S0/C0 = output signal-to-clutter ratio, SdC; = input signal-to-clutter ratio, and  CA = clutter attentuation. 
 The operation ofthe circuits isasfollows. Tube Vlaand thefirst three elements ofVzform aflip-flop providing asquare wave, A,forintensifying the cathode-ray tube and atthe same time cutting offthecurrent from theplate ofVz,onwhich apositive sawtooth isformed bytheusual condenser charging circuit. One ofthehorizontal deflecting plates oftheCRT isdriven directly bythis sawtooth; theother, byanegative sawtooth provided bythe inverting amplifier V1~, which isprovided with cathode feedback. 
 CARRIER PHASE NOISE  LARGELY DUE TO THEIR HIGHER FREQUENCY OPERATION AND THE RESULTING  LOWER FREQUENCY MULTIPLICATION FACT OR REQUIRED TO GENERATE  THE EQUIVALENT RADAR 2& OUTPUT FREQUENCIES 6ERY ACCURATE FREQUENCY TIMING IS OFTEN REQUIRED IN RADARS WHERE COORDINATION OR  HAND 
 The pulse length isthen fixed by thetime required forthk negative wave totravel down theline and back tothegrid. Upon arrival atthegrid, thenegative wave drives thetube toward cutoff, aprocess helped again bythe regenerative action ofthe Practical Considerations. —The most economical pulser would have power flowing only during thepulse. 
 POLARIMETRIC 3!2 IMAGERY &EW DIHEDRALS EXIST IN + A 
 The existence of the relation expressed in Eq. 20.6  between the sea surface representation as a directional wave spectrum S( )k and the  doppler spectrum measured by an HF radar provides an opportunity to determine the  detailed state of the sea surface by remote sensing with skywave (or surface wave)  radar. In order to extract sea parameters from radar doppler spectra, and to optimize  the choice of radar parameters for the radar’s surveillance missions, it is helpful to  understand some elementary oceanography. 
 It also  is of relatively modest power for many radar applications.FIGURE 10. 4 Comparison of the structures of a conventional stagger-tuned klystron  (top) and clustered-cavity klystron (bottom)16 (Courtesy of the IEEE )RF inputRF outputIntermediate cavities Cathode Collector Stagger tuned klystron Intermediate cavity clusters Clustered–cavityTM klystronCathode CollectorRF input RF output ch10.indd   13 12/17/07   2:19:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 1551-1552, December, 1972.  16. Hsiao, J. 
 MENT OF THE KINEMATIC PARAMETERS POSITION  VELOCITY  AND ACCELERATION  OF TARGETS 4HE ESTIMATION  UPDATED WITH MEASUREMENTS  AND PREDICTION OF THE KINEMATIC PARAMETERS . 
 MTI usually refers to a radar in which the pulse repetition  frequency is clloseti low enougli to avoid ambiguities in range (no multiple-time-around  echoes). but with the consequence tliat tile frequency measurement is ambiguous and results in  blind speeds, Eq. (4.8). 
 Here mention will be made of a few aspects of the definitions that are of particular significance to the range prediction problem. Targets can be classified as either point targets or distributed targets. A point target is one for which (1) the maximum transverse separation of significant scat- tering elements is small compared with the length of the arc intercepted by the antenna beam at the target range and (2) the maximum radial separation of scat- tering elements is small compared with the range extent of the pulse. 
 If the  elemerlts were not isotropic but had a pattern Ee(O), and if the desired overall pattern were  denoted Ei8), the pattern to be found by synthesis using techniques derived for. isotropic  elements would be given by Ei8)/Ee(8).  Fourier-integral synthesis. 
 The result is that the electrons become “bunched” periodically. This bunching can  be thought of as producing a modulation of the density of electrons. The bunches  pass through the interaction space of the second cavity, which reinforces the density  modulation  to enhance the bunching. 
 Sea Clutter.  The reduction of sea clutter to levels acceptable to the user is a  far more difficult problem, and as yet, commercial radars do not meet all the ideal  demands of users. Small craft and buoys can easily be obscured in sea clutter. 
 Motkin. D. L.: Three-dimensional Air Surveillance Radar. 
 When the frequency is changed, the phase at the  radiating elements changes proportionately to the length of feed line so that the phase  at the aperture tilts in a linear manner and the beam is scanned. This effect is useful  for frequency-scanning techniques, but in the case of phased arrays, it is undesirable  and reduces the bandwidth. It has been shown previously that with phased arrays, the  pointing direction of a scanned beam also changes with frequency (Eq. 
 Phys. , vol. 31, pp. 
 the lower the frcqircncy that can be propagated. as can'be seen I'rom  Eq. (12.13). 
 V ., pp. 665–668. 117. 
 78 PROPERTIES OF RADAR TARGETS [SEC. 39 m=l.1) I:I,:.310.-l’rartional modulating ofret”,-ned signal from aB-26 athlac!e frequent>-; left propeller rotating, right propeller stationary. chosen as5sec. 
 11.1 ). The pulse uncorrupted by noise is shown by the solid curve. The shape  of the pulse is not perfectly rectangular; the rise and decay times are not zero, for this would  require an mfinite bandwidth. 
 McGraw-llill  Book Co., New York, 1970.  2. Boot, H. 
 I_9 Modeling, of propagation, 26.13 to 26.17 Modified generalized sign test processor, 7.17 to 7.19 Modulators, 10.23 to 10.25 Monopulse-antenna feed techniques, 9.6 to 9.10 Monopulse antenna feeds, 12.26 to 12.28 Monopulse, dual band, 9.24 to 9.25 Monopulse, and ECM, 24.23 to 24.24, 24.42 to 24.43 Monopulse, phased arrays, 13.4 Monopulse tracking, 9. 3 to 9.16 Moving Target Indication (MTI), 1.5, 4.2 A/D converter effect on dynamic range, 2.78 to 2.80 adaptive, 2.80 to 2.83 binomial weight cancelers, 2. 35 and birds as clutter, 2.85, 2.87 to 2.88, 2.96 to 2.98 blind speeds, 2.9 to 2.10 block diagram, 2. 
 Thirdly, ASV is required to provide a means whereby an aircraft can ﬁx its position, home on to a base on land or water, and thereafter, if necessary, make a beam approach with minimum external human aid. Such provisions as may be necessary tointerrogate beacons from the ASV directly, or alternately from ancillary apparatus, and appropriately to receive and display the response, depend on policy decisions as to the nature of the beacon system generally adopted. Requirements to Meet the Aim doi:10.1088/978-1-6432-7066-1ch3 3-1 ªMorgan & Claypool Publishers 2018. 
 Another advantage is that  a deflection of the planar mirror by an angle 0 results in the beam scanning through an angle  20,  A similar principle is used in the configuration shown in Fig. 7.14 to obtain a 360"  rotating-bca~n antctirla without the need for RF rotary joints. 111 this cutaway sketch, four  polarization sensitive parabolic reflectors surround a rotating twist-reflector mirror. 
 FED REFLECTORS  THIS METHOD DOES NOT WORK AS WELL AS THE MORE RIGOROUS PHYSICAL OPTICS 0/  METHOD THAT IS DESCRIBED IN 3ECTION  &OR THE SIMPLE CENTER 
 Figure 16.6 a shows a number  of facets of different sizes contributing to a radar return. ch16.indd   8 12/19/07   4:54:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 and the receiver is tutied to a strong cross-product such as 2fi + fi. When receiving  at a frcquetlcy different from that transmitted, care must be exercised to ensure that the  trarlsrnitter signal does not radiate a significant spectral component at the frequency to which  tlie receiver is tuned.  'The arnourit of signal returned fro111 a nonlinear contact at a harmonic frequency is a  nonlinear function of the incident field strength. 
    A     A      B     B      B    
 Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 19.40  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 in Europe cover the lower atmospheric winds up to 3–5 km (or a few km higher with  larger antennas) where the strong moisture fluctuations present in the atmospheric  boundary layer provide strong scattering signatures at these shorter wavelengths.  These UHF boundary-layer wind profilers are typically used for air pollution moni - toring and warnings as well as various research applications. 
 Clearly, s  0 must be measured with an accuracy and  precision of less than 1 dB if useful wind retrievals are to be derived. Accuracy depends  on the radar’s stability and its calibration. The challenge for space-borne scatterometry  is to design the radar such that the precision—the normalized standard deviation of the  s  0 measurements—is sufficiently small. 
 1977.  OTHER RADAR TOPICS569 72.Godlove. T.F.•V.L.Granatstein, andJ.Silverstein: Prospects forHighPowerMillimeter Radar Sources andComponent!>." IEEEEASCON-77 Record. 
 DELAY CORRECTIONS SHOULD BE AVOIDED AS THEY CAN CAUSE PROBLEMS ALIGNING THE ) AND 1 DIGITAL DATA 7HEN ADDING TIME DELAY TO THE SAMPLE CLOCK  CARE MUST BE  TAKEN TO AVOID ADDING JITTER  WHICH COULD DEGRADE THE !$ CONVERTER 3.2 PERFORMANCE 4IME 
 It pro- vides a symmetry so that when the spot is centered equal energy falls on each of the four horns. However, if the target moves off axis, causing the spot to shift, there is an unbalance of energy in the horns. The radar senses the target displace- ment by comparing the amplitude of the echo signal excited in each of the horns. 
 Laws, J. O., and D. A. 
 D" RANGE RESOLUTION WIDTH WITH (AMMING WEIGHTING APPLIED OVER THE  
 The feedback integrator8,9 and two-pole  filter10,11 are detectors that minimize the data storage requirements. While these detec - tors may still be found in older radars, they probably would not be implemented in  new radars and will not be discussed in this edition. Though all the detectors are  shown in Figure 7.3 as being constructed with shift registers, they would normally be  implemented with random-access memory. 
 The phase ofeach subpulse is chosen to  be either 0 or n radians. If the selection of the 0, n phase is made at random, the waveform  approximates a noise-modulated signal with a thumbtack ambiguity function, as in  Fig. 11.13~. 
 But consider the two signals at B and C, representing target echoes of equal amplitude. The  noise voltage accompanying the signal at Bis large enough so that the combination of signal  plus noise exceeds the threshold. At C the noise is not as large and the resultant signal plus  noise does not cross the threshold. 
 ( d) The result of RCS curve denoising. Figure 7. Comparison of the percentage error for aspect entropy calculation. 
 TIii' FI.FCIRONICALLY STEERED PHASFLJ ARRAY ANTENNA IN RADAR 335  orthogonal coordinate. This approach is generally easier than using phase shifters to  scan in both coordinates. but as with any frequency-scanned array the use of the  rrequency domain ror other purposes is limited when frequency is employed for  hea 111-st eeri n g. 
 LAUNCHER  B  )MAGE OF TRACTOR 
 MAP WIDTH  WHICH IS CONSIDERABLY LARGER THAN THE CONVENTIONAL AMBIGUITY CONSTRAINT WOULD ALLOW .ORMALLY  THE TRADE 
 Theproblem withmillimeter wavelengths isthatseveralofitsfavorable characteristics arealsofactorsthatlimititsperformance; in particular, thesmallantenna sizeandtheconsequences ofitscharacteristic wavelengths. Thephysically smallantenna sizesatmillimeter wavelengths resultinhighgain.butthe. 562 INTRODUCTION TO RADAR SYSTEMS  small area means that less of the echo energy will be collected by the antenna. 
 16.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Scatterometers capable of measuring response over a wide range of frequencies are  called spectrometers .83 Various antenna patterns from pencil beams to fan beams may  be used. Systems to measure the full polarization matrix must use very careful antenna  designs so that the phases of the different transmitted and received polarizations are  well controlled, and leakage between polarizations is thoroughly suppressed. CW and FM-CW Systems. 
 TIME LOCATION THAT MAXIMIZES THE 3.2 FOR  THE GIVEN TARGET  TAKING ALL RADAR EQUATION FACTORS INTO ACCOUNT !GAIN  A CONTOUR PLOT FORMAT IS USED HERE IN &IGURE  /THER -ODELING !PPROACHES  4HE MODELS DESCRIBED ABOVE ARE FORMULATED IN THE  CONTEXT OF THE RADAR EQUATION %Q   !N ALTERNATIVE IS TO EMPLOY A COHERENT hPRO 
 Air-to-surface search radars, as well as airborne battlefield surveillance ra- dars, are designed to maximize detection of slowly moving targets. Higher- . Af fr FIG. 
   -ARS 'LOBAL 3URVEYOR  AND  -ARS  %XPRESS 6ENUS MEASUREMENTS WERE MADE BY  6ENERAS 
 The radiated signal f~om tlie bistatic transmitter as shown in Fig. 14.12 arrives at the  receiver via two sepa~atc putlis, one being tlle dirx~ct patli from transmitter to receiver, tlie  otlicr [wing tlie sc.trttt>r.cd pat11 wliich includes the target. Tlie measurements which can be  made at thc bistatic rccciver arc:  1. 
 LAYER ION 
 E. Conte and A. De Maio, “Mitigation techniques for non-gaussian sea clutter,” IEEE Journal of  Oceanic Engineering , vol. 
 BASED 3!2 IS  R66 $ !Z "EAM 3# !Z      RATHER THAN THE FAMOUS hONE HALF OF THE  APERTURE LENGTHv OF AIRBORNE 3!2S .OTE THAT  6"EAM IS ALWAYS SMALLER THAN THE SPACE 
 MULTIPLEXED  TO ESTIMATE AND COMPENSATE FOR PROPAGATION DELAYS   IMPOSED BY IONOSPHERIC ELECTRONS $ESIGNED FOR AN INITIAL THREE 
 Thereceiving beam-forming network maybeatIForRF.Tappeddelaylineshavebeena. I I lfi lil.l:('l K0NI~'AI.I.Y Sfli1iRI:l) PlfASEU ARRAY ANTENNA IN RADAK 31 1  Amplifier Q  111  Beom Beom Beam  No. 3 N0.2 No. 
 BASED DUCTS OCCUR WHEN THE AIR ALOFT IS EXCEPTIONALLY WARM AND DRY COM 
 BEAM TUBE !LTHOUGH IT HAS SOME ADVANTAGES NOT FOUND IN OTHER TUBES  IT HAS LOWER GAIN THAN LINEAR 
 I:! of Ratltrr Mtrt~rlhoorC, M. I.  Skolnik (ed.), McGraw-Hill Book Co., New York, 1970. 
 A time delay can be implemented with a FIR filter that  imposes a linearly changing phase shift over frequency on the signal. Once the time  delay is realized in each channel, the appropriate complex time-delayed signals from  all of the channels are summed to form a beam. M complex summers are required to  form M beams. 
 GATE 
 2AYLEIGH DENSITY  &URTHERMORE  THE BATCH PROCESSOR REQUIRES LESS STORAGE  DETECTS BETTER  AND ESTIMATES  &)'52%  #OMPARISON OF BINARY INTEGRATOR  - 
 A more severe problem occurs ·when a seaborne radar must operate near land. Land  clutter can be so large that clutter echoes might enter the radar receiver via the antenn.i . RADAR CLUTTER 483  sidelobes. 
 Vivekanandan, G. Zhang, S.M. Ellis, D. 
 A threshold is established at the output of the video amplifier to allow the de- tection decision to be made. If the receiver output crosses the threshold, a target is said to be present. The decision may be made by an operator, or it might be done with an automatic detector without operator intervention. 
 TORTION COMMENSURATE WITH THE ASSOCIATED FEED DISPLACEMENT )F AN %3! FEED IS USED  THE REFLECTOR SYSTEM CAN BE DESIGNED TO ENABLE ELECTRONIC BEAM SCANNING  ALBEIT OVER A LIMITED &/6 4HE USE OF MODERN %3! AND %3! 
 WATER DROP !T WAVELENGTHS OF  AND  CM WITH  A    A   RADIUS OF DROP   +ERKER  ,ANGLEBEN   AND 'UNN  FOUND THAT PARTICLES ATTAINED TOTAL ATTENUATION CROSS SECTIONS CORRESPONDING TO  ALL MELTED PARTICLES WHEN LESS THAN  OF THE ICE PARTICLES WAS MELTED 7HEN THE MELTED 4!",%  #ORRECTION &ACTOR -ULTIPLICATIVE  FOR 2AINFALL !TTENUATION 0RECIPITATION   2ATE 2  MMH K  CM n#  n#  n#  n#  n#                                                                                                                                                                            . 
 Stark, R. W. Burns, and W. 
 abriefreviewwillbegivenof thevariousTadar-ECCM options thatcanmakethetaskofECMmoredifficult. Asageneral rule,goodradardesignpractice canreducevulnerability toelectronic countermeasures. Gooddesignisbasedonmaximizing theratioofthesignalenergytonoise powerperhertz(EINo),aswellasemploying techniques toreducemutualinterference. 
 Spot chaff is dropped as  individual bundles which appear as additional targets on the radar in an effort to dcceivc the  operator as to their true nature.  A chaff corridor is produced by air.craft continuously releasing chaff to form a long  corridorlike cloud through which following aircraft can fly undetected. The effect is to mask  the aircraft, much like a smoke screen. 
 Audiofrequencies II .. •,Microwave rtQion Videofrequencies•II I I I I -- 30Hz300Hz 3kHz 30kHz 300kHz 3MHz 30MHz 300MHz3GHz Frequency30GHz 300GHz 3,000GHz Figure1.4Radarfrequencies andtheelectromagnetic spectrum.. 8 INTRODUCTION TO RADAR SYSTEMS  Table 1.1 Standard radar-frequency letter-band nomenclature  Specific radiolocatio~l  Band Nominal (radar) bands based on  designation frequency range ITU assignments for region 2  HF  VHF  UHF  K  K,  rnrn 138-144 MHz  2 16-225  420-450 MHz  890-942  1215-1400 MHz  2300-2500 MHz  2 700-3 700  5250-5925 MHz  8500- 10,680 MHz  13.4-14.0 GHz  15.7- 17.7  24.05-24.25 GHz  33.4-36.0 GHz  substitute for the actual numerical frequency limits of radars. 
 NOISE PEAKS 4HIS RESULTS IN A SMALLER RMS TRACKING NOISE WITH A SLOW !'# SYSTEM   (OWEVER  THIS REASONING NEGLECTS AN ADDITIONAL NOISE TERM  CAUSED BY THE LACK OF  FULL !'# ACTION  WHICH IS PROPORTIONAL TO TRACKING LAG ! TRACKING LAG CAUSES A DC ERROR  . °Î{  2!$!2 (!.$"//+  VOLTAGE IN THE ANGLE 
 PassiveECM.Thenoisejammer andtherepeater jammer wereexamples ofactiveECM. Theyinternally generate oramplify electromagnetic energy, whichisthenradiated. Passive electronic countermeasures donotgenerate oramplifyelectromagnetic radiation. 
 TIME PROCESSING /N THE OTHER HAND  FINE  CROSSRANGE RESOLUTION REQUIRES MULTIPLE PULSES  AND THE CORRESPONDING PROCESSING IS  THEREFORE  OFTEN TERMED SLOW 
 SIGHT AND ITS PERPENDICULAR IN THE GROUND PLANE  'ROUND 
 18.22  18.5 Target Acquisition and Range Tracking   .................  18.26  Acquisition  .........................................................  18.26  Range Tracking  ................................................. 
 The  former are predictable, but the latter are not and can only be described in statistical terms . ...  Examples of systematic errors include (1) mutual coupling between the elements of an array,  (2) aperture blocking in reflector antennas due to the feed and its supports, (3) diffraction at  the steps in a zoned-lens antenna, and (4) periodicities included in the construction of the  antenna. 
 (Courtesy  Varian Associates, Inc., Be,,erly, M.4.) . RADAR TRANSMITTERS 199  I\ measure of the effect of the load on the magnetron frequency is the pulling figure,  defined as the <liITcrcnce between the maximum and minimum frequencies when the phase  angle of the load varies through 3600 and the magnitude of the VSWR is fixed at 1.5 (or a  rellcction coefficient of 0.20). The pulling figure is readily obtained from an inspection of the  Ricke diagram. 
 45. Fried. W. 
 In the other, the video signal expericnccs a  time delay equal to one pulse-repetition period (equal to the reciprocal of the pulse-repetition  frequency). The outputs from the two channels are subtracted from one another. The fixed  targets with unchanging amplitudes from pulse to pulse are canceled on subtraction. 
 MING  THE RADAR CAN MAXIMIZE THE RECEIVED TARGET ENERGY BY TRANSMITTING MORE AVERAGE POWER  DWELLING LONGER ON THE TARGET  OR INCREASING THE ANTENNA GAIN )F THE RADARS DATA RATE IS FIXED AND A UNIFORM ANGULAR SEARCH RATE IS DICTATED BY MECHANICAL OR SEARCH STRATEGY  THEN THE ONLY OPTION FOR THE RADAR IS TO INCREASE ITS AVERAGE TRANSMITTER POWER 4HE NEXT OPTION IS TO MANAGE THE DATA RATE  THEREBY ALLOWING A LONGER DWELL TIME ON THE TARGET BURNTHROUGH MODE  ALONG SPECIFIC SPATIAL SECTORS WHERE  NEEDED 4HE ABILITY TO  VARY THE DATA RATE IN AN OPTIMAL MANNER IS ONE OF THE PRINCIPAL ADVANTAGES OF PHASED 
 FIGURE 21.16  Typical sampling receiver used for time-domain GPR systemsTransmitter  Antenna Receive  Antenna Ch 1Ch 1 I/O8 Bit Control 16 Bit Data  OutputGEN DELAY CLOCK TVG HOLD ADCSAMPLING  CONTROL SAMPLING  HEADA A ch21.indd   22 12/17/07   2:51:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 
 Objects with possibility of movement are labeled and compared against the areas in the change maps. It should also be noted that only some parts of an object can be detected as a change, and these detected changes can be used as a guide to extract the full object. After this process, the labeled areas in the change maps are overlaid on the reference image and checked whether they are a part of a larger object in the image. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.94  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 The result from this subtraction process is that the fixed clutter is removed, and moving  targets are retained. The output from the first pulse is not used, making this type of MTI  filter time-variant. 
 Brunner, A.: Possibilities of Dimensioning Doubly Curved Reflectors ror Azimuth-Search Radar  Antennas, IEEE Trans., vol. AP-19, pp. 52-57, January, 1971. 
 TO 
 +1/"  "ENCHMARK 2ANGE #ONCEPT  5NLIKE A MONOSTATIC RADAR  THE RANGE PERFORMANCE  OF A BISTATIC RADAR IS A FUNCTION OF THE GEOMETRY  SPECIFICALLY THE BASELINE RANGE  , AND  AN ANTENNA LOOK ANGLE  EITHER  P4 OR P2 7HEN FACTORS SUCH A DIFFRACTION  REFRACTION   MULTIPATH  AND MASKING ARE ABSENT OR CAN BE IGNORED  BISTATIC RANGE AS A FUNCTION OF THESE VARIABLES CAN BE PLOTTED ON THE BISTATIC PLANE USING AN OVAL OF #ASSINI !N OVAL OF #ASSINI IS THE LOCUS OF THE VERTEX OF A TRIANGLE WHEN THE PRODUCT OF THE SIDES ADJACENT TO THE VERTEX IS CONSTANT AND THE LENGTH OF THE OPPOSITE SIDE IS FIXED 7HEN APPLIED TO THE BISTATIC TRIANGLE SHOWN IN &IGURE   THE VERTEX IS AT THE TARGET  2 4 AND  22 ARE THE SIDES ADJACENT TO THE VERTEX AND THE BASELINE  , IS THE LENGTH OF THE FIXED   OPPOSITE SIDE 4RADITIONALLY  OVALS OF #ASSINI ARE DRAWN AS CONTOURS OF A CONSTANT RECEIVED SIGNAL  POWER OR A RECEIVED SIGNAL 
 A good radar design is one whicli is not overly sensitive to small  v;lrintions it1 tl~c rriodcl or tlie assunlptions.  Atmospheric and urban noise. A single lightning stroke radiates considerable RF noise  power. 
 908–917, August 1985. 70. R. 
 31,  pp. 325–332, May 1988. ch13.indd   74 12/17/07   2:41:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
  
 Since this isasingle-valued method, no zero-phase adjustment need bemade. Itcantherefore beused for sector scanning, orforint,errupted scanning. Thedatacan beused toposition ascan converter bymeans ofaphase-sensitive mecha- nism, orthey can beused directly toprovide electrical information forsuch anindicator asaB-scope. 
 ti011 of targets it1 sea ~It~tter,~~~~~ it is prolxtt~ly more i~sefi~l for operation in precipitation  clutter. Siicli cliittcr is niorc likely to 1)e Rnyleigli tlia~i sea cliitter (Sec. 13.3) or larid cliitter  (Sec. 
 The following example illustrates how SAR  crossrange resolution has improved as the preceding types of airborne mapping radar  were developed. Let us assume that l = 0.03 m (X band), D = aperture diameter =   2 m, R = 100 km, qsq = 0, V = 180 m/sec, LDBS = 10 m (corresponding to an angular  scan rate of 15° sec), and spotlight synthetic aperture length = 5 km ( ∆q ≈ 3 deg).   ch17.indd   5 12/17/07   6:48:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
    B. 
 3/* AND ! 
 J.: Clutter and Its Reduction on Shipborne Radars, lt~terr~atiotrul Cottfere~lce otr Radtir  I'rcpset~t t111d F'~rtrtrr. Oct. 23--25, 1973. 
 For example, wind speed certainly seems to affect clutter levels, but correlation of clutter with, say, ships' anemom- eter readings has not been entirely satisfactory. The state of agitation of the sur- face (sea state) appears to have a strong effect, but it is a subjective measure, and its relation to the prevailing local winds is often uncertain. Moreover, it has been found that the temperatures of the air and the sea surface can affect the way in which the measured wind speed is related to the generation of clutter-producing waves, yet the importance of these effects were unappreciated over most of the history of sea clutter measurements; so air and sea temperatures were seldom recorded. 
 SURFACE TOPOGRAPHIC VARIATIONS  ORBITS ARE REQUIRED THAT GENERATE DENSE TRACK 
 Whicker, L. R., and R. R. 
 SPONDING PROCESS TIMESCALE  SUCH AS I  PULSEWAVEFORM REPETITION INTERVAL  II  COHERENT  INTEGRATION DWELL  TIME  III  SCAN REVISIT TIME  OR IV  MISSION  TRACK LIFETIME $YNAMICAL PROCESSES IMPACT DIRECTLY ON HOW ONE SHOULD PROCESS THE RECEIVED SIGNALS OR PERFORM TRACKING 3LOW PROCESSES  SUCH AS THE  
 14.5 might be modified to produce a noise- quieting servo. Practical considerations have resulted in a wide variety of additional schemes. The simplest is the introduction of a high-g cavity between a klystron driver and the power amplifiers. 
 TO 
  D" AT THE EDGES OF THE BAND WITH  n OF SCAN )NTERLACING OF SUBARRAYS CAN  REDUCE THE GRATING LOBES &)'52%   0HASED ARRAY USING SUBARRAYS WITH TIME DELAY . £Î°{{  2!$!2 (!.$"//+  4HE MONOPULSE NULL POSITION IS UNAFFECTED BY THE BEHAVIOR OF THE SUBARRAYS AS LONG  AS THEY ALL RESPOND IN THE SAME WAY 4HE NULL POSITION IS DETERMINED ONLY BY THE TIME 
 BAND AND +A 
 Three beams are used with a beam spacing of 20◦and the beam width is 2.86◦. There are ﬁve points in the scene, and the simulation scenario layout is shown in Figure 10. The center point target is located at (0, 0), and the remaining four points are located at ( ±30,±30). 
 Dhar, “A model for target detection with over-the-horizon radar,” IEEE Trans.  AES, vol. 26, pp. 
 These pitch and yaw error signals are used to close the antenna tracking loop and to guide the missile. The guidance error signal must be normalized (a constant scale factor of volts per degree off boresight is required) over the full dynamic range of target signal amplitudes (range, target size) in the presence of large feedthrough and clutter signals. Therefore, AGC in the receiver is necessary. 
 TO 
 POINT &&4 CONSISTS OF THREE STAGES !LL OF THE COMPUTATIONS IN EACH  STAGE ARE EXECUTED BEFORE PROCEEDING TO THE NEXT STAGE !LSO NOTE THAT THE PHASE SHIFT IN THE FIRST STAGE  7   IS ZERO  WHICH REQUIRES NO COMPUTATION AT ALL&)'52%    2ADIX 
 TO 
 8-10, 1978. 15. Claassen, J. 
 585--587, June, 1975.  75. Brown, B. 
 If  narrow bearnwidths are to be achieved, the radar antenna must be a physically large phased  array. A one-degree beamwidth, for example, requires an aperture of about 1200 m at a  frequency of 15 MHz. Since the transmitting antenna must handle high power, it is more  costly to obtain than large receiving apertures. 
 Five sectors of current surveillance activity are shown, each  addressing a particular mission as indicated, each mission consisting of a number of  dwell interrogation regions (DIRs) . The electronically steered radar transmit beam  steps through these DIRs, in some assigned sequence, illuminating each DIR with an  appropriate waveform for a corresponding interval during which the receiving system  acquires a coherent time series of echo samples. The coherent integration time (CIT)  depends on the type of observation but is almost always in the range of 1–100 seconds. 
 Translation motion is the main cause of image defocusing. Motion compensation can eliminate the translation motion affection on image. It is a signiﬁcant step of inverse synthetic aperture radar (ISAR) processing for refocusing moving target. 
 With prf-2, the aircraft velocity is shown competing with the rain  clutter; but with prf-1 it appears in one filter (No. 6) without any rain clutter). Thus, by  using two prf's which are alternated every 10 pulses (one-half beamwidth), aircraft targets will  usui~lly appear in at least one filter free from rain except for a sinall region (approximately 30  kriots wide) wiierl tlie target's radial velocity is exactly that of the rain. 
 This backward reflected energy is also received by the radar and may inter - fere with the radar’s ability to distinguish a desired target. This backward reflected  energy is called clutter . Not only is the magnitude of the reflected wave reduced, but also the phase of the  wave is altered. 
 In Proceedings of the 2010 IEEE International Geoscience and Remote Sensing Symposium, Honolulu, HI, USA, 25–30 July 2010; pp. 3490–3493. 20. 
 K. Li, D. Callahan, D. 
 Each ofthese higher modes has itsown characteristic electromagnetic field configuration. ordinarily itisadvisable toavoid propagation inmore than one mode, and this is most easily done bychoosing the dimensions ofthe guide sothat the lowest mode, and the lowest mode only, can propagate. However, for certain applications some ofthe higher modes are useful. 
 4. Results and V alidation4.1. Rates of Land Subsidence Figure 4shows the average subsidence velocity in the radar LOS from October 2015 to June 2018 across Wuhan city by using SBAS-InSAR technique. 
 and A. Spizzichino: "The Scattering of Electromiignetic Wavcs frorn Rougll Sirr-  faces," The Macmillan Company, New York. 1963. 
 TRACKING FILTERS  EACH EMPLOYING A DIFFERENT TARGET MOTION MODEL   AFTER 3 "LACKMAN AND 2 0OPOLI Ú !RTECH (OUSE   &)'52%  &LOWCHART OF INTERACTING MULTIPLE MODELS  AFTER 3 "LACKMAN AND 2 0OPOLI  Ú !RTECH (OUSE  . 
 The  array can he made to simultaneously generate many search and/or tracking beams with the  same aperture.  Other types of array antennas are possible than the linear or the planar arrangements.  For example, the elements might be arranged on the surface of a cylinder to obtain 360°  coverage (360° coverage may also be obtained with a number of planar arrays). 
 WAVE RANGE  THE SINGLE 
 The number of filters depends on the antenna beamwidth and  302INTRODUCTION TORADAR SYSTEMS Figure8.17AN/SPS-48 frequency-scan radarantenna. elevation angleincreases, thetransmitted powerisdecreased astheelevation angleisin­ creased. (Thisissometimes calledpowerprogramming.) Inashipboard application, theeleva­ tionscanning controlcanbe usedtoelectronically stabilize thebeamposition tocompensate forship'smotion. 
 58  8.7.2 Example s for Incoherent Integration ......................................................................... 60  8.8 Pulse Compression for Improving the Resolution .......................................................... 62  8.8.1 Compression of a frequency modulated pulse (chirp) .............................................. 
 George, and 0. D. Sledge: The Possibility of Cross Modulation in the SCAMP Signal  Processor, Proc. 
 The  rough surface causes significant diffuse scattering rather than a mirror reflection. This  changes the shape of the error curve and results in some residual elevation-angle error  when the target elevation goes to zero. It also causes some significant azimuth error.46 Crosstalk Caused by Cross-Polarized Energy. 
 A phase change pulse-to-pulse of 0.01 radians results in an improvement-factor limitation of  40 dB. I'lie limits to tlie improvement factor imposed by pulse-to-pulse instability are listed  below :R.J6.47  Transmitter frequency (~Afr)-~  Stalo or coho frequency (2n A f T)-2  Transmitter phase shift (A@)--'  Coho lockirlg (A+) --  Pulse timing ~~/(At)~2Br  Pulse width r2/(Ar)'Br  Pulse amplitude (AIAA )2  where A/ = interpulse frequency change, r = pulse width, 'r = transmission time to and from  target, Aq5 = interpulse phase change, At = time jitter, Br = time-bandwidth product of pulse  cornpression systern (= unity for simple pulses,) As = pulse-width jitter, A = pulse amplitude,  A,1 = interpulse amplitude cl~atige. In a digital signal processor tlie improvement factor is also  limited by the quantization noise introduced by the AID converter, as was discussed in  Sec. 
 (Fig. 6.31.) All ofthe AN/APS-4 except the indicator and the controls is mounted ina“bomb” hung under the plane onthe conventional bomb shackles (Fig. 6.32). 
 2017 ,46, 1717–1733. 11. Lin, H.; Ma, P .; Wang, W. 
 139. Steinberg, B. D.: The Peak Sidelobe of the Phased Array Having Randomly ~ocated Elements, I £EE  Trans .. 
 The initial trials were  conducted in the Great Lakes and were overseen by the Coast Guard. The radar standards proposed in 1946 were not adopted internationally, although  the UK issued national performance standards based on them in 1948. The UK stan - dard was also adopted by a number of other countries. 
 161. S. J. 
 The presence of additional  spikes can lead to ambiguity in the measurement of target parameters. An ambiguous measure-  ment is one in which there is more than one choice available for the correct value of a  parameter, but only one choice is appropriate. Thus the correct value is uncertain. 
 HF OVER-THE-HORIZON RADAR  20.416x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 The practice in allocations for HF radar operation is to permit use of broad bands  of the spectrum with a requirement to cause no discernible interference to an existing  service and to provide a lockout feature for channels that need protection. Thus, an  integral part of an HF radar is a channel occupancy analyzer that provides a real-time  description of spectrum availability, as illustrated in Figures 20.17 and 20.18. FIGURE 20.17  A snapshot of the HF spectrum at noon in summer and at a low sunspot number, zoom - ing in progressively to show a section of the spectrum where a 20 kHz clear channel is evident, centered  on 15.640 MHz. 
 12.5. Hering. K. 
 H.: The Fast Fourier Transform and the Butler Matrix, IEEE Tra11s., vol. AP-16, p. 360,  May, 1968. 
 H., 26  Beliringer, C. C. E., 28  Boot, H. 
 W.: Bistatic Cross Section of the Sea for Beaufort 5 Sea, Science Technol., vol. 17, American Astronautical Society, San Diego, 1968, pp. 447-448. 
 O. M. Phillips, F. 
 The well-recognized benefits oflow-noise receivers, combined withtheirrelativealTordability. makethemanattractive featureinmodern radardesign.However, low-noise receivers are somctimes accompanied byotherlessdesirable properties thattendtoresultinacompromise inreceivcrperformance. Thusalow-noise receiver mightnotalwaysbetheobvious selection. 
 Thissum,whenmultiplied bytheappropriate constant, determines thethreshold levelforachieving thedesired probability offalsealarm.Thus thethreshold variescontinuously according ''Jthenoiseartheclutterenvironment fmmd withinarangeintervalsurrounding therangecellunderobservation.76ThisformofCFAR hassometimes beencalledAdaptive VideoThreshold, orAVT.Theparticular CFARshownin Fig.tO.11doesnotsumalltherangecellsasdescribed above,butsumsthecellsaheadofthe testcellseparately fromthesumofthecellsfollowing thetestcell.Thethreshoid isdetermined bywhichever ofthetwosumsisthegreater.Thisisdonetominirizethegeneration offalse alarmsattheleadingandtrailingedgesofabruptclutterregions. ";<\smalladditional lossis incurred, however, compared tousingallthetapstoestablish the;hreshold. (Forexample, with32reference cells,a10-5probability offalsealarm,and0.9probability ofdetection, the. 
 Effects of Roughness, Moisture Content, and Vegetation Cover.  Scattering  falls off more rapidly with angles for smooth surfaces than for rough surfaces. Since  the roughness that affects radar must be measured in wavelength units, a surface smooth  at long wavelengths may be rough at shorter ones. 
 The objective of the MBC is to sup - press high duty cycle and NLI received through the main beam of the radar. The  conceptual scheme of MBC is analogous to the scheme of SLC; however, high gain  beams are employed in lieu of low gain auxiliary antennas. Jamming is cancelled by a  linear combination of the signals from the high gain beams and the main antenna. 
 In this case, activity control effectively eliminates most of the  clutter detections without eliminating many of the actual target detections. However,  because this process essentially constitutes controlled desensitization of the radar, it  must be used with care. The mapping of the detection activity must be precise so that  desensitization occurs only in those regions requiring it. 
 At wavelengths greater than about 25cm, beam-shaping toeliminate the undesirable effects ofradiation striking the earth’s surface is nolonger feasible. 2.Coverage. Ifcharacteristics other than antenna height areheld constant, then maximum detection range decreases slowly as wavelength decreases, but the antenna height required for the maintenance ofagiven elevation coverage varies directly with wavelength.. 
 The phase of the coho is then related to the phase of the transmitted pulse and  may be used as the reference signal for echoes received from that particular transmitted pulse.  Upon the next transmission another IF locking pulse is generated to relock the phase of the  CW coho until the next locking pulse comes along. The type of MTI radar illustrated in  Fig. 
 To construct the diagram, a large phasor is drawn to represent the carrier. This is taken as a reference and is considered sta- tionary; higher frequencies are represented by phasors rotating counterclockwise and lower frequencies by phasors rotating clockwise. In applying the phasor method to FM homodyne radar, the instantaneous phase of the local oscillator (i.e., that of the transmitter) is taken as the reference phasor, and the returning signal or signals as the small phasor or phasors. 
 pp. 73--78. IEEE Publ. 
 56–61, August 16, 1965. 56. Technology in the National Interest , Lexington, MA: MIT Lincoln Laboratory, 1995. 
 Hansen69) ch15.indd   23 12/15/07   6:17:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter. 
 Informed witnesses of that event  affirm that America was astonished at the generosity of  the gift conveyed by Sir Henry’s mission, that she was  amazed at the progress our scientists had made in  branches of physics of which our transatlantic colleagues  had almost no knowledge, and that the nation-to-nation  gift of radar was the greatest single act of friendship  between the English-speaking peoples.  Progress in radar, even for war application, was by  no means near the end, however. American and British  teams worked together. 
 A special class of binary codes is the Barker21 codes. The peak of the autocorrelation function is N9 and the magnitude of the minimum peak sidelobe is 1, where N is the number of subpulses or length of the code. Only a small number of these codes exist. 
 SCALE ROUGHNESS AND MATERIAL DENSITIES IN THE TOP FEW CENTIMETERS OF REGOLITH 3PECIAL GEOMETRIES  SUCH AS NEAR 
 SPACE PATH LOSS 4HE POWER DENSITY  0 A   OVER A SPHERE AT ANY POINT IN FREE SPACE IS   00' RATT ¤ ¦¥³ µ´ O 7M    WHERE 0T IS THE POWER RADIATED BY THE TRANSMITTER   R IS THE RADIUS OF THE SPHERE  AND  'T IS  THE TRANSMITTING ANTENNAS GAIN &OR A LOSS 
 A duct is produced when the index of refraction decreases with altitude at a rapid rate. If  the index of refraction [Eq. (12.9)] is to decrease.with height, the temperature must increase  and/or the humidity (water-vapor content) must decrease with height. 
 119-140, 1956.  32. Li, T.: A Study of Spherical Reflectors as Wide-angle Scanning Antennas. 
 FED FEED LINES ARE USED AND COMBINED IN A  NETWORK TO GIVE SUM 
 A.: The Operator Factor Concept, Its History and Present Status, Symposium on Radar  Detection Theory, ONR Symposium Report ACR-10, Mar. 1-2, 1956, DDC No. 117533. 
 652 MOVING-TARGET INDICATION [SEC 16.9 clutter has tocompete with theclutter-noise inmuch thesame way asa target intheclear competes with ordinary receiver noise. Figure 16.23is avector diagram foramoving target intheclutter. The pulse-to-pulse variation rinthe resultant vector has both amplitude and phase com- ponents just like theclutter fluctuations. 
 POLEnDOUBLE 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.60  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 A number of birds are shown on the display. 
 Thuspulse-to-pulse frequency changes (frequency .agility) ofIItorgreaterwilldecorrelate theclutterandpermitanincrease in target-to-clutter ratiowhenthedecorrelated pulsesareintegrated. Withahigh-resolution radarinwhichthepersistent sea-clutter spikesappear,thebenefitoffrequency agilityis decreased sincetheseaspikesarecorrelated overarelatively longperiodoftimeandappear similartotargetechoes.Thusfrequency agilitywillbeoflessvaluethemorenon-Rayleigh the clutterstatistics. (Iftheradarisonarapidlymoving platform, thecluttermightalsobe decorrelated astheradarresolution cellviewsadifferent patchofclutter.) Receiver detection criteria. 
 We shall discuss first the absorption bythe gases ofthe atmosphere. Ofthe three abundant gases ofthe atmosphere—nitrogen, oxygen, and water vapor—the latter two areintrinsically capable ofinteracting with and absorbing energy from aradio wave byvirtue ofthepermanent electric dipole moment ofthe water molecule and the permanent mag- neticdipole moment ofthe oxygen molecule. We know, however, that molecules absorb radiation inmore orless well-defined absorption lines, orbands, and wehave toinquire whether either ofthese molecules exhibits absorption lines inthemicrowave range—that is,atfrequencies much lower than those usually associated with molecular absorption spectra. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 coefficient, or RCS per unit surface area, is much larger for vertical than for horizontal  polarization, with the crosspolar scattering coefficients typically assuming intermedi - ate values for moderate bistatic scattering geometries, s °vv  s °hv ≈ s °vh > s °hh, as  illustrated in Figure 20.10. Eq. 
 BAND 3YNTHETIC !PERTURE 2ADAR 0!,3!2  ABOARD *APANS !,/3 p LAUNCHED  IN *ANUARY   INCLUDES FULL QUADRATUREe POLARIMETRY  4HE 0!,3!2 MODES  INCLUDE STANDARD SINGLE 
 Ruvin and L. Weinberg, “Digital multiple beamforming techniques for radars,” in IEEE  Eascon ’78 Rec. , pp. 
 A Seliga, and K. Aydin, “Hail detection with a differential reflectivity radar,”  Science , vol. 225, pp. 
 Now this is precisely what happened when thevideo bandwidth was made toonarrow, and wemust expect the same consequences. Ineffect, the intensity- modulated cathode-ray tube isalow-pass filter, whose bandwidth isof the order v/d.For example, aradial sweep covering 50miles ofrange cma7-in. PPI tube would bewritten inwith avelocity ofabout 1.5X104 cm/sec. 
 233, 1980. 57. GaAs Solar Cells, Hughes Aircraft Company, presented at Space Power Conf., Los Angeles, Jan. 
 In one example 125 a tilt angle of 27° is taken for a 4-face array  covering from + 90 to -20° in elevation, instead of the 35.3° of Table 8.3. The reduction in  gain is 4.3 dB at the maximum scan angle instead of 2.8 dB.  Dome antenna.126 129 A novel approach to obtaining hemispherical coverage is the dome  antenna depicted in Fig. 
 STATE  TRANSMITTER PROVIDES LOW 
 respectively  a= earth's radius  k = ractor discussed in Sec. 12.4, accounting for refraction due to a uniform gra­ dient of refractivity  The point of tangency of the line of sight with the earth is the geometrical, or optical, lwri:::011.  At optical frequencies () ~ 0) the field strength within the interference region (that is. 
 464–508. Available online: http://iopscience.iop.org /article/10.1086/311945/fulltext/ 985796.text.html (accessed on 24 June 2019). 2. 
 Aluminum honeycomb with aluminum skin in a sandwich construction has been employeci  where highly accurate surfaces are required. Reflector surfaces may also be formed from  fiberglass and asbestos resinated laminates with the reflecting surface made of embedded mesh  or metal spray. Plastic structures have the advantage of being light, rigid, and capable of being  made with highly accurate surfaces. 
 " 
 16.21. .——————————.——.To,I normal Lownoise I receiveramplifier I L—––R:m~eYYl@~: ___~ =S,gnal mixer I gating system——— —— —________ FIQ. 1630.-Block diagram ofatypical MTI receiver: i-f limiting; balanced detector; intermediate frequency 30Mc /8ec; l-p.sec pulBes. 
 POWER PULSES OF ELECTROMAGNETIC  ENERGY INTO THE MATERIAL OR GROUND AND THEN RECEIVES AND DETECTS THE WEAK REFLECTED SIGNAL FROM THE BURIED TARGET 4HE ENERGY IS IN THE FORM OF EITHER A VERY SHORT DURA 
 ING THIS DIFFERENTIAL EFFECT $' P   OVER THE MAIN BEAMS  )'D '4 'PSCAN 
 44, pp. 1146– 1155, September 1956.  7. 
 SEC, 76] THE U.S. TACTICAL AIR COMMANDS237 L___-\\ \\ .——. 238 THE EMPLOYMENT OF RADAR DATA [SEC, 77 saw service inthe European war, but itisbased soundly onmonths of combat experience with improvised and frequently changed systems and devices. 
 47-48  Doppler navigation. 92-95  Doppler-tolerant waveform, 427  Doppler tracking, 182  Double-curvature reflector, 259  Double delay line cancclcr, 109  Double-null diffcrcncc pattern, 175  Double-threshold detector, 388  DPCA, 143- 144  Dual-mode ferrite phase shiiter, 295--296  Ducting, 450--456  Duplexers, 359 366  and diode burnout, 350  Duty cycle, 52  Dynamic programming, 332  Dynamic range, 352  and low-noise receivers, 352  Eagle scanner, 298  ECCM, 542, 547-553  Effective aperture, antena, 226-227  Effective bandwidth, 404-405  Effective earth's radius, 449  Effective noise temperature, 345  Efficiency :  aperture, 228-232  574INDEX Clutter-lock MTI.142 Cluttermap,184 inMTD,127 Coaxial magnetron, 193-198 Coaxitron,213 Codedpulse,428-431 Coherent detector, 385-386 Coherent reference, inMTI,102 Coho,105,141 Cold-cathode emission, 210 Collapsing loss,59-60 ColorCRTs.357 Complex anglemonopulse, 176 Computer controlofarrayradar,322-328 Conesphere1radarcrosssectionof,35-37 Conformal arrays,330-331 Conical scan,155--159, 182-183 Conopulse, 164 Constant-false-alarm-rate receiver(seeCFAR) Constrained feed,306-308 Constrained lens,251 Control electrode, CFA,211 Convective cell,510 Conversion efficiency, 191 Conversion loss,mixer,347 Cookiecuttertuner,199 Corporate feed,285 Correlation detection, 375-376 Correlation function, 373 Correlation time,seaecho,484-485 Cosecant-squared antenna, 55-56,258-261 Cosmicnoise,461 COSRO, 159 Coupled cavityTWT,207 Coverage pattern,elevation, 446-447 Cross-correlation receiver, 375 Crosslevel,antenna, 273 Crosssection(seeradarcrosssection) Crosstalk,intracking radar,158 Crossed-field amplifiers, 208-213 Crossed linearpolarization, 506 Crowbar, fortubeprotection, 216 Crown-of-t hornstuner,199 CRTscreens, 355-357 Cumulative probability ofdetection, 64 CWradar, 6~H~I CWwave-interference radar,9 Datastabilization, antenna, 270 d-coperation, ofCFA,211 Decorrelation time,seaecho,484-485 Decoy,553 Delay-line canceler, 104,106-114 Delaylines,pulsecompression, 424-426Delta-ascanner, 298 Densitymodulation, 213 Density taper,332 Detection criteria, 376-382 withnon-Rayleigh clutter,485-486 Detector characteristics, 382-386 Dickefix,394,549-550 Dielectric lenses,248-250 Diffraction, ~56-459 Digitalphaseshifters, 287-288 Digitalprocessing: MTI,119-125 SAR,526 Diodeburnout, 350 Diodephaseshifters, 288-291 Diodes,microwave, 217 Directive gain,antenna, 224 Dispersive delaylincs,424 426 Displaced PhaseCenterAntenna (DPCA). 143144 Displays, 353 359 definitionsof,354355 Dithertuning,ofmagnetron, 200 Dolph-Chebyshev array,257 Domeantenna, 329-330 Doppler filterbank,MTD.127 Doppler frequency shift,68-69.79-80 inFM-CW radar,83 Doppler measurement accuracy, 407-408 Doppler navigation. 
 However, the pulsing sequence may  use a “dual PRF” mode in which groups of constant PRF pulses are transmitted or  a “dual (staggered) PRT” (pulse repetition time) to resolve both range and velocity  ambiguities.65 Another approach is to employ a transmitted pulse sequence with ran - dom66 or deterministic67 phases from pulse to pulse, which allows overlaid echoes to  be separated. Multiple PRT techniques have also been explored but are not in common  use.68 Range ambiguities cannot be totally eliminated, but their effects can be signifi - cantly mitigated through these approaches. To discuss design details of the common types of meteorological radars is beyond  the scope of this chapter. 
 This is the blip-scan ratio and is the probability of detecting a target at a particular  range. altitude, and aspect. The head-on and tail-on are the two easiest aspects to provide in  field measurements. 
 OFF MAY BE FOUND IN 3ECTION   )N CONTRAST TO CONVENTIONAL POST 
 PLER FILTER WEIGHTS  OR  .K 7 7 7 K . 
 Fabry, S. J. Park, M. 
 266-275, July, 1956.  21. Mathur, P: N., and E. 
 For example, 3-D InISAR imaging method based on sparse constraint model is proposed using the sparsity of ISAR images in reference [ 24]. However, traditional InISAR imaging methods have the following problems: (1) because the observation objectives are consistent, multi-channel echoes in the InISAR system have a strong correlation, i.e., images of each channel have the same target support set. However, in single-channel independent processing, such prior information is not considered, and consistent location and number of scattering points among channel images cannot be ensured, which means it cannot ensure that all scattering points on the target are located in positions with the same pixel in two interferometric images, thus reducing the estimation accuracy of interferometric phase information and (2) in InISAR imaging, scattering characteristics of the target vary with the observation angle, and the imaging azimuth accuracy is limited by scattering anisotropy of the target. 
 Ifthereceived waveform y(t}asafunction oftimeconsists ofthesignal waveform Sj(t}plusthewhitegaussian noisewaveform n(t)=y(e}-Sj(t),Woodward and Davies27showthat p(yISN)=Pn[n(t}]=Pn[y(t}-Sj(t)]exexp[-~~fn2(e)deI wherePn[n(t)]=probability-density function fornoisewaveform n(t)andNo=meannoise powerperunitbandwidth (dimensions ofenergy). Withthissubstitution, theaposteriori probability forthesignalSj(t}becomes {ITO }p(SNIy)=kp(SN)exp-Not[y(t)-Si(tWdt (10.26) Theintegral inthisexpression isadefinite one,withlimitsdefinedbytheduration ofthe observation time(0-.To). Equation (10.26)formsthebasisofthetechnique usedbyWoodward andDaviesforthe analysis ofradarreception problems whentheinterference iscausedbywhitegaussian noise. 
 It can  limit the performance of an MTI radar if sufficient care is not taken in design, construction,  and maintenance.  Consider the effect of phase _variations in an oscillator. If the echo from stationary clutter  on the first pulse is represented PY A cos wt and from the second pulse is A cos (wt + At/>), ' '• where A¢ is the change in oscillator phase between the two, then the difference between the  two after subtraction is A cos wt -A cos (wt+ A¢)= 2A sin (A¢/2) sin (wt + A¢/2). 
 a focused target-image will be obtained. Figure 14.6 shows the basic arrange-  ment of an optical processor. The film contains the superposition of the holographic signals  from all the individual scatterers illuminated by the radar. 
 NEOUS FREQUENCY OVER THE PULSE IN &IGURE . 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 17 .32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 We now consider | d  (∆f)| = the change in ∆f  due to a change in h given by | d  h|:  | ( )| | | δ φπ λδ ∆ =2nL Rh 17.57) Antennas A and B may be considered as separated in vertical distance on an aircraft. 
 ch17.indd   37 12/17/07   6:50:14 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 
 62. W. D. 
 Repeater jamming. A target under observation by a radar can generate false echoes by delay­ ing the received radar signals and retransmitting at a slightly later time. This is accomplished  in a rq1earcr Jammer. 
 9.6.—Afanbeam which enables anairborne radar toscan thesurface oftheearth. FIG.9.7.—The energy distribution toasquare.root scale asafunction ofthedepree+sion angle inanairborne n~vigational radar, flying atany constant altitude will beindicated with aconstant intensity, independent ofrange. Several antenna types have been developed forproducing acosecant- squarecf fan beam; those most widely used can bediscussed interms of. 
 XI Formerly ASV.X, a forward-looking 3 cm radar used in Swordfish aircraft of FAA. ASV Mk. XII Modified AI Mk. 
 MODE AND SCAN3!2 PROCESSING v  )%%%  4RANSACTIONS ON 'EOSCIENCE AND 2EMOTE 3ENSING  VOL   PP n    + 4OMIYASU  h#ONCEPTUAL PERFORMANCE OF A SATELLITE 
 Army that fought inEurope was accompanied byaTactical Air Command whose mission was that ofproviding airdefense intheforward sector occupied bytheArmy concerned, ofconducting offensive operations against enemy ground troops and installations inthe immediate tactical area, and of conducting offensive operations inclose cooperation with friendly ground units. The aircraft ofaTactical Air Command, orTAC, were almost entirely fighters and fighter-bombers. Each TAC went into thefighting ontheContinent with aradar organization ofthegeneral character shown — Control ——–— Reporting m ~_––—– I 1 I1 FDP“A”FDP“C”FDP“B’ —Type15,TyPe11, Type 15,Type 11, 1 I I I SCR-5S4 SCR- 564 SCR-584 I I I I I II 1 III I1I Alternate Alternate ! Alternate NCS+ NCS NCS‘;%NCS $NCS=;NCS 0“>1J cf’’d’~ U’”’d i Groundobserver posts Groundobserver posts Groundobserver posts FKG.7.10.—Fighter controlsystemofIXTactical AirCommand. 
 FREQUENCY NOISE CAN CAUSE THE AMPLITUDE AT THE TWO BEAM POSITIONS TO DIFFER  THUS CAUSING AN ERRONEOUS INDICATION THAT THE  TARGET IS OFF AXIS 4HIS EFFECT IS AVERAGED  OUT EXCEPT FOR THE NOISE SPECTRAL ENERGY NEAR THE SCAN RATE &OR EXAMPLE  A PERIODIC MODULATION SPIKE NEAR THE SCAN RATE WILL CAUSE THE TRACKING RADAR TO DRIVE ITS ANTENNA IN A CIRCULAR MOTION AROUND THE TARGET AT A RATE EQUAL TO THE DIFFERENCE IN FREQUENCY BETWEEN THE SCAN RATE AND THE FREQUENCY OF THE SPECTRAL LINE 4HE DIRECTION  CLOCKWISE OR COUNTERCLOCKWISE  DEPENDS UPON WHETHER THE SPECTRAL LINE IS ABOVE OR BELOW THE SCAN RATE AND WHETHER THE SCAN IS CLOCKWISE OR COUNTERCLOCKWISE 4HE SERVOSYSTEM FILTERS OUT ALL FREQUENCIES OUTSIDE THE FREQUENCY RANGE BETWEEN THE SCAN RATE PLUS THE SERVO BANDWIDTH AND THE SCAN RATE MINUS THE SERVO BANDWIDTH  AND AN ANGLE SENSITIVITY CONSTANT THAT CONVERTS RMS MODULATION TO RMS ANGLE ERROR !N EQUATION USING THIS RELATION TO CALCULATE RMS NOISE IN SCANNING AND LOBING 
 ECHO SPECTRA v  2ADIO  3CIENCE  VOL    NO   P      4 - 'EORGES  * ! (ARLAN  2 2 ,EBEN  AND 2 ! ,EMATTA  h! TEST OF OCEAN SURFACE CUR 
 OGY IS FOR THE BEAMFORMING FUNCTION IN A PHASED ARRAY ANTENNA SYSTEM &IGURE  A  DEPICTS AN ANALOG BEAMFORMING SYSTEM 4HE WAVEFRONT SHOWN CAN BE THOUGHT OF AS THE  RETURN FROM A TARGET OF INTEREST .OTE THAT THE WAVEFRONT WILL HIT EACH ELEMENT OF THE ARRAY AT DIFFERENT TIMES )N ORDER TO FORM A BEAM IN THAT PARTICULAR DIRECTION  EACH ELEMENT OF THE ARRAY NEEDS TO BE FOLLOWED BY A TIME DELAY UNIT THAT DELAYS THE SIGNAL RECEIVED AT EACH ELEMENT BY THE APPROPRIATE AMOUNT  SUCH THAT WHEN ALL OF THE OUTPUTS OF THE TIME DELAYS ARE SUMMED  THEY ADD UP COHERENTLY TO FORM A BEAM IN THE DESIRED DIRECTION )F THE SYSTEM HAS A NARROW BANDWIDTH BANDWIDTH   ^ OF 2& FREQUENCY  AND THE ANTENNA BEAMWIDTH IS NOT TOO NARROW SO THAT THE  D" BEAMWIDTH IN DEGREES IS GREATER  THAN THE PERCENT BANDWIDTH   THE TIME DELAY CAN BE APPROXIMATED USING PHASE SHIFTERS  7IDE BANDWIDTH SYSTEMS REQUIRE hTRUEv TIME DELAYS IN ORDER TO FORM THE BEAMS AND PRESERVE THE BANDWIDTH 4HE RECEIVER WOULD FOLLOW THE ANALOG BEAMFORMER  AS SHOWN IN THE FIGURE &IGURE  B SHOWS AN EXTREME APPLICATION  OF DIGITAL BEAMFORMING  WHERE  &)'52%   A  !NALOG BEAMFORMER  B   EVERY 
 Passive modes  are interleaved with active operation to improve survivability and passive tracking and  ID. Each mode shown in Figure 5.13 is optimized in real time for the particular combi - nation of altitude, range to the target, density of target threats, antenna footprint on the  Earth’s surface, relative target and clutter doppler, dwell time available, predicted target  statistical behavior, transmitted frequency, and desired resolution.9,11 The mode category “autonomous and cued search” contains the modes most com - monly associated with fighter radars. There are usually two range-gated high pulse rep - etition frequency (HPRF) modes: velocity search (VS) primarily dedicated to longest  range detection and range while search (RWS), which uses some form of FM ranging  to estimate target range. 
 1960.  58. Beckmann, P.. 
 MODULATION INVOLVES NONLINEAR MIXING OF A STRONG  INTERFERER WITH THE RECEIVED RADAR ECHOES  TRANSFERRING THE INTERFERER MODULATION ONTO THE RADAR SIGNAL   )N 
 In principle the parabolic torus can be scanned 180°, but because of beam spillover near  the end of the scan and self-blocking by the opposite edge of the reflector, the maximum scan  angle is usually limited to the vicinity of 120".  Only a portion of the parabolic-torus is illuminated by the feed at any particular time.  This may appear to result in low aperture utilization or poor efficiency since the total physical  area is not related in a simple manner.to the gain as it is in a fully illuminated antenna. 
 POLAR HORIZONTAL REFLECTIVITY  :CO H  "ECAUSE POLARIMETRIC MEASUREMENTS ADD NEW  DIMENSIONS OF RADAR INFORMATION AND BECAUSE THESE MEASUREMENTS ARE RELATED TO THE PHYSICAL CHARACTERISTICS OF THE SCATTERERS  SUITABLE COMBINATIONS OF THESE DATA GIVE A STRONG INDICATION OF PRECIPITATION TYPE RAIN  SNOW  ICE PARTICLES  SLEET  HAIL  ETC    AS  WELL AS RADAR ECHO CLASSIFICATION INTO VARIOUS CATEGORIES PRECIPITATION  GROUND OR SEA CLUTTER  BIRDS AND INSECTS  CHAFF  ETC   2ADAR #ALIBRATION  4O EFFECTIVELY USE RADARS FOR ACCURATE PRECIPITATION ESTI 
 The  minimum frequency shift is equal to the reciprocal of the pulse width. Slow tuning rates can be  used. but the pulse-to-pulse frequency might not appear random. 
 The classical radar range equation (Chap. 2) shows that  the transmitter power depends on the fourth power of the radar range. To double the range of  a radar, the power has to be increased 16-fold. 
 HONORED WIDE 
 It can be seen that the basic MAM method only compensates the spatially-invariant Doppler phases and hence can be only applied for the broadside or small-squint cases. Although the IMAM methods have partly overcome this disadvantage by estimating and compensating the spatial reliance of the Doppler phase up to the second-order, they still suffer from the problem of insufﬁcient accuracy for the VHS SAR imaging. In this study, this problem is solved by further estimating and compensating the spatial variance of the third-order Doppler phase, resulting in the new EMAM method. 
 The  phase and amplitude of each pulse echo is digitally recorded by the radar. As shown  in Figure 17.1 a, a discrete Fourier transform (DFT)—typically a fast-Fourier trans - form (FFT)27—is applied to this set of N complex samples of frequency-domain data,  resulting in a set of N complex numbers in the time-domain corresponding to echoes  (magnitude and phase) that would be returned from a very short pulse of width ≈ 1/B,  sampled at time intervals ∆t = 1/B. This is a simple example of pulse compression. 
 The field distribution is then used to compute the far- field radiation pattern. For more complex geometries, e.g., offset-fed reflectors, this  method does not work as well as the more rigorous physical optics (PO) method that  is described in Section 12.4. For the simple center-fed focal feed example shown in Figure 12.1, the simpler  aperture-field method of analysis is accurate and its application is simple and straight - forward and makes the discussion of the radiation losses easier to follow. 
 If n pulses, all of the same signal-to-noise ratio, were integrated by an ideal predetection  integrator, the resultant, or integrated, signal-to-noise (power) ratio would be exactly n times  that of a single pulse. If the same ff pulses were integrated by an ideal postdetection device, the  resultant signal-to-noise ratio would be less than n times that of a single pulse. This loss in  integration efficiency is caused by the nonlinear action of the second detector, which converts  some of the signal energy to noise energy in the rectification process. 
 5.2–5.7.   2. A. 
 PLEXITY OF A POLARIZATION 
 The low-angle technique avoids this problem by using a pair of squinted beams on receive, as illustrated in Fig. 20.12. The lower beam, unweighted so as to generate as narrow a beam as permitted by the array aperture, is placed in elevation so that the indirect path is attenuated by the lower side of the beam. 
 It might also be mentioned that the magnetron has had outstanding success as the  power source for the microwave oven. Over the years, it has developed into a very  low cost and highly reliable generator of microwave power that is well-suited for this  application. 10.4 CROSSED-FIELD AMPLIFIERS28 The crossed-field amplifier, or CFA, like the magnetron, has a magnetic field that is  orthogonal to the electric field, but it is an amplifier rather than an oscillator.29 It is  similar in appearance to a magnetron except that the RF circuit is interrupted to pro - vide the input and output connections as needed for an amplifier. 
 [ CrossRef ] 24. Yang, L.; Xing, M.; Zhang, L.; Sheng, J.; Bao, Z. Entropy-based motion error correction for high-resolution spotlight SAR imagery. 
       
 ENCE  ARE INDEPENDENT SAMPLES FROM AN UNKNOWN DENSITY FUNCTION  THE RANK OF THE TEST SAMPLE IS UNIFORM AND CONSEQUENTLY  A THRESHOLD THAT YIELDS #&!2 CAN BE SET #LUTTER MAPS STORE AN AVERAGE BACKGROUND LEVEL FOR EACH RANGE 
 1661-1701, December, 1974.  27. Dionne, G. 
 Therefore, the monopulse opera - tion will also not be disturbed.102 Phased-Array Radars .  In this subsection, we illustrate, by a numerical exam - ple, the role played by the scheduler in a multifunctional PAR to combat ECM. To this  end, we resort to a benchmark study described in the literature, which defines typical  ECM threats, operational scenarios, and phased-array performance mainly in terms   of target tracking under ECM. 
 Parallax errors aremade assmall aspossible byplacing the scale very close tothe tube face, and inmany cases by ruling onboth sides ofarather thick transparency inorder toprovide a line ofsight. Movable angle indices ofthesame type arelittle used except inthe important case ofthe centered PPI, where the motion isone ofsimple rotation. The index or“cursor” may consist ofathin metal strip viewed edgewise orofatransparency with aruled line orathin slit milled through it. 
 Boyer, W. D.: A Diplex, Doppler Phase Comparison Radar, IEEE Trans., vol. ANE-10, pp. 
 Multiple-Target F-m Range Measurement.—In the absence of clutter and doppler shift almost the same methods can beused with a plurality oftargets aswith asingle target. Inthis case linear frequency variation with time isalmost essential, and the triangular form ofFig. 5.12 isprobably most convenient, though asaw-tooth variation might beused. 
 Inthecase ofconical scanning, the output voltages ofthis generator are direct measures ofthe sine and cosine ofthe phase ofthe scan. Inthe spiral scan, the voltages are modulated interms ofthe nod angle, either byvarying the generator field current byapotentiometer onthe nod shaft, orbypassing each sinusoidal voltage through such apotentiometer after generation. The signals thus produced can beused directly inthesynthesis oftype Band type Cdisplays. 
 Range alignment and phase compensation are also referred to as autofocusing. Due to imperfection of coarse compensation, this paper focuses on phase compensation. Methods for phase compensation may be divided into three categories. 
 ING THE OBSERVER FROM SMOOTH SURFACES SUCH AS WATER IS THAT FROM FACETS FOR WHICH ANGLE OF INCIDENCE EQUALS ANGLE OF REFLECTION 4HUS  THE OBSERVED LIGHT MAY BE DESCRIBED BY METHODS OF GEOMETRIC OPTICS 7HEN GEOMETRIC OPTICS IS USED TO DESCRIBE RADAR SCATTER  THE SURFACE OF THE GROUND  IS REPRESENTED BY SMALL FLAT 
 An exact evaluation can be performed for a circular cyl- inder and a spherical cap viewed along the axis of symmetry, but not for a trun- cated cone or a spherical cap seen along other than the axis of symmetry. Even so, the exact evaluation for the cylinder includes fictitious contributions from the shadow boundaries at the sides of the cylinder that do not appear in a stationary phase approximation.32 The amplitude of the elemental surface patch contributions changes slowly over the surface of integration while the phase changes much more rapidly. As such, the net contribution in regions of rapid phase change is essentially zero and may be ignored. 
 Since ( ∆fd)b > (∆fd)m, the constraint on bistatic signal processing time is  slightly less than the equivalent monostatic time. As in the monostatic equation, the transmitting and receiving pattern propagation  factors, FT and FR, each consist of two terms: the propagation factors, F'T and F'R,  and the antenna pattern factors, fT and fR, respectively. The antenna pattern factors are  the relative strength of the free-space field radiated by the transmitting and receiving  antennas as a function of their pointing angles. 
 The  power levels of these third order intermodulation products are given by  P dBm P dBm P dBm P d Bmf f f f 2 1 2 1 2 2 2− = + − ( ) ( ) ( ) ( )IP (6.1)  P dBm P dBm P dBm P d Bmf f f f 2 2 1 1 22 2− = + − ( ) ( ) ( ) ( )IP (6.2) where Pf 1(dBm) = power of input signal at frequency f1 in dBm  Pf 2(dBm) = power of input signal at frequency f2 in dBm  PIP(dBm) = third order intercept point in dBm Intermodulation can result in a variety of undesirable effects such as ● Intermodulation of clutter returns causing broadening of clutter doppler width,  resulting in the masking of targets ● Unwanted in-band signals due to out-of-band interfering signals, resulting in  false targets ● Intermodulation products from in-band signals that cannot be readily cancelled  through linear cancellation techniques, resulting in susceptibility to jammers Intermodulation distortion occurs throughout the receiver chain. Consequently, the  receiver will have a significantly different input intercept point, depending on the  signal frequency relative to the radio frequency (RF), IF, and video filter bandwidths.  It is, therefore, important to distinguish between the requirements for in-band and  out-of-band intermodulation distortion as different signals have different effects on  the receiver. 
  %  "(%   %  "% %  "% %  "(%      '! $  $(  
 W.: The Attenuation and Radar Echoes Produced at Centimetre Wavelengths by Various Meteorological Phenomena, in "Meteorological Factors in Radio Wave Propagation," Physical Society, London, 1946, pp. 169-188. 24. 
 70. Caspers, J. W.: Automatic Detection Theory, chap. 
 R. Goldstein and C. Werner, “Radar interferogram filtering for geophysical applications,”  Geophysical Res. 
 Figure 4.24 Improvement factor for each filter of an 8-pulse doppler filter bank with uniform weighting as  a function of the clutter spectral width (standard deviation). The average improvement for all filters is  indicated by the dotted curve. (From ~ndrews.~')  0 0.001 0.01  Clutter spectral width /radar prf  Figure 4.25 Improvement factor for an N-pulse delay-line canceler with optimum weights (solid curves)  and binomial weights (dashed curves), as a function of the clutter spectral width. 
 fewer cams onahigher-speed shaft can beused. The latter method ispreferable because ofthecleaner action, 2.Figure 1333 illustrates amethod forgenerating angle marks by using aphotocell mounted behind aslotted rotating disk. Since theslots can bemade extremely narrow and noinertia isinvolved, this method produces extremely clean-cut markers. 
 ALIGNED IRREGULARI 
 Schrank, “Low sidelobes phased-array and reflectors antennas,” in Aspects of Modern  Radar , E. Brookner (ed.), Norwood, MA: Artech House, Inc., 1988. 33. 
 28. L. V. 
 ASPECT 3EARCH WAVEFORMS INCLUDE  6ELOCITY 3EARCH 63   (IGH 
 The former is sometimes called the directivity, while the latter  is often simply called the gain. Both definitions are of interest to the radar systems engineer.  The directive gain is descriptive of the antenna pattern, but the power gain is more appropriate  for use in the radar equation. 
 TERM FORECASTING v  * !PPL -ETEORO     VOL   PP n    - (ALL ED   h3PECIAL PAPERS -ULTIPLE PARAMETER RADAR MEASUREMENTS OF PRECIPITATION v  2ADIO  3CI  VOL     2 - ,HERMITTE  h$UAL 
 The digital processor, however, does not experience degradation due to time jitter of  the transmitted pulse since the system clock controlling the processor timing may be started  from the detected rf envelope of the transmitted pulse.  Internal fluctuation of clutter. 48 Although clutter targets such as buildings, water towers, bare  hills. 
 4, pp. l 7-32, 1975.  50. 
 12.6 DIFFRACTION  In free space, electromagnetic waves travel in straight lines. In the earth's atmosphere, radar  waves can propagate beyond the geometrical horizon by refraction. Another mechanism that  permits radar coverage to be extended beyond the geometrical horizon is ditf'ractio11. 
   PP n    2 "ERNARD AND $ 6IDAL 
 SHOULDER GEOMETRY AND THE  TRANSMITTER OPERATING ON A SATELLITE WITH THE RECEIVER AND TARGET NEAR THE EARTH 4HE ERROR IN %Q  IS LESS THAN  PERCENT FOR  n  P 2   n AND ,    24   22  OR  C$4RT  4HE ERROR GROWS RAPIDLY FOR P2   n /THER TARGET LOCATION TECHNIQUES ARE POSSIBLE    n &OR EXAMPLE  WHEN A  BISTATIC HITCHHIKER EXPLOITS THE TRANSMITTER OF A MONOSTATIC RADAR  THE RADARS LOOK ANGLE P 4 CAN BE USED IN PLACE OF OR IN CONJUNCTION WITH  P2 !N EXAMPLE OF THE LATTER IS THE  THETA 
 CORRELATION FUNCTIONS OF  
 initiation ofcathode emission over awide range ofanode voltage. The anode ofahydrogen thyratron iscompletely shielded from the cathode bythegrid. The effective grid action results invery smooth firing over awide range ofanode voltages and repetition frequencies. 
 Delaney, W. P.: An RF Multiple Beam-Forming Technique. IRE Tvrrtis.. 
 Huygens' principle may be applied in the far field by dividing the plane  wave across the circular aperture into a great many spherical wavelets, all or the same phase  but of different amplitude. To find the field intensity at a point a distance R from the antenna,  the amplitudes of all the waves are added at the point, taking account or the proper phase  relationships due to the difference in path lengths. The field intensity at a distance R is thus  proportional to  2,r ro ( 2n:R) E(R) = ( dO ( A(r, 0) exp jT r dr (7.18)  where r0 is the radius of the aperture. 
 Radar Conf ., Arlington (V A), USA, May 7–10, 1990, pp. 444–450. 108. 
 ,Ê, ,- -4) FILTERS ARE USED AT THE LOWER ELEVATION ANGLES IN WEATHER RADARS TO PREVENT WEATHER ESTIMATES FROM BEING CONTAMINATED WITH GROUND CLUTTER RETURNS )T IS  HOWEVER  ALSO VERY IMPORTANT TO PRESERVE AN ACCURATE MEASUREMENT OF WEATHER INTENSITY AND PRECIPI 
 160 TYPES OFRADABIN~ICATOW. 161 6.2 Definitions ........ 161 6.3 Summary ofIndicator Types 163 6.4 One-dimensional Deflection-modulated Displays. 
 With the large developments in GPU, the layers of CNNs had become much deeper. In recent years, many new models had been proposed, such as Alexnet [ 24], Resnet [ 34], VGG16 [ 22], etc. In this paper, we mainly use two different models for ship classiﬁcation in order to do comparative test. 
 P.:Low-Cost Processing andDisplay SystemforRadarTracking andIntercept, IEEE EASCON '75Conl1ention Record,pp.108-Ato108G,1975. 37.Reintjes, J.F.,andG.T.Coate:" Principles ofRadar,"3ded.,chap.12,McGraw-Hill BookCompany, NewYork,1952. 38.Riblet,H.J.:TheShort-Slot HybridJunction, Proc,IRE,vol.40,pp.180-184, February, 1952. 
 Their two phased array slotted waveguide  antennas are sized and oriented so that their footprints are the same. Their respective  steered beams are synchronized so that for the central 100-km swath within which they  both have coverage, their vertical profiles are near-simultaneous. The KuPR and KaPR  antennas are sized at 2.4 m × 2.4 m and 1.4 m × 1.0 m, respectively, each comprised  of 148 slotted waveguides driven by individual solid-state power amplifiers. 
 I. Skolnik, “An analysis of bistatic radar,” IRE Trans ., vol. ANE-8, pp. 
 7.28. The error current in one region of the antenna is assumed independ-  ent of the error currents in adjacent regions. The size of the regions in which the error  currents cannot be considered independent is the correlation interval, C. 
 L V.: Ray Hei~ht Computation for a Continuous Nonlinear Atmospheric Refractive-Index  Profile. Radio Science. vol. 
 RADIUS MODELS ARE OF THE SAME NATURE  THEY DO NOT  IMPLEMENT THE VARIOUS PROPAGATION MECHANISMS EQUALLY &OR EXAMPLE  THE  & 
 oX X Y YDP DQ    P  Q             4HE  LOBE AT P   Q    IS THE MAIN BEAM ! TRIANGULAR GRID IS MORE EFFICIENT FOR  SUPPRESSING GRATING LOBES THAN A RECTANGULAR GRID  SO THAT FOR A GIVEN APERTURE SIZE  . 
 In principle, a single antenna may be  erliployed since tlie necessary isolation between the transmitted and the received signals is  acliieved via separation in frequency as a result of the doppler effect. In practice, it is riot  possible to eliminate completely the transmitter leakage. However, transmitter leakage is not  always undesirable. 
 Sidelobe Discretes. An inherent characteristic of airborne pulse doppler radars is that echoes from large objects on the ground (discretes), such as buildings, may be received through the antenna sidelobes and appear as though they were smaller moving targets in the main beam. This is a particularly severe problem in a medium-PRF radar, where all-aspect target performance is usually desired, as these returns compete with targets of interest. 
 The decoy diverges from  the velocity vector of the launch aircraft by natural deceleration as a result of air stream  and falling due to gravity. The decoy typically starts radiating jamming signals toward  the missile seeker immediately after ejection from the aircraft and continues radiation  throughout its flight. Decoy ejection is typically commenced when the RWR detects  incoming radar-guided missiles. 
 and D. J. Harris: Submillimeter Waves. 
 BACK RATIOS )N THE ELEVATION PLANE  DESIRABLE RADIATION ANGLES RUN BETWEEN  n AND n FOR COM 
 The hydrogen thyratron, unlike most thyratrons, has apositive grid-control charac- teristic, and hydrogen filling isused toreduce deionization time and make theperformance ofthetube independent ofambient temperature. This independence ismaintained with the exception that the average dissipa- tion rating ofthetube canbelowered byexcessively high airtemperature.. :.10.10. 
   &*#%*  (*!&%!% !) ( *  , # '+!( $ %*                  &)'52%  $YNAMIC RANGE AND STABILITY LEVELS. {°Ón  2!$!2 (!.$"//+  GAUSSIAN NOISE  THE LATTER TERM ARISING FROM THE GAUSSIAN STATISTICS OF ITS VOLTAGE PROB 
 Is the two-sided bandwidth always twice the one-sided bandwidth? For complex  signals in general, no, but for real signals in particular, yes. Here’s why: any signal,  real or complex, when expressed as a Fourier integral (inverse Fourier transform) is FIGURE 25.1  Typical radar receiver front-end design from 1990LPF LPFIF2ADC ADCQIANALOG   DIGITAL N N QI PC LO2IF1 LO1RF  INTO BACKEND  PROCESSING90°LO4 BPF BPFIF3 LO3BPFSAMPLE  CLOCK FIGURE 25.2  Typical digital receiver front endIF2 LO2IF1 LO1RF  INBPF BPFDIGITAL  PC SAMPLE  CLOCKNTO BACKEND  PROCESSINGANALOG    DIGITAL QI DDCI QADC ch25.indd   2 12/20/07   1:39:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 D., and J. M. Smith: Multi-Frequency Complex-Angle Tracking of Low-Level Targets,  Radar-Present and Future, pp. 
 The all-pass, time  delay using bridged-T networks with either lumped-constant circuit elements or stripline; the  waveguide operated near its cutoff frequency; and the tapered folded-tape meander line are  examples of electromagnetic dispersive delay lines suitable for linear-FM pulse compression.  The charge-coupled device has also been considered for application in pulse compression. 19  Each of these delays lines has different characteristics and preferred regions of operation as  regards bandwidth and pulse duration.16 Only the surface acoustic wave (SAW) device will be  described here as an illustration of a typical dispersive delay line suitable for radar applicati0n.10  The surface-acoustic-wave delay line, shown schematically in Fig. 
 Note that for this analysis to be correct the MTI velocity response must be scaled to have O dB gain to noise, not to an op- timum doppler frequency. Integration of Residue Power. The MTI improvement factor limitation of the stalo may be expressed as the ratio of the stalo power to the total power of the echo modulation spectrum it creates at the output of the cascaded filters (Figs. 
 Theseare n~ /ls=1.388 n~ 12s=3.853(singlecanceler) (double canceler)(4.34) (4.35) TheseareplottedinFig.4.31. Astepped-scan antenna thatdwellsataparticular regioninspace,ratherthanscan continuously, alsoislimitedinMTIperformance bythefinitetimeontargetto.Thetime waveform isconstant sothatitwillhaveadifferent spectralshapeandadifferent improvement factorthanthatproduced bythegaussian beamassumed intheabove. Limiting inMTIradar.8.53-55 Alimiterisusuallyemployed intheIFamplifier justbeforethe MTIprocessor toprevent theresiduefrom large clutterechoesfromsaturating thedisplay..._»'f IdeallyanMTIradarshouldreducethecluttertoalevelcomparable torece.iver noise. 
 4Pulse length, ~ec 0.8 2,2 025 05 2.6 52 1 1PRF, 13pS 840 420 1600 800 4oil 200 1000 800Power 25kw 25kw 250kw 250kw 250kw 250kw 250kw 33fw- Animportant design consideration inpulse network applications is the average power tobehandled. Apulse network designed tohave adequate lifeatone pulse rate would overheat and perhaps beruined by operation atahigher repetition frequency. Since overheating isafunc- tion ofboth applied voltage and repetition rate, little flexibility remains inaline-type pulser designed toachieve maximum economy ofweight, space, and power. 
 This is the principle behind  the ScanSAR mode. Ambiguity Space Trade-offs.  It is easy to show that these resolution and coverage  options are consistent with the principles that govern range and azimuth ambiguities. 
    !           "     !!  
 58. Graf, W., R. N. 
 If the 2n radians is changed in a time 1/fs, then the  rate of change of phase is 2nf,. Thus the linear phase change can be accomplished if  the rrequency <lilTerence between the LOs at the mixers of adjacent elements is fs.  By multiplying the summed output of all the element mixers with a periodic sampling  train of narrow gating pulses, a particular portion of space is observed. 
 The maximum efficiency of the single-tuned filter occurs for Br ;::::: OA. The correspond­ ing loss in signal-to~noise ratio is 0.88 dB as compared with a matched filter. Table 10. 
 IIIC Squadrons with Sunderland Mk. III; ASV Mk. VI 3 Wellington squadrons;ASV Mk. 
 This upper limit generally  applies to large ships and frequencies in the lower HF band.176,177 ECM to OTH Radar.  For both skywave and surface-wave OTH radar systems,  the ionosphere also propagates unwanted interference signals to the radar site, par - ticularly at night when the ionosphere is prone to propagating radio frequency inter - ference (RFI) sources from very long distances. RFI can arise from unintentional and  intentional anthropogenic emitters in the user-congested HF band, as well as jamming  sources. 
 Basic of Scintillation Simulator The scintillation simulator proposed by Carrano [ 27] is based on the phase screen theory and has been widely acknowledged. The phase screen theory assumes that the turbulent irregularities are constrained within a very thin layer. Therefore, the ray-bending and multi-scattering effect can be neglected within the layer. 
 Series-parallel or series-series arrangements are also possible.) All the elements which  lie in the same column utilize the same phase shift to steer the beam in azimuth. Likewise all  the elements which lie in the same row utilize the same phase shift to steer the beam in  elevation. The phase shift at the 11111th element therefore is the sum of the phases required at the  111th column for steering in azimuth and at the 11th row for steering in elevation. 
 MI INTERVALS   &)'52%   %FFECT OF LIMITERS  A   D" IMPROVEMENT FACTOR   D" INPUT DYNAMIC RANGE  AND   B   D" IMPROVEMENT FACTOR   D" INPUT DYNAMIC RANGE . Ó°Èä  2!$!2 (!.$"//+  ! NUMBER OF BIRDS ARE SHOWN ON THE DISPLAY 4HE RESIDUE FROM CLUTTER IN THE LEFT PHOTO 
 Develop ., pp. 478–484, September 1970. 26. 
 Day. W. R .. 
 lligher frequencies can provide the same angular beamwidths with smaller antennas, but the  smaller apertures must be compensated by greater power if the maximum ranges are the same.  Although high-power transmitters are available at S band, the peak power that can he  transmitted is less because of the smaller waveguide sizes. Pulse compression can be used tu  compensate for the reduced peak power, but at the price of additional complexity. 
 AES–41, no. 3, pp. 1082–1090, July 2005. 
 43. Johnson. R. 
 DETECTOR SENSITIVITY MAXIMUM VALUE OF  FOR A RECEIVER  WHERE "      3.   SIGNAL 
 BASED DUCTS IS THE SKIP ZONE NEAR THE NORMAL  HORIZON  IN WHICH THE DUCT HAS NO INFLUENCE )T SHOULD BE NOTED THAT THE SURFACE DUCT CRE 
 McKee: Wind Loads on Antenna Systems, Microwuur J., vol. 7, pp. 41 -46,  September, 1964. 
 Any use is subject to the Terms of Use as given at the website. Airborne MTI.  AIRBORNE MTI  3.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 abeam, the predominant effect is the velocity spread across the antenna beamwidth. These  are classified as the slant-range effect and the platform-motion effect, respectively. 
 or the  shadow. region. Here radar signals are rapidly attenuated. 
 At around 2 km horizontal  distance, some internal scattering from the glacier is seen. This is scattering from the  free water inside the glacier. From 4 km to 5 km, the bottom echo is difficult to see  due to scattering. 
 When the detection of the radar signal is limited by an external noise source, such as a deliberate noise jammer rather than by receiver noise, the parameters of importance in determining range performance are slightly different from those presented above (Chap. 9). The receiver noise power per unit bandwidth is now that determined by the jammer rather than the receiver noise figure. 
 If such antennas are used with time-domain radar, the dispersive properties of the  antenna used must be compensated by suitable post-processing filtering. The time-domain radar system transmits a sequence of pulses, typically of ampli - tudes within the range between 20 V to 200 V and pulse widths within the range  between 200 ps to 50 ns at a pulse repetition interval of between several hundred  microseconds to one microsecond, depending on the system design. The impulse  generator is generally based on the technique of rapid discharge of the stored energy  in a short transmission line. 
 TIONS REQUIRED WITH EMPHASIS ON REDUCING THE NUMBER OF MULTIPLICATIONS  AS THESE REQUIRE SIGNIFICANTLY MORE RESOURCES THAN ADDITIONS 4WO TECHNIQUES USED TO REDUCE THE &)2 FILTER PROCESSING BURDEN ARE MULTIRATE PROCESSING AND POLYPHASE FILTERING   4HE DIGITAL DOWNCONVERSION APPROACH IS SHOWN IN &IGURE  USING MULTIRATE PRO 
 BIT  SEQUENCES AND B    
 1 I. 1%.  This is a Barker code of length 13. 
 QUALITY ABSORBING MATERIAL 4HE LOWER THE INTENDED FREQUENCY OF OPERATION  THE  MORE EXPENSIVE THE ABSORBER BECOMES !BSORBER  REFLECTIVITY RATINGS OF  
 Ofcourse there aremany possible types ofmodulation besicfcs simple AM and FM but these will not be treated here. 5.3. Effect ofTarget.—The effect ofreflection from the target onthis spectrum will now beconsidered. 
 #7  SIGNAL /FTEN  THERE IS SOME PROVISION FOR AMPLITUDE SHAPING  NORMALLY AT THE COMMENCEMENT AND END OF EACH SWEEP 4HE *INDALEE RADAR WAS DESIGNED WITH THE FACILITY TO APPLY A NUM 
 Thus the antenna pattern must be  accurately known and taken into account in the data analysis. A pattern with strong  minor lobes may be simply inadmissible. The scattering coefficient is determined by applying  PP G dA Rrt t= ∫λ πσ2 32 0 44( )Illuminated area  The integration is over whatever area is illuminated significantly, including the regions  hit by the minor lobes. 
   05,3% $/00,%2 2!$!2   {°ÓÎ &)'52%  3INGLE 
 ' 103.Giaccari, E.,andG.Nucci:AFamilyofAirTrafficControl Radars,IEEETrans.,raJ.AES-J5, pp.378:396, May,1979., . 104.Wickenden, B.V.A.,andW.G.Howell: FerriteQuarter WaveTypeAbsorber, Conference Proceed­ ingsMilitaryMicrowave, London, 1978,Microwave Exhibitions andPublishers Ltd.,pp.310--317. 105.Bachman, C.G.:..LaserRadarSystems andTechniques," ArtechHouse,Inc.,Dedham, Ma,1979.. 
 The first use of electromagnetic signals to determine the presence of remote terres - trial metal objects is generally attributed to Hülsmeyer in 1904, but the first description  of their use for location of buried objects appeared six years later in a German patent  by Leimbach and Löwy. The work of Hülsenbeck in 1926 appears to be the first use  of pulsed techniques to determine the structure of buried features. He noted that any  Radar Processor and Display Battery Housing forTransmitter—Receiverand Antennas FIGURE 21.1  Typical GPR system ( Courtesy US Radar ) FIGURE 21.2  Typical display from GPR ch21.indd   2 12/17/07   2:51:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Sensors 2019 ,19, 516. [ CrossRef ][PubMed ] 13. Zhang, Y.; Liu, Y.; Jin, M.; Jing, Y.; Liu, Y.; Liu, Y.; Sun, W.; Wei, J.; Chen, Y. 
 G .. and J. Wild: Present and Future Radar Display Techniques, International Co11f. 
 ...PDI PDIPDI3.2 
 Rain gauge measurements are frequently  used to adjust the radar reflectivity values.115 Zawadzki116 describes many factors that  influence rainfall measurement by radar. Joss and Lee117and others118,119,120 use the  Vertical Profile of Reflectivity (VPR) to estimate the surface rainfall rate with some  success. Bridges and Feldman121 discuss how two independent measurements (reflec - tivity factor and attenuation) can be used to obtain both parameters of the drop-size  distribution and more precisely determine the rainfall rate. 
 III antenna would have increased the clutter return by about Table 7.5. Radar parameters. Parameter ASV Mk. 
 The actual implementation must be based on the  parameters of the system and permissible time allocated for each dwell. The PRFs of the CPIs should be selected to minimize the chance of false radial  velocity determinations. One method of selecting PRFs is similar to selecting pulse  interval ratios for staggered PRF operation, as described in Section 2.8. 
 thc otherbeingthescattered pathwhichincludes thetarget.Themeasurements whichcanbe madeatthebistatic receiver are: l.Thetotalpathlength(Dr+Dr).01'transittime,ofthescattcred signal. 2.Theangleofarrivalofthescattered signal. J.Thefrequcncy ofthedirectandthescattcred signals.Thesewillbedifferent ifthetargetisin motion(doppler cffect). 
 to.Tomiyasu, K.:PhaseandDoppler ErrorsinaSpaceborne Synthetic Aperture RadarImaging the OceanSurface,IEEEJour.ofOceanicEngineering,\ vol.OE-I,no.2,pp.6!S-71,November, 1976. 11.Moore, R.K.:Trade-Off Between Picture Element Dimensions andNon-Coherent Averaging in Side-Looking Airborne Radar,IEEETrans.,vol.AES-15"pp. 697-708, September, 1979. 
 When attempting to measure target size with a high-range-resolution radar, an error  car1 be incurred since tllc cxtrenlities of the target are not always good scatterers. Echoes from  the forward and rear portions of the target might be obscured in the noise, if the radar is not  sufficiently powerful.  High-range-resolution with monopuke, The inclusion of a monopulse angle-measurement to a  high-range-resolution radar was mentioned briefly in Sec. 
 Ê/ 
 Separate antennas were used fortransmitting and receiving. The main transmitting antenna was anarray, usually ofsixdipoles with suitable tuned reflectors, hung between two gantries ona350-ft steel tower. These towers were usually installed insets ofthree inorder to provide spare antennas and standby frequencies. 
 BEAM CLUTTER FALLS WITHIN THIS FILTER  AND ALL OTHER FILTERS RECEIVE SIDELOBE CLUTTER &OUR RANGE ANNULI ARE INTERSECTED BY THE MAIN 
 S. Reed: Adaptive Arrays in Airborne MTI Radar, IEEE Trans.,  vol. AP-24, pp. 
 (In the airborne case, the angle $ is the  depression angle.) Froni (b = 0 to (b = (bO, the antenna pattern is similar to a normal antenna  pattern. but from (b = 4o to # = +,, the antenna gain varies as csc2 #. Ideally, the upper limit  4, sllould be 90". 
 Dictionaries with higher number of non-zero coefﬁcients provided more detailed change maps. For future work, investigating the correlation between the quantitative metrics and the parameters in the framework (e.g., dictionary size, etc.) can provide insight into tuning the framework for different types of datasets. Other methods can be researched as alternatives to the K-SVD method in the framework. 
 Hounden. J. E., and M. 
 2016 ,13, 1158–1162. [ CrossRef ] 15. Guo, P .; Tang, S.; Zhang, L.; Sun, G.C. 
 SURFACE REFLECTION  AND III  A LATERAL OR hSURFACE 
 204–215, 1997. 119. C. 
 An accurate estimate of the target angle is given by  ˆ( ) θ θθ θ= + +1 2 121 21∆ ∆aA An /  (7.7) FIGURE 7.4  Single-sweep false-alarm probability Pfa versus threshold for moving window.  The noise is Rayleigh-distributed with s = 1. (after V . 
   !)2"/2.% -4)  Î°££ 4HE AMPLITUDE  % OF THE RECEIVED SIGNAL IS PROPORTIONAL TO THE TWO 
 SHIPS SYMBOL TO BE SHOWN ON THE RADAR DISPLAY WHEN APPROPRIATELY SHORT 
 ,Ê  /  %LSEWHERE IN THIS CHAPTER 3ECTIONS  AND   PARTICULARLY  )& BANDPASS LIMITERS  HAVE BEEN DISCUSSED AS   A MEANS OF PREVENTING RECEIVED CLUTTER SIGNALS FROM EXCEED 
 Joint Dictionary Learning for Multispectral Change Detection. IEEE T rans. Cybern. 
 R. Drinkwater, B. Holt, S. 
  
 R. Jensen: Radar Cross-Section Measurements of Insects, Proc. IEEE, vol. 
 G. Carrara, R. S. 
 LENGTHS  CAUSING HIGHER PHASE RATE  RESULTING IN HIGHER 
 OUT DURING THE PULSE IS PERMITTED  THE SYSTEM DETUNING MAY BE AS LARGE AS OS   (Z WITH NO DEGRADATION OF -4) PERFORMANCE 4O GIVE AN EXAMPLE OF INTERPULSE STABILITY REQUIREMENTS  CONSIDER A  
 Mattern: Receivers, chap. 5 of "Radar Handbook," M. I. 
 Any use is subject to the Terms of Use as given at the website. Sea Clutter. 15.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 The details of the clutter spectrum show little dependence on either the radar fre - quency or the grazing angle, at least for angles less than about 10°. In reviewing the  results of measurements at four frequencies—UHF, L, C, and X bands—Valenzuela  and Laing59 noted a relatively weak tendency of clutter bandwidth to decrease with  increases in frequency between the UHF and X bands and grazing angles between 5°  and 30°. 
 TO 
 Dokken: For High-Power Protection ... Try Multipacting, Microwaves, vol.  13, pp. 
 Tyapkin, and G. Ya. Shaidurov, “Effect of nonlinear and  focusing ionospheric properties on qualitative characteristics of radar in the decametric-wave  band,” J. 
 The signal strength indecibels is plotted against the logarithm ofthe range. Clearly distinguishable are two regions inwhich theslope corresponds respectively toanR–4and to anR–8dependence, and therelative advantage oftheshorter wavelength inthelatter region isapparent.. 52 THERADAR EQUATION [SEC. 
 FREQUENCY DISTRIBUTION  AN %ARTHS MAGNETIC FIELD  A TOPSIDE ELEC 
 71. Free. W. 
 TDWR uses clutter maps to normalize the residue from the  strong points of clutter that exceed the limit level.  The weather mode of Airport Surveillance Radars is demonstrated by five-pulse  finite impulse response (FIR) filters used in the ASR-11, an S-band radar used for  air traffic control at airports. The design of the filters is primarily for Moving Target  Detector (MTD) detection of aircraft, but special attention is given to providing flat  passband response for accurate weather reflectivity estimation. 
 Theaccuracy alongeitherthetimeaxisorthe frequency axiscanbemadeasgoodasdesired. However, theaccuracy alongtheellipsemajor axisisrelatively poor.Thisisaconsequence ofthefactthatboththetimedelay(range)andthe frequency (doppler) arebothdetermined bymeasuring afrequency shift.Thusneither therangenorthevelocity canbedetermined without knowledge oftheother. Thislimitation canbeovercome bytransmitting asecondFMpulsewhoseslopeonthe ambiguity diagram isdifferent fromthatofFig.11.12.Thesecondmodulation mightbea linearfrequency modulation whichincreases, ratherthandecreases, infrequency. 
 Other limitations, such as those  caused by transmitter distortion, limited receiver d ynamic range, and other implementation  tolerances also play an important role in reali zing a successful design, but these issues are b e- yond the scope of this paper.  While receiver and signal processor algorithms such as transversal equalizers (or the equiv a- lent) can be used to suppress the range side lobes of almost any pulse compre ssion system,  such techniques usually bring with them an extended filter time -response and have a poor to l- erance  to Doppler shifts of the r eceived returns. The use of single pulse filter banks can im- prove the Doppler tolerance but only at the cost of added pro cessor complexity. 
 This isthemost severe new requirement placed by MTI upon the modulator. Ithas been successfully met byhard-tube and byhydrogen-thyratron designs. Intheir current state, triggered- gapmodulators were notquite adequate forMTI systems in1946. 
 H. V . Hitney, “Hybrid ray optics and parabolic equation methods for radar propagation modeling,”  in Radar 92 , IEE Conf. 
 SURFACE HEIGHT REFERENCE PURPOSES  AND THE CENTRAL CONTINENTAL ICE SHEETS THAT ARE RELATIVELY LEVEL 4HE INTERFEROMETRIC MODE IS RESERVED FOR THE MORE STEEPLY SLOPING MARGINS OF THE ICE SHEETS 4HE SYNTHETIC APERTURE MODE IS USED PRIMARILY OVER SEA ICE   WHERE ITS SHARPER SPATIAL RESOL UTION AND PRECISION SUP 
 STRAINED TO BE BETTER THAN  AND  RADIAN  RESPECTIVELY 4HE TRANSMITTED PULSES  WERE LINEAR &-  AT   BANDWIDTH IN ALL THREE BANDS .OMINAL FR EE 
 See also H. S. Hewett: A Computer Designed, 720 to 1 Microwave Compression Filter, IEEE Trans., vol. 
 NEGATIVE )N THEORY  THESE NUMBERS CORRESPOND TO THE MAGNITUDE 
 That is, the ampli-  tude of a signal stored in such an integrator decays, so that the stored pulses are not sirrnnlctf  with equal weight as assumed above. Practical analog integrators such as the recirctrlati~ig  delay line (also called a feedback integrator), the low-pass filter, and the electronic storage  tube apply what is equivalent to an exponential weighting to the integrated piilses; that is, if ,I  pulses are integrated, the voltage out of the integrator is  V= 1 6 exp [-(i- l)y]  1=1  where V; is the voltage amplitude of the ith pulse and exp (- y) is the attenuation per pulse. In  a recirculating delay-line integrator, e-Y is the attenuation around the loop. 
 Knott et al., Ref. 14, pp. 209–214. 
 delay-liue integrator. also called the feedback integrator, adds each new sweep to the sum of all  the previous sweeps. To prevent unwanted oscillations, or "ringing," due to positive feedback,  the sum must be attenuated by an amount k after each pass through the line. 
 5-13, January, 1967.  44. Schwartz, M.: Effects of Signal Fluctuation on the Detection of Pulse Signals in Noise, IRE Trans.,  vol. 
 W. Der, “HF-OTH radar performance results,” Naval Res. Lab. 
 In practice, some energy is absorbed and  the reflected energy is not distributed equally in all directions. Therefore, the radar cross -section is  quite difficult to estimate and is normally determined by measurement.   The target radar cross sectional area depends of:    the airplane’s physical geometry and exterior  features,    the direction of the illuminating radar,    the radar transmitters frequency,    used material types of the reflecting surface. 
 CLUTTER MOTION AND STAG 
 To produce an ambiguity diagram such as that shown in  Fig. 11.8, the transmissions must be noiselike.  The synthesis of the waveform required to satisfy the requirements of accuracy, ambigu-  ity, and resolution as determined by the ambiguity diagram is a difficult task. 
 Figure 19.4 shows the S -band (10 cm) and Ka-band (0.8 cm) dual-polarization  doppler research radar70 operated by the National Center for Atmospheric Research  (NCAR). The system permits simultaneous measurements of the reflectivity factor on  two wavelengths, doppler parameters on the S -band wavelength, and extensive polari - metric measurements at both wavelengths. The technical characteristics are similar  to the Nexrad specifications. 
 In.Knittel.G.II.:Choosing theNumber ofFacesofaPhased-Array Antenna forHemisphere Scan Coverate. IEEETrailS.,vol.AP-13,pp.878-882, Nov.,1965. 124.Kl1lctlO. 
 IFF) I-famplifier (see Amplifier, i-f) IFF, 251 Impedance, characteristic, 391 ofdelay lines, 671 internal, ofpulser, 366 normalized, ofwavegnide, 401 Indication, true-bearing, 311 Indicator, clsseification of,164 ground position (see GPI) plan-position (see Plan-position indi- cator &PPI) radar, 161–175 radial time base, 174 range-height (nee Rang~height indi- cator) spot error, 175 (See a.ko Display) Indices, 163. 742 RADAR SYSTEM ENGINEERING Indices, ofrange andangle,513-524 Inductance, nonlinear, asswitch, 381 Inductance charging, 382 Integration, ofradar information, 38-47 Interference absorber, 69 Interference lobes, 50 Intermediate frequency, choice of,444 Intermediate-frequency amplifier (see Amplifier, i-f) Interrogator-responsor, 253 J Jacobsen Manufacturing Company, 585 Jordan, F.W., 497 Josephson, V.,77 J-scope, 166 Judson Manufacturing Company, 585 K Katzin, M.,80 Keep-alive electrode, 410 Keneipp, H.E.,56o Klystron, reflex, 414 Kock, W.E.,85 K-scope, 167 L Lawson, J.L.,33 Lebenbaum, Paul, Jr., 561 Lee regulator, 574 Leland Electric Company, 570, 573, 574 Levoy, L.G.,Jr., 56o LHTR, 208 Lighthouse tube, 207 Limiting ofvideo output signal level, 452 Line, coaxird, 393-398 coupling for, 396 rotary joint for, 396 towaveguide, transition between, 403 half-wave, 392 long, effect of,393 matched, 393 quarter-wave, 392 stub-supported, 395 Line-type pulser, (see Pulser) Linford, L.B.,77 Loaded Q,406Lobe-switching, 203 Lobes, side, 272 Local oscillator, 8,414416 MTI, design of,65%662 stability of,638-640 Local-oscillator stabilities, typical, 661 Lockover, 497 L-scope, 167 M Magnetic focusing ofCRT (see Cathode- ray tube, magnetic focusing of) Magnetron, 7,32G355 construction of,321–325 electron orbits in,33o frequency pulling of,349 frequency stabilization of,351 inductive tuning of,347 input impedance of,346 modes ofoperation for, 328 forMTI, stability of,640 output coupling of,329 performance chart for, 336 pulling figure of,349 pulse-length limitations on, 346 pulse power of,341 resonant system of,325 rising sun, 330 space-charge distribution in,335 strapped, 330 tunable, C-ring, 347 tuning of,347 wavelength scaling of,341 Magnetron cathode, back bombardment of,344 Magnetron efficiency, 345 Magnetron instabilities, 353 sparking, 353 mode-changing, 353 Marconi, G., 13 Markers (see Range, Timing, Angle, Height markers) Massachusetts Institute ofTechnology, 16 Mattress antennas, 274 Micro-B, 171 Micro-B display, 531 Microwave Committee, 15 Microwave propagation (see Propaga- tion ofmicrowaves). INDEX ’743 Microwave, reason foruse of,10 attenuation of (see Attenuation of microwaves) Mixer, 8 coaxial-type, 417 crystal for (eee Crystal, formixer) microwave, 416-418 Modulation, amplitude, 129, 139 frequency, 130 pulse, 130 from scanning, 136 Modulator, MTI requirements on, 641 (See al-w Pulser) Morse, P.M., 65 Motor-alternator sets, aircraft, 561–563 speed regulators for, 571–578 starting current of,561–563 Motor-alternator sets, speed control of, 574 Mount, antenna (see Antenna mount) three-axis, 309 Mountain relief, 96-99 Moving-target indication (see MTI) MTI, 626-679 basic principles of,62fk632 blind speeds in,650 magnetron for, stability of,640 onmoving system, 655–658 noncoherent method of,656 phase-shift unit for, 655 design of,663 special test equipment for, 677–679 target visibility in,649-653 trigger generator for, 634 MTI cancellation equipment, stability requirements on, 641 MTI component design, 65*679 MTI component requirements, summary of,642 MTI components (see particular com- ponent) MTI local oscillator, stability of,63%640 MTI locking pulse, requirements on, 662 MTI operating tests, 677 MTI oscillator stability, testing, 677 MTI receiver characteristics (see Re- ceiver, MTI, characteristics of) MTI requirements onmodulator, 641 MTI system, practical, 632-635 MTI system constants, choice of,638-655MTI targets inclutter, visibility of,651- 653 MTI transmitter, 658 Multivibrator, 497-500 cathode-coupled, 499 tip-flOp, 498 single-stroke, 498 Myers, TV.L.,283 N National Defense Research Committee (seeNDRC) Naval Research Laboratory, 14 Navigation, lightweight airborne radar system for,611–625 radar (seeRadar navigation) NDRC, 15 Division 17,216 Neild, W.G.,569 Network, pulse-forming, 375 Newton regulator, 566-570 IXTAC, 229 Noise, 2847 Noise figure, over-all receiver, 32,441 Noise fluctuations, 3.%10 Noise power, available, 30 Noise temperature, ofcrystal (seeCrys- tal,noise temperature of) Nonscanning antennaa, 277–279 Nyquist, H.,30 0 Oboe systcm, 24W247 Odographs, 216 C)lson, V.A.,655, 665 Optical superposition, ofindicator scales, 218 Oscillator, local (see Local oscillator) phase locking of,632 P Paraboloid antennas, 272-274 Peaking, series, 452 shunt, 451 Pedestal, 271 Performance chart, for magnetron (see Magnetron, performance chart for) Phantastron, 500 Phase locking ofoscillators, 632 r-mode, 326. 
 T. S. George, “Fluctuations of ground clutter return in airborne radar equipment,” Proc. 
 VELOCITY CONE AND THE GROUND IS A HYPERBOLA )F  ( IS NOT  2  THE ISODOP DIRECTION WILL NOT BE PARALLEL TO THE DOWN 
 (11.21) for VJV0 in Eq. (11.2), and then inserting Eq. (11.2) in Eq. 
 It does not  matter whether the distribution is produced by a reflector antenna, a lens, or an array.  One-dimemional aperture distributiolL Perhaps the simplest aperture distrihution to conceive  is the uniform, or rectangular, distribution. The uniform distribution is constant over the  aperture extending from -a/2 to +a/2 and zero outside. 
 The “voltage” plot shows the cumulative effect of convolv - ing the return pulse with the matched filter of each range gate. For a single range gate,  this is simply the convolution of two rectangular pulses, which results in a triangular  response. To compute loss, the matched filter output in terms of power (i.e., voltage  squared) must be used. 
 This corresponds to select pixels of a signal amplitude higher than −17 dB, since the noise equivalent sigma zero (NESZ) is estimated to be about −27 dB for PALSAR. Here, FR estimates as a function of the signal amplitude are given in Figure 4for each PolSAR scene, where the signal amplitude is deﬁned as the “circular cross-pol product” abs/parenleftbig Z12Z∗ 12/parenrightbig from Equation (2). From Figure 4, we can see that the signal amplitude of each PolSAR scene is higher than −17 dB. 
 Therearetwobasicapproaches fortakingadvantage ofthenonlinearity ofthesemetal contacts. Inoneapproach asinglefrequency istransmitted andaharmonic ofthetransmitted frequency isreceived. Thenatureofthenonlinearity oftypicalcontacts issuchthatthethird harmonic isusuallythegreatest. 
 ARH operation is used in missiles for attacking hostile radars, usually in an air-to-surface application (although air-to-air and surface-to- surface systems are also potential configurations). HOJ is an essential adjunct for semiactive and active systems to counter noise jamming.4 The radiometric homing mode has been employed as a terminal guidance mode in millimeter- wave antitank missiles.17 . Antiradiation Homing.2Q ARH systems differ from the active or semiactive air defense or the ship or ground attack systems in that they are very wideband (octave bandwidth or wider). 
 Seven particularly useful regions have been outlined on the chart. Use of the chart is illustrated by means of the region marked A, which represents the widest available spurious-free bandwidth centered at LIH = 0.63. The available RF passband is from 0.61 to 0.65, and the corresponding IF passband is from 0.35 to 0.39. 
 BANDWIDTH PERFORMANCE  OF THE TUBE  .EVERTHELESS  HIGH 
 4.16, may fall anywhere between zero and a maximum value, depending on the  exact location of the target return within the interpulse period. Figure 4.20 illustrates the effect of eclipsing and range gate straddle on the output  of the pulse matched filter over the IPP. Each range gate is assumed to be matched to  the transmit pulse bandwidth, which for unmodulated pulses (i.e., no pulse compression  modulation) is the inverse of the pulse duration. 
 Barrick, W. Stuart, and C. Krichbaum, Radar Cross Section Handbook , New York:  Plenum Press, 1968. 
 Kceti. J. E.: l'lie ANIFPS-XS Radar System, Proc. 
 Other approximate methods not dis- cussed here are explored in detail in some of the references listed at the end of this chapter. The practical engineer cannot rely entirely on predictions and computations and must eventually measure the echo characteristics of some targets. This may be done by using full-scale test objects or scale models thereof. 
 Thus, for the test cell the ranks should follow a pattern, first increasing and then decreasing. Although these detectors do not require reference cells and hence have the useful property of not requiring homogeneity, they are not generally used because of the large CFAR loss that occurs for moderate sample sizes. For instance, the CFAR losses are approximately 10 dB for 16 pulses on target and 6 dB for 32 pulses on target.33 The basic disadvantages of all nonparametric detectors are that (1) they have relatively large CFAR losses, (2) they have problems with correlated samples, and (3) one loses amplitude information, which can be a very important dis- criminant between target and clutter.34 For example, a large return (a h 1000 m2) in a clutter area is probably just clutter breakthrough. 
 MULTIPLEXED AT LESS THAN THE .YQUIST RATE !S A CONSEQUENCE  THE PHASE DIFFERENCE BETWEEN COMPLEX SAMPLES AT EACH PIXEL IS NOT AVAILABLE 4HE !3!2 ALTER 
 Substituting into Eq. (7.3) gives  4n .  Gv ~ OB<J>B (7.Sa)  Another expression for the gain sometimes used is  (7.5b)  This was derived assuming a gaussian beamshape and with 08, </>8 defined as t~e half.power  beamwidths.13 7  Power gailL The definition of directive gain is based primarily on the shape of the radiation  pattern. 
 The pixel size can be set according to the theoretical resolution of the system. Then, we obtain the RCS curve through the 360◦observation of each pixel. The coherent complex image In(i,j)of each sub-aperture is the imaging result by using the BP algorithm. 
 52–63, October 2001. 178. G. 
 It has  also allowed the ready incorporation of the quadrature channel for elimination of blind  phases. In short, digital MTI has allowed the radar designer the freedom to take advantage of  the full theoretical capabilities of doppler processing in practical radar systems.  The development of digital processing technology has not only made the delay-line  canceler a more versatile tool for the MTI radar designer, but it has also allowed the applica-  tion of the contiguous filter bank for added flexibility in MTI radar design. 
 170-171, May 3, 1968. 75. McCaIl, E. 
 33, pp. 1067, July–August 1998. 78. 
 For  example, a sequential burst of pulses can be transmitted at the beginning of the transmission,  with each pulse radiated in a different direction. This requires rapidly switching phase shifters  to steer the beam between pulses. It also requires an application where a short minimum range  is not important since reception cannot take place during the transmission of the burst of  Till'I:.I.ITIHONH"AI.I.Y STI'ERED "liASI'D ARRAY ANTENNA INRADAR317 Inprinciple, multiple receiving beamscanbegenerated utilizing theFastFourierTrans­ form(FFT)processor. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar.  PULSE DOPPLER RADAR  4.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 FIGURE 4.8  Typical pulse doppler radar configurationFFTEnvelope DetectorPDI CFARDetection  EditingRange/  Doppler  CorrelationDwell  Target  ReportTo  Mission  Processor &  Operator  Display FFTPulse  CompressionPulse  Compression Pulse  Compression Pulse  CompressionAvg FFTElevation  Angle  MeasurementAvg FFT GuardEnvelope DetectorPDIAzimuth  Angle  MeasurementSignal ProcessorFrom ReceiverAntenna Receiver  ProtectorCAGC LNA NAGC ∆AZ ∆AZ∆EL ∆ELGuardIF  Matched FilterDigital I/Q  GenerationDigital Matched  FilterA/DMaster  OscillatorReference  Generator SynchronizerSynthesizerClutter Offset  GeneratorOutput  GeneratorPower AmpTransmit LO1  Generator LO1Clock LO2Beam Steering Computer Same as Σ Channel Same as Σ Channel Same as Σ Channel To Signal ProcessorControl  ProcessorMode  Control  Mission  Processor Digital Controls to  Individual  Components Data ProcessorINS CFARRFI  Edit RFI  Edit RFI  Edit RFI  EditΣ Σ ch04.indd   11 12/20/07   4:52:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 322 -337. December, 1972.  29. 
 In . Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  123     general, LCFAR decreases with an increasing CFAR -window length and LCFAR increases with a  decreasing CFAR -window length.  12.1.8  Conclusions   It is possible that the OS -CFAR is combined with the CAGO - and CA- CFAR in a wide range  of ways. 
   !. ).42/$5#4)/. !.$ /6%26)%7 /& 2!$!2   £°£x (&  TO  -(Z   4HE MAJOR USE OF THE (& BAND FOR RADAR #HAPTER   IS TO  DETECT TARGETS AT LONG RANGES NOMINALLY OUT TO  NMI  BY TAKING ADVANTAGE OF THE  REFRACTION OF (& ENERGY BY THE IONOSPHERE THAT LIES HIGH ABOVE THE SURFACE OF THE EARTH 2ADIO AMATEURS REFER TO THIS AS  SHORT 
 STAGE DESIGNS  IT IS NECESSARY THAT THE FINAL STAGE OF THE AMPLIFIER REACH SATURATION BEFORE THE PRECEDING STAGES 4HIS MUST BE ADDRESSED IN THE CIRCUIT DESIGN ,OW 
 P. K. Kadaba, “Penetration of 0.1 GHz to 1.5 GHz electromagnetic waves into the earth surface  for remote sensing applications,” in Proc. 
 In this case, we could  provide a mechanism to set the phase to the desired value at the beginning of a pulse  instead of simply clearing it. The DDS can also be used to generate linear and nonlinear FM “chirp” waveforms.  This is accomplished by providing circuitry that changes the tuning word from sample  to sample in order to provide the desired frequency (or phase) modulation. 
 Their life is limited by exposure  to ultraviolet light. surface erosion, and the constant flexing of the material in the wind. In high  winds the material can he damaged by flying debris and the rotation of the antenna might have  to cease to prevent the fabric from being blown against the antenna and torn. 
 The Perspex graticule on the PPI could be rotated to align with theﬂight marker, or offset to indicate a track drift angle. The alignment of the display and the scanner position was achieved using the heading control unit, whichallowed the operator to set the magslip stators which controlled the orientation of the picture of the PPI. The Lucero switch controlled the display on the height tube. 
 SUM  B  THE TARGET DIRECTION 
 Theantenna patternisaplotofantenna gainasafunction ofthedirection ofradiation. (A typicalantenna patternplottedasafunction ofoneangularcoordinate isshowninFig.7.1.) Antenna beamshapesmostcommonly employed inradararethepencilbeam(Fig.2.27(1)and thefanbeam(Fig.2.27b).Thepencilbeamisaxiallysymmetric, ornearlyso.Beamwidths of typicalpencil-beam antennas maybeoftheorderofafewdegreesorless.Pencilbl:amsare commonly usedwhereitisnecessary tomeasure continuously theangularposition ofatarget inbothazimuth andelevation, as,forexample, thetarget-tracking radarforthecontrolof weapons ormissileguidance. Thepencilbeammaybegenerated withametallic rdlector surfaceshapedintheformofaparaboloid ofrevolution withtheelectromagnetic energyfed fromapointsourceplacedatthefocus. 
 LENGTH EQUAL TO ONE 
 The data is  taken from Julian days 180 and 360 of 2000 and 2005. ch20.indd   42 12/20/07   1:16:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Reed. R. H.: Modified Magic Tee Phase Shifter, IRE Trans., no. 
 S.: Microstrip Disc Element Reflect Array, I EEE EASCON '78 Record, pp. 186- 192.  Sept. 
 111, 130  clutter fluctuations. 131 134  clutter-lock. 142  clutter map, 127  coherent reference. 
 CALLED PER 
 PLEX CONJUGATE TRANSPOSE OPERATION 4HE AMPLITUDE  B CAN BE SEPARATELY ESTIMATED BY  NULLING THE FIRST DERIVATIVE OF THE FUNCTION TO BE MINIMIZED " Y REPLACING THE AMPLI 
 The cross-le~lel urryle is the angle.  rlleasured about tlie lirle of sight, betwee11 tile vertical plane through the line ofsiglit and tlie  11laric ~xrl~e~icfict~lar to tlic deck tllrotrgli [lie line of sight.  :\II~CIIII~ drivr~s.' '".' " Mccllit~~ical trnckirig radars arid nodding-bcarn liciglit firiders reqtiisc  v;~r-i;~ hle clrivc power. 
 MODULATED CONTINUOUS 
 DEFOCUS VARIATIONS ALONG THE SURFACE ILLUMINATION PROFILE  OR A GENERAL RISE  IN THE LOCAL GRAZING ANGLE &IGURE  GIVES AN EXPERIMENTAL EXAMPLE OF THE EFFECT  OF DUCTING ON VERY LOW 
 Although no power is  radiated into imaginary space, the concept is useful for observing the motion of grat - ing lobes as the array is scanned. In addition, the pattern in imaginary space represents  stored energy and contributes to the element impedance in the array. The most common element lattices have either a rectangular or a triangular grid. 
 It is a good technique . 544 INTRODUCTION TO RADAR SYSTEMS  from a fundamental point of view since it uses simultaneous pencil-beam radiation patterns  from a single aperture to cover the elevation angles of interest. Each beam can be considered a  separate radar. 
 SARILY SATISFIED FOR SCENES  SUCH AS ICE OR VEGETATION  THAT MAY UNDERGO CHANGES IN THE DETAILS OF REFLECTION AND SCATTERING BETWEEN OBSERVATIONS )N CERTAIN NATURAL AND MOST URBAN SCENES  THERE WILL BE MANY CORNER 
 STATE DRIVER AND THE 474 POWER BOOSTER IN THE RATIOS FROM  TO  4HE -0- SEEMS BEST SUITED FOR THE HIGHER MICROWAVE FREQUENCIES  PERHAPS FROM  TO  '(Z ! SERIOUS CONSTRAINT OF THE -0- FOR RADAR APPLICATIONS IS THAT THE HELIX 474 LIMITS  ITS USE TO #7 OR HIGH DUTY CYCLE TRANSMISSIONS PREFERABLY GREATER THAN   )T ALSO IS OF RELATIVELY MODEST POWER FOR MANY RADAR APPLICATIONS&)'52%   #OMPARISON OF THE STRUCTURES OF A CONVENTIONAL STAGGER 
 The time separation of the targets is related to their physical spacing as well as  the velocity of propagation, which can vary depending on the material properties. Where the targets are well separated in range, it is relatively straightforward to  separate the radar reflections, but this becomes progressively more difficult as targets  become closer together, as instead of separable time-domain signatures the reflections  will merge together. As the antennas generally used for GPR have poor directivity, the pattern of the  reflected waveform in the B-scan represented the spatial convolution of the antenna  pattern with the target. 
 Theseletterdescriptions ofradardisplays datebacktoWorldWarII.Theyare notallincurrentusage;however, thePPI,A-scope, B-scope, andRHIareamongthemore usualdisplays employed inradar.Therearealsoothertypesofmodernradardisplays not included intheabovelistingwhichhavenotbeengivenspecialletterdesignations. These includethevarioussynthetic andrawvideodisplays withalphanumeric characters andsym­ bolsforconveying additional information directlyonthedisplay. CRTscreem. 
 Rossow, S. L. Durden, S. 
 NOISE RATIO AND PROBABILITY OF FALSE ALARM  0&!   WHICH  ITSELF IS A FUNCTION OF WAVEFORM 4HE FALSE ALARM PROBABILITY D ETERMINES THE DETECTION  THRESHOLD AND IS REFERENCED TO AN INDIVIDUAL RANGE 
 1.8 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 Angular Direction.  One method for determining the direction to a target is by  determining the angle where the magnitude of the echo signal from a scanning antenna  is maximum. This usually requires an antenna with a narrow beamwidth (a high-gain  antenna). 
 If the single scan probability of detection for a surveil­ lance radar is Pd, the probability of detecting a target at least once during N scans is called the  cumulative probability of detection, and may be written  (2.56)  The variation of Pd with range might have to be taken into account when computing P,. The  variation of range based on the cumulative probability of detection can be as the third power  rather than the more usual fourth power variation based on the single scan probability. 59  The cumulative probability has sometimes been proposed as a measure of the detectabi­ lity of a radar rather than the single-scan probability of detection, which is more conservative. 
 During thesaw-tooth alarge positive voltage isinduced inL1,and Clischarged accordingly. When the current derivative reverses attheend ofthesawtooth, thevoltage is temporarily maintained atahigh level byC,,and, inspite oftheinduced voltage across thetransformer, the plate ofthetube remains atawork- able voltage level during therapid back-swing. The choice ofpolarities issuch that theinterval inwhich Claids theplate supply isshort.. 
 The outputs of identical  single-stage power amplifiers are commonly summed by using well-documented28  splitting and combining techniques (Figure 11.14). These techniques also address   isolation between paralleled amplifiers. Having isolation between adjacent ports  means that if one device fails, the power combiner provides a fixed load impedance  to the remaining device; however, half the power of the remaining active device will  be dissipated in the isolation resistor of the combiner. 
 In particular, IMO issues requirements and guidelines on the  installation and use of radar equipment on commercial ships. These are vigorously  enforced by the laws of individual maritime states. The purpose of shipborne radar, as  defined by IMO, is to “assist in safe navigation and in avoiding collision by providing  an indication, in relation to own ship, of the position of other surface craft, obstruc - tions and hazards, navigation objects and shorelines.”2 The International Association  of Marine Aids to Navigation and Lighthouse Authorities3 (IALA) recommends oper - ational and technical requirements for VTS radars. 
 Thefullyadaptive arrayof largesizeis,intheory,capable ofnullingalargerregionofspacethanasystemwithbuta relatively fewadaptive elements, asinthesidelobe canceler. However, theaddedcomplexity andlongerconvergence timethataccompanies thegreaterdegreesoffreedom ofthelarge, fullyadaptive arrayhasbeenaburdenthatisdifficult tojustifyonacost-effective basisfor generalapplication. Theobje~tive oftheusualadaptive antenna orthecoherent sidelobe canceler istoadjust thesidelobelevelstominimize theeffectsofnoiseorotherunwanted signals.Iftheradar application allowstheuseofantennas withextremely lowsidelobes, thesameresultwillbe achieved aswiththeadaptive antenna. 
 02& RANGING AND STORE THE RANGE  ANGLE  AND DOPPLER OF THE REPORTED DETEC 
 The multicavity klystron has always been known for its high-FIG. 4.7 Pedestals on a CFA RF output pulse.PEDESTALSPOWER . gain and high-power capability. 
 Therefore, for the purposes of the  present discussion, the operator will be considered the same as an electronic threshold detec­ tor, an assumption that is generally valid for an alert, trained operator.  The signal-to -noise ratio necessary to provide adequate detection is one of the important . 18 INTRODUCTION TO RADAR SYSTEMS  parameters that must be determined in order to compute the minimum detectable signal. 
 286INTRODUCTION TORADAR SYSTEMS weretoarriveinadirection otherthanbroadside, theentirearraywouldnotbeexcited simultaneously. Thecombined outputs fromtheparallel-fed elements willfailtocoincide or overlap, andthereceived pulsewillbesmeared. Thissituation mayherelieved hyreplacing the 2rrmodulo phaseshifterswithdelaylines. 
 COMPRESSION SYSTEMS HAVE NOT DELIBERATELY PROVIDED THE  &)'52%  -4) WITH PULSE COMPRESSION . Ó°Çn  2!$!2 (!.$"//+  TWO SEPARATE LIMITERS DESCRIBED ABOVE  BUT THE SYSTEMS WORK BECAUSE DYNAMIC RANGE IS  SUFFICIENTLY RESTRICTED BY CIRCUIT COMPONENTS /THER SYSTEMS  SUCH AS THOSE THAT DELIB 
 The klystron is  sometimes thought of as having a narrow bandwidth and the traveling wave tube is  thought of as having wide bandwidth; but at the high power levels needed for long  range radars, their bandwidths are comparable. It is sometimes unfortunate that this  fact is not always understood.4 The klystron, as an example of a linear-beam tube, is capable of high power  because the generation of the electron beam, its interaction with the electromagnetic  field, and the collection of the spent electrons are performed in separate parts of the  tube where the generated heat can be dissipated effectively. The klystron and other linear-beam tubes can have long life. 
 NORMAL DISTRIBUTIONS SHOWN FOR COMPARISON DASHED LINES  4HE ORDINATE IS THE  PERCENT OF TIME  FOR WHICH THE ABSCISSA IS EXCEEDED   AND THE ABSCISSA IS THE VALUE OF  R    AS DEFINED BY  %Q   WITH ! TAKEN FROM %Q  OR %Q  AS APPROPRIATE 4HIS PARTICULAR DISTRI 
 362-HO.  September, 1948.  79. 
 SEC. 125] SECOND DETECTOR 449 This combined response curve hasthesame shape asthat foratransi- tionally coupled double-tuned circuit, sothat theadvantage ofcascading ispreserved. Inactual practice, areceiver that hasagain of100dbwith, forexample, sixstages, will beapproximately twice aswide ifstaggered pairs areused asitwould beifsingle-tuned circuits were used (Fig. 
 Thus, for example, the largest waves in a fully developed sea for a 15-kn (7.5 m/s) wind will have a wavelength of about 120 ft (36 m) with a period of 5 s. The statistical distribution of waveheights on the ocean surface is quite close to gaussian, with a mean square deviation that can be obtained by integrating the waveheight spectrum over all frequencies (or wavenumbers). For spectra resem- bling those in Fig. 
 Also, it requires more research on rapid InISAR near-ﬁeld 3-D imaging approach in combination with the traditional near-ﬁeld imaging approach for future study. Author Contributions: Y.F. was responsible for all of the theoretical work, performed the simulation and analyzed experimental data; B.W., Z.S. 
 105 PulseVoltage.—The input impedance’ ofmost pulsed magnetrons lies between 700 and 1200 ohms. For example, magnetrons with aninput of260kw(100-kw output) require apulse voltage ofabout 15kv;inputs of2500 kw(1000-kw output) require 30kv,and one magnetron designed for6000-kw input (2500-kw output) requires apulse voltage of50kv. Serious attempts have been made todesign magnetrons that would operate atlower input impedances because such tubes would simplify the design ofline-type pulsers. 
 TIONS IN &IGURE  ARE ALL VARIANTS OF A &%4 !N EXTERNAL VOLTAGE  APPLIED TO THE GATE TERMINAL OF A &%4  CONTROLS THE WIDTH OF THE DEPLETION REGION BELOW THE GATE TERMINAL !S THE WIDTH OF THE DEPLETION REGION IS VARIED  SO TOO IS THE EQUIVALENT RESISTANCE BETWEEN . ££°È  2!$!2 (!.$"//+  THE DRAIN AND SOURCE CONTACTS  ALLOWING THE CURRENT FLOWING BETWEEN THE DRAIN AND SOURCE  TO BE MODULATED ACCORDINGLY HENCE  &%4S ARE REFERRED TO AS  VOLTAGE CONTROLLED DEVICES   4HERE EXIST NUMEROUS &%4 VARIANTS DUE TO SOMETIMES SUBTLE CONSTRUCTION OR MATE 
 FREQUENCY INTERFERENCE #OHERENT RADAR PERFORMANCE IS EVEN MORE AFFECTED BY SPURIOUS MIXER CHARACTERIS 
 N-est oftheaircraft amountai nchainrisin gto6000ft throws long shadowsintothe 310gami Yalley beyond. ‘1’heto\vnof Yarnagata isseen asabright signal beyond aspur ofMt. Taki extending northwest. 
 A., and R. Wexler: A Determination of Kinematic Properties of a Wind Field Using Doppler Radar, J. Appl. 
 Once the channel is equalized, a unique time delay is implemented for  each beam to be formed. As mentioned earlier, this time delay can be realized either  as a phase shift for a narrowband system or as a time delay for a wideband system. A  phase shift can be implemented with a complex multiply or a CORDIC operation, both  of which will be described later. 
 Practical targets are composed of many individual scatterers, each  with different scattering properties. Also, interactions may occur between the scatterers whlct~  affect the resultant cross section.  An example of the cross sect~on as a function of aspect angle for a propeller-driven  Sphere  target  Figure 2.14 Geometry of t he t wo-scatterer complex target. 
 Rough ejecta give rise to strong radar  return, a blessing for those interested in planetary geology. ( Courtesy of NASA ) ch18.indd   45 12/19/07   5:15:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 FICIENTLY GREAT  THE SIGNAL FROM A PRECIPITATION CELL BEHIND A REGION OF STRONG ABSORP 
 The MRA 5 operates within the 10 to 10.5 GHz band, from 100 m to  50 km range with an accuracy of k0.05 m + d, assuming a correction is made for  meteorological conditions.  In addition to its use in surveying, the multiple CW frequency method of measuring range  has been applied in range-instrumentation radar for the measurement of the distance to a  transponder-equipped missile;65 the distance to satellites;66 in satellite navigation systems  based on range rnea~urement;~~ and for detecting the presence of an obstacle in the path of a  moving automobile by measuring the distance, the doppler velocity, and the sign of the  doppler (whether the target is approaching or re~eding).~'  REFERENCES  1. Sandretto, P. 
 The troposphere is typically a nonhomogeneous  medium for propagation and will cause random beam bending. Figure 9.29 illustrates  the approximate relation of rms angle error to various atmospheric conditions.22 The  worst case is heavy cumulus clouds, which cause columns of air, shaded from the  sun by the clouds, that are cooler than the surrounding air and consequently of a  different dielectric constant. The result is typically a random beam bending as the  radiated energy passes through these columns. 
 TABLE   8. 8 Comparisons of Performance Characteristics for LFM, NLFM, and Phase-Coded  Waveforms ch08.indd   27 12/20/07   12:50:43 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 BAND  
 Bistatic cross sections are more complex than monostatic cross sections in  the optical region since sB is a function of aspect angle and bistatic angle b.* Three  bistatic RCS regions are of interest in the optical region: pseudo-monostatic, bistatic,  and forward scatter. Each region is defined by the bistatic angle. The extent of each  region is set primarily by the target’s physical characteristics. 
 the gradient in density is sufficient, the wave will "reflect" back back to the earth, providing long-distance illumination. The lower the radio-wave frequency, the smaller the required gradient. Since some ionization in the upper atmosphere always exists, it is always possible to illuminate the earth over the horizon if there is freedom in frequency selection. 
 These considerations have led to  the development of airborne MTI (AMTI)1,2,3 radar systems similar to those used in  surface radars,1,4–6 discussed in the preceding chapter. The mission requirements for an AEW radar drive the need for 360° azimuthal cov - erage and long-range detection capability. The 360° azimuthal coverage requirement  is because the AEW radar system is generally required to provide the first detection of  airborne targets, without any a priori knowledge of the location of these targets. 
 But a  sine wave of infinite duration and an infinitesimal bandwidth cannot occur in nature. The  more normal situation is an echo signal which is a sine wave of finite rather than infinite  duration. The frequency spectrum of a finite-duration sine wave has a shape of the form  [ sin rr(f-/~)c5]/rr(.f -lo), where lo and c5 are the frequency and duration of the sine wave,  respectively, and l is the frequency variable over which the spectrum is plotted (Fig. 
 SPACE  PROPAGATION CHARACTERISTICS AND A LENGTH  , EQUAL TO THE SIZE OF THE APERTURE THAT IT FEEDS  WILL PRODUCE A LINEAR 
 THE RADAR EQUATION 51  The log-normal distribution has also been considered for representing target echo nuctua­ tions. It can be expressed as  p(a) = (J > 0 (2.42)  where s4 standard deviation of In (a/am), and <Tm= median or a. The ratio orthe mean to the  median value of a is exp (sJ/2). 
 CYCLE WAVEFORMS  TO   ARE THERE 
 To solve this prob - lem the signal could be moved to a different center frequency before sampling or  the sampling rate could be increased. The system designer must always develop the  frequency plan of a sampling system carefully to determine an appropriate sampling  frequency and to ensure that aliasing does not occur. A full treatment of this subject is  presented by Lyons.2 In an actual system, before sampling the signal is typically passed through an  anti- aliasing filter , which is an analog lowpass or bandpass filter that places an upper  limit on the signal bandwidth. 
 Wiseman, “P-3 ultrawideband SAR: System  applications to foliage penetration,” Proceedings SPIE , vol. 2757, pp. 130–135, 1996. 
 Ê-* 
 L. Lucas, S. McCammon, R. 
 I. Skolnik (ed.),  McGraw-Hill Book Co., New York, 1970, sec. 11.9. 
 RAYS  HAVE HIGH ELECTRONIC EFFICIENCY UP TO  PERCENT   AND HAVE THE POTENTIAL FOR A HIGHER INSTAN 
 Harger, R. 0.: "synthetic Aperture Radar Systems: Theory and Design," Academic Prcss, New  York, 1970. >  4. 
 Thedesignflexibility available withtheklystron isnotpresentinothertubetypescon­ sideredinthischapter, exceptforthetraveling-wave tube.Tnmostothertubesthefunctions of electron emission, RFinteraction, andcollection ofelectrons usuallyoccurinthesameregion. Thedesignofsuchtubesmusttherefore beacompromise between goodRFperformance and goodheatdissipation. Unfortunately, theserequirements cannotalwaysbesatisfied simulta­ neously.GoodRFperformance usuallyrequires thetubeelectrodes tobesmallcompared with awavelength, whilegoodheatdissipation requires largestructures. 
 52. H. Zebker and J. 
 MONITORING SYSTEMS BY THE 3OVIET 5NION ;USING THE 4OROS  + U 
  INDICATED THAT THIS LACK  OF ANGULAR VARIATION OF  R   ALSO IS  PRESENT AT  '(Z  4HE MODELS DESCRIBED ABOVE ARE  BASED ON AVERAGES OVER VERY LARGE AREAS &OR THIS SITUATION  THE VARI 
 TO 
 MODE  FLARED HORNS WILL PROVIDE LINEARLY POLARIZED PENCIL BEAMS AND WILL GENERALLY HANDLE HIGH POWER &OR MORE DEMAND 
 LOPE OF THE TRANSISTOR !LSO  THERE IS AN OPTIMUM LOAD IMPEDANCE THAT WILL MAXIMIZE THE POWER OUTPUT THAT CAN BE DELIVERED FROM AN AMPLIFIER AND TO A FIRST ORDER ESTIMATE  THAT LOAD IMPEDANCE IS REPRESENTED BY THE LINE THAT TRANSVERSELY CUTS ACROSS THE ) 
 CALLED COMPOUND SEMICONDUCTORS  SUCH AS GALLIUM ARSENIDE 'A!S   INDIUM PHOS 
 AES-12, pp.  405 408. Mav. 
 Two-Channel Monopulse.  Monopulse radars may be designed with fewer than the  conventional three IF channels. This is accomplished, for example, by combining the sum  and difference signals in two IF channels and the sum and two difference signal outputs  are then individually retrieved at the output. 
 15.60  Accuracy  ...........................................................  15.60  15.13 Adaptive MTI Impl ementation  .................................  15.61  15.14 Clutter Map Implementation  ................................... 
 2!.Collins, G.W.:Shaping ofSubreflectors inCassegrain Antennas forMaximum Aperture Efficiency, IEEETrans.,vol.AP-21,pp.309-313, May,1973. 22.Graham, R.:ThePolarisation Characteristics ofOffsetCassegrain Aerials,"Radar -Present and Future," Oct.23-25,1973, lEECOI!fPI/hi.no.105,pp.134-139. 23.Dahlsjo,0.:ALowSideLobeCassegrain Antenna, "Radar- PresentandFuture," Oct.2325,1973, lEECOt!fPubl.110.105,pp.408-413. 
 98.Kossiakolf. 1\..andJ.R.Austin: Automated RadarDataProcessing System. U.S.Patent4,005,415. 
 Plane wave s, whereby only the far field characteristics will be dealt with,  can be scattered more or less directed by dielectric or metallic bodies.  This scattering is addi- tionally dependent upon polarization.  The amount and/or strength of this scattering is d e- scribed by the RCS ( Radar  Cross-S ection ). 
 Most radars employ amplifiers prior to STC; so they cannot attenuate external interference without affecting the noise level which they desire to sense, and the servo must be designed to tolerate pulses from other radars and echoes from rainstorms or mountains at extreme range. This interference occasionally can be of high amplitude but generally has a low duty cycle during a 360° scan; so the preferred servo is one which increments a counter when any sample is below the desired median noise level and decrements the counter when the sample is above that level, independently of how great the deviation is. The most significant bits of the counter control the gain, and the number of bits of lesser significance in the counter dictates the sluggishness of the servo. 
 STC  turns down the gain at close ranges, thereby reducing sidelobe clutter signals. Clutter large  enough to appear in the sidelobcs of a logarithmic receiver might not be suppressed and may  confuse the radar display. For this reason STC and logarithmic receivers are sometimes used  together. 
 16163–16178, 1995. 123. E. 
 NOISE VOLTAGE LEVEL AT THE !$ CONVERTER IS GIVEN IN TERMS OF  QUANTA  ! SINGLE QUANTA REFERS TO A UNIT QUANTIZATION LEVEL OF THE !$ CONVERTER &ROM THE RELATIONSHIP DESCRIBED ABOVE AND ASSUMING THE !$ CONVERTER LIMITS THE  DYNAMIC RANGE  THE !$ CONVERTER SIZE CAN NOW BE DETERMINED !DDITIONAL MARGIN TO  ALLOW FOR MAIN 
 When extensive vertical coverage is required, the  aircraft’s planform and vertical stabilizer distort and shadow the antenna pattern.  Analysis of tactical requirements may show that only a limited coverage sector is  required. However, this sector usually has to be capable of being positioned over the  full 360 ° relative to the aircraft’s heading because of the requirements for coverage FIGURE 3.1  E-2D airborne early-warning (AEW) aircraft showing rotodome  housing the antenna ch03.indd   2 12/15/07   6:02:41 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 SPEED NOTCHES   WHICH ELIMINATES THE TRANSIENT SETTLING PROBLEM OF THE FEEDBACK FILTERS 4HE OPTIMUM CHOICE OF THE STAGGER RATIO DEPENDS ON THE VELOCITY RANGE OVER  WHICH THERE MUST BE NO BLIND SPEEDS AND ON THE PERMISSIBLE DEPTH OF THE FIRST NULL &)'52%   3HAPED 
 LOOK WITHIN A DWELL PRODUCES 3WERLING )) AND )6 STATISTICS AND IS BETTER SUITED FOR HIGH SINGLE 
 OF 
 Hall and W. W. Shrader32  © IEEE 2007 )30° 210°60° 240°90° 270°120° 300°150° 330°180°0° Volts1.02.03.0 4.05.0 START1020 30 40 50 60 FINISHFIGURE  2.66 Mean improvement factor restriction versus amount of limiting and  clutter spectral spread for a four-pulse canceler ( after T. 
 The concept of using a small bistatic receiver that "hitchhikes" off airborne radars was also developed and successfully tested.54 It alerts and cues autono- mous short-range air defense and ground surveillance systems to improve surviv- ability and acquisition performance. This hitchhiking concept was extended to other transmitters of opportunity, including a commercial television station that served as a bistatic transmitter. Initial attempts to detect aircraft were only mar- ginally successful.55 Bistatic radars using space-based transmitters and receivers that are either space-based, airborne, or ground-based have been studied.3'56"59 Limited field tests were conducted by using a communication satellite as the transmitter and a ground-based receiver to detect aircraft.58 Since the effective radiated power of the satellite was modest and the transmitter-to-target ranges were large, detection ranges were small, <4 km, unless a very large receive aperture was used. 
 MENTATION OF 3,# AND MORE GENERAL ADAPTIVE ARRAY PROBLEMS IN THE LITERATURE   4HE  RATIONALE AND THE USE OF A SYSTOLIC ARRAY THAT PROCESSES THE SIGNALS RECEIVED BY 3,# AND MAIN CHANNEL IS REPORTED ON PAGES n OF &ARINA  AND IN &ARINA AND 4IMMONERI  &IGURES  TO  DEPICT THE USE OF A SYSTOLIC PROCESSING SCHEME THAT INCORPORATES THE  3," AND 3,# 4HE ADVANTAGE OF THESE SCHEMES RESIDES IN THE DECOMPOSITION OF THE COMPLEX PROCESSING FOR ADAPTIVE CANCELLATION OF THE .,) INTO A NETWORK OF SIMPLE PROCESSING ELEMENTS THAT CAN BE CONVENIENTLY MAPPED ONTO A PARALLEL PROCESSING ARCHI 
 Rept. 389, May 17. 1965. 
 R. B. Mack, C. 
 (a) ( b)       (c) ( d)  Figure 11. Refocused images of ship03 sub-image. ( a) Sub-image of ship03; ( b) Refocused image with DCT method; ( c) Refocused image with PGA method; ( d) Refocused image with proposed method. 
 Ryan. C. P. 
 61.Bohnert. J.I..andH.P.Coleman: Applications oftheLuneburg Lens,NavalResearch Lob.Rt>pt. 4X88.Mar.7.1957. 
 However, the usual estimate of the standard deviation  ˆ ( ˆ) σ µ = ∑ −  1212 Nxi  (7.13) where  ˆµ= ∑1 Nxi (7.14) FIGURE 7.14  Ratio detector ( from G. V . Trunk7) FIGURE 7.15  Curves of probability of detection versus signal-to-noise ratio per pulse for the  cell-averaging CFAR, ratio detectors, log integrator, and binary integrator: nonfluctuating target,  N = 6, 2m = 16 reference cells, and Pfa = 10−6 (from G. 
 Insome cases, this synchronization has been accomplished byusing the same parabolic reflector with separate feeds forthe two frequencies. Ifthefrequency ofthebeacon isclose tothat oftheradar set, other problems arise. The same antenna can beused, but then the design of the duplexing system becomes more complex than itisforthe simple radar set. 
 Contents     xxix   The Unfocused Synthetic Aperture  .....................  21.5  The Focused Case  ............................................  21.6  21.3 Radar System Prel iminaries  ................................... 
 2016 ,13, 1726–1728. [ CrossRef ] 9. Jia, L.; Li, M.; Zhang, P .; Wu, Y. 
 ARRAY IS AN AGGREGATION OF ANTENNA ELEMENTARY RADIATORS THE WHOLE ANTENNA CAN BE CONSIDERED AS AN ARRAY OF THESE SUPER ELEMENTS !DAPTIVE PROCESS 
 Thisassumesf,>fd'If,ontheotherhand,f,<fd' suchasmightoccurwithahigh-speed targetatshortrange,therolesoftheaveraging andthe difference-frequency measurements arereversed; theaveraging meterwillmeasure doppler velocity, andthedifference meter,range.Ifitisnotknownthattherolesofthemetersare ...---.-'Tronsmtlted s/qno/ //--Rece/ved s:.znol ~"'-........>­u C QJ ::Jo ~lo~-----"-.::--''''''r----'".p:c---~~---~",=-­ LL (a) >- t'~1Ir-IdjIr+fd \/m (b)\ TimeFigure3.12Frequency-time relation­ shipsinFM-CW radarwhenthe received signalisshiftedinfrequency bythedopplereffect(a)Transmitted (solidcurve)andecho(dashedcurve) frequencies; (b)beatfrequency.. reversed because of a change in the ineqiiality sign \~ctwccn 1, and /,, arl lrlcorrect Interprcta-  tlon of the measurements may result.  When more than one target is present within the view of the radar, the mixer oiitpilt w~ll  contain more than one difference frequency. 
 The signal reemitted by a particular generic point of the asteroid or from the entire surface is a delayed copy of a pulsar signal and can be interpreted as a time-frequency grid signal model with time delay. The pulsar’s main pulse train with Lmicrobursts reemitted by the g-th asteroid’s generic point and registered in the r-th frequency channel is modeled by the expression ˆsr,g(t)=N−1⎭summationdisplay p=0L−1⎭summationdisplay l=0ag·exp⎡ ⎢⎢⎢⎢⎢⎢⎢⎣−⎭bracketleftBig t−Tpl−tg⎭bracketrightBig2 2σ2 l⎤ ⎥⎥⎥⎥⎥⎥⎥⎦·exp⎭bracketleftBig j·2π·f r·(t−Tpl−tg)⎭bracketrightBig , (4) where agis the amplitude of the reemitted l-th microburst from the g-th generic point; σl=T/2 is the time dispersion of the Gaussian microburst; Tis the microburst’s time width; tg=tg(p)= Rg(p)/c is the time delay of a reemitted signal by the g-th generic point from the object’s surface; Rg(p)= ⎭bracketleftBig x2(p)+ y2(p)+ z2(p)⎭bracketrightBig1 2is the current distance to the particular generic point from the object; cis the speed of light in vacuum. 108. 
 BASED DISPLAY 3EARCH RADARS ARE NOT THE PRIMARY TARGET FOR THESE SYSTEMS  THOUGH RANGE ADVANTAGE DUE TO ONE 
 Trunk, G. V.: Radar Properties or Non-Rayleigh Sea Clutter, I EU:: Trw1s., vol. Al:S-8, pp. 
   
 THE MAGIC EYE  F ALL RADAR SYSTEMS PERHAPS THE MOST COLOURFUL  in its practical application is that branch of airborne  centimetric radar known by the generic code-name  handed down from the war years, H2S.  This is the ‘television’ airborne radar system which  on a PPI tube gives a very reasonable map of the ground  over which the aircraft is flying. Variations of the system  were used during the war years for ASV search, as the  system which can ‘draw’ a map of the ground can equally  show up vessels on the ocean surface below. 
 ABILITY OF DETECTION CURVE FOR THE !LERT DWELL WITH THAT OF THE #ONFIRM DWELL RESULTS IN AN ESTIMATE OF THE COMPOSITE  0 D VS 3. CURVE FOR !LERT#ONFIRM -ORE ACCURATE  RESULTS MUST INCLUDE THE EFFECTS OF LATENCY BETWEEN THE !LERT AND #ONFIRM DWELLS 3EARCH DETECTION PERFORMANCE IS OFTEN CHARACTERIZED BY THE CUMULATIVE PROBABIL 
 WEIGHT CANCELER 4HE RATE OF CHANGE OF PHASE OR AMPLITUDE OF CLUTTER SIGNALS IN A SCANNING RADAR IS  INVERSELY PROPORTIONAL TO THE HITS PER BEAMWIDTH   N 4HUS  WITH THE USE OF A COMPUTER  SIMULATION TO DETERMINE THE PROPORTIONALITY CONSTANT  THE LIMITATION ON  ) DUE TO STAG 
 (36) istoincrease the strength ofthe signals atclose ranges above those atmedium and long ranges. This increase isnot large, amounting only to3dbat60°; itsmain effect istomake thealtitude signal stronger than thesucceeding ground signals. Radar experience indicates that the specification ofwhat curve the pattern should follow isless important than therequirement that thepattern besmooth. 
 405–408. 170. H. 
 26. tlouls. R. 
 This approach is particularly useful against pulsed ECM, spot noise, and nonuniform barrage noise; its effectiveness depends . primarily on the extent of the radar agile bandwidth and the acquisition speed and frequency tracking of an "intelligent" jammer. A technique suited to this purpose is referred to as automatic frequency selection (AFS).64'66 Another method to reduce the effect of main-beam noise jamming is to in- crease the transmitter frequency (as an alternative means to the use of a larger antenna) in order to narrow the antenna's beamwidth. 
 TO 
 IX.Fannin. B.M..andK.H.Jehn:AStudyofRadarElevation-angle ErrorsDuetoAtmospheric Rerraction. IRETrailS..vol.AP-5.pp.71-77.January, 1957. 
 ULAR MODEL  THE TWO 
 This allows for a very high-quality  transistor that can be made with useful gain beyond W band. Higher mobility and  electron velocity can be engineered by increasing the percentage content of indium  in the channel of the FET. This can be accomplished up to a point, where beyond  approximately 25% indium content, the lattice strain differential results in degrading  performance and reliability. 
 G.: Constant False Alarm Rate Processing in Search Radars, Proc. IEEE Int. Radar Conf., pp. 
 Eachtimetheradarbeamscanspastthe target.itscoordinates areobtained.Ifthechangeintargetcoordinates fromscantoscanisnot ((10large.itispossible toreconstruct thetrackofthetargetfromthesampled data.Thismay heaccomplished byproviding thePPI-scope operator withagreasepenciltomarkthetarget pipsonthefaceofthescope.Alinejoiningthosepipsthatcorrespond tothesametarget provides thetargettrack.Whenthetrarticissodensethatoperators cannotmaintain pace withtheinformation available fromtheradar,thetargettrajectory datamaybeprocessed automatically inadigitalcomputer. Theavailability ofsmall,inexpensive minicomputers has madeitpractical toobtaintargettracks,notjusttargetdetections, fromasurveillance radar. Suchprocessing isusuallycalledADT(automatic detection andtrack).WhentheOlltputs frommorethanoneradarareautomatically combined toprovidetargettracks,theprocessing iscalledADIT(automatic detection andintegrated track)orIADT(integrated ADT). 
 PHASE AND QUADRATURE COMPONENTS )  1  THROUGH THE !$ CONVERTER  EITHER USING A PAIR OF PHASE DETECTORS OR THROUGH DIRECT SAMPLING AS DISCUSSED IN 3ECTION  4HE IN 
 BAND SPURIOUS SIGNALS CAN ALSO RESULT FROM POWER SUPPLY AND MODULATOR INSTABILITIES 2EDUCTION OF 3PECTRUM !MPLITUDE %XCEEDING SIN  X X 4HE SPECTRUM OF A  PERFECTLY RECTANGULAR PULSE HAS THE FAMILIAR SIN  X X FORM  WHERE  X IS O F O  
 However, some questions ofimportance remain with regard toground clutter. OnthePPI ofa10-cm MT1 system operating near Boston ataPRF of 300, many thousands ofuncanceled targets have been observed under conditions that make anexplanation difficult. These targets, which might possibly bebirds, have been noticed toincrease innumber just after sunset. 
 I RE, vol. 38, pp. 1422~ 1428, December, l 950. 
 The leading edge ofthe Eagle vane (Fig. 9“18)isaradome made of two Fiberglas walls with occasional ribs asspacers. While the airfoil section isinitself oflow drag, theattachment totheplane increases the drag until itisalmost ashigh asthat forthe cylindrical radome. 
 low-noise amrliftcr. oulrut filler. circulal<H. 
 SUBMATRIX3TEADY 
 Fante, “SAR imaging of moving targets,” IEEE Transactions  on Aerospace and Electronic Systems , vol. 35, no. 1, pp. 
 Few natural grounds are truly homogeneous in composition over very wide  areas. Descriptions of their detailed shape must be simplified if they are to be handled  analytically, although computers permit the use of true descriptions. Very few sur - faces have ever been measured to the precision appropriate for centimeter-wavelength  radars; even for these, there is no assurance that scattering boundaries do not exist  within a skin depth beneath the surface. 
   (AMMING  
 59.Baars,J.W.M.:TheMeasurement ofLargeAntennas withCosmicRadioSources," IEEETrans., vol.AP-21,pp.461-474, July,1973. 60.StaeHn,D.H.:PassiveRemoteSensingatMicrowave Wavelengths, Proc.IEEE,vol.57,pp.427-439, April,1969. 61.Greene,1.:Antenna NoiseTemperature, AILAdvertisement, Proc.IRE,vol.46,p.2a,May,1958. 
 The technique of using a long, modulated pulse to obtain the resolution of a short  pulse, but with the energy of a long pulse, is known as pulse compression. Continuous  waveforms (CW) also can be used by taking advantage of the doppler frequency shift to  separate the received echo from the transmitted signal and the echoes from stationary clutter.  Unmodulated CW waveforms do not measure range, but a range measurement can be made  by applying either frequency- or phase-modulation. 
 279-285.  13. U rkowitz, H.: Analysis and Synthesis of Delay Line Periodic Filters, IRE Trans., vol. 
 Rept. no. 349, Mar. 
 H. Sheppard, “AN/SPY-1 phased array antenna,” Microwave J ., vol. 17,  pp. 
 Itisnotusuallyconvenient toobtaintheradarcrosssectionofaircraftbymounting the full-sizeaircraftonarotating table.Measurements canbeobtained withscalemodelsona patternrange.29Anexample ofsuchmodelmeasurements isgivenbythedashedcurvesin Fig.2.17.Ifcareistakenintheconstruction ofthemodelandinthepattern-range instrumentation. itispossible toachievereasonably representative measurements. Theradarcrosssectionofanaircraftcanalsobeobtained bycomputation.l7Thetargetis brokenupintoanumber ofsimplegeometrical shapes,thecontribution ofeach(taking. 
 BASED 3!24S HAVE NOW BEEN PROPOSED 4HESE MAY EVENTUALLY REPLACE RADAR 
 for Swerling models, 47-49  Simultaneous lobing, 160  Sinusoidal modulation, in FM radar, 88-91  Smith chart, 196  Snake feed, 301  Snow, scattering from, 502  Snow-covered terrain, 490-491  Solar noise, 463  Sole, CFA, 209  Solid-state limiters, 363-364  Solid-state transmitters, 216220  Space feeds, 308-309  Space-frame radome, 265-266  SPASUR, 80  Radialvelocitydirection, inCWradar,78-79 Radiation hazards, 465-466 Radiation intensity, 224 Radiation pattern: antenna, 224,228-235 array,280-282 Radomes, 264-270 Rain: andradomes, 269-270 scattering from,500-502 atmillimeter waves,564 Random errors: inarrayantennas, 318-322 inreflector antennas, 262-264 Rangeaccuracy, 401-407 Rangeambiguities, 53-54 Range-gate stealer,551 Range-gated dopplerfilters,117-119 Rangemeasurement, inCWradar,95-98 Rangeresolution, andautomatic detection, 186 Rangetracking, 176-177 Rasterscan,178 Rayleigh probability densityfunction, 22-23,47 andseaecho,478 Rayleigh region,33-34 Rayleigh scattering, 499 Rear-port display,358-359 Receiver noise,18-19 Receiver protector, 362-363 Receivers, 343-353 Recirculating-delay-Iine integrator, 390-392 Recursive filter,113 Reference gain,MTI,111 Reflectarray, 309 Reflection coefficient, ofsea,445 Reflective-array compressor, 425 Refraction, 447-450, 455-456 Refractivity: 448 Refractometer, 455 Reggia-Spencer phaseshifter,291-293 Repeater jamming, 551-552 Resolution, ofSAR,518-519 Resonance region,inscattering, 34 Resonant-charging, modulator, 215 Resonant frequency, oftracking antennas, 179 RFkeying,ofCFA,211 Riceprobability densityfunction, 26,50 Riekediagram, magnetron, 195-198 Ring-bar TWT,206 Ringechoes,512 Ring-loop TWT,207 Ringtuner,magnetron, 200 Rising-sun magnetron, 193,194 Rod,radarcrosssectionof,34-35INDEX579 Rollstabilization, 271 Rotodome, 268 Sampleandhold,156 SAR,517-529 SAWdelaylines,424-426 SCAMP, 163 Scanwithcompensation, 164 Scanconverter, 358 Scanning-feed reflector antennas, 244-248 Schottky-barrier diodes,347 Schwartz inequality, 372 Seaclutter,474-489 HFradar,533-535 atmillimeter waves,563-564 Seastate,475 Second-time-around echo,3 inMTI,117 Self-screening range,550 Semiactive homing, 80 Sensitivity timecontrol(seeSTC) Sequential detection, 381-382 inarrayradar,324 Sequentiallobing, 153-154 Sequential observer, 380-382 Series-fed array,285 Servonoise,170 Servosystem,178-179 Shadowgrid,203 Ships,radarcrosssectionof,42-45 Shortpulse,applications of,421 Sideband superheterodyne receiver, 84-85 Sidelobecanceler, 333,549 Sidelobes, antenna, 227-228 Sidelobes, FMpulsecompression, 426-427 Sidelooking radar,517 Sigmazero,471 Signalmanagement, inarrayradar,324 Signal-to-noise ratio: fordetection, 28,48 .forSwerling models,47-49 Simultaneous lobing,160 Sinusoidal modulation, inFMradar,88-91 Smithchart,196 Snakefeed,301 Snow,scattering from,S02 Snow-covered terrain,490-491 Solarnoise,463 Sole,CFA,209 Solid-state limiters, 363-364 Solid-state transmitters, 216-220 Space ~eds,308-309 Space-frame radome,265-266 SPASUR,80. 580 INDEX  Speckle, in SAR, 528  Speed gate, 8 1  Sphere, radar cross section of, 33-34  Spherical reflectors, 245-246  Spike leakage, and diode burnout, 350  Spikes, and sea clutter, 477  Spin-tuned magnetron, 199  Spiral scan, 178  Split range gate, 176-177  Spotlight mode, SAR, 527  Spread spectrum, 434  Squint angle, 155, 158-159  Squint mode, SAR, 527  Stabilization of antennas, 270-273  Stacked-beam 3D radar, 543-544  Staggered prf, in MTI, 114-1 17  Stalo, 105  Standard deviation, 21  Standard temperature, 19  STC :  in ARSR-3, 540  and duplexer, 366  and logarithmic receiver, 507  and sea clutter, 488  and shaped beams, 261  Storage tube, 357-358  MTI, 126  Straddling loss, 61  Straps, magnetron, 193  Stretch pulse compression, 432  Structure constant, 51 1  Subarrays, 309-310  Subclutter visibility, 129-130  Submillimeter wavelengths, 564  Surface acoustic wave delay lines, 424-426  Surface duct, 451,453-455  Surface, for reflector antennas, 239-240  Surveillance radar range equation, 64  Swerling cross section models, 46-49  Switched-line phase shifter, 288  Synthesis of antenna patterns, 254-258  Synthetic aperture radar, 517-529  Synthetic video displays, 359  System losses, 56-61  System noise figure, 346  System noise temperature, 345, 463-465  Systematic errors :  antenna, 262  tracking, 180  TACCAR, 142  Tapped-delay-line integrator, 390  Target classification, 434-438  Taylor aperture illumination, 257-258 Tellurometer, 97  Thermal noise, 18  Thin-wall radome, 267  Thinned arrays, 309, 319, 331-332  Three-axis mount, 271  3D radar, 301, 541, 544  Three-pulse canceler, 109- 1 10  Threshold detection, 16-17, 27  Thumbtack ambiguity diagram, 418-419  Time-difference height finding, 546-547  Time-frequency coded waveform, 43 1  Tolerances, in lenses, 253-254  Torque fins, antenna, 269  TR tube, 361-362  Track initiation and maintenance, 325-326  Track-while-scan radar, 152-1 53, 183  sector scanning, 248  Tracking, automatic, 153, 183- 186, 392  Tracking illuminator, CW, 73, 81  Tracking radar, 152-186  angular accuracy, 167- 172  conical scan, 155-159, 182- 183  conopulse, 164  glint, 168-172  lobe switching, 153  low-angle, 172- 176  monopulse, 160-167, 181-183,435  off-axis tracking, 174  on-axis tracking, 180-18 1  scan with compensation, 164  sequential lobing, 153-154  simultaneous lobing, 160  Tracking with surveillance radar, 183-186  Transient response, in MTI, 113-1 14  Transistors:  low noise, 351, 352  power, 2 17  Transmitter noise, 73-74  Transmitter power, 52-53  Transmitters, 190-220  Amplitron, 209  crossed-field amplifiers, 208-2 13  grid-controlled tubes, 2 1 3  klystron, 200-205  magnetron, 192-200  modulators, 2 14-2 16  solid-state, 2 16-220  traveling-wave tube, 206-208  Twystron, 208  Transreflector, 242  Transversal filter, 110- 1 14  Traveling-wave tube phase shifter, 297  Traveling-wave tubes, 206-208  Triangular element spacing, 333-334  580INDEX Speckle, inSAR,528 Speedgate,81 Sphere,radarcmsssection of,33-34 Spherical reflectors, 245-246 Spikeleakage,anddiodeburnout, 350 Spikes,andseaclutter,477 Spin-tuned magnetron, 199 Spiralscan,178 Splitrangegate,176-177 Spotlight mode,SAR,527 Spreadspectrum, 434 Squintangle,155,158-159 Squintmode,SAR,527 Stabilization ofantennas, 270-273 Stacked-beam 3Dradar,543-544 Staggered prf,inMTI,114-117 Stalo,105 Standard deviation, 21 Standard temperature, 19 STC: inARSR-3, 540 andduplexer, 366 andlogarithmic receiver, 507 andseaclutter,488 andshapedbeams,261 Storagetube,357-358 MTI,126 Straddling loss,61 Straps,magnetron, 193 Stretchpulsecompression, 432 Structure constant, 511 Subarrays, 309-310 Subclutter visibility, 129-130 SubmiJIimeter wavelengths, 564 Surfaceacoustic wavedelaylines,424-426 Surfaceduct,451,453-455 Surface,forreflector antennas, 239-240 Surveillance radarrangeequation, 64 Swerling crosssectionmodels,46-49 Switched-line phaseshifter,288 Synthesis ofantennapatterns, 254-258 Synthetic aperture radar,517-529 Synthetic videodisplays, 359 Systemlosses,56-61 Systemnoisefigure,346 Systemnoisetemperature, 345,463-465 Systematic errors: antenna, 262 tracking, 180 TACCAR,142 Tapped-delay-line integrator, 390 Targetclassification, 434-438 Tayloraperture iJlumination, 257-258Tellurometer, 97 Thermal noise,18 Thin.,.wall radome, 267 Thinned arrays,309,319,331-332 Three-axis mount,271 3Dradar,301,541,544 Three-pulse canceler, 109-110 Threshold detection, 16-17,27 Thumbtack ambiguity diagram, 418-419 Time-difference heightfinding,546-547 Time-frequency codedwaveform, 431 Tolerances, inlenses,253-254 Torquefins,antenna, 269 TRtube,361-362 , Trackinitiation andmaintenance, 325-326 Track-while-scan radar,152-153, 183 sectorscanning, 248 Tracking, automatic, 153,183-186, 392 Tracking illuminator, CW,73,~1 Tracking radar,152-186 angularaccuracy, 167-172 conicalscan,155-159, 182-183 conopulse, 164 glint,168-172 lobeswitching, 153 low-angle, 172-176 monopulse,160-167, 181-183,435 off-axistracking, 174 on-axistracking, 180-181 scanwithcompensation, 164 sequential lobing,153-154 simultaneous lobing,160 ,Tracking withsurveillance radar,183-186 Transient response, inMTI,113-114 Transistors: lownoise,351,352 power,217 Transmitter noise,73-74 Transmitter power,52-53 Transmitters, 190-220 Amplitron, 209 crossed-field amplifiers, 208-213 grid-controlled tubes,213 klystron, 200-205 magnetron, 192-200 modulators, 214-216 solid-state, 216-220 traveling-wave tube,206-208 Twystron, 208 TransretJector, 242 Transversal filter,110-114 Traveling-wave tubephaseshifter,297 Traveling-wave tubes,206-208 Triangular elementspacing, 333-334. INDEX 581  True-hearing display, 27 1  True time delays. 
 POLE FILTERED WHITE NOISE RATHER THAN A WEIGHTED SUM OF SINUSOIDS ACCORDING TO THE &OURIER MODEL  -ULTIPLE SIGNALS AND GROUND CLUTTER MAY BE RESOLVED THE SAME  AS USING &OURIER ESTIMATORS 4HESE SHORT DWELL TIME !2 SPECTRA MAY THEN BE USED TO ESTIMATE WEATHER SPECTRAL MOMENTS THE SAME AS THE &OURIER DATA MODEL SPECTRUM ESTI 
 Alternatively, if the transmit beam scan rate and the pulse repetition fre- quency (PRF) are uniform, the receive site can estimate these parameters as the transmit beam passes by the receive site.127 FIG. 25.11 Pulse chasing for the single-beam, continuous-scan case. The receive beam-scanning rate must be at the transmitter's pulse propagation rate, modified by the usual geometric conditions. 
 Therefore, in this paper, the minimum-entropy autofocusing is applied to mitigate the scintillation effect instead of phase gradient autofocusing method. Since the spatial variation of scintillation phase screen, the autofocusing performance is limited in strong scintillation conditions. The scintillation parameters are set as CkL=1033and p=3. 
 TION .ORMAL TARGET MOTION WILL RESULT IN DIFFERENT DOPPLER SHIFTS FOR EACH MAJOR SCAT 
 )43   53 'OVT 0RINTING /FFICE  7ASHINGTON  $#    3 !YASLI  h3%+% ! COMPUTER MODEL FOR LOW ALTITUDE RADAR P ROPAGATION OVER IRREGULAR TERRAIN v  )%%% 4RANSACTIONS ON !NTENNAS AND 0ROPAGATION   VOL !0 
 259-263.  27. Sommer. 
 The underground strata below the Rongguite and Anlite Bridges are mainly argillaceous siltstone and silty mudstone. From the longitudinal distribution characteristics of the route, the soft soil layer in the north of Rongguite Bridge is mainly composed of continuously distributed mucky clay, with a thickness of 12.93–19.50 m. In the section between Ronguite Bridge and Xiti Fouth Road, the main components of the soft soil are mucky clay and silty clay, with a thickness of 6.46–9.90 m. 
 WNk denotes a phase shift of 2 kπ/N. These weights are  often referred to as twiddle factors . Figure 25.43 shows the phase shifts associated  with various twiddle factors.2 Note that the 8-point FFT consists of three stages. 
 RADAR HANDBOOK Editor in Chief MERRILL I. 
 9. Oliver, B. M.: Automatic Volume Control as a Feedback Problem, Proc. 
 Thesidelobes inthetime-frequency planeoftheambiguity diagram areusually largerthandesiredforgooddoppler resolution without ambiguity. Although theambiguity diagram ofthephase-coded pulsehasanarrowspike,thewideplateaumeansthattherecanbe alargeundesirable response fromdistributed clutterthatextends inboththerangeandthe dopplerdomain, andtheresolution performance willbepoorinadense-target environment or whenasmalltargetistobeseeninthepresence ofmuchstronger echoes.. A different phase-coded sequence can be assigned to each radar so that a number of  radars can share the same spectrum. 
 Theeffectoficeontheelectrical characteristics ofameshreflecting surfaceistwofold. III Ontheonehand,icewhichfillsapartofthespacebetween themeshconductors mayhe considered adielectric. Adielectric aroundthewiresisequivalent toashortening ofthe wavelength incident onthemesh.Thespacing between wiresappears wider,ekctrically, causing thetransmission coefficient ofthesurfacetoincrease. 
 The azimuth resolution  and accuracy obtained by tlie 1.25" beatnwidth is said to be 2" and 0.2", re~pectively.'~ Tlie  antenna cati he lio~lsed in a 17.4 tn (57 ft) diameter rigid geodesic-radome.  The AKSR-3 antenna generates two beams sliglitly displaced in elevation for the purpose  of reducing the eclioes from high-speed surface clutter, such as from automobiles and trucks.  These clutter echoes cati be large enougll and have a sufficiently high doppler frequency shift  (HilER RADAR TOPICS539 vehicleonwhichtheradariscarricd; rcliability (meantimehetween failures). 
 338 INTRODUCTION TO RADAR SYSTEMS  12. Hansen, R. C.: .. 
 Lin, “Scanning spaceborne synthetic aperture radar with  integrated radiometer,” IEEE Transactions on Aerospace and Electronic Systems , vol. AES-17,  pp. 410–421, 1981. 
 MATELY  §S  AND A ,&- SLOPE  "4 y  -(Z §S      -(Z§S 4HE RANGE  WINDOW WIDTH FOR THE  -(Z PROCESSING BANDWIDTH IS    $RC" "4MS P  r   M M-(Z -(ZSM  -ILLIMETER  7AVE 2ADAR 4HE STRETCH PROCESSING IMPLEMENTATION FOR THE -ILLIMETER  7AVE RADAR --7  LOCATED AT +WAJALEIN !TOLL IS DESCRIBED BY !BOUZAHARA AND  !VENT 4HE --7 RADAR OPERATES AT A CARRIER FREQUENCY OF  '(Z USING WAVEFORMS  WITH A MAXIMUM SWEPT BANDWIDTH OF  -(Z AND PULSEWIDTH OF  §S 4HE ,&- SLOPE FOR THE TRANSMIT WAVEFORM IS   AMM     " 4-(Z  S-(ZS  4HE  STRETCH PROCESSING BANDWIDTH IS  "P    -(Z 4HE WIDTH OF THE STRETCH PROCESSING  TIME WINDOW IS    $T  -(Z -(Z SSMM  4HE  REFERENCE WAVEFORM PULSEWIDTH IS  42          §S TO AVOID A LOSS IN 3.2  FOR TARGETS AT THE EDGES OF THE RANGE WINDOW 4HE SWEPT BANDWIDTH OF THE REFERENCE  WAVEFORM AND THE RANGE WINDOW WIDTH ARE   "2 r  -(Z S  S -(ZMM     $$RCT   r  M S  S MMM   4HE  
 SHIP CRUISE MISSILE !3#-  THREATS AND SUPPORT FIRE 
 7.3.2 Predicted performance of ASV Mks III, VI and VII The key parameters that in ﬂuenced detection range performance are listed in table 7.5, using modern SI units. Direct comparisons between ASV Mk. III and ASV Mk. 
 CODED OR GRAYSCALE PIXEL FORMAT (ERE  THE TARGET OUTLINE HAS BEEN SUPER 
 BEAM NOISE 
 When no other input  data is available, the IREPS utilizes a stored library or historic refractivity and climatology  statistics as a runction of the latitude, longitude, season, and time of day. When historic data  is used the output is a prediction or propagation performance in probabilistic terms. Also  stored are the necessary system parameters for the various electromagnetic systems whose  predicted propagation performance is desired. 
 On the basis of this description of signal and clutter, it has been shown18 that the opti - mum doppler filter will have weights given by  w sC1 OPT= ⋅−Φ (2.34)FIGURE 2.23  Approximate MTI improvement factor limitation due to pulse-to-pulse repetition-period  staggering and scanning (all canceler figurations): I(dB) = 20 log [2.5 n/ (g  − 1)]; g  = maximum period/ minimum period ch02.indd   28 12/20/07   1:44:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 R.F.:ASolution totheProblem ofRapidScanning forRadarAntennas. J.Appl.Phys.. vol.19.PP860862, September. 
 23.3)  and is detailed in Willis.1 On occasion, the included angles qT' and qR' are used to  define transmitter and receiver look angles in the bistatic triangle, such that qT' + qR' +  b = 180º. In this case, qT' = 90º – qT and qR' = 90º + qR can be used to transform north- referenced equations into included-angle equations. Plots of bistatic clutter data use a  separate and quite arcane coordinate system, which is defined in Section 23.8. 
 SEC. 1021 THERESONANT SYSTEM 327. 328 THE MAGNETRON AND THE PULSER [SEC. 
 The most common is the rigid space-frame, Fig. 7.29, which consists of a three­ dimensional lattice of primary load-bearing members enclosed with thin dielectric panels. The  panels can be very thin, even for large-diameter radomes, since they are not required to carry  main loads or stresses. 
 The ﬁrst- and second-order spatial variance errors of the Doppler rate and the ﬁrst-order spatial variance error of the derivative of the Doppler rate should be estimated and compensated. 55. Sensors 2019 ,19, 213 Use the ﬁtting coefﬁcients in (13) to correct the corresponding Doppler parameters in the high-squint airborne SAR imaging algorithm [ 6] so as to achieve the focus improved image. 
 CHAPTER  TWELVE  PROPAGATION OF RADAR WAVES  12.1 INTRODUCTION  Tlie propagation of radar waves is affected by the earth's surface and its atmosphere. Complete  analysis or prediction of radar performance must take into account propagation phenomena  sit~cc tilost radars do not opcratc ill " frcc space" as was assumed in the ideal formulation of  the radar equation in Chaps. 1 arid 2. 
 !DAPTIVE !RRAY 0ROCESSING v  )%% )NT #ONF 2ADARn    #ONF 0UB   ,ONDON  /CTOBER n    PP n  , 7 $ICKEN  h4HE USE OF NULL STEERING IN SUPPRESSING MAIN BEAM INTERFERENCE v  )%% )NT #ONF  2ADARn  #ONF 0UB   ,ONDON  /CTOBER n    PP n  7 & 'ABRIEL  h3PECTRAL ANALYSIS AND ADAPTIVE ARRAY SUPERRESOLUTION TECHNIQUES v  0ROC )%%%   VOL   PP n  *UNE   5 .ICKEL  h&AST SUBSPACE METHODS FOR RADAR APPLICATIONS v IN  !DVANCED 3IGNAL 0ROCESSING  !LGORITHMS  !RCHITECTURES AND )MPLEMENTATION 6))   & 4 ,UK ED   30)% 0ROC 3ERIES VOL   #ONF 2EC 30)% 3AN $IEGO    PP n  5 .ICKEL  h!SPECTS OF IMPLEMENTING SUPERRESOLUTION METHODS INTO PHASED ARRAY RADAR v  )NT  *OURNAL %LECTRONICS AND #OMMUNICATIONS !%â   VOL   NO   PP n    5 .ICKEL  h3POTLIGHT -53)# 3UPERRESOLUTION WITH SUB 
 CONVOLUTION OF THE PREDETECTION SPECTRUM /NLY THE PART THAT PASSES THE LOW 
 77.6 DYNAMIC-RANGE AND STABILITY REQUIREMENTS Dynamic Range. Dynamic range as discussed here is the linear region above thermal noise over which the receiver and signal processor operate before any saturation (clipping) or gain limiting occurs. If saturations occur, . 
 D" WIDTHv 4O OBTAIN FINE RESOLUTION IN EITHER RANGE OR CROSSRANGE  A &OURIER TRANSFORM &4  IS  PERFORMED ON A SET OF COLLECTED DATA 3INCE ALL DATA SAMPLES HAVE ESSENTIALLY THE SAME MAGNITUDE  FOR EITHER RANGE OR CROSSRANGE WE ESSENTIALLY PERFORM A &4 ON A RECT 
 This criterion was first formulated  in a limited-distribution report by Erner~on.~ Tfie ratio I, was called in theearly literature the  refcretrce gclit~, but it is now called the intprovernent factor for clutter. It is independent of the  target velocity atid depends only on the weights wi, the autocorrelation function (or power  spectrum) describing the clutter, arid the number of pulses. For the two-pulse canceler (a single  delay lirie). 
 20. T. Felhauer, “Design and analysis of new P(n,k) polyphase pulse compression codes,” IEEE  Transactions on Aerospace and Electronics Systems , vol. 
 The phase advance between the first pair of pulses (first and  second pulse for the three-pulse MTI) received by the sum pattern Σ is  24 21ηπ λθω ω= −  +TVTVp xr p yrsin s in cos2T Tp 2−      cos2θ  (3.21) and the phase advance between the second pair of pulses (second and third pulse for  the three-pulse MTI) is  24 22ηπ λθω ω= +  +TVTVp xr p yrsin s in cos2T Tp 2−      cos2θ  (3.22) FIGURE 3.16  Phasor diagram for simultaneous scanning and motion   compensation ch03.indd   18 12/15/07   6:03:20 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 
 When the system requirements permit a time sharing of the doppler frequency  range, the bank of doppler filters may be replaced by a single narrowband tunable filter which  searches in frequency over the band of expected doppler frequencies until a signal is found. 78 INTRODUCTION TO RADAR SYSTEMS  After detecting and recognizing the signal, the filter may be programmed to continue its search  in frequency for additional signals. One of the techniques for accomplishing this is similar 10  the tracking speed-gate mentioned in Sec. 
 Adaptive  antennas require some a priori knowledge of the desired signal, such as its direction,  waveform, or statistical properties.  ff all the elements of an adaptive phased-array antenna have a separate adaptive control  loop, it is called a .fitlly adapti11e array. The adaption process is based on the application of  some criterion such as the minimization of the mean-square error or the maximization of the  signal-to-noise ratio. 
 HORIZON RANGES  ALTHOUGH MODEST  HAS BEEN EXPLOITED IN SOME DUAL 
 1924-1931, November, 1968.  24. Temme, D. 
 410 416,  July, 1962.  89. Moody, H. 
 9  RECEIVER TESTS ................................ ................................ ............. 
          
 2.409.944, issued Oct. 22, 1946.  69. 
 TRONIC SCANNING IS DISCUSSED FURTHER IN 3ECTION  !N ESPECIALLY COMMON MULTIPLE BEAM DESIGN IS THE MONOPULSE ANTENNA IN &IGURE  E  USED FOR ANGLE DETERMINATION  ON A SINGLE PULSE  AS THE NAME IMPLIES )N THIS INSTANCE  THE SECOND BEAM IS NORMALLY A DIFFERENCE BEAM WITH ITS NULL AT THE PEAK OF THE FIRST BEAM &)'52%   #OMMON REFLECTOR ANTENNA TYPES  A  PARABOLOID  B  PARABOLIC CYLINDER  C  SHAPED   D  STACKED BEAM  E  MONOPULSE  AND F  #ASSEGRAIN.   2%&,%#4/2 !.4%..!3   £Ó°£Ç -ULTIPLE REFLECTOR SYSTEMS  TYPIFIED BY THE #ASSEGRAIN ANTENNA SHOWN IN  &IGURE F  OFFER ONE MORE DEGREE OF FLEXIBILITY BY SHAPING THE PRIMARY BEAM AND OR ALLOWING THE FEED SYSTEM TO BE CONVENIENTLY LOCATED BEHIND THE MAIN REFLECTOR 4HE SYMMETRICAL ARRANGEMENT SHOWN HAS SIGNIFICANT BLOCKAGE  BUT OFFSET GEOMETRIES MITIGATE FEED BLOCKAGE )N MODERN REFLECTOR ANTENNA DESIGN  COMBINATIONS AND VARIATIONS OF THESE BASIC  TYPES ARE WIDESPREAD HOWEVER  DESIGN GOALS GENERALLY STRESS BEAM GAINS   SHAPES   LOCATIONS   ETC  WHILE STIPULATING MINIMAL LOSSES AND LOW SIDELOBE LEVELS 0ARABOLOIDAL 2EFLECTOR !NTENNAS  4HE THEORY AND DESIGN OF PARABOLOIDAL REFLEC 
 FILTERING PARAMETER FTRACK  GSTRACK Q4 M     "ECAUSE THE RADAR MEASUREMENT ACCURACY  AS REPRESENTED BY THE COVARIANCE MATRIX    AND THE TIME BETWEEN DETECTION OPPORTUNITIES   4  ARE PARAMETERS OF THE RADAR DESIGN  ITSELF  THE SELECTION OF  1TK  IS THE DEGREE OF FREEDOM AVAILABLE TO THE TRACKING FILTER  DESIGN 4ABLE  SUMMARIZES THE METHODS FOR TUNING THE +ALMAN FILTER. 
 STATE TRANSMIT TERSHIGH POWER MUST  BE ACHIEVED BY COMBINING THE OUTPUTS OF LOWER 
 Typical values for a° and TI taken from the same reference are given in Table 15.2. Because of the imprecision in predicting a° and TJ, these equations do not include an antenna beam-shape factor. For the measurement of the reflectivity of rain, references on radar meteorology present more precise equations.9 In addition to distributed clutter targets, there are many targets that appear as points, such as radio towers, water tanks, and buildings. 
 20.5, some of which have a substantial impact on the fundamental monopulse accuracy performance. In each of these implementations, returns from a single transmission are received in si- multaneously formed sum and difference beams and processed coherently. In the full-vector monopulse of Fig. 
 NATED BY THE SIDE OF THE MAIN BEAM OR THE MINOR LOBES  THEIR SIGNALS MAY CONTRIBUTE SO MUCH TO THE RETURN THAT IT IS SIGNIFICANTLY CHANGED 3INCE THIS CHANGED SIGNAL IS CHARGED TO THE DIRECTION OF THE MAJOR LOBE BY THE DATA REDUCTION PROCESS  THE RESULTING VALUE FOR  R   IS IN ERROR 2ESPONSES AT VERTICAL INCIDENCE FREQUENTLY CAUSE TROUBLE  FOR  VERTICAL 
 Using higher-order terms gives an im- proved correction signal. FIG. 16.16 Phaser diagram for simultaneous scanning and motion com- pensation. 
 Automatic AngleTracking. -Shortcomings ofthe SCR-268 asafire- control position finder arose mainly from the use ofarelatively long wavelength which resulted inbroad beams from antennas ofany reason- able size. When microwave radar became practicable with the develop- ment ofthe cavity magnetron, one ofthe immediate applications ofthe new technique was anantiaircraft position finder. 
 L. B. Wetzel, “On the origin of long-period features in low-angle sea backscatter,” Radio Sci .,   vol. 
 The repetition rate could bereduced to12.5 pps when iono- spheric disturbances were unusually troublesome. The pulse width could bevaried from 6toabout 25~sec and the receiver bandwidth could bechanged from 50to500 kc/see. Innormal operation the pulse length was about 12~sec and the bandwidth 150 kc/see, The final design made use ofcontinuously evacuated transmit- ting tubes with uncoated tungsten filaments, whose c-wpower output was about 80kw. 
 139.Steinberg, B.D.:ThePeakSidelobe ofthePhasedArrayHavingRandomly ~ocated Elements, IEEE TraIlS.,vol.AP-20,pp.129-136, March,1972. 140.Skolnik, M.I.:Resolution ofAngular Ambiguities inRadarArrayAntennas withWidely-Spaced Elements andGrating Lobes,IEEETrans.,vol.AP-IO,pp.351-352, May,1962. 141.Goto,N.;andD.K.Cheng: PhaseShifterThinning andSidelobe Reduction forLargePhased Arrays,IEEETrans.,vol.AP-24,pp.139-143, March,1976. 
 Peterson, W. W., T. G. 
 output  Figure 10.9 Pulse integrator using tapped delay line. Loop goin k < 1  l  Input --~------1 Deloy line f _j  lnteqroled  output  (a)  Deloy line  (cl lnlegrated  oulpul. DETECTION OF RADAR SIGNALS IN NOISE 391  Delay line Inlegroted  output  ,_,__--; Delay line  (b)  -----< l<.11---- Figure IO. 
 The RCS levels shown in the scale model Boeing 737 patterns of Fig. 11.16 are those at the mea- surement frequency. To obtain the corresponding full-scale values, one must add 23.5 dB (10 log 225); the full-scale frequency is one-fifteenth of the measurement frequency in this case, or 667 MHz. 
 16•24·25 The Taylor weighting with ii = 8 means the  peaks of the first 7 sidelobes (ii -1) are designed to be equal, after which they fall off as 1/t.  The Dolph-Chebyshev weighting theoretically results in all sidelobes being equal. It is of  academic interest only, since it is unrealizable. 
 ENT TIMES 4HIS REQUIREMENT IS READILY SATISFIED FOR SHORT INTEROPPORTUNITY INTERVALS  SUCH .   30!#% 
 BANDWIDTH 2& AMPLIFIER  ITS DYNAMIC RANGE MAY BE SEVERELY RESTRICTED DUE TO WIDEBAND NOISE INTERFERENCE 7HEN LOW 
 Historically, it has always been feasible to obtain the extremely low ripple lev- els desired for MTI systems, limited only by inherent noise levels (including jitter and starting-time noise) in the tubes. For pulse compression systems, the neces- sary freedom from ringing during the pulse length has been fairly easy to achieve with hard-tube modulators and difficult to achieve with line-type modulators, with either linear-beam tubes or CFAs.36 Life. Linear-beam tubes and CFAs have both shown the feasibility of long life (over 40,000 h in some cases), but both have also shown very short life when the wrong tube-design compromises were made, when development problems re- mained, or when tubes were misapplied or carelessly handled in the field. 
 It called attention tothe revolutionary usefulness ofradar inmodern air warfare, but atthe same time ittended tofreeze operational thinking ccmcerning radar along lines ofthe static defense which was allthat the CH stations could provide. The main Chain operated atfrequencies between 22and 28Me/see. Inspite ofthe disadvantages inevitable inany system operating onso low afrequency, the choice was made deliberately after consideration of thetubes and techniques available atthetime. 
 Thus, in the vicinity of broadside (00 ::'.:!'. 0), the bandwidth available for pulse com­ pression is J/8 ::'.:!'. 1/t I>. 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 25.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 Decimation Filters.  As mentioned previously, the complexity and cost of a signal  processor, in terms of the amount of system resources required to implement it, gener - ally varies linearly with the data sample rate. 
 65,   pp. 825–837, 1960. 59. 
 We shall consider here the antenna pattern  produced hy a two-dimensional distribution across a circular aperture. The polar coordinates  {r. 0) are used to describe the aperture distribution A(r, 0), where r is the radial distance from  the center of the circular aperture, and O is the angle measured in the plane of the aperture with  respect to a reference. 
 Afew minor points remain tobe considered. First, the explanation has assumed that the bandwidth is large enough topass square waves without distortion. Actually, the operation issubstantially the same when only afew harmonics ofj,are passed. 
 Consider the scattering from a relatively" simple" complex target consisting of two equal,  isotropic objects (such as spheres) separated a distance I (Fig. 2.14). By isotropic scattering is  meant that the radar cross section of each object is independent of the viewing aspect. 
 Smith, “Geometrical shadowing of the random rough surface,” IEEE Trans ., vol. AP-15,   pp. 668–671, 1967. 
 TIC FRAMEWORK  -OST RADARS IMPLEMENT TARGET TRACKING AS A SEPARATE STAGE THAT OPERATES  ON THE CANDIDATE TARGETS AFTER THEY HAVE BEEN REGISTERED  INITIATING  UPDATING  OR TERMINAT 
 BOARD SENSOR FUSION  A TOTAL AIR AND GROUND PICTURE CAN BE PRESENTED IN THE COCKPIT 4HIS PICTURE CAN BE A COMBINATION OF DATA FROM  &)'52%  ! 
 Real airborne experiments have demonstrated that the proposed KA-DBS algorithm performs well with short dwell time. Author Contributions: Conceptualization, H.C., Z.W. and J.L.; Methodology, H.C., Z.W. 
 High-efficiency GaAs solar cells have demonstrated efficiencies of 18 percent.57 With the addition of other subsystems, including panels, rotary joints, slip rings, battery, power control, and distribution equipment, the specific power density of the prime power system is on the order of 13 to 24 W/kg. Solar-battery systems are limited and have several disadvantages that will be discussed later. Space nuclear prime power systems offer certain advantages to SBR, and they have been launched into space by the United States since 1961, beginning with the SNAP-3A. 
 But such an assumption does not give grossly erroneous results, and it is justifiable when experimental human- observer data are not available or are of questionable accuracy. Curves based on actual experiments with human observers, analogous to those of Figs. 2.4 through 2.7, are given in Ref. 
 The use of wideband noise represents the earliest brute-force active jamming technique which can mask the desired target reflection. The jamming, . FIG. 
 A proposal was submitted for further work but was not  accepted.  The first application of the pulse technique to the measurement of distance was in the  basic scientific investigation by Breit and Tuve in 1925 for measuring the height of the  i~nosphere.~.'~ However, more than a decade was to elapse before the detection of aircraft by  pulse radar was demonstrated.  The first experimental radar systems operated with CW and depended for detection upon  the interference produced between the direct signal received from the transmitter and the  doppler-frequency-shifted signal reflected by a moving target. 
 The h–ΔRmaxrelationship curve. With reference to Figure 4, it can be seen that the ΔRmaxincreases with h. Applying the parameters of Table 1to Equations (17)–(19), we calculate that the height di ﬀerence threshold is 38.26 m. 
 The limiting case  is the narrowband filter bank where each individual filter consists of a small passband,  the balance being stopband. Improvement factor is an important metric, but in addition to this average metric  defined across all doppler frequencies, it is often important to characterize the perfor - mance as a function of doppler frequency, particularly with coherent doppler filtering  imbedded in the processing chain. With performance characterized versus doppler  FIGURE 3. 
 FEROMETRIC ANTENNA ON A  
 £n°{È  2!$!2 (!.$"//+  !LTIMETRY AND RADIOMETRY DATA ALSO MEASURED THE SURFACE TOPOGRAPHY AND ELECTRI 
 BEAM AMPLIFIER  PARTICULARLY ONE OF THE VARIANTS OF THE KLYSTRON  MIGHT BE THE FIRST 2& POWER SOURCE TO CONSIDER FOR A HIGH PERFORMANCE MICROWAVE RADAR THAT EMPLOYS A MECHANICALLY STEERED ANTENNA OR A CON 
 LATORS ACT ESSENTIALLY AS A TIMING STANDARD BY WHICH THE SIGNAL DELAY IS MEASURED TO EXTRACT RANGE INFORMATION  ACCURATE TO WITHIN A SMALL FRACTION OF A WAVELENGTH 4HE PROCESSING DEMANDS A HIGH DEGREE OF PHASE STABILITY THROUGHOUT THE RADAR 34!,/ )NSTABILITY  4HE FIRST LOCAL OSCILLATOR  GENERALLY REFERRED TO AS A  STABLE  LOCAL OSCILLATOR 34!,/   TYPICALLY HAS THE GREATEST EFFECT ON RECEIVER 
 ELEMENT ARRAY  WITH ELEMENT SPACING  S   K   SCANNED TO n .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°£x 4HE PATTERN MAXIMUM IS NOTED TO OCCUR AT LESS THAN  n BECAUSE THE GAIN OF THE ELEMENT  PATTERN INCREASES TOWARD BROADSIDE 4HE ELEMENT PATTERN VALUE AT  n IS COS n      IN POWER OR  IN AMPLITUDE  RELATIVE TO THE MAXIMUM AT BROADSIDE  AS EXPECTED  4HE SIDELOBES IN THE GENERAL REGION OF BROADSIDE ARE NOT REDUCED BECAUSE IN THAT REGION  THE ELEMENT PATTERN IS APPROXIMATELY UNITY 2ELATIVE TO THE BEAM MAXIMUM  THEREFORE  THE    SIDELOBES NEAR BROADSIDE ARE INCREASED BY APPROXIMATELY  D" £Î°ÎÊ *  ,Ê,,9-Ê  Ê 
 For radars that use auroral zone paths, specific analyses are required and target obscuration by spread-in-doppler clutter must be considered. The performance estimates from the figures assume that the radar design and waveforms are such that external noise is the control. The use of a single description for night and day gives a fair representation, but the transition from night to day is very abrupt and requires careful frequency management in radar operation. 
 10.8  Modulators / 10.23 10.9  Which RF Power Source to Use? / 10.25.     viii Chapter 11 Solid id-State Transmitters Michael T. Borkowski11.1 11.1  Introduction / 11.1 11.2  Advantages of Solid State / 11.1 11.3  Solid-state Devices / 11.5 11.4  Designing for the Solid-state Bottle Transmitter / 11.17 11.5  Designing for the Solid-state Phased Array Transmitter / 11.24 11.6  Solid-state System Examples / 11.37 Chapter 12 Reflector Antennas Michael E. 
 BEAM CLUTTER RESIDUE DUE TO PLATFORM MOTION EFFECTS  THE BEAM RESPONSES MUST SPAN THE RADARS MAIN 
 The general characteristics of the magnetron load will beconsidered later, and their effect onpulser behavior and design will bestudied ingreater detail forthe two main types ofpulsers. 10.7. Pulser Circuits.—To obtain substantially rectangular pulses ofshort duration and high pulse power requires that energy stored in some circuit element bereleased quickly upon demand and bereplenished from anexternal source during the interpulse interval. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°ÓÇ AS FROM THE THREE 
 vol.  MIL-6, pp. 162-169, April, 1962. 
 WATER CONCENTRATION IN CLOUDS GENERALLY RANGES FROM  TO   GM   ALTHOUGH 7EICKMANN AND +AMPE HAVE REPORTED ISOLATED INSTANCES OF CUMU 
 /Ê/,    4HE TARGET TRACKING FUNCTION OF A SHIPBORNE NAVIGATION RADAR HAS HISTORICALLY BEEN CALLED AN  !UTOMATIC 2ADAR 0LOTTING !ID !20!  4HIS TERM IS BECOMING OBSOLETE  )-/ NOW DEFINES THIS PROCESS AS  4ARGET 4RACKING 44    WHICH INCLUDES TARGET DATA  OBTAINED FROM !)3 4HE BASIC REQUIREMENT CALLS FOR A MINIMUM RADAR TRACKING CAPAC 
 59.Harvey.G.G.:ReportofConference onRapidScanning, MITRadiation Lab.Repc.54-27.June15. 1943.ASTIAAT!46616. 60.Kaiser.J.A.:SpiralAntennas Applied toScanning Arrays.Electronic Scanning Symposium, Apr. 
 IT-6, pp. 145-267, April, 1960.  I 1. 
 /,"  5NLIKE LINEAR 
 3.16) shows that if one of the modulation-  frequency harmonics is extracted (such as the first, second, or third harmonic), the amplitude  of the leakage signal at zero range may theoretically be made equal to zero. The higher the  number of the harmonic, the higher will be the order of the Bessel function and the less will be the  amount of rnicropllonism-leakage feedthrough. This results from the property that Jn(.u) be-  haves as .un for srr~all .u. 
 The National Aeronautics and Space Administration (NASA) performed successful  X/C-band single-pass polarimetric InSAR (single-pass) for the Space Shuttle Radar  Topography Mission (SRTM), using antennas on the shuttle itself and on the shuttle’s  maneuverable arm to produce a complete 3D map of the Earth’s surface between 60 °  N latitude and 56 ° S latitude—nearly 80% of the surface, with best vertical accuracy  of 6 meters on a 30-meter horizontal grid.54 Foliage-Penetration (FOPEN) SAR.  Although higher frequency (greater than  approximately 2 GHz) microwaves do not penetrate foliage well, lower frequency micro - waves do (Fleischman et al.55; see also Section 21-6 of Ulaby et al.56). For example,   for C band, the attenuation of a typical forest canopy varies from ≈ 10 dB to ≈ 40 dB;  the probability that the attenuation is less than 20 dB is about 0.2. 
 C. Currie (ed.), Norwood, MA: Artech House,1984. 103. 
 IRE, vol. 37, pp. 340–355, April 1949. 
 Trunk35 © IEEE 1984 ) ch07.indd   21 12/17/07   2:13:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 MENTAL SCATTERING CROSS SECTION FOR ELEMENT  I  BUT THIS CONCEPT IS MEANINGFUL ONLY IN AN  AVERAGE 4HUS  THE AVERAGE POWER RETURNED IS GIVEN BY  00'! ! 2RI I IN  £TI TI RIS P $   #HAPTER . £È°Ó  2!$!2 (!.$"//+  (ERE  R  HAS BEEN USED TO  DENOTE THE AVERAGE VALUE OF  RI $ !I )N THIS FORMULATION   WE MAY PASS IN THE LIMIT FROM THE FINITE SUM TO THE INTEGRAL GIVEN BY   00'! D! 2RTTR ¯   PS )LLUMINATEDAREA    4HIS INTEGRAL IS NOT REALLY CORRECT  FOR THERE IS A MINIMUM SIZE FOR REAL  INDEPENDENT  SCATTERING CENTERS .EVERTHELESS  THE CONCEPT IS WIDELY USED AND IS APPLICABLE AS LONG  AS THE ILLUMINATED AREA IS LARGE ENOUGH TO CONTAIN MANY SUCH CENTERS &IGURE  ILLUSTRATES THE GEOMETRY ASSOCIATED WITH %Q  .OTE THAT FOR A RECTAN 
 3.35. 3.16. Cities.-The brightest signals within abuilt-up area (Boston, Mass. 
 The hemispheri-  330INTRODUCTION TORADAR SYSTEMS arranged onthesurfaceofasphere,theplaneofpolarization changes with the scanangle. Withcircular polarization, however; thereisnochangewithscan. Aconventional arraywithfourfacescantrackfourtimesthenumber oftargetsasadome antenna (whichoperates withasingleplanararrayforhemispherical coverage), assuming the trafficisdistributed uniformly. 
 NOISE PLUS CHAFF RATIO IS DETERMINED ON THE BASIS OF THE CHAFF LOCATION IN THE SPACE  THE ANTENNA RECEIVING PATTERN  AND THE RADIATED RADAR WAVEFORM 4HE RADAR EQUATION CAN BE APPLIED  AND THE SIGNAL PROCESSING SCHEME CAN BE EMULATED TO DETERMINE THE AMOUNT OF CHAFF MITIGA 
 This will be particularly bad  with radars which cannot cancel second-time-around clutter, such as those with pulse-to-pulse  staggered pulse repetition frequencies or those which use magnetron transmitters with random  starting phase pulse to pulse. The accuracy of precision range measuring systems that utilize  phase measurements. as in the Tellurometer (Sec. 
 317-324, May, 1968.  34. Love, A. 
 Tlie output of t11e detector contains the beat frequency (range  frequency and the doppler velocity frequency), which is amplified to a level where it can  actuate the frequency-measuring circuits.  In Fig. 3.13, the output of the low-frequency amplifier is divided into two channels: one  feeds an average-frequency counter to determine range, the other feeds a switched frequency  counter to determine the doppler velocity (assuming f, > fd). 
 21.4  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 are high in salt content or salt water because of the high absorption of electromagnetic  energy of such materials. For comparison, the total two-way path loss from Earth to  the Moon using a 1 GHz radar would be greater than 200 dB for a range of 356,400  km and a target radar cross section in the order of 1012 m2, whereas a GPR radar often  encounters a path loss in excess of 70 dB for ranges of less than a meter . In air, the GPR signal travels at the speed of light, but is slowed down in ground  materials by their dielectric constant; hence, true range needs calibrating for each  material. 
 The auxiliaries may be individual antennas or groups of receiving elements of a phased array antenna. The amplitude and phase of the signals delivered by the N auxiliaries are con- trolled by a set of suitable weights: denote the set with the TV-dimensional vector W = (W1, W2, ..., WN). Jamming is canceled by a linear combination of the sig- nals from the auxiliaries and the main antenna. 
 The angle that each of the plane waves makes with the longitudinal direction  (Figure 13.14) is determined by the H dimension of the waveguide and simulates the  angle of scan of an infinite array  sinθλ λ= c (13.21) where q = scan angle  l = free-space wavelength  lc = cutoff wavelength of guide FIGURE 13.13  Two adjacent elements coupling to  another element in the same row ch13.indd   25 12/17/07   2:39:58 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 VERTICAL SCATTERING COEFFICIENT CAN HAVE ITS ANGULAR VARIATION PROPERLY DESCRIBED &)'52%     %XAMPLES OF THE VARIATION WITH ANGLE OF INCIDENCE  OF THE NUMBER OF INDEPENDENT SAMPLES FOR A SCATTEROMETER . £È°ÓÈ  2!$!2 (!.$"//+  'ROUND AND (ELICOPTER 3CATTEROMETERS AND 3PECTROMETERS  -ANY GROUND  SCATTERING MEASUREMENTS HAVE BEEN MADE WITH SYSTEMS MOUNTED ON BOOM TRUCKS  AND HELICOPTERS -OST OF THESE ARE &- 
 Although zoning reduces the size and weight of a lens, it is not without disadvantages.  Dielectric lenses are normally wideband; however, zoning results in a frequency-sensitive  device. Another limitation is the loss in energy and increase in sidelobe level caused by the  shadowing produced by the steps. 
 Appl. Mech. 1948 ,1, 171–199. 
 TO 
 At the other extreme from the Rayleigh region is the optical region, where the dimensiol~s  of the sphere are large compared with the wavelength (2nalA % 1). For large 2na/l, the radar  cross section approaches the optical cross section na2. In between the optical and the Rayleigh  region is the Mie, or resonance, region. 
 One of the more useful concepts of probability theory needed to analyze the detection of  signals in noise is the probability-density function. Consider the variable x as representing a  typical measured value of a random process such as a noise voltage or current. Imagine each x  to define a point on a straight line corresponding to the distance from a fixed reference point. 
 TRACK AND TRACK 
 MRWS  provides complete situational awareness (perception of the surrounding tactical envi - ronment), but does not have the maximum detection range provided by the higher duty  cycle of HRWS for thermal noise-limited targets. The MRWS waveform uses M-of-N detection processing; a typical waveform  might be 3-of-7. Each MRWS dwell is made up of N looks each with a different PRF. 
 TISTICAL CHARACTERIZATIONS ARE AVAILABLE THAT ALLOW MUCH OF THE USEFUL SEA CLUTTER REGIME TO BE DESCRIBED IN WAYS THAT CAN BE OF PRACTICAL VALUE TO THE RADAR COMMUNITY  PROVIDED THAT SOME CARE IS TAKEN IN DEFINING AND OBSERVING THE PERTINENT PARAMETERS (OWEVER  THERE ARE MAJOR AREAS OF UNCERTAINTY PRESENT AT ANY WIND SPEED  WHENEVER THE GRAZING ANGLE GOES BELOW A FEW DEGREES  AND THE SURFACE ILLUMINATION BEG INS TO FEEL THE EFFECTS  OF REFRACTION AND DIFFRACTION  AND AT  ANY GRAZING ANGLE  WHENEVER THE WIND SPEED IS  LESS THAN ABOUT  KT  WHERE PECULIARITIES AND UNCERTAINTIES IN THE GENERATION OF SURFACE ROUGHNESS BEGIN TO EMERGE MOST STRONGLY !T THE LOW GRAZING ANGLES ENCOUNTERED IN MARITIME RADAR OPERATIONS  SEA CLUTTER BECOMES SPIKY AND INTERMITTENT  REQUIRING SPE 
 MENTS A PHASE SHIFT  WHERE EACH STAGE REPRESENTS AN ITERATION IN THE FLOW CHART !N  . 
  n E E n n n n E 
 TERN IS SHOWN AT A TIME SEVERAL PULSE DURATIONS AFTER APPLICATION 4HE OUTER PERIMETER  REPRESENTS THE ENERGY RADIATED AT TIME ZERO FOLLOWED AT INTERVA LS BY THE RADIATION FROM  THE FEED POINTS AND THE END OF THE ELEMENT !S IT IS REQUIRED TO RADIATE ONLY A VERY SHORT IMPULSE  IT IS IMPORTANT TO ELIMINATE  THE REFLECTION DISCONTINUITIES FROM THE FEED POINTS AND ENDS OF THE ANTENNA EITHER BY END LOADING OR BY REDUCING THE AMPLITUDE OF THE CHARGE AND CURRENT REACHING THE ENDS 4HE LATTER CAN BE ACHIEVED EITHER BY RESISTIVELY COATING THE ANTENNA OR BY CONSTRUCTING THE ANTENNA FROM A  MATERIAL SUCH AS .ICHROME   WHICH HAS A DEFINED LOSS PER UNIT AREA  )N THIS CASE  THE ANTENNA RADIATES IN A COMPLETELY DIFFERENT WAY AS THE APPLIED CHARGE BECOMES SPREAD OVER THE ENTIRE ELEMENT LENGTH  AND HENCE  THE CENTERS OF RADIATION ARE DISTRIBUTED ALONG THE LENGTH OF THE ANTENNA 4YPICAL RADIATED F IELD PATTERNS FOR A RESIS 
 NITRIDE 
 TIVELY LOW  HELPING TO MAKE THE CLUTTER REJECTION OF THE DIFFERENTIATOR ADEQUATE FOR ITS PURPOSE 3UCH CLUTTER VARIES APPROXIMATELY WITH THE FOURTH POWE R OF FREQUENCY  AND  SO A  '(Z SYSTEM INHERENTLY EXPERIENCES  D" LESS CLUTTER THAN A  '(Z SYSTEM  ASSUMING IDENTICALLY SIZED CLUTTER CELLS &OR THIS REASON  ON SHIPS FITTED WITH BOTH  AND  '(Z RADARS  THE  '(Z RADAR IS OFTEN PREFERABLE  EXCEPT WHEN MANEUVERING IN CLOSE SITUATIONS  FOR EXAMPLE  IN HARBORS WHEN THE NORMALLY SUPERIOR AZIMUTH RESOLUTION OF A  '(Z RADAR IS PREFERRED 3EA #LUTTER 4HE REDUCTION OF SEA CLUTTER TO LEVELS ACCEPTABLE TO THE USER IS A  FAR MORE DIFFICULT PROBLEM  AND AS YET  COMMERCIAL RADARS DO NOT MEET ALL THE IDEAL DEMANDS OF USERS 3MALL CRAFT AND BUOYS CAN EASILY BE OBSCURED IN SEA CLUTTER )N THE DAYS BEFORE PRECISE  'LOBAL .AVIGATION 3ATELLITE 3YSTEMS  '.33   SUCH AS '03   THE SAFE NAVIGATION OF A SHIP IN COASTAL WATERS IN POOR VISIBILITY WAS DOMINATED  BY THE RADAR BEING ABLE TO DISCERN NAVIGATION MARKERS  SUCH AS BUOYS 0ASSIVE MARKERS   INCLUDING THOSE SUPPLEMENTED BY RADAR REFLECTORS  CAN BE NOTORIOUSLY DIFFICULT TO DETECT IN HIGHER SEA 
 19.1 include the peak transmit  power Pt, the antenna system gain G twice (once for transmitting and once for receiv - ing), and the wavelength l. We include all antenna system losses in this antenna sys - tem gain factor (radome, waveguide, rotary joints, etc.) since all the measurements  must be referenced to the same point in the radar system—usually at a coupler near  the circulator. Because the antenna gain is not uniform over the beamwidth, assuming  a uniform gain can lead to errors in the calculation of Z. 
 1976. 30.Croncy. J.:ClullcrandItsReduction onShipborne Radars. 
 Part 1: formulation and simulation,” J. Atmos. Oceanic Technol ., vol. 
 ”Often these 1W.L.Myers, USN”R, “Weight Analysis ofAirborne Radar Sets,” RLReport No.450, Jan, 1,1945. 2Chap. 11contains adiscussion ofthetransmission lineandassociated components.. 
 The curves in Figure 2.23 and Figure 2.24,  which have been referred to several times, give the approximate limitation on I caused  by pulse-to-pulse staggering and either antenna scanning or internal clutter motion.  They have been derived as explained below. A two-delay canceler will perfectly cancel a linear waveform, V(t) = c + at, if  it is sampled at equal time intervals independent of the constant c or the slope a. 
 10.9 Shift-register generator.MOD 2ADDER OUTPUT . TABLE 10.5 Maximal-Length Sequences equal to the number of subpulses in the sequence and is also equal to the time- bandwidth product of the radar system. Large time-bandwidth products can be obtained from registers having a small number of stages. 
 ONLY  SHAPED 
 When half-wavelength-spaced slots are fed in a  series fashion, the field inside the guide changes phase by 180" between elements. The phases of  every other slot therefore must be reversed to cause the radiated energy to be in phase. This is  accomplished in a slotted waveguide by altering the direction of tilts of adjacent elements. 
 PUT .OTE )N -4)  A SINGLE VALUE OF  #! WILL BE OBTAINED  WHILE IN DOPPLER RADAR THE VALUE  WILL GENERALLY VARY OVER THE DIFFERENT TARGET DOPPLER FILTERS )N -4)   #! WILL BE EQUAL TO -4)  IMPROVEMENT FACTOR IF THE TARGETS ARE ASSUMED UNIFORMLY DISTRIBUTED IN VELOCITY  3EE ALSO  -4)  IMPROVEMENT FACTOR (ERE  IT WILL BE ASSUMED THAT hPROCESSORv REFERS TO THE -4) FILTER OR A SINGLE DOPPLER  FILTER IN A PULSE DOPPLER FILTER BANK "ASED ON THIS DEFINITION  THE CLUTTER ATTENUATION IS  GIVEN BY   #!0 00 0 #). #/54./54 .).    WHERE 0#). AND 0#/54 ARE THE CLUTTER POWER AT THE INPUT AND OUTPUT OF THE -4) FILTER   RESPECTIVELY  AND  0.). AND 0./54 ARE THE CORRESPONDING NOISE POWERS !S NOTED IN THE  )%%% DEFINITION  THE VALUE OF #! WILL MOST LIKELY DIFFER FROM FILTER TO FILTER IN A DOPPLER  FILTER BANK DUE TO SPECIFIC CLUTTER AND FILTER RESPONSE CHARACTERISTICS )N THE DISCUSSION ABOVE  THE ASSUMPTION WAS IMPLICITLY MADE THAT CLUTTER RETURNS ARE  STATIONARY AND DISTRIBUTED IN RANGE 4HE ABOVE DEFINITIONS WILL  BE EQUALLY VALID BEFORE  AND AFTER PULSE COMPRESSION &OR A SINGLE PIECE OF POINT CLUTTER  AS OFTEN USED IN ACTUAL RADAR STABILITY MEASUREMENTS  THE DEFINITION OF CLUTTER ATTENUATION WOULD HAVE TO BE CHANGED AS FOLLOWS TO PROVIDE IDENTICAL RESULTS CLUTTER ATTENUATION #!   POINT CLUTTER  )N MOVING 
 "AND !IR 4RAFFIC #ONTROL 4RANSMITTER   4HE 2ADAR -ODERNIZATION  0ROJECT 2!-0  RADAR SYSTEM IS AN , BAND SYSTEM BUILT BY THE 2AYTHEON #OMPANY DUR 
              
 LEVEL 2& ADAPTED    .   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°x 4HE APERTURES ARE SIGNAL CONDITIONED  CONTROLLED  AND INTERFACED THROUGH BUSSES IN THE  AIRCRAFT WITH REMAINING PROCESSING PERFORMED EITHER IN A COMMON PROCESSOR COMPLEX   AS SHOWN IN &IGURE   OR IN FEDERATED PROCESSORS DISTRIBUTED THROUGHOUT THE AIRCRAFT /NE IMPORTANT CLASS OF STANDARDIZED MODULES CONTAINS BASIC TIMING AND PROGRAMMABLE EVENT GENERATORS 0%'  THAT CREATE ACCURATE TIMING FOR 0ULSE 2EPETITION &REQUENCIES 02&S   ANALOG TO DIGITAL CONVERSION !$  SAMPLING  PULSE AND  CHIP WIDTHS  BLANK 
 WIDTH   WHICH  IN TURN  REDUCES CHAFF RETURNS AND RESOLVES TARGETS TO A HIGHER DEGREE 3OME ADVANTAGE CAN BE GAINED BY INCLUDING THE CAPABILITY TO EXAMINE THE JAMMER  SIGNALS  FIND HOLES IN THEIR TRANSMITTED SPECTRA  AND SELECT THE RADAR FREQUENCY WITH THE LOWEST LEVEL OF JAMMING 4HIS APPROACH IS PARTICULARLY USEFUL AGAINST PULSED %#-  SPOT NOISE  AND NONUNIFORM BARRAGE NOISE ITS EFFECTIVENESS DEPENDS PRIMARILY ON THE EXTENT OF THE RADAR AGILE BANDWIDTH AND THE ACQUISITION SPEED AND FREQUENCY TRACKING OF AN hINTELLIGENTv JAMMER ! TECHNIQUE SUITED TO THIS PURPOSE IS REFERRED TO AS  AUTOMATIC  FREQUENCY SELECTION !&3    !NOTHER METHOD TO REDUCE THE EFFECT OF MAIN 
 f(t)-f(t+T)-f(t+T)+f(t+2T) Thisconfiguration iscommonly calledthethree-pulse canceler. Transversal'tnters. Thethree-pulse canceler showninFig.4.9bisanexample ofatransversal filter.ItsgeneralformwithNpulsesandN - 1delaylinesisshowninFig.4.11.Itisalso sometimes knownasafeedforward filter,anonrecursive filter,afinitememoryfilteroratapped delay-line filter.Theweights WIforathree-pulse cancelerutilizingtwodelaylinesarranged asa transversal filterare1,-2,1.The/requency response function isproportional tosin2nhT. 
 GROUND LEVEL FOR EACH RANGE 
 on K;~tl;~r. 1)isplays. IVir.c~lt.s.s 111qr.. 
 SQUAREDDISTRIBUTIONWITHDEGRES SSOFFREEDOM  FOR3WERLING))TARGETCHI 
 426 INTRODUCTION TO RADAR SYSTEMS  small size, and highly reproducible in manufacture. The amplitude weighting to reduce  sidelobes can be integrated directly into the interdigital transducer design. In addition to the  linear FM, they can be designed to operate with nonlinear frequency modulations, phase-coded  pulses, and the burst pulse. 
 NOISE RATIO AT THE RECEIVER IS HELD CONSTANT AT ALL POSITIONS ALONG THE RECEIVE BEAM 4HIS SCHEME IS ANALOGOUS TO THE MONOSTATIC AIR SURVEILLANCE RADAR USING A COSECANT 
 NAL 4HE OUTPUT FROM MOST ULTRAWIDEBAND RADAR SYSTEMS CAN BE COMPARED IN TERMS OF A TIME 
          
 (11.1) is canceled by an identical but implicit R2 term in the denominator. Consequently the dependence of the RCS on /?, and the need to form the limit, usually disappears. Radar cross section is therefore a comparison of the scattered power density at the receiver with the incident power density at the target. 
 ,/" - 3EARCH RADARS GENERALLY REQUIRE  n AZIMUTHAL COVERAGE 4HIS COVERAGE IS DIFFICULT  TO OBTAIN ON AN AIRCRAFT SINCE MOUNTING AN ANTENNA IN THE CLEAR PRESENTS MAJOR DRAG  STABILITY  AND STRUCTURAL PROBLEMS 7HEN EXTENSIVE VERTICAL COVERAGE IS REQUIRED  THE AIRCRAFTS PLANFORM AND VERTICAL STABILIZER DISTORT AND SHADOW THE ANTENNA PATTERN !NALYSIS OF TACTICAL REQUIREMENTS MAY SHOW THAT ONLY A LIMITED COVERAGE SECTOR IS REQUIRED (OWEVER  THIS SECTOR USUALLY HAS TO BE CAPABLE OF BEING POSITIONED OVER THE FULL n RELATIVE TO THE AIRCRAFTS HEADING BECAUSE OF THE REQUIREMENTS FOR COVERAGE &)'52%   % 
 309-313, May, 1973.  22. Graham, R.: The Polarisation Characteristics of Offset Cassegrain Aerials, "Radar - Present and  Future," Oct. 
 It suppresses ever) tiarrnonics of both the RF and the LO   signal^.^.^^  Reactive image termination. If the image frequency of a mixer is presented with the proper  reactive termination (such as an open or a short circuit), the conversion loss and the noise  figure can be 1 to 2 dB less than with a "broadband" mixer in which the image frequency is  terminated in a matched The reactive termination causes energy converted to the  image frequency to be reflected back into the mixer and reconverted to IF.'6-24  Both the sun1 and the image frequencies can be reflected back to the diode mixer to  achieve a lower conversion loss, but a number of adjustments are required for good results.24  One method for terminating the image in a reactive load is to employ a narrow bandpass filter,  or preselector, at the RF signal frequency. A limitation of this approach is that it is not suitable  for very wide bandwidths. 
 2. Moding: If other possible operating-mode conditions exist too close to the normal-mode current level, stable operation is difficult to achieve. Start- ing in the proper mode requires the proper rate of rise of magnetron cathode voltage, within limits that depend on the tube starting time and the closeness of other modes. 
 This method can beapplied toany type ofindex ormarker, and has obvious uses asasubstitute forelaborate computing circuits under some circumstances. 7.4. The Relay ofRadar Displays.—It iscommon forthebest location ofthe radar station and the optimum location ofacontrol center tobe different. 
 Statistical independence between sequential returns observed by  a radar altimeter depends primarily on the radar pulse repetition rate, the antenna size,  the spacecraft velocity, and on the sea surface conditions.67 The antenna was a 1.5-m  reflector that served both altimeter bands and also the radiometer. Selected param - eters associated with the altimeter’s design are listed in Table 18.5. The pulse-to-pulse   ‡  Total mass, not including consumables such as fuel for propulsion or attitude control.TABLE 18.5  TOPEX Parameters Parameter Value Units LFM rate 3.125 MHz/µs Pulse duration 102.4 µs Pulse BW (radiated) 320 MHz Time × bandwidth 32768 (dimensionless) Pulse resolution 0.469 m Carrier (Ku band) 13.6 GHz Carrier (C band) 5.2 GHz IF frequency 500 MHz Stretch bandwidth 3 MHz Range time span 400 ns ch18.indd   35 12/19/07   5:14:53 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 It was not possible to install the scanner on the aircraft hull and so two scanners were used, one on each wing at equal distances from the hull. The two scanners were synchronised to a maindrive. RF energy was switched between scanners so that they each transmitted and received over a 180 °sector to the sides of the aircraft. 
 CLUTTER VIS 
 SMOOTH SURFACE  PRESUMABLY PRODUCED BY POWERFUL SURFACE 
 TIME CHARACTERISTICS  BISTATIC 34!0 METHODS ARE NOT SIMPLE APPLICATIONS OF MONOSTATIC APPROACHES  BUT A NEW CLASS OF ALGORITHMS 3PECIFICALLY  THEY APPLY A DATA 
 AP-28, pp. 538–545, 1980. 119. 
 7.12  can reduce aperture blocking. The subreflector consists of a horizontal grating of wires, called  a trart~r~jlector, which passes vertically polarized waves with negligible attenuation but reflects  the horizontally polarized wave radiated by the feed. The horizontally polarized wave reflected  by the subreflector is rotated 90" by the twist rejector at the surface of the main reflector. 
 Rawson, and F. L.  Smith, “Bistatic clutter measurements,” IEEE Trans. 
    
 Sincethefrequency response function ofadelaylineoftimedelayTisexp(-j2nfT),1l(f)forthesingle-delay-line canceler is H(f)=I -exp(-j2nfT)=2jsin(nfT)exp(-jnfT) (4.22) Substituting Eqs.(4.19)and(4.22)intoEq.(4.21)andassuming that(Jc~liT,theclutter attentuation is f~Woexp(-f2/2(J;)dfCA=-;;w-:;: ..~_":'----=--'''-:---~-'----~:-=--,---foWoexp(-f2j2(J;)4sin2nfTdf 0.5(4.23). If tlie exponent in the denorniriator of Eq. (4.23) is small, tlie exponential term can be replaced  by the first two terms of a series expansion, or  where ,f,, the pulse repetition frequency, has been substituted for 1/T. 
 The exact location ofaplace onthe ground may beofimportance toaradar- equipped aircraft even though there isnodistinguishable radar target atthat point. Innearly allcases where itwould beadvantageous ifan echo could bemade much stronger ormore readily distinguishable from other confusing ones, theuseofaradar beacon isindicated. (An enemy aircraft obviously constitutes one difficult exception. 
 Thus ifwehave afrequency band f which istobesplit into npieces, thetime required forsuch adevice asa Frahm meter torespond isofthe order n/f, whereas ifthe nfrequency intervals areobserved insequence thetime isn2/f. The general design procedure isessentially thesame asthat described inSec. 5.8. 
 W. Crispin, and K. M. 
 3, pp. 85-92, January 1968. 32. 
 This is the essence of the  stability problem. The magnetron must be designed with but one mode dominant. The rr mode  is usually preferred since it can be more readily separated from the others. 
 CYCLE SILICON BIPOLAR POWER TRANSISTOR IN A CUSTOM HERMETIC   DUAL 
 The same factor has tobeapplied again incomputing the return signal totake account oftheinterference along thereturn path: The assumption ofa flat earth isagood approximation’ uptoranges somewhat greater than 4h,hzR,=~. The cross section isthus redefined bytheequation s=g.4:R2 –“”14‘in2(2+a12”An attempt has been made inRL Report No. 401 toextend the validity ofthis definition toinclude ship targets bydetermining experi- mentally an“effective value” forR,.This isdone byobserving the range atwhich theattenuation ofthereturn signal becomes greater than that predicted bythe inverse fourth-power law. 
 Volume Search. Assume that the radar must search an angular volume of H steradians in the time ts. If the antenna beam subtends an angle of £lb steradians, the antenna gain G, is approximately 4Tcl£lb. 
 SHUTTLE RADAR FOR  SYNTHETIC APERTURE RADAR 3!2  GROUND MAPPING THE 4")2$ PROGRAM OPERATING WITH  *OINT 34!23 FOR SILENT AIR 
 61,  pp. 299-330, March, 1973.  8. 
 PLUS 
  AND  TWO 
 When the PRF is high, so that many range ambiguities occur, the target range delay  may be considered to be random from frame to frame, with a uniform distribution over  the IPP. A measure of performance reduction due to eclipsing and range gate straddle  is found by 1. Using the uneclipsed detection curve ( Pd vs. 
 This rate, qR, was initially identified by Jackson21 and subsequently verified by  Moyer and Morgan119:  q bR R c R=tan( )/ /2  (23.18) For operation in the co-site region (see Table 23.2),qRcan vary from 1 °/µs near the  baseline to 0.01 °/µs when RT + RR > L. Typical qRcontours are shown in Jackson.21  These rates and rate changes require an inertialess antenna, for example, a phased  array with diode phase shifters. Normally, a phased array antenna used for surveillance  is programmed to switch beams in increments of a beamwidth. 
 HOUR POLAR ORBITS WITH A PERIAPSIS  ^ KM    AT n. LATITUDE  AND APOAPSIS ^   KM -AGELLAN MAPPED OVER  OF THE SURFACE OF 6ENUS &IGURE   WITH IMAG 
 Burgess, D., et al.: Final Report on the Joint Doppler Operational Project (JDOP), 1976-1978, NOAA Tech. Memo. ERL NSSL-S6, 1979. 
 Whenthisoccurs,thereisanincrease intheradarbackscatter sincewaterparticles reflect morestrongly thanice.Astheice',partides, snow,orhailbegintomelt,theyfirstbecome water-coated icespheroids. Atradarwavelengths, scattering andattenuation bywater-coated icespheroids thesizeofwetsnowflakes issimilarinmagnitude tothatofspheroidal water dropsofthesamesizeandshape.Evenforcomparatively thincoatings ofwater,thecomposite particlescatters nearlyaswellasasimilarall-water particle. Radarobservations oflightprecipitation showahorizontal" brightband"atanaltiiude atwhichthetemperature isjustaboveO°c.Themeasured reflectivity inthecenterofthebright bandistypically about12to15dBgreater.thanthereflectivity fromthesnowaboveitand about6to10dBgreaterthantherain'below.70Thecenterofthebrightbandisgenerally from about100to400mbelowtheO°C:isotherm. 
 128. I. S. 
 #7 WAVEFORM  SO WIDELY SEPARATED SITES ARE NEEDED TO MINIMIZE THE LEAKAGE OF THE TRANSMITTER INTO THE RECEIVER -ICROWAVE RADARS HAVE USED &- 
 The conventional CRT usually requires a darkened room or the use of a viewing  hood by the operator. In spite of the limitations of the conventional CRT display, it is almost  universally used for radar applications. Many of its limitations can be overcome, but  sometimes with a sacrifice in some other property. 
 It is a good frequency for lower- cost radars and for long-range radars such as those for the detection of satellites. It is also the frequency region where it is theoretically difficult to reduce the radar cross section of most types of airborne targets. In spite of its many attractive features, there have not been many applications of radar in this frequency range because its limitations do not always counterbal- ance its advantages. 
 There isnow good evidence that ascan rate of6rpm isdesirable for complex tracking and control, and even higher rates should beadvanta-c geous. Mechanical difficulties athigh scan rates and requirements for high azimuth accuracy will probably conspire tosetanupper limit on future scanning rates. Infact rates above 6rpm may beentirely ruled out bythese limitations. 
 New York, 1950.  9. SchelkunofT. 
 Guest editorial and invited papers in special issue on high-frequency and ice mapping and ship  location, IEEE J. Oceanic Eng ., vol. OE-11, April 1986. 
 IRE, vol. 49, pp. 1184-1192, July 1961. 
 High accuracy time and frequency synchronization, including  range opening and doppler effects between both ends of the link can dramatically  reduce the effectiveness of jamming by narrowing the susceptibility window. Time  and frequency synchronization also minimizes acquisition or reacquisition time. ch05.indd   26 12/17/07   1:27:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 ING DESCRIPTIONS OF THE SEA SURFACE )T WOULD SEEM A SIMPLE MATTER TO REFINE THESE RESULTS BY USING INSTRUMENTATION  RADARS OPERATING OVER THE WIDE VARIETY OF RADAR AND ENVIRONMENTAL PARAMETERS ENCOUN 
 There are several techniques generally used to handle this increased dynamic range  in fixed-point FFTs. One scheme would be to ensure that the computation stages carry  enough bits to accommodate the bit-growth. For example, in our 8-point FFT example,  if we assume that the input samples are 12-bit complex numbers, and if we assume  that the magnitudes of the complex numbers do not exceed 12 bits, then the final FFT  outputs could grow 3 bits compared to the inputs, so the FFT computations could be  performed with 15 bit or larger adders. 
 By determining the spectrum of the return, the user can establish the  scattering from different ranges. This system has been used in determining the sources  of scatter in vegetation43–45 and snow. Ultrasonic waves in water can be used to simulate electromagnetic waves in air.99–101  Because of the difference in velocity of propagation, an acoustic frequency of 1 MHz  corresponds with a wavelength of 1.5 mm. 
 TION TIMES NEEDED FOR EFFECTIVE DOPPLER PROCESSING 4HE IONOSPHERE HAS A DOMINATING INFLUENCE ON SKYWAVE RADAR  WHEREAS THE NORMAL ATMOSPHERE HAS VERY LITTLE EFFECT ON MICROWAVE RADAR 4HE SKYWAVE RADARS FREQUENCY AND OTHER PARAMETERS ARE DRIVEN PRIMARILY BY THE NEED TO PROPAGATE VIA THE IONOSPHERE #ONSTRAINTS IMPOSED BY PROPA 
 Image Processing Steps In this section, we describe the image processing approach for extracting change maps. The inputs are two registered SAR images of the same ﬁeld of view that were taken at different times, i.e., “reference” image and “mission” image. Due to the large size of the images, images were divided into subimages for processing. 
 68. Crispin, J. W .. 
 Intermodulation distortion is a nonlinear pro - cess that results in generation of frequencies that are linear combinations of the fun - damental frequencies of the input signals. Second and third order intermodulation are  the most commonly specified, and the performance of the receiver is usually specified  in terms of two-tone second and third order input intercept points. The intercept point  is the extrapolated level at which the power in the intermodulation product equals that  of the two fundamental signals. 
 Insects can be carried by the wind; therefore angels due to insects  might be expected to have the velocity of the wind. Insect echoes are more likely to be found at  the lower altitudes, near dawn and twilight. The majority of insects are incapable of flight at  temperatures below 40°F (4.5"C) or above 90°F (32°C): consequently, large concentrations of  insect angel echoes would not be expected outside this temperattrre range. 
   NO   *ULY   # 7ILEY  h3YNTHETIC APERTURE RADARS v  )%%% 4RANSACTIONS !EROSPACE AND %LECTRONIC 3YSTEMS    VOL !%3 
 This  is an entirely different form of the radar equation than when the target detection is dominated  by receiver noise alone. The range in Eq. (13.8) appears as the first power rather than as the  fourth power in the usual radar equation of Eq. 
 With a pulse or other range-measuring system, reported values are always in error  because, as indicated above, it is almost impossible to resolve a narrow range of angles  near the vertical. For short ranges, one can configure the antenna so that a plane wave  impinges on the surface. When this is done, the near-vertical scattering coefficient can  have its angular variation properly described.93FIGURE   16. 
 If aradarhasapulselengthof1-microsecondduration,thetargetswouldhavetobe separated by more than 164 yards before they would appear as two pipson the PPI. Radio-frequencyenergytravelsthroughspaceattherateofapproximately 328yardspermicrosecond.Thus,theendofa1-microsecondpulsetravelingthrough the air is 328 yards behind the leading edge, or start, of the pulse. Ifa 1-microsecond pulse is sent toward two objects on the same bearing,separated by 164 yards, the leading edge of the echo from the distant targetcoincides in space with the trailing edge of the echo from the near target. 
 B.Tech ( ECE)  R-18      Malla Reddy College of Engineering and Technology (MRCET)  MALLA REDDY COLLEGE OF ENGINEERING AND TECHNOLOGY   IV Year B.Tech. ECE -I Sem       L T/P/D  C  3  -/ - /- 3  CORE ELECTIVE – V  (R18A0419) RADAR SYSTEMS   COURSE OBJECTIVES   1. To learn Radar Fundamentals like Radar Equation, Operating frequencies &  Applications. 
 LINE) Lr, TrACTIVETRANSDUCER(RECEIVER) T6,GOUTPUTB A . The antenna noise temperature is not dependent on the antenna gain and beam width when a uniform-temperature source fills the beam. If the noise sources within the beam are of different temperatures, the resulting antenna tem- perature will be a solid-angle-weighted average of the source temperatures. 
 Materials such as carbon-fiber composites, which are sometimes used in aero-  space applications, can further reduce the radar cross section of targets as compared with that  produced by liiglily reflecting metallic materials.62  50 0 04 08 1.2 1.6 2.0 2.4  Diameter in wavelengths Figure 2.13  a set of 40" Radar cross section of  cones, double-backed  1 cones, cone-spheres, double-  rounded cones, and circular ogives  as a function of diameter in wave-  lengths. (From ~Iore,~' lEEE  Trans.)  THERADAR EQUATION 37 wave"whichtravelsaroundthehaseofthesphere.Thenose-on radarcrosssectionissmall anddecreases astilesquareofthewavelength. Thecrosssectionissmalloverarelatively large angular region.Alargespecular returnisobtained whenthecone-sphere isviewedatnear perpendicular incidence totheconesurface,i.e.,when(}=90-a,wherea=conehalfangle. 
 The radar signal issometimes used toin- tensify thespot inorder todistinguish ~irnuth between perfect pointing and notar-error FIG.6.13.—Spot. errorindicator with get. Range canbeindicated bycaus- wings toindicate tmget range. 
 E77–B, no. 10, pp. 1264–1271, October 1994. 
 The supersonic delay line was used asadelay device inthe MTI systems that have had themost thorough testing; itsuseistherefore assumed inwhat follows. Certain advantages attend the use ofa storage tube, notably the ability toapply MTI toasystem whose. 632 MOVING TARGET INDICATION [SEC. 
 The area within the yellow rectangle was still under construction until December 2015. The phase model of Equation (8) was established for each high coherence point, and the unknown parameters ( v,E,η,andΔZ)were obtained by the methods discussed in Section 2.4. Based on the investigation of geological data and rock structure characteristics in the test area, the initial individual gene range was set as follows: the elastic modulus coe ﬃcient Ewas set within the range of [0, 50] MPa, the viscosity ηwithin the range of [0, 8]×106Mpa·s, the linear velocity vwas in the interval [−0.5, 0.2 ]m, and the elevation correction ΔZwas in the interval [−50, 50 ]m. 
 This phenomenon has  been experimentally verified for ship targets at short ranges where the plane-earth approxima-  tion has some validity.' Another difference between Eq. (12.8) and the normal radar equation  is the factor CIA, which appears in place of the factor Gl.  The analysis in this section is based on many simplifying assumptions; therefore care  should be exercised in adapting the results and conclusions to more realistic situations. 
 NORMAL INCIDENCE ANGLES  /THER SPECIALIZED MODELS HAVE  BEEN USED FOR PARTICULAR PURPOSES ,ATER THEORETICAL WORK FOR SURFACES INVOLVES SOLVING INTEGRAL EQUATIONS FOR THE SCAT 
 Although thisisasimplemethod ofelectronic steenng, itdoes notusuallyallowthefrequency bandtobeusedforotherpurposes, suchasforhighrange­ resolution orforfrequencyagility.\· IftooshortapulseQoowideasignalbandwidth)·is usedinthefrequency-scan array,the patternwillbedistorted. Therearetwoequivalent methods forviewing thislimitation. From thefrequency domain pointofview,eachspectral component offrequency corresponds toa different pointing direction. 
 MER TO HAVE TO SPREAD ITS POWER OVER A WIDE FREQUENCY RANGE AND WILL  THEREFORE  REDUCE THE HOSTILE JAMMING SIGNAL STRENGTH OVER THE BANDWIDTH OF THE RADAR SIGNAL &REQUENCY DIVERSITY OVER A WIDE BAND ALSO MAKES IT MORE DIFFICULT BUT NOT IMPOSSIBLE  FOR A HOSTILE INTERCEPT RECEIVER OR AN ANTIRADIATION MISSILE TO DETECT AND LOCATE A RADAR SIGNAL 4HE $OPPLER 3HIFT IN 2ADAR  4HE IMPORTANCE OF THE DOPPLER FREQUENCY SHIFT  BEGAN TO BE APPRECIATED FOR PULSE RADAR SHORTLY AFTER 7ORLD 7AR )) AND BECAME AN INCREASINGLY IMPORTANT FACTOR IN MANY RADAR APPLICATIONS -ODERN RADAR WOULD BE MUCH LESS INTERESTING OR USEFUL IF THE DOPPLER EFFECT DIDNT EXIST 4HE DOPPLER FREQUENCY SHIFT F D CAN BE WRITTEN AS   FV VDR   C O S   LQ L    WHERE VR   V COS P  IS THE RELATIVE VELOCITY OF THE TARGET RELATIVE TO THE RADAR  IN MS   V IS   THE ABSOLUTE VELOCITY OF THE TARGET IN MS   K IS THE RADAR WAVELENGTH IN M  AND  P IS THE  ANGLE BETWEEN THE TARGETS DIRECTION AND THE RADAR BEAM 4O AN ACCURACY OF ABOUT  PER 
 6 of" Radar Handbook," ed. by M. I. 
 The frequency response of a single-delay-line canceler (Fig. 4.7) does not  always have as broad a clutter-rejection null as might be desired in the vicinity of d-c. The  clutter-rejection notches may be widened by passing the output of the delay-line canceler  through a second delay-line canceler as shown in Fig. 
 d (km) = 130 ,/-) (12.1 1d)  Figure 12.6 (a) Bending of antenna beam due to refraction by the earth's atmosphere; (h) shape of beam in  equivalent-earth representation with radius &a.  (12.10)PROPAGATION OFRADAR WAVES449 increases withaltitude, causingradiowavestobenddownward. Theresultisanincrease inthe effective radarrangeaswasillustrated inFig.12.5a.(Variations oftherefractive indexinthe horizontal planemayalsoexist,buttheydonotmaterially alterthebending.) Refraction ofradarwavesintheatmosphere isanalogous tobendingoflightraysbyan opticalprism.Thepathoftheradarwavesthrough theatmosphere maybeplottedusing ray-tracing techniques, provided thevariation ofrefractive indexisknown. 
 M WAVELENGTH THE RESULT MAY BE A TRANSITION FROM ROUGH 
 Helgostam, L., and B. Ronnerstam: Ground Clutter Calculation for Airborne Doppler Radar, IEEE Trans., vol. MIL-9, pp. 
 THE 
 (FromG.W.Deley,12Courtesy McGraw-Hili BookCompany.) ambiguity diagram, maybeusedtoassessqualitatively howweIJawaveform canachievethese requirements. Eachofthesewillbediscussed briefly. Ifthereceiverisdesigned asamatched filterfortheparticular transmitted waveform, the probability 6rdetection isindependent oftheshapeofthewaveform anddepends onlyupon E/No,theratioorthetotalenergyEcontained inthesignaltothenoisepowerperunit bandwidth. 
 ( b) Pattern for a thinned array. SA is the average sidelobe level. ( after   R. 
 FULL ILLUMINATION OF THE TWO SOLAR PANEL ARRAYS IN ALL SUN 
 2.41  Divergence Factor  .............................................  2.42 Spherical-Earth Pattern Pr opagation Factor   .......  2.42  The Intermediate Region  ................................... 
    THAT WAS USED IN THE EXPERIMENTAL 7 
 RATE )& SAMPLING v IN  0ROC OF THE  3YMPOSIUM ON 7IRELESS  0ERSONAL #OMMUNICATION  "LACKSBURG  6!  *UNE &)'52%   $IRECT 
 A. G. Blyakhman et al., “Forward scattering radar moving object coordinate measurement,”  IEEE International Radar Conference , 2000. 
 It:t:t:1975 IlItemat;ollal Radal'CO/!IL-rellce. Apr.21-23.1975. Arlington. 
 The r-fline between theshock-mounted transmitter-receiver and therigidly attached scanner hasapressure-tight flexible section. Where possible, asinthecase ofthe transmitter-receiver, center-of-gravity shock mounts areused. Tominimize theeffect ofvariations insupply voltage and waveform, full-wave rectifier power supplies with choke-input filters are used throughout the set. 
 Once a target beginning is realized, the detector must be able to sense tye end of the  region of increased-density of ls. Again, if it is too sensitive to change, the detector will tend to  split targets. 1 •  ,I  Tapped-delay-line integrator. 
 These blips can be separated by  any prearranged time-intervals, such as siz second,  which correspond to increments of range equal to  ro miles. If we set the Cal up like this and switch it on  a series of bright lines appears along our main time-base  line on the CRT, giving a sort of fence or tooth-comb  effect. We should not forget that although this tooth-  comb appears to be stationary, it is really only the  electron beam being moved out of its track several times  on each trace, at precise intervals of time. 
 TIME FUNCTION FOR A TANGENT 
 For large facets (compared with wave - length), most of the return occurs almost at normal incidence, whereas for small facets  the orientation may be off normal by a considerable amount without great reduction  in scatter. As the wavelength is increased, the category of a given facet changes from  large  to small;  eventually the facet is smaller than a wavelength, and its reradiation  pattern shape remains almost isotropic from that point. Many facets that would be  separate at, say, a 1-cm wavelength are combined at a 1-m wavelength; the result may  be a transition from rough- to smooth-surface behavior. 
 Iwata, M. Kanamori, and  M. Kuzuhara, “100W L-band GaAs power FP-HFET operated at 30V ,” in IEEE Microwave  Theory and Techniques Symposium Digest , 2000, pp. 
 Four parameters determine the operation of the  magnetron. These are (1) the magnetic field, (2) the anode current, (3) load conductance, and  Figure 6.5 Photograph of the SFD-319 K,-  band fixed frequency inverted coaxial magnet-  ron. This tube delivers a peak power of 100 k W  with a 0.005 duty cycle at a frequency between  34,512 and 35.208 GHz. 
 RESOLUTION INFOR 
 The clutter-to-noise ratio from each radar resolution cell is the integral of Eq. 4.2  over the doppler and range extent of each of the ambiguous cell positions on the  ground.27–31 Under certain simplified conditions, the integration can be closed-form,32  but in general, numeric integration is required. Main-beam Clutter. 
 1525-1538, Feb. 20, 1971.  3. 
  *ASON 
 with the slightly greater loss heing a price to pay for the  convenience of the higher antenna location. The above values apply to a particular experiment  in a particular location. Hence, the optimum antenna heights might vary. 
 To a first order, positive slopes (de- generative feedback) lower the guidance gain and lengthen the guidance time constant, making for a more sluggish response, while negative slopes (regen- erative feedback) raise the guidance gain and shorten the guidance time con- stant to the point where missile instability could occur. The guidance design must avoid such an instability. Target Illumination.6'13 Target illumination for a CW semiactive missile system can be provided by a CW tracking radar, a CW transmitter slaved to another tracking radar, or a pulse or pulse doppler tracking radar at another frequency with the CW illumination injected into the antenna system from a separate CW transmitter. 
 cc ¯     4HE AMBIGUITY FUNCTION OF  UT  IS DEFINED AS THE SQUARE MAGNITUDE OF THE AUTOCORRELATION  FUNCTION   9UD UDFF    \    \TC T     4HE AMBIGUITY FUNCTION IS INTERPRETED AS A SURFACE ABOVE THE DELAY 
 TRIBUTION AT ITS APERTURE 4HE VERTICAL AMPLITUDE DISTRIBUTION APPROXIMATES TO A COSINE BECAUSE OF THE HORIZONTALLY POLARIZED FIELD 6ERTICAL BEAMWIDTHS ARE TYPICALLY ABOUT  WIDE AT THE  D" POINTS .OT UNNATURALLY  COST  FOR A GIVEN PERFORMANCE  IS THE PRIME DRIVER IN THE SYSTEM  DESIGNERS CHOICE OF ANTENNA 7HILE THE CONVENTIONAL SLOTTED LINEAR ARRAY IS WIDELY USED  THERE ARE EXAMPLES WHERE DIFFERENT COST TRADEOFFS HAVE BEEN MADE &OR INSTANCE  THE USE OF A DIELECTRIC BLOCK MOUNTED DIRECTLY IN FRONT OF THE SLOTTED WAVEGUIDE ARRAY  IN PLACE OF THE FLARED SECTION  HAS BEEN USED AS AN ALTERNATIVE 4HE LEAKING ENERGY FROM THE TOP AND BOTTOM FACES OF THE DIELECTRIC BLOCK ADDS WITH ENERGY EMERGING FROM ITS FRONT FACE  GIVING FORWARD GAIN )T IS THE DEPTH DIMENSION OF THE DIELECTRIC BLOCK THAT DETERMINES THE GAIN  SOMEWHAT ANALOGOUS TO THE LENGTH OF A 9AGI ANTENNA 4HIS EFFECT REDUCES THE HEIGHT OF THE ANTENNA COMPARED TO A CONVENTIONAL DESIGN BY ABOUT A FACTOR OF THREE  TYPICALLY FROM ABOUT  MM TO  MM AT  '(Z 4HIS  MEANS THAT THERE IS  CONSIDERABLY LESS WIND 
 SPHERIC MOISTURE IN THE SURFACE BOUNDARY LAYER !IRBORNE RESEARCH RADARS PROVIDE MANY  OF THESE SAME CAPABILITIES WITH INCREASED COVERAGE AND GREATER MOBILITY 4HIS VARIETY OF  APPLICATIONS IN BOTH RESEARCH AND OPERATIONS ILLUSTRATES THE VITALITY OF METEOROLOGICAL RADAR  TECHNOLOGY AND ITS EVOLUTION 4HIS CHAPTER IS INTENDED TO INTRODUCE THE READER TO METEOROLOGICAL RADAR  PARTICULARLY  THOSE SYSTEM CHARACTERISTICS THAT ARE UNIQUE TO METEOROLOGICAL APPLICATIONS )N THIS REGARD  IT SHOULD BE NOTED THAT MOST METEOROLOGICAL RADARS APPEAR SIMILAR TO RADARS USED FOR OTHER PURPOSES 0ULSED DOPPLER SYSTEMS ARE FAR MORE PREVALENT THAN #7 RADARS  0RIMARILY  CENTER 
 ;\ significant improvement in power, efficiency, stability, and life over the  conventional magnetron is obtained when the straps are removed and the 1t mode is controlled  by coupling alternate resonators to a cavity surrounding the anode. This is known as a coaxial  moo11ctro11 since the stabilizing cavity surrounds the conventional resonators, as sketched in . 194 INTRODUCTION TO RADAR SYSTEMS  (a) (b) Figure 6.2 Magnetron resonators. 
 368–373, 2004. 120. R. 
 Biasedoperation isalsoknownasactiveandiscapableof switching highpower.43.44.62 BiasedPINdiodescanreplacethegas-tube TRsofthebalanced­ duplexer configuration ofFig.9.6ortheymaybeusedasreceiverprotectors. Forexample,44 a VHFbalanced duplexer configuration using32PINdiodesmounted inJA-inchcoaxialline(16 ineachoftwoSPSTshunt-type limiters) handled 150kWpeakpower,10kWaveragepower, withapulsewidthof200/lS.Atthefrequency ofoperation (200to225MHz),theuseof self-actuated diodeswaspractical. Recovery timewasrequired tobelessthan10/lS.Theloss ontransmit was0.15dBandonreceiveitwas2dB.(Thereceivelosscouldbereduced to IdBwithapplication ofreversebiastothediodes.)Thedeviceprovided from40to50dBof protection. 
 2  HTTPDIRECTORYEOPORTALORGINFO?2)3!42ADAR)MAGING3ATELLITEHTML HTTPDIRECTORYEOPORTALORGINFO?4AN$%-84ERRA3!28ADDONFOR$IGITAL%LEVATION-EASUREMENTHTML HTTPWWWMDACORPORATIONCOMNEWSPRPRHTM HTTPELIBDLRDE HTTPWWWGMESINFO4!",%  3YNTHETIC !PERTURE 2ADARS %ARTH 
 '-15 X 7.5  "-18x9  21 X 10.5  o.01.__~--'----'--'-'-...l..-1-'-'-.,__~-'---l'---'---'--'--'-'-'--'--~-'---.J ........ 1-1. .................. 
 Circuits for auxiliary functions such as pulse com- pression, clutter gating, synchronization, and TACCAR are not shown. With the exception of the interchange of the corporate-feed and duplexing functions, the transmit channel is identical to that of any other radar. An individual duplexer is placed between each corporate-feed output and its corresponding antenna ele- ment. 
 WHAT DIFFERENT NONLINEARITIES IN  ) AND 1  WHICH CAN GENERATE THE VARIETY OF SPURIOUS  DOPPLER COMPONENTS 4HE IDEAL INPUT SIGNAL IS   6! E )J 1 JTD    V    %ACH VIDEO CHANNEL RESPONSE CAN BE EXPRESSED AS A POWER SERIES &OR SIMPLICITY   ONLY SYMMETRICAL DISTORTION WILL BE CONSIDERED 4HE !$ OUTPUT  INCLUDING A RESIDUAL GAIN IMBALANCE OF $  IS   6g )1   6g)   J6g1      6g)   6)  
 1–7. ch19.indd   44 12/20/07   5:39:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 497 -498  Ferrimagnetic phase shifters, 29 1-297  Ferrite limiter. 264  Ferrite pfyse shifters, 291-297  Ferroelectric phase shifter, 297  Field-intensity pattern, 229  Filter bank: .  CW radar. 
 E  THE DESIRED VIRTUAL  DISTRIBUTION FUNCTION IS DISPLACED AHEAD OF THE APERTURE  AS SHOWN IN &IGURE B )N PRACTICE  PERFORMANCE IS LIMITED BY  THE ABILITY TO PRODUCE THE REQUIRED ILLUMINA 
 STRAIN OPPORTUNITIES FOR INNOVATIVE RADAR DESIGN  REMOVED THE REQUIREMENT THAT  '(Z RADARS BE COMPATIBLE WITH EXISTING RACONS 'ALLIUM .ITRIDE AND OTHER MICROWAVE POWER SEMICONDUCTORS   DEVELOPED PRIMAR 
 BAND  '(Z  !IRBORNE &IRE 
 White: Low-Frequency Approach to Target Identification, Proc  IEEE, vol. 63, pp. 1651-1660, December, 1975. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°{Ç SEEMED TO SHOW AN ENHANCED STRENGTH THAT CORRESPONDED TO THE SPECULAR POINT PASS 
 DENT AND SCATTERED MAGNETIC 
 Weconclude that, ifitisfound necessary tohave AFC onasystem with MTI, itshould be applied tothemagnetron rather than thelocal oscillator. Variation inmagnetron frequency from pulse topulse causes another kind ofeffect inthecase ofextended ground clutter. Consider two clutter signals that just overlap inrange. 
 These contours must be established for each particular geometric arrangement. A simple example is presented here: horizontal motion over a plane earth. This is typical of an aircraft in ordinary cruising flight. 
 13.42 except that adiode clamp (Vu) isillustrated forvariety inFig. 13.44. Tubes Vsa,VSb,and VCconstitute afeedback amplifier whose linear output current drives the deflection coil. 
 ERROR 
 The distinguishing factor between meteorological radar and other kinds of aviation  or military radars lies in the nature of weather targets, the resulting characteristics of  the radar signal, and the means by which these weather echoes are processed to sup - press artifacts and generate only the significant and essential weather information.  Important meteorological targets occupy a wide range of scattering echo intensities  (−20 to 70 dBZ) that are distributed in space from short range (< 1 km) to long range  (> 200 km), close to the surface (100 m) to the top of the atmosphere where weather  is important (20 km), and typically occupy a large fraction of the several millions  of spatial resolution cells observed by the radar. Moreover, it is necessary to make  quantitative measurements of the received signal characteristics in each of these cells,  or “weather targets,” to estimate such parameters as precipitation rate, precipitation  type, air motion, turbulence, and wind shear.19 In addition, because a high percentage  of radar resolution cells contain useful information, meteorological radars require fast  digital signal processors, effective means for suppressing artifacts caused by the data  density, high data-rate recording systems, and informative displays of this informa - tion. 
 Horst, and M. T. Tuley, “Predicting the performance of low-angle micro - wave search radars—Targets, sea clutter, and the detection process,” Proc. 
   PP n  *ULY   % (ANLE  h3URVEY OF BISTATIC AND MULTISTATIC RADAR v  0ROC )%%  VOL   PT &  PP n   $ECEMBER   - # *ACKSON  h4HE GEOMETRY OF BISTATIC RADAR SYSTEMS v  )%% 0ROC  VOL   PT &  PP n   $ECEMBER   $ % . $AVIES  h5SE OF BISTATIC RADAR TECHNIQUES TO IMPRO VE RESOLUTION IN THE VERTICAL PLANE v  )%% %LECTRON ,ETT  VOL   PP n  -AY     * 2 &ORREST AND * ' 3CHOENENBERGER h4OTALLY INDEPENDENT BISTATIC RADAR RECEIVER WITH REAL 
 !RT 'MB(  A CONSORTIUM OF ,OCKHEED -ARTIN -3 -OORESTOWN  .*   %!$3 $EUTSCHLAND 5NTERSCHLEISSHEIM  'ERMANY   4HALES !IR $EFENCE "AGNEUX  &RANCE   AND 4HALES 5+  ,IMITED #RAWLEY  7EST 3USSEX  %NGLAND   FOR THE -INISTRIES OF $EFENCE OF &RANCE  'ERMANY  AND THE 5NITED +INGDOM 6OLUME 3EARCH 2ADAR  4HE 3 
 Shock mounts can be used  to isolate components from the cabinet structure. It is recommended that all RF com - ponents, in their operational configuration, be tested for phase stability in the vibration  environment in which they will be used. Fact 1. 
 2“12and 2.15. Itshould benoted, however, that the numerical factors appropriate here arethesquare roots ofthose forradar signals, when for the latter the effects onboth the transmitted and reflected pulses are lumped together. These factors drop out ofthe expression (4)just astheantenna gains do,since they have thesame value forboth links. 
 4-1] RANGE, PRF,ANDSPEED OFSCAN 117 After each pulse transmission enough time must beallowed foreuergy totravel to,and return from, themost distant targets, thetime required forrange Rbeing 2R/c, ornearly 11psec foreach statute mile ofrange. Ifitissupposed that aradar setoperates with apulse-recurrence frequency of500 pps, during the 2000-psec interval following each pulse echoes will bereceived from objects within arange of186 miles. Atarget 250 miles away may, however, return asignal strong enough tobe detected. 
 V.I.:TheEffectsoftheTurbulent Atmosphere onWavePropagation, TT68-50464. Na­ tionalTechnical Information Service, Springfield. VA.1971. 
 With a cosine-on-a-pedestal  aperture illumination of the form An= a0 + 2a1 cos 2rrn/ N, the beamwidth is 18  0.886A [ ( )2] 08 :::::: --------1 + 0.636 1a 1 /a0 Nd cos 00 (8.1..t)  The parameter n in the aperture illumination represents the position of the element. Since the  illumination is assumed symmetrical about the center element, the parameter II takes on values  of 11 = 0, ± I, ± 2, ... , ± (N -1 )/2. 
 146–153, January 1990. 48. W. 
 23,  pp. 1577–1579, November 9, 1989. 25. 
 Radar Conf., London, October 1987. CHAPTER 6 REFLECTOR ANTENNAS Helmut E. Schrank Gary E. 
 3.1. Aspect Entropy Extraction Method at the Pixel Level In the SAR image, a pixel is the smallest unit, so it is reasonable to analyze the scattering anisotropy at the pixel level. The aspect entropy of pixels can be extracted by the method described below. 
 A compelling example is presented in Figure 20.42, where a range cell containing a  ship target traveling at a speed of 13 knots has been interrogated at eight radar frequen - cies and the resulting doppler spectra plotted in a nested display . The two columns of plots show received power versus doppler frequency for the  eight operating frequencies as labeled, and for the target approaching (right col - umn) and receding (left column). The abscissa units are in doppler normalized to GROUND WAVE PROPAGATION GRWAVE MODEL ILUKA DATAPOL = V NORMALISED AT 40 km ANTENNA  HEIGHT (m) 090100110120FIELD STRENGTH (dB)130140150 20 40 60 DISTANCE (km) REFRACTIVITY = 1.02  REL PERMITTIVITY = 80.00SCALE HEIGHT = 7.30  CONDUCTIVITY = 5.0080 100 120TX  0.0RX  0.0FREQ1 = 7.72 MHz FREQ2 = 12.42 MHz FIGURE 20.41  Experimental measurements of one-way surface wave attenuation,  compared with GRWA VE predictions. 
 vol.AES-IO. pp.25-33.January. 1974. 
 Thus  sr(t) = u(t _ To)e12rc(fo+/dHr-To) (11.47)  (The change of amplitude of the echo signal is ignored here.) With these definitions the output  of the matched filter is  ct)  Output= f u(t -To)ei2rc<fo+fdHr-To>[u(t -T~)ei2rcfo(r-Tii>J• dt  -ct)  = Jct) u(t _ To)u*(t _ T~)ei2rc(fo+fd)(r-To) e-j2rcf 0(r-Tii) dt  -ct) . J (11.48)  It is customary to set T0 = 0 and /0 = 0, and to define T0 -TR = -TR = TR. The output of  the matched filter is then  x(TR, fd) = Jct) u(t)u•(t + TR)e12xfJ, de -ct) ( 11.49)  In this form a positive TR indicates a target beyond the reference delay T0, and a positive /J  indicates an incoming target.13 The squared magnitude lx(TR,fd)l2 is called the ambiguicy  function and its plot is the ambiguity diagram. 
 (ILL    &IG    & % .ATHANSON   2ADAR $ESIGN 0RINCIPLES  .EW 9ORK -C'RAW 
                                 
 ch03.indd   31 12/15/07   6:03:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 
 22.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 22.4 TECHNOLOGY Antennas.  Antenna maximum sidelobes are specified for SOLAS and non- SOLAS radars in IEC 6238811 and IEC 62252,15 respectively. These are summarized  in Table 22.3. 
 A 50 ns pulse hardly achieves any period of stability—rise  times are normally restricted to about 10 ns in order to limit out-of-band interference,  FIGURE 22.3  Low-profile 3.9 meter S-band shipborne radar antenna ( Courtesy of Kelvin Hughes L td.) ch22.indd   12 12/17/07   3:02:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 
 NORMAL 4HE RESULT IS THAT THE MEAN ESTIMATED  R  & IS OFTEN MUCH  HIGHER THAN THE MEDIAN A FEW TARGETS  OR  D" HIGHER CAN RAISE THE MEAN A LOT EVEN THOUGH  THE TARGETS OCCUPY ONLY A TINY FRACTION OF THE AREA 4HUS  ONE SHOULD BE CAREFUL IN USING MEAN VALUES FOR RADAR DESIGN THE MEDIAN VALUES ARE MORE REPRESENTATIVE "ILLINGSLEY  PRESENTED HIS RESULTS BOTH IN TERMS OF MEAN VALUES AND MEDIAN VALUES  (ERE  WE REPORT ONLY THE MEDIAN VALUES BECAUSE THEY TEND TO BE MORE MEANINGFUL FOR RADAR DESIGN THAN THE VALUES DISTORTED BY OCCASIONAL STRONG TARGETS &OR MOST AREAS  LITTLE DIFFERENCE WAS FOUND BETWEEN VERTICAL AND HORIZONTAL POLARIZATI ONS  SO THE RESULTS WERE  REPORTED FOR DATA GROUPS INCLUDING BOTH POLARIZATIONS &IGURE  SHOWS THE RESULTS  GROUPED BY TARGET CLASS&)'52%     0HASE DIFFERENCES FOR DIFFERENT SURFACE CLASSES IN THE !MAZON BASIN AT # BAND AND , BAND  
 TO 
 Asaresult ofthe impedance transformation, the arc coupling (i.e., the power going tothe receiver asaresult ofthe voltage across the arc discharge) iswell below the danger point and isindependent ofinput power. There isasecond mechanism ofcoupling, called direct coupling, which gives leakage power proportional toinput power. Atthe higher transmitter powers, direct coupling becomes more important asasource ofleakage power than arccoupling. 
 If  similar equipment is used in the two types of radars, that is, the same antenna, same transmit­ ter, etc .. and if for the sake of analysis it is assumed that ab= am, Eqs. (14.35) and (14.36) show  that the echo signals from the monostatic and the bistatic radars will be equal when the target  is at the mid-point of the fence (R = D1 = D,). 
 236 INTRODUCTION TO RADAR SYSTEMS  determined hy the illumination of the line source, while the bcamwidth in the perpendicular  plane is determined by the illumination across the parabolic profile. The reflector is made  longer than the linear feed to avoid spillover and diffraction effects. One of the advantages of  the parabolic cylinder is that it can readily generate an asymmetrical fan beam with a much  larger aspect ratio {length to width) than can a section of a paraboloid. 
 The receiver fil- tering to be discussed here is that associated with separating a single pulse from interference, although the subsequent problem of filtering the train of echoes from a single target dictates the stability of the receiver filter. At some point in the radar receiver, a detector produces an output voltage which is some function of the envelope of the IF signal. If it provides a linear function, it is termed an envelope detector; logarithmic detectors will be de- scribed in Sec. 
 MONOSTATIC OPERATING POINTS %LSEWHERE  THE ISODOPS ARE NONSTATIONARY )N THESE NONSTATIONARY REGIONS  THE QUALITY OF BISTATIC 3!2 IMAGERY IS LIMITED AND MOVING TARGET INDICATION -4)  PERFORMANCE IS DEGRA DED WHEN USING STAN 
 SEC.17.15] AGROUND-TO-GROUND RELAY SYSTEM ~MauTat---l= ———— ——.— ——— .——.— ——— —— ----7 E===!Eh1-.!50mile flipflop I IAl IMTIvideoI IUpperbeamangle marksIB Video IRangemarks _Video Transmitter mixet switchI #1 I I Signalswitching andmixing#lL______ ––_–––-_i_– ––––––_iI rA~fT~m—s~aReT——————— ‘————————1 IModulator pulse /D I /Scaleof3E16PsecF Blinking delay oscillator I H I–_______ -____ YLaa_@u _____ –- IIUpparbeamvideo ~Beaconvideo I 1Rangemarks+-Duplexer ATransmitter #z‘+ , IUpperbeamanglemarksI Signalswitching andmixing #2I_. __—____— ——– ———. ———–––———–– J I MAzimuth DecoderI~muthdata. 
 A word of carttion sliould be give11 concerning the ability to achieve in practice low  sidclol~e levels wit11 cxtrcr~lcly tapered illutnil~ations. It was assumed in the cortlpittatiotl of  tlicse radiatiorl patterns that the distribution of the phase across the aperture was constant. In  a practical antenna this will tlot tiecessarily be true since there will always be some unavoid-  able pliase variations caused by the inability to fabricate tlie antenna as desired. 
 [ CrossRef ] 15. Xu, W.; Huang, P .; Wang, R.; Deng, Y.; Lu, Y. TOPS-mode raw data processing using chirp scaling algorithm. 
 Sometimes pulse compression radars have been called  spread spectrum radars. This terminology is misleading since pulse compression is used in  radar for different reasons than spread spectrum is used in communications.  11.6 CLASSIFICATION OF TARGETS WITH RADAR  In most radar applications, the only properties of the target that are measured are its location  in range and angle. 
 Focus Improvement for High-Resolution Highly Squinted SAR Imaging Based on 2-D Spatial-Variant Linear and Quadratic RCMs Correction and Azimuth-Dependent Doppler Equalization. IEEE J. Sel. 
 S. Reed, “Angle estimation with adaptive arrays in external  noise field,” IEEE Trans ., vol. AES–12, no. 
  RK\K IS THE FILTERED ESTIMATE OF THE TARGET RANGE  'STC   IS THE SENSITIVITY TIME CONTROL GAIN AND  3KJ IS THE NORMALIZED ANTENNA GAIN FOR THE  RECEIVED SIGNAL COMPUTED IN THE RADAR ACTIVE MODE "ECAUSE THE PHASED 
 Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar.  PULSE COMPRESSION RADAR  8.396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 is the range-rate (negative for an incoming target), c is the speed of light, and l = c/f0  (m) is the carrier wavelength. Matched Filters .2,74 A matched filter achieves maximum output signal-to-noise  ratio for a signal received in white noise. 
 73. Y . S. 
 (31) gives the radar cross section oftheground: a=(Ra)(~c7 sec8)Ksin0. (33). SEC. 
 A bar is a scan  segment along a single angular trajectory, as shown in Figure 5.20, later in the chapter.  Radar ModesPRF (kHz)Pulse Width (µsec)Duty Ratio (%)Pulse Comp. RatioFreq. 
 NOISE RATIO VERSUS RANGE DISPLAY SUPERIMPOSED WITH A CLUTTER 
 All this was combined with unreliable electronics, with units of the radar regularly going unserviceable, and general lack of experience among the operators and maintainers. It is not a surprise that operational performance was highlyvariable.Airborne Maritime Surveillance Radar, Volume 1 4-29. Following on from TRE Report T1863 [ 11], a further set of measurements of ASV Mk. 
 NOISE RATIO IS REDUCED BY THE USE OF WEIGHTING  ! THREE 
 Ó°ÎÈ  2!$!2 (!.$"//+  4HESE VELOCITY RESPONSE CURVES ARE CALCULATED FOR A SCANNING RADAR SYSTEM WITH   HITS PER ONE 
 It is usually a suitable  substitute for the short-pulse waveform except when a long minimum range might be a problem  or when maximum immunity to repeater ECM isdesired. Pulse compression radars, in addition  to overcoming the peak-power limitations, have an EMC (Electromagnetic Compatability)  advantage in that they can be made more tolerant to mutual interference. This is achieved by  allowing each pulse-compression radar that operates within a given band to have its own  characteristic modulation and its own particular matched filter. 
 The ground clutter itself acts asthereference signal, Modulator Transmitter TRI r I MixerStablelocal oscillatorMixer 1Signals Coherent Phaseshift Reference oscillatorReceiverunit signal (a)t Reference signalj, f.+fd ~c+~d_Phase.shifted fromcoherentMixer fc-f,Filterreference signal oscillator f. hDoppler frequency oscillator (b) FIG. 16.25 .—MTI on amoving system. 
 Ncrrl. Cot!/: Pt.oc.. .-l~,t.otru~rf. 
 0EAR SON  PROCEDURES AND ASSUMING THAT THE $& DETECTION ERRORS ARE USUALLY INDEPENDENT AND GAUSSIAN 
 68.Dixon,R.c.:"Spread Spectrum Systems," WileyInterscience, N.Y.,1976. 69.Newburgh, R.G.:BasicInvestigations oftheRADAM Effect,RomeAirDevelopment Cenrer,New York,ReportRADC-TR-78-151, June,1978,ADA058099. (Approved forpublicrelease.). 
 The 11ecff field and the fl'es11el regio11 have sometimes been called by antenna engin­ eers the rcactir·c 11car-jield region and the radiating near-field region, respectively.6  The farthest region from the aperture is the Fraunhofer, or far-field, region. In the Fraun­ hofer region. the radiating source and the observation point are at a sufficiently large distance  from each other so that the rays originating from the aperture may be considered parallel to  one another at the target (observation point). 
 (b)Sketch from map. 62). ,///“)4 Providenc~ (b) Fm.16.12 .—AN/APS-lO medium-altitude PPI. 
 JO  FT     2E[!E JO  FT]    2E[R E JP E JO  FT]   R 2E[E JO  FT P   ]   R COSO  FT P   4HE IMAGINARY PARTS OF THE  CONJUGATE SPECTRAL COMPONENTS HAVE C ANCELED TO REVEAL  THAT THOSE COMPONENTS TOGETHER INDEED REPRESENT A REAL SIGNAL   A SINUSOID WITH AMPLI 
 Actually this has not proved tobeaserious. 28 THERADAR EQUATION [SEC. !2.7 limitation down towavelengths oftheorder of3cm, because ranges that can beachieved arealready very great and arelimited usually bythe horizon rather than bythe relation expressed inEq. 
 The small array can also provide data on the coupling between elements. This data can be used to calculate the variation in impedance as the array is scanned. Both these techniques will be discussed later in this section. 
 The digital MTI processor depicted in Fig. 4.21 is that of a single-delay­ line canceler. Digital processors are likely to employ more complex filtering schemes, but the  simple canceler is shown here for convenience. 
 13.12 DIGITAL BEAMFORMING Many phased array radars use analog beamforming. In an analog beamformer, the  received signals from each element are combined at radio frequencies. At the output  of the analog beamformer, centralized receivers downconvert the signal from radio  frequency (RF) to an intermediate frequency (IF) and an analog-to-digital converter  (ADC) is used to digitize the IF signal. 
 BASED RADAR SOUNDERS MUST CHOOSE A FREQUENCY AND BANDWIDTH THAT BALANCE THE OFTEN CONFLICTING REQUIREMENTS OF PENETRATION  REFLECTIVITY  AND RESOLUTION  UNDER THE CONSTRAINTS OF AVAILABLE POWER AND ANTENNA APERTURE 4HE SPACE 
 Pulse compression  of the surface return generates range sidelobes which appear at depths that could easily  overwhelm the weaker reflections from the internal structure. The standard strategy  to mitigate this problem is rigorous sidelobe control, requiring severe pulse amplitude  weighting and strict control of phase and amplitude linearity. Due to the large footprint of a space-based sounder, and the need to salvage all  possible contributions of signals from depth, it is standard practice to assume that the  dominant in situ returns arise from specular scattering, hence from extended horizontal  layers.143 The contributing area is determined by the radius rF of the first Fresnel zone,  r hF= λ/2 in free space, where h is the altitude of the radar above the surface. 
 L/H FIG. 3.2 Downconverter spurious-effects chart. H = high input frequency; L = low input fre- quency. 
 18.13. The TE20-mode signals are added for the //-plane difference signal, the combined TE10 and TE30 modes are added for the sum signal, and they are sub- tracted for the E-plane difference signal. Since this is a focal-point feed, it is small in size (wavelengths) and RF currents tend to flow around the top and bottomFIG. 
 Passing squalls and rain showers did not wipe oul the duct or decrease  the propagated signals.  The thicker the duct, the lower the frequency that can he propagated, as can be seen from  Eq. ( 12. 
 Also shown are the velocity  responses of a five-pulse feedforward canceler and a three-pulse feedback canceler.  For the cancelers shown, the improvement factor capability of the three-pulse canceler  is about 4 dB better than the shaped-response four-pulse feedforward canceler, inde - pendent of clutter spectral spread. The five-pulse canceler response shown is a linear-phase28 MTI filter described by  Zverev.29 The four zeros are located on the Z-plane real axis at +1.0, +1.0, −0.3575,  and −2.7972. 
 408 INTRODUCTION TO RADAR SYSTEMS  For a bandwidth-limited "rectangular" pulse as described by Fig. 1 LS, the value of a:2 is ·  cos rr:Br -3 8(cos nBr -l) 2 sin rr:Br  rcBr (rr:Br)3 --(nBrf + Si (nBr)  Si (nBr) + (cos rrBr 1 )/nBr (11.30)  In the limit as Br -+ oo, the value of a2 approaches n2r2 /3, which is the same as that obtained  for the perfectly rectangular pulse.  The value of cx2 for a perfectly rectangular pulse is finite even though its value of p2 is  infinite. 
 J., and D. H. Temme: Phasers and Time Delay Elements. 
 With aloaded Qof350theTRtube isconsiderably off-tune atthe local-oscillator frequency, which isusually 30Me/see away from the signal frequency. Like allparallel resonant circuits, the TR cavity presents avery low impedance, practically ashort circuit, at frequencies offresonance. Iftheprobe were half awavelength from the coupling loop, itwould beeffectively atashort-circuit point forlocal- oscillator frequency and nopower could betransferred. 
 One of the attractive features claimed for a multiple-beam-forming  array is that it docs away with phase shifters. These are replaced, however, by multiple  receivers. one for each beam. 
 IRE Trarrs., vol. AP-4, pp. 51-53, January, 1956. 
 Significant fea - tures of this reflector include its precise surface accuracy, high stiffness and stability, low  mass, and reliable deployment. For example, for the reflector shown in Figure 12.38, an  RMS surface accuracy of less than 50 mils from all error sources including in-orbit ther - mal gradients was achieved via prudent material choices and matching of the associated  material coefficients of thermal expansion (CTEs). Pointing precision due to eclipse  thermal snap has been measured in orbit at less than 0.01 degrees.52PLATFORM DRIVES REFLECTOR ANTENNA MECHANICAL DESIGN Ground-based Ship-based Airborne Spaceborne Stowage/ Deployment•  Can be a driver  if system is  transportable.•  Typically not a  requirement.•  Typically not  a requirement,  but there are  exceptions.•  Typically required,  generally a major  design driver. 
 Switches were needed and type 458 transmitter switch and type 459 receiver switch were developed [ 2]. In March 1941 orders were placed for 200 complete switches. However, progress was slow, with many design and manufacturing problems and even by September 1942 problems were still beingencountered. 
 D. Howard, “Single Aperture monopulse radar multi-mode antenna feed and homing device,”  in Proc. IEEE Int. 
 Rept. WL1630.22, AD 51858, June 1970. (Not readily available.) 16. 
 For anantenna ofgiven size, thebeamwidth canbedecreased only bylowering thewavelength. The finite velocity oflight sets alimit tothedesirable beamwidth if aregion offinite size istobescanned atagiven speed byaradar set. Chapter 4considers this and other limitations ofpulse radar insome detail. 
 L. MacArthur: Digital Pulse Compression Radar Receiver, APL Technical Digest,  vol. 6, pp. 
 Moore, and A. K. Fung37) FIGURE   16. 
   PP n  !UGUST   & ! 3IKTA  7 $ "URNSIDE  4 4 #HU  AND , 0ETERS  *R  h&IRST 
  
 J. Wagner, “Refractivity estimation using  multiple elevation angles,” IEEE J. of Oceanic Eng ., vol. 
 FORM THROUGH A FREQUENCY MULTIPLIER THAT INCREASES BOTH THE OPERATING FREQUENCY AND BANDWIDTH OF THE CHIRP WAVEFORM &REQUENCY MULTIPLIERS MULTIPLY THE PHASE DISTORTION OF THE INPUT SIGNAL AND OFTEN HAVE SIGNIFICANT PHASE DISTORTION THEMSELVES $ISTORTION OF THE ,/ CHIRP SIGNAL PHASE CAN HAVE A SIGNIFICANT EFFECT ON THE COMPRESSED PULSE PERFOR 
 Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 14.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 If the surface is a good conductor, the total tangential electric field is virtually zero  and the total tangential magnetic field is twice the amplitude of the incident tangential  magnetic field:  n E× = 0 (14.11)  nn ni× =×HH 2 illuminated surfaces shaded surfacees (14.12) Note that the tangential components of both the electric and the magnetic fields  are set to zero over those parts of the surface shaded from the incident field by other  body surfaces. Other approximations may be devised for nonconducting surfaces. 
  AND SECOND 
 This report also introduced the concept of the matched filter, a contribution for which it had achieved some recognition prior to 1963. But except for the matched-filter concept, its contributions to signal detec- tion theory were virtually unrecognized by radar engineers generally until the re- port was republished 20 years after its first appearance. In a famous report3 first published in 1948 and republished in IRE Transac- tions on Information Theory in 1960, J. 
 44. Das, A., and J. A. 
 The assumed filter requirements are as follows: ● Provide a response of −66 dB in the clutter rejection notch (relative to the peak target  response) of the moving-target filters. ch02.indd   52 12/20/07   1:45:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 POSITION 
 621 cps Antenna Rotation  . up to 1 rpm, max Transmitter Tubes . 2 tridoes*** Receiver  . 
 614 helical scan. Alternatively, theantenna could besettorotate uniformly inazimuth, theelevation being manually controlled, orboth azimuth and elevation could bemanually controlled. The performance at10-cm wavelength was more than adequate togive the 60,000-yd range desired onsingle aircraft, and the convenience ofhaving acommon radar per- form both the search and the tracking functions isvery great. 
 However, the plateau which surrounds the spike is  more complex than illustrated in the simple sketch. With real waveforms, the sidelobes in the  plateau region can be higher than might be desired. Furthermore, the extent of the platform  increases as the spike is made narrower since the total volume of the ambiguity function must  be a constant, as was giveit'by Eq. 
 W. Shelton, Aspects of Radar Signal Processing , Norwood,  MA: Artech House, Inc., 1986. 137. 
 ING DAYLIGHT HOURS  BECAUSE THE CUTOFF FREQUENCY UNDER THOSE CONDITIONS INCREASED TO ABOUT  -(Z 4HUS  -!23)3 WORKED AS A SURFACE SOUNDER DURING DARK HOURS AND AS AN IONOSPHERIC SOUNDER DURING DAYLIGHT HOURS -ORE ON THE -!23)3 RADAR MAY BE FOUND IN 3ECTION  4HE  
 MENT OR DEPLOYED THAT UTILIZE SOME OF THE PULSE COMPRESSION WAVEFORMS PREVIOUSLY DIS 
 ·1~ampl_itud(!an<l e_~J-1.he-.signals..apP.Jied to each of the  elements arc controlled to obtain the desired radiation pattern from the combined action of all  the elements. Two common geometrical forms of array antennas of interest in radar are the  linear array and the planar array. A linear array consists of elements arranged in a straight line  in one dimension. 
   
 (2.46)] into the simple radar equation gives  where KI is a constant. The height h of the target is assumed constant, and sincc csc 4 = KIh,  the received power becomes  where K2 is a constant. The echo signal is therefore independent of range for a constant-  altitude target. 
 N. Sakura, K. Matsunage, K. 
  
 23. Taylor. J. 
 ALTITUDE TARGETS AT LONG RANGES BEYOND THE SURFACE HORIZON  WHERE THE  EFFECTS OF CLUTTER CAN BE IGNORED 5NDER THESE CONDITIONS  A SIMPLIFIED ANALYSIS STATES THAT RADAR PERFORMANCE IS RELATIVELY INSENSITIVE TO TRANSMITTER FREQUENCY AND WAVEFORM SHAPE IN PRACTICE  THE LOWER MICROWAVE FREQUENCIES ARE PREFERRED BECAUSE IT IS EASIER TO OBTAIN LARGE ANTENNA AND HIGH AVERAGE POWER AT LOWER FREQUENCIES  AND RAIN CLUTTER  IS NOT IMPORTANT 4HE MAXIMUM DETECTION RANGE ON A TARGET WITH  A CERTAIN 2#3  R  IN  FREE SPACE  FOR A SURVEILLANCE RADAR THAT MUST UNIFORMLY SEARCH A SPECIFIED VOLUME IN  A GIVEN TIME PERIOD  DEPENDS ON THE PRODUCT OF THE AVERAGE TRAN SMITTER POWER   0 AND  THE  EFFECTIVE ANTENNA APERTURE  !R  )T ALSO DEPENDS ON THE INVERSE OF THE SYSTEM NOISE  TEMPERATURE  BUT THIS IS OF LITTLE CONSEQUENCE SINCE THE NOISE TEMPERATURE IS NOT A MAJOR DESIGN ISSUE ANYMORE 4HE SITUATION IS MORE COMPLEX WHEN THE TARGET TO BE DETECTED IS OF THE STEALTH TYPE  7AVEFORM DESIGN AND OPERATING FREQUENCY ARE RELEVANT PARAMETERS IN TACTICAL AND  VOLUME SURVEILLANCE RADARS  WHICH MUST BE ABLE TO DETECT LOW 
 Raney, R. K.: Synthetic Aperture Imaging Radar and Movlng Targets, IEEE Trurrs, vol. AES-7,  pp. 
 Excellent installations arepossible iftheradar systems areconsidered in theinitial design studies ofaircraft. Since the airborne radome involves allthe problems ofthe surface- based installation inaddition tomany others peculiar toitself, this discussion will belimited totheairborne case. Some ofthefactors con- trolling the design ofanairborne radome arethe radar antenna and its 1Ssca 9,21-9.25 byF.J.Mehringer.. 
 OF 
 The video switch (Sec. 13.9) isarranged topass video signals only when theflip-flop (Sec. 13.7) ison,and pulses only when itisoff. 
 10.1)into the inductive portion ofone ofthe oscillators insuch away that itlinks the magnetic fhx. An r-fpotential difference isthus induced between the ends oftheloop, which areconnected totheinside and outside conductors ofthecoaxial line. This type ofoutput issatis- factory for magnetrons whose frequency is3000 Me/see orless. 
 The other is the  irltertsit~~-rrrod~~late~i CRT, such as the PPI, in which a target is indicated by intensifying  the electron beam and presenting a luminous spot on the face of the CRT. In general,  deflection-modulated displays have the advantage of simpler circuits than those of intensity-  modulated displays, and targets may be more readily discerned in the presence of noise or  interference. On the other hand, intensity-modulated displays have the'advantage of present-  ing data in a convenient and easily interpreted form. 
 Bristol, T. W.: Surface Acoustic Wave Devices-Technology and Applications. IEEE 1976 WESCON  Professional Program, Los Angeles, Sept. 
 "ASED -IDCOURSE $EFENSE '-$  PHASE OF THE -ISSILE $EFENSE !GENCY -$!  "ALLISTIC -ISSILE $EFENSE 3YSTEM "-$3  3"8S FLOATING PLATFORM  A MODIFIED OIL 
 The master oscillator provides a free-running, stable reference  sinusoid on which the system synchronization is based. Synchronizer.  The synchronizer distributes precisely timed strobes and clocks for  the various components of the radar system to ensure the time alignment of transmit  waveforms and the reception of their corresponding returns. 
 (4.6)] consists of a cosine wave at the doppler frequency& with an amplitude  2k sin nhT: Thus the amplitude of the canceled video output is a function of the doppler  frequency shift and the pulse-repetition interval, or prf. The magnitude of the relative  frequency-response of the delay-line canceler [ratio of the amplitude of the output from the  delay-line canceler, 2k sin (nfd T), to the amplitude of the normal radar video kj is shown in  Fig. 4.7. 
 There is no one universal transmitter best suited for all radar applications. Each power­ generating device has its own particular advantages and limitations that require the radar  system designer to examine carefully all the available choices when configuring a new radar  design. ·  The transmitter must be of adequate power to obtain the desired radar range, but it must  also satisfy other requirements imposed by the system application. 
 BEAM TARGET 4HIS CAN BE FOUND BY COMPARING THE 3. 2 VALUES  REQUIRED TO ACHIEVE A SPECIFIED  0 $ VALUE FOR THE RADAR SYSTEM WITH AND WITHOUT THE 3,"  , IS A FUNCTION OF MANY PARAMETERS SUCH AS  0$  0&!  &  '!  *.2  AND  A ! NUMERICAL  EVALUATION OF THESE PERFORMANCE PARAMETERS CAN BE FOUND IN THE LITERATURE SPECIFICALLY #HAPTER  OF &ARINA  AMONG OTHERSn  4HE 3," DESIGN REQUIRES THE SELECTION OF SUITABLE VALUES FOR THE FOLLOWING PARAME 
 The conventional receiver may he considered as comparing tlie HIL~LIII value of the 11 pulses  to a predetermined threshold. Trunk has shown that the trimmed-mean detector can be better  than either the mean or the median  detector^.^^.^' If there are 11 pulses available from which to  make a detection decision, the trimmed-mean detector discards the smaliest and the largest of  the 11 pulses before taking the mean. Although its performance may be good, it is difficult to  implement in practice because the 11 pulses must be rank-ordered to find the smallest and (lie  largest. 
 The multiple-band and steerable broadcast antennas reviewed in the IEEE Transactions on Broadcasting Special Issue on Short-Wave Broadcasting,11 those described in Johnson and Jasik,14 pages 26-29 through 26-35, and those given in "Shortwave Antennas,"15 Chaps. 13 and 14, are ex- amples. It will be noticed that many of the broadcast-service antennas employ large vertical apertures. 
 The range sum (RT + 7?^) can be estimated by two methods. In the direct method the receiver measures the time interval AT1,., between reception of the transmitted pulse and reception of the target echo. It then calculates the range sum as (RT + RR) = cbTrt + L. 
 175 Atmospheric attenuation, 459-461 Atmospheric noise.461-463 Attenuation inwaveguides. 57 Automatic detection. 183-184.388-392 Automatic detection andtrack(ADT).153, 183-186.392 Automatic gaincontrol. 
 OF 
 35. Bauer, J. R., and R. 
 In this paper, a novel ReBP–based SAR–SS is proposed based on the observation geometry of sliding spotlight mode. 4.2. The Modiﬁed Propagation Simulator for Sliding Spotlight Mode The propagation of transionospheric radio waves from the free space down to the ground follows the scalar Helmholtz equation which is expressed as ∇2E(ρ)+k2 0[1+Δεr]E(ρ)=0 (13) E(ρ)=U(ρ)·ejk·ρ(14) where k0=2π/λis the wavenumber corresponds to the signal frequency, Δεris the ﬂuctuation term of the dielectric permittivity mainly induced by the dispersive background ionosphere, E(ρ) is the electronic ﬁeld, U(ρ)is the complex amplitude and ρ=(x,y,z)is the space vector of the electromagnetic waves deﬁned in the geomagnetic coordinate as is shown in Figure 8. 
 Ê/"Ê1- 
 Hasselmann (eds.), New York: Plenum Press, 1986, pp. 285–292. 67. 
 SION PROCESS AND TO TRUNCATION DUE TO FINITE WORD LENGTHS IN THE SIGNAL 
 !PERTURE -OVING 
  
 Widrow and S. D. Stearns. 
 Such supports arestandard incoaxial lines used inthe 10-cm region and regularly have aVSWR less than 1.03 over abaad of~15per cent from the center frequency.. 396 RFCOMPONENTS (SEC. 11.2 The standard connector forjoining coaxial lines isshown inFig. 
  
 The so-called propagation window at 94 GHz is actually of greater attenuation than the attenuation at the water-vapor absorption line at 22.2 GHz. The millimeter-wave region is more likely to be of interest for operation in space, where there is no atmospheric attenuation. It might also be considered for short- range applications within the atmosphere where the total attenuation is not large and can be tolerated. 
 who did much of the early  work on crossc<l-f1eld devices.) In some crossed-field devices the sole does not emit electrons.  and a separate emitting cathode is used. The two words sole and cathode are sometimes used  interchangeably. 
 NATED AT THE FIRST NULLS  WAS ASSUMED 4HE SHAPE OF THESE CURVES  EXCEPT VERY NEAR THE  BLIND SPEEDS  IS ESSENTIALLY INDEPENDENT OF THE NUMBER OF HITS PER BEAMWIDTH OR THE ASSUMED BEAM SHAPE 4HE ORDINATE LABELED hRESPONSEv REPRESENTS THE SINGLE 
 A ﬁve-day average of the current ﬁeld data from 10 June 2010 to 14 June 2010 was considered. According to the above data, the wind speed near the eddy area is 2.1 m/s, the wind direction is 45◦, and the current velocity is 0.23 m/s. Therefore, αwas set to be 0.000657 according 319. 
 J. Caputi, “Swept-heterodyne apparatus for changing the time-bandwidth product of a signal,”  U.S. Patent 3283080, November 1, 1966. 
 Skolnik (ed.).  McGraw-Hill Book Company. New York, 1970. 
 ch20.indd   57 12/20/07   1:17:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 
 The total phase difference bisthen (25) Ifthe reflection atMistotal, both waves arriving at1?will have sub- stantially the same intensity, namely, that corresponding tofree-space propagation. 1Taking thephase difference into account, then F’=2(1+COS~). (26) The angle #,contained inO,depends upon the nature ofthe reflecting medium, upon theangle 0between thesurface and thedirection ofwave travel, and upon thepolarization. 
 the result added tothe airposition togive the ground position with respecb tothe point ofdeparture. Airposition and actual ground position both appear on the counter dials shown atthe lower left. The output signals ofthe unit can also beused toactuate aplotting arm which moves over amap table not shown inFig. 
 3ECTION !NALYSIS  .EW 9ORK !CADEMIC 0RESS    ( 7EIL ET AL  h3CATTERING OF ELECTROMAGNETIC WAVES BY SPHERES v 5NIVERSITY OF -ICHIGAN  2ADIAT  ,AB 3TUD 2ADAR #ROSS 3ECTIONS 8  2EPT  
 ther-ffield retards theelectrons. The electrons then give energy tothe cavity and thereby sustain the oscillations. Oscillation isobserved for more than one reflector voltage because drift times differing byawhole r-fcycle still produce satisfactory bunching. 
 Thereafter the normal OS- CFAR al- gorithm is applied to the “A” sum -value s:  For A=1, one gets the CA -CFAR (without free cell),  For A=2 and r=1 the CAGO -CFAR results (without free cell),   For L=1 the OS -CFAR results.  Moreover, between the CAGO -CFAR and the OS -CFAR any number of intermediate variants  is possible. With regard to the above techniques an optimal CFAR circuit would result if it  would be possible to create a circuit with thresholding at least as effective as that of the OS - CFAR, but with essentially lower processing power requirements. 
 $ ANTENNA GAIN USING SOLAR FLUX v .73 2/#  %NGINEERING "RANCH 2EPORT    % 'ORCUCCI  * 3CARCHILLI  AND 6 #HANDRASEKAR  h#ALIBRATION OF RADARS USING POLARIMETRIC TECH 
 ~-----_._-,._-- Ndcos00. 284 INTRODUCTION TO RADAR SYSTEMS  The half-power beamwidth is  0.8862 0,=0+ -0- z-- Nrl cos 6  Therefore, when the beam is positioned an angle O0 off broadside, the beamwidth in the plane  of scan increases as (cos Bo)- I. The change in beamwidth with angle 0, as derived above is not  valid when the antenna beam is too far removed from broadside. 
 tiley cannot be depended upon. Tlie extension of range along some propagation  paths means a decrease of range along others, or radio holes. These lioles in the coverage can  seriously affect airborne surveillance radars as well as ground-based and ship-borne radars. 
 Thisiscalled boxcarillg, orsampleandhold.Herethedeviceiscalledtheboxcargenerator. IIThebox.car generator wasalsomentioned inthediscussion oftheMTIreceiver usingrange-gated filters(Sec.4.4).Inessence,itclampsorstretches thevideopulsesofFig.5.4aintimesoasto covertheentirepulse-repetition period(Fig.5.4b).Thisispossible onlyinarange-gated receiver. (Tracking radarsarenormally operated withrangegates.)ThehoxcargenL:fator consistsofanelectriccircuitthatclampsthepotential ofastorageelement. 
 4  www.tektronix.com/radar   Continuous Wave and Pulsed  Radar   Radar  systems can use continuous wave  (CW) signals  or,  more commonly,  low duty -cycle pulsed signals.  CW radar   applications can be simple unmodulated Doppler speed  sensing systems such as those used by police and sports  related radar s, or may employ modulation in order to sense  range as well as speed.  Modu lated CW applications have  many specialized and military applications  such as maritime /  naval applications, missile homing, and radar altimeters . 
 The  number of beam positions multiplied by the dwell ~each equals the scan time. Long  dwell times and short scan time {high data rate) are not compatible. For example. 
 284 ANTENNAS, SCANNERS, AND STABILIZA TIOA’ [SEC. 9.12 data are transmitted asvoltages induced insynchros.’ There is,for instance, asynchro generator built into theAN/APQ- 13scanner shown inFig. 9.8which revolves 10times foreach azimuth revolution ofthe antenna; asynchro motor inthe indicator imitates the motion ofthe generator, and through agear reduction rotates the deflection coils of thePPI insynchronism with theantenna. 
   PP n  3EPTEMBER   6 ' (ANSEN AND " ! /LSEN  h.ONPARAMETRIC RADAR EXTRACTION USING A GENERALIZED SIGN TEST v  )%%% 4RANS  VOL !%3 
 Prabhu, K.M.M. Window Functions and Their Applications in Signal Processing ; CRC Press: Boca Raton, FL, USA, July 2014. 2. 
 L. Durden, E. Im, F. 
 Aspecial type ofbalancing machine has becm produced forthis purpose. ELECTRICAL SCANNERS BYC.V.ROBINSON Noradically new principles areembodied inthemechanical scanners discussed inthe previous section. By contrast, the electrical scanners tobediscussed inthe following sections have many novel features of fundamental design and somerit amore thorough discussion. 
  IS AN UPDATE TO THE !.403 
 13.12 provides anexcellent driving circuit forFig. 13.25b ifitisnecessary toprovide aspecial one. Ifaproper driving source isused, thefour-diode clamp can bemuch “tighter” than the two triodes inthe positive direction. 
 The RF signal is transmitted to a Single Pole Double Throw (SPDT) switch stage and then switched between two transmitting antenna modules, each one consisted of an eight radiating elements switched array. The reﬂected signal is received by four receiving antenna modules each one composed by four radiating elements switched array and then collected by the Radar sensor through a Single Pole 4 Throw (SP4T) switch stage.   Figure 4. 
 CAUSED SPECTRAL SPREAD AND PERIODIC MODULATIONS ! DELAY TIME IS PROVIDED TO SEPARATE THE BEACON RESPONSE FROM THE TARGET ECHO 4ARGET DOPPLER SCINTILLATION ALSO OFFERS USEFUL INFORMATION ABOUT THE TARGET CONFIGURA 
 A good ADT system therefore requires a  radar with a good_MTLand._ag.ood CEAR_.(.c_onstant false alarm rate) receiver. A clutter map,  generated by the radar, is sometimes used lo reduce the load on the tracking computer hy  blanking clutter areas and removing detections associated with large point clutter sources not  rejected by the MTI. Slowly moving echoes that are not of interest can also he removed hy the  clutter map. 
 VIC, based on ASV Mk. VI, was also operational [ 20]. This radar used the same waveguide feeds, under-wing scanners and waveguide switching as ASV Mk. 
 Mk VI Policy, RAF, File S.14403/6, Minutes of ‘A Special Meeting held in Room 71/II, Air Ministry, Whitehall, S.W.1, on Wednesday, 27th October, 1943, at 1545 hours ’ (TNA AIR 15/117) [2] Lovell B 1991 Echoes of War; The Story of H 2S Radar (London: Taylor and Francis) [3] Performance of A.S.V. Mk. VII (X band) in Wellington XIV Aircraft, C.C.D.U. 
 Double-sideband noise figures of 6.5 dB can be ob­ tained at 94 GHz, 8.5 dB at 140 GHz, and 11 dB at 325 GHz. (It has been suggested that a  7-dA single-sideband noise figure is achievable over these wavelengths.)73 Even lower noise  figures are possible with supercooled J.osephsonjunctions operating at liquid-helium tempera­ tures. There has also been significant development of high-gain antennas at millimeter wave­ lengths, especially for radio astronomy. 
 Pulse modulation can be common pulse-position modulation (PPM), indepen- dent pulse-width modulation (PWM), or pulse droop. In these cases, common modulation refers to in-phase modulation on both the transmitter pulse and the receiver range gate or transmitter blanking gate. Independent modulation occurs if only one of these pulses is affected. 
 Effective permittiv - ity for ground targets is very strongly influenced by moisture content since the relative  permittivity of liquid water is from about 60 at X band to about 80 at S band and longer  wavelengths, whereas most dry solids have permittivities less than 8. Attenuation is also  strongly influenced by moisture since wet materials usually have higher conductivity  than the same materials dry. Figures 16.3 and 16.4 show the effect of moisture content on  properties of plants and of soil. 
 Geophys. Res ., vol. 9(C2), pp. 
 STATE TRANSMITTER WAS BUILT DURING THE S TO REPLACE THE TUBE 4HE SOLID 
 -------~m (b)>­u c Q)5-fofL----"'-=------"'----::.....c-"-...:---t--:;:-:----7f""---.."""­ Q) Lu.. >-. U I!~·If------v,.-------...\../r---- m Time-. 
 J. Sletten, W. G. 
 18, no. I, June-  .luly. 1972. 
 Thefeedback mustbeeliminated ifthetraveling-wave amplifier istofunction satisfactorily. Energytraveling inthebackward direction maybereduced toaninsignificant levelinmost tubesbytheinsertion ofattenuation intheslow-wave structure. Theattenuation maybe distributed, oritmaybelumped; butitisusuallyfoundwithinthemiddlethirdofthetube. 
 The two-way attenuation of the radar signal in traversing the range R and  back is exp (- 2a R), where a is the one-way attenuation coefficient. If a is not a constant over  the path R, the total attenuation must be expressed as the integrated value over the two-way  path. J  Scattering from rain. 
  D"  WERE DEMONSTRATED FIRST IN THE S BY 7ESTINGHOUSE %LECTRIC #ORPORATIONS  !7!#3 !IRBORNE 7ARNING AND #ONTROL 3YSTEM  AND BROUGHT ABOUT TIGHT TOLERANCES IN CONSTRUCTION AND PHASE SETTINGS 4HE ADVENT OF MORE AND BETTER COMPUTER MODELING AND SOPHISTICATED TEST EQUIPMENT SUCH AS NETWORK ANALYZERS HAS LED TO IMPROVED METHODS OF DESIGNING WELL 
 SCAN PROBLEMS 3ECTION   (OWEVER  THE POTENTIAL FOR ENHANCING PERFORMANCE OF A COOPERATIVE MONOSTATIC RADAR AGAINST RETRO 
 Ridenour, L. N.: "Radar System Engineering," MIT Radiation Laboratory Series, vol. 1, McGraw-Hill Book Company, New York, 1947. 
 In one type of OTH radar design, a (rela-  tively) small transmitting antenna with broad azimuth beamwidth is used along with a large  rcccivir~g aperture consisting ol' a number of narrow co~~tiguous beams coveril~g the angle  illuminated by the wide transmitting beam. Thus the complexity of a large transmitting  antenna is traded for a nirmber of parallel receiving channels. It is also possible to utilize a  conlrnon aperture for both transmit and receive, with equal transmit and receive beamwidths. 
 DOPPLER 34!0 ARCHITECTURE.   !)2"/2.% -4)  Î°Î£ PLATFORM MOTION COMPENSATION )F ANTENNA AND RECEIVER CHANNELS ARE NOT WELL MATCHED   THE RESULTANT SUM CHANNEL BEAMS FORMED FROM DIFFERENT APERTURE ILLUMINATION FUNCTIONS &IGURE   WILL NOT BE MATCHED WELL ENOUGH TO PROVIDE MAIN 
 The deflection of the beam or the  appearance of an intensity-modulated spot on a radar display caused by the presence of a  target is commonly referred to as a blip.  ?'he focusing and deflection of the electron beam may be accomplished electrostatically,  electrornagnetically, or by a combination of the two. Electrostatic deflection CRTs use an  electric field applied to pairs of deflecting electrodes, or plates, to deflect the electron beam. 
 Blake, Radar Range Performance Analysis , Lexington, MA: Lexington Books, D.C.  Heath and Co., 1980. ch26.indd   28 12/15/07   4:53:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Skolnik (ed.), McGraw-Hill  Book Company, New York, 1970.  86. Mendez, A. 
 Design.andPerformance ofOver-the-Horizoll Radars.IIIC('I'/f<lcicl/lal ('OIl/t'r('II('(' RMJ..tR-77. pp.3640.Oct.252X.1977.lEE(London) Conr.Pub!.no.155. 22.Davies. 
 TheKalman fiIter78issimilartotheclassical ex-/3trackerexceptthatitinherently pro­ videsforthedynamical ormaneuvering target.IntheKalman fitteramodelforthemeasure­ menterror hastobeassumed, aswellasamodelofthetarget trajectory andthedisturbance or uncertainty ofthetrajectory.81 Suchdisturbances inthetrajectory mightbeduetoneglectof higher-order derivatives inthemodelofthedynamics, random motions duetoatmospheric turbulence, anddeliberate targetmaneuvers. TheKalman filtercan,inprinciple, utilizeawide varietyofmodelsformeasurement noiseandtrajectory disturbance; however, itisoften assumed thatthesearedescribed bywhitenoisewithzeromean.7SAmaneuvering targetdoes notalwaysfitsuchanidealmodel,sinceitisquitelikelytoproduce correlated observations. Theproperinclusion ofrealistic dynamical modelsincreases thecomplexity ofthecalcula­ tions.Also,itisdifficulttodescribe aprioritheprecisenatureofthetrajectory disturbances. 
 Spencer, and S. J. Anderson, “Stochastic constraints method in non station - ary hot clutter cancellation–part 1: Fundamentals and supervised training applications,” IEEE  Trans ., AES–34, no. 
 115v.400–2400 cps,340watts Direct current ........................,,,.27.5 v,80 watts Over-all system performance Transmitter frequency. 9375 f55Me/see Pulse power ................. 10kw Receiver sensitivity, search, 131 dbbelow 1watt Receiver sensitivity, beacon. 
 BASED SYS 
 AFCRC-TR-59-1I8(I), ASTIi\Document 211499,pp.8-17.April.1959.n.RUle.J.:physical Limitations onAntennas. MITResearch Lob.Electrollics Tech.Rept.248.Oct.20, 1952. ' 74.Wolff.I.:Determination oftheRadiating SystemWhichWillProduce aSpecified Directional Characteristic. 
 97. Foster, H. E., and R. 
 Barton, “Low-angle radar tracking,” Proc. IEEE , vol. 62, pp. 
 The use of t wo or more sequential CW signals, with a frequency offset of Δf, is also possible  (stepped frequency CW Radar).  7.2 FM CW -Radar   The simple CW Radar in section 7.1 is not in the position to clearly measure a range > λ/2 to  an object, since referencing timestamps  of any kind are not present over the entire signal.   These timestamps can be generated through the frequency modulation of the transmitting si g- nal. 
 2. To understand the basic concepts of different types of Radars for surveillance &  Tracking.   3. 
  ARE  APPLICABLE 4HE FILTERS CAN BE DESIGNED  IF THE TIME BUDGET OF THE PHASED ARRAY RADAR ALLOWS  TO UTILIZE MORE THAN THE FIVE PULSES PER COHERENT PROCESSING INTERVAL #0)  USED BY THE !32 
 D. K.: "Radars. vol. 
 PERFORMANCE &0'!S STORE THEIR CONFIGURATION IN VOLATILE MEMORY  WHICH LOSES ITS CONTENTS WHEN POWERED DOWN  MAKING THE DEVICES INFINITELY REPROGRAMMABLE &0'!S ALLOW THE DESIGNER TO FABRICATE COMPLEX SIGNAL PROCESSING ARCHITECTURES VERY  EFFICIENTLY )N TYPICAL LARGE APPLICATIONS  &0'! 
 Meas .,  vol. 40, pp. 1038–1041, 1991. 
 T. F. Busli, and P. 
 Ratio or mean-to-median cross section  for log-normal distribution = p. 52 INTRODUCTION TO RADAR SYSTEMS  performance for partially correlated pulses, interpolation between the results for the correlated  and uncorrelated conditions can be used as an approximation. A more general treatment  of partially correlated fluctuations has been given by Swerling.45 His analysis applies to a large  family of probability-density functions of the signal fluctuations and for very general correla­ tion properties. 
 D. S. Zrnic ′, “Estimating of spectral moments for weather echoes,” IEEE Trans. 
 TION #OURTESY OF 3CI4ECH 0UBLISHING  )NC  &)'52%   -INIMUM 02& FOR 3!2 4HE APPARENT LINE 
 OTHER RADAR TOPIC'S 565  (Fig. 14.15). (The attenuation in rain. 
 However, this is  usually not important since small changes in the probability of false alarm result in even  smaller changes in the threshold level because of the exponential relationship of Eq. (2.26).  Thus far, a receiver with only a noise input has been discussed. 
 The result can be expressed as: S(θ,f)=δp·rect((θ−ϕ)/θbw)·rect(f/Br)·exp[−j4π(f+fc)Rp/c] (5) where fis the current frequency in frequency domain after the spectral transformation of signal S(θ,tr), Bris the bandwidth. Since the echo signal has a shift-invariant characteristic in the azimuth direction, targets with diﬀerentϕhave the same form of range migration if they are the same distance from the rotation center. Therefore, for the convenience of derivation, in this paper, we assume ϕ=0. 
 to  I 1-.LT·: Fram 011 Aerospace a11d Electronic S_rste111s, vol. AES-3, no. 6, pp. 
 Natl. Conf on Aerona11t. Electronics (Dayton, Ohio). 
 32.Schultz, F.V.,R.C.Burgener, andS.King:Measurement oftheRadarCrossSectionofaMan,Proc. IRE,vol.46,pp.476-481, February, 1958. 33.Kelt,R.E.,andR.A.Ross:RadarCrossSectionofTargets, chap.27ofthe..RadarHandbook," M.I. 
 YEAR SOLAR CYCLE FORCES CHANGES TO SPECTRUM USAGE AND THE DENSITY OF USERS  WITH A RESULTANT IMPACT ON (& RADAR CHANNEL SELECTION !NOTHER TREND THAT HAS BECOME APPARENT IN RECENT YEARS IS THE GRADUAL REDUCTION IN (& USERS AS SERVICES MOVE TO SATEL 
 #ONTROLLED 4UBE  !LTHOUGH SOME MIGHT THINK THESE SHOULD HAVE DISAPPEARED  ALONG WITH THE OLD RADIO VACUUM TUBE  THERE HAVE BEEN MANY (&  6(&  AND 5(& RADARS THAT SUCCESSFULLY OPERATED WITH GRID 
  D"C %FFECTIVE NOISE LEVEL AFTER INTEGRATION $ISCRETE TO 4HERMAL .OISE -ARGIN 
 an MTI radar A-scope display (echo  amplitude as a function of time);  (f) superposition of many sweeps;  arrows indicate position of moving  targets.  the successive A-scope sweeps is shown in Fig. 4.3J The moving targets produce, with time, a  " butterfly" effect on the A-scope. 
 01–06. 33. G. 
 A 1'-23, 111'. 619 622. Septcr~lhcr. 
 Evans and T. Hagfors (eds.), New York: McGraw-Hill, 1968. 35. 
  
 DERIVED DATA GIVES BENEFITS TO NAVIGATION BECAUSE  OF THE COMPLEMENTARY NATURE OF THE TWO SYSTEMS 4HE RELATIVE RANGE AND BEARINGS OF A TARGET DERIVED FROM !)3 DATA ARE ENTIRELY INDEPENDENT OF THE RADAR MEASUREMENTS OF THESE PARAMETERS #LEARLY  ANY OBSERVED DIFFERENCES IN RADAR AND !)3 POSITIONS WILL THEN INDICATE AN ERROR IN SOME PROCESS  PROVIDED THE DIFFERENCES ARE OUTSIDE THE EXPECTED NOISE IN THE MEASUREMENTS 4HIS CAN BE HIGHLIGHTED FOR THE USER ! HIGH POSI 
 TRACK  WIDTH  HENCE THIS INEQUALITY REQUIRES THAT EACH RESOLVED ALONG 
 NOISE LEVEL AT THE !$ CONVERTER IS SET TO  QUANTA 4O FORM THE DOPPLER FILTERS   PULSES ARE COHERENTLY INTEGRATED 4!",%  .OTIONAL 3UBSYSTEM 0HASE .OISE !LLOCATION 3UBSYSTEM!LLOCATION!DJUSTMENT FOR  #OMMON 3OURCE ;D"= 2EQUIREMENT ;D"C(Z= 0ERCENTAGE D" 4RANSMITTER  
 This arrangement is known sae an  as a cathode-follower because the  cathode follows the grid-voltage  changes. If the resistor is made  sufficiently large the cathode =  voltage will rise very nearly as. FIG. 
 due to its quantized nature, that ultimately sets the limit to sensitivity as given by  Fq. (14.38). By scttingk'(. 
 12.7] AUTOMA TIC FREQUENCY CONTROL 455 inthesystem; these will bediscussed inthenext section. Inthesimplest type ofradar AFC, the integrated discriminator pulse output, suitably amplified, would godirectly tothereflector ofthelocal oscillator. This “hold in” type ofAFC requires manual tuning each time the radar is turned on. 
 contribute to cumulative radar system distortion. Distortion degrades system performance usually by increasing the sidelobe level and, in extreme cases, by reducing the SNR and increasing the pulse width. The paired-echo concept is useful in estimating distortion tolerances nec- essary to achieve a required time-sidelobe level.50 Pair 1 of Table 10.7 shows SIDELOBE LEVEL (decibels) FIG. 
 1IeMRB201Tellurometer iscapable ofmeasuring distances from200to250km, assuminr reasonable lineofsightconditions, withanaccuracy ofiO.5mi3 x10-6d, wheredisthedistance beingmeasured. Thetransmitter poweris2()(\mWandtheantenna isa smallparaboloid withcrossedfeedstomakethepolarizations ofthetransmitted andreceived. 98 INTRODUCTION TO RADAR SYSTEMS  signals orthogonal. 
 2%& AND  .%# 
 In [ 11], a dual-Delta factorization method was proposed to suppress sidelobes in squinted and bistatic SAR images, but this iterative method is complex and computationally expensive. This letter introduces a novel multi-pass squinted (MPS) SAR, whose data can be used to realize 3D imaging and also to produce 2D images with low azimuth sidelobes. Compared with traditional multi-pass SAR for 3D imaging [ 12] or multi-baseline SAR for interferometry [ 13], in which the SAR operates in broadside mode, MPS SAR works in squint mode and observes the scene with di ﬀerent azimuth squint angles on each pass. 
 The calculation of the improvement factor  can be performed by averaging the resultant residue power, obtained by summing the  signal phasors at specific values of q, from null to null of the antenna pattern. Figure 3.10 shows the effect of platform motion on the MTI improvement factor as  a function of the aperture displaced in the plane of the aperture per interpulse period Tp.  A 5.4% displacement reduces the double-delay improvement factor to 30 dB. 
 This is of course also an approxima- tion, but it is quite accurate at ordinary radar frequencies and temperatures. This matched-load power is called the available power.17 The concepts of available power, available gain, and its reciprocal, available loss, are assumed in all noise-temperature and noise-factor equations. These and other noise-temperature concepts are explained fully in Refs. 
 / 
 Afarsimpler model operating fixed-coil PPI’s and designed forless severe interference conditions has seen considerable successful service. The phase-shifted puke method isquite comparable tothe sine- cosine method ineffectiveness; itsmethod ofconverting tomechanical motion issomewhat simpler, and ithas considerably fewer adjustments. Since more data aretransmitted perradar cycle, greater protection against interference isprobably afforded. 
 DIGITAL!'#  AUTOMATIC GAIN CONTROL!-  AMPLITUDE MODULATION#!'#  CLUTTER AUTOMATIC GAIN CONTROL#&!2  CONSTANT FALSE ALARM RATE#.2  CLUTTER 
 It is more suited for tracking-radar applica­ tion than for surveillance radar.  The block diagram of Fig. 1.2 is a simplified version that omits many details. 
 On the  other hand, random errors differ from one antenna t(? the next even though they be of the same  design and constructed similarly. Therefore the effect of random errors on the antenna pattern  can be discussed only in terms of the average performance of many such antennas or in terms  of statistics.  The effect of errors on the radiation pattern has long bee"'\ recognized by the practical  antenna designer. 
 340 INTKODIJCTION TO RADAR SYSTEMS  77. Wheeler, H. A,: A Systematic Approach to the Design of a Hadia~or Element for a Phased-Array  Antenna, Proc. 
 AR-3D Mobile Air Defense Radar System, brochure, Plessey. 20. Pretty, R. 
 11.21 Normalized scattering width of an infinite, perfectly conducting cylinder for H polarization (incident magnetic field parallel to the cylinder axis). The normalization is with respect to the geometric optics return from the cylinder. sulator, its index of refraction is a complex function whose imaginary part gives rise to losses in the material. 
 McWhirter, “QRD-Based MVDR algorithm for  adaptive multipulse antenna array signal processing,” IEE Proc ., vol. 141, pt. F, no. 
 KADAR CLUITER 473  wldtll r rr, Eq. (13.8) is that of tile co~rt~resscd'~t~lse.)~~f the statistics of the clutter eclloes arc  s~rnilar to the statistics of receiver noise, then the signal-to-clutter ratio in Eq. (13.8) can be  selected sirnilar to that for sigrial-to-rloise ratio as described in Chap. 
 The setcan detect single heavy bombers toabove 30,000-ft altitude and 200-mile range, provided theaircraft areabove the horizon. The antennas aresimilar inthat each has ashaped cylindrical reflector 25ftlong, in11sections, fedbyalinear array ofdipoles atthe10- cmband and forming abeam 0.9° wide inazimuth. The waveguide trans- mission line isweatherproof, thearray being housed inaPlexiglas cover. 
  
 SIDELOBE TAPER TO MINIMIZE THE RETURNS FROM GROUND CLUTTER 4HE  3 BEAM IS USED FOR TARGET DETECTION AND  ACTING AS A SPATIAL FILTER    IS THE FIRST LINE OF DEFENSE AGAINST CLUTTER AND INTERFERENCE IN THE SIDELOBE REGION 4O FACILITATE TARGET TRACKING  ANGLE MEASUREMENTS WITH ACCURACIES FINER THAN THE ANTENNA BEAMWIDTH ARE USUALLY REQUIRED ! TECHNIQUE TO OBTAIN SUCH ANGLE MEASUREMENTS OF  A TARGET ON A SINGLE PULSE IS CALLED  MONOPULSE -ONOPULSE CAN BE CHARACTERIZED AS  AMPLITUDE OR PHASE  WITH PHASE BEING PREFERABLE DUE TO ITS ADVANTAGE IN ANGLE ACCURACY FOR A GIVEN SIGNAL 
 2.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 Antenna scanning also causes a spread of the clutter power spectrum due to the  amplitude modulation of the echo signals by the two-way antenna pattern.11 The result - ing clutter standard deviation is  σπfr r f nf n= ⋅ = ⋅ln.20265 Hz (2.15) where fr is the PRF and n is the number of hits between the one-way 3-dB points of the  antenna pattern. This equation was derived from a gaussian beam shape but is essen - tially independent of the actual beam shape or aperture illumination function used. The clutter spectral spread due to scanning, normalized to the PRF , is  σfTn=0265. 
 (This assumes that 0.-t /Oe and 0£ /0~  are integers, where O A is the total azimuth coverage and 0£ the total elevation coverage, such  that n ~ 8 A fh .) The antenna gain can be written as G = 4rr/00. With the above substitutions  into Eq. (2.54) the radar equation for a search radar becomes  R4 = PavAeO"Ei(n) ts  max 4rrkT0 Fn(S/N)i Ls n (2.57)  This indicates that the important parameters in a search radar are the average power and the  antenna effective aperture. 
 Hansen, I. D. Olin, and V. 
 AFCRC-TR-56-211. AD 98752.  101. 
 ADDED EFFICIENCY 0!%   AND GAIN  'N  0ERFORMANCE FOR  EACH IS REFERENCED TO  '(Z FOR #7 OPERATION 4HE 'A!S 0(%-4 OPERATES AT  6 THE 'A. (%-4 OPERATES AT  6 &ROM THESE PERFORMANCE CURVES  ONE SEES THAT THE SMALL SIGNAL GAINS ARE NEARLY IDENTICAL IN THE n D" RANGE  AS ARE THE LARGE SIGNAL EFFICIENCIES  BUT THE POWER OUTPUT CAPABILITY OF THE 'A. (%-4 IS  D" GREATER THAN FOR THE 'A!S 0(%-4 OF THE SAME SIZE ££°{Ê 
 I. Skolnik (ed.) McGcBw-Hill Book  Company, New York, 1970.  2. 
 74 PROPERTIES OF RADAR TARGETS [SEC. 38 ‘—-m—–-——” “,-:I LA~... ?’LJ_Because ofinterference, thereceived power varies between Oand 4times the po~ver received from one ofthetargets. 
 Broadband antennas can be gimballed or body-fixed. Since directional infor- mation must be determined on each received pulse, some form of monopulse an- tenna is required. Because the seeker may encounter any incident polarization, the antenna should have a uniform response to all senses of linear polarization.20 Four types of antenna systems are possible: an amplitude monopulse with four squinted beams, a three-channel phase-amplitude monopulse using four elements or apertures, an interferometer, and the two-channel polar monopulse using a four-arm dual-mode spiral.22 The first three are conventional configurations ex- cept that each of the antenna elements is a broadband device such as a log- periodic type, conical log spiral, or cavity-backed planar spiral. 
 TO 
 4. lky. J S., and S. 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 24.54  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 24.12 ECCM AND ECM EFFICACY There is a need for a quantitative measurement of the efficacy of one or more ECCM  electronic techniques when a radar equipped with these devices is subject to an ECM  threat. One performance measure generally used for an unjammed search radar is the  detection range of a certain target against a system noise background; this situation is  referred to as detection in clear environment . 
  
 1, table 6.2, and in Ref. 5, table 1.  Aperture blo~king.~-'~ An obstacle in front of an antenna can alter the aperture illumination  and the radiated pattern. 
 The JVC and  auction algorithms show much more gradual growth.  (after I Kadar et al.61 © SPIE.1997 ) FIGURE 7.34  Example of the use of multiple hypothesis tracking on 90 scans of simulated radar data  containing a single target and many false alarms: ( a) shows all hypotheses forms and ( b) shows the single  hypothesis selected. (Pruned hypotheses are grayed out.) ( after W. 
 .~  In addition to being used as the power tube for high-power radar systems, the travding­ wave tube has also been employed, at lower power levels, as the driver for high-power tubes  (such as the crossed-field amplifier), and in phased array radars which use many tubes to  achieve the desired high-power levels.  6.5 HYBRID LINEAR-BEAM AMPLIFIER  By combining the advantages of the· klystron and the traveling-wave tube into a single device it  is possible to obtain a high--power amplifier with a bandwidth, efficiency, and gain flatness  better than can be obtained with either the usual klystron or TWT.7 _One such device is the  Varian Twystron (a trade nam~), which is a hybrid consisting of a multicavity klystron input  section coupled to an extend~d interaction traveling-wave output section. The limitation to the  bandwidth of a klystron is generally the output cavity. 
 Reduced-bandwidth pulse compression processing is  performed if the reference waveform LFM slope is less than the transmit waveform  LFM slope ( aR < a  ). In both cases, the required processing bandwidth Bp is much  smaller than the waveform bandwidth.  Figure 8.29 shows the principle of stretch pulse compression for the case where the  LFM slopes of the transmit and reference waveforms are equal. 
 Navy eyes ‘growth plan’ for Super Hornet’s AESA radar,” Aerospace Daily  and Defense Report , December 6, 2005. 24. R. 
 W. Stimson, Introduction to Airborne Radar,  2nd Ed. Raleigh, NC: SciTech Publishing, Inc.,  1998, pp. 
 9.18  9.9 Signal-Processing-Related ECCM  .........................  9.19 9.10 Operational-Deployment  Techniques   .....................  9.21  9.11 Application of ECCM Techniques  ........................... 
 9. Merters, L. E., and R. 
 64, pp. 581-594, May 1976. 9. 
 STEP &OURIER METHOD TO THE NUMERICAL  SOLUTION OF NONLINEAR AND VARIABLE COEFFICIENT WAVE EQUATIONS v 3)!- 2EV      P     ! % "ARRIOS  h! 4ERRAIN 0ARABOLIC %QUATION -ODEL FOR 0ROPAGATION IN THE 4ROPOSPHERE v  )%%%  4RANSACTIONS ON !NTENNAS AND 0ROPAGATION   VOL   NO   PPn  *ANUARY   ' $ $OCKERY  h-ODELING ELECTROMAGNETIC WAVE PROPAGATION IN TROPOSPHERE USING THE PARA 
 It has been said43 that “a constant- efficiency amplifier has been a goal for transmitter engineers ever since Lee  DeForest and Ambrose Fleming invented the first electronic amplifiers.” This goal  seems to have been achieved by the CEA grid-controlled tube. It is customary to think of the shape of a conventional radar pulse as being  rectangular. It is seldom, however, perfectly rectangular with very short rise and  fall times because such a waveform has a very large bandwidth, as one can observe  from its Fourier transform. 
 TO 
 Then the fractional time during which thegrid ofVdbisreceiving signals through thedelay lineism. The probability that asignal from agiven undelayed pulse will overlap that from thedelayed pulses istherefore Zrm,thefactor 2entering onthe assumption that any overlap atallwill produce aresult. Thus the number ofreinforced signals reaching the grid ofVieach second is2n%. 
 iRE, vol. 36, pp. 1205-1214, October, 1948. 
 IEE RADAR 2002 , 2002, pp. 26–30. 78. 
 Rept. 8300, 1979.  3. 
 The size of the DEM image is M ×N. The coordinates of the pixel units are also indicated in Figure 8. Taking the pixel unit with coordinate ( θi,Rs j) as an example, we discuss the process of transforming the pixel unit from slant range to ground range. 
 In receive, the signal from each of the 56 subarrays is fed into a  receive beamforming network. The T/R module contains predriver, driver, and final transmit amplifiers, transmit/ receive switching, low-noise amplifiers, limiter, phase shifters, and logic control. The  T/R module block diagram is shown in Figure 11.22, and a photograph is shown in  FIGURE 11.22  Block diagram of the PA VE PAWS transmit/receive module shows a 1-2-4 transistor  driving configuration for the transmit amplifier and a quadrature splitter on the output to generate a polar - ized feed to the radiating element. 
 Slow processes, such as the 11-year solar cycle, seasonal changes,  and the diurnal cycle of the E- and F-layers can generally be treated as quasi-stationary  background processes that set up the ionospheric structure at any given time, within  which fast processes may occur. An exception to this classification arises with the  dawn and dusk terminators, that is, the day-night boundaries; sweeping around the  Earth at 1600 km/hr, they produce abrupt changes in the ionosphere and trigger large- scale instabilities. Structural Variability. 
   TACTICAL PRECISION 
 The product kT0 ~ 4 x 10-21 W/Hz. The purpose for  defining a standard temperature is to refer any measurements to a common basis of compari­ son. Equation (9.1) permits two different but equivalent interpretations of noise figure. 
 DELAY NETWORKS  THEN THE PHASE THROUGH THE TIME 
 436 INTRODUCTION TO RADAR SYSTEMS  Synthetic aperture radar. The syntheti<;: aperture radar, which is discussed in Sec. 14.1, is a  radar in a moving vehicle that provides a high resolution image in both range and in a  direction parallel to the vehicle motion. 
 MATELY  OR  CYCLES PER DAY DRIVEN PRIMARILY BY LUNAR AND SOLAR GRAVITY !S A RESULT  ALL TIDAL SIGNALS SENSED BY AN ALTIMETER ARE UNDERSAMPLED !LTIMETRIC DATA RETAIN THE RESULTING ALIASES  WHICH OVER THE COURSE OF A YEAR OR SO CAN BE IDENTIFIED  QUANTIFIED  AND CALIBRATED OUT !N ALTIMETERS ORBIT MUST BE CHOSEN SO THAT THE TIDAL ALIASES DO NOT GET CONFUSED WITH SIGNALS OF GEOPHYSICAL INTEREST 4HE 40 /RBIT 4HE STATE 
 From radar to target via reflection from the surface and return hy the same path  (AMB-BMA).  Path 1 is the shortest, path 4 is the longest and paths 2 and 3 are equal. Thus, there can be three  separate responses from a target, as illustrated in the idealized sketch of Fig. 
    HAS A SIGNIFICANT DISCREPANCY  AS POINTED OUT BY 3AILORS   SO IT SHOULD BE USED WITH CAUTION  4HESE  NOISE MAPS PROVIDE THE LEVEL THAT AN OMNIDIRECTIONAL ANTENNA WOULD RECEIVE %VEN THOUGH ASSUMING ISOTROPIC ##)2 NOISE HAS LIMITATIONS  IT DOES PROVIDE A REFERENCE LEVEL FOR INITIAL RADAR DESIGN ! NUMBER OF OPERATIONAL AND EXPERIMENTAL (& SYSTEMS HAVE ACCUMULATED THEIR OWN NOISE DATABASES AND COMPARED THEM WITH ##)2 MODEL DATA THE REPORT OF .ORTHEY AND 7HITHAM GIVES A DETAILED ANALYSIS  !N (& RADAR IS GENERALLY DESIGNED TO TAKE ADVANTAGE OF WHAT THE  ENVIRONMENT PER 
 A. Rugger: An Exact Expression for the Resolu- tion Cell Area in a Special Case of Bistatic Radar Systems, Trans. IEEE, vol. 
 A radonie permits a ground-based radar antenna to operate in tlie presence of high winds.  It ~11so preve~lts ice formation on the antenna. Although it is possible to design antennas strong  cr~ough to survive extreme weather conditions and to provide sufficiently large motors to  rotate them in high winds, it is often more economical to design lighter antennas with modest  drive power and operate them inside radomes. 
 If the radome surface absorbs moisture it can seriously degrade its performance in rain.  Cohen and Smolski 119 attribute most of the measured loss in the Bell Telephone air-inflated  radome at Andover, Maine to this effect. In immersion tests, the Hypalon-coated Dacron  fabric of the Andover air-inflated radome was found to absorb 13.2 percent water while the  fibrous glass-reinforced laminate of rigid radomes absorbed less than 0.5 percent. 
 Electron. Syst. 1999 ,35, 1240–1251. 
 If clutter is distributed more or less uniformly, the clutter echo will depend on the area illuminated by the radar resolution cell. Surface (ground or sea) clutter is described by the ratio of the clutter echo to the area illuminated by the radar. This normalized clutter coefficient is denoted a°. 
 The number ttt is  the secorld threshold to be passed in the double-threshold detector. The two thresholds must  be selected jointly for best performance. The optimum value of ni for a constant echo signal is  F!I~H'~I in Fig. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft.  MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 An aircraft using a data link is moving with respect to the other end of the link,  so the link geometry is continually changing in time, frequency, aspect, and attitude. 
 11.6CLASSIFICATION OFTARGETS WITHRADAR Inmostradarapplications, theonlyproperties ofthetargetthataremeasured areitslocation inrangeandangle.Suchradarsaresometimes calledblobdetectors sincetheyrecognize targetsonlyas"blobs" locatedsomewhere inspace.Itispossible, however, toextractmore information aboutthetarget.Radarmaybeabletorecognize onetypeoftargetfromanother; thatis,todetermine thatthetargetisa747aircraftandnotaDC-IO,orthataparticular ship isatankerandnotafreighter. Thiscapability isknownastargetclassification. Whenthetarget isaspacecraft orsatellite, theprocessissometimes calledSOl,orSpaceObjectIdentification. 
 B. Howard, and G. H. 
 ALTITUDE AIRBORNE MILLI 
 When a moderate number of pulses (5 to 16) are available, a binary integrator, a rank detector, or a moving-window integrator should be used. If the number of pulses is large (greater than 20), a batch processor or a two-pole filter should be used. If the samples are independent, a one-parameter (mean) threshold can be used. 
 The larger structures permit more  conservative design, with the result that coaxial magnetrons exhibit longer life and better  Electric Field-, __  lines  (TE011 mode) . Output  waveguide  cooducter Figure 6.3 Cross-sectional sketch of  the coaxial cavity magnetron. RADAR TRANSMITTERS 195  Figure 6.4 Photograph of the SFD-341 me­ chanically tuned C-band coaxial magnetron  for shipboard and ground-based radars. 
 Optical Flow Optical ﬂow is the apparent motion of objects in image sequences that results from relative motion between the objects and the imaging perspective. In one canonical optical ﬂow paper [ 30], two kinds of constraints are introduced in order to estimate the optical ﬂow: the smoothness constraint and the brightness constancy constraint. In this section, we give a brief overview of the optical ﬂow algorithm we employ in the proposed methodology. 
 Although the coherent detector may be of superior sensitivity than other detectors it is  seldom used in radar applications since the phase of the received signal is not usually known.  10.6 PERFORMANCE OF THE RADAR OPERATOR  J  The rate of information inherent in a typical radar signal is considerably greater than can be  handled by a human operator. A one-mevahertz-bandwidth signal, for example, is capable of  conveying information at a rate of two megabitsls, but an operator can accept an information  rate of only 10 to 20 bits/s. 
 BAND  2ADAR  "ACKSCATTER  -EASUREMENTS OF 7HEAT  "ARLEY AND /ATS   7AGENINGEN .ETHERLANDS #ENTER FOR !GROBIOLOGICAL  2ESEARCH    4 ,E4OAN  h!CTIVE MICROWAVE SIGNATURES OF SOIL AND CROPS SIGNIFICANT RESULTS OF THREE YEARS OF EXPER 
  ALTIMETER REPRESENTS THE STATE 
 15. Fay, F. A., J. 
                    .   2!$!2 $)')4!, 3)'.!, 02/#%33).'   Óx°£ DOWNCONVERTER AND AN EQUALIZATION FILTER %15 &)2  4HE EQUALIZATION FILTER IS TYPI 
 3.3). However, the difficulty of eliminating the leakage of the transmitter signal into the  receiver has limited the utility of unmodulated CW radar for many long-range applications A  notable exception is the Space Surveillance System (Spasur) for the detection of satellites 26.27  The CW transmitter of Spasur at 216 MHz radiates a power of up to one megawatt from an  antenna almost two miles long to produce a narrow, vertically looking fan beam. The receiver  is separated from the transmitter by a distance of several hundred miles. 
 ING RAINFALL RATE BY REFLECTIVITY MEASUREMENT ,HERMITTE  AND +OLLIAS ET AL GIVE AN  ANALYSIS OF -IE SCATTERING AND SHOW THAT IF THE SCATTERING IS PROPERLY ACCOUNTED  THE RAINFALL MEASUREMENTS ARE ACCURATE 0OLARIMETRIC RADARS MAY BE CONFIGURED IN DIFFERENT WAYS FOR DIFFERENT MEASURE 
 92.Cindrich. I..J.Marks.andA.Klooster: Coherent Optical Processing ofSynthetic Aperture Radar Data,Proc.Soc.Photo-Optical Instrumentation Engineers. vol.128,"Effective Utilization ofOpticsin RadarSystems." pp.12R143.1977. 
 Provencher, J. H.: Experimental Study of a Diffraction Reflector, IRE Trw1s., vol. AP-8. 
 4.4RANGE-GATED DOPPLER FILTERS Thedelay-line canceler, whichcanbeconsidered asatime-domain filter,hasbeenwidelyused inMTIradarasthemeansforseparating moving targetsfromstationary clutter.Itisalso possible toemploythemoreusualfrequency-domain bandpass filtersofconventional design inMTIradartosortthedoppler-frequency-shifted targets.Thefilterconfiguration mustbe morecomplex, however, thanthesingle,narrow-bandpass filter.Anarrowband filterwitha passband designed topassthedoppler frequency components ofmovingtargetswill"ring" whenexcitedbytheusualshortradarpulse.Thatis,itspassband ismuchnarrower thanthe reciprocal oftheinputpulsewidthsothattheoutputwillbeofmuchgreaterduration thanthe input.Thenarrowband filter"smears" theinputpulsesincetheimpulse response isapproxi­ matelythereciprocal ofthefilterbandwidth. Thissmearing destroys therangeresolution. If morethanonetargetispresenttheycannotberesolved. 
   
 F. R.Castella, “Analytical results for the x,y Kalman tracking filter,” IEEE Trans. Aerospace and  Electronic Systems , November 1974, vol. 
   -4) 2!$!2  Ó°Ó£ 4HE CLUTTER ATTENUATION AGAINST POINT CLUTTER BASED ON THIS DEFINITION WILL BE THE SAME  BEFORE OR AFTER PULSE COMPRESSION AND WILL ALSO BE IDENTICAL TO THE VALUE OF #! OBTAINED  AGAINST DISTRIBUTED CLUTTER WITH IDENTICAL SPECTRAL CHARACTERISTICS &OR THE PRACTICAL MEASUREMENT OF #! AGAINST A SINGLE PIECE OF POINT CLUTTER IE   CORNER REFLECTOR   THE TOTAL ENERGY MUST BE INTEGRATED  PER THE ABOVE DEFINITION  AT THE INPUT AND OUTPUT OF EACH DOPPLER FILTER 4HE CALCULATION OF THE ENERGY IS BEST PERFORMED PRIOR TO PULSE COMPRESSION SINCE THE PRECISE DURATION OF THE UNCOMPRESSED PULSE  AND THEREFORE THE INTEGRATION WINDOW  IS ACCURATELY KNOWN )F DONE  AFTER PULSE COMPRES 
 Physical device size: The size of a 24-mm periphery chip would be approx- imately 3000 square mils (75 mils by 40 mils). Larger chip areas decrease the probable assembly yield because assembly difficulty increases with larger chips, greater numbers of wires, and larger packages. 5. 
 23. Long, A. E., and D. 
  
 Otherreceiver techniques thanthelog-FTC werediscussed in Sec.10.7forachieving CFAR.Oneexample suitableforaclutterenvironment istheadaptil'e videothreshold (AVT)whichsetsthethreshold according totheamountofc1utth(ornoise) inanumberofrangecellsaheadofandbehindtheparticular rangecellofinterest. Thisform ofCFAR ispopular inautomatic detection andtrack(ADT)systemssinceitisnotstrongly dependent onthetypeofclutterandcanprovideCFARwithlandandweatherclutteraswell asseaclutter. Othermethods toavoidcluttersaturation. 
 As shown in Table 2, the azimuth resolution using the proposed method was 7.04% slightly higher than that for the rectangular window, at about 1.85 m. PSLR of the images weighted by rectangular window and Taylor window were−13.28 dB and−25.41 dB. ISLR of these two images were −10.11 dB and−20.18 dB, correspondingly. 
 When the target is at the azimuth center of the distance-isoline of the illuminated scene, θand fac become θcenand fdc,cen, respectively. Vis the aircraft velocity. λis the wavelength. 
 Birdsall, and W. C. Fox: The Theory of Signal Detectability, IRE Truns.,  no. 
 Siebert, W. McC.: A Radar Detection Philosophy, IRE Trans., vol. IT-2, pp. 
 Lett. 2016 ,52, 1950–1952. [ CrossRef ] 37. 
 NewYork,1%2. pp.98-100. 2.Wilmotty. 
 WAVE RADAR  USING SHORT INTEGRATION TIMES v 0ROC )NT #ONF 2ADAR   4OULOUSE    $ / #ARHOUN  * $ 2 +RAMER *R  AND 0 + 2ASHOGI  h!DAPTIVE CANCELLATION OF ATMOSPHERIC  NOISE AND IONOSPHERIC CLUTTER FOR HIGH FREQUENCY RADAR v -)42% 2EPORT  -42 "   3EPTEMBER   9 ) !BRAMOVICH  3 * !NDERSON  ! 9 'OROKHOV  AND . + 3PENCER  h3TOCHASTICALLY CON 
 J. Keeler and C. L. 
 31, pp. 25–39, 1996.  90. 
 2,624,876. issued Jan. 6, 1953. 
 Because some of the more complex functions in the generic  T/R module block diagram can be fabricated by using MMIC technology, the com - ponents that can be realized through the use of this technology can be employed to  create system architectures that are difficult, if not impractical, to design with other,  less integrated technologies. The MMIC design approach utilizes active and passive  devices that have been manufactured by using a single process. Active and passive cir - cuit elements are formed on a semi-insulating semiconductor substrate through vari - ous deposition schemes. 
 In principle, a radar can also measure the surface roughness of a target and determine something about its dielectric properties. Range. The ability to determine range by measuring the time for the radar signal to propagate to the target and back is probably the distinguishing and most important characteristic of conventional radar. 
 An early model of a Raytheon reflectarray gave  an ellipticity ratio of less than 1.5 dB with scans up to 30 °, corresponding to a theoretical  rain rejection of at least 15 dB. At the same time, an aircraft target would typically lose  approximately 3 dB, leaving a relative net improvement of 12 dB of rain rejection. Phased Arrays with Very Wide Bandwidth. 
 LIKE RESIDUE   THE USE OF )& LIMITING WAS ESSENTIAL FOR FALSE 
 63-70,  I>ccctnhcr, 1967.  2H. Kahiner. 
 7, pp. 104-106, Apr. 4, 1974. 
 PLER VELOCITY COORDINATES  BUT HIGH RESOLUTION USUALLY IMPLIES THAT THE RADAR HAS HIGH RANGE RESOLUTION 3OME HIGH 
 -IGRATION !LGORITHM 2-!  PROCESSING 3ECTION    )N ADDITION  FOR  CALCULATING CROSSRANGE RESOLUTION  THE SMALL 
 In some cases, out-of-band noise may  be added to whiten the A/D converter quantization noise and spurious signals. The out- of-band noise is then rejected through subsequent digital signal processing. The resulting SNR of the system after digital filtering with receiver bandwidth BR  and sample rate fs is given by  SNR dB SNR dBf BS RSYS ADC ( ) ( ) log = +  − 1021010 l log101+( )S SIF ADC (6.41) where SIF/SADC is the ratio of noise power spectral density of the A/D converter input  signal to the power spectral density of the A/D converter. 
 2. Phase-Comparison Monopulse. A second monopulse technique is the use of multiple antennas with overlapping (nonsquinted) beams pointed at the target. 
 F. Vetelino, T. J. 
 3.29  3.9 IF Limiters  ...............................................................  3.30  Applications  .......................................................  3.30 Characteristics  ................................................... 
 Where longer operation isrequired, very small two-cycle engines con- nected topermanent-magnet-field 400-cps generators have been developed bytheJacobsen Manufacturing Company, Racine, Wis., and theJudson Manufacturing Company, Philadelphia, Pa. Jacobsen produces aunit rated 125 watts 400 cps weighing about 13lb. Asingle-cylinder, air-cooled, two-cycle engine isdirect-connected. 
 TONE PULSE THAT PROVIDES COVERAGE TO  NMI AND A  
 Any use is subject to the Terms of Use as given at the website. Tracking Radar.  TRACKING RADAR  9.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 This discussion of target noise is based largely on aircraft, but it is generally appli - cable to any target, including land targets of complex shape that are large with respect  to a wavelength. The major difference is in the target motion, but the discussions are  sufficiently general to apply to any target situation. 
 At 15,000 feet a range  of some 400 miles is quite usual with Gee equipment,  and, of course, there can be no point in using wave-  lengths far removed from the customary 6 metres; there  can be no overloading, any more than there is limit to  the number of broadcast sets which can be tuned at any  one time to a B.B.C. transmitter. The standard fre-  quencies are sufficiently high to be immune from much  static and similar interference, and Gee can be used in  mountainous country with ease and accuracy. 
 The distance L between the transmitter and the receiver is called the baseline range or simply the baseline. The angles 0r and G^ are, respectively, the transmitter and receiver look angles. They are also called angles of arrival (AOA) or lines of sight (LOS). 
 ,  Visby, Island of Gotland, Sweden, 2004, pp. 67–73. 62. 
 Knittel, Artech House, Dedham, Mass.,  1972.  39. Lain. 
 If the values are obtained from dynamic (moving-target) measurements, they are usually time averages of fluctuating values; otherwise they are static values for a particular aspect. Since the instantaneous cross section of a target is a function of the aspect angle, targets that are in motion involving random changes of aspect have cross sections that fluctuate randomly with time, as was mentioned in Sec. 2.2. 
 Asimple diversity system might consist oftwo antennas respectively 75and 140 ftabove the sea, with arrangements forswitching the receiver tothe antenna providing the greater signal strength atany given moment. Ineffect, this reduces the depths ofthe cancellation minima ineither ofthe antennas considered separately. Future Trends inFrequency .—Frequencies most generally used for radar relay have been intheregion from onetoafew hundred megacycles per second, partly forreasons ofachievable power, higher gains ofnon- directional antennas, and soon. 
 With  Oboe it is possible for the same journey to be made over  entirely unknown country, and for the arrival spot to  be pin-pointed with an accuracy of yards. The original  plan was to develop Oboe with apparatus in the aircraft  or ship as simple as possible, and at a later stage of  development it was hoped that it might, in fact, be pos-  sible to dispatch the aircraft with no crew at all, the  Oboe being automatic.  Oboe is a responsor system, like so many radar  beacons; it does not depend on an echo from a distant  aircraft, but pulse transmissions from the ground sta-  tions, on arrival at a distant outfit, trigger it off and  cause a second pulse to be transmitted. 
 IEE (London), vol. 99, pt. IV, pp. 
 POLARIZATION COMPONENTS AND  IN AN !.&01 
 7.31. The one-axis  mount is the simplest. Most commercial marine shipboard radars used for navigation employ  such a mount. 
   PP n  !PRIL   , & &EHLNER  h4ARGET DETECTION BY A PULSED RADAR v 2EPORT 4'   *OHNS (OPKINS 5NIVERSITY   !PPLIED 0HYSICS ,ABORATORY  ,AUREL  -$   *ULY   $ 0 -EYER AND ( ! -AYER   2ADAR 4ARGET $ETECTION (ANDBOOK OF 4HEORY AND 0RACTICE    .EW 9ORK !CADEMIC 0RESS    * 6 $I&RANCO AND 7 , 2UBIN   2ADAR $ETECTION  .ORWOOD  -! !RTECH (OUSE  )NC    * 6 $I&RANCO AND 7 , 2UBIN   2ADAR $ETECTION   .ORWOOD  -! !RTECH (OUSE  )NC     PP n  $ ! 3HNIDMAN  h$ETERMINATION OF REQUIRED 3.2 VALUES v  )%%% 4RANSACTIONS ON !EROSPACE AND  %LECTRONIC 3YSTEMS  VOL   NO   PP n  *ULY    $ + "ARTON  h5NIVERSAL EQUATIONS FOR RADAR TARGET DETECTION v  )%%% 4RANSACTIONS ON !EROSPACE  AND %LECTRONIC 3YSTEMS  VOL   NO   PP n  *ULY   - %VANS  . (ASTINGS  AND " 0EACOCK   3TATISTICAL $ISTRIBUTIONS  RD %D .EW 9ORK  *OHN 7ILEY   3ONS  )NC    P   7 ( 0RESS  3 ! 4EUKOLSKY  7 4 6ETTERLING  AND " 0 &LANNERY   .UMERICAL 2ECIPES IN #  4HE !RT OF 3CIENTIFIC #OMPUTING   ND %D #AMBRIDGE  5+ #AMBRIDGE 5NIVERSITY 0RESS     PP n. 
 Fading-Rate Computations.  Doppler frequency calculation is the easiest way  to find fading rates. To compute the signal amplitude returned with a particular range  of doppler shifts, all signals having such shifts must be summed. 
 38. Skolnik. M. 
 MENT  ETC  FROM ' AP 4HESE LOSS FACTORS ARE DESCRIBED IN DETAIL LATER WITHIN THIS SECTION $IRECTIVE 'AIN AND &EED ,OSSES  $IRECTIVE GAIN OR DIRECTIVITY IS A MEASURE OF  THE PEAK POWER RELATIVE TO THE AVERAGE POWER RADIATED BY AN ISOTROPIC RADIATOR  IE  A RADIATOR THAT RADIATES ENERGY EQUALLY IN ALL DIRECTIONS $IRECTIVE GAIN CONSIDERS ONLY THE RADIATED POWER THUS  ANTENNA LOSSES SUCH AS FEED MISMATCH  FEED LOSS  AND WAVEGUIDE ANDOR CABLE LOSSES MUST ALSO BE CONSIDERED (OWEVER  THE RADAR ENGINEER TYPICALLY TABULATES THESE LOSSES SEPARATELY FOR USE IN OTHER RADAR CALCULATIONS !NTENNA DIRECTIV 
 For bodies with high-conductivity surfaces the scattering cross section can be calculated by using numerical methods.33 Facilities exist where good scale- model measurements can be made, and the Ohio State University compact range is an example.34 Rough but useful RCS estimates can be made by using the behavior of a few ''canonical" shapes. Figure 24.4 is a family of plots giving RCS versus radar fre- quency for an oblong-shaped conducting body. The straight line marked 90° X./2 dipole gives the RCS of a resonant, conducting half-wavelength rod, where the rod is parallel with the electric field. 
 Willey, “Space tapering of linear and planar arrays,” IRE Trans ., vol. AP-10, pp. 369–377,  July 1962. 
 Most radar antennas are linearly polarized; that is, the direction of the electric field  vector is either vertical or horizontal. The polarization may also be elliptical or circular.  Elliptical polarization may be considered as the combination of two linearly polarized waves  of the same frequency, traveling in the same direction, which are perpendicular to each other in  space. 
 P. H. Hildebrand, C. 
 FIGURE 12. 20 Reflector shaping FIGURE 12. 21 Elimination of blockage ch12.indd   20 12/17/07   2:31:26 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 ASPECT TARGET COVERAGE  THE TARGET IS POTENTIALLY COMPETING WITH SIDELOBE CLUTTER AT ALL ASPECTS  WHEREAS WITH HIGH 02&  A TARGET CAN BECOME CLEAR OF SIDELOBE CLUTTER AT ASPECT ANGLES FORWARD OF THE BEAM ASPECT &OR TARGETS WITH SUFFICIENT RADIAL VELOCITY  HIGH 02& IS TYPICALLY MORE EFFICIENT THAN  MEDIUM 02& 4HE TRANSMIT PULSE WIDTH IS USUALLY LIMITED BY THE TRANSMITTERS ABILITY TO PRESERVE THE PULSE AMPLITUDE AND PHASE CHARACTERISTICS OVER THE DURATION OF THE TRANSMIT PULSE &OR A FIXED TRANSMIT PULSE WIDTH AND PEAK POWER  A WAVEFORM WITH A HIGHER 02& WILL HAVE A HIGHER TRANSMIT DUTY CYCLE RESULTING IN A HIGHER AVERAGE TRANSMIT POWER &OR A GIVEN COHERENT PROCESSING TIME  MORE ENERGY IS PLACED ON THE TARGET  WHICH IMPROVES DETECTABILITY &OR THIS REASON  HIGH 02& IS USED FOR LONG 
 SUREMENTS MADE DIRECTLY ON THE CORRUPTED RADAR ECHO SPECTRUM 7HILE THIS APPROACH MAY BE RELATIVELY INSENSITIVE  TO SOME FORMS OF  CORRUPTION  IT IS NOT APPLICABLE TO SEAS  FAR FROM EQUILIBRIUM !LL THE METHODS FOR ESTIMATING SEA STATE OR SCATTERING COEFFICIENTS REQUIRE LONG  COHERENT INTEGRATION TIMES  USUALLY COMBINED WITH NONCOHERENT AVERAGING OF A NUMBER OF #)4S IN ORDER TO ACHIEVE A DISTINCT AND STABLE SPECTRUM 4HIS TYPE OF RADAR OPERATION WILL FREQUENTLY BE INCOMPATIBLE WITH OTHER RADAR MISSIONS "UT BECAUSE THE SEA ECHO IS GENERALLY A VERY LARGE SIGNAL  IT MAY BE OBTAINED WITH AN ADJUNCT OBLIQUE SOUNDER OPERATING IN AN APPROPRIATE RADAR MODE 3CATTERING  FROM  -ETEOR  4RAILS  AND  /THER  )RREGULARITIES  IN  THE  )ONOSPHERE  #LUTTER FROM IONOSPHERIC IRREGULARITIES SUCH AS THOSE MENTIONED IN  3ECTION  CAN SEVERELY LIMIT RADAR PERFORMANCE 5NLIKE THE TERRESTRIAL OR OCEAN ENVIRONMENTS WHERE VELOCITIES OF NATURAL SCATTERERS TEND TO BE LOW  THE IONOSPHERE IS HOME TO PHENOMENA WITH APPARENT SPEEDS OF  n MSn AND MORE  OBSCURING MUCH  OF THE RELEVANT DOPPLER DOMAIN WHERE MANMADE TARGETS MIGHT BE FOUND -ANY OF THESE SCATTERERS HAVE A TRANSIENT EXISTENCE  MUCH LESS THAN THE COHERENT INTEGRATION TIME  SO CONVENTIONAL SIGNAL PROCESSING CAUSES THEIR ECHOES TO APPEAR SPREAD IN DOPPLER  AS WELL AS DOPPLER SHIFTED 4HE GENERIC TERM  SPREAD 
 RANGE AIR 
 The statistics for the distribution of I3 for the three-pulse canceler for  hard-limited distributed clutter are shown in Figure 2.70.32 Note that for N = 20, less that 5% of the hard-limited samples have an improvement  factor less than 24 dB, whereas almost 60% of the samples exceed the  I3 expected for  a linear system. ch02.indd   60 12/20/07   1:45:17 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Inthe last frame (No. 0311 )and inthe enlarged frame (No. 0479, Fig. 
 FIGURE 25.29  Eight-stage CORDIC processorADD/SUB REGADD/SUB REG ADD/SUB REGADD/SUB REG ADD/SUB REGADD/SUB REG ADD/SUB REGADD/SUB REG CONTROLIin QinIout QoutPASS/INV REGPASS/INV REG0.607259 1 /2/2 /4 /4/128 /128 ch25.indd   25 12/20/07   1:40:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 
 100  11.5.1 Sphere .................................................................................................................... 100 . Radar System Engineering  Contents  iii     11.5.2 Circular Disks ....................................................................................................... 
 Kay, S.M. Modern Spectral Estimation: Theory and Application ; Prentice-Hall: Englewood Cli ﬀs, NJ, USA, 1988. 21. 
 Hwang, “Pulse compression for weather radar,” in IEEE Int. Radar Conf. ,  Washington, DC, 1995, pp. 
 3 2ANGE n n n n n n n n065 n n n n n n n n4&4! n n n n n n n n3EA 
 Sensors 2019 ,19, 1920 (detailed information can be found in [ 24]). Therefore, the predictor factor is set as 0.5 in our proposed KA-DBS algorithm. 3.3. 
 Conclusions at that stage were that sensitivity compared favourably with ASV Mk. III but was greatly inferior to ASV Mk V and Mk VI (ASV Mk V was a US S-band radar (ASG.1) ﬁtted in Liberator bombers). It was also found that the sensitivity of the radar varied greatly during the trials and also consistently deteriorated over the course of each trial (often by 5 or 6 dB, as measured by variations in the detection ranges of Grassholm Island). 
 Inthe first place, the ionosphere does not, toany appreciable degree, reflect orrefract microwaves. Inthe second place, the spreading of waves around the curved surface ofthe earth, essentially bydiflruction, ismuch reduced atmicrowave frequencies because the wavelength isso. 54 THERADAR EQUATION [SEC. 
 3 X 106  01 J-Lm . OTHER RADAR TOPICS 561  the effective application of electronic countermeasures. The short wavelengths allow narrow  beamwidths of high directivity with physically small antennas. 
 III. It was noted that the antenna achieved a VSWR of 1.3:1 or better, over wavelengthsbetween 9.05 cm and 9.15 cm, with a VSWR of 1.1:1 at 9.1 cm. It is likely that using waveguide rather than a coax feed would have reduced the microwave losses, as well as handling a higher power. 
 A relatjvely small  bundle of chaff can form a cloud with a radar cross section comparahlc to that of a large  aircraft.  Chaff is used either to deceive or to confuse. S1,ot chqf/'is thc name usually associated with  thc dcception role, while corridor clu~ff'is a confusion countermcasure. 
 Int. J. Appl. 
 UNIT VERSUS HEIGHT LINE WHERE THE SLOPE OF THE LINE IS NEGATIVE  - 
 Propagation Effects. Another topic in sea clutter that has been largely unex- plored is the role played by propagation effects within the atmospheric boundary layer lying over the sea surface. The effects of atmospheric absorption have been noted above in connection with millimeter-wave clutter. 
 1957.  108. Shelton. 
 2.7 applies for a single gulseQnly. However, many pulses  arc usually returned from any particular target (111cach radi~r scan and can he used to improve  detection. The number of pulscs111n)rcturncd from a point targeJ as the radar antenna scans  through its ~~~\~~-~j-~!!Jt is '/ ts,.\.. 
 19.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 Spectrum Moment Estimation.  A common Gaussian model of the mean  received power spectral density of a meteorological signal82 is depicted in Figure 19.5  and can be interpreted as follows. The received power is simply the integral under the  curve (the zeroth moment) and is given by  P S f df S v dvr= =∫ ∫( ) ( )  (19.33) where f and v are related by f = (2/l)v. 
 In Chap. 2 the receiver detection criterion was based on the  methods of Marcum and Swerling. Relationships between threshold levels, probabilities of  detection and false alarm, signal-to-noise ratio, and number of pulses integrated were obtained  using as a model a receiver with the following characteristics: (1) the envelope of the receiver  noise at the output of the IF filter was described by the Rayleigh probability density function  (pdf); (2) the envelope detector had either a linear or a square-law characteristic; (3) the  integrator consisted of a linear addition of the pulses in the video portion of the receiver; and . 
 A long pulse  return may be caused by a single large target, possibly an airliner, or multiple smaller targets clo sely spaced, possibly a  tight formation of fighter aircraft. Without sufficient resolution,  it is impossible to determine the number of objects that  actually make up the echo return. Narrow pulse width s  mitigate the  overlapping of echoes and improve resolu tion at  the expense of transmit power. 
 NOISE  SOLID 
 Its application to land  scatter was not far behind. The term Bragg scatter  is often used to describe the mechanism for the small- perturbation model. The idea comes from the concept illustrated in Figure 16.6 b. 
 30, Boston: AMS, 2003, pp. 199–214. 88. 
 18. Crombie, D. D.: Doppler Spectrum of the Sea Echo at 13.56 Mcs, Nature, vol. 
 Stand. Rept. 9178, 1966. 
 TERM STABILITY OF , 
 The noise power after passing through the atmos­ phere is kT,,B,JL. Thus the amount of power absorbed by the atmosphere is k'I;.B,.(l -1/L)  and is equal to the noise power tlN radiated by the atmosphere itself. From the definition of  effective noise temperature and the fact that 1/L is the" gain" (less than unity), the following  equation is obtained:  AN= kTeB11G-:-kiBn = k'1;,B11( 1 -~)  Hence Te= T.,(L 1) (12.15)  If the atmospheric loss were 1 dB at a temperature of 260 K, the effective noise tempera­ ture would be 68 K; a 3-dB loss results in Te = 260 K, while a 10-dB loss gives Te = 1340 K. 
 Radar System Engineering  Chapter 2 – EM Field Theory and Wave Propagation  10     These boundary conditions lead to total reflection with a shift in phase (r = -1) of the electroma g- netic waves of a perfect conducting body.  The direction of the reflection depends upon the inc i- dent angle and the geometry of the body. Complex bodies show a more complex reflection char- acteristic. 
 Keywords, such as the names of the mission, nationality, and radar, are usually sufficient to locate several refer - ences. Alert: Not all online resources are accurate; the reader is advised to seek out more than one and to verify  information by cross-comparison. ch18.indd   5 12/19/07   5:13:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Because of the sampled nature of the signals, the remainder of 1  the frequency band is also covered with similar response, but with ambiguity. A bank of filters,  as in Fig. 4.23, is sometimes called a cohere~~t ititegratior~ filter. 
 'ATED (IGH 02&  2ANGE 
 R. Leben, and R. A. 
 Efﬁcient Implementation of the K-SVD Algorithm Using Batch Orthogonal Matching Pursuit ; Technical Report; Computer Science Department, Technion: Haifa, Israel, 2008. 30. Horn, B.; Schunck, B. 
 49. J. Frank, “Phased array antenna development,” Johns Hopkins University, Appl. 
 LAYER SANDWICHES OF       OR MORE LAYERS   ARE SOMETIMES CONSIDERED WHEN GREAT STRENGTH  GOOD ELECTRICAL PERFORMANCE  AND LIGHTWEIGHT ARE REQUIRED 3OME OF THESE DESIGNS HAVE USED THIN LAYERS OF FIBERGLASS  &)'52%   #OMMON  RADOME 
   2USSIA  n 3  ,  0 -ULTIMODE 2)3!4  )NDIA  n # 6ARIOUS TO 1UAD4ANDEM 
  AND TRIANGULAR 
 The effect ofdoppler shift istoraise orlower the dotted curve (Fig. 5.12) corresponding tothe returned signal. With the proportions here used and with theaircraft inreasonably level flight, thedoppler frequency isalmost always less than the beat frequency due toaltitude; con- sequently the end result isthat there aresomewhat fewer cycles ofbeat frequency inone half ofthe modulating cycle, and somewhat more in theother, thetotal number percycle remaining thesame. 
 AP-15, pp. 552–559, 1967.  97. 
 PERIODIC BROADBAND ANTENNA 4HE LARGE CURTAIN ARRAYS OF THE FORMER 3OVIET RADARS USED HORIZONTAL DIPOLE ELEMENTS WHEREAS THE 53!& !.!03 
 Except for some naval applications for the detection of very  low-flying aircraft, the normal detection of aircraft over the sea does not usually represent a  severe MTI design'problem. Sea clutter is not as strong and does not usually extend to as great  a range as does land clutter. Thus high-flying aircraft over the sea can be detected at long range  with relatively conventional radar with only a minimal MTI, or even with no MTI in some  cases. 
 This was accomplished byusing stacked dipoles atboth the transmitting and receiving stations. These arrays had auniform horizontal pattern and some gain inthevertical plane. Associated ornear-by equipments often constitute aserious source of interference; consequently both antenna and power-line filters aredesira- bleatthereceiving station. 
   PP n  3EPTEMBER   , % "RENNAN  % , 0UGH  AND ) 3 2EED  h#ONTROL LOOP NOISE IN ADAPTIVE ARRAY ANTENNAS v  )%%%  4RANS  VOL !%3 
 Barton, D. K., and H. R. 
 Trapping, or ducting,  occurs when drrldh is greater than - 1.57 x m-'. The radar ranges with ducted propaga-  tion are greatly extended. Holes can also appear in the coverage. 
 Thus, being able to measure strong  precipitation echoes at short range and also weak precipitation echoes at long range  requires radar receivers having a total dynamic range of 90–95 dB whereas measuring  weak echoes in the presence of strong ground clutter requires as large an instanta - neous dynamic range (> 60 dB) as possible. More recent operational radars and most  research radars attempt to achieve the most sensitivity possible and can detect mini - mum reflectivity values of –40 dB Z or less at short ranges (e.g., 1 km). Operational radars in the past have employed sensitivity time control (STC) to  reduce gain at short range and compensate for strong nearby echoes; however, recent  radars tend not to use STC techniques since receiver dynamic ranges are adequate to  cover important weather echo intensities at the necessary ranges. 
 §S PULSE IS USED TO PROVIDE COVERAGE FOR TARGETS WITHIN  THE RANGE INTERVAL FROM  TO  NMI  3TRETCH 0ULSE #OMPRESSIONn  3TRETCH PULSE COMPRESSION IS A TECHNIQUE FOR  PERFORMING ,&- PULSE COMPRESSION OF WIDEBAND WAVEFORMS USING A SIGNAL PROCESSOR WITH BANDWIDTH THAT IS MUCH SMALLER THAN THE WAVEFORM BANDWIDTH  WITHOUT LOSS OF SIGNAL 
 TRAIN RADAR SIGNAL v  )%% 0ROC 
 The comparisons between sliding spotlight mode and stripmap mode are presented. In Section 4, a novel SAR-SS is proposed by considering the beam scanning of sliding spotlight mode. The reverse back-projection (ReBP) algorithm [ 28] is applied to generate the sliding spotlight mode SAR raw data. 
 Swerling: Adaptive Arrays, Micro\r.uc.e J., vol. 17, pp. 43 46, p. 
 This event cannot occur ifany ofthe pulses ismissing; therefore interference canproduce aresult only when three spurious pulses occur with approxi- mately thecorrect spacing. Differentiation attheinput circuit prevents. 688 RADAR RELAY [SEC. 
 REFLECTOR ANTENNAS  12.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 Reflector taper is often approximated by a radial amplitude distribution4  g(r) = 1 − r2 (12.13) where r is the radial distance normalized to the reflector radius and g(r) drops to zero  at the edge. The use of this taper function leads to a simple blockage loss equation:  P Pg r dr g r r drD D Gb mb m=∫ ∫2 01 2 012 20 2 2( ) ( )π π b b mb mGD D=2 2η (12.14) where h is the efficiency, as given in Eq. 12.10. 
 79 The greater the penetration into a rain­ storm, the more elliptical will become the polarization of an originally circular polarized wave.  Thus to maintain the improvement in rain cancellation with elliptical polarization, the polar­ ization on receive should be made variable with range (time). With such adaptive polarization  it has been suggested that an improvement in cancellation of 6 to 9 dB might be obtained  consisten!Jy. 
 BEAM TRACKING RADARS THAT MEET MISSILE 
 PULSE IMPROVEMENT FACTOR IS SHOWN &IGURE B 4HE EXPECTED THREE 
 to-noise-ratio cases. Zrnic*44 gives the following expression for the variance of the mean-frequency estimate /for the pulse-pair estimation technique and a gaussian-shaped spectrum vartf) - ^d^a'T+F+2?" - "'2751I (23-42) where p is the correlation coefficient and NIS is the noise-to-signal ratio. Equa- tion (23.42) applies to a single PRF with interpulse period T and assumes that all pulses in the interval J0 are used in the estimation algorithm. 
 If target images are to bepainted at their relative bearings as well as distances from the center of thePPI, the sweep must be rotated in synchronization with the rotation of the antenna. Just as the electron beam may be deﬂected radially by electrostaticorelectromagneticmeans,thesweepmayberotatedbythesamemeans.Thesweep is usually rotated electromagnetically in modern radars. As the antenna is rotated past the ship’s heading, the sweep, in synchronization with the antenna, is rotated past the 0˚ graduation on therelative bearing dial of the PPI. 
 DIGITAL CONVERSION  OUT 
 BAND CALIBRATION OF THE RECEIVERS THAT WILL SUPPORT THE ADAPTIVITY ON SEV 
 With other  phase arid freqiierlcy relationsliips, there is still a loss with a single chatinel MTI that car1 be  recovered by tlie use of both tlie 1 and (2 channels. An extreme case where tile blind pliase with  only a single channel results in a complete loss of signal is when the doppler frequency is half  the prf arid tlie phase relationship between the two is such that the echo pulses lie on the zeros  of the doppler-frequency sine wave. This is not tlie condition for a blind speed but nevertlleless  there is no signal. 
 fr=meanfrequency oftheclutterspectrum, fJ,=standard deviation ofclutterspectrum, fp=pulserepetition frequency. (FromAndrews.61). 142 INTRODUCTION TO RADAR SYSTEMS  in this fashion, the clutter frequency can be measured directly by sampling the received echo  signal over an interval of range. 
 Sensors 2019 ,19, 213 2.136×108, respectively. However, the computational complexity of the proposed method does not change qualitatively, and the real-time implementation of the EMAM onboard could be achieved after evaluating the existing hardware systems.       $]LPXWKSRLQWV  %DVLFPHWKRG ,0$0PHWKRG (0$0PHWKRG Figure 8. 
 pp. 1801 - 18 1 1, Noveniber, 1968.  104. 
 Hansen13 © IEEE 1970 ) ch07.indd   6 12/17/07   2:13:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 (Fig. 2.3). Tlie second detector and video amplifier are assumed  to form an envelope detector, that is, one which rejects the carrier frequency but passes the  niodulation envelope. 
 In the elevation plane, desirable radiation angles run between 0 ° and 40 ° for com - mon values of range and reflection height. The vertical beamwidth needs to be suf - ficient to illuminate the required range depth; in general, this is automatically satisfied  owing to the cost and complexity of an antenna able to form a beam narrower than  this in the vertical plane. For most scenarios, any sensitivity gained by directivity  in elevation directly improves radar performance, since instantaneous range depth is  generally limited by ionospheric effects. 
 5. The double-bounce signal.  Reflections frorri the landing gear can also cause errors. 
 CLUTTER  THE LIMITED RESTORATION THAT MULTI 
 gap asaswitching device was chosen. The rotary gap ismounted directly ontheshaft ofa400-cps alternator, which excites the network and isproperly phased bymechanical adjustment (Fig. 15.6). 
 Data spans of tens of sec­ onds are required to make that measurement. To per­ form an equivalent evaluation in orbit would involve a  data span of over 100 kilometers on the surface. With­ in the span, small-scale geoidal or oceanographic fea­ tures and possibly atmospheric effects will typically result  in an observed height variability that prevents centimeter­ level instrument precision from being verified. 
 Fano, R. M.: Signal-to-noise Ratios in Correlation Detectors, MIT Research Lub. Electronrcs Tech. 
 WINGED LOCUST      !RMYWORM MOTH      !LFALFA CATERPILLAR BUTTERFLY    (ONEYBEE WORKER      #ALIFORNIA HARVESTER ANT      2ANGE CRANE FLY      'REEN BOTTLE FLY       4WELVE 
 Off the  southern California coast. in the vicinity or San Diego, the boundary between moist and dry  air is relatively stable and exists at an average altitude of 300 to 500 meters. Since the elevated  duct is due to meteorological effects there are seasonal, as well as diurnal, variations. 
 Target returns that range correlate  inside the STC range, but fall below the STC threshold, are likely sidelobe discretes  and are blanked or removed from the correlation process (and kept from ghosting  with other targets). The basic logic is shown in Figure 4.13.45 Basically, the CFAR output data is  correlated (resolved) in range three times. Each correlator calculates unambiguous  range using M out of the N sets of detection data (e.g., three detections required  out of eight PRFs). 
 By designing the cold cathode as a slow-wave circuit and introducing the RF drive al  the cathode emitting surface itself, it has been possible to achieve about 30 dB of gain in a  high-power pulse CF A with power, bandwidth, and efficiency commensurate with conven­ tional designs.43 The RF output is taken from the anode slow-wave circuit. Thi6 type of device  has been called a cathode-driven CF A 6 or a high-gain CF A. 19  The type of crossed-field amplifier principally considered in this section can be described  as a distributed emission, or emitting sole, amplifier with a reentrant, circular format utilizing  a forward-wave interaction without feedback. 
 The single exception is the  two-pulse MTI canceler,19 which provides optimum performance for all target dopplers. A more attractive approach for designing an optimum MTI filter is to maximize  its improvement factor (or clutter attenuation). To design an optimum MTI filter using  improvement factor as the criterion, the covariance matrix of the clutter returns, as given  by Eq. 
 Onerotary jointpermitsmotioninazimuth; theother,inelevation. Radar Fi~ure5.2Conical-scan tracking.. Tn rntn  o ,,,ry joint  on antenna ,to,. 
 Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22   blind folio 22.36 ch22.indd   36 12/17/07   3:02:41 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 A false alarm may be manifested as a momentary blip on a cathode ray  tube (CRT) display, a digital signal processor output, an audio signal, or by all of these means. If the  detection threshold is set too high, there will be very few false alarms, but the signal -to-noise ratio  required will inhibit detection of valid ta rgets. If the threshold is set too low, the large number of false  alarms will mask detection of valid targets. 
 M. Staudaher, “Airborne MTI”; W. H. 
 For an array with four thousand elements, a  three-hit rhase shifter will give rrns sidelohes better than 47 dB below the main beam, and a  four-hit phase shifter gives 53 dB sidelobes. Thus three or four bits should be sufficient for  most large arrays. except where very low sidelobes are desired. 
 Three range-only monostatic radars combined in a radar net are sometimes called a trilateration radar. The trilateration concept applies to multistatic radars that measure target location by time-difference-of-arrival (TDOA) or differential doppler techniques. The foregoing definitions are broad and traditional1'15'16 but are by no means uniformly established in the literature. 
 The relatively wide range of frequencies available at X band and  the ability to obtain narrow beamwidths with relatively small antennas in this band  are important considerations for high-resolution applications. Because of the high fre - quency of X band, rain can sometimes be a serious factor in reducing the performance  of X-band systems. Ku, K, and Ka Bands (12.0 to 40 GHz). 
 Hlcvis. R. C.: Losses Due to Rain on Radomes and Antenna Reflecting Surfaces, IEEE Trans .. 
 33); Technische Universität Darmstadt, Fachbereich Bauingenieurwesen und Geodäsie: Darmstadt, Germany, 2010. 6. Atzeni, C.; Barla, M.; Pieraccini, M.; Antolini, F. 
 3HALOM AND 4 % &ORTMANN   4RACKING AND $ATA !SSOCIATION   .EW 9ORK !CADEMIC 0RESS   *ANUARY   3 " #OLEGROVE AND 3 * $AVEY  h0$!& WITH MULTIPLE CLUTTER REGIONS AND TARGET MODELS v  )%%%  4RANS !%3  VOL   PP n  *ANUARY .   (& /6%2 
 1069–1076, 1998. 120. G. 
 BEAM NOISE JAMMING CAN BE REDUCED WITH HIGH RADAR FREQUENCY (IGHER FREQUENCY RADARS TEND TO HAVE NARROWER ANTENNA BEAMWIDTHS AND LARGER OPERATING FRE 
 1.2a. The phase shifters are electronically actuated to permit rapid scanning and are adjusted in phase to a value between O and 2ir rad. With an interelement spacing s, the incremental phase shift i|i between adjacent ele- ments for a scan angle 60 is i|* = (2ir/X)5 sin 60. 
 TIONS IN AN INDIVIDUAL CONVECTIVE STORM  CELL 3HOWN ARE THE HORIZONTAL VECTOR FIELDS IN  A PLANE APPROXIMATELY  M ABOVE THE SURFACE 4HE PHENOMENON B EING MEASURED IS  A LOW 
 Two-cut miter elbows, such asthose shown inFig. 11.1 lb,are well matched ifthe distance between cuts, measured along the center ofthe guide, isaquarter ofthe guide wavelength. Flexible waveguide can be made bywinding Itupout ofmetal strip inthe same way that certain. 
 Therefore, to penetrate 10 miles  within the diffraction region, the radar power at 500 MHz must be increased by at least 20 dB  over that required for free-space propagation.  The decrease in radar coverage due to the attenuation of electromagnetic energy in the  diffraction region is illustrated by Fig. 12.8 for a radar operating at a frequency of 500 MHz. 
 POWER 474S IS CALLED VELOCITY TAPERING 4HIS TECHNIQUE CONSISTS OF TAPERING THE LENGTH OF THE LAST FEW SEC 
 19.10 Antiradiation homing (ARH) receiver. A typical configuration is shown, including a dual-mode spiral antenna, high first IF, switchable bandwidths, and compressive (microscan) CW processing. (From Ref. 
 ING THE CONTOURS OF CONSTANT DOPPLER SHIFT ISODOPS  ON THE SCATTERING SURFACE 4HESE CONTOURS MUST BE ESTABLISHED FOR EACH PARTICULAR GEOMETRIC ARRANGEMENT ! SIMPLE EXAMPLE IS PRESENTED HERE HORIZONTAL MOTION OVER A PLANE EARTH 4HIS IS TYPICAL OF AN AIRCRAFT IN ORDINARY CRUISING FLIGHT #ONSIDER TRAVEL IN THE  Y DIRECTION  WITH  Z VERTICAL AND THE ALTITUDE FIXED   Z   H  4HEN  V 2   
 Other  attractive features are lower prime power requirements and lower costs for the PBR.2 While a PBR can exploit both cooperative and noncooperative broadcast trans - mitters, the PBR has no control over their transmission or waveform properties,  specifically the transmission schedule, effective radiated power, spatial coverage,  modulation type, modulation content, and resulting autocorrelation function, as out - lined earlier. Furthermore, interference from the host emitter and other emitters, espe - cially in urban and suburban areas, can significantly degrade PBR performance. This  section summarizes the problems and remedies encountered by a PBR exploiting  these broadcast transmitters. 
 For best performance, the velocity of  the surface wave should be very close to that of free space. If the array contains wave - guides or horns loaded with dielectric, the velocity will decrease slightly. Further, if  the dielectric protrudes from the radiators or if a dielectric sheet is used in front of the  array, the velocity of the surface wave may decrease dramatically. 
 UMN  AND RECEDING LEFT COLUMN  4HE ABSCISSA UNITS ARE IN DOPPLER NORMALIZED TO   # %$    "    %$  #"  $   !" )*  "   "* !"  "(        !" )*   "$"'    ""$"' 
 The original signal and the newly merged signal of one range cell in the slow time and the spectrum domain ( a) Original echoed signal in the slow time domain; ( b) The newly merged (predicted signal plus original signal) signal based on the spatial continuity property; ( c)Spectrum of the original echoed signal ( d); Spectrum of the newly merged signal. The corresponding spectrum information can be found in Figure 3c,d, respectively. The zoomed in spectrum information about this two targets is left-top of the Figure. 
 Watts, H. D. Griffiths, J. 
 Attenuator control unit 448 (marked as A) in a Wellington XIV [ 1].Airborne Maritime Surveillance Radar, Volume 1 4-7. 4.2.7 Indicator unit type 162B The main changes to indicator unit type 162B from type 162 used on ASV Mk. III were related to the removal of the local oscillator. 
 Theintegration-improvement factor(ortheintegration loss)isnotasensitive function ofeithertheprobability ofdetection ortheprobability offalse alarm. Theparameter nfforthecurvesofFig.2.8isthefalse-alarm ll/lmoa, asintroduced by Marcum.tOItisequaltotheredprocal ofthefalse-alarm probability Pradefinedpreviously by Eqs.(2.24)and(2.25).Someauthors, likeMarcum, prefertousethefalse-alarm number insteadofthefalse-alarm probability. Ontheaverage, therewillheonefalsedecision 0111ofIII possible decisions withinthefalse-alanri timeTea.Thustheaveragenumber ofpossible deci­ sionsbetween falsealarmsisdefinedtobenf'Ifristhepulsewidth,Tpthepulserepetition period,andfp=IITpisthepulserepetition frequency, thenthenumberofdecisions Ilfintime 1(aisequaltothenumber ofrangeintervals perpulseperiod,., =Tp/r=l/fprtimesthe numberofpulseperiodspersecondfp, timesthefalse-alarm timeTra.Therefore, thenumberof possible decisions is1If=1(afptl=1(a/r.Sincer:::::liB,whereBisthebandwidth, thefalse­ alarmnumber is11f=1(aB=11Pra. 
 BIT !$# PROVIDES ABOUT  D" OF DYNAMIC RANGE  ASSUMING !$# NONLINEARITIES ARE NEGLIGIBLE ! 'ENERAL !PPROACH TO $IGITAL $OWNCONVERSION  )N DIGITAL DOWNCONVERSION   THE ANALOG )& SIGNAL IS FIRST SAMPLED BY AN !$#  AND ALL OF THE SUBSEQUENT PROCESSING IS THEN DONE DIGITALLY &IGURE  DEPICTS THE DIGITAL DOWNCONVERSION PROCESS FOR OUR PREVIOUS EXAMPLE  AGAIN IN THE FREQUENCY DOMAIN 4HE TOP LINE SCHEMATICALLY REPRE 
 When the organi- zation was fully developed, the number ofpeople in?olved inthe inter- pretation oftheradar information and inmaking useofitwas comparable tothenumber required toobtain it. Organization oftheHome Chain.—It has been mentioned inSec. 6..9 that theperformance ofCH stations depended very much onthenature oftheir sites. 
 Power Estimation. It is well known that for a gaussian process,43 using square-law signal detection, samples of the mean power P1. of the process are ex- ponentially distributed with variance P,2. 
 In Proceedings of the 2015 IEEE Joint Urban Remote Sensing Event (JURSE), Lausanne, Switzerland, 30 March–1 April 2015; pp. 1–4. 15. 
 7.1.3 The main lobe is at zero degrees. The first irregularity in this particular radiation  pattern is the vestigial lobe, or "shoulder," on the side of the main beam. The vestigial lobe  does not always appear in antenna radiation patterns. 
 ORDER CORRECTION TO CANCEL THE QUADRATIC  TERM BT  WHICH COULD BE OBTAINED IF  $ WERE ALSO TIME 
 The SNR is about 18 dB in the experiment. All the sub-images are stitched together based on the affine transformation algorithms [ 9]. In Figure 8a, the image in the conventional FFT-based algorithm suffers from blur. 
 CIES AND THE RESULTING DOPPLER SPECTRA PLOTTED IN A NESTED DISPLAY 4HE TWO COLUMNS OF PLOTS SHOW RECEIVED POWER VERSUS DOPPLER FREQUENCY FOR THE  EIGHT OPERATING FREQUENCIES AS LABELED  AND FOR THE TARGET APPROACHING RIGHT COL 
   WHEN THE REFERENCE CELLS ARE INDEPENDENT AND IDENTICALLY DISTRIBUTED 4HE SECOND  THRESHOLD IS ADAPTIVE AND MAINTAINS A LOW  0FA WHEN THE REFERENCE SAMPLES ARE COR 
 WAVES -ANY (& /4( RADARS UTILIZE AN &- 
 Boulder. Colorado. NOAATechnical ReportERL283-WPL 26.July,1973. 
 The nodding-beam height finder is one of the oldest techniques for measuring the eleva-  tion angle of aircraft targets. It is also one of the best. Its accuracy is probably as good or better  than any other technique. 
 393–397, May 1980. 38. H. 
 29, no. 2, pp. 284–302, April 2004. 
    IS THE CLUTTER MAP AMPLITUDE FROM THE PREVIOUS SCAN   YI  IS THE UPDATED  CLUTTER MAP AMPLITUDE   XI  IS THE RADAR OUTPUT ON THE PRESENT SCAN  AND THE CONSTANT   @  DETERMINES THE MEMORY OF THE RECURSIVE FILTER 4HE TEST FOR DETECTING A TARGET BASED  ON THE OUTPUT XI  IS   XI K YI4    q 
 1.4 RADAR FREQUENCIES  Conventional radars generally have been operated at frequencies extending from about  220 MHz to 35 GHz, a spread of more than seven octaves. These are not necessarily the Jimits,  since radars can be, and have been, operated at frequencies outside either end of this range.  Skywave HF over-the-horizon (0TH) radar might be at frequencies as low as 4 or 5 MHz, and  groundwave HF radars as low as 2 MHz. 
 It can be seen that the sidelobes of the three point targets are asymmetrical because the IMAM method only deals with the spatial variance of the Doppler rate. The peak sidelobe ratios are about −10 dB, as shown in Table 4. Figures 9d and 10d show the results of the EMAM method. 
 The FM -bandwidth B and the duration  τ of the FM signal determine the compression.  With SAR the duration is:     € τ=T  (10.24)  B from Equation (9.19):  € Δfmax=B=2v2T λR0sin2θ0 (.25)  The linear FM rate b arises from this as:   € b=B2π T=4πv2 λR0sin2θ0 (10.26)      . Radar System Engineering  Chapter 9 – Synthetic Aperture Radar  83     The time function of the received signal has the following phase:   € ϕ(t)=ω0t−ϕ0+4π λvtcosθ0−2πv2t2 λR0sin2θ0 ⇓⇓ ⇓ ⇓ =2πf0t−4πR0 λ+2πfdtcosθ0−1 2bt2 (10.27)(10.28)            The amplitude is:     € x(t)=cosϕ(t) (10.29)  If the signal passes through a matched filter, meaning a filter, which has the opposite fre- quency characterist ic as the received frequency, the result is the function:     € g(t)=const ⋅cos(ω0+ωd 2)t⋅sin(1 24πv2T λR0tsin2θ0) 1 24πv2T λR0tsin2θ0 (10.30)  Here the matched filter has been tuned to  € f0+fd. 
 The basic power-generating unit comes in a relatively small  size; hence, many units have to be combined in some manner to achieve the power levels  required for radar. The higher the frequency, the less the power available from an individual  solid-state device and the more difficult will be the combining problem because of the larger  number of devices required. At the lower microwave frequencies, the transistor is one of the  better available solid-state sources. 
 Gallop, M. A., Jr., and L. E. 
 TIMES REQUIRED  ESPECIALLY FOR LARGER REFLECTORS 4HESE CONSIDERATIONS AND CONSTRAINTS DRIVE THE CHOICES OF MATERIALS  STRUCTURAL DESIGNS  PASSIVE AND ACTIVE MECHANISMS  ETC )T IS BEYOND THE SCOPE OF THIS CHAPTER TO ADDRESS THIS TOPIC IN DETAIL (OWEVER  ITS USEFUL TO SHOW A COUPLE EXAMPLES FOR ILLUSTRATION #ONSIDER  FIRST  A GROUND 
 Radars will be used to make atmospheric and geological observations. Two of the radars proposed are the tropical-rain mapping radar (TRAMAR) and the land, ocean, and rain radar altimeter (LORRA).67 Global Air Traffic Surveillance.12 ATC is increasingly a matter of global concern, and the explosive growth of aircraft density in, around, and between major metropolitan areas in Europe and North America is common knowledge. If a United Nations organization were responsible for ATC for 120 to 130 nations in the world, it is conceivable that as many as 84,000 commercial aircraft could require ATC in the twenty-first century. 
 Hayes, and L. C. Bomar: mm-wave Reflectivity of Land and Sea, M~crowu~lr J . 
 pub!.).  72. Blomfield, D. 
 D. J. Mudgway, Big Dish: Building America's Deep Space Connection to the Planets ,  Gainesville: University of Florida Press, 2005. 
 Interference may be manifested not only as an infrequent  problem, but may be an issue of multiple signals contending  for the same spectrum , either intentionally or unintentionally.  Discovering such overlapping signals can be ve ry difficult  using traditional test equipment.    Figure 9. 
 (/2):/. 2!$!2   Óä°ÇÇ   # 'OUTELARD  h4HE ./342!$!-53 PROJECT &RENCH /4( 
 Schwartz, M.: A Coincidence Procedure for Signal Detection, IRE Trans., vol. IT-2, pp. 135-139,  December, J 956. 
 ( a) Sub-image of ship04; ( b) Refocused image with DCT method; ( c) Refocused image with PGA method; ( d) Refocused image with proposed method.   (a) (b)  Figure 13. The entropies and IC values convergence of two sub-images versus the number of iterations. 
 The scan modulation would be effectively sup  pressed in the output of the receiver, and the output would be used to measure range in the  normal manner. In this case, the error signal can be recovered from the AGC voltage since it  varies at the conical-scan frequency. The AGC voltage will also contain any amplitude fluctua-  tions that appear with the echo signal. 
 Sensors 2019 ,19, 1649 cheap SAR systems and UAV and drones, the problem of high cost of the system has pushed research to ﬁnd new solutions in the development of such systems that imply in some cases the development of new techniques trying to focus the acquired raw data matrix using a subset of the ancillary data parameters and in presence of strong geometry anomalies that occur in such cases [ 13–18]. As the availability of the required parameters has always been guaranteed, at our knowledge, none has been done to develop algorithms able to estimate the reference function to be used as the focusing operator from the data itself and develop a completely blind focusing procedure. While all the available algorithms to solve the SAR data-focusing problem are model driven, as they use ancillary parameters information to model the inverse problem in radar soil backscatter, in this paper a data-driven approach to develop a totally blind SAR data-focusing, based on the use of the Singular Values Decomposition (SVD) and LMS ﬁtting of the phase information extracted from singular vectors is presented, able to obtain good image quality working on the complex SAR raw data matrix in absence of any information about the sensor. 
 Taylor, T. T.: Design of Line•source Antennas for Narrow Bcamwidth and Low Side 1.ohcs, I RE  Trans., vol. AP-3, pp. 
 54-61. February, 1977.  36. 
 Accuracy Evaluation According to [ 25], the ﬁtting accuracy of a deformation model can be reﬂected by the HP-deformation component. The smaller the HP-deformation is, the higher the accuracy of the selected model. The HP-deformation of each interferogram obtained through the rheological model was compared with that of the linear velocity model. 
 Gautier, H., and P. Tournois: Signal Processing Using Surface-Acoustic-Wave and Digital Components, IEE Proc., vol. 127, pt. 
 SCATTERED SKYWAVE RADAR ECHOES v  0ROC )NT  2ADAR #ONF  4OULOUSE  /CTOBER   3 * !NDERSON  h4ARGET CLASSIFICATION  RECOGNITION AND IDENTIFICATION WITH (& RADAR  PROC .!4/  2ESEARCH AND 4ECHNOLOGY !GENCY v  3ENSORS AND %LECTRONICS 4ECHNOLOGY 0ANEL 3YMPOSIUM  3%4 
 TO 
 The optical components are telescopic, and the powers of the elements in two perpendicular planes are unequal. The telescopic elements in- clude both spherical and cylindrical elements. The evolution of this processor is based in part upon the recognition that sig- nal histories may be assigned focal lengths and behave to some degree as optical elements. 
 MENTS OF LESS THAN THREE DIMENSIONS 4HE EXTENDEDDUAL COORDINATE SYSTEM +ALMAN FILTER PREVENTS PSEUDO 
 IfA@istheangle turned bythemount,. 194 THE GATHERING AND PRESENTA TIQN OF h=DsinA+. But D’=R’–h’,sothat h=(1?Tn2A;4)%”RADAR DATA [SEC. 
 Eng. Geol. 2016 ,209, 175–186. 
 In other experiments with the PPI, the integration improvement has been reported to be  proportional to 1.5 dB per doubling of the number of pulses, which corresponds to n112• so  Improvements as high as 1.8 dB per doubling were also observed, but this is less than the 2.2 to . DETECTION OF RADAR SIGNALS IN NOISE 387  12  ~ 11 A  ~ 0 10 0  l.()  I... 9 2 8 ... 
 In another nearby pixel, even if the terrain is nominally the same as in the  first pixel, the coherent returns will add differently and the pixel magnitude will be  somewhat different. This phenomenon, characteristic of coherent imagery, causes  SAR imagery of terrain to exhibit more pixel-to-pixel fluctuation (speckle) than cor - responding optical imagery. Stimson5 points out, “Sometimes the beam of the real antenna may be wide enough  to enable the same area to be mapped several times without changing the antenna’s  look angle. 
 451–459, July 1980. 65. D. 
 The blockhg oscillator can beused asa“scaling” orcounting-down circuit foracontinuous pulse train ofdefinite frequency bymaking the natural period slightly longer than theexpected one and applying signals oftheproper height asshown inthebottom diagram ofFig. 13”19. The counting ratio isdependable only uptoavalue of5or10but synchroni- zation occurs tomany times this value. 
 ultofthedopplcr ~hift, e:ich target gives t~vo output frequencies, and sotwo range indirati[ons The >eriom+nes (Ifthis depends onthe ratio ofthe doppler frequenrl- tomean beat frequency,. SEC. 5.10] ALTERNATIVE F-M RANGING SYSTEM 149 This ratio depends ontarget speed, wavelength, repetition rate, and range accuracy, and might conceivably have almost any value. 
 IRE, vol. 27, pp. 317-328, October, 1963. 
 Inmountainous temati, this problem isvery serious. Anarrangement that gives signals only from targets that aremoving appears tobethebest solution tothepermanent- echo problem. Afact that has been too little recognized when radar systems are discussed isthat the organization which istomake useofthepositional. 
 Aspect entropy is calculated using the RCS curve as 253. Sensors 2019 ,19, 346 mentioned above. In subsection A, the RCS curve is associated with the pixel. 
 5. PRFs high enough so that all targets with radial velocities below 40 knots can be  censored 6. Sensitivity velocity control (SVC), which censors radially slow, small targets,  while accepting radially fast targets and large targets Combinations of techniques 1 through 4 are used in most air-traffic-control radars  where the smallest targets of interest have an RCS of one-square meter or greater. 
 SEC. 78] TELERAN 241 weather and route information, can provide allofthe data needed by aircraft foren-route navigation and forairport approach. Further, high- precision ground radar cansupply alltheinformation that apilot requires, inaddition tohisown flight instruments, forinstrument approach and landing. 
 Target echo energy cross-polar - ized to the radar antenna causes crosstalk (cross coupling) in radars; i.e., the azimuth  error causes output from the elevation-error detector, and the elevation error causes  output from the azimuth-error detector. Generally, this effect is negligible because the  cross-polarized energy is usually a small fraction of the received polarization from  typical targets, and it is normally reduced by about 20 dB by the antenna design.  However, in special cases, the resultant crosstalk can be very high and may cause a  large tracking error and possible loss of track. 
 9.11  Adaptive Arrays   .................................................  9.14  9.7 Transmitter-Related ECCM  ....................................  9.16 9.8 Receiver-Related ECCM  ........................................ 
 The other technique, density taper, is applicable to the design of either linear arrays or to  large planar arrays. Consider a uniform grid of possible element locations with~qual spacing.  The aperture illumination function that would normally be considered for a conventional  antenna is used as the model for determining the density of equal-amplitude elements. 
 For this reason the first grid is also known as the shadow  qrid. The purpose of the shadow grid is to suppress electron emission from those portions of  the cathode which otherwise would be intercepted by the second, or control, grid. The cathode  surface under each opening of the first grid is dimpled. 
 WAVELENGTH RADAR HAIL DETECTOR v  * !PPL -ETEOROL   VOL     PP n    2 % #ARBONE  $ !TLAS  0 %CCLES  2 &ETTER  AND % -UELLER  h$UAL WAVELENGTH RADAR HAIL   DETECTION v "ULL !MER -ETEOR 3OC  VOL   PP n    4 /GUCHI  h%LECTROMAGNETIC WAVE PROPAGATION AND SCATTERING IN RAIN AND OTHER HYDROMETEORS v  0ROC )%%%  VOL   PP n    2 * $ONALDSON  *R  h4HE MEASUREMENT OF CLOUD LIQUID 
 The  sum and difference signals appear at the two other arms of the hybrid. On reception,  the outputs of the sum arm and the difference arm are each heterodyned to an intermediate  frequency and amplified as,in any superheterodyne receiver. The transmitter is connected to  thesum arm. 
 Therefore, any measured profile would not be representative of the average  evaporation ducting conditions, the conditions that an assessment system must consider. Elevated Ducts.  If meteorological conditions cause a trapping layer to occur  aloft, such that the base of the duct occurs above the Earth’s surface, the duct is  referred to as an elevated duct, as illustrated in Figure 26.7. 
 which is a measure of the amount of fluctuation in  the cross section, is found to be independent of the magnitude of the radar cross section but is  a function of the physical size of the bird relative to the radar wavelength.91 Thus measure­ ments of the mean-to-median ratio might be used to determine the size or the bird b':'ing  observed. The fluctuations in the radar cross section have been attributed to the relative  motions between the various parts of the bird and to changes in aspect, as well as to the  wing-beat frequency. For example, spectral measurements of a small nocturnal migrant (a  pipit) showed a wing-beat frequency of J 5.8 Hz; and a migrating rapit (a honey buzzard) gave  a rrcqucncy or 3.2 Hz.92 J\ mallard produced a frequency of 6.5 Hz, plus harmonics at 13 and  N  E u  ~ u  QJ  V,  "' "' e u  0 u 0 er 100 -·---•--,-r--·-~----------~ 90 . 
 G., and R. F. Broderick: Spaceborne-Radar Applications, chap. 
 LENGTH  DETERMINED THE WIDTH OF THE ILLUMINATED SWATH ON THE SURFACE 4HIS PROVIDED AN  UPPER BOUND ON THE IMAGED SWATH WIDTH  WHICH  IN THE CASE OF  -AGELLAN  WAS LESS THAN  THE SWATH ACTUALLY ILLUMINATED 4HE IMAGED SWATH WIDTH WAS CHOSEN TO BE SOMEWHAT WIDER THAN THE ORBIT 
 A better technique for medium PRF is to use seven or eight PRFs which cover nearly an octave in frequency and to require detections in at least three of these to declare a target report. The advantage is that doppler visibility is better than with the major-minor approach, and hence better range performance in sidelobe clutter is achieved (where some PRFs may be obscured by clutter). However, it is more susceptible to ghosting owing to the high doppler visibility. 
 W. K. Rivers, “Low-angle radar sea return at 3-mm wavelength,” Final Tech. 
 The use of high-range-resolution radar for  profiling a target, and the inverse synthetic aperture radar mentioned above are two practical  exam pies of target classification methods that might be called approximations of inverse  scattering.  Instead of examining the radar echo as a function of frequency, the target response to an  impulse can give the equivalent information since the Fourier transform of the impulse con­ tains all frequencies. (In the above, an impulse is an infinitesimally short pulse, and the target  response is the echo signal as a function of time.) This has been proposed as a means of target  classification,52 with the impulse being approximated by a short microwave pulse. 
 Dionne, G. F.: A Review of Ferrites for Microwave Application, Proc. IEEE, vol. 
 HORIZON RADARS 4HE USE OF %##- TECHNIQUES IN OTHER TYPES OF RADARS SUCH AS MORTAR LOCATION RADARS  MISSILE GUIDANCE RADARS  AND NAVIGATION RADARS IS CONSIDERED IN THE LITERATURE  3URVEILLANCE 2ADARS  4HE FUNCTION OF A SURVEILLANCE RADAR IS TO SEARCH A LARGE  VOLUME OF SPACE AND LOCATE THE POSITION OF TARGETS WITHIN THE SEARCH COVERAGE 4HE RADAR RANGE AND THE AZIMUTH 
 Relationship between altitude and total electron content (TEC) as well as Bcosθ. The ﬁrst mean value theorem for deﬁnite integrals shows that /angbracketleftBcosθ/angbracketrightTEC is actually the area of the region under the “Bcos θvs. TEC” curve of Figure 3c. 
 (a)( b) (c)( d) Figure 13. The simulation results of extended target. ( a) Original SAR image. 
 VIEWING ALTIMETER IS PROPORTIONAL TO THE RADARS RANGE RESOLUTION AND INVERSELY PROPORTIONAL TO THE SQUARE ROOT OF THE NUMBER OF STATISTICALLY INDEPENDENT MEASUREMENTS LOOKS  COMBINED FOR EACH DATA POINT /CEAN 
 B. Walsh, “An eagle in the sky,” Countermeasures—The Military Electron. Mag ., pp. 
 M. Hall and W. W. 
 “Totally independent bistatic radar receiver with real- time microprocessor scan correction,” IEEE Int. Radar Conf ., 1980, pp. 380–386. 
 POINT DIGITAL PROCESSING 4HE REFLECTIVITY  MEAN DOPPLER VELOCITY  AND SPECTRUM WIDTH CAN ALL BE ESTIMATED DIGITALLY FROM THE FLOATING 
 (13.8) for the detection  of targets in clutter. (As will be discussed in Sec. 13.4 there are techniques for receiver  detector-design that can avoid ~uch of this loss.) A corollary consequence of high resolution  is a change in the probability density function of the sea echo, as described next. 
 They are able to register quite  respectable performances, therefore, simply because a thin layer attached to a  metallic surface need not be very heavy. In this respect, the surface traveling-wave  contribution due to long, smooth surfaces is one of the easiest to suppress. Even  so, the thickness and geometric distribution of surface-wave absorbers should be  varied for optimum performance. 
 The light from the initial flash excites the second layer, emitting a  persistent luminescence. The tandem action of the cascade screen results in greater efficiency  than if the second, long-persistence layer had been excited by the electron beam directly,  instead of by light emitted from the first layer. In the P14 screen, the initial flash of short  duration from the first screen is blue in color and the persistent light radiated by the second  screen is orange. 
 The  peak errors are severe and can be many times the angular separation between the target and its  Antenna beam  path -----~:~:~ Image  Figure S.15 Low-angle tracking illustrating the surface-reflected signal path and the target image. 2.0  1.8  1.6  1.4  1.2 :  QB  "' 0.6  IA.I  uJ a: 0.4  "' uJ  0 0.2 ' a: 0 a: Q a:  "" z -0.2 0  ~ ;,--0.4 ..,  ..J  "" -0.6  -a.a  ·!.O  -1.2  .::1.4  -1.6  -1.8  -2.0  TRACK TIME (MINUTES)  Figure 5.16 Example of the measured elevation tracking error using a phased-array radar with 2._7~-beam width. Aircraft target flew out in range  at a nearly constant altitude. 
 Lord Rayleigh investigated the scattering of light  by precipitation  in 1870.  The results apply in the same manner for Radar technology.  In the Rayleigh region  the Radar backscattering cross- section, normalized by the geometric cross -sectional area, is  proportional to r4 and consequently squarely proport ional to the cross -sectional area:  10-110010110210-310-210-1100101   σ πr2=92πr λ0        4  σ πr2=1Rayleigh region Mie orResonanceregionoptical region circumference in wave lengths 2πr/λ  σsphere /πr2. 
 T. Lebenbaum: Letter in Microwave J., vol. 2, pp. 
 H.: Design of Radiating ~lements for Large Planar Arrays: ~ccom~lishthents and Re-  maining Challenges, Micro,\+ul.e J., vol. 15, pp. 27-34, September, 1972. 
 The AGC performance in conical-scan radars provides a similar constant angle error sensitivity. One major limitation in conical-scan radars is that the AGC bandwidth must be sufficiently lower than the scan frequency to prevent the AGC from removing the modulation containing the angle error information. The very low SNR effects on conical scan differ from the effects on monopulse, as discussed in detail in Ref. 
 Finally, the front-end spurious characteristic affects the susceptibility of off-frequency interference. Coherent radar performance is even more affected by spurious mixer charac- teristics. Range and velocity accuracy is degraded in the pulse doppler radar; stationary-target cancellation is impaired in MTI (moving-target indication) radar; and range sidelobes are raised in high-resolution pulse compression systems. 
 The echo froni forests differs depending on the season. By contrast. sea  eclio is more uniform over tlie oceans of tlie world, providing the wind conditions are the  same. 
 Four characteristics ofmagnetrons arelargely responsible forthese troubles. Change ofFrequency withCurrent.—The input impedance ofamag- netron varies with voltage asshown inFig. 10.29. 
 Thed-chigh-voltage canbeappliedbeforetheRFsignalifthedesignissuchthatvoltage breakdown orarcingdoesnotoccur,.Thisleadstothepossibility ofmodulating thetube withouttheneedforahigh-power modulator asrequired withcathode pulsing.Suchopera­ tionispossiblewiththeforward-wave CFAusingacoldsecondary-emission cathode. Thed-c operating voltage isapplied continuously between cathode andanode.Thetuberemains inactive untiltheapplication oftheRFinputpulsestartstheemission process, causing amplification totakeplace.AttheendoftheRFdrive-pulse theelectrons remaining inthe tubemustbeclearedfromtheinteraction areatoavoidfeedback whichgenerates oscillations ornoise.Inreentrant CFAs,theelectron streamcanbecollected aftertheremovaloftheRF. RADAR TRANSMITTERS 21 1  drive-pulse by mounting at1 electrode in tlie cathode, but insulated from it, in the region of the  drift space between the RF input and output ports. 
 The folded-tape meander line20 is the UHF or microwave analog of the low- frequency, all-pass network. A meander line consists of a thin conducting tape extending back and forth midway between two ground planes. The space be- tween tape meanders and between the tape and the ground plane is filled with dielectric material. 
 6 
 SION PATH STATISTICAL CLIMATOLOGIES AND FORECASTS ARE NECESSARY FOR RADAR DESIGN AND FOR DEVELOPMENT OF SITE 
 13.53), alinear potentiometer turned byamechanical repeater provides the azimuth data, adifferential gear allowing control ofthe sector displayed. The vertical deflection isobtained byadding, inthedriving amplifiers, aslowly varying voltage proportional tothe azimuth angle measured from theedge ofthesector chosen and arange sweep modulated. 548 THERECEIVING SYSTEM—INDICATORS [SEC. 
 7IDTH-(Z 4OTAL0ULSES  IN 4 /4 2ANGE 
 D" INCREASE BECAUSE BOTH SIDEBANDS OF NOISE AFFECT CLUT 
 J., vol. 18,  pp. 222-234. 
 The method of inverse scattering seems to require an examination of the target over a  large frequency range, perhaps as much as 10 to 1. If the phase shift as well as the amplitude of  the echo are measured, fewer frequencies might be utilized than when amplitude alone is  obtained.s6 Experiments with as many as 12 frequencies have been carried out for simple  scattering objects, but as few as four frequencies were said to be adequate for the discrimina­ tion of objects as complex as aircraft. SJ  Automatic target classification. 
 V  
 MENT TO BE MATCHED IN ITS OPERATING ENVIRONMENT THE SELF 
 Infrequency modulation, onthe other hand, the carrier operates ataconstant power level. Nosuch advantages exist foramplitude modulation inconnection with c-w synchronization methods. Low-level, more orless cent inuous interference can bevery disturbing, and thenatural suppressing effect of the limiter and discriminator inanf-m receiver can beofvery great advantage. 
 &ED 3ERIES &EED  !N END 
 ¯  WHERE  QX     SPATIAL AUTOCORRELATION FUNCTION OF SURFACE HEIGHTS  P   ANGLE WITH VERTICAL  RH   STANDARD DEVIATION OF SURFACE HEIGHTS  K   OK  *   FIRST 
 Also  shown in Fig. 7.3 is the radiation pattern for the cosine aperture distribution.  71 z a A(z) = cos - 111 < 2 a  -4rr -3rr -27l -7l 0 7r 27 3n 47  T(Q/A) sin 4  Figure 7.3 The solid curve is the antenna radiation pattern produced by a uniform aperturedistribution;  the dashed curve represents the antenna radiation pattern of an aperture distribution proportional to the  cosine function. 
 Cohen, A., and A. Smolski: The Effect of Rain on Satellite Communications Earth Terminal Rigid  Radomcs. J\ticrm1·ar·c J., vol. 
 TO 
 TORS CAN EASILY SEE   4HE BASIC NOTION OF DOPPLER  RESONANCES  STEPPED 3&7-   AND MULTIFREQUENCY  -&2  SIGNATURES IS MODULATION EITHER BY REFLECTIONS FROM MOVING PARTS  EG  ENGINE COMPRESSOR  TURBINE  ROTOR  OR PROPELLER BLADES  OR BY INTERACTIONS FROM SCATTERERS ALONG THE AIRCRAFT OR VEHICLE  EG  FUSELAGE  WING  ANTENNAS  OR STORES 3&7--&2 SIGNA 
 Sinclair, G.: Theory of Models of Electromagnetic Systems, Proc. IRE, vol. 36, pp. 
 &XEJX SP  7HEN THE BEAM IS SCANNED TO  P  THE QUANTIZATION LOBES OCCUR AT AN ANGLE  P   WHERE  SIN SINPP oSL  4HE GAIN OF THE APERTURE VARIES AS COS  P  AND THE RELATIVE AMPLITUDE OF THE QUANTI 
 3.136). However, Rubin9 describes a four-stage successive detection design having a bandwidth of 640 MHz centered at 800 MHz. Pulse response time of 2.5 ns is claimed. 
 This reasoning can be easily generalized to other sources of errors like inaccuracy in the antennas placement, deformation of the system geometry, etc. The discussed behavior in the MIMO SideLobe Level has already been noticed in various experimental tests with MIMO arrays [ 14,15]. 2.2. 
 TRACK COMPONENT OF THE MEAN SURFACE GRADIENT #OURTESY OF %UROPEAN 3PACE !GENCY  . £n°{{  2!$!2 (!.$"//+  4HE CAPSULES TRAJECTORY WAS ESTIMATED BY DOPPLER RADIO READINGS AND AERODYNAMIC  CALCULATIONS  AND BY SUBTRACTING THIS FROM THE ABSOLUTE RADAR ALTITUDE READINGS  A GROUND PROFILE COULD BE MEASURED 2EADINGS SPAN A VERTICAL RANGE OF  KM DOWN TO  KM  DURING WHICH TIME THE CAPSULE DRIFTED HORIZONTALLY FOR A DISTANCE OF ABOUT  KM !NALYSIS OF THE RETURN PULSES YIELDED ESTIMATES OF ELEVATION VARIATIONS OF THE OVER 
 DARD  WITH REQUIREMENTS FOR NATIONALLY ISSUED CERTIFICATES OF TYPE APPROVAL 4HE NEED TO INCLUDE THE USE OF RADAR WITHIN THE )NTERNATIONAL #OLLISION 2EGULATIONS WAS CLEARLY SEEN  TOGETHER WITH THE NEED FOR CERTIFICATION OF USERS &)'52%  $UAL 
 TRACKING LOOP GAINS CONSTANT FOR STABLE AUTOMATIC ANGLE TRACKING &IGURE  IS A BLOCK DIAGRAM OF TYPICAL MONOPULSE RADARS 4HE  SUM SIGNAL  ELEVA 
 Boxcar generator. When extracting the modulation imposed on a repetitive train of narrow  pulses, it is usually convenient to stretch the pulses before low-pass filtering. This is called  boxcaring, or sample and hold. 
 TARGET 
 13.29. When S,asingle clamp ofproper polarity, isclosed, anequilibrium state isreached inwhich Xdiffers from ground potential !E R l----mx (Js c Rg .(1)Clym;;,g >T -+1 r+oli+on. (2)Vxwhen RC=T (3)V&:~--------—-==--—-.- ifi::--Gnd T--——_____________----E FIG.13.29.—Basic sawtooth generator. 
 A.: unpublished manuscript referred to by H. A. Wheeler (see Ref. 
 For certain tasks, novery high information rate isrequired, and for such applications the various c-w methods (Chap. 5)deserve considera- tion. Intheproblem oftheradio altimeter, forexample, what isrequired ismerely therange ofasingle, large, ever-present target—the earth below. 
 The mean velocity ( v) is given by the first moment of the spectrum:  vvSv dv S vdv=∫ ∫( ) ( ) (19.34) The spectrum (velocity) width ( sv) is given by taking the square root of the second  central moment:  σvv v S vdv S vdv22 =−∫ ∫( ) ( ) ( ) (19.35) Radar meteorologists sometimes refer to σv2 as the spectrum variance because of  its computational equivalence to the variance of a continuously distributed random  variable. In short, S(v) is analogous to a probability density function for v since it is  actually a reflectivity weighted distribution of particle velocities within the scattering  volume. The term spectrum width  will be used to refer to sv. 
 24,Chap. 8. For example, itmight bearranged topresent asignal atagiven point ontheoscilloscope sweep about half thetime, theobserver being required tojudge whether ornot thesignal was there. 
 An  experimental model at C band had a combined mismatch and insertion loss of about 0.8 dB.  The dome might also be fabricated from radome-like material using a honeycomb skin with  lightweight printed-circuit phase shifts glued to the inner surface.  In a conventional phased array, a linear phase gradient is applied across the aperture t.o  steer the beam. 
 Figure 1.4 - Direct and indirect waves. 6Figure 1.5 - Vertical-plane coverage diagram (3050 MHz, antenna height 125 feet, wave height 4 feet). 7Figure 1.6 - Vertical-plane coverage diagram (1000 MHz, vertical beam width 10˚, antenna height 80 feet, wave height 0 feet). 
 ) " $ *% )*$   
 Chernikov, “Spectra of radar signals from sea surface for different  polarizations,” Izv. Atmos. Oceanic. 
 Thusweneedonlyobtainthefrequency-response function thatmaximizes thesignal-to-noise ratioattheoutputoftheIF.TheIFamplifier maybeconsidered asafilterwithgain.The response ofthisfilterasafunction offrequency istheproperty ofinterest. Forareceived waveform s(t)withagivenratioofsignalenergyEtonoiseenergyNo(or noisepowerperhertzofbandwidth), North jshowedthatthefrequency-response function of thelinear,time-invariant filterwhich·maximizes theoutputpeak-signal-to-mean-noise (power) ratioforafixedinputsignal-to-noise (energy) ratiois H(J)=GaS*(J) exp(-j2nftd (10.1) 00 whereS(J)=fs(t)exp(-j2nJt)dt=voltage spectrum (Fourier transform) ofinput -00 signal S*(J)=complex conjugate ofS(J) tj=fixedvalueoftimeatwhichsignalisobserved tobemaximum Ga=constant equaltomaximum filtergain(generally takentobeunity) Thenoisethataccompanies thesignalisassumed tobestationary andtohaveauniform spectrum (whitenoise).Itneednotbegaussian.Ifthenoiseisnotwhite,Eq.(10.1)maybe modified asdiscussed laterinthissection. Thefilterwhosefrequency-response function is givenbyEq.(10.1)hasbeencalledtheNorthfilter,theconjugate filter,ormoreusuallythe matched filter.IthasalsobeencalledtheFouriertransJorm criterion. 
 Thedifference between thetwoantenna gainsisusuallysmall.The powergainandthedirective gainmayberelatedbytheradiation efficiency factorp,asfollows: G=p,GD (7.7) Theradiation efficiency isalsotheratioofthetotalpowerradiated bytheantenna tothenet poweraccepted bytheantenna atitsterminals. Thedifference between thetotalpower radiated andthenetpoweraccepted isthepowerdissipated withintheantenna. Theradiation efficiency isaninherent property ofanantenna andisnotdependent onsuchfactorsas impedance orpolarization match. 
 Another method foremploying frequency scaninaplanararrayistousethefrequency changetosteerinonecoordinate andphaseshifterstosteerintheother.68Thisissometimes calledarhase-freqrtellcr array(Fig.8.18)incontrast toaphase-phase arraywhichusesphase shifterstosteerinbothangular coordinates. Theantenna maybeconsidered asanumber of frequency-scan arraysplacedsidebyside.InanNbyMelement planararraytheremightbea separate snakefeedforeachoftheNrowstoobtainfrequency steering inonecoordinate, andi'onephaseshifterforeachoftheMcolumns toachievesteering intheorthogonal plane. Changing thefrequency ofasignalpropagating through alengthoftransmission lineis aconvenient method forobtaining aphaseshirt,butitisnotalwaysdesirable tooperate a radarwithachanging frequency. 
 (12.1 In) reduces to a particularly convenient relationship ifd and It are measured in statute  miles and feet, respectively.  I----- d (statute miles) = ,,, 211(ft) (12.1 1h)  or. f- d (nautical miles) = 1.23 m) (12.11~)  or. 
 The jamming power is seldom uniform over the band. Prelook  sampling of the environment can take place during the radar interpulse period just prior to  each transmission, so as to select on a pulse-to-pulse basis that frequency which offers the kast  jamming interference.51  Pulse compression is sometimes credited as causing the jammer to spread its energy over  a wider band than that of a normal spot jammer. However, pulse compression is seldom  deliberately employed as a prime ECCM technique. 
 80. W. Garrett, “Physicochemical effects of organic films at the sea surface and their role in the  interpretation of remotely sensed imagery,” in ONRL Workshop Proc.—Role of Surfactant Films  on the Interfacial Properties of the Sea Surface , F. 
 No attempt is made to reduce  the propagation velocity of the electromagnetic wave within this structure. The electron  beam is not close to the RF structure so it is not as limited in size as are the structures of  *  In electrical engineering, RF stands for radio frequency, but in radar, it is often used to mean the radar frequency. ch10.indd   3 12/17/07   2:19:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 It is then converted to baseband by mixing it with the rear signal in the balanced mixer (coherent detector). The doppler signal (now at baseband, with feedthrough at dc) is amplified in the video (doppler) amplifier, which has a bandwidth equal to the total range of possible doppler frequencies. It is then mixed with the speedgate LO, which is controlled by an AFC loop to keep the desired signal centered in the narrow speedgate (sometimes called the velocity gate or doppler tracker). 
 The noise figure Fn of a receiver is defined by the equation  i  N I: = ---- "-.. - tloise out of practical receiver -  " kTo BnG, noise out of ideal receiver at std temp To (2.40)  where No = rioise output from receiver, and G, = available gain. The standard temperature To  is taken to be 290 K, according to the Institute of Electrical and Electronics Engineers  definition. 
 H. Weil et al., “Scattering of electromagnetic waves by spheres,” University of Michigan, Radiat.  Lab. 
 cc 
  
 BORNE PLATFORM IN EXTENDING THE MAXIMUM DETECTION RANGE FOR AIR AND SURFACE TARGETS IS APPARENT WHEN ONE CONSIDERS THAT THE RADAR HORIZON IS  NMI FOR A  
 Table 17.1 lists typical applications 1^0 and requirements. This chapter will deal principally with airborne applications, although the basic principles can also be applied to the ground-based case. PRFs. 
 LOOP TRACKING $IVERSITY TECHNIQUES  WHICH CAN PROVIDE STATISTICALLY INDEPENDENT SAMPLES OF TARGET  SCINTILLATION  OFFER A MEANS FOR REDUCING TARGET SCINTILLATION EFFECTS 4HE MOST PRACTICAL TECHNIQUE IS FREQUENCY DIVERSITY USING PULSE 
 Condition 1restricts our attention totargets within the horizon. Condition 2bars, forthe present, consideration ofradar search atlow angles over water, although later weshall include this case byasuitable modification oftheradar equation. Microwave radar over land appears toberelatively free, even atlow angles, from thereflection effects which aresopronounced atlonger wavelengths. 
 But, as is true for most endeavors, the quality of the prediction is a function of  the amount of effort employed in determining the quantitative effects of the various pa-  rameters. Unfortunately, the effort required to specify completely the effects of all radar pa-  rameters to the degree of accuracy required for range prediction is usually not economically  justified. A compromise is always necessary between what one would like to have and what  one can actually get with reasonable effort. 
 Although themost usual pulser load isthemagnetron, theload prob- lem ingeneral will beconsidered briefly. The eventual load will differ from. apure resistance byhaving acertain amount ofcapacity and induct- ance associated with it,and itwill certainly benonlinear. 
 In the tropics we have found that  sudden changes in air-pressures, in humidity, and in  other meteorological conditions produce widely differing  results on radar apparatus. We therefore have to use  expert forecasts to know what effect the weather will  have on radar itself, and in turn we can use radar to find  out what sort of weather is to be expected in the immedi-  ate future! :  The radio-sonde (radio-transmitting weather balloon)  now has a useful colleague in the weather balloon fitted  with simple radar reflectors, the course and height of  which can be spotted in a few minutes by relatively  simpie ground radar apparatus. Rain-clouds can also  be plotted on some centimetric radar equipment, and,  indeed, greater accuracy of weather forecasting may  become one of radar’s valuable contributions to navi-  gation, a contribution as great as that given by radar in  more direct aids to marine and air transport. 
 The measurement of pulsed sources is intrinsi- cally much more difficult than the measurement of CW sources. The pulse struc- ture produces very substantial AM that inevitably conflicts in direct and indirect ways with any attempt to measure the FM. In fact, it is possible to measure FM only up to half the repetition frequency, and then only by the use of rather sharp filters placed immediately following the Q detector. 
 AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .416x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 and the dimensionless track filtering parameter gtrack. Figure 7.35 bounds this region  of applicability. When l and gtrack are small, then there is no need for any more than  simple nearest neighbor tracking, and indeed, most tracking systems still use this  approach. 
 .   4(% 02/0!'!4)/. &!#4/2  &0  ). 4(% 2!$!2 %15!4)/.   ÓÈ°££ TO BE ON THE LEEWARD SIDE OF LAND MASSES AND MAY OCCUR BOTH DURING THE DAY AND AT  NIGHT )N ADDITION  SURFACE 
 The long time is due to the large inductance or the solenoid and by th,~ fact that the  waveguide around which the solenoid is wrapped acts as a shorted turn. The resulting eddy  currents generated by the shorted turn limit the speed with which the magnetic field can be  changed. The shorted-turn effect may be minimized by a waveguide made of plastic which is  coated with a thin copper plating. 
 Brown, B. P.: Radar Height Finding. chap. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter. 15.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 Sea Clutter at High Grazing Angles. 
 &IX RECEIVER COUNTERS HIGH RATES OF SWEPT 
 B-scope with antenna rotating at2rpm. Effective antenna height is100 ft. Target isasingle B-24. 
 This is due to energy radiated from the feed which is not intercepted by the  reflector. The radiation pattern also has a pronounced lobe in the backward direction (180")  due to diffraction effects of the reflector and to direct leakage through the mesh reflector  surface.  -10 0 20 40 60 80 100 120 140 160 180  Degrees off axis 0  m u - -10- 5r t .-  V) t  0) t c -- -20 t 0 . 
 Such curves are  available," but are not necessary since only Figs. 2.7 and 2.8 are needed. Substituting  Eq. 
 J. Daniels,  “An assessment of the fundamental performance of GPR against buried land - mines,” presented at SPIE Detection and Remediation Technologies for Mines and Minelike  Targets XII, Orlando , FL, April 2007 25. G. 
 RESOLUTION CLUTTER MAP FOR EFFECTIVE FALSE  ALARM CONTROL !LTHOUGH  THESE CONCEPTS HAD BEEN EXPLORED MANY YEARS EARLIER USING THE 6ELOCITY )NDICATING #OHERENT )NTEGRATOR 6)#)   OR THE #OHERENT -EMORY &ILTER #-&   TO IMPLEMENT A  DOPPLER FILTER BANK  AND STORAGE TUBES OR MAGNETIC DRUM MEMORY  TO IMPLEMENT CLUT 
 AREPS is not limited to just radar applications, however. AREPS  together with APM and its other embedded propagation models can provide assess - ments for LF to EHF communications (ground and sky wave), strike and electronic  countermeasures, Electronic Support Measures (ESM) vulnerabilities, and many other  applications. AREPS and APM are products of the atmospheric propagation branch of  the Space and Naval Warfare Systems Center (SPAWARSYSCEN), San Diego. 
 When the blocking oscillator fires, itdelivers atrigger tothe system and also shock-excites a15-Me/see resonant circuit. The oscillations sosetup arepassed through thedelay line, and thereafter amplified and detected. The delayed signal isused asatrigger; itisapplied totheblocking oscil- lator, which then fires and starts anew cycle. 
 Low-latency also allows the use of Correlated  Alert/Confirm. Here, a Swerling  I target RCS fluctuation model is assumed. This implies that when the same RF car - rier frequency is used for Alert and Confirm, the target RCS will be relatively constant  between the two dwells,61 providing additional range enhancement in terms of the  cumulative probability of detection. 
 L: "Radar Applications," IEEE Press, New York, 1988. 3. Barton, D. 
 Practical limitations oncommutator diameter, voltage per bar, and operation ataltitude restrict the use ofdynamotors. For example, itisnever wise toattempt touse dynamotors with outputs above 1200 volts. Motor-alternators with voltage regulators are the most reliable conversion means. 
 M. I. Skolnik (ed.). 
 Beacon Al’C.-To hold thebeacon local oscillator atagiven absolute frequency, some r-freference standard must beprovided, since themag- netron involved isinthebeacon, distant from theradar. Atmicrowave frequencies the reference standard isaresonant cavity. With proper attention todetails such astemperature compensation and moisture sealing, production-line cavities can bedepended upon tomaintain a specified frequency to1or2parts in10,000. 
 A single AGC loop (not shown), required to cope with only the target signal variations, is used to normalize the angle error signals. Angle Tracking: Conical Scan to Monopulse. This subsection assumes that the reader is familiar with the conical-scan and monopulse angle-tracking concepts described in Chap. 
 ................................ ......................  9  Radar Resolution  ................................ 
 GE-27,   pp. 709–718, 1989. 129. 
 Figure 9.29 applies only for the portion  FIGURE   9.29  Angle fluctuation versus path length for different  tropospheres ( from Final Report: Instrumentation Radar AN/FPS-16  (XN-2) by RCA under contract Bu Aer NOas 55-869c ) ch09.indd   41 12/15/07   6:07:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 
 Each oftheend compartments contains thetransmitter components. SEC. 11.12] ILL US1’IiA TIVE EXA hlI’LES OF R-F IIEADS 431 ofoneoftheradars. 
 The relative importance of these two effects determines whether there is a net increase or  a net decrease in transmission. In unfavorable cases, even strongly reflecting meshes can lose  their reflecting properties almost completely.  Cassegrain antenna.'9-23 This is an adaptation to the microwave region of an optical technique  invented in the seventeenth century by William Cassegrain, a contemporary of Isaac Newton. 
 Thisresultsinlessimprovement factorforatwo-frequency MTIas compared withasingle-frequency MTI.Notealsothattheclutterdopplerspreadofaradar whichactually radiated acarrierfrequency !J.fwouldbelessthanthatofaradaratcarrier frequency.f~. bytheamount !J.rlf~.Thetwo-frequency MTImighthavetheblindspeedsofa. radar at the difference frequency but it has none of its other favorable clutter characteristics. 
 There are other causes of error between radar estimates of precipitation rates and rain gauge measurements that are  not addressed herein, such as the spatial and temporal distribution of rain. ch02.indd   46 12/20/07   1:44:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 54. Peeler. G. 
 KM SWATH  AND  
 The entropies and IC values of the original and refocused images are calculated for quantitative evaluation of the focusing. The performance of the proposed method is compared with the DCT, and PGA methods and the original images. The entropies of sub-images with different method processing are presented in Table 2. 
 15 to 17.) Since CW radar generates its required average power with minimal peak power and may have extremely great frequency diversity, it is less readily de- tectable by intercepting equipment. This is particularly true when the intercepting receiver depends on a pulse structure to produce either an audio or a visual in- dication. Police radars and certain low-level personnel detection radars have this element of surprise. 
 )43 2ADAR 0ERFORMANCE -ODEL  4HE .2, 
 2.3. Ionosphere This special issue includes also two works investigating the e ﬀects of the ionosphere onto SAR imaging from spaceborne platforms. In [11], the ionospheric scintillation is considered, being the main limiting factor of spaceborne P-band SAR imaging. 
 PHASE AND QUADRITURE )1  DATA IS COLLECTED AND SENT TO THE SIGNAL PROCESSORS 4HERE  THE DATA IS PROCESSED IN A MANNER DEFINED BY THE SENSOR MODE  AND THE SIGNAL PROCESSING RESULTS ARE RETURNED TO THE CLIENT THAT REQUESTED THEM 4HIS TYPICALLY RESULTS IN DATABASE UPDATES ANDOR NEW ANTENNA JOB REQUESTS FROM THE CLIENT .EW ACTIVITIES CAN BE ADDED AT ANY TIME USING THIS MODULAR APPROACH !LTHOUGH THIS STRUCTURE IS COMPLEX AND THE SOFTWARE ENCOMPASSES MILLIONS OF LINES  OF CODE  MODERN -&!2 SOFTWARE INTEGRITY CAN BE MAINTAINED WITH STRICT CONTROL OF INTERFACES  FORMAL CONFIGURATION MANAGEMENT PROCESSES  AND FORMAL VERIFICATION AND VALIDATION SOFTWARE TOOLS )N ADDITION  MOST SUBPROGRAMS ARE DRIVEN BY READ 
   !. ).42/$5#4)/. !.$ /6%26)%7 /& 2!$!2   £°Ó£ ALSO AN EXAMPLE OF A RADAR !N EXCELLENT MEASURE OF THE SUCCESS  OF RADAR FOR MILITARY  AIR DEFENSE IS THE LARGE AMOUNTS OF MONEY THAT HAVE BEEN SPENT ON METHODS TO COUNTER  ITS EFFECTIVENESS 4HESE INCLUDE ELECTRONIC COUNTERMEASURES AND OTHER ASPECTS OF ELEC 
 One of the most popular methods is random crop. It can signiﬁcantly increase the amount of data. Recently, researchers usually use some ﬁxed frame to do random crop. 
 Details of these subsystems are found in Ref. 12. The radar parameters are shown in Table 22.9. 
 VEILLANCE IF A LAUNCH WERE BELIEVED TO BE IMMINENT  OR ELSE THE MISSILE MIGHT ESCAPE FROM THE RADAR FOOTPRINT WITHOUT BEING DETECTED !SSUME A #)4 OF  SECONDS AND A TOLERABLE REVISIT INTERVAL OF  S 4ASKS  AND  COULD BE INTERLEAVED  FOR EXAMPLE  BY CARRYING OUT FIVE DWELLS OF 4ASK   AND THEN ONE OF 4ASK   AND THEN REPEATING THIS PAT 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 5.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 Although an MFAR contains a very stable time reference, uncertainties in the rate  of change of terrain height, refraction, winds aloft, and very long coherent integration  times force the measurement of the clutter doppler error versus predicted frequency to  maintain proper focus and bin registration, as shown in the upper right in Figure 5.33. 
 CALLY SCANNED WITH THE MECHANICAL BORESITE PROVIDED AS AN INPUT TO THE RADAR  AND   MECHANICALLY SCANNED WITH ADDITIONAL ELECTRONIC SCANNING WITHIN AN OPERATOR 
 A high range resolution profile can be used to recognize a ship just as with an  aircraft.72 It naturally has the same weakness previously mentioned, and the aspect  or attitude must be known. If the attitude is known, then the major scatterers can be  mapped into a range profile and correlated with the ship power return in each cell. An  example of a ship range profile is shown in Figure 5.28. 
 In radar coordinates, the track of a target on a straight-line trajectory is curvilinear  and can generate apparent accelerations. This does not happen when tracking in rectilint.:ar  coordinates. The rectilinear coordinates of the updated target prediction are converted back to  radar coordinates to drive the antenna. 
 In one the scattering angle P (defined in Fig. 14.12) is exactly  ccjt~al to 180". In the otlicr, /I can take any value except 180". 
 The reflection cavity has an advantage in that a sizable portion of the carrier power is absorbed if the transmitter is kept tuned to the frequency of the cavity. This eliminates much of the saturation problem. A particularly attractive arrangement was proposed by Marsh and Wiltshire12 (Fig. 
 (Notethepotentially confusing nomenclature. Acascadeconfiguration ofthreedelaylines,eachcon,nected asasinglecanceler, iscalled atriplecanceler, butwhenconnected asatransversal filteritiscalledafour~pulse canceler.) Theweightsforatransversal filterwithndelaylinesthatgivesaresponse sin"nf"Tarethe coefficients oftheexpansion of(1-xY'.whicharethebi~omial coefficients withalternating sIgns: ( }1-1 n! Wj=-1(n-i+l}!(i-l)!'i=1,2,...,n+1 (4.10) Input Summer OutputFigure4.11General formofatrans­ versal(ornonrecursive) filterforMTI signalprocessing.. MTI AND PUL23E.DOPPLER RADAR 111  Tlie transversal filter with alterriating binomial weights is closely related to the filter  which maximizes the average of the ratio I, = (S/C),,,/(S/C)i,, where (SIC),,, is the signal-to-  clutter ratio at the output of the filter, and (S/C)i, is the signal-to-clutter ratio at the inp~t.~.~  Tlie average is taken over the range of doppler frequencies. 
 217. Sensors 2019 ,19, 743 Figure 4. The average subsidence velocity in LOS from October 2015 to June 2018 across Wuhan city by using SBAS-InSAR technique. 
 IR missile slaving co-aligns radar and seeker. Since gun effective ranges  are very short, gun ranging causes the radar to sense the gun field of fire, predicts  angle rate, and measures range to a target for tentative gunfire.9 It may also track gun  rounds during fire. There are thousands of electrical degrees of phase between free space and the A/D  converters. 
 HF radar has sufficient sensitivity to measure the relative amplitude of  the waves running against the wind, even though they may have a power spectral  density (and hence an RCS) several orders of magnitude below those running with  the wind. These upwind-propagating ocean waves are caused predominantly by third- order nonlinear wave-wave interactions, reflection processes, wave-current interac - tions, and propagation from neighboring regions with different wind stress. They are  very important for remote sensing and impact strongly on target detection because the  second-order scattering processes are heavily dependent on G(f , k). 
  
 648-652, September, 1972.  85. Taylor, J. 
 WATT TRANSISTORS JUST DESCRIBED (OWEVER  WITH A  DUTY CYCLE THE  
 PENSATE FOR AMPLITUDE ERROR  IT IS POSSIBLE TO COMBINE THE TWO TECHNIQUES BY PROPERLY SCALING AND APPLYING THE DIFFERENCE PATTERN BOTH IN PHASE AND IN QUADRATURE 4HE SCALING FACTORS ARE CHOSEN TO MAXIMIZE THE IMPROVEMENT FACTOR UNDER CONDITIONS OF SCANNING AND PLATFORM MOTION 4HE RELATIONSHIPS FOR A DOUBLE 
 3.28. The fairly simple Least Mean Squared  algorithm generally yields fairly slow convergence rates. Other algorithms19,23 can  speed up the adaptation rate, but a more complex mechanization is required. 
 Descriijtions presented in this chapter of radar scattering from the land and the sea are by  no means complete. Perhaps the chief difficulty in trying to understand the nature of clutter is  the lack of adequate quantitative descriptions of the nature of the scattering objects. In this  respect, the information regarding radar scattering from the sea is probably better understood  than radar scattering from the land. 
 II, there was an option to display ‘North-up ’, which was easier to interpret for navigation. The lack of a ‘North-up ’option on the ASV Mk. III may partly have been due to a shortage of DR compasses for the CoastalCommand Wellington aircraft [ 7]. 
 PRESSED BY ADAPTIVE APERTURE TAPERING  LOW 
 The sig - nal is then processed using a pulse compression filter that consists of a matched filter  to achieve maximum signal-to-noise ratio (SNR). As discussed below, the matched  filter is followed by a weighting filter if required for reduction of time sidelobes. The  output of the pulse compression filter is applied to an envelope detector, amplified by  the video amplifier, and displayed to an operator. 
  
  PI\ )N THE MONOSTATIC CASE    E    n   A     AND  PS   PI )N 
 ANGLE RADAR SEA RETURN AT  
 Moreover, the speckle in radar images is not present in photographs. Modern imaging radars use digital recording and processing, and the images are  produced on film or manipulated digitally. Because the side-looking configuration  produces a strip image, the output films are usually in the form of long strips. 
 SIDEBAND VALUE BY SUB 
 9Ê 
  ON %.6)3!4 !LL SHARE THE  SAME ORBIT  CALENDAR DAYS REPEAT PERIOD n INCLINATION AND  
 If the  echo pulse-train did contain additional modulation components, caused, for example, by a  fluctuating target cross section, the tracking accuracy might he degraded, especially if the  frequency components of the fluctuations were at or near the conical-scan frequency or the  sequential-lobing rate. The effect of the fluctuating echo can be sufficiently serious in some  applications to severely limit the accuracy of those tracking radars which require many pulses  to be processed in extracting the error signal.  Pulse-to-pulse amplitude fluctuations of the echo signal have no effect on trscking accur-  acy if the angular measurement is made on the basis of one pulse rather than many. 
 It is known from the theory of blackbody radiation that any  body wliicli absorbs energy radiates the same amount of energy that it absorbs, else certain  portions would increase in temperature and the temperature of other portions would  de~rease.'~ Therefore a lossy transmission line absorbs a certain amount of energy and rera-  diates it as noise. The same is true of tlie atmosphere since it also attenuates or absorbs  microwave energy. The radiation arising in the atmosphere (or any other absorbing body)  must just compensate for the partial absorption of the blackbody radiation. 
 , l og ( )/ 9 64 1 010 0 1 stcΣ) )+    { }21 lnPfa (24.16)  where g0(tj k-1) is the most recent available estimate of the jammer power level; the  value bk = 9.64 dB is the one which allows, in the absence of jammers, the desired  false alarm probability Pfa = 10-4; rk|k is the filtered estimate of the target range; Gstc(.)  is the sensitivity time control gain; and Σkj is the normalized antenna gain for the  received signal computed in the radar active mode.161 Because the phased-array radar considered here is a multifunctional one, it has also  a tracking mode that might be affected by the RGPO; for this reason, an A-RGPO is  considered an ECCM technique. Whenever RGPO is active, two high-amplitude signals  are received from the radar: the true target’s echo and an RGPO-induced signal. Since  the time at which the target under track activates RGPO is unknown to the tracking  algorithm, the latter must first recognize that RGPO is active and then implement an  appropriate A-RGPO technique. 
 76. Kanevskii, M. B.: The Propagation of Millimeter and Centimeter Waves in Tropospheric Waveguides  Close to the Sea, S<wiet Radiophysics, vol. 
 Figure 13. Frame diagram for near-ﬁeld InISAR imaging system in anechoic chamber. T able 4. 
 T. Kozu, T. Kawanishi, H. 
  
 NEOUSLY PROVIDE THE LOWER DATA RATE TRACKING OF MULTIPLE TARGETS SIMILAR TO THAT PERFORMED BY !$4 )MAGING RADAR 4HIS RADAR PRODUCES A TWO 
 SIDEBAND NOISE IS INCREASED BY  D" BECAUSE BOTH SIDEBANDS AFFECT SYSTEM STABILITY  AND THE POWER INTEGRATION IS ONLY CARRIED OUT FOR POSITIVE FREQUENCIES AND BY AN ADDITIONAL  D" BECAUSE THE OSCILLATOR INTRODUCES NOISE IN BOTH THE UPCONVERSION TO THE TRANSMITTED SIGNAL AND IN THE RECEIVER DOWNCON 
 E. Evans, “Target generated range errors,” in IEEE Int. Radar Conf. 
 It provides the greatest-ranges for a single refraction and can  support the highest usable frequencies. The F, region, from about 180 to 240 km, is observed  only during the day and is more pronounced during the si~mmer than the winter. T11e E region,  which lies between 100 and 140 km, can also support refraction. 
 Williams, R. Yee, and H. C. 
 ORBIT AS A CLOSELY COORDINATED PAIR TO SUPPORT A VARIETY OF BISTATIC AND INTERFEROMETRIC APPLICATIONS /THER 3PACE 
 Skolnik (ed.),  McGraw-Hill Book Company, New York, 1970.  8. Neuf, D., D. 
 Spectra Meteorol.  Variables, Radio Sci ., vol. 4, pp. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.56  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 have identical responses, and the filters will be uniformly spaced along the doppler  axis. The number of filters implemented for a given size of the CPI can, however,  be varied. 
 The complex envelope of x(t) is given by  u t a tej t( ) ( )( )=φ (8.39 a)TABLE   8. 10 Signal Analysis Definitions and Relationships ( Continued )  6 Cosine and sine functions expressed  in terms of complex exponentialscos ( ) sin ( )θ θθ θ θ θ= + = −− −e e e e jj j j j2 2  7 Parseval’s theorem  (superscript asterisk indicates  complex conjugate)x ty t dt X f Y f df x t dt X( )( ) ( ) ( ) | () | |−∞∞ ∗ −∞∞ ∗∫ ∫= =2( ( )|f d f2 −∞∞ −∞∞ ∫ ∫  8 rect function rect( )tt t=< >  1 1 2 0 1 2, || , ||  9 sinc functionsinc( ) sin( ) ( ) f f f = π π 10 Repetition operator repT nx t x t nT [ ()] ( ) = − =−∞∞ ∑ 11 Comb operator combF nX f X nF f nF [ ( )] ( ) ( ) = − =−∞∞ ∑ δ 12 Sampling property of delta function x t t t dt x t ( )( ) ( ) −∞∞ ∫− =δ0 0 13 Cauchy-Schwarz inequality f xg xdx f x dx g x dx ( )( ) | ( ) | | () | −∞∞ −∞∞ −∞∞ ∫ ∫ ∫≤2 2 2 withequalityifandonly if ()1 f x k g=∗( ( )x ch08.indd   37 12/20/07   12:51:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 tb represents the extra blanking time after the transmit pulse to allow for receiver/protector recovery .GATE 5 GATE 4 GATE 3 GATE 2 GATE 1 TRANSMIT 5τs 4τs 3τs 2τs τs 6τsτbACTIVE RECEIVE TIMERECEIVER RECOVERY TIMETRANSMIT  TIMEBLANKED RECEIVE TIME τs τt0τg ch04.indd   9 12/20/07   4:52:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 E.: Extraction of Wave Parameters from Measured HF Radar Sea-Echo Spectra, Radio Sd., vol. 12, no. 3, p. 
 It is most likely to occur, however, In the late  afternoon and evening when the warm afternoon air drifts out over the sea."  Thus the character of ducting is likely to differ over land and sea. Land masses change  temperature much more quickly thari'does the sea. As a result. 
 The agreement between ground  test data for I-second averages and the in-orbit data com- Johns Hopkins APL Technical Digesl, Volume 8, Number 2 (1987) MacArthur , Marth, Wall -The GEOSA T Radar Altimeter  91~----~-----.------.------,-----.  90 E u 89  E 88 Cl  ~ 87  860 Calibrate mode step 30  100 200 500  Days from turn-on  Figure 10-Long-term height drift as monitored by an in-flight  calibration mode has been less than 1 centimeter. The nega­ tive peaks are anomalies that occur during periods of full sun. 
 BOUNCE  "RAGG  OR VOLUME  OF A SCENE MAY BE SEPARATED FROM OTHER TYPES  THENCE SUBJECTED TO INTERFEROMETRIC ANALYSIS 5SING SUCH TECHNIQUES  IT IS POSSIBLE TO ESTIMATE THE TOPOGRAPHY OF THE SURFACE BENEATH A VEGETATED CANOPY  FOR EXAMPLE !PPLICATIONS  3!2S ARE THE LARGEST CLASS OF SPACE 
 However, the three signals may sometimes be  combined in other ways to perform with a two-channel receiver system (as described  later in this section) used in some current surface-to-air missile (SAM) systems. Monopulse-Antenna Feed Techniques.  Monopulse-radar feeds may have any of  a variety of configurations. 
 When circular  polarization is needed in a paraboloid-type antenna, square or circular cross-section  horn throats are used. The vertical and horizontal components from each horn are  FIGURE   9.6  Use of retracted septum to shape the sum-signal E field FIGURE   9.7  Four-horn triple-mode feed ( after P . W. 
 Friedland, “Optimum steady state position and velocity estimation using noisy sampled posi - tion data,” IEEE  Trans . vol. AES, p. 
 Remote Sens. 2017 ,38, 6319–6345. [ CrossRef ] 16. 
 CIENCYSOMETHING UNATTRACTIVE IN HIGH 
 These are known as grat~ity waves.  The effect of the large water waves is to cause a tilting of the scattering surface of the  smaller water waves, as in Fig. 13.6. 
 BEAM CLUTTER IS LESS OF A LIMIT THAN GROUND MOVING TARGETS  WHICH HAVE  VERY LARGE CROSS SECTIONS AND EXO 
 Lucas, J. L. Lloyd, J. 
 If the feed far-field H-field pattern is H v(ˆ), polarized in the direction ˆv, then the  incident H-field at the reflector is  H H v v n e dA r = ⋅−(ˆ) (ˆ ˆ) /jkr4π (12.34) Combining Eqs. 12.34 and 12.33 yields the equivalent surface current Jat area dA  J n H v v n e dA r = × ⋅−2 4 ˆ (ˆ) (ˆ ˆ) /jkrπ (12.35) where ˆnis the normal to the surface, ˆsis the observation direction (Figure 12.34), r is  the distance from the feed to the reflecting surface, k = 2p /l, i.e., the wavenumber,  and the e−jkr/4p�r term accounts for the propagation phase and space loss from the feed  to the reflector surface. FIGURE 12. 
 Each overlapping beam must be  compensated for the antenna look angle before the beams can be summed for a terrain  height estimate from all the beams.8 The radar cross section of the terrain could be  quite low (e.g., snow-covered level treeless terrain), so some pulses may be integrated  coherently to improve signal-to-noise ratio for a CPI of up to 8 pulses, as shown in the  TF/TA entry in Table 5.1. Terrain Database Merging.  For the purposes of safety as well as stealth, active  radar measurements are merged with a prestored terrain database.87 Figure 5.27 shows  the general concept of merged TF/TA measurements with stored data. 
 TIME AVERAGED DOPPLER SPECTRA AT 8 BAND FOR AN  INTERMEDIATE GRAZING ANGLE OF  SPECTRA COMPUTED AT  SEC INTERVALS  SHALLOW 
 Croney, J.: Doubly Dispersive Frequency Scanning Antenna, Microwm·e J., vol. 6, pp. 76-80, July,  196J. 
 HERENT VOLUME CONTRIBUTION FROM THE THOUSANDS OF INTERNAL CELLS COMPRISING THE FOAM MATERIAL   4HE COLUMN SHOULD BE DESIGNED SO THAT ITS SURFACES ARE NEVER CLOSER THAN   TO  TO THE LINE OF SIGHT TO THE RADAR DEPENDING ON FREQUENCY   THEREBY MINIMIZ 
 Olin, and V. Cavaleri: High-Resolution Radar Scattering Character-  istics of a Disturbed Sea Surface and Floating Debris, Nutul Resurc.lr Lcrhorutory Kcport H 13 1,  Washington, D.C., July 29, 1977.  11. 
 TATION OF AN OUTPUT SAMPLE BEFORE THE NEXT OUTPUT SAMPLE CAN BE FORMED #OMPLEX &)2 FILTERS  WHERE A COMPLEX MULTIPLICATION IS PERFORMED AT EACH TAP  CAN BE USED TO IMPLEMENT EQUALIZATION FILTERS  TIME DELAYS  AND PULSE COMPRESSION FILTERS &IGURE  SHOWS AN ALTERNATIVE FORM FOR A  &)2 FILTER  CALLED A  TRANSPOSED FORM &)2 FILTER )N  THIS CONFIGURATION  EACH INPUT SAMPLE IS MULTIPLIED BY ALL OF THE COEFFICIENTS AT ONCE  WITH THE SAMPLE DELAYS BETWEEN THE SUMMER OUTPUTS )F THE COEFFICIENTS OF A &)2 FILTER ARE SYMMETRIC   SO THAT THE COEFFICIENTS ON EITHER SIDE OF THE CENTER OF THE FILTER ARE MIRROR IMAGES OF EACH OTHER AS IS THE CASE WITH LINEAR PHASE FILTERS   MULTIPLIERS CAN BE SAVED BY ADDING THE SAMPLES THAT GET MULTIPLIED BY THE SAME COEFFICIENT FIRST  THEREBY REQUIRING ABOUT HALF AS MANY MULTIPLIERS  AS SHOWN IN &IGURE  FOR A  
 It may be written as W(K9 O), where K is the wavenumber for the surface. In terms of the wavelength on the surface A, K = 2>n/A Thus the component of the surface that satisfies the Bragg resonance condition is A = X/2 sin 9 (12.8) The meaning of this is that the most important contributor to a surface return is the component of surface roughness with wavelength A. Even though other com- ponents may be much larger, the Bragg resonance makes this component more important. 
 2009 ,47, 224–237. [ CrossRef ] 3. Migliaccio, M.; Gambardella, A.; Tranfaglia, M. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.476x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 noise and clutter energy being superimposed on the wanted radar echoes, either addi - tively or multiplicatively. Hence, careful attention to receiver design is imperative if  the radar designer wishes to avoid self-inflicted performance limitations.117 Attempts to reduce contamination from external broadcast signals by inserting nar - row-band filters at the receiver front-end sacrifice the high agility that is needed when  the radar is changing frequency, typically by several MHz, second by second, as it  jumps between tasks. 
 Other controls are as in Fig. 24.11.Local TimeHeight (km) Height (km) . 24.70 SKY-WAVERADARPERFORMANCE The performance index used in this section will be the signal-to-noise ratio (SNR) indicated when using the transmission-medium model treated in Sec. 
 FREQUENCY DISTRIBUTIONS  FOR MANEUVERING TARGET DETECTION IN OVER 
 The first sweep reads the signal on the storage tube. The next sweep is written on the same  space and generates the difference between it and the first sweep, as required for two-pulse  MTI cancellation. Two storage tubes are required: one to write and store the new sweep, the  other to subtract th~ new sweep from the old sweep. 
 WAVE STRUCTURE  THE STRUCTURE CAN BE LARGE  AND IT IS THEN POSSIBLE TO GENERATE QUITE HIGH POWER AT MILLIMETER 
 Acontract forthe production ofthk equipment, the SCR-270 (and SCR-271; seeSec. 6.9) was letinAugust 1940. British radar was developed atabout thesame time butitsapplication proceeded atasomewhat faster pace under the immediate threat to England and with considerably greater realism during theearly years of thewar. 
 The advantages are as follows: (1) The mirror and  its drive mechanism are the only moving parts for beam movement. The feed and  radome-supported paraboloid remain fixed. (2) The beam movement is by specular  reflection, twice the angle of the mirror tilt. 
 61 These  data assume (I) vertical.polarization, (2) the antenna located on a seacoast and looking over . 200  (l} 3 150 --0  L..  (l} a. 
 20(Q)FT,.L' L~NO1I~'l'I R{MOTING I REMOTtUNIT Figure14.9diockdiagram oftheASR-8airportsurveillance radar.APGistheazimuth puisegenerator whichprovides antenna timinginformation, andCJBisthecablejunction box.(Courtesy ofTexas InstI"lIIIICIltS. 11Ic.) User'srequirements. Sincethedesignofaradarisstrongly influenced bythetaskitisto accomplish. 
 V.: Range Resolution of Targets Using Automatif Detectors, Naoal Research Laboratorjf  R(*pr. 81 78. Nov. 
   *IANBING 
 Each system incorporates primary surveillance radar, sec - ondary surveillance radar (IFF), command and control display consoles, communica - tions equipment, various options, and transport configurations customized for each  customer’s specific mission.FIGURE 13.42  COBRA phased array mounted on radar system  vehicle ( Courtesy of Lockheed Martin Corporation ) FIGURE 13.43  Front (left) and rear views of Volume Search Radar S-Band engineering development  model active phased array mounted in near-field test facility during assembly. Rear view shows detail of  easily replaceable lowest replaceable units. ( Courtesy of Lockheed Martin Corporation ) ch13.indd   63 12/17/07   2:41:09 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 84. Ilhagavan. 13. 
 28 of" Radar Handbook," M. I. Skolnik (ed.). 
 13.16 gives  Gs e( ) cos q q =  42 πλ  When the element spacing is s = l/2, then the power pattern of an element that is  perfectly matched at all scan angles is  Ge(q ) = p cos q (13.18) And the peak antenna gain in the direction of scan, q0, is  G(q0) = p Nh cos q0 (13.19) where the efficiency term h  accounts for losses and for a nonuniform aperture distri - bution. For a broadside beam q0 = 0 and  G0 = p Nh (13.20) and the element gain is Ge = p. Figure 13.7 shows a theoretical example of the array and element factors and the  resulting pattern for a 10-element array, with element spacing s = l /2, scanned to 60 °. 
 AIR COOLING WAS PROVIDED IN THE EVENT OF A PRIMARY 
 AZIMUTH ASPECT ANGLE a (degrees) FIG. 11.28 RCS of a cone frustum, vertical polarization. (Copyright 1966, IEEE.38) Y1 = - tan [(<|>, + 4>,)/2] (11.29) X2= tan [(4>,-4>/)/2] (11.30) F2= - tan [a-(<|>, + <h)/2] (11.31) Because the PO diffraction coefficients depend on whether the upper face, the lower face, or both faces of the wedge are illuminated by the incident wave, the diffraction coefficients are combined differently in the three recognizable sectors defined in Eqs. 
 The relative advantages ofthe two types ofreceiver will now be considered. Ifthelin-log receiver isused, itispossible todispense with. 648 MOVING- TARGET lNDICA TION [SEC. 
 MENT LEVEL DUE TO THE SIZE  WEIGHT  AND HIGH COST OF DIGITAL RECEIVERS !NOTHER PRACTICAL ADVANTAGE OF SUBARRAY 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 24.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 Systolic Schemes for SLB and SLC.  In the quest for efficient parallel processing,  the systolic schemes come into the scene; their use has been described for the imple - mentation of SLC and more general adaptive array problems in the literature34,74,75 The  rationale and the use of a systolic array that processes the signals received by SLC and  main channel is reported on pages 146–156 of Farina34 and in Farina and Timmoneri.73  Figures 1 to 473 depict the use of a systolic processing scheme that incorporates the  SLB and SLC. 
 Ricardi and L. Niro, “Design of a twelve-horn monopulse feed,” IRE Int. Conv. 
 ELECTRONIC COUNTER-COUNTERMEASURES  24.556x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 The accuracy and detail of the model may vary from a coarse functional description  of the system to a very accurate one, according to the purpose of the simulation and  the required accuracy of the results. However, it is desirable to limit the complexity  of the simulation tools in order to have manageable programs, giving results that are  easily interpreted. The accuracy in representing each system function depends upon  its relevance with respect to system performance. 
 [ CrossRef ][PubMed ] 9. Wang, Y.; Song, Y.; Lin, Y.; Li, Y.; Zhang, Y.; Hong, W. Interferometric DEM-Assisted High Precision Imaging Method for ArcSAR. 
 TION ALONG THE LINE 
 h  m–1 7 × 10–93 × 10–91.7 × 10–910–9 Rain    (for rate r mm/h)h = 6 × 10−14 r1.6 l−4 (matched  polarization)r = 4 mm/h h  m–1 2 × 10–105 × 10–95 × 10–85 × 10–7 *From Barton12 ch02.indd   17 12/20/07   1:43:53 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 RADAR RECEIVERS  6.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 and when the limiter is fully saturated and the output waveform is rectangular, it is  given by the Fourier series:  ′= =∞ ∑ vE nn to n4 1 1 35πsin( ) , , ,...w (6.24) which is an increase of 20 log (4/ p ) = 2.1 dB in the power of the fundamental. In practice, the amplitude performance is also degraded by capacitive coupling  between input and output of each limiting stage, charge storage in transistors and  diodes, and RC time constants that permit changes in bias with signal level. For these  reasons, two or more limiter stages may be cascaded when good amplitude uniformity  is required over a wide dynamic range. 
 SQUARED PATTERN IS TYPICALLY MODIFIED TO ACCOUNT FOR THE CURVATURE OF THE EARTH AND THE CHARACTERISTICS OF SENSITIVITY TIME CONTROL 34#  &)'52%   0ARABOLIC CYLINDER A  GEOMETRY AND B  SURFACE EXTENSION ENABLES LINE  SOURCE STEERING. £Ó°Óä  2!$!2 (!.$"//+  ! RELATIVELY SIMPLE WAY TO SHAPE THE BEAM IS TO SHAPE THE REFLECTOR  AS &IGURE   ILLUSTRATES %ACH PORTION OF THE REFLECTOR IS DESIGNED TO REFLECT A PORTION OF THE INCI 
 DOPPLER COUPLING OF THE CLUTTER  (OWEVER IN /4( RADAR  MAIN BEAM AND SIDELOBE CLUTTER FROM A SINGLE IONOSPHERIC MODE TYPICALLY HAVE SIMI 
 TION SHOULD BE OPTIMIZED MAINLY FOR GOOD EXTENDED TARGET INTERPRETATION  ACCOUNTING FOR ALL KIND OF BACK 
 L Solem, and R. F. Van Wye:" Regulations, Standards, and Guides for  Microwaves. 
 Wilsori. and J. J. 
 This same technique can be applied to many different  radar-tracking problems using the equations in Table 7.3 to calculate a graph such as  the one shown in Figure 7.27. For simple tracking problems, the a-b   filter with constant gains selected for the appli-   cation will often be adequate. However, more complex tracking problems require vari - able tracking gains (e.g., larger gains at the beginning of the track and larger gains after  missed detections or when the range to the track decreases, making angle noise less of  an issue). 
 28,  pp. 554-575, September, 1926.  5. 
 When all the  cavities are tuned to tlie same frequency, the gain of the tube is high, but the bandwidth is  narrow, perhaps a fraction of one percent. This is known as synchronous tuning. Although  maximum gain is obtained with all cavities tuned to the same frequency, klystrons are often  operated with the next to the last cavity (the penultimate cavity) tuned outside the passband  on tlie high-frequency side. 
 STATE TECHNOLOGY HAD ADVANCED SUFFICIENTLY SO THAT .ORTHROP 'RUMMAN DEVELOPED THE !32 
 The reported performance characteristics of transceiver modules are generally a combination of multiple MMIC chip configurations and/or multiple-chip configu- rations with additional hybrid components to augment the performance of the GaAs components. In addition, the complexity of the transmit/receive functions varies among the module configurations. Data for various modules is enumerated in Table 5.4.15'16'17 An integrated transceiver module that operates in the X-band frequency range is shown in Fig. 
 CHAPTER  FIVE  TRACKING RADAR  5.1 TRACKING WITH RADAR  A tracking-radar system measures the coordinates of a target and provides data which may be  used to determine the target path and to predict its future position. All or only part of the  available radar data~range, elevation angle, azimuth angle, and doppkr frequency shift  may be used in predicting future position; that is, a radar might track in range, in angk, in  doppler, or with any combination. Almost any radar can he considered a tracking radar  provided its output information is processed properly. 
 Among the runs of ones and zeros in each sequence, one-half of the  runs of each kind are of length one, one-fourth are of length two, one-eighth are of length three,  and so on (the run property). If the sequence is compared term by term with any cyclic shift of  itself, the number of agreements differs from the number of disagreements by at most one (the  correlation property). These sequences are called linear since they obey the superposition  theorem. 
 Correct methods ofmatching areshown inFig. 131 lc. Another special case ofFig. 
 CLUTTER SIGNAL RATIO FOR TARGETS AT HIGH ELEVATION  ANGLES  THUS IMPROVING -4) PERFORMANCE 4HE PENALTY FOR THIS SOLUTION IS A LOSS IN THE  PEAK ANTENNA GAIN THAT CAN BE ACHIEVED !N ILLUSTRATION OF THIS APPROACH IS PROVIDED IN &IGURE   WHICH SHOWS BOTH THE !232 
 1973.  103. Richter. 
 TRACING ROUTINES TO A DATABASE OF 24)- SNAPSHOTS 7HEN A RADIOWAVE PROPAGA 
 Head-up maximizes the relationship to the visual  scene, and North-up aids comparison with paper charts. Nowadays, Course-up is also  provided, as this eliminates small oscillations in the radar image due to the ship’s yaw  that occur when the display is set to Head-up. Each of these directional modes can be  set with target tracking vectors shown as relative to the motion of the ship, the ground,  or the average sea motion. 
 Itisdifficult toconceive, however, ofareceiverthatcomputes thelikelihood ratiodirectlyas definedbyEq.(10.21).However, incertaincasesthereceiver whichcomputes thelikelihood ratioisequivalent toareceiver whichcomputes thecross-correlation function ortoonewitha matched-filter characteristic, thatis,onewhichmaximizes theoutputsignal-to-noise ratio.24 TheNeyman-Pearson Observer isequivalent toexamining thelikelihood ratioanddeter­ miningifLr(v)~K,whereKisareal,nonnegative numberdependent upontheprobability of falsealarmselected. Im'erseprobability receiver. Adetection criterion thathasbeenpopular particularly forthe theoretical analysis ofstatistical detection andforstatistical parameter estimation isthat basedoninverseprobability. 
 Since 2002, he has delivered lectures onSAR/InSAR principles and techniques for the Master’s program in “Spaceborne Remote Sensing”at Bari University. He has been co-advisor for several degree theses in Physics and ElectronicEngineering on SAR processing, SAR interferometry, and their applications. He is also a boardmember of the IEEE Geoscience and Remote Sensing South Italy Chapter. 
 Low sidelobes are generally desired for radar applications. If too large a portion of the  radiated energy were contained in the sidelobes, there would be a reduction in the main-beam  energy, with a consequent lowering of the maximum gain.  No gqieral rule can be given for specifying the optimum sidelobe level. 
 Applications ofEq. (14) are tobefound in the fields ofmicrowave radar relay, radar jamrning, and microwave communication. THE MINIMUM DETECTABLE SIGNAL 2.7. 
 Results for the SAR dataset. Methods FP FN OE PCC (%) KC (%) Time (s) NR-ELM 97377 4276 101653 0.9031 0.2993 202.1 GaborTLC 20160 8449 28609 0.9727 0.5809 74.6 PCAKM 35135 6251 41386 0.9605 0.51 6.4 Proposed method 3865 12852 16717 0.9841 0.6569 199.1 In addition to these results, the proposed framework was tested on an ensemble of 1024 ×1024 regions from the same SAR dataset. In many representative image regions where registration errors were prevalent, false positive detections were reduced by over 60%. 
 on Radar , Radar 2005, Washington, DC  (USA), May 10–12, 2005, pp. 37–42. 27. 
 SURFACE BEHAVIOR &IGURE A SHOWS A NUMBER OF FACETS OF DIFFERENT SIZES CONTRIBUTING TO A RADAR RETURN. 
 Anecho fluctuation ofthistypewillbereferredtoasscan-to-scan fluctuation. Theprobability- • Il... THE RADAR EQUATION 47  dcrlsity rrrrlctiorl far tllc cross scctioll rr is given by tlle density function  wllere n,, is tlic avcriigc cross section over ail target liuctuations. 
 Yttrium iron garnet (YIG) filters and pin  diode switched filters have been used to provide the necessary frequency agility. ch06.indd   9 12/17/07   2:03:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 C. Dodson: Parasitic Spiral Arrays, IRE Intern. COIIV. 
 Multiple decoys are sometimes dispensed at predeter - mined rates in order to improve the cumulative probability of aircraft survival.  A towed decoy  is a small aerodynamically stable body that houses a miniature jam - mer. The decoy is deployed by reeling it out on a cable behind the aircraft to a fixed  distance or offset. 
 Values of yt = 0° and 180 ° are horizontal polarization, whereas yt = 90° is ver - tical polarization. Linear polarization occurs when ct = 0°, and right and left circular  polarizations occur when ct = ±45°. When the minimum is above zero, the pedestal  beneath it corresponds to the unpolarized signal. 
 FREQUENCY CONTOURS ARE GIVEN IN -(Z  EXTENDING FROM THE RADAR  TO A POINT EAST  NMI DOWNRANGE  FOR A *ANUARY DAY EXAMPLE . 
 ARRAY FEED ARRAY IS APPROPRIATELY DESIGNED  BEAM DISTORTION AND SCAN LOSSES SUCH AS THOSE SHOWN IN &IGURE   CAN BE EFFECTIVELY ELIMINATED 4HIS SORT OF DESIGN APPROACH WHEREIN THE FEED ARRAY AMPLITUDEPHASE DISTRIBUTION IS hMATCHEDv TO THE FOCAL PLANE FIELDS IS OFTEN REFERRED TO AS CONJUGATE FIELD MATCHING  &)'52%   0ATTERNS FOR OFF 
 SEC. 2.10] THESTATISTICAL PROBLEM 35 uct ofthe received signal power Sand the pulse duration 7isjust the energycontained inthe received signal pulse, while kTisthe average stored energy inaquiescent system with one degree offreedom. That the ultimate criterion ofdetectability should involve acomparison of these two quantities iscertainly not surprising. 
 MTI or pulse-doppler radar is also necessary in radar carried by high-flying  aircraft that must detect other aircraft masked by sea clutter.  Altliougli sllips arc rnoving targets that miglit be candidates for MTI radar, it is not often  that MI'I is ticeded for this application. 'Tile large cross section of ships generally results in  sititable target-to-oluttcr ratios with convetltio~lal radars. 
 END LIMITERS ARE DISCUSSED IN MORE DETAIL IN 3ECTION  4HE RADAR OR RECEIVER FRONT END OFTEN INCLUDES SOME FORM OF GAIN OR ATTENUATION CON 
  TO TWENTYFOLD INCREASE  COMPARED TO CONVENTIONAL HIGH 
  
 13.3. The changes in clutter statistics  must be accounted for in the detector design, else the large signal-to-clutter ratios required of a  conventional threshold detector might negate any benefit of the shortened pulse. As mentioned  previously, a radar with a very short pulse (or narrow beamwidth) might prove to be worse  than one with a longer pulse (or a wider beamwidth) because of the change in clutter  statistics. 
 An example ofsuch acon- denser and onetype ofcircuit used is shown inFig. 13.7. The condenser plates aresoshaped that thecapacity increases astherotor turns clock- wise, producing thedesired potential variation (usually linear with angle) across C’O. 
 noncoherently integrated in each beam, the type and amount of target echo pulse- to-pulse fluctuation within a beam, and of the prevailing beam-to-beam correla- tion in target fluctuation. For N pulse returns noncoherently integrated within each beam on a nonfluctuating target, the asymptotic rmse accuracy performance of two-beam sequential lobing is given by /1 +/2V/2rmse - . J } (20.16) \2/ 2Nx/ where / = ratio of two-way elevation power patterns as before N = number of pulses noncoherently integrated jc = per-pulse SNR Since this form is the same as for a single pulse except for the factor of N in the denominator, numerical results may be obtained from Fig. 
 CHANNEL RECEIVER SYSTEM AS DESCRIBED LATER IN THIS SECTION  USED IN SOME CURRENT SURFACE 
 Space object  identification (SOI) radars are an example of those that extract target shape information. The  synthetic aperture radar (SAR) which maps the terrain is another example. Radars that  determine the shape of a target are sometimes called imagit1g radars. 
 REFERENCES  I. North, D. 0.: An Analysis or the Factors Which Determine Signal/Noise Discrimination in Pulsed­ carrier Systems, RCA Tech. 
 There-2-PRFRANGINGPARAMETER Pn1-I . fore, O < R0 < Wi1W2In3. The constants C1, C2, and C3 are related to ml9 m2, and /77.3 by the congruences C1 = ^1W2W3 = 1 (modulo /Tt1) (17.7) C2 = b2wlw3 = 1 (modulo /W2) (17.8) C3 = ^m1W2 s l (modulo /Ti3) (17.9) where ^1Is the smallest positive integer which, when multiplied by m2w3 and di- vided by W1, gives unity as the remainder (and similarly for the other 6's). 
 20.4« with appropriate scaling. Fundamental Accuracy of Simultaneous Lobing. In the simultaneous-lobing method of angle estimation, two or more radar receive beams are simul- taneously formed by the antenna and processed in parallel receive channels. 
 TERM RELIABILITY  IF OPERATED AT THE SAME POWER LEVEL FOR THE LONGER PULSE WIDTH 4HUS  IF REQUIRED TO 5NITS 3ILICON 'A!S )N0 3I# 'A. "ANDGAP %NERGY E6         2& 0OWER $ENSITY 7MM n n n n n$IELECTRIC #ONSTANT      "REAKDOWN &IELD   6CM         4HERMAL #ONDUCTIVITY 7M#     %LECTRON -OBILITY CM  6SEC      3ATURATED 6ELOCITY  CMSEC        4!",%  +EY 3EMICONDUCTOR #HARACTERISTICS OF THE 0RIMARY 3EMICONDUCTORS 5SED FOR 0OWER  'ENERATION IN 3OLID 
 The half-power video band\vidth ofthecoupling network between thedetector and thecathode follower is6Me/see. The noise figure determined from measuring approximately 100 such amplifiers ranged from 1.7to4.5db,with the a}-erage at3.3db. This amplifier was designed before the development ofthe grounded-cathode grounded-grid triode input circuit. 
 34-40, 84, March, 1977.  12. Neuf, D.: A Quiet Mixer, Microwarle J., vol. 
 SIDELOBE DESIGN  EITHER #7 OR PULSED  THE SIDELOBES FOR THIS FEED SHOULD BE CAL 
 SANDWICH  THE " 
 PHASE AND QUADRATURE DATA FROM EACH RECEIVE SITE IS COMBINED TO FORM A LARGE RECEIVE  APERTURE %XAMPLES INCLUDE THINNED  RANDOM  DISTORTED  AND DISTRIBUTED ARRAYS n INTERFEROMETRIC RADARS   AND THE  RADIO CAMERA  4HIS SUBJECT IS TREATED FURTHER IN 7ILLIS. 
 ICE MONITORING v * 'LACIOL  VOL   PP n    4 ,E4OAN ET AL  h-ULTITEMPORAL AND DUAL 
 DIMENSIONAL PROB 
 The polarization character - istics of a radar can be exploited as ECCM techniques in two ways. First, the cross- polarized pattern (i.e., the orthogonal polarization to the main plane of polarization)  of a radar antenna should be kept as low as possible consistent with radar system cost.  Ratios of copolarized main-beam peak gain to cross-polarized gain anywhere in the  antenna pattern should be greater than 25 dB to provide protection against common  cross-polarized jamming. 
 Li32 has described experiments  using a 10-ft-diameter spherical reflector at a frequency of 11.2 GHz. The focal length was  29.5 in. If the phase error from the sphere is to differ from that of a paraboloid by no more  than J/16, the maximum permissible diameter of the illuminated surface should be 3.56 ft. 
 Other features of the system include a self-monitoring and self-adjusting driver group power output level. The output level is monitored, and changes to the pro- grammable 24- to 40-V dc power supplies maintain a constant driver group output level as a function of time and temperature. NAVSPASUR. 
 32, no. 1, pp. 134−166, January 1996. 
 2013 ,51, 3156–3169. [ CrossRef ] 19. Li, Z.; Xing, M.; Liang, Y.; Gao, Y.; Chen, J.; Huai, Y.; Zeng, L.; Sun, G.-C.; Bao, Z. 
 Within the DSP, subtle software code and numeric  errors such  as poorly chosen  filter constants, numeric rounding, or  overflow errors  can create very short -duration artifacts  that  may bear little or no relation to the desired output.  A single  DSP error  can create momentarily incorrect RF output  (i.e. a  glitch). 
 Despite the generality of the initial formulations, most of the final  expressions for s  0 either appear in, or can be put into, a form represented schemati - cally by the following simplified one-dimensional expression (see Holiday et al.,10  Bechmann and Spizzichino,99 Fung and Pan,101 and Valenzuela,102 for example):  σ ψ ψ0 2 2 4 1 41 22 2( ) ( ) [[ ( )]= −− − −AkF dy e e epi ky k h C y k k h22 2] −∞∞ ∫ (15.12) where A is a constant; k1 = k cosy and k2 = k siny where k is the radar wave - number (2 p /l); Fp (y  ) is a function of polarization p, grazing angle y , and the  electrical properties of seawater; h is the rms sea waveheight; and C(y) is the surface  correlation coefficient. Of course, the reduction of a complicated boundary-value  problem to so simple a form requires assumptions about both the surface fields and  the distribution of the sea heights (which is gaussian to a good approximation20). But  while the SPM approach mentioned above requires the ratios h/l to be small right at  the start, GBVP theories derived from expressions resembling Eq. 
 The solid straight line plotted in Fig. 2.8a represents a perfect predetection integrator  with E,(n) 1. It is hardly ever achieved in practice. 
 The two-axis mount of (d) is similar to (c) except that it is arranged to provide roll  stabilization. The roll data from a stable vertical can be applied to the basic roll axis without  the need for computer orders as required in the other two-axis mounts. The antenna is then  stabilized about the azimuth axis if the pitch angle is small. 
 28. Klass, P. J.: Solid State 3D Radar for NATO Tested, Aviat. 
 Intcrfcrence fromotherradarsmightappearasonelargereturnamongthetenreturns normally processed. IntheMTD,aninterference eliminator compares themagnitude ofeach ofthe10pulsesagainstthcaverage magnitude oftheten.Hanypulseisgreaterthanfivetimes theaverage, allinformation fromthatrange-azimuth cellisdiscarded. Asaturation detector dctectswhether anyofthe10pulseswithinaprocessing intervalsaturates theAIDconverter andifitdocs,theentire10pulsesarediscarded. 
 Therateatwhichafan-beam antenna maybescanned isacompromise between therate atwhichtarget-position information isdesired(datarate)andtheabilitytodetectweak targets(probability ofdetection). Unfortunately, thetwoareatcddswithoneanother. The moreslowlytheradarantenna scans.themorepulseswillbeavailable forintegration andthe betterthedetection capability. 
 2.3, factors in the range equations were defined, and some information on how to evaluate them in typical cases was given. However, several very impor- tant factors were not covered because they are of sufficient importance to war- rant more extensive treatment in separate sections. In this section and in Sees. 
 3 dB Definitions. In the interest of making possible direct measurement of parameters from oscilloscope waveforms or pen recordings of these functions, it has been customary to utilize widths measured either at half-power (3 dB) or half- voltage (6 dB) points. For functions that resemble a gaussian pattern, the 3 dB width is a close approximation to the energy width; the receiver bandpass gener- ally fulfills this condition sufficiently to make the 3 dB bandwidth meaningful. 
 This  radar system is characteristic of the technologies currently in place in the research   community. Polarimetric Radar.  Meteorological radars using dual polarization transmit and  receive both horizontal and vertical polarizations to estimate additional characteris - tics of the weather targets.13,14,24 Transmitting the two orthogonal polarizations either  simultaneously (SHV) or transmitting them separately in a predetermined sequence  and using dual parallel digital receivers (one on each polarization channel) allow esti - mation of the differential quantities between echoes from the two polarizations. 
 Systematic errors are determined by prior measurement and are used to adjust the  encoded antenna position to provide the correct target position. Systematic errors include  (l) error in the zero reference of the encoders that indicate the orientation of the radar axes,  (2) misalignment of the elevation axis with respect to the azimuth axis (nonorthogonality),  (3) droop or flexing of the antenna and mount caused by gravity, (4) misalignment of the radar  with respect to the elevation axis (skew"), (5) noncoincidence of the azimuth plane of the mount  to the local reference plane (mislevel), (6) dynamic lag in the servo system, (7) finite transit  time that results in the target being at a different position by the time the echo is received by  the radar, and (8) bending and additional time delay of the propagation path due to atmo­ spheric refraction.  A boresight telescope mounted on the radar antenna permits calibration of the mechani­ cal axis of the antenna with respect to a star field. 
 B., D. H. Mooney, and W. 
 5.4 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 vehicle management, pilot-vehicle interface, and integrated core-processing suite. There  is substantial data traffic between the core processing and the sensors to provide point - ing, cueing, tracking, and multisensor fusion of detections. The aim of this approach is  to provide a shared pool of computational resources, which may be flexibly allocated  between sensors and functions. 
 Locke, Ref. 25.) . above equation. 
 Dokka, G. Sella, S.-W. Kim,   S. 
 R. J. McAulay and T. 
 Italso presents thepossibility ofapplying modulation tothereflection from acorner by slight motion ofone side. 3.6. Target Shaping toDiminish Cross Section.-A corner reflector gives aradar return byspecular reflection fornearly alldirections of 1R.C.Spencer, “Optical Theory oftheCorner Reflector,” RLReport No.433, Nfar, 2,1944,. 
 14. M. Skolnik, Radar Handbook , 2nd Ed., New York: McGraw-Hill, 1990, Chap. 
   PP n  .OVEMBER   2 # *OHNSON AND ( *ASIK EDS    !NTENNA %NGINEERING (ANDBOOK   ND %D  .EW 9ORK -C'RAW 
 On the other hand, ther  might be times when ionospheric,conditions allow this region to be covered by only a sing1  frequency, while at other times five or six frequencies might be required. This illustrates the  necessity for flexible management of the radar. The ionosphere must be sensed and the param-  eters of the radar adjusted to optimum operation. 
 Then follows a ‘drift space’ before the electrons cross  the opening of the second rhumbatron cavity, known as  the ‘catcher.’ The bursts of electrons passing between the  two cavities set up oscillations within. If you picture  the whistle set up by blowing across the lip of holes in a  penny whistle you will appreciate to some extent how  the klystron oscillates. The blast of air corresponds to  the stream of electrons, the holes in the whistle are the  lips of the rhumbatron cavities, and the resulting sound  is the oscillation in the tube. 
 STATE DEVICE  -OST OPERATIONAL (& RADARS EMPLOY  SOLID 
 Parameter Parameter V alue Carrier frequency 10 GHz Bandwidth 4 GHz Frequency step interval 40 MHz Azimuth accumulation angle 20◦ Azimuth sampling interval 0.2◦ Distance between antenna and target 2 m Baseline length 0.02 m Independent CS processing and joint CS processing based on global sparsity are separately used for InISAR imaging. The 3-D distribution of scattering points is shown in Figure 4. The above experiments are carried out with full data and signal without noise. 
  5332   6ENUS    2ADAR ALTIMETRY 0IONEER 6ENUS /RBITER  06/  53!  6ENUS n /2!$ !LTIMETER ALSO COARSE IMAGERY    CM 6ENERA  5332   6ENUS n 3!2 AND ALTIMETER  
 D. A. Fulghum, “Deep look,” Aviation Week and Space Technology , January 17, 2005. 
 CORRELATIONS BETWEEN THEM   IF A +ALMAN 
 Relaying the scanner data ismuch more complex. Itisnot feasible totransmit thenumerical value ofanangle byaproportional amplitude or frequency modulation ofanr-fcarrier. Itispossible todevise methods whereby certain functions (e.g.,thesine and cosine) ofthescan angle can beused tomodulate two ormore subcarriers’ directly bymeans ofslowly varying voltages; this has been done inthe laboratory. 
 The attenuator was a quarter-wave stub attached to the transmitter antenna feed, with sliding short circuit that could be moved along the stub, to provide perfect matching (zero attenuation) between the transmitter and Table 2.5. U-boat sightings before and after the introduction of Metox [ 14]. PeriodASV fitted Aircraft Non-ASV fitted Aircraft U-boat sightings Hours per sighting U-boat sightings Hours per sighting May –Sept 54 95 56 135 Oct–Feb 16 135 42 245Airborne Maritime Surveillance Radar, Volume 1 2-22. 
 ~-1  0.1  Clutter spectral width /radar prf  Figure 4.25 Improvement factor for an N-pulse delay-line canceler with optimum weights (solid curves)  and binomial weights (dashed curves), as a function of the clutter spectral width. (Afcer Andrews.31.32) . ro  "CJ 140  120  100  O 80 E  ~  ~ 60 -----,  > e  0  _E  40  20 . 
 Electron. Lett. 2016 ,52, 1406–1408. 
 I, January.  1974. 342 INTRODUCTION TO RADAR SYSTEMS  134. 
 MENT OF THE #OAXITRON  THE ELECTRON 
 Nickel, “Spotlight MUSIC: Superresolution with sub-arrays with low calibration effort,” IEE  Proc ., vol. 149, pt. F, no. 
 The radiation pattern  236INTRODUCTION TORADAR SYSTEMS determined bytheillumination ofthelinesource,whilethebeamwidth illtheperpendicular planeisdetermined bytheillumination acrosstheparabolic profile.Therdkc(or ismade longerthanthelinearfeedtoavoidspillover anddiffraction effects.Oneoftheadvantages of theparabolic cylinder isthatitcanreadilygenerate anasymmetrical fanbeamwithamuch largeraspectratio(lengthtowidth)thancanasectionofaparaboloid. Itisnotpractical touse aparaboloidal reflector withasinglehornfeedforaspectratiosgreaterthanaboutH:I, although itispractical tousetheparabolic cylinder foraspectratiosofthismagnitude or larger.Another advantage oftheparabolic cylinder antenna isthatthelinefeedallowsbetter controloftheaperture illumination thandoesasinglepointsourcefeedingaparaboloid. The patterns inthetwoorthogonal planescanbecontrolled separately, whichisofimportance for generating shapedbeams.Alsothereisusuallylessdepolarization inaparabolic cylinder than inaparaboloid fedfromapointsource.Sinceadirective feedisusedwithaparabolic cylinder, leakagethrough ameshreRector willcauseahigherbacklobe thanwouldaPOilH-source feed. 
 1:. (editor in chief): "IEEE Standard Dictionary of Electrical and Electronic Terms," 2d ed. John  Wiley Rr Sons, Inc., New York, 1977. 
 Theantennasystem takestheradio-frequencyenergyfromthetransmitter, radiates it in a highly directional beam, receives any returning echoes, andpasses these echoes to the receiver. Thereceiverampliﬁes the weak radio-frequency pulses (echoes) returned by a target and reproduces them as video pulses passed to the indicator. Theindicator produces a visual indication of the echo pulses in a manner that furnishes the desired information.duty cycleaverage power peak power-----------------------------------------= average power 200 kw x 0.001 0.2 kilowatt == Figure 1.13 - Block diagram of a basic pulse-modulated radar system . 
 D. Wilson, “Correlation of DF bearing measurements with radar tracks,” in  IEEE Int. Radar Conf ., London, 1987, pp. 
 The pattern maximum is noted to occur at less than 60° because the gain of the element pattern increases toward broadside. The pattern value at 60° is cos 60° = 0.5 in power or 0.707 in amplitude, relative to the maximum at broadside, as expected. The sidelobes in the general region of broadside are not reduced since in that region the element DEGREES FIG. 
 (There are certain monopulse implementations that can  use either one or two rcccivcrs, but at some sacrifice in performance.) Since the monopulse  radar conlpares the amplitudes of signals received in three separate channels, it is important  that the gain and phase shift through these channels be identical. The RF circuitry that  generates the surn and diKerence signals in a monopulse radar has been steadily improved, and  can be realized without excessive physical bulk. A popular forni of antenna for monopulse is  tllc Casseg~aill. 
 Consequently, the angular error as a rault ofampli-  tude fluctuations will also be independent of range.  Angle  fluctuation^.^^.^^ Changes in the target aspect with respect to thc radar can cailse the  apparent center of radar reflections to wander from one point to another. (The apparent center  of radar reflection is the direction of the antenna when the error signal is zero.) In general, the  apparent center of reflection might not correspond to the target center. 
 In addition to the insensitivity of electron emission with pulse duration,  there is also an insensitivity to duty cycle if the cathode is cooled sufficiently so that the  secondary emission properties of the cathode do not change with temperature." Thus high and  low duty-cycles can be employed interchangeably if the cathode temperature is maintained cool  enougtl, usually below about 400 or 500°C.  The noise and spurious signals generated by a CFA can be quite low when the tube is  locked in and controlled by an RF drive signal." Measurements of noise made with the  voltages applied but with the tube inactive because of no RF drive-signal, indicate the noise to  approach what would be expected from its thermal level. Intrapulse noise is generally much  higher. 
 As the physical antenna moves along the synthetic aperture, the return from a  point target at a particular range will exhibit a quadratic phase behavior (i.e., phase  varies as the square of the time referenced to the closest approach) that is unique to  the target’s location on the ground.2,17 Some stripmap SARs use a filtering approach  to take advantage of this phenomenon.11 In fact, for the echo from a point target in  the scene, a close analogy exists between its quadratic phase variation during a single  pulse (from a linear FM [LFM] pulse echo) and its quadratic phase variation over  many pulses due to platform motion (Stimson,5 p. 421). Other stripmap SARs divide  the strip into subpatches  and use spotlight-SAR processing (next section) for each  subpatch3 (see also Section 4.8 of Ausherman et al.11). 
 1974.  26. Barrick. 
 215 220. If:I!I~ Cat. no. 
 Kovaly, G. S. Newell, J. 
 NATED TURNS v 30)%  3IGNAL AND $ATA 0ROCESSING OF 3MALL 4ARGETS   VOL   PP n    2 #OOPERMAN  h4ACTICAL BALLISTIC MISSILE TRACKING USING THE INTERACTING MULTIPLE MODEL   ALGORITHM v IN  0ROC  &IFTH  )NTERNATIONAL  #ONFERENCE  ON  )NFORMATION  &USION   VOL       PP n  # , -OREFIELD  h!PPLICATION OF n INTEGER PROGRAMMING TO MULTI 
 Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar.  PULSE DOPPLER RADAR  4.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 which is essentially formed by dividing the aperture into two halves and subtracting  the corresponding phase centers. Monopulse beams, delta-azimuth ( ∆AZ) and delta- elevation ( ∆EL), are formed to provide phase monopulse azimuth and elevation angle  measurements.21 Self-calibration routines controlled by the control processor ensure  that the phase and amplitude match of the receiver channels enables accurate mono - pulse measurements. 
 5. FIG. 22.14 Schematic of the antenna module for Cosmos 1500.LOCKANTENNASECTION SWIVELMECHANISM SECTION OF SUPPORTINGSTRUCTURE SWIVEL MECHANISM . 
 Degrees off oxis C~tler,~ Proc. I RE.)  234INTRODUCTION TORADAR SYSTEMS -20Q) >'';:: 0 Q) L..-25N ~I'v ••-30 ~ -35 -10-8 -4-20 2 46 ~:;:27T(ro/A) sin<p Figure7.4Radiation patternforauniformly illuminated circularaperture, theblocking causedbythefeedanditssupports inreflector-type antennas. Aperture blocking degrades theperformance ofanantenna bylowering thegain,raisingthesidelobes, andfilling inthenulls.Theeffectofaperture blocking canbeapproximated bysubtracting theantenna patternproduced bytheobstacle fromtheantenna patternoftheundisturbed aperture. 
 Solid-state  devices also are less "forgiving" than microwave. tubes of transients due to lightning and  nearby radars. The advantage of long life claimed for solid-state transmitters seems matched  by the long life obtained with linear beam tube transmitters. 
 532–533, July 1974. 79. IEEE standard radar definitions, IEEE Std 686-1990, The Institution of Electrical and Electronic  Engineers, New York, NY , 1990. 
 J. W. Johnson, L. 
 8. L. E. 
 The null and H1 hypotheses correspond to the usual decisions of "no detection" and "target detection," re- spectively. The blanking command is delivered when H2 is detected. SLB performance can be expressed in terms of the following probabilities: (1) The probability PB of blanking a jammer in the radar sidelobes, which is the prob- ability of associating the received signals (u, v) with H2 when the same hypoth- . 
 Thus vertical  bulkheads often are tilted inboard.71 REFERENCES  1. E. F. 
 2.Mumford, W.W.,andE.Scheibe:" Noise:Performance FactorsinCommunication Systems," Hori­ zonHouse-Microwave, Inc.,Dedham, Mass.1968. 3.Goldberg, H.:SomeNotesonNoiseFigures, Proc.iRE,vol.36,pp.1205-1214, October, 1948. 4.VanVoorhis, S.N.(ed.):"Microwave Receivers," MITRadiation Laboratory Series,vol.23, McGraw-Hili BookCompany, NewYork,1948. 
 DUTY HIGH 
 A similar loss must be taken into account when  covering a search volume with a step-scanning pencil beam, as with a phased array/8 since not  all regions of space are illuminated by the same value of antenna gain.  Limiting loss. Limiting in the radar receiver can lower the probability of detection. 
 MAST ELECTRONICS OF THE RADAR ENVIRONMENTALLY AND PREVENTS THE ANTENNA FROM SNAGGING THE RIGGING )N PARTICULAR  IT ASSURES THAT THERE IS NO DANGER TO . ÓÓ°£Ó  2!$!2 (!.$"//+  USERS FROM ROTATING MECHANISMS  SINCE THE RADAR HEAD CAN BE MOUNTED IN AREAS OPEN  TO HUMAN ACCESS !NTENNAS USING PRINTED ARRAYS USE INTEGRAL 
 'RUMMAN #ORPORATION  . £Ç°Ón  2!$!2 (!.$"//+  3HADOWS 4HE SIMPLEST METHOD OF MEASURING OBJECT HEIGHT IS TO OBSERVE THE LENGTH  ,SHADOW OF THE SHADOW OF THE OBJECT CAST BY THE 3!2 AND CALCULATE THE OBJECT HEIGHT  H  FROM THE KNOWN 3!2 ALTITUDE ( AND GROUND RANGE 2G   H,( 2G SHADOW    4HIS EXPRESSION ASSUMES FLAT 
 Since this is not a sun-synchronous orbit and  since the antenna pattern (to first order) is symmetric, the spacecraft may be rotated  about the radar’s line-of-sight to help sustain near-full illumination of the two solar  panel arrays in all sun-orbit plane configurations. Radar data are recorded in a 256 Gbit  solid-state unit following 6-to-3 block-floating-point quantization. Spacecraft design  life is five years. 
 An example will illustrate the use of these curves. If you desire to hold  the sidelobe at a given point in space to less than 40 dB below the peak of the beam  with a probability of 0.99, draw a vertical line from −40 dB on the abscissa until it  intersects the 0.99 curve. From this intersection, draw a horizontal line and read the  value of MSSL, in this case −47 dB. 
 Ono, T. Kobayashi, and H. Oya, “Interim report of the Lunar Radar Sounder on-board  SELENE spacecraft,” in Proceedings, 35th COSPAR Assembly , Paris, France, pp. 
 TION FIXING  PARTICULARLY BY IDENTIFYING GROUND 
 Fortunately, solid-state module reliability has  proven to be even better than the MIL-HDBK-217 predictions. AN/FPS-115 (PA VE  PAWS), for example, has grown to 141,000 hours, which is 2.3 times the predicted  value. This includes the actual T/R module MTBF, along with the receiver transmit/ receiver (T/R) switches and phase shifters as well as the power amplifiers. 
 Equation (2.4a) may be rewritten as  (2.4b)  The noise figure may be interpreted, therefore, as a measure of the degradation of signal-to­ noise-ratio as the signal passes through the receiver.  Rearranging Eq. (2.4h), the input signal may be expressed as  S-= kToB,J 11S0  I N  0 (2.5)  If the minimum detectable signal Smin is that value of S1 corresponding to the minimum ratio or  output (IF) signal-to-noise ratio (S0 IN okin necessary for detection, then  kT0B11F11(§o) . 
 BASED SUB 
 Digital pulse compression has distinct features that determine its acceptability  for a particular radar application. Digital matched filtering usually requires multiple  overlapped processing units for extended range coverage. The advantages of the digi - tal approach are that long-duration waveforms present no problem, the results are  extremely stable under a wide variety of operating conditions, and the same implemen - tation could be used to handle multiple waveform types. 
 25.9 SPECIAL TECHNIQUES, PROBLEMS, AND REQUIREMENTS Pulse Chasing.4'-1-73'126-127'129 The concept of pulse chasing has been proposed as a means to reduce the complexity and cost of multibeam bistatic . receivers, which are one solution to the beam scan-on-scan problem. The sim- plest pulse-chasing concept replaces the multibeam receive system (n beams, re- ceivers, and signal processors) with a single beam, receiver, and signal proces- sor. 
 SCALE COMPOSITE SURFACE MODEL FOR THE OCEAN  WAVE 
 NIQUES v IN TH #ONF ON 2ADAR -ETEOROL  !-3  -ONTREAL    PP n  " ' ,AIRD  h/N AMBIGUITY RESOLUTION BY RANDOM PHASE PROCESSING v IN  TH #ONF 2ADAR  -ETEOROL  "OSTON  !-3    P   - 3ACHIDANANDA AND $ 3 :RNIC  h3YSTEMATIC PHASE CODES FOR RESOLVING RANGE OVERLAID SIGNALS  IN A DOPPLER WEATHER RADAR v * !TMOS /CEANIC 4ECHNOL   VOL   PP n     * 0IRTTILÅ AND - ,EHTINEN  h3OLVING THE RANGE 
 A phase-coded waveform that employs two phases is  called binary , or biphase , coding. A binary phase-coded waveform is constant  in magnitude with two phase values, 0 ° or 180 °. The binary code consists of a  sequence of either 0s and 1s or +1s and −1s. 
 The latter type of  feed requires a rotary joint. The nutating feed requires a flexible joint. If the antenna is small, it  may be easier to rotate the dish, which is offset, rather than the feed, thus avoiding the problem  of a rotary or flexible RF joint in the feed. 
 An ionospheric electron density model complex  enough to enable adequate sounding interpretation is required. Ionospheric or transmis - sion path statistical climatologies and forecasts are necessary for radar design and for  development of site-specific models. In addition, other users in the HF spectrum must be  observed continuously and operating frequencies selected to avoid interference. 
 V.. and J. H. 
 DRIVING 
 , vol. 36, pp. 125–142, 1998. 
 Furthermore, the sidelobes of both the sum and the difference patterns must be low.  The antenna must be capable of the desired bandwidth, and the patterns must have the desired  polarization characteristics. It is not surprising that the achievement of all these properties  cannot always be fully satisfied simultaneously. 
 This strategy reduces the impact of off-nadir  clutter arising from sources in the along-track direction. The technique improves the  subclutter visibility by 10 dB or more. The radar’s mass and input power are 17 kg and  64 W. 
 VI but this is not expected and likely to re ﬂect the poor performance of the prototype radar. Figure 7.7. Pfaversus range for a ﬁxed threshold; (a) sea state 3; solid line upwind, dashed line downwind; (b) sea state 3 upwind, solid line 1000 ft, dashed line 3000 ft.Airborne Maritime Surveillance Radar, Volume 1 7-12. 
 SION  WHICH IS MORE ECONOMICAL WHEN IT IS APPLICABLE !NALOG $OWNCONVERSION AND 3AMPLING  4HE GENERAL APPROACH TO DIGITAL DOWN 
 They must be properly taken into account, however, since they can have a major  impact on performance. Further discussion of the effects of propagation on radar is given in  Chap. 12. 
 SEARCH RADAR AND SMALL MISSILE  TARGETCLUTTER 
 An important ECCM tactic is to engage hostile jammers with  /101111•-011-jam (IIOJ) missile guidance. If the jammer is radiating, HOJ is generally a better  guidance technique than is radar guidance. Stand-olT jammers are also subject to direct attack  hy interceptor aircraft. 
 Responses at vertical incidence frequently cause trouble, for vertical-incidence signals are usually fairly strong. Thus the antenna pattern must be accurately known and taken into account in the data analysis. A pattern with strong minor lobes may be simply inadmissible. 
 The impedance ofthe driving source should besmall compared toR. InFig. 13.18b, asteep wavefront sets upashocked oscillation which is quickly damped out byRsothat essentially only one pulse isproduced. 
 CLUTTER CANCELLA 
 Cahlander: Radar Ground-Clutter Shields. Proc. I£££. 
 This dependence is the basis for the design of lenses and reflectors at radar wave- lengths as well as optical wavelengths. The variation of the refractive index of the water molecule with wavelength is responsible for the rainbow, the result of two refractions near the front of a spherical water droplet and a single internal reflec- tion from the rear. Secondary and tertiary rainbows are due to double and triple internal reflections. 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 a two-parameter (mean and variance) threshold or adapt a one-parameter threshold  on a sector basis. However, these rules should serve only as a general guideline. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation.  THE PROPAGATION FACTOR, FP, IN THE RADAR EQUATION  26.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 The propagation factor is a desirable quantity since it is an identifiable parameter in  most radar equations. 
 TRACKING ALGORITHMS CAN OPERATE IN MORE AMBIGUOUS SITUATIONS WHERE  THE DENSITY OF FALSE ALARMS   K  IS COMPARABLE TO OR GREATER THAN  K & OR K0  5NDER THESE  AMBIGUOUS CIRCUMSTANCES  THE FORWARD TRACKER WILL HAVE MULTIPLE DETECTIONS IN A  TRACK FORMATION OR PROMOTION GATE AND WILL REQUIRE MULTIPLE HYPOTHESIS TO RELIABLY  FORM TRACKS 4HE DESIGN OF THE TRACK FORMATION PROCESS AND THE AUTOMATIC DETECTION PROCESS  SHOULD BE CONSIDERED TOGETHER ! LONGER TIME ALLOWED FOR TRACK FORMATION HIGHER  -.  ALLOWS THE RADAR DETECTION PROCESS TO USE LOWER DETECTION THRESHOLDS  RESULT 
 This is a very challenging system engineering task.  Exhaustive mathematical assurance and system testing is required, which is completely  different from current commercial personal computer practice. A notional MFAR integrated core processing complex with its corresponding inter - faces similar to that shown in Figure 5.3 is shown in Figure 5.5, where there are  multiple redundant processing arrays that contain standardized modules connected in  a non-blocking switched network. 
 10.15. The rotating cylindrical sheath isdistorted (for aneight-oscillator magnetron) into asmaller cylinder with four spoke-like ridges running parallel toitsaxis. This space charge configuration rotates with anangular velocity which keeps itinstep with the alternating r-fcharges onthe anode segments, and theends ofthese spokes maybe thought ofasbrushing bytheends ofthe. 
 LaGrone, “Radar reflections from insects in the lower  atmosphere,” IEEE Trans ., vol. AP-14, pp. 224–227, March 1966. 
 Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar.  GROUND PENETRATING RADAR  21.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 where  Pt = transmitted power in watts  Pr = received power in watts  A = antenna gain  G = antenna effective aperture  R  = range in meters  a = target radar cross section  k = calibration coefficient The cumulative losses include the transmission coefficients into the ground; the  spreading losses describe the R–4 losses for a target of 1 m2; and the attenuation  losses are for a soil with a er of 9 and tan d  of 0.1. Fixed losses include the trans - mission losses into the soil and the effective radar cross section of the target, which  comprises its true radar cross section and reflection loss from the target. 
 However, s″c(t) can be significantly larger  and degrades the overall value of sc(t) to –40 dB. The value of sa(t) is determined by  any local inhomogeneities in the soil or by any covering material whether of mineral or  vegetable origin. There is unfortunately little that can be done to predict variations in  s″c(t), and it is not amenable to treatment by many processing algorithms. 
 Interest in millimeter radar has been mainly because of its challenges as a frontier  to be explored and put to productive use. Its good features are that it is a great place for  employing wide bandwidth signals (there is plenty of spectrum space); radars can have  high range-resolution and narrow beamwidths with small antennas; hostile electronic  countermeasures to military radars are difficult to employ; and it is easier to have  ch01.indd   17 11/30/07   4:34:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 When the edge taper is low, virtually all the power strikes the reflector  and the loss is insignificant. As taper decreases, there is more spillover, and feed power  misses the reflector, increasing the loss. On the other hand, with too much taper, the  taper efficiency is poor because the reflector is under illuminated. 
 SEC.2.13] THEROUND EARTH 53 only this difference issmall compared with k,the surface should reflect asthough itwere optically smooth. But M<Aimplies h<A/t), and if 0issmall, bumps which areactually large compared tokcanbetolerated. Something like this may occur insome circumstances over land. 
 47, pp. 821-828, May,  1959.  42. 
 Preist: Calculated Spectra of Distorted Gaussian Pulses, Microwave J., pp. 70-75, April 1965. 47. 
 or other hydrorneteors may be represented as a large number  of indeperident scatterers of cross section 0, located within the radar resolution cell. Let ai  denote the average total backscatter cross section of tlie particles per unit of volume. Tlie  iridicated summation of ni is carried out over the unit volume. 
 For  small phase errors, the amplitude of the resultant difference is 2A sin A¢/2 ::::: A A¢. Therefore  the limitation on the improvement. fa~tor· due_ to oscillator instability is  .. 
  
 J. P.: Electromagnetic Compatibility, chap. 29 of" Radar Handbook," McGraw-Hill t3ook  Company. 
 E. Antoniak, “A practical distribution-free detection procedure for multiple- range-bin radars,” IEEE Trans ., vol. AES-6, pp. 
 4.1] RANGE, PRF,ANDSPEED OFSCAN 119 chapters. This number will bedenoted byN-and defined, where exact specification isrequired, bytherelation (1) InEq. (1), v,isthepulse-repetition frequent y,eisthewidth inradians oftheradar beam, between half-gain points asusual, and u~istheangular velocity ofscanning inradians per second. 
 Elbaum: First-Order Statistics of a Non-Rayleigh Fading Signal and Its Detection,  Proc. IEEE, vol. 66, pp. 
 A rosette constellation of SBR satellites at an orbital altitude of 5600 nmi (10,371 km) in a 14/14/12 Walker orbit23 inclined at 49.4° provides continuous worldwide visibility by at least two satellites simultaneously. (One satellite is deployed in each of 14 equally spaced orbit planes.) Each satellite provides radar coverage between grazing angles from 3 to 70°. The major subsystems in the satellite include (1) radar, (2) communications, (3) guidance and control, and (4) electrical power subsystems. 
 These instructions included the need to check the local oscillator tuning every halfhour. When convenient, tuning was undertaken by stopping the scanner on a large target at 15 –20 miles range and observing the return on the height tube, with gain reduced to ensure that the return was not saturating. 3.7 Conclusions The introduction of centimetric ASV was a major countermeasure to the use of theMetox radar warning receivers on U-boats. 
 Choosing A = −13 dB   (a reasonable value for microwave frequencies) gives a fairly good match to the verti - cally polarized returns over a wide range of grazing angles. The facet  model, expressed  FIGURE 15.21  Comparison of several ad hoc feature models with NRL 4FR data  (data the same as shown in Figure 15.19) ch15.indd   33 12/15/07   6:17:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Figure 9.38 shows anearly type ofretractable airborne radome mounted onaB-29. The radome isacylinder 3% in.indiameter and extending about 33in.when unretracted. While the shape isideal electrically, itseffect onthespeed oftheaircraft ismost objectionable. 
 SEC.15.5] where N.= “r= e= ~=597 CHOICE OF PULSE LENGTH thenumber ofpulses perscan onthetarget, pulse recurrence frequency, azimuth beamwidth indegrees between half-power points, and scan rate indegrees persecond, weobtain therelation J-Sti, . “G,” From thepreceding section wehave(2) (3) where 7isthepulse length. From Eqs. 
 Lucero Mk. II TR 3505 used in ASV.X is shown in ﬁgure 6.2.I n 1944 Lucero II, TR 3566, was installed in ASV Mk. VI, with a 45 Mc/s IF andcovering 171 –238 Mc/s. 
 The  tracking bandwidth in some systems might be made variable or even adaptive to conform  automatically to the target conditions.  Another restriction on the tracking bandwidth is that it should be small compared to the  lowest natural resonant frequency of the antenna and servo system including the structure  foundation, in order to prevent the system from oscillating at the resonant frequency. The  shaded region in Fig. 
 Under ideal cir- cumstances (use ofentire interval between pulses, PRF consistent with Limitofscan bl~/ /’ \ \ /’ / ~j}~ / /\c / A\ /Radarbeam,~‘ ,~,!\~1, / / ~~\ I / /’//’Ak~T 2 ></ Pulsepacket n~ FIG. 42.-Analysis into pulse packets oftheregion scanned. Note that thepulse- packet, which defines a~olume from which echoes arereceix,ed simultaneously, isonlyhalf aslong astheoutgoing wave train. 
 9. Dodds, W. J., T. 
 13.1). Aprecision variable delay and afixed delay arecombined tofurnish a delayed trigger and aprecision range marker asdescribed inconnection with Fig. 13.39. 
     * ' 0ROAKIS AND $ ' -ANOLAKIS   $IGITAL 3IGNAL 0ROCESSING   ND %D  .EW 9ORK -ACMILLAN     % " (OGENAUER  h!N ECONOMICAL CLASS OF DIGITAL &ILTERS FOR DECIMATION AND INTERPOLATION v  )%%%  4RANSACTIONS ON !COUSTICS  3PEECH AND 3IGNAL 0ROCESSING  VOL !330 
 P. Molinie, J. Munoz, P. 
 If a large range is required of  a surveillance radar, the radar must have the necessary value of the product PavAe.  For this reason, a common measure of the capability of a surveillance radar is its  power-aperture product . Note that the radar frequency does not appear explicitly   in the surveillance radar equation. 
 Mitzner, however, sought the fields scattered in arbitrary directions, not just those  along the local Keller cones, and for this purpose he developed his incremental length  diffraction coefficient  (ILDC). Extending the example provided by Ufimtsev, he  devised a set of diffraction coefficients for arbitrary directions of incidence and scat - tering. Not unexpectedly, those coefficients are more complicated than the Xs and Ys  appearing in Eqs. 
 T    S    /F  THE ABOVE REQUIREMENTS  OSCILLATOR PHASE NOISE MAY DOMINATE (OWEVER  IN  SYSTEMS WITH LARGE BANDWIDTHS SHORT COMPRESSED PULSES   THE TIMING JITTER REQUIRE 
 The surface of the earth and the earth’s atmosphere can  drastically affect the propagation of electromagnetic waves and change the coverage and  capabilities of a radar. In the radar equation, these propagation effects are accounted for  by a factor F4 in the numerator of the radar equation, as discussed in Chapter 26. With  the above substituted into the simple form of the radar equation we get  RP G A n E n F kTF f S N Le i o n p smax( ) ( ) ( / )44 2 1 4=av σ π (1.5) In the above equation, it was assumed in its derivation that Bt ≈ 1, which is generally  applicable in radar. 
 Thustocstimate i-'-r-- 099 098 095·· 090- r;:a80 ~070 u ~060 LJ_050 o >-040. ~a30o .Deo20 Q. o10 005 002 001 -\0-5I [ o 510 15 20 Signaltonoiserollaperpulse-dB2530 Figure2.25Comparison ofdetection probabilities forRice,lognormal, chi-square withm=2(Swerling caseJ)andnonfluctuating targetmodelswithfJ=tohitsandfalse-alarm number "1=106•Ratioof dominant-to-background equalsunity(s=I)forRicedistribution. 
 The elements are assumed to be isotropic point sources radiating  uniformly in all directions with equal amplitude and phase. Although isotropic elements are  not realizable in practice, they are a useful concept in array theory, especially for the coniputa-  tion of radiation patterns. The effect of practical elements with nonisotropic patterns will be  considered later. 
 4RACK  OR 4RACK !CQUISITION  IS USED TO CONFIRM SEARCH TARGET DETEC 
 2 1 - 23, 1975, pp. 306--3 1 1.  48. 
 J., 28  Distortion, trapezium, 68  Dowding, Air Chief Marshal  first Baron, 22  Dummer, G. W. A., 29  Ecuo, speed of, 33  FEEDERS, 56 ef seq. 
 Γ1,1(ω1,ω2;ρn−ρm)=/angbracketleftexp{j2[φ1(ω1,ρn)−φ2(ω2,ρm)]}/angbracketright ≈exp/parenleftBig −2·/angbracketleftBig [φ1(ω1,ρn)−φ2(ω2,ρm)]2/angbracketrightBig/parenrightBig =Rφ(ω1,ω1;0)+Rφ(ω2,ω2;0)−2Rφ(ω1.ω2;Δx)(8) where Rφ(ωn,ωm;Δx)is the auto-correlation function (ACF) of the scintillation phase which is determined by the frequency separation ( ω1and ω2) and the 1-D IPP spatial separation (Δx=/bardblρm−ρn/bardbl). The ACF in Equation ( 8) is derived from the inverse Fourier transform of the power spectral density (PSD) function of the scintillation phase. In this paper, the Rino power law spectrum [ 29] is applied to simulate the scintillation phase screen and the ACF based on Rino’s spectrum can be expressed as Rφ(ω1,ω2;Δx)=r2 eλ1λ2CsLsecθnsecθmcosθi·G/vextendsingle/vextendsingle/vextendsingle/vextendsingleΔx 2q0/vextendsingle/vextendsingle/vextendsingle/vextendsinglev−1/2Kv−1/2(q0Δx) 2π·Γ0(v+1/2)(9) CsL=CkL/parenleftbigg2π 1000/parenrightbiggp+1 (10) where Gis the gain factor, Kε(·)is the modiﬁed Bessel function and Γ0(·)is the gamma function, both CsLand CkLare the symbols of scintillation strength and p=2vis the phase spectral index, q0=2π/L0is the wavenumber corresponding to the outer scales, θnand θmare the ionospheric incident angle of beam center at different sampling points. 
 81, no. 12. pp. 
 The theoretical development of signal estimator statistics is found in Denenberg, Serafin, and Peach42 for the FFT technique. Doviak and Zrnic11 cover the subject quite completely. Following are some useful expressions for the mean square error of mean power and mean velocity estimates. 
 CONTINUOUS BEAM SCAN CAN BE GENERATED WITH THE REQUIRED RATES AND RATE CHANGES  "ECAUSE OF PULSE PROPAGATION DELAYS FROM THE TARGET TO THE RECEIVER  THE POINTING  ANGLE OF THE RECEIVE BEAM  P2 MUST LAG THE ACTUAL PULSE POSITION &OR AN INSTANTANEOUS  PULSE POSITION THAT GENERATES A BISTATIC ANGLE  A   P2   P4  
 LOADING FORCES AND THERMAL GRADIENTS 4HE SECOND EXAMPLE IS A SPACE 
 The height at which M reaches a minimum is called  the evaporation duct height , as illustrated in Figure 26.6. Evaporation ducts exist over the ocean, to some degree, almost all the time. The  duct height varies from a meter or two in northern latitudes during winter nights to as  much as 40 meters in equatorial latitudes during summer days. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.52  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 Diode phase shifters have the advantage of being small and light in weight (except  for high-power devices). They are suitable for stripline, microstrip, and monolithic  configurations. 
 The several curves each correspond to a specific wind speed. In general, upwind  and downwind aspects provide stronger backscatter than cross-wind, and the upwind  aspect usually is a bit stronger than downwind. Wind vector data have been collected  by airborne scatterometers flying in circles (literally!) over instrumented test sites.122  There have been many attempts over the years to converge on a suitable mathemati - cal model for this behavior, with reasonable success.123 There are several vector wind  retrieval methods in current use, including CMOD-4 and a neural network model. 
 34!4% 42!.3-)44%23   ££°Î L &LEXIBILITY CAN BE REALIZED ! MODULE WITH BOTH TRANSMIT AND RECEIVE PATH AMPLIFIERS  42 MODULE  CAN BE ASSOCIATED WITH EVERY ANTENNA ELEMENT IN PHASED ARRAY SYS 
  &)'52%  3URFACE 
 Pucel (ed.), Monolithic Microwave Integrated Circuits , New York: IEEE Press, 1985.  97. J. 
 Radar, Sonar, and Navigation ,  vol. 145, pp. 173–180, June 1998. 
 ©2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). 
 4 
 ON 
 Challenges of Production Testing   Production testing involves  verification that each  manufactured product  meets its specifications. Test tasks  include tu ning and calibrating assemblies, along with the  compensation and calibration  of analog modules, linearizers,  and amplifier components. Results must be accura te and  repeatable to assure  the final product will function as  intended. 
 An array of spiral elements makes a simple scanning antenna. It is  primarily w;eful in those applications where a broadband element is required and the power is  not too high. The entire assembly, including the spiral radiators and feed networks, but  possibly excluding the rotary joint, can be manufactured with printed circuit techniques. 
 Figure 2.10 is a plot of the backscatter cross section of a long thin rod as a function of  aspect. 26 The rod is 39.t long and .t/4 in diameter, ~nd is made of silver. If the rod were of steel  instead of silver, the first maximum would be about 5 dB below that shown. 
 STATE AMPLIFIERS BASED ON A HIERARCHY OF MODULES  STARTING WITH ELEMENTAL AMPLI 
 659 16.16 The Coherent Oscillator 662 16.17 The Receiver ..... ... .. 
 4. Strallon. J. 
 Therefore the  majority of the cooling required in the klystron is at the collector. Power is extracted from  the output cavity and delivered to the load by a coupling loop (as shown in Fig. 6.9) for  low-power tubes, or by waveguide in high-power tubes. 
 10.4 DETECTION CRITERIA J  The detection of weak signals in the presence of noise is equivalent to deciding whether the  receiver output is due to noise alone or to signal-plus-noise. This is the type of decision  probably made (subconsciously) by a human operator on the basis of the information present  at the radar indicator. When the detection process is carried out automatically by electronic  means without the aid of an operator, the detection criterion cannot be left to chance and must  be carefully specified and built into the decision-making device by the radar designer. 
 Examples of HFSWR system performance model - ing160,162 generally follow the precepts described in Section 20.12. The main difference  here is the availability of path-loss descriptors such as those shown in Figure 20.40.  For example, consider a radar at 5 MHz with an average power of 10 kW (40 dBW), a  transmit-receive antenna gain product of 15 dB, and a target at 100 nmi with an RCS  of 20 dBsm; then the received power is  P dBWr= + + − = − 401520222 147   By using the January nighttime noise as given in Figure 20.19 b,  SNR P dBr= − = − + = N 147 153 6   and if 10 s coherent processing time is used,  SNR dB =16   As noted earlier, propagation loss accelerates rapidly with distance, especially at  higher frequencies, while atmospheric and surface roughness effects will accumu - late and contamination of the surface wave return with echoes received via skywave  paths will become increasingly severe, so quantitative performance predictions at long  ranges, beyond ~200 km, should be treated with caution. 
 ·. '·-/J_ I  l' ! •, I I  '-/. 30° " r,  Ronqe, nmi  (b) vertical polarization  Figure 12.4 {c0111i1111ed) PROPMii\TION OF Ri\Oi\R WA YES 447  0 5°  earth. 
 Further research may focus on the real-time implementation of the EMAM onboard. Author Contributions: Z.Z., Y.L., and Y.W. designed the study. 
 600 159 Choice ofWavelength. ,604 15.10 Components Design 606 15.11 hfodifications and Additions, 609. CONTENTS xvii DESIGN OFALIGHTWEIGHT AIRBORNE RADAR FOR NAVI~ATION 611 15.12 Design Objectives and Limitations. 
 1968.  rr. 64 69. 
 VENTIONAL PHASED ARRAY RADAR THAT DOES NOT EMPLOY THE ACTIVE APERTURE &OR ACTIVE APERTURE PHASED ARRAY RADARS  IT IS LIKELY THAT THE SOLID 
 Along­ persistence screensuchastheP19isappropriate ,forPPI presentations wheretheframetimes areontheorderofseveralseconds. Ontheotherhand,wherenopersistence isneeded,aswhen theframetimeislessthantheresponse timeoftheeye(0.1sorless),aPIphosphor mighthe used.ThePIphosphor iscommonly foundinmostA-scope presentations. Inordertoachievelongdecaytimesatwo-layer, orcascade, screenissometimes used,as intheP7ortheP14.Thefirstphosphor layeremitsanintenselightofshortduration when excitedbytheelectron beam.Thelightfromtheinitialflashexcitesthesecondlayer,emitting a persistent luminescence. 
 The main reflec - tion caused by the air-ground interface can clearly be seen coming back toward the  antenna system. In addition, a weaker reflection coming from the buried object is  starting to form and follows the air-ground interface reflection in time. This is a typical  time-domain characteristic of standoff GPR system. 
 SUMPTION HARDWARE !DAPTIVE !RRAYS  !N ADAPTIVE ARRAY &IGURE   IS A COLLECTION OF . ANTENNAS  WITH THEIR OWN RECEIVERS 28  AND !$#  FEEDING A WEIGHTING AND SUMMING NETWORK  WITH AUTOMATIC SIGNAL 
 TO 
 The variation inmagnetron efficiency issimilartothatofthevariation withpower. Thechangeintheoscillator frequency produced byachangeintheanodecurrentfora fixedloadiscalledthepushingfigure.Aplotoffrequency vs.current, asinFig.6.6c,iscalled thepushingcharacteristic andtheslopeofthecurveisthepushing figure.Thelowerthevalue ofthepushing figure,thebetterthefrequency stability. Thecoaxialmagnetron hasalower pushing figurethanaconventional magnetron becauseofthestabilizing effect(highQ)ofit's relatively largecoaxialTEo11cavity.Pushing effectsaremoreseriouswithlongerpulsessince theirspectraarenarrow. 
 14.3. The discussion of the servo constants will be postponed until the end of this section. The most sensitive technique for adjusting the quadrature detector is to introduce intentional AM and null this by adjustment of the phase shifter. 
 A less restrictive brightness constraint was chosen to address the intensity changes in SAR images. In Reference [ 31], it is proposed that the brightness constancy constraint can be replaced with a more general constraint that allows a linear transformation between the pixel brightness values. This way, the brightness change can be non-zero, or: dI dt/negationslash=0. 
 %##- v  )%%% 4RANS  VOL !%3n  NO    PP n  *ULY    3 , *OHNSTON ED    2ADAR %LECTRONIC #OUNTER 
 103- 107, 1977.  94. Fit zmaurice. 
 45. Ramsay, J. F.: Fourier Transforms in Aerial Theory, Marconi Rev., vol. 
 MODE OPERATION IS ALSO REQUIRED IF A COMBINATION OF -4) OPERATION AND FREQUENCY AGILITY IS DESIRED )F A BIMODAL CLUTTER SITUATION IS CAUSED BY THE SIMULTANEOUS PRESENCE OF RETURNS FROM  LAND CLUTTER AND WEATHER OR CHAFF  AN ADAPTIVE -4) CAN BE IMPLEMENTED FOLLOWING A FIXED 
 A further four squadrons were used for photo-reconnaissance, six for air/sea rescue and six for meteorological operations, representing a further establishment of 297 aircraft, of which 112 wereavailable for operations. The deployment of different ASV systems in Coastal Command reconnaissance aircraft at the end of WWII was as follows [ 1]: ASV Mk. II LRASV and SRASV on Halifaxes, Fortresses, Warwicks I, Hudsons and Sea Otters of meteorological and air/sea rescue squadrons; ASV Mk. 
 WATER %- PROPAGATION  IT WARRANTS A DETAILED DISCUSSION 4HIS DISCUSSION APPEARS IN ITS OWN SECTION BELOW 3URFACE 
 Sensors 2019 ,19, 2161 scintillation effect, which also consists with the aforementioned analysis. Furthermore, the ionospheric coherent length is applied to analyze the decorrelation of P-band sliding spotlight mode, which is deﬁned as the spatial separation ΔxwhenΓ(ω0;Δx)≤0.707. The imaging degeneration need to be considered when the IPL is longer than the ionospheric coherent length. 
 Remote Sens. Lett. 2014 ,11, 828–832. 
  
 86. Kalafus. R. 
 17.1  Pulse Doppler Spectrum  ....................................  17.2 Ambiguities and PRF Selection  ..........................  17.5  Basic Configuration  ............................................ 
 On the other hand, if they are separated too far, there isn't sufficient signal-to-noise ratio in one of the beams for accuracy. It follows that there is a beam step size that optimizes accuracy by maximizing sensitivity and minimizing errors. This is clearly illustrated in Fig. 
 Although there has been much development work in solid-state phased arrays with each  element fed by its own integrated module, this approach usually results in a costly and  complex system. This has tended, in the past, to weigh against the widespread usc of such  phased-array radars when the number of elements is large.  The combining of the power from a large number of individual solid-state devices is  attractive when using an array antenna since the power is "combined in space," rattier tliatl by  a lossy microwave network. 
 T able 2. ERS radiometric parameters. Parameter Units Carrier Frequency fc=5.300 GHz Chirp Duration Tc=37.12 μs Chirp Bandwidth Bch=15.50829 MHz Sampling Frequency fs=18.962 MHz Figure 8. 
 Therange strobe would then be set using the height tube indicator and the auto –manual switch was set to auto. The target would then be tracked in range and azimuth. In order to prevent saturation of the IF ampli ﬁer, which would prevent tracking, Figure 4.12. 
 TAGE IS THAT THIS GAIN CALCULATION ASSUMES LINEAR TARGET MOTION WITH RANDOM PERTURBA 
 240–249, 1997. 62. Y . 
 The above are sometimes called  active methods for generating waveforms.  The linear FM waveform may also be generated by passive methods such as by exciting a  dispersive delay line with an impulse. The frequency-response function of the di/persive delay  line used for generating the transmitted waveform is the conjugate of that of the pulse­ compression filter. 
 BEAM ANGULAR INTERVAL ;n  = DETAILS ON THE NUMERICAL PARAMETERS USED IN THE STUDY CASE ARE IN THE  REFERENCE  )T IS NOTED THAT 04" IS NEGLIGIBLE FOR &     D"  WHILE 0" q  !FTER A CAREFUL PERFORMANCE EVALUATION OF THE SYSTEM DEPICTED IN &IGURE   IT  MIGHT BE NECESSARY TO ALWAYS RESORT TO EITHER SPATIAL OR FREQUENCY DIVERSITY TO IMPROVE THE 3," PERFORMANCE 4HE SELECTION OF ONE OF THE TWO DIVERSITY TECHNIQUES DEPENDS ON OVERALL SYSTEM CONSIDERATIONS RELATED TO THE IMPACT OF ADDING MORE AUXILIARIES ANDOR RADIATING  WITH THE RADAR  PROPER CARRIER FREQUENCIES &URTHERMORE  IF COMPACT AND HIGH 
 A. Berry and M. E. 
 SUREMENTS WITH THE 3KYLAB RADIOMETER 
 2'0/ 4!2'%4 ./,/34 4!2'%43 4S S  4AVE S  0- 7 0/3%22 M 6%,%22 MS       n         4!",%  3IMULATION 2ESULTS 7ITH 2'0/ AND ! 
 SIGHT OR SPACEWAVE PROPAGATION IS APPROPRIATE  SUCH AS MEASUREMENT OF THE (& 2#3 OF AEROSPACE VEHICLES &URTHERMORE  IN MANY INSTANCES  BISTATIC CONFIGURATIONS CAN BE EMPLOYED  WITH THE POSSIBILITY OF USING DIFFERENT PROPAGATION MECHANISMS FOR TRANS 
 Telecom. Inf. Adm. 
 !K & EK N7KPKHN N Nc c £    WHERE   7K D EH #N IK N    ;   = 
 Knott, “Radar observables,” in Tactical Missile Aerodynamics: General Topics , V ol. 141,  M. J. 
 2.29 as a function of the collapsing ratio  (m + 11)!11. The difference between the two cases can be large. As the number of hits II increases,  the difference becomes smaller. 
 lts value is zero at L\ TR = 0, and its even-order derivatives are zero.  For small values of L\ TR, the output will be directly proportional to L\ TR. (Thus it is similar to  · the angle-error detector of a monopulse tracking radar.)  The ratio or the root mean-square noise voltage (n;)112 to the slope M of the output  1(L\ TR) evaluated at L\ TR = 0 will be taken as a measure of the rms error in time measure­ ment. 
 Ort, E. Malaret, M. Robinson,   and E. 
 Many GPR  systems operate in a region where the wavelengths radiated are greater or in the same  order of magnitude as the target dimensions. Thus, GPR operates between the Rayleigh  region and Mie or resonance region of the target dimensions. This is very different  from conventional radar systems where the target dimensions are much larger than the  wavelength of the incident radiation, i.e., the optical region. 
 (10.26) we get  f [y(t) -s;(t)]2 dt = f y2(t) dt -2 f y(t)s1(t) dt + f sr(t) dt ( 10.27)  Upon reception, the waveform y(t) is known, so that the first integral on the right-hand side of  the equation is constant and can be absorbed in the constant k. The last integral is the energy E  contained within the signal si(t) and also is a constant. The second integral is not a constant. 
 MUM DOPPLER FILTER WILL HAVE WEIGHTS GIVEN BY  WS# /04  
  P %QUIVALENTLY  THE COMPLEX ENVELOPE SPECTRUM BELOW ZERO  FREQUENCY  CAN BE SHIFTED UP TO ZERO FREQUENCY BY MULTIPLICATION WITH THE TIME SERIES  UI EJI  P 4HIS RESULTS IN THE SPECTRUM SHOWN WHERE THE DESIRED SPECTRUM  CORRE 
 ONLY  PRECISION RANGE INSTRUMENTATION SYSTEMS WERE DEVELOPED IN THE 53 AFTER 77))  "OTH BEACON 
 Guinard. N. W., J. 
       *')  ' (*' # $) $*')  ' (*' # $) %,$ *+ ''  )  %')& ) $) '+" %$ & ) $) '+"   $ *+ ''  )    
 If the image is well-focused, the IC value of the image is large. IC deﬁnition is considered as the ratio of the standard deviation to the mean of the amplitude. The IC is written as follows [ 34]: IC(I)=/radicalbigg E/braceleftBig [I(k,n)−E{I(k,n)}]2/bracerightBig E{I(k,n)}(7) where Erepresents the spatial mean operator. 
 When a very complex system is to  be simulated, it is generally preferred to resort to several programs of limited com - plexity in lieu of a single bulky simulation. This approach corresponds to partitioning  the whole system into subsystems separately modeled in detail. From each partial  simulation, a limited number of relevant features are extracted and employed to build  a simplified model of the overall system. 
 In particu - lar, the LDMOS structure enables a short channel as a result of the lateral diffusion of  the p-type implant. The resulting short channel contributes to improved high frequency  response in spite of the lower mobility of silicon. The measured breakdown voltages  can be in excess of 100 V , so operation at higher voltages is possible, or conversely, a  higher level of margin in ruggedness can be achieved for a given operating voltage; the  latter is a key advantage for high-reliability power amplifier applications. 
 moist ai1 to p1odtH.:e a temperature inversion: i.e .. a11 increase.in temperature with  height. This results in a strong duct along the interface of the temperature inversion. 
 Omitting forthemoment allquestions ofamplitude versus frequency modulation, and allproblems ofexternal interference, the choice ofa data-transmission system involves three intricately related questions: (1)how toavoid interference with the video and trigger signals and mutual interference among the various data signals; (2)whether touse c-w orpulse methods; (3)which geometrical quantities among those descriptive ofthe scanner motion can best bechosen fortransmission. Since the video signals contain frequencies from nearly zero uptoa few megacycles per second itisnot feasible toseparate scanner data signals and radar echo signals on‘abasis oftheir frequency components. This leaves the two alternatives oftime-sharing within the radar pulse cycle, ortheuseofone ormore subcarriers. 
 HALF OF THE  PEAK SIGNAL POWER AND THE MATCHED 
 SHIP MOVEMENTS )N RELATIVE MOTION 
 Generally, long range  is easier to achieve at the lower frequencies because it is easier to obtain high-power  transmitters and physically large antennas at the lower frequencies. On the other  hand, at the higher radar frequencies, it is easier to achieve accurate measurements of  range and location because the higher frequencies provide wider bandwidth (which  determines range accuracy and range resolution) as well as narrower beam antennas  for a given physical size antenna (which determines angle accuracy and angle resolu - tion). In the following, the applications usually found in the various radar bands are  briefly indicated. 
 Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar.  PULSE DOPPLER RADAR  4.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 Range Gating.  Range gating divides the time between transmit pulses into mul - tiple cells or range gates. 
 FED PARABOLOIDS v  )%%%  4RANS  VOL !0 
 White, W. D.: Circular Polarization C.uts Rain Clutter, Electronics, vol. 27, pp. 
 DIMENSIONAL PHASED ARRAY  THAT IS ELECTRONICALLY SCANNED IN  ELEVATION WHILE SLOWLY ROTATING IN AZIMUTH  )N THIS WAY  A FULL HEMISPHERIC VOLUME  CAN BE COVERED IN n MINUTES AND SMALLER SECTOR VOLUMES MAY BE COVERED IN LESS THAN  MINUTE  3EVERAL MILITARY RADARS AND AVIATION RADARS UTILIZE ELECTRONICALLY SCANNED  BEAMS BUT THE EXPENSE OF A FULLY CAPABLE SYSTEM HAS PREVENTED MORE THAN ONLY A FEW METEOROLOGICAL RADAR SYSTEMS FROM BEING DESIGNED AND BUILT   2APID 
 NOISE RATIO IS A RMS POWER RATIO MEASURED AT THE !$ CONVERTER ! PEAK POWER RATIO WOULD BE  D" HIGHER  &)'52%  $YNAMIC 
    
 Atmos. Ocean. TechnoL, vol. 
 FIGURE 13.36  Typical solid-state module ch13.indd   53 12/17/07   2:41:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 The functions may be programmed adaptively to the limit of one's capability to exercise effective auto- matic management and control. Phased array theory was studied intensively in the 1960s, bringing understand- ing. Technology advanced and led to a series of operational systems in the 1980s; many publications became available.4"15 In terms of performance improvement, ultralow sidelobes (less than —40 dB) were demonstrated first in the 1970s by Westinghouse Electric Corporation's AWACS (Airborne Warning and Control System) and brought about tight tolerances in construction and phase settings. 
 I. W.: Frequency-scanned Arrays, chap. 13 of" Radar Handbook," M. 
 Special tracking radar applications with nontypical  requirements could arrive at a different optimum beam offset. A major limitation of scanning and lobing radar is the susceptibility to target ampli - tude fluctuations that occur during the time the beam is moved from side to side or up  and down. It is also susceptible to false modulation on signals from countermeasures. 
 Another procedure for the  measurement of direction uses several receiving antennas, at which the phase difference of the r e- ceived signal is used for the direction finding.  Examples are mono -pulse Radar (section 11,1,1) and   interferometers, as used in astronomy.   4.4 Polarization Characteristics of the Target   The polarization of a target is rarely considered. 
 ASPECT 3EARCH HIGH 
 3.9). These figures also illustrate that, to provide good suppression of both forms of interference, the shape of the filter bandpass characteristic is even more important than its band- width. Rectangular bandpass or impulse responses should be avoided; the closer one approximates a gaussian filter, the better the skirts in both frequency and time domains. 
 inthe receiver, whether bydirect leakage orreflection from stationary objects, only output signals that have thesame periodicity; these output signals can theref ore beremoved byasequence ofinfinit e-attenuat ion filters tuned tofrequency zero and toallharmonics ofthe modulation frequency. Finally, wenote that this system will handle only one target. If more are present the precise behavior depends onthe type ofphase meter used and thebest that can bedone istochoose atype that meas- ures range tothat target which gives the most intense reflection. 
 The significant height , or peak-to-trough height of the one-third  highest waves, provides such a measure. It is denoted by H1/3 and is taken to be about  six times the spectral rms amplitude (see, e.g., Kinsman,20 Fig. 8.4-2). 
   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°ÎÎ THE SHIP FROM THE BOW AT  KM AND n  GRAZING 4HE BRIGHT SCATTERERS EXHIBIT CROSS  RANGE SIDELOBES  WHICH CAN BE PARTIALLY REDUCED BY SENSING LARGE RETURNS  THEN APPLY 
 2. M. I. 
 Asinallsuperheterodynes, tuning isaccomplished bycontrolling the frequency ofthelocal oscillator. Since theratio ofthebandwidth tothe carrier frequency isextremely small (ofthe order ofone part inafew thousand), the tuning iscritical. Some form ofautomatic frequency control isessential ifconstant manual tuning adjustments are tobe avoided. 
 TION AND MULTIPLE SPECTRA !-4) CLUTTER CANCELLATION , 
 This method has been little used inradar, however, partly because ofgeneral complications and partly be- cause when apentode isused inapositive saw-tooth gener- ator itisnecessary toprovide afloating screen-voltage supply. Figure 13.31 illustrates the use ofacathode follower to keep thevoltage drop across Rnearly constant. That part above the switch indi- cates threealternatives. 
 The simplest form ofindicator has range along the horizontal axis and Adonthe vertical Slantbzam videosignals Vytical.beam wdeosignals 102030405060 Rangemmiles-- FIG.627.-Simple V-beam indicator. Lines ofconstant height areshown,axis (Fig. 6.27). 
 THE 
   AND %.6)3!4  )F THE ALTIMETER IS NOT THE PRIMARY PAYLOAD  THEN  THE RESULTING MISSION AND ORBIT ARE LIKELY TO BE DETERMINED BY OTHER REQUIREMENTS  WHICH MAY COMPROMISE ALTIMETRY 4HE %UROPEAN 3PACE !GENCYS SATELLITE ALTIMETERS ON %23 
 These phase samples may define the baseband components of the  desired waveform, or they may define the waveform components on a low-frequency  carrier. If the waveform is on a carrier, the balanced modulator is not required, and the  filtered components would be added directly. The sample-and-hold circuit removes  the transients due to the nonzero transition time of the digital-to-analog (D/A) con - verter. 
 FIELD TUBES   BUT IN THE  COLLECTOR  SHOWN AT THE  RIGHT 
    
 ...,, ~150 Small freighter ........ 1.5 ?Jedium freighter ., 80 Large freighter ................ 160 Small submarine (surfaced). 
 99. R. K. 
 DETECTOR OUTPUTS  AND AT LONG RANGE  THE ECHO IS WEAK  ALLOWING RECEIVER NOISE TO CAUSE  ADDITIONAL RANDOM FLUC 
 3.Some form oflimiting must beprovided. The noise voltage at theoutput ofthedetector will beapproximately 2or3volts peak. Inorder that thenoise beclearly visible onthescreen, itmust be amplified sufficiently todrive the indicator tube over something like half itsallowable control-grid voltage swing. 
 M. Spetner: Two Statistical Models of Radar Return. I RE Trw1s .. 
 Arudi- mentary system using atwo-wire transmission line isshown inFig. 11.14. The high-power pulse from the magnetron breaks down the gap inthe ATR tube and thepower flows outtoward theantenna. 
 vol.2.no.4,pp.17-32,1975. 50.Murray, 1.P.:Electromagnetic Compatibility, chap.29of"RadarHandbook," McGraw-Hili Book Company, NewYork,1970. 51.Johnson, M.A.,andD.C.Stoner:ECCMfromtheRadarDesigner's Viewpoint, IEEEEledro70. 
 166. C. J. 
 The likelihood  ratio [Eq. (10.34) divided by (10.33)] is  L,(r,) = exp (-n a22 ) ;oi Io(av,) ~ 11. (10.35)  where A. 
 35. Fletcher, R. H., Jr., and D. 
 8:IOh). The drive wire is oriented for minimum RF  coupling. It is also important to have proper mechanical contact between the toroid and the  waveguide wall since an air gap can give rise to the generation of higher-orcier rnodes that cirri  result ill relatively large narrow-freqtrency-band, insertion-loss spikes. 
 Introduction The pulsars are rotating neutron stars formed due to the collapse of massive stars core. They are the densest form of matter in the Universe. During the collapse stage the preservation of angular momentum causes the star to “spin-up” to a rotation period of order 10ms, whereas the preservation of magnetic ﬂux drives the magnetic ﬁeld strength at the stellar surface up to 1012gauss or higher, with magnetic moments up to 1026gaus-m3. 
 Quill was the only American SBR whose data were optically recorded  onboard, eventually returned to Earth by ejected capsule, and then collected by an  airborne retrieval maneuver. TABLE 18.2  Synthetic Aperture Radars (Earth-viewing) Satellite/SAR URL Country Launch Res (m) Band Polarization Quill  1 USA 1964 (>100 m) X Seasat  2 USA 1978 25 L HH SIR A; B  3 USA 1981; ‘84 40; ∼25 L HH SIR C  4 USA; G, I 1994, ‘94 ∼30 L&C; X Various to quad; HH Kosmos 1870  5 USSR 1987 15–30 S HH Almaz  6 USSR 1991 15–30 S HH ERS-1  7 ESA 1991 25 C VV J-ERS-1  8 Japan 1992 30 L HH RADARSAT-1  9 Canada 1995 8, 25, 50, 100 C HH ERS-2 10 ESA 1995 25 C VV Priroda 11 Russia/Ukraine 1996 50 S, L HH, VV SRTM 12 USA; G, I 2000 ∼30 C, X HH, VV ENVISAT 13 ESA 2002 10, 30, 150,1000 C VV or HH, dual IGS-1B 14 Japan 2003 + 1, + X Multimode PALSAR 15 Japan 2006 2.5–100 L Various to Quad JianBing-5 16 China 2006 3–20 L Multi-polarimetric TerraSAR-X 17 Germany 2007 1, 3, 15 X Various RADARSAT-2 18 Canada 2007 1, 3, 25, 100 C Various to Quad COSMO 19 Italy 2007 1, 3, 25, 100 X Multi-polarimetric TecSAR 20 Israel 2007 1–8 X Multimode ch18.indd   6 12/19/07   5:13:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The optimal binary integrator is much better than the moving- . SAMPLE SIZE, n FIG. 8.8 Optimum values of PN as a function of the sample size n and the proba- bility of false alarm a; Ricean distribution with SIN = O dB per pulse. 
 The impedance ofa standard waveguide isdefined asunity, and resistive orreactive elements inserted inthe guide arecomputed relative tothe standard, rather than inohms. Atypical choke joint between pieces of~~aveguide isshown inFig. 11.10. 
 29-30.May1.1958.AFCRC-TR-58-145(1), ASTIADocument 152409. 61.Brown. R.M..Jr..andR.C.Dodson: Parasitic SpiralArrays,IREIntern.COIll·.Record,vol.8,pt.I. 
 METAL CAPACITORS   AND VIA 
 TO 
 The slit is displaced from the optical axis at the place where the offset frequency  focuses the real image. A recording film in the output plane P2, when moved with a speed  proportional to that of the vehicle carrying the radar, produces a map of the scene originally  viewed by the radar.  If amplitude weighting of the synthetic aperture is desired to reduce the sidelobes, a  shaded transparency with uniform phase thickness can he inserted adjacent to the data film in  plane P1•  Digital processing. 
 Responses due to moving  targets will differ from the zero-doppler response. If the matched filter is based only  on the zero-doppler response, an increase in the time sidelobes will result. Ultimately,  if the doppler shift becomes very large, the matched filter response will degrade. 
 WhenfJ=UIO°,the doppler frequency iszero;therefore movingtargetscannotbediscriminated onthebasisof }. +20 ka=20 enu+10 ka=.2.36,--'--I 1'[ -10- 140160180 6080100120 Scattering angle13.deg4020-20L-...i--~-----L---l_-L---L.--'--------'-_L--.J----'---'----'-",-----'--......J---L----' o Figure14.13Bistaticcrosssectionabofasphereasafunction ofthescattering anglefJandtwovaluesof ka=2rra(A.,whereaisthesphereradiusand).isthewavelength. SolidcurvesarefortheEplane(fJ measured intheplaneoftheEvector);dashedcurvesarefortheHplane(fJmeasured intheplaneoftheH vector,perpendicular totheEvector).65.69. 
 The monopulse tracking radar discussed in Chapter 9 is  a good example. The accuracy of an angle measurement depends on the electrical size  of the antenna ; i.e., the size of the antenna given in wavelengths. Size and Shape. 
 The frequency range of propeller modulation  depends upon the shaft-rotation speed and the number of propeller blades. It is usually in the  vicinity of 50 to 60 Hz for World War II aircraft engines. This could be a potential source of  difficulty in a CW radar since it might mask the target's doppler signal or it might cause an  erroneous measurement of doppler frequency. 
 On the other hand, the narrower beam  implies that the waveform is more sensitive to spacecraft attitude errors. AltiKa’s  500 MHz bandwidth leads to a pulse-limited footprint about 30% smaller than usual.  ch18.indd   36 12/19/07   5:14:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Ignoring the constant G,, Eq. (10.1) for the matched filter  may then be written as  and 4m(f) = -4df) + 2xfil (10.3b)  370INTRODUCTION TORADAR SYSTEMS receiverbandwidth 8shouldbeapproximately equaltothereciprocal ofthepulse width r.As weshallseelater,thisisareasonable approximation forpulseradarswithconventional superheterodyne receivers. Itisnotgenerally validforotherwaveforms, however, andis mentioned toillustrate inaqualitative manner theeffectofthereceiver characteristic on signal-to-noise ratio.Theexactspecification oftheoptimum receiver characteristic involves thefrequency-response function andtheshapeofthereceived waveform. 
 Nowadays, CNNs [ 23] are playing an important role in detection and recognition. One of the most remarkable results was its application in the ImageNet data set. The ImageNet dataset includes over 15 million images with 22,000 different categories. 
 (.-lfit,r Kic~~~r~~li.~~l)  <", ', 8.7 SIMULTANEOUS MULTIPLE BEAMS FROM ARRAY ANTENNAS \  One of the properties of the phased array is the ability to generate multiple independent beam:  simultaneously from a single aperture. In principle, an N-element array can generate N  independent beams. Multiple beams allow parallel operation and a higher data rate than can  be achieved from a single beam. 
 FILING RADAR   OR hWIND PROFILERv 7IND PROFILERS USUALLY TAKE THE FORM OF 6(& AND  5(& MULTIPLE FIXED 
 The cathode-ray tube (CRT) has been almost universally used as the radar display. There  are two basic cathode-ray tube displays. One is the deflection-modulated CRT, such as the  /\-scope, in which a target is indicated by the deflection of the electron beam. 
 For uniqueness the  sampling theorem must be fulfilled, meaning at minimum each half period of the Do p- pler oscill ation must be sample d.  € PRF =4⋅vmax λ0 (8.8)  The resolution is a result of the observation period, meaning of the number of the used sample  values NFFT of the Fourier transform.  € Δv=λ0⋅PRF 2NFFT (8.9)  One speaks about blind frequencies for the phase differences  between the transmitting and  receiving signal of  € ±n2π. 
 For nonsymmetrical  NLFM, excellent  time sidelobes if  there is adequate  NLFM phase coding,  a high TB product,  and sufficiently low  amplitude and phase  errors. Increasing  NLFM phase code  weighting introduces  increased radial  velocity sensitivity. Good time  sidelobes that are  determined by  coding.Better time sidelobes  than binary phase- coded waveforms. 
 Erratic behaviour of thyratron-type circuits is to be  expected above 15,000 cycles per second. ©  O HT. Fe  = OSynch. 
 ULAR TIME BUT MOST SHOULD  BE CONSIDERED  EVEN IF BRIEFLY  BY THE RADAR SYSTEM DESIGNER  WHEN TRYING TO DETERMINE A NEW RADAR SYSTEM DESIGN OR AN UPGRADE OF SOME EXISTING SYSTEM /PINIONS ABOUT THE UTILITY OF THE VARIOUS VACUUM TUBE TRANSMITTERS MENTIONED HERE WILL BE BRIEFLY GIVEN NEXT  WITH THE SUGGESTION TO THE READER TO KEEP IN MIND THAT CIRCUMSTANCES CAN CHANGE AND THESE OPINIONS CAN CHANGE AS WELL 4HESE OPINIONS ARE NOT hWRITTEN IN STONE v AND ARE NOT LIKELY TO BE UNIVERSALLY AGREED TO BY ALL THOSE WHO WORK IN RADAR "UT THAT IS THE NATURE OF ANY ENGINEERING ENDEAVOR "RIEF /PINIONS !BOUT THE 5TILITY OF 6ARIOUS 2ADAR 6ACUUM 4UBES  4HE TYPES  OF 2& POWER SOURCES ARE MENTIONED BELOW IN NO PARTICULAR ORDER 'RID 
 The average detectionranges against a surfaced submarine results are shown in table 2.4. Table 2.4. Average recorded detection ranges. 
 Some passive bistatic radars operate in this configuration, where  the floodlight transmitter is provided by a TV or FM broadcast station.49,50 A single receive beam can be used with a transmit antenna that is adaptively tapered  to flood only the angular region covered by the receive beam at a given look angle,  with the tapering such that the signal-to-noise ratio at the receiver is held constant at  all positions along the receive beam. This scheme is analogous to the monostatic air  surveillance radar using a cosecant-squared antenna pattern, where the echo is inde - pendent of range for a constant altitude target.15 It has the potential of restoring much  of the frame time and range performance, but incurs increased sidelobe clutter levels  and increased transmitter cost and complexity. An example is given in Willis.1 Noncooperative RF Environment. 
 2017 ,9, 1087. [ CrossRef ] 19. Ishimaru, A.; Kuga, Y.; Liu, J.; Kim, Y.; Freeman, T. 
 90. Shanks, H. E.: A Geometrical Optics Method of Pattern Synthesis for Linear Arrays, IRE Tra~ls.,  vol. 
 (From Masuko et al.,29 © by the American Geophysical Union.)AZIMUTH ANGLE (degrees) (a)AZIMUTH ANGLE (degrees) (b)VV POLARIZATION INCLUDING ANGLE :41-45°WINDSPEED : 7.5-7.9 m/sHHPOLARlZATIONINCLUDING ANGLE :41-45° WINDSPEED :7.5-7.9m/s . pendent on frequency, has a maximum of about +15 dB at zero wind speed (at least for the antenna beam widths and experimental configurations reported), and falls off gradually as the wind picks up. Scattering at high grazing angles is com- monly regarded as a form of specular scattering from tilted facets of the surface; so it is of interest to note that there appears to be a small range of angles in the neighborhood of 80° for which the cross section is almost completely independent of wind speed. 
 21.21  Three-Dimensional Spectrum  .............................  21.21  22. Space-Based Radar Systems and  Technology   .............................................................. 
 Locke, A. S.: "Guidance," pp. 402--408, D. 
 The width must be large enough to obtain a high azimuth resolution. However, if the width is too large, the RCS amplitude will be inaccurate because the sub-aperture method uses the mean value of RCS amplitudes in θwas the RCS amplitude in the central angle θ(k). The coherent complex image of each sub-aperture is obtained by using the back projection (BP) algorithm [ 21,22]. 
 Exceptaspermitted undertheUnitedStatesCopyright Actof1976,nopartofthispublication maybereproduced ordistributed in anyformorbyanymeans,orstoredinadatabaseorretrievalsystem, withoutthepriorwrittenpermission ofthepublisher. I 2 34 5 6 7 89 2 0 BJE9 8 76 54 ThisbookwassetinTimesRoman. TheeditorwasFrankJ.Cerra. 
 Basically, there are two approaches to solving this problem: (1) remove large returns from the calculation of the threshold,26"28 or (2) diminish the effects of large returns by either limiting or using log video. The technique that should be used is a function of the partic- ular radar system and its environment. Rickard and Dillard27 proposed a class of detectors DK, where the K largest samples are censored (removed) from the reference cells. 
 MON VALUES OF RANGE AND REFLECTION HEIGHT 4HE VERTICAL BEAMWIDTH NEEDS TO BE SUF 
 TO NOISE RATIO DETECTION  ILLUSTRATING THE EFFECTIVENESS OF THE ACTIVITY CONTROL USING THE SIGNAL 
 MODE OUTER  PEAKS (OWEVER  BECAUSE THE TWO MODES PROPAGATE AT DIFFERENT VELOCITIES  A POINT IS REACHED FARTHER DOWN THE DOUBLE 
 SEC, 1321] SPECIAL RECEIVING TECHNIQUES 553 valuable forcertain purposes, anticlutter measures leave much tobe desired inthesituation under discussion. The’’ Three-tone” lkfethod.-A simple but extremely effective method ofretaining detail onhigh-intensity echoes while still providing land-to- water contrast isillustratedin Fig. 13.54. 
 R. Burrows and S. S. 
 2AYLEIGH DENSITY  SUCH AS THE CHI 
 The optimum filter weights are calculated by an equation similar  to Eq. 24.6 applied to the radar echoes received by a coherent pulse train transmitted by the radar . ch24.indd   34 12/19/07   6:00:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 8. J. Ruze, “The effect of aperture errors on the antenna radiation pattern,” Nuovo Cimento, Suppl .,  vol. 
 Moser, G.; Serpico, S.B. Generalized Minimum-Error Thresholding for Unsupervised Change Detection from SAR Amplitude Imagery. IEEE T rans. 
 In the second look, the transmitter  frequency is varied linearly at a ratefin one direction (i.e., increasing or decreasing  in frequency). During the roundtrip time to the target, the local oscillator has changed  frequency so the target return has a frequency shift, in addition to the doppler shift, that  is proportional to range. The difference in the frequency ∆f of the target return between  the two looks is found, and the target range calculated from  Rc f f=∆ 2 (4.11) The problem with only two FM segments during a dwell is that, with more than a  single target in the antenna beamwidth, range ghosts result. 
 3.1. Differential Interferogram Generation The image acquired on 17 September 2016 is selected as the super master image, and the remaining 19 images are slave images. The selection of interferograms is constrained by a maximum spatial baseline of 630 m (45% of the critical spatial baseline) and a maximum temporal baseline of 350 days. 
 As in the antenna of Fig. 7.13, the  parabolas consist of closely spaced parallel wires that reflect the polarization radiated by the  feed, but pass the ortliogonal polarization. The planar mirror rotates the plane of polarization  90" on reflection. 
 l 2  (n-1)10~ = N = 77:r + 3.73 x 10\, (12.9)  where p = barometric pressure, mbar (1 mm Hg 1.3332 mbar)  e = partial pressure of water vapor, mbar  T = absolute temperature, K ..  The parameter N = (n -1)106 is the "scaled-up" index of refraction and is called n:fi·actiPity.  It is often used in propagation work instead of n because it is a more convenient unit. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 23.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 For targets of more complex structure, the extent of the pseudo-monostatic region  is reduced. 
 Phased Array Antennas.  The phased array antenna has an aperture that is assem - bled from a great many similar radiating elements, such as slots, dipoles, or patches,  each element being individually controlled in phase and amplitude. Accurately pre - dictable radiation patterns and beam-pointing directions can be achieved. 
 Interferometric phase image of near-ﬁeld InISAR 3-D imaging. ( a) Traditional imaging approach, ( b) Global sparsity mixed sum norm processing; ( c) Global sparsity mixed Euclidean norm processing ( d) Global sparsity mixed inﬁnite norm processing. 4.1.3. 
 M., and D. L. Moffatt: Transient and Impulse Response Approximations, Proc. 
 WIDTH  INCREASING THE NUMBER OF LOOKS REDUCES SPECKLE  BUT AT THE COST OF COMPROMISING RESOLUTION -ORE ON THIS TRADE 
 III and VI (adapted from [ 9]).Airborne Maritime Surveillance Radar, Volume 1 3-14. iii. Adjust the crystal current control to give a meter reading of 0.25 –0.3 mA and turn the tuning knob on the indicator unit until the signals are at maximum. 
 Inthk case the simultaneous but opposite switching ofthetwo tubes eliminates theplateau ifthetwo cir-. 510 THERECEIVING SYSTEhl—INDICA TORS [SEC. 1310 cuits areproperly matched, and thesignal grids can therefore beinfull operation atalltimes. 
 The matched filter specifies the frequency  response function of the IF part of the radar receiver. Obviously, the receiver should be  designed to generate as little internal noise as possible, especially in the input stages where the  desired signals are weakest. Although special attention must be paid to minimize the noise of  the input stages, the lowest noise receivers are not always desired in many radar applications ir  other important receiver properties must be sacrificed. 
 1.Asignal ofafew volts from the detector must beamplified and transmitted totheindicator, thesignal level attheindicator being usually about 20volts, although some types ofindicator require a much higher voltage. 2.The amplifier must have good transient response, asdefined by thefollowing: itmust pass long pulses with little “droop” onthe top ofthe pulse; this requires good low-frequency response. The risetimel must bedefinitely shorter than thepulse length, and the overshoot onapulse should beheld to10per cent orless; these factors are determined by the high-frequency response. 
 This is due to the phase  quantization that results from digital phase shifters.Is4 For most applications, however, tllese  quantization lobes do not limit the system performance significantly.  Limited-scan arrays. The scan angle of a conventional array antenna might typically rangc  from k45" to perhaps &60° in both angle coordinates. 
 Next, consider a sinc:-wave  signal of amplitude A to be present along with noise at the input to the IF filter. The frequency . 26 INTRODUCTION TO RADAR SYSTEMS  1 year  ·· 6 months  1,000  30 days  _,:;;. 
 WATER CONTENT  IN PRACTICE THE VISIBILITY IS AN APPROXIMATION OF THE LIQUID 
 Ê, 
 By referring to Fig. 16.13, one ob- serves that the mechanization for scan compensation is fundamentally similar to the DPCA mechanization except that the difference signal is applied in phase with the sum signal and amplified by an amount determined by the antenna rota- tion per interpulse period. The signals required, if the transmis- sion signal 2(6) that appears in each channel is neglected, are S(G) ± erpA(e), where [ is the ratio of the am- plification in the two channels chosen to maximize the clutter rejection. 
 J.W.:Marconi S600SeriesofRadars.Imaado. vol.23.pp.73-75.January. 1961<. 
 BEAM BEAMWIDTHS OF A FEW DEGREES  AFFORDING HIGH DATA RATES AND SIGNIFICANT RESISTANCE TO JAMMING AND INTERCEPT 4RANSMIT DATA RATES OF OVER  -BPS  AND RECEIVE DATA RATES OF UP TO  'BPS HAVE BEEN DEMONSTRATED USING A PRODUCTION !%3! AND A MODIFIED #OMMON $ATA ,INK #$,  WAVEFORM  -ODELING USING REPRESENTATIVE  -&!2 PARAMETERS INDICATES THAT PERFORMANCE BOUNDS ARE AT SEVERAL 'BPS THROUGHPUT OVER DISTANCES IN EXCESS OF  NAUTICAL MILES  SUBJECT TO -&!2 PERFORMANCE  PLATFORM ALTITUDE  TROPOSPHERIC CONDITIONS  AND FORWARD SCATTERING EFFECTS  )MPLEMENTATION REQUIRES ACCURATE ANTENNA POINTING  SINCE THERE IS RELATIVE MOTION  WITH RESPECT TO THE OTHER END OF THE LINK /NE TECHNIQUE INVOLVES THE USE OF AN OUT 
 A. Ratcliffe, of Cambridge, and Dr L. Huxley, of  Nottingham, who together built up Britain’s first ‘radar  university,’ wherein other scientists and workers could  learn how to work and develop radar. 
 Conv. Rec., part. 1 , March 1961, pp. 
 #ONFIGURATION  4HE RADAR  FRONT END CONSISTS OF A LOW 
 A. Torres, R. M. 
 Ó{°£{  2!$!2 (!.$"//+  THE RISK OF SUCCESSFULLY EMULATING A USEFUL TARGET BECAUSE A REPEATER HAS TO APPEAR IN  THE SAME TARGET RANGE CELL AND HAS TO EMULATE THE SAME TARGET DOPPLER 3IDELOBE #ANCELER 3,#  3YSTEM  4HE OBJECTIVE OF THE 3,# IS TO SUPPRESS  HIGH DUTY CYCLE OR EVEN CONTINUOUS NOISE 
 The clutter error signal is obtained by measuring the pulse-to-pulse phase  shift wdTp of the clutter return. This provides a very sensitive error signal. The aver - aged error signal controls a voltage-controlled coherent master oscillator (COMO),  which determines the transmitted frequency of the radar. 
  OR OFF 
 For this reason, height finders which use electronic scan usually radiate r,encil  beams rather than broad fan beams.  V-beam radar. This radar generates two fan beams: one vertical and the other slanted at some  angle to the vertical (perhaps at 30 to 45°). 
 King, R. J.:" Microwave Homodyne Systems," Peter Peregrinus Ltd., Stevenage, Herts. England, 1978  (an Inst. 
 J. G. Wieler and W. 
 At a scan angle q0, the beam steers with  frequency through an angle dq so that  δδq q≈f ftan (0 rad)  For wider bandwidths, time-delay networks have to be introduced to supplement  the phase shifters. Conformal Arrays.17,18 Phased arrays may conform to curved surfaces as  required, for example, for flush-mounting on aircraft or missiles. If the surface has a  large radius of curvature so that all the radiating elements point in substantially the  same direction, then the characteristics are similar to those of a planar array even  though the exact 3D position of the element has to be taken into account to calculate  the required phase. 
 , 
 3.10~ for triangular modulation. The beat note is of constant frequency except at  the turn-around region. If the frequency is modulated at a rate fm over a range AL the beat  frequency is  Thus the measurement of the beat frequency determines the range R. 
 Lucas, “Estimating the performance of  telecommunication systems using the ionospheric transmission channel—ionospheric commu - nications analysis and prediction program users manual,” Nat. Telecom. Inf. 
 MENTS FOR ,& TO %(& COMMUNICATIONS GROUND AND SKY WAVE   STRIKE AND ELECTRONIC COUNTERMEASURES  %LECTRONIC 3UPPORT -EASURES %3-  VULNERABILIT IES  AND MANY OTHER  APPLICATIONS !2%03 AND !0- ARE PRODUCTS OF THE ATMOSPHERIC PROPAGATION BRANCH OF THE 3PACE AND .AVAL 7ARFARE 3YSTEMS #ENTER 30!7!2393#%.   3AN $IEGO !2%03 WILL EXECUTE ON A PERSONAL COMPUTER DESKTOP OR LAPTOP  USING A -ICROSOFT 7INDOWS OPERATING SYSTEM SUCH AS .4    80  OR 6ISTA AND REQUIRES NO ADDITIONAL SPECIAL HARDWARE !2%03 MAY BE FREELY OBTAINED AT THE 52, LISTED IN THE FIRST REFERENCE "EFORE CONTINUING WITH THE DISCUSSION OF ELECTROMAGNETIC %-  PROPAGATION MOD 
 1970, fig. 30.  83. 
 Further increase of height decreased the attenuation until a secondary minimum was  obtained at 20 m height, after which the attenuation again increased (at least to a height of  30 m). On a ship it might not he practical to site a radar antenna 2 mover the sea. Instead it  might he sited at 20 m height. 
 The long pulse, asshown in Sec. 2.9, gives greater range, particularly inmapping land-water bound- aries. Itmust belonger than the upper discrimination limit ofground beacons. 
 DPCA and doppler processing is often interleaved with traditional bright  (20 dB or greater above background) target detection. Lower PRFs are usually used,  which imply relatively high pulse compression ratios, as shown in Table 5.1. Scan  rates are often slow with one bar taking 10 seconds. 
 A.V.:SystemforSpace-Scanning withaRadiated BeamofWaveSignals,U.S.Patent No.2.409.944, issuedOct.22,1946. 69.Croney, 1..and1.R.Mark:DesignofaVolumetric Frequency Scanning Antenna, Proceedings European MicrowQl'e Conference, Sept.8-12,1969,IEEConference Publication No.58,pp.148-151. 70.Okubo. 
 BEAM CLUTTER TO FIT A FIXED !-4) FILTER )N ORDER TO IMPLEMENT 34!0 AND ELECTRONIC SCANNING IN THIS RADAR  ALL  ELEMENTS  OF THE PHASED ARRAY ANTENNA ARE PROCESSED ON TRANSMIT AND RECEIVE 4HE SOLID 
 Ill.Tatarski. V.I.:"WavePropagation inaTurbulent Medium." McGraw-Hili BookCo..NewYork, 1961. 112.Tatarski. 
 70. Gupta, P. D.: Exact Derivation of the Doppler Shift Formula for a Radar Echo Without Using  Transformation Equations, Am. 
 TERM RELIABIL 
 --" Ê-9-/ 
 6.10FIGURE 6.5  Phase noise componentsFrequencySingle Sideband Phase Noise (dBc/Hz) 100 Hz 1 kHz 10 kHz 100 kHz 1 MHzSTALO Common Phase Noise LC(f) STALO Uncommon Phase Noise LU(f)Phase Noise after Do wncon version L ’(f) −120 −130 −140 −150 −160 −170−110−100 ch06.indd   17 12/17/07   2:03:15 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 CAL RESOLUTION IS  M IN MATERIAL HAVING A PERMITTIVITY OF  4HE  
 Theusualdetection criteriaemploytheconceptofdirectprobabil­ ity,whichdescribes thechanceofaneventhappening onagivenhypothesis. Forexample, the probability thataparticular radarwilldetectacertaintargetunderspecified conditions isa directprobability. Ontheotherhand,ifaneventactually happens, theproblem offorming the bestestimate ofthecauseoftheeventisaproblem ininIJerseprobability. 
 M RESOLUTION ACROSS  
 "$& #!"  %"'  
 Left range, right azimuth. The three rows present extracted phase histories, the real parts of the reference functions and their spectra. Figure 6. 
 IN BY PORT AUTHORITIES 3UCH SYSTEMS CAN ALSO BE USED FOR ALERTING MARINERS OF THE POSITION OF RECENT WRECKS AND OTHER TEMPORARY AND PERHAPS VISUALLY UNMARKED NAVIGATION HAZARDS ÓÓ°nÊ , ,Ê 
 This isespecially true oftheevaporation duct. 4.Substandard aswell assuperstandard radar ranges can becaused by refractive anomalies, ifthetransmission path isnearly horizontal. 5.Propagation atangles steeper than afew degrees with respect tothehorizontal isnotaffected bytherefractive anomalies here discussed. 
 PORT AZIMUTH INTERFEROMETER GROUND MOVING TARGET INDICATION '-4)  TARGET DETECTION AND TRACKING MODE 5SE OF THE THREE 
 BEAM  KLYSTRONS AND 474S v .AVAL 2ESEARCH ,ABORATORY  7ASHINGTON  $#  -2 
 METER DUAL REFLECTOR AND DUAL 
 TIME ON TIME SIDELOBE LEVELS ! PHASE PREDISTORTION TECHNIQUE IS DESCRIBED BY #OOK AND 0AOLILLO   WHICH REDUCES THE &RESNEL AMPLITUDE RIPPLE TO  ALLOW LOW TIME SIDELOBES TO BE ACHIEVED FOR ,&- WAVEFORMS WITH RELATIVELY SMALL TIME 
 Input: Subaperture echo data ri(i=1:I)and measurement matrix Φi, iterative parameter μ, maxmum iterative step Tmax. 1:Implement BP on the whole aperture data, estimate Tfrom the BP image. si=0(i=1:I),t=0. 
 The guns are positioned automatically bymeans ofservo- mechanisms, and afuze-setting mechanism isautomatically adjusted to cutfuzes tothetime-setting indicated bythe computer. zThe duties of the gun crew arethe purely mechanical ones ofsupplying ammunition and loading. The Army system ofantiaircraft fire control just sketched was out- standingly successful inthe past war. 
 LYZED THIS SITUATION FOR  .         AND  PULSES AND CALCULATED THE DETECTION THRESH 
 TAINTY TO LESS THAN  D" 3INCE 3EASAT WAS NOT YAW 
 On  this graticule will be drawn, in black line, an outline  map of the whole area, to north, south, east, and west  of our station, and we must imagine that our radar trans-  mitting and receiving aerials (if, indeed, a common-TR  array is not used) are about to be swung, say, in clock-  wise fashion, looking out along a narrow beam, and with  this beam being swung round in a full circle of 360  degrees.  On our CRT the trace is arranged to run from the  centre of the tube to the outer edge, and, of course, this  trace represents the maximum range of the equipment,  just as in Type A. The tube is intensity-modulated, so  that if an echo is received back along this particular line  of shoot it will appear on the tube as a bright spot. 
 and a decrease in moisture content. Thus this warmer. drier air lies above the  cooler. 
 Aconstant phaseshiftcanbeinsertedinthepath toeachelement, withavaluethatdiffersfromelement toelement byamounts thatare unrelated tothebitsize.Thisaddedphaseshiftisthensubtracted inthecommand senttothe phaseshifter.Withanoptical-fed array,suchasthereflectarray orthelensarray,decorrda­ tionofthephasequantization isinherent inthearrayconstruction. Inthiscase,thereduction inpeakquantization lobesissaidtobeequivalent toaddingonebittothephaseshiftersina loo-element array,2bitsinalOoo-element array,and3bitsina5000-element array. Themaximum pointing errorduetoquantization, is115 n:I 1:100/08="42-8 where 0Bisthebeamwidth. 
 85 Inthe case ofbeacons interrogated and received bya radar set, ~,is nearly equal toX,;(Gd ~..usually equals (GE,) ~..since thesame antenna islikely tobeinvolved; and (GR,)~~. usually equals (G~,)~,. since beacon antennas forreceiving and transmitting need tohave thesame radiation pattern and aretherefore alike. 
 16.7, where the first four traces represent successive sweeps on the A-scope ofFig. 165. The‘“:’;~ “’‘~ “‘~ Cancelled signals 2minus1 A 33s2 w 4“ ‘~ FIG.16.7.—Pulse-to-pulse cancellation. 
 Interconnection diagram for ASV Mk. III [ 5]. Table 3.1. 
 J. Bahl: "Millimeter Wave Engineering and Applications," John Wiley & Sons, New York, 1984, pp. 75-152. 
 Secondly, the gain of our receiver must be enough to  cause the beam of the CRT to be deflected. Physicists  can prove that all signals are received on all aerials; the  simple crystal set, if tuned to about two metres, might  be able to receive radar signals; but there would be no  point in that sort of reception, as the amplification would  be nil, and we should see or hear nothing.  Reverting to ‘grass’ for a moment, we are faced with  the fact that receiver noise is of multiple origin, but quite  a lot of high-frequency noise is picked up in the aerial and  the transmission system linking aerial and receiver; the  rest, such as valve noise (or electrode noise, as it is  sometimes called), crops up in the initial stages of the  receiver. 
 Skolnik, Radar Handbook , 2nd Ed., New York:  McGraw-Hill, 1990; 1st Ed., New York: McGraw-Hill, 1970.  3. W. 
 The circuits ofdiagrams(b) and (c)ofFig. 13.27 require the least power input. The 6AS6, which has asharp suppressor cutoff, is the most satisfactory tube unless considerable load current isneeded. 
 AD 65881, Mar. 1, 1954. (Reprinted in Ref. 
 BAND AND  +A 
 Chaff may be distinguished from moving  aircraft targets on the basis of its slower velocity. Discrimination is performed either by thc  radar operator or automatically with MTI.  Chaff dropped from an aircraft can also be used to" break lock" on tracking radars; that  is, if a tracking radar is" locked on" and fol.lowing a particular target, the dropping of chaff  might cause the tracker to follow the chaff and not the target. 
   -4) 2!$!2  Ó°Î THE PHASE OF A REFERENCE OSCILLATOR IN THE RADAR )F THE TARGET MOVES BETWEEN PULSES  THE  PHASE OF THE RECEIVED PULSE CHANGES &IGURE  SHOWS A SIMPLIFIED BLOCK DIAGRAM OF A COHERENT -4) SYSTEM 4HE 2&  OSCILLATOR FEEDS THE PULSED AMPLIFIER  WHICH TRANSMITS THE PULSES 4HE 2& OSCILLATOR &)'52%  A  .ORMAL VIDEO AND  B  -4) VIDEO 4HESE 00) PHOTOGRAPHS SHOW HOW EFFECTIVE AN -4)  SYSTEM CAN BE !IRCRAFT APPEAR AS THREE CONSECUTIVE BLIPS IN THE RIGHT 
 BASED UNDERLAY  AND RADARS INTEGRATED  WITH !)3 2ADARS DESIGNED FOR SMALLER VESSELS TEND TO HAVE A COMPLETELY WATERPROOFED USER INTERFACE AS THEY ARE OFTEN USED IN MORE EXPOSED AREAS AND BY OPERATORS WITH WET  SALTY HANDS )N GENERAL  TRACKER BALLS  ALTHOUGH THEY GIVE MORE PRECISE CONTROL AND ARE COMMON ON SHIPBORNE RADARS  HAVE BEEN FOUND TO BE UNSATISFACTORY IN THE ENVIRONMEN 
 Jezek, “Coherent radar ice thickness measurements over Greenland  ice sheet,” Journal of Geophysical Research , vol. 106, pp. 33761–33772, 2001. 
 CW AND FREQUENCY-MODULATED RADAR 91  harmonic as compared with a practical CW radar because ·the transmitter leakage noise is  suppressed by the 11th-order Bessel function. The loss in signal energy when operating with the  J-' Bessel component is reported9·3u4 to be from 4 to 12 dB. Although two separate transmit­ ting and receiving antennas may he used, it is not necessary in many applications. 
 .., which defines a filter  centered at dc, the prf, and its harmonics. This filter passes the clutter component at dc, hence  it has no clutter rejection capability. (Its output is useful, however, in some MTI radars for  providing a map of the clutter.) The first null of the filter response occurs when the numerator  is zero, or when!= 1/NT, The bandwidth between the first nulls is 2/NT and the half-power  bandwidth is approximately 0.9/NT (Fig. 
 Global Assimilation of Ionospheric Measurements, Park City, Utah, 2001, http://gaim.cass.usu   .edu/GAIM/htdocs/present.htm . 44. Global Assimilative Ionospheric Model, JPL, http://iono.jpl.nasa.gov/gaim/index.html . 
 4.Slrallon, J.A.:"Electromagnetic Theory," McGraw-Hill BookCompany, NewYork,1941. 5.Sherman. J.W.:Aperture-antenna Analysis, chap.9of"RadarHandbook," M.1.Skolnik (cd.). 
 Rogers, N.C.; Quegan, S.; Kim, J.S.; Papathanassiou, K.P . Impacts of ionospheric scintillation on the BIOMASS P-band satellite SAR. IEEE T rans. 
 There  are two methods for interleaving high and low priorities. The first is preemption of control by a  Iiigiier-priority task as soon as it arises. The interrupted task is put aside in such a way that it  can be resutiied when time permits. 
 The spatially-variant phase errors caused by the spatially-variant Doppler parameters. ( a) The phase error caused by the Doppler rate; ( b) the phase error caused by the derivative of the Doppler rate. The data at the range time domain and the azimuth frequency domain in the step of the azimuth compression for the high-squint airborne SAR imaging algorithm is as follows. 
 The separation of  transmitting and receiving antenna (a bistatic construction) yields to an insufficient uncoupling (e.g. 80 dB).  3 procedures have been developed, through which CW Radar can become opera- tional:   - Measurement of the frequency modulation due to the Doppler Shift. 
 Laing: Point-Scatterer Formulation of Terrain Clutter Statistics, Nara/  Resmrcl, Lahoratory Report 7459. Sept. 27, 1972, Washington. 
 LAUNCH    PERFORMANCE ASSESSMENT REVIEW v !CTA !STRONAUTICA  VOL   PP n    3 2 #LOUDE  ' +RIEGER  AND + 0 0APATHANASSIOU  h! FRAM EWORK FOR INVESTIGATING SPACE 
 LOCK THE RADAR TO THE CLUTTER FILTER  ONE COULD CENTER THE CLUT 
 Digital processors are likely to employ more complex filtering schemes, but the  simple canceler is shown here for convenience. Almost any type of digital storage device can be  used. A shift register is the direct digital analogy of a delay line, but other digital computer  memories can also be used effectively. 
 Barton, D. K.: "Radar Systems Analysis," Prentice-Hall, Englewood Cliffs, NJ., 1964, p. 206. 
 AES-Il, July 1975. Reprinted in Barton, D. K.: "CW and Doppler Radars," vol. 
 LATE A COMMON CARRIER FREQUENCY THAT DOES NOT APPEAR EXPLICITLY 4HE JAMMING SIGNALS IN THE CHANNELS MAY BE REGARDED AS SAMPLES OF A STOCHASTIC PROCESS HAVING ZERO MEAN VALUE AND A CERTAIN TIME AUTOCORRELATION FUNCTION &OR LINEAR PREDICTION PROBLEMS  THE SET OF SAMPLES  6 IS COMPLETELY DESCRIBED BY ITS  . 
 D. Schleher, “Low probability of intercept radar” in IEEE International Radar Conference ,  1985, p. 346. 
 9 (degrees) FIG. 16.18 DPCA clutter residue versus angle for normalized displacement Vn = 0.04 and normalized scanning motion Wn = 0.04. 20 wavelengths long. 
 The potential benefits of full polarization control on transmit have been  assessed and a number of experimental studies carried out, but no operational system  has gone down this path. The antennas and power amplifiers used in HF broadcast stations have much in  common with HF radar, that is, to maintain a specified level of illumination over a  designated area. To achieve this goal, many multiband and steerable broadcast anten - nas66–68 employ large vertical apertures. 
 Such an echo would appear to be at a  much shorter range than the actual and could be misleading if it were not known to be a  second-time-around echo. The range beyond which targets appear as second-time-around  echoes is called the rna.uintttrn trr~arnhigtrous rattge and is  where./, = pulse repetition frequency, in Hz. A plot of the maximum unambiguous range as a  function of pulse repetition frequency is shown in Fig. 
 Thecohoisastableoscillator whosefrequency isthesameastheintermediate frequency usedinthereceiver. Inaddition to providing therefcrence signal.theoutputoCthecoho.fcisalsomixedwiththelocal-oscillator fre4ucIlcy I,.Thclocaloscillator Illustalsobeastableoscillator andiscalleds(a!o,fors(c/bk localoscillalor. TheRFechosignalisheterodyned withthestalosignaltoproduce lheIF si~naJ,illslasintheconventional slIperhetcrodyne receiver. 
 Small beacons have been used formarking life rafts and small target rafts. Airborne Radar. 1.Fixed ground beacons. 
 Dai, K.; Liu, G.; Li, Z.; Ma, D.; Wang, X.; Zhang, B.; Tang, J.; Li, G. Monitoring highway stability in permafrost regions with x-band temporary scatterers stacking InSAR. Sensors 2018 ,18, 1871. 
                                            
 Therefore the theoretical conversion loss can never be less than 3 dB with this  configuration. (The image frequency is defined as that frequency which is displaced from the  local oscillator frequency fLO by the IF frequency, and which appears on the opposite side of  the local oscilfator frequency as the signal frequencyh,. It is equal to 2f~0 - JRF .)  Short-circuiting or open-circuiting the image-frequency termination results in a" narrow-  hand " mixer. 
 Ó{°În  2!$!2 (!.$"//+  $ETECTION IN A CLEAR ENVIRONMENT IS A FEATURE OF EARLY 
 METRICAL MODES SUCH AS THE 4% MODE FOR  ( 
 102. Riley. J. 
 RATIO FOR EACH DOUBLING OF THE SAMPLE RATE 4HUS  FOR HIGH DYNAMIC 
 In summer, s 0 for MY ice  decreases to about the same level as that of FY ice. Figure 16.42153 shows this and typi - cal angular responses. These curves are for 13.3 GHz, but the results would be similar  at any frequency down to S band. 
 8.16 can be used to scan a pencil beam in  elevation, with mechanical rotation providing the azimuth scan. The AN/SPS-48, Fig. 8.17, is  such an example. 
 BORESIGHT RADIAL VELOCITY AT THE SAME RANGE BY  666 66 6ER" GG G 
 Figure 13. SPARX SNR estimated map superimposed on the acquisition scenario top view. 6. 
 The center antenna is the high-gain radar  antenna to detect targets notwithstanding impulsive and noise-like interferences. The  right-hand side antenna is a low-gain auxiliary that is used for SLB processing in  the main channel. The adaptive cancellation of NLI received by the main antenna is  achieved by the linear combination of the SLC and MAIN  signals with the adaptive  weights W1 and 1, respectively; the resulting adapted signal MAIN ' doesn’t contain the  NLI. 
 NENTS v )%%% 4RANS  VOL !0 
 Duncan, “Sea clutter measurements on four  frequencies,” Naval Res. Lab. Rept. 
 92. J. Frank, C. 
 The MTI improvement  factor limitation due to the STALO may be expressed as the ratio of the STALO power  to the total integrated power of the return modulation spectrum it creates at the output  of the MTI filters. Figure 6.6 illustrates the effect of the overall filtering, consisting of  MTI filtering and receiver filtering on the residue power spectrum. The integrated residue power due to the STAMO phase noise is given by  P H f L f dfresidue= ′ −∞∞∫| ( ) | ( )2  (6.11) where  H(f) =  combined response of receiver and doppler filters, normalized to 0 dB  noise gain  L' (f) = phase noise after downconversion as defined in Eq. 
 LENGES IN THE DESIGN OF A UNIVERSAL SIMULATOR  AS THE SYSTEM DESCRIBED IS BASED ON TESTING NONCOHERENT PULSED RADARS 3YSTEMS BASED ON DIGITAL 2& MEMORY MAY HAVE TO BE DEVISED  STORING WAVEFORMS THAT CAN BE SUBSEQUENTLY PROCESSED 4ARGET AND CLUTTER  MODELS WOULD OBVIOUSLY NEED TO APPROPRIATELY TAKE INTO ACCOUNT  DOPPLER EFFECTS INTRO 
 Thus, the ratio of main-beam clutter to system noise measured at the re- ceiver output (CIN)9 including the fluctuation margin as discussed above, is the predominant parameter that determines stability requirements. However, at low spurious modulation frequencies, other constraints may become limiting. Types of Spurious Modulation. 
 pp.  X06 8 14. Novcmhcr. 
 but it is always less than this with a single antenna because of practical  difficulties. Tlie cosecant-squared antenna may be generated by a distorted section of a parab-  ola or by a true parabola with a properly designed set of multiple feed horns. The cosecant-  squared pattern may also be generated with an array-type antenna. 
 02& 2ANGING  2ANGE 
  +1 
 FORCE TECHNIQUE USED TO ELIMINATE TARGETS WITH RADIAL  VELOCITIES OF LESS THAN APPROXIMATELY  o KNOTS RESULTING IN A TOTAL REJECTION INTERVAL  OF  KNOTS 4O KEEP THIS REJECTION OF VELOCITIES TO NO MORE THAN  OF THE DOPPLER SPACE AVAILABLE  THE AMBIGUOUS VELOCITY MUST BE ABOUT  KNOTS 4HIS REQUIRES 02&S OF   (Z AT , BAND    (Z AT 3 BAND  AND   AT 8 BAND UNAMBIGUOUS    RANGES  RESPECTIVELY   NMI   NMI  AND  NMI  4HE MAIN CHALLENGE WITH THIS TECH 
 At low altitude, variations in the water-vapor pressure (humidity) are probably the dominant  effect. At high altitude, there is little water vapor, and changes in temperature have the mosl  effect on the refractive index.  Reflections from clear-air turbulence are thus a potential source of radar angel echoes. 
 F.: The Applicability of Bistatic Radar to Short Range Surveillance, IEE Conf. Radar 77, Publ. 155, pp. 
 PLY RIPPLE  THE RELATIVE EFFECT OF THE INSTABILITY CAN BE DETERMINED BY LOCATING THE RESPONSE ON THE VELOCITY RESPONSE CURVE FOR THE -4) SYSTEM FOR A TARGET AT AN EQUIVA 
 Rrown. R. M., Jr., and R. 
 More frequently, however, 2D plots are sufficient and more convenient to measure and plot. For example, if the intersection of the 3D pattern of Fig. 6.1a with a vertical plane through the peak of the beam and the zero azimuth angle is taken, a 2D slice or "cut" of the pattern results, as shown in Fig. 
 HORIZON RADAR v IN  'OODMAN  * - ED    0ROC %FFECT )ONOSPHERE ON 2ADIOWAVE 3YSTEMS   /.2!&', 
 This small pulser nearly always requires auxiliary voltage sup- plies and, inaddition, the switch-tube control grid must bemaintained beyond cutoff during the interpulse interval. Inline-type pulsers, the ‘‘triggering” ofthe switch (orinitiation ofthe discharge) isusually accomplished with much less power than isnecessary todrive the grid ofthehard tube; inmost cases, thedriver power output isonly afew perI ISimple considerations show that, when chargi~g acondenser from zero tothe power supply voltage through aresistance, asmuch energy isdissipated intheresist- ance asisstored inthecondenser.. SEC. 
 13.Trunk,G.V.:RadarProperties ofNon-Rayleigh SeaClutier,IEEl.:;'!'rtllIS.,vul.AI:S-K,pp.1%204, March,1972. 14.Schleher, D.c.:RadarDetection inWeibullClutter,IEEETrans.,vol.AES-12, pp.736-743,Novem­ ber,1976. 15.Fay,F.A.,J.Clarke,andR.S.Peters:Weibull Distribution AppliestoSeaClutter,Intt'rnatiollal COt!{erence RADAR-??, pp.101-104, lEEConference Publication no.155. 
 TO 
 FIELD FEATURES THAT CANNOT BE OBTAINED FROM THE GLOBAL  
 #ODED 7AVEFORMS  )N PHASE 
 Metal members  are not only superior in electrical performance to the equivalent dielectric members but metal  space-frame radomes are generally cheaper and easier to fabricate, transport, and assemble,  and can be used for larger diameter configurations.  Aluminum structural members, which might be larger than steel of equivalent strength,  are of light weight, noncorrosive, and require no maintenance. The load-bearing framework is  covered with low-loss fiberglass-reinforced plastic panels. 
 FREE SPACE AS CAN BE TOLERATED )N PRACTICE  THE ANTENNA AREA USUALLY IS CHOSEN TO BE AT LEAST A FACTOR OF TWO LARGER THAN THIS MINIMUM WOULD SUG 
 It illuminates tlie low angles. No monopulse angle measurement would  be attempted wit11 this beam. Tile otller two beams cover tlie liigller angles with monopulse  processing. 
 Small craft and buoys become invisible on the  display, creating danger to life. IMO recognized this problem and, in order not to con - strain opportunities for innovative radar design, removed the requirement that 3 GHz  radars be compatible with existing racons. Gallium Nitride and other microwave power semiconductors,19 developed primar - ily for broadband communications links, have enabled CMR manufacturers to use  these in the radar transmitter to replace magnetron-based designs. 
 Gangeskar, “Automatic oil-spill detection by marine X-band radars,” Sea Technology ,  August 2004. 18. T. 
 PLIES THE QUADRATIC TERM IN THE ARGUMENT OF THE COSINE  AND A FREQUENCY OFFSET RELATIVE  TO THE )& CARRIER FREQUENCY F)& GIVEN BY    DA T TFFD2 2 
 Obviously, in the near sidelobes or main beam, the range  for a 60 dB pulse will be much greater.84 5.4 A-S MODE DESCRIPTIONS & WAVEFORMS Terrain Following, Terrain Avoidance.  The next example is terrain following,  terrain avoidance (TF/TA) shown in Figure 5.25. In terrain following (TF), the antenna  scans several vertical bars oriented along the aircraft velocity vector and generates an  altitude-range profile that is sometimes displayed to the pilot on an E-scan display. 
 With Five Plates in Half-tone and Line  Drawings and Diagrams in the Text  GEORGE G. HARRAP & CO. LTD  LONDON SYDNEY TORONTO BOMBAY  . 
 There is another important difference between physical linear arrays and syn- thetic linear arrays. This difference results in the synthetic aperture having a res- olution finer by a factor of 2 than that corresponding to a real linear array of the same length. Qualitatively, the following discussion indicates the physics result- ing in this factor of 2. 
 The  mechanism of diffraction is especially importan~ at very low frequencies (VLF) where it  provides world-wide communications. However, at radar frequencies the wavelength is small . PROPAGATION OF RADAR WAVES 457  compared with the earth's di1ncnsions and little energy is diffracted. 
  A )N TERMS OF THE BISTATIC  TRIANGLE  THE REQUIRED RECEIVE BEAM 
 928-938, 1946.  3. Wathen, R. 
 The dynamic range of the digitized (false-color) PPI was 30 dB, and some of the clutter contrasts, across what are obviously extremely sharp boundaries, were almost this great. 13.4 THEORIESOFSEACLUTTER The sea surface is so rich in potential scattering structures that in seeking to un- derstand the phenomenology experimenters and theorists alike have proposed and have found support for almost any imaginable model. However, aside from providing an intellectual basis for "understanding" sea clutter phenomena, a the- ory of sea clutter should serve the practical purpose of providing accurate a priori predictions of all aspects of clutter behavior under all possible environmental conditions. 
 BEHAVED AND OBSERVED POSITION ERRORS WOULD BE DUE TO IONOSPHERIC FLUCTUATIONS /NLY THE SINGLE $)2 CONTAINING THE AIRCRAFT NEED BE INTERROGATED 4ASK   BARRIER SUR 
 Unlike an airborne platform that can go anywhere  at any time (subject to fuel and air-space limitations), a satellite’s position and veloc - ity when in orbit about a planetary body are rigidly governed by orbital dynamics,  summarized compactly by Kepler’s laws. Further, access by an SBR to a given area  of interest depends on the rotation rate of the planet, as well as the satellite’s position  along its orbit and the radar’s viewing geometry. Thus, the primary parameters to be  included in SBR mission design include orbital altitude, spacecraft on-orbit velocity  (and hence period), orbit inclination, and the rotation rate of the planet. 
 R. Hynes and R. E. 
 FIERS ! KEY ATTRIBUTE THAT MAKES 'A!S AN ATTRACTIVE TECHNOLOGY IS THAT THE 'A!S &%4 CAN BE FULLY INTEGRATED WITH THE PASSIVE CIRCUITRY THAT IS NECESSARY TO PROVIDE THE BIAS 
 ISAR imaging reconstruction technique with stepped frequency modulation and multiple receivers. In Proceedings of the 24th Digital Avionics Systems Conference (DASC’05), Washington, DC, USA, 30 October–3 November 2005. 14E2-11. 
 RADAR COMMITTEE 2 OCTOBER 1942 [ 1] The Aim of ASV The primary function of ASV is to provide a means for aircraft to locate, and home on to, enemy shipping beyond visual range, thereby increasing the search area ofindividual aircraft. It should further provide information to assist in the location ofenemy aircraft when early warning information is available. Secondly, ASV is required to enable aircraft to locate and home on to friendly shipping convoys, to whom they are providing escort protection. 
 113. J. C. 
 13. Cantafio, L. J.: Space Based Radar Concept for the Proposed United Nations Interna- tional Satellite Monitoring Agency, MiL Microwaves Conf., London, Oct. 
 The known Uarker codes are shown in Table 11.2. The longest is of length 13. This is a  relatively low value for a practical pulse-compression waveform. 
 Fehlner6 recomputed Marcum's and Swerling's results and presented them in the more useful form of . curves with the signal-to-noise power ratio as the abscissa. The fluctuating-signal problem has subsequently been further treated by Kaplan,7 Schwartz,8 Heidbreder and Mitchell,9 Bates,10 and others. 
 A longer time allowed for track formation (higher  M/N) allows the radar detection process to use lower detection thresholds, result - ing in better radar sensitivity. For any given set of radar parameters, M/N track  formation criterion, and probability distribution of clutter amplitudes, there exists  an optimum false-alarm rate that minimizes the signal-to-noise ratio required to  detect targets. Figure 7.38 illustrates this optimization for an eight-scan track for - mation process. 
 These errors, which resulted from. 540 THERECEIVING SYSTEM—INDICATORS [SEC. 13.17 Automutic Triggering oftheTransmitter. 
 Thus, the CEA probably should be a candidate  when considering any new UHF radar system, as well as radars at lower frequencies,  especially if mutual interference is a potential problem. Magnetron . It was mentioned that the magnetron was what made microwave  radar possible in the 1940s. 
 The simulation results demonstrate that the proposed KA-DBS imaging algorithm outperforms the other algorithms. 4.2. Real Data We study the performance of the newly proposed KA-DBS algorithm by resorting to real data set in this section. 
 After the usual trigonometric manipulation, the difference jut/ takes the form li, = U1 cos [(I0(Vo + ^) - 4> + D cos o>m (/ - I)] _ 2Aft . <»mTD = sin ——<ow 2 The reflection phase 4> may generally be disregarded and JJL, expanded in a Fourier series.6 ^ = UAMD) cos O0 ( T0 + — J + 2 (- \)^w Jn(D) \ sin L>m (r - J) \ V c / /i odd L L \ z/ + «o(r0 + ^)] - sin [n.m (, - I) - n0(r0 + ^)]} + 2 ( - If'''Jn(D) (cos Lm (/ - f) + "o (TO + ^')1 n even LL \z/ \ C/J )-M-i)-4.+T)]}) . CHAPTER 15 MTI RADAR William W. 
 Equallengthsoflinetransmit theenergyto eachelementsothatnounwanted phasedifferences areintroduced bythelinesthemselves. (If thelinesarenotofequallength.acompensation inthephaseshiftmustbemade.)Theproper phasechangeforbeamsteering isintroduced bythephaseshiftersineachofthelinesfeeding theelements. Whenthephaseofthefirstelement istakenasthereference, thephaseshifts required inthesucceeding elements are1>,21>,31>,...,(N~I)¢. 
 C.: "Electromagnetic Waves and Radiating Systems," sec. 12.17. Prentice-Hall. 
 Frequency multipliers multiply the phase distortion  of the input signal and often have significant phase distortion themselves. Distortion of  the LO chirp signal phase can have a significant effect on the compressed pulse perfor - mance, either distorting the compressed pulse shape or degrading sidelobe performance  (Section 6.13). Phase errors can be measured using a test target injected into the receiver  and measuring the phase ripple at the receiver output. 
 The last integral is the energy E  contained within the signal si(t) and also is a constant. The second integral is not a constant.  The a posteriori probability can be written  378INTRODUCTION TORADAR SYSTEMS Lettheeventx=SNrepresent signal-plus-noise, andlettheeventybethereceiver input, whichmayconsistofeithersignalo;pius-noise ornoisealone.Equation (10.22)maybe. 
 Brookner (ed.), Norwood, MA: Artech House, 1977. 38. J. 
 FIG. 5.5 Cross section of a GaAs power MESFET chip. majority carrier devices and exhibit inherent thermal stability. 
 120. pp. 1229 1232. 
 F. Coffey: Space-Based Bistatic Radar: Opportunity for Future Tac- tical Air Surveillance, IEEE Int. Radar Conf., pp. 
 From data ob- tained in signal detection experiments during World War II at the Naval Research Laboratory, Haeff21 devised the following empirical expression: c"£['*£r where Bn is the noise bandwidth, T is the pulse length, and a is the product of T and Bn>opl (optimum bandwidth). Figure 2.1 is a plot of Haeff s equation. Actually, Haeff deduced from his experiments, as did North from theoretical analysis, that Bnj0pl = I/T; that is, a = 1, for rectangular-shaped pulses. 
 [ CrossRef ] 9. Liu, C.; Vachon, P .W.; Geling, G.W. Improved ship detection with airborne polarimetric SAR data. 
 16.13. Since the transmitted pattern 2(6) appears in both channels, it is not shown. A single-delay system would not have the second delay line and subtracter. 
 This led tothe effort that the British put into developing agenerator ofmicrowaves which could give pulse power adequate forradar use. Byearly 1940, aBritish version ofthe multicavity magnetron had been developed tothe point where itwas anentirely practicable source ofpulsed microwave energy, and thehistory ofmodern radar had begun. 1.7. 
 Generally, the fault lies not with the theory, but in the fact that it is'not possible to  reproduce precisely in practice the necessary aperture illumination specified by synthesis  theory. Small, but ever-present, errors occur in the fabrication of an antenna. These contribute  unavoidable perturbations to the aperture illumination and result in a pattern different in  detail from the one anticipated. 
 BASED 3!2 DESIGN    ARE MORE LIMITED THAN FOR AIRBORNE SYSTEMS  DUE PRIMARILY TO THE CONSTRAINTS IMPOSED BY VIABLE ORBITS  INCLUDING ESPECIALLY SENSOR VELOCITY  RADAR RANGE  2   AND SYSTEM COST  4HE FOLLOWING PARAGRAPHS REVIEW THE MAJOR THEMES 02& #ONSTRAINTS  4HE RULES THAT GOVERN THE PULSE REPETITION FREQUENCY 02&  OF  A SPACE 
 One of the most accurate methods for obtaining the atmospheric profile of  the index of refraction is with an airborne microwave refractometer.40·41 In one version,39 two  precision microwave transmission cavities are employed, one of which is open to collect a  sample of the atmosphere. The other is hermetically sealed and acts as a reference. The two  cavities arc fed hy the same microwave source which is swept in frequency. 
 MING OVER ALL AMBIGUITIES OF THAT RANGE GATE THAT ARE WITHIN THE MAIN BEAM  # .0C ,K 4"'' 2#S N42 AV AZLQ T PS A       C O S  £ £    4HE SUMMATION LIMITS ARE THE LOWER AND UPPER EDGES IN THE ELEVATION DIMENSION OF THE SMALLER OF THE TRANSMIT AND RECEIVE BEAMS WHERE  P AZ   AZIMUTH HALF 
 A disadvantage of this form of scan  converter is its low resolution.  A digital memory can be used as the storage device in a scan converter to overcome  the limitations of the analog storage tube.  Rear Port. 
 24-26, 1984. 14. "The Implication of Establishing an International Satellite Monitoring Agency," UN Publ. 
 Tlie rreqiicncy-response cliaracteristics of many practical radar receivers are such that  tlic 3-dl3 i~rici tlic tioisc I~nt~tlwidtlis tlo riot differ appreciably. Tlierefore tlie 3-dl3 I~itnciwidtli  rnay be used in niatiy cases as an approximation to the rioise bandwidth.'  The noise power in practical receivers is often greater than can be accounted for by  thertnal noise alone. The additional noise cotnpotlents are due to mechanisms other than the  tlierrnal agitation of tlie conduction electrons. 
 38The valueof0"0decreases withdecreasing grazingangleuntil,inthiscase,atabout3.50thevalueof 0"0actually increases asthegrazing angleislowered. Thisbehavior issaidtobeduetothe stronger backscatter fromvertically oriented structures (trees,buildings, crops)asthegrazing angleapproaches zero.Otherreported measurements atlowgrazinganglesofheavilywooded, rollinghillstypicalofNewEngland show 0"0attheseanglestobeunaffected bychanges in seasonorweather. 39 Therealsoexistsmuchexperimental dataofthe0"0ofcropssuchascorn,soybeans, milo, alfalfa,andsorghum.48-53Theradarbackscatter depends notonlyonthetypeofcrop,and frequency, butalsoonthestateofitsgrowth,themoisture contentofthesoil,andthetimeof day. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.50  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 This is a quite low RCS at HF, indicating that when conditions are favorable, very  small targets are potentially detectable. 
 SOLUTION METHODS ONE OF SEVERAL PRACTICAL IMPLEMENTATIONS IS DESCRIBED IN 'RIFFITHS  "Y VIRTUE OF THEIR SELF 
 8)were designed foruse with this equipment. The type Ldisplay isjust aswell suited tohoming ona beacon asitistohoming onaradar target, and the navigational aid provided bybeacons was very useful inbringing aircraft home after long seapatrols. Avery similar equipment operationally, but ofgreatly reduced total weight, has been widely used bythe IJ.S. 
 Element Factor and Gain of Planar Arrays.  The maximum gain of a uniformly  illuminated and lossless aperture of area A, with a broadside beam, is G Amax / . =42π λ    ch13.indd   13 12/17/07   2:39:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 where ss = rms angle error in same angular units as qB  A(fs) = rms-fractional-modulation noise density in vicinity of scan rate  ks = conical-scan error slope ( ks = 1.6 for system optimum22)  qB = one-way antenna beamwidth  b = servo bandwidth, Hz A sample calculation for an fs of 120 Hz, where A(fs) from measured data taken on a  large jet aircraft is approximately 0.018/ Hz, qB is 25 mils, and b is 2 Hz, gives a ss  of 0.42 mil rms. In the case of a periodic modulation, where a spectral line falls within the band   fs ± b, the rms noise is ss = 0.67qB A(fs), where A(fs) is the rms fractional modulation  caused by the spectral line. 
 11.22 (Sec. 11.7), the voltage onthe reflector ofa reflex klystron ofthetype used asalocal oscillator tunes thetube over a range ofabout 30to70Me/see. Some local oscillators arealso thermally tuned bymeans ofacontrol electrode which isthe grid ofanauxiliary triode. 
 MOMENTS SIMULATION OF A  
 Often a warning receiver on aAirborne Maritime Surveillance Radar, Volume 1 2-20. target might be expected to detect a radar signal at a greater range than the radar could detect the target. It had been suspected for some time that the Germans might introduce ASV listening devices on the U-boats. 
 !RRAY 3YSTEMS AND 4ECHNOLOGY   "OSTON  -!   53!  /CTOBER n    PP n  % "ROOKNER AND *  - (OWELLS  h!DAPTIVE 
 Here, the quadratic curve ﬁtting is taken as an example. ˆedr(fdc)=edr0+edr1(fdc−fdc,cen)+edr2(fdc−fdc,cen)2 ˆe3rd(fdc)=e3rd0+e3rd1(fdc−fdc,cen)+e3rd2(fdc−fdc,cen)2,(13) where fdc,cenis the Doppler centroid of the azimuth center of the scene, the ﬁrst terms of the two expressions are the ﬁxed errors, the second terms are the ﬁrst-order spatial variance errors, and the third terms are the second-order spatial variance errors. In general, the second-order spatial variance error of the derivative of the Doppler rate is too small to be ignored. 
 Even so, the pulse-doppler radar has an advanta&e over the CW  radar in that the detection performance is not limited by transmitter leakage or by signals  reflected from nearby clutter or from the radome. The pulse-doppler radar avoids this  difficulty since its receiver is turned off during transmission, whereas the CW radar receiver is  always on. On the other hand, the detection capability of the pulsc-doppler radar is reduc1.:J  because of the blind spots in range resulting from the high prf. 
 12.17, Prentice-Hall. Inc.,  E~iglewood Cliffs, N. J.. 
 The com- pression ratio is equal to the number of subpulses in the waveform, i.e., the num- ber of elements in the code. Optimal Binary Sequences. Optimal binary sequences are binary sequences whose peak sidelobe of the aperiodic autocorrelation function (see Fig. 
 The approximation cos 0=1allows the use ofunmodulated sweeps in the horizontal direction; this isofnoparticular virtue ifthe resolved- sweep technique isused, but provides aconsiderable saving inconnection with theuseofamodulated carrier. The approximation sino=oallows the use oflinear data transmitters, such aslinear potentiometers and condensers. Since the applications ofFig. 
 TRACKING APERTURE SIZE      
 To an airborne radar, a clutter scatterer appears to have a  radial velocity that differs from the antenna-boresight radial velocity at the same range by  V V V V V Ve r B g g g= − = − = − +cos c os [cos cos( )]α α α α θ0 0 0 = = +V Vx y sin s in θθ222  (3.3) for small values of q  and depression angle f0, where Vx is the horizontal component  of velocity perpendicular to the antenna boresight and Vy is the component along the  antenna boresight. q  is the azimuthal angle from the antenna boresight, or the intersec - tion of the vertical plane containing the boresight with the ground. The corresponding  doppler frequency, when a 0 is a few beamwidths from ground track, is  fV V dx x= ≈2 2 λθλθ sin (3.4) This phenomenon results in a platform-motion clutter power spectrum that is weighted  by the antenna’s two-way power pattern in azimuth. 
 OFF FROM ONE RADAR TO ANOTHER  OR COMMUNICATION TO A MISSILE IN FLIGHT  IS REQUIRED 4HIS IS TYPICALLY THE CASE WHERE A SEARCH RADAR ACQUIRES A TARGET AND QUEUES A PRECI 
 SCAN DOPPLER RADAR DEVELOPMENT CONSIDERATIONS  0ART ))  TECHNOLOGY ASSESSMENT v IN ST #ONF 2ADAR -ETEOROL !-3  "OSTON    PP n  0 , 3MITH  h!PPLICATIONS OF RADAR TO METEOROLOGICAL OPERATIONS AND RESEARCH v  )%%% 0ROC    VOL   PP n     # , (OLLOWAY AND 2 * +EELER  h2APID SCAN DOPPLER RADAR THE ANTENNA ISSUES v IN  TH #ONF  ON 2ADAR -ETEOROL  !-3  .ORMAN    PP n   , *OSEFSSON  h0HASED ARRAY ANTENNA TECHNOLOGY FOR WEATHER RADAR APPLICATIONS v IN  TH #ONF  ON 2ADAR -ETEOR OL  !-3  0ARIS    PP n  2 * +EELER  h7EATHER RADARS OF THE ST CENTURY A TECHNOLOGY PERSPECTIVE v IN  TH #ONF ON  2ADAR -ETEOROL  !USTIN  !-3    PP n  0 -EISCHNER  # #OLLIER  ! )LLINGWORTH  * *OSS  AND 7 2ANDEU  h!DVANCED WEATHER RADAR SYS 
 11.5. The carrier  frequencies of any echo pulses returned to the radar will be determined by the elevation angle  of the targets. The receiver employs a bank of filters, each tuned to a different carrier frequency  which in turn corresponds to a different angle. 
 Sens. , vol. 36. 
 LO rejection typically imposes tight filter rejection  requirements on the RF filters, and for wide-tunable ranges, switched filters are  often required.FIGURE 6.25  Frequency multiplier operationxM A(t)ej[wt+f(t)]A(t)ejM[wt+f(t)] ch06.indd   50 12/17/07   2:04:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 Rept. 5849-1-F, April 1964. 54. 
 Figure 8.11 is a plot of peak time sidelobe level as a function of the  time sidelobe control factor k, for various TB products, for this NLFM waveform. FIGURE   8. 10 Ambiguity function of an LFM waveform compared to a symmetrical NLFM waveform LFM Ambiguity Function Symmetr ic NLFM Ambiguity Function1 11 1−1 −1−1 −10 00 0 f/Bf/B t/tpt/tp §  Courtesy of Edwin M. 
  
 TIONS BETWEEN THE INTERNAL MOTIONS AND HYDROMETEOR GROWTH PROCESSES IN THE STORMS   AND STUDIES OF ELECTRIC CHARGE SEPARATION IN CLOUDS "ROOK AND +REHBIEL WERE AMONG  THE FIRST TO DISCUSS A VERY RAPID 
 Therefore, the use of 40 dB Taylor weighting based on a simplified model which assumes a rectangular amplitude spectrum and a parabolic phase spectrum (that can be matched by the linear group delay) fails to achieve a —40 dB sidelobe level. Further degradation results when there is a doppler shift. Figure 10.17 plots the peak sidelobe level versus the target's doppler1 2 3 4 5 6 7 8Weighting function Uniform Dolph-Chebyshev Taylor (n = 8) Cosine-squared plus pedestal:^ + (1 - H) cos2 (ir/75) a. 
 clrra\, (Fig. 8.18) in contrast to a phase-pltase array which uses phase  stlifters to steer in both angular coordinates. The antenna may be considered as a number of  frequency-scan arrays placed side by side. 
 Large pa products require waveforms long in duration and of  wide bandwidth.  The poorest waveform for obtaining accurate time-delay and frequency measurements  simultaneously is the one for which pa = n. It may be shown that this corresponds to the  gaussian-shaped pulse. 
 J. Gawronski, and H. Goldie: L-Band Receiver Protection, Microwave  J., vol. 
 This necessitates a sufficiently  large aperture at the lowest frequency to be transmitted. To achieve small antenna  dimensions and high gain, therefore, requires the use of a high carrier frequency,  which may not penetrate the material to sufficient depth. When selecting equipment  for a particular application, it is necessary to compromise between plan resolution, size  of antenna, the scope for signal processing, and the ability to penetrate the material. 
 Burghart, “Doppler radar sampling limitations in convec - tive storms,” J. Atmos. Ocean. 
 STATE TRANSMIT 
 Asaresult ofthevariety ofoperational demands alarge number oftypes oftubes have been developed. The next few sections describe some oftheir salient features. 13.1. 
 The chief scatterers are those components of the sea that are  of a dimension cotllparable to the radar wavelength (Bragg scatter). Scattering in this region  ic s~tnilar to that froin a rough surface.  C  Table 13.1 World hleteorological Organization sea  state  Wave height  Sea state Feet Meters Descriptive term  0  0  !--If  2 -4  4 -8  8 -13  1 3 - 20  20 30  30 -45  over 45 0  0 -0.1  0.1 0.5  0.6- 1.2  1.2-2.4  2.4-4.0  4.0-6.0  6.0 9.0  9.0-14  over 14 Calm, glassy  Calm, rippled  Smooth, wavelets  Slight  Moderate  Rough  Very rough  High  Very high  Phenomenal  RADAR CLUTTER 475 10 XANDL IVERT.ANOH7 X(HOR.POL) L(HOR.POL.) 220MHz (HOR.POL,) 50MHz(HOR.POL) _l-__~__--,-_ ,I _l _~L.-_-'- __--' 102030405060708090 GRAZING ANGLE(degrees)o -10 -40 -50- -70-60_-20 rn .:~ C) b -30--LL_-~ Figurel.l3Composite of(Todataforaverage conditions withwindspeedsranging from10to20knots. 
 NOISE AND SIGNAL 
     . 
 Thousands oftimes asmuch effort asthat expended onall other forms ofradar put together has gone into the remarkably swift development ofpulse radar since itsorigin intheyears just before World War II. Inpulse radar, the transmitter ismodulated insuch away that it sends outvery intense, very brief pulses ofradio energy atintervals that arespaced rather farapart interms oftheduration ofeach pulse. During thewaiting time ofthetransmitter between pulses, thereceiver isactive. 
 Actually, the most compact airborne microwave radar setproduced during the war was also byfar themost simple tooperate, and itincorporated nearly allofthefeatures mentioned above. This set, designated AN/APS-10, isdescribed in Chap. 15ofthis book. 
 Reprinted in Barton, D. K.: "CW and Doppler Radars," vol. 7, Artech House, Norwood, Mass., 1978, sec. 
 The Taylor aperture illumination has also been applied to syntt~esiring thc: patterns of  circular, two-dimensional It has been widely used as a guide for selecting  antenna aperture illuminations.  When the difference pattern of a monopulse antenna can be selected independently of thc  sum pattern, as in a phased array, the criterion for a good difference pattern is to obtain  maximum angle sensitivity commensurate with a given sidelobe level. Bayliss8%s described  a method for obtaining suitable monopulse difference patterns on this basis. 
 Seasat was designed to measure global ocean dynamic topography, as well  as wave height and surface wind speed. Geosat.  This altimeter’s design71 was patterned closely after that of the Seasat  altimeter. 
 The rolloff is approxi - mated by treating the shadow area A as a uniformly illuminated antenna aperture. The  radiation pattern of this shadow aperture  is equal to the forward-scatter RCS rolloff  when (p − b ) is substituted for the angle off the aperture normal. A sphere of radius  a will roll off 3 dB at ( p − b ) ≈ l /p a, when a/l 1. 
 The radar "uncertainty" relation seems to have the opposite interpretation of the uncer-  tainty principle of quantum mechanics. The latter states that the position and the velocity of  an electron or other atomic particles cannot be simultaneously determined to any degree of  accuracy desired. Precise determination of one parameter can be had only at the expense of the  other. 
 SHAPE FACTOR &OR THE MEASUREMENT OF THE REFLECTIVITY OF RAIN  REFER 
 Consequently, all measurements will be  somewhat in error, with the error being a function of the properties of the atmosphere,  the radar wavelength, and the time allocated to the measurement. The theoretical development of signal estimator statistics is found in Denenberg,  Serafin, and Peach91 for the FFT technique. Doviak and Zrnic ′23 cover the subject quite  completely while Keeler and Passarelli79 provide a good summary of all these estimation  techniques and the respective measurement error expressions. 
 #7 WAVEFORMS ARE OFTEN USED /NE METER ACCURACY AND  METER MINIMUM RANGE IS USUALLY REQUIRED FOR BLIND TANKING (IGH 0OWER 
 Recent advances have dramatically increased the SAR monitoring potential by improving spatial resolution, revisit time, swath width and polarimetric capability. Moreover, the present and forthcoming spaceborne missions, allow SAR imaging at di ﬀerent bands and acquisition modes (e.g., spotlight, wide swath, bistatic, multi-static and geosynchronous). All these advances stimulated the investigation of new processing algorithms, products, and applications able to fully exploit the new sensor capabilities (e.g., wide spectral band, multi-angle view, short revisit time), as well as the large and continuously updated SAR data archives. 
 SEC. 9.14] SCHWA RZSCHILD ANTENNA 295 The transmission line isawaveguide ending inachoke flange attached tothechannel atthepad shown inFigs. 9.19 and 921. 
 GAIN AUXILIARY PERFORMING THE 3,# PROCESSING IN &)'52%   #ONTOUR CURVE OF  *#2 D"  VERSUS THE AMPLITUDE IN NATURAL  NUMBER  ALONG THE HORIZONTAL AXIS  AND PHASE IN DEGREES  ALONG THE VERTICAL AXIS   MISMATCHES OF THE ANALOGUE RECEIVING CHANNELS                   
 The detection becomes even better the more reflected energ y from the  target is received and integrated.  From the Radar equation possibilities for an apparent energy  increase can be seen.  They each exist only for only one pulse. 
 (A loss of from 10 dB to may be  20 dB is not unusual when all radar system loss factors are taken into account.) Equation 1.5 applies for a radar that observes a target long enough to receive n  pulses. More fundamentally, it applies for a radar where the time on target to is equal  to n/fp. An example is a tracking radar that continuously observes a single target for  a time to. 
 Onreception theTRtubesareunfiredandtheechosignalspassthroughtheduplexer and intothereceiver asshowninFig.9.6b.Thepowersplitsequallyatthefirstjunction and becauseofthe90°phaseadvance onpassingthrough theslot,theenergyrecombines inthe receiving armandnotinthedummy-load arm. Thepower-handling capability ofthebalanced duplexer isinherently greaterthanthatof thebranch-type duplexer andithaswidebandwidth, overtenpercentwithproperdesign.A receiver protector, tobedescribed later,isusuallyinserted between theduplexer andthe receiverforaddedprotection. Another formofbalanced duplexer39usesfourATRtubesandtwohybridjunctions (Fig.9.7).Duringtransmission (Fig.9.7a)theATRtubeslocatedinamountbetweenthetwo short-slot hybridsionizeandallowhighpowertopasstotheantenna. 
 8.6. Comparing Hansen's scanning calculation with the single-point calculation, one concludes that 1 dB of improvement is obtained by making a decision at every pulse. The angular error of the beam-splitting procedure is about 20 percent greater than the optimal estimate. 
 Remote Sensing Symp. (IGARSS ’82), IEEE  82CH14723-6, vol. 1, 1982. 
 L. Lewis and F. F. 
 SAND WICH CAN BE THOUGHT  OF AS TWO BACK 
 P. Claasen, and Y . H. 
 TO 
 A second-order correction that has been utilized when changing between  CPIs with different PRIs is to have a transition PRI that is the average of the two PRIs.  With phased array radars, if the beam transition time between CPIs takes longer than a  PRI, it is important to keep the transmitter pulsing at a constant duty cycle during the  transition time. If constant duty cycle cannot be maintained, or when starting to radiate  †  Power conditioners accept either ac or dc input and provide a regulated dc output. 
 Rept. 2226, March 1971. 46. 
 20. D. A. 
 38. Marcus, M. B., and P. 
   PP n  -AY . Ó°£ /Ê,>`>À 7>Ê7°Ê- À>`iÀ 3HRADER !SSOCIATES  )NC 6 iÊÀi}iÀÃ>Ãi .AVAL 2ESEARCH ,ABORATORY Ó°£Ê *, 
 Radar sets ofagiven kind are usually operated atsomewhat different frequencies inorder toavoid mutual interference. Thus, the receiver ofthe beacon has tohave sufficient bandwidth toreceive the interrogating signal from any one ofthe radar sets. For airborne 3-cm radar sets, forexample, the band from 9320 to9430 Me/see was used. 
 The sum beam is used on both trans - mit and receive to detect the target. The difference beam is receive only and provides  angle determination. In most applications, both azimuth and elevation difference beam  ports are implemented. 
 27, p. 384, June 1939. 39. 
 63.Schelonka, E.P.:Adaptive ControlTechniques forOn-Axis Radars,IEEE1975Internatiollal Radar Conference, Arlington, Va.,April21-23,1975,pp.396-401, IEEEPublication 75CHO93!HAES. 64.Clark,B.L.,andJ.A.Gaston: On-Axis Pointing andtheManeuvering Target,NAECON '75Rl.'Cl)rd, pp.163-170. 65.Pollock, E.J.:InLoopIntegration Control (ILIC),Technical Memorandum 118,Feb.I,1976,Air ForceSpecialWeapons Center,Kirtland AirForceBase,NewMexico. 
 M. : Electronic Scanning: Past and Future, Electrortic Scarlrtirtg S!9~npo.sitort. Apr. 
 chap. 37 of" Radar Handbook," M. I. 
 Thus, when STC is used with a cosecant-squared antenna pattern, the  high-angle coverage of the radar is reduced. Targets that are seen at long range and at a  particular height with a cosecant-squared antenna, will be missed at shorter ranges when STC  b used. To incorporate both beam shaping and STC, the pattern must have higher gain at  higher-elevation angles than would a cosecant-squared pattern. 
 The center of the feed is placed at the focus of  the parabola, but the horn is tipped with respect to the parabola's axis. The major portion of  the lower half of the parabola is removed, leaving that portion shown by the solid curve in  Fig. 7.10. 
 A. Weiss: A Switchable Circulator: S-band; Stripline; Remanent; 15  Kilowatts; 10 Microseconds; Temperature Stable, IEEE Trarrs., vol. MTT-14, pp. 
 16. Farnell, E. C.. 
 W.: An Improved Simultaneous Phase Compariscru Guidance Radar, IRE Trans., vol.  ANE-3, pp. 67-70, June, 1956. 
 tained inthe same chassis, though with some crowding, The noise figure ofthis experimental amplifier was 1.6db. The amplifier ismounted ona9+by2+-in. chassis, which permits easy access toallcomponents. 
 In the early versions of the phase-comparison monopulse radar, the angular error was  determined by measuring the phase difference between the outputs of receivers connected to  each antenna. The output from one of the antennas was used for transmission and for provid­ ing the range information. With such an arrangement it was difficult to obtain the desired  aperture illuminations and to maintain a stable boresight. 
 For this reason, protection in the form of ECCM techniques becomes  necessary. ECCM Techniques.  Electronic protection for OTH radar antenna arrays can be  provided in the form of adaptive signal processing in space and time. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.48  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 and  e t Ev vj t kzv ( ) Re( )=− +ω δ (16.26 b) In complex format  E E eh hjh =0δ and E E ev vjv =0δ  If we take d  = dv – dh and set dv = 0 as a reference, we can write  E E e Ehj v v = +− 0 01δ   Thus, for a single wave, we need only have three independent parameters. 
 This is a winter daytime example at a United States east coast location. The three straight lines are estimates of anthropogenic (formerly man- made) noise for three different types of sites. The shape of the anthropogenic curves is described by the equations NQ= - 136 - 12.6 In (/73) residential NQ= - 148 - 12.6 In (/73) rural NQ= - 164 - 12.6 In (/73) remote where the frequency/is in megahertz and In indicates the natural logarithm. 
 {a) Contours  for constant dopppler frequency {velocity); (b) contours for constant time delay (range); (c) composite  surface. {Courtesy S. Applebaum and P. 
 The AGC was engaged when the scanner was stopped and automatically reduced the gain to maintain the signal at a constant level. In addition, the strobe unit provided the timing markers at 3 miles and 1 ½ miles (i.e. 6250 and 3750 ft) for the range lamps on the strobe control unit and the bomb release signal, according to the stick length setting. 
 Such tubes are of high efficiency (40 to  60 percent), relatively low voltage (compared with a linear-beam tube), and of light weight and  small size so as to make them of interest for mobile applications. CF As are capable of broad  bandwidth (10 to 20 percent) with high peak power, but the gain is usually modest. They have  good phase stability, and a number of CF As can be operated in parallel for greater power. 
 (f) The pilot and observer of aircraft ﬁtted with ASV should have visual indications given to them of the ASV beam approach system. (g) Equipment should incorporate anti-jamming devices to enable it to function in spite of enemy attempts to interfere with the performance of the equipment.Airborne Maritime Surveillance Radar, Volume 1 3-2. (h) It should provide, when required, an aural indication of the presence of a target. 
 ,,,,.,-· \  \ /  \ I \-~··  Azimuth angle -degrees Trailing  edge of  horizontal  toil I  Figure 2.17 Comparison of the theoretical and model-measurement horizontal-polarization radar cross  sections of the B-47 medium bomber jet aircraft with a wing span of 35 m and a length of 33 m. Solid curve  is the average of the computed cross sections obtained by the University of Michigan Engineering  Research Institute at a frequency of 980 MHz. Dashed curves are model measurements obtained by the  Ohio State University Antenna Laboratory at a frequency of 600 MHz. 
 M 3POT3!2  STRIP MAP  3CAN3!2  AND  
 pp. 391 J95. Oct. 
 Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 19.6  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 where C (isolated in brackets in Eq. 19.13) is the so called Weather Radar Constant  with Pr expressed in dBm and r in km. 
 In Proceedings of the COMPSTAT’2010, Paris, France, 22–27 August 2010; pp. 177–186. 38. 
 ● After amplification by a receiver and with the aid of proper signal processing, a  decision is made at the output of the receiver as to whether or not a target echo  signal is present. At that time, the target location and possibly other information  about the target is acquired. A common waveform radiated by a radar is a series of relatively narrow, rectan - gular-like pulses. 
 D.C.,Apr.12,1972. 62.Spafford, L.J.;Optimum RadarSignalProcessing inClutter,IEEETrans.,vol.1T-14,pp.734-743, September, 1968. 63.Andrews, G.A.:Airborne RadarMotion Compensation Techniques, Evaluation ofDPCA.NRL Report7426,NavalResearch Laboracory, Washington, D.C.,July20,1972. 
 AN INTRODUCTION AND OVERVIEW OF RADAR  1.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 but also is quite useful as a guide for designing a radar system. The simple form of the  radar equation may be written as  PP G R RArt t e = × ×4 42 2πσ π (1.2) The right-hand side has been written as the product of three factors to represent the  physical processes that take place. The first factor on the right is the power density  at a distance R  from a radar that radiates a power Pt from an antenna of gain Gt. 
 Wasylkiwskyj and W. K. Kahn, “Element patterns and active reflection coefficient in uniform  phased arrays,” IEEE Trans ., vol. 
 Continuous application of drive power is not neecled as in otllcr pllusc sllifters. A  "square" hysteresis loop is desired for silch a phase shifter. The scluareiicss is ~ileitsure~l by tlie  ratio of the remanent magnetization to the saturation magnetization, which with practical  ferrite materials might typically be about 0.7. 
 The lowest sidelobe for  the maximal length sequence is seen from  Figure 8.18 b to be only –14 dB.FIGURE   8. 16 Superposition of the autocorrelation functions for all  possible 13-bit code sequences with the Barker Code highlighted (dark),  shown for zero doppler shift 1 −12 12 0 FIGURE   8. 17 Shift-register generator ch08.indd   18 12/20/07   12:50:12 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Noncoherent AMTI. The noncoherent MTI principle that uses the clutter echo instead of a  coho as the reference signal can also be applied to a radar on a moving platform. Although it is  attractive for operation in aircraft where space and weight must be kept to a minimum, its  MTI performance is limited, as is its ground-based counterpart, by the lack of spectral purity  of the clutter when used as a reference signal, and by the spatial inhomogeneity (or patchiness)  of the clutter. 
 The  array can be triade to siriiultaneously generate many search and/or tracking beams with the  sarne aperture.  Other types of array antennas are possible than the linear or the planar arrangements.  For example, the elements niigttt be arranged on the surface of a cylinder to obtain 360"  coverage (360" coverage may also be obtained with a number of planar arrays). 
 1.1 I.('II<ONl(.Al.l.Y SIEFREII I'IIASEI) ARRAY ANTENNA IN RADAR 341  102. Davies. D. 
  
 Zeng, Z.; Shi, Z.; Xing, S.; Pan, Y. A Fourier-Based Image Formation Algorithm for Geo-Stationary GNSS-Based Bistatic Forward-Looking Synthetic Aperture Radar. Sensors 2019 ,19, 1965. 
 However, radars for the surveillance and tracking of extraterrestrial targets,  such as satellites and spacecraft, might employ the cioppler shift to Ineasure tiirectly tllc  relative velocity, but it is seldom used for this purpose in aircraft-surveillance radars. Instead,  aircraft-surveillance radars use the doppler frequency shift to separate the desired moving  targets from the undesired fixed clutter echoes, as in MTI radars.  Ifthe target can be viewed from many directions, its shape can be determined. 
 T. Fujita: The Joint Airport Weather Studies (JAWS) Project, Bull. Am. 
 The larger tlie value of P2, the tliorc  accurate will be the range ~~ieasurenier~t.  Examples of tirne-delay (range) accuracy. The computation of P2 for a perfectly rectangular  pulcc orie with 7ero rise titile anti zero fall tirne-results in /I2 = co. 
 (Tile :tttentl;~tioti in rain. Iiowcver. is still large.) Thus laser radars operating in the  infrared and visible rcgiolis actiieve-tI~c ;lrIvantagcs of liigh angular resolution, wide bandwidth,  and doppler frequency sensitivity without the accompanying disadvantage of high attenuation  as expericficed ill the subniillinicter region. 
 Multiple, indepettder~t beants. A single aperture can generate many simultaneous independent  beams. Alternatively, the same effect can be obtained by rapidly switching a single beam  through a sequence of positions. 
 386 THEMAGNETRO.V ANDTHEPULSER [SEC. 10.11 inrate ofrise orinflatness oftop. Wider-range transformers will be practical only when higher permeability cores and stronger insulation with lower dielectric constants areavailable. 
 DIMENSIONAL SYSTEMS  HAVE BEEN USED  TO DEFINE BISTATIC RADAR OPERATION n ! POLAR COORDINATE SYSTEM IS ALSO SHOWN IN  &IGURE  4HE R   P   COORDINATES ARE LOCATED ON THE BISTATIC PLANE WITH ORIGIN AT THE  MIDPOINT OF THE BASELINE )T IS USEFUL FOR PLOTTING  OVALS OF #ASSINI SEE 3ECTION    AND IS DETAILED IN 7ILLIS /N OCCASION  THE INCLUDED ANGLES  P4g AND P2g ARE USED TO  DEFINE TRANSMITTER AND RECEIVER LOOK ANGLES IN THE BISTATIC TRIANGLE  SUCH THAT  P4g   P2g    A    )N THIS CASE   P4g    n P4 AND P2g      P2 CAN BE USED TO TRANSFORM NORTH 
 Tsandoulis, G. N.: Tolerance Control in an Array Antenna, Microwave J., pp. 24-35, October 1977. 
 ING AND RADAR ABSORBERS  3HAPING IS THE SELECTION OR DESIGN OF SURFACE PROFILES SO THAT  LITTLE OR NO ENERGY IS REFLECTED BACK TOWARD THE RADAR "ECAUSE TARGET CONTOURS ARE DIF 
 UCTS OF THE BASIC DETECTION MISSION &)'52%   A  4EMPORAL FADING AND  B  DISTRIBUTION PROPERTIES OF THE TARGET  CLUTTER PEAKS  AND NOISE  FEATURES IN THE DOPPLER SPECTRUM OF &IGURE   COMPUTED FROM AN EXTENDED DATA SEQUENCE. Óä°xÓ  2!$!2 (!.$"//+  !T PRESENT  THE MOST POWERFUL TOOLS FOR DEALING WITH ADDITIVE INTERFERENCE  AS WELL  AS SOME CLASSES OF SPREAD 
 A so-called four-lobed pattern can be used for main-beam interference cancel - lation.103,104 The use of low-gain auxiliary antennas joined to high gain beams allows  the contemporaneous cancellation of sidelobe and main-beam interferences. Target DoA Estimation in Presence of Sidelobe and Main-Beam Interferences.    Phased-array radars are required to detect, locate, and track targets in the presence of  natural interference and jamming. 
 The antenna elements were spaced at a half wavelength and assumed to be omnidirectional. The clutter model was assumed to be homogeneous. The improvement factor is based on the fully adapted weights. 
 The expression for the doppler frequency shift given previously  hy Eq. (J.2) is an approximation that is valid for most radar applications. The correct expres­ sion for the frequency f • from a target moving with a relative velocity v, when the frequency f  is transmitted is21 23• 70  (* = r (l + lJ/c)  · · (1 -l'/c) (3.9) . 
 The Royal Aircraft Establishment (RAE) compiled a schedule of standard dimensions for ASV units, plugs, sockets and cables, which would make them easier to installand maintain. It was decided that the new radar would have an indicator unit separate from the receiver, with selectable range scales of 10, 40 or 100 miles. The radar would have its own power supply and generate 7 kW peak RF power. 
 &IX IS NOT USED IN A MODERN RADAR  ESPECIALLY ONE THAT EMPLOYS DOPPLER PROCESSING THUS  IT IS NO LONGER OF INTEREST IN MANY RADAR APPLICATIONS /THER SPECIAL PROCESSING CIRCUITS CAN BE USED IN THE RADAR TO AVOID SATURATION  IE   FAST 
 COST POSITION REFERENCING SYSTEMS FOR USE WITH RADAR FOR SUBSURFACE SURVEY TECHNIQUES ARE NOW AVAILABLE )T IS IMPORTANT THAT DATA CAN BE RELATED TO A TRUE GEOGRAPHIC REFERENCE PARTICULARLY WHEN FILED ON DIGITAL MAPPING  SYSTEMS AND USED TO DEFINE AREAS OF SAFE WORKING !NOTHER CONSIDERATION IS THE PLANE OF POLARIZATION OF THE ELECTROMAGNETIC ENERGY  &OR TARGETS WITH ONE LARGE AREA DIMENSION SUCH AS A PIPE  THE RADAR CROSS 
 SEC. 115] DUPLEXING ANDTRSWITCHES 409 The practical method ofaccomplishing this impedance transformation isbymeans ofaresonant cavity. Figure 11.15 shows asection through a1B27 TR tube and associated cavity, with input and output couplings. 
 Tech. Kept. 77044, Mar. 
 For given tube types and supply potentials, the time interval tl–tzisprimarily determined by RZCZ,and the time interval tz-t,’byRICI;these furnish convenient constants bymeans ofwhich control ofthetime intervals can beexerted. I The multivibrator can beused asacompletely free oscillator, oritcan be synchronized bysupplying itwith asine wave orapulse train atahigher frequency than that ofthenatural oscillation. Figure 13.14 shows asingle-stroke or“flip-flop” multivibrator. 
   v  &INAL 2EPT  .AVY #ONTRACT ./7 
 ING A  MAXIMUM TARGET SPEED AND MANEUVER CAPABILITY  B  RADAR BEAMWIDTH BEAM COULD BE SPOILED   C  RANGE OF THE RADAR TRACK  AND D  ACCURACY OF PREDICTED POSITION )F A PULSE DOPPLER DWELL IS REQUIRED TO UPDATE THE TRACK IN CLUTTER  THE WAVEFORM SHOULD BE SELECTED TO PLACE THE TARGET NEAR THE CENTER OF THE AMBIGUOUS RANGE 
 GROUND ECHO  16.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Figure 16.14 b shows an antenna pattern that takes better advantage of the possibili - ties of range measurement. A fan beam is used to illuminate a narrow strip along the  ground, and the range resolution permits separating the returns from different angles  by the time they return. This technique is especially effective at angles away from the  vertical, for the resolution near the vertical is much poorer than near grazing. 
 &#(&#&%$' #"  "''"(' #"  '' #" (# " ) %#"!"'     %% "  '!#&$ % &)'52%  !0- SUBMODEL REGIONS        
 However, there is avertical dimension limitation in the case of sloping surfaces or steppedsurfaces. In this case, only the projected vertical area lying within thedistance equivalent of the pulse length can return echoes at any instant. Aspect The aspect of a target is its orientation to the axis of the radar beam. 
 The *In a private communication to the author in 1963. tBy M. I. 
 I EEE, vol. 56, -pp. 1940- 195 1, Novelnber, 1968. 
 tenna although separate transverse dipole or loop antennas have been employed to avoid a null in the forward direction. The principal problems with the device are those associated with requirements of small size, long shelf life, low cost, and reliability under high acceleration. Be- cause of the very light weight of all solid-state circuitry with integrated compo- nents, complex circuits may be built that will allow proximity fuzes to withstand accelerations in excess of 100,000 g. 
 WATER SURFACES WHEREAS THE 4)2%- MODEL IS BASED UPON KNIFE EDGE DIFFRACTION TECHNIQUES  MAKING THE 4)2%- MODEL INAPPROPRIATE FOR OVER 
 DOMAIN ANTENNA RESPONSE IS SIMILAR TO A SECOND  DERIVATIVE GAUSSIAN SIGNAL )T CAN BE SEEN THAT MOST OF THE INTERNAL REFLECTIONS HAVE BEEN SUPPRESSED 4HE RATE OF DECREASE FOR THE UNWANTED RINGING IS BE TTER THAN  D"NS 4HE  6372 WAS BETTER THAN  FROM  -(Z TO  '(Z 4HERE ARE MANY CONFIGURATIONS OF ANTENNA THAT CAN BE USED CROSSED DIPOLES AND  PARALLEL DIPOLES ARE THE MOST POPULAR 4HE MAIN REASON FOR THE USE OF TWO ANTENNAS IS THAT 42 SWITCHES THAT ARE FAST ENOUGH FOR '02 ARE NOT YET AVAILABLE Ó£°nÊ -  Ê  Ê  
   PP n    2 % +ALMAN  h! NEW APPROACH TO LINEAR FILTERING AND PREDICTION PROBLEMS v  * "ASIC %NG !3-%  4RANS  SER $   VOL   PP n    2 % +ALMAN AND 2 3 "UCY  h.EW RESULTS IN LINEAR FILTERING AND PREDICTION THEORY v  * "ASIC %NG  !3-% 4RANS  SER $   VOL   PP n  . Ç°xÈ  2!$!2 (!.$"//+   3 "LACKMAN AND 2 0OPOLI   $ESIGN AND !NALYSIS OF -ODERN 4RACKING 3YSTEMS   "OSTON !RTECH     2 ! 3INGER  h%STIMATING OPTIMAL TRACKING FILTER PERFORMANCE FOR MANNED MANEUVERING TARGETS v  )%%% 4RANS  VOL !%3 
 HALF THE RESIDUE OF TIME JITTER  AND   ) " LOGT T$07D"    WHERE $07  IS PULSE 
 These are called polyphase  code^.'^.^' The time  sidelobes of a polyphase code can be lower than those of the binary phase-coded waveform of  similar However, the performance of polyphase codes deteriorates rapidly in the  presence of a doppler-frequency shift and therefore they have been limited to situations where  the doppler is negligible.  Other binary coding met hods that have been considered for pulse compression include :'  (I) compound Barker codes for obtaining longer codes from the Barker series by coding seg-  ments of one Barker code with another Barker code (a length 13 Barker code compounded  within another length 13 code gives a pulse-compression ratio of 169 and a peaJ sidelobe of  - 22.3 dB); (2) code sequencing 018 successive PRF periods, in which a different code is used for  each transmission to produce random sidelobes which when N pulses are added to produce a fi improvement in mainlobe-to-sidelobe amplitude ratio, where N is the number of se-  quences employed; and (3) complementary codes in which a pair of equal-length codes have the  property that the time sidelobes of one code are the negative of the other so that if two codes of  a complementary pair are alternated on successive transmissions, the algebraic sum of the two  autocorrelation functions is zero except for the cental peak.36-37  A pulse burst is a waveform in which a series of pulses are transmitted as a group before  any of the echo signals are received. It is used to obtain simultaneous range and doppler-  velocity resolution when the minimum range is relatively long; as for radars whose targets are  extraterrestrial, such as satellites and ballistic missiles. 
 TOR &OR A DEDICATED TRANSMITTER  THE PROCESS CAN BE REVERSED FIX THE TRANSMIT BEAM AND SCAN THE RECEIVE BEAM 4HIS REMEDY INCREASES THE SURVEILLANCE FRAME TIME BY THE NUMBER OF REQUIRED BEAM STEPS AND IS USUALLY NOT ACCEPTABLE FOR LARGE AREA SURVEIL 
 The frequency range over  which the antenna must operate and the VSWR that can be accepted also determine how far  the beam can be scanned. With a scan capability of ± 60°, a minimum of three planar aper­ tures, or faces, are required to cover the hemisphere. But when other factors are considereJ,  more than three faces are usually desired. 
 When the target lies in the nulls, no echo signal is received.  The angle (in radians) of the first (lowest) lobe is approximately equal to A/4ha. If low-  angle coverage is desired, the radar antenna height should be high and the wavelength of the  radiated energy small. 
 DIRECTIVE 
 Abbott, and  T. J. Killpack, “Orbital radar evidence for lunar subsurface layering in Maria Serenitatis and  Crisium,” J. 
 These measurements areinsubstantial agreement with Eq, (32). Introduction ofEq. (32) into Eq. 
 Theholesandslotsfunction astheresonant circuitsandserveapurpose similartothatofthe lumped-constant LCresonant circuits usedatlowerfrequencies. Theholescorrespond, <.1 roughly, totheinductance L,andtheslotscorrespond tothecapacity C.Inthedesiredmode ofoperation (theso-called 1tmode)theindividual C'sandL'sareinparallel, andthefrequency ofthemagnetron isapproximately thatofanindividual resonator. Thecathode (4)isafat cylinder ofoxide-coated material. 
 (ILL  )NC       PP n  ' 7 3TIMSON   )NTRODUCTION TO !IRBORNE 2ADAR   ND %D -ENDHAM  .* 3CI4ECH 0UBLISHING  )NC     PP n  0 , "OGLER   2ADAR 0RINCIPLES WITH !PPLICATIONS TO 4RACKING 3YSTEMS   .EW 9ORK *OHN 7ILEY   3ONS  )NC    PP n  2 ! $ANA AND $ -ORAITIS  h0ROBABILITY OF DETECTING A 3WE RLING ) TARGET ON TWO CORRELATED  OBSERVATIONS v  )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS   VOL !%3 
 The echo not only indicates that a target is present, but the time that elapses between the  transmission of the pulse and the receipt of the echo is a measure of the distance to the target.  Separation of the echo signal and the transmitted signal is made on the basis of differences in  time.  The radar transmitter may be operated continuously rather than pulsed if the strong  transmitted signal can be separated from the weak echo. 
 INVARIANT SCANNING 4HE BEAMS MAY BE SELECTED THROUGH A SWITCHING MATRIX REQUIRING  -  
 A singl~ sweep on an A-scope might appear as in  Fig. 4.Ja. This sweep shows several fixed targets and two moving targets indicated by the two  arrows. 
 The coherent MTI and the pulse-doppler radar make use of the phase fluctuations  in the echo signal to recognize the doppler component produced by a moving target. In these  systems, amplitude fluctuations are removed by the phase detector. The operation of this type  of radar, which may be called coherent MT/, depends upon a reference signal at the radar  receiver that is coherent with the transmitter signal. 
 This function is usually implemented in digital signal processing. Receiver Filtering.  Filtering is required at various points throughout the receiver  chain including RF, IF, baseband if used, digital filtering prior to decimation (reduc - tion of the sample rate), and as an integral part of I/Q generation. 
 M. Hall and W. W. 
 PULSE  FLUCTUATING TARGET   .     M    REFERENCE CELLS  AND  0FA    
 CUITRY FROM DAMAGE DUE TO HIGH POWER THAT MAY OCCUR EITHER FROM LEAKAGE DURING  TRANSMIT MODE OR AS A RESULT OF INTERFERENCE FROM ANOTHER SYSTEM SUCH AS A RADAR AT CLOSE RANGE &RONT 
 the echo from a target is frequency modulated when illuminated by such a frequency-scanned  beam. Pulse-compression filtering (similar to chirp) can be used to achieve a range resolution  equal to the reciprocal of the one-way group delay along the dispersive delay line (snake feed)  feeding the frequency-scan array.  There is another array antenna technique called withi11-p11/se sca1111i11g that is different  from the frequency scan technique described above. 
 58-59, June, 1974.  22. Hines, M. 
 W.: A Broadband Microwave Noise Source, Bell System Tech. J., vol. 211, pp. 
 10, no. 10, pp. 165 - 166, May 16, 1974. 
 [ CrossRef ] 4. Schuler, D.L.; Lee, J.S.; Grandi, G.D. Spiral Eddy Detection Using Surfactant Slick Patterns and Polarimetric Sar Image Decomposition Techniques. 
 Inaddition toshiftingthecenterfrequency oftheclutter,itsspectrum isalsowidened. An approximate measure ofthespectrum widthcanbefoundbytakingthedifferential ofthe doppler frequency.td =2(v/l)cos0,or 4fd=2;sin0/10 (4.36) wherev=platform speed,l=wavelength, and0istheazimuth anglebetween theaircraft's velocity andthedirection oftheantenna beam.(Thenegative signintroduced bydifferentia­ tionofcos0isignoredandtheelevation angleisassumed tobezero.)Ifthebeamwidth is. take11 as AO, tlien A!, is a rneasttre of the widtli of doppler frequency spectrum. 
 PHONE  TOWER TRANSMITTERS 4HE FORMER CAN YIELD EQUIVALENT MONOSTATIC DETECTION RANGES OF AIR TARGETS OF n KM THE LATTER  n KM  WHICH IS OF THE ORDER OF THE CELL 
 27.'pp. 1138-1147, November, 1970.  107. 
 OF 
 Care must betaken inthe latter that ‘‘droop” intheswitching-off pulse does not allow the grid to gotoofarpositive when the clamp isclosed, forthis can produce over- shoot through grid-cathode diode action. Square-wave droop can also cause overshoot inthepositive clamp iftheclamping isnot tight. The relative merits ofthe various single-sided clamps depend upon theuses towhich they aretobeput, thetype ofswitching source avail- able, and soon. 
 TION ON THE IMPROVEMENT FACTOR DUE TO TIME JITTER IS  )T   LOG;   =T$D"  4HIS  LIMIT ON THE IMPROVEMENT FACTOR IS BASED ON A #7 TRANSMITTER PULSE AND ON THE ASSUMP 
 The number of resolution cells can be materially  reduced if the narrow angular resolution cell of a pencil-beam radar is replaced by a beam in  which one dimension is broad while the other dimension is narrow, that is, a fan-shaped  pattern. One method of generating a fan beam is with a parabolic reflector shaped to yield the  54INTRODUCTION TORADAR SYSTEMS Insteadofmodulating theprf,otherschemes thatmightheemployed to"mark"SUCCl:S­ sivepulsessoastoidentifymultiple-time-around echol:sincludechanginglhl: pulsl:amplitude, pulsewidth,frequency, phase,orpolarization oftransmission frompulsetopulse.Genaally, suchschemes arenotsosuccessful inpractice asonewouldlike.Oneofthefundamental limitations isthefoldover ofnearbytargets;thatis,nearbystronggroundtargets(clutter)can bequitelargeandcanmaskweakmultiple-time-around targetsappearing atthesameplace onthedisplay. Also,moretimeisrequired toprocessthedatawhenresolving ambiguities. 
 pp.48-55.January, 1977. 27.Brigham, E.0..andR.W.Morrow: TheFastFourier Transform, IEEESpectrum, vol.4,pp.63-70, Decemher, 1967. lX.Rahiner. 
 He considers the projection of the points on a hemisphere onto a plane  (Figure 13.9): the axes of the plane are the direction cosines cos ax, cos ay. For any  direction on the hemisphere, the direction cosines are  cos s incos cos s insinα φ α φx y= =q q  The direction of scan is indicated by the direction cosines cos axs, cos ays. Here  the plane of scan is defined by the angle f measured counterclockwise from the cos  ax axis and is given by  φα α=−tancos cos1 ys xs  The angle of scan q  is determined by the distance of the point (cos axs, cos ays) from  the origin. 
 The chief reason for the dual channels in this radar is to  provide greater availability of the radar. A failure in one channel does not require the radar to  shut down. The radar operhtes with a single channel while repairs are being made. 
 SAR polarimetry to observe oil spills. IEEE T rans. Geosci. 
 is a hybrid device that combines semiconductor and vacuum-tube technology. It contains  a heated cathode that generates an electron beam which strikes a semiconductor diode at high . 218 INTRODUCTION TO RADAR SYSTEMS  energy (typically 10 to 15 keV). 
 4  Bipolar video: return from single transmitter pulse POINT TARGETS FIGURE 2.5  Bipolar video: from consecutive transmitted pulses ch02.indd   5 12/20/07   1:42:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 8.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 P(n,k) Polyphase Codes. 
 " /9Ê " /," Ê­-6 ® )N THE MID 
 SOLID-STATE TRANSMITTERS  11.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 ● Phase errors in cascaded stages simply add. However, it may also be possible to  arrange them to cancel by proper phasing of power supply ripples for different  stages. Similarly, in a stage with N modules in parallel, each with its own high- frequency power-conditioned power supply, the overall phase ripple can usually be  assumed to be reduced by a factor equal to the square root of N if the power supply  clocks are purposely not synchronized. 
 (/2):/. 2!$!2   Óä°Ç£ -UCH OF THE DISCUSSION RELATING TO SKYWAVE RADAR CARRIES OVER DIRECTLY TO (&372   BUT THERE ARE A FEW AREAS WHERE DIFFERENCES ARE SIGNIFICANT u 4HE ANTENNAS MUST BE DESIGNED AND POSITIONED TO ACHIEVE HIGH EFFICIENCY IN  COUPLING TO THE SURFACE WAVE MODE %XPERIMENTS HAVE SHOWN THAT HIGHER FIELD STRENGTHS ARE GENERATED AT OVER 
 J. W., R. F. 
 pp. 339-345. May. 
 229–243, 1988. 112. T.-K. 
 TION v IN !PPLICATIONS OF 3PACE 
 437-466, May, 1965.  7. Fry. 
 Possible reasons include a poor set-up of the radars in [ 15] and reduced losses with the waveguide feeds used in ASV Mk. IIIC (see discussion on ASV Mk. VIC in chapter 4). 
 143. S. H. 
 70. J. L. 
 zero crossings of the received waveform. The zero­ crossings detector destroys amplitude information. If the exact phase of the echo carrier were  known, it would be possible to design a detector which makes optimum use of both the phase  information and the amplitude .information contained in the echo signal. 
  
 Atthe ground radar station, signals inthevarious altitude intervals can besorted outand displayed separately fortransmission to aircraft using the system. The transponder also increases therange of the radar equipment and, ifareply frequency different from thetrans- mitter frequency ofthe radar isused, eliminates difficulty from ground echoes which might interfere with seeing low-flying aircraft. Figure 7.18 ~holl-s aTeleran display asitmight appear toapilot flying at11,000 ft. 
 4.32, which plots the improvement  factor for two-pulse arid tllree-pulse cancelers witti various levels of limiting.53 The abscissa  applies to a gaussian clutter spectrum that is generated either by clutter motion with standard  deviation rr,, at a wavelengtli R and a prf .f,, or by antenna scanning modulation with a  MTIANDPULSE DOPPLER RADAR137 60 50 mu I E40- u l? C Q) E Q)30>0 0.E 20i--~rl 0011()- nB=lOa nB=50 a-'I -'---_-'I---'__-'------'_-'- ..LL--'--'--'--_-'- __---L_---'.__-' 0001 Fi~ure4.32Effectoflimitlevelontheimprovement factorfor(a)two-pulse delay-line canceler and (b)three-pulse delay-line canceler.elL=ratioofrmsclutterpowertolimitlevel.(FromWardand Shrader,s3 Courtesy IEEE.) However, whentheMTIimprovement factorisnotgreatenough toreducetheclutter sufficientlYAhe clutterresiduewillappearonthedisplayandpreventthedetection ofaircraft targetswhosecrosssections arelargerthantheclutterresidue. Thiscondition maybepre­ ventedhysettingthelimitlevelLrelative tothenoiseN,equaltotheMTIimprovement factorI;orLIN=I.Ifthelimitlevelrelativetonoiseissethigherthantheimprovement factor.clutterresidueobscures partofthedisplay.Ifitissettoolowtheremaybea"black hole"effectonthedisplay. Thelimiterprovides aconstant falsealarmrate(CFAR) andis essential tousableMTIperformance.5o Unfortunately, nonlinear devices suchaslimiters haveside-effects thatcandegrade performance. 
 ,-.-,---,8 %6\ .\// bl\\Roll , \ \—————— ——— - \, / -—- -.=’. (A.‘-:~B~%’ Wavefronts (a) (b) FIG.9.34.—Reflector rollscanner, lent simple antenna isapolystyrene lens placed between parallel trape- zoidal conducting plates and fedbyawaveguide atone edge oftheplates (Fig. 934a). 
 A more suitable reciprocal device that overcomes the limitations of previous recipro-  cal ferrite phase shifters in the dual-n~ode phase shifter based on the principle of the Faraday  rOtor.2s.33.3s-37 It is competitive with the toroid phase shifter, especially at the higher niicro-  wave frequencies. d  In the dual-mode phase shifter the linearly polarized signal in rectangular waveguide at  the left-hand port in Fig. 8.13 is converted to circi~lar polarization by a nonreciprocal circt~lar  polarizer (a ferrite quarter-wave plate). 
 REGION EXPANSIONS FOR PREDICTING THE 2#3 OF ELECTRICALLY SMALL OBJECTS HAVE LAPSED INTO DISUSE 3EVERAL APPROXIMATE METHODS HAVE BEEN DEVISED FOR THE OPTICS REGION  EACH WITH ITS  PARTICULAR ADVANTAGES AND LIMITATIONS 4HE MOST MATURE OF THE METHODS ARE  GEOMETRIC  OPTICS AND  PHYSICAL OPTICS  WITH LATER METHODS ATTACKING THE PROBLEM OF DIFFRACTION  FROM EDGES AND FROM SHADOW BOUNDARY FIELD DISCONTINUITIES 7HIL E THE GENERAL ACCU 
 ..... 8  BASIC RF PULSED RADAR SIGNALS  ................................ ..................... 
 28. E. F. 
 K. S. Kelleher, and H. 
 (ALL    )NC    3 0 !PPLEBAUM  h!DAPTIVE ARRAYS v )%%% 4RANS  VOL !0 
 In most instances, these sources are mov - ing at a speed determined by the mean wind aloft and have a mean doppler frequency  significantly different from that of the surface clutter. If the MTI filter is tracking the  surface clutter, the spectra of the sources with a different mean doppler frequency lie  in the passband of the MTI filter. A 20-kt differential in a UHF system corresponds  to 30 Hz, which would generally be outside of the traditional AMTI notch filter in a  300 Hz PRF system. 
 LOOP CHARACTERISTIC OF A SERVOSYSTEM IS UNITY AT ZERO FREQUENCY   TYPICALLY REMAINING NEAR THIS VALUE UP TO A FREQUENCY NEAR THE LOW 
 67. R. C. 
 TACCAR removes the average compo- nent of platform motion perpendicular to the aperture. Wheeler Laboratories (now Hazeltine Corporation) developed the Coincident Phase Center Technique (CPCT)15 to remove the spectral spread due to the velocity component perpen- dicular to the aperture and due to the component parallel to the aperture. Re- moval of the component parallel to the aperture uses the DPCA pattern synthesis technique described in Ref. 
 The  S band VA-87, a four-cavity klystron amplifier, has a synchronously tuned half-power band-  width of 20 MHz and a gain of 61 dB. When tuned for maximum power the bandwidth is  irlcreased to 27 M1I7. arid the gain reduced to 57.6 dB.9 By stagger tuning the various cavities  the half-power bandwidth can be increased to 77 MHz (about 2.8 percent bandwidth), but  with a corlcurrerit decrease in gain to 44 dB. 
 This configuration has been called a mirror scan antenna (by the  Naval Research Laboratory), polarization twist Cassegrain and pat plate Cassegrain (by  Westinghouse Electric), and a parabolic'reJlector with planar auxiliary mirror (by Russian  authors13'). The parabolic reflector is made up of parallel wires spaced less than a half-  >,  242INTRODUCTION TORADAR SYSTEMS Figure7.12Polarization-twisting Cassegrain antenna. Aperture blocking bythesubreflector isreduced with thisdesign..j Subreflector with polarization ­ dependent surfaceVertical polorilotionMainreflector with .ypolarization twister V'{/(twistreflector) ~ ~ f f 'I 'I 'I ~ ~ Minimum totalaperture blocking occurswhentheshadows produced bythesubrd1ector and thefeedareofequalarea.19Aperture blocking islessseriouswithnarrowbeamwidths and smallIIDratios. 
 The reflected  energy is also simultaneously received on other arrays that are separated in the east-  west direction by various distances (baseline). Signals from any two can be added   to form a baseline pair. The baseline receivers employ triple frequency conversion  where the phase difference of the signals received by the antenna pair is preserved in  a 1000-hertz difference frequency [called a 1 kHz phase signal in the figure]…  There  is a radio receiver and consequently a 1000-hertz phase [signal] for each baseline pair   (12 east west and 3 north south). 
 15.lib. Note that the clutter in Fig. \5.\lb is very spotty in character, including the strong fixed- point targets and returns from extended targets. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation. 26.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 ships were 500 nautical miles SW of Kiska during the firing. 
 ING OF THE ENVIRONMENT  RADAR -ULTIFUNCTION RADAR )F EACH OF THE ABOVE RADARS WERE THOUGHT OF AS PROVIDING SOME  RADAR FUNCTION  THEN A MULTIFUNCTION RADAR IS ONE DESIGNED TO PERFORM MORE THAN ONE SUCH FUNCTIONUSUALLY PERFORMING ONE FUNCTION AT A TIME ON A TIME 
 128. "Effective Utilization of Optics in  Radar Systems." pp 128-143. 1977. 
 Delay times of this  magnitude cannot be. achieved with practical electromagnetic transmission lines. By convert­ ing the electromagnetic signal to an ·acoustic signal it is possible to utilize delay lines of a . 
    
 STEERED  THE FORE AND AFT FOOTPRINTS WERE MISREGISTERED DUE TO %ARTH ROTATION  WHICH REDUCED THE USEFUL SWATH AT LOWER LATITUDES TO ABOUT  KM 4HE VALUE OF  + P VARIED FROM  TO  OVER THE OCEAN UNDER  MODERATE TO HIGH SEA STATES  BUT DEGRADED TO  FOR LOWER WIND SPEEDS AND TO  FOR VERY LOW BACKSCATTER FROM NON 
 M. Shoemaker, “The Clementine bistatic radar experiment,” Science , vol. 274,   pp. 
 a Sawtooth modulation, b Triangular modulati on, c Sinusoidal modulation   The figure shows the transmitting signal in the upper lines, in the middle row the transmitting  and receiving signals, and on the bottom the difference from both.  The transmitting frequency is, as follows, time- dependent for the sawtooth modulation.   € fT=f0+Δf⋅t T (7.5)  For the symmetric triangular modulation results in:   € fT=f0+Δf⋅2t T (7.6)  In the following the sawtooth modulation will be further considered. 
 Airorwatercooling mightbeneeded. Theferritematerial maybebiased,asforexample alatching-ferrite circulator, topermit thehandling ofhigherpower.45Sincethelatching-ferrite receiver protector isundamaged by highpowerwhenineitherstate,protection fromnearbytransmitters canbehadbyinserting a passiveTR-lil]liter following theferrite.. RECEIVERS, DISPLAYS, AND DUPLEXERS 365  Antenna  (radioactive - limiter  Circulator primed)  L J Y  Passive TR-l~rniler Receiver  Figure 9.9 <'irculator ant! receiver protector. 
 low elevations the two signals from the vertical and slant beams might bedisplayed soclose together that noheight canbefound. Thk problem iseliminated byintroducing afixed separation of10°between thebeams, sothat there isa10°separation between thesignals even from atarget atzero altitude. The indicator isdesigned around the general principle ofaB-scope inthat range ispresented against angle. 
 I RE, vol. 41, pp. 1035- 1037, August, 1953. 
 14.4), aircraft landing or ground-control approach (GCA) radars, 157 and hostile­ weapon-location radars.' 58  8.11 APPLICATIONS OF THE ARRAY IN RADAR  The phased-array antenna has been of considerable interest to the radar systems engineer  because its properties are different from those of other microwave antennas. The array antenna  takes several forms: ·  Mechanically scanne,I array. The array antenna in this configuration is used to form a fixed  beam that is scanned by mechanical motion of the· entire antenna. 
  3YSTEM .OISE 2ELATIVE    TO !$ .OISED"  -AXIMUM 0OINT #LUTTER    OR 4ARGET ,EVELD"M 
 PUT WHEN THERE IS AN UNBALANCE CAUSED BY THE TARGET BEING OFF AXIS 4HE 2& CIRCUITRY FOR A CONVENTIONAL FOUR 
 Hansen and A. J. Zottl, “The detection performance of the Siebert and Dicke-Fix CFAR  detectors,” IEEE Trans ., vol. 
 Inc .. Englewood CliITs, N.J., 1975.  81. 
 Res ., vol. 108,   no. C3, 8054, 2003. 
 While the general accu - racy of the optics region approximations improves as the scattering obstacle becomes  electrically larger, some of them give reasonably accurate results (within 1 or 2 dB)  for objects as small as a wavelength or so. Geometric Optics.  The theory of geometric optics (GO) is based on the conserva - tion of energy within a slender fictitious tube called a ray. 
 It is convenient to plot the  position of the grating lobes when the beam is phased for broadside and observe the  motion of these lobes as the beam is scanned. Figure 13.10 shows the grating-lobe  locations for both rectangular and triangular spacing. For a rectangular array, the grat - ing lobes are located at  cos c os cos c osα αλ α αλxs ys− = ± − = ±x x y ydp dq   p, q = 0, 1, 2, . 
 OUT AFFECTING THE NOISE LEVEL 4HE NOISE LEVEL CALIBRATION ALGORITHM MUST BE DESIGNED TO TOLERATE EXTERNAL INTERFERENCE AND RETURNS FROM RAINSTORMS OR MOUNTAINS AT EXTREME RANGE !NOTHER CONCERN WITH AMPLIFICATION PRIOR TO 34# IS THAT THE NOISE LEVEL AT THE OUTPUT  OF THE 34# ATTENUATOR VARIES WITH RANGE !T CLOSE RANGE  THE NOISE LEVEL INTO THE !$ CONVERTER MAY FALL BELOW THE QUANTIZATION INTERVAL !LSO  A CONSTANT NOISE LEVEL AS A FUNCTION OF RANGE AT THE RECEIVER OUTPUT IS DESIRABLE IN ORDER TO MAINTAIN A CONSTANT FALSE ALARM RATE .OISE INJECTION AFTER THE 34# ATTENUATOR IS USED TO OVERCOME THIS PROBLEM  ! NOISE SOURCE AND ATTENUATOR ARE OFTEN EMPLOYED AT )& TO INJECT ADDITIONAL NOISE TO  COMPENSATE FOR THE REDUCED NOISE AFTER THE 34# ATTENUATOR $IGITAL CONTROL OF THE NOISE INJECTION IS SYNCHRONIZED WITH THE 34# ATTENUATION TO PROVIDE AN EFFECTIVE CONSTANT NOISE LEVEL AT THE !$ CONVERTER INPUT 'AIN #ONTROL #OMPONENTS  -OST MODERN RADARS PERFORM GAIN CONTROL DIGITALLY  $IGITAL CONTROL PERMITS CALIBRATION OF EACH ATTENUATION VALUE TO DETERMINE THE DIFFER 
 IN POTENTIAL OF THE EMITTER 
 The dot - ted line is the SINR for the quiescent (absence of adaptivity) pattern: it mimics the  reciprocal of the sidelobe and main-beam pattern. The continuous line is the SINR  for the adaptive irregular sub-array architecture; the maximum value of the SINR is  (10log1012 – tapering losses ). Figure 24.12 depicts the SINR for the regular array configuration and absence of  tapering. 
 14, the parts shown asheavy double lines transmit theradio-frequency (r-f) energy from themagnetron tothe antenna, and carry the faint echo signals into the T-branch where the receiving apparatus islocated. For the types ofradar treated inthis book this function isperformed bycoaxial lines and waveguides. A considerable body oftheory and anew setoftechniques have grown up around this class oftransmission circuits. 
 The shape of the . 146 INTRODUCTION TO RADAR SYSTEMS  ~ Transmitter to receiver leakage  Altitude return-...,..  Frequency ,,,, Main-lobe clutter y  ,.-Target echo (head-on)  fo+fc t fo+fd  f0+2v/A  Figure 4.36 Portion of the received signal spectrum in the vicinity of the RF carrier frequency h. 
 The signal isconsidered asseen inatime interval Atifatleast once during this interval itwas distinguishable inthe noise. The interval length is 1L.B.Linford, D,Williams, V.Josephson, W.Woodcock, and supplement by L.B.Linford, RLReport No.64-10, Nov. 12,1942.. 
 a20 (2.39a)  where era, is tile average cross section over all target lluctuations.  Case 2. The probability-density function for the target cross section is also given by Eq. 
 BEAM DIRECTION OF THE ARRAY 7HEN AN INTERFERING SOURCE IS PRESENT IN THE SIDELOBE REGION  THE SUBARRAY 
 In Figure 17a, with increasing wind speed, the value of Δσbecomes smaller, indicating that the eddy spirals become less obvious. Meanwhile, in Figure 17b, the value of Δσrincreases with the increasing wind speed, indicating that the brightness contrast of the entire SAR image increases. In addition, there is a considerable value difference of Δσrbetween different wind speeds, but the value difference of Δσis relatively small. 
 Cohn. M., and A. F. 
 A subsidence proﬁle passing through stations A and B is shown in Figure 10b. The rate of subsidence decreases with the distance to subway stations. Therefore, subway construction can affect land subsidence. 
 A. Oliner and G. H. 
 =   )%%%   (OUSTON    PP n  * . $ENENBERG  2 * 3ERAFIN  AND , # 0EACH  h5NCERTAINTIES IN COHERENT MEASUREMENT OF THE  MEAN FREQUENCY AND VARIANCE OF THE DOPPLER SPECTRUM FROM METEOROLOGICAL ECHOES v IN  TH #ONF  2ADAR -ETEOROL  !-3  "OSTON    PP n  2 * +EELER AND # , &RUSH  h#OHERENT WIDEBAND PROCESSING OF DISTRIBUTED TARGETS v IN  0ROC  )NT  'EOSCI  AND  2EMOTE  3ENSING  3YMP  ;)'!233 
 TO 
 LIMITED DETECTION .EAR SURFACE TARGETS OF INTEREST WILL OFTEN HAVE RADIAL VELOCITIES OF A FEW MILES PER HOUR FOR LONG PERIODS OF TIME  WHICH FORCES THE DETECTION OF GROUND MOVING TARGETS WELL INTO MAIN 
 OUT 
 There is also a related  crossed-field amplifier  (CFA) that has been used in some radars in the past, but it  also suffers limitations for important radar applications, especially for those requir - ing detection of moving targets in clutter. The high-power klystron and the traveling  wave tube (TWT) are examples of what are called linear beam tubes . At the high  powers often employed by radars, both tubes have suitably wide bandwidths as well  as good stability as needed for doppler processing, and both have been popular. 
 FUL 3!2 IMAGING 4HE WORK OF #UTRONA ET AL AND 3HERWIN ET AL  PLUS MANY OTHER  EARLY 3!2 PAPERS  ARE COMPILED IN A VERY USEFUL BOOK BY +OVALY -ORE DETAILED  HISTORIES OF 3!2 DEVELOPMENT ARE GIVEN BY #URLANDER AND -C#ONOU GH  *ACKSON AND  !PEL  AND !USHERMAN ET AL £Ç°ÎÊ /9* 
 VI, 1000 ft; (b) ASV Mk. VII, 1000 ft; solid lines upwind; dashed line downwind.Airborne Maritime Surveillance Radar, Volume 1 7-11. plus-noise can be plotted as a function of range. 
 This reduces thereceiver gain atthe instant ofradar transmission, with theloss ofonly oneortwo microseconds ofvideo-signal reception. 17.13. A100-Mc/sec Frequency-modulated Equipment.—A second type ofequipment which has been used forair-to-ground orair-t~ship. 
 TO 
 STATE 'AIN 2ELATION AND  4RACKING )NDEX 4UNING -ETHOD #HARACTERISTICS -ODEL NO  7HITE NOISE SPECTRAL DENSITY Q G (Z   ACCELERATION SAMPLED BY RADAR MEASUREMENT Q44 44KK KK  B        
 21 Thus the fact that sea clutter is less at the lower frequencies is but one of several  factors to be considered in the selection of the optimum frequency for a particular radar  application.  Polarization. Figure 13.3 indicates that horizontal polarization results in less sea clutter than  vertical, for the sea conditions which apply to that data. 
 16.13  16.5 Scanning-Motion Co mpensation  ............................  16.14  Compensation-Pattern Selection  ........................  16.16  16.6 Simultaneous Platform Motion and Scan  Compensation  ........................................................ 
 On crystals where thesame current ismetered remotely aswell, acut-in jack isused. Another current worth metering istheaverage diode current inthesecond detector, forover-all sensitivity ytests and checking thereceiver. Ajack formeasuring the keep-alive current intheTR tube should beincluded toprovide verification that theTR switch isperforming normally. 
 Inevitable variations in gain and phase aris - ing from small antenna positioning errors, ground screen inhomogeneities, differences  between preamplifiers, mutual coupling, cable mismatch, thermal and other variations  of cable characteristics, and all the analog stages of the receiver result in distortion of  the beam shape (and hence degraded radar resolution), elevated sidelobes (and hence  vulnerability to clutter and interference), pointing errors (and hence increased tracking  errors), and interferer wavefront geometry perturbations (and hence wasted degrees of  freedom in adaptive beamforming). To mitigate these effects, HF radars must employ sophisticated calibration schemes.  Several approaches have been tried: • Use of an external radiating element in the near-field in front of the array. 
 for a change in range corresponding to one RF wavelength. For this reason, the extrac­ tion of the higher-order modulation frequencies is not practical with a stationary target, such  as in an altimeter.  In order to use the properties of the Bessel function to obtain isolation in an FM-CW  altimeter, when the doppler frequency is essentially zero, the role of the doppler frequency shift  may be artificially introduced by translating the reference frequency to some different value. 
 TIVELY EASILY TO A NEW HARDWARE ARCHITECTURE AS PART OF A TECHNOLOGY REFRESH CYCLE /N THE NEGATIVE SIDE  THESE SYSTEMS CAN BE DIFFICULT TO PROGRAM TO SUPPORT REAL 
 Considine, B.: personal communication, Raytheon Company, January 1988. 3. Watkins, E. 
 The digital target extractor provides the radar output in a form suitable for transmission  over narrowband telephone lines rather than require wideband microwave data links. Sliding­ window detectors .determine the range and azimuth centroid of the radar returns using the  m-out-of-n detection criterion. t. 
 anddopplerfrequency sensitivity withouttheaccompanying disadvantage ofhighattenuation asexpericnccd inthesubmillimcter rcgion.Bccausc ofitssmallphysical apcrture alaserradar isnotsuitedformostsurveillance applications. Itis,however, wellsuitedforprecision measure­ mentandtargetimaging..Thedesignofalaserradarfollowsthesamegeneralprinciples as otherradars.hutwithsomecxceptions.RS.93.94.I05 Inaddition tousingatransmitter unlikethosefoundatmicrowave frequencies, thelaser radaI'exlJibitsotherdirlercnces thatIllustbeaccounted forwhenconsidering radardesign.For example. thereceiversensitivity isnotdetcrmined bythermalnoiseasatmicrowaves, butby quantumellccts.Thenoisepowerperunitbandwidth atmostlascrfrequencies isgivcnby No=hI' (14.3R) (14.39)\vhereII=Planck's constant=6.626x10-J-lJ .s,andf=frequcncy. 
 ' 4.5DIGITAL SIGNAL PROCESSING Theintroduction ofpractical andeconomical digitalprocessing toMTIradarallowed a significant increase intheoptionsopentothesignalprocessing designer. Theconvenience of digitalprocessing meansthatIllultiple _~~Iay-line canc~I_~rs_wi\h tailoredJrc'l-l1ency-response characteristics canbereadilyachieved. 1\digitalMTIprocessor doesnot,inprinclpte-;do any hettcrthanawcll-designed analogcanceler; butitismoredependable, itrequires lessadjust­ mentsandattention, andcandosometaskseasier.Mostoftheadvantages ofadigitalMTI processor areduetoitsuseofdigital~Ji~ ratherthananalogdelaylineswhichare characterized byvariations duetotemperature, criticalgains,andpooron-lineavailability. 
 J. Doviak, D. S. 
 WATER DATA IS FROM A FIXED SITE ON A PIER  FROM 7 # +ELLER ET AL   .   3%! #,544%2  £x°ÓÎ IS DUE TO THE SMALL 
 For these range-doppler  cells, when the guard channel return is greater than that of the main channel, the  detection is rejected (blanked). If the main channel return is higher, the detection  is passed on. A block diagram of a guard channel mechanization is shown in Figure 4.10. 
 When birds travel in Ilocks.  the total cross section can be significantly greater than that of a single bird. Because the radar  screen collapses a relatively large volume of space onto a small radar screen, the display can  appear cluttered with bird echoes even though only a few birds can be seen by vistial examina-  tion of the surrounding area. 
 This table gives the decibel attenuation per kilometer in rains of different rates of fall for radio wavelengths between 0.3 and 10 cm. Since the total-attenuation cross section28 depends on the temperature (be- cause of its effects on the dielectric properties of water), it is important to eval- uate the attenuation of rains whose drops are at different temperatures from those in the preceding tables. Table 23.4 contains the necessary data relative to the change of attenuation with temperature and is to be used with Table 23.3. 
 Matcl1tng s,gnal  (a)  (c) EXTRACTION OF INFORMATION A.NU WAVEFORM DESION 425  \  I Figure l l.17 Three basic forms of  SAW interdigital transducers for  linear FM pulse compression. (a)  Dispersive delay line with dispersion  designed into one transducer; (b)  dispersion in both transducers, and  (c) a reOective array compressor  (RAC). (From Maines and Paige,21  courtesy of Proc. 
 SITU VERIFICATION v  *  !TMOS /CEAN 4ECHNOL  VOL   PP n  . 
 Learning Models. ( a) Traditional CNN models. ( b) Resnet-34 models. 
 The road, farmland and other detailed information can be well distinguished in the proposed KA-DBS imaging results. Therefore, the proposed KA-DBS algorithm can improve the cross-range resolution at the situation of short dwell time. 80. 
 The other one is the parametric method [ 9,10]. It assumes that the scene includes some scattering targets and that their scatterings follow some functions. The scattering functions of the targets are ﬁtting with the whole aperture data included. 
 #/5.4%2-%!352%3   Ó{°Ç 4HE $2&- IS THE PRINCIPAL MEANS TO IMPLEMENT A DECEPTION JAMMER THE RANGE 
 ONSTRATED THAT RADAR CAN DETECT THE GAS SEEPAGE THAT IS OFTEN FOUND OVER UNDERGROUND OIL AND GAS DEPOSITS  £°£äÊ  " 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 
 [ CrossRef ] 7. Xu, G.; Yang, J.; Dong, C.; Chen, D.; Wang, J. Statistical study of submesoscale eddies identiﬁed from synthetic aperture radar images in the luzon strait and adjacent seas. 
 JAM RATIOS (OWEVER  THE DATA LINK ON A WEAPON IS TRAVELING TO THE TARGET  WHICH WILL INEVITABLY ATTEMPT TO PROTECT ITSELF 7HEN THE WEAPON IS NEAR THE TARGET  THE SIGNAL 
 Automatic Detection, Tracking, and Sensor  Integration   ............................................................... 8.1  8.1 Introducti on  .............................................................  8.1  8.2 Automatic Detection  ............................................... 
 Z. Peebles, Jr., “Multipath error reduction using multiple target methods,” IEEE Trans .,   vol. AES-7, pp. 
 PLING OF THE RECEIVED SIGNAL AT REGULAR INTERVALS AS INDICATED IN &IGURE  &)'52%   4YPICAL SAMPLING RECEIVER USED FOR TIME 
 Woodward-Levinson method. Another methodofapproximating thedesiredantenna pattern withafiniteaperture distribution consists inreconstructing theantenna patternfromafinite number ofs~.mpled values.Theprinciple isanalogous tothesampling theoremofcircuittheory inwhichatimewaveform oflimitedbandwidth maybereconstructed fromafinitenumberof samples. Theantenna-synthesis technique basedonsampled valueswasintroduced byLevin­ sonattheMITRadiation Laboratory intheearlyfortiesandwasapparently developed independently byWoodward inEngland.7.77-79 Theclassical sampling theorem ofinformation theorystates:Irafunctionf(t) contains no frequencies higherthanWHz,itiscompletely determined bygivingitsordinates ataseriesof pointsspaced1/2Wseconds apart.Theanalogous sampling processappliedtoanantenna pattern isthattheradiation patternEa(¢)fromanantenna withafiniteaperture discom­ pletelydetermined byaseriesofvaluesspacedA/dradiansapart,thatis,bythesamplevalues E,(IJA/d), where IJisaninteger.73InFig.7.23aisshownthepatternE(¢)andthesampled pointsspacedAidradiansapart.Thesampled valuesE,(nA/d), whichdetermine theantenna pattern, areshowninb. 
 . Óx°ÎÓ  2!$!2 (!.$"//+  #AREFUL INSPECTION OF THE DECIMATOR ARCHITECTURE REVEALS A POTENTIAL PROBLEM WITH  THE INTEGRATOR 4HE INPUT SAMPLES CONTINUALLY GET ADDED TO THE RUNNING SUM  PRODUCING A  DEFINITE OVERFLOW CONDITION 4HE BEAUTY OF THE ARCHITECTURE IS THAT OVERFLOWS ARE ALLOWED AND COMPENSATED FOR BY THE COMB SECTION  AS LONG AS THERE ARE ENOUGH BITS IN THE ADDERS TO REPRESENT THE MAXIMUM EXPECTED OUTPUT VALUE AND THE FILTER IS IMPLEMENTED USING TWOS COMPLEMENT ARITHMETIC !S DESCRIBED BY (ARRIS   THE NUMBER OF BITS REQUIRED IN  THE ADDERS B!$$%2  IS GIVEN BY   B!$$%2   B$!4!   #%),;LOG'!). =  WHERE B$!4! IS THE NUMBER OF BITS IN  THE INPUT DATA AND  #%),; = INDICATES ROUNDING THE  NUMBER IN THE BRACKETS TO THE NEXT HIGHEST INTEGER '!). IS GIVEN BY   '!).   2+  WHERE 2 IS THE DECIMATION FACTOR AND +  IS THE NUMBER OF STAGES IN THE FILTER  RESULTING IN  B!$$%2   B$!4!   #%),;LOG2+ =  &OR EXAMPLE  ASSUME WE HAVE  
 A(z), the aperture  distrih11tio11. or ill11111i11atio11, may be written as a complex quantity, including both the ampli­ tude and phase. or  A(z) = I A(z) I exp j'l'(z)  .. 
 D. L.: Limitations or Radar Techniques ror the Detection of Small Surface Targets in  Clutter, The Radio and Electronic Engineer, vol. 45, pp. 
 TION IN GAIN WHEN THE MAIN BEAM IS SCANNED OFF BROADSIDE 4HE PROJECTED AREA OF THE %3! APERTURE DECREASES AS BEAM SCANS FROM BROADSIDE 0ROJECTED AREA DROPS AS COSINE OF SCAN CONE  ANGLE -UTUAL  COUPLING BETWEEN RADIATING ELEMENT S FURTHER REDUCES THE  EFFECTIVE AREA 3CAN LOSS MUST BE ACCOUNTED FOR ON TRANSMIT AND RECEIVE "EAMSHAPE ,OSS  4HIS TARGET 
 Soame and D. M. Gould, “Description of an experimental bistatic radar system,” in IEE  Int. 
 POWER DECAY WITH A DECREASING GRAZING ANGLE &OR THESE (& WAVELENGTHS OF TENS OF METERS  THE SEA IS RELATIVELY FLAT  AND THE SCATTERING LAWS ARE SIMPLE ! DETAILED DISCUSSION OF (& RADAR MAY BE FOUND IN #HAPTER &)'52%   $IFFERENTIAL BEHAVIOR OF VERY LOW 
 Figure 6.22 illustrates a number of feed types, many of which are described in more detail in antenna references.3'36'37 . FIG. 6.22 Various types of feeds for reflector antennas. 
 The left 5˚ and the right 5˚ are painted while the antennais not pointed directly towards the target. The bearing must be read at thecenter of the pip. Figure 1.21 - Angular distortion. 
 a = half angle of the cone 9. Empirical values reported by Knott, Shaeffer, and Tuley14TABLE 14.1  RCS Approximations for Simple Scattering Features ch14.indd   10 12/17/07   2:46:49 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 where (fr is the azimuth beam width, PRF is the radar pulse repetition frequency in hertz, RPM is the azimuthal scan rate in revolutions per minute, and Qe is the target elevation angle. This formula strictly applies only if <j>/cos Qe, the "ef- fective" azimuth beamwidth, is less than 360°. (At values of 6e for which <|>/cos 6e is greater than 360°, the number of pulses computed from this formula will obvi- ously be meaningless. 
 Thereceiver isaconventional superheterodyne exceptforfeatures peculiar totheconical­ scantracking radar.Onefeaturenotfoundinotherradarreceivers isameansofextracting the conical-scan modulation, orerrorsignal.Thisisaccomplished aftertheseconddetector inthe videoportionofthereceiver. Theerrorsignaliscompared withtheelevation andazimuth reference signalsintheangle-error detectors, whicharephase-sensitive detectors.;} 7Aphase­ sensitive detector isanonlinear deviceinwhichtheinputsignal(inthiscasetheangle-error signal)ismixedwiththereference signal.Theinputandreference signalsareofthesame frequency. Theoutputd-cvoltagereverses polarity asthephaseoftheinputsignalchanges through 180°.Themagnitude ofthedocoutputfromtheangle-error detector isproportional to theerror,andthesign(polarity) isanindication ofthedirection oftheerror.Theangle-error­ detector outputs areamplified anddrivetheantenna elevation andazimuth servomotors. 
 3.5. Second Experiment: Datasets Using Resnet-50 Model In the second experiment, we used the Resnet-50 models deal with D1, D2, and D3 datasets. The models was shown in Figure 1b. 
 V !$    ! A  
 The equations that shift the phase of complex number I0 + jQ0 by an angle q  to  produce I1 + jQ1 are as follows:  I1 = I0(cos(q  )) − Q0(sin(q  ))   Q1 = I0(sin(q  )) + Q0(cos(q  ))  These equations can be manipulated to provide  I1 = cos(q  )[I0 − Q0(tan(q  ))]   Q1 = cos(q  )[Q0 + I0(tan(q  ))]  The CORDIC algorithm takes advantage of this relationship to approximate an arbi - trary phase shift by implementing multiple stages of phase shifts, where the tangent of  the phase shift in each successive stage is the next smaller fractional power of 2, and  multiplication by this number can be implemented by shifting the input data bits an  integer number of places. The first few stages are as follows:  I1 = cos(q0)[I0 – Q0(tan(q0))] = cos(q0)[I0 – Q0(1)]   Q1 = cos(q0)[Q0 + I0(tan(q0))] = cos(q0)[Q0 + I0(1)]   I2 = cos(q1)[I1 – Q1(tan(q1))] = cos(q1)[I1 − Q1(½)]  Q2 = cos(q1)[Q1 + I1(tan(q1))] = cos(q1)[Q1 + I1(½)] Table 25.1 shows these parameters for an eight-stage CORDIC processor. Each  row of the table represents successive iterations of the algorithm. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.40  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 range delay coarse and fine values, corrected by the remaining height error measured  from the waveform’s position in the tracker. 
 NIFICANT ACTION FROM A RADAR PERSPECTIVE IS TO PRODUCE SUBSTANTIALLY HIGHER IONIZATION LEVELS THAT PERSIST AT USABLE LEVELS THROUGH THE NIGHT  SO HIGHER RADAR FREQUENCIES CAN BE EMPLOYED AND THE MINIMUM ACHIEVABLE RANGE DECREASES )N ADDITION  THE HEIGHT OF THE MAXIMUM ELECTRON DENSITY INCREASES  SO ONE 
 Conf. Radar–87 , Conf. Pub. 
 This relative freedom from cliffraction effects, together with thehigher antenna gains, gave the 100-Mc/sec equipment better performance intheabsence ofsevere interference than that ofthe 300-Mc/sec system. Under the test conditions, satisfactory results were achieved atranges upto100 miles with the airplane flying at 10,000 ft. However, agreat deal ofinterference exists inthis frequency band inbusy locations. 
 By contrast, Figure 25.2 depicts a typical digital receiver for a radar front end.  The RF input usually passes through one or two stages of analog downconversion to  generate an Intermediate Frequency (IF) signal that is sampled directly by the ADC.   A digital downconverter (DDC) converts the digitized signal samples to complex form  at a lower rate for passing through a digital pulse compressor to backend processing. 
 The sorting and acquisition of radar signals is preliminarily made by an ESM system; afterwards it cues the ARM, which continues homing on the victim radar by means of its own . antenna, receiver, and signal processor. Acquisition depends on the direction of arrival, operating band, carrier frequency, pulse width, PRI, scan rate, and other parameters of the victim radar. 
 vol. 18. No. 
 MODEL TESTING  HOWEVER  ARE DOMINANTLY METALLIC  FOR WHICH THE PERFECTLY CONDUCTING SCALING LAW IS GENERALLY REGARDED AS ADEQUATE 7HEN NORMALIZED WITH RESPECT TO THE SQUARE OF THE WAVELENGTH  THE 2#3 PATTERNS  OF TWO PERFECTLY CONDUCTING OBJECTS OF IDENTICAL SHAPE BUT DIFFERENT SIZE WILL BE IDENTI 
 The linear deformation velocity vwas within the range of [−0.2, 0.1 ]m/y. The real parameter ﬁelds of elastic modulus, viscosity, and linear velocity were simulated by a two-dimensional Gaussian function model. The elevation correction ΔZwas simulated through a Gaussian random simulator, with the value controlled within the range of [−50, 50 ]m. 
 ! REPLICATES EXACTLY THE INPUT SIGNAL UP TO THE POINT WHERE THE TRANSISTOR VOLTAGE AND CURRENT LIMITS ARE REACHED )N PRACTICE  #LASS 
 130. S. T. 
   2!$!2 #2/33 3%#4)/.   £{°Óx USED WHEN THE INCIDENT ELECTRIC FIELD IS PARALLEL TO THE EDGE  4- POLARIZATION  AND THE  SUM WHEN THE INCIDENT MAGNETIC FIELD IS PARALLEL TO THE EDGE 4% POLARIZATION  4HE DIVERGENCE FACTOR ACCOUNTS FOR THE DECAY IN AMPLITUDE AS THE RAYS SPREAD AWAY  FROM THE EDGE ELEMENT AND INCLUDES THE EFFECTS OF THE RADIUS OF THE EDGE IF IT IS CURVED   AS AT THE END OF A TRUNCATED CYLINDER  AND THE RADIUS OF CURVATURE OF THE INCIDENT PHASE FRONT  4HE DIVERGENCE FACTOR FOR A TWO 
 , University  of Michigan, Ann Arbor, 1974, pp. 189–217. 117. 
 LIMITED #ASE  4HE FOREGOING DISCUSSION ASSUMED THAT THE TARGET FELL  IN THE NOISE 
 Geosci. Remote Sens. 2011 ,49, 3703–3712. 
 the antenna. The deleted areas have low illumination and therefore least contri- bution to the gain. However, circular and elliptical outlines produce sidelobes at all angles from the principal planes. 
 Acomparison isshownin Fig.10.5ofthedetection probabilities whenthesignalparameters areknowncompletely (coherent detector) andwhenthesignalisknownexceptforphase(envelope detector).24 The abscissa isplottedas2E/N0insteadofsignal-to-noise ratio.whereEisthesignalenergyand Noisthenoisepowerperhertzofbandwidth. Although thecoherent detector maybeofsuperior sensitivity thanotherdetectors itis seldomusedinradarapplications sincethephaseofthereceived signalisnotusuallyknown. 10.6PERFORMANCE OFTHERADAR OPERATOR .) Therateofinformation inherent inatypicalradarsignalisconsiderably greaterthancanbe handled byahumanoperator. 
 THE 
 155-158, American Meteorological Society, Boston, 1986. 79. Meneghini, R., and D. 
 Gardner: Doppler Spectra of S Band and X Band Signals, IEEE Tru~u. Suppl,  vol. AES-3, no. 
 The effect on a pulse waveform is to  change the phase of the reflected wavelet so that targets with different relative dielec - tric constants to the host material show different phase patterns of the reflected signal.  However, the propagation parameters (relative dielectric constant and loss tangent) of  the host material, the geometric characteristics of the target, and its dielectric param - eters affect the amplitude of the reflected signal. Clutter. 
 IRE, vol. 38, pp. 1197-1203, October, 1950. 
 75 1.47 l.32  Maximum gain reduction (dB) 4.1 2.8 l.9 1.3  Relative total number of elements:  t. Equal gain at max scan · 1.22 1.00 1.05 l.04  2. Equal beamwidth at max scan 1.45 1.00 0.92 0.84  3. 
 FILTER GAIN PLUS INTERFERENCE WITH GAIN REDUCED BY MISMATCH 4HESE SIGNALS ADD VECTORIALLY TO MODIFY THE PATTERN 
   -%4%/2/,/')#!, 2!$!2   £°Ç !TTENUATION %FFECTS  !TTENUATION HAS AT LEAST TWO NEGATIVE EFFECTS ON METEORO 
 FACE  IS GUIDED AROUND THE REAR OF A SMOOTH BODY  AND IS THEN LAUNCHED BACK TO THE RADAR WHEN IT REAPPEARS AT THE SHADOW BOUNDARY ON THE OPPOSITE SIDE !S SHOWN IN THE NEXT SECTION  THE CREEPING WAVE CAUSES THE ECHOES FROM SMALL SPHERES TO VARY WITH SPHERE SIZE 4HE MECHANISM CAN ALSO BE PRESENT FOR OTHER SMOOTH BODIES   SUCH AS THE GENERIC  MISSILE DEPICTED IN &IGURE  4HE CREEPING WAVE MECHANISM IS NEVER A SIGNIFICANT ONE FOR MILITARY AND CIVILIAN TARGETS )NTERACTIONS 2ELATIVELY STRONG ECHOES CAN OCCUR WHEN A PAIR OF TARGET SURFACES ARE  ORIENTED FOR A FAVORABLE BOUNCE FROM ONE SURFACE TO ANOTHER AND THEN BACK TO THE RADAR  AS IN THE INTERACTION BETWEEN THE FUSELAGE AND THE TRAILING EDGE OF THE RIGHT WING SHOWN . £{°{  2!$!2 (!.$"//+  IN &IGURE  3IMILAR INTERACTIONS OCCUR FOR SHIP TARGETS WHEN BULKHEADS  RAILINGS   MASTS  AND OTHER TOPSIDE FEATURES BECOME MIRRORED IN THE MEAN SEA SURFACE .OT ALL OF THESE MECHANISMS ARE REVEALED IN THE CHARACTERISTICS OF THE SELECTION OF  SIMPLE AND COMPLEX TARGETS  AS SHOWN IN THE NEXT SECTION £{°ÓÊ / 
 BAND SIGNALS WOULD GET FOLDED INTO THE DECIMATED BASEBAND SIGNAL 4HE TYPI 
 ING  THE SECOND PULSE RETURNS PHASE CENTER IS ESSENTIALLY UNCHANGED FROM THE QUIESCENT WEIGHTS  AND THE THIRD PULSE RETURNS PHASE CENTER IS RETARDED BY APERTURE WEIGHTING 'IVEN IDEAL ANTENNA PATTERNS  AND AN APERTURE LARGE ENOUGH TO ADJUST THE PHASE CENTERS  ! " #  $  ! " #  $        #  %!  #  %! '   #    ! !  #% #   !# ! '% !    !# !      !   #!   $#  #  ## !   
 Since the range-sweep feedback amplifier is extremely faithful atlittle cost, the burden ofaccuracy inrange falls on the sawtooth generator, forwhich precision parts ofhigh constancy can easily beused. The prir+ipal disadvantages oftherotating-coil method are: (1)itislimited tocontinuous scanning rates of30to60rpm and to sector scanning ofcomparable angular velocity; (2) off-centering is extremely expensive inpower, and cannot beused fordisplacements of more than two orthree tube radii because ofexcessive distortion and defocusing; (3)forcases demanding minimum weight, even attheexpense ofaccuracy, therotating-coil PPI isless suitable than some other types. 13.16. 
  
 One is not getting something for  nothing, for in those cases in which the integration-improvement factor is greater than n, the  signal-to-noise ratio required for n 1 is larger thari for a nonfluctuating target. The signal­ to-noise per pulse will always be less than that of an ideal predetection integrator for reasonable  values of Pd. It should also be noted that the data in Figs. 
 I. Skolnik, Radar Handbook , 1st Ed., New York: McGraw Hill, 1971.  3. 
 ARRAYS  4HE CALCULATION OF ANALOGUE TAPER IS MADE BY RESORTING TO THE NULLING OF FICTITIOUS  WIDE ANGLE JAMMING  WHICH OCCUPIES THE WHOLE ANGULAR SECTOR WHERE SIDELOBES OF SUM AND DIFFERENCE BEAMS HAVE TO BE KEPT LOW )N &ARINA ET AL   IT WAS FOUND THAT THE  ANALOGUE TAPERING IS A COMPROMISE BETWEEN THE 4AYLOR WHICH IS THE BEST TAPER FOR THE SUM BEAM  AND THE "AYLISS WHICH IS THE BEST TAPER FOR THE DIFFERENCE BEAM   THE DEGREE OF COMPROMISE BEING REGULATED BY AMOUNT OF FICTITIOUS *.2 SELECTED FOR THE SUM AND DIFFERENCE BEAMS ! NUMERICAL EXAMPLE  REPORTED IN &ARINA ET AL   FOR A 5,! OF   .    ELEMENTS AND A UNIFORM DISTRIBUTION OF THE FICTITIOUS JAMMER OUT OF THE MAIN BEAMS OF THE SUM AND DIFFERENCE BEAMS  GIVES A 03,2 OF  D" AND  D" FOR THE SUM AND DIFFERENCE BEAMS  RESPECTIVELY  4HE NEXT STEP IS TO DERIVE THE FIXED TAPERS AT A DIGITAL LEVEL FOR SUM AND DIFFERENCE  BEAMS A SUITABLE TECHNIQUE IS DESCRIBED IN .ICKEL   4HE RATIONALE OF THE APPROACH  &)'52%   3CHEME OF A 0!2                  
 41, pp. 73-76, March 1987. 6. 
 19-21, 1969.  55. Locke. 
 The voltage pattern of Eq. (7.16) is positive over the  entire main lobe, but changes sign in passing through the first zero, returning to a positive  value in passing through the second zero, and so on. The odd-numbered sidelobes are  therefore out of phase with the main lobe, and the even-numbered ones are in phase. 
 199–207, 2000. 49. A. 
 1977.  15. Bean. 
 An apparent extension of the multiple beam concept is to employ a sheet electron  beam, which is as thin and as wide and has as much current as can be achieved con - sistent with other constraints. It has been considered for very high-power klystrons  (150 MW peak power and periodic permanent magnetic, or PPM, focusing) designed  for a very large linear accelerator.12 It is claimed that the beam current density and the  focusing magnetic field can be reduced, be made with fewer parts, might be more reli - able, and can have lower acquisition and operating costs. One possible disadvantage  is that sheet-beam klystrons might not be wideband. 
 L. Hartman: Submillinictcr Research: A  Propagation Bibliography, U.S. Arrrty Missile Command, Rerlstot~e Arsenal. 
 MENTS MADE OVER SO WIDE A RANGE OF FREQUENCIES  GRAZING ANGLES  AND WIND SPEEDS AT THE SAME TIME &IGURE  SHOWS THE  TRENDS FOR BOTH VERTICALLY AND HORIZONTALLY POLARIZED  &)'52%   #OMPARISON OF 8 
 CONVERSIONS  INCLUDING THE  FINAL CONVERSION TO BASEBAND  RETAIN THE COHERENT PHASE RELATIONSHIP BETWEEN TRANSMIT 
 TO 
 It is easier to ensure the accomplishment of the  weapon system's mission than to guarantee that operation of a single radar will not be  degraded. This larger and more important goal, that of fulfilling a military mission, is what  should guide the military systems planner and the radar systems designer. This broader  concept, however, is not appropriate for discussion here. 
 1.: Digital MTI Radar Filters, IEEE Trarts. vol. AU-16, pp. 
 PRONGED APPROACH TO BREAK 
 TEM AND ITS ABILITY TO FOLLOW A STRONG  STEADY SIGNAL CLOSELY (OWEVER  A TYPICAL TARGET  CAUSES SCINTILLATION OF THE ECHO SIGNAL  GIVING ERRONEOUS ERROR 
 The phase-and amplitude-comparison principles can be combined in a single radar to  produce two-dimensional angle tracking with only two, rather than four, antenna beams.28  The angle information in one plane (the azimuth) is obtained by two separate antennas placed  side by side as in a phase-comparison monopulse. One of the beams is tilted slightly upward,  while the other is tilted slightly downward, to achieve the squint needed for amplitude­ comparison monopulse in elevation. Therefore the horizontal projection of the antenna pat­ terns is that of a phase-comparison system, while the vertical projection is that of an  amplitude-comparison system. 
 Ultralow aver- . age sidelobe levels, defined as better than -20 dBi, have been achieved with careful design and manufacturing processes. One other way to describe sidelobe levels (not often used but sometimes meaningful) is by the median level', this is the level such that half of the angular space has sidelobe levels above it and the other half has them below that level. 
 TARGET ECHOES  !LTHOUGH THE ACTUAL DISTRIBUTIONS VARY WIDELY   NO BETTER DESCRIPTION CAN BE GIVEN FOR RELATIVELY HOMOGENEOUS TARGETS 7ITH A 2AYLEIGH DISTRIBUTION  THE  RANGE OF FADING IS ABOUT  D"  SO AN INDIVIDUAL PULSE RETURN MAY BE ANYWHERE IN THIS RANGE 7HEN A TARGET IS DOMINATED BY ONE LARGE ECHO SUCH AS A METAL ROOF ORIENTED TO GIVE  A STRONG RETURN   THE DISTRIBUTION IS BETTER DESCRIBED BY THAT FOR A SINE WAVE IN NOISE )F THE LARGE ECHO IS CONSIDERABLY STRONGER THAN THE MEAN OF THE  REMAINING CONTRIBUTORS  TO THE RETURN  THIS APPROACHES A NORMAL DISTRIBUTION ABOUT THE  VALUE FOR THE LARGE ECHO  4HIS SITUATION IS PARTICULARLY COMMON FOR NEAR 
 Schcfel: A Quasi Linear FM/CW Laser Radar, IEEE 1975  lmernational Radar Co11/en!11ce. Apr. 21-23. 
 $OPPLER  %LEMENTAL !NTENNA 34!0  #ONCEPTUALLY  THE SIMPLEST REDUCTION  IN DEGREES OF FREEDOM IS OBTAINED BY REDUCING THE NUMBER OF TEMPORAL DEGREES OF . Î°ÓÈ  2!$!2 (!.$"//+    ! " 
 3URVEY 
 These signals may then be processed like a conventional amplitude- comparison monopulse receiver. The system shown in Figure 9.11 would provide  a relatively good difference-channel taper, having smoothly tapered E-fields on  each antenna. However, a sum-signal excitation with the two antennas provides a  two-humped in-phase E-field  distribution that causes high sidelobes since it looks  like a two-element array. 
 The nose-on radar cross section is small  and decreases as the square of the wavelength. The cross section is small over a relatively large  angular region. A large specular return is obtained when the cone-sphere is viewed at near  perpendicular incidence to the cone surface, i.e., when O = 90 -a, where a= cone half angle. 
 NEOUS DYNAMIC RANGE    D"  AS POSSIBLE -ORE RECENT OPERATIONAL RADARS AND MOST RESEARCH RADARS ATTEMPT TO ACHIEVE THE MOST SENSITIVITY POSSIBLE AND CAN DETECT MINI 
 Schlcher. D. C.: Radar Detection in Log-Normal Clutter, IEEE 1975 lntemationa/ Radar Confere11ce. 
 PENCIL 
 1.3 provides two other useful forms of the  radar equation (not shown here): one that represents the antenna only by its gain and  the other that represents the antenna only by its effective area. The simple form of the radar equation is instructive, but not very useful since it  leaves out many things. The minimum detectable signal, Smin, is limited by receiver  noise and can be expressed as  S k T BF S No n min= ( / )1 (1.4) In this expression, kToB is the so-called thermal noise from an ideal ohmic conduc - tor, where k = Boltzmann’s constant, To is the standard temperature of 290 K, and B =  receiver bandwidth (usually that of the IF stage of the superheterodyne receiver). 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.62  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 FIGURE 2.64  Mean improvement factor restriction versus amount of limiting and clutter  spectral spread for a two-pulse canceler ( after T. M. 
 A radar with a reflector  antenna designed to generate a cluster of many beams has been sometimes called a pirlc~rsllioti  radar.  In one example of a developmental radar that generated multiple beams, a spherical  transmitting antenna was surrounded by three spherical Luneburg-lens receiving antennas,  each covering a one-third sector of space.'0s The transmitting antenna was a spherical phased  array of several thousand elements, with only a fraction of these energized at any one time to  form a directive beam. Each energized array ele'ment was driven from a separate power  amplifier. 
 The VA-812E, which  was also derived from the same family as the VA-812C, has a peak power of 20 MW with an  itlstatltancous 1-dl3 baridwidtll of 25 MHz and a 40 dB gain. Its average power rating is  300 kW at a duty of 0.015 and a 40 ps pulse width.  RADAR TRANSMITfERS 205 (',,.'-....,..;')'" ..,. 
 A symmetrical waveform typically  has a frequency that increases (or decreases) with time during the first half of the  pulse and decreases (or increases) during the last half of the pulse. A nonsymmetrical  waveform is obtained by using one-half of a symmetrical waveform (Figure 8.9 b).  However, the nonsymmetrical waveform retains some of the range-doppler coupling  of the linear-FM waveform. 
  
 The two circular turns are performed at an acceleration of  1.5 g. The transmitted SOJ noise impacts the radar with power g  0 not exceeding eight  times the receiver noise power. Thus, a SOJ will not completely hide a target, and it can  be defeated with a higher energy waveform. 
 The external appearance of the coaxial magnetron, Fig. 6.4, is similar to that of the  conventional magnetron, and the electron and RF operations that take place in the interaction  space are the same for both types of magnetrons. The differences between the two are in the  more effective mode control of the coaxial cavity as compared to that offered by conventional  strapping. 
 Ocean. Tech ., vol. 19, pp. 
 The rcsi~lt is that a single-frcqitc~icy, ~niiltifrrric-  tion radar riliglit not be as efficient as separate radars operating at separate frequencies, cacli  optitiiized to fi~lfill a single, dedicated fiinctioti. It is co~iceivable in sonie circun~stances that  two ri~tl;irs, oric optiti~izcd lor sirrvcill;ir~cc :111d tlic other for track, will perfor111 better, hc less  costly. and take less total space than a single niultifunction radar. 
 POWER PULSE MODULATOR   4HIS IS CALLED  DC OPERATION %VEN THOUGH DC OPERATION AVOIDS A HIGH POWER MODULA 
 Range ambiguities are not as easy to identify as azimuth ambiguities, because  they arise from ranges outside of the nominal swath, hence not otherwise imaged. Range  ambiguities by definition arise from ranges that are different from those for which the  processor is set, so that range-ambiguous point targets tend to be defocused. The principal means of suppressing ambiguities is to confine the main beam of  the antenna so that the potential sources of azimuth or range ambiguities are not illu - minated, or at least are illuminated only very weakly. 
 The frequency of the next pulse cannot generally be predicted from the frequency of the current pulse.65 Frequency diversity refers to the use of several complementary radar transmissions at different frequencies, either from a single radar (e.g., a radar having stacked beams in elevation by employing differ- ent frequencies on each elevation beam) or from several radars. The objective of frequency agility and diversity is to force the jammer to spread its energy over the entire agile bandwidth of the radar; this corresponds to a reduction of the jam- mer density and resulting ECM effectiveness.15 Signals with wide instantaneous bandwidth exhibit considerable variation of the frequency within each transmit- ted pulse. A spread of about 10 percent of the transmitter center frequency can be proper. 
 III. However, by the end of 1943, production of ASV Mk. IIIA had been replaced by ASV Mk. 
 Against a submarine trimmed down the ranges were 7 miles at 1500 ft, 6 miles at 1000 ft and 4 miles at 500 ft. Minimumranges varied from 3 miles to 1 mile. It was thought that an increase of about 20% in range might be achieved when the broadside arrays were used. 
 www.tektronix.com/radar  5  Pulse top amplitude (Power) and Pulse Width (PW) are  important for calculating the total energy in a given pulse  (Power x Time). Knowing the duty cycle and the power of a  given pulse, the average RF power t ransmitted can be  calculated (Pulse Power x Duty Cycle).   Radar Equation   The Radar Equation , as it is commonly known, defines many  of the engineering trade -offs encountered  by radar designers. 
 The  conical surface as a radiating structure for a conformal array is also of interest since ~nlsbilcs  are sometimes of this shape.  The ogive, which is the type of surface found on the nose of some aircraft, bears a  resemblance to the cone. A conformal array arranged on the aircraft nose would allow wide  coverage, provide a good aerodynamic shape, eliminate the distortion of the pattern of a  mechanically scanned antenna caused by the conventional nose-radome, and would permit  larger antenna apertures than the conventional nose-antenna configuration. 
 Pace, Detecting and Classifying Low Probability of Intercept Radar , Norwood, MA: Artech  House, Inc., 2003. 19. D. 
 147-158, January 1983. 7. Skillman, W. 
 cc   `¯P    #OMPARISON OF THIS RESULT WITH THE DEFINITION OF THE AUTOCORRELATION FUNCTION SHOWS  THAT THE MATCHED FILTER RESPONSE CAN BE EXPRESSED AS   YT    8U 
 RANGE &- 
 SCAN TRACK FOR 
 647 649, July, 1975. (See also comment on p. 325 or ref. 
 B. Wuertz, and R. G. 
 BER OF GATE FINGERS IE  TOTAL  GATE PERIPHERY  IS USUALLY AT A PREMIUM &OR HIGH 
 This housing consists ofathin-walled tube ofLaminac and cotton duck. Inaddition toprotecting theantenna, thehousing isused topressurize theantenna. The largest airborne installation made during the war isinaTBM airplane (Fig. 
 AttenuatIon atnee(dB/km)=-).4 -+--).- (D.29) wherer=snowfall rale(rnm/hofmeltedwatercontent). and)=wavelength. em, 10 ;-1.0 ~ C1Jc:o E<10' CDu-c:o = 2 4 5 6 7 Wavelrngll1. 
 Differences in echo strength are caused by differences in radar cross sections, in meteorological conditions, and in range. The effect of range on radar echo strength overshadows the other causes, however. The radar echo power received from a reflective object varies inversely with the fourth power of the range or propagation time of the radar energy. 
 Dybdal, “Radar cross section measurements,” Proc. IEEE , vol. 75, pp. 
 ASIIfE. .I. t?tr.cic  I;IIOI~. 
 Frequency Hopping   Another modulation technique utilizes  several frequen cy hops  within a pulse. If each frequency has a corresponding filter  with the appropriate delay in the receiver, then all segments  can be compressed together in the receiver. If the frequency  hopping sequence remains the same for all pulses, then the  recei ver compression can  even be implemented with a simple  Surface Acoustic Wave  (SAW ) filter. 
 Pulse Compression Radar Examples.  There are many radars under develop - ment or deployed that utilize some of the pulse compression waveforms previously dis - cussed. Advances in digital signal-processing technology have enabled a wider variety  of waveform implementations. 
 38. Friichtenicht, H. W.: Notes on Duct Influences on Line-of-Sight Propagation, IEEE Trans,  vol. 
 If this charge were  allowed to remain, the peak voltage on the network would increase with each cycle and build  up to a high value with the possibility of exceeding the permissible operating voltage of the  thyratron. The mismatch of the pulse-forming network to the nonlinear impedance of the tube  might also cause a spike to appear at the leading edge of the pulse. The despiking circuit helps  minimize this effect. 
 NavalResearch Laboratory. Washington, D.C.,pp.9-14,December, 1956. 4R.Ulahy.F.1'.:RadarResponse toVegctation, IEEETrans.,vol.AP-23,pp.36-45,January, 1975. 
  P2   A  ! DEDICATED OR COOPERATIVE MONOSTATIC RADAR CAN PROVIDE VALUES OF  P 4 DIRECTLY TO THE HITCHHIKER /THERWISE  THE HITCHHIKER MUST ESTIMATE THE VALUE  FOR  EXAMPLE  VIA AN EMITTER LOCATOR MEASURING THE RADARS ANTENNA SCAN RATE WHEN IT IS PRE 
  
 -ODULATION $ISTORTION  #ROSS 
 One isac-w method; theother involves pulse timing. AC-w Method.—In order toallow transmission ofallthescanner data onone r-fsubcarrier, each item ofinformation can use adifferent audio frequency, the subsequent sorting being done bya-ffilters. Figure 17.11. 
 TION DISTANCE  ETC   WHEREAS NATURAL OR HUMAN 
 of IEEE 1985 Int. Radar Conf. , Arlington (V A), USA, May 6–9, 1985, pp. 
 Angle ^ 1 deg.* = Noise . LJOSS (dB) Frequency (MHz) or El. Angle (deg) Noise (dBW) Loss (dB) Frequency (MHz) or El. 
 TUDE VARIATION THAN THE INPUT SIGNAL AMPLITUDE !T  "ECAUSE  THE MULTIPLICATION PROCESS MULTIPLIES UP THE VARIATIONS IN THE SIGNAL PHASE  BY FACTOR  -  INPUT PHASE NOISE AND SPURIOUS PHASE MODULATIONS ARE INCREASED BY   LOG-  D" 3IMILARLY  VARIATIONS IN THE PHASE OF THE SIGNAL AS A FUNCTION OF FRE 
 One disadvantage is that this feed re- quires a very complex microwave circuit. Also, the divided four-horn portions of the feed are each four element arrays which generate large feed sidelobes in the H plane because of the double-peak E field. Another consideration is that the 12- horn feed is not practical for focal-point-fed parabolas or reflectarrays because of its size. 
 Since themain switch iscontrolled byaflip-flop, itwill sooner orlater beopen. Ifnopulse occurs during theopen interval, this switch will close, but itwill beopened again bythenext pulse. Sooner orlater itwill receive apulse when open. 
 BAND NATURAL CLUTTER THUS  IF A PORTION OF A 3!2 IMAGE CORRESPONDS CLOSELY TO A  DIHEDRAL  THEN THE REGION IS LIKELY TO CONTAIN CULTURAL HUMAN 
 L. Mitchell: Detection Probabilities for Log-Normally Distributed Signals,  IEEE Trans., vol. AES-3, pp. 
 (ed.): "TRW Space Data," 3d ed., 1967. 35. Barton, D. 
 Persoon, T. F. Averkamp, F. 
 ¤ ¦¥³ µ´ 
 Nevertheless, matching with octave bandwidth for scanning to ±60° appears possible. Limited Scanning.30 If scanning is limited to a small angular volume, consid- erable simplifications become possible. The total number of active phase-shifter controls can be reduced to about equal the total number of beams. 
 Thediscretefrequency-shift, ortimefrequency coded,waveform isgenerated bydividing a longpulseintoaseriesofcontiguous subpulses andshiftingthecarrierfrequency from subpulse tosubpulse.16.33Thefrequency stepsareseparated bythereciprocal ofthe subpulse width.Alinearstepping ofthefrequency givesanambiguity diagram moreliketheridgeofthe linearFM.Whenthefrequencies areselectedatrandom, theresultisathumbtack ambiguity diagram. Thenumber ofsubpulses Nrequired toachieveathumbtack ambiguity diagram withrandolnfrequency stepping isfarlessthanwiththephase-coded pulse.Toachieveatotal bandwidth B,eachsubpulse needonlyhaveabandwidth BIN.Thewidthofeachsubpulse is thusN/B.Agivenpulse-compression ratioBTcanbeobtained withN=T/{N/B) subpulses, orN=.jBT, insteadoftheBTsubpulses required forthephase-coded pulse.Pulse­ compression ratiosashighas105andbandwidths ofseveralhundred megahertz havebeen obtained.33Withtheproperfrequency-shift sequence, thesidelohe levelonapowerbasisis I/N2downfromthemainresponse.3'"However onthedoppleraxisoftheambiguity function theresulting sidelobes are1/Nratherthan1/N2,whichistheresultofonlyN=.jBT subpulses. According toNathanson,33 thediscretefrequency-shift waveforms arepreferable instead oflinearFMwhenthepulse-compression ratioandthesignalbandwidth arelarge.The resulting thumbtack ambiguity diagram meanstherewillbenorange-doppler coupling to causeerroneous measurements. 
 PASS FILTER CENTERED ON THE )& CARRIER 7HEN A LINEAR 
 11, pp. 847-860, November, 1976.  14INTRODUCTION TORADAR SYSTEMS REFERENCES 1.Guerlac, H.E.:"OSRD LongHistory," vol.V,Division 14,"Radar," available fromOfficeof Technical Services, U.S.Department ofCommerce. 
 Taking the square root of the value of the integral gives  the rms modulation. High-Frequency Amplitude Noise.  High-frequency amplitude noise consists of  both random noise and periodic modulation. 
 20–25, 1980. 46. D. 
 PULSE SIGNAL 
 This whole process was observed byfilter ofice~s who satonabalcony overlooking the map. They were informed ofthe plans forthe move- ments offriendly aircraft. They were able todirect theoperations ofthe whole Chain and todecide which formations should beplotted byeach station. 
 2.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 These velocity response curves are calculated for a scanning radar system with  14.4 hits per one-way 3-dB beamwidth. An antenna beam shape of (sin U)/U, termi - nated at the first nulls, was assumed. The shape of these curves, except very near the  blind speeds, is essentially independent of the number of hits per beamwidth or the  assumed beam shape. 
 DAY REVISIT BASELINES TO SUPPORT INTERFEROMETRY .OMINAL INSTRUMENT MASS IS  KG 0!,3!2  !LTHOUGH BASED ON * 
 A Manual of Applied Mechanics , 3rd ed.; Charles Grifﬁn and Company: London, UK, 1872. 328. Sensors 2019 ,19, 1529 18. 
 The radar displays are seen to form a prominent part of  the system. Radars fitted on smaller fishing vessels and leisure craft share many of the  features of radars designed for ships but are necessarily more compact; a typical small  boat radar is shown in Figure 22.2. Specific requirements for these radars, where they  differ to any extent from the design of shipborne radars, are discussed within relevant  parts of the chapter. 
 BEAM CLUTTER AND GROUND MOVING TARGET FILTER REJECTION NOTCH 4ARGET DETEC 
 For this reason, in most system applica - tions, it is cost-effective to reduce the data sample rate to a value that is just adequate to  support the bandwidth of the system. In applications where the sample rate of a signal is  to be decreased (decimated), the frequency content of the signal must first be reduced so  that the Nyquist criterion is satisfied for the new sample rate. This can be accomplished  by first passing the signal through a digital FIR filter to restrict the bandwidth of the  signal to less than half of the decimated sample rate, and then reducing the sample rate  of the filtered signal by a factor of R by selecting every Rth sample, as described in the  previous discussion of decimation. 
 It expresses the (a posteriori) probability that the signal is present, given  that the receiver input is y.  For a particular input y, the receiver can assess from Eq. (10.23) the probability that a  particular signal was received. 
 SEC. 17.15] AGROUND-TO-GROUND RELAY SYSTEM 727 used toprovide thetwo channels, since, atthetime ofdesign, equipment accommodating subcarriers was notavailable and weight and power were not crucial items. The remaining data arecombined onthese same two channels asindicated inFig. 
 Thefilterhastoberetuned ifthemixermustoperateatanother frequency. Also,thehighQofthefilterintroduces alosswhichwillincrease thesystem noise-figure. /\.methodforachieving areactivetermination withoutnarrow-bandwidth components is theimage-recovery mixershowninFig.9.3.Thishasalsobeencalledanimage-enhanced mixer,I7 orproduct returnmixer.56(Itissimilartotheimage-reject mixer6,7,ll,55whose purpose istorejecttheimageresponse.) TheRFhybriqjunction ontheleftofthecircuit produces a900phasedilTerence between theLainputstothetwomixers.TheIFhybrid junction ontherightimpartsanother 900phasedifferential insuchamannerthattheimages cancel,buttheIFsignalsfromthetwomixersaddinphase.ThetwomixersinFig.9.3maybe single-ended, balanced, ordouble-balanced mixers. 
 Covered and Omitted Topics.  This chapter introduces space-based remote  sensing radars. The focus is on Type II SBRs, as outlined in the previous edition of  this Handbook , including both Earth-orbiting and planetary systems. 
 TION AND INSTALLED IN EXISTING RADARS )T DID THE JOB IT WAS SUPPOSED TO DO  BUT IT IS NOT OBVIOUS THAT THE SOLID 
 1-20, San Francisco, 1979. 45. Fleming, F. 
 NOISE TO MEAN 
 21, pp. 30-34, Dec., 1978,  and vol. 22, pp. 
  D" 4HE COMPOSITE RESPONSE FOR PULSE 
 1, "Data Users Handbook," General Electric Company, Utica, N.Y., May 1976. 9. Soviet Radar Records Venus Surface Imager, Aviat. 
 TheSchottky-barrier diodeshavehadlowernoisefiguresandlower flickernoisethanconventional point-contact diodes,butthesiliconpoint-contact diodehas hadbetterburnout properties. Anintegral partofthemixeristhelocaloscillator. TheIF amplifier isalsoofimportance inmixerdesignbecause ofitsinfluence ontheoverall noise-figure. 
 The absolute value of group delay does not impact the range sidelobe perfor - mance; however, the relative group delay between channels must be tightly controlled  or compensated in monopulse, sidelobe canceler, and digital beamforming systems. Although stopband rejection is clearly a key parameter, filters with fast roll-off  may not provide the required phase and impulse response characteristics. Figure 6.9  shows the magnitude response of six different fifth order low-pass filters with equal  3 dB bandwidth.8 The Chebshev filters (0.1 and 0.01 dB ripple) have flat passband  response and improved stopband rejection relative to the remaining filters; however,  as shown in Figure 6.10 and Figure 6.11, they have inferior phase (group delay) and  impulse response characteristics. 
 93.Cooke,C.R.:LaserRadarSystems, SomeExamples. Proc.Soc.Photo-Opticallnslrumelllation Engi­ neers.vol.128."ElTective Utilization ofOpticsinRadarSystems," pp.103-107, 1977. 94.Fitzmaurice, M.W:NASi\Ground-Based andSpace-Based LaserRanging Systems. 
 The clutter models contained in this chapter are approximations of the types of  clutter that must be addressed. The exact quantitative data, such as precise spectrum  and amplitude of each type of clutter, or the exact number of birds or point reflectors  (e.g., water towers or oil-well derricks) per unit area, is not important, because the MTI  radar designer must create a robust system that will function well no matter the actual  deviation from the clutter models of real clutter encountered. MTI radars may use rotating antennas or fixed apertures with electronic beam scan - ning (phased arrays). 
 SURES OF MERIT FOR ULTRA 
  3PIRIT STEALTH BOMBER USES TRIANGULAR PATCHES . 
 The voltage gain between the grid ofthe first tube and the plate ofthesixth isabout 30,000. The seventh tube isaplate detector, which gives 10-db gain aswell asasomewhat larger power output than could have been obtained from a diode detector ofthe same bandwidth. This advantage, ho,.vever, is ~..--. 
 A detailed analysis of this kind of errors is in Berger.27 ch24.indd   6 12/19/07   6:00:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 Ray, P .S.; Wood, K.S.; Phlips, B.F. Spacecraft navigation using X-ray pulsars. J. 
 Skolnik ed., McGraw- Hill, NY: 1990.   [9] Price, R., "Chebyshev low pulse compression side lobes via a nonlinear FM", National Radio Science Meeting of URSI  (Digest Abstract), Jun 18, 1979, S eattle,  WA.  [10] Johnston, J. 
 POWER MODULATOR  CALLED A CATHODE PULSER MIGHT HAVE TO BE USED TO SWITCH THE TUBE ON AND OFF #ATHODE  PULSERS MUST SWITCH THE FULL BEAM VOLTAGE AND CURRENT SIMULTANEOUSLY  WHICH INVOLVES HIGH INSTANTANEOUS POWERS 4HEY MUST CONTROL THE FULL BEAM POWER OF THE 2& TUBE  EITHER DIRECTLY OR THROUGH A COUPLING CIRCUIT 4HE ENERGY STORAGE DEVICE MIGHT BE MADE UP OF CAPACITORS  INDUCTORS  OR SOME COMBINATION OF THE TWO AS IN PULSE 
 SWITCH MODULATOR MUST OFTEN STORE FAR MORE THAN  * TO PREVENT EXCES 
 The transformations can range  from simple column beamforming to overlapped subarrays to beam-space transfor - mations such as a Butler matrix. The general goal is to reduce the spatial degrees of  freedom, while still providing access to array responses that allow for adequate clutter  cancellation and beams that can be used to cancel directional interference as well. The  resulting beam responses must span the clutter and jamming interference spatially in  order for this type of transformation to be effective. 
 VIEWING FACE OF THE SATELLITE .   30!#% 
 When the radar is on a moving platform or when the clutter is moving rain or sea, the frequency of the coho is sometimes varied to try to compensate for this motion, shifting the clutter spectrum back to zero doppler. The servo which ac- complishes this task, if properly designed, will introduce insignificant instability under ideal environmental conditions (solely clutter echoes and receiver noise typical of laboratory tests), but the effect of strong moving targets and pulsed in- terference from other radars can sometimes be serious, shifting the coho fre- quency from the proper compensation value. Timing signals for the transmitter and A/D converter are usually generated from the coho, and timing jitter can cause clutter attenuation to be degraded. 
 Fig-CODE GENERRTORTO RF HODULRTOR RNO TRRNSMITTER XdetCORRELRTOR SQURRER IN-PHRSE CHRNNEL QURDRRTURE CHRNNELRECEIVED SIGNRLS RT IFSUBPULSE FILTER Qd.tCORRELRTOR SQURRER Phase of transmitted binary element with respect to LOTypical phase of received binary element with respect to LO . ure 10.130 shows a fixed reference correlator; i.e., only one binary sequence is used. The received input sequence is continuously clocked into a shift register whose number of stages is equal to the number of elements in the sequence. 
 lob is a two-pole filter with a multiple pole. It is about 0.3 dB less efficient than the  ideal integrator with optimum weights.66 The double delay-tine configuration of Fig. 10.10~ is  also a two-pole filter but unlike the double-loop integrator, the two poles need not be at the  same location. 
  RADAR FOR A TARGET  ELEVATION REFERENCE. 
 Therefore the antenna beams are not offset, but are  directed to illuminate a common volume in space. Separate antennas are needed since it is  166INTRODUCTION TORADAR SYSTEMS targetmakesanangle0totheperpendicular bisector ofthelinejoiningthetwoantennas. The distance fromantenna 1tothetargetis R Rd.)I=+Sill(2 andthedistance fromantenna 2tothetargetis R2=R-~sin(1 Thephasedifference between theechosignalsinthetwoantennas isapproximately t:..¢=2,l,.7rdsin()..(5.1) Forsmallangleswheresin0~0,thephasedifference isalinearfunction oftheangularerror andmaybeusedtoposition theantenna viaaservo-control loop. 
 2.29, is again the starting point. As shown by Capon,20 the weights of the opti - mum MTI filter are found as the eigenvector corresponding to the smallest eigenvalue  of the clutter covariance matrix and the MTI improvement factor is equal to the inverse  of the smallest eigenvalue. The optimum improvement factor for the three models for  the spectrum of land clutter introduced in Section 2.4 have been computed based on this  above approach. 
 49. Baynton, H. W., R. 
 204  tube, 191  Electromeclianical phase shifters, 297-298  Electron-bombarded semiconductor (EBS)  device. 217 218  Electron gun. 201  Electronic counter-countermeasures. 
 148 HOW RADAR WORKS  A radar navigator working on Gee reception has thus  to follow ‘blue 20’ curve with his pencil until he meets  ‘red 16,’ when he can fix with great precision the position  of his receiver at the intersection of the two isochrone  curves, on both of which he 1s at that moment situated.  In practice he takes his reading, notes the exact time on  his stop-watch, and then does the ‘final fiddling’ after-  wards, logging the exact time of the reading.  There is no co-operation, you will see, between the  Gee network of transmitters and the receiver. 
 4.1 move insingle file. Itmust beconcluded that the restriction which thus arises can beovercome only bytheuse ofmultiple channels. The simplest—at least inconception—and the most direct way todothis is touse two ormore radar systems, apportioning toeach apart ofthe region tobecovered. 
 1997 ,144, 284–292. [ CrossRef ] 23. Li, X.; Liu, G.; Ni, J. 
 As can be noted by observing Figure 16d that the refocused result with the proposed method has some improvement in focusing compared with the original images, DCT and PGA results. The results of ship06 are illustrated in Figure 17. The images with ISAR processing all have certain improvement in focusing compared to the original image. 
 Other significant contributors of uncommon noise  are the noise on the exciter waveform before upconversion, along with amplifiers in  the receiver and exciter signal paths. The undesired SSB phase noise after downconversion by the STALO is the sum of  the uncommon phase noise and the common phase noise reduced by the range factor.  FIGURE 6.4  Effect of range delay on clutter cancellation ch06.indd   16 12/17/07   2:03:12 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Atthereduced pressures ofhigh altitude, clearances required toprevent arc-over from high-voltage points arelikely tobecome exces- sive. Further, the low temperatures ofhigh altitude arelikely tocause condensation, inther-fline, ofthewater vapor that ispresent inwarm sea-level air. The simplest solution forthese difficulties istoseal the transmitter and the r-fline pressure-tight sothat they can bemain- tained atsea-level pressure atany altitude. 
 DELAY ELLIPTIC FILTER USED IN 4$72                 
 By applying Eqs. (9.3) and (9.4) to the simple case of one auxiliary antenna and one jammer, the following results are easily found: E{VMVA*} A 1W = ^ M A] ^p JCR = ±— (9.5) E{\VA\2} 1-|PP It is noted that the optimum weight is related to the correlation coefficient p be- tween the main signal VM and the auxiliary signal K4; high values of the corre- lation coefficient provide high values of JCR. The problem of implementing the optimum-weight set [Eq. 
 1 to 8.2 comparison of various waveforms, 8.27 digital, 25.19 and ECCM, 24.34 to 24.35 ex amples of, 8.30 to 8.36 factors affecting choice of, 8.26 to 8.27.     I_12 Pulse compression ( cont. ) implementation of, 8.28 to 8.30 linear FM, 8. 
   30!#% 
 SHIPS DERIVED BY INVESTIGATORS AT VARIOUS LOCATIONS THROUGHOUT THE WORLD  FOR VARIOUS WEATHER CONDITIONS  AND IN ALL SEASONS OF THE YEAR 4HE FACT THAT NO UNIVERSAL EXPRESSION CAN BE APPLIED TO ALL WEATHER SITUATIONS IS NOT SURPRISING WHEN ONE NOTES THAT RAINFALL DROP 
 This unsym- metrical type oftuning distorts the electric field patterns within the magnetron and therefore limits itseffective tuning range toabout 6per cent. Advantages ofthe method are itsmechanical simplicity and its ability tohandle very high pulse powers. Figure 10.24 shows output power asafunction oftuning adjustment. 
 Consequently, a five-horn  feed has been used as illustrated in Figure 9.8. The five-horn feed is selected because of the simplicity of the comparator that  requires only two magic (or hybrid) T’s for each polarization. The sum and differ - ence signals are provided for the two linear-polarization components and, in an  AN/FPQ-6 radar, are combined in a waveguide switch for selecting polarization. 
 BAND OPERATION IS POSSIBLE. £Î°{ä  2!$!2 (!.$"//+  4HE EXPLANATION GIVEN ABOVE APPLIES TO AN ANTENNA OPERATING AT  A SINGLE #7  FRE 
 A broad range of radar types (bi-dimensional, multi-beam three- dimensional, phased-array), composite clutter, ECM and propagation scenarios, and  a target’s kinematics and RCS features are covered. Input and output data can be  saved, loaded, and exported to other similar applications or for general use (i.e., MS  Office tools for data analysis). A second purpose is to provide a handy and reliable  tool for technicians and engineers performing system setup at the site or acceptance  tests by means of field trials, by providing not only the software tools and models but  also, where required, a database of prediction results, and allowing simple parametric  excursions thereof, without the need to consult a bulky reference documentation. 
 A target is declared present if  L x xp x x H p x x HTnn n( , , )( , , | ) ( , , | )11 1 1 0…… …= ≥  (7.1) where p(x1,…, xn|H1) and p(x1,…, xn|H0) are the joint probability density functions of  the n observations xi under the conditions of target presence and target absence, respec - tively. For a linear envelope detector, the samples have a Rayleigh density under H0  and a Ricean density under H1, and the likelihood ratio detector reduces to  in i iIA xT =∏  ≥ 10 2σ (7.2) where I0 is the modified Bessel function of zero order, s2 is the noise power, and Ai is  the target amplitude of the ith pulse and is proportional to the antenna power pattern.  For small signals ( Ai <<s), the detector reduces to the square-law detector  A x Ti i in 2 2 1=∑ ≥  (7.3) ch07.indd   2 12/17/07   2:12:50 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 pp. 100-105. 340 l0<TIWDUCTION TO RADAR SYSTEMS  72. 
 Sletten: Phase Signature Radars, IEEE Trans., vol. AP-22,  pp. 774-780, November, 1974. 
 A technique, particularly suitable for low-PRF (Pulse Repetition Frequency)  radar, avoids the influence of close-in clutter returns on adaptive weights by simply  selecting for adaptation the clutter-free ranges at the end of each PRI. This tech - nique does not apply to radars operating in high-PRF range-ambiguous modes with  significant clutter in all range cells. If the clutter and jammer cannot be separated,  either in range or doppler domains, then a two-dimensional (in doppler frequency  and angle) adaptive filter might be required; this is particularly true when the statis - tical features of clutter and jammer are not known a priori. 
 The power requirecl depends ontheusual things, including thebancl- width, which inthis case isthe bandwidth ofone element ofthe fre- quency meter—frhich should beabout j.. This scheme, although ithasnotbeen highly developed, Trill undoubt- edly work much asdescribe(l. High range accuracy and small band- widths are possible-in fact one may ha~-e both aton~-e. 
 105. "Radar -Present and Future," London, Oct. 23-25. 
 HAND SIDE TO  MM RIGHT 
 The limiter is a cjrcuit or combination of like circuits whose output is constant over a wide range of input signal amplitudes. The output waveform from a bandpass limiter is sinusoidal, whereas the output waveform from a broadband limiter approaches a square wave. There are three basic characteristics of limiters whose relative importance de- pends upon the application. 
 133, pt. F, pp. 649-657, December 1986. 
 When tlie scattering is not Rayleigh, a quantity similar to Z is defined, which is called the  uqitii~r~lrtrt radar refiectir'ity ,factor 2,. given by70*73  wlicrc rl is tile actual radar reflectivity, or backscatter cross section per unit volume, and I K IZ  is taken as 0.93.  Instead of the rainfall rate r. 
 STATE SYSTEMS DESCRIBED BELOW &ERRITE PHASE SHIFTERS ARE MORE TEMPERATURE 
 -Ê," ÊÊ / 
 Luo, X.G.; Wang, J.J.; Xu, Z.Y.; Zhu, S.; Meng, L.S.; Liu, J.K.; Cui, Y. Dynamic analysis of urban groundsubsidence in Beijing based on the permanent scattering insar technology. J. 
 26.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 The Propagation Factor,   Fp, in the Radar Equation Wayne L. Patterson Space and Naval Warfare Systems Center   Atmospheric Propagation Branch 26.1 INTRODUCTION Paralleling the development of radar technology is the development of the radar equa - tion. 
  
 M.: Ballistic-Missile Defense Radars, IEEE Speclrrtm, vol. 7, pp. 32-41, March, 1970. 
 INDUCED CRASH PER FLIGHT BELOW  n IN THE  PRESENCE OF JAMMING OR COMPONENT FAILURES )N ADDITION  THERE ARE INITIATED BUILT 
 The dopplcr frcquoncy scale tias hccn  normalized so that ttte dominant components are iit + I. AKW = approach resonant wave; KHW =  recede resonant wavu. calibration signal is at left of figure. 
 H. Abrams, B. Levush, A. 
 Appl. MeteoroL, vol. 16, pp. 
 Three general classes of radome are of interest for reflector antenna applica - tions: feed covers , which often have to endure pressure, high voltage, and heating;  covers attached to the reflector , which alter the pattern in a fixed manner; and  external radomes , within which the antenna moves. External radomes are the most  common and will, therefore, be emphasized. Within each class, a variety of skin  and skin-supporting designs is available to minimize the electrical effects under  the constraints of the environment. 
 IEEE, vol. 56.  pp. 
 GERING COMBINED WITH CLUTTER SPECTRAL SPREAD FROM SCANNING AND INTERNAL 
 The unipolar video output is then  ready to be displayed. The digital MTI processor depicted in Fig. 4.21 is that of a single-delay-  line canceler. 
 " $ "!(#  ' # 
 NATIONAL AGREEMENT  SUCH THAT THEY WERE CONSIDERED TO BE REPRES ENTATIVE OF CONDITIONS  AROUND THE WORLD AGREED 
 The proposed approach, at the state of the art, works well in the presence of a strong point scatterer in the scene. The main idea is to exploit all the inherent information intrinsically stored in the data itself to extract the focusing reference functions to be used in a Ω-K or RD algorithm to obtain the Single Look Complex of any SAR sensor without even knowing important ancillary data parameters, needed by all the SAR focusing processors, such as the distance at the center of the beam, the radar sampling frequency, the transmitted chirp bandwidth, the chirp rate, and the chirp duration, the radar wavelength, the PRF, the sensor speed and the off nadir angle, used in data acquisition. The proposed approach has been tested on several images of ERS raw data, made accessible for the scientiﬁc purpose from the Italian Space Agency (ASI) and the cross comparison with the state of the art focusing algorithm were carried out. 
 R. E. Watson, “Receiver dynamic range: Part 1,” Watkins Johnson Company, Technical Note,  vol. 
 101.Hajovsky, R.G..A.P.Deam.andA.H.LaGrone: RadarReflections fromInsectsintheLower Atmosphere, !EEETrailS..vol.AP-14.pp.224-227. March. 1966. 
 76.Dyer.F.B..M.J.Gary.andG.W.Ewell:RadarSeaClutterat9.5.16.5.35.and95GHz,/974IEEE Alltcnnas andPropagation SocietySymposium. June10-12.1974.pp.319-322. IEEECat.no.74 CH0851-1A P. 
 Another approach to multiple-beam antennas utilized a planar lens array fed by a con­ strained lens consisting of two connected hemispherical surfaces and a hemispherical feed  surface.82 The details of this antenna will not be described here. Its advantage is that it has true  time delay, allowing a wide instantaneous bandwidth.  The Mubis106 antenna, which uses a parallel-plate lens, and the Bootlace107 antenna,  which is a form of lens array, are also capable of RF beam forming. 
   #)6), -!2).% 2!$!2   ÓÓ°ÓÎ -OST SMALL CRAFT RADARS NOW BEING SOLD INCLUDE THE OPTION OF A CHART UNDERLAY FACILITY  AS A RELATIVELY LOW 
 Fedarko4.1 4.1  Characteristics and Applications / 4.1 4.2  Pulse Doppler Clutter / 4.14 4.3  Dynamic-range and Stab ility Requirements / 4.24 4.4  Range and Doppler Ambiguity Resoluton / 4.31 4.5  Mode and Waveform Design / 4.35 4.6  Range Performance / 4.39   List of Abbreviations / 4.48 Chapter 5 Multifunctional Radar Systems for Fighter Aircraft David Lynch, Jr. and Carlo Kopp5.1 5.1  Introduction / 5.1 5.2  Typical Missions and Modes / 5.10 5.3  A-A Mode Descriptions & Waveforms / 5.16 5.4  A-S Mode Descriptions & Waveforms / 5.28 Chapter 6 Radar Receivers Michael E. Yeomans6.1 6.1  The Configuration of a Radar Receiver / 6.1 6.2  Noise and Dynamic-range Considerations / 6.4 6.3  Bandwidth Considerations / 6.9 6.4  Receiver Front End / 6.10 6.5  Local Osc illators / 6.14 6.6  Gain Control / 6.22 6.7  Filtering / 6.24. 
 Nishino, M. Ono, H. Mizutamari, K. 
 70–80, 1999. 33. D. 
 The result in the spectral domain is spurious  modulation sidebands. Random multiplicative noise broadens the spectrum of the car - rier frequency. Discrete multiplicative noise sources generate discrete spectral lines  that can cause false alarms. 
 }}gSDW RD    %RD RW %RD 2 WR [ g} ] [ ] } 
 G. Zornig et al., “Bistatic surface scattering strength at short wavelengths,” Yale University,  Dept. Eng. 
 PASS )N3!2 L .O SPECIAL HARDWARE IS REQUIRED A CONVENTIONAL 3!2 MAY BE FLOWN TWICE OVER THE  DESIGNATED TERRAIN L -OTION COMPENSATION IS CHALLENGING THE POSITION OF THE ANTENNA VERSUS TIME IN EACH  PASS MUST BE KNOWN WITH GREAT PRECISION L ! LONG BASELINE VERTICAL DISTANCE BETWEEN ANTENNA PATHS  PROVIDES FINE VERTICAL  RESOLUTION BUT CHALLENGING AMBIGUITIES  L 4HE SCENE MAY CHANGE BETWEEN PASSES DUE TO WIND  ETC L %XAMPLE RESULTS ARE GIVEN BY 3CHULER ET AL  WHO PERFORM hTERRAIN TOPOGRAPHY  MEASUREMENT USING MULTIPASS POLARIMETRIC 3!2v 3INGLE 
 V-beam radar, is a satisfactory method for obtaining three-  coordinate target information if the number of targets is not excessive. The larger the number  of targets, the more difficult is the problem of correlating the echoes from each of the two  beams. The closer the beams, the easier it is to correlate the echoes, but the iess the accuracy. 
 IEE  (London ), vol. 93, pt. 3A, pp. 
 Therearethreecautions toremember, however, whenconsidering theuseofEq.(13.8).First,theclutterechopowermustbelarge compared tothereceiver noisepowerforEq.(13.8)tobevalid.Thustheenergywithinthe pulsemustnotbetoolow.Ifthepeakpowerislimited,ashortpulsemightnothaveenough energytomakeclutter,ratherthanreceiver noise,dominate. Pulsecompression (Sec.11.5)can overcome thislimitation ofashortpulsesinceitcanachievearesolution equivalent tothatof ashortpUlse.butwiththeenergyofalongpulse.Second,therequired signal-to-clutter ratio depends onthepulsewidthbecause ofthechangeinclutterstatistics (probability density. 484 [NTRODUCTION TO RADAR SYSTEMS  function) with short pulse widths, as discussed in Sec. 
 53. M. A. 
 J. Lewis, Manual of Remote Sensing, Principles and Applications of  Imaging Radar , V ol. 2, 3rd Ed., New York: John Wiley & Sons, 1998. 
 Callada, pp.359-376, 1969. 98.Flock,W.L..andJ.L.Green:TheDetection andIdentification ofBirdsinFlight.UsingCoherent andNoncoherent Radars,Proc.IEEE.vol.62,pp.745-753. June.1974. 
 COUNTERMEASURES ENVIRONMENTS -IRROR 
 1 EEE,  vol. 55, pp. 2 143-2 159, December, 1967. 
 CORRELATED PIXEL BY PIXEL 4HE FAST 
 Ê " *, 
 Artificial signals were injected attbelocations marked, withthefollowing strength, relative toaverage noise power: S1,+10db;S!,+5db; .’%,Odb;S,,–5db. must include more than one scan inestimating theamount oftheintegra- tion, and thescreen persistence again enters. Let ustry toelucidate this rather complicated state ofaffairs by. 
 (12.5). Since the sine varies in magnitude from 0 to 1, the factor q4 varies from  0 to 16. The received signal strength also varies from 0 to 16; hence the fourth-power relation  between range and echo signal results in a variation of radar range from 0 to 2 limes the range  of the same radar in free space. 
 603, chap. 1, Hydrographic Office, U.S. Navy, 1960. 
 l of" Modern Radar," R. S. Berko­ witz (ed.~ John Wiley and Sons, New York, 1965. 
 19.11, the received power can be expressed in terms of the  reflectivity factor Z and range r as  PPG c K Z rrt=2 3 2 2 2512 2 2θφτπ λ| | ( ln ) (19.12) Because the receiving filter suppresses some of the received signal power, Pr must  be reduced by Lr, which depends on the details of the transmitted spectrum and the  receiver filter but is usually a factor of about 1.6 (2 dB) for a typical waveform and  “matched filter.” Solving for the radar reflectivity factor Z gives  Z = [1024 ln2 l2 Lr/Pt G2 q f c t p  3 |K|2] Pr r2  (19.13) where the reflectivity factor is expressed in terms of the received power and range. One must be careful to use consistent units in Eq. 19.13. 
 TEM  THEN THE CIRCULATOR COULD BE REPLACED BY DIODE SWITCHES REQUIRING ADDITIONAL LOGIC AND DRIVING CIRCUITRY £Î°££Ê  1 /* 
 Taking into account the advantages of processing in SAR image, the processing data are SAR image rather than raw echo data in this paper. The ISAR processing is based on fast minimum entropy phase compensation method, an iterative approach to obtain the phase error. The proposed method has been tested using Spaceborne TerraSAR-X, Gaofeng-3 images and airborne SAR images of maritime targets. 
 8, is an antenna with unique  properties that has been of particular interest for radar application.  In this chapter, the radar antenna will be considered either as a transmitting or a receiving  device, depending on which is more convenient for the particular discussion. Results obtained  for one may be readily applied to the other because of the reciprocity theorem of antenna  theory.1 . 
 Since thedescription oftheprocess interms ofrays, traced bythe rules ofgeometrical optics, nowhere involves the wavekngth ofthe radiation, weshould beled toexpect similar effects atallfrequencies forwhich theindex ofrefraction has the same value, namely forallradio frequencies. But, actually, ducts such aswehave described have noobservable eflectonthepropagation oflow- frequency radio waves. The reason forthis isthat theduct iseffective in“trapping” and guiding radiation only ifthewavelength isless than some critical value determined bytheheight ofthe duct and the steep- ness ofthe gradient ofrefractive index within the duct. 
 !       !  &)'52%   3IDELOBE LEVELS  WITH AND WITHOUT BLOCKAGE  VS FEED PATTERN   EDGE TAPER. 
  IS THE CHINE THAT RUNS FROM THE NOSE TO THE ROOT OF THE DELTA WING )N THE NOSE 
 Quite often Swerling case 1 is specified for describing radar performance since it  results in conservative values. The uncertainty regarding fluctuating target models makes the  use of the constant (nonfluctuating) cross section in the radar equation an attractive alterna­ tive when a priori information about the target is minimal.  2.9 TRANSMITfER POWER  The power P1 in the radar equation (2.1) is called by the radar engineer the peak power. 
 Amplitude weighting of the  received signal reduced the higl~est sidelobe to -24 dB instead of - 13.2 dB without weight-  ing. (The compressed pulse was widened because of the weighting.) The filter package  measured 0.5 by 1.5 by 2.25 in. The maximum insertion loss was 40 dB. 
 NAL PULSE TO hLONG TIME  SMALL BANDWIDTHv SIGNALS 3INCE THE SA ME 4"0 IS MAINTAINED   THE ORIGINAL RESOLUTION IS PRESERVED 4HE METHOD IS IDEAL FOR ALTIMETRY  SINCE THE RANGE DEPTH OF THE OCEANS SURFACE IS VERY MUCH SMALLER THAN THE TIME AVAILABLE IN THE PULSE REPETITION PERIOD #LEARLY  THE FULL DERAMP TECHNIQUE OFFERS A CONSIDERABLE SAVINGS IN SYSTEM BANDWIDTH AT ALL SUBSEQUENT STAGES AND AT NO COST IN RAN GE RESOLUTION 4HE FIG 
 Single apertures are also employed by use of higher-order  waveguide modes to extract angle-error-sensing difference signals. There are many  tradeoffs in feed design because optimum sum and difference signals, low sidelobe  levels, selectable polarization capability, and simplicity cannot all be fully satisfied  simultaneously. The term simplicity  refers not only to cost savings but also to the use  of noncomplex circuitry, which is necessary to provide a broadband system with good  boresight stability to meet precision-tracking requirements. 
 TO 
 4. 18. W. 
 Golino, and L. Timmoneri, “Comparison between LS and TLS in adaptive process - ing for radar systems,” Proc. of IEE , vol. 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars.  SPACE-BASED REMOTE SENSING RADARS  18.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 ENVISAT.  The advanced SAR21 (ASAR) aboard ESA’s Envisat takes  RADARSAT-1’s versatility one step further, with the addition of two polarizations,  H and V, on either transmit or receive. 
 STATE SYSTEMS  DIODES ARE USED AND CAN BE SWITCHED IN A FRACTION OF A MICROSECOND $IODE 0HASE 3HIFTERS n $IODE PHASE SHIFTERS ARE TYPICALLY DESIGNED BY USING  ONE OF THREE TECHNIQUES   SWITCHED 
 3ALDANA  * * 7 7ILSON  % !TTEMA  2 'ELSTHORPE  - 2 $RINKWATER  AND ! 3TOFFELEN   h4HE ADVANCED SCATTEROMETER !3#!4  ON THE METEOROLOGICAL OPERATIONAL -ET/P  PLATFORM  A FOLLOW 
 POINTING ANGLE IS   PPP P244 42 4, 22 , 
 21,   no. 6, part 2 of 2, pp. 27–56, June 2006. 
 marker (M-scope). FIQ.6.2.—Range scopes. Each displays adelayed, expanded, range interval. 
 METEOROLOGICAL RADAR  19.416x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 REFERENCES  1. R. J. 
 PROCESSING RANGE RESOLUTION AND BY THE AMOUNT OF AVERAGING AVAILABLE FOR EACH ESTIMATE .OTE THAT A PRECISION MEASUREMENT MAY STILL HAVE POOR ACCURACY  IF ITS MEAN VALUE IS BIASED AWAY FROM THE CORRECT VALUE 7HEN COMPARING TWO NEIGHBORING HEIGHT MEASUREMENTS  ANY CONSTANT BIAS IS CANCELLED BY SUBTRACTION AS LONG AS THE ERROR IS THE SAME FOR BOTH MEASUREMENTS 4HE SEA 
 As the time-bandwidth product is increased, the model rec- tangular spectrum with parabolic phase is approached, and the sidelobe level in the absence of doppler shift approaches -40 dB. Unless SAW compression networks that compen- sate for the nonideal spectrum are employed, equalization techniques described later in this section are needed when sidelobe levels lower than about -30 dB are required. In Fig. 
   AFTER $ # 3CHLEHER Ú )%%%  . 
 14.6 Frequency control-loop gain.DOPPLER FREQUENCY (kHz) FIG. 14.7 Transmitter noise spectra: A, free- running FM; B, closed-loop FM; C, free- running FM divided by control-loop gain.GAIN(dB) SPECTRALDE(MSlTY PER Hz BANDWIDTHWB BELOW CARRIER) . at least 3 dB quieter at each offset frequency than the phase noise indicated by the instrumentation. 
 The effective beam  footprint (after doppler processing) is ∼0.5 km along track and ∼5 km across track.  Nominal SNR with respect to the surface return is in excess of 50 dB. Instrument mass  is ∼17 kg, input power is ∼45 W. 
 FADING CASE "ROKEN 
 UO 131  Frrors:  in at ray antennas. 318 322  in rcnector antennas. 262--264  Fvaporation duct. 
 Land surfaces are much more  difficult to describe: Imagine an adequate mathematical description of the shape of a  forest (when every leaf and pine needle must be described). Furthermore, land surfaces  are seldom homogeneous either horizontally or with depth. Since a true mathematical description of the ground surface appears out of the ques - tion, empirical measurements are necessary to describe the radar return from natural  surfaces. 
 At microwave frequencies and below, the relationship  between the index of refraction, n, and refractivity, N, for air that contains water vapor  is given as  N np Te Ts= − = +×( ). .1 10776 3 73 1 065 2 (26.2) where es is the partial pressure of water vapor in millibars or  erh e sx =6105 100. (26.3)  xT TT e =−−   252227325 312732... 
 KM SWATH  AND  M  
 27 forward scatter, 23. 21 glint in, 23.20 to 23.21 ground echo, 16.29 hitchhiker, 23.10 with noncooperative transmitter, 23.29 to 23.31 ovals of Cassini, 23. 6 to 23.8 passi ve, 23.10 pseudo-monostatic region, 23.19 to 23.20 pulse chasing, 23. 
 Examples include RADARSAT-2, ENVISAT’s ASAR,  PALSAR, COSMO, TerraSAR-X, and RISAT. It is argued that active arrays set the  stage for “graceful failure” since the loss of a few T/R elements would have little effect  on the net performance of the system. In parallel, an alternative SAR antenna paradigm  stresses simplicity and lower mass (and lower cost) over two-dimensional electronic  beam steering. 
 382 INTRODUCTION TO RADAR SYSTEMS  that can be employed wit.h phased:-array radar. 39·42 The radar transmits a pulse or.a series of  pulses in a particular direction as in an ordinary radar, except that the false alarm probability  is slightly higher than would normally be used. If no threshold crossings are obtained, the  antenna beam moves to the next angular position. 
  CSCD   "EL  = AND 2SWATH a 2MAXSWATH                  WHERE K IS TRANSMITTED WAVELENGTH  H IS THE AIRCRAFT ALTITUDE  "AZ  "EL ARE THE AZIMUTH  ELEVATION HALF POWER BEAMWIDTHS  P  D ARE THE ANGLES BETWEEN THE VELOCITY VECTOR AND ANTENNA BEAM CENTER  2 IS THE DISTANCE TO THE FIRST RANGE BIN  6A IS THE AIRCRAFT VELOCITY  2SWATH IS THE RANGE SWATH LENGTH  2MAXSWATH IS MAXIMUM INSTRUMENTED RANGE SWATH  2MIN IS THE RANGE TO THE CLOSEST ALLOWABLE AMBIGUITY  $UTYMAX IS ALLOWABLE DUTY RATIO  2P IS THE TRANSMITTED PULSE LENGTH IN DISTANCE UNITS  C IS THE VELOCITY OF LIGHT  5  5 ARE BEAMWIDTH MULTIPLIERS AT PREDEFINED POWER ROLLOFF&)'52%  3!2 -ULTIRATE &ILTERING ADAPTED COURTESY 3CI4ECH 0UBLISHING  . x°În  2!$!2 (!.$"//+  &OR EXAMPLE  ASSUME  6A    MS   K    M  H    M   P      D     "AZ    "EL     5  5     2SWATH    KM  2MIN   KM  DESIRED MAPPING RANGE   2    KM   $UTYMAX     SELECTING A FIRST GUESS FOR  2P    M THEN     02)     MSEC   2MIN IS THE EQUIVALENT OF   MSEC  AND THE NEXT ALLOWABLE AMBIGUITY WOULD BE PAST THE  SWATH AT   MSEC THEREFORE  A 02) OF  OR   MSEC COULD BE USED WITH A TRANSMITTED  PULSE OF APPROXIMATELY  OR  MSEC RESPECTIVELY 'ROUND -OVING 4ARGET )NDICATION '-4)  AND 4RACK '-44   '-4) IS  THE DETECTION AND ACQUISITION OF GROUND MOVING TARGETS '-4) AND '-44 RADAR  MODES HAVE A DIFFERENT SET OF CHALLENGES &IRST  TARGET DETECTION IS USUALLY THE EASY PART THE 2#3 OF MOST ANTHROPOGENIC OBJECTS AND MANY NATURAL MOVING TARGETS IS LARGE n M   5NFORTUNATELY  THERE ARE MANY STATIONARY OBJECTS WITH MOVING  PARTS SUCH AS VENTILATORS  FANS  WATER COURSES  AND POWER LINES THAT LEAD TO APPARENT FALSE ALARMS  /FTEN SLOW 
 DELAY CANCELER   AND C  THREE 
 However, the sea echo is a large signal, and it can be obtained with an adjunct oblique sounder operating in an appropri- ate radar mode. In summary, the sea echo power in a resolution cell (1) is generally the largest in-band echo signal; (2) generally exists in the open ocean even in relative calm; (3) varies as the square of resonant waveheight, which is frequently limiting at the higher frequencies; and (4) varies with direction, being greatest for seas running toward or away from the radar. 24.6 RADARCROSSSECTION The RCS of the sea has been treated in Sec. 
 Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 21.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 flat, cylindrical, or conical in cross section, forming a V structure in which radiation  propagates along the axis of the V structure. Although resistive termination is used,  this type of antenna has a directivity on the order of 10–15 dB depending on size;  hence, useful gain can still be obtained even with a terminating loss on the order of FIGURE 21.19  E-plane plot of far-field power density of a current element  radiating into a lossless material of dielectric constant of 900 −1 −1−2 −2 −20 1 2 2−3 −4−4 Horizontal distance in arbitrar y unitsDepth in arbitrary units FIGURE 21.20  H-plane plot of far-field power density of a current  element radiating into a lossless material of dielectric constant of 900 −1 −1−2 −2 −20 1 2 2−3 −4−4 Horizontal distance in arbitrar y unitsDepth in arbitrary units ch21.indd   28 12/17/07   2:51:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 PONENTS v )%%% 4RANS  VOL !0 
 1996 ,32, 1191–1197. [ CrossRef ] 18. Zhu, Z.; Qiu, X.; She, Z. 
 A low-PRF radar is one in which the ranges of interest  are unambiguous while the radial velocities (doppler frequencies) are usually highly  ambiguous. As discussed previously, this type of radar is called moving target indica - tion (MTI) . MTI radars are generally not categorized as pulse doppler radars, although  the principles of operation are similar.13 ch04.indd   2 12/20/07   4:51:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Critical . applications are usually only the front-end switching configurations in a trans- ceiver module, i.e., before the receive low-noise amplifier or after the transmit amplifier. PHASE SHIFTERS. 
 NOUNCED NULLS CAN BE EXPERIENCED  AND FOR USERS  IT CAN BE DISCONCERTING WHEN A TARGET CLEARLY EVIDENT FROM THE BRIDGE WINDOW IS NOT VISIBLE ON THE RADAR DISPLAY  DESPITE THE APPARENTLY GOOD CONDITIONS 3INCE SMOOTH SEAS CAN ALSO BE ASSOCIATED WITH MIST AND FOG  VER TICAL LOBING EFFECTS  CAN BECOME A SIGNIFICANT PROBLEM BECAUSE THE REDUCED VISIBILITY MEANS THAT RADAR OFTEN BECOMES THE SOLE METHOD OF DETECTING OTHER VESSELS 4HE ABSENCE OF SEA CLUTTER GIVES THE USER A FALSE SENSE OF SECURITY THAT ALL TARGETS WILL BE EASILY VISIBLE /N SHIPS FITTED WITH BOTH  AND  '(Z RADARS  FREQUENCY DIVERSITY BECOMES VERY USEFUL AS THE SPATIAL  FREQUENCIES OF THE VERTICAL LOBES FOR THE RADAR ARE DIFFERENT 3URPRISINGLY  EVEN THOUGH  SOME RADAR COMPANIES PROVIDE THE OPTION  VERY FEW SHIPS HAVE FACILITIES THAT ALLOW THE  
 COST REMOTELY PILOTED VEHICLES MIGHT BE PRACTICAL THEY CAN ASSIST STRIKE AIRCRAFT OR MISSILES IN PENETRATING RADAR 
 The entire time-frequency record of the pulsar’s main pulse can be presented as a wideband signal. Each frequency component preserves time delay and, respectively, phase components induced by the object crossing the pulsar emission beam. The algebraic sum of all monochromatic components in frequency channels determines a sinc function with maximum in the position of a particular reemitting scattering point of the space object. 
 The feedback must be eliminated if the traveling-wave amplifier is to function satisfactorily.  Energy traveling in the backward direction may be reduced to an insignificant level in most  tubes by the itisertiotl of attenuation in the slow-wave structure. The attenuation may be  distributed, or it may be lumped; but it is usually found within the middle third of the tube. 
 SATION IN THE LATTER CASE IS DEPENDENT ON THE PARTICULAR SYSTEM PARAMETERS &)'52%   -4) IMPROVEMENT FACTOR FOR A  STEP 
 ART SAMPLING RATES AND DYNAMIC RANGE !NALOG TO DIGITAL CONVERTERS TRANSFORM CONTINUOUS TIME ANALOG SIGNALS INTO DISCRETE  TIME DIGITAL SIGNALS 4HE PROCESS INCLUDES BOTH SAMPLING IN THE TIME DOMAIN  CONVERT 
 ETERS AFFECT THE AMPLITUDE OF THE REFLECTED SIGNAL #LUTTER ! MAJOR DIFFICULTY FOR OPERATION OF '02 SYSTEMS IS THE PRESENCE OF  CLUTTER WITHIN THE MATERIAL  #LUTTER IS DEFINED AS SOURCES OF UNWANTED REFLECTIONS THAT  OCCUR WITHIN THE EFFECTIVE BANDWIDTH AND SEARCH WINDOW OF THE RADAR AND PRESENT AS SPATIALLY COHERENT REFLECTORS 4HE DEFINITION OF CLUTTER VERY MUCH DEPENDS ON THE WANTED TARGET 4HE OPERATOR OF A '02 SYSTEM SEARCHING FOR PIPES MAY CLASSIFY THE INTERFACES BETWEEN ROAD LAYERS AS CLUTTER  WHEREAS THE OPERATOR OF A SYSTEM MEASURING ROAD LAYER THICKNESS MIGHT CONSIDER PIPES AND CABLES AS SOURCES OF CLUTTER #AREFUL DEFINITION AND UNDERSTANDING ARE CRITICALLY IMPORTANT IN SELECTING AND OPERATING THE BEST SYSTEM AND PROCESSING ALGORITHMS #LUTTER CAN COMPLETELY OBSCURE THE BURIED TARGET AND A PROPER UNDERSTANDING OF ITS SOURCE AND IMPACT ON THE RADAR IS ESSENTIAL 0OLARIZATION ! COMPLETE DESCRIPTION OF THE RADAR SCATTERING CROSS SECTION OF  A TARGET INCLUDES A DESCRIPTION OF ITS POLARIZATION SCATTERING CHARACTERISTICS NOT THE  SAME AS MOLECULAR POLARIZATION  4HE POLARIZING PROPERTIES OF TARGETS ARE DESCRIBED  BY THE 3TOKES PARAMETERS  AND THE POLARIZATION COORDINATES CAN BE REPRESENTED ON THE 0OINCARE 3PHERE !LL OF THESE ARE WELL DESCRIBED IN STANDARD TEXTS ON OPTICS AND ELECTROMAGNETIC THEORY )N SUMMARY  THESE DESCRIPTIONS ALLOW THE STATE OF AN ELECTRO 
 13.2. The incidence  angle is defined relative to the normal to the surface; the grazing angle is defined with respect to  the tangent to the surface, and the depression a11gle is definecj with respect to the local horizon­ tal at the radar. When the earth's surface can be considered flat, the depression angle and the  grazing angle are the same. 
 97. Millimeter Waveguide Systems. Microwave J., vol. 
 PURPOSE WAVEFORM  ABLE TO SUPPORT TWO DISTINCT MISSIONS  THOUGH WITH SUBOPTIMAL PERFORMANCE  OR FOR THE TRANSMIT SYSTEM TO RADIATE MULTIPLE ORTHOGONAL WAVEFORMS FOR SIMULTANEOUS RECEPTION AND PROCESSING AT A PROPORTIONAL LOSS OF AVERAGE POWER ON EACH TRANSMISSION BUT WITHOUT LOSS OF SPATIAL DIRECTIVITY "UT EVEN IF THESE APPROACHES ARE SOMETIMES APPLICABLE  IT IS ALMOST ALWAYS NECESSARY TO SCHEDULE THE VARIOUS TASKS SUCH THAT ACCEPTABLE REVISIT TIMES ARE MAINTAINED ON IMPORTANT MISSIONS  WITH LOW PRIORITY TASKS  SUCH AS WEATHER MONITORING  ACTIVATED LESS FREQUENTLY  AND CHALLENGING TASKS ACTIVATED WHEN SUITABLE PROPAGATION CONDITIONS OCCUR  /NE OTHER IMPORTANT ISSUE ARISES WITH RESOURCE MANAGEMENT AND THAT IS THE ABIL 
 Asdata transmitters they areoccasionally used forpurposes ofpre-time-base resolution onslowly scanning systems, orasabasis ofinformation forcomputers. Variable Transformers (Resolvers, Synchros, etc.).—Figure 13.6a illus- trates theprinciple ofcertain variable transformers called “resolvers,” ‘‘synchros, ““selsyns, ““autosyns, ”and soon,which are widely used asposition-data transmitters. Aniron-cored coil (rotor) ofspecial shape ismounted onafreely turning axis inside aslotted-iron framework much likeamotor stator. 
 I, pp. 48-50.  86. 
 Fundamental Accuracy of Sequential Lobing. Sequential lobing is a tech- nique used in radar for estimating the angle of arrival of electromagnatic radiation incident on an antenna by comparing the amplitudes of the received echoes in two or more sequentially formed or selected antenna beams. The technique is used for height finding by time—sequentially scanning a beam in elevation while transmitting and receiving pulses in each beam position. 
 19, pp. 297-301, April, 1965.  30. 
 22.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 Solid-state CMR.  Several factors have come together to promote the introduc - tion of civil marine radars with solid-state transmitters. The most important of these  is that affordable magnetron-based radars do not meet user demands when operating  in heavy sea and precipitation clutter. 
 }Ve leave this task tothe reader, \rho will find nodifficulty incalculating, forany given case, thereduction inrange caused byaspecified strength ofattenuation, which iseffective, of course, onboth theoutgoing and return path. One general observation should bemade, however, which isthat theeffect ofanexponential term inthe radar equation isinsignificant atvery short ranges but over- whelming atvery long ranges. What wemean byshortand longis determined bytherate ofattenuation. 
 Theoutputofthephase-sensitive detector is. Figure 5.7 Monopulse antenna patterns and error signal. Left-hand diagrams in (a-c) are in polar coor-  dinates; right-hand diagrams are in rectangular coordinates. 
 advanced 90° and added to that of mixer 2, the signals will sum in the combiner and disappear in the differencer. A corresponding diagram would show that receding tar- gets reinforce in the differencer and cancel in the combiner. An advantage of the quadrature system is that the filter bands are completely symmetrical and all filter elements may be identical. 
 EDGE RESEARCH REQUIRES MORE DETAILED AND MORE SENSITIVE MEASUREMENTS OF A MULTIPLICITY OF VARIABLES SIMULTANE 
 A VS waveform is used with a low detection threshold and a corresponding  false alarm time on the order of a few seconds. The lower detection threshold increases  sensitivity. When an Alert dwell declares a detection, a Confirm dwell is scheduled  for that Alert dwell’s beam position. 
 The goal  is to preserve the desired signal while simultaneously reducing unwanted interference.  This real-time antenna pattern control is accomplished by adjusting the weights at each  receiver to maximize signal-to-interference-plus-noise ratio. The amplitude and phase  weight for the signal at each receiver is adaptively computed and implemented so that the  desired signal combines coherently whereas the interference combines incoherently. 
 To obtain sidelobes at levels −45 dB down  from the main beam (average level, below −20 dB), the total phase-error budget  is required to be in the order of 5 ° rms or less. This is difficult in arrays that elec - tronically scan: the errors induced by phase shifters, active components, and feed  elements must be included in this budget. Arrays have been realized in practice that  have peak sidelobes in the vicinity of the −45 dB level; however, these are generally  mechanically scanned, and the low error budgets are achieved by using all-passive  feed components. 
 Table 2.2 lists "example" values of cross section for various targets at microwave  frequencies. Note that only a single value is given even though there can be a large variation.  They should not be used for design purposes when actual data is available for the particular  targets of interest. 
 J. Palermo, and L. J. 
 RANGE AIRBORNE SURVEILLANCE AND TRACKING OF STA 
 Unfortunately, in- creasing P to increase ks also increases the loss Lk, which reduces the SNR. The relative values of ks and Lk depend upon whether the target provides a beacon response that removes the transmitting modulation from the received sig- nal or whether two-way skin tracking is performed. Two-way tracking gives a greater depth of modulation, or angle sensitivity, for a given p but doubles the loss in decibels. 
 J. Mailloux, Phased Array Antenna Handbook , Norwood, MA: Artech House, 2005. 106. 
 NOISE AMPLIFI 
 Changes in  transmitter frequency affect the echo signals in the two directions equally and are therefore  canceled when taking the difference frequency.  Another method of achieving the necessary isolation in a doppler-navigation radar is  with a sinusoidal frequency-modulated CW system. By frequency-modulating "the transmis­ sion, the leakage signal may be reduced relative to the signal from the ground by extracting a  harmonic of the modulating frequency and taking advantage of one of the higher-order Bessel  functions as described in the previous section. 
 However, at other angles, the radar detection range can be less than the free-space range.  When the target lies in the nulls, no echo signal is received.  The angle (in radians) of the first (lowest) lobe is approximately equal to ,l./4h.,. 
   PP n  *ULY   * "LASS  h4HE MULTIDIRECTIONAL ANTENNA ! NEW APPROACH TO STACKED BEAMS v IN  )2% )NT #ONV  2EC  VOL  PT     PP n  ( 'ENT  4HE BOOTLACE AERIAL  2OYAL 2ADAR %STAB * 5+   PP n  /CTOBER  7 2OTMAN AND 2 & 4URNER  h7IDE ANGLE MICROWAVE LENS FOR LINE SOURCE APPLICATION v  )%%%  4RANS  VOL  !0 
 TION ZONE BUT IS THERE TO PROVIDE AN ALARM IF ANY TRACKED TARGET PASSES INTO THE ZONE )N COMMON WITH OTHER RADAR TRACKERS  STRATEGIES HAVE TO BE EVOLVED TO COPE WITH  THE TARGET BEING POTENTIALLY INVISIBLE IN SOME SCANS )-/ REQUIRES THAT THE SPECIFIED PERFORMANCE IS MAINTAINED WHEN THE TARGET IS INVISIBLE IN UP TO  OF SCANS !LSO  FOR  AN EFFECTIVE SYSTEM  STRATEGIES HAVE TO BE EVOLVED TO REDUCE THE POSSIBILITIES OF TARGET  IDENTITIES BEING SWAPPED  WHICH CAN HAPPEN WHEN TARGETS MOVE CLOSE TOGETHER AND SUBSEQUENTLY DIVERGE )N PARTICULAR  TRACKING ALGORITHMS HAVE TO ATTEMPT TO COPE WITH THE POTENTIALLY LARGE AND FAST CHANGE IN THE RADAR CENTROID AS A TARGET VESSEL TURNS )N THE WORST CASE  THIS CAN AMOUNT TO ALMOST THE LENGTH OF THE VESSEL   METERS OR SO  FOR A LARGE SHIP )T IS AN ART TO GET A GOOD TRACKER OPTIMIZED FOR ALL SITUATIONS  OVER A VARIETY OF VESSEL SPEEDS  AND TO MAINTAIN AN APPROPRIATE INDICATION OF CHANGE IN HEADING WITHOUT EXCESS LATENCY /VER 
 RATE OUTPUT /F COURSE  THE &)2 FILTER MUST BE CLOCKED AT THE HIGHER DATA RATE 4HIS PROCESS IS ILLUSTRATED IN &IGURE  FOR A FOUR TIMES INCREASE IN SAMPLE RATE&)'52%     
 Fresh water has  a relative dielectric constant of approximately 80. It should be noted that the ground  and surface are quite likely to be inhomogeneous and contain inclusions of other rocks  of various size as well as manmade debris. This suggests that the signal to clutter per - formance of the sensor is likely to be an important performance factor. 
 RAY EMISSIONS REQUIRE NO PERSONNEL TO OPERATE BE OF AN AFFORDABLE PRICE AND BE OF REASONABLE SIZE AND WEIGHT FOR THE DESIRED APPLICATION /F COURSE  NOT ALL OF THESE DESIRABLE ATTRIBUTES CAN BE ACHIEVED IN ANY GIVEN RADAR TRANS 
 A major difficulty for operation of GPR systems is the presence of  clutter within the material. Clutter  is defined as sources of unwanted reflections that  occur within the effective bandwidth and search window of the radar and present  as spatially coherent reflectors. The definition of clutter very much depends on the  wanted target. 
 02& WAVE 
 27, February 1926.  2. L. 
 E. Hamilton, and F. L. 
 It is difficitlt to design a  repeater jammer that will play back an exact reproduction of the radar signal. The radar echo  from a target can be considered as being linear, but the signal from a repeater is generally not > linearly related to that which was transmitted by the radar. Thus one strategy for defeating  repeater jamming is to utilize radar transmissions with a form of identification difficlrlt to  mimic by the "nonlinear" repeater. 
 41. K. M. 
 Radar reflectors are normally used to shape and distribute energy, which is more complicated than the case of the symmetrical paraboloidal reflector. Thus, where the focused paraboloid re- flects into a common plane over the en- tire reflector, the shaped reflector fo- cuses into many planes and the most general analysis is to treat the problem as an incremental summation of E fields. Another advantage of this analysis method is that the reflector outline can also be most general. 
 Today TACCAR is used to describe the centering of the returned clutter spectrum to the zero filter frequency. Since the technique compensates for drift in the various system elements and biases in the mean doppler frequency due to ocean currents, chaff, or weather clutter, it is used in shipboard and land-based radars as well as airborne radar. A functional block diagram of an airborne radar employing TACCAR is shown in Fig. 
 The signal processor , which is often in the  IF portion of the receiver, might be described as being the part of the receiver that  separates the desired signal from the undesired signals that can degrade the detec - tion process. Signal processing includes the matched filter  that maximizes the out - put signal-to-noise ratio. Signal processing also includes the doppler processing that  maximizes the signal-to-clutter ratio of a moving target when clutter is larger than  receiver noise, and it separates one moving target from other moving targets or from  clutter echoes. 
 See correction, AES-10, p. 168, January, 1974.  46. 
 '303 DIRECT DIGITAL SYNTHESIZER DATA SHEET  2EV !    !NALOG $EVICES  .ORWOOD   -! AVAILABLE AT WWWANALOGCOM   * + (ARTT AND , & 3HEATS  h!PPLICATION OF PIPELINE &&4 TECHNOLOGY IN RADAR SIGNAL AND DATA  PROCESSING v  %!3#/. 2EC    PP n REPRINTED IN $AVID + "ARTON   2ADARS  VOL     !NN !RBOR "OOKS ON $EMAND 5-)    0 % "LANKENSHIP AND % - (OFSTETTER  h$IGITAL PULSE COMPRESSION VIA FAST CONVOLUTION v  )%%% 4RANS ON !COUSTICS  3PEECH AND 3IGNAL 0ROCESSING   VOL !330 
 55. Drukey, D. L., and L. 
 The doppler-shifted return signal, when added tothetransmitter voltage and rectified, gives rise toavoltage with small pulsations recurring atthe doppler fre- quency. The steady component isremoved bythe highpass filter, which may besimply atransformer oraseries condenser. The fluctuations areamplified and used toactuate the indicator. 
 AP-4, pp. 162-167, April, 1956.  72. 
 D" POINTS OF THE  ANTENNA PATTERN 4HIS EQUATION WAS DERIVED FROM A GAUSSIAN BEAM  SHAPE BUT IS ESSEN 
 Thebasicpower-generating unitcomesina relatively small size;hence,manyunitshavetobecombined. insomemanner toachieve thepowerlevels required forradar.Thehigherthefrequency, thelessthepoweravailable fromanindividual solid-state deviceandthemoredifficult willbethecombining problem becauseofthelarger number ofdevicesrequired. Atthelowermicrowave frequencies, thetransistor isoneofthe betteravailable solid-state sources. 
 The value previously used for scanning 60 ° was K = 1 and this value appears  acceptable here, where the relevant beamwidth is the broadside beamwidth of the  subarray. Thus, if the aperture is split into N subarrays in one plane, with time-delay  networks at each subarray level, the bandwidth is increased by a factor of N. This same  bandwidth criterion leads to a reduction in gain of about 0.7 dB and a grating lobe of  about −11 dB at the edges of the band with 60 ° of scan. 
 The phase across the  aperture is such that the individual composing patterns are displaced from one another by a  half a beamwidth (where the beamwidth is here defined as the distance between the two nulls  which surround the main beam). The phase is given by the exponential term of ~q. (7.27) and  represents a linear pliase change of 111r radians across the aperture. 
 LEVEL VARIABILITY AND THE  4!",%  !LTIMETERS 3PACECRAFT #OUNTRY 9EAR 2EPEAT )NCLINATION !LTITUDE 3PACING "AND(/  CORRECTION!CCURACY DAYS DEGREES KM KM CM 3KYLAB   53!  .O ^  NA +Un  M '%/3 
 10. M. Skolnik, D. 
 Speciﬁcally, the dashed rectangles represent the actual observation areas of PALSAR on ionosphere at 300 km, i.e., the coverage of PALSAR beam on the ionosphere at 300 km. Therefore, we know that the distance from each observation area to its ground scene center is around 100 km and that the TEC obtained from PALSAR is slant TEC rather than vertical TEC (VTEC). The VETC should be estimated as VTEC =TEC×cosη, (10) 204. 
 Fortunately, the timeline for opening targets is much longer (net speed is less) and the  engagement range is much shorter (weapon closure rates are too slow). Often in general search, MPRF-VRS (medium PRF velocity-range search) is  interleaved with HPRF VS and RWS, as shown in Figure 5.20, to provide all aspect  detection. Unfortunately, both RWS and VRS have poorer maximum detection range. 
 TRACKING ERRORS &)'52%     #ONICAL 
 Since the voltage across Cocannot change instantaneously, thepoint A’ will assume ahigh negative voltage, which isapplied totheload. Cur- rert will continue toflow outofCO,and around theload circuit, until the driving pulse onthegrid ofT,isremoved. The system will return toits. 
    
 [ CrossRef ] ©2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). 
 The probability that the ;ignal will be detected (which is the probability ofdetenio,,) is the  same as the probability that the envelope R will exceed the predetermined threshold VT. The  26INTRODUCTION TORADAR SYSTEMS ,yeor 15min-.6months 15 9 10.t112 13 14 Threshold-to-noise ratioV,Y2iJ.to, dB0.1'--__ L.-L__ L-L.__<--_-L-J_...L---I_...L-----' __ ----' 8',000 30days .J::.2weeks- h.~ VI -1week E100L-a 0 3doys <I.> VI2days0.... <:: a.>1day a.> ~.-a.>.012ha.>10E.+= a.> 0- 0L- a.> :> <l 1h Figure2.5Average timebetween falsealarmsasafunction ofthethreshold levelV,andthereceiver bandwidth B;"'0isthemeansquarenoisevoltage. 
 ROUTE SURVEIL 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°xÎ &)'52%  2ADAR DETECTIONS  O AND $& DETECTIONS COLLECTED ON THE CONTROL AIRCRAFT 4HE  OS   $S   S  AND  XS ARE RADAR DETECTIONS ON FOUR AIRCRAFT OF OPPORTUNITY IN THE VICINITY OF THE CONTROL  AIRCRAFT AFTER '6 4RUNK AND *$ 7ILSON Ú )%%%   &)'52%   !SSOCIATION PROBABILITIES FOR EXPERIMENTAL DATA 4HE BOLD LINES ARE PROBABILITIES FOR  THE CONTROL AIRCRAFT THE SOLID LINE  FOR LIMITING THE DASHED LINE  FOR NO LIMITING THE THIN LINE  THE ASSO 
  D" WITH A PROBABILITY OF  4HE PROCESS OF  CONTROLLING EACH AND EVERY SIDELOBE IS THUS SEEN AS FORMIDABLE  SINCE THE TOTAL NUM 
     %'"-%$) # !')"  # ))!# )"+! %,!'. £È°xÓ  2!$!2 (!.$"//+  4HE ACTUAL NUMBERS FOR THE COPOLARIZED RESPONSE FOR THIS CASE ARE  B   n 66  AND  X    n 4HE REFERENCE PRESENTS SIMILAR PLOTS SHOWING SEPARATELY THE POLARIZED AND  UNPOLARIZED RESPONSES "ECAUSE OF THE COMPLEXITY OF THIS REPRESENTATION AND OTHERS FOR POLARIMETRIC SIGNALS   ONE CANNOT AS READILY PROVIDE CURVES OF RESPONSE AS FOR SINGLE 
 BANDWIDTH PULSE COMPRESSION PROCESSING IS  PERFORMED IF THE REFERENCE WAVEFORM ,&- SLOPE IS LESS THAN THE TRANSMIT WAVEFORM ,&- SLOPE @ 2   @    )N BOTH CASES  THE REQUIRED PROCESSING BANDWIDTH  "P IS MUCH  SMALLER THAN THE WAVEFORM BANDWIDTH  &IGURE  SHOWS THE PRINCIPLE OF STRETCH PULSE COMPRESSION FOR THE CASE WHERE THE  ,&- SLOPES OF THE TRANSMIT AND REFERENCE WAVEFORMS ARE EQUAL 4HE INSTANTANEOUS FRE 
 ENCES  WHICH NEED TO BE APPRECIATED WHEN COMPARING THEM WITH CONVENTIONAL RADAR SYSTEMS '02 SYSTEMS ARE A SPECIAL CLASS OF ULTRAWIDEBAND 57"  RADAR SYSTEM AND CAN RADIATE ENERGY IN THE RANGE OF FREQUENCIES FROM A FEW -(Z UP TO  '(Z WITH A BANDWIDTH OF UP TO A DECADE  BUT MORE  USUALLY n OCTAVES 4HE  TYPICAL AVERAGE RADI 
 Conventional vibrators, such asthose used commercially inautomobile radios, are capable of supplying 50to60watts ofsquare-wave alternating current toatrans- former. The transformer output may berectified and filtered tofurnish direct current ofappropriate voltage. Vibrator power supplies can, unlike dynamotors, supply anumber of different d-c output voltages without disproportionate increase inthe weight ofthe power supply. 
 TO 
 OF 
 Radar System Engineering  Chapter 1 – History of Radar Technology  3     As was first shown by Hertz, electric waves can be co mpletely ref lected by  conducting bodies. In some of my tests I have noticed the effects of reflection and  detection of these waves by metallic objects miles away. It seems to me that it  should be possible to design apparatus by means of which a ship could radiate or  project a divergent beam of these rays in any desired d irection, which rays, if  coming across a metallic object, such as another steamer or ship, would be  reflected back to a receiver screened from the local transmitter on the sending  ship, and thereby, imm ediately reveal the pre sence and bearing of the other ship  in fog or thick weather. 
 H. Jelin: A Study of Radar Elevation-arigle Errors Due to Atmospheric  Refractinri. IRE Trarrs.. 
 MOUNTED  
 TIME MONITORING OF %L .I¶O EVENTS  WHOSE HEIGHT SIGNATURE OVER THE EQUATORIAL EASTERN 0ACIFIC OCEAN TYPICALLY IS AN INCREASE ON THE ORDER OF n CM WITH RESPECT TO THE MEAN 0OSEIDON  CONTRIBUTED BY &RANCE  WAS A SMALL PROOF 
 ING A FALSE TARGET PRODUCED BY A JAMMER ENTERING THROUGH THE RADAR SIDELOBES  0&4 IS  THE PROBABILITY OF ASSOCIATING  U  V  WITH ( WHEN ( IS TRUE IT IS A FUNCTION OF *.2   THE THRESHOLDS  @ AND &  AND THE GAIN MARGIN  A V  4HE PROBABILITY  04" OF BLANKING  A TARGET RECEIVED IN THE MAIN BEAM 4HIS IS THE PROBABILITY OF ASSOCIATING  U  V  WITH  ( WHEN ( IS THE TRUE HYPOTHESIS  04" IS RELATED TO 3.2   &  AND THE AUXILIARY GAIN   W   '!'T NORMALIZED TO THE GAIN  'T OF THE MAIN BEAM 4O COMPLETE THE LIST OF PARAM 
 Increased echoes from birds are to be expected during  migratory periods (spring and fall) and during those times of day when bird activity is large  (sunrise and sunset).  Birds typically fly at speeds of from 15 to 40 knots,92 and some can fly 50 knots or greater.  These speeds are usually too high to be completely rejected by most microwave MTI radars. 
  3YSTEM    4!",%  $ISCRETE ,EVEL 2EQUIREMENT #ALCULATION 0ARAMETER 6ALUE ;D"= 5NITS #OMMENT 4HERMAL .OISE 0OWER AT !$ 
 Unless weight and power consumption areextremely critical, thesaving effected does notjustify thesacrifice inquality entailed. 13.17. Resolved-current PPI.—When thedeflection coils aredriven directly bythe synchro, theamplifiers ofFig. 
 R. K. Moore, “Tradeoff between picture element dimensions and noncoherent averaging in side- looking airborne radar,” IEEE Trans. 
 / 4HE COMPLEXITY OF THE (& RADAR OPERATING ENVIRONMENTTHE IONOSPHERE  CLUTTER  NOISE  AND OTHER USERS OF THE BANDNECESSITATES A COMMENSURATE COMPLEXITY IN SYS 
 Figure α Γ0/υ Vmax Rotation Direction (a) 0.0204 10 π 0.68 m/s clockwise (b) 0.0272 10 π 1 m/s clockwise (c) −0.0272 10 π 1 m/s anticlockwise (d) 0.0272 12 π 1 m/s clockwise 2.2. SAR Image Simulation After the establishment of the eddy current ﬁeld, an oceanic SAR imaging simulation model was required for simulating SAR eddy images. For this purpose, we selected M4S,f which was developed by Roland Romeiser of the University of Hamburg, Germany. 
 LINE FLIGHT  PATH AT CONSTANT VELOCITY PARALLEL TO THE GROUND AT CONSTANT ALTITUDE 4HIS IS NOT EXACTLY  TRUE  AND FOR SUCCESSFUL 3!2 IMAGING  IT IS NECESSARY THAT THE DEVIATIONS OF THE ANTENNA FROM THIS NOMINAL FLIGHT PATH BE MEASURED  RECORDED  AND COMPEN SATED FOR IN THE PRO 
 CIENCY LOSS   SPILLOVER  AND BLOCKAGE  HAVE BEEN EXPLAINED IN DETAIL ABOVE 4HESE DESIGN PARAMETERS LOSS FACTORS  AFFECT ONE ANOTHER AND ARE OFTEN TRADED TO OPTIMIZE ANTENNA PERFORMANCE  EG  GAIN  SIDELOBES  ETC /THER TYPICAL REFLECTOR LOSSES  DESCRIBED LATER IN THIS SECTION  ARE RESISTIVE LOSS FACTORS THAT SIMPLY REDUCE THE ANTENNA GAIN 4HE DESIGN TRADES ASSOCIATED WITH TAPER EFFICIENCY  SPILLOVER  AND BLOCKAGE ARE  ILLUSTRATED BY USE OF AN EXAMPLE #OMPUTED LOSSES ARE SHOWN IN &IGURE  FOR A   
 EDGE  TRACKERS BY OBSERVING WHEN THE TARGET VIDEO EXCEEDS A GIVEN THRESHOLD LEVEL 4HE POINT OF CROSSING THE THRESHOLD IS USED TO TRIGGER GATING CIRCUITS TO READ OUT A TARGET RANGE FROM TIMING DEVICES OR TO GENERATE A SYNTHETIC TARGET PULSE 4HE RANGE 
 NENTS THAT DO THE TILTING AND SMALLER COMPONENTS THAT ARE "RAGG 
   #)6), -!2).% 2!$!2   ÓÓ°Ó THAT THE SYSTEM IS ADVERSELY AFFECTED IF SET UP CLOSE TO LARGE RADAR 
 Equations (1 1.52) and (1 1.53) describe  the behavior of the ambiguity function on the time-delay axis and the frequency axis, respec-  tively. Along the TR axis the function x(TR ,fd) is the autocorrelation function of the modula-  tion u(t), and along the f, axis it is proportional to the spectrum of u2(r). Equation (1 1.54)  states that the total volume under the ambiguity function is a constant equal to (2E)2. 
 Thus, the simulation focus on the imaging performance with different scintillation strength (from 1032to 1034as is shown in different rows) and different spectral index (from 2 to 5 as is shown in the x-axis of each line graph). The peak loss, PSLR and ISLR are counted and plotted as the line graph in different rows. The black spot represents the mean value of the statistical data and the vertical short lines represent the variation scope of the variables. 
 IBILITY 3#6   WIDELY USED IN (& RADAR AS A MEASURE OF SENSITIVITY AND DEFINED AS 2.  IS  D" IN THIS EXAMPLE )N MICROWAVE RADAR  THE TERM  SUB 
 On each scan, one-eighth of the output of  the zero-velocity filter is added to seven-eighths of the value stored in the map. Thus, the map  is built up in a recursive manner. About 10 to 20 scans are required to establish steady-clutter  v3Jues. 
   4AYLOR N     
 Oceanog ., vol. 20, December 1990. 74. 
   PP n  /CTOBER    h2ADAR CROSS 
 48. Schoenenberger, J. G., and J. 
 SANDWICH IS A THREE 
 However, the scattering by spheres surrounded by a con- centric film of different dielectric constant does not give the same effect that EXCESS PATH LOSS (dB/mi) . *From Burrows and Attwood.27 Ryde's results for dry particles would indicate.23'31 For example, when one-tenth of the radius of an ice sphere of radius 0.2 cm melts, the scattering of 10-cm ra- diation is approximately 90 percent of the value that would be scattered by an all-water drop. At wavelengths of 1 and 3 cm with 2a = 0.126 (a = radius of drop), Kerker, Langleben, and Gunn31 found that particles attained total-attenuation cross sec- tions corresponding to all-melted particles when less than 10 percent of the ice particles was melted. 
 DISCERNIBLE SIGNAL -$3  LEVEL OF THE RADAR BY  D" IS SHOWN IN &IGURE  B&)'52%   $ISTRIBUTION OF REFLECTIVITY FOR GROUND CLUTTER TYPICAL OF HEAVY CLUTTER AT 3 BAND  AFTER $ + "ARTON Ú )%%%   &)'52%   00) DISPLAY   
 TtfE RADAR EQUATION 33  repeated for each value of .)I and n.13 This is not done here. Instead, for simplicity, an efficiency  will be defined which is the ratio of tile average signal-to-noise ratio for the exponential  integrator to the average signal-to-noise ratio for the uniform integrator. For a dumped  integrator, one which erases the contents of the integrator after rr pulses and starts over, the  efficiencv isI4  /> = tanh (11~12)  11 tanh (712)  An exarnple of an integrator that dumps is an electrostatic storage tube that is erased whenever  it is read. 
 Radar Detection Theory, ONR Symp. Rept. ACR-IO, pp. 
 Randeu, “Advanced weather radar sys - tems in Europe: The COST-75 action,” Bull. Amer. Meteoro. 
 The phase of each transmitted binary element is 0° or 180° with respect to the LO signal. The phase of the received signal with respect to the LO signal, however, is shifted by an amount depending upon the target's range and velocity. Two processing channels are used, one which recovers the in-phase components of the received signal and the other which recovers the quadrature components. 
 F.: Effectiveness of Crosscorrelation Detectors, Proc. Natl. Electronics Conj. 
 This is accomplished by  separating the sidelobe clutter from the main-beam clutter by doppler filtering. The filtered  signal adaptively adjusts the aperture illumination to minimize the sidelobes in those direc-  tions from which clutter appears.  The col~ererir sitielobe cnttceler (Sec. 
 J. R. Duncan, and M. 
 Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.60  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16  91. F. 
 KM MEAN  EQUATORIAL ALTITUDE 2ADIAL KNOWLEDGE OF THESE SUN 
 Sensors 2020 ,20, 1851 17. Huang, X.; Ji, K.; Leng, X.; Dong, G.; Xing, X. Refocusing Moving Ship Targets in SAR Images Based on Fast Minimum Entropy Phase Compensation. 
 MIL-5, no. 2, pp. 127–131,  April 1961. 
 Stabilization ofthe Beam. Airborne Antenna Stabilization. 2— Antenna stabilization forairborne radar isascheme topreserve thesame conditions ofradiation illumination inponlevel flight asinlevel flight. 
 The radar equation can be manipulated into various forms, depending on the particular application. Several examples are given below. Tracking. 
 RECEIVE ANTENNA GAIN PRODUCT OF  D"  AND A TARGET AT  NMI WITH AN 2#3  OF  D"SM THEN THE RECEIVED POWER IS   0D " 7 R 
 BASED DUCT SKIP 
 9.12. These waffle-shaped frames require noribs for stiffening because the mating section conforms tothe contour ofthe back ofthe reflector face. Analuminum-alloy supporting bracket can beriveted to I .A FIG.9.12.—Rear view showing theconstruction ofane-ftairborne paraboloid trimmed toa 3-ftheight. 
 ATIONS UNIQUE TO THE AIRBORNE ENVIRONMENT Î°ÓÊ  "6 
    
 MIZING THE DEGRADATION DUE TO LIMITING !LL RADAR SYSTEMS CONTAIN SOME FORM OF 4RANSMIT2ECEIVE 42  DEVICE TO PROTECT  THE RECEIVE ELECTRONICS FROM THE HIGH 
 TUDE AND PHASE IMPOSED ONTO THE BACKSCATTERED FIELD SUPERSCRIPT  "  IN RESPONSE TO THE  ILLUMINATION FROM THE TRANSMITTED FIELD SUPERSCRIPT  4   ACCORDING TO THEIR RESPECTIVE  POLARIZATIONS 4HUS  THE SCATTERING MATRIX IS A QUANTITATIVE DESCRIPTION OF THE TRANSFOR 
 J. Anderson, “Experimental study of the spatial  dynamics of environmental noise for a surface-wave OTHR application,” Proc. 8th Int. 
 S. Washburn: Atmospheric Radio Noise: Worldwide Levels and Other Characteristics, NTIA Rept. 85-173, National Telecommunications and In- formation Administration, April 1985. 
 S. Ramo and J. R. 
 Instead of mount­ ing the antenna on a level platform, the antenna is tilted about the elevation axis so as  to automatically maintain the beam pointed at the horizontal. (The beam direction can also be  maintained constant at whatever angle above or below the horizon is desired.) The line of sight  is thereby stabilized.  The unsteady motions or the platform can cause errors in the angular measurement and  distortion of the data on indicators like the PPL Corrections can be applied in some cases to  account for these distortions. 
 The two are based  on the same physical principle, but in practice there are generally recognizable differences  between them (Sec. 4.10). The MTI radar, for instance, usually operates with ambiguous  doppler measurement (so-called hli11d speeds) but with unambiguous range measurement (no  second-time-around echoes). 
 The solar activity that drives the ionization of the earth's atmosphere is vari- able on a diurnal, seasonal, and long-term basis with a superimposed random component. Current prediction and analysis methods depend upon a statistical description of the ionosphere. A large amount of vertical-incidence reflection- height versus frequency-sounding (ionosonde) data has been collected over sev- eral decades, and from this data most descriptions of the ionosphere are derived. 
 The Magellan  antenna was used as the high-gain antenna for data downlink as  well as for the SAR. During the high-altitude segment of each orbit, the spacecraft  was oriented to point the antenna toward Earth. The antenna had two feeds, one at S  band (HH-polarization for the radar) and X band (circular-polarization for telemetry). 
 Since an incremental delay ∆t corresponds to an incremental downrange distance   ∆r = c∆t/2, we multiply the DFT output by c/2 and obtain the echoes corresponding  to a set of downrange distances separated by a pixel width of c∆t/2 = c/2B. Thus, the  range resolution (strictly speaking, pixel separation) of a step-frequency waveform  of bandwidth B is  δrc B=/2 (17.7) Although it is beyond the scope of this chapter, it can be shown that such a range  resolution of ≈ c/2B may be obtained using a wide variety of waveform types, as long  as the overall transmitted bandwidth is B. For example, Section 7.2 of Sullivan1 shows  that this is true for the LFM waveform. 
 If R is the distance from the radar to target, tile  total number of wavelengths L contained in the two-way path between the radar and the target  is 2RlA. The distance R and the wavelength L are assumed to be measured in the same units.  Since one wavelength corresponds to an angular excursion of 27~ radians, the total angular  excursion # made by the electromagnetic wave during its transit to and from the target is  4rtRlA radians. 
 In Figure 15, it is clear that vehicles, dihedrals, trihedrals, and the top-hat are clustered in different ranges. The ranges of different types are not coincident. The aspect entropy values of dihedral B and the trihedral are close in the simulation result so it is unclear whether the aspect entropy value can discriminate these two kinds 259. 
 whichismuchgreaterthanthetomsdecorrelation timequotedfor X-bandseaclutter.Thepersistence ofthesesea-clutter spikesmakesdifficultthedetection of smalltargets.suchasbuoysandsmallboats.Asingle"snapshot" ofaPPIwouldnotlikely differentiate theechoofasmalltargetfromthatoftheseaspikes.Theindividual seaspikes, however. willdisappear withtimeandnewspikeswillappearatotherlocations.Ifitispossible toobservetheradardisplayforasufficient periodoftime,thesmalltargetscanberecognized sincetheywillremainrelatively fixedinamplitude whiletheseaspikescomeandgo.The penaltypaidforthisprocedure isalongobservation time. Frequency agility.Ifthefrequency ofapulseoflength tischanged byatleastlit.theecho fromuniformly distributed clutterwillbedecorrelated. 
 // 
 Turn the contrast control clockwise until the grass is just visible as a speckling on the tube (with the scanner revolving). e. As a target is approached reduce gain; contrast may be turned up slightly if desired. 
 Tech. J ., vol. 39, pp. 
 65.Trunk,G.V.:Detection ResultsforScanning RadarsEmploying Feedback Integration, IEEETrans., vol.AES-6,pp.522-527, July,1970. 66.Cantrell, B.H.,andG.V.Trunk: Angular Accuracy ofaScanning RadarEmploying aTwo-Pole Filter,IEEE Tra".~.,vol.AES-9,pp.649-653, September, 1973. 67.Trunk,G.rV.:Comparison ofTwoScanning RadarDetectors: TheMoving Window andtheFeed­ backIntegrator, IEEETrans.,vol.AES-7,pp.395-398, March,1971. 
 Automatic detection and tracking circuitry can aid in this form of discrimination  since it provides a method for obtaining the target track. The long-range capability of HF  over-the-horizon radar (Sec. 14.2) is also useful for this purpose since it can observe a large  portion of the target track and might even be capable of observing where the target track  originates (airport or seaport), which can be an important classification clue in some  applications. 
 ORDER WAVEGUIDE MODES  RATHER THAN MULTIPLE HORNS FOR INDEPENDENT CONTROL OF SUM 
 LIKE CENTRAL SPIKE WITH A CLEAR AREA AROUND IT -EASUREMENT IS THEN PERFORMED ON THE HIGH 
 (2). Second, as discussed in Section 4.2, a stretch in the middle of the test highway was still undergoing road surfacing from June 2014 to November 2014, and compaction of the soft soil layer in the middle section may have accelerated the subsidence phenomena in nearby stretches. (3). 
 (13.20), but considerable variability exists among the reported resi~\ts.'~'  Part of this is probably due to the difficulty in obtaining quantitative measurements and the  variability of rain with time and from one location to another. One form of Eq. (13.20) that has  been widely accepted is  where Z is in mm6/m3 and r is in mm/h. 
 Alternatively, from the time delay point of view, a  narrow pulse impressed at the input of the series-fed array of Fig. 8.14, requires a finite time to  THEELECTRONICALLY STEERED PHASED ARRAY ANTENNA INRADAR299 Thephasedifference between twoadjacent elements intheseriesfedarra)ofFig.8.14is cjJ=2rcfl/u=2rcl/A (8.16) wheref=frequency oftheelectromagnetic signal i=lengthoflineconnecting adjacent elements (generally greaterthanthedistance between elements) f'=-::velocity ofpropagation inthetransmission line ).=wavelength Forconvenience ofanalysis, thevelocity ofpropagation istakentobeequaltoc,thevelocity oflight.Thisisapplicable tocoaxiallinesorsimilarstructures whichpropagate theTEMmode. Ifthebeamistopointinadirection 00,thephasedifference between elements shouldbe 2rc(d/A)sin00,Inafrequency-scan arrayitisusuallynecessary toaddanintegr1!ln!Hl1.9.~,!:-~ 2rcradiansofrelativephasedifference. 
 A radial velocity difference of more  than 25 m/s over the length of a jet runway ( ≈3 km) is a serious concern. One principal problem concerning microbursts is their short lifetimes, which are  on the order of 15–20 minutes but the duration of peak intensity is only 1 or 2 min - utes. Field research143 has clearly demonstrated that a few minutes advance warning  using doppler radar can be achieved. 
 100 l?kJwf27k v, v, ,AK!i 3.6k\& 6AK5 0.003 0.001 0.001 DlM 10k‘c 40.001 c6.3v FIG.1218.—I-f amplifier for lightweight receiver (AN/APS-l O).. 466 THE RECEIVING SYSTEAf—RADAR RECEIVERS [SEC. 12.10 necessary forthereception ofthe0.5-psec pulses employed bythesystem, toallow fortolerances intheadjustment oftheAI’C unit and int,hemanu- facture ofthei-fstrip aswell asforaslight spread inthefrequencies of beacons. 
 Pulse-to-pulse amplitude fluctuations of the echo signal have no effect on tracking accur­ acy if the angular measurement is made on the basis of one pulse rather th.an many. There are  several methods by which angle-error information might be obtained with only a single pulse.  More than one antenna beam is used simultaneously in these methods, in contrast to the  conical-scan or lobe-switching tracker, which utilizes one antenna beam on a time-shared  basis. 
 The linear array generates a fan beam when the phase relationships are such that the  radiation is perpendicular to the array. When the radiartion is at some angle other than  broadside. the radiation pattern is a conical-shaped beam. 
 Asaturated amplifier iscompatible withfrequency andphase-modulated pulsecompression waveforms. Whenusedinanamplifier chain,theCFAisgenerally foundillonlytheoneortwo highest-power stages.Itisoftenpreceded byamedium-power traveling-wave tube.This combination takesadvantage ofthebestqualities ofbothtubetypes.TheTWTprovides high gain,andtheCFAallowshighpowertobeobtained withhighefficiency, goodphasestability, andlowvoltage.20 Thecharacteristics ofaCFAareillustrated bytheVarianSFD-257, aforward-wave tube usedinthefinalhigh-power amplifier stageofthetransmitter chainintheAN/MPS-36 C-band range-instrumentation tracking radar.lsTheSFD-257 operates overthefrequency range5.4to5.7GHzwithapeakpowerof1MW,0.001dutycycle,andanefficiency ofover50 percent.Thetubeisd-coperated inthattheRFpulseturnsthetubeonandacontrolelectrode turnsitofT.Inthisradarapplication thepulsewidthsare0.25,0.5,or1.0JiS,butthetubecan deliverapulseaswideas5J-lS.Acodedgroup,orburst,offive0.25JiSpulsesisalsoutilized.It. KADAK TRANSMITI.EHS 213  require5 50 kW ofdrive power arid operates with 30 kV anode voltage and 70 A of peak anode  currerit Liquid cooling is employed for both ttie anode and cathode. 
 Time domain  amplitude and phase distortion, termed modulation distortion  by Cook and Bernfeld,  can result from power supply ripple in high-power transmitter amplifiers.2 Weighting  FunctionPeak Time Sidelobe  Level (dB)3-dB Mainlobe  Width, t36-dB Mainlobe  Width, t3Filter Matching  Loss (dB) Uniform −13.2 0.886/ B 1.21/ B 0 Taylor (−40 dB, n = 6)−40 1.25/ B 1.73/ B 1.15 Hamming −43 1.30/ B 1.81/B 1.34TABLE   8. 2 Comparison of LFM Weighting Filters ch08.indd   8 12/20/07   12:49:53 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 However, thetotalvariation (dynamic range)ofthe received signalwithtargetposition isnotaspronounced withbistaticradaraswithmonostatic radar.Inbistaticradar.aseitherDrorDrdecreases. theotherincreases. Thusthebistaticradar docsnot"overdetect ..atshortrangesasdoesmonostatic radar. 
 The amplifier is a 1-2-4 configuration, and each of the four final stages delivers 110 W peak for 16-ms pulse widths at duty cycles up to 25 percent. Table 5.5 enumerates some of the salient measured performance FIG. 5.13 Block diagram of the PAVE PAWS transceiver module.Control T/R Logic BITE Logic Phase Shift Logic Txmt/RoT Port 4—Btt Phaa« ShIfUrAntenna Rlement BTTE Switch Low-Pwr LimiterBTTE SwitchHi-Pwr Umiter Low Noise Amplifier Transmit Chain: Loss Budget k RF Power Levels Receive Chain: Gain/Loss Budget & Noise Figure Levels . 
 Bates, C. N.: New Advances in Doppler Radar, Countermeasures, vol. 2, pp. 
 LOOK  
 The cost of the corr~pirter hiirdware and software of ii ni~iltifiinction radar system ciin 1~ a  significant fraction of the total system cost. Compilter system design ~niist be integral wit11 that  of the radar hardware itself. The development of the software can be an especially.~iemanding  task that cannot be considered minor. 
 Lab. Tech. Mem. 
 8.27. If a signal is inserted in port No. 1. 
 However, more realistic pulse representations show substantial improvement. The triangular and cosine representations have a rolloff of about 30 dB per decade; the smoother cosine- squared and gaussian representations roll off at 40 dB per decade.MAXIMUM IMPROVEMENT FACTOR (dB) . 76.70 EFFECT OF MULTIPLE SPECTRA An airborne search-radar system may be operated at an altitude so that the radar horizon is approximately at the maximum range of interest. 
 30, pp. 258–264, 2004. 36. 
 It is difficult to overcome the fragility problem with robust materials, but the band - width can be improved by cascading several sheets, as shown in Figure 14.26. This  creates what is known as a Jaumann absorber . The bandwidth rises with the number  of layers and can attain a respectable 140% for a four-sheet design, as suggested in  Figure 14.27. 
 In an RC  low-pass filter y = Tp/RC, where Tp is the pulse repetition period and RC is the filter time  constant.  In order to find the signal-topnoise ratio for a given probability of detection and probabi-  lity of false alarm, an analysis similar to that used to obtain Figs. 2.7 and 2.8 should he  (2.32) (2.33)32INTRODUCTION TORADAR SYSTEMS andprobability offalsealarm,orfalse-alarm number, sincethereisnostandardiLation of definitions. 
 NOISE RATIO LOSS COMPARED TO THAT OF MATCHED FILTER PROCESSING ALONE  n°ÓÊ *1 - 
 The output of the first threshold is sampled by the quantizer at least once per range-resolution  cell. A standard pulse is generated if the video waveform exceeds the first threshold, and  nothing if it does not. These are designated by 1 or 0 respectively. 
 591 605, May. 1973.  29. 
 FIG. 17.14 Principle of two-PRF ranging. In a surveillance radar a number of receiver gates are used to detect targets that may appear at any range within the interpulse period. 
 as a result of using both feeds for  transmission. The phase center on transmit is half-way between the two feeds, and the phast:  center on receive alternates from one feed to the other.) As the antenna pointing-direction  changes from the port to starboard side of the vehicle, the sign of the difference signal must be  reversed to keep the displaced beams in the proper orientation.  The dashed curves of Fig. 
 OUS LEVELS IS NONTRIVIAL  AND THE RECEIVER DESIGNER TYPICALLY REQUIRES TABULATED DATA GENER 
 3.3 dominates as the antenna  approaches within a few beamwidths of the aircraft’s ground track. In this region  fV V dy y≈ ≈42 λθ θ λsin 22  (3.23) which yields a single-sided spectrum that is significantly narrower than the spectrum  abeam. For moderate platform speeds and lower-frequency (UHF) radars, this effect  is negligible, and compensation is not required. 
 TIONS TRACK UPDATES  #UED 3EARCH  CALIBRATIONS  ETC  WITH !UTONOMOUS 3EARCH 4HE RADAR COMPUTERS RESOURCE MANAGER MUST ENSURE THAT THE MAXIMUM FRAME TIME IS NOT EXCEEDED WITH THE INCLUSION OF THESE OTHER FUNCTIONS DURING A SEARCH FRAME &OR AIRBORNE PULSE DOPPLER RADARS  !UTONOMOUS 3EARCH CAN HAVE TWO SUBMODES  &ORWARD 
 P. Mikulich, R. Dolusic, C. 
 RESPONSE FEEDFORWARD CANCELERS COMPARED WITH THREE 
 COURSE OUTCOMES   1. Demonstrate an understanding of the factors affecting the radar performance using Radar  Range Equation.   2. 
 It is capable of high  average and peak power. high gain, good efficiency, stable operation, low interpulse noise, and  it can operate with tlie modulated wavefornis required of sophisticated pulse-compression  systems.  I)escription. 
 SPACE PROPAGATION LOSS AND PROPAGATION LOSS WITHIN THE %ARTHS ENVIRONMENT AS COMPUTED BY !0- 4HUS  !2%03 CONTAINS A FAIRLY SIMPLISTIC PULSED 
 Another advantage has to do with dynamic range. In an analog beamforming sys - tem, there is only one receiver and ADC, and the dynamic range performance is lim - ited to the capability of a single channel. In a digital beamforming system, there are  multiple receivers and ADCs, and the number of ADCs that are combined determines  the system dynamic range. 
 Range tracking might be accomplished by an operator who watches an A-scope or  J-scope presentation and manually positions a handwheel in order to maintain a marker over  the desired target pip. The setting of the hand wheel is a measure of the target range and may be  converted to a voltage that is supplied to a data processor.  As target speeds increase, it is increasingly difficult for an operator to perform at the  necessary levels of efficiency over a sustained period of time, and automatic tracking becomes  a necessity. 
 If the Sequential Observer allows a savings in average power of from 8 to 10 dB when  implemented for a single-range cell, the power advantage decreases to 3 to 4 dB for 200-range  cells and can even be as little as 1 dB.40 In addition, the Sequential Observer requires some-  thing more flexible than the usual rotating-antenna radar. Because of the variable dwell time  the anteona beam-positioning system must usually be a phased-array antenna and the data  processing must be digital. Thus if full benefit is to be had from the Sequential Observer in  radar, only one or a few independent decisions per beam position should be made, It might be  employed when only a single " guard-band" is desired for detecting targets within a selected  range interval, a not too usual application. 
 358 INTRODUCTION TO RADAR SYSTEMS  The storage tube uses two electron beams generated by separate electron guns. One is a  writing beam. The other is a .. 
 Inthisedition,onechaptercoverstheconventional radarantenna (Chap.7)anda separate chaptercoversthephased-array antenna (Chap.8).Devoting asinglechaptertothe arrayantenna ismorearellection ofinterestratherthanrecognition ofextensive application. Thechapteronradarclutter(Chap.13)hasbeenreorganized toincludemethods forthe detection oftargetsinthepresence ofclutter.Generally, thedesigntechniques necessary for thedetection oftargetsinaclutter'background areconsiderably different from'those necessary fordetection inanoisebackground. Othersubjects thatareneworwhichhaveseensignificant changes inthecurrenteditionincludelow-angle tracking, "on-axis" tracking, solid-state RF sources, themirror-scan antenna, antenna stabilization, computer controlofphasedarrays, )Olid-state duplexers, CFAR,pulsecompression, targetclassification, synthetic-aperture radar, over-the-horizon radar,air-surveillance radar,height-finder and3Dradar,andECCM.The bistaticradarandmillimeter-wave radararealsoincluded eventhoughtheirapplications have. 
 I RE, vol. 36, pp. 466 473,  April, 1948. 
 Cjersten: AN/TPS-59 Overview, IEEE 1975 Itrternational Radur Cot!/i~re~nc.r.  Arlington, Va.. Apr. 
 CENT  THE DOPPLER FREQUENCY IN HERTZ IS APPROXIMATELY EQUAL TO V R KT  DIVIDED BY K M  4HE DOPPLER FREQUENCY SHIFT IS WIDELY USED TO SEPARATE MOVING TARGETS FROM   STATIONARY CLUTTER  AS DISCUSSED IN #HAPTERS  THROUGH  3UCH RADARS ARE KNOWN AS -4) MOVING TARGET INDICATION   !-4) AIRBORNE -4)   AND PULSE DOPPLER !LL MODERN AIR 
 It is furthermore assumed that bias errors have been removed.  It will be shown that the rms error SM of a radar measurement M can be expressed as  where E is the received signal energy, No. is the noise power per unit bandwidth, and k is a  constant whose value is of the order of unity. 
 Inc.•Princeton. N.J.•1955,pp.440-442. 32.Delano. 
 Noviello, C.; Fornaro, G.; Mertorella, M. Focused SAR image formation of moving targets based on Doppler parameter estimation. IEEE T rans. 
 EXCITER COMMON PHASE NOISE  RECEIVER AND EXCITER UNCOMMON PHASE NOISE  AND THE TRANSMITTER PHASE NOISE )F THE SPECTRA OF THESE COMPONENTS ARE AVAILABLE  EITHER THROUGH MEASUREMENTS OR THROUGH PREDICTIONS BASED ON SIMILAR DEVICES  THE CONVOLU 
 2011 ,33, 125–130. 2. Zhang, J.; Peng, J.; Zheng, J.; Yao, Y. 
 GUITIES 2ANGE AMBIGUITIES ARE NOT AS EASY TO IDENTIFY AS AZIMUTH AMBIGUITIES  BECAUSE THEY ARISE FROM RANGES OUTSIDE OF THE NOMINAL SWATH  HENCE NOT OTHERWISE IMAGED 2ANGE AMBIGUITIES BY DEFINITION ARISE FROM RANGES THAT ARE DIFFERENT FROM THOSE FOR WHICH THE  PROCESSOR IS SET  SO THAT RANGE 
 6.9 SOLID-STA TE TRANSMITTERS  There have been two general classes of solid-state devices considered as _potential sources of  microwave power for radar applications. One is the transistor amplifier and the other is the  single-port microwave diode that can o·perate as either an oscillator or as a negative-resistance  amplifier. The silicon bipolar transistor has, in the past, been of interest at the lower micro­ wave frequencies (L band or below)~ and the diodes have been of interest at the higher micro­ wave frequencies. 
 W. Pidgeon60  © American Geophysical Union 1968 ) ch15.indd   21 12/15/07   6:17:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
  AND !. &03 
 Good circuits suppress fixed targets to 1% (voltage).     Figure 8.10  Block diagram of MTI Rada r.  Trigger Generato r Modulato rCarrier Oscillato rDelay line Attenuatio nAmplifier Det. 
 CESSING USED TO PERFORM THE BASEBAND CONVERSION AS DESCRIBED IN 3ECTIONS  AND  )1 DEMODULATORS ARE STILL USED  THOUGH THEIR USE IS INCREASINGLY LIMITED TO WIDER BAND 
 May.1976. 102.Trebits,R.N.,R.D.Hayes,andL.C.Bomar:mm-wave Reflectivity ofLandandSea,MicrowUL't' J.. vol.21,pp.49-53,83,August, 1978. 
 INDUCTANCE PACKAGE HAS AN OVERALL FOOTPRINT OF  r  0HOTOGRAPH COURTESY OF 2AYTHEON #OMPANY  . ££°£Ó  2!$!2 (!.$"//+  4HE SILICON ,$-/3 &%4 &IGURE  D  IS PROCESSED ON P  MATERIAL WITH A LIGHTLY  DOPED P 
 DELAY CHANGES ARE REQUIRED IN EACH AMPLIFIER CHAIN TO ACCOMPLISH AZIMUTHAL STEERING ! BROAD 
 ART GRAVIMETRIC VARIATIONS EXPRESSED AT THE OCEANS SURFACE  AND CONSEQUENTLY  OCEANIC BATHYMETRY   4HE PRINCIPAL OBJECTIVE OF A GEODETIC SATELLITE RADAR ALTIMETER  IS TO MEASURE THE ALONG 
 W.: Some Technical Aspects of Microwave Radiation Hazards, Proc. IRE, vol. 49,  pp. 
 O. Hall: A High Resolution Radar Combat-Surveillance System, IRE Trans., vol. MIL-5, pp. 
 M CROSS 
 10. 15. F. 
 F. Black well. and T. 
 BAND 3!2  ! PRIME MOTIVATION FOR THE #ANADIAN 2ADARSAT 3!2 WAS MONITOR 
 If m of these expected n pulses exceed a predetermined value (threshold),  a target may be declared to be present. The use of a criterion that requires m out of n echo  pulses to be present is a form of integration. It is less efficient than ideal postdetection  integration, but it has the advantage of simplicity. 
 The proposed scintillation simulator can also be applied to predict the scintillation effect for other multi-mode SAR systems such as terrain observation by progressive scans (TOPS) and ScanSAR. Finally, a group of simulations are carried out to validate the theoretical analysis. Keywords: ionosphere; P-band; reverse back-projection (ReBP); synthetic aperture radar (SAR); sliding spotlight; scintillation 1. 
 The use of subarrays usually simplifies the problem of the beam-steering computer.  Instead of requiring a command for each of the elements of the array, the subarray steering  requires only p + q phase shifter commands per pointing angle, where p is the number of  elements in the subarray and q is the number of subarrays in the array. However, with q  identical subarrays of p elements each, the tolerance on the individual phase shifters must  usually be better than with a similar conventional array of pq elements since with subarrays  ' the errors across the entire aperture are no longer independent. 
 These methods are  more typically applied for precision analysis of microwave devices or electrically  “smaller” antennas, e.g., radiators and feeds, that are no more than a few wavelengths  in size. In recent years, hybrid methods incorporating PO or GO/GTD along with  MOM, FEM, or FDTD have been developed. These methods enable enhanced reflec - tor feed modeling, i.e., integrated with reflector analysis, and rigorous modeling of  electrically small scatterers, e.g., small subreflectors or feed support struts. 
 l I. 1969.  27. 
 Largeclutterenergyisdesired sincethe"clutter" isthetarget. Tiledetectionofterrainfeatllres suchashillsandmountains aheadofanaircrafttowarnof approaching highground(terrainol'oidonce) ortoallowtheaircrafttorollowthecontour oftheland(terrain/allowing). Marring. 
 LINE PHASE BIT    B  HYBRID 
 If limiting is employed, however, the  correct decision remains firm. In a complex environment where there are many radar tracks and DF signal sources,  it is quite possible that many DF signals will be assigned the category that the DF  signal probably goes with some radar track. To remove many of these ambiguities,  multisite DF operation can be considered. 
 BEAM WITH THE GROUND .OTE THAT THE CLUTTER 
 Using a combination of Bayes and Neyman-Pearson  procedures and assuming that the DF detection errors are usually independent and  gaussian-distributed with zero mean and constant variance s2 but with occasional out - liers (i.e., large errors not described by the gaussian density), Trunk and Wilson argued  that the decision should be based on the probability  Pj = probability ( Z ≥ dj) (7.44) where Z has a chi-square density with nj degrees of freedom and dj is given by  d t t jj in e i j ij = − = =∑ 12 24 1 min{ ,[ ( ) ( )]/ } ,. ., θ θ σ m m  (7.45) where nj is the number of DF detections overlapping the time interval for which the  jth radar track exists; qe(ti) is the DF detection at time ti; qj(ti) is the predicted azimuth  of radar track j for time ti; and the factor 4 limits the square error to 4 s2 to account for  DF outliers. By using the two largest Pjs, designated Pmax and Pnext, and thresholds  TL, TH, TM, and R, the following decisions and decision rules were generated: 1. 
 Antennas Propag .,  vol. AP-32, no. 34, pp. 
 79. J. O. 
 Figure 12.13  Sea target scenario and threshold, processed with MAM IS-CFAR (A = 16, L=  8, α = 1, β = 45).   As a first step, the quality of a CFAR threshold is judged considering the above sc enario with  targets and clutter interference (sea clutter, rain areas). For this, we co nsider the sea target sce- nario and the CFAR th resholds documented in Figures 12.8 -12.13. 
 Among the more significant challenges facing researchers  today is the need to make global measurements of precipitation. Understanding global  climate requires that quantitative measurements of precipitation be made throughout  the world, particularly in the tropics and over the oceans. Satellite observations appear FIGURE   19. 
 Kaisel, S. F.: Microwave Tube Technology Review, Microwave J., vol. 20, pp. 
 The smaller sector shown as Task 6, extending to a range of 400 km, is representative  of the coverage of an HF surface wave radar, as used for protecting the approaches to  a port, for example. This example is typical of the scheduling and resource allocation problem that is  central to HF skywave radar operations. Compromises are often unavoidable. 
 Sincethecrosssectionofobjects withintheRayleigh regionvariesasA.-4,rainandcloudsareessentially invisible toradars whichoperateatrelatively longwavelengths (lowfrequencies). Theusualradartargetsare muchlargerthanraindrops orcloudparticles, andlowering theradarfrequency tothepoint whererainorcloudechoesarenegligibly smallwillnotseriously reducethecrosssectionof thelargerdesiredtargets.Ontheotherhand,ifitweredesiredtoactuallyobserve, ratherthan eliminate, raindrop echoes,asinameteorological orweather-observing radar,thehigher radarfrequencies wouldbepreferred. Attheotherextreme fromtheRayleigh regionistheopticalregion,wherethedimensions ofthespherearelargecompared withthewavelength (2na/A. 
 W. J. Caputi, “A technique for the time-transformation of signals and its application to directional  systems,” The Radio and Electronic Engineer , pp. 
 DELAY CANCELER WILL PERFECTLY CANCEL  6T    C   AT   BT   ! STAGGER SYSTEM WITH  TWO PULSE INTERVALS SAMPLES THE LINEAR WAVEFORM AT UNEQUAL INTERVALS  AND THEREFORE  &)'52%   %FFECT OF FEEDBACK ON THE VELOCITY RESPONSE CURVE DUAL CANCELER   PULSE 
 In this chapter, the echoes from land, sea, and weather will be considered only for their  harmful effects; that is, as clutter to be avoided or eliminated. The characteristics of clutter will  be described as well as the various methods for reducing their harmful effects when they  interfere with the detection of desired targets.  Echoes from the land or the sea are known as surface clutter, and echoes from rain or  other atmospheric phenomena are known as volume clutter. 
 T. Ulaby and W. H. 
 Multipath angle errors result from reflections of the target echo  from objects or surfaces causing echo pulses to arrive by other than the direct  path to the radar beam in addition to the  direct path. These errors are sometimes  called low-angle tracking errors  when  applied to tracking of targets at small  elevation angles over the Earth or  ocean surface.46–50 Multipath errors are  typically a special dual-source case of  angle noise resulting from the geometry  as described in Figure 9.26, where the  target and its image reflected from a  FIGURE   9.26  Geometry of the radar multipath  tracking condition, where the reflection from a  surface appears to the radar as an image below  the surface ch09.indd   37 12/15/07   6:07:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 One half ofthe remaining double diode isused asanr-fdetector toprovide arelative power indica- tion onapanel meter which isalso used, bymeans ofarotary selector switch, tomeasure thegrid currents oftheseveral doublers. This diode isalso connected toatest point toallow ascope tobeused when over-all alignment and bandwidth measurements are being made. Because of thestability ofthis transmitter, itwas found unnecessary touseabidirec- tional coupler with it. 
 Such asituation arises inthe presence ofvery severe clutter, where pulse systems, even with MTI equipment, may failtogive any information. Certain doppler systems, onthe other hand, will provide useful and even adequate information. Third, the price ofrapid transmission ofdata isacertain degree of apparatus complexity. 
 ThedigitalMTIprocessor depicted inFig.4.21isthatofasingle-delay­ linecanceler. Digitalprocessors arelikelytoemploymorecomplex filteringschemes, butthe simplecanceler isshownhereforconvenience. Almostanytypeofdigitalstoragedevicecanhe used.Ashiftregister isthedirectdigitalanalogy ofadelayline,butotherdigitalcomputer memories canalsobeusedeffectively. 
 ch11.indd   31 12/17/07   2:25:41 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 
 155.  66. Lindner, J.: Binary Sequences Up to Length 40 with Best Possible Autocorrelation Function, Elec-  tronics Letters, vol. 
 The roHowing references (2 to 8) appear in IRE Trans., vol. IT-6, no. 3, June, 1960, special issue on  Matched Filters:  2. 
 Mudukutore, V . Chandrasekar, and R.J. Keeler, “Pulse compression for weather radars,”  IEEE Trans. 
 It requires the specification of a  minimum level, typically the noise floor, the maximum level that can be handled  with some allowable deviation from the ideal response, and the type of signal to  be handled. These parameters are defined through a variety of characteristics as  described below. Modern radars systems increasingly rely solely on linear receiver channels fol - lowed by digital signal processing, providing both increased flexibility and near  ideal signal-detection characteristics. 
 Since thebandwidth ofthereceiver foral-psec pulse would beabout 2Me/see, frequency modulation ofthis magnitude will result inaserious loss ofreceived energy. When longer pulses and correspond- ingly narrower bandpass receivers areused, this problem becomes much more critical and may place very severe requirements ontheflatness of thecurrent pulse. Instabilities.—It has sofarbeen found impossible toconstruct mag- netrons that donot occasionally present tothe pulser either avery low impedance asaresult ofagasdischarge (sparking) within thetube, ora very high impedance due toafailure ofthemagnetron tooscillate inthe proper manner (mode-changing). 
 V 4HE FINAL STAGE IS TO PERFORM A FREQUENCY  SHIFT AND SAMPLE RATE REDUCTION BY DECIMATING THE SIGNAL BY SELECTING EVERY  $TH SAMPLE &)'52%  (ILBERT TRANSFORMER ARCHITECTURE          &)'52%  3PECTRA OF (ILBERT TRANSFORMER RECEIVER                    
 Moore, and A. K. Fung37) FIGURE   16. 
 Inorder toexclude moisture, theentire line, including thethree rotary joints and thefeed, ispressurized toabout 5lb/in. ZThe mount, weighing some 2200 lb,isinstalled onanelevator inthetrailer and somay beraised foruseorlowered into thetrailer forstowage. The AN/TPS-10.—A second antenna mount ofinterest isthat of AN/TPS-101 (Fig. 
 UP SCHEME IS RECOMMENDED TO PREVENT DESIRED  TARGETS FROM COMPETING WITH MAIN 
 However, since thedouble adjustment ofthetwo switches isnotalways made correctly, fixed-tuned, low-Q ATR switches are preferable. Figure 11.18 shows the 1B35 tube, designed forthe3-cm band, and itsmounting. One such tube will cover afrequency band of3percent, and pairs ofthese tubes will cover a band of6percent. 
 Remote Sens. Mag. 2013 ,1, 6–43. 
 Moraitis, “Probability of detecting a Swerling I target on two correlated  observations,” IEEE Transactions on Aerospace and Electronic Systems,  vol. AES-17, no. 5,  pp. 
 Eliminating 36 percent of the dopplers means limiting the system to a long-term average of 64 percent single-scan probability of detection. Feedback can be used to narrow the rejection notch without much degradation of/. If feedback is used to increase the improvement factor, the single-scan probability of detection becomes worse. 
 MATES FROM SATELLITE RADAR SCATTEROMETER DATA v  * OF 'EOPHYSICAL 2ESEARCH   VOL $    PP n    , " +UNZ AND $ ' ,ONG  h#ALIBRATING 3EA7INDS AND 1UIK3#!4 SCATTEROMETERS USING NATURAL  LAND TARGETS v )%%% 'EOSCIENCE AND 2EMOTE 3ENSING ,ETTERS  VOL   PP n    2 + -OORE  h3IMULTANEOUS ACTIVE AND PASSIVE MICROWAVE RESPONSE OF THE %ARTH 4HE 3KYLAB  2!$3#!4 EXPERIMENT v IN  0ROCEEDINGS  OF  THE  TH  )NTERNATIONAL  3YMPOSIUM  ON  2EMOTE  3ENSING  !NN !RBOR  -ICHIGAN    PP n  - 3HIMADA AND ! &REEMAN  h! TECHNIQUE FOR MEASUREMENT OF SPACEBORNE 3!2 ANTENNA  PATTERNS USING DISTRIBUTED TARGETS v  )%%% 4RANSACTIONS ON 'EOSCIENCE AND 2EMOTE 3ENSING    VOL   PP n    7 , 'RANTHAM  % - "RACALENTE  , 7 *ONES  AND * 7 *OHNSON  h4HE 3EASAT 
 Phased array theory was studied intensively in the 1960s. Technology advanced  and led to a series of operational systems in the 1980s; many publications became  available.4–15 In terms of performance improvement, ultralow sidelobes (less than  −40 dB) were demonstrated first in the 1970s by Westinghouse Electric Corporation’s  AWACS (Airborne Warning and Control System) and brought about tight tolerances in  construction and phase settings. The advent of more and better computer modeling and  sophisticated test equipment such as network analyzers has led to improved methods  of designing well-matched apertures. 
 Insects can be carried by the wind; therefore angels due to insects  might be expected to have the velocity of the wind. Insect echoes are more likely to be found a1  the lower altitudes, near dawn and twilight. The majority of insects are incapable of flight at  temperatures below 40°F (4.5°C) or above 90°F (32°C); consequently. 
 DOMAIN PULSE COMPRESSION PROCESSING IS PERFORMED  !32 
 Free-running oscillators forgenerating the trigger have been built tofirethetransmitter atasuitably constant rate. Because of thelarge thermal coefficient ofdelay inmercury, normal fluctuations in ambient temperature necessitate manual readjust ment ofsuch oscillators atintervals ranging from 10min to1hr. Since this amount ofattention cannot betolerated inmost applications, several methods have been devised for automatically maintaining time synchronism between the PRF and the supersonic delay. 
 Attenuation in the atmosphere and rain is very high, and per - formance in bad weather is quite limited. Receiver noise is determined by quantum  effects rather than thermal noise. For several reasons, laser radar has had only limited  application. 
    %QUATION  DESCRIBES THE FUNDAMENTAL RESPONSE OF A SCANNED ARRAY SYSTEM 4HE  ARRAY WILL HAVE ONLY ONE SINGLE MAJOR LOBE  AND GRATING 
 (UYGENS PRINCIPLE HAVE BEEN THOROUGHLY DEVELOPED  n 4HE +IRCHHOFF APPROXI 
 FREQUENCY  )&  AMPLIFIER AND A LIMITER AHEAD OF THE NARROW 
 The gain of an MPM might be nominally 50 dB and is  divided between the solid-state driver and the TWT power booster in the ratios from  20/30 to 30/20. The MPM seems best suited for the higher microwave frequencies,  perhaps from 2 to 40 GHz. A serious constraint of the MPM for radar applications is that the helix TWT limits  its use to CW or high duty cycle transmissions (preferably greater than 50%). 
 ITY OF CHANGING FREQUENCY OVER A VERY WIDE BANDWIDTH CAN  WITH ADVANTAGE  ADAPT ITS TRANSMISSION TO TAKE INTO ACCOUNT FREQUENCY 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 7 .24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 FIGURE 7.25  Structure of automatic tracking process ch07.indd   24 12/17/07   2:13:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Soofi, and S. M. Purduski114 © IEEE 1980TABLE   16. 
 Included in this class are high-end servers and embedded processor architectures.  Servers are typically homogeneous processors, where all of the processing nodes  are identical and are connected by a very high-performance data bus architecture.  Embedded processor architectures are typically composed of single-board computers  (blades) that contain multiple general-purpose processors and plug into a standard  backplane architecture, such as VME. 
 3.12a). On one portion of the frequency-modulation  cycle. tlie beat frequerlcy (Fig. 
 ROOT SENSE 4HE APPROACH TO PREVENTING FALSELY COMPOSED TRACKS FROM DIFFERENT OBJECTS IN A  CLUTTER REGION   '  IS TO REQUIRE ENOUGH DETECTIONS IN A TIGHT ENOUGH PATTERN TO MAKE  %;. &4=  THE EXPECTED NUMBER OF FALSE TRACKS  SMALL 7HEN THERE IS AN AVERAGE OF  .#  DETECTIONS IN A $ 
 The components in each channel need only have a bandwidth 1/N times the total  processing bandwidth. Still another advantage of such systems is that a strong CW interfer-  EXTRACTION OFINFORMATION ANDWAVEFORM DESIGN431 Adifferent phase-coded sequence canbeassigned toeachradarsothatanumberof radarscansharethesamespectrum. Inamilitary radar,thecodingcanbechanged tohelp counterrepeaterjammers thatattempttosimulate thewaveform. 
 Curves 3, 4, and 5 are similar to curve 2, except  that they apply to a free-space signal of 110, 55, and 27.5 nautical miles, respectively. Curve 6  .... .... 
 T able 1. Resnet models Layer Name Output Size 18-Layer 34-Layer 50-Layer 101-Layer 152-Layer conv1 112×112 7×7, 64, stride 2 conv2_x 56×563×3 max pool, stride 2 /bracketleftbigg3×3, 64 3×3, 64/bracketrightbigg ×2/bracketleftbigg3×3, 64 3×3, 64/bracketrightbigg ×3⎡ ⎣1×1, 64 3×3, 64 1×1, 256⎤ ⎦×3⎡ ⎣1×1, 64 3×3, 64 1×1, 256⎤ ⎦×3⎡ ⎣1×1, 64 3×3, 64 1×1, 256⎤ ⎦×3 conv3_x 28×28/bracketleftbigg3×3, 128 3×3, 128/bracketrightbigg ×2/bracketleftbigg3×3, 128 3×3, 128/bracketrightbigg ×4⎡ ⎣1×1, 128 3×3, 128 1×1, 512⎤ ⎦×4⎡ ⎣1×1, 128 3×3, 128 1×1, 512⎤ ⎦×4⎡ ⎣1×1, 128 3×3, 128 1×1, 512⎤ ⎦×8 conv4_x 14×14/bracketleftbigg3×3, 256 3×3, 256/bracketrightbigg ×2/bracketleftbigg3×3, 256 3×3, 256/bracketrightbigg ×6⎡ ⎣1×1, 256 3×3, 256 1×1, 1024⎤ ⎦×6⎡ ⎣1×1, 256 3×3, 256 1×1, 1024⎤ ⎦×23⎡ ⎣1×1, 256 3×3, 256 1×1, 1024⎤ ⎦×36 conv5_x 7×7/bracketleftbigg3×3, 512 3×3, 512/bracketrightbigg ×2/bracketleftbigg3×3, 512 3×3, 512/bracketrightbigg ×3⎡ ⎣1×1, 512 3×3, 512 1×1, 2048⎤ ⎦×3⎡ ⎣1×1, 512 3×3, 512 1×1, 2048⎤ ⎦×3⎡ ⎣1×1, 512 3×3, 512 1×1, 2048⎤ ⎦×3 1×1 average pool, 1000-d fc, softmax FLOPs 1.8×1093.6×1093.8×1097.6×10911.3×109 • Other popular models In this paper, we also used some popular models to do transfer learning, such as Alexnet, Vgg-16 net, etc. These models are shown in Figure 3. 
 Pulse compression radar . This is a radar that uses a long pulse with internal modu - lation (usually frequency or phase modulation) to obtain the energy of a long pulse  with the resolution of a short pulse. Continuous wave (CW) radar . 
 10, pp. 165-166, May 16, 1974.  82. 
 The  parallel-line configuration has also been used when phase shifts greater than 2n radians are  needed, as in broadband devices which require true time delays rather than phase shift which is  limited to 2rc radians. .,  The cascaded digitally switched phase shifter (Fig. 8.6) has seen more application than the  parallel-line configuration. 
 The model for these angles isPOLARIZATION: VV ANGLE OF INCIDENCE (degrees) POLARIZATION: HH . <r°dB(/»0) = Me) + Me)/ e = o°, 10° (12.24/?) The frequency responses below 6 GHz differed for the two years; so the models have separate values of the constants for 1975 and 1976. The year 1976 was very dry in Kansas; so the 1975 values are probably more representative, but both are given here. 
 Nature for July 13, 1946, gave a detailed account of  scientific research into the peculiar mechanism which  enables the bat to transmit two high-pitched supersonic  notes simultaneously. One is a note of a frequency of  ' somewhere around 7000 cycles a second. This is on the  upper limit of the average human ear’s detection, though  some people with auditory systems capable of appre-  ciating very high frequencies can detect the shrill, con-  tinuous sound. 
 and F. C. Macdonald: Elevated Duct Propagation in the Tradewinds, I RE Trans.,  vol. 
 SPACE-BASED REMOTE SENSING RADARS  18.596x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 18.6 RADAR SOUNDERS In its most general form, a radar sounder is a device whose transmissions are designed  to penetrate the volume of a target medium, from which the waveform of the resulting  backscatter indicates variations in dielectric contrasts as a function of depth.† As a  sounder passes over an illuminated region, the sequence of ranging waveforms gener - ates a profile, which is a two-dimensional reflectivity cross section of the surveyed  volume. Penetration depth in general increases with wavelength and also with radiated  power. On the other hand, reflectivity depends on the dielectric contrasts between  internal layers; a material’s dielectric constant is also a function of wavelength. 
 (13.9)RADAR CLUTIER 473 widthrillEq.(l.lX)isthatofthecompresscJ'pulsc.pfthe statistics ofthedullerechoesare similartothestatistics ofreceiver noise,thenthesignal-to-clutter ratioinEq.(13.8)canbe selected similartothatforsignal-to-noise ratioasdescribed inChap.2.(Itwillbeseenin Sec.13.3thatadecrease inpulsewidthcanchangethenatureoftheclutterstatistics insOll1e casesandmightnegatethebenefits ofthegreatersignal-to-clutter ratioobtained withthe shortpulse.)Theimprovement inrangeduetotheintegration of/Ipulsesisnotindicated in thisequation. Therecanbeaconsiderahle difference intheintegration improvement when clutter-limited fromwhennoise-limited. Clutter echoes, unlikereceiver noise,mightbecor­ relatedpulsetopulse.especially iftheclutterisstationary relativetotheradar.Receiver noise isusuallydecorrelated inatimeequaltol/B,whereB=receiver (IF)bandwidth. 
 Theindividualtoroids areusuallyseparated bythin diet~ctric spacers toavoidmagnetic interaction (Fig.8:IOh).Thedrivewireisoriented forminimum RF coupling. Itisalsoimportant tohavepropermechanical contact hetween thetoroidandthe waveguide wallsinceanairgapcangiverisetothegeneration ofhigher-order modesthatcan resultinrelatively largenarrow-frequency-band, insertion-loss spikes.('urdul attention musl bepaidtoeliminating thesegapswithout excessive mechanical pressure Ihatcouldcause magnetostriction whichchanges themagnetic properties ofthematerial, especially ifgarnets areused.Thistypeoflatching phaseshifterisalsocalleda/will-sla" /owit/all'hasL' shifiersince themajoractionisduetothetwovertical branches ofthetoroids. Thefunction ofthe horizontal branches istocomplete themagnetic circuit. 
 CLUTTER MOTION )N SUMMARY  THE NOISE 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 1.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 Reduced Effectiveness of Hostile Countermeasures. 
 [ CrossRef ] 21. Cumming, I.G.; Wong, F.H. Digital processing of synthetic aperture radar data: Algorithms and implementation. 
 The doppler spectrum of the echo has sharp variations that require  careful processing to preserve. The receiver and processor must be able to handle  both the high-level signal due to this large RCS and those much smaller signals due  to targets, especially when the latter are adjacent to the strongest clutter components.  An HF radar must be designed to accommodate such clutter levels; even though, they  will not exist all the time, or at any one time, over all areas, especially at the lower  operating frequencies. 
 NOISE AMPLI 
 E,    4HIS HAS SOME BASIS IN CONTOUR 
 Other parts ofthe r-fhead can bemade smaller and more compact ifpressurized conditions areassumed. Itis but aslight extension toconsider that ther-fhead should gointo asingle pressurized container, with thepressure common tother-fline outtothe antenna. Such aplan solves two other problems: (1)theworking parts ofthe r-fhead are protected against the most severe conditions of moisture, salt spray, and dust, not only inuse, but also during shipment and storage; and (2)theshielding problem isgreatly simplified, both for keeping external disturbances outofthedelicate parts ofthereceiver, and. 
 I b IPeakquantization 0e=-in2 Thisapplieswhenthemainbeampointsclosetobroadside andtherearemanyradiating elements withinthequantized phaseperiod.Theposition ofthequantization lobeinthiscase IS (K33) (8.34) (8.35)where00=angletowhichmainbeamissteered.Equation (8.32)isanoptimistic estimate for thepeaklobe.Thegreatestphasequantization lobeissaidtooccurwhentheelementspacing isexactlyone-half thephasequantization periodoranexactoddmultiple thereqf. Hl.115With anelement spacingofone-half wavelength, thequantization lobewillappearatsin01~ sin00-I,withavalueof Pk..Ibn:2Icos()IeaquantIzatIOn 0e~-------- -4 228cos00 Thepeaksidelobes duetothephasequantization canbesignificant, andattempts should bemadetoreducethemiftheirpresence isobjectionable. Onemethodforreducing thepeak lobeistorandomize thephasequantization. 
 J.: The Air Height Surveillance Radar and Use of Its Height Data in a Semi-Automatic Air Traffic Control System, IRE Int. Conv. Rec., vol. 
 0EDESTAL 7EIGHTING  &IGURE A PLOTS THE  TAPER COEFFICIENT  & AND PEDESTAL HEIGHT  ( VERSUS THE PEAK TIME SIDELOBE LEVEL FOR  COSINE 
 2T T#I J     WHERE TI IS THE TRANSMISSION TIME OF THE  ITH PULSE &OR EXAMPLE  FOR A GAUSSIAN 
 TAMINATES THE ESTIMATION PROCESS FOR THE OTHER  4HIS PROBLEM IS MOST ACCENTUATED  WHEN THE CLUTTER 
 From Eq. (8.3), E0(0) = E0(1t -0). Therefore an antenna of isotropic elements has a  similar pattern in the rear of the antenna as in the front. 
 Radar System Engineering  Chapter 14 – Bibliography  168     − E. Heidrich; W. Wiesbeck, "Features of advanced polarimetric RCS -antenna mea s- urements," in Proc of the IEEE AP -S Int. 
 TION  AND FREQUENCY TO BE SPECIFIED 4HE KEY POINTS TO BE DRAWN FROM THIS EXAMPLE ARE I  THE APPARENT ADVANTAGE TO BE GAINED BY OPERATING AT LOW FREQUENCIES WHERE PROPAGA 
 RANGE SURVEILLANCE BECAUSE THE USUAL  RADAR EQUATION DOES NOT INCLUDE ALL THE PERTINENT FACTORS )N THE JAMMING CASE  ONE SHOULD TAKE ACCOUNT THAT THE  JAMMING ANTENNA ON AN AIRCRAFT HAS A LOWER GAIN AT LOWER FREQUENCIES SO THE JAMMING POWER DENSITY MIGHT BE LESS AT THE LOWER FREQUENCIES !LSO  WHEN MULTIPATH IS IMPORTANT  BY SELECTING THE RADAR FREQUENCY PROPERLY  ONE MIGHT REDUCE THE JAMMING POWER RECEIVED BY BEING IN A NULL OF THE JAMMER TRANSMITTING ANTENNA #HAFF MIGHT NOT BE AS EASY TO DEPLOY AT THE LOWER FREQUENCIES  )N CONCLUSION  THE LOWER RADAR FREQUENCIES MIGHT NOT BE AS VULNERABLE AS  ONE MIGHT THINK BY EXAMINING THE TRADITIONAL RADAR EQUATION. Ó{°{ä  2!$!2 (!.$"//+  !NOTHER CLASS OF %##- TECHNIQUES IS AIMED TO CONTRAST THE DECEPTIVE %#-  $ECEPTION JAMMERS HAVE A NUMBER OF SPECIFIC CHARACTERISTICS THAT CAN BE USED BY  RADARS TO IDENTIFY THEIR PRESENCE 4HE MOST PROMINENT IS THAT FALSE 
 Surv. 2017 ,41, 157–162. 47. 
 Since bistatic  clutter exhibits nonstationary space-time characteristics, bistatic STAP methods are  not simple applications of monostatic approaches, but a new class of algorithms.  Specifically, they apply a data-dependent weighting to voltages collected over mul - tiple receive antenna channels and pulses. This weighting dynamically tailors a filter  response in angle and bistatic doppler to suppress ground clutter reflections. 
 The detection decision  is made at the output of the receiver, so a target  is declared to be present when the receiver output exceeds a predetermined threshold.  If the threshold is set too low, the receiver noise can cause excessive false alarms. If  the threshold is set too high, detections of some targets might be missed that would  otherwise have been detected. 
 It is difficult to design a  repeater jammer that wil.l play back an exact reproduction of the radar signal. The radar echo  from a target can be considered as being linear, but the signal from a repeater is generally not  linearly related to that which was transmitted by t.he radar. Thus one strategy fcir defeating  repeater jamming is to utilize radar transmissions with a form of identification difficult to  mimic by the "nonlinear" repeater. 
 ABILITY MAY BE PROVIDED -ANY EARLY MODELS HAD THEIR GENESIS IN THE LARGE DATABASE OF RECORDED IONOSPHERIC SOUNDINGS MADE DURING THE )NTERNATIONAL 'EOPHYSICAL 9EAR OF n AND THE )NTERNATIONAL 9EAR OF THE 1UIET 3UN OF n 4HESE MODELS  . Óä°Óä  2!$!2 (!.$"//+  WHICH FOCUSED ON THE SPATIAL DISTRIBUTION OF ELECTRON DENSITY  WERE USED EXTENSIVELY  IN EARLY (& RADAR PERFORMANCE ANALYSES AND INCLUDE )43! 
  HAD COMPLETED ITS TH YEAR  LOGGING MORE  THAN   ORBITS AND COLLECTING ENOUGH DATA TO MAP THE ENTIRE SURFACE OF THE %ARTH AN EQUIVALENT OF  TIMES 4HE #ANADIAN )CE 3ERVICE RELIES ON 2!$!23!4 
 The signal would goinashielded cable toanappropriate external jack. The other checks onthe operation ofthe r-fhead divide themselves into (1)minimum informa.t ioncontinuous yavailable toaremote opera- torand (2)tests tobeperformed with the cover removed. The average magnetron current isthe most important single item in monitoring aradar set. 
 By “resolution,” in keeping with  common usage, we mean the precision to which we can measure the location of a point  target and not necessarily the ability to resolve two point targets. (For a discussion of this  issue, see Wolfe and Zissis.23) How we do this will be discussed in more detail below. Since fine range resolution is typically achieved with a single pulse, the corre - sponding processing is often termed fast-time processing . 
 As the target moves relative to the radar, its aspect  changes and the lobed pattern of the target cross section results in a fluctuating received signal.  These amplitude Huctuations occur at a slow rate, compared with the much higher frequency  fluctuations of the engine modulations mentioned above. The larger the size of the target the  narrower will be the lobes and the greater will be the fluctuation frequency for a given angular  rate or change of aspect. 
 But, in general, it is the nletliod by  which angle tracking is accomplished that distinguishes what is normally considered a tracking  radar from any other radar. It is also necessary to distinguish bet ween a c:onli,~~~olr.s tr'ic'liir~~g  radar and a track-while-scan (TWS) radar. The former supplies continuous tracking data on a  particular target, while the track-while-scan supplies sampled data on one or more targets. 
 For each target the  necessary information to be presented might consist of perhaps ten alphanumeric characters  and a number of line segments.35 When the amount of data is large, writing time might  have to be taken from the radar time by blanking one out of every n sweeps or writing the  synthetic information during a random interruption of the sweep. It is also possible to utilize  a second electron gun in the CRT to minimize the amount of time taken from the radar to  insert the synthetic data. Another method for achieving the necessary time to display alpha-  numeric data is to store the video in a shift register and then read it out at a higher rate. 
 Although thebrightbandisrelatively thin, considerable attenuation canoccur'whenradarobservations aremadethrough itatlow elevations. Thebrightbandisduetochanges insnowfallingthrough thefreezing level."Atthe onsetofmeltingthesnowchanges fromflatorneedle-shaped particles whichscatterfeeblyto similarly shapedparticles which,owingtoawatercoating, scatterrelatively strongly. As meltingprogresses, theparticles losetheirextreme shapes,andtheirvelocityoffallincreases causing adecrease inthenumberofparticles perunitvolume andareduction inthe backscatter..", '...;\1I, Scattering fromclouds.Most.cloud'droplets donotexceed100~mindiameter (IJlm= 10-6m);consequently Rayleigh scattering maybeappliedatradarfrequencies forthepredic­ tionofcloudechoes.InRayleigh scattering, thebackscatter isproportional tothesixthpower. 
 OFF  AND BE RECEIVED MAINLY THROUGH THE ANTENNA BEAMPATTERN SIDELOBES 4HE JAMMING SIG 
  AND '%/3 
 Ronchi, L., and G. Toraldo di Francia: An Application of Parageometrical Optics to the Design ofa  Microwave Mirror, IRE Trans., vol. AP-6, pp. 
 ETER  RADARS WITH ABOUT  n BEAMWIDTH HAVE THE SPATIAL RESOLUTION TO DETECT MESOCY 
 These pulses areintegrated orotherwise converted toavoltage, which isapplied toacontrol electrode ofthelocal oscillator inthe proper sense topush the frequency toward the crossover ofthe discriminator curve. This makes adegenerative feedback loop, and thefrequency ofthe local oscillator isheld very near the crossover point onthe curve. Asshown inFig. 
 9.2). Figure 9.2does not explain the side lobes orthe beamwidth, but itdoes serve toemphasize the fact that thefeed isalways sodesigned astobedirective. Figure 9.3represents anautomatic record of the energy radiated atvarious angles from a well-designed feed, thedirectional power being displayed asafunction ofangle. 
  BY  
 28, no. 2, pp. 139–150,  March–April 1993. 
 This  is seen clearly in Figure 15.3 a and b, which compares the grazing-angle dependence  of X-band clutter data for wind speeds in the neighborhood of 15 kt obtained from  four sources: NRL 4FR28 (these are mean  results for upwind directions and include  the antenna corrections mentioned above), aircraft measurements by Masuko et al.31  (also in the upwind direction), and summaries of data taken from books on radar  systems by Skolnik2 and Nathanson.3 The discrepancies between the different data  sets can be accounted for, at least in part, as follows. The older data summaries were  based on published measurements from various sources in which there is no speci - fication of wind direction. It may, therefore, be assumed that these data represent  some kind of average of upwind, downwind, and crosswind directions. 
 January. 1977.  25. 
 4(% 
 DIMENSIONAL IMAGE IN THE RECTANGULAR COORDINATES X   Y  IS PROVIDED (IGH RESOLUTION IN SLANT 
 CT-4, pp. 41-53,  June, 1957.  69. 
 3.19b. A doppler-navigation radar with forward and rearward beams is called a Janus  system, after the Roman god who looked both forward and backward at the same time.  Assume initially that the two forward and two backward beams are symmetrically disposed  ahout the axis of the aircraft. 
 Brookner, “Array radars: An update,” Microwave J ., vol. 30, pt. I, pp. 
 6ERLAG    0REPRINTS AND 0ROCEEDINGS OF #ONFERENCES ON 2ADAR -ETEOROLOGY  nPRESENT  "OSTON !-3   0ROCEEDINGS OF %UROPEAN #ONFERENCES ON 2ADAR IN -ETEOROLOGY AND (YDROLOGY   nPRESENT   "ERLIN  'ERMANY #OPERNICUS 'MB(  - ) 3KOLNIK  )NTRODUCTION TO 2ADAR 3YSTEMS  RD %D  .EW 9ORK -C'RAW 
 SCALE IS NOT EXCEEDED ON EACH !$ CONVERTER SAMPLE 3ETTING THE SYSTEM NOISE LEVEL POWER SPECTRAL DENSITY INTO THE !$ CONVERTER  2D"   ABOVE THE !$ CONVERTER NOISE GIVES   2D "F. ".S  L O G ¤ ¦¥³ µ´ 393 )& !$#    WHERE  .393   SYSTEM NOISE AT !$ CONVERTER INPUT IN BANDWIDTH ")& #OMBINING %Q  AND  GIVES THE REQUIRED 3.2 AS   3.2 D"0# " F.2D ") 3!$#)& 393  L O G   ¤ ¦¥³ µ´         4HE  GENERATION OF BASEBAND  ) AND 1 SIGNALS FROM THE )& SAMPLED !$ CONVERTER DATA  IS PERFORMED USING DIGITAL SIGNAL PROCESSING AND CAN BE IMPLEMENTED THROUGH A VARIETY  OF APPROACHES 4WO APPROACHES ARE DESCRIBED NEXT $IGITAL $OWNCONVERSION  4HE DIGITAL DOWNCONVERSION APPROACH IS SHOWN IN  &IGURE  4HE SIGNAL IS SAMPLED BY THE !$ CONVERTER  FREQUENCY SHIFTED TO BASE 
 A  typical value of 1  µs for the pulse width of short range radar corresponds to a minimum range of  about 150  m, which is generally acc eptable. However, radars with a longer pulse width suffer a  relatively large minimum range, notably pulse compression radars, which can use pulse lengths of  the order of tens or even hundreds of microseconds. Typical pulse width τ for   Air-defense radar:          up to 800 µs  (Rmin = 120 km !)    ATC air surveillance radar:     1.5 µs   (Rmin = 250 m)    surface movement radar:        100 ns  (Rmin = 25 m)     Slant Range   Cause by the fact that the radar unit measures a  slope range, the rada r measures different ranges of  two airplanes, which exactly one above the other flies  (therefore having the same topographical distance to  the radar unit exactly). 
 A careful analysis of some of the claims  about the same radar was published by Tuley19 and is interesting reading. 21.2 PHYSICS OF PROPAGATION IN MATERIALS Introduction.  Conventional radar systems are generally not significantly affected  by the propagation characteristics of the medium the radar signals travel through, apart  from rain, absorption spectra of the atmosphere, or ionized atmospheric layers. 
 LIST  AND OTHER DATA STRUCTURES SO THAT THE ASSOCIATION PROCESS CAN  BE PERFORMED EFFICIENTLY )N ADDITION TO THE TRACK FILE  A CLUTTER FILE IS MAINTAINED !  CLUTTER NUMBER IS ASSIGNED TO EACH STATIONARY OR VERY SLOWLY MO VING ECHO !LL PARAM 
 138. Y . I. 
 AES-11, pp. 1207–1217, 1975. ch07.indd   56 12/17/07   2:15:11 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 MONOCHROMATIC %- FIELD CAN BE FULLY CHARACTERIZED BY THE FOUR 3TOKES PARAMETERS  )N TERMS OF LINEARLY POLARIZED RECEIVED DATA  THE 3TOKES PARAMETERS ARE   3% % 3% % 3% % 3(6 (6 (6    
 (9.1 ), the noise figure F,. due to the RF losses is simply  F,. = LRF (9.14) . 
 M. (3.: Rack-scattering Cross Section of a Thin, Dielectric, Spherical Shell, IRE Trans.,  vol. AP-5, pp. 
 Any use is subject to the Terms of Use as given at the website. Airborne MTI.  AIRBORNE MTI  3.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 frequency, the radar design can then be evaluated through the complete detection chain  and optimized in conjunction with any multiple PRF stagger waveforms utilized to  bridge MTI blind regions. Platform-Motion Effect. 
 The ogive, which is the type of surface found on the nose of some aircrafl, hears a  resemblance to the cone. A conformal array arranged on the aircraft nose would allow wide  coverage, provide a good aerodynamic shape, eliminate the distortion of the pattern of a  mechanically scanned antenna caused by the conventional nose-radome, and would permit  larger antenna apertures than the conventional nose-antenna configuration. The hemispheri-. 
 Afteradetection decision ismadeitmustbecorrelated againstexisting trackstodetermine whether itisanewtargetoranexisting targetalready intrack.Thisisanimportant aspectof thedetection process sincetheinitiation ofatrackafteranewtargetisdetected requires a sequence ofradardwellsthatcanconsume theresources oftheradarandthecomputer. Thetrack-illitiatioll processafteranewdetection hasbeenestablished isademanding one. Theradarmustobserve thetargetasignificant number oftimeswithinamodesttimeinterval toquickIyestahlish thetarget'sdirection oftravelandspeed. 
 P. Goetz and W. A. 
 BAND SIG 
 Additional, Doppler shift superimposes with ±f d.  Coherent Radar devices could be developed only after accurate phase preserving high -gain  amplifiers were available.  Today the transmission signal is usually derived from quartz crystal  and/or from synthesizers. 
 MEAN  CLUTTER WITH A GAUSSIAN 
 For example, from Eq. (1.9) it might be thought that the range  of a radar varies as l 112, but Eq. ( 1.10} indicates a l -112 relationship, and Eq. 
 ORATION OF WATER FROM OCEANS  LAKES  RIVERS  AND OTHER WATER RESERVOIRS $IFFERENTIAL HEATING OF LAND AND OCEAN  SURFACES PRODUCES VERTICAL AND HORIZONTAL WIND CIRCULATIONS  THAT DISTRIBUTE THE WATER VAPOR THROUGHOUT THE TROPOSPHERE 4HE WATER VAPOR CONTENT OF THE TROPOSPHERE RAPIDLY DECREASES WITH HEIGHT !T AN ALTITUDE OF  KILOMETERS  THE WATER VAPOR CONTENT IS APPROXIMATELY HALF OF THE SURFACE CONTENT !T THE TROPOPAUSE  THE CONTENT IS ONLY A FEW THOUSANDTHS OF WHAT IT IS AT THE SURFACE )N   THE 7EATHER "UREAU  AT THE REQUEST OF THE .ATIONAL !DVISORY #OMMITTEE FOR  !ERONAUTICS .!#!   PREPARED A STANDARD ATMOSPHERE FOR SCIENTIFIC AND ENGINEERING USE BASED PRIMARILY ON THE AVERAGE CONDITIONS OVER THE 5NITED 3TATES AT LATITUDE  )N   THE COMPUTATIONS WERE EXTENDED TO   METERS USING CONSTANTS ADOPTED BY THE .!#! !N EXTENSION OF THE STANDARD ATMOSPHERE TO   METERS WAS PREPARED IN . 
 BEAM TUBE  IS CAPABLE OF HIGH POWER  BECAUSE THE GENERATION OF THE ELECTRON BEAM  ITS INTERACTION WITH THE ELECTROMAGNETIC FIELD  AND THE COLLECTION OF THE SPENT ELECTRONS ARE PERFORMED IN SEPARATE PARTS OF THE TUBE WHERE THE GENERATED HEAT CAN BE DISSIPATED EFFECTIVELY 4HE KLYSTRON AND OTHER LINEAR 
 AES-8. pp. 517-527, July. 
 Pierson and L. Moskowitz, “A proposed spectral form for fully developed wind seas  based on the similarity theory of S. A. 
 wall configt~rations described above arc applicahlc to aisbor~ie radars, bill anotllcl. approacl~ is  based on the fact that a metal sheet with periodically spaced slots exhibits a bandpass charac-  teristic. Thus thin metallic radomes, pierced with many openings (slots) to makeit transparent  to microwaves, offer the possibility of overcoming the mecl~anical limitations of dielectric  radomes, yet result in good eiectrical properties.'06 lo* A metallic structure not only has the  potential for greater mechanical strength than dielectric radomes and to better dis[ribtrtc:  frictionally-induced heating, bir t it sliould be able to better withstand the stresses caused by  rain, hail, dust, and lightning. 
 ARY  BEAM 4HE SECOND PROPERTY DEFINES THE SCANNING 4HE REFLECTOR SCAN ANGLE   PR  IS  DEFINED BY THE FOLLOWING EQUATION   PR y PF -    WHERE PF IS THE FEED SCAN ANGLE  &OR EXAMPLE  IF THE MAGNIFICATION FACT OR IS  AND THE  %3! FEED ARRAY IS SCANNED   THE REFLECTOR BEAM WILL SCAN APPROXIMATELY . £Ó°Ó{  2!$!2 (!.$"//+  3CAN ABERRATIONS LEAD TO MODERATELY HIGHER SCAN LOSSES AND SLIG HT BEAM SCAN ANGLE  DEVIATIONS FROM THOSE PREDICTED BY %QS   AND  WHEN IDEAL %3! PLANE WAVE  EXCITATIONS  IE  LINEAR PHASE SLOPE  ARE APPLIED (OWEVER  THE AMPLITUDE AND PHASE  CONTROLS IN THE %3! ALLOW FOR SCAN ABERRATION COMPENSATION VIA CONJUGATE MATCHING OF THE APERTURE FIELDS  4HUS  THE USE OF AN %3! FEED ENABLES RECOVERY OF SCAN LOSSES  RESULTING FROM ABERRATIONS IN THE SYSTEM #ONFOCAL REFLECTOR ARCHITECTURES HAVE BEEN THE SUBJECT OF STUDY AND ANALYSIS FOR  MANY YEARS AND NUMEROUS DEMONSTRATION SYSTEMS HAVE ALSO BEEN DEVELOPEDn  !LTHOUGH CONFOCAL REFLECTORS HAVE NOT BEEN ADOPTED FOR SIGNIFICANT USAGE IN OPERA 
 24.56  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 scenarios (multiple clutter sources, user defined trajectory) in terms of signal-to-dis - turbance power ratio and detection probability; and radar range and height accuracy  calculation, radar resolution evaluations employing suitable data extracting logics.  The RWS suite consists of the following main modules: C\C ++ and Fortran (to calcu - late special functions like Gamma and Bessel K) coded libraries; a standard library of  Windows APIs (Application Programming Interfaces) to draw the coverage diagrams;  a template library to implement the matrix algebra; an application based on MS Office  Excel to code the Blake Chart†; a set of Visual Basic tools to evaluate some aspects  of radar performance (e.g., ADC jitter, atmospheric loss, tapering loss, etc.); and an  unformatted archive of radar data, as simple ASCII files, pertinent to performance,  environment, trajectories, terrain height, and waveform. User-friendly interfaces run  on low-cost platforms (PC) and popular environments (Win98, WinNT, Win2000,  Windows XP, Vista) for users and developers. 
 Electron-bombarded semiconductor device.47TheEBS,oreiectron-bombarded semiconduc­ tor,isahybriddevicethatcombines semiconductor andvacuum-tube technology. Itcontains aheatedcathode thatgenerates anelectron beamwhichstrikesasemiconductor diodeathigh. energy (typically 10 to 15 keV). 
 In addition, the burnthrough mode is not  effective against chaff, decoys, repeaters, spoofers, and so on. More effective is the use of complex, variable, and dissimilar transmitted signals that  place a maximum burden on ESM and ECM. Different ways of operation refer to the  change of the transmitted frequency in frequency-agility or frequency-diversity modes  or to the use of wide instantaneous bandwidth.131–133 Frequency agility  usually refers to  the radar’s ability to change the transmitter frequency on a pulse-to-pulse or a batch- to-batch basis. 
 9, pp. 839–847, 1988. 124. 
 The desirable lower limit was expected tobesetonly from considerations ofapractical upper limit toantenna size and requirements ofmechanical accuracy. Results obtained fully confirmed these conclusions forbearnwidths down to1°athalf power, but inalater section ofthis chapter weshall seethat qualifications may beintroduced iffuture development isextended to beams much narrower. Miscellaneous Requirements. 
 SEC. 15.9] CHOICE OF WAVELENGTH 605 3.Beamwidth. Regardless ofwavelength choice, the maximum antenna width foratransportable air-surveillance setappears to beabout 35ft. 
 These LOs are gener - ally also used in the exciter to upconvert modulated waveforms to RF for output to  the transmitter. In many early radars, the only function of the local oscillators was conversion of  the input signal frequency to the correct intermediate frequency. Many modern radar  systems, however, coherently process a series of returns from a target. 
 9.6DVPLEXERS ANDRECEIVER PROTECTORS Theduplexer isthedevicethatallowsasingleantenna toserveboththetransmitter andthe receiver. Ontransmission itmustprotectthereceiver fromburnout ordamage, andon reception itmustchannel theechosignaltothereceiver. Duplexers, especially forhigh-power applications, sometimes employ aformofgas-discharge device.Solid-state devicesarealso utilized. 
 2.8(1.  The post-detection integration loss described by Fig. 2.8 assumes a perfect integraior. 
 BASED OR SHIP 
 The echo signal is therefore independent of range for a constant­ altitude target.  In practice, the power received from an antenna with a cosecant-squared pattern is not  truly independent of range because of the simplifying assumptions made. The cross section er  varies with the viewing aspect, the earth is not flat, and the radiation pattern of any real  antenna can be made to only approxfmate the desired cosecant-squared pattern. 
 TION OF THE CLUTTER POWER SPECTRAL DENSITY AS A FUNCTION OF THESE PARAMETERS FOR ANY GIVEN SEA STATE  TAKING INTO ACCOUNT ANY INFORMATION ABOUT TARGET COURSE  SPEED  AND 2#3 ! VERY IMPORTANT OPERATIONAL CONSIDERATION HERE IS THE POTENTIAL FOR AN ADVERSARY  TO EXPLOIT THE SEA CLUTTER SPECTRUM BY CONTRIVING TO PLACE HIS SHIP ECHO AT THE "RAGG FREQUENCY WHERE IT WOULD BE OBSCURED BY SEA CLUTTER 4HE ADVERSARY CAN ACHIEVE THIS BY CHOOSING ANY COMBINATION  OF COURSE AND SPEED  THAT MAKES THE VELOCITY COMPONENT  TOWARD THE RADAR EQUAL TO THE EQUIVALENT PHASE VELOCITY OF THE "RAGG PEAK 4HE RADAR OPERATOR MUST COUNTER THIS BY EXPLOITING HIS UNDERSTANDING OF THE DETAILED STRUCTURE OF THE SPECTRUM AND ITS VARIATION WITH RADAR FREQUENCY TO UNMASK THE TARGET 2ADAR /CEANOGRAPHY  4HE EXISTENCE OF THE RELATION EXPRESSED IN %Q   BETWEEN THE SEA SURFACE REPRESENTATION AS A DIRECTIONAL WAVE SPECTRUM  3 FJ AND THE  DOPPLER SPECTRUM MEASURED BY AN (& RADAR PROVIDES AN OPPORTUNITY TO DETERMINE THE DETAILED STATE OF THE SEA SURFACE BY REMOTE SENSING WITH SKYWAVE OR SURFACE WAVE  RADAR )N ORDER TO EXTRACT SEA PARAMETERS FROM RADAR DOPPLER SPECTRA  AND TO OPTIMIZE THE CHOICE OF RADAR PARAMETERS FOR THE RADARS SURVEILLANCE MISSIONS  IT IS HELPFUL TO UNDERSTAND SOME ELEMENTARY OCEANOGRAPHY 4HE OCEAN WAVES THAT CONTRIBUTE MOST TO THE (& RADAR RETURNS HAVE WAVELENGTHS IN  THE RANGE OF n M THESE WAVES ARE EXCITED BY THE SURFACE WINDS )F A WIND BLOWS AT A CONSTANT VELOCITY LONG ENOUGH AND OVER SUFFICIENT FETCH THE DISTANCE OVER WHICH THE WIND IS BLOWING   A STEADY 
 I. Skolnik, Introduction to Radar Systems , 2nd Ed., New York: McGraw-Hill Book Company,  1980, pp. 504–506. 
 166-171; Oct. 23-25, 1973, IEE Conference Publication No. 105. 
 The average power required for the planar array of the dome  antenna is approximately the sum of the average powers required for each of the individual  arrays, assuming comparable performance.  It has been claimed that the dome antenna is of less cost than four arrays of conventional  design covering the same volume. However, any comparison of this technique with conven-  tional antennas must be done on the basis of the entire radar system and its intended applica-  tion, not just the antenna. 
 Ifthe regulator isremoved from the circuit, the alternator will still generate avoltage because thefield current will flow through themotor- regulating field tothe generator field. Inthe case ofinverters not. SEC. 
 Ilclirikc: Rcal-.l'iriic Iracking Filter Evaluatio~i arid Selcctio~i for Tactical  Applic;~tior\s. 1l:I:E 7'r.(rrrs.. vol. 
 Despite the power of this technique, the spatial resolution in the derived three-dimensional motion fields is generally not better than of the order of 2 km. The reasons for this are several. The finite beamwidth limits the resolution available at longer ranges. 
 Tech. Rept. 155 SU - SEL-70-034, Stanford  University, June 1970. 
 17.5a—Jittered-pulse system, transmitting station,. SEC.17.5] THEMETHOD OFINCREMENTAL ANGLE 693 PointXFig.(17.3) I 1 Pulse Cathode Band stretcher follower pass V,h finerb‘otor‘--e H~ ‘+--2- Afterfilter ~.; ~ ‘—’’’—’” FICA 17.5b.—Jittered-pulse system, receiving station. expressed byasinusoidal variation inthe relative timing ofapair of pulses appearing ineach pulse cycle. 
 The resulting single  blind speed due to main-beam clutter permits as wide of a clutter rejection notch  as required to reject main-beam clutter or ground moving targets and still not result  in doppler blind speeds for targets of interest. M-of-N ranging provides better range  measurement accuracy than linear FM ranging used in HRWS. The PRFs used in a  dwell must be chosen to resolve the high number of range ambiguities within the  instrumented range. 
 BEAM CLUTTER IN SEARCH OR THE TARGET IN 3INGLE 
 L LLLL LLLsamples of the digital signal SUT-TVcomparator target identification. .SUT TVs t r o a g e . .A/2+3 A/2+1 A/2 sorting of the sum-values Si in decreasing order S1 ≥ S2 ≥ . 
 TheMTIcancellation mayalsobedoneatiFratherthaninthevideoafterthephase detector.8Although theremaybesomeadvantages inIFcancellation (suchasnoblind phases), itismorecomplicated thanvideocancellation. Itisdifficult forIFcancelers to compete withtheflexibility andconvenience ofdigitalprocessing containing 1andQchannels. FMdelay-line cancelers havealsobeenconsidered forMTIapplication. 
 (From Ref. 7.) an ABSF of 1.6 dB and the detection curves in Chap. 2. 
 6.5. Reflectors with the longer focal lengths, which are flattest and introduce the least distortion of polarization and of off-axis beams, require the narrowest primary beams and therefore the largest feeds. For example, the size of a horn to feed a reflector of flD = 1.0 is approximately 4 times that of a feed for a reflector of f/D = 0.25. 
 The thresholds are reached when diode D2 carries either all or none of the current. If the voltage drops across the diodes are neglected, this occurs when *'-*'=* KaT*;) (3'10) Signals above the threshold in magnitude are attenuated by a factor RI(R + /?f), the reciprocal of the amplifier gain. The incremental gain in this region is there- fore unity. 
 14. Zhou Wenyu and Mao Xu, “Bistatic FMCW OTH-B experimental radar,” Proc. Int. 
 However, the five-horn feed is a practical choice between com - plexity and efficiency. It has been used in several instrumentation radars including  the AN/FPQ-6, AN/FPQ-10, AN/TPQ-18, andAN/MPS-367,8 and in the AN/TPQ-27  tactical precision-tracking radar.9 The multimode feed technique can be expanded to other higher-order modes for  error sensing and E-field shaping.10,11,12 The difference signals are contained in unsym - metrical modes such as the TE20 mode for H-plane error sensing and combined TE11  and TM11 modes for E-plane error sensing. These modes provide the difference sig - nals, and no comparators are used.10 Generally, mode coupling devices can give good  performance in separating the symmetrical and unsymmetrical modes without signifi - cant cross-coupling problems. 
 Types of Radar Transmitters.  The very first “radars,” such as those used by  Heinrich Hertz (the first radar scientist) in the late 1880s and the shipboard radar  invented by Christian Hulsmeyer (the first radar engineer) in the early 1900s used the  spark gap  as the transmitter. It was a very poor transmitter, but that is not unusual in the  early days of a new and different development. 
 POINT PROCESSORS 0OSTDETECTION INTEGRATION 0$)  MAY BE USED WHERE EACH RANGE 
 TIONAL 3," APPROACH SUCH AS THE ONE ILLUSTRATED IN &IGURE   OPERATING SO THAT IF INTERFERINGREPEATER JAMMER POWER IS DETECTED AT A PARTICULAR RANGE CELL  THEN THAT RANGE CELL HAS TO BE EFFECTIVELY BLANKED 4HE 2&- 
 As the CPI becomes smaller (^1O), it will become important to consider spe- cial designs of the individual filters to match the specific clutter suppression re- quirements at different doppler frequencies in order to achieve better overall per- formance. While some systematic procedures are available for designing FIR filters subject to specific passband and stopband constraints, the straightforward approach for small CPIs is to use an empirical approach in which the zeros of each filter are adjusted until the desired response is obtained. An example of such filter designs is presented below. 
 TER WHERE THE LOSS IN RANGE PERFORMANCE MIGHT BE OFFSET BY AN INCREASE IN DWELL TIME ON TARGET  AS DETAILED SUBSEQUENTLY 4IME 
 A SINGLE-VALVE TIME-BASE GENERATOR,  FUNCTIONING AS A SQUEGGING OSCILLATOR  which, of course, are principally controlled by the values  of L and C. This latter oscillatory frequency must be  higher than the sweep frequency to avoid interference.  The circuit oscillates, and the grid of the valve rapidly  becomes negative until oscillation is checked. 
 In Fig. 7.17 the feeds are shown on a straight line, but in the parabolic torus they would  lie on the arc of a circle.  The many feed horns plus all the transmission lines of the organ-pipe scanner result in a  relatively large structure with significant aperture blocking. 
 They areinstantly readable byrapidly scanning radars, but. have thedisadvantage ofbeing more subject toconfusion byoverlapping patterns, when numerous beacons arepresent atnearly thesame bearing, than arereplies that give simpler patterns. VoiceCommunication. 
 R. Rosenzweig: Learn the Language of Mixer Specification, Microwai,es, vol.  17, pp. 
 ETY OF RADARS 4HE DASHED PORTIONS OF THE CURVES ARE REGIONS OF UNCERTAINTY BECAUSE OF SIGNIFICANT VARIATIONS OF REFLECTION FOR A GIVEN SEA STATE )N THE INTERMEDIATE REGION  THE ERROR INCREASES TO A PEAK AT TARGET ELEVATIONS OF  ABOUT  BEAMWIDTH 4HE PEAK VALUE IS DEPENDENT ON SEVERAL FACTORS INCLUDING SURFACE ROUGHNESS WHICH  IN PART  DETERMINES THE VALUE OF  Q   SERVO BANDWIDTH  AND ANTENNA  CHARACTERISTICS IN THE REGION 4HE ERRORS ARE SEVERE  AND WITH  UN 
 B = filter bandwidth.  same as the signal s(t) for which the matched filter was designed (that is, the noise is assumed  negligible), the output would be the autocorrelation function. The autocorrelation function of  a rectangular pulse of width r is a triangle whose base is of width 2r. 
  
 Even if the RF amplifier itself has more than adequate dynamic range, the mixer dynamic range has been com- promised, as indicated below: Ratio of front-end noise to mixer noise 6 dB 1OdB 13.3 dB Sacrifice in mixer dynamic range 7 dB 10.4 dB 13.5 dB Degradation of system noise temperature by 1 dB 0.4 dB 0.2 dB mixer noise Definitions. Section 2.5 defined the noise parameters of a receiver in simple terms. Dynamic range, which represents the range of signal strength over which the receiver will perform as expected, is more difficult to define. 
 J., and J. P. Petro: On the RF Frequency Dependence of the Scattered Spectral Energy  Produced by Intermittent Contacts Among Elements of aTarget, IEEE Trans., vol. 
 Nevertheless, the angle measurement is an integral part of most surveillance and tracking ra- dars. Size. If the radar has sufficient resolution, it can provide a measurement of the target's extent, or size. 
 For the determination ofangle, ithas been most usual inthe past touse mechanical indices: either asetoffixed indices engraved ona transparent overlay, oramovable mechanical cursor. These can give errors due toparallax and toinaccuracies inthedisplay. More recently, electronic indices have begun toreplace mechanical range markers. 
 B.. 
 This implies that the  minimum rms range error for a perfectly rectangular pulse is zero and that the range measure­ ment can be made with no error. In practice, however, pulses are not perfectly rectangular  since a zero rise time or a zero fall time requires an infinite bandwidth. Finite bandwidths  result in finite rise times and finite /J2•  In order to compute /J2 (and the range error) for a practical" rectangular" pulse, it will be  assumed that the pulse spectrum is of the form S{f) = (sin rrfr)/nf, just as with the perfectly  rectangular pulse of width r, but that the bandwidth is limited to a finite value Bas shown in  Fig. 
 I,. R.. I). 
 The airborne radomemustbestrongenoughtoformapartoftheaircraftstructure andusually mustbedesigned toconform totheaerodynamic shapeoftheaircraft,missile,orspacevehicle inwhichitistooperate. Aproperly designed radomeshoulddistorttheantenna patternaslittleaspossible. The presence ofaradomecanaffectthegain,beamwidth, sidelobe level,andthedirection ofthe. 
 After  many other approaches, it was recognized that if one used the clutter return rather than  the transmit pulse to phase-lock the radar to the clutter filter, one could center the clut - ter in the filter stopband. The clutter phase varies from range cell to range cell owing  to the distribution of the location of the scatterers in azimuth. Hence, it is necessary  to average the return for as long an interval as possible. 
  
 23.17  Precipitation Measurement  ................................  23.18 . This page has been reformatted by Knovel to provide easier navigation. 
 J. McBride, Jr., “Methods for increasing the bandwidth of high  power microwave amplifiers,” IRE WESCON Conv. Rec . 
 STATE PHASED ARRAY RADAR  !S A RESULT OF CONTINUOUS DEVELOPMENT  PHASED  ARRAYS ARE USED IN MULTIPLE MILITARY AND COMMUNICATIONS SYSTEMS 4HE ADVANTAGES OF A PHASED ARRAY TRANSMITTER INCLUDE   THE ABILITY TO HAVE MULTIPLE INDEPENDENTLY STEERED BEAMS FROM A SINGLE APERTURE    THE SPEED OF ELECTRONIC VERSUS MECHANI 
 Theeffectofpractical elements withnonisotropic patterns willbe considered later.Thearrayisshownasareceiving antenna forconvenience, butbecauseofthe reciprocity principle, theresultsobtained applyequallywelltoatransmitting antenna. The outputsofalltheelements aresummed vialinesofequallengthtogiveasumoutputvoltage Ea.Element 1willbetakenasthereference signalwithzerophase.Thedifference inthephase ofthesignalsinadjacent elements ist/J=2n(dj,.l)sin0,where0isthedirection oftheincoming radiation. Itisfurtherassumed thattheamplitudes andphasesofthesignalsateachelement areweighted uniformly. 
 141. Sensors 2019 ,19, 2921 5. Accuracy Analysis We extract the DEM using the SAR images imaged on the reference plane. 
 2. The standing-wave pattern on the cable feeding the reference signal to the receiver, due to  poor mixer match.  3. 
 High-power CWradarsforthedetection ofaircraftandother targetshavebeendeveloped andhavebeenusedinsuchsystemsastheHawkmissilesystems (Fig.3.3).However, thedifficulty ofeliminating theleakageofthetransmitter signalintothe receiverhaslimitedtheutilityofunmodulated CWradarformanylong-range applications. A notableexception istheSpaceSurveillance System(Spasur) forthedetection ofsatellites. 26.27 TheCWtransmitter ofSpasurat216MHzradiates apowerofuptoonemegawatt froman antenna almosttwomileslongtoproduce anarrow,vertically lookingfanbeam.Thereceiver isseparated fromthetransmitter byadistance ofseveralhundred miles.Eachreceiversite consistsofaninterferometer antenna toobtainananglemeasurement intheplaneofthefan beam.Therearethreesetsoftransmitter-receiver stations toprovide fencecoverage ofthe southern UnitedStates. 
 2.7  determines the signal-to-noise ratio. This is the signal-to-noise ratio that is used in the equa­ tion for minimum detectable signal [Eq. (2.6)]. 
 20.4 THE IONOSPHERE   AND RADIOWAVE PROPAGATION The solar activity that drives the ionization of the Earth’s upper atmosphere is variable  on a diurnal, seasonal, and long-term basis with a superimposed random component and  occasional major storms and other disturbances. Further, the Earth’s lower atmosphere  is coupled to the ionosphere by a variety of upward-propagating wave and radiation  processes, whereas the Earth’s magnetosphere, the region beyond the ionosphere where  the solar wind interacts with the Earth’s magnetic field, is the source or conduit for  corresponding perturbations from above. The ionospheric response to all these external  forces is governed not only by inertial effects but also by chemical reactions and by the  embedded time-varying electric and magnetic fields that link the ionospheric plasma  to the Earth and to the interplanetary medium. 
 Hence, there is no power dissipation in the amplifier while  the transmitter is operating in this mode. ● Only one power supply voltage is necessary for the collector terminal of the transis - tor. The Class-C operation is a self-bias, wherein the transistor draws collector cur - rent only when the RF voltage swing on the input exceeds the built-in potential of  the emitter-base junction. 
 Targets measured indoors are placed much closer to the radar than those measured  outdoors, and useful measurements may be made by using much less radiated power.  Early indoor instrumentation radars relied on simple CW sources, and undesired cham - ber reflections were suppressed by a cancellation process. The procedure is to prepare  the chamber for a measurement in every respect except for the installation of the target  on its support fixture. 
 IARIES FOR THE *INDALEE RADAR CAN BE FOUND IN %ARL AND 7ARD   4RADITIONALLY  THE CONTROL MECHANISM HAS BEEN THE EXPERT RADAR  OPERATOR &OR MANY  REASONS  THIS IS NOT WHOLLY SATISFACTORY  SO VARIOUS ALTERNATIVES HAVE BEEN EXPLORED  INCLUDING PACKAGED hRECIPESv THAT CAN  BE INVOKED BY LESS SKILLE D OPERATORS AND EXPERT  SYSTEMS IMPLEMENTED WITH ARTIFICIAL INTELLIGENCE CONSTRUCTS !PART FROM THE NEED TO ADAPT TO THE CHANGING IONOSPHERE AND NOISE ENVIRONMENT   (& RADARS ARE FREQUENTLY TASKED WITH A VARIETY OF MISSIONS TO BE CONDUCTED MORE OR LESS CONCURRENTLY  WITH TIME 
 GATION  -(Z TO  '(Z  MODEL FOR USE IN .AVY SYSTEMS "OTH !2%03 AND !0- ARE ACCREDITED WITHIN THE .AVY -ODELING AND 3IMULATION /FFICE .-3/  !2%03 IS ALSO A .ORTH !TLANTIC 4REATY /RGANIZATION .!4/  APPLICATION  APPROVED BY THE -ILITARY #OMMITTEE -ETEOROLOGICAL 'ROUP7ORKING 'ROUP  "ATTLE !REA -ETEOROLOGICAL 3YSTEMS AND 3UPPORT PLUS WITH 0ARTNERS !2%03 VERSION  CONTAINS SEVERAL %- PROPAGATION MODELS FOR APPLICATIONS AT  VARIOUS FREQUENCIES &OR FREQUENCIES OF  -(Z TO  '(Z  !2%03 USES THE !0- &OR (& SKY WAVE COMMUNICATIONS  !2%03 USES AN (& MODELING SUITE   CONSISTING OF A  FULLY $ IONOSPHERE RAY TRACE MODEL  AN (& FIELD STRENGTH MODEL  AND AN (& NOISE MODEL )N ADDITION TO THESE %- PROPAGATION MODELS  !2%03 MAY OPTIONALLY USE TWO INTERNATIONALLY RECOGNIZED IONOSPHERE MODELS  THE 0ARAMETERIZED )ONOSPHERIC -ODEL 0)-   AND THE )NTERNATIONAL 2EFERENCE )ONOSPHERE )2)  )N ADDITION TO THE PROPAGA 
 ING OF THE PULSE COMPRESSION FILTER TO REDUCE TIME RANGE  SIDELOBES %CLIPSING AND 2ANGE 'ATE 3TRADDLE ,OSS  4HE LARGE AMOUNT OF RANGE AMBIGUITY  INHERENT IN PULSE DOPPLER WAVEFORMS RESULTS IN THE POSSIBLE ECLIPSING OF TARGET RETURNS . 
 52, pp. 93–101, February 1982. 118. 
   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x° ! MAJOR ENABLER FOR !%3!S IS THE STATE OF THE ART IN MICROWAVE INTEGRATED CIRCUITS  4HIS HAS FOLLOWED THE DRAMATIC COST AND PERFORMANCE GAINS AVAILABLE IN MOST SEMICON 
 The experiment contained two parts. First, we used the ArcSAR images of the distributed scenes for interference to extract the DEM image of the scenes. Then, the extracted DEM image was transformed from the slant range to the ground range using the polar coordinate transformation method proposed in Section 4.2. 
 KGI I. II I.   C O S     
   ")34!4)# 2!$!2   ÓÎ°Î 4HE FOREGOING DEFINITIONS ARE BROAD AND TRADITIONALn BUT ARE BY NO MEANS UNI 
 The maximum usable angle ofelevation was extended by using two receiving antennas 90ftand 45fthigh respectively (the “B” system). Figure 6.17 shows the goniometer readings forthe Aand B systems asafunction ofangle ofelevation. The curves areplotted fora flatsiteand-for antennas perfectly matched totheir feeders. 
 However, rotating winds or vortices can be de- tected and their intensities measured by simply measuring the change in radial . FIG. 23.3 Measurement of rotation or azimuthal shear in a mesocyclone. 
 RECEIVERS, DISPLAYS, AND DUPLEXERS 3S5  £-scope. An intensity-modulated rectangular display with distance indicated by the horizontal coordinate  and elevation angle by the vertical coordinate: Similarto the RHI in which target height or altitude is  the vertical coordinate.  F-Scope. 
 RELATED SOURCES &IGURE  IS AN EXAMPLE OF THE MEASURED TRACKING PERFORMANCE OF AN !.&03 
 RADAR CLUTIER 509  Table 13.3 Radar cross sections of birds91  Frequency Mean radar Median radar  Bird band cross sect ion (cm2) cross section (cm2)  (irackle X 16 6.9 s 25 12  UHF 0.57 0.45  Sparrow X 1.6 0.8 s 14 l l  UflF 0.02 0.02  Pigeon X 15 6.4 s 80 32  UHF I I 8.0  described statistically. There is some evidence to indicate that the probability density function  for the radar cross section of (or received power from) a single bird in flight is log-normal. The  mean-to-median ratio of the cross section. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 8.6 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 FIGURE   8. 
 36–48, 1987. 64. J. 
 Unfortunately, theeffortrequired tospecifycompletely theeffectsofallradarpa­ rameters tothedegreeofaccuracy required forrangeprediction isusuallynoteconomically justified. Acompromise isalwaysnecessary between whatonewouldliketohaveandwhat onecanactually getwithreasonable effort.Thiswillbebetterappreciated asweproceed through thechapterandnotethevariousfactorsthatmustbetakenintoaccount. Acomplete anddetailed discussion ofallthosefactorsthatinfluence theprediction of radarrangeisbeyondthescopeofasinglechapter.Forthisreasonmanysubjectswillappear tobetreatedonlylightly.Thisisdeliberate andisnecessitated bybrevity.Moredetailed information willbefoundinsomeofthesubsequent chapters orinthereferences listedatthe endofthechapter. 
   
 ;irici K. S. Kelleher: Recent Electronic Scanning Developments. 
 A knowledge of the transmitted signal is necessary at the receiver site if the maximum  information is to be extracted from the scattered signal. The transmitted frequency is needed to  determine the doppler frequency shirt. A time or phase reference is also required if the total  scattered path length (D1 + D,) is to be measured. 
 YEAR LEGACY OF SUCCESS v  2EMOTE  3ENSING OF %NVIRONMENT  VOL   PP n     - $ 'RIFFIN AND * 2 &RENCH   3PACE 6EHICLE $ESIGN  !MERICAN )NSTITUTE OF !ERONAUTICS AND  !STRONAUTICS     6 * 0ISACANE  &UNDAMENTALS OF 3PACE 3YSTEMS  ND %D  /XFORD /XFORD 5NIVERSITY 0RESS     & - (ENDERSON AND ! * ,EWIS EDS    0RINCIPLES  AND  !PPLICATIONS  OF  )MAGING  2ADAR     .EW 9ORK * 7ILEY  3ONS )NC  . 
 AIDED DESIGN PROCESS  AND AZIMUTH SIDELOBES ARE LOWERED BY OFFSETTING THE FEED SO THERE IS NO BLOCKAGE 4WO LINEAR OR CIRCULARLY POLARIZED ELEVATION BEAMS ARE PRODUCED BY USING TWO FEEDHORNS /NE BEAM IS CLOSE TO THE HORIZON FOR CLOSE IN TARGETS  AND THE SECOND IS HIGHER IN ELEVATION  SO IT RECEIVES LESS GROUND CLUTTER FOR LONG RANGE TARGETS /NE TYPICAL CHARACTERISTIC OF SHAPED REFLECTORS IS LOWER APERTURE EFFICIENCY  'ENERALLY  THE SURFACE SHAPING PROCESS SPOILS THE APERTURE PHASE AND BROADENS THE BEAM THEREBY INHERENTLY REDUCING THE APER 
 The limitation in this case is the thermal noise seen by the antennii and  the ohmic losses in the transmission line.  For radar receivers of the superheterodyne type (the type of receiver used for most radar  applications), the receiver bandwidth is approximately that of the intermediate-freqire~lcy  stages. It should be cautioned that the bandwidth B, of Eq. 
 aircraftZ8 is sllown in Fig. 2.16. The aircraft is the B-26, a World War I1 medium-range  two-engine bomber. 
 The cathode circuits were also tuned and providedwith preset adjustments. The transmitter operated on a squegging principle controlled by an RC ﬁlter connected to the valve grids and the power rail. The tuning of the transmitter circuitswas apparently very dif ﬁcult, with much interaction between the tuning settings, the antenna load and the power supply voltages. 
 It should be noted, however, that owing to the extreme variability of the characteristics of real clutter returns (power level, doppler shift, spectrum shape, spectral width, etc.) any attempt to actually approximate the performance of such optimum filters for the detection of targets in clutter re- quires the use of adaptive methods. The adaptive methods must estimate the un- known clutter statistics and subsequently implement the corresponding optimum filter. The design of such adaptive MTI systems is discussed in Sec. 
 The  noise figure of an image-recovery circuit (Fig. 9.4) is competitive with other receiver front-  ends. The irkage-recovery mixer is attractive as a receiver front-end because of its high dy-  namic range, low intermodulation prcxlucts, less susceptibility to burnout, and less cost as  compared to other front-ends.13  Diode  mixer 7-  RF  input junction  Diode  mlxer Figure 9.3 Image-recovery mixer. 
 Despite the inexactness of range predic- tions in the absolute sense, the error can be made small enough that the calcu- lated range is a good indication of the performance to be expected under average environmental conditions. Section 2.10 is a more detailed discussion of prediction accuracy. Attempts to evaluate range prediction factors accurately, to better than per- haps 1 dB, are sometimes disparaged on the grounds that some factors are un- . 
 It was also reported that the antenna tilt appeared to be about 2 °down. As discussed later, setting the correct tilt when installing the antennas seems to have been a recurring problem. Further trials of a production installation were undertaken by CCDU in April 1944 [ 11]. 
 IEEE Antennas Wirel. Propag. Lett. 
 MENT  MONOPULSE ANGLE ACCURACY  MAXIMIZING THE RECEIVER DYNAMIC RANGE  AND NOISE LEVEL CONTROL $IGITAL GAIN CONTROL PERMITS THE CALIBRATION OF  RECEIVER GAIN BY INJECT 
  -)4 
 ● Identification and exploration of possible solutions .  This includes understanding the advantages and limitations of the various pos - sible solutions. ● Selection of the optimum or near optimum solution . 
 203-2~2. Also Trunk, G. V.: Survey  of Radar Signal Processing, Naval Research Laboratory Report 8117, Washington, D.C., June 21,  1977. 
 25.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 by digitized sine and cosine waveforms for the modulation carrier frequency, produc - ing a complex modulated IF as an output. These signals are digitally summed, con - verted to analog through a DAC, and passed through a bandpass filter to produce an  IF output. For large upsampling ratios, a cascaded-integrator comb (CIC) interpolator,  described in the next section, provides an efficient implementation. 
 PULSE PHASE  CHANGES IN THE TRANSMITTED PULSE CAN BE INTRODUCED BY THE PULSED AMPLIFIER 4HE  MOST COMMON CAUSE OF A POWER AMPLIFIER INTRODUCING PHASE CHANGES IS RIPPLE ON THE  HIGH 
 Easton, R. L.: The Role of Time/Frequency in Navy Navigation Satellites, Proc. IEEE, vol. 
 IIIC [ 21] it had been recommended that the Switch unit be installed to the left of the indicator unit, with the range drum vertical and as near to the table aspossible to facilitate use of the range marker control (at the bottom of the switch unit). In [ 20] it was recommended that a guard be placed over the automatic attenuator control, to prevent accidental loss of power output. A continuing problem with the antenna tilt and aircraft trim was also reported, with aAirborne Maritime Surveillance Radar, Volume 1 4-20. 
 82-87, April, 1961.  38. MacWilliams. 
 FUL ARE THE MAPS OF I  %XCESS 0OWER AND II  /PTIMUM &REQUENCY  4HE %XCESS 0OWER  PARAMETER IS CONSTRUCTED AS FOLLOWS #ONSIDER A SPECIFIC TARGET WHOSE 2#3 IS KNOWN OR ESTIMATED AS A FUNCTION OF FREQUENCY 3UPPOSE A PREDICTION OF MEDIAN RADAR DETEC 
 INTERFERENCE RATIO (OWEVER  COMPLEX VARIABLES ARE EMPLOYED HERE RATHER  THAN REAL VARIABLES 4HE INTERFERENCE COVARIANCE MATRIX IS FURTHER DESCRIBED IN TERMS OF THE INDIVIDUAL NOISE  JAMMING  CLUTTER  AND SIGNAL CONTRIBUTIONS   2 R   . )   +:   23    WHERE . IS RECEIVER NOISE POWER   +: IS THE COVARIANCE MATRIX FOR CLUTTER TEMPORALLY COR 
 TO 
 ELEVATION TARGETS AND THE LINEARLY DECREASING ERROR VERSUS TARGET ELEVATION  PREDICTED BY THE ABOVE EQUATION  FOR VERY LOW 
 J. Button. and L. 
 W. Burgess, and R. J. 
 TIME MAP OF OPTIMUM FREQUENCY IN -(Z TO DETECT A SPECIFIC TARGET  AS A  FUNCTION OF RANGE AND TIME 
 K., and L. F. Sheats: Application of Pipeline FFT Technology in Radar Signal and Data Processing, EASCON Rec., pp. 
 AES-9, pp. 512-519, July,  197J  77 Singer. R A .. 
 Oliner and G. H. Knittel (eds.),  Norwood, MA: Artech House, 1972, pp. 
 54. J. Hudson, Adaptive Array Principles , London: Peter Peregrinus Ltd., 1981. 
 With appropriate feed systems, both are  capable of providing vertical and horizontal polarization independently and may be  combined to provide any desired polarization, including circular. Such polarization  diversity adds considerable complexity, requiring two feed systems or switches at the  radiating element level. Circular Polarization . 
 SIBLE TARGETS TO BE CONFIRMED BY A RETURN OBSERVATION WITH A HIGHER THRESHOLD   IT ALSO USES MULTIPLE PHASE CENTER DISCRIMINANTS AS WELL AS NEAR SIDELOBE THRESHOLD MULTIPLI 
 The waveform was modulated CW. The  receiver front end was a tunnel diode amplifier, which maintained the noise figure to  be less than 5.7 dB at all operating temperatures. Mean input power was 136 W dc;  the instrument mass was 102 kg. 
 8 n  -ODERATEn(IGH 4!$)83 5(&  -ODERATE -&!2 8 
 16, pp. 29-32, May, 1973.  13. 
 E. Kalman and R. S. 
 The half -power points of the antenna  radiation pattern (i.e. the -3 dB beam width) are  normally specified as the limits of the antenna  beam width for the purpose of defining angular resolution; two identical targets at the same distance  are, therefor e, resolved in angle if they are separated by more than the antenna beam width. An  important remark has to be made immediately: the smaller the beam width Θ, the higher the  directivity of the radar antenna, the better the bearing resolution. 
  +1 
 SPHERIC PLASMA AND  HENCE  THE IONOSPHERE VIBRATES LOCALLY AT FREQUENCIES TYPICALLY IN THE RANGE OF  nn (Z  IMPOSING A CORRESPONDING MODULATION ON ANY TRANSITING  RADIOWAVES 3HIP ECHOES CAN BE OBSCURED BY THIS MODULATION u 4HE EQUATORIAL ELECTROJET  PART OF THE GLOBAL SYSTEM OF FIELDS AND CURRENTS DRIVEN BY THE DYNAMO ACTION OF WINDS  AND TIDES  IS HOST TO SMALL SCALE FIELD 
 BASED WAVE 
 PULSE RADAR FREQUENCY CHANGE  WHICH WILL ALTER THE PHASE RELATIONS BETWEEN THE ECHOES FROM DOMINANT REFLECTING SURFACES OF THE TARGET n 4HE FREQUENCY CHANGE MUST BE SUFFICIENT TO CAUSE ENOUGH CHANGE IN  RELATIVE PHASES OF THE REFLECTORS TO RESULT IN STATISTICALLY INDEPENDENT SAMPLES OF TARGET SCINTILLATION AT EACH NEW FREQUENCY !N APPROXIMATE RULE IS A MINIMUM FREQUENCY CHANGE OF  S  WHERE S IS THE RADAR RANGE DELAY TIME BETWEEN THE LEADING AND LAGGING  EXTREMITIES OF THE TARGET 4HE REDUCTION IN RMS ANGLE AND RANGE TARGET SCINTILLATION MAY BE APPROXIMATED BY DIVIDING BY THE SQUARE ROOT OF  N   WHERE N IS THE NUMBER OF  FREQUENCY STEPS PROVIDED 2EDUCTION OF )NTERNALLY #AUSED %RRORS  !NGLE ERRORS CAUSED BY RECEIVER THER 
 NOISE RATIO 31.2  OF AN IDEAL !$ CONVERTER IS GIVEN BY   31.2D"    .       0RACTICAL !$ CONVERTERS HAVE ADDITIONAL SAMPLING ERRORS OTHER THAN QUANTIZATION   INCLUDING THERMAL NOISE AND APERTURE JITTER 0ROVIDED THAT THESE ADDITIONAL ERRORS CAN  BE CHARACTERIZED AS WHITE  THEY CAN BE COMBINED WITH THE QUANTIZATION NOISE WITH A RESULTING 3.2 LESS THAN THE THEORETICAL 3.2 OF THE IDEAL CONVERTER "ECAUSE VARIOUS !$ CONVERTER ERROR MECHANISMS ARE DEPENDENT ON INPUT SIGNAL LEVEL AND FREQUENCY  IT IS IMPORTANT TO CHARACTERIZE DEVICES OVER THE FULL RANGE OF INPUT CONDITIONS TO BE EXPECTED 4HE AVAILABLE SIGNAL 
 All the local oscillators are phase referenced to the same master  oscillator , which is also used to produce the transmitted waveform. The in-phase  (I)  and quadrature  (Q) components at baseband represent the real and imaginary parts,  respectively, of a complex number whose complex argument in phasor notation is the  phase difference between the transmitted and received pulses. The complex modulus,  or magnitude, is proportional to the received echo strength.FIGURE 4.7  Pulse doppler dwell timelineLook 2 Look 3 Look 1Beam PositionBarFrame PulsestimeCPI 1CPI 2CPI 3CPI 4 ch04.indd   10 12/20/07   4:52:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 02& CATEGORY IF THE OLDER DEFINITION OF HIGH 02& NO VELOCITY AMBI 
 ENCE WAVEFORM IS GENERATED WITH TIME DELAY  S 2  SWEPT BANDWIDTH  "2  PULSEWIDTH  42   AND ,&- SLOPE  @2 4HE REFERENCE WAVEFORM TIME DELAY IS TYPICALLY DERIVED BY RANGE  TRACKING OF A SELECTED TARGET WITHIN THE RANGE WINDOW 4HE CORRELATION MIXER  #-   IN &IGURE  PERFORMS A BANDPASS MULTIPLICATION OF THE RECEIVED SIGNAL BY THE OUTPUT OF THE REFERENCE WAVEFORM GENERATOR 4HE LOWER SIDEBAND AT THE #- OUTPUT IS SELECTED BY A BANDPASS FILTER "0&   3PECTRUM ANALYSIS IS PERFORMED WHEN THE ,&- SLOPES OF THE TRANSMIT AND REFERENCE  WAVEFORMS ARE EQUAL  @   @ 2  2EDUCED 
 POL (( (6   QUAD 
 Mavroides. and R. H. 
 Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 12.42  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 14. Y . 
 It was 9.1 m in diameter with a tolerance of 1.52 mm rms and a specific weight of 1.4 kg/m2.41'50 The ATS-6 antenna embod- ies the flex-rib technique. During the years subsequent to that launch, Lockheed has evolved flex-rib deployment technology to additional reflector designs, the poly conic and the maypole designs.41 Harris developed the radial-rib double-mesh design and in 1970 built a 12.5- ft-diameter antenna.40 This was followed by the TDRSS 4.88-m-diameter antenna and three generic antenna designs including the radial-rib, TRAC, and hoop- column concepts. The weight-versus-diameter capabilities of these three designs are shown in Fig. 
 • The aurorae are dynamic structures governed by fields and plasma flows in the mag - netosphere; strong electric fields aligned with the magnetic field accelerate electrons  down into the ionosphere where they produce highly ionized formations that reflect  radio waves very efficiently. The resulting doppler-spread echoes are so strong they  can incapacitate a radar through its sidelobes. • Geomagnetic storms and sub-storms result from solar flares and coronal mass ejec - tions. 
 Skolnik (ed.), McGraw-  Hill Book Co., New York, 1970.  10. Hill, J. 
 DEPENDENT WEIGHTING TO VOLTAGES COLLECTED OVER MUL 
 Systems Teclmolog_v. (Plcssey Co. !ford. 
 1.4. InChaps. 9to14,inclusive, thedetailed design ofeach ofthe com- ponents shown inFig. 
 Devices that accomplish this  purpose are called CFAR.  A CFAR may be obtained by observing the noise or clutter background in the vicinity of  the target and adjusting the threshold in accordance with the measured background. Figure  10.11 illustrates the cell-averaging CFAR which utilizes a tapped dejjy-line :o sample the  range cells to either side of the range cell of interest, or test cell. 
 The range gating necessary to perform automatic tracking offers several advantages as by-  products. It isolates one target, excluding targets at other ranges. This permits the boxcar  generator to be employed. 
 Correlated errors are discussed  in Section 13.6. Analyses of the far-field effect of errors are based on the fact that antennas are  linear devices. That is, the far-field pattern is the sum of the voltage (amplitude and  phase) of each radiating element in the antenna. 
 Geosci. Remote Sens. 1992 ,30, 706–713. 
 A  significant reduction in data rate generally is not desirable. Dependence on burnthrough as a  major FCCM lactic is questionable. It should be used where cost-elTectivc and where the  reduction in data rate is tolerable. 
 Byappropriately adjusting itsparameters, theWeibull canbemadetoapproach eithertheRayleigh orthelog-normal distributions. TheRayleigh isactually amember oftheWeibullfamily,andresultswhen ex=2.Theexponential pdfisalsoamember oftheWeibull familywhen ex=1.(Further discussion oftheWeibull pdfisgiveninSec.13.5.) Aknowledge ofthestatistics oftheclutterisimportant inordertoproperly designa CFAR(constant false-alarm rate)receiver 115andtoavoidthelossassociated withareceiver detector designed onthebasisoftheimproper statistical modelofclutter. Theoryofseaclutter.Inthepast,attempts weremadetoexplair:themechanism ofseaclutter byreflection fromacorrugated surface, 16bybackscatter fromthedroplets ofspraythrownby thewindintotheairabovetheseasurface, 16.17orbybackscattering fromsmallfacets,or patches, ontheseasurface!8 Noneofthesemodelswereabletoexplain adequately the eAperimental observations. 
 16  False Alarm Rate  ................................ ................................ ................................ 
 Research radars explore the depolarization ratios by alternating horizontally  and vertically polarized pulses. However, the preferred configuration for opera - tional radars is to transmit both horizontal and vertical polarizations simultaneously  while independently receiving both orthogonal signals for polarimetric processing,  allowing reception of the important co-polar quantities. The relative phase of each  transmitted polarization is arbitrary, but the differential magnitude and phase of  the co-polar received signals in each polarization are sufficient for the polarimetric   measurements. 
 , vol. 14, pp. 1430–1436, 1975. 
 C. Miller and J. Gibbs, “Ionospheric analysis and ionospheric modeling,” AFCRL Tech. 
 The minimum range at which a target can be detected is determined largely by the pulse length. If a target is so close to the transmitter that theecho is returned to the receiver before the transmission stops, the reception. 16of the echo, obviously, will be masked by the transmitted pulse. 
 G. Bath, “Separated covariance filtering,” in Rec. IEEE 1990  International Radar Conference , 1990, pp. 
 l, pp. 70-65, July, 1964.  J6. 
 TATION THEY PROVIDE OF THE ELECTRONIC ENVIRONMENT ! RADAR WARNING RECEIVER 272  IN AN AIRBORNE INSTALLATION PROVIDES ALERTS OF THE PRESENCE OF THREATS SUCH AS RADAR ON A MISSILE  SUPPLYING THE RELATIVE BEARING ON A COCKPIT 
 Solid- state sources, unlike klystrons, have white FM noise at the higher frequencies.19 This noise folds down in the operation of a pulse doppler radar. The locked source method of measurement, mentioned on page 14.12, can be conveniently altered to measure the total folded noise. The servo is designed to remove noise from the phase detector in the correct proportion to account for the correlation effect. 
 49. Shefer, J., and R. J. 
 This technique, when cou - pled with “spotlighting” the radar antenna on the target, results in an increase of the  radar’s detection range. Spotlighting or burnthrough modes might be effective, but  a price must be paid. As the radar dwells in a particular direction, it is not looking  elsewhere—where it is supposed to look. 
 A. Farina and F. A. 
 ATMOSPHERICv FLIGHT   C  PROBABILITY THAT TARGET MOTION IS hENDO 
 DOPPLER SPACE  AND #&!2 TECHNIQUES CAN POTENTIALLY BE USED TO LOWER THESE UNWANTED SIGNALS BENEATH THE DETECTION THRESHOLD  ONCE AGAIN PREVENTING THE DETEC 
 £n°£ä  2!$!2 (!.$"//+  OFFERED AN ADVANTAGE WHEN ATTEMPTING TO DISTINGUISH NEW ICE FROM CALM SEA AT # BAND  AND MODERATE INCIDENCE 4HE APPLICATIONS DIVERSITY IMPLIED A SPAN OF PREFERRED INCI 
 Any use is subject to the Terms of Use as given at the website. Radar Cross Section.  RADAR CROSS SECTION  14.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 the reflection and shadow boundary directions. Michaeli later investigated the removal  of the singularities, the cleverest of which was the use of a skewed coordinate system  along the wedge surfaces.44,45 While these methods of evaluating the fields scattered by edge elements may be  applicable to smooth unbounded edges, they do not account for the discontinuities  at corners where the edges turn abruptly in other directions. 
 Chappell, and R. Batty: The Measured and Calculated RCS of a Resistive Target  Model, IEE (Lo11do11) Radar-77, pp. 120-124, Oct. 
 Extensive measurements at Ku band in the open ocean  tended to confirm this behavior.68 In measurements in natural rain over Chesapeake Bay, Hansen69 found that even  a light rain (2 mm/h) changes the spectral character of sea clutter at moderate wind  speeds (6 m/s) by introducing a significant high-frequency component. He also  found some evidence in support of the radar operators, at least for the low graz - ing angles and horizontal polarizations with which most shipboard radars operate.  Figure 15.16 compares the correlation function of sea clutter (X band, low grazing  angle, H polarization) with and without rain for a 15-kt wind speed and a rain rate  of 4 mm/h. 
 DELAY CANCELER . 
 rain clutter,  sea clutter from rough sea surfaces) and from signal processing devices (processing clutter).  For example, the range side -lobes from target echoes in pulse co mpression systems.    These types of clutter can be eliminated by appropriate CFAR ( C onstant False Alarm Rate)  methods. 
 The outer two antennas  provide accurate. but ambiguous, measurement of elevation angle. The function of the one or  tnore inner antennas is to resolve the ambiguities. 
 170-175, 1975. 5. Hartt, J. 
 COMPARISON MONOPULSE WITH SEPARATE APERTURES COMPARED WITH AMPLITUDE 
 16.12 MTI improvement factor / for DPCA compensation as a function of the fraction of the horizontal phase center sepa- ration W that the horizontal antenna aperture is displaced per interpulse period, VxTJW. W = 0.172a. A block diagram of the double-delay system is shown in Fig. 
 44. Valcn7.~la. G. 
 FIGURE 20.7  The frequency dependence of the RCS for an 11 m long by 1 m diameter, perfectly  conducting cylinder, presented for various illumination geometries. The E vector and the 11 m dimen - sion are in the same plane; 0 ° (nose-on), 45 °, and 90 ° (broadside) curves are shown. The top (dashed)  curve is for a resonant dipole at 90 °. 
 PULSE MEASUREMENTS ! GUARD BEAM WITH A NEAR 
 11," R. C. Hansen (ed.), Academic Press, N.Y., 1966, chap. 
  RADAR WITH A  
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 14.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 where most of the rays between the two reflectors converge. 
 M FAN MONOPOLE PAIRS GROUPED AS  OVERLAPPED SUBARRAYS LINEAR ARRAYS OF  TWIN MONOPOLE ELEMENTS ARRAYS AT n CONTIGUOUS LINEAR ARRAYS OF  r  M VERTICAL MONOPOLES WITH  M BACKSCREENS ARRAYS AT n,INEAR ARRAY OF  r  M  VERTICAL TWIN MONOPOLES9 
 36.Boyd.C.R.,Jr.:ADual-Mode Latching Reciprocal FerritePhaseShifter, IEEETrt.m\., vol.MTT-18, pp.1119-1124, December, 1970. 37.Boyd,CR.,Jr.:Comments ontheDesignandManufacture ofDual-Mode Reciprocal Latching FerritePhaseShifters,JEEETram.,vol.MTT-22, pp.593-60I,June,1974. 3H.Fox,G.A.,S.E.Miller,andM.T.Weiss:Behavior andApplication ofFerrites intheMicrowave Region,BellSystemTech.J.,vol.34,pp.5-103,January, 1955. 
 12. Shen, D.; Zhang, J.; Yang, J.; Feng, D.; Li, J. SAR and optical image registration based on edge features. 
 DOMAIN RETURNS 4HE FREQUENCY INTERVAL BETWEEN SUCCESSIVE RETURNS IS  $F   4  AND THE OVERALL FRE 
 TheRotating<oil Method. —Figure 13.44 illustrates the circuits used toproduce the sweeps ofarotating-coil PPI, omitting such accessory parts asrange-marker circuits, etc. The tubes Vl,V*, Vu,and V4con- stitute asquare-wave and asawtooth generator similar tothose ofFig. 
 %3,  AND IS A USER 
 TRANSFORM PROPERTY REQUIRES THEIR &OURIER COMPONENTS TO OCCUR IN CONJUGATE  PAIRS  SO THAT IF THERE IS A COMPONENT  ! E JO  FT AT FREQUENCY  F WITH COMPLEX AMPLITUDE  !  THERE IS ALSO A COMPONENT  !  E 
 The negative pulse ontheplate ofVlbpasses back toV,.and retriggers ittoproduce asecond pulse delayed by2psec (Waveforms A and B). The cumulative effect ofthetwo actions charges Clsufficiently tocut offVlaforatime sothat further regeneration does nottake place. The first pulse isdriven down the4-psec delay line by~lb and triggers V2~ after atotal delay of6~sec. 
 DESIGNED TRACKING RADARS 4HESE INCLUDE CHANGES IN RELATIVE PHASE  AND AMPLITUDE BETWEEN MONOPULSE RECEIVER CHANNELS AS A FUNCTION OF SIGNAL STRENGTH  .   42!#+).' 2!$!2   °{Î 2& FREQUENCY  DETUNING  AND TEMPERATURE !LSO  PEDESTAL BENDING FROM SOLAR HEATING   NONORTHOGONALITY OF PEDESTAL AXES  GEARING BACKLASH  BEARING WOBBLE  GRANULARITY OF DATA READOUT  AND MANY OTHER FACTORS CONTRIBUTE TO ERRORS 4ABLE  LISTS THE MAGNITUDE OF THESE ERRORS FOR THE PRECISION INSTRUMENTATION RADAR !.&03 
 W.: Surface Acoustic Wave Devices-Technology and Applications, IEEE 1976 WESCON  Prc~fessional Program, Los Angeles, Sept. 14- 17, 1976, paper 2411.  23. 
 In Fig. 7.3 the gains of both patterns are normalized. However, the  maximum gain of the pattern resulting from the cosine distribution is 0.9 dB less than the gain  of a uniform distribution. 
 Radar System Engineering  Chapter 12 – Selected Radar Applications  151     The dynamic of the values can become somewhat compressed by the far field conditions.   13.3.7  Power Budget   Following i s given a large estimation of the power budget.  Also considered is the processing  gain by integration or pulse compression, as well as losses. 
 RANGE CHARACTERISTICS 0ARTIAL IMPLEMENTATION IS POSSIBLE BY DIGITIZING AT SUB 
 (When the target cross section fluctuates, the  28INTRODUCTION TORADAR SYSTEMS ,.",. ..n1Dr-CI)2~ I I I I I I I IQQQQQQQQ 0.9999 0.20.t0.80 20 18 8 10 12 14 16 (SIN),,signal-to-noise ratio,dB6/ I IIIIrl///IIIIII'IIII'1 /II///1///Il / I/III1//11 II1// //'III / I ////1'// I~/I,'III!VI ////II//~II//~Villi /II///If/// /1/I~IIIIfll //IIIIIIIVI //I I/IIIII // IIIIJ/ /II 10-3IIIIIvi//jY/,//~!j/ Probability of 10-41O-~, 1 i\ falsealarm -I10-610iIO-S 'O-10;1~0~-112../' I0.10 0.05 40.995 0.99 0.98 0.60 0.50 0.40 0.300.9995 0.999 0.998 g0.95 +­u W+- ~0.90 :0o.g0.70 L-a......o Figure2.7Probability ofdetection forasinewaveinnoiseasafunction ofthesignal-to-noise (power) ratioandtheprobability offalsealarm. Boththefalse-alarm timeandthedetection probability arespecified bythesystemrequire­ ments.Theradardesigner computes theprobability ofthefalsealarmandfromFig.2.7 determines thesignal-to-noise ratio.Thisisthesignal-to-noise ratiothatisusedintheequa­ tionforminimum detectable signal[Eq.(2.6)].Thesignal-to-noise ratiosofFig.2.7applytoa singleradarpulse.Forexample, supposethatthedesiredfalse-alarm timewas15minandtht: IFbandwidth was1MHz.Thisgivesafalse-alarm probability of1.11x10-9.Figure2.7 indicates thatasignal-to-noise ratioof13.1dBisrequired toyielda0.50probability of detection, 14.7dBfor0.90,and16.5dBfor0.999. 
 Table 1.2 lists the equipment indicator letters. Following the three letters are a dash and a numeral. The numeral is assigned in sequence for that particular combination of letters. 
 Summing the vector contributions  from all elements, with element 0 as phase reference, gives  E Neaj n s nn N ( )( / ) s inqq= == − ∑12 01 π λ   The factor 1 /N shows that each element is energized with 1/ N of the (unity) input  power. Normalizing the gain to unity at broadside, q  = 0, gives the pattern  EN s N sa( )sin[ ( ) sin ] sin [( ) sin ]qq q=π λ π λ/ / (13.2) Ea(q ) gives the radiation pattern for isotropic radiators and is known as the array  factor . It is shown in Figure 13.6 for N = 10. 
 Frequenq. TheplotoraOvs.grazingangleforvariousfrequencies (Fig.13.3)indicates that thclo\':crthcfrcqlIcncy.tilelesstheseacIu!ler.Thisappliesatthelowergrazinganglesand withhorizontal polarization. Thus,toreduceclutter,theradarshouldbeatalowfrequency. 
 MIMO radar topology: A systematic approach to the placement of the antennas. In Proceedings of the 2011 International Conference on IEEE Electromagnetics in Advanced Applications (ICEAA), Torino, Italy, 12–16 September 2011; pp. 114–117. 
 E., and J.-C. Sureau: Control of Radar Site Environment by Use of Fences. I£££ Trans. 
 H. Hibbs: An Organ Pipe Scanner, IRE Trans., no. PGAP-1,  pp 1 13 - 122, February, 1952. 
 Reduced by ripple loss versus range.No SNR loss. Reduced by ripple loss versus range.Reduced by weighting.Reduced by weighting and by ripple loss versus range.SNR 1. Limited use. 
 Thelatterstatesthattheposition andthevelocityof anelectron orotheratomicparticles cannotbesimultaneously determined toanydegreeof accuracy desired.Precisedetermination ofoneparameter canbehadonlyattheexpenseofthe other.Thisisnotsoinradar.Bothposition (rangeortimedelay)andvelocity (doppler frequency) mayintheorybedetermined simultaneously ifthePIXproduct and/orthe E/N0ratioaresurficiently large.Thetwouncertainty principles applytodifferent phenomena, andtheradarprinciple basedonclassical concepts shoulcf'not beconfused withthephysics principle thatdescribes quantum-mechanical effects.Inclassical radarthereisnotheoretical limittotheminimum valueofthe(jTR1>fproduct sincetheradarsystemsdesigner isfreeto chooseaslargeaPIXproduct (byproperselection ofthewaveform) andE/Noratioashe desires,orcanafford.Hislimitsarepractical ones,suchaspowerlimitations ortheinability to meettolerances. Inthequantum-mechanical case,ontheotherhand,theobserver doesnot havecontroliover hissystemasdoestheradardesigner sincethePIXproductofaquantum particleisfixedbynatureandnotbytheobserver. Angular accuracy. 
 4.9a. The output of the two single-delay­ line cancelers in cascade is the square of that from a single canceler. Thus the frequency  response is 4 sin2 nfd T. 
 A high range resolution profile on a single  target can allow recognition, assuming the target attitude is known or has been  guessed. Length, width, and location of major scattering features can be projected  into a range profile if the attitude is known. The number of types of major civilian  and military aircraft and ships is at most a few thousand, easily storable in memory. 
 ELEVATION $%,   ARE FORMED TO PROVIDE PHASE MONOPULSE AZIMUTH AND ELEVATION ANGLE  MEASUREMENTS 3ELF 
 MAKING OPERATOR.   %,%#42/.)# #/5.4%2 
 In the frequency-modulated CW radar (abbreviated  FM-CW), the transmitter frequency is changed as a function of time in a known manner.  Assume that the transmitter frequency increases linearly with time, as shown by the solid line  in Fig. 3.10~. 
 68. Pilon, R. 0., and C. 
 —Special problems areinvolved inproducing rapidly changing deflection currents such asthose involved inrange sweeps, since thevoltage across thecoil may become very large. For alinearly increasing current (asinarange sweep) this voltage is given by di di ‘z+ Ri=La+ Rat’ where aisaconstant. Since di/dtisalso aconstant thewaveform con- sists ofastep plus alinear increase. 
 Half the correction is added to one pulse and half subtracted  from the other, so that  Correction signal= =∑ =∆G Td dp2 2 2 2( ) ( ) θ θ θ θ θ θ θθ θTd dp∑∑( )( )  (3.18) where Σ2(q ) was substituted for G2(q ). The radar transmits a sum pattern Σ(q ) and  receives on the difference pattern ∆(q ), so that the received signal is proportional to  the product of the two. If the signal received on the difference pattern is used as the  correction, we have  Ec = ∆(q )Σ(q ) (3.19) By comparing Eqs. 
 ACTERISTICS WILL FIRST CONSIDER SIMPLE TARGETS  OF WHICH THE SPHERE IS A CLASSIC EXAMPLE 4HIS WILL BE FOLLOWED BY COMPLEX OBJECTS  OF WHICH AN AIRCRAFT IS A GOOD EXAMPLE 3IMPLE /BJECTS  "ECAUSE OF ITS PURE RADIAL SYMMETRY  THE PERFECTLY CONDUCTING  SPHERE IS THE SIMPLEST OF ALL THREE 
 Torrey, H. C., and C. A. 
 TOR WOULD HAVE TO BE REDUCED TO BRING THE JUNCTION TEMPERATURE DOWN TO AN ACCEPTABLE LEVEL $E 
 Making the same substitution of Eq. (14.29) into  the surveillance radar equation, L:q. (2.57), gives  R 2 = ~'~~i({i_l<!_ !! __!!j__  max (S/N)1 QPrjGi (14.31)  For jamming which enters via the antenna sidelobes rather than via the main beam, the  right-hand side of the above surveillance radar equation would be multiplied by the ratio of  maximum antenna gain to the gain of the si<lelobe in the direction of the jammer. 
 C-w Methods.—A method ofaccomplishing this byuse ofc-w signals isillustrated inFig. 17.6. Separate subcarriers fland f,arerespectively modulated bythe phase-shifted sinusoid and bythe reference signal, which isthesame sinusoid without phase shift. 
 Mumford: Some results of a Study of Ultra-short-wave  Transmission Phenomena, Proc. IRE, vol. 21, pp. 
 Weil. T. i\.: Survey of Raytheon Pulsed Radar Transmitters. 
 Thus, distances on the tube face along this rangesweeportimebaseare proportional to increments ofslant range. The scale Jactorrelates distances onthe tube toactual range, and the sweeplengthisthe distance represented; both are determined byspeed ofthe sweep. The origin ofrange may beonoroffthetube face; sometimes thestart ofthesweep isdelayed for some time after theinstant oftransmission oftheoutgoing pulse. 
 HALF OF THE PROCESSING BANDWIDTH  " 4T"P$    OR   $T4" "" "4PP      .   05,3% #/-02%33)/. 2!$!2   n°Îx 4HE RANGE WINDOW WIDTH IS    $RC4" "C" "4PP         3TRET CH 0ULSE #OMPRESSION 2ADAR %XAMPLES  4HIS SECTION DESCRIBES THREE  EXAMPLES OF RADARS THAT EMPLOY STRETCH PULSE COMPRESSION SYSTEMS  ,ONG 2ANGE )MAGING 2ADAR  4HE ,ONG 2ANGE )MAGING 2ADAR ,2)2  IS AN  8 
 Another method of processing the range or height information from an altimeter so as to  reduce the noise output from the receiver and improve the sensitivity uses a narrow-bandwidth  low-frequency amplifier with a feedback loop to maintain the beat frequency c~nstant.~'.'~  When a fixed-frequency excursion (or deviation) is used, as in the usual altimeter, the beat  frequency can vary over a considerable range of values. The low-frequency-amplifier band- 1  width must be sufficiently wide to encompass the expected range of beat frequencies. Since tlie  bandwidth is broader than need be to pass the signal energy, the signal-to-noise ratio 1s  reduced and the receiver sensitivity degraded. 
 As a result, the common discrete power increases by 3 dB. Table 4.7 provides the calculation for the system requirements for independent  and common discrete levels. As in Table 4.5, a maximum clutter level requiring a  12-bit A/D is assumed and the rms thermal-noise level at the A/D converter is set  to 1.414 quanta. 
 TO 
 An orange filter placed across the face of the tube eliminates the flash and  leaves only the long-persistent trace. If a blue filter were used instead, the afterglow of  the second layer wouid be removed, leaving only the short-duration flash. Thus a single  cascade screen can give either a short or a long persistence display, depending upon the filter  employed. 
 In a DBF system, adaptive  beamforming is accomplished either with the use of subarray receivers or with aux - iliary receivers. If subarray receivers are used, the number of nulls that can be placed  in the antenna pattern depends upon the number of degrees of freedom (DOF). For  adaptive beamforming, the number of degrees of freedom is N − 1, where N is the num - ber of receivers in the DBF array.100 If adaptive beamforming is implemented using  digital beamforming, element-level DBF will have significantly better performance  than subarray-level DBF, because subarray-level DBF has far fewer degrees of free - dom. 
 $IGITAL COHERENT SIGNAL PROCESSING GREATLY ALLEVIATES THE EFFECTS OF CLUTTER AND CHAFF   4HIS IS MOTIVATED BY THE USE OF COHERENT DOPPLER PROCESSING TECHNIQUES SUCH AS FIXED  ADAPTIVE -4)  OR OPTIMUM PULSE 
 V . J. Pisacane, Fundamentals of Space Systems , 2nd Ed, Oxford: Oxford University Press, 2005. 
 The effect of noise is to perturb the shape of the pulse and to  shift the time of threshold crossing as shown by the dashed curve. The maximum slope (rate of  rise) of the leading edge of a rectangular pulse of amplitude A at the output of a video filter is  -- --, II '11  / h' ---- \ Rectangular pulse  Tl (t ) --'-J,  I  ---------_J l  6T, -~ f.-R I  I ---, I ...... __ ,,  -I ~ise -i lime  = lr '.~"Rectangular"pulse  ' plus noise \  A \ Threshold -------.....\-------- \  \  \  " ' ' .............. 
 In the general dual-reflector case, blockage can be eliminated by offsetting both the feed and the subreflector (Fig. 3.2Ic). With blockage and supporting struts and spillover virtually eliminated, this is a candidate for very low sidelobes.32 It can be used in conjunction with an extended feed to provide mul- tiple or steerable beams.33(a) (b)PLANE WAVEFRONT PARABOLICREFLECTOR FEEDVIRTUAL FOCALPOINT . 
 6 of "Avionics Navigation Systems," M. Kayton and W.R.  Fried (eds.). 
 The complex envelope  of sr(t) is   u t A e u t t er rj f t dj f t td d d ( ) ( )( )= −− − 2 20π π  (8.41) The term u(t – td) is the complex envelope of the transmit waveform delayed in time  by td. The complex exponential exp[ j2p  fd(t – td)] represents a linear phase modulation  versus time that is impressed on the received echo signal by the doppler shift fd. The  carrier phase shift is qc = –2p  f0td. 
 CODED INTENSITY PLOT OR A PSEUDO 
 Radar cross section measurements using near-ﬁeld radar imaging. IEEE T rans. Instrum. 
 TOR  - 
 There will be still the need for scientists, RF,  microwave, digital and software eng ineers.  Also required will be antennas, microwave semico n- ductors, digital hardware and software, and last but not least, platform d evelopment.    . 
 Theseare unavoidable withobservations offiniteduration inthepresence ofnoise.Onekindoferroris tomistakenoiseforsignalwhenonlynoiseispresent.Thisoccurswhenever thenoiseislarge enoughtoexceedthethreshold level.Instatistical detection theoryitissometimes calleda typeIerror.Theradarengineer wouldcallitafalsealarm.AtypeIIerrorisoneinwhichthe signaliserroneously considered tobenoisewhensignalisactually present.Thisisamissed detection totheradarengineer. Thesettingofthethreshold represents acompromise between thesetwotypesoferrors.Arelatively largethreshold willreducetheprobability ofafalse alarm,buttherewillbemoremisseddetections. Thenatureoftheradarapplication will influence toalargeextenttherelativeimportance ofthesetwoerrorsand,therefore, thesetting ofthethreshold. 
 and Remote  Sensing , vol. 29, pp. 29–41, 1991. 
 Complex Scans.—A radar having spiral scan was used insingle- seat nightfighter aircraft during World War II. This complex scan may bedescribed asaconical scan inwhich theangular diameter ofthecircle described bythebeam iscontinuously varied from 0°toamaximum of, forexample, 60°and back toOO. Bythis motion thesolid angle covered isscanned completely in,say, 1secasthe beam spirals out\vard. 
 Step 3: Two images of each sub-aperture are performed with interferometric processing to obtain projection coordinates of the scattering points along the baseline. Step 4: 3-D images of each sub-aperture target are constructed by synthesizing the 2-D ISAR images of the interferometric processing results. Step 5: 3-D images of all sub-apertures are processed synthetically to obtain the ﬁnal 3-D images. 
 AES-6, pp. 620-628, September, 1970.  62. 
 24, 1977. 24. Luders, R. 
 RANGE CONTOURS ARE THE INTERSECTIONS OF CONCENTRIC SPHERES WITH THE GROUNDA SET  OF CONCENTRIC CIRCLES WITH THE SUBRADAR POINT AT THE CENTER &IGURE  B  4HE CONTOURS  OF CONSTANT ,/3 VELOCITY CALLED  ISODOPS  CORRESPOND TO THE INTERSECTIONS BETWEEN THE  SET OF CONES AND THE FLAT GROUNDA SET OF NESTED HYPERBOLAS &IGURE  C  &IGURE D  SHOWS THE COMBINATION OF CONSTANT 
    
 43. L. K. 
 R.: "Scattering and OilTraction of Radio Waves," Pergamon Press, New York, 1955.  16. King. 
 Lucas, G. Pinson, and R. Pilon, “Some results of RADARC-2 equatorial spread doppler clutter  predictions,” Proc. 
 Since the gain of the RF  amplifier is usually high compared to the reduction in receiver noise-figure, the net result is a  reduction in receiver dynamic range. However, this can be corrected and the original dynamic  range recovered by reducing the gain of the IF amplifier to maintain a constant output (or  constant noise level going into the display).54 On the other hand, if the mixer rather than the  IF amplifier is what limits the total dynamic range of the receiver, the introduction of the  low-noise front-end will cause a sacrifice in the mixer dynamic range and, consequently,  the dynamic range of the entire receiver.7  A low-noise receiver may also not be warranted if the RF losses preceding the receiver are  high. From Eq. 
 TER SEQUENCE FOR A SCANNING RADAR WITH  .    HITS PER BEAMWIDTH 4HIS LINEAR CLUTTER  SEQUENCE IS  CONSECUTIVE COMPLEX VOLTAGE RETURNS FROM ONE RANGE CELL OF DISTRIBUTED CLUTTER &IGURE  SHOWS THE PHASE AND AMPLITUDE OF THIS SEQUENCE )F THIS CLUTTER SEQUENCE WERE  D" STRONGER AND PASSED THROUGH A  6 )& LIMITER   ONLY THE PHASE INFORMATION WOULD REMAIN %ACH PULSE WOULD HAVE A  6 AMPLITUDE 7HEN THE RESULTING LIMITED CLUTTER SEQUENCE IS PASSED THROUGH A THREE 
 Type Bindication only isprovided; provision is. 200 THEGATHERING ANDPRESENTATION OFRADAR DATA [SEC. 6.13 made forexpansion ofthesector dead ahead when homing isbeing carried out. 
 Figure 13.43 illustrates anexample inwhich both thecenter ofthesector and thescale factor ineach direction can bechosen atwill. “Ineach diagram the top row comprises the azimuth sweep circuits. Anaudio oscillator VIexcites thefirst ofapair ofdifferentially connected synchros byusing itsrotor inanoscillating circuit. 
 7. J. C. 
 This linear FM will be offset in frequency by a^Ar. With the range-doppler coupling of the linear-FM waveform, the appar- ent range of this target will be Tapp = ~ ORbTI(Oin ~ CLR) This results in a time-expansion factor ofoR/(oin - aR) for the compressed pulse. Again the range coverage capability of the system depends on the processing bandwidth that can be implemented. 
 Extracting the aspect entropy from pixels can help us analyze the scattering characteristics for the structure of a target and offer an overview of full-scene anisotropy. At the application level, targets are usually the object of analysis. Therefore, we propose the aspect entropy extraction method at the target level based on the aspect entropy of the pixels. 
 DIS 
 I\ tr1111s11011d!'I' repeater plays hack a stored replica of the radar signal after it is triggered  by the radar. The transmitted signal is made to resemble the radar signal as closely as  practicable. The transponder might also radiate a noise pulse. 
 PHASE PROGRESSION ACROSS  THE APERTURE WILL SCAN THE BEAM BY   $$PP  F FCOSRAD  &OR  ONE DIRECTION OF SCANNING  THIS EFFECT WILL ADD TO THE APERTURE EFFECT FOR THE  OPPOSITE DIRECTION  IT WILL TEND TO CANCEL THE APERTURE EFFECT )N A WAVEGUIDE  WITH THE  GUIDE WAVELENGTH DENOTED  K G  THE EFFECT IS MORE PRONOUNCED AND THE RESULTANT CHANGE  IN BEAM POSITION IS   $$PP  L LGF FCOSRAD  7HEN  ANALYZING AN END 
 19D. London. pr. 
 If this error cannot betolerated, thevideo signals must bepassed through a 6-psec delay line before they reach theindicators. Figure 17.3 also illustrates one method for excluding allsignals except during aninterval surrounding theexpected time ofarrival ofthe desired signal. The coincidence pulse from theplate ofViispassed, after buffering inVw,through a2-Asec delay line, and isused totrigger the flip-flop circuit formed by V* and V6b (Sec. 
 Radant, D. Lewis, and S. Iglehart, “Radar sensors,” UCLA Short Course Notes, July 1973. 
 Since antenna heights were different, FT, FR, L7, and LR are ex- pected to be different but were not measured. In all cases the measured bistatic to monostatic ratios were less than unity. In two cases they ranged from -2 dB to -12 dB, and in the third case they dropped from 5 dB at (3 = 23° to -20 to -25 dB at p = 60°. 
 Asmallsubreflector reducesaperture blocking, butit hastohesupported atagreaterdistance fromthemainreflector. Thegeometry oftheCassegrain antenna isespecially attractive formonopulse tracking radarsincetheRFplumbing canbeplacedbehindthereflector toavoidblocking ofthe aperture. Also,thelongrunsoftransmission lineouttothefeedatthefocusofaconventional parabolid areavoided.. 
 Sensors 2019 ,19, 3344 The time delays tg(p)for p-th main pulse and l-th microburst are arranged in ascending order, i.e., g=0, 1, 2, 3,...,G-1, where Gis the full number of asteroid’s generic points, g=0 is the index of the minimum time delay from the nearest generic point, i.e., t0(p)= tg,min(p),g=G-1 is the index of the maximum time delay from the furthest generic point, i.e., tG−1(p)= tg,max(p). For the p-th main pulse and l-th microburst in the sequence of pulsar emissions the signal reemitted by g-th generic point limited by the microburst’s time width, T, can be rewritten as sr,g(t)= ag·rect⎭parenleftBiggt−Tpl−tg T⎭parenrightBigg ·exp⎡ ⎢⎢⎢⎢⎢⎢⎢⎣−2·⎭bracketleftBig t−T pl−tg⎭bracketrightBig2 T2⎤ ⎥⎥⎥⎥⎥⎥⎥⎦×exp⎭bracketleftBig j·2π·f r·(t−Tpl−tg)⎭bracketrightBig , (5) where rect⎭parenleftbiggt−Tpl−tg T⎭parenrightbigg =⎧⎪⎪⎨⎪⎪⎩1,if0≤t−Tpl−tg T<1 0, othewise. The following substitutions are made t=Tpl+tkp,tkp=tg,min(p)+ k.ΔT,ˆtg(p)= tkp−tg(p), where k=0,K+( kmax−kmin)−1is the current signal sample’s number in the microburst and /or the signal sample’s number measured on the range direction, K=int(T/(ΔT)is the full range signal samples’ number, kmax=int[tg,max/(ΔT)]is the index of the range bin where the signal reemitted by the furthest generic point with time delay tg,max is recorded, kmin=int[tg,min/(ΔT)]is the index of the range bin where the signal reemitted by the nearest generic point with time delay tg,minis recorded, the diﬀerence (kmax−kmin)denotes the relative object’s time width, measured on range direction. 
 Ref. 37, vol. II, pp. 
 Solid curve  3 D f XQ  LC  +- 0  0) represents transmitted signal; dashed  curve represents echo. (a) Linear fre-  quency modulation; (b) trianguJar fre-  m Time --+ quency modulation; (c) beat note of  (el tb).  82INTRODUCTION TORADAR SYSTEMS Rangeanddoppler measurement. 
 A typical implementation for the spectral analysis processing includes a second  frequency conversion following the CM to a final intermediate frequency (IF), anti- aliasing filtering, direct sampling at the final IF using an analog-to-digital converter  (ADC), digital down conversion (DDC) to a complex envelope sequence, time-domain  weighting, and spectral analysis using an FFT padded with zeros.64 Previous imple - mentations used analog product detectors to extract I and Q baseband signals, with  separate ADCs in the I and Q baseband channels. Correlation Mixer Output Signal Analysis.  The received signal at the CM input  port from a point target is  x t Atf f td in rectT( ) cos[ ( ) ( ) =−   + − +τπ τπα 20 ( ( ) ] t−τ2 (8.25) where A is the amplitude, T is the transmit pulsewidth, f0 is the carrier frequency, fd   is the doppler frequency, t is the signal time delay, and a is the LFM slope for the  transmit waveform. 
 III in Wellington XII Aircraft, C.C.D.U. Report No. 43/20, 18th May 1943 (TNA AIR 65/15). 
 15.15 MTI improvement factor as a function of the rms velocity spread of clutter for a four-pulse binomial-weight canceler. train of N identical pulses, is comparable with or larger than the reciprocal of anticipated target doppler shifts, the difference between a conventional white- noise matched filter (or coherent integrator) and a filter optimized to reject the accompanying clutter becomes significant. The characteristics of the clutter are characterized by the covariance matrix <bc of the N clutter returns. 
 xiv. List of abbreviations AC alternating current AGC automatic gain control AI airborne interceptorAMRE Air Ministry Research Establishment AP air publication ARI aircraft radio installationASuW anti-surface warfareASV air to surface vessel ASW anti-submarine warfare ASWDU Air Sea Warfare Development UnitBA beacon approach BABS beam approach beacon system c/s cycles per second (now Hz)CCDU Coastal Command Development Unit CHL chain home low CRT cathode ray tubeCTTO Central Tactical and Trials OrganisationCV common valve DC direct current DERA Defence Evaluation and Research AgencyDRA Defence Research Agency Dstl Defence Science and Technology Laboratory EMI Electrical and Musical IndustriesFAA Fleet Air Am FTC fast time constant GR ground reconnaissanceHF high frequency HQ headquarters HT high tensionIF intermediate frequencyIFF Identify Friend or Foe JASS Joint Anti-Submarine School kc/s kilocycles per second (now kHz)LL Leigh Light LO local oscillator LRASV long range ASVLT low tension MAPRE Ministry of Aircraft Production Research Establishment Mc/s megacycles per second (now MHz)Mk. MarkMU maintenance unit nmi nautical mile P d probability of detection Pfa probability of false alarm PPI plan position indicator pps pulses per secondPRF pulse repetition frequency xv. 
               
 Thus the angle errors can be  averaged by operating the radar over a wide frequency band or by sweeping the RF frequency  atid dcducilig tlie arigle on tllc basis of tlie correspotldirig behavior of the error It  turns out, however, that the bandwidth required to extract the target elevation angle is esesen-  tially the same required of a short pulse for separating the direct and reflected signals. Thus,  tlie hatidwidtlis r~ccdccl to elirnitiatc tlic rnultipath error are ilsually quite large for riiost  applications.  The doppler frequency shift of tlie direct signal differs from that of the surface-reflected  slgnal, but the difference is too small in most cases to be of use in reducing the errors due to  multipath. 
 TANCE THAT CAN GENERATE VERY HIGH VOLTAGE SPIKES AND CAUSE DAMAGE TO --)# POWER AMPLIFIERS )N ADDITION  THE DC POWER SOURCE MUST INCLUDE APPROPRIATE ENERGY STORAGE  SOMETIMES LOCALLY IN THE MODULE  IN ORDER TO SUPPORT THE MINIMUM VOLTAGE PULSE DROOP AS A FUNCTION OF TIME %NVIRONMENTAL 0ROTECTION #ONSIDERATIONS  --)# COMPONENTS UTILIZE THIN 
 ABLE DIGITAL SIGNAL PROCESSING  A NUMBER OF FUNCTIONS  SUCH AS  MONOPULSE COMPARISON   CURRENTLY PERFORMED IN THE DIGITAL DOMAIN  WERE PERFORMED USING ANALOG PROCESSING WITHIN THE RECEIVER 2EADERS INTERESTED IN THE DETAILS OF THESE ANALOG PROCESSING TECH 
 An example of a flat, two - dimensional target with an extension D  >> R*ΘH will be shown by Figure 3.2 on the basis of   geometric optics.     Figure 3.2  Reflection on a flat, extended target.   The mirrored reflection is in relation to a “virtual” sourc e from a distance R behind the target. 
 K. Barton, CW and Doppler  Radars,  Section VI-4, V ol. 7. 
 SYNCHRONOUS ORBIT  WHICH IS ONE THAT MAINTAINS A CONSTANT ANGLE OF ITS ORBIT PLANE RELATIVE TO SOLAR ILLUMINATION OVER THE ENTIRE YEAR 4HE %UROPEAN 3PACE !GENCYS %NVISAT SPACECRAFT IS A GOOD EXAMPLE OF A SUN 
 EFFECTIVE TO REDUCE THE DATA SAMPLE RATE TO A VALUE THAT IS JUST ADEQUATE TO SUPPORT THE BANDWIDTH OF THE SYSTEM )N APPLICATIONS WHERE THE SAMPLE RATE OF A SIGNAL IS TO BE DECREASED DECIMATED   THE FREQUENCY CONTENT OF THE SIGNAL MUST FIRST BE REDUCED SO THAT THE .YQUIST CRITERION IS SATISFIED FOR THE NEW SAMPLE RATE 4HIS CAN BE ACCOMPLISHED BY FIRST PASSING THE SIGNAL THROUGH A DIGITAL &)2 FILTER TO RESTRICT THE BANDWIDTH OF THE SIGNAL TO LESS THAN HALF OF THE DECIMATED SAMPLE RATE  AND THEN REDUCING THE SAMPLE RATE OF THE FILTERED SIGNAL BY A FACTOR OF  2 BY SELECTING EVERY  2 TH SAMPLE  AS DESCRIBED IN THE  PREVIOUS DISCUSSION OF DECIMATION ! DESIGNER CAN TAKE ADVANTAGE OF DECIMATION BY REALIZING THAT ONLY THE FILTER OUTPUTS THAT ARE USED NEED TO BE COMPUTED &OR EXAMPLE  IF THE OUTPUT OF A &)2 FILTER IS TO BE DECIMATED BY A FACTOR OF   ONLY EVERY FOURTH FILTER OUTPUT NEEDS TO BE COMPUTED  WHICH REDUCES THE REQUIRED PROCESSING BY A FACTOR OF  )NTERPOLATION &ILTERS  )NTERPOLATION IS THE PROCESS BY WHICH THE SAMPLE RATE OF A  SIGNAL IS INCREASED  FOR EXAMPLE IN PREPARING THE SIGNAL TO BE UPCONVERTED TO AN )&  AS SHOWN IN &IGURE  )NTERPOLATORS ARE TYPICALLY &)2 FILTERS WITH A LOWPASS FILTER RESPONSE 4O INCREASE THE SAMPLE RATE BY A FACTOR  2  2 n ZEROES ARE FIRST INSERTED  BETWEEN THE LOW 
 Second, theuseofabsorbing end cells costs 12db(6dbper end). The construction ofareflecting cellisshown in Fig. 16.34. 
 2ADAR 3ONAR .AVIG  VOL   NO   PP n  *UNE . Ó{°£ 
 CESSING 4HIS PROCEDURE IS KNOWN AS  MOTION COMPENSATION SOMETIMES ABBREVIATED  MOCOMP  &OR EXAMPLE  AT A PARTICULAR MOMENT  AS A PARTICULAR FREQUENCY IS TRANSMIT 
 PASS FILTERS IN A DETECTOR IS SHOWN IN THE FIGURE 4HE RECTANGULAR  2& SPECTRUM HAS BECOME  A TRIANGULAR VIDEO SPECTRUM 4HIS SPECTRUM DESCRIBES THE FADING OF THE DETECTOR OUTPUT FOR A #7 RADAR &OR A  PULSE RADAR  THE SPECTRUM IS SAMPLED BY THE PULSE REPETITION FREQUENCY 02&  )F THE 02& IS HIGH ENOUGH SO THAT THE ENTIRE SPECTRUM CAN BE REPRODUCED THE 02& IS HIGHER THAN THE .YQUIST FREQUENCY   $F D   THE DIAGRAM INDICATED IS THAT OF THE SPECTRUM OF THE  SAMPLES OF A RECEIVED PULSE AT A GIVEN RANGE &IGURE  SHOWS A SERIES OF ACTUAL PULSES FROM A MOVING RADAR  FOLLOWED BY A SERIES OF SAMPLES AT RANGE  2  4HE SPECTRUM  SHOWN IN &IGURE  IS THE SPECTRUM OF THE ENVELOPE OF SAMPLES AT  2 AFTER LOW 
 MTI RADAR  2.836x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 its third zero to the land clutter as the land clutter residue starts to dominate the output  of the first canceler. The zero locations of the optimum MTI are shown in Figure 2.88  and can be seen to move between the land clutter at zero doppler toward the doppler  of the chaff returns as the relative level of the land clutter becomes small. 2.15 RADAR CLUTTER MAPS In many MTI radar applications, the clutter-to-noise ratio in the receiver will exceed the  improvement factor limit of the system even when techniques such as sensitivity time  control (STC), improved radar resolution, and reduced antenna gain close to the horizon  are used to reduce the level of clutter returns. 
 The shift offrequency for both transmitter and receiver isautomatically almost exactly the same. Separate receivers and transmitters whose tuning controls have been ganged can beused ifdesired but this method requires more care indesign and installation. CODING The simplest type ofbeacon replies ~vith asingle pulse toevery pulse ofsufficient strength received within acertain band offrequency. 
 pp. 2000--2(X)I. December: 1966. 
 Soc., vol. 12, pp. 394-399, June 1961. 
 The realized system DESA, from the company Astrium GmbH, is shown in the Figures 13. 28  and 13.29.  It features the following specifications. 
 65. Mertens, L. E., and R. 
 R. K .. N. 
 TIME ADAPTIVE ARRAY PROCESSING 34!0   WHEREBY  A SET OF ANTENNA PATTERNS THAT DISPLACE THE PHASE CENTER OF THE ARRAY BOTH ALONG AND ORTHOGONAL TO THE ARRAY ARE CONTINUALLY SYNTHESIZED TO MAXIMIZE THE SIGNAL 
 An accurate measurement of radial velocity requires time. Hence  time is the basic parameter describing the quality of a radial velocity measurement. The  speed of a moving target and its direction of travel can be obtained from its track, which  can be found from the radar measurements of the target location over a period of time. 
 K., G. J. Burke, B. 
 2–6, February 2003. 117. A. 
 This in turn eliminates  the need to restrict the IF dynamic range, which can then be set to the maximum value  supported by the A/D converters. Thus, a system concept is obtained that provides  a clutter suppression capability that is limited only by the radar system stability, the  dynamic range of the receiver-processor, and the spectrum width of the returns from  clutter. The concept of a high-resolution digital clutter map to suppress clutter residues  is related to earlier efforts to construct analog area MTI systems using, for example,  storage tubes. 
 These, as well as other applications. have not been widely  employed because of the concomitant limitations tliat occur with operation at millimeter  waves.  l,in~itations of millimeter waves. 
 Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 19.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 Measurement Accuracy.  Because the received signals are sample functions  from gaussian random processes, the doppler spectrum and its moments cannot be  measured exactly in any finite period of time. 
 Shape Aspect Entropy Dihedral A 0.3823 Dihedral B 0.7131 Trihedral 0.7625 Top-hat 0.9999 3. Aspect Entropy Extraction In this section, aspect entropy extraction methods at the pixel level and the target level are proposed respectively. Since the smallest unit of a CSAR image is a pixel, it is convenient to obtain the RCS curve of a pixel by using the sub-aperture method. 
 of the IEEE , vol. 72, no. 8, August 1984. 
  RECEIVE BISTATICALLY SCATTERED ENERGY FROM THE SAME ILLUMINATED WEATHER VOLUME OVER A BROAD ANTENNA BEAM ! TRANSMITRECEIVE TUBE IS USED TO PROTECT THE RECEIVER  JUST AS IN A MONOSTATIC RADAR !LL GENERATED FREQUENCIES ARE LOCKED TO THE MASTER  
 DIMENSIONAL WEIGHTS AT A RATE LOWER THAN THE INPUT DATA AND APPLYING THEM TO THE RADAR SNAPSHOTS AT THEIR NATURAL RATE !N EFFI 
 Mueller, C., and P. Hildebrand: Evaluation of Meteorological Airborne Doppler Radar, Part H: Triple-Doppler Analysis of Air Motions, /. Atmos. 
 In heavy seas the sea return could extend out to several miles, dependent onthe sea conditions, and could saturate the PPI display. This would make detection of targets at close range dif ﬁcult and required careful manipulation of the gain control when homing on targets. For example, [ 13] reported that for ASV Mk. 
 RADARSAT-2 is an enhanced version19 of RADARSAT-1. Table 18.3 charts a sum - mary of its many modes.20FIGURE 18.2   RADARSAT-2 is outwardly similar to its predecessor. The  solar panels are parallel to the along-track axis of the antenna, indicative of  a dawn-dusk sun-synchronous orbit. 
 4.11. It is also  sometimes known as afeedforward filter, a nonrecursive filter, a.finite memory filter or a tapped  delay-line filter. The weights w1 for a three-pulse canceler utilizing two delay lines arranged as a  transversal filter are l, -2, 1. 
 LIMITED DISTRIBUTED CLUTTER  SEQUENCE .      AND A TARGET SUPERIMPOSED ON THE CLUTTER SEQUENCE  THE RESIDUE  SPIKES ARE DISTINCTLY DIFFERENT FROM THE TARGET RETURNS ! BINARY  - 
 LISH CURRENT FLOW IN THE SEMICONDUCTOR )T IS A CURRENT 
 HORN  SQUARE FEED IN ORDER TO PROVIDE GOOD OR EXCELLENT PERFORMANCE IN ALL DESIRED FEED CHAR 
 Hansen, V. G., and B. A. 
 6.8  L imiters / 6.29 6.9  I/Q Demodulators / 6.31 6.10  Analog-to-Digital Converters / 6.35 6.11  Digital Receivers / 6.40 6.12  Diplex Operation / 6.46 6.13  Waveform Generation and Upconversion / 6.47.     vii Chapter 7 Automatic Detection, Tracking, and Sensor Integration W. G. 
 QUALITY RADAR 
 CS-9, AD-A041316, June 1977. 111. E. 
 DRIFT VELOCITY OF ABOUT  OF  5 AND A FIXED  SCATTERER VELOCITY WHICH  APPEARS TO BE ABOUT  MS IN THE 8 
 The most basic model uses the radar range equation and enables an estimate of  received signal level, dynamic range, and probability of detection to be assessed. It  has significant weaknesses in that most close-range GPR systems are operating in the  near-field or even the reactive field of the antenna whereas the model assumes a far- field model. It is probably more relevant to the longer-range geophysical applications  where the target is many tens of meters from the radar. 
 SOURCE CASE OF ANGLE NOISE RESULTING FROM THE GEOMETRY AS DESCRIBED IN &IGURE   WHERE THE TARGET AND ITS IMAGE REFLECTED FROM A  &)'52%     'EOMETRY OF THE RADAR MULTIPATH  TRACKING CONDITION  WHERE THE REFLECTION FROM A  SURFACE APPEARS TO THE RADAR AS AN IMAGE BELOW THE SURFACE. °În  2!$!2 (!.$"//+  SURFACE TO THE RADAR BEAM ARE THE TWO SOURCES /VER A SMOOTH OCEAN SURFACE  THEY  ARE SEPARATED ONLY IN THE ELEVATION COORDINATE SO THAT MOST OF THE ERROR APPEARS IN THE ELEVATION 
 The width of the aperture in the z dimension  is tr, and tile angle in tile y,- plane as ~neasured from tlie y axis is 4. The far-field electric field  intensity, assuming (1 5> A, is  where A(:) = ci~rrent at distance ;, assumed to be nowing in .u direction. A(z), the aperture  distrihrrtiot~. 
 8. 218. Sensors 2019 ,19, 743 Figure 5. 
 TERFLY BECAUSE IT HAS TWO INPUTS &OR CERTAIN &&4 CONFIGURATIONS  RADIX 
 SPLITTING AND MAXIMUM 
 H. Cantrell, and F. D. 
 !XI\}\   IS SOMETIMES USED BECAUSE OF ITS EASE OF IMPLEMENTATION AND BECAUSE IT IS MORE ROBUST  )T SHOULD BE NOTED THAT THE #&!2 LOSS ASSOCIATED WITH A TWO 
 The results of the three methods are shown in Figure 2. Figure 2a is the result of BP , which is used as the referenced image. Compared with the result of the three method, the result of LS-CS-Residual remains less artifects as shown in the white circle. 
   -4) 2!$!2  Ó°nÎ ITS THIRD ZERO TO THE LAND CLUTTER AS THE LAND CLUTTER RESIDUE STARTS TO DOMINATE THE OUTPUT  OF THE FIRST CANCELER 4HE ZERO LOCATIONS OF THE OPTIMUM -4) ARE SHOWN IN &IGURE  AND CAN BE SEEN TO MOVE BETWEEN THE LAND CLUTTER AT ZERO DOPPLER TOWARD THE DOPPLER OF THE CHAFF RETURNS AS THE RELATIVE LEVEL OF THE LAND CLUTTER BECOMES SMALL Ó°£xÊ , ,Ê  1// 
 There are some problems, however, in the use of  solid-state devices for radar systems other than cost. 220 INTRODUCTION TO RADAR SYSTEMS  As mentioned, the solid-state transmitter has some significant differences as compared to  the conventional tube transmitter. The basic power-generating unit comes in a relatively small  size; hence, many units have to be combined_ in some manner to achieve the power levels  required for radar. 
 32. "Glossary of Meteorology," vol. 3, American Meteorological Society, Boston, 1959, p. 
 To this end the authors of this series make use of the  historical approach.  A torch lights the way i the: dark-.and assists us  through fog; it has for centuries been a symbol of  learning; as a traffic sign it warns us that we are coming  to a school. And, just as important, a torch spreads its  light on every one within its ambit, making no distinc-  tion between rich and poor or young and old. 
 PULSE -4) PROCESSOR WAS REPLACED BY THE SECOND 
 The total antenna temperature can be found by integrating the temperature "seen " by the  antenna, weighted by the antenna gain over the entire sphere.60  where dR = solid angle given by sin 0 d6 d4. The brightness temperature TB(O, 4) is often a  complicated function, and T, must be approximated by numerical means. The antenna tempera-  ture is an average value of the brightness, or space, temperature in the field of the antenna  pattern. 
 Effective aperture. Another useful antenna parameter related to the gain is the effective receiv­ ing aperture, or effective area. It may be regarded as a measure of the effective area presented . 
 NOISE FLOOR WITHIN THE RECEIVE PORTION OF )00 4HIS POWER LEVEL IS GIVEN IN DECIBELS WITH RESPECT TO THE CARRIER AMPLITUDE D"C  4HE THERMAL 
 17.25  17.5 Target Tracking  ......................................................  17.25  Single-Target Tracking  .......................................  17.25 Multiple-Target Tracking  .................................... 
 Thuswhenthesysteminstabilities arehigh,thedetection oftargetsincluttercanbeseriously degraded. Oneapproach foroperating undersuchconditions istousetwolimiters.39One limiterisplacedbeforethepulse-compression filterandhasanoutputdynamic rangeequalto thedifference between thepeaktransmitter powerandtransmitter noiseinthesystemband­ width.Theotherlimiterisbetween thepulse-compression filterandtheMTIandhasa dynamic rangeequaltotheexpected MTIimprovement factor. Thetechnology ofpulsecompression hasbeenappliedtoradarwithconventional, unmod­ ulatedpulsestoachieveCFAR(constant falsealarmrate)performance betterthanthatofthe log-FTC. 
 TION OF POSITIVELY AND NEGATIVELY CHARGED IONS RESULTING IN ELE CTRIC POLARIZATION 4HESE  MECHANISMS CAN BE ASSOCIATED WITH IONIC ATMOSPHERES SURROUNDING COLLOIDAL PARTICLES PARTICULARLY CLAY MINERALS   ABSORBED WATER  AND PORE EFFECTS  AS WELL AS INTERFACIAL PHENOMENON BETWEEN PARTICLES 4HE GENERAL FORM OF THE MODEL THAT DESCRIBES THE FREQUENCY DEPENDENCE OF SUCH  SYSTEMS IS THE $EBYE  RELAXATION EQUATION   ` 
 The position of Poker Flat ISR is shown as a red asterisk, while the observation area of each group is shown as a dashed rectangle in its corresponding color. From Figure 1, we can ﬁnd that Poker Flat ISR station is fully covered by PALSAR scenes of Group 2 and 3, while the range between the ISR station and PALSAR scene 1 is within 40 km. The PALSAR illumination modes of three scenes can also be observed in Figure 1. 
 € σ πr2=1 (11.17)  For Radar technology this is of interest, since this result corresponds to the definition of the  Radar cross- section.  Theoretically the sphere thus would be the ideal calibration standard for  Radar devices and Radar backscattering cross -sectional measurem ents.  That it is still seldom  used is due to the relatively low reflection capability compared to the physical size. 
 * *A ,OW 
 SIGMA  IS GIVEN BY ,EVANON   DF $  3.2    WHERE  3.2   SIGNAL 
 The last N zeros and ones are summed and compared with a second threshold T2 = M. For large N, the detection perfor- mance of this detector is approximately 2 dB less than the moving-window inte- grator because of the hard limiting of the data, and the angular estimation error is about 25 percent greater than the Cramer-Rao lower bound. Schwartz16 showed that within 0.2 dB the optimal value of M for maximum P0 is given by M = 1.5Vw (8.14) when 10~10 < Pfa < 10~5 and 0.5 <PD< 0.9. 
 SHAPED SPECTRUM FOR DIFFERENT IMPLEMENTATIONS OF THE FINITE 
 One-dimemional aperture distributiolL Perhaps thesimplest aperture distrihution toconceive istheuniform, orrectangular,distribution. Theuniform distribution isconstant overthe aperture extending from-a12to+a12andzerooutside. Forpresentpurposes itwillbe assumed thattheaperture extendsinonedimension only.Thismightrepresent thedistribution acrossalinesourceorthedistribution inoneplaneofarectangular aperture.Iftheconstant. 
 240INTRODUCTION TORADAR SYSTEMS maypermitenergytoleakthrough, withtheresultthatthebacklobewillincrease andIhe antenna gaindecrease. Solidsheetsurfaces maybeofeitheraluminum orsteel.15,16Steelisapopular choice, particularly whereweightisnotacontrolling factor.Itischeapandstrongbutisrelatively difficult toform.Stainless steelorplasticcoatedgalvanized steelareusedwhenthesurface mustberesistant tocorrosion. Aluminum islightinweightbutismoreexpensive thansteel. 
 TION OF HELICAL 474 AND SOLID 
 SIONS )N A SPHERICAL 
 Above 30 knots the increase is about  O. l dB/kn. Similar behavior is exhibited at 30° grazing angle. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar.  SYNTHETIC APERTURE RADAR  17 .96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 represent the distance from the mainlobe peak to the first null. 
 THE 
 Using a multiplicative factor α for linear processing or an additive factor β for  processing with a LOG -amplifier, the threshold value (TV) is calculated. Finally, the ampl i- tude of the signal under test (SUT) is compared with the threshold value to decide whether the  SUT belongs to a target or not.     The CAGO- CFAR has the advantages of requiring little processing power and having low  CFAR loss. 
 The output transducer taps a portion of this surface sound wave and converts it back into an electric signal. The SAW device7"9 has unique features that dictate its usefulness for a given radar application. The major shortcomings of the SAW approach are that the waveform length is restricted to under 200 JJLS by the physical size of available crystals and that each waveform requires another design. 
 SELECTABLE SCAN RATE    AZIMUTH ELECTRONI 
 5.1. Time-Frequency Grid Pulsar Signal Model For each frequency channel the pulsar signal model can be expressed as sr(t)=N−1⎭summationdisplay p=0L−1⎭summationdisplay l=0al·exp⎡ ⎢⎢⎢⎢⎢⎢⎢⎣−⎭bracketleftBig t−T pl⎭bracketrightBig2 2σ2p⎤ ⎥⎥⎥⎥⎥⎥⎥⎦·exp⎭bracketleftBig j·2π·f r·(t−Tpl)⎭bracketrightBig (3) 107. Sensors 2019 ,19, 3344 where fris the frequency of the r-th frequency channel, deﬁned by the expression fr= f0+r.Δf, where r=0,R−1is the frequency channel’s number, Ris the number of the frequency channels the signal is registered in, f0is the frequency of the 0-th channel, Δfis the diﬀerence between frequency channels (spectral resolution), alis the amplitude of the Gaussian microburst, σlis the time width of the l-th Gaussian microburst, l=0,L−1is the index of the Gaussian microburst, Lis the number of microbursts inside the main Pulse, pis the index of the main Pulse or the index of the Main Pulse’s repetition period, Tplis the composed repetition period deﬁned by Tpl=p·Tp+l·Tl, where Tpis the main pulse repetition period, Tiis the Gaussian microburst repetition period inside the main pulse, tis the current time, which in discrete form can be presented as t=Tpl+( k−1)·ΔT, where kis the time sample index inside the microburst, ΔTis the sample’s time duration inside the microburst. 
 l), which is  The noise No,, from the lossy RF components is kTo B,, and G = 1/&, . Therefore on substi-  tution into Eq. (9. 
 Trunk and J.D.  Wilson80 © IEEE 1987 ) ch07.indd   51 12/17/07   2:15:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 In addition to measuring the range to a target as well as its angular direc - tion, a radar can also find the relative velocity of a target either by determining the  rate of change of the range measurement with time or by extracting the radial velocity  from the doppler frequency shift of the echo signal. If the location of a moving target is  measured over a period of time, the track, or trajectory, of the target can be found from  which the absolute velocity of the target and its direction of travel can be determined  and a prediction can be made as to its future location. Properly designed radars can  determine the size and shape of a target and might even be able to recognize one type  or class of target from another. 
 Phase stability was also an issue. Since then  massive advances in digital signal correlation and processing, coupled with great  reductions in the cost of hardware to execute such processing, have mitigated these  problems. Many recent bistatic radar programs have demonstrated quite adequate  synchronization and stability—as well as detection performance—using off-the- shelf, commercial hardware. 
 408-409 l'nequally spacedarrays.331-332 Unfocused SAR.SIR519 tJniforll1 prohahility density function. 2122 Unigrid. 21U V-heamradar.542 Varactor diode.291 Variance. 
 1954.  31. Banks. 
 ING EVENTS  OR  SEA SPIKES  ISOLATED BY A SHORT 
 Figure 18.7 shows a summary history  of these factors. The data show that 2-cm instrument accuracy is the state-of-the-art  for conventional altimeters. The delay-doppler instrument (see below) would further  improve instrument precision64 to 1 cm. 
 Thus theRiekediagram givesthepoweroutputandthefrequency ofoscillation foranyspecified load condition. Although acartesian setofloadcoordinates couldbeused,itisusuallymore convenient toplotthepowerandfrequency onasetofloadcoordinates knownastheSmith chart.TheSmithchartisaformofcirclediagram widelyusedasanaidintransmission-line calculations, ApointontheSmithchartmaybeexpressed inconductance-susceptance co­ ordinates orbyasetofpolarcoordinates inwhichthevoltage-standing-wave ratio(VSWR) isplottedastheradius,andthephaseoftheVSWRisplottedastheangular coordinate. Thelatteristhemoreusualofthetwopossible coordinate systems sinceitiseasierforthe microwave engineer tomeasure theVSWRandtheposition ofthevoltage-standing-wave minimum (orphase)thanitistomeasure theconductance andsusceptance directly. 
 R. Vickers ) ch21.indd   39 12/17/07   2:51:50 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Security Conf. Rec ., Singapore, January 17–19, 1985. 15. 
 The useofabsorbing end cells is m [‘E;:;;’preferable with mercury lines of delay less than about 500 met. steelISctroWith longer lines, the useofreflect- @./ ingend cells may bebetter fortwo reasons. Inthe first place, attenu- ation always takes place within the v’ . 
 AVG ,OSS  LSD PY    C O S00! 2K 4 & 6R 4X 
 TRACKING GATE FROM THE TARGET POSITION THROUGH THE INTRODUCTION  OF A FALSE TARGET INTO THE RADARS RANGE 
 MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 the ship from the bow at 30 km and 6 ° grazing. The bright scatterers exhibit cross  range sidelobes, which can be partially reduced by sensing large returns, then apply - ing amplitude weighting and display compression, as has been done in this image.  Integration of multiple ISAR images dramatically improves quality . 
 It is also  possible to achieve a multicolor tube with variable persistence.  Although color displays may be pleasing and attractive to the operator, the applications  in which they have proven superior to properly coded monochromatic displays apparently  are fewer in number than might have been anticipated.'8  Bright displays. There are applications where it is not possible or convenient to use the  conventional CRT display that requires a darkened environment; such as in the cockpit of an  aircrart or an airfield control tower. 
 CALLY USED IN THE HIGH 
 ELEMENT ARRAY      
 VARYING WEIGHTS HAS NO APPRECIABLE EFFECT ON THE -4) VELOCITY RESPONSE CURVE 7HETHER  THE ADDED COMPLEX 
    
 However, the real value of mutual-support jamming  is in the coordinated tactics that can be employed. A favorite tactic employed against  tracking radars, for example, is to switch between jammers located on separate aircraft  within the radar’s beamwidth. This blinking has the effect of introducing artificial  glint into the radar tracking circuits, which, if introduced at the proper rate (typically  0.1 to 10 Hz), can cause the radar to break angle track. 
 PROCESSING TECHNIQUES $IGITAL SIGNAL PROCESSING OF THE RECEIVER OUTPUT ALLOWS THE DETECTION OF SIGNALS WELL BELOW THE RECEIVER NOISE FLOOR AND THE MINIMUM DETECT 
 72. D. 74. 
 (/) Stepped corner. azimuth and elevation beam width requirements are quite different, requiring the 44orange-peel," or oblong, type of reflector of Fig. 6.1b. 
 However, itisseldom, ifever,thattheoperational requirements donotpermitthesystemdesigner to configure asystemtodoanequivalent jobwithamechanically scanned antenna. AnN-element arraycan,inprinciple, generate Nindependent beams.However, inprac­ ticeitisseldomrequired thataradargenerate morethanafewsimullaneous beams(perhaps nomorethanadozen), sincethecomplexity ofthearrayradarincreases withincreasing numberofbeams. Although thearrayhasthepotential forradiating largepower,itisseldomthatanarrayis required toradiatemorepowerthancanberadiated byotherantenna typesortoutilizea totalpowerwhichcannotpossibly begenerated bycurrenthigh-power microwave tubetech­ nologythatfeedsasingletransmission line. 
 (21.19). The final term on the right-hand side of Eq. (21.37) is of the form Si" [(N + M (21.46)sin q where the quantity q is defined by 2*nx'vT ^1 _ q = "^T (2L47) The azimuth resolution factor, therefore, has a peak whenever the quantity q takes on a value equal to an integral multiple of TT rad. 
 Claims were made that a GPR had been  developed “that can provide three-dimensional images of objects up to 45.7 meters  below the surface of land and sea. Such a device would allow verifiers to identify  underground weapons facilities, like those of concern in Libya, Iraq, and North  Korea. The underwater detection capability could also be used to verify treaties  dealing with submarines and nuclear weapons positioned on the seabed.” How well  FIGURE 21.3  General system operation of GPR showing targets and sources of clutter ( Courtesy IEE ) ch21.indd   5 12/17/07   2:51:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 It also reduces the glint in a conical scan or a sequential-lobing radar, but the  TRACKING RADAR171 scatterers willchangeandanewresultant isobtained aswellasanewangular measurement. Measurements areindependent ifthefrequency ischanged byanamount36 c flfc=2D(5.3) (5.4)wherec=velocity ofpropagation andD=targetdepth.Theglinterrorcanbereduced by averaging theindependent measurements obtained withfrequency agility.(ThedepthDas seenbytheradarmightbelessthanthegeometrical measurement oftargetdepthifthe extremities ofthetargetresultinsmallbackscatter.) Theimprovement /inthetracking accuracy whenthefrequency ischanged pUlse-to-pulse isapproximately37 /2= 1 ~DBf'!. 2flfc/Bfa+2Bg/fp C whereBfa=thefrequency agilitybandwidth, D=targetdepth,c=velocityofpropagation, BI1=glintbandwidth, andI"=pulserepetition frequency. 
 The tube is housed in a  magnetically shielded package that stands approximately 2 ft high with a diameter of 1 ft and  weighs 210 lb. J\ Yac-lon vacuum pump is included within the magnetically shielded package  to monitor the vacuum and to provide continuous pumping action during operation. ln the  J\ N/M PS-36 transmitter chain the SFD-257 is preceded by an SFD-244 cathode-pulsed CF A  with 11 dB gain, which is driven by a 904Tl cathode-pulsed TWT with 49 dB gain. 
 Figure 10a shows the opposite of brightness variations along the eddy spiral, compared to Figure 1, since their radar look directions are opposite. ȱ Figure 10. Comparison of ( a) the simulated SAR eddy image and ( b) the ERS-2 SAR image under the same radar parameters and wind ﬁeld conditions. 
 DIMENSIONAL ARRAY )N THIS  FASHION  THE BEAM IS MORE EFFICIENTLY FORMED IN SPACE AND ONE AVOIDS THE LOSSES THAN CAN ACCUMULATE IN CORPORATE COMBINING 4HE TRANSMITRECEIVE 42  MODULE  REGARD 
 Like the locked coho, this tech- nique is not effective on second-time-around targets. Amplifier Chains: Special Considerations. The decision to use an amplifier chain, most often for coherence and agility, introduces many complications, some of which are noted here. 
 HAND EXPRESSION IS THE INCRE 
 M. Foster, “Directive diagrams of antenna arrays,” Bell System Tech. J ., vol. 
 F. Chen and A. K. 
 NUMBERED BEAMS  AND THE OTHER 230 STEPS ACROSS THE ODD 
 Skolnik, Introduction to Radar Systems , New York: McGraw-Hill Book Company, 1980,  p. 45. 22. 
 This error signal isamplified byapush-pull d-c amplifier and used to control the reflector voltage ofthe klystron insuch away that itsfre- quency isforced into agreement with theresonant frequency ofthecavity. l~ideo signals and pulses areapplied directly tothe reflector toproduce thedesired frequency modulation. Rapid response ispurposely avoided IR.V.Pound, AMicrowave Frequency Discriminator, RL Report No. 
 Therefore the ratio of the power incident on the target at B to that which  would he incident if the target were located in free space is  2 _ 2( _ 4Tt:lzah,) = 4 . 2 2Tt:lzah,  t7 -1 cos ).R sm ).R (12.4)  Because of reciprocity, the path from target to radar is the same as from radar to target. The  power ratio at the radar is therefore  4 _ 16 . 
 SWITCH MODULATOR CONTROLS BOTH THE BEGINNING AND END OF THE PULSE 3INCE THE ENERGY STORAGE DEVICE IS A CAPACITOR  THE PULSE CAN DROOP  SOMETHING THAT CAN BE PREVENTED BY EXTRACTING ONLY A SMALL FRACTION OF THE STORED ENERGY FROM THE CAPACITOR 4HIS REQUIRES A LARGE CAPACITANCE  WHICH MAY BE OBTAINED WITH A COLLECTION OF CAPACITORS CALLED A  CAPACITOR BANK 4HE ACTIVE 
 MIT Radiation Laboratory Series. McGraw- Hill Book Company. New York. 
 It is a good frequency for the obser - vation of weather because a lower frequency would produce a much weaker radar  echo signal from rain (since the radar echo from rain varies as the fourth power of  the frequency), and a higher frequency would produce attenuation of the signal as it  propagates through the rain and would not allow an accurate measurement of rainfall  rate. There are weather radars at higher frequencies, but these are usually of shorter  range than Nexrad and might be used for a more specific weather radar application  than the accurate meteorological measurements provided by Nexrad. C band (4.0 to 8.0 GHz). 
  AND  '(Z SIGNALS TO BE COMBINED INTO A SINGLE RADAR DISPLAY IN AN AUTOMATIC PROCESS  MAXIMIZING THE BENEFITS OF FREQUENCY DIVERSITY 3OME LARGE SHIPS HAVE AN ADDITIONAL  '(Z RADAR MOUNTED ON THE BOW AT DECK LEVEL 4HIS HAS TWO ADVANTAGES &IRST  THE VERTICAL LOBING WILL HAVE A DIFFERENT LOWER  ANGULAR FREQUENCY TO THE MAIN  HIGH 
 1), the gains are a compromise, increasing  to ( , ) ( ,( )) α β = −1 3 3. Because this model is a sampled continuous time acceleration,  it is preferred when update times are variable because the target does not maneuver  more or less when the update interval changes. The equations in Table 7.3 can then be used to calculate the filter performance in  terms of variance reduction ratios and tracking lags. 
 FIGURE 2.12 Comparison of gaussian, exponential, and polynomial spectra for an rms  spectral spread of sv = 0.25 m/s ch02.indd   13 12/20/07   1:43:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 I RE, vol. 46.  pp 1492 l~OI. 
 On land, clutter motion is usually due to moving vegetation, although moving animals and machines create similar effects. The radar return from an assembly of scatterers like those of Fig. 12.8 can change because of motion of the individual scatterers just as it changes because of motion of the radar. 
 Since the cross-correlation receiver and the matched-filter receiver are equivalent math­ ematically, the choice as to which one to use in a particular radar application is determined by  which is more practical to implement. The matched-filter receiver, or an approximation, has  been generally preferred in the vast majority of applications.  10.4 DETECTION CRITERIA .J  The detection of weak signals in the presence of noise is equivalent to deciding whether the  receiver output is due to noise alone or to signal-plus-noise. 
 ENT CAPABILITY TO COUNTER RETRO 
 Optical-feed monopulse arrays  include the lens array and reflectarray (Chapter 13) that are optically fed by a conven - tional monopulse feed. The AN/MPQ-3917 (Figure 9.1 b) is an example of an optically  fed array lens with the antenna mounted on a two-axis pedestal. Typical instantaneous  electronic angle coverage is ±45° to an almost ±60° cone field-of-view that may be  moved by pedestal drive to center on a multitarget event or follow an event progress - ing to a different area. 
 It is usually convenient to distinguish between two different regions when considering  radar propagation. One is the optical. or inte,ference, region, which is within the line of sight  (direct observation) of the radar. 
 14, pp. 56-61, May 1976. 47. 
 BEAM TUBE IS SIMILAR TO THE  KLYSTRON IN THAT THE CATHODE  2& CIRCUIT  AND COLLECTOR ARE ALL SEPARATE FROM ONE ANOTHER 4HERE IS  HOWEVER  CONTINUOUS INTERACTION OF THE ELECTRON BEAM  AND THE 2& FIELD OVER  THE ENTIRE LENGTH OF THE MICROWAVE PROPAGATING STRUCTURE OF THE 474 AS COMPARED TO THE KLYSTRON WHERE THE INTERACTION OCCURS ONLY AT THE GAPS O F A RELATIVELY FEW RESO 
 See also Airborne Moving Target Indication antenna sidelobes, 3.13 to 3.14 coverage, 3.2 to 3.3 platform motion, 3.3 to 3.14 TACCAR, 3.4 to 3.9 Airborne Moving Target Indication (AMTI) example of, 3.32 to 3.33 improvement factor, 3.8 multiple spectra, 3.31 to 3.32 scanning motion compensation, 3.14 to 3.17 and STAP, 3.23 to 3.31 Aircraft radar cross section, 14.13 to 14.14 Alpha-beta (/g302-/g533) filter, 7.26 to 7.27, 7.30 Altimeters, from space, 18.33 to 18.57 Altitude line, 4.4 to 4.5 A mbiguity function, 8.40 Ambiguity resolution, in MTI, 2.89 to 2.91 Amplitude-comparison monopulse, 9.3 to 9.11 Amplitude noise, in tracking, 9.27 to 9.30 AN/APG-76, 17.25 AN/APY-9, 3.32 to 3.33 AN/FPQ-6, 9.2, 9.9, 9.18, 9.21, 9.44 AN/FPS-23, 23.7 AN/EPS-117, 8.30, 13.63 to 13.64 AN/MPS-39, 9.2, 9.26 AN/SPS-40, 10.27, 11.32 to 11.33 AN/SPY-1, 13.62. AN/SPY-3, 13.69 AN/TPS-59, 8.30, 13.63 to 13.64 AN/TPS-63, 12.18 AN/TPS-77, 13.63 to 13.64 AN/TPS-78, 13.65 to 13.66 Analog-to-digital (A/D) converters, 6.35 to 6.40.     I_2 Anechoic chamber, 14. 
 Noblit, Ref. 22.) canceled in the postdetection subtracter at the IF output which retrieves the angle-error information. The log IF performs essentially as instantaneous AGC, giving the desired constant angle-error sensitivity of the difference signal normal- ized by the sum signal. 
 The fundamental reasons for this are related to the ratio of the wave - length of the radiation and the physical dimensions of the target. In most cases for  GPR, the ratio is close to unity. This compares very differently with an optical image,  which is obtained with wavelengths such that the ratio is considerably greater than  unity (typically 100,000:1). 
 The stated resolution of an A/D converter is the number of  output data bits per sample. The full-scale voltage range of a Nyquist rate converter  is given by VFS = 2NQ, where N is the stated resolution and Q is the least significant  bit (LSB) size. Signal-to-Noise-Ratio (SNR). 
 RANGE DOPPLER  DOMAINS )3!2 IMAGING IS IMPORTANT IN MILITARY APPLICATIONS SUCH AS TARGET RECOGNITION AND CLASSIFICATION SINCE IT CAN USUALLY RECOGNIZE THE CLASS OF TARGET  THAT CAN ALSO BE USED TO CUE WEAPON SYSTEMS 4HE NEED FOR COHERENT COUNTERING OF THESE IMAGING SENSORS IS A HIGH PRIORITY FOR %7 4HE REFERENCES   PRESENT THE . Ó{°xÓ  2!$!2 (!.$"//+  DESIGN OF A PIPELINED ALL 
 TIME h@WEATHERv THAT IS  IRREGULARITIES  WAVES  AND OTHER DYNAMIC PROCESSES  THOUGH MEASURES OF VARI 
 TER IN ADDITION TO THE TARGET 2#3 4HE AVAILABLE PARAMETER IS TARGET RADIAL VELOCITY "IRDS TYPICALLY FLY AT  KNOTS OR LESS  WHEREAS TARGETS OF CONCERN USUALLY HAVE AIRSPEEDS OF  KNOTS OR MORE )F THE RADAR CAN MAKE UNAMBIGUOUS RADAR DOPPLER MEASUREMENTS OF  EG  o KNOTS WITH A SINGLE #0) COHERENT PROCESSING INTERVAL   THE RADAR CAN  DETERMINE THE TRUE RADIAL VELOCITY OF EACH RADAR ECHO FROM RETURNS OF THREE OR MORE CONSECUTIVE #0)S AT DIFFERENT 02&S 4HE ACCEPTANCE CRITERIA OF THE 36# ALGORITHM  RELATES TO THE TYPE OF TARGET AIRCRAFT   MISSILE  BIRD  ETC  BEING ACCEPTED OR REJECTED )N GENERAL  THE CRITERIA ACCEPTS LARGE TAR 
 11.5) can  overcome this limitation of a short pulse since it can achieve a resolution equivalent to that of  a short pulse, but with the energy of a long pulse. Second, the required signal-to-clutter ratio  depends on the pulse width because of the change in clutter statistics (probability density . 484 INTRODUCTION TO RADAR SYSTEMS  function) with short pulse widths, as discussed in Sec. 
 The other major type of active jammer is deceptive ECM (DECM). Deception  is  the intentional and deliberate transmission or retransmission of amplitude, frequency,  phase, or otherwise modulated intermittent or CW signals for the purpose of mislead - ing in the interpretation or use of information by electronic systems.3,13 The categories  of deception are manipulative and imitative. Manipulative  implies the alteration of  friendly EM signals to accomplish deception, whereas imitative  consists of introducing  radiation into radar channels that imitates a hostile emission. 
 Ray, “A first look at the operational (data quality) improvements provided  by the Open Radar Data Acquisition (ORDA) system,” in 21st Int. Conf. on Infor. 
   TO 
 In order to make possible this co m- pression the transmitting signal must be modulated in the pulse (intra -pulse modulation), again  in order to obtain marks within the pulse duration.  Digital and analog procedures will be d e- scribed in the following.   8.8.1  Compression of a fr equency modulated pulse (chirp)   One of the first procedures for the realization of pulse compression involved the frequency modulation of the transmitting pulses. 
 Mitnik, L.; Dubina, V .; Lobanov, V . Cold Season Features of the Japan Sea Coastal Zone Revealed by Ers Sar. In Proceedings of the IEEE International Geoscience & Remote Sensing Symposium, Boston, MA, USA, 8–11 July 2008. 
 125. Nathanson, F., Technology Service Corporation: private communication, May 1988. 126. 
  D" -ARGIN FOR AT MOST  D"  SENSITIVITY LOSS 'ATED 0HASE .OISE $ENSITY &LOOR   D"C(Z 02& 
 We shall not be concerned about the problem of amplification,  although it is an important aspect of receiver design. Instead, we shall be more interested in the  effect of the detector on the desired signal and the noise.  One form of detector is the envelope detector, which recognizes the presence of the signal  on the basis of the amplitude of the carrier envelope. 
 FIELD !NTENNA -EASUREMENTS   .ORWOOD  -! !RTECH (OUSE     ( - !UMANN  ! * &ENN  AND & ' 7ILLWERTH  h0HASED ARRAY ANTENNA CALIBRATION AND PATTERN  PREDICTION USING MUTUAL COUPLING MEASUREMENTS v  )%%% 4RANS !NTENNAS AND 0ROP  VOL    NO  PP n  *ULY   % "ROOKNER  h0HASED ARRAYS AND RADARS n PAST  PRESENT  AND FUTURE v  -ICROWAVE *  VOL    PP n  *ANUARY   2 - 3CUDDER AND 7 ( 3HEPPARD  h!.309 
 Although ttlc  chi-square distribution with other than m = 1 has been observed empirically to give a reason-  able fit to the radar cross section distribution of many targets, there is no physical scatterirlg  mechanism on which it is based. It has been said that the chi-square distribution with ~n = 2  (Swerling cases 3 and 4) is indicative of scattering from one large dominant scatterer together  with a collection of small independent scatterers. However, it is the Rice distribution that  follows from such a The Rice probability density function is  where s is the ratio of the radar cross section of the single dominant scatterer to the total cross  section of the small scatterers, and Io( ) is the modified Bessel function of zero order.'"his is  a more correct description of the single dominant scatterer model than the chi-square with  m = 2. 
 Thepowertransmitted bytheradarwilldependonthetypeoffunction itistoperform aswell asthetargetmaximum rangeandpossibly thepastbehavior ofthetarget.Thustheradar resource oftimeisaffected morebythelong-range targets, andtheradarpowerismore affected bythetacticalfunction. Thedataprocessor, aswellastheradar,cancausethesystemtorunoutofavailable tllne. Thetimerequired toprocesseachtargetdwellaswellastheamount ofcomputer memory neededpertargetisusuallyindependent ofthetargetrange.Thusthesaturation limitofthe computer willbereached ifitisgiventoomanydatapointsperunittime.Thisismorelikelyto occurwithshort-range targetssincetheygenerally requireahigherdataratethanlong-range targets. 
 AES-13, pp. 11-16, January, 1977.  90. 
 Vu, V .T.; Sjögren, T.K.; Pettersson, M.I. Fast factorized backprojection algorithm for UWB SAR image reconstruction. In Proceedings of the 2011 IEEE International Geoscience and Remote Sensing Symposium, Vancouver, BC, Canada, 24–29 July 2011; pp. 
 ALARM RATE #&!2  BY RANKING ORDERING THE SAMPLES FROM SMALLEST TO LARGEST  THE TEST SAMPLE WITH THE REFERENCE CELLS 5NDER THE HYPOTHESIS THAT ALL THE SAMPLES TEST AND REFER 
 3.10. Aslong asthe relative positions ofthe objects inthetarget layer arerandom,l weadd the power received from each object inthe area tofind the average \’-. / ,, rII h L I\ --&l-FIG.3.15.—The area contributing totheinstantaneous power received from anextended surface target ishmited inrange andazinluth hytheresolution oftheradar system. 
 REFLECTOR EFFECT 3URFACE TILTING ALSO MOVES THE RADAR ANGLE OF  INCIDENCE WELL INTO THE FAR SIDELOBES OF MOST SURFACES ON THE VESSEL 4HUS VERTICAL BULKHEADS OFTEN ARE TILTED INBOARD  , 
 This isaperfectly feasible system and has worked inthe field. Itis not nearly socomplicated asappears from thedescription since the two transmitters can becombined, asalso can most parts ofthe receivers. The apparatus isessentially like that ofthesystem described inSec. 
 The five narrow hyperbolic bands (iso-doppler  contours) define the area that contributes to clutter in the selected doppler filter.  The shaded intersections represent the area, or clutter patches, that contributes to  the range-gate −doppler-filter cell. Each clutter patch contributes clutter power as a  function of the antenna gain in the direction of the clutter patch and the reflectivity  of the clutter patch. 
 Lett. 2010 ,7, 846–850. [ CrossRef ] 19. 
 Gini and F. Lombardini, “Multibaseline cross-track  SAR interferometry: A signal-processing perspective,” IEEE Aerospace and Electronic Systems  Magazine , vol. 20, no. 
 DIMENSIONAL MAPS OF THE ECHO SOURCES OF TEST OBJECTS  &IGURE  IS AN EXAMPLE OF SUCH AN IMAGE )N THIS CASE  THE PROCESSING REQUIRED  TO GENERATE THIS IMAGE IS A DOUBLE &OURIER TRANSFORMATION  ONE FROM THE FREQUENCY DOMAIN TO THE TIME DOMAIN AND THE OTHER FROM THE ANGLE DOMAIN TO THE CROSS 
     ,OCK 
 Radar System Engineering  Chapter 6 – Radar Receiver Noise and Target Detection  39     The amplitude of the I/Q detector outp ut is:          Figure 6.12  Receiver stages of a Radar of with I/Q detector.   € 0U=2I+2Q=2I2cosϕ+2Q2sinϕ ϕ=arctanI Q f=dϕ 2πdt. Radar System Engineering  Chapter 7 – CW and FM -CW Radar  41     7 CW- and FM-CW Radar   The CW ( continuous wave) Radar continuously radiates with the power PT. 
        LN;   =  LN; 00  0 0D &! &!SIGN  DDD0  = 
 C. Johnson and H. Jasik (eds.), Antenna Engineering Handbook , 2nd Ed., New York: McGraw-Hill  Book Company, 1984, pp. 
 Novak, S. D. Halversen, G. 
 Vander Schurr, R. E., and P. G. 
 The terminology n indicates  that the first n sidelobes are held to the specified level. ch13.indd   28 12/17/07   2:40:00 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Kitaigorodskii, “On the theory of the equilibrium range in the spectrum of wind-generated  gravity waves,” J. Phys. Oceanogr ., vol. 
 Equation (13.18), which applies for Rayleigh scattering, may be used as a /  basis for measuring with radar the sum of the sixth power of the raindrop diameters in a unit  volume. The Rayleigh approximation is generally applicable below C band (5 cm wavelength)  and, except for the heaviest rains, is a good approximation at X band (3 cm). Rayleigh  scattering usually does not apply above X band. 
 Although diﬀerential interferometric synthetic aperture radar (DInSAR) can cover a shortage of traditional ground measurement methods, its capacity in highway deformation monitoring is limited by its well-known spatial-temporal decorrelation and atmospheric delay e ﬀects [ 3,4]. Time-series technologies, such as permanent scatterer interformetry (PSI) [ 5], small baseline subset (SBAS) [ 6,7], temporally coherent point InSAR (TCP-InSAR) [ 8], and so on [ 9], have been proven to possess great capacities for large traﬃc infrastructure monitoring (i.e., railways, highways, and bridges) [ 10–21]. They can pick up ground displacement information with millimeter-level precision through high coherence points, maintaining long-term stable backscatter characteristics. 
 p11. 1462 1471. 1)cccrnhcr. 
 Good receiver design is based on maximizing the output signal-to-noise ratio. As  described in Sec. 10.2, to maximize the output signal-to-noise ratio, the receiver must be  designed as a matched filter, or its equivalent. 
 GET ECHOES WILL BE IMMERSED IN RETURNS FROM THE %ARTHS SURFACE  THAT IS  CLUTTER )N ORDER  TO DETECT THE TARGETS  THE PROPERTIES OF THIS CLUTTER NEED TO BE UNDERSTOOD SO THAT THE CHOICE OF FREQUENCY  WAVEFORM  AND SIGNAL PROCESSING ARE COMPATIBLE WITH THE NEED TO SEPARATE TARGET ECHOES FROM CLUTTER  AND ALSO SO THAT THE REQUIRED DYNAMIC RANGE OF THE RADAR CAN BE CORRECTLY SPECIFIED %ARLY (& RADAR EXPERIMENTS ESTABLISHED THAT THE STRONG GROUND CLUTTER OBSERVED  VIA SKYWAVE PROVIDED AN INDICATION OF THE PHYSICAL CHARACTERISTICS OF THE ILLUMINATED TERRESTRIAL SURFACE %XTENSIVE OBSERVATIONS MADE AT THE .AVAL 2ESEARCH ,ABORATORY VIEWING ALTERNATELY !TLANTIC /CEAN AREAS AND CENTRAL 5NITED 3TATES AREAS INDICATED THAT  AVERAGED OVER A WIDE AREA  SEA CLUTTER POWER LEVELS WERE USUALLY ABOUT AN ORDER OF MAGNITUDE HIGHER THAN THOSE FROM AN AREA OF SIMILAR SIZE IN THE CENTRAL 5NITED 3TATES ,ATER OBSERVERS NOTED EXTREMELY LOW BACKSCATTER FROM ICE 
  (ERCULES AIRCRAFT 4HE RADAR IS NONROTATING AND HAS A  FIELD OF VIEW 4HE RADAR USES ITS  M  FULL  FIELD 
 RELATIVE  DATA (OWEVER  IT IS DIFFICULT TO SEE HOW THEY WILL SURVIVE IN THEIR ORIGINAL FORM AS MARINE RADAR MOVES AWAY FROM UTILIZING MAGNETRON 
 It was noted that land returns were better de ﬁned than with S-band equipment but the ‘pin-point ’deﬁnition of target returns made them rather dif ﬁcult to distinguish from sea clutter. It was also noted that banking of the aircraft by more than 5 °or 6 ° caused total loss of signal and ‘bumpy weather ’could cause the signal returns to be intermittent. This was due to the lack of roll stabilisation of the scanner and would have been more noticeable on the X-band equipment than for S-band, due to the narrower azimuth and elevation beamwidths. 
 ING ANGLES AT THESE WIND SPEEDS &)'52%   0OLARIZATION RATIO VERSUS WIND DIRECTION FOR 8 
 ING THE ALGORITHMS OF A SUITABLE MODEL OF THE EXAMINED SYSTEM BY MEANS OF COMPUTER PROGRAMS 0ROPER INPUTS TO THE MODEL  CORRESPONDING TO THE MOST RELEVANT OPERATIONAL CONDITIONS FOR THE REAL SYSTEM  CAN BE GENERATED  BY THE SAME COMPUTER PROGRAMS 4HE  OUTPUTS OBTAINED ARE COMPARED WITH SOME REFERENCE VALUES EXPECTED OR THEORETICAL  TO ASSESS SYSTEM PERFORMANCE 7HEN RANDOM INPUTS ARE PROVIDED   A NUMBER OF STATISTI 
 The objective of frequency agility and diversity is to  force the jammer to spread its energy over the entire agile bandwidth of the radar; this  corresponds to a reduction of the jammer density and resulting ECM effectiveness.29 A good example of the use of the frequency domain for purpose of ECCM is the  Senrad, an experimental long-range air-surveillance radar built and tested at the Naval  Research Laboratory (U.S.)135 Senrad was an example of how to build a radar so as  to force the jammer to dilute its radiated energy per unit bandwidth; it includes both  frequency agility and frequency diversity. This radar shows that its unusually wide  bandwidth allows a reduction of the effectiveness of the noise jammer that can seri - ously degrade more narrowband radars. Frequency agility, diversity, and instantaneous wideband techniques represent a  form of ECCM in which the information-carrying signal is spread over as wide a  frequency (or space or time) region as possible to reduce detectability by ESM and/or  ARM and make jamming more difficult. 
 The sum and difference patterns are scanned simultaneously. The difference-pattern null in a phased array system gives good beam-pointing accuracy. Absolute beam-pointing accuracies to within less than one-fiftieth of a (scanned) beamwidth have been measured with scans up to 60°.20 The accuracy is limited by phase and amplitude errors. 
 TION GAIN  @ IS NEARLY IDENTICAL FOR THE  1TK  MODELS NO       AND  IN 4ABLE   (OWEVER  THE VELOCITY GAIN  A DIFFERS CONSIDERABLY &OR RANDOM CHANGES IN ACCEL 
 AREPS considers range- and azimuth angle–dependent influences from surface  features to include terrain elevation, finite conductivity, dielectric ground constants,  and scattering effectiveness factors. The terrain elevation data may be obtained from  the National Geospatial-Intelligence Agency’s (NGA) Digital Terrain Elevation  Data (DTED) or from any other suitable source. The finite conductivity and dielec - tric ground constants may be selected from those defined by the International  Telecommunication Union, International Radio Consultative Committee (CCIR),25  or from any other suitable source. 
 Military interest in 3D radar stems from its ability to determine the height of a noncooperating target, along with its range and azimuth. Because of its better angu- . (h) FIG. 
 All the phase commands can then be delivered simultaneously. 7.4 APERTUREMATCHINCANDMUTUAL COUPLING48 Significance of Aperture Matching. An antenna is a device that acts as a transformer to provide a good match between a source of power and freeROW PHASE COMMANDSPHASESHIFTER AMPLIFIERS RADIATING ELEMENT SERIES FEED . 
 withincreasing height.therayswouldcurve upward andtheradarrangewouldbereduced ascompared tonormalconditions. Thisis calledsuhre(raction. Itsoccurrence israre.Thetermanomalous. 
 The Metox warning receivers were only just starting to be installed in U-boats and their impacton the performance of metric ASV was not yet fully appreciated. This would lead to an urgent requirement to develop cent imetric ASV systems, as described in this chapter. OPERATIONAL REQUIREMENTS FOR A.S.V. 
 PUTS AT 2& WITH PASSIVE CIRCUITRY TO YIELD SUM AND DIFFERENCE SIGNALS  AS SHOWN IN &IGURE  4HESE SIGNALS MAY THEN BE PROCESSED LIKE A CONVENTIONAL AMPLITUDE 
 SCAN RADAR 4HE ADVANTAGE OF TWO CHANNELS WITH OPPOSITE 
 Track chirp pulse  4. Track simple pulse  5. Coherent extended  range track  6. 
 Although boththeelevated andthesurface(evaporation) ductcanresultinextended radarranges.theconsequences oftheirpresence areoftenbad ratherthangood.Thepresence ofextended rangescannotalwaysbepredicted inadvance. Furthcrmore. theycannotbedepended upon.Theextension ofrangealongsomepropagation pathsmeansadecrease ofrangealongothers.orradioholes.Theseholesinthecoverage can seriously affectairborne surveillance radarsaswellasground-based andship-borne radars. 
 lt is capable of very rapid switching, of the order of a  nanosecond, but can handle only low power. Since the capacitance of a varactor varies with  the applied negative bias voltage, it may be employed as an analog (continuously variable)  phase shirter using either the loaded line or the hybrid coupled configurations. Power levels  are limited to a few milliwatts by the generation or harmonics and other nonlinear effects. 
 Values from 100 to 300 might be considered as more ~ypical.  There are many types of modulations used for pulse compression, but two that have seen wide  application are the linear frequency modulation and the phase-coded ptrlse.  C-> pulse compression. 
 The three-axis mount of (h) is simpler, bill also 11as similar  disadvantages because of weight and size.  In the above, the stabilization of the mount was assumed to be by some form of mechanical  compensation. Radars which electronically scan a beam in elevation (usually a pencil beam)  by either phase shifters or frequency scan can stabilize the beam in elevation as a correction to  the elevation scan orders, thus permitting a reduction in the size of the mount. 
 Allother voltages for the local oscillators, receiver, and AFC come inover wires inthe large cable connector from anexternal centralized supply. The various subunits inthe r-fhead aredesigned with plug connec-. SEC.11.12] ILL USTRA TIVE EXAMPLES OF R-F HEADS 429 tions sothat they may bequickly removed forservicing orreplacement with spare units. 
 Sachidananda. and D. S. 
 TO 
 [IGARSS 2000] , IEEE, Honolulu, 2000,   pp. 1570–1573. 71. 
 FLIGHT TRANSFER ALIGNMENT OF THE VARIOUS INERTIAL PLATFORMS AIRCRAFT  WEAPONS  AND RADAR  ! SET OF OUTPUTS IS PROVIDED TO THE MISSION MANAGEMENT COMPUTER FUNCTION  INCLUDING .ORTH 
 VECTOR WIND DATA RELATIVE TO SCATTEROMETRIC MEASUREMENTS REMAINS AN OPEN ISSUE 3CATTEROMETRIC DATA ARE BEING EXPLOITED FOR MANY PURPOSES OTHER THAN OCEANIC VEC 
 ALARM RATE APPROACHES  0 F    
 An electronically programmable gain adjustment may be help - ful to correct module-to-module variations, allowing less demanding specifications.  The trimmer would also provide a degree of freedom in aperture control for special  situations. Because the noise figure has been established, the feed network may be  split to give separate optimum aperture amplitude distributions for transmitting as  well as for receiving on sum and difference channels. 
 TO 
 The resulting power spectrum due to the antenna scanning is //(/) # F2(£9 °S/ST (16'14) where 0 = antenna rotation rate a = horizontal antenna aperture This spectrum can be approximated by a gaussian distribution with standard deviation ac = 0.265- = 0.265— * 0.265— (16.15)n 6fl X where X and a are in the same units, 6a is the one-way half-power beamwidth, and n is the number of hits per beamwidth. The approximation 0a « \la is rep- resentative of antenna distribution yielding acceptable sidelobe levels. It can be seen that the differential return is , </G2(0) </G2(0) .AG2(0)# ——A0 = ——-QTp (16.16) UU UU This suggests7'13 that a correction signal in the reverse sense to AG2(0) be ap- plied, as shown in Fig. 
 7, p. 622.TABLE   9.1  Inventory of Range-Error Components* ch09.indd   43 12/15/07   6:07:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The wide-area surveillance application makes automatic detec- tion and tracking very desirable; the single transmitter footprint shown in Fig.24.1 has 800 receive range-azimuth cells. Tracker requirements differ from those of other sensors in that it is generally necessary to have thresholds that permit many natural responses. It is common practice to defer target declaration until a track is recognized and thereby to reduce the false-alarm rate. 
 If meter-kilogram-seconds  (mks) units are used, the calculation of Z will have dimensions of m6/m3. Conversion  to the more convenient units of mm6/m3 requires that Z be multiplied by the factor 1018.  Furthermore, expressing Pr and r in common units of dBm (dB relative to 1 milliwatt)  and km requires that Z also be multiplied by 103. 
 The greater azimuth resolution provided byasharper beam isalso useful inresolving com- plicated target. situations. The only drawback ofmicrowave radar for ship search istheresultant narrowing ofthebeam inelevation; inorder to keep therolling ofthe ship from tilting thebeam away from the surface ofthe sea, either the antenna mount must bemechanically stabilized (Chap. 
 2 1. Ahel, J. E., S. 
 MTI RADAR  2.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 The maximum signal-to-noise ratio available from an N-pulse filter is N times  the signal-to-noise ratio of a single pulse, assuming all pulses have equal ampli - tude. When weighting is applied to reject clutter and control the filter sidelobes, the  peak output signal-to-noise ratio is reduced. The filter mismatch loss is the amount  by which the peak-output signal-to-noise ratio is reduced by the use of weighting. 
 5.  9. Hewlett-Packard Application Notes, High Frequency Transistor Primer, Part 3, Thermal  Properties, p. 
 April. 1953.  I 6. 
 E. Belyea, and P. G. 
 The reflected  signal is also called scattering. Backscatter  is the term given to reflections in the opposite direction  to the incident rays.   Radar signals can be displayed on the traditional plan position indicator (PPI) or other more  advanced radar display systems. 
 2.74  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 introduced by the A/D converter is 2 2 1 1 2 /[( ) ].N−  The limit on the MTI improve - ment factor that this imposes on a signal reaching the full excursion of the phase detec - tor is found by substituting in the following equation from Table 2.5:  IA A N= = −    =−20 201 2 1 3 0201log l og [( ) . ]log [∆( ( ) . ] 2 1 3 0N−  (2.58) Because two quadrature channels contribute independent A/D noise, the average  limit on the improvement factor of a full-range signal is  IN N= −  = − 20 2 13 0 220 2 1 1 5 log ( ).log [( ) . 
 In other designs the scan is i ../ saw-tooth with the beam sweeping across the plane of scan and then stepping back almost  instantaneously to its starting point. The saw-tooth scan is generally preferred in radar applica-  tions. Such antennas would be used where a small angular sector needs to be covered with a  rapid scan rate. 
 TDWR operates at C band (5.60-5.65 GHz). The antenna rotates at 4.33 rpm and  has a 0.55° one-way beamwidth. The PRF is 1066 Hz. 
 50 -59, Fi.:bruary,  1965.  25. Josefsson, L. 
 408-413.  24. Weiss, H. 
 Standard conditions are precisely deﬁned as follows: Figure 1.7 - Refraction.d 1.22 h= hh . 10Pressure = 1013 mb decreasing at 36 mb/1000 ft of height Temperature = 15˚C decreasing at 2˚C/1000 ft of heightRelative Humidity = 60% and constant with height. These conditions give a refractive index of 1.00325 which decreases at 0.00013 units/1000 ft of height. 
 To use  the equality of Eq. (14.13) in Eq. (14.15), write Ae = Pa A, where Pa= antenna aperture  efficiency, and A= physical aperture area assumed to be rectangular of width D and height H. 
 The  ambiguity diagram is represented in Fig. 11.l lb. With a single pulse the time-delay- and  frequency-measurement accuracies depend on one another and are linked by the pulse width 1. 
 8. Lawson, J. L., and G. 
 Tllc ~>rograrntiied control of the receiver gain to maintain a constant  ccllo sigrl;il strerigtll is callctl scvrsirirliry tirjrc i.o,ttrol (STC'). It is all effective i~letllod for  eli~nirlatirlg radar eclloes due to urlwar~ted birds and insects.  SI'C makes use of the inverse fourth power variation of signal strength with range. 
 If the waveform bandwidth is 1 GHz and the analyzer can process only a 10-MHz bandwidth, the range coverage is restricted to under 1 percent of the transmitted waveform length. To increase the range coverage, a wider processing bandwidth is required. This stretch ap- proach allows the full range resolution of a wide-bandwidth waveform to be re- alized with a restricted bandwidth processor. 
 QUENCY 
 Ufimtsev, “Approximate computation of the diffraction of plane electromagnetic waves at  certain metal boundaries, Part I: Diffraction patterns at a wedge and a ribbon,” Zh. Tekhn. Fiz. 
 T. K. Johnson, “Block adaptive quantization of Magellan SAR data,” IEEE  Transactions on Geoscience and Remote Sensing , vol. 
 This so-called pulse-pair algorithm , therefore, is an effi - cient spectral moment estimation technique. However, it should be applied only when  one is certain to have a pure weather signal in white noise; otherwise, other spectral  components or non-white noise will bias the spectral moment estimates. For many past operational radars, the pulse-pair processor was the technique of  choice. 
 35. Glegg, K. C. 
 12, pp. 75--80, December, 1969.  46. 
 Berkowitz, R.: "Modern Radar," John Wiley & Sons, New York, 1965. 11. Reintjes, J. 
     
 2.10). Such help isofnoavail against rain unless the target echo isreceived over atime long compared tothe rain fluctuation period discussed above. Todistinguish atarget inthe midst ofrain clutter, wemust make use ofsome peculiar feature ofaraindrop asaradar target. 
 The RF filter provides rejection of out-of-band  interference, including rejection at the RF image frequency. After downconversion to  IF, a bandpass filter provides rejection of unwanted signals and sets the receiver ana - log-processing bandwidth. Additional gain is provided at IF to overcome losses and  raise the signal level required for subsequent processing and to set the correct signal  level into the A/D converters. 
  &)'52%   A  "ANDLIMITED  REAL PASSBAND SIGNAL SPECTRUM BEFORE SAMPLING AND B  SIGNAL SPECTRUM  AFTER SAMPLING   
 Nevertheless, the functioning of the antenna is complex, and there is need for providing test or monitoring circuitry. The decision to point a beam in a certain direction is made somewhere in the radar control system and is normally defined by two direction cosines. A test or monitoring circuit should establish the correct functioning of all components, including all beam-pointing computations, electronic drivers and phase shifters or switches, and all their interconnections. 
 The 6AK5 and 717 are very similar inelectrical performance and give alower noise figure than the 6AC7; however, the latter isstill widely used. TABLE 12.1.—AvERAGE NOISE FIGURE Circuit Grounded-cathode pentode to grounded-cathode pentode Grounded-cathode triode to grounded-grid triodeTube type 1st 2nd stage stage 6AC7 6AC7 6AK5 6AK5 6AK5 6AK5 6AK5 6AK5 6AK5 6AK5 6AK5 6J6 6J4 6J4Intermedi- ate frequency, Mc,/sec 30 30 60 30 30 60 180Over-all receiver bandwidth, Me/see 1.5 6 16 1.5 8 12 3Average noise, db. 3,9 3.3 6.5 15 2,2 3.5 5.5 The o~eratin~ voltage and current forthe first tube are frequently influenced bydesign considerations other than noise figure. 
 6ILLE $ISTRIBUTION = OF THAT CELL ONLY   4HE PHASE  HISTORY IS THEN USED FOR COMPENSATING THE RANGE MIGRATION AND THE PHASE SHIFT ON THE HIGH ;FINE= RESOLUTION RANGE DATA 4HE FINAL IMAGE IS SHOWN IN &IGURE ; B=   4HE SHARPENING OF THE TARGET IMAGE IS QUITE EVIDENTv "ARBAROSSA AND &ARINA ASSUMED A POINT TARGET IN THEIR SIMULATION 4HEY OBTAIN A PRECISE LOCATION OF A SIMULATED MOV 
 Each dc power supply must have a capacitor bank large enough to supply the energy drawn by its solid-state modules during an entire pulse, and each power supply must recharge its capacitor bank smoothly between pulses without drawing an excessive current surge from the power line. While the required power supply is generally not a "catalog" power supply, there are plenty of solid-state devices and circuits available to satisfy these requirements. As a result of unavoidable losses in combining the outputs of many solid-state devices, it is especially tempting to avoid combining before radiating, since com- bining in space is essentially lossless. 
 As mentioned earlier, hard X-rays and ultraviolet radiation raise D-layer ion - ization dramatically with consequent increases in radiowave absorption. Within an  hour and for a day or so after, flare-generated particle bursts start to arrive and are  channeled down the magnetic field lines at high latitudes, causing ionospheric heat - ing and associated diffusion to lower latitudes, together with a variety of magnetic  field perturbations. HF propagation is often severely disrupted. 
 13. Xue, F.; Lin, Y.; Hong, W.; Chen, S.; Shen, W. An Improved H/ αUnsupervised Classiﬁcation Method for Circular PolSAR Images. 
 STATE !.303 
 In addition to providing these functions, the processor must be low-powered, have low mass, operate for many years without manual repair, and have radiation-hardened memories. Technology using 16K random-access-memory (RAM) chips and very-large-scale-integration (VLSI) computers can reduce "typical" system power and mass from 3 kW and 2000 Ib, respectively, to 400 W and 400 Ib. The Defense Advanced Research Projects Agency (DARPA) and others have been working on the development of an advanced on-board signal processor (AOSP) and have made considerable progress.10 The concern here is to develop a very reliable and survivable on-board computer using gallium arsenide circuitry that can resist the electromagnetic pulse and other radiation effects pro- duced by nuclear detonations. 
 July. 1975.  128. 
 A single radar transmitter and receiver is switched among the four sets of feeds  on a time-shared basis every 90° rotation of the mirror. As in the antenna of Fig. 7.13, the  parabolas consist of closely spaced parallel wires that reflect the polarization radiated by the  feed, but pass the orthogonal polarization. 
 C. Rose, “AN/SPY-1 planned improve - ments,” in Conf. Rec. 
 TO 
 02& PULSE DOPPLER RADAR !7!#3  WITH LARGE REJECTION OF UNWANTED CLUTTER L (& OVER 
 WAVE SPECTRUM CAN SOMEHOW BE SEPARATED INTO TWO PARTS  ONE CONTAINING LOW 
 UNITS  UNDER DUCTING  ATMOSPHERIC CONDITIONS 4HEREFORE  A  - 
 , 
 Thus, the required number of amplitude bits in the A/D converter as determined by the main-beam clutter is f(CWV)max (dB) + flue margin (dB) + 20 log (noise)(<7)j L 6 J where CEIL is the next larger integer. For the example cited in Fig. 17.18 where the maximum ClN is 53 dB at a 1000-ft altitude, and with a fluctuation margin of 10 dB and thermal noise at 1.414 quanta, the A/D requires at least 11 amplitude bits (plus a sign bit). 
 There are, however, limitations to the use of a low-noise front-end in some radar  applications. 7 A~ mentioned above, the cost, burnout, and dynamic range of low-noise devices  might not be acceptable in some applications. Even if the low-noise device itself is of large  dynamic range, there can be a reduction of the dynamic range of the receiver as compared to a  receiver with a mixer as its front-end. 
 44. L. K. 
 There have been at least three ways to apply solid-state transmitters to high-perfor - mance radars: (1) as a replacement for a vacuum tube transmitter in an already exist - ing radar; (2) as the transmitter for a new radar design; and (3) as an active aperture  phased array radar. An example of replacing an existing vacuum tube transmitter with a solid-state  transmitter is the U.S. Navy’s AN/SPS-40, a relatively modest capability UHF radar  for air surveillance.53 This radar was chosen for having its vacuum tube transmitter  replaced with a solid-state transmitter using transistor amplifiers because it already  used a long pulse waveform with a high duty cycle and pulse compression, which is  what solid-state radars usually require. 
 3.38  Applications  .......................................................  3.38  Formats  .............................................................  3.39  Synchronization  ................................................. 
 It was used in the ASR-9 airport surveillance  radar and in the WSR-88D Nexrad doppler weather radar (where its operating band is  from 2.7 to 3.0 GHz), as well as in other radars. Very high-power klystrons are employed in linear accelerators such as found at the  Stanford Linear Accelerator Center.7 Klystrons for this application, for example, might  have 75 MW peak power with 50% efficiency using solenoid magnets; or 60–75 MW  peak power with 60% efficiency using periodic permanent magnets. Improvements to the klystron as a radar power source are discussed later in the  subsection on hybrids, of which the clustered-cavity klystron is a good example of  what can be provided in the way of high power and wide bandwidth. 
 The chief reason for this  failure was attributed to the receiver's being designed for CW communications rather than for  pulse reception. The shortcomings were corrected, and the first radar echoes obtained al  NRL using pulses occurred on April 28, 1936, with a radar operating at a frequency of  28.3 MHz and a pulse width of 5 µs. The range was only 2! miles. 
 MATES COULD BE USED FOR IMPROVED FALSE 
 CAPACITY SEMICONDUCTOR MEMORIES IS THE TECHNOLOGICAL BREAKTHROUGH THAT HAS MADE THE DESIGN OF A WORKING AREA -4) A REALITY 4HE  AREA -4) IS BETTER KNOWN  TODAY AS A CLUTTER MAP  BUT BOTH TERMS ARE USED 4HE CLUTTER MAP MAY BE CONSIDERED AS A TYPE OF #&!2 WHERE THE REFERENCE SAMPLES   WHICH ARE NEEDED TO ESTIMATE THE LEVEL OF THE CLUTTER OR CLUTTER RESIDUE   ARE COLLECTED IN THE CELL UNDER TEST ON A NUMBER OF PREVIOUS SCANS 3INCE AIRCRAFT TARGETS USUALLY MOVE SEVERAL RESOLUTION CELLS FROM ONE SCAN TO THE NEXT  IT IS UNLIKELY THAT THE REFERENCE SAMPLES WILL BE CONTAMINATED BY A TARGET RETURN !LTERNATIVELY   BY MAKING THE AVERAG 
 13s8. The Generation ofSharp Pulses.-Sharp pulses needed for triggers, range markers, and other indicator uses can begenerated ina number ofways, Figure 13.18 indicates three methods bywhich asteep (a) (b) (c) FIG. 13.18,—Simple pulse-generating circuits. 
 ONLY CORRELATION  THE  0 &! IN EACH RANGE 
 N. McDonough, Synthetic Aperture Radar: Systems and Signal Processing ,  New York: John Wiley & Sons, Inc., 1991. 31. 
 8.8 RANDOM ERRORS IN ARRAYS  In the analysis of the effects of reflector-antenna errors in Sec. 7.8 only the phase error was  considered. In an array, however, other factors may enter to cause distortion of the radiation '. 
 Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 4.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 4.3 DYNAMIC-RANGE AND STABILITY  REQUIREMENTS Doppler processing separates moving targets from clutter and allows them to be  detected while only competing against thermal noise, assuming that the targets have  sufficient radial velocity ( > 2VR/l) and the PRF is high enough for an unambiguous  clutter spectrum. Coherence, the consistency of phase of a signal’s carrier frequency  from one pulse to the next, is crucial for doppler processing. 
 In an ISAR (inverse synthetic aperature radar) the relative motion is provided by the movement of the target. Shape. The size of a target is seldom of interest in itself, but its shape and its size are important for recognizing one type of target from another. 
 Figure 8.5  Coherent pulse Radar.   Two various fundamental methods of Doppler analysis are known and will be subsequently  and shortly introduced. [7]. 
 By taking  I: ± jkL\, the effective phase center can be shifted depending on the value of k. (The factor j  multiplying the difference pattern signifies a 90° phase shift added to the difference signal  relative to the sum signal.) The use of this technique in an AMTI radar to compensate for the  effects of platform motion is called DPCA1 which stands for Displaced Phase Center Antenna.  The sum and difference patterns can be obtained by connecting a hybrid junction to the  outputs of the two antenna feeds as described in Sec. 
 Beamforming now requires com - bining the subarrays for suitable sum and difference patterns. Figure 13.33 a shows  a method of combining opposite subarrays into their sums and differences. All  sum channels are then added with proper weighting to obtain the desired ampli - tude distribution. 
 Cosinusoidal amplitude variation over the passband creates symmet- rical paired echoes in the time domain in addition to the main signal g(t\ whose shape is uniquely determined by G(/). The echoes are replicas of the main signal, delayed and advanced from it by nlB s and scaled in amplitude by aJ2. Pair 2. 
 At microwaves, the  small-signal equivalent circuit of the PIN diode may be represented as a series RC circuit with  the capacitance determined by the area, thickness, and dielectric constant of the intrinsic  region. The capacitance is independent of the reverse-bias voltage. The series resistance is  determined by the resistivity and geometry of the meta1Jic-like P and N regions. 
 S .. and R.H. Turrin: Depolarization Properties of Offset Reflector Antennas,/£££ Trans .. 
 Ilowney, 1:. J., R. 14. 
 Target track history. The above methods of target classification depend on extracting some­ thing about the target other than its location. However, the target track, which is obtained  from location data alone, can provide significant information that can be used in the  identification process, especially in a military situation. 
 R. W. Larson, R. 
 B. Wetzel, “On microwave scattering by breaking waves,” in Wave Dynamics and Radio  Probing of the Ocean Surface , Chap. 18, O. 
 POLAR MEASUREMENTS OF  : AT HORIZONTAL :H  AND VERTICAL :V  POLARIZATIONS CAN PRO 
 Stein and S. S. Blackman, “Generalized correlation of multi-target track data,” IEEE Trans .,  vol. 
 T. Ulaby, “Vegetation modeled as a water cloud,” Radio Sci. , vol. 
 Soc. , vol. 77, pp. 
 H. Wakabayashi et al., “Airborne L-band SAR system: Characteristics and initial calibration  results,” Proc IGARSS’99 , vol. 1, pp. 
 Hence, exact measurements of vector winds at a point  are generally not possible. However, rotating winds or vortices can be detected and  ch19.indd   28 12/20/07   5:39:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 SENSING CIRCUIT.   42!#+).' 2!$!2   °ÓÎ !NOTHER TECHNIQUE IS TO USE A PAIR OF OSCILLATORSONE CONTROLLING THE TRANSMITTER  TRIGGER AND THE OTHER CONTROLLING THE RANGE GATE 4HE RANGE RATE IS CONTROLLED BY THE  BEAT FREQUENCY BETWEEN THE OSCILLATORS  WHERE ONE IS FREQUENCY 
 SOR DYNAMIC RANGE  DETERMINED BY THE NUMBER OF BITS IN THE DATAPATH  !LTHOUGH ))2 FIL 
 This process is incremented in 1-MHz steps over the ra- dar's operating band. A vertical sounding of the ionosphere 700 km downrange has been used as the electron distribution for all one-hop paths, and a sounding 1400 km downrange is used for two-hop paths. Figures 24.9 and 24.10 gave a night and day example of the ionosphere 700 km downrange from a radar located at 38.650N and 76.5O0W looking east. 
 Four  important facts should be noted: ● A tracking system should be associated with the automatic detection system (the  only exception is when one displays multiple scans of detections). ● The Pfa of the detector should be matched to the tracking system to produce the  overall lowest S/N required to form a track without initiating too many false tracks  (see Figure 7.38, later in this chapter). ● Random false alarms and unwanted targets (e.g., stationary targets) are not a prob - lem if they are removed by the tracking system. 
 " OR #LASS 
 71. Hsiao, J. K.: MTI Optimizatiorl in a Multiple-Clutter Environment, NRL Report 7860, Nar!ul  Research Laboratory, Washington, D.C., Mar. 
 The level of technical detail required to remedy this was outside the remit of IMO,  and it was agreed that a Technical Committee (TC80) within the International  Electrotechnical Commission10 (IEC) would determine technically based interpreta - tions of IMO radar performance standards. In addition, it was agreed that the IEC  standards would include test procedures, which could be used by national maritime  administrations (such as the Coast Guard in the United States of America) to test for  conformance of specific designs by manufacturers to IMO and ITU requirements.  Today, virtually all national administrations use IEC standards to assess radar and  most other IMO-defined navigational and radiocommunications equipment. 
 R. K. Raney, “Radar fundamentals: technical perspective,” in Principles and Applications  of Imaging Radar , F. 
 SCAN  OR # 
 In Proceedings of the 2018 ISPRS TC III Mid-term Symposium Developments, Technologies and Applications in Remote Sensing, Beijing, China, 7–10 May 2018. ©2019 by the authors. Licensee MDPI, Basel, Switzerland. 
 BEAM AND CROSS 
 258-263, May. 1972.  53. 
 It can be shown  that if the phase of the illumination function is reversed f′ = −f, the desired virtual  distribution function is displaced ahead of the aperture, as shown in Figure 3.21 b. In practice, performance is limited by the ability to produce the required illumina - tion function. As the displacement increases, a larger physical aperture size is required  to produce the desired virtual aperture size owing to beam spreading. 
  AND +U 
 TIONS UTILIZING THE 0 
 Howard, D. D.: Investigation and Application of Radar Techniques for Low-Altitude Target Track­ ing. I EE International Radar Conference, RADAR-77, London, Eng., Oct. 
 QUALIFIED HARDWARE  NOR SYSTEM INTEGRATION AND TEST  FOR WHICH THE INTERESTED READER IS DIRECTED TO STANDARD REFERENCES   "ASIC /RBIT #HARACTERISTICS   5NLIKE AN AIRBORNE PLATFORM THAT CAN GO ANYWHERE  AT ANY TIME SUBJECT TO FUEL AND AIR 
 where V^ = radar ground speed ^o = main-beam angle relative to velocity vector 6B = 3 dB one-way antenna beamwidth, rad A. = RF wavelength Clutter-Transient Suppression. When the PRF is changed for multiple-PRF ranging, or the slope is changed in linear FM ranging, or the RF carrier is changed, the transient change in the clutter return may cause degradation unless it is properly handled.34 Since the clutter is usually ambiguous in range in a pulse doppler radar, the clutter power increases at each interpulse period (IPP) as clut- ter return is received from longer-range ambiguities, until the horizon is reached. 
 Probability of Detection   The received and demodulated echo signal is processed by threshold logic. This threshold shall be  balanced so that as of  certain amplitude wanted signals being able to pass and noise will be  removed. Since high noise exists in the mixed signal tops which lie in the range of small wanted  signals the optimized threshold level shall be a compromise. 
 60. Siegel, K. M.: Bistatic Radars and Forward Scattering, Natl. 
 Ifthe leading edge of a pulse strikes a target at a slightly greater range whilethe trailing part of the pulse is still striking a closer target, it is obvious thatthe reﬂected echoes of the two targets will appear as a single elongatedimage on the radarscope. Power Relation Theusefulpowerofthetransmitteristhatcontainedintheradiatedpulses and is called the PEAK POWER of the system. Power is normally measuredas an average value over a relatively long period of time. 
 The spot size ofacathode-ray tube depends upon the tube type, the performance ofthe individual tube, the voltage employed, the design offocus and deflecting coils, and the intensity level atwhich the tube isoperated. Inthe series ofmagnetic tubes used forradar, spot size isroughly proportional tothe tube radius and isusually such that between 150and 200 spots can beresolved along thedisplay radius. Inthis discussion, the number ofresolvable spots inaradius will. 
 '  The log-FTC receiver described in Sec.' 13.8 has CF AR properties when the background  has a Rayleigh probability density function. The FTC, or fast time-constant, acts as a differen­ tiating circuit, . or high-pass filter, to remove the mean value of the clutter or noise. 
 Stocks of spare crystals were also found to be below speci ﬁcation, probably because of exposure to high RF ﬁelds. It was found that when three crystals were placed on the ground in the radar antenna beam at a distance of 60 ft from the scanner, two of them lost 3 dB in sensitivity. The other causes of poor sensitivity were due to the use of variable and frequency selectivepermanent echoes for setting up and aligning the radars. 
 on  Radar-/'resent mu/ Fwure, Oct. 23 · 25, 1973, pp. 201-206, IEE Conference Publication no. 
 14.11 14.6 Receivers  ................................................................  14.15  RF Amplification  ................................................  14.15 Generation of the Local-Os cillator Signal   ........... 
 Then, the coarse support set is estimated from the BP image. For every subaperture of WASAR, the least squares estimate on the support set is calculated. Then, the observation residual is calculated. 
 RECEIVE PAIR PERFORMING INDEPENDENT DETECTIONS WITHIN A SURVEILLANCE REGION COMMON TO ALL SUCH PAIRS 4ARGET LOCATION TYPICALLY MEASURES THE BASELINE AND TAKES SIMULTANEOUS RANGE 
 DIGITAL CONVERTERS CAPABLE OF DIRECT SAM 
 In addition to the amplitude and phase noise of the receiver-exciter and the trans - mitter, mechanically scanning antennas produce a modulation that is predominantly  AM. The combined effect is the sum of the residue powers produced by each compo - nent individually. Low Noise Frequency Sources. 
 SanDiego. Calif..May3.1960. 16.Cohen,W.,andC.M.Steinmetz: Amplitude andPhase-sensing Monopulse SystemParameters, ptsI andII.Microwave J..vol.2.pp.27-33,October, 1959,andpp.33-38,November, 1959;alsodiscussion hyF.J.Gardiner. 
 ARRIVAL $/!   ANGLE 
 45. Ziemer, R. E., T. 
 25-34, 1st qtr., 1963.  12. Ridenour, L. 
 Rec.,   part. 1 , March 1961, pp. 49–56. 
 A peak . RADAR TRANSMITTERS 205  Figure 6.lO Photograph of the V A-87E 6-cavity S-band klystron mounted on a dolly. (Courtesy Varian  Associates, Inc., Palo Alro, CA.)  beam voltage of 65 kV is required and its peak beam current is 34 amperes. 
 123-129,  December, 1960.  7. Barton, D. 
 130 VSWR, and isolation in CW radar, 72  Wave-interference radar, 554  Weather clutter, 498-507  Weather effects, on radomes, 269-270  Weather fix, 507  Weibull probability density function:  land clutter, 496  sea clutter, 480  Weighting, for time sidelobes, 426  Weinstock cross section models, 50  Whitening filter, 375  Wing-beat frequency, bird, 509  Within-pulse scanning, 314-316  by frequency scanning, 302-303  21--22 in 3D radar, 545  Wrap-up factor. 299  X-ray hazard, 466  Z, radar reflectivity factor, 500-501  Zero-crossings detector, 384-385  Zoning of lenses, 249, 251  True-hearing display. 271 Truetimedelays.inarrays. 
 The time variation is visualized by considering the target as a relatively rigid body  with normal yaw, pitch, and roll motions. The small changes in relative range of the  reflectors caused by this motion result in corresponding “random” change in the rela - tive phases. Consequently, the vector sum fluctuates randomly. 
 Huecks, arid A. G. Heaton: Improved Radio Altimeter, flireless dorld, vol. 
 Óx°ÎÈ  2!$!2 (!.$"//+  THESE SYSTEMS IN A RADAR APPLICATION IS RESET TIME )N A MILITARY APPLICATION  WHEN A  SYSTEM NEEDS TO BE RESET IN ORDER TO FIX A PROBLEM  THE SYSTEM NEEDS TO COME BACK TO FULL OPERATION IN A VERY SHORT PERIOD OF TIME 4HESE MULTIPROCESSOR SYSTEMS TYPICALLY TAKE A LONG TIME TO REBOOT FROM A CENTRAL PROGRAM STORE AND  HENCE  HAVE DIFFICULTY MEETING RESET REQUIREMENTS $EVELOPING TECHNIQUES TO ADDRESS THESE DEFICIENCIES IS AN ACTIVE AREA OF RESEARCH &INALLY  THESE PROCESSORS ARE GENERALLY USED FOR NON 
 The predominance of digital signal processing in modern radar systems has led  to almost universal need for Nyquist rate sampled data. In many modern radar systems,  digital I and Q data is now generated using IF sampling followed by digital signal pro - cessing used to perform the baseband conversion as described in Sections 6.10 and 6.11.  I/Q demodulators are still used, though their use is increasingly limited to wider band - width systems where A/D converters are not yet available with the required combination  of bandwidth and dynamic range to perform IF sampling. 
 4.2DELAY-LINE CANCELERS ThesimpleMTIdelay-line cancelershowninFig.4.4isanexample ofatime-domain filter. Thecapability ofthisdevicedependsonthequalityofthemediumusedasthedelayline.The delaylinemustintroduce atimedelayequaltothepulserepetition interval. Fortypical ground-based air-surveillance radarsthismightbeseveralmilliseconds. 
 Horton. B. M.: Noise-Modulated Distance Measuring System, Proc. 
 The attenuation resulting from these effects can becalculated for drops ofany given diameter. Reliable and accurate though they may be,such results are not inthemselves ofmuch use, for itisneither customary norconvenient todescribe arain interms ofthedrop diameter and the number ofdrops per cubic meter. Inany case, the drops are never allofone size and itisnot sufficient toknow merely the average diameter. 
 A conventional short  pulse at a different frequency might have to be generated at the end of the'long pulse to provide  coverage of the close-in range that is blanked by the long pulse. Since it only has to cover the  range blanked by the long pulse, it need not be of large power. A separate receiver, or matched  filter, might be needed for this short-range pulse. 
 CAL STRUCTURE  WHERE EACH LEVEL IS SUBORDINATE TO THE LEVEL ABO VE AND SUBPROGRAMS  ARE CALLED IN STRICT SEQUENCE  IS NECESSARY )T ALSO REQUIRES  AMONG OTHER THINGS  THAT SUBPROGRAMS NEVER CALL THEMSELVES RECURSIVE CODE  OR ANY OTHERS AT THEIR EXECUTION LEVEL 3UBPROGRAMS OBJECTS  ARE CALLED  RECEIVE EXECUTION PARAMETERS FROM THE LEVEL ABOVE THE PARENT   AND RETURN RESULTS BACK TO THE CALLING LEVEL  !N  EXAMPLE OF SUCH A SOFTWARE STRUCTURE IS SHOWN IN &IGURES  AND  4HE SOFTWARE WOULD BE EXECUTED IN THE HARDWARE SHOWN IN &IGURE  &)'52%  -&!2 STRUCTURED SOFTWARE .   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°Ç !N -&!2 CAN SUPPORT MANY ACTIVITIES OR MODES  CONCURRENTLY BY INTERLEAVING  THEIR RESPECTIVE DATA COLLECTIONS 3URVEILLANCE  TRACK UPDATES  AND GROUND MAPS ARE  EXAMPLES OF SUCH ACTIVITIES 4HE SOFTWARE NEEDED TO SUPPORT EACH ACTIVITY IS MAPPED TO A SPECIFIC CLIENT MODULE  AS SHOWN IN &IGURE  %ACH CLIENT MODULE IS RESPONSIBLE FOR MAINTAINING ITS OWN OBJECT DATABASE AND FOR REQUESTING USE OF THE APERTURE 2EQUESTS ARE MADE BY SUBMITTING ANTENNA JOB REQUESTS THAT SPECIFY BOTH THE WAVEFORM TO BE USED HOW TO DO IT  AND THE PRIORITY AND URGENCY OF THE REQUEST ! SCHEDULER EXECUTES DURING EACH DATA COLLECTION INTERVAL AND DECIDES WHAT TO DO  NEXT  BASED ON THE PRIORITIES AND URGENCIES OF THE ANTENNA JOB REQUESTS THAT HAVE BEEN RECEIVED 4HIS KEEPS THE APERTURE BUSY AND RESPONSIVE TO THE LATEST ACTIVITY REQUESTS &OLLOWING THE SELECTION OF THE ANTENNA JOB BY THE SCHEDULER  THE FRONT 
 , vol. 14, pp. 1531–1539, 1975. 
 TYPE SYSTEM ALREADY USED LONG PULSES AND PULSE COMPRES 
 E. Sweeney, “Spatial properties of ionospheric radio propagation as determined with half- degree azimuthal resolution,” Stanford Electron. Lab. 
 MINALS PRODUCE THE SUM AND DIFFERENCE OF THE TWO AMPLIFIED INPUT SIGNALS "ECAUSE  $0#! COMPENSATES FOR THE COMPLEX SIGNAL  BOTH AMPLITUDE AND PHA SE INFORMATION  MUST BE RETAINED 4HEREFORE  THESE OPERATIONS USUALLY OCCUR AT 2& OR )& $IGITAL COMPENSATION CAN BE USED IF SYNCHRONOUS DETECTION AND ANALOG TO DIGITAL !$  CONVERSION ARE PERFORMED AND THE COMPONENTS ARE TREATED AS COMPLEX PHASORS &URTHERMORE  THE OPERATIONS MUST BE LINEAR UNTIL THE SUM SIGNAL AND DIFFERENCE SIG 
 Silicon  point-contact and Schottky-barrier diodes 15•24 based on the nonlinear resistance character­ istic of metal-to-semiconductor contacts have been used as the mixing element.4•5 Schottky­ harrier diodes are made of either silicon or GaAs, with GaAs preferred for the higher  microwave frequencies. The Schottky-barrier diodes have had lower noise figures and lower  flicker noise than conventional point-contact diodes, but the silicon point-contact diode has  had better burnout properties. An integral part or the mixer is the local oscillator. 
 Monmouth, NJ, May 1987, pp. 495–502. ch06.indd   51 12/17/07   2:04:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 FAST BOATS IN $ARWIN  !USTRALIA v  30!7!2 3YSTEM #ENTER 4ECH  2EPT   3EPTEMBER   3 * !NDERSON  h2EMOTE SENSING WITH THE *INDALEE 3KYWAVE 2ADAR v  )%%% * /CEAN %NG   VOL /% 
 14.11. Large Systems Where NoCommercial Power IsAvailable.— Where 24-hour operation ofaprime mover isrequired, itisnecessary to provide duplicate power generation equipment, regular and emergency. Such equipment should beinterchangeable, and the two sets should be used alternately toensure reliable service. 
 Peebles, P. Z., Jr.: Design of a 100:1 Linear Delay Pulse Compression Filter and Sys- tem, master thesis, Drexel Institute of Technology, Philadelphia, December 1962. 20. 
 RANGE SIDELOBES  AND HAVE THE  &)'52%     0HASE VERSUS TIME RELATIONSHIP FOR &RANK CODE OF  LENGTH  -     .   05,3% #/-02%33)/. 2!$!2   n°Ó£ DOPPLER TOLERANCE OF THE ,&- CODES 4HE 0 AND 0 CODES ARE MODIFIED VERSIONS OF  THE &RANK CODE WITH THE $# FREQUENCY TERM AT THE CENTER OF THE PULSE INSTEAD OF AT THE BEGINNING 4HEY ARE MORE TOLERANT OF RECEIVER BAND 
 "ASED !IR $EFENCE n   #OULSDON  3URREY  5+  *ANES )NFORMATION 'ROUP    PP n  2 +LEMM  h.EW AIRBORNE -4) TECHNIQUES v IN  )NTERNATIONAL 2ADAR #ONFERENCE ,ONDON       P   h0AVE MOVER 4!7$3 DESIGN REQUIREMENTS v (UGHES !IRCRAFT 3PECIFICATION  .OVEMBER    UNCLASSIFIED  UNLIMITED DISTRIBUTION  * 0EARSON  h&,!-2 SIGNAL TO NOISE EXPERIMENTS v (UGHES !IRCRAFT 2EPORT .O 0 
 Any use is subject to the Terms of Use as given at the website. Reflector Antennas.  REFLECTOR ANTENNAS  12.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 −1−0.75−0.5−0.2500.250.50.751 −1−0.75−0.5−0.25 0 0.25 0.5 0.75 113 2 13 2 90°Off  Axis FIGURE 12.14  Axial view of 30° tripod strut blockage interference  patternsReflected  wavefrontStrut axisStrut FIGURE 12.13  Strut 1 and maximum scattering cone  −20−15−10−505101520 - -30∞E HStrut 1  - -30∞ Strut 3 Strut 2Reflector   Edge −5Strut 1 30° 0 −10 −20−15 FIGURE 12.12  Center-fed reflector with tripod struts, side view, and axial view ch12.indd   15 12/17/07   2:31:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 September, 1958.  59. It'ehster. 
 Jr .. and R. B. 
 COUPLED TECHNIQUE USES A MICROWAVE HYBRID AND EFFECTIVELY CHANGES THE  DISTANCE AT WHICH THE REFLECTION TAKES PLACE 4HIS TECHNIQUE IS USUALLY USED IN BINARY INCREMENTS  AND AN ADDITIONAL SET OF DIODES IS REQUIRED FOR EACH PHASE STATE 4HE DIODE PHASE SHIFTERS  DESCRIBED ABOVE ARE LIMITED  IN THEIR ABILITY TO HANDLE HIGH  PEAK POWER $EPENDING ON THEIR SIZE AND FREQUENCY  THEY ARE NORMALLY RESTRICTED TO POWER LEVELS OF LESS THAN  K7 &OR HIGHER POWER LEVELS  THE LOADED 
 Figure 13.4 shows two isotropic radiators that are  spaced by a distance s and excited with equal amplitude and phase. With unity input FIGURE 13.3  Aperture distribution giving two beams ch13.indd   9 12/17/07   2:38:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 €   E i=  E hi+  E vi=Exi e x+Eyi e y ( )⋅ejωt+βz ( ) (11.3)   For representing a state of polarization the pola rization ellipse is frequently used, as in Figure  11.2.  It describes a curve, which the real part of the electrical field vector    €   E i(z,t) goes  through, if either the position “z” is held constant (z=constant) and the time “t” runs or the  time “t” is held constant (t=constant) and the position “z” changes.  The angle τ between three - dimensional axes and the semi -major axis of the ellipse is called the rotation angle. 
 Nevertheless, there are cases where building that much equipment weight into the antenna is undesirable, which may force designers to stay with conventional combining schemes. One such case is shipboard radars; the antenna is always mounted as high on the ship as possible, where weight must be minimized to maintain roll stability, and where access for maintenance is extremely difficult.1 Because of the large number of individual modules in a typical solid-state transmitter, failure of an individual or a few modules has little effect on overall transmitter performance. However, the module outputs add as voltage vectors,System ROTHR NAVSPASUR* SPS-40* PAVE PAWSt BMEWS* TPS-59 TPS-59* SEEK IGLOO MARTELLO* RAMP SOWRBALLContractor Raytheon Raytheon Westinghouse Raytheon Raytheon GE GE GE Marconi Raytheon WestinghouseFre- quency, MHz 5-30 218 400-450 420-450 420-450 1200-1400 1200-1400 1200-1400 1250-1350 1250-1350 1250-1350Peak power, kW 210 850 250 600 850 54 54 29 132 28 30Duty cycle CW CW 1.6% 25.0% 30.0% 18.0% 18.0% 18.0% 3.75% 6.8% 4.0%Average power, kW 210 850 4 150 255 9.7 9.7 5.2 5 1.9 1.2No. 
 TYPE TRANSMITTERS WITH A SOLID 
 TO 
  AND HIGHER 
    4HE POWER PASSING THROUGH THE REFLECTOR  OR TRANSMISSION LOSS  CAN BE DETERMINED  USING A HANDY NOMOGRAPH  /NE SELECTS THE GRID SPACING AND THREAD RADIUS TO ACHIEVE  THE TRANSMISSION LOSS REQUIRED 4HE RESULTING LOSS IN ANTENNA GAIN IS TERMED  LEAKAGE  LOSS  AND THE RELATIONSHIP BETWEEN LEAKAGE LOSS AND TRANSMISSION LOSS IS PLOTTED IN &IGURE  FOR A CONDUCTIVE REFLECTOR NO OHMIC LOSSES  4HE LEAKAGE LOSS VS SPACING RELATIONSHIP FOR &IGURE  A CAN ALSO BE COMPUTED USING AN EQUIVALENT CIRCUIT  WITH  SHUNT SUSCEPTANCE  B  DEVELOPED BY -UMFORD   THE SOURCE OF THE NOMOGRAPH  B SE BDS 
 Found. Rept. 1388-13, Jan. 
 Maisel42 © IEEE 1968 ) ch24.indd   12 12/19/07   6:00:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 Thus, the elevation sidelobes protecting the radar upper beams from ground or sea clutter are the (one-way) elevation re- ceive sidelobes. This is true because the transmit beam main lobe must be broad enough in elevation to cover all receive beams. This is different from the scan- ning pencil-beam radar, in which the product of the transmit and receive eleva- tion sidelobes protects the radar upper beams from surface clutter. 
 *-Ê, ,Ê -* 9- "Y DEFAULT  THE RESULTS OF THE PROPAGATION MODEL CALCULATIONS ARE SHOWN IN TERMS APPRO 
 WEIGHT  -4) AND OPTIMUM -4) AGAINST A GAUSSIAN 
 Filters are the main source of amplitude and phase ripple across the signal  bandwidth as other components such as amplifiers and mixers are typically rela - tively broadband. The degree of tracking required for sidelobe canceler operation  was previously achieved by providing matched sets of filters with tightly tracking  amplitude and phase responses. Modern digital signal processing allows the correc - tion of these channel-to-channel variations using FIR equalization (Section 6.11) or  correction in the frequency domain in the digital signal processor, allowing the use  of less tightly controlled filters. 
        
 !RRAY 2ADARS   )N THIS SUBSECTION  WE ILLUSTRATE  BY A NUMERICAL EXAM 
 302  - 3TREETLY   2ADAR AND %LECTRONIC 7ARFARE 3YSTEMS   n  TH %D  #OULSDON  3URREY  5+  *ANES )NFORMATION 'ROUP    PP n  2 .ITZBERG   2ADAR 3IGNAL 0ROCESSING AND !DAPTIVE 3YSTEMS   .ORWOOD  -! !RTECH (OUSE     PP n  n  n  7 + 3AUNDERS  h#7 AND &7 RADARv & - 3TAUDAHER  h!IRBORNE -4)v 7 ( ,ONG    $( -OONEY  AND 7 ! 3KILLMAN  h0ULSE DOPPLER RADARv 2 * 3ERAFIN  h-ETEOROLOGICAL RADAR v  2ADAR (ANDBOOK  ND %D  - 3KOLNIK ED   .EW 9ORK -C'RAW (ILL    PP n  n  n  n  0 ,ACOMME  * 
 ARRAY  SYSTEMS AND TECHNOLOGIES IN !-3 v  )%%% )NT 3YMP ON 0HASED 
 McGraw-Hill Book Co., New York, 1970.  3 1. Locke, A.6.: "Guidance," D. 
 , ae range of the aircraft fom o ie bere  been d ined the en ground beacons has eterminet Ton, 1onerm  obtained. In addition to knowing its p% a er,  an aircraft requires to know its ems . a  ‘nitude and direction, before b0 ee  ae blindly that they will hit the _ Sir Ri lar  information is equally necessary for #* 4. 
  AND 2ANGE 2ATE !MBIGUITY 2ESOLUTION  4O APPLY THE 36# ALGORITHM   TRUE RANGE AND RADIAL VELOCITY RANGE 
 The sea state is a measure o(the wave height, as shown in Table 13.l. Although the sea  state is commonly used to describe radar sea-clutter measurements, it is not a complete  measure in itself since, as 'mentioned above, the radar sea echo depends on many other factors.  Sea clutter is also sometimes described by the wind speed, but likewise it is not a suitable  measure by itself. 
 OUS INTEGRATION  THE EFFECTIVE NUMBER OF INDEPENDENT SAMPLE IS  &)'52%     3PECTRUM OF FADING FROM A HOMOGENEOUS SMALL PATCH   A  BEFORE AND B  AFTER DETECTION. 
 TO 
 5 of "Radar Handbook," M. I. Skolnik (ed.). 
 A properly designed radome should distort the antenna pattern as little as possible. The  presence of a radome can affect the gain, beamwidth, sidelobe level, and the direction of the . RADAR ANTENNAS 265  horesight (pointing direction), as well as change the VSWR and the antenna noise tempera­ ture. 
 Rossi, and C. J. Koblinsky, “Prelaunch performance of the NASA  altimeter for the TOPEX/Poseidon Project,” IEEE Transactions on Geoscience and Remote  Sensing , vol. 
  
 75 CHO 938-1 AES.  22. Zvcrcv, A. 
 Jackson, “The geometry of bistatic radar systems,” IEE Proc ., vol. 133, pt. F, pp. 
 134-139.  23. Dahlsjo, 0.: A Low Side Lobe Cassegrain Antenna," Radar--- Present and Future," Oct. 
 (2.57). Reducing scan time (increas­ ing rotation rate) requires an increase in the average power and;or antenna size. Some long­ range military radars have rotation rates of 15 rpm (4-s scan time) because of the likelihood  of target maneuver. 
 The multiple beams may be fixed in space, steered indepen­ dently, or steered as a group (as in monopulse angle measurement). The multiple beams might  be generated on transmit as well as receive. It is convenient in some applications to generate  the multiple beams on receive only and transmit with a wide radiation pattern encompassing  the total coverage of the multiple receiving beams. 
 The Air Force Cobra Dane phased-array radar, for examplt.:, uses 96  /Gun Attenuation  Cathode Lade ,@rn, Collecto~  Heater~-~----~-----~ --- ------1· · Helix · •  Elewon gr l t ::::: I I  beam t RF . RF  input. output  Figure 6.11 Diagrammatic representation or the traveling-wave tube. 
 I Frequency  modulator TR +  L Transmitter -  422INTRODUCTION TORADAR SYSTEMS Thereareatleasttwowaysofdescribing theconcept ofapulse-compression radar.Oneis basedonanapproach similartothatoftheambiguity function ofSec.11.4.Amodulation of someformisapplied tothetransmitted waveform anditsresponse afterpassingthrough the matched filterisexamined. Forexample, thefrequency-modulated pulsewaveform whose ambiguity diagram wasshown inFig.11.12isthewidelylIsedchirppulse-compression waveform. Theotherapproach istoconsider themodulation applied toalongpulseas providing distinctive marksovertheduration ofthepulse.Forinstance, thechanging frequency ofalinearly frequency-modulated pulseisdistributed alongthepulseandthus identifies eachsegment ofthepulse.Bypassing thismodulated pulsethrough adelayline whosedelaytimeisafunction ofthefrequency, eachpartofthepulseexperiences adifferent timedelaysothatitispossible tohavethetrailingedgeofthepulsespeeded upandtheleading edgesloweddownsoastoeffectatimecompression ofthepulse. 
 pp. 427 463. Mnrcll. 
 causing the phase shift of the beat signal to vary cyclically with time. The indicating  system was designed so that it did not respond to the 10-Hz modulation directly, but it caused  the fixed error to be averaged. Normal fluctuations in aircraft altitude due to uneven terrain,  waves on the water. 
 RAY LEVEL  AND SUPERRESOLUTION 4HE IMPLEMENTATION OF THE ADAPTIVE ARRAY CONCEPT IS MORE AND MORE RELATED TO DIGITAL BEAMFORMING n AND TO DIGITAL ARRAY RADAR $!2   TECHNOLOGIES  *AMMER #ANCELLATION AND 4ARGET 3IGNAL %NHANCEMENT  !DAPTIVE ARRAY PRIN 
 ITED TO ABOUT  KM NORTH 
 Thecondition givenbyEq.(14.13),and similarrelations, represent anupperboundonthecapabilities ofanSARtoachievearesolu­ tionc5croveraswathS.... Radarequation forSAR.Eachparticular application hasitsownformoftheradarequation. TheSARhasaparticularly interesting form,especially whentherelationships derivedahove aretakenintoaccoun!. 
 PLE TRIP  ECHOES   AND TO COMPUTE DEALIASED VELOCITIES IN THE RANGE DEALIASED  ECHOES TO CLASSIFY AND SEPARATE PRECIPITATION ECHOES FROM ARTIFACTS AS GROUND CLUT 
 Figure 10.32 shows agroup ofhigh-vacuum switch tubes; Table 10.4 gives aset oftypical operating characteristics. Except forthescreen-grid and control-grid bias requirements ofpower output and driver stages, thehard-tube pulser israther simple, for(asis shown inFig. 10.33) thegrid-driving circuit isnotinherently complicated. 
 In 1939 the Army developed the SCR-270, a long-range radar for early warning. The attack  on Pearl Harbor in December, 1941, was detected by an SCR-270, one of six in Hawaii at the  time.1 (There were also 16 SCR-268s assigned to units in Honolulu.) But unfortunately, the  true significance of the blips on the scope was not realized until after the bombs had fallen. A  modified SCR-270 was also the first radar to detect echoes1 from the moon in 1946. 
 T. A. Seliga and V . 
 Notable examples are the NATO air defense trials2,113,114  and the University of Washington’s Manastash Ridge Radar  measuring ionosphere  turbulence2,48—both passive bistatic radars exploiting FM broadcast transmitters;  the HDTV-Based Passive Radar  exploiting a high definition-TV broadcast transmit - ter for air surveillance2,51; the inexpensive, commercial bistatic receiver hitchhiking  off weather radars to measure full vector wind fields 2,42; and the bistatic radar for  weapons location.35 Furthermore, major progress has been made in developing signal and data process - ing algorithms, including bistatic SAR autofocus and image formation and space-time  adaptive processing for bistatic airborne MTI (see Section 23.5). However, two prob - lems continue to plague bistatic and multistatic radars and have become the topics  of this section: (1) beam scan-on-scan for bistatic radars and radar hitchhikers and   (2) noncooperative RF environments for passive bistatic radars. These problems and  their potential remedies are detailed next. 
 Owen,  “Dual-use  shipborne phased array radar technology and tactical environmental sensing ,” in Proc. IEEE  National Radar Conf. , Atlanta, 2001, pp. 
 A constant phase shift can be inserted in the path  to each element, with a value that differs from element to element by amounts that are  unrelated to the bit size. This added phase shift is then subtracted in the command sent to the  phase shifter. With an optical-fed array, such as the reflectarray or the lens array, decorrela­ tion of the phase quantization is inherent in the array construction. 
 BIT !$# TYPICALLY HAS AN %./" OF  7ITH THE BANDPASS SAMPLING TECHNIQUE DESCRIBED EARLIER  WHERE THE !$# CAN SAM 
 Figure 24.6/? is for nighttime. All the curves are the same as in Fig. 24.6« except for atmospheric noise. 
 Thus oil slicks  appear dark on a radar PPI compared to the surrounding sea and are readily detectable.  High~resolution X-band radar, for example, can sometimes detect the oil leaking from the  engine of a small boat at anchor, Airborne synthetic-aperture radar has been demonstrated to  locate and map oi\ slicks over a large area. It is found that vertical polarization produces  higher contrast than horizontal polarization. 
 CLUTTER RATIO SEEN BY EACH RADAR IS PROPORTIONAL TO THE SIZE OF THE RADAR RESOLUTION CELL AND MAY BE A FUNCTION OF FREQUENCY 4HUS  A RADAR WITH A  
 100. B. A. 
 AP-13, pp. 823 824, September, 1965.  119. 
 3HALOM  h4RACKING MANEUVERING TARGETS WITH MULTIPLE SENSORS $OES MORE  DATA ALWAYS MEAN BETTER ESTIMATES v  )%%% 4RANS !EROSPACE AND %LECTRONIC 3YSTEMS   VOL     PP  
 .. JI . Till' 1'.I.ITIHONH"AI.I.Y STl'FRED l'IIASED ARRAY ANTENNA IN RADAR 317  In principle, multiple receiving beams can be generated utilizing the Fast Fourier Trans­ form (FFT) processor.159 If the output of each receiving element is sampled at the Nyquist  rate and if the sampled voltages are converted to a digital number, the FFT processor may be  used to generate multiple beams digitally, just as the Butler beam-forming array generates  them in analog fashion. 
 Finally, these processors are generally used for non-real-time  or near-real-time data processing, as in target tracking and display processing. Since  the 1990s, they have started to be applied to real-time signal processing applications.  Although they might be cost-effective for relatively narrowband systems, their use in  wideband DSP systems in the early 21st century is typically prohibitively expensive  due to the large number of processors required. 
 DOMAIN REPLICA OF THE SIGNAL !LL '02S MAY HAVE TO DETECT SIGNALS FROM A TARGET THAT MAY BE n TO n D"  LOWER THAN THE RADIATED SIGNAL AT RANGES IN THE ORDER OF A METER  NS IN FREE SPACE  )N ADDITION  THE RECEIVED SIGNAL WILL CONTAIN TEMPORAL SCATTERING INFORMATION ON THE TARGET THAT CAN BE EXPLOITED 4HE TEMPORAL FIDELITY OF RECEIVED SIGNAL NEEDS TO BE PRESERVED AND THUS DESIGNERS OF  '02 HAVE TO ENSURE THAT THE RECEIVER IS NOT SATURATED BY THE TRANSMITTED SIGNAL  THE ANTEN 
 81, pp. 194–204, 2002. 178. 
 LINE FILTERS WITH OR WITHOUT FEEDBACK  ARE SYNTHESIZED ON THE BASIS OF STOPBAND REJECTION 4HE LIMITING CASE IS THE NARROWBAND FILTER BANK WHERE EACH INDIVIDUAL FILTER CONSISTS OF A SMALL PASSBAND  THE BALANCE BEING STOPBAND )MPROVEMENT FACTOR IS AN IMPORTANT METRIC  BUT IN ADDITION TO THIS AVERAGE METRIC  DEFINED ACROSS ALL DOPPLER FREQUENCIES   IT IS OFTEN IMPORTANT T O CHARACTERIZE THE PERFOR 
 For input signals at frequencies f1 and f2, second order intermodulation distortion  produces signals at frequencies: 0, f 1 – f 2, f 1 + f2, 2f1 and 2 f2. Third order intermodu - lation distortion produces signals at frequencies: 2 f1 – f2, 2f2 – f1, 2f1 + f2, f1 + 2f2, 3f1  and 3 f2. For narrow band signals, only the third order products 2 f1 – f2 and 2 f2 – f1 fall  in band, and consequently, third order distortion is typically the primary concern. 
 8.29). Each r~iixer is supplied with a different LO frequency. 'The trarismitting antenna  provides a single bearn illurniriating the coverage of the N receiving beams. 
 The electrical scan isaperiodic time variation inthe direction ofthe energy falling upon the reflector. The antenna’ about 1R.M.Robertson, ioc.auf. 2H.A,Straus, “Brief Description ofAN/TPG-1, AN~FPG-1, SCR-598,” RL Report No.456, Oct. 
 However, high-medium PRFs have inherently good doppler  visibility (since they are ambiguous in sign only), so the span of the PRFs in a set of  N PRFs is usually much less than an octave. Additional constraints on PRF selection  for both waveforms include good visibility in sidelobe clutter (where some PRFs may  be obscured by clutter in portions of the ambiguous range interval) and minimization  of ghosts in the ambiguity resolution processing. Doppler Ambiguity Resolution. 
 Am.  Meteorol. Soc. 
 It is difficult, however, to prevent diffraction of radar energy from the top of the  fences from reaching the target or to prevent target-diffracted signals from reaching  the radar receiver via the same kind of mechanism. Because of the large distances from the radar to the target on outdoor ranges, instru - mentation radars at one time developed peak signal powers ranging from 1 to 100 kW.  ch14.indd   31 12/17/07   2:47:25 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 BAND INTERFERENCE TO OTHER RADARS 4HUS  THE #%! PROBABLY SHOULD BE A CANDIDATE WHEN CONSIDERING ANY NEW 5(& RADAR SYSTEM  AS WELL AS RADARS AT LOWER FREQUENCIES  ESPECIALLY IF MUTUAL INTERFERENCE IS A POTENTIAL PROBLEM -AGNETRON )T WAS MENTIONED THAT THE MAGNETRON WAS WHAT MADE MICROWAVE  RADAR POSSIBLE IN THE S 4HE MAGNETRON IS STILL A VALID CANDIDATE FOR SMALL  NON 
     PP n  *ULY   2 -ITCHELL ET AL  h-EASUREMENTS OF PERFORMANCE OF -)0)2 -ISSILE 0RECISION )NSTRUMENTATION  2ADAR 3ET !.&01 
 3. WASAR Imaging Based on LS-CS-Residual L1regularization would cause the errors of the amplitude and support set estimation in WASAR imaging. In this section, we propose a novel WASAR imaging based on LS-CS-Residual. 
 valueofthevoltagesquared.Ifx2isreplaced oyw,wherewrepresents powerinstead ofvoltage(assuming theresistance is1ohm),Eq.(2.17)becomes 1(w) p(w)=----exp----- Wo WoW;:o::O (2.18) where \\'0istheaverage power.Thisistheexponential probability-density function, butitis sometimes calledtheRayleigh-power probability-density function.ItisplottedinFig.2.2d. Thestandard deviation oftheRayleigh densityofEq.(2.17)isequaltoJ(4/n)-1timesthe meanvalue.andfortheexponential densityofEq.(2.18)thestandard deviation isequaltowo. Thereareotherprobaoility-density functions ofinterestinradar,suchastheRice,lognormal, andthechisquare.Thesewilloeintroduced asneeded. 
 12.2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 dramatic T/R module cost reductions and technology improvements. The improved per - formance of ESA radars is cited as a reason for decreased utilization of reflector antennas  in many of today’s radar system designs. However, there are still applications where the reflector antenna is well suited to radar  applications and will continue to find applications in the future. 
 5.3. Monte-Carlo Simulation As is mentioned before, the phase and amplitude scintillation is a random process. Therefore, the Monte-Carlo simulation is required to perform a statistical analysis. 
 In addi - tion, the A/D converter input signal noise bandwidth may be significantly less than the  Nyquist bandwidth. This is a significant factor in IF sampling applications where the  IF noise bandwidth is often less than ¼ of the Nyquist bandwidth. In this case, the total  input and A/D converter noise must be sufficient to whiten the quantization noise, and  the power spectral density of the input noise should be sufficiently greater than that of  the A/D converter, as illustrated in Figure 6.16. 
 MIN AVERAGING 0ERFORMANCE  -ODELING  %XAMPLES OF (&372 SYSTEM PERFORMANCE MODEL 
 TO 
 Two incoherent sources separated by a quarter beam width seem to be the lower limit for superresolution with the current technology for achieving equality between the channels, offset compensation, equality of / and Q channel amplifica- tion, etc. Resolution is worse for more than two sources.58 9.7 TRANSMITTER-RELATED ECCM The different types of ECCM are related to the proper use and control of the power, frequency, and waveform of the radiated signal. One brute-force ap- . 
 TARGET GEOMETRIES A   NEAR END ON  B  n ASPECT ANGLE   AND C  BROADSIDE !LL THREE BISTATIC REGIONS ARE SHOWN IN THE FIGURE )N THE BROADSIDE  GEOMETRY  THE PSEUDO 
 Also, the matched filter bandwidth and associated noise  power decreases inversely with t. If the radar pulse volume is filled with distrib - uted meteorological scatterers, then the radar cross section of the weather target also  increases with t (as determined by Equations 19.9 and 19.12) and the signal-to-noise  ratio (SNR) of received power is proportional to t2:  P P T B Tr n∝ ≈τ κτ κ2  (19.27) Thus, under these common conditions increasing the pulse length will increase the  SNR and the effective radar range. It is important to note that the distributed target  radar dependence of SNR on t2 is different from the point target radar in which the  matched filter SNR equals the ratio of pulse energy to noise spectral density (2 E/N0 =   2Pt t /N0), a linear dependence on t. 
 Weiner, M. M., and P. D. 
 SIDEBAND NOISE CAN BE TRANSLATED TO A SINGLE 
 Khorshidi, S.; Karimi, M.; Nematollahi, A.R. New autoregressive (AR) order selection criteria based on the prediction error estimation. Signal Process. 
 for a pub  doppler AMTI radar. ( After M aquire, 70 Proc. Natl. 
 Experimental analysis of soft soil characteristics in Wuhan. Resour. Environ. 
 (Theamplitude N isnormalized bydividing theoutputofeachtapbythesquarerootofLwl,where /'"I. 112 INTRODUCTION TO RADAR SYSTEMS  1 Frequency  Figure 4.12 Amplitude responses for three MTI delay-line cancelers. (1) Classical three-pulse canceler,  (2) five-pulsedelay-linecanceler with "optimum" weights, and (3) 15-pulse Chebyshev design. 
 LIMITED DETECTION ARE DESCRIBED IN SOME DETAIL 4HE .2, 
 The coherent detector is an example of one which uses both phase and amplitude.  These three types of detectors-the envelope, the zero-crossings, and the coherent detectors- !  are considered in the present section.  Envelope detector-optimumdetector law. 
 17 .2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 l divided by the aperture diameter: qB ≈ l  /D. The corresponding linear crossrange  resolution at range R is then  δλ cr≈R D  (real aperture) (17.1) For example, if l = 3 cm (X band) and D = 2 m, qB ≈ 0.015 radians. At a range of R =  100 km, the crossrange resolution would be R qB ≈ 1.5 km, hardly fine enough to resolve  such targets as buildings and vehicles. 
 TROL EFFECTIVELY ALTERS THE DETECTION THRESHOLD /N A MODERN MARINE RADAR  THE SEA 
 Gelb, Applied Optimal Estimation , Cambridge, MA: MIT Press, 1974. 54. F. 
 FORM TO OBTAIN A RANGE MEASUREMENT (273 AND !LERT#ONFIRM WAVEFORMS ARE FOLLOWED BY RANGE GATED HIGH 
 ,- !PPLICATIONS ,IMITERS ARE USED TO PROTECT THE RECEIVER FROM DAMAGE AND TO CON 
 Intheir design every effort has been made toachieve the optimum inresolution, light intensity, deflection sensitivity, and com- pactness. The materials (phosphors) used inthescreen areofparticular importance. If,asisusually thecase, thescanning interrupts thepicture forlonger than theretentivity time oftheeye, itisnecessary tointroduce persistence into the screen. 
 .. 520 THERECEIVING SYSTEM—INDICATORS [SEC. 13.12 the sawtooth generator are the delay potentiometer and itsassociated resistors and the diode V5.The circuit isdescribed indetail inChaps. 
 &- SLOPE MAGNITUDE  2MAX   MAXIMUM INSTRUMENTED RANGE.   05,3% $/00,%2 2!$!2   {°{x !LERT#ONFIRM INCREASES SENSITIVITY BY ALLOWING MORE FALSE ALARMS IN !LERT AND RELY 
 For example, the cathode is outside the RF  field and need not be restricted to sizes small compared with a wavelength. Large cathode area  and large interelectrode spacings may be used to keep the emission current densities and  voltage gradients to reasonable values. The only function of the collector electrode in the  klystron is to dissipate heat. 
 The transmitter, receiver, duplexer, and phase shifters for each  element of the array antenna can be incorporated into a single integrated package, or module.  Although there has been much development work in solid-state phased arrays with each  element fed by its own integrated module, this approach usually results in a costly and  complex system. This has tended, in the past, to weigh against the widespread use of such  phased-array radars when the number of elements is large. 
 If the output is definitely below the lower threshold, noise alone  is said to he present. If the upper threshold is exceeded, the signal is declared to be present  along with the noise. But if the output lies between the two thresholds, no decision is possible  and anol her ohserv a I ion is nrnde. 
 POINTING ACCURACY 0HASE %RRORS 4HE PHASE OF A PHASE SHIFTER HAVING  0 BITS CAN BE SET TO THE DESIRED  VALUE WITH A RESIDUAL ERROR   0EAKPHASEERROR    oAP 0     2-3PHASEERROR   SP F0   ,OSS IN 'AIN !S DISCUSSED IN 3ECTION   THE LOSS IN GAIN IS  SF  WHICH WITH  %Q  GIVES   $'0y SP F      7ITH MANY ARRAY ELEMENTS  THIS RESULT IS STATISTICALLY INDEPENDENT OF THE AMPLITUDE  DISTRIBUTION !N ENUMERATION OF %Q  GIVES  .UMBEROFPHASE 
  
 SORS PERMITS TAILORING OF THE PROCESSORS CHARACTERISTICS TO THE APPLICATION FROM DAY TO DAY OR EVEN BEAM TO BEAM AND GATE TO GATE. £°ÓÓ  2!$!2 (!.$"//+  -EASUREMENT !CCURACY  "ECAUSE THE RECEIVED SIGNALS ARE SAMPLE FUNCTIONS  FROM GAUSSIAN RANDOM PROCESSES  THE DOPPLER SPECTRUM AND ITS MOMENTS CANNOT BE  MEASURED EXACTLY IN ANY FINITE PERIOD OF TIME #ONSEQUENTLY  ALL MEASUREMENTS WILL BE SOMEWHAT IN ERROR  WITH THE ERROR BEING A FUNCTION OF THE PROPERTIES OF THE ATMOSPHERE  THE RADAR WAVELENGTH  AND THE TIME ALLOCATED TO THE MEASUREMENT 4HE THEORETICAL DEVELOPMENT OF SIGNAL ESTIMATOR STATISTICS IS FOUND IN $ENENBERG   3ERAFIN  AND 0EACH  FOR THE &&4 TECHNIQUE $OVIAK AND :RNIC ` COVER THE SUBJECT QUITE  COMPLETELY WHILE +EELER AND 0ASSARELLI PROVIDE A GOOD SUMMARY OF ALL THESE ESTIMATION  TECHNIQUES AND THE RESPECTIVE MEASUREMENT ERROR EXPRESSIONS &OLLOWING ARE SOME USE 
 Another end- fire array isthe Yagi antenna. Commonly, this isanarray ofdipoles, only one ofwhich isexcited bythetransmission line; behind itisapara- sitic reflector dipole and infront areseveral parasitic director dipoles. The. 
 3URFACE $ESCRIPTORS 3EA 3TATE 7IND 3PEED  KT 7AVEHEIGHT (  FT$URATIONFETCH  HNMI  SMOOTH          SLIGHT  n   n     MODERATE  n   n  ROUGH  n   n  VERY ROUGH  n  n  HIGH  n n   VERY HIGH  n n . 
 Measurements can be obtained with scale models on a  pattern range.19 An example of such model measurements is given by the dashed curves in  Fig. 2.17. If care is taken in the construction of the model and in the pattern-range  instrumen tat ion, it is possible to achieve reasonably representative measurements. 
 PATH AND SYSTEM LOSSES  2     DISTANCE BETWEEN RADAR AND TARGET. Óä°È  2!$!2 (!.$"//+  4HESE PARAMETERS ARE EXPLAINED BRIEFLY AS FOLLOWS !NTENNAS  'T AND 'R  ! COMMON CONVENTION FOR (& 
 OUSLY  THE  
 SCAN PROBABILITY OF DETECTION BECOMES WORSE &IGURE  SHOWS THE IMPROVEMENT FACTOR LIMITATION DUE TO SCANNING FOR CANCELERS  WITH FEEDBACK 4HESE CURVES WERE CALCULATED ASSUMING A SIN  5 5 ANTENNA PATTERN  TERMINATED AT THE FIRST NULLS  4HE NO 
 2.14 ADAPTIVE MTI When the doppler frequency of the returns from clutter is unknown at the radar input,  special techniques are required to guarantee satisfactory clutter suppression. As dis - cussed in Section 2.10, the doppler filter bank will usually be effective against moving  clutter. This requires that the individual filters be designed with a low sidelobe level  in the regions where clutter may appear and that each filter be followed by appropri - ate CFAR processing circuits to reject unwanted clutter residue. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 equal amplitude and antisymmetric phase to give a difference pattern. The steering  increment is shown to be  δ θq=9 2NPB(scanned)  Periodic Errors Periodic Amplitude and Phase Modulation . 
 EMITTER JUNCTION IS REVERSE 
 Indeed, the essence of Sir  Robert Watson-Watt’s discovery seemed at first to be  that radar, distinct from any other form of position-  finding, needed no co-operation on the part of the target.  A chain of coastal, and subsequently, inland warning  radar stations was erected the major purpose of which  was to detect and locate a target without the target  being made aware of the invisible radar beam tracking  it through clouds and in dark of night.  To-day radar is not confined to systems where the  echo from a radio pulse of energy is used. 
 The early developments of pulse radar were primarily concerned with military applica­ tions. Although it was not recognized as being a radar at the time, the frequency-modulated . THE NATURE OF RADAR 11  aircraft radio altimeter was probably the first commercial application of the radar principle. 
 Ihrton. I). K., ~ntl S. 
 CONS ARE USED ON ROCKETS AND SPACE VEHICLES TO PROVIDE SUFFICIENT SIGNAL LEVEL AT VERY LONG RANGES 4O PREVENT THE TARGET ECHO FROM BEING BLANKED BY A TRANSMIT PULSE  IT IS NECESSARY  TO SENSE WHEN THE TARGET IS APPROACHING AN INTERFERENCE REGION AND SHIFT THE REGION 4HIS IS ACCOMPLISHED BY CHANGING THE 02& OR ALTERNATELY DELAYING GROUPS OF PULSES EQUAL TO THE NUMBER OF PULSES IN PROPAGATION 4HIS CAN BE PERFORMED AUTOMATICALLY TO PROVIDE AN OPTIMUM 02& SHIFT OR TO ALTERNATELY DELAY PULSE GROUPS OF THE CORRECT NUMBER OF PULSES °ÈÊ -* 
 . RANGING USED IN -273 REQUIRES CORRELATION IN RANGE AND CAN BE VIEWED  AS A BINARY DETECTOR -273 IS TYPICALLY A MEDIUM 
   WAVE EFFECTS ARE INCORPORATED ANALYTICALLY THROUGH THE 0HILLIPS EXPRESSION FOR THE  DENSITY OF BREAKING FRONTS AS A FUNCTION OF WIND SPEED THE PARAMETER  ,C  NOTED  IN 3ECTION    WITH THE SCATTERING BEHAVIOR BASED ON 7ETZELS PLUME MODEL SEE  h3CATTERING BY 3URFACE &EATURESv  4HE RESULT IS A SIGNIFICANT IMPROVEMENT IN SEA  SCATTER PREDICTIONS  EMPHASIZING THE IMPORTANCE OF BREAKING IN THE SCATTERING SCENE !N EXAMPLE OF THIS IMPROVEMENT IS SHOWN IN &IGURE   WHERE EXPERIMENTAL DATA FOR THE POLARIZATION RATIO RELATIVE TO WIND DIRECTION WAS OBTAINED FROM THE 0OLRAD  PROGRAM  /NE OF THE MAJOR CLAIMS FOR "RAGG MODELS HAS BEEN THEIR APPARENT ABIL 
 Bothtransmission andreception are accomplished ateachposition. Aclusteroffivefeedsmightalsobeemployed, withthecentral feedusedfortransmission whiletheouterfourfeedsareusedforreceiving. High-power RF switches arenotneededsinceonlythereceiving beams,andnotthetransmitting beam,are stepped inthisfive-feed arrangement. 
 24, pp. 36–42, 1998. 159. 
 Spiral eddies in the baltic, black and caspian seas as seen by satellite radar data. Adv. Space Res. 
 E., and R. A. Ross: Radar Cross Section of Targets, chap. 
 2. R. J. 
 MENTS v IN #ONF 2EC %ASCON   3EPTEMBER   PP n  " 7ALSH  h!N EAGLE IN THE SKY v  #OUNTERMEASURES4HE -ILITARY %LECTRON -AG   PP n   *ULY    $ 2 #AREY AND 7 %VANS  h4HE 0!42)/4 RADAR IN TACTICAL AIR DEFENSE v  -ICROWAVE *  VOL    PP n  -AY . £{°£,>`>ÀÊ ÀÃÃÊ-iVÌ 
 The archi - tecture of these emerging systems is dominated by one of two antenna paradigms:  active two-dimensional phased arrays or reflectors. Most missions are multimode in  resolution (hence swath and coverage), and polarimetry (ranging from incoherent  dual-polarization to full-quadrature polarimetry). At least four of these initiatives  imply several satellites, either in constellation or in series. 
 DIGITAL !$  CONVERTERS AND TO THEIR FREQUENCY AND DYNAMIC 
 Thus the added complexity of higher-order cancelers is seldom justified in such  situations. The linear analysis of MTI signal processors is therefore not adequate when limit-  ing& employed and can lead to disappointing differences between theory and measurement of  actual systems.  Limiters need not be used if the MTI is linear over the entire range of clutter signals and if  the processor has sufficient improvement factor to reduce the largest clutter to the noise level. 
 Wakimoto and R. Srivastava (eds.), Meteorological Monograph, vol. 30, Boston: AMS,  2003, pp. 
 Frequency-domain doppler filter­ banks are of interest in some forms of MTI and pulse-doppler radar.  Filter characteristics of the delay-line canceler. The delay-line canceler acts as a filter which  rejects the d-c component of clutter. 
 40. R. Vigneri et al., “A graphical method for the determination of equivalent noise bandwidth,”  Microwave Journal , vol. 
 (b)R-flocking byoscillator, i-faddition.. f?iEc. 16.4]ALTERNATIVE METHODS FOROBTAINING COHERENCE 637 Taking allpossible combinations, weget23different types ofcircuit. 
 1971.  28. Sclileher. 
 Fulghum, “Future radar,” Aviation Week and Space Technology , October 4, 2004. 21. M. 
 The different responses to different polarizations of the electromagnetic wave  provide information on the target symmetry. It is this property that permits echoes from  ~ymmetrical raindrops to be discriminated against in favor of echoes from asymmetrical  aircraft. Many microwave radars use circular polarization for this purpose. 
 STAGE #)# DECIMATION FILTER  AND ITS FREQUENCY RESPONSE BEFORE AND AFTER DECIMATION BY  IS SHOWN IN &IGURE  A AND B  RESPECTIVELY  .OTE THAT THE ALIASED COMPONENTS ARE SIGNIFICANTLY REDUCED IN AMPLITUDE  COMPARED TO THE SINGLE 
 It is appreciated, however, that sometimes the  marketing manager’s opinion has to prevail if the company is to remain in business. A number of different RF power sources have been considered that, at one time or  other, have been employed in radar. Not all might be popular or desired at some partic - ular time but most should be considered, even if briefly, by the radar system designer  when trying to determine a new radar system design or an upgrade of some existing  system. 
 Aperture Radar Technol. Conf., Pap. VI-4, pp. 
 (after R. K. Moore, K. 
 Wang, A. J. Illingworth, E. 
 159. Ruvin, A. E., and L. 
 In the experiment, select two groups of data with the adjacent pitch angle of 42◦and 42.07◦to divide the whole aperture into 17 sub-apertures. Speciﬁc parameters are shown in Table 3, and Figure 10shows the CAD model of Backhoe. T able 3. 
  
 Presentation ofa200-mile range was desirable, giving atime interval of2140 psec forthesweep. Anadditional 360 psec was added forindica-. SEC. 
 level ofthe probability distribution. The average signal Swill thus be proportional tothe area A,but itcan also beexpected todepend on the aspect angle 8,inaway which need not bespecified here beyond lSpecifically, werequire that thewave trains received from theindividual scat- terers within thetarget area should combine inrandom phase, which willbethecase iftheranges I?itothescattering objects aredistributed with arandomness ordevia- tionmuch greater than onewavelength, over arange interval ARitself much greater than onewavelength.. 88 PROPERTIES OFR.41~.lRT.-lRGE~,~ [SEC. 
 ETCHED GRATING TO DETERMINE ITS BANDPASS CHARACTERISTICS &IGURE  SHOWS THREE TYPES OF FILTER DETERMINATION APPROACHES ! WIDEBAND INPUT TRANSDUCER AND A FREQUENCY 
 F. J., and N. J. 
 This theorem permits bistatic cross sections to be determined from mono-  static cross sections provided the conditions under which the theorem is valid are met.  It may be concluded from the above theorem that as long as P # 180" the rouge ofvalues  of bistatic cross section for a particular target will be comparable with the ratye of values of  monostatic cross section. This does rlot necessarily imply that a monostatic radar and a  bistatic radar viewing the same target 'will see the same cross section. 
 Ashmead, J., and A. B. Pippard: The Use of Spherical Reflectors as Microwave Scanning Aerials, J. 
 WAVE TUBES 4HE LARGER SIZE OF THE FAST 
 Provide a response of —46 dB for chaff rejection at velocities between ±20 percent of the ambiguous doppler frequency range. 3. Owing to hardware limitations, only five filters will be implemented. 
 35. Zeiler, M.D.; Fergus, R. Visualizing and understanding convolutional networks. 
 As will be seen below, this aver- age is about 2 to 3 dB smaller than the upwind returns. Moreover, the early NRL 4FR data was used liberally in the older data summaries, and it was noted above that there is a difference of 3 to 4 dB between the early and later presentations of the same NRL 4FR data, the latter being used in Fig. 13.3a and b. 
 Mueller, “Dual wavelength radar hail   detection,” Bull. Amer. Meteor. 
 15.8. Choice ofBeam Shape. Azimuth Beamwidth.—The merits of anarrow beam aresowidely understood that they will not bediscussed indetail here. 
 The ionosphere is not a benign propagation medium. As the amount of ionization  changes, the optimum frequency for propagating energy to a particular distance must be  changed accordingly. The losses in propagating through the ionosphere change with time, and  the transmitter must have sufficient excess power to overcome the maximum loss expected. 
 54. Betts. F .. 
 There are a number of models that have been proposed to describe the equilibrium  spectral form, and indeed, models that attempt the more ambitious task of modeling  nonequilibrium spectra. Most of these models are based on experimental measure - ments, illustrated here by Figure 20.12, which shows an example of the frequency  spectrum derived from wave buoy measurements. A common feature of such wave  spectra is that waves of a given wavelength tend to reach a limiting spectral density,  beyond which the processes of dissipation and nonlinear transfer of energy to other  wavenumbers prevents further growth. 
 27–32, 1962. 42. R. 
 22.3 of the first edition of this handbook. At high elevation pointing angles, where the errors are due only to surface re- flections from the negative elevation-angle sidelobes, the errors contributed by various sidelobe levels in simultaneous amplitude comparison and phase compar- ison radars may be summarized approximately as follows: 0.2 to 0.3 beamwidth, when the surface-reflected sidelobe is 10 dB down from the peak; 0.07 to 0.10 beamwidth for -20 dB sidelobes; 0.025 to 0.035 for -30 dB sidelobes; 0.008 to 0.011 for -40 dB sidelobes; and about 0.003 beamwidth for -50 dB sidelobes il- luminating the surface. Low-Angle Squinted-Beam Height Finding. 
 Furthermore, radar scattering from land is  affected by rain, snow cover, the type of vegetation or crops, the time of year, the presence of  streams and lakes, and man-made objects interspersed among the terrain. There can he  considerable variability in both land and sea clutter. This inherent variability must be under-  stood and properly accounted for in radar system design. 
 NotethatPCa=1/4aBistheprobability offalsealarmassuming thatindependent deci­ sionsastothepresence orabsenceofatargetaremadeBtimesasecond.Astheradarscansby atargetitreceives 11pulses.Ifthese 11pulsesareintegrated beforeatargetdecision ismade. thenthereareBinpo.ssible decisions persecond.Thefalse-alarm probability isthus11timesas great.Thisdoesnotmeanthattherewillbemorefalsealarms,sinceitistherateofdetection­ decisions thatisreducedratherthantheaveragetimebetween alarms.Thisisanother reason theaverage false-alarm time1(aisamoresignificant parameter thanthefalse-alarm probabi­ lity.Inthistext,Prawillbetakenasthereciprocal of1(aB=IIf'unlessstatedotherwise. Som~ authors 11prefertodefineafalse-al~rm numbernlthattakesaccount thenumberofpulses integrated, suchthatnj-=11fIn.Therefore, cautionshouldbeexercised whenusingdifTerent authors' computations forthesignal-to-noise ratioasafunction ofprobability ofdetection. 
 COMPUTING KIECHANISMS AND LINnGm-&oboda 28. INDEx—Henney. RADAR SYSTEM c1~s,\NsT,rF *P c+ EditedbyJIJLLu1947 LOUIS N.RIDENOUR%?Fl@PF(OFESSOFI OF PHYSICS UNIVERSITY OF PENNSYLVANIA Fllis’r’ E1)[TION . 
 The guard channel is processed similar to the Σ channel. The guard channel’s pur - pose is to blank sidelobe detections, as described in Section 4.2. Postprocessing. 
 B. White, “Multipath coordinate registration and track fusion for over- the-horizon radar,” in Defence Applications of Signal Processing,  D. A. 
 The active transistor area on the surface of the chip (the chip is sometimes called  the die) is typically divided into manageable units (cells), where the cell size is often  optimized for a particular application or range of applications. In addition to frequency  considerations, pulse width and duty cycle or, as a result, the peak and average dis - sipated power, are the parameters that determine the cell size and arrangement of  cells on a chip. The ultimate operating junction temperature of the transistor is largely  dependent on the transient heating that will be encountered and the layout and area of  the individual cells. 
 Intuitively, the mid-value /angbracketleftBcosθ/angbracketrightof Figure 3c should be located at around 5 TECU which corresponds to an altitude of about 400 km. Though we only take one group of data as an example, most cases satisfy this mode where the altitude for the mid-value /angbracketleftBcosθ/angbracketrightis a little higher than the peak height of the ionosphere as long as the TEC of the topside proﬁle is larger than the TEC of the bottom side. However, it was still not possible for us to determine a speciﬁc mid-value for each scene of PolSAR, so we experimented on three different altitudes to see how precisely the PolSAR could estimate TEC and how the magnetic ﬁeld inﬂuences the TEC value. 
 Sel. T op. Appl. 
 Nevertheless, it is important to know and understand how propagation phenomena  can influence radar performance since it can be a major factor in determining how well a radar  performs·in a particular application.  441 . 442 INTRODUCTION TO RADAR SYSTEMS  12.2 PROPAGATION OVER A PLANE EARTH  Although there are but few situations where accurate predictions of radar propagation effects  can be made by assuming a flat rather than round earth, it is nevertheless instructive to  examine this special case. 
 Since the pass and rejection bands of the two cancel - ers overlap, the MTI improvement factor for each clutter source is a function of their  spectral separation. Figure 3.29 shows the improvement factor for a double canceler, which consists of  two single cancelers, each tracking one of the spectra. It can be seen that as the separa - tion varies from 0 to 1/2 of the PRF, the performance degrades from that equivalent to  a double canceler to the performance of a single canceler at half of the PRF . 
 The proposed RCS curve denoising method can remove the noise from the RCS curve extracted from the real data. It makes the result of aspect entropy extraction more accurate. Since the aspect entropy of different types of targets falls into different ranges, targets can be discriminated from each other by the aspect entropy value. 
 8, pp. 43-47,  November, 1965.  276INTRODUCTION TORADAR SYSTEMS 83.vanderMaas,G.J.:ASimplified Calculation forDolph-Tschehyscheff Arrays,J.AprlPhrs.,vol.25. 
 PLES FROM EACH OF THE OTHER CHAPTERS IN THIS BOOK  BUT THIS LISTING IS SUFFICIENT TO INDICATE THE TYPE OF ADVANCES THAT HAVE BEEN IMPORTANT FOR IMPROVED RADAR CAPABILITIES £°Ê **  /" -Ê"Ê, , -ILITARY !PPLICATIONS  2ADAR WAS INVENTED IN THE S BECAUSE OF THE NEED  FOR DEFENSE AGAINST HEAVY MILITARY BOMBER AIRCRAFT 4HE MILITARY NEED FOR RADAR HAS PROBABLY BEEN ITS MOST IMPORTANT APPLICATION AND THE SOURCE OF MOST OF ITS MAJOR DEVELOPMENTS  INCLUDING THOSE FOR CIVILIAN PURPOSES 4HE CHIEF USE OF MILITARY RADAR HAS BEEN FOR AIR DEFENSE OPERATING FROM LAND  SEA   OR AIR )T HAS NOT BEEN PRACTICAL TO PERFORM SUCCESSFUL AIR DEFENSE WITHOUT RADAR )N AIR DEFENSE  RADAR IS USED FOR LONG 
 ING CROSS 
 Unlike Class-A linear amplifiers, there are peculiar operating characteristics of the Class-C-biased amplifier that must be recognized in the overall amplifier design. Among these are the RF characteristics of the device as a function of varying RF input drive levels, varying collector voltage supply levels, or varying load impedance. As the RF input drive level of a Class-C-biased device is in- creased from zero, the dc potential of the reverse-biased base-emitter junction is surpassed and the device begins to draw collector current from the fixed dc sup- ply voltage. 
 However, nine cascaded double-tuned circuits, each 6 Me/see wide, would combine togive a3.2-Me/see over-all bandwidth. The over-all bandwidth ofncascaded double-tuned circuits isgiven by over-all bandtidth =single stage bandwidth 1.1q; The usefulness ofdouble-tuned circuits inwideband amplifiers has been demonstrated bytheir incorporation inaradar receiver having 120 I a=#d!a2 0.2 “\IIII\I /’ I 0.1‘I I I I I I I I I I I I I I IFrequency (a)Singletuned (b)Doubletuned (c)Staggertuned FIG. 128.-Amplifier response cum es. 
 9.1to9.12byW.M.Cady. 271. 272 ANTENNAS, SCANNERS, A.VDSTABILIZA TIO.Y [SEC. 
 ASPECT 3EARCH CAN BE EITHER A SINGLE HIGH 
 BLANKER  A CLOSED 
 ,",  
 Part ofthe8-kv modulator pulse. 608 EXAMPLES OFRADAR SYSTEM DESIGN [SEC.1510 delivered tothe pulse transformer input iscapacitively coupled tothe keep-alive connection ofthe TR tube. The delay inthe pulse trans- former and magnetron issuch that this pulse arrives atthe TR tube slightly before ther-fpulse arrives. 
 The antenna illuminated a 100-km-swath width at the surface of the earth with an antenna elevation beamwidth of 6° that was oriented at an angle of 20° with respect to the nadir. Upon reception of the reflected signal by the receiver in the radar sensor, the return signal was amplified by a sensitivity- time-controlled RF amplifier. This signal and a fraction of the radar stalo were then combined and transmitted to a ground station by an analog data link. 
 cc ¯    WHERE S IS THE RELATIVE TIME DELAY AND  FD IS DOPPLER SHIFT 4HE RELATIVE TIME DELAY IS  POSITIVE FOR A TARGET FURTHER IN RANGE THAN A REFERENCE TARGET  AND DOPPLER FREQUENCY IS   POSITIVE FOR AN INCOMING TARGET NEGATIVE RANGE 
 65.Chandler, R.A.,andL.E.Wood:SystemConsiderations fortheDesignofRadarBraking Sensors, IEEETraIlS.,vol.VT-26,pp.151-160, May,1977. 66.Queen,F.D.:RadarCrossSections oftheT-38Aircraft fortheHead-On Aspects inL,S,andX Bands,Na!'alResearcll Lahoratory'Report 7951,Jan.8,1976. 67.Jao,J.K.,andM.Elbaum: First-Order Statistics ofaNon-Rayleigh FadingSignalandItsDetection, Proc.IEEE,vol.66,pp.781-789, July,1978. 
 ERATION AT EACH MEASUREMENT INTERVAL MODEL NO    THE GAINS INCREASE TO  @  A  ¼ ¼     WHICH IS THE LIMIT OF FILTER STABILITY 4HUS  THIS MODEL PRODUCES FILTER GAINS THAT  ARE THE MOST AGGRESSIVE AT MINIMIZING LAGS TO MANEUVERSAT THE EXPENSE OF LARGER      
 ZONE )N FACT  IT IS EVEN SEEN THAT FOR RANGES BETWEEN  AND  NAUTICAL MILES  THE CLUTTER 
 VA. 8.1.1.2 ASV Mk. X During 1943, concern was growing over the likely development by the Germans of a warning receiver for the 10 cm band. 
 6.AFC control circuits. 7.I-famplifier (usually uptol-volt video level). This setofcomponents, mounted asagroup and usually inaclosed container, iscalled the “R-f Head.” Alternative terms are“R-f Unit” and “Transmit-receive Unit. 
 Reo, vol 71,  pp. 425-433, Apr. 1, 1947. 
 Thedirective gainofatransmitting antenna maybedefined as G _maximum r~~~a~!~!1_i~~~~~ity D-average radiation intensity wheretheradiation intensity isthepowerperunitsolidangleradiated inthedirection (0,4» andisdenotedP(8,4».Aplotoftheradiation asafunction oftheangularcoordinates iscalled aradiation-intensity pattern.Thepowerdensity,orpowerperunitarea,plotted as'~function of angleiscalledapowerpattern. Thepowerpatternandtheradiation-intensity patlernare identical whenplottedonarelativehasis,thatis,whenthemaximum isnormalized toavalue ofunity.Whenplottedonarelativebasisbotharecalledthelltltemw radiation patkm. Anexample ofanantenna radiation patternforaparaboloid antenna isshownplottedin Fig.7.1.3Themainlobeisatzerodegrees. 
 Any use is subject to the Terms of Use as given at the website. Meteorological Radar.  METEOROLOGICAL RADAR  19.496x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 186. S. 
 Lab.  Rept. 6024, Cambridge, MA, 1946. 
 Spurious echoes may reach thereceiving crystal ineither oftwo principal ways. Ifthevibratory signal entersthebacking material itmay emerge later, unless care istaken toabsorb ordisperse the energy. Ontheother hand, iftheenergy ispredominantly reflected atthe surface ofboth end cells bytheuseofamismatching material incontact with thepiezoelectric quartz, thesignals may return tothereceiving end a second time after reflection, first from the receiving and then from the transmitting quartz.. 
 Once it has been established that RGPO is active,  several devices can be adopted in order to prevent the loss of the target under track.  1. A first approach consists of maintaining two tracks until the RGPO is deactivated. 
 ENCE REQUIREMENT OF  METERS AZIMUTH RESOLUTION )T FOLLOWED THAT SINGLE 
 Offutt, W. B.: A Review of Circular Polarization as a Means of Precipitation Clutter Suppression and  Examples, Proc. Natl. 
 TYPE TRACKERS THAT MOVE THE BEAM SLOWLY ENOUGH THAT A TARGET WILL REMAIN WELL WITHIN THE BEAM FOR THE SHORT EXAMINATION PERIOD OF THE RANGE INCREMENTS 4ARGET ACQUISITION INVOLVES CONSIDERATION OF THE  3. THRESHOLD AND INTEGRATION TIME  NEEDED TO ACCOMPLISH A GIVEN PROBABILITY OF DETECTION WITH A GIVEN FALSE 
 The larger the  ratio of the bandwidths M, the less the loss. For example, for a 0.5 probability of detection and  a probability of false alarm, the loss is 1.0 dB for M = 100, 2.2 dB for M = 20, and 7 dB  for M = In essence the Dicke fix (that uses wideband limiting) samples the adjacent  resolution cells in the frequencyldomain, as compared to the cell-averaging CFAR that  samples the background in the adjacent resolution cells in the time domain.  When the product of the bandwidth Band the pulse width z is greater than unity, as in a  pulse compression radar, the loss is determined by the product MBr rather than M. 
 12,10.—Video amplifier. referred toasthe“cutoff frequency. ” For theamplifier shown thi~ occurs when j=-!L23rRC’(11) where R=parallel resistance ofR=and R~,and Cisthetotal capacity to ground which includes output and input capacities plus stray capacities. 
 These devices generate the waveform by accu - mulating phase information, which is then used to look up values of the waveform (usually  a sine wave). This is converted to an analog signal with a digital-to-analog converter (DAC  or D/A converter) and filtered. A variety of waveform types (e.g., LFM, NLFM, and CW  waveforms) can be generated in this way by using the appropriate phase modulation char - acteristic. 
 6. J. R. 
 Integrating Equation (3) with respect to height gives 1 (NmF2)2/integraldisplay Ne2dh=/integraldisplay e1−z−e−zdh. (4) According to [ 22–24], if the electron density proﬁle is Chapman-model based, we have /integraldisplay Ne2dh=0.66 Nemax TEC , (5) where Nemaxis the maximal electron density along the path. Referring to the topside proﬁle only, we can obtain from Equation (5)/integraldisplayHS hmF2Ne2dh=0.66 Nemax TEC To p. 
 Common Pulse Characteristics   Pulsed radar t ypically utilizes very low duty cycle RF pulses ( <  10%) . The r ange and resolution is determined b y the pulse  repetition frequency ( PRF), pulse width  (PW) , and transmit  power . A wide PW generally provide s better  range, but poor  resolution . 
 Atlas, D., and R. K. Moore: The Measurement of Precipitation with Synthetic Aper- ture Radar, J. 
 An interesting technique for graphically portraying the variation of the beam shape with  scan angle has been described by Von Aulo~k,'~ an example of which is shown in Fig. 8.3. The  antenna radiation pattern is plotted in spherical coordinates as a function of the two direction  cosines, cos a, and cos a,, of the radius vector specifying the point of observation. 
 15.5  15.2 Clutter Filter Response to  Moving Targ ets  .............  15.7  15.3 Clutter Characteristics  ............................................  15.8  Spectral Characteristics  ..................................... 
 This item is the same for the two antennas. According to Formula (26), it is found that phase information of the scattering point in target ISAR image contains height information of the scattering point, interferometric processing for two ISAR images is conducted, and the interferometric phase difference of Pimages is: Δϕ=4πf c(Rcosα2+( R0tanα2−z)sinα2−(Rcosα1+( R0tanα1−z)sinα1)) =4πf c(R(cosα2−cosα1)+ R0(tanα2sinα2−tanα1sinα1)−z(sinα2−sinα1))(28) In the InISAR imaging system, the baseline length is much less than the distance between the antennas and target, so pitch angle difference between the antenna TR1and TR2is very small, namely α2=α1+Δα,Δα/lessmuch1. In this paper, the antenna TR2is at the origin, so α1=0,α2=Δα, and the height of the scattering point can be estimated as: z=λ 4πΔϕ−Rcosα2−R0tanα2sinα2 −sinα2(29) When the antenna TR1and TR2are symmetrically distributed in the coordinate origin, namely α1=α2, the height of the scattering point is estimated as: z=Δϕλ 8πsinα1(30) For target containing Kscattering points, the height of each scattering point can be estimated by interferometric processing of the corresponding pixel points in the two ISAR images. 
 Four antennas were used to measure wind speed in the range from 4 to 28 m/s. The microwave radiometer had five frequency channels at 6.6 GHz, 10.6 GHz, 18 GHz, 21 GHz, and 37.6 GHz. A swath 1000 km wide, centered at the nadir, was covered. 
 REFERENCES  1. A. V . 
 and M. Marchant: Structural Aspects: pt L Elementary Design Considerations.  chap. 
 Livingstone, B. Brisco, R. J. 
 Low-frequency approximations developed for the Rayleigh region  can extend upward into the resonance region. Exact Methods.  The exact methods are based on either the integral or differen - tial form of Maxwell’s equations. 
 However, the sidelobes ,,I of the Barker codes can be further lowered by employing a mismatched filter and accepting a  slight loss in the peak signal-to-noise ratio.31  Comparison of linear FM and phase-coded puke compression. Both of these waveforms have  their areas of application; but in the past, the linear FM, or chirp, pulse compression has  probably been more widely used. The time sidelobes of the phase-coded pulse are of the order  of l/BT. 
 Theotheristhepoweramplifier, whichutilizesalowpower, stableoscillator whoseoutputisraisedtotherequired powerlevelbyoneormoreamplifie; stages.The ~Iystron, traveling-wave tube,andthecrossed-field amplifier areexamples of microwave power-amplifier tubes.Thechoicebetween thepoweroscillator andthepower amplifier isgoverned mainlybytheparticular radarapplication. Transmitters thatemploythe magnetron power-oscillator areusuallysmallerinphysical sizethantransmitters thatemploy thepoweramplifier. Thevariousamplifier transmitters, however, aregenerally capableof higherpowerthanthemagnetron oscillator. 
 Moving the guide tilts thebeam. Aconducting reflector strip isplaced between theplates insuch away that thewaveguide feeds the lens from anadjacent edge ofthe plates (Fig. 9.34b). 
 99, pp. 21803–21824, 1994. 73. 
 The reference signal to the second phase detector is generated with a 90° phase relation to the original reference. This provides a similar error voltage proportional to the azimuth-angle error and with polarity corresponding to the di- rection of error. A secant correction (Fig. 
 CALLY INDEPENDENT TRIALS ARE PERFORMED TO ACHIEVE A SIGNIFICANT SAMPLE OF THE OUTPUT VALUES FROM WHICH RELIABLE STATISTICS CAN BE ESTIMATED .   %,%#42/.)# #/5.4%2 
 Separate antennas are ihdwn-for*trans&&ion and reception. instead of the usual local oxilla-  tor found in the conventiona~~susupirhet'e~6d~ne I '. receiver, the local oscillator (or reference  signal) is derived in thii receiver from a portion of the transmitted signal mixed with a locally  generated signal of frequency equal to that of the receiver IF. 
 BEAM JAMMING OF A NARROW BEAM RADAR TENDS TO PROVIDE A STROBE IN THE DIRECTION OF THE JAMMER  WHICH CAN BE USED TO TRIANGULATE AND REVEAL THE JAMMER LOCATION 7IDER RADAR BANDWIDTH  WITH APPROPRIATE CODING  FORCES THE JAMMER TO SPREAD ITS ENERGY OVER A WIDER BAND  THEREBY DILUTING THE EFFECTIVE JAMMING ENERGY  %##- DESIGN PRINCIPLES FOR MAIN 
 RATION FOR VARIOUS SPACE 
 andtheconstant flexingofthematerial inthewind.Inhigh windsthematerial canhedamaged byflyingdebrisandtherotation oftheantenna mighthave toceasetopreventthefabricfrombeingblownagainsttheantenna andtorn.Maintenance of theinternal pressure inhighwindscansometimes bedifficult. Another problem isthatcostly maintenance isrequired atfrequellt intervals. Thelimitations ofair-supported radomes areovercome bytheuseofrigidself-supporting radomes. 
 13. Ilycr n~itl (i. W. 
 344 INTRODUCTION TO RADAR SYSTEMS  reference signals are needed to properly extract target information. Specific applicat~orls such  as MTI radar, tracking radar, or radars designed lo ~nill~lni~c clutter placc special tler~la~~ils 011  the receiver. Receivers that must operate with a transmitter whose frequency can drift need  some means of automatic frequency control (AFC). 
 The scale on the range marker control Figure 3.7. H2S Mk. IIB radar operator ’s position, showing indicator unit type 162, switch unit type 207 and a top of picture, part of the ﬁshpond display [Crown copyright 1944, released under OGL v3.0; 1944/3302, 09 Jul 1944, RCM in Fortress, MRATHS].Airborne Maritime Surveillance Radar, Volume 1 3-10. 
 SCALE IONOSPHERIC STRUCTURE AS DEFINING THE PROPAGATION GEOMETRY THROUGHOUT THE ILLUMINATION VOLUME  WHEREAS THE DYNAMICAL PROCESSES IMPOSE THEIR RESPECTIVE MODULATIONS ON THE TRANSIT 
 1, pp. 219-230, 1958.  69. 
 DENCE AT  -C   -C  AND EXTENSION OF ANALYSIS TO 8 BAND v 5NIVERSITY OF .EW -EXICO   %NG %XP 3TA  42 %% 
 (The angle of the target/image bisector is approximately given by the ratio of the radar  antenna-height-to-target-range.) . 176 INTRODUCTION TO RADAR SYSTEMS  The normal monopulse radar receiver uses only the in-pbase (or the out-of-phase) com­ ponent of the difference signal. When there is a multipath signal present along with the direct  signal, a quadrature component of the difference signal exists. 
 and {I. as defined in Eq. ( l l.16), as well as between the expressions for of and oTR. 
 The latter effect was  not exploited initially, but was later used for airborne mapping radars.  Until the middle of 1940 tlie development of radar in Britain and the United States was  carried out independently of one another. In September of that year a British technical mission  visited the United States to exchange information concerning the radar developments in the  two countries. 
 TION AND MINIMUM LOSS AT THE DESIGN RANGE &OR SOME PULSE COMPRESSION WAVEFORMS   THE ECLIPSING LOSS IS ALMOST LINEAR AND PARTIAL OVERLAP STILL ALLOWS SHORTER 
 155.  22. Ilavics. 
 At the lower HF  frequencies where the wavelength is large compared to the target dimensions, the cross section  will be in the Rayleigh region where r~ decreases rapidly with decreasing frequency. If the  frequency is sufficiently low, the cross section of small aircraft or missiles might be smaller  than their microwave values.  It was mentioned that external sources of interference from other HF users can limit the  sensitivity of the HF radar receiver. 
 300.  March. 1967. 
      
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 24.62  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 77. 
 RANGE RESOLUTION OBTAINED BY THIS METHOD IS NOT AS GOOD AS THE RANGE RESOLUTION 6ERY GOOD RESOLUTION IN THE CROSS 
 The digital outputs of the I and Q channels are  combined by taking the square root of IZ + Q~. An alternative method of combining, which is  adequate for most cases, is to take 11 I + I Q I. The combined output is then converted to an  analog signal by the digital-to-analog (D/A) converter. 
 Since the targets are under track, their approximate  ranges are known so that a beam need be formed in the proper direction only during the time  that a target echo is expected. In this manner, several targets can be held in track during the  interpulse period, provided the phase shifters can switch sufficiently rapidly and a control  computer is available to take advantage of the inherent flexibility of the array.  8.8 RANDOM ERRORS IN ARRAYS  In the analysis of the effects of reflector-antenna errors in Sec. 
 TION OF A DOPPLER FILTER BANK CAN BE REPLACED BY A &)2 IMPLEMENTATION  MORE DESIRABLE &)2 FILTER RESPONSES CAN BE REALIZED THROUGH THE USE OF APPROPRIATE NUMERICAL DIGITAL FILTER DESIGN TECHNIQUES 4HE GOAL IS SIMILAR TO THAT PURSUED WITH THE EMPIRICAL FILTER DESIGNS DISCUSSED EARLIER BUT FILTERS WITH A LARGE NUMBER OF TAPS CAN BE DESIGNED TO EXACTING SPECIFICATIONS !S AN EXAMPLE  CONSIDER THE DESIGN OF A DOPPLER FILTER BANK FOR AN 3 BAND  '(Z   RADAR USING A #0) OF  .    PULSES USING A 02& OF  K(Z !SSUME THAT THE RADAR REQUIRE 
 Figure 3.17 shows the sum and difference main-beam patterns for an aperture  20 wavelengths long. Figure 3.18 shows the residue for the case when the fraction  of the horizontal aperture width a traveled per interpulse period Tp, Vn = VxTp/a, is  equal to 0.04 and when the number of wavelengths that the aperture tip rotates per  interpulse period, Wn = awrTp/2l, is equal to 0.04. The corresponding improvement  factor is 52 dB. 
 379-389, August, 1975.  12. Trunk, G. 
 FACED RADAR USES  ACTIVE 42 MODULES PER FACE  AND EACH MODULE INTERFACES WITH A DIPOLE ANTENNA ELEMENT %XTRA ELEMENTS AND A NARROW BEAM ARE USED ON RECEIVE  AND UPGRADE CAPABILITY HAS BEEN INCLUDED FOR THE FUTURE INSTALLATION OF UP TO  42 MODULES PER  ARRAY FACE 4HE PEAK POWER OUTPUT FROM EACH FACE  WHEN POPULATED WITH  MODULES IS  K7  AND THE AVERAGE POWER OUTPUT IS  K7 !MONG THE  MODULES PER FACE  GROUPS OF  42 MODULES ARE OPERATED AS A  SUBARRAY )N TRANSMIT  A HIGH 
 1  2 Electromagnetic field theory &  wave propagation basics ................................................... 7  2.1 Fields and Waves in Free Space ........................................................................................ 8  2.2 Reflection on Perfect Conducting Bodies ......................................................................... 
 However, they were (and still are) difficult and expensive to develop, often requiring  several design iterations before the device was fully operational. If an ASIC-based  system needs to be modified, the ASICs need to be redesigned, incurring significant  expense. Typically, the use of ASICs makes sense if tens or hundreds of thousands of  units are to be sold, so that the development costs can be amortized over the life of the  unit. 
 Radomes cause four major electrical effects on antenna performance. Beam deflec - tion is the shift of the electrical axis, which is critical for tracking radar. Transmission   loss is the measure of energy lost by reflection and absorption. 
 28 of" Radar Handbook," M. I. Skolnik (rd.),  McGraw-Hill Book Co., New York, 1970. 
 This redefinition is desirable because when radar system designers or manufacturers specify a transmitter power, the actual transmitter output power is usually meant. With this changed definition, Pt must be replaced by /VL,, where Lt is a loss factor defined as the ratio of the transmitter output power to the power actually delivered to the antenna. (Therefore, Lt ^ 1.) It will later prove convenient to introduce additional loss factors similarly re- lated to other factors in the range equation. 
 Thetwo-element arrayisatrivialexample oftheButlerbeam-forming antenna. Figure H.2Hillustrates thccircuitofancight-clcmcnt arraythatgcneratcs eiglltindcpendent beams.It utilizes12directional couplers andeightfixedphaseshifters.TheButlermatrixhas2"inputs and2"outputs. Modifications oftheButlerarraytoanynumber ofelements havebeen suggested, buttheresulting beam-forming network isnotnecessarily lossless. 
 There is some cross-polarized response for  the linear signal and some unpolarized signal. For the urban area shown, the strongest  responses are tilted in orientation in both the copolarized and cross-polarized cases.  FIGURE   16. 
 This is theorigin ofthe commonly specified upper limit formismatch. There isafurther limitation ifthe mismatch occurs atthe end ofa long line-for example 50to100wavelengths from themagnetron. Then asthefrequency changes thenumber ofwavelengths intheline changes, and soalso does the phase ofthe standing wave. 
 The towers would have tomove only one inch relative toeach other tochange from constructive todestructive interference. InEq. (23) wenote further that thereturn power from acomplex target consisting oftwo equal isotropic scatterers afixed distance apart depends upon k,and that the change insignal foragiven wavelength change increases with the value of1.This fact has been applied ina 18ee Propagation ofShort Radio ~~aves, Vol. 
 Whenmorethanonetargetispresentwithintheviewoftheradar,themixeroutputwill contain morethanonedifference frequency. Ifthesystemislinear,therewillbeafrequency component corresponding t9eachtarget.Inprinciple, therangetoeachtargetmaybe determined bymeasuring theindividual frequency components andapplying Eq.(3.11)to each.Tomeasure theindividual frequencies, theymustbeseparated fromoneanother. This mightbeaccomplished withabankofnarrowband filters,oralternatively, asinglefrequency corresponding toasingletargetmaybesingled outandcontinuously observed withanarrow­ bandtUllablefilter.Butifthemotionofthetargetswcretoproduce adoppler frequcncy shift, orifthefrequency-modulation waveform werenonlinear, orifthemixerwerenotoperated in itslinearregion,theproblem ofresolving targetsandmeasuring therangeofeachbecomes morecomplicated. 
 CRAFT IN ORBIT AT ALTITUDE H ABOVE A PLANET OF RADIUS 2 0 AND MASS -0 IS GIVEN BY   6- ' 2 H003#           .ADIR IS THE POINT BELOW THE SPACECRAFT ON THE SURFACE INTERSECTED BY THE RADIUS VECTOR FROM THE %ARTHS CENTER TO  THE SPACECRAFT o  )NCLINATIONS GREATER THAN  n ARE RETROGRADE BECAUSE THEIR % 
 2.68  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 delay of the clutter return, R is the clutter range , and c is the speed of light. For the  second adjustment due to the frequency response of the clutter filters, which as stated  previously are assumed to be FIR cancelers with binomial weights, it is noted that  the response at very low frequencies fall off at 20 dB per decade for one delay, 40 dB  per decade for two delays, 60 dB per decade for three delays, etc. As an example,  the approximation used for a two-delay MTI filter is shown in Figure 2.75. 
 Hatcher, J. L., and C. Cash: Polarization Agility for Radar Glint Reduction, IEEE Region 3 Co111·e11- tion, Huntsville, Alabama, Nov. 
 Most parabolic-reflector antennas seem to have  f/D ratios ranging from 0.3 to 0.5.  Reflector surfaces. Tlie reflecting surface may be made of a solid sheet material, but it is often  preferable to use a wire screen, metal grating, perforated metal, or expanded metal mesh. 
 E. McKee; Wind Forces on Parabolic Antennas, Microwave J., vol. 8, pp. 
 Shrader, W.W.: MTI Radar, chap. 17 of" Radar Handbook." M. I. 
 [ CrossRef ] 4. Arcioni, M.; Bensi, P .; Davidson, M.W.; Drinkwater, M.; Fois, F.; Lin, C.C.; Meynart, R.; Scipal, K.; Silvestrin, P . ESA’S BIOMASS mission candidate system and payload overview. 
 Turner (eds.): "Radar Scanners and Radomes," MIT Radia-  tion Laboratory Series, vol. 26, p. 66, McGraw-Hill Book Company, New York, 1948. 
 This suggest that the wind speed has more inﬂuence on the brightness contrast of the overall SAR image than on the visibility of the eddy spirals. On the other hand, the results indicate that the values of ΔσandΔσrare larger at higher radar frequencies, which is the same as the conclusion drawn from Figures 13and 15. Referring to existing theories, a possible explanation for this conclusion should be the less defocusing effect as the radar frequency gets higher. 
 16.5 SCANNING-MOTION COMPENSATION Figure 16.14a shows a typical antenna main-beam radiation pattern and the re- sponse of a point scatterer for two successive pulses when the antenna is scan- ning. It is seen that the signals returned would differ by AG2(6). This results in imperfect cancellation due to scanning. 
 The majority ofexisting magnetrons areofthis type. A variety ofother designs have been constructed, most ofwhich have not proved tobeassatisfactory asthe strapped type. One type, however, has several marked advantages over strapped tubes. 
 FIRMED BY ADDITIONAL DWELLS 0HASE CONTROL ALLOWS BEAMS TO BE WIDENED  FOR EXAMPLE  TO REDUCE SEARCH TIME FOR THE MORE ELEVATED REGIONS  WHERE REDUCED RANGES NEED LESS ANTENNA GAIN ! SEPARATE ROTATING SURVEILLANCE RADAR SYSTEM MAY BE ADDED FOR EXTRA COVERAGE AT A SECOND FREQUENCY  AND TO ALLOW THE $ RADAR MORE TIME FOR TRACKING -ONOPULSE 4RACK  0HASED ARRAY RADARS ARE WELL SUITED FOR MONOPULSE TRACKING  4HE RADIATING ELEMENTS OF THE ARRAY CAN BE COMBINED IN THREE DIFFERENT WAYS TO GIVE THE SUM PATTERN AND THE AZIMUTH AND ELEVATION DIFFERENCE PATTERNS  #ONTRADICTORY REQUIRE 
 TIME INTERRUPTS !  SECOND CLASS CONTAINS 2& AND INTERMEDIATE FREQUENCY )&  AMPLIFICATION AND MIXING ! THIRD CLASS CONTAINS LOW NOISE FREQUENCY SYNTHESIZERS  WHICH MAY INCLUDE $IRECT $IGITAL 
 A bandwidth factor may, therefore, be defined in terms of the  broadside beamwidth:  Bandwidthfactorbandwidth(%) beam width (= =°K) )  A reasonable criterion is to limit the bandwidth so that the beam never scans by  more than ± one-fourth of a local beamwidth frequency, i.e.,  Criterion:(scanned)∆q q0 1 4B≤  With a scan of 60 °, this gives K = 1, and in terms of broadside beamwidth the limit is  Bandwidth (%) = beamwidth ( °) (CW)  For example, if the array has a beamwidth of 2 ° this criterion permits a 2% change  in frequency prior to resetting the phase shifters. This allows the beam to move from  one-fourth beamwidth on one side of the desired direction to one-fourth beamwidth  on the other side as the frequency changes by 2%. At smaller scan angles, the effect is  reduced as given by Eq. 
 DATA 
 VAPOR ABSORPTION LINE AT  '(Z  WHICH CAUSES  ATTENUATION THAT CAN BE A SERIOUS PROBLEM IN SOME APPLICATIONS 4HIS WAS DISCOVERED AFTER THE DEVELOPMENT OF + 
 Aperture blocking can he min­ imized by designing the parabolic portion of the torus as an offset parabola.just as in the cast.:  of a paraboloid.  Other feed-motion scanners. There exist a number of antennas in which the beam is rapidly  scanned over a limited sector by the mechanical motion of the feed. 
 TRACK ASSOCIATIONS UP TO AN UNAC 
 x 19.125 high = 25,559  cubic inches (including feed)  Signal processor 20 long x 13.5 wide x 10 high = 2700  cubic inches  177 . MacArthur, Marth, Wall -The GEOSA T Radar AlliJlleler  Figure 2-The GEOSAT RF deck/signal processor .  Figure 3-The GEOSAT radar altimeter antenna. 
 Exanlplcs of the common types of scantling patterns employed with pencil-beam antennas are  illustrated in Fig. 5.18.  In the helical scan, the antenna is cor~tinuously rotated in azimuth while it is simulta-  neously raised or lowered in elevation. 
 12.2, which gives the elevation angle of the lowest interference  lobe as )./41,a, where A = wavelength and Ira = antenna height Thus if targets low on the water  are to be seen, higher frequencies may be preferred even if the clutter is greater. Another  reason for preferring the higher frequencies in some applications, in spite of the larger clutter,  is that greater range-resolution and azimuth-resolution (shorter pulse width and narrower  beam widths) are easier to obtain than at lower frequencies. The higher resolution usually  results in greater target-to-clutter ratio. 
 An anti-TR rhumbatron, CV179, was ﬁtted at the quarter wavelength position in a half wavelength tuning stub in the feed from the trans-mitter. On transmit, both rhumbatrons ﬁred, feeding the transmitter pulse to the antenna. On reception, both reverted to their low impedance state for the desired signals and the anti-TR rhumbatron tuning stub re ﬂected an open circuit towards the magnetron, preventing losses to the received signals. 
 = ~~{!__'1. min ,,r (14.39)  where "r = required number of signal photoelectrons, 11 = quantum efficiency of the detector,  and r = observation time. With these substitutions, and with 2B = 1/r (assuming a video  receiver) the radar equation can be written  ( 14.40) . 
 97. E. A. 
 January, 196X.  30. Ridenour. 
 In one popular design the quartz was cut as  a 15-sided polygon in which the acoustic signal made 31 internal passes to achieve a total  delay time of 1 ms.  Electrostatic storage tubes have also been used for MTI delay lines. 34·40 The signals are  stored in the form of electrostatic charges on a mosaic or mesh similar to that of a TV camera  tube. 
 SPEED ANALOGUE 
 -  0RINCIPAL $IFFERENCES "ETWEEN (& AND -ICROWAVE 2ADAR  "EFORE ANALYZING  (& SKYWAVE RADAR SYSTEMS IN DETAIL IN THE SECTIONS THAT FOLLOW AND DESCRIBING THOSE  PROPERTIES OF THE ENVIRONMENT THAT IMPACT THEIR DESIGN AND PERFORMANCE  IT IS INSTRUC 
 ANISMS SUCH AS MULTIPATH INTERFERENCE  DIFFRACTION  TROPOSCATTER  AND TERRAIN MAY BE  INCLUDED !MONG THE GENERAL CLASS OF EFFECTIVE 
 If the trans-  mitted waveform is to have good clutter-rejection properties the ambiguity function should  have little or no response in the regions of clutter.  The problem of synthesizing optimum waveforms based on a desired amb&uity diagram  specified by operational requirements is a difficult one. The approach to selecting a waveform  with a suitable ambiguity diagram is generally by trial and error rather than by synthesis. 
 The block diagram of the SAR-SS proposed in this paper is shown in Figure 9. According to Figure 9, the single look complex (SLC) image is given as an input and the outer loop runs for each image range line. After the up-sampling process, a projection of the azimuth beam is used to limit the illumination time of each target in the scene (shown as the SAR image pixels). 
 Craig. S. W. 
 Manufacturing a product based on what the buyer thinks he or she wants may be a good  marketing strategy for many products, but in something like a radar, it might be better  for a customer to clearly specify what performance is wanted and then leave the decision  as to what RF power source should be used to the radar system designer. It is usually  better if the radar design can be determined by the radar system designer and not by the  manufacturer’s marketing department. The goals of the radar designer and the market - ing department are not always the same. 
 Siegel:" Methods of Radar Cross-Section Analysis." Academic Press,  Inc., New York, 1968, chap. 7.  101. 
 The improvement factor shown is  the improvement factor for a point scatterer averaged over the null-to-null antenna  beamwidth. In one case, the gain ratio k is optimized at each value of pulse-to-pulse  displacement. In the other compensated case, the optimum gain ratio k is approximated  by the linear function of interpulse platform motion kVx. 
 TRACKING RADAR  9.376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 above and below the average doppler of the target. A target typically has a significant  random yaw, pitch, and roll motion even on a “fixed” heading. Time plots of typical  aircraft heading for an aircraft flying a “straight course” are observed to have typical  random yaw motion that causes small changes in the doppler from each of the scattering  surfaces of the aircraft’s rigid structure. 
 2 2T    = 
 IEEE, vol. 62, pp. 687-704, June, 1974. 
 For a practical design, two empirical techniques are of great value: 1. Waveguide simulators provide a means for determining the element impedance  in an infinite array with the use of only a few elements. The effectiveness of a  matching structure based on these measurements may also be determined in the  simulator. 
 The instrument mass is 270 kg; input power required is 251 W. Thanks to onboard  processing, the inherent data rate is reduced from 1.4 Mbit/s to an average of 60 kbit/s  to the MetOp-1 payload data-handling system. NSCAT , the NASA Scatterometer,134 provided to Japan as part of the Advanced Earth  Observing Satellite (ADEOS) payload, was an upgraded version of SASS. 
 Many long-range ground-based  search radars use a ran-beam pattern narrow in azimuth and broad in elevation.  The rate at which a fan-beam antenna may be scanned is a compromise between the rate  at which target-position information is desired (data rate) and the ability to detect weak  targets (probability or detection). Unfortunately, the two are at cdds with one another. 
 The  conversion loss of typical microwave crystals in a conventional single-ended mixer  configuration varies from about 5 to 6.5 dB. A crystal mixer is called "broadband" when the  signal and image frequencies are both terminated in matched loads. A signal impressed in  the RF signal channel of a broadband mixer is converted in equal portions to the IF signal and  the RF image. 
 In general, the dynamic range of the sampling receiver is typically  60 dB, without range (time) varying gain. The effect of the range varying gain is to  enable the lower amplitude signals from targets at a greater range to be amplified so as  to be above the minimum sampling threshold signal level. This is equivalent to a linear  receiver with a 90 dB or more dynamic range. 
 WAY ANTENNA BEAMWIDTH  Q   REFLECTION COEFFICIENT AND 'SE PEAK  IS THE POWER RATIO OF THE TRACKING 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.856x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 Each map cell is updated by the radar returns (or residues) falling within its borders  (or in its vicinity) on several previous scans. 
 J. Harris: Submillimeter Waves, Tlie Radio and Electronic Engineer, vol. 46,  pp. 
 Two dispersive delay lines are used  with a hard limiter between them to provide CF AR. Both lines are of similar characteristics,  and the total pulse-compression ratio is divided between the two. In one design,41 the first  delay line compressed a 5 JLS pulse to 1.6 µs, and the second delay line following the limiter  compressed the L6 JlS pulse to 0.05 ,,s, for a total pulse-compression ratio of 100. 
 This can be done  by actually constructing a large number of matched filters, as in retrospective pro - cessing71 (see Figure 7.36), or by using a forward-tracking process with multiple  hypothesis formed and propagated. Just as automatic radar detection is a tradeoff between probability of detection  and probability of false alarm, new track formation is a tradeoff between the speed at  which a track is formed and the probability of erroneously forming a false track that  does not represent a physical object of interest. There are two types of false tracks:  (1) Tracks on real objects that are simply not of interest. 
  
 A high- resolution radar that obtains the profile of a target in both range and . cross range (as do SAR and ISAR) provides the size and shape of the target. The shape of an object can also be obtained by tomography, in which a two- dimensional image of a three-dimensional object is reconstructed from the measurement of phase and amplitude, at different angles of observation. 
 507, Oct. 10, 1975.  67. 
 LIMITED ALTIMETER !DAPTIVE 4RACKING  ! SATELLITE 
 Elec- trons arrive atthe anode atsuch atime astoconstitute aconduction current approximately 90° out ofphase with the r-fvoltage, and thus have little effect onthe oscillations. 10.4. Performance Charts and Rieke Diagrams.-Four parameters determine the operation ofthe magnetron; two areassociated with the input circuit, and two with the output circuit. 
 271 9.1 The Antenna Equation. 271 9,2 Round and Cut Paraboloid Antennas 272 93FanBeams ........ .274 94 Nonscanning Antennas. 
 Clearly in Figure 3a,Bcosθdecreases nearly linearly with the increase of altitude. TEC as a function of altitude could be obtained by integrating the electron density proﬁle of the ionosonde in Figure 3b. Taking advantage of the same variable, i.e., the altitude in the above two functions, we can plot Bcosθas a function of TEC, as shown in Figure 3c. 
 They are also used with d-c operated crossed-field amplifiers and modranode pulsed  linear-beam tubes which are connected,directly across a capacitor bank. The line-type modu-  lator does not usually require a crowbar since it stores less energy than the hard-tube modula-  tor and it is designed to discharge safely all the stored energy each time it is triggered.  6.9 SOLID-STATE TRANSMITTERS '  There have been two general classes of solid-state devices considered as potential sourczs of  microwave power for radar applications. 
 Introduction to the new metasensing ground-based SAR: Technical description and data analysis. In Proceedings of the 2012 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Munich, Germany, 22–27 July 2012; pp. 4790–4792. 
 48 Median values of s 0F4 at low depression angles (based on   Table 3.6 of Billingsley17)0.1 1 10 FrequencyMedian σ0F4 (dB)0 −10 −20 −30 −40 −50 −60 −70 Urban Mountains Desert & Grass ≥1° Desert & Grass ≤0.3°URBAN, MOUNTAINS, GRASS & DESERT VHF UHF L S X 0.1 1 10 FrequencyMedian σ0F4 (dB)0 −10 −20 −30 −40 −50 −60 −70FOREST VHF UHF L S X High Relief >1 ° High Relief ≤0.2° Low Relief 0.4 °–2° Low Relief ≤0.3°Low Relief >1 ° 0.1 1 10 FrequencyMedian σ0F4 (dB)0 −10 −20 −30 −40 −50 −60 −70AGRICULTURAL LAND VHF UHF L S X Slope >2 ° Slope 1°–2° Slope <1 °(a) (b) (c) ch16.indd   54 12/19/07   4:56:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 ON 
 Often, the azimuth and elevation beamwidth requirements differ, requir - ing an oblong aperture, as shown in Figure 12.17 b-e. If low sidelobe levels are required, feed blockage may become intolerable, requir - ing the use of an offset feed (Figure 12.17 c). The feed is still generally located at the  focal point, but the reflector is realized via use of a different portion of the parabola. 
 Practical three-dimensional problems often involve truncated segments of two-dimensional structures, such as shown in Fig. 11.1. In the practical world, those segments may be viewed at angles other than incidence perpendicular to the cylindrical axis, as implied in the solution of two-dimensional problems. 
 WAVE FREQUENCIES IN &IGURE  4HE IMPLICATION OF THIS GRAPH IS THAT FULL 42 MODULE FUNCTIONALITY MUST BE PACKAGED INTO THE SPACE AND VOLUME BEHIND THE PLANAR ARRAY  AND THIS REQUIREMENT CAN POSE VERY DIFFICULT CHALLENGES TO THE 42 MODULE   &)'52%   -AXIMUM OPERATING FREQUENCY AND WORST 
 chains, especially below 5 kHz, can be seen by comparing curve B (1970) with curve C (1988). Even better performance is to be expected as research in this very important area continues. Although the curves are given to 150 kHz at most, one is often interested in FM noise out to I/T (where T is the pulse length). 
 Although it has some advantages not found in other tubes, it has lower  gain than linear-beam amplifiers (so multiple stages of amplification are required),  and its noise level is higher than the linear-beam tube, which makes it less capable  for detecting moving targets in clutter. The gyrotron , which can be either an oscillator or an amplifier, is an RF * power  source that can produce very high power at millimeter wavelengths. Conventional  microwave power sources utilize resonant structures in which the phase velocity of the  electromagnetic field propagating along the RF structure is slowed so as to be close to  the electron beam velocity. 
 NOISE RATIO  0AV   AVERAGE TRANSMITTED POWER  'T   TRANSMITTER ANTENNA GAIN  'R   RECEIVER ANTENNA GAIN  4     COHERENT PROCESSING TIME  K   WAVELENGTH  R   TARGET RADAR CROSS SECTION  &P   PROPAGATION 
 Li, Y.; Yin, Q.; Lin, Y.; Hong, W. Anisotropy Scattering Detection from Multiaspect Signatures of Circular Polarimetric SAR. IEEE Geosci. 
 42. B. R. 
  
 As the aspect changes, this ﬂat surface will tend to reﬂect more ofthe energy of the beam away from the antenna, and may give rather weakechoes. A concave surface will tend to focus the radar beam back to theantenna while a convex surface will tend to scatter the energy. A smoothconical surface will not reﬂect energy back to the antenna. 
 END SERVERS AND EMBEDDED PROCESSOR ARCHITECTURES 3ERVERS ARE TYPICALLY HOMOGENEOUS PROCESSORS  WHERE ALL OF THE PROCESSING NODES ARE IDENTICAL AND ARE CONNECTED BY A VERY HIGH 
 Figure 23.7 is a plot of bistatic isodops in a two-dimensional bistatic plane, i.e.,  where the transmitter and receiver are at zero or near-zero altitude, for the following  conditions: VT = VR = 250 m/s, d T = 0°, d R = 45°, and  l = 0.03 m. Dimension of the grid on the bistatic plane is arbitrary; that is, the isodops are invari - ant with scale. On the left and right sides of Figure 23.7, the isodops are approximately  stationary, which are pseudo-monostatic operating points. 
 TURE RADAR SYSTEMS   )2% 4RANSACTIONS ON -ILITARY %LECTRONICS   VOL -), 
 RESOLUTION  
 BOARD COMPUTERS BLADES  THAT CONTAIN MULTIPLE GENERAL 
 24.17 Radar performance-controlling variables are given as a func- tion of range; January, 1800 UTC, SSN 50. Figure 24.18 shows the performance indicated with these assumptions for all ranges. A path factor enhancement of 6 dB has been chosen as an estimate of con- structive multipath interference for an aircraft target that is effective in target detec- tion. 
 Other radiators that have been used in phased arrays include microstrip antennas, 160  polyrods, helices, spirals, and log-periodic elements. Radiating elements are generally of low  gain, as is consistent with the broad-beamwidth needed for wide-angle scan and the narrow  sracing to avoid grating lobes. More directive elements can he used when the scanning of the  beam need not be over a wide angle. 
 11 to 16.12 Burst mode, in SBR SAR, 18.23 to 18.24 C C band, 1.16 Calibrate and self-test, 5.42 Cal ibration of meteorological radar, 19.18 to 19.19 Cascaded Integrator-Comb (CIC) Filters, 25.29 to 25.32 Cassegrain antenna, 12.21 to 12.23, 12.25, 14.34 Cassini, 18.46 Cathode pulser, 10.23 Cell-averaging CFAR, 7.11 to 7.12, 7.17 CFAR, 7.11 to 7.18 and ECCM, 24.35 to 24.36 loss, 4.44 probability of detection, 7.15 target suppression in, 7.16 to 7.17 Chaff, 24.5 to 24.6 Chaff and ECCM, 24.19, 24.34 Chart radars, 22.22 to 22.23 Chebyshev filter bank, 2.54 to 2.55 Civil Marine Radar (CMR), 22.33 and aids to navigation (AtoN), 22.25, 22.26 antennas, 22.10 to 22.12 Automatic Identification System (AIS), 22.2, 22.8 integration with, 22.23 to 22.25 cost of, 22.3 detection performance, 22.4 to 22.6 detecti on and processing, 22.13 to 22.15 display, 22.21 early days of, 22.31 to 22.33 environmental conditions, 22.3 international standards for, 22.7 to 22.10 magnetrons for, 10.16 precipitation and sea clutter, 22.5 racons and, 22.26 radar beacons and, 22.25 radar target enhancers (RTEs), 22.27 RF head (transmitter and receiver), 22.12 to 22.13 search and rescue transponders, 22.27 solid-state, 22.16 to 22.17 target tracking, 22.17 to 22.19 user interface, 22.19 to 22.22. validation testing of, 22.28 to 22.29 vertical lobing in, 22.6 to 22.7 Class of (amplifier) operation, 11. 18 to 11.20 Clouds, attenuation in, 19.7 to 19.8 CloudSat, 18.63, 19.39 Clustered-cavity klystron, 10.12 to 10.13 Clutter amplitude characteristics, 2.17 attenuation, in MTI, 2.20 to 2.21 characteristics for MTI, 2.10 to 2.19 exponential model, 2.12 to 2.16 in ground penetrating radar, 21.5, 21.10 maps, 2.83 to 2.87, 6.23, 7.19 models, for ground echo, 16.29 to 16.34 MTI filter design, 2.33 to 2.46 optimum filter design, 2.25 to 2.33 point scatterers, 2.18 to 2.19 in pulse doppler radar, 4.14 to 4.24 reflectivity, 2.17 to 2.18 Clutter-limited detection in pulse doppler, 4.48 Coaxial magnetron, 10.14 to 10.15 Coaxitron, 10.21 Cobra Dane radar,  8.36 Coherent processing, and ECCM, 24.34 to 24.35 Coherent Processing Interval (CPI), 2.7 Coherent on receive, 10.14. 
 The region of unambiguous range may be extended considerably by utilizing two separate  CW signals dilTering slightly in frequency. The unambiguous range in this case corresponds to  a half wavelength at the difference frequency.  The transmitted waveform is assumed to consist of two continuous sine waves of  frequency .f1 and .f~ separated by an amount 11f For convenience, the amplitudes of all signals  arc set equal to unity. 
 VERTICAL INCI 
 HORN TRIPLE 
 Soc. Pl10to-Optica/ Instrumentation Engi­ neers, vol. 128, "Effective Utilization of Optics in Radar Systems," pp. 
 D. H .. and E. 
 The curve of Fig. 13.10 illustrates the behavior of land clutter at \ow grazing angles. 38 The  value of a0 decreases with decreasing grazing angle until, in this case, at about 3.5° the value of  a0 actually increases as the grazing angle is lowered. 
 • X 6"- 6//.,. /./x I dI. I 6, I-700':-----:5:----:-'10=----:-':15=----:::-20=-------:2='=5:------:3='=0::------:3:':5:---4="=0:----::4"=5----='50 Windvelocity(knots) (b) Figure13.4Medianvalueof0'0asafunctionofwindspeed,forXbandand10°grazingangle.(a)Vertical polarizarion, (b)horizontal polarization. 
 This other technique, which is discussed in  Sec. 8.7. is a method for generating multiple receiving beams at a single frequency and can be  considered more like the stacked-beam radar than a frequency-scan height finder. 
 FUZZY SYSTEMS AND IN 
 The shorter the pulse with τ (or the broader  the spectrum of the transmitted pulse) and  the narrower the aperture angle are, the  smaller the resolution cell, and the higher  the interference immunity of the radar  station is.c0 = speed of light   τ = transmitters pulse width    Sr = range resolution as a distance between the tw o targets       Figure 15: Two aims, when the spacing is large enough     Figure 14: Two aims with t oo small spacing   c0 = speed of light   Btx = band width of the transmitted pulse    Sr = range resolution as a distance between the two targets       Figure 16: The resolution cell  . Radartutorial (www.radartutorial.eu)   11    Figure 16: Pattern of a highly directional antenna  compared with a ball -shaped isotropic pattern  Theoretical Maximum Range Equation   The radar equation repre sents the physical dependences of the transmit power, that is the wave  propagation up to the receiving of the echo -signals. Furthermore one can assess the performance  of the radar with the radar equation. 
 Radar System Engineering  Chapter 12 – Selected Radar Applications  147          Figure 13.16  Block diagram and inner -view of a 94 GHz FM -CW ACC Radar sensor, IAF  (Fraunhofer Institut Angewandte Festkörperphys ik) ERA9401     MMICs of 76 GHz will be employed in the next generation, approximately 2003, as shown in Figure 13.17.   . Radar System Engineering  Chapter 12 – Selected Radar Applications  148     Figure 13.17  Concept of a highly integrated (3 MMIC) ACC Radar sensor. 
 AES-7, March 1971. 19. Monzingo, R. 
   
 H., and D. Middleton: A Theoretical Comparison of the Visual, Aural, and Meter  Reception of Pulsed Signals in the Presence of Noise, J. Appl. 
    (  
 There can be many variations of these three classes,  as illustrated in Ref. 11.  I. 
 MacArthur: Digital Pulse Compression Radar Receiver, APL Technical Digest,  vol. 6. pp. 
 The digital commands may be used directly by digital attenuators or converted to voltage or current for control of diode attenuators or variable-gain amplifiers. Digital control permits calibration of each attenuation to determine the difference between the actual at- tenuation and the command, by injecting a test pulse during dead time. This is essential in monopulse receivers which compare the echo amplitudes received in two or more beams simultaneously to accurately determine the target's position in azimuth or elevation. 
 , &U  AND 0 3 #ALLAHAN  h3ATELLITE ALTIMETRY v IN  3ATELLITE !LTIMETRY AND %ARTH 3CIENCES  , 
 D. H. Sinnott and G. 
 If the limiting is proper, the false-alarm rate should not change. However, target signals in the absence of noise are unaffected, as they do not change the total energy present in the broad doppler spectrum sufficiently to change the AGC level or reach the limiting level. Similar remarks apply to the speedgate as well. 
 373-385.  7. Cutronf. 
 Although this method isofmore recent origin than the sine-cosine method, has not been sohighly devel- oped, and has nothad such thorough test% itappears tobemtisfactory. The sine-cosine method using multiple a-f signals isinprinciple quite simple and should prove satisfactory. Although ithas been successfully operated inanactual system (not atthe Radiation Labora- tory), the author isnot aware ofany extensive tests inthe presence of interference. 
 388 THEMAGNETRON ANDTHEPULSER [SEC. 10.11 harmful only inthose radars which detect moving targets (see Chap. 16) bycomparing successive pulse phases. 
 ING THE TIME SERIES DATA FROM THE RECEIVERS INTO THE NATURAL RADAR DOMAIN DIMENSIONS OF GROUP RANGE BASED ON TIME DELAY   DIRECTION OF ARRIVAL BEAM SPACE   AND DOPPLER FREQUENCY  HOPEFULLY SEPARATING THE ECHOES OF INTEREST FROM UNWANTED CLUTTER AND NOISE 4HE STANDARD TOOL FOR THIS DECOMPOSITION IS THE &&4  AT LEAST IN OPERATIONAL SKYWAVE RADARS  IN PART BECAUSE IT IS COMPUTATIONALLY QUITE FEASIBLE TO ANALYZE THE INCOMING SIG 
 DOPPLER #OUPLING  4HE ,&- WAVEFORM EXHIBITS RANGE 
 vol.36,pp.222-226, April, 1964. 66.Milne.K.:TheCombination ofPulseCompression withFrequency Scanning forThree-Dimensional Radars.RadioElectronic Engr.,vol.28,pp.89-106,Aug.,1964. 67.Croney. 
 FED ARRAY IS   "ANDWIDTH  BEAMWIDTH  #7   nL LG  WHERE KG IS THE WAVEGUIDE WAVELENGTH (OWEVER  FROM THE VIEWPOINT OF SIDELOBES  THIS CRITERION MAY BE UNACCEPTABLE &OR  A LOW 
 The loss in signal energy when operating with the  J3 Ikssel component is repor~ed~.~~.~~ to be from 4 to 12 dB. Altt~ough two separate transmit-  ting and receiving atiterinas rnay be used, it is not necessary in many applications. A single  anterlna with a circltlator is stiowri in the block diagram of Fig. 
 The average total power received from allthe raindrops that contri- Imte tothereturn atagiven range isthesum ofthereturn powers ofthe individual drops. The return po}vers, not the return fields, must be addedl be’cauw the random distribution ofraindrops inspace results in random phases oftheindividual contributions. The cross section uoforraindrops isthat ofasmall sphere oflarge dielectric constant (Sec. 
 ING OR NEAR THE SURFACE  AND SEARCH AND RESCUE 4RACKING MAY BE PRELIMINARY TO ATTACK WITH ANTISHIP WEAPONS !LTHOUGH MOST SHIPS ARE LARGE RADAR TARGETS  THEY MOVE RELA 
 0ACKARD !PPLICATION .OTES  (IGH &REQUENCY 4RANSISTO R 0RIMER  0ART   4HERMAL  0ROPERTIES  P   ( #OOKE  h-ICROWAVE TRANSISTORS THEORY AND DESIGN v  0ROCEEDINGS OF THE )%%%  VOL    PP n  !UGUST    6ENDOR TRANSISTOR DATASHEET  )NTEGRA 4ECHNOLOGIES  )NC  WWWINTEGRATECHCOM  6ENDOR TRANSISTOR DATASHEET  4YCO %LECTRONICS  -! 
 3.3. Denoising of the RCS curve When we extract the RCS curve by using the real data, the amplitudes are not 0 in angles which do not scatter the waves. These RCS amplitudes are regarded as noise in the RCS curves of targets. 
 FIES HOW WELL THE ANALOG )& MATCHED FILTER COMPARES TO THE IDEAL MATCHED FILTER FOR THAT POINT IN THE RECEPTION CHAIN 1UANTIZATION .OISE ,OSS  4HIS LOSS IS DUE TO THE NOISE ADDED BY THE !$ CONVER 
 The simplest specular absorber is the Salisbury screen , which is a thin resistive  sheet mounted a quarter wavelength above the metal surface to be hidden from a  radar.67 The design works best for incidence normal to the sheet, and if it can be manu - factured with a resistivity of 377 ohms per square (the impedance of free space) all the  power in the incident wave is transferred to the sheet and none is reflected. However,  the single-sheet Salisbury screen suffers several limitations. Its thin sheets and low- loss spacers are fragile, its 20-dB bandwidth is barely 25%, and its performance dete - riorates progressively as the angle of incidence moves away from normal incidence. 
 Clark, W. P.: A High Power Phase Shifter for Phased-Array Systems. /l:fE Tram., vol. 
 ZONE MEASUREMENTS v )%%% 4RANS  VOL !0 
 Similartechniques havealsobeenproposed forcooperative targetsbydeliberately pro­ vidingthetargetwithapassivetransponder employing microwave diodes.49•so Another relatedtargeteffectthatmightbeutilizedfortargetrecognition istherandom modulation ofthescattered signalcausedbythemodification ofthecurrentdistribution on ametaltargetthatresultsfromintermittent contacts onthetarget,67 Thismodulation can bedetected byexamining thefrequency spectrum inthevicinityofthereceived carrier.The acronym RADAM, whichstandsforradardetection ofagitated metals,hassometimes been usedtodescribe thiseffect.69 Inversescattering. Inprinciple, thesizeandshapeofatargetcanbefoundbymeasuring the hackscattered field,orradarcrosssection,atallfrequencies andallaspects.Itisnotpossible, ofcourse,toobtainsuchcomplete information, buttheprocesscanbeapproximated by measuring thebackscatter atafinitenumberoffrequencies andaspects.Thenameinverse scatterillgSIf'hasheenusedtodescribe thismethodforobtaining thetargetsizeandshape,and thusprovide ameansfortargetclassification. Theuseofhigh-range-resolution radarfor profiling atarget,andtheinversesynthetic aperture radarmentioned abovearetwopractical exampiesoftargetclassification methods thatmightbecalledapproximations ofinverse scattering. 
 TION WITH BASEBAND !$ CONVERSION  ARE INCLUDED FOR ILLUSTRATION IN &IGURE   THOUGH IN GENERAL  RECEIVERS WILL NOT INCLUDE BOTH TECHNIQUES 0RIOR TO THE AVAILABILITY OF AFFORD 
 .. ·---·----------··  ' available noise power from an equivalent resistance (9.12a)  or = Fc~ToBnGc = F G = Fe  tr k To B" c c L, (9.12b)  · where Fe = crystal mixer noise figure and Le 1/Gc = conversion loss. The noise temperature  ratio of a crystal mixer varies approximately inversely with frequency from about 100 kHz (the  exact value depends upon the diode25) down to a small fraction of a hertz. 
 Barton, D. K.: "Radars, vol. 4, Radar Resolution and Multipath Effects," Artech Iloilse, inc.,  l)ctlllum, Muss, 1975. 
 ÓÈ°Ó{  2!$!2 (!.$"//+  4O ASSIST THE !2%03 USER  THESE AND OTHER INPUT WINDOWS HAVE MANY hCANNEDv  DEFAULT VALUES COMBINED WITH MANY UNIT OPTIONS /NE EXAMPLE IS THE TRANSMITTING  ANTENNA PATTERN !0- WILL CONSIDER THE FULL ANTENNA PATTERN OF THE TRANSMITTING ANTENNA  &)'52%   !2%03 RADAR WINDOW &)'52%   !2%03 TARGET WINDOW.   4(% 02/0!'!4)/. &!#4/2  &0  ). 4(% 2!$!2 %15!4)/.   ÓÈ°Óx !2%03 PROVIDES SOME BASIC hCANNEDv ANTENNA PATTERNS SUCH AS OMNI  3IN88  COSE 
 J., J. H. Gutman. 
 IVEII’YORKANDLONDON !JIcGRA W-HILL BOOK COMPANY,INC. 1947 {/. ,,))../”t iV’,f :. 
 A target located at the maximum of a  A/4% Figure 12.2 Vertical lobe structure caused by the presence  of a plane reflecting surface.  PROPAGATION OFRADAR WAVES443 (12.2)assumes thath,~"0'Thephasedifference corresponding tothepath-length difference is 2rr.2ha1l,.11d=---~-radiansAR TothismustbeaddedthephaseshifttjJrresulting fromthereflection ofthewaveatM,whichis assumed toberr.radians,or180°.Thetotalphasedifference between thedirectandtheground­ reflected signalsasmeasured atthetargetis (12.3) (12.4)Theresultant oftwosignals, eachofunityamplitude butwithphasedifference tjJ.is [2(I+cosIII)J112.Therefore theratioofthepowerincident onthetargetatBtothatwhich wouldbeincident jfthetargetwerelocatedinfreespaceis 2 _2(_4rr.lzah')=4.22rr.lIall, '1- 1 cos).R SinAR Because ofreciprocity. thepathfromtargettoradaristhesameasfromradartotarget.The powerratioattheradaristherefore (12.5) (12.6) maximaTheradarequation describing thereceived echopowermustbemodified bythepropagation factor t]4ofEq.(12.5).Sincethesinevariesinmagnitude from0to1,thefactor t]4variesfrom oto16.Thereceived signalstrength alsovariesfrom0to16;hencethefourth-power relation hetween rangeandechosignalresultsinavariation ofradarrangefrom0to2timestherange ofthesameradarinfreespace. 
 The gaussian pulse is well suited for this purpose since its spectrum decays rapidly on  either side of the carrier frequency. Its rrns range error is  r - 1.18  ST R - - I. 18(iEii;jiii - njj(2Em;)ii? gaussian pulse  \vlicrc n is tlic tialf-power haridwidth of the gaussian-pulse spectruni. 
 One of the advantages of an integral STC using  the diode limiter rather than a separate RF STC, is that no additional insertion loss is suffered  for the STC other than that inherent in the TR-limiter itself.  In a solid-state limiter, it is also possible to couple a noise diode into the output to  provide a convenient source for checking receiver noise-figure."  Several hundred hours of life is considered typical for conventional TR tubes that use an  active keep-alive discharge. However, a duplexer using a passive radioactive-primed TR and  diode limiter is capable of perhaps five thousand hours of life,50 with predictionsfof up to four  years of continuous ~peration.~'  REFERENCES  1. 
 Tile cclioes from clear-air turbulerice are quite weak and are seen only by high-power  radar. The basic tlleory for scattering from 1iomogeneous and isotropic turbulent media was  first given by Tatar~ki."'.''~ The scattering mechanism from turbulent media is similar to  f3ragg scatter in that a radar of wavelength A scatters from that particular component of tlie  turbuletice wit11 eddy sizes equal to A/2. The volume reflectivity, or radar cross section (m2) per  ci~hic volume. 
 Van Nostrand Company, Inc., Princeton, NJ., 1955.  56. Cross, D. 
 Itsgeneral direction isknown and fresh information astoitsdistance ishardly needed more than afew times a second. Observation 100 times asecond isactually employed inradar altimeters, tomake possible thereduction ofcertain errors byaveraging, but even sotherate ofinformation transmission issmall. Second, there arethesituations inwhich, though alittle information may beobtained with ease, alotisimpossible toobtain. 
 The transition  between one and the other takes place at a wavelength of about 2 cm, so the smaller  capillary waves supply the surface fine structure while gravity waves make up the  larger and most visible surface structures. Sea waves have their origin primarily in the  wind, but this does not mean that the “local” wind is a particularly good indicator of  what the wave structure beneath it will be. In order to arouse the surface to its fully  developed  or equilibrium  state, the wind must blow for a sufficient time ( duration )  over a sufficient distance (  fetch ). 
 RANGE ERROR IS GREATLY INCREASED  NOT UNLIKE THAT OF A RADAR USING ANGLE DATA TO ESTABLISH CROSS 
 The limitation from this effect is 7 = 20 log (dt/T) (5.4) where dt is the time jitter and T is the pulse width. If pulse compression is used, T is still the transmitted-pulse width, not the compressed-pulse width. In addition, careful design must take into account interactions that can occur as a result of the many cascaded stages of solid-state amplification. 
 The more usual method ofrepresenting the circuit isshown inthe lower diagram ofFig. 13.10, where the adding and amplifying areindi- cated together. -++$b+Tube Tube Impedance >ZImpedance <Z (a) (b) (c) Fm.13,11 .—Cathode feedback. 
 NING WAS CALCULATED FOR DIPOLES ABOVE A GROUND PLANE )N SPITE  OF INCREASED MUTUAL COU 
 PULSE AND WILL  THEREFORE  CANCEL IN THE -4) FILTERS 7HEN THIS COHERENCE OF ALL FREQUENCIES IS NOT MAINTAINED  CLUTTER RESIDUE WILL OCCUR AND MUST BE QUANTIFIED TO DETERMINE IF IT IS AT AN ACCEPTABLE LEVEL /NE OF THE PROMINENT PLACES IN WHICH RESIDUE CAUSED BY UNSYNCHRONIZED LOCAL OSCILLATORS HAS SHOWN UP IS IN PULSE 
 62, pp. 724–725, 1974. 159. 
 MOl'ingclutterandstationary radar.Thediscussion inthissectionhasbeenconcerned with theoperation ofanMTIradarwhentheclutterdoppler-frequency wasnotatdcbuthadsome finitevaluehccausc ofthemotionofthevehiclecarrying theradar.The.clutterdoppler frequency willalsobeotherthanatdciftheradarisstationary andtheclutterhasacompo­ nentofvelocityrelativetotheradar,aswhentheclutterisduetorainstorms,chaff.orbirds. ManyoftheAMTItechniques described abovecanbeappliedtothestationary MTIradar thatmustcopewithmovingclutter.Mostconventional techniques fail,however. whenboth stationary andmovingclutterarewithinthesamerangeresolution cell.Insuchsituations the MTIsignalprocessor musthavethecapability ofplacingseparate rejection notchesatthe dopplerfrequcncicsofthee1u!leI'.7 I.72 4.12OTHER TYPESOFMTl Two-frequency MTI.78.79ThefirstblindspeedofanMTIradarisinversely proportional tothe carrierfrequency. 
 W.: MTI Radar, chap. 17 of" Radar Handbook," M. I. 
 I.: "Introduction to Radar Systems," 2d ed., McGraw-Hill Book Com- pany, New York, 1980. 10. Brown, B. 
 144. E. Conte, A. 
 Publ. no. 105, "Radar-Present and Future," Oct. 
 Some sources of discrete sidebands are ripple on power supplies and  the pickup of digital clocks. It is desirable to keep the integrated discrete sidebands  below noise at the CFAR input to prevent detecting these discretes and producing false  alarms. All coherent and postdetection integration must be accounted for when we  specify discrete phase noise requirements. 
 SIGHT u  5SUALLY UNIQUE MAY HAVE SIMPLE GROUND 
 MIZE THE LINEAR OPERATING REGION  WITH LIMITERS USED ONLY TO HANDLE EXCESSIVELY LARGE SIGNALS THAT INEVITABLY EXIST UNDER WORST CASE CONDITIONS #HARACTERISTICS  4HE IDEAL LIMITER IS PERFECTLY LINEAR UP TO THE POWER LEVEL AT  WHICH LIMITING BEGINS FOLLOWED BY A TRANSITION REGION BEYOND WHICH THE OUTPUT POWER REMAINS CONSTANT )N ADDITION  THE INSERTION PHASE IS CONSTANT  FOR ALL INPUT POWER LEV 
 During each. 504 THERECEIVING SYSTEM—INDICATORS [SEC. 13.9 positive excursion ofAthe resistance extracts asmall charge, which is replaced bythe diode onthe next negative excursion.’ The clampigg can bedone atthepositive extreme byreversing thediode. 
 The operation ofthis system was much more difficult than might be inferred from this brief description. IftheCH stations had been perfect, itwould still have been difficult tointerpret some hundreds ofplots every minute, allsubject tovariable delays and tothe personal errors ofthe observers. Quite trivial difficulties proved surprisingly hard toover- come. 
 ÓÓ°Óä  2!$!2 (!.$"//+  4OUCHSCREEN TECHNOLOGY IS SOMETIMES EMPLOYED )NCREASINGLY  SYSTEMS ALSO INCLUDE  A FULL ALPHANUMERIC KEYBOARD TO ALLOW EASY INPUT OF USER 
 BASED 3!2 DATA  .OTE THAT BOTH LOOKS AND RESOLUTION REQUIRE SUPPORT IN BANDWIDTH )T FOLLOWS THAT 1 3!2 IS PROPORTIONAL TO THE PRODUCT OF THE RANGE AND AZIMUTH BANDWIDTHS  HENCE  PROPORTIONAL TO THE TWO 
     "       "      "       "      
 45. Headrick, J. M., J. 
 CHAPTER 20 HEIGHT FINDING AND 3D RADAR David J. Murrow General Electric Company 20.1 HEIGHTFINDINGRADARSAND TECHNIQUES Early Radar Techniques for Height Finding. Early radar techniques em- ployed to find target height were classified according to whether or not the earth's surface was used in the measurement. 
 This acceleration is unknown and must be estimated.  During exo-atmospheric flight, the object is falling with the known acceleration of  gravity. During endo-atmospheric re-entry, the target continues to fall but experiences a  drag acceleration due to its ballistic coefficient (an unknown target parameter related to  the shape and mass of the target). 
 ERROR VOLTAGE AND PERFORMS THE TASK OF MOVING THE ANTENNA BEAM IN A DIRECTION THAT WILL REDUCE TO ZERO THE ALIGNMENT ERROR BETWEEN THE ANTENNA AXIS AND THE TARGET &OR TWO 
 U.S.S.R. Cosmos 1500 Side-Looking Radar.38 39 The U.S.S.R. launched the Cosmos 1500 oceanographic satellite on Sept. 
 RANGE LOCATIONS OF SCATTERERS $OWN 
 FREQUENCY RESPONSE AND TEND TO ACT AS HIGH 
 Toavoidambiguities, thebackward radiation isusuallyeliminated byplacinga renecting screenbehindthearray.Thusonlytheradiation O'lertheforwardhalfofthe antenna (-900:::;(}:::;90°)needbeconsidered. Theradiation patternisequaltothenormalized squareoftheamplitude, or G(0)=J~_aJ~=sin2[Nrr(dIA) sin0] aN2N2sin2[rr(dIA)sin0] Ifthespacink'between antenna elements isAI2andifthesineinthedenominator ofEq.(8.4) isrcplaced byitsargument, thehalf-power beamwidth isapproximately equalto 102OB=----­N(8.5) (8.6)Thefirstsidelobe,forNsufficiently large,is13.2dBbelowthemainbeam.Thepatternofa uniformly illuminated arraywithelements spacedAI2apartissimilartothepatternproduced hyacontinuously illuminated uniform aperture [Eq..(7.16)]. Whendirective elcments areused,theresultant arrayantenna radiation patternis G(O)=G(0)Si!.12 (1}'~(d~~L~i_~_qL =G(O)G(0) eN2sin2[rr(c/IA)sin0] ea whereGe(O)istheradiation patternofanindividual element. 
 U.S.Dept.ofAgriculture.. CHAPTER  FOURTEEN  OTHER RADAR TOPICS  14.1 SI'N'I'I-IE'I'IC APEH'I'URE RADAR'  A synthetic aperture radar (SAR) achieves high resolution in the cross-range dimension by  taking advantage of the motion of the vehicle carrying the radar to synthesize the effect of a  large antenna aperture. The imaging of the earth's surface by SAR to provide a maplike  display can be applied to military reconnaissance, measurement of sea state and ocean wave  conditio~is. 
 The relationship between d  (∆f) and a variation in terrain altitude d  h is  | || ( )|δλ δ φ πhR nL=∆ 2   (antennas separated vertically) (17.58) InSAR for terrain elevation measurement can also be performed by an aircraft with  two antennas separated horizontally  (perpendicular to the flight path) by L. The aircraft  is banking at angle g  > 0 and collecting data from the flat ground at grazing angle y  (Figure 17.15). Then the effective aperture (perpendicular to the LOS) is L sin (y + g  )  instead of Lcos y. 
 Acoust. Soc. Am. 
 119.Cohcn,A.,andA.Smolski: TheEffectofRainonSatellite Communications EarthTerminal Rigid Radolllcs, Miaml'm'c J.,vol.9.pp.111-121, September, 1966. 120.Weigand, R.M.:Pc,l'orlllancc ofaWatcr-Repcllcnt Radolllc Coating inanAirport Surveillancc Radar,I'roc.IEEE,vol.61,pp.1167116R,August, 1973. 121Andcrson, I.:Measurcmcnts of20-Cillz Transmission Through aRadome inRain,IEEETI'l/IIS., vol.AP-23,pp.619622,Scptcmbcr, 1975. 
 Third, the RCS curves of the targets are obtained. Finally, the aspect entropy of each target is calculated. The constant false-alarm rate (CFAR) or generalized likelihood ratio test (GLRT) [ 23,24] methods can be used to extract the targets from the image. 
 Army Signal Corps report in 1943. It presents a fairly detailed range equation and contains information on evaluating some of the more problematical factors, such as multipath interference and minimum detectable signal, within the limitations of the then-available knowledge. The signal detection process was assumed to be based on visual observation of a cathode- ray-tube display. 
 To determine the generalized ambiguity function for a radar system, let a waveform f(f) be radiated. We consider the operations performed upon the re- ceived signals with the objective of determining the radar reflectivity of the ter- rain being mapped. The function f(f) may assume a variety of forms and may be a succession of short signals. 
 850–858, 2003. 62. ITT Avionics Division, Electro-Physics Laboratories, EPL Model ATL-75 Transmitter for  Radar and Communication, IR&D Project Rept. 
 Amplitude noise, to  some extent, affects all types of radars in probability of detection and tracking radar  accuracy.32–36 One effect on all types of tracking radars is the interrelation between the  low-frequency spectrum of amplitude noise, the AGC characteristics (which determine  to what extent the slow fluctuations are smoothed), and the angle noise. The effects on  angle noise are described later in this section, where it is described why a fast-acting  AGC is generally the preferred choice for maximizing overall tracking accuracy . High-frequency amplitude noise causes errors only in conical-scan or sequential lob - ing tracking radars because the effects are eliminated by the monopulse techniques. 
 This is followed by several chapters on the major subsystems of a radar: the receiver, transmitter, solid-state transmitters, reflector anten- nas, phased array antennas, data processing, ECCM, and pulse compres- sion. Next are discussions of the target cross section and the nature of the radar echoes from the ground and the sea. The various types of radar systems are then discussed: CW and FM-CW, MTI, AMTI, pulse doppler, tracking, missile guidance, height finding and 3D, and synthetic aperture radar. 
 Lyons, Understanding Digital Signal Processing , 2nd Ed., Upper Saddle River, NJ:  Prentice Hall, 2004.  3. J. 
 Ê,,9- 4HE PHENOMENON OF FOCUSING AN ARRAY IS THE RESULT OF THE ENERGY FROM EACH ELEMENT ADDING IN 
      
 FIG. 16.2 Defining geometry: a0 = antenna pointing angle; a = line-of-sight angle; 9 = angle from antenna centerline; V8 - aircraft ground speed; Vr = radial velocity of point target; V3 — radial velocity along antenna centerline (boresight); i|i0 = antenna azimuth angle; vji = azimuth angle; R = ground range to point target; H = aircraft height."POINT" TARGETANTENNACENTERLINE LINE OF . R/H FIG. 
 PENETRATION 3!2 0OLARIMETRIC 3!2  5SUALLY WHEN A RADAR TRANSMITS A  PULSE AT A PARTICULAR POLARIZA 
  
 (There should be at least 2 pulses per scan rather  than one, in order to avoid a large scanning loss.) On the next scan, one-tenl.h second later, two  additional pulses are received that are decorrelated from the previous two pulses so that an  integration improvement can be obtained. The number of pulses processed by the slow-speed  and the high-speed antennas are the same. The 20 rpm antenna receives 60 pulses per scan  with a 3-second rotation period. 
 A., and T. W. Miller: "Introduction to Adaptive Arrays," John Wiley & Sons, New York, 1980. 
 This must be compensated by greater transmitter power. In  short. tlie use of bistatic radar to obtain other than fence coverage usually results in more  complicated and less efficient systems. 
 (ALL    * 0 "URG  h4HE RELATIONSHIP BETWEEN MAXIMUM ENTROPY SPECTRA AND MAXIMUM LIKELIHOOD   SPECTRA v 'EOPHYSICS  VOL   PP n    * #APON  h(IGH RESOLUTION FREQUENCY 
 R. H. Allen, D. 
 -ADJAR  h# 
 With fast-rise-time, high-power RF sources, the receiver protector may be required to  self-limit in less than one nanosecond. This can be achieved with fast-acting PN (varactor)  diodes. A number of diode stages, preceded by plasma limiters, might be employed in such a  receiver protector. 
 GET DOPPLER IS SUCH THAT IT STILL COMPETES WITH THE SIDELOBE CLUTTER  (OWEVER  IN THOSE DOPPLER REGIONS FREE OF SIDELOBE CLUTTER  AS SHOWN IN &IGURE  AND &IGURE   TARGET DETECTABILITY IS LIMITED ONLY BY THERMAL NOISE  INDEPENDENT OF RADAR ALTITUDE  SPEED  AND SIDELOBE LEVEL 4HIS REQUIRES SYSTEM STABILITY SIDEBANDS TO BE WELL BELOW NOISE FOR THE WORST 
 vol. 11. pp. 
 Meteorol., vol. 12, pp. 847-854, 1973. 
 ERAGE OF n IS ACHIEVED BY ROTATING THE ARRAY AT A NOMINAL SURVEILLANCE RATE ! UNIQUE FEATURE OF THE !.403 
 STAGE VELOCITY MEASUREMENT PROCESS &IRST  THE SURFACE IS AUTOMATICALLY ACQUIRED IN RANGE 3ECOND  A FINE RANGE MEASUREMENT IS MADE  OFTEN USING MONOPULSE DISCRIMINANTS AND RANGE CENTROIDING SIMILAR TO THAT SHOWN IN %Q  4HIRD  A LINE 
 MTI is a necessity in high-quality air-surveillance radars that operate in the presence of  clutter. Its design is more challenging than that of a simple pulse radar or a simple CW radar.  An MTI capability adds to a radar's cost and con~plexity and often system designers must  accept compron~ises they might not wish to make. 
 POLARIZED LABORATORY STUDY  OF MICROWAVE BACKSCATTERING FROM WATER WAVES  PART  3HORT GRAVITY WAVES WITHOUT WIND v )%%% * /CEANIC %NG  VOL /% 
 J. F. Ramsey, “Lambda functions describe antenna/diffraction patterns,” Microwaves , p. 
 The final result connecting rand R2isthefollowing: (r),~,=$,(R,),m, (6) where f,isthePRF, Athewavelength, and kafactor that deper.ds onthe wind speed and type ofterrain. Measurements ofthe ratio of(r),m to (R),~have been made byH.Goldstein.’ The following table gives typical values extrapolated from the experimental figures which were obtained using arepetition rate of333/see. The voltage ratio offixed to variable clutter isalso given. 
   .OVEMBER   !$ 
 Theforward-wave CFAcanoperateoverahroadrangeoffrequency witha constant anodevoltage, withonlyasmallvariation intheoutputpower.Ontheotherhand, thepoweroutputofabackward-wave CFA,withaconstant anodevoltage, varieswith frequency. Foratypicalbackward-wave CFA,thepoweroutputcanvary100percentfora10 percent change infrequency.1s Itispossible, however, withconventional modulator techniques, tooperatethebackward-wave CFAoverawidebandwithlittlechangeinoutput power.Thetypeofmodulators normally usedwithcathode-pulsed CFAscanreadilycompen­ sateforthepowervariation withfrequency ofabackward-wave CFAandholdthevariation of outputpowerwithinacceptable levels.Thisisaresultofthenatureofthedispersion character­ isticsofsuchtubes.Forexample, withaparticular X-bandVarianbackward-wave CFA,16a constant-voltage modulator produces avariation inoutputpowerfrom505kWat9.0GHzto 240kWat9.5GHz,achangeof3.2dB.Aconstant-current modulator withthesametube resultsinapowervariation ofonly0.3dBoverthesamefrequency range.Sincemostpractical modulators areneitherconstant-current norconstant-voltage devices,actualperformance is somewhere inbetween. Amodulator withaninternal impedance oft50ohmswillresultin bothcurrentandvoltagevariations asafunction offrequency whenusedwiththeaboveCFA, butthepoweroutputvariesonly1dB.Thusitdoesnotmattersignificantly tothemodulator designer whether theCFAisofthebackward-wave ortheforward-wave typeaslongas cathode pulsingisusedwitheitheraline-type modulator oraconstant-current hard-tube modulator. 
 TheDolph-Chebyshev weighting theoretically resultsinallsidelobes beingequal.Itisof academic interestonly,sinceitisunrealizable. TheTaylorisapractical approximation tothe Dolph-Chebyshev. Asuitable waveform mightbethecosine-squared onapedestal, asinthe Hamming function, forexample. 
  
 However, such solu- tions preclude a variable-PRF system other than in discrete, accurately known steps. Although synchronization of the PRF and the IF passband is usually neces- sary, synchronization at RF is not usually required. The harmful harmonics are of a much higher order and therefore are much smaller. 
 The frequency response of a single-delay-line canceler (Fig. 4.7) does not  always have as broad a clutter-rejection null as might be desired in the vicinity or d-c. The  clutter-rejection notches may be widened by passing the output of the delay-line canceler  through a second delay-line canceler as shown in Fig. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 19.46  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 120. 
 C.Purves,andP.Watkins: Propagation Through an F1cvated Duct:Tradewinds III,IEEETraIlS.,vol.AP-12,pp.479-490, July,1964. .~I.Rattan.L.J.:"RadarObservation oftheAtmosphere:' University ofChicago Press,Chicago. 1973. 
 HEED -ARTINS LONG 
        
 (Thermserrorofanangle measurement isproportional tothebeamwidth.) Anolher limitation islheeffectofmultipath duetoreflection fromtheearth'ssurface.alsoaconsequence ofthebroadfanbeams.Theeffect ofllluitipath issimilar 10theciTedofglinldiscussed inSec.5.5fortracking radars.TheIllulli­ patherrorcanbequitesevereandmaketheanglemeasurement inmanycasesalmostuseless, asdiscussed inSec.22.JofRef.J2.Thiseffectwillgenerally belesssevereoverlandthanover waterhecause ofthesmallerreflection coefficient ofland.Iftheantenna beamcanbetiltedup soastoreducetheillumination ofthesurface.oriftheantenna elevation patterncanbe designed tohaveasharpcutoffontheunderside ofthebeam.theeffectofsurfacereflections is reduced andthemonopulse anglemeasurement isimproved. However, thisreducesthecover­ ageoftargetsatlowelevation angles. Sincetheproblem ofmultipath errorsoccursforantenna beamswhichilluminate the surface. 
 Young: The Ohio State University Compact Radar Cross Sec- tion Measurement Range, IEEE Trans., vol. AP-32, pp. 1218-1223, November 1984. 
 #/5.4%2-%!352%3   Ó{°xÇ "- "ALLISTIC -ISSILE #!20%4 #OMPUTER !IDED 2ADAR 0ERFORMANCE %VALUATION 4OOL #&!2 #ONSTANT &ALSE !LARM 2ATE #/2$)# #/ORDINATE 2OTATION $IGITAL #OMPUTER #/32/ #ONICAL 3CAN 
 N.   . {°£n  2!$!2 (!.$"//+  WHERE  !I   )00 WEIGHT   a I a . 
 13.35  14. CW and FM Radar   ................................................... 14.1  14.1 Introduction and Advantag es of CW  ....................... 
 (Increasing azimuth resolution by broadening the antenna pattern, either by  reducing the aperture length or spoiling the beam, has the disadvantage of reducing  the antenna’s gain, which usually is not desirable for space-based SARs. In addition,  the PRF must be larger than the instantaneous doppler bandwidth, thus reducing the  allowable unambiguous range swath.) Going the other direction—smaller doppler bandwidth—leads to more coarse azi - muth resolution. The doppler bandwidth of the original signal history from a given  backscatterer may be reduced by the simple expedient of generating a shorter syn - thetic aperture than the canonical case. 
 The design of parameter h. 4.2. The First Azimuth Sidelobes in Elevation Must Be Outside the Integrating Range [−h,h] The zeroes of sin c (y/prime/ρa)occur at the points, y/prime m=±mρa(m=1, 2,···). 
 sible, inorder togetthemaximum possible change ofphase with change of range. The limit isreached when, atextreme range, the phase shift is27radians; ranges beyond this areambiguous. This condition leads totheinequality j,s$ (6)m., aresult that isentirely analogous tothe similar relation discussed in Chap. 
 An example of the measured  distribution of the apparent target angle of a small two-engine aircraft is shown in  Figure 9.22. A relatively long time sample is needed, since short time samples of data  can depart from the gaussian shape. Unusual targets may also depart from gaussian  distributed angle noise. 
 BASED TO EASE MAINTENANCE 5SED IN THIS WAY  THEY ARE KNOWN AS 6IRTUAL !)3 !TO.S  5P 
 Table 9.1 Radar CRT phosphor characteristics (after Berg26)  Phosphor Fluorescent color Phosphorescent color Persistence•  Pl Yellowish green Yellowish green Medium  P7 Blue Yellowish green Blue, medium short;  yellow, long  P12 Orange Orange Long  Pl3 Reddish orange Reddish orange Medium  Pl4 Purplish bbe Yellowish orange Blue, medium short;  yellowish orange, medium  Pl 7 Blue Yellow Blue, short; yellow, long  Pl9 Orange Orange Long  P21 Reddish orange Reddish orange Medium  P25 Orange Orange Medium  P26 Orange Orange Very long  P28 Yellowish green Yellowish green Long  P32 Purplish blue Yellowish green Long  P33 Orange Orange Very long  P34 Bluish green Yellowish green Very long  P38 Orange Orange Very long  P39 Yellowish green Yellowish green Long  • Persistence to 10 percent level: short= 1 to 10 µs; medium short= 10 µs to 1 ms;  medium= 1 to 100 ms; long= 100 ms to 1 s; very long= > 1 s. RECEIVERS, DISPLAYS, AND DUPLEXERS 357  Resolution on the CRT is limited by the phosphor characteristics as well as the electron  beam. A double-layer phosphor will hav:e poorer resolution that a single-layer phosphor. 
 1456-1459, October, 1956.  45. Monaghan. 
 "ETHELL  h7HAT DO WE NEED TO KNOW TO LAND ON THE -OON AGAIN  v  3CIENCE  VOL   PP n    + * 0ETERS  h#OHERENT 
 A distinction is made between radars with closely spaced antennas and radars with  widely spaced antennas because the former resemble the conventional monostatic radar more  than the type of bistatic radar to be discussed here.  Description. The bistatic radar is not a new concept. 
 6  (EASTCON Suppl.), pp. 366-373, November, 1967.  64. 
 Geosci. Remote Sens. 2015 ,53, 3460–3470. 
 This happens tobethe value forwooded terrain when A=3.2cmand. 654 MOVING-TARGET INDICATION [SEC. 1610 f,=500 and the wind velocity is25mph, asisshown inTable 16.2. 
 DAMENTAL USE OF 34# IS TO TAKE OUT THE DISTANCE 
 At Low Grazing Angles.  At low grazing angles, below mean sea slope angles  of about 10°, sea clutter takes on a different character. The sharp target-like clutter  peaks known as sea spikes  begin to appear on A-scope presentations,1,32,40,41 and  the probability distributions assume a different form.30,42 Figure 15.11 a and b show  the presence of sea spikes in 125-second time histories of returns from a fixed spot,  measured off the coast of Florida with a variable-resolution X-band radar looking  into moderate ( a) and calm ( b) seas at a 1.5° grazing angle.24 Notice that the appear - ance  of the sea spikes is very similar for both moderate and weak wind conditions,  although the amplitudes  differ by almost 40 dB, and the vertically polarized returns  appear to be somewhat broader, while the horizontally polarized returns are more  spiky, particularly for short pulses in calm seas. 
 Lind, Ci.: A Simple Approximate Formula for Glint Improvement with Frequency Agility, IEEE Trans.,  vol. AES-8, pp. 854-855, November, 1972. 
 The equivalence between time and space averaging in sea clutter measurements was discussed earlier, and in the case of clutter spectra the averaging times were all quite long (of the order of 10 to 20 min), which should be sufficient to stabilize the spectra for almost any resolution cell size. Spectra obtained with short averaging times disclose something of the origins of the clutter spectrum. Figure 13.15 is a sequence of 0.2-s spectra obtained by Keller et al.55 with a coherent vertically polarized X-band radar operating at a grazing angle of 35° and a resolution cell size of about 10 m2. 
 EARTH 
 PLER RADARS ARE OPERATED IN A SINGLE 02& MODE  COMPROMISING THE RADARS ABILITY TO UNAMBIGUOUSLY RESOLVE EITHER RANGE OR VELOCITY (OWEVER  THE PULSING SEQUENCE MAY USE A hDUAL 02&v MODE IN WHICH GROUPS OF CONSTANT 02& PULSES ARE TRANSMITTED OR A hDUAL STAGGERED  024v PULSE REPETITION TIME  TO RESOLVE BOTH RANGE AND VELOCITY AMBIGUITIES  !NOTHER APPROACH IS TO EMPLOY A TRANSMITTED PULSE SEQUENCE WITH RAN 
 All of these effects should be included when  computing the eclipsing and range gate straddle loss. Doppler Filter Weighting Loss.  This loss results from the increased noise band - width of the doppler filters that occurs because of filter sidelobe weighting. 
 Range information is extracted from the output of the sum channel  after amplitude detection.  Since a phase comparison is made between the output of the sum channel and each of the  difference channels, it is important that the phase shifts introduced by each of the channels be  almost identical. According to Page, 13 the phase difference between channels must be main­ tained to within 25° or better for reasonably proper performance. 
 Therefore, the corners of parabolic cylinder reflectors are  seldom rounded in practice. Shaped Reflectors.  Fan beams with a specified shape are required for a variety of  reasons. 
 I_7 polarization, 21.10 to 21.11 propagation, 21.6 to 21.13 reflections in, 21.9 to 21.10 resolution, 21.13 road thickness measurement, 21.37 to 21.38 and SAR, 21.13 signal processing, 21.30 to 21.35 soil suitability map, 21.20 from space, 18.59 to 18.62 systems, 21.20 to 21.21 velocity of propagation, 21.11 Ground plane, 14.31 Guard blanking loss, 4.44 Guard channel, in pulse doppler, 4.19 to 4.22 Gyrotrons, 10.3, 10.17 to 10.19, 10.26 H Hail, attenuation in, 19.11 to 19.12 Hail, detection of, 19.31 Height measurement, with InSAR, 17.30 to 17.33 Height measurement, with SAR, 17.27 to 17.33 HF, 1.15 HF over-the-horizon radar. See over-the-horizon radar High-medium PRF, 4.7 High-PRF pulse doppler, 4.7 to 4.8 High-PRF range-while-search, 4.36 Hi gh-PRF ranging, in pulse doppler, 4.34 to 4.35 High-resolution radar, 1.5 Hilbert transform, 6.43 to 6.44 HJ-1-C SAR, 18.13 Hot clutter, 24.43 Hybrid models for propagation, 26.16 to 26.17 Hybrid processors, 25.37 IIdentification friend or foe (IFF), integration with radar, 7.50 I/Q channels, 6. 31 to 6.35 Image-reject mixer, 6.13 Imaging radar ground echo, 16.55 to 16.56 Improvement factor, for AMTI, 3.8 Improvement factor limitations caused by staggering, 2.42 to 2.44 Improvement factor, for MTI, 2.19 to 2.20, 2.23 to 2.25, 6.17 to 6.18 Inductive output tube, 10.22 Infinite impulse response (IIR) filters, 2.33, 25.26 to 25.27 Insets, radar cross section of, 14.11 to 14.12 Instabilities in MTI, 2.65, 2.73 Instability limitations in MTI, 2.72 Instantaneous bandwidth, 6.9 Interclutter visibility in MTI, 2.22 Interacting multiple model (IMM) in ADT, 7.35 to 7.37 Interferometric SAR (InSAR), 17.5,   17.23 to 17.24 target height measurement, 17.30 to 17.33 International Maritime Organization (IMO), 22.1, 22.4, 22.8, 22.27, 22.28, 22.32 Interpolation filters, 25.28 Inverse Cassegrain, 9.25 Inverse SAR (ISAR), 5.23 to 5.24, 5.31 to 5.33, 9.37, 17.5 and ECCM, 24.51 to 24.52 Ionogram, 20.16 to 20.17 Ionosphere, 20.13 to 20.21 Ionospheric models, 20.19 to 20.20 Isodoppler contours in bistatic radar, 23.16. 
 [ CrossRef ] 10. Gerry, M.J.; Potter, L.C.; Gupta, I.J.; Van Der Merwe, A. A parametric model for synthetic aperture radar measurements. 
 Hildebrand: The NCAR Airborne Doppler Radar, Part III: Overview of Radar Design Details, Preprints, 23d Conf. Radar MeteoroL, vol. I, pp. 
 IEEE, vol. 58, pp. 731-743, May, 1970. 
 ERALLY A DOMINANT MECHANICAL DESIGN DRIVER BECAUSE IT DETERMINES THE ENVIRONMENT  THERMAL  VIBRATION  ETC   AND IT TYPICALLY DRIVES THE AVAILABLE SIZE  WEIGHT  AND POWER 37!0  FOR THE RADAR AND THE REFLECTOR ANTENNA 4ABLE  PROVIDES A QUALITATIVE COM 
 79. R. J. 
 Hansen (ed.). Academic Press, N.Y.. 1966. 
 Rev., vol. 28,  pp. 554-575, September, 1926. 
  CV J J J JFF      WHERE F KINC AND F KSCAT ARE THE INCIDENT AND SCATTERED RADIO WAVE VECTORS   KK \\F INC   V IS THE DOPPLER FREQUENCY   3 FJ IS THE SEA DIRECTIONAL WAVE SPECTRUM   C   IS THE  $IRAC DELTA FUNCTION  AND THE "RAGG FREQUENCY  V" IS GIVEN BY  V"GK K 
 Problems occurred mostly with older-style intercepting-grid linear-beam tubes because the hot grid may emit and produce residual beam current even if cathode current is cut off. Spurious Modes. The spurious modes listed in Table 4.1 are the ones most commonly present. 
 RANGE INSTRUMENTATION  THE TRACKING 
 .~2.Booker, H.G.:Elements ofRadioMeteorology: HowWeather andClimate CauseUnorthodox RadarVisionbeyondtheGeometrical Horizon, J.lEE,vol.93.pI.lIlA,pp.69-78,1946 . .~3.Saxton,J.A.:TheInnuence ofAtmospheric Conditions 'onRadarPerformance, J.11Ist.Navigation (Lc)/JdOlI). vol.II.pp.290303, 195R.. 
 The transmitter should provide sufficient power toensure clear signals, free from noise and interference, atthe maximum required range. In common with allcomponents, itmust have sufficient bandwidth toaccom- modate the band offrequencies present. The receiver should have a satisfactory noise figure, aproper bandwidth, and inmany cases must provide special means ofdistinguishing between desired and undesired signals bymethods analogous totheantijamming techniques described inSec. 
 HORIZON RADARS v  )%% 0ROC 2ADAR  3ONAR  AND  .AVIGATION  VOL   PP n    4 4HAYAPARAN AND 3 +ENNEDY  h$ETECTION OF A MANEUVERING AIR TARGET IN SEA 
 The only demand on the transmitter power is that it be  great enough to cause the clutter power at the radar receiver to be large compared to receiver  noise. If otherwise, Eq. (13.8) would not apply. 
 The reflected wave is polarized at right angles to the strips on the opposite side. This antenna is known as a Helisphere.35 If the scanning is in azimuth only, the height dimension of the reflector may be parabolic for perfect elevation focus. This is the parabolic torus,3'4 which has been used in fixed radar installations. 
 SUNSET PLASMA BUB 
 TIONAL ANTENNA  WHERE MISMATCH AFFECTS ONLY THE LEVEL OF THE POWER RADIATED AND NOT THE SHAPE OF THE PATTERN  SPURIOUS LOBES IN THE SCANNING ARRAY MAY APPEAR AS A CONSEQUENCE OF THE MISMATCH &URTHER  THERE ARE CONDITIONS WHERE AN ANTENNA THAT IS WELL MATCHED AT BROADSIDE MAY HAVE SOME ANGLE OF SCAN AT WHICH MOST OF THE POWER IS REFLECTED 4HE VARIATION IN ELEMENT IMPEDANCE AND ELEMENT PATTERN IS A MANIFESTATION OF THE  MUTUAL COUPLING BETWEEN RADIATING ELEMENTS THAT ARE IN CLOSE PROXIMITY TO ONE ANOTHER &OR A PRACTICAL DESIGN  TWO EMPIRICAL TECHNIQUES ARE OF GREAT VALUE  7AVEGUIDE SIMULATORS PROVIDE A MEANS FOR DETERMINING THE ELEMENT IMPEDANCE  IN AN INFINITE ARRAY WITH THE USE OF ONLY A FEW ELEMENTS 4HE EFFECTIVENESS OF A  MATCHING STRUCTURE BASED ON THESE MEASUREMENTS MAY ALSO BE DETERMINED IN THE SIMULATOR  ! SMALL ARRAY IS THE BEST TECHNIQUE FOR DETERMINING THE ACTIVE ELEMENT PATTERN 4HE  ACTIVE ELEMENT PATTERN  OBTAINED BY EXCITING ONE ELEMENT AND TERMINATING ITS NEIGH 
 BEAM NOISE JAMMING IS TO MINI 
 FIELD AMPLIFIERS CAN BE PULSED BY MEANS OF A CONTROL ELECTRODE   LOCATED IN THE TUBES DRIFT REGION  WITHOUT A SEPARATE FULL 
 The picture iscertain] ycorrect Hinaqualitative way and this description ofthe electron motion may beused inanexplanation “=~c Hofthe interaction ofthe electrons with the alternating electric fields. “<& HInanoscillating magnetron, theelectrons -Ee pass through ther-ffields shown inFigs. 10.6a FK~,10,12.—Paths ofelec- and 10.6c, and achange intheir velocity re- trons inuniform crossed elec- tricandmagnetic fields.suits. 
 V 4HE !$ CONVERTER OUTPUT SIGNAL IS THEN FREQUENCY SHIFTED BY  COMPLEX MULTIPLICATION WITH THE REFERENCE SIGNAL  EJN 
 This is avoided by placing the input signal on a residual carrier  Cylindrical Spherical  @c+  *3 .$ode -  ovO e - ptrcal  59 9\0v C po""  XIS "i: \oo" Pz  44  screen  Slit  Sqnol- history film  and weighting tronsparancy  Figure 14.6 Optical processor for synthetic aperture radar  OTHER RADAR TOPICS525 LensCathode roytubeIntensitymodified verticalsweep j FiRure14.5Recording ofSARsignalonphotographic filmwiththeaidofaCRT. onatiltedplane,thedifferent phase-front curvatures arecorrected andtheimageiserectedby insertion ofaconicallensplacedatthephase-history filmlocatedinplanePI'Thiserectimage hasitsfocusatinfinity.Theone-dimensional hologram likesignalsrecorded alongthehorizon­ taldimension onthephase-history filmprovidefocusing inthehorizontal plane.Acylin<1rical lensisusedtofocustheimageinthevertical plane. Thefrontfocal-plane ofthecylindrical lens coincides withthatofthephase-history film.(Alenshastheproperty thataFouriertransform relation existsbetween theamplitude distribution oftheillumination atthefrontandback focalplanes.5) Withtheconicalandcylindrical lens.inserted, theimageiserectandissimultaneously focused intherangeandcross-range dimensions, butitliesatinfinity.Tobringtheimageto someconveniently locatedplane,aspherical lensisinserted. 
 A radar designed to discriminate between moving targets and stationary  objects (MTI radar) may introduce additional loss over a radar without this facility. The MTI  discrimination technique results in complete loss of sensitivity for certain values of target  velocity relative to the radar. These are called blind speeds. 
 The symbol l'T0 is spoken. and sometimes  written. as si411w :ero. 
 6 
 Penetration depths were predicted to be 1300 m,  800 m, and 160 m, which turned out to be consistent with ALSE’s performance. MARSIS.  The European Space Agency’s Mars Express  spacecraft includes the  Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument,146 the  first orbital sounder to fly since ALSE. 
 TO 
 OND TO GATHER OVER AN ANGLE OF  n $EPENDING ON THE ANGLE FROM THE AIRCRAFT VELOCITY  VECTOR  A 3!2 MAP OF A FEW FEET RESOLUTION MAY TAKE TENS OF SECONDS TO GATHER AT 8 BAND $"3 AND 3!2 ARE COMPARED IN A QUALITATIVE WAY IN &IGURE  !S THE BEAM IS POSITIONED CLOSER TO THE VELOCITY VECTOR  THE DOPPLER SPREAD IS SMALLER  AND SO COHERENT DWELL TIMES MUST INCREASE FOR THE SAME RESOLUTION 5SUALLY  THERE IS A TRANSITION FROM SHORTER COHERENT PROCESSING INTERVALS #0)S  AND LONGER POST DETECTION INTEGRATIONS 0$)S  TO LONGER #0)S AND SHORTER 0$)S AS THE BEAM APPROACHES THE AIR 
 The problem then becomes one of eval- uating one of the two integrals and substituting the result into Eq. (11.1) to obtain the RCS. If the surface is a good conductor, the total tangential electric field is virtually zero and the total tangential magnetic field is twice the amplitude of the incident tangential magnetic field: nxE = 0 (11.15) J 2n x H, illuminated surfacesnxH = { (11.16) 1 O shaded surfaces Note that the tangential components of both the electric and the magnetic fields are set to zero over those parts of the surface shaded from the incident field by other body surfaces. 
 However, the maximum rate of subsidence is −52 mm/yr, which is lower than the maximum rate of −82 mm/yr by Zhou et al. It is also lower than the rate of −67 mm/yr conducted by Bai et al. and −127 mm/yr conducted by Benattou et al. 
 Analog-to-digital Conversion.  Analog-to-digital conversion involves two stages—   sampling and quantization—each with potential for distorting the received signal.  The received signals must be sampled with sufficient precision and uniformity to  preserve the inherent spectral content across the dynamic range spanned by the sig - nal components—target echoes, clutter, and external noise—after taking account of  the artifacts introduced by quantization and timing jitter, especially in multi-receiver  systems.118,119 Out-of-band Inter-modulation. 
 Transmission Lines and Fittings,  ASESA. 49-28,)  ~1.0 oo ........ OJuTilERADAR EQUATION 57 experience andexperimental observations. 
 Particular arrangement shown gives  135" of phase shift (i wavelength).  of lines and switches required when it is necessary to ininimize the quanti~ation error. The  parallel-line configuration has also been used when phase shifts greater than 2n radians are  needed, as in broadband devices which require true time delays rather than phase shift whictl is  limited to 21c radians. 
 Even with hisfive-minute-old information, the controller can make ashrewd guess astothe target ofsuch anattack, and can marshal defensive fighters accordingly. For many types ofmission however, direct control from theFDP’s isrequired. RepoTting Capabilities ofFDP’s.—Between Oct. 
 There areafew applications inwhich longer-wave radar isequally good, and avery fewwhere long waves aredefinitely preferable, butfortheoverwhelming majority ofradar applications microwave radar isdemonstrably far more desirable than radar operating atlonger wavelengths. The superiority ofmicrowave radar arises largely because ofthe desirability offocusing radar energy into sharp beams, sothat thedirec- tion aswell asthe range oftargets can bedetermined. Inconformity with the well-known laws ofphysical optics, bywhich the sharpness of. 
 AD 117015.  37. Hammer. 
 AES-3, pp. 5-13, January, 1967.  44. 
 BINING INDEPENDENT CLUTTER AND NOISE STATISTICAL MODELS SUCH AS )2) 
 IEEE, vol. 62, pp. 673-680, June 1974. 
 BASED 3!2S TEND TO LOOK TOWARD THE SURFACE AT ANGLES THAT ARE MUCH CLOSER TO VERTICAL THAN DO AIRBORNE 3!2S  4HE MOST COMMONLY USED TERMINOLOGY IS  INCIDENCE THE ANGLE AT T HE ILLUMINATED SURFACE BETWEEN THE LOCAL VERTICAL  AND THE INCOMING ILLUMINATION  4HE ANGLE OF INCIDENCE IS THE COMPLEMENT OF THE GRAZING ANGLE  THE CUSTOMARY  NOMENCLATURE FOR AIRBORNE RADARS )NCIDENCE DIFFERS FROM ELEVATION THE ANGLE AT THE SPACECRAFT BETWEEN VERTICAL AND THE DIRECTION FROM THE SPACECRAFT TO THE SCENE   WHERE THE DIFFERENCE IS DUE TO THE %ARTHS CURVATURE    !LERT 4HE *APANESE 3!2S USUALLY SPECIFY THE LOOK ANGLE AS TH E ELEVATION ANGLE AT THE SPACECRAFT  ALTHOUGH CALLING  THAT ANGLE hINCIDENCEv 4HUS  MOST OF THE LITERATURE CITES  n FOR * 
 This effectively represents one axis ( z) depth and  the orthogonal axis ( x or y) linear position. The amplitude of the signal may be shown  as a series of overlapping signals or, alternatively, a “wiggle plot” (borrowed from  seismic terminology) or a grayscale-coded intensity plot or a pseudo-color image. In  the modeled example shown, the hyperbolic spreading of the target spatial response  can be seen. 
 lJISPLAYS. ANDDUPLEXERS 353 transmission line.rotaryjoint.duplexer. receiver protector. 
 BEAM TRACKING RADARS TO POINT THEIR TYPICALLY NARROW ANTENNA BEAMS IN THE DIRECTION OF THE TARGET 4HIS INFORMATION  CALLED  DESIGNA 
 pp. 864 866, Novctnher, 1974.  85. 
 As the ict(particies, snow, or hail begin to melt, they first become  water-coated ice spheroids. At radar wavelengths, scattering and attenuation by water-coated  ice spheroids the size of wet snowflakes is similar in magnitude to that of spheroidal water  drops of the same size and shape. Even for comparatively thin coatings of water, the composite  particle scatters nearly as well as a similar all-water particle. 
 VELOCITY AIRBORNE RADAR  THE RECEIVED SPECTRUM FROM A STATIONARY  TARGET HAS LINES THAT ARE DOPPLER 
 FERENCE AMONG RADARS THAT OPERATE IN THE SAME FREQUENCY BAND  AS WELL AS IN ATTEMPTING TO MAKE HOSTILE ELECTRONIC COUNTERMEASURES LESS EFFECTIVE 4HE HIGHER THE OPERATING FREQUENCY THE EASIER IT IS TO OBTAIN WIDE SIGNAL AND WIDE TUNABLE BANDWIDTH ! LIMITATION ON THE AVAILABILITY OF BANDWIDTH IN A RADAR IS THE   CONTROL OF THE SPECTRUM  BY GOVERNMENT REGULATING AGENCIES IN  THE 5NITED 3TATES  THE &E DERAL #OMMUNICATION . 
 A power combiner coherently adds together the RF output voltages of individual modules and delivers to a single port the sum total of the modules' output power, minus the losses of the combiner. There are several power combiner-splitter configurations available to the module circuit designer, and all display somewhat varied characteristics.18 In general, the requirements for a power combiner are: 1. The combiner should have low insertion loss, such that transmitter power output and efficiency are not compromised. 
 The Butler network utilizes (N/2) log, N junc-  tions, just as the FFT uses (N/2) logz N computations for an N-point transform.  Within-pulse scanning.'''- lo4 If an antenna beam is scanned sequentially tl~rough its angular  coverage, one position at a time, it illuminates all directions just as does a multiple-beam  array. If the beam is scanned rapidly enough, however, it will have the effect of seeing " almost  simultaneously" in all directions. 
 42°29’N. 71019’\\”. measurements have been made ofthe radar signals received byanair- borne radar system from level, vegetation-co~-cred ground, and ofthe variation with aspect angle ofthe intensity ofthe signals. 
 This effect is shown in Figure 21.17 where the radiation pat - tern is shown at a time several pulse durations after application. The outer perimeter  represents the energy radiated at time zero followed at intervals by the radiation from  the feed points and the end of the element. As it is required to radiate only a very short impulse, it is important to eliminate  the reflection discontinuities from the feed points and ends of the antenna either by  end loading or by reducing the amplitude of the charge and current reaching the ends. 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.616x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 53. R. 
 (13.1 la) is the clutter input, is given by  where rt, is the rnedian value of v and a remains the standard deviation of In A fit  of the log-normal probability density function with a = 6 dB to actual data for sea state 2  to 3 is shown in Fig. 13.5.12 The median value of the theoretical distribution in this case  was equated to the median of the actual data and the a was selected to minimize the maximum  difTerence in dB between the theoretical curve and the actual data.  With niany radars that operate in the presence of sea clutter the Rayleigh pdf generally  uriderestiniates the range of values obtained from real clutter, and the log-normal pdf tends to  overestimate the range of variation. 
   !DAPTIVE 3ENSORS )NCORPORATED  -ARCH   2 ! -ONZINGO AND 4 7 -ILLER   )NTRODUCTION TO !DAPTIVE !RRAYS  .EW 9ORK *OHN 7ILEY   3ONS  . {°£*ÕÃiÊ ««iÀÊ,>`>À  Ê*°Ê-ÌÀ>>Ê 7>Ê°Êi`>À .ORTHROP 'RUMMAN #ORPORATION {°£Ê  , / 
 hoth of which are easier lo obtain al the lower frequencies. Also, a good MTI is easier to  achieve and the effects of weather arc less at these frequencies. The preferred frequency range  for an aircrart-tracking radar is the upper portion of the microwave band (C or X bands) since  it is easier to obtain the wide bandwidths and narrow beamwidths for precision target tracking  than at the lower frequencies. 
 ThefilterintheAGeloopshould passallfrequencies fromdirectcurrenttojustbelow theconical-scan~modulation frequency. TheloopgainoftheAGCfiltermeasured attheconical-scan frequency shouldbelowsothat theerrorsignalwillnotbeaffectedbyAGCaction.(IftheAGeresponds totheconical-scan frequency, theerrorsignalmightbelost.)Thephaseshiftofthisfiltermustbesmallifitsphase characteristic isnottoinfluence theerrorsignal.Aphasechangeoftheerrorsignalisequiva­ lenttoarotationofthereference axesandintroduces crosscoupling, or"crosstalk,"between theelevation andazimuth angle-tracking loops.Crosstalkaffectsthestabilityofthetracking andmightresultinanunwanted nutating motionoftheantenna. [nconventional tracking­ radarapplications thephasechangeintroduced bythefeedback-loop filtershouldbelessthan 10°,andinsomeapplications itshouldbeaslittleas2°.10Forthisreason,afilterwithasharp attenuation characteristic inthevicinityoftheconical-scan frequency mightnotbedesirable becauseoftherelatively largeamountofphaseshiftwhichitwouldintroduce.• Theoutputofthefeedback loopwillbezerounlessthefeedback voltageexceedsa prespecified minimum value~.\Intheblockdiagram thefeedback voltageandthevoltage Yc arecompared inthed-camplifier.Ifthefeedback voltageexceedsVc,theAGCisoperative, whileifitisless,thereisnoAGCaction.Thevoltage 'Vciscalledthedelayvoltage.The terminology maybeabitmisleading sincethedelayisnotintimebutinamplitude. 
 AVERAGED CROSS  SECTION WITH RELATIVELY MODEST FLUCTUATIONS ABOUT A MEAN VALUE !S THE SIZE OF THE RESOLUTION CELL IS REDUCED  CLUTTER INCREASINGLY APPEARS TO CON TAIN SEQUENCES OF ISO 
 OF 
 FECTLY CONDUCTING SPHERE  SHOWN EARLIER IN &IGURE  -ETAL SPHERES ARE USED ROU 
 FICIENT PROVIDE HIGH VALUES OF *#2 4HE PROBLEM OF IMPLEMENTING THE OPTIMUM 
 Therefore, for anisotropic targets, the noise in other angles can be removed from the RCS curve. The easiest way to wipe out the noise is by setting a proper threshold value and eliminating as much noise as possible. The threshold value cannot be set directly. 
 OLUTION REQUIRED  AND THE ANTICIPATED GROUND ATTENUATION AND CLUTTER 4HE DEPTH RANGE OF THE RADAR SYSTEM IS LIKELY TO BE PRIMARILY DEFINED BY THE SOIL  ATTENUATION  ONCE A PARTICU 
 36, no. 2, pp. 7–19, April 1994. 
 Equation (8.9) states that the main beam of the antenna pattern may be positioned to an  angle 8, by the insertion of the proper phase shift Q, at each element of the array. If variable,  rather than fixed, phase shifters are used, the beam may be steered as the relative phase  between elements is changed (Fig. 8.2). 
 CAST EVERY  MINUTES 4O PROVIDE SUFFICIENT BANDWIDTH  TWO SPECIFIC 6(&  +(Z CHANNELS ARE USED  WITH STATIONS ALTERNATING BETWEEN CHANNELS AT EACH MESSAGE 4HERE ARE   MESSAGE SLOTS PER CHANNEL EVERY MINUTE -INUTES ARE ALIGNED TO 5NIVERSAL 4IME #OORDINATED 54#   WHICH IS OBTAINED FROM AN INTEGRAL '.33 RECEIVER 4HE 3/4$-! ALGORITHM EFFECTIVELY RESERVES FUTURE SLOTS FOR STATIONS THAT ARE IN RECEPTION RANGE OF EACH OTHER  PREVENTING MUTUAL INTERFERENCE !)3 FOR 3/,!3 USE IS KNOWN AS  !)3 #LASS ! 4HERE IS A #LASS " SYSTEM THAT IS  DESIGNED FOR NON 
 Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar.  PULSE COMPRESSION RADAR  8.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 For the case of a large time-bandwidth, the magnitude of the autocorrelation function  measured along the relative time delay axis is given by  | ( , )| χ τ τ τu B T 0≈ << |sinc( )|, ||   The x-dB time delay resolution is measured between the values of τ for which   20log | sinc( Bt) |  =  −x (dB)  The range resolution is equal to c/2 times the corresponding time delay resolution  where c is the speed of light. Table 8.1 contains a summary of the resolution widths  for the LFM waveform. 
 AVERAGED MEASUREMENT ACCURACY ON THE ORDER OF CENTIMETERS ALONG TRACKS OF MORE THAN  KM  AND ORBITS THAT RETRACE THEIR SURFACE TRACKS EVERY  TO  DAYS )N CONTRAST  MESOSCALE MISSIONS FOCUS ON SEA 
 DOPPLER SPACE 4HE EVEN DIVISOR 02)S CAN BE PERTURBED ITERATIVELY BY A SMALL AMOUNT TO ACHIEVE THE DESIRED VISIBILITY  4HE NORMALIZED TARGET SIG 
   AND TRANSMITTER 
 IEEE Trans .. vol. GE-15. 
 APPENDIX  Book List  Imex 144  156 |  165  169  I7I  172  . ILLUSTRATIONS  PLATES IN HALF-TONE  PLATE  I. RADAR AND RADIO EQUIPMENT OF MODERN  AIRCRAFT frontispiece  II. 
 Before analyzing  HF skywave radar systems in detail in the sections that follow and describing those  properties of the environment that impact their design and performance, it is instruc - tive to summarize the principle differences between skywave radar and conventional  microwave radar. This provides a cautionary reminder not to extrapolate too readily  from the familiar characteristics of the microwave domain to the HF band. HF skywave radars operate at ranges about an order of magnitude greater than  microwave long-range air surveillance radars. 
 Reliability is a prime concern, as a non - operating radar can force the delay of the ship in port, at great cost to the operator. 22.5 TARGET TRACKING The target tracking function of a shipborne navigation radar has historically been  called an Automatic Radar Plotting Aid (ARPA) . This term is becoming obsolete. 
 First Demonstration of Airborne SAR With Nonlinear FM Chirp Waveforms. IEEE Geosci. Remote Sens. 
 (From GUllnandEast,71 Quart.J.Roy. Meteor.Soc.) rateisshownplottedinFig.13.12.Thedashedlinesareplottedbysumming theRayleigh crosssectionofEq.(13.17)overunitvolumeandsubstituting Eq.(13.21)togive t1=L(Ji=~r4r1.6x\0-12m2/m3 i(13.23) wherefistheradarfrequency inGHzandrtherainfallniteinmm/h.Thesolidcurvesare exactvalueS-computed byHaddock. 71.72TheRayleigh scattering approximation isseentobe satisfactory overmostofthefrequency rangeofinteresttoradar. 
  
 PRESSION IN THE RECEIVER AND EXTRA 
 FIGURE 6.14  Baseband sampling Frequency 0Amplitude 2-B 2B 2-fS 2fS ch06.indd   36 12/17/07   2:03:49 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 2.5, is chosen so as to  achieve a desired false-alarm probability. The false-alarm rate is quite sensitive to the thresh­ old level. For example, a 1 dB change in the threshold can result in three orders of magni­ tude change in the false alarm probability (Fig. 
 LOCATED WITH THE TRANSMITTING SOURCE IS A RECEIVER  WHICH DETECTS THE TRANSMITTED RADAR SIGNAL AND CONTINUALLY ANALYSES ITS FREQUENCY  PULSE LENGTH  AND AMPLITUDE AS THE RADAR ANTENNA ROTATES &ROM THIS INFORMATION  A SIGNAL WAVEFORM IS SYNTHESIZED ON A PULSE 
 6. G. Ruck, D. 
 WIDTH /N THE LEFT IS A POINT TARGET THAT DOES NOT EXCEED THE LIMIT LEVEL ON THE RIGHT IS A POINT TARGET THAT EXCEEDS THE LIMIT LEVEL BY  D" .OTE THAT  FOR THIS EXAMPLE  ) DEGRADES BY  D" FOR THE DUAL CANCELER AND BY  D" FOR THE TRIPLE CANCELER  4HE EXACT RESULT OF THIS CALCULATION DEPENDS ON THE ASSUMED SHAPE OF THE ANTENNA PATTERN FOR THIS EXAMPLE  A  SIN  U U PATTERN TERMINATED AT THE FIRST NULLS WAS ASSUMED  4HERE IS A COMPARABLE IMPROVEMENT FACTOR DEGRADATION DUE TO SPECTRAL SPREADING OF LIMITED  DISTRIBUTED CLUTTER  &IGURES     AND   SHOW THE EXPECTED MEAN  IMPROVEMENT FACTOR FOR TWO 
 ch18.indd   52 12/19/07   5:15:13 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 Interest in millimeter-wave applications stems from the  special properties exhibited by radar at these frequencies, as well as from the challenge of  exploiting a region of the spectrum not widely used. The major attributes of the mlllimeier­ wave region of interest to radar are the large bandwidth, small antenna size, and the character­ istic wavelength. Large bandwidth means that high range-resolution can be achieved. 
 7.26 will be assumed. The  normalantenna pattern is depicted in Fig. 7.26~ as a square beam extending from 8 = 0 to  0 = (I,. 
 4. Van Voorhis, S. N. 
 Inmountainous regions the presentation ofagiven area varies con- siderably with the altitude and position ofthe observing aircraft, and skill isrequired inusing radar pilotage over this sort ofterrain. How- N Frc.339.-Pacific Coast near Balboa, c.Z. Average water-vapor conrcntration over fight path 6.9.g/m~, Wavelength =1,25cm,0.8°beam, altitude 20,000 ft,~adiu~ 23 nauhctil mi. 
 This can play havoc when filtered, amplified, and  transmitted.   Spurious emissions can also interfere with other  RF services  in the deployment area and often  provide a distinctive  signature if they are specific to a particular transmitter  design.   Wide band radars can also “bleed” into surrounding spectrum  causing unintended interference well outside the assigned  spectrum. 
 TION ERRORS &URTHERMORE  2YZHKOV AND :RNIC HAVE SHOWN THAT  +DP 
 Sensors 2019 ,19, 2764 As a measure of image focusing quality we used image contrast, γ, deﬁned as the ratio of standard deviation and mean of image intensity. Typically, a larger contrast means better image quality. The values of contrast in the images in Figure 8wereγa=0.1867,γb=0.1963, andγc=0.2492, respectively; as expected, the image in Figure 8c had the highest contrast. 
 Instead, there is mixing of Kalman Filter  Coordinate  Frame  VariantsCoordinates for  Gain Calculation  (Eqs. 7.32, 7.33)  and state update  (Eq. 7.31)Coordinates for  State Prediction  (Eqs. 
 The  VSWR was better than 2:1 from 100 MHz to 5.8 GHz. There are many configurations of antenna that can be used; crossed dipoles and  parallel dipoles are the most popular. The main reason for the use of two antennas is  that TR switches that are fast enough for GPR are not yet available. 
 P. E. Howland, D. 
 ING DURING A SYNTHETIC APERTURE LENGTH TIME RESULTS IN A CHANGE OF FOCAL LENGTH DIFFERENT COEFFICIENT OF THE QUADRATIC PHASE TERM  OF THE PHASE HISTORY OF THE ILLU 
 SITY  PX    X EXP  
 ................................ ................................ ................................ 
 18 Examples of acquisition  search patterns. (a) Trace of helical  scanning beam; (b) Palmer scan; (c}  spiral scan; (cl) raster, or TV, scan;  (e) nodding scan. The raster scan is  sometimes called an n-bar scan, where  n is the number of horizontal rows. 
 The video signals werethen passed to the waveform generator for mixing with the bright-up waveform, to generate the PPI spokes, before passing to the indicator unit. 3.3.4 Indicator unit type 162 The indicator unit type 162 provided the radar displays and local oscillator controls. Figure 3.6shows the front panel with the PPI and height tube displays, the operator controls and the various connector sockets. 
 Improvement Factor  The IEEE definition of Improvement Factor reads: moving-target-indication (MTI) improvement factor:  The signal-to-clutter power ratio at  the output of the clutter filter divided by the signal-to-clutter power ratio at the input to the  clutter filter, averaged uniformly over all target radial velocities of interest. Synonym: clutter  improvement factor.FIGURE  2.18 Typical densities of point clutter scatterers ( after J.B. Billingsley9  © William Andrew Publishing Inc. 
 Target acquisition involves consideration of the S/N threshold and integration time  needed to accomplish a given probability of detection with a given false-alarm rate  similar to surveillance radar. However, high false-alarm rates, as compared with values  used for surveillance radars, are used because the operator knows that the target is pres - ent, and operator fatigue from false alarms when waiting for a target is not involved.  Optimum false-alarm rates are selected on the basis of performance of electronic cir - cuits that observe each range interval to determine which interval has the target echo. 
 For low-noise-  temperature-ratio diodes, the receiver noise figure is approximately equal to the conversion  < .*,f loss times the IF noise figure.  Balanced mixers. Noise that accompanies the local-oscillator (LO) signal can appear at the IF  frequency because of the nonlinear action of the mixer. 
 -(Z )& FREQUENCY  4HE COHO LOCKING IF A PULSED OSCILLATOR SYSTEM  MUST BE WITHIN  $F      RAD    4HE PULSE TIMING JITTER MUST BE LESS THAN   $T  r r 
 52] TRANSMITTED SPECTRA 129 components present inthe receiver. The modulation isproduced by target motion, and the system makes use ofthis modulation bydeter- mining the presence orabsence ofasignal ofdoppler-shifted frequency, and usually also, bygiving some indication ofthemagnitude and possibly thedoppler shift ofthis signal. 6.2. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 level and then the probability of keeping a number of sidelobes below a given level. By  ignoring the element pattern, the MSSL including failed elements is given by  MSSL =− + + ( )12 2P P PNA aσ σ ηφ  where 1 − P = probability of a failed element. 
 H. Temme, “Phase shifters and time delay elements,” in Advances in Microwaves ,  vol. 4, New York: Academic Press, 1969. 
             . 
 If the random variable is a noise current, the product of the variance  '/a and resistance gives the mean power of the a-c component. The square root of the variance o is  called the stclrldard deviatioit and is the root-mean-square (rms) value of the a-c component.  We shall consider four examples of probability-density functions: the uniform, gaussian,  Rayleigh, and exponential. 
 Another way of assessing these is to model a ﬁxed detection threshold, equivalent to a ﬁxed radar gain setting. The probability of false alarm of clutter- Figure 7.6. Minimum detectable RCS versus range, Pd=0.5,Pfa=10−4, Swerling 1 target;(a) ASV Mk. 
 In this procedure the beam scanning is considered for sliding spotlight mode. Then the interpolation is performed for the whole range line followed by the remodulation process where the ITF is introduced into the range-compressed raw data and ﬁnally after the range decompression the scintillation-contaminated raw data is acquired. By adjusting the beam projection procedure, the ReBP–based SAR–SS can also be applied to simulate the scintillation effect for TOPS and ScanSAR modes, the modiﬁcations of incident and squint angle follow the discussions in this section. 
 Sincethesynthetic-aperture radariscoherent, theimageproduced willhavespeckle; i.e., therewillbeconstructive anddestructive interference whichresultsina..breakup"ofdis­ tributed scatterers. Toreducetheeffectofspeckleandmakeamore"filled-in" image,the samescenecanbeviewedfromdifferent aspectsoratdifferent frequencies, orboth,andthe severalimagessuperimposed. Themultiple lookscanbeobtained asinthesearchlight mode bydwelling withapositionable antenna onthesamearea.Another approach, applicable witha fixedantenna, istonotusethefullsynthetic antenna lengthLetoachievearesolution bee'but tobreakupthesynthetic lengthintomsubsections andlookatthescenefromslightlydifferent aspectseachwitharesolution mbee.Themindependent imagesarethencombined non­ coherently intoasingleimage.Ithasbeensuggested thatthenoncoherent combining of imageso.flesserresolution produces abetterimagewithlessspecklethana~ngleimageof greaterresolution.!!'! 7 IftheSARismapping asceneinwhichtherearemovingobjectssuchascarsortrains,the resulting imagewiltbesmeared inrangeandshiftedinthealong-track dimension duetothe radialmotionoftheobject.Theimagealsowillbedefocused inthealong-track dimension becauseofradialacceleration orcross-range velocityoftheobject.lITheseeffectscancausea distortion anddisplacement ofthemoving-target image.Areduction insignalstrength will alsooccurifthetargetdoppler shiftissufficiently largetobeoutsidethepassband ofthe along-track-dimension processor. 
 Its cure liesnotalone inalteration ofthepulser design, butalso inattention to magnet ron design. 2 The internal impedance ofthepulser plays animportant role inaffect- ingmode stability. There aresignificant clifferences between the opera- tion ofhard-tube and ofline-type pulsers. 
 2015 ,12, 2458–2462. 19. Gong, M.; Su, L.; Jia, M.; Chen, W. 
 Ufimtsev.37,38 (Although  these publications may be difficult to find, we cite them here for completeness. Note  from the editor : The reader interested in this subject might also see the Ufimtsev paper  “Comments on Diffraction Principles and Limitations of RCS Reduction Techniques,”  Proc. IEEE , vol. 
 PERIODIC ANTENNA AND II   
 Lipka, M.: Pulse Compression Filter and Wideband Receiver Evaluation. IEEE 1975 lnternational  Radar Co~(irettce, pp. 283-287, Apr. 
 7. Nortori. W A,: .l'lie ('alculatioti of (;round-wave Field Intensity over a Finitely Conducting Spltericul  Eartli. 
 The relative amplitudes of the two waves and the phase relationship between them can  assume any values. If the amplitudes of the two waves are equal, and if they are 90° out of  (time) phase, the polarization is circular. Circular polarization and linear polarization are  special cases of elliptical polarization. 
 85.Johnson.eM.:LaserRadars, chap.37of"RadarHandbook," M.l.Skolnik (cd.).McGraw-Hill BookCompany. NewYork.1970. 116.Mendez. 
 All of the computations in each  stage are executed before proceeding to the next stage. Also note that the phase shift  in the first stage, W80, is zero, which requires no computation at all.FIGURE 25.41  Radix-2  butterfly+ ++ + + −f FIGURE 25.42  Eight-point, Radix-2 FFT+ W 80++ + + + W 80++ + + −− + W 80++ + + − + W 80++ + + −W 81++ −W 80++ −++ + ++ + W 81++W 80++++ + ++ + W 83++W 82+W 81++W 80+− − − − −−++ + ++ ++ + +++ + ++x(0) x(1) x(2) x(3) x(4) x(5) x(6) x(7)X(0) X(1) X(2) X(3) X(4) X(5) X(6) X(7) STAGE 1 STAGE 2 STAGE 3 ch25.indd   33 12/20/07   1:40:43 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 TED SEQUENTIALLY IN EACH OF THE DESIRED BEAM POSITIONS  ONE TRANSMIT PULSE RIGHT AFTER THE OTHER !FTER ALL THE PULSES HAVE BEEN TRANSMITTED  MULTIPLE SIMULTANEOUS RECEIVE BEAMS ARE FORMED WITH A RECEIVE BEAM LOCATED IN EACH OF THE TRANSMIT BEAM POSITIONS )N THIS METHOD  EACH OF THE TRANSMIT BEAMS HAS THE FULL ARRAY GAIN )N ORDER TO HAVE SIMILAR PER 
 Newton, P. L. Dyson, and J. 
 At vertical incidence there is less backscatter from land than from sea, but tliis is  i~si~ally undesirable since it reduces the range of radar altimeters over land.  Lntld clutter is difficirlt to quantify and classify. The radar eclio from land depends on tlie  type of terrain, as described by its roughness and dielectric properties. 
 PHASE TAPER FROM ELEMENT TO ELEMENT )N THIS MAN 
  6 AND ( n            6 AND ( n     
 F. Thomason: Computer Techniques for Planning and Management of OTH Radars, Naval Res. Lab. 
 AP-35, pp. 1154–1159, October 1987. 14. 
 This switch consists mainly ofarotary joint’ which terminates infour waveguides F.at90°toeach other. These 1SeeFig. 11.13.. 
 True  altitude is the actual airplane distance above mean sea  level.  The altitude can be calculated wi th the values of  distance R and elevation angle ε, as shown in figure 11,  where:    R = aims slant range   ε = measured elevation angle   re = earth's equivalent radius (about 6370 km)     In practice, however, the propagation of electromagnetic waves is  also su bject to refraction, this means, the transmitted beam of the  radar unit isn't a straight side of this triangle but this side is also bent  and it depends on:      the transmitted wavelength,    the barometric pressure,    the air temperature and    the atmospheric hu midity.     Therefore all these equations are an approximation only. 
 This is equivalent to plotting the quantity 4.34a, where the constant  - accourits for tlie conversion from ttie natural logarithm to the base 10 logarithm.  Attenuation by oxygen and water vapor is shown in Fig. 12.9.44,45 Resonance peaks for  water vapor occur at 22.24 GHz (1.35 cm wavelength) and at about 184 GHz, while the  2 4 6 10 20 40 60 100 200  Frequency, GHz  Figure 12.9 Attenuation of electromagnetic energy by atmospheric gases in an atmosphere at 76 cm  pressure. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter.  SEA CLUTTER  15.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 At HF and Millimeter-Wave Frequencies. 
 The assumption ofaperfectly reflecting planeearthappliesinbutafewcases.Alsoassumed wasan omnidirectional antenna patternintheelevation plane.Sinceradarsutilizedirective antennas, theidealized antenna lobestructure asgivenby Eq.(12.4)mustbeappropriately modified to account fortheactualantenna radiation pattern.Theoretically, thenuUsinthelobestructure areatzerofieldstrength sincethedirectandreflected signalsareassumed tobeofequal amplitude. Inpractice, ~henullsare"filledin"andthelobemaxima arereduced becauseof nonperfectreflecting surfaces withreflection coefficients lessthanunity.Thenullswillalsobe filledinifbroadband signalsareradiated bytheradar. Intheaboveexample, thereflection coefficient ofthegroundwastakentobe-1,which appliesforhorizontal polarization andasmoothreflecting surface.Themagnitude andphase ofthereflection coefficients ofvertically polarized energybehavedifferently fromwaveswith horizontal polarization (Fig.12.3aandb).Thecalculated amplitude andphaseofthe reflection coefficient areplottedforasmoothseasurfaceat100and3,000MHz.Itisseenthat thereflection coefficient forvertically polarized energyislessthanthatforhorizontally po­ larizedenergy.Theanglecorresponding totheminimum reflection coefficient iscalledBrew- ster'sangle. 
 HULL FAST FERRIES  THE RADARS NEED TO OPERATE WITH RELATIVE TARGET SPEEDS UP TO  KT /LDER STANDARDS REQUIRED A MINIMUM ANTENNA ROTATION RATE OF  RPM  BUT THIS EXPLICIT REQUIREMENT HAS BEEN OMITTED FROM THE NEW STANDARDS AS OTHER DEPENDENT REQUIREMENTS ARE ADEQUATELY SPECIFIED  SUCH AS THE MAXIMUM RELATIVE SPEED OF TARGETS AND TRACKING ACCURACIES 4HE )-/ PERFOR 
 Incidence differs from elevation (the angle at the spacecraft between vertical and  the direction from the spacecraft to the scene), where the difference is due to the Earth’s curvature. *  Alert! The Japanese SARs usually specify the look angle as the elevation angle at the spacecraft, although calling  that angle “incidence.” Thus, most of the literature cites 35 ° for J-ERS-1’s incidence, which can lead to confusion  if the value of this parameter is important in a given application. The same caveat applies to PALSAR, described  in a subsequent paragraph. 
  
       
 AXIS  AZIMUTH 
 Some indication of the accuracy of this model TABLE 20.4 Specifications of  SECAR, an HF Surface Wave Radar Designed for Surveillance of  the 200 nmi Exclusive Economic Zone Radar SECAR Manufacturer Daronmont Technologies Type Bistatic HF surface wave radar Tx-Rx site separation (km) 50–150 Power (average) (kW) 5  Power (peak) (kW) 5  Frequency band (MHz) 4–16 Waveform linear FM-CW Bandwidth (kHz) 10–50 Waveform repetition frequency (Hz) 4–50 Tx antenna design Single vertical log-periodic antenna with  ground screen Rx antenna design 16 or 32 endfire monopole doublets with  ground screen Rx aperture (m) 200 – 500 Beamwidth    4 MHz                       16 MHz> 9° > 2° No. of simultaneous beams 16 or 32 Instantaneous range depth (km) 100–500 No. of range bins 10–200 Coherent integration time  (CIT) (s) 1–120 No. 
 BASED ENVIRONMENT OFFERS AN ATTRACTIVE ALTERNATIVE REPEAT 
 K-scope.Amodified A-scope inwhichatargetappears asapairofverticaldeflections. Whentheradar antenna iscorrectly pointedatthetarget,thetwodeflections areofequalheight,andwhennotso pointed, thedifference indeflection amplitude isanindication ofthedirection andmagnitude ofthe pointing error. L-scope. 
 ITY  V  IN THE MEDIUM 4HIS IS   NC V     2EFRACTIVITY AND -ODIFIED 2EFRACTIVITY IN THE 4ROPOSPHERE  4HE NORMAL  VALUE OF THE REFRACTIVE INDEX   N  FOR THE ATMOSPHERE NEAR THE %ARTHS SURFACE VARIES  BETWEEN  AND  &OR STUDIES OF PROPAGATION  THE INDEX OF REFRACTION  IS NOT A VERY CONVENIENT NUMBER THEREFORE  A SCALED INDEX OF REFRACTION   .  CALLED  REFRACTIVITY  HAS BEEN DEFINED !T MICROWAVE FREQUENCIES AND BELOW  THE RELATIONSHIP  BETWEEN THE INDEX OF REFRACTION   N  AND REFRACTIVITY   .  FOR AIR THAT CONTAINS WATER VAPOR  IS GIVEN AS   .NP 4E 4S 
  
 20.11, the important features to be noted are as follows: . CLEVATtON POINTING ANGLE (degrees) FIG. 20.10 Resultant relative field strength received in beams A and B resulting from ground reflections as a function of the elevation pointing angle of the beam crossover. 
 MTR-2162, AFAL-77?-73-334, January 1974. 119. Zornig, J. 
 Ttiere is also passive ECM, such as chaff. which reflects radar energy to create clutter and Palsc  targets. The methods employed to combat ECM are called electror~ic co~rr~ter.-co~rirrr~-~~~~~~~strr~c.s. 
 BASED REMOTE SENSING SCATTEROMETERS MEASURE THE NORMALIZED BACKSCATTER WITH  SUFFICIENT PRECISION AND ACCURACY TO DEDUCE THE VALUE OF ONE OR MORE PARAMETERS OF GEOPHYSICAL SIGNIFICANCE &OR EXAMPLE  THE POWER REFLECTED FROM THE OCEAN BACK TO A RADAR IS A FUNCTION OF SURFACE ROUGHNESS AT THE SCALE OF THE RA DARS WAVELENGTH  WHICH   IN TURN  IS A FUNCTION OF THE LOCAL WIND  %STIMATION OF WIND SPEED AND DIRECTION OVER  THE OPEN OCEAN IS THE MOST COMMON APPLICATION FOR THESE INSTRUMENTS ! WIND SCAT 
 Additional isolation canbeobtained byproperly introducing acontrolled sampleofthe transmitted signaldirectlyintothereceiver. Thephaseandamplitude ofthis"buck-off" signal areadjusted tocanceltheportion ofthetransmitter signalthatleaksintothereceiver. An additional 10dBofisolation mightbeobtained.12Thephaseandamplitude oftheleakage signal,however, canvaryastheantenna scans,whichresultsinvarying cancellation. 
 A com- bined power level of greater than 600 W is split eight ways and drives the eight iden- tical output stages. Losses in the output circulator, final power combining, and the fault detection circuitry reduce the combined power level to 2500 W. Output mod- ules are liquid-cooled for normal operation, but an emergency backup forced-air cooling is provided in the event of a primary-cooling-system failure. 
 CLUTTER MOTION ALL CANCELER CONFIGURATIONS   )D"     LOG ; K  
 # FROM A  6 DC POWER SUPPLY 4HE TRANSMIT AMPLIFIER CHAIN CONSISTS OF A PREDRIVER TRANSISTOR FEEDING TWO DRIVER TRANSISTORS  IN TURN FEEDING FOUR FINAL TRANSISTORS  IE  A  
 £x°{  2!$!2 (!.$"//+  &OR A GIVEN SOURCE OF ASYMMETRY SUCH AS THE WIND  VARIOUS PARTS OF THE SPECTRUM  WILL DISPLAY DIFFERENT DIRECTIONAL BEHAVIORS &OR EXAMPLE  IN A FULLY DEVELOPED SEA  THE LARGER WAVES WILL TEND TO MOVE IN THE DIRECTION OF THE WIND WHILE THE SMALLER WAVES WILL BE MORE ISOTROPIC $IRECTIONAL SPECTRA ARE MORE DIFFICULT TO MEASURE AND ARE OBTAINED BY A VARIETY OF EXPERIMENTAL METHODS  SUCH AS AN ARRAY OF WAVE STAFFS TO MEASURE SURFACE HEIGHTS OVER A MATRIX OF POINTS  A MULTIAXIS ACCELEROMETER BUOY  STEREO PHOTOGRAPHY  AND EVEN BY PROCESSING RADAR BACKSCATTER SIGNALS (OWEVER  A FREQUENCY SPECTRUM MEASURED AT A POINT CAN CONTAIN NO KNOWLEDGE OF WAVE DIRECTION  SO A WAVENUMBER SPECTRUM  7+  IS OFTEN DEFINED IN TERMS OF THE FREQUENCY SPECTRUM  3  F    BY THE RELATION   7+    3   F  +  DF D+     WITH THE RELATION BETWEEN   F AND + GIVEN BY %Q  4O ACCOUNT FOR THE WIND DIRECTION   7+  IS SOMETIMES MULTIPLIED BY AN EMPIRICAL FUNCTION OF  + AND DIRECTION  E  RELATIVE  TO THE UP WIND DIRECTION /CEANOGRAPHERS HAVE NOT ALWAYS BEEN IN COMPLETE AGREEMENT ABOUT THE FORM OF  THE FREQUENCY SPECTRUM .ONEQUILIBRIUM WAVE CONDITIONS  INADEQUATE SAMPLING TIMES  POOR GROUND TRUTH  ETC  CAN CONTAMINATE THE DATA SET FROM WHICH EMPIRICAL SPECTRA ARE DERIVED (OWEVER  BY CAREFUL SELECTION OF DATA FROM MANY SOURCES  ENSURING THAT ONLY EQUILIBRIUM FULLY DEVELOPED  SEA CONDITIONS WERE REPRESENTED AND THE WIND WAS ALWAYS MEASURED AT THE SAME REFERENCE HEIGHT USUALLY TAKEN AS  METERS   0IERSON AND -OSKOWITZ  ESTABLISHED A SIMPLE EMPIRICAL SPECTRUM THAT HAS PROVEN POPULAR AND  USEFUL )T HAS THE FORM   3  F      !F   
 Ground-based radomes may utilize roam materi.als, such as polyester polyurethane. of  low dielectric constant and low loss tangent in a relatively thick-wall construction to meet  structural requirements with excellent electrical performance over a wide frequency band. This  is known as a/fwm shell radome. 
 PLER FREQUENCY SHIFT !N ACCURATE MEASUREMENT OF RADIAL VELOCITY REQUIRES TIME (ENCE TIME IS THE BASIC PARAMETER DESCRIBING THE QUALITY OF A RADIAL VELOCITY MEASUREMENT 4HE SPEED OF A MOVING TARGET AND ITS DIRECTION OF TRAVEL CAN BE OBTAINED FROM ITS TRACK  WHICH CAN BE FOUND FROM THE RADAR MEASUREMENTS OF THE TARGET LOCATION OVER A PERIOD OF TIME. £°n  2!$!2 (!.$"//+  !NGULAR $IRECTION  /NE METHOD FOR DETERMINING THE DIRECTION TO A TARGET IS BY  DETERMINING THE ANGLE WHERE THE MAGNITUDE OF THE ECHO SIGNAL FROM A SCANNING ANTENNA  IS MAXIMUM 4HIS USUALLY REQUIRES AN ANTENNA WITH A NARROW BEAMWIDTH A HIGH 
 While the focal distance could be shortened  to comfortably fit axial space limitations (along the boresight of the reflector), it was  then harder to control the field amplitude taper across the reflector due to the proxim - ity of the feedhorn. The solution was to add a smaller subreflector in a subterranean  gallery built especially for it, as suggested in Figure 14.24.63,64 The subreflector had the effect of greatly increasing the focal length of the main  reflector, making it easier to optimize its illumination. This particular configuration  is known as a Gregorian system , characterized by a focus between the two reflectors FIGURE 14.23  A compact range using an offset paraboloidal reflector FIGURE 14.24  Generic dual-reflector compact range configuration20MAIN REFLECTOR PLANE WAVETARGET LOW RCS OGIVAL PYLON SUPPORTFOCUS PRIMARY FEED  ANTENNASUBREFLECTOR (BURIED BELOW GROUND IN SEPARATE SMALL ROOM) ch14.indd   33 12/17/07   2:47:26 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 TRAIN A NEW DIMENSION OF SPACE 
 the computer will nttenipt to correlate them with existing tracks and initiate new tracks, which  car1 tic up the cor~iprrter capacity needlessly. Multiple detections of the same target can occur  iri ;tdjiicent I>eali~ positio~is if the echo sigt~al is of more than ~narginal strength. If the bean1  scarls a utlifort~i pattern. 
 802) (B.W.) Received: 9 October 2018; Accepted: 31 October 2018; Published: 2 November 2018/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: This paper proposes a new interferometric near-ﬁeld 3-D imaging approach based on multi-channel joint sparse reconstruction to solve the problems of conventional methods, i.e., the irrespective correlation of different channels in single-channel independent imaging which may lead to deviated positions of scattering points, and the low accuracy of imaging azimuth angle for real anisotropic targets. Firstly, two full-apertures are divided into several sub-apertures by the same standard; secondly, the joint sparse metric function is constructed based on scattering characteristics of the target in multi-channel status, and the improved Orthogonal Matching Pursuit (OMP) method is used for imaging solving, so as to obtain high-precision 3-D image of each sub-aperture; thirdly, comprehensive sub-aperture processing is performed using all sub-aperture 3-D images to obtain the ﬁnal 3-D images; ﬁnally, validity of the proposed approach is veriﬁed by using simulation electromagnetic data and data measured in the anechoic chamber. Experimental results show that, compared with traditional interferometric ISAR imaging approaches, the algorithm proposed in this paper is able to provide a higher accuracy in scattering center reconstruction, and can effectively maintain relative phase information of channels. 
 There is usually a specially designed weather avoidance radar in the nose of small as  well as large aircraft to warn of dangerous or uncomfortable weather in flight. Another successful remote-sensing radar was the downward-looking spaceborne  altimeter radar that measured worldwide the geoid  (the mean sea level, which is not  the same all over the world), with exceptionally high accuracy. There have been  attempts in the past to use radar for determining soil moisture and for assessing the  status of agriculture crops, but these have not provided sufficient accuracy. 
 p13. 172 176. Marcll, 1970. 
 -- - - .- -  radiation intensity from (lossless) isotropic source with same power input (7.6h)  The power gain should be used in the radar equation since it includes the losses in-  troduced by the antenna. The directive gain, which is always greater than the power gain, is of  importance for coverage, accuracy, or resolution considerations and is more closely related to  the antenna beamwidth. The difference between the two antenna gains is usually small. 
 Alavi, S. Ogut, P. Lymna, and M. 
  (    !(&    (! 
 FICIENT !LTHOUGH THIS EXAMPLE IS FROM MANY YEARS AGO   THE PRINCIPLE IS STILL THE SAME   EVEN THOUGH CURRENT -4) IMPROVEMENT FACTORS ARE BETTER BY TENS OF D"S 2ESTRICTION OF THE )& DYNAMIC RANGE IS STILL A VERY EFFICIENT WAY OF NORMALIZING CLUTTER RESIDUE DUE  TO SYSTEM INSTABILITIES OR CLUTTER SPECTRAL SPREAD TO SYSTEM NOISE 4HIS IS TRUE WHETHER  OR NOT THE RADAR USES PULSE COMPRESSION 0RIOR TO THE DEVELOPMENT OF MODERN CLUTTER MAPS FOR CONTROLLING FALSE ALARMS  CAUSED BY CLUTTER RESIDUE  OR THE MORE RECENT SUGGESTION THAT BINARY INTEGRATION CAN MITIGATE IMPULSE 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 11.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 from high bus voltages (25–75 volts), while maintaining transistor-like properties at  higher operating temperatures than Si or GaAs.22 They are finding application in the  S band, C band, or X band frequency ranges. 
 mental information about the interaction between rain and wind-driven sea scat- ter. Laboratory measurements by Moore et al.56 with artificial "rain" suggested that for light winds the backscatter level increased with the rain rate, while for heavy winds rain made little difference. In measurements in natural rain over Chesapeake Bay, Hansen57 found that even a light rain (2 mm/h) changes the spectral character of sea clutter at moderate wind speeds (6 m/s) by introducing a significant high-frequency component. 
 Scatter depends on dielectric constant, which depends on moisture content.Thus scatter from wet soils at angles off vertical is usually much higher . CHAPTER 13 SEA CLUTTER Lewis B. Wetzel Naval Research Laboratory 13.1 INTRODUCTION For an operational radar, backscatter of the transmitted signal by elements of the sea surface often places severe limits on the detectability of returns from ships, aircraft and missiles, navigation buoys, and other targets sharing the radar reso- lution cell with the sea. 
 Radar sets have greater range capabilities while functioning withthe longer pulse length because a greater amount of energy is transmitted ineach pulse. While maximum detection range capability is sacriﬁced when using the shorterpulselength,betterrangeaccuracyandrangeresolutionareobtained.With the shorter pulse, better deﬁnition of the target on the radar-scope isobtained; therefore, range accuracy is better. RANGE RESOLUTION is ameasure of the capability of a radar set to detect the separation betweenthose targets on the same bearing but having small differences in range. 
 2.21. The aspect is at grazing incidence. When averages of the cross section are taken  about the port and starboard bow and quarter aspects of a number of ships (omitting the peak  at broadside), a simple empirical expression is obtained for the median (50th percentile) value  of the cross section:  a = 52f i /'1. 
 on Acoustics, Speech and Signal Processing ,   vol. ASSP-23, no. 2, pp. 
 MENTS  NOT EVEN THE UNITS IN WHICH THE 2#3 DATA ARE DISPLAYED (OWEVER  EVEN IF WE DO NOT KNOW THE TEST FREQUENCY OR POLARIZATION  WE DO KNOW THAT THE FULL 
 2 WAS LAUNCHED IN  4HE  LAUNCH OF A SEQUEL FAILED %23 
 177. Inoue et al., “Season-long daily measurements of multifrequency (Ka, Ku, X, C, and L) and full- polarization backscatter signatures over paddy rice field and their relationship with biological  variables,”  Remote Sensing of Envir. , vol. 
 TIONS OF THE SLOW 
 VIDE PHASED ARRAY PERFORMANCE IN AN AIRBORNE PLATFORM 4HE -ULTI 
 The experimental demonstration that, on occasion, the environment supports   ~80 dB sub-clutter visibility obliges the radar designer to ensure that the receiving  system and signal processing operations do not unwittingly degrade the radar perfor - mance. Some appropriate design considerations are • An analog-to-digital (A/D) converter of at least 16-bit precision is in order for HF  radars with high power-gain products, PavGT GR. • Receiving apertures, waveform bandwidths, and coherent integration times should  provide enough samples and high enough sampling rates to resolve unambiguously  distinct features of the clutter spectrum where such resolution impacts on target  detectability or the extraction of important information. 
 214-218, March, 1973.  32. Millett, R. 
 However, thereareotherinstances inwhichthetarget's position in{threedimensions mustbeknown.Inthissection,radarmethods forObtaining the elevation angleorheightofatargetwillbediscussed briefly.Theheightofatargetabove thesurfaceoftheearthmaybederived fromthemeasurement ofelevation angleandrange. Theuseofheightasthethirdtarget-coordinate ismoredesirable thantheelevation anglein applications wheretheheightisapttobeconstant. Thisisusuallytrueforcommercial aircraft andforsatellites withnearlycircular orbits.Aradarwhosepurpose isthemeasurement of elevation angle,andwhichusuallydoesnotmeasure theazimuth angle,iscalledaheight-finder radar.Aradarwhichmeasures theelevation anglealongwiththeazimuth angle(andrange)is calleda3Dradar.Onewhichmeasures therangeandoneanglecoordinate (usually azimuth) iscalleda 2Dradar. 
 The difference frequency isapplied toafrequencY-dis- criminator circuit whose crossover issetatthe intermediate frequency. rhe variation ofthe height ofdiscriminator output pulses asafunction aflocal-oscillator frequency isshown inFig. 12.11. 
 SYNCHRONOUS DAWN 
 10.2). A matched filter is one designed to maximize the output peak signal to average  noise (power) ratio. It has a frequency-response function which is proportional to the complex  conjugate of the signal spectrum. 
 T 3fo T2  When terrns greater tliari the first two can be neglected (which applies when 2rtBZt3 @ 3fo T2),  Eq. ( 1 1.56) reduces to the classical linear FM waveform. Thus the linear FM, or chirp, pulse-  con1pression waveform is a pract icol approximation to the theoretical doppler-toleran t  wavefornl. 
 ELEMENT ARRAY !MPLITUDE 1UANTIZATION  7HEN THE APERTURE OF A PHASED ARRAY IS DIVIDED INTO  EQUAL SUBARRAYS  THEN THE AMPLITUDE DISTRIBUTION ACROSS EACH SUBARRAY IS CONSTANT !PERTURE TAPER FOR THE ANTENNA IS APPROXIMATED BY CHANGING THE AMPLITUDE FROM SUBAR 
 This allows the diode to act as a switch. Phase shifters based on diode devices can be  of relatively high power and low loss, and can be switched rapidly from one phase state to  another. They are relatively insensitive to changes in temperature. 
 TION v )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS   VOL   NO   PP n   *ULY   $ ( -OONEY  h0OST $ETECTION 34# IN A -EDIUM 02& 0ULSE $OPPLER 2ADAR v 53 0ATENT      *UNE     & % .ATHANSON   2ADAR $ESIGN 0RINCIPLES   ND %D .EW 9ORK -C'RAW 
 DOPPLER CELL ! $"3  MAP MAY TAKE A SEC 
 CHAPTER 7 THE EMPLOYMENT OF RADAR DATA BYB.V.BOWDEN, L.J.HAWORTH, L.N.RIDENOUR, AND C.L.ZIMMERMAN* 7“1. The Signal and ItsUse.—The presentation ofecho signals onan indicator bynomeans completes theproblem ofdesigning anoperation- ally useful radar system. Itisnecessary that action ofsome sort be taken onthebasis oftheinformation afforded bytheradar. 
 Tuley, J. M Ralston, F. S. 
 Lo, S. W. Lee; Chapman & Hall; ISBN 0 -442- 01592- 5, ISBN 0- 442-01593- 3, ISBN 0- 442-01594- 1  − Rothammels Antennenbuch, DARC  Verlag Baunatal, ISBN 3 -88692- 033-X . 
 4.  Academic Press, New York, 1969.  31. 
 Sub-clutter visibility is potentially obtainable from coherent CMRs, which have  been made affordable by the continued reduction in cost of microwave power semicon - ductors (for instance, using Gallium Nitride technology), precision digitally controlled  signal generators, and fast digital signal processors. Coherent CMRs are discussed  under “Solid-state CMR” in Section 22.4. Vertical Lobing. 
 The  variation in magnetron efficiency is similar to that of the variation with power.  The change in the oscillator frequency produced by a change in the anode current for a  fixed load is called the pushingfigure. A plot of frequency vs. 
 The first detection of aircraft using the wave-interference effect was made in June, 1930, by  L. A. Hyland of the Naval Research Laboratory.1 It was made accidentally while he was  working with a direction-finding apparatus located in an aircraft on the ground. 
 Transmitter = r- -  Mixer - 3d harmonic  filter - Mixer  L - Low -pass  filter  L Doppler - frequency  90INTRODUCTION TORADAR SYSTEMS 0.8 0.7 0.6 0.5J3(Dl 04 CJ0.3 -s: 0.2 0.1 012D -0.1 -0.2 -0.3 -0.4Figure3.16PlotofBessel function~ oforder0,1,2,and3;D= (N/fm)sin2nfmRolc. Thetechnique ofusinghigher-order Besselfunctions hasbeenapplied tothetypeof doppler-navigation radardiscussed inthenextsection.Ablockdiagram ofaCWradarlIsing thethirdharmonic (J3term)isshowninFig.3.17.Thetransmitter issinusoidally frequency­ modulated atafrequency 1mtogenerate thewaveform givenbyEq.(3.15).Thedoppler-shifted echoisheterodyned withthetransmitted signaltoproduce thebeat-frequency signalof Eq.(3.16).Oneoftheharmonics offmisselected (inthiscasethethird)byafiltercentered at theharmonic. Thefilterbandwidth iswideenoughtopassbothdoppler-frequency sidebands. 
 B., J. A. Buisson, and D. 
 OUT AS A FUNCTION OF RANGE WILL INCREASE PROPORTIONALLY  TO THE NUMBER OF SWEEPS 5LTIMATELY THIS RUN 
 75, pp. 551 563, Jan. 20. 
 4. Steinberg, B. D.: "Principles of Aperture and Array System Design—Including Ran- dom and Adaptive Arrays," John Wiley & Sons, New York, 1976. 
 TO 
 Wu, R. K. Moore, R. 
 621, 1925.  33. Espenshied. 
 I%l;ickwcll. and T. A: Wilmot: Rird Strike and [tie Radar Properties of Birds,  Iitr111rrot1~1 'o. 
 The MTD processor employs  several techniques for the increased detection of moving targets in clutter. Its implementation  is based on the application of digital tech~iology. It utilizes a three-pulse canceler followed by  an 8-pulse FFT doppler filter-bank with weighting in the frequency domain to reduce the filter  sidelobes, alternate prfs to eliminate blind speeds, adaptive thresholds, and a clutter map that  is used in detecting crossing targets with zero radial velocity. 
 J. Sachs, P. Peyerl, F. 
 Similar logic can be  applied to saturated range gates to determine if the largest signal in the filter bank is  in the passband or represents saturated clutter returns. Saturated returns with the peak  signal in the doppler passband can represent valid targets at short ranges and need not  be subjected to the sidelobe blanking logic. The most stressing dynamic-range requirement is due to main-beam clutter when  searching for a small, low-flying targets. 
 A valid target is then tracked in frequency, and guidance commands are extracted from it. The front antenna conically scans the received beam. The resulting amplitude modulation of the received signal is recovered in the speedgate and resolved into the two orthogonal pitch and yaw gimbal axes. 
 61–85, 1978. 103. B. 
 It is also possible to scan  the beam with electronic phase shifters. With a scanning phased-array antenna, however, the  radiation pattern, which is a fan beam at broadside, becomes a conical beam when scanned off  broadside. This can cause an error in the elevation measurement if the target is off the center o  the beam. 
 Cross, D. C., and J. E. 
 A single pencil beam is rotated in  azimuth with its elevation angle increased one beamwidth per revolution so as to trace a  helical pattern. It is a simple technique, but is not or high accuracy since it is difficult to  interpolate between adjacent elevation beam positions.  Within-pulse scanning.40·41 In the frequency-scan 3D radar discussed above, a single pencil  beam is step-scanned in elevation. 
 VECTOR CAN BE USED TO REMOVE THE AMBIGUITY Ç°{Ê 
 &- RANGING FROM A TARGET AT THE MAXIMUM INSTRUMENTED RANGE &OR DOPPLER 
    ¯             F .# . FDF #! ' F .¯     
 ING SPHERICALLY FROM A LOW GAIN  BROAD 
 Sensors 2018 ,18, 2929. [ CrossRef ][PubMed ] 6. Dong, J.-M.; Li, Y.-Q.; Deng, B. 
 Open circles are the maximum  values averaged over 10° intervals: solid circles are median values. Radar is assumed to be in the same  plane as the aircraft.64  It can be seen that the radar cross section of an aircraft is difficult to specify concisely.  Slight changes in viewing aspect or frequency result in large fluctuations in cross section. 
 L. B. Walker, High Power GaAs FET Amplifiers , Norwood, MA: Artech House, 1993, p. 
 ,-Ón 4HE CROSSED 
 Middleton: A Theoretical Comparison of Visual, Aural, and Meter Reception  of Pulsed Signals in the Presence of Noise, J. Appl. Phys., vol. 
 SCALE RANGE  OF THE !$ CONVERTER RELATIVE TO THE RMS INTERFERENCE LEVEL )T IS SET TO ACHIEVE A    SUFFICIENTLY HIGH PROBABILITY THAT FULL 
 .$circular groo~-e, likF\\-ise aqufirtcr wavelength deep, forms the short-circuited terminating section. .irLlb- bergasket intheouter groove serves tokeep thewavegyide airtight. By careful choice ofdimensions, such ajoint canbemade tobeagood match over afrequency band 12to15per cent wide. 
 1973,London, IEEConference Publication no.105,pp.207-212. 35.Odoardi, F.,andC'.Maggi:Modern RadarDataDisplaySystem:TheSeleniaIDM-7DigitalDisplay, RiristaTecnica Selenia(Rome.Italy),vol.2,no.4,pp.53-61,1975. 36.Kernan. 
  &)'52%  #RAMER 
 22. Perkins, W. B.: personal communication, January 1988. 
 This work was followed by Naval Research Laboratory (NRL) reports13 and a book14 in which further details were pre- sented. Contributions to the subject of range prediction have also been made by many others, far too numerous to mention by name. Only the major contributions can be recognized in this brief history. 
 27, pp. 36–39, July 1990.  8. 
 tllcy  tcrid to cxliitit a slow hirt predictable deterioratio~i with respect to iritertial leakage as a result  of r~lccliariical wear.  llotli electric arid Iiydrarrlic clrives are used i~i surveillance radars. Surveillatice anten~las  opcrntc at co~istarit rotation rate. 
 E'  Colhode roy lube Intensity modified  vertical sweep  J  /  /  Lens  Reel OTHER RADAR TOPICS 525  ~ Recorded  signals  Fiaure 14.5 Recording of SAR signal on photographic film with the aid of a CRT.  on a tilted plane, the different phase-front curvatures are corrected and the image is erected by  insertion of a conical lens placed at the phase-history film located in plane P 1• This erect image  has its focus at infinity. The one-dimensional hologramlike signals recorded along the horizon­ tal dimension on the phase-history film provide focusing in the horizontal plane. 
 Walton, Jr. (ed.): Radome Engineering Handbook , New York: Marcel Dekker, 1970. 55. 
  ES   O   THE DIFFRACTION COEFFICIENT  8 IN %Q   BECOMES SINGULAR  A MEANINGLESS RESULT 7HEN THE SCATTERING DIRECTION  ES IS ALIGNED  ALONG THE SPECULAR DIRECTION WHERE THE LOCAL ANGLE OF REFLECTION IS EQUAL TO THE LOCAL ANGLE OF INCIDENCE  THEN  E I   ES   O  )N THIS CASE  IT IS THE DIFFRACTION COEFFICIENT  9 IN  %Q  THAT BECOMES SINGULAR  A SIMILARLY MEANINGLESS RESULT .OTE THAT THESE TWO SINGULARITIES DO NOT DEPEND ON  BODY GEOMETRY  BUT ONLY ON THE R ELATIVE DISPOSITIONS OF  THE INCIDENCE AND SCATTERING DIRECTIONS 0HYSICAL 4HEORY OF $IFFRACTION  4HE SINGULARITIES IN '4$ ARE OVERCOME IN THE  PHYSICAL THEORY OF DIFFRACTION  04$  FORMULATED BY 0 )A 5FIMTSEV   !LTHOUGH  THESE PUBLICATIONS MAY BE DIFFICULT TO FIND  WE CITE THEM HERE FOR COMPLETENESS  .OTE  FROM THE EDITOR 4HE READER INTERESTED IN THIS SUBJECT MIGHT ALSO SEE THE 5FIMTSEV PAPER  h#OMMENTS ON $IFFRACTION 0RINCIPLES AND ,IMITATIONS OF 2#3 2EDUCTION 4ECHNIQUES v 0ROC )%%%  VOL   PP n  $ECEMBER   ,IKE +ELLER  5FIMTSEV RELIED ON THE APPROXIMATE WIDE 
 SIGHT VELOCITY   6TLOS  IS OBSERV 
 The analysis of anisotropic irregularity is performed by C. Wang [ 23] and a statistical evaluation of L-band equatorial scintillation is carried out by Meyer [ 24]. The SAR scintillation simulator (SAR-SS) is studied by Carrano [ 27] based on the phase screen theory for predicting the scintillation effect on the L-band SAR. 
 The only design considerations arising from the nature ofthe pulser load arethose governing ripple and regulation. In general, the a-csupply frequency will beless than the pulse rate, and smoothing condensers capable ofholding thevoltage essentially constant . -s7 FIG. 
 Thegreaterthetransmitter frequency deviation inagiventimeinterval. themoreaccurate the measurement ofthetransittimeandthegreaterwillbethetransmitted spectrum.. 82 1NTRODUCTION TO RADAR SYSTEMS  Range and doppler measurement. 
 Solar storms (sunspots and flares) can increase the  solar-noise level several orders of magnitude over that of the "quiet," or undisturbed sun.  The solar noise can sometimes be of significant magnitude to affect the sensitivity of low-noise  radar receivers from energy received in the antenna sidelobes. The sun also can be used  as a source to calibrate the beam-pointing (boresight) of large  antenna^.'^ Discrete radio  sources, call& radio stars, are too weak at radar frequencies to be a serious source of interfer-  ence, but they have been used in conjunction with sensitive receivers to determine pointing and  focusing corrections for large antennas.59  System noise temperature. 
 RIES   0HYSICAL /PTICS 0/   OR INDUCED CURRENT METHODS    'EOMETRICAL /PTICS '/  METHODS  WITH AND WITHOUT DIFFRACTION TERMS  AND   RIGOROUS  OR FULL 
 FREQUENCY RADARS  AND FROM PULSE TO PULSE WITH FREQUENCY 
 MON  4HIS VALUE TRANSLATES INTO A NOISE SPECTRAL DENSITY OF n D"7(Z 3IMILAR  MEASUREMENTS HAVE BEEN MADE AT 5(&  WITH n D" NOISE FIGURES BEING OBTAINED USING SPECTRAL CANCELLATION BY A LEAST 
 Kraus. J. D.: "Antennas." McGraw-Hill Book Co., New York, 1950. 
 Therefore, the tracking bandwidth  should be narrow to reduce the effects of noise or jitter, reject unwanted spectral components  such as the conical-scan frequency or engine modulation, and to provide a smoothed output of  the measurement. On the other hand, a wide tracking bandwidth is required to accurately  follow, with minimum lag, rapid changes in the target trajectory or in the vehicle  carrying the radar antenna. That is, a wide bandwidth is required for following changes in the  target trajectory and a narrow bandwidth for sensitivity. 
 Inone specific case, a3-phase power supply furnishing 3-kw direct current showed asaving ofalmost 70lbover the equivalent single-phase unit.. 560 PRIME POWER SUPPLIES FORRADAR [SEC. 14.3 Inmany cases, alimit onthe number ofengine mounting pads will force the use ofadual-purpose generator such asthe Bendix Aviation Corporation NEA-7, which delivers 125 amp of27.5-volt direct current and also, independently controlled involtage, 2500 vaofsingle-phase, 115-volt alternating current at800 to1600 cpsforshaft speeds of4000 to8000 rpm. 
 46 HOW RADAR WORKS  time-base line will be formed in such a time interval  that the homecoming echo can be seen. Then the whole  thing switches off until the next pulse goes out, perhaps  siz second later. Transmitter and receiver have thus to  work in unison, and for practical purposes it does not  matter much if we cause the transmitter to ‘trigger off’  the receiver, or if it happens the other way round. 
 It  might consist of an air-core inductance with taps along its length to which are attached  capacitance to ground. A transformer is used to match the impedance of the delay line to that  of the load. A perfect match is not always possible because of the nonlinear impeJanct!  characteristic of microwave tubes. 
 MOTION CLUTTER POWER SPECTRUM THAT IS WEIGHTED BY THE ANTENNAS TWO 
 The advantage of this technique is that it  allows the effective IF signal bandwidth to be substantially reduced, allowing digitiza - tion and subsequent digital signal processing, at more readily achievable sample rates.  By applying a suitably matched chirp waveform to the receiver first LO, coincident  with the expected time of arrival of the radar return, the resultant IF waveform has  a significantly reduced bandwidth for targets over a limited range-window of inter - est. Provided that the limited-range window can be tolerated, a substantially reduced  processing bandwidth allows more economical A/D conversion and subsequent digital  signal processing. 
 ETERS ASSOCIATED WITH A CLUTTER POINT ARE REFERRED TO BY THIS CLUTTER NUMBER !GAIN  EACH CLUTTER NUMBER IS ASSIGNED TO A SECTOR IN AZIMUTH FOR EFFICIENT ASSOCIATION 2ADAR $ETECTION !CCEPTANCE  7HEN THE RADAR SYSTEM HAS EITHER NO OR LIMITED  COHERENT PROCESSING  NOT ALL THE DETECTIONS DECLARED BY THE AUTOMATIC DETECTOR ARE USED IN THE TRACKING PROCESS 2ATHER  MANY OF THE DETECTIONS CONTACTS  ARE FILTERED OUT IN SOFTWARE USING A PROCESS CALLED  ACTIVITY CONTROL   4HE BASIC IDEA IS TO USE DETECTION  SIGNAL CHARACTERISTICS IN CONNECTION WITH A MAP OF THE DETECTION ACTIVITY TO REDUCE THE RATE OF DETECTIONS TO ONE THAT  IS ACCEPTABLE FOR FORMING TRACKS 4HE MAP IS CONSTRUCTED  BY COUNTING THE UNASSOCIATED DETECTIONS THOSE THAT DO NOT ASSOCIATE WITH EXISTING TRACKS  AT THE POINT IN THE TRACK PROCESSING SHOWN IN &IGURE  #OUNTS ARE AVERAGED OVER MANY REVISITS OF THE RADAR TO ACHIEVE  STATISTICAL SIGNIFI 
 FORMING NETWORK 0&.  AS THE  ENERGY STORAGE ELEMENT ! SWITCH INITIATES THE DISCHARGE OF THE ENERGY STORED IN THE 0&. 4HE SHAPE AND DURATION OF THE PULSE ARE DETERMINED BY THE PASSIVE ELEMENTS OF THE 0&. 4HE SWITCH HAS NO CONTROL OVER THE PULSE SHAPE  OTHER THAN TO INITIATE IT 4HE PULSE ENDS WHEN THE 0&. HAS DISCHARGED SUFFICIENTLY ! DISADVANTAGE OF THIS ACTION IS THAT THE TRAILING EDGE OF THE PULSE IS USUALLY NOT SHARP SINCE IT DEPENDS ON THE DISCHARGE CHARACTERISTICS OF THE 0&. )T HAS BEEN WIDELY USED IN THE PAST FOR MAGNETRON PULSING. £ä°Ó{  2!$!2 (!.$"//+  )N AN ACTIVE 
 There is also the  valuable technique of radar trainers and synthetic  apparatus developed by G. W. A. 
 This  describes the ability of an MTI radar to detect moving targets which occur in the relatively  clear resolution cells between patches of strong clutter. Clutter echo power is not uniform, so  if a radar has sufficient resolution it can see targets in the clear areas between clutter patches.  The higher the radar resolution, the better the interclutter visibility. 
 15.4 Bipolar video: single sweep.ANTENNA DUPLEXERSIGNALDOWNCONVERTERLINEAR-LIMITINGIF AMPLIFIERPHASEDETECTORBIPOLARVIDEO10-BITA/DCONVERTER DIRECTIONALCOUPLER STALO(133OMHz MAGNETRONTRANSMITTER(1300MHz)LOCK-PULSEDOWNCONVERTERPULSE-LOCKAMPLIFIERCOHO(30MHz) GATE 10-BITBIPOLARDIGITALWORDS (1MHz RATE)PRIMEMORY2500 10-BITWORDSSUBTRACTORBIPOLARDIGITALWORDS ABS.VALUED/ADETECTORVIDEOLIMITERUNIPOLARDIGITALWORDSANALOG MTIVIDEO TODISPLAYS DIGITAL MTI OUTPUTTOAUTOMATIC DETECTIONSYSTEM REGION OF STRONGCLUTTER RETURNPOINTTARGET RANGE SYSTEMNOISEAMPLITUDE . FIG. 15.5 Bipolar video: several sweeps. 
  
 2. Antenna gain constant over its beamwidth and zero elsewhere 3. Range variation across the small illuminated area negligible = /V^ r G^dA = /^V0Go2VK)A/,/ (12 21) " (4TT)3^ /?4 2V/?2 and so o = Pr 2vR2 07 />, X4G02VK)A/, (12-22) Doppler scatterometers need not use fore-and-aft beams. 
 These phenomena occur during extreme cases of super-refraction. Energy radiated at angles of 1˚ or less may be trapped in a layer of the atmospherecalled a SURFACE RADIO DUCT. In the surface radio duct illustrated inﬁgure 1.10, the radar rays are refracted downward to the surface of the sea,reﬂected upward, refracted downward again within the duct, and so oncontinuously. 
 ITY FOR GROUND TARGETS IS VERY STRONGLY INFLUENCED BY MOISTURE CONTENT SINCE THE RELATIVE PERMITTIVITY OF LIQUID WATER IS FROM ABOUT  AT 8 BAND TO ABOUT  AT 3 BAND AND LONGER WAVELENGTHS  WHEREAS MOST DRY SOLIDS HAVE PERMITTIVITIES LESS THAN  !TTENUATION IS ALSO STRONGLY INFLUENCED BY MOISTURE SINCE WET MATERIALS USUALLY HAVE HIGHER CONDUCTIVITY THAN THE SAME MATERIALS DRY &IGURES  AND  SHOW THE EFFECT OF MOISTURE CONTENT ON PROPERTIES OF PLANTS AND OF SOIL 4HE HIGH PERMITTIVITY OF PLANTS WITH MUCH MOISTURE MEANS THAT RADAR RETURN FROM CROPS VARIES AS THE PLANTS MATURE  EVEN WHEN GROWTH IS NEGLECTED &)'52%     -EASURED  MOISTURE  DEPENDENCE  OF  THE  DIELECTRIC   CONSTANT OF CORN LEAVES AT     AND  '(Z  3 IS THE SALINITY OF WATER  CONTENT IN PARTS PER THOUSAND   DV   DV   JDVp IS THE COMPLEX DIELECTRIC  CONSTANT IN &M  AND MV IS THE VOLUMETRIC MOISTURE CONTENT IN KGM  AFTER & 4 5LABY  2 + -OORE  AND ! + &UNG  . 
 This paper describes the ground-based X-band MIMO radar SPARX recently developed by IDS GeoRadar in order to overcome the limits of IDS GeoRadar’s well-established ground based interferometric SAR systems. The SPARX array consists of 16 transmit and 16 receive antennas, organized in independent sub-modules and geometrically arranged in order to synthesize an equally spaced virtual array of 256 elements. Keywords: GB-SAR; MIMO radar; radar imaging 1. 
 WAVE METHODS INCLUDE   FOR EXAMPLE  THE METHOD OF MOMENTS -/-   THE FINITE ELEMENT METHOD &%-   AND THE FINITE DIFFERENCE TIME DOMAIN &$4$  METHOD !LTHOUGH THESE METHODS ARE VERY RIGOROUS AND HIGHLY ACCURATE  THEY ARE NOT GENERALLY EMPLOYED FOR REFLECTOR DESIGN ANALYSIS BECAUSE THEY TEND TO BE TOO COMPUTATIONALLY INTENSIVE 4HESE METHODS ARE  MORE TYPICALLY APPLIED FOR PRECISION ANALYSIS OF MICROWAVE DEVICES OR ELECTRICALLY hSMALLERv ANTENNAS  EG  RADIATORS AND FEEDS  THAT ARE NO MORE THAN A FEW WAVELENGTHS IN SIZE )N RECENT YEARS  HYBRID METHODS INCORPORATING 0/ OR '/'4$ ALONG WITH -/-  &%-  OR &$4$ HAVE BEEN  DEVELOPED 4HESE METHODS ENABLE ENHANCED REFLEC 
 The digital signal processing function is not normally considered to be part of  the receiver. 6.2 NOISE AND DYNAMIC-RANGE  CONSIDERATIONS Receivers generate internal noise that masks weak signals being received from the radar  transmissions. This noise contribution, which can be expressed as either a noise tem - perature or a noise figure, is one of the fundamental limitations on the radar range. 
 Historically, attempts to provide a theoretical explanation of the observed behav - ior of clutter signals trace essentially from the work pursued during World War II  and described in the well-known MIT Radiation Laboratory book mentioned above.1  Unfortunately, the scattering models developed during this period, along with most  of those published over the following decade, failed to account in any convincing  way for the behavior of sea backscatter. In 1956, however, Crombie observed that at  high-frequency (HF) wavelengths (tens of meters) scattering appeared to arise from  a resonant interaction with sea waves of one-half of the incident wavelength, i.e., to  be of the Bragg type.5 Reinforced by the theoretical implications of various small  waveheight approximations and wave-tank measurements under idealized condi - tions, the Bragg model  was introduced into the microwave regime by many workers  in the mid-1960s.6–8 This produced a revolution in thinking about the origins of  sea clutter because it involved the sea wave spectrum , thus forging a link between  clutter physics and oceanography in what became the field of radio oceanography .  However, fundamental conceptual problems in applying the Bragg hypothesis in  microwave scattering, along with its inability to address significant aspects of mea - sured sea clutter, have led through the years to continuing inquiry into the physical  origins of sea scatter and how best to model it.9–14 This being the case, speculation  about physical models will be kept to a minimum in the sections on the empirical  behavior of sea clutter. 
 NMI RANGE INTERVAL AT THE RANGE WHERE THE TARGET IS EXPECTED  POSSIBLY FROM COARSE RANGE DESIGNATION FROM SEARCH RADAR 2ANGE 4RACKING  /NCE A TARGET IS ACQUIRED IN RANGE  IT IS DESIRABLE TO FOLLOW THE  TARGET IN THE RANGE COORDINATE TO PROVIDE DISTANCE INFORMATION OR SLANT RANGE TO THE TAR 
 Equation 8.3 applies to isotropic radiating elements, but practical antenna elements that are  designed to maximize the radiation at 0 = 0°, generally have negligible radiation in the direc-  tiori 0 = _+ 90". Thus the effect of a realistic elernent pattern is to suppress the grating lobes at  +YO'. It is for tliis reason that an element spacing equal co one wavelength can be tolerated for  a tionqcanning array. 
 44, pp.  801-810, June, 1956.  34. 
 It is also possible at HF  to propagate energy around the curvature of the earth by diffraction. This is commonly called  ground-wave propagation. A ground-wave radar can detect the same kind of targets as can a  sky-wave radar. 
 ORDER BISTATIC RADAR  LINE 
 The term reso- nant refers to the Fourier component of the surface where the water wavelength multiplied by the cosine of the grazing angle equals one-half of the radar wave- length. This type of scatter is frequently refered to as Bragg scatter. These mod- els are helpful in developing an understanding of the sea surface and the radio- wave interaction; however, a very long time average is implied when the water- wave spectrum is described as the product of two terms, one of which is frequency to the minus fifth power and the other an exponential with frequency in the argument. 
 !IR !DVANTAGES $ISADVANTAGES ,OW 02& -4)RANGE UNAMBIGUOUSDOPPLER AMBIGUOUS#AN SORT CLUTTER FROM TARGETS ON BASIS OF RANGE &RONT 
 It provides an unambiguous (unfolded) doppler spectrum by offsetting the rear reference before it is mixed with the front signal. ical components necessary for the inverse receiver are highly selective filters at IF frequencies and low-noise tunable microwave sources. The simplified block diagram of an inverse receiver is shown in Fig. 
 Asaresult, theantenna can berotated at4rpm and height- finding toarange of50statute miles isquite possible. A12°range of elevation angle can becovered. The antenna isshown inFig. 
 Table 22.6 summarizes the RF and mechanical characteristics of the Ball Seasat-class antennas. Ball Aerospace Systems Division designed an antenna for the low-altitude space- based radar (LASBR) mission.53 The 13.8- by 63.6-m array is a direct extension of space-proven Seasat and SIR-A technology with stringent constraints of array two- way sidelobe and beam skirt performance. The design features a single-axis deployable truss fabricated from graphite-epoxy microstrip honeycomb panels and passive 3-bit hybrid phase shifters at each of the 49,152 elements. 
 Cost, weight, and complexity is still an issue because multiple  phase centers necessary for adaptive array performance require multiple manifolds.  Usually, once a subarray is formed in the manifolds, it is digitized and multiplexed for  adaptive signal processing. Another important function is beam steering control (BSC). 
 Monopulsc tracking radar can he  employed to avoid the vulnerability of conical-scan tracking radars to modulations that cause  it to break lock in angle.  Passive ECM. The noise jammer and the repeater jammer were examples of active ECM. 
 ITY  MAINTAINABILITY  AND ANY OTHER SYSTEM REQUIREMENT THAT IS IMPORTANT FOR DECISION MAKING 5NFORTUNATELY  THIS IS NOT ALWAYS DONE "UYERS OF RADARS SHOULD BE ENCOUR 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar.  GROUND PENETRATING RADAR  21.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 dielectric variation, not necessarily involving conductivity, would also produce reflec - tions and that the technique, through the easier realization of directional sources, had  advantages over seismic methods. 
 R. G. Strauch, B. 
 52, pp. 157–166, 2004. 155. 
 It is capable of 3 MW of peak power over a 300 MHz bandwidth, with a  0.002 duty cycle, a 2-µs pulse width, and a gain of 33 dB. This tube is similar in many respects  to the V A-87 klystron amplifier. It was originally designed to he used interchangeably with the  VA-87 klystron, except that the VA-125 TWT has a broader bandwidth and requires a larger  input power because of its lower gain. 
 &  In particular I wish to record my thanks to the former  Ministry of Aircraft Production for the loan of docu-  ments. Thanks are also due to the Admiralty Signal  Establishment, to the Air Ministry, to Sir Robert  Watson-Watt, to Dr R. A. 
 The design is further complicated by the need for  structural strength, lightning protection, and protection from erosion by rain, hail, and dust. It  is not surprising therefore that the electrical performance of a radome must sometimes be  sacrificed lo accommodate these other factors.  A radome permits a ground-based radar antenna to operate in the presence of high winds. 
 21. 118. F. 
 310, pp. 983–985, 2005. 109. 
 It is noted that  the RWR detection performance is inversely proportional to R2 rather than to R4 of the  radar target detection equation. For this reason, the RWR can detect a radiating radar  at distances far beyond those of a radar’s own target detection capability. The radar- versus-interceptor problem is a battle in which the radar’s advantage lies in the use  of matched filtering, which cannot be duplicated by the interceptor (it does not know  the exact radar waveform), while the interceptor’s advantage lies in the fundamental  R2 advantage of one-way versus two-way radar propagation.15–18 Low probability of  intercept (LPI) techniques are applied to radar to win the battle of “to see and not to be  seen”: see Schleher19 and references therein. 
 34. F. Feindt, V . 
 TOR IS TO PUT THE BATCH AMPLITUDES THROUGH A MOVING 
 POLARIZED CASE  SINCE TWICE AS MUCH DATA ARE COLLECTED BY A QUAD 
 LATION   4HE USE OF LOW 
 Actual systems commonly  exceed these minimum requirements. Targets with a maximum relative speed of  100 kt must be trackable; this requirement is increased to 140 kt for radars on vessels  capable of more than 30 kt. On the bridge, the navigator’s requirements to aid colli - sion avoidance include the need to know a target’s closest point of approach  (CPA)  and time to closest point of approach  (TCPA), both of which must be available for  all tracked targets. 
   ,&- UNWEIGHTED o 
 The USA also then decided to standardise on ASG.1, which was the better radar, and this was designated as ASV Mk. V for use in aircraft of Coastal Command. A laterversion with higher power, ASG.3 or AN/APS-2 in the USA, was designated ASV Mk. 
 Queen: Modified Generalized Sign Test Processor for 2-D  Radar, IEEE Trans., vol. AES-10, pp. 574-582, September, 1974. 
 With a high-resolution radar  (nanoseconds pulse width) the individual sea-clutter spikes, as mentioned in Sec. 13.3, can  persist for several seconds, which is much greater than the 10 ms decorrelation time quoted for  S-band sea clutter. The persistence of these sea-clutter spikes makes difficult the detection of  small targets, such as buoys and small boats. 
 Skolnik, editor of this handbook, in his review of this chapter. C8 (DECIBELS) . FIG. 
   PP n  *ANUARY   4 " ! 3ENIOR  - ! 0LONUS  AND % & +NOTT  h$ESIGNING FOAMED 
 AP-21, pp. 628-639, September, 1973.  35. 
 In one nodding-beam height finder, up to 22  target-heights per minute can be obtained when the slewing is controlled automatically for  maximum data rate by the computer of the associated data-handling system. 29 The absolute  height accuracy ofa nodding-beam height finder can be± 1500 ft (460 m) at 150 nmi (280 km)  range.  The nodding-beam height finder is one of the oldest techniques for measuring the eleva­ tion angle of aircraft targets. 
 58. Beckmann, P .. and A. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Radar Transmitter. 10.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 33. 
 The basic ﬂowchart of phase compensation method based on fast minimum-entropy. 283. Sensors 2019 ,19, 1154 4. 
  
 TIME 
 In many radar applica- tions a detection is not said to occur until its track has been established. A radar with sufficient resolution in one or more coordinates can determine a target's size and shape. Polarization allows a measure of the symmetry of a tar- get. 
 Moyer, “Comments on ‘Receiver antenna scan rate requirements needed to implement  pulse chasing in a bistatic radar receiver,’” IEEE Trans. on Aerospace and Electronic Systems ,  vol. 38, no. 
 59.Hoft,D.J.,andM.B.Fishwick: AnalogWaveform Generation andProcessing. Electronic Progress, vol.17,no.I,pp;2-16,Spring,1975.(Published byRaytheon Co.,Lexington. Mass.) 60.Barton,D.K.:SputnikIIasObserved byC-BandRadar,1959IRENational COIIV.Rec.,vol.7,pt5, pp.67-73. 
 Parameters Description Product type Radarsat-2 WUF SLC Track no. 226 Band C Wavelength (cm) 5.5 Revisit frequency (day) 24 Incidence angle (degree) 30–50 Range resolution (m) 1.6 Azimuth resolution (m) 2.8 Orbit direction Descending We gathered data about natural and human factors that influence land subsidence. Two natural factors include soft soil and carbonate rock, see Figure 1. 
 Frazer, “High-resolution time-frequency distributions  for maneuvering target detection in over-the-horizon radars,” IEE Proc. Radar, Sonar, and  Navigation , vol. 150, pp. 
 Conventionally,  the array is end-fed, although center-fed alternatives are sometimes used.Class BeamwidthMinimum  Display SizeCoast-Line  Detection Range Point Target Detection Range Rising   to 60 mRising   to 6 m400 m2 7.5 m ht10 m2 3.5 m ht5 m2 3.5 m ht A ≤ 4.0° ≥ 150 mm 9 nm 5 nm 5 nm 2 nm 1 nm B ≤ 5.5°  ≥ 85 mm 5 nm 3 nm 3 nm 1 nm N/A C ≤ 7.5°  ≥ 75 mm 5 nm 3 nm 3 nm 1 nm N/ATABLE 22.2  Radar Performance Requirements for Small Craft ( Courtesy of IEC )* Radar ClassMaximum Sidelobe Level (dB) Within ±10° Within ±10° SOLAS –23 –30 Non-SOLAS Class A –20 –23 Non-SOLAS Classes B & C –18 –19TABLE 22.3  Antenna Sidelobe Performance Requirements ( Courtesy of IEC ) *  IEC 62252 ed.1.0 Copyright © 2004 IEC, Geneva, Switzerland. www.iec.ch. ch22.indd   10 12/17/07   3:02:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
   PP n    & 4 5LABY  " "RISCO  AND - # $OBSON  h)MPROVED SPATIAL MAPPING OF RAINFALL EVENTS WITH  SPACEBORNE 3!2 IMAGERY v )%%% 4RANS  VOL '% 
 TRAL SPREADTYPICALLY  TO  MSWHEREAS FIXED CLUTTER HAS A MUCH NARROWER SPECTRAL SPREADTYPICALLY LESS THAN  MS&)'52%  !PPROXIMATE DEPTH OF NULLS IN THE VELOCITY RESPONSE CURVE FOR PULSE 
   PP n   *ANUARY   0 3 0 7EI  ! 7 2EED  # . %RICKSEN  AND - $ "USHBECK  h3TUDY OF 2#3 MEASUREMENTS FROM  A LARGE FLAT PLATE v IN  0ROC TH !-4! #ONFERENCE  !NTENNA -EASUREMENT 4ECHNIQUES !SSOCIATION  3YMPOSIUM  .EWPORT  2)  /CTOBER     PP n  % & +NOTT  h! TOOL FOR PREDICTING THE RADAR CROSS SECTION OF AN ARBITRARY CORNER REFLECTOR v IN  )%%% 0UBL  )%%% 3OUTHEASTCON  #ONFERENCE   #( 
 The angle corresponding to the minimum reflection coefficient is called Brew- ster's angle.  The different reflection coefficients with the two polarizations result in different coverage  patterns. The nulls are not as deep with vertical polarization, nor are the lobe maxima as great. 
 Itisobvious that nearly alloftheenergy from thefeed will strike aproperly placed paraboloid, which will then collimate the radiation. Figure 9.4 shows theradiation from anincorrectly designed feed. Acorrect design, used inthe 3-cm band, isillustrated inFig. 
 The small vertically polarized fields produced by each slanted slot need to be sup - pressed as they can otherwise lead to high cross-polarized sidelobes from the array,  exacerbated by the phase reversal of the cross-polar component from slot to slot, caus - ing cross-polar grating lobes. This can be achieved with a printed polarization filter in  front of the array or by effectively creating, as part of the structure, a short length of  open-ended waveguide in front of each slot, with dimensions that make it below cutoff  for vertical polarization. Slot characterization is normally performed by measurement, rather than by  detailed electromagnetic analysis. 
 TER ECHOES WITHIN RANGE 
 SPREAD ECHOES ARE SO STRONG THEY  CAN INCAPACITATE A RADAR THROUGH ITS SIDELOBES u 'EOMAGNETIC STORMS AND SUB 
 Cost.  There were several consequences to the severe reduction in approved  funds relative to funds requested for the original Venus Orbiting Imaging Radar  (VOIR) mission. Rather than a conventional circular orbit, Magellan  was redesigned  for an elliptical orbit (Figure 18.16), which had considerably less associated costs  and risk. 
 This has been said to apply to stratiform rain. For  orographic rain Z = 31r1.71 and for thunderstorm rain Z = 486r1.37. Thus a single expres-  sion need not be used, and the choice of a Z-r relationship can be made on the basis of the type  of rain.70 Substituting Eq. 
 In general, little can be done in tube  design to reduce harmonic outputs, but it is feasible to filter out harmonics (30 to  60 dB reduction) with high-power filters. Adjacent-band spurious output can also occur in some cathode-pulsed TWTs and  CFAs. Adjacent-band spurious output is affected by tube and modulator selection, but  it can be filtered by a high-power microwave filter if necessary . 
 Re- printed in Barton, D. K.: "CW and Doppler Radars," vol. 7, Artech House, Norwood, Mass., 1978, sec. 
 FT WAVES 4HESE PAIRINGS ARE NOT CONSISTENT WITH THE VALUES FOR AN EQUILIBRIUM SEA DESCRIBED IN 4ABLE  AND INDICATE THE UNNOTICED OR UNRECORDED PRESENCE OF HEAVY SWELL OR HIGHLY NONEQUILIBRIUM WIND CONDITIONS OR BOTH %VEN WITH ALL THE VARIABLES PROPERLY SPECIFIED  RECORDED CLUTTER DATA CAN BE SPREAD OVER A WIDE DYNAMIC RANGE  ESPECIALLY AT LOW GRAZING ANGLES 3INCE SEA CLUTTER IS GENERALLY VIEWED AS A SURFACE 
 TIVE SPATIAL SUPPRESSION IS ALSO SHOWN DEMONSTRATING THE GOOD PERFORMANCE OF ADAPTIVE SPATIAL CANCELLATION 4HE REFERENCE  PROVIDES A COMPREHENSIVE STUDY  OF ANTI 
 It  is illustrated with hybrid-T (or magic-T) waveguide components. These are four-port  devices that, in basic form, have the inputs and outputs located at right angles to each  other. However, the magic T’s have been developed in convenient “folded” configu - rations for a very compact comparator. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 by the Cramer-Rao bound. 
   30!#% 
 Itwill benoticed that several extra stages areneces- sary toobtain this type oflimiting. The coherent oscillator circuit has already been described. The function ofthe“coherent oscillator locking test” channel willbediscussed inSec. 
 To obtain the target size or shape requires resolution in range and in angle. Good range  resolution is generally easier to achieve than comparable resolution in angle. In some radar  applications it is possible to utilize resolution in the doppler frequency shift as a substitute for  resolution in angle, if there is relative motion between the distributed target and the radar. 
 I.  Skolnik (ed.), McGraw-Hill Book Co., New York, 1970.  3~. 
 I_5 Doppler beam sharpening (DBS), 5.34 to 5.36, 5.37, 17.2, 17.3 Doppler, in bistatic radar, 23.14 to 23.17 Doppler filter bank, 2.7 to 2.9 Doppler filter straddle loss, 4.43 Doppler filter weighting loss, 4.43 Doppler radars, 4. 1 Doppler scintillation, in tracking radars, 9.36 to 9.37 Doppler shift, 1.10 Doppler spectra, spurious, 6.11 Doppler spectrum of ground echo, 16. 16 to 16.19 of HF sea echo, 20.49 to 20.52, 20.75 Doppler weather radar, 1.7 Ducts atmospheric, 26.7 to 26.10 elevated, 26.12 to 26.13 evaporation, 26.11 to 26.12 surface, 26.10 to 26.11 Duplexer, 1.2, 6.2 Dynamic range, 1.3, 6.4 to 6.8 of A/D converters, 6.38 to 6.39 and ECCM, 24.32 to 24.33 in pulse doppler radar, 24.32 to 24.33 E E-2C,  3.3 E-2D, 3.1 to 3.3 E region, 20.14 Early-late gate range tracking, 9.21 to 9.22 Eclipsing loss, 4.40 to 4.43, 5.18 Effective-earth-radius model, 26.15 Eldora radar, 19.37 to 19.38 EM system assessment, 26.18 to 16.23 Electronic Attack, 24.2 Electronic counter-countermeasures (ECCM) antenna-related, 24.10 to 24.31 decoys, 24.8 efficiency, 24.54 to 24.56 and imaging radar, 24.48 to 24.52 and ISAR, 24.51 to 24.52 operational-deployment techniques, 24.36 to 24.37 and over-the-horizon radar, 24.52 to 24.53 and phased array radar, 24.43 to 24.48 and radar equation, 24.55 to 24.56 receiver related, 24.32 to 24.33 role of the operator with, 24.36 SLB and SLC, 24.17 to 24.20 sidelobe canceler, 24. 
 M., et al.: Bistatic Radar Observation of Long Period, Directional Ocean- Wave Spectra with Loran-A, Science, vol. 170, pp. 158-161, October 1970. 
 SCAN PROVIDES AMPLITUDE 
 LIMITING PRIOR TO PULSE COMPRESSION ENCOUNTERED IN DIGITAL RADAR SYSTEMS 4HE 0 CODES CONTAINS  -   ELEMENTS AS DOES THE  &RANK CODE  BUT THE RELATIONSHIP OF THE ITH ELEMENT TO THE JTH GROUP IS EXPRESSED AS   FPIJ -- J J - I    ;   =;     = 
 4- 11. January. 1977. 
 6ELOCITY &ILTER ! HIGH RESOLUTION CLUTTER MAP IS BUILT FROM THE h 
 13.2] CATHODE-RAY TUBE SCREENS 481 cadium ratio governing the decay characteristics. ‘l’he blue layer is silver-activated zinc sulphide. Since itsdecay isvery rapid, anorange filter iscustomarily used toremove its“flash,” particularly atthefaster scanning rates. 
 Atfaster scanning rates itbecomes possible toprovide screens having carry-over from one scan tothenext. Within the requirements setby clarity inachanging picture, the longest obtainable persistence should usually beused inorder toaverage over thelargest possible number of pulses. However, the permissible decay time issoshort inthe case of very rapid scans that the operator and not the screen has the longer memory. 
 Each interrogating radar will receive not only the responses ofthebeacon toitsinterrogation pulses, but also thebeacon responses to interrogating pulses from other sets. The replies that aradar setreceives toitsown pulses are synchronous and appear atthe proper range ina regular way. Replies toother radar sets are, ingeneral, notsynchronous. 
 END DESIGN  WHERE IT IS COMMON TO HAVE BANDWIDTHS MUCH WIDER THAN THAT OF THE RADAR SIGNAL 4HERE ARE A LARGE NUMBER OF BROADCAST STATIONS THAT HAVE  
 The effective radiation pattern of the radar located at A in Fig. 12. l may be found in a  manner analogous to that of a two-element interferometer antenna formed by the radar  antenna at A and its image mirrored by the ground at A'. 
 Van Nostrand Reinhold Co.. New York, 1969.  128. 
 An aux- iliary horn is monitored in the search mode, using the receiver difference chan- nel, and compared with the main-antenna sum channel to prevent acquisition of large targets in the sidelobes of the main antenna. The auxiliary antenna has a peak gain which is about 20 dB less than that of the main antenna. Low-noise radio-frequency (RF) preamplifiers are used in the sum and difference channels. 
 175-182.  44. Kittredge, F., E. 
  AND  
 "EAM $IGITAL "EAMFORMING  !N IMPORTANT APPLICATION OF DIGITAL TECHNOL 
 MTI AND PULSE DOPPLER RADAR 107  reasonable physical length since the velocity of propagation of acoustic waves is about 10-5  that of electromagnetic waves. After the necessary delay is introduced by the acoustic line, the  signal is converted back to an electromagnetic signal for further processing. The early acoustic  delay lines developed during World War ll used liquid delay lines filled with either water or  mercury. 
 S. Reed: Adaptive Arrays in Airborne MTI Radar, IEEE Trans., vol. AP-24, pp. 
 15, pp. 12-14, August,  1976.  49. 
 Rott, N. On the viscous core of a line vortex ii. Zeitschrift für Angewandte Mathematik und Physik 1959 ,10, 73–81. 
 15. RAT-31S 3D Surveillance Radar, brochure, Selenia Radar and Missile Systems Divi- sion, Rome. 16. 
 FREQUENCY COMPONENTS  RESPECTIVELY CENTERED  AT  -(Z AND  -(Z 4HE  SECOND LINE OF &IGURE  SHIFTS THE )& SIGNAL BY ,/ FREQUENCY  -(Z USING SPEC 
 The insulator, which is the storage medium, is illuminated continuously by a "flood" beam.  When illuminated by the writing beam, charge is stored on the insulator surface because of  its secondary emission characteristics. The information written on the insulator storage  surface forms a charge pattern that is made visible by the action of the flood beam. 
 2.5.1. First Stage: Generation of Change Maps Using Unsupervised Feature Learning Two change maps are needed for a 2CMV representation of an SAR image pair. Each change map represents the changes that exist in the corresponding SAR image. 
   VOL     -ARTINEZ  ET AL  h-EASUREMENTS AND -ODELING OF 6ERTICAL "ACKSCATTER $ISTRIBUTION IN &OREST  #ANOPY v )%%% 4RANS ON 'EOSC AND 2EMOTE 3ENSING  VOL   PP n    2 "ERNARD AND $ 6IDAL 
 Therefore, two three-dimensional vortex models with an extra axial velocity have been proposed, i.e., the Burgers-Rott and the Sullivan vortex models. The Burgers-Rott vortex model is a spiral vortex instead of a two-cell vortex like that of the Sullivan vortex model. Due to the fact that the features of shear-wave-generated eddies mainly present as spirals in SAR images, the Burgers-Rott vortex model which can present the eddy spirals is most qualiﬁed to establish the current ﬁeld of the shear-wave-generated eddy. 
 Equation (14.32)mayhewritten S2-Dl Dr=2(5_Dbcostfie) (14.33) Theahoveequation locatesthetargetintheplaneoftheangletfi,..Thelocation ofthetargetin thethirddimension isfoundfromthemeasurement oftheorthogonal anglecoordinate 1/1() (notshowninFig.14.12). Whenthesum5=D,+Drapproaches thebase-line distance Db,theprolatespheroid degenerates intoa'straight linejoiningthetwofoci.Undertheseconditions, thelocation ofthe targetposition isindeterminate otherthanthatitliessomewhere alongthelinejoiningthe transmitter andreceiver. ,J Locating atargetwithbistaticradarisnotunlikelocating atargetwithmonostatic radar. 
 J. R. Riley, “Radar cross section of insects,” Proc. 
 %#&" .) $  )! $"  !#* /*-%  )#&"  0 %#&" .  !#*   ) $ )! $"1 
 The key step to phase compensation is estimation of φ(m). The phase error estimation ˆφ(m)is obtained by minimizing the entropy of ISAR image: ˆφ(m)=argmin E(I) (9) It means that the Equation (9) should be satisﬁed with (10): ∂E ∂φ(m)=0 (10) Since the total energy Sis constant, the cost function Ecan be redeﬁned as: E/prime(I)=−K−1 ∑ k=0N−1 ∑ n=0|I(k,n)|2ln|I(k,n)|2(11) Therefore Equation (10) is equivalent to: ∂E/prime ∂φ(m)=0 (12) The derivation function of the entropy with respect to φ(m)is obtained from (13): ∂E/prime ∂φ(m)=−K−1 ∑ k=0N−1 ∑ n=0[1+ln|I(k,n)|2]∂|I(k,n)|2 ∂φ(m)(13) Since|I(k,n)|2=I(k,n)I∗(k,n), there are: ∂|I(k,n)|2 ∂φ(m)=2Re(I∗(k,n)∂I(k,n) ∂φ(m)) (14) Then substituting Equation (14) into Equation (13), we have: ∂E/prime ∂φ(m)=−ReK−1 ∑ k=0N−1 ∑ n=0[1+ln|I(k,n)|2]I∗(k,n)∂|I(k,n)| ∂φ(m)(15) The derivative of I(k,n)with respect to ∂φ(m)is acquired as follows: ∂I(k,n) ∂φ(m)=−jR(k,n)exp(−jφ(m))exp(−j2π Mkm) (16) Substituting Equation (16) into (15), one obtains: ∂E/prime ∂φ(m)=−2MIm{exp[−jφ(m)]w∗(m)} (17) where: w(m)=K−1 ∑ k=0R∗(k,n)Rl (18) 282. Sensors 2019 ,19, 1154 Rl=1 MM−1 ∑ m=0[1+ln/vextendsingle/vextendsingle/vextendsingleI(k,n)2/vextendsingle/vextendsingle/vextendsingle]I(k,n)exp(j2π Mkm) (19) Finally, Equation (17) is equal to zero, and ˆφ(m)is obtained: exp(−jˆφ(m)) =w(m) |w(m)|(20) 3.3. 
 On the ocean this means that tiny ripples are more important than waves that are meters high; the same applies for land-surface scatter. As originally developed, this theory was for perturbations to horizontal flat surfaces, but it was soon modified to handle surfaces with large-scale roughness. The large-scale roughness was assumed to cause a tilting of the flat surface to which the small-perturbation theory could be applied. 
 D.: Investigation and Application of Radar Techniques for Low-Altitude Target Track-  ing. IEE ltrtrrt~atiotral Radar Corrjeret~ce, RADAR-77, London, Eng., Oct. 25-28, 1977, IEE Confer-  ence Publication No. 
 Digital Pulse Compression.  Pulse compression is another signal processing  function that is predominantly being performed digitally in radar systems. However,  at this writing, many systems still exist with analog-delay-line pulse compressors. 
 The operation of data processing may loss original information and amplify noise information. Sometimes, random crop may lose some important information. When the main information of images diverges of the center, using random crop cannot perform well, as shown in Figure 6, the bow and the stern of the ship have been cut. 
 1959. 115.Miller,C.J.:Minimizing theEffectsofPhaseQuantization ErrorsinanElectronically Scanned Array."Proceedings ofSymposium onElectronically Scanned ArrayTechniques andApplications," ROllleAirDel'e[op'llellt CellterTecllllical DOC!lIIlelltary ReportNo.RADC-TDR-64-225, vol.I, rp17JR.July.1964. 116.(·hampinc. 
 ANTENNA 
 NOISE POWER IN A SINGLE RANGE  GATE IN THE RECEIVER CAN BE APPROXIMATED FROM %Q  BY SUBSTITUTING THE RANGE GATES INTERSECTED AREA CS @COS   2PAZ  WITHIN THE MAIN BEAM ON THE GROUND FOR  D! AND SUM 
 TileRadioandElectronic Engineer. vol.39. pp.172176.March. 
 W. Sutton, and  very soon remarkable radar circuits were developed to  enable these new creators and receptors of ultra~high  frequencies to be used to best advantage.  For a detailed study of the progress in development  of these valves and other generators of very high fre-  quencies I recommend reference to the Institute of  Electrical Engineers Radar Convention papers, especially  Work on the Cavity Magnetron, by J. 
 RECEIVER TRIANGLE  CALLED THE  BISTATIC TRIANGLE 4HIS TRIANGLE LOCATES THE TARGET  USUALLY IN TERMS OF A RANGE AND ANGLE REFERENCED TO THE RECEIVE SITE /THER LOCATION SCHEMES ARE GIVEN IN 3ECTION  7HEN SEPARATE TRANSMIT AND RECEIVE ANTENNAS ARE AT A SINGLE SITE  AS IS COMMON IN  #7 RADARS  THE RADAR HAS CHARACTERISTICS OF A MONOSTATIC RADAR  AND THE TERM  BISTATIC  IS NOT USED TO DESCRIBE SUCH A SYSTEM )N SPECIAL CASES  THE ANTENNAS CAN BE AT SEPA 
   SURVEILLANCE SYSTEM v  )2% 4RANSACTIONS ON -ILITARY %LECTRONICS  VOL -), 
 cathode, and input and output ports. A schematic of a CF A is as shown in Fig. 6.12. 
 Amplitude-Comparison Monopulse. A method for visualizing the operation of an amplitude-comparison monopulse receiver is to consider the echo signal at the focal plane of an antenna.5 The echo is focused to a "spot" having a cross-section shape approximately of the form J1(X)IX for circular apertures, where J1(X) is the first-order Bessel function. The spot is centered in the focal plane when the target is on the antenna axis and moves off center when the target moves off axis. 
 TIONS ABOUT THE AVERAGE (OWEVER  ANALYSIS OF 3HUTTLE )MAGING 2ADAR 3)2  DATA PERMITS SOME ESTIMATES TO BE MADE OF THE VARIABILITY TO BE EXPECTED FOR DIFFERENT SIZES OF ILLUMINATED FOOTPRINT 4HE GENERAL CHARACTERISTICS OF RADAR BACKSCATTER OVER THE RANGE OF ANGLES OF INCI 
 ,   vol. 44, pp. 285–300, 2005. 
 When synchronization isexternal, the oscillator must beshock- excited. Figure 13.38 illustrates anLC-oscillator widely used inmedium- precision applications. When VIisconducting, the circuit isquiescent and energy isstored intheinductance byvirtue ofthe cathode current. 
 Another widely used method employs acylindrical rejlector, shaped like theblade ofasnowplow orbulldozer, and having only single curvature (Fig. 9“8). Such areflector isilluminated bythe radiation from alinear feed rather than apoint feed. 
 The binary integrator is also known as the dual-threshold detec - tor, M-out-of-N detector, or rank detector (see “Nonparametric Detectors,” later in this  section), and numerous individuals have studied it.14–18 As shown in Figure 7.3 d, the  input samples are quantized to 0 or 1, depending on whether or not they are less than  a threshold T1. The last N zeros and ones are summed (with a moving window) and  compared with a second threshold T2 = M. For large N, the detection performance of  this detector is approximately 2 dB less than the moving-window integrator because  of the hard limiting of the data, and the angular estimation error is about 25 percent  greater than the Cramer-Rao lower bound. 
 Local-oscillator noise can beminimized bythe use ofahigh intermediate frequency; however, thebalanced mixer (cf.Vol. 16ofthis series) provides abetter solution tothis problem. Many ofthepresent AFC systems require the use ofahigh intermediate frequency toprevent locking onthe wrong sideband. 
 13-14, January, 1973.  9. Shigemoto, J.: Balanced Mixer Noise Considerations, Microwave J., vol. 
 ASV Mk. VIA scanner, mounted in the nose of the aircraft [ 10]. Figure 4.22. 
 Thepost-detection integration lossdescribed byFig.2.8assumes aperfectintegraior. Manypractical integrators, however, havea"lossofmemory" withtime.Thatis,theampli­ tudeofasignalstoredinsuchanintegrator decays,sothatthestoredpulsesarenotsummed withequalweightasassumed above.Practical analogintegrators suchastherecirculating delayline(alsocalledafeedback integrator), thelow-pass filter,andtheelectronic storage tubeapplywhatisequivalent toanexponential weighting totheintegrated pulses;thatis,if11 pulsesareintegrated, thevoltageoutoftheintegrator is Nv=LViexp[-(i-l)y] 1=1(2.34) whereViisthevoltageamplitude oftheithpulseandexp(-y)istheattenuation perpulse.In arecirculating delay-line integrator, e-Yistheattenuation around theloop.InanRC low-pass filtery=Tp/RC,whereTpisthepulserepetition periodandRCisthefiltertime constant. Inordertofindthesignal-to ..noiseratioforagivenprobability ofdetection andprobabi­ lityorfalsealarm,ananalysis similartothatusedtoobtainFigs.2.7and2.8shouldhe. 
 At lower radar frequencies  and in less turbulent atmosphere, B may be smaller, and proportionately longer time  samples are necessary; thus, for short time samples of radar performance, significant  statistical variations must be expected. To convert sang expressed in linear units measured at the target to angular units for  a radar at range r, the following relation may be used: sang (angular mils) = sang (m)/r(km) Because the angular errors caused by angle noise are inversely proportional to  range, angle noise is of concern mainly at medium and close ranges. The resultant  tracking noise can be reduced by lowering the servo bandwidth to reduce the radar’s  ability to follow the higher-frequency components of the noise. 
 (Copyright 1956, IEEE; after Ref. 16.) S/N (dB) FIG. 8.10 Comparison of binary integrator (M out of AO with other integration methods (Pfa = HT10; PD = 0.90). 
 The two-frequency CW technique for measuring range was described as using the dopplzr  frequency shift. When the doppler frequency is zero, as with a stationary target, it is also  possible, in principle, to extract the phase difference. If the target carries a beacon or some  other form of echo-signal augmentor, the doppler frequency shift may be simulated by trans-  lating the echo frequency, as with a single-sideband modulator. 
 2.7 applies for a single pulse only. However, many pulses  ;it c 11sl1;11ly IC'IIII IIC'CI 11 0111 ;~riy 1x11 tic~lli~r tar gct oti each radar scari and can be used to iri~prove  dctcctloti I lie rir~rril~cr of ~~r~lscs~r~, rcturlicd from a point target as the radar antellria scaris  tIiro\~gIi rt~ 1~~;111iwidtl1- IF 1  - -7 -. -  'Is- @ 69-b (2.30)  wlierc On = antenna bearnwidtli, deg  1, = pulse repetiliori frequency, Hz  0, = antenna scanning rate, deg/s  (I),,, = antenna scan rate, rpm  Typical parameters for a ground-based search radar might be pulse repetition frequency  300 Hz, 1.5" beamwidth, and antenna scan rate 5 rpm (30'1s). 
 BEAM SYSTEM !NOTHER ADVANTAGE HAS TO DO WITH DYNAMIC RANGE )N AN ANALOG BEAMFORMING SYS 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25   blind folio 25.40 ch25.indd   40 12/20/07   1:40:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 1037–1044, 1980. 152. W. 
 351–361. 28. L. 
 The three signals may sometimes be com- bined in other ways to allow use of a two-channel or even a single-channel IF system as described later in this section. Monopulse-Antenna Feed Techniques. Monopulse-radar feeds may have any of a large variety of configurations. 
 178 THE GATHERING AND PRESENTATION OFRADAR DATA iSEC.69 station performance was never predictable from theory. Itwas always necessary to“calibrate” astation byanelaborate series oftest flights. The maximum reliable range ofaCH station was usually about 120 to150miles onsingle aircraft, but therange depended very much onthe skill oftheoperator and ofthemaintenance crew aswell asonmeteoro- 40,000// 330,000///.s /z20,000 - /,* =10,000 -.“ ~.//-/ O10‘;O- ’30 40 5060 7080 90100 110120 Rangeinmiles FIG. 
 L. N.: " Radar System Engineering." vol. I. 
 Bamler, R. A comparison of range-Doppler and wavenumber domain SAR focusing algorithms. IEEE T rans. 
 34, L02802, doi:10.1029/ 2006GL027889, 2007. 136. R. 
 It would not be possible to maintain clutter rejection in an MTI (moving-target indicator) or pulse doppler radar if the spectrum of clutter echoes were to spread into the spectral region in which target returns were expected.13'15 In a lin-log (linear-logarithmic) receiver the output signal amplitude is closely proportional to the logarithm of the envelope of the RF input signal amplitude for high input signal amplitudes, while the output signal amplitude is directly propor- tional to the envelope of the RF input signal amplitude for low input signal am- . CHAPTER 10 PULSE COMPRESSION RADAR Edward C. Farnett George H. 
 Van Vleck, J. H., and D. Middleton: A Theoretical Comparison of Visual, Aural, and Meter Reception  of Pulsed Signals in the Presence of Noise, J. 
 ASPECT COVERAGE REQUIRES GOOD PERFOR 
 Orographic53 rain is precipitation that is  induced or influenced by hills or mountains, whereas Thunderstorm53 rain is typical of  convective precipitation systems. In each of the above expressions, Z is in mm6/m3 and  R is in mm/h. In Eq. 
 BASED OR FIRST PRINCIPLES MODELS   SUCH AS 535 '!)-  *0,53# '!)-   3!-) DEVELOPED BY (UBA AND *OYCE  AND +HATTATOVS MODEL  SOLVE THE PLASMA  DYNAMICS AND COMPOSITION EQUATIONS GOVERNING EVOLUTION OF DENSITY  VELOCITY  AND  TEMPERATURE FOR VARIOUS ION SPECIES ON A GLOBAL $ GRID  SUBJEC T TO THE %ARTHS MAG 
 A  matching structure, designed from the simulator impedance data, may be placed into  the simulator to measure its effectiveness. Several simulator designs, results, and a  complete discussion of the topic have been presented by Hannan and Balfour.59 The  technique is limited in that only discrete scan angles can be simulated. Several scan  angles in both planes of scan give a general idea of the array impedance.FIGURE 13.14  Array simulator terminated with two dummy elements FIGURE 13.15  Rectangular- and triangular-array geometries  with simulator boundaries superimposed: ( a) square array with  simulator superimposed and ( b) triangular array with simulator  superimposed ch13.indd   26 12/17/07   2:39:58 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 22). The production ofamovable index bythe contactor orphotocell method requires that the differential setting bemade mechanically. This method isseldom used unless the indicator contains amechanical repetition ofthescanner motion. 
 154, pp. 967-972, 1966.  105. 
 They have some interesting properties as compared to  the microwave vacuum tube, but the individual devices are inherently of low power.  There is no one universal transmitter best suited for all radar applications. Each power-  generating device has its own particular advantages and limitations that require the radar  system designer to examine carefully all the available choices when configuring a new radar  design. 
 A. Biddison, S. F. 
 L.: Three-dimensionai Air Surveillance Radar, Systems Technology, no. 21, pp. 29-33,  June, 1975. 
 The ratio involves the square because of ttlc  two-way transit.  When there are a large number of pulses per beamwidth integrated, the scanning loss is  generally taken to be 1.6 dB for a fan beam scanning in one coordinate and 3.2 dR whcn  two-coordinate scanning is ~sed.~'-~'  When the antenna scans rapidly enough that the gain on transmit is nor tile same as tllc  gain on receive, an additional loss has to be computed, called the scatlt~it~g loss. The technique  58INTRODUCTION TORADAR SYSTEMS gas-tube duplexer alsointroduces losswheninthefiredcondition (arcloss);approximatcly 1dBistypical. 
 1969. ..  15. 
 K. Fung, Microwave Remote Sensing, Active and Passive ,   V ol. III, Reading, MA: Addison-Wesley Publishing Company, 1986, Sec. 
 A. K. Fung, Microwave Scattering and Emission Models and Their Applications . 
 SEC. 143] DIRECT-DRIVEN ALTERNATORS 557 14.2. Wave Shape.-4ince allelectric power used forradar iscon- verted todirect current orisused forheating, there isnoinherent require- ment for sinusoidal wave shape. 
 Laser Frequencies. Coherent power of reasonable magnitude and effi- ciency, along with narrow directive beams, can be obtained from lasers in the infrared, optical, and ultraviolet region of the spectrum. The good angular resolution and range resolution possible with lasers make them attractive for target information-gathering applications, such as precision ranging and imaging. 
 118. U. Germann and J. 
 7.2 ASV Mk. II and III In March 1942, trials took place at Ballykelly, Northern Ireland, to determine therelative merits of ASV Mk. IIA (the high power variant of ASV Mk. 
 224-226 Gaseous discharge phaseshifter,297 Gaussian probability densityfunction. 22 Geodesic dome.265 Glint.168-172 Grating lobes.281,283.300,332 Grazing angle.473 Grid-controlled tubes,213 Ground-wave OTHradar,536 Half-wave wallradome, 267 Hard-tube modulator, 215-216 Heightfinderradar,541-546 Helicalscan,177,545 Hemispherical coverage arrays,328-329 HFOTHradar,529-536 High-range-resolution monopulse, 181-182. High-range-resolution radar.434-435 Hologram. 
 Stewart, C. H., and G. J. 
 EFFECTIVE WHEN THE REQUIRED RADAR SYSTEM AVERAGE POWER CAN BE PROVIDED BY A LOWER PEAK POWER AT A HIGHER DUTY CYCLE !S A RESULT  THERE HAVE BEEN RELATIVELY FEW DIRECT REPLACEMENTS OF OLDER LOW DUTY CYCLE TRANSMITTERS BY SOLID 
 A pair of pulses is used in the  frequency-agile system, and target returns are processed by a moving-target detector.  The pulse pair consists of a 1-µs single-tone pulse that provides coverage to 8 nmi and  a 100-µs nonlinear chirp pulse that provides coverage to 80 nmi. The 100-µs pulse is  compressed to 1 µs such that high duty cycle is achieved without compromising range  resolution. 
 In order to further illustrate the accuracy of the Doppler parameter estimation, Table 5shows the estimation results of the errors of the Doppler parameters based on the basic MAM method, the IMAM method, and the EMAM method. It can be seen that the estimation results of ˆedr0based on the three methods are relatively close to the real values, and likewise for the estimation results of ˆe3rd0by the basic method and the EMAM method. The IMAM method and the EMAM method can estimate ˆedr1 well. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 14.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 is identical to that of a flat plate whose physical area matches the effective area of the  corner reflector. 
 In space,radarhasassisted intheguidance ofspacecraft andfortheremotesensingofthelandandsea. Themajoruserofradar,andcontributor ofthecostofalmostallofitsdevelopment, has beenthemilitary: although therehavebeenincreasingly important civilapplications, chieny formarineandairnavigation. Themajorareasofradarapplication, innoparticular orderof importance. 
 K. Moore, “Identification of major backscattering sources in trees  and shrubs at 10 GHz,” Remote Sensing Environ. , vol. 
 1183–1197, 1990. 72. R. 
 TER USING HIGH 
 RANGE SCALES ARE SELECTED 4HE SYMBOLOGY OF THIS GRAPHIC  TOGETHER WITH ALL OTHER SYMBOLS AND ABBREVIATIONS ON THE DISPLAY  SHOULD MEET )-/ REQUIREMENTS  4HIS ENSURES THAT OPERATORS ARE FAMILIAR WITH THE RADAR PRESEN TA 
 Factorization of the Ambiguity Function. Let it be assumed that f(f) can be written . M = g(t)e^ (21.22) In this equation, g(t) is considered a complex function having both magnitude and phase, whereas O)0 represents a carrier frequency. 
 Since tl\ese fan bearns do not illuminate the surface they do not suffer from  multipath problerns.  Phase in space. This technique employs a single reflector with a rather unique type of feed. 
 Clarke, “Airborne radar” Parts 1 & 2, Microwave Journal , p. 32 and p. 44, January 1986 and  February 1986. 
 3.4 AIRBORNE DOPPLER NA VIGATION43 -s6  An important requirement of aircraft flight is for a self-contained navigation system capable of  operating anywhere over the surface of the earth under any conditions of visibility or weather.  It should provide the necessary data for piloting the aircraft from one position to another  without the need of navigation information transmitted to the aircraft from a grour:d station  One method of obtaining a self-contained aircraft navigation system is base_d 01 the CW  doppler-radar principle. Doppler radar can provide the drift angle and true spe d of the  aircraft relative to the earth. 
 POWER STAGES OF AN AMPLIFIER CHAIN  WHERE IT MAY OFFER AN ADVANTAGE IN  EFFICIENCY  OPERATING VOLTAGE  SIZE ANDOR WEIGHT COMPARED TO OTHER TUBES 4HE OUTPUT 
 Plate V (p. 129). The Operation of Gee Radar. 
 END SYSTEM NOISE  WHICH IS TYPICALLY ALLOWED TO TOGGLE TWO OR MORE BITS FOUR OR MORE QUANTIZATION LEVELS  OF THE !$# OUTPUT !LSO  AN ACTUAL . 
 TION  5NIVERSITY OF +ANSAS  ,AWRENCE    * - 3TILES AND + 3ARABANDI  h%LECTROMAGNETIC SCATTERING FROM GRASSLAND0ART ) ! FULLY PHASE 
 TRATED TO THE GROUND SURFACE AT FREQUENCIES BELOW ABOUT  '(Z .EVERTHELESS  THE MODEL INDICATES THE KIND OF RESULTS TO BE EXPECTED FOR THIS IMPORTANT SITUATION 4ABLE  GIVES THE RESULTING CONSTANTS TO USE IN %Q A .   '2/5.$ %#(/  £È°ÎÎ 3NOW SCATTER DEPENDS STRONGLY  ON THE FREE 
 Wiley & Sons Inc., 1998. ch18.indd   63 12/19/07   5:15:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Pilon, R. O., and C. G. 
 Domville also summarized in-plane data for forest and urban areas.108 The shape of constant cr^0 contours for all Domville's terrain types are similar. For urban areas a#° is generally 3 to 6 dB higher. The extent of the specular ridge is smaller, however. 
 TER CAN CREATE RETURNS THAT WOULD EXCEED THE DYNAMIC RANGE OF THE RECEIVER 4HE SPATIAL  AREA OCCUPIED BY SUCH CLUTTER IS TYPICALLY A VERY SMALL FRACTION OF THE RADAR COVERAGE  SO CLUTTER MAP !'# HAS BEEN USED AS AN ALTERNATIVE TO BOOSTING THE 34# CURVE 4HIS TECHNIQUE USES A DIGITAL MAP TO RECORD THE MEAN AMPLITUDE OF THE CLUTTER IN EACH MAP CELL OVER MANY SCANS AND ADDS RECEIVER ATTENUATION WHERE NECESSARY TO KEEP THE CLUTTER RETURNS BELOW THE SATURATION LEVEL OF THE RECEIVER 0ROGRAMMABLE 'AIN #ONTROL  2EDUCED GAIN MAY BE DESIRABLE IN A VARIETY OF  SITUATIONS SUCH AS HIGH CLUTTER OR HIGH INTERFERENCE ENVIRONMENTS OR IN SHORT RANGE MODES &IXED ATTENUATION IS OFTEN PREFERABLE TO 34# OR CLUTTER MAP CONTROL (IGH 02& PULSE DOPPLER RADARS  FOR EXAMPLE  CANNOT TOLERATE 34# DUE TO THE RANGE AMBIGUITY OF TARGETS !DDITIONAL ATTENUATION MAY BE PROGRAMMED EITHER MANUALLY VIA OPERATOR CONTROL OR AUTOMATICALLY TO INCREASE THE RECEIVERS LARGE SIGNAL HANDLING CAPABILITY OR TO REDUCE ITS SENSITIVITY 'AIN .ORMALIZATION  2ECEIVER GAIN CAN VARY DUE TO COMPONENT TOLERANCES  FRE 
 Macfadzean, Surface Based Air Defense System Analysis , self-published, 1992 & 2000,   pp. 213–243. 76. 
 In the  forward-bias (conducting) state, when appreciable current is passed, the injection of holes and  electrons from the P and N regions respectively, creates an electron-hole plasma in what was  formerly the dielectric region. The slightly lossy dielectric is changed to a fairly good conduc­ tor with the application of forward bias. The capacitive component of the circuit disappears  and the equivalent circuit becomes a small resistance which decreases in value with increasing  forward current. 
 DAY REPEAT OF 2!$!23!4  ALTHOUGH A  NON 
      &)'52%  -AGNITUDE RESPONSE OF LOWPASS FILTERS . È°Ón  2!$!2 (!.$"//+  &)'52%  'ROUP DELAY RESPONSE OF LOWPASS FILTERS &)'52%  .ORMALIZED IMPULSE RESPONSE OF LOWPASS FILTERS . 
 Nathanson and Reilly10 have shown that the clutter spectral width of rain is pri - marily due to a turbulence and wind shear (change in wind velocity with altitude).  Measurements show a typical average value of s vt = 1.0 m/s for turbulence and  s vs = 1.68 m/(s/km) for wind shear. A convenient equation is σ θvs el = ⋅ ⋅ 0 04.R  m/s   for the effect of wind shear, provided the rain fills the vertical beam. 
 FUL TO CORRECT MODULE 
 SEARCH-4)  MOVING TARGET INDICATION-44  MULTIPLE 
 WAY ILLUMINATION FUNCTION ENCOUNTERED IN ANTENNA WORK  THE ARGUMENT  X FOR THE FLAT PLATE INCLUDES A TWO 
 Thetracking techniques discussed thusfarinthischapter were hased 011acomparison ofthe1lI111,1il/ldl'sofechosignalsreceived fromtwoormoreantenna positions.Thesequential-Iobing andconical-scan techniques usedasingle,time-shared alltcllna heam,whilethemOllopulse technique usedtwoormorcsimultancous beams.The differencc inamplitudes intheseveralantenna positions wasproportional totheangularerror. Theangleofarrival(inonccoordinate) mayalsobedetermined bycomparing thephase difference betwecn thcsignalsfromtwoseparate antennas. Unliketheantennas ofamplitude­ comparison trackers, thoseusedinphase-comparison systemsarenotoffsetfromtheaxis.The individual boresight axesoftheantennas areparallel, causing the(far-field) radiation to illuminate thesamevolumeinspace.Theamplitudes ofthetargetechosignalsareessentially thesamefromeachantcnna heam,butthephasesaredifferent. 
 98. Flock, W. L.. 
 The magnetron is a crossed-field device in that the electric field is perpendicular to a static  magnetic field. Although the name magrletrorl has been applied in the past to several different  electron  device^,^ it was the application of cavity resonators to the magnetron structure that  permitted a workable microwave oscillator of high power and high efficiency.  Conventional magnetron. 
 However, these methods all require the use of full-polarization data. In addition to the polarization characteristic, the scattering intensity is also aspect-dependent. Therefore, we can obtain the scattering behavior by using single-polarization CSAR data. 
 ENT DISTORTIONS BECAUSE THEY ARE ANGLE 
 (From Von Aulock1S, Courtesy Proc. IRE.) . 1111' HITIHONICAI.I.Y SIHRED PIIASl'D ARRAY ANTENNA I~ RADAR 285  Ilic O coordinate. 
 SENSE ANGLE 
 TUATIONS ON THE ERROR DETECTOR OUTPUT #ONSEQUENTLY  A WIDE SERVO BANDWIDTH  WHICH REDUCES LAG ERRORS  ALLOWS THE NOISE TO CAUSE GREATER ERRONEOUS MOTIONS OF THE TRACKING SYSTEM 4HEREFORE  FOR BEST OVERALL PERFORMANCE  IT IS NECESSARY TO LIMIT THE SERVO BAND 
 3.28 in a radar system provides numerous options and com - plications. The options range from a fully adaptive solution across all available antenna  elements and all pulses in a coherent processing interval (CPI), to reduced degrees of  freedom solutions in order to be practical. The fully adaptive solution also encounters  problems in the real-world where the interference environment is not well behaved  (e.g., homogenous clutter). 
 336 THE MAGNETRON AND THE PULSER [SEC. 10.4 anode segments and thus transferring charge from the cathode tothe anode. The r-fcurrent setupinthe oscillators isprincipally adisplacement current produced bythis rotating space charge. 
 The Nyquist rate is the signal’s two-sided bandwidth irrespective of  the particular portion of the spectrum in which the signal resides. Therefore, for this  signal the Nyquist frequency is B even though the signal contains components at actual  frequencies greater than B. Figure 25.5 b shows the result of sampling this signal at FIGURE 25.4 (a) Bandlimited lowpass signal spectrum before sampling, ( b) aliased lowpass signal  spectrum after sampling at rate fs < B, and ( c) aliased sampled signal spectrum0 B/2fs 2fsfreq freq(a) (b) (c)–fs –2fs 0 B/2fsALIASING 0 B/2fs 2fs –fs –2fs–B/2 –B/2 FIGURE 25.5 (a) Bandlimited, real passband signal spectrum before sampling and ( b) signal spectrum  after sampling0 B/2 B 2B –B –2B0 B 2B –B –2Bfreq freq(a) (b)B/2 B/2 –B/2 ch25.indd   4 12/20/07   1:39:50 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 G. Malech, Chapters 2–4 in Microwave Scanning Antennas , R. C. 
 Itisinteresting tonotice that, before theadvent ofthePPI, users of such equipment asthe CXAIU and theSCR-270 frequently constructed aplan display with pencil and paper, plotting inpolar coordinates the targets whose range and azimuth were called offbythe radar operator. Further, skilled operators ofsuch sets developed anability toform, by watching the.A-scope, asort ofmental PPI picture ofthe radar targets, remembering from scan toscan their ranges and bearing angles. When thePPI became available, the operator was released from this necessity, and could apply hisskills toamore sophisticated mental appreciation ofthetarget situation; forexample, agood PPI operator will often keep inhismind thedirections inwhich important targets aremoving. 
 ING THE RETURN PULSE WITH THE MATCHED FILTER OF EACH RANGE GATE &OR A SINGLE RANGE GATE  THIS IS SIMPLY THE CONVOLUTION OF TWO RECTANGULAR PULSES  WHICH RESULTS IN A TRIANGULAR RESPONSE 4O COMPUTE LOSS  THE MATCHED FILTER OUTPUT IN TERMS OF POWER IE  VOLTAGE SQUARED  MUST BE USED 7HEN THE 02& IS HIGH  SO THAT MANY RANGE AMBIGUITIES OCCUR  THE TARGET RANGE DELAY  MAY BE CONSIDERED TO BE RANDOM FROM FRAME TO FRAME  WITH A UNIFORM DISTRIBUTION OVER THE )00 ! MEASURE OF PERFORMANCE REDUCTION DUE TO ECLIPSING AND RANGE GATE STRADDLE IS FOUND BY  5SING THE UNECLIPSED DETECTION CURVE  0 D VS 3.  FOR THE WAVEFORM AND SELECT 
 14.10; see also Sec. 15.3. 74.3 UNMODULATEDCWRADAR Spectral Spreading. 
  AIRBORNE RADAR OPER 
 ¯ PPP ;   COS  =     3INCE  FREQUENCY MODULATION IS PROPORTIONAL TO THE TIME DERIVATIVE OF PHASE  PHASE  IS OBTAINED BY INTEGRATING THE FREQUENCY WITH RESPECT TO TIME  4HE EXPRESSION FOR FRE 
 ]ÊÊ   Ê-* 
 Toprotectthereceiver undertheseconditions, amechanical shuttercanbeusedtoshort­ circuittheinputtothereceiver whenever theradarisnotoperating. Theshuttermightbe designed toattenuate asignalby25to50dB. TheTRisnotaperfectswitch;sometransmitter poweralwaysleaksthrough tothe receiver. 
 ING THREE BEAMS 3UM  $ELTA AZ  AND /MNI  BY WEIGHTING AND SUMMING THE  RECEIVE  CHANNELS OVER THREE PULSES TO PROVIDE SIMULTANEOUS CLUTTER AND JAMMING CANCELLATION 4HE ADAPTIVE WEIGHT ALGORITHM IS MATCHED TO THE RADARS OPERATING PARAMETERS AND IS AUGMENTED WITH ADAPTIVE KNOWLEDGEnAIDED SAMPLING SCHEMES TO MAXIMIZE PERFOR 
 SCALE MECHANISM  SUCH AS A FRONTAL OR MONSOON SITUATION ! VERTICAL  VARIATION OF 2 OF THE FORM   22 EDH 
 A relatively small  buttdle of chaff can form a cloud with a radar cross section comparable to that of u large  aircraft.  Chaff is used either to deceive or to confilse. Sl~or cv/ic!lj'is tile nilme ~rst~aily associated wit11  t1te ~Ieceptio~l role, while col.ritlor c/ic!lj'is a conl'ilsion cotl1ltesrncast11'e. 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 24.58  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 NLI Noise Like Interference OTH Over The Horizon PAR Phased-Array Radar PDR Phase Difference Rate PDW Pulse Description Word Penaids Penetration Aid Decoy PPI Plan Position Indicator PRF Pulse Repetition Frequency PRI Pulse Repetition Interval PSLR Peak-to-Side Lobe Ratio RCS Radar Cross Section RF Radio Frequency RFI Radio Frequency Interference RFM Range Filter Map RGPO Range Gate Pull Off RWR Radar Warning Receiver Rms Root Mean Square RWS Radar Work Station RX Receiver SAR Synthetic Aperture Radar SAW Surface Acoustic Wave SINR Signal-to-Interference plus Noise Ratio SLB SideLobe Blanking SLC SideLobe Canceler SNR Signal-to-Noise Ratio SOJ Stand Off Jammer SP Self-Protection SSJ Self-Screening Jammer STAP Space-Time Adaptive Processing STT Single Target Tracker ToA Time of Arrival TSI Terrain Scattered Interference TV-SAP Time-Varying Spatial Adaptive Processing TWS Track While Scan UHF Ultra High Frequency ULA Uniform Linear Array VGPO Velocity Gate Pull Off VHF Very High Frequency VLSI Very Large Scale Integration ACKNOWLEDGMENTS The Author wishes to warmly thank his colleagues for their cooperation in this work:  Dr. L. 
 37. Boyd, C. R., Jr.: Comments on the Design and Manufacture of Dual-Mode Reciprocal Latching  Ferrite Phase Shifters, I £EE Trans., vol. 
 WORK OF OVER THIRTY  AND  -(Z WIND PROFILERS IN THE CENTRAL 5NITED 3TATES USING SOLID 
 The signal processor will generate waveforms for transmission by the seeker or data  link. It will also measure target range, angle, doppler, and so on, and provide those to  the other platform. The MFAR signal processor sends motion sensing and navigation  estimates to correct measurements; to track, encode, and decode datalink messages;  and to perform jammer nulling. 
 D. H. Sinnott, “The Jindalee over-the-horizon radar system,” Conf. 
 Since  they provide relatively large passband droop and slow stopband rejection, they are  generally followed by a FIR filter that can both correct for CIC passband droop and  FIGURE 6.21  Digital downconversion architectureA/DD1 x(t) Q(k)I(k) h1(n) cos(w0n)D1sin(w0n) )(~nx h1(n)h2(m) h2(m)D2D2 ch06.indd   44 12/17/07   2:04:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 Ifthe stators ofanexcited resolver, called the “transmitter,” are loaded with thestators ofasecond, called the” repeater” orthe” receiver,” (Fig. 13.6b) the latter will experience currents producing achanging Iilfany ofthese potentiometers areuseful ascontrol elements forpurposes other thm scanner-data transmission.. 488 THERECEIVING SYSTEM—INDICATORS [SEC. 
   2!$!2 2%#%)6%23   È°{x PROVIDE THE DESIRED STOPBAND REJECTION RESPONSE 4HE  KTH ORDER #)# FILTER FOR DECIMA 
 BASED TECHNIQUES ARE APPLICABLE TO THE ALONG 
 ÓÈ°ÓÈ  2!$!2 (!.$"//+  &OR RADAR ENGINEERS  A DISPLAY SUCH AS THAT SHOWN IN &IGURE  WILL MOST LIKELY  NOT BE VERY USEFUL SINCE PROPAGATION FACTOR   &P  IS THE DESIRED QUANTITY FOR THE RADAR  RANGE EQUATION AND NOT THE PROPAGATION LOSS AS COMPUTED BY !0- (OWEVER  THERE IS A  SIMPLE RELATIONSHIP BETWEEN PROPAGATION LOSS AND PROPAGATION FACTOR 4HIS IS   &,,P 
 For those who are familiar with  radar, it can be considered a refresher. †  Microwaves are loosely defined as those frequencies where waveguides are used for transmission lines and where  cavities or distributed circuits are used for resonant circuits rather than lumped-constant components. Microwave  radars might be from about 400 MHz to about 40 GHz, but these limits are not rigid. 
 PLE  PARAMETERS FOR A 3!2 MIGHT BE  2    KM   K    M  AND  CR   CCR    M THEN   $2    M   CR  AND THE CONDITION IS NOT SATISFIED 4HUS   THE PROCESSOR MUST USUALLY  CORRECT FOR RANGE MIGRATION  (OWEVER  THIS IS TYPICALLY ACCOMPLISHED BY MODERN 3!2  PROCESSING METHODS &OR SPOTLIGHT 3!2  THE  POLAR FORMAT ALGORITHM  IS OFTEN USED  TO ACCOMPLISH THIS CORRECTION /THER 0ROCESSING &UNCTIONS  #URLANDER ET AL PROVIDE A DETAILED DISCUSSION OF  SEVERAL KEY OPTIONS FOR 3!2 PROCESSING BEYOND SIMPLE IMAGE FORMATION L #LUTTERLOCK #URLANDER ET AL  #HAPTER   REFERS TO THE USE OF INFORMATION IN THE  RECEIVED SIGNALS TO ASCERTAIN THE CENTER FREQUENCY OF THE ECHOES FROM THE GROUND  CLUTTER  AND COMPENSATE FOR SIDEWAYS DRIFT OF THE PLATFORM L !UTOFOCUS #URLANDER ET AL  #HAPTER   DESCRIBES THE USE OF INFORMATION IN THE  COMPLEX  IMAGE ITSELF TO ESTIMATE AND CORRECT PHASE ERRORS  AND THEN REPROCESS AND SHARPEN THE IMAGE SEE ALSO #ARRARA ET AL   L #ALIBRATION #URLANDER ET AL  #HAPTER   REFERS TO THE USE OF TARGETS OF KNOWN RADAR  CROSS SECTION 2#3  IN THE SCENE TO OBTAIN THE ABSOLUTE LEVEL OF 2#3 PER PIXEL AND THUS R     THE GROUND 2#3 PER UNIT AREA L 'EOLOCATION #URLANDER ET AL  #HAPTER   IS THE PROCESS OF DETERMINING THE ABSOLUTE  LATITUDE AND LONGITUDE OF PIXELS IN THE 3!2 IMAGE  TYPICALLY USING INFORMATION FROM THE '03. £Ç°£È  2!$!2 (!.$"//+  £Ç°ÈÊ -,Ê  
  AW A    4HE WAVELENGTH  K  IN THE MEDIUM IS IN METERS    LP   AV F    WHERE F IS FREQUENCY IN (ERTZ 4HE  LOSSES IN SUCH SYSTEMS ARE DESCRIBED IN TERMS OF TANGENTS OF LOSS ANGLES   C   BETWEEN ELECTRIC AND MAGNETIC FIELDS 4HE ELECTRICAL LOSS TANGENT IS GIVEN BY TANDE ES WEE `` ` `  WHICH CAN BE SIMPLIFIED TO  TANDS WEEy` FOR LOW LOSS MATERIALS           REPRESENTING THE SUM OF THE CHARGE TRANSPORT AND POLARIZATION RELAXATION LOSSES  AND THE  PHASE ANGLE BETWEEN ELECTRIC FIELD AND CURRENT DENSITY 4HE SKIN DEPTH OR ATTENUATION LENGTH IS  @ ;M= THE DISTANCE ELECTROMAGNETIC ENERGY TRAVELS WHILE BEING ATTENUATED  BY E IN AMPLITUDE 4HIS DISTANCE IS KNOWN AS THE SKIN DEPTH   D  AND PROVIDES AN INITIAL  GUIDE TO THE USEFUL PENETRATION DEPTH OF A '02 SYSTEM ALTHOUGH IN SOME MEDIA THE USEFUL RANGE MAY BE GREATER 4HE INDIVIDUAL PROPAGATION CONSTANTS CAN BE WRITTEN AS   AWMEE EWMEE ` `` `¤ ¦¥³ µ´ 
 P. Mahoney, P. G. 
 J. Slobodnik, Jr., “Surface acoustic waves and SAW materials,” Proc. IEEE , vol. 
 Actually, nosharp distinction between trapping and standard propa- gation can bedrawn. Even our naive model suggests this; forweneed. 58 THERADAR EQUATION [SEC. 
 Cochran, B. Moran, and L. White (eds.), New York: Elsevier, 2001, pp. 
 A frequency-scan radar can radiate undesirable grating lobes, .just as citn any other array,  if rhc: electrical spacing between elements is too large. From Eq. (8.10h), the relationship  between the angle 0, at which the first grating lobe appears, and the angle O,, to which th: main  beam is steered, is given by  Isin 0, - sin 0,) = Alri (8.20)  If we assume that the grating lobe can be tolerated if it is located at 90°, then  I 1 + sin Ool I A/d (8.2 1 )  The limiting scan angle for the appearance of grating lobes is shown by the dashed curves in  Fig. 
 Likewise, a transmitting point source on the surface of the sphere is converted to  a plane wave on passing through the lens (Fig. 7.21). Because of the spherical symmetry of the  lens, the focusing property does not depend upon the direction of the incident wave. 
 Developed for the U.S. Marine Corps, it is unique among air surveillance radars in that it was the first to employ an all-solid-state transmitter. The solid-state transmitter of this radar is distributed over the antenna aperture in the form of individual row trans- mitter units. 
 Next, to Dr. Fred Harris of San Diego  State University and Mr. Richard Lyons, who graciously reviewed sections of the  chapter and offered several suggestions, all of which were incorporated. 
 BAND PERFORMANCE  OR REDUCED 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 8.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 Unequal Transmit and Reference Waveform Slopes. 
 TABLE 20.3  Nominal or Claimed Maximum Detection Ranges (kilometers) of Some HFSWR  Systems   (SeaSonde is a compact low-power radar designed primarily for remote sensing; it is available with  an upgraded performance option. The other radars shown were designed for surveillance. In all  cases, performance may fall far short of the cited values under inclement environmental conditions.) TARGET TYPE SWR 503    Raytheon   CanadaHFSWR BAE Systems   UKSECAR    Daronmont   AustraliaPodsolnukh-E    Niidar RussiaSeaSonde    Codar US Frigate 520 > 200 > 400 260 190 Offshore trawler 450   85 > 250 180 120 Small fishing boat   120  65 Go-fast speed boat    70  35  Rigid inflatable boat   22 Low-flying fighter- sized aircraft  75 > 200 ch20.indd   70 12/20/07   1:17:12 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 MENT  BUT COMPLICATES AN OTHERWISE WELL 
 Hildebrand and R. H. Sekhon, “Objective determination of the noise level in doppler   spectra,” J. 
 Ci, a2 - principal radii of surface curvature in orthogonal planes. 6. C — edge length. 
 TIME ADAPTIVE PRO 
 By making the angular location of the first  grating lobe coincide with the first null of the el~ment pattern (that of the real antenna),  grating lobes can be attenuated to a small value. The position of the first grating-lobe maxi­ mum of the synthetic array is  (J = J_ = ).jp  (i 2de 2v (14.7)  where de = v/fp = spacing between elements of the synthetic array  v = velocity of vehicle carrying the radar  fp = pulse repetition frequency  The position of the first null of the real antenna is approximately On= J./D, where D width of  the antenna. Since Og must be greater than or equal to On to avoid grating lobes, the following  condition is obtained  (14.8)  The right-hand portion of the equation applies for a focused SAR, since be, D/2. 
 If tlie resoltl-  tion of the radar is great enough to resolve the areas of lower clutter from thc areas of greater  cli~tter, targets within the clear areas can often be detected and tracked cvcn tliot~gl~ it nligllt t~c  predicted on the basis of the average clutter ao that it would not be possible.  The ability of some radars to resolve the strong clutter regions into discrete areas, be-  tween which targets may be detected, is called irltc.rcl~lrtc~r 111sihiliry. It is dil'fici~lt to esti~t~l~st~ a  quantitative measure of this effect; but it has been suggestedJ2 that (he irnprovernent in target  detectability can be approximated by the ratio of the average clutter level to the median  clutter, which can be as much as 20 dB for a medium-resolution radar (for example,hJ one with  a 2 11s pulse width and a 1.5" beamwidth). 
 Equation (12.16) applies to an ideal antenna with no sidelobes. In a practical antenna the  noise which appears at the antenna terminals enters via the sidelobe radiation as well as from  the main beam. In many cases the total noise power due to the sidelobes can be greater than  the noise power in the main beam. 
 This photograph shows theinstallation asdesigned foruseinTBM-3 aircraft, using anauxiliary gear box toobtain dual output from the TBM-3’s single engine pad. This expedient isusually much more successful than attempting toconvert (with low efficiency) direct current tolarge “bites” ofalternating current. When pressed foroutput mounting-pad space itiswell toconsider such “dual outlet” gear boxes. 
 294 297.  43. Rigden. 
 (a) R.3084, with additional sockets for recorder facilities and front panel access points for IF tuning; (b) R3039A [ 7].Airborne Maritime Surveillance Radar, Volume 1 2-13. selectable by the operator. An engraved Perspex scale of miles was inserted in front of the display. 
 TIME OBSERVATIONS v  )%%% 4RANS )NFORMATION 4HEORY  VOL )4 
 Thefrequency-response function, denotedH(f),expresses therelativeamplitude and phaseoftheoutputofanetwork withrespecttotheinputwhentheinputisapuresinusoid. ThemagnitudeIH(f)Iofthefrequency-response function isthereceiveramplitude passband characteristic. Ifthebandwidth ofthereceiverpassband iswidecompared withthatoccupied bythesignalenergy,extraneous noiseisintroduced bytheexcessbandwidth whichlowersthe outputsignal-to-noise ratio.Ontheotherhand,ifthereceiverbandwidth isnarrower thanthe bandwidth occupied bythesignal,thenoiseenergyisreduced alongwithaconsiderable part ofthesignalenergy.Thenetresultisagainalowered signal-to-noise ratio.Thusthereisan optimum bandwidth atwhichthesignal-to-noise ratioisamaximum. 
 Ruze 7 3 has shown that the approximation to the antenna pattern derived on the basis of  the Fourier integral for continuous antennas (or the Fourier-series method for discrete arrays)  has the property that the mean-square deviation between the desired and the approximate  patterns is a minimum. lt is in this sense (least mean square) that the Fourier method is  optimum. The larger the aperture (or the greater the number of elements in the array), the  better will be the approximation. 
 Inorder tominimize the required i-fbandwidth inthe receiver, the discriminator was setonone side ofthe pass band ofthe receiver. Avalue of1131c/sec was then chosen forthei-fbandwidth toprovide amargin totake care ofimproper tuning. The equipment isshown schematically inFig. 
 Insteadofmaintaining thefrequency excursion 4fconstant andobtaining avarying beatfrequency,4fcanbevariedtomaintain theheat frequency constant. Thebeat-frequency amplifier needonlybewidecnough topassthe received signalenergy,thusreducing theamountofnoisewithwhichthesignalmustcompdC. Thefrequency excursion ismaintained byaservomechanism tothatvaluewhichpermitsthe beatfrequency tofallwithinthepassband ofthenarrowfilter.Thevalueofthefrequency excursion isthenameasure ofthealtitudeandmaybesubstituted intoEq.(3.11). 
 OF 
 BEAM CLUTTER IS  .#. !$ AMPD" D#%),;FLUCT?MARGIN= q ;    =MAX " " QUANTALOG NOISE §©¶¸§ ©¨ ¨¶ ¸· ·;=    . 
 If the prf is ~nadc too higli, tlie likeliliood of obtaining target echoes from  tlic WI-orig piilse 11 arisrnissiori is increased. Eclio sig~ials received after an interval exceeding the  pulse-reyjctition period are called rr~~rltij,le-tin~e-arortnd echoes. They can result in erroneous or  corlftisillg range r~le:tsi~r-e~nents. 
 At100Me/see, diffraction minima occur only atshort ranges where thesignal strength ishigh, and they are much less pronounced than those athigher frequencies, as. SEC.17.16] RELAY SYSTEM FORAIRBORNE RADAR 735 indicated byFig. 17”15. 
 ch14.indd   19 12/17/07   2:47:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 
 Equipment of this kind is called instrumentation Radar.  The Fourier transform of the  signals, received in the frequency range,  into the time domain corresponds to a pulse response  with a resolution corresponding to the measuring bandwidth. This procedure is related to pulse  compression. 
 However, low-noise receivers are  sometimes accompanied by other less desirable properties that tend to result in a compromise  in receiver performance. Thus a low-noise receiver might not always be the obvious selection,  if properties other than sensitivity are important.  9.5 DISPLAYS  The purpose of the display is to visually present in a form suitable for operator interpretation  and action the information contained in the radar echo signal. 
 Meyer, 0. P .. and H. 
 7.6, is a more popular model for antenna design than the analytical models of  Table 7.1.)  An examination of the information presented in this table reveals that the gain of the  uniform distribution is greater than the gain of any other distribution. It is shown by Silver1  that the uniform distribution is indeed the most efficient aperture distribution, that is, the one  which maximizes the antenna gain. Therefore the relative-gain column may be considered as  the efficiency of a particular aperture distribution as compared with the uniform, or most  efficient, aperture distribution. 
 For small errors, if the ratio of voltage  gains is (1 ± ∆) or if the phase references differ by ( p /2 ± ∆) radians, the ratio of the  spurious image at −wd to the desired output of wd is ∆/2 in voltage, ∆2/4 in power, or  20 (log ∆) −6 in decibels.   V j V E t j E tI Q d d + = + + = +   cos( ) ( ) sin( ) w w 1 12∆∆E Ee Eej t j td d w w−− ∆ 2 (6.29) V j V E t j E t EeI Q d d + = + + =   cos( ) s in( ) cos w w ∆∆ 2j j t j td dEew w +   − ++   −  ∆ ∆∆2 2 2sinπ        (6.30) Historically, I and Q phase and gain corrections have been performed using  adjustments in the analog signal paths, as shown in Figure 6.13. Gain errors may  be corrected by a change in gain in the IF or video stages of either or both I and Q  channels. 
 Tabeling: Tracking lnstrumentati )n and Accuracy on the: Eastern Test  Range, IEEE Trans., vol. SET-11, pp. 14-23, March, 1965. 
 GROUND FUNCTIONS )T IS ALWAYS A MATTER OF OPINION WHAT THE MAJOR ADVANCES IN RADAR HAVE BEEN /THERS  MIGHT HAVE A DIFFERENT LIST .OT EVERY MAJOR RADAR ACCOMPLISHMENT HAS BEEN INCLUDED IN THIS LISTING )T COULD HAVE BEEN MUCH LONGER AND COULD HAVE  INCLUDED MULTIPLE EXAM 
 TION STATES 4HIS MULTIPLEXED TRANSMISSION SCHEME IMPLIES THAT THE RADARS 02& MUST BE  DOUBLED TO SATISFY THE MINIMUM .YQUIST SAMPLING RATE SIMULTANEOUSLY FOR EACH PAIR OF  TRANSMISSIONS $OUBLED 02& IMPLIES THAT THE AVERAGE RADIATED POWER MUST BE DOUBLED AND THE UNAMBIGUOUS RANGE SWATH IS HALVED  BOTH IN COMPARISON TO THE STANDARD CASE OF TRANSMITTING ONLY ONE POLARIZATION .OTE THAT THE AVERAGE DATA RATE IS THE SAME AS THE DUAL 
 Balfour, “Simulation of a phased-array antenna in a waveguide,” IEEE  Trans ., vol. AP-13, pp. 342–353, May 1965. 
 Therefore the dwell time in any direction is determined not by  the average nuniber of observations made by each sequential detector, but by that range  interval which requires the largest number of observations. This can result in relatively long  dwell times, and it is possible for the savings obtained with the Sequential Observer to be f negated. The required dwell time might be even longer than that of the fixed sample-number  Neyman-Pearson Observer. 
 V !A   B    ! C   D  
 DIMENSIONAL RADIATION PATTERN S ARE DERIVED AT MUL 
 S. Locke, Ref. 25.) The range and elevation lag errors may be similarly determined by calculation of derivatives of R(t) and <(>(/), respectively, and use of the constants for these tracking systems. 
 However, in this case reflected power from the antenna voltage-standing- wave ratio (VSWR) during transmit also is directed to the receiver, so a T/R tube and limiter are still required to protect the receiver during transmit. In either case, the duplexer accomplishes the objective of letting the transmit- ter and the receiver share a single antenna in pulsed radar systems. 4.2 MAGNETRON TRANSMITTERS Historically, the invention of the microwave magnetron during World War II made pulsed radar practical, and early radar systems were undoubtedly tailored around what magnetrons could do. 
 D. Lunden, and C. Chiou: Fenestrated Metal Radome, Microwaoe J., vol. 
 DETECTOR OUTPUT IS BIPOLAR VIDEO THAT  IS  IT IS A VIDEO PULSE WITH AN AMPLITUDE PROPORTIONAL TO THE ANGLE ERROR AND WHOSE POLARITY POSITIVE OR NEGATIVE  CORRESPONDS TO THE DIRECTION OF THE ERROR 4HIS VIDEO IS TYPICALLY PROCESSED BY A SAMPLE AND HOLD CIRCUIT THAT CHARGES A CAPACITOR TO THE PEAK VIDEO 
 WIDTH MODULATION 07-   PULSE 
  OR SHIPBOARD 
 R.M.:History oftheDirectional Antenna intheStandard Broadcast Bandforthe Purpose ofProtecting Service AreaofDistant Stations, IRETrailS.,vol.PGBTS-7, pp.5155. Februar)·. 1957. 
 lnterferometer.42 44 /\n interferometer consists of two individual antennas spaced so as to  obtain a narrow heamwidth for accurate angle measurement. The phase difference between the  signals of the two antenna elements ol the interferometer provides the elevation angle, as given  by 1:q. (5~·1 ). 
 M DIPOLE ANTENNA HAS A FREQUENCY 
 Hence the phase shifter in a series-fed array must be of lower  loss compared with that in a parallel-fed array. If the series pJ1ase shifters are too lossy,  amplifiers can be inserted in each element to compensate for the signal attenuation.  Since each phase shifter in the series-fed linear array of Fig. 
 The most straightforward approach is to  simply perform a complex multiply, as shown in Figure 25.26. In this example, the  complex input sample is denoted as A + jB, which is multiplied by the complex coef - ficient C + jD to produce (AC – BD) + j(AD + BC) in order to effect the phase shift.  This operation requires four multipliers and two adders. 
 Ilicks. :tnd F. H. 
 M.: "lz Proshlovo Radiolokatzii" (Out of the Past of Radar), Military Publisher of the  Ministry of Defense, USSR, Moscow, 1969.  15. IEEE Standard Letter Designations for Radar-Frequency Bands, IEEE Std 521-1976, Nov. 
 Since sea clutter is generally viewed as a surface-distributed process, the basic clutter  parameter is taken to be the normalized radar cross section (NRCS), s  0, of the surface,  commonly referred to as sigma zero  and expressed in decibels relative to 1 m2/m2. It is  obtained experimentally by dividing the measured radar cross section of an illuminated  patch of the surface by a normalizing area, so differences in the definition of this area  can lead to inconsistencies among various reports of NRCS measurements. Scattering  from any distributed target involves the product of the transmitting and receiving sys - tem footprints integrated over the target. 
 The latter are dominated by the  silicon carbide (SiC) MESFET and the gallium nitride (AlGaN/GaN) heterojunction  field effect transistor (HFET). The advent of the third semiconductor generation opens  enormous new possibilities in the area of high power amplifiers for use in solid-state.  The WBGS materials are able to produce very high power-output levels (5–20 w/mm) FIGURE 11.10  Typical two-stage GaAs MMIC power amplifier with insert  showing multiple paralleled gate fingers in final stage unit cell ( Photograph  courtesy of Raytheon Company ) ch11.indd   15 12/17/07   2:25:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Mc{jraw-llill Book Company, New York. 1951.  29. 
 In most cases of practical  interest the expected range of doppler frequencies will be much wider than the frequency  spectrum occupied by the signal energy. Consequently, the use of a wideband amplifier cover­ ing the expected dopplcr range will result in an increase in noise and a lowering of the receiver  sensitivity. If the frequency of the doppler-shifted echo signal were known beforehand, a  narrowband filter-one just wide enough to reduce the excess noise without eliminating a  significant amount of signal energy-might be used. 
  AND %23 
 Pmc. IfE.pIC.vol.104.pp.4.15.1.1.19·147.Mar..1957. J(lBlah.L.V.:Machinc Plotting orRadio/Radar Vertical-Plane Coverage Diagrams. 
 At the IF output the signals are hard-limited and separated by three narrowband filters. The signals are then converted to the same frequency(b) FIG. 18.18 («) RF phase-comparison mono- pulse system with sum and difference outputs. 
 L. Herr and J. Williams (eds.), November 21,  1986, pp. 
 This type of early SAR is described by Cutrona2 as follows: “The  coherent signals received at the synthetic array points are integrated, with no attempt  made to shift the phases of the signals before integration. This lack of phase adjust - ment imposes a maximum upon the synthetic antenna length that can be generated.  This maximum synthetic antenna length occurs at a given range when the round-trip  distance from a radar target to the center of the synthetic array differs by l /4 from the  round-trip distance between the radar target and the extremities of the array.” Cutrona  shows that the crossrange resolution is approximately ½ ( l R) ½.2 Unfocused SAR is typically not used today and is included here only for historical  reasons. 
 9.33, consists ofa15-ft coaxial line whose outer conductor ispierced with radiating slots spaced atintervals of2*in., which isless than the wavelength. The inner conductor consists ofa ~-in. shaft onwhich aremany ~-in. 
 VIDUAL ARRAY FEEDS 3OME OTHER NOTABLE FEATURES OF THE '2!30 CODE INCLUDE SCATTERING MODELS FOR MESH  FREQUENCY SELECTIVE OR LOSSY REFLECTOR SURFACES  AND A SPHERICAL WAVE EXPANSION 37%  FEATURE FOR MODELING OF SYSTEMS WHEREIN THE REFLECTOR OR SCATTERER IS IN THE NEAR FIELD OF THE FEED SOURCE &INALLY  THERE ARE VARIOUS OTHER ANTENNA SOFTWARE MODULES AVAILABLE FROM 4)#2! THAT CAN BE USED IN CONJUNCTION WITH '2!30 /NE NOTABLE EXAMPLE IS 0HYSICAL /PTICS 3HAPER 0/3   AN OPTIMIZER MODULE FOR SHAPED REFLECTOR SYNTHESIS ANDOR FEED ARRAY AMPLITUDEPHASE WEIGHT SYNTHESIS -ORE INFORMA 
 Asatisfactory operating level forthe AFC crystal is0.5 mw c-w power from thelocal oscillator and 1to2mwpulse powerfromthemag- netron. Reduction ofthemagnetron power level by65to90dbbelow thetransmitted power isobtained byacombination ofweak coupling out ofthe main r-fline and anattenuator, preferably dissipative. Itis important that ther-fsystem betight inorder toprevent leakage power, possibly many times that desired, from reaching the crystal bystray paths. 
 K. Moore, and B. D. 
 730–740, 1967. 169. P. 
 Malech: Radiating Elements and Mutual Coupling," Microwave Scanning  Antennas, vol. II," R. C. 
 Large deviations oftheoscil- lator areeasily accomplished, and there arenoproblems ofr-fbandwidth. Since the required video bandwidth was about 1.5 Me/see, atotal deviation of6Jfc/sec was chosen. The total frequency spectrum involved isthen alittle more than 9hlc/sec. 
 42, pp. 1033–1046, 2004. 121. 
 Inaddition two separate servoamplifiers and follow-up channels arerequired, one forthe roll-error component and one forthe pitch-error component. Although this provides complete stabilization, theweight ofthecomponents usually appears excessive sothat another type ispreferable. The roll stabilization referred toisstable-base stabilization with the pitch channel removed. 
 ITER SERVED THE PURPOSE OF DELIBERATELY RESTRICTING THE DYNAMIC RANGE TO REDUCE CLUTTER RESIDUES AT THE -4) OUTPUT 4HE RECEIVED SIGNALS ARE THEN CONVERTED INTO IN 
 18oftheRadia- tion Laboratory Series fordetails. Inorder topreserve good response tolong pulses, itisnecessary that thetime constant ofthecoupling circuit, C,(RL+R.),bekept large com- pared totheduration ofthelongest blocks ofsignals involved. Inthis event, thefractional amount ofdroop onthetop ofthelong pulse isjust theratio ofthepulse length tothecoupling time constant. 
 3–29, 1991. 82. C. 
 Some ferrite phase shifters operate over two octaves,29 and digital diode phase shifters that switch line lengths may function over even wider bands. The high . end of the frequency band is limited by the physical size of the elements, which must be spaced close enough in the array to avoid the generation of grating lobes. 
 TIONS 4HIS RATE  P 2  WAS INITIALLY IDENTIFIED BY *ACKSON AND SUBSEQUENTLY VERIFIED BY  -OYER AND -ORGAN   PA22C2 TAN      &OR OPERATION IN THE CO 
 Calculations are difficult because oflack of data, but experimentally avalue ofabout 30cpsatx=10cmisfound. Another and equivalent point ofview isthat when the plane isturning different parts have different doppler frequencies. Finally there is,inprinciple, alimit set bytarget acceleration. 
 NOISE RATIO 3.2  IN THE MAIN CHANNEL 4HE QUANTITY  "  IS THE RATIO OF   THE GUARD CHANNEL 3.2 TO THE MAIN CHANNEL 3.2 AND IS ILLUSTRATED IN &IGURE   4!",%  $ISCRETE #LUTTER -ODEL 2ADAR #ROSS 3ECTION M  $ENSITY PER SQUARE MILE    . 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 6.48  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 Direct Digital Synthesizer. 
 6.37  Surface Leakage  ...............................................  6.40  6.8 Mechanical Considerations  ....................................  6.40 6.9 Radomes  ................................................................ 
 Monopi~lse tracking radar can be  employed to avoid the vulnerability of conical-scan tracking radars to nlodulations that cause  it to break lock in angle.  Passive ECM. The noise jammer and the repeater jammer were examples of active 13CM. 
 C. Hansen, Phased Array Antennas , New York: John Wiley & Sons, 1998. 102. 
 The general processing problem encountered in dealing with GPR data is in the  widest sense the extraction of a localized wavelet function from a time series, which  displays very similar time-domain characteristics to the wavelet. This time series is  generated by signals from the ground and other reflecting surface, as well as internally  from the radar system. Unlike conventional radar systems in which the target can gen - erally be regarded as being in motion compared with the clutter, in the GPR case, the  target and the clutter are spatially fixed and the radar antenna is moved with respect  to the environment. 
 In principle, it is possible to determine the  trajectory of the target from dopplcr measurements only.57  Bistatic radar measurements. The measurements made with a bistatic radar are similar lo  those of the conventional monostatic radar except they are usually more complicated and  difficult to accomplish. The measurement of distance relative to one of the. 
 21.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 changes in the ground surface electrical parameters. Essentially the impedance of the  antenna is changed by its proximity to the ground; hence it cannot be considered to  have a stable impulse response. Any processing scheme that relies on invariant antenna parameters should take into  account the mode of operation of the antennas and the degree of stability that is prac - tically realizable. 
 IEEE T rans. Image Process. 2007 ,16, 2309–2321. 
 I). R.: "Syntllcsis of Planar Antenna Sources," Oxford University Press. London, 1974. 
 3.17  Clutter Map Automatic Gain Control  ...................  3.18  Automatic Noise-Level Control  ...........................  3.19  3.7 Filtering  ................................................................... 
 Brit. IRE. vol. 
 TION 4HE TOTAL REFLECTED ENERGY FROM THE MIRROR ROTATED BY  WILL EFFICIENTLY PASS THROUGH THE WIRE 
 CELLATION SPECIFICATIONS  WHICH IS WHY .EXRAD EMPLOYS A KLYSTRON )N THE PAST  SOME LONG 
 An ac- tive homing system is a self-contained radar which transmits its own radar energy at the target and tracks the target-reflected energy. The semiactive system in- cludes an external radar which illuminates the target while the missile receives and tracks the target-reflected energy to extract guidance information. The waveforms used vary from noncoherent pulse (used in some early sys- tems) to continuous wave (CW) and coherent pulse doppler (PD). 
 Altllough the pliase of the stalo influences the phase of the  transnlitted signal, any stalo phase shift is canceled on reception because the stalo that  generates the transniitted signal also acts as the local oscillator in the receiver. The reference  signal from the coho and the IF echo signal are both fed into a mixer called the pllase dctec-tor..  T11e phase detector differs frorn the normal amplitude detector since its output is proportional  to the phase difference between the two input signals. 
 4(% 
 If the target is in motion, R and the phase 4 are continually changing. A change  CHAPTER THREE CWANDFREQUENCY-MODULATED RADAR 3.tTHEDOPPLER EFFECf Aradardetectsthepresence ofobjectsandlocatestheirposition inspacebytransmitting electromagnetic energyandobserving thereturned echo.Apulseradartransmits arelatively shortburstofelectromagnetic energy,afterwhichthereceiver isturnedontolistenforthe echo.Theechonotonlyindicates thatatargetispresent,butthetimethatelapsesbetween the transmission ofthepulseandthereceiptoftheechoisameasure ofthedistance tothetarget. Separation oftheechosignalandthetransmitted signalismadeonthebasisofdilTerences ill time. 
 P. M. Woodward, A method of calculating the field over a planar aperture required to produce a  given polar diagram, J. 
 Random errorsinreflectors. The'classical workontheeffectsofrandom errorsonantenna radiation patterns isduetoRuze.73.99.101 Hepointedoutthatinareflector antenna, onlythe phaseerrorintheaperture distribution needbeconsidered. Suchaphaseerror,forexample, mightbecausedbyadeformation ofthesurfacefromitstruevalue.RuzelOIshowedinasimple derivation thatthegainofacircularaperture witharbitrary phaseerrorisapproximately ..,I (7.30). 
 The effect of some common nonthermal types of noise will be considered. Although it will not be feasible to consider all the possible types of radar situations, the methods to be described will indicate the general nature of the necessary procedures for environments and conditions not specifi- cally treated here. Some of the specialized types of radar, for which special anal- yses are required, are described in later chapters of this handbook. 
 0.2   0.5   1.1   1.7   2.2 0.60 .   0.2   0.5   1.0   1.2 0.65 .   0.2   0.7   1.0 0.70 . 
 Solid-state limiters. Solid-state PN and PIN diodes can be made to act as RF limiters and are  thus of interest as receiver prote~tors.~'-.~~ Ideally, a limiter passes low power without attenua-  tion, but above some threshold it provides attenuation of the signal so as to maintain the  output power constant. This property can be used for the protection of radar receivers in two  differentp implementations depending on whether the diodes are operated unbiased (self-  actuated) or with a d-c forward-bias current. 
 It can be seen that the targets both at the azimuth center and edges are well-focused, indicating that the EMAM method can estimate the spatial variance of the Doppler rate and the derivative of the Doppler rate well. The peak 60. Sensors 2019 ,19, 213 sidelobe ratios are about −13 dB, as shown in Table 4, indicating that the EMAM method has achieved higher estimation accuracy. 
 September, 1973. 20.Hsiao.J.K..andF.F.Kretschmer, Jr.:DesignofaStaggered-prf Moving TargetIndication Filter, TheRadioalldElectrollic Ellgineer, vol.43,pp.689-693, November. 1973. 
 This is the doppler angular frequency wd,  given by  . d</J 4n dR 4n:vr  rr)d = 2n/d = ·· · = ···· --= ---. de ,t dr ,t (3.1)  where fd = doppler frequency shift and llr = relative ( or radial) velocity of target with respect  to radar. 
 [ CrossRef ] 20. Berizzi, F.; Corsini, G. Autofocusing of inverse synthetic radar images using contrast optimization. 
 Moore and W. J. Pierson, “Measuring sea state and estimating surface winds from a polar  orbiting satellite,” in Proc. 
 For the rheological model, the variance of HP-deformation over all the interferograms was 1.6 mm, whereas that of the linear model was 2.4 mm, indicating an accuracy increase of 33% in the rheological model. 244. Sensors 2019 ,19, 3073 Figure 12. 
 ASV serviceability for January, February and March 1945 [ 1]. Type of ASVCoastal Command averages Hours per fault Sorties per fault Mk. IIIA, B, C 185.6 23.2 Mk. 
   PP n  .OVEMBER    '6 4RUNK AND 3 - "ROCKETT  h2ANGE AND VELOCITY AMBIGUITY RESOLUTION v IN  )%%% .ATIONAL  2ADAR #ONF  "OSTON    PP n  '6 4RUNK AND - +IM  h!MBIGUITY RESOLUTION OF MULTIPLE TARGETS USING PULSE 
 The phased array antenna has an aperture that is assembled from a great many similar radiating elements, such as slots or dipoles, each element being individually controlled in phase and amplitude. Accurately predictable radiation patterns and beam-pointing directions can be achieved. The general planar array characteristics are readily obtained from a few simple equations, given here but discussed later in greater detail. 
 The -46 dB sidelobe provides chaff rejection to ±16 percent. Because of the constraint of only 5 zeros available, this filter could not provide —46 dB rejection to ±20 percent. FIR RESPONSE RELATIVE DOPPLERSHIFTfT FIG. 
 There are two ba- sic radar modes: a passive mode in which the target is noncooperative, in that no cross-section augmentation is present, and an active mode in which the target has an on-board transponder. The radar operates out to 12 nmi in the passive mode and out to 300 nmi, with a +14 dBm transponder, in the active mode. Submodes include an automatic search and angle and range track capability and external an- gle control operation. 
 POLARIZATION &)'52%     %FFECT OF ANTENNA BEAMWIDTH ON  THE MEASURED SCATTERING COEFFICIENT AS A FUNCTION OF  ANGLE OF INCIDENCE. £È°Ón  2!$!2 (!.$"//+  3CATTERING  #OEFFICIENTS  FROM  )MAGES  2ADAR IMAGES PRODUCED BY REAL OR  SYNTHETIC APERTURE RADARS CAN BE USED FOR SCATTERING COEFFICIENT MEASUREMENT  5NFORTUNATELY  MOST SUCH SYSTEMS ARE UNCALIBRATED OR POORLY CALIBRATED  SO THE RESULTS ARE SOMEWHAT DUBIOUS  EVEN ON A RELATIVE BASIS  WHEN IMAGES ARE PRODUCED ON DIF 
 AMPLITUDE APPROXIMATIONS SEA WAVEHEIGHTS MUCH SMALLER THAN THE RADAR  WAVELENGTH  ARE USED  AB INITIO WITH 2AYLEIGHS HYPOTHESIS  IN WHICH THE SURFACE  BOUNDARY CONDITIONS ARE EMPLOYED TO MATCH AN ANGULAR SPECTRUM OF OUTGOING PLANE  WAVES TO THE INCIDENT FIELD n  ! GENERAL INTEGRAL FORMULATION BASED ON 'REENS THEOREM IS PURSUED EITHER IN A  SMALL 
 151,  pp. 19–30, February 2004. 133. 
 The type of  interaction is determined by tlie slow-wave circuit employed. A forward-wave interaction  takcs place when the pliase velocity and the group velocity of the propagating signal along tlie  slokv-kvave circuit are in the same direction. (The group velocity is the velocity with which  eriergy is propagated aloiig the slow-wave circuit, and the phase velocity is the velocity of the  RF signal on the slow-wave circuit as it appears to the electrons. 
 SHELF SOLUTION TO PRIMARY AIR 
 Integration before the detector is called pedetection, or coherent,  integration, while integration after the detector is called postdetection, or noncoherenr, integra-  tion. Predetection integration requires that the phase of the echo signal be preserved if full  benefit is to be obtained from the summing process. On the other hand, phase information is  destroyed by the second detector; hence postdetection integration is not concerned with  preserving RF phase. 
 HIGH 
 As the radar dwells in a particular direction, it is not looking elsewhere, where it is supposed to look. In addition, the burnthrough mode is not effective against chaff, decoys, repeaters, spoofers, and so on. More effective is the use of complex, variable, and dissimilar transmitted sig- nals which place a maximum burden on ESM and ECM. 
 Asatisfactory wave shape can beobtained with agaseous dis- charge switch ifatransmission line, either parallel wires orco- axial cable, isused instead ofthe con dens er.Consider anideal (lossless) line ofimpedance ZO=~, where Land Care the inductance and capacity per unit length, having aone-way transmission time 6.Elementary transmission-line theory shows that ifsuch aline, charged toa potential Vc,issuddenly con- nected across aresistance RL, there will result adiscontinuous current ofmagnitude z,~R~ flowing through the circuit foratime t,=2~,and the voltage appearing across theload (neglecting the small RL voltage drop across the switch) will begiven byVL = VC ZO+R.” Successive reflections will occur, theamplitude ofthenth reflection being given by v.” =VcZO?RL@~;~)”” The general wave shape obtained isshown inFig. 10”27 forthree values ofRJZ,. Ofcourse, ifR.=ZO,noreflections occur, and aperfect rectangular pulse isobtained. 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 the model states. The update equation for the ith model depends not only on the ith  model state but also on the states of all other models. 
 123. M. Migliaccio, “Sea wind field retrieval by means of microwave sensors: a review,” in Proc. 
 To illustrate this principle, if a ship’s whistle weresounded in the middle of the ocean, the sound waves would dissipate theirenergy as they traveled outward and at some point would disappear entirely.If, however the whistle sounded near an object such as a cliff some of theradiated sound waves would be reﬂected back to the ship as an echo. The form of electromagnetic signal radiated by the radar depends upon the type of information needed about the target. Radar, as designed formarine navigation applications, is pulse modulated. 
 An altimeter’s orbit must be chosen so that the tidal aliases do not  get confused with signals of geophysical interest. The T/P Orbit . The state-of-the-art (at least in accuracy and large-scale circulation  studies) is Jason-1, operating in the orbit originally designed for TOPEX/Poseidon. 
 An individual duplexer is  placed between each transmitter’s channelized output and its corresponding antenna  element. Provision could be included for electronic beam steering using high-power  phase shifters or transmit modules with low-power beam steering. On receive, each duplexer output is sent to its own digital receiver. 
 The transversal, or nonrecursive, filter of Fig. 4.11 can be designed to achieve filter  responses suitable for MT11-10 but a relatively large number of delay lines are needed for  filters with desirable characteristics. An N -1 delay-line canceler requires N pulses, which sets  a restriction on the radar's pulse repetition frequency, beamwidth, and antenna rotation rate,  or dwell time. 
 2.1, this problem has been analyzed by Swerling5 and others.6"10 Curves have been calculated that allow determining the appropriate value OfD0 for the fluctuating-signal case, for various probabilities of detection and false alarm (Sec. 2.4). Automatic Detection. 
 59-65, March, 1956.  14. Cady. 
 When m = l, the  chi-square distribution of Eq. (2.40) reduces to the exponential, or Rayleigh-power, distribu­ tion ofEq. (2.39a) that applies to Swerling cases 1 and 2. 
 The angle-error­ detector outputs are amp]ified and drive the antenna elevation and azimuth servo motors.  The angular position of the target may be determined from the elevation and azimuth of  the antenna axis. The position can be read out by means of standard angle transducers such as  synchros, potentiometers, or analog-to-digital-data converters. 
 Although ittendstocollectonmanytypesofstructures andcanobtainlarge thicknesses. boththeoryandex'periment showalackofrime-ice formation onaspherical radome.115Thetrajectories ofwaterdroplets intheairstre~mflowingaroundlargespheresdo notresultinmuchimpingement. Collection efficiencies mightbeonlyafewpercent. 
 (b) SSN = 100.Ground Range (nmi) (b)Ground Range (nmi) (o) . 24.77 RECEIVER-PROCESSOR The prediction method indicated above is based upon long-term medians of ver- tical soundings, measured path losses, and observed noise. The statistical distri- butions are for a particular hour over days of the month or season. 
 For HRWS, different linear-FM slopes are applied to looks 2 through m of a m-look  dwell, where m is typically 3. The PRF is high enough for at most only a doppler sign  ambiguity. Detections in looks 2 through m, must correlate in doppler with detections  in the first look, which has no slope. 
 Low-power grid-control tubes have been used in phased array radars at UHF and have  proven to be an economical and reliable source of power. In the AN/FPS-85 satellite­ surveillance radar built by Bendix Corporation for the U.S. Air Force, the transmit array con­ tains 5184 identical modules using the Eimac 4CPX250K ceramic tetrode.23 Each module has  a peak power or l Ok Wand is 7 by 9 by 31 inches with a weight ornearly 50 lb. 
 The detection of ships requires more sophis-  ticated processing since the relatively low velocity of ships produces doppler-frequeilcy strifts  comparable to those of the sea (which is also a moving target). Even thougli the radar cross  section of ships is often greater than that of aircraft, longer observation tinies are reqtiirccl to  provide sufficient resolution in doppler frequency.  Character of OTH radar. 
 Conf. Radar 2002 , Conf. Pub. 
 The name inverse  sc.attcri,tg5'%as been used to describe this method for obtaining the target size and shape, and  tllus provide a means for target classification. The use of high-range-resolution radar for  profiling a target, and tlie inverse synthetic aperture radar mentioned above are two practical  examples of target classification methods that might be called approximations of inverse  scattering.  Instead of examining the radar echo as a function of frequency, the target response to an  impulse can give the equivalent information since the Fourier transform of the impulse con-  tains all frequencies. 
 pp. 85 92, January. 1968. 
 IRE, vol. 36,  pp. 1289-1296, October, 1948. 
 MATELY ORTHOGONAL TO THE RADAR SIGNAL THAT THE 3!2 IS UTILIZING AT THE CURRENT 02)  AND THUS  A MATCHED FILTERING WITH THE CURRENT 02) RADAR SIGNAL WOULD WEAKEN THE $2&- REPEATER JAMMER SIGNAL )N 3OUMEKH  A NOVEL METHOD IS OUTLINED THAT  COMBINES THE ABOVE MENTIONED PULSE DIVERSITY RADAR SIGNALING WITH A NEW COHER 
 IMO now defines this process as Target Tracking (TT) , which includes target data  obtained from AIS. The basic requirement calls for a minimum radar tracking capac - ity of 20 targets on ships less than 500 gt; 30 targets on ships between 500 and  10,000 gt; and 40 targets on ships over 10,000 gt. In addition, ships over 10,000 gt  must have an automatic target acquisition capability. 
 TION LOSS CAN BE DESCRIBED WITH THE AID OF THE PROPAGATION FACT OR &   WHICH IS DEFINED  AS THE RATIO OF THE ACTUAL FIELD STRENGTH AT A POINT IN SPACE TO THE FIELD STRENGTH THAT WOULD EXIST AT THE SAME RANGE UNDER FREE 
 Effective Aperture. The aperture of an antenna is its physical area projected on a plane perpendicular to the main-beam direction. The concept of effective aperture is useful when considering the antenna in its receiving mode. 
   TRACKING LOOPS CONSTANT FOR STABLE AUTOMATIC ANGLE TRACKING 3OME MONOPULSE SYSTEMS  SUCH AS THE TWO 
 The ionosphere is only ~ 0.1% ionized at the altitudes of  interest to HF radar, but waves in the neutral gas, under the restoring force of gravity,  transfer their motion to the free electrons via collisions. As the distribution of electrons  defines the “reflecting surface” experienced by the radar signals, the apparent bearing  and range of the target will fluctuate as the ionospheric “reflecting surface” undulates  in response to the AGW. This undulation is known as a traveling ionospheric distur - bance (TID). 
 The other two FDP’s had British long-wave equipment. The longer range ofthe microwave radar shows inthelonger track duration fortheFDP equipped with that set. Differences inthetotal number oftracks reported arwe from adiffer- ingdensity ofairtraffic indifferent areas, and from thefact that thefrac- tion oftime spent offtheairformaintenance and other reasons differed from one FDP toanother. 
 11.9, There isnounique orgenerally accepted definition oftheimpedance ofawaveguide. This might beexpected from the lack ofdefinite localized terminals atwhich the voltage and current could, inprinciple atleast, bemeasured. Howe\-er, the usual procedures ofimpedance- matching arecarried over from transmission-line theory, and calculations are made onthe basis ofnormalized impedances. 
 3QUARED 
  !C   D   V !A  
 W.: Scale Model Development of a High Efficiency Dual Polarized Feed for the Arecibo  Spherical Reflector, IEEE Trans., vol. AP-21, pp. 628-639, September, 1973. 
 REPEAT ORBIT WAS REQUIRED 3INCE ITS PUBLIC RELEASE IN   THE DATA SET FROM THE FIRST   
 In the alternate 1-degree azimuth intervals another 10 pulses are transmitted at  a different prf to eliminate blind speeds and to unmask moving targets hidden by weather.  Changing the prf every 10 pulses, or every half beamwidth, eliminates second-time-around  clutter returns that would normally degrade an MTI with pulse-to-pulse variation of the prf.  A block diagram of the MTD processor is shown in Fig. 
 SUPPORT JAMMING IS THE GREATER %20 AVAILABLE FROM A COLLECTION OF PLATFORMS IN CONTRAST WITH A SINGLE PLATFORM (OWEVER  THE REAL VALUE OF MUTUAL 
 The entire radar system—transmitter, antenna, and operational parameters—must be  keyed to function as part of an MTI radar. For example, excellent MTI concepts will  not perform satisfactorily unless the radar local oscillator is extremely stable and the FIGURE  2.94 Performance of phase-difference doppler frequency estimator for different  weighting functions of the doppler filter bank10 20 30 40 50 60 70 80 90 100 Sidelobe  Level - SLL (dB)Cramer-Ra o boundUniform weightin gChebyshev weightin g Taylor weightin g( )2 1 1fk S nnσ= ⋅ ⋅− 10–1100101102Doppler Error Constant - k Cramer-Ra o boundUniform weightingCheb yshev weighting Taylor weightingk S1.n.(n2 – 1)σf= ch02.indd   91 12/20/07   1:48:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Experimental data show, however, that this  distribution does not apply with a high-resolution radar which illuminates only a small area  of the sea. The probability density furiction deviates from Rayleigh when the area illuminated  by the radar has a dimension (usually the dimension determined by the pulse width) which  is comparable to, or smaller than, the water wavelength.13 There does not seem to exist any  single analytical form of probability density function that fits all the observed data. The actual  form of the pdf will depend on the,size of the radar ,resolution cell and the sea state. 
 MENT IMPOSES A MAXIMUM UPON THE SYNTHETIC ANTENNA LENGTH THAT CAN BE GENERATED 4HIS MAXIMUM SYNTHETIC ANTENNA LENGTH OCCURS AT A GIVEN RANGE WHEN THE ROUND 
 THE ECHO COMES HOME 55  On land beacons, and with navigational systems such  as Gee, the aerials can be fixed, but with certain airborne  equipment, such as H2S, the rotation of the aerial to  scan and sweep the ground below, and thus to build up  a television picture by radar reflection, forms an integral  part of the system. One essential of nearly every radar  aerial array, however, is that it must have highly direc-  tional properties. The main object is to concentrate the  beam into as small a space as possible; in fact, the  shorter the wavelength we employ (the higher frequen-  cies) the more we approach the state of light, ideal for  many radar purposes, where the outgoing beam is vir-  tually only a pencil, a degree or two in width. 
 De Maio, A. Farina, and F. Gini, “Performance analysis of the sidelobe blanking system for  two fluctuating jammer models,” IEEE Trans ., vol. 
 1 and 15, 1946.  18. Katzin, M.: On the Mechanisms of Radar Sea Clutter, Proc. 
   -ARCH   * 7ARD  h3PACE TIME ADAPTIVE PROCESSING FOR AIRBORNE RADAR v -)4 ,INCOLN ,ABORATORY  4ECHNICAL 2EPORT   $ECEMBER     , % "RENNAN AND & - 3TAUDAHER  h3UBCLUTTER VISIBILITY DEMONSTRATION v 4ECHNICAL 2EPORT   2, 
 Alter: Automatic Detection and Integrated  Tracking. IEEE /975 lntcnwtivnal Radar Co11fi.•re11ce. pp. 
 Srivastava: Snow Size Spectra and Radar Reflectivity, J. Atmos. Sci., vol. 
             (b)  
  
 522-527, July, 1970.  66. Cantrell, B. 
 A negative value (in red color) indicates land subsidence, and a positive value (in blue color) indicates uplift. The total number of derived permanent scatter (PS) points was 8,680,765, and the average density was 3472 points/km2. The subsidence rate varies from −51.56 to 27.80 millimeters per year (mm/yr) with an average of −0.03 mm/yr. 
 NOLOGY  SUCH AS '.33  IS NOT ACCEPTABLE TO THE MARITIME COMMUNITY AND NEITHER TO AVIATION &OR INSTANCE  IT IS EASY TO JAM ALL '.33 USERS OVER A WIDE AREA BECAUSE OF THE SMALL AMPLITUDE OF THE RECEIVED SIGNAL 4HIS MEANS THAT RADAR AND OTHER POSITION 
 January.  1974.  1111:FI.ITTIWNICALI.Y STEERED PHASED ARRAY ANTENNA INRADAR341 102.Davies.D.E.N.:AFastElectronically Scanned RadarReceiving System,J.Brit. 
  IN SIDELOBES 4O EVALUATE THE EFFECT OF MAIN 
 This is called arc loss. Its magnitude depends upon the characteristics of the input window and  the gas used. The arc loss might be! to l dB in tubes filled with water vapor and 0.1 dB or less  with argon filling. 
 Zebker and R. Goldstein, “Topographic mapping from interferometric synthetic aperture radar  observations,” J. Geophys. 
 ORDER EQUIVALENT CURRENT AND  CORNER DIFFRACTION SCATTERING FROM FLAT PLATE STRUCTURES v  )%%% 4RANS  VOL !0 
 The maximum signal level relative to thermal noise that can be processed linearly is related to the number of amplitude bits in the A/D by £= = 20log(2^) ,„.,„ N \ noise / where 5max/N = maximum input level relative to noise, dB NAD = number of amplitude bits in the A/D noise = rms thermal-noise level at the A/D, quanta From the relationships described above and assuming that the A/D limits the dynamic range, the A/D size can now be determined. An additional factor, that of a margin to allow for main-beam clutter fluctuations above the rms value, also needs to be considered. Since main-beam clutter time fluctuation statistics are highly dependent on the type of clutter being observed, such as sea clutter or clutter from an urban area, and are generally unknown, a value of 10 to 12 dB above the rms value is often assumed for the maximum level. 
 andF.n.Ferrell:Ultra-short WavePropagation. I'roc.IRE.vol.21. pp42746).March.19)). 
 W. Haney, F. P. 
 TO 
 It acts as tlw collcrent  reference needed to detect the doppler frequency shift. By COIIC'~.LJII~ it is meant that the pliast: of  the transmitted signal is preserved in the reference signal. The reference signal is the distin-  guishing feature of coherent MTI radar. 
 ,Ê, 
   
 4.2.4 Receiver R3553 or R3554 This unit was a modi ﬁcation of R3515/6 used on ASV Mk. III, arranged to operate on an IF of 45 Mc/s instead of 13.5 Mc/s. The IF bandwidth was about 3.5 Mc/s.The unit could also be used for ASV Mk. 
  +1 
 Joint Sparsity Constraint Interferometric ISAR Imaging for 3-D Geometry of Near-Field Targets with Sub-Apertures. Sensors 2018 ,18, 3750. [ CrossRef ][PubMed ] 11. 
 GAUSSIAN CLUTTER 2ADAR 3CHEDULING AND #ONTROL  4HE INTERACTION OF THE RADAR 
 Compensation for clutter doppler spread. The simple expression of Eq. (4.36) shows that the  spread in the clutter spectrum is a function of the angle 6 between the velocity vector of the  moving platform and the antenna beam-pointing direction. 
 If a monostatic radar is located at the transmit site and a bistatic hitchhiker is  located at the receive site, both measuring target doppler, fM and fB, respectively, the  two measurements can be combined to estimate the target velocity vector ( V, d ) in the  bistatic plane. One such estimate is  d = tan−1{[ fM / fB sin(b /2)] − cot(b /2)} (23.10)  V = l fB / 2cosd = l fM  / 2cos(d − b /2) (23.11) where b is obtained by solving the bistatic triangle, for example, by using mono - static range, monostatic LOS, and an estimate of the baseline. A third hitchhiking  site allows the target velocity vector to be measured in three dimensions. 
 9.14), aradar intended fordetecting airplanes and determining their altitude, especially inmountainous terrain. Although 1War Department Technical Nfanual TM 11-1568.. SEC.9.12] EXAMPLES OFMECHANICAL SCANNERS 287 itmay bemounted and used ontwo trucks, this setismore commonly based ontheground. 
 ENT REFLECTING LAYERS  SO A SINGLE INTERFERENCE SOURCE IS OFTEN RECEIVED AS A NUMBER OF MULTIPATH COMPONENTS WITH DIFFERENT $O!S  BOTH IN ELEVATION DUE TO THE DIFFERENT HEIGHTS OF REFLECTION POINTS  AND IN AZIMUTH DUE TO LAYER 
 Symp. on  Phased-Array Systems and Technology 2003 , Boston (USA), October 14–17, 2003, pp. 1–8. 
 394-431. 12. Pitzalis, O., and R. 
 AXIS TRACKING  WAS DEVELOPED TO MINIMIZE  RADAR AXIS DEVIATION FROM THE TARGET BY PREDICTION AND OPTIMUM FILTERING WITHIN THE TRACKING LOOP   4HE TECHNIQUE IS PARTICULARLY EFFECTIVE WHEN THE TARGET TRAJECTORY IS  KNOWN APPROXIMATELY  SUCH AS WHEN TRACKING SATELLITES IN ORBIT OR A BALLISTIC TARGET ! COMPUTER IN THE TRACKING LOOP CAN CAUSE THE RADAR TO FOLLOW AN ESTIMATED SET OF ORBITAL PARAMETERS  FOR EXAMPLE )T ALSO PERFORMS OPTIMUM FILTERING OF RADAR ANGLE 
 BANDWIDTH PRODUCT EQUAL TO 4"     4HE ,&-  SLOPE IS "4    -(Z§S 4HE INSTANTANEOUS FREQUENCY OF THE ,&- WAVEFORM VARIES  BETWEEN  AND  -(Z OVER THE PULSE DURATION  AS INDICATED BY THE REDUCTION IN THE  SPACING OF SUCCESSIVE POSITIVE 
 A waveguide isanexample ofadispersive line.Thevelocity vs.frequency characteristic ofsuch transmission linescanbeusedtoadvantage toprovide' morefrequency sensitivity; thatis,a smaller wrap-up factorcanbeobtained foragivenscanangleandfrequency excursion. Asketchofafoldedwaveguide forexciting anarrayofslottedwaveguides isshownin rig.8.16.Thistypeoffeedisknownasasnakefeed,serpentine, orsinuous feed.Other slow-wave transmission linescanbeusedforthefeed,including helicalwaveguide69•70and corrugated waveguide.71Theconfiguration ofFig.8.16canbeusedtoscanapencilbeamin elevation, withmechanical rotation providing theazimuth scan.TheAN/SPS-48, Fig.8.17.is suchanexample. Itisafrequency-scan radarusedonmanyU.S.Navyshipsforthe {lleaSUrement oftheelevation andazimuth ofaircrafttargets.Itissometimes calleda3Dradar. 
 I I I I--/----+ \ I \ I \ I \ I---...--\I----~ ----~FeedFigure7.10Parabolic rellectorwithoffsetfeed.. may permit energy to leak through, with the result that the backlobe will increase and the  antenna gain decrease.  Solid sheet surfaces may be of either aluminum or steel.ls-l6 Steel is a popular choice,  particularly where weight is not a controlling factor. 
 269–278, 1971. 87. D. 
 The factor CB has been named the band- width correction factor because it was originally defined in terms of bandwidth op- timization, but in actuality it is a filter mismatch factor, in the North matched-filter sense. As Eq. (2.8) implies, CB^\. 
 R. M. Lhermitte and D. 
 Modes 0+ 1− 1+Meteor trails Ionosphere Radar FIGURE 20.15  Meteor trail specular scattering geometry for several propaga - tion modes FIGURE 20.16  Predicted range dependence of meteor echo strength compared with measurements; ground  clutter returns are also shown. The distribution of meteor radiants determines this variation. Predicted ver sus measured c lutter distrib utions 30 20 10Echo power (dB)0 −20 −30−10Surface bac kscatter Mode 0+ 400 600 800 1000 1200 1400 Range (km)1600 1800 2000 2200 2400Mode 1+ Mode 1−Meteor bac kscatter1985 da y 293  0130 local time frequency 6.8 MHz ch20.indd   39 12/20/07   1:16:50 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 VERSUS 
 STATE TRANSMITTERS REQUIRE THE USE OF LONG PULSES 4HE  !32 
 Each beam  to be formed requires one additional phase shifter, as shown in Fig. 8.25. The simple array in  this figure is shown with but three elements, each with three sets of phase shifters. 
 M. Skolnik, “A long range radar warning system for the detection of intercontinental ballistic  missiles,” MIT Lincoln Laboratory TR 128, August 15, 1956. 34. 
 The passive diode-limiter also finds important application when used with  a radioactive-primed gas tube TR. The combination is known as a passiile TR-limiter. The  passive TR-limiter protects the receiver from nearby transmissions even when the iadar is shut  off since it requires no active voltages for either the radioactive-primed TR tube or the diode  limiter. 
 Thus, the low ERP of these transmitters constrained by the available  bandwidth conspire to significantly reduce their utility for PBR surveillance. The type of modulation used by a broadcast transmitter is particularly important. For  example, the 1985 Crystal Palace TV transmitter trials in London122 attempted range  measurements with analog TV waveforms but found that they generated high range side-   lobes (~5 dB), range ambiguities every 9.6 km, and modest range resolution (~4 km),  and concluded that such waveforms were more suitable for doppler measurements. 
 CHAFF TECHNIQUE AVAILABLE TO RADAR  IS THE USE OF DOPPLER FILTERING  WHICH EXPLOITS THE DIFFERENT MOTION CHARACTERISTICS OF THE TARGET AND THE CHAFF  4HE CHARACTERISTICS OF CHAFF ARE SIMILAR TO THOSE OF WEATHER CLUTTER   EXCEPT THAT THE CHAFF 
 4. Bonner, H. M.: The Radio Proximity Fuse, Elec. 
 Precipitation Clutter.  It is well known that circular polarization (CP) can be a  counter to rain clutter because its reflection is predominately cross-polarized to inci - dent circular polarization. However, very few shipborne navigational radars use CP,  even though 10–20 dB improvement in rain clutter rejection is typically achieved  from its application. 
 2446 \11._...:........; 20~\t :t-l-i'36653----.l.....1.,.--1.449_~ _.~--._- c----.:.'25/'__ _2.0'RANGE(YARDS) ,21727 ,.,Ii . "26680 '31 684 (! 4183/' I. I46972, TRACKTIME(MINUTES) --I CMFigure5.16Example ofthemeasured elevation trackingerrorusingaphased-array radarwith2._rbeamwidth. 
 Amer. Meteoro.  Soc., vol. 
 (2.15). ever, on the basis of experiments at the Massachusetts Institute of Technology (MIT) Radiation Laboratory conducted somewhat later (also with rectangular pulses), it was concluded (Ref. 16, p. 
 TION v IN !DVANCES IN .EURAL )NFORMATION 0ROCESSING 3YSTEMS   #AMBRIDGE -)4 0RESS     PP n  ' ! 7ATSON AND 7 $ "LAIR  h)-- ALGORITHM FOR TRACKING TARGETS THAT MANEUVER THROUGH COORDI 
 Kitaigordskii,” J. Geophys. Res., vol. 
 11.12. The second modulation might be a  linear frequency modulation which increases, rather than decreases, in frequency. This is  analogous to the FM-CW radar of Chap. 
 TIME !DAPTIVE 0ROCESSING  2 + +LEMM ED   ,ONDON 3PRINGER     PP n  9 ) !BRAMOVICH  3 * !NDERSON  ! 9 'OROKHOV  AND . +  3PENCER  h3TOCHASTIC CONSTRAINTS  METHOD IN NONSTATIONARY HOT CLUTTER CANCELLATION  PART ) &UNDAMENTALS AND SUPERVISED TRAINING APPLICATIONS v )%%% 4RANS !%3  VOL   PP n  /CTOBER   9 ) !BRAMOVICH  3 *  !NDERSON  AND . +  3PENCER  h3TOCHASTIC 
 Definitions. The reader is cautioned that there are no universally accepted definitions of the terms pulse duration and spectral bandwidth of the transmitted signal, impulse response and bandwidth of filters, or the equivalent antenna parameters, beamwidth and spectral bandwidth caused by scanning. These terms should always be used with clarifying adjectives to define their meaning. 
 Thus thetwo devices together “resolve” the original voltage interms ofthe difference ofthetwo angles. Aresolver with a multiple-phase rotor isknown asa“differential” synchro orresolver. Itisused inreducing data from relative totrue bearing (one synchro r--lStstor (a) IKV sin(@92) 1 =01 v KV Sintll /10, L_- - 1 I (b) KV COS (61-82) * FIG.13.6.—Two-phase synchros. 
 _ 01/XP j 2rr .,l sin q> dz  N,.Jrmalizing to make E(O) A~_~i~J1_ti~l.,ll_~in ~J = Aoa [sin n(a/.,l) sin 4>]  (rr/l) sin tp n(a/,1.) sin q>  results in A0 = 1/a; therefore  E(q,) = sin [n(a/.,l) sin 4>]  n:(a/,l) sin tp (7.15)  (7.16)  This pattern, which is of the form (sin x)/x, is shown by the solid curve in Fig. 7.3. The  intensity of the first side lobe is 13.2 dB below that of the peak. 
 340–355. 13. R. 
 TIME ANTI 
 The objective of decoys is to cause a dilution of the assets of the defensive system, thereby increasing the survivability of the penetrating aircraft. The other major type of active jammer is deceptive ECM (DECM). Deception is the intentional and deliberate transmission or retransmission of amplitude, fre- quency, phase, or otherwise modulated intermittent or continuous-wave (CW) signals for the purpose of misleading in the interpretation or use of information by electronic systems.8 The categories of deception are manipulative and imitative. 
 80.Offutt,W.B.:AReviewofCircular Polarization asaMeansofPrecipitat ionClutterSuppression and Examples, Proc.Natl.Electronics Conf(Chicago), vol.II,pp.94-100,1955. HI.Hendry, A.•andG.C.McCormick: Deterioration ofCircular-polarization ClutterCancellation in Anisotropic Precipitation Media,Electronics Letters,vol.10,no.10,pp.165-166, May16,1974. 82.Nathanson, F.E.:Adaptive Circular Polarization, IEEE1975International RadarCon./i.·rt'nct.', Apr. 
 2017 ,52, 2016RS006116. [ CrossRef ] 20. Li, L.; Zhang, Y.; Dong, Z.; Liang, D. 
 This technique is most accurate if the wind field is uniform in  the region scanned by the radar. The method depends upon an analysis of the radial  velocity measured during a complete scan in azimuth with a single fixed elevation  angle. At any slant range r, the height of the measurement is r sin a and the radius of  the region scanned is r cos a, where a is the elevation angle as depicted in Figure 19.8. 
 Scanning may also be accomplished by arranging a series of feeds on the locus of the focal  points of the torus and switching the transmitter power from one feed to the next with an  organ-pipe scanner.128·129 The principle of the organ-pipe scanner is shown in Fig. 7.17. The  transmission lines from the feeds are arranged to terminate on the periphery of a circle. 
 The IC values of the proposed method results are quite larger than the other results, particularly for spaceborne sub-images. T able 2. The entropies of six sub-images. 
 THERADAR EQUATION 65 precision intheindividual parameters oftheradarequation. Nevertheless, ira.particular range isrequired ofaradar,thesystems engineer mustprovide it.Thesafestmeanstoachieving a specified rangeperformance istodesignconservatively andaddasafetyfactor.Theinclusion ofasafetyfactorindesignisnotalwaysappreciated, especially incompetitive procurements, butitisastandard procedure inmanyotherengineering disciplines. Inthefewcaseswherethis luxurywasrcrmitted, fineradarswereobtained sincetheyaccomplished whatwasneeded cvcnunderdcgradlxl conditions. 
 MEDIATE FREQUENCY OF  -(Z $ETECTION AND 0ROCESSING  !FTER THE ,.&%  A LOGARITHMIC AMPLIFIER REDUCES THE  DYNAMIC RANGE OF THE RECEIVED SIGNAL TO PREVENT LIMITING ! DYNAMIC RANGE OF AROUND  D" IS TYPICALLY ACHIEVED IN PERHAPS AN EIGHT 
 122. S. J. 
 CILE ANY MULTIPLE TRACKS AS WELL AS PERFORM THE REGISTRATION !LTERNATIVELY  THE PROBLEM OF TARGET TRACKING CAN BE INTEGRATED WITH THE PROBLEM OF DETERMINING THE IONOSPHERIC PROPAGATION PATHS "Y AUGMENTING THE STATE VECTOR USED FOR REPRESENTING A TARGET WITH ADDITIONAL PARAMETERS THAT CHARACTERIZE THE PROPAGATION PATH STRUCTURE  A JOINT ESTIMA 
 The statistical nature of these several  parameters does not allow the maximum radar range to be described by a single number. Its  specification must include a statement of the probability that the radar will detect a certain  type of target at a particular range.  In this chapter, the simple radar equation will be extended to include most of the impor­ tant factors that influence radar range performance. 
 A. Price, Instruments of Darkness: The History of Electronic Warfare , New York: Charles  Scribner’s Sons, 1978. 55. 
 This process yields  the set of resultant signals Rij, where the subscript i denotes the pulse pair and the  subscript j denotes the component of the pair. Because h1 does not equal h2, dif- ferent weighting constants are required for each pulse pair. The values of k1 for the  quadrature correction of the first pulse pair, k2 for the quadrature correction for   the second pulse pair, l1 for the in-phase correction for the first pulse pair, and l2  for the second pulse pair are optimized by minimizing the integrated residue power  over the significant portion of the antenna pattern, usually chosen between the first  nulls of the main beam. 
 In contrast to a monostatic radar, however,  propagation effects can be significantly different over the two bistatic paths and must  be treated separately. Multipath is the primary example, where the target can be in a  multipath lobe on one path and a multipath null on the other, depending on antenna  and target altitude and terrain conditions. When a correlation receiver uses the demodulated direct path RF signal as its refer - ence, that signal is subjected to interference (multipath and RFI), which is different  from interference affecting the target echo path. 
 STATE  DEVICES  IT IS ESPECIALLY TEMPTING TO AVOID COMBINING BEFORE RADIATING  SINCE COMBINING  IN SPACE IS ESSENTIALLY LOSSLESS &OR THIS REASON  MANY SOLID 
 Waterschoot, Lockheed Martin Maritime and Sensor Systems, Syracuse, NY . ch08.indd   13 12/20/07   12:50:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Van Nostrand Co., Inc.,  Princeton, N.J., 1961.  68. Hoare, E., and G. 
  D"  -(Z TRANSMIT PULSE BANDWIDTH   MS PULSE WIDTH W NO 0# #7 0HASE .OISE $ENSITY &LOOR   D"C(Z. {°Îä  2!$!2 (!.$"//+  4HE SYSTEM 
 TRACK SEPARATION RUN  )N ADDITION TO HEIGHT PRECISION  GEODETIC ALTIMETRY REQUIRES SMALLER ALONG 
 &REQUENCY "ANDS. £°£{  2!$!2 (!.$"//+  WITH FEW EXCEPTIONS  FOR AIRBORNE RADAR ALTIMETERS 4HERE ARE NO OFFICIAL )45 ALLOCATIONS  FOR RADAR IN THE (& BAND  BUT MOST (& RADARS SHARE FREQUENCIES  WITH OTHER ELECTROMAG 
 APERTURE 3"2 WOULD BE ON THE ORDER OF KILOMETERS .EVERTHELESS  THE RESULTS DID NOT MEET THE NEEDS OF THE SPONSOR  AND SO THE NOTIONAL SECOND AND THIRD MISSIONS WERE NEVER LAUNCHED 1UILL WAS THE ONLY !MERICAN 3"2 WHOSE DATA WERE OPTICALLY RECORDED ONBOARD  EVENTUALLY RETURNED TO %ARTH BY EJECTED CAPSULE  AND THEN COLLECTED BY AN AIRBORNE RETRIEVAL MANEUVER 4!",%  3YNTHETIC !PERTURE 2ADARS %ARTH 
 NOISE RATIO 3.2  AS DEFINED BY THE RADAR EQUATION %Q   4HE CONSTITUENT VARIABLES THAT APPEAR IN THE EQUATION HAVE BEEN DISCUSSED IN 3ECTIONS n  EMPHASIZING THE UNIQUE CONSIDERATIONS THAT ARISE WITH (& SKYWAVE RADAR  SO THE TOOLS FOR PERFORMANCE MODELING AND ANALYSIS ARE AVAILABLE "Y CONSIDERING THE CASE OF NOISE 
 Although only two receivers are  required instead of the three used in a monopulse tracker, the mechanical rotation of the two  0 1 2 3 4 5 6  Beam crossover, dB Figure 5.1 1 Slope of the angular-error  signal at crossover for a monopulse  and conical-scan tracking radar. 0, -  half-power beamwidt h, 0, = squint  angle.  164INTRODUCTION TORADAR SYSTEMS microwave combining circuitry. 
 (a) The soft rhumbatron TR cell [ 4]; (b) TR switch circuit.Airborne Maritime Surveillance Radar, Volume 1 3-7. that the gas was close to ionisation. A coupling loop into the rhumbatron terminated the quarter-wave line from the T junction. 
 Fuhrmann, E. Kelly, and R. Nitzberg, “A CFAR adaptive matched filter detector,”  IEEE Trans ., vol. 
 Moore, and A. K. Fung, Microwave Remote Sensing: Active and Passive ,  V ol. 
 SPACE LIMITATIONS   A SATELLITES POSITION AND VELOC 
 I £EE Trans.,  vol. AP-26, pp. 566-571, July, 1978. 
 ALARM RATE SIMILAR TO SURVEILLANCE RADAR (OWEVER  HIGH FALSE 
 Y . I. Abramovich, S. 
 K. Kamen: SCAMP-A New Ratio Computing Technique with Application to  Monopulse, Microwai•e J .. vol. 
 20, pp. 308-335,  June, 1959. .,' ; er. 
 70, arid 95 <ill?. I EEE I975 Irrtc~rrrctriorrt~l Rtrdur Cor!/i~rcrrcc>, Apr. 2 1 -23. 
 ,EVEL #ONTROL  !NOTHER WIDELY EMPLOYED USE FOR !'# IS TO  MAINTAIN A DESIRED LEVEL OF RECEIVER NOISE AT THE !$ CONVERTER !S WILL BE DESCRIBED IN 3ECTION   TOO LITTLE NOISE RELATIVE TO THE QUANTIZATION INCREMENT OF THE !$ CON 
 PASS FILTER WITH A NEARLY RECTANGULAR RESPONSE IS THEN APPLIED TO REJECT THE NEGATIVE 
 02& 2ANGE 7HILE 3EARCH  ! MEDIUM 
 STATE BOTTLE TRANSMITTER WHERE SIGNIFICANT LOSSES CAN  ACCRUE IN THE COMBINING CIRCUITRY  THE SOLID 
 Kanagaratnam,  J. Stiles, C. Allen, and K. 
 Thus, the bearing ofa target can bedetermined bynoting the bearing ofthe radar antenna when that target gives thestrongest echo signal. This can bedone ina variety ofways, and more precise and convenient means fordetermining target bearing bymeans ofradar have been developed (Chap. 6),but the method described here illustrates thebasic principle. 
 The weight of the solar system depends upon the orbital altitude and the operational requirement during eclipse. For a continuous-operation solar array at geosynchronous altitude, the 100-kW solar system weight is estimated to be 3970 kg. In comparing advantages and disadvantages, the solar-battery system is based on known technology, and extrapolation to a larger power output is considered to be an engineering design task. 
 CORRELATION OF EVERY POSSIBLE COMBINATION OF A  
 (This is tabulated in Table 2.6.) This discussion of A/D quantization noise has assumed perfect A/D converters.  Many A/D converters, particularly under high-slew-rate conditions, are less than per - fect. This, in turn, leads to system limitations more severe than predicted here (see  Section 2.13).FIGURE 2.79  Digital MTI consideration TABLE 2.6 Typical Limitation on I Due to A/D Quantization Number of Bits, N Limit on MTI Improvement Factor I, dB 10 59.0 11 65.0 12 71.0 13 77.0 14 83.0 15 89.1 16 95.1 ch02.indd   74 12/20/07   1:46:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 J. McLaughlin, “Validation  of first generation CASA radars with CSU-CHILL,” presented at 32cd Conf. Radar Meteorol. 
 AP-23,pp.358-367, May,1975. 55.Chuang, C.W.,andD.L.Moffatt: NaturalResonances ofRadarTargetsviaProny'sMethodand TargetDiscrimination, IEEETrans.,vol.AES-12. pp.583-589, November, 1976. 
 The signal-to-noise ratio is proportional to the size of the range resolution element and is independent of the size of the azimuth resolution element. 2. The signal-to-noise ratio is inversely proportional to the third power of range. 
 0%#&" .*%$   ( '+ $/) ! *   )! $"   ""%-&)) !"* ( ( )&%$) 
 They occur at angles given by sin 0 = ± [m/(s/\)]9 where m is an in- teger. For the half space given by -90° < 0 < +90°, there are 2m' grating lobes, where ra' is the largest integer smaller than s/K. If s < /, grating-lobe maxima do not occur, and the value at ±90° is cos (TTS/K). 
 1965.  117. SchclT. 
 The master oscillator consists ofapair of8025’s inpush-pull, theplate and grid circuits being tuned bytransmission-line elements ofvariable length. The amplitude ofoscillation iscontrolled bythe capacitive reactance ofthe filament line, and can also bevaried bychanging the length ofthe filament line. .Change ofchannel necessitates retuning of the r-fpower amplifier byadjustment ofashort-circuiting bar onthe parallel line which constitutes the plate load. 
 GRASP has popular GUI-versions that run  on Microsoft PC-based Windows operating systems (2000, 2003, NT, XP) as well as  LINUX. Although the GRASP code is PO-based, it also includes a Physical Theory of  Diffraction (PTD) option as well as a Geometrical Optics (GO)/ Uniform Geometrical  Theory of Diffraction (UGTD) option that can be turned on when needed. The code  is very general in that it can model standard conic section-based reflectors as well as  arbitrarily shaped surfaces or scatterers if desired. 
 RANGE CLUTTER AND WEATHER RETURNS COME FROM AMBIGUOUS RANGES   &)'52%  !NOMALOUS PROPAGATION DUCTING   A   
 At once you will see an important difference between  the jobs the X and the Y plates are expected to do. The  X plates are being fed with a regularly varying voltage,  produced by a local piece of apparatus known as the  time-base, to pull the spot across the tube, to black out  its return path, and then to set it going across again in  ouey the same path. This is a ‘home-made’ voltage,  ‘and we can make it as strong as we like within reason. 
 The difference innumbers ofcycles inthetwo halves ofthe modulation period isthen ameasure ofthe doppler frequency. This difference can bemeasured invarious ways, and has been used, along with thealtitude information, invarious dcvelop:nents ofthedevice here described. 5.9. 
 3!2 !N IMAGING RADAR  FOR THE #HANDRAYAAN 
 Test waveforms can be imported into  the generators,  synthesized, and  replayed. Signal generation is often required  in the selection and verification of analog transmitter  components to test the margin of design and manufacturing  processes.   Receiver Tests   Testing  the receiver  portion  of a radar  system , when  the  companion transmitter  is not yet available , requires  pulse   generation  equipment. 
 VIA (ARI 5571) and eventually by ASV Mk. VIB (ARI 5604). The background to the development of ASV Mk. 
 Milne, A. D. Olver  and P. 
 Height Finding Techniques in 3D Radars. There are many types of radars that provide 3D information by simultaneously measuring the three basic position coordinates of a target (range, azimuth, and elevation). In this handbook, however, the convention is followed in which a 3D radar is taken to be a surveillance radar whose antenna mechanically rotates in azimuth (to measure range and azimuth) and which obtains the elevation-angle measure- ment either by scanning one or more beams in elevation or by using contiguous, fixed-elevation beams. 
 Contents     xi   4.2 Magnetron Transmitters  .........................................  4.5  Limitations  .........................................................  4.5  Magnetron Features  .......................................... 
 The two links areordinarily connected automatically inasimple regular way and are uninfluenced byhuman reactions. Since the channels exist, how- ever, they afford the basis foracommunications system. Inthe past,. 
 WAVES DO &LEISCHMAN ET AL SEE ALSO 3ECTION  
 The main challenge with this tech - nique is that fixed clutter returns from many range ambiguities, as well as all targets  of interest, fold into the first range interval. Thus, excellent clutter rejection must be  provided to prevent folded clutter from suppressing targets of interest, which may  be at any true range. Technique 6. 
 5.19 describes the measured bounds of the lowest servo resonant  frequency as a function of antenna size achieved with actual tracking radars.  Antenna diameter - ft  Figure 5.19 Lowest servo resonant-frequency as a function of antenna diameter for hemispherical scan-  riing paraboloid reflector antennas. (Based or1 trteastrretnettts compiled by D. 
 The development of the magnetron was one of the most important  contributions to the realization of microwave radar.  The success of microwave radar was by no means certain at the end of 1940. Therefore the  United States Service Laboratories chose to concentrate on the development of radars al the  lower frequencies, primarily the very high frequency (VHF) band, where techniques and  components were more readily available. 
 AP-8, pp. 485-490, September, 1960.  91. 
 Direct microwave  analogy of the optical lens. (h) Zoned dielectric lens.  One of the limitations of the solid homogcncous·dielcctric lens is its thick size and large  weight. 
 D. W .. and F. 
 59. R. Jonker and A. 
 If all the frequencies in the band are used with equal weighting, then twice the bandwidth (half the pulse length) becomes acceptable. At a scan angle G0 the beam steers with frequency through an angle AG so that 5G « j tan G0 rad For wider bandwidths, time-delay networks have to be introduced to supplement the phase shifters. Conformal Arrays.I7J8 Phased arrays may conform to curved surfaces as re- quired, for example, for flush-mounting on aircraft or missiles. 
 SQUARED  DIGITAL NUMBERS AS  A     WHICH INDICATES  SIMPLY RADAR POWER PER PIXEL 4HIS HAS BECOME STANDARD PRACTICE WITH 2!$!23!4 
 TED AS WELL )NCREASINGLY  POLARIMETRIC DIVERSITY IS BEING IMPLEMENTED IN SPACE 
 H.: Diode and Ferrite Pnaser Technology," Phased Array Antennas," A. A. Oliner and  G. 
 M. Phillips, “Radar returns from the sea surface–Bragg scattering and breaking waves,”   J. Phys. 
 CAL RADAR SYSTEMS EXCEPT  FOR EXPERIMENTAL PURPOSES 3UPERRESOLUTION BASED ON A SMALL .   %,%#42/.)# #/5.4%2 
 J. W.. Jr.. 
 (a) Variation of power output,  efficiency, and peak voltage of the SFD-341 as a function of the input average power for a fixed frequency  (5.65 GHz); pulse width= 2.15 µs, duty cycle= 0.0009. (b) Variation of peak power output and peak  voltage of the SFD-341 with frequency for a fixed current (23.9 A); pulse width = 1.8 µs, and duty  cycle = 0.0009. (c) Variation of frequency with current for the SFD-377 A X-band coaxial magnetron at a  frequency of 9.373 GHz, with 0.001 duty cycle, and 1.0 µs pulse width (Courtesy Varian Associates, Inc.,  Bet•erly, MA.) . 
 Building ani-famplifier with this gain while avoiding trouble with regenerative feedback hasbeen one ofthemost difficult problems in radar receiver design. Ground current loops must beconfined bycareful bypassing and grounding; power leads must beproper] yfiltered; coils must bewound and spaced intelligently; theshielding must beadequate. Careful attention must bepaid toallofthese items iftheover-all response characteristic istobear any resemblance towhat isexpected. 
 The fundamental limit on achievable accuracy is the target's own angle noise (glint, scintillation, and depolarization). Other noise contributors must be mini- mized by proper design (i.e., maximize signal-to-noise ratio to minimize range- dependent noise, reduce the range-independent noise—servo and other instru- mentation noise). Also, the correct angle measurement scale factor must be maintained over the full range of signal levels and over all look angles. 
 CLUTTER VISIBILITY OBLIGES THE RADAR DESIGNER TO ENSURE THAT THE RECEIVING  SYSTEM AND SIGNAL PROCESSING OPERATIONS DO NOT UNWITTINGLY DEGRADE THE RADAR PERFOR 
   PP n  -ARCH    ' 6 4RUNK  h$ETECTION RESULTS FOR SCANNING RADARS EMPLOYING FEEDBACK INTEGRATION v  )%%% 4RANS   VOL !%3 
 The pulse pair consists of a 1-jxs CW pulse that provides cover-Parameter Frequency RF power output (CW) Gain Spurious RF output (near-in) Spurious RF output (far-out) RF dc efficiency Input return loss Power output similarity (Ia) Phase similarity (Ia) DC voltages Size Weight Operating ambient temperatures PressurizationPerformance 216.98 MHz 320.0 W 17.1 dB -75 dBc -85 dBc 61.5 percent 14 dB 0.29 dB 3.0° 28 V/16.5 A and 8.9 V/0.18 A 21 x 16 x 4.3 in 47 Ib 0-1160F 5 lb/in2Specification 216.98 MHz 30OW + 0.5 dB 16.8 dB —70 dBc maximum — 80 dBc maximum 58 percent minimum 14 dB 0.5 dB 3° 28 V/19 A and 8.9 V/0.2 A 21 x 26 x 4.3 in 47 Ib 0-1160F 5 lb/in22566 EUOOEHTS 2556 ELElOENTS 225W EACH 144 ELEMENTS226W EACH 144 ELEMENTS30OV EACH 144 ELEMENTS30OW EACH 144 ELEMENTS IDB LOSS 60 KW TUBE TXfI50 KV TUBE TX UB IB BAYS TOTAL 18 BAYS TOTAL DRIVER 2-50KV TUBESDEIVER Z-SOOW SSM1S EXCITEREXCITER 30OV SSM Before (tube system) After (solid-state system) Transmitted powerTransmission efficiencyMaximum power in coaxialOverall site efficiencySite availability576 kW80%4OkW26.4%0.8767 kW95.9%1.8kW52.6%0.9998 . FIG. 5.17 NAVSPASUR transmitter amplifier module. 
 Furthermorej the capacity coupling through the two triodes adds, whereas inthe diode circuit the effects ofthe opposite waves tend tocancel. Onthe other hand, the double-triode circuit ismuch thecheaper, particularly ifaspecial driving circuit must beprovided forthediodes.. 508 THERECEIVING SYSTEM—INDICATOR [SEC. 
 52. Ulaby, F. T.. 
 Geophys. Res. , vol. 
 The contours of constant doppler are perpendicular to  the .u axis, and contours of cbnstailt range lie parallel to the x axis.  If the angle of target rotation over which the doppler is observed is too short, the doppler  spectrum is broad and the resolution is low. Increasing the observation time narrows the  spectrum arid the rcsolutiori will increasc. 
 (number of values in range Ax at x )/ Ax p X = Im  &x ... 0 total number of values= N (2.8)  N ... oo  The probability that a particular measured value lies within the infinitesimal width dx  centered at x is simply p(x) dx. 
 (9) Here, B⊥,total=2N·Bsinα·sinθis the total orthogonal baseline. The elevation range after elevation processing is [−Hmax/2, Hmax/2], where the maximum ambiguity in elevation Hmaxis: Hmax≈λr/(2Bsinα·sinθ). (10) From Equations (3) and (7), it can be seen that the signal in (r/prime,y/prime,0)occurs at (r/prime,y/prime,−y/primecotα/sinθ) after elevation processing, which means the azimuth signal of the target will be located at di ﬀerent positions in elevation, i.e., the mainlobe and sidelobes along the azimuth of the focused target will 42. 
 In such case it always requires a large number of SAR images for statistical analysis to determine approximate sparsity Krange of different kinds of observation scenes, and then obtain the optimal sparsity Kwithin the determined range by the optimization criteria. 161. Sensors 2018 ,18, 3750 3.4. 
 It is also subject to multipath and to phase reversals if coherent operation is required across transmitter antenna sidelobes. However, this latter problem can be overcome by a Costas loop for phase reversals near ISO0.134 An extension of direct-path phase locking is the use of the direct-path signal as a reference sig- nal in a correlation processor.135 For direct-path phase locking, clock stability is A<J>/2iT/Ar, where A<|> is the allowable rms sinusoidal phase error,/is the transmitter frequency, and AT is the difference in propagation time between the transmitter-target-receiver path and the transmitter-receiver (direct) path.133 As with time synchroniza- tion, this requirement can usually be satisfied by a temperature-controlled crystal oscillator. For matched stable clocks in the transmitter and receiver, phase stability is usually required over a coherent processing time T. 
 M. FukS, A. 1. 
 ,/1, 
 The data were recorded directly onto  70-mm photographic film, which was processed through a combination of optical  and digital means following return of Apollo 17  to Earth. (Optical processing was the  state-of-the-art back in 1972 for SAR data.) Penetration depths proved to be approxi - mately proportional to wavelength. The radar’s waveform was constrained so that all  sidelobes were at least 45 dB below the main-beam peak for all responses beyond three  impulse widths of the compressed signal. 
 ELEMENT PHASE RIPPLES WITH A  PEAK 
 LIMITED ALTIMETER IS MUCH LESS SENSITIVE TO SMALL  ANGULAR POINTING ERRORS THAN IS THE CASE FOR A BEAM 
 Later versions of the attenuator only operated on the transmittedsignal and a system (attenuator type 58) was introduced on ASV Mk. VIB for automatically increasing attenuation with time, at a rate selectable by the operator. In terms of detection ranges, it was noted that sea returns were, as expected, more extensive on ASV Mk. 
 ING IN A LENGTHENING OF THE REFLECTOR SYSTEM ALONG THE FOCAL AXIS  4HE PARAMETERS OF THE #ASSEGRAIN REFLECTOR  ARE RELATED BY THE FOLLOWING EXPRESSIONS   TAN  XV     $M  FM    TAN XV   TAN XR   FC  $S           E   ,V  FC  &)'52%   !32 
 Example 1: The Experimental Validation Using ENVISAT-1 ASAR Image Figure 5is an ENVISAT-1 ASAR IM image acquired in Luson Strait, on 27 April 2005 at 01:53:42 UTC. The related radar parameters are listed in Table 3. Frame A (20 km ×20 km) highlights a shear-wave-generated eddy with a diameter of about 11.2 km, which is shown in detail in Figure 6. 
 14, March 1974. 41. Large Furlable Antenna Study, Lockheed Missiles and Space Company, Rept. 
 Qi, R.; Jin, Y. Analysis of the effects of Faraday rotation on spaceborne polarimetric SAR observations at P-band. IEEE T rans. 
 SCANNING DOPPLER RADAR !NY RAPID 
 LIKE JAMMING !LSO  3," IS EFFECTIVE AGAINST COHERENT REPEATER INTERFERENCE #2)  HERE hCOHERENTv MEANS THAT THE INTERFERENCE TRIES TO MIMIC THE CODED WAVEFORM RADIATED BY THE RADAR APPEARING AS A SPIKE SIGNAL AFTER PULSE COMPRESSION n  !  METHOD OF ACHIEVING THIS IS TO EMPLOY AN AUXILIARY ANTENNA COUPLED TO A PARALLEL RECEIV 
 Pathak, “A uniform theory of diffraction for an edge in a perfectly  conducting surface,” Proc. IEEE , vol. 62, pp. 
 Substituting 11</> = 2n into Eq. (3.17) gives the maximum unambiguous  range as )./2. At radar frequencies this unambiguous range is much too small to be of practical  interest. 
 Periodic waveforms are obtained when the shift-register generator is left in continuous operation. They are sometimes used in CW radars. Aperiodic waveforms are obtained when the generator output is truncated after one com- plete sequence. 
 Currie, N. C.. f. 
 The intent of this section is to show the necessary radar  system and radar target inputs needed by the AREPS program. These inputs are shown  in Figures 26.13 and 26.14. For a complete description of each input parameter, you  may refer to the AREPS online help or the AREPS operator’s manual.FIGURE 26.12  AREPS computations display within SIMDIS showing radar probability of detection of a  small target under the influence of terrain-masking effects ch26.indd   23 12/15/07   4:53:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 TION BETWEEN RADAR AND )&& RETURNS  BUT ALSO SUPPORTS FAST SETUP AND TEARDOWN TIME FOR TRANSPORTING THE RADAR IN ITS MOBILE CONFIGURATION *OINT 34!23 !NTENNA  4HE *OINT 3URVEILLANCE 4ARGET !TTACK 2ADAR 3YSTEM  *OINT 34!23  PROVIDES LONG 
 A novel SAR sidelobe suppression method via Dual-Delta factorization. IEEE Geosci. Remote Sens. 
 Itdiffersfrom theklystron inhavingwiderbandwidth, butattheexpense oflessgain.Thecrossed-field amplifier isofthesamegeneral familyasthemagnetron andsharessomeofitsproperties, especially smallsizeandweight,highefficiency, andanoperating voltagemoreconvenient thanthatoftheklystron andthetraveling-wave tube.Likethetraveling-wave tube,ilenjoysa widebandwidth; butitisofrelatively lowgainandtherefore requires morethanonestagein theamplifier chain.Themagnetron andthecrossed-field amplifier aredeviceswhichutiliLethe properties ofelectron streams incrossed electricandmagnetic fields.Theklystron andthe traveling wavetubeareofadifferent familyknownaslinearbeamtubes. ••RadarsatVHFandUHFhaveoftenemployed grid-controlled triode.and tetrodetubes. Thesehaveusuallybeen,inthepast,competitive incosttootherpowergeneration meansat thesefrequencies. 
 Jamming sources may be located on the target platform itself (self-screening)  and received by the main antenna beam or radiate from a separate location (stand-off)  and be received mainly through the antenna beampattern sidelobes. The jamming sig - nal may be incoherent with the radar waveform and operate in a “spot” or “barrage”  fashion to raise the noise floor in both range and doppler search spaces to potentially  impair detection performance, or it can be coherent with the radar waveform, as in the  case of deception jamming, which may generate false targets and potentially impair  the tracking system from following the true target. Impact of Ionosphere. 
 The vertical sheet ofradiation isobtained bythree separate transmitters feeding ahorn and aseries ofdipoles. The slant beam uses only two transmitters, since early-warning range isordinarily not needed onthe slant beam which isintended forheight-finding. The results ofheight calibrations show that heights can becalled rapidly toanaccuracy of~1000 ftand, with care, to+500 ft. 
 vol /\l.'S-6. 1'1). 313 323. 
 Rottger, J., and M. F. Larsen: Clear Air Radar Techniques, invited paper, 40th Conf. 
 However, most radar targets do not  move in a random maneuver but instead move linearly at times and then maneuver  unpredictably at times. The challenge in adapting the filter to deal with changes in the  target motion (e.g., maneuvers, ballistic re-entry) is to adapt the target motion model  for the Kalman filter over time so that more accurate tracking occurs than with a single  model. The simplest form of adaptation is a maneuver detector to monitor the tracking  filter residuals (differences between measured and predicted position). 
 BASED COMMAND TRANSMITTER IN THE RECEIVER 
 Ineither case, thereeeiver ofthebeacon signals does notreceive radar echoes since itisnottuned forthem. Thus, Receiving Transmitting antenna JLJantenna )b Transmitter +-Modulator Coder 7( or simple triqer Recewer +Decoder (optional) FIG.S.I.—Block diagram ofabeacon. the beacon signals are separated from radar reflections and can bedis- played without being swamped byheavy permanent echoes. 
 DENCE ON THE NUMBER OF INDEPENDENT SAMPLES FOR A HORIZONTALLY TRAVELING SCATTEROMETER WITH A FORWARD 
 Figure 10.50 has a wideband input transducer and a frequency-selective (dispersive) out- put transducer. When an impulse is applied to the input, the output signal is ini- tially a low frequency that increases (based on the output transducer finger spac- ings) at later portions of the pulse. This results in an up-chirp waveform which would be a matched filter for a down-chirp transmitted waveform. 
 maxima) and for any propagation gain or loss that would not occur in free space. The most common of these effects are absorption, diffraction and shadowing, certain types of refraction effects, and multipath interference. For a target in free space and in the maxima of both the transmit and receive antenna patterns, Ft = Fr = 1. 
 The 1.6° by 3.2° monopulse beam set is electronically phased-scanned from -1 to 19°.22-24 Fixed- site variants of this radar are the AN/FPS-117 SEEK IGLOO radar (Fig. 20.2c) and the GE-592 radar, both of which are distributed aperture solid-state and sim- ilar to the AN/TPS-59 but which employ a 24- by 24-ft array antenna with 44 rows and additional digital signal processing. The square-aperture array of the GE-592/ FPS-117 radar generates a 2.2° azimuth by 2° elevation two-axis monopulse beam set.25-28 The HADR, deployed mainly in Europe for North Atlantic Treaty Organiza- tion (NATO) applications, is a ground-based 3D S-band phased array radar which also uses phase scanning in elevation and mechanical rotation in azimuth. 
 Alternatively, the waveform may be generated at a low-power level and amplified  in a power amplifier. This is the more usual procedure. The waveform may be generated by a  number of means including a voltage-controlled oscillator whose frequency is made to vary . 
   NO     PP n  3EPTEMBER   * 7 4AYLOR AND ( * "LINCHIKOFF  h1UADRIPHASE CODE 
 UOUS AND DOPPLER 
 GATIONAL PURPOSES .OT ONLY DOES IT PROVIDE A SUITABLE NAVIGATIONAL TOOL BUT ALSO ITS TRANSMISSIONS ARE IDENTICAL TO CONVENTIONAL COMMERCIAL TRAFFIC  ALLOWING SAFE NAVIGA 
 RATE PROBLEM 4HE ONLY DEGREE OF FREEDOM REMAINING IN THE DATA 
 REFERENCES l.Ridenour, L.N.:"Radar System Engineering," MITRadiation Laboratory Series,vol.I,p.592. McGraw-Hili BookCompany, NewYork,1947. 2.Lawson. 
 OUTPUT TUBE WITH A MULTISTAGE DEPRESSED COLLECTOR )T  IS A LINEAR AMPLIFIER WHOSE PRIME POWER CAN BE PROPORTIONAL TO  THE OUTPUT POWER  PRO 
 FREQUENCY WAVEFORM OF BANDWIDTH " IS   DRC"     !LTHOUGH IT IS BEYOND THE SCOPE OF THIS CHAPTER  IT CAN BE SHOWN THAT SUCH A RANGE  RESOLUTION OF  y C" MAY BE OBTAINED USING A WIDE VARIETY OF WAVEFORM TYPES  AS LONG  AS THE OVERALL TRANSMITTED BANDWIDTH IS  " &OR EXAMPLE  3ECTION  OF 3ULLIVAN SHOWS  THAT THIS IS TRUE FOR THE ,&- WAVEFORM #ROSSRANGE 2ESOLUTION  ,ET US NOW ASSUME THAT THE AIRBORNE OR SPACEBORNE  3!2  IS OBSERVING A SCENE ON THE %ARTHS SURFACE CONSISTING OF A FEW POINT TARGETS AND THAT IT TRANSMITS AND RECEIVES  . IDENTICAL PULSES EACH OF BANDWIDTH  " PRESUMABLY  THOUGH NOT  NECESSARILY  VIA THE ,&- WAVEFORM  AND DETERMINES THE DOWNRANGE POSITION OF EACH  &)'52%   2ANGE AND CROSSRANGE RESOLUTION 3IMILAR DISCRETE &OURIER TRANSFORM $&4  PROCESSES MAY  BE USED TO OBTAIN RANGE AND CROSSRANGE RESOLUTION  "          
 The new phase shift is now within ±90o,  and the algorithm proceeds normally. Next, the algorithm loops through  N iterations with the goal of driving  the residual phase error, f, to zero. In  each iteration, a new f is calculated by  subtracting or adding the phase shift for TABLE 25.1  CORDIC Parameters for First Eight Stages i tan(q  i) q  i (deg) cos(q  i) P [cos(q  i)] 0 1 45.000 0.707107 0.707107 1 1/2 26.565 0.894427 0.632456 2 1/4 14.036 0.970143 0.613572 3 1/8  7.1250 0.992278 0.608834 4 1/16  3.5763 0.998053 0.607648 5 1/32  1.7899 0.999512 0.607352 6 1/64  0.8951 0.999878 0.607278 7 1/128  0.4476 0.999970 0.607259 FIGURE. 
 Fedder, “SAMI2 (Sami2 is another model of the ionosphere),  A new low-latitude ionosphere model,” J. Geophys. Res ., vol. 
 10 INTRODUCTION TO RADAR SYSTEMS  never carried out, however. The limited ability of CW wave-interference radar to be anything  more than a trip wire undoubtedly tempered what little official enthusiasm existed for radar.  It was recognized that the limitations to obtaining adequate position information coiild  be overcome with pulse transmission. 
 Krason. II .. and G. 
 02& RADAR IS A HIGH 
 3IDE ,OBE 2ATIO 2#3 2ADAR #ROSS 3ECTION 2& 2ADIO &REQUENCY 2&) 2ADIO &REQUENCY )NTERFERENCE 2&- 2ANGE &ILTER -AP 2'0/ 2ANGE 'ATE 0ULL /FF 272 2ADAR 7ARNING 2ECEIVER 2MS 2OOT -EAN 3QUARE 273 2ADAR 7ORK 3TATION 28 2ECEIVER 3!2 3YNTHETIC !PERTURE 2ADAR 3!7 3URFACE !COUSTIC 7AVE 3).2 3IGNAL 
 These changes make thecircuit simpler and avoid theproblems ofcarrier modulation and demodulation. However, the loss offreedom inthe choice offrequency forthe delay line and the comparison amplifier isa disadvantage. Also, themethod isnotsuitable for“back-of-dish” radar sets, since the i-fsignals cannot conveniently bebrought out through slip rings. 
 Winston S., 138  Console, 127  Cossor oscillograph, 77-78  Crystal capsule, 121  D.C. RESTORER, 98  Decca (QM), 127  Dee, Professor P. I., 28 Deflection, electromagnetic,  65-66; electrostatic, 65-  66  Dippy, R. 
 It is calculated by W=n ∑ k=1R(k) R(k)max. (4) First, calculate the energy concentration parameter of the RCS curve and round it up to an integer W. Sort the RCS amplitudes in descending order and remove the top Wamplitudes. 
 15. Guest editorial and invited papers reviewing OTH radar technology, with emphasis on recent  progress, Radio Science , vol. 33, July–August 1998. 
 19, pp. 19-24, December, 1976.  93. 
 7.64  7.10 Solid-State M odules  ...............................................  7.67  7.11 Phased Array Systems  ...........................................  7.69  8. 
 Figure 12. SPARX SNR estimated map (in dB). Overlapping the acquired SNR map (Figure 12) with the scenario top view (Figure 11) it is possible to identify every strong measured signal with a speciﬁc reﬂecting target inside the acquisition scenario (Figure 13); although it should be noted that, due to prototype’s low azimuth resolution, imaging of the farthest structures becomes rather coarse. 
 32. I. J. 
 276 ANTENNAS, SCANNERS, ANDSTABILIZATION [SEC. 9.3 ray optics. Figure 9.10 shows two distortions ofaparaboloid used for this purpose. 
 ING BETWEEN CLUTTER AND OTHER FORMS OF INTERFERENCE )N OTHER WORDS  THE ADAPTED PAT 
 6, pp. 334-339, November, 1967.  60. 
  
 69. JI~SICSCII. I) R.: 1)i;ttllernly Vcrsi~s 1111' Microw;tves and Otlicr Radio-freqi~ency Radiations: A Rose by  Atlothcr Nnnle is a C'nhhngc. 
 TION IN THE BACKSCATTERED FIELD !N ANTENNA COMPRISED OF TWO LINEAR ARRAYS SUCH AS ( AND 6  WILL RADIATE A CIRCULARLY  POLARIZED FIELD IF THE SETS OF ELEMENTS ARE DRIVEN SIMULTANEOUSLY AND  n OUT OF PHASE   AS SHOWN IN &IGURE  )N PRACTICE  THE AMPLITUDE WEIGHTING AND RELATIVE PHASING OF THE ARRAYS WILL SELDOM BE PERFECT !S A RESULT  THE RADIATED FIELD WILL BE SOMEWHAT ELLIPTICAL  RATHER THAN PURELY CIRCULAR 4HE HYBRID 
 FORM $IGITAL FREQUENCY 
 T able 1. Radar System Parameter. Parameters V alue Time width 10 s Band width 12 MHz Pulse repetition frequency 2500 Hz Azimuth beam width 3.2◦ Coherent pulses 128 Range gate number 2048 The injected signal just exist about 0.05 s in the slow time domain, which corresponds to about 128 pulses in one CPI with the given dwell time. 
 347–349, May 1960. 12. P. 
 15,  McGraw-Hill Book Company, New York, 1948.  17. Dickens, L. 
 85-87, January, 1956.  11. Agar, W. 
 Similarly, in a stage with N modules in parallel, each with its own high-frequency power-conditioned power supply, the overall phase ripple can usually be assumed to be reduced by a factor equal to the square root of N if the power supply clocks are purposely not synchronized. 2. Because of saturation effects amplitude errors in cascaded stages do not simply add. 
 The same would be true for an array of  tiipoles. To avoid ambiguities, the backward radiation is usually eliminated by placing a  reflecting screen behind the array. Thus only the radiation oyer the forward half of the antenna  ( - 90" 5 O 5 90") need be considered. 
 (1) Phase-shifter designs generally utilize either a switched- line or a loaded-line circuit configuration, using either distributed transmission- line components or lumped-element equivalent circuits, to achieve multiple-bit phase shifting. Switched-line configurations rely on FET switches to switch lengths of transmission line in and out of the circuit and are typically used for higher frequencies where less chip area is needed. Loaded-line configurations use the switched FET parasitics as circuit elements to introduce the necessary phase changes. 
 Polyphase codes can be considered as complex sequences whose elements have  a magnitude of one, but with variable phase.30 The phases of the subpulses alternate  among multiple values rather than just the 0 ° and 180 ° of binary phase codes. These  codes tend to be discrete approximations to LFM waveforms, and hence possess simi - lar ambiguity functions and doppler shift characteristics. The autocorrelation functions  are similar, with a peak to sidelobe ratio of about N. 
 (Photograph courtesy of Raytheon Company.) REFERENCES 1. Skolnik, M. L: The Application of Solid-State RF Transmitters to Navy Radar, NRL Memo. 
 Shnidman, “Determination of required SNR values,” IEEE Transactions on Aerospace and  Electronic Systems,  vol. 38, no. 3, pp. 
 ..  scr. 11, vol. 
 The wetting of surfaces through which signals are  transmitted should be avoided. Also, adequate drainage should be provided to prevent the  accumulation of water in the reflector. Ice coating a reflector surface does not usually cause a  problem. 
 In this paper, the frequency approach has been used to obtain the focused image. A block diagram of the complete algorithm is reported in Figure 7. 3.2.2. 
 The narrower the pulse, the more accurate the measurement of range and the broader  the transmitted spectrum. A widely used technique to broaden the spectrum of CW radar is to  frequency-modulate the carrier. The timing mark is the changing frequency. 
 Whenextreme structural rigidityorbroadband capabilities arerequired withrelatively lightweight,multiple-layer sandwiches ofseven,nine,eleven,ormorelayersmaybecon­ sidered. Aircraft radames, especially thoseusedatsupersonic speeds,aresubjecttomechanical stressandaerodynamic heatingsoseverethattheelectrical requirements ofradomes madeof dielectric materials musthesacrificed toohtainsufficient mechanical strength. Theradome. 
 SEC. 144] MOTOR-ALTERNATOR SETS 561 4.Mechanical vibrators. Low-voltage d-c input, output direct current or120-cps alternating current orany combination. 
 28. Rowlands, R. 0.: Detection of a Doppler-Invariant FM Signal by Means of a Tapped Delay Line, J. 
 SIGNAL RATIO OTH 
  ANTENNA PATTERN AND THE CORRESPONDING FREE 
 To minimize field degradation, radars should be designed with built-in automatic  performance-monitoring equipment. Careful observation of performance-monitoring instru­ ments and timely preventative maintenance can do much to keep radar performance up to  design level. Radar characteristics that might be monitored include transmitter power, receiver  noise figure, the spectrum and/or shape of the transmitted pulse, and the decay time of the TR  tube. 
 This isacompromise between aratio of3.60 (77ohms), which, foragiven outer diameter, gives the lowest attenuation due toconductor losses, and aratio of1.65 (3oohms) which maximizes the power that can becarried with agiven breakdown voltage gradient. Since the attenuation ina50-ohm line isonly 10per cent greater than itisina77-ohm line, itisnot acostly compromise. Increasing thesize ofboth conductors toincrease theairgap and thereby increase the power-carrying capacity cannot becarried onindefinitely, since ahigher mode ofpropagation, with diametral rather than axial R symmetry, can beexcited when the mean circumference ofthe annular dielectric space exceeds one wave- length. 
 The solution of the wave equation is most useful for those systems  in which the equation is separable into ordinary differential equations in each of the  variables. The scattered fields are typically expressed in terms of infinite series, the  coefficients of which are to be determined in the actual solution of the problem. Once  obtained, the solution allows the fields to be calculated at any point in space, which  in RCS problems is the limit as the distance from the obstacle becomes infinite. 
 To  maintain modest losses, surface errors must be tightly  controlled. Another consideration in mesh reflectors is system - atic surface deformation. For many reflectors, a mesh  is attached to a metal or composite backing structure. 
 In some cases the  monostatic cross section will be greater; in others, the bistatic cross section will be greater. But  on the average, the two will vary over comparable values.  The case where = 180" (forward scatter) is not covered by the above theorem. 
 82. Nathanson, F. E.: Adaptive Circular Polarization, IEEE 1975 lrtternutionril Radar Con/c'rrticc, Apr. 
 n   P    n  THERE ARE  M` GRATING LOBES  WHERE  M` IS THE LARGEST  INTEGER SMALLER THAN  SK )F S   K  GRATING 
 14.26  14.11 Triangular and Sawtoot h Modulation  ......................  14.27  14.12 Noise Modulat ion  ....................................................  14.28  14.13 Coded Modulati ons  ................................................. 
 5. Discussion 5.1. Comparison with Previous Studies In this study, SBAS-InSAR method with Radarsat-2 data is reliable for longtime monitoring of land subsidence covering a large area in Wuhan city (October 2015 to June 2018). 
 TIONS  AND PROPAGATION FROM NEIGHBORING REGIONS WITH DIFFERENT WIND STRESS 4HEY ARE VERY IMPORTANT FOR REMOTE SENSING AND IMPACT STRONGLY ON TARGET DETECTION BECAUSE THE SECOND 
 BAND LINEAR ARRAYS OF CANTED DIPOLES WITH  
 The ability to predict these obscured bands by  means of Eq. 20.6 can be exploited for HF radar design and siting and for scheduling  ship detection operations. Thus combining Eq. 
 Figure 12.23 shows these. For like- polarized waves, one can break scatter into three angular regimes: near-vertical (the quasi-specular region), intermediate angles from 15 to about 80° (the plateau region), and near-grazing (the shadow region). Cross-polarized scatter does not have separate quasi-specular and plateau regions (the plateau extends to verti- cal), and too little is known to establish whether a shadow region exists. 
 Schelonka, E. P. : Adaptive Control Techniques for On-Axis Radars, IEEE 1975 Internarionul R~dur  Conference, Arlington, Va., April 21-23, 1975, pp. 
 A constant rate of change of phase with time is  equivalent to a constant frequency. Thus a frequency difference at adjacent elements results in  a sca~lning beani. If tlie LOs in the mixers of Fig. 
 The receiver operates from a separate antenna (electrically isolated). The output of the receiver is detected, averaged, and displayed on a meter, oscilloscope, or other display or recorder. Its sensitivity must be checked by use of a calibration source. 
 15.20 Comparison of MTI improvement factor of binomial-weight MTI and optimum MTI against a gaussian-shaped clutter spectrum. numbers of pulses in the MTI (three to five) the binomial coefficients are remark- ably robust and provide a performance which is within a few decibels of the op- timum. Again, it should be noted that any attempt to implement an MTI canceler, which performs close to the optimum, would require the use of adaptive tech- niques which estimate the clutter characteristics in real time. 
 DESERT  WET  8 BAND   8 BAND 8 BAND66   66 (( 66 ((   n       n     n    n           n      n                  4!",%  3UMMARY OF -EASUREMENT 0ROGRAMS FOR "ISTATIC 3CATTERING #OEFFICIENT  S" )N 
 Integrated space geodesy for mapping land deformation over choushui river ﬂuvial plain, Taiwan. Int. J. 
 Inany case, ifthedirectivity oftheantenna pattern issuch that very little energy strikes thereflecting surface, Condition 2isfulfilled. Any implications ofConditions 3and 4 which arenotself-evident will beclarified inthelast part ofthis chapter, where other types ofpropagation will bediscussed. If,now, these condi- tions offree-space propagation apply, the result isvery simple: The transmitted wave, atany considerable distance from the antenna, 1has spherical wavefronts—limited inextent,. 
 ISOTRO 
 CASINC;  \   4T 4 EJF TD=RECT  P    ,&- 2ANGE 
 An absolute frame for position  and velocity may be obtained from the global positioning system (GPS) , a constella - tion of at least 24 satellites in polar Earth orbit providing continuous reference signals  for determination of precise position and velocity.28 Slant and Ground Planes.  When a SAR image is initially produced, the range  pixel size dr is usually a constant. (It is generally chosen to be somewhat less than c/2B,  e.g., 0.75 ( c/2B), to ensure adequate sampling). 
 39.Jones.CW.:Broad-Band Balanced Duplexers, IRETrans.,vol.MIT-5, pp.4-12,January, 1957. 40.Brown,N.J.:Modern Receiver Protection Capabilities withTR-Limiters, Microwave J.,vol.17,pp. 61-64.February, 1974. 
 OGY SURVEY PRESENTED IN 2ABINER ET AL )T CAN BE SHOWN THAT AN -4) FILTER AS SHOWN IN &IGURE  CAN BE DIVIDED INTO A  CASCADE OF SECOND ORDER SECTIONS AS SHOWN IN &IGURE  7HEN A NUMBER OF SINGLE 
 94-100, 1955.  81. Hendry, A., and G. 
 Naval Research Laboratory, Washington. D.C., pp. 9-14, December. 
 Ê 
 377–445, 1908. 34. J. 
 TIME  HAS BEEN PROPOSED IN &ABRIZIO ET AL   TO JOINTLY CANCEL SIDELOBE AND MAIN 
 E. B. Hogenauer, “An economical class of digital Filters for decimation and interpolation,” IEEE  Transactions on Acoustics, Speech and Signal Processing , vol. 
 TICS 2ANGE AND VELOCITY ACCURACY IS DEGRADED IN PULSE DOPPLER RADARS STATIONARY TARGET CANCELLATION IS IMPAIRED IN -4) MOVING 
 The range coverage, which totaled 47.5 nmi in the original  implementation, is divided into nmi intervals and the azimuth into $-degree intervals, for a  total of 365,000 range-azimuth resolution cells. In each $-degree azimuth interval (about  one-half the beamwidth) ten pulses are transmitted at a constant prf. On receive, this is called a  coherent processing interval (CPI). 
 Figure 4.7. Switch unit type 207B [ 6]. Figure 4.6. 
 The operational scenario in which ESM should operate is  generally crowded with pulsed radar signals: figures of 500,000 to 1 million pulses per  second are frequently quoted in the literature.9 The center frequency, amplitude, pulse  width, time of arrival (ToA), and bearing of each detected pulse are measured, con - verted in digital format, and packed into a pulse descriptor word (PDW). The train of  PDWs are sent to a pulse-sort processor that deinterleaves the sequences belonging to  different emitters and identifies Pulse Repetition Interval (PRI) values and modulation  laws (random jitter, stagger, switching). Further comparison against an emitter data - base, which contains the range of characteristic parameters (frequency, pulse width,  PRI), the related pattern of agility (random, stagger, etc.) for each emitter, the type of  antenna scanning pattern and periods permits the generation of an emitter list with an  identification score. 
 The retrograde polar orbit had an inclination angle of 108° and a period of 100.5 min. Three radar and two radiometer sensors were carried on the spacecraft. The coherent SAR, de- scribed in Sec. 
     4HE MATCHED FILTER INPUT SIGNAL IS ASSUMED TO HAVE ZERO TIME DELAY AND A DOPPLER  SHIFT FD   ST UTEJF TD    P    o  4HE TERMINOLOGY FOR THIS FUNCTION IS NOT STANDARDIZED IN THE LITERATURE 7OODWARD USES THE TERM CORRELATION FUNC 
 Anexample oftheelevation angleerroratlowanglesisshowninFig.5.16foratargetat constant height.43Atcloserangethetargetelevation angleislargeandtheantenna beamdoes notilluminate thesurface; hencethetracking issmooth. Atintermediate range,wherethe elevation angleisfrom0.8toasmuchassixbeamwidths, thesurface-reflected signalenters theradarbymeansoftheantenna near-insidelobes. Thesurface-reflected signalissmallso thattheantenna makessmalloscillations aboutsomemeanposition. 
 Atany given time itmay not beexact, because special emphasis may have been given toobtaining high peak powers ataparticular wave- length and abetter design evolved asaresult. Inthelong run, however, the validity ofthe rule isreestablished, because any new design can, within limits, beused toadvantage atother wavelengths. PulsePower.-The most outstanding characteristic ofpulsed micro- wave magnetrons istheir extremely high pulse power output, made pchsible bythevery large emission yielded byoxide cathodes when pulsed,. 
 Clutieratmillimeter wavelengths. Inchap.13itwasimpliedthatknowledge ofradarclutter characteristics atmicrowaves waslessthandesired.Thereisevenlessinformation onclutterat frequencies above10GHz.Detailswillnotbegivenhere,butthegeneral trendswillbe summarized fortheseveraltypesofclutterthathavebeenmeasured. Theav'hagecluttercrosssectionperunitareaforonesetofmeasurements oftreesand vegetation atmillimeter wavelengths isgivenby75.102 o-°(dB)=-20+10log(8/25)-1510g...1. 
 BASED 3!2S "URST MODE ALONG A SINGLE IMAGED SWATH IMPLIES A REDUCED DATA RATE  WHICH MAY BE NECESSARY TO MEET THE STRIN 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20   blind folio 20.84 ch20.indd   84 12/20/07   1:17:25 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
   2!$!2 #2/33 3%#4)/.   £{°ÓÎ 4HE THREE PATTERNS EACH COVER A n SECTOR FROM BROADSIDE TO EDGE 
 SHAPING TECHNIQUES TO ACHIEVE IMPROVED 3.2 IN THE  BANDWIDTH OF INTEREST .OISE SHAPIN G MAY BE EITHER LOW 
 Highly important is the fact  that the transmit pulse and its bandwidth are not changed; consequently, increased fre - quency allocation to make use of the higher range resolution is not an issue. Short Dwell Time Spectra (Maximum Entropy).  Spectral processing of  weather echoes adds another degree of freedom (the frequency dimension) to the abil - ity to discriminate signal from ground clutter, other artifacts, and noise, and to estimate  meteorological parameters of interest. 
 MER 4HE DECOY IS DEPLOYED BY REELING IT OUT ON A CABLE BEHIND THE AIRCRAFT TO A FIXED DISTANCE OR OFFSET 4HIS OFFSET IS CHOSEN SUCH THAT EVEN IF A MISSILE HITS THE DECOY  THE AIRCRAFT WILL NOT BE DAMAGED 4HE DECOY CAN EITHER BE POWERED BY THE AIRCRAFT VIA THE CABLE OR BE SELF POWERED "ESIDES PROVIDING POWER TO THE DECOY  THE CABLE CAN ALSO BE USED AS A DATA LINK TO CONTROL JAMMER OPERATION /NCE DEPLOYED  THE TOWED DECOY CAN BEGIN RADIATING JAMMING SIGNALS TOWARD THE MISSILE SEEKER 7HEN THE TOWED DECOY IS NO LONGER NEEDED  IT IS EITHER REELED IN OR JETTISONED 4HE MAJOR DRAWBACK WITH TOWED DECOYS IS THAT THEY MIGHT SEVERELY DEGRADE AIRCRAFT MANEUVERABILITY  !CCORDING TO THE PLATFORM  THE JAMMER CAN BE CLASSIFIED AS AIRBORNE  MISSILE 
 no. 105, Radar· Prt'St'lll  and Fut11re, London, Oct. 23-25, 1973, pp. 
 REPE AT ORBITS &OR EXAM 
  AND OTHERS   HUNDREDS OF PAPERS HAVE APPEARED DEALING WITH MEASUREMENTS OF SCATTERING AND RADAR APPLICATIONS -OREOVER  THE *0, !)23!2 HAS FLOWN AROUND THE WORLD  AND SEVERAL OTHER AIRBORNE 3!2S FOR REMOTE SENSING HAVE APPEARED IN VARIOUS COUN 
 MULATED AND AVERAGED PULSE 
 This generated a new set of diffraction coefficients that retained only the  edge terms, therefore excluding any surface terms. Ufimtsev’s PTD coefficients were  well behaved in almost all directions in space, but suffered one disadvantage: in order  to calculate the RCS of an arbitrary edged body, one had to sum all the PTD edge  contributions, plus all the PO and GO surface contributions. However, the procedure  is viable and has been well documented.40 Incremental Length Diffraction Coefficient. 
 The references174,175 present the  ch24.indd   51 12/19/07   6:01:13 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 17. Luo, Y.; Song, H.; Wang, R.; Xu, Z.; Li, Y. Signal processing of Arc FMCW SAR. 
 THE 
 ATTACHEDv WAVE "EYOND THE HORIZON  THE SURFACE WAVE IS THE DOMINANT CONTRIBUTOR  BUT AT SHORTER RANGES  ALL THREE MECHANISMS MUST BE TAKEN INTO ACCOUNT !CCORDINGLY  THE RELATIONSHIP BETWEEN I  TARGET ECHO STRENGTH AND II  THE RANGE AND ALTITUDE OF THE TARGET IS NOT A SIMPLE ONE -OREOVER  THE CALCULATION OF THE FIELD DISTRIBUTION IS COMPUTATIONALLY EXPENSIVE IF . 
 Thefirsttermrepresents theno-error powerpatternmultiplied bythesquareofthefractionofelements remaining and byafactorproportional tothephaseerror.'Theothertermdepends onboththeamplitude errorandthephaseerroraswellasthefraction ofelements remaining operative. Italso depends ontheaperture illumination, asgivenbythecurrentsimn•Notethatthissecondterm isindependent oftheangularcoordinates 8,c/J.Itcanbethoughtofasa..statistical omnidirec­ tional"pattern.Itcausesthefar-outsidelobes'to differinthepresen~ oferrorascompared to theno-error pattern.(Theno-error patternsidelobes generally dropoffrapidlywithincreasing. 1111' 1.1 I.C.1 RONI('AI I Y SIFI:RI:I> I'IIASEL) ARRAY ANTENNA IN RADAR 319  angle from broatlsitlc; tllereforc, beyotld sollle angle the radiation pattern will be donlitlatetl  by the error-produced sidelobes.) *The shape of the main beam and the near-in sidelobes are  relatively unamected by errors, although their magnitudes are modified. 
 These assumptions pro- vide a significant simplification in the calculation of the element impedance vari- ations. In addition, impedance measurements made in simulators correspond to the element impedance in an infinite array. In spite of the assumptions, the infinite-array model has predicted with good accuracy the array impedance and the impedance variations. 
 L. Stegall, “Multiple object tracking radar: System engineering considerations,” in Proc. Int . 
 1991  − K. Schmitt, E. Heidrich, W. 
 IZATION MODULATION  DOPPLER MODULATION  AND PULSE TIME MODULATION RANGE GLINT  4HE  BASIC MECHANISM BY WHICH THE MODULATIONS ARE PRODUCED IS THE MOTION OF THE TARGET   INCLUDING YAW  PITCH  AND ROLL  WHICH CAUSES THE CHANGE IN RELATIVE RANGE OF THE VARIOUS INDIVIDUAL ELEMENTS WITH RESPECT TO THE RADAR !LTHOUGH THE TARGET MOTIONS MAY APPEAR SMALL  A CHANGE IN RELATIVE RANGE OF THE  PARTS OF A TARGET OF ONLY ONE 
 CASE APPROXIMATIONS AND THE PRECARIOUS NATURE OF THE LOGICAL INFRASTRUCTURE OF THE "RAGG HYPOTHESIS IN MICROWAVE SCATTERING FROM A NATURAL SEA  IT IS QUITE POSSIBLE THAT FURTHER CAREFUL CONSIDERATION OF THE ACTUAL SCATTERING FEATURES PRESENT ON THE SEA SURFACE WILL IMPROVE OUR UNDERSTANDING OF SEA CLUTTER IN THE FUTURE )MPLICATIONS OF 3URFACE 'EOMETRY  4HE APPROXIMATIONS TO THE '"60 DIS 
 An important  feature of sequential lobing (as well as the other tracking techniques to be discussed) is that the  target-position accuracy can be far better than that given by the antenna beamwidth. The  accuracy depends on how well equality of the signals in the switched positions can be  determined. The fundamental limitation to accuracy is system noise caused either by mechani­ cal or electrical fluctuations. 
 F, no. 1, pp. 17–24, February 1999. 
 If 1000 elements (30 dB) are  used, the rms sidelobe level is 51 dB below the gain of the array. This is the effect of  only the random phase errors. The effects due to amplitude errors and failed elements  must also be included. 
 Remote Sens. Lett. 2015 ,12, 2463–2467. 
 LINE TECHNIQUE SIM 
 /-  -ATERIAL FROM )-/ PUBLICATIONS IS REPRODUCED WITH THE KIND PERMISSION OF THE  )NTERNATIONAL -ARITIME /RGANIZATION )-/   WHICH DOES NOT ACCEPT RESPONSIBILITY  FOR THE CORRECTNESS OF THE MATERIAL AS REPRODUCED IN CASE OF DOUBT  )-/S AUTHENTIC TEXT SHALL PREVAIL  4HE AUTHOR THANKS THE )NTERNATIONAL %LECTROTECHNICAL #OMMISSION )%#  FOR PER 
 LATITUDE IONOSPHERE MODEL v * 'EOPHYS 2ES  VOL    n    " +HATTATOV  - -URPHY  - 'NEDIN  4 &ULLER 
 CELLATION ARE INTIMATELY RELATED 2OUGHLY SPEAKING  THE DIFFERENCE IS THAT ONE PRODUCES A PATTERN WITH THE NULLS DOWN  ADAPTIVE ANTENNA FOR JAMMER CANCELLATION  AND THE OTHER  WITH THE NULLS UP  IE  PEAKS SUPERRESOLUTION OF JAMMERS  /NE LIMITING FACTOR OF SUPERRESOLUTION TECHNIQUES IS THAT THEY OFTEN REQUIRE THE  RECEIVED SIGNALS TO OBEY ACCURATE MODELS OF THE ARRAY MANIFOLD 4HIS CAN BE VIOLATED DUE TO PROPAGATION EFFECTS EG  SPATIAL SPREADING AND NONSTATIONARITY  AS WELL AS INSTRU 
 14 and 16. 6. Greene, C. 
 If the antenna beam dwells a time t0 in each direction subtended by the beam, the total scan time is ts = f0O/lV Substituting these expressions into Eq. (1.5) and noting that Et = ^av^O* . ^4 Fav Agg ts " max 4^kToFn(EIN0) ft u'" Thus for a volume search radar the two important parameters for maximizing range are the average transmitter power and the antenna aperture. 
 The trian- gular grid may be thought of as a rectangular grid where every other element has been omitted. The element locations can be defined by requiring that m + n be even. Calculations for the element-steering phases are greatly simplified by theWALF POWER BEAM WIDTH COS OCy UNIT CIRCLEcos ax . 
 (ILL    ( $ 'RIFFITHS ET AL  h-EASUREMENT AND ANALYSIS OF AMBIGUITY FUNCTIONS OF OFF 
 W. Morrow: The Fast Fourier Transform, IEEE Spectrum, vol. 4, pp. 
 39. D. C. 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 25.6  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 passbands extending right up to their stopband edges, so the widths of intervening  transition bands must be counted as part of two-sided signal bandwidth  B for purposes  of determining the Nyquist rate, as the filter output may contain components in these  transitions bands that could otherwise result in significant aliasing. Digital Downconversion (DDC). 
 and H. K. Hom: A Low-Loss Microstrip X-band Diode Phase Shifter, Jf74 Go11emment  Microcircuit Applications Conference Digest of Papers, pp. 
 CIAL SHIPS NORMALLY IN EXCESS OF  GT GROSS METRIC TONNAGE   WHERE RADAR FITMENT IS COMPULSORY AND HIGHLY REGULATED 7ORLDWIDE  THERE ARE ABOUT   OF THESE VES 
 CONTROL RADAR HAS SUFFICIENT SENSITIVITY TO DETECT A  SINGLE LARGE BIRD  SUCH AS A CROW  SEAGULL  OR VULTURE APPROXIMATE 2#3 OF  SQUARE METER  AT A RANGE OF   MILES )F THERE ARE  MANY SUCH BIRDS IN  THE RESOLUTION CELL OF THE  RADAR  THEN THE COMPOSITE 2#3 INCREASES 4EN LARGE BIRDS IN A RESOLUTION CELL WILL HAVE AN 2#3 OF  SQUARE METER 7HEN MULTIPATH REFLECTIONS OCCUR  SUCH AS OVER THE OCEAN WHEN THE RADAR BEAM IS CENTERED AT THE HORIZON  THERE CAN BE UP TO A  D" ENHANCEMENT OF THE 2#3 OF THE BIRDS  GIVING AN APPARENT 2#3 GREATER THAN ONE SQUARE METER TO THE FLOCK OF  BIRDS )F THERE IS  BIRD OR BIRD FLOCK  PER SQUARE MILE  THERE WILL BE ABOUT  BIRD RETURNS WITHIN  MILES OF THE RADAR 4ECHNIQUES USED TO COUNTER UNWANTED TARGETS ARE AS FOLLOWS  3ENSITIVITY TIME CONTROL 34#  USED FOR ELIMINATING LOW 2#3 TARGETS IN LOW 02&  RADARSTHAT IS  RADARS THAT HAVE NO RANGE AMBIGUITIES UNDER NORMAL OPERATION  %NHANCED HIGH 
 S. Raghavan, and M. J. 
 NATES RANGES FROM  TO  KM  WHEREAS  -(Z ILLUMINATES RANGES FROM  TO  KM WHEREAS  -(Z ILLUMINATES FROM  TO  KM (ENCE  THE FARTHEST EDGE OF THE FOOTPRINT NEED NOT INCREASE WITH FREQUENCY  DEPENDING ON THE PREVAILING IONO 
 If feedforward only is used,  only three or four pulses have to be gated out after moving the beam. The disadvan - tage of using feedforward for velocity response shaping is that an additional delay,  and therefore an additional transmit pulse, must be provided for each zero used to  shape the response. Figure 2.38 shows the velocity response and Z-plane diagram of a  feedforward-only, shaped-response, four-pulse canceler. 
 Laserradar.Thelargeattenuations experienced inclearairinthemillimeter (60GHz)and submillimeter regions arenotpresentintheinfrared andvisibleregionsofthespectrum. (Fig. 14.15). 
  
 SION TO A LOWER )& FOR DIGITIZATION OR BASEBAND CONVERSION )& FILTERING IS THE PRIMARY FILTERING USED TO DEFINE THE RECEIVER BANDWIDTH PRIOR TO !$  CONVERSION IN RECEIVERS USING EITHER )& SAMPLING OR BASEBAND CONVERSION )N )& SAMPLING RECEIVERS  THE )& FILTER ACTS AS THE ANTI 
 It includes a dual-frequency  water-vapor radiometer (WVR) at 22  and 37 GHz, data from which are  used to reduce the corresponding  propagation uncertainty to 1.9 cm.  †  Full deramp (or simply deramp) is standard terminology in space-based radar altimetry. It is known more commonly  to most radar engineers as the Stretch technique.FIGURE 18.9  The Geosat radar altimeter: The nadir- directed antenna (a reflector) is hidden inside of the  solar arrays. 
 The most realistic method for obtaining the radar cross section of aircraft is to measure  the actual target in flight. There is no question about the authenticity of the target being  measured. An example of such a facility is the dynamic radar cross-section range of the U.S. 
 Thusfar,areceiverwithonlyanoiseinputhasbeendiscussed. Next,consider asinc:-wave signalofamplitude AtobepresentalongwithnoiseattheinputtotheIFfilter.Thefrequency. 26 INTRODUCTION TO RADAR SYSTEMS  1 yeor  6 months  30 doys  2 weeks  l week  15 rnin  Figure 2.5 Average time between false alarms as a function of the threshold level I/, and thc receiver  bandwidth 8; (I/, is the mean square noise voltage. 
 If considerable amplitude fluctuation  noise were to appear at the conical-scan or lobe-switching frequencies, it could not he readily  eliminated with filters or AGC. A typical scan frequency might be of the order of 30 Hz.  Higher frequencies might also be used since target amplitude noise generally decreases with  increasing frequency. 
 2X SITE SEPARATION KM  n 0OWER AVERAGE  K7    0OWER PEAK  K7    &REQUENCY BAND -(Z  n 7AVEFORM LINEAR &- 
 The sum of the sixth power of the diameters per unit volume in Eq. (13.18) is called Z, the  radar reflectivity factor, or  Z= L D6 (13.19)  i  In this form Z has little significance for practical application. Experimental measurements,  however, show that Z is related to the rainfall rate r by  (13.20)  where a and hare empirically determined constants. 
 ZERO ALTITUDE  FOR THE FOLLOWING CONDITIONS 6 4   62    MS  C 4     C 2     AND K    M $IMENSION OF THE GRID ON THE BISTATIC PLANE IS ARBITRARY THAT IS  THE ISODOPS ARE INVARI 
 Lower data rates are allowable in midcourse than in terminal, providing an additional degree of freedom in the sys- tem design. Retransmission Guidance. 13*28~31 Retransmission guidance, also known as TVM (target-via-missile or track-via-missile), was initially conceived as a simpli- fication of missile-borne hardware, placing all the processing on the ground and making the seeker a simple repeater. 
 In fact, for grazing angles less than a few degrees and moderate to strong wind speeds,  observers have reported that at X band and at the higher sea states the horizontally  polarized returns can exceed the vertically polarized returns.1,32,33 The NRL 4FR system permitted transmission and reception on orthogonal polar - izations so that data could be collected for cross-polarized sea clutter. These returns  tended to have a weak dependence on grazing angle and were always smaller than  either of the like-polarized returns, lying in the cross-hatched region shown on  Figure 15.4. It is informative to compare measurements at different frequencies by different  investigators in different parts of the world under similar wind conditions. 
 (Similar  to Figure 1.4 in Skolnik.) • Coherent radar uses the same local oscill ator reference for transmit and receive. 20Coordinate Systems • Radar coordinate systems spherical polar: ( r,θ,φ) azimuth/elevation: (Az,El)  or  • The radar is located at the origin of  the coordinate system; the Earth's surface lies in the  x-yplane.   • Azimuth (α) is generally measured  clockwise from a reference (like a  compass) but the spherical system  azimuth angle (φ )is measured  counterclockwise from the xaxis. 
 FIELD CALIBRATION USES RADIATORS PLACED IN THE NEAR FIELD AROUND THE PERIPHERY OF THE ARRAY SEE &IGURE B   4HESE ADDITIONAL RADIA 
 However, in an air traffic control situation using ATCRBS,  targets would be interrogated at every scan and, consequently, either detections or  tracks could be integrated. Radar–DF Bearing Strobe Integration.  Correlating radar tracks with DF  (direction finding) bearing strobes on emitters has been considered by Coleman79 and  later by Trunk and Wilson.80,81 Trunk and Wilson considered the problem of associ - ating each DF track with either no radar track or one of m radar tracks. 
 WEIGHT CANCELERS REFERS  TO CANCELERS WITH THE N SINN O FD4  TRANSFER FUNCTION 4HE BLOCK DIAGRAM OF THIS TYPE OF  -4) CANCELER IS SHOWN IN &IGURE  &IGURE  TO &IGURE  REPRESENT TYPICAL VELOCITY RESPONSE CURVES OBTAINABLE FROM  ONE 
 Electronically scanned arrays are composed of very many parts and  include electronic circuitry to drive the phase shifters or switches that steer the beam.  The overall reliability of such arrays can be great; graceful degradation has been  claimed because the failure of as much as 10% of the components leads to a loss in  gain of only 1 dB. There is, however, a degradation of (low) sidelobes. 
 Oboe, which was born in Britain in 1941, consists  basically of two ground radar stations, A and B, which  both obtain responding pulses from the Oboe-controlled  aircraft. A small transmitter in the aircraft is pipped-off  on receipt of the ground pulses, many times a second.  Ground station A, known as the ‘cat’ or tracking  station, defines a marrow track at constant range from  the transmitter by sending out signals in dot-and-dash  form to the pilot. 
 A. Thompson, “RADARSAT-2 SAR modes development and  utilization,” Canadian J. Remote Sensing , vol. 
 TER MATCHED LOAD TO THE MAGNETRON AND  THEREFORE  GIVES A CLEANER 2& SPECTRUM 4HE LOW 
 A. Farina (ed.), Optimised Radar Processors , London: Peter Peregrinus, Ltd., 1987. 147. 
 24.48  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 Imaging Radar . There are two types of imaging radar that will be discussed:  synthetic aperture radar (SAR) and inverse SAR (ISAR). SAR. 
 Thus, the required number of amplitude bits in  the A/D converter as determined by the main-beam clutter is  NC N AD,am pdB dCEIL[fluct_ma rgin] ≥+ [(/ ) ]max B B 10 quanta 20log noise +     [ ] 6 (4.7) ch04.indd   26 12/20/07   4:52:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 (UYGENS MISSION WAS TO COMPLETE  FLYBYS OF 4ITAN  OF WHICH  WILL BE AT THE CLOSEST APPROACH OF LESS THAN  KM  OF WHICH  WILL HAVE MINIMUM ALTITUDES OF  ^ KM 4HE FIRST CLOSE FLYBY  WAS IN .OVEMBER   FROM WHICH THE FIRST RADAR IMAGES OF THE  SURFACE WERE COL 
 The telling ofplots bytelephone land line was thetechnique first used (Sec. 7.5) forthe transmission ofradar data from one point toanother. Substantial errors and delays areinherent inthis procedure. 
 THE 
 FUSION TARGETS AND OTHER COUNTERMEASURES THAT AN ATTACKER CAN LAUNCH TO ACCOMPANY THE REENTRY VEHICLE CARRYING A WARHEAD 4HE BASIC BALLISTIC MISSILE DEFENSE PROBLEM BECOMES MORE OF A TARGET RECOGNITION PROBLEM RATHER THAN DETECTION AND TRACKING 4HE NEED FOR WARNING OF THE APPROACH OF BALLISTIC MISSILES HAS RESULTED IN A NUMBER OF DIFFERENT TYPES OF RADARS FOR PERFORMING SUCH A FUNCTION 3IMILARLY  RADARS HAVE BEEN DEPLOYED THAT ARE CAPABLE OF DETECTING AND TRACKING SATELLITES ! RELATED TASK FOR RADAR THAT IS NOT MILITARY IS THE DETECTION AND INTERCEPTION OF DRUG  TRAFFIC 4HERE ARE SEVERAL TYPES OF RADARS THAT CAN CONTRIBUTE TO THIS NEED  INCLUDING THE LONG 
 The short  pulse, with its high-frequency content, characterizes the fine, detail of the target. Although this  can be used as a means of target classification, it has been suggested that the usual short-pulse  radar does not obtain important information about the target since its waveform does not  contain the lower frequencies.53-55•62 The lower frequencies that are suggested as being im­ portant are those corresponding to wavelengths from half the target size to wavelengths about . 438 INTRODUCTION TO RADAR SYSTEMS  ten times the target dimensions. 
 7.1,  May, 1974.  149. O'Donovan, P. 
 T op. Appl. Earth Obs. 
 The HF radar repre­ sents a unique tool for measurin~ sea conditions at a distance. The cost of a radar to measure  sea conditions can be considerably less than the cost of an HF radar to detect aircraft. It is  interesting lo note that the development of such a capability was originally not as an attemrt  to learn more ahout the sea, but was a byproduct of attemrts to improve the detection of  targets in a sea-clutter background. 
 M..andP.A.Mcinnes: OntheSpecifkation ofanAntenna Pattern foraSynthetic Aperture Radar.11Itt'fllelciOlwl ('011/('1'('11("(' R..tIJt1R-77. pp.391395.Oct.252X.1977.lEE(London) Conf. Puo/..no.155. 
 In CFA chains, leveling is far simpler because excess drive power is harmless (it just feeds through and adds to the output),15 and it is only necessary to ensure that there is always adequate drive power. Stability Budgets. In a multistage chain, each stage must have better stability than the overall requirement on the transmitter, since the contributions of all stages may add. 
 The full sampled-signal spectrum is obtained by laying copies of this page  end-to-end, as shown in Figure 25.3 c, producing copies of the 0 to B portion of the  sampled signal spectrum at B intervals. Figure 25.4 shows the result of sampling below the Nyquist rate. Figure 25.4 a  shows the same bandlimited signal as the previous example, but this time it is sampled  at some rate that is less than Nyquist rate B. 
 Development of 10 cm ASV was undertaken separately in the twocountries. However, early work in the USA, starting in 1941, was the result of a close collaboration with British scientists working at the Radiation Laboratory. It was decided to concentrate on a design for the Liberator aircraft, which ﬁtted Coastal Command requirements for a long-range aircraft, although it was not certain at that time whether the Air Ministry would release Liberators for that role. 
 The five-horn feed is selected because of the simplicity of the comparator which requires only two magic (or hybrid) Ts for each polarization. The sum and difference signals are provided for the two linear-polarization components and, in an AN/FPQ-6 radar, are combined in a waveguide switch for selecting . FIG. 
 The IRACS is a coherent range-gated pulsed doppler radar which searches for, acquires, and tracks other orbiting objects and provides the spatial measurement data needed to perform rapid and efficient rendezvous with those objects. The IRACS performs both radar and communications functions for the STS. In the pulsed doppler radar mode it performs the rendezvous function just de- scribed. 
 INDUCED SIGNAL 3INCE THE TIME AT WHICH THE TARGET UNDER TRACK ACTIVATES 2'0/ IS UNKNOWN TO THE TRACKING ALGORITHM  THE LATTER MUST FIRST RECOGNIZE THAT 2'0/ IS ACTIVE AND THEN IMPLEMENT AN APPROPRIATE ! 
 This result proves the validity of our method. percentage =1−mean/parenleftBigg|ISR−Improved |To p |ISR−Ionosonde |To p/parenrightBigg . (13) Figure 5. 
 DOMAIN RESPONSES FOR THIS FILTER AS THE ANTENNA SCANS  PAST A POINT OF CLUTTER  SUCH AS A WATER TOWER 4HIS FIGURE SHOWS THE INPUT TO THE ELLIPTIC FILTER AND THE RESIDUE OUTPUT ! GAUSSIAN ANTENNA PATTERN IS ASSUMED IN THIS FIGURE 4HE CALCULATED IMPROVEMENT FACTOR FOR THE SEQUENCE SHOWN TOTAL CLUTTER POWER INTO THE FILTER DIVIDED BY TOTAL RESIDUE POWER OUT OF THE FILTER  NORMAL IZED BY THE NOISE GAIN OF  THE FILTER  IS  D" ! SINX X ANTENNA PATTERN IS ASSUMED FOR THE FOLLOWING THREE FIGURES  BUT THE LESSONS  TO BE GAINED FROM THESE FIGURES IS ESSENTIALLY INDEPENDENT OF THE ASSUMED BEAM SHAPE &IGURE  SHOWS THE FILTER RESPONSE IF THE TRANSMITTER STARTS RADIATING JUST AS A NULL OF THE ANTENNA PATTERN PASSES THE POINT OF CLUTTER 4HE INDIVIDUAL SAMPLES OF RESIDUE ARE  OR MORE D" BELOW THE PEAK CLUTTER RETURN 4HE IMPROVEMENT FACTOR FOR THIS SEQUENCE IS  D" &)'52%   %LLIPTIC FILTER #7 RESPONSE AND RESPONSE TO WEATHER WITH  R     AND  MS RMS  SPECTRAL SPREAD$ !! " !   $  !! " !   !   !                   
 The presence of the diode limiter following the TR tube considerably reduces the spike  leakage, increasing the life of the device itself as well as the receiver front-end it is supposed to  protect. The passive TR-limiter, however, has a higher insertion loss than the TR tube but 11  generates no excess noise because it does not employ a keep-alive discharge. Its recovery time  is superior to the conventional TR tube, but inferior to the diode limiter acting alone or the  ferrite diode limiter.40  The passive TR-limiter has low leakage over a wide range of input power. 
   &OR A  
 RATED FREQUENCIES  THE BLIP 
 J. Appl. Phys.. 
 BEAM ANTENNAS  WHOSE FOOTPRINTS WERE ORIENTED AT  n  n  AND n WITH RESPECT TO  THE SATELLITE TRACK 4HE TWO OUTER ANTENNAS ARE  
 This procedure, while reducing the number of phase shifters, generally results in  lower gain and higher far-out sidelobes than would be produced by an amplitude taper.  A space-fed renectarray with an offset feed is shown in Fig. 8.23. 
 Steinberg, “High angular microwave resolution from distorted arrays,” Proc. Int. Comput. 
 This has sometimes been called interrupted CW (ICW).3 A high PRF is defined as one which is unambiguous in doppler. Thus when the receiver selects the central line, the spectrum is identical to the CW case. The radar receiver must be protected during transmission (duplexing and/or gating). 
 STANT BY WHICH A RECEIVER OUTPUT INDICATION MAY BE CONVERTED TO AN ABSOLUTE 2#3 VALUE . £{°Ón  2!$!2 (!.$"//+  #OMMON CALIBRATION TARGETS INCLUDE METAL SPHERES  RIGHT CIRCULAR CYLINDERS  FLAT PLATES  AND  CORNER REFLECTORS 4HE RADAR CROSS SECTIONS OF THESE OBJECTS MAY BE CALCULATED BY USING THE EXPRESSIONS GIVEN IN 3ECTION  "ECAUSE  RESIDUAL  BACKGROUND  REFLEC 
 17.18  17.3 Time Gating  ............................................................  17.19  Transmitted-Pulse Suppression  .........................  17.19 Range Gating  .................................................... 
 UP  AND   &- 
 The intermediate-frequency (IF) input to the pulse com- pressor can easily be shown to be I T<A / 7Ae{F = A rectl t - — rect It - —I \ 1J \ 1R/ cos [2ir(f0 +fd- fR)(t - T1n) + Tr(ain - aR) (t - Tin)2 + 21TOLa(T* - Tin)(f ~ T1n) + l|l] The resultant waveform is a reduced-frequency-slope linear-FM waveform with a target-range-dependent frequency offset riding on the doppler-shifted IF carrier frequency. Note that the frequency slope of the received waveform will be mod- ified by the target's velocity. For the special case where the two frequency slopes are equal, the IF . 
 Itisclear that Gcould not begreater than 1inevery direction, and infact theaverage ofGtaken over thewhole sphere must bejust 1. Usually weareinterested inantennas forwhich Ghas avery pro- nounced maximum inone direction, that istosay, antennas which 1Thelimitation implied istodistances greater than all/X, where disthewidth of theantenna aperture andxthewavelength. Atdistances Rlessthan this(less than 366ft,forexample, forx=3cm,d=6ft),theintensity does notfalloffas1/RJ. 
 Thus this approach would be suitable for radars whose targets are at long range, such  as satellite surveillance or BMD (Ballistic Missile Defense). On reception, a separate receive  beam must be generated for each direction of transmission. In a surveillance application this  could require the complication of some sort of beam-forming. 
 .. .. .. 
 29. Meyer, F.J.; Nicoll, J.B. Prediction, detection, and correction of Faraday rotation in full-polarimetric L-band SAR data. 
 SIDELOBE ANTEN 
 TO 
 5. Slicrriian. J. 
 ch15.indd   41 12/15/07   6:17:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter. 
 The  measurement process assumes that the pulse is associated with the second tr ansmitted pulse and  declares a much reduced range for the target. This is called range ambiguity and occurs where  there are strong targets at a range in excess of the pulse repetition time. The pulse repetition time  defines a maximum unambiguous range. 
 Software tools con - vert this high-level description of the processor to a file that is sent to the device to  tell it how to configure itself. High-performance FPGAs store their configuration in  volatile memory, which loses its contents when powered down, making the devices  infinitely reprogrammable. FPGAs allow the designer to fabricate complex signal processing architectures very  efficiently. 
 Î°£n  2!$!2 (!.$"//+  Î°ÇÊ - 1 / 
 ARRAY RADAR TRACKS MULTIPLE TARGETS BY MULTIPLE INDEPENDENT BEAMS  FORMED BY THE SAME ARRAY APERTURE  THAT ARE ALLOTTED TO DIFFERENT TARGETS 4HIS SUBSECTION IS LIM 
 If there is no doppler frequency shift, the beat note (difference  frequency) is a measure of the target's range and fb = f,, wheref, is the beat frequency due only  to the target's range. If the rate of change of the carrier frequency isj,, the beat frequency is  In any practical CW radar, the frequency cannot be continually changed in one direction  only. Periodicity in the modulation is necessary, as in the triangular frequency-modi~lation  waveform sllown in Fig. 
 (a) Vertical polarization.  (I,) Ilori7ontal polari7alion. Two curves are sl~own for Phoenix: one is for a sample size of 1000 and  corresponds to the downtown area. 
 113. R. K. 
 JAMMING POWER BY A FACTOR PROPORTIONAL  TO THE ANTENNA GAIN  'T (ERE  IT IS NOTED A BASIC DIFFERENCE BETWEEN SURVEILLANCE AND  TRACKING RADAR THE DETECTION RANGE OF A TRACKING RADAR IMPROVES AS THE FREQUENCY IS INCREASED FOR A FIXED 
 (See also Chap. 6 of ref. 19.)  62. 
 13.13 RADIATION PATTERN NULLING Phased array antennas can be designed to have deterministic antenna patterns or adap - tive antenna patterns. When no interfering signals are present, a phased array antenna  with a deterministic antenna pattern will typically utilize phase weights that provide a  linear phase front over the array face and amplitude weights that produce the desired  sidelobe levels. The antenna performance can be characterized by parameters such  as antenna beamwidth, gain, and peak and RMS sidelobe levels. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers.  RADAR RECEIVERS  6.436x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 Hilbert Transformer. 
 Itwasalso foundthattheoperator's detection capability wasmaximum whenBT~1,whereB=IF bandwidth andT=pulsewidth,asisconsistent withtheanalysis ofSec.10.2. ThedetectabilityofatargetechoonaCRTdisplaydepends onsuchfactorsasthesize andbrightness oftheCRTspot,thenoisebackground, pulserepetition frequency, antenna rotation rate,typeofphosphor, anditsdecaycharacteristics, thesizeofthedisplay,andthe colorandintensity oftheambient illumination. Theeffectofmostofthesefactorshasbeen determined empirically.31.51.62 Thenamepipology issometimes appliedtotheartofdesigning andoperating theradardisplaysoastooptimize theoperator's abilitytodetecttargetpips.(A targetpipisalsocalledablip.)Ithasalsobeenfoundfromexperience thatanoperator should not,ingeneral, berequired toperform hisdutiesformorethanone-half houratonesitting. 
 The displays on the indicator unit comprised a 5 inch diameter PPI and the 2 inch diameter height tube. The main controls available to the operator were for their respective brightness. There were pre-set controls for focus, contrast and shift. 
 SCALE CIRCULATION  STUDIES  IS *ASON 
 TROLLED MOUNTING POINTS 4HIS SETS UP A SYSTEMATIC ERROR IN THE FORM OF PERIODIC CUSPS SEE &IGURE   4HESE ERRORS TYPICALLY CAUSE PATTERN GRATING LOBES BECAUSE THESE ERROR CUSPS ARE NORMALLY SEVERAL WAVELENGTHS APART  4HE GRATING LOBES ARE EASILY RECOGNIZABLE BASED ON THEIR              
 A block diagram illustrating the principle of the FM-CW radar is shown in Fig. 3.11. A  portion of the transmitter signal acts as the reference signal required to produce the beat  frequency. 
 ( a)α=0.0204, Γ0/υ=10π, the maximum velocity of the vortex current ﬁeld Vmax=0.68 m/s , and the rotation direction of the vortex current ﬁeld is clockwise. ( b)α=0.0272, Γ0/υ=10π,Vmax=1m / s , and the current ﬁeld is clockwise. ( c)α=−0.0272, Γ0/υ=10π,Vmax=1m / s , and the current ﬁeld is anticlockwise. 
 M., and J. D. Lawson: The Theoretical Precision with Which an Arbitrary Radiation  Pattern May Re Ohtained with a Source of Finite Size, J. 
 The ferrite circulator4 7 is a three-or four-port device that  can. in principle, offer separation of the transmitter and receiver without the need for the  conventional duplexer configurations of Figs. 9.5 to 9.7. 
 Aeronaut. Electron .,  May 12–14, 1958, pp. 286–290. 
 It is important to note that sub-refraction may involve an element of danger to shipping where small vesselsand ice may go undetected. The ofﬁcer in charge of the watch should beespecially mindful of this condition and extra precautions be administeredsuch as a reduction in speed and the posting of extra lookouts.Super-refraction The distance to the radar horizon is extended. In calm weather with no turbulence when there is an upper layer of warm, dry air over a surface layerof cold, moist air, a condition known as SUPER-REFRACTION may occur(see ﬁgure 1.9). 
 ON  2#3 OF A FLAT PLATE HAVING THE PLANFORM SHOWN IN &IGURE   FOR WING LEADING EDGES  K IN LENGTH 4HE INCIDENT ELECTRIC FIELD  WAS IN THE PLANE OF THE PLATE . £{°Óä  2!$!2 (!.$"//+  POWER OF THE FREQUENCY OF THE INCIDENT WAVE "ECAUSE THE METHOD OF MOMENTS IS  QUITE WELL SUITED TO THE SOLUTION OF 2AYLEIGH 
 BAND SOLID 
 7.5, involving thecontrol offormations offighter interceptors from acentral station atwhich radar data were assembled and assessed, were firmly established procedures. Inthat year two things happened which gave rise tothetechnique ofclose con- trol asitwas practiced bythe FDp’s ofthe -herican TAC’S inthe continental phase oftheIluropean war. Ayoung .Imerican officer, lyho was \vorking with the R.\F asamember ofthe Electronics Training Group sent totheunited I1ingdom soon after the~nited States went to war, conceived theidea ofcontrolling formations ofday fighters directly from the information available athisradar station alone. 
 interference with STAP algorithms.  Application to live data acquired with a ground-based phased-array radar demonstrator,” Proc.   of 2004 IEEE Radar Conf ., Philadelphia (USA), April 26–29, 2004, pp. 
 In  addition to the 3dB gain in performance achieved by using two transmitters in parallel, the use of  two separate frequencies improves the radar performance by decreasing the fluctuation loss by  (typically) 2.8dB (see Tables 2 and 3) .   6 2 2 3 1522 4 4max 310 1900 0.11 14 4 5 10Wm W2106.8 67km 4 .6tx t MDS sPGR PL                The result expressed in nautical miles is 57.7 NM.   In order to increase detection probability of frequency diversity radar two pulses of different  frequency are radiated one after another at very short intervals. 
 Separate transmit and receive antennas were used in the ﬁrst systems and both broadside and homing systems were installed on most aircraft. The display was in the form of an A scope,also known as an L-scope, with range along the vertical axis and returns from left hand antennas displayed as de ﬂections to the left and from right hand antennas as deﬂections to the right, so giving an indication when homing of bearing from their relative amplitude. Horizontal polarisation was used. 
 5, pp. 3–6,   May 2006. 20. 
 WAVE STRUCTURE 7ITH THE  USE OF LIQUID COOLING  IT IS CAPABLE OF  -7 PEAK  POWER OVER A  -(Z BANDWIDTH )TS DUTY CYCLE IS   WITH A GAIN OF  D"  AND A  §S PULSE WIDTH 4HIS 474 WAS ORIGINALLY DESIGNED TO BE USED INTERCHANGEABLY WITH THE POPULAR 6! 
 NAS DO NOT CAUSE TIME SIDELOBES  AND THE RECEIVER DOES NOT DISTORT THE RECEIVED SIGNAL 4IME $OMAIN  -OST COMMERCIALLY AVAILABLE '02 SYSTEMS USE SHORT PULSES OR  IMPULSES SUCH AS THE 2ICKER WAVELET  AS SHOWN PREVIOUSLY IN &IGURE  4HE HIGH 
 Airborne radar may be used to detect  other aircraft, ships, or land vehicles, or it may be used for mapping of land, storm avoidance,  terrain avoidance, and navigation. In space, radar has assisted in the guidance of spacecraft  and for the remote sensing of the land and sea.  The major user of radar, and contributor of the cost of almost all of its development, has  been the military: although there have been increasingly important civil applications, chiefly  for niaririe and air tiavigation. 
 278. Sensors 2019 ,19, 1154 The remainder of this paper is organized as follows: in Section 2, basic procedures of moving ship refocusing in SAR images is presented; ISAR processing based on fast minimum entropy phase compensation is elaborated in Section 3. In Section 4, experiments based on real SAR images are performed and the conclusions are presented in Section 5. 
 The re- ceived frequency, indicated bythe dotted line, isasimilar curve but (a)displaced tothe right bytime delay resulting from transmission tothetarget and back and (b)dis- placed vertically bydoppler shift. Ifnow the difference between the transmitted and received frequen- cies ispassed through alow-pass filter whose pass band includes fre- quencies ashigh asthe maximum doppler frequency, there will, in general, belittle signal output be- cause the difference frequency will begreater than the doppler fre- quency over the majority oftheI FIG.5.14.—The fullcurve intheupper graph shows theinstantaneous transmitter frequency asafunction oftime; thedotted curve shows thereceived signal; andthe dashed curve, thebeat between thetwo. Thelower curve shows thesame quantities when 2r/c =nf,,inwhich case thebeat frequency isconstant atthedoppler value. 
 It may also be noted that the clutter extent in ASV Mk. VII is expected to be greater than for ASV Mk. VI, although this was not observed in the trials results. 
 Gardiner. vol. 3, pp. 
 ARRAYS THAT GENERATE SUM AND DIFFERENCE CHANNELS #  $    "   " "       !#     "    #  $    "     #  $     "     #  $     "     " "              "     
 FORMS TO MAXIMIZE THE ENERGY ON TARGET AND PROVIDE LONG DETECTION RANGE &ORWARD 
 ING COMPLEX OFTEN OVER MOST OF THE MICROWAVE BAND   3OMETIMES  MULTIPLE FUNCTIONS  CAN BE PERFORMED SIMULTANEOUSLY IF A COMMON WAVEFORM IS USED 4HE ANTENNA APERTURE USUALLY HAS MULTIPLE PHASE CENTERS ENABLING MEASUREMENT FOR  3PACE 
 PLAY IN hPORTRAITv FORMAT IN ORDER TO GET MAXIMUM LOOK 
 32.Croncy. J.:ClullcronRadarDisplays, Wireless Ellgr.,vol.33.pp.83--96,April,1956. 33.Wylic.F.J.:"TheUseofRadaratSea,"HollisandCarter,Ltd.,London, 1968. 
 18.45  18.9 Other External Causes of Error  ..............................  18.46  Multipath  ...........................................................  18.46 Crosstalk Caused by Cross-Polarized  Energy  ............................................................ 
 The general planar array characteristics are readily obtained from a few simple  equations that are given here but discussed later in greater detail. With the elements  spaced by l /2 (l = wavelength) to avoid the generation of multiple beams (grating  lobes), the number of radiating elements N for a pencil beam is approximately related  to the beamwidth by  N B≈10000 2, ( )q   qBN≈100  where qB is the 3-dB beamwidth in degrees. The corresponding antenna gain, when the  beam points broadside to the aperture, is  G0 ≈ p Nh ≈ p NhLha  ch13.indd   2 12/17/07   2:38:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 P. Ferrazzoli et al., “The potential of multifrequency polarimetric SAR in assessing agricultural  and arboreous biomass,” IEEE Trans. on Geosc. 
 TION WITH AN ADAPTIVE FILTER  ELECTRONICALLY DISPLACING THE ANTENNA PHASE CENTER %LECTRONICALLY  $ISPLACED  0HASE  #ENTER  !NTENNA  &IGURE  A SHOWS THE  PULSE 
 Onreceiving the echo at 123.5 microseconds after the instant of the pulse, thereceiver sends a video signal to the indicator which in turn acts to intensifyor brighten the electron beam at the point in its sweep at 123.5microseconds,i.e.,at10milesonthetimebase.Thisbrighteningofthetraceproduced by the sweep at the point corresponding to the distance to thetargetinconjunctionwiththepersistenceofthePPIproducesavisibleimageof the target. Because of the pulse repetition rate, this painting of an imageon the PPI is repeated many times in a short period, resulting in a steadyglow of the target image if the target is a reasonably good reﬂector. In navigational and collision avoidance applications of radar, the antenna and the beam of r-f energy radiated from it are rotated at a constant rate,usually about 10 to 20 revolutions per minute in order to detect targets allaroundtheobserver’sship.Intheprecedingdiscussionofhowatargetimageis painted on the PPI, reference is made only to radial deﬂection of theelectron beam to produce the sweep or time base. 
 Ryzhkov and D. Zrnic, “Assessment of rainfall measurement that uses specific differential  phase,” J. Appl. 
 ATTENUATION 
 However, as has been emphasized in Sec. 2.2, in the numerator of the range equation the uncompressed pulse length must be used along with the actual radiated pulse power, P1.) Since the range equation (2.6) and those subsequently derived from it incor- porate the assumption of Eq. (2.4) (namely, that the noise output power of the receiver is equal to /CT^nG0), the definition of Bn—the noise bandwidth—must conform to that assumption. 
 38. K. Tomiyasu, “Conceptual performance of a satellite-borne, wide swath synthetic aperture radar,”  IEEE Transactions on Geoscience and Remote Sensing , vol. 
 2.1  Conventions  ......................................................  2.2  Range Prediction Ph ilosophy  .............................  2.2  Historical Notes  ................................................. 
 NAS AT SLIGHTLY DIFFERENT ALTITUDES AND COMPARED  COHERENTLY TO OBTAIN FINE 
 778-807. May, 1959.  50. 
 4(% 
 NOISE RATIO ON RECEIVE 4HE IMPACT OF THE REQUIREMENT FOR HIGH RADI 
 The ideal pattern shaping for a high-mounted VTS antenna requires a sharp cut-off  above the horizon and a tapered pattern below. Energy directed above the horizon  increases precipitation clutter and also reduces the antenna gain. At angles below the  horizon, the gain should nominally follow a cosecant squared power law. 
 MANCE CURVES HAVE BEEN LIMITED IN ALMOST ALL EXAMPLES TO THE CASE OF LOW SOLAR ACTIVITY  SINCE  IN GENERAL  THIS IS THE  MOST DIFFICULT TIME 4HE HIGHER  FREQUENCY AVAILABILITY AND  PERFORMANCE AFFORDED AT HIGH SOLAR ACTIVITY IS ILLUSTRATED IN &IGURE   WHICH TREATS THE CASE OF *ULY  54# FOR 33.    !NALYSIS OF PERFORMANCE ESTIMATION CURVES FOR ALL COMBINATIONS OF I  THE FOUR  SEASONS  II  DAY AND NIGHT  AND III  HIGH AND LOW SOLAR ACTIVITY  REVEALS CONSISTENT  BEHAVIOR I  3UMMER SHOWS MUCH GREATER LOSSES THAN WINTER II  %XCEPT FOR SUMMER  NIGHT LOSSES ARE ONLY SLIGHTLY LESS THAN DAY LOSSESIII  .IGHT NOISE IS MUCH GREATER THAN DAY NOISEIV  &OR A SPECIFIC RANGE  OPTIMUM FREQUENCIES VARY BY  4HIS /4( PERFORMANCE PRESENTATION FORMAT CAN BE USED TO DECIDE ON THE ANTENNA  PATTERNS AND POWERS REQUIRED FOR SPECIFIC TARGETS AND MISSIONS  OR IT CAN BE USED TO  EXHIBIT PERIODS OF ENHANCED OR DEGRADED PERFORMANCE FOR AN EXISTING DESIGN  &)'52%   2ADAR PERFORMANCE ESTIMATE FOR *ULY  54#  33.     .   (& /6%2 
 ch18.indd   66 12/19/07   5:15:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 PALSAR’s antenna consists of 80 solid-state T/R modules  distributed on four panels whose deployed dimensions are 3.1 m by 8.9 m, vertical  and horizontal, respectively. Spacecraft velocity and antenna length dictate a lower  bound on pulse repetition frequency, which for PALSAR spans 1.5 kHz–2.5 kHz,  depending on mode. Peak transmitted power is ∼2 kW, twice that of the Seasat SAR. 
 The individual pencil beams have a higher gain  than a fan-beam antenna, and can provide a larger number of hits at a higher data rate than  can a 30 radar with a single scanning beam in elevation. .)  Scanning pencil beam. Three-coordinate, or 30, information can be obtained on each rotation  of the radar by electronically scanning a single pencil heam in elevation while mechanically  rotating the antenna in azimuth. 
 158. B. Ramsay et al., “ Use of RADARSAT data in the Canadian ice service,” Canadian Journal of  Remote Sensing , vol. 
 The energy storage device might be made up of  capacitors, inductors, or some combination of the two as in pulse-forming networks.  The energy in the energy storage device is discharged by a very capable switch. The line-type modulator  uses a delay line or a pulse-forming network (PFN) as the  energy storage element. 
 PAIR ESTIMATION TECHNIQUE AND A GAUSSIAN 
 This constraint is that the radar is  required to search a specified volume of space within a specified time. Let n denote the angular  region to be searched in the scan time ts. (For example, Q mjght represent a region 360° in  azimuth and 30° in elevation.) The scan time is ts= t0n;n0, where t0 is the time on target=  11/JP, and n0 is the soi id angular beam width which is approximately equal to the product of the  azimuth beamwidth 80 times the elevation beamwidth 8e. 
 . Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  133     Design the receiver/processor using a close approximation to a Matched fi lter in order  to min imize mismatch loss.   Place most (or all) of the amplitude weighting in the analog receiver portion of the  system. 
 TORS AT BOTH APERTURES 4HE ANTENNA IS SHOWN IN &IGURE  )T IS MOUNTED ON A VEHICLE AND FOLDS FLAT FOR TRANSPORTATION&)'52%   *OINT 34!23 ANTENNA AND AIRCRAFT #OURTESY OF .ORTHROP 'RUMMAN #ORPORATION  &)'52%   0!42)/4 MULTIFUNCTION PHASED ARRAY #OURTESY  OF 2AYTHEON #OMPANY  . 
 SIN  COS   COS;   =P P  EE      9NN NNIS 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.44  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Measurements with suitable averaging in frequency or illumination angle demonstrate  that snow-covered surfaces scatter essentially uniformly except for the effects of the  multipath fading. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter.  SEA CLUTTER  15.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 smaller than that of “clean” water. 
 237-248, 4th qtr.,  1973.  15. Fletcher, R.H., Jr., and D. 
 59-267, April 1960. 47. Swerling, P.: Probability of Detection for Fluctuating Targets, IRE Trans., vol. 
 In missile-range instrumentation, the tracking-radar output is used to measure the trajectory of the missile and to predict future position. Tracking radar which computes the impact point of a missile continuously during flight is also impor- tant for range safety. Missile-range instrumentation radars are normally used with a beacon to provide a point-source target with high signal-to-noise ratio. 
 The mission naturally creates the need for an air- to-surface mode suite7,9 for fighter radar, as shown in Figure 5.11. Each general cat - egory of operation contains modes primarily for that function, but modes will often  be invoked during other parts of the mission. Within each mode shown in Figure 5.11,  there is optimization for the particular combination of altitude, range to the target,  antenna footprint on the Earth’s surface, relative target and clutter doppler, dwell time  available, predicted target statistical behavior, transmitted frequency, and desired reso - lution. 
   ,ONDON  /CTOBER n    PP n  - ) 3KOLNIK  ' ,INDE  AND + -EADS  h3ENRAD !N ADVANCED WIDEBAND AIR SURVEILLANCE RADAR v  )%%% 4RANS  VOL !%3n  NO   PP n  /CTOBER   " , ,EWIS  & & +RETSCHMER  AND 7 7 3HELTON   !SPECTS OF 2ADAR 3IGNAL 0ROCESSING   .ORWOOD   -! !RTECH (OUSE  )NC    . ,EVANON AND % -OZESON  2ADAR 3IGNALS  .EW 9ORK *OHN 7ILEY  3ONS  )NC   ' 0ETROCCHI  3 2AMPAZZO  AND ' 2ODRIGUEZ  h!NTICLUTTER AND %##- DESIGN CRITERIA FOR A LOW  COVERAGE RADAR v 0ROC )NT #ONF 2ADAR  0ARIS  &RANCE  $ECEMBER n    PP n  6 ' (ANSEN AND ! * :OTTL  h4HE DETECTION PERFORMANCE OF THE 3IEBERT AND $ICKE 
 It is obvious that both the integration time and azimuth resolution signiﬁcantly increase with kω. When|kω|=0.007 rad/s, the integration time reaches 86.49 s compared to 10.67 s for stripmap ( |kω|=0 rad/s), meanwhile the theoretical resolution will increase to less than 0.75 m. As a consequence of beam scanning, the ionospheric incident angle of beam center varies within the acquisition time, whereas the traditional scintillation simulator cannot accurately simulate the beam scanning of sliding spotlight mode. 
 The resolution capability of the log detector which uses only the half of the ref- erence cells with the lower mean is shown in Fig. 8.22. The probability of resolv- ing two equal-amplitude targets does not rise above 0.9 until they are separated in range by 2.5 pulse widths. 
 RETURN AREA .2!  NOT INCLUDING THERMAL NOISE  DIVIDED BY THE  AVERAGE IMAGE INTENSITY IN A RELATIVELY BRIGHT SURROUNDING AREA IN PRINCIPLE NOT INCLUD 
  
 One method of increasing the bandwidth  of a pulse of duration T is to provide internal modulation. The ambiguity diagram for a  frequency-modulated pulse is shown in Fig. 11.12. 
 However, the nonsymmetrical waveform retains some of the range-doppler cross coupling of the linear-FM waveform. The disadvantages of the nonlinear-FM waveform are (1) greater system com- plexity, (2) limited development of nonlinear-FM generation devices, and (3) the necessity for a separate FM modulation design for each amplitude spectrum to achieve the required sidelobe level. Because of the sharpness of the ambiguity function, the nonlinear waveform is most useful in a tracking system where range and doppler are approximately known. 
 the noise that accompanies the transmitter leakage signal rather than by any damage caused  by high power.5 For example, suppose the isolation between the transmitter and receiver were  si~cli that 10 mW of leakage signal appeared at the receiver. If the rnini~num detectable signal  were 10-l3 watt (100 dB below 1 mW), the transmitter noise must be at least 110 dR  (preferably 120 or 130 dB) below the transmitted carrier.  The transmitter noise of concern in doppler radar includes those noise components that  lie within the same frequency range as the doppler frequencies. 
 Problems, Itrtc~rtrlrtiotrcrl Cot!/:- otr Rtrdar----Prrset~t otrd  1~rrrrtr.c~. Oct. 23 25, 1973. 
   PP n   -ARCH   7 * #APUTI  h! TECHNIQUE FOR THE TIME 
 3.18. The curve is mirrored  becailsc of the periodicity of D. The nulls in the curve suggest that echoes from certain ranges  can be suppressed if ttie modulation parameters are properly selected. 
 The transmitter-receiver unit contains themagnetron, themodulator and itspower supply, the duplexer, the TR switch, the mixer, and the local oscillators, aswell asamotor-driven time-delay switch formodulator turn-on, and atrigger amplifier forthe modulator. The receiver strip, TABLE 15.2,—DETAILED Specifications OFTHE ANT/APS-10 Total weight ofunits andmountings. ., 124* lblesscables Primary power required Alternating current. 
 NOISE 
 19 or" Radar Handbook," M. I.  Skolnik (ed.), McGraw•Hill Book Co., New York, 1970. 
 GETS PRESENT AT DIFFERENT DOPPLERS  THE TWO FREQUENCIES OBSERVE D DURING THE &- PERIOD  CANNOT BE UNAMBIGUOUSLY PAIRED WITH THE TWO FREQUENCIES OBSERVED DURING THE NO 
 NOISE RATIO *.2  VALUE  THE BLANKING THRESHOLD  &  AND  THE GAIN MARGIN  A   '!'SL OF THE AUXILIARY ANTENNA WITH RESPECT TO THE RADAR ANTENNA  SIDELOBES II  4HE PROBABILITY  0&! OF FALSE ALARM  WHICH IS THE PROBABILITY OF ASSOCIAT 
 At 10 km altitude C; is approxi­ mately 10 O m 2 -'. An S-band radar with one degree beamwidth and 1 11s pulsewidth  viewing a turbulent medium with 11 = 10-10 m-1 yields a radar cross section at 10 km of  about J x 10-4 m2. Thus. 
 Radar is also used for terrain avoidance  and terrain following. Although they may not always be thought of as radars, the radio  altimeter (either FM/CW or pulse) and the doppler navigator are also radars. Sometimes  ground-mapping radars of moderately high resolution are used for aircraft navigation  purposes. 
 H. Richter: An Analytical Study of Tropospheric Structure as  Seen by High-Resolution Radar, J. Atm. 
 ING COEFFICIENT VERSUS ANGLE FOR A KNOWN HOMOGENEOUS AREA ARE SCARCE 4HE WORK AT THE -)4 2ADIATION ,ABORATORY  WAS EARLY 7ORK BY 0HILCO #ORPORATION  'OODYEAR  !EROSPACE #ORPORATION  'ENERAL 0RECISION ,ABORATORY  AND THE 53 .AVAL 2ESEARCH  ,ABORATORY .2, n PROGRAMS WERE IMPORTANT EARLY ON 4HE #ANADA #ENTRE FOR  2EMOTE 3ENSING ##23  HAS MADE NUMEROUS AIRBORNE AND GROUND 
 222–234, April 1975. 51. L. 
 It can be seen that the focus of point target C2 at the azimuth center is better, but point targets C1 and C3 at the azimuth edges are noticeably defocused. The main reason is that the estimated Doppler parameters by the basic MAM method are the averaged results of the real ones, and their spatial variance is not considered, resulting in the fact that the point targets at the azimuth edges still have signiﬁcant secondary phase errors. Figures 9c and 10c show the results of the IMAM method. 
 §  Note that the first differences between all combinations of the integers 11, 16, 13, and 17 are 1,2,3,4,5,6. This “perfect  difference set” for the stagger sequence is the key to the relative flatness of the response curves.FIGURE 2.39  Velocity response curve: dual canceler, no feedback, 25:30:27:31  pulse-interval ratio ch02.indd   41 12/20/07   1:44:43 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Clutter levels will be large rel- . ative to most targets and therefore are important in radar design. For the RCS of earth clutter, the surface scattering coefficient a° is multiplied by the resolution cell size A and the cosine of the grazing angle. 
 The  iso-Doppler contours clusters are dependent on the height h (h=1.5 R in Figure 9.4).  The . Radar System Engineering  Chapter 9 – Synthetic Aperture Radar  79     smallest change of the relative velocity and therefore the Doppler frequency results for objects  ahead. 
 ).× × = −−10 526dB  The result is that this array has a mean floor of random sidelobes that on the average  is 52 dB below the peak of the beam. It also illustrates that to achieve low sidelobes  ch13.indd   30 12/17/07   2:40:12 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Diamond, Chapter 3 in Mutual Coupling in Array Antennas , J. L. Allen and B. 
 Here, full sensitivity must be maintained in  the presence of the clutter to maximize the probability of detecting the tar get. The dynamic-range requirement of a pulse doppler radar, as determined by main- beam clutter, is a function not only of the basic radar parameters such as power, antenna  gain, etc., but of radar altitude above the terrain and the radar cross section (RCS) of  low-flying targets. As an example, Figure 4.15 shows the maximum clutter-to-noise  ratio ( C/Nmax) that appears in the ambiguous-range interval, i.e., after range folding, for  a medium-PRF radar as a function of radar altitude and the range of the intersection of  the peak of the main-beam with the ground. 
 The DEM of the scene is ﬁrst generated by processing ArcSAR interferometric images, and then projected on ground range. Finally, this interferometric DEM is used for enhancing the ArcSAR imaging of the targets on the scene. The authors described the procedure, provided an accuracy analysis and presented results obtained by simulating ArcSAR images according to existing radar amplitude data and an external DEM. 
 wavelength apart which are usually supported by low-loss dielectric material. The construc-  tion of the parabolic reflector with thin parallel wires makes it polarization sensitive. That is, it  will completely reflect one sense of linear polarization and be transparent to the orthogonal  sense of polarization. 
 12.1 hasbeen arranged toillustrate asimple A-scope or,alternatively, asimple B-scope. The former requires noequipment beyond that already described. The connections tothe cathode-ray tube areshown asposition Aofthe switch. 
 POL.)  50MHz (HOR. POL )  10 20 30 40 50 60 70 80 90  GRAZING ANGLE (deqrees)  Figure 13.3 Composite of no data for average conditiorls with wind speeds ranging from 10 to 20 knots  the wave scattered from the sea surface are out of phase and produce destructive interference.  (The interference region is not well defined at the highefmicrowave frequencies plotted in  1'1g 17.3.) The angular region between the interference region and the quasi-specular region  ic the plnr~c~tr, or tiiflitse, regiot~. 
 Each scene of the radar data covers a rectangle area of the Earth. The TEC of each scene is estimated as the average TEC of the whole scene. For a quantitative evaluation of the reliability of TEC derived from PolSAR, we compared it to the TEC derived from ISR, because ISR is believed to be the most powerful device for monitoring the ionosphere. 
 For a given tracking error, the error voltage would change  with echo amplitude and target range causing a corresponding change in loop gain. AGC is used to remove the angle-error-detector-output dependence on echo ampli - tude and retain constant tracking loop gain. A typical AGC technique is illustrated in  Figure 9.9 for a one-angle coordinate tracking system. 
 SENSITIVE THAN DIODES  AND THE PHASE WILL CHANGE WITH A CHANGE IN TEMPERATURE 4HIS CAN BE CONTROLLED BY KEEPING THE TEMPERATURE  CONSTANT WITHIN A FEW  DEGREES  ACROSS THE ARRAY ! MORE COMMON TECHNIQUE IS TO SENSE  THE TEMPERATURE AT SEV 
 However, since both the sense of polarization and  the direction of propagation are reversed, the phase shift for a signal traveling from right to left  is the same as that from left to right. The ferrite rod of the Faraday rotator is rnetallizeci to  form a fully loaded waveguide and is accessible for heat sinking. The magnetic circuit is  completed externally with a temperature-stable ferrite yoke. 
 P., arid I. S. Reed: An Analysis of Signal Detection and Location by Digital Means. 
 DENSITY CORE 4HIS CONFIGURATION EXHIBITS HIGH STRENGTH 
 The intersections of the approx- imating segments fall on a curve described by log Ei(M}GN E0(M) = ET G -i— (3.8)log G where E1(M) represents the input levels corresponding to the intersection of the line segments: E1(M) = ETGl~M (3.9) The independent variable M is the order of the stage that is at incipient satura- tion; M will have integer values between 1 and N. In the case of the dual-gain logarithmic amplifier, all intersections of the line segments fall on a logarithmic curve. A typical logarithmic amplifier may have a dynamic range of 80 dB, derived from nine stages, with an overall bandwidth of 5 MHz or more. 
 2.  77. Oliner, A. 
 TRAL CANCELLATION CAN BE USED TO ACHIEVE THE REQUIRED DIRECT 
 -We shall begin with adiscussion that isfundamentally useful inunderstanding what follows, but has asits immediate object adefinition ofthe scope ofthis chapter more precise than isgiven bythechapter title. The simplest conceivable radar system consists ofasource ofr-f power, anantenna, and ascattering object ortarget. The antenna emits waves with time factor eh~, which, onstriking the target ata distance r,are reflected and returned tothe antenna, where their time factor will bee’(”’-’kr) with k=27r/A. 
 7.29 to  7.33 in polar  coordinatesState propagation  is linear  (no pseudo- accelerations).  Radar detections  of less than three  dimensions  can be easily  accommodated.Requires  frequent  coordinate  transforms. Unscented  Kalman  filter55Polar or  Cartesian/   Earth-centeredCartesian/   Earth-centeredCovariance  inferred by  propagating  multiple statesState propagation  is linear  (no pseudo- accelerations). 
 The port-to-port isolation  is used to determine the power level coupled directly between the mixer ports without   frequency translation. The single tone intermodulation levels specify the levels of   the +nfL + mfR spurious signals, as discussed previously. 6.5 LOCAL OSCILLATORS Functions of the Local Oscillator. 
 (/2):/. 2!$!2   Óä°{x THESE IS THE SPREAD DOPPLER CLUTTER DISCUSSED IN 3ECTION    SOMETIMES REFERRED TO AS  ACTIVE OR MULTIPLICATIVE  NOISE 4HE OCCURRENCE OF THIS TYPE OF CLUTTER IS GREATER AT NIGHT  AND IS MUCH MORE PREVALENT IN THE AURORAL ZONES AND AROUND THE MAGNETIC EQUATOR Óä°£äÊ / 
 G. Huizing and A. Theil, CARPET 2.11 Software  + User Manual , The Hague, The Netherlands:  TNO Defense, Security and Safety, 2004. 
 Oceanic Eng ., vol. OE-4,   pp. 31–32, 1979. 
 Hence, if detection no. 9 was received first, it would be assigned to track no.  2. 
 SPEED  TARGET CAPABILITY  -ACH   %XTREMELY WIDE BANDWIDTHS ACHIEVABLE5SE IS GENERALLY RESTRICTED TO APPLICATIONS WHERE PRIMARY  TARGET RADIAL VELOCITIES   -ACH  -ULTIPLE  TUNED MATCHED FILTERS ARE GENERALLY NOT COMPUTATIONALLY PRACTICAL'ENERALLY FOUND IN LOW DOPPLER SHIFT APPLICATIONS'ENERALLY FOUND IN LOW DOPPLER SHIFT APPLICATIONS  4!",%    #OMPARISONS OF 0ERFORMANCE #HARACTERISTICS FOR ,&-  .,&-  AND 0HASE 
 In many cases the total noise power due to the sidelobes can be greater than  the noise power in the main beam. This is especially true when the main beam views the  rel~tively "cool" sky but the sidelobes view the "hot" earth. A portion of the main beam  might also view the relatively "hot" earth if pointed at or near the horizon. 
 2. Rough experi- ments show that the earwill detect apure tone inthe presence ofhiss when the tone isstronger than the noise ina200-cps bandwidth. If the ear can dothis over the range 200 to3000 cps, then byusing the IAdetailed study oftheaural detection problem canbefound inRRL Report No.411-86, May 5,1944,. 
 With the enlarged datasets coupled with transfer learning, CNNs can avoid the over-ﬁtting issue and achieve excellent classiﬁcation accuracy. Comparison experiments demonstrated the good performance of our method. The remainder of this paper is organized as follows. 
 Antennas Propag. Dig ., December 1969, pp. 116–123. 
 Brit. IRE, vol. 17, pp. 
 Am. Meteorol. Soc. 
 TER MAPS  IT WAS THE WORK AT THE -)4 ,INCOLN ,ABORATORY TO IMPROVE THE PERFORMANCE OF AIRPORT SURVEILLANCE RADARS THAT RESULTED IN ONE OF THE FIRST WORKING EXAMPLES OF WHAT HAS BECOME KNOWN AS THE -OVING 4ARGET $ETECTION -4$  RADAR   4HE THEORY  AND EXPECTED BENEFITS OF THIS APPROACH WERE DESCRIBED IN TWO REPORTS IN   WHICH  PROVIDED THE MATHEMATICAL FOUNDATION FOR THE UNDERSTANDING AND  THE PRACTICAL IMPLE 
 TRACK DIMENSION IS MUCH SMALLER THAN THE AZIMUTH RESOLUTION REQUIRED OF THE DATA 4HE LOOKS PARAMETER  . ,  DESERVES SPECIAL COMMENT IN THE 3"2 CONTEXT  SUMMARIZED BELOW 4HE -AGELLAN ANTENNA WAS USED AS THE HIGH 
 A specified  fractional increase F in frame time accounts for the execution of Confirm dwells to  reject false Alert detections. F is on the order of 5–10%. When using a VS Alert and a  3-look HRWS Confirm, the probability of false alarm per range-doppler cell, PFA,a and  PFA,c for Alert and Confirm, respectively, is  PT N N T PNTad a r a f a a c r cdFA FR FA,, , , , , ,,ln( )= =2 1 2c c fN N TF Fln( ) ,2 1 21 3 cue F M F R×+    (4.19) where Td,a = total Alert dwell time  Nr,a = number of independent range samples processed per IPP in Alert  Nf,a =  number of independent doppler filters visible in the Alert doppler   passband  TFR,a = Td,c /F = Alert false report time  Td,c = total Confirm dwell time  F = fractional increase in frame time allocated to Confirm (5–10%)  Nr,c = number of independent range samples processed per IPP in Confirm  Nf,cue =  number of independent doppler filters in the Confirm window centered  about the doppler of the Alert detection cue  NFM =  number of independent doppler filters in Confirm linear-FM ranging  doppler correlation window  TFR = overall Alert/Confirm false report time The M-of-N ranging used in MRWS requires correlation in range and can be viewed  as a binary detector. 
 Angle ^ 1 deg.* = NoiseJUL SSN = 100 TIME = 18 GMTLOCATION 38.65 N LAT 76.53 W LON BEARING= 90.00 DEG FIG. 24.24 Radar performance estimate; July, 1800 UTC. (a) SSN = 10. 
 TONE PARAMETER ESTIMATION FROM DISCRETE 
 Note that two antennas  are used: one transmits and one receives.  s t s t s t s t s t s t s tr s c t ( ) ( ) ( ) ( ) ( ) ) ( ) = ⊗ ⊗ ⊗ ⊗ ⊗af gf gr⊕ ⊕ +s t n tar( ) ( ) (21.12) where  ss(t)  = signal applied to the antenna  sad(t)  = antenna impulse response  sc(t)  = antenna cross coupling responseFIGURE 21.23  Predicted and actual pulse responses of loaded TEM horn antenna  (Courtesy IEE )20? ? ? ? ? ? ? ? ? 21 25 Time (ins)26 30Ch. 2 = 80.00 mVolts/div  Timebase = 1.00 ns/divOffset = 0.000 Volts Delay = 240.180 ns250.180 ns 240.180 ns 245.180 ns 29 27 28 24 23 22 ch21.indd   30 12/17/07   2:51:43 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 BAND NORMALIZED RADAR CROSS SECTION OF !MAZON RAINFOR 
 LEL COMBINATION OF &%4 CELLS IN THE OUTPUT STAGE 4HIS EXAMPLE WAS FABRI 
 TO 
 DOPPLER CELL THAT HAD A DETECTION IN THE MAIN CHANNEL &OR THESE RANGE 
 180. E. Im et al., “Second-generation precipitation radar (PR-2),” Final Rep. 
 The complete transformation process is shown in Figure 10. =ișș Figure 10. The polar coordinate transformation method proposed in this paper. 
 V-beam: radar, is a satisfactory method for obtaining three­ coordinate target information if the number of targets is not excessive. The larger the number  of targets, the more difficult is the problem of correlating the echoes from each of the two  beams. The closer the beams, the easier..it is to correlate the echoes, but the less the accuracy. 
 62. J. W. 
 With a  sufficiently low VSWR, the magnetron operation will not occur in either the sink or the  antisink region, no matter what the phase angle of the load.  Reference point is ·  waveguide flange Figure 6.7 Rieke, or load, diagram for the  SFD-341 coaxial magnetron. Duty cycle =  0.0009, peak current = 24 A, pulse width =  2.25 µs, frequency = 5.65 G llz. 
 Ultraportable Units.—Where extremely light weight isrequired this can beobtained only bysacrificing reliability orbyshortening the required period ofoperation. Ultraportable ground radar systems usually need very little power. Where only afew hours ofoperation are required, the systems can be powered bysmall storage batteries which operate vibrator power supplies ordynamotors. 
 Cooling the device will therefore  improve the noise figure."  The tunnel-diode amplifier has been considered in the past as a low-notse front-end, with  noise figures from 4 to 7 dB over the range 2 to 25 GHz." It has been supplanted by the  improvements made in the transistor amplifier. The traveling-wave-tube amplifier has also  been considered as a low-noise front-end, but it has been overtaken by other devices. Cryo-  genic parametric amplifiers and masers produce the lowest noise figures, but the added  complexity of operating at low temperatures has tempered their use in radar. 
 The phase information is stored in a PRI (pulse repetition inter- val) memory for the period between transmitted pulses, and it is also subtracted . FIG. 15.1 (a) Normal video, (b) MTI video. 
 Hauser, G. Caudal, and B. Chapron, “A semiempirical model of the normal - ized radar cross-section of the sea surface 2. 
 Mumford, W. W., and E. Scheibe: "Noise: Performance Factors in Communication Systems," Horl-  zon House-Microwave, Inc., Dedharn, Mass. 
 II Plans to develop a properly engineered version of ASV Mk. I had started in January1940 and many lessons were learned from the shortcomings of ASV Mk. I. 
 However, because fine range resolution is  so necessary to a successful SAR, and also because of an analogy between range and  crossrange resolution, we discuss range resolution briefly here. Fine range resolution is achieved by transmitting and receiving radar waves char - acterized by a fairly wide bandwidth B. As an example, consider a carrier frequency   f = 10 GHz and a 10% bandwidth B = 1 GHz. 
 SCATTERING AND AN ATTENUAT 
 Burkett: Radar Sea Return-JOSS I, Naval Research  Laboratory Report 7268. Washington, D.C., May 11, 1971.  4. 
    PP n    & 4 5LABY  ! !SLAM  AND - # $OBSON  h%FFECTS OF VEGETATION COVER ON THE RADAR SENSITIVITY TO  SOIL MOISTURE v 5NIVERSITY OF +ANSAS  2EMOTE 3ENSING ,AB  42  
 These targets now have to compete  only with system noise. This noise can be both additive and multiplicative. Additive  noise tends to mask multiplicative noise in low-performance radars. 
 For a typical duplexer it might be or the order of 1 dB. A  .::: 1.0  0  0  '-.  QJ  -0 . 
 Accuracy of frequency (doppler-velocity) measurement. Using the method of inverse probabil-  , ity, Manassee showed that the minimum rms error in the measurement of frequency is  where  and s(t) is the input signal as a function of time. Note the similarity between the definition of a  and /I, as defined in Eq. 
 Intheliterature onSAR,theradarequation isusuallywrittenwiththe signal-to-noise ratio(SIN)ontheleft-hand side.We'startwiththefollowing P A2al!SIN=----'-"--- (14.14)4rrA2kToBFnR4. where P, = peak transmitted power  A, = effective aperture of the real antenna  a = target cross section  tt = number of pulses integrated (cot~erently)  A = wavelength  kTo = 4 x lo-*' W/Hz  B = receiver bandwidth  F, = receiver noise figure  R = range  This equation is modified by substituting P, = P,,/T~;, wlw-e P,, = average power, T = pulse  width = 1/B, and f, = pulse repetition frequency. Also 11 =/ito, where to = L,/v = time  required to generate the synthetic aperture whose length is given by L, = RAID, v = velocity of  the vehicle carrying the radar, and D = real-antenna dimension. 
 -/"  &IGURE A SHOWS A TYPICAL ANTENNA MAIN 
  D" 0ROVIDES LOW 0&! DUE TO DISCRETES )NDEPENDENT $ISCRETE 2EQUIREMENT   D"C #OMMON $ISCRETE 2EQUIREMENT   D"C  D" LESS THAN )NDEPENDENT $ISCRETE.   05,3% $/00,%2 2!$!2   {°Î£ 4O REDUCE DOPPLER FILTER SIDELOBES  A  D" $OLPH 
 This procedure is known as motion compensation  (sometimes abbreviated  mocomp ). For example, at a particular moment, as a particular frequency is transmit - ted, if the antenna is estimated to have deviated a distance d away from the nominal  flight path along the LOS, the phase correction  ∆φπ λπ= =4 4d d f c (17.10) with appropriate sign, is added to the measured phase at the frequency f to produce  the best estimate of what the recorded phase would have been if the platform had not  deviated from the nominal flight path. Similarly, if the platform speed is not constant,  the received data are interpolated to produce the best estimate of what they would have  been if the speed had been constant. 
 Temme, “A solid state ‘flux drive’ control circuit for latching- ferrite-phase shifter applications,” Microwave J ., vol. 15, pp. 59–64, September 1972. 
 The  acronym RADAM, which stands for radar detection of agitated metals, has sometimes been  used to describe this effect.69  Inverse scattering. In principle, the size and shape of a target can be found by measuring the  backscattered field, or radar cross section, at all frequencies and all aspects. It is not possible,  of course, to obtain sucll complete information, but the process can be approximated by  measuring the backscatter at a finite number of frequencies and aspects. 
 278-287, July-October, 1965.  43. Marcum, J.: A Statistical Theory of Target Detection by Pulsed Radar, Mathematical Appendilt, I RE  Trans., vol. 
 Sachs: Wind Effects on Microwave Reflectors, "Design and Construction  of Large Steerable Aerials," IEEE (London) Con( P11hlicatio11 no. 21, pp. 29-38, 1966. 
 BEAM CLUTTER  ALTITUDE 
 RANGE INSTRUMENTATION RADAR 4HE PRINCIPAL APPLICATIONS OF PRECISION TRACKING RADAR ARE WEAPON CONTROL AND   MISSILE 
 The linear relation between delay time and range shown inEq. (I)is. 4 INTRODUC7”ION flik~c ‘<2”’”Target[SEC. 
 CODED DOMAIN RADAR DESIGNS ARE MOST LIKELY TO BE ENCOUNTERED &REQUENCY DOMAIN RADARS MAY USE EITHER STEPPED FREQUENCY OR CONTINUOUSLY SWEPT FREQUENCY MODULATION 4HEY TRANSMIT  ON A REPETITIVE BASIS  A NOMINALLY CONSTANT AMPLITUDE SIGNAL WHOSE FREQUENCY INCREASES IN A LINEAR PROGRESSION FROM THE LOWEST TO THE HIGHEST VALUE 2ECOVERY OF THE RECEIVER SIGNAL FROM NOISE MAY BE ACHIEVED BY EITHER CONVENTIONAL  BANDPASS FILTERS OR BY THE MATCHED FILTER OR 7IENER FILTER 4HE FUNDAMENTAL OPERATION OF A MATCHED FILTER IS CORRELATION 4HE AMPLITUDE OF  EACH POINT IN THE OUTPUT SIGNAL IS A MEASURE OF HOW WELL THE FILTER KERNEL MATCHES THE CORRESPONDING SECTION OF THE INPUT SIGNAL 4HE OUTPUT OF A MATCHED FILTER DOES NOT NEC 
 MAPPING RADAR  THERE HAS BEEN CONTINUOUS DESIRE TO ACHIEVE FINER RESOLUTION 7E SHALL USE THE TERM  RANGE RESOLUTION TO MEAN THE RESOLU 
 The probability that the envelope of the noise voltage will lie between the values of V, and  V2 is  v2 R Probability (V, < R < V2) = - exp (- 5) dR  v, +o 2+0  The probability that the noise voltage envelope will exceed the voltage threshold V,- is  "R Probability (VT < R < m) = [ - exp (- c) dR  v7. $0 2$ 0  = exp (- 2) = P,,  Whenever the voltage envelope exceeds the threshold, a target detection is considered to have -?  occurred, by definition. Since the probability of a false alarm is the probability that noise will  cross the threshold, Eq. 
 M. Johanson. C. 
 through the measurement cell. The wind speed was 16.5 m/s, and a doppler shift of 100 Hz corresponds to a radial velocity of 1.6 m/s. The average clutter spectrum ex- pected for this wind speed and grazing angle, with bandwidth obtained from Eq. 
 However, radar rays arerefractedslightlymorethanlightraysbecauseofthefrequenciesused.Iftheradar waves actually traveled in straight lines or rays, the distance to thehorizon grazed by these rays would be dependent only on the height of theantenna, assuming adequate power for the rays to reach this horizon.Without the effects of refraction, the distance to the RADAR HORIZONwould be the same as that of the geometrical horizon for the antenna height.Standard Atmospheric Conditions The distance to the radar horizon, ignoring refraction can be expressed in the following formula. Where h is the height of the antenna in feet, thedistance, d, to the radar horizon in nautical miles, assuming standardatmospheric conditions, may be found as follows: With the distances to the geometrical or ordinary horizon being 1.06 and the distance to the visible or optical horizon being 1.15 . We see thatthe range of the radar horizon is greater than that of the optical horizon,which again is greater than that of the geometrical horizon. 
 Circuit for S~~erlieterodyl~c Kcceivers. C).S'l'. vc)l. 
 drift of the magnetron without having to retune too often. In July 1945 ASWDU reported on a trial of a narrow bandwidth receiver for ASV Mk. VI [ 22]. 
 237-2S2.  March, 1973.  147. 
 The main beam illuminates the elliptical area to the left of the ground track. Since  this area lies entirely within the filter area, the main-beam clutter falls within this filter,  and all other filters receive sidelobe clutter. Four range annuli are intersected by the  main-beam ellipse, so the main-beam clutter in this range gate is the vector sum of  the signals received from all four clutter patches. 
 191–200.  9. E. 
 Spacecraft velocities at these LEO altitudes are on the order of 7.5 km/s; their cor - responding periods are about 100 minutes. Earth rotation (at a rate of ∼0.25 degree/ min) shifts the sub-satellite point at the equator by ∼3300 km orbit-to-orbit. The orbit  altitude normally may be chosen to tune the period and Earth rotation rate so that an  exact-repeat pattern develops that has a stipulated number of days. 
 VERT THIS HIGH 
 RATE 3CAN3!2 DATA TAKES DUR 
 If the material properties are dominated by electric effects, the optimum  layer thickness is close to l/4, as measured in the material. If they are dominantly  magnetic, the layer can be much thinner. As with the simple Salisbury screen, Dällenbach layers can be cascaded in attempts  to expand bandwidth, producing what is known as graded absorbers . 
 TIONS  THE LOSS IS REFERRED TO AS A PROPAGATION LOSS RATHER THAN A PATH LOSS 4HE PROPAGA 
 . RANGING TO ACHIEVE THE NECESSARY RANGE  ACCURACY FOR SINGLE 02& TRACK UPDATES 4HE UNAMBIGUOUS (273 RANGE MEASUREMENT OF THE SEARCH DETECTION IS USED TO HELP RESOLVE THE RANGE AMBIGUITY &OR -273 DETECTIONS  ANOTHER -273 DWELL IS USED FOR 4RACK !CQUISITION /NCE THE TRACK FILE IS INITIATED  SEVERAL RAPID TRACK UPDATES ARE USED TO FIRMLY ESTABLISH THE TRACK 7HEN DOING 3INGLE 
 In some of the  smaller rigid radornes, snow can be removed mechanically by tying a rope at the top and  having someone walk the rope around the radome to knock off the snow.  Liquid water can collect on a radome due to condensation or rainfall. In some cases, the  impirigement of rain on a radome can have a more serious effect on the system performance  than the rainfall along tlie propagation path. 
 74,7SWith20 independent samples thelossis1.5dB,andwith40samples itis0.7dB.Theaboveappliesto single-hit detection. Thelossdecreases withincreasing numberofpulsesintegrated. With10 pulsesintegrated, thelosswith10independent samplesdecreases to0.7dB,andto0.3dBfor 100pulsesintegrated.B8 Ifthetargetechoislarge,energycanspilloverintotheadjacent range-resolution cellsand affectthemeasurement oftheaveragebackground. 
 1333–1341,  1968. 61. Y . 
 ACCELERATIONS AND ACCOMMODATES MEASUREMENTS OF ANY DIMEN 
 The phase errors introduced  can then be corrected by programming the phase shifters. This will have the beneficial  effect of breaking up the quantization errors and thereby reducing quantization lobes. Feed Effect. 
 If the receiving antenna uses a broad fixed beam, the problem of pulse chasing is  alleviated. However. the smaller effective antenna aperture associated with the broad receiving  beam results in less eclio signal. 
 ARRAYS ARE CONFIGURED REASONABLY  THE NUMBER OF SUB 
           P(Z   WHICH  IS A STABILITY OF  PART IN  FOR THE STALO AT ABOUT  '(Z  AND  PART IN  FOR  THE COHO ASSUMING A  
 Equation 8.13appliesforauniform aperture- illumination. Withacosine-on-a-pedcstal aperture illumination oftheformAn=ao+2alcos2rrnlN,thebeamwidth is111 0.886A[ ( )2]0B::::::--------1+0.636laIlaoNt!cos00(8.14) Theparameter nintheaperture illumination represents the position oftheelement. Sincethe illumination isassumed symmetrical aboutthecenterelement, theparameter IItakesonvalues ofII=O.±1,±2,...,±(N-1)/2.Therangeofinterestis0::;2aI::;aowhichcoversthespan fromuniformilluminations toatapersoseverethattheillumination dropstozeroattheends ofthearray.(Thearrayisassumed toextendadistanced/2beyondeachendelement.) Theaboveappliestoalineararray.Similarresultsapplytoaplanaraperture; 17,111thatis, thebeamwidth intheplaneofthescanvariesapproximately inversely ascos00,provided certainassumptions arefulfilled. 
 40 COS $  Equatiori 14.1 1h would also be modified accordingly. The condition given by Eq. (14.13), and  similar relations, represent an upper bound on tlie capabilities of an SAR to achieve a resolu-  tion 6,, over a swath S,.. 
 NOISE  ARE THEN RE 
 ANGLE MICRO 
 Atable clamped totheyoke supports thegyro-torque unit and aservoamplifier. The gyro ismounted ingimbals and isprovided with one synchro take-off FIG.935,-A stabilizing attachment mountwl onanairborne scanner. Thereflector has been replaced byacamera fortestpurposes. 
 (b) Imperfect motion compensation due to displacement error and alignment error a. FIG. 16.10 Switching network to synthesize displaced subarrays, within an antenna ar- ray. 
 Two further limitations on / are the effect of pulse-to-pulse repetition-period staggering combined with clutter spectral spread from scanning and internal- clutter motion. These limitations, plotted in Figs. 15.16 and 15.17, apply to all cancelers, whether single or multiple. 
 Thus, there tends to be a small number of  manufacturers who provide quality devices for use in amplifier designs. Silicon-based microwave power transistors can actually be considered hybrid  microelectronic circuits and are generally single-chip or multichip transistors com - bined in parallel within a flanged hermetic package. Some form of internal impedance  prematching circuitry is often included in order to preserve the intrinsic bandwidth of  the semiconductor chip and to make the task of external impedance matching easier. 
 DAY REPEAT OF THE 4/0%80OSEIDON RADAR ALTIMETER /RBIT PARAMETERS SUCH AS REPEAT PERIOD MUST BE MAINTAINED  REQUIRING SMALL BOOSTS FROM SPACECRAFT THRUSTER MANEUVERS   TYPICALLY APPLIED EVERY  SEVERAL WEEKS FOR ,%/ MISSIONS 4HE REVISIT TIME OF A GIVEN 3"2 ASSET DEPENDS ON THE RANGE SWATH WIDTH COVERED BY THE RADAR IN QUESTION  AS WELL AS THE ORBITS EXACT 
 CONTROLLED EXPERIMENTS NEAR GRAZING ARE ALSO SCARCE EXCEPT FOR  A MAJOR ,INCOLN ,ABORATORY PROGRAM !IRBORNE MEASUREMENTS ARE NECESSARY TO MAKE LARGER SCATTERING AREAS ACCESSIBLE  !LTHOUGH AIRBORNE PROGRAMS FOR SPECIAL PURPOSES HAVE BEEN LEGION  CURVES OF SCATTER 
 (17.12) and (17.13) are: f\ 18 18 18 23/O 21 21 29 29/2 24 35 35 352/o 42 42 58 58/1 + /2 42 53 53 58Target? Yes No No YesRange, nmi 10 20Target Range, nmi Doppler frequency, kHz FM shift, kHzA 10 21 3 Observed frequencies /n, no FM, kHz /,, FM up, kHz /2, FM down, kHz21 18 24B 20 29 6 29 23 35 . ther continuously or in a pause-to-range mode (discussed in Sec. 17.5). 
 Time sidelobes of compressed pulses in radars that transmit coded waveforms can  be degraded by STC. Gradual changes can usually be tolerated, but at close range, the  rate of change of attenuation can be very large. Most modern radars that include STC  use digital STC control, which can lead to large step sizes at close range unless high  digitization rates are used. 
 215–236. 12. J. 
 175, pp. 681–683, 1955.  6. 
 †  Low values of carrier frequency and time-bandwidth product have been used to illustrate the variation of instanta - neous frequency over the pulse in Figure 8.2. ch08.indd   4 12/20/07   12:49:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 § ©¨¶ ¸·OBS         4HE DOMINANT DESIGN PARAMETERS IN THE EQUATION ARE THE ACCURACY OF THE RADAR AND  THE OBSERVATION TIME "ETTER ACCURACY OR LONGER OBSERVATION TIME ALLOWS MORE ACCURATE  MEASUREMENT OF VELOCITY  -AKING MORE DETECTIONS IN THE OBSERVATION TIME IMPROVES THE ACCURACY BUT ONLY IN A SQUARE 
 The data was plotted as a ratio of bistatic to monostatic  RCS, sB/sM. The measurements generally match Kell’s model: of the 27 data points,  24 show bistatic RCS lower than monostatic RCS. The reduction in bistatic RCS starts  between b = 5° and b = 10° and trends downward to sB/sM = −15 dB at b = 50°. 
 2015 ,36, 4621–4631. [CrossRef ] 8. Karimova, S. 
 C., and J. W. R. 
 16.8 SPACE-TIME ADAPTIVE MOTION COMPENSATION Several methods have been described to compensate for antenna motion. All these techniques are applied in the radar design phase for a specific set of oper- ational parameters. Controls (usually automatic) are provided to adjust weights for operational conditions around the design value. 
 The  observed quantities are usually the output power, the wavelength, and the anode voltage.  The problem of presenting the variation of the three quantities-power, wavelength, voltage­ as a function of the four parameters mentioned above is greatly simplified since the input and  output parameters operate nearly independently of each other. Thus it is possible to study the  effect of the magnetic field and the anode current at some value of load susceptance and  conductance chosen for convenience. 
 Rannou, and M. Lesturgie,  “A general presentation about the OTH-Radar NOSTRADAMUS,” IEEE Radar Conference ,  Syracuse, NY, May 2006. Also reprinted in IEEE AES Systems Magazine , vol. 
 RANGE DIMENSION IS AGAIN EQUAL TO THAT OF CLUTTER OR THERMAL NOISE 3POT JAMMER NOISE WILL APPEAR TO BE STRETCHED IN RANGE u 2ANDOM PULSE JAMMING 4HE JAMMER PULSES MAY ALSO BE TRANSMITTED AT RANDOM INTER 
 Thefour-thirds earthapproximation hasseverallimitations. Itisonlyanaveragevalue andshouldnotbeusedforotherthangeneralcomputational purposes. Thecorrectvalueofk depends uponmeteorological conditions. 
 dissertation,  University of Lulea, Sweden, 1978. 11. D. 
 between direct and reflected rays can occur. This subject. istreated indetail inl“ol. 
 Crain, A. M. Shapiro, J. 
 Based on the stop-go assumption, the SAR signal penetrates the ionospheric phase screen twice at one sampling point with different instant frequency (the SAR transmit signal is linear modulated). Thus, the random phase induced by ionospheric irregularities can be properly analyzed by the two-position two-frequency function. Based on the phase screen theory, Li et al. 
 Theratioaisdefined asanumber lessthanunity.Theangular error ~IJas measured fromthelargerofthetwotargetsis3! 110a2+acosCi. 8D=1+a2+2acosCi. ThisisplottedinFig.5.13.Theposition ofthelargerofthetwoscatterers corresponds to !!.(J/OIJ=0,whilethesmaller-scatterer position isat110/0D=+1.Positive valuesof!!.(Jcorre­ spondtoanapparent radarcenterwhichliesbetween thetwoscatterers; negative valueslie outsidethetarget.Whentheechpsignalsfrombothscatterers areinphase (Ci.=0),theerror reducestoa/(a+1),whichcorresponds totheso-called" centerofgravity" ofthetwoscat­ terers(nottobeconfused withthemechanical centerofgravity). 
 73. Ashley, J. R., T. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.736x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 The rms pulse-to-pulse transmitter phase-shift change (if a power amplifier) must  be less than  ∆φ= = =1 316000316 0 180. 
 Although it may be well suited  for comniercial TV, it is not always a good display for radar since its resolution is limited  by the size and spacing of the dots. Another color CRT of interest to radar is the penetration  color rtrhe using a multi-layer screen. The color is controlled by the anode voltage which  determines the depth of penetration of the electron beam into a series of phosphor layers. 
 (Courtesy of Lockheed  Martin Corporation ) AN/SPY-1 .113,114 This S-band phased array radar is part of the Navy Aegis weapon  system and was developed by RCA, now Lockheed Martin. It has four phased array  apertures to give unobstructed hemispherical coverage (Figure 13.1). In its early con - figuration, it used a simple feed system with, on receive, 68 subarrays, each contain - ing 64 waveguide-type radiators for a total of 4352 elements. 
 This can represent an expensive trade. If instead of one receiver  per bean). only one or a few receivers are time-shared over the total coverage, some form of  stvitcliing is required. 
 #HEBYSHEV WEIGHTING IS APPLIED   WHICH REDUCES THE COHERENT INTEGRATION 3.2 GAIN BY ABOUT  D" &OR DETECTION  THREE #0)S ARE INTEGRATED NONCOHERENTLY VIA 0$) FOR AN APPROXIMATE INTEGRATION GAIN    IN D" OF  LOG .0$)   OR  D" 4HIS RESULTS IN A THERMAL 
 L. Poirier, “An analysis of simplified feed architectures for MMIC T/R module arrays,” Rome  Air Development Center Rept.  RADC-TR -86-236 (AD A185474), February 1987. 
 02& RADAR WHERE THE CLUTTER IS AMBIGUOUS IN BOTH RANGE  AND DOPPLER 4HE RADAR PLATFORM IS MOVING TO THE RIGHT AT  KT WITH A DIVE ANGLE  OF  4HE NARROW ANNULI ISO 
 4.3 ASV Mk. VIA, ARI 5571 As discussed above, the ASV Mk. VIA [ 8] mainly differed from ASV Mk. 
 COOLING 
 b. Turn brightness control until a full diameter trace is just visible, then turn it about 3 clicks anti-clockwise. c. 
 Angle fluctuations are due to random changes in the relative distance from radar to the  scatterers, that is, varying values of a. These changes may result from turbulenct in the aircraft . TRACKING RADAR 169  0.5  0.4 ·  0.2  0 a == 0  t::.B  Bo· --0.2 - ·-04  --0.6  '- -0.8 - -1.0  0 ?O <'10 60 80 100 120 140 160 180  Phase difference Cl'.'  Figure 5. 
 K. Moore, K. A. 
 " .   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°Óx OTHER RADAR SENSORS WINGMAN OR SUPPORT AIRCRAFT  ON SIMILAR PLATFORMS TO REPORTS BY  OBSERVERS WITH BINOCULARS "ECAUSE THE MODERN FIGHTER IS NET 
 46. M. Katzin, “On the mechanisms of radar sea clutter,” Proc. 
 POINTING DIRECTIONS CAN BE ACHIEVED 4HE GENERAL PLANAR ARRAY CHARACTERISTICS ARE READILY OBTAINED FROM A FEW SIMPLE  EQUATIONS THAT ARE GIVEN HERE BUT DISCUSSED LATER IN GREATER DETAIL 7ITH THE ELEMENTS SPACED BY  K  K   WAVELENGTH  TO AVOID THE GENERATION OF MULTIPLE BEAMS GRATING  LOBES   THE NUMBER OF RADIATING ELEMENTS  . FOR A PENCIL BEAM IS APPROXIMATELY RELATED  TO THE BEAMWIDTH BY   . "y    P    P".y  WHERE P" IS THE  
 But, in general, it is the method by  which angle tracking is accomplished that distinguishes what is normally considered a tracking  radar from any other radar. It is also necessary to distinguish between a conti1111011s crnd.:i11y  radar and a track-while-scan (TWS) radar. The former supplies continuous tracking data on a  particular target, while the track-while-scan supplies sampled data on one or more targets. 
 17.7  17.2 Pulse Doppler Clutter  .............................................  17.9  General  .............................................................  17.9 Ground Clutter in a Stat ionary Radar  ................. 
 From the radar system standpoint, these are all filter - ing functions, and in modern radar systems, these functions are performed using  digital signal processing on the receiver output I and Q data. These functions are  discussed in other chapters of this handbook. The purpose of the filtering within  the receiver is to reject out-of-band interference and digitize the received signal  with the minimum of error so that optimum filtering can be performed using digital  signal processing. 
 Peacock, Statistical Distributions,  3rd Ed. New York, John Wiley  & Sons, Inc., 2000, p. 13. 
  AND !)3 
 Main Step Operation Complexity SI: Achieving three sub-view images FFT 15 Nalog2Na SII: Estimating ˆedr(fdc)and ˆe3rd(fdc) (Loperations of sliding windowing manipulation, window width: Nw)STFT 30 LN wlog2Nw Complex conjugate multiplication 21 LN w IFFT 15 LN alog2Na Modulus 27 LN a SIII: Estimating the ﬁtting coefﬁcients ofˆedr(fdc)and ˆe3rd(fdc)Curve ﬁtting 32 L Scom: Total 15 Nalog2Na+(30Nwlog2Nw+21Nw+15Nalog2Na+27Na+32)L Therefore, the computational complexity of the main steps for the EMAM method can be written as (18). Scom=SI+SII+SIII. (18) In order to improve the accuracy of the Doppler parameters, multiple iterations are performed. 
 766–779. 88. F. 
 16.21. The effectiveness of the correction varies with elevation angle since the actual displacement along the line of sight varies with elevation angle. This effect is more pronounced at higher aircraft speeds and higher radar frequencies. 
 TheswitchshowninFig.6.14isahydrogen thyratron, butitcanalsobeamercury ignitron, sparkgap,silicon-controlled rectifier(SCR),orasaturable reactor.Agastubesuch Fieure6.13Basicelements ofonetype ofradarpulsemodulator. Discharge path Charging pathChargingEnergy -impedancestorage t-- element f------- ------1 Energy- (-----iI-load soun:e-I Switch,trtr-- I L~__JI'--T-----__..J j \.. Energy  sourse Chorglng Chorq~nq  rmpedance dode  1 , Pulse  transformer  Damping  network  Figure 6.14 Diagram of a line-type modrrlator. 
 Since target illumination occurs only in short bursts, the use of a sweeping gate for acquisition would result in excessively long acquisition times. The doppler uncertainty region must, therefore, be examined simultaneously by a bank of contiguous doppler filters. The illumination burst must be shaped or the received signal time-gated to prevent the spreading of clutter through the target doppler spectrum owing to the pulsed nature of the transmission. 
 ING THE TARGETS DOPPLER WITH THE DIRECT PATH SIGNAL IN THE RECEIVER 7ILLIS PROVIDES AN  EXPRESSION FOR F" WHEN ALL THREE SITES ARE IN MOTION %QUATION  SHOWS THAT L 7HEN A   n  F" REDUCES TO THE MONOSTATIC CASE FOR A MONOSTATIC RADAR LOCATED ON THE  BISTATIC BISECTOR 4HE MAGNITUDE OF THE BISTATIC DOPPLER IS NEVER GREATER THAN THAT OF  THIS MONOSTATIC DOPPLER L 7HEN A   n  F"    FOR ANY C  WHICH IS THE FORWARD 
 13,  pp. 539-543, McGraw-Hill Book Company, New York, 1951.  16. 
 If radar beacons aretobeprovided, awhole new setofthem isrequired for every new band offrequencies used. British opinion hasinclined tothe view that the resulting multiplicity ofbeacons isintolerable, that it involves fartoogreat acost forthedesign, manufacture, installation, and maintenance ofthese many differrnt beacons. The British policy has been todesign forevery radar setasupplementary synchronous beacon interrogator for interrogating beacons inthe 200-Mc/sec region and receiving replies atsuch afrequency, thereplies tobedisplayed whenever possible onthe indicator ofthe radar set. 
 DELAY SCANNING !NOTHER POSSIBLE CONFIGURATION PROVIDING MULTIPLE BROADBAND BEAMS USES PARALLEL PLATES CONTAINING A WIDE 
 L. Ci. Dennett, and L. 
 To accommo­ date an increase in pulse width to 102.4 microseconds  with unchanged signal bandwidth (time-bandwidth prod­ uct of 32,768), a digital chirp generator developed previ­ ously with NASA support was incorporated (Fig. 5). A  linear ramp is accumulated to provide a number repre­ sentative of the signal phase that varies parabolically with  time. 
 TRACKING RADAR  9.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 This chapter describes the monopulse (simultaneous lobing with either phase com - parison or amplitude comparison), conical-scan, and sequential lobing tracking-radar  techniques with the main emphasis on the amplitude-comparison monopulse (simul - taneous lobing) radar. 9.2 MONOPULSE (SIMULTANEOUS LOBING) The susceptibility of conical scanning and sequential lobing tracking techniques to  echo amplitude fluctuations and amplitude jamming (as described in Section 9.3)  was the major reason for the development of tracking radar that provides simultane - ously all the necessary lobes for angle-error sensing. This required that the output  from the lobes be compared simultaneously on a single pulse, eliminating the effects  of echo amplitude change with time. 
 When  testing an up - converter from the IF system, or testing the power amplifier, a  radar pulse generator is needed in addition to  the pulse  analyzer.   There are several solutions available for generating radar  pulses. Arbitrary Function Generators  (AFGs) , Arbit rary  Waveform Generators  (AWGs) , and software to create the  necessary pulses can generate baseband, IF, RF, or  microwave signals usin g direct synthesis up to 10 GHz and  higher . 
 As they rise, they grow in size and can reach a diameter of 1 to 3 km. They  rise until they lose buoyancy or until they reach a level where condensation takes place. The  tops of the cells might be at altitudes from I lo 2 km. 
 38. Lain, C. M., and E. 
 The technical vision of the 1946 meeting was remarkable. For instance, it was seen  that in the future it would be possible to overlay radar data automatically onto a chart  image displayed on a “television” type screen. This was not to be realized on com - mercial systems for 50 years. 
 THE 
 The beats inthetelephones now consist ofasuccession ofpulses whose envelope has the doppler frequency f~.Note that the doppler effect can beviewed ascausing aphase shift ofthe echo from pulse to pulse. Itiseasy tocalculate this phase change and toshow that itis equivalent tothe frequency shift. The distance traveled bythe target between pulses isuT,where Tisthe repetition period. 
 Sampled systems are subject to the Nyquist limit,1 which lower bounds the sampling  rate at which reconstruction of the unsampled signal from its samples is possible with - out corruption by aliasing , the overlapping of spectral components. The bound, termed  the Nyquist frequency  or Nyquist rate,  is equal to the two-sided signal bandwidth B,  the bandwidth considering components at both positive and negative frequencies.  Sampling below the Nyquist rate always results in aliasing, but sampling above it does  not guarantee alias-free operation. 
 1957. 46.Condie, M.A.:BasicDesign Considerations: Automatic Navigator AN/APN-67, IRETrans.• vol.ANE-4. pp.197-201. 
 2. Increased reliability: Batch-processed components lead to a reduced num- ber of parts, from the reliability standpoint, and hence to increased reliability. 3. 
 IfSisthesignal power received, Pthetransmitted power, Gthegain oftheantenna, Athe wavelength, athe radar cross section ofthe target, and Rthe distance tothetarget orrange, this relation must hold: ‘‘(s)(&)(z) (3a) The quantity inthefirst parenthesis isthepower density intheincident wave atthetarget. The first two terms inparentheses together give the power density inthe returning wave atthe radar antenna, and the last factor will berecognized asthe receiving cross section ofthe radar antenna, from Eq. (2). 
 The sheet resistivities must increase from a low value at  the inner sheet to a high value at the outer sheet. ch14.indd   37 12/17/07   2:47:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
         . Ó{°Ón  2!$!2 (!.$"//+  OF SUB 
 The target aspect angle is zero for a head-on condition and 180° for a tail chase. The aspect angle corresponding to the boundary between the sidelobe clutter region and the sidelobe clear region is a function of the relative radar-target velocity ra- tio and is shown in Fig. 17.4 for four cases. 
 Int. Telemetry Conf . vol. 
 if11.f=O.lfo,thefirstblindspeedcorresponding tothe difference frequency is10timesthatofanMTIradaratthecarrierfrequency 10.Thus,itwould seemthattheadvantages ofaVHForUHFMTImightbeobtained withradarsoperating at thehighermicrowave frequencies. Atwo-frequency MTItransmits apairofpulses,either simultaneously orinclosesequence. attwoseparate carrierfrequencies. 
 +OSMOCA  2ADAR /BSERVATION OF THE %ARTH FROM 3PACE    ,ENINGRAD (YDROMETEOIZDAT    )N 2USSIAN   -ITNIK ET AL  h3TRUCTURE AND DYNAMICS OF THE 3EA OF /KHOTSK MARGINAL ICE ZONE FROM @OCEAN  SATELLITE RADAR SENSING DATA v * 'EOPHYS 2ES  VOL   PP n    - 2 $RINKWATER  2 (OSSEINMOSTAFA  AND 3 0 'OGINENI  h# 
 MODE TRANSMISSION LINES 0HOTOGRAPH COURTESY OF 2AYTHEON #OMPANY  . ££°Ón  2!$!2 (!.$"//+  &)'52%    'A!S --)# PROCESSING MAKES USE OF DEPOSITION AND ETCHING TECHNIQUES  TO FIRST DEFINE THE ACTIVE CHANNEL REGION OF THE TRANSISTOR n   FOLLOWED BY THE DEPOSITION OF  METALS  DIELECTRIC LAYERS  AND RESISTIVE LAYERS FORMING THE PASSIVE COMPONENTS n  4HEN  THICK METAL INTERCONNECTS   ARE INTRODUCED  FOLLOWED BY BACKSIDE PROCESSING TO CONNECT 2& GROUND TO THE TOPSIDE COMPONENTS n  %0)4!8)!, ,!9%23 -%3! %4#( !.$ /89'%.  )-0,!.4 &/2 )3/,!4)/. /(-)# -%4!, 0!44%2.).'  $%0/3)4)/. !.$ !,,/9 % 
 This technique has sometimes been referred to as ambiguity avoidance. For some sets of parameters, ambiguities cannot be avoided by using a radar with a single radiated beam. The use of multiple beams solves this problem. 
 One version of a clutter-lock MTI is TACCAR, which stands for time-averaged-clutter  coherent airborne radar.8 Although the name was originally applied to a particular airborne  MTI radar system developed by MIT Lincoln Laboratory, it continues to be used to refer to  the clutter-lock technique that was the special feature of that system. The name is even  retained when the technique is applied to a shipboard radar or when the radar is on land and  used for the compensation of moving clutter. The chief feature of TACCAR is the use of a  voltage-controlled osci11ator arranged in a phase-lock loop. 
 25. Siegel. K. 
 4 Apparent relative dielectric constant versus  moisture content (Richfield slit loam) ( after J. R. Lundien42) *  Angle of reflection equals angle of incidence. 
 MENTv 4HIS INDICATES THE LEVEL CORRESPONDING TO THE AVERAGE OF THE OPTIMUM 3#2  CURVE ACROSS ONE DOPPLER INTERVAL AND MAY BE CONSIDERED AS A FIGURE OF MERIT FOR A MULTIPLE 
 It is with much pleasure that I acknowledge the contributions of the individual chapter authors. I enjoyed working with these talented radar engineers and having the opportunity to learn so much from my associa- tion with them. A handbook such as this exists only because of the dedicated efforts of the many experts who took the time and energy to . 
 (7.34)  shows that the maximum gain corresponds to a wavelength  (7.35)  At this wavelength the gain will be 4.3 dB below what it would be in. the absence df errors. The  maximum gain is then  Pa (D) 2  Gmax = 43 £ (7.36)  The gain of an antenna is thus limited by the mechanical tolerance to which the surface can be  constructed and maintained.102 The most precise reflector antennas seem to be limited to a  precision of not much greater than about one part in 20,000, which from Eq. 
 3PECIFIC )NTEGRATED #IRCUITS !3)#S   WHICH ARE CUSTOM DEVICES DESIGNED TO PERFORM A PARTICULAR FUNCTION 4HE USE OF !3)#S ALLOWED $30 SYSTEMS TO BECOME VERY SMALL WITH HIGH PERFORMANCE (OWEVER  THEY WERE AND STILL ARE  DIFFICULT AND EXPENSIVE TO DEVELOP  OFTEN REQUIRING SEVERAL DESIGN ITERATIONS BEFORE THE DEVICE WAS FULLY OPERATIONAL )F AN !3)# 
 Radford: Review of United Kingdom Radar, IEEE Trans., vol. AES-20, pp. 506-520, September 1984. 
 It is not  suitable without modification for airborne radar because  of the effect of atmospheric-pressure changes on the gap.  There is a rather more elegant version known as the  triggered gap, in which the discharge takes place between  a metal cathode and a hollow tubular anode, usually of  molybdenum. The gap is set up so that normally it  will just not ‘strike’ until a trigger electrode (usually a  rod in the centre of the hollow anode) is connected, thus  closing the switch. 
 Beams of this type are of particular interest since they are easily generated. They may be used for transmission in a system where the receiving antenna has a cluster of simultaneous beams, or, as previously dis- cussed, they may be used in a search system to reduce the number of angular cells in regions of shorter range. Monitoring. 
 TER CANCELLATION  AND THE HARDWARE STABILITY LIMITATIONS OF THE RADAR 4HIS CHAPTER WILL DISCUSS THE MOTION EFFECTS AS WELL AS THE PERFORMANCE OF VARIOUS PROCESSING TECHNIQUES Î°{Ê * /", Ê "/" Ê  Ê //1 
 D" BANDWIDTH IS BARELY   AND ITS PERFORMANCE DETE 
 Klensch: Harmonic Radar Helps Autos Avoid Collisions, IEEE Spectrtrm, vol. 10,  pp. 38-45, May, 1973. 
 Introduction For many applications of synthetic aperture radar (SAR), the images can be adversely a ﬀected by sidelobes, especially in the case of strongly scattering targets with weak targets nearby, such as in a harbour with ships and containers. Hence, it is often desirable to suppress the sidelobes in order to improve image quality. Several methods have been proposed to do this. 
 Electron. 2000 ,22, 392–397. 11. 
 Moreno, and W. J. McBride, Jr.: Methods of Increasing Bandwidth of High Power  Microwave Amplifiers, IRE WESCON Coriv. 
 Scholnik and J. O. Coleman, “Integrated I-Q demodulation, matched filtering, and symbol- rate sampling using minimum-rate IF sampling,” in Proc. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter. 15.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 In formulation 1, sometimes called the small-perturbation method (SPM)  and asso - ciated most often with the work of Rice,94 the surface displacements are assumed  everywhere  to be much smaller than the radar wavelength, so the method is directly  applicable only to such cases as HF scattering with wavelengths of tens of meters,  at low to intermediate wind speeds, and with waveheights of a few meters at most. 
 These short water waves are known as capillary waves. An X-band radar when viewing large  swell waves at low grazing angles in the absence of wind would receive little or no back­ scatter since there would be no capillary waves present, even though the swell might be  large. As soon as wind appears, capillaries are formed, and the X-band radar will see back­ scatter since water waves are now present that are resonant to the X-band wavelength. 
 HORN       &OUR 
 In an S-band (3000 MHz) radar, for example, the plumbing losses might be as follows:  100 ft of RG-113/U Al waveguide transmission line (two-way)  Loss due to poor connections (estimate)  Rotary-joint loss  Duplexer loss  Total plumbing loss 1.0 dB  0.5 dB  0.4 dB  1.5 dB  3.4 dB  Beam-shape loss. The antenna gain that appears in the radar equation was assumed to be a  constant equal to the maximum value. But in reality the train of pulses returned from a target  with a scanning radar is modulated in amplitude by the shape of the antenna beam. 
 VIDE GOOD OVERALL GUIDES FOR ROUTINE 2#3 TESTING   'ENERAL 2EQUIREMENTS  4HE MOST IMPORTANT REQUIREMENT FOR 2#3 MEASURE 
 Sens. , vol. 31, pp. 
 This switch comprised a soft rhumbatron, which was placed a quarter wavelength from the T junction, shown in ﬁgure 3.5. The soft rhumbatron, also known as a soft Sutton tube, was a resonant cavity, similar to that used in a klystron, that was ﬁlled with water vapour at about 6 mm pressure. The cavity was heated to maintain the correct vapour pressure. 
 60. Cady, W. M., M. 
 TEM CONSISTING OF A PENCIL 
 OFILTER IMPROVEMENT FACTOR (dB) . 77.3 TIMEGATING Time gating of the receiver permits blanking of transmitter leakage and its noise sidebands, elimination of excess receiver noise from competing with the signal, range gating for target tracking, and true range measurement, provided the am- biguity can be resolved. Transmitted-Pulse Suppression. 
 The role of theory is to aid in interpreting these measurements and to suggest  how they may be extrapolated.FIGURE   16. 2 Ground area and projected area ch16.indd   3 12/19/07   4:54:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters.  SOLID-STATE TRANSMITTERS  11.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 for the switching modes is defined by the manner in which the transistor is biased  and how the waveshape of current and voltage is manipulated. 
 - - 
 BAND CLUTTER DATA FROM DIFFERENT SOURCES FOR A NOMINAL WIND SPEED OF   KN A  VERTICAL POLARIZATION AND  B  HORIZONTAL POLARIZATION  BASED ON DATA FROM ( -ASUKO ET AL   .2, &2  - ) 3KOLNIK  AND & % .ATHANSON  .   3%! #,544%2  £x°££ SEA CLUTTER OVER A RANGE OF GRAZING ANGLES DOWN TO  n 4HE CURVES REPRESENT THE  CENTERS  OF o  D" BANDS THAT CONTAIN THE MAJOR RETURNS FOR THE THREE HIGHER FREQUENCIES ,  #     AND 8 BANDSTHE 5(& RETURNS WERE A FEW DECIBELS LOWER  AND WIND SPEEDS ABOVE  ABOUT  KT 4HE MAJOR DIFFERENCES  IN SEA CLUTTER FOR THE TWO P OLARIZATIONS ARE SEEN TO  LIE IN THE RANGE OF GRAZING ANGLES BETWEEN ABOUT  n AND n  WHERE THE HORIZONTALLY  POLARIZED RETURNS ARE SMALLER 4HIS DIFFERENCE IS FOUND TO BE EMPHASIZED AT BOTH LOWER WIND SPEEDS AND LOWER FREQUENCIES 4HE CROSS SECTIONS APPROACH EACH OTHER AT HIGH ANGLES  n  AND  FOR THE HIGHER MICROWAVE FREQUENCIES  AT LOW ANGLES   n  AS WELL  )N FACT  FOR GRAZING ANGLES LESS THAN A FEW DEGREES AND MODERATE TO STRONG WIND SPEEDS  OBSERVERS HAVE REPORTED THAT AT 8 BAND AND AT THE HIGHER SEA STATES THE HORIZONTALLY POLARIZED RETURNS CAN EXCEED THE VERTICALLY POLARIZED RETURNS    4HE .2, &2 SYSTEM PERMITTED TRANSMISSION AND RECEPTION ON ORTHOGONAL POLAR 
 357. 77. A. 
 BAND WAVEFORMS AT SIMILAR ALTITUDES AND AIRCRAFT VELOCITIES 4HE RANGE DIMENSION REPRESENTS THE UNAMBIGUOUS RANGE INTERVAL  2 U  AND  THE FREQUENCY DIMENSION REPRESENTS THE 02& INTERVAL  WITH THE MAIN 
 Sletten and J. C. West, “Radar investigations of breaking water waves at low grazing angles  with simultaneous high-speed optical imagery,” Radio Sci ., vol. 
 LATION IS APPLIED THAT TRANSFORMS THE hSHORT TIME  LARGE BANDWIDTHv NATURE OF THE ORIGI 
 CALLY INCREASING OR DECREASING  THE WAVEFORM IS SIMPLY A STEPPED APPROXIMATION TO AN ,&-  WHICH HAS A RIDGE IN ITS AMBIGUITY FUNCTION &IGURE   )N ORDER TO APPROACH A THUMBTACK 
 14–19 of Farina,34 where  the important role played by a radar with low sidelobe antennas is also noted. Today  the use of computer programs for predicting radar performance under jamming, clut - ter, and chaff, and in the presence of various refined propagation models is well estab - lished: there are programs developed in house by individual radar companies196 or  available on the market.197 The Radar Work Station (RWS) is an example of a developed in-house program196;  RWS originates from the modeling and simulation activities carried out for prediction  of radar performance in several scenarios. One main objective of RWS is to provide  the radar analyst or system designer with a friendly but comprehensive toolkit for  prediction of radar performance based on well recognized, flexible, and documented  mathematical models. 
 ERROR  DETECTORS DESCRIBED IN #HAPTER  OF 3HERMAN .ORMALLY   P IS EITHER n OR n WHEN THE RADAR IS PROPERLY ADJUSTED  AND THE ONLY  PURPOSE OF THE PHASE 
 PASS ANALOGUE  FILTER CAN BE USED (OWEVER  DEPENDING ON THE NUMBER OF SAMPLES THAT HAVE BEEN AVER 
 DELAY CANCELERS HAVE WIDER CLUTTER REJECTION NOTCHES THAN SINGLE 
 FIELD STRENGTH OF THE SCATTERED WAVE AT THE RADAR 4HE DERIVATION OF THE  EXPRESSION ASSUMES THAT A TARGET EXTRACTS POWER FROM AN INCIDENT WAVE AND THEN RADI 
 .J  The decay of the visual information displayed on the CRT should be long enough to allow  the operator not to miss target detections, yet short enough not to allow the information  painted on one scan to interfere with the new information entered from the succeeding scan.  However, there is usually not sufficient flexibility available to the CRT designer to always  obtain the desired phosphor decay characteristics. The brilliance of the initial" flash" from the  CRT phosphor may be high, but the afterglow is dim so that it is often necessary to carefully  control both the color and the intensity of the ambient lighting to achieve optimum seeing  conditions. 
 98. J. R. 
 Figure 16.35 shows the two-channel amplifier onthe left, with the delay-line box inthe middle, and the video-modulated oscillator and amplifier fordriving the delay line ontheright. 16.20. Delay-line Trigger Circuits.-For proper cancellation the PRF oftheradar transmitter must match thesupersonic delay to~ofa pulse length. 
 65. Radford. M. 
 Gain, Directivity, and Effective Aperture. The ability of an antenna to concentrate energy in a narrow angular region (a directive beam) is described in terms of antenna gain. Two different but related definitions of antenna gain are directive gain and power gain. 
 47. L. B. 
 BANDWIDTH PRODUCTS  2ADAR EQUIPMENT DISTORTION SOURCES ALSO ESTABLISH LIMITATIONS ON ACHIEVABLE TIME  SIDELOBE LEVELS AND ARE DISCUSSED BY +LAUDER ET AL  AND #OOK AND "ERNFELD 4HE  METHOD OF PAIRED 
 Thus, the map  is built up in a recursive manner. About 10 to 20 scans are required to establish steady-clutter  v2lues. As rain moves into the area, or as propagation conditions result in changing ground-  clutter levels, the clutter map changes accordingly. 
 LINE PHASE BIT &)'52%   $IGITAL FERRITE PHASE SHIFTER USING  TOROIDS AFTER , 3TARK  .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°xÎ TO CONTROL EACH BIT INDIVIDUALLY /THER PHASE SHIFTERS USE A SINGLE TOROID AND A SINGLE  DRIVER  )N THIS CONFIGURATION  THE PHASE SHIFTER IS LATCHED ON A MINOR HYSTERESIS LOOP  BY ONLY PARTIALLY MAGNETIZING THE FERRITE 4HE DISTINCT ADVANTAGE OF THIS TECHNIQUE IS THAT ANY NUMBER OF BITS MAY BE IMPLEMENTED WHILE USING ONLY A SINGLE TOROID 4HEY HAVE THE ADVANTAGE OF LOW LOSS AND RELATIVELY HIGH POWER OPERATION $EVICES THAT HAN 
 UHFradar(A.=70cm)atzerodegreesgrazingangleresponds towaterwavesoflength 35cm.Theseareknownasgrauitywaves. Theeffectofthelargewaterwavesistocauseatiltingofthescattering surfaceofthe smallerwaterwaves,asinFig.13.6.Theradarwavelengths areusuallytooshorttobe responsive totheselongwaterwaves,buttheeffectofsuchwavesisnotedbythetilting ofthesmallerwaterwaveswhichareresonant withtheincident radarenergy.Thetilting effectofthelargewavesisespecially important atlowgrazinganglessincethegrazingangle isdetermined notonlybytheangletheradarenergymakeswiththemeanseasurface,but alsobytheangleoftheresonant wavesthatrideonthelargewavestructure. Thecomposite-model theoryofseaclutterseemstoaccount fortheexperimental results obtained withverticalpolarization betterthanwithhorizontal polarization. 
 Anequivalent result,withlesscomputation, istoapplydYllllmic programming, amethodfordetermining theoptimum solution toamultistage problem by optimizing eachstageoftheproblem onthebasisoftheinputtothatstage.Asappliedto arrays,thevariousstagesofdynamic programming involvetheselection ofthespacings of eachelementorpairofsymmetrically placedelements. Theapplication ofdynamic program­ minghasbeensuccessfully appliedtothedesignofonedimensional (linear)unequally spaced array.Although thecomputations required arefarlessthanfortotalenumeration, thereisa practical limittothenumberofelements inthearraythatcanbetreatedbythismethod. Theothertechnique, densitytaper,isapplicable tothedesignofeitherlineararraysorto largeplanararrays.Consider auniformgridofpossibleelementlocations with~qual spacing. 
 The heavy line in Figure 6.2 represents the desired signal and shows the variation  of normalized output frequency ( H – L)/H with normalized input frequency L/H.  All other lines on the chart represent the unwanted spurious signals. To simplify  use of the chart, the higher input frequency is designated by H and the lower input  frequency by L. 
 241–263, January–July 2003. 180. G. 
 As previously mentioned, when Wiley first  conceived of the concept that we now call SAR, he termed it doppler beam sharp - ening . Wiley explained it as follows: “I had the luck to conceive of the basic idea,  which I called Doppler Beam Sharpening (DBS), rather than Synthetic Aperture  Radar (SAR). Like all signal processing, there is a dual theory. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 3.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 This suggests7,13 that a correction signal in the reverse sense to ∆G2(q ) be applied,  as shown in Figure 3.14 c. 
 FED PHASED  ARRAYS COMPARE THE OUTPUT OF HALVES OF THE APERTURE AND FALL INTO THE CLASS OF PHASE 
 [ CrossRef ] 19. Lee, H.; Cho, S.-J.; Kim, K.-E. A ground-based Arc-scanning synthetic aperture radar (ArcSAR) systemand focusing algorithms. 
 The construction of the Lungui road started in March 2011. It was opened to tra ﬃc segmentally during the construction process, and the whole route o ﬃcially opened to tra ﬃc in January 2015. The Lungui Highway connects Longzhou Road, Nanguo Road, and Hengjiu Road northward, becoming one of the most important connection channels between the Shunde west district and the three main routes (from south to north) in Shunde Central City. 
 TIME PROCESSING #ARRARA   2ICHARDS  AND +LEMM  2ANGE 2ESOLUTION  3TRICTLY SPEAKING  3!2 REFERS TO A METHOD FOR IMPROVING  CROSSRANGE RESOLUTION  NOT RANGE RESOLUTION (OWEVER  BECAUSE FINE RANGE RESOLUTION IS SO NECESSARY TO A SUCCESSFUL 3!2  AND ALSO BECAUSE OF AN ANALOGY BETWEEN RANGE AND CROSSRANGE RESOLUTION  WE DISCUSS RANGE RESOLUTION BRIEFLY HERE &INE RANGE RESOLUTION IS ACHIEVED BY TRANSMITTING AND RECEIVING RADAR WAVES CHAR 
 TO 
 C. Poggio: Devel- opments in Radar Imaging, IEEE Trans., vol. AES-20, pp. 
 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4   blind folio 4.54 ch04.indd   54 12/20/07   4:54:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 (Copyright 1967, IEEE; from Ref. 18.} window integrator. The optimal values for log-normal interference were calcu- lated by Schleher19 and are M = 3, 8, and 25 and.N = 3, 10, and 30, respectively. 
 4.Schafer,C.R.:Phase-selective Detectors, Electronics, vol.27,no.2,pp.188-190, February, 1954. 5.Greenwood, I.A.,Jr.,J.V.Holdam, Jr.,andD.Macrae,Jr.(eds.):..Electronic Instruments," MIT Radiation Laboratory Series,vol.21,pp.383-386, McGraw-Hili BookCompany, NewYork,1948. 6.Palma-Vittorelli, M.M.,M.U.Palma,andD.Palumbo: TheBehavior ofPhase-sensitive Detectors, Nuovocimento,vol.6,pp.1211-1220, Nov.1.1957. 
 BER !LL PARAMETERS ASSOCIATED WITH A GIVEN TRACK ARE REFERRED TO BY THIS TRACK NUMBER 4YPICAL TRACK PARAMETERS ARE THE FILTERED AND PREDICTED POSITION VELOCITY ACCELERATION WHEN APPLICABLE  TIME OF LAST UPDATE TRACK QUALITY SIGNAL 
 In this chapter, emphasis will be on the more commonly used single antenna and, in particular, on the widely used reflector antennas. Phased array antennas are covered in Chap. 7. 
 R. Hendrikson, “Comparisons of target detection in clut - ter using data from the 1993 FOPEN experiments,” Proceedings SPIE , vol. 2230, p. 
 11.3, and can be comparable to  the fixed error as given by Eq. (3.14).  Other errors might be introduced in the CW radar if there are uncontrolled variations in  the transmitter frequency, modulation frequency, or frequency excursion. 
 Radar System Engineering  Chapter 6 – Radar Receiver Noise and Target Detection  34     Cosmic noise and atmospheric absorption noise,   Increase of the noise figure due to losses and attenuation of the input systems  (antenna, waveguide, switch, circulator, etc.),   Effective noise temperature of the receiver (amplifier, mixer, etc.).   Figure 6.6 shows the individual contributions with their iden tifiers.      Figure 6.6  Contributions of system noise temperature     The noise temperature is calculated exactly as the noise figure as a contribution of the indivi d- ual stages divided by the product of the gains G i of all preceding stages i. 
 9.1 INTRODUCTION Since World War II both radar and electronic warfare (EW) have achieved a very high state of performance.1'2 Modern military forces depend heavily on electro- magnetic systems for surveillance, weapon control, communication, and naviga- tion. Electronic countermeasures (ECM) are likely to be taken by hostile forces to degrade the effectiveness of electromagnetic systems. As a direct conse- quence, electromagnetic systems are more and more frequently equipped with so-called electronic counter-countermeasures (ECCM) to ensure effective use of the electromagnetic spectrum despite an enemy's use of EW actions. 
 (9.3)] is essentially related to the real-time estimation of M and R and to the inversion of M. Several processing schemes have been conceived which may be classified in two main categories: (1) closed-loop techniques, in which the output residue (connection a of Fig. 9.2) is fed back into the adaptive system; and (2) direct-solution methods, often referred to as open-loop, which operate just on the incoming signals VM and V. 
 This fortuitous situation is caused by conic distortion , which is inherent in any  phased array antenna. However, when the array normal is not normal to the baseline,  or when the receiving antenna is mechanically steered or scanned, qR is not measured  directly. Often DOA measurements are taken in—or converted to—azimuth and eleva - tion angles referenced to an x-y-z  coordinate system centered at the receive site, where  z is co-linear with the local vertical. 
 92–99, 1952. 20. E. 
 However, H 2SM k III and most subsequent models operated at 3 cm, which provided better angular resolution and hence better ground mapping quality. H 2S Mk III was operational with the RAF Bomber Command Path ﬁnder Force by December 1943 but ASV developments based on H 2S in the UK remained at 9 cm. ASV operation at 3 cm was considered and production of 3 cm equipment, based on H 2S Mk III was being planned in October 1943. 
 9. Schelkunoff. S. 
 When these loops were parallel to the axis of the waveguide, the side arm B(seeﬁgure 4.4) was effectively a wavelength long and since it was closed at its far end the effect was to produce a short circuit across bb. The side arm Aon the other hand was 3/4 wavelength long and appeared as an open circuit at the plane aa. Therefore, the effect at plane AAwas that of high impedance. 
 OF 
 With the elements spaced by X/2 (X = wavelength) to avoid the generation of multiple beams (grating lobes), the number of radiating elements N for a pencil beam is related to the beamwidth by __ 10,000N «O*)2 100QB^-T=VN where 6# is the 3 dB beamwidth in degrees. The corresponding antenna gain, when the beam points broadside to the aperture, is GO ^ TtNl] ~ TtNj]iJ\a where TJ accounts for antenna losses (i}L) and reduction in gain due to unequal weighting of the elements with a nonuniform amplitude distribution (j\a). When scanning to an angle 60, the gain of a planar array is reduced to that of the pro- jected aperture: G(B0) * irTVifi cos 60 . 
 TION TO SURFACE MEAN SLOPE  AND THE TENDENCY OF THE MINIMUM RANGE MEASUREMENT TO HOP FROM ONE ELEVATED REGION TO ANOTHER WITHOUT THE CONTROL OR KNOWLEDGE OF THE DATA ANALYST  "EAM 
 TIVELY LOW ORDER AND MAY PRODUCE STRONG OUTPUTS FROM THE MIXER 2& FILTERING IS ALSO IMPORTANT AS IT REDUCES OUT 
 TheAIDconverter hasbeen,inthepast,oneofthecriticalpartsoftheMTIsignal processor. Itmustoperateataspeedhighenoughtopreserve theinformation contentofthe radarsignal,andthenumberofbitsintowhichitquantizes thesignalmustbesufficient forthe precision required. ThenumberofbitsintheAIDconverter determines themaximum im­ provementfactor theMTIradarcanachieve.a.75.76 Generally theAIDconverter isdesigned to coverthepeakexcursion ofthephasedetector output.Alimitermaybenecessary toensure '" this.AnN-bitconverter dividestheoutputofthephasedetector into2N-1discreteintervals. 
 2ATIO 3.2   3.2 IS THE RATIO OF RMS SIGNAL AMPLITUDE TO RMS  !$ CONVERTER NOISE POWER &OR AN IDEAL !$ CONVERTER  THE ONLY ERROR IS DUE TO QUAN 
 ING FUNCTIONS  AND IN MODERN RADAR SYSTEMS  THESE FUNCTIONS ARE PERFORMED USING DIGITAL SIGNAL PROCESSING ON THE RECEIVER OUTPUT  ) AND 1 DATA 4HESE FUNCTIONS ARE  DISCUSSED IN OTHER CHAPTERS OF THIS HANDBOOK 4HE PURPOSE OF THE FILTERING WITHIN THE RECEIVER IS TO REJECT OUT 
 K. Goward: "Aerials for Centimetre Wavelengths," Cambridge University Press.  New York, 1950. 
 The greater the signal-to-noise ratio and the steeper the slope of the error signal in the  vicinity of zero angular error, the more accurate is the measurement of angle. The error-signal  slope as a function of the squint angle or beam crossover is shown in Fig. 5.1 l. 
 CENTERED COORDINATES3TATE PROPAGATION IS LINEAR NO PSEUDO 
 Thus, the expression (11) deﬁnes the asteroid’s complex image with amplitude mod [ˆS(k,ˆp)], and phase arg[ˆS(k,ˆp)]. It is worth noting that the Doppler bandwidth and, respectively, Doppler resolution or cross range (azimuth) resolution of the ISAR signal are limited by the ﬁxed main pulse repetition period equal to 0.033 s, and apparent rotation angle between the vector velocity and mass-center’s line-of-sight vector in case rectilinear movement of the asteroid. 7. 
 across the series feed may be applied for an entire column if all the feeds have the same phase characteristics. A large array requires many electronic phase-shifter drivers and very complex wiring to provide control signals and energy. The problem is complicated by the relatively close spacing of elements in the array. 
 8.2). A similar condition for a synthetic aperture antenna is that the  distance traveled by the radar between pulse transmissions should be less than 1/2. (The  factor of 4 appears here for the same reason it was included in Eq. 
 It is easier to ensure the accomplishment of tlie  weapon system's mission than to guarantee that operation of a single radar will not be  degraded. This larger and more important goal, that of fulfilling a military mission, is what  sliould guide tile niilitary systerl~s planrler arid the radar systems designer. Tliis broader. 
 20.6 is of fundamental importance to many HF radar applications, including ship  detection, remote sensing (see following section), waveform selection, and other radar  management functions. For example, Figure 20.11 shows a measured doppler spec - trum and, superimposed, representative estimates of the magnitudes of the echoes that  might be received from a number of different ship types for the same radar design and  waveform parameters. Also shown, at left, are the speed bands within which the ship  echoes would be obscured by the clutter. 
 The scatterometer is fully polarized (HH, HV , VH, and VV). Peak transmitted  power is ∼250 W, pulse length is 1 ms, sufficient to support sea surface s  0 over the  range 0 dB to –40 dB. Resolution is modest, at ∼150 km. 
 Discrete changes inindexofrefraction approximate acontinuous variation. Inoneexample ofaLuneburg lens10concentric spheri­ calshellsarearranged onewithintheother.54•55Thedielectric constant oftheindividual shells variesfrom1.1to2.0inincrements of0.1. Point source fl.::------l>-------+-.---~ Figure7.21Luneburg-Iens geometry showing raysfrom apointsourceradiated asaplanewaveafterpassage through thelens.. 
 If the labeled area is found to be a part of a larger object, then the same location in the mission image is checked for the same object. In thecase of two similar objects around the same location, it can be assumed that the detected object is a false negative and excluded from the difference map. After these two methods are performed, the 270. 
 The fewer the number of elements used, the tighter the tolerance becomes. The individual effects of phase and amplitude errors and failed elements are sum - marized in Figure 13.18.75 The resultant rms sidelobes are referenced to the gain of a  single element so that the curve can be used for any number of elements with indepen - dent errors. For example, a 5 ° rms phase error will produce an rms sidelobe level that  is approximately 21 dB below the gain of an element. 
 A decrease in  the resolution of the clutter map to counter the rapidly changing clutter residue will  preclude much of the interclutter visibility (see later in this chapter), which is one of  the least appreciated secrets of successful MTI operation. MTI radar must work in the environment that contains strong fixed clutter, birds, bats  and insects, weather, automobiles, and ducting. The ducting, also referred to as anoma - lous propagation , causes radar returns from clutter on the surface of the Earth to appear Chapter 2 ch02.indd   1 12/20/07   1:42:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Abbott: Oxygen and Water Vapor Absorption of Radio Waves in the Atmosphere, Geofis. Pura AppL, vol. 37, pp. 
 ARRAY 
 r  Table 13.1 World Meteorological· Organization sea  state  ····················--- Wave height  Sea stale Feet Meiers Descriptive term  0 0 0 Calm, glassy  I 0 i 0-0.1 Calm, rippled  2 ! ·· 1 j 0.1 0.5 Smooth, wavelets  _:\ 2-4 0.6-1.2 Slight  4 4-R l.2-2.4 Moderate  5 8·-13 2.4-4.0 Rough  6 13-20 4.0-6.0 Very rough  7 20 JO 6.0 9.0 High  8 30-45 9.0-14 Very high  9 over 45 over 14 Phenomenal . 476 INTRODUCTION TO RADAR SYSTEMS  Variation with frequency and polarization. From Fig. 
 ] (2.59) If the signal does not reach the full excursion of the A/D converter, which is normally  the case, then the quantization limit on I is proportionately more severe. For example,  if the system is designed so that the mean level of the strongest clutter of interest is   3 dB below the A/D converter peak, the limit on I would be 20 2 1 0 7510⋅ − ⋅ log [ ( ) . ]N. 
 Thus, the spatial variance of the Doppler rate and the derivative of the Doppler rate should be estimated and compensated.   (a) (b)  Figure 6. The spatial variance of the Doppler parameters. 
 Very good navigation can beperformed bycomparing the PPI with achart and taking therange and bearing ofsufficient identifiable points shown onthe radar todetermine the location oftheship. The organization required beyond the radar indicator consists inthis case ofvery little more than theship’s navigator. The problem ofcreating themost efficient organization fortheuseof radar data, ineach functional situation involving radar, isavery com- plicated one. 
 LIMITED ENVIRONMENT &OR (273  DIFFERENT LINEAR 
 When the two thresholds are optimized, it has been  found that a second transmission is employed in about four percent of the beam positions.'0 It  is claimed that a power saving of from 3 to 4 dB can be obtained as compared with uniform  scanning.42  j  10.5 DETECTOR CHARACTERISTICS  The portion of the radar receiver which extracts the modulation from the carrier is called the  detector. The use of this term implies somewhat more than simply a rectifying element. It  includes that portion of the radar receiver from the output of the IF amplifier to the input of  the indicator or data processor. 
 D. Ostroff et al ., Solid-State Transmitters, Norwood, MA: Artech  House, 1985 .) ch11.indd   23 12/17/07   2:25:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 18, 1974. 22. Cantafio, L. 
 Land returns were also reduced. It was also reported that signals normally swamped by sea returns were easily distinguished when the discriminator was used and that detection ranges were not signi ﬁcantly affected. It was also noted that a good operator manipulating gain and brightness without the discriminator could get equivalent results when homing on a target. 
 In this case, it is only necessary to be sure not to let the modulator begin pulsing the beam current during turn-on of the HVPS until the voltage is safely above the oscilla- tion range, which is typically somewhere between 60 and 80 percent of full oper- ating voltage. POWER FIG. 4.10 Rabbit-ear oscillations on the enve- lope of the RF output from a cathode-pulsed TWT amplifier. 
 LN   · ·M     WHERE .FU   NUMBER OF INDEPENDENT DOPPLER FILTERS IN THE UNAMBIGUOUS DOPPLER REGION  7    WIDTH IN DOPPLER FILTERS  OF THE CORRELATION WINDOW APPLIED TO DETECTIONS  FOLLOWING INITIAL DETECTION 0ROBABILITY OF $ETECTION  5SING THE  0&! PER RANGE 
 Tracking. and Navigation." W. T. 
 Probability of Detection. The probability-of-detection curves presented in Chap. 2 have been extended to include multilook detection criteria and are presented in a generalized fashion after Ref. 
 DIGITAL IMAGE SYNTHESIZER CAPABLE OF GENERATING FALSE 
 TO 
 AP-25, pp. 406–409,  May 1977. 13. 
 02& RANGE 
 West, J. M. Sturm, and A-J Ja: Low-Grazing Scattering from Breaking Water Waves Using  an Impedance Boundary MM/GTD Approach, IEEE Trans. 
 Reflection ofradiation from the earth’s surface greatly influences theradar beam characteristics inelevation angle, and such effects must begiven careful consideration. Over water, the reflection coefficient is high forallwavelengths ofinterest forairsurveillance, and forvery small angles ofincidence itcan beassumed tobe100 per cent. Over land, thereflection coefficient varies markedly with detailed surface shape and with thecomposition oftheterrain, and ingeneral increases with increas- ing wavelength. 
 J. Zuckcr  (eds.), McGraw-Hill Book Co., New York, 1969.  137. 
 The 45 ° aspect geometry is of interest because the RCS in the  bistatic regions is larger than the monostatic RCS for most bistatic angles. The large  spike at b = 90° is the bistatic specular lobe, analogous to the monostatic specular lobe  in the broadside geometry. While Figure 23.8 shows the clear dependency of bistatic  RCS on both aspect and bistatic angles, it also serves to caution against attempts to use  oversimplified bistatic RCS models, especially in the bistatic region. 
   NO   PP n   .OVEMBER   , $URFEE AND 7 $ULL  h-02& )NTERPULSE 0HASE -ODULATION FOR -AXIMIZING $OPPLER #LEAR  3PACE v 53 0ATENT     3 (OVANESSIAN  h!N ALGORITHM FOR CALCULATION OF RANGE IN MULTIPLE 02& RADAR v  )%%% 4RANSACTIONS  ON !EROSPACE  %LECTRONIC 3YSTEMS  VOL !%3 
 Roberts and J. W. Wilson, “A proposed microburst nowcasting procedure using single   doppler radar,” J. 
 MOUNTING ON AIRCRAFT OR MISSIL ES )F THE SURFACE HAS A  LARGE RADIUS OF CURVATURE SO THAT ALL THE RADIATING ELEMENTS POINT IN SUBSTANTIALLY THE  SAME DIRECTION  THEN THE CHARACTERISTICS ARE SIMILAR TO THOSE OF A PLANAR ARRAY EVEN THOUGH THE EXACT $ POSITION OF THE ELEMENT HAS TO BE TAKEN INT O ACCOUNT TO CALCULATE  THE REQUIRED PHASE ! SMALL RADIUS OF CURVATURE IS FOUND WITH CYLINDRICAL OR SPHERICAL   ARRAYS USED FOR n  COVERAGE %LEMENTS ARE SWITCHED TO AVOID SECTIONS OF THE ANTENNA  WHERE THEY POINT AWAY FROM THE DESIRED BEAM DIRECTION $IFFICULTIES MAY BE ENCOUN 
 Figure 1shows a schematic diagram of the combined elements in the Kelvin rheological model. The rheological state equation of the Kelvin model can be written as [ 32]: ε=σc E(1−e−E ηt) (3) whereεdeﬁnes the strain related to the material and σcdeﬁnes a constant external load. When the post-construction operation stage of a highway starts, the external load mainly includes the gravity of the surface layer and the load of the tra ﬃc vehicles. 
 The “flopover” and the“scale-of-two” (Fig. 1315) aredireckoupled inboth directions insuch away astohave two stable states, and will remain ineither until disturbed intheproper manner. Intheflopover, 1Forsimplicity itcanbeassumed, asispractically always thecase, that thesupply voltage ismuch higher than thecutoff voltage andthat theplate re&tors aremuch smaller than thegridresisturs butlarge enough toabeorb most ofthepotential drop when inseries with asaturated tube.. 
 This amount of reverse-directed power is 2 dB greater than the RF input power arriving at that point even if the CFA has only 10 dB of gain. Although this does not seem to interfere with normal CFA opera- tion, it does require an isolator at the CFA input with 16 dB isolation, in this case, just to bring the VSWR seen by the previous stage down to 1.5:1. Matching. 
 V . C. Chen and H. 
 We do not switch it on,  moematly, when the radar is operational, but test it every  . SHORT, SHARP SHOUTS 4I  now and then to ensure that our time-base—our apparent  line of light on the CRT—is being covered by the light-  spot at a constant speed throughout. If there were any  variation in the speed a little thought will show that the  Cal spikes of light would not be evenly spaced like the  teeth of a comb, but would be closer in groups at one  part of the line than at another. 
 1.0  ~ 0.1 .,  ,,:; a.  b"'  0.01 Mie or resonance  region Optical  region  0.001 ..__ __ _,___-'--......,_.....,_....._ ............ ......,_ __ __. 
 q~< ,~ FIc+.9.28.—The thre~axis antenna mount oftheSCIradar. principle isthesame asmoving thefeed inanordinary paraboloid reflec- tor. The reflector forthis antenna isnot paraboloidal, however, but is astigmatic, having different focal lengths inthe horizontal and vertical planes because the points ofdivergence ofthe rays inthe feed differ in thetwo planes.. 
 The optimum bandwidth for angle tracking is range-dependent. A target with typical velocity at long range has low angle rates and a low SNR, and a narrower servo passband will follow the target with reasonably small tracking lag while minimizing the response to receiver thermal noise. At close range the signal is . 
 M4S is a software toolkit based on a modiﬁed composite surface model for numerical simulations of SAR imaging of oceanic surface current features [ 24–26], and it can simulate surface wave spectra modulated by spatially varying currents. Different wind ﬁelds, radar and platform parameters can be set to investigate their impact on SAR eddy features with the same ocean surface current ﬁeld induced by eddies. A ﬂow chart of the simulation process is presented in Figure 3. 
 Lewis.139)  7.4 SCANNING-FEED REFLECTOR ANTENNAS  Large antennas are sometimes difficult to scan mechaniGally with as much llexibility as one  might like. Some technique for scanning the beam of a large antenna must often be used other  than the hrute-force technique of mechanically positioning the entire structure. Phased array  antennas and lens antennas offer the possibility of scanning the beam without the necessity for  moving large mechanical masses. 
 Foradumped integrator. onewhicherasesthecontents oftheintegrator after Ilpulsesandstartsover,the efficiency isI 4 tanh(1l1'/2) f1=--,,--'----,~-'-:- Iltanhb'/2)(2.35a) (2.35b) (2.36)Anexample ofanintegrator thatdumpsisanelectrostatic storagetubethatiserasedwhenever itisread.Theefficiency ofanintegrator thatoperates continuously withoutdumping is [I-exp(-'11')]2P=---.--.--------- 11tanh(r/2) Themaximum efficiency ofadumped integrator occursforI'=0,butforacontinuous integra­ torlhemaximum efficiency occursforIl}'=1.257. 2.7RADAR CROSS SECTION OFTARGETS Theradarcrosssectionofatargetisthe(fictional) areaintercepting thatamountofpower which.whenscattered equallyinalldirections, produces anechoattheradarequaltothat fromthetarget;orinotherterms, powerreflected towardsource/unit solidangle 1E12 (J= incident powerdensity/4n =!~4nR2 E: whereR=distance between radarandtarget Er=reflected fieldstrength atradar Ej=strength ofincident fieldattarget Thisequation isequivalent totheradarrangeequation"'ofSec. 
 MISMATCHED CRYSTAL LAYERS ! VERY SIMPLIFIED DESCRIPTION  PORTRAYS AN !L'A!S  LAYER OVER AN )N'A!S CHANNEL ON A 'A!S SUBSTRATE FORMING A HIGH QUALITY TWO 
 Anderson, S. Kraut, and J. L. 
 141. T. Fujita, “The DFW microburst,” Satellite and Meteorology Research Project, Department of  the Geophysical Sciences, University of Chicago, 1986. 
 LOOKINGv   WITH  CROSSRANGE RESOLUTION ^ 2K$ $OPPLER "EAM 3HARPENING $"3   !S PREVIOUSLY MENTIONED  WHEN 7ILEY FIRST  CONCEIVED OF THE CONCEPT THAT WE NOW CALL 3!2  HE TERMED IT  DOPPLER BEAM SHARP 
 LOOP METHODS CAN ALSO BE IMPLEMENTED BY USING DIGITAL CIRCUITRY IN WHICH CASE  THE CONSTRAINTS ON NUMERICAL ACCURACY ARE GREATLY RELAXED  AND THE TOTAL NUMBER OF ARITHMETIC OPERATIONS IS MUCH REDUCED BY COMPARISON WITH DIRECT 
 82. Ewell. G. 
 Di Nardo, U.: Adaptivity Criteria of a Modern Air Traffic Control Radar, Rir~iscu Trc.tricu S~~It~tricr  (Rome), vol. 2, no. 4, pp. 
 R.H.:ATheoryofTargetGlintorAngular Scintillation inRadarTracking. Proc.IRE.vol. 4I.pp.1778-1784, December. 
 The differ - ence between day and night scatter  from snow is even more pronounced  at 35 GHz, but the model does not  include 35 GHz because no data  exists between 17 and 35 GHz. Although no specific clutter  model has been developed for forests,  results from the Skylab RADSCAT  and Seasat scatterometer show  that the Amazon rainforest scatters  almost independently of the angle  of incidence even near vertical.120  The mean measured value at 33° was  −5.9 ± 0.2 dB at 13.9 GHz. Similar  results were found at C band.121  Observations with SIR-B, SIR-C,  and JERS-1 indicated that this lack  of angular variation of s 0 also is  present at 1.25 GHz.122,123 The models described above are  based on averages over very large  areas. 
   /CTOBER   ( ,EUNG  : (U  AND - "LANCHETTE  h%VALUATION OF MULTIPLE RADAR TARGET TRACKERS IN STRESSFUL  ENVIRONMENTS v  )%%% 4RANS  !EROSPACE AND %LECTRONIC 3YSTEMS   VOL   NO   PP n      " ( #ANTRELL  ' 6 4RUNK  AND * $ 7ILSON  h4RACKING SYSTEM FOR TWO ASYNCHRONOUSLY SCANNING  RADARS v .AVAL 2ES ,AB 2EPT     7 $ 3TUCKEY  h!CTIVITY CONTROL PRINCIPLES FOR AUTOMATIC TRACKING ALGORITHMS v IN  )%%% 2ADAR   #ONFERENCE    PP n  4 2 "ENEDICT AND ' 7 "ORDNER  h3YNTHESIS OF AN OPTIMAL SET OF RADAR TRACK 
 (Actual pulse widths can be much longer, especially if pulse  compression is used.) The lower bandwidth limit of 5 kHz is set by the desire to be able to  operate in the quieter" holes" of the HF spectrum. The wider the spectral width the less likely  that regions of the spectrum can be found without significant interference. Evetfif interference  is not a problem, the upper limit of spectral width, about 100 kHz, is set by the dispersive  nature of the ionosphere. 
 Pulse width thus affects t wo very important radar  system  capabilities - resolution and detection range.  These two  qualities are traded off against  each other.  Wider pulses  equate to longer -range radars  with less  resol ution, whereas  narrow  pulses equate to  finer resolution but shorter range. 
 A subaperture imaging scheme for wide azimuth beam airborne SAR based on modiﬁed RMA with motion compensation. In Proceedings of the 2014 IEEE Geoscience and Remote Sensing Symposium, Quebec City, QC, Canada, 13–18 July 2014; pp. 608–611. 
 14.11. The  relative amplitudes of the three echoes are in the ratio of 1, 2p and p2, where p = surface  reflection coefficient. A measurement of the time delay t0 along with the range R to the target  and knowledge of the height ha of the radar antenna yields the height of the target. 
 VELOCITY MOVING TARGET   
 SIGHT SYSTEMS IS THE IMPACT OF THE IONOSPHERIC PROPAGATION MEDIUM ON THE CHARACTERISTICS OF THE RECEIVED  INTERFERENCE 4HE IONOSPHERE IS STRATIFIED WITH DIFFER 
 In Section 5, a pulsar signal model as a time frequency grid and an algorithm of ISAR signal formation are described. In Section 6, a power budget, ISAR signal processing and asteroid image reconstruction are analytically described. In Section 7, results of a numerical experiment are provided and discussed. 
 increases only directly with the number of elements. The gain of a broadside array of isotropic  elernen ts is approximately  (Note that wllell imn = corlstallt. (;, = MN.) l'hen the nornlalized pattern of Eq. 
 The load is inserted in the  cathode lead, and the output is taken from across this  resistance. The gain is low, and the arrangement has  little merit as an amplifier, but the output circuit can  be made to have a low impedance, and is therefore  suitable for connecting to a transmission line. It acts,  in fact, as a transformer, with none of the difficulties  attending the use of transformers  for ‘pulses,’ such as the effects of |  internal capacity and resonances. 
 17–22, 1960. 71. E. 
 -8/2  ,1112  I (sin2 nfr)/n2f2 df nBr -sin nBr  ti -s·i-(--n·--B-t) + ( COS_1t_Bt---l-)/-1rBr (11.18)  . -R/2  where Si X fs the sine integral function defined by r (sin u)/u du. As Br -co, the product  0  t 2 2B fi ::::; --­ T for large Br  -·· ---8---------~  rron11nr,r•,1 ~-":It,.. 
 Unlike standard waveguide propagation, the cutoff wavelength for ducting  PROPAGATION OFRADAR WAVES451 havethesamecurvature astheearthitself,itwouldbepossible forinitiallyhorizontal raysto hendaroundthesurfaceofthe earth. FromEq.12.10,agradient d1l/dh=-1.57x10-7m-I willmaketheeffective earth'sradiusinfinitewhichallowsinitiallyhorizontal raystofollowthe curvature oftheearth.Undersuchconditions, theradarrangeissignificantly increased and detection beyondtheradarhorizoncanresult. Theabnormal propagation ofelectromagnetic wavesiscalledsuperrefraetio1l, trappi1lg, ductillY,orallomalollS l'rol'llyllt iml.Accordingtoonedefinition.25normalatmospheric refrac­ tiollcorresponds tothegradient dll/dlzvaryingfrom0to-0.787 X10-7m-I.orwhenthe effective earth'sradius(Eq.12.10)variesfromk=1tok=2.Superrefraction corresponds to dll/dlzfrom-0.787x10-7to-1.57 X10-7m-I•ork=2tok=00.Trapping, ordueting. 
 ARRIVAL !/!  AND POSSIBLY BURST RANGING ARE PERFORMED WITH THE PRIMARY RADAR APERTURE  AS SHOWN IN THE TOP PORTION OF &IGURE  (IGH 
 A' band, l~orizontal polari~ation. (Frott~ Kul: utul  Sprt~lrr,~~~oltrres~ J. Rrs. 
 Figure 3. Pulse Width versus Resolution   Pulse Power   Another consideration for the maximum range of a radar  is the  transmitted power. Peak power is a measure of the maximum  instantaneous power level in the pulse. 
 ARRAY  IMAGING  AND OVER 
 TO 
 TIPLES OF THE PULSE REPETITION FREQUENCY Ó°{Ê   1// 
 2ofVol. 11ofthe series,. 662 MOVING TARGET INDICATION [SEC.16.16 Equation (3), giving theallowable rate offrequency drift inthelocal oscillator, was based ontheassumption that thefrequency was changing ataconstant rate. 
 Onadais attherear oftheshelter sit the chief controller, who isresponsible forthe general operation ofthe station, and officers concerned with identification oftracks, liaison with antiaircraft artillery, Army, and Navy (asrequired), and other coordina-. SEC. 7.6] THE U.S. 
 This impedance isinparallel with thegrid resistor and the wiring capacity. The effective impedance ofthe grid resistor connection can beincreased bythe method shown onthe right inFig. 13”1 lb,since the drop inthegrid resistor isthereby reduced. 
  RADAR  DEVELOPED BY ,OCKHEED -ARTIN FOR THE 53 .AVY  IS AN EXAMPLE  OF AN !-4) RADAR SYSTEM UTILIZED FOR AN AIRBORNE EARLY WARNING RADAR MISSION +EY FEATURES OF THIS SYSTEM INCLUDE A SOLID 
 Further, HF antennas seldom achieve high front-to-back ratios, so the risk of  signal masking by backlobe clutter cannot be ignored. For linear arrays, offsetting the  transmit and receive array boresights is a moderately effective measure that must be  traded off against the concomitant reduction in main beam overlap. Linear arrays of  vertically polarized log-periodic antennas, vertical planar arrays of horizontal dipoles,  stacked Yagi antennas, elevated rhombic elements, linear arrays of tilted monopoles,  and a two-dimensional array of biconical antennas have all been used in skywave radar  transmit systems, in some cases, with backscreens to improve the otherwise mediocre  front-to-back ratios. 
 n°Ó{  2!$!2 (!.$"//+  !S THE DOPPLER SHIFT MOVES AWAY FROM ZERO  THE PEAK DECREASES AND THE CLOSE 
 AFCRC-TR-59-118(1), ASTIA Document 2ll499, pp. 8-17, April, 1959.  7 3. 
 Pettengill. G. H.: Radar Astronomy. 
 The reduction in rms angle and range target scintillation  may be approximated by dividing by the square root of n, where n is the number of  frequency steps provided. Reduction of Internally Caused Errors.  Angle errors caused by receiver ther - mal noise, as well as target scintillation, are minimized by maintaining the target  as closely as possible to the tracking axes. 
 The resulting sensitivity (noise-equivalent sigma-zero) is very good, –30 dB or better  for most modes. PALSAR’s host ALOS spacecraft is yaw-steered to maintain azimuth  antenna boresight pointing at zero doppler, which increases the likelihood of pass- to-pass interferometric coherence and simplifies (somewhat) SAR image formation  processing. The nominal data rate in most modes is 240 Mbit/s, which is downlinked  via Japan’s Data Relay Test Satellite (DRTS). 
 Three different kinds of support structures have been demonstrated to be useful in  RCS measurements. They are the low-density plastic foam column, the string suspen - sion harness, and the slender metal pylon. The echo from a plastic foam column arises  from two mechanisms. 
 Land  clutter can be so large that clutter echoes might enter the radar receiver via the antennd  482INTRODUCTION TORADAR SYSTEMS Thebackscatter fromiceathighgrazinganglesiscomplicated bytherelativeeaseof penetration ofradarenergyintotheice.Thereflection fromtheair-iceinterface maybe accompanied byareflection fromtheunderlying ice-water orice-·land interface. Thesereflec­ tionsfromthetwointerfaces, aswellasmultiple internalreOections, canresultinradarback­ scatterthatvarieswiththeicethickness, watercontentoftheice,andradarwavelength. The penetration properties ofradarenergyiniceandsnow,especially atUHForlowerfrequencies, canresultinseriouserrorsintheheightmeasurement ofradaraltimeters.67Undersome conditions,theremightbenoechofromthetopsurfaceoftheice,andiftheiceisthickenough theremightbenoreflection fromthebottom. 
 UNDERSTOOD  !TMOSPHERIC $UCTING  !NOTHER TOPIC IN SEA CLUTTER THAT HAS BEEN LITTLE EXPLORED  IS THE ROLE PLAYED BY  PROPAGATION EFFECTS  WITHIN THE ATMOSPHERIC BOUNDARY LAYER  LYING OVER THE SEA SURFACE 4HE EFFECTS OF ATMOSPHERIC ABSORPTION HAVE BEEN NOTED ABOVE IN CONNECTION WITH MILLIMETER 
 The construction ofsuch amagnetron-magnet combination, or“packaged magnetron” asitis frequently called, isshown inFig. 10.5. The cathode isusually sup- ported axially through iron pole pieces which extend quite close tothe IWa.1O.4.—TWO types ofmagnetron construction: (a)radial cathode andseparate mag- net;(b)axial cathode with attached magnet. 
 2. “Revised recommendations on performance standards for radar equipment,” Resolution  MSC.192(79), International Maritime Organization, London, 2004.  3. 
  SHAPED REFLECTOR WITH OFFSET FEED !IR 4RAFFIC #ONTROL 2ADAR  "EACON 3YSTEM !4#2"3  ARRAY IS MOUNTED ON TOP  #OURTESY  .ORTHROP  'RUMMAN  #ORPORATION . 
   #ALIBRATION IS IMPORTANT TO MINIMIZE ERRORS 7HEN MAXIMUM PERFORMANCE IS  REQUIRED  TIMELY ACCURATE CALIBRATION MUST BE PERFORMED 4HE PROCEDURE MAY REQUIRE UP TO FOUR HOURS TO FULLY STABILIZE THE RADAR SYSTEM &OR INSTRUMENTATION RADAR  WHERE THE TIME OF A TRACKING EVENT IS KNOWN  FINAL CALIBRATION IS PERFORMED JUST PRECEDING THE EVENT TO MINIMIZE DRIFT ERRORS °££Ê -1  ,9Ê"Ê-"1, 
 This radome ismade ofFiberglas laminate inasandwich construction. Its electrical transmission exceeds 88per cent forboth parallel and per- pendicular polarizations through anangle-of-incidence range of0°to70°. Figure 9.11 shows aradome covering anend-fire array. 
 6.1, vanes may be used, as in Fig. 6.2n. Slots  Ilave also bee11 eniployed. 
 P. Bollini, L. Chisci, A. 
 And, self  consistency constraints of the polarimetric precipitation covariance matrix impose  relatively strict bounds on the absolute reflectivity measurements, allowing one to  calibrate the reflectivity measurement and make improved rainfall rate estimates.128  For short wavelength radars, one must consider Mie scattering effects when measur - ing rainfall rate by reflectivity measurement. Lhermitte25 and Kollias et al.129 give an  analysis of Mie scattering and show that if the scattering is properly accounted, the  rainfall measurements are accurate. Polarimetric radars may be configured in different ways for different measure - ments. 
 Each radar set has itslimitations inrange and resolution. The maximum range islimited bymany factors, 1including the transmitted power, the receiver sensitivity, and the antenna gain. ]SeeChap. 
 When the first microwave PPI radar was installed inaircraft, careless navigators neglected their dead reckoning inthe belief that the radar would enable them todetermine their position whenever necessary. This procedure resulted ingetting lost with such regularity that radar was soon established asanadjunct todead reckoning, rather than asub- stitute forit. Toassist indead reckoning, particularly inaircraft navigation where high speed and frequent course changes make itdifficult, various forms. 
 Sensors 2019 ,19, 1701 coordinate is proposed. SAR data from different view angles is imaged in a uniform coordinate system. The resolution between images is the same, and the image is not deformed and scaled. 
 SATELLITE PATH OF THE ALTIMETERS FOOTPRINT  WHICH TYPICALLY IS  KMn KM WIDE  DETERMINED BY MEAN SEA STATE &LIGHT 3YSTEMS  +EY ATTRIBUTES OF SATELLITE RADAR ALTIMETERS ARE SUMMARIZED IN  4ABLE  3INCE   OCEANIC HEIGHT MEASUREMENT ACCURACY HAS IMPROVED  DUE PRIMARILY TO MORE EFFECTIVE MEANS OF ESTIMATING AND CORRECTING SYSTEMATIC ERRORS 0ERFORMANCE ALSO HAS BENEFITED FROM INNOVATIVE ONBOARD HARDWARE AND ALGORITHMS AND MORE PRECISE DETERMINATION OF THE RADIAL COMPONENT OF THE ORBIT 4HE *ASON 
 WARNING !%7  AIRCRAFT SHOWING ROTODOME  HOUSING THE ANTENNA .   !)2"/2.% -4)  Î°Î WHILE REVERSING COURSE  LARGE CRAB ANGLES WHEN HIGH WINDS ARE ENCOUNTERED  THE NEED  TO POSITION GROUND TRACK IN RELATION TO WIND  NONTYPICAL OPERATING SITUATIONS  AND OPERA 
 Cllapli~i: Ilrives for Steerable Antennas. Hydraulics versus Electro-  Mcchariics, " Desigri and Construction of Large Steera.ble Aerials," IEE (London) Cotlftrence Prrhli-  c-orinn no. 21, pp. 
 This is partly due to the large size of the clutter map cell relative to the radar resolu - tion. A finer-grain map with additional spreading would have a much better velocity  response characteristic. A potential problem with the type of amplitude clutter map described in this sec - tion is the fact that a large target flying in front of a smaller target may cause enough  buildup in the map to suppress the small target. 
 Sea clutter is not as strong and does not usually extend to as great  a range as does land clutter. Thus high-flying aircraft over the sea can be detected at long range  with relatively conventional radar with only a minimal MTI, or even with no MTI in some  cases. A more severe problem occurs 'when a seaborne radar must operate near land. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .576x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 68. 
 OF 
 Jeffrey Keeler and Robert J. Serafin National Center for Atmospheric Research* 19.1 INTRODUCTION Standard operational meteorological doppler radars have become familiar observa - tional tools to radar engineers as well as the general public since their introduction by  the United States National Weather Service (NWS) in the 1950s and are widely used  by weather forecasters in the public and private sectors. Major technical improvements  were introduced in the 1990s when the NWS, the Federal Aviation Agency (FAA), and  the U.S. 
 The reader is  advised not to be distracted by trying to understand why this function is described by the  ambiguous use of the term "ambiguity."  11.5 PULSE COMPRESSION  Pulse compression allows a radar to utilize a long pulse to achieve large radiated energy, but  simultaneously to obtain the range resolution of a short pulse. It accomplishes this by employ­ ing frequency or phase modulation to widen the signal bandwidth. (Amplitude modulation is  'also possible, but is seldom used.) The received signal is processed in a matched filter that . 
 DELAY CANCELER TRACKING THE SECONDARY SPECTRA 4HE PERFORMANCE OF THE PRIMARY SYSTEM VARIES FROM THAT OF A TRIPLE CANCELER TO A LEVEL LESS THAN THAT OF A DOUBLE CANCELER 4HE SECONDARY 
 The use of an effective earth's radius implies that dn/dh is constant with height, or in other  words, that n decreases linearly with height. This assumption is in disagrezmcnt wit11 tlre  experimentally observed refractive-index structure of the atmosphere at heights above 1 km.'  The variation of refractivity with altitude is found to be described more nearly by an exponzn-  tial function of height rather than the linear variation assumed by the 4 earth model or any  model of constant effective earth's radius. A more appropriate refractivity model is one in  which the refractivity varies exponentially with height,' 2*17  where N, = refractivity at surface of earth  h = altitude of target  h, = altitude of radar. 
 Use ismade ofthetiltaxis oftheantenna totheend that theantenna is automatically directed toward thehorizon, ortowhatever angle above or below thehorizon isdesired. The line ofsight isthereby stabilized. 9.17. 
 2.6 and  Ref. 65).  Analog delay lines that have been used in such devices include acoustic lines, lumped-  parameter delay lines, electrostatic storage tubes, and magnetic drums or disks. 
 Insuch cases, the corresponding changes have tobeincluded inthemodulator oftheradar set, with appropriate controlling switches. The above listofradar design features needed forbest useofbeacons appears somewhat formidable, and soitiswhen one istrying topatch upanantique radar setthat does no~ have such features included inits original design. When starting afresh, however, thelistdoes notinvolve unreasonable additional complications. 
 Thus, if the antenna pat- tern in the along-track direction is G = G(P), with p the angle off the beam cen- ter, we can express 3 in terms of the doppler frequency fd as P=/dX/2v and the spectrum is^.^m 2(4Ti)3/?3 L2vJ where rx is the horizontal resolution in the range direction. Of course, the half- power beamwidth may be used as an approximation, resulting in the bandwidth given by Eq. (12.13). 
 L-, S-, and X-band were also considered. 324. Sensors 2019 ,19, 1529   (a) (b)  Figure 15. 
 The ordinate labeled “response” represents the single-pulse signal-to-noise output  of the MTI receiver relative to the signal-to-noise response of a normal linear receiver  for the same target. Thus, all the response curves are normalized with respect to the  noise power gain for the given canceler configuration. The intersection at the ordinate  represents the negative decibel value of I, the MTI improvement factor for a point  clutter target processed in a linear system.FIGURE 2.35  Two-delay canceler ch02.indd   36 12/20/07   1:44:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 (/2):/. 2!$!2   Óä°Ç  * - (EADRICK  " 4 2OOT  AND * & 4HOMASON  h2!$!2# MODEL COMPARISONS WITH !MCHITKA  RADAR DATA v 2ADIO 3CIENCE  VOL   PP n  -AYn*UNE   h.EW WIND MODEL v (7-   HTTPNSSDCFTPGSFCNASAGOVMODELSATMOSPHERICHWMHWMTXT  * ! 3ECAN  2 - "USSEY  % * &REMOUW  AND 3A "ASU  h!N IMPROVED MODEL OF EQUATORIAL  SCINTILLATION v 2ADIO 3CIENCE    n    ! 6 'UREVICH   .ONLINEAR 0HENOMENA IN THE )ONOSPHERE  .EW 9ORK 3PRINGER 
 Suchsignalprocessing includes matched llitering, doppler(MTI) fillering. polarilatioll liltering, andadaptive videothresholding, F\'ellifallunwanted detections areeliminated, therearctwoadditional problems that cankadtoaproliferation ofdetections alldplaceahmdenonthecomputer: (I)multiple detections ofnewtargclsand(2)redetections ofoldtargets.Ifthesearcnotrecognized assuch, thecomputer willattempt tocorrelate themwithexisting tracksandinitiatenewtracks,which cantieupthecomputer capacity needlessly. Multiple detections ofthesametargetcanoccur inadjacent beampositions iftheechosignalisofmorethanmarginal strength.Ifthebeam scansaulliform pattern, asitwouldifitweregenerated byaconventional mechanically scanned antenna, extraneous hitsfromadjacent beampositions canbereadilyrecognized as such.Alloperator viewing aPPlwouldhavenoproblem. 
 PHASE CORRECTION FOR SCAN 
 SINK 4HESE ARE NOT ALWAYS PRACTICAL SOLUTIONS AND ONE FINDS THAT THE LAYOUT OF THE TRANSISTOR ITSELF IS OFTEN OPTIMIZED FOR A PARTICULAR PULSE WIDTH AND DUTY CYCLE IN ORDER TO ACHIEVE THE OPTIMUM PERFORMANCE AND RELIABILITY AT THE LOWEST OPERATING TEMPERATURE 4HE ACTIVE TRANSISTOR AREA ON THE SURFACE OF THE CHIP THE CHIP IS SOMETIMES CALLED  THE DIE  IS TYPICALLY DIVIDED INTO MANAGEABLE UNITS CELLS   WHERE THE CELL SIZE IS OFTEN  OPTIMIZED FOR A PARTICULAR APPLICATION OR RANGE OF APPLICATIONS )N ADDITION TO FREQUENCY CONSIDERATIONS  PULSE WIDTH AND DUTY CYCLE OR  AS A RESULT  THE PEAK AND AVERAGE DIS 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 error-detector-output voltage. 
 C. Dobson, J. Stiles, R. 
 The line-of-sight rate is constant when mis- sile and target are on an intercept (collision) trajectory. of 10 T^ will reduce miss distance to the asymptotically achievable value. This will therefore establish minimum range capability as well as set the requirement on the terminal guidance mode of a multimode missile. 
 TIME DATA FLOW IN A .!630!352 RECEIVING STATION h 4RANSMITTER  ENERGY REFLECTED BY THE SATELLITE IS RECEIVED BY VARIOUS COLLINEAR ARRAYS OF DIPOLES AT  THE RECEIVER STATIONx ;3IGNALS= FROM FOUR IN 
 ON ENGAGEMENT TARGETS WITH HIGH CLOSING SPEEDS THAT ARE NOT COMPETING AGAINST MAIN 
 2& FOR ,2/ HAS TWO FREQUEN 
 Theaveragenumber ofzero-crossings persecondattheoutputofanarrow-bandpass filterofrectangular shape whentheinputisasinewaveingaussian noiseis46 _ _[SIN+1+(/82/12/02)]1/2 no-2/0SIN+1 wherefo=centerfrequency offilter f8=filterbandwidth SIN=srgnal-to-noise (power) ratio(10.42). Figure 10.4 Basic configuration of a collerent detector. Input -  fo 9 40 ?  If a suitable device is used to measure ito, a target signal is said to be present if this number is  less thari a predeterniined (threshold) value and is said to be absent if the threshold is  exceeded. 
 MUM ARCHITECTURE IS HYBRID 
 POLARIZED WAVEGUIDE H ORN  IS ALSO SHOWN IN  &IGURE  4HE STRUCTURAL DESIGN OF THIS LARGE REFLECTOR WAS A SIGNIFICANT TASK DRIVEN BY THE NEED TO MAINTAIN LOW REFLECTOR SURFACE DISTORTION LESS THAN  MILS  WITH SEVERE WIND AND GRAVITY 
 However, its bandwidth during the 1950s tended to be 1 percent or less, with wider ranges being covered by mechanical tuning of the cavities; gang tuning (tuning all cavities at once in response to rotation of a single tuning knob or motor drive) is often used. Although a tradeoff between klystron gain and bandwidth was always known to be feasible, the stagger tuning of a klystron is far more complex than that of an IF strip. The overall frequency response of a klystron contains intermediate gain products as well as the total product of the individual cavity responses; certain tuning combinations produce excessive harmonic output; and broadband small-signal gain does not ensure broadband saturated gain. 
 This operation was achieved in ampli ﬁer type A3678. Scanning unit type 68 is illustrated in ﬁgure 4.10. The split waveguide feeds to the two horns are clearly seen. 
 Thus, Section 2.10 will discuss the design and performance of doppler  filter banks, and a detailed discussion of clutter maps will follow in Section 2.15.  Since the original work at Lincoln Laboratory to develop the MTD concept, a number  of MTD systems have been developed that vary in detail from the original concept.  Also, the use of clutter maps to inhibit excessive clutter residue, instead of control - ling clutter residue with intentionally restricted dynamic range, has been adopted in  newer MTI systems. 
 LIMITED  SIGNALS IS PERFORMED WITHOUT ALIASING DISTORTION  PROVIDED THAT THE SAMPLE RATE  F S  IS GREATER THAN  TWICE THE SIGNAL BANDWIDTH AND PROVIDED THE SIG 
  IS IN LEVEL FLIGHT %VEN SO  THE & 
 TERNS  ELECTRONICALLY STEERED AND SHAPED !S MIGHT BE EXPECTED  NO APPLICATIONS THEME WOULD ACCEPT DEGRADED RESOLUTION 4O SATISFY THAT DEMAND  THE RADAR DESIGN ADOPTED THREE BANDWIDTHS  SO THAT THE NOMINAL GROUND 
 The theory assumes that  a ray striking an edge excites a cone of diffracted rays, as in Figure 14.19. The half  angle of this diffraction cone  is equal to the angle between the incident ray and the  edge. Unless the point of observation lies on the diffraction cone, no value is assigned  the diffracted field. 
 THIRD  HIGHEST WAVES  PROVIDES SUCH A MEASURE )T IS DENOTED BY  (  AND IS TAKEN TO BE ABOUT  SIX TIMES THE SPECTRAL RMS AMPLITUDE SEE  EG  +INSMAN  &IG  
 As sidelobe levels are reduced and feed blockage becomes intolerable, offset feeds (Fig. 6.7c) become necessary. The feed is still at the focal point of the por- tion of the reflector used even though the focal axis no longer intersects the re- flector. 
 SPEED !$ CONVERTER IS A KEY COMPONENT IN RECEIVERS OF MODERN RADAR SYS 
   (& /6%2 
 BASED !IRBORNE 3PACEBORNE -ASS s  4YPICALLY NOT A MAJOR  DRIVER s  -AY BE A DRIVER IF  FIELD DEPLOYMENT IS  REQUIREDs  4YPICALLY NOT A  MAJOR DRIVERs  4YPICALLY A  SIGNIFICANT DRIVER s  #OULD BE A MAJOR  DRIVER DEPENDING ON SIZE OF ANTENNA AND PLATFORMs  ! MAJOR DRIVER LAUNCH  COSTS ARE VERY HIGH AND ARE DRIVEN BY AVAILABLE VOLUME AND MASS FOR RADAR PAYLOAD s  5SE OF LIGHT WEIGHT  MATERIALS IS IMPORTANT 6OLUME s  4YPICALLY NOT A MAJOR  DRIVER s  -AY BE A DRIVER IF  FIELD DEPLOYMENT IS REQUIREDs  $EPENDS  A  DRIVER IN SOME CASESs  4YPICALLY A  SIGNIFICANT DRIVER s  #OULD BE A MAJOR  DRIVER DEPENDING ON SIZE OF ANTENNA AND PLATFORMs  ! MAJOR DRIVER LAUNCH  COSTS ARE VERY HIGH AND ARE DRIVEN BY AVAILABLE VOLUME AND MASS FOR RADAR PAYLOAD s  /NCE IN SPACE    ANTENNA DEPLOYMENTS ARE TYPICALLY NEEDED  EG  UNFOLDING  ETC 4HERMAL s  #AN BE A MAJOR  DRIVER s  2ADARS ARE TYPICALLY  HIGH POWER s  (IGH POWER DENSITIES  AT FEED OR FEED ARRAY ARE COMMON s  #OOLING SYSTEM  DESIGN TO MAINTAIN FEED TEMP CAN BE A CHALLENGEs  #AN BE A MAJOR  DRIVER s  2ADARS ARE  TYPICALLY HIGH POWER s  (IGH POWER  DENSITIES AT FEED OR FEED ARRAY ARE COMMON s  #OOLING SYSTEM  DESIGN TO MAINTAIN FEED TEMP CAN BE A CHALLENGEs  #AN BE A MAJOR  DRIVER s  2ADARS ARE  TYPICALLY HIGH POWER s  (IGH POWER  DENSITIES AT FEED OR FEED ARRAY ARE COMMON s  #OOLING SYSTEM  DESIGN TO MAINTAIN FEED TEMP CAN BE A CHALLENGEs  ! MAJOR DRIVER  NEED  SOPHISTICATED MODELING TO PREDICT SOLAR HEATING THROUGHOUT ORBIT s  0ASSIVE COOLING SYSTEMS   ARE GENERALLY EMPLOYED  EG  HEAT PIPES 6IBRATION s  4YPICALLY NOT A MAJOR  DRIVER s  (OWEVER  MUST  CONSIDER VIBRATION DURING TRANSPORT TRUCK  AIRPLANE  OTHER  s  4YPICALLY NOT A  MAJOR DRIVERs  4YPICALLY A MAJOR  DRIVERs  4YPICALLY A MAJOR  DRIVER  DRIVEN BY LAUNCH VEHICLE ROCKET 4!",%  -ECHANICAL $ESIGN $RIVERS FOR 2EFLECTOR !NTENNA 3YSTEMS AS A &UNCTION OF 0LATFORM.   2%&,%#4/2 !.4%..!3   £Ó°ÎÇ MASS AND VOLUME CONSTRAINTS GENERALLY HAVE A SIGNIFICANT IMPACT ON THE REFLECTOR SYSTEM  DESIGN &URTHERMORE  SOME SORT OF STOWAGE AND DEPLOYMENT OF THE REFLECTOR IS SOME 
 The spurious-effects chart also demonstrates spurious input responses. One of the stronger of these occurs at point B, where the 2H - 2L product causes a mixer output in the IF passband with an input frequency at 0.815. All the prod- ucts of the form N(H - L) produce potentially troublesome spurious responses. 
 A doppler correlation window is set equal to  the maximum doppler offset due to linear-FM ranging from a target at the maximum  instrumented range. For doppler-only correlation, the PFA per range-doppler cell to  provide a specified false report time is  PNT m nN N Trd fmFA FM FR=        −1 2 1ln( )  1m  (4.18) where Nr = number of independent range samples processed per IPP  Nf =  number of independent doppler filters visible in the doppler passband  (number of unblanked filters/FFT weighting factor)  Td =  total dwell time of the multiple PRFs including postdetection integration  (if any), space change, and any dead time  n = number of looks in a dwell time  m =  number of detections required for a target report (for a typical HRWS  dwell, n = 3 and m = 3)  m n   = binomial coefficient = n!/[m!(n-m)!]  TFR =  false-report time (per Marcum’s definition where the probability is   0.5 that at least one false report will occur in the false-report time; this  can be related to the average time TA VG between false reports by    TFR ≈ TA VG ln(2))  NFM =  kFM,max (2Rmax/c) = number of independent doppler filters in the doppler  correlation window  kFM,max  = steepest linear-FM slope magnitude  Rmax = maximum instrumented range ch04.indd   44 12/20/07   4:53:41 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 ERALLY BE REGARDED AS BEING IN MOTION COMPARED WITH THE CLUTTER  IN THE '02 CASE  THE TARGET AND THE CLUTTER ARE SPATIALLY FIXED AND THE RADAR ANTENNA IS MOVED WITH RESPECT TO THE ENVIRONMENT )T IS ASSUMED THAT  DATA ARE RECORDED TO  AN ADEQUATE RESOLUTION  -OST ANTENNAS USED  IN SURFACE PENETRATING APPLICATIONS HAVE A LIMITED LOW 
 Reception of digital multi-beamforming. 2.2. Signal Model As shown in Figure 3, the speed of the carrier is vand the wavelength is λ. 
 This signal, received back atthe radar, provides an artificial echo which can beutilized invarious ways (Chap. 8). Here theanalogue ofthe radar equation forradar-beacon operation will be discussed. 
 Therefore, Δσis deﬁned as the maximum NRCS contrast, or in other words, it is calculated from the brightest or darkest part of the eddy spiral to represent its visibility from the simulated image. The larger the value of Δσ, the clearer the spirals. To avoid the bias that may result from speckles or thermal noises, an average NRCS of twenty pixels was used for each along or beside the spiral to calculate the difference. 
 642–647. 14. Zhang, Y.; Wu, T. 
 After detection and cancellation ofthe echoes inthe delayed and undelayed channels, theresidual video signal must beamplified, rectified, and limited forapplication toanintensity-modulated indicator such as. SEC. 16.20] DELAY-LINE TRIGGER CIRCUITS 675 aPPI. 
 Figures 12.3 and 12.4 show the effect of moisture content on prop- erties of plants and of soil. The high permittivity of plants with much moisture means that radar return from crops varies as the plants mature, even when growth is neglected. VOLUMETRIC MOISTURE mv FIG. 
 AREPS may be freely obtained at http://areps   .spawar.navy.mil.  2. W. 
 Aninteresting technique forgraphically portraying thevariation ofthebeamshapewith scananglehasbeendescribed byVonAulock, 15anexample ofwhichisshowninFig.8.3.The antenna radiation patternisplottedinspherical coordinates asafunction ofthetwodirection cosines,cosaxandcosa}.,oftheradiusvectorspecifying thepointofobservation. Theangle4> ismeasured fromthecosaxaxis,and0ismeasured fromtheaxisperpendicular tothecosax a:1dcosayaxes.InFig.8.3,4>istakentobeaconstant valueof900andthebeamisscanned in Figure8.3Beamwidth andeccentricity ofthescanned beam.(FromVonAuJock1S,Courtesy Proc.IRE.). tltc 0 coorililt;t~c. 
 SCAN SAMPLE TIME SERIES #OURTESY )%%           
 -Èqn ! SOLID 
 Acompromise between theisolated (l2-dBslope)andextended (6-dBslope)targetechoesmightbea characteristic withaslopeof9dB/octave. Theconstant outputproduced byshaping the doppler-amplifier frequency-response characteristic isnotonlyhelpfulinlowering thedy­ namicrangerequirements ofthefrequency-measuring device,buttheattenuation ofthelow frequencies efTectsareduction oflow-frequency interfering noise.Lowered gainatlowalti­ tudesalsohelpstoreduceinterference fromunwanted rellections. Theresponse attheupper endofthefrequency characteristic israpidlyreduced forfrequencies beyondthatcorrespond­ ingtomaximum range.Ifthereisaminimum targetrange,theresponse isalsocutofTatthe low-frequency end,tofurtherreducetheextraneous noiseentering thereceiver. 
 ING LONG 
 MENTALLY MEASURED SINGLE 
 Gunn and G. D. Kinzer, “The terminal velocity of fall for water droplets in stagnant Air,”   J. 
 16.50  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 are present, the target is said to be partially polarized; when no random component is  present, the target is fully polarized. Radar signals are frequently only partially polarized,  especially where multiple bounces occur within the target area. For the nonrandom part, we must define a Stokes vector using an ensemble average  of each component; the averaging may be over time or look angle. 
 VIDE THE INPUT AND OUTPUT CONNECTIONS AS NEEDED FOR AN AMPLIFIER #&!S MIGHT HAVE AN EFFICIENCY FROM  TO   USE A LOWER VOLTAGE THAN LINEAR 
 ING  LOADING  FILTERING  AND SWITCHING FUNCTIONS THAT ARE NECESSARY FOR MULTISTAGE 42 MODULE DESIGNS 5NLIKE THE SILICON POWER TRANSISTORS  THE 'A!S &%4 AND ITS ASSOCIATED  &)'52%  4YPICAL TRANSISTOR CURRENT 
 Each of the switchable circulators connects either directly across (counterclockwise)  or via the short-circuited length. Isolation in excess of 30 dB is required. It is clear  that the insertion loss of time-delay circuits is very high for most practical systems. 
 GENCE %,).4  DEVICES  COLLATING THE INFORMATION IN SUPPORT DATABASES THAT ARE THEN USED TO INTERPRET %- EMISSION DATA  TO UNDERSTAND THE RADAR SYSTEM FUNCTIONS  AND TO PROGRAM REACTIONS AGAINST THE RADAR %7 IS ORGANIZED INTO TWO MAJOR CATEGORIES ELECTRONIC WARFARE SUPPORT MEASURES %3-  AND %#- "ASICALLY  THE %7 COMMUNITY TAKES AS ITS JOB THE DEGRADATION OF RADAR CAPABILITY 4HE RADAR COMMUNITY TAKES AS ITS JOB THE SUCCESSFUL APPLICATION OF RADAR IN SPITE OF WHAT THE %7 COMMUNITY DOES THE GOAL IS PURSUED BY MEANS OF %##- TECHNIQUES 4HE DEFINITIONS OF %3-  %#-  AND %##- ARE LISTED BELOW   o %3- IS THAT DIVISION OF %7 INVOLVING ACTIONS TAKEN TO SEARCH FOR  INTERCEPT  LOCATE   RECORD  AND ANALYZE RADIATED %- ENERGY FOR THE PURPOSE OF EXPLOITING SUCH RADIATIONS IN THE SUPPORT OF MILITARY OPERATIONS 4HUS  %3- PROVIDES A SOURCE OF %7 INFORMATION REQUIRED TO CONDUCT %#-  THREAT DETECTION  WARNING  AND AVOIDANCE %#- IS THAT DIVI 
 199-201, April, 1959.  514INTRODUCTION TORADAR SYSTEMS 54.Bush.T.F.,F.T.Ulaby,andW.H.Peake:Variability intheMeasurement ofRadarBackscatter. IEEETrans.,vol.AP-24,pp.896-899. 
 Bristol, T. W.: Acoustic Surface-Wave-Device Applications, Microwave J., vol. 17, pp. 
 Design Procedure. —Having blocked out aproposed system, wemay now sketch the design procedure that fixed the various apparatus con- stants and dimensions. Design commenced with the choice ofanindicator. 
 221-225.  83. White, W. 
 The detection of landfall is extremely helpful, but because of the presence ofstrong coastal echoes, coastal shipping reconnaissance presents great dif ﬁ- culties. The radius of search ahead and laterally is extended to a distance dependent on the size and aspect of the surface vessel. Convoy escort : ASV has enabled contact to be made with convoys at night and in extremely poor visibility. 
 LAR TO RANDOM SEQUENCES AND  THEREFORE  POSSESS DESIRABLE AUTOCORRELATION FUNCTIONS 4HEY ARE OFTEN CALLED  PSEUDORANDOM NOISE 02.   SEQUENCES (ISTORICALLY  THESE  SEQUENCES WERE GENERATED USING  N STAGES OF SHIFT REGISTERS WITH SELECTED OUTPUT TAPS  USED FOR FEEDBACK SEE &IGURE   7HEN THE FEEDBACK CONNECTIONS ARE PROPERLY CHOSEN  THE OUTPUT IS A SEQUENCE OF MAXIMAL LENGTH  WHICH IS THE MAXIMUM LENGTH OF A SEQUENCE OF S AND S THAT CAN BE FORMED BEFORE THE SEQUENCE IS REPEATED 4HE LENGTH OF THE MAXIMAL SEQUENCE IS  .    N  
 Thefour beamsaredisplaced symmetrically'at anoutward angleof25°fromthevertical.Thebeamsare timesharedbyasinglechannel whichisswitched through thefour-beam sequence every. CW AND FREQUENCY-MODULATED RADAR %  250 Ins. A phase-monopulse tecltrlique is ilsed to reduce the terrain bias effect.68 The unit  weighs 44 poi~rids including radorne, and requires 165 VA of power. 
 DL Sciences, Inc. Carlo Kopp Monash University 5.1 INTRODUCTION In spite of more than a half century of improvements in radar performance and  reliability, the effort required for deployment, operation, and maintenance of most  radars is substantial. Furthermore, the power-aperture product is never as large as  desired. 
 BEAM SCANNING ANTENNAS ARE  USED BY BOTH TRANSMITTER AND RECEIVER IN A BISTATIC SURVEILLANCE RADAR  INEFFICIENT USE IS MADE OF THE RADAR ENERGY BECAUSE ONLY THE VOLUME COMMON TO BOTH BEAMS CAN BE OBSERVED BY THE RECEIVER AT ANY GIVEN TIME /UTSIDE THIS COMMON BEAM VOLUME  TARGETS ARE LOST TO THE RECEIVER &IGURE  SHOWS THE GEOMETRY 4HIS PROBLEM COMMONLY ARISES WHEN ATTEMPTING TO HITCHHIKE OFF MONOSTATIC SURVEILLANCE RADARS &OUR REMEDIES ARE AVAILABLE TO MITIGATE THE BEAM SCAN 
 SEC. 1.3] COMPONENTS OFARADAR L9YSTEM 7 firing ofthemodulator. This sends ahigh-power, high-voltage pulse to themagnetron, which isthetype oftransmitting tube almost universally used inmodern radar. 
 ATTENUATION CROSS SECTION DEPENDS ON THE TEMPERATURE BECAUSE OF  ITS EFFECTS ON THE DIELECTRIC PROPERTIES OF WATER   IT IS IMPORTANT TO EVALUATE THE ATTENU 
 Antennas mounted onaircraftmustalsobehousedwithinaradome toofferprotection fromlargeaerodynamic loadsandtoavoiddisturbance tothecontrolofthe aircraftandminimize drag. Thedesignofradomes forantennas maybedivided intotwoseparate andrelatively distinct classes,depending uponwhether theantenna isforairborne orground-based (or ship-based) application. Theairborne raoome ischaracterized bysmallersizethanground­ basedradomes sincetheantennas thatcanbecarriedinanaircraftaregenerally smaller. 
 ON INCIDENCE 4HEORETICAL PREDICTIONS IN THE END 
 (23.20), r is the distance from the center of the cell of radius r0, and C1 and C2 are positive constants. Attenuation by Hail. Ryde23 concluded that the attenuation caused by hail is one-hundredth of that caused by rain, that ice-crystal clouds cause no sensible attenuation, and that snow produces very small attenuation even at the excessive rate of fall of 5 in/h. 
 DUSK ORBIT WAS CHOSEN TO MAXIMIZE ILLUMINATION OF THE SOLAR PANELS  WHICH ALLOWS  MINUTES OF 3!2 OPERATION PER ORBIT 2!$!23!4 
 45/26, 13th July 1945 (TNA AIR 65/185)Airborne Maritime Surveillance Radar, Volume 1 4-33. IOP Concise Physics Airborne Maritime Surveillance Radar, Volume 1 British ASV radars in WWII 1939–1945 Simon Watts Chapter 5 ASV Mk VII 5.1 Development of ASV Mk. VII The original H 2S Mks I and II operated at a wavelength of 9 cm. 
 4(% 
 POWER PHASE SHIFT CONTROL FOR ELECTRONIC STEERING FOLLOWED BY POWER AMPLIFICATION IN EACH OF  CHANNELS 4HESE ARE CONNECTED TO THE  ELEMENTS OF THE PHASED ARRAY THROUGH AN  
 The two-frequency CW radar spectrum (and its corre­ sponding waveform) are not always suitable in practice since they lead to ambiguous measure­ ments ir the frequency separation 8 between the two sine waves is greater than c/2R,,. where c  is the velocity of propagation and R,, is the maximum unambiguous range. If the range  neasurement is to be unambiguous, the spectrum must be continuous over the bandwidth B. 
 DETECTED AND COMPARED WITH A SUITABLE THRESH 
 149–154. 191. J. 
 TERS HAVE BEEN FROM A SMALL FRACTION OF A WATT TO THE ORDER OF A MEGAWATT 4YPES OF 2ADAR 4RANSMITTERS  4HE VERY FIRST hRADARS v SUCH AS THOSE USED BY  (EINRICH (ERTZ THE FIRST RADAR SCIENTIST  IN THE LATE S AND THE SHIPBOARD RADAR INVENTED BY #HRISTIAN (ULSMEYER THE FIRST RADAR ENGINEER  IN THE EARLY S USED THE SPARK GAP AS THE TRANSMITTER )T WAS A VERY POOR TRANSMITTER  BUT THAT IS NOT UNUSUAL IN THE  EARLY DAYS OF A NEW AND DIFFERENT DEVELOPMENT 4HE $E&OREST  GRID 
  
 155.  42. Barton. 
   PP n    $ . (ELD  h4HE .!3!*0, MULTIPOLARIZATION 3!2 AIRCRAFT PROGRAM v  $IG )'!233    PP n    $ , %VANS ET AL  h2ADAR POLARIMETRY ANALYSIS TOOLS AND APPLICATIONS v  )%%% 4RANS 'EOSC   2EM 3ENS  VOL   PP n    (OOGEBOOM ET AL  h4HE 0(!253 0ROJECT  2ESULTS OF THE $EFINITION 3TUDY INCLUDING THE 3!2  4ESTBED 0(!23 v )%%%  4RANS ON 'EOSC AND 2EMOTE 3ENSING  VOL   PP n    9 
 DOPPLER CELLS  AROUND EACH OF THESE MEASUREMENTS IN ORDER TO ASSOCIATE DETECTIONS WITH EXISTING TRACKS 4HE TRACKER  USUALLY IMPLEMENTED WITH A NINE 
 Note that for crfT « 1 the average SCR improvement is due only to the coherent integration of all the pulses in the CPI. The implementation of a single MTI filter will result in a performance be- low that shown in Fig. 15.19. 
 This occurred in January, 1938.  Although the power delivered to the antenna was only 6 kW, a range of 50 miles-the limit of  the sweep-was obtained by February. The XAF was tested aboard the battleship New York,  in maneuvers held during January and February of 1939, and met with considerable success. 
 15.12. (One of the curves showing the effect of feedback on the triple canceler is not straight because two of the three zeros are not at the origin but have been moved along the unit circle the optimum amount for 14 hits per beam width. Thus, at 40 hits per beamwidth, these two zeros are too far removed from the origin to be very effective.) In theory, it is possible to synthesize almost any velocity response curve with digital filters.16 For each pair of poles and pair of zeros on the Z plane, two delay sections are required. 
 POWER AMPLIFIERS IN ORDER TO DEVELOP THE REQUIRED RADIATED LEVELS 4RANSISTOR FINGERS ARE COMBINED INTO --)# AMPLIFI 
 Equation (2.29) may be converted to power by replacing the  signal - to -rrns-noise-voltage ratio with the following:  .I signal amplitude fi(rms signal voltage) .-.- - - - = (2 signal power) 'I2 = (:) - '12  d,:,I2 - rrns noise voltage rms noise voltage noise power  We shall also replace If;/2rC/, by In (l/P,,) [from Eq. (2.24)). Using the above relationships,  the probability of detection is plotted in Fig. 
 /1:.f.f /1)75  lmer11atio11al Radar C01!f"em1ce, Apr. 21-23, 1975, Arlington, Va, pp. 210 214, IEEE Publication 75  CHO 938-1 AES. 
 MITTER 
 V . N. Bringi, T. 
 169. R. L. 
 The Germans deployed several different types of radars during World War 11. Ground-  based radars were avgilable for air search and height finding so as to perform ground control  of intercept (GCI). Coastal, shipboard, and airborne radar were also employed successfully in  significant numbers. 
 TIONAL PROCESSING CORRECTIONS CAN STILL USUALLY RESULT IN AN ESSENTIALLY UNDISTORTED GROUND IMAGE -OTION #OMPENSATION  4HE BASIC THEORY OF 3!2 RELIES ON THE ASSUMPTION THAT  THE PLATFORM  AND THEREFORE THE 3!2 ANTENNA  IS TRAVELING ALONG A STRAIGHT 
 Still another advantage of the Cassegrain antenna is the flexibility with which diNerent  trarismitte~s and receivers can be substituted because of-the availability of the antenna feed  system at the back of the reflector rather than out front at the normal focus. The Haystack  microwave research system,24 for example, is a fully steerable Cassegrain antenna 120 ft in  diameter, enclosed by a 150-ft diameter metal space-frame randome. It was designed to oper-  ate at frequepcies from 2 to 10 GHz for radar, radio astronomy, and space communications. 
  
 Biased Diodes. —Figure 13.21 illustrates two self-evident methods of limiting theexcursion ~fasignal byclipping offthetop atalevel deter- mined byad-cpotential difference applied tothe circuit. The circuit ofFig. 
 Medhi~rst, arid S. 1). Pool: Superdirectivity, Proc. 
 HORIZON RADAR v IN  $EFENCE !PPLICATIONS OF 3IGNAL 0ROCESSING  $ ! #OCHRAN  " -ORAN  AND  , 7HITE EDS   !MSTERDAM %LSEVIER    PP n  9 "AR 
 William H. Long  joined the authors for the second edition (1990). John P. 
 A small aircraft, nose- on view, with a single engine and no significant reflectors attached to the wings will  have a sang of approximately 0.1 L, whereas larger aircraft with an outboard engine and  possibly wing tanks will have a sang approaching the value of 0.2 L. The aircraft side  view also tends toward the value of 0.2 L because of a more continuous distribution  of reflecting areas. Estimation of angle scintillation rms error in units of target span  can be made by relating the approximate target distribution in Figure 9.21 with actual  aircraft configurations. 
 Therefore, we assume that the DEM data of Rge(j) are also Hne. 7. According to Rge(j) and Hne, the slant range corresponding to Rge(j) can be calculated: Rnew=⎭radicalBig R2ge(j)+H2ne (30) 8. 
 WAVE #&! IS ALSO KNOWN AS THE !MPLITRON )T IS POSSIBLE TO PULSE SOME #&!S  WHICH HAVE COLD CATHODES  TO EMPLOY WHAT IS  CALLED $# OPERATION  WHERE THE TRANSMITTER IS TURNED ON AND OFF TO GENERATE A PULSE  WAVEFORM WITHOUT THE NEED FOR A HIGH 
 The width of the ECM pulse is normally wider than the radar skin return.13 This type  of deception can be counteracted by an ECCM technique such as the cover-pulse  channel, where the tracking is on the ECM transmission rather than on the skin  return from the target.29 The digital coherent implementation of the Dicke-Fix receiver concept requires the  use of a coherent hard limiter that preserves the phase of the signal while keeping the  amplitude at a constant value.‡ The coherent limiter is inserted upstream of the pulse  compression filter in a radar that uses phase-coded signals. In reception, the jammer  and target signals are cut in amplitude. The preservation of the target signal phase  coding allows the integration of target energy by means of the pulse compression  filter matched to the phase code. 
 Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 17 .18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 is often called multiplicative noise  (not really noise in the strict sense), which is pro - portional to the average scene intensity. Carrara et al.3 define multiplicative noise as follows: “The principal contributors to  multiplicative noise are the integrated sidelobes of the system impulse response, the  energy present in the scene as a result of range and azimuth ambiguities, and digital  [i.e., from quantization in the analog-to-digital converter] noise” (p. 
 Amore subtle siting requirement istheavoidance ofground “clutter”; permanent echoes arebothersome atcertain sites, particularly iftheradar targets frequently pass atnearly thesame range and direction assuch echoes. Moving-target indication, dkcussed inChap. 16,isnow practicable toalleviate ground clutter. 
 However, dual reflector systems (e.g., Cassegrain) have an  additional degree of freedom and surface shaping can be applied to decrease the taper  loss and enable aperture efficiencies in excess of 70%.25,26 A different type of dual reflector system that is particularly well-suited to applica - tions where limited electronic scanning is required is the so-called confocal reflector  system27–30 shown in Figure 12.24. This system employs two parabolic reflectors, a  main and a sub, that share a common focal point. The optics of this system is designed  such that a plane wave source, say from an array, is first converted to a spherical  wave at the subreflector. 
 Standard deviation of  acceleration change is sa.46,47σak k k kT T T T24 3 3 22 2/ /β αα = − − −2 2 4 1( )and γσσtrack=a mT2 4 2Vary sa to increase/   decrease gains  and obtain desired  performance using  equations in Table 7.3.Responds very well to  maneuvers, but operates at  the edge of filter stability.  Higher radar measurement  rate can actually result in less  accurate track.48 Model no. 3: Random  change in velocity at each  measurement interval.49σv20 0 0 1βαα=−2 2 ( ) and γσσtrack=v mT2 2 2Vary sv to increase/   decrease gains  and obtain desired  performance using  equations in Table 7.3.Very conservative with  respect to filter stability.TABLE 7.4  Comparison of Methods of Tuning Kalman Filter for Practic al Radar Tracking Problems ch07.indd   31 12/17/07   2:14:25 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Future trends appear tolead toward higher frequencies, uptoand including microwaves. Comparatively speaking, theuse ofsuch frequencies ischaracterized bythe possibility ofusing simple, highly directional antennas, bylow gain inomnidirectional antennas, byreduction inman-made static (except forpulse interference from radars), byagreat increase inthe overwater diffraction effect, byalarge number ofavailable channels, and bytherelatively low power now available forc-w operation. The powers available forcontinuous operation with equipment devel- oped bytheend ofthewar areapproximately asfollows: 100 Me/see (FM)., ........ 
 The red bulb in-  dicates flight below and amber above that altitude.  American practice reverses the green and amber. It is  obviously not impossible to link such a device with an  automatic pilot, enabling the aircraft to be flown hands-  off at a predetermined height within the range limit of  the altimeter. 
 2 was the average value of the power over the duration of a pulse of  sine wave. The ratio RI is twice the average signt:11-to-noise power ratio when the input signal  s(t) is a rectangular sine-wave pulse.] The output voltage of a filter with frequency-response  function H(J) is  !s0(t) I = If:  00 S(J)H(J) exp (j2nft) df I ( 10.8)  where S(J) is the Fourier transform of the input (received) signal. The mean output noise  power is  ( 10.9)  where NO is the input noise power per unit bandwidth. 
 BASED  8 
 3 $ATA ,INK  THROUGH THE RADAR PRIMARILY FOR MAP IMAGERY "ECAUSE THERE MAY BE THOUSANDS OF WAVELENGTHS AND A GAIN OF MILLIONS THROUGH A RADAR  AUTOMATIC GAIN CONTROL AND CALIBRATION !'##!,  IS USUALLY REQUIRED FAIRLY OFTEN -ODES OPTIMIZED FOR THIS FUNCTION ARE INVOKED THROUGHOUT A MISSION 7AVEFORM 6ARIATIONS BY -ODE  !LTHOUGH THE SPECIFIC WAVEFORM IS HARD TO PRE 
 Thefirstechoesat200MHzwere received July22,1936,lessthanthreemonthsafter thestartoftheproject.Thisradarwasalso thefirsttoemployaduplexing systemwithacommon antenna forbothtransmitting and receiving. Therangewasonly10to12miles.Inthespringof1937itwasinstalled andtestedon thedestroyer Leary.Therangeofthe200-MHz radarwaslimitedbythetransmitter. The development ofhigher-powered tubesbytheEitel-McCullough Corporation allowed an improved designofthe200-MHz radarknownasXAF.Thisoccurred inJanuary, 1938. 
 The antenna was assumed to "searchlight" the target. Statistical aspects of signal detection were not considered. D. 
 Some of the characteristics, capabilities, and limitations of the bislatic radar will be  described in this section and compared with the more usual monostatic radar.  Any radar which employs separate antennas for transmitting and receiving might he  called bistatic, but for purposes of this discussion a bistatic radar is assumed to be one in which  the separation between transmitter and receiver is comparable with the target distance. For  aircraft targets, the separations might be of the order of a few miles to as much as several  hundred miles. 
 68. R. F. 
 The generation by digital processing of N filters from the outputs of N taps of a transver­ sal filter requires a total of (N -l )2 multiplications. The process is equivalent to the computa- 1 io11 or a disnl'tl' Fo11ri1•r trc111sfiJ1m. 1 lowcver, when N is some power of 2, that is, N = 2, 4, 8,  16 ..... 
 Z COORDINATE SYSTEM CENTERED AT THE RECEIVE SITE  WHERE  Z IS CO 
 For an array with four thousand elements, a  three-hit pliase shifter will give rriis sitieiobes better ttian 47 dB below the main beani, and a  four-bit phase sllifter gives 53 dl3 sidelobes. Thus three or four bits sllould be sufficie~lt for  tilost large arrays. except where very low sidelobes are desired. 
 The beams are stationary in space  and overlap at approximately the 4 dB points. This is in contrast to the previously  discussed methods of scanning, where the beam can be steered accurately to any posi - tion. The beams all lie in one plane. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.52  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 At present, the most powerful tools for dealing with additive interference, as well  as some classes of spread-doppler clutter, are the techniques of adaptive processing. 
 F. Vetelino, T. J. 
 (A lens has the property that a Four~er transform  relation exists between the amplitude distribution of the illumination at the front and back  focal  plane^.^)  With the conical and cylindrical lens. inserted, the image is erect and is simultaneously  focused in the range and cross-range dimensions, but it lies at infinity. To bring the image to  some conveniently located plane, a spherical lens is inserted. 
 QUENCY IN RANGE 4HIS IS POSSIBLE IF THE FREQUENCY OFFSET IS IMPLEMENTED ON RECEIVE BUT NOT ON TRANSMIT  !T ANY PARTICULAR RANGE  THE FILTER NOTCH IS EFFECTIVELY AT ONE FREQUENCY AND THE CENTER FREQUENCY OF THE CLUTTER SPECTRUM AT ANOTHER 4HE DIFFERENCE BETWEEN THESE FREQUENCIES RESULTS IN A DOPPLER 
 %23 
 Space object  identification (SOI) radars are an example of those that extract target shape information. The  synthetic aperture radar (SAR) which maps the terrain is another example. Radars that  determine the shape of a target are sometimes called inlugirtg radars. 
 In a high-PRF radar, the range foldover may leave little clear region in the range dimension, thus degrading target detectability. By using a lower or medium PRF, the clear region in range is increased at the ex- pense of velocity foldover for high-doppler targets that are in the clutter-free re- gion in high PRF. For example, Fig. 
 /, !N AIRBORNE SEARCH 
 The rate of charge of condenser C depends upon  the capacity of this component and the current flowing  through Va. In the Cossor oscillograph time-base  advantage is taken of both these factors, rough control  being effected by the selection of a number of fixed  condensers on a rotary switch, while a progressive  adjustment is provided in the form of a ‘velocity’ con-  trol varying the screen volts on the pentode charging  valve.  This three-valve time-base circuit is typical of many  used in radar practice, but there is one simple circuit  giving a useful saw-tooth wave-form and employing  only one valve. 
 CLUTTER RATIO IMPROVEMENT WILL BE USED #LUTTER !TTENUATION  4HE )%%% DEFINITION READS CLUTTER ATTENUATION #!   )N MOVING 
 CIES  BUT THEY ARE CAPABLE UP TO FREQUENCIES APPROACHING  '(Z 'RID 
 ORDER INTERMODULATION 4HE AVAILABLE SPURIOUS 
 This would have increased theantenna gain and also reduced the size of the clutter patch illuminated by a pulse. The pulse length and pulse repletion frequency seem to have been unchanged from ASV Mk. VI. 
 COOLED FOR NORMAL OPERATION  BUT AN EMERGENCY BACKUP FORCED 
   
 89.Gamhle. W.L..andT.D.Hodgens: Propagation ofMillimeter andSubmillimeter Waves.U.s.Army MissileResearch ollClDC!'elopmellt Command, Tech.Rept.TE-77-14. June.1977. 
 CESSING v IN TH %UROPEAN 2ADAR #ONF  "ARCELONA    PP n   % ! 2OBINSON  h0REDICTIVE DECOMPOSITION OF TIME SERIES W ITH APPLICATION TO SEISMIC EXPLORA 
 $/7  8 
 K-scope. A modified A-scope in which a target appears as a pair of vertical deflections. When the radar  antenna is correctly pointed at the target, the two deflections are of equal height, and when not so  pointed, the difference in deflection amplitude is an indication of the direction and magnitude of the  pointing error. 
 When the array is scanned, the influence of elements several wavelengths  distant is also significant. For dipoles above a ground plane, the magnitude of the  coupling between elements decays rapidly with distance. For a reasonable indication  of array performance, an element in the center of a 5-by-5 array may be taken as  typical of an element in a large array. 
 In this example, the wind speeds are high so the sea will be rough, but it was noted  above that the SPM approximation used in Figure 15.19 requires waveheights much  less than a centimeter, so this approximation is totally invalid for these data. Moreover,  the Phillips spectrum was used as the sea surface spectrum, but there is no evidence  that this spectrum holds down to the required capillary wavelength of about 1.5 cm.  In fact, the nature of the sea spectrum in this range remains uncertain and has been  referred to as “one of the most exciting unsolved problems of the sea surface.”16 The  primary effect of the two-scale model  is simply to raise the inapplicable SPM values  for H-polarization, which are dropping sharply with grazing angle, by including higher  local angles via Eq. 
 The above description of the cell-averaging CF AR assumed that the background from  which the threshold was set was determined by sampling in range. In those radars which  extract the doppler frequency shirt, as with a bank of doppler filters, the estimate of the  background tan be based on both the range and the doppler domains. 77 It is also possible to  utilize data from the adjacent angle-resolution cells to establish the threshold. 
 188- 207,  March, 1965.  105. Larrench, W.: A Homogeneous, Rigid, Ground Radome, Proc. 
 DETECTION MERGING ALGORITHM  WHICH DECIDES  WHETHER A NEW DETECTION IS ADJACENT TO ANY OF THE PREVIOUSLY DETERMINED SETS OF ADJACENT DETECTIONS )F THE NEW DETECTION IS ADJACENT TO ANY DETECTION IN THE SET OF ADJACENT DETEC 
 Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 11.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 ● Class-C-biased amplifiers are very sensitive to any deviations from the nominal  operating point. Class-C-biased amplifiers exhibit sensitivity to RF drive level and  load impedance that may degrade the output pulse characteristics. 
 Coherent radar performance is even more affected by spurious mixer characteris - tics. Range and velocity accuracy is degraded in pulse doppler radars; stationary target  cancellation is impaired in MTI (moving-target indication) radars; and range sidelobes  are raised in high-resolution pulse compression systems. Spurious Distortion of Radiated Spectrum. 
 18, pp. 50–60, 1967. 57. 
 1970. 79.KroslC7ynsky. 1.:Efficiency oftheTwo-Frequency MTISystem.TireRadioalldElectronic Engineer. 
 The entropies are getting smaller and IC values larger with iteration, showing that the quality of the image is improved. The entropies and IC values of ship04 are changing greatly, demonstrating that the image quality of ship04 sub-image processing with the proposed method is good. The geometrical features of ship03 and ship04 are shown in Figure 14. 
 The Wave Spectrum.  The ocean wave spectrum  describing the sea surface  appears in several forms. If the time history of the surface elevation is monitored at a  fixed point, the resulting time series may be processed to provide a frequency spectrum   S(  f  ) of the surface elevation, where S(  f  )df is a measure of the energy  (i.e., square  of the waveheight) of the waves in the frequency interval between f and f + df. 
 Benjamin, R.: Man and Machine in the Extraction and Use of Radar Information. J. Brit. 
 For control of  air traffic en route from one terminal to another, long-range Air Route Surveillance  Radars (ARSR) are found worldwide. The Air Traffic Control Radar Beacon System  (ATCRBS) is not a radar but is a cooperative system used to identify aircraft in flight. It  uses radar-like technology and was originally based on the military IFF (Identification  Friend or Foe) system. 
 Target glint is the angular displacement in apparent phase center of a target  return and is caused by the phase interference between two or more dominant scatters  within a radar resolution cell. As the target aspect angle changes, this phase interfer - ence changes, shifting the apparent phase center, often with excursions beyond the  physical extent of the target. These excursions can significantly increase the errors in  angle tracking or measurement systems. 
  
 Berkowitz (ed.), New York, NY: John Wiley and Sons, 1966. 42. J. 
 211, inthe region where. SEC. 2.12] PROPAGATIO.Y OVER.4REFLECTING SURFACE 51 (30) For this case thesine inEq. 
  
 A sphere of radius fl will roll off 3 dB at (TT - P) = X/ra/, whena/X > I.15 Although the fl/X > 1 criterion is not satisfied in Fig. 25.7, the curve for a = 3.2X still exhibits this phenomenon: 3 dB reduction in <JF at p = 174°. (The value of o> at p = 180° also matches 4i&42/X2 within 1 dB.) Figure 25.7 shows the rolloff approximating JQ(x)/x down to p - 130°, where J0 is a Bessel function of zero order. 
 TIONS v )NT * 2EMOTE 3ENSING  VOL   PP n    0 2OSEN  3 (ENSLEY  ) *OUGHIN  & ,I  3 -ADSEN  % 2ODRIGUEZ  AND 2 'OLDSTEIN  h3YNTHETIC  APERTURE RADAR INTERFEROMETRY v 0R OC )%%%  VOL   PP n    2 & (ANSSEN   2ADAR  )NTERFEROMETRY   $ORDRECHT  4HE .ETHERLANDS +LEWER !CADEMIC  0UBLISHERS    ( :EBKER AND 2 'OLDSTEIN  h4OPOGRAPHIC MAPPING FROM INTERFEROMETRIC SYNTHETIC APERTURE RADAR  OBSERVATIONS v * 'EOPHYS 2ES  VOL   PP n    3 -ADSEN  ( :EBKER  AND * -ARTIN  h4OPOGRAPHIC MAPPING USING RADAR INTERFEROMETRY v  )%%%  4RANS 'EOSCIENCE AND 2EMOTE 3ENSING  VOL   PP n    ! 'ABRIEL  2 'OLDSTEIN  AND ( :EBKER  h-APPING SMALL ELEVATION CHANGES OVER LARGE AREAS  $IFFERENTIAL RADAR INTERFEROMETRY v * 'EOPHYS 2ES  VOL   PP n    $ -ASSONNET AND + &EIGL  h2ADAR INTERFEROMETRY AND ITS APPLICATION TO CHANGES IN THE %ARTHS  SURFACE v 2EV 'EOPHYSICS  VOL   PP n  . £n°ÈÈ  2!$!2 (!.$"//+   - "ORN AND % 7OLF   0RINCIPLES OF /PTICS  .EW 9ORK 0ERGAMON 0RESS  -ACMILLAN    & 'ATELLI  ! 'UARNIERI  &  0ARIZZI  0 0ASQUALI  # 0RATI   AND & 2OCCA  h4HE WAVENUMBER SHIFT IN  3!2 INTERFEROMETRY v )%%% 4RANS 'EOSCIENCE AND 2EMOTE 3ENSING  VOL   PP n    ( :EBKER AND * 6ILLASENOR  h$ECORRELATION IN INTERFEROMETRIC RADAR ECHOES v  )%%%  4RANS  'EOSCIENCE AND 2EMOTE 3ENSING  VOL   PP n    ! &ERRETTI  # 0RATI  AND & 2OCCA  h.ONLINEAR SUBSIDENCE  RATE ESTIMATION USING PERMANENT SCAT 
 FERENCE PATTERNS ARE SCANNED SIMULTANEOUSLY 4HE DIFFERENCE 
 1968.  3. Goldberg, H.: Some Notes on Noise Figures, Proc. 
 TION PHASE 7ITH A SPHERICAL OR QUADRATIC LAW OF INSERTION PHASE VARIATION  AS OBTAINED WITH OPTICAL 
 The data was recorded at latitude 23.6 S, longitude 133.1 E. ch20.indd   41 12/20/07   1:16:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Popoli, Design and Analysis of Modern Tracking Systems , Boston: Artech,  1999. 45. R. 
 4, pp. 5-14, 1958.  72. 
 PULSE BINOMIAL 
 R., C. J. Morgan, and D. 
 8. R. Andraka, “A survey of CORDIC algorithms for FPGA-based computers,” in ACM /SIGDA  International Symposium on Field Programmable Gate Arrays , Monterey, CA, February 1998,  pp. 
 CONTROLLED TUBES AND CROSSED 
 Duct formation by thunderstorms may not be as  frequent as other ducting mechanisms, but it is of importance since it may be used as a means  of detecting the presence of a storm. An operator carefully watching a radar display can detect  the presence of a storm by the sudden inc·rease in the number and range of ground targets. The  conditions appropriate to the· formation I of a thunderstorm duct are short-lived and have a  time duration of the order of'perhaps 30 min to 1 h. 
 396-401, IEEE Publication 75 CHO 938-1 AES.  64. Clark, B. 
 Received IF signals are passed through a bandpass filter matched to the subpulse width and are demodulated by / and Q phase detectors. The / and Q detectors compare the phase of the received IF signal with the phase of a local-oscillator (LO) signal at the same IF frequency. The LO signal is also used in the RF modulator toCode-l1100111010000010110010000 Code-00011000101101010110010000N-26N-26 2N-52 . 
 STATE DEVICE  HAS NOT HAD SIGNIFICANT APPLICATION IN RADAR 'YROTRONS )F VERY HIGH POWER IS NEEDED AT MILLIMETER 
 Range gating eliminates excess receiver noise and clutter  from competing with the signal and permits target tracking and range measurement.  The range gate is typically matched to the bandwidth of the transmit pulse. In a surveil - lance radar, a number of receiver gates are used to detect targets that may appear at  any range within the interpulse period. 
 The elevation shap- ing, azimuth beam skirts, and side- lobes are closely controlled by the use of the computer-aided design process. A limitation of shaped reflectors is that a large fraction of the aperture is not used in forming the main beam. If the feed pattern is symmetrical and half of the power is directed to wide angles, it follows that the main beam will use half of the aperture and have double the beamwidth. 
 fd tDoppler Historien   Figure 10.5  Progression of the Doppler frequency for successive resolution cells  (Doppler histories).   Since the curvature of the iso -Doppler contours for transverse objects is very slight and the  changes are almost linear, the Doppler history frequencies also progress linearly.  The task of  the analysis with SAR consists of separating the Doppler criteria, thereby to determine and  represent the cell amplitudes. 
 Small  range-tracking errors cause significant errors in calculated target angle based on the  range measurements. These errors must be fully understood to assess the performance  of multilateration systems. Target-caused range-tracking errors, similar to target-caused angle errors, are  greater than the wander of the target center of gravity and can fall outside the target  span.41 Figure 9.25 shows typical samples of spectral-energy distributions and prob - ability density functions for different target configurations. 
 The nature of the  surface roughness can be inferred from the radar echo, as can the dielectric properties of the  scattering surface. The former has been applied to the measurement of sea state (from satel­ lites), and the latter was used in early radar astronomy to probe the nature of the moon's  surface.  11.3 THEORETICAL ACCURACY OF RADAR 1VIEASUREMENTS  The ability of a radar to detect the presence of an echo signal is fundamentally limited by noise. 
 TO 
 ETER MEAN  THRESHOLD CAN BE USED )F THE SAMPLES ARE DEPENDENT  ONE CAN EITHER USE  4HRESHOLDING  4ECHNIQUE4ARGET  3EPARATION3. OF 4ARGET NO       !LL REFERENCE CELLS                     2EFERENCE CELLS WITH MINIMUM MEAN VALUE                            AFTER ' 6 4RUNK Ú )%%%  4!",%  0ROBABILITY OF $ETECTING "OTH 4ARGETS WITH ,OG 6IDEO 7HEN THE 4WO 4ARGETS !RE  3EPARATED BY       OR  2ANGE #ELLS 3. OF TARGET  IS  D" AND 3. OF TARGET  IS          OR  D"  . 
 7LL    &)'52%   3LANT AND GROUND PLANES 4HE SLANT PLANE IS DETERMINED  BY THE RADAR LINE 
 ................................ ................................ ............................ 
 Kummer, W. H.: Feeding and Phase Scanning, chap. 1 in "Microwave Scanning Antennas, vol. 
 , 9Ê 9-Ê"Ê  , 4HE USE OF COMMERCIAL MARINE RADAR AROSE DIRECTLY FROM THE RAPID DEVELOPMENT OF RADAR TECHNOLOGY FOR MILITARY APPLICATIONS DURING 7ORLD 7AR )) %VEN AS EARLY AS   SOME ATTENTION WAS BEING GIVEN TO THE PEACETIME ROLE OF RADAR AS A NAVIGATIONAL AID FOR COMMERCIAL SHIPPING )N   AN h)NTERNATIONAL MEETING ON RADIO AIDS TO MARINE NAVIGATIONv WAS HELD IN ,ONDON AND ATTENDED BY REPRESENTATIVES FROM  COUNTRIES   4HE MEETING WAS CHAIRED BY 3IR 2OBERT 7ATSON 
 This was recorded in ‘The Minutes of a Special meeting held in Room 71/II, Air Ministry, Whitehall on Wednesday 27th October 1943 at 1545 hours ’[1], marked ‘Most Secret ’. This meeting was chaired by Sir Robert Renwick, Bt, (Controller of Communications, Air Ministry) and attended by about 30 others, including Dr A C B Lovell, TRE. At this meeting it was agreed that 200 3cm equipments would be produced for four squadrons, three for BomberCommand and one for Coastal Command (ASV Mk VII). 
    -ARCH   h7ORLD DISTRIBUTION AND CHARACTERISTICS OF ATMOSPHERIC RADIO NOISE v ##)2 2EPT    ##)2  )NTERNATIONAL 2ADIO #ONSULTATIVE #OMMITTEE   )NTERNATIONAL 4ELECOMMUNICATIONS 5NION  EDITIONS      AND   ! $ 3PAULDING AND * 3 7ASHBURN  h!TMOSPHERIC RADIO NOISE 7ORLDWIDE LEVELS AND OTHER CHAR 
 M. Morey, “Continuous sub-surface profiling by impulse radar,” in Proc. Conf. 
 &IELD !MPLIFIER  !LTHOUGH THESE TUBES WERE EMPLOYED FOR SOME MAJOR  RADAR APPLICATIONS BECAUSE THEY HAVE GOOD EFFICIENCY  REQUIRE RELATIVELY LOW VOLTAGE  AND HAVE WIDE BANDWIDTH ABOUT    THEY ARE LESS LIKELY TO BE USED BECAUSE THEY ARE NOISY WHICH AFFECTS THEIR DOPPLER 
 As, this is the basic principle of many radar systems,  . SHORT, SHARP SHOUTS 39  and of the use of a CRT for basic radar display, you  would be well advised to read the last two pages very  carefully over again, not taking any statement for  granted, but making sure you have a thorough grasp  of how the CRT acts as our electron stop-watch.  Of course, the process is continuous. 
 July,1956. 56.ABriefDescription oftheASR-8AirportSurveillance Radar.Tl'XlISJllsrrl/ml'llfs. Jill'..SP05A-Hi76. 
 Another method for utilizing the frequency  domain to scan an angular region is to radiate a single frequency-modulated pulse with a  modulation-band wide enough to scan the beam over the entire angular region. Thus, over the  duration of a single pulse, the antenna beam scans all angles. This is sometimes called ,ritl~irr-  pulse frequency ~cannin~.~~.'~~ (The term within-pulse scanning has been applied to other  methods of scanning, as described in Sec. 
 RATE SITES  AND THE RADAR IS STILL CONSIDERED TO OPERATE MONOSTATICALLY &OR EXAMPLE   AN OVER 
 At each sever, the modulated beam carries the signal forward, while the power trav- eling in the slow-wave circuit at that point is dissipated in the sever loads; thus reverse-directed power is stopped at each sever. The sever loads may be placed external to the tube to reduce dissipation within the RF structure itself. TWTs tend to be less efficient than klystrons because of the necessity for loading the structure for stability and because relatively high RF power is present in an appreciable fraction of the entire structure. 
 The power-handling capability of the balanced duplexer is inherently greater than that of  the branch-type duplexer and it has wide bandwidth, over ten percent with proper design. A  receiuer protector, to be described later, is usually inserted between the duplexer and the  receiver for added protection.  Another form of balanced duplexerJg uses four ATR tubes and two hybrid junctions  (Fig. 
 £°ÎÓ  2!$!2 (!.$"//+  FREQUENTLY IN CLEAR AIR 4HE 6!$ TECHNIQUE IS MOST OFTEN APPLIED TO WIND PROFILER RADARS  THAT POINT VERTICALLY AND STEP SCAN AT RELATIVELY LARGE ELEVATION ANGLES !N ALTERNATIVE DETERMINATION OF BOUNDARY LAYER WIND FIELDS USING A SINGLE WEATHER RADAR HAS FOUND SUCCESS USING AN ECHO TRACKING TECHNIQUE  4HUNDERSTORM 0REDICTION  7ILSON AND 3CHREIBER ILLUSTRATE HOW METEOROLOGI 
 SCATTERING CHARACTERISTICS OF THE SEA IN  THE REGION FROM  TO  +-# v 0ROC )2%  VOL   PP n    ' 7 %WELL  - - (ORST  AND - 4 4ULEY  h0REDICTING THE PERFORMANCE OF LOW 
 OUSLY  ATTEMPTING TO MATCH THE DETECTIONS TO A hTARGET 
 Signal Processing. There has not always been general agreement as to what constitutes the signal-processing portion of the radar, but it is usually considered to be the processing whose purpose is to reject undesired signals (such as clutter) and pass desired signals due to targets. It is performed prior to the threshold de- tector where the detection decision is made. 
 This was done in Wetzel,12 where it is shown how diffraction, rather than geometrical  shadowing, controls propagation into and out of the troughs of the waves under many  of the usual frequencies and wind speeds encountered in practical radar operations at  low grazing angles. For example, shadowing will take place at Ka band for any winds  above 15 kt, yet will hardly ever occur at L-band frequencies. Later analytical solu - tions based on numerical methods explored and expanded the idea of shadowing over  the sea surface under highly idealized,76 and more general77 conditions. 
  
 FIELD VOLTAGE  PATTERN CAN BE CONSIDERED TO BE THE SUM OF THE DESIGN PATTERN PLUS THE PATTERN CREATED SOLELY BY THE ERRORS   %% % 4        PP PFF F  DESIGN ERROR  )N GENERAL  THREE REGIONS WILL BE RECOGNIZED IN THE TOTAL RESULTANT PATTERN A LOW  NOISE FLOOR GENERATED BY RANDOM ERRORS THAT FOLLOW THE ELEMENT PATTERN  A FEW PEAK  SIDELOBES DUE TO CORRELATED ERRORS  AND THE MAIN BEAM WITH ITS SIDELOBES DUE TO THE DESIGN DISTRIBUTION 2ANDOM %RRORS  !LLEN  AND 2UZE HAVE MADE DETAILED ANALYSES OF THE EFFECTS  OF RANDOM ERRORS ON ANTENNAS 4HIS DISCUSSION WILL FOLLOW THE ANALYSIS PERFORMED BY !LLEN !S PREVIOUSLY MENTIONED  AMPLITUDE AND PHASE ERRORS TAKE A FRACTION OF THE ENERGY FROM THE MAIN BEAM AND DISTRIBUTE THIS ENERGY TO THE SIDELOBES 4HIS FRACTION IS  FOR SMALL INDEPENDENT RANDOM ERRORS    SSSF4!    WHERE RE   RMS PHASE ERROR  RAD  R!   RMS AMPLITUDE ERROR  VOLTSVOLT 66  4HIS ENERGY IS RADIATED INTO THE FAR FIELD WITH THE GAIN OF THE ELEMENT PATTERN  4O DETERMINE THE MEAN 
 The local oscillators act essentially as a timing standard by which the echo delay is measured to extract range information, accurate to within a small frac- tion of a wavelength. The processing demands a high degree of phase stability . throughout the radar. 
 BOARD THE %23 
 WIDTH FOR SCANNING TO o n HAS BEEN ACHIEVED ,IMITED 3CANNING  )F SCANNING IS LIMITED TO A SMALL ANGULAR VOLUME  CONSIDERABLE  SIMPLIFICATIONS BECOME POSSIBLE 4HE TOTAL NUMBER OF ACTIVE CONTROLS CAN BE REDUCED TO .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°Ç ABOUT EQUAL THE TOTAL NUMBER OF BEAMS 3UBARRAYS SEE 3ECTION   MAY BE FORMED   EACH WITH ONLY ONE PHASE CONTROL OF A SIZE SUCH THAT THE SUBARRAY BEAMWIDTH INCLUDES ALL THE SCAN ANGLES !LTERNATIVELY  A SMALL PHASED ARRAY COULD BE PLACED IN THE FOCAL REGION OF A LARGE REFLECTOR TO SCAN THE NARROW BEAMWIDTH OF THE REFLECTOR OVER A LIMITED SCAN ANGLE 3CANNING OF !RRAYS 0HASE 3CANNING  4HE BEAM OF AN ANTENNA POINTS IN A DIRECTION THAT IS NORMAL  TO THE RADIATED PHASE FRONT )N PHASED ARRAYS  THIS PHASE FRONT IS ADJUSTED TO STEER THE  BEAM BY INDIVIDUAL CONTROL OF THE PHASE OF EXCITATION OF EACH RADIATING ELEMENT 4HIS  IS INDICATED IN &IGURE  A 4HE PHASE SHIFTERS ARE ELECTRONICALLY ACTUATED TO PERMIT  RAPID SCANNING AND ARE ADJUSTED IN PHASE TO A VALUE BETWEEN  AND  O RAD 7ITH AN  INTERELEMENT SPACING  S  THE INCREMENTAL PHASE SHIFT  X  BETWEEN ADJACENT ELEMENTS FOR A  SCAN ANGLE  P  IS X    O K S SIN P )F THE PHASE  X  IS CONSTANT WITH FREQUENCY  THE SCAN  ANGLE P IS FREQUENCY 
 */1 Ê, ,Ê-9-/ 
 TION COVERS BY 8 
  
 DRAIN SPACING OF THE &%4 GEOMETRY #RITICAL APPLICATIONS ARE USUALLY ONLY THE FRONT 
 2“dcpc,(lo) Ifone compares thegain-bandwidth products given above with those previously quoted forsingle-tuned circuits, itwill beseen that there isan improvement byafactor of3.8dbintheequal-Q case and byafactor of 6.8dbinthe case ofloading onone side only.2 There isthe further 1.Asthecoupling between twocircuits ofunequal Qisincreased from zero, the response atresonance rises toamaximum atthe“critical coupling” point andthen decreases (with aflatter and flatter toptotheresponse curve) until thepoint of “transitional” coupling isreached, after which thecurve becomes “double-humped.” Ifthetwo circuits hnve equal Q’s, transitional coupling and critictd coupling are thesame. 2Values ofC=andC,of7and14ppf,respectively, were used forthiscalculation.. 448 THERECEIVING SYSTEM—RADAR RECEIVERS [SEC. 
 Solem, and R. F. Van Wye: " Regulations, Standards, and Guides for  Microwaves. 
 LAP 
 This results in a smaller rms tracking noise with a slow  AGC system.39,40 However, this reasoning neglects an additional noise term, caused by the lack of  full AGC action, which is proportional to tracking lag. A tracking lag causes a dc error   ch09.indd   33 12/15/07   6:07:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
  
 NOISE MARGIN OF  
   $ECEMBER     , 2 -OYER  h#OMMENTS ON @2ECEIVER ANTENNA SCAN RATE REQUIREMENTS NEEDED TO IMPLEMENT  PULSE CHASING IN A BISTATIC RADAR RECEIVER v  )%%% 4RANS ON !EROSPACE AND %LECTRONIC 3YSTEMS   VOL   NO   P   *ANUARY   CORRESPONDENCE  * &RANK AND * 2UZE  h"EAM STEERING INCREMENTS FOR A PHASED ARRAY v  )%%% 4RANS  VOL !0 
 Doviak, “Spaced-antenna interferometry to measure crossbeam wind, shear and  turbulence: Theory and formulation,” J. Atmos.  Ocean. 
 Speciﬁcally, the sliding windowing manipulation is implemented by the short time Fourier transform (STFT). The two sub-view images at the same range cell are individually processed by the STFT, followed by the conversion of the data dimension from one to two, where one denotes the original Doppler frequency and the other denotes the newly-generated frequency. After the conjugate multiplication of the data, the IFFT is generated along the new frequency axis. 
 - 3HORT COURSE NOTES AND OTHER PAPERS CAN USUALLY BE OBTAINED FROM THE AUTHORS OR THE COURSE SPONSOR FOR  A SMALL FEE !LL OF THE AUTHORS PAPERS REFERENCED ARE AVAILABLE IN !DOBE !CROBAT FORMAT SUBJECT ONLY TO COPYRIGHT RESTRICTIONS BY E 
 3.5 Frequency responses of radar receiver. varying weights. This MTI exaggerates certain stalo modulation frequencies by as much as 5 dB more than average. 
 STEERED TO MAINTAIN AZIMUTH ANTENNA BORESIGHT POINTING AT ZERO DOPPLER  WHICH INCREASES THE LIKELIHOOD OF PASS 
 127-131, April 1961. 4. Cutrona, L. 
 Cantafio, L. J., and J. S. 
 MENT -ODELING TECHNIQUES INCLUDE SINGLE FREQUENCY MODELS  TIME 
 /,"  Ê7,, 
 POWER POINTS v OR POINTS WHERE THE INTENSITY POWER  PROPORTIONAL TO VOLTAGE SQUARED  IS ONE HALF  OR  
 Thus, the number of sub-arrays is a trade-off between  hardware complexity, cost, and achievable performance. ch24.indd   25 12/19/07   6:00:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 3/* 4!2'%4 ./,/34 4!2'%43 4S S  4AVE S  0- 7 0/3 %22 M 6%,%22 MS       n           n       n     4!",%  3IMULATION 2ESULTS 7ITH 2'0/ AND 7ITHOUT ! 
 C. A. Samson. 
 This case more clearly shows the difference in the fusion methods. For example, when two identical radars are combined by detection fusion, then  the update rate is essentially doubled. This reduces the lag by a factor of 4, allowing a  smaller gain to be selected (optimization more to the left of the “bathtub”), reducing  the tracking errors due to measurement noise. 
 MING  AND NARROW BAND INTERFERENCE )F THE RADAR EMPLOYS A PHASE 
 The comparison may bemade either bymeasuring the vector 1Since refraction ofone-half degree ispossible, andsince variations ofecho strength duetoaspect canbe12db,altitude errors ofseveral thousand feetcanoccur even in thefavorable case ofseareflection.. 186 THEGATHERING ANDPRESENTATION OFRADAR DATA [%c.6.11 resultant ofsimultaneously received signals (asisdone inthe CH by means ofagoniometer; seeSec. 6.9), orbypresenting alternately received signals side-by-side inatype Kdisplay and estimating visually their ratio inheight. 
 3TATE !MPLIFIERS FOR 2ADAR 4RANSMITTERS  3OLID 
 Straiton. and C. 0. 
 The large sidelobes are often objectionable since a large target might mask nearby, smaller  targets. Also, near-in sidelobes might at times be mistaken for separate targets. These sidelobes  can be reduced by amplitude weighting of the received-signal spectrum, just as the spatial  side lobes of an antenna radiation pattern can be reduced by amplitude weighlirlj the illumina­ tion across the antenna aperture, as was described in Sec. 
 TORS VARIES WIDELY  BUT SOME OF THE FACTORS THAT ARE TYPICALLY SIGNIFICANT INCLUDE THERMAL  VIBRATION  AND EXPOSURE EG  SALT  SAND  WATER  RADIATION  ETC  4HERMAL EFFECTS  IE  SPATIAL OR TEMPORAL TEMPERATURE VARIATIONS  ARE OF PARTICULAR CONCERN FOR SPACEBORNE SENSORS THAT OFTEN SEE VERY SIGNIFICANT TEMPERATURE CHANGES GREATER THAN  # TEM 
 Serafin National Center for Atmospheric Research (CHAPTER 19) William W. Shrader Shrader Associates (CHAPTER 2) Merrill Skolnik (CHAPTERS 1 and 10) Fred M. Staudaher Naval Research Laboratory, retired (CHAPTER 3). 
 TER INPUT INTO ONE PORT ENERGIZES BOTH HALVES OF THE APERTURE  FOR EXAMPLE  IN PHASE 4HE RECEIVER  CONNECTED TO THE REMAINING PORT  THEN REQUIRES THAT THE PHASE SHIFTERS OF HALF THE APERTURE GIVE AN ADDITIONAL PHASE SHIFT OF  O  DURING THE RECEIVING PERIOD 4HIS  IS EASILY PROGRAMMED -ULTIPLE RECEIVE BEAMS MAY BE FORMED BY COMBINING THE SUBARRAYS AFTER AMPLIFICA 
 MENTED AS TWO CASCADED  
 High angle-error sensitivity is desired to obtain higher voltage from the angle error detectors for a given true angle error relative to undesired voltages in the receiver output. The undesired receiver output includes angle errors caused by receiver thermal noise. For a given signal-to-noise ratio (SNR) the thermal-noise effects are inversely proportional to angle error sensitivity. 
 They transmit, on a  repetitive basis, a nominally constant amplitude signal whose frequency increases in a  linear progression from the lowest to the highest value. Recovery of the receiver signal from noise may be achieved by either conventional  bandpass filters or by the matched filter or Wiener filter. The fundamental operation of a matched filter is correlation. 
 When theindex ofrefraction ishigh, Eq. (16) gives (17) Ifitisremembered that the coefficient fortheinternal reflection atthe front surface is–a,thefollowing table can beconstructed. TABLE 31.-EMERGENT RAYS AFTEE MULTIPLE REFLECTION No. 
 ITY TO ADJUST THE RANGE OF FREQUENCIES OF OPERATION TO SUIT THE MATERIAL AND TARGETS AND ELECTROMAGNETIC ENVIRONMENT UNDER INVESTIGATION IF THE ANTENNA HAS AN ADEQUATE PASS 
 H.. and H. V. 
 NOISE RATIO FROM EACH RADAR RESOLUTION CELL IS THE INTEGRAL OF %Q   OVER THE DOPPLER AND RANGE EXTENT OF EACH OF THE AMBIGUOUS CELL POSITIONS ON THE GROUND n 5NDER CERTAIN SIMPLIFIED CONDITIONS  THE INTEGRATION CAN BE CLOSED 
 Primary interest in fully polarimetric radars derives from the enriched scattering  observation possibilities revealed through replacement of the scalar form of reflectiv - ity by its complex vector counterpart.41,57,59  Thus, when either H or V polarizations are  incident on a scattering element, both polarizations are backscattered according to  E ES S S SE EHB VBHT VT  =    HH HV VH VV (18.14) where the superscript B denotes the field components reflected back toward the radar.  The new terms of interest represent the scene’s 2 × 2 scattering matrix, an array of four  complex numbers. Each element in this backscattering matrix expresses the magni - tude and phase imposed onto the backscattered field (superscript B) in response to the  illumination from the transmitted field (superscript T), according to their respective  polarizations. 
 concept, however, is not appropriate for discussion here. Instead, a brief review will be given of  the various .radar-ECCM options that can make the task of ECM more difficult.  As a general rule, good radar design practice can reduce vulnerability to electronic  countermeasures. 
 It can also be accounted for by an increase of the doppler filter noise bandwidth instead of as a separate loss. Pulse Compression Mismatch Loss. This is caused by the intentional mis- matching of the pulse compression filter to reduce the time (range) sidelobes. 
 Instead of the collector electrode found in the klystroti and the  TWT. the spent electroils terminate in the crossed-field amplifier on the slow-wave anode  struct ilrc.  T11e CFA depicted in Fig. 
 The need for a residual control voltage meant that a residual error of about 0.25 Mc/s was achieved in normal operation. The discriminator could not correct beat frequencies below 38 Mc/s or above 52 Mc/s. When this occurred, the local oscillator would be made to sweepover its full frequency range until a suitable beat frequency was obtained. 
 Stegen, R. J.: Gain of Tchebychcff Arrays. lEEE Traru.. 
 Thus, as a  practical matter, 106 m2 discretes are rarely present, 105 m2 are sometimes present, and  104 m2 are often present. Two mechanizations for detecting and eliminating false reports from sidelobe dis - cretes are the guard channel and postdetection sensitivity time control (STC). These  are discussed in the paragraphs that follow. 
 Digital multi-beamforming is used to obtain SAR data from different angles. The digital T/R modules are divided into three groups and three sets of receiving feeders are used to obtain the multi-beam signals in the time domain. On this basis, an improved RMA in a uniﬁed coordinate system is proposed. 
 %!   &)'52%  %LEMENT SPACE POST 
 Short-term coherent change detection may be used to separate stationary targets from  slow-moving endoclutter targets. Short-term coherent change detection is a method in  which two coherent SAR maps taken within a few hours of one another at the same  frequency are registered and cross-correlated pixel by pixel. The fast-moving target  category usually includes both targets and bullets or missiles.FIGURE 5.38  Typical GMT weapon guidance ( adapted8; courtesy SciTech Publishing ) FIGURE 5.39  Cartographic-assisted GMT geolocation94 ch05.indd   41 12/17/07   1:27:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 CONVERSION OR ANALOG  &)'52%     A  4IME 
 It is a typical city to study the problem of land subsidence in China. Previous studies have mapped land subsidence in Wuhan city using advanced InSAR methods [ 5,41,42]. However, longtime monitoring of land subsidence covering all urban areas of Wuhan city is lacking. 
 AIR 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.80  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 A/D converters are typically characterized by their signal-to-noise ratio (SNR)  performance referred to a bandwidth equal to the A/D sampling rate. 
 The separations between clutter larger than 10 m2 was be­ tween 135 and 675 m. For clutter which was greater than 0.1 m2, the patch sizes varied from  2 m to well over 300 m in length. The majority of these clutter-patch separations were less  than 30 m but a few exceeded 110 m. 
 S/)(}(chqfj'istheIlameusuallyassociated with thedeception role,whilecorridor cJ/l~fnsaconfusion countermeasure. Spotchaffisdropped as individual bundles whichappearasadditional targetsontheradarinanefforttodeceivethe operator astotheirtruenature. Achaffcorridor isproduced byair.craft continuously releasing chafftoformalong corridorlike cloudthrough whichfollowing aircraftcanflyundetected. 
 Percentage correct classiﬁcation (PCC) and Kappa coefﬁcient (KC) are as follows: PCC =(Nc−FN)+( Nu−FP) Nu+Nc×100%, KC=PCC−PRE 1−PRE, where proportional reduction in error (PRE) is deﬁned as PRE =(Nc−FN+FP)·Nc+( Nu−FP+FN)·Nu (Nu+Nc)2. The results of the quantitative metrics are given in Table 1. T able 1. 
 RANGE REQUIREMENTS INTO THE DOPPLER FILTER BANK IF THE MAIN 
 The  product kTo is equal to 4 × 10−21 W/Hz. To account for the additional noise introduced  by a practical (nonideal) receiver, the thermal noise expression is multiplied by the  noise figure Fn of the receiver, defined as the noise out of a practical receiver to the  noise out of an ideal receiver. For a received signal to be detectable, it has to be larger  than the receiver noise by a factor denoted here as ( S/N)1. 
 The code elements air for i = O, 1, 2,..., N — 1 are 1 if i is a qua- dratic residue modulo N and -1 otherwise. Quadratic residues are the remainders where x2 is reduced modulo N for x = 1, 2,..., (N - 1)12. As an example, the qua- dratic residues for N = 11 are 1, 3, 4, 5, 9. 
 BIN RADARS v )%%% 4RANS  VOL !%3 
 Lewis, R. M.: Physical Optics Inverse Diffraction, IEEE Trans., vol. AP-17, pp. 
 R. Lhermitte, “A 94-GHz doppler radar for cloud observations,” J. Atmos. 
 OFFSET ERROR TO THE PULSE REPETITION FREQUENCY 02&  FOR DIFFERENT CLUTTER SPECTRAL WIDTHS &ORTUNATELY  THE PLATFORM 
 Ê 9Ê, 
 Warner: Weather Effects on Radar, in Skolnik, M. (ed.): "Radar Handbook," McGraw-Hill Book Company, New York, 1970, pp. 24-1-24-40. 
 VEILLANCE RADAR )T CAN HAVE A VERY LARGE NUMBER OF TARGETS IN TRACK BY USING THE  MEASUREMENTS OF TARGET LOCATIONS OBTAINED OVER MULTIPLE SCANS OF THE ANTENNA )TS DATA RATE IS NOT AS HIGH AS THE 344 2EVISIT TIMES MIGHT RANGE FROM ONE TO  SECONDS  DEPENDING ON THE APPLICATION 4RACK 
 TINUOUSLYv TRACK MORE THAN ONE TARGET AT A HIGH DATA RATE )T CAN ALSO SIMULTA 
   !. ).42/$5#4)/. !.$ /6%26)%7 /& 2!$!2   £° #OMMISSION  AND INTERNATIONALLY  THE )NTERNATIONAL 4ELECOMMUNICATIONS 5NION  !FTER  THE SUCCESS OF RADAR IN 7ORLD 7AR ))  RADAR WAS ALLOWED TO OPERATE OVER ABOUT ONE 
 543–599. 128. H. 
 VOLUME (ft3) FIG. 11.19 Summary of RCS levels of targets dis- cussed in this section. The locations of targets on the chart are general indications only. 
 DETECTION OF RADAR SIGNALS IN NOISE 397  47. Benjamin, R.: Man and Machine in the Extraction and Use of Radar Information, J. Brit. 
   OR MILLISECOND TIME REGION 4HE INCREMENTATION OF THE SAMPLING INTERVAL IS TERMINATED AT A STAGE WHEN  FOR EXAMPLE      OR  SEQUENTIAL SAMPLES HAVE BEEN GATHERED 4HE PROCESS IS THEN REPEATED 4HERE ARE SEVERAL METHODS OF AVERAGING OR hSTACKINGv THE DATA EITHER A COMPLETE SET OF SAMPLES CAN BE GATHERED AND STORED AND FURTHER SETS ADDED TO THE STORED DATA SET  OR ALTERNATIVELY  THE SAMPLING INTERVAL IS HELD CONSTANT FOR A PREDETERMINED TIME TO ACCUMULATE AND AVERAGE A GIVEN NUMBER OF INDIVIDUAL SAMPLES 4HE FIRST METHOD NEEDS A DIGITAL STORE BUT HAS THE ADVANTAGE THAT EACH WAVEFORM SET SUFFERS LITTLE DISTORTION IF THE RADAR IS MOVING OVER THE GROUND 4HE SECOND METHOD DOES NOT NEED A DIGITAL STORE AND A SIMPLE LOW 
 1965.  81. Karrfrnan. 
 Diagnosis of trouble, repair, and readjustment, aswell asassessment ofperformance, can allbeperformed onawell-equipped test bench. This isparticularly helpful forairborne sets. Good engineering practice favors pressurization ofther-ftransmission lines ofmicrowave radar systems inorder tokeep out water and water vapor. 
 PREFERRED GROUND STABILIZATION SOURCE FOR RADAR  EVEN FOR A SHIP FITTED WITH A DOPPLER LOG $OPPLER LOGS DO NOT ALWAYS GIVE GOOD SPEED READINGS ON SOME TYPES OF SEABED  FOR EXAMPLE  SOFT MUD &ACILITIES MUST ALSO BE PROVIDED TO ALLOW THE USE OF STATIONARY TRACKED TARGETS  SUCH AS RADAR CONSPICUOUS NAVIGATION MARKS  TO PROVIDE THE GROUND REFERENCE !CCORDING TO THE DESIGN  THE BASIC TRACKING FUNCTION CAN BE CARRIED OUT IN SHIP OR  GROUNDSEA REFERENCED FRAMES  USING CONVENTIONAL ALGORITHMS 4HE TRACKING PROCESS CAN BE INITIATED MANUALLY OR AUTOMATICALLY !UTOMATIC INITIATION IS BY A CONVENTIONAL PLOT EXTRACTION PROCESS CONFINED WITHIN A USER 
 Test dataset. Label T est Bulk Carrier 38 Container Ship 16 Oil Tanker 16 All of the experiments have been done several times, and we listed the average results of the experiments. 3.4. 
 ICE APPLICATION HAD HIGH PRI 
 15.7  was redefined in terms of a more realistic tapered footprint, adding another 1 to 2 dB.  This means that there can be a difference of 3 to 4 dB between the earlier and later  presentations of the same data, and since these results have been widely used and  quoted, it is important to ensure that the proper definition of s  0 is being used when  comparing them with clutter data that has been taken by other experimenters or in  using these results in clutter predictions. Figure 15.2 shows that even for intermediate grazing angles in the range 20°–70°  the sea clutter distribution departs from strictly Rayleigh. 
 Fujita, T.: 'The Downburst," Satellite and Mesometeorology Research Project, De- partment of the Geophysical Sciences, University of Chicago, 1985. 67. Fujita, T.: "The DFW Microburst," Satellite and Meteorology Research Project, De- partment of the Geophysical Sciences, University of Chicago, 1986. 
 RANGE APPLICATIONS  THE BEST PER 
 £ä°£Ó  2!$!2 (!.$"//+  #LUSTERED 
 Cohen, I.; Levanon, N. Weight Windows—An Improved Approach. In Proceedings of the 2014 IEEE 28th Convention of Electrical & Electronics Engineers in Israel (IEEEI), Eilat, Israel, 3–5 December 2014. 
 PULSE STAGGERING WILL NOT PROVIDE CANCELING OF CLUTTER IN  THE AMBIGUOUS RANGE INTERVALS 7ITH DWELL 
   PP n  *UNE   ' * ,INDE ET AL PRIVATE COMMUNICATION   h7ARLOC ! HIGH 
 12.White,W.D.:Synthesis ofCombFiiters,Proc.Natl.Conf.011Aeronaut. Electronics, 1958,pp.279-285. 13.Urkowitz, H.:Analysis andSynthesis ofDelayLinePeriodic Filters,IRETrans.,vol.CT-4,pp.41-53, June,1957. 
 SIDERED FOR OUTDOOR USE  /NE OF THREE CONFIGURATIONS MAY BE SELECTED  ALL REQUIRING  A CUSTOM 
 1, pp. 19–24, February 1998. 181. 
 Younis, C. Fischer and W. Wiesbeck, “Digital beamforming in SAR systems”, IEEE Transactions on Geoscience and Remote Sens ing, vol. 
 POL AT  n OFF 
 A narrow tracking filter tracks the cross- .. 7  over of the two spectra. The frequency of this crossover is the same for water as for land. 
 7. Helstroni. C. 
 10.Ib. Identical filters may be used for both expansion and compression, or the same filter may be used for both expansion and compression with appropriate switching between the transmitting and receiving functions. The output of this matched filter is given by the convolution of the signal h(t) with the conjugate impulse response h*(— t) of the matched filter: OO y(t) = fh(i)h*(t - T)^T — 00 The matched filter results in a correlation of the received signal with the trans- mitted signal. 
 Rotation ofthe range handwheel also brings the signal being tracked into the center ofthe azimuth and elevation display tubes. Each ofthese tubes ismanned byanoperator provided with ahandwheel which moves the antenna inthe appropriate angular coordinate. The display istype K(Fig. 
 5.5 'I'AH(;E;'I'-UEF1,EC'TION CI IAUAC'I'ERISTICS AND ANGULAR ACCUHACY".~ 1-95  I Ilc angular accuracy of tracking radar will be il~fluetlced by such factors as the nieclla~lical  properties of the radar antenna and pedestal, the method by which the angular position of the  antenria is measured, the quality of the se-, the stability of the electronic circuits, the  noise level of the receiver, the antenna beamwidth, atmospheric fluctuations, and the reflection  characteristics of the target. These factors can degrade the tracking accuracy by causing the  antenna beam to fluctuate in a random manner about the true target path. These noiselike  fluctuations are sometimes called trackiltg ltoise, or jitter. 
 Whentheswathissignificantly lessthantheunambig­ uousrange,abuffercanbeinserted aftertheAIDconvertors toreadthedataoutataslower speedsoastoprocessatalowerdataratethaniftheentireunambiguous rangehadtobe imaged. Digitalprocessing alsoallowstheuseofanonlinear sweeptoconvertslantrangeto grounddistance soastomakedistances correctontheimage. Doppler-frequency model.Thesynthetic aperture radarmaybeconsidered asavectorsumma­ tionofsynthetic-array elements (whichisthemodelgenerally takeninthis section), oritmay beconsidered intermsofdoppler filtering. 
 This allowed the operator to pre- cisely and directly estimate the target height of the target by a process termed beam splitting, referring to the process of estimating the center of the displayed target video. Although some nodding-antenna height finders had a slow azimuth rotation search mode, most relied on designations of azimuth from an operator. The operator would observe a detection by the 2D surveillance radar and then command a height determination by the height finder. 
 HORIZON RADAR 2EMOTE 3ENSING OF THE %NVIRONMENT  4HE MAJOR APPLICATION IN THIS CATEGORY  HAS BEEN WEATHER OBSERVATION RADAR SUCH AS THE .EXRAD SYSTEM WHOSE OUTPUT IS OFTEN SEEN ON THE TELEVISION WEATHER REPORT 4HERE ALSO EXIST VERTICAL 
 Wilson and Roesli50 show an excellent example of a tornado vortex signature (TVS) embedded within a larger mesocyclone. Microbursts. Fujita and Caracena65 first identified the microburst phenome- non as the cause of an airliner crash that took place in 1975. 
 208 INTRODUCTION TO RADAR SYSTEMS  to those of the klystron, but they are generally more difficult than for the klystron. In some  traveling-wave tubes with coupled-cavity circuits; oscillations appear for an instant during the  turn-on and turn-off portions of the pulse. 1 They are called rabbit-ear oscillations because of  their characteristic appearance when the RF envelope of the pulse waveform is displayed  visually on a CRT. 
 111,"  R. C'. flansen (ed.), Academic Press, New York, 1966. 
 J  62. Becker, J.E., and R. E. 
 Finally, even if the importance of an environmental parameter has  been recognized, it is often difficult (or too expensive) to measure it accurately in the  field under real sea conditions. While many aspects of sea clutter thus remained frustratingly ill-defined, the  earlier work did disclose some general trends, such as the tendency of average  clutter signal strengths at low to intermediate grazing angles to increase with the Chapter 15 ch15.indd   1 12/19/07   2:46:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 However, the design tradeoffs have resulted in commonly partitioned circuits. Some of the design criteria or characteristics peculiar to amplifiers and other circuits as follows: LOW-NOISE AMPLIFIERS . (1) Multiple-stage linear designs require proper device siz- ing of successive stages in order to maintain low intermodulation distortion products. 
   PP n  -ARCH  3EE ALSO CORRECTION  VOL !0 
 The output ofthe mixer at each element is taken at the sun1  frequency. J', +f2, to give the required phase shifts for two-dimensional beam steering.  8.5 A HRAY ELE:ILIEN'I'S~~.~"  Airnost ally type of r;idiatirig a~iterinn elenierit can be considered for use in an array antenna. 
 As might be expected, no applications theme  would accept degraded resolution. To satisfy that demand, the radar design adopted  three bandwidths, so that the nominal ground-range resolution would be maintained  at ∼25 m over all baseline incident angles. As a corollary, the wider bandwidth at  shallower incidence would result in finer range resolution. 
 FORMANCE IN BAD WEATHER IS QUITE LIMITED 2ECEIVER NOISE IS DETERMINED BY QUANTUM EFFECTS RATHER THAN THERMAL NOISE &OR SEVERAL REASONS  LASER R ADAR HAS HAD ONLY LIMITED  APPLICATION £°ÇÊ , ,Ê " 
 WIND ASPECT  4HE RESULT 
 = R(t -ti)  -ro (10.17)  ( 10.18)  Thus the matched filter forms the cross correlation between the received signal corrupted by  noise and a replica of the transmitted signal. The replica of the transmitted signal is" built in"  to the matched filter via the frequency-response function. If the input signal y10(t) were the . 
 DOPPLER FILTER AND THE FIRST MOVING DOPPLER FILTER IS LARGER THAN THE OTHERS  PRIMARILY BECAUSE  UNDER THE CONSTRAINTS  IT IS IMPOSSIBLE TO MOVE THE FIRST DOPPLER FILTER NEARER TO ZERO VELOCITY #HEBYSHEV &ILTER "ANK   &OR A LARGER NUMBER OF PULSES IN THE #0)  A MORE SYSTEM 
 #7 SYSTEMS  W ITH CONSIDERATION  OF THE DOPPLER EFFECT  IS DESCRIBED IN 3HERMAN  !CQUISITION 4HE FIRST FUNCTION OF THE RANGE TRACKER IS ACQUISITION OF A DESIRED  TARGET !LTHOUGH THIS IS NOT A TRACKING OPERATION  IT IS A NECESSARY FIRST STEP BEFORE RANGE TRACKING OR ANGLE TRACKING MAY TAKE PLACE IN A TYPICAL RADAR 3OME KNOWLEDGE OF TARGET ANGULAR LOCATION IS NECESSARY FOR PENCIL 
 THE 
 ING $ETECTIONS ARE MADE ON TARGETS  BUT SOME DETECTIONS ARE MISSING BECAUSE OF TARGET FADES OR MULTIPLE TARGETS IN THE SAME RESOLUTION CELL  WHEREAS ADDITIONAL DETECTIONS ARE PRESENT DUE TO CLUTTER OR NOISE &)'52% A  4HIRTY 
 This hypothesis allows the use correlation-based algorithm to extract useful information from data. The use of SVD technique can give us information about the reference functions to focus the image. 2.2. 
 Conventions. Because of the wide variability of propagation-path and other range-equation factors, certain conventions are necessary for predicting range under standard conditions when specific values of those factors are not known. A convention is a generally accepted standard assumption, which may never be encountered exactly in practice but which falls within the range of con- ditions that will be encountered, preferably somewhere near the middle of the range. 
 The finer resolution pixels are  at the bottom, just as they are with a naturally oriented optical image. This orientation  tends to look most natural to a human observer. Because SAR imagery and optical imagery are collected using entirely  different  physical principles, we should not be surprised if they look different . 
 32, pp. 135-148, September, 1966. RADAR CLUTIER 513  24. 
 FACED LETTERS ARE VECTORS (ENCE  THE TOTAL FIELD IS GIVEN BY  %!J TK2DT K2ICI IIT 
 SEA INTERFACE 4HIS DUCT IS REFERRED TO AS AN EVAPORATION DUCT "ECAUSE THE EVAPORATION DUCT IS OF GREAT IMPORTANCE FOR OVER 
 LINES  ALL PARAMETERS OF OPERATIONAL INTEREST 4O REMEDY THIS PROBLEM  THE CONCEPT OF A BISTATIC BENCHMARK RANGE  OR MORE SIMPLY  BENCHMARK  IS INTRODUCED )T IS ESTABLISHED  AS FOLLOWS  &IRST  THE BISTATIC RADAR RANGE EQUATION IS DERIVED IN A MANNER COMPLETELY .   ")34!4)# 2!$!2   ÓÎ°x ANALOGOUS TO THAT FOR A MONOSTATIC RADAR 4HE EQUATION IS THEN SOLVED FOR THE  BISTATIC  MAXIMUM RANGE PRODUCT   24 22 MAX .EXT  AN  EQUIVALENT MONOSTATIC MAXIMUM RANGE    2- MAX  IS DEFINED OMITTING THE MAX SUBSCRIPT FOR CONVENIENCE  AS SHOWN HERE  2-   24 22     4HIS EQUIVALENT MONOSTATIC MAXIMUM RANGE  ALSO KNOWN AS THE  GEOMETRIC MEAN  RANGE  REPRESENTS PERFORMANCE OF THE BISTATIC RADAR WHEN TRANSMITTER AND RECEIVER ARE  CO 
 15. A. E. 
 The altimeter can employ a simple homodyne 71 receiver, but for better sensitivity and  stability the superheterodyne is to be prefered whenever its more complex construction can  be tolerated. A block diagram of the FM-CW radar with a sideband superheterodyne receiver  is shown in Fig. 3.13. 
 The key to robust CR is the fusion of all available information in a consistent probabilis - tic framework.141 Most radars implement target tracking as a separate stage that operates  on the candidate targets after they have been registered, initiating, updating, or terminat - ing tracks, as appropriate. Experience with many different types of tracking schemes  has led a number of operational radars to converge on algorithms based on variants of  probabilistic data association (PDA),142 sometimes generalized to maintain multihypoth - esis models.143 Unlike traditional tracking filters such as the Kalman filter, which selects  a single detection (i.e., peak or plot) to associate with each maintained track, PDA filters  combine the influence of all the candidate peaks within a prescribed radius to compute a  track update. In the skywave radar context, this has yielded superior results. 
 For  example, horizontal polarization might be employed with long range air-search radars operat-  ing at VHF or UHF so as to obtain longer range because of the reinforcement of the direct  radiation by the ground-reflected radiation, Sec. 12.2. Circular polarization is often desirable  in radars which must " see " through weather disturbances. 
 ERS BOTH THE 6(& AND 5(& BANDS 3UCH A RADARS SIGNAL BANDWIDTH MIGHT EXTEND  FOR INSTANCE  FROM  TO  -(Z ! WIDE BANDWIDTH IS NEEDED IN ORDER TO OBTAIN GOOD RANGE RESOLUTION 4HE LOWER FREQUENCIES ARE NEEDED TO ALLOW THE PROPAGATION OF RADAR ENERGY INTO THE GROUND %VEN SO  THE LOSS IN PROPAGATING THROUGH TYPICAL SOIL IS SO HIGH THAT THE RANGES OF A SIMPLE MOBILE '02 MIGHT BE ONLY A FEW METERS  3UCH  RANGES ARE SUITABLE FOR LOCATING BURIED POWER LINES AND PIPE LINES  AS WELL AS BURIED  OBJECTS )F A RADAR IS TO SEE TARGETS LOCATED ON THE SURFACE BUT WITHIN FOLIAGE  SIMILAR FREQUENCIES ARE NEEDED AS FOR THE '02 , BAND  TO  '(Z   4HIS IS THE PREFERRED FREQUENCY BAND FOR THE OPERATION  OF LONG 
 282INTRODUCTION TORADAR SYSTEMS facror.Grating lobescausedbyawidelyspacedarraymaytherefore beeliminated with .directive elements whichradiateJinleornoenergy inthedirections oftheundesired lobes.For example, whentheelement spacingd=2,.1"grating lobesoccurat0=±30°and±900in addition tothemainbeamat0=0°.Iftheindividual elements haveabeamwidth somewhat lessthan600,thegratinglobesofthearrayfactorwillbesuppressed. Equation (8.6)isonlyanapproximation, whichmaybeseriously inadequate formany problems ofarraydesign.Itshouldbeusedwithcaution.Itignoresmutualcoupling, andit doesnottakeaccount ofthescattering ordiffraction ofradiation bytheadjacent array elements oroftheoutward-traveling-wave coupling.1214Theseeffectscausetheelement radiation patterntobedifferent whenlocated withinthearrayinthepresence oftheother elements thanwhenisolated infreespace. Inordertoobtainanexactcomputation ofthearrayradiation pattern, thepatternofeach element mustbemeasured inthepresence ofalltheothers.Thearraypatternmaybefoundby summing thecontributions ofeachelement, takingintoaccount theproperamplitude and phase. 
 Ia. Ufimtsev.39'40 (Although these publications may be difficult to find, we cite them here for completeness.) Like Keller, Ufimtsev relied on the (exact) canonical solution of the two-dimensional wedge problem, but he distin- . FIG. 
 POLARIZATION OBSERVATIONS OF AGRICULTURAL VEGETA 
 Rashogi, “Adaptive cancellation of atmospheric  noise and ionospheric clutter for high frequency radar,” MITRE Report, MTR 95B0000112,  September 1995. 136. Y . 
 UNITS  PER KILOMETER  OR AN INCREASE OF   - 
 Ofcourse,onthesmallpageofabookitwouldbeimpossibletoillustrate the coverage of a radar beam to scale with antenna height being in feet andthe lengths of the various lobes of the interference pattern being in miles. Inproviding greater clarity of the presentation of the lobes, non-lineargraduations of the arc of the vertical beam width are used. Figure 1.3 - Radiation diagram. 
 For example, ifland heated bythe sun cools byradiation at night, afairly thin layer ofcold (therefore dense) airmay beformed just above theground, which results inanunusually rapid decrease ofrefrac- tive index with height, the index ofthe lowest layer being abnormally great. Amore widespread cause ofstrong vertical gradients inrefractive index, and therefore ofexcessive bending ofrays, isthe refractive effect ofwater vapor mentioned earlier. Over most ofthesurface oftheocean theregion above the water isnot saturated with water vapor, whereas thelayer directly incontact with thewater must bevery nearly saturated. 
  
 Tech., Pasadena, CA, 1951.  3. S. 
 However, such an assumption applied blindly to computations involving inverse probability  can sonietimes lead to erroneous and contradictory conclusions.29 This difficulty in specifying  the a priori probability was recognized by Woodward and Davies2' They suggest, however,  that the a priori factor be omitted from the inverse-probability specification when it is doubt-  ful, and in practice it may be supplied subjectively by the human observer. This merely begs  the question, for it has not been proved that an operator can supply the necessary a priori  probability, and in addition, there are many applications where no operator is involved in  making the detection decision. Nevertheless, it may be stated that whenever the a priori  probabilities are known, the inverse-probability method may be used with confidence. 
 X7.Bakul.P.A..andI.S.Bol'shakov: ..Questions oftheStatistical TheoryofRadar,vol.II,"chaps10and 11.Sovctskoye Radio.Moscow. 1963.Translation available fromNTIS,AD645775. June28,1966. 
 and G. Brunnis, “Design of a new airport surveillance radar (ASR-9),” Proc.  IEEE , vol. 
 Figure 12.27 illustrates the concept of amplitude compari - son monopulse. A feedback loop minimizes the received difference beam signal by  mechanically steering the antenna to keep the null (and the corresponding sum beam  peak) on target. There are numerous ways to realize amplitude monopulse beams in a reflector  antenna design, but most designs generally fall into two classes; (1) multifeed and  (2) multimode. 
 HUNDREDTH OF THAT CAUSED BY RAIN AND THAT ICE 
 TRACK RESOLUTION 7ITH RESPECT TO 3!2 RESOLUTION  THE PREFERRED TERMS ARE  FINE AND COARSE "ETTER  RESOLUTION IS  FINER  NOT  GREATER POORER RESOLUTION IS  COARSER  NOT  LESS )N THIS WAY  AMBIGUITY IN TERMINOLOGY CAN BE AVOIDED /F COURSE  IN PRACTICE THE TERMS  HIGH 
 101. B. E. 
 5, pp. 71-79,  1958.  49. 
 F. Knott et al., Ref. 14, pp. 
 This allows these targets to be detected. However, for an AEW system operating overland, ground traffic can saturate the tracking sys- tem. Furthermore, traffic density on major highways, target aspect changes caus- ing strong scintillation, and shadowing by cultural features that occurs at low grazing angles can result in misassociation in the target-tracking system, causing false and runaway tracks. 
 ITY AND RELATIVE MAGNETIC PERMEABILITY 4HE VELOCITY OF PROPAGATION OF ELECTROMAGNETIC WAVES IN A SOIL WITH A VALUE FOR  D R OF  WOULD BE SLOWED TO   r  MSn 4HE TIME TO A  TARGET AT A RANGE OF  METER IS  THEREFORE   NS  AND '02 SYSTEMS OPERATE AT TIME RANGES BETWEEN A FEW NANOSECONDS UP TO  NS  ALTHOUGH SOME SYSTEMS FOR PROBING THROUGH  ICE MAY USE RANGES UP TO SEVERAL TENS OF MILLISECONDS )N GENERAL  IT IS NOT POSSIBLE TO MAKE A RELIABLE ESTIMATE OF PROPAGATION VELOCITY OR RELA 
 The sudden surge of current due to a fault in a protected power tube is sensed  and the crowbar switching is actuated within a few microseconds. The current surge also  causes the circuit breaker to open and deenergize the primary source of power. Crowbars are  usually required for high-power, hard-tube modulators because of the large amounts of stored  energy. 
 More recently ascheme ofstagger damping has been proposed. s Before leaving theproblem ofi-famplifier design, some mention ofthe gain required will benecessary. Todetect signals barely visible above thenoise itisnecessary that thenoise originating intheinput circuit and thefirst stage beamplified toapoint where itiseasily visible ontheindi- cator. 
 !  !           !%     !#  !              "        . n°ÎÓ  2!$!2 (!.$"//+  WHERE TD IS THE TIME DELAY OF THE MIDPOINT OF THE SIGNAL MEASURED RELATIVE TO THE MID 
 ¤ ¦¥³ µ´L ;=     WHERE F2K IS THE FIRST BLIND SPEED 02& VELOCITY    &CENTROID IS THE AMPLITUDE 
 Another benefit of  OTHER RADAR TOPICS527 corresponds toacross-range. oralong-track, resolution ofvifj.fd'or J.RJ.R c)=-~.=--=D12cr2117".1 2L~(14.18) whichiswhatwasobtained inEq.(14.6)frqmthesynthetic aperture model.(Intheabove,the relations I'Jd=L.=RA./Dwereemployed.) Rangeresolution. Inmapping orimaging. 
 Note that all of these ambiguity-space trades start with the canonical case. The  trade-offs are relative to that starting position. A radar having an inherently small  range swath, for example, would require ScanSAR to expand the range swath to a few  tens of km, which may still be much larger than the same radar could cover without  ambiguities in a strip-map mode. 
 STATIC RANGE  MONOSTATIC ,/3  AND AN ESTIMATE OF THE BASELINE ! THIRD HITCHHIKING  SITE ALLOWS THE TARGET VELOCITY VECTOR TO BE MEASURED IN THREE DIMENSIONS 4HIS PRO 
 Idealambiguity diagram.Iftherewerenotheoretical restrictions, theidealambiguity diagram wouldconsistofasinglepeakofinfinitesimal thickness attheoriginandbezeroeverywhere else,asshowninFig.11.7.Thesinglespikeeliminates anyambiguities, anditsinfinitesimal. thickriess at the origiri perniits the frequency and the echo delay time to be determined  sirnultarieously to as high a degree of accuracy as desired. It would also permit the resolution  / of two targets no matter how close together they were on the ambiguity diagram. 
 This radiation level is determined from the difference between primary  (feed horn) and secondary (reflector) gains and the leakage (loss) radiation through  the mesh. There are two considerations regarding the reflector surface leakage. The leakage  loss affects the reflector gain directly. 
 A typical tail hemisphere air-to-air ISAR is shown in Figure 5.23.   FIGURE 5.22  Noncooperative target recognition submodes45 ch05.indd   23 12/17/07   1:26:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 UP  AND &- 
 452-466, 1958.  75. Sekhon, R. 
 xii. Acknowledgements I am grateful for the advice and support received from the Defence Electronics History Society (DEHS), particularly Phil Judkins and Mike Dean, and the MalvernRadar and Technical History Society (MRATHS), with Mike Burstow, David Foster and Hugh Williams. The UK National Archives (TNA) at Kew has been an invaluable asset, without which this book would not have been written. 
 of the 1989 IEEE National Radar Conference , Dallas, TX, March 29–30, 1989. 48. J. 
 (a)Pulse hasjustbeen emitted from radar aat. (b)Pulae reaches target. (.)Scattered energy,eturns from target ;transZnittedpul`e carrieO on, (d)Echo pulse reaches radar.. 
 # 
 BASED PASSIVE RADAR v PRESENTED AT !/# TH -ULTINATIONAL 0#2 #ONFERENCE   3YRACUSE  .9  /CTOBER     2 ! 3IMPSON  h3PACECRAFT STUDIES OF PLANETARY SURFACES USING BISTATIC RADAR v  )%%% 4RANS  'EOSCIENCE AND 2EMOTE 3ENSING  VOL  NO   -ARCH . ÓÎ°Î{  2!$!2 (!.$"//+   $ 0RICHARD   4HE 2ADAR 7AR 4HE 'ERMAN !CHIEVEMENT  n   #AMBRIDGE  5+ 0ATRICK  3TEPHENS ,TD    ! 0RICE   )NSTRUMENTS OF $ARKNESS 4HE (ISTORY OF %LECTRONIC 7ARFARE   .EW 9ORK #HARLES  3CRIBNERS 3ONS    0 * +LASS  h.AVY IMPROVES ACCURACY  DETECTION RANGE v  !VIATION 7EEK AND 3PACE 4ECHNOLOGY    PP n  !UGUST     4ECHNOLOGY IN THE .ATIONAL )NTEREST  ,EXINGTON  -! -)4 ,INCOLN ,ABORATORY    ! "ERNARD  PRIVATE COMMUNICATION  -)4 ,INCOLN ,ABORATORY  *ULY     3 3ATOH AND * 7URMAN  h!CCURACY OF WIND FIELDS OBSERVED BY A BISTATIC DOPPLER RADAR NETWORK v  *OURNAL /CEAN !TMOS 4ECH  VOL   PP n    ! % 2UVIN AND , 7EINBERG  h$IGITAL MULTIPLE BEAMFORMING TECHNIQUES FOR RADARS v IN  )%%%  %ASCON  2EC  PP n  % % 3WARTZLANDER AND * - -C+AY  h! DIGITAL BEAMFORMING PROCESSOR v  2EAL 4IME 3IGNAL  0ROCESSING )))  30)% 0ROC  VOL   PP n    ! &ARINA  h4RACKING FUNCTION IN BISTATIC AND MULTISTATIC RADAR SYSTEMS v  0ROC )%%  VOL     PT &  PP n  $ECEMBER   2 " 0ATTON  *R  h/RBIT DETERMINATION FROM SINGLE PASS DOPPLER OBSERVATIONS v  )2% 4RANSACTIONS  ON -ILITARY %LECTRONICS  PP n  !PRILn*ULY    ! &ARINA  h4RACKING FUNCTION IN BISTATIC AND MULTISTATIC RADAR SYSTEMS v  )%% 0ROC       PT &  PP n  $ECEMBER   - ) 3KOLNIK  )NTRODUCTION TO 2ADAR 3YSTEMS  .EW 9ORK -C'RAW (ILL "OOK #O   $ + "ARTON  2ADAR 3YSTEM !NALYSIS  $EDHAM  -! !RTECH (OUSE  )NC   + - 3IEGEL  ET AL  h"ISTATIC RADAR CROSS SECTIONS OF SURFACES OF REVOLUTION v  * !PPL 0HYS   VOL   PP n  -ARCH   + - 3IEGEL  h"ISTATIC RADARS AND FORWARD SCATTERING v IN  0ROC .AT #ONF !ERONAUT %LECTRON    -AY n    PP n  & 6 3CHULTZ ET AL  h-EASUREMENT OF THE RADAR CROSS 
 The feed -ins of antennas of this type are created by 6x λ/4 Hybrids (rat race ring) or “Magic  Tee’s” (Figure 13.3).  3 2 4 1ZLZLZLZL ZL2 λ 4λ 4λ 4 3λ 4input transmit beam 1beam 2 beam 1 beam 2 input transmit1 234     Figure 13.3  Transmit feeds of a mono pulse antenna for the ψ−plane (equivalent θ−plane).   Left: 6x λ/4 Hybrid. 
 In the iteration of LS-CS-Residual, the azimuth-range decoupled operators are used to avoid the huge memory cost. Real data processing results show that LS-CS-Residual can estimate the aspect dependent scatterings of the targets more accurately than CS based methods. Keywords: wide angle SAR; compressed sensing; LS-CS-Residual; aspect dependent 1. 
 (In the above, an impulse is an infinitesimally short pulse, and the target  response is the echo signal as a function of time.) This has been proposed as a means of target  clas~ification,~~ with the impulse being approximated by a short microwave pulse. The short  pulse, with its high-frequency content, characterizes the finerdetail of the target. Although this  can be used as a means of target classification, it has been suggested that the usual short-pulse  radar does not obtain important information about the target since its waveform does not  contain the lower frequencie~.~~-~~*~~ The lower frequencies that are suggested as being im-  portant are those corresponding to wavelengths from half the target size to wavelengths about  EXTRACTION OFINFORMATION ANDWAVEFORM DESIGN437 Nonlinear-<:ontact effects(METRRA).48 Whenmetalscomeincontactwitheachotheritis possible fortheirjunctions toact-asnonlinear ,diodes.Thenonlinear properties ofsuch junctions canbeusedtorecognize metallic fromnonmetallic reflectors whenilluminated by radar.Thistechnique hassometimes beencalledMETRRA, whichstandsforMetalReradiat­ ingRadar.48Mostsolid,mechanical, metal-to-metal bondsandproperly madesolderjoints donotshownonlinear errects.However, ifthereisnomolecular contactbetween themetals, andthespacebetween themissmall(oftheorderof100A),thentherecanbediscernible nonlinear effects.Sucheffectsarenotedwithloosemetal-to-metal contacts. 
 FICIENT AND THE TOPOGRAPHY WHEN INTERPRETING ECHOES FROM TARGETS ABOVE THE GROUND 3EA #LUTTER  )N CONTRAST WITH THE ABRUPT CHANGES IN SCATTERING BEHAVIOR THAT  OCCUR AT COASTLINES OR OVER COMPLEX TERRAIN  THE MAGNITUDE OF THE RADAR ECHO FROM  THE OPEN OCEAN  THAT IS  THE SCATTERING COEFFICIENT  R n TENDS TO VARY SLOWLY WITH RANGE  AND AZIMUTH AS A CONSEQUENCE OF THE SCALE LENGTHS OF TYPICAL OCEANIC METEOROLOGICAL  SYSTEMS AND THE RESPONSE TIME OF THE OCEAN SURFACE TO VARYING WIND STRESS -OREOVER  MUCH OF THE TIME  TO A REASONABLE APPROXIMATION  THE ECHO POWER IS PROPORTIONAL    TO THE RESOLUTION CELL AREA AND CAN BE USED AS AN ABSOLUTE AMPLITUDE REFERENCE WHEN CARE IS EXERCISED 4HE REASON FOR THIS IS EXPLAINED LATER IN THE DISCUSSION OF    RADAR OCEANOGRAPHY /F FAR GREATER INTEREST THAN THE AVERAGE MAGNITUDE OF THE SEA ECHO IS THE WEALTH  OF INFORMATION EMBEDDED IN ITS DOPPLER SPECTRUM  4HE WAVES ON THE SEA SURFACE  INTRODUCE A COMPLEX MODULATION ON THE REFLECTED RADAR SIGNAL  WHICH IS MANIFESTED IN THE SIGNALS DOPPLER SPECTRUM %STIMATION AND INTERPRETATION OF THIS MODULATION YIELDS INFORMATION ON THE TIME 
 Rec., vol. 7, pt 5,  pp. 67-73. 
 Figure 16.32 shows this.12 The effect can be many decibels (9 dB in the figure). Vegetation canopies over soil can contribute to scatter in the various ways shown  in Figure 16.33.135 Figure 16.3443 shows an example. Most of the scatter from  the entire plant came from the top leaves, with enough attenuation there to reduce   ch16.indd   35 12/19/07   4:56:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 FREQUENCYv PULSE  WE MEAN A PULSE CONSISTING OF A PURE SINUSOIDAL TONE MULTIPLIED BY A RECTANGULAR FUNCTION OF DURATION hWIDTHv   S MUCH LONGER THAN THE PERIOD OF THE TONE 3UCH A  PULSE IS NOT TRULY SINGLE 
 Deviations from the ideal characteristics can degrade radar  performance in a variety of ways. Linearity Below Limiting.  One major drawback of adding a limiter stage to a  receiver channel is that it is inherently nonlinear. 
 There are several methods for generating phase shift that utilize the properties or circular  polarization. One or the first devices to employ circularly polarized waves propagating in  round waveguide was the Fox phase shirter.39 This rotary-waveguide phase shifter was applied  in World War II by the Bell Telephone Laboratories in the FH MUSA, or Mk 8, scanning . 298 INTRODUCTION TO RADAR SYSTEMS  radar.4·59 This was the first US radar to use a phased-array antenna with phase shifters to steer  the beam. 
 (1 1.29)) as the trapezoidal pulse  becomes more rectangular, that is, when TI = 212 % T2.  For the triangular pulse, we set TI = 0 in Eq. (1 1.3 1) and let 2T2 = T,. 
 (Based on C-band measurements by Pidgeon.51) The details of the clutter spectrum show little dependence on either the radar frequency or the grazing angle, at least for angles less than about 10°. In review- ing the results of measurements at four frequencies—UHF, L, C, and X bands— Valenzuela and Laing50 noted a relatively weak tendency of clutter bandwidth to decrease with increases in frequency between the UHF and X bands and grazing angles between 5 and 30°. Since both of these variations entail a decrease in the size of the radar footprint on the surface, they might be due to a dependence on resolution cell dimensions, although the other workers found that the pulse length had little effect on clutter bandwidth for values between about 0.25 and 10 JJLS. 
 12.3 assume a smooth  reflecting surface. In practice, this condition is seldom met, and the difference in the coverage  diagrams obtained with each of the two types of polarization is often not as pronounced as  might be expected on the basis of theoretical computations. Roughness is more important than  the electrical properties in determining whether reflection is specular or not. 
 KM SWATH  WHICH IS NARROWER THAN THAT OF 3EASAT * 
 (ILL    * - (UDNALL AND 3 7 $ER  h(& 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 23.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 Target location is established by triangulation, i.e., the intersection of zenith angle  (DOA) measurements from two or more receive sites. 
 The performance charac- teristics oftunable magnetrons m-eequivalent tothose ofthecorrespond- ingfixed-frequency tubes, and there isthus noreason, except availability, fornotusing them. Tuning ofthe higher-frequency microwave magnetrons isaccomp- lished byinserting conducting cylinders into the’ inductive portion of each resonant cavity, thus decreasing the effective inductance. This construction, sho}vn inPig. 
 Phase accuracy, or sta- bility, requirements are the same as those for coherent processing by a monostatic radar: from 0.01X to O.IX, or 3.6° to 36° of RF phase over a coher- ent processing interval,133 with 0.01X representing more typical design re- quirements. Direct phase locking can be implemented as in direct time synchronization: via landline, communication link, or at the transmitter's RF. If a direct RF link is used, adequate transmitter-to-receiver LOS is again required. 
 Appl. Meteorol. ,  vol. 
 The idea of pouring oil on troubled waters is a familiar one: the angry surface will smooth and subside. In another age, the survival- gear locker of every sailing ship would contain a bottle of oil to quiet the sea in a storm. Although the effectiveness of this procedure has always been somewhat controversial, there is no question that oil can produce a slick of smooth water at relatively low wind speeds. 
 H.: The Design of Hybrid Multiple Beam Forming Networks, " Phased Array Antennas,"  A. A. Oliner and G. 
 TIVELY LOADED DIPOLE ELEMENT DUE TO AN APPLIED IMPULSE   #OURTESY )%%  .   '2/5.$ 0%.%42!4).' 2!$!2   Ó£°ÓÇ IN WHICH HIGH FREQUENCIES ARE RADIATED FIRST  FOLLOWED BY THE LOW FREQUENCIES ! hSPIK 
 PATTERN SIDELOBES 4HE MULTIPATH ERRORS THAT RESULT ARE CYCLIC  ALMOST SINUSOIDAL  WITH AN RMS VALUE PRE 
 GAIN AUXILIARY THAT IS USED FOR 3," PROCESSING IN THE MAIN CHANNEL 4HE ADAPTIVE CANCELLATION OF .,) RECEIVED BY THE MAIN ANTENNA IS ACHIEVED BY THE LINEAR COMBINATION OF THE  3,# AND  -!). SIGNALS WITH THE ADAPTIVE  WEIGHTS 7  AND   RESPECTIVELY THE RESULTING ADAPTED SIGNAL  -!).g DOESNT CONTAIN THE  .,) 3IMILARLY  THE ADAPTIVE CANCELLATION OF .,) RECEIVED BY THE RHS AUXILIARY ANTENNA IS REACHED BY THE LINEAR COMBINATION OF THE  3,# AND  3," SIGNALS WITH THE ADAPTIVE  WEIGHTS 7  AND   RESPECTIVELY THE ADAPTED SIGNAL  3,"g DOESNT CONTAIN THE .,) /NCE  THE .,) IS REMOVED FROM THE TWO CHANNELS  THEN THE CLASSIC 3," LOGIC CAN BE APPLIED AGAINST THE #2) BY COMPARING THE AMPLITUDE \ -!).g\ OF THE MAIN CHANNEL WITH THAT  \3,"g\ OF THE BLANKING CHANNEL  WHICH ARE BOTH .,) FREE  "ECAUSE THE PHASE CENTERS OF THE THREE ANTENNAS THE MAIN AND THE TWO AUXILIARIES   ARE SPACED  IN GENERAL  MORE THAN   K WHERE  K IS THE LENGTH OF THE RADIATED %-  WAVE   THE ADAPTED PATTERNS OF THE MAIN AND 3," CHANNELS FLUCTUATE AROUND AVERAGE CURVES DUE TO THE PRESENCE OF GRATING LOBES  .EVERTHELESS  A REASONABLE GAIN MARGIN  IS PRESENT BETWEEN THE PATTERN OF THE ADAPTED 3," AND THE SIDELOBES OF THE ADAPTED MAIN ANTENNA THUS  AN ADEQUATE PROBABILITY OF BLANKING THE #2) IN THE PRESENCE OF ADAPTIVELY NULLED .,) SHOULD BE EXPECTED )N ORDER TO IMPROVE THE ABOVE GAIN MARGIN AND  CONSEQUENTLY  THE BLANKING PROBABILITY OF #2)  THE FOLLOWING PROCESSING STRATEGIES ARE SUGGESTED   SPATIAL AND FREQUENCY DIVERSITY 3PATIAL $IVERSITY  4HE RATIONALE IS TO USE TWO LOW 
 12.2] ATYPICAL RECEIVING SYSTEM 437 itexperiences anamplification ofsome 120db. Following thei-fampli- fier isa“second” detector and i-ffilter which rectify the signals and remove thei-fcomponents, leaving only thevideo signal envelope. The signal channel iscompleted byavideo amplifier which delivers the signal atproper voltage level totheinput terminal ofthe CRT orother indicator. 
 The answer to what  is provided by typical waveform variations  and a few examples. The examples are not from any single radar but are a composite  of modern radars. The general MFAR idea is illustrated in Figure 5.2. 
 lar resolution the 3D radar provides a higher-gain antenna and, arguably, a greater resistance to jamming and other forms of electronic countermeasures (ECM) than a combination of 2D and dedicated height finder. The counterargument points out that the 2D and height finder may be implemented in two separate frequency bands, forc- ing the jammer to spread out its energy, thereby diluting it. Rotating 3D radars can be implemented as stacked-beam radars, frequency- scanned radars, phase-scanned radars, electromechanically scanned radars, and digital beamforming radars, according to how the elevation beams are formed and/or scanned in elevation. 
 A single-stage  Class-C biased BJT amplifier will typically exhibit a very narrow “linear” transfer  characteristic; the linear region may exist over only a narrow 1- to 3-dB window of  RF input drive. This becomes strikingly critical when several Class-C-biased stages  are cascaded in series, as is common in most amplifier configurations. The final tier  of output transistors in a serial amplifier chain must be driven into saturation by the  preceding stages, and the drive level must be held relatively constant as a function  of time and temperature. 
 I3uncan. and M, B. Laing: NKL Terrain Clutter Study. 
 CHAPTER 14 PRIME POWER SUPPLIES FOR RADAR BY M. M. HUBBARD AND P.C.JACOBS Radar equipment requires foritsoperation high-voltage (1000- to 10,000-volt) direct current, medium voltage (~00- to600-volt) direct current, and power forvacuum-tube heaters which usually can beeither alternating ordirect current. 
 Inthis way the swamping ofbeacon replies bystrong echoes iseliminated. Even when itisdesirable that radar echoes and beacon replies bepresented simultaneously, the saturation video levels forthe two kinds ofsignals canbemade different byusing separate receivers; thus beacon replies can bemade tostand outeven when superimposed onsaturated ground clutter. Avery striking differentiation between radar and beacon signals from aircraft has been achieved byputting them onseparate PPI tubes that give signals intwo different colors, the signals being effectively super- imposed byoptical means. 
 A circulator at the module output port is commonly used to protect the amplifier from the damaging effects of high-load VSWR, most notably from the antenna. Also, ancillary circuitry such as energy storage capacitance, built-in-test (BIT) sensors, or adaptive control components may be included.10 Single-stage Characteristics. Transistors that operate in the HF through S- band frequency ranges are commonly biased either Class-B or Class-C. 
 FORMED WITHIN THE DIGITAL SIGNAL PROCESSOR  USING SAMPLES SEPARATED AT THE 02& RATE 4HE RESULTING SAMPLING OF THE RECEIVER OUTPUT AT THE 02& PRODUCES ALIASING OF THE PHASE NOISE SPECTRUM PERIODICALLY AT THE 02& INTERVAL  AS SHOWN IN &IGURE   WHERE EACH CURVE REPRESENTS THE PHASE NOISE AT THE OUTPUT OF THE RECEIVER  INCLUDING THE EFFECTS OF RECEIVER FILTERING AND OFFSET BY A MULTIPLE OF THE 02& FREQUENCY 4HE COMBINED  PHASE NOISE DUE TO EACH ALIASED COMPONENT IS CALCULATED USING %Q  WITH THE RESULT  ILLUSTRATED IN &IGURE  4HIS SAMPLED PHASE NOISE SPECTRUM PROVIDES A METHOD FOR COMPARING DIFFERENT ,/ PHASE NOISE PROFILES AND THEIR RELATIVE IMPACT ON THE OVERALL PERFORMANCE OF THE SYSTEM  }     \   \, F , F KF ( F KF K `  §©¶¸ 
  
 U.S.A.F. Camhridge Researclt Cellter Geophys.  Research Papers, no. 
 PARAMETER 7EIBULL DISTRIBUTIONS DEFINED BY DIFFERENT PARAMETER PAIRS )T IS CLEAR THAT THE BEHAVIOR IS DIFFERENT AND CONSIDERABLY MORE COM 
 Gierull, F. Gini, and U. Nickel (eds.), Special Issue “New trends and find - ings in antenna array processing,” Signal Processing , Elsevier, vol. 
 Instead, the phase shifters or a single feed provide the azimuth steering while the M feeds at  each column provide the elevation steering. In the series-series planar array all series phase  shifters in the elevation plane take the same value and all series phase shifters in the azimuth  plane take the same value. Thus only two control signals are required. 
 circuits of this radar. Thus the apparent extended clutter has many weak areas not visible in these photographs, where targets could be detected by virtue of an MTI radar's interclutter visibility (defined in Sec. 15.4). 
 However, thesimplerreceiver isnotassensitive becauseofincreased noiseatthelower intermediate frequencies causedbyflickereffect.Flicker-effect noiseoccursinsemiconductor devicessuchasdiodeqetectors'and cathodes ofvacuumtubes.Thenoisepowerproduced by theflickereffectvariesas-liP',whereIdsapproximately unity.Thisisincontrasttoshotnoise orthermalnoise,whichisindependent offrequency. Thus,atthelowerrangeoffrequencies (audioorvideoregion),'w'herethedoppler frequencies usuallyarefound,thedetector ofthe CWreceivercanintrOduce aconsiderable amount'offlickernoise,resulting inreducedreceiver sensitivity. Forshort-range,. 
 The cylinder, which is probably the simplest form of nonplanar array, has a geometry  suitable for antennas that scan 360" in azimuth. The scanning beam of a cylindrical anienna  does not change its shape and broaden when steered, as does a scanning beam from a planar  array. Beam steering in a circularly symmetric array can be accommodated by comniutating  or rotating the aperture distribution. 
 For reference, the mean of I3 is also shown for linear processing. ( I3 refers to the  improvement factor of a three-pulse MTI canceler.) ( after T. M. 
 The ratio a is defined as a number less than unity. The angular error A0 as  measured from the larger of the two targets is3'  A0 -- - a2 + a cos or  OD 1 + a2 + 2a cos or  This is plotted in Fig. 5.13. 
 M LONG ELEMENTS WERE  NOT UNFURLED UNTIL TWO YEARS INTO THE MISSION  DUE TO CONCERNS ABOUT THEIR POTENTIAL FOR DAMAGING THE SPACECRAFT DURING DEPLOYMENT 4HE EFFECTIVE CROSS 
 DIMENSIONAL WEDGE PROBLEM  FOR WHICH THE DIRECTIONS  OF INCIDENCE AND SCATTERING ARE PERPENDICULAR TO THE EDGE 7HEN EXTENDED TO THE CASE  OF OBLIQUE INCIDENCE  THE DIRECTION OF OBSERVATION MUST LIE ALONG A GENERATOR OF THE +ELLER CONE DEPICTED IN &IGURE  )F THE EDGE IS STRAIGHT AND OF FINITE LENGTH  AS IN THE THREE 
 5.Electronic inverters. Low-voltage d-c input, output asdesired. The options (2)and (5)can bediscarded atonce. 
 R. J. Keeler and C. 
 Searching avolume inspaceforanaircraft targetwithanarrow pencilbeamwouldbe somewhat analogous tosearching foraflyinadarkened auditorium withaflashlight. Itmust hedonewithsomecareiftheentirevolume istobecovered uniformly andefficiently. Examples ofthecommon typesofscanning patterns employed withpencil-beam antennas are illustrated inFig.5.18. 
 It is evident that the ship lengths extracted from the proposed method results are smaller than other results in Figure 9a. The widths and areas of proposed method results are also the least of the four results in Figure 9b,c. These results indicate that the refocusing result of the proposed method is better than that of the other methods. 
 Through the above steps, the DEM data with coordinate ( θi,Rs j) on the slant range are transformed to the ground range. The coordinate of these DEM data on the ground range is ( θi,Rge(j)). The above steps only describe the process of transforming one DEM datum in the DEM image from the slant range to ground range. 
 ANGLE OGIVE RECORDED FOR HORI 
 #LOSE OBSERVATION OF THE SEA SURFACE DISCLOSES A VARIETY OF FEATURES DESCRIBABLE AS  WEDGES  CUSPS  WAVES  FOAM  TURBULENCE  AND SPRAY  AS WELL AS BREAKING EVENTS OF ALL SIZES AND MASSES OF FALLING WATER !NY OR ALL OF THESE MIGHT CONTRIBUTE TO THE SCATTER 
 The K1 tidal alias is very nearly two  cycles per year, thus appearing close to geophysical signals associated with seasonal  effects. K1 cannot be ignored, as it is the largest diurnal constituent and is second in  magnitude only to the dominant lunar constituent. The constraint on the exactness of an orbit’s repeating ground track is determined to  first order by the fine structure in the local geoid expressed at the ocean’s surface.75 For  example, cross-track surface slopes (gradients) in the geoid may be as large as 2 × 10–4  near the deeper oceanic trenches. 
 (25), that ndoes nothave tobelarger than 120pulses perbeamwidth. Again, from Eq. (24), therms wind fluctuation should beless than 22db. 
 POINT  SPECTRAL MULTIPLICATION  OPERATIONS THAT  RELATE THOSE SIGNALS 4HE FIRST LINE IN THE FIGURE DEPICTS SCHEMATICALLY A REAL )& SIGNAL WITH ONE 
   3%! #,544%2  £x°Óx BEYOND THE CONVENTIONAL OPTICAL HORIZON  SUCH PERTURBATIONS COULD PRODUCE STRONG  FOCUS 
 l, p. 114, John  Wiley & Sons, Inc., New York, 1957.  30. 
 ... ... .. 
 The first major electronically  scanned phased arrays that perforrned beam steering without frequency scan employed the  f luggins pilase shifter (Sec. 8.4) which. in a sense, used the principle of frequency scan without  tlie necessity of ctiarigi~lg the radiated frequerlcy. 
 This is often useful  in coupling the last stage of a  radar circuit to a CRT.  ‘Gating’ circuits are com-  monly used in radar equip-  ment, and a typical circuit is  shown in Fig. 17. 
 For the samcfsize aperture, the beamwidth of a conical-scan  radar will be slightly greater than that of the monopulse because its feed is offset rrom the  focus.  The tracking accuracy of a monopulse radar is superior to that of the conical-scan radar  because of the absence or target amplitude-fluctuations and because or its greater signal-to­ noise ratio. It is the preferred technique for precision tracking. 
 E. West, “Accurate radar attenuation measurements achieved by  inflight calibration,” IEEE Trans. , vol. 
 (/2):/. 2!$!2   Óä°Îx OR EQUIVALENTLY  IN TERMS OF WAVE FREQUENCY   &G G UE  E X PVA V V 
 W .. and A. M. 
  $ 
  MATCHED POLARIZATION R    MMH G  M n   r n r n r n r n  &ROM "ARTON. Ó°£n  2!$!2 (!.$"//+  "ECAUSE OF THE IMPRECISION IN PREDICTING  R  AND G  THESE EQUATIONS DO NOT INCLUDE  AN ANTENNA BEAM 
 DELAY COHERENT CANCELER  ) IS THE -4) IMPROVE 
 The cathode feedback ofthe final arriplifiers issufficient togive reasonably linear current amplification, since thepush-pull action tends tocompensate fortube nonlinearities. The high-frequency response is notgood enough, however, toprovide alinear displacement atthebegin- ning ofvery fast sweeps. For this reason a“step” isintroduced atthe beginning ofthe sawtooth byplacing asmall resistor inseries with the charging condenser ofthe sawtooth generator. 
  WAS REPHASED TO A LONG REPEAT PERIOD  DAYS  4HAT LONG REPEAT PERIOD GENERATED A RELATIVELY DENSE SURFACE SAMPLING GRID USEFUL FOR ESTIMATING SEA ICE COVER  GEODESY  AND BATHYMETRY 4HE %23 
 Keep in mind that this may result in greater Doppler sens itivity. Re -consider  the required digital filter transie nt response.  Determine required A/D converter sampling rate. 
 LINE  IE  LOCATED BETWEEN RECEIVER AND TRANSMITTER WHERE THE BISTATIC ANGLE  A l    A COMPLETELY DIFFERENT ENVIRONMENT IS GENERATED  FORWARD SCATTER FROM BOTH TARGET AND  CLUTTER )N THIS CASE  THE TARGET RADAR CROSS SECTION 2#3  AND CLUTTER SCATTERING COEF 
 These calculations show that the attenuation in the melting of ice imme - diately under the 0 °C isotherm can be substantially greater than in the snow region just  above and, under some circumstances, greater than in the rain below the melting level.  Further melting cannot lead to much further enhancement, apparently, and may lead to a  lessening of the reflectivity of the particle by bringing it to sphericity or by breaking up  the particle. Melting of ice particles produces enhanced backscatter, and this effect gives  rise to the observed elevated bright band 53 near the 0 °C isotherm. 
 MANCE AND TO BETTER INTEGRATE A RADARS SPATIAL PROCESSING ANTENNA SIDELOBE CONTROL AND  SIDELOBE JAMMING CANCELLATION  WITH ITS TEMPORAL CLUTTER CANCELLATION PROCESSING 4HE APPLICABILITY OF 34!0 TO IMPROVING CLUTTER CANCELLATION MUST BE ASSESSED SPE 
 It means that, with the measurement matrix, the memory cost is reduced fromO(n2)toO(n). 32. Sensors 2019 ,19, 490 BP mainly includes two operations: range Fourier transform and azimuth coherent addition. 
 A different typs  of blind-bombing device was needed, which would bs  relatively immune from enemy jamming and whict  would be self-contained in the aircraft, demanding n  co-operation from ground stations. The success of air:  borne radar in fighters over home territory in wardin;  off the threatened attacks of enemy bombers and nigh  fighters led T.R.E. technicians to explore other possi  bilities of such airborne radar. 
 FREQUENCY 
 He also found some evidence in support of the radar operators, at least for the low grazing angles and horizontal polar- izations with which most shipboard radars operate. Figure 13.16 compares the correlation function of sea clutter (X band, low grazing angle, H polarization) with and without rain for a 15-kn wind speed and a rain rate of 4 mm/h. The sharp decrease in correlation time in the presence of rain reflects the broadening of the clutter spectrum. 
 When the values of ac for scanning modulation [Eq. (15.5)] are substituted in the above equations for 7, the limitation on / due to scanning is ''-I39 (15'12) . /z~ ^4 (15'13) /J- l£5 (15'14) These relationships are shown graphically in Fig. 
 WIDTH DISCRIMINATOR  THIS LATTER BEING EFFECTIVE  AGAINST PULSED JAMMERS 4HE PULSE 
 This  function can be obtained with a more sophisticated filter consisting of a parallel combination  of integrator and subtra~tor.~~ The integrator is a narrow-band filter that averages the order of  ten range-resolution cells to establish the background level. A receiver implemented in this  manner has been called a log-CFAR.iThe term LOGICFAR has been applied to the cell-  averaging CFAR which* is precedediby a logarithmic detector.84 The normalization of the  threshold is accomplished in thclCOG/CFAR by subtraction rather than by division as in the  conventional cell-averaging CFAR.' Also, the LOGICFAR is capable of operating over a larger  dynamic range of background noise levels, but it has poorer detectability forthe same number  of reference noise samples than the conventional cell-averaging CFAR.  394INTRODUCTION TORADAR SYSTEMS rankdetector whichcomputes theranksbypair-wise comparisons oftheQutputfromtherange cellundertestwitheachoftheoutpl,ltsfromtheneighboring rangecellsthatsamplethe background noise.78-81Afterthedetector ranksthesampleundertestwithitsneighboring samples, itintegrates theranksandatargetisdeclared aftertestingagainstafixedandan adaptive threshold.8o,81 Thereareseveralothermethods forachieving CFARbesidestheuseofcellaveraging. 
 it is assumed that the signal is large compared with the noise. This is a  reasonable assumption since the signal-to-noise ratio must be relatively large if the detection  decision is to be reliable (Sec. 2.5). 
 Theabovevaluesapplytoaparticular experiment inaparticular location. Hence.theoptimum antenna heightsmightvary. Theoretical modelsofpropagation inevaporation ductsconfirm thegenaalexperimental ohservations presented above.77Whenmultiple modesofpropagation an;trapped intheduct. 
 Thorp. J. S.: Ortimal Tracking of Maneuvering Targets, IEEE Trans .• vol. 
 TION OF THE DIRECTION COSINE COORDINATE SYSTEM )N THIS SYSTEM  THE LINEAR 
 The prf may be changed continuously within  prescribed limits, or it may be changed discretely among several predetermined values. The  number of separate pulse repetition frequencies will depend upon the degree of the multiple-  time targets. Second-time targets need only two separate repetition frequencies in order to be  resolved. 
 SYMMETRICAL REFLECTOR  M BY  M  WITH TEN FEEDS  OFFSET FROM THE FOCAL POINT SO THAT THE BEAM CAN BE ELECTRONICALLY SCANNED IN ELEVATION 3PATIAL RESOLU 
 Itsrmsrangeerroris r l.l8 ~IR=1.l8(iEIN~)ii2 =~B(2ElN~p12gaussian pulse (11.25) whereHisthehalf-power bandwidth ofthegaussian-pulse speclrum. Thecrrective bandwidth ofawaveform withauniform frequency spectrum ofwidthBis {i=rrBlj!.. Thewaveform whichgivesrisetoauniform frequency spectrum isoftheform (sillx)/x.wherex=rrIJr.Therrnstime-delay erroristherefore . 
 F. Earl, “Receiving system linearity requirements for HF radar,” IEEE Trans. Instrum. 
 The intensity (or illumina nce or irradiance) of linear waves  radiating from source (energy per unit of area perpendicular to  the source) is inversely proportional to the square of the  distance from the source as shown in Figure 18. An area of  surface A1 (as of the same size as an a rea of surface A2) twice  as far away, receives only a quarter of the energy SA1. The  same is true for both directions: for the transmitted, and the  reflected signal. 
 The condition forbalance ofthe two links, namely that R:equal R:,then becomes (4) The receiver ofthebeacon isalmost always less sensitive than that ofthe radar, either bynecessity (because ofthe greater bandwidth), orby choice toavoid undesired triggering (see below); hence P:,<P~i.In the balanced system, then, thetransmitter ofthebeacon may aswell be less powerful than that ofthe radar inthe same proportion. Inactual cases, Eq. (1)and acorresponding equation forthereceived power inthe reply link involve two additional factors. 
 SISTS OF DISCRETE LINES AT THE CARRIER FREQUENCY  F  AND AT SIDEBAND FREQUENCIES  F o IF2  WHERE  F2 IS THE 02& AND  I IS AN INTEGER 4HE ENVELOPE OF THE SPECTRUM IS DETERMINED BY THE PULSE  SHAPE &OR THE RECTANGULAR PULSES USUALLY EMPLOYED  A SIN X X SPECTRUM IS OBTAINED 5SING A CONSTANT 
 [ CrossRef ] 26. Martorella, M.; Giusti, E.; Berizzi, F.; Bacci, A.; Mese, E.D. ISAR based technique for refocusing non-cooperative targets in SAR images. 
 REFLECTING OBJECTS   SUCH AS BUILDINGS  AND SO NEEDS TO BE LOCATED IDEALLY IN RELATIVELY OPEN SPACES  SIMILAR TO THAT FOUND ON AN ANTENNA FAR 
 Bur. Standards (U.S.) Cin:.  557, Aug. 
 8.4a has the same value of  phase shift, only a single control signal is needed to steer the beam. The N-element parallel-fed  linear array similar to that of Fig. 8.2 requires a separate control signal for each phase shifter  or N -1 total ( one phase shifter is always zero). 
 OF 
 80. Rahincr. L. 
 17”5a), initiates theaction ofatime-delay circuit consisting ofasawtooth generator V%,abiased diode V&,an amplifier V*,and ablocking oscillator V4b. The need forasquare-wave. 694 RADAR RELAY [SEC. 
 Reduced microwave losses and other features were also expectedto further improve the range performance. The increased power would also increase the range at which the U-boat warning receivers would detect the radar, which was potentially disadvantageous. However, if there were suf ﬁcient aircraft in a search area it was postulated that U-boats could not afford to submerge at every long-range detection, but would only do so if the received signal power was increasing,consistent with an approaching aircraft. 
 The beat frequency generated bythe crystal isthen amplified byVgand applied tothe discriminator detector. The dis- criminator output signal, intheform ofavideo pulse, isamplified byVII before being applied tothe control tube. 12.10. 
 Proc. SPIE 2008 ,6970 .[CrossRef ] 7. Cong, X.; Guan, G.; Yong, J.; Li, X.; Wen, G.; Huang, X.; Qun, W. 
 SENSITIVE CHARACTERISTIC IS TO PROVIDE A PLUS OR MINUS POLARITY COR 
 The first network is the mixer with noise figure t, LC and  gain = IJL,. The second network is the IF amplifier with a noise figure F1,. The receiver  noise-figure with a mixer front-end is then  (This does not include losses in the RF transmission line connecting the rweiver to the  antenna.)If, for example, the conversion loss of the mixer were 6.0 dB, the IF noise figure 1.5 dB,  and the noise-temperature ratio 1.4, the receiver noise figure would be 8.6 dB. 
 PHASED ARRAY RADAR ANTENNAS  13.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 relative phase setting.22 Other methods have been proposed23 where measurements  are compared with previously recorded ones. Deployment of Apertures.  With planar arrays, scanning is limited by the loss in  gain and the increase in beamwidth corresponding to the reduction of the aperture to  its projected area. 
 10.15. Pair 4. The frequency-weighting function includes a Fourier series of n — 1 cosine terms, where the selection of n is determined by the required compressed pulse width and the desired sidelobe falloff. 
 V., R. C. Burgener, and S. 
 N-scope. A K-scope having an adjustable pedestal signa~ as in the M-scope, for the measurement of  distance.  0-scope. 
 NUMBER OF PULSES FIG. 2.5 Required signal-to-noise ratio (detectability factor) as a func- tion of number of pulses noncoherently integrated, linear detector, nonfluctuating target, and 0.9 probability of detection. (From Ref. 
 FIELD CALIBRATION IS PERFORMED AT REGU 
  6(&5(&     -ODERATEn(IGH 4!$), 5(& 
 The circumference of the chart corresponds to infinite VSWR, or unity reflection  coefficient. Thus the region of low standing-wave ratio is toward the center of the chart. 30 600,------,------,------..,,--- 25 500 - ~ > 20 '::: 400  ·" ::, - 0. 
 DELAY CONFIGURATIONS A  TIME DELAY BY CHOOSING UPPER OR LOWER PATHS AND  B  TIME  DELAY BY USING SWITCHED CIRCULATORS . £Î°{È  2!$!2 (!.$"//+  £Î°nÊ  
 Control of the cross-correlation sidelobes is vital to  achieve good range resolution and the sidelobes are affected by the antenna and system  characteristics as well as the duration and randomness of the transmitted waveform.  Further information is given by Narayanan24 and Sachs et al.25,26 21.7 ANTENNAS In the ultrawideband case, the radar antennas are considered in terms of their transfer  function rather than their gains or effective apertures. In many cases, a separate transmit  and receive antenna is used; hence their transfer functions may not be identical. 
 viii CONTENTS  11.5 Pulse Compression 420  11.6 Classification of Targets with Radar 434  References 438  12 Propagation of Radar Waves 441  12.1 Introduction 441  12.2 Propagation over a Plane Earth 442  12.3 The Round Earth 446  12.4 Refraction 447  12.5 Anomalous Propagation 450  12.6 Diffraction 456  12.7 Attenuation by Atmospheric Gases 459  12.8 Environmental Noise 461  12.9 Microwave-Radiation Hazards 465  References 466  13 Radar Clutter ; 470 ····'"'  13.l Introduction to Radar Clutter 470  13.2 Surface-.Clutter Radar Equations 471  13.3 Sea Clutter 474  13.4 Detection of Targets in Sea Clutter 482  13.5 Land Clutter 489  13.6 Detection of Targets in Land Clutter 497  13.7 Effects of Weather on Radar 498  13.8 Detection of Targets in Precipitation 504  13.9 Angel Echoes 508  References. 512  14 Other Radar Topics 517  14.1 Synthetic Aperture Radar 517  14.2 HF Over-the-Horizon Radar 529  14.3 Air-Surveillance Radar S36  14.4 Height-Finder and 30 Radars 541  14.5 Electronic Counter-Countermeasures 547  14.6 Bistatic Radar 553  14.7 Millimeter Waves and Beyond 560  References 566  Index 571 . .,.,;, PREFACE  Although the fundamentals of radar have changed little since the publication of the first  edition. 
 Some radars operate in a  search, or acquisition, mode in order to find the target before switclling to a trackirlg mode.  Although it is possible to use a single radar for both tile search and the tracking fttnctions, such  CHAPTER FIVE TRACKING RADAR 5.1TRACKING WITHRADAR Atracking-radar systemmeasures thecoordinates ofatargetandprovides datawhichmaybe usedtodetermine thetargetpathandtopredictitsfutureposition. Alloronlypartofthe available radardata-range, elevation angle,azimuth anglc,anddoppkr frequency shift maybeusedinpredicting futureposition; thatis,aradarmighttrackinrange,inangk,in doppler, Ofwithanycombination. 
 The upper sideband isthen selected byacrystal filter. The addition ofthedoppler frequency tothereference signal isequivalent to shifting thephase ofthecoherent oscillator attherate ofje!cps. Itisto benoted that this isnotthesame asmerely tuning thecoherent oscillator tothefrequency fc+~~,since thephase shifter isapplied afterthe oscil- lator islocked. 
  &)'52%  #LUTTER AND TARGET FREQUENCY SPECTRUM FROM A HORIZONTALLY MOVING PLATFORM . 
 MODULATION  ! SINGLE RESOLUTION CELL IN THE RADAR FOOTPRINT MAY  HAVE AN AREA OF n SQUARE KILOMETERS  AND THERE MAY BE HUNDREDS OF CELLS IN THE RADAR FOOTPRINT  SO USING REPRESENTATIVE VALUES OF TARGET 2#3 &IGURE   AND SURFACE SCATTERING COEFFICIENT  Sn &IGURE    THE SIGNAL 
 T2 =    WHERE 42 IS THE PULSEWIDTH   F2 IS THE CARRIER FREQUENCY   S2 IS THE REFERENCE WAVEFORM  TIME DELAY  AND @2 IS THE ,&- SLOPE FOR THE REFERENCE WAVEFORM @2 a @  &)'52%     #ORRELATION MIXER SIGNALS IN STRETCH PULSE COMPRESSION AFTER 2OTH ET AL  "#  $# $#   
 G. W. Ewell and S. 
 Thechiefexample is. ( = 27r(~/X) sin 4  Figure 7.4 Radiation pattern for a uniformly illuminated circular aperture.  the blocking caused by the feed and its supports in reflector-type antennas. 
 3.3 ). However, the difficulty of eliminating the leakage of the transmitter signal into the  receiver has limited the utility of unmodulated CW radar for many Jong-range applications. A  notable exception is the Space Surveillance System (Spasur) for the detection of satellites. 
 CIPAL LIMITATION OF MOST  GENERAL 
 6.8 LIMITERS Applications.  Limiters are used to protect the receiver from damage and to con - trol saturation that may occur within the receiver. When received signals saturate  some stage of the radar receiver that is not expressly designed to cope with such a  ch06.indd   29 12/17/07   2:03:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 There isone subtlety that is worth some discussion. Ifthe + mean orcarrier frequency were anI FIG 5.12.—The upper figure shows, in integral multiple ofthemodulator thefullline curve, theinstantaneous trans- frequency, itisobvious that themitter frequency asafunction oftime. The dotted curve isthereceived frequency. 
 The magnetic field H of the feed is chosen be- cause it leads to the reflector surface current J via the normal to the surface n, by J=Ax//. The primary feed is_assumed to ra- diate with the //field, H(V), perpendic- ular to the direction unit vector v (Fig. 6.23). 
 Theshortcomings werecorrected, andthefirstradarechoesobtained at NRLusingpulsesoccurred onApril28,1936,witharadaroperating atafrequency of 28.3MHzandapulsewidthof5IlS.Therangewasonly2!miles.ByearlyJunetherangewas 25miles. ItwasrealizedbytheNRLexperimenters thathigherradarfrequencies weredesired, especially forshipboard application, wherelargeantennas couldnotbetolerated. However, thenecessary components didnotexist.Thesuccessoftheexperiments at28MHzencouraged theNRLexperimenters todevelopa200-MHz equipment. 
 Older standards required a minimum  antenna rotation rate of 20 rpm, but this explicit requirement has been omitted from  the new standards as other dependent requirements are adequately specified, such  as the maximum relative speed of targets and tracking accuracies. The IMO perfor - mance standards specify that radar equipment should meet the environmental require - ments and test procedures defined within IEC 60945.12 This is a comprehensive set of  requirements that are applicable to all ships’ navigational and radio communications  equipment. They cover such aspects as temperature, shock, vibration, corrosion, and  resistance to water and oil ingress. 
 Campbell, S. D., and S. H. 
 The input signal is–1volt peak; the amplifier output supplies —30volts peak tothecathode oftheindicator tube. The half-power bandwidth is4Me/see. The chassis also contains a6AL5 dual-diode tube. 
 2015 ,63, 828–833. [ CrossRef ] 23. Bi, D.J.; Xie, Y.L.; Ma, L.; Li, X.F.; Yang, X.H.; Zheng, Y.R. 
 ARRAY LEVEL TO REACH A PRESCRIBED PEAK 
 RANGE SPECIALIZED 3"2 SYSTEMS  REVIEWED IN EARLIER EDITIONS  SUCH AS TERMINAL GUIDANCE OR RENDEZVOUS RADARS !LSO NOT  COVERED ARE 4YPE ))) 3"2S  SUCH AS MULTI 
 The work received low priority and was carried out prin­ cipally by R. M. Page, but he was not allowed to devote his full time to the effort. 
 5, pp. 62-66, June, 1968.  96. 
 14.15. The absorption due to oxygen at 60 GHz (5-cm  wavelength) in the clear atmosphere is quite large (about 16 dB/km). Operation at that  frequency is almost useless for radar applications within the earth's atmosphere. 
 The first term of Eq. 3.3 for spectral width due to platform motion approaches zero as  the antenna points ahead. However the second term of Eq. 
 NS PULSE   BEAMWIDTH   OPERATING AT A GRAZING  ANGLE OF ABOUT   VIEWED THE BACKSCATTER FROM A FIXED SPOT ON THE WINDLESS SURFACE OF #HESAPEAKE "AY AS THE RAIN STEADILY INCREASED FROM  TO  MMH 4HE CROSS SECTIONS FOR VERTICAL AND HORIZONTAL POLARIZATIONS WERE QUITE DIFFERENT FOR  LOW RAIN RATES BUT TENDED  TO MERGE AT A RAIN RATE OF ABOUT  MMH 4HE MAGNITUDE OF THIS  SPLASH CROSS SECTION ROSE  TO A R    OF ABOUT n D"  CORRESPONDING TO HIGHLY AVERAGED WIND 
 15.8  Amplitude Characteristics  ..................................  15.10  15.4 Definitions  ...............................................................  15.11  Improvement Factors ( I)  ..................................... 
 161.Ricardi, L.J.:ArrayBeam-Forming Networks, MITLincolnLahoratory Technical Notl!1965-12. 13April1965. 162.Whicker,L.R.,andC.W.Young,Jr.:TheEvolution ofFerriteControl Components, MicrowaL'1! J., vol.21,pp.33-37,November, 1978.. 
 OPERATIVE RADAR TRANSMITTERS v 2ADIO %LECTRON %NG  VOL   PP n  &EBRUARY   % ' -C#ALL  h"ISTATIC CLUTTER IN A MOVING RECEIVER SYSTEM v  2#! 2EV  PP n   3EPTEMBER . 
 ING THE ANTENNAS OF ITS THREE RADARS  #OURTESY  OF .!3!  .   30!#% 
 SPACE  COVERAGE DIAGRAM .   -4) 2!$!2  Ó° 4HE LOSS IN PEAK GAIN FOR THIS EXAMPLE  DUE TO THE BOOST OF COVERAGE AT HIGH ANGLES   WAS ABOUT  D" 4HE COMBINATION OF 34# WITH ENHANCED HIGH 
 SPARX array block diagram. The two transmitting antenna arrays have a uniform spacing of 18 mm and the receiving antenna array has a uniform spacing of 144 mm; as discussed in the previous section, this conﬁguration allow 123. Sensors 2019 ,19, 252 to generate 256 virtual elements uniformly spaced by 9 mm, that correspond to a uniform linear array with a λ/3.44 spacing. 
 22.8 RADAR BEACONS Radar beacons have played an important role in marine navigation ever since the early  days of radar. They basically detect incident pulses from marine radars and instan - taneously transmit a distinctive signal that identifies the beacon and its position on  a radar display. There are three main uses of such beacons. 
 The radar wavelength was 10 cm. These data were obtained exper-  i~nentally by mounting the aircraft on a turntable in surroundings free from other reflecting  objects and by observing with a nearby radar set. The propellers were running during the  measurement and produced a modulation of the order of 1 to 2 kHz. 
 4, p. 1472, October 1999.) 56. F. 
 Colesanti, C.; Locatelli, R.; Novali, F. Ground Deformation Monitoring Exploiting SAR Permanent Scatterers. In Proceedings of the IEEE International Geoscience and Remote Sensing Symposium, Toronto, ON, Canada, 24–28 June 2002; pp. 
 Deam. and A. H. 
 BER OF OPERATIONAL RADAR SYSTEMS ARE ADAPTIVE THEY ARE DESCRIBED IN THE TECHNICAL LITERATURE n  ! MODERN RADAR WITH DIGITAL PROCESSING ALREADY HAS AT LEAST FOUR  DIGITAL CHANNELS SUM  DIFFERENCE IN AZIMUTH  DIFFERENCE IN ELEVATION  AND GUARD  )N GENERAL  THE NUMBER OF IMPLEMENTED RECEIVING CHANNELS IS MAINLY A MATTER OF COST )T HAS BEEN ARGUED THAT RADAR SYSTEMS WITH A NUMBER OF ADAPTIVE DOF OF A FEW TENS  ARE ALREADY IN OPERATION IN THE MICROWAVE BAND THE NUMBER OF ADAPTIVE DOF MAY BE  MORE IN THE OVER 
 Germany has five identical X-band satellites, distributed in three  500-km high orbits, inclined at about 80 °. The aspect ratio of their 3.3 m by 2.7 m  *  Traveling-wave tube amplifier. See Chapter 10 for more discussion.FIGURE 18.3  TecSAR features a symmetrical reflector  antenna, in contrast to the classic high aspect-ratio “billboard”  style pioneered by Seasat. 
 IEEE Geosci. Remote Sens. Lett. 
 Skolnik, M. 1.: A Perspective of Synthetic Aperture Radar for Remote Sensing. Naval ReSt?arch  Laboratory Memorandum Rept. 
 TRAFFIC CONTROL IS A GOOD EXAMPLE !S ONE GOES UP IN FREQUENCY  THE EFFECT OF RAIN ON PERFORMANCE BEGINS TO BECOME SIGNIFICANT  SO THE RADAR DESIGNER MIGHT HAVE TO WORRY ABOUT REDUCING THE EFFECT OF RAIN AT , 
 I.: An Analysis of Bistatic Radar, IRE Trnns., vol. ANE-8, pp. 19 27, Marcli, 1961. 
 Oct.  25 2%. 1977. 
 Actually, much better than this must bedone since the ground returns may be90dborthereabouts above the target returns. Thus, one might expect stabilities ofthe order of10’0 tobe needed. Much calculation can bedone onthis point but, though such calculation was useful inshowing that aworkable system was possible, itwill suffice tosay here that byvery careful attention todetail itwas found possible completely toeliminate alltrouble due tofrequency (and amplitude) modulation ofthetransmitter. 
 1975.  32. Croney, J.: Clutter on Radar Displays, Wireless E~tgr., vol. 
 404–409,  March 1986. 103. W. 
 The previous discussion applies to the rms sidelobe level. This analysis has been  extended by Allen73 to apply the probability of keeping a single sidelobe below a given  FIGURE 13.18  Random errors and rms sidelobes ch13.indd   31 12/17/07   2:40:12 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Raney and J. R. Jensen, “An Airborne CryoSat Prototype: The D2P Radar Altimeter,”  in Proceedings of the International Geoscience and Remote Sensing Symposium IGARSS ’02,  Toronto, IEEE, 2002, pp. 
 Since the fixed error is due to the discrete nature of the frequency counter, its elTects can  he reduced by wobbling the modulation frequency or the phase of the transmitter output.  Wobbling the transmitter phase results in a wobbling of the phase of the beat signal so that an  average reading of the cycle counter somewhere between N and N + 1 will be obtained on a  normal meter movement. In one altimeter,30 the modulation frequency was varied at a 10-Hz  rate. 
 Right-hand and ]eft-hand circular polarization are said to be orthogonal polarizations since an  antenna capable of accepting one wil1 not accept the other. Similarly, horizontal and vertical  linear polarizations are orthogonal. If the radar radiates one sense of circular polarized energy, . 
 SCALE VOLTAGE RANGE OF A .YQUIST RATE CONVERTER IS GIVEN BY  6 &3   .1  WHERE  . IS THE STATED RESOLUTION AND  1 IS THE LEAST SIGNIFICANT  BIT ,3"  SIZE 3IGNAL 
 And what of the smallest detectable target? Coverage and coverage rate? Ship  detection capability versus aircraft detection capability? Clearly, there is no single  preferred metric. The measure adopted here for illustrative purposes is the achievable signal- to-noise ratio (SNR) as defined by the radar equation (Eq. 20.2). 
 Whereas the  ch18.indd   29 12/19/07   5:14:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 7 .40  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 Association (JPDA)65 is an extension of PDA that handles more closely spaced  targets. In JPDA, detections are weighted less when they are near another track. 3. 
 sensitivity-time-control (STC) circuit that gi~~es automatic variation of thesensitivity ofthereceiver asafunction oftheelapsed time after emis- sion oftheinterrogation pulse. The gain isthus automatically adjusted tobecorrect forbeacons atallranges with theresult that they allappear asapproximate half-power bearnwidth arcs. This circuit must becare- fully designed ifitistogive good results with ground radars interrogating beacons onaircraft flying inthemaximum ofthepattern ofthereceiving antenna and still not unduly attenuate weaker replies from beacons in low-flying aircraft. 
 Using an approach similar to that used to resolve the range ambiguity, all possible  radial velocities are then enumerated to the maximum negative and positive radial  velocity of interest on each of the CPIs:  ˆˆ , ( ),...,, max max V v m V m m mi i B i = + ⋅ = − − −1 0 , ,, ,..., int( / )max max m ax ,1 2 1m m V VB i wher e = + i=1 23, , (2.68) In this equation, VB i i , / = ⋅PRFλ2 is the blind velocity for the ith CPI. The pos - sible target radial velocities for all CPIs are then sorted into a single list, and the most  likely true radial velocity is found where at least two possible velocities fall within an  interval less than two or three times the standard deviation of the doppler frequency  estimate. The tightness of the cluster of nearly identical velocities in conjunction with  the number of CPIs contributing to the cluster can be utilized as a measure of reliability  of the unambiguous radial velocity estimate. 
 Antenna Rotation Rate The more slowly the antenna rotates, the greater is the detection range of the radar. For a radar set having a PRR of 1,000 pulses per second, a horizontal beam width of 2.0˚, and an antenna rotation rate of 6 RPM (1 revolution in10 seconds or 36 scanning degrees per second), there is 1 pulse transmittedeach 0.036˚ of rotation. There are 56 pulses transmitted during the timerequired for the antenna to rotate through its beam width. 
 (14.2) into (14.1) gives the cross-range resolution as  bcr = R)./D  The beamwidth of a synthetic aperture antenna of effective length Le is similarly  () s = kA./2Le ( 14 3)  (14.4)  The factor 2 appears in the denominator because of the two-way propagation path from the  .1ntenna "element" to the target and back as compared with the one-way path of a conven­ tit,nal antenna. As a consequence of the two-way path the phase difference between the equally  spaced elements of a synthetic array is twice that of a conventional array with the same  spacing. (The terms synthetic array and synthetic aperture are used interchangeably here.)  Again the factor k will be taken to be unity. 
 For the 16 filters in the above design,  the average mismatch loss is Lm=0 66. d B, a savings of 2.3 dB as compared to the  alternative of a 105 dB weighted Dolph-Chebyshev filter bank. 2.11 PERFORMANCE DEGRADATION   CAUSED BY RECEIVER LIMITING Elsewhere in this chapter (Sections 2.2 and 2.12, particularly) IF bandpass limiters  have been discussed as (1) a means of preventing received clutter signals from exceed - ing the range of the A/D converters, (2) normalizing MTI clutter residue caused by  system instabilities, and (3) normalizing residue due to the spectral spread of “fixed  clutter” caused by either scanning or wind-blown motion. 
 B. Dyer, and R. D. 
 To obtain the target size or shape requires resolution in range and in angle. Good range  resolution is generally easier to achieve than comparable resolution in angle. In some radar  applications it is possible to utilize resolution in the doppler frequency shift as a substitute for  resolution in angle, if there is relative motion between the distributed target and the radar. 
 The effect istogive thestation avirtual velocity which cancels theactual velocity. Figure 16.25b isablock diagram ofthephase-shift unit. Anoscillator supplies asignal atthedoppler frequency which ismixed with therefer- ence signal. 
 I.33  Index terms  Links   Pulse compression radar:  (Continued)   and transmitter 4.27  weighting in 10.29  Pulse doppler radar:  altitude-line clutter in 17.18  ambiguities in 17.5  resolution of 17.19  antenna sidelobes in 17.11  applications of 17.1 17.2  basic configuration of 17.7  clutter in 17.9  comparison of, with MTI 17.2  dynamic range requirements in 17.26  eclipse in 17.26  eclipsing loss in 17.34  guard channel in 17.12  high-PRF ranging in 17.20  linear-carrier FM ranging in 17.23  loss in      17.34  main-beam clutter in 17.16  medium-PRF ranging in 17.25  nomenclature for 17.1  PRF in       17.1 17.5  probability of detection in 17.36  probability of false alarm in 17.35  radar range equation for 17.33  range gating in 17.19  in semiactive missile guidance 19.15  sidelobe clutter in 17.4  spectrum of 17.2  spurious modulations in 17.29  stability requirements for 17.28  This page has been reformatted by Knovel to provide easier navigation. I.34  Index terms  Links   Pulse doppler radar:  (Continued)   STC in       17.12  Swerling target models in 17.38  target tracking in 17.25  time gating in 17.19  Pulse-pair algorithm 23.15  Pulse shaping in transmitters 4.31  Pushing figure 4.8  Q  Quadratic residue sequences 10.21  Quadrature detector 3.33  Quantization effects in phased arrays 7.43  Quantization noise:  in A/D converter 3.40  in MTI radar 15.53  R  Rabbit-ear oscillations 4.16  RAC delay line 10.11  Radar:  block diagram of 1.2  frequencies 1.13  letter-band frequency designations for 1.14  nomenclature 1.18 17.1  Radar cross section:  absorbers and 11.46  of B-26      11.16  bistatic     25.14  of bodies of revolution 11.45  of Boeing 737 11.16  of C-54      11.18  This page has been reformatted by Knovel to provide easier navigation. I.35  Index terms  Links   Radar cross section:  (Continued)   of complex objects 11.13  of cone      11.10 11.32 11.33   11.45  of cone frustrum 11.32 11.33  of cone-sphere 11.45 11.46  of corner reflector 11.14  of cube      11.25  of cylinder 11.21  definition of 11.2  of dipole    11.8  examples of 11.4  of flat plate 11.12  HF           24.10  of insects 11.15  of man       11.16  measurement of 11.34  of ogive     11.9  prediction of 11.18  reduction of 11.43  of ships     11.16  of sphere    11.5  summary of 11.51  summary values of 11.11 11.20  of a wire    11.6 11.8  Radar (range) equation 2.4  for bistatic radar 25.6  Blake's worksheet for 2.63  and chaff    9.31  for clutter 1.10 2.57  derivation of 1.6  factors involved in 2.10  This page has been reformatted by Knovel to provide easier navigation. 
 Transistor amplifiers that utilize Class- C-biased devices exhibit sensitivity to RF drive level that may degrade the output pulse characteristics. The single-stage amplifier will typically exhibit a very nar- row "linear" transfer characteristic; the linear region may exist over only a nar- row 1- to 3-dB window. This becomes strikingly critical when several Class-C- biased stages are cascaded in series, as is common in most amplifier configurations. 
 9.7). During transmission (Fig. 9.7~) the ATR tubes located in a mount between the two  short-slot hybrids ionize and allow high power to pass to the antenna. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 12.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 H-field incident at the surface of the reflector. 
 WAVE(273  HIGH 
 Construction ofRadar Antemas.-The main requirements inthe mechanical construction ofairborne antennas areaccuracy ofform, the ability towithstand field service conditions, and light weight. Surface- based antennas must benoless accurate, and considerations ofweight, inertia, and wind forces are paramount. Considerable advances have been made inthemechanical design ofairborne, and particularly ofsur- face-based, antennas formicrowave radar during the recent war. 
 CORDIC Processor.  An efficient and versatile algorithm that can implement a  phase shift without using multipliers is the COordinate Rotation DIgital Computer  (CORDIC) function, first described by V older7 in 1959. The CORDIC can implement  FIGURE 25.26  Standard complex multiplyA BI QSUM+ − SUM+ +I+ jQ = (A + jB)*(C + jD) = (AC − BD) + j(AD + BC) DC ch25.indd   22 12/20/07   1:40:26 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
                . Óx°£{  2!$!2 (!.$"//+  NOW ALIGNED IN TIME AS THEY PASS THROUGH THE REMAINING PROCESSING DO NOT ACTUALLY COR 
        #$!  "    $ &)'52%  ,EFTMOST &)2 FILTER IN DOPPLER FILTER BANK DESIGN         
 2, pp. 510–525, April 2004. 186. 
 S  THE !32 
 ORDER SCATTERING KERNEL IS MADE UP OF  ELECTROMAGNETIC AND HYDRODYNAMIC TERMS   '' '  %- (9$ 4HE RESULTING PIECEWISE  CONTINUOUS SECOND 
 but the difference is too small in most cases to be of use in reducing the errors due to  multipath. Radar fences. properly located, can mask the surface-reflected signal from the  near-in elevation sidelobes, but they are of limited utility when the main beam illuminates the  top edge of the fence and creates diffracted energy.53 Vertical polarization, often used in  trackers, reduces the surface-reflected signal in the vicinity of the Brewster angle, but has no  special advantage at low angles (less than l.5° over water and 3° over land).45 For a similar  reason, circular polarization has no inherent advantage in improving multipath below eleva­ tion angles corresponding to the Brewster angle. 
 A primary ECCM defense  against RGPO is the use of a leading-edge range tracker. The assumption is that the  deception jammer needs time to react and that the leading edge of the return pulse  will not be covered by the jammer. PRI jitter and frequency agility both help to ensure  that the jammer will not be able to anticipate the radar pulse and lead the actual skin  interval. 
 Root: "Introduction to Random Signals and Noise," chap. 11,  McGraw-Hill Book Company, Inc., New York, 1958.  11. 
 Patent 4,044,359, August 23, 1977. ch24.indd   60 12/21/07   10:52:12 AMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Clutterechoesmaynotalwaysbepresentovertherangeatwhichdetection isdesired.The clutterservesthesamefunction asdoesthereference signalinthecoherent MTI.Ifclutter werenotpresent, thedesiredtargetswouldnotbedetected. Itispossible, however, toprovide aswitchtodisconnect thenoncoherent MTIoperation andreverttonormalradarwhenever sufficient clutterechoesarenotpresent.Iftheradarisstationary, amapofthecluttermightbe storedinadigitalmemory andusedtodetermine whentoswitchinoroutthenoncoherent MTI. Theimprovement factorofanoncoherent MTIwillnot,ingeneral, beasgoodascanbe obtained withacoherent MTIthatemploys areference oscillator (coho).Thereference signal inthenoncoherent caseistheclutteritself,whichwillnotbeasstableasareference oscillator because ofthefinitewidthoftheclutterspectrum causedbyitsowninternal motions. 
 D" 4AYLOR WEIGHTING REDUCES THE PEAK TIME SIDELOBE LEVEL FROM n D" TO  n D" AND INCREASES THE FILTER MATCHING LOSS FROM  D" TO  D" 4HE  
 180 lNTRODUCTION TO RADAR SYSTEMS  Precision " on-axis " Some of the most precise tracking radars are those asso-  ciated with the instrumentation used at missile-testing ranges.62 One such class of precision  tracking radar has been called on-axis The outpiit of a conventional servo system  lags its input. The result of the lag is a tracking error. The on-axis tracker accounts for this lag,  as well as for other factors that can contribute to tracking error, so as to keep the target being  tracked in the center of the beam or on the null axis of the difference pattern. 
 Active EC M is sometimes ref erred lo as jammi11y.  There is also passive ECM. such as chaff, which reflects radar energy to create clutter and false  targets. 
 BASED RADARS USED FOR SEVERE STORM RESEARCH AND WARNINGS NORMALLY USE 3 
 39, pp. 745-808, July 1960. 40. 
 TO 
 10. lOa is equivalent to an  exponential weighting of the received pulses. It results in a loss of about 1.0 dB in signal-to·  noise ratio as compared with the ideal postdetection integrator that weights the received pulses  in direct proportion to the fourth power of the antenna beam pattern. 
 ,-"  4HE EXCITER FUNCTION OF WAVEFORM GENERATION AND UPCONVERSION IS OFTEN TIGHTLY COUPLED  WITH THE RECEIVER FUNCTION 4HE REQUIREMENT FOR COHERENCE BETWEEN THE RECEIVER AND EXCITER IS A MAJOR FACTOR FOR THIS TIGHT COUPLING AND THE USE OF THE SAME ,/ FREQUEN 
 ~.i~li I~~,I:C..I.KONICAI-I.Y si I:I:~II;~) PIIASI.:I) AKKAY AN'IIINNA IN KALIAK 321  (rouglier surface) will give lower sidelobes than an antenna with a larger correlatioti inter-  val. An error stretching most of the length-of the antenna is likely to have a worse effect than  a localized bump or dent of ~nuch greater aniplitude. Therefore small disturbances such as  screws and rivets on the surface of the reflector will have little effect on the antenna  radi;~tiori pattern. 
 Thinning in this manner also gives  rise to phase errors which cause a deterioration in the radiation pattern.  Adaptive antennas. 142-151 An adaptive antenna senses the received signals incident across its  aperture and adjusts the phase and amplitude of the aperture illumination to achieve some  cksircd performance, such as maximizing the received signal-to-noise ratio. 
 Hybrid Processors.  Although it would be very desirable to simply write C code  to implement a complex radar signal processor, the reality in the early 21st century is  that, for many systems, implementing such a system would be prohibitively expensive  or inflict major performance degradation. Although the steady increase in processor  throughput may someday come to the rescue, the reality at this writing is that high- performance radar signal processors are usually a hybrid of application-specific and  programmable processors. 
 PRINT OVER A  KM SWATH ! 42-- FOLLOW 
 GATE CAPACITOR CHARGED POSI 
 Here we can make linear approximations with- . FIG. 12.9 Geometry of doppler-shift calcula- tions for an airborne search radar. 
 By using a push-pull configuration, the circuit designers alleviated some of the low  impedance-matching problems normally associated with very high power transistors.  The RF input drive to the module was 120 W peak and was used to drive two devices.  A combined power level of greater than 600 W was split eight ways to drive the eight  identical output stages. 
 In low-sidelobe applications this amplitude variation may be used in conjunction with the feed pattern to achieve a specific shaping to the skirts of the distribution across the aperture. Although this reflector is commonly illustrated as round with a central feed point, a variety of reflector outlines are in use, as shown in Fig. 6.7. 
 And either way, complex amplitude A is a function  of frequency f, but let’s write A instead of A( f ) for simplicity. In these terms then, what’s special about real signals is that an easily derived  Fourier-transform property requires their Fourier components to occur in conjugate  pairs, so that if there is a component A e j2p  ft at frequency f with complex amplitude  A, there is also a component A* e−j2p  ft at frequency −f with the complex conjugate A*  of that complex amplitude. If a band of positive frequencies from f1 to f2 is occupied  by spectral components, the corresponding band of negative frequencies from −f2 to  −f1 will be occupied by spectral components also, so the two-sided bandwidth must be  twice the one-sided bandwidth. 
 Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 5.2 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 This chapter addresses what  signals are emitted and why they are needed in a  Multifunctional Fighter Aircraft Radar (MFAR). The why begins with typical mis - sions, which shows the geometry that gives rise to each radar mode and waveform,  lists representative radar modes, and shows typical modern airborne radar mode inter - leaving and timing. 
 8 3IGNAL !NALYSIS 3UMMARYn 4ABLE  IS A SUMMARY OF SIGNAL ANALYSIS DEFI 
 D. A,: An FM MTI Cancellation System, MIT Lincoln Lab. Tech. 
 (Sec. 8.2). A similar condition for a synthetic aperture antenna is that the  distance traveled by the radar between pulse transmissions should be less than )./2. 
 Conf. Radar , Paris, France, December 4–8, 1978, pp. 194–200. 
 J.B.G..R.Eames.andK.A.Roche:Moving-Target-lndicator Recursive RadarFilterusing Bucket-Brigade Circuits, ElectrOTlics Lecrers, vol.9,no.4,pp.89-90,Feb.22,1973. 37.Bounden. J.E..andM.J.Tomlinson: CC.D.Chebyshev FilterforRadarMTIApplications, Elec­ IrollicsLepers. 
 DIGITAL !$  CONVERTERS L %XAMPLE RESULTS ARE GIVEN BY !DAMS ET AL  WHO INCLUDE AN )N3!2 IMAGE OF  THE STADIUM AT THE 5NIVERSITY OF -ICHIGAN IN !NN !RBOR  VIEWABLE WITH TWO 
 268-275, May, 1960.  112. Ruze. 
 OUT 
 TAL FILTERS !S MENTIONED EARLIER  FOR EACH PAIR OF POLES AND PAIR OF ZEROS ON THE  :  PLANE  TWO DELAY SECTIONS ARE REQUIRED 4HE ZEROS ARE CONTROLLED BY THE FEEDFORWARD  PATHS AND THE POLES BY THE FEEDBACK PATHS 6ELOCITY RESPONSE SHAPING CAN BE ACCOMPLISHED BY THE USE OF FEEDFORWARD ONLY  WITHOUT THE USE OF FEEDBACK 4HE PRINCIPAL ADVANTAGE OF NOT USING FEEDBACK IS THE EXCELLENT TRANSIENT RESPONSE OF THE CANCELER  AN IMPORTANT CONSIDERATION IN A PHASED ARRAY OR WHEN PULSE INTERFERENCE NOISE  IS PRESENT )F A PHASED ARRAY RADAR SHOULD USE A  FEEDBACK CANCELER  MANY PULSES WOULD HAVE TO BE GATED OUT AFTER THE BEAM HAS BEEN REPOSITIONED BEFORE THE CANCELER TRANSIENT RESPONSE HAS SETTLED TO A TOLERABLE LEVEL  !N INITIALIZATION TECHNIQUE HAS BEEN PROPOSED  TO ALLEVIATE THIS PROBLEM  BUT IT PRO 
 British Patent 13,170, issued to Christian Hiilsmeyer, Sept. 22, 1904, entitled" Hertzian-wave Project­ ing and Receiving Apparatus Adapted to Indicate or Give Warning of the Presence of a Metallic  Body, Such as a Ship or a Train, in the Line of Projection of Such Waves."  3. Marconi, S. 
 Whenseparate poweramplifiers areusedateachelement inatransmitting arrayor. separate receivers are at each element in a receiving array, series-feed arrays are attractive  since their inherent loss is at low-power levels and is made up by the amplifiers. One method  for producing low-power-level beam steering is to use a single series-fed array at frequencyj',  to provide the azimuth phases 4,. 
 Moore, “Effect of pointing errors and range on performance of dual-pencil-beam scat - terometers,” IEEE Trans. , vol. GE-23, pp. 
 55. l3ttck Icy. 1'. 
 For offset-fed reflector configurations, the focal axis generally does not intersect the  reflector surface. Feeds for offset-fed reflectors are generally aimed close to, but  slightly beyond, the center of the reflector area to account for the larger space taper  (spreading loss) on the far side of the reflector. This generally results in a slightly  unsymmetrical aperture illumination. 
 vol. AP-8, pp. 485-490, September, 1960. 
 1998. pp.  12.2 Design of Low Side Lobe Chirp Pulse Compre ssion  12.2.1  Introduction   The increasing use of high duty cycle, solid -state transmitters in modern Radar systems is  making a co mpanion pulse compression subsystem mandatory. 
 Any use is subject to the Terms of Use as given at the website. Radar Receivers. 6.4 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 In the case of very wideband waveforms, analog stretch processing (see Section 6.3) may  be used to reduce the signal bandwidth before subsequent digital signal processing. The receiver discussed herein focuses on those functions that provide analog pro - cessing and digitization of the individual pulse signals with the minimum of distortion,  enabling subsequent digital signal processing to maximize the performance of the  radar. 
 A. Skillman: Master Oscillator Requirements for Coherent Radar Sets, IEEE-NASA Symp. Short Term Frequency Stability, NASA-SP-80, November 1964. 
 Clearly, the TEC differences between GNSS and ISR range from 3 to 5 TECU. Since GNSS measures TEC up to about 20,000 km, the differences are acceptable. However, for group 1 and group 2, the TECs from GNSS are way too large to be believed as precise. 
 Phased array radars are well suited for monopulse track- ing. The radiating elements of the array can be combined in three different ways to give the sum pattern and the azimuth and elevation difference patterns. Con- tradictory requirements in optimum amplitude distribution for sum and difference patterns exist,19 but, as with other antenna systems, they may be independently satisfied. 
 10  www.tektronix.com/radar    Contact Information:   ASEAN / Australia (65) 6356 3900   Austria  00800  2255 4835   Balkans, Israel, South Africa and other ISE Countries +41 52 675 3777   Belgium  00800  2255 4835   Brazil +55 (11) 3759  76 27  Canada 1 800 833  9200   Central East Europe / Baltics +41 52 675  3777   Central Europe / Greece +41 52 675 3777   Denmark +45 80 88  1401   Finland +41 52 675  3777   France  00800  2255 4835   Germany  00800  2255 4835   Hong Kong 400 820 5835   India 000 800 650  1 835  Italy  00800  2255 4835   Japan 81 (3) 6714  3010   Luxembourg  +41  52  675 3777   Mexico, Central/South America and Caribbean 52 (55) 56 04 50 90   Middle East, Asia, and North Africa +41 52 675 3777   The  Netherlands  00800  2255 4835   Norway  800 16098   Peopl e’s Republic of China 400 820 5835   Poland +41 52 675  3777   Portugal  80  08 12370   Republic of Korea 001 800 8255 2835   Russia / CIS +7 (495) 6647564   South Africa +41 52 675 3777   Spain  00800  2255 4835   Sweden  00800  2255 4835   Switzerland  00800  2255 4835   Taiwan 886 (2) 2656 6688   United Kingdom / Ireland 00800 2255  4835   USA 1 800 833  9200   Rev. 01/16                 WWW.TEK.COM     For Further Information   Tektronix  maintains  a comprehensive,  constantly  expanding  collection  of application  notes,  technical  briefs  and other  resources  to help engineers  working  on the cutting  edge  of technology.  Please  visit www.tek.com   Copyright © 201 7, Tektronix. 
 Generally, thefaultliesnotwiththetheory,butinthefactthatitisnotpossible to reproduce precisely inpractice thenecessary aperture illumination specified bysynthesis theory.Small,butever-present, errorsoccurinthefabrication ofanantenna. Thesecontribute unavoidable perturbations totheaperture illumination andresultinapatterndifferent in detailfromtheoneanticipated. Errorsintheaperture illumination maybeclassedaseithersystematic orrandom. 
 RANDOM 
 DAY REVISIT PERIOD -!03!2 4HE -ULTI 
 K. Alexander and R. P. 
 Bean15.16 found that the average value of k  measured at an altitude of 1 km varies from 1.25 to 1.45 over the continental United States  during the month of February and from 1.25 to 1.90 during August. In general, the higher  values of k occur in the southern part of the country. Burrows and Attwood5 state that k lies  between f and 4 in arctic climates. 
 TIME ADAPTIVE PROCESSING FOR AIRBORNE RADAR v -)4 ,INCOLN ,ABORATORY 4ECHNICAL  2EPORT 42n  $ECEMBER     2 +LEMM   0RINCIPLES   OF 3PACE 
 TION  WHICH MEANS THAT THE LEAST SIGNIFICANT BIT ,3"  REPRESENTS A PHASE SHIFT OF O  ,ETS ALSO ASSUME THAT THE TUNING WORD IS REPRESENTED BY  FOR A PHASE INCREMENT OF  O EVERY CLOCK 4HE RUNNING SUM PHASE WOULD STEADILY INCREASE ON EVERY CLOCK  EDGE  BECOMING  O    O   x   O   AND  O  /N THE NEXT CLOCK  EDGE  THE PHASE SHOULD BE REPRESENTED BY  FOR O (OWEVER  WE ARE ONLY PRO 
 Single-cavity output cir- cuits are therefore replaced in broadband klystrons by double-tuned and triple-tuned cavities, sometimes called an extended- interaction circuit,26'27 which uses more than one interaction gap to extract energy from the beam, as shown in Fig. 4.8. This technique of grouping cavities was later extended to the prior cavities as well, and by discovering that the cavities in each group need not be coupled to each other, the clustered-cavity klystron2* has achieved as much as 20 percent band- width. 
 HANDLING CAPABILITY OF THE DEVICE AND  HENCE  THE POWER OUTPUT CAPABILITY OF THE DEVICE  THE EMITTER PERIPHERY IS MAXIMIZED "ECAUSE THE CAPACITANCE OF THE COLLECTOR 
 MINATE THE TARGET RECURRENTLY 4HE SPATIAL SCALE OF THE POLARIZATION hFRINGESv IN THE RADAR FOOTPRINT IS TYPICALLY IN THE RANGE n KM  AND THE CHANGE OF FREQUENCY NEEDED TO ROTATE THE PLANE OF POLARIZATION BY  n AT A GIVEN LOCATION IN THE RADAR  FOOTPRINT THE POLARIZATION BANDWIDTH  IS OF THE ORDER OF  K(Z  SO DIFFERENTIAL . 
 POLAR ICE  %ARTH 
 F.  Earl and B. D. 
 NOISE 
 [ CrossRef ] 18. Wang, Y.; Li, J.W.; Sun, B.; Yang, J. A novel azimuth super-resolution method by synthesizing azimuth bandwidth of multiple tracks of airborne stripmap SAR data. 
 Rhodes. D. R.: "Synthesis of Planar Antenna Sources," Oxford University Press, London, 1974. 
 1977. Redstone Arsenal. Alabama. 
  RADAR FOR THE % 
 Thus noise performance and dynamic range cannot be simultaneously optimized. A solution to this problem may come in the form of an active converter.23 3.5 LOCALOSCILLATORS Functions of the Local Oscillator. The superheterodyne receiver utilizes one or more local oscillators and mixers to convert the echo to an intermediate frequency that is convenient for filtering and processing operations. 
 14.8 MISCELLANEOUSCWRADARS There are several small CW radars for applications that require equipment of modest sensitivity. In all these the homodyne technique is employed, the trans- mitter itself serving as a local oscillator. The transmitter signal reaches the first mixer either by a direct connection or, more frequently, by controlled leakage. 
 Sidelobe Canceler (SLC) System.  The objective of the SLC is to suppress  high duty cycle or even continuous noise-like interferences (NLI) (e.g., SOJ)  received through the sidelobes of the radar. This is accomplished by equipping the  radar with an array of auxiliary antennas used to adaptively estimate the DoA and  the power of the jammers and, subsequently, to modify the receiving pattern of the  radar antenna to place nulls in the jammers’ directions. 
 The processes involved indeducing theplan posi- tion and. theheight ofanaircraft were complicated and notvery reliable. The maximum traffic-handling capacity was low (agood operator could pass about 6plots perminute), and the system could not keep track of large numbers ofindependently routed aircraft. 
 31. B. Kopp, M. 
 sH.Wallman, “Stagger-damped Double-tuned Circuits, ”RLReport h-o.53s, March 23,1944,. 450 THE RECEIVING SYSTEih—RADAR RECEIVERS [SEC. 126 monly used second detectors isthe diode detector shown inFig. 
 Themeasurement ofrangebymeasuring the phase difference betweenseparated frequen­ ciesisanalogous tothemeasurement ofanglebymeasuring thephasedifference between widelyspacedantennas, asinaninterferometer antenna. Theinterferometer antenna givesan accurate butambiguous measurement ofangle.Theambiguities mayberesolved byadditional antennas spacedclosertogether. Thespacingbetween theindividual antennas intheinterfer­ ometersystemcorresponds totheseparation between frequencies inthemultiple-frequency distance-measuring technique. 
 Frush, G. R. Gray, P. 
 3/,!3 #LASSES "  # n n4!",%  !NTENNA 3IDELOBE 0ERFORMANCE 2EQUIREMENTS #OURTESY OF )%#     )%#  ED #OPYRIGHT Ú  )%#  'ENEVA  3WITZERLAND WWWIECCH. 
 The. 104 PROPERTIES OF RADAR TARGETS [SEC. 3.16 urban area ofTokyo isalarge group ofsignals near the southern limit ofthepicture, with the industrial suburbs ofUrawa and Omiya, north- west ofthe city, showing asastrong elongated signal. 
 WIDTH OF THE SIGNAL  THE ENVELOPE OF THE SPECTRUM PEAKS FALLS OFF AT THE RATE OF  D" PER OCTAVE OF BANDWIDTH  AND THIS REDUCTION WILL CONTINUE UNTIL THE ENVELOPE REACHES THE INHERENT NOISE OUTPUT LEVEL OF THE TRANSMITTER 4HIS RATE OF SPECTRUM FALLOFF IS TOO SLOW TO MEET MOST SYSTEM REQUIREMENTS .EVERTHELESS  WITHOUT SPECIAL CARE THE ACTUAL SPECTRUM ENVELOPE MIGHT BE EVEN WORSE THAN THIS  DEPENDING ON TUBE CHARACTERISTICS  AS A RESULT OF PHASE MODULATION DURING THE FINITE RISE AND FALL OF PRACTICAL MODULATOR AND 2& DRIVE PULSE SHAPES )N THESE CASES  EITHER THE LEADING AND TRAILING EDGES MUST BE APPROPRIATELY TAILORED  OR ELSE IN LINEAR 
 The performance of the SLB may be analyzed by looking at the different out- comes obtained as a consequence of the pair (u, v) of the processed signals (see Fig. 9.1&). Three hypotheses have to be tested: (1) the null hypothesis H0 corre- sponding to the presence of noise in the two channels, (2) the H1 hypothesis per- taining to the target in the main beam, and (3) the H2 hypothesis corresponding to target or interference signal in the sidelobe region. 
 Next consider the case where the radar observes surface clutter near perpendicular  incidence. (At perpendicular incidence the grazing angle¢, is 90°.) The clutter area viewed by  the radar will be determined by the antenna beamwidths 08 and </>8 in the two principal planes.  The area Ac in Eq. 
 119-128, Rome Air Dev. Cen- ter, RADC-TDR-62-5SQ, April 1963. CHAPTER 11 RADAR CROSS SECTION Eugene F. 
 This will remain true, even though the antenna rotates, until the rate ofrotation becomes sti great that thebeam dwells onthetarget less than 4see, inother words, upto~rpm. With increasing speed ofrotation, thenumber ofsweeps integrated will decrease as1/(rpm) until the beam rotates faster than onerevolution in4see, atwhich time webegin toinclude more than one scan inthe integration. Then niwill begin tolevel off, itsasymptotic value, forhigh speed, being given by (screen storage time) x(PRF) X‘bea~6~}dth) or,inthis case, n~=33atspeeds much greater than 15rpm. 
 These undulating plate patterns follow a sin x/x variation quite closely for aspect  angles out to about 30 °. Beyond that angle, the two patterns differ by progressively  wider margins. The sin x/x behavior is characteristic of a uniformly illuminated aper - ture, but unlike the one-way illumination function encountered in antenna work, the  argument x for the flat plate includes a two-way (round-trip) illumination function. 
 While noise may be non-Rayleigh, it will probably be very Rayleigh-like out to the  FIGURE 7.12  Cell-averaging CFAR. The letter C indicates a comparison. ( from G. 
 Blackband {ed.), Gordon and Breach, New York, 1966.  72. Benedict, T. 
 If a  current of opposite polarity is passed through the drive wire, the ferrite is saturated with the  opposite polarity of rernanent magnetization. Thus a toroidal ferrite may take on two values of  rnagneti7atior1, f B,, obtained by pulsing the drive wire with either a positive or negative  current pulse. The difference in the two states of magnetization produces the differential phase  Figure 8.1 1 Hysteresis loop, or B-H curve, of a ferrite toroid. 
 SIPATED AND RERADIATED FROM THESE ELEMENTS 4HE SAME MEASUREMEN TS HAVE SHOWN THAT  THE PHASE DIFFERENCE OF THE ENERGY COUPLED TO ELEMENTS IS DIRECTLY PROPORTIONAL TO THEIR DISTANCE FROM THE EXCITED ELEMENTS  INDICATIVE OF A SURFACE WAVE TRAVELING ALONG THE ARRAY  LEAKING ENERGY TO EACH OF THE ELEMENTS &OR BEST PERFORMANCE  THE VELOCITY OF THE SURFACE WAVE SHOULD BE VERY CLOSE TO THAT OF FREE SPACE )F THE ARRAY CONTAINS WAVE 
 Elachi, C., and J. Granger: Spaceborne Imaging Radars Probe "in Depth," IEEE Spec- trum, vol. 19, pp. 
 Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 11.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 The complication in power transistor design extends beyond the exotic material  fabrication technologies that are used to define the basic FET. Tailored construction  techniques are used to control the electric field intensity and improve the breakdown  voltage; enhancements such as the field plate,15,16 double gate recess,17 or automatic  etch stop layers18 are fabrication and design techniques that are used to optimize the  PHEMT performance for a given operating frequency range to bring higher value,  performance, or reliability to the semiconductor fabrication process. 
 WAVE AND SKY 
 fteadrick. J. M.. 
 CENTERED REGIONS 4HE FIRST SUCCESSFUL PIGGYBACK OPERATION IN  EXPLOITED DATA LINK SIGNALS TRANSMITTED FROM THE  ,UNA 
 Randig: Terrain Backscattering Characteristics at Low Grazing Angles for .\'­ and S-Band. Proc. IEEE. 
 Transmitted pulses should be identical. It does  not matter if there is intrapulse amplitude or frequency modulation of the transmitted  pulse, as long as it repeats precisely from pulse to pulse. If the voltage of the trans - mitter power supply varies pulse to pulse, the transmitted pulses will not be identi - cal, and the resulting variations must be quantified to determine if the limitations on  improvement factor fall within the stability budget for the system. 
 Mass, Volume, Stowage, Deployment, and Gimbaling.  The degree to which  these five factors, mass, volume, stowage, deployment , and gimbaling  drive the reflec - tor design vary in accordance with the reflector system and the platform. However,  PLATFORM DRIVES REFLECTOR ANTENNA MECHANICAL DESIGN Ground-based Ship-based Airborne Spaceborne Mass •  Typically not a major  driver. 
 Consequently, they developed, by 1939, an aircraft-interception radar (AI), mounted  on an aircraft, for the detection and interception of hostile aircraft. The AI radar operated at a  frequency of 200 MHz. During the development of the AI radar it was noted that radar could  be used for the detection of ships from the air and also that the character of echoes from the  ground was dependent on the nature of the terrain. 
 C. Taylor: Terrain Scattering Properties for Sensor Systcrn  Ilesign (Terrain Handbook 11). Etryitrtrri~~g E.~perimolt Statiott B~rlletin 110. 
 They could  offer attractive prices as the subsystems were derivatives of the relatively high volume  shipborne market. Over time, much of the market has become more sophisticated, and  because of this, specialist organizations now dominate the supply of systems for this  application. The large costs associated with a major vessel tracking services (VTS)  operation, including massive antenna support towers, operations buildings, special - ized software, and disaster-proofed broadband communication systems, mean that the  costs of a more optimized radar head often become a relatively insignificant addi - tion. 
 TAL MEASUREMENTS OF THE SIGNAL STRENGTH RECEIVED AT A SHORE 
 Figure 15.1 shows the range performance onvarious types ofradar targets asafunction ofthe radar performance figure. Asexplained in Chap. 2,radar range performance does notalways follow thefourth-power law ofEq. 
 DIENT 3TATE 
 However, shear-wave-generated eddies, appearing on SAR images through surface roughness modulation from wave-current interaction, are usually less obvious. Image features of shear-wave-generated eddies are affected by various factors, such as wind, current, seaﬂoor topography, SAR parameters, etc. Features of shear-wave-generated eddies are usually the product of several of the above factors, which are sometimes even hard to recognize. 
 +%%0%2  IS FOR  A SHIPBOARD ANTI 
 For example, the subsidence velocity in NSL is between −15 mm/yr and 5 mm/yr in the study of Bai et al. during 2009–2010, but it exceeds −15 mm/yr in our study during 2015–2018. By comparing and analyzing the results of subsidence monitoring at different times, the law of land subsidence over time in Wuhan city can be revealed. 
 3, in which the doppler frequency shift is extracted as  well as the range. lt will be recalled that the sawtooth frequency-modulated waveform of the  FM-CW radar was capable of determining the range as long as there was no doppler frequency  shift. By using a triangular waveform instead of the sawtooth waveform it was possible to  measure both the range and the doppler frequency. 
 The difference between the two antenna gains is usually small. The  power gain and the directive gain may be related by the radiation efficiency factor p, as follows:  (7.7)  The radiation efficiency is also the ratio of the total power radiated by the antenna to the net  power accepted by the antenna at its terminals. The difference between the total power  radiated and the net power accepted is the power dissipated within the antenna. 
 “Final engineering report on displaced phase center antenna,” vol. 1, March 26, 1956; vols. 2   and 3, April 18, 1957, General Electric Company, Schenectady, NY . 
 As long as the beamwidths of the radar (in azimuth and elevation) are smaller than  the region to be surveilled, this equation is not directly dependent upon frequency.  However, key parameters in this equation are dependent upon frequency. Particularly,  propagation losses for low altitude targets and target RCS (for some target types) are  generally advantageous for lower frequencies. 
 A new method is proposed in [ 10]t o detect stable features by intersecting Coherent Scatters. The stable features are used to achieve thecoarse registration and the Powell algorithm is used for precise registration. A new method using boundary features of images to achieve SAR image registration is proposed in [ 12]. 
 Be wary of vibration and acoustic noise. The facts are as follows: 1. The basic MTI concept does not require a long time on target to resolve targets from  fixed clutter. 
 2.12 The maxima and minima which one might have expected inthe nearer region arenot conspicuous inFig. 2.12. The reason forthis is that thetarget was notapoint with aunique height hzbut acomplicated object extending from thesurface uptosome maximum height. 
 However, from June 2015, the deformation showed a relatively stable performance, and even a slight uplift. 240. Sensors 2019 ,19, 3073 Figure 9. 
 Multi-Angle SAR Imaging Method Based on a Uniﬁed Coordinate 3.1. Problems of Multi-Angle SAR Registrations and Fusion The fusion objects of current SAR images are various remote sensing images, including the fusion of infrared images and SAR images, the fusion of optical images and SAR images, and the fusion of SAR images. Most current SAR image registrations are performed in the image domain. 
 Y . I. Abramovich, N. 
 VI but should be considered for future designs when automatic frequency c o n t r o l( A F C )c o u l db eu s e dt oe a s et h et u n i n gd i f ﬁculties. References [1] ASV Mark VI —ARI 5568, and ASV Mark VIA —ARI 5571, TRE Report T.1664, 16th April 1944 (TNA AVIA 26/666) [2] Lovell B 1991 Echoes of War; The Story of H 2S Radar (London: Taylor and Francis) [3] Pritchard D 1989 The Radar War —Germany ’s Pioneering Achievement 1904-1945 (London: Patrick Stevens) [4] A.S.V. Mk. 
 THE NATURE OF RADAR 9  radiate or project a divergent beam of these rays in any desired direction, which rays, if coming  across a metallic object, such as another steamer or ship, would be reflected back to a receiver screened  from the local transmitter on the sending ship, and thereby, immediately reveal the presence and  bearing of the other ship in fog or thick weather.  Although Marconi predicted and successfully demonstrated radio communication be­ tween continents, he was apparently not successful in gaining support for some or his other  ideas involving very short waves. One was the radar detection mentioned above; the other was  the suggestion that very short waves are capable of propagation well beyond the optical line of  sight-a phenomenon now known as tropospheric scatter. 
 The inverse receiver can be thought of as a double-conversion speedgate with the speedgate AFC loop closed around the microwave LO and the input to the speedgate being the microwave output of the seeker front antenna. The IF spectrum at the mixer output will have the same form as Fig. 19.3. 
 The angle 4  is measured from the cos a, axis, and 0 is measured from the axis perpendicular to the cos a,  and cos a, axes. In Fig. 8.3,4 is taken to be a constant value of 90" and the beam is scanned in  Figure 8.3 Beamwidth and eccentricity of the scanned beam. 
 HEIGHT SPECTRUM OVER ALL FREQUENCIES OR WAVENUMBERS  &OR SPECTRA RESEMBLING THOSE  IN &IGURE   THE RMS WAVEHEIGHT IS GIVEN APPROXIMATELY BY   H RMS   5   M    &)'52%  3EA WAVE FREQUENCY SPECTRA OF THE 0IERSON 
 If n pulses are integrated, the integration-improvement factor Ii(n) = nEi(,r) is found from  Fig. 2.24. ?'he parameters (SIN), arid nEi(rt) are substituted into tlie radar equation (2.33)  along with o,, . 
 10. The receiver is not  designed as a tt~atcltedfilter. for the particular transmitted waveform. 
 30 2.9 Receiver Bandwidth and Pulse Energy 33 2.10 The Statistical Problem 35 2.11 Effect ofStorage onRadar Performance 41 MICROWAVE PROPAGATION 47 2.12 Propagation over aReflecting Surf arc 47 2.13 The Round Earth. 53 2.14 Superrefraction 55 2.15 Attenuation ofMicrowaves inthe Atmosphere 58 CHAP. 3. 
 POLARIZED RETURNS  LYING IN THE CROSS 
 SPEED CRAFT  SUCH AS MULTI 
 12.18  CW and FM-CW Systems  ..................................  12.18 Range-Measuring Systems  ................................  12.21  CW-Doppler Scatterometers  .............................. 
 The wideband  amplifier allows a rapid recovery time from the effects of the swept jammer, and the  limiter cuts the jamming signal. The narrowband target signal, after transit through the  wideband amplifier and the limiter without remarkable degradation, is integrated by   the narrowband filter matched to the signal. The word Fix in the Dicke-Fix was put there  many years ago to indicate it was a “fix” for a problem that occurred at the time and was  to be replaced by something better. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.616x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 For an active array, both the phase and amplitude of each element must be measured  in order to determine the correction constants for each array element in both transmit  and receive mode. Full calibration of an active array is measurement intensive. 
 A cluster of such simultaneous receiver beams requires a wider trans - mitter beam. This may be obtained efficiently from the same antenna with a gabled or  spherical phase distribution. With identical subarrays, a desired aperture amplitude taper (for low sidelobes) is  applied with a granularity that depends on their size and shape. 
 AP-16, pp. 217–223, 1968. 66. 
 W. S. Pringle. 
 Even for comparatively thin coatings of water, the compostte  particle scatters nearly as well as a similar all-water particle.  Radar observations of light precipitation show a horizontal "bright band" at an altiiude  at which the temperature is just above 0°C. The measured reflectivity in the center of the bright  band is typically about 12 to 15 dB greater, than the reflectivity from the snow above it and  about 6 to 10 dB greater than the rain' below.70 The center of the bright band is generally from  about 100 to 400 m bklow the O°C'isotherm. 
 Radar System Engineeri ng Chapter 8 – Pulse Radar  62     The third version of non- coherent integration is binary integration and it digitally analyzes the  number of occurrences in a wi ndowed range.  Figure 8.18 shows a corresponding arrang e- ment.   Radar receiverThreshold detectorQuantizerRange gate No. 
 Equation (2.29) may be converted to power by replacing the  signal to nns-noise-voltage ratio with the following:  A signal amplitude J1(~ms si_gnal voltage) = (2 sig~al power) 112 = (2S) 112  tJrA'2 = rms noise voltage rms noise voltage noise power N  We shall also replace Vf/2t/t0 by In (l/Pra) [from Eq. (2.24)1. Using the above relationships,  the probability of detection is plotted in Fig. 
 A 11i;tjor ;icIv;iricc iri ~di:tsecl-;irrwy tecli~iology was rnade in the early 1950s with the  rcplacetlienr of riiechariically :tc~uated phase shifters by electrorlic phase shifters. Frequency  scanriirig in one angular- coordirlate was the first successful electronic scanning technique to bc  applied. I11 terms of riuriibcrs of operatiollal radars, frequency scanning has probably seen  riiore ;ipplicatiori that1 ariy other electronic scanning method. 
     . Ó£°ÎÈ  2!$!2 (!.$"//+  !RCHAEOLOGICAL APPLICATIONS OF '02 HAVE BEEN VARIED  RANGING FROM THE EXPLORA 
 Nonlinearity at any stage has the potential to mask target echoes by  mixing the clutter echo with itself, generating IMD products that extend beyond  the intrinsic doppler band of the clutter. Unlike the out-of-band IMD, in-band IMD  can occur at any stage through the receiver, and hence even second-order products  may cause problems.122 ch20.indd   47 12/20/07   1:16:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 16.7  16.4 Platform-Motion Com pensation Abeam   ..................  16.8  Physically Displaced Phase- Center Antenna   ......  16.8 . 
 During those  minute silent intervals the energy is reflected back from the distant object, and our receiver has given one spurt  of its CRT display. : _ Design of the Mod and its pulse-shaper has been one of the intricate tasks of radar experts. Later on, when we look at the pulse system in more technical detail, we shall see just why it is a difficult job. 
 TIAL 
 JECTORY  THE !& WILL MOVE ACCORDINGLY AND THE SPURIOUS !& PEAKS WILL SLIDE ACROSS THE CLUTTER AND CHAFF REGIONS DETERMINING THE INTENSITY AND FEATURES OF THE RADAR ECHOES 7AVEFORM CODING INCLUDES 02& JITTER AND 02& STAGGER  WHICH ARE HELPFUL FOR SOME  DECEPTION JAMMER BUT DONT HELP AGAINST NOISE JAMMER 7AVEFORM  CODING MAKES DECEP 
 40. Milne, K.: The Combination of Pulse Compression with Frequency Scanning for Three-Dimensional  Radars, Radio and Electronic Engineer, vol. 28. 
 x. ASV radars played a very important role in the battle against the U-boats in WWII and their modern successors continue to be developed to this day. I hope that readers of this book will gain an insight into the fascinating technology develop-ments and achievements in this ﬁeld. 
 G. Rutten and D. J. 
 as a thyratron or ignitron is capable of handling high power and presents a low impedance  wllerl conducting. However, a gas tube cannot be turned off once it has been turned on unless  the plate current is reduced to a small value. The switch initiates the start of the modulator  pulse by discharging the pulse-forming network, and the shape and duration of the pulse are  determined by the passive circuit elements of the pulse-forming network. 
 If the bandwidth of the receiver passband is wide compared with that occupied  by the signal energy, extraneous noise is introduced by the excess bandwidth which lowers the  output signal-to-noise ratio. On the other hand, if the receiver bandwidth is narrower than the  bandwidth occupied by the signal, the noise energy is reduced along with a considerable part  of the signal energy. The net result is again a lowered signal-to-noise ratio. 
 Provision can bemade forshortening pulse length bybringing outtaps onthe pulse line. However, this israther difficult athigh power, because oftheproblem ofdesigning suitable line switches. The Sw”tch.—The possible advantages ofthe line-type pulser greatly stimulated the design oflow-impedance spark switches and thyratrons, since itbecame possible tosecure flat-topped pulses without thenecessity ofopening the switch. 
  
 ARRAY RADAR OPERATING AT 3 BAND "OTH CANCELERS PROCESS AN  PULSE COHERENT BURST 4HE FIXED IE  NONADAPTIVE  PROCESSING IS A $OLPH 
 1.2TheAGCinamonopulse radarisaccomplished byemploying i:I voltageproportional tothesum-channel IFoutputtocontrol thegainofallthreereceiver channels. TheAGCresultsinaconstant anglesensitivity independent oftargetsizeandrange. WithAGCtheoutputoftheangle-error detector isproportional tothedifTtJrence signal normalized (divided) bythesumsignal.Theoutputofthesumchannel isconstant. 
 Maese, J. Melody, S. Katz, M. 
         &)'52%   %LECTRIC FIELD PLOT ON A VERTICAL CUT PLANE AFTER THE MAIN GROUND  REFLECTION #OURTESY )%% . Ó£°£n  2!$!2 (!.$"//+  &)'52%   4YPICAL HYPERBOLIC IMAGE OF '02 DATA FROM A REFLECTOR OF CIRCULAR  CROSS SECTION #OURTESY )%%         4HIS EQUATION SHOWS THAT THE MEASURED WAVEFRONT APPEARS AS A HYPERBOLIC IMAGE  OR A CURVE OF MAXIMUM CONVEXITY -IGRATION TECHNIQUE MAY BE USED TO MOVE OR  MIGRATE A SEGMENT OF AN ! 
 This method ofusing alin-log receiver should beused only when simplicity and compact ness areofprime import ante. Ingeneral, such areceiver should beused inconjunction with anoscillator and amplifier (Fig. 16.11)intheusual way. 
 Theamountofinformation thatcanbedisplayed islimitedbythe spotsize,whichinahigh-performance displayislessthan0.1percentofthescreen diameter.17 Insomehigh-range-resolution radars,however, thenumber ofresolvable rangecellsavailable fromtheradarmightbegreaterthanthenumber ofresolution cellsavailable onthePPI screen.Theresultisacollapsing loss(Sec.2.12).Increasing theCRTdiameter doesnot necessarily help,sincethespotdiameter varieslinearly withthescreendiameter. Another limitation isthedynamic range,orcontrast ratio,ofanintensity modulated displaywhichisof theorderof10dB.Thismightcauseblooming ofthedisplaybylargetargetssoastomaskthe blipsfromnearbysmallertargets. ..} Thedecayofthevisualinformation displayed ontheCRTshouldbelongenoughtoallow theoperator nottomisstargetdetections, yetshortenoughnottoallowtheinformation paintedononescantointerfere withthenewinformation enteredfromthesucceeding scan. 
 The SNR increases as N. • The last trace shows a noncoherent integrated signal. • Integration improvement an example of  processing gain . 
 A boresight telescope mounted on the radar antenna permits calibration of the mechani-  cal axis of the antenna with respect to a star field. This calibration accounts for bias in  azimuth and elevation, mislevel, skew, droop, and nonorthogonality. Tracking a visible satel-  lite with the radar permits the position of the RF axis relative to the mechanical (optical) axis  to be determined. 
  SHARE SOME COMMON FEATURES /NE IS THE ROUNDED WINGTIPS  WHICH TEND TO REDUCE TIP 
 TO 
 S.: Toward a Theory of Reflection by a Rough Surface, Proc. IRE, vol. 41, pp. 
 12 Frequency modulation-versus-time for sine-based NLFM, tangent-based  NLFM, and LFM waveforms FIGURE   8. 13 Matched filter output of S band, 44-µs pulsewidth, 5-MHz band - width NLFM sine-based waveform with 500 m/s radial velocity ( Courtesy of Edwin M.  Waterschoot, Lockheed Martin Maritime and Sensor Systems, Syracuse, NY )0 −10 −20 −30 −40 −50 −60Magnitude (dB) Time (usec)−2.5−2−1.5−1−0.5 0 0.5 1 1.5 2 2.5 ch08.indd   15 12/20/07   12:50:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Although sequential  lobing is similar to conical scan, the'littei*ispreferred in most applications, since it suffers less  loss and the antenna and feed ~yst'kmk~are usually less complex. In this section, only the  conical-scan radar and the amp~itiid~~omparison monopulse will be compared. (The latter  will be referred to simply as mon'opulse,)  When the target is being tracked, the signal-to-noise ratio available from the monopulse  radar is greater than that of a %oniciil:scan radar, all other things being equal, since the  I* ,#J' monopulse radar views the target at'the'pak of its sum pattern while the conical-scan radar  views the target at an angle off thi"peak of the antenna beam. 
 IET Radar Sonar Navig. 2012 ,6, 332–340. [ CrossRef ] 27. 
 FOOT QUASI 
 The MTI design is further complicated if the moving chaff appears in the same  resolution cell as stationary surface clutter. The MTI must then be made to cancel simulta­ neously both stationary surface clutter and moving volume clutter. High range and angle  resolution is another technique effective in reducing the amount of clutter with which the  target must compete. 
 However, in practice, leakage between transmitter and receiver can  limit the sehsitivity of the CW doppler-navigation radar, just as it does in any CW radar. One  method of eliminating the ill effects of leakage is by pulsing the transmitter on and turning the  receiver off for the duration of the transmitted pulse in a manner similar to the pulse-doppler  radar described in Sec. 4.10. 
 This involved making  the transmitting aerial directional, and rotating it, or  swinging it over an arc wherein the distant object might  be. An equally directional aerial could be used to receive  the echo, and, of course, the receiving aerial could be  swung in synchronism and in line with the transmitting  aerial. The higher frequencies (thus the shorter wave-  lengths) we use the easier it is to concentrate our trans-  mitted beam with aerials and reflectors of reasonable  proportions. 
 W. D. Fitzgerald, “Limited electronic scanning with a near-field Cassegrainian system,”  Technical Report 484, MIT Lincoln Laboratory, 24 September 1971. 
  RADAR ALTIMETER EXPERI 
 8.5 and 8.6 lend themselves to the use of semiconductor diodes.  Ferrite phase shifters are also operated digitally, but in a slightly different manner, as described  later.  Diode phase shifters.22 26·155 The property of a semiconductor diode that is of interest in  microwave phase shifters is that its impedance can be varied with a change in bias control  voltage. 
 ,3 
 Therefore, when the full polarimetric data is obtained, TEC can be calculated from Equations (1) and (2). 2.2. Improving the T opside Proﬁle Model of Ionosonde with Known TEC Many models are available for the topside proﬁle of ionosonde. 
 N. J. Willis, “Bistatic radar,” Chapter 25, in Radar Handbook , M. 
 (IGGINS AND * 3 4URNER h!N @ENTRAINING PLUME MODEL OF A SPILLING BREAKER v   * &LUID -ECH  VOL   PP n  . 
 M. Fuks, A. I. 
 P. J. Gaudreau et al., “Solid state radar modulators,” presented at 24th International  Power Modulator Symposium, June 2000. 
 f·  10. Gray. C. 
 H. Taylor, L. C. 
 WAVE SEARCH RADARS4ARGETS  SEA CLUTTER  AND THE DETECTION PROCESS v  0ROC /#%!.3      PP n    7 + 2IVERS  h,OW 
 55. H. A. 
 The electrical length of the coupling loop isalso varied with the plate tuning. The monitor diode rectifies asmall portion oftheoutput signal, which isdisplayed ona scope formonitoring purposes. Areflectometer, orbidirectional coupler, iscoupled into ther-fline atalltimes. 
 69. Newburgh, R. G.: Basic Investigations of the RADAM Effect, Rome Air Development Center, New  York, Report RADC-TR-78-151, June, 1978, AD A058099. 
 TIALLY THE GAIN AND BEAMWIDTH OF THE WHOLE ANTENNA !LLEN  HAS SHOWN THAT THERE ARE  EFFICIENT EQUIVALENT TRANSMISSION NETWORKS THAT USE DIRECTIONAL COUPLERS AND HAVE THE SAME COLLIMATING PROPERTY ! TYPICAL FORM  AFTER "LASS   IS SHOWN IN &IGURE  D  4HE GEOMETRY CAN BE ADJUSTED TO PROVIDE EQUAL PATH LENGTHS  THUS PROVIDING FRE 
 X-band radars have been considered to  some degree but the more severe attenuation that can occur in very heavy rain will  limit performance unless the radar is located very near to the airport runways. In  the mid-1990s the C-band Terminal Doppler Weather Radar (TDWR) system was  installed at 45 major airports to detect and warn aircraft of hazardous wind shear  conditions, approaching gust fronts that may affect the airport approach and departure  configuration, and microbursts.7 This network of radars along with much improved  pilot training and awareness has all but eliminated aircraft accidents caused by micro - bursts and strong wind shear. Hail. 
 ING HIGHER SPACE AND TIME RESOLUTION  FOR IMPROVED DATA QUALITY  AND FOR THE PRODUCTION OF NEW WEATHER RADAR PRODUCTS ALL OF WHICH HAVE LED TO DRAMATIC IMPROVEMENTS IN WEATHER FORECASTING $OPPLER WEATHER RADARS MEASURE DETAILED VECTOR WIND FIELDS AS WELL AS PRECIPI 
 Cheng, Y.; Sun, C. Applications of superresolution signal estimators to Doppler beam sharpened imaging. J. 
 Countless generations before the first radar system  was devised by man Nature had given us a perfect  example of a workable radar navigational aid in the  mechanism which enables bats to fly. Recent research,  in the light of our present knowledge, shows that the  bat is provided with a mechanism which is a strange  parallel of radar.  In the first-devised radar systems a pulse of radio  energy is transmitted at a very high frequency many  times a second; as each pulse strikes an object there is  a reflection, received during the silent period before  the next pulse is transmitted. 
 Discrimination isperformed eitherhythe radaroperator orautomatically withMTI. Chaffdropped fromanaircraftcanalsobeusedto"breaklock"ontracking radars;that is,ifatracking radaris"lockedon"andfollowing aparticular target,thedropping ofchaff mightcausethetrackertofollowthechaffandnotthetarget.. ('IlafP was a very clfcctivc countcrliieasilrc wlictl used with tlic rcliltivcly slow bomber  aircraft of World War 11. 
 As the presented EMAM method is an extension of the basic MAM method, it is necessary to ﬁrstly give a brief introduction to the basic MAM method as follows. Assume that the signal at a certain range cell is expressed as (1) (ignoring the azimuth four-order and higher order terms of the phase). s(ta)=rect/parenleftbiggta Ts/parenrightbigg exp/parenleftBig j2πfdcta+jπfdr,at2 a+jπf3rd,at3 a/parenrightBig , (1) 53. 
 16.33.—A folded mercury deIay line.The line, with expansion chamber and electrical end housings, is shown shock-mounted inather- mally insulated box. This line was designed foruseat30Me/see. Quartz-to-quartz parallelism is maintained to0.03° Astraight tube having the length necessary for1ow-PRF sys- tems would beinconvenient for field use. 
 The radar equation was derived inChap. 2forthecase ofadiscrete target with cross section O,Eq. (2W). 
 The radar cross  section of the T-38 aircraft at head-on incidence is shown in Table 2.1. This data was also  obtained from an aircraft in flight. (The T-38 is a twin-jet trainer with a 7.7 m wing span and a  14 m length.)  40INTRODUCTION TORADAR SYSTEMS 35dB Figure2.16Experimental crosssectionofthe8-26two-engine bomberatto-emwavelength asafunction ofazimuth angle.(FromRidenour,28 courtesyMcGraw-Hill BookCompany, Inc.) accountofaspectchangesandshadowing ofonecomponent byanother) iscomputed andthe component crosssectionsarecombined toyieldthecomposite value.The"theoretical" values ofFig.2.17forB-47wereobtained bycalculation. 
 This is in contrast to shot noise  or thermal noise, which is independent of frequency. Thus, at the lower range of frequencies  (audio or video region), ·where the doppler frequencies usually are found, the detector of the  CW receiver can introduce a considerable amount of flicker noise, resulting in reduced receiver  sensitivity. For short-range, low,..power.! applications this decrease in sensitivity might be  tolerated since it can. 
    (  
 PULSE FREQUENCY AGILITY  HOWEVER  IS NOT COMPATIBLE WITH THE USE OF DOPPLER PROCESSING TO DETECT MOVING TARGETS IN CLUTTER   BUT FREQUENCY DIVERSITY CAN BE COMPATIBLE 4HE FREQUENCY RANGE IN BOTH AGILITY AND IN DIVERSITY OPERATIONS IS MUCH GREATER THAN THE INHERENT BANDWIDTH OF A PULSE OF WIDTH  S %LEVATION .ULL &ILLING  /PERATION OF A RADAR AT A SINGLE FREQUENCY CAN RESULT IN A  LOBED STRUCTURE TO THE ELEVATION PATTERN OF AN ANTENNA DUE TO THE INTERFERENCE BETWEEN THE DIRECT SIGNAL RADAR TO TARGET  AND THE SURFACE 
 37) theparts ofthesignal \vhere there isnooverlapping areseparated byagap of zero power due todestructive interference inthe overlapping region. InFrame h-o. 0303 and in Frame No. 
 Conical-scan processing requires that both the amplitude and the phase of the AM be preserved (at least one cycle of the scan is needed to make an angle mea- surement). The AGC which is required for gain normalization must therefore be slow enough not only to prevent it from following the scan AM envelope but to avoid any phase shift of the envelope15 (since this would cause cross coupling between channels; i.e., a pitch error would couple into the yaw plane, and vice versa). Thus any externally generated amplitude fluctuations (propeller modula- tion, target fading noise, or jamming) at or near the scan frequency will be de- tected along with the target BSE and will result in noise or false data. 
 The American equipment which resulted isthe SCR-720. Inthis equipment, a29-in. paraboloid reflect orrotates continuous yinazimuth and isS1OW1 ytilted inelevation. 
 ·  53. Davenport, W. B., Jr.: Signal-to-noise Ratios in Band-pass Limiters, J. 
 5.15 isactually periodic and could therefore beremoved byfilters with infinitesimal bandwidth. Actually theground returns vary, with theresult that thefilter rejection bands must have afinite width. Using some data ofH.Goldstein, 1a width of4cycles 12dbupfrom the 92-db bottom ofthe’ curve was chosen. 
 T. Ulaby “The active and passive microwave response to snow parameters,  Part I: Wetness,” J. Geophys. 
 The term bird actitiitymod"lation (BAM) has been applied  to the distinctive waveforms obtained from hirds.92 The spectral components of the BAM  pattern or a bird in flight are said to be remarkably stable97 and suited for dekrmining  identity.  Insects. 120 Even though they are small, insects are readily detected by radar, and in sufficient  numbers can clutter the display and reduce the capability or a radar to detect desired targets A  radar cross section or 0.1 cm 2, which might correspond to an insect the size of a housetly at K,. 
 POWER KLYSTRONS ARE EMPLOYED IN LINEAR ACCELERATORS SUCH AS FOUND AT THE  3TANFORD ,INEAR !CCELERATOR #ENTER  +LYSTRONS FOR THIS APPLICATION  FOR EXAMPLE  MIGHT  HAVE  -7 PEAK POWER WITH  EFFICIENCY USING SOLENOID MAGNETS OR n -7 PEAK POWER WITH  EFFICIENCY USING PERIODIC PERMANENT MAGNETS )MPROVEMENTS TO THE KLYSTRON AS A RADAR POWER SOURCE ARE DISCUSSED LATER IN THE  SUBSECTION ON HYBRIDS  OF WHICH THE CLUSTERED 
   
 Permanent magnet Cathode-ray tube. 5FP14 (or5FP7) Video bandwidth.. :..:::: :::” ”::....sec/sec Antenna Reflector ....................... 
 Logarithmic devices and IF amplifiers are devices whose output is proportional to the logarithm of the envelope of the IF input. They often ap- proximate the logarithmic characteristic by multiplicity of linear segments. Nor- mally linear segments of equal length ratio and varying slope are joined to give a best fit to a logarithmic curve. 
 TO 
  FOUR 
 (Pulse-doppler radars  usually operate in this manner). As will be described later, the effect of blind speeds can be  significantly reduced, without incurring range ambiguities, by operating with more than one  pulse repetition frequency. This is called a staggered-prfMT1. 
 ·  75. Hadjifotiou, A.: Round-off Error Analysis in Digital MTI Processors for Radar. The Radio and  Electronic Engineer, vol. 
 In this  version of a pulse-compression radar the transmitter is frequency modulated and the receiver  contains a pulse-compression filter (which is identical to a matched filter). The transmitted  waveform consists ,of a rectangular pulse of constant amplitude A and of duration T  (Fig. 11.15a). 
 The operating characteristics that result from this difference have tre- mendous impact on the overall system design. The peak power output of micro- wave transistors is limited by electrical characteristics, while the average power output capability is determined by thermal layout of the transistor. Transistors can be designed to operate for short (< 10 JJLS), medium (10 to 150 JJLS), or long ( > 150 JJLS) pulse widths and for duty cycle ranges to CW. 
  
 PHASE  QUADRATURE  SAMPLING OR DIRECT SAMPLING WITH THE ) AND 1 DATA CONSTRUCTED AFTER THE !$ 4HE LIMITER MUST BE DESIGNED TO MINIMIZE THE CONVERSION OF AMPLITUDE TO PHASE NO MATTER HOW MUCH THE SIGNAL LEVEL EXCEEDS THE LIMIT LEVEL )F CLUTTER SATURATES THE !$  THE )  1 DATA IS SIGNIFICANTLY COR 
 This sector can bechosen by ,= adjustment ofacalibrated control.c The RHI isalways used inconjunc- ~ tion with aPPI orother display ofthe ~ horizontal plane; usually this auxlhary G~~~”d ~ indicator obtains itsdata from another Slantrangeinmiles radar set. The signals from agiven tar- F,G. 6.10. 
 £Î°£* >Ãi`ÊÀÀ>ÞÊÊ ,>`>ÀÊÌi>Ã iÊÀ> *OHNS (OPKINS 5NIVERSITY !PPLIED 0HYSICS ,ABORATORY  Ê °Ê,V >À`Ã *OHNS (OPKINS 5NIVERSITY !PPLIED 0HYSICS ,ABORATORY £Î°£Ê  /," 1 /"  0HASED !RRAY 2ADARS  %ARLY RADAR SYSTEMS USED ANTENNA ARRAYS FORMED BY THE  COMBINATION OF INDIVIDUAL RADIATORS 3UCH ANTENNAS DATE BACK TO THE TURN OF THE TWEN 
 The angular distance between  the nulls adjacent to the peak is 2)/a rad, and the beamwidth as measured between the half­ power points is 0.88.,l/a rad, or 5 U./a deg. The voltage pattern of Eq. (7.16) is positive over the  entire main lobe, but changes sign in passing through the first zero, returning to a positive  value in passing through the second zero, and so on. 
 Nodding-beam heightfinder.Justastherange-azimuth coordinates ofatargetcanbeobtained withaverticalfan-beam antenna, theelevation coordinate canbeobtained withahorizontal fanbeam.(Thethreecoordinates canthusbeobtained withtwo2D-radars.) Suchaheight finderwouldbedirected bythe2Dair-surveillance radartotheazimuth ofthetarget.Itthen. scans its horizontal fan beam in elevation to make an elevation angle measurement of the  target found at the range designated by the air-surveillance radar. The nodding-beam height  Jinder scans its beam in elevation by mechanically rocking the entire antenna. 
 and H. Weil: Forward Scattering by Coated Ohjects Illuminated hy Short  Wavelength Radar. Proc. 
 B. Pendleton: Tracking Radar, chap. 2 1 of "Radar Handbook,"  M. 
 12. YIa mea- sures transmitter power and receiver sensitivity separately. The transmitter feeds an antenna through a directional coupler so that a portion of the energy may be fed to a power meter. 
 Van Nostrand  Company, 1961, pp. 397–399. 43. 
  
 BOARD AND LAND 
   (& /6%2 
 53.Ward,H.R.,andW. W.Shrader: MTIPerformance Caused byLimiting, EASCON '68Record, Supplement toJEEETrans,vol.AES-4,pp.168-174, November, 1968. 54.Grasso, G.:Improvement FactorofaNonlinear MTIinPointClutter,IEEETrans.,vol.AES-4, pp.640-644, July,1968. 
 Angle (deg) Noise (dBW) Loss (dB) Frequency (MHz) or El. Angle (deg) Noise (dBW) Ground Range (nmi) (b) FIG. 24.23 Radar performance estimate; July, 0800 UTC. 
 18.7 Error slope ks and crossover loss LA.3-dBCONTOUR CENTER OFANTENNABEAM AXISOFROTATIONTARGET LOCUS OFANTENNA BEAMCENTER ONE-WAYANTENNA PATTERN(BEACON CASE) NEAR OPTIMUM TWO-WAYANTENNA PATTERN(REFLECTIONCASE) NEAR OPTIMUM REFERENCEAXIS CROSSOVER LOSS Lk(dB) CROSSOVER LOSSLk (dB) vERROR SLOPE k s, PER BEAMWIDTH ERRORSLOPE K31PERBEAMWIDTH . of zero maximizes range-tracking performance. Therefore, values of £ indicated by the vertical dashed lines are chosen smaller than optimum for angle tracking as a compromise between angle- and range-tracking performance. 
        
 1969. 104.Kay,A.F.:Electrical Designoftltfetal SpaceFrameRadomes, IEEETrans.,vol.AP-13,pp.IH8-202, March, 1965. 105.Larrench, W.:AHomogeneous, Rigid,Ground Radome, Proc.IEE, vol.109B,pp.445446, Novem­ ber,1962. 
 263 88Reply Codes ....... 264 STATISTICAL CONSIn ERATION-S. 265 89TrafficC apacity ...... 
 BEAM SLOPE FROM THE MONOPULSE COMPARATOR 4HE FORMER REQUIRES A SMALL OVERALL FEED SIZE  WHEREAS THE LATTER REQUIRES LARGE INDIVIDUAL FEEDS &IGURE   .UMEROUS DESIGN METHODS HAVE BEEN DEVISED TO OVERCOME THIS PROBLEM  AS WELL AS THE ASSOCIATED HIGH DIFFERENCE PATTERN SIDELOBES 4HESE METHODS EITHER USE DIFFERENT SETS OF FEED ELEMENTS FOR THE SUM AND DIFFERENCE BEAMS OR APPLY DIFFERENT ARRAY AMPLITUDEPHASE WEIGHTINGS FOR EACH OF THE BEAMS )F HORN FEED ELEMENTS ARE USED  ONE APPROACH IS TO OVERSIZE THE FEEDS TO ENABLE MULTIMODE EXCITATION FOR THE SUM BEAM AS DESCRIBED BY (ANNAN  ! COMPARISON  OF SOME COMMON MONOPULSE FEED CONFIGURATIONS IS INCLUDED IN 4ABLE             
 CONNECTED INDUCTIVE REACTANCES AS WELL AS SHUNT CAPACITIVE REACTANCES  ARE THE MOST EASILY FABRICATED AND MOST FREQUENTLY USED MATCHING ELEMENTS 0OWER #OMBINING  ! POWER COMBINER COHERENTLY ADDS TOGETHER THE 2& OUTPUT  VOLTAGES OF INDIVIDUAL AMPLIFIERS AND DELIVERS THE SUM TOTAL OF THE MODULES OUTPUT POWER  MINUS THE LOSSES OF THE COMBINER  TO A SINGLE PORT 4HE OUTPUTS OF IDENTICAL SINGLE 
 TO 
 geological and rnitleral explorations, and other remote sensing  application^.^^  'I'lie resolutio~i it1 the cross-range dimension or a conventional antenna is  wliere R is the range and OR is the beamwidth. The narrower the beamwidth, the better the  resolution (smaller h,,). There is a limit, however, to the minimum beamwidth of a practical  microwave antenna because of tlie difficulty of achieving and maintaining the necessary  mechanical and electrical tolerances (Secs. 
  TO SIGNIFICANTLY IMPROVE WHAT COULD BE ACCOMPLISHED WITH THIS RADAR  !S MENTIONED  SOLID 
 POWER EFFICIENCIES GREATER THAN  BANDWIDTH OF SEVERAL '(Z ON TRANSMIT AND ALMOST TWICE THAT BANDWIDTH ON  RECEIVE PHASE AND AMPLITUDE CALIBRATION AND CONTROL ADEQUATE TO PROVIDE AT LEAST n D"  RMS SIDELOBES AMPLITUDE CONTROL ADEQUATE TO PROVIDE  D" POWER MANAGEMENT NOISE PERFORMANCE ADEQUATE TO SUPPORT THE SUBCLUTTER VISIBILITY REQUIREMENTS AND FINALLY  SUF 
 Although there is  much that is known about the nature of sea clutter, the quantitative, and sometimes even t11c  qualitative, effects of many of the above factors are not known to the degree often desired. The  relative uniformity of the sea over the oceans of the world makes it easier to deal with sea  clutter than with land clutter, but it is difficult to collect data at sea under the controlled and  reproducible conditions necessary to establish quantitative causal relationships. In spite of the  limitations, there does exist a body of information regarding the radar echo from the sea, somc  of which will be reviewed briefly in this section. 
 TER MOUNTED OFF THE GIMBAL VERSUS A REAL 
 Ê, ,, 
 INTERVAL RATIO . 
 SQUARED ANTENNA PATTERN  WHERE THE ECHO IS INDE 
  " - 2ADAR BEACONS HAVE PLAYED AN IMPORTANT ROLE IN MARINE NAVIGATION EVER SINCE THE EARLY DAYS OF RADAR 4HEY BASICALLY DETECT INCIDENT PULSES FROM MARINE RADARS AND INSTAN 
 It is clear, therefore, that  the doppler spectrum contains the information necessary to measure meteorologically  important signal parameters. These first three moments are usually referred to as base  data and often labeled Z, V, and W with the appropriate conversions and units. In the most general case, quadrature phase detection is used to obtain the real and  imaginary parts of the complex signal. 
 Fishwick: Analog Waveform Generation and Processing, Electronic Progress,  vol. 17, no. 1, pp; 2-16, Spring, 1975. 
 For present purposes it will be  assumed that the aperture extends in one dimension only. This might represent the distribution  across a line source or the distribution in one plane of a rectangular aperture. If the constant  230INTRODUCTION TORADAR SYSTEMS whereIA(z)I=amplitude distribution and'P(z)=phasedistribution. 
 When high power is required, the klystron tends to be preferred  over the TWT since it doesn’t experience the stability problems of the TWT. Gilmour14 gives the mean time between failures (MTBF) for nine different types  of coupled-cavity TWTs as varying from 17,800 hours to 2,200 hours, with an aver - age of 7,000 hours for all nine classes of tubes. (He also says that TWTs for space  application, which are of lower power than radar TWTs, have MTBFs of the order of  one million hours.) Depressed Collector. 
 This iscertainly anoverestimate because the mountain will generally not have unity reflection coefficient, and because the part ofthe model that does the reflecting-namely, the part ofthe hemisphere normal to the line ofsight—will usually bemissing inactuality. Nevertheless, thecalculation isinteresting asindicating that oery large ground returns arepossible. Asecond estimate can bederived from measurements made atEllen- ville, N.Y.with amore orless normal (l-psec, 100-kw) pulse system. 
 Nathanson, F. E., "Radar Design Principles," McGraw-Hill Book Company, New York, 1969. 117. 
 69, no. 24,   pp. 5181–5190, 1964. 
 For the case where the  transmit and reference waveform LFM slopes are equal ( a  = a R), the IF signal is an  uncoded pulse with frequency offset given by  δ α τ τ f fd R= + −( )  (8.29) The frequency offset is measured using spectrum analysis and converted to target  time delay and range relative to the reference waveform by  ∆ ∆ ∆τ τ τδ α τ= − = − = − =Rf r R Rc( )02 (8.30) where R0 = ctR/2 is the range corresponding to the time delay of the reference waveform.  Kellog65 describes additional considerations for application of time-domain  weighting in stretch processing and provides details on compensation techniques for  hardware errors. The effect of time mismatch between the signal and the weighting  function is analyzed by Temes.66 ch08.indd   33 12/20/07   12:51:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 16.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Ground and Helicopter Scatterometers and Spectrometers.  Many ground  scattering measurements have been made with systems mounted on boom trucks  and helicopters. Most of these are FM-CW systems94,95 that use wide bandwidth to  obtain extra independent samples rather than for fine resolution. 
 TO 
 TRAIN CONSTEL 
 Methods ofAFC inpulse radar practice are quite different from those ofradio ortelevision; inradar, frequency control isexerted bypassing aportion ofthe transmitted signal through amixer and i-f amplifier, and maximizing itsintensity bythe use ofafrequency dis- criminator and electrical circuits, which tune thelocal oscillator. When theradar istorespond tobeacon signals, thereceiver must be tuned tothe beacon transmitter rather than tothe local one. Inthis case, analternate local oscillator (not shown inFig. 
 DOPPLER CELL  THE  0D AS A FUNCTION OF 3.2 FOR A -ARCUM NONFLUCTUATING  TARGET  CAN BE APPROXIMATED AS  00 . 0 0D        LN;   = 3.2 ERFC&! PDI &! &! 
 Figure 12.19 shows an example64 based on the theoretical scattering coeffi- cient for the sea derived from the spectra reported by the Stereo Wave Observa- tion Project.65 The effect of different beamwidths is clearly shown. With a pulse or other range-measuring system, reported values are always in error because, as indicated above, it is almost impossible to resolve a narrow range of angles near the vertical. Ground and Helicopter Scatterometers and Spectrometers. 
 Personnel shouldneverlookintoanopen waveguide orantenna feedhornconnected toenergized transmitters. Whenpersonnel mllst workinareaswherethepower·density isatadangerous level,theyshouldbeprotected with screened enclosures orwithprotective apparelmadefromreflective material. Another potential safetyhazardinworking withhighpoweristhegeneration ofXrays whenhighvoltages areusedtooperai~RFpowertubes.Tubesmustbe-properly shielded with lead,andX-raysafetybadgeswornbyoperating personnel towarnofexcessive dosage. 
 Geophys. Res. Solid Earth 2012 ,117.[CrossRef ] 27. 
 ,- 4HE AVAILABILITY OF HIGH 
 1975.  89. Trunk, G. 
 S. L. Johnston, “World War II ECCM history,” suppl. 
 Any use is subject to the Terms of Use as given at the website. Meteorological Radar.  METEOROLOGICAL RADAR  19.376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 and an effort beginning a decade later continued the development of phased array  radars for civil applications.166 Radars initially designed for military applications  were modified for weather detection and successfully demonstrated the concept.167 In  the early 2000s, a joint effort between the U.S. Navy, the National Weather Service,  the National Severe Storms Laboratory, and the University of Oklahoma led to the  development of the so-called National Weather Radar Testbed facility in Norman,  Oklahoma, by combining a single panel SPY-1 phased array radar on a rotating pedes - tal with a WSR-88D transmitter and custom receiver.168 Although this particular radar  is not likely to be the preferred design for a future weather radar, the Oklahoma Phased  Array Radar testbed can be used to explore electronic scanning strategies together with  new pulsing and processing concepts that may lead to future development of a phased  array weather radar system. 
  (IGH 02&  
 (b) FIG. 24.27 (Continued) (b) Target, clutter peaks, and noise are plotted ver- sus time for a longer sequence of data as in a.(c) FIG. 24.27 (Continued) (c) Amplitude distributions of target, clutter peaks, and noise are plotted.CUMULATIVE PROBABILITY - NORMAL DISTRIBUTION TIME . 
 7.9RADOMES 14,103,115,122-124 Antennas forground-based radarsareoftensubjected tohighwinds,icing,and/ortemperature extremes. Theymustbesheltered iftheyaretocontinue tosurviveandperform underadvase weather conditions. Antennas whichmustbeoperated insevereweather areusuallyenclosed forprotection inasheltering structure calledaradome.Radomes mustbemechanically strong iftheyaretoprovidethenecessary protection, yettheymustnotinterfere withthenormal operation oftheantenna. 
 10.8 MODULATORS This section briefly reviews the modulator,  sometimes called the pulser,  which is the  device that turns the transmitter tube on and off to generate the desired pulse wave - form. Those desiring more information might examine Chapter 9 in L. Sivan’s book  on transmitters,47 the chapter by T. 
 Toups, and M. A. Worris,  “Foliage penetration experiment,” (series of three papers), IEEE Transactions on Aerospace  and Electronic Systems , vol. 
 13-14, October, 1959.  51. Hogg, D. 
 7'111:  .preferred frequency for a ground-based aircraft surveillance radar is at the lower portion of the  ~~iicrowave region (UHF or L band). The major factors of importance that favor the lower  frequencies for surveillance radar are ttie large average power and the large antenna aperture.  both of which are easier to obtain at the lower frequencies. 
 The solid circles are the averages over a ir 20" sector around the broadside  aspect.g2 The x's are the average of the +20° head-on and +20° tail-on aspects.92993 (Note  that the values given for the pigeon in Fig. 13.10 differ from those given in Table 13.3. The two  sets of values are from diflerent sources.)  The radar cross section of birds does not show a simple wavelength or size dependen~e.~'  There are resonant effects, as illustrated by the measured cross section of a 21-lb duck at UliF  being nearly twice that of a 4&-lb (The median value of the 4a-lb duck head-on was  600 cm2, and 24 cm2 tail-on.) The backscatter from birds fluctuates over quite large values  with the maximum and minimum differing at times by more than two orders of magnitude  'Thus it is difficult to describe the radar cross section by a single value. 
 The assessment system requirements included modeling all natural environmental  effects, being quickly executable, and executing on a Microsoft Windows operating  system personal computer. An evaluation of the various propagation models for their  strengths and weaknesses quickly showed that a hybrid model was the only accept - able solution. The AREPS graphical user interface was created and interfaced to the  APM to provide the user an end-to-end radar propagation assessment tool. 
 UES OF 3.2 AND *.2 4HE DESIGN PARAMETERS CAN BE SELECTED BY TRYING TO MAXIMIZE THE DETECTION PROBABILITY  0 $ WHILE KEEPING AT PRESCRIBED VALUES THE PROBABILITIES  0" AND  0&! AND TRYING TO MINIMIZE  0&4  04"  AND , 4HE CHOICE OF THE POSITION OF THE AUXILIARY  ANTENNA HAS AN IMPACT ON 3," PERFORMANCE IN PRESENCE  FOR INSTANCE  OF MULTIPATH TO AVOID ITS EFFECT  THE PHASE CENTERS OF MAIN AND AUXILIARY ANTENNAS SHOULD BE POSITIONED AT THE SAME HEIGHT WITH RESPECT TO THE TERRAIN SURFACE )N MODERN RADAR  THE BLANKING OF SIDELOBE IMPULSIVE INTERFERENCE MAY BE ACHIEVED  BY THE COMPARISON OF SIGNALS  PERTAINING TO THE SAME CELLS OF THE RANGE 
 and fused quart z.The principal factors encountered inline design have been treated indetail elsewhere’ and will bebriefly reviewed here. LiquidLines.—The simplest delay line isastraight tube with parallel transducers atthe end. Alaboratory design ofmercury line has been shown inFig. 
 102–107, October 1984. 87. H. 
 SCALE RANGE ACCURACY IS SUPPORTED IN THE OCEANOGRAPHIC APPLICATION  BY AVERAGING OVER THE RANGE RESPONSE OF MANY RETURNS 4HE RANGE  RESOLUTION OF EACH  RETURN WAVEFORM IS TYPICALLY ON THE ORDER OF  METERS 4HESE WAVEFORMS ARE ACCU 
    
 38, pp. 1 197-1203, October, 1950.  15. 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.66  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 50. M. 
 The 2nd to the Kth Azimuth Sidelobes in Elevation Must Be Outside the Integrating Range [−h,h] kis a number we select. With the increase of k, the performance of azimuth sidelobes suppression is better. Two cases need to be considered: (a) if the kth azimuth sidelobes is not aliased in elevation, it will be outside [−h,h]when (17) is satisﬁed, since y/prime kcotα/sinθ−0.5ρe≥y/prime 1cotα/sinθ−0.5ρe, where y/prime k=kρa; (b) if the kth azimuth sidelobes are aliased in elevation, the following conditions must be satisﬁed: ⎭braceleftBigg y/prime k+1=(k+1)ρa y/prime k+1cotα/sinθ+0.5ρe≤Hmax−h, (18) Hence, Bcosα≤λr(2N−1)/(4(k+1.5)Nρa). 
 (4.6)] consists of a cosine wave at the doppler frequency f4 with an amplitude  2k sin nf, T: Thus the amplitude of the canceled video output is a function of the doppler  frequency shift and the pulse-repetition interval, or prf. The magnitude of the relative  frequency-response of the delay-line canceler [ratio of the amplitude of the output from the  delay-line canceler, 2k sin (nf.t T), to the amplitude of the normal radar video k] is shown in  Fig. 4.7. 
 TIPATH REFLECTIONS FROM THE GROUND  KNOWN AS HOT 
 D" INCREASE BECAUSE THE OSCILLATOR CONTRIBUTES NOISE DURING BOTH TRANSMITTING AND RECEIVING 4HIRD  ADJUST THE OSCILLATOR PHASE NOISE SPECTRAL DENSITY DETERMINED ABOVE DUE TO THE FOLLOWING THREE EFFECTS  A  THE SELF 
 % ORIGINALLY DEVELOPED BY 6ARIAN !SSOCIATES  )NC  IS A  
 Parameters of near-ﬁeld InISAR test system. Parameter Parameter V alue Carrier frequency 10 GHz Bandwidth 4 GHz Frequency step interval 40 MHz Azimuth accumulation angle 20◦ Azimuth sampling interval 0.2◦ Distance between antenna and target 0.02 m Baseline length 2 m The parameter calculation rules are as follows: (1) Antenna baseline Height information of the target is mainly calculated by phase difference of dual-antenna propagation path. In general, the interferometric phase difference is a periodic function for the period with 2 π. 
 The speed, course, and maneuver of a  target can indicate something about its intent; and therefore a form of target classification is  possible. Automatic detection and tracking circuitry can aid in this form of discrimination  since it provides a method for obtaining the target track. The long-range capability of HF  over-the-horizon radar (Sec. 
 368 INTRODUCTION TO RADAR SYSTEMS  55. Reynolds, J. F., and M. 
 ARRAY OUTPUTS BECAUSE OF THE DIFFERENT NUMBER OF ELEMENTS IN EACH SUB 
 Figure 2.77 shows the spectral modifications due to the system responses: ( a) The  first modification accounts for correlation due to the range to the clutter of interest  [assumed clutter range is ≈ 50 nmi (92.6 km); thus, the break frequency is 365 Hz].  (b) Second, a three-pulse binomial-weighted canceler is assumed with the radar operat - ing at a PRF of 360 Hz. Thus, the break frequency is 0.249 × 360 = 90 Hz. 
 217-288.  91. Shelton, J. 
  
 33.Nathanson, F.E.:"Radar DesignPrinciples," McGraw-Hill BookCo.,NewYork,1969. 34.Rihaczek, A.W.:RadarWaveform Selection-A Simplified Approach, IEEETrans.,vol.AES-7,pp. 1078-1086, November. 
 It would perform  more efficiently than a detector 'Yhich .used either amplitude information only or phase infor­ mation only. The coherent detector is an example of one which uses both phase and amplitude.  These three types of detectors-the envelope, the zero-crossings, and the coherent detectors­ are considered in the present section ... 
 TION OF FALSE TRACKS  WHICHFROM A TACTICAL PERSPECTIVECAN CAUSE SERIOUS DILEMMAS FOR A RADAR OPERATOR 4HIRD  THERE ARE THE ADAPTIVE #&!2 DETECTORS !-&  OR ADAPTIVE MATCHED FILTER   FOR EXAMPLE   THAT REALLY ARE %##- TECHNIQUES IN THE SENSE THAT THEY ENHANCE THE  PROBABILITY OF DETECTION AGAINST STRUCTURED INTERFERENCES IN SPACE ANDOR TIME  WHILE MAINTAINING THE CONSTANT FALSE ALARM RATE PROPERTY THAT ALLOWS THESE DETECTED TARGETS TO BE EFFECTIVELY TRACKED  RATHER THAN BEING SEDUCED BY A HIGH NUMBER OF FALSE DETECTIONS 4HIS TYPE OF PROCESSINGOR SIMILARLY DERIVED FROM THE GENERALIZED LIKELIHOOD RATIO TEST ',24 HAS BEEN USED IN SOME PRACTICAL RADAR &URTHERMORE  ANY SELF 
 - ,*/" -ÊEÊ76 
 ARI 5136 with common T & R [ 8].Airborne Maritime Surveillance Radar, Volume 1 2-17. that presented a short-circuit when excited. On transmit, the two spark gaps would ﬁre and the path from transmitter to receiver, shown in ﬁgure 2.19(a), would appear open circuit when viewed from the transmitter, with a low impedance towards the antennas. 
 Levit, S. Stefanini, and L. Timmoneri, “Multi- channel radar: Advanced implementation technology and experimental results,” Proc. 
 OFF CONTINUES APPROXI 
 The other method uses a ferrite circulator to separate the transmitter  and receiver, and a receiver protector consisting of a gas TR-tube and diode limiter.  .J  Branch-type duplexers. The branch-type duplexer, diagrammed in Fig. 
 For example, in a  proper sea clutter measurement, the polarization, radar frequency, grazing angle, and  resolution cell size will have been specified. Then the wind speed and direction must  be measured at a reference altitude, and if the results are to be compared with those  of other experimenters, the proper duration  and fetch  should be available to ensure  standardization to equilibrium sea conditions. Since these measured winds are related  to the wind structure at the surface through the atmospheric boundary layer, the shape  of this layer must be determined by measuring the air and sea temperatures. 
 -Sections 3.12 to3.16 have been devoted todis- cussions ofthe kinds oftargets and target contrasts encountered with airborne radar. Itremains todescribe their integration into the radar picture asawhole and theuse ofthis picture asanavigational aid. A fullerdiscussionof this subject will befound invol. 
 Integration can also be performed after detection. In fact postdetection inte- gration is used more commonly than is predetection integration, for reasons that will be explained, but the analysis of the resulting improvement is then much more complicated. After detection, the signals and the noise cannot be regarded as totally separate entities; the nonlinear process of detection produces an insep- arable combination of signal and noise, so that one must then consider the com- parison of signal-plus-noise to noise. 
 TRIP  ILLUMINATION FUNCTION  4HUS  THE BEAMWIDTH OF THE ECHO RESPONSE OF A FLAT PLATE IS HALF THE BEAMWIDTH OF AN ANTENNA APERTURE OF THE SAME SIZE 4HE PROMINENT LOBE IN THE HORIZONTAL PATTERN IN THE REGION BETWEEN n AND n IS DUE TO A SURFACE TRAVELING WAVE )N CONTRAST TO THE PATTERN OF A FLAT PLATE  THE 2#3 PATTERN OF A CORNER REFLECTOR IS QUITE  BROAD 4HIS IS BECAUSE THE CORNER REFLECTOR IS A REENTRANT STRUCTURE  AND NO MATTER WHAT ITS ORIENTATION WITHIN LIMITS  OF COURSE   INTERNALLY REFLECTED WAVES ARE DIRECTED BACK TOWARD THE SOURCE OF THE INCIDENT WAVE ! CORNER REFLECTOR IS FORMED BY TWO OR THREE FLAT PLATES INTERSECTING AT RIGHT ANGLES  AND WAVES IMPINGING ON THE FIRST FACE ARE REFLECTED ONTO THE SECOND IF THERE IS A THIRD FACE  IT RECEIVES WAVES REFLECTED BY THE FIRST TWO FACES 4HE MUTUAL ORTHOGONALITY OF THE FACES ENSURES THAT THE DIRECTION TAKEN BY WAVES UPON FINAL REFLECTION IS BACK TOWARD THE SOURCE 4HE INDIVIDUAL FACES OF THE CORNER REFLECTOR MAY BE OF ARBITRARY SHAPE  BUT THE MOST  COMMON IS AN ISOSCELES TRIANGLE FOR THE TRIHEDRAL CORNER DIHEDRAL CORNERS TYPICALLY HAVE RECTANGULAR FACES 4HE 2#3 OF A CORNER REFLECTOR SEEN ALONG ITS AXIS OF SYMMETRY &)'52%  2#3 OF A SQUARE FLAT PLATE  
 (1.1)2INTRODUCTION TORADAR SYSTEMS Thenameradarreflectstheemphasis placedbytheearlyexperimenters onadeviceto detectthepresence ofatargetandmeasure itsrange.Radarisacontraction ofthewordsradio detection andranging.Itwasfirstdeveloped asadetection devicetowarnoftheapproach of hostileaircraftandfordirecting antiaircraft weapons. Although awell-designed modernradar canusuallyextractmoreinformation fromthetargetsignalthanmerelyrange, the measure­ mentofrangeisstilloneofradar'smostimportant functions. Thereseemtobenoother competitive techniques whichcanmeasure rangeaswellorasrapidlyascanaradar. 
 Afraction ofthetransmitler powerincident ontheTRtubeisabsorbed bythedischarge. Thisiscalledarcloss.Itsmagnitude depends uponthecharacteristics oftheinputwindowand thegasused.Thearclossmightbe';to1dBintubesfilledwithwatervaporand0.1dBorless withargonfilling.Onreception, theTRtubeintroduces aninsertion lossofabout!to1dB. Thelifeofaconventional TRislimitedbythekeep-alive, theamountofwatervaporin thegasfilling,andbydisappearance, or"clean-up," ofthegasduetothegasmolecules becoming imbedded inthewallsoftheTRtubes.41TheendoflifeofaTRtubeisdetermined morebytheamountofleakagepowerwhichitallowstopassthanbyphysical destruction or wear. 
 The power in each bin in a grid cell in the clear (thermal noise  limited) region is compared to a threshold, PTH1(EA), which is a function of the EA  in that grid cell. In the endoclutter near sidelobe region, a discriminant, Cs, is formed  and used to provide additional clutter cancellation prior to thresholding. Again, the  threshold, PTH2(EA), is a function of the EA in that grid cell and a priori knowledge of  the clutter statistics. 
 The integration can always take place at two different places in the signal  path:   - IF Integration   ⇒ Pre-dete ction or Coherent integration,   - Video Integration  ⇒ Post-detection or Incoherent integration.   Coherent integration (pre -detection) is only seldom used, since it assumes a constant phase  between transmission and receiving for the pulses to be integrated.  The integration can then,  for example, take place through a narrow IF filter, whose bandwidth is inversely proportional  to the target dwell time. 
 If the top of an elevated object, such as a  tower, is on the layover circle and if the ground is flat, then the top of the tower  will appear in the SAR image at the same position as a point on the ground where  the layover circle intersects the ground. The tower will be “laid over,” hence the  nomenclature. As shown in Figure 17.13, let us consider a platform in straight-line, constant-speed  motion at altitude H over a flat earth forming a SAR image, the center of which is at  slant range Rs  H and squint angle qsq. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers.  RADAR RECEIVERS  6.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 It should be noted that measurements of phase noise are typically performed by  measurement of double-sideband noise, the sum of the power in both the upper and  lower sidebands, but more typically reported and specified as single sideband (SSB)  values. 
 NATED PATCH SET BY THE CIRCULAR ANTENNA PATTERN BECOMES RATHER LONG THE PATCH IS AN ELLIPSE   AND USE OF THE PULSE LENGTH TO CONFINE ILLUMINATION TO A PART OF THE PATCH IS HELPFUL )NDEED  FOR ANGLES VERY NEAR GRAZING  THIS IS THE ONLY SATISFACTORY WAY TO RESOLVE SMALL REGIONS -ANY SYSTEMS THAT USE BEAMWIDTH TO SET THE MEASURED AREA NEAR VERTICAL USE RANGE RESOLUTION FOR ANGLES BEYOND  SAY   &)'52%     2ANGE RESOLUTION APPLIED TO SCATTEROMETRY  A  IMPROVING ONE DIMENSION OF A    CIRCULAR 
 BEAM CLUTTER TIME FLUCTUATION STATISTICS ARE HIGHLY DEPENDENT ON THE TYPE OF CLUTTER BEING OBSERVED  SUCH AS SEA CLUTTER OR CLUTTER FROM AN URBAN AREA  AND ARE GENERALLY UNKNOWN  A VALUE OF  TO  D" ABOVE THE RMS VALUE IS OFTEN ASSUMED FOR THE MAXIMUM PEAK LEVEL THIS ALSO INCLUDES THE  D" DIFFERENCE BETWEEN THE RMS AND PEAK VALUES OF A SINUSOIDAL SIGNAL  4HUS  THE REQUIRED NUMBER OF AMPLITUDE BITS IN THE !$ CONVERTER AS DETERMINED BY THE MAIN 
 TRACKING SYSTEM PERFORMS THE TASK OF KEEPING  THE GATE CENTERED ON  THE TARGET ECHO  AS DESCRIBED IN 3ECTION  4HE PRIMARY OUTPUT OF TRACKING RADAR IS THE TARGET LOCATION DETERMINED FROM THE  POINTING ANGLES OF THE BEAM AND POSITION OF ITS RANGE 
 (ILL "OOK #OMPANY      PP n  n   * 2HEINSTEIN  h"ACKSCATTER FROM SPHERES ! SHORT 
 25 of" Radar Handbook," M. 1. Skolnik (ed.). 
 The amount of isolation required depends on the transmitter power and the accompany­ ing transmitter noise as well as the ruggedness and the sensitivity of the receiver. For example,  if the safe value of power which might be applied to a receiver were 10 mW and if the  transmitter power were l kW, the isolation between transmitter and receiver must be at least  50 dB.  The amount of isolation needed in a long-range CW radar is more often determined by . 
 , Melbourne, Austrailia, 1985,  pp. 853–856. 64. 
 SUPPORT  OR  COOPERATIVE  %#- INVOLVES THE COORDINATED CONDUCT OF %#-  BY COMBAT ELEMENTS AGAINST ACQUISITION AND WEAPON CONTROL RADARS /NE ADVANTAGE OF MUTUAL 
 In the step-scan antenna it has been suggested that the  undesirable transient effects can.be mitigated by using the initial return from each new beam  position, or an average of the first few returns, to apply initial conditions to the MTI filter for  processing the remaining returns from that position.15 The clutter returns can be approxi­ mated by a step-input equal in magnitude to the first return for that beam position so that the  steady-state values that would normally appear in the filter memory elements after an  infinitely long sequence of these inputs can be immediately calculated and loaded into the filter  to suppress the transient response.  Although the undesirable transient effects of a recursive filter can be reduced to some  extent, other approaches to MTI filtering are often desired. One alternative the designer has  available is the use of multiple pulse-repetition frequencies for achieving the desired MTI filter  characteristics, as described next. 
 This nonlinearity reduces con- siderably the difference involtage between those signals that are just strong enough toproduce avisible result and the level at,which strong signals must belimited. Itispossible tointroduce anonlinear element inthevideo amplifier tocompensate forthetube characteristic, and this has been done with some success. Noreally satisfactory circuit ofthis sort has been devised, nodoubt because theneed foritwas fully appre- ciated only recently. 
 Aircraft and ground  vehicular traffic at large airports arc monitored by means of high-resolution radar. Radar  has been used with GCA (ground-control approach) systems to guide aircraft to a safe  landing in bad weather. In addition, the microwave landing system and the widely used  A TC radar-beacon system are based in large part on radar technology. 
 THE 
 conversion down to IF, and diode mixers are most commonly employed. The frequency-conversion properties of the diode are produced by its nonlinear charac- teristics. If its characteristic is defined by a power series, only the square-law term produces the desired conversion. 
 TH SUB 
 Meyer, F.J. Performance requirements for ionospheric correction of low-frequency SAR data. IEEE T rans. 
 BEAM TUBES ARE APPROXIMATELY COMPARABLE 4HERE ALSO HAVE BEEN  HYBRIDS OF THE KLYSTRON AND THE 474 THAT HAVE BEEN OF INTEREST  FOR RADAR APPLICATIONS  AND WHICH HAVE INTERESTING CHARACTERISTICS 4HE CROSSED 
 One of the features of the first edition which has been continued is the inclusion of  extensive references at the end of each chapter. These are provided to acknowledge the sources  or material used in the preparation of the book, as well as to permit the interested reader to  learn more about some particular subject. Some references that appeared in the first edition  have been omitted since they have been replaced by more current references or appear in  publications that are increasingly difficult to find. 
 This criterion, or its equivalent, is used for the  design of almost all radar receivers.  The frequency-response function, denoted H( f ), expresses the relative amplitude and  phase of the output of a network with respect to the input when the input is a pure sinusoid.  The magnitude I H( f) I of the frequency-response function is the receiver amplitude passband  characteristic. 
 The current can beincreased. SEC. 13.6] AMPLIFIERS 495 byusing asmaller value ofRk,which sacrifices gain, orbyusing a positive grid bias. 
 TO 
 Good results have been obtained bypowering theradar system from a 60-cycle motor-generator set. Aninduction motor isused todrive the alternator; when not heavily loaded, themot orshows arelatively small change inspeed for achange ininput voltage. Motor speed tends tofollow achange infrequency, but themechanical inertia ofthe setis usually adequate tohold upthe speed during the usual short-period frequency transients. 
 24. J. G. 
 Multiple-Parameter Radar. It has been noted earlier that doppler radar provides a significant increase in the useful information that can be obtained from meteorological targets. The detection of hail, through the use of polarization diversity, adds additional information, and multiple wavelength provides yet another input related to the eventual interpretation of the size, water-phase state, and types of hydrometeors in all classes of clouds and precipitation. 
   SO THE PLANFORM NOSE ANGLE SEEMS TO BE A COMPROMISE BETWEEN THE TWO .OTE THAT THE ABSENCE OF A COCKPIT IMPROVES THE STEALTHINESS OF THE AIRFRAME )NDEED  THE ENGINE INLET COWLING REPLACES THE COCKPIT  AND EVEN THE LIPS OF THE INLET ARE BROADLY SERRATED TO REDUCE THEIR CONTRIBUTION TO THE RADAR ECHO 4HE LACK OF ANY TAILFIN AND THE CONTOUR OF THE TRAILING EDGES OF THE PLANFORM REVEAL STRONG INFLUENCES FROM THE " 
 NAVIGATION !TO.  HAS BEEN PUT FORWARD AS A POSSIBLE  REPLACEMENT FOR RACONS  WHICH ARE DESCRIBED IN THE NEXT SECTION )N PRINCIPLE  !)3 !TO.S COULD REPLACE RACONS  BUT IN PRACTICE  IT WOULD BE A RETROGRADE STEP AS THEY CANNOT BE USED INDEPENDENTLY OF A POSITION FIX SYSTEM  SUCH AS '.33 (OWEVER  THEY CAN BE USEFULLY EMPLOYED TO INDICATE THE INTEGRITY OF THE ACTUAL POSITION OF THE MARK  WHICH MAY HAVE DRAGGED OR BECOME UNATTACHED  AND OTHER ADDITIONAL DATA  SUCH AS SEA CURRENTS 4HE !)3 TRANSCEIVER DOES NOT HAVE TO BE SITUATED ON THE ACTUAL MARK AND COULD BE SHORE 
 TYPE MODULATOR )T CAN  PROVIDE EXCELLENT PULSE SHAPE  VARYING PULSE DURATIONS  AND PULSE REPETITION FREQUEN 
 DICTABLE MONOSTATIC WORLD ! RELATED MODULATION CONTENT PROBLEM IS  DEAD AIR  WHERE NO INFORMATION IS BROAD 
 B. A. M. 
 When clutter sup - pression is to be implemented with a single MTI filter, it is necessary to use adaptive  techniques to ensure that the clutter falls in the MTI rejection notch. An example of  such an adaptive MTI is TACCAR,31 originally developed for airborne radars. In many  applications, the adaptive MTI will further have to take into account the situation  where multiple clutter sources with different radial velocities are present at the same  range and bearing. 
 DIMENSIONAL %- INTENSITY IMAGE OF MOVING TARGETS EG  SHIPS  AIRCRAFT  IN THE RANGE AND CROSS 
 Thesemeasurements weremadeinGeorgia duringthesummer andfallmonths andincluded deciduous treesandpinetrees.Thegrazingangleswerefrom2to25°.Thepulse widthwas.100nsandtheantenna beamwidth wasinthevicinityofonedegree. Thevalueof0-0forseaclutteratlowgrazingangleandlowwindshasbeenreported 76to ..notincrease withfrequency muchaboveXband,"butalso77the"trendofincreasing reflectivity withdecreasing wavelength alsoholdsforseaclutteralthough theeffectisnot nearlyaspronounced asforlandclutter." However, bothreferences statethatforhighersea states(themaximum windspeedwas14knots)thevalueof0-0at94GHzislessthanthatatX hand.Another observation isthatverticalpolarization seemstoproduce lowervaluesof0-0at. 94 GHz by about 5 dB (on average) than horizontal polarization, which is the opposite to the  experience at microwaves. 
 K.: "CW and Doppler Radars," vol. 7, Artech House, Norwood, Mass., 1978, sec. IV-I, pp. 
 Laing: Point-Scatterer Formulation of Terrain Clutter Statistics, Narsal  Resi~orclt Luhoratory Report 7459, Sept. 27, 1972, Washington, D.C.  45. 
 898-903, May, 1960.  47. Blake, L. 
 SEC. 6.14] PRECISION TRACKING OF ASINGLE TARGET 203 satisfactory way bytheAIA equipment and itsredesigned successor, the AN/APS-6. This 3-cm equipment has an 18-in. 
 Just as is done in antenna design, the filter sidelobe can be reduced by  using Chebyshev, Taylor, sin2 x/x2, or other weightings.39 (In the digital signal processing  literature, filter weighting is called windowing.80 Two popular forms of windows are the  Hamming and hanning.) It may not be convenient to display the outputs of all the doppler  filters of the filter bank. One approach is to connect the output of the filters to a greatest-a,(  circuit so that only a single output is obtained, that of the largest signal. (The filter at de which  contains clutter would not be included.)  the improvement factor for each of the 8 filters of an 8-pulse filter bank is shown in  Fig. 
 CAVITY KLYSTRON !T THE LEFT IS THE  HEATER THAT HEATS THE CATHODE AND THE  CATHODE THAT EMITS A STREAM OF ELECTRONS THAT ARE  COLLIMATED INTO A NARROW CYLINDRICAL BEAM OF HIGH ELECTRON DENS ITY 4HE ELECTRON GUN  THAT GENERATES THE BEAM CONSISTS OF THE  CATHODE  THE  MODULATING ANODE ALSO CALLED  THE BEAM CONTROL GRID     AND THE  ANODE 4HE MODULATING ANODE PROVIDES THE MEANS TO  PULSE THE ELECTRON BEAM ON  AND OFF 4HE  2& CAVITIES ARE THE MICROWAVE EQUIVALENT OF  A RESONANT CIRCUIT %LECTRONS ARE NOT INTENTIONALLY COLLECTED AT THE ANODE AS THEY ARE IN GRID 
 Visual observa - tion and radar remain the primary methods for determining the risk of collision with  other vessels and also with floating debris and ice. Automatic Identification Systems  (AIS—see Section 22.7) offer potential to assist with collision avoidance of coopera - tive targets, but it cannot be assumed that all vessels are fitted with AIS, particularly  small craft, or that a target vessel’s AIS is operational. The traditional way for mariners to optimize their radar for detection of targets in sea  clutter is by careful adjustment of the “gain” and “sea-clutter” controls. 
 Angle ^ 1 deg.* = NoiseOCT SSN = 10 TIME = 18 GMTLOCATION 38.65 N LAT 76.53 W LON BEARING= 90.00 DEGOCT SSN = 100 TIME = 18 GMTLOCATION 38.65 N LAT 76.53 W LON BEARING= 90.00 DEG FIG. 24.26 Radar performance estimate; October, 1800 UTC. (a) SSN = 10. 
 £Ó°Î{  2!$!2 (!.$"//+  /35 CODES SUCH AS .%# 
 This rest~lts in  more accurate relative-velocity measurements with millimeter wavelengths than at lower  frequencies. The large doppler shifts at millimeter wavelengths, however, can sometimes result  in the echo signal being outside the receiver bandwidth, which complicates the receiver design.  Also, the large doppler frequencies at millimeter wavelengths cause the blind speeds of MTI  radars to appear at lower velocities than at microwaves, an undesirable property. 
 SEC, 153] INITIAL PLANNING AND OBJECTIVES 593 output pulse powers were then low, receiver sensitivities were poor, and system problems were notwell understood. Coverage equal toorbetter then that provided bythe longer-wave equipment then inuse orunder development appeared tobeattainable only bymeans ofextremely high antenna gain. Asthese ideas developed, microwave techniques were rapidly advanc- ing. 
 Although theabovearelimitations tothephased arr~yinradar,theyareprobably not sufficiently serioustorestrictitsgreateruse.However, themajorlimitation thathaslimitedthe widespread useoftheconventional phasedarrayinradarisitshighcost,whichisdueinlarge parttoitscomplexity. Thesoftware forthecomputer systemthatisneededtoutilizethe inherent flexibility ofthearrayradaralsocontributes significantly tothesystemcostand complexity. Oneofthefactorsthatisoftenmisleading istheusualpictureofanarrayasasingle radiatingfaceofrelatively modestsize.Asinglearrayantenna canscanbutalimitedsector; ±45°ineachplaneisperhaps typical.Fourormorefacesmighttherefore benecessary for hemispherical coverage. 
  
  AIRCRAFT AND WAS DISPLAYED IN THE EARLY S ON A 53 !IR &ORCE WEB SITE  4HE # 
 RESOLUTION MEASUREMENTS 4HIS POWERFUL TECHNIQUE PERMITS THE USE OF A MOBILE PLATFORM  WHICH THEREFORE ALLOWS MEASUREMENTS OVER REGIONS NOT ACCESSIBLE BY GROUND 
 NAS LOOK AT THE SAME GROUND POINT AT THE SAME TIME AND THAT THE SIGNAL BE CORRELATED WITH KNOWN ANTENNA LOOK ANGLES &URTHERMORE  IT IS DIFFICULT TO KNOW THE POLARIZATION  AND THE EXACT SIZE AND SHAPE OF THE COMMON AREA ILLUMINATED BY THE ANTENNA BEAMS ARE SOMETIMES DIFFICULT TO DETERMINE &OR THIS REASON  FEW BISTATIC MEASUREMENTS FROM AIRCRAFT HAVE BEEN REPORTED IN THE LITERATURE  ,ABORATORY BISTATIC MEASUREMENTS HAVE BEEN MADE BY BOTH THE 7ATERWAYS  %XPERIMENT 3TATION AND 4HE /HIO 3TATE 5NIVERSITY  GROUPS USING ELECTROMAGNETIC  WAVES AND BY THE 5NIVERSITY OF +ANSAS GROUP USING ACOUSTIC WAVES "ISTATIC MEA 
 A set  of outputs is provided to the mission management computer function, including North- East-Down (NED) velocity errors and estimates of statistical accuracies. Sniff or Passive Listening.  Most modes have a precursor subprogram called  sniff, which looks for passive detections in a tentative operating channel before any  radar emissions in that channel. 
 Brookner, E.: "Radar Technology," Artech House, Norwood, Mass., 1980, pp. 5-59. 8. 
   4 S    S FOR TARGETS WITH ESTIMATED SPEED GREATER THAN  MS 
 The output of the phase detector is sampled  sequentially by the range gates. Each range gate opens in sequence just long enough to sample  the voltage of the video waveform corresponding to a different range interval in space. The  range gate acts as a switch or a gate which opens and closes at the proper time. 
 John Wiley and Sons. Inc.. New York, 1969. 
 Lab. Tech. Rept. 
 ELECTRONIC COUNTER-COUNTERMEASURES  24.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 The DRFM is the principal means to implement a deception jammer; the range-gate  stealer pulls the radar-tracking gate from the target position through the introduction  of a false target into the radar’s range-tracking circuits. A repeater jammer sends back  an amplified version of the signal received from the radar. The deception signal, being  stronger than the radar’s return signal, captures the range-tracking circuits. 
 The  fact that it would be considerably more difficult to get decent imagery successfully FIGURE 18.16  Details of Magellan ’s elliptical orbit, dominated by ∼37 minutes of  data take and 2 hours of data downlink during each 3.3-hour orbit period ( Graphic  courtesy of NASA ) ch18.indd   49 12/19/07   5:15:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 A typical packaged power tran- sistor has low input and output impedances that must be transformed up to higher level, usually 50 ohms. Thus, the typical amplifier design task must address both low-loss and inexpensive reactive impedance-transforming networks that can provide the proper source and load impedances to the transistor. The common medium for providing this function is a microstrip transmission line. 
 VIDE SIGNIFICANTLY HIGHER POWER OUTPUT AND EFFICIENCIES THAN SOLID 
 This page has been reformatted by Knovel to provide easier navigation. viii     Contents   2.7 Loss Factor s  ...........................................................  2.46  Antenna Pattern Loss  ........................................ 
  INTO THE 40 ORBIT  4/0%8 WAS MANEUVERED INTO A hTAN 
 Both a mean-level  Filter number 5 6 A 7 8 1 2 3 4 5  C  prf -1  /  A  prf -2  // L" A  Aircraft aliases True Figure 4.28 Detection of aircraft in  oircrof t - rain using two prf's with a doppler  veloclt y filter bank, illustrating the effect of  0 doppler foldover. (From M~ehe,~'  Radial velocity Courtesy IEEE.)  128INTRODUCTION TORADAR SYSTEMS ofthedoppler filter-bank. ThefastFourier transform algorithm isllsedtoimplement the doppler filter-bank. 
 DOPPLER FOR THREE OR  MORE MEASUREMENTS  AND HAS BEEN USED TO MEASURE THREE 
 POWER ARRAY PREDRIVER IS USED TO DRIVE  SUBARRAY DRIVER  AMPLIFIERS %ACH OF THESE POWER AMPLIFIERS PROVIDES ENOUGH 2& DRIVE FOR ALL  MOD 
 S. Hi!~ Jr.: A Two-step Sequential Procedure for Improving the Cumulative  Probability of Detection in Radars, IEEE Trans., vol. MIL-9, pp. 
 Module Characteristics. Performance data exists for modules that use GaAs MMIC technology in the 1- to 10-GHz frequency range. Animated interest in lightweight, adaptive array applications will continue to push this technology. 
 LOBES &IGURES  AND   FURTHER ILLUSTRATE THIS IMPACT 4H IS BLOCKAGE EFFECT CAN BE  MODELED AS A hHOLEv IN THE APERTURE THAT CAN BE REPRESENTED BY A BROAD PATTERN WITH  LESS GAIN 4HIS BLOCKAGE PATTERN IS SUBTRACTED FROM UNPERTURBED UNBLOCKED  APERTURE FIELDS  AS SHOWN IN &IGURE  4HE ASSOCIATED PATTERNS  WITH AND WITHOUT BLOCKAGE  ARE SHOWN IN &IGURE  4HE  ALTERNATING LARGE  SMALL  LARGE  AND SO ON  SIDELOBE PROGRESSION IS CHARACTERISTIC OF A BLOCKED APERTURE 3URFACE ,EAKAGE ,OSS  -ANY REFLECTOR SURFACES ARE DESIGNED WITH A GRID  A WIRE 
 Author Contributions: Conceptualization, B.K. and D.F.; methodology, B.K.; software, B.K.; validation, B.K. and D.F.; investigation, B.K.; data curation, D.F.; writing—original draft preparation, B.K.; writing—review and editing, D.F.; supervision, D.F.; project administration, D.F.; funding acquisition, D.F. 
 Deep nulls in elevation and poor  low-altitude coverage have been mentioned. The available spectral widths assigned to  radar at VHF are small so range resolution is often poor. The antenna beamwidths are  usually wider than at microwave frequencies, so there is poor resolution and accuracy  in angle. 
 It is difficult to  estimate this correction. The resolution cell is not likely to be completely fiiled at long range or  when the beam is viewing the edge of a precipitation cell. If the" bright band" (to be described  later) is within the radar resolution cell, the precipitation also will not be uniform. 
 The clutter-  reject ion filter is a bandpass filter whose bandwidth depends upon the extent of the expected  clutter spectrum.  MTlANDPULSEDOPPLER RADAR117 thesameweightings, butwith4interpulse periodsof-15percent, .,..,.5percent,+5percent, and+15percentofthefixedperiod.Theresponse atthefirstblindspeedofthefixedperiod waverorm isdownonly6.6dB. Adisadvantage ofthestaggered prfisitsinability tocancelsecond-time-around clutter echoes.Suchclutterdoesnotappearatthesamerangefrompulsetopulseandthusproduces uncanceled residue.Second-time-around clutterechoescanberemoved byuseofaconstant prf.providing thereispulse-to-pulse coherence asinthepoweramplifier formofMTI.The constant prfmightbe~ll1ployed onlyoverthoseangularsectorswheresecond-time-around clutterisexpected (asintheARSR-3 ofSec.14.3),orbychanging theprfeachtimethe antenna scanshalf-a-beamwidth (asintheMTDofSec.4.7),orbychanging theprfeveryscan period(rotation oftheantenna). 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing.  RADAR DIGITAL SIGNAL PROCESSING  25.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 sample rate. The sine and cosine signals from the NCO are then digitally multiplied  by the digitized IF signal. 
 The Sequential Observer permits a significant reduction in the average number of samples  (pulses) needed for making a decision. The improvement depends upon whether a signal is  present or not. If a signal is present, the average number of samples (or observations) required  for making a decision is significantly greater than when noise alone is present. 
 herent; their phases are different for each pulse transmitted. Only in the IF por- tion of the receiver is the desired echo from a stationary target coherent (a = constant, where a is the phase of the echo when the transmitter is turned on); virtually all the spurious outputs of the mixer are noncoherent and produce a fluctuating signal at IF. The only spurious component that may be coherent in the pseudo-coherent radar is the image frequency. 
 DENT ENERGY IN A DIFFERENT DIRECTION  AND TO THE EXTENT THAT GEOMETRIC OPTICS IS VALID  THE POWER DENSITY AT THAT ANGLE IS THE INTEGRATED SUM OF THE POWER DENSITY FROM THE FEED ACROSS THAT PORTION OF THE REFLECTOR 3ILVER  GRAPHICALLY DESCRIBES A PROCEDURE FOR  DETERMINING THE REFLECTOR CONTOUR FOR A COSECANT 
 Conditions in the South China Sea approximatethoseoffthesoutheasterncoastoftheUnitedStatesonlyduringthe winter months, when ducting can be expected. During the rest of theyear, the Asiatic monsoon modiﬁes the climate in this area, but noinformation is available on the prevalence of ducting during this time. Tradewinds in the Paciﬁc quite generally lead to the formation of rather low ductsover the open ocean. 
 12.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 Installation Is a Significant Mechanical Design Driver.  The platform is gen - erally a dominant mechanical design driver because it determines the environment  (thermal, vibration, etc.), and it typically drives the available size, weight, and power  (SWAP) for the radar and the reflector antenna. Table 12.3 provides a qualitative com - parison of typical design requirements and features for radar reflector antennas on  ground-based, ship-based, airborne, and spaceborne platforms. 
 The power unit and switching sequences for turning on and turning off the radar were controlled from the switch unit. 3.3.8 Setting up and operating the radar The sequence for switching on the radar was controlled by the operator using the switch unit. After switching on the main master switch, the operator would ﬁrst press the LT ON button, when the green lamp would light. 
 There are many variations to these basic approaches, and specific imple - mentations often utilize efficient approaches that minimize the number of calcula - tions required with emphasis on reducing the number of multiplications, as these  require significantly more resources than additions. Two techniques used to reduce  the FIR filter processing burden are multirate processing and polyphase filtering.13  The digital downconversion approach is shown in Figure 6.21 using multirate pro - cessing. The first FIR filter h1(n) provides sufficient reduction to prevent aliasing  in the first decimation by factor D1, the second filter h2(n) provides alias reduction  for the second decimation and can also be used to correct passband ripple or droop  due to filter h1(n). 
 MENT TO PROCESS THE PULSE )N MANY CASES  PULSE COMPRESSION CAN PROVIDE THE MEANS FOR EASY RADAR JAMMING FOR THE ENEMY %#- OPERATOR 0ULSE COMPRESSION IS ALSO VULNERABLE TO COVER 
 Although the vast majority of targets do  not scatter energy uniformly in all directions, the definition assumes that they do. This  permits one to calculate the scattered power density on the surface of a large sphere  of radius R centered on the scattering object. R is typically taken to be the range from  the radar to the target. 
 PERFORMANCE DIGITIZER  WHICH CAN RESULT IN CONSIDERABLE COST SAVINGS &IGURE A SHOWS THE SPECTRUM OF A MORE GENERAL COMPLEX SIGNAL OF BANDWIDTH  " BEFORE SAMPLING .OTE THAT THIS SIGNAL DOES NOT POSSESS COMPLEX 
 Detection RangeofSpaceSurveillance Chain.Aviation Week. Aug.16.1965. 28.Ismail.M.A.W.:AStudyoftheDoubleModulated FMRadar.Inst.Hock{requenztecll. 
 Inthese sets, the general mapping functions ofmicrowave radar have been sacrificed infavor oftheutmost simplicity and ease incarrying out thehoming function. FIG.6.31.—Scanner housing ofAN/APS-6 inwing ofF6F. Theinstallation ofAN/APS-3 iusingle-engine carrier-based tor~edo bombers isidentical inexternal appearance. 
 135 topermit theuseofhigher carrier frequencies than can readily bepassed through asynchro. Generators. —In some instances ofconical orspiral scanning, part of chescanner data isprovided bymeans ofad-cexcited 2-phase generator geared directly tothescanner axis. 
 BEAM PEAK GAIN TO CROSS 
 C. Levitt: Radar Range Performance, Hughes Aircraft Co. Tech. 
  AIRCRAFT  #OMBINING THESE HIGH 
 April,1960. ., ..,.. CW AND FREQUENCY-MODULATED RADAR 99  27. 
 298 ANTENNAS, SCANNERS, AND STABILIZATION [SEC. 9.15 bend EEnear theaperture has nooptical effect and was introduced for the sake ofcompactness. Aplastic closure prevents moisture from entering thehorn attheedge BB.Accurate wood-working makes possi- blethe use ofplywood construction which ispreferable toaluminum in weight and ease ofmanufacture. 
 ING AT A SPEED DETERMINED  BY THE MEAN WIND ALOFT  AND HAVE A MEAN DOPPLER FREQUENCY  SIGNIFICANTLY DIFFERENT FROM THAT OF THE SURFACE CLUTTER )F THE -4) FILTER IS TRACKING THE SURFACE CLUTTER  THE SPECTRA OF THE SOURCES WITH A DIFFERENT MEAN DOPPLER FREQUENCY LIE IN THE PASSBAND OF THE -4) FILTER !  
 120. Bramley, E. N., and S. 
 NOISE RATIO  QKJ IN THE FOLLOWING  o  4HE 2#3 IS CERTAINLY A FLUCTUATING QUANTITY VERSUS TIME IT ALSO DEPENDS UPON THE TARGET ASPECT ANGLE (OWEVER  IF  ENOUGH TIME 
 Thisisusuallyimportant onlyatlowaltitudes.It canbereducedbyanattenuator introduced inthetransmission lineatlowaltitudeorbya directional coupleroranisolator. 5.Thedouble-bounce signal. Reflections fromthelandinggearcanalsocauseerrors.. 
 47. pp. 371 --396,  Mar.. 
 46. A. Farina and F. 
 POLARIMETRIC DATA SETS EXIST OF THE TYPE DESCRIBED ABOVE FOR SINGLE POLARIZATIONS &OR MORE COMPLETE DISCUSSIONS OF RADAR POLARIMETRY  CONSULT REFERENCES 5LABY AND %LACHI   3LETTEN AND  -C,AUGHLIN  AND VAN :YL AND +IM 3INCE POLARIMETRIC RADARS USE DEFINED PHASES FOR BOTH TRANSMIT AND RECEIVE  THE  SIGNALS MUST BE DESCRIBED IN THE FORM USED FOR ELLIPTICAL POLARIZATION 4HIS IS ILLUSTRATED IN &IGURE  &)'52%     !NGULAR RESPONSE OF  R  OF DRY SNOW AT DIFFERENT  FREQUENCIES 2APID FALLOFF AT LOWER FREQUENCIES APPARENTLY RESULTS FROM  PENETRATION TO THE SMOOTH GROUND SURFACE AFTER 7 ( 3TILES ET AL . 
 02& RADAR HAS BOTH RANGE AND DOPPLER AMBIGUI 
 , 
 80, Apr. 1, 1965. 42. 
 G. Bath et al.73) ch07.indd   44 12/17/07   2:14:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 NOISE RESPONSE FOR EACH OUTPUT PULSE FROM  THE -4) CANCELER  THE INHERENT LOSS INCURRED IN A SCANNING RADAR WITH -4) PROCESSING  DUE TO THE REDUCTION OF THE EFFECTIVE NUMBER OF INDEPENDENT PULSES INTEGRATED IS NOT  APPARENT 4HIS LOSS IS  D" FOR A  
 The deployed assemblies weighed 135 Ib, and the prime power was 460 W. Seasat-A Synthetic Aperture Radar.18'37 The Seasat-A was a focused SAR consisting of five subsystems: (1) spacecraft radar antenna, (2) spacecraft radar sensor, (3) spacecraft-to-ground data link, (4) ground data recorder and formatter, and (5) ground data processor. The antenna was a microstrip array of eight panels that were fed by a corporate-feed network and operated at 1275 MHz. 
 All these aspects  pose special design problems for GPR, which is described in detail by Daniels.1 This  chapter is a summary of that material and is referenced by courtesy of the IEE. A typical GPR system is shown in Figure 21.1 and consists of a pair of antennas,  one for transmit and one for receive, connected to the transmitter receiver and proces - sor and contained within a sealed enclosure, a battery and control processor, and dis - play unit. The wheels drive a shaft encoder that triggers data acquisition and hence the  display that is synchronised to the movement of the system. 
 The CRT phosphor doubles as an optical and an electronic screen to give  the operator a mixed presentation viewed in the usual manner from the front.  Synthetic-video ~is~la~s.~~~~~~~~ The use of a digital computer, as in an automatic detection  and tracking processor. to extract target information results in a synthetic display in which  target informatiorl is preserited wit11 standard symbols and accompanying alphanumerics. 
 Indicating unit type 162C [ 6]. Figure 4.20. ASV Mk. 
 A small radius of curvature is found with cylindrical (or spherical)   arrays used for 360 ° coverage. Elements are switched to avoid sections of the antenna  where they point away from the desired beam direction. Difficulties may be encoun - tered in matching the radiating elements and in maintaining polarization purity. 
 ALARM RATE &OR EACH PEAK DETECTION  ADJACENT AMPLITUDES WILL BE USED TO OBTAIN AN ACCURATE AMBIGUOUS RANGE ESTIMATE DENOTED  }R I    WHERE THE SUBSCRIPT REFERS TO THE #0) NUMBER !LSO  FROM THE SPECIFIC DOPPLER FILTER CORRESPONDING TO THE PEAK DETECTION DESCRIBED ABOVE  THE PHASE  P I  OF THE RETURN IS  SAVED )N ADDITION  A CORRESPONDING PHASE  PI  OBTAINED FROM AN IDENTICAL SECOND DOP 
 Fortuny, J. Efﬁcient Algorithms for Three-Dimensional Near-Field Synthetic Aperture Radar Imaging. Ph.D. 
 PULSE STAGGERING )MPROVEMENT &ACTOR ,IMITATIONS #AUSED BY 3TAGGERING  7HEN PULSE 
 The radar siteischosen from thestandpoint ofgood coverage, freedom flompermanent echoes, and the like; the criteria entering into thechoice ofsite foracontrol center areusually entirely different. Also, acontrol center should receive supplementary information from other radar installations located elsewhere, even though asingle radar equip- ment may provide theprimary data forcontrol ofoperations. This will enable thecoverage oftheprimary radar tobesupplemented byinforma- tion from neighboring sectors, and will provide coverage ofpossible “blind spots” oftheprimary radar. 
 76–86. 134. G. 
 The ionosonde station is easyto build and has a reasonable cost, so it has been set up worldwide [ 6]. Nevertheless, an inherent issue of the ionosonde is that it can only directly detect the electron density under the peak height. Though many methods have been proposed for modeling the topside proﬁle of ionosphere from the ionosonde measurement, it is still a subject for ongoing investigation [ 7–9]. 
 H. Stewart, D. L. 
 )) "OTH INSTRUMENTS OPERATE AT + U BAND  K(Z    RADIATING  7   MS PULSES AT  (Z 02&  SPLIT EQUALLY BETWEEN THE TWO ANTENNA BEAMS 4HE TRANSMITTER IS A 474!  BASED ON .3#!4 HERITAGE 4HE MODULATED PULSE BANDWIDTH IS  K(Z  WHICH IS MAINTAINED WITHIN AN  K(Z FILTER IN THE RECEIVER   4HE RECEIVED DATA MUST BE COMPENSATED TO OFFSET THE DOPPLER SHIFT  WHICH VARIES  . 
 VI meant that the operator had to exercise continuous control of the gain during search. It was noted in [ 9] that this could be particularly important when searching for schnorkels. As discussed above, detectionof schnorkels was dif ﬁcult and detection ranges could be quite short. 
 (a) fed from one end;  (b) center-fed. 286 INTRODUCTION TO RADAR SYSTEMS  were to arrive in a direction other than broadside, the entire array would not be excited  simultaneously. The combined outputs from the parallel-fed elements will fail to coincide or  overlap, and the received pulse will be smeared. 
 85. Hansen, R. C.: Gain Limitations of Large Antennas, IRE Truns., vol. 
 (4)thenecessity ofkeeping extra- neous capacities toaminimum. Itisforthis reason that theinductance Liseither fixed-tuned orslug-tuned, instead ofbeing used with atuning condenser. Bythesame token, theuseofpoint-to-point wiring and the mounting ofcomponents onthetube sockets areclearly indicated. 
 4.5 OIGITAL SIGNAL PROCESSING  The itltroduction of practical and ecorlomical digital processing to MTI radar allowed a  significant increase in the options open to the signal processing designer. The convenience of  tligirill ~~ioccssi~~g IIIL';~I)S tl~ilt ~l~\tltil>l~ dolay-line cancelers with tailored frequency-response  characteristics can he readily achieved. A digital MTI does not, in principk,do any  hcttcr tl~ar~ :I well-dcsigr~ed analog canceler; but it is Inore dependable, it requires less adjust-  nierits and attet~tiot~, and can do some tasks easier. 
 OFF IN AZIMUTH RESOLUTION IS BALANCED WITH A CORRESPONDING COMPROMISE IN RANGE RESOLUTION  LEAVING EXCESS RANGE BANDWIDTH THAT MAY BE CONVERTED INTO LOOKS 3TARTING FROM A  
 Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Scattering Coefficients from Images.  Radar images produced by real or  synthetic aperture radars can be used for scattering coefficient measurement. 
 SAR antennas with low sidelobes reduce the level of jamming  power received and, in addition, reduce the probability of being intercepted by  ECM stations (in the sidelobe region).169 In relation to low sidelobes, the following  comment is in order. In a conventional radar, the effect of low sidelobes is clear,  but there is a difference in SAR because the beamwidth is much wider than in  other radar applications. In principle, the finer the resolution the smaller the SAR  physical antenna and the wider is its beamwidth. 
 If there were, on the average, only one bird per sqiiare mile, more  than 300 echoes would be displayed on the PPI within a 10-mile radius from the radar. This  represents a significant amount of clutter. It has been said that as few as eight birds per sqiiare  mile can completely blank a PPI screen. 
 OF 
 As discussed in Sec. 2.10, the radar pulse repetition frequency (prf) must be  low enough to avoid range ambiguities and multiple-time-around echoes. An additional con­ straint on the prf occurs in a synthetic aperture radar. 
 The display for a surveillance radar is usually a cathode-ray tube with a PPI (plan position indicator) format. A PPI is an intensity-modulated, maplike presentation that provides the target's location in polar coordinates (range and angle). Older radars presented the video output of the receiver (called raw video) directly to the display, but more modern radars generally display pro- cessed video, that is, after processing by the automatic detector or the automatic detector and tracker (ADT). 
 MIT PULSE TRAIN  BLANK THE RECEIVER DURING TRANSMISSION  AND FORM THE RANGE GATES 2EFERENCE 'ENERATOR  4HE REFERENCE GENERATOR OUTPUTS FIXED FREQUENCY CLOCKS AND  LOCAL OSCILLATORS ,/S  3YNTHESIZER 4HE SYNTHESIZER GENERATES THE TRANSMIT CARRIER FREQUENCY AND THE  FIRST LOCAL OSCILLATOR ,/   FREQUENCY &REQUENCY AGILITY IS PROVIDED TO THE TRANSMIT  AND ,/ SIGNALS #LUTTER /FFSET 'ENERATOR  4HE CLUTTER OFFSET GENERATOR SHIFTS THE TRANSMIT CARRIER  SLIGHTLY  SO THAT ON RECEIVE THE MAIN 
 Radar further permits the measure- ment oftherange oftheobjects it“sees” (this verb will hereafter beused without apologetic quotation marks) with aconvenience and precision entirely unknown inthe past. Itcan also measure the instantaneous speed ofsuch anobject toward oraway from the observing station ina simple and natural way. The superiority ofradar toordinary vision lies, then, inthe greater distances atwhich seeing ispossible with radar, intheability ofradar to work regardless oflight condition and ofobscuration oftheobject being seen, and intheunparalled ease with which target range and itsrate of change can bemeasured. 
 STATION POWER AMPLIFIER BECAUSE OF THE HIGHER GAIN  LINEARITY  AND EFFICIENCY THAT IT DEMONSTRATES COMPARED TO THE SILICON "*4 !LTHOUGH IT IS A &%4  ITS CONSTRUCTION CHARACTERISTICS  PACKAGING  AND DESIGN CHALLENGES ARE VERY SIMILAR TO THE DESIGN CHALLENGES OF THE 3I "*4&)'52%   !  
 Pollock, E. J.: In Loop Integration Control (ILIC), Technical Memorandtim 118, Feb. 1, 1976, Air  Force Special Weapons Center, Kirtland Air Force Base, New Mexico. 
 Therefore, the coherent integration time available at each look is reduced from the total look time by the sum of the space charge time and the transient settling time. The canceler settling time can be elim- inated by 4'precharging" the canceler with the steady-state input value.35 This is done by changing the canceler gains so that all delay lines achieve their steady- state values on the first IPP of data. If no canceler is used, signals can be passed to the filter bank after the space charge is complete, so that the coherent integration time is the total look time minus the space charge time. 
 An intensity-modulated circular display on which  echo signals produced from reflecting objects are shown in plan position with range and azimuth  angle displayed in polar (rho-theta) coordinates, forming a map-like display. An offset, or offcenter,  PPI has the zero position of the time base at a position other than at the center of the display to  provide the equivalent of a larger display for a selected portion of the service area. A delayed PPl is  one in which the initiation of the time base is delayed. 
 Furthermore, the paths are  almost equal, and in most cases, they cannot be resolved by high-range-resolution  techniques. Long time averages of the data do not, in practice, give target elevation;  thus, the multipath angle error has no simple solution and is generally minimized by  using narrow-beam antennas. When the target is at low altitude, the multipath errors are severe, as observed in  the measured data shown in Figure 9.27. 
 R. A. Senior, and P. 
 Many of the I/Q demodulator errors described above are either reduced dramati - cally or eliminated using IF sampling. This, along with the reduction of hardware  required, are the reasons that IF sampling (described in Sections 6.10 and 6.11) is  becoming the dominant approach. 6.10 ANALOG-TO-DIGITAL CONVERTERS The high-speed A/D converter is a key component in receivers of modern radar sys - tems. 
 However, the noise from external sources is then also re- duced by the factor I/1La. The total correction to the temperature values given by Fig. 2.9, to account for both ground-noise contribution and antenna loss, is then given by the following formula: Tatt - TaglTtg) + TagTa = ?*-£ ^ + Tta(l - 1/LJ (2.35«) La where Tar is the temperature given by Fig. 
 The present design ofhigh-voltage, low-average-current rectifying diodes isquite satisfactory. There arenow available diodes ofreasonable dimensions, high inverse rating, and good life, covering most practically useful ratings. Thoriated tungsten cathodes areuniversally employed; these have satisfactory mechanical strength and are economical of filament power. 
 For these wavelengths and grazing angles,  measurements by Crombie indicate that the scattering from the sea surface was the  result of scattering from sea waves of one-half the radar wavelength,5 i.e., “Bragg”  scatter. In the years since these early measurements, there has been considerable  activity in the field of HF radar and HF clutter,52,53 and the results can be sum - marized as follows: For vertical polarization, the major energy of the HF clutter  signal appears in spectral lines displaced to either side of the carrier frequency by  the frequency of sea waves having a wavelength equal to half the HF wavelength l  (in meters). The relative strengths of the plus and minus lines are determined by the  proportion of advancing and receding Bragg-resonant wave components in the clut - ter cell. 
 Tech. , vol. 4, pp. 
 2.8a. These curves were derived from data  given by Marcum. The integration loss is shown in Fig. 
 and com'1inations thereof. 7 The output is designed to filter out the frequency of  interest. usually the uiJTercncc frequency. 
 Insomeofthequoted mathematical results,thelinear-detector lawisassumed, whileinothers,thesquarelawis assumed. Ingeneral, thedifference' between thetwoissmallandthedetector lawinany analysis isusuallychosenformathematical convenience. Whenwespeakofadetector lawwe reallymeanthecombined lawofthe,detector andvideointegrator, ifoneisused.Ifthe. 
 Lin, Y.; Hong, W.; Tan, W.; Wang, Y.; Xiang, M. Airborne circular SAR imaging: Results at P-band.In Proceedings of the 2012 IEEE International Geoscience and Remote Sensing Symposium, Munich, Germany, 22–27 July 2012; pp. 5594–5597. 
 Ifa3-phase rotor isused, themachine becomesa “differential,” which effectively subtracts the two angles in developing itsoutput voltages. Three-phase synchros arewidely used inmechanical repeaters. As resolvers where thevoltage itself istobeused, they have thedisadvantage that they donot deliver rectangular “components.” Ifonly one com- ponent isneeded, however, asinatype Bortype Cdisplay (using the approximation sine=O)they areoften used because oftheir somewhat higher accuracy and their greater availability. 
                                    . 
 LAW DETECTOR  OF THE TARGET RETURN COMPARED TO THAT OF JUST NOISE 4HE ENVE 
 It was installed at the U.S. Kwajalein Missile  Range in 1980 as an adjunct to the TRADEX  L band monostatic radar.40 TRADEX   operated in its normal monostatic mode, acquiring, tracking, and illuminating ballistic  missile reentry vehicles (RVs). Two unmanned, slaved receive stations, located about  40 km from TRADEX , received echoes bistatically scattered off the RV and recorded  bistatic range, doppler, and signature data from RVs. 
 FEED CONFIGURATION TO DISTRIBUTE THE POWER TO EACH ANTENNA ELEMENT OR AN ELECTRONICALLY SCANNED PHASED ARRAY EMPLOYING AT EACH ANTENNA  ELEMENT A SMALL SOLID 
 2.. Jr., and G. H. 
 This isnottooimportant inpractical radar design, forsomany factors areinvolved inthereal problem that we cannot hope for, and donotneed, avery precise answer tosuch questions. We shall most frequently assume, inlater chapters, that the required signal power varies asl/~;. Itmust beobserved, toput the above considerations inproper per- spective, that thebenefits ofintegration arenotconfined tothesmoothing out ofthermal orpurely random noise. 
 TEM DESIGNED TO DESTROY THE THEATER BALLISTIC MISSILE THREATS TO TROOPS  MILITARY ASSETS   AND ALLIED TERRITORIES 4(!!$ CONSISTS OF A HIT 
 That is,kcrefers tothe wavelength inspace. For rectangular guide, asshown from the stub- supported two-wire line, thecutoff wavelength istwice thebroad dimen- sion. Inother words, aewide that istotransmit awave must have a broad dimension greater t~an half afree-space wavelength. 
 17.15] AGROUND-TO-QROUND RELAY SYSTEM 731 Fm.17.21.—Comparative PPI photograph taken eimultaneouely atthetransmitting and atthereceiving etatione.. 732 RADAR RELAY [SEC.17.10 pulses ispossible (with the amplitude-modulated equipment ),these effects aregreatly reduced. Amplitude selection also provides suppres- sion ofweak interference picked uponthe link itself. 
 A. V.: System for Space-Scanning with a Radiated Beam of Wave Signals, U.S. Patent  No. 
      VP VP V! !E!!E2JT 32 JT ;   = ;   = VV P VV P 
 These radars employ  electronic phase scanning in bearing and/or in elevation  (phased -array -antenna).   Elevation Angle   The elevation angle is the angle between the  horiz ontal  plane and the line of sight, measured in the vertical  plane. The Greek letter Epsilon (ε) describes the  elevation angle. 
 predicted at 37 nm. These ﬁgures suggest relative sensitivities of +9.2 dB and +7.9 dB (compared with the rough ﬁgure of merit values of 10.5 dB and 8 dB). The actual values from trials in table 7.1are slightly lower, representing increases in noise-limited sensitivities of +8.6 dB and +5.9 dB, compared to ASV Mk. 
 A.: An Algorithm for Calculation of Range in Multiple PRF Radar, IEEE Trans., vol. AES-12, pp. 287-289, March 1976. 
 CLUTTER RATIO IMPROVEMENT )3#2  4HE RATIO OF THE SIGNAL 
   30!#% 
 inserted, the image is erect and is simultaneously  focused in the range and cross-range dimensions, but it lies at infinity. To bring the image to  some conveniently located plane, a spherical lens is inserted. A vertical slit in an opaque screen  placed in the focal plane of the spherical lens displays all ranges in a particular direction. 
 ABLY BE DETECTED IE  CROSS A DETECTION THRESHOLD  MANY TIMES  EG  IN ADJACENT RANGE CELLS  AZIMUTH BEAMS  AND ELEVATION BEAMS 4HEREFORE  AUTOMATIC DETECTION SYSTEMS HAVE ALGORITHMS FOR MERGING THE INDIVIDUAL DETECTIONS INTO A SINGLE CENTROIDED DETEC 
 The blind speeds of two independent radars operating at the same frequency will be  different if their pulse repetition frequencies are different. Therefore, if one radar were "blind "  to moving targets, it would be unlikely that the other radar would be" blind" also. Instead of  using two separate radars, the same result can be obtained with one radar which time-shares  its pulse repetition frequency between two or more different values (multiple prf's ). 
  D"C  
 SPREAD SCATTERING REFERRED TO AS SPREAD 
 Caduff, R.; Schlunegger, F.; Kos, A.; Wiesmann, A. A review of terrestrial radar interferometry for measuring surface change in the geosciences. Earth Surf. 
  0 ;ONE SIDELOBE   24=]N  AND FOR 0 ;ONE SIDELOBE   24=      0 ;N SIDELOBES   24=     
 The beam - width (in radians) qB of an aperture antenna is given approximately by the wavelength Chapter 17 *  The present chapter draws significantly from Dr. Sullivan’s book, Radar Foundations for Imaging and Advanced  Concepts , Raleigh, NC: SciTech Publishing, 2004. Dr. 
 The reduction inthenumberofelements depends onthesolidangleoverwhichthemainbeamis positioned. Forexample, ifthebeamistobescanned anywhere withinaconedefinedbya. 334 INTRODLJCTION TO RADAR SYSTEMS  half-angle of 45", the number of elements required with triangular spacing is 13.4 percent less  than with square spacing. 
 F WITH THE COMPLEX CONJUGATE  !   OF THAT COMPLEX AMPLITUDE )F A BAND OF POSITIVE FREQUENCIES FROM  F TO F IS OCCUPIED  BY SPECTRAL COMPONENTS  THE CORRESPONDING BAND OF NEGATIVE FREQUENCIES FROM  
 liardin, and J. Munishian: A Time Duplexed Monopulse Receiver, Cot$ Proc. on  Alilitnry Elactrotrics Cotrri. 
 2'0/ IS  CONSIDERED AN %##- TECHNIQUE 7HENEVER 2'0/ IS ACTIVE  TWO HIGH 
 it might be possible to  control the radiation so as to illuminate the surface with less energy than the conventional  fan-beam antenna.  Multiple elevation (stacked) beams, The use of contiguous beams stacked in elevation has been  employed for 30 radar. It is sometimes called a stacked-beam radar. 
 ING SOURCES AT  '(Z IN TWO TREATMENTS OF TALL 
 Aero11aut. Electronics  (Dayton, Ohio), pp. 133-144. 
 ARRAYS IT APPROXIMATELY  FOLLOWS THE UNIFORM TAPERING DASHED LINE  $OTTED LINE PATTERN OF ARRAY OF ELEMENTS AND OF ARRAY OF SUB 
 A Fourier-based image formation algorithm for GNSS-based bistatic forward-looking synthetic aperture radar is presented in [ 16]. Returns form objects with complex motion in an ISAR imaging system are modeled as multicomponent quadratic frequency modulation (QFM) signals. QFM signals’ parameter estimation based on two-dimensional product modiﬁed parameterized chirp rate-quadratic chirp rate distribution is discussed in [ 17]. 
 , Ê " 
 321. Sensors 2019 ,19, 1529 ȱ (a)ȱ (b)ȱ (c)ȱ (d)ȱ Figure 12. Simulated SAR eddy images under different radar look directions. 
 Sd. Rept. CS-9, AZ)-A041316, June 1977. 
 Thus when a particular frequency channel is desired, the  tuner mechanism provides the correct tuner position for each cavity to achieve the desired  klystron frequency response. The klystron differs from other tubes in that the higher the peak  power, the greater can be its bandwidth.48•50  Other properties. The RF conversion efficiency of klystron amplifiers as used for radar might ,  range from 35 to 50 percent. 
 The radar beam inik360° sweep may look over land, over water, orover both land and water. Figure 15.4. 594 EXAMPLES OFRADAR SYSTEM DESIGN [SEC. 
 The horizontal  bright line, known as the ‘trace,’ is constant. The vertical  deflections, showing as spikes of light, indicate radar refiec-  tions from various objects. The rule above the trace 1s  graduated in miles. 
 67. Trunk, G.cV.: Comparison of Two Scanning Radar Detectors: The Moving Window and the Feed-  back Integrator, IEEE Trans., vol. AES-7, pp. 
 FREE OPERATION 7E WILL SEE THAT FOR BANDPASS SIGNALS A SAMPLING RATE HIGHER THAN .YQUIST MAY BE REQUIRED TO AVOID ALIASING IN SOME SITUATIONS 4HE .YQUIST RATE IS OFTEN SAID TO BE TWICE THE SIGNAL BANDWIDTH   BUT THAT REFERS TO A  ONE 
 Bistaticradarcrosssections for various-shaped objectshavebeenreported intheliterature.6o68Twocasesofbistaticradar crosssectionwillbeconsidered. Inonethescattering anglef3(defined inFig.14.12)isexactly equal10IHOO.Inlheolher,fJcanlakeanyvalueexcept1800 • Consider firstthecascwherefJ=1=180°,forwhichthefollowing theorem applies:"Inthe limitofvanishing wavelength thebistaticcrosssectionforthetransmitter directionkand receiver direction ;10isequaltothemonostatic crosssection forthetransmitter-receiver direclionk+frowithk=1=;'0forbodieswhicharesufficiently smooth." Inthepreceding,kis theunitvectordirected fromthetransmitter tothetargetand110istheunitvectordirected fromthereceiver tothetarget.Thetargetisassumed tobelocatedattheoriginofthe coordinate system.Thistheorem permitsbistaticcrosssections tobedetermined frommono­ staticcrosssections provided theconditions underwhichthetheorem isvalidaremet. Itmaybeconcluded fromtheabovetheorem thataslongasf3=1=1800therangeofvalues ofbistaticcrosssectionforaparticular targetwillbecomparable withtherangeofvaluesof monostatic crosssection. 
 The duplexer might consist of  two gas-discharge devices, one known as a TR (transmit-receive) and the other an ATR  (anti-transmit-receive). The TR protects the receiver during transmission and the ATR directs  the echo signal to the receiver during reception. Solid-state ferrite circulators and receiver  protectors with gas-plasma TR devices and/or diode limiters are also employed as duplexers. 
 Thesidelobe levelis30.6dB downforp=2,butthegainrelativetoauniform distribution is56percent. Additional properties ofthisdistribution canbefoundinRef.1,table6.2,andinRef.5,table1. Aperture blocking.9-12Anobstacle infrontofanantennacanaltertheaperture illumination andtheradiated pattern.Thisiscalledaperture blocking orshadowing. 
 The conventional motors may be provided in a dupli- cate drive with a small residual opposing torque to reduce backlash. Amplifier gain and filter characteristics as well as motor torque and inertia determine the velocity and acceleration capability or the ability to follow higher-order motions of the target. It is desired that the antenna beam follow the center of the target as closely as possible, which implies that the servosystem should be capable of moving the an- tenna quickly. 
 Focusing action is obtained -by constraining the waves 10 pass between the  plates in such a manner that the path length can be increased above that in free space. In one  type of cylindrical constrained lens with the E field parallel to the plates, a IO beam couid bt:  scanned over a 100° sector by positioning the line fced.52 The kns was 72 wavelengths in si1e,  had an .flD = 1.5, and operated at a wavelength of 1.25 cm.  Luneburg lens. 
 Figure 7.7 shows 3 examples.  . Radar System Engineering  Chapter 7 – CW and FM -CW Radar  45       € T=Peroid ,  € Δf=Frequency sample ,    € fT(t)=Transmit frequency     € fR(t)=Receiving frequency =fT(t−τ)±fD,    € fB="Beatfrequency "(Mixeroutput )=fT−fR    Figure 7.7  FM CW modulation schemes. 
 OUT IS THE CHANGE OF THE TRANSMITTED PULSE PHASE DURING THE PULSE DURATION WITH RESPECT TO THE PHASE OF THE REFERENCE OSCILLATOR )F THE COHO LOCKED PERFECTLY TO THE END OF THE TRANS 
 CATIONS -ORE GENERAL COVERAGE IS FOUND IN 3HERMAN  AND ,EONOV AND &ORMICHEV !MPLITUDE 
 I looper. and R. S. 
 antenna. The performance ofthe set with 3-cm beacons isespecially good because careful attention was paid totheradar-beacon problem indesign. The major changes involved inswitching from search tobeacon operation are: 1.Change ofpulse length from 0.8to2.2psec. 
 Savill: Practical Experience with Rear Port Displays, Intrrnurionul Conjr-  ence on Displays for Man-Machine Systems, 4-7 April, 1977 IEE (London) Conference Publication no.  150, pp. 17-19. 
 WINDOW DETECTOR 4HE BATCH PROCESSOR  LIKE THE BINARY INTEGRATOR  IS EASILY IMPLEMENTED  IGNORES INTER 
 The larger the ratio of f/D, the better the  radiation pattern. (The diameter D in the parabolic torus is the diameter of the illuminated  area rather than the diameter of the torus itsetr.) The highest sidelobes produced by the  parabolic torus do not lie within the principal planes. The inherent phase errors of  the parabolic-torus surface due to its deviation from a true parabola can cause sidelobes on  the order of 15 dB in intermediate planes.38 These sidelobes usually lie in the 45° plane and are  called eyes, because of their characteristic appearance on a contour plot of the radiation  pattern. 
 In the CARPET 1.0 manual,197 the equations  for calculating the contributions from chaff (volume clutter) in the signal-to-   interference ratio are described on pp. 59 and 60, and the equations for calculating  the contribution from noise jamming (barrage or responsive) are described on p. 61. 
 :v60- 0.a o G40 c (lJ U 0<-W20 Ol--_--L__---L__ ....L-__..L-_--' a20406080100 Holfanglesubtended byparaboloid atfocusFigure7.8Efficiency ofaparaboloid asafunction of lhehalfanglesubtended bytheparaboloid atthefocus. (FromC.Cutler,9 Proc.IRE.). 238 INTRODUCTION TO RADAR SYSTEMS  radiated toward the edge of the reflector should usually be about one-tenth the maximum  intensity. 
 Thereference axisintheRieke diagram usuallycorresponds totheoutputterminals ofthemagnetron ortheoutputflangeof thewaveguide. Theangleinaclockwise direction fromthisreference axisisproportional to thedistance (inwavelengths) ofthestanding-wave-pattern minimum fromthereference point. Anadvantage oftheSmithchartforplottingtheeffectsoftheloadonthemagnetron parameters isthattheshapesofthecurvesarepractically independent oftheposition oftherderence pointusedformeasuring thephaseoftheVSWR. 
 Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar.  SYNTHETIC APERTURE RADAR  17 .136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 Pulse Repetition Frequency (PRF) Requirements for SAR.  For broadside  operation, the apparent angular velocity of the scene rotation is  Ω =V R (17.12) With respect to the radar, the relative velocity of point A (see Figure 17.6) at the  first null of the main beam is  v rV RR DV DA= − = −    = − Ωλ λ 2 2 (17.13)FIGURE 17.5  Slant and ground planes: The slant plane is determined  by the radar line-of-sight and its perpendicular in the ground plane. 
 These latter sets aretheASD, animproved redesign oftheASD called the ASD-1 ortheAN/APS-3, and theASH orAN/APS-4, asetsimilar tothe other two, but representing avery complete redesign with the principal object ofreducing bulk and weight. The 18-in. paraboloid antennas oftheASD and theAN/APS-3 aremounted inanacelle faired into the leading edge ofthe wing ofasingle-engined aircraft. 
 For most soils of interest in GPR, the  magnetic response is weak and need not be considered as a complex quantity, unlike  the permittivity and conductivity. However, in certain soil types, such as those derived  from volcanic rocks or otherwise high in iron content, full consideration of the mag - netic properties is necessary. In the case of lossy dielectric materials, both conduction  and dielectric effects cause absorption of electromagnetic radiation. 
 Johnson. C. M.: Laser Radars. 
 Sparking isaninternal discharge inthe magnetron which arises asa consequence ofthe generation ofbursts ofgas withh the tube. The gasmay beliberated from theanode orfrom thecathode; ineither event thefrequency ofthe phenomenon ismultiplied byanincrease inanode voltage, anode current, orpulse length. Operation ofamagnetron under .conditions which exceed specifications forany ofthese quantities results inavery rapid increase insparking rate. 
 These invari- ably present range. Two such displays onasingle tube are sometimes used toobtain directional information bycomparing signal intensities from two different beam lobes. II.Two-dimensional intensity-modulated displays. 
 Its synthetic aperture is generated by moving the radar on the rail [ 11]. This type of working mode limits its ﬁeld of view. A new mode GBSAR called ArcSAR can solve this problem. 
 While the general ac- curacy of the optics region approximations improves as the scattering obstacle becomes electrically larger, some of them give reason- ably accurate results (within 1 or 2 dB) for ob- jects as small as a wavelength or so. The theory of geometric optics is based on the conservation of energy within a slender fictitious tube called a ray. The direction of propagation is along the tube, and contours of equal phase are perpendicular to it. 
 ENDED WAVEGUIDE IN FRONT OF EACH SLOT  WITH DIMENSIONS THAT MAKE IT BELOW CUTOFF FOR VERTICAL POLARIZATION 3LOT CHARACTERIZATION IS NORMALLY PERFORMED BY MEASUREMENT  RATHER THAN BY  DETAILED ELECTROMAGNETIC ANALYSIS 4HIS ALLOWS ALL CONSTRUCTION DETAILS  INCLUDING THOSE REQUIRED FOR POLARIZATION FILTERING  TO BE INCORPORATED INTO THE SLOT CHARACTERIZATION SUFFICIENT ACCURACY IS DIFFICULT TO ACHIEVE USING NUMERICAL ANALYSIS 0ROVIDED THE CHAR 
 The receiver filters the signal to separate desired echoes from interference in many ways, but some elements of such processing are covered by other chapters because of the depth of treatment required: Chapter 14 describes continuous-wave (CW) and FM-CW radars; the discus- sion here will be confined to receivers for pulse radars, the dominant form. Low- pulse-repetition-frequency (PRF) pulse radars transmit a burst of energy and lis- ten for echoes between transmissions. Their outstanding advantage is that neither leakage from the transmitter nor the very strong echoes from close-range clutter occur at the same instant as reception of weak echoes from long-range targets. 
 2015DFA10270. Conﬂicts of Interest: The authors declare no conﬂict of interest. References 1. 
 512] SUMMARY 157 inany way unusual has been found tohave ground clutter 75dbabove noise. Under these conditions, the MTI system would not beexpected towork; the above-described system does work. 6.12. 
 ING VARIOUS FORMS OF HIGH 
 On  receive, multiple beams are simultaneously formed in a cluster that covers the volume  illuminated by the transmit beam. Each receive beam has the full gain and beamwidth  of a single beam array with the same aperture dimensions. In the cluster of receive  beams, each of the receive beams may be offset in various directions from the center of  the spoiled transmit beam. 
 The progression of f d is demonstrated in  Figure 9.5.  Tow points P and P’, which have the same distance R0 from the Radar, distinguish  themselves in azimuth are the route D.  This route of the Radar is flown in the following time:   € Δt=D v⋅1 sinθ0 (10.15)  Substituted into Equation (9.14) the following Doppler frequencies for P and P’ result:   € fd(P)=2v λcosθ0(t=0)         (10.16)  € fd(P')=2v λcosθ0−v2D λR0sinθ0 (t=Δt)          (10.17)  The Doppler frequencies between P and P’ amount to:   € Δfd=2vD λR0sinθ0 (10.18)  The maximum sampling period T in order to separate these 2 targets with a distance D is ca l- culated by:   € T=1 Δfd (10.19)  In time T the Radar moves along the route, which corresponds to the synthetic aperture L:   € L=vT=R0λ 2Dsinθ0 (10.20) . 
 W. J. Humphreys, Physics of the Air , New York: McGraw-Hill Book Company, 1940, p. 
 INTERFERENCE ENERGY RATIO WITHIN A RADAR RESOLUTION CELL WHEN THE ANTENNA APERTURE AND THE RADAR DATA RATE ARE HELD CONSTANT 4HE INCREASED FREQUENCY INCREASES BOTH THE ANTENNA GAIN AND THE NUMBER OF RADAR RESOLUTION CELLS THAT MUST BE SEARCHED BY EQUIVALENT AMOUNTS THE NET EFFECT IS THAT THE TARGET RETURN POWER IS INCREASED BY THE SAME AMOUNT BY WHICH THE TARGET DWELL TIME IS DECREASED  THEREBY  HOLDING THE TARGET 
 In Proceedings of the Tenth International Workshop on Frontiers in Handwriting Recognition, La Baule, France, 23–26 October 2006. 27. Aghdam, H.H.; Heravi, E.J. 
 HORN FEED IS A PRACTICAL CHOICE BETWEEN COM 
 Some beacons have been used foridentifying ships, others forenabling aircraft tohome ontheir carriers oron convoys.. SEC. 8.1] TYPES OF RADAR-BEACON SYSTEMS249 3.Airborne beacons. 
 7.2 supply and maintain the equipment required bymechanization. The advantage ofmaking this substitution istwo-fold: the latter skills can beapplied under favorable conditions, while operator skill isrequired in the field onthe occasion ofeach crisis; further, there areusually many more operators ofagiven equipment than there aredesigners, production engineers, and maintenance men, combined. The total skill required is thus more economically used under more favorable conditions ifmech- anization isemployed. 
 B.: A Review of Circular Polarization as a Means of Precipitation Clutter Suppression and  Exumples, Proc. Natl. Electronics Con& (Chicago), vol. 
 The original image from TerraSAR-X was used as RCS of the extended target to simulate MPS SAR data with the imaging geometry in Figure 1and the simulation parameters listed in Table 1. It should be noted that the height of the targets in this real SAR scene is less than the elevation resolution 55 m. The focused 2D images were then processed by the proposed method to suppress the azimuth sidelobes. 
 %3, 3!4#/- 7ORKBENCH  IS A -ICROSOFT 7INDOWSnBASED MODULAR  SOFTWARE PACKAGE FOR 0# PLATFORMS RUNNING 7INDOWS 80 )T CONTAINS A VARIETY OF MODULES OR SO 
 Hock(requenzted1. an der E. T.H. 
 Goode: Adaptive Antenna Systems, Proc. IEEE.  vol. 
 The signal-to-clutter ratio, after cancellation or doppler filtering, that  provides stated probabilities of detection and false alarm.  Cltrtter attenuation. The ratio of clutter power at the canceler input to the clutter residue at the  output, normalized to the attenuation of a single pulse passing through the unprocessed  channel of the canceler. 
 The signal-  to-noise per pulse will always be less than that of an ideal predetection integrator for reasonable  values of P,. It should also be noted that the data in Figs. 2.23 and 2.24 are essentially  independelit of the false-alarm number, at least over the range of lo6 to 10". 
 110. Thorn, H.: Distribution of Extreme Winds in the United States, ASCE Trans., vol. 126, pt. 
 Pub. 216, London, October 1982, pp. 444–447. 
 The skew is range- and angle-dependent. The range-dependent skewing effect is not present in an airborne monostatic radar. Clutter spread in a particu- lar sidelobe range cell is centered on the doppler skew present in the range cell. 
 BAND INTERFER 
 13.) I-(I- Pfaf = 0.5 (2.22«) For the usual large values of n' that are of interest, a highly accurate approximate solution of this equation for Pfa is ^.!e^.o^l C.22H Fluctuating Target Cross Section. In general, the effect of fluctuation is to require higher signal-to-noise ratios for high probability of detection and lower values for low probability of detection than those required with nonfluctuating signals. Swerling has considered four cases, which differ in the assumed rate of fluctuation and the assumed statistical distribution of the cross section. 
  
 Scudder, R. M., and W. H. 
 A limiter may be necessary to ensure  this. An N-bit converter divides the output of the phase detector into 2N 1 discrete intervals.  According to Shrader,8 the quantization noise introduced by the discrete nature of the A/D  converter causes, on the average, a limit to the improvement factor which is  Io.N = 20 log [(2N -l )j0.75] (dB) (4.12)  This is approximately equal to 6 dB per bit since each bit represents a factor of two in  amplitude resolution.22 When a fixed signal of maximum level is present, a possible error of  one quantization interval is possible. 
 For large sensor biases and non-fading  targets, track-to-track is preferred. ( after W.Bath77 © IEE 2002 ) ch07.indd   48 12/17/07   2:14:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 J.: Array Beam-Forming Networks, MIT Lincoln Luhoratol.y Trchttical Noir 1965- 12.  13 April 1965.  162. 
 The leakage signal entering the receiver via coupling between transmitter and receiver  antennas. This can limit the ultimate receiver sensitivity, especially at high altitudes.  4. 
 The accuracy along either the time axis or the -  frequency axis can be made as good as desired. However, the accuracy along the ellipse major  axis is relatively poor. This is a consequence of the fact that both the time delay (range) and the  frequency (doppler) are both determined by measuring a frequency shift. 
 IT-6, pp. 269-308, April 1960. 48. 
 Sidelobes. The lobe structure of the antenna radiation pattern outside the major-lobe (main-beam) region usually consists of a large number of minor lobes, of which those adjacent to the main beam are sidelobes. However, it is common usage to refer to all minor lobes as sidelobes, in which case the adjacent lobes are called first sidelobes. 
 A modula - tor basically consists of an energy storage device, which may be a capacitance or a  pulse forming network, and a switch for triggering the dc pulse. The switch in the  past might have been a vacuum tube, thyratron, ignitron, silicon-controlled rectifier  (SCR), reverse-switching rectifier, spark gap, or magnetic. However, the solid-state  switch seems to be the switching mechanism that should be considered initially when  designing a transmitter modulator. 
 Aparticularly successful version ofthe series-gap switch isthe Bell RTe1ephoneLaboratories’ 1B42, which substitutes amercury-sat- \urated iron “sponge” forthesolid aluminum cathode ofthe1B22. By \Voltage dwider / R FIG. 10.39.—Series gaps.(r ‘tTrigger input FIG. 
 All the dipoles shown inFigs. 9.19 and 9.22 are horizontal and therefore radiate energy polarized horizontally; butalternate dipoles are reversed end-for-end inassembling the array. The spacing between the centers ofadjacent dipoles is one-half the guide wavelength when the guide is1.200 in.wide. 
 Feedback  or infinite impulse response (IIR) filters would not be used with a step-scan system  because of the long transient settling time of the filters. The limitation on I due to internal-clutter fluctuations can be determined by sub - stituting the appropriate value of sf into Eqs. 2.23 to 2.25. 
 Another important application of radar designed for the detection of weather  echoes is in airborne weather-avoidance radars, whose function is to indicate to the aircraft  pilot the dangerous storm areas to be avoided.  498INTRODUCTION TORADAR SYSTEMS seenbyafixed-site radaristoerectan~Iectromagnetically opaquefencearoundtheradar(or simplybetween theradarandthecluttersource)topreventtheradarfromviewingtheclutter directly.Thetwo-way isolation provided byatypicalfencewithastraightedgemightbeabout 40dB,wheretheisolation isgivenbytheratioofthecluttersignalintheabsenceofafenceto thatinthepresence ofthefence.Theisolation islimitedbythediffraction oftheelectromag­ neticenergybehindthefence.Greater isolation thanthatprovided byastraight-edged fence canbehadbyincorporating twocontinuous slotsnearto,andparallelwith,theupperedgeof thefencetocancelaportionoftheenergydiffracted bythefence.Thedouble-slot fencecan increase thetwo-way isolation by20dBormore.62 Afencecansuppress theclutterseenbytheradar,butitproduces othereffectsnotalways desirable. Forexample, itwilllimittheaccuracy ofelevation-angle measurement because of theblockage ofthefenceandtheerrorcausedbytheenergydiffracted bythefence.Energy diffracted bythefencealsointerferes withthedirectpathfromtheradartocadsemuhipath lobingoftheradiation patternintheangular regionjustabovethefence.Radarenergy hackscattered fromthefencecansometimes belargeenoughtodamage thereceiverfront-end. 
 OF 
 Winter. 1965.  1 17. 
 Farnett and  George H. Stevens for the “Pulse Compression Radar” chapter in the second edition of the Radar Handbook   (1990), edited by Merrill I. Skolnik. 
 Sensors 2019 ,19, 2921 The exponential term of Sc(θ,tr) represents the range migration, which must be compensated during the process of focusing. Therefore, the matched ﬁlter is used to compensate for the range migration of Sc(θ,tr). The ideal matched ﬁlter is expressed as follows: H(θ,tr)=exp⎭braceleftBigg j4πfc c·Rp⎭bracerightBigg (9) However, the actual matched ﬁlter used to compensate for the range migration of target P is diﬀerent from the ideal matched ﬁlter because target P and P 0have diﬀerent range migrations. 
 Kramer, “Recent developments in airborne MTI radars,” Hughes Aircraft  Report, presented at IEEE Wescon 1978. 55. D. 
 OPED  TESTED  AND IN SOME CASES  DEPLOYED FOR MILITARY  COMMERCIAL  AND SCIENTIFIC APPLICATIONS 4YPICAL MILITARY APPLICATIONS INCLUDE AIR AND SPACE SURVEILLANCE AND RANGE INSTRUMENTATION #OMMERCIAL APPLICATIONS INCLUDE WIND FIELD MEASUREMENTS AND TRAF 
 Once this possibility is raised, it is possible to find examples of data that appear to track such a curve while at the same time yielding a power law by linear regression, as illustrated in the tower data shown in Fig. 13.8.31 This behavior is not uncommon. WlNDSPEED (m/s) FIG. 
 ................................ .......................  2  HISTORICAL OVERVIEW  ................................ 
 HAND PIC 
 Eom and A. K. Fung149) ch16.indd   44 12/19/07   4:56:12 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
  
 Military 3D radars and height finding radars are also found at this frequency because of the narrower elevation beamwidths that can be obtained at the higher frequencies. Long-range airborne air surveillance pulse doppler radars, such as AWACS (Airborne Warning and Control System) also operate in this band. Generally, frequencies lower than S band are well suited for air surveillance (detection and low-data-rate tracking of many aircraft within a large volume). 
 COMPRESS %XTENDED CLUTTER TENDS TO BE NOISE LIKE AND WILL NOT PULSE 
 17. pp. 5 1-56, Apr. 
 By operating at a number of different frequencies, the cross section will vary and  can be small or large; but a successful detection becomes more likely than if only a  single frequency were used. This is one reason that almost all air-traffic control radars  operate with two frequencies spaced wide enough apart in frequency to insure that  target echoes are decorrelated and, therefore, increase the likelihood of detection. ch01.indd   9 11/30/07   4:33:41 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Chandrasekar, Polarimetric Doppler Weather Radar: Principles and  Applications , Cambridge, UK: Cambridge Univ. Press, 2001. 25. 
 A similar cut by a vertical plane or (o) FIG. 6.1 Typical pencil-beam pattern, (a) Three-dimensional cartesian plot of complete pattern. ELEVATION (DEGREES) (b) AZIMUTH ANGLE (C) FIG. 
 LAW  UNDER THE ASSUMPTION OF EQUAL SIGNAL AMPLITUDES 7HEREAS FOR A PHASED ARRAY  THE EQUAL AMPLITUDE ASSUMPTION IS VALID FOR A ROTATING RADAR  THE RETURNED SIGNAL AMPLITUDE IS MODULATED BY THE ANTENNA PATTERN AS THE BEAM SWEEPS OVER #HAPTER  Ç°£. Ç°Ó  2!$!2 (!.$"//+  THE TARGET -ANY AUTHORS HAVE INVESTIGATED VARIOUS DETECTORS  COMPARING DETECTION PER 
 Target cross section. The radar cross section oh of a target illuminated by a bistatic radar is a  measure of the energy scattered in the direction of the receiver. Ellstatic radar cross sections for  various-sllaped objects have been reported in the literat~re.~' 68 TWO cases of bistatic radar  cross section will be considered. 
 I.26  Index terms  Links   MTI radar:  (Continued)   from a moving platform ( see AMTI radar)  optimum clutter filters 15.16  phase-sensitive detector in 3.33  and PRF stagger 15.16  and pulse compression 15.50 15.55  and pulse doppler radar 17.2  quantization noise in 15.53  and response to moving targets 15.7  scanning modulation in 15.14  stability requirements in 15.45  staggered PRF in 15.34  STC in       15.69  subclutter visibility in 15.13  time-varying weights in 15.40  and transmitter stability 4.25 4.30  visibility factor in 15.14  Multifunction radar 7.1  Multimode guidance for missiles 19.21  Multipath:  in height finding 20.32  in missile guidance 19.30  in tracking radar 18.46 18.54  Multiple-PRF ranging 17.20  Multiplier detector 3.36  Multistatic radar 25.1  N  NAVSPASUR    5.3 5.8 5.28   5.29  Near-field ranges 6.56  Netted radar 8.43  This page has been reformatted by Knovel to provide easier navigation. I.27  Index terms  Links   NEXRAD       23.1 23.13 23.18  Neyman-Pearson criterion 8.2  Nodding-antenna height finding 20.3  Noise:  anthropogenic 24.13  in IF limiter 3.30  and interference 24.12  measurement of:  in CW radar 14.11  in pulsed transmitters 14.14  due to target 18.34  and tracking accuracy 18.50  Noise bandwidth 2.14  Noise degeneration in transmitters 4.30  Noise figure 1.7  Noise jamming 9.23  Noise-modulated CW radar 14.28  Noise temperature 2.26 3.11  Nomenclature for radar 1.18 17.1  Noncoherent integration 2.25  Nonlinear-FM pulse compression 10.4  Nonparametric detectors 8.19  North, D. O. 
 TheTaylorpattcrnisspccified bytwoparameters: thedesignsidelobe leveland",which definestheboundary bctween uniform sidelobes anddecreasing sidelobes. TheintegerIt cannotbetoosmall.Taylorstatesthat"mustbeatleast3foradesign-sidelobe ratioof25dB andatleast6foradesign-sidelobe ratioof40dB.Thelarger"is,thesharper willbethebeam. However. 
 Section 12.5 describes reflector analysis  and synthesis methods and associated design software packages. Finally, Section 12.6  briefly reviews mechanical design issues and considerations. 12.2 BASIC PRINCIPLES AND PARAMETERS Fundamentally, reflectors are antennas that work on optical principles, on receive,  focusing energy to a focal point as a lens does for light. 
 Ackroyd, M. H., and F. Ghani: Optimum Mismatch Filters for Sidelobe Suppression, IEEE Trans.,  vol. 
 In 1963 Varian assembled a hybrid tube consisting of klystron cavities in all but the output section, while a cloverleaf traveling-wave circuit was used for the output section. The purpose was to produce a more efficient version of the VA-125 broadband S-band TWT, based on the more effective beam- bunching action of the cavities. The result was not only slightly higher efficiency but also a significant improvement in bandwidth as a result of the flexibility in tuning of the cavities combined with the broad power-bandwidth capability of the TWT output section. 
  &)'52%     0ROBABILITY DISTRIBUTION OF RADAR POINTING WHEN TRACKING  TWO TARGETS WHERE THE LEFT TARGET IS APPROXIMATELY  D" LARGER THAN THE  RIGHT TARGET  4HREE DIFFERENT ANGULAR SEPARATIONS OF THE TARGETS ARE  A    ANTENNA BEAMWIDTH  B   ANTENNA BEAMWIDTH  AND C   ANTENNA BEAMWIDTH. 
 325-332, London, 1973. 21. Farrell, J., and R. 
 but from <J, = <Po to ¢ = <Pm, the antenna gain varies as csc2 ¢. Ideally, the upper limit  <Pm should he 90°. but it is always less than this with a single antenna because of practical  difficulties. 
 The array is shown as a receiving antenna for convenience, but because of the  reciprocity principle, the results obtained apply equally well to a transmitting antenna. The  outputs of all the elements are summed via lines of equal length to give a sum output voltage  E,. Element 1 will be taken as the reference signal with zero phase. 
 IEE, vol. 1 1 I, pp. 275-283, February, 1964. 
 QUENCY F 2 IS FREQUENCY SHIFTED OR MODULATED BY THE ,/ SIGNAL AT FREQUENCY  F, "ALANCED  MIXERS ARE USED TO MINIMIZE CONVERSION LOSS AND UNWANTED SPURIOUS RESPONSES )N ACTIVE MIXERS  MODULATION IS PERFORMED USING TRANSISTORS  AND IN PASSIVE MIXERS  THE MODULATION IS PERFORMED USING 3CHOTTKY 
 Zimmerman: "Electronic Circuits, Signals and Systems," John Wiley & Sons, New York, 1960, p. 237. 48. 
 The advantage of these schemes resides in the decomposition of the  complex processing for adaptive cancellation of the NLI into a network of simple  processing elements that can be conveniently mapped onto a parallel processing archi - tecture based either on Commercial off the Shelf (COTS) technology or custom Very  Large Scale Integration (VLSI) devices. In the literature76–80 it has been shown that  a wide spectrum of technologies can be used like Field Programmable Gate Arrays  (FPGA), Coordinate Rotation Digital Computer (CORDIC) implemented with VLSI  and optical computers. Pioneering work on the use of CORDIC for adaptive null - ing dates back to C. 
 SIGHT ,/3  4HE  BISTATIC ANGLE   A   P 4  P2  IS THE ANGLE BETWEEN THE TRANSMITTER  AND RECEIVER WITH THE VERTEX AT THE TARGET )T IS ALSO CALLED THE  CUT ANGLE OR THE  SCATTERING  ANGLE )T IS CONVENIENT TO USE  A IN CALCULATIONS OF TARGET 
 to the gain as it is in a fully illuminated antenna.  However, the cost of the fixed reflector of the parabolic torus is relatively cheap compared with  antennas which must be mechanically scanned. Nonutilization of the entire aperture is  probably not too important a consideration when overall cost and feasibility are taken into  account. 
  
 of the pulse repetition interval, and frequency or phase coding of the individual pulses.35 10.8 WEIGHTINGANDEQUALIZATION The process of shaping the compressed-pulse waveform by adjustment of the am- plitude of the frequency spectrum is known as frequency weighting. The process of shaping the doppler response by control of the waveform envelope shape is called time weighting. The primary objective of weighting in either domain is to reduce sidelobes in the other domain. 
 Propagation over aReflecting Surface. -If the transmission path lies near areflecting surface itmay bepossible forenergy toreach the target, and hence also forscattered energy toreturn tothe radar antenna, byway ofthesurface aswell asdirectly. The result ofcombin- ingthe direct and the reflected wave atthe target will depend onthe relative intensity and phase ofthe reflected wave, which inturn will depend notonly onthedifference inthelength ofthetwo paths but upon changes ofphase orintensity intreduced inthe process ofreflection. 
 direction the antenna must be moved in order to align the switching axis with the direction of  the target. When the voltages in the two switched positions are equal, the target is on axis and.  its position may be determined from the axis direction. 
 Figure 11.22 shows aschematic view ofatypical tube. The resonant circuit isa reentrant, doughnut-like cavity with grids across thecentral portion. Anelectron gun with aproper focus- ing electrode directs astream of electrons through thegrids. 
 WIDTH IN RADIANS   P " OF AN APERTURE ANTENNA IS GIVEN APPROXIMATELY BY THE WAVELENGTH #HAPTER     4HE PRESENT CHAPTER DRAWS SIGNIFICANTLY FROM $R 3ULLIVANS BOOK   2ADAR &OUNDATIONS FOR )MAGING AND !DVANCED  #ONCEPTS  2ALEIGH  .# 3CI4ECH 0UBLISHING   $R 3ULLIVAN IS GRATEFUL TO 3CI4ECH FOR PERMISSION TO QUOTE  CONSIDERABLE MATERIAL FROM THE CHAPTERS ON 3!2 (E IS ALSO GRATEFUL TO -R -ICHAEL 4ULEY )NSTITUTE FOR $EFENSE  !NALYSES  FOR REVIEWING THE MANUSCRIPT PRIOR TO PUBLICATION AND SUGGESTING MANY IMPROVEMENTS o  )N THE FIRST TWO EDITIONS OF THIS (ANDBOOK  THE CHAPTER ON 3!2 WAS WRITTEN BY $R ,OUIS * #UTRONA  WHO IS NOW  DECEASED )N   $R 3ULLIVAN HAD THE PRIVILEGE OF WORKING WITH $R #UTRONA AT THE %NVIRONMENTAL 2ESEARCH )NSTITUTE OF -ICHIGAN  !NN !RBOR NOW 'ENERAL $YNAMICS  9PSILANTI   AND IS GRATEFUL FOR HAVING LEARNED MUCH FROM HIM CONCERNING 3!2. 
 3.4. Super-Resolution Imaging Algorithm Based on KA-DBS So far, the implementation of the proposed KA-DBS super-resolution imaging approach for WAS radar has been described. Figure 5below shows the whole imaging procedure. 
 Areduction intemperature sensitivity can beobtained withacomposite magnetic circuit3o.31inwhichthemicrowave ferrimagnetic material isinternal tothewaveguide, butatemperature-insensitive, magnetic-flux-limiting ferrimagnetic material isexternal tothewaveguide. Thelatterlimitsandmaintains themag­ neticflux,andhencethephaseshift,atanalmostconstant leveloverthestabilization range.. 1111. 
 ISAR Imaging of Multiple Targets Based on Particle Swarm Optimization and Hough Transform. J. Electromagn. 
 The  technique consists of sending skyward a train of very  short radio pulses, a minute fraction of a second in  length, and measuring the time taken for each reflected  pulse to return to earth.  In Britain Dr E. V. 
 However, in principle, all antennas are dispersive to some extent but nondispersive  antennas do not need correction in the signal processing, which reduces the overall  complexity of the radar processing. The very short range operation of many GPR  systems enables operation of antennas in a way that does not conform to traditional  analytic models of antenna gain and aperture. Horn antennas have found most use with FMCW ultrawideband radars where the  generally higher frequency of operation and relaxation of the requirement for linear  phase response permit the consideration of this class of antenna. 
 STATE MODULE IS ASSOCIATED WITH EACH RADIATING ELEMENT IMPROVEMENTS IN TERMS OF APERTURE CONTROL  RELIABILITY  AND EFFI 
 This wave- form usually consists ofalinearly increasing voltage wave which begins attheinitiation ofthesweep and returns totheinitial condition atitsend (Waveform c,Fig. 12.1). This involves aswitching action which, as indicated inFig. 
 TecSAR.  The first space-based SAR from Israel, TecSAR is a featured element  of their national satellite technology development program.25 Launched by India,  TecSAR’s nominal strip-map mode is multi-look 3-m resolution at X band. Major  additional objectives include large area coverage as well as high resolution, which  imply ScanSAR and SpotSAR modes, respectively. 
 92. T. M. 
 PROCESSING SUITE 4HERE  IS SUBSTANTIAL DATA TRAFFIC BETWEEN THE CORE PROCESSING AND THE SENSORS TO PROVIDE POINT 
 .~;l:,"t.. I~IIOI~AC;AI.ION 01: KADAK WAVES 467  3. Shcrwood. 
 The waveform is a single pulse of sine wave  whose frequency is decreased linearly fromf0 + llf /2 tof0 -fl.//2 over the duration of the pulse  T. where Jo is the carrier frequency and llf ~ B is the frequency excursion.  The ambiguity diagram is elliptical, as for the single pulse of unmodulated sine wave. 
 PING COVERAGE COULD PROVIDE SOME %##- BENEFITS )N THE NETTED MONOSTATIC CASE  THE RADARS HAVE DIFFERENT FREQUENCIES FOR INTERFERENCE REDUCTION PURPOSES CONSEQUENTLY  THE %#- HAS TO CONSIDER JAMMING ALL RADARS IN THE OVERLAPPING ZONE  THUS REDUCING ITS EFFICACY 4HIS IS THE KIND OF FREQUENCY DIVERSITY DISCUSSED IN 3ECTION  &INALLY  IT IS WORTH NOTING THAT FRIENDLY %3- CAN SUPPORT %##- ACTION BY WARN 
 AMPLITUDE APPROXIMATION  OR UNDER THE ASSUMPTIONS OF PHYSICAL OPTICS  SURFACE CURVATURES MUCH GREATER THAN THE RADAR WAVELENGTH n. 
 Lab. Rept. 8579, May 1982. 
 Both the spiral scan  and the Palmer scan suffer from the disadvantage that all parts of the scan volume do not  receive the same energy unless the scanning speed is varied during the scan cycle. As a  consequence, the number of hits returned from a target when searching with a constant  scanning rate depends upon the position of the target within the search area.  The raster, or TV, scan, unlike the Palmer or the spiral scan, paints the search area in a  i~niforrn manner. 
 ERAL 
 There is, therefore, a deﬁnite radar horizon. DIFFRACTION Diffraction is the bending of a wave as it passes an obstruction. Because of diffraction there is some illumination of the region behind an obstructionor target by the radar beam. 
 M. Hofstetter, M. Labitt, P. 
 The basic difference between the two is that the  coordinate system moves with the radar in the doppler description, while in the synthetic-  aperture model the coordinate system is fixed to the ground.g  Consider the geometry of Fig. 14.1 in which an aircraft with a sidelooking SAR travels at  a velocity v. (The effect of the elevation angle is neglected in this simple analysis but must be  included in more precise considerations.) When a point scatterer just enters the forward edge  of the beam, it has a doppler frequency 2(u/A) cos (QB/2). 
 VIII. CENTIMETRIC TECHNIQUE  ROM THE EARLIEST DAYS OF RADAR SIR ROBERT  F watson. Watt had realized that greater accuracy,  and in particular the capacity to discriminate between  natural echoes and those from the target, was required. 
 WAVE POWER SOURCES 4HUS  AVAILABILITY OF HIGH POWER IS NOT A LIMITATION AS IT ONCE WAS ,ASER 2ADAR ,ASERS CAN PRODUCE USABLE POWER AT OPTICAL FREQUENCIES AND IN THE  INFRARED REGION OF THE SPECTRUM 4HEY CAN UTILIZE WIDE BANDWIDTH VERY SHORT PULSES  AND CAN HAVE VERY NARROW BEAMWIDTHS !NTENNA APERTURES  HOWEVER  ARE MUCH SMALLER  THAN AT MICROWAVES !TTENUATION IN THE ATMOSPHERE AND RAIN IS VERY HIGH  AND PER 
 (ANSEN  AND ( 2 7ARD  h4RANSMITTER NOISE COMPENSATION! SIGNAL  PROCESSING TECHNIQUE FOR IMPROVING CLUTTER SUPPRESSION v  0ROC  )%%% #ONFERENCE ON 2ADAR    n !PRIL   PP n  4 % 6INGST  $ 2 #ARTER  * ! %SHLEMAN  AND * - 0AWLIKOWSKI  h(IGH 
 Rev., vol. 16, pp. 69–75, 1957. 
 Intheregion where thelineisshown dotted, nocalculations have been ruade. 3.4. Approximations forLarge Metal Targets. 
 In contrast to the design of a corporate-combined output, where significant losses can accrue in the combining circuitry, the solid-state phased array system uses individual transceiver modules to feed antenna elements on an array face. Con- sequently, the phase shifting can be done at a low power level, where dissipated power levels in the phase shifters can be much smaller. The transceiver module, regardless of complexity, has four fundamental functions: (1) to provide gain and power output in the transmit mode, (2) to provide gain and low-noise figure in the receive mode, (3) to switch between transmit and receive states, and (4) to provide phase shift for beam steering in the transmit and receive states. 
 pp. 4 IA  to 4 I I. Sept. 
 The average residue will then beconsiderably less than 6per cent. The corresponding value ofA@is0.06 radian or~ cycle. On substituting this value inEq. 
 FREQUENCY ESTIMATION WITH  DOPPLER METEOROLOGICAL RADARS 4HE ESTIMATES ARE UNBIASED IN THE PRESENCE OF NOISE  WHEN THE DOPPLER SPECTRUM IS SYMMETRICAL )TS GREATEST APPEAL  HOWEVER  IS DUE TO ITS COMPUTATIONAL SIMPLICITY &OR A PULSED RADAR  WITH A PULSE REPETITION PERIOD  4  24  IS  OBTAINED FROM ADJACENT PAIRS OF PULSES USING THE SIMPLE EXPRESSION    24.SSKK K.  
 FERING AMPLITUDES  OFTEN SO GREAT THAT THE DYNAMIC RANGE OF A FIXED 
 The index of refraction r, or the dielectric constant £ varies with the radial distance in a  Lune burg lens of radius r0, according to the relationship  ~ -,;" -[2 -(;J] 1/2 (7.22)  The i;idex of refraction is a maximum at the center, where it equals fi, and decreases to a  value of l on the periphery.  Practical three-dimensional Luneburg lenses have been constructed of a large number of  spherical shells, each of constant index of refraction. Discrete changes in index of refraction  approximate a continuous variation. 
 Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  122     is the CFAR threshold. The following table results for the individual CFAR algorithms with  the CFAR -parameter settings a pplied in Figures 12.8 -12.13.   CFAR Type Quality q q in % CASH 6859 100 MAMIS 6117 89,2 CAOS 6016 87,7 OS 5187 75,6 CAGO 4002 58,3 CA 1998 29,1 Quality  q CFAR Threshold Methods02000400060008000 CASH MAMIS CAOS OS CAGO CA    Figure 12.14  CFAR Threshold quality. 
 Ransone, D. Randall, C Purves, and P. Watkins: Propagation Through an  Flcvated Ouct: Tradewinds Ill, IEEE Trans., vol. 
 The spiky nature of sea echo indicates that the breaking of water waves  plays an important role in producing backscatter. 119  ln addition to changes in clutter characteristics with narrow pulse widths, changes are  also noted with narrow beamwidths. It has been reported 11 that at X hand, small ships stand  out much better with a 2° horizontal beamwidth antenna than when illuminated by a 0.85°  beamwidth antenna. 
 8.12. If B,( 1 ). for example, were the remanent magnetization needed  to produce a phase change of 180° relative to the rem anent magnetization -B,. 
 If the output noise power of the receiver amounts to N A and if the total gain is G, then we have  the following:  GkTBN GNNNFA TA ⋅=⋅=  (6.2) . Radar System Engineering  Chapter 6 – Radar Receiver Noise and Target Detection  29         Figure 6.1  Noise measurement (dB) of various recei ver input stages   The gain is able to be expressed as a quotient of the signal power at the output P A and input P E  of the receiver.   € G=PA PE=PAmin PEmin (6.3)  The minimum receiver input power is calculated with equation (6.4):   € PRmin=NF⋅kTBPA NA=NF⋅kTBN(S/N)=NF⋅NT(S/N) (6.4)  S/N is the required Signal -to-Noise ratio for further analysis. 
 Barnum, “Ship detection with high resolution HF skywave radar,” ibid., pp. 196–210,  April 1986.  7. 
 vol. AES-8. pp. 
 REGION IONIZATION SHOWS MARKED DAY 
 The net main-beam clutter-to-noise power in a single range  gate in the receiver can be approximated from Eq. 4.2 by substituting the range gate’s  intersected area (ct a 2 cos( ) Rqaz) within the main beam on the ground for dA and sum - ming over all ambiguities of that range gate that are within the main beam.33  C NP c L kT BG G RC s nT R=av azλ θ τ πσ α2 30 32 4( / ) ( ) cos( )∑ ∑  (4.3) The summation limits are the lower and upper edges in the elevation dimension of the  smaller of the transmit and receive beams where  qaz = azimuth half-power beamwidth, radians  t = compressed pulse width  a = grazing angle at clutter patch The remaining terms are as defined following Eq. 4.2. 
 30. Ashmead, J., and A. B. 
 Targets that are seen at long range and at a  particular tieight with a cosecant-squared antenna, will be missed at shorter ranges when STC  is used. To incorporate both beam shaping and STC, the pattern must have higher gain at  higher-elevation angles than would a cosecant-squared pattern. Figure 7.27~ illustrates the  antenna elevation pattern for an air-search radar which is desired to compensate for STC and  yet provide a signal independent of range, as does the cosecant-squared pattern." Figure 7.27b  sliows the coverage of a long-range radar with such an antenna pattern. 
 ,  vol. 4, pp. 563–571, 1987. 
 ,Ê," /Ê 
 Let usrecast Eq. (4)ina form appropriate forthis case, introducing explicitly the vertical and horizontal dimensions ofthe antenna aperture, which wedenote byb andarespectively. Toagood enough approximation wecansetb=k/B. 
 The two mixers in Fig. 9.3 may be  single-ended, balanced, or double-balanced mixers. 12 This mixer is capable of wide bandwidth,  and is restricted only by the rrequency sensitivity of the structure of the microwave circuit. 
 The dielectric absorbers are typically made of a  rubbery foam, sometimes urethane, impregnated with carbon particles. Impregnation  may be performed by dipping a compressed slab of material in a graphite suspension  bath, then wringing it out and drying it. Magnetic Dällenbach layers can be rolled from  a mixture of natural or synthetic rubber loaded with carbonyl iron or ferrite powders. 
 cumulative Pd as a function of range for a fixed  radial-velocity moving target1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 20 24 28 32 36 40 Range (nmi )Probability of Detection 44 48 52 56 60Single ScanCumulativ e Target Closes 2 nmi per Sca n ch04.indd   48 12/20/07   4:54:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 Milne, K.: The Cornbination of Pulse Compression with Frequency Scanning for Three-Dimensional  Radars, Radio Electrortic Engr., vol. 28, pp. 89-106, Aug., 1964. 
 757-761,  November, 1972.  40. Weinstock, W.: "Target Cross Section Models for Radar Systems Analysis," doctoral dissertation,  University of Pennsylvania, Philadelphia, 1964. 
 24. Turyn, R.: On Barker Codes of Even Length, Proc. IEEE (correspondence), vol. 
 65. Radford, hl. F.: Frequency Scanning Aerials, Elecfronic Engineerirtg, vol. 
 Tong, P. S.: Quantization Requirements in Digital MTI, IEEE Trans .• vol. AES-13, pp. 
 Frequency scanning inoneangularcoordinate wasthefirstsuccessful electronic scanning technique tobe applied. Interlllsofnumbers ofoperational radars,frequency scanning hasprobably seen moreapplication thananyotherelectronic scanning method. Thefirstmajorelectronically scanned phasedarraysthatperformed beamsteering without frequency scanemployed the Iluggins phaseshifter(Sec.R.4)which.inasense,usedtheprinciple offrequency scanwithout thenecessity ofchanging theradiated frequency. 
 Such aterm unavoidably suggests aparticular type ofdisplay, buta more general andformal terminology seems toocumbersome.. SEC. 210] THESTATISTICAL PROBLEM 39 Let usturn toFig. 
 ING v 0ROC OF )%%% .ATIONAL 2ADAR #ONF .!42!$    3YRACUSE  .EW 9ORK  -AY n     PP n  ! &ARINA  0  ,OMBARDO  AND , /RTENZI  h! UNIFIED APPROACH TO ADAPTIVE RADAR PROCESSING  WITH GENERAL ANTENNA ARRAY CONFIGURATION v 3PECIAL )SSUE ON h.EW TRENDS AND FINDINGS IN  ANTENNA ARRAY PROCESSING FOR RADAR v  3IGNAL 0ROCESSING   %LSEVIER  VOL   NO   PP n   3EPTEMBER   2 # $AVIS  , % "RENNAN  AND ) 3 2EED  h!NGLE ESTIMATION WITH ADAPTIVE ARRAYS IN EXTERNAL  NOISE FIELD v )%%% 4RANS  VOL !%3n  NO  PP n  -ARCH   0 ,ANGSFORD ! &ARINA  , 4IMMONERI  AND 2 4OSINI  h-ONOPULSE DIRECTION FINDING IN PRES 
 If separate antennas are used for transmit  and receive, rv is the width of the receiving antenna and 11' is replaced by h,hr where  it, = transmitting antenna height and /I, = receiving antenna height.  (14.24) (14.25)OTHER RADAR TOPICS535 frequency shiftisproportional tothesquarerootofthecarrierfrequency insteadofthelinear dependence normally characteristic ofadoppler shift. Asthewindspeedincreases. 
 Stable operation occurs for those values ofVand 1which simultaneously satisfy the load and generator characteristics. This would not concern usexcept that the various modes have different V-1characteristics, thus giving cause forinstability. 1The 4J52 magnetron isanexception tothestatement made here, being more stable with arapid rateofrise. 
 easy to make adequate. Short-term stability refers to variations within the round- trip radar echo time or during the signal integration time. The most severe sta- bility requirements relate to the generation of spurious modulation sidebands on the main-beam clutter, which can appear as targets to the target detection cir- cuitry. 
 15.5. The remainder of the block diagram in Fig. 15.3 shows what is necessary for detecting the moving targets so that they may be displayed on a PPI or sent to an automatic target extractor. 
 - 4HIS SECTION DESCRIBES THE GENERATION AND PROCESSING OF PULSE COMPRESSION WAVEFORMS  AND PROVIDES EXAMPLES OF RADAR SYSTEMS THAT UTILIZE THESE PROCESSING TECHNIQUES -AJOR ADVANCES ARE CONTINUALLY BEING MADE IN THE DEVICES AND TECHNIQUES USED IN PULSE COM 
 Tohandlethemaneuver­ ingtarget,somemeansmaybeincluded todetectmaneuvers andchangethevaluesofexandP accordingly. Insomeradarsystems, the·dataratemightalsobeincreased duringtarget maneuvers. Asthemeansforchoosing exandPbecomemoresophisticated, theoptimal ex-p trackerbecomes equivalent toaKalman filterevenforatargettrajectory modelwitherror.In thissense,theoptimal ex-Ptracking filterisoneinwhichthevaluesofexandPrequire knowledge ofthestatistics ofthemeasurement errorsandtheprediction errors,andinwhich ex andparedetermined inarecursive mannerinthattheydependonprevious estimates ofthe meansquareerrorinthesmoothed position andvelocity.79 (Theabovediscussion hasbeenintermsofasampled-data systemtracking targets detected byasurveiJIance radar.Theconceptoftheex-ptrackerortheKalman filteralsocan. 
 The above applies to  single-hit detection. The loss decreases with increasing number of pulses integrated. With 10  pulses integrated, the loss with 10 independent samples decreases to 0.7 dB, and to 0.3 dB for  100 pulses integrated.88  ff the target echo is large, energy can spill over into the adjacent range-resolution cells and  affect the measurement of the average background. 
 21.Spangcnherg. K.R.:"Vacuum Tubes." McGraw-Hili BookCompany, NewYork,1948. 22.Yingst. 
 I. Skolnik (ed.), McGraw-Hill Book Company, New York, 1970.  1.1 Sclll'l[iug. 
 4!",%  .OISE AND $YNAMIC 
 #/5.4%2-%!352%3   Ó{°££ MINOR ERROR CONTRIBUTIONS TO SCATTERED ENERGY RANDOM ERRORS  OR MISDIRECTED RADIA 
 From this range profile, an estimate of the target size can be made.  The profile obtained by the radar is the projection in the direction of propagation. A complete  " image" of the target would require multiple looks from different directions. 
 520 INTRODUCTION TO RADAR SYSTEMS  equal to the one-way pattern of the conventional antenna of the same length, but with one-half  the beamwidth. The two-way patterns with uniform weighting, assuming small angles, are  approximately  SAR-+ sin [2n(Lef).) sin 8]  2n:( Le/ A.) sin 8 sin2 [n(L/l) sin 8]  real array-+ [n(L/1) sin 8J2  Thus the two-way beam width of the SAR antenna is narrower than a real radar antenna of the  same aperture size (if it could be built), but the sidelobes are not as low and do not drop off  with increasing angle as fast. Two-way sidelobes of 13.2 dB in the SAR are not satisfactory for  most purposes. 
 TO 
 RANGE OUT TO  NMI  AIR 
 287. Sensors 2019 ,19, 1154 The results of ship04 are shown in Figure 12, and the results of DCT, PGA and the proposed method are presented in Figure 12b–d, respectively. The focusing of DCT and PGA results produce a certain improvement compared with the original images, but are not well-focused. 
 It has to operate in extreme environmental conditions over an extended temperature  range (down to −40°C in some parts of the world); in high levels of wind, vibration,  and shock; and also in heavy precipitation and salt water spray. Even within the nor - mally benign conditions on the bridge of a large modern ship, the display and radar  processor can be subject to high levels of shock and vibration and must meet high  variations in temperature ( −15°C to +55°C). On small craft, the display and radar pro - cessor are often fitted in minimally enclosed areas and are subject to very damp and  salty conditions. 
 16.10 IMAGING RADAR INTERPRETATION Side-looking fine-resolution imaging radars with real or synthetic apertures pro - duce images that closely resemble aerial photographs. Both shadows and differ - ences in s 0 for different parts of the ground produce image-intensity variations like  those in photographs. For this reason, photointerpreters can easily learn to interpret  radar images. 
 108. D. Atlas, “Advances in radar meteorology,” in Advances in Geophysics , V ol. 
 In civil air transport passenger-  and freight-carrying become uneconomic if undue space  has to be given to radar apparatus, or if its weight is excessive  compared with other navigational equipment.  Technical needs are very different, moreover: in war  aircraft fly very largely over hostile enemy territory,  where it is difficult for navigational aid to be given from  the ground, and where even recognition of ground  targets by systems such as H2S may be confused by radar  . yer  holy  tf  ‘stpttoddiy  ay reresreepititdes  trey  sQeepp  ap  fo  Msopaios  Age . 
 1975.  I 2.1. Knittel. 
 The imaging or the earth's surface by SAR to provide a maplike  display can be applied to military reconnaissance, measurement of sea state and ocean wave  conditions. geological and mineral explorations, and other remote sensing applications.98  The resolution in the cross-range dimension of a conventional antenna is  ( 14.1)  where R is the range and On is the beamwidth. The narrower the beamwidth, the better the  resolution (smaller ,\, ). 
 Chapter 2 defines the usage of these parameters in determin- ing the detectability of signals in a noise background. Dynamic Range. A second useful figure of merit of the front-end device is the dynamic range from rms noise to the signal level that causes 1 dB compres- sion in dynamic gain. 
 TO 
 This capability is known as target classiJication. When the target  is a spacecraft or satellite, the process is sometimes called SOI, or Space Object IdentHcation.  In this section, several possible radar techniques that might be used for target classification  will be enumerated briefly. 
  THICK 'A!S SUBSTRATE 4HE 2& LINES ARE MICROSTRIP 
 20.6  20.2 Derivation of Height from Radar  Measurements  ........................................................  20.14  Flat-Earth Approximation  ...................................  20.14  Spherical Earth: Parabolic  Approximatio n  .......... 
 Pustovoytenko: On Polarization Features of Radio Signals Scattrrcci  From thc Sea Surrace at Small crazing Angles, J. Gc~oplrys. RLJS., vol. 
 One which measures the range and one angle coordinate (usually azimuth)  is called a 2 D radar.  Nodding-beam height finder. Just as the range-azimuth coordinates of a target can be obtained  with a vertical fan-beam antenna, the elevation coordinate can be obtained with a horizontal  fan beam. 
 To maintain a stable closed-loop servosystem for angle tracking, the radar must maintain essentially constant loop gain independent of target size and range. The problem is that monopulse differ- ence signals from the antenna are proportional to both the angle displacement of the target from the antenna axis and the echo signal amplitude. For a given track- ing error, the error voltage would change with echo amplitude and cause a cor- responding change in loop gain. 
 The factorj2nf corresponds to a differentiation. Therefore the optimum  gating waveform appears as the time derivative of the received waveform, if the noise spectrum  is constant. By applying the convolution theorem to Eq. 
 2.Deformed displays. a.Radial deformation ofapolar plot created byashift intherange origin. b.Linear deformation produced by“stretching” apolar plot along one rectangular axis. 
 This chapter concentrates on the requirements and design of radars for commer - cial ships normally in excess of 300 gt (gross metric tonnage), where radar fitment  is compulsory and highly regulated. Worldwide, there are about 50,000 of these ves - sels, and many are required to carry more than one radar. Three or even more radars  are sometimes carried voluntarily by large ships. 
 The LO noise must be removed if  receiver sensitivity is to be maximized. One method for eliminating LO noise that interferes  with the desired signal is to insert a narrow-bandpass RF filter between the local oscillator and  the mixer. The center frequency of the filter is that of the local oscillator, and its bandwidth  must be narrow so that LO noise at the signal and the image frequencies do not appear at the  mixer. 
 SEC. 3,12] SPECULAR ANDDIFFUSE REFLECTIO,V 89 radar system that isused. The identification and correlation are based upon intensity contrasts which fall into se~-eral categories, such asthe contrasts between land and water, between hill and valley, and between built-up areas and open countryside. 
 1–6. 24. C. 
 In practice a re c- tangular pulse is not realizable and this problem does not arise. In fact almost any frequency  modulation and pulse form is used, only if the compression filter is adapted to it, meaning that  it is a matched filter.  Following this the envelo pe of the compressed FM pulse is briefly d e- scribed and derived. 
 Errors of a few meters might not be of significance when 3  cruising at altitudes of 10 km, but are important if the altimeter is part of a blind landing  system.  The theoretical accuracy with which distance can be measured depends upon the band-  width of the transmitted signal and the ratio of signal energy to noise energy. In addition,  measurement accuracy might be limited by such practical restrictions as the accuracy of thc  frequency-measuring device, the residual path-length error caused by the circuits and trans-  mission lines, errors caused by multiple reflections and transmitter leakage, and the frequency  error due to the turn-around of the frequency modulation. 
  AND DIFFERENCE 
 Figure 16.28 shows the improvement factor for an array pointing along the ground track of the aircraft as a function of motion expressed in terms of wave- lengths per interpulse period. The dashed line shows the unadapted single-delay improvement factor for an antenna with a Dolph-Chebyshev aperture illumina- tion that provides a 28 dB uniform peak sidelobe level. The solid line shows the adapted improvement factor to be 92 dB for a stationary antenna, reducing to 89 dB for 4 wavelengths per interpulse-period platform motion. 
 Thepredicted valueoftherangeasfoundfromtheradar equation cannotbeexpected tobechecked experimentally withanydegreeofaccuracy. Itis difficult todetermine precisely alltheimportant factorsthatmustbeincluded intheradar equation anditisdifficulttoestablish asetofcontrolled, realistic experimental conditions in whichtotestthecalculations. Thusitmightnotbeworthwhile totrytoobtaintoogreata. 
 TION  A VERY BAD DETECTION OUTLIER  IS MADE  AND THE FIRM CORRELATION IS DOWNGRADED TO A TENTATIVE CORRELATION IF LIMITING IS NOT USED )F LIMITING IS EMPLOYED  HOWEVER  THE CORRECT DECISION REMAINS FIRM )N A COMPLEX ENVIRONMENT WHERE THERE ARE MANY RADAR TRACKS AND $& SIGNAL SOURCES   IT IS QUITE POSSIBLE THAT MANY $& SIGNALS WILL BE ASSIGNED THE CATEGORY THAT THE $& SIGNAL PROBABLY GOES WITH SOME RADAR TRACK 4O REMOVE MANY OF THESE AMBIGUITIES  MULTISITE $& OPERATION CAN BE CONSIDERED 4HE EXTENSION OF THE PREVIOUS PROCEDURES  &)'52%   0ROBABILITY MARGIN VERSUS NUMBER OF $& DETECTIONS FOR  THREE DIFFERENT TARGET SEPARATIONS 4HE  OS  XS  AND $S ARE THE SIMULATION  RESULTS FOR  L      L     AND  L     RESPECTIVELY AFTER '6 4RUNK AND  *$ 7ILSON Ú )%%%  . 
 TO 
 and T.D.; Formal analysis, C.G.; Data curation, C.G.; writing–original draft preparation, C.G. and T.D.; Writing–review and editing, C.G. and T.D. 
 ANALOG $!  CON 
 The defining characteristic of a sum beam is that it has approximately even symmetry about the beam boresight, while a delta beam has approximately odd symmetry about the same boresight. Without loss of generality, the delta beam may be as- sumed to be adjusted or calibrated to be in phase with the sum beam, in the sense that the ratio of the two patterns is real and odd about the beam boresight versus angle of arrival. Monopulse techniques are classified according to the manner in which the in- cident radiation is sensed, i.e., according to antenna and beamforming tech- niques, and independently according to how the various beams and channels are subsequently processed and combined to produce a target angle estimate.36'37 Amplitude comparison monopulse and phase comparison monopulse are catego- ries of antenna-beamforming sensing techniques. 
 Almost always, tooshort arisetime, t,,ofthevoltage pulse leads tomode instability, any rate ofrise over 100 kv/~sec being considered fast.’ Magnetron sparking can also becaused byhigh rates ofvoit,age rise. A“spike” frequently appears ontheleading edge ofthevoltage pulse. Since amagnetron operates atamagnetic field farabove the nominal cutoff value, itisimpossible forelectrons toreach theanode without the aidofthe r-ffield. 
 Patent 1,981,884, "System for Detecting Objects by Radio," issued to A. H. Taylor, L. 
 DIMENSIONAL  MULTI 
 FT WAVES  ROUGH  %   R   D"  n n n n #HAFF FOR FIXED    WEIGHT PER UNIT    VOLUME G    r  
 1.1 470k -4V60k 2W — P ).2 r~201 * ~Tosynchro rotor t3i~k 6~C, -..---...470k -5V)5 0.5 ~(- 20 look jI/d +16y6AC7 50,u,uf @ T+Trigger--- IL I100k +lCC.J Note Allpartst10%andall resistors; wattunless otherwise specified8.2k 2W1505W: —500 5(xt ,u#f2 -Autoturnoff T — Intensifying ~ gatetoCRT r- 4 Feedback 71- Feedback ampliflerRectangular Area -balanced sweep waveform waveform generator generator FIG.13.50.—Balanced-waveform PPI.. 544 THERECEIVING SYSTEM—INDICATORS [SEC. 13.18 The performance ofthis type ofPPI iscomparable tothat inwhich the transmitter trigger isgenerated automatically. 
 10.20 Distortion tolerances versus time sidelobes.TIME AMP PHASEAMPLITUDE RIPPLE (percent) PHASE RIPPLE (degrees) N 1 2 3 4 5Peak sidelobe, dB - 13.2 - 20.9 - 23.7 - 27.6 -29.6Main-lobe width, -3dB 0.886/J1.02/ri.o8/ri.i4/ri.i6/r*i i 0.5 0.35 0.25 0.300a2 0.5 0.35 0.25 0.225«3 0.30 0.25 0.235«4 0.25 0.170«5 0.070^i 1 1 1 1 1*2 0.55 0.625 0.78 0.72*3 0.350 0.56 0.54b* 0.34 0.36b5 0.18 . FIG. 10.21 Transversal filter. 
 Regardless of the cause of the null, it will show up in the element pattern. If only a few elements surround the central element, the null will normally be shal- low and broad. If many elements are used, the null will be deep and sharp. 
 Inoneexample,40 adispersive delaylinewithalineartime-delay vs.frequency characteristic isfollowed byahardlimiterandbyaseconddispersive delaylinewitha characteristic inversetothefirst.(Ifthelimiterwereomitted, thecircuitwouldoperatesimply asalinearnondispersive timedelay.)Ithasbeenclaimedthattherewasnodiscernible lossin detectability withthisCFAR,butthatthedetectability lossforlog-FTC isabout3dB. Avariation ofthistechnique hasbeenapplied tochirppulse-compression radarto achieveCFARinconjunction withpulsecompression. Twodispersive delaylinesareused withahardlimiterbetween themtoprovideCFAR.Bothlinesareofsimilarcharacteristics, andthetotalpulse-compression ratioisdivided between thetwo.Inonedesign,41 thefirst delaylinecompressed a 5JLSpuIseto1.6/lS,andtheseconddelaylinefollowing thelimiter compressed the1.6JiSpulseto0.05JLS,foratotalpulse-compression ratioof100. 
 ................................ ... 6  Phase Modulation  ................................ 
 1952.  27. Parker. 
 R. Cloude and K. P. 
 NATE FROM THE SAME WAFER EXHIBIT CONSISTENT ELECTRICAL CHARACTERISTICS FROM COMPONENT  TO COMPONENT L 3MALL SIZE AND WEIGHT  )NTEGRATION OF ACTIVE AND PASSIVE COMPONENTS ONTO A  SINGLE CHIP RESULTS IN HIGH 
 The range is found by selecting returns from each of the three segments that satisfy the relations /i</o</2 (17-12) /i + /2 = 2/o (17-13) where/o,/i, and/2 are the frequencies observed during the no-FM, FM-up, and FM- down segments, respectively. The range then is found from Eq. (17.11), where Af = /2 -/o or (/2-/i)/2 or /0 - j\ (17.14) An example is shown in Fig. 
 TION LOSS IN D" AS COMPUTED BY !0- !S A CONVENIENCE FOR THE RADAR ENGINEER  !2%03  WILL ALSO DISPLAY THE !0- OUTPUT IN TERMS OF PROPAGATION FACTOR 4HUS  &IGURE  DISPLAYED IN TERMS OF RADAR PROBABILITY OF DETECTION AS A PERCENTAGE WILL APPEAR AS SHOWN IN &IGURE  WHEN DISPLAYED IN TERMS OF PROPAGATION FACTOR )N ADDITION TO THE DEFAULT HEIGHT VERSUS RANGE DISPLAY  !2%03 CONTAINS MANY OTHER  DISPLAY AND DATA OUTPUT OPTIONS &OR EXAMPLE  &IGURE  SHOWS FOR THE SAME MISSILE DETECTION EXAMPLE  A SIGNAL 
 Radar System Engineering  Chapter 9 – Synthetic Aperture Radar  85     To this is added the respective offset resulting from the linear FM modulation within the a n- tenna beam -width, which contains the actual information.  T his means that the reception spe c- trum shifts towards the transmission spectrum, as shown in Figure  10.9.    Figure 10.9  Transmission and reception spectrum. 
 STEP &OURIER TECHNIQUE PROVIDES A VERY ROBUST MODEL FOR COMPLICATED REFRACTIVITY STRUCTURES FOR WITHIN  NEAR  AND BEYOND THE HORIZON EFFECTS AND IS PARTICULARLY GOOD FOR PROPAGATION OVER IRREGULAR TERRAIN 4HUS  0% MODELS ALLOW FOR A SINGLE MODEL ASSESS 
 3TAND /FF *AMMER.   %,%#42/.)# #/5.4%2 
 Cheston, a pioneer in phased array antennas. ch13.indd   1 12/19/07   2:31:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 2, pp. 6--13,  Summer, 1975.  7. 
 Resolution of the unambiguous doppler-velocity  is needed for medium-PRF waveforms, and it is generally done with a similar unfolding  and correlation technique, as described previously for range ambiguities. As shown in  Figure 4.19, velocity unfolding of detections involves adding a set of signed integers  0 2 PRF1 Vel PRF1 Vel - PRF1 Vel 0 PRF2 Vel - PRF2 Vel PrfVel = PRF Velocity = fR λ/2 AmbVel = Ambiguous velociy = PrfVel * Fcentroid /NFFTAmbVel1Correlated  Doppler-velocity AmbVel2 FIGURE 4.19  Doppler-velocity correlation performed on two detections across two looks. Ambiguous  detections are unfolded out to a maximum positive and negative velocity . 
 SHIP BETWEEN RADAR AND OCEANOGRAPHY HAS GROWN UP IN THE FIELDS OF REMOTE SENSING  LEADING TO THE ACCUMULATION OF A LARGE AMOUNT OF INFORMATION  BOTH EXPERIMENTAL AND THEORETICAL  ABOUT HOW SCATTERING AT RADAR FREQUENCIES RELATES TO OCEANOGRAPHIC VARIABLES )N MANY WAYS  THIS INFORMATION SERVES AS THE BASIS OF MUCH OF OUR CURRENT UNDERSTANDING OF SEA CLUTTER )N MODELING SEA CLUTTER  THERE IS A DIFFERENCE BETWEEN A  THEORY  WHICH RELATES THE  PHYSICAL SCATTERING PROPERTIES OF THE SEA SURFACE TO THE RECEIVED SIGNAL  AND A  CHARAC 
 Monitoring devices are usually  included to ensure that the transmitter is delivering the proper shape pulse at the proper  power level and that the receiver sensitivity has not degraded. Provisions may also be in-  corporated in the radar for locating equipment failures so that faulty circuits can be easily  found and replaced.  Instead of displaying the " raw-video" output of a surveillance radar directly on the CRT,  it might first be processed by an'autornaticdetection and tracking (ADT) device that quantizes  the radar coverage into range-azimuth resolution cells, adds (or integrates) all the echo pulses  received within each cell, establishes a threshold (on the basis of these integrated pulses) that  permits only the strong outputs due to target echoes to pass while rejecting noise, establishes  and maintains the tracks (trajectories) of each target, and displays the processed information  6INTRODUCTION TORADAR SYSTEMS , -~ (a) (b) Figure1.3(a)PPIpresentation displaying rangevs.angle(intensity modulation); (0)A-scop~ pr~senta­ tiondisplaying amplitude vs.range(deflection modulation). 
 ATIONAL AWARENESS IS SUFFICIENT AND HIGH ACCURACY IS NOT REQUIRED 3EARCH 4HE TWO PRIMARY SEARCH MODES ARE  !UTONOMOUS 3EARCH  AND #UED 3EARCH  )N !UTONOMOUS 3EARCH THE OPERATOR SELECTS A RANGE  AZIMUTH  AND ELEVATION COVERAGE  AND THE RADAR SEARCHES EACH BEAM POSITION THAT COVERS THIS VOLUME ONCE PER FRAME 4HE TIME IT TAKES TO COMPLETE A FRAME IS KNOWN AS THE REVISIT OR FRAME TIME 4HE  FRAME TIME  SHOULD BE MINIMIZED TO ENHANCE THE CUMULATIVE PROBABILITY OF DETECTION OF TARGETS -ODERN RADAR SYSTEMS CAN TAKE ADVANTAGE OF ON 
 Additive noise sources can be external to the radar, such as atmospheric noise  (sky temperature), ground noise (black body radiation), and jammers, or they can be  internal, such as thermal noise. Thermal noise is also known as Johnson noise  and  3 dBq 0 dBq66 dBq 63 dBq 56 dBq RMS Thermal Noise at A/D53 dB Mean C/ NMAXMaximum Peak Sinsusoidal Level (A/D Sat)  Maximum RMS Sinsusoidal Level (A/D Sat) 10 dB Clutter Fluctuation Headroom 63 dB  Peak A/D Dynamic Range Gated Phase Noise Power4 dB MarginIntegrated Discrete Level at CFAR Total Integration Gain Discrete Level Requirement−60 dBc −56 dBc3 dBc 0 dBc FIGURE 4.16  Dynamic range and stability levels ch04.indd   27 12/20/07   4:52:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Skolnik (ed.), McGraw-Hill  Book Company, New York, 1970.  22. Paoli, L.: Sea Clutter Cancellation & Attenuation in Modern Marine Radars, Rivisra Teoriu Srlrnia,  (Rome, Italy), vol. 
 J. Roy. Meteor. 
 Its occurrence is rare. The term anomalous, or nonstandard, propagation  applies to any of the above propagation conditions other than normal; but it is almost always  used to describe those conditions where the radar range is extended well beyond normal.  A superrefracting duct which lies close to the ground is called a ground-based duct, or a  sw(ace duct. 
 ● Calibration  (Curlander et al.,4 Chapter 7) refers to the use of targets of known radar  cross section (RCS) in the scene to obtain the absolute level of RCS per pixel and  thus s  0, the ground RCS per unit area. ● Geolocation  (Curlander et al.,4 Chapter 8) is the process of determining the absolute  latitude and longitude of pixels in the SAR image, typically using information from  the GPS. ch17.indd   15 12/17/07   6:49:09 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 BEAM AMPLIFIER )N THE PAST  THERE MIGHT HAVE BEEN DEBATE AS TO WHETHER TO USE AN OSCILLATOR OR AN  AMPLIFIER FOR A HIGH 
 POWER MICROWAVE TUBES BY SOLID 
 LENGTH ABOVE THE METAL SURFACE AND ORIENTED AT  RELATIVE TO THE 2& ENERGY REFLECTED FROM THE PARABOLOID 4HE 2& ENERGY MAY BE VISUALIZED AS BEING COMPOSED OF A COMPONENT PARALLEL TO AND REFLECTING FROM THE GRID AND A COMPONENT PERPENDICULAR TO AND PASSING THROUGH THE GRID TO REFLECT FROM THE METAL MIRROR SURFACE BELOW "Y TRAVELING THE QUARTER WAVESPACE TWICE  THIS COMPONENT IS SHIFTED BY  IN PHASE 7HEN ADDED TO THE REFLECTION FROM THE GRID  IT RESULTS IN A  CHANGE IN POLARIZA 
 Testa and V . Vannicola, “The physical significance of the eigenvalues in adaptive arrays,”  Digital Signal Processing , vol. 15, pp. 
 Large vibrators, capable ofsupplying 200 watts ormore from 12-to14-volt or24-to28-volt d-c supplies, areavailable, but itisusually more. convenient touse conven- tional inverters with transformer-rectifier power supplies for outputs greater than 250 watts. Vibrator power supplies usually give efficiencies of50to70percent, based ond-coutput vs.d-cinput. 
 Most radar antennas are linearly polarized; that is, the direction of the electric field  vector is either vertical or horizontal. The polarization may also be elliptical or circular.  Elliptical polarization may be considered as the combination of two linearly polarized waves  of the same frequency, traveling in the same direction, which are perpendicular to each other in  space. 
 SCAN COMPEN 
 Williams, Jr., “Radar return at near-vertical incidence,” Proceedings of  the IRE , vol. 45, pp. 228–238, 1957. 
 The decision between 3000 and 10,000 Me/see was based largely upon thefact that inthelatter case waveguide ofaconvenient size could beused, anextremely desirable design feature. Since a32-mile range isadequate forthe uses intended, and since too great sharpness ofbeam might lead toalignment difficulties, 3-ft parabo- loids were used atboth stations. Frequency modulation was chosen, partly because ofitsadvantages when signal-to-noise and signal-to-interference ratios arehigh, but mostly because itsimplified the oscillator design. 
 FILTER OUTPUT IS LINEARLY SUMMED OVER SEVERAL #0)S &OR EACH RANGE 
 J. G. Proakis and D. 
 Theory 2006 ,52, 489–509. [ CrossRef ] 22. Li, S.Y.; Zhao, G.Q.; Li, H.M.; Ren, B.L. 
 TAP &)2 FILTER IN A MICROPROCESSOR WITH A SINGLE MULTIPLIER AND ACCUMULATOR  IT WOULD TAKE  CLOCK CYCLES TO PERFORM THE MULTIPLICATIONS )N AN &0'!  WE COULD ASSIGN  MULTIPLIERS AND  ACCUMULATORS TO THE TASK  AND THE FILTER COULD BE PERFORMED IN ONE CLOCK CYCLE.   2!$!2 $)')4!, 3)'.!, 02/#%33).'   Óx°ÎÇ )N ORDER TO USE AN &0'! MOST EFFICIENTLY  WE HAVE TO TAKE ADVANTAGE OF ALL OF  THE RESOURCES IT OFFERS 4HESE INCLUDE NOT ONLY THE LARGE NUMBERS OF LOGIC ELEMENTS   MULTIPLIERS  AND MEMORY BLOCKS  BUT ALSO THE RATE AT WHICH THE COMPONENTS CAN BE CLOCKED )N THE PREVIOUS EXAMPLE  ASSUME THAT THE DATA SAMPLE RATE IS  -(Z AND ALSO ASSUME THAT THE MULTIPLIERS AND LOGIC CAN BE CLOCKED AT  -(Z )F WE SIMPLY ASSIGN ONE MULTIPLIER TO EACH COEFFICIENT  WE WOULD USE  MULTIPLIERS  CLOCKING AT  -(Z  3INCE THE DATA RATE IS ONLY  -(Z  EACH MULTIPLIER WOULD ONLY PERFORM ONE SIGNIFICANT MULTIPLICATION EVERY MICROSECOND AND THEN BE IDLE FOR THE OTHER  CLOCKS IN THE MICROSECOND  WHICH IS VERY INEFFICIENT )T WOULD BE MUCH MORE EFFICIENT  IN THIS CASE  TO USE ONE MULTIPLIER TO PERFORM AS MANY PRODUCTS AS POSSIBLE 4HIS TECHNIQUE  CALLED  TIME 
 44, pp. 2203–2226, 1965. 110. 
 Figure8.31,fromWeinstock, 120isanexample ofthetimingofeventsthatmustoccurin radartransmission andreception. Thebottomfigureshowsthetimingoftheradartransmis­ sions.Whiletheradarisstillreceiving echoesfromthe(N-l)stdwell,ablockofcommand wordsiscommunicated totheradarforcontrol oftheNthdwellandthebeam-steering computer calculates thephase-shifter ordersneededforthenexttransmission. Afterthetimeof themaximum rangereturnhaselapsed, thephaseshifterscanbesetforthenexttransmission. 
 TRACING AND MODELED ANTENNA PATTERNS  TO DEMONSTRATE THAT THE DIRECTIONAL VARIABILITY OF NOISE  COUPLED WITH THE DIRECTIONAL CHARACTERISTICS OF DIFFERENT ANTENNAS  CAN LEAD TO MARKED CHANGES IN NOISE OUTCOMES AND HENCE IN OPTIMAL RADAR DESIGN !NOTHER IMPORTANT ISSUE IS THE BEHAVIOR OF THE EXTERNAL NOISE FIELD AS A FUNCTION OF  TIME  THAT IS  WITHIN THE COHERENT INTEGRATION INTERVAL SINCE THIS IMPACTS STRONGLY ON SIGNAL PROCESSING FOR INTERFERENCE REJECTION  /THER EFFECTS THAT CAN INFLUENCE RADAR  PERFORMANCE ARE SOMETIMES MISTAKEN FOR THE ADDITIVE  NOISE DISCUSSED ABOVE /NE OF  &)'52%   .OISE POWER PER HERTZ IS GIVEN FOR g NORTH LATITUDE AND g WEST LONGITUDE IN WINTER  A   54# IS GIVEN AS A DAYTIME EXAMPLE AND B   54# IS GIVEN AS A NIGHTTIME EXAMPLE. 
 measured at this angle by a number of investigators at X band (see Ref. 12), showing a similarity between the returns at these two widely spaced frequencies. However, at lower frequencies, at L band and below, there is a noticeable ten- dency for the cross section to fall off with decreasing grazing angles below about 15 to 20°. 
 Becauseofitsmanyradiating elements, anarrayantenna isbettersuitedfor achieving thelow-sidelobe aperture illumination thanisareflector. Firstsidelobes offrom40 to50dBbelowthemainbeammaybepossible withtheproperaperture illuminations andthe propercareinimplementation. Ahigh-gain antenna isusuallynecessary toachievesuchlow sidelobes. 
 The switch selects either the vertical or the horizontal input com- ponent or combines them with a 90° relative phase for circular polarization. This feed does not provide optimum sum- and difference-signal E fields because the sum horn occupies space desired for the difference signals. Generally an under- sized sum-signal horn is used as a compromise. 
 B-Sandwich . In contrast to the A-sandwich, the B-sandwich is a three-layer con - figuration whose skins have a dielectric constant lower than that of the core material.  This wall cross section is heavier than that of the A-sandwich because of the relatively  dense core. 
 16.4 Normalized boresight-velocity ratio VBR as a function of the difference between slant range Rs and aircraft altitude H for different aircraft altitudes.VBR . function of slant range for a curved earth and different aircraft altitudes. The vari- ation is fairly rapid for slant ranges less than 15 mi. 
 Itsfunction isto accept r-fenergy from thetransmission line, todistribute this energy into space asdesired, togather intheradar echoes ofthis energy, and todirect these echoes back into thetransmission line. Since the nature ofelec- tromagnetic radiation issuch that agood transmitting antenna isalso a good receiving antenna, weneed consider only theformer function. In most cases theantenna isrequired toform theenergy into asharp beam which may beaimed invarious directions. 
 END 34!0 WILL NOT DIRECTLY ADDRESS CLUTTER INTERNAL MOTION EFFECTS  ANTENNA SCANNING MOTION EFFECTS  OR OTHER HARDWARE STABILITY IMPACTS TO CLUTTER CANCELLATION PERFORMANCE 2ADAR DESIGNERS NEED TO ASSESS THE KEY LIMITATIONS IN A SPECIFIC APPLICATION BEFORE JUMPING TO THE CON 
 Nooff-centering isused with the 3-phase system ofFig. 13.48; when+mitisdesired, 2-phase windings are more suitable. TheUseojSpecial Wavejorms. 
 LEVEL SIGNAL DUE TO THIS LARGE 2#3 AND THOSE MUCH SMALLER SIGNALS DUE TO TARGETS  ESPECIALLY WHEN THE LATTER ARE ADJACENT TO THE STRONGEST CLUTTER COMPONENTS !N (& RADAR MUST BE DESIGNED TO ACCOMMODATE SUCH CLUTTER LEVELS EVEN THOUGH  THEY WILL NOT EXIST ALL THE TIME  OR AT ANY ONE TIME  OVER ALL AREAS  ESPECIALLY AT THE LOWER OPERATING FREQUENCIES %STIMATION OF 3EA 3TATE  7AVE 3PECTRA  AND 3URFACE 7INDS  4ECHNIQUES FOR  EXTRACTING OCEAN WAVE FIELD INFORMATION FROM MEASURED DOPPLER SPECTRA HAVE BEEN REPORTED BY NUMEROUS AUTHORS  WORKING  IN ALMOST ALL CASES FROM  THE "ARRICK SOLUTION  FOR THE SCATTERED FIELD AND DEALING ALMOST EXCLUSIVELY WITH (& SURFACE WAVE RADAR DATA  UNCORRUPTED BY IONOSPHERIC PROPAGATION )NVERSION OF THE RELATION IN %Q  TO OBTAIN AN ESTIMATE OF  3 FJ IS MATHEMATICALLY NONTRIVIAL  REQUIRING SOME ADDITIONAL  ASSUMPTIONS TO OBTAIN A UNIQUE  STABLE SOLUTION 3OME OF THESE METHODS ADDRESS THE PROBLEM OF FULL DIRECTIONAL WAVE SPECTRUM ESTIMATION  n WHEREAS OTHERS PROPOSE  ESTIMATORS FOR INTEGRATED MEASURES OF SEA ROUGHNESS SUCH AS SIGNIFICANT WAVEHEIGHT     
 FERENCE BY FILTERING IN POLARIZATION SPACE ANY SIGNALS CORRELATED WITH THOSE RECEIVED ON AN AUXILIARY HORIZONTALLY POLARIZED RECEIVE ANTENNA CAN BE CANCELLED FROM THE OUTPUTS OF THE VERTICALLY POLARIZED ARRAY u 4HE INCREASINGLY RAPID ATTENUATION OF PROPAGATION TO RANGES BEYOND ABOUT  KM  AS SHOWN IN &IGURE   MEANS THAT AT LONGER RANGES  RELATIVELY LITTLE DETECTION PERFORMANCE IMPROVEMENT IS GAINED BY LARGE INCREASES IN TRANSMITTED POWER u 4HE RATE OF DECAY OF THE SURFACE WAVES RISES SHARPLY WITH INCREASING FREQUENCY  AS SHOWN IN &IGURE   WHEREAS THE 2#3 OF SMALL TARGETS TENDS TO INCREASE RAPIDLY AND EXTERNAL NOISE DECREASES )T FOLLOWS THAT RADAR DESIGN IS SENSITIVE TO THE CLASSES OF TARGETS TO BE DETECTED u 7HILE (&372 DOES NOT RELY ON THE IONOSPHERE  ECHOES FROM IRREGULARITIES IN THE IONOSPHERE MAY APPEAR AT RANGES IN EXCESS OF ^ KM  3IMILARLY  GROUND REFLEC 
 A wide variety of plasma waves and instabilities  populate these regions, producing irregularities that achieve high electron densities  and hence, provide strong sources of spread-doppler clutter. They have been known to  impact skywave radar systems severely. Ionospheric Variability. 
 6. Dupuis, X.; Martineau, P . Very high resolution circular SAR imaging at X band. 
   PP n  *UNE    2 3 "ERKOWITZ ED    -ODERN 2ADAR !NALYSIS  %VALUATION AND 3YSTEM $ESIGN   .EW 9ORK   *OHN 7ILEY  3ONS     $ + "ARTON  2ADAR 3YSTEMS !NALYSIS  %NGLEWOOD #LIFFS  .* 0RENTICE 
 ELEMENT FEED  AS SHOWN IN &IGURE  (OWEVER  SOME APPLICATIONS USE MORE FEED ELEMENTS TO FURTHER TAILOR THE DISTRIBUTION TO IMPROVE EFFICIENCY ANDOR DIFFERENCE BEAM SLOPE )F THE REFLECTOR IS ILLUMINATED WITH A SIMPLE FOUR 
 Eng., vol. 93, pt. illA,  pp. 
 OE-2, pp. 200–206, 1977. 134. 
 The former denotes complicated targets (such asships, air- craft, and structures) which arelarge, butstill smaller than theilluminated region. The power received from compound targets isthus dependent onbeamwidth and pulse length, since these govern the size ofthe pulse packet; thesignal from acomplex target isnot. 3.8. 
 Atlantic Coast of the United States (Area 1). Ducting is common in summer along the northern part of the coast, but in the Florida region theseasonal trend is the reverse, with a maximum in the winter season. Western Europe (Area 2). 
 RANGE RESOLUTION 3!2 OPERATING IN BURST MODE CAN CHANGE ITS CENTRAL FREQUENCY FROM ONE LOOK TO ANOTHER  WITHOUT ANY DEGRADATION IN IMAGE QUALITY 'IVEN THE EFFICIENCY OF SIMPLE BROADBAND JAMMING AND MODERN %3-  WE NEED TO CONCLUDE THAT FREQUENCY AGILITY IS NOT OF GREAT HELP IN 3!2 %##- u 0ULSE CODING  !N EFFECTIVE %##- AGAINST A $2&- REPEAT JAMMER IS TO CHANGE  THE RADAR TRANSMITTED PULSE CODE FROM ONE 02) TO ANOTHER 4HE RADAR MAINTAINS THE SAME CARRIER AND BANDWIDTH HOWEVER  THE PULSES ARE CODED TO BE APPROXI 
 When limiting is employed, there can be small-target  suppression and possibly spurious false-targets as well. The long uncompr-essed pulse can  restrict the minimum range and the ability to detect close-in targets. A conventional short  pulse at a different frequency might have to be generated at the end of the·Jong pulse to provide  coverage of the close-in range that is blanked by the long pulse. 
 12.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 A relatively simple way to shape the beam is to shape the reflector, as Figure 12.20  illustrates. Each portion of the reflector is designed to reflect a portion of the inci - dent energy in a different direction, and to the extent that geometric optics is valid,  the power density at that angle is the integrated sum of the power density from the  feed across that portion of the reflector. Silver13 graphically describes a procedure for  determining the reflector contour for a cosecant-squared beam. 
 ITY IS  'BITS DOWNLINK MAXIMUM DATA RATE IS  -BITSS 8  BAND  DUAL CIRCULARLY  POLARIZED  4HE 2)3!4 ORBIT IS SUN 
 Cutler. C. C.: Parabolic-antenna Design for Microwaves, Proc. 
 CONTROLLED DEVICE WITH THE COLLEC 
 17.15). This method issomewhat less susceptible tointerference effects than Method 2since more data are sent perradar cycle and since anextra pulse does notcause anirreversible effect. The method ofrelaying sine and cosine data bypulse-timing tech- .. 
 Collings, “Current sheet antenna,” U.S. Patent 3,680,136, 1972. 25. 
 TIONAL -4) AND PULSE DOPPLER PROCESSING ARE NOT APPLICABLE )T IS WELL KNOWN THAT THE CLASSICAL SINGLE 
 This might be possible in a rapidly scanning radar, but with tracking radars or illuminators the indicated bandwidths would be unrealistically narrow. Moreover, the target itself seldom produces a clearly defined doppler but, rather, a spread of frequencies by the scintillation and glint effects. Bandwidth may also have to be allowed for the coding frequencies which may accompany the doppler, such as those injected by conical scan. 
 RADAR DIGITAL SIGNAL PROCESSING  25.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 Consider a system with a 5-MHz reference oscillator, from which is derived a  75 MHz IF center frequency (on transmit and receive) and a complex sample rate  of 30 MHz. A rule of thumb is that the clock used to produce the pulse repetition  interval (PRI) needs to be a common denominator of the IF center frequencies on  transmit and receive and the complex sample frequency in order to assure pulse-to- pulse phase coherency. For this example, with an IF center frequency of 75 MHz and  a complex sample rate of 30 MHz, allowable PRI clock frequencies would include  15 MHz and 5 MHz. 
 C'.. C'. K. 
 TO 
 35.Ronchi,L.,andG.Toraldo diFrancia: AnApplication ofParageometrical OpticstotheDesignofa Microwave Mirror,IRETrans.,vol.AP-6,pp.129-133, January, 1958. 36.Provencher, J.H.:Experimental StudyofaDiffraction Reflector, IRETrtms., vol.AP-~, pp.331-336, May,1960. 37.Kelleher, K.S.:ANewMicrowave Reflector, IRENatl.COnti.Record,vol.I,pt.2,pp.56..58,1953. 
 These trades are shown in detail in Refs. 12 and 13.20° SCAN 0° SCANSPACE FEED THEORY SIMULATION RESULTSRELATIVEGAIN (dB) . ALUMINUM SHIELDING THICKNESS (mils) FIG. 
 The elevation angle 6 is referenced to the crossover point halfway between the beam peaks. This normalization re- moves the aperture dimension L and transmit wavelength X from the performance of the technique. The figure shows that the sensitivity factor peaks at crossover and is symmetrical about the crossover angle. 
 From Eq. (9.12b) the noise figure of the mixer is Fc = r, LC. This, however, is not a  complete measure of the sensitivity of a receiver with a mixer front-end. 
 PIs are typically used  to ensure that a ship is maintaining a safe ground track, with reference to a ground-fixed  conspicuous radar target. Chart Radars.  The capability and relatively low cost of modern processing and  display systems allow great flexibility in the presentation of information to users. 
 The difference between the position measured by the optics and that  180INTRODUCTION TORADAR SYSTEMS Precision" on-axis" tracking.62-65Someofthemostprecisetracking radarsarethoseasso­ ciatedwiththeinstrumentation usedatmissile-testing ranges.62Onesuchclassofprecision tracking radarhasbeencalledon-axistracking.OJTheoutputofaconventional servosystem lagsitsinput.Theresultofthelagisatracking error.Theon-axistrackeraccounts forthislag, aswellasforotherfactorsthatcancontribute totracking error,soastokeepthetargetbeing trackedinthecenterofthebeamoronthenullaxisofthedifference pattern.On-axis tracking, ascompared withtrackers withatargetlag,improves theaccuracy byreducing thecoupling between theazimuth andelevation angle-tracking channels, byminimizing thegeneration of crosspolarization andbyreducing theeffectsofsystemnonlinearities. Theprocesses thatconstitute on-axistracking include(1)theuseofadaptive tracking whoseoutputupdates astoredprediction ofthetargettrajectory ratherthancontrol the antenna servodirectly, (2)theremoval bypriorcalibration ofstaticanddynamic system biasesanderrors,and(3)theuseofappropriate coordinate systems forfilteriqg (smoothing) thetargetdata. Theradar'sangle-error signalsaresmoothed andcompared toapredicted measurement basedonatarget-trajectory modelupdated by'theresultsofprevious measurements. 
 WAVE REFRACTOMETER ONBOARD SOME SORT OF AIR VEHICLE (OWEVER  FOR AN EVAPORATION DUCT  IT IS NOT THE VERTICAL EXTENT OF THE DUCT THAT IS IMPORTANT BUT THE REFRACTIVE GRADIENT WITHIN THE DUCT #HANGES OF REFRACTIVE GRADIENTS OVER VERTICAL HEIGHTS LESS THAN A FEW MILLIMETERS MAY HAVE A SIGNIFICANT IMPACT UPON THE DUCTS TRAPPING ABILITY 4HUS  ASSESSMENT OF THE EVAPORATION DUCT IS BEST PERFORMED BY MAKING SURFACE METEOROLOGICAL MEASUREMENTS AND INFERRING THE DUCT HEIGHT FROM THE METEOROLOGICAL PROCESSES OCCURRING AT THE AIRSEA INTER 
 This interest has been  heightened by the jamming that threatens most military radars. The requirement for  low sidelobes for clutter rejection in the AWACS radar resulted in technology that now  supports sidelobe levels of more than 50 dB below the main-beam peak.62,63 The price  that must be paid to achieve these low sidelobes includes (1) a reduction in gain, (2) an  increase in beamwidth, (3) increased tolerance control, (4) increased cost, and (5) the  need to operate in an environment free from obstructions that can readily increase the  sidelobes.64 In spite of these drawbacks, the trend to low-sidelobe antennas has accel - erated since low sidelobes provide a counter to electronic countermeasures (ECM). Antenna sidelobes can be controlled by the aperture amplitude distribution. 
 TION )N EVALUATING BISTATIC RADAR OPERATION  IT IS USEFUL TO START WITH A GEOMETRY 
 DIGITAL CONVERTER= NOISEv P   4HE MULTIPLICATIVE NOISE RATIO -.2   OF A 3!2 IMAGE IS DEFINED AS THE RATIO OF THE  IMAGE INTENSITY IN  NO 
 1967.  58. Worley, R.: Optimum Thresholds for Binary Integration, IEEE Trans., vol. 
 /- /F CONCERN HERE ARE ERRORS PECULIAR TO PHASED ARRAYS  WHICH ARE DUE TO THE QUANTIZATION  OF AMPLITUDE AND PHASE AND TO THE LOBES THAT OCCUR WHEN THESE ERRORS ARE REPEATED PERI 
 Therefore the probability of the event y may be ex-  pressed as  P(Y) = P(Y I SN)P(SN) + P(Y I N)P(N) (10.29)  The a posteriori probability of Eq. (10.23) becomes  Or, in terms of the likelihood ratio3'  Therefore, if a receiver can be built which computes the likelihood ratio and if the a priori  probability p(SN) is known, the a posteriori probability can be calculated. Since ~(sNJ~) is a  rnonotonic function of Lr(y), the output of the likelihood receiver (or the matched-filter  receiver) can be calibrated directly in terms of the a posteriori probability. 
 R. C. Johnson, H. 
      WHERE - IS AN INTEGER GREATER THAN  4HUS  OPTIMUM SAMPLING RATES ARE   F)&    F)&    F)&    F)&  x ETC 4HE CORRESPONDING MAXIMUM UNALIASED OR .YQUIST  BANDWIDTH  IS "F.1 !$  4HIS VALUE IS  THEREFORE  THE MAXIMUM ALLOWABLE CUTOFF BANDWIDTH OF  THE )& BANDPASS FILTER AT THE INPUT TO THE !$ CONVERTER )T IS NOT STRICTLY NECESSARY TO USE  .   -4) 2!$!2  Ó°Ç AN !$ CONVERTER SAMPLING RATE AS GIVEN BY %Q   BUT OTHER VALUES WILL RESULT IN AN   AVAILABLE .YQUIST BANDWIDTH LESS THAN  F!$ 4HIS IS SHOWN IN &IGURE  WHERE  THE NORMALIZED .YQUIST BANDWIDTH IS SHOWN AS A FUNCTION OF THE RELATIVE !$ CONVERTER  SAMPLING RATE &ROM THIS FIGURE  IT IS SEEN THAT THE DIRECT CONVERSION APPROACH WILL FAIL WHENEVER A VALUE OF -  WHICH IS LOCATED HALFWAY BETWEEN THE OPTIMUM VALUES  IS USED !T THE !$ CONVERTER OUTPUT  THE SIGNAL SAMPLES ARE STILL REAL VALUED 4O BE ABLE  TO EXTRACT THE COMPLEX ENVELOPE CORRESPONDING TO THE POSITIVE PART OF THE SPECTRUM    
 607-615, September 1976. 17. Applebaum, S. 
 Fung, “Radar determination of winds at sea,” Proceedings of the IEEE ,  vol. 67, pp. 1504–1521, 1979. 
 Homing aerials on a Hudson (ARI 5077, homing aerials only) [ 7].Airborne Maritime Surveillance Radar, Volume 1 2-9. A high-power transmitter, T.3140, and a separate modulator, type 52, was introduced into service in the spring of 1943 (ARI 5205). This was designated ASV Mk. 
 The magnitude of the echo may be determined by finding the polygo - nal areas on each face of the corner receiving waves reflected by the other faces and  from which the final reflection is back toward the source. The effective area is deter - mined by summing the projections of the areas of those polygons on the line of sight11;  the RCS is then found by squaring that area, multiplying by 4 p, and dividing by l2. Figure 14.8 is a collection of RCS patterns of a trihedral corner reflector with  triangular faces. 
 860 862, September. 1948.  66. 
 The usual design  procedure is to compute the ambiguity diagram for the more common wav'eforms and to  observe its behavior. Because of the limitations of synthesis, the ambiguity diagram has been  more a measure of the suitability of a selected waveform than a means of finding the optimum  waveform.  Single pulse of sine wave. 
 speeds well beyond those which would normally disperse the lighter natural oils; so the effect of oil spills on sea clutter should be expected to extend to the higher wind speeds. In fact, at these higher wind speeds the depression of radar backscatter by such oils at X and Ka bands can reach 10 to 20 dB at intermediate grazing angles between 30 and 60°.67'68 Currents. The most obvious effect of a current on sea clutter would be a shift in the peak of the doppler spectrum, similar to the contribution of the 3 percent wind-drift current mentioned in connection with Eq. 
 SIDEBAND POWER SPECTRAL DENSITY OF THE PHASE NOISE AS  A FUNCTION OF FREQUENCY FROM THE CARRIER  3ECOND  INCREASE THIS SPECTRAL DENSITY BY   D" 4HIS ACCOUNTS FOR A  
 90. Deirmendjian. D.: Far-Infrared and Submillimeter Wave Attenuation by Clouds and Rain, J. 
 The camera shutter was left open for three scans of the antenna; thus, aircraft show up  as a succession of three returns. MTI radar utilizes the doppler shift imparted on the  reflected signal by a moving target to distinguish moving targets from fixed targets. In  a pulse radar system, this doppler shift appears as a change of phase of received sig - nals between consecutive radar pulses. 
 Angle-data Transmitters.—Thc devices that provide the scanner data are known as“(angle) data transmitters.” ‘~hey in-. SEC. 13.4] ANGLE-DATA TRANSMITTERS 487 elude potentiometers, variable transformers, variable condensers, and generators. 
 pp. 88 -95. February. 
 Transmission takes place only on  the lower of the two beams. At short range, reception is on the upper heam only. This heam is  tilted to minimize illumination of the ground. 
   PP n  3EPTEMBER   - $ /,EARY AND %RIC 3CHULZINGER   32 
 M RESOLUTION AT  LOOKS 4HE -INI 
 = R4th + Lo = Frequency* = El. Angle ^ 1 deg.* = NoiseAPRSSN= 1OTlME = ISGMTUOCATION 38.65 N LAT 76.53 W LON BEARING= 90.00 DEGAPR SSN = 100 TIME = 18 GMTLOCATION 38.65 N LAT 76.53 W UON BEARING= 90.00 DEG Ground Range (nmi) (b) FIG. 24.22 Radar performance estimate; April, 1800 UTC. 
 D. L.: Detection of Sea Ice Growlers by Radar, IEE Cot!/: Pirhl. no. 
 83. van der Maas, G. J.: A Simplified Calculation for I>olpl~-Tsct~ebyscllsff Arrays, J. 
 790 803, August, 1956.  70. ap Rliys. 
 The autocorrelation function of  a rectangular pulse of width r is a triangle whose base is of width 2.r.  Efficiency of nonmatched filters. In practice the matched filter cannot always be obtained  exactly. 
 Data stabilization is not necessary if a three-axis mount is used, such as e or f of  Fig. 7.3 l.  Nine possible arrangements for mounting antennas are shown in Fig. 
 DERIVATIVE 
 Passive generation involves exciting a device or network with a short pulse to produce a time-expanded coded waveform. An example is an expansion network composed of a surface-acoustic- wave (SAW) delay structure. Active processing involves mixing delayed replicas of the transmitted signal with the received signal and is a correlation-processing . 
 The str.cJps (7) are metal rings connected to alternate segments of the anode block. They  in~lxove the stability and efficiency of the tube. The preferred mode of magnetron operation  corresponds to an RF field configuration in which the RF phase alternates 180" between  adjacent cavities. 
 These categories overlap in some respects, but it is convenient to separate  the noise in these two frequency ranges because they are generated by different phe - nomena, and they are each significant to different functions of the radar. Low-Frequency Amplitude Noise.  The low-frequency amplitude noise is the time  variation of the vector sum of the echoes from all the reflecting surfaces of the target. 
 Passive bistatic radar performance is subject to  degradation by radio frequency interference (RFI) from both the exploited broadcast  transmitter and other emitters in spatial or frequency proximity. These emitters can  include broadcast, communications, and navigation transmitters, as well as power  tools, fluorescent lights, cooling fans, and (old) automobile ignitions, which typically  generate impulsive noise. * RFI can arrive via a direct path or multipath and includes  scattering from terrain or sea surfaces, also called clutter. 
 Accurate  calibration of the gonio scale was arranged to coincide  with actual aerial array position, but, of course, it will  be seen that such an arrangement is equivalent only to  the normal elementary ‘frame aerial? DF, and gives  indication of line of shoot only, without showing if it  is to the back or front. This was not at first a disadvan-  tage, for radar was visualized only as a warning system  for detecting aircraft approaching from over the coast.  But when radar became miniaturized, and centimetric  equipment was fitted to aircraft, some more easily  decipherable map was essential than that given. 
 The variable component of the radar-target distance is then  ∆Rtgt(t) = d sin (2p   fvibt) (17.41) where fvib is the vibration frequency. Let the normalized complex echo corresponding to a stationary pixel be ej f td2π,  where fd is the doppler frequency characteristic of the pixel. (We assume low fractional  bandwidth, in which case this is equivalent to the doppler frequency corresponding   to the center frequency of the transmitted bandwidth; see Section 8.1.5 of Sullivan1). 
 E. Ziemer, T. Lewis, and L. 
 Figure 8.9  MTI with Delay -Line Canceller.   The output of the subtractor can be utilized for the brightness modulation of a PPI scope  (Plane Position Indicator).  The delay time is equal to the period T of the signal. 
 Practical deviceshaveisolation oftheorderof20to50dB.Turnstile junc­ tions7achieveisolations ashighas40to60dB. Theuseoforthogonal polarizations fortransmitting andreceiving islimitedtoshort­ rangeradarsbecauseoftherelatively smallamountofisolation thatcanbeobtained.8 Animportant factorwhichlimitstheuseofisolation deviceswithacommon antenna is thereflections produced inthetransmission linebytheantenna. Theantenna canneverbe perfectly matched tofreespace,andtherewillalwaysbesometransmitted signalreflected back towardthereceiver. 
  
 LOOKING AIRBORNE RADAR  3,!2 = AND #ANADA USING A MODIFIED 8 
 Fried. W. R.: New Developments in Radar and Radio Sensors for Aircraft Navigation, IEEE Trans.,  vol. 
 Radar: "Digital Signal Processing," IEEE Press, New York, 1972.  12. White, W. 
 MOTION CASE.   05,3% $/00,%2 2!$!2   {°Ç (OWEVER  SOME PULSE DOPPLER RADARS EMPLOY A 02& THAT IS UNAMBIGUOUS IN VELOC 
 J. Brain, “Radar performance test Methods—final report,” Research Project  RP544, UK Maritime and Coastguard Agency, Southampton, 2005. 37. 
 Although these are normally centered on the ship (at the CCRP), they  can also be offset to any position. Readouts relative to own ship’s heading or true north  can be set. The EBL origin can also be set such that it follows own-ship movement or is  ch22.indd   20 12/17/07   3:02:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The band from 4.2 to 4.4 GHz is reserved for radio altimeters, altlloligh they have in the  past operated at UHF. The transmitter power is relatively low and can be obtained from a CW  magnetron, a backward-wave oscillator, or a reflex klystron, but these have been replaced by  the solid state transmitter.  The altimeter can employ a simple homodyne7' receiver, but for better sensitivity and  stability the superheterodyne is to be prefered whenever its more complex construction can  be tolerated. 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 individual aperture would be in phase. As  the target moves off axis in either direc - tion, there is a change in relative phase. 
 As mentioned earlier, when  the digital phase samples include the carrier components, the I and Q components are  centered on this carrier frequency and the low-pass filter can be replaced with a band - pass filter centered on the IF carrier. When a linear-FM waveform is desired, the phase samples follow a quadratic pat - tern and can be generated by two cascaded digital integrators. The input digital com - mand to the first integrator defines this quadratic phase function. 
 56, pp. 18 1 1 - 18 17.  November, 1968. 
 119-141, September, 1954.  34. Middleton, D., and D. 
 § ©¨ ¨¨¨¨¨¶%% %% %% %%HV HV HV HV  2E   )M  ¸ ¸· ·····    WHEN THE WAVE IS COMPLETELY POLARIZED    )    1   5   6    BUT WHEN IT IS PARTIALLY POLARIZED   )    1   5   6    )N FACT  WHEN THE WAVE IS COMPLETELY UNPOLARIZED SUNLIGHT  FOR EXAMPLE    %V AND %H  ARE UNCORRELATED  SO 5 AND 6 ARE BOTH ZERO 7AVES OF THIS TYPE  ARE USED IN POLARIMETRIC  RADAR HOWEVER  TO  SEE HOW THE SCATTER 
 Skolnik21(pp. 520–521) points out that, since for stripmap SAR the crossrange  resolution dcr ≅ D/2 (Eq. 17.4), Eq. 
 $%&).% #!0!#)4/2  "/44/- 0,!4% -%4!, 0,!3-! %4#(  4!.4!,5- .)42)$% 0,!3-! %4#(  3),)#/. .)42)$% 2ESISTOR #APACITOR &%4$%&).% !)2"2)$'% 0),,/73 0!44%2. !.$ $%0/3)4  4()#+ -%4!,  2%-/6% !)2  "2)$'% 0),,/73  !.$ $/ &).!, &2/.4 3)$% $# 4%34 -/5.4 7!&%2 /. #!22)%2  '2).$%4#( 4/  MM  -!3+ !.$ %4#( 6)!3 0,!4% 50 6)!3  $%&).% '2)$  $)#% !.$ $)3-/5.4 $%&).% !)2"2)$'%3   4()#+ -%4!,  %,%#42)#!, 4%34 7!8 3!00()2% MM$%0/3)4 3I . 0!33)6!4)/.   &/,,/7%$ "9 4A. 4(). &),-2%3)34/23                    MM.)42)$% 4!.4!,5- 4()#+ -%4!, #!0 "/44/-#!0 "/44/- '!4% -%4!, 'A!S .)42)$% 4!.4!,5-0(%-4 %0)4!8)!, ,!9%23 'A!S 35"342!4% /(-)# -%4!,.   3/,)$ 
 The result is that the doppler spec - trum for a side-looking radar like that shown in the example is not rectangular but  rather has the shape of the antenna along-track pattern. Thus, if the antenna pattern in  the along-track direction is G = G(b), with b  the angle off the beam center, we can  express b  in terms of the doppler frequency fd as  b = fd l/2v  and the spectrum is  W fP r RGf vdt x d( )( )=  λ σ πλ3 0 3 32 2 4 2  where rx is the horizontal resolution in the range direction. Of course, the half-power  beamwidth may be used as an approximation, resulting in the bandwidth given by  Eq. 
 In  general, the continuous tracking radar and the TWS radar employ different types of  equipment.  The antenna beam in the continuous tracking radar is positioned in angle by a servomech-  anism actuated by an error signal. The various methods for generating the error signal may  be classified as seqttential lobing, conical scan, and simltltnrieolts lohirly or monnp[rlse. 
 35. (ilegg. K. 
 RATE REQUIREMENTS CONFRONTING PLANETARY OR LUNAR MISSIONS !LTERNATIVELY  THE INTERVALS BETWEEN BURSTS MAY BE USED TO ILLUMINATE SEVERAL DIFFERENT RANGE SWATHS  THUS EXPANDING THE AREA THAT MAY BE IMAGED UNAMBIGUOUSLY 4HIS IS THE PRINCIPLE BEHIND THE 3CAN3!2 MODE !MBIGUITY 3PACE 4RADE 
 Although they add complexity, cost, and possibly weight to the antenna, reduction  of main-beam width and control of coverage and scan are valuable and worthwhile  ECCM features of all radars. If an air defense radar operates in a severe ECM environment, the detection range  can be degraded because of jamming entering the sidelobes. On transmit, the energy  radiated into spatial regions outside of the main beam is subject to being received  by enemy RWRs or ARMs. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar.  CIVIL MARINE RADAR  22.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 FIGURE 22.6  A ship’s radar display ( Courtesy of Northrop Grumman Sperry Marine BV ) ch22.indd   21 12/17/07   3:02:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 18.33  18.7 Sources of Error  .....................................................  18.33  18.8 Target-Caused Errors (Target Noise)  .....................  18.34  Amplitude Noise  ................................................ 
 It includes thatportionoftheradarreceiver fromtheoutputoftheIFamplifier totheinputof theindicator ordataprocessor. Weshallnotbeconcerned abouttheproblem ofamplification, although itisanimportant aspectofreceiverdesign.Instead, weshallbemoreinterested inthe effectofthedetector onthedesired signal andthenoise. Oneformofdetector istheenvelope detector, whichrecognizes thepresence ofthesignal onthebasisoftheamplitude ofthecarrierenvelope. 
 When fi = lXOO, the  doppler frequency is zero; therefore moving targets cannot be discriminated on the basis of  0 20 40 60 80 100 120 140 160 180  Scattering angle P, deg  Figure 14.13 Bistatic cross section a, of a sphere as a function of the scatter~ng angle 0 and two valucb of  ku = 2na/A, where a is the sphere radius and ). is the wavelength Solid curves are for the E plane (fl  measured in the plane of the E vector); dashed curves are for the H plane (fl measured in the plane ofthe H  vector, perpendicular to the E vector) 6s.69  558INTRODUCTION TORADAR SYSTEMS targetdimension.60Ifabistaticradarcanbedesigned totakeadvantage ofthelargeforward­ scattercrosssection,asignificant improvement indetection capability canbehad,orforthe samedetection capability asaradarwithP=f180°,lesspowerneedberadiated. However. 
 It should be noted that the IF  bandwidth of the receiver in FMCW and SFCW systems can be made relatively small  whereas the sampling receiver in the time-domain receiver has a bandwidth of many  GHz and hence a poor noise performance. The main potential advantage of a stepped frequency or FMCW GPR is its abil - ity to adjust the range of frequencies of operation to suit the material and targets and  electromagnetic environment under investigation if the antenna has an adequate pass - band of frequencies. It can radiate a higher mean power level per spectral line than  the time-domain radar, and its ability to integrate the received signal level improves  the system sensitivity. 
 For ‘(long wave” radars (wavelengths of50cmand greater) wave guide isnever used because ofitsrelatively enormous size. 11.4. Resonant Cavities.-If both ends ofawaveguide are closed byashort-circuiting plate, and energy isintroduced byaprobe sosmall that itdoes not appreciably change the properties ofthe enclosure, the amplitude ofthe standing-wave pattern inthe waveguide will show a sharp maximum when the frequency issuch that the length ofthe enclosure isanintegral number ofhalf guide-wavelengths. 
   PP n  3EPTEMBER   ! , -C'UFFIN  h! BRIEF ASSESSMENT OF ADAPTIVE ANTENNAS WITH EMPHASIS ON AIRBORNE RADAR v  'ENERAL %LECTRIC #OMPANY  !IRCRAFT %QUIPMENT $IVISION  !UGUST   " 7IDROW AND 3 $ 3TEARNS  !DAPTIVE  3IGNAL  0ROCESSING  .EW *ERSEY 0RENTICE 
 on Radar Meteorol.  AMS, 1991, pp. J7–J9. 
 NAL STRENGTH  WHICH IS THE VECTOR SUM OF THE SIGNAL STRENGTHS OF THE DIRECT AND REFLECTED WAVE  MAY VARY UP TO  D" ABOVE AND  D" OR MORE BELOW THE FREE 
               &IGURE  SHOWS THE PERFORMANCE INDICATED WITH THESE ASSUMPTIONS FOR ALL RANGES  ! PATH FACTOR ENHANCEMENT OF  D" HAS BEEN CHOSEN AS A REPRESENTATIVE VALUE OF CONSTRUC 
 ch24.indd   11 12/19/07   6:00:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 At the accuracy required of a space-based oceanographic altimeter,  the deceptively simple proportionality of range to delay-time must take into account  the small but significant retardation of the radar’s microwaves as they propagate. The  cm-level SSH accuracy required of these instruments is much smaller than the ranging  errors introduced by delays through the ionosphere and the atmosphere. The delays  imposed by the ionosphere are a function of frequency. 
 983-988, August 1965. 42. Cost, S. 
 Early in 1934, a 60-MHz CW  wave-interference radar was demonstrated by NRL.  The early CW wave-interference radars were useful only for detecting the presence of the  target. The problem of extracting target-position information from such radars was a difficult  one and could not be readily solved with the techniques existing at that time. 
 SENSITIVE GRATING IS ETCHED ON THE CRYSTAL SURFACE TO REFLECT A PORTION OF THE SURFACE 
 1 182- 1 190, August, 197 1.  16. Torrey, H. 
 The radar cross section a of targets at HF is often different than at microwaves. Since  many targets have dimensions comparable to the HF wavelength, or component structures  with dimensions comparable to the wavelength, the target is often in the resonance region  where the radar cross sections are generally larger than at microwaves. At the lower HF  frequencies where the wavelength is large compared to the target dimensions, the cross section  will be in the Rayleigh region where rr decreases rapidly with decreasing frequency. 
 M. Siegcl, and H. Weil: Forward Scattering by Coated Objects Illuminated l>y Sllol-t  Wavelength Radar, Pror.. 
  ALTIMETERS USED CONVENTIONAL PULSE 
 68. McCarthy, J., and R. Serafin: The Microburst: Hazard to Aviation, Weatherwise, vol. 
 LECTED USING THE SAME EIGHT DIRECTIONAL BEAMS AS THE BACKSCATTER SOUNDER 7HILE THERE ARE A FEW SIGNIFICANT GAPS IN THESE TIME SERIES  THEY SPAN TWO SOLAR  CYCLES FURTHER  INTEGRITY HAS BEEN MAINTAINED BY EXTENSIVE VETTING BEFORE ENTERING NEW DATA INTO THE DATABASE 4HE UNIQUE ADVANTAGE OF THIS DATABASE IS THAT THE NOISE AND PROPAGATION DATA ARE RECORDED UNDER IDENTICAL IONOSPHERIC CONDITIONS  WHEREAS COM 
 G. Amin, and G. J. 
 The function g(t) to be analyzed is that in which each radiation consists of a short, linearly frequency-modulated signal. An expression for g(t) in this case is *(/) = */a'2 (21.34) The use of Eq. (21.34) in Eq. 
 In a military application, when a  system needs to be reset in order to fix a problem, the system needs to come back to  full operation in a very short period of time. These multiprocessor systems typically  take a long time to reboot from a central program store and, hence, have difficulty  meeting reset requirements. Developing techniques to address these deficiencies is an  active area of research. 
 (b) The air is a perfect gas, obeying the Laws of Charles and Boyle. (c) Gravity is constant at all altitudes. (d) The temperature of the isothermal atmosphere is −55º C. 
 BY 
 ‘Itwill beobserved that theresponse atsmall speeds isproportional tothespeed v.Itcanbewritten asfollows: Response Llax. responsez~jdT==Z, VI(20) where VIisthe first blind speed. Asanexample, consider asetwith A=9.2cmand~, =2000 pps. 
 The  expanded metal mesh made from aluminum is a popular form. A nonsolid surface such as a  mesh offers low wind resistance, light weig~t, low cost, ease of fabrication and assembly, and  the ability t~,conform to variously shaped reflector surfaces.14 However, a nonsolid surface  -----+  I  I  I  I --y-----+  \ I  \ I  \ I  \ I ------,,-----+  ----~Feed Figure 7.10 Parabolic reflector with offset feed. 240 INTRODUCTION TO RADAR SYSTEMS  may permit energy to leak through, with the result that the backlobe will increase and the  antenna gain decrease. 
 Radar is an active device in that it carries its own transmitter and does not depend on ambient radiation, as do most optical and infrared sensors. Radar can detect relatively small targets at near or far distances and can measure their range with precision in all weather, which is its chief advantage when compared with other sensors. The principle of radar has been applied from frequencies of a few megahertz . 
 Hardy, T. G. Konrad, W. 
 Withascanning phased-array antenna, however, the radiation pattern,whichisafanbeamatbroadside, becomes aconicalbeamwhenscanned ofT broadside. Thiscancauseanerrorintheelevation measurement ifthetargetisoffthecenterof thebeam.Forthisreason,heightfinderswhichuseelectronic scanusuallyradiatepencil beamsratherthanbroadfanbeams. V-beam radar.Thisradar g~nerates twofanbeams:oneverticalandth~otherslantedatsome angletothevertical(perhaps at30to45°).Thetimeseparation between theechoes receiv~d in theverticalandslantbeamsisameasure ofthetargetheight.Ashort tim~-separation signifies lowaltitude, whilelongerseparations occurwithhighaltitudetargets.Twoseparate retlectors maybeusedtogenerate thetwoJanbeams,30 thetworeflectors mightbebacktoback,asingle retlector withtwofeedscan:beusedf~hJ60r thetwobeamscanbegenerated withasingle phasedarrayantenna.\ The,V-beam :radar Iisasatisfactory method forobtaining three­ coordinate targetinformation ifthenumberoftargetsisnotexcessive. 
 K., and W. B. Goggins: Efficient, Closed-Form Computation of Airborne Pulse Doppler Clutter, Proc. 
 WARFARE APPLICATION FOR THE FIRE CONTROL OF 'ATLING GUNS "OTH  SYSTEMS TAKE FULL ADVANTAGE OF THE TWO BANDS TO PROVIDE PRECISION TRACKING IN MULTIPATH AND ELECTRONIC 
 The first echoes at 200 MHz were  received July 22, 1936, less than three months after the start of the project. This radar was also  the first to employ a duplexing system with a common antenna for both transmitting and  receiving. The range was only 10 to 12 miles. 
 MONTH INTERVALS )N THIS CASE  MODULE -4"& NEED ONLY BE   H TO PROVIDE  CONFIDENCE THAT THE TRANSMITTER  &)'52%   #OMMON SOLID 
 Cooling the device will therefore  improve the noise figure. 2 1  The tunnel-diode amplifier has been considered in the past as a low-noise front-end, with  noise figures from 4 to 7 dB over the range 2 to 25 GHz.10 It has been supplanted by the  improvements made in the transistor amplifier. The traveling-wave-tube amplifier has also  been considered as a low-noise front-end, but it has been overtaken by other devices. 
 18.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 JianBing-5.  Known alternatively as Remote Sensing Satellite-1, Jianbing- 5 is China’s first synthetic aperture radar mission. The spacecraft mass is 2700 kg,  launched into a sun-synchronous orbit at ∼600 km altitude. 
 Yeomans Raytheon Company 6.1 THE CONFIGURATION   OF A RADAR RECEIVER The function of a radar receiver is to amplify, filter, downconvert, and digitize the  echoes of the radar transmission in a manner that will provide the maximum discrimi - nation between desired echo signals and undesired interference. The interference com - prises not only the self noise generated in the radar receiver but also the energy received  from galactic sources, neighboring radars and communication equipment, and possibly  jammers. The portion of the radar’s own radiated energy that is scattered by undesired  targets (such as rain, snow, birds, insects, atmospheric perturbations, and chaff) may  also be classified as interference and is commonly categorized as clutter. 
 12. W. Yirong, Z. 
 H2. +2 and wehave torequire L Gcos@d@ dtl=1.Since Gisvery47ro_; 1This expression will,berecognized asthediffraction pattern ofarectangular aperture. SeeVol. 
 High-resolution results in a probability density function that is non-Rayleigh for both land  and sea clutter, but the spatial distribution of land clutter provides interclutter visibility that  permits the detection of targets that lie outside the separated clutter patches of large a'. The  non-Rayieigh pdf, however, limits !he utility of the log-FTC receiver and frequency agility in  land clutter.  There are two clutter reduction techniques, peculiar to land clutter, which will be men-  tioned briefly in this section. 
 H TIME BLOCKS ,UCAS AND (ARPER HAVE  PROVIDED A NUMERICAL REPRESENTATION OF ##)2 2EPORT  
 Applications range from ultrahigh frequency  (UHF) for surveillance to X band and above for  airborne systems. A typical module is shown in simple sche - matic in Figure 13.36. It consists of a transmitter  amplifier chain, a preamplifier for receiving, a  shared phase shifter with driver, and circulators  and/or switches to separate the transmit and  receive paths (the gain around the loop must  be less than unity to avoid oscillations). 
 Theimprovement factorcanbewrittenas I=(SoIC0)=(So)XCj=(So) xCA (4.20) Si/CjaveSjaveCoSjave whereSolCo=output signal-to-clutter ratio,Si/Ci=inputsignal-to-clutter ratio,and CA=clutterattentuation. Theaverage istakenoveralltargetdoppler frequencies ofinterest. Forasingle-delay-line canceler, theclutterattentuation is $:Wendf CA=s:W(f)\H(f)12~1 (4.21) whereH(f)isthefrequency response function ofthecanceler. 
 The range-tracking loop is closed by using the range-error-detector output to repo - sition range gates and correct range readout. One technique uses a high-speed digital  counter driven by a stable oscillator. The counter is reset to zero at the time of the  transmit pulse. 
 Barnett: On Some Direct Evidence for Downward Atmospheric  Renee! ion of Fleet ric Rays. Prnc. Ro J'. 
 02& WAVEFORM  (OWEVER  LINEAR 
 However, radar can be designed to see through those conditions  impervious to normal human vision, such as darkness, haze, fog, rairi, and snow. In addition,  radar has the advantage of being able to measure the distance or range to the object. This is  probably its most important attribute. 
 Figure 15.24 shows the effect of feedback on /. These curves are calculated for a (sin U)/U antenna pattern terminated at the first nulls. The no-feedback curves shown here are almost indistinguishable from the theoretical curves derived for a RESPONSE (dB) 14.4 HITS PERBEAMWIOTH Z PLANEDUAL-DELAYCANCELER TWO ZEROS AT ORIGIN POLES POSITIONEDAS SHOWN DISTANCE FROM CENTER OF UNIT ClRCLE = yK7~~ DISTANCE FROM ORIGIN V^-K2 K1-HK20= ARC COS ' Z2vH<7 . 
 A control electrode20'21 usually consists of a segment of the cathode structure in the drift region, as shown in Fig. 4.6. The control electrode is pulsed positiveANODE ANDSLOW-WAVECIRCUIT"COLD"CATHODE RFOUT DRIFTREGIONCONTROLELECTRODE(IF USED) . 
 The doppler shift can be expressed in terms of the velocity vector v as dRt R1-^. = _ 2k—^- = - 2k v - — = - 2kv cos (V5R,-) (12.10)dt RJ Hence the total field is given by E=YA, exp j cocr - [2k v • -4* - IkR10 (12.11) i ILo*' J ' where A1- is the field amplitude of the /th scatterer and RiQ is the range at time zero. The only reason the scalar product is different for different scatterers is the different angle between the velocity vector and the direction to the scatterer. 
 POLARIZED 6( TRACES ARE SHOWN BECAUSE THE (( AND (6 MEASUREMENTS CLOSELY TRACK THE 66 AND 6( DATA 4HE MEASURED DATA ARE THE RAPIDLY VARYING TRACES AND WERE FITTED STATISTICALLY TO THE SMOOTHLY VARYING TRACES REPRESENTING THE EXACT SOLUTION OF THE TWO 
 For example, using a frame of 224×224 to do random crop in a picture of 256 ×256. It not only increases the data, but it also retains the most information of the data. However, not all traditional ways of data processing can be helpful when dealing with SAR images. 
 (11) Then the dictionary matrix can be obtained as: Ai=[α(f1,θ1),···,α(f1,θM),α(f2,θ1),···,α(f2,θM),···,α(fN,θ1),···,α(fN,θM)] (12) Therefore, the projection relationship between the scene and signal in ichannel is obtained. The radar signal model in the interferometric channel is represented as follows: s=/bracketleftBigg s1r s2r/bracketrightBigg =Ag+e=/bracketleftBigg A10 0A2/bracketrightBigg/bracketleftBigg g1 g2/bracketrightBigg +/bracketleftBigg e1 e2/bracketrightBigg , (13) where, scorresponds with the echo signal in the interferometric channel, Acorresponds with the dictionary matrix in the interferometric channel, gcorresponds with the backscatter coefﬁcient in each interferometric channel, and ecorresponds with the additive noise in each interferometric channel. It should be noted that the dictionary matrix corresponding with each interferometric channel may be the same. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 Phase-Shifter Quantization Lobes. 
 The mixing operation results in a time expansion of a = (B1 + B2)/Bl ; but the range-  resolution possible is that of a signal of bandwidth B1 + B2, using processing circuitry of  bandwidth B1.  Compatibility with other processing. Pulse-compression systems are sometimes used in con-  junction with MTI radar.39 The increased range resolution afforded by pulse compression  provides an increased target-to-clutter echo, as does the MTI processing. 
 In the North Sea the mean duct thickness is  about 6 m while in tropical regions it is of the order 10 to 15 m.34 In the North Atlantic at  Weather Ship D (44"N, 4 i "W) the median value of duct thickness (half the ducts have thickness  of lesser value) is 10 min the summer and 30 min the winter. 35 In the area offshore of San Diego,  the medium value of the duct thickness as calculated from 5 years of meteorological data is  6 m. and a similar calculation for the Mediterranean Sea is 10 m.36 Measurements made in the  Atlantic tradcwind area off of Antigua showed ducts averaging 6 to 15 m in height.37 The . 
 TION OF INITIAL WAVE MOTION ! PORTION OF ENERGY IS ALSO REFLECTED BACKWARD TOWARD THE TRANSMITTER 4HIS BACKWARD REFLECTED ENERGY IS ALSO RECEIVED BY THE RADAR AND MAY INTER 
 It is noted that when the jammer DoA is around 80°, the SINR decreases; this  is because of the grating lobe. The maximum value of SINR is 10.79 dB = 10log1012,  because there are no tapering losses.FIGURE 24.11  SINR versus the jammer DoA (JDoA)0 20 40 60 8 0 100−40−20020 JDoA (°)SINRout (dB)Adaptivity at subarr ay level No adaptivity , raised cosine taper Pattern with raised cosine FIGURE 24.12  SINR versus the JDoA for a regular sub-array architecture  and no tapering0 20 40 60 80 100−40−30−20−1001020 JDoA (°)SINRout (dB) ch24.indd   29 12/19/07   6:00:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 TABLE 22.6 Characteristics of Seasat, SIR-A, SIR-B, and SIR-C Antennas SIR-C SIR-B SIR-A Seasat 1275 and 5300 MHz > 20 MHz 37.0 dB (L band); 43.0 dB (C band) Horizontal linear and vertical linear Adjustable through amplitude and phase, 0.99° L band; 0.24° C band Tilted to 35°, then ±25° elec- tronically steered 12.06 x 4.2 m 4.1 x 4.2m 900kg Graphite-epoxy 2D truss Two folds (motor-driven) 864 (L band); 5184 (C band) 9 Microstrip, coaxial, waveguide 17.76831282 MHz 16MHz 33.0 dB Horizontal linear 6.2° 1.1° 15 to 60° (mechanical steering) 10.74 x 2.16 m 4.1 x 2.16m 306kg Rigid aluminum 2D and 3D truss Two folds (motor-driven) 1024 8 Microstrip, coaxial 13.19061278 MHz 8MHz 33.6 dB Horizontal linear 6.2° 1.4° 47° 9.4 x 2.16m 181kg Rigid aluminum 3D truss Fixed 896 7 Microstrip, coaxial 8.91451275 MHz 22MHz 34.9 dB Horizontal linear 6.2° 1.1° 20.5° 10.74 x 2.16m 1.34 x 2.16m 103kg Graphite-epoxy 3D truss Multifold (spring-loaded) 1024 8 Microstrip, coaxial and sus- pended substrate 4.44Frequency Bandwidth (1.5:1 VSWR) Gain Polarization Bcamwidths H plane E plane Beam-pointing angle Size (deployed) Size (folded) Weight Support structure Fold mechanisms Number of radiating elements Number of panels Feed system WIA, kg/m2 . ically steerable. The SIR-C antenna is electronically steerable and dual- frequency. 
 KNOWN  SUCH FREEBOARD MEASUREMENTS CAN BE INVERTED TO ESTIMATE ICE THICKNESS  £n°{Ê *  
 I.  1,og-FTC receiver. A receiver with a logarithmic input-output cllaractcristic followed by a  high-pass filter (fast-time-constant, or FTC, circuit), will provide a constant false-alarm rate  (CFAR) at the output when the input clutter or noise is described by the Rayleigh probability  density function. 
 J., and F. J. Paul, "Aerospace Ranges: Instrumentation," D. 
 Any use is subject to the Terms of Use as given at the website. Radar Receivers. 6.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 in complex form in Eq. 6.26. 
 Another property of the radiation patterns illustrated by 'Table 7.1 is that the antennas  with the lowest sidelobes (adjacent to the main beam) are those with aperture distributions in  wliicli the amplitude tapers to a sniall value at the edges. The greater the amplitude taper, tlie  lower tlic sidelobe lcvcl 1,111 tl~c less tllc rclative gait1 and tlie broader the beainwidtli. Thus low  sidelobes and good aperture eficiency run counter to one another. 
 Barton. D. K., and W. 
 A search  radar, when used for this purpose, it called an acquistion radar. The acquisition radar desig­ nates targets to the tracking radar by providing the coordinates where the targets are to be  found. The tracking radar acquires a target by performing a limited search in the area of the  designated target coordinates. 
 NAL AREAS ON EACH FACE OF THE CORNER RECEIVING WAVES REFLECTED BY THE OTHER FACES AND FROM WHICH THE FINAL REFLECTION IS BACK TOWARD THE SOURCE 4HE EFFECTIVE AREA IS DETER 
 (2.27)  where a = ratio of signal (sine-wave) amplitude to rms noise voltage and Io(x) = modified  Bessel function of zero order. The detection process is equivalent tc determining which of the  two density functions [Eq. (10.33) or (10.34)] more closely describes the output of the receiver. 
 718. Itisessential forthepilot toknow which ofthebeacon responses is that ofhisown plane. This isaccomplished byhaving arotating radial line, centered atthe radar station (which appears inthe center ofthe picture), form part ofthe display information transmitted from the ground station, This line isnormally invisible, butthetelevision receiver iscontrolled byasignal from thetransponder insuch away that theline. 
 F. T.: Radar Response to Vegetation, IEEE Trans .• vol. AP-23. 
 THE 
 Knott1 © American  Institute of Aeronautics and Astronautics, 1992 ) ch14.indd   2 12/17/07   2:46:43 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 
 One important operation of this type is that of focusing. A physical linear array can be focused to a specific range. There will then be a depth of focus surrounding this range. 
 EXPLOITED ADVANTAGE OF BROAD BEAMS IN ELEVATION IS THE ABILITY TO ILLUMINATE AN EXTENDED RANGE DEPTH WHEN CONDITIONS PERMIT  PROVIDING CLUTTER MAPS OUTSIDE THE RANGE BAND OF IMMEDIATE INTEREST FOR TARGET DETECTI ON THESE CAN BE USED TO  SCHEDULE SUBSEQUENT SURVEILLANCE TASKS Óä°ÇÊ , ,Ê ,"--Ê- 
 Con( Proc .. -frrmwut. Electro11ic.s  (Dayton. 
 Reduction of Spurious Outputs.  RF tube spurious outputs may be grouped into  three kinds: harmonics, adjacent-band, and in-band. All RF tubes produce some harmonic output. 
 3.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 to the antenna elements. Temporal adaptive array  processing combines an array of  signals received at the same spatial location (e.g., the output of a reflector antenna)  that are sampled at different instances of time, such as several interpulse periods for  an adaptive MTI. Space-time adaptive array processing combines a two-dimensional  array of signals sampled at different instances of time and at different spatial locations. 
 5.8. F-m Range-measuring System.—The next system to be described isonethat illustrates thef-m technique ofrange measurement. The specific problem isthat ofaradio altimeter. 
 For two-angle tracking with a mechanical-type antenna there are typically separate axes of rotation for azimuth and elevation and sepa- rate servosystems to move the antenna about each axis. A conventional servosystem is composed of amplifiers, filters, and a motor that moves the an- tenna in a direction to maintain the antenna axis on the target. Range tracking is accomplished by a similar function to maintain range gates centered on the received-echo pulses. 
 IEEEPubl.75CHO998-5 EASCON. rr.107-A10107-0.1975. 32.Appleton. 
 22. 68. Technology Service Corp., “Adaptar space-time processing in airborne radars,” TSC-PD-061-2,  February 24, 1971, unclassified report. 
 FIELD PATTERNS OF ALL  SPECTRAL COMPONENTS 4HIS ANALYSIS HAS BEEN PERFORMED   AND  IT IS APPARENT THAT THE OVERALL ANTENNA GAIN OF THE PULSE WILL BE LESS THAN THAT OF A SINGLE SPECTRAL COMPONENT THAT HAS MAXIMUM GAIN IN THE DESIRED DIRECTION !S WITH THE #7 SITUATION  THE GREATEST LOSS OCCURS AT THE MAXIMUM SCAN ANGLE  WHICH IS ASSUMED TO BE n &OR THIS SITUATION  THE CRITERION CHOSEN IS TO ALLOW A SPECTRUM THAT LOSES  D" OF  ENERGY ON TARGET DUE TO FREQUENCY 
 Itisusually possible toallow some ofthe pulses to take part inthetransmission ofmore than one piece ofdata. Often the modulator pulse itself isused aspart ofthis timing system. When the subcarrier method isadopted, itiscustomary touse con- tinuous waves rather than pulses, partly forreasons ofsimplicity and partly because ofsmaller bandwidth requirements. 
 The solid trace is the calculated RCS of water droplets for comparison. (Copyright, 1985 IEEE.14)LOCUSTS MOTHS HONEYBEES LADYBUGS MOSQUITOESAPHIDSRADAR CROSSSECTION (cm2) Insect Blue-winged locust Armyworm moth Alfalfa caterpillar butterfly Honeybee worker California harvester ant Range crane fly Green bottle fly Twelve-spotted cucumber beetle Convergent lady beetle Spider (unidentified)Length, mm 20 14 14 13 13 13 9 8 5 5Width, mm 4 4 1.5 6 6 1 3 4 3 3.5Broadside RCS, dBsm - 30 - 39 - 42 -40 - 54 -45 -46 -49 - 57 - 50End-on RCS, dBsm - 40 - 49 - 57 -45 - 57 - 57 - 50 - 53 -60 - 52 . Examples of the RCS of aircraft are shown in Figs. 
 IMAGE SYMMETRY !LSO NOTE THAT THE AREA OF EVERY BISTATIC OVAL IS ALWAYS LESS THAN THE MONOSTATIC CIRCLE 4HE EXPRESSIONS IN 4ABLE  CAN ALSO BE USED TO ASSESS FIRST 
   NO   PP n   -ARCH   7 & 'ABRIEL  h!DAPTIVE PROCESSING ARRAY SYSTEMS v  0ROC OF THE )%%%  VOL   NO   PP n   *ANUARY   3 0 !PPLEBAUM  h!DAPTIVE ARRAYS v  )%%% 4RANS !NTENNAS AND 0ROPAGATION  VOL !0 
 The clutter can be calculated as in a pulse radar, then folded in range as a function of the PRF. Ground Clutter in a Moving Radar. When the radar is moving with a velocity VR, the clutter is spread over the frequency domain as illustrated in Fig. 
 At low sea-state and wind it is possible to image  an oil spill of less than 400 liters during the period of spillage. 68  13.4 DETECTION OF TARGETS IN SEA CLUTTER  The ability of a radar to detect targets on or above the sea can be limited by sea clutter as well  as by receiver noise. The magnitude and extent of the sea clutter seen by the radar will depend  not only on the sea state and wind, but on the radar height. 
  AIRPORT SURVEILLANCE RADAR )N THE MID 
 Multilook processing is commonly used in SAR image TABLE 24.4  Simulation Results With SOJ and A-SOJ TARGET NO.LOST TARGETS Ts (s) Tave (s) PM (W)POS ERR (m)VEL ERR (m/s) 1 1 1.944 0.5144 10–3   6.6179 127.5 71.09 5 1 0.6888 1.452 10–368.411 103 66.78 6 4 1.118 0.8944 10–315.11   80.49 59.59 TABLE 24.5  Simulation Results With RGPO and Without A-RGPO TARGET NO.LOST TARGETS Ts (s) Tave (s) PM (W)POS ERR (m)VEL ERR (m/s) 1 48 1.963 0.5095 10–3 5.044 120.5 66.6 5 50 6 50 TABLE 24.6  Simulation Results With RGPO and A-RGPO TARGET NO.LOST TARGETS Ts (s) Tave (s) PM (W)POS ERR (m)VEL ERR (m/s) 1 0 1.889 0.5295 10–3   6.6179 127.5 71.09 5 1 0.7045 1.419 10–368.411 103 66.78 6 0 1.156 0.8651 10–315.586 124.9 80.26 ch24.indd   48 12/19/07   6:01:11 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 The main limitations of the proposed algorithm depend on its need for the presence of a strong point scatterer in the imaged zone. This limitation is payed back by its simplicity and the lack of need for the ancillary parameters ﬁle in the focusing procedure, aspect that simpliﬁes both the processing and the development of simple and cheap SAR systems to be used in local monitoring also with the recourse to simple aerial unmanned vehicles such as drones. The focused image is obtained, at the state of the art, by SVD analysis. 
 49–56, February 1999. 158. S. 
 SEC. 15.12] DESIGN OBJECTIVES AND LIMITATIONS 611 azimuth asradar signals, since thebeacon istriggered only over thenar- rowbeam oftheradar antenna used fortransmitting thebeacon challenge. The beacon receiver has aseparate local oscillator and ani-fband- width of10Me/see, toallow fordifferences infrequency among beacon transmitters inthe various aircraft. 
 V,actsasalimiting 2U 4+1t++.!lfnIIv~~c-nl----—Tl—T— ---&JLL_____JLL__ LS6C~&&Lllu_ ----~ ~r H~----–-..J.!J- i- FIG. 17.3.—Interference blanker and triple-pulse decoder. amplifier. 
 ING TO RESONANT BACKSCATTER .   (& /6%2 
 The pulse repetition frequencies range from 310 to  360 Hz.  The ARSR-3 contains provision for switching in or out various processing features. A  range-azimuth generator (RAG) permits the selection to be made on the basis of both range  and azimuth. 
   *ULY   2 7 0 +ING AND 4 4 7U   4HE 3CATTERING AND $IFFRACTION OF 7AVES   #AMBRIDGE  -! (ARVARD  5NIVERSITIES 0RESS    2 & 'OODRICH ET AL  h$IFFRACTION AND SCATTERING BY REGULAR BODIES) 4HE SPHERE v 5NIVERSITY OF  -ICHIGAN  $EPT %LECTR %NG 2EPT  
 In general, a module, as shown in Fig. 5.7, consists of a number of identical amplifier stages that are parallel-combined and isolated from one another through the use of microwave combining and isolating techniques. Drive power for this parallel group is obtained from driver or predriver stages, using microwave power dividers. 
 71. Oakley, B. W.: Tracking in an Air Traffic Control Environment, chap. 
 The screw thread and sliding alignment surfaces are external toastainless-steel bellows whose length isthree- quarters the length ofthe delay line. The mean delay is586 ~sec. FIG. 
 (ILL    PP     # ! "ALANIS   !NTENNA 4HEORY !NALYSIS AND $ESIGN   #HAPTERS  AND   .EW 9ORK *OHN 7ILEY  AND 3ONS    ! 7 ,OVE ED    %LECTROMAGNETIC (ORN !NTENNAS  .EW  9ORK )%%% 0RESS    7 #OHEN AND # - 3TEINMETZ  h!MPLITUDE AND PHASE SENSING MONOPULSE SYSTEM PARAMETERS v  -ICROWAVE *  PP n  /CTOBER   $ 2 2HODES  )NTRODUCTION TO -ONOPULSE  .EW 9ORK -C'RAW 
 Furthermore, the use ofsubcarriers and carriers ofhigher order can bemost readily accomplished inasystem which isfrequency- modulated throughout. The above discussion, admittedly rather hypothetical inthe absence ofextended comparative tests, might besummarized asfollows: 1.Amplitude modulation methods seem preferable forthe relaying ofsynchronization pulses (ofwhich there isalways atleast one), the advantage increasing -with the strength oftheinterference. 2.There isprobably little tochoose between AJI and FM with respect tothe video signals. 
 Both of these advanced altimeter modes have been demonstrated with the  D2P airborne altimeter.93 Unlike previous radar altimeter missions, CryoSat will downlink all altimetric  data with essentially no onboard processing. Data from each of the three modes are  ch18.indd   42 12/19/07   5:15:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The actual problem exists in the synthesizing or the piecing together of the various parts of  information.  As the best criterion for this the phase gradient and/or the change of the phase of  the Doppler frequency is  used.  In practice one speaks about the “Doppler history.”  The  change of the phase represents the relative velocity. 
 In a  dipole array, the phase is reversed by reversing every other dipole.  Open-ended waveguides are another popular form of array radiator. They are a natural  extension of the waveguide sections in which the phase shifters are placed. 
 53, pp. 901-920, August, 1965.  30. 
 The primary improvement that is targeted with additional processing is reducing the number of false positives in the image. This goal can be accomplished with the use of the optical ﬂow (OF) method described in Section 2.4. To manage computational complexity, the optical ﬂow algorithm is performed on 256 ×256 pixel image blocks. 
 They produce at the input of a victim system a background which impedes the detection and recognition of useful signals and determination of their parameters. The most common forms of active noise jamming are spot and barrage noises. Spot noise is used when the center frequency and bandwidth of the victim system . 
 IDLY GROWING !LABAMA THUNDERSTORM CELL 4HE DATA DEPICTS A  MS UPDRAFT ORIGINATING IN AN EXTREMELY STRONG  D": RAIN OR HAIL CORE 4HE WIND VECTORS ARE TAKEN FROM COMBINING DATA FROM THREE NEARBY DOP 
 The  pulse repetition frequency cannot always be varied over wide limits since it is primarily  determined by the unambiguous range requirement. In Fig. 4.8, the first blind speed ll1 is  plotted as a function of the maximum unambiguous range (Runamb = c1 /2), with radar  frequency as the parameter. 
 I. Skolnik (ed.), New York:  McGraw-Hill, 1970, pp. 17–56. 
 Botli the rectatigular (az-el) and polar tracking  coordinates may be used.] Wtien the antenna is on target, as in B of Fig. 5.2, the line of sight  to tlic target arid tlie rotation axis coincide, and the conical-scan modulation is zero.  A block diagrar~i of tlie angle-tracking portion of a typical conical-scan tracking radar is  sliowri in Fig. 
 Ifcon- stant-frequency operation isrequired, stabilized magnetrons should be seriously considered. Frequency stabilization has been incorporated into only afew mag- netrons. Agood example isthe2J41, which hasapulse power output of 500 watts at9310 Me/see and apulling figure of1.5Me/see with a tuning range of0.7percent. 
  The indicator should present to the ob server a continuous, easily understandable, graphic  picture of the relative position of radar targets.   All targets produce a diffuse reflection i.e. it is reflected in a wide number of directions. 
 2.Airborne beacons. This combination has proved tobeofgreat usefulness foridentification and forvarious purposes where ground surveillance and control ofairtraffic isdesired. Figure 8.3shows theAN/APhT-19, anairborne 10-cm beacon. 
 However, if reference is made to Eq. (21.24), it is evident that the autocorrelation function ifygg will be periodic if g(t) is periodic. Thus range ambiguities can also occur. 
 TER A  BEHIND THE PHYSICAL APERTURE AND  B  AHEAD OF THE PHYSICAL APER 
 Ocean. Technol. , vol. 
 2007 ,45, 1123–1130. [ CrossRef ] 21. Belcher, D.; Cannon, P . 
 Broadly speaking, there are two ways inwhich energy can bedis- sipated from aradar beam: (1)bydirect absorption ofenergy inthe gases ofthe atmosphere; (2)through absorption orscattering ofenergy bycondensed matter such aswater drops. Allsuch processes lead toan exponential decrease ofintensity with distance from the source, super- imposed on,and eventually dominating, theiu~erse-square dependence.. SEC.215] ATTENUATION OFMICROWAVES 59 The effect istherefore truly anattenuation inthesense inwhich theword isapplied totransmission lines, and isproperly measured indecibels per kilometer. 
 522 INTRODUCTION TO RADAR SYSTEMS  where P, = peak transmitted power  Ae = effective aperture of the real antenna  a = target cross section  n = number of pulses integrated (coherently)  l = wavelength  kT0 = 4 x 10-21 W/Hz  B = receiver bandwidth  Fn = receiver noise figure  R = range  This equation is modified by substituting P, = Pav!T.I~. where Pa"= average power, r = pulse  width~ 1/B, and JP= pulse repetition frequency. Also 11 =.f~t0, where t0 = L.,/l' = time  required to generate the synthetic aperture whose length is given by L., = R)./D, v = velocity of  the vehicle carrying the radar, and D = real-antenna dimension. 
 CHAPTER 17 PULSE DOPPLER RADAR William H. Long David H. Mooney William A. 
 TRACKING ERROR MAY BE SENSED IN MANY WAYS 4HE MOST COMMONLY USED  METHOD IS THE EARLY 
 However, the  environment and the laws of physics often will not permit this. In general, no single  radar can provide a complete surveillance and tracking picture. Radar networking can  be a good solution to this problem and, in some cases, may be more cost effective than  solving the problem through one very high performance radar. 
 (12.4) must be appropriately modified to  account for the actual antenna radiation pattern. Theoretically, the nulls in the lobe structure  are at zero field strength since the direct and reflected signals are assumed to be of equal  amplitude. In practice, ~he nulls are "filled in" and the lobe maxima are reduced because of  nonperfect reflecting surfaces with reflection coefficients less than unity. 
 I>ifTerentiating. with respect to time, the argument of Eq. (1 1.55) the frequency of  ttie doppler-tolerant waveform is found to be 2nf T/( f, T - Bt). 
 POWER 
 TARGET 
 If it contains imagery,  the uplink bandwidth from the missile is relatively large and will have comparatively  lower A/J performance. An adaptive MFAR primary aperture can improve a wider band  missile uplink A/J if the jammer is offset from the target. At the missile end, the missile  antenna can have jammer nulling to improve downlink A/J.43,85 AGC, Calibrate and Self-Test. 
 AP-33, p. 227, February 1985.) 44. A. 
 Ocean. TechnoL, vol. 2, pp. 
 The apertures would normally be tilted  back from the vertical to balance the scan angles. Radiating Elements . The most commonly used radiators for phased arrays are  dipoles, slots, open-ended waveguides (or small horns), and printed-circuit “patches”  (originally called Collings radiator  after their inventor24). 
 The probability margin R is a function of Pe and the separation m of the  radar tracks. The probability margin R was found for m = 0.25s, 0.50s, and 1.00 s by  using simulation techniques, and the results for Pe = 0.01 are shown in Figure 7.43.  FIGURE 7.42  High threshold (solid lines) and middle threshold (dashed lines)  versus number of samples for two different separations ( after G.V . 
 1 dB Compression Point.  The input 1 dB compression point of a receiver  is a measure of the maximum linear signal capability and is defined as the input  power level at which the receiver gain is 1 dB less than the small signal linear gain.  Receiver gain compression can result from compression in amplifiers, mixers, and  other components throughout the receiver chain. 
 Óä°Çn  2!$!2 (!.$"//+   $ ,UCAS  ' 0INSON  AND 2 0ILON  h3OME RESULTS OF 2!$!2# 
 Ivanov, “Venusian impact craters on Magellan images: View from Venera 15/16,” Earth  Moon Planet , vol. 50/51, pp. 159–173, 1990. 
 IEEE. vol. 54. 
 Thus  G G n( ) ( ) q q=∑ en   Impedance Variation of Free Space.  It is of interest to examine the case of a  large continuous aperture that may be considered to be the limiting case of an array  of many very small elements.55 The free-space impedance E/H varies as cos q for  scanning in the E plane and as sec q  for scanning in the H plane. The impedance of  a medium is thus dependent upon the direction of propagation, and the impedance  variation of a scanning aperture is a natural consequence of this dependence. 
 All the products of the form N(H – L)  produce potentially troublesome spurious responses. These frequencies must be fil - tered at RF to prevent their reaching the mixer. If sufficient filtering cannot be applied  prior to the mixing process, spurious products that fall within the operating band will  no longer be filterable, which will seriously degrade system performance. 
 53,  pp. 1079–1081, August 1965. 59. 
 ALARM 
 STATE TRANSMITTER DESIGNS HAVE BEEN BUILT AROUND EACH OF THESE GENERIC FORMS  AND THE COMPONENTS THAT ARE REQUIRED IN THE IMPLEMENTATION OF EACH SHARE SIMILAR CHARACTER 
 The design of such tubes must therefore be a compromise between good RF performance and  good heat dissipation. Unfortunately, these requirements cannot always be satisfied simulta­ neously. Good RF performance usually requires the tube electrodes to be small compared with  a wavelength, while good heat dissipation requires large structures. 
 Sci. Res. ,  vol. 
 Inthis case thelinear feed defines the beam sharpness inregard toazimuth and the reflector dis- tributes the energy inelevation. The ray diagram shown inl’ig. 9.10a will serve again toillustrate the formation ofthe cosecant-squared fan. 
 SANDS MUST BE DRIVEN #OST  WEIGHT  AND COMPLEXITY IS STILL AN ISSUE BECAUSE MULTIPLE PHASE CENTERS NECESSARY FOR ADAPTIVE ARRAY PERFORMANCE REQUIRE MULTIPLE MANIFOLDS 5SUALLY  ONCE A SUBARRAY IS FORMED IN THE MANIFOLDS  IT IS DIGITIZED AND MULTIPLEXED FOR ADAPTIVE SIGNAL PROCESSING !NOTHER IMPORTANT FUNCTION IS BEAM STEERING CONTROL "3#  4HE "3# DOES ARRAY  CALIBRATION  FAILED ELEMENT COMPENSATION    PHASE AND AMPLITUDE SETTING FOR BEAM  STEERING AS WELL AS SPACE 
 Ordinarily, the nose aspect of an aircraft (approaching target) is of principal interest. The commonly used polarizations are horizontal, vertical, and circular. Tabulations of radar cross-section measurements of aircraft sometimes give nose, tail, and broadside values. 
 One of the fundamental  limitations is the foldover of nearby targets; that is, nearby strong ground targets (clutter) can  be quite large and can mask weak multiple-time-around targets appearing at the same place  on the display. Also, more time is required to process the data when resolving ambiguities.  Ambiguities may theoretically be resolved by observing the variation of the echo signal  with time (range). 
 The average improvement  for all filters is indicated by the dotted curve. For comparison, the improvement factor for an  N-l~~lse canceler is sllown in Fig. 4.25. 
 Although the mual SAR optical  processing provides dechirping (matched filtering) or the linear FM pulse-compression  waveform. the chirp modulation of the transmitter is accomplished as in other pulse­ compression radars.  Other aspects of SAR. 
 TECTURE OF THESE SYSTEMS IS CLOSELY PARALLEL TO 2USSIAS  +ONDOR 
 Thismethod ofcolor excitation permitsbetterresolution tobeobtained thanwithconventional TVcolortubes. Therangeorcolors available isnotasgreataswithacolorTVtube,butinmanyinformation­ displayapplications itissufficient. Asimilartechnique usinganode-voltage controlwithtwophosphors havingthesame colorbutdifferent decaytimescanprovideaCRTdisplaywithvariable persistence. 
 As  well as saving design costs, this enables an easy transition to multifunction displays   (MFDs). An MFD can be instantly switched between radar and ECDIS, as well as  other functions, enabling dynamic reconfiguration on a ship to optimize display use  for particular circumstances. Clear indication of the selected mode becomes necessary  for safety and statutory reasons. 
 2.3 Reflection on Dielectric Interfaces   In Radar technology, in addition to metallic objects like airplanes, dielectric objects are also of  interest.  Examples are the Earth’s surface, plants, water, etc.  The waves penetrate, as will be  shown, into the dielectric. 
 Phys., vol. 17, pp. 940-971, November,  1946. 
 DWELL STAGGERING  AN EXTRA TRANSMITTER PULSE ALSO KNOWN AS A FILL PULSE  WILL ENABLE CANCELING OF SECOND RANGE INTERVAL CLUTTER. Ó°{ä  2!$!2 (!.$"//+  7ITH PULSE 
 RECEIVER NOISE !PPLICATIONS THAT UTILIZE HARD LIMITING  INCLUDING PHASE 
 The permissible fre- quency selection is set between 5 and 28 MHz, and antenna radiation is not consid- ered below an elevation angle of 1°. The analyses were made for a radar off the mid- Atlantic coast of the United States and should be a good approximation for any location where transmission paths are through the middle magnetic latitudes. This OTH performance presentation can be used to decide on the antenna patterns and powers required for specific targets and missions, or it can be used to exhibit periods of enhanced or degraded performance for an existing design. 
  
 The doppler spectrum will be like that of Fig. 19.3£. Although it is highly desirable to select a high PRF (HPRF), which is unam- biguous in doppler, it may be necessary in some system applications to use a me- dium PRF (MPRF) and operate with both range and velocity ambiguities (which must be resolved).19 The tail-chase look-down air-to-air scenario is a key exam- ple. 
 BEAM ANTENNA ! NUMBER OF TECHNIQUES MAY BE USED TO AVOID THE PROBLEMS RAISED BY THE PRESENCE OF CLUT 
 Tile  field docs (lot ~wrictr;ite beyorid tlie Iiorizori. Thus, for optical freqi~ericies or very sliort radar  Figure 12.7 Theoretical field strength (relative to free-space field strength) as a function of the distance  from the transmitting antenna. Vertical polarization, h, = h, = 100 m, k = 1, ground conductivity =  10- mlio/rn, dielectric corlstatit = 4. 
 B. Mack. C. 
 The power output, anode voltage, and efficiency are plotted as a function of the magnetron input  power for a fixed frequency and with the magnetron waveguide-load matched. The peak  voltage is seen to vary only slightly with a change in input power, but the power output varies  almost linearly. Figure 6.6h plots the power output and voltage as the tube is tuned through its  frequency range, when the current is held constant and the waveguide load is matched. 
 Costantini, M.; Rosen, P .A. A Generalized Phase Unwrapping Approach for Sparse Data. In Proceedings of the IEEE International Geoscience & Remote Sensing Symposium, Hamburg, Germany, 28 June–2 July 1999. 
 Wu, “Variations of whitecap coverage with wind stress and water temperature,” J. Phys  Oceanogr ., vol. 18, pp. 
 ERROR SENSING 4HIS REQUIRED THAT THE OUTPUT FROM THE LOBES BE COMPARED SIMULTANEOUSLY ON A SINGLE PULSE  ELIMINATING THE EFFECTS OF ECHO AMPLITUDE CHANGE WITH TIME 4HE TECHNIQUE TO ACCOMPLISH THIS WAS INITIALLY CALLED SIMULTANEOUS LOBING  WHICH WAS DESCRIPTIVE OF THE TECHNIQUE ,ATER  THE TERM  MONOPULSE WAS COINED  REFERRING TO THE ABILITY TO OBTAIN ANGLE ERROR INFORMATION ON A SINGLE PULSE )T HAS BECOME THE COMMONLY USED NAME FOR THIS TRACKING TECHNIQUE EVEN THOUGH  THE LOBES ARE GENERATED SIMULTANEOUSLY AND  MONOPULSE TRACKING CAN BE  PERFORMED WITH #7 RADAR 4HE ORIGINAL MONOPULSE TRACKING RADARS SUFFERED IN ANTENNA EFFICIENCY AND COM 
 AIDED FAULT DETERMINATION FOR AN ADVANCED PHASED  ARRAY ANTENNA v PRESENTED AT 0ROC !NTENNA !PPLICATION 3YMP  !LLERTON  ),  3EPTEMBER   * 2ONEN AND 2 ( #LARKE  h-ONITORING TECHNIQUES FOR PHASED 
 Inpractice, thesidelobe levelofaLuneburg lensseemstobeinthevicinityof20 to22dB. Whentheful14rcradiansIJfsolidcoverage isnotrequired, asmallerportionofthelenscan heused,withasavinginsizeandweight.61.62TheLuneburg-Iens principle canalsobeappliedas apassivereflector inamanner analogous toacornerrenector.61Ifareflecting capisplaced overaportionofthespherical lens,anincident waveemerges inthesamedirection fromwhich itentered. Thecapmaybemadetocoverasectoraslargeasahemisphere. 
 Therefore, it is necessary to obtain the RCS curve of the target. If a target contains N anisotropic pixels after discrimination and the RCS curves of the pixels are Rm(k)respectively, where m=1, 2,···,N, we deﬁne the RCS curve of the target as R(k)=N ∑ m=1Rm(k). (3) Figure 4. 
 Target: 5000. tonfreighter. .htenn aheight : 21ft. 
 Norwood, MA: Artech House, Inc., 1978, pp. 375–382. 31. 
 WAY POWER PATTERN OF THE ANTENNA  IS  WHEN  P    PA   WHERE  PA IS  THE HALF 
 8Thelengthsofthevariouslobesillustratedinﬁgures1.5and1.6shouldbe given no special signiﬁcance with respect to the range capabilities of aparticular radar set. As with other coverage diagrams, the lobes are drawn toconnect points of equal ﬁeld intensities. Longer and broader lobes may bedrawn connecting points of equal, but lesser, ﬁeld intensities. 
 Skolnik (ed.). McGraw-Hill Book Co.. New York, 1970. 
 J. L.: An Analytical Approach to the Coverage of a Hemisphere by N Planar Phased  Arrays, IEEE 7'rt111s., vol. AP-15, pp. 
 Elrctrorrics, vol. 28, pp. 142--145,  August, 1955. 
 Perry et al.50 have developed a method  for SAR imaging of ground-moving targets that have unknown straight-line, constant- speed motion. They process the received phase history with a “keystone formatting”  procedure that eliminates the effects of linear range migration for all ground-moving  targets, regardless of their unknown velocity. The processing procedure then automati - cally focuses the moving targets. 
 With good radar maintenance, this accuracy isachieved under field conditions. This was one ofthe most widely used, versatile, and generally successful ofall allied wartime radar sets. 6“16. 
  &&4                           
 It then calculates the range sum as (RT + RR) - cAT,,. A transmitter-to-receiver LOS is not required unless periodic clock synchronization is implemented over the direct path. For the special case of a bistatic radar using the direct range sum estimation method, where L > c&Trt, Eq. 
 l 9a.  This is a Barker code of length t 3. The (+)indicates O phase and ( ) indicates n radians phase. 
 Aspect entropy images of targets. ( a) Dihedral. ( b) Trihedral. 
 It has been shown that the waveform which allows a single pulse-compression filter to be  matched for all doppler-frequency shifts (all target velocities) is2fr-28  [2rr.f/ T ( Bt ) l s(r) = A(t) cos .--8-In l -1~ T (11.55)  The amplitude A(t) of Eq. ( 11.55) represents modulation by a rectangular pulse of width T.  The band occupied by the signal is B, and the carrier frequency isf0. 
 FREQUENCY RADAR PERFORMANCE  PREDICTION MODEL AND 2/4(2 !MCHITKA DATA v .AVAL 2ES ,AB 2EPT  .2,-2 
 Additionally, a pronounced subsidence area located in Hankou district, adjacent to the Xinrong Light Rail Transit station with a maximum velocity exceeding −50 mm/yr, is identiﬁed. Land subsidence is widely found in most areas of the city, and land uplift in surrounding rural areas is also apparent (Figure 4). Four major areas of subsidence are detected: Hankou (HK), Qingshan Industrial Zone (QSIZ), Northern Shahu Lake (NSL), and Baishazhou (BSZ). 
 The factor k is the  gain of the loop formed by the delay line and the feedback path. It must be less than unity for  stable operation. The effect of k < 1 is that the integrator has imperfect "memory." The  optimum value of k depends on the number of pulses received from the target (Sec. 
 1370-1371, September 1979. 12. Steinberg, B. 
 - 4HE GRID 
 VIB included an automatic frequency control (AFC) capability. A highly attenuated sample (about 76 dB of attenuation) of the transmitted pulse was input to a second mixer and the beat frequency between the magnetron and klystron local oscillator was obtained. This signal was passedAirborne Maritime Surveillance Radar, Volume 1 4-14. 
 This chapter explains the special requirements of CMR, both from a practical and  a regulatory point of view, and looks at the technology and system concepts that are  being used to meet these requirements. Until the first decade of the present century,  CMR shipborne technology had been solely based on magnetrons as the basic source  of transmitted power. Since 2004, IMO has encouraged the use of coherent radar solu - tions in an attempt to improve the detection of targets in heavy sea clutter conditions. 
 Theviscousmaterial oftheeyeballis. 466 INTKODUCTION TO RADAR SYSTEMS  affected by heat in much the same manner as the white of an egg. It is transparent at room  temperature but becomes opaque if its temperature is raised excessively. 
 T. A. Weil, “Transmitters,” Chap. 
 Ringel, “The effect of linear FM on the ground clutter in an airborne pulse doppler radar,”  in NAECON '79 Record,  vol. 2, Dayton, OH, May 15–17, 1979, pp. 790–795. 
 Reed, “Adaptive arrays in airborne MTI radar,” IEEE  Trans ., vol. AP-24, pp. 607–615, September 1976. 
 insect^.'^^ Even though they are small, insects are readily detected by radar, and in sufficient  numbers can clutter the display and reduce the capability of a radar to detect desired targets. A  radar cross section of 0.1 cm2, which might correspond to an insect the size of a housefly at K,  band (8.6 cm ~avelength),~' can be detected at a range of about I I nmi by a radar capable of  seeing a 1 m2 target at 200 nmi. Even modest insect concentrations (one insect in 10' m') can  cause angel activity which can be classed as moderate.Io0  At .Y. 
 .. RearPort.Thisisaflatplate-glass window intheconeofacathode-ray tubealignedtobe paralleltothetubefaceplate.34,S?Itallowsslideorfilminformation tobeprojected ontothe. RECEIVERS, DISPLAYS, AND DUPLEXERS 359  back of the tube phosphor, or it can be used to photograph the display without interfering  with the operator. 
   h"ISTATIC 2ADARS (OLD 0ROMISE FOR &UTURE 3YSTEM v  -ICROWAVE 3YSTEMS .EWS   PP n   /CTOBER   % # 4HOMPSON  h"ISTATIC RADAR NONCOOPERATIVE ILLUMINATOR SYNCHRONIZATION TECHNIQUES v IN  0ROC OF THE  )%%% .ATIONAL 2ADAR #ONFERENCE  $ALLAS  48  -ARCH n    * $ 3AHR  h2EMOTE SENSING WITH PASSIVE RADAR AT THE 5NIVERSITY OF 7ASHINGTON v  )%%% 'EOSCIENCE  AND 2EMOTE 3ENSING 3OCIETY .EWSLETTER   PP n  $ECEMBER    h0ASSIVE SYSTEM HINTS AT STEALTH DETECTION SILENT SENTRY! NEW TYPE OF RADAR v  !VIATION 7EEK AND  3PACE 4ECHNOLOGY   .OVEMBER     PP n  * "ANIAK  ' "AKER  ! - #UNNINGHAM  AND , -ARTIN  h3ILENT 3ENTRY4- 0ASSIVE 3URVEILLANCE v  !VIATION 7EEK AND 3PACE 4ECHNOLOGY   *UNE     ! !NDREWS  h($46 
 SCAN FILTERING  EQUATIONS v )2% 4RANS  VOL !# 
 IEEE, vol.  56, p. 2098, November, 1968. 
 AP-16. pp. 553- 568. 
 Nogeneral rules can begiven.. SEC. 17.10] THERADIATION PATH 715 Diffraction Phenomena. 
 EFFECTIVE SOLUTION FOR LARGER ARRAYS  PARTICULARLY AS THE HIGHER POWER CREATES ADDITIONAL COMPLICATIONS FOR PRINTED POWER DIVIDERS 0OOR ANTENNA SITING IS A COMMON CAUSE OF RADAR PERFORMANCE DEGRADATION ON SHIPS  AS WELL AS ON SMALLER CRAFT 0ARTICULARLY ON SHIPS  IT IS SURPRISING THAT INSTALLATIONS ARE STILL BEING IMPLEMENTED THAT CREATE SIGNIFICANT BLOCKAGE TO THE RADAR "LIND ARCS ARE COMMON FROM FUNNELS AND OTHER SUPERSTRUCTURE  AND THERE CAN BE SIGNIFICANT SIDELOBE DEGRADATION DUE TO SMALLER STRUCTURES  SUCH AS 6(& ANTENNAS  CAUSING BLOCKAGE CLOSE TO THE RADAR ANTENNA APERTURE 2& (EAD 4HE 2& HEAD NORMALLY COMPRISES THE TRANSMITTER AND THE RECEIVER  DOWN TO )& OR DIGITAL BASEBAND  AS WELL AS THE ANTENNA AND TURNING GEAR )TS DESIGN FOR BOTH MAGNETRON 
 Many lower levels are  not shown in Figures 5.6 and 5.7; there may be several thousand subprograms in all. Range Doppler Situation.  Modern radars have the luxury of interleaving most  of the modes suggested in Figure 5.2 in real time and selecting the best available time  or aircraft position to invoke each mode as the mission requires.7,9 The geometry that must be solved each time is shown in Figure 5.8. 
 Although generally speaking,  well-matched spatial channels (antenna and receiver) are driven by jamming cancella - tion and antenna sidelobe levels, a second-order requirement results from the need for Transmit Module (1) Transmit Module (m) D1Digital Receiv er (1) Digital  Receiv er (m)… Digital BeamformerT2T1 Adaptiv e  Weight  Generator …Waveform Generator Automatic DetectorDoppler Filter Doppler Filter Doppler Filter T2T1Doppler Filter Doppler Filter Doppler Filter T1, T2;  PRI delaysDm FIGURE 3. 28 Element space post-doppler STAP architecture ch03.indd   30 12/15/07   6:03:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The relative phases and amplitudes of the echo signals from the individtlal  scattering objects as measured at the radar receiver determine the total cross section. The  phases and amplitudes of the individual signals might add to give a large total cross section, or  the relationships with one another might result in total cancellation. In general, the behavior is  somewhere between total reinforcement and total cancellation. 
 After deployment, the antenna can be rotated through 35° from the nadir. Transmit/Receive Modules. During the advanced development stage of large phased array space-based radars, the use of small, low-cost, lightweight low- power T/R modules was proposed in active array configurations.54 Goals for these T/R modules31 included costs of less than $100 each in large mass production and a size of 1 in2, using 0.5 to 1 W of power. 
 Nevertheless,  the functioning of the antenna is complex, and there is need for providing test or mon - itoring circuitry. The decision to point a beam in a certain direction is made some - where in the radar control system and is normally defined by two direction cosines.   A test or monitoring circuit should establish the correct functioning of all compo - nents, including all beam-pointing computations, electronic drivers and phase shifters   or switches, and all their interconnections. 
 Some specially designed gaseous discharge sJrit,ches (hydrogen thyratrons and mercury-sponge series gaps) can also give time jitters ofthesame order ofmagnitude, iftheproper precautions aretaken inthe trigger circuit. Others have time jitters ranging from ~to3~sec forcylindrical series gaps, to20to50ysec forrotary gaps. The simplest type ofpulser isone oftheline type, with a-ccharging and arotary-gap switch. 
 Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters.  SOLID-STATE TRANSMITTERS  11.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11  3. V . 
 The greater the desired radar  range, the more stringent will be the need for reducing the noise modulation accompanying the  transmitter signal. If complete elimination of the direct leakage signal at the receiver could be  achieved, it might not entirely solve the isolation problem since echoes from nearby fixed  targets (clutter) can also contain the noise components of the transmitted signal.6·69  It will be recalled (Sec. 1.3) that the receiver of a pulsed radar is isolated and protected  from the damaging effects of the transmitted pulse by the duplexer, which short-circuits the  receiver input during the transmission period. 
 52, pp. 93-101, February 1982. 49. 
 NOISE POWER RATIO#0)  COHERENT PROCESSING INTERVAL#7  CONTINUOUS WAVE$ !:  DELTA 
 BORNE  POLARIMETRIC INTERFEROMETRY USING THE !,/3 
 Figure 10.6 shows a sketch of a SAW pulse compression device with disper- sive input and output transducers. As the energy in a SAW device is concen- trated in its surface wave, the SAW approach is much more efficient than bulk- wave devices, where the wave travels through the crystal. The propagation velocity of the surface wave is in the range of 1500 to 4000 m/s, depending on the crystal material, and allows a large delay in a compact device. 
 PARABOLIC IONOSPHERE v  2ADIO 3CIENCE  VOL    PP n    4 ! #ROFT AND ( (OOGASIAN  h%XACT RAY CALCULATIONS IN A QUASI 
 294 1NTKOl)UC"FION TO KAI)AK SYSI'EMS  shift. This is called a Irrrc-l~itl!j plicrse slrjfier. Thi~s a single, short-clurat ion cirrrent pulse sets the  phase. 
 T. Ransone, Jr., and W. T. 
 With modern narrow antenna beams and customary scanning rates the time occupied bythis group isalways short compared with the total scanning time and achievable decay times. The screen chosen should have sufficient persistence sothat there isnoappreciable decay’ during theprocess ofscanning across thetarget and theentire echo arcisobserv- able atone time. Inorder that the average intensity ofthis arcshall represent allofthedata, itisessential that thescreen integrate theeffects ofallthepulses that overlap onagiven focal spot—that is,itshould not 1Except forthat involved inthedisappearance ofthesecalled “flash,” which occurs foravery short time interval during andimmediately after each excitation.. 
 CAL  AND THEIR VOLUMES DIFFER AT MOST BY A FACTOR OF  %XCEPT FOR THE SPHERE  WHOSE GEOMETRIC 
 11.9~. The contour for zero velocity is triangular in shape and represents the  autocorrelation function of a rectangular pulse such as would be predicted from Eq. (1 1.52). 
 Mks. VA, III & VI, C.C.D.U. Trial Report No. 
 AGC is neces- sary to keep the gain of the angle-tracking loops constant for stable automatic angle tracking. Figure 18.9 is a block diagram of a typical monopulse radar. The sum signal, elevation difference signal, and azimuth difference signal are each converted to intermediate frequency (IF), using a common local oscillator to maintain relative phase at IF. 
 FREQUENCY PROCESSING OF SYNTHETIC APERTURE RADAR  SIGNALS v  )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS   VOL   NO   PP n   !PRIL   & - 3TAUDAHER  h!IRBORNE -4) v #HAPTER  IN  2ADAR (ANDBOOK  - 3KOLNIK ED   ND %D   .EW 9ORK -C'RAW 
      WHERE - IS THE LENGTH OF THE &)2 FILTER IMPULSE RESPONSE   HN     
 281. Sensors 2019 ,19, 1154 Phase compensation and ISAR imaging can be written as follows [ 23,32,35]: I(k,n)= IFFT 2D{R(k,n)·exp(−jφ(m))} (8) where I(k,n)is the SAR image, φ(m)represents the phase error in Equation (2). mis the number of samples in the range direction, nis the cross-range samples number. 
 (At microwave frequencies the backscatter from  rain has far greater effect on radar performance than the attenuation. The opposite is true in  the millimeter-wave region.) The effect or a fog with 300-m visibility is seen to increase slightly  the clear-air attenuation. A fair-weather cumulus cloud has low attenuation at millimeter  wavelengths. 
 14.5 of ref. 47.  61. 
   (& /6%2 
 VAissobiased that only thelarge pulse lifts thegrid past cutoff. Since thetotal delay ofthis pulse is6psec, itsarrival will coincide with that ofthethird undelayed pulse onthesuppressor ofV,. Atthis time, and this time only, theplate ofV4receives asignal and fires Vs.. 
 The dechirped  and partially filtered or compressed output, shown at point C in Figure 5.34, may be  resampled again at a new fS, as indicated in the right graph shown in Figure 5.35, point  C. In any case, azimuth variable phase adjustment and bin mapping (which compen - sates for changes in measurement space angles and range closure since significant  motion occurs during the data gathering time) must be performed before azimuth filter - ing (sometimes called compression because it is similar to phase matched pulse com - pression). The output of azimuth compression is shown at point C. 
 Aconstant echosignalwithrange,however, isprobably notas important anapplication ofthecosecant-squared patternasisachieving thedesiredelevation coverage inanefficient manner. Shaping ofthebeamisdesirable sincetheneededrangeat highanglesislessthatatlowangles;hence,theantenna gainasafunction ofelevation angle canbetailoredaccordingly. Shapedpatterns likethecosecant-squared patternarealsousedin airborne radarsthatmapthesurfaceoftheearth.89 Antenna design.Thedesignofacosecant-squared antenna patternisanapplication ofthe synthesis techniques discussed inthepreceding section.Examples ofcosecant-squared-pattern synthesis aregivenintheliterature.7•73,77,9o Thecosecant-squared patternmaybeapproximated withareflector antenna byshaping thesurfaceorbyusingmorethanonefeed.Thepatternproduced inthismannermaynotbeas accurate asmightbeproduced byawell-designed arrayantenna, butoperationally, itisnot necessary toapproximate thecosecant-squared patternveryprecisely. 
 Wind speed with errors of about 2 m/s and a wind direction error of less than 16° are sought. SBR altimeters expect to measure altitude with an error of 5 cm from a 1300-km polar orbit inclined 65° over the ocean. Over the solid surface of Mars, a 37-GHz altimeter on the Mars orbiter mission expects to gather global high-resolution topographic mapping data with a height resolution of 15 m. 
 These systems usually are not designed to detect and process the echoes from targets illuminated by the transmitter. They can, however, be used with a bistatic or multistatic radar to identify and locate a suitable transmitter to initialize radar operations. Thus, while they have many requirements and char- acteristics common to multistatic radars, they are not radars and will not be con- sidered here. 
 Hardy, K. R., and I. Katz: Probing the Clear Atmosphere with High Power, High Resolution  Radars, Proc. 
 191. J. S. 
 Through the above analysis, we can conclude that, compared with the traditional ArcSAR imaging algorithm, the imaging method proposed in this paper can eﬀectively improve the deformation monitoring accuracy. 6. Experiment We used a distributed scenes imaging experiment of ArcSAR to verify the e ﬀectiveness of the proposed high-precision imaging method. 
 #ARRIER &-  ,INEAR FREQUENCY MODULATION &-  OF THE CARRIER CAN BE USED  TO MEASURE RANGE 4HE MODULATION AND DEMODULATION TO OBTAIN RANGE ARE THE SAME AS USED IN FREQUENCY 
 27.Sandler, S.S.:Paraboloidal Reflector Patterns ofOff-axis Feed,IRETrailS.,vol.AP-8,pp.368-379, July,1960. 28.Ruze,1.:LateralFeedDisplacement inaParaboloid, IEEETram.,vol.AP-I3,pp.660665,Sepkm­ ber,1965. 29.Imbriale, W.A.,P.G.Ingerson, andW.C.Wong:LargeLateralFeedDisplacements inaParabolic Reflector, IEEETrans.,vol.AP-22,pp.742-745, November, 1974. 
 135  13.3 Automotive Radar (ACC) ............................................................................................. 141  13.3.1 History ................................................................................................................... 141  13.3.2 Automobile Radar System Parameters ................................................................. 
 The criterion for determining the level of the decision  threshold is to set the threshold so it produces an acceptable predetermined average  rate of false alarms due to receiver noise. After the detection decision is made, the track of a target can be determined, where  a track is the locus of target locations measured over time. This is an example of data  processing . 
 ....6+0to–10~0 Number oftubes Transmitter-receiver, 31tubes and 3crystals Synchronizer ... ., ., 25 Indicator ...,..... ,,... 
 Sivan, “The modulator,” Chap. 9 in Microwave Tube Transmitters , London: Chapman   & Hall, 1994. 48. 
 Thefrequency-response function ofthedilpersive delay lineusedforgenerating thetransmitted waveform istheconjugate ofthatofthepulse­ compression filter.InthespecialcaseofthelinearFMwaveform thesamedispersive delayline thatgenerates thetransmitted waveform maybeusedasthereceiver matched filterifthe received waveform ismixedwithanLOwhosefrequency isgreaterthanthatofthereceived signal.Thisresultsinatimeinversion (itchangess(t)tos(-t))byconverting anincreasing FM toadecreasing FM,orviceversa. Dispersive delaylines.Therehavebeenanumberofdevicesusedasdispersive delaylines,or pulse-compression filters,forlinearFMwaveforms.16Theymaybeclassedasultrasonic, electromagnetic, ordigital.Ultrasonic delaylinesincludethoseofaluminum orsteelstrip, piezoelectric materials suchasquartzwithpropagation takingplacethrough thebulk(or volume) ofthematerial, piezoelectric materials withthepropagation takingplacealongthe surface(surface acoustic wave),andYIG(yttrium-iron-garnet) crystals. Theall-pass, time delayusingbridged-T networks witheitherlumped-constant circuitelements orstripline; the waveguide operated nearitscutofffrequency; andthetapered folded-tape meander lineare examples ofelectromagnetic dispersive delaylinessuitable forlinear-FM pulsecompression. 
 POWER  DESIGN  THE LOAD IMPEDANCE PRESENTED TO THE FINAL DEVICE MUST BE CAREFULLY CHOSEN  SUCH THAT POWER OUTPUT AND EFFICIENCY ARE MAXIMIZED !LSO  TOO MUCH GATE PERIPHERY MAY INCREASE THE CHIP AREA SUCH THAT COST OF THE COMPONENT BECOMES UNATTRACTIVE    ,OSSES IN THE OUTPUT CIRCUIT OF THE FINAL STAGE CAN SIGNIFICANTLY REDUCE POWER OUTPUT AND EFFICIENCY /FF 
 58, pp. 148-15 l.  70. 
 Buying radar range with transmitter power  alone can therefore he costly.  Thus there arc many diverse requirements and system constraints that enter into the  selection and design of a transmitter. This chapter briefly reviews the various types of transmit­ ter tubes and their characteristics. 
 ", 
 UTED SCATTERERS v 0T )  #AN * 0HYS  VOL   PP n    0 2 7ALLACE  h4HE INTERPRETATION OF THE FLUCTUATING ECHO FOR RANDOMLY DISTRIBUTED SCATTERERS v 0T  ))  #AN * 0HYS  VOL   PP n    $ 3 :RNIC  h3IMULATION OF WEATHER 
 The subarrays are displaced from each other by two ele- ments in the example. Another variant is to have separate corporate feeds for the left and right subarrays of the antenna.11 One of the subarrays or a central group of elements is(a) (b) FIG. 16.9 Physical DPCA defining geom- etry, (a) Perfect motion compensation, where A1 and A2 are the antenna phase centers for pulse 1 and the primed quanti- ties are for pulse 2. 
 The ideal adaptive antenna acts automatically to adjust itself as a matched  (spatial) filter by reducing the sidelobes in the direction of the unwanted signals. Adaptive  arltenrlas require some a priori knowledge of the desired signal, such as its direction,  waveform, or stat istical properties.  If all the elements of an adaptive phased-array antenna have a separate adaptive control  loop, it is called a $tlly ariaprirlr array. 
 Just as is done in antenna design, the filter sidelobe can be reduced by  using Cliebyshev, Taylor, sin2 .u/.u2, or other ~eightings.~' (In the digital signal processing  literature, filter weighting is called window it^^.^^ Two popular forms of windows are the  Ha~rlrning and I~anning.) It may not be convenient to display the outputs of all the doppler  filters of !lie filter bank. One approach is to connect the output of the filters to a greatest-of  circuit so tliat only a single output is obtained, that of the largest signal. (The filter at dc which  contains clutter would not be inc!uded.)  . 
 Deley,12 Courtesy McGraw-Hill Book Company.)  ambiguity diagram, may be used to assess qualitatively how well a waveform can achieve these  requirements. Each of these will be discussed briefly.  If the receiver is designed as a matched filter for the particular transmitted waveform, the  probability 6f detection is independent of the shape of the waveform and depends only upon  EIN,, the ratio of the total energy E contained in the signal to the noise power per unit  bandwidth. 
 63. Nicholson, A. M., and G. 
 All ﬁgures in Table 3are given in units of TECU (1 TECU = 1016electrons/m2). 207. Sensors 2019 ,19, 516 T able 3. 
 RITHMS HAVE BEEN DEVELOPED THAT CORRECT 33( DATA FOR THE EFFECTS OF THE LARGER CROSS 
 Sun-Synchronous Orbits . Sun-synchronous satellites host European Space  Agency (ESA) altimeters on ERS-1, ERS-2, and RA-1 on ENVISAT. All share the  same orbit: 35.00 calendar days repeat period; 98.5 ° inclination; and 781-km mean  equatorial altitude. 
 GPR system design can be classified into two groups. GPR systems that transmit an  impulse and receive the reflected signal from the target using a sampling receiver can  be considered to operate in the time domain. GPR systems that transmit individual fre - quencies in a sequential manner and receive the reflected signal from the target using a  frequency conversion receiver can be considered to operate in the frequency domain. 
 ,UPE  )SRAELS 4EC3!2  AND "RAZILS  -AP3!2 ARE GOOD EXAMPLES  )F A REFLECTOR IS DRIVEN BY  MULTIPLE FEEDS  THEN ONE MAY STILL EFFECT BEAM STEERING  ALTHOUGH WITH RATHER LESS BEAM SHAPE VARIETY AND CONTROL THAN THROUGH AN %3! 3PACE 
 Thefundamental properties oftheambiguity function prohibit thistypeofidealized behavior. Thetwochief restrictions arethatthemaximum heightofthe IX12function be(2£)2andthatthevolume underthesurfacebefiniteandequal(2£)2.Therefore thepeakattheoriginisoffixedheight andthefunction encloses afixedvolume. Areasonable approximation totheidealambiguity diagram mightappearasinFig.11.8.Thiswaveform doesnotresultinambiguities sincethere isonlyonepeak,butthesinglepeakmightbetoobroadtosatisfytherequirements of accuracy andresolution. 
  
 Thedirection ofpolarization isdefinedasthedirection oftheelectricfield vector.Mostradarantennas arelinearlypolarized; thatis,thedirection oftheelectricfield vectoriseitherverticalorhorizontal. Thepolarization mayalsobeelliptical orcircular. Elliptical polarization maybeconsidered asthecombination oftwolinearlypolarized waves ofthesamefrequency, traveling inthesamedirection, whichareperpendicular toeachotherin space.Therelativeamplitudes ofthetwowavesandthephaserelationship between themcan assumeanyvalues.Iftheamplitudes ofthetwowavesareequal,andiftheyare90°outof (time)phase,thepolarization iscircular. 
 These applications transmit a short-duration phase-coded pulse, and (b) FIG. 10.13 Digital correlation with (a) fixed and (b) variable references.INPUT SEQUENCESHIFT REGISTER CORRELRTION FUNCTION U) REFERENCE SR REFERENCE SEQUENCE INPUT SEQUENCECOMPflRISON COUNTERCORRELRTION FUNCTION SIGNRL SR . the phase shift due to doppler over each expanded pulse width is negligible. 
 CHRONIZATION IN TIME TO ALLOCATE TRANSMISSION AND RECEPTION WINDOWS AND TO SYNCHRONIZE TIMEBASES 7HEN EXISTING WAVEFORMS MUST BE USED  THIS CAN PRESENT CHALLENGES %XISTING APERTURE SCHEDULING ALGORITHMS CAN THEN ALLOCATE TIME FOR TRANSMISSION OR RECEPTION  4O ACHIEVE VERY HIGH THROUGHPUTS  PHASE LINEARITY IN TRANSMIT AND RECEIVE PATHS  IS CRITICAL SINCE DATA TRANSMISSION WAVEFORMS RELY ON MODULATION THAT IS EVERY BIT AS COMPLEX AS MANY RADAR MODES 4HIS CAN ALSO IMPACT CHOICE OF TAPER FUNCTION BECAUSE ANGULAR VARIATIONS IN PHASE ACROSS THE MAIN 
 Thecomputer isneededinaphased-array radartoprovide hearn-steering commands for theindividual phaseshifters; signalmanagement bydetermining thetypeofwavdorm, the numberofobservations, datarate,power,andfrequency; thecorresponding signalprocessillg anddataprocessing inaccordance withthemodeofoperation; outputsofprocessed dawto. TttE EI.EC'I RON1CALI.Y SrEEREU PHASED ARRAY ANTENNA IN RADAR 323  users. including tlie gerieratiorl of displays; " holrsekeepi~~g " functions of performance monitor-  ing. 
 Miller, R. E., T. G. 
 45. D. C. 
  XI 
 296. Sensors 2019 ,19,6 3 2. Materials and Methods 2.1. 
 _ __.__J__J.......J.....J....-L...L-L- __ _J  0.1 0.2 0.3 0.4 0.5 0.8 1.0 2 3 4 5 6 8 10 20  Circumference/ wavelength = 2 rr a/ X  Figure 2.9 Radar cross section of the sphere. a = radius; l = wavelength.  interest to the radar engineer because the cross sections of raindrops and other meteorological  particles fall within this region at the usual radar frequencies. 
 Sometimes the bandwidth of a radar receiver is in excess of the optimum to allow for some offset between the echo spectrum and the filter bandpass, caused by target velocity and receiver tuning tolerances. Although this makes the radar more susceptible to off-frequency narrowband interference (Fig. 3.8), it reduces the time required to recover from impulse interference (Fig. 
 The receiver was the standard model for ASV Mk. II. A speciallydesigned switch was used to change the transmitter between homing and broadside aerials. 
 The relationship between hand Slosscan be expressed as: Sloss=10lg⎛ ⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎝⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsinglei=θ 2⎭summationtext i=−θ 2exp⎭parenleftbigg j4πf cΔR(i,h)⎭parenrightbigg θ⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎞ ⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎠2 (31) The necessary parameters are given in Table 1. The h–Slosscurve is shown in Figure 11. Figure 11. 
 The British Type 7equipment isthemost widely used radar exploiting Firstlobe,antenna1this signal-comparison principle. Firstlobe,antenna 2Acopy ofthis equipment built in . Canada for the United States is\called theSCR-588; American-built\ G // \ \ redesigns ofthe same basic equip- /,\ g 1/ \ meut are the SCR-527 and the ~\ SCR-627. 
 This differs sharply from heavy rain, where this ratio can be as large as 6 dB. The combination of absolute reflectivity factor at horizontal polarization and ra- tio of reflectivities at horizontal and vertical polarizations (differential reflectivity) gives unique signatures for hail and heavy rain, each of which is characterized by high reflectivity factor. The difference in the differential reflectivity signatures is eas- ily explained. 
 A jntnrncr that operates outside the range of normal defenses is  known as a stcrr~d-c?(;/'itr~?~~r~t~~'. An important ECCM tactic is to engage hostile jammers with  I~orric~-orr-/trru (tlOJ) missile giritiancc. If the jammer is radiating, HOJ is generally a better  guidance tecl.rniquc tliaii is radar guidance. 
 The effects of propagation will modify tlie free-space performance of the radar. as  well as introduce errors in the radar measurements.  It is usually convenient to distinguish between two different regions when considering  radar propagation. 
 5.8. Resolution in range of the  individual target scattering-centers permits an angle measurement of the scatterer without the  errors introduced by the glint caused by multiple scatterers within the same resolution cell.  This provides a three-dimensional " imageT' of the target and thus presents more target infor-  mation from which to derive a classification than do& a conventional high-range-resolution  radar without monopulse. 
 310, pp. 1929–1933, December 23, 2005. ch18.indd   70 12/19/07   5:15:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The receiver R.3132B included additional spark gap protection and a switch to disengage its internal aerial switch unit, which was notrequired. An illustration of the aerial coupling box type 8 is shown in ﬁgure2.18, and ﬁgure 2.19 shows a schematic of the switching arrangement. It relied on accurately matched half-wave and quarter-wave lines, combined with spark gap switches Figure 2.17. 
 IEEE T rans. Antennas Propag. 1999 ,47, 1179–1188. 
 TION ITSELF 4HE ACCUMULATION OF THE APPLIED PHASE SHIFT FROM SWEEP TO SWEEP  HOWEVER  MUST BE PERFORMED DIRECTLY ON THE PHASE AND IS COMPUTED MODULO  O 4HE NUMBER OF  ZEROS OF THE ADAPTIVE -4) SECTION IS AGAIN DETERMINED BY THE REQUIRED IMPROVEMENT FACTOR AND THE EXPECTED SPECTRAL SPREAD OF THE  CLUTTER 4HE PHASE SHIFT IS APPLIED TO THE  INPUT DATA IN THE FORM OF A  COMPLEX MULTIPLY  WHICH AGAIN REQUI RES THE TRANSFORMATION  OF THE PHASE ANGLE INTO RECTANGULAR COORDINATES 4HIS TRANSFORMATION CAN EASILY BE PERFORMED BY A TABLE LOOKUP OPERATION IN A READ 
 TV satellites as illuminators).  Development in this direction is strongly enforced and not only in the military.  . 
 THE 
 IEEE Geosci. Remote Sens. Lett. 
 PULSE OR A BATCH 
 TERS ARE ALMOST NEVER USED IN RADAR SYSTEMS FOR THESE AND A VARIETY OF HISTORICAL REASONS  A CAUTIOUS DESIGNER MIGHT FIND AN APPLICATION WHERE THEY CAN BE USED TO GOOD ADVANTAGE "Y CONTRAST  &)2 FILTERS ARE INHERENTLY STABLE 2EAL &)2 FILTERS WITH SYMMETRIC COEF 
 As shown in Figure 17.1 b, these N time-domain  echoes may be processed using a DFT to produce a set of N frequency-domain returns.  The frequency interval between successive returns is ∆f = 1/T, and the overall fre - quency interval is ( N − 1)/T ≈ N/T = PRF = fR. We assume operation at baseband, and  thus the frequency in question is the apparent doppler frequency of the targets. 
 9, pp. 12-20, 1956.  19. 
   PP n  !PRIL   , 2 2ABINER ET AL  h4ERMINOLOGY IN DIGITAL SIGNAL PROCESSING v  )%%% 4RANS ON !UDIO AND  %LECTROACOUSTICS  VOL !5 
 Furthermore, based on (17) and (19), we have: N≥k+2, (20) which means that more ﬂight passes allow more azimuth sidelobes to be removed. Figure 4illustrates the process of the parameter selection. In summary, the integrating range can be computed based on (14), and the baseline B, the ﬂight angleα, and the number of passes 2 N+1, can be optimized using (17), (19), and (20). 
 BASED RADAR ALTIMETERS WORK  BEST OVER RELATIVELY MILD TOPOGRAPHIC RELIEF OF MEAN SLOPE ZERO  SUCH AS THE OCEANS SURFACE /VER ICE SHEETS OR TERRESTRIAL SURFACES  PERFORMANCE IS DEGRADED 5NWANTED CHARACTERISTICS INCLUDE FOOTPRINT DILATION  OVER ROUGHER TERRAIN  HEIGHT ERRORS IN PROPOR 
 A small voltage applied to the control grid acts to  control the number of electrons traveling from cathode to anode. The process by which  the electron density of the electron stream is modulated by the signal on the control  grid to produce amplification is called density modulation . In the latter half of the 20th  century, grid-controlled tubes were successfully employed in such important radar  applications as HF over-the-horizon radar, VHF and UHF aircraft surveillance radars,  and satellite surveillance radars. 
 ITherotating diskismounted onbearings inside thevacuum andcoupled toarotating mechanism outsidethevacuum. TheAmperex X-band DX-285 spin-tuned magnetron coversa500-MHz bandinanapproximately sinusoidal manneratratesupto1000timespersecond,equivalent tofrequency tuningratesoftheorder ofIMHzpermicrosecond. !\.coaxialmagnetron maybetunedbymechanically positioning inthecoaxialcavitya noncontacting washer-shaped metalring,ortuningpiston,asillustrated inFig.6.8.The tuningpistoncanbepositioned mechanically fromoutsidethevacuum bymeansoravacuum bellows. 
 For ASV operation, the mixer current, mixer coupling, PPI focus, PPI brightness, height tube brightness and course marker were pre-set on the ground but could beadjusted by the operator if necessary. The gain control on the switch unit would be varied continually during search between the level that gave bright noise scintilla- tions on the PPI and the level at which sea returns extended to only 1 –2 miles. The gain would be kept as low as possible once a contact was obtained. 
 When an equal-path-length feed is not in use, the feed network will  produce a change in phase with frequency. In some cases, such as Rotman lens83 or  equal-length Blass matrix84, the feed can actually compensate for the aperture effect  and produce a beam direction that is independent of frequency. However, the more  conventional feeds tend to reduce the bandwidth of the array. 
 10.6b. Figures 10.6 and 10.7 illustrate the so-called “r-mode” inwhich magnetrons normally operate; (mrefers tothe phase difference between adjacent anode segments). Actually, the number ofpossible modes of. 
 Chapter 16describes anextremely elegant method bymeans ofwhich agiven target can bereadily distinguished from itssurroundings, pro- viding itisinmotion with respect tothose surroundings and that they areatrest orhave auniform mass motion. The following paragraphs will dk.cuss another aspect ofthe discrim- ination problem—that ofthe presentation ofamultiple orcomplex picture when itisnot desired tosuppress any ofthe information but rather topresent itinmdetailed amanner aspossible. 13.20. 
 The PRFs are calculated as 16.25·1400/13, 16.25·1400/18, 16.25·1400/15,  and 16.25·1400/19. The PRFs would be about 1750, 1264, 1517, and 1197 Hz. 2.17 CONSIDERATIONS APPLICABLE   TO MTI RADAR SYSTEMS MTI radar system design encompasses much more than signal processor design. 
 DOPPLER SYSTEM  GIVES THE MAXIMUM NUMBER OF INDEPENDENT SAMPLES FOR A GIVEN DISTANCE TRAVELED ALONG THE GROUND &)'52%     !CCURACY OF AVERAGES FOR FADING  SIGNALS.   '2/5.$ %#(/  £È°Óx .EAR 
 The necessity forconnecting such units with cables adds considerably tothetotal weight oftheset, however, and thephysical fayout must be carefully planned toreduce the number ofcables and tokeep their lengths assmall aspossible. Equipment mounted inaircraft issubject toextreme variations of pressure and temperature. External airpressure can vary from that at sealevel tothe pressure ofless than one-quarter atmosphere found at 30,000 ft. 
 26.3 REFRACTION2 Index of Refraction.  The term refraction  refers to the property of a medium  to bend an electromagnetic wave as it passes through the medium. A measure of the  amount of refraction is the index of refraction, n, defined as the velocity, c, of propaga - tion in free-space (away from the influence of the Earth or other objects) to the veloc - ity, v, in the medium. 
 25.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 This error voltage limits the theoretical maximum SNR of an ADC by  SNRmax = 20log( A/Ve) = –20log[(2 p  f tJ]  This relationship is presented in Figure 25.20, which plots on the left and right  axes, respectively, the SNR and the equivalent ADC effective number of bits or ENOB   (≈ SNR/6 dB), both versus analog frequency and for different values of RMS sample  jitter. Due to a variety of error sources internal to an ADC (aperture uncertainty, non - linearities, added noise, etc.), the specified ENOB of an ADC is always less than the  number of bits it provides. For example, a 14-bit ADC typically has an ENOB of 12. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.596x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 at each element may result in situations where a solution does not exist.102 An example  of a deterministic antenna pattern with and without nulling is shown in Figure 13.40.  The solid line in Figure 13.40 shows a deterministic antenna pattern at broadside for  a 25-element linear array with l /2 element spacing when no interference is present. 
 PLES ARE   MISSILE DEFENSE RADAR    SPACE 
 3.30 and b. The configuration of Fig. 3.3a suppresses all spurious IF frequencies and spu- rious RF responses derived from even harmonics of the signal frequency. 
 2.5. Asimple range time base, orA-scope, was used; thevideo bandwidth was sowide (10Me/see) astohave anegligible influence onthe outcome, atleast in. 34 TIIERADAR EQUATION [Sm.29 theneighborhood oftheminimum. 
 This  anode we arrange as a large metal ring around the  cathode, and we surround the whole with a powerful  magnet, and whirl the electrons out of their course.  . 118 HOW RADAR WORKS  So fierce is this whirlpool of electrons that we can switch  off the filament almost immediately, and, provided the  magnetic field is maintained, we have a stream of  electrons continuously whirling around inside the metal  anode ring. 
 M IN  LENGTH WHOSE FAN 
 Multifrequency compressed sensing for 2-Dnear-ﬁeld synthetic aperture radar image reconstruction. IEEE T rans. Instrum. 
 (The clutter residue is the clutter power remaining at the output of  an MTI system.)  Cancellation ratio. The ratio of canceler voltage amplification for the fixed-target echoes  received with a fixed antenna, to the gain for a single pulse passing tllrotlgh the Lrn-  processed channel of the canceler.  The improvement factor (I) is equal to the subclutter visibility (SCV) times the clutter  visibility factor (Kc). 
 SURED DATA VERIFYING THE ANTICIPATED PERFORMANCE OF THE HIGHEST PRECISION TRACKING RADAR AT THAT TIME &)'52%  !ZIMUTH 
 Offsetfeed.1Boththeaperture blocking andthemismatch atthefeedareeliminated withthe offset-feed parabolic antenna showninFig.7.10.Thecenterofthefeedisplacedatthefocusof theparabola, butthehornistippedwithrespecttotheparabola's axis.Themajorportionof thelowerhalfoftheparabola isremoved, leavingthatportionshownbythesolidcurvein Fig.7.10.Forallpractical purposes thefeedisoutofthepathofthereflected energy,sothat thereisnopatterndeterioration duetoaperture blocl~ing noristhereanysignificant amount ofenergyintercepted bythefeedtoproduce animpedance mismatch. Itshouldbenotedthattheantenna aperture ofanoffsetparabola (oranyparabolic reRector) istheareaprojected onaplaneperpendicular toitsaxisandisnotthesurfacearea. Theoffsetparabola eliminates twoofthemajorlimitations ofrearorfrontfeeds. 
 (1)also shows that forv<Et/H, the electromagnetic force will bereduced and the electrons will bedeflected inthe direction ofthe electric force. For v>Et/H,the deflection will beinthedirection ofthemagnetic force. The deflection that anelectron suffers inthis example when speeded uporslowed down thus corresponds towhat happens inamagnetron and itissignificant that the operating conditions areones forwhich v=Et/H. 
   "&  &     +    + &)'52%   %XPERIMENTAL MEASUREMENTS OF ONE 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft.  MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 geometrical correction and motion compensation. 
 Any practical  device iq ricvcr perfect: it will always he cotistructed with some error, albeit small. The phase  variations due to the uriavoidable errors can cause the sidelobe level to be raised and the gain  to be lowered. Tllcre is a practical limit beyond which it becomes increasingly difficult to  achieve low sidelobes even if a considerable amplitude taper is used. 
 , 2ADAR TRANSMITTER DESIGN INVARIABLY REQUIRES SIGNIFICANT RADIATED POWER FROM THE  ANTENNA IN ORDER TO PROJECT TO THE MINIMUM RANGE REQUIREMENT WHILE MAINTAINING SOME MINIMUM SIGNAL 
 ch26.indd   18 12/15/07   4:53:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation. 
 Liu, X.T.; Cao, Q.X.; Xiong, Z.G.; Yin, H.T.; Xiao, G.R. Application of small baseline subsets d-insar technique to estimate time series land deformation of Jinan area, China. J. 
 BROADENING TECHNIQUE  THE TRANSMIT PULSE SEGMENT IN EACH BEAM POSITION WOULD BE .  TIMES AS LONG AS THE TRANSMIT PULSE IN THE BEAM 
 FLIGHT DATA UPLINKDOWNLINK  TARGET CLASSIFICA 
 on Radar Meteorol. , Munich, AMS, pp. 154–156, 2001. 
 vol. 66, pp. 563-583, May, 1978. 
 Thus, if each scatterer is a tree, the  waving of the trees as the wind blows causes relative phase shifts between the separate  scatterers; the result is fading. For a fixed radar, this may be the only fading observed,  except for very slow fading due to changes in refraction. If the surface elements are  stiff, they may not move enough to get significant doppler spreading, and the fading  distribution may not be close to Rayleigh. 
 angle95 – 157 1988103 The University  of Michigan   EE / CS Dept.Ulaby et al. Visually smooth sand   Rough sand Gravel17 / 10 35  VV HH   VH HV   VH HV66 60 6066 60 10 – 800 – 170   0 – 170   0 – 90 1992104 MIT Lincoln  Lab., MAKochanski Sea (sea state 1) 3 / 3 10 VH VV 89.7 50 – 85 180 1994105 1995106 2002107 Northeastern  Univ., MA Northeastern  Univ., MA Univ. of MAMcLaughlin  et al. 
 TRIBUTIONS 3PAULDING AND 7ASHBURN  ADDED DATA FROM THE FORMER 5332 FOR TWO  REVISED ##)2 REPORTS .OISE 
    /#", -2 ,1"*,0 &0&/1/"00 &0&/1/"00                     !    /&.2&,$4&%*", '           
 STRAINED SPATIAL AND SPATIO 
 G. Hansen  and J. R. 
 A. Barley, and G. J. 
 —Magnetic B-scopes ofvarying degrees ofcom- plexity have been used. Ifthe center ofthe display istoremain fixed inangle, apotentiometer isusually employed and the only essential depart ure from A-scope design isinthe amplifiers. Inmany applica- tions, however, more flexibility isdesired, requiring more complicated methods. 
 ERATING THE RADAR WAVEFORM 4HE PHASE CONTROL ELEMENT SUPPLIES DIGITAL SAMPLES OF THE IN 
 The RF conversion efficiency of klystron amplifiers as used for radar might  range from 35 to 50 percent. The less the bandwidth of the klystron, the greater can he its  effi~iency.~~ However, by use of harmonic bunching of the electron beam, high-power CW  klystrons of wide bandwidth have demonstrated efficiencies as high as 70 to 75 percent."  The advantage of the klystron over other microwave tubes in producing high power is due  to its geometry. The regions of beam formation, RF interaction, and beam collection are  separate and independent in the klystron. 
 ahazclayerintheairbelowthetemperature inversion canbeobserved. Thcaltitude ofthetradewind ductvariesfromhundreds ofmetersattheeasternpartofthetropical oceans tothousands ofmetersatthewestern end.Thus,theheightgradually risesingoingfromeast tov.'est,Thereisalsoageneral decrease oftherefractivity gradients tothewest.Offthe southern California coast.inthevicinityofSanDiego,theboundary between moistanddry airisrelatively stableandexistsatanaveragealtitude of300to500meters.Sincetheelevated ductisduetometeorological effectsthereareseasonal, aswellasdiurnal, variations. The optimum seasonforductformation inthetradewind regionbetween BrazilandAscension IslandsoccursinNovember.29Ithasbeensaid,however, thatelevated ductsgivingriseto strongpersistent anomalous propagation occurthroughout mostoftheyearoveratleast one-third oftheoceans.27 Totakemaximum advantage ofpropagation inanelevated duct,theradarandtarget shouldbeatanaltitude ncarthatoftheduct.Thisisfoundfromboththeoryandmeasure­ mcntsmadebyaircraftOyingatvariousaltitudes.Itwasnoted,30 however, thatthepropaga­ tionofelectromagnetic energyfromantennas wel1belowtheductisgreaterthanwouldbe predictcdfromc1assicaIraytheory. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 widely available, including anechoic chambers, indoor compact ranges, and outdoor  test fields.72 Full-scale experimental measurements can be made in some circum - stances by means of calibrated reference scatterers or transponders deployed in the  target zone and modulated to separate their returns from the target and clutter echoes. 
 15.8. Itisahorn-fed paraboloid cutto 8ftby4ft. Despite thegreater beamwidth ofthebeacon antenna than that ofthe radar antenna, the beacon signals arealmost asnarrow in. 
 SQUARE DENSITY OR  LOG 
 135. Gabriel, W. F.: Adaptive Array Antennas for AEW Radar, Repori of NRL Proyrr.~.~, pp. 
 For best use of theavailable space, thereceiver chassis isintheform ofasegment ofa circle. The normal chain ofi-famplifier stages, second detector, and video output stage, isarranged around theperiphery. The bandwidth of thei-famplifier is5Me/see, but forlong-pulse operation arelay switches thebandwidth to1.0Me/see bychanging theloading ofone oftheinter- * stage timed circuits. 
 RESONANT -ANY PAPERS HAVE BEEN WRITTEN TO DESCRIBE THE EVOLUTION OF THIS THEORY FOR A COMPLETE SUMMARY  THE READER IS REFERRED TO &UNGS DEVELOPMENT  /THER -ODELS  4HE THEORY FOR VOLUME SCATTER HAS LED TO MANY PAPERS AND CON 
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 47. J. W. 
 NOISE POWER RATIO   *.2 0*N S IN %Q    ( STANDS FOR THE COM 
 themodulated pulse,whichisproportional to(sinnBt}/nBt. 15Thepeakpowerofthepulseis increased bythepulsecompression ratioBTafterpassagethrough thefilter. TheFMwaveform intheblockdiagram ofFig.11.14isgenerated bydirectlymodulating thehigh-power transmitter. 
 An advantage of the parallel-line configuration is that the signal passes through  but two switches and, in principle, sliould have a lower insertion loss than the cascaded  digitally swltclied phase sliifter described below. A disadvantage is the relatively large number  One-by-N switch  Figure 8.5 Digitally switched parallel-line phase shifter with N switchable lines.  TilEFU:CTRONICAI.I.Y STEERED PHASED ARRAY ANTENNA INRADAR287 Thevarious phaseshifting lechniquespossess lheseproperties invarying degree. 
 SIDEBAND  SIGNALS TO ADD AT ONE OUTPUT PORT AND TO SUBTRACT AT THE OTHER 7HERE WIDE BANDWIDTHS ARE INVOLVED  THE )& HYBRID IS OF THE ALL 
 2016 ,54, 1062–1073. [ CrossRef ] 7. Wang, B.; Xu, S.; Wu, W.; Hu, P .; Chem, Z. 
 PENDENT OF RANGE FOR A CONSTANT ALTITUDE TARGET  )T HAS THE POTENTIAL OF RESTORING MUCH  OF THE FRAME TIME AND RANGE PERFORMANCE  BUT INCURS INCREASED SIDELOBE CLUTTER LEVELS AND INCREASED TRANSMITTER COST AND COMPLEXITY !N EXAMPLE IS GIVEN IN 7ILLIS  .ONCOOPERATIVE 2& %NVIRONMENT  -OST PASSIVE BISTATIC RADAR 0"2  CONCEPTS  AND DEVELOPMENTS EXPLOIT COMMERCIAL BROADCAST TRANSMITTERS AS THEIR SOURCE OF RADAR ILLUMINATION &- AND (IGH $EFINITION ($  46 TERRESTRIAL BROADCAST TRANSMITTERS ARE PARTICULARLY ATTRACTIVE DUE TO THEIR HIGH 
 Carter: Provision of Moving Target Indication in an Inde- pendent Bistatic Radar Receiver, Radio Electron. Eng., vol. 54, pp. 
 € Tges=T1+T2 G1+T3 G1G2++TN G1G2Gn−1 (6.10)  Here it is assumed that the respective entrance reflection factors are negligible.       € T1=TAntT2=TaT3=TRFT4=TE G1=1G2=1/LaG3=1/LRFG4=V  With the identifiers from Figure 6.6 the following is obtained:     € Ttotal=TAnt+Ta+TRFLa+TELRFLa (6.11)  The noise bandwidth  € BN for white noise is not identical to the 3 dB bandwidth of the in - between frequency filters (IF bandwidth)  € BIF.  It can be calculated from,   . 
 20.1) versus virtual height and time- of-day at a mid-latitude location. * Typically, the diurnal variation requires a radar to  vary its operating frequency by more than an octave in frequency to maintain 24-hour  surveillance over a fixed target location. *  Virtual height is the reflection height computed from signal time delay by assuming that the radiowave travels at  the speed of light as if in free space; in fact, the radiowave group velocity in the plasma is lower, so the true height  is less. 
 Equation (14.12) becomes  Sw C -<----­<\, -4v cos 1/J (14.13)  Equation 14.l lh would also be modified accordingly. The condition given by Eq. (14.13), and  similar relations, represent an upper bound on the capabilities of an SAR to achieve a resolu­ tion ,\, over a swath S,... 
 There is an amusing story told that on first being given  an aircraft with experimental H2S a navigator returned,  _and, asked for his opinion on the new device, cautiously  and conservatively preferred his former means of navi-  gation, and compared the new one to the H2S (hydrogen  disulphide) of our schoolboy ‘chem’-lab days, saying  _ bluntly, “It stinks!’ But in point of fact H2S was one  of the very few radar devices which were reasonably  . THE MAGIC EYE 139  successful from their inception, and navigators did,  indeed, welcome this new aid with enthusiasm and with  complete lack of odious, odorous comparison.  In H2S the aerial system is placed inside a turret or  streamlined Perspex ‘blister’ under the belly, and  pointing in a directional sense towards the ground. 
 F i I 1FIQ.9.20.—Back view ofpartofAN/APQ-7 scanner, showing toggles. The fixed aluminum channel, which measures about 2%in.by~in. by16ftover all,isfirst extruded, after which the critical surfaces are machined. 
 I., et al.: Side-Looking Radar of Kosmos-1500 Satellite, Issled. Zemli Kosmosa, no. 3, May-June 1985. 
 Data stabilization is  usually used with pencil-beam tracking antennas. A computer can readily calculate the angu­ lar corrections to the output data to account for platform tilt.  An example of the data stabilization is the correction applied for yaw. 
 Using the vertical antennas the range was cut by a half on this beacon, which wasradiating a 15 μs pulse. The minimum range was nominally about 7 –8μs after the end of the transmitter pre-pulse, allowing 2 to 3 μs for the receiver to recover after a Table 6.3. Lucero beacon detection ranges. 
 (16) inclifferential form ~=4RkTdf.Where afinite bandwidth isimplied, itwillsuffice forourpurposes inthischapter tosuppose thatthevoltmeter oramplifier inquestion hasarectangular passband ofwidth @cps.. 30 THERADAR EQUATION [SEC. 28 Another description that isoften useful involves thenotion of“avail- able power. 
 SPACE-BASED REMOTE SENSING RADARS  18.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 polar ice sheets requires that the altimeter have robust range and spatial resolution,  accuracy, and precision regardless of the non-zero average surface slope in both the  along-track and cross-track direction of the continental glaciers. Suitable orbits for  ice sheet missions must have near-polar inclination and multiyear relative accuracy  of a few centimeters. Whereas the methodology of these instruments is to determine the distance between  the radar and the surface, like any radar, an altimeter actually measures round-trip  delay, not distance. 
 The received echo signal at a frequencyf, 4.fd enters the radar via the antenna and 1s  heterodyned in the detector (mixer) with a portion of the transmitter signal fo to producc a  doppler beat note of frequency fd. The sign of.& is lost in this process.  Frequency fo  I\ G  Figure 3.2 (0) Simple CW radar block diagram; (h) response characteristic of bcat-frequency arnpilficr. 
 vol.13, pp.72-82.October. 1974.. 100 1NTHOI)CICTION TO RADAR SYSTEMS  57. 
 BASED WAVEFORM  THE  RELATIONSHIP BETWEEN TIME AND FREQUENCY MODULATION IS GIVEN AS  T 4F "KF" " F " 
 SHAPED SUM PATTERN AND DERIVATIVE OF THE SUM PATTERN . °{ä  2!$!2 (!.$"//+  AS THE MONOPULSE DIFFERENCE PATTERN &IGURE  SHOWS TYPICAL SIDELOBE MULTIPATH  ERRORS FOR HIGHER 
 Notwith- standing itslarge size itdoes not seriously alter the performance ofthe. SEC. 9.25] EXAMPLES OF RADOMES319 aircraft; two additional stabilizers and alarger motor are allthat are necessary tomaintain performance despite the presence ofthis large protuberance. 
 LOSS ELEVATED TRANS 
 QUENCY SWITCHING TIMES AND PHASE SETTLING RESPONSES ARE GENERALLY INADEQUATE TO MEET THE STRINGENT RADAR RECEIVER 
 Thismethod hasbeenapplied byWoodward andDaviestothereception ofsignalsin noise.26-28Itisbasedupontheapplication ofBayes'rulefortheprobability ofcauses.29The jointprobability oftwoeventsxandyis p(x,y)=p(x)p(yIx)=p(y)p(xIy) (10.22) wherep(x)andp(y)=probabilities ofeventsxandy,respectively p(yIx)=conditional probability thateventywilloccur,giventhateventxhas occurred ,,(YI,.)-('nllriirinl1f11 nrnh~hilirv nfpVPllfyvivPIlfhflt,.h~<;n('C-llrrf"O. 378 INTRODUCTION TO RADAR SYSTEMS  Let the event x = SN represent signal-plus-noise, and let the event y be the receiver input,  which may consist of either signal-plus-noise or noise alone. Equation (10.22) may be  rewritten as  This is Bayes' rule. 
 Tile lower the frequency, tile more difficult it is to direct the radar energy at low  a~~glcs ?'his is illustrated it1 Sec. 12.2, wllicl~ gives the elevatio~l angle of the lowest iiiterfere~lce  lobe as A/411,, where A = wavelength and /I, = antenna height. Thus if targets low on the water  are to be seen, higher frequencies may be preferred even if the clutter is greater. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.676x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 To evaluate the effects of oscillator phase noise on MTI performance, there are four  steps. First, determine the single-sideband power spectral density of the phase noise as  a function of frequency from the carrier.38,39 Second, increase this spectral density by  6 dB. 
 Thus, one should choose the nonlinear-phase  filter that uses fewer pulses. Stagger Design Procedures.  The interval between radar pulses may be changed  to modify the target velocities to which the MTI system is blind. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 fewer elements are required. If the triangular lattice contains elements at ( mdx, ndy),  where m + n is even, the grating lobes are located at  cos c os cos c osα αλ α αλxs ys− = ± − = ±x x y ydp dq2 2  where p + q is even.FIGURE 13.10  Grating-lobe positions for ( a) rectangular and ( b) triangular  grids, showing the motion of the lobes as the beam is scanned at angle q0 ch13.indd   18 12/17/07   2:39:41 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 D. Beard, C. I., D. 
 The theoretical rms error of the angle  measurement may be derived in a manner similar to the derivations of time (range) and  frequency errors discussed above. The analogy between the angular error and the time-delay  or frequency error comes about because the Fourier transform describes the relationship  between the radiation pattern and the aperture distribution of an antenna in a manner similar  to the relationship between the time waveform and its frequency spectrum.  For simplicity the angular error in one coordinate plane only will be considered. 
 Since this velocity vector is also  tangent to a hyperbola orthogonal to the range-sum ellipse at this point, all such  hyperbolas become contours of maximum target doppler. ● When d = ± b /2°, the velocity vector is pointed at the transmitter or receiver and  fB = (2V/l) cos2(b /2), which occasionally appears in the literature as a special case  of Eq. 23.9. 
 No losses other than the fluctuation loss have been included in these curves, so that any losses such as range-gate straddle and eclipsing can be accounted for in the computation of R0. The Swerling Case 1 single-scan detection curves can be closely approximated by Pd = p¥j\a+b SNR) (17.25) where Pd = single-scan detection probability PFA = probability of false alarm SNR = signal-to-noise ratio = (R0IR)4 R 9^o FIG. 17.22 Generalized single-scan probability of detection for a scan-to-scan, Swerling Case 1, Rayleigh fluctuating target.CASE abCd eMINIMUM NUMBER OF DETECTIONS REQUIRED 1 31 33NUMBER OF INTEGRATION PERIODSPER DWELL 2 81 53 PROBABI LITY OF DETECTION (%) CASE: . 
 Any use is subject to the Terms of Use as given at the website. Reflector Antennas.  REFLECTOR ANTENNAS  12.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 The magnification m is a useful metric in that it provides a measure of the reduction in  size/length along the focal axis that is enabled by use of the Cassegrain reflector system  in lieu of a single parabolic reflector system. The feed is designed to produce suitable  illumination within subtended angles ±yr associated with the longer focal length fc. 
 Ground Clutter in a Stationary Radar. When the radar is fixed with respect to the ground, both main-beam and sidelobe clutter returns occur at zero- doppler offset, the transmit frequency. The sidelobe clutter is usually small compared with main-beam clutter as long as some part of the main beam strikes the ground. 
 7 .36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 FIGURE 7.29  Bank of parallel radar-tracking filters, each employing a different target motion model   (after S. Blackman and R. Popoli44 © Artech House 1999 ) FIGURE 7.30  Flowchart of interacting multiple models ( after S. 
 An echo from a moving target produces a series of pulses  which vary in amplitude according to the doppler frequency. The output of the range gates is  st retched in a circuit called the boxcar generator, or sample-and-hold circuit, whose purpose is  to aid in the filtering and detection process by empliasizing the fundamental of the modulation  frequency and eliminating harmonics of the pulse repetition frequency (Sec. 5.3). 
 Olson: Recognizing Low-Altitude Wind Shear Hazards from Doppler Weather Radar: An Artificial Intelligence Approach, J. Atmos. Ocean. 
 J. W.. Jr. 
 TUBEv DESIGNATION MEANING A VACUUM TUBE  MIGHT NOT ALWAYS APPLY 5NLIKE THE LINE 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°xx  $ # 3CHLEHER  h2ADAR DETECTION IN LOG 
 If very low sidelobes are specified in nonprincipal planes, it may be  necessary to maintain square corners, as shown in the upper part of Figure 12.17 e. Parabolic-Cylinder Antenna.18,19 It  is quite common that either the beam must  be steerable or shaped in only one plane,  either azimuth or elevation. A parabolic  cylindrical reflector fed by a linear array  feed can accomplish this at moderately  higher cost. 
 Amplifiers are designated  as operating either Class-A, -B, -AB, -C, -D, -E, -F, or -G. Class-A, -AB, -B, and  -C generally refer to analog amplifiers whereas Class-D, -E, -F, and -G generally  refer to switching-mode amplifiers. Each class of operation for the analog modes  is defined by the manner in which the transistor is biased; each class of operation  FIGURE 11.13  Solid-state power amplifier module combines many single stage amplifiers together with  matched phase and amplitude using resistively isolating combining techniques ch11.indd   18 12/17/07   2:25:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 This is equivalent to looking at an infinite array from free space at a scan angle given by Eq. (7.26). A matching structure, designed from the sim- ulator impedance data, may be placed into the simulator to measure its effective- ness. 
 Therefore, as one would expect, the affects candiffer widely. The further the radar wave and returning echo must travelthrough this medium then the greater will be the attenuation and subsequentdecrease in detection range. This is the case whether the target is in oroutside the precipitation. 
 It quickly reports a target’s  change in heading or course, including rate of turn data, if it is available on the target  vessel. AIS is not affected by sea clutter and can report absolute position accurately—to  normally better than 10 meters or even a meter or two, if reporting differential GNSS- derived positional data. However, AIS relies on cooperative targets; is prone to gross  errors in data accuracy, mainly caused by setup errors; and totally relies on reasonably  accurate GNSS data being available. 
 380 INTRODUCTION TO RADAR SYSTEMS  Ideal observer. The criterion of Neyman-Pearson is nol the only one which might be uscJ for  establishing a threshold level. One of the first mathematical criteria applied to the theory of  radar detection was the Idea Observer ·as formulated by Siegert. 
 2.27  Antenna Noise Temperature  ..............................  2.28  Transmission-Line Noise Temperature  ...............  2.30 Receiver Noise Temperature  ............................. 
 CENTERED +ALMAN FILTER CAN WORK WELL BUT MAY HAVE DIFFICULTY ACCOMMODATING RADAR MEASURE 
 ENDED WAVEGUIDE OR A SLOT MIGHT BE CONVENIENT !T THE LOWER FREQUENCIES  WHERE COAXIAL COMPONENTS ARE PREVALENT  DIPOLES HAVE BEEN FAVORED ! GROUND PLANE IS USUALLY PLACED ABOUT  K  BEHIND AN ARRAY  OF PARALLEL DIPOLES SO THAT THE ANTENNA FORMS A BEAM IN ONLY ONE HEMISPHERE &OR LIMITED SCANNING SAY  LESS THAN  n   IT IS POSSIBLE TO USE DIRECTIVE RADIATORS  HAVING DIMENSIONS OF HEIGHT AND WIDTH OF SEVERAL WAVELENGTHS 7 ITH SUCH SEPARATION   THE MUTUAL COUPLING EFFECTS SEE 3ECTION   CAN BE SMALL  AND THE PATTERN AND IMPED 
 It was one of the first practical examples of electronic scanning  and has been widely employed. It is discussed separately in the next section. One of the more  popular forms of phase shifters is one that varies the physical length of line to obtain a change  in phase, especially when the lengths of line are quantized digitally. 
 In order to obtain an exact computation of the array radiation pattern, the pattern of each  element must be measured in the presence of all the others. The array pattern may be found by  suniming the contributions of each element, taking into account the proper amplitude and  phase.  In a two-dimensional, rectangular planar array, the radiation pattern may sometimes be  written as the product of the radiation patterns in the two planes which contain the principal  axes of the antenna. 
 19. Logue, S. H.: Rate-of-climb Meter Uses Doppler Radar, Electronics, vol. 
 LAID ON THIS HARDWARE AND SOFTWARE INFRASTRUCTURE ! SPECIFIC MODE IS IMPLEMENTED IN AN APPLICATIONS PROGRAM IN THE SAME SENSE THAT WORD 
 !  AND %7 FUNCTIONS ADAPTED    . 
  
 Inmany cases, the equipment should have provisions forinstantaneous ydetermining ina precise numerical way the exact position ofeach target with respect to the radar setortoother targets, and often itshould furnish means for passing these results onto other devices inanautomatic way. Allofthis must bedone insuch amanner that theecho signals have optimum sen- sitivity compared tointernal system noise and toextraneous radiations. The accomplishment ofthese objectives requires aconsiderable array ofequipment. 
 STITUTING THE APPROPRIATE VALUE OF  R F INTO %QS  TO  "Y LETTING  RF   RVK   WHERE RV IS THE RMS VELOCITY SPREAD OF THE CLUTTER  THE LIMITATION ON  ) CAN BE PLOTTED  FOR DIFFERENT TYPES OF CLUTTER AS A FUNCTION OF THE WAVELENGTH  K AND THE PULSE REPETITION  FREQUENCY  FR 4HIS IS DONE FOR ONE 
 2005 ,43, 2325–2331. [ CrossRef ] 17. Rankine, W.J.M. 
 14.15 . This page has been reformatted by Knovel to provide easier navigation. Contents     xxi   IF Amplifier  ........................................................ 
 FORMANCE ESTIMATION )T DOES NOT EMPLOY FULL $ RAY 
 38,  pp. 771-774, July, 1950.  12. 
 II, vol. 24, pp. 46–156, 1945. 
 aperture overlap but at the price of loss of angle sensitivity and antenna gain. Monopulse Tracking with Phased Arrays. In general, phased-array tracking radars fall in either the amplitude- or the phase-comparison class, depending on the feed technique. 
 FREQUENCYv PULSES  EACH WITH A FREQUENCY SOMEWHAT GREATER THAN THAT OF THE PREVIOUS PULSE "Y A hSINGLE 
 SOURCE   SHOWN AS A 'A!S  0(%-4 &%4 IN CROSS 
 T. Blackband (ed.):Gordon arid !jreacti,  New York. 1966. 
 E. Rittenback: Continuous-Wave Radar with High Range Resolu-  tion and Unambiguous Velocity Determination, IRE Trans., vol. MIL-6, pp. 
 c.Rectangular plots ofrange and angle. B.Rectangular plots ofazimuth and elevation. 1.True displays which follow theantenna orientation. 
   PP n  *ANUARY  AND REPRINTED IN $ + "ARTON   #7 AND $OPPLER 2ADARS   3ECTION 6) 
 As a Class-C-biased transistor is pulsed, it passes through its cutoff, linear, and saturation regions. Consequently, the input and output impedances are dynamically varying, and the input impedance changes most dramatically. The input impedance match may change from a near- infinite VSWR in the OFF state to a well-matched condition in the ON state. 
 Additional feeds displaced from the focal point form additional beams at angles from the axis. This is a powerful capability of the reflector antenna to provide extended coverage with a modest increase in hardware. Each additional beam can have nearly full gain, and adjacent beams can be compared with each other to interpolate angle. 
 Moreover, these ferrite devices are  nonlinear devices and can generate harmonics. Spurious doppler spectra are created by any process that does not reoccur identi - cally on each transmitted pulse. Gaseous receiver-protectors ionize under transmitter  power levels, but there is some small statistical variation in the initiation of ioniza - tion on the leading edge of the pulse and in its subsequent development. 
 29.  pp. 1358 -1368. 
 AES-5, pp. 632–637, July 1969. 52. 
 Just as the range-azimuth coordinates of a target can be obtained  with a vertical fan-beam antenna, the elevation coordinate can be obtained with a horizontal  fan beam. (The three coordinates can thus be obtained with two 2D-radars.) Such a height  finder would be directed by the 2D air-surveillance radar to the azimuth of the target. It then  OTHER RADAR TOPICS541 receivers alsoreduceweather clutterattheradaroutput.However, inair-traffic-control opera­ tions,itisimportant thatthecontroller knowthelocations ofthebadwe~theJ soasnotto vectoraircraftthrough it.IntheARSR-3, theweather information isavailable attheortho­ gonalportofthecircular-polarization diplexcr andcanbeviewedbyswitching thisoutputto thcdisplay. 
 The horizontal aperture of the antenna determines the finest azimuth resolution achievable in a single-beam synthetic aperture radar except for the searchlight mode. Moreover, in the signal processing it is assumed that the antenna gain is constant as a function of along-track position. Thus, it is necessary to have a degree of stabilization of antenna pointing so that the beam . 
 The  function of the diode is to hold the maximum voltage and keep the delay line from discharging  until the thyratron is triggered.26 Although the series diode is a convenient method for varying  the prf, it is ,. more difficult to change the pulse width since high-voltage switches in the  pulse-forming network are required.  The bypass diode and the inductance LB connected in parallel with the thyratron serve to  dissipate any charge remaining in the capacitance due to tube mismatch. 
 PULSE 2ULE  /PERATE AT CONSTANT DUTY CYCLE 4HE TRANSMITTER WHETHER THE TRANSMITTER  IS A SINGLE LARGE TUBE OR A DISTRIBUTED FUNCTION AS IN AN ACTIVE PHASED ARRAY WITH MANY  TRANSMIT 
 290-303, 1958.  79. Schneider, A. 
 7.2. The same illumination functions  used in antenna design to reduce spatial sidelobes can also be applied to the frequency domain  to reduce the time sidelobes in pulse compression. A comparison of several types of spectra I  weighting functions is shown in Table 11.1. 
 A claim was made that a particular GPR and its operator  could detect targets the size of golf balls at a depth of eight meters. Clearly, the  wavelengths capable of propagating to eight meters in soil would be so much larger  than a golf ball–sized target that the radar cross-sectional area of the latter would  fade into insignificance, even noise. The persuasiveness of the claimant and the lack  of understanding of basic physics on the part of some potential users enabled this  kind of claim to be seriously considered. 
 125. U. Nickel, “Aspects of implementing superresolution methods into phased array radar,” Int. 
 TION TO BE PERFORMED MUCH MORE QUICKLY  ALLOWING MORE TIME TO DO OTHER THINGS /F COURSE  IN ORDER TO FORM MULTIPLE SIMULTANEOUS RECEIVE BEAMS  THE TRANSMITTED BEAM MUST BE MADE BROADER TO ENCOMPASS THE RECEIVE BEAMS  WHICH MIGHT REQUIRE A MORE POWERFUL TRANSMITTER OR MORE INTEGRATION ON RECEIVE TO PROVIDE THE SAME PERFORMANCE AS A SINGLE 
 The unloaded Qofthecavity islower than that ofacylinder because of FromT-iunctionFlexible \nd,aphragm I~ \RetainingrmgI @,Isol,,,,Oit . \1~dtam.flange /Keep-alweTomixer electrcdeterm,nals I 1“dlam.flange FIG.11.15.—1B27 TRtube andcavity assembly withloop coupling, the presence ofthe cones and the glass ofthe gasenclosure; itisabout 2000. With normal input and output loading, theloaded Qisabout 35o. 
 ch01.indd   2 11/30/07   4:33:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 
 4.lb is not necessarily the most typical. The block  diagram of a more common MTI radar employing a power amplifier is shown in Fig. 4.5. 
 no. 2, pp. 36-45, 1975. 
 [lwcll: Cliaractcristics of Snow at Millimetcr Wavclcngtlls. 1976  Il.;I:E rrrc~rrrrc~s trrrd I'r~olrcrqc~tiorr Soc.iclry Syrrtposi~rrtr, Oct. 11 15, 1976, pp. 
 4INTRODUCTION TORADAR SYSTEMS Themeasure oftheamountofincident powerintercepted bythetargetandreradiated backin thedirection oftheradarisdenoted astheradarcrosssection (J,andisdefinedbytherelation Powerdensityofechosignalatradar=P,G2~4rrR4n:R(1.5) Theradarcrosssection (Jhasunitsofarea.Itisacharacteristic oftheparticular targetandisa measure ofitssizeasseenbytheradar.Theradarantenna captures aportionoftheecho power.Iftheeffective areaofthereceiving antenna isdenoted A",thepowerP,received bythe radaris (1.6) Themaximum radarrangeRmaxisthedistance beyondwhichthetargetcannotbedetected.It occurswhenthereceived echosignalpowerP,justequalstheminimum detectable signalSmin' Therefore [PGA(J]1/4 Rmax=(4~)2S:in(1.7) Thisisthefundamental formoftheradarequation. Notethattheimportant antenna par~ ametersarethetransmitting gainandthereceiving effective area. Antenna theorygivestherelationship between thetransmitting gainandthereceiving effective areaofanantenna as (1.8) Sinceradarsgenerally usethesameantennaforbothtransmission andreception, Eq.(1.8)can besubstituted intoEq.(1.7),'firstforAethenforG,togivetwootherformsoftheradar equation Rmax=[PIG:A2 (Jr/4 (1.9)(4n:)Smin Rmax=[P,A;O']1/4(1.10) 4rrA.2Smln Thesethreeforms(Eqs.·1.7, 1.9,and1.10)illustrate theneedtobecarefulintheinter­ pretation oftheradarequation. 
 SEC. 1615] THE STABLE LOCAL OSCILLATOR 659 when amplitude modulation isavoided. Information onthis point isnut available fortheother types. 
 BAND LONG 
 RANGE LINEAR RECEIVE AMPLIFIERS ARE BIASED #LASS 
 N From Byron Edde, Radar: Principles, Technology,  Applications , Prentice-Hall. 31Dwell Time HALF POWER  ANGLE HPBW ...MAXIMUM  VALUE OF   GAINANTENNA POWER  PATTERN (POLAR PLOT) BθDB /λ θ≈• Simple antenna model: constant gain  inside the half power beamwidth (HPBW), zero outside.  If the aperture has a diameter D with uniform  illumination                 . 
 Itwasalsousedinthepasttoprobethemoonandthe planets(radarastronomy). Theionospheric sounder, animportant adjunctforHF(short wave)communications, isaradar.Remote sensing withradarisalsoconcerned with Earthresources, whichincludes themeasurement andmapping ofseaconditions, water resources, icecover,agriculture, forestryconditions, geological formations, andenviron­ mentalpollution. Theplatforms forsuchradarsincludesatelJites asweBasaircraft. 
 A comparison of the electron density proﬁle of the ISR and the modiﬁed topside proﬁle of ionosonde validated our algorithm. The outline of this paper is given as follows: Section 2presents the method of TEC retrieval from PolSAR and the method for improving the topside proﬁle model of ionosonde with the known TEC. Then, details of data used in this paper are introduced in Section 3. 
 .,5. Lohcnstcin, H .. and D. 
 12.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 This nomograph6 is frequently used for the simple configurations in Figure 12.8 a. For  other configurations and thread forms, the same equation can be used by computing  an equivalent radius by matching the cross sectional areas. One significant source of radiation in the back hemisphere is leakage through  the reflector. 
 13.) p(<r)==e-°ll} (2.23)(T where a is the average cross section. (This is a negative-exponential density func- tion, but a target having this distribution is called a Rayleigh target because this distribution of a produces a received signal voltage which is Rayleigh- distributed.) The second assumed cross-section density function is P(a) = ^ e~2^ (2.24) The first distribution, Eq. (2.23), is observed when the target consists of many independent scattering elements of which no single one or few predominate. 
 10. Sammartino, P .F.; Tarchi, D.; Oliveri, F. GB-SAR and MIMO radars: Alternative ways of forming a synthetic aperture. 
 29. Imbriale, W. A., P. 
 The procedure was tested by processing TerraSAR-X high-resolution images. Results were compared with outcomes coming from other classiﬁcation methods, showing improved performances. Spaceborne SAR observations are very promising for identifying and studying the mechanism governing oceanic eddies. 
 Since thetransmitter starts with random phase from pulse topulse, itisnecessary tomatch thephase oftherefer- ence oscillator tothat ofthe transmitter ateach transmitted pulse. 1(,second time around ~)echoes—signals received from thesecond preceding pulse-will not becanceled bythe arrangement ofFig. 166.. 
 LINE POLES   SEA  ICE  ICEBERGS  BUOYS  UNDERGROUND FEATURES  METEORS  AURORA  SPACECRAFT  AND PLANETS )N ADDITION TO MEASURING THE RANGE TO A TARGET AS WELL AS ITS ANGULAR DIREC 
 5.12 two antennas are shown separated by a distanced. The distance to the target  is R and is assumed large compared with the antenna separation d. The line of sight to the  Antenna  No.I___.., Target  Figure 5.12 Wavefront phase relationships in phase­ comparison monopulse radar. 
 Conrp.. vol. 19, pp. 
 The crossed electric  and magnetic fields cause the electrons to be completely bunched almost as soon as they are  emitted from the cathode. After becoming bunched, the electrons move along in a traveling­ wave field. This traveling-wave field moves at almost the same speed as the electrons, causing  RF power to be delivered to the wave. 
 amperes during theearly part ofitsexponential rise. Ifthis current is nottoexceed afew percent ofthedesired load current forpulse lengths around 1psec, L,must have avalue between 10and 20mh. With this information, the number ofturns inthe primary and the required core area canbeobtained from tables showing theeffective permeability ofthe core attheflux densities and rates ofrise anticipated. 
 9.5 to 9.7. The circulator does not provide  sufficient protectiorl by itself and requires a receiver protector as in Fig. 9.9. 
 The function of the  radar display is to aid the operator to extract in an efficient manner the information contained  in the radar signal that is important to the task. The usual type of radar display is a cathode­ ray tube or its equivalent.  The ability of the operator to detect radar signals in the presence of noise or clutter  cannot be determined with as great a reliability as can the performance of the electronic  threshold detector described in Chap. 
 SURE TARGET ALTITUDE 7HEN THE SITES SURROUND THE TARGET  FOR EXAMPLE  WHEN POSITIONED  AROUND THE LAUNCH SITE OF A BALLISTIC MISSILE   @ REMAINS RELATIVELY LARGE DURING THE  MISSILES LAUNCH PHASE  YIELDING PRECISE ALTITUDE ESTIMATES 7HEN THE SITES ARE SOME  DISTANCE FROM THE TARGET  FOR EXAMPLE  WHEN CONDUCTING AIR OR MISSILE SURVEILLANCE   @  IS  SMALL  YIELDING POOR ALTITUDE ESTIMATES "OTH BISTATIC AND MULTISTATIC RADARS CAN POTENTIALLY ACHIEVE EVEN BETTER LOCATION  ACCURACY BY USING NARROW 
 I-.: Random Errors in Aperture Distributions, IRE Trans., vol. AP-7, pp. 369-372,  Octohcr. 
 Thus the various mathematical  models cannot, in general, be expected to yield precise predictions of system performance.  It has been s~ggested~'.~~ that if only one parameter is to be used to describe a complex  target, it should be the median value of the cross section with Rayleigh statistics (Swerling  cases 1 and 2). Quite often Swerling case 1 is specified for describing radar performance since it  results in conservative values. 
 PARED WITH THE NUMBER OF JAMMING SIGNALS   !PERTURE 
 III, chap. 13. 71. 
 Performance of theFIG. 22.2 SBR coverage and nadir hole. 2ire/X RMS PHASE ERROR (rad) FIG. 
 Richards (ed.), Van Nostrand Reinhold Co., New 'i'ork.  1969.  104. 
 We also compare our results with those of the following studies (Table 2). T able 2. Summary of the previous studies of land subsidence in Wuhan city. 
 In effect, this creates an apparent change of target direction as viewed from the  radar. A large repeater gain is required to generate a high jammer-to-signal ratio; oth - erwise, the skin echo will overwhelm the jamming signals in the interferometer pattern  nulls. The maximum effectiveness of the technique implies a considerable delay (on  the order of 100 ns) in the repeated signal, owing to the transmission line and amplifier  between the receiver and transmitter antennas. 
 HORN TRIPLE 
 133, pt. F, pp. 604-612, December 1986. 
   PP n      $ , %VANS  7 !LPERS  ! #AZENAVE  # %LACHI  4 &ARR  $ 'LACKIN  " (OLT  , *ONES  7 4 ,IU    7 -C#ANDLESS  9 -ENARD  2 -OORE  AND % .JOKU  h3EASATn!  
 CARPET is programmed in C ++ and has a Windows XP-compatible user-friendly  graphical interface. †  Actually, it is a generalized Blake chart (that improves on the original Blake chart), which includes details such as  antenna patterns, processing, system losses, etc., in a suitable electronic format.ACRONYM LIST ADC Analogue-to-Digital Converter ADT Automatic Detection and Tracking AF Ambiguity Function AFS Automatic Frequency Selection AGC Automatic Gain Control AMF Adaptive Matched Filter API Application Programming Interface A-RGPO Anti Range Gate Pull Off ARM Anti Radiation Missile A-SOJ Anti-Stand Off Jammer ch24.indd   56 12/19/07   6:01:15 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 If wide-angle scan is not required, the open-  ended waveguides may be flared to form a horn with greater directivity. An array of open-  ended waveguides quite often will be covered with a thin, flat sheet of dielectric to serve as a  means for better matching the array to free space, as well as to act as a radome to protect the  array from the weather.  Other radiators that have been used in phased arrays include microstrip antennas,160  polyrods, helices, spirals, and log-periodic elements. 
 Navy Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS),” Naval  Research Laboratory, Marine Meteorology Division, NRL Publication 7500-03-448, May 2003. 27. Naval Research Laboratory, Washington, DC, https://simdis.nrl.navy.mil, simdis@enews.nrl   .navy.mil. 
 bandwidth ofeachindividual filteriswideenough toacceptthesignalenergy, but notsowideastointroduce morenoisethanneedbe.Thecenterfrequencies ofthefiltersare staggered tocovertheentirerangeofdoppler frequencies. Ifthefiltersarespacedwiththeir half-power pointsoverlapped. themaximum reduction insignal-to-noise ratioofasignal whichliesmidway between adjacent channels compared withthesignal-to-noise ratioat 1idband is3dB.Themorefiltersusedtocovertheband,thelesswillbethemaximum loss experienced. 
 Madsen, H. Zebker, and J. Martin, “Topographic mapping using radar interferometry,” IEEE  Trans Geoscience and Remote Sensing , vol. 
 Thus the AGC will not regulate weak signals. The effect is similar to having a  delay voltage, but the performance will not be as good.  The required dynamic range of the AGC will depend upon the variation in range over  which targets are tracked and the variations expected in the target cross section. 
 £Î°£È  2!$!2 (!.$"//+  TO THE DIRECTION OF SCAN  !S THE BEAM IS SCANNED  EVERY POINT ON THE PLOT  IS TRANSLATED IN  THE SAME DIRECTION AND BY THE SAME DISTANCE AS IS THE BEAM MAXIMUM 4HE REGION INSIDE THE UNIT CIRCLE WHERE   COS COS AAXY a &)'52%  0LANAR 
 TheMRA5operates withinthe10to10.5GHzband,from100mto 50kmrangewithanaccuracy of±0.05m±10-5d,assuming acorrection ismadefor meteorological conditions. Inaddition toitsuseinsurveying, themultipleCWfrequency methodofmeasuring range hasbeenappliedinrange-instrumentation radarforthemeasurement ofthedistance toa transponder-equipped missile;65 thedistance tosatellites;66 insatellitenavigation systems basedonrangemeasurement;67 andfordetecting thepresence ofanobstacle inthepathofa movingautomobile bymeasuring thedistance, thedoppler velocity, andthesignofthe doppler(whether thetargetisapproaching orreceding).63 REFERENCES 1.Sandretto, P.c.:TheLongQuest,IRETrans.,vol.ANE-l,no.2,p.2,June,1954. 2.VanVleck,J.H.,andD.Middleton: ATheoretical Comparison oftheVisual,Aural,andMeter Reception ofPulsedSignalsinthePresence ofNoise,J.Appl.Phys.,vol.17,pp.940-971, November, 1946. 
 Bulk-effect and avalanche diodes. The Gunn and LSA bulk-effect diodes and the Trapatt and  lmpatt al'ala11che diodes can be operated as oscillators or single-port negative-resistance  amplifiers.29·45 They have been considered for use at the higher microwave frequencies where  the transistor amplifier has reduced capability, but they can also operate at L band or below.  Unfortunately, the peak and average powers of such devices are low, as is the erficiency and the  gain. 
 value of the aperturedistribution is equal to A, and if the phase distribution across the aperture  is constant, the antenna pattern as computed from Eq. (7.10) is  - /to sin [n(n/A) sill $1 - - . - -. 
 It is also  possible to employ the more usual frequency-domain bandpass filters of conventional design  in MTI radar to sort the doppler-frequency-shifted targets. The filter configuration must be  more complex, however, than the single, narrow-bandpass filter. A narrowband filter with a  passband designed to pass the doppler frequency components of moving targets will "ring"  when excited by the usual short radar pulse. 
 Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation. 26.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 played in the United States. It was attended by over 60,000 people, all confined in  one sporting event stadium, which presented a significant target for a terrorism attack. 
 Conventional CFAs have higher noise levels than linear-beam tubes, and their signal-to-noise ratio is typically only 55 dB in a 1-MHz bandwidth; the low-noise CFA, however, can be 70 dB or better (Sec. 4.4). Leveling. 
  
 51. C. Kopp, “Missiles in the Asia-Pacific,” Defence Today , http://www.ausairpower.net/   DT-Missile-Survey-May-05.pdf. 
 29.Blacksmith, P.,Jr.,R.E.Hiatt,andR.B.Mack:Introduction toRadarCross-Section Measurements, Proc.IEEE,vol.53,pp.901-920, August,1965. 30.Olin,I.D.,andF.D.Queen:Dynamic Measurement ofRadarCrossSections, Proc.IEEE,vol.53, pp.954-961, August, 1965. 31.Skolnik, M.I.:AnEmpirical Formula fortheRadarCrossSectionofShipsatGrazing Incidence, IEEETrans.,vol.AES-lO, p.292,March,1974. 
 FIGURE  2.15 Clutter power in two-sided tails of spectrum vs. multiple of standard deviation ch02.indd   16 12/20/07   1:43:42 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 CLUTTER RATIO  BUT IT WILL ALSO REMOVE WEAK AND FAST 
 The precision oftriggering usually isabout +0.2psec, unless special precautions aretaken toinsure correct trigger wave shape and amplitude. The most versatile switch isthenewly developed hydrogen thyratron (Fig. 10”41), which requires apositive trigger ofonly 150 volts rising at the rate of100 volts perpsec. 
 This effect can be expected tobenotable only when the target extent iscomparable toc divided bythe bandwidth. Third, there isaphase change, linear inw, with proportionality constant depending onthe distance. Fourth, all frequencies areshifted bythedoppler frequency. 
 There is,inother words, acontinual evaporation ofwater from the sea 10ne must becareful nottoconfuse thedirectional pattern ofanantenna with theplotofcontours ofconstant intensity inthefield oftheantenna, which itocca- sionally superficially resembles. Ifweplot thegain ofanantenna asafunction of angle, inpolar coordinates, wehave anantenna pattern that hasmeaning, strictly) only iftheantenna isisolated inspace. Ontheother hand, contours ofconstant intensity, thecoordinates ofwhich refer directly tOpOsitiOns insPace, canbeused tO describe theradiation field nomatter what thesurroundings ortype ofpropagation involved. 
 The method ofdoing this hasbeen described inthepreceding section. 16.13. Beating Due toFinite Pulse Packet.—In addition tothe fluctuations due toscanning and wind, there isanother kind offluctuation when thesystem ismoving. 
 0ENETRATION &/0%.  3!2  !LTHOUGH HIGHER FREQUENCY GREATER THAN  APPROXIMATELY  '(Z  MICROWAVES DO NOT PENETRATE FOLIAGE WELL   LOWER FREQUENCY MICRO 
 If the maximum radar range, Rmax, is defined as occurring when the received signal is  equal to the minimum detectable signal of the radar, Smin, the simple form of the radar  equation becomes  RP G A St t e max min4 24=σ π( ) (1.3) Generally, most radars use the same antenna for both transmitting and receiving. From  antenna theory, there is a relation between the gain Gt of the antenna on transmit and  its effective area Ae on receive, which is G At e=42π λ/, where l is the wavelength of  the radar signal. Substituting this into Eq. 
 Based on the spatial continuity assumption, the predicted forward and backward echo information is colored in red, while the initial echo pulse in blue. Detailed pulse information prediction method will be introduced in the Section 3.2, and the prediction factor is set as 0.5 in the experiment. Because the forward and backward pulse lengths are half of the length of one CPI, the equivalent CPI length (i.e., about 0.1 s) in the newly merged signal is doubled than the original CPI length (i.e., about 0.05 s) as shown in Figure 3b. 
 The circuit is shown in Fig. 2. This  circuit is given, as it is typical of those in which the  saw-tooth is produced from a rapid charge and a slow  . 
 Even so, the exact evalu - ation for the cylinder includes fictitious contributions from the shadow boundaries at  the sides of the cylinder that do not appear in a stationary phase approximation .30 The amplitude of the elemental surface contributions changes slowly over the surface  of integration whereas the phase changes much more rapidly. As such, the net contribu - tion in regions of rapid phase change is essentially zero and may be ignored. As the spec - ular regions are approached, on the other hand, the phase variation slows down and then  reverses as the specular point is crossed. 
 Ahsolute rangeaccuracy--IO to20kIll,assuming real-time analysis ofthepropagation pathis made. A/lgleresoll/tio/l determined bythebeamwidth; itcanbelessthan10whichcorresponds to 50kmatadistance of3000km. A/I~/l('llCnlrllCY "beamsplitting" ofonepartin10shouldbepossible ifthesignal-to-noise ratioissuffkient; ionospheric effectsmightlimittheanglemeasurement accuracy tosome fraction ofadegree. 
 2.5 to 2.7, these additional factors will be discussed. The quantities Pr,min, (S/N)min9 and D0 are all related, as indicated in the de- velopment of Eqs. (2.3) to (2.9). 
 time constant video ﬁlter (the clutter ﬁlter discussed in chapters 3and4), instanta- neous automatic gain control, swept gain and offset expanded sector scan. For fully submerged submarines, the use of sonobuoys was only just starting to be developed [ 1,6] and some limited success had also been achieved with magnetic anomaly detectors (MAD) [ 1]. 8.3 Coastal Command at the end of WWII On 1 April 1945, the Coastal Command battle line comprised 40 RAF squadrons, two FAA, one SAAF and six USN, representing a total establishment of 765aircraft, of which 481 were available for operations [ 5]. 
 sets ofvideo signals oneach oftwo carriers. One channel isshared between theMTI video signals and the lower-beam video signals, MTI video being trans- mitted foratime interval corresponding tothe first 30to50miles of range from theradar, and thelower-beam video fortheremainder ofthe radar cycle. Asecond channel isshared between theupper-beam radar echoes and thebeacon signals; since the data from these two aresimul- taneous, switching must bedone onawhole-cycle, rather than onafrac- tional-cycle, basis. 
 Forexample, itwouldbenecessary tospecifytheapriori probability offindingatargetatanyparticular rangeatanyparticular time.Thisisanalmost impossible task.Intheabsence ofbetterdata.itmightbeassumed thatallrangeintervals are equally probable apriori,andtheaprioriprobability maybeconsidered tobeconstant. However, suchanassumption applied blindlytocomputations involving inverseprobability cansometimes leadtoerroneous andcontradictory conclusions.29Thisdifficulty inspecifying theaprioriprobability wasrecognized byWoodward andDavies.27Theysuggest, however, thattheapriorifactorbeomitted fromtheinverse-probability specification whenitisdoubt­ ful,andinpractice itmaybesupplied subjectively bythehumanobserver. Thismerelybegs thequestion, forithasnotbeenprovedthatanoperator cansupplythenecessary apriori probability, andinaddition, therearemanyapplications wherenooperator isinvolved in making thedetection decision. 
 PHASE AND &)'52%   3ERIES 
 Howard, J. Nessmith, and S. M. 
 Frame B (24 km×24 km) highlights a shear-wave-generated eddy. T able 4. The related parameters of ERS-2 Synthetic Aperture Radar (SAR). 
 Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 12.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 12.3 REFLECTOR ANTENNA ARCHITECTURES Reflector antennas are built in a wide variety of shapes and sizes with a corresponding  variety of feed systems to illuminate the surface(s), each suited to its particular appli - cation. Figure 12.15 illustrates the most common of these reflectors, each of which is  described in some detail in the following subsections. 
 Hansen(ed.).Academic Press,N.Y..1966. 65.Radford. M.F.:Frequency Scanning Aerials,Electronic Engineering. 
 F.: The Study of Radar, "Research Science and Its Application in Indus- try," vol. 6, Butterworth Scientific Publications, London, 1953, pp. 434—440. 
 is relatively massive and heavy because it has four servo systems for controlling  RADAR ANTENNAS 271 berequired evenwithsomeformofmechanically stabilized mounts. Datastabilization is usuallyusedwithpencil-beam tracking antennas. Acomputer canreadilycalculate theangu­ larcorrections totheoutputdatatoaccount forplatform tilt. 
 IZABLE LESSON IS THAT AN INCREASE IN NUMBER OF LOOKS CAN BE APPLIED TO OFFSET A DECREASE IN RANGE RESOLUTION WITHIN REASON AND IN THIS KIND OF EXPLORATORY SPACE 
 For example, amagnetron operating at20kvand 13.5 amp absorbs power attherate of270 kw, yet adecrease inapplied voltage ofonly 3kvwill drop the current by7amp and virtually stop the oscillation. Since AV/A~ is small, asatisfactory pulser must produce afairly flat-topped pulse free from voltage changes larger than 5percent ofthe peak voltage. The V-1characteristics ofmost magnetrons show irregularities which are associated with various modes ofoscillation whose number, magni- tude, and position vary with magnetron type, r-fload applied tothe Operating point 20—\-------------------- -Modechange 15- 3 ~ % g 910- ~ E %~ 5- Peakplatecurrentinamperes FIG. 
 Radar MeteoroL, pp. 216-221, American Meteoro- logical Society, Boston, 1972. 43. 
 The power pattern and the radiation-intensity pattern are  identical when plotted on a relative basis, that is, when the maximum is normalized to a value  of unity. When plotted on a relative basis both are called the a11te1111a radiation pattern.  An example of an antenna radiation pattern for a paraboloid antenna is shown plotted in  Fig. 
 The  analysis can be extended to include angular errors in both planes, if desired. It is assumed that  the signal-to-noise ratios are large and that the noise can be described by the gaussian  probability-density function.  Consider a linear in-phase receiving antenna of length D, or a rectangular receiving  aperture of width D as shown in Fig. 
 Narrow pulses also  require greater bandwidth to correctly  transmit  and receive. This makes the pulse's spectral nature  also of interest,  which must be considered in the overall  system design  (see Figure 4).    Figure 4. 
 WIDTH OF THE SIDE 
 The derivative, shown dotted inFig. 12.13, has the same shape asthe usual discriminator curve. Inthe scheme shown inthe block diagram, a1000-cycle sine wave from ana-foscillator isadded tothe slowly v’arying voltage from thesawtooth search oscillator. 
 It also assumes that the shape of the  return pulse is not known. If it is, it should be possible with the proper processing to resolve  targets within a pulse width:  When more than one radar, covering approximately the same volume in space, are  located within the vicinity of each other, it is sometimes desirable to combine their outputs to  form a single track file rather than form ~eparate tracks.83•97-s.:1 Such an automatic detection  and integrated tracking system (ADIT) has the advantage of a greater data rate than any single  radar operating independently. The development of a single track file by use of the total  available data from all radars reduces the likelihood of a loss of target detections as might be  caused by antenna lobing, fading, interference, and clutter since integrated processing permits  the favorable weighting of the better data and lesser weighting of the poorer data. 
 The zero-  crossings detector destroys amplitude information. If the exact phase of the echo carrier were  known, it would be possible to design a detector which makes optimum use of both the phase  information and the amplitude information contained in the echo signal. It would perform  more efficiently than a detector which used either amplitude information only or phase infor-  mation only. 
 END SWITCHING CONFIGURATIONS IN A 42 MODULE  IE  BEFORE THE RECEIVE LOW 
 WAY VOLTAGE PATTERN. 
 /- 4HE AUTHORS WISH TO ACKNOWLEDGE AND THANK (ELMUT 3CHRANK  'ARY %VANS  AND $ANIEL $AVIS ALSO CO 
 Mdiraw-Hill Hook Cornpany. New York. 1970. 
 TENTH OF THE RADIUS OF AN ICE  SPHERE OF RADIUS  CM MELTS  SCATTERING OF  
 K. A.: The ( 'alculation of Ground-wave Fick! Intensity over a Finitely Conducting Spherical  Earth. /'me. 
 Finally, the predicted forward and backward pulses are utilized to merge with the initial pulses, then the newly merged pulses in each CPI are utilized to perform the DBS imaging. Since the number of newly merged pulses in KA-DBS is twice larger than that in the conventional DBS algorithm with the same dwell time, the cross-range resolution in the proposed KA-DBS algorithm can be improved by a factor of two. The imaging performance assessment conducted by resorting to real airborne data set, has veriﬁed the e ﬀectiveness of the proposed algorithm. 
 Conf. Oceans-92: Mastering the  Oceans Through Technology, Proc ., vol. 1, October 26–29, 1992, pp. 
 23Range Ambiguities • For convenience we omit the sinusoid al carrier when drawing the pulse  train • When multiple pulses are transmitted  there is the possibility of a range  ambiguity . • To determine the range unambiguously require s that              .  The  unambiguous range is TIME τPoTp TIME TRANSMITTED  PULSE 1TRANSMITTED  PULSE 2TARGET   RETURN TR1TR2 Tp≥2R c Ru=cTp 2=c 2fp. 
 28. 1975.  RADAR ANTENNAS 277 113.Scruton,C,andP.Sachs:WindEffectsonMicrowave Reflectors, "Design andConstruction ofLargeStecrahlcAerials," IEEE(Lolldoll) COII(:PI/Mica/ iOlIno.21,pp.29-38,1966. 
 AES-16, pp. 656-673, September 1980. 26. 
 A typical value of the index of refraction near the  surface of the earth is 1.0003. In a standard atmosphere the index decreases at the rate of about  4 x 10-'m-' ofaltitude. 1 . 
 NING SUFFICES  ANDOR   A VERY HIGH GAIN ELECTRICALLY LARGE  APERTURE IS REQUIRED AND A PHASED ARRAY  IE  AN ELECTRONIC SCANNING ARRAY %3!   IS COST PROHIBITIVE  ANDOR   THE REQUIRED SCAN VOLUME IS LIMITED AND CAN BE SATISFIED VIA USE OF AN ARRAY 
 UNITS PER DECADE .OTE THAT THE &)'52%   3INGLE 
 6.2. 44. G. 
 vol. 94. pl. 
 J. Phys .,  vol. 39, pp. 
 CENTERED TO THE   LEFT OVAL IN &IGURE  D 4HE TYPE OF TRANSMITTER DEDICATED   COOPERATIVE  OR  NON 
 Stabilization of the antenna adds to the weight and size of the radar, but it is necessary in  many applications of radar on ships and aircraft. The requirements for stabilization depend in  part on the nature of the application. Requirements differ whether the radar is used for surface  search, air search, tracking, or height finding. 
 The AGC system detects the  peak voltage of the sum signal and provides a negative dc voltage proportional to the  peak signal voltage. The negative voltage is fed to the IF amplifier stage, where it is  used to decrease gain as the signal increases. A high gain in the AGC loop is equivalent  to dividing the IF output by a factor proportional to its amplitude. 
 BASED SURVEILLANCE -EDIUM DETECTION RANGE ACCURATE RANGE DATA "ATTLEFIELD SURVEILLANCE   SLOW 
 G. Linde, “A simple approximation formula for glint improvement with frequency agility,” IEEE  Trans ., AES-8, pp. 853–855, November 1972. 
   PP n    2 5IJLENHOET  - 3TEINER  AND *! 3MITH  h6ARIABILITY OF RAINDROP SIZE DISTRIBUTIONS IN A SQUALL  LINE AND IMPLICATIONS FOR RADAR RAINFALL ESTIMATION v * (YDROMETEOROL  VOL   PP n    # 2 "URROWS AND 3 3 !TTWOOD   2ADIO 7AVE 0ROPAGATION  #ONSOLIDATED 3UMMARY 4ECHNICAL  2EPORT OF THE #OMMITTEE ON 0ROPAGATION  .$2#  .EW 9ORK !CADEMIC 0RESS    P   7 * (UMPHREYS   0HYSICS OF THE !IR  .EW 9ORK -C'RAW 
 45. Marshall, J. S., and W. 
 HORIZON RADAR v  '%# * 4ECHNOLOGY   VOL    PP n    ' & %ARL AND - * 7HITINGTON  h(& RADAR !$# DYNAMIC RANGE REQUIREMENTS v  RD )NT #ONF ON  !DVANCED !$ AND $! #ONVERSION 4ECHNIQUES   *ULY   ' & %ARL  h&-#7 WAVEFORM GENERATOR REQUIREMENTS FOR IONOSPHERIC OVER 
 The effect ofthese two limitations and the close connection between them can beseen inasimple example. 116. SEC. 
 This rather severe loss was measured under special conditions: low grazing angles  for targets with vertical surfaces, and dihedrals and trihedrals, which generate a large  monostatic RCS. Thus, the bistatic RCS becomes significantly lower as the bistatic  angle increases due to shadowing and loss of these speculars and retro-reflectors.  Bistatic losses should not be as severe for targets with blended surfaces and a less  complex structure, such as combat aircraft. 
 The beam focusing can be provided by a uniform magnetic field generated by a  long solenoid which has iron shielding around the outside diameter. Cooling might have to be  provided for the electromagnets.   he weight of the magnetic focusing system is a major  portion of the total weight of a klystron. 
 § ©¨ ¨¶ ¸· · ` ``  A``¤ ¦¥³ µ´ § ©¨ ¨¶ ¸· ·E   WHERE   @    ATTENUATION FACTOR   A    PHASE CONSTANT AND THE DIMENSIONLESS FACTOR D pD` IS MORE COMMONLY TERMED THE MATERIAL LOSS TANGENT 4HIS DISCUSSION HAS NOT CONSIDERED THE ELECTROMAGNETIC AND MAGNETIC LOSS TANGENT   AND THESE MAY NEED TO BE CONSIDERED IN SPECIAL CASES )T CAN BE SEEN FROM THE ABOVE EXPRESSIONS THAT THE ATTENUATION  CONSTANT OF A MATE 
 Thus,  the entire stream of detections (up to the present) is potentially available to calcu - late the track state used for the association decision on the most recent detection. 2. Track-to-track fusion (see Figure 7.39, lower half) associates each detection to a  single radar track state calculated using only detections from that radar. 
 E.C.T.B.Howard. andG.H.Stevens: PulseCompression. chap.20of"RadarHandbook." M.I.Skolnik (ed.).McGraw-Hili BookCo..NewYork.1970. 
 (Translation available from NTIS, AD 645775,   June 28, 1966.) 21. M. I. 
 H.W..N.P.LUlle.andM.W.Jetrrs:DesignofMTIFilterswithStaggered PRF:A Pole-Zero Approach. Proc.lEE.vol.121.pp.1460--1466. December. 
 7 .54  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 to multisite operation is straightforward. Specifically, if qe1(ti) and qe2(tk) are the DF  angle detections with respect to sites 1 and 2 and if qj1(ti) and qj2(tk) are the esti - mated angular positions of radar track j with respect to sites 1 and 2, then the multisite  squared error is simply  d t tj in e i j i kj = − { }+ = =∑ 11 12 12 11 4 min , [( ) ( )] / θ θ σn n e k j kj t t2 42 22 22∑ − { } min , [ ( ) ( )] / θ θ σ      (7.46) The previously described procedure can then be used, with dj being defined by   Eq. 7.46 instead of Eq. 
 RADARS 
 ETERS NEEDED TO DESCRIBE THE 3," PERFORMANCE  THE LAST FIGURE TO CONSIDER IS THE DETEC 
 ASPECT 3EARCH USES HIGH 
 Thus, we can infer that urban construction such as buildings and transport facilities may drive subsidence.   Figure 12. Maps show the satellite images of Region 2 on 21 January 2015 ( a) and 9 December 2017 ( b). 
 Its efficiency is  40 percent and gain is 30 dB. A peak beam voltage of 145 kV is required. The VA-812C formed  the basis for the design of the VA-842, a tube used in the Ballistic Missile Early Warning  System (BMEWS), with a demonstrated life in excess of 50,000 hours. 
 DEPENDENT    TRANSLATION ERRORS    ERRORS IN CONVERTING    ANTENNA POSITION TO    ANGULAR COORDINATES ,EVELING OF PEDESTAL .ORTH    ALIGNMENT3TATIC FLEXURE OF PEDESTAL    AND ANTENNA/RTHOGONALITY OF AXES SOLAR    HEATING$YNAMIC DEFLECTION OF PEDESTAL    AND ANTENNA"EARING WOBBLE$ATA GEAR NONLINEARITY    AND BACKLASH$ATA TAKEOFF NONLINEARITY    AND GRANULARITY 4ARGET 
 DENSITY PLOT 4HE SPECTRAL 
 CONVERSION DERIVES FROM ANALOG DOWNCONVERSION AND SAMPLING  AS ILLUSTRATED IN THE  FREQUENCY DOMAIN IN &IGURE  4HE SPECTRA ON THE FIRST AND    LINES REPRESENT SIGNALS  AT VARIOUS POINTS IN THE SYSTEM  AND THE SPECTRA ON THE    AND r LINES  RESPECTIVELY  REP 
 12-20, 1956.  19. Hannan, P. 
 Using technology similar to that of the antenna sidelobe canceler,  nulls are adaptively placed at those frequencies containing large clutter. A three-loop adaptive  canceler, for example, can adaptively place three nulls at three different frequencies or it can  place the three nulls so as to make a single wide notch, depending on the nature of the clutter  spectrum.  Compensation for clutter doppler spread. 
 If it is determined from an on-board threat table, current rules of engage - ment, or mission plan, high power density jamming based on the corresponding  on-board techniques table may be initiated using the high-gain nose aperture.84   FIGURE 5.24  MFAR ECM example9 ch05.indd   27 12/17/07   1:27:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 
 22.1  22.1 Introducti on  .............................................................  22.1  22.2 SBR Systems Considerations  ................................  22.1  Types of SBR  .................................................... 
 STAGE AMPLIFIER &ILTERING  CONSIS 
 However, with our method, we can achieve the scores of 0.9555 and 0.9573, which proves that our method performs well in all of the three classes. 3.8. Comparison with Other Methods The good performance has been shown from the results in Tables 2–8. 
 Smith: M~iltipatli Limitations on Low-Angle Radar Tracking, I EEE Tmtu..  vol. AES-14, pp. 
   OR  S L   \SIN \P    WHICH  IS ALWAYS TRUE IF  SK     7HEN SCANNING IS LIMITED  THE VALUE OF  SK MAY BE  INCREASED  FOR EXAMPLE  TO  SK    FOR SCANNING TO A MAXIMUM OF n OR  SK     FOR SCANNING TO A MAXIMUM OF on &OR LARGER VALUES OF SK  GRATING LOBES OCCUR AT ANGLES P  GIVEN BY  SIN SINQQL oN S    WHEN N IS AN INTEGER  )N THE LIMIT  THE INEQUALITY %Q   DOES ALLOW A GRATING 
 3ANDWICH )N CONTRAST TO THE ! 
 modeled as that from a number of independent, random  scatterers, with no one individual scatterer producing an ec:ho of magnitude commensurate  with the resultant echo from all scatterers, then the amplitude fluctuations of the sea echo is  described by the gaussian probability density function, [Eq. (2.15)]. The statistical fluctuations  of the envelope v of such an echo at the output of the envelope detector in the radar receiver  is given by the Rayleigh probability density function (pdf), which is  '  . 
 M  
 TROLS THESE ISSUES 4HE POWER 
 t 3.  ('  10.2 MATCHED-FILTER RECEIVER1 .s  A network whose frequency-response function maximizes the output peak-signal-to-mean­ noise (power) ratio is called a matched filter. This criterion, or its equivalent, is used for the  design of almost all radar receivers. 
     
 Finally, the simulations are performed on both point target and extended target to demonstrate the scintillation-induced imaging distortion. A group of 500-time Monte-Carlo simulations are carried out to validate the theoretical analysis. 2. 
 The half-power beamwidth (3, in radians, of the array factor of such an antenna is given by P = I (21.1) In this expression, L is the length of the physical array, and X is the wavelength. In the synthetic antenna* case, only a single radiating element is used in most instances. This antenna is translated to take up sequential positions along a line. 
 BANDWIDTH PRODUCT OF THE WAVEFORM  4YPICALLY  THE PULSE COMPRESSION RATIO AND TIME 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 24.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 Superresolution . The resolution of a conventional antenna is limited by the well- known Rayleigh criterion, which states that two equal-amplitude noise sources can be  resolved if they are separated in angle by 0.8 l/L, in radians, where l is the wavelength  and L is the aperture length. 
 SNR and time-sidelobe performance poor for larger doppler.Doppler coverage Good range sidelobes. N 1/2 for an TV-element code.Good range sidelobes possible with no weighting. Sidelobes determined by waveform design.Requires weighting to reduce the range sidelobes below (sin x)/x falloff.Range sidelobe level Bandwidth, pulse width, and code can be varied.Limited to one bandwidth and pulse width per compression network.Bandwidth and pulse width can be varied.Limited to one bandwidth and pulse width per compression network.Bandwidth and pulse width can be varied.Waveform flexibility Fair clutter rejection. 
 4.1 1. However,  clutter that enters the radar receiver via the antenna sidelobes has doppler frequencies that  canriot be rejected by conventional filtering, since targets of interest can have the same doppler  as the sidelobe clutter. An adaptive array antenna can place nulls in the direction of sidelobe  clutter by using the sidelobe clutter itself as the signal to be cancelled. 
 Williams, P. D. L.: Limitations of Radar Techniques for the Detection of Small Sirrfacc Targets in  Clutter, The Rudio and Electronic Engineer, vol. 
 Mapping interactions between geology, subsurface resource exploitation and urban development in transforming cities using insar persistent scatterers: Two decades of change in Florence, Italy. Appl. Geogr. 
 TORS ARE USED IN WHICH THE FIRST  THE  ! CORRELATOR  RESOLVES THE RANGE AMBIGUITIES  WITHIN SOME NOMINAL RANGE  SAY   NM  BEYOND WHICH SIDELOBE DISCRETES ARE NOT LIKELY TO BE DETECTED ! SECOND CORRELATOR  THE  " CORRELATOR  RESOLVES THE RANGE  AMBIGUITIES OUT TO THE SAME RANGE  BUT BEFORE A TARGET CAN ENTER THE  " CORRELATOR   ITS AMPLITUDE IS THRESHOLDED BY A RANGE 
 The vibration  sensitivity of an oscillator is specified by the factional frequency vibration sensitivity,  commonly know as the g-sensitivity . Typically, a single constant value is specified. In  practice, the sensitivity varies significantly with vibration frequency and is different  for each axis. 
 In acquisition the threshold circuits are normally scanned by some type of readout mechanism. This is fundamentally a computer-type operation. Doppler Trackers. 
  TRANSISTOR  DRIVING CONFIGURATION FOR THE TRANSMIT AMPLIFIER AND A QUADRATURE SPLITTER ON THE OUTPUT TO GENERATE A POLAR 
 Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar.  AN INTRODUCTION AND OVERVIEW OF RADAR  1.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 also an example of a radar. An excellent measure of the success of radar for military  air defense is the large amounts of money that have been spent on methods to counter  its effectiveness. 
 Vand Aare the velocity and acceleration of the aircraft. The velocity vector is in the YOZ plane. His the aircraft altitude. 
 Ryde, “The attenuation and radar echoes produced at centimetre wavelengths by various  meteorological phenomena,” in Meteorological Factors in Radio Wave Propagation , London:  Physical Society, 1946, pp. 169–188. ch19.indd   42 12/20/07   5:39:20 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 CURRENT OR SELF 
 17,  pp. 5 1-55, May, 1974.  82. 
 9, pt. 5, pp. 55-62, 1961. 
 G. Hansen13 © IEEE 1970 ) ch07.indd   7 12/17/07   2:13:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 11)7ti IEEE Alllc'III1C/S C1l1dI'l'OpCl{/C1licl/I SoddySymposium. Oct.II15.1976. pp.589582,IEEECal.no.76 CIf1121-3i\r. 
  D" AT 6"  THUS ILLUSTRATING THE ADVANTAGE OF PULSE 
 Radar System Engineering  Chapter 4 – Information Content of Radar Signals  19     4 Information Content in Radar Signals   In the section for the Radar Equation the realizable information content of Radar was implicitly  demonstrated.  Depending on the principle that is put to use, the following information can be o b- tained from a Radar signal and/or a series of signals:   Distance or Range  € R,  Velocity and/or Speed (change in distance over time) € dR dt,  Azimuth ψ, change of the Azimuth over time  € dψ dt  Elevation ϑ, change i n elevation over time  € dϑ dt  Size of the target  € s,  Shape of the target € dσ dψ,  Polarization of the target  € svv &  € shh,  Signature (information about the target) [ σ].  The most important and most often evaluated information would be:   Distance or Range,   Velocity and/or Speed,   Direction. 
 5μs pulse transmission. This was equivalent to about 3/4 of a mile although it was reported that some response could often be observed at shorter ranges. A CCDU trial of Lucero was undertaken in June 1943 to determine its opera- tional performance against a BABS beacon in a Wellington VIII [ 6]. 
 OPPORTUNITYDESIGNED FOR OTHER FUNCTIONS  INCLUDING RADAR AND COMMUNICATIONS  BUT FOUND SUITABLE FOR BISTATIC OPERATION 4HE COOPERATIVE TRANSMITTER IS CONTROLLED BY ALLIED OR FRIENDLY FORCES THE NONCOOPERATIVE TRANSMITTER  BY HOSTILE OR NEUTRAL FORCES 4ABLE  SUM 
 Inversions aloft, due to large-scale subsidence will  lead to superrefractive layers aloft. Superrefractive layers will lead to an increase of  radar detection ranges and extensions of the radio horizon. The effects of a superrefractive layer upon a surface-based system are directly  related to its height above the Earth’s surface. 
 SPACE (IGH POWER JAMMING (I0WR*AM  IS A COUNTERMEASURE AVAILABLE FROM !%3!S DUE TO THEIR NATURAL BROADBAND  BEAM AGILE  HIGH GAIN  AND HIGH POWER ATTRIBUTES !%3!S ALSO ALLOW LONG RANGE AIR 
 OFFv AND VARIABILITY AROUND THIS OPERATING POINT CAN CAUSE LARGE CIRCUIT PERFORMANCE VARIABILITY IF DESIGNED POORLY "OTH GAIN AND NOISE FIGURES ARE HIGHLY DEPEN 
 GENERATED SOLUTIONS  ! POTENTIALLY SIGNIFICANT MECHANISM  IN OCEAN SURFACE WAVE GENERATION AND WAVE SCATTERING v  )%%% * /CEANIC %NG   VOL /% 
 Because the energy passes through the phase shifters twice, they need only  half the phase-shift capability of a lens array or a conventional array; i.e., 180" of one-way  j>ll:~se shift is adequate, rather than 360". The pliase shifters, however, must be reciprocal. As  ~vith tl,e lens array, multiple bearns can be generated with additional feed horns. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.66  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 azimuth sidelobes. The array is a slotted waveguide design of 36 sticks and 94 horizon - tally polarized slots per stick. 
 Nov.8-10.1977,Arlington, Va.,pp.40-45,IEEEPublication 77CH1250-0AES. 136.Sangiolo. 1.B.,andA.B.Rohwer: Structural DesignImprovements ofESSeO Radomes and Antennas, IEEE1977Mechanical Engineering inRadarSymposium, Nov.8-10,1977, Arlington. 
 BEAM CLUTTER LEVEL IS AT THE SATURATION POINT OF THE RECEIVER $YNAMIC 2ANGE  $YNAMIC RANGE  AS DISCUSSED HERE  CAN BE REFERRED TO AS  INSTAN 
 The  noise figure of an image-recovery circuit (Fig. 9.4) is competitive with other receiver front­ ends. The irhage-recovery mixer is attractive as a receiver front-end because of its high dy­ namic range, low intermodulation products, less susceptibility to burnout, and less cost as  compared to other front-ends. 
 R-scope. AnA-scope withasegment ofthetimebaseexpanded neartheblipforgreateraccuracy in distancr measurement. RHI,orRange-Height Indicator. 
 The single-scan probability-of-detection curves shown in Fig. 17.22 have been used to compute the 85 percent cumulative probability of detection for the variable-scan case, shown in Fig. 17.23. 
 7 Thus the delay line cancellers with response sin" 1t/& Tare" optimum" in the sense  that they approximate the filters which maximize the average signal-to-clutter ratio or  the average clutter attentuation. It also approximates the filter which maximizes the probabil­ ity of detection for a target at the midband doppler frequency or its harmonics.6  In spite of the fact that such filters are" optimum" in several senses as mentioned above,  they do not necessarily have characteristics that are always desirable for an MTI filter. The  notches at de, at the prf, and the harmonics of the prf are increasingly broad with increasing  number of delay lines. 
 ARRAY ANTENNA v  )%%% 4RANS  VOL !0 
 toobtainatotalpowergreaterthancanbeobtained fromasingletransmitter. Controloftlteradiation pattern. Aparticular radiation patternmaybemorereadilyobtained withthearraythanwithothermicrowave antennas sincetheamplitude andphaseofeach arrayelement maybeindividually controlled. 
  
 K-scope. A modified A-scope in which a target appears as a pair of vertical deflections. When the radar  antenna is correctly pointed at the target, the two deflections are of equal height, and when not so  pointed, the dikrence in deflection amplitude is an indication of the direction and magnitude of the  pointing error. 
 The functional relationships between the rheological parameters and deformation along the Synthetic Aperture Radar ( SAR) line of sight are constructed, and a method for rheological parameter estimation is provided. To assess the feasibility and accuracy of the presented model, both simulated and real deformation data over a stretch of the Lungui highway (built on soft clay subgrade in Guangdong province, China) are investigated with TerraSAR-X satellite imagery. With the proposed deformation model, the unknown rheological parameters over all the high coherence points are obtained and the deformation time-series are generated. 
 pp. 77 XO. F--ehruary. 
 BASED  3!2   FOLLOWING EXTENSIVE PROGRAMS IN OPTICAL REMOTE SENSING SATELLITES AND AIRBORNE  IMAGING RADAR DEVELOPMENT 2)3!4S DEPLOYABLE ANTENNA  M BY  M  IS AN ACTIVE PHASED ARRAY COMPRISED OF  # 
 Backscatter  from rough ice, such as floes and pack ice, can produce an effect on the radar display similar  to sea clutter. However, the backscatter from rough ice can be distinguished from sea cluttcr  since its ~affern on the display will remain stationary from scan to scan but the sea clutter  pattern will change with time.33 Measurements made over ice fields in the region of Thule,  Gree~~land,~' indicated the radar backscatter (a0) to vary linearly with frequency over a range  of grazing arlgles from 1 to 10". It was also found that o0 was proportional to the elevation  angle over grazing angles from 2" to lo0, but was inversely proportional to grazing angle over  the regiori from 1" to 2". 
   AMPLIFIER CONFIGURA 
 VIC did not include the lock –follow capability of ASV Mk. VIA and B. The radars in the CCDU and ASWDU trials referenced here did not have AFC, but appeared to have Attenuator Type 58, with an adjustable attenuation rate control. 
 ON AT THE LEFT AND RIGHT SIDES  n  4HE LARGE SPECULAR RETURN FROM THE  PLATE AT THE CENTER OF THE CHART IS PREDICTED WITH QUITE GOOD ACCURACY BY THE FLAT 
 13,Chap. 2). In this region, however, the field strength normally diminishes sorapidly with increasing range that any additional radar coverage thus obtained isoflittle value. 
 An example is the ogive, a spindle-shaped object formed by rotating an arc of a circle about its chord. Figure 11.8 is the RCS pattern of a 39-wavelength 15° half-angle ogive recorded for hor- izontal polarization (incident electric field in the plane of the ogive axis and the line of sight). The large lobe at the right side of the pattern is a specular echo in the broadside sector, and the sequence of peaks at the left side is the contribution of the surface traveling wave near end-on incidence. 
 At the septum the double- humped E field is represented by the combined TE10 and TE30 modes subtracting at the center and adding at the TE30-mode outer peaks. However, since the two modes propagate at different velocities, a point is reached farther down the double-width guide where the two modes add in the center and subtract at the outer humps of the TE30 mode. The result is a sum-signal E field concentrated toward the center of the feed aperture. 
 Arlington. Va .• Apr. 21 23. 
 LAUNCHED BALLISTIC MISSILES 4HE TWO 
 Collector current is drawn only when the input voltage  exceeds the reverse bias across the input and the output voltage is developed across a  resonant-tuned load. The net result is high amplifier efficiency. The practical implica - tions of a Class-C-biased amplifier stage are as follows: ● No quiescent dc current is drawn while the device is not being driven, such as in  the radar receive mode. 
 E. Wahl, P. H. 
 Edmonson, C. K. Campbell, and S. 
 But even more  importantly, from the operational perspective, HF radars must maintain a real-time  ionospheric model (RTIM) that is intimately linked with the radar subsystems, serving  to guide frequency selection, radiated power, task scheduling, coordinate registration  (converting from the radar coordinates of time delay and angle-of-arrival to geographi - cal coordinates), ionospheric mode structure interpretation, and association of mul - tiple tracks from a single target. Unlike the climatological models, RTIMs must be  updated continuously with information from an auxiliary network of beacons. Oblique  and vertical incidence sounders and transponders have been deployed for this purpose. 
   &)'52%   *AMMER CANCELLATION AT SUB 
 SIGNAL EXCITATION WITH THE TWO ANTENNAS PROVIDES A TWO 
 %ARTH ORBITS ,%/  4YPICAL ,%/ ALTITUDES SPAN  KM TO  KM ,OWER ALTITUDES INCUR LARGER ATMOSPHERIC DRAG  WHEREAS HIGHER ALTITUDES IMPLY HIGHER RADIA 
 4. Schafer, C. R.: Phase-selective Detectors, Electronics, vol. 
 NMI RANGE OF A  ALL CLUTTER AT A MOUNTAINOUS SITE AND B  CLUTTER THAT EXCEEDS THE SYSTEM NOISE LEVEL BY  D" . 
 2.8b, where integration loss in decibels  is defined as L;(n) = 10 log [l/E;(n)]. The integration-improvement factor (or the integration  loss) is not a sensitive function of either the probability of detection or the probability of false  alarm.  The parameter n1 for the curves of Fig. 
 SIDERED 3INCE MAIN 
 (1.2)] of tlie radar,  target B is at a distance greater than Runom,, but less than 2RUnamb, while target C is greater  tliati 2R,,,,,,,, but less than 3RUn,,,,,. The appearance of the three targets on an A-scope is  sketched in Fig. 2.266. 
 9 (degrees) FIG. 16.17 Sum and difference patterns used to determine DPCA performance. and the subscript./ denotes the component of the pair. 
 Sheppard: AN/SPY-I Phased-Array Antenna, Microwal'e J., vol. 17,  pp. 51-55, May, 1974. 
 ................................ .. 10  Resolution Cell  ................................ 
 Carefulobservation ofperformance-monitoring instru­ mentsandtimelypreventative maintenance candomuchtokeepradarperformance upto designlevel.Radarcharacteristics thatmightbemonitored includetransmitter power,receiver noisefigure,thespectrum and/orshapeofthetransmitted pulse,andthedecaytimeoftheTR tube. I\.goodestimate ofthefielddegradation isdifficulttoobtainsinceitcannotbepredicted andisdependent upontheparticular radardesignand"theconditions underwhichitis operating. Adegradation of3dBissometimes assumed whennootherinformation is available. 
 Micrmvar·e J., vol. 2.  pp 31 38, Deccm her, 1959; pt. 
 D" WIDTH  "  AS FOLLOWS  3F "F "' LN  EXPLN     
 6.6CROSSED-FIELD AMPLIFIERS Thecrossed-field amplifier (CFA),likethemagnetron oscillator, ischaracterized bymagnetic andelectricfieldsthatareperpendicular toeachother.Suchtubesareofhighefficiency (40to 60percent), relatively lowvoltage(compared withalinear-beam tube),andoflightweightand smallsizesoastomakethemofinterestformobileapplications. CFAsarecapableofbroad bandwidth (10to20percent) withhighpeakpower,butthegainisusuallymodest.Theyhave goodphasestability, andanumberofCFAscanbeoperated inparallelforgreaterpower. CFAscanbeusedasapowerboosterfollowing amagnetron oscillator, asthehigh-power stageinmaster-oscillator power-amplifier (MOPA) transmitters withotherCFAsoraTWT asthedriverstage,orastheindividual transmitters ofahigh-power phased-array radar.. 
 The radar scans in azimuth and detects a couplet in radial velocity at constant range. The azimuthal shear is given simply by the expression dvr 2vr — « — (23.49)ax roc where x is in the direction orthogonal to the radius r and d is the angle subtended by the circulation at range r. Because mesocyclones, which spawn tornadoes, can be many kilometers in diameter, radars with 1° beams have the spatial resolution to detect mesocyclones at ranges in excess of 60 km. 
    S PA     .   '2/5.$ 0%.%42!4).' 2!$!2   Ó£° WHERE  0T   TRANSMITTED POWER IN WATTS  0R   RECEIVED POWER IN WATTS  !   ANTENNA GAIN  '   ANTENNA EFFECTIVE APERTURE  2   RANGE IN METERS  @   TARGET RADAR CROSS SECTION  K   CALIBRATION COEFFICIENT 4HE CUMULATIVE LOSSES INCLUDE THE TRANSMISSION COEFFICIENTS INTO THE GROUND THE  SPREADING LOSSES DESCRIBE THE 2n LOSSES FOR A TARGET OF  M AND THE ATTENUATION  LOSSES ARE FOR A SOIL WITH A  DR OF  AND TAN  C  OF  &IXED LOSSES INCLUDE THE TRANS 
 ANE-4, pp. 103-1 12,  September. 1957. 
 2. N. J. 
 Note that curves D to H are additive-noise measurements.dB BELOW CARRIER 1 Hz BANDWIDTH . higher offset frequencies, one runs into the Nyquist restriction. For any fixed de- lay length, there is a corresponding offset frequency where the servo gain must go to zero or the whole system will become unstable. 
 However, longtime and wide range monitoring of land subsidence is lacking. The causes of subsidence also require further study, such as natural conditions and human activities. We use small baseline subset (SBAS) interferometric synthetic aperture radar (InSAR) method and high-resolution RADARSAT-2 images acquired between 2015 and 2018 to derive subsidence. 
 Another common cause of ducting is the movement of warm dry air, from land, over  cooler bodies of water. Warm dry air blown out over the cooler sea is cooled at the lowest  layers and produces a temperature inversion. At the same time, moisture is added from the sea  to produce a moisture gradient. 
 The most accurate and convenient method for the measurement of the lower frequency noise is the fast Fourier transform (FFT). The method is too time-consuming for analysis of the far-out phase noise. With computer control of all of the components of the test equipment almost any desired measurement can be made, adjusted for filter shape, and printed out. 
 BASED  DUCT ARE THE SAME AS THOSE FOR AN ELEVATED DUCT )N FACT  A SURFACE 
 W. N. and M. 
 SPHERE v 'EOFTS  0URA !PPL  VOL   PP n    * 7 2YDE  h4HE ATTENUATION AND RADAR ECHOES PRODUCED AT CENTIMETRE WAVELENGTHS BY VARIOUS  METEOROLOGICAL PHENOMENA v IN  -ETEOROLOGICAL &ACTORS IN 2ADIO 7AVE 0ROPAGATION   ,ONDON  0HYSICAL 3OCIETY    PP n.   -%4%/2/,/')#!, 2!$!2   £°{Î  * / ,AWS AND $ ! 0ARSONS  h4HE RELATIONSHIP OF RAINDROP SIZE TO INTENSITY v IN  TH !NN -EET  4RANS !M 'EOPHYS 5NION    PP n  2 ' -EDHURST  h2AINFALL ATTENUATION OF CENTIMETER WAVES COMPARISON OF THEORY AND MEASURE 
 Phys., vol. 24,  pp. 128-131, February, 1953. 
 Whentheprfmustbesohighthatthenumber ofrangeambiguities istoolargetobe easilyresolved, theperformance ofthepulse-doppler radarapproaches thatoftheCWdoppler radar.Thepulse-doppler radar,liketheCWradar,maybelimitedinitsabilitytomeasure rangeundertheseconditions. Evenso,thepulse-doppler radarhasanadvanta&e overtheCW radarinthatthedetection performance isnotlimitedbytransmitter leakageorhysignals reflected fromnearbyclutterorfromtheradome. Thepulse-doppler radaravoidsthis difficulty sinceitsreceiver isturnedoffduringtransmission, whereas theCWradarreceivcr is alwayson.Ontheotherhand,thedetection capability ofthepulse-doppler radarisreducl:J becauseoftheblindspotsinrangeresulting fromthehighprf. 
 &AMIL  AND % 0OTTIER  h-ULTI 
 (Merrill Ivan), date. TK6575.R262 1990 621.3848—dc20 89-35217 McGraw-Hill A Division of The McGraw-Hill Companies Copyright © 1990 by McGraw-Hill, Inc. All rights reserved. 
 DIMENSIONAL PHASE MONOPULSE HAS FOUR PHASE CENTERS  $0#! HAS  TWO OR MORE PHASE CENTERS  A RADAR WITH A GUARD HORN FOR SIDELOBE SUPPRESSION HAS TWO  PHASE CENTERS  AND AN ADAPTIVE ARRAY MAY HAVE MANY PHASE CENTERS n 34!0 IS AN  EXTENSION OF THE CLASSIC THEORY FOR A MATCHED FILTER IN THE PRESENCE OF NONnWHITE NOISE  WHICH INCLUDES BOTH TIME AND SPACE /VERALL WEAPON SYSTEM REQUIREMENTS USUALLY FAVOR  8 OR + U BAND FOR THE OPERATING  FREQUENCY OF A -&!2 )N ADDITION  THE -&!2 APERTURES AND ASSOCIATED TRANSMITTER ARE USUALLY THE LARGEST ON AN AIRCRAFT AND HENCE  CAN CREATE THE HIGHEST %FFECTIVE 2ADIATED 0OWER %20  FOR JAMMING ADVERSARY RADARS AND DATA LINKS  WHERE THESE ARE IN 
 From it,thelentih ofmercurv column can becalculated accord- ingtotheformula D=L(17.42 +0.00522’), (18) with anestimated probable error of0.06 percent between 10”C and 40”C, where Disthedelay inmicroseconds, Lthelength ininches, Tthecenti- grade temperature. The two quantities tobechosen, along with theline configuration and the end-cell type, arethe carrier frequency and tube diameter. These enter into thedesign mainly inconnection with attenuation, bandwidth, and demodulation,. 
 2Certain modulators, such astherotary gap, cannot betriggered atIll. Other types canbetriggered buthave sovariable aresponse time that themodulator pulse itself must beused forsynchronization inorder toprovide thenecessarv precision.. SEC. 
 Thus a medium resolution radar might have a  20 dB advantage over low-resolution radars in the detection of targets in land clutter. The  I----+----t-----··-- -_.'--.-.----.494INTRODUCTION TORADAR SYSTEMS 10....------,----r--,.----,---,----,--.......,---r--, III~0f---+---+--+-- Q b g-10- I__~ (; ~ '§-20/' Qj /~I ~-30V1 : Il3-40 ---+----+---+----+--t----~t---f------· --.--.- U I -50L-_.L-_-L-_--'-_----.l..I __L....---_-'---_-=-'":-_---:-:_---:'o102030405060708090 Grazingangle.J Figure13.10Cross-section perunitareaofcultivated terrainillustrating theincrease ofaOwithdecreasing grazing angleforsmallvaluesofgrazing angle.Xband,horil.Ontal polariLation. (fromKul:UIIJ Spetller,3B COllrtesy J.Res.Nat.Bllr.Stds.) mountainous terrainalsoshowsnofrequency dependence fromLtoXhandhutiscon­ siderably loweratUHF;roughhills,desert,andcultivated farmland showalineardepen­ dencewithfrequency; andthebackscatter frommarshvariesasthe~poweroffrequency. 
 The selection of the lower cutoff might  be at the option of the operator or it can be done adaptively. A variable lower cutoff might be  advantageous when the width of the clutter spectrum changes with time as when the radar  receives unwanted echoes from birds. A relatively wide notch at zero frequency is needed to  remove moving birds. 
 FEED SYSTEMS 4HEY  FREQUENTLY COMBINE A NUMBER OF RADIATORS INTO SUBARRAYS  AND THE SUBARRAYS ARE THEN COMBINED IN SERIES OR IN PARALLEL TO FORM SUM AND DIFFERENCE PATTERNS &IGURE A SHOWS A  MATCHED CORPORATE FEED   WHICH IS ASSEMBLED FROM MATCHED  HYBRIDS 4HE OUT 
 CW AND FREQUENCY-MODULATED RADAR 73  The separate antennas of the AN/MPQ-46 CW tracker-illurninator of.tlle Hawk rnissile  system are shown in Fig. 3.3. The Cassegrain receiving antenna is on the right. 
 PULSE BINOMIAL 
 This formula is applicable to a single-response receiver (one for which a single RF input frequency corresponds to only one output or IF frequency and vice versa). Methods of computing noise temperatures when a double- or multiple- response receiver is used (e.g., for a superheterodyne receiver without preselection) are described in Refs. 17 and 25. 
 B., Jr.: Signal-to-noise Ratios in Band-pass Limiters, J. Appl. Phys., vol. 
 FIELD  AND THEREFORE APPEAR SMALLER THAN THEIR PHYSICAL CROSS SECTION.   2%&,%#4/2 !.4%..!3   £Ó°£x                  
 Ê*," 
 The primary output of a tracking radar is the target location determined from the pointing angles of the beam and position of its range-tracking gates. The angle location is the data obtained from synchros or encoders on the antenna tracking axes shafts (or data from a beam-positioning computer of an electronic-scan phased array radar). In some cases, tracking lag is measured by converting tracking-lag-error voltages from the tracking loops to units of angle. 
 TRUM AND  INVERSELY  TO USE RADAR BACKSCATTER MEASUREMENTS TO PROVIDE REMOTE SENSING OF THE SEA SURFACE FOR OCEANOGRAPHIC AND METEOROLOGICAL APPLICATIONSPROVIDED  OF COURSE  THAT IT CORRECTLY DESCRIBES THIS RELATIONSHIP !LTHOUGH %Q  SUCCESSFULLY PREDICTS TO ST 
 It is sometimes called the phase  Itistor.j. or sigrttrl I~istnry. The image that results by illuminating the film is focused on a tilted  plane siricc the curvature of tlie wavcfrorit is proportional to the range. 
 Sincetheelements onthesideofthecylindrical array opposite fromthedirection ofpropagation donotcontribute energyinthedesireddirection, theyarenotexcited. Unliketheplanararray,thecircular symmetry ensures thatmutual coupling between elements isalwaysthesameasthebeamscansinazimuth. Thetruncated conehassimilarproperties tothecylindrical array,andmightbeutilized insteadofthecylinder whenthebeamistobescanned inelevation aswellasazimuth. 
 The same tapped delay line can be used  as the receiver matched filter if the input is applied at the right-hand terminal.  The known Barker codes are shown in Table 11.2. The longest is of length 13. 
 ING ANGLES AND HORIZONTAL POLARIZATIONS WITH WHICH MOST SHIPBOARD RADARS OPERATE &IGURE  COMPARES THE CORRELATION FUNCTION OF SEA CLUTTER 8 BAND  LOW GRAZING ANGLE  ( POLARIZATION  WITH AND WITHOUT RAIN FOR A  
 H. Doherty, D. T. 
 £È°{{  2!$!2 (!.$"//+  -EASUREMENTS WITH SUITABLE AVERAGING IN FREQUENCY OR ILLUMINATION ANGLE DEMONSTRATE  THAT SNOW 
 ÓÓ°Ó  2!$!2 (!.$"//+  )N THE MARINE WORLD  THESE HAVE BEEN CALLED  .EW 4ECHNOLOGY 2ADARS  4HEY ARE PER 
 8.7.) The transmitted waveform is similar to the  frequency-modulated pulse compression waveform (chirp) discussed in Sec. 11.5. The carrier  frequencies of any echo pulses returned to the radar will be determined by the elevation angle  of the targets. 
 These frequency bands are attractive when a radar of smaller  size has to be used for an application not requiring long range. The Airport Surface  Detection Equipment (ASDE) generally found on top of the control tower at major  airports has been at Ku band, primarily because of its better resolution than X band. In  the original K band, there is a water-vapor absorption line at 22.2 GHz, which causes  attenuation that can be a serious problem in some applications. 
 The receiver may be considered linear irp to the output of the IF. It is shown  by Van Vieck and Middleton3 that maximizing the signal-to-noise ratio at the output of the IF  is equivalent to maximizing the video output. The advantage of considering the signal-to-noise  ratio at the IF is that the assumption of linearity may be made. 
 The timing for bomb release was Figure 4.10. Scanning unit type 68, (a) [ 8] and (b) [ 10]. Figure 4.9. 
 70–78, January 1985.  86. C.-C. 
 An  486INTRODUCTION TORADAR SYSTEMS (4)thedetection decision wasdetermined bywhether ornotthereceiver outputcrossed a threshold thatdepended onthedesiredprobability offalsealarm.Whenthenoise,orc1utter,is notdescribed byaRayleigh pdf,thereceiver modelofChap.2isnotoptimum andcancause degraded performance. Thehigher"tails"oftheprobability densityfunction ofnon-Rayleigh cluttermeanthattherewillbeagreaternumberoffalsealarmsintheconventional receiver designed onthebasisofRayleigh statistics. Thefalsealarmswithnon-Rayleigh cluttercanbe reduced toanydesiredlevelbyraisingthereceiver threshold. 
 86-89, Apr. D, 1960.  56. 
 INTRODUCTION  The GEOSA T radar altimeter is similar to the Seas at  altimeter in its mechanical, thermal, and electrical in­ terfaces. Changes include the use of a 20-watt long-life  traveling wave tube amplifier, an 8085 microprocessor  for improved radiation tolerance, a digitally synthesized  transmit waveform generator (i.e., a linear FM or  "chirp" pulse), and a gallium arsenide field-effect­ transistor preamplifier for the receiver front end.  RETURN SIGNAL CHARACTERISTICS  The characteristics of a signal reflected from the ocean  surface strongly influence an altimeter's design and im­ pose limits on the precision attainable, even for a per­ fect instrument. 
 1047 —Low-power airborne pulser. between pulses must beused. For example, a60-cycle full-wave rectifier isbrought tofull voltage only 120times persecond, sothat apulse rate of1200 cpswould draw 10pulses ofpower between successive recharge cycles. 
 He is also involved in the exploitation of a new generation of wide-band SAR data. He has co-authored more than 150 journal papers, book chapters, and conference communications and serves as a reviewer for several international peer-reviewed journals. He currently chairs sessions in international symposia on remote sensing and signal processing (IEEE, SPIE). 
 18.50 Other Internal Sources of Error  ..........................  18.52  18.11 Summary of Sources of Error  .................................  18.53  Angle Measurement Errors  ................................ 
 INTERVAL RATIO &)'52%   6ELOCITY RESPONSE CURVE THREE 
 8.8.  Antennas for ground-based radars are often subjected to high winds, icing, andlor temperature . ,2  extremes. 
 The transmitting  power of the Radar will partially be absorbed by the atmosphere and will be re -radiated as  noise.  With absorption noise as a function of the surrounding temperature of the atmosphere T u = 260°K and with the atmospheric attenuation L a, the effective noise temperature T a is as  follows:   € Ta=Tu(La−1);where Tu=260°K (6.7)  . Radar System Engineering  Chapter 6 – Radar Receiver Noise and Target Detection  33     La/dB 1,3 3 10  Ta/°K 67 260 2340   Radar Frequency (MHz)Attenuation for two-way Transition of entire Atmosphere (dB)   Figure 6.5  Two-way atmospheric attenuation. 
 FIGURE 22.1  Ship’s integrated bridge system ( Courtesy of SAM-Electronics GmbH )  ch22.indd   2 12/17/07   3:02:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 
 21.Temes,C.L.:Relativistic Considerations ofDoppler Shift,IRETrailS.,vol.ANE-6, p.37,March. 1959. 22.Knop,C.M.:ANoteonDoppler-Shifted Signals,Proc.IEEE,vol.54,pp.807-808, May,1966 23.Gill,T.P.:"TheDoppler Effect,"Academic Press,NewYork,1965. 
 24. Sensors 2019 ,19, 1701 16. Wu, Y.; Song, H.; Shang, X.; Zheng, J. 
  
 I'IWI'AGATION OFRADAR WAVES467 ).Sherwood. E.M.•andE.L.Ginzlon: Reflection Coeflkients ofIrregular Terrainat10Cm,Proc.IRE. vol.43.pp.R771'7X.July.1955 4.lIey.J.S..andS.J.Parsons: TheRadarMeasurement orLowAnglesofElevation, 1'1'0('.I'hys.Soc, ser.n,vol,69,pp..121.'2X,I(}56. 
   6OL  .ORWOOD  -! !RTECH (OUSE  )NC    PP n  * ! 3CHEER AND * , +URTZ   #OHERENT 2ADAR 0ERFORMANCE %STIMATION   .ORWOOD  -! !RTECH  (OUSE  )NC    PP n  3 * 'OLDMAN   0HASE .OISE !NALYSIS IN 2ADAR 3YSTEMS 5SING 0ERSONAL #OMPUTERS   #HAPTER    .EW 9ORK *OHN 7ILEY  3ONS  )NC    ' 6 4RUNK AND - 7 +IM  h!MBIGUITY RESOLUTION OF MULTIPLE TARGETS USING PULSE 
 204-221, September,  1956.  11. Rihaczek, A. 
 Klare, J.; Saalmann, O. MIRA-CLE X: A new imaging MIMO-radar for multi-purpose applications. In Proceedings of the 7th European Radar Conference (EuRAD), Paris, France, 30 September–1 October 2010; pp. 
 80. Trunk, G. V., B. 
 A forward-left and an aft-right are also fed by  the transmitter as a second channel. The two channels may be operated simultaneously or  timed-shared. By heterodyning in a mixing element the echo signal received in the fore and aft  beams, the doppler frequency is extracted. 
 TRONS 4HIS POTENTIALLY MAKES THEM EXTREMELY STABLE AND RELIABLE  WITH A RESULTANT LOW COST OF OWNERSHIP  THEREFORE  MEETING THE INCREASING DEMANDS OF SHIP OPERATORS . 
 Figure 8.4 shows the result when  the pulsewidth is increased to 100 µs to yield a waveform with an LFM slope equal  FIGURE   8. 2 LFM bandpass signal example (shown for T = 10 µs, B = 1 MHz,   f0 = 2 MHz) Mainlobe Width Time Delay Resolution (s) Range Resolution (m)  3.01 dB t3 = 0.886/ B ∆R3 = 0.886 c/B   3.9 dB t3.9 = 1/B ∆R3.9 = c/2B  6.02 dB t6 = 1.206/ B ∆R6 = 1.206 c/2B  10.0 dB t10 = 1.476/ B ∆R10 = 1.476 c/2BTABLE   8.1  LFM Waveform Time Delay and Range Resolution Widths ‡  These values of doppler shift are large for microwave radars and were selected to show the effect of range-doppler  coupling. ch08.indd   5 12/20/07   12:49:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 J. Atmos. Ocean. 
 PORTABLE  TRANSMIT AND RECEIVE ANTENNAS   WHICH ARE PLACED ON THE SURFACE OF THE GROUND AND MOVED IN A KNOWN PATTERN OVER THE SURFACE OF THE GROUND OR MATERIAL UNDER INVESTIGATION  AND AN IMAGE CAN BE GENERATED  IN REAL TIME  ON A DISPLAY EITHER IN GREY SCALE OR IN COLOR "Y SYSTEMATICALLY SURVEYING THE AREA IN A REGULAR GRID PATTERN  A RADAR IMAGE OF THE GROUND CAN BE BUILT UP '02 IMAGES ARE DISPLAYED EITHER AS TWO 
 The synthetic aperture LSA = VT is assumed small compared with  the range R to the center of the target region. As viewed from the target region (also  assumed small compared to R), the synthetic aperture subtends the synthetic aperture  angle ≈ LSA/R = VT/R. As the radar moves through its synthetic aperture, it views the  scene from slightly different angles. 
 Limiters cause the spectrum of strong clutter to spread into the canceler pass­ band, and result in the generation of additional residue that can significantly degrade MTI  performance as compared with a perfect linear system.  An example of the effect of limiting is shown in Fig. 4.32, which plots the improvement  factor for two-pulse and three-pulse cancelers with various levels of limiting.53 The abscissa  applies to a gaussian clutter spectrum that is generated either by clutter motion with standard  deviation <r,. 
 A display in which a target appears as a complete circle when the radar antenna is pointed at it  and in which the radius of the circle is proportional to target distance; incorrect aiming of the  antenna changes the circle to a segment whose arc length is inversely proportional to the magnitude  of the pointing error, and the position of the segment indicates the reciprocal of the pointing  direction of the antenna.  J-scope. A modified A-scope in which the time base is a circle and targets appear as radial deflections from  the time base. 
 The PRF and possibly the RF are changed from one CPI to the next. With this constraint only finite-impulse-response (FIR) filter designs are realistic candidates for the filter bank design. (Feedback filters require a number of pulses to settle after ei- ther the PRF or the RF is changed and thus would not be practical.) The number of pulses available during the time when a surveillance radar beam illuminates a potential target position is determined by system parameters and requirements such as beamwidth, PRF, volume to be scanned, and the re- quired data update rate. 
 TIME FILTERING RESPONSE WITH A MAIN BEAM ALONG THE  EXPECTED DOPPLER FREQUENCY AND ANGLE OF ARRIVAL OF TARGET AND DEEP NULLS ALONG THE JAMMER WALL AND THE CLUTTER RIDGE 4O PERFORM 34!0  THE RADAR SHOULD HAVE AN ARRAY OF . ANTENNAS  EACH WITH THEIR OWN RECEIVING CHANNEL AND !$# %ACH CHANNEL  RECEIVES - ECHOES FROM A TRANSMITTED TRAIN OF  - COHERENT PULSES !DAPTIVITY INVOLVES  THE .- ECHOES 4HE DETECTION PROBABILITY  0 $ FOR THE OPTIMUM FILTER OF %Q  IS FOR A CONSTANT  CROSS SECTION TARGET MODEL   01 0$  
 MAL NOISE  AS WELL AS TARGET SCINTILLATION  ARE MINIMIZED BY MAINTAINING THE TARGET AS CLOSELY AS POSSIBLE TO THE TRACKING AXES 4HE TECHNIQUE CALLED  ON 
 MANENT OR PERSISTENT  SCATTERERS  SUPPORT DIFFERENTIAL INTERFEROMETRIC MEASUREMENTS  THAT MAY SPAN MANY REPEAT VISITS OF THE RADAR  LEADING TO REMARKABLE SENSITIVITY TO SLOW 
 [14] Performance of A.S.V. Mk. III in Wellington and Halifax aircraft, C.C.D.U. 
 97, pp. 7249–7445, 1992. 162. 
 The presence of RF energy causes electrons to make multiple impacts to generate by  secondary emission a large electron cloud. The electron cloud moves in phase with the oscilla-  tion of the applied RF electric field to absorb energy from the RF field. The RF power is  dissipated thermally at the secondary emission surfaces. 
 IEEE Instrum. Meas. Mag. 
 $ISPLAY 6!$  "ROWNING AND 7EXLER  LATER SHOWED HOW THE 6!$ TECHNIQUE COULD BE EXTENDED TO MEASURE OTHER  PARAMETERS OF THE WIND FIELD INCLUDING WIND 
 RANGE SEEKERS AGAINST FIXED OR  SLOW MOVING TARGETS 4HE TARGET IS DETECTED AND DESIGNATED IN SOME OTHER MODE SUCH AS '-4)  $"3  3!2  OR 333 4HE DESIGNATED TARGET IS TRACKED IN RANGE AND ANGLE TO PROVIDE A MORE ACCURATE DISTANCE AND ANGLE TO THE TARGET 4HE TRACKING  MAY BE OPEN OR CLOSED LOOP 4HE ESTIMATES ARE THEN PROVIDED TO THE WEAPON BEFORE  AND AFTER LAUNCH $EPENDING ON DISTANCE  ANOTHER DESIGNATOR  SUCH AS A LASER  AND THE RADAR MAY BE ALTERNATELY SLAVED TO ONE ANOTHER "OTH THE RADAR AND THE OTHER DESIGNATOR MAY BE SUBJECT TO ATMOSPHERIC REFRACTION  ESPECIALLY AT LOW ALTITUDES  WHICH IS SOMETIMES ESTIMATED AND COMPENSATED 0RECISION 6ELOCITY 5PDATE  0RECISION VELOCITY UPDATE 065  IS USED FOR NAVIGA 
 19, 1957.  8. Lewis, B. 
  
 As soon as the cathode of Vb has travelled sufficiently  negative to approach the potential present on the control  grid of this valve, then V will start to pass current, and  . RADAR TIME-BASES 79  at once a voltage drop will be present across Rb. This  swings the suppressor grid of Ve negative, causing the  anode of Vc (and therefore the control grid of valve V6)  to go positive. 
 The range (or frequency) and azimuth angle are also discrete in actual situations. Assuming that the range sampling point is N, the azimuth sampling point is M. The frequency of nth(frequency) pulse in the burst is deﬁned by fn=f0+( n−1)Δf,n=1, 2,···,N, where f0is the initial frequency, Δfis the step interval, and the azimuth is discretized as θm=( m−1)Δθ,m=1, 2,···,M,(Δθis the angular interval). 
 SEGMENT SCHEME IS USED WITH THE FOLLOWING SEGMENTS NO 
 3/* AND ! 
 G. I. Belchansky and D. 
 The experimentally found blip-scan ratio curves are subject to many  limitations. but it represents one of the few methods for evaluating the performance of an  actual radar equipment against real targets under somewhat controlled conditions. 64 INTRODUCTION TO RADAR SYSTEMS  Cumulative probability of detection. 
 In semiactive systems this has generally been provided by the rear (reference) receiver (although an alternative on-board reference approach is also possible). In active systems the reference is derived directly from the transmitter-exciter. The reference must be spectrally pure (low-noise), and its frequency must ac- curately represent the illumination frequency to allow the target echo to fall within the bandwidth of the receiver. 
 While  prior radars took seconds to steer to a new location, phased arrays take microseconds.  In addition, the new location can be anywhere in a hemisphere. This chapter will be  devoted to arrays of this type. 
 It has a peak power of 0.5 to 2.0 MW and an  average power of0.5 to 3.5 kW. The gain is nominally 50 dB and its efficiency is greater than 45  percent. Its 1-dB bandwidth is 39 MHz, but it is inherently capable of greater values. 
 BANDWIDTH PRODUCT OF THE ,&- WAVEFORM IS EQUAL TO 4"  WHERE 4"  IS THE PRODUCT OF  PULSEWIDTH AND SWEPT BANDWIDTH 4HE  
 9.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 Of further concern to high precision monopulse applications is drift of the elec - tronic axis that causes variations in phase and temperature variation across the array  surface that causes distortion of the lens. Significant variation of heat distribution  across the array face can result from high power transmitted through the phase shifting  elements as well as the electronic phase control. Consequently, where high precision  tracking is required, special cooling techniques may be necessary to maintain constant  temperature across the aperture. 
 4. The SCR-268 Radar, Electronics, vol. 18, pp. 
 VARYING GAIN APPLIED    IN THE RECEIVER AND SIGNAL PROCESSING  AND TO INTRODUCE SPREADING LOSS AND THEN COM 
 The nature ofsuch targets, their number, and the character ofthe information required about them will depend profoundly onthe function which the radar iscalled upon to perform. For example, the radar altimeter used inaircraft deals with only one target—the surface ofthe earth beneath the planeand offers only onedatum—the minimum distance ofthealtimeter from that target. Aradar system used forcontrol ofairtraffic near alanding field, on the other hand, must display the range, bearing, and altitude ofall aircraft within ornear the boundaries ofthe control zone. 
 The filter needs to provide enough stopband rejection  that any aliased components are insignificant. Of course, practical filters do not have FIGURE 25.6  (a) Non-real signal spectrum before sampling by Nyquist frequency, B, and ( b) signal  spectrum after sampling0B/2 B 2B –B –2B0 B 2B –B –2Bfreq freq(a) (b)B –B/2 FIGURE 25.7  (a) Bandlimited, real passband signal spectrum before sampling and ( b) signal spectrum  after sampling0B/2 B 2B –B –2B0 B 2B –B –2Bfreq freq(a) (b)B/2 B/2 –B/2 ch25.indd   5 12/20/07   1:39:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 229  Filter bank:  CW radar. 76-77  digital, for MTI. 121-125  Fixed error. 
 for a radar operating as shown in Fig. 24.1, there will be a 500-nmi range extent at a 10-kHz resolution bandwidth requiring about 60 range gates; / and Q pro- cessing to expose unambiguously target dopplers between ±wrf/2 requires a sam- ple rate of 40 kHz. For the Fig. 
 ANE-Il, pp. 218-223, December 1964. 11. 
 Thereislittleguidance available onhowtoaccount for theperformance ofanoperator. Basedonbothempirical andexperimental results,onestudy69givestheoperator­ efficiency factoras (2.53). where Pd is tlie single-scan probability of detection. 
 For a ship at broadside, yo  is approximately 0.15 times the ship length.  When angle errors due to glint are large, the received signals are small; that is, the  received signal amplitude and the glint error are negatively correlated. Thus, by transmitting a  number of frequencies and using the angle error corresponding to that frequency with the  largest signal, it is possible to eliminate the large angle errors associated with Those  returns of low amplitude and, hence, of high error, are excluded in this technique. 
 104.1liSAppreciable echoes areobtained onlywheninsectbodylengthsaregreaterthanathirdoftheradarwavelength. Insects observed broadside haveechoes 10to1000timesgreater thanwhenviewed end_on.116 Heavyangelactivitycanbereadilyproduced byinsectconcentrations thatwouldscarcely calisevisualawareness. Insectscanbecarriedbythewind;therefore angelsduetoinsects mightbeexpected tohavethevelocityofthewind.Insectechoesaremorelikelytobefoundal theloweraltitudes, neardawnandtwilight. 
 September,  1963.  100. Crispin, J. 
 February, 1948.  5 1. Baker, C. 
  AND A PROB 
 AP-6.'pp. 1 14- 120, January, 1958.  114. 
 [ CrossRef ] 15. Freeman, A. Calibration of linearly polarized polarimetric SAR data subject to Faraday rotation. 
 8.9 and 8.10 for PD — 0.5 and 0.9, respectively. The binary integrator is used in many radars because (1) it is easily imple- mented, (2) it ignores interference spikes which cause trouble with integrators that directly use signal amplitude, and (3) it works extremely well when the noise has a non-Rayleigh density.19 For Af = 3, comparison of the optimal binary inte- grator (3 out of 3), another binary integration (2 out of 3), and the moving-window detector in log-normal interference (an example of a non-Rayleigh density) is shown in Fig. 8.11. 
 The  designer must then make subjective judgments or even arbitrary choices in order to arrive at  a compromise set of radar characteristics. Logical design of an entire radar system by com-  puter is therefore difficult and dangerous. Experience and educated gilesses are still necessary  in many cases, just as is true of other engineering disciplines in which reasonable design  decisions must be made on the basis of incomplete information or conflicting constraints. 
 A., A. Kozma, J. L. 
 CW radar is also employed for monitorinf  the docking speed of large ships. It has also seen application for intruder alarms and for the  measurement of the velocity of missiles, ammunition, and baseballs.  The principal advantage of a CW doppler radar over other (nonradar) methods of meas­ uring speed is that there need not be any physical contact with the object whose speed is being  measured. 
 #/5.4%2-%!352%3   Ó{°{Ç  ! THIRD  MORE DRASTIC APPROACH  CONSISTS OF DISCARDING THE MEASUREMENT WITH HIGHER  RANGE AMONG THE TWO MEASUREMENTS THAT HAVE EXCEEDED THE DETECTION THRESHOLD OF  MORE THAN  D" )T IS IMPORTANT TO GUARANTEE  UNDER 2'0/  A VERY HIGH 3.2 FOR THE TARGET )N FACT   IT MIGHT HAPPEN THAT THE SIGNAL PRODUCED BY THE FALSE TARGET OVERCOMES THE DETECTION  THRESHOLD WHEREAS THE ONE FROM THE TRUE TARGET DOES NOT  THUS CAUSING AN ASSOCIATION ERROR WITH POSSIBLE SERIOUS CONSEQUENCES IN THE TARGETS TRACKING (ENCE  WHENEVER 2'0/ IS ACTIVE  A HIGH ENERGY WAVEFORM MUST BE SELECTED ! FURTHER PRECAUTION IS THE FOLLOWING IF THERE ARE MISSED DETECTIONS FOR AT LEAST TWO OUT OF THE LAST THREE SCANS  AN  IMMEDIATE REVISIT WITH SAMPLING INTERVAL  4 S    S IN SEARCH DWELL MODE IS PERFORMED  )N SEARCH MODE  THE RANGE GATE IS  KM INSTEAD OF  KM  SO IN THIS WAY  IT IS POSSIBLE  TO OBTAIN A NEW TARGET  MEASUREMENT FOR UPDATING THE TRACKING FI LTER AND THUS AVOID THE  TARGETS LOSS 3IMULATION 2ESULTS  -ONTE #ARLO SIMULATION EXPERIMENTS USING THE BENCHMARK  HAVE BEEN CARRIED OUT IN ORDER TO ASSESS THE BENEFITS OF THE ABOVE DESCRIBED %##-S -ORE SPECIFICALLY  THE ADAPTATION OF THE DETECTION THRESHOLD HAS BEEN USED AS ! 
 F. (ed.): "Prediction of Terrestrial Effects of Solar Activity," National Oceanic and Atmospheric Administration, 1980. 48. 
 Crossrange Resolution.  Let us now assume that the airborne (or spaceborne) SAR  is observing a scene on the Earth’s surface consisting of a few point targets and that it  transmits and receives N identical pulses each of bandwidth B (presumably, though not  necessarily, via the LFM waveform) and determines the downrange position of each  FIGURE 17.1  Range and crossrange resolution: Similar discrete Fourier transform (DFT) processes may  be used to obtain range and crossrange resolution.(a) Do wnrange (b) Cr ossrang e N/(2T) = fR/2Frequenc y Doppler  Frequency fdTimeTime Downrange  Distance dr = (c/2)∆t Velocity v = (l/2)fd Crossrange  Distance r = v/ΩFourier  TransformFourier Tr ansformf0 – B/ 2 f0 + B/ 2 f0 ∆f ≅ B/N ∆t = 1/B dr = c/(2B)–T/2 T/2 0 ∆t ≅ T/N = 1/fR 1/T –fR l/4 fR l/4–N/(2T) = –fR/2 l/(2T)0 0 0 –fR l/(4Ω) fR l/(4Ω) dcr = l/(2ΩT)  = l/(2∆q) ch17.indd   7 12/19/07   2:36:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 n➤Bushing F1~. 1420. -Holtzer-Cabot Electric Company carbon-pile speed governor. 
 The present static accuracy ofairborne gyros ranges from +#to+#. However, errors offrom 1°to5°may occur ifthe erection mechanism isnot cut offinaturn. This error isafunction oftheduration oftheturn. 
 Resolution of the SAR. The beamwidth of a conventional antenna of width D at a wavelength  1 is  Bs = kl/D (14.2)  3 where k is a constant that depends on the shape of the current distribution across the aperture.  (The constant k might vary from 0.9 to 1.3 or greater.) For convenience of analysis, take k = 1. 
 196–204, 1972. 45. P. 
 Typical bandwidths range from 500 Hz to 2 kHz.5 Target acquisition is accomplished by sweeping the frequency of the speedgate LO over the designated portion of the doppler bandwidth. In essence, this sweeps the spectrum past the narrow frequency window of the speedgate. When a signal exceeds the detection threshold, the search is stopped and the sig- nal is examined to verify that it is a coherent target rather than a false alarm due to noise. 
 Ifthetargetaspectchanges with respecttotheradar-as mightoccurbecauseofmotionofthetarget,orturbulence inthecase ofaircrafttargets-the relative phaseandamplitude relationships ofthecontributions from theindividual scatterers alsochange. Consequently, thevectorsum,andtherefore theampli­ tude.changewithchanging targetaspect. Amplitude fluctuations oftheechosignalareimportant inthedesignofthelobe­ switching radarandtheconical-scan radarbutareoflittleconsequence tothemonopulse tracker. 
 3.4 RECEIVERFRONTEND Configuration. The radar front end consists of a bandpass filter or bandpass amplifier followed by a downconverter. The radar frequency is down- converted to an intermediate frequency, where filters with suitable bandpass characteristics are physically realizable. 
 Of course, depending on the angular distribution  of the noise sources, the array response pattern may have very high sidelobes, but they  will lie in directions where the noise levels are lowest. The same may not be true of  the clutter that occupies the low doppler band, [–1,1] Hz, which has not been used to  guide the adaptation of the array response. Indeed, the resultant clutter spectrum may  well have characteristics very different from those found in the steer direction. 
 Evolution of Land Subsidence Figure 5illustrates the spatial distribution of subsidence and its changes over time. In most part of the city, the cumulative subsidence is stable in a range of −15 to 15 mm. But for the four major areas of subsidence, the cumulative subsidence gradually increases over time, and the area is constantly expanding. 
 SIMU LTANEOUS MEASUREMENT  OF MICROWAVE BACKSCATTER AND EMISSIVITY OF LAND AND OCEAN ON A GLOBAL SCALE AND     TO PROVIDE ENGINEERING DATA FOR USE IN DESIGNING SPACE RADAR ALTIMETERS 4HE EQUIP 
 The data - base also includes radar target descriptions and platforms’ EM emitter suites. Figure 26.9 is an illustration of an AREPS four-panel display. This display was  created in support of U.S. 
 Thereareothersignificant differences inEq.(13.8)thatshouldbenoted.Thetransmitter powerdoesnotappearexplicitly. Increasing thetransmitter powerwillindeedincrease the targetsignal,butitwillalsocauseacorresponding increase inclutter.Thusthereisnonetgain inthedetectability ofdesiredtargets.Theonlydemand onthetransmitter poweristhatitbe greatenoughtocausetheclutterpowerattheradarreceiver tobelargecompared toreceiver noise.Ifotherwise, Eq.(13.8)wouldnotapply. Theantenna gaindoesnotenter,exceptasItisaffected bytheazimuth beamwidth0B' Thenarrower thepulsewidththegreatertherange.Thisisjustopposite tothecaseof conventional radardetection oftargetsinnoise.Alongpulseisdesiredwhentheradaris limitedbynoiseinordertoincrease thesignal-to-noise ratio.Whenclutterdominates noise,a longpulsedecreases thesignal-to-clutter ratio.(Whenpulsecompression isused,thepul'ie. 
 It is not enough to match one element in the presence of all its terminated neighbors. The element will deliver power to its neighbors, and this loss in power corresponds to the average power lost when scanning. An ideal although not necessarily realizable element pattern would place all the radiated power into the scan region, giving a pattern like a cosine on a pedestal and thereby providing maximum antenna gain for the number of ele- ments used. 
 Navigation mayalsobeperformed with{)nlytwoantenna beamsifsomeauxiliary means isusedtoobtainathirdcoordinate. Twobeamsgivethetwocomponents oftheaircraft velocity tangent tothesurfaceoftheearth.Athirdcomponent, theverticalvelocity, isneeded andmaybeprovided fromsomenondoppler sourcesuchasabarometric rate-of-c1imb meter. Theprimary advantage ofthetwo-beam systemisareduction inequipment. 
 (a) Overlapping antenna patterns; (b) sum  pattern; (c) dilierence pattern; (d) product (error) signal.  an error signal wllose magnitude is proportional to the angu!ar error and whose sign is  proportional to the direction.  The output of the monopulse radar is used to perform automatic tracking. 
 BIT VALUE THAT REPRESENTS THE  AMPLITUDE OF THE SINE WAVE AT THE INPUT PHASE )F WE REPRESENT THE TUNING WORD BY  -   THE SAMPLE FREQUENCY BY  F S  AND THE NUMBER OF BITS IN THE PHASE ACCUMULATOR BY  N   THEN THE FREQUENCY OF THE OUTPUT SINE WAVE CAN BE EXPRESSED AS -FSN )N THIS SCHEME  THE PHASE REPRESENTED BY THE RUNNING SUM WILL OVERFLOW WHEN IT  CROSSES OVER O 4HE ADVANTAGE OF EXPRESSING THE PHASE IN "!- NOTATION IS THAT IT  ALLOWS MODULO 
 The two-faced  radar uses 1792 active T/R modules per face, and each module interfaces with a dipole  antenna element. Extra elements and a narrow beam are used on receive, and upgrade  capability has been included for the future installation of up to 5354 T/R modules per  array face. The peak power output from each face, when populated with 1792 modules  is 600 kW, and the average power output is 150 kW. 
 Hines, M. E.: Fundamental Limitations in RF Switching and Phase Shifting Using Semiconductor  Diodes, Prois. IEEE, vol. 
 63–77, 1985.  85. J. 
 Delano, R. H., and I. Pfeffer: The Effect of AGC on Radar Tracking Noise, Proc. 
 As the transmitted pulse travels beyond the  ground clutter range (typicaJly 50 miles or greater) the receiver is switched to the lower beam  for long-range reception. In the ARSR-3 the ratio of the lower-beam gain in the direction of  the horizon to that of the upper-beam gain in the same direction is 16 dB.4b (The lower beam  has its half-power point on the horizon.) The antenna elevation pattern is shaped to have at  the higher angles a greater gain than would be normal with a cosecant-squared pattern. This  permits sensitivity time control (STC) to be used with the radar without a loss of coverage at  high altitudes and short range (Fig. 
 With the clutter at DC, the spurious signals  caused by certain receiver nonlinearities, such as mixer intermodulation products and  video harmonics, also fall near DC and can be filtered out along with the main-beam  clutter.19 The frequency shift applied is a function of the antenna main-beam line- of-sight relative to the platform’s velocity vector. This process is known as clutter  positioning . Output Generator. 
 (1 1.16) and (1 1.17) to be Figure 11.5 Shape of rectangiilar pulse  Ti + 3Tl T2 'I2  6T"= ( 6E/No ) trapezoidal pulse \ / after passlng through a band-limited rec-  Time -+ tangular filter.  When the trapezoidal pulse approaches in shape the rectangular pulse, that is, when TI g T2,  Eq. ( 1 1.2 1 ) becomes  The bandwidth B is approximately the reciprocal of the rise time T2, and if TI = r/2, where r is  the pulse width, the rms error is  which is the same as that derived previously for the bandwidth-limited rectangular pulse. 
 Much of the discussion regarding the statistics of  sea clutter applies as well to land clutter, except that the physical mechanisms may be different.  The statistical variation of a0 from homogeneous terrain such as deserts and some types of  farmland can sometimes be described by the gaussian probability density function (pdf ), so  that the envelope of the radar receiver output is given by the Rayleigh pdf (Eq. 13.10).44 Some  urban areas, rural areas with buildings and silos, and mountainous terrain approximate the  log-normal pdf (Eq. 
 WAVELENGTH MONOPULSE CAPABILITY MAY BE EFFEC 
 At frequencies above K, band most microwave techniques are inadequate,  so that new technology is required. Thus K, band should not usually be included as part of  the millimeter-wave region.  Advantages of millimeter waves. 
   PP n  /CTOBER   % & +NOTT  * & 3HAEFFER  AND - 4 4ULEY   2ADAR #ROSS 3ECTION   2ALEIGH  .# 3CI4ECH 0UBLISHING   )NC    P   2 ' (AJOVSKY  ! 0 $EAM  AND ! ( ,A'RONE  h2ADAR REFLECTIONS FROM INSECTS IN THE LOWER  ATMOSPHERE v )%%% 4RANS  VOL !0 
 In the quantum-mechanical case, on the other hand, the observer does not  have controliover his system as does the radar designer since the {3a product of a quantum  particle is fixed by nature and not by the observer.  Angular accuracy. The measurement of angular position is the measurement of the angle of  arrival of the equiphase wavefront of the echo signal. 
 65. Rincliart, R. F.: A Solution to the Problem of Rapid Scanning for Radar Antennas. 
 18.53 . This page has been reformatted by Knovel to provide easier navigation. Contents     xxvii   Range Measurement Errors  ............................... 
 TRONIC EQUIPMENT IS HOUSED IN ONE SHELTER AND THE STANDBY GENERATOR IS HOUSED IN ANOTHER 4!",%  2ELEVANT .EXRAD 3YSTEM #HARACTERISTICS 4RANSMITTED 0EAK!VERAGE 0OWER KLYSTRON   K7   7 0ULSE LENGTH    M    MS  0OLARIZATION ,INEAR HORIZONTAL 7AVELENGTH  CM 2ECEIVER NOISE TEMPERATURE  + $YNAMIC RANGE  D" !NTENNA GAIN  D" "EAMWIDTH n 3IDELOBE LEVELS   n D" -AXIMUM RANGE REFLECTIVITY DATA   KM -AXIMUM RANGE DOPPLER DATA   KM 5NAMBIGUOUS VELOCITY o  MS #LUTTER SUPPRESSION MAXIMUM    D" 3YSTEM SENSITIVITY n D": AT  KM 2OTATION RATE n DEGSEC &)'52%     .EXRAD  732 
 TERER IN ROLLING PITCH  YAW  MOTION AT A HEIGHT   H  IS THE TIME DERIVATIVE OF  2 SHOWN IN  &IGURE  &OR A GIVEN DESIRED CROSS RANGE RESOLUTION WITH REASONABLE SIDELOBES   $RC   A MUST BE EQUAL TO  $RC K &OR THE EXAMPLE   FT CROSS RANGE RESOLUTION IS OBTAINABLE  WITH A  
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar.  TRACKING RADAR  9.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 Another technique is to use a pair of oscillators—one controlling the transmitter  trigger and the other controlling the range gate.24 The range rate is controlled by the  beat frequency between the oscillators, where one is frequency-controlled by the range  FIGURE   9.17  Digital range tracker operation FIGURE   9.18  Block diagram of a digital range trackerSTABLE OSCILLA TOR TRANSMIT RESET PULSEHIGH-SPEED DIGIT AL COUNTER TARGET RANGE REGISTER ERR OR VOLT AGE VIDEO PULSEMAIN GATEEARL Y-LATE GA TE ERR OR DETECT ORVOLT AGE-C ONTR OLLED VARIABLE -FREQUENCY OSCILLA TOR POLARITY SENSING TO CONTR OL UP OR DO WN COUNT MAIN GA TE AND EARL Y- LATE GA TE PULSE GENERA TORTRIGGER PULSE DIGIT AL RANGE READOUTCOINCIDENCE CIRCUIT ch09.indd   23 12/15/07   6:07:26 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Timesidelobes andweighting. Theuniform amplitude ofthelinearFMwaveform resultsina compressed pulseshapeoftheform(sinnBt)/nBt afterpassage through thematched filter,or dispersive delayline,whereBisthespectral bandwidth.24Therearetime,orrange,sidelobes toeithersideofthepeakresponse withthefirst,andlargest,sidelobe -13.2dBdownfromthe peak.Thelargesidelobes areoftenobjectionable sincealargetargetmightmasknearby,smaller targets.Also,near-insidelobes mightattimesbemistaken forseparate targets.Thesesidelobes canbereduced byamplitude weighting ofthereceived-signal spectrum, justasthespatial sidelobes ofanantenna radiation patterncanbereduced byamplitude weightiflj theillumina­ tionacrosstheantenna aperture, aswasdescribed inSec.7.2.Thesameilluminalion funclions usedinantenna designtoreducespatialsidelobes canalsobeappliedtothefrequency domain toreducethetimesidelobes inpulsecompression. Acomparison ofseveraltypesofspectraI weighting functions isshowninTableILL16,24.25TheTaylorweighting withiI=8meansthe peaksofthefirst7sidelobes (i1-1)aredesigned tobeequal,afterwhichtheyfallofTaslit. 
 Hardange, J. Marchais, and E. Normant, Air and Spaceborne Radar Systems: An  Introduction,  Norwich, NY: William Andrew Publishing, LLC, 2001, pp. 
 Homing onaSwjace Target.—The simpler ofthetwo problems isthat ofthe detection and interception ofshipping bypatrol aircraft. Since targets areknown tobeonthe surface ofthe sea, homing information need besupplied only inazimuth. The first operationally successful aircraft-to-surface-vessel, ASV, radar was theBritish ASV lMark II. 
 3HALOM AND % 4SE  h4RACKING IN A CLUTTERED ENVIRONM ENT  WITH PROBABILISTIC DATA ASSOCIA 
   -ASSACHUSETTS )NSTITUTE OF 4ECHNOLOGY  ,INCOLN ,ABORATORY  .OVEMBER     - $ !BOUZAHRA AND 2 +  !VENT  h4HE  
 If it is known that the instabilities are random, the peak  ch02.indd   71 12/20/07   1:46:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 For example,  an over-the-horizon (OTH) radar can have a site separation of 100 km or more to  achieve adequate transmit signal isolation. But that separation is small compared to  the target range of thousands of kilometers, and the radar again operates with mono - static characteristics. A variation of the bistatic radar is the multistatic radar , which uses multiple anten - nas at separate locations, one antenna for transmission and multiple antennas—each  at a different location—for reception, or vice versa. 
 N For microwave radar most land areas are wholly onthe rough side ofthedivision between rough and smooth surfaces-primarily because of the presence ofvegetation, Because the ground isthoroughly rough, theaspect function F(fI) ofSec. 3.11 takes, forground return, thefollow- in~simple form: F(6) =Ksin0, (32). 94 PROPERTIES OF RADAR TARGETS [SEC. 
 NOISE AMPLIFIER ON RECEIVE 4HIS IS NOT THE CASE WITH MOST FERRITE DEVICES &ERRITE  0HASE  3HIFTERS  -OST FERRITE PHASE SHIFTERS ARE NONRECIPROCAL  n  AND THEIR EARLY VERSIONS USED DISCRETE LENGTHS OF FERRITE AS SHOWN IN &IGURE   TO IMPLEMENT EACH OF THE BITS  n  n  n  ETC  )N THIS CONFIGURATION  A CUR 
 Beard.C.I.:Coherent andIncoherent Scattering ofMicrowaves fromtheOcean,IRETrailS.• vol.AP-9,pp.470-483, Sept.,1961. Beard.C.I.,D.L.Drake,andC.M.Morrow: Measurements ofMicrowave Forward Scattering from theOceanatL-Band. IEEENAECON '74Record,pp.269-274,1974. 
 Theshapeofthebeamattheotherangular positions isthe projection ofthecircular beamshapeonthesurfaceoftheunitsphere.Itcanbeseenthatas thehcarnisscanned intheVdirection, itbroadens inthatdirection, butisconstant inthe1> direction. For()¥-O.thebeamshapeisnotsymmetrical aboutthecenterofthebeam,butis eccentric. Thusthebeamdirection isslightly different fromthatcomputed bystandard for­ lIIulas.Inaddition tothechanges intheshapeofthemainbeam.thesidelobesalsochangein appearance andposition. 
 E.: Note on complementary series, Proc. IRE, vol. 50, p. 
 FED SERIES L LGrBEAMWIDTH L LGrBEAMWIDTH 3PACE 
 Inthesame way Sweep 2isdelayed and subtracted from Sweep 3,and soon. The results areshown inthelast three traces ofFig. 16.7. 
 The sq&;t mode produces a strip map just as does the sidelooking SAR. Thc doppler  heum-slrarpettitry mode is used with a circularly scanning antenna and a normal PPI display. As  the squint angle of the doppler beam-sharpening mode varies, thc integration time d..:h:~nges to  keep tlie resolution constant.' The along-track resolution for either the squint mod(. 
 Input output  hybrid  junction  1 SIIO~I c~rcuits Figure 8.7 Hybrid-coupled phase bit.  tile sign:ils will be reflected by the short circuits located farther down the transmission lines.  'I'llc sigrlals at ports 2 and 3, after reflection from either tlie diode switches or tlie s1101.t  circuits. 
 Thenatureofthe surfaceroughness canbeinferred fromtheradarecho,ascanthedielectric properties ofthe scattering surface.Theformerhasbeenappliedtothemeasurement ofseastate(fromsatel­ lites),andthelatterwasusedinearlyradarastronomy toprobethenatureofthemoon's surface. 11.3THEORETICAL ACCURACY OFRADAR MEASUREMENTS Theabilityofaradartodetectthepresence ofanechosignalisfundamentally limitedbynoise. Likewise, noiseisthefactorthatlimitstheaccuracy withwhichtheradarsignalsmaybe estimated. 
 TO 
 Echoes from the various sources of clutter  experienced by a civil-marine radar might be 80 dB greater than receiver noise, yet the receiver  might only be able to display without saturation signals that are less than about 20 to 25 dB  above noise.22 Sensitivity time control (STC), or swept gain, is widely used to reduce the  large echoes from close-in clutter. STC is a time variation of the receiver gain. At the end of  the transmission of the radar pulse the receiver gain is made low so that large signals from  nearby clutter are attenuated. 
  +1 
 An early model of a Raytheon reflectarray gave an ellipticity ratio of less than 1.5 dB with scans up to 30°, corresponding to a theoretical rain rejection of at least 15 dB. At the same time, an aircraft target would typically lose approximately 3 dB, leaving a relative net improvement of 12 dB of rain rejection. Phased Arrays with Very Wide Bandwidth. 
 The TWT usually has slightly less gain than a klystron and less stability. It should be  noted, however, that as the power of a TWT increases, its bandwidth decreases; and as  the power of a klystron amplifier increases, its bandwidth increases. Thus, at the high  powers needed for many radar applications, the bandwidths of these two types of linear- beam tubes are approximately comparable. 
 176.-Phase-shift data transmission using two c-w subcarriers. severe requirements onthe audio filters. Because oftheir harmonic relationship, thesinusoids must bekept extremely pure, and furthermore any relative phase shifts introduced bythefilters (orother circuit com- ponents) must beextremely constant with time. 
 60 TIIERADAR EQUATION [SEC. 2.15 wtivelengths, incontrast tothe behavior ofthe water-vapor curve, a residual absorption persists uptowavelengths ofthe order of30cm. This effect issmall enough tohave escaped experimental detection, butitis clearly predicted bythetheory.’ Except near thecenter ofthe absorption maximum, theattenuation due tooxygen should vary about asthe s~uare ofthe pressure; hence the effect rapidly diminishes at high altitudes. 
 Figure 14. The residual spatial variance of the Doppler parameters after compensation based on the estimation results of the EMAM method. 65. 
 The log-FTC, or similar CF AR, is necessary, however, in order to extract the target informa­ tion contained in the radar signal that otherwise would be undetected if displayed along with  the clutter, or which would be lost because of computer overload in an automatic system.  Although one of the first applications considered for the log-FTC receiver was the detec-. RADAR CLUTTER 507  tion of targets in sea clutter.RR.HQ it is probably more useful for operation in precipitation  clutter. 
 Sometimes anR-sweep and anA-sweep are shown simultaneously onthe same tube byswitching between them onalternate pulses. The A-sweep isused forgeneral surveillance oftargets and fordetermining @Q@ (a)R-scope with marker (b)R-scope with step (c)R-scope with notch. pip. 
 Res ., vol. 93, pp. 3642–3648, April 15, 1988. 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 and  s t a j j r t t2 2 2 1 ( ) exp[ ( , )] = − + − Γ ∆ ϕ ϕ (18.11) where the subscripts on the reflectivity Γ suggest that the two signals may be obtained  at two different points in time as well as from two different spatial perspectives. The  objective is to estimate the relative phase difference ∆j, usually found through the  cross-correlation  E s t s t R t t a j r t t [ ( ) ( )] ( , ) exp[ ( ,1 1 2 2 12 1 2 2 1 = − − ∆ϕ ) )] (18.12) which is presented as it would be calculated using complex image data. 
 1Theword impedance, asused inthissection, means thevoltage-current ratio ofa magnetron attheoperating point. Thedynamic impedance, theslope ofthevoltage- current curve near theoperating point, isvery much lower, usually around 100ohms. SeeSec. 
 13.2) into two parts, the blue component being inthetube and thepersistent component onthe projection screen. Although this scheme isbetter than direct projection ofacascade screen, results are farfrom satisfactory.. 220 2. 
  D6 1    3UBSTITUTION OF %QS  AND  INTO %Q  YIELDS THE AMPLITUDES OF THE SPECTRAL  COMPONENTS LISTED IN 4ABLE  .OTE THAT IF THE NONLINEARITIES  IN ) AND 1 WERE IDENTI 
 There were separate transmit and receive antenn as, which were simple dipoles. There were two antennas for transmission and two for reception, mounted on either side of the aircraft, as shown in ﬁgure 2.1. Transmission and reception alternated between left and right hand sides and returns were shown on an A-scope display indicating the direction of the target from the relative power of the returns in the left and right antennas. 
 OFF BETWEEN HARDWARE COMPLEXITY  COST  AND ACHIEVABLE PERFORMANCE. 
 Both AREPS and APM are  accredited within the Navy Modeling and Simulation Office (NMSO). AREPS is also  a North Atlantic Treaty Organization (NATO) application, approved by the Military  Committee Meteorological Group/Working Group, Battle Area Meteorological  Systems and Support plus with Partners. AREPS version 3.6 contains several EM propagation models for applications at  various frequencies. 
 Below 50 metres the aerial and line must be shorter, but are still not a cause of serious loss until we reach about iO metres. (See (a).) For wavelengths from about § metre to, say, IO metres the transmission line (6) must be suitably chosen. transmission lines are made of concentric cable as suggested in (ce), in order to cut down attenuation losses. 
  NOSE 
 14.19. The reactor and condenser connected inseries with the rectifier which energizes the regulating field are designed to resonate atafrequency well above therated frequency ofthealternator (inthis case, 400 cps). The circuit therefore operates onthe low- frequency side oftheresonance curve; any change inspeed will alter the reactance ofthe circuit and thus vary the field current inthe correct direction toprovide speed regulation. 
 The accuracy of this estimator is given in Fig. 8.7 for the case of n = 2 pulses per beamwidth. This estimation procedure can also be used to estimate the elevation angle of a target in multibeam systems where O1 and 02 are the elevation-pointing angles of adja- cent beams.NO FADING Pfa = 10-6RELATIVE ANGULAR ACCURACY (ae\ e3dB) . 
 110INTRODUCTION TORADAR SYSTEMS Clutter fOldover~ /'"I "-/ \ / \ / \ / \ / \ / \ tp=Yr FrequencySingle concellotionClutter spectrum /' I I / /Double \ /concellotion--"'" I \ I \1.0 <I.l ~0.8 o0.:a0.6 L.. .~0.4­o£0.2 O~L- l- ~II'l.a:~--_L-_-_.rLAJ/Lll.:..:L-- o Figure4.10Relative frequency response ofthesingle-delay-line canceler (solidcurve)al}dthedouble­ delay-line canceler (dashedcurve).Shadedarearepresents clutterspectrum. whichisthesameastheoutputfromthedouble-delay-line canceler. 
 It was usually installed with a switch to turn it off, if  necessary. Today Dicke-Fix is not used in a modern radar, especially one that employs  doppler processing; thus, it is no longer of interest in many radar applications. Other special processing circuits can be used in the radar to avoid saturation, i.e.,  fast-time-constant (FTC) devices (perhaps of little use in modern radar), automatic  gain control (AGC), and CFAR.8,29,31 However, they cannot be said to be ECCM tech - niques. 
 OUS DOPPLER CLUTTER AND THE SECOND WITH UNAMBIGUOUS DOPPLER CLUTTER  ARE SHOWN IN &IGURE  4HE FIGURE SHOWS THOSE ANTENNA ANGLES WHERE THE CLUTTER DOPPLER RESPONSE REMAINS AFTER FILTERING THROUGH A SINGLE DOPPLER FILTER &IGURE  A SHOWS THE RESPONSE  FOR AN AMBIGUOUS 02& OF  (Z  AND &IGURE  B SHOWS THE RESPONSE FOR AN UNAM 
 Figure 25.23 shows a block diagram of this  technique, in which a numerically controlled oscillator (NCO) generates a digitized  sinusoid that is converted to an analog signal by a digital-to-analog converter (DAC).  Figure 25.24 demonstrates how an NCO operates to produce a sine wave. The n-bit  tuning word is actually a phase increment that determines the frequency of the sine  wave output. 
 Determination of the appropriate numbers to use for these quantities in their respective equations is a basic problem of radar range prediction. As will be seen, one of the problems is to define the meaning of de- tectable.BTDETECTABILITY FACTOR DQOO) (DECIBELS) . Integration of Signals. 
 BORNE THREAT IS THE ANTI 
 Cost, “Measurements of the bistatic echo area of terrain at X-band,” The Ohio State  University, Antenna Laboratory, Report No. 1822-2, May 1965.  91. 
 Spatial Diversity.  The rationale is to use two low-gain auxiliaries (instead of one,  as shown in Figure 24.4) for the SLB; because their phase centers will be different, the  grating lobes affecting the adapted patterns of the two SLB antennas will be different  too. Taking the greater of the two adapted SLB signals, the gain margin between the  SLB and the main antenna sidelobes will increase with a consequent improvement of  the performance of the blanking logic.FIGURE 24.4  A processing scheme incorporating SLC and SLB devicesRX & ADC xRX & ADC +W1xW2 +RX & ADCAuxiliar y channelMain channelSLB channel MAIN ' SLB' Gate Compar isonMAIN ' SLB' Blanking of adapted main signal range cellMAIN ' SLB' >FF blanking thresholdTo target detectionSLB SLC MAIN x 1 x 1 ch24.indd   18 12/21/07   10:51:26 AMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The DAS combines data from each site non- coherently; the DAR, coherently. Bistatic radars have been analyzed, proposed, and in some cases developed for other than military applications. Such applications include high-resolution im- aging at short ranges (in the near field of the antennas) for use by robotics in an industrial environment;62 airport ground vehicle and aircraft collision warning . 
 14. Vendor transistor datasheet, Philips , www.datasheetcatalog.com. 15. 
 OF 
 , vol. AP-8, pp. 246–254, 1960. 
 A. Acker,40 “these are periodic instabilities that can occur in the electron beam  at video frequencies, resulting in signals other than the carrier frequency, causing  severe problems to doppler radar performance.” Acker also states that ion oscillations  require a finite time to develop so that if a tube is operated with less than a 10 µs pulse  width, ion noise is usually not of concern. Advances in digital technology have allowed a method to reduce intra-pulse trans - mitter noise and power supply instabilities that affect radar performance by the presence  of strong clutter echoes. 
      F FVIB      )N  THE 3!2 IMAGE  THE VIBRATING POINT TARGET WILL APPEAR IN THREE CROSSRANGE LOCATIONS  -OST OF THE TARGET ENERGY STILL APPEARS AT THE CORRECT LOCATION  WHEREAS A SMALL FRACTION  OF THE ENERGY WILL APPEAR IN EACH OF TWO PIXELS SEPARATED IN CROSSRANGE BY  FVIB IN DOPPLER  FREQUENCY 4HUS  A VIBRATING TARGET CAN GIVE RISE TO A PAIR OF DISTINCTIVE ECHOES&)'52%   )MAGING A MOVING TARGET IN A 3!2 IMAGE  A  #ONVENTIONAL 3!2 IMAGE REAL DATA  SHOWING  BLURRED MOVING VEHICLES AN - MILITARY TRUCK  A TRACTOR 
 CAVITY KLYSTRON  STATES THAT ONE OF THESE WIDE BANDWIDTH TUBES CAN BE USED TO REPLACE THE TWO NARROWER 
 FILTER MAP 2&-  OF MAIN BEAM AND 3," CHANNELS 4HE 2&- IS A TWO 
 The noise temperature  ratio of a crystal mixer varies approximately inversely with frequency from about 100 kHz (the  exact value depends upon the diode25) down to a small fraction of a hertz. This is calledflicker  (9.11)RECEIVERS, DISPLA V5,ANDDUPLEXERS 347 J11makingameasurement ofthereceivernoise-figure, thenoisesourceorsignalgenerator isusuallyinserted byadirectional coupleraheadoftheduplexer andotherRFcomponents so thattheoverallnoise-figure ofthesystemismeasured ratherthanthatofthereceiver alone. 9.31\lIXERS Manyradarsuperheterodyne receivers donotemploy alow-noise RFamplifier. 
 Space-fed arrays are generally cheaper than conventional arrays because of the omission of  the transmission-line feed networks and the use of a single transmitter and receiver rather than  a distributed transmitter and receiver at each element. A space-fed array may be simpler than  an array with a constrained feed, but a sacrifice is made in the control of the aperture  illuminationi'and in the maximum power capability of the array. Thus the ability to radiate  large power by using a transmitter at each element is lost in this configuration. 
 Plant, “Bragg scattering of electromagnetic waves from the air/sea interface,” in  Surface Waves and Fluxes: Current Theory and Remote Sensing , chap. 12, G. L. 
 79. W. Alpers and I. 
 ON ASPECT ANGLE FOR WHICH THE IMAGE DATA WERE COLLECTED  THE LEADING EDGES OF THE WINGS ARE VIRTUALLY INVISIBLE (OWEVER  NOTE A FEW ECHO SOURCES ALONG A LINE PARALLEL TO  AND SLIGHTLY FORWARD OF  THE WING TRAILING EDGES )F THE TARGET ROTATION HAD BEEN CENTERED ON AN ASPECT ANGLE PERPENDICULAR TO ONE OF THE WINGS  THE LEADING EDGE OF THAT ONE WING WOULD HAVE hLIT UPv )N THE REGION OF THE MAIN WING ROOTS  WE SEE HEAVY CONCENTRATIONS OF ECHO SOURCES  3OME OF THEM LIE FORWARD OF ANY WING SURFACE !LTHOUGH WE MAY CONCEIVE OF APPARENT SOURCES BEING STRUNG OUT BEHIND ANY PHYSICAL SCATTERING OBSTACLE DUE TO TIME DELAYS OF MULTIPLE REFLECTIONS  IT IS HARD TO RECONCILE THEM BEING STRUNG OUT  IN FRONT OF THE BODY  7E DO SEE SEVERAL CLUSTERS OF APPARENT SCATTERING CENTERS POSITIONED AFT OF THE TAIL OF THE AIRCRAFT  BUT LACKING ANY DETAILED DESCRIPTION OF THE TEST OBJECT  WE CANNOT INTERPRET THEIR MEANING 4HESE hGHOSTv SCATTERERS OWE THEIR EXISTENCE TO THE WAY IN WHICH THE DATA 
 # OPERATION IS A SELF 
 Appl. Comput. Harmon. 
 Low scattering coefficient values can also arise because the angular spectrum of  the wave system is not being sampled along a direction that presents the maximum  amplitude component at the Bragg resonant wavenumber. The directional wave spec - trum can be written as  S k S k F k G k ( ) ( ,) ( ).( ,) ≡ =f f  (20.11) where F (k) is the nondirectional spectrum,  F k S k d ( ) ( ,) =∫f f 02π  ch20.indd   35 12/20/07   1:16:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 In operation, suitable commands were pre - loaded into the onboard SAR control processor for each three-day mapping interval. In order to offset the tenfold altitude change on SAR image quality, the SAR oper - ating profile was designed to exploit a variety of incident angles. At the start of each  imaging pass at high altitude, the incidence was slewed from steep near the pole,  to shallow in the neighborhood of the equator, back to steep when approaching the  opposite pole. 
 17. J. B. 
 226, April 1943 (TNA AIR 15/126) [15] Use of Vixen Equipment with Mark II ASV, CCDU Trial Report 43/31, 2 July 1943 (TNA AIR 65/31)Airborne Maritime Surveillance Radar, Volume 1 2-25. IOP Concise Physics Airborne Maritime Surveillance Radar, Volume 1 British ASV radars in WWII 1939–1945 Simon Watts Chapter 3 ASV Mk. III 3.1 Operational requirement for ASV in October 1942 The operational requirements for ASV were continually evolving to meet the changing threat. 
 RATED  THE ENERGY COUPLED BETWEEN THEM IS SMALL AND THE INFLUENCE OF ONE ANTENNA ON  THE CURRENT EXCITATION AND PATTERN OF THE OTHER ANTENNA IS NEGLIGIBLE !S THE ANTENNAS ARE BROUGHT CLOSER TOGETHER  THE COUPLING BETWEEN THEM INCREASES )N GENERAL  THE MAG 
 However, within the integrating time, moving targets will get defocused, and this is inevitable especially when imaging the ocean surface. Therefore, under a higher radar frequency, the SAR image of the eddy suffers less from defocusing due to a shorter integrating time, the spirals are more obvious and the brightness contrast is larger. However, many additional multi-frequency radar images of shear-wave-generated eddies will be needed for a validation of this conclusion, in our opinion. 
 It will be assumed that the phase distribution  across the aperture is constant and only the effects of the amplitude distribution need be  considered.  The inverse Fourier transform gives the electric field intensity when the phase and ampli-  tude of the distribution across the aperture are known. The aperture is defined as the projec-  tion of the antenna on a plane perpendicular to the direction of propagation. 
 I EE£, vol. 58,  pp. 543-550, April, 1970. 
 The received power isamaximum only when theinterrogator isreally looking atthe beacon. Similarly GEi, the gain ofthe beacon receiving antenna, isa variable depending ontheorientation oftheantenna with respect tothe line from the beacon totheinterrogator. Let usconsider, asanexample, aground radar setscanning around through the complete azimuth circle and interrogating anairborne bea- con. 
 TO 
 Itshouldprovide thenecessary dataforpiloting theaircraft fromoneposition toanother without theneedofnavigation information transmitted totheaircraftfromagrour:dstation Onemethod ofobtaining aself-contained aircraft navigation systemisbase.d 01theCW doppler-radar principle. Doppler radarcanprovide thedriftangleandtruespe.dofthe aircraftrelativetotheearth.Thedriftangleistheanglebetween thehorizontal projection of thecenterline oftheaircraft(heading) andthehorizontal component oftheaircraftvelocity vector(ground track).Fromtheground-speed anddrift-angle measurements, theaircraft's presentposition canbecomputed bydeadreckoning. Anaircraftwithadoppler radarwhoseantenna beamisdirected atanangle)'tothe horizontal (Fig.3.19a)willreceiveadoppler-shifted echosignalfromtheground.Theshiftin ~-------,------~ v /. 
 WIDTH TO COUNTERACT JAMMING  BUT AT THE COST OF INCREASED SIGNAL PROCESSING !N IMPORTANT ADVANTAGE OF TRANSISTORS IS THEIR POTENTIAL FOR WIDE BANDWIDTH &)'52%   4YPICAL SOLID 
 72. flansen, V. G., and A. 
 SPEED PROCESSORS  ALLOWS THE USE OF DYNAMIC SPACE 
 The VA-812E, which  was also derived from the same family as the VA-812C, has a peak power of 20 MW with an  instantaneous 1-dB bandwidth of 25 MHz and a 40 dB gain. Its average power rating is  300 kW at a duty of 0.015 and a 40 µs pulse width. 206 INTRODUCTION TO RADAR SYSTEMS  6.4 TRAVELING-WA VE-TUBE AMPLIFIER  The traveling wave tube (TWT) is another exam pk of a linear-beam, or 0-type, tuhc. 
 OF 
 In this average-power formulation, the av- erage power Pt is multiplied by the integration time tf (assumed to be long com- pared with the interpulse period) to obtain the transmitted energy. Then the value of D0 used is that which would apply if detection were based on observation of a single pulse. (See Sec. 
 The reasons for the differences between the spectra for the two  polarizations are not as yet clear, although the tendency of the H-polarization spectra  to lie at a higher frequency is likely due to the preferential source of H-polarization  returns in faster-moving wave structures.45,64 The (half-power) width  ∆ of the clutter velocity  spectrum is quite variable,  depending on such things as radar polarization and sea conditions. It seems most  closely related to the peak orbital velocity given by Eq. 15.10. 
 Tlie fo~.riier is called an incoherent (envelope) receiver or direct  pliotodetcction. -Plic Inttcr is called a coherent (heterodyne) receiver or photomixer. Wlieri tlie  background noise is low and for short-pulse modulation the laser envelope detector can  operate :IS a qt~arit~~rn-litnitcd device and give essentially the same detectitlity (inverse of the  noise equivalent power) as heterodyne  detector^.^^ (This is unlike microwaves where the video  detector is far less sensitive.) Tlie heterodyne, or photomixing, receiver can have a narrow  passbarid arid significantly reduce tlie effects of background noise. 
 50. E. F. 
 The dopplcr frequency associated with a point Pon the body located a  distance r from the axis of rotation is  . 2 r cos ex 2(1), r cos ex 2w, x Id = --· --------·· = ------ = · A l l ( 14.20)  where r = velocity of point P. From this equation, the resolution in the x dimension can be  written  . 
 RF Head.  The RF head normally comprises the transmitter and the receiver  down to IF or digital baseband, as well as the antenna and turning gear. Its design  for both magnetron-based SOLAS and non-SOLAS radars follows conventional prin - ciples. 
 SNR increases approximately as        . • Coherent integration (predetection integration ): performed before the  envelope detector (phase information must be available).  Coherent pulses must be transmitted. 
 -ULTISENSOR  4RACKING !PPLICATIONS AND !DVANCES   6OL )))  "OSTON !RTECH (OUSE    * / #OLEMAN  h$ISCRIMINANTS FOR ASSIGNING PASSIVE BEARING OBSERVATIONS TO RADAR TARGETS v IN  )%%% )NT 2ADAR #ONF  7ASHINGTON  $#    PP n  ' 6 4RUNK AND * $ 7ILSON  h!SSOCIATION OF $& BEARING MEASUREMENTS WITH RADAR TRACKS v  )%%%  4RANS  VOL !%3 
 The  effects of illumination function and errors are discussed below. Illumination Functions.  The relation between aperture illumination and the  far-field pattern has been studied extensively and is well documented in the litera - ture.65–68 For a continuous aperture, the far-field pattern is the Fourier transform of  the distribution across the aperture. 
 This is a lossless network which  utilizes J-dB directional couplers, or hybrid junctions. along with fixed phased shifters, to form  N contiguous beams from an N-element array, where N is an integer that is expressed as some  power of 2, that is. N = 2r. 
 A plot of the maximum and minimum cosmic-noise  briglitness temperature as a function of frequency is shown by the dashed curves of Fig. 12.11.  The brightness temperature of an extended source of radiation is the temperature of a black­ body which yields the same noise power at the receiver. 
 They canbeburned outeasily atthetime ofinstal- lation byanaccidental discharge ofstatic electricity through them. TAJWB 11.2.—SPECIFICATIONS OF CONVERTER-TYPE CRYSTALS TypeWavelength Conversion Noise tempera- Burnout band (cm) ]0SS(db) ture (times) test(ergs) 1N21B 8-11 6.5 2,0 2.0 1N23B 3.1-3.5 6.5 2.7 0.3 1N26 1.25 8.5 2.5 0,1 11.7. The LocaI Oscillator.-Reflex klystrons are, with very few exceptions, used aslocal oscillators inmicrowave receivers. 
 Based on both empirical and experimental results, one study69 gives the operator­ efficiency factor as  (2.53) . THE RADAR EQUATION 61  where Pd is the single-scan probability of detection. This was said to apply to a good operator  viewing a PPI under good conditions. 
 A small complication is introduced by the presence of  the aerial switch, but in high-frequency radar technique  we have found several comparatively simple ways of  effecting such a rapid switching, and there is, of course,  much saving in space and weight by using a joint aerial  for transmission and reception (or ‘common T and R,’  as the system is generally termed), as well as greater  accuracy in display, because no discrepancy can arise  such as might be the case if we had a separate aerial for  T and R and they failed to move exactly in step while  scanning the skies.  But, whether separate or common T and R aerial  arrays, we must link the system with the transmitter and  receiver. In ships and aircraft it is obviously very diff-  cult to have high-voltage power units, complicated  modulators, and high-frequency apparatus anywhere  near the aerial. 
 The procedure is clearly demonstrated in Figure 8.19.   The transmitting pulse, which is represented by a rectangle in Figure 8.19a is, as shown in  Figure 8.19b, linearly frequency modulated between f 1 and f2.  Figure 8.19c illustrates the time  procedure. 
 The greater the number of  resonators the more difficult the problem of mode separation. Since the mode separation in a  coaxial magnetron is controlled in the TE011 stabilizing cavity rather than in the resonator  area, the coaxial magnetron can operate stably with a large number of cavities. This allows a  larger anode and cathode structure than with the conventional magnetron, and therefore  a coaxial magnetron can operate at higher power levels. 
 J. W. Rogers, L. 
 THE NATURE OF RADAR 7  to the operator. These operations of an ADT are usually implemented with digital computer  techriology.  A common form of radar antenna is a reflector with a parabolic shape, fed (illuminated)  from a point source at its focus. 
 3.6. Third Experiment: Dataset Using Other Models In the third experiment, we used other models compared with Resnet-50 models in the D3 dataset. The results are summarized in Table 7. 
 GRS-30, pp. 630–633, May 1992. ch01.indd   24 11/30/07   4:34:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 EST IN PLANE  WHERE  E   n  AND OUT OF  PLANE  WHERE  E   n 7HEN  E   n   A   \PS  
 inthe opposite direction, the grid isdriven negative, and the process repeats. The period oftheoscillation isprimarily determined byRC,but theother circuit parameters doenter. Characteristics ofthetube itself enter tosuch anextent that thedevice cannot beconsidered asaprecision oscillator, although itcan besynchronized byone ofhigher frequency. 
 S. R. Cloude and E. 
 IZATIONS AND DESIGN CONSTRAINTS v IN TH )NT #ONF ON 2ADAR -ETEOROL !-3    PP *n*   .ATIONAL 2ESEARCH #OUNCIL   !SSESSMENT OF .EXRAD #OVERAGE AND !SSOCIATED 7EATHER 3ERVICES    7ASHINGTON  $# .ATIONAL !CADEMY 0RESS     ( 7 "AYNTON  2 * 3ERAFIN  # , &RUSH  ' 2 'RAY  0 6  (OBBS  2 ! (OUZE  *R  AND * $  ,OCATELLI  h2EAL 
 For horizontal polarization &B° is typically 1 to 5 dB lower, but this difference is not significant compared with the data spread. Measured cross-polarized (VH) values for <JBQ are 10 to 15 dB lower than those for copolarized (W) values at 0, < 1° but only 5 to 8 dB lower at 0, = 3°.43 Out-of-Plane Scattering Coefficient. Limited out-of-plane land clutter measurements have been taken.42'111'112'115 The Cost42 and Ulaby115 data shows reasonable correlation but only limited correlation with the Larson111'112 data. 
 In an amplifier chain type of transmitter, the frequency accuracy is essentially equal to that of its low-level stable crystal (or other) oscillator. Furthermore, the frequency of the amplifier chain can be changed instantaneously by electronic switching among several oscillators, at a rate faster than that of any mechanical tuner. Coherence. 
 The element spacing is generally taken to be a llalf wave-length. If ttlc  elemerlts were not isotropic but had a pattern Ee(8), and if the desired overall pattern were  derloted E,(8), the pattern to be found by synthesis using techniques derived for. isotropic  elements would be given by E,(B)/E,(B). 
 Synthetic Aperture Radar (SAR) is capable of acquiring high-resolution images all-day and in all weather, and it is sensitive to minor changes of ocean surface roughness produced by eddies. Therefore, SAR images are advantageous in the identiﬁcation and study of oceanic eddies. At present, SAR images are widely used for the detection [ 1–5] and statistical research [ 6–8] of oceanic eddies. 
           3INCE  THE MAXIMUM LIKELIHOOD ESTIMATION PROCEDURE TENDS TO REQUIRE A TEDIOUS  COMPUTATIONAL BURDEN  A SIMPLIFIED APPROACH FOR ESTIMATING THE DOPPLER FREQUENCY IS  HIGHLY DESIRABLE /NE SUCH APPROACH USING PHASE MEASUREMENTS OF THE DOPPLER FILTER OUTPUT AT TIMES SEPARATED BY ONE INTERPULSE PERIOD   WAS PRESENTED IN -C-AHON AND  "ARRETT 4HE NORMALIZED DOPPLER FREQUENCY ESTIMATE IS  FDI I I     02& 
 The incident polarization and the direction of the  incident wave were both in the plane of the plate. Nose-on incidence lies at zero- degree aspect at the center of the chart, and the tail-on aspect lies at 180 ° at both  sides of the chart. As shown in Table 14.1, the approximate RCS of a straight edge of length L pre- sented perpendicular to the incident wave is s = L2/p. 
 L. J. Cote et al., “The directional spectrum of a wind-generated sea as determined from data  obtained by the stereo wave observation project,” New York University Meterorol. 
 SIDED BANDWIDTH  " AND COMPOSED OF POSITIVE 
 LATION MUST BE OBTAINED AS THE CONVOLUTION OF THE INDIVIDUAL SPECTRA 7HEN BOTH SPECTRA  ARE GAUSSIAN IN SHAPE  THE RESULTING SPECTRUM REMAINS GAUSSIAN WITH A STANDARD DEVIATION THAT IS THE SQUARE 
 Equation (14.32) may be written  The above equation locates the target in the plane of the angle $,. The location of the target in  the third dimension is found from the measurement of the orthogonal angle coordinate 11/,  (not shown in Fig. 14.12). 
 J. Porcello, R. L. 
 Screens ofvarious rates ofdecay areavail- able forthis purpose. The detailed characteristics ofthetubes, including thescreens, will bediscussed inSees. 13.1 to133.. 
 ZON IS APPROXIMATELY AT THE MAXIMUM RANGE OF INTEREST 4HIS RESULTS IN SEA OR GROUND CLUTTER BEING PRESENT AT ALL RANGES OF INTEREST /THER CLUTTER SOURCES SUCH AS RAIN AND CHAFF MAY COEXIST WITH THE SURFACE CLUTTER )N MOST INSTANCES   THESE SOURCES ARE MOV 
 ·  .1.l <,clnovatch. V. (i.: ;\ Review or Microwave Transistors for Radar Application, NEREM Rec., 1974,  pt. 
 35. C. A. 
 1.2. For most common types of  radar targets such as aircraft, ships, and terrain, the radar cross section does not necessarily  bear a simple relationship to the physical area, except that the larger the target size, the larger  the cross section is likely to be.  Scattering and diffraction are variations of the same physical process.15 When an object  scatters an electromagnetic wave, the scattered field is defined as the difference between the  total field in the presence of the object and the field that would exist if the object were absent  (but with the sources unchanged). 
 Symp. Rec ., September 1968. 12. 
 Note that this signal does not possess complex-conjugate spectral  symmetry. The signal spectrum after sampling by its Nyquist frequency  B is shown in  Figure 25.6 b. There is no aliasing. 
 7.26b is shown as a uniform beam over the  range O s O s 00 and decreases as csc2 0/csc2 00 over the range 00 < (J s Om. The gain G of the  square beam in Fig. 7.26a divided by the gain G, of the cosecant-squared antenna beam in  Fig. 
 41. W. M. 
 Soumekh, M. Synthetic Aperture Radar Signal Processing with MATLAB Algorithms ; Wiley: New York, NY, USA, 1999. 3. 
 RANGE RECEPTION  AND  THEN LOWERED TO HORIZON FOR LONG RANGE  -4$ TECHNIQUES USING CLUTTER MAPS !LSO COUNTING DETECTIONS IN SMALL RANGE 
 drafted the manuscript. All authors contributed to the study and reviewed and approved the manuscript. Funding: This work was supported by the National Natural Science Foundation (No: 41701536, 61701047, 41674040, 41201468) of China, the Natural Science Foundation of Hunan Province (No. 
 RADAR ANTENNAS 227  by the antenna to the incident wave. The gain G and the effective area !1,. of a lossless antenna  are related by  where ,l = wavelength  A = physical area of antenna . 
 FORM AND SYSTEM DESIGN  WHICH INCLUDES COMPONENTS THAT MAY BE NONLINEAR WITH FREQUENCY  ETC 4HESE SIDELOBES WILL BE STABLE 4HAT IS  THEY SHOULD REPEAT PRECISELY ON A PULSE 
 The range  and doppler frequency shift can also be continuously tracked, if desired, by a servo-control  loop actuated by an error signal generated in the radar receiver. The information available  from a tracking radar may be presented on a cathode-ray-tube (CRT) display for action by an  operator, or may be supplied to an automatic computer which determines the target path and  calculates .its probable future course.  The tracking radar must first find its target before it can track. 
 The error caused by ArcSAR imaging on the reference plane is analyzed in Section 3. The principle of the interferometric DEM-assisted high precision imaging method is given in Section 4. The DEM accuracy and deformation monitoring accuracy of proposed method are analyzed in Section 5. 
 If data is processed DOPPLER (Hz) (a) FIG. 24.27 (a) Amplitude versus doppler is plotted for a sequence of three 12.8-s coherent dwells. Indicated are a target marked T, the approach and recede resonant sea clutter peaks marked A and /?, and the position for taking the noise sample marked N. 
 Gupta and W. D. Burnside, “Physical optics correction for backscattering from curved   surfaces,” IEEE Trans ., vol. 
 January. 1957. 65.Rinehart. 
 December, 1955.  36. Blasbalg, H.: The Relationship of Sequential Filter Theory tp Information Theory and Its Application  to the Detection of Signals in Noise by Bernoulli Trials, IRE Trans., vol. 
  FOR ITH ELEMENT IN  THE JTH GROUP 0P .N N    x . n  0PPN .K 
 Cantalloube, H.; Dubois-Fernandez, P . Airborne X-band SAR imaging with 10 cm resolution: Technical challenge and preliminary results. IET Radar Sonar Navig. 
 For the constant beamwidth assumed, the clutter-to-signal ratio increases  with range and is 47 dB at 1000 nmi. Large clutter-to-signal ratios are typical of HF  radar; some form of doppler filtering is used to separate targets from clutter. In Figures 20.32, 20.33, 20.34, and 20.35, performance estimation curves are given  for winter and summer seasons, night and day, and low solar activity. 
 The outputs froni  the elements must be limited to a bandwidth B before adding them all together, if noise overlap  is to be avoided. The required bandwidth of the summed signal channel is Nl,, which must be  made greater than NB. This can be quite large (perhaps several gigahertz in some radars) and  can represent a limitation on the implementation of the technique. 
 VI ** 28 49.5 ASV Mk. VII * 15 36 Figure 7.1. Detection ranges versus height for ASV Mks III and VI for U-class submarine (from [ 2]).Airborne Maritime Surveillance Radar, Volume 1 7-4. 
 RIAL IS  TO A FIRST ORDER  LINEARLY RELATED IN D"Mn  TO FREQUENCY )T IS NOT SUFFICIENT TO  CONSIDER ONLY THE LOW FREQUENCY CONDUCTIVITY WHEN ATTEMPTING TO DETERMINE THE LOSS  TANGENT OVER THE FREQUENCY RANGE  TO  (Z )N THE CASE OF A MATERIAL THAT IS DRY  AND RELATIVELY LOSSLESS  IT MAY BE REASONABLE TO CONSIDER THAT TAN  CE IS CONSTANT OVER THAT  FREQUENCY RANGE (OWEVER  FOR MATERIALS THAT ARE WET AND LOSSY SUCH AN APPROXIMATION IS INVALID (OWEVER  THERE ARE A NUMBER OF OTHER FACTORS THAT INFLUENCE THE EFFECTIVE PENETRATION DEPTH  NOTABLY THE STRENGTH OF REFLECTION FROM THE TARGET SOUGHT  AND THE DEGREE OF CLUTTER SUPPRESSION OF WHICH THE SYSTEM IS CAPABLE ! FIRST ORDER ESTIMATE OF THE VARIOUS CONTRIBUTIONS TO SIGNAL LOSS CAN BE CARRIED OUT  USING THE STANDARD RADAR RANGE EQUATION  ALTHOUGH THIS IS ONLY APPLICABLE FOR FAR 
 W. Haydon, “Predicting statistical performance indexes for high fre - quency telecommunications systems,” ESSA Tech. Rept. 
 Since the rms noise is dependent on the IF bandwidth, the effective dynamic range decreases with increasing IF bandwidth. The balanced-diode mixer exhibits the largest dynamic range for a given IF bandwidth. However, the dynamic range of the mixer preceded by a low-noise amplifier will be reduced in proportion to the gain of the amplifier. 
 31, pp. 315–332, 1993. 85. 
 TARGET RETURNS 4HE PICTURE ON THE RIGHT SHOWS THE EFFECTIVENESS OF TH E -4) CLUTTER REJECTION  4HE CAMERA SHUTTER WAS LEFT OPEN FOR THREE SCANS OF THE ANTENNA THUS  AIRCRAFT SHOW UP AS A SUCCESSION OF THREE RETURNS -4) RADAR UTILIZES THE DOPPLER SHIFT IMPARTED ON THE REFLECTED SIGNAL BY A MOVING TARGET TO DISTINGUISH MOVING TARGETS FROM FIXED TARGETS )N A PULSE RADAR SYSTEM  THIS DOPPLER SHIFT APPEARS AS A CHANGE OF PHASE OF RECEIVED SIG 
 Moscow, 1963. Translation available from NTIS, AD 645775. June 28, 1966. 
 Diaz and T. Milligan, Antenna Engineering Using Physical Optics: Practical CAD Techniques  and Software , Boston: Artech House, 1996, pp. 193–196. 
 116-126, April 1961. Reprinted in Barton, D. K.: "CW and Doppler Radars," vol. 
 TO 
 rcflcctarray in a manner analogous to a point-feed illuminating a lens or reflector antenna. The  rarallcl pla1e feed uses the principles of microwave structures to provide efficient power  division. It is. 
 Because residual background reflec - tions contaminate the desired target echo  signal, they should be minimized by careful  range design and operation. Interior walls in  indoor test chambers must be covered with  high-quality radar-absorbing material, and  the surface of the ground on outdoor ranges  should be smooth and free of vegetation.  Target support structures should be designed  specifically for low echo characteristics. 
 Morris and L. Harkness, Airborne Pulsed Doppler Radar,  2nd Ed. Norwood, MA: Artech  House, Inc., 1996, p. 
 Thus, although there is often guidance  from either observation or theory, the predictions of such models will be based on  uncertain assumptions about these crucial parameters. As an example, water surface  stability arguments prevent the interior angle of a sharpening wave crest from fall - ing below 120°, which then becomes a convenient measure of the wedge angle in  wedge-scattering models. In Figure 15.21, the overall scale of wedge scattering as  calculated by the GTD was adjusted to locate the cluster of cross sections at the level  of the experimental values. 
 The tuning also affected the pulse Figure 2.4. Aerial installation ARI 5002 for a Sunderland [ 7].Airborne Maritime Surveillance Radar, Volume 1 2-8. repetition frequency, although the pulse length was approximately constant for a given power supply voltage. 
 x°£n  2!$!2 (!.$"//+  -02& 
 NOISE RATIO #.2   AS DETERMINED BY USING &IGURE  4HE TARGET 2#3 IS LABELED hSIZEv AND IS  TREATED AS CONSTANT. Óä°È{  2!$!2 (!.$"//+  &)'52%   2ADAR PERFORMANCE ESTIMATE FOR *ANUARY  54#   33.    &)'52%   2ADAR PERFORMANCE ESTIMATE FOR *ANUARY  54#   33.    .   (& /6%2 
 Validation of the Precision of PolSAR in Estimating TEC Integrating the electron density proﬁle of ISR up to the altitude of PALSAR gave the TEC of ISR along the observing direction. The VTEC of ISR was obtained by using Equation (10), but the ηof ISR is the angle between the beam direction and the vertical direction. Equation (1) tells us that the value of PolSAR TEC is affected by the mid-value /angbracketleftBcosθ/angbracketright[13]. 
 Thefirstexperimental radarsystemsoperated withCWanddepended fordetection upon theinterference produced between thedirectsignalreceived fromthetransmitter andthe doppler-frequency-shifted signalreflected byamovingtarget.Thiseffectisthesameasthe rhythmic flickering, orflutter,observed inanordinary television receiver, especially onweak stations, whenanaircraft passesoverhead. Thistypeofradaroriginally wascalledCW wal}e-inte~rere'lce radar.Today,sucharadariscalledabistaticCWradar.Thefirstexperimen­ taldetections ofaircraftusedthisradarprinciple ratherthanamonostatic (single-site) pulse radarbecauseCWequipment wasreadilyavailable. Successful pulseradarhadtoawaitthe development ofsuitable components, especially high-peak-power tubes,andabetterunder­ standing ofpulsereceivers. 
 1037.-Type Epulse-forming network, f.–1.1to1.2To– Lo=inductance per mesh L=end inductance C=capacity per mesh n=number ofmeshes Zo =surge impedance TO=pulse length 1=coil length ofone meal] d=coil diameter. dielectric constant is5to6and thesafe operating dielectric strength is500 to700 volts perthousandth ofaninch. Greater uniformity would raise thelatter to800volts perthousandth. 
 26. Rarrick. I). 
 17.2. The Elements ofRadar Relay .—One obvious method ofrelaying radar information istotelevise anindicator screen attheradar siteand to transmit the information byexisting television means. This system leads toaloss both insignal-to-noise ratio and inresolution because persistent displays do not televise well. 
 FORCE WINDS OF  KT  IT RISES TO ALMOST  FT  WHICH IS A RATHER FORMIDABLE SEA ,OOKING AT THE SEA  AN OBSERVER MIGHT DESCRIBE WHAT IS SEEN IN TERMS OF A SUBJECTIVE  STATE OF THE SEA  EG  hSMOOTH v hROUGH v OR hTERRIFYINGv )F THESE DESCRIPTIONS ARE LISTED  IN ORDER OF SEVERITY AND ASSIGNED NUMBERS  THESE NUMBERS DEFINE A SEA STATE ! SIMILAR  NUMERICAL SCALE EXISTS FOR WIND SPEEDS  THE  "EAUFORT WIND SCALE   WITH NUMBERS ABOUT  AN INTEGER HIGHER THAN THE CORRESPONDING SEA STATE "UT IT IS SELDOM USED IN REFERENCE  TO SEA CLUTTER 4HERE ARE  THEN  TWO NUMBERS COMMONLY USED TO INDICATE THE ACTIVITY OF THE SEA  SURFACE A SUBJECTIVE SEA STATE AND A MEASURED WIND SPEED /NLY WHEN THE WIND HAS SUFFICIENT  FETCH AND  DURATION TO EXCITE A  FULLY DEVELOPED SEA  CAN A WAVEHEIGHT BE UNAM 
 NOLOGY ALLOW FOR CIRCUIT FUNCTIONS TO BE PROCESSED INTO VERY  VERY SMALL  CONVENIENTLY PACKAGED CHIPS 4HE WIDE BANDGAP SEMICONDUCTORS  SUCH AS 3I# AND 'A.  ARE ALSO COMPATIBLE WITH --)# PROCESSING BUT ARE ALSO CAPABLE OF VERY HIGH POWER OUTPUT LEVELS 4HESE SEMICONDUCTORS HAVE MATERIAL PROPERTIES THAT LEAD TO HIGH BREAKDOWN VOLTAGE WITH COMMENSURATELY HIGH CHANNEL CURRENTSAN ORDER OF MAGNITUDE HIGHER POWER OUTPUT THAN 'A!S 4ABLE   &OR THE UPPER END OF THE SOLID 
 Ó{°ÓÓ  2!$!2 (!.$"//+  4HE 34!0 GENERATES A SPACE 
 SIDELOBE  ADAPTIVE ARRAY ANTENNA v 4HE ,INCOLN ,ABORATORY *OURNAL  VOL   NO   PP n    7 & 'ABRIEL  h!DAPTIVE DIGITAL PROCESSING INVESTIGATION OF $&4 SUB 
 4 AMPLIFIER PAIR WITH A  n OFFSET   4HE AMPLIFIER INPUT VOLTAGE REFLECTION COEFFICIENT IS GIVEN AS  ' AND THE AMPLIFIER VOLTAGE GAIN AS    ! 2EPRINTED WITH PERMISSION FROM % $ /STROFF ET AL   3OLID 
 Significant advances are evident in the digital and SAW techniques.FREQUENCY FREQUENCY TIME (a) SYMMETRICAL (b) NONSYMMETRICALTIME . These two techniques allow the implementation of more exotic signal waveforms such as nonlinear FM. The digital approach has blossomed because of the manyfold increase in the computational speed and also because of the size reduc- tion and the speed increase of the memory units. 
 The ideal limiter is perfectly linear up to the power level at  which limiting begins followed by a transition region beyond which the output power  remains constant. In addition, the insertion phase is constant for all input power lev - els, and recovery from limiting is instantaneous. The output waveform from a band - pass limiter is sinusoidal, whereas the output waveform from a broadband limiter  approaches a square wave. 
 Thelargcattcnuations experienced atmillimeter wavclcngths isoneofthcchiefrcasons long-range, ground-based radarsareseldomfound above35GHz(Kahand). Theattenuation oftheatmospheric gasesdecreases withincreasing altitude. Thusthe attenuation experienced hyaradarwilldcpcndallthealtitudeofthetargetaswellasthe rangc.Withaground-based radartheattcnuation isgreatest whentheantenna pointsto thehori/on, anditislcastwhenitpointstothezenith.Figure12.10givesexamples of thetwo-way attenuation forelevation anglesof0and5°. 
 Iri Fig. 5.1 2 two antennas are shown separated by a distance d. The distance to the target  is H and is assumed large corllpared with the antenna separation d. 
 The time separation between the echoes rece~ved in  the vertical arid slant beams is a measure of the target height. A short time-separation signifies  low altitude, while longer separations occur with high altitude targets. Two separate retlectors  may be used to generate the two fan beams,=' the two reflectors might be back to back, a single  reflector with two feeds cana be ~sed,J!!~~ or the two beams can be generated with a single  phased array antenna.$ The. 
 It might have an average power as small as milliwatts or as large as mega - watts. (The average power is a far better indication of the capability of a radar’s perfor - mance than is its peak power.) Most radars use a short pulse waveform so that a single  antenna can be used on a time-shared basis for both transmitting and receiving. The function of the duplexer  is to allow a single antenna to be used by protecting  the sensitive receiver from burning out while the transmitter is on and by directing the  received echo signal to the receiver rather than to the transmitter . 
 The lower dashed curve is for minimum galactic noise, zero sun noise, 90° elevation angle. (The bump in the curves at about 500 MHz is due to the sun-noise characteristic. The curves for low elevation angles lie below those for high angles at frequencies below 400 MHz because of reduction of galactic noise by atmospheric absorption. 
 TO 
 ASV for the detection of surfaced vessels from the air gave at least a partial answer and had a signi ﬁcant impact on the conduct of naval warfare from that time [ 1]. This book describes the ASV radars developed in the UK and used by RAF Coastal Command during WWII for long-range maritime surveillance. 1.2 RAF Coastal Command RAF Coastal Command was the user of all the radars described in this book. 
 The corresponding doppler and doppler rates are  also given in Figure 5.29. For a ship whose principal scatterers are less than 85 ft above the center of gravity,  the dopplers will be in the range of ± 50 Hz at X band with a rate of change of up to   ± 31 Hz/s. As long as the image resolution is not too great, each range-doppler bin can  be match filtered using the hypothesized motion for each scatterer and an image can  be formed on the ship. 
 27. R. A. 
 Cruz-Pol, and J. Colom, “Distributed Collaborative Adaptive Sensing (DCAS) for improved  detection, understanding and prediction of atmospheric hazards,” presented at 85th AMS Annual  Meeting , San Diego, AMS, 2005. 154. 
 •Create Feature Space: –Generate hxhblocks for each pixel in Xdi fwhere the pixel is in the center of the block. –Use OMP algorithm to generate the projections of the data onto the dictionary. •Clustering: Use the k-means algorithm to classify the feature space into two classes, e.g. 
 Figure 9shows the optical images of the three targets. Figure 10shows the RCS curves of the three pixels. Pixel A from the lawn is shown as isotropic scattering. 
 A long­ persistence screen such as the P19 is appropriate for PPI presentations where the frame times  are on the order of several seconds. On the other hand, where no persistence is needed, as when  the frame time is less than the response time of the eye (0.1 s or less), a PI phosphor might he  used. The Pl phosphor is commonly found in most A-scope presentations. 
 CF AR, however, is not without its disadvantages and can be  considered a necessary evil. It introduces an additional loss compared to optimum detection,  and in some systems the number of pulses processed needs to be large to keep the loss low.  More important, CF AR maintains the false-alarm rate constant at the expense of the probabil­ ity of detection. 
 The color is controlled by the anode voltage which  determines the depth of penetration of the electron beam into a series of phosphor layers.  Varying the anode voltage varies the depth of penetration and the particular phosphor layer  that is excited. Typically, the difference between penetration of the layers is about 4 kV per  layer.:rn A single-electron-gun. 
 2.54  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 (this dictates the location of the peak), that the response to chaff at 0.8 doppler be  down 46 dB, and that the mismatch loss be minimized. Minimizing the mismatch loss  is accomplished by permitting the filter sidelobes between 0.3 and 0.8 to rise as high  as needed (lower sidelobes in this range increase the mismatch loss). The second zero- doppler filter is the mirror image of this one. 
 WAVE &- 
            
 1957. 21.Bean.B.R.G.D.Thayer.andR.A.Cahoon: Methods orPredicting theAtmospheric Bending of RadioRays.Natl.Bur.Stalldards (U.S.)J.Research. vol.64D,pp.487-492, September/October. 
 Withaircrafttargetsaneffective pulsewidthofseveralnanoseconds (kssthanameterrange­ resolution) canresolvetheindividual scatterers. Oncethescatlcrers an:n:solved inrange,an anglemeasurement canbeobtained oneachonebyuseofmonopulse. Thisprovides a three-dimensional" image"ofthetargetsincetheazimuth andelevation ofeachscallerer is givenalongwiththerange.Figure5.20isanexample ofthetypeofradarimagethatmightbe obtained withanaircraft. 
 Croney. J. · Clutter on Radar Displays, Wireless Engr., vol. 
 Figure 10.6c shows the charges and electric fields another quarter period later. Figure 10.7 isaview ofthemagnetron opened outinaplane parallel tothe cathode sothat the anode faces lieonaplane. The broken lines show the paths ofmagnetic flux attheinstant shown inFig. 
 Azcueta, M.; Tebaldini, S. Non-Cooperative Bistatic SAR Clock Drift Compensation for Tomographic Acquisitions. Remote Sens. 
   6OL  .ORWOOD  -! !RTECH (OUSE  )NC     PP n  , (ELGOSTAM AND "  2ONNERSTAM  h'ROUND CLUTTER CALCULATION  FOR AIRBORNE DOPPLER RADAR v  )%%%  4RANSACTIONS ON -ILITARY %LECTRONICS  VOL -), 
 Apulseformed onthose cycles inwhich radaris )+–,I Il——————— —————— —______ __ 1 I I i)CompassJuI 4oo-Scaleof2I multoPulse oscillatorI vibratorformerI Ir1f ~ Switch 1 Filter 1_Beacon I 1-Phaae sensitive +rectifier L___–____WhWKi l-- .————————— —————I1 I , Trigger I 1I(everycyck) I 30PsecI delayI LJI Ii 1i I 1CosineModulator pulse I Trigger* IpulseII(radarcycke) I VideoIRadarvideo ReceiverCircuitof— Fig.17.14Switch I 4IBeaconvideo I IAngledata9 L____An!yz~ ?Qd:c~ !E!n!!~r _–_~ FIG.17.22.—Am-to-surface relaysystem. transmitted ispassed tothe coder toserve asanidentifying pulse inthe relay channel. When the beacon signals are not desired, the relay of Fig. 
 96. Tischer, F. J.: H Guide and laminated Dielectric Slab. 
 Target Size For a speciﬁc beam width, bearing measurements of small targets are more accurate than large targets because the centers of the smaller pips ofthe small targets can be identiﬁed more accurately. Target Rate of Movement The bearings of stationary or slowly moving targets can be measured more accurately than the bearings of faster moving targets. Stabilization of Display Stabilized PPI displays provide higher bearing accuracies than unstabilized displays because they are not affected by yawing of the ship. 
 19.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 fields in precipitation. This pioneering work led the way toward the use of networks  of doppler radars for studies of individual clouds to examine the three-dimensional  structure of vector air motion in precipitation. A point should be made here regarding  the use of two doppler radars for measurements of three-dimensional winds. 
 DIVERSE RADARS !S NOTED  THERE EXIST SEVERAL POLARIMETRIC RESEARCH RADARS AND OPERATIONAL RADARS IN THE WORLD  -ULTIPLE 2ADARS  ! SINGLE DOPPLER RADAR MEASURES ONLY A SINGLE RADIAL COMPO 
 195, pt.1, York (UK), April 13–16, 1981,   pp. 185–189. 57. 
 The 2 μs pulse length was mainly used for beacon interrogation. Th e antenna had an azimuth beamwidth of about 3 °.Airborne Maritime Surveillance Radar, Volume 1 8-2. 8.1.1.3 ASV Mk. 
 Day and Fred M. Staudaher3.1 3.1  Systems Using Airborne MTI Techniques / 3.1 3.2  Coverage Considerations / 3.2 3.3  Airborne MTI Performance Drivers / 3.3 3.4  Platform Motion and Altitude Effects on MTI Performance / 3.3 3.5  Platform-motion Compensation Abeam / 3.10 3.6  Scanning-motion Compensation / 3.14 3.7  Simultaneous Platform Motion and Scan Compensation / 3.18 3.8  Platform-motion Compensation, Forward Direction / 3.21 3.9  Space-time Adaptive Motion Compensation / 3.23 3.10  Effect of Multiple Spectra / 3.31 3.11  Example AMTI Radar System / 3.32 Chapter 4 Pulse Doppler Radar John P. Stralka and William G. 
 TIPLE FREQUENCIES AND WITH SCANNING 0HASED ARRAYS ARE VERY EXPENSIVE !S TECHNOLOGY ADVANCES  COSTS ARE EXPECTED TO BE  REDUCED !T THE SAME TIME  THE QUEST FOR BETTER PERFORMANCE WITH LOWER SIDELOBES AND WIDER BANDWIDTH KEEPS THE COSTS HIGH 0HASED !RRAY !NTENNAS  4HE PHASED ARRAY ANTENNA HAS AN APERTURE THAT IS ASSEM 
 10t040 Mountains ..........................25 t030 5000-ton ship........ ......25 Ground beacons .............. 150(ifnotlimited byhorizon) Portable ground beacons (low power). 
 FIT LINEAR PHASE AND HAS SIMILAR EFFECTS AS AMPLITUDE RIPPLE 'ROUP DELAY  THE RATE OF CHANGE OF PHASE VS FREQUENCY  IS IDEALLY CONSTANT FOR LINEAR PHASE FILTERS 4HE ABSOLUTE VALUE OF GROUP DELAY DOES NOT IMPACT THE RANGE SIDELOBE PERFOR 
 Radar echoes from land, sea, rain, birds, and other such objects are not always undesired.  Reflections from storm clouds, for example, can be a bother to a radar that must see aircraft.  but storm clouds are what the radar meteorologist wants to see in order to measure rainfall  rate over a large area. 
 Theshapeofaradome foraground-based antenna isusuallyaportionofasphere.The sphereisagoodmcchanical structure andoffersaerodynamic advantage inhighwinds. Prccipitation particles blowaroundasphereratherthanimpinge uponit.Hencesnowor othcrfrolcnprccipitation isnotreadilydcposited. Thcfirstlargeradomes (50-ftdiameter ormore)forground-based radarantennas ap­ peenedshortlyafterWorldWarII.Theywereconstructed ofastrong,flexiblerubberized airtight matcrial andweresupported byairpressure fromwithin.t03Sincethematerial of air-supported radomes canberelatively thinanduniform, theyapproximate theelectrically idealthinshellwhichprovides goodelectrical properties. 
 -  average radiation intensity  where the radiation intensity is the power per unit solid angle radiated in the direction (0, 4)  and is denoted P(8, 4). A plot of the radiation as a function of the angular coordinates is called  a radiation-intensity pattern. The power density, or power per unit area, plotted as'fi function of  angle is called a power pattern. 
 19.8. In the conventional receiver, the target signal must compete with feedthrough, clut- ter, and jamming until the final stages, with the dynamic-range requirements of the receiver and its AGC loops dictated by these large undesired signals. The in- verse receiver, on the other hand, excludes them virtually at the input. 
 TARGET PLUS TARGET 
 ORDER  WAVEGUIDE MODES TO EXTRACT ANGLE 
 A block diagram of a CW tracking illuminator  is shown in Fig. 3.9.)' Note that following the wide-band doppler amplifier is a speed gate,  wl~icli is a narrow-band tracking filter that acquires the target's doppler and tracks its chang  ing doppler freq~~ency shift.  3.3 FREQUENCY-hlOL)ULAI1ED CW RADAR  The inability of the simple CW radar to measure range is related to the relatively narrow  spectrum (bandwidth) of its transmitted waveform. 
 END  AS SHOWN IN &IGURE  C  PRODUCING COPIES OF THE  TO  " PORTION OF THE  SAMPLED SIGNAL SPECTRUM AT " INTERVALS &IGURE  SHOWS THE RESULT OF SAMPLING BELOW THE .YQUIST RATE &IGURE  A  SHOWS THE SAME BANDLIMITED SIGNAL AS THE PREVIOUS EXAMPLE  BUT THIS TIME IT IS SAMPLED AT SOME RATE THAT IS LESS THAN .YQUIST RATE  " 4HE RESULTING SAMPLED SPECTRUM  SHOWN IN  &IGURE B AND  C  CONTAINS OVERLAPPED  OR ALIASED  SPECTRAL COMPONENTS THAT ADD AND  REPRESENT CORRUPTION OF THE SIGNAL &IGURE  REPEATS THIS .YQUIST ANALYSIS FOR A  BANDPASS SIGNALA SIGNAL NOT  CONTAINING SPECTRAL COMPONENTS AT OR NEAR  (Z &IGURE  A SHOWS A REAL BANDPASS  SIGNAL WITH TWO 
 ARRAY MODEL HAS PREDICTED WITH GOOD ACCURACY THE ARRAY IMPEDANCE AND THE IMPEDANCE VARIATIONS %VEN ARRAYS OF MOD 
 VA, B 285.5 55Mk. VI 99.2 13.2Mk. VIA 159.8 19.4Mk. 
 The deviation requirements in Table 17.5 were derived for the worst case, where the two common modulating signals are 180° out of phase or one edge of the received clutter pulse is completely eclipsed in the independent case. Frequency Modulation. Common FM permits relaxed modulation require- ments at low frequencies but 6 dB more severe requirements at high frequencies compared with independent FM.44 This effect is caused by the range delay of the clutter. 
 Miller, Introduction to Adaptive Arrays , New York: John Wiley & Sons,  1980, pp. 78–279. 27. 
 DISCERNABLE 
 EDGE RANGE TRACKER 4HE ASSUMPTION IS THAT THE DECEPTION JAMMER NEEDS TIME TO REACT AND THAT THE LEADING EDGE OF THE RETURN PULSE WILL NOT BE COVERED BY THE JAMMER 02) JITTER AND FREQUENCY AGILITY BOTH HELP TO ENSURE THAT THE JAMMER WILL NOT BE ABLE TO ANTICIPATE THE RADAR PULSE AND LEAD THE ACTUAL SKIN INTERVAL !LTERNATIVELY  THE TRACKING RADAR MIGHT EMPLOY A MULTIGATE RANGE 
 “Technical parameters for radar beacons (racons),” ITU Recommendation M.824-2, International  Telecommunication Union, Geneva. 32. A. 
 / Ê* 
 2.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 The values of rms spectral spread of land clutter as derived from the data in  Billingsley9 agree quite well with previous studies. It can probably safely be stated  that the polynomial model of land clutter spectra is far too pessimistic at spectral  values below –40 dB and should be avoided for radar analysis requiring a large clutter  attenuation value. The case for the exponential model, as presented by Billingsley, is quite convinc - ing, and this model has been widely accepted as being the most accurate for radar  performance predictions. 
 £      &IGURE  SHOWS A COMPARISON OF THE COMPRESSED PULSE RESPONSE FOR THREE FRE 
 IZE MARINE RADAR CLUTTER PERFORMANCE TESTS  INCLUDING SOME RESEARCH PERFORMED ON BEHALF OF THE 5+ -ARITIME AND #OASTGUARD !GENCY   4HIS APPROACH WAS AIMED TO MINIMIZE  ANY SPECIAL CONFIGURATION OF THE RADAR UNDER TEST )T IS BASED ON A SYSTEM THAT GENERATES SIMULATED TARGET AND CLUTTER WAVEFORMS 4HESE ARE PICKED UP BY THE ANTENNA OF THE RADAR UNDER TEST FROM A NEARBY TRANSMITTING SOURCE  TYPICALLY SITUATED ABOUT  METERS FROM THE RADAR ANTENNA #O 
 In some array designs with  frequency-dependent phase shifters, tlie frequency also must be supplied to the beam-steering  cotiiputer along with the two angles.  In sonie cases the generation arid distribution of a large number of individual phase-  shifter commands (one for each element) might be economically prohibitive. In devising  computation algorithms and computer hardware, advantage can be taken of the fact that the  phase shift $,, required at the rr~r~th element of a rectangular-spaced array can be separated by  row atid coli~t~in since JI,, = r,r$, + , where r~t. 
 For example, the AN/APQ-13, abombing radar whose manufacture was just beginning atthe end ofthat year, has aninstalled weight of 620 lbwithout itsspecial bombing facilities, and requires 100 amp of 28-volt aircraft power. Ithas 24controls tobeadjusted, omitting those concerned with itsbombing function. Forty-two cables arerequired to interconnect its19separate component boxes. 
 When properly illuminated by a point source at the focus, the  paraboloid generates a nearly symmetrical pencil-beam antenna pattern. Its chief application  has been for tracking-radar antennas.  An asymmetrical beam shape can be obtained by using only a part of the paraboloid. 
 TARGET INDICATION -4)  CLUTTER RESIDUES /NE CAN LIMIT THE NUMBER OF FALSE ALARMS WITH A FIXED 
 35-38, 60,  [kcember. 1976.  92. 
 TheIdealObserver appliesequalweighttoanerrorduetoafalsealarmandtoanerror duetoamiss.However, theremaybecasesinwhichequalweightisnotappropriate (Bayes criterion).Iftheerrorsarenotofequalimportance, thetheoryoftheIdealObserver maybe modified totakethisintoaccount usingtheconcepts ofstatistical decision theory.24.32-H Unfortunately, inmostradarapplications thereisnorealistic basisforassigning avaluetoa missortoafalsealarm;consequently, theusefulness ofdecision theoryinradarislimited. Sequential observer. Mostradarsutilizetheequivalent oftheNeyman-Pearson Observer and operatewithafixednumber ofpulses.However, thedetection decision mightverywellbe madeonthebasisofonlyafewobservations orpossibly asingleobservation, anditwouldnot benecessary torecordthelaterobservations thatoccuroncethethreshold hasbeencrossed. 
 For the case on hand a high -pass filter, as a waveguide, would be suitable.  If the higher fr e- quencies are to be delayed, opposite of the example in Figure 8.19, then low -pass filters can be  . Radar System Engineeri ng Chapter 8 – Pulse Radar  65     used. 
 S. P. Applebaum, “Adaptive arrays,” Syracuse University Research Corporation Rept. 
 or,  or.  Radius a  l r r  (al d (statute miles) = J21i(ft)  d (nautical miles)= 1.23 jh(ft}  d (km)= 130 Jli(km)  Radius ka  l  J (bl (12.llh)  (12.llc)  (12.lld)  Figure 12.6 (a) Bending of antenna beam due to refraction by the earth's atmosphere; (h) shape of beam in  equivalent-earth representation with radius ka. 450 INTRODUCTION TO RADAR SYSTEMS  Equations (12.11) have been used at times as a measure of the line-of-sight coverage of a  ground-based radar viewing a target at a height h. 
 Discontinuities, called severs, are necessary in the slow-wave structure of high-power TWTs to prevent oscillation due to reflections at input and output of the structure. Although oscillation could also be prevented by distributing loss along the structure, this would result in lower efficiency, which is unattractive in high-power tubes. Typically, a sever is used for each 15 to 30 dB of tube gain. 
 -t.  Boxcar  generator Range  gate  No. 2 --t. 
 . VI. ‘IMPOSSIBLE’ CIRCUITS  MAN WHO HAD SPENT SOME FIFTEEN YEARS IN THE  construction and servicing of radio receivers was  shown the circuit diagram of a 10-centimetre radar  receiver used in a fairly popular civil-aviation beacon  system. 
 +β ·αMAXSUT TV∑s t r o a g e . :L∑   Figure 12.1  Principle of the CAGO -CFAR circuit.     The CAGO- CFAR (C ell Averaging Greatest Of-) comprises essentially a shift reg ister consis t- ing of two sub- registers, each containing L storage cells. 
 Soc. , vol. 63, pp. 
 142. M. C. 
 DIGITAL CONVERSION INVOLVES TWO STAGES  SAMPLING AND QUANTIZATIONEACH WITH POTENTIAL FOR DISTORTING THE RECEIVED SIGNAL 4HE RECEIVED SIGNALS MUST BE SAMPLED WITH SUFFICIENT PRECISION AND UNIFORMITY TO PRESERVE THE INHERENT SPECTRAL CONTENT ACROSS THE DYNAMIC RANGE  SPANNED BY THE SIG 
 Experimentation with millimeter wavelength radiation and  microwave radiation both date back to the end of the nineteenth century. The first microwave  experiments were those of Hertz in 1886. Experiments at 6-mm wavelength occurred in 1895. 
 28. Sliradcr. W. 
 Moreover, the signal from surfaces without projections falls off very rapidly  for depression angles within a few degrees of grazing. This means that the effect  of small local slopes can be very significant in modulating the return signal, not  just in shadowing. 16.3 THEORETICAL MODELS   AND THEIR LIMITATIONS Descriptions of a Surface. 
 Since 50 J of energy can usually  cause damage to an RF tube (or the switching device) and since the capacitor bank  for an active-switch modulator must often store far more than 50 J (to prevent exces - sive droop), some means must be provided to divert the stored energy when an arc  discharge occurs. Such a device is the crowbar,  so called because it is equivalent to  placing a heavy conductor (like a crowbar) directly across the power supply to divert  the energy and thus prevent the energy from discharging through the tube and caus - ing serious damage. A crowbar is, therefore, needed for a high-power active-switch  modulator because of the large amount of energy stored in its capacitor bank. 
 TIONS IN THE FOLLOWING STAGES  AS NOTED ABOVE  ALL OF WHICH MUST BE COUNTED L 4IME JITTER IN CASCADED STAGES SIMPLY ADDS UNLESS THE STAGES ARE ARRANGED TO CANCEL OR  TO BE ROOT 
 TIVE TO SUMMARIZE THE PRINCIPLE DIFFERENCES BETWEEN SKYWAVE RADAR AND CONVENTIONAL MICROWAVE RADAR 4HIS PROVIDES A CAUTIONARY REMINDER NOT TO EXTRAPOLATE TOO READILY FROM THE FAMILIAR CHARACTERISTICS OF THE MICROWAVE DOMAIN TO THE (& BAND (& SKYWAVE RADARS OPERATE AT RANGES ABOUT AN ORDER OF MAGNITUDE GREATER THAN  MICROWAVE LONG 
  PRESERVES NO CORRELATIONS  HOWEVER STRONG THEY MAY BE 3EVERAL FORMS OF DATA ANALYSIS AND DISPLAY ARE ACCESSIBLE  BUT PERHAPS THE MOST USE 
 Because  of the circular symmetry of the reflector surface in the horizontal plane, th~ beam can bc  readily scanned in the plane without any deterioration in the pattern.  The wave reflected from the surface of the parabolic torus is not perfectly plane, but it can  be made to approach a plane wave by proper choice of the ratio of focal length f to the radius  of the torus R. The optimum ratio offlR lies between 0.43 and 0.45.39  Good radiation patterns are possible in the principal planes with sidelobes only sl~ghtly  worse than those of a conventional paraboloid. 
 Winchell and D. Davis, “Near field blockage of an ultralow sidelobe antenna,” IEEE Trans .,  vol. AP-28, pp. 
 ‘(Throughout thewhole ofthedevelopment period thesmall team who were responsible ruthlessly sacrificed allrefinements, elegancies and versatilities in thedesperate need forsomething tobegoing onwith. They never turned aside from their cult ofthethird best—(’ The best never comes, thesecond best comes toolate. ”1 Atthe frequency used, strong reflections from the ionosphere occur, and anextremely low repetition rate of25pps was used inorder toensure that ionospheric echoes were not confused with echoes from aircraft targets. 
 CODED WAVEFORM IS CONSTANT  IN MAGNITUDE WITH TWO PHASE VALUES   n OR n 4HE BINARY CODE CONSISTS OF A  SEQUENCE OF EITHER S AND S OR   S AND  
 Thistypeofconstruction isalsosuitable for mechanically rotating antennas. Figure8.17(ANjSPS-48) showsastackofslottedwaveguides forforming abeamthatisfrequency-scanned inelevation. Theslottedguidesforming therows oftheantenna aresometimes calledsticks.Thepowercoupled outoftheguidebytheslotisa function oftheangleatwhichtheslotiscut.Whenhalf-wavelength-spaced slotsarefedina seriesfashion, thefieldinsidetheguidechanges phaseby1800between elements. 
 ..............................  12  Free-space Path Loss  ................................ ................................ 
 Their work was disclosed in a patent issued in 1934. 59  The early experiments with wave-interference (bistatic) radar led to the development of mono­ static radar in the late 1930s in both this country and abroad. Further development was put  aside after the demonstration of the more versatile monostatic-radar principle. 
 The velocity of  propagation of electromagnetic energy is slowed down by the periodic structure so that it is  nearly equal to the velocity of the electron beam. It is for this reason that helix and sim~lar  microwave circuits are called slow-wave structures or delay lines. The synchronism between  the electromagnetic wave propagating along the slow-wave structure and the d-c electron  beam results in a cumulative interaction which transfers energy from the d-c electron beam to  the RF wave, causing the RF wave to be amplified. 
 High-resolution microwave images of the observed scene can be obtained under various environmental conditions. Thus, UAV-SAR attracts growing interest in recent years [ 14]. The possibility of developing commercial low-cost systems is anyway still limited by the complication of the development of SAR due to the precise need for mission parameters to obtaingood-quality images. 
 SURFACE HEIGHT  THE SATELLITE RADAR ALTIMETERS WAVEFORM SUPPORTS  TWO OTHER OCEANOGRAPHIC MEASUREMENTS SIGNIFICANT WAVE HEIGHT 37(  AND SURFACE WIND SPEED 73  /VER A QUASI 
 After adjusting C11 to cancel the sum of the other mutuals, they further ad- justed the amplitude of C1, to compensate for the variation in mismatch loss due to the resultant change in C11. Results were obtained for an array of greater than two-octave bandwidth. In this design grating lobes were permitted to enter real space. 
 DEPENDENT ACCURACY  IS NOT USED 4HE MULTISTATIC RADAR MUST  HOWEVER  USE MULTIPLE  PROPERLY LOCATED SITES WITH BOTH OVERLAP 
 Long-range  dwells are detnatiding of radar execution time, but since they generally involve a low data rate  they are not particularly demanding of data processing time. On the other hand, high data rate  tracking of short-range targets is not as dernandi~ig of radar execution time as for long-range  targets. but the data-processing capability becomes the lin~jting factor. 
 CESSING IS GENERALLY DESIGNED TO EMPHASIZE PRECIPITATION AND WIND 
 This is called aperture blocking or shadowing. The chief example is  RADAR ANTENNAS 233 Another property oftheradiation pattcrns illustrated byTable7.1isthattheantennas withthelowestsidelobes(adjaccnt tothemainbeam)arethosewithaperture distributions in whichtheamplitude taperstoasmallvalueattheedges.Thegreatertheamplitude taper,the lowerthesidclobe levelhutthelesstherelativegainandthebroaderthebeamwidth, Thuslow sidelobes andgoodaperture efficiency runcountertooneanother. Awordofcautionshouldbegivenconcerning theabilitytoachieveinpractice low sidclohe levelswithcxtrcmcly tapercdilluminations. 
 LOGRESIDUE    )F THE RADAR UTILIZES MORE THAN ONE DOPPLER FILTER  THE EFFECT OF 34!,/ INSTABILITY  SHOULD BE CALCULATED FOR EACH INDIVIDUALLY 0ULSE $OPPLER 0ROCESSING   )N PULSE DOPPLER SYSTEMS  A SERIES OF PULSES ARE TRANS 
   +     +    
 WAY GAIN OF  
 ALTITUDE %2 
 74. Davies, D. E. 
 REFERENCES:    1. Introduction to Radar Systems – Merrill I. Skolnik, 3rd Edition Tata McGraw -Hill, 2001. 
 The temperature ofthe airaround ther-fhead may getashigh as50”C indesert areas inside a housing exposed tothesun’s rays. Iftheunit isnotpressurized theper- mitted dMerential of35°C iseasily met. The airfrom asimple blower, properly channeled, will readily carry theheat released inside theenclos- ure out into the surrounding air. 
 RANGE LIMIT OF THE RECEIVER 3UITABLE CLUTTER SOURCES ARE DIF 
 POWER  COMBINERS INCLUDE COAXIAL TRANSMISSION LINES  MICROSTRIP OR STRIPLINE TRANSMISSION LINES  OR WAVEGUIDE 4HE CHOICE OF TRANSMISSION MEDIUM IS GENERALLY A FUNCTION OF MANY PARAMETERS  INCLUDING PEAK AND AVERAGE POWER 
 Diodes are used to switch between the two  stales of susceptance. The spacing between diodes is approximately one-quarter wavelength al  the operating frequency. Adjacent quarter-wavelength-spaced loading-susceptances are equal  and take either of two values. 
 CHAPTER  SEVEN  RADAR ANTENNAS  7.1 ANTENNA PARAMETERS1,*  The purpose of the radar antenna is to act as a transducer between free-space propagation and  guided-wave (transmission-line) propagation. The function of the antenna during transmission  is to concentrate the radiated energy into a shaped beam which points in the desired direction  in space. On reception the antenna collects the energy contained in the echo signal and delivers  it to the receiver. 
 Dahlsjo, 0.: A Low Side Lobe Cassegrain Anti.:nna," Radar- Present and Future," Oct. 23 25, 1973,  IEE Cm!{ P11bl. 110. 
 TION COVER THAN IT IS WITHOUT  HOWEVER !LTHOUGH  MF IS APPARENTLY AT LEAST AS GOOD AS THE  VOLUMETRIC MOISTURE CONTENT FOR RELATING TO R    ITS USE HAS BEEN QUESTIONED 3OIL MOISTURE CAN AFFECT A RADAR IMAGE  AS HAS BEEN DEMONSTRATED IN IMAGERY  OBTAINED FROM THE 3EASAT , 
 This is an economical approach to air-surveillance radars at the  lower radar frequencies, such as VHF. It is also employed at higher frequencies when a  precise aperture illumination is required, as to obtain extremely low sidelobes. At the  lower frequencies, the array might be a collection of dipoles or Yagis, and at the higher  frequencies the array might consist of slotted waveguides. 
 21. Rott, N. On the viscous core of a line vortex. 
 1448–1453, October 1988. 23. O. 
 10.5] MAGNETRON CHARACTERISTICS 351 promise between efficiency and frequency stability and this compromise isarrived atfrom astudy oftheRieke diagram. Itispossible insome cases tocombine with the magnetron proper a high-Q cavity coupled toitinsuch away astoreduce thepulling figure byalarge amount with little ornoloss inefficiency. The ratio ofthe pulling figures with and without thehigh-Q cavity forequivalent operat- ingconditions iscalled the“stabilization factor, ”which may beaslarge as10but isusually between 2and 5. 
 Diurnal variations are relatively small but finite. They  result both from plant moisture changes and from morphological changes (a corn  plant actually lifts its leaves “to meet the sun”; morning glories close their flowers  at night). Most crops are planted in rows. 
 Phased Array Radar Antennas   .............................. 7.1  7.1 Introducti on  .............................................................  7.1  Phased Array Radars  ........................................ 
 §  Space-based SARs tend to look toward the surface at angles that are much closer to vertical than do airborne SARs.  The most commonly used terminology is incidence (the angle at the illuminated surface between the local vertical  and the incoming illumination). The angle of incidence is the complement of the grazing angle, the customary  nomenclature for airborne radars. 
 VARYING ELECTRIC AND MAGNETIC FIELDS THAT LINK THE IONOSPHERIC PLASMA TO THE %ARTH AND TO THE INTERPLANETARY MEDIUM !S A CONSEQUENCE  THE STRUCTURE OF THE IONOSPHERE UNDERGOES CHANGES ON A WIDE VARIETY OF SPATIAL AND TEMPORAL SCALES  WHICH DRASTICALLY AFFECT ITS PROPERTIES AS A MEDIUM FOR RADIOWAVE PROPAGATION 4HE PRIMARY REQUIREMENT FOR RADAR SYSTEM DESIGN IS A QUANTITATIVE DESCRIPTION OF  THE PROPAGATION CHARACTERISTICS OVER THE PROPOSED COVERAGE REGION 3PECIFICALLY  THE RADAR DESIGNER NEEDS A STATISTICAL DESCRIPTION THAT WILL ENABLE MATCHING THE TRANSMITTED SIGNAL  POWER LEVEL  AND ANTENNA GAIN PATTERN TO THE SUPPORTED FREQUENCY SPAN  NOISE LEVELS  PROPAGATION LOSS CHARACTERISTICS  AND  RAY PATHS TO THE TARGET REGION )N ADDITION   THE RADAR OPERATOR NEEDS A MODEL WITH ENOUGH SOPHISTICATION TO PERMIT FULL INTERPRETA 
 Another shelter houses anumber ofB-scopes llsed for reporting signals totheoperations shelter, where they areplotted. The coverage ofeach B-scope canbechosen togive thebest total coverage of the area important tothe operations being carried onbythe station. Another shelter houses thetelephone switchboards, atriangulation table. 
 The power amplifier module consists of 10 identical silicon bipolar power transis- tors arranged in a 2-driving-8 amplifier configuration to develop more than 2500-W peak power output over the 400- to 450-MHz frequency bandwidth. A photograph of the transmitter module is shown in Fig. 5.15. 
 However, since thecorrect beat frequency isproduced. I1M-h,AGC voltage (1) l~o+180v T +120V 470 470 470 470 1 15ooppfI O27fJ-Z25V...IAGC voltage (2)t180~ 1 1 I 120V e“33k . 11From output ofstage 12 3.3k lo,l$uf +005b-1270k$2kk2k+ ~ -22’v FIG.12.22.—1-1andvideo amplifier for very wideband receiver.Eight more ifamplifier stages (5to12) ,dent,cal with 4th stage except for gain control stages (5,7,10 )whlch are ldenttcal to3rd stage. 
 The module phase shifter operates at low-signal power levels. Its insertion loss may  be high because it is followed by amplification on transmit and preceded by ampli - fication on receive. Diode phase shifters are, therefore, quite permissible even with  many bits (e.g., 5, 6, or 7 bits for low sidelobes). 
 ................................ ...........  4  PULSE POWER  ................................ 
 73 39 Actual Gomplex Targets. 75 3.10 Compound Targets Extended through Space 81 311 Extended Surface Targets 85 GFtOWND PAINTING BYAIRBORNE RADAR 88 3.12 Specular and Diffuse Reflection 89 3.13 Sea Return and Ground Return. 92 3.14 Mountain Relief. 
 For low-power  radar applications at millimeter waves, the EIK can be used. Solid-State Amplifiers for Radar Transmitters.  Solid-state transmitters and  vacuum tube transmitters have significant differences, yet they are both employed   ch10.indd   26 12/17/07   2:19:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 518–523. 105. D. 
 A circulator is used on the output port to protect the 100-W devices from antenna-generated reflections, and control cir- cuitry has been included to switch off modules in the event of cooling-system fail- ure. A 14:1 high-power replicated combiner,21 built by using a combination of re- active and resistive power-combining techniques in air dielectric stripline, is employed to sum the module outputs to the 25-kW level. FILTERMATCHFILTER MATCHFILTERFWO REVTO BITE PRODUCTIONTOLERANCEBITEMONITORSBRANCH-LINECOMBINERFINALS BRANCH-LINE3-<JB DIVIDERDRIVER RF SWITCH 3-dB COMBINER/FILTER(WILKINSON)3-dBWILKINSONBITEMONITORRFINPUTLOGIC(BITE) PINSW FIG. 
 ABLE SURFACE ORIENTATIONS FOR ONE THREAT DIRECTION IS CANCELED BY AN ACCOMPANYING ENHANCEMENT IN ANOTHER )N MANY SITUATIONS  HOWEVER  THE GENERAL DIRECTION OF THE THREAT CAN BE FORECAST &IGURE  ILLUSTRATES THE 2#3 REDUCTION AVAILABLE THROUGH SHAPING 4HE PLOTTED  CURVES ARE BASED ON THEORY AND MEASUREMENTS AND SHOW HOW THE NOSE 
 Earth Obs. G éoinf. 2019 ,74, 57–64. 
 76 INTRODUCTION TO RADAR SYSTEMS  .c £ ti D -+j ~-lll ~ 118 ~ ~  D D  C C  0 0  D D  0 0  N N  I I  ' ' >- >-e' e' QJ QJ C C w w  lo lo  Frequency Frequency  (a) (b)  Figure 3.5 Frequency spectrum of CW oscillation of (u) infinite duration and (b) finite duration.  broaden the bandwidth still further. Some of these spectrum-broadening effects are considaed  below. 
 55. Jones, D. M. 
 ch24.indd   65 12/19/07   6:01:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 It can be thought of as a" statistical omnidirec­ tional" pattern. It causes the far-out sidelobes'to differ in the presen~ of error as compared to  the no-error pattern. (The no-error pattern sidelobes generally drop off rapidly with increasing . 
 ForFIG. 4.8 Extended-interaction out- put circuit. (From Ref. 
 POLARIZED BISTATIC CLUTTER  MEASUREMENTS v %LECTRONICS ,ETTERS 
 Figure 5.18 Examples of acquisition  search patterns. (a) Trace of helical  scanning beam; (b) Palmer scan; (c)  spiral scan; (ri) raster, or TV, scan;  (e) nodding scan. The raster scan is  sometimes called an n-bar scan, where  n is the number of horizontal rows. 
 A forest is inherently rougher than either a field or a city. It is harder to see the  difference between the roughness of natural areas and the roughness of a city that has  flat walls interspersed with window sills and with curbs, cars, and sidewalks. Surfaces that are relatively smooth tend to reflect radio waves in accordance with  the Fresnel-reflection direction, * so they give strong backscatter only when the look  angle is nearly normal to the surfaces. 
 16, pp. 23-26, October, 1973.  132. 
 TO 
 Guerci, Space-Time Adaptive Processing for Radar , Norwood, MA: Artech House, Inc., 2003. 99. B. 
 Bartram, R. A. Kropfli, and W. 
 FORE  CAN BE VERY USEFUL FOR COMPUTATIONALLY INTENSIVE STUDIES  SUCH AS SYSTEM OPTIMIZA 
 At the proper time, the switch is closed and the stored energy is quickly  discharged through the load, or RF tube, to form the pulse. During the discharge part of the  cycle, the charging impedance prevents energy from the storage element from being dissipated  in the source.  Line-type modulator. 
 However, this reduces the cover­ age of targets at low elevation angles.  Since the problem or multipath errors occurs for antenna beams which illuminate the  surface. one approach is to use three elevation beams. 
 4(% 
 RADARCFM HTTPWWWLPIUSRAEDUMEETINGSLPSCPDFPDFSEARCH CHANDRAYAAN 
 However, element-level DBF is usually cost prohibitive except for arrays with a  small number of elements. Hence, subarray-level DBF is frequently pursued because it  requires far fewer digital receivers. However, subarrays are not the best choice of array  architectures for a given number of DOF in an adaptive array. 
 TR-77-338 (DDC AD-A047 897), October 1977.  8. W. 
 The angular displacement of the antenna from  the aircraft heading is the drift angle, and the magnitude of the doppler is a measure of the  speed along the ground track.  The use of the two rearward beams in conjunction with the two forward beams results in  considerable improvement in accuracy. It eliminates the error introduced by vertical motion of  the aircraft and reduces the error caused by pitching movements of the antenna. 
 Scattering from the auroral region has been studied extensively using the SuperDARN  HF radar network initiated by Greenwald,17 and an auroral echo-scattering model has  been developed by Elkins104; this can be used to predict target obscuration when the  transmission path is through the auroral region. Provided the radar is well removed  from the auroral zone, the waveform can often be chosen so as to manipulate the clut - ter echoes within range-doppler space, unmasking targets hitherto obscured. Often  several waveforms with different repetition frequencies are interleaved to achieve this. 
 VOLTAGE POWER SUPPLY UNTIL THE VOLTAGE IS SAFELY ABOVE THE OSCILLATION RANGE  WHICH  IS TYPICALLY SOMEWHERE BETWEEN  AND  OF FULL  OPERATING VOLTAGE ! MODIFICATION OF THE HELIX SLOW 
 When a radar scans across a rough ground plane, however, the energy reflected to the receiver antenna does not remain constant. A dynamic canceler is required. A diagram and description of one such device are given in Ref. 
 Regenerative tracking, although more complex, provides certain very definite advantages in compensating forerrors occurring later inthecircuit. The elements ofaregenerative tracking circuit are shown inFig. 17.13b. 
 Ibsen, “Integrated GPS/INS/SAR/GMTI radar precision targeting flight test  results,” in Proceedings Institute of Navigation GPS-95 Conference , 1995, pp. 373–379. 50. 
 TO 
 AMBIGUITY RESOLUTION IN HIGH 02& IS PERFORMED BY  MODULATING THE TRANSMITTED SIGNAL AND OBSERVING THE PHASE SHIFT OF THE MODULATION ON THE RETURN ECHO -ODULATION METHODS INCLUDE VARYING THE 02&  EITHER CONTINU 
 The deri- vation of the expression assumes that a target extracts power from an incident wave and then radiates that power uniformly in all directions. Although the vast majority of targets do not scatter energy uniformly in all directions, the definition assumes that they do. This permits one to calculate the scattered power density on the surface of a large sphere of radius R centered on the scattering object. 
 W. B. Milway, “Multiple target instrumentation radars for military test and evaluation,” in Proc. 
 The resulting value for a is usually much smaller than cr° for the planet at vertical incidence and is larger than the values of cr° near grazing incidence (return from the limb of the planet). Relative Importance of Theory and Empiricism. The theory of radar ground return has been the subject of many publications. 
 ,AYER 3ANDWICH  -ULTIPLE 
 It is further assumed in the present example that the reflection coefficient r = -1. The  reflected wave suffers no change in amplitude, but its phase is shifted 180°. A reflection  coefficient of - 1 applies at microwave frequencies to a smooth surface with good reflecting  properties if the radiation is horizontally polarized and the angle of incidence is small. 
 18.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 Data Rate.  Data rate is proportional to the product of pulse repetition frequency  fP, the number of range samples NR (which is proportional to slant-range swath, plus  the uncompressed pulse length, and inversely proportional to range resolution), the  number of quantization bits NS  retained in each sample of the data, and a factor of 2 that  accounts for the in-phase (I) and quadrature (Q) components since both the amplitude  and the phase of the signal stream are required. Once resolution and swath are estab - lished, the number of bits per sample is the only parameter open to choice. 
 Small gains make a small correction in the direction of each detection. As a  result, the tracking filter is less sensitive to noise but is more sluggish to respond to  maneuvers—deviation from the assumed target model. Conversely, large gains pro - duce more tracking noise but quicker response to maneuvers. 
 D" 4AYLOR COMPRESSED PULSE RESPONSE  FOR EXAMPLE  THE FRE 
 Cumming, I.G.; Wong, F.H. Digital Processing of Synthetic Aperture Radar Data: Algorithms and Implementation ; Artech House: Norwood, MA, USA, 2005. 3. 
 E.: FM/CW Radar Signals and Digital Processing, National Oceanic and Atmospheric  Administration. Boulder, Colorado, NOAA Technical Report ERL 283-WPL 26, July, 1973.  40. 
 The abscissa of the velocity response curve can also be labeled in terms of doppler  frequency. The doppler frequency of the target can be calculated from  fV dR=⋅2 λ (2.3) where fd is the doppler frequency, in hertz; VR is the target radial velocity, in meters  per second; and l is the transmitted wavelength, in meters. It can be seen from  Figure 2.10 that the doppler frequencies for which the system is blind occur at mul - tiples of the pulse repetition frequency. 
  
 12.18 are captured in Figure 12.10  where gain loss vs. surface roughness (in lieu of phase  error) is plotted. The plot shows that for 0.10 dB gain  loss, the rms surface error must be less than 0.01 l. 
 25.9 Coverage  ...........................................................  25.10 Clutter Cell Area  ................................................  25.12  25.6 Doppler Relati onships  ............................................ 
 #/5.4%2-%!352%3   Ó{°Î£ 3,# CONFIGURATION IS NOT EFFICIENT  BECAUSE THIS LEADS TO THE MAXIMUM ENTROPY OR  AUTOREGRESSIVE METHODS THAT  BEING NONLINEAR PROCESSING  HAVE A HIGH PROBABILITY OF SPURIOUS PEAKS 0RACTICAL EXPERIENCES INDICATE THAT THE RESOLUTION LIMIT IS DETERMINED RATHER MORE BY  IMPLEMENTATION AND ENVIRONMENTAL FACTORS THAN BY THE PURE *.2 CONSIDERATIONS Ó{°ÇÊ /, - // 
 FREQUENCY AMPLITUDE NOISE CAUSES ERRORS ONLY IN CONICAL 
 That is, the automatic gain control  is made to act within the time of a few pulse widths: The IAGC acts something like a  pulse-width filter, permitting target pulses to pass and attenuating the longer pulses from  488INTRODUCTION TORADAR SYSTEMS SeaclutterhasaRayleighpdfwhentheresolution islow.(Alow-resolution radarinthis casemighthavea5°beamwidth andi-JlSpulsewidth.30)Withbetterresolution thepdfofsea clutterdeviates fromRayleigh andthelog-FTC receiver isnolongerCFAR.Avariant sometimes usefulforreducing thefalse-alarm rateinnon-Rayleigh clutteristhelog-log receiver. Thisisalogarithmic receiver inwhichtheslopeofthelogarithmic characteristic progressively declines byafactorof2toiovertherangefromnoiselevelto+80dB.30.31 (Thisassumes thatthenormallog-FTC hasalogarithmic characteristic from-20dBbelow thereceiver noiseto+80dBabovenoise.)Inthelog-logreceiverthehighercluttervalues (tailsofthedistribution) aresubjected togreatersuppression. Adaptive videothreshold. 
 50.Senf.H.R.:Electronic Antenna Scanning, Proc.Natl.Conf.onAeronaut. Electronics (Dayton. Ohio). 
 Radar Block Diagram. The basic parts of a radar system are illustrated in the simple block diagram of Fig. 1.1. 
 TABLE 12.1 Scattering Coefficient Variation Small-Perturbation and Two-Scale Models. Recognition that existing models were inadequate for describing ocean scatter led to recognition that resonance of the signal with small structures on the surface has a powerful influence on the strength of the signal received.45'46 Thus a small-perturbation method originally proposed by Rice47 became the most popular way to describe ocean scatter. Its application to land scatter was not far behind. 
 522–528, July 1985. 31. W. 
 ! MODE SUITE . 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar.  TRACKING RADAR  9.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 Monopulse radar was developed to provide simultaneous offset antenna beams for  comparison of target echo amplitudes on a single pulse independent of echo signal  amplitude fluctuations. However, few microwave devices and components were ini - tially available, and the first monopulse systems were complex and resulted in cum - bersome and inefficient antennas. 
 These single horizontal-horizontal (HH) polarization images covered a 50 ×50 km area, see the red rectangle in Figure 1. Main parameters of Radarsat-2 WUF SLC data are detailed in Table 1. The Shuttle Radar Topography Mission (SRTM) 90 m DEM is used to simulate and remove topographic phases. 
 The phase shift for proper operation when propagating in the reverse Jirection is obtained by  simply reversing the polarity of the drive pulses. This reverses the direction of magnetization of  the ferrite toroid, which is equivalent to reversing the direction of propagation. Nomcciprocal  phase shifters cannot be t1-;cd in reflectarrays (Sec. 
 ¤ ¦¥³ µ´    Y YSINEWAVE 2AYL  EEIGH   WHERE V    ENVELOPE VOLTAGE  X   MEAN SQUARE VOLTAGE  !   SINE 
 To proceed further, it is necessary to indicate the summation index and its bounds. Let it be assumed that the transmissions radiated are a sequence of pulses with time intervals between pulses that are multiples of T. Then the variable x can be given as an integral multiple of the distance vT moved between successive transmissions. 
 Military sitmft carry sex, navigator who can take Gee readings and sure fixes  Civil aircraft always carry as small a crew i possible my  for obvious reasons, and the desire has been strongly expressed that all navigational aid should be preseratedil direct to the pilot,  . XII. TRAVEL BY BEACON  HERE ARE RIVAL SCHOOLS OF THOUGHT IN RADAR,  Some people like to see things; others are content  to let things guzde them by beacons and other impersonal  _aids. 
 The simulation parameters of Figure 12. Parameters V alues Radar look direction 0◦,9 0◦, 180◦, 270◦ Incidence angle 25◦ Radar frequency C-band Polarization HH Platform height 800 km Platform velocity 7455 m/s Wind direction 225◦ Wind speed 6 m/s Rotation direction of current ﬁeld counterclockwise Maximum Current velocity 1 m/s In Figure 12, the red arrows represent the four different look directions, the black arrow represents the wind direction and the blue arrow indicates that the rotation direction of the eddy current ﬁeld is counterclockwise. As shown in Figure 12a–d, the eddy spirals present different brightness variations, which are obviously related to the radar look directions. 
 LLOG  33)& !$#    WHERE 3)&3!$# IS THE RATIO OF NOISE POWER SPECTRAL DENSITY OF THE !$ CONVERTER INPUT  SIGNAL TO THE POWER SPECTRAL DENSITY OF THE !$ CONVERTER 4HE DEGRADATION OF OVERALL  SENSITIVITY DUE TO THE !$ CONVERTER NOISE IS GIVEN BY   ,D"    LOG   3!$#3)&    &)'52%  )& SAMPLING NOISE SPECTRUMS  
 60,  pp. 13H 140, March. 1954. 
 J. Tierney, C. M. 
 STEERING THE SPACECRAFT SO THAT THE ANTENNAS BORESIGHT IS ALWAYS DIRECTED TOWARD ZERO DOPPLER 4HIS ORIENTS THE VERTICAL PLANE OF THE AZIMUTH BORESIGHT TO BE ORTHOGONAL TO THE NADIR TRACK ON THE SURFACE  RATHER THAN TO THE ORBIT PLANE 7HEREAS 3!2 DATA FROM BOTH ARRANGEMENTS CAN BE PROCESSED INTO SATISFACTORY IMAGERY  MORE DEMANDING APPLICATIONS SUCH AS RADAR INTERFEROMETRY ARE BETTER SERVED BY YAW 
 TIME PROCESSING v IN )%%% .ATIONAL  2ADAR #ONFERENCE   PP n  * 7ARD  h3PACE 
 What was needed, clearly, was an instrument to show  ‘terrain clearance,’ which is the true distance from the  aircraft to the nearest part of the earth’s surface, with  some sort of warning indicator, so that if this aircraft-  to-earth clearance became dangerously small the pilot  could gain height and avoid danger. This the aneroid-  type altitude indicators could never do, for weather and  various barometric changes might result in a long-  distance aircraft returning to base with its altimeter  in error by several hundreds of feet.  Normal pulse-and-echo radar systems have a disad~  vantage in that at very close distances from the ground  _ the time interval between pulse and its echo becomes  extremely small, so there is a minimum height at which  such equipment can be used. 
 A portion of the frequency-modulated transmitted signal is applied to a  mixer along with the oscillator signal. The selection of the local-osciHator frequency is a bit  different from that in the usual superheterodyne receiver. The local-oscillator frequency flF  should be the same as the intermediate frequency used in the receiver, whereas in the conven­ tional superheterodyne the LO frequency is of the same order of magnitude as the RF signal. 
 49. Peebles, P. Z., Jr.: Multipath Angle Error Reduction Using Multiple-Target Methods, IEEE Trurls.,  vol. 
 radar-designated VHF/UHF  channels and are a penalty for exploiting broadcast transmitters of opportunity . ch23.indd   31 12/20/07   2:21:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 CW radars  simply observe the doppler shift between the carrier frequency of the return signal  relative to the transmit signal. Pulsed systems measure doppler by using a coherent  train of pulses where there is a fixed or deterministic phase relationship of the carrier  frequency between each successive radio frequency (RF) pulse. Coherence concen - trates the energy in the frequency spectrum of the pulse train around distinct spectral  lines, separated by the pulse repetition frequency (PRF). 
 TO 
 Bahr, A. J., and J. P. 
 IT-14, pp. 734–743,  September 1968. 19. 
 However, one might deduce from Figure 15.21 that sharp things (like wedges)  dominate the clutter at small grazing angles, flat things (like facets) at large angles,  and generally rough things at the intermediate angles. The theory of scattering from breaking waves referenced in connection with  Figure 15.20 was originally motivated by an attempt to explain the complex  behavior of sea spikes at low grazing angles observed by Lewis and Olin.40 This  theory was based on the plume model  of the most common spilling  breaker, in  which a water plume is emitted at the spilling crest and moves down the front  face;110 the scattering behavior was supplied by multipath illumination involving  reflections from the face of the wave.57 The elaboration of this model explained  much of the complex behavior of the observed sea spikes; however, like all other  models based on scattering features, it was necessary to make assumptions about  the sizes, shapes, and lifetimes of the scattering plumes. These parameters were all  inferred from observation of real sea surfaces, and the resulting predictions were  surprisingly good. 
 oritmighttrackthe"image"inthegroundinsteadofthetruclargct.Theowralldfcctonthe trackerissomewhat analogous to..glint"(Sec.5.5). 12.3THEROUND EARTH .J Ingeneral.thecurvature oftheearthcannotbeneglected whenpredicting radarcoverage. This isespecially trueforcoverage atlowelevation anglesnearthehorizon. 
 Only the response of the filter providing the largest improvement is plotted at each target doppler. For comparison the optimum curve from Fig. 15.18 is shown by a broken line and thus provides a direct assessment of how well theREALTlVE DOPPLER SHIFT fT FIG. 
 BAND SOURCE OF STRONG INTERFERENCE EG  OTHER RADARS  46 STATIONS  OR MICROWAVE COMMUNICATION LINKS  THAT  IF ALLOWED TO REACH THIS POINT  CAN EITHER OVERLOAD THE MIXER OR BE CONVERTED TO )& BY ONE OF THE SPURIOUS RESPONSES OF THE MIXER )DEAL MIXERS IN A SUPERHETERODYNE RECEIVER ACT AS MULTIPLIERS  PRODUCING AN OUTPUT  PROPORTIONAL TO THE PRODUCT OF THE TWO INPUT SIGNALS %XCEPT FOR THE EFFECT OF NONLINEARI 
 L. Schwartzman, and A. E. 
 Out-of-band IMD arises from nonlinear mixing  of two (or more) strong interferers such as broadcast stations, where the powerful  signals enter the front end of the receiving system and generate IMD products within  the radar signal bandwidth before they, the original interferers, are rejected by selec - tive filtering.120,121 Cross-modulation.  Cross-modulation involves nonlinear mixing of a strong  interferer with the received radar echoes, transferring the interferer modulation onto  the radar signal.120,121 In-band Inter-modulation.  A single resolution cell in the radar footprint may  have an area of 50–500 square kilometers, and there may be hundreds of cells  in the radar footprint, so using representative values of target RCS (Figure 20.9)  and surface scattering coefficient σ° (Figure 20.14), the signal-to-clutter ratio in  an OTH radar receiver may be as low as –80 dB for systems employing FM-CW  waveforms. 
 Soule, Jr.: Digital Generation of Wideband LFM Waveforms, IEEE Int. Radar Conf. Rec., pp. 
 CONTROLLED TUBE FOR RADARS IN THE PAST AT (&  6(&  AND 5(& )T IS STILL OF VALUE FOR  APPLICATIONS IN THESE FREQUENCY REGIONS AND SHOULD BE CONSIDERED AS A CANDIDATE WHEN DESIGNING A RADAR TO OPERATE AT THE LOWER FREQUENCIES 4HE CONSTANT EFFICIENCY AMPLI 
 SCAN DATA AND THE SAME CORRECTED FOR SPREADING LOSS AND ATTENUATION ARE SHOWN IN &IGURE  AND &IGURE  !LTHOUGH A # 
 The transmitter must be of adequate power to obtain the desired radar range, but it must  also satisfy other requirements imposed by the system application. The special demands of  MTI (moving target indication), pulse doppler, CW radar, phased-array radar, EMC  CHAPTER SIX RADAR TRANSMITTERS ., 6.1INTRODUCTION Theradarsystemdesigner hasachoiceofseveraldifferent transmitter types,eachwithitsown distinctive characteristics. Thefirstsuccessful radarsdeveloped priortoWorldWarII employed theconventional grid-controlled (triodeortetrode)vacuumtubeadaptedforopera­ tionatVHF,arelatively highfrequency atthattime.Themagnetron oscillator, which triggered thedevelopment ofmicrowave radarinWorldWarII,hasbeenoneofthemost widelyusedofradartransmitters, especially formobilesystems. 
 ANALOG $!  CON 
 Xispointbeingswitched. Tislengthofopen interval. Aismaximum amplitude ofsignal atX. 
 A. tlyland of the Naval Research Laboratory.' It was made accidentally while he was  working with a direction-finding apparatus located in an aircraft on the ground. The transmit-  ter at a frequency of 33 MHz was located 2 miles away, and the beam crossed an air lane from  a nearby airfield. 
 57. J. A. 
 Critical to the selection of these operating regions is the value of the bistatic radar constant k that is available. Many of the terms in Eq. (25.3) are transmitter-controlled. 
 Skolnik, M. I.: Nonuniform Arrays, chap. 6 in "Antenna Theory, pt. 
 Ilwr. Nariyutiotr (Lorldof~),  vol. 7. 
 In general, they require  less processing and memory to implement similar functions. It is also easier to imple - ment some filter responses as IIR rather than FIR filters. However, without careful  design, IIR filter responses can be very sensitive to coefficient quantization limitations  and could exhibit a tendency to overflow  (i.e., produce an output that exceeds the proces - sor dynamic range, determined by the number of bits in the datapath). 
 Johnston, “Tracking radar electronic counter-countermeasures against inverse gain jam - mers,” IEE Int. Conf. Radar–82 , Conf. 
 Radar System Engineering  Chapter 3 – The Radar Equation  14     The impinging radiated power is scatted by the target object and is dependent on shape, size, m a- terial or orientation of the object.  The measure of scattered power in d irection of the Radar is the  scattering cross section σ/m2 of the object.  With this, from the target to the transmitter the power  Pt is scattered. 
 2.14 OTHER CONSIDERATIONS  Prediction of radar range. In this chapter, some of the more important factors that enter into  the radar equation for the prediction of range were briefly considered. The radar equation  (2.1), with the modifications indicated in this chapter, becomes  Pa, G Ap, crnEi(n)  Rk,, = (4~)'kTo Fn(Br).fp(SIN), Ls  62INTRODUCTION TORADAR SYSTEMS 2.13PROPAGATION EFFECTS Inanalyzing radarperformance itisconvenient toassumethattheradarandtargetareboth locatedinfreespace.However, thereareveryfewradarapplications whichapproximate free-space conditions. 
 * *&(   $! +&+) 
 Dummer, devices  which enable pilots and radar operators to ‘fly’ thousands  of miles by radar without moving from a seat at a desk;  these trainers allow operational men and women to learn  their task through robot apparatus which simulates  travel by sea and air. With these radar devices for  training risk of human life is reduced, and much money  time, and fuel are saved.  It was not possible to tell this story of radar while we  were all bound by the essential needs of wartime secrecy;  credit could not be given to the men who really did the  jobs that mattered. 
 if the Jo term were used, it would enhance the leakage signal and reduce the target  signal. a condition opposite to that desired.  An examination of the Bessel functions (Fig. 
 6.) 2. George, T. S.: Fluctuations of Ground Clutter Return in Airborne Radar Equipment, Proc. 
 BASED .,&-  WITH K   o 
 For example, a greater number of filters can be realized by extending the  received data with extra zero values (also known as zero padding) after the received  returns have been appropriately weighted in accordance with the desired filter  response (e.g., Chebyshev). Filter Bank Designs Using Constrained Optimization Techniques.  For a  greater numbers of pulses in the CPI, and when the economy of the FFT implementa - tion of a doppler filter bank can be replaced by a FIR implementation, more desirable  FIR filter responses can be realized through the use of appropriate numerical digital  filter design techniques. 
 Earth Obs. Remote Sens. 2018 ,11, 1509–1519. 
 RADIUS FACTOR  K  SUCH THAT  AK AE     K MAY BE COMPUTED USING   KAD ND H   ;   =    WHERE DNDH  IS THE VERTICAL REFRACTIVE INDEX GRADIENT 5SING THE MEAN 
 Unfortunately, thethinskinrequired forgoodelectrical properties isnotconsistent withgood mechanical properlies. Thislimitsthesizeandthefrequency ofoperation ofthin-wall rigid radolllcs. Ground-based radomes lIlayutilizefoammaterials, suchaspolyester polyurethane. 
 SIDELOBE SYSTEM  EACH OF THESE POWER 
 DELAY CANCELLATION #OMPENSATION 
 Finally, 6657 highly coherent points were selected. Figure 7. Study area on multi-temporal google maps. 
 George, “Fluctuations of ground clutter return in airborne radar equipment,” Proc. IEE  (London) , vol. 99, pp. 
 Theotherapproach simultaneously transmits twofrequencies ItandI2.andthereceiveristunedtoastrongcross-product suchas2ft±f2.Whenreceiving atafrequency different fromthattransmitted, caremustbeexercised toensurethatthe transmitter signaldoesnotradiateasignificant spectralcomponent atthefrequency towhich thereceiver istuned. Theamount ofsignalreturned fromanonlinear contactataharmonic frequency isa nonlinear function oftheincident fieldstrength. Thusthenonlinear targetcrosssection depends onthepower,andthenormalradarequation doesnotapply.Inonesystemformula­ tiontherangedependence variedasthesixthpowerinsteadofthefourthpower.soHighpeak powerismoreimportant withsuchtargetsthanishighaveragepower. 
 The peak value is dependent on several factors including surface  roughness (which, in part, determines the value of r), servo bandwidth, and antenna  characteristics in the region. The errors are severe, and with un-smoothed track  (wide  servo bandwidth), the radar can break lock and lose track of the tar get. When the surface is rough, corresponding to a reflection coefficient of about 0.3,  the characteristic of the error versus elevation changes is observed in Figure 9.28. 
 A separate set of filters is required for each range gate. A consequence of the high  prf of the pulse doppler radar is that there are fewer range gates so that fewer sets of filter-  banks are needed. In sonie pulse-doppler radars, the duty factor might be as high as 0.3 to 0.5  so tliat only oric sct of filters is needed. 
 PLUS MODEL INCLUDING BREAKING WAVES AFTER  +UDRYATSEV ET AL Ú 4HE !MERICAN 'EOPHYSICAL 5NION   .   3%! #,544%2  £x°ÎÎ 3CATTERING BY 3URFACE &EATURES  ! BREAKING WAVE  WITH PLUMES OF WATER CAS 
 Both search and beacon AFC systems areofthesearch-and-lock type (Sec. 12.7). Asawtooth generated bythe recovery ofthe grid circuit ofablocking oscillator, V5, sweeps the reflector voltage and thus the frequency ofaklystron. 
 51. F. B. 
 3.8. Quantitative measurements of the target-to-clutter enhance­ ment of this technique are not known, but it has been said 59 that" small targets moving in one  direction could be easily detected in the presence of clutter signals exceeding the target return  by many orders of magnitude." The effectiveness of this technique is limited by the degree of  symmetry of the clutter spectrum, the need for a sufficient averaging time, and by the assump­ tion that the clutter fluctuations are large compared to other factors that might affect the  symmetry of the receiver spectrum.  Clutter fence. 
 G. Wieler, “Terminal doppler weather radar,” Microwave J. ,  vol. 
 7.45  7.7 Bandwidth of Phased Arrays  ..................................  7.49  Aperture Effects  .................................................  7.49 Feed Effect  ........................................................ 
 VIEW OF 0/ IS PROVIDED HERE TO ENABLE AN UNDERSTANDING OF THE FUNDAMENTALS OF THE METHOD 4HE 0/ METHOD CAN BE BROKEN INTO TWO STEPS   THE CAL CULATION OF INDUCED  REFLECTOR SURFACE CURRENTS  AND   THE INTEGRATION OF THESE CURRENTS WITH AN APPROPRIATE FREE SPACE VECTOR 'REENS FUNCTION KERNEL  TO DETERMINE THE FAR 
 Rortrt7  Air I)c~r.t~lopn~(~t~t ( 'c~rr/c'r 7'ec.lrtric.cll I)oc-rrrrterrtur~~ Report No. R ALK-7'DR-64-421, Deceni ber. 1964. 
 Additional attenuation may be programmed either manually via operator  control or automatically to increase the receiver’s large signal handling capability or  to reduce its sensitivity. Gain Normalization.  Receiver gain can vary due to component tolerances, fre - quency response, variation with temperature, and aging. 
 This loss is due to the filter not being  matched to the received waveform; that is, the filter is said to be mismatched. Thus to reduce  the sidelobes to a level of -30 to -40 dB results in a loss in peak signal·to-noise ratio of from  one to two dB. For many applications the beam broadening and the loss in peak signal-to­ noise ratio due to mismatch are usually tolerated in order to achieve the benefits of the lower  sidelobes. 
 Thus with forward bias the diode resembles a  low-value resistor. If the diode is housed in a package, the parasitic elements introduced by the  package degrade the switching action and influence the voltage breakdown and thermal  characteristics.  The variable capacitance semiconductor element, or l'Gractor diode, also can be used as  the switch in a diode phase shifter. 
 (4.23) is small, the exponential term can be replaced  hy the first two terms of a series expansion, or  f/ f/ ).2 af/ CA=----= = -- (4.24) · 4rr2a; 16rr2a~ 2rr2Ja2  where f,,. the pulse repetition frequency, has been substituted for 1/T. The average gain  (So /S,)a,·• of the single delay-line-c:111celer can be shown to be equal to 2. 
 A RADAR RANGE 
 STATIC SURFACE WAVE RADAR  FF KKSCAT INC 
 West and M. A. Sletten, “Multipath EM scattering from breaking waves at grazing inci - dence,” Radio Sci ., vol. 
 10. Zhao, Y.; Lin, Y.; Hong, W.; Yu, L. Adaptive imaging of anisotropic target based on circular-SAR. 
 13. M. Streetly, Radar and Electronic Warfare Systems , 1999–2000, 11th Ed., Coulsdon, Surrey, UK:  Janes Information Group, 1999, pp. 
 The  practical limits of standard centimetric equipment, how-  ever, remain 10 centimetres (frequency 3000 megacycles)  and 3 centimetres (frequency 10,000 megacycles). Use  of these shorter wavelengths allows the production of a  very narrow beam without the use of very cumbersome  and complicated aerials and reflectors. There is, per-  haps, an apt parallel in sound and light. 
 D  4HUS  FOR A SINGLE WAVE  WE NEED ONLY HAVE THREE INDEPENDENT PARAMETERS )N RADAR  WE  MUST CONSIDER BOTH TRANSMITTED AND RECEIVED POLARIMETRIC SIGNALS  SO THE NEED FOR FOUR MAGNITUDES AND TWO PHASES !NOTHER WAY TO DESCRIBE POLARIMETRIC SIGNALS IS TO USE THE MATRIX OF 3TOKES  PARAMETERS   & § ©¨ ¨ ¨ ¨¶ ¸· · · · 
 Analysis of clock jitter e ﬀects on LFM-signal pulse compression based on matched ﬁlter. In Proceedings of the 2018 2nd IEEE Advanced Information Management Communicates, Electronic and Automation Control Conference (IMCEC), Xi’an, China, 25–27 May 2018. 28. 
 Skolnik  (ed.), New York: McGraw-Hill, 1970. 39. E. 
 SURFACE HEIGHT 33(   
 D. Garrett, W. C. 
 Therefore, we can expand the dataset seven times. The data are divided into two sets: the training data set Dtrain1 (with 1440 samples) and the validation data set Dval1 (with 560 samples). Samples are shown in Figure 11. 
 It can  be seen that a = c2/8cr;. The rms velocity spread a, is usually the preferred method for  describing the clutter fluctuation spectrum.  The improvement factor can be written as  where S,/C, = output signai-to-clutter ratio, Si/Ci = input signal-to-clutter ratio, and  CA = clutter attentuation. 
 Of course,  the antenna—the radar’s “polarization gateway”—must be able to receive, and pos - sibly also to transmit, on more than one polarization. In general terms, there are four options available for polarimetric diversity in a  space-based SAR. These are: (1)  Single (monostatic) polarization  Typical of all dedicated spacecraft SARs  (until the launch of ENVISAT) with either HH or VV polarizations. 
 414–421, July 1963. 23. E. 
 E[().)2]1/2'1=1-­2s E L-r Direction ofpropogotion(7.21) Figure7.19Plan,elevation, andend viewsofaconverging lensantenna constructed fromparallel-plate wave­ guide.(E-plane metal-plate lens.). RAI)AR ANTENNAS 251  tvl~ere A is tlie wiivclerigtli ill air. f'qtlatiori (7.21) is always less tliati unity. 
 The echo signals for each interpulse  period can be stored in the digital memory with reference to the time of transmission. This  allows more elaborate stagger periods. The flexibility of the digital processor also permits more  freedom in the selection and application of amplitude weightings for shaping the filters. 
 WIDTH MODULATION1  QUADRATURE2#3  RADAR CROSS SECTION2&)  RADIO FREQUENCY INTERFERENCERMS  ROOT 
 HORN  MONOPULSE FEED.   42!#+).' 2!$!2   °x VOLTAGE PROPORTIONAL TO THE MAGNITUDE OF THE  3 SIGNAL OR  ¨3 ¨FOR THE !'# OF ALL THREE )&  AMPLIFIER CHANNELS 4HE !'# MAINTAINS CONSTANT ANGLE 
 32–11, 32–12. ch12.indd   41 12/17/07   2:32:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
   39.4(%4)# !0%2452% 2!$!2   £Ç°£Ç WHERE 04X 
     $     
 (3) In a MIMO array, the physical imperfections cause statistical deviations δFTX,δFRXof the transmitting and the receiving array factors from the ideal ones; ignoring second order terms, the total deviation δFMIMO from the ideal MIMO array factor can be expressed as: δFMIMO/similarequalδFTX·FRX+FTX·δFRX. (4) Thus, in a MIMO array the SLL distribution is strongly dependent on the transmitting and the receiving array factors: SLL MIMO/similarequal|FRX|2/angbracketleft|δFTX|2/angbracketright+|FTX|2/angbracketleft|δFRX|2/angbracketright+/Rfractur[/angbracketleftδFTX·δF∗ RX/angbracketrightδFRX·δF∗ TX]. (5) If the errors on the transmitter and the receiver are uncorrelated then the third term of this expansion vanishes. 
 The number of signal samples integrated is N9 the number of extraneous noise sam- ples integrated is Af, and the collapsing ratio p = (N + M)IN. • Most automatic detectors are required not only to detect targets but to make angular estimates of the azimuth position of the target. Swerling6 calculated the standard deviation of the optimal estimate by using the Cramer-Rao lower bound. 
 Sensors 2017 ,17, 2770. [CrossRef ][PubMed ] 20. Zhang, Y.; Liu, Y.; Jin, M.; Jing, Y.; Liu, Y.; Wei, S.; Wei, J.; Chen, Y. 
 High clutter rejection is usually achieved  through the use of pulse doppler waveforms in the first few elevation beam positions.  ch13.indd   54 12/17/07   2:41:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Transistor amplifiers with excellent noise figures are available to K11 band. Traveling-wave tubes are expensive. In many cases, the determining factor in deciding against a low-noise RF amplifier has been the presence of spillover noise, clutter signals, and signals produced by electronic countermeasures that equal or exceed the noise contributed by conventional front ends. 
 23, 1980. 7. Easton, R. 
 16.15] THESTABLE LOCAL OSCILLATOR 661 quencies and different oscillators. Ifthis coupling istooloose, frequency instability will result. Ifthecoupling istootight, tuning will bedifficult and thepower output from thelocal oscillator will bereduced. 
 Houghton. F. W. 
 The extremely low-level echo signals coming through the TR tube must beconverted tothe intermediate frequency and amplified considerably before being transmitted toa remote point. The local oscillator must beclose, because the AFC is based onacomparison ofthefrequency ofthelocal oscillator and that of the ruagnetron. Electrical and functional considerations dictate, then, that thefollow-. 
 By equating  this ptiase difference to the phase shift obtained from a line of length I, as given by Eq. (8.16),  we have  277(1l/A) sin U0 + 2nrr1 = 21cl/A (8.17~)  When the beam points broadside, (00 = 0), Eq. (8.176) yields m = [/Ao, where A, is defined as  the wavelength corresponding to the beam position at broadside. 
 T. K. Johnson, R. 
 1545-1546.  November. 1957. 
 TURES ARE CLOSELY RELATED TO HIGH RANGE RESOLUTION SIGNATURES A &OURIER TRANSFORM EASILY CONVERTS ONE TO THE OTHER   AND THEY SUFFER THE SAME ATTITUDE ESTIMATION LIMITATIONS 4HE PRINCIPAL ADVANTAGE TO -&2 IS THAT MANY DEPLOYED RADARS HAVE MU LTIPLE CHANNELS AND  SWITCHING BETWEEN THEM ON A SINGLE TARGET IS RELATIVELY EASY ! SIMPLIFIED VERSION OF THE RECOGNITION PROCESS IS SUMMARIZED IN &IGURE  $OPPLER SIGNATURES REQUIRE HIGH DOPPLER RESOLUTION  WHICH IS USUALLY EASILY ACHIEVED  AND LIMITED ONLY BY DWELL TIME 4HE INDIVIDUAL SCATTERERS  WHICH GIVE RISE TO DOPPLER SPREAD  ARE SMALL AND SO RECOGNITION IS USUALLY LIMITED TO A FRACTION  TYPICAL  OF MAXIMUM RANGE *ET ENGINE MODULATION *%-   A SUBSET OF DOPPLER SIGNATURES  IS AN EXCELLENT TARGET RECOGNITION METHOD %VEN AIRCRAFT  WHICH USE THE SAME ENGINE TYPE  OFTEN HAVE VARIATIONS IN THE ENGINE APPLICATION  SUCH AS THE NUMBER OF COMPRESSOR BLADES OR NUMBER OF ENGINES  WHICH ALLOWS UNIQUE TYPE RECOGNITION 4HE REAL PICTURE OF *%- IS NOT SO CLEAN BECAUSE OF MULTIPLE ON 
 - 
 UNITS PER KILOMETER ARE KNOWN AS NORMAL GRADIENTS &REE 
 I' II I !' I.. !' I','-11 I.:..' I . I -,-_.1-----'-__+. 
 The time constant of the differentiator is opera - tor-adjustable with a so-called rain clutter control, which allows the target-to-clutter  ratio to be optimized for the particular precipitation scenario. The vertical pattern of a shipborne navigational radar antenna needs to be rela - tively wide to cope with the ship’s pitch and roll, which is assumed to be a maximum  of ±10°. (Use of a stabilized platform would not meet the market’s price demands.)  This limits the vertical beam-shaping that can be used to reduce both precipitation  clutter and vertical lobing effects. 
      
 17). Some radar systems that integrate many pulses utilize a combination of coher- ent and noncoherent integration when the phase stability of the received pulses is sufficient for some coherent integration but not great enough to allow coherent integration of the entire pulse train during the antenna on-target dwell time. If the total number of received pulses is Af and M of them (with M < N) are coherently integrated and if the coherent integrator is followed by a noncoherent integrator, then (assuming an appropriate implementation and ideal integrations) the detectability factor will be %M,N) = Dv(NIAf)IM (2.28) where D0(M,AO means the detectability factor for the assumed combination of co- herent and noncoherent integration and D0(NIM) is the detectability factor for noncoherent integration of NIM pulses with no coherent integration (e.g., a value read from curves such as those of Figs. 
 Also, the inte- grated pulses are then all of the same amplitude (except for the effect of target fluc- tuation), and so there is no pattern loss of the type described in Sec. 2.7. There is, however, a statistical loss if the target direction and the antenna beam maximum do not always coincide when the pulses are radiated. 
 79.Currie.N.C.f.B.Dyer,andR.D.Hayes:SomeProperlies ofRadarRelurns fromRainat9.375.35. 70,and95Gltz,IEEE1975IIIlel"/wtiC)/llIlRadarCc)/!(en'llce. i\pr.2123.1975.i\rlington. 
 The conventional technique for achieving azimuth resolution has been that of radiating a narrow beam. In this case the resolution of a target depends upon whether the target is included within the half-power points of the radiated beam, although some techniques exist for resolving targets somewhat less than a beamwidth apart. The computation of the linear azimuth resolution for the conventional case is well known. 
 RECEIVERS, DISPLAYS, ANDDUPLEXERS 349 recovered bysubtracting theoutputsofthetwodiodemixers.InFig.9.2thebalanced diodes areshownreversed sothattheIFoutputs canbeadded.Local-oscillator noiseatthetwo diodemixerswillbeinphaseandwillbecanceled attheoutpuLIl isonlytheAMnoiseofthe localoscillator whichiscanceled. TheFMnoiseinserted bythelocaloscillator isunaffected by thebalanced mixer.9 Inasingle-ended mixer,themixingactiongenerates allharmonics oftheRFandLO frequencies, andcombinations thereof. 7Theoutputisdesigned tofilteroutthefrequency of interest, usuallythedifference frequency. 
 Apparatus Considerations. —Having blocked out the system and determined the leading design constants, wecan now proceed with the detailed engineering. Figures 5.6and 5.7show the final result; there follow afewremarks astothemore important ways inwhich theengineer- ingtechnique forthis system cliffersfrom that used inpulse systems. 
 MENTATIONS OFTEN UTILIZE EFFICIENT APPROACHES THAT MINIMIZE THE NUMBER OF CALCULA 
 H..andD.N.Ludington: AChargeTransfer DeviceMTIImplementation. IEEE1975 1,!Cenrat;ollal RadarCOII(erellce Record, pp.107-110, IEEEPublication 75CHO938-1AES. .~6.Roherts. 
 TION WHERE ONE ATTENUATOR IS GENERALLY AVAILABLE PER ELEMENT THUS ONE TAPER FUNCTION IS AVAILABLE TO ACHIEVE REASONABLE LOW SIDELOBES FOR BOTH SUM AND DIFFERENCE BEAMS  3UBSEQUENTLY A FIXED DIGITAL TAPER  AFTER THE FORMATION OF SUB 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 The terms active element pattern  and element impedance  refer to an element in  its operating environment (i.e., in an array with its neighboring elements excited). 
 ! DESIGN 4HE #LASS 
 The drop across the condenser Cand the lack ofunity gain inthe cathode follower (Sec. 13.10) are compensated bythe network composed ofCaand Rzwhich integrates thesawtooth appearing onthecathode ofVsand thus provides across C2acorrection proportional toL2. The sawtooth waveform is applied totheplate ofdiode Vs,whose cathode has apositive bias ofan amount determined bythesetting ofthedelay potentiometer. 
 (2.17) is equal to J(4/n) - 1 times tlie  mean valuc, arid for tile cxponeritial density of Eq. (2.18) tlie standard deviation is equal to wo.  'l'licrc ate otlicr pr ot~ability-density functions of interest in radar, such as the Rice, log norrnal,  arid tlie chi square. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft.  MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.416x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 in Figure 5.39. 
 ASV Mk. VIB had mostly the same features as ASV Mk. VIA. 
 TURES  SEPARATED HORIZONTALLY  TO CANCEL GROUND CLUTTER AND IMAGE A MOVING TARGET 4HEIR APPROACH IS A COMBINATION OF SPACE 
  RESULTS PP     )MAGING OF -OVING 4ARGETS IN 3!2 )MAGES  0ERRY ET AL HAVE DEVELOPED A METHOD  FOR 3!2 IMAGING OF GROUND 
 The klystron is another variety of ‘hollow-space  oscillator.’ Picture a CRT in which a beam of electrons  is drawn from the cathode to the positive anode. On  their way the electrons pass the lips of two rhumbatrons  —ring-like cavities connected together by concentric  pipes. The first cavity is known as the ‘buncher,’ as the  physical dimensions are arranged so that the electrons  do, in fact, cross the opening of the cavity in bunches,  in alternate ‘parcels’ of large and small electron density. 
 In this paper the need to design a transmit waveform, which results in a spectrum with lo w  amplitude ripple, is emphasized. For chirp type waveforms such low ripple designs can be achieved either through the use of a non -linear chirp with a carefully chosen characteristic, or  by slowing the rise - and fall -times of the transmitted chirp, or a c ombination of both. Accurate  control of the rise - and fall -time of a solid -state transmitter is, however, often quite difficult. 
 x°ÎÈ  2!$!2 (!.$"//+  !LTHOUGH AN -&!2 CONTAINS A VERY STABLE TIME REFERENCE  UNCERTAINTIES IN THE RATE  OF CHANGE OF TERRAIN HEIGHT  REFRACTION  WINDS ALOFT  AND VERY LONG COHERENT INTEGRATION  TIMES FORCE THE MEASUREMENT OF THE CLUTTER DOPPLER ERROR VERSUS PREDICTED FREQUENCY TO MAINTAIN PROPER FOCUS AND BIN REGISTRATION  AS SHOWN IN THE UPPER RIGHT IN &IGURE  ! SIMILAR FUNCTION IS PERFORMED IN 3!2 AS WELL 3YNTHETIC !PERTURE 2ADAR  !S IS THE CASE FOR $"3  3!2 IS A MULTIRATE 
 Thus  the clutter rejection notch needed to cancel clutter cannot be fixed, but must vary. The design  of an MTI is more difficult with an airborne radar than a shipborne radar because the higher  speeds and the greater range of elevation angles result in a greater variation of the clutter  spectrum.  In addition to shifting the center frequency of the clutter, its spectrum is also widened. 
 The inference is that for vertically polarized waves from a ra- dar, looking along the wind direction, cr° is constant for a specific radar operating frequency if the sea is fully developed. Further, following the analysis of Barrick,19 cr° will have the same value for all water-wave frequencies along the wind direction where the sea is fully developed. In general, the scattering coef- ficient will be proportional to the resonant waveheight squared. 
 Note that although an increasing number of clutter returns  are received during the charging period, the vector sum may actually decrease owing  to the random phase relations of the returns from different patches. If a clutter canceler (MTI filter) is used, the output cannot begin to settle to its  steady-state value until space charging is complete. Some settling time must be  allowed before signals are passed to the filter bank. 
 Azimuth patterns a and c are for a fixed elevation angle of -10°. The remaining patterns are in the elevation plane for fixed nose-on or tail-on azimuths. The first and second subscripts give trans- mitted and received polarizations; H and V indicate horizontal and vertical polarizations, and R and L indicate right circular and left circular polarizations. 
 D. Solomon, D. A. 
 148.) This regulated the 115-volt output toabout +0.1volt rms and had good response and temperature characteristics, but thediode was sensitive tovibration. A?@=% Inthelatter part of1944, more interest was shown inthedevelopment ofelectronic regulators because ofatrend toward the use ofengine- driven alternators that were toolarge forcontrol bycarbon-pile regulators unless separate exciter generators were used. The ATSC Equipment Division atWright Field sponsored the development oftwo regulators tocontrol and excite engine-driven alternators rated 8kva, l-phase, 400 to800 cps, 115 volts a-c. 
 cannot be conveniently set to a precise value of phase without special care in calibra­ tion over the desired range of temperature and frequency.)  Figure 8.5 illustrates the parallel-line configuration of the digitally switched phase shifter  in which the desired length is obtained by means of a pair of one-by-N switches. Each of the  boxes labeled S represents a SPST switch. The N ports of each one-by-N switch are connected  to N 1 ines of d irf eren t lengths / 1, / 2, ... 
 Theshapingofthebeamisgenerally inoneplane,withanarrowpatternofconventional. - . -- - . 
 Let’s look at the direct DDC in the time domain first, for intuition, and then we can  carefully derive the architecture in the frequency domain. Suppose the DDC archi - tecture is as sketched in Figure 25.11, with an IF centered at 75 MHz and a 75 MHz  LO and suppose the NCO is set to 300 MHz so that it produces the sampled sines and  cosines shown in Figure 25.12 a, where vertical lines and dots indicate sample times  and values, respectively. Because the sample rate is four times the LO frequency, the  (cos, -sin) LO sample pairs cycle repeatedly through (1, 0), (0,–1), (–1, 0), and (0, 1). 
 Ci. W.. and A. 
 Moore16.1 16.1  Introduction / 16.1 16.2  Parameters Affecting Ground Return / 16.4 16.3  Theoretical Models and Their L imitations / 16.7 16.4  Fading of Ground Echoes / 16.12 16.5  Measurement Techniques for Ground Return / 16.19 16.6  General Models for Scattering Coefficient (Clutter Models) / 16.29 16.7  Scattering Coefficient Data / 16.35 16.8  Polarimetry / 16.46 16.9  Scattering Coefficient Data Near Grazing / 16.52 16.10  Imaging Radar Interpretation / 16.55 Chapter 17 Synthetic Aperture Radar Roger Sullivan17.1 17.1  Basic Principle of SAR / 17.1 17.2  Early History of SAR / 17.2 17.3  Types of SAR / 17.2 17.4  SAR Resolution / 17.6 17.5  Key Aspects of SAR / 17.10 17.6  SAR Image Quality / 17.16 17.7  Summary of Key SAR Equations / 17.21 17.8  Special SAR Applications / 17.22 Chapter 18 Space-Based Remote Sensing Radars R. Keith Raney18.1 18.1  Perspective / 18.1 18.2  Synthetic Aperture Radar (SAR) / 18.5 18.3  Altimeters / 18.29 18.4  Planetary Radars / 18.43 18.5  Scatterometers / 18.53 18.6  Radar Sounders / 18.59.     x Chapter 19 Meteorological Radar R. 
 Minute variations in amplitude  (AM) and phase (FM) can result in sideband components that fall within the doppler  frequency band. These can generate false targets or mask the desired signals. Therefore both  AM and FM modulations can result in undesired sidebands. 
 31. Trizna, D. B., and J. 
 SCAN  WILL RESULT IN A HYPERBOLOID OF REVOLUTION WHOSE  VERTICAL AXIS RUNS THROUGH THE TARGET ! PLANE ORTHOGONAL TO THE VERTICAL AXIS WILL GENER 
 Itisusuallyeasiertoseparate multiple targetsintherangecoordinate than inangle. Rallgeaccuracy. Ifaradariscapableofgoodrange-resolution itisalsocapableofgoodrange accuracy. 
 The mechanical packaging of the power combiner should allow modules to be repaired easily. The packaging should also provide short, equal phase and low- loss interconnections between the amplifier modules and the combiner. High-power combiners may be either reactive or hybrid (or equivalent magic-T) designs. 
 CENTERED COORDINATES AND FOR THREE 
 COMPARISON SYSTEM MORE SUSCEPTIBLE TO BORESIGHT CHANGE DUE TO MECHANICAL LOADING SAG   DIFFERENTIAL HEATING  ETC ! TECHNIQUE GIVING GREATER BORESIGHT STABILITY COMBINES THE TWO ANTENNA OUT 
 The switch initiates the start of the modulator  pulse by discharging the pulse-forming network, and the shape and duration of the pulse are  determined by the passive circuit elements of the pulse-forming network. Since the trailing  edge of the pulse depends on how the pulse-forming network discharges into the nonlinear  load, the trailing edge is usually not sharp ahd it may be difficult to achieve the desired pulse  shape.  The charging inductance Leh and the capacitance C or the pulse-forming network form a  resonant circuit, whose frequency of oscillation approaches Jo= (2nt 1(Lch Ct 112• (The  inductance of the pulse-forming network and the load are assumed small.) With a d-c energy  source the pulse repetition frequency JP will be twice the resonant frequency if the thyratron is  switched at the peak of maximum voltage. 
 Plonus, and E. F. Knott, “Designing foamed-plastic materials,” Microwaves ,  pp. 
 325 of ref. 85.)  39. Sims. 
 If tllc  main hcanl ca~lnot be rnade tiarrow bccaiise of constraints on the antenna size, an auxiliary  antenna can be ernployed to create a ~iotch in the main-beam radiation pattern in the direction  of the jammer. With adaptive circuitry similar to that of the sidelobe canceler, this rtic~ir~-hrclr~r  r~otc.l~ can be at~tomatically adjusted to be maintained in the direction of the jammer.  Mt~ltiple radars viewirlg tlie sanw coverage in a coordinated manner can provide some  benefit against a jammer since it is unlikely that jamming power can be distributed u~iiformly  in space. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 
 J. Purdy et al., “Radar signal processing,” Lincoln Laboratory Journal , vol. 12, No. 
 Remote Sensing , vol. 17, pp. 1803–1835, 1996. 
 PERFORMANCE RADAR SIGNAL PROCESSORS ARE USUALLY A HYBRID OF APPLICATION 
 Applica­ tionsforlimited-scan arraysinradarhaveincluded theone-dimensional electronic scanof3D radars(Sec.14.4),aircraftlandingorground-control approach (GCA)radars,'57andhostile­ weapon-location radars.' 58 8.11APPLICATIONS OFTHEARRAY INRADAR Thephased-array antenna hasbeenofconsiderable interest totheradarsystems engineer because itsproperties aredifferent fromthoseofothermicrowave antennas. Thearrayantenna takesseveralforms:. Mechanically scanne(1 array.Thearrayantenna inthisconfiguration isusedtoformafixed beamthatisscanned bymechanical motionofthe·entireantenna. 
 77. 122. A. 
 (AM.. 300Nfc/sec (FM) ..... (AM) .......... 
 12,   pp. 847–854, 1973. 40. 
 DEPENDENT     TRACKING ERRORS    DEVIATION OF ANTENNA    FROM TARGET "ORESIGHT AXIS COLLIMATION!XIS SHIFT WITH   2& AND )& TUNING   2ECEIVER PHASE SHIFT   4ARGET AMPLITUDE   4EMPERATURE 7IND FORCE !NTENNA UNBALANCE3ERVO UNBALANCE 2ECEIVER THERMAL NOISE    -ULTIPATH ELEVATION ONLY     7IND GUSTS    3ERVO ELECTRICAL NOISE   3ERVO MECHANICAL NOISE 2ADAR 
 In practice, tile sidelobe level of a Luneburg lens seetns to be in the vicinity of 20  to 22 dB.  When the full 4n radiaris ~f solid coverage is not required, a smaller portion of the lens can  be used, with a saving in size and  eight.^'.^^ The Luneburg-lens principlecan also be applied as  a passive reflector iri a niariner arialogous to a corner refle~tor.~' If a reflecting cap is placed  over a portion of tlie spherical lens, an incident wave emerges in the same direction from which  it eritered. The cap may be made to cover a sector as large as a hemisphere. 
 Both classes are of general applicability to HF communications and geo - physical investigations, as well as skywave radar. Models of the Ionospheric Medium.  Models of the ionosphere fall into two   categories: • Climatological models based on sounder, rocket, and satellite measurements. 
 Olster, W. Sabin, A. Freedman, and H. 
 Anadvantage claimed forthishybridtracking technique isthat,likemonopulse, target amplitude fluctuations donotaffectthetracking accuracy.Itisalsoclaimed thatthesimplicity ofconicalscanisretained. Bothclaimscanbedebated. Although onlytworeceivers are required insteadofthethreeusedinamonopulse tracker,themechanical rotation ofthetwo (1)g4.0..... 
 EFFECT OF SEA SURFACE ON RADAR BEAM With radar waves being propagated in the vicinity of the surface of the sea,themainlobeoftheradarbeam,asawhole,iscomposedofanumberofseparate lobes as opposed to the single lobe-shaped pattern of radiation asemitted in free space. This phenomenon is the result of interference betweenradar waves directly transmitted and those waves which are reﬂected from the surface of the sea. The vertical beam widths of navigational radars aresuch that during normal transmission, radar waves will strike the surface ofthe sea at points from near the antenna (depending upon antenna height andverticalbeamwidth)totheradarhorizon.Theindirectwaves(seeﬁgure1.4)reﬂected from the surface of the sea may, on rejoining the direct waves,either reinforce or cancel the direct waves depending upon whether they areinphaseoroutofphasewiththedirectwaves,respectively.Wherethedirectand indirect waves are exactly in phase, i.e., the crests and troughs of thewavescoincide,hyperboliclinesofmaximumradiationknownasLINESOFMAXIMA are produced. 
 If continuous sweep-length control isdesired, the circuits ofFig. 13.42 should besubstituted, the feedback voltages fortheturn-off circuit and forthesawtooth generator being taken from the cathode ofV15~. The sawtooth passes through the “phase-splitting” amplifier Vl,b, which provides signals ofboth polarities forthe push-pull sweep ampli- fiers. 
 present without knowing something about its location in space and its nature. The extraction of useful target information is therefore an important part of radar operation. The ability to consider detection independent of information extraction does not mean that there is no relation between the two. 
 cc 
 However, in the 1990s and 2000s, a number of systems have been developed that pro - vide phased array performance in an airborne platform. The Multi-Role Electronically  Scanned Array (MESA) radar developed by Northrop Grumman on a Boeing 737-700  for the Australian Wedgetail program is an example (see Figure 3.2). An alternate solu - tion that combines mechanical scanning in conjunction with electronic scanning is in  development with the AN/APY-9 radar for the E-2D aircraft (follow-up to the U.S. 
 Hence, for a ground-based system that is limited by scan rate, one should improve the  compensation pattern rather than use a higher-order MTI canceler. However, airborne  systems are primarily limited by platform motion and require both better cancelers and  compensation for operation in a land-clutter environment. In the sea-clutter environ - ment, the system is usually dominated by the spectral width of the velocity spectrum or  platform motion rather than scanning. 
 This permits  the transmitter power supply transient effects to be identical pulse to pulse and also,  particularly applicable to solid-state transmit devices, permits the device heating and  cooling to be identical from pulse to pulse. Sometimes constant duty cycle operation is  not possible, but there are various techniques that can be used to approach this desired  condition. Consider an MTD waveform where a CPI consisting of n pulses is transmit - ted with a constant PRI. 
 GER PULSES USED IN MANY MEASUREMENTS  THE VALUES OBTAINED ARE SOMETIMES POORLY DEFINED 3OME AUTHORS  USE A SCATTERING CROSS SECTION PER UNIT PROJECTED AREA RATHER THAN  PER UNIT GROUND AREA &IGURE  ILLUSTRATES BY USING A  SIDE VIEW THE DIFFERENCE  &)'52%     'EOMETRY OF THE RADAR EQUATION. 
 Eq. (8.10) states that the element spacing should be less than 0.54,t Note that antenna  elements used in arrays are generally comparable to a half wavelength in physical size.  Change of beamwidth with steering angle. 
 Land subsidence due to groundwater withdrawal in the northern Beijing plain, China. Eng. Geol. 
 AKS, P. P. Bogdanovic, and D. 
   PP  
 6, pp. 191–198, 1986. 65. 
 GULAR 
 48-55. January. 1977. 
 RESOLUTION CLUTTER MAPS ARE USED TO SUPPRESS THE  CLUTTER RESIDUES  AFTER DOPPLER FILTERING   TO THE RECEIVER NOISE LEVEL OR  ALTERNATIVELY  TO  RAISE THE DETECTION THRESHOLD ABOVE THE LEVEL OF THE RESIDUES  4HIS IN TURN ELIMINATES  THE NEED TO RESTRICT THE )& DYNAMIC RANGE  WHICH CAN THEN BE SET TO THE MAXIMUM VALUE SUPPORTED BY THE !$ CONVERTERS 4HUS  A SYSTEM CONCEPT IS OBTAINED THAT PROVIDES A CLUTTER SUPPRESSION CAPABILITY THAT IS LIMITED ONLY BY THE RADAR SYSTEM STABILITY  THE DYNAMIC RANGE OF THE RECEIVER 
 W. Schunk, “Parameterized ionospheric model: A global ionospheric parameterization  based on first principal models,” Radio Science , vol. 30, pp. 
 WIDTH ! FREQUENCY 
  D" RESPONSE RELATIVE TO AVERAGE RESPONSE  IS USED AS THE MEA 
 wliicli includes the effect of 7 percent rtlisrnatch as well as the effect of beat11  broaderiirig. I'lie rnore faces that are used, the greater can be the element spacing before the  oiisct of grating lohes. If it is required that the gains at the maximum scan angle be the sanie. 
 D.L.:Three-dimensional AirSurveillance Radar.Systems Technology, (Plessey Co,Hord. England). no.21.pp.29.1.1.June.1975. 
 NAS USUALLY HAVE A HIGH RESISTANCE TO CROSS 
 41,  pp. 770-774, June, 1953.  50. 
 437–448, 1992. 88. W. 
 The ISAR processing based on the fast minimum entropy phase compensation method iteratively obtains the phase error estimation by constructing a cost function of entropy. The experimental results based on spaceborne and airborne SAR data verify the effectiveness of the proposed method. Though the experimental results are good, the airborne SAR sub-images (resolution higher than 1 m) are not well focused via ISAR processing. 
 DIMENSIONAL &&4 IS PERFORMED FOLLOWED BY SPACE 
 Wardrop, “The role of digital processing in radar beamforming,” GEC J. Res ., vol. 3, no. 
 D.Reed.J.E.:TheAN/FPS-85 RadarSystem,Proc.IEEE,vol.57,pp.324-335, March, 1969. 24.(Jlasoe,G.N..andJ.V.Lebacqz: ..PulseGenerators," MITRadiation Laboratory Series,vol.5, McGraw-Hili BookCompany. NewYork,194R. 
 £Jectro11ics  Letters, vol. 9, pp. 121-122, Mar. 
 TO 
 (ORIZON 2ADAR  !N IMPORTANT DEFENSE 
  RADAR ADDRESSES THE !%7 RADAR SURVEILLANCE COVERAGE REQUIREMENTS  DISCUSSED AT THE BEGINNING OF THIS CHAPTER  UTILIZING A MECHANICALLY AND ELECTRONICALLY STEERABLE ANTENNA LOCATED IN A ROTODOME 4HERE ARE THREE SCANNING MODES OF OPERATION  &)'52%   -4) IMPROVEMENT FACTOR FOR A DOUBLE 
 This sum is  I= l  compared with a threshold as given by the right-hand side of Eq. (10.36). Therefore the  combined detector and integrator must have a law given by  y = In J0(av) (10.37) . 
 If an unknown doppler-frequency shift is experienced when a long  pulse, a noise-rriodulated pulse, or a pulse trait1 is reflected from a niovirig target, a receiver  tuned to the transmitted signal will not accept the echo signal if the doppler shift places the  echo frequency outside the band of the receiver rnatched filter. That is, the receiver may not be  tuned to the correct frequency. To circumvent this potential loss of signal, a bank of contig-  uous matched filters must be used to cover the range of expected doppler-frequency shifts. 
 TO 
 All sources of instability are included in this single measurement except for any  contributors outside the delay-line loop. It is important to recognize that timing jit - ter does not produce equal impact on all parts of the return pulse and generally has  minimal effect on the center of the pulse, so it is essential to collect data samples at  a multiplicity of points across the return, including leading and trailing edges. The  total radar instability is the ratio of the sum of the multiplicity of residue powers at  the output of the doppler filter to the sum of the powers at its input, divided by the  ratio of receiver noise at these locations. 
 Garrett, P. A. Lange, and S. 
 21.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 The intrinsic impedance h of a medium is the relationship between the electric  field, E, and the magnetic field, H, and is a complex quantity given by  ηωµ σ ω ε=− −j j (21.8) At the boundary between two media, some energy will be reflected and the  remainder transmitted. The reflected field strength is described by the reflection  coefficient, r:  r=− +η η η η2 1 2 1 (21.9) where h1 and h2 are the impedances of medium 1 and 2, respectively. The reflection coefficient has a positive value when h2 > h1, such as where an  air-filled void exists in a dielectric material. 
 D" WIDTH OF THE COMPRESSE D PULSE AT THE OUT 
 27. Morabito, A.F.; Palmeri, R.; Isernia, T. A Compressive-Sensing-inspired procedure for array antenna diagnostics by a small number of phaseless measurements. 
 It would also permit the resolution  j of two targets no matter how close together they were on the ambiguity diagram. Naturally, it  is not surprising that such a desirable ambiguity diagram is not possible. The fundamental  properties of the ambiguity function prohibit this type of idealized behavior. 
 The power loss is proportional to the square of the  distance between the r adars transmitter and the reflecting  obstacle. The expression for free -space path loss actually  encapsulates two effects. Firstly, the spreading out of  electromagnetic energy in free space is determined by the  inverse square law. 
 .OISE 
 18. Eher. L 0 .. 
 The gain with scanning,  therefore, is  GA( )cosqq 00 24=πλη (13.14) If the aperture is made up of N equal radiating elements and is matched to accept  the incident power, then the contribution to the overall gain is the same from all  elements, hence  G(q ) = NGe(q )h (13.15) where Ge is the gain per element. It follows from Eq. 13.14 that the matched element  power pattern is  GA Ne( ) cos q q =42πλ (13.16) and the normalized radiation amplitude pattern of the (matched) element or (matched)  element pattern  is  Ee( ) cosq q=  (13.17) For a given element spacing s, the total number of radiators N in the area A is N =  A/s2, and Eq. 
 MENT IS CONSIDERED FIRST ATTENTION IS THEN FOCUSED  ON THE FOLLOWING TOPICS MAIN 
 Cross-polarized scatter from smooth surfaces is much less near ver- tical than elsewhere. Figure 12.3295 shows this effect. Cross-polarized returns from volume scatterers with elements that are large compared with a wavelength are stronger than for surfaces, sometimes being only 3 dB down. 
  D"  EDGE TAPER IS IMPLEMENTED !LTHOUGH THE PLOT OF &IGURE  INC LUDES TAPER  BLOCKAGE   AND SPILLOVER LOSSES  THERE ARE ADDITIONAL LOSSES THAT MUST BE INCLUDED WHEN ASSESSING  THE OVERALL APERTURE EFFICIENCY 4HESE LOSSES  EG  FEED BLOCKAGE  SURFACE REFLECTION  FEED MISMATCH  AND RESISTIVE LOSSES  ETC  VARY FROM SYSTEM TO SYSTEM  BUT  D" IS TYPICAL 7ITH THESE ADDITIONAL LOSSES  THE OVERALL LOSS BECOMES  D" OR  APERTURE EFFICIENCY TYPICAL FOR A SINGLE REFLECTOR SYSTEM  3IDELOBE REQUIREMENTS MUST ALSO BE CONSIDERED !S SHOWN IN &IGU RE   FOR THE  SAME CENTER 
 192 INTRODUCTION TO RADAR SYSTEMS  The klystron amplifier provides the radar system designer wit 11 high power, Iiigh gain,  good efficiency, and stability for MTI and pulse-compression applications. It is probably the  preferred tube for most high-power radar applications if its high operating voltage and large  size can be tolerated. The traveling-wave tube is similar to the klystron. 
 Perry et al .50 © IEEE 1999 )(a) Conventional SAR Processing (b) Keystone Processing Range Cross Range 1010Tractor Trailer Moving at 17 mph on Straight Road 20 30 40Range Bins 50 60 20 30 40 50 Doppler Bins60 70 80dB−0 −5 −10 −15 −20 −25 ch17.indd   26 12/17/07   6:49:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 
 15.Wei!.'I'.A.:Comparison ofCFA'sforPulsed-Radar Transmitters. Mierowa!w i..vol.16.pp.5154. 72.June.197J 16.1\nonymous: IntroductiontoPulsedCrossed-Field Amplifiers. 
 Willis and H. D. Griffiths, (eds.), Advances in Bistatic Radar , Raleigh NC: SciTech  Publishing Inc., 2007. 
 B, vol. 69. pp. 
 ,AVERTON!.&03 
 The combined  effect of such attenuations, and contributory causes, is  to set limits to maximum communication ranges at  various transmission frequencies. At the lower fre-  quency limit, for example, it has for many years been  realized that even for night transmission a frequency of  4000 kcs is the lowest which can successfully be used.  Limits at the other end of the scale have not until com-  paratively recent years been of great interest, for trans-  mission below about 5 metres was not a practical com-  mercial proposition until the last decade or so. 
 DET. DET. AMPL. 
 HORIZON /4(  RADAR IS TO PROVIDE A CAPABILITY FOR EARLY WARNING DETEC 
       $AY 6n    
 0., and M. Morgan: Isolation of Separate Transmitter and Receiver Aerials for Continuous  Wave Radars, Marconi Review, vol. 26, pp. 
 For array antennas the following seem to apply:  1. The larger the number of elements (MN) it1 the array, the stnaller will be the sptrriolis  radiation for a given error tolerance and a given design sidelobe level. In other words, lower  sidelobes are more likely to be achieved with larger antennas. 
 The signal generator power is then applied to the receiver input and adjusted until  the signal-plus-noise power is equal to twice the receiver noise power read with the matched  resistance. The input signal under this condition is sometimes said to be the minimum discern­ ible signal. It is also proportional to. 
 Large antennas are required to achieve narrow beam widths, the natural ambient noise level is high, the available bandwidths are narrow, and this portion of the electromagnetic spectrum is widely used and restrictively narrow. In addition, the long wavelength means that many targets of interest might be in the Rayleigh region, where the dimensions of the target are small compared with the wavelength; hence, the radar cross section of targets small in size compared with the (HF) wavelength might be lower than the cross section at microwave frequencies. The British used this frequency band, even though it had disadvantages, be- cause it was the highest frequency at which reliable, readily available high-power components were then available. 
 Marshall, “The distribution with size of aggregate snowflakes,”   J. Meteorol ., vol. 15, pp. 
 25.2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 25.2 RECEIVE CHANNEL PROCESSING Major advances in analog-to-digital converter and digital component technology have  transformed the receiver front ends of radar systems, providing higher performance at  lower cost. This section will describe how these new technologies are being applied to  radar systems and the benefits they bring to system performance. Signal Sampling Basics. 
   
 Tracking through Eclipse. Because of the range ambiguities in medium and high PRF, the radar must cope with the loss of target each time that it passes through eclipse. Automatic tracking systems might recycle to the search mode if eclipse is not recognized and preventive measures taken. 
 SIN  ,/ SAMPLE PAIRS CYCLE REPEATEDLY THROUGH       n   n     AND     .EXT  SUPPOSE THE )& SIGNAL IS A  -(Z SINUSOID OF ARBITRARY PHASE AS IN LINE B   4HE $$#S MIXER OUTPUTS ) AND 1  THE PRODUCTS OF THE LINE B  )& SIGNAL WITH THE TWO  .   2!$!2 $)')4!, 3)'.!, 02/#%33).'   Óx°££ LINE A  ,/ SIGNALS  ARE THEN AS IN LINE C  "ECAUSE OUR HYPOTHETICAL )& SIGNAL ON  LINE B  WAS EXACTLY AT ONE QUARTER OF THE SAMPLE RATE  BOTH ) AND 1 ARE CONSTANTS  THE SINE AND COSINE OF THE )& SIGNALS PHASE ANGLE &IGURE  SHOWS THE SAME  -(Z )& TONE  BUT SAMPLED AT  -(Z AND  -(Z   WHICH ARE ODD INTEGER SUBMULTIPLES  AND   OF THE ORIGINAL SAMPLE RATE OF ¾ THE )& CENTER FREQUENCY   -(Z .OTE THAT ODD SAMPLES STILL CYCLE BE TWEEN ) AND )  AND THE  EVEN SAMPLES SWITCH BETWEEN 1 AND 1 /DD INTEGER SUBMULTIPLES OF ¾ THE )& CENTER FREQUENCY CAN  THEREFORE  BE VIABLE ALTERNATIVE SAMPLE RATES ! .YQUIST BOUND APPLIES AND REQUIRES THE TWO 
 Lenses (Fig. 6.3g) are not as popular as they once were, largely because phased arrays are providing many functions that lenses once fulfilled. Primarily they avoid blockage, which can become prohibitive in reflectors with extensive feed systems. 
 Similarly, an electron leaving later than the reference electron catches upbyspending less time inthe retarding field asare- sult ofitslowered velocity. The neteffect isthat theelectrons gather inabunch. IAtcertain reflector voltages thebunch willpass through thecavity grids insuch aphase that+40 g Ei=EaCathdde-anode voltage=290 v ~+20wavelength= 10.7cm =.: ;.$o := S’-20L .-40 Ii;=-30 -40 -50 -60Reflectorvoltage F1~.11.23.—Reflector characteristics ofthe 707A. 
 PLIES THE RECTANGULAR INPUT  THE RESULT IS TYPICALLY A FUNCTION WITH BROADER MAINLOBE AND LOWER SIDELOBES THAN THE  SINC   SEE 3ECTION  OF 3ULLIVAN  ! TYPICAL  WEIGHTING FUNCTION USED IN 3!2 PROCESSING IS 4AYLOR WEIGHTING  WITH THE FIRST SIDELOBE CONSTRAINED TO BE n D" BELOW THE PEAK AND hNBAR    v SEE 3ECTION  $ OF #ARRARA ET AL    WHICH PRODUCES A WIDENED MAIN BEAM OF  
 When the swath is significantly less than the unambig­ uous range, a buffer can be inserted after the A/D convertors to read the data out at a slower  speed so as to process at a lower data rate than if the entire unambiguous range had to be  imaged. Digital processing also allows the use of a nonlinear sweep to convert slant range to  ground distance so as to make distances correct on the image.  Doppler-frequency model. 
 4. Experiment Results and Analysis The Gotcha public release dataset was used to illustrate our method. Gotcha data consists of SAR phase history data collected at X-band with a 640 MHz bandwidth with full 360-degree azimuth coverage and full polarization [ 26]. 
 69Rckcfi.G.,andG.W.Farnell: AHomogeneous Dielectric SphereasaMicrowave Lens,Call.J. Phys..vol.34.Pl'.790803.August. 1956. 
 64, pp. 239-272, February,  1976.  15 l. 
 125-132, 1975.  13. Bair, G. 
 Targets that donotshow such effects insome degree areexceedingly rare. These rule-of-thumb criteria areinadequate forthe consistent judg- ment ofradar performance, ashas been shown bysurveys ofradar performance made onradar equipment inthe field during the war. Unfortunately during most ofthe war adequate test equipment was commonly lacklng; when itwas present, itwas often incharge ofinade- quately trained maintenance personnel who didnot appreciate the need forusing itregularly. 
 Melvin, and L. Timmoneri, “Multichannel array processing in  radar: State of the art, hot topics and way ahead,” Proc. Sensor Array and Multichannel Signal  Processing IEEE Workshop  (invited paper), Sitges, Spain, July 18–21, 2004, pp. 
 f Table13.1WorldMeteorological' Organization sea state Waveheight Seaslale Feet Meters Descriptive term 0 0() Calm,glassy 1 ()! 0-0.1 Calm,rippled 2 ~"I!n.IO.5 Smooth, wavelets .I 24 0.6-1.2 Slight 4 48 1.2-2.4 Moderate 5 8132.4-4.0 Rough 6 1320 4.0-6.0 Veryrough 7 20306.09.0 High R 30-45 9.0-14 Veryhigh 9 over45over14Phenomenal. 476 INTRODUCTION TO RADAR SYSTEMS  Variation with frequency and polarization. From Fig. 
 Atargetatlongrangehaslowangular ratesand alowsignal-to-noise ratio.Anarrowtracking bandwidth isindicated insuchacasetoincrease sensitivity andyetfollowthetargetwithminimum lag.Atshortrange,however, theangular ratesarelikelytobelargesothatawidetracking bandwidth isneededinordertofollowthe targetproperly. Thelossinsensitivity duetothegreaterbandwidth.is offsetbythegreater targetsignalattheshorterranges.Thebandwidth shouldbenowiderthannecessary inorder tokeeptheangleerrorsduetotargetscintillation, orglint,frombecoming excessive. The tracking handwidth insomesystems mightbemadevariable orevenadaptive toconform automatically tothetargetconditions. 
 30  False alarm probability, 24  False alarm time. 24-26, 32  Far field. antenna. 
 The inclusion  of a safety factor in design is not always appreciated, especially in competitive procurements,  but it is a standard procedure in many other engineering disciplines. In the few cases where this  luxury was permitted. fine radars were obtained since they accomplished what was needed  even under degraded conditions. 
 The l-cm art was inavery early state, and equipment was still cumbersome and ofpoor performance. For this reason, 3.2cmwas chosen. This was afortunate choice; for. 
 Close Control with SCR-584—Figure 710 shows, attached to theFDP’s, SCR-584 radar sets. This equipment, designed foraccurate tracking ofasingle aircraft atatime, inorder topermit antiaircraft fire control, can also beused toprovide toaground controller theinformation necessary forhighly precise control oftheaircraft being tracked. Itwas soused bytheTAC’S inEurope. 
        
 S. Zrnic and R. J. 
 TRIBUTION OF INDUCED FIELDS ON TARGET SURFACES 4HE MOST USEFUL APPROACH TO A SOLUTION IS KNOWN AS THE  METHOD OF MOMENTS   IN WHICH THE INTEGRAL EQUATIONS ARE REDUCED TO  A SYSTEM OF LINEAR HOMOGENEOUS EQUATIONS 4HE ATTRACTION OF THIS METHOD IS THAT THE SURFACE PROFILE OF THE BODY IS UNRESTRICTED  ALLOWING THE COMPUTATION OF THE SCATTERING #HAPTER . £{°Ó  2!$!2 (!.$"//+  FROM TRULY TACTICAL OBJECTS !NOTHER IS THAT ORDINARY METHODS OF SOLUTION MATRIX INVER 
 The theory for volume scatter has led to many papers and con - tinues to evolve. For a review of some of the approaches, the reader should consult  Fung’s summary69 and papers by Kong, Lang, Fung, and Tsang. These models have  been used reasonably successfully to describe scatter from vegetation,70 snow,71 and  sea ice.72 Models of straight vegetation such as wheat in terms of cylinders have had  some success.2,73 Corner-reflector effects have been used to describe strong returns  from buildings at non-normal incidence angles.74,75 Other specialized models have  been used for particular purposes. 
 Kan, Y.Z.; Zhu, Y.F.; Tang, L.; Fu, Q.; Pei, H.C. FGG-NUFFT-based method for near-ﬁeld 3-D imaging using millimeter waves. Sensors 2016 ,16, 1–15. 
 TIME FOR SINE 
 ING AND ASSOCIATED DIFFUSION TO LOWER LATITUDES  TOGETHER WITH A VARIETY OF MAGNETIC FIELD PERTURBATIONS (& PROPAGATION IS OFTEN SEVERELY DISRUPTED -ODELS AND 4HEIR 5SES  +NOWLEDGE OF THE CONDITIONS TO BE EXPECTED FOR A PAR 
 M. Thomson, “The astromesh deployable reflector,” IEEE Symp. Antennas and Propag .,  pp. 
 Range  control is then set so that the electron beam is travelling  at a speed bearing relation to the required range of the  outfit. The Cal is switched on, injecting on to the Y  plates, instead of a radio signal, a locally generated series  of direct-current pulses separated by a predetermined  time interval, such as ss second, which corresponds to  increments of range equal to ten miles. These ‘ro-mile  pips’ we spread out by means of another voltage control  until the required time-base length is available. 
 Other binary coding methods that have been considered for pulse compression include :3 5  (I) compound Barker codes for obtaining longer codes from the Barker series by coding seg­ ments of one Barker code with another Barker code (a length 13 Barker code compounded  within another length 13 code gives a pulse-compression ratio of 169 and a pe¥ sidelohe of  -22.3 dB); (2) code sequencing 011 successive PRF periods, in which a different code is used for  each transmission to produce random sidelobes which when N pulses are added to produce a  J"N improvement in mainlobe-to-sidelobe amplitude ratio, where N is the number of se­ quences employed; and (3) complementary codes in which a pair of equal-length codes have the  property that the time side lobes of one code are the negative of the other so that if two codes of  a complementary pair are alternated on successive transmissions, the algebraic sum of the two  autocorrelation functions is zero except for the cental peak;36•37  A pulse burst is a waveform in which a series of pulses are transmitted as a group before  any of the echo signals are received. It is used to obtain simultaneous range and doppler­ velocity resolution when the minimum range is relatively Ion~; as for radars whose targets are  extraterrestrial, such as satellites and ballistic missiles. Pulse compression might be applied to  each of the individual pulses of the burst for better range resolution, and amplitude weighting  of the pulse burst might be used to lower the doppler sidelobe level to improve the detection of  small doppler-shifted target echoes close in frequency to large clutter echoes. 
 It will be recalled that the sawtooth frequency-modulated waveform of the  FM-CW radar was capable of determining the range as long as there was no doppler frequency  shift. By using a triangular waveform instead of the sawtooth waveform it was possible to  measure both the range and the doppler frequency. The same technique can be used with the  frequency-modulated pulse radar. 
 When vertical soundings are made with an ionosonde that uses a linearly polarized antenna, the ionosphere will be birefractive and provide two traces that are called ordinary and extraordinary. With right-hand and left-hand circularly polarized antennas the two responses can be separated. Figure 24.9« and b gives an example in the mid-Atlantic off the east coast from the data file. 
 AP-21, pp. 579–581, July 1973. 61. 
 Summers, J. E., and D. J. 
 CALLY REMOVING VEGETATION AND SMOOTHING OUT WINDBLOWN RIDGES IN UNSTABLE SOIL 4HE ANGLE OF INCIDENCE AND THE DIELECTRIC PROPERTIES OF ASPHALT AND NATURAL SOIL ARE  SUCH THAT THE PHASE OF THE VOLTAGE REFLECTION COEFFICIENT IS WITHIN A FEW DEGREES OF  4HIS BEING THE CASE  ONE CAN USUALLY CHOOSE A COMBINATION OF TARGET AND ANTENNA  HEIGHTS SUCH THAT THE WAVE REFLECTED BY THE GROUND ARRIVES AT THE TARGET IN PHASE WITH  THE WAVE PROPAGATED DIRECTLY FROM THE ANTENNAS 4HE RESULT IS THE FOLLOWING RULE FOR SELECTING THE ANTENNA AND TARGET HEIGHTS   HH 2 AT L    WHERE HA AND HT ARE THE ANTENNA AND TARGETS HEIGHTS  RESPECTIVELY  AND  2 IS THE RANGE TO  THE TARGET "ECAUSE MOST TEST RANGES HAVE TURNTABLES OR TARGET PYLONS INSTALLED AT A FEW FIXED  LOCATIONS RELATIVE TO A PERMANENT RADAR COMPLEX  THE RANGE  2 IS USUALLY RESTRICTED TO A  FEW PRESET VALUES 4HE TARGET IS INSTALLED AT A HEIGHT  HT HIGH ENOUGH TO MINIMIZE SPURI 
 5.1can doallthat isrequired. Practically, however, two important modifications must bemade. First, steps must betaken tokeep asmuch transmitter power as possible out ofthe rectifier. 
 MAP 
 Hühnerfuss, W. Alpers, A. Cross, W. 
 Inthefrequency-modulated CWradar(abbreviated FM-CW), thetransmitter frequency ischanged asafunction oftimeinaknownmanner. Assume thatthetransmitter frequency increases linearlywithtime,asshownbythesolidline inFig.3.lOa.Ifthereisareflecting objectatadistanceR,anechosignalwillreturnafteratime T=2R/c.Thedashedlineinthefigurerepresents theechosignal.Iftheechosignalis heterodyned withaportionofthetransmitter signalinanonlinear element suchasadiode,a beatnotefbwillbeproduced. Ifthereisnodoppler frequency shift,thebeatnote(difference frequency) isameasure ofthetarget'srangeandfb=j,.,wheref,. 
 FIG. 10.14 Time-frequency-coded waveform. TABLE 10.6 N Pulses Contiguous in Time and Frequency Shaping of the high-resolution central spike area as well as the gross structure of the ambiguity surface can be accomplished by variations of the basic waveform parameters such as amplitude weighting of the pulse train, staggeringWaveform duration, T Waveform bandwidth, B Time-bandwidth product, TB Compressed pulse width, l/BNT MT N2 T/N = TIN2 . 
 Geophys.  Res., vol. A109, pp. 
 When the term trcickirrg radar is used in this book, it generally refers to the continuous  tracker, unlcss otherwise specified.  The alltenria pattern commonly employed with tracking radars is the symmetrical pencil beart1  iri which the, elevation and azimuth beamwidths are approximately equal. However, a simple  pencil-beam antenna is not suitable for tracking radars unless means are provided for deter-  mining the magnitude and direction of the target's angular position with respect to some  reference direction, usually the alris of the antenna. 
 C. Schleher, Electronic Warfare in the Information Age , Norwood, MA: Artech House, Inc., 1999.  5. 
 The exact expression for the RCS of the dielectric cylinder is more compli- cated than for the conducting cylinder, but it accounts for the fact that energy penetrates the interior of the body. Unless the cylinder material is a perfect in- . ka FIG. 
 ING POINT TARGET  BUT DO NOT CLAIM TO HAVE PRODUCED A SIMULATED IMAGE OF AN EXTENDED MOVING TARGET  SUCH AS A VEHICLE p  0ARAGRAPH COURTESY OF $R -ARSHALL 'REENSPAN  .ORTHROP 
  %3! n     +U9ES  '&/ 53! n     +U9ES  *ASON 
 627. 37. D. 
 These are (1) the maximum amount of power the receiver  input circuitry can withstand before it is physically damaged or its sensitivity reduced  (burnout) and (2) the amount of transmitter noise due to hum, microphonics, stray pick-up,  and instability which enters the receiver from the transmitter. The additional noise introduced  by the transmitter reduces the receiver sensitivity. Except where the CW radar operates with  relatively low transmitter power and insensitive receivers, additional isolation is usually  required hctwceri tlie transmitter and tlic receiver if tile sensitivity is not to be degraded either  by bur noirt or by excessive noise. 
 1.4RADAR FREQUENCIES Conventional radarsgenerally havebeenoperated atfrequencies extending fromabout 220MHzto35GHz,aspreadofmorethansevenoctaves.Thesearenotnecessarily the limits, sinceradarscanbe,andhavebeen,operated atfrequencies outsideeitherendofthisrange. Skywave HFover-the-horizon (OTH)radarmightbeatfrequencies aslowas4or5MHz,and groundwave HFradarsaslowas2MHz.Attheotherendofthespectrum, millimeter radars haveoperated at94GHz.Laserradarsoperateatevenhigherfrequencies. Theplaceofradarfrequencies intheelectromagnetic spectrum isshowninFig.1.4.Some ofthenomenclature employed todesignate thevariousfrequency regionsisalsoshown. 
 Steinmetz: Amplitude and Phase-sensing Monopulse System Parameters, pts I  and 11, Aficrowar!~ 3.. vol. 2, pp. 
 18ofthieeeriea.. SEC.13.6] AMPLIFIERS 493 whence thegain oftheentire device is (1) IfPislarge compared toI/GO, variations inGOwill have little effect onG. Care must betaken, inusing large values ofGOand ~,that phase shifts insome ofthefrequency components donotresult inpositive feed- back and hence distortion oreven oscillation. 
 DAY SUBCYCLE   DESIGNED TO PROVIDE DENSE INTERLOCKING COVERAGE OVER THE POLAR REGIONS )TS AIM IS TO STUDY POSSIBLE CLIMATE VARIABILITY AND TRENDS BY DETERMINING THE VARIATIONS IN THICKNESS OF THE %ARTHS CONTINENTAL ICE SHEETS AND MARINE SEA ICE COVER #RYO3AT IS DESCRIBED IN MORE DETAIL IN A SUBSEQUENT SECTION !LTI+A !LTI+A DIFFERS FROM OTHER OCEAN 
 18.10 Approximately ideal feed-aper- ture E-field distribution for sum and differ- ence signals.FRONT ELEVATIONDIFFERENCE SUM AZIMUTHDIFFERENCE . FIG. 18.11 Twelve-horn feed. 
 Leith, and G. O. Hall, “A high-resolution radar combat-   surveillance system,” IRE Transactions on Military Electronics , vol. 
 Oneoftherequirements ofthedoppler-frequency amplifier inthesimple CWradar(Fig.3.2)ortheIFamplifier ofthesideband superheterodyne (Fig.3.4)isthatitbe wideenoughtopasstheexpected rangeofdoppler frequencies. Inmostcasesofpractical interesttheexpected rangeofdoppler frequencies willbemuchwiderthanthefrequency spectrum occupied bythesignalenergy.Consequently, theuseofawideband amplifier cover­ ingtheexpected doppler rangewillresultinanincrease innoiseandalowering ofthereceiver s;ensitivity. Ifthefrequency ofthedoppler-shifted echosignalwereknownbeforehand, a narrowband filter-one justwideenoughtoreducetheexcessnoisewithout eliminating a significant amountofsignalenergy-might beused.Ifthewaveform oftheechosignalwere known,aswellasitscarrierfrequency, thematched filtercouldbespecified asoutlined in Sec.10.2. 
 Englewood Cliffs, N.J., 1964. 150 INTRODUCTION TO RADAR SYSTEMS  47. Nathanson, F. 
 5) (H.M.  Stationery Office, 1927).  WATSON-WaATT, SiR ROBERT, Herp, J. 
 K. Parker, “Vacuum electronics for the 21st  century,” IEEE Microwave Magazine , pp. 61–72, September 2001. 
 26. Medhurst, R. G.: Rainfall Attenuation of Centimeter Waves: Comparison of Theory and Measurement, IEEE Trans., vol. 
 SWATHS BE KNITTED TOGETHER SUCH THAT THE CROSSOVERS BETWEEN ANTENNA PATTERNS ARE NOT EVIDENT 2!$!23!4 
 Near ﬁeld scattering measurement based on ISAR imaging technique. In Proceedings of the IEEE International Symposium on Antennas, Propagation & EM Theory, Xi’an, China, 22–26 October 2012; pp. 725–728. 
 Thedesignoftheradarreceiverwilldependnotonlyonthetype ofwaveform tobedetected, butonthenatureofthenoise,interference, andclutterechoeswith whichthedesiredechosignalsmustcompete. Inthischapter, thereceiverdesignisconsidered mainlyasaproblem ofextracting desiredsignalsfromnoise.Chapter 13considers theproblem ofradardesignwhenthedesiredsignalsmustcompete withclutter.Thecurrentchapteralso includes briefdiscussions ofradardisplays andduplexers. Noisecanenterthereceiverviatheantenna terminals alongwiththedesiredsignals,orit mightbegenerated withinthereceiver itself.Atthemicrowave frequencies usuallyusedfor radar,theexternal noisewhichentersviatheantenna isgenerally quitelowsothatthereceiver sensitivity isusuallysetbytheinternalnoisegenerated withinthereceiver. 
 745–808, July 1960.  2. C. 
 Croney, J.. and J. R. 
 34. Bauer, J. R., W. 
 VELOCITY CORRELATION PERFORMED ON TWO DETECTIONS ACROSS TWO LOOKS !MBIGUOUS  DETECTIONS ARE UNFOLDED OUT TO A MAXIMUM POSITIVE AND NEGATIVE VELOCITY. {°Î{  2!$!2 (!.$"//+  TIMES THE 02&  VELOCITY FIRST BLIND SPEED  TO EACH MEASURED AMBIGUOUS RADIAL VELOCITY  AS FOLLOWS   6F& .*+2 UNFOLDCENTROID &&4 
 SPHERIC FREQUENCY MODULATION v )%%% 4RANS !NT 0ROP  VOL !0 
 ETITION FREQUENCY (02&  MODES VELOCITY SEARCH 63  PRIMARILY DEDICATED TO LONGEST RANGE DETECTION AND RANGE WHILE SEARCH  273   WHICH USES SOME FORM OF &- RANGING  TO ESTIMATE TARGET RANGE 4HERE IS A MEDIUM 02& -02&  MODE  WHICH PROVIDES ALL ASPECT VELOCITY 
 OE-2, pp. 12–19, 1977. 54. 
 N.: A Fast Electronically Scanned Radar Receiving System, J. Brit. Inst. 
 Similarly, the fact that theindicators must beblanked outforthefirst 30~sec isofno importance since targets atsuch close range are practically never of interest. Several r-f equipments, including the three described inearlier sections, were tried experimentally inthis application. Alloperated with reasonable satisfaction, maximum range being limited inevery case only bythe line ofsight. 
 Toasufficient approximation, LL=R&t..~,where 1/10isthefraction offinal current built upinthe rise time t,. Ift,=0.1X10-’ see, R.=1000 ohms, and I/10 =0.9, L1must beless than 100ph. Satisfactory high-power (100-kw to5000-kw) pulse transformers have been designed which pass good wave shapes down totO=10–7 sec and uptoto=ltiK see, but itisquite difficult todesign apulse trans- former topass awide range ofpulse lengths. 
 Price, A.: "Instruments of Darkness," Macdonald and Janes, London, 1977.  14. Lobanov, M. 
 68.Bates,C.N.:NewAdvances inDoppler Radar,Countermeasures, vol.2,pp.34-37,April,1976. 69.Acker,A.E.:Eliminating Transmitted ClutterinDoppler RadarSystems, Microwave J.,vol.1l:l, pp.47-50,November, 1975. 70.Gupta,P.D.:ExactDerivation oftheDoppler ShiftFormula foraRadarEchoWithout Using Transformation Equations, Am.J.Phys.,vol.45,pp.674-675, July,1977. 
 STAGE LIMITER HAVING A PERFECTLY SYMMETRICAL CLIPPING AT VOLTAGES o% &OR A SINUSOIDAL INPUT  THE OUTPUT SIGNAL AT THE THRESHOLD OF LIMITING IS  V   %SINV T    .   2!$!2 2%#%)6%23   È°Î£ AND WHEN THE LIMITER IS FULLY SATURATED AND THE OUTPUT WAVEFORM IS RECTANGULAR  IT IS  GIVEN BY THE &OURIER SERIES   `   c £ V% NNTO N PSIN       V    WHICH IS AN INCREASE OF  LOG O       D" IN THE POWER OF THE FUNDAMENTAL )N PRACTICE  THE AMPLITUDE PERFORMANCE IS ALSO DEGRADED BY CAPACITIVE COUPLING  BETWEEN INPUT AND OUTPUT OF EACH LIMITING STAGE  CHARGE STORAGE IN TRANSISTORS AND  DIODES  AND  2# TIME CONSTANTS THAT PERMIT CHANGES IN BIAS WITH SIGNAL LEVEL &OR THESE  REASONS  TWO OR MORE LIMITER STAGES MAY BE CASCADED WHEN GOOD AMPLITUDE UNIFORMITY IS REQUIRED OVER A WIDE DYNAMIC RANGE 0HASE 5NIFORMITY  4HE CHANGE OF INSERTION PHASE OF THE LIMITER WITH AMPLITUDE IS  LESS OF A CONCERN FOR MODERN  RADAR SYSTEMS THAT OPERATE PRIMARI LY IN THE LINEAR OPERAT 
 Geophys. Res ., vol. 104, Issue C12, p. 
 Tube VCgenerates asawtooth sweep which moves thereflector voltage ofthelocal oscillator through arange determined bythesetting ofRte; thesweep isstopped at thecorrect voltage toreceive signals bythefiring ofthe control tube. The video amplifier consists ofalimiter-amplifier stage which drives a cathode follower operating into aline terminated with 75ohms. Limited signals of1.5volts amplitude appear across theline. 
 , 
 While the coordinates ofthis plan-position indicator (PPI) presentation thus lend themselves tocornparison withmaps, thecorrela- tion between the brightness pattern and the topographic features of the ground isamatter ofvarying difficulty, depending onthe nature oftheterrain, theexperience and skill oftheoperator, ancl theparticular 1The first signal toarrive isthereflection from tllrground directly I]elleath the aircraft; itiscalled the“altitu(ie signal” ljcctlll>(, itsr:illge isc,cltl:ll [otlle altitude of theaircraft. ZSee thechapter on“The .Mtitude Signal,)’ R.E.(’IJPP, “.iTheoretical and ExperiIllental Study ofRadt~r Grotlr){i Ret[lrll. ''RI,Ileport So.1024, lYW. 
 WAY BEAMWIDTH 4HE 02& IS  (Z 4HE ELLIPTIC FILTER DESIGNED FOR THESE PARAMETERS HAS AN IMPROVEMENT FACTOR OF  D" ("7 HITS PER ONE 
 This page has been reformatted by Knovel to provide easier navigation. xxx     Contents   GEOS-C SBR System Characteristics  ................  22.15  U.S.S.R. 
  IS #HINAS FIRST SYNTHETIC APERTURE RADAR MISSION 4HE SPACECRAFT MASS IS  KG   LAUNCHED INTO A SUN 
 2 4 .---~-~-~--,----r-----;r---,---.----r---i  0.22 - 0.20  S 0.18  V,  Cl)  > ·-g 0.16  Cl)  L  ~ 0.1 '1 ..  Cl)  O'  0  ~ 0.12 - >  0 .2' 0.10  V,  I e 0.08  L w  0.06 - 0.04 - 0.02 6q An ten no  6e crossover, dB  0.2 0.5  0.4 1.95  0.6 4.36  0.8 7. 7  O~~-~-~-~-~~-~--~-~~  0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0  0,/08 TRACKING RADAR 159  Figure 5.6 Plot of the relative angle­ error signal from the conical-scan radar  as a function of target angle (Or/88)  and squint angle (0.,108). 
 2. A small array is the best technique for determining the active element pattern. The  active element pattern, obtained by exciting one element and terminating its neigh - bors, is the best overall measure of array performance other than the full array itself. 
   2!$!2 2%#%)6%23   È°x )N ACTIVE ARRAY ANTENNAS  AND MANY CONVENTIONAL ANTENNAS  LOW 
 Initial LS Estimate For Equation ( 2), if the support set of sθiis known, we could simply compute the LS estimate on the support while setting all other values to zeros. The previous support can be estimated from the prior information. Suppose the estimated support is T, to compute and initial LS estimate (si,init)T=(ΦiT)†ri,(si,init)Tc=0. 
 HERTZ REFER 
 Barton, Modern Radar System Analysis , Norwood, MA: Artech House, 1988. 31. D. 
 Alrh~ugh the bistatic radar cannot readily imitate the hemispherical coverage of mono-  static radar, it is possible for the n1onostat.i~ radar to give fence coverage by using fixed, rather  than rotating. antennas. In order to compare the two on the basis of similar coverage, it will be  assumed tliat a rionscanning monostatic radar is operated at each end of a radar fence. 
 12. Watanabe, M., T. Tamana, and N. 
 TRANSFORMATION OF SIGNALS AND ITS APPLICATION TO DIRECTIONAL  SYSTEMS v 4HE 2ADIO AND %LECTRONIC %NGINEER  PP n  -ARCH . 
  PROVIDED THE FIRST GEODETIC AND GEOPHYSICAL RESULTS OF SIGNIFICANCE WITHIN THE .ATIONAL 'EODETIC 3ATELLITE 0ROGRAM  INCLUDING THE FIRST MAPS OF SEA 
 The amount, direction, and rate of orbit precession can be controlled by choice  of the inclination and the mean altitude of the orbit. Many satellite platforms use this  degree of freedom to generate a sun-synchronous orbit, which is one that maintains a  constant angle of its orbit plane relative to solar illumination over the entire year. The  European Space Agency’s Envisat spacecraft is a good example of a sun-synchronous  LEO, having ∼98.5° inclination† and 785 km altitude. 
 RANGE FIXED CLUTTER  AND SHORT 
 TheN-pulsenonrecufsive delay-line canceler allowsthedesignerNzerosforsynthesizing thefrequency response. Theresultisthatmanydelaylinesarerequired for.highly-shaped filter responses. Therearelimitstothe'n'umberofdelaylines(andpulses)thatcanheemplGyed, Therefore otherapproaches toMTlfilter implementation aresometimes desired. 
 J. B. Keller, “Diffraction by an aperture,” J. 
 For example, if the antenna azi- muth angle is at zero, any head-on target (VT cos i|ir > O) is clear of sidelobe clutter, whereas if the radar is in trail behind the target (i|/r = 180° and i|/0 = 0°), the target's radial velocity has to be greater than twice that of the radar to be- come clear of sidelobe clutter. The sidelobe clear and clutter regions can also be expressed in terms of the aspect angle with respect to the target,14 as shown in Fig. 17.4. 
 M. Shimada, M. Watanabe, T. 
 Forrest and J. G. Schoenenberger. 
 POWER TUBES )NSTEAD  OSCILLATIONS MAY BE PREVENTED BY THE USE OF DISCONTINUITIES CALLED SEVERS  WITH ONE SEVER FOR EVERY  TO  D" OF TUBE GAIN !T EACH SEVER  THE POWER TRAVELING IN THE REVERSE DIRECTION IS DISSIPATED IN THE SEVER LOADS WITHOUT SERIOUSLY AFFECTING THE POWER TRAVELING IN THE FORWARD DIRECTION 4HE SEVER LOADS MAY BE PLACED EXTERNAL TO THE TUBE TO REDUCE DIS 
 8.2bthe beacon replies ontheindicator ofthesame 3-cm radar set. The pictures were taken one immediately after theother onthesame flight. Byitsvery nature, theradar-beacon combination involves two send- receive links asdoes any two-way communication system. 
 TO 
 ING  NONLINEARITY AT ANY STAGE OF THE RECEIVER CHANNEL WILL CREATE SIMILAR PROBLEMS 3YSTEM CALIBRATION TECHNIQUES AND ADAPTIVE BEAMFORMING TECHNIQUES CAN COM 
   PP n  . £Ç°£-ÞÌ iÌVÊ«iÀÌÕÀiÊ,>`>À ,}iÀÊ-ÕÛ> )NSTITUTE FOR $EFENSE !NALYSES -OST OF THE DISCUSSION IN THIS (ANDBOOK CONCERNS  REAL APERTURE RADAR 2!2    WHERE THE ANTENNA IS A PHYSICAL OBJECT THAT FIRST EMITS  AND THEN COLLECTS  THE RADIA 
 13ofthisseries,. 644 MOVING-TARGET INDICATION [SEC. 16.7 Several remarks areinorder regarding the generality ofthe above experimental values. 
 This generates a sequence of length 2" - 2 and is not an  m-sequence.57) Table l l.3 lists the nui:nber of possible m-sequences obtainable from an  n-stage shift register.  Modulo 2 i------~  .------1 odder  2 3 4 5 6 7 Figure 11.20 Seven-bit shift-register for generating a pseudo- Output random linear recursive sequence of length 127. 430 INTRODUCTION TO RADAR SYSTEMS  Table 1.1.3 Number of m-sequences obtainable from an n-stage  shift register 1 6  Example  Length of Number of feedback  Number of maximal sequence maximal stage  stages, n 2n -l sequences connections  3 7 2 3, 2  4 15 2 4, 3  5 31 6 5, 3  6 63 6 6, 5  7 127 18 7, 6  8 255 16 8, 6, 5, 4  9 511 '48 . 
 Field T est The SPARX array operating principle has been tested with a reduced MIMO conﬁguration, composed of two transmitting module and just one receiving module, for a total of 64 virtual channels. The system has been deployed in an external environment where it was possible to recognize various reﬂecting targets at different ranges and azimuth angles. The purpose of this preliminary test was to achieve the correct MIMO imaging in order to detect and identify all the relevant targets. 
 Concerning azimuth resolution requirements, the azimuth sampling interval is Δθ≤λ 2D, wherein Drepresents maximum size of the target. (3) Distance from antenna and target This paper focuses on near-ﬁeld imaging, in principle, distance from the antenna to the target is represented as: R0<4D2 λ, wherein Drepresents maximum size of the target and λrepresents length of incident electromagnetic wave. In addition, scanning in vertical direction does not exist because the two antennas are located ﬁxedly, the beam center is ﬁxed and only the target rotates in InISAR. 
 24,  pp. 1024- 103 1, August, 1953.  14. 
 ING METHODS HAVE BEEN DEVELOPED AND REFINED ! '02 TRANSMITS A REGULAR SEQUENCE OF LOW 
 If the phase 4/ is constant with frequency, the scan angle 00 is frequency-dependent. Time-Delay Scanning. Phase scanning was seen to be frequency-sensitive. 
 BEAM 2&) THAT EXHIBITS CORRELA 
 N. C. Currie, and M. 
 (3)~ Thus ifjishalved, B=must double forafixed input voltage, all other terms being constant inany given case. Since losses intheiron are afunction ofB-,doubling B~.. produces animmense increase in magnetizing current and incore loss. 
 RANGE IS OBTAINED BY TRANS 
 I. Skolnik (ed.), New York:  McGraw-Hill, 1970, pp. 17–19. 
 Ward29 © IEEE 1972 ) ch07.indd   17 12/17/07   2:13:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 2J 25. 1973. pp. 
 ,/"  $IPLEX "ENEFITS  $IPLEX OPERATION CONSISTS OF TWO RECEIVERS THAT SIMULTANEOUSLY  PROCESS RETURNS FROM TRANSMISSIONS ON DIFFERENT FREQUENCIES 4RANSMISSIONS ARE USU 
 I. Skolnik (ed.), McGraw­ Hill Book Co., New York, 1970.  58. 
 ING ANTENNA AS A CONSEQUENCE OF THE TIME 
 GENERATION RADARS DUE TO THE RELATIVELY RECENT MATURATION OF ENABLING %3! TECHNOLOGY 3PHERICAL 2EFLECTORS n 4HE SPHERICAL REFLECTOR IS SOMETIMES USED FOR APPLI 
 TO 
 H.: "Man and Radar Displays," The Macmillan Company, New York, 1962.  52. Swerling, P.: The" Double Threshold" Method of Detection, Rand Corp. 
 MODULATION OCCURS AS A RESULT OF THIRD ORDER  INTERMODULATION  WHEREBY THE AMPLITUDE MODULATION !-  OF ONE SIGNAL  TYPICALLY AN UNWANTED INTERFERENCE SIGNAL IN THE OPERATING 2& BAND BUT USUALLY OUTSIDE THE TUNED SIGNAL BANDWIDTH  IS TRANSFERRED ONTO THE DESIRED SIGNAL.   2!$!2 2%#%)6%23   È°Ç 4HE RESULTANT PERCENT !- MODULATION  D  ON THE DESIRED SIGNAL IS GIVEN BY   DU0 005 5   )0    WHERE  U    PERCENT !- MODULATION OF THE UNWANTED SIGNAL   05   POWER OF UNWANTED SIGNAL   0)0   THIRD ORDER INTERCEPT POINT #ROSS MODULATION CAN RESULT IN THE MODULATION OF CLUTTER AND TARGET RETURNS DUE TO  LARGE AMPLITUDE MODULATED OUT 
   #OSINE  
 B. D .. J. 
 BEAM AND SIDELOBE JAMMING  BY PROCESSING THE DATA  RECEIVED BY A SET OF LOW AND HIGH GAIN BEAMS 4HE SET OF RECEIVED RADAR ECHOES   6 x  B3P4  E4    D  DEPENDS ON THE ANGULAR COORDINATES OF THE TARGET   P4  E4   THE COMPLEX  TARGET AMPLITUDE  B  AND WHITE GAUSSIAN ZERO MEAN NOISE PLUS JAMMING DISTURBANCE  D  3 IS A VECTOR CONTAINING THE VALUES OF THE PATTERNS OF HIGH AND LOW GAIN ANTENNAS IN A CERTAIN DIRECTION P   E  4HE DATA  6 ARE CHARACTERIZED BY A GAUSSIAN PROBABILITY DENSITY  FUNCTION CONDITIONED TO THE TARGET UNKNOWN PARAMETERS  IE   P V6B  P4  E4   4HE -,  ESTIMATION OF THE TARGETS UNKNOWN PARAMETERS IS OBTAINED AS FOLLOWS  } } }  ARGMIN        BB B44 B( D QF Q FQF 
 76. Dyer. F. 
 IIIB and later versions. Range on ASV Mk. III was calibrated in statute miles but on ASV Mk. 
 Raw data is repeatedly processed for speciﬁc parameters of different moving ship, and the computation cost greatly increases [ 6]. The processing data are sub-images selected from ordinary SAR images, not raw data, and the sub-images are converted into the raw echo data domain by an inversion algorithm. The sub-images in the raw echo data domain are refocused with the ISAR technique, and the moving ships can then be well-focused. 
 19. S. A. 
 2 1 --23. 1975, pp. 3 12- 3 17. 
 NATED  THIS GEOMETRY IS USEFUL FOR VERY LOW SIDELOBE APPLICATIONS  !S DESCRIBED EARLIER  THE APERTURE EFFICIENCY OF SINGLE REFLECTOR SYSTEMS IS MAXI 
 PROPAGATING WAVE AND RADIATION PROCESSES  WHEREAS THE %ARTHS MAGNETOSPHERE  THE REGION BEYOND THE IONOSPHERE WHERE THE SOLAR WIND INTERACTS WITH THE %ARTHS MAGNETIC FIELD  IS THE SOURCE OR CONDUIT FOR CORRESPONDING PERTURBATIONS FROM ABOVE 4HE IONOSPHERIC RESPONSE TO ALL THESE EXTERNAL FORCES IS GOVERNED NOT ONLY BY INERTIAL EFFECTS BUT ALSO BY CHEMICAL REACTIONS AND BY THE EMBEDDED TIME 
 The A1 radar operated at a  frequency of 200 MHz. During the development of the A1 radar it was noted that radar could  be used for the detection of ships from the air and also that the character of echoes from the  ground was dependent on the nature of the terrain. The former phenomenon was quickly  exploited for the detection and location of surface ships and submarines. 
   (& /6%2 
 THE RECEIVING SYSTEM—INDICATORS . 475 THE CATirOnE-RAY TUBE ...... 475 13.1 Electrical Properties ofCathode-ray Tubes. 
 Its effect is to cause a constant time delay. A time delay is necessary in the  specification of the filter for reasons of physical realizability since there can be no output from  the filter until the signal is applied. The frequency spectrum of the received signal may be  written as an amplitude spectrum I S(J) I and a phase spectrum exp [ -j<J,s(J)]. 
 R. C. Bi~rgener, and S. 
 SVD—Signal Processing SVD [ 20], in its economy formulation, is a standard algorithm able to decompose a given rectangular matrix into the product of three matrices, U,S, and V. Xis the data matrix of size M·N,U, and Vare orthonormal matrices, respectively named the le f t and right singular vectors matrices; each singular vector, either left or right, is represented by the generic column of the matrix UorV, respectively. In analytic form, The SVD decomposition can be written simply as: X=U·S·VH(1) where the superscript (·)Hrepresents the transpose and conjugate operator (Hilbert operator). 
 OF 
 Gini, “Calculation of blanking probability for the sidelobe blanking (SLB) for  two interference statistical models,” IEEE Signal Processing Letters , vol. 5, no. 4, pp. 
 cover search patterns 2. track moving targets 3. integrate (sum) several target returns to improve detection •T h e  p u l s e  t r a i n is a common waveform TIME  τPoTppeak instantaneous power (W) pulse width (sec) 1/ ,  pulse repetition frequency (PRF, Hz) interpulse period (sec)   number of pulseso pp pP fT T N τ= = = = =. 
 andaseparate emitting cathode isused.Thetwowordssaleandcathodearesometimes used interchangeably. Theslow-wave structure isdesignedsothatanRFsignalpropagates ata velocity ncarthatoftheelectron beam.Thispermitsanexchange ofenergyfromtheelectron heam(0(heRFficldtoproduce amplification.;\ d-celectricfieldisappliedbetween theanode (slow-wave structure) andthecathode. t\magnetic fieldisperpendicular totheplaneofthe paper.Theelectrons emitted fromthecathode. 
 INTRODUCTION TO  RADAR SYSTEMS  Second Edition  Merrill I. 
 QUENTLY  BISTATIC RADAR SURVEILLANCE CAN BE ENHANCED AND HOT CLUTTER CAN BE REDUCED IN THESE REGIONS L 6ALUES OF  R" ARE SIGNIFICANTLY LARGER NEAR THE FORWARD 
  TO     THE QUANTIZATION INTERVAL IS  .  
 :; '  1.6 APPLICATIONS OF RADAR  Radar has been employed on·the ground, in the air, on the sea, and in space. Ground-based  radar has been applied chiefly to· the detection, location, and tracking of aircraft or space  targets. Shipboard radar is· used a~ a ·navigation aid and safetf device to locate buoys, shore . 
 System A in Figure 9.15 a is a case of excessive peaking of about 8 dB. The effect of  the peaking is observed by applying a step error input to the servosystem. The peaking  of the low-pass characteristic results in an overshoot when the antenna axis moves to  align with the target. 
 For high-altitude operation, pressurization may beabsolutely necessary toprevent breakdown oftheline. The high-voltage cathode circuit ofthe magnetron isasimilar case. Pressurization assures dry conditions and sea-level pressure, and thus makes unnecessary thehuge insulators and large airclearances that standard engineering practice would otherwise prescribe. 
 Lloyd, G. W. Haydon, and D. 
 The rela- tive-bearing indication isbad for two reasons: (1)the entire display rotates and becomes confused ifthe course ofthe vehicle isaltered; (2) the natural random changes inthe heading ofthe vehicle cause acor- responding blurring ofthe display onthe persistent screen. The true- bearing indication isfree ofthese faults. Itisadata stabilization in regard toyawand changes ofheading. 
 Since 1972,  however, several major programs have changed the situation so that much information  is now available. Indeed, this information is so widespread that an adequate summary  of the literature is impossible. Hence, this section can only give highlights of the  results and major programs. 
 (1 1.39), and if x is identified withf, the theoretical  rms error can be obtained by analogy to the time-delay accuracy as given by Eq. (1 1.17), or  where y is the effective aperture width defined by  - w Y2 =  j IA(x)IZdx  -03  The theoretical angular error of an antenna with a rectangular amplitude distribution  across the aperture is  The effective aperture width is 27t times the square root of the normalized second moment of  I A(x)lZ about the mean value of x, taken to be at x = 0. The half-power beamwidth 8, of a  rectangular distribution is 0.88110, where 8, is in radians. 
 pp.18-21.April.1959. 6.1.Ciunderson. L.C.andJF.Kauffman: AHighTemperature Luneburg Lens,Proc.IEEE.vol.56. 
           
 The range tracker determines the time of arrival of the desired target echo and provides gate pulses which turn on portions of the radar receiver only during the brief period when the desired target echo is expected. The gated video is used to generate the dc voltage proportional to the magnitude of the 2 signal or IS I for the AGC of all three IF amplifier channels. The AGC maintains constant angle-tracking sensitivity (volts per degree error) even though the target echo signal varies over a large dynamic range by controlling gain or dividing by I2l. 
 Ifthefirst few microseconds ofthe radar cycle are not too important and the modulator isnotself-synchronous, itstrigger canbethethird pulse ofthe coded group. No range error will result, but the azimuth pulse will appear ontheindicators atthereceiving station atarange corresponding 1Thepulses can beseparated from thevideo signals byamplitude selection, orby time separation asinFig. 17.4.. 
 If the radar radiates one sense of circular polarized energy,  504INTRODUCTION TORADAR SYSTEMS 13.8DETECTION OFTARGETS INPRECIPITATION Thechiefeffectofweatheronradarperformance isthebackscatter, orclutter,fromprecipita­ tionwithintheradarresolution cell.Attenuation byprecipitation usuallyhaslittleeffecton thedetection oftargetsexceptatfrequencies aboveXband.Weather clutter,however, canbea seriousfactorinlimitingtheperformance ofmicrowave radarsevenatfrequencies aslowasL band.Goodradardesignmustincludemethods formaintaining performance inthepresence ofprecipitation. Themosteffective method forreducing theeffectsofprecipitation istooperateatalow frequency to'takeadvantage ofthesignificant decrease inbackscatter fromprecipitation with decrease infrequency. Thebackscatter crosssectionofaparticleintheRayleigh region.as shownbyEq.(13.17)variesasthefourthpowerofthefrequency. 
 This anode construction is placed  relatively much farther away from the cathode, and the  effective anode current is often only a few microamperes  ({millionths of an ampere). But the electrons are drawn  away from the cathode so fast that they pass almost  right through the anode construction, and travel on to  the far end of the tube, hitting the screen end of the  glass at a velocity usually in the nature of 15,000 miles  a second. The anode construction, as we shall see, is so-  arranged that the electrons are drawn off the cathode  and focused into a fine pencil. 
 N. Bringi, “Potential use of radar differential reflectivity measurements at orthogo - nal polarizations for measuring precipitation,” J. Appl. 
 2 7  In some high-range-resolution radars, however, the number of resolvable range cells available  from the radar might be greater than the number of resolution cells available on the PPI  screen. The result is a collapsing loss (Sec. 2.12). 
 The lens is usually less efficient than comparable reflector antennas because of loss when  propagating through the lens medium and the redectioris from the two lens surfaces. In a  zoned lens there will be additional, undesired scattering from the steps. Although it is danger-  ous to generalize, the additional losses from the sources in a stepped lens might be 1 or 2 dB.72  The lack of suitable solid or artificial dielectric materials has limited the de,yelopment of  lenses. 
 AMPLIFIER APPLICATIONS .   3/,)$ 
 Mode-skipping isdependent not only onthe characteristics ofthe magnetron but also onthe charac- teristics ofthepulser. Inpractice, ithasbeen necessary toconsider the magnetron and pulser asaunit. For given magnetic field and r-f loading, there isonly alimited range ofanode voltage over which the magnetron will build uposcillations inthe,desired mode. 
 Therefore the aperture distributiorl which generates the nth (sin ~)/$ composing pattern has  uniform amplitude and is proportional to the sampled value E,(rtA/d). The phase across the  aperture is sucil that tile individual cornposing patterns are displaced from one another by a  half a bearnwidtli (wliere tlic beamwidth is here defined as the distance between tile two nulls  wl~icli surround tlie mait1 bcarn). The phase is given by the exponential term of Eq. 
 (External noise is  discussed in Sec. 12.8.) The measure of receiver internal noise is the noise-figure (introduced  previously in Sec. 2.3). 
 384 INTRODUCTION TO RADAR SYSTEMS  where y = output voltage or detector and integrator  a amplitude of sine-wave signal divided by rms noise voltage  v = amplitude of IF voltage envelope divided by rms noise voltage  J0(x) = modified Bessel function of zero order  This equation specifies the form of the detector law which maximizes the likelihood ratio  for a fixed probability of false alarm. A suitable approximation lo Eq. (10.37) is91  y = In /0(av) ~ ~ + 4 -2 (10.38)  For large signal-to-noise ratios (a p 1 ), this is approximately  y ~ av ( 10.39)  Thus the linear detector is a good approximation to the optimum In I 0(ai1) detector law when  the signal-to-noise ratio is large. 
 SOIDALLY WITH ANTENNA AZIMUTH 4HUS  THE FIGURE SHOWS THE DOPPLER REGIONS IN WHICH THE TARGET BECOMES CLEAR OF SIDELOBE CLUTTER &OR EXAMPLE  IF THE ANTENNA MAIN 
 SENSING CIRCUITS MUST BE CAPTURED WITH A FALSE AMPLITUDE 
 Theapplied magnetic fieldisproportional tothecurrentinthedrive wirewhichcanbeconsidered asolenoid withoneturn.Whenasufficiently largecurrent is passedthrough thedrivewirethreading thecenterofthetoroid,themagnetization isdrivento saturation. Whenthecurrent isreduced tozero.thereexistsaremanent magnetization B~.lfa currentofopposite polarity ispassedthrough thedrivewire,theferriteissaturated withthe opposite polarity ofremanent magnetization. Thusatoroidal ferritemaytakeontwovaluesof magnetization, ±B~,obtained bypulsingthedrivewirewitheitherapositive ornegative currentpulse.Thedifference inthetwostatesofmagnetization produces thedifferential phase c 9o '" Saturation Remanent magnetization --"- t8, Appliedmagnetic field(H) -8, Figure8.11Hysteresis loop,orB-Hcurve.ofaferritetoroid.. 
 Óä°£Ê"ÛiÀÌ iÀâÊ,>`>À >iÃÊ °Êi>`ÀV .AVAL 2ESEARCH ,ABORATORY RETIRED  -ÌÕ>ÀÌÊ°Ê`iÀÃ !USTRALIAN $EFENCE 3CIENCE AND 4ECHNOLOGY /RGANISATION Óä°£Ê  /," 1 /"  "EYOND 
 and there is less of a problem caused by hysteresis in the ferrite. The toroid ferrite  phase shifter. although not perfect by any means, has been in the past a popular choice for  phased array application. 
 21. R. Turyn and J. 
 Assuming a suffi cient gap between  the frequencies of the pulses radiated exists , echo signals of a fluctuating target are statistically  decorrellated. Smoothing of fluctuation can be expressed in terms of signal -to-noise ratio gain,  maximum range gain or improved detectio n probability.     In Frequency Diversity Radar t he decreasing of fluctuation loss can effect uate either an  increased maximum range or an increased probability of detection. 
 I,  pp. 51 -66, 1960.  62. 
 ................................ ................................ ...................... 
 Thus all the response curves are normalized with respect to the average gain for the given canceler configuration. The inter- section at the ordinate represents the negative decibel value of /, the MTI im- provement factor for a point clutter target processed in a linear system. Because these curves show the signal-to-noise response for each output pulse from the MTI canceler, the inherent loss incurred in MTI processing due to the reduction of the effective number of independent pulses integrated18 is not appar- ent. 
 GRID REPRESENTATION OF THE AIRCRAFT DERIVED FROM A PLASTIC KIT MODEL 4HE 2#3 SHOWN IS FOR MONOSTATIC BACKSCATTER  GEOMETRY AND HORIZONTAL COPOLAR ((  POLARIZATION #ALCULATIONS ARE PRESENTED FOR FREQUENCIES OF     AND  -(Z !LTHOUGH THE FIDELITY OF SUCH 2#3 CALCULATIONS OF CONVENTIONAL PLATFORMS HAS BEEN  CONFIRMED ON MANY OCCASIONS  IT IS NOT CLEAR THAT STANDARD COMPUTATIONAL METHODS ARE APPLICABLE TO THE PROBLEM OF ESTIMATING THE 2#3 OF AIRCRAFT TARGETS THAT CANNOT BE MODELED AS SIMPLE PERFECT ELECTRICAL CONDUCTORS 0%#  OR TO SMALL hGO 
 TERM STABILITY REQUIREMENTS OF THE 34!,/ ARE GENERALLY CHARACTERIZED  BY DEVICE NOISE RELATIVE TO CARRIER D"C   SPECIFIED IN TERMS OF A PHASE NOISE SPECTRUM AND MEASURED IN THE FREQUENCY DOMAIN ,ONG 
 TION  INTERCEPTOR SUPPORT  AND INTERCEPT ASSESSMENT FUNCTIONS 4HESE FUNCTIONS INCLUDE SURVEILLANCE  4(!!$ MISSILE TRACK  IN 
 These additional lobes are due to reflector edge diffraction that adds  coherently and typically causes a relatively strong main backlobe behind the reflector.  Center-fed geometries, i.e., those with reflector edges equidistant from the feed, enable  coherent addition of the diffracted energy directly to the rear of the reflector. For these  geometries, the backlobe level is directly related to the edge illumination level.3 Surface Roughness Loss. 
 MODE FEED ILLUSTRATED IN  &IGURE  4HIS FEED USES THE SAME APPROACH AS DESCRIBED ABOVE BUT WITH THE ADDI 
 43. Pidgeon, V. W.: Bistatic Cross Section of the Sea, IEEE Trans., vol. 
 Radiation isfed into the parallel plates between these flanges byfour feed horns, each 2in.wide, with suitable chokes meeting the flanges. The four horns are mounted on four radial waveguides which arefedattheir intersection byafour-way r-fsector switch (Fig. 9.27). 
 ch11.indd   2 12/17/07   2:25:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 
 AVG  0' 2K 4& 6R  LSD PY    C O S00! 2K 4 & 6R 4X 
 Ineffect, alarge capacity gives poor regula- tion. Should thedesigner attempt torecover this loss bydecreasing the size ofthe recharging impedance, there will result anincreased curren I drain from the power supply through the switch tube during the pulse, thereby causing anincreased switch-tube drop. Careful balancing of these factors isrequired toachieve most efficient design. 
 Taylor: Doppler Radar Clutter, IEEE Trans., vol. ANE-Il, pp. 162-172, September 1964. 
 Magnetically focusedtubesutilizeeitheranelectromagnet orapermanent magnetaround. 354 INTRODUCTION TO RADAR SYSTEMS  the neck of the CRT to provide an axial magnetic field. Magnetic focus generally can provide  better resolution, but the spot tends to defocus at the edge of the tube. 
 The possibility ofadding tothe AN/APS-10 special units toperform special functions has, however, been retained. Atrigger pulse and video signals are available forany attachment, asare provisions foranadditional. azimuth-angle take-off and means forexternally reversing the azimuth scan motor. 
 Scarchilli, and V . Chandrasekar, “Calibration of radars using polarimetric tech - niques,” IEEE Trans. Geosci. 
 34$ 
 LeToan, “Active microwave signatures of soil and crops: significant results of three years of exper - iments,” Dig. Int. Geosci. 
 4, pp. 745–809, July 1960. 43. 
 M. I.: Millimeter and Submillimeter Wave Applications. "Submillimeter Waves." vol XX. 
         AAA AAA ;LNN   LN  =FF  
 However, we can discriminate between them by the degree of anisotropy, suggesting that different targets usually have different degrees of anisotropy. The scattering mechanism of dihedral A is very different from the trihedral. The scattering mechanism of dihedral B and trihedral are close but still discrepant. 
 The beamwidth can vary on the order of 4 to 1 over the entire scan range of  the dome ahtenna. Furthermore, the bean1 might not be as narrow on the horizon as might be  obtained with a convelitional antenna configuration of equivalent aperture. As with any array  Len5 w~lh F~xed  .--  / Planor feed array Figure 8.32 Dome antenna for achieving  Vortoble phase controls hemispherical coverage. 
 Clutter-CFAR  techniques that are "adaptive" do not have this limitation. (STC is also sometimes employed  in radar not bothered by clutter to make more uniform the target echo power with range.)  Another technique for reducing saturation is instantaneotts automatic gain control (IAGC)  based on negative feedback controlling the gain of the IF amplifier. The response time of the  IAGC is adjusted so that echo pulses from point targets pass with little attenuation, but longer  pulses such as those from extended clutter are attenuated. 
 Not unexpectedly, those coefficients are more compli- cated than the ^'s and Fs appearing in Eqs. (11.22) and (11.23), and (11.28) through (11.31).30'42 Mitzner expressed his result as the diffracted electric-field components paral- lel and perpendicular to the plane of scattering in terms of the components of the incident electric field parallel and perpendicular to the plane of incidence. As such, the diffraction coefficients may be expressed as three separate pairs repre- senting parallel-parallel, perpendicular-perpendicular, and parallel-perpendicular (or perpendicular-parallel) combinations. 
 SPACE-BASED REMOTE SENSING RADARS  18.536x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 18.5 SCATTEROMETERS Space-based remote sensing scatterometers measure the normalized backscatter with  sufficient precision and accuracy to deduce the value of one or more parameters of  geophysical significance. For example, the power reflected from the ocean back to a  radar is a function of surface roughness at the scale of the radar’s wavelength, which,  in turn, is a function of the local wind.119 Estimation of wind speed and direction over  the open ocean is the most common application for these instruments. A wind scat - terometer was adopted by EUMETSAT in the early 2000s as a required operational  capability, with operational accuracies of ±2 m/s in wind speed and ±20° in direction. 
 The justification for this definition is that the technology and design  philosophy of a multiple prf radar are more like that of an MTI than a pulse doppler.)  The pulse doppler radar is more likely to use range-gated doppler filter-banks than  delay-line cancelers. Also, a power amplifier such as a klystron is more likely to be used than a  power oscillator like the magnetron. A pulse doppler radar operates at a higher duty cycle  than does an MTI. 
 A single antenna beam from a doppler radar measures one component of aircraft velocity  relative to the direction of propagation. A minimum of three noncoplanar beams are needed to  determine the vector velocity, that is, the speed and direction of travel.  Doppler-navigation radar measures the vector velocity relative to the frame of reference  of the antenna assernbly. 
 2, pt. 1. pp. 
 Since the ionosphere varies wit11 time of  day, season, and solar activity, the optimum radar frequency will vary widely. Such radars  must therefore be capable of operating over a wide portion of the HF band, as much as three  octaves (4 to 32 MHz for e~ample).~' The ionosphere often consists of more than one rsfract-  1 ing region. The highest region, denoted F2, and the most important for HF propagation, is at  altitudes of from 230 to 400 km. 
 MFR is designed to detect low-observable anti-ship cruise missile (ASCM) threats and  support fire-control illumination requirements for multiple missiles. MFR combines  the functions provided by several separate radars aboard Navy combatant ships and  also supports new ship-design requirements for reduced radar cross section and sig - nificantly reduced manning (no operators). The radar performs such functions as horizon search, limited above-the-horizon  search, and fire control track and illumination. 
 1959.  115. Miller. 
 If a  current of opposite polarity is passed through the drive wire, the ferrite is saturated with the  opposite polarity of remanent magnetization. Thus a toroidal ferrite may take on two values of  magnetization. ± B,, obtained by pulsing the drive wire with either a positive or negative  current pulse. 
 PROPAGATION BOTH FOR COHERENT AND NONCOHERENT RADARS RANGE AND VELOCITY RESPONSES IN COMPLEX . 
 ANGULAR PULSE  4HIS ATTENUATES THE SPECTRUM OF FREQUENCIES FAR FROM  FO  WHILE THE FLAT 
 1976.  82. Leth-1:srl'tlsrn. 
 Weather echoes are a nuisance to the  radar operator whose job is to detect aircraft or ship targets. Echoes from a storm, for  example, might mask or confuse the echoes from targets located at the same range and  azimuth. On the other hand, radar return from rain, snow, or hail is of considerable impor-  tance in meteorological research and weather prediction. 
 Digital technology, how - ever, presents the radar system designer with many more options and allows arbi - trarily modulated transmit waveforms to be modified pulse-to-pulse if desired. This  section describes several of the techniques commonly used to generate the radar  transmit signal digitally. Direct Digital Synthesizer (DDS). 
 M r  
 5214–5217. 28. Eriksson, L.E.B.; Sandberg, G.; Ulander, L.M.H.; Smith-Jonforsen, G.; Hallberg, B.; Folkesson, K.; Fransson, J.E.S.; Magnusson, M.; Olsson, H.; Gustavsson, A.; et al. 
 This table gives the decibel  attenuation per kilometer for different rainfall rates for radar wavelengths between  0.3 and 10 cm. FIGURE   19. 1 Theoretical rain attenuation in dB/mile (statute)  versus rainfall rate ( after J. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar.  METEOROLOGICAL RADAR  19.436x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 48. 
 BASED REFLECTOR ANALYSES AS SHOWN HERE IS A SPECIALIZED CASE WHEREIN THE REFLECTOR IS AN ELECTRIC CONDUCTOR  AND CONTRIBUTIONS FROM SURFACE CURRENTS ON THE BACKSIDE OF THE REFLECTOR ARE DEEMED NEGLIGIBLE !N APPROPRIATE APPLICATION OF IMAGE THEORY n IMPOSES A ZERO TANGENTIAL  % 
 IEEE , vol. 73, pp. 228–232, February 1985. 
 Evidently, where  the RF waveform is changing rapidly, jitter in the sampling circuits results in a very  noisy reconstructed waveform. Where the rate of change of signal is slow, jitter is less  noticeable. Normally, control of the sampling converter is derived from a sample of  the output from the pulse generator to ensure that variations in the timing of the latter  are compensated automatically. 
 F. Kauffman: A High Temperature Luneburg Lens, Proc. IEEE. 
 PARALLEL  COMBINATIONS /NE MEMBER OF EACH PAIR IS DUE TO THE TOTAL SURFACE CURRENT ON THE DIFFRACTING EDGE INCLUDING THE ASSUMED FILAMENTARY EDGE CURRENTS   AND THE OTHER IS DUE TO THE UNIFORM PHYSICAL OPTICS CURRENTS -ITZNER SUBTRACTED ONE MEMBER OF EACH PAIR FROM THE OTHER  THEREBY RETAINING THE CONTRIBUTIONS FROM THE FILAMENTARY EDGE CURRENTS ALONE 4HE RESULTS HAVE THE IDENTICAL FORM OF 5FIMTSEVS EXPRESSIONS  IN WHICH THE 0/  COEFFICIENTS ARE SUBTRACTED FROM THE NON 
 56. Twersky, V.: On Scattering and Reflectiotl of Electromagnetic Wavcs hy Rougti Surfaces. IRE  Trans., vol. 
 LIMITED TARGETS 4HE -273 WAVEFORM USES  - 
 267. Sensors 2019 ,19, 2605 The equations can then be solved iteratively for other pixels with: fk+1=A−1g(¯fk), (10) where kis the iteration number. This way the matrix A−1need only be computed once. 
 Radar wavesarediffracted aroundthecurvedearthinthesamemannerthatlightisdiffracted bya straight edge.Theabilityofelectromagnetic wavestopropagate aroundtheearth'scurvature bydiffraction depends uponthefrequency, ormoreprecisely, uponthesizeoftheobject compared withthewavelength. Thelowerthefrequency, themOrethewaveisdiffracted. The mechanism ofdiffraction isespecially importan~ atverylowfrequencies (VLF)whereit provides world-wide communications. 
 7.7. The maximurn of the curve is relatively broad, so that the optimum  angle subterided by the antenna at tlie focus is not critical. The greatest efficiency is obtained  with n rcflcctor in wt~icti the ratliation fro111 tlle reed in the direction of the edges is between 8  arid 12 dl3 below tliat at the cetltel-. 
 LEVEL OUTLINE OF SOME OF THE MAJOR DIGITAL PRO 
 In this implementation the last block labeled (PASS/INV) performs   the required inversion of I and Q if the desired phase shift is beyond the ±90o range of  the algorithm. The final multiplication by a constant is optional, as described earlier. The architecture shown in Figure 25.29 is a good example of a pipelined  processor,  in which a portion of the computation is performed and the result is stored in a register  on each rising edge of the sample clock and passed to the next stage of processing. 
 Reducing scan time (increas-  ing rotation rate) requires at1 increase in the average power and/or antenna six. Some long-  range military radars have rotation rates of 15 rpm (44 scan time) because of the likelihood  of target maneuver. A rapid change of course is less likely for civilian aircraft: hence. 
 1971.  80. Kabilicr, L. 
   05,3% #/-02%33)/. 2!$!2   n°ÎÇ 2ADAR 4RANSMIT 7AVEFORMS  n 4HE TRANSMITTED WAVEFORMS USED IN RADAR  ARE BANDPASS SIGNALS THAT CAN BE EXPRESSED IN THE FORM   XT AT FT T   COS;  =  PF    WHERE AT  IS THE AMPLITUDE MODULATION  6   ET  IS THE PHASE MODULATION RAD   AND  F IS THE CARRIER FREQUENCY (Z  4HE AMPLITUDE AND PHASE MODULATION FUNCTIONS VARY  SLOWLY COMPARED TO THE PERIOD OF THE CARRIER  F  #ONSEQUENTLY   XT  IS A NARROWBAND  WAVEFORM WITH A BANDWIDTH THAT IS SMALL COMPARED TO THE CARRIER FREQUENCY  #OMPLEX %NVELOPE  4HE COMPLEX ENVELOPE OF XT  IS GIVEN BY   UT ATEJT     F  A 4!",%    3IGNAL !NALYSIS $EFINITIONS AND 2ELATIONSHIPS  #ONTINUED     #OSINE AND SINE FUNCTIONS EXPRESSED  IN TERMS OF COMPLEX EXPONENTIALSCOS    SIN   Q QQQ QQ 
 DIRECTION MODULATION  RATIO FOR A SOYBEAN FIELD WITH HORIZONTAL POLARIZATION AT INCIDENCE ANGLES  OF     AND  AFTER & 4 5LABY  2 + -OORE  AND ! + &UNG  . 
 TRACING CODES DEVELOPED OVER THE YEARS  THE IMPLEMENTATION BY *ONES AND 3TEPHENSON  BASED ON INTEGRATION OF THE FIRST 
 F. Knott, “The relationship between Mitzner’s ILDC and Michaeli’s equivalent currents,” IEEE  Trans ., vol. AP-33, pp. 
 V . G. Somov, V . 
 It is also possible to scan  the beam with electronic phase shifters. With a scanning phased-array antenna, however, the  radiation pattern, which is a fan beam at broadside, becomes a conical beam when scanned ofT  broadside. This can cause an error in the elevation measurement if the target is ofT the center of  the beam. 
 The reduction in length is  essentially equal to the wind-up factor of the helix, which is the ratio of the circumference to  the pitch. Wind-up factors may range from 10 to 20 in practical designs.  Both the coax and the helical line-stretchers are not well suited for the higher microwave  frequencies. 
 Lett. 2014 ,11, 133–137. [ CrossRef ] 21. 
 Geosci. Remote Sens. 2015 ,53, 1225–1235. 
 l og( ) log( ) (26.12) where f  is frequency in MHz and r is the distance between the transmitter and receiver  in kilometers. Free space is included in many modeling applications as a reference for  other propagation effects. If nonisotropic antenna radiational patterns are considered within the loss calcula - tions, the loss is referred to as a propagation loss rather than a path loss. 
 V . Zhary, A. D. 
 .The phase  history is then used for compensating the range migration and the phase shift on  the high [fine] resolution range data. The final image is shown in Figure [17.10 b].   The sharpening of the target image is quite evident.” Barbarossa and Farina assumed  a point target in their simulation. 
 20. P. W. 
 The bandwidth of such a radome is limited, as is  the range of inciderice angles over which the energy is transmitted with minimal reflection.  The A sandwich is a three-layer wall consisting of a core of low-dielectric-constant mater-  ial with a thickness of approximately one-quarter wavelength. This inner core is sandwiched  between two thin outer layers, or skins, of a high-dielectric-constant material relative to that of  the core. 
 to unity at midband (maximum-response frequency),  H( fo) = 1. The bandwidth Bn is called the noise bandwidth and is the bandwidth of an equiva-  lent rectangular filter whose noise-power output is the same as the filter with characteristic  18INTRODUCTION TORADAR SYSTEMS parameters thatmustbedetermined inordertocompute theminimum detectable signal, Although thedetection decision isusuallybasedonmeasurements atthevideooutput,itis easiertoconsider maximizing thesignal-to-noise ratioattheoutputoftheIFamplifier rather thaninthevideo.Thereceivermaybeconsidered linearuptotheoutputoftheIF.Itisshown byVanVleckandMiddleton3thatmaximizing thesignal-to-noise ratioattheoutputoftheIF isequivalent tomaximizing thevideooutput.Theadvantage ofconsidering thesignal-to-noise ratioattheIFisthattheassumption oflinearity maybemade.Itisalsoassumed thattheIF filtercharacteristic approximates thematched filter,sothattheoutputsignal-to-noise ratiois maximized. 2.3RECEIVER NOISE Sincenoiseisthechieffactorlimitingreceiversensitivity, itisnecessary toobtainsomemeans ofdescribing itquantitatively. 
 17.18 is the single-scan probability of detection Pd versus range for a given RCS target in a receiver with unlimited dynamic range. If it is desired to have the low-flying target reach at least, say, an 80 percent Pd before any gain limiting occurs, the dynamic-range requirement due to main-beam clut- ter is 53 dB at 1000 ft, 44 dB at 5000 ft, and 41 dB at 15,000 ft for this example. As is evident, the higher the desired probability of detection or the lower the radar altitude, the more dynamic range that is required. 
 Since the elevated  duct is due to meteorological effects there are seasonal, as well as diurnal, variations. The  optirnunl seasori for duct formation in the tradewind region between Brazil and Ascension  islarids occurs in N~vernber.~~ It has been said, however, that elevated ducts giving rise to  strong persistent anomalous propagation occur throughout most of the year over at least  one-third of tile ocea~is.~'  To take maximum advantage of propagation in an elevated duct, the radar and target  slioi~ld he at an altitude tiear tliat of tlie duct. This is found from both theory and measure-  metlts made by aircraft flying at various altitudes. 
 The related radar parameters are listed in Table 4. Frame B (24 km ×24 km) highlights a shear-wave-generated eddy with a diameter of about 24 km, which is shown in detail in Figure 9. In Figure 8, oceanic wakes generated by the island in the upper right corner of the image also exist, but this is beyond the scope of this paper. 
  N 0 ;ONE SIDELOBE   24=  ! SIMPLE EXAMPLE WILL ILLUSTRATE THE PROCESS )F IT IS NECESSARY TO KEEP ALL  SIDELOBES  IN A SECTOR BELOW  
 V . W. Pidgeon, “Doppler dependence of sea return,” J. 
 Itis important toavoidreceiver saturation, oroverloading. Awidedynamic rangeisdesired. and. 
 ELEMENT MONOPULSE FEED WITH DUM  DELTA AZ  AND DELTA EL PORTS. 
 23-42, July, 1977.  44. Butler, N.: The Microwave Tubes Reliability Problem, Microwave J., vol. 
 The antenna beam shape is approximated by a gaussian function in the calcula-  tions leading to Fig. 5.6. The greater the slope of the error signal, the more accurate will be  the tracking of the target. 
 20.2 is the “slant range,” that is, the length of the sky - wave path between target and radar, not the distance as measured along the Earth’s  surface. The ionospheric reflection height needs to be used to convert this slant  range to great-circle ground distance. The apparent range to a particular target may  take on more than one value since multiple paths may exist. 
 RADAR MODEL TO CALCULATE FREE 
 PROCESSING  CAPABILITY  MEASUREMENT ACCURACY REQUIREMENTS  ETC  BUT OFTEN DEPENDS ON THE    NEED FOR ALL 
 19, pp. 157-167, March-April 1980. 14. 
 The Boeing Company unveiled a mockup  of the “C” version of its unmanned combat vehicle in the mid-2000s, less than a  decade after the project was funded by the Defense Advanced Research Projects  Administration (DARPA). An Associated Press photo of the aircraft mockup is shown  in Figure 14.32. The airframe is 49 ft wide and 39 ft long. 
 FREQUENCY 3I "*4 PERFORMANCE IS THE OVERALL  COLLECTOR 
 ING FREQUENCIES WHERE THE OCEAN WAVE SPECTRUM WAS APPROXIMATELY FULLY DEVELOPED THESE OBSERVATIONS PROVIDED A CONFIRMATION OF "ARRICKS FIRST 
 Ground based synthetic aperture radar for land deformation monitoring: Preliminary result. In Proceedings of the 2016 Progress in Electromagnetic Research Symposium (PIERS), Shanghai, China, 8–11 August 2016; pp. 2540–2542. 
 GAIN JAMMING  IT IS USED TO CAPTURE THE  ANGLE 
 A DC supply was also required for the blower or cooling fan (see table 2.1), which blew air down the Lecher line tubes onto the valve anodes. The transmitter weighed 54 lb and its dimensions were 18 inch by 12 inch by 20 inch. The transmitter was designed to produce a pulse of about 2.5 μs at a pulse repetition frequency (PRF) of about 400 c/s. 
 PLE  AT A ROTATION RATE OF  RPM  A MAGNETRON WITH  CAVITIES CAN TUNE ACROSS A BAND  TIMES PER SECOND #OAXIAL -AGNETRON  ! SIGNIFICANT IMPROVEMENT IN THE POWER  EFFICIENCY  STA 
 FORMS #OMPONENTS SUCH AS KLYSTRONS AND SOLID 
 RELATED PARAMETERS 4HE TRANSMITTER 
 It was also noted in [ 11] that the scanner tilt was about +2°above the best position. It was found in later trials that the trim of the aircraft had to be adjusted according to the load it was carrying in order to point the antenna as required with approximately zero tilt. 3.5 Improvements to ASV Mk. 
 (Courtesy Hlrglles Aircrufi Co.)  320INTRODUCTION TORADAR SYSTEMS Leichter's analysis IIIofbeam-pointing errorswasperformed foracontinuous line source,butmaybeappliedtoalineararray.Bothuniform distributions andmodified Taylor distributions wereconsidered. Theamplitude andphasedistributions weredescribed bythe gaussian distribution andwereassumed independent ofoneanother. Anexample ofLeichter's resultsforauniform amplitude distribution isshowninFig.8.30. 
 This pitch adjustment iselectrically driven and remotely controlled byhand. Asecond unusual feature isthe nature ofthe r-f elevation joint, which allows thebeam toberaised ordepressed from its normal attitude. This ismerely achoke-to-flange coupling, similar to the rigid coupling commonly employed (See Sec. 
 WAY HALF 
 17. F. J. 
 Merrill 1. Skolrlik  xPREFACE beenlimited. Omitted fromthissecondedition isthechapter onRadarAstronomy since interestinthissubjecthasdecreased withtheavailability ofspaceprobesthatcallexplorethe planetsatcloserange.Thebasicmaterial ofthefirsteditionthatcoverstheradarequation, thedetection ofsignalsinnoise,theextraction ofinformation, andthepropagation ofradar waveshasnotchanged significantly. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 For a 10,000-element array,  0 212 2 .( )=− + + P P PA aσ σ ηφ  For ha = 1, this array can tolerate P = 0.83, or sA = 3.2 dB, or sf = 25.6 °. 
 1. In addition, amplitude fluc- tuations in the RF drive will also cause drive-induced jitter, which may even ex- ceed power-supply-ripple-induced jitter, so this factor must be carefully measured. Spectral Emissions. 
 9.Ia Main and auxiliary antenna patterns for the SLB. (From Ref. 21.) MAlNCHANNEL MAINANTENNARECEIVERASQUARE-LAWDETECTORGATEDETECTIONTHRESHOLDINTEGRATIONANDTHRESHOLDING BLANKINGTHRESHOLD AUXILIARYANTENNA RECEIVER BSQUARE-LAWDETECTOR . 
 Experimental Simulation In order to verify the validity of the algorithm, the simulation data are used for explanation. The simulation resolution is 0.3 m ×0.3 m, the wavelength is 3 cm, the center frequency is10 GHz, the signal bandwidth is 500 MHz, the range sampling rate is 600 MHz, the pulse width is 3.5 μs, the speed of aircraft is 100 m/s, the antenna aperture is 0.6 m, and the pulse repetition frequency is 450 Hz. The closest distance from the center of the scenario to the aircraft route is 30 km. 
 94. Blacksmith. P .. 
 NORMAL DISTRIBUTIONS ARE TYPICAL FOR BENIGN CONDITIONS 4RACKING 0ERHAPS THE MOST FUNDAMENTAL DIFFERENCE BETWEEN SKYWAVE RADAR  AND OTHER RADARS IS THE EXISTENCE OF MULTIPLE PROPAGATION PATHS  WITH DISTINCT TIME DELAYS  ANGLES OF INCIDENCE  DOPPLER SHIFTS  AND FLUCTUATION PROPERTIES 4HE TRACKING STAGE MUST DEAL WITH THE MULTIPLICITY OF ECHOES ASSOCIATED WITH EACH INDIVIDUAL TARGET AND  BY EXTRACTING AND ASSIMILATING INFORMATION ABOUT THE PREVAILING IONOSPHERE  INFER THE NUMBER OF GENUINE TARGETS  THEIR TRUE LOCATIONS AND VELOCITIES  AND PERHAPS . 
 Thepowerhandling capability ofamagnetron depends onitssize.Increasing thesizeofa magnetron, however, requires increasing thenumberofresonators. Thegreaterthenumberof resonators themoredifficulttheproblem ofmodeseparation. Sincethemodeseparation ina coaxialmagnetron iscontrolled intheTEollstabilizing cavityratherthanintheresonator area,thecoaxialmagnetron canoperatestablywithalargenumberofcavities. 
 ALLY THE RADAR REQUIREMENTS OF DOPPLER TOLERANCE AND TIME SIDELOBE LEVELS 4ABLE  SUMMARIZES THESE FACTORS FOR THREE &- TYPES ,&-  .,&-  AND PHASE 
 TIONS OR MODELS  EMPHASIZING DIFFERENT ASPECTS OF THE IONOSPHERE AND ITS INFLUENCE ON RADIOWAVE PROPAGATION AND  HENCE  (& RADAR PERFORMANCE )N MANY  CASES OF PRACTICAL  INTEREST  IONOSPHERIC MODELS DEVELOPED ORIGINALLY FOR (& COMMUNICATIONS PURPOSES . Óä°£{  2!$!2 (!.$"//+  CAN BE ADAPTED TO THE RADAR CONTEXT  WHERE THE MAIN DIFFERENCE IS THE GREATER SENSITIV 
 S. Symons and J. R. 
 4  WAVEGUIDE COMPONENTS 4HESE ARE FOUR 
 Imperfections oftheFIG. 313,—Scheme forreduction ofrain echo. quarter-wave plate, aswell asthe slight ellipticity offalling raindrops, prevent complete cancellation ofthe rain echo. 
   NO   PP n  *UNE   7 - (ALL AND ( 2 7ARD  h3IGNAL 
 Thus the width of the element on the ground is related to the doppler fre- quency bandwidth by R\Ap = —(A/d) Where this technique is applied to the radar equation and the following are assumed: 1. a° constant in the illuminated area FAN BEAM FIG. 12.15 Resolution in a fan-beam CW-doppler scatterometer. 
 Headrick, Naval Research Laboratory (CHAPTER 24) Dean D. Howard, Locus, Inc., a subsidiary of Kaman Corp. (CHAPTER 18) Alex Ivanov, Missile Systems Division, Raytheon Company (CHAPTER 19) Eugene F. 
    PP n    ! ,USCOMBE  ! 4HOMPSON  0 *AMES  AND 0 &OX  h#ALIBRATION TECHNIQUES FOR THE 2!$!23!4 
 Results showed improvements with respect to other refocusing methods. The work in [ 18] also deals with ship detection. It proposes a method that performs ship classiﬁcation by processing SAR images through convolutional deep neural networks (CNN). 
 But on this occasion only  very isolated towns could be picked up and located,  owing to the overlapping of the responses from hills and  woods included in the ‘illumination’ of the ground by  the relatively broad transmitted beam. Even at that  early date British scientists could see that, given a  higher-frequency transmitting system to produce almost  a pencil of radiation, more detailed illumination of the  ground could be achieved, and then a cockpit ‘television’  picture system might be devised to show a useful map  of the ground.  But the autumn of 1941 demanded immediate opera-  tional results, so an aircraft was adapted for ‘downward-  looking,’ with a bowl-shaped reflector pointing towards  the ground; this showed immediate promise on its first  test flight from Christchurch to Wolverhampton, in that  a series of ‘target’ towns and other objects were seen  on the radar display, and after the flight 1t was found  possible to correlate these with specific objects on the  . 
 To extract the modulation envelope, the video bandwidth must be wide  enough to pass the low-frequency components generated by the second detector, but not so wide  as to pass the high-frequency components at or near the intermediate frequency. The video  bandwidth B,, must be greater than BIF/2 in order to pass all the video modulation. Most radar  receivers used in conjunction with an operator viewing a CRT display meet this condition and  Second  detector - V~deo  amplifier  (Bv) . 
 For N = 255, the peak sidelobe varies from - 21.3 dB to - 22.6 dB, instead of the - 24 dB predi~ted.~'  The binary codes generated in this manner fit many of the tests for randomness. (Ran-  domness, however, is not necessarily a desirable property of a code used for pulse compres-  sion.) The number of ones in each sequence differs from the number of zeros by at most one  (the balance property). Among the runs of ones and zeros in each sequence, one-half of the  runs of each kind are of length one, one-fourth are of length two, one-eighth are of length three,  and so on (the run property). 
 Inspiteofthe limitations, there does existabodyofinformation regarding theradarechofromthesea,some ofwhichwillbereviewed brieflyinthissection. Average valueof0'0.Acomposite averageofseaclutterdataisshowninFig.13.3.1Thisisa plotofthemeancrosssectionperunitarea,0'0,asafunction ofgrazingangleforvarious frequencies andpolarizations. Itdoesnotcorrespond toanyparticular setofexperimental II " Idata,butitrepresents whatmightbetypicalof"average" conditions. 
 Hence, there will beno bias error over water. A very narrow antenna beam will also reduce the  over-water bias error without the need for lobe switching. Another source of error is the mass  movement of water caused by tides, currents, and winds, which result in a doppler frequency  shift in addition to that caused by the aircraft's motion. 
 Forinstance, thehighsidelobes thataccompany auniform illumina­ tionareseldomdesired, andtheaperture efficiency isusuallywillingly sacrificed forlower sidelobes. Whenashapedbeamisdesiredinasurveillance radar,suchasacosecant-squared pattern, againitismoreimportant toachievetheoverallpatternrequired ratherthansimply max'imize thedirectivity atthepeakofthebeam. Aperture efficiency isameasure oftheradiation intensity onlyatthecenterofthebeam. 
 Bass. F. G., I. 
 Croney, J.: Civil Marine Radar, chap. 31 of " Radar Handbook," M. I. 
 CHAPTER 16 MOVING-TARGET INDICATION BYA.G.EMSLIE AND R. A. MCCONNELL INTRODUCTION 16.1. 
 ALS   AT LEAST ONE UNWANTED CHARACTERISTIC REMAINS 4HE + TIDAL ALIAS IS VERY NEARLY TWO  CYCLES PER YEAR  THUS APPEARING CLOSE TO GEOPHYSICAL SIGNALS ASSOCIATED WITH SEASONAL EFFECTS + CANNOT BE IGNORED  AS IT IS THE LARGEST DIURNAL CONSTITUENT AND IS SECOND IN MAGNITUDE ONLY TO THE DOMINANT LUNAR CONSTITUENT 4HE CONSTRAINT ON THE EXACTNESS OF AN ORBITS REPEATING GROUND TRACK IS DETERMINED TO  FIRST ORDER BY THE FINE STRUCTURE IN THE LOCAL GEOID EXPRESSED AT THE OCEANS SURFACE  &OR  EXAMPLE  CROSS 
 5.3. Third, a line-of-sight velocity measurement, VLOS, using doppler  and/or range rate, is made also using centroiding. Because terrain may be rising or fall - ing at the illuminated patches giving rise to velocity errors, terrain slope is estimated  and used to correct the estimated velocity. 
 The RF frequency of the Varian SFD-354A  X-band coaxial magnetron can be varied sinusoidally over a 60-MHz range at a rate of 70  times per second by this method. 200 INTRODUCTION TO RADAR SYSTEMS  Magnetic field lines  Coupling slot  Vane resonator  Cavity mode  attenuator  TE011 mode  Electric field  RF  output  waveguide  \ Output vacuum  window  Vacuum bellows  attenuator  Cathode  Tuning piston ..  Figure 6.8 Schematic view or a coaxial magnetron showing  the tuning piston mechanically actuated by a vacuum  bellows. 
 M. Vaughan, “The linear theory of the clustered cavity klystron,” IEEE  Trans. , vol. 
 ING AT THE EQUATOR   AND  KM ALTITUDEe &ROM THE 'EOSAT ORBIT  HALF OF THE PRINCI 
 FIGURE 13.38  Array architectures for analog and digital beamforming ch13.indd   56 12/17/07   2:41:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 CONSCIOUS  BASED ON RIGID NONDEPLOYED  REFLECTOR ANTENNAS hBORROWEDv FROM A COMMERCIAL COMMUNICATIONS SATELLITE PRODUCTION LINE  THAT ARE INHERENTLY MORE EFFICIENT AND LESS MASSIVE THAN AN ACTIVE ARRAY 4HE RADAR ELECTRONICS ARE DIRECTLY DESCENDED FROM A COMMERCIAL PRODUCT LINE 2)3!4 4HE 2ADAR )MAGING 3ATELLITE  OR 2)3!4  IS )NDIAS FIRST SPACE 
 ● The invention of the microwave magnetron and the application of waveguide tech - nology early in WWII to obtain radars that could operate at microwave frequencies  so that smaller and more mobile radars could be employed. ● The more than 100 different radar models developed at the MIT Radiation  Laboratory in its five years of existence during WWII that provided the foundation  for microwave radar. ● Marcum’s theory of radar detection. 
 ,#% -( )*" !"*   ,#% -( +"  
 Each ofthese cavities issimilar toasimple oscillating circuit consisting ofalumped Land C. Although the inductance and capacity ofthe magnetron cavity are not strictly lumped, the inductance ofthe oscil-. SEC. 
 The choice of receiving antenna element has traditionally been based on the precept  that, at HF, the external noise almost always exceeds the internal noise by a substantial  margin. On this logic, improving antenna efficiency increases the output external noise  and interference amplitude at the same rate that it improves the wanted signals, thereby  gaining no advantage in SNR. Selection of antenna element type, such as monopoles,  dipoles, Beverage antennas, phased endfire rows of monopoles, or biconical anten - nas, for instance, can then be based on frequency response over the anticipated band  of interest and suitability for the chosen array geometry, as well as terrain constraints  such as the soil conductivity. 
 $ 7IRTH   2ADAR 4ECHNIQUES 5SING !RRAY !NTENNAS  )%% 2ADAR  3ONAR  .AVIGATION AND  !VIONICS 3ERIES   ,ONDON 4HE )NSTITUTION OF %LECTRICAL %NGIN EERS      2 , &RANK  h0OLYPHASE CODES WITH GOOD NONPERIODIC CORRELATION PROPERTIES v  )%%% 4RANS    VOL )4 
 vol. 6. Frcqirericy Agility and Diversity." Artech House. 
 Fitzgerald, “Simple tracking filters: Steady-state filtering and smoothing performance,”  IEEE Trans. Aerospace and Electronic Systems , vol. AES-16, pp. 
 E. Nathanson, Radar Design Principles , 2nd Ed., New York: McGraw-Hill Book Company,  1991.  4. 
 Some comments  should be made, however, about the practical utility of these characteristics. These attributes  are obtained for a price, so that they should only be considered when warranted. It is not  obvious that they are always absolutely essential for the success of a particular application. 
 155.  98. Ko~siakoli. 
 M DIAMETER DISH  WAS A SIGNIFICANT DEPARTURE FROM THE CONVENTIONAL HIGHLY ASYMMETRIC RECTANGULAR ANTENNAS THAT WERE THEN IN FAVOR FOR 3!2S &)'52%   !RTISTS IMPRESSION OF -AGELLAN OBSERVING THE SURFACE  OF 6ENUS  BACKLIT BY THE SUN  FEATURING THE RADAR AND HIGH 
 First published 1948  by Gzorce G. Harrar & Co. Lip  182 High Holborn, London, W.C.1  Copyright. 
 153. Y. Senbokuva, S. 
 M.: Complex Indicated Angles Applied to Unresolved Radar Targets and Multipath.  IEEE Trans. vol. 
 RANGE RESOLU 
 All GPRs may have to detect signals from a target that may be –50 to –100 dB  lower than the radiated signal at ranges in the order of a meter (6.6 ns in free space). In  addition, the received signal will contain temporal scattering information on the target  that can be exploited. The temporal fidelity of received signal needs to be preserved and thus designers of  GPR have to ensure that the receiver is not saturated by the transmitted signal, the anten - nas do not cause time sidelobes, and the receiver does not distort the received signal. 
 , ..  Circular polarization can be selected to reduce weather clutter. MTI and the log-CF AR . 
 Some channels in the array are dedicated to other functions such as calibration,  jammer nulling, sidelobe blanking, close in missile datalink, out-of-band direction  finding, etc.19,25,26, 27 Also, there are usually some channels at the edge of the array that  are passive and improve the sidelobes and RCS pattern.8 Figure 5.9 shows the comparison between a conventional mechanically scanned  radar with the low-noise amplifier and a high-power traveling wave tube transmit - ter mounted off the gimbal versus a real-time adapted AESA with two different scan  regimes for the same amount of input prime power. AESA performance falls off for  large scan coverage because of the lower projected aperture area for a fixed mounting as  shown in Figure 5.1. A mechanical scan has the same projected area in all directions and  large scan angles marginally reduce radome losses, which results in slightly improved  large angle performance. 
 ON 
                
 9.28, isdriven byamotor inthe box attached tothe horn. The parallel-plate horn serves totransform thecircularly moving waveguide feed into anappar- ently linearly moving source. The beam scans 10.5° inelevation for each rotation ofthe guide. 
 9, no. 3, pp. 364–380, 1952. 
 17.28  Types of Spurious Modulation  ............................  17.29  Sinusoidal Modulat ions  ......................................  17.29  Pulse-to-Pulse Random  Modulation  ................... 
  AND POST 
 FREQUENCY (&  BAND  TO  -(Z  4HIS VERY LONG RANGE COVERAGE IS OBTAINED BY USING  SKYWAVE PROPAGATION  THAT IS  REFLECTING  THE RADAR SIGNALS FROM THE IONOSPHERE (& GROUND WAVE SURFACE WAVE  PROPAGATION OVER THE SEA HAS BEEN USED FOR INTERMEDIATE BUT STILL OVER 
 / 
 FIG.6.20.—Elevation coverage diagram.The lobes arefewinnumber and very w-ide. Asecond antenna, placed atadifferent height, produces asecond series oflobes which overlap those ofthefirst antenna. The echo strength foronelobe system iscom- pared with that forthelobe system from the other antenna. 
 Amplitude measurement error: The root -mean -square error is  € ∂U=n2 (5.2)  The relative error then becomes   € ∂U U=n2 U02=1 (2Ueff)2 n2=1 2SN (5.3)  Time measurement er ror: The time error ∆t according to Figure 5.1 is  . Radar Systems Engineering  Chapter 5 – Resolution and Accuracy  24     slopetnt)(=Δ  (5.4)  For the sine function the is (at zero crossover crucial for the measurement) ω U o, from which  follows:  NS Un Unt t eff o /21 22 2 2 ω ω ω= = =Δ=∂  (5.5)  Phase error: The phase error results direct ly:  NStf /212 =∂⋅ =∂ π φ  (5.6)  Period error: The period error ∂T (RMS) is larger than ∂t by around a factor of  2, since two  passes are to be measured.   NST NST / 2 /22 π ω= =∂  (5.7)   The relative errors for the period and the frequency are then:   NS TT / 21 π=∂ (5.8)  NS ff / 21 π=∂ (5.9)  5.2 Accuracy and Range Measurement  For calculating the accuracy of the range measurement one replaces the sine wave with a video  pulse as in Figure 5.2. 
 13.25 gives  Number ofphase-shifterbits, Loss ingP2 3 4 a ain d B 1.0 0.23 0.06 ∆G,  From the point of view of gain, therefore, 3 or 4 bits would appear ample. RMS Sidelobes . Phase quantization decreases the gain of the main beam, as  shown above. 
 Following onboard processing, the average data rate is 40 kbits/s. SeaWinds perfor - mance139 is at least comparable to other wind scats, wind speed and direction accuracy  being 3 m/s to 20 m/s at 2 m/s and 20 °, respectively. Nominal surface resolution is   50 km; advanced processing140 reduces this to ∼25 km. 
  OR LAGGING 
 E. Sollenberger: Optimum Pulse-Time Determination, IRE Trans., no.  PGIT-3, pp. 
 Waveguide Models.  As engineering requirements demanded greater and greater  fidelity, other modeling techniques were developed. One such modeling technique is  using normal mode theory to compute field strength under standard or nonstandard  refractive conditions. 
 Taylor: Terrain Scattering Properties for Sensor System  Design (Terrain Hand hook II). E11gi11eeri11g Experiment Station Bulletin 110. 181. 
 DIMENSIONAL VECTOR  7   7  7   x  7.  4HE JAMMING SIGNAL IS CANCELED BY A LINEAR COMBINATION OF THE SIGNALS FROM THE  AUXILIARIES AND THE MAIN ANTENNA 4HE PROBLEM IS TO FIND A SUITABLE MEANS OF CONTROLLING THE WEIGHTS  7 OF THE LINEAR COMBINATION SO THAT THE MAXIMUM POSSIBLE CANCELLATION IS  ACHIEVED /WING TO THE STOCHASTIC NATURE OF THE JAMMING SIGNALS IN THE RADAR AND IN THE AUXILIARY CHANNELS AND TO THE HYPOTHESIZED LINEAR COMBINATION OF SIGNALS  IT IS ADVIS 
 158  14 Future Radar Systems ...................................................................................................... 162  14.1 The Transmit Subsystem .............................................................................................. 162  14.2 The Receiver Subsystem ............................................................................................... 
 1970. 46.Ulaby.F.1'.,W.H.Stilcs,L.F.Dellwig. andB.C.Hanson: Experiments ontheRadarBackscatter of Snow.IEEETrans.,vol.GE-15.pp.185-189. 
 BASED RADAR ALTIMETRY 4HIS METHOD WAS FIRST EMPLOYED BY -AC!RTHUR IN THE 3EASAT ALTIMETER   AND HAS BEEN ADOPTED AS THE STANDARD TECHNIQUE SINCE THEN FOR THIS TYPE OF  RADAR 4HE DISTINGUISHING FEATURE OF THIS TECHNIQUE IS A CLEVER TRADE BETWEEN THE TWO KEY &)'52%   ! GENERIC SIGNAL FLOW DIAGRAM FOR AN OCEAN 
 Microwave radiation is nonionizing and is vastly difft!rcnt  from ionizing radiations such as X rays.  As a safety precaution, areas of high power density should be fenced off, lockcd, or  otherwise made inaccessible when transmitting. Personnel should never look into an open  waveguide or antenna feed horn connected to energized transmitters. 
 Scjltct~iI>cr. 1965.  119. 
 We reconstruct the subaperture images with BP , CS, debiased-CS and LS-CS-Residual. To compare the aspect dependent scattering reconstruction performance of the three methods, we add the intensities of these pixels together and plot the results in Figure 5. Figure 5is the main valid scattering area of the reﬂector. 
 42 
 The  radar equation for a microwave surveillance radar was given by Eq. (2.57). This must be  modified for an HF radar since the coherent integration time T.: is fixed in an HF radar by the  doppler processing requirements. 
 36 OSU-ESL SATCOM Workbench GUI, offset Gregorian reflector model and pattern ch12.indd   35 12/17/07   2:31:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 
 With a single short pulse, the doppler frequency shift will be small  compared to the receiver bandwidth so that only one matched-filter is needed for detec-  tion, rather than a bank of matched filters with each filter tuned for a different doppler  shift.  A short-pulse radar is not without its disadvantages. It requires large bandwidth with the  possibility for interference to other users of the band. 
  AND 6 
 Kadar antennas located in tlic nose of aircraft, however, generally require an ogive-shaped  radonle whicli does not 17rcscnt the same environment for all beam positions. When  tl~c aritcrlria is directed lo~ward (cne~gy ~)~oj>:~gating parallel to tlie radome axis) the angle of  incidence on the radorne surface can be in excess of 80". In other look directions the incidence  ;~r~glc might be zero degrees. 
 4. Hildebrand, P., and C. Mueller: Evaluation of Meteorological Airborne Doppler Radar, Part I: Dual-Doppler Analyses of Air Motions, J. 
 L. Cosgriff, W. H. 
 Ithasbeenreported IIthatatXhand,smallshipsstand outmuchbetterwitharhorizontal beamwidth antenna thanwhenilluminated bya0.85° beamwidth antenna. Thisiscontrary towhatwouldnormally beexpected iftheclutterwere uniform. J Thus,astheresolution cellsizeisdecreased thenatureoftheseaclutterchanges. 
 The low-frequency-amplifier hand­ width must be sufficiently wide to encompass the expected range of beat frequencies. Since tile  bandwidth is broader than need be to pass the signal energy, the signal-to-noise ratio is  reduced and the receiver sensitivity degraded. Instead of maintaining the frequency excursion  flf constant and obtaining a varying beat frequency, 4f can be varied to maintain the heat  frequency constant. 
 S. Air Force  Systems Command, Foreign Technology Division Doc. FTD-HC-23-259-71, 1971. 
 Such rather simple difficulties could be,and often were, the limiting factors ontheuse that could bemade oftheradar plots, and anintensive study ofallthestages inplotting and filtering was made throughout the early years ofthe war. Despite thelarge number ofpeople necessary tothis system, and its prodigal useoftelephone land lines forthetelling ofplots, itsoperational limitations were severe. Under conditions ofmoderate aircraft density, agood filter officer with agood organization could filter plots with an accuracy ofperhaps 70percent. 
 SIGHT IS ABOUT  NMI  BUT THE CLUTTER ACTUALLY GOES OUT TO  NMI 4HE BRIDGES ACROSS THE INTRACOASTAL WATERWAY CAN BE SEEN /N OCCASION  THE UNWANTED LONG 
 MOISTURE CONTENT (%) FIG. 12.4 Apparent relative dielectric constant versus moisture content (Richfield silt loam). (After Lundien.24) ference between the roughness of a city with flat walls interspersed with win- dowsills, with curbs, cars, and sidewalks, and the roughness of natural areas is harder to see. 
 Mountain Relief .—The presence ofhills and mountains inthe area covered bytheradar presentation isindicated bythebright returns from the mountain sides facing toward the aircraft and bythe shadow regions onthe farside ofthe crests. These conditions follow directly from the geometry ofthe illumination, and produce avery realistic I‘l_herather diffuse rings ofintensification should notbeconfused with therange markers, which arenarro~ver andappear atequal radial intervals outtotheedge of thepicture.. 98 PROPERTIES OF RADAR TARGETS [six.3.14 surface interms ofasmall-scale relief model illuminated byarotating fan-shaped beam oflight, with the source oflight held above the model ataheight equivalent tothe altitude ofthe aircraft. 
 PRESSURE SYSTEMS  CENTERED AT APPROXIMATELY   NORTH AND SOUTH LATITUDE  COVER THE OCEAN AREAS OF THE WORLD 0OLEWARD OF THESE SYSTEMS LAY THE MID 
 67.Setter.LR.,D.R.Snavely, D.LSolem,andR.F.VanWye:"Regulations, Standards, andGuidesfor Microwaves. Ultraviolet Radiation. andRadiation fromLasersandTelevision Receivers-An An­ notatedBihliography," USDept.ofHealth,Education, andWelfare, PublicHealthServicePublica­ tionno.999-RH-35.April.1969. 
 ONLY RADAR SIGNAL ATTENUA 
 Skolnik (ed.), McGraw-Hill Book Co., Nc.:w  York, 1970, sec. 17.20.  98. 
 We have divided our time base into intervals I/@ long. Inone second than, @intervals come under observation. If(Bis2Me/see, for example, this amounts to2,000,000 intervals persec. 
 This is because of the high phase-modulation sensitivity of traveling- wave tubes and klystrons typically used as RF amplifiers. A linear droop of the modulating voltage will serrodyne the RF signal, shifting the peak of the spectral . envelope relative to the RF carrier frequency and reducing the useful signal power when passed through a filter matched to the pulse width. 
 ING 4HE COHERENCE REQUIREMENT DICTATES THE RELATIVE PHASE STABILITY OF ,/ AND !$ CONVERTER CLOCK SIGNALS USED FOR EACH RECEIVE CHANNEL 4HE  TIME SYNCHRONIZA 
 Compromises need to be made depending on the application. The radar equation for a surveillance radar (one that has to cover a fixed volume  of space on a regular basis) indicates that the maximum range of such a radar is pro - portional to ( Pav A)1/4, where Pav is the average power of the transmitter and A is the  area of the antenna aperture.1 A fundamental measure of the radar range performance  is therefore the power-aperture product . One can obtain a long range by having a  large antenna, a large transmitter, or a combination of both. 
 The  distance between them can be seen to be and ∆ ∆ρ θ θ λθ θ= − = −R fv d(sin sin ) (sin sin )2 1 2 12   Thus, the width of the element on the ground is related to the doppler frequency  bandwidth by  ∆ ∆ρλ=R vfd2( )  FIGURE   16. 15 Resolution in a fan-beam CW-doppler scatterometer ch16.indd   23 12/19/07   4:55:45 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 34!4% 42!.3-)44%23   ££°£Ç )N THIS EXAMPLE  A 'A!S 0(%-4 WITH  MM OF TOTAL GATE PERIPHERY &IGURE   IS  COMPARED WITH AN IDENTICAL  MM 'A. (%-4 &IGURE   4HESE FIGURES PORTRAY THE POWER OUTPUT  0O   POWER 
 Furthermore, it is not as temperature  sensitive, and there is less of a problem caused by hysteresis in the ferrite. The toroid ferrite  phase shifter. although not perfect by any means, has been in the past a popular choice for  phased array application. 
 ratios the square-law detector  may be a suitable approximation to the optimum detector, while for large signal-to-noise  ratios the linear detector is more appropriate. In practice, it makes little difference which of the  two detector laws is used. The difference between the square-law and the linear detectors was  shown by Marcum43 to produce less than 0.2 dB difference in the required signal-to-noise  ratio. 
 SURING POINT  THE REJECTION IS  OF ALL TARGET DOPPLERS FOR THE SINGLE CANCELER   FOR THE DUAL CANCELER  AND  FOR THE TRIPLE CANCELER #ONSIDER THE DUAL CANCELER %LIMINATING  OF THE DOPPLERS MEANS LIMITING THE SYSTEM TO A  LONG 
 The use of pulse compression provides several performance advantages. The  increased detection range capability of a long-pulse radar system is achieved with  pulse compression while retaining the range resolution capability of a radar that  uses a narrow uncoded pulse. The required transmitted energy can be established by Chapter 8 *  The authors would like to acknowledge the use of material previously prepared by Edward C. 
 Thesurestmethodforavoiding tracking errorduetomultipath reflections ,viathesurface oftheearthistouseanantenna withsuchanarrowbeamwidth thatitdoesn'tilluminate the surface.Thisrequires alargeantenna and/orahighfrequency.44 Although suchasolution eliminates theproblem, theremaybecompelling reasons insomeapplications thatmitigate againstthelargeantenna neededforanarrowbeamwidth oragainstoperation athigh frequency. Priorknowledge oftargetbehavior sometimes canbeusedtoavoidtheseriouseffectsof low-angle multipath withoutoverlycomplicating theradar.Sincetargetsofinterestwillnotgo belowthesurfaceoftheearth,andarelimitedintheirabilitytoaccelerate upward and downward, radardataindicative ofunreasonable behavior canberecognized andrejected. In somesituations, thetargetmightbeflyingfastenoughandtheinertiaoftheantenna maybe greatenoughtodampen theangle-error excursions causedbythemultipath:~7 Another solu­ tiontakesadvantage ofthefactthatlargeerrorsarelimitedtoaregionoflowelevation angles predictable fromtheantenna patternandtheterrain.Itisthuspossibletodetermine whenthe targetisinthelow-angle regionbysensing largeelevation-angle errorsandlockingthe antenna inelevation atsomesmallpositive anglewhilecontinuing closed-loop azimuth tracking.43Thisissometimes calledoff-axistracking,45 orofJ-boresight trackillg:PTheeleva­ tionangleatwhichtheantenna isfixeddepends ontheterrainandtheantenna pattern. 
 PLANE PATTERNS OF THE CENTER ELEMENTS OF WAVEGUIDES ARRAYS   AFTER " , $IAMOND Ú !RTECH (OUSE   . £Î°Ón  2!$!2 (!.$"//+  £Î°xÊ  "7- 
 13.18 gives further evidence of the threshold shadowing mentioned there. However, the common idea of shadowing, along with all existing theories of a shadowed surface, rests on the geometrical optics concept of a sharp transition between light and darkness. By considering the implications of diffraction at the wave peaks, it is possible to determine the domain of radar frequencies and wind speeds over which the concepts of geometrical optics may be applied. 
 This type of pattern may be generated by using one=  reflector dish with two feed horns side by side (four feed horns for two coordinate data). Since  the feeds may he placed side by side, they could be as close as one-half wavelcnglh. With such  close spacing the phase difference between the signals received in the two feeds is negligibly  small. 
 A  correctioti to tile measured elevation angle can be made using only the value of the index of  PROPAGATION OFRADAR WAVES455 focusing canchangetherelativeamplitudes ofthetwocomponents. Thefocusing effectcan evencausetheamplitude ofthcsurface-rellected raytosometimes exceedthatofthedirect ray.,'!lTheeffectoftheductonthelinc-of-sight propagation istoreducetheangleofthelowest lobe.bringing itclosertothesurface. Consequences ofduetedpropagation. 
 This sets a practical upper limit to  the si7e of an antenna that can have a Dolph-Chebyshev pattern and therefore sets a lower  limit to the width of the main beam which can be achieved.  'Ta? lor aperture illumination. The Taylor aperture illumination is a r 2alizable approximation to  tile Ijolph-Chcbysllev illuminatiot~.~~ It produces a pattern with uniform sidelobes of a  specified value, but only in the vicinity of the main beam. 
 ~Scaling ~Scaling Oscillator :Amplifier L:::.;’;.:circuitTcircuit -nl Tnz I I I I ~-xkw a.Sinusoid bSquarewave c.l-milemarks IIIIIIIIIIII1[I c.l-milemarks (compressed scale)~11111—.—— —.— ___ ___Iulllulllllll d.5.milemarks 11111111111111111111 [11111111 11111 e.20.milem~ks IIIII1I1 fTrigger I I FIG. 1337,—Derivation ofpulses from c-w oscillator. Interruption ofthis current bythesquare wave shock-excites theoscillat- ing circuit. 
 The positive part of this spectrum corresponds to the  complex envelope, which needs to be translated into the digital I and Q representation.  This filter output becomes the input to the A/D converter operating at a sampling rate  of fAD. The spectrum of the A/D converter output is again shown, and it is obtained  simply by replicating the original IF spectrum from minus infinity to plus infinity with  a period of fAD. 
 (Considerably as used here can be precisely de- fined for specific radars, but a general definition would be lengthy and not very useful.) It also implies that the only radar-frequency electromagnetic waves de- tectable within this region, other than those emanating from the radar itself, are from natural thermal and quasi-thermal noise sources, as described in Sec. 2.5. Although this condition is never fully realized, it is approximated for some ra- dar situations. 
 Peak quantization sidelobe values are derived  by Miller78 considering the actual aperture phase distribution. Figure 13.22 shows this  distribution for some scan angle q0 and the resulting errors due to phase quantization.  Although a continuous curve has been drawn, only points corresponding to integral  values of M are meaningful. 
  K(Z  
 p. 86, 1958.  63. 
 CLUTTER 
 Weareconcerned inthis section with theproblem ofimproving theindicator inthis respect. The older PPI radars, both airborne and shipborne, were designed to display targets attheir bearings relative tothe heading ofthe vehicle. More recent design allows adisplay oftargets intheir true bearings, that is,with north atthe top ofthe screen regardless ofheading. 
 CATION OF TRANSISTORS ARE CONSIDERED TO BE THOSE MATERIALS THAT ARE TYPICALLY NEITHER CONDUCTORS NOR INSULATORS 4HE CHARGE CARRYING PROPERTIES OF THESE SEMICONDUCTING MATERIALS CAN BE MODIFIED DRAMATICALLY THROUGH THE SUBSTITUTION OF MINUTE AMOUNTS OF IMPURITY IONS OR THROUGH CRYSTAL LATTICE DEFECTS  EITHER OF WHICH ACT TO MODULATE THE FLOW OF ELECTRONS 3EMICONDUCTOR MATERIALS FROM WHICH TRANSISTORS ARE FABRICATED FOR USE IN SOLID 
 E. Passarelli, Jr., “Gaussian model adaptive processing (GMAP) for improved  ground clutter cancellation and moment calculation,” in 3rd European Conf. on Radar Meteoro. 
     4HE &OURIER 
 TO 
 SQUARE PREDICTION ERROR WHEN  THE RANDOM PROCESSES ARE GAUSSIAN 4HE +ALMAN FILTER CAN BE FORMULATED FOR TARGET MOTION  IN ONE  TWO  OR THREE DIMENSIONS IN POLAR  #ARTESIAN  OR %ARTH 
 The reflectivity, mean doppler velocity, and spectrum width can all be estimated dig- itally from the floating-point linear channel samples. 23.5 OPERATIONAL APPLICATIONS As has been demonstrated, meteorological radars measure backscattered power and radial velocity parameters. The challenge to the radar meteorolo- . 
 TION  BECAUSE THEY ARE COHERENT AND DO NOT USE AMPLITUDE OR SQUARE 
 AVERAGING #&!2 4HE LETTER # INDICATES A COMPARISON FROM ' 6 4RUNK  4!",%  #&!2 ,OSS FOR 0FA    
 the optirnurn weights based on the above criterion are the same as the binomial  weights, when the clutter spectrum is represented by a gaussian f~nction.~ The difference  between a tratisversal filter with optimal weights and one with binomial weights for a three-  pulse cariceler (two delay lines) is less than 2 dB.4.5 The difference is also small for higher-  order cancelers. Tlius the improvement obtained with optimal weights as compared with  binoniial weigl~ts is relatively small. This applies over a wide range of clutter spectral widths. 
 Exposure of the  whole body will cause the internal temperature to rise and produce fever. An increase in  the total body temperature of 1 °C is considered excessive,64 and prolonged exposure or too  high a temperature rise can be fatal. Discomfort resulting from a general rise in body tempera­ ture can be perceived by the victim and serve as a warning. 
 Thisissometimes calledamixer-mairix feed. Aconvenient method forachieving two-dimensional scanning istolisefrequency scanin oneangularcoordinate andphaseshifterstoscanintheorthogonal angularcoordinate, aswas diagrammed inFig.8.18.Thisisanexample ofaparallel-series feed.Itmaybeconsidered asa number offrequency-scanned lineararraysplacedsidebyside. Whenthepowersplitters arefour-port hybridjunctions, ortheequivalent, thefeedissaid tobematched. 
 163. Sensors 2018 ,18, 3750 Figure 4. 3-D Imaging results of near-ﬁeld InISAR. 
 K.: Low-Angle Radar Tracking, Proc. IEEE, vol. 62, pp. 
 Plane ofBeam IIfallsback 45°from Beam I.Ground edges ofboth beams arecommon atK. 2.Asboth beams rotate tozether, target Tispicked UPinBeam Iwhen ground edges of both beams areatK. – 3.Target Tislater picked upinBeam Hwhen ground edges ofboth beams areatK’. 
 Per Eq. 17.8, the crossrange resolution (peak-to-first null) of a SAR is finer  by a factor of two than the resolution for a RAR of equal aperture. An intuitive explanation  for this interesting result is that for RAR, the echo received at a particular aperture location  results from energy transmitted from all locations  in the aperture, whereas for SAR, the  echo received at a particular aperture location results from energy transmitted from that  (known) location  in the aperture; i.e., more information is received (Carrara et al.,3 p. 
 T echnol. 2006 ,21, 98–100. 45. 
 Figure 16.11 shows, inmore detail than Fig. 16.8, thearrangement of the cancellation circuits. The video signals from the JITI receiver amplitude-modulate a15-hlc/sec oscillator and amplifier ofconventional television design. 
 W.: Automatic Detection Theory, chap. 15 of" Radar Handbook," M. I. 
 Surface-based radars derive the height of a target from the range (time) of the echo return and elevation coordinate measurements. A radar on a ship, aircraft, or space satellite may be required to convert tricoordinate measurements relative to the antenna to an inertial reference system as part of the height calculation. The accurate calculation of height from radar measurements must provide for such effects as the location and orientation of the radar antenna in the desired refer- ence coordinate system, the curvature of the earth, the refractive properties of the atmosphere, and the reflective nature of the earth's surface. 
 BEAM OR SIDELOBE CLUTTER &ORWARD 
 BEAM CLUTTER POWER SPECTRAL DENSITY CAN BE  MODELED WITH A GAUSSIAN SHAPE WITH A STANDARD DEVIATION RC   $F -AIN 
 On the other hand,  there are major advantages to be had, such as simultaneous reception of several  radar signals on different frequencies, so a single receiver can service more than  one radar transmitter. Calibration.  The conventional beamforming process in an ideal multi-channel  receiving system should deliver a single output, assigned to the correct direction, for a  plane wave incident on the antenna array. 
 His formula for the above parameters yields a value of -117 dBm for the corre- lated noise power from the clutter. This is for the extreme case of a single an- tenna at exact ground level looking into very severe clutter (0.1 m2/m2). A more practical way to look at the problem is to note that clutter from very short ranges and spillover are almost equivalent phenomena. 
 PLAY UNIT 4HE WHEELS DRIVE A SHAFT ENCODER THAT TRIGGERS DATA ACQUISITION AND HENCE THE DISPLAY THAT IS SYNCHRONISED TO THE MOVEMENT OF THE SYSTEM !N EXAMPLE OF THE DISPLAY  #HAPTER . Ó£°Ó  2!$!2 (!.$"//+  WHICH TAKES THE FORM OF A  CROSS SECTION OF THE GROUND SURVEYED  BY THE '02  IS SHOWN  IN &IGURE  4HE HORIZONTAL SCALE IS  CM PER MARKER AND THE VERTICAL SCALE IS TIME  IN NANOSECONDS  NS  !N EXPLANATION OF THE IMAGE IS PROVIDED LATER IN THIS CHAPTER '02 SYSTEM DESIGN CAN BE CLASSIFIED INTO TWO GROUPS '02 SYSTEMS THAT TRANSMIT AN  IMPULSE AND RECEIVE THE REFLECTED SIGNAL FROM THE  TARGET USING A SAMPLING RECEIVER CAN  BE CONSIDERED TO OPERATE IN THE TIME DOMAIN '02 SYSTEMS THAT TRANSMIT INDIVIDUAL FRE 
 Although the detection decision is usually based on measurements at the video output, it is  easier to consider maximizing the signal-to-noise ratio at the output of the IF amplifier rather  than in the video. The receiver may be considered linear up to the output of the IF. It is shown  by Van Vleck and Middleton3 that maximizing the signal-to-noise ratio at the output of the IF  is equivalent to maximizing the video output. 
  
 The block diagram of this type of  MTI canceler is shown in Figure 2.33. Figure 2.34 to Figure 2.36 represent typical velocity response curves obtainable from  one-, two-, and three-delay cancelers. Shown also are the canceler configurations assumed,  with corresponding Z-plane pole-zero diagrams. 
   3ESS 7! 
 224--227, March, 1966.  102. Riley. 
 Radar equation for SAU. Eacli particular application has its own form of the radar equation.  7'1ic SAR 1i;ls a ~~nrticularly iritercsting form, especially when the relationships derived above  arc ti\k~11 into ;ICCOIII~(. 
 Performance Comparisons.  Given the number of STAP architectures and cor - responding radar system design solutions, general STAP performance comparisons are  difficult to come by. In general, STAP provides a robust solution to deal with clutter  and jamming interference and helps alleviate hardware mismatch effects within rea - son (amplitude and phase adjustments are applied to antenna element and time dis - placed returns). 
 Land clutter has been modeled as a Lambert surface with <1° varying as sin2 <j,, where  <j, = grazing angle55; as assemblies or spheres, hemispheres, hemicylinders55•56; as specular  renection from small Oat-plate segments, or facets, which backscatter radar energy only when  the facets are oriented perpendicular to the radar line of sight57; as a slightly rough surface  (similar to the model used to describe sea clutter) to describe scattering from concrete and  asphalt40; as an application of the Kirchhoff. Huygens principle which makes the assumption  that the current flowing at each point in a locally curved surface is the same as would flow in  the surface ir it were flat and oriented tangent to the actual surface58; and as a model consist­ ing of long, thin, lossy cylinders randomly distributed to describe certain types of vegetation  such as grass, weeds, and flags.40 None or these have been too successful as a general model;  however, they do provide some guidance for the understanding of specific land clutter. 35  13.6 DETECTION OF TARGETS IN LAND CLUTTER  Many of the techniques discussed in Sec. 
 THE 
 Meastiring the range at which the target is first seen on the bottom lobe, or the range  where it disappears because of the first null of the lobing pattern, can be related to the target  height. This effect is more applicable at the lower microwave frequencies and for radars sited  ovcr water. At the higher frequencies where the lobes are narrow, a coirnt of the lobes pzr unit  distance can be related to the target height. 
 A. Ecker, and R. A. 
 INFLICTED PERFORMANCE LIMITATIONS  !TTEMPTS TO REDUCE CONTAMINATION FROM EXTERNAL BROADCAST SIGNALS BY INSERTING NAR 
 QUENCY ALLOCATION TO MAKE USE OF THE HIGHER RANGE RESOLUTION IS NOT AN ISSUE 3HORT  $WELL  4IME  3PECTRA  -AXIMUM  %NTROPY   3PECTRAL PROCESSING OF  WEATHER ECHOES ADDS ANOTHER DEGREE OF FREEDOM THE FREQUENCY DIMENSION  TO THE ABIL 
 Proper convergence of the field solution and resulting patterns is a function of  the grid size, and this is generally achieved and verified by incrementally decreasing the  grid size until the solution stabilizes. Achieving sufficient convergence in reflector PO  computations within reasonable computer run times (a few minutes or less) is rarely a  problem with modern computers. Geometrical Optics (GO) Reflector Analysis, Including GTD/UTD. 
 Weneed notconcern ourselves here with these complications, which are adequately treated inVol. 13. Methods have been worked outforrapidly calculating thefield strength over acurved reflecting earth. 
 Rec ., 1975, pp. 170–175. 47. 
 Thewindhasheenassumed heretoheadriving forceindetermining theradarback­ scatterfromthesea.Itisindeed,huttherelation between thewindandtheseaconditions is complex; hence,sowillbetherelation between the'windandtheradarbackscatter. The capillary wavesandtheshortgravitywavesbuildupquickly withthewindsothat'the value of(10measured withradarsatthehighermicrowave frequencies shouldbequiteresponsive to windconditions. Thelongergravity wavesrequire afinitetimetobuildupandreach saturation: hence,thewindalonemightnotbeatruemeasure ofseaconditions unlessaccount istakenofthelengthoftimeandthedistance (fetch)overwhicilthewindhasbeenblowing. 
 Here, ho~rever, itispossible tousc a FIG. S.S,—Interrogation ofabeacon byside lobes. Interrogation ofasbipborne 10-cm beacon byaradar seton\ft.Cadillac onMt.Desert Island, }Ie, (a)shows the extended pattern atabout 4o’clock inthepicture; (b)shows howitranhered”red tothe reply inthemain beam bymanipulation ofthegaincontrol oft’~crereiver ofthebeacon signals. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°x £n°ÈÊ , ,Ê-"1 
 10. A. Freeman, M. 
 Return from Two Isotropic Targets.—The outstanding features ofthe signal returned from complex targets—its fluctuations and its wavelength dependence-can bestudied byconsidering asimple model consisting oftwo equal isotropic targets adistance 1apart. This distance isassumed tobesmaller than c7/2, where ~isthepulse duration, sothat the signals overla~at least partly. The ratio ofthe received power from the two targets tothat which would bereceived from one ofthe targets alone (atadistance large compared with 1)isgiven by g=1,%+3””’)+.%(’-;””’’)12 “COS2(+’)‘++4+’)1 ’23). 
 oritmaybeinterpreted astheratiooftheactualavailable outputnoisepowertothcnoise powerwhichwouldbeavailable ifthenetwork merelyamplified thethermal noise.The noisefiguremayalsobewritten F=kToBnG+liN=1+liN nkToBnG kToBnG whereI1Nistheadditional noiseintroduced bythenetwork itself. Thenoisefigureiscommonly expressed indecibels, thatis,10logFn'Thetermnoise factorisalsousedanimes insteadofnoisefigure.Thetwotermsarenowsynonymous.. HtiC'l:IVERS, LIISI'LAYS, AND DUPLEXERS 345  The definition of noise figure assumes the input and output of the network are matched. 
 ORDER SPATIALLY BASED HARDWARE REQUIREMENTS !S ILLUSTRATED IN &IGURE   PLATFORM MOTION COMPENSATION RESULTS IN DIFFERENT APERTURE WEIGHTING FOR SUCCESSIVE PULSES IN A 34!0 SOLUTION !LTHOUGH GENERALLY SPEAKING  WELL 
 5. Rödelsperger, S. Real-Time Processing of Ground Based Synthetic Aperture Radar (GB-SAR) Measurements ; (No. 
 IEEE T rans. Geosci. Remote Sens. 
 54 It is not often used, however, because of its higher loss, lower peak power, and  higher cost as compared with digitally switched diode phase shifters. Ferroelectric phase  shifters. in which the dielectric of a ferroelectric material is a function of the applied electric  field. 
 To ensure that no grating lobes enter real space, the element spacing must be . (b) FIG. 7.10 Grating-lobe positions for (a) rectangular and (b) triangular grids, showing the motion of the lobes as the beam is scanned an angle 60.(a)COS OTy UNITCIRCLE cos a x sin 90- COS Oy UNIT CIRCLE COS Ox sin BO . 
 NOISE RATIO #OST IS THUS REDUCED BY EMPLOYING A SMALL RECEIVING ANTENNA ELEMENT (EIGHTS OF n M ARE COMMON 4HE LOOK 
 WEIGHT CANCELER . Ó°ÓÈ  2!$!2 (!.$"//+  SUBSEQUENTLY IMPLEMENT THE CORRESPONDING OPTIMUM FILTER !N EXAMPLE OF SUCH AN  ADAPTIVE -4) SYSTEM IS DISCUSSED IN 3ECTION  &OR A SINGLE RADAR PULSE WITH A DURATION OF A FEW MICROSECONDS  THE DOPPLER SHIFT  DUE TO AIRCRAFT TARGET MOTION IS A SMALL FRACTION OF THE SIGNAL BANDWIDTH  AND CONVEN 
 STATE ACTIVE APERTURE PHASED ARRAY RADAR THAT WAS BUILT FOR THE  %LECTRONIC 3YSTEMS $IVISION OF THE 53 !IR &ORCE BY THE %QUIPMENT $IVISION OF THE  2AYTHEON #OMPANY DURING THE LATE S 4HE RADAR IS A LONG 
 As with any CFAR,  the constant false-alarm rate is maintained at the expense of the probability of detection. With  log-FTC there is no improvement in target-to-clutter ratio and there is no subclutter visibility.  The log-FTC, or similar CFAR, is necessary, however, in order to extract the target informa-  tion contained in the radar signal that otherwise would be undetected if displayed along with  the clutter, or which would be lost because of computer overload in an automatic system. 
 E. Miller, and M. T. 
 precision in the itidividual parameters of the radar equation. Nevertheless, if a.particular range  is required of a radar, the systems engineer must provide it. The safest means to achieving a  specified range performance is to design conservatively and add a safety factor. 
 Several other analytical probability density functions that  lie between these two extremes have been suggested for modeling the actual statistical  RADAR CLUTIER 479 Log--normo!o5~-"----'---T--'-1 ~----.,---,-----.-----r---''---''----' 04 03 02 0001 0L..-.-..L 2--4L--.-L---L.-----l--L---'-----,-L--:",----,,-L---"22oIII III U III.0o 0'Ol-c iii0054.1u)( 4.1OO? o >-001 1i0005o ~0002 a..0001 0005 Fi~Uf{'13.5Experimental statistics orvertical polarization, X-bandseaclutterrortwoseastates.Pulse width=20ns,beamwidth =0.5°,grazing angle=4.7°,range=2nmi.TheRayleigh distribution is shownrorcomparison. Dashed curveshowsattempt tofittheseastate2-3datatolog-normal distrihu­ tion.(AlierTrullk (lIldGeorge. '2) customary waybasedongaussian noise,Toavoidfalsealarms,thethreshold detector atthe outputofsuchareceiver mustbesettoahighervaluethanwhentheclutterisRayleigh. 
 Ifthefirstblindspeedwere600knots,themaximum unambiguous rangewouldbe130nautical milesatafrequency of300MHz(UHF), 13nautical milesat 3000MHz(5band),and4nautical milesat10,000MHz(Xband).Sincecommercial jet aircrafthavespeedsoftheorderof600knots,andmilitary aircraftevenhigher,blindspeedsin theMTIradarcanbeaseriouslimitation, ." Inpractice, long-range MTIradarsthatoperateintheregionofLor5bandorhigherand areprimarily designed forthedetection ofaircraft mustusuallyoperate withambiguous dopplerandblindspeedsiftheyaretooperatewithunambiguous range.Thepresence ofblind speedswithinthedoppler-frequency bandreducesthedetection capabilities oftheradar.Blind speedscansometimes betradedforambiguous range,sothatinsystems applications which requiregoodMTIperformance, thefirstblindspeedmightbeplacedoutside therangeof expected doppler frequencies ifambiguous rangecanbetolerated. (Pulse-doppler radars usuallyoperate inthismanner). As.willbedescribed later,theeffectofblindspeedscanbe significantly reduced, without incurring rangeambiguities, byoperating withmorethanone pulserepetition frequency. 
 Residual Motion Error Correction with Backprojection Multisquint Algorithm for Airborne Synthetic Aperture Radar Interferometry. Sensors 2019 ,19, 2342. [ CrossRef ][PubMed ] 5. 
 3 )NT 3YMP $IG  PP n  *UNE   % 0 %KELMAN AND " 3 ,EE  h!N ARRAY 
 3.5b).  Practical receivers can only approximate this characteristic. (Note that this is the same as the  spectrum of a pulse of sine wave, the only difference being the relative value of the duration <5.)  In many instances, the echo is not a pure sine wave of finite duration but is perturbed by  fluctuations in cross section, target accelerations, scanning fluctuations, etc., which tend to . 
 [CrossRef ] 22. Meyer, F.J. A review of ionospheric effects in low-frequency SAR–Signals, correction methods,and performance requirements. 
 Asimilartechnique41.51utilizes sum(I:)anddiITerence (L\)patterns whoseratioAq;:cjssymmetrical. Justasinoff-axistracking, the<i-iltenna boresight· islockedatsomeelevation angle.Thisresultsinthelowerofthetwo peaksofthesymmetrical L\/r.ratiobeingplacedinthedirection ofthebisectorofthetarget andimage.Underthiscondition, thevaluesofL\/r.inthedirection ofthetargetanditsimage areequal.Theestimate oft~r&etel~vaUQt\ isunaffected bythephaseandamplitude ofthe image.(Theangleofthetarget/image bisector isapproximately givenbytheratiooftheradar antenna-height-to-target-range.). The normal monopulse radar receiver uses only the in-phase (or the out-of-phase) com-  ponent of the difference signal. 
 One consisted ofattempts toimprove and modify conventional types oftransmitting tubes, and the other ofefforts to devise entirely new forms oftransmitting tubes. Modifying the conventional type oftransmitting tube tosatisfy the requirements ofradar met with difficulties. Toafirst approximation theelectronic characteristics ofalow-frequency oscillator oramplifier are preserved athigh frequency only ifalldimensions ofthetube arescaled inproportion tothewavelength A;asaresult, itisnecessary toreduce the size oftubes asthe frequency isincreased. 
 A  comparison of the two definitions is given by Hollis.12 Marcum's definition of false-alarnl time  is seldom used, although his definition of false-alarm number is often found.  The solid straight line plotted in Fig. 2.8~ represents a perfect predetection integrator  with E,(n) = 1. 
 A uniformly illuminated aperture and beam and a uniform half-aperture dif- ference beam are used for comparison of the three implementations. In a radar which employs vector monopulse processing for height finding, it is possible to coherently precombine the returns from multiple pulses or subpulses in the simultaneous beams to form a single estimate of the target elevation angle of arrival, as suggested in Fig. 20.7. 
 Mooney: The Development of Airborne Pulse Doppler Radar, IEEE Trans., vol. AES-20, pp. 290-303, May 1984. 
 It is desirable to eliminate blind phases in any )  MTI processor. but it is seldom done with analog delay-line cancelers because of the complex- - ity of the added analog delay lines of the second channel. The convenience of digital processing  allows the quadrature channel to be added without significant burden so that it is often  included in digital processing systems. 
 Change Detection in SAR Images Based on Deep Semi-NMF and SVD Networks. Remote Sens. 2017 ,9, 435. 
 J. Anderson, “Remote sensing with the Jindalee Skywave Radar,” IEEE J. Ocean. 
 Theyseemtobemoredetectable withradarhavingamoderate resolution ratherthanahigh resolution.66. 482 INTRODUCTION TO RADAR SYSTEMS  The backscatter from ice at high grazing angles is complicated by the relative ease of  penetration of radar energy into the ice. The reflection from the air-ice interface may be  accompanied by a reflection from the underlying ice-water or ice-land interface. 
 Ó{°£Ó  2!$!2 (!.$"//+  "Y SUITABLE CHOICE OF THE ANTENNA GAINS  ONE MAY DISTINGUISH SIGNALS ENTERING THE  SIDELOBES FROM THOSE ENTERING THE MAIN BEAM  AND THE FORMER MAY BE SUPPRESSED &IGURE A ILLUSTRATES THE RADIATION PATTERN OF THE MAIN ANTENNA TOGETHER WITH A  LOW 
 Since the transmitted frequency is not usually a multiple of the reciprocal of the subpulse width, the coded signal is generally discontinuous at the phase-reversal points. FIG. 10.8 Binary phase-coded signal. 
 In Farina and Lombardo,170 the performance of such a tech - nique is evaluated in terms of SAR impulse response, detection performance of  point target, and radiometric resolution of an extended scene. In Ender171 a SAR  image, taken with an experimental four-channel SAR jammed by a small 1 watt  ch24.indd   50 12/19/07   6:01:12 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 In this section, these basic reflector design  principles are reviewed via use of a canonical example. Consider a parabolic-shaped reflector forming a circular aperture, fed by a horn at  a central focal point. This simple reflector configuration has a surface shape defined  by the equation  zx y ff =+−2 2 4 (12.1) where f is the focal length and the vertex is located at z = −f. 
 Equation (10.26) forms the basis of the technique used by Woodward and Davies for the  analysis of radar reception problems when the interference is caused by white gaussian noise.  Except for the a priori weighting factor p(SN), Eq. (10.26) shows that the most probable  waveform si(t) is the one which has the least-mean-square deviation from the received  waveform y(t). 
 Electronic tuning is also p~ssible.~'  6.3 KLYSTRON AMPLIFIER .  The klystron amplifier is an example of a linear beam tube, or 0-type tube. The characteristic  feature of a linear beam tube is that the electrons emitted from the cathode are formed into a  long cylindrical beam which receives the full potential energy of the electric field before tllt:  beam enters the RF interaction region. 
 To study the effect of the noise on the result of aspect entropy, we use the models mentioned in Section 2. Varying levels of noise are added into the RCS curve for the three anisotropic models: dihedral A, dihedral B, and the trihedral. The SNR ranges from 10 dB to 40 dB. 
 558 INTRODUCTION TO RADAR SYSTEMS  target dirnensi~n.~' If a bistatic radar can be designed to take advantage of the large forward-  scatter cross section, a significant improvement in detection capability can be had, or for the  same detection capability as a radar with b # 180°, less power need be radiated. However,  the radar applications in which-ad-vantage can be taken of the large forward-scatter signal are  limited. The scattering angle must be exactly, or reasonably close to, 180' in order to obtain  forward scatter. 
   -4) 2!$!2  Ó°£ä£  & % .ATHANSON AND * 0 2EILLY  h2ADAR PRECIPITATION ECHOES%XPERIMENTS ON TEMPORAL  SPATIAL   AND FREQUENCY CORRELATION v 4HE *OHNS (OPKINS 5NIVERSITY  !PPLIED 4ECHNOLOGY ,ABORATORY   2EPORT .O 4ECH -EMO 4' 
 MENT FACTOR FOR THE TRIPLE 
 Tlie electron gun consists of the cathode.  ~nodirl;ititig arioclc or coritrol grid. and tlie anode. 
 Moving-Target Surfaces. Sometimes clutter has internal motion. This can occur when fixed radars are used to observe movement of the sea and the land. 
 Ifthe drop perregulator 115V junction exceeds 1to2volts,Rect.Alternator 4oocps sparking may occur which will fieldPs ruin thepile. Under changing load condi- FIG. 14,13.—Schematic diagram of tions, the regulator acts toin- s~abilizing transformer involtage regulator cmcuit of400-cps aircraft inverter,crease orreduce thefield current: asinany action ofthis kind, hunting may result. 
   PP n  -ARCH   ' - $ILLARD  h! MOVING 
 Hildebrand and Mueller4 and Mueller and Hildebrand5 have quantitatively demonstrated that it is possible for an airborne meteorological doppler radar to measure internal kinematic fields that are comparable to those obtained from ground-based systems. This powerful technique permits the use of a mobile platform, which therefore allows measurements over regions not accessible by ground-based systems. Moreover, the mobility of the aircraft permits longer-term observations of rapidly moving but long-lived storms and cloud systems. 
 Pressurization hasadvantages and disadvantages. Among thelatter areinconvenience resulting from inaccessibility yofparts foradjustment and repair, and difficult yoftransferring heat through the pressure wall. The r-fhead ofasmall airborne setwill undoubtedly beacompletely pressurized unit. 
 Any use is subject to the Terms of Use as given at the website. Radar Cross Section.  RADAR CROSS SECTION  14.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 The single-reflector design shown in Figure 14.23 worked tolerably well for small  test targets, but it soon became apparent that the reflector had to be considerably larger  for many targets of vital military interest. This could be accomplished by doubling or  tripling the size of the reflector, but that brought on a round of other problems, mainly  the increased focal length of the reflector. 
 L., and G. W. Hay don: Predicting Statistical Performance Indexes for High Frequency Telecommunications Systems, ESSA Tech. 
 In the analysis, some conditions are stated for which the terms affecting range resolution can be factored from the elements affecting azimuth resolution, so that the resulting ambiguity function can be written as the product of two factors, one for range and one for azimuth. Role of the Generalized Ambiguity Function. In this subsection, a definition of a generalized ambiguity function will be given, and its role in determining the resolution of a system will be interpreted. 
 ANGLE RADAR TRACKING v 0ROC )%%%  VOL   PP n  *UNE   $ + "ARTON   2ADAR 2ESOLUTION AND -ULTIPATH %FFECTS  IN VOL  OF  2ADARS  .ORWOOD  -! !RTECH  (OUSE    $ $ (OWARD  * .ESSMITH  AND 3 - 3HERMAN  h-ONOPULSE TRACKING ERROR DUE TO MULTIPATH  #AUSES AND REMEDIES v IN %!3#/. 2EC   PP n  % - 4 *ONES  h0ARABOLOID REFLECTOR AND HYPERBOLOID LENS ANTENNA v  )2% 4RANS  VOL !0 
 14-23, March, 1965.  66. McCaskill, T. 
 ERROR REGION OF THE ANTENNA PATTERNS AND EVENTUALLY REACH THE POINT OF RESOLUTION OF ONE  OF THE AIRCRAFT 4HE RESULTANT ANGLE 
 POINT TARGETS AND RETURNS FROM EXTENDED TARGETS )T IS SIGNIFICANT THAT THE  EXTENDED TARGETS ARE NO LONGER VERY EXTENDED 4HE FACE OF A MOUNTAIN AT  MI FROM  TO  OCLOCK IS ONLY A LINE )F THE -4) SYSTEM WERE INCAPABLE OF DISPLAYING AN AIR 
   4(% 02/0!'!4)/. &!#4/2  &0  ). 4(% 2!$!2 %15!4)/.   ÓÈ°x ANGLE WITH THE SURFACE EQUAL  TO THAT OF THE INCIDENT WAVE  AS SHOWN IN &IGURE  4HE  STRENGTH  OF  THE  REFLECTED WAVE IS DETERMINED BY THE REFLECTION COEFFICIENT  A VALUE THAT DEPENDS UPON THE FREQUENCY AND POLARIZATION OF RADIATION  THE ANGLE OF INCIDENCE  AND THE ROUGHNESS OF THE REFLECTING SURFACE &OR  SHALLOW  INCIDENCE  ANGLES AND SMOOTH SEAS  TYPI 
 STATE TRACKING GAINS AS A FUNCTION OF  FTRACK /NE CAN SEE THAT  LARGE ASSUMED MANEUVERS LARGE  Q  @A  OR A  LARGER TIME BETWEEN UPDATES   4 OR VERY  ACCURATE RADAR MEASUREMENTS SMALL    WILL RESULT IN LARGE TRACKING GAINS 4HE POSI 
 T. Rusch, “Scattering from a hyperboloidal reflector in a cassegrain feed system,” IEEE  Trans ., vol. AP-11, pp. 
 Dorr: 3-D Radar Based on Phase-in-Space Principle.  IEEE,Trans .• vol. /\ES-2. 
 -(Z PULSES IN ONE OF FOUR BANDS CENTERED ON THE FREQUENCIES CITED IN 4ABLE   -ARS %XPRESS IS IN AN ELLIPTICAL ORBIT SUBSURFACE SOUNDING OPERATIONS  ARE RESTRICTED TO THE LOWER  KM TO  KM ALTITUDES 3OUNDING IS FURTHER LIMITED BY THE IONOSPHERE  WHICH PREVENTS EFFECTIVE RADIO WAVE PROPAGATION TO THE SURFACE AT FREQUENCIES BELOW THE PLASMA FREQUENCY  F   WHICH AT -ARS IS  ^ -(Z ON THE SUNLIT SIDE  AND ^ -(Z ON THE DARK SIDE 4HE IONOSPHERE INDUCES A FREQUENCY 
 A-Sandwich . A commonly used radome-wall cross section is the A-sandwich,  which consists of two relatively dense thin skins and a thicker low-density core. This  configuration exhibits high strength-to-weight ratios. 
 QUENCIES IN A SEQUENTIAL MANNER AND RECEIVE THE REFLECTED SIGNAL FROM THE TARGET USING A FREQUENCY CONVERSION RECEIVER CAN BE CONSIDERED TO OPERATE IN THE FREQUENCY DOMAIN 4HE FIRST USE OF ELECTROMAGNETIC SIGNALS TO DETERMINE THE PRESENCE OF REMOTE TERRES 
   #OSINE SQUARE ON  D" PEDESTAL  
 SCATTEROMETER 
 S. Raven, and P. Waterman, Airborne Radar , Princeton, NJ: D. 
 855-863, May, 1959.  30. Dunn, J. 
 Ground Airborne Multistage Radar, pp. 7/1-7/3, London, 1981. 132. 
 This allows the system to be  optimized at the range and angular sector where the target is located. MTI is also used  to detect moving ground vehicles by reconnaissance and tactical fighter aircraft. The environment of high platform altitude, mobility, and speed, coupled with  restrictions on size, weight, and power consumption, present a unique set of problems  to the designer of airborne MTI systems. 
 Means were developed forreproducing radar indications atapoint distant from thesetthat gathered theoriginal data; theintelli- gence necessary was transmitted from theradar tothedistant indicator byradio means. This radar relay, asithascome tobecalled, isdescribed insome detail inChap. 17. 
 NING HITS PER BEAMWIDTH &OR REFERENCE  THE MEAN OF  ) IS ALSO SHOWN FOR LINEAR PROCESSING  ) REFERS TO THE  IMPROVEMENT FACTOR OF A THREE 
 SDI: The grand experiment,” IEEE Spectrum ,   vol. 23, no. 9, pp. 
  
 WIDTH 4HE SECOND ADVANTAGE OF SHORTER WAVELENGTHS IS THAT EVEN A RELATIVELY SMOOTH SEA  SUCH AS SEA STATE   HAS WAVE HEIGHTS OF MANY WAVELENGTHS AND APPEARS ROUGH  RESULTING IN A SMALLER REFLECTION COEFFICIENT 4HIS IS OBSERVED IN &IGURE  TO GIVE SMALL MULTIPATH ERRORS 4HE  
 BASED RADARS DO NOT MEET USER DEMANDS WHEN OPERATING IN HEAVY SEA AND PRECIPITATION CLUTTER 3MALL CRAFT AND BUOYS BECOME INVISIBLE ON THE DISPLAY  CREATING DANGER TO LIFE )-/ RECOGNIZED THIS PROBLEM AND  IN ORDER NOT TO CON 
 4.34 for a three-pulse delay-line canceler.61•69 There are two  basic methods for providing the doppler frequency compensation. In one implementation the  frequency of the coherent oscillator (coho) is changed to compensate for the shirt in the clutter  doppler frequency. This may be accomplished by mixing the output of the coho with a signal  from a tunable oscillator, the frequency of which is made equal to the clutter doppler. 
 Tuning is not  otherwise usually attempted in magnetrons, although in  one type of equipment there is a tunable magnetron  giving a possible variation of about 75 megacycles either  way (at some 3000 megacycles), and this tuning is  achieved by making the lid of the magnetron itself of  thin metal, so that the centre can be depressed on a  screw-thread and the internal capacity of the segments  varied by a small amount. Experiments have also been  carried out with tunable magnetrons having metal rods  . CENTIMETRIC TECHNIQUE Iit9  capable of being moved in and out of the main anode  block. 
 35–41.  3. T. 
 For example, if the array has been thinned so that only 10% of  the elements are used, the gain of the array will drop by 10 dB. However, because the  main beam is virtually unchanged, about 90% of the power is delivered to the sidelobe  region. Thinned arrays are seldom used. 
 He used an antenna rotating at up to 600 rpm and  a PRF of 5 KHz. This gave two correlated pulses per beamwidth, but the pulses from the  next scan, 0.1 s later, were decorrelated from the former. Crony noted that the rapid scanning of the antenna allowed the eye/brain func - tions of the operator to perform scan-to-scan correlation. 
 RESOLUTION TIME 
 The diodes are used to switch in increments of capacitance and inductance  that provide small changes in phase. Because the diodes are decoupled from the main  transmission line, they need to handle only modest amounts of power in each diode.  Very high power (i.e., kilowatt) configurations are possible. 
 For all practical purposes tlie feed is out of the path of the reflected energy, so that  there is no pattern deterioration due to aperture blocking nor is there any significant amount  of energy intercepted by the feed to produce an impedance mismatch.  It should be rioted that tlie antenna aperture of an offset parabola (or any parabolic  reflector) is the area projected on a plane perpendicular to its axis and is not the surface area.  Tlie offset parabola eliminates two of the major limitations of rear or front feeds. 
 497–503. 70. S. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 4.38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 MRWS can also be implemented with a high-medium PRF, which is characterized  by the waveform’s doppler coverage being unambiguous in doppler magnitude, but  not doppler sense, for the maximum target doppler of interest. 
 MITTING AND RECEIVING SO THAT IN BOTH CASES THE BEAM POINTS IN THE SAME DIRECTION 4HIS METHOD ALLOWS FLEXIBILITY IN OPTIMIZING THE TRANSMITTER APERTURE DISTRIBUTION  PERHAPS FOR MAXIMUM POWER ON THE TARGET  AND SEPARATELY OPTIMIZING THE RECEIVER SUM AND DIFFERENCE PATTERNS FOR LOW SIDELOBES 3INCE A CHANGE IN FEED POSITION CORRESPONDS TO SCANNING WITH TIME DELAY  ADDITIONAL FEEDS MAY BE ADDED TO PROVIDE SEVERAL TIME 
 C'W AND FREQCJENCY-MO1)ULATED RADAR 89  ivliere .I,, J,. J2, etc = Bessel functions of first kind anci order 0, 1, 2, etc., respectively  L) = (Afj'fm) sin 2qJ,Ro/c  Ro = distance to target at time t = 0 (distance that would have been meas-  ured if target were stationary)  c = velocity of propagation  ,fd = 21-, ,/;/C = doppler frequency shift  r., = relative velocity of target with respect to radar  4, = pllase sliift approxirnately equal to angi~lar distance 4cf, R,/c  $,,, = phase shift approxirnately equal to 2nJ,, Role  l'lle difference-freque~icy signal of Eq. (3.16) consists of a doppler-frequency cornpollent  of aniplitude Jo(l)) and a series of cosine waves of frequency f,, 2fm, 3fm, etc. 
 398 INTRODUCTION TO RADAR SYSTEMS  77. Finn, H. M., and R. 
 RECEIVER  RANGE 
 The breakdown takes place across theinner face oftheelongated glass window. Aduplexer that represents inwaveguide the basic scheme ofFig. 11.14 appears inFig. 
   PP n    3 0 'OGINENI AND + *EZEK  h5LTRA 
 ..'".. .'. .Figure,3.4showsablock:~jagra~"oft~c ~Wradar whosereceiveroperates withanonzeroIF. 
 SIBLE SOLUTIONS L 3ELECTION OF THE OPTIMUM OR NEAR OPTIMUM SOLUTION   )N MANY ENGINEERING ENDEAVORS  OPTIMUM DOES NOT MEAN THE BEST SINCE THE BEST  MIGHT NOT BE AFFORDABLE OR ACHIEVABLE IN THE REQUIRED TIME  /PTIMUM  AS USED HERE   MEANS THE BEST UNDER A GIVEN SET OF ASSUMPTIONS %NGINEERING OFTEN INVOLVES ACHIEV 
 Pulse compres - sion techniques are used to reduce the required peak power. Even single Gallium  Nitride devices can generate hundreds of watts of peak power, at mean powers easily  sufficient for CMR applications. Also, advances in digitally controlled waveform  generators have given designers the ability to create pulse-compressed waveforms  with high precision and at low cost. 
 CLUTTER CROSS 
 5.19 describes the measured bounds of the lowest servo resonant  frequency as a function of antenna size achieved with actual tracking radars.  N 10  I  I  ;.­ (.)  C:  Q) :,  0  Q) ...  c  0  C:  ~  Q)  a:: 1 0 Estimated  " //),. 
 , vol. 94, pp. 9183–9191, 1989. 
 An integrator based on the tapped delay line is shown in  Fig. 10.9. The time delay through the line is made equal to the total integration time, and the  taps are spaced at intervals equal to the pulse-repetition period. 
 E.: First-Order Theory and Analysis of MF/HF/VHF Scatter from the Sea, IEEE Trans..  vol. AP-20. 
 POINTING DIRECTION AND INTERPULSE MOTION NORMALIZED TO THE INTERPULSE MOTION USED TO DESIGN THE COMPENSATION PATTERN  #ANCELLATION RATIO IS DEFINED AS THE  RATIO OF INPUT CLUTTER POWER TO OUTPUT CLUTTER RESIDUE POWER  4HE PEAK ON THE  AXIS IS TYPICAL OF THE OPTIMIZED $0#! PERFORMANCE ILLUSTRATED IN &IGURE  Î°Ê -* 
 TIONS IN AN ATTEMPT TO IMPROVE THE  DETECTION OF TARGETS IN HEAVY SEA CLUTTER CONDITIONS  #HAPTER  o  ! LIST OF ALL USED MARITIME ABBREVIATIONS IS INCLUDED AT THE END OF THE CHAPTER. 
 Steer, “State-of-the-art W-band extended interaction klystron for  the CloudSat program,” IEEE Transactions on Electron Devices , vol. 52, pp. 895–898, 2005. 
 Summer shows much greater losses than other seasons. 2. Except for summer, night losses are only slightly less than day losses. 
 The pulse compression ratio is also equal to the product of the time duration and the spectral bandwidth (time- bandwidth product) of the transmitted signal. A pulse compression radar is a practical implementation of a matched-filter system. The coded signal may be represented either as a frequency response H(U) or as an impulse time response h(i) of a coding filter. 
 RECEIVERS, DISPLAYS, AND DUPLEXERS 359  back of the tube phosphor, or it can be used to photograph the display without interfering  with the operator. The CRT phosphordoubles as art optical and an electronic screen to give  the operator a mixed presentation viewed in the usual manner from the front.  Synthetic-video Displa)·s.26·35·36 The use of a digital computer, as in an automatic detection  and tracking processor. 
 25, pp. 592-593, Dec. 13, 1973. 
 The maximummeasurable range of a radar set depends upon the peak power in relation tothe pulse repetition rate. Assuming sufﬁcient power is radiated, themaximum range at which echoes can be received may be increased throughlowering the pulse repetition rate to provide more time between transmittedpulses. The PRR must be high enough so that sufﬁcient pulses hit the targetand enough are returned to detect the target. 
 "'  OJ  OJ '- 2  <lJ  >  a  ti.J '- "O  "' l.L 50 ····---r- 2.0  t.O  0.5  0.2  0.1 -·  0.05 {  %  ......  0.02 · i:  <:::,  ,<:;:  b  0.01 ·":!  ~ 'l.)  12  0.005 <:::,  ~  0.002 '>-.=0  0.00 I __ _j_ ____ ...L... _ __j ____ ____j _____ ~~-~--~  30 40 50 60 70  Distance, km 80 90 100  Figure 12.7 Theoretical field strength (relative to free-space field strength) as a function of the distance  from the transmitting antenna. 
 The  effective length of the synthetic aperture can be limited by the stability of the transmitter or the  receiver.  The heart of the SAR is the processor which must provide the proper amplitude and phase  weights to the stored pulses, and sum them !O obtain the image of the scene. Optical processors  and digital processors have both been used. 
 57. A. Bernard, private communication, MIT Lincoln Laboratory, July 24, 2006. 
 The time separation between the echoes received in  the vertical and slant beams is a measure of the target height. A short time-separation signifies  low altitude, while longer separations occur with high altitude targets. Two separate rdkctors  may be used to generate the twoJan beams, 30 the two reflectors might be back to back, a single  reflector with two feeds can: be used.~h36 or the two beams can be generated with a single  phased array antenna., The. 
 Palermo, and L. J. Porcello: Optical Data Processing and Filtering  Systems, pp. 
 4.10. The finite width of the clutter spectrum is also  shown in this figure so as to illustrate the additional cancellation of clutter offered by the  double canceler.  The two-delay-line configuration of Fig. 
 For the suppression of very strongly cross -talking transmission pulses into  the receiving system, the receiver input is short -circuited or decoupled by a circulator.  Figure  8.4 shows a typical, simple pulse Radar syste m.  To produce the pulses either magnetrons or  switched amplifiers are employed. 
 BETA TRACKER OR OTHER FILTERING TECHNIQUE IS USED TO SMOOTH MEASUREMENT NOISE 4HE CHARACTERISTICS OF THIS FILTER NEED TO ADAPT TO THE QUALITY OF THE RECEIVED TARGET SIGNAL )F TRACKING IS CARRIED OUT IN GROUND REFERENCED COORDINATES  THE PROCESS AUTOMATICALLY TAKES INTO ACCOUNT OWN 
 Peters, Jr., “End-fire echo area of long, thin bodies,” IRE Trans ., vol. AP-6, pp. 133–139,  January 1958. 
 L.: Sidelobe Suppression in a Range Channel Pulse-Compression Radar, IRE Trans., vol. MIL-6, pp. 162-169, April 1962. 
 VIEWING ALTIM 
 SPEED BEAM MOVEMENT FOR HIGH 
 l 1.13c. The output of the matched filter will be a spike of width r with an ampliluc.Je N  times greater than that of the long pulse. The pulse-compression ratio is N = T/r = BT, where  B 1/r = bandwidth. 
 Thus the presence of noise will sometimes enhance'  the detection of weak signals but it may also cause the loss of a signal which would otherwise  be detected.  Weak signals such as C would riot be lost if the threshold level were lower. But too low a  tlireshold increases the likelihood that noise alone will rise above the threshold and be taken  for a real signal. 
 APERTURE RADAR SYSTEMS  DEPEND ON THE PREDETECTION SPECTRUM FOR THEIR OPERA 
 The round -trip distance is  twice that of a typical c ommunications link  and there are   losses associated with the radar cross -section and reflectivity  of target s. As can be observed from the Radar Equation, t he  range term is raised to the fourth power in the denominator,  underscoring the tremendous signal pow er losses radar  signal s experience . There are also several forms of the radar  equation that take into account differing applications and  antenna configurations. 
 WAVELENGTH ROD  WHERE THE ROD IS PARALLEL WITH THE ELECTRIC FIELD 4HIS GEOMETRY GIVES THE MAXIMUM 2#3 FOR THE ROD 4HE UPPER SCALE OF THE ABSCISSA GIVES THE ONE 
 TERING  POLARIZATION EFFECTS  AND NONLINEARITY    &OR EXAMPLE  &IGURE  SHOWS  &)'52%   2ANGE 
 8.19. A signal of frequency f,, whose phase is to be shifted an amount 4, is mixed with a  sigrial from a variable frequency oscillator fc in the first mixer. The output of the variable-  freqirency oscillator /, is also passed through a delay line with a time delay r. 
 Remote Sens.,  vol. 11, pp. 1481–1494, August 1990. 
  AND THREE 
 NEIGHBOR ASSIGNMENT IS THE MOST COMMON SOLUTION TO THIS PROBLEM 4HE  SIMPLEST FORM OF NEAREST NEIGHBOR WORKS SEQUENTIALLY ON INCOMING DATA !S EACH NEW  DETECTION IS MADE  IT IS ASSIGNED TO THE TRACK WITH WHICH IT HAS THE SMALLEST STATISTICAL DISTANCE (ENCE  IF DETECTION NO  WAS RECEIVED FIRST  IT WOULD BE ASSIGNED TO TRACK NO  (OWEVER  IT IS BETTER TO DELAY THE ASSOCIATION PROCESS SLIGHTLY SO THAT ALL DETECTIONS IN A LOCAL NEIGHBORHOOD ARE RECEIVED AND STORED AND AN ASSOCIATION TABLE  SUCH AS 4ABLE   GENERATED 4HIS HAS IMPLICATIONS ABOUT HOW SECTORS ARE SCANNED WITH A PHASED ARRAY  .EAREST 
 S band (2.0 to 4.0 GHz).  The Airport Surveillance Radar (ASR) that monitors  air traffic within the region of an airport is at S band. Its range is typically 50 to 60  nmi. 
 TARGET VELOCITY RATIO AND IS SHOWN IN &IGURE   FOR FOUR CASES #ASE  IS  WHERE THE RADAR AND TARGET SPEEDS ARE EQUAL AND THE TARGET CAN BE SEEN CLEAR OF SIDELOBE CLUTTER IN A HEAD 
 l'IWl'AOA TION OF RADAR WAVES 467  \ Sherwood, E. M ., and E. L Ginzton: Rcflectioll Coeflicients of I rregu Jar Terrain at 10 Cm, Proc. 
 Restarting the DDS for every pulse guarantees that the  same digital sequence will be input to the D/A converter for each pulse. The result is a  DDS output that only contains spectral components at multiples of the PRF . Techniques have been proposed or incorporated into DDS devices that reduce spu - rious levels by adding dithering to reduce the effects of limited word lengths. 
 POLARIZED ELEMENTS  WHICH SUPPORT POLARIZATION DIVERSITY AS WELL AS ELEVA 
 139. V . G. 
 The mutual-coupling coefficients may be easily measured for elements of all types by exciting one element and terminating each of the other elements in a matched load. The ratio of the induced voltage at element mn to the excitation voltage at element pq gives the amplitude and phase of the coupling coefficient Cmn pcf. Once these coefficients are determined, it is a simple matter to compute the mismatch for any set of phasing conditions. 
 105, pp. 8--13, 1973.  49. 
 This system can be solved according to the coefficients cij by the  measurement of three reference objects wi th known scattering matrices [ Sc1], [Sc2] and [ Sc3].   The single assumption the calibration object, however not the eventual measuring object,  should satisfy the requirement Sci,vh  = Sci,hv  .  This is a very advantageous stipulation, since  objects with defined Svh ≠ Shv, are difficult to realize, at least with monostatic RCS. 
 Long-wave radar installed inaircraft isscarcely capable ofperforming an,y function more complicated than homing, since theenormous size ofanantenna giving a beam sharp enough toproduce amap-type display precludes itsuse in aircraft. Fortunately forthe wartime development ofairborne radar, homing isatactically important function both intheattack ofshipping byaircraft and inthe interception ofhostile aircraft by defending fighters. Sets forboth purposes operating near 200 Me/see were exten- sively used during thewar. 
 116124, 1960.  9 1. This expression was suggested by Warren D. 
 TEM '03).3  4HE ON 
 41 The situation isdifferent inCase 2,forifitisrequired toreceive both first- and second-time echoes, toseparate out the latter, and topresent them inproper relation toarange scale, some method must beused which isthe equivalent ofoperation ontwo ormore frequency channels simultaneously. Various schemes tocircumvent such operation may occur tothe ingenious mind, but close examination will show that each iseither tantamount tomultichannel operation 1orinvolves some sacrifice inperformance through anabnormally wide pass band, incomplete usc ofavailable time, orthelike. Supposing that thereader accepts, with more orless reservation, the force ofithe range-PRF restriction, weproceed with the example, in which the PRF is500 pps and the range limit isaccordingly 186 miles. 
 Bell S}•stem  Tech. J., vol. 47, pp. 
 65"02)22 2 2 AAZSWATH SIN  MIN P P C    0ULSE  7IDTH 2P a $UTYMAX r 02) r C -INIMUM !LLOWABLE !MBIGUOUS 2ANGE2 MIN y H r CSC D   5 r "EL   2ANGE 3WATH IS 'EOMETRY AND )NSTRUMENTATION $EPENDENT2 SWATH a H r ;CSC D  
 The precautions mentioned thus farconstitute good design practice and canwell beincluded inany radar receiver. Toprotect against either frequency- oramplitude-modulated c-w signals, such precautions arestill necessary but not quite sufficient. Inaddition, there isneeded between the detector and video amplifier afilter that will pass individual pulses but not the c-w modulation frequencies. 
 2. A. S. 
 chosen so that for the maximum scan angle 0m the movement of a grating lobe by sin 0W does not bring the grating lobe into real space. If a scan angle of 60° from broadside is required for every plane of scan, no grating lobes may exist within a circle of radius 1 + sin 6m = 1.866. The square grid that meets this requirement has A = A=1>866 or dx = dv = 0.536Xdx dy Here, the area per element is dxdy = (0.536X)2 = 0.287X2 For an equilateral-triangular array, the requirement is satisfied by A = _A_=L866 or </=0.536X dx = 0.309X dy VIdx Since elements are located only at every other value of mn, the area per element is 2dxdy = 2(0.536X)(0.309X) = 0.332X2 For the same amount of grating-lobe suppression, the square geometry requires approximately 16 percent more elements. 
 AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .516x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 The lower threshold TL determines the probability that the correct radar track (i.e.,  the one associated with the DF signal) will be incorrectly rejected from further consid - eration. If the desired rejection rate for the correct track is PR, one can obtain this by  setting TL = PR. The threshold TH is set equal to Pfa, defined as the probability of falsely  associating a radar track with a DF signal when the DF signal does not belong with  the radar track. 
 Middleton: Optimum Sequential Detection of Signals in Noise, IRE Trans.,  vol. IT-1, pp. 5-18. 
 MERS v )%% )NT #ONF 2ADARn  #ONF 0UB   ,ONDON  /CTOBER   PP n  " , ,EWIS AND $ ( (OWARD  h3ECURITY $EVICE v 53 0ATENT        &EBRUARY      FILED !UGUST     2 , &ANTE AND * ! 4ORRES  h#ANCELLATION OF DIFFUSE JAMMER MULTIPATH BY AN AIRBORNE ADAPTIVE  RADAR v )%%% 4RANS  VOL !%3n  NO   PP n  !PRIL   3  +OGON   h!LGORITHMS  FOR  MITIGATING  TERRAIN 
 Fay: "Linear Ferrite Devices for Microwave Application." Academic  Press, New York, 1968.  29. Clarricoats, P. 
 16)video signals are derived from theupper-beam signals; this beam ischosen forMTI because itistheone predominantly used attheshorter ranges where theclutter is worse. Thus four sets ofvideo signals must betransmitted: lower-beam radar echoes, upper-beam radar echoes, upper-beam MTI video signals, and beacon responses. Time sharing isused toput two. 
 Radar is used to extend the capability of one's senses for  observing the environment, especially the sense of vision. The value of radar lies not in being a  substitute for the eye, but in doing what the eye cannot do ... Radar cannot resolve detail as well  as the eye, nor is it capable of recognizing the" color" of objects to the degree of sophistication  of which the eye is capable. 
 The parameter CIL is the ratio of the rms clutter power to the receiver-IF  limit level.  The loss of improvement factor increases with increasing complexity of the canceler.  Limiting in the three-pulse canceler will cause a 15 to 25 dB reduction in the performance  predicted by linear theory.5% four-pulse canceler (not shown) with limiting is typically only  2 dB better than the three-pulse canceler in the presence of limiting clutter and offers little  advantage. 
 Note that the RCS is ex- tremely small (not measurable in this case) at precisely end-on incidence. Theo- retical predictions in the end-on region closely match the measured pattern for this particular body. ANGULAR ORIENTATION B FIG. 
 The resistors and the bias voltage ofthe grid ofV,aresochosen that when VIisfully conducting, gjcomes toequilibrium beyond cutoff; but when VIiscut off,g~ispulled hard against the cathode. Ifleft toits “B+c2=25//Lf + c, R, 400 k --- Trigger ‘-- v,100 k ~ -lCOV(1)Trigger ~ (2) Gnd 1 ‘3) “a’el _rLnrL’+ & “)p’ate’U1-rL-r’+FIO. 13.14 .—Eccles-Jordan Sip-flop. 
 Sens. 2017 ,10, 4022–4031. [ CrossRef ] 11. 
 50. R. Bernard, M. 
 R. E. Daniel, Jr., L. 
 BASED PHASED ARRAY RADAR v  0ROC OF )%%%   2ADAR #ONF  0HILADELPHIA 53!    !PRIL n    PP n   ! &ARINA  ' 'OLINO  3 )MMEDIATA  , /RTENZI  AND , 4IMMONERI  h4ECHNIQUES TO DESIGN SUB 
 Barnum, J. R.: Ship Detection with High Resolution HF Sky wave Radar, IEEE J. Ocean. 
 9.9. The Weight ofMechanical Scanners.-The design ofamechanic- alscanner islargely dependent onitsantenna. Although only asmall percentage ofthe scanner \veight isattributable tothe antenna, alarge antenna necessitates aheavy scanner. 
 Hz on either side of the transmitter  frequency. The shape of the spectrum will depend upon the nature of the clutter illuminated  and the shape of the antenna sidelobes. For purposes of illustration it is shown in Fig. 
 WAY 
 ING TO A SIMILARLY STRONG TAILWIND OVER THE LENGTH OF THE RUNWAY #0 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.456x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 The scheme is built around two closed loops: (i) the loop encompassing the radar  model, the tracking filter, and the scheduler, and (ii) the tracking filter loop. The sce - nario is observed by the radar at time tk; the radar model provides the measurements  rk, bk, ek and SNRk. 
 With the trend toward shorter wave- length, themattress antennas aregiving way tothetypes discussed above. 9.3. Fan Beams.—One ofthefunctions forwhich airborne radars are designed isaiding airnavigation, and anextremely important type of airborne navigational radar presents amap ofthe terrain around the aircraft. 
 281, London, October19–21, 1987, pp. 582–587. 134. 
     )SORANGE CONTOURS INTERSECT AT OTHER LOCATIONS AS WELL 4HESE NONTARGET LOCATIONS ARE CALLED  GHOSTS  WHICH MUST BE  EXCISED 4HIS SUBJECT IS TREATED IN #HAPTER  OF 7ILLIS AND 'RIFFITHS.   ")34!4)# 2!$!2   ÓÎ°£ &OR EXAMPLE  WHEN THE TARGET IS SURROUNDED ON THREE SIDES BY A RECEIVE SITE  A  TRANSMIT SITE  AND ANOTHER RECEIVE SITE SUCH THAT  @     RDR   RCR    4HIS GEOMETRY  REPRESENTS THE OPTIMUM CASE OF A UNITY '$/0 FACTOR  YIELDING A CIRCULAR ERROR ELLIPSE  WITH RADIUS EQUAL TO THE RANGE ERROR OF ONE TRANSMIT 
 ING COURSE  AS SHOWN IN 4ABLE  3TATIC AND VOYAGE 
 11.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 FIGURE 11.20   GaAs MMIC processing makes use of deposition and etching techniques  to first define the active channel region of the transistor (1–4), followed by the deposition of  metals, dielectric layers, and resistive layers forming the passive components (5–8). Then,  thick metal interconnects (9) are introduced, followed by backside processing to connect RF  ground to the topside components (10–11).(1)EPIT AXIAL  LAYERS MESA  ETCH AND OXYGEN  IMPLANT  FOR ISOLA TION OHMIC MET AL PATTERNING  DEPOSITION. AND ALLOY E-BEAM (OR OPTICALL Y)  DEFINE GA TE PA TTERN,  GATE RECESS, AND GA TE  METAL DEPOSITION DEFINE CAP ACIT OR  BOTT OM PLA TE MET AL PLASMA  ETCH  TANTALUM NITRIDE PLASMA  ETCH  SILICON NITRIDE Resistor Capacitor FETDEFINE AIRBRIDGE PILLOWS,  PATTERN AND DEPOSIT  THICK MET AL, REMOVE AIR  BRIDGE PILLOWS, AND DO  FINAL  FRONT  SIDE DC TEST MOUNT  WAFER ON CARRIER  GRIND/ETCH TO 100 µm  MASK AND ETCH VIAS PLATE UP  VIAS  DEFINE GRID, DICE  AND DISMOUNT DEFINE AIRBRIDGES,  THICK MET AL  ELECTRICAL  TEST WAX SAPPHIRE100 µmDEPOSIT  Si3N4 PASSIVA TION,  FOLLOWED BY  TaN THIN FILM  RESIST ORS.(2) (3) (4) (5) (6) (7) (8) (10) (11)(9) 50 µmNITRIDE TANTALUM THICK MET AL CAP BOTT OMCAP BOTT OM GATE MET AL GaAs NITRIDE TANTALUMPHEMT  EPIT AXIAL  LAYERS GaAs SUBSTRA TE OHMIC MET AL ch11.indd   28 12/17/07   2:25:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 S. Johnson: Adaptive Detection Mode with Threshold Control as a Function of  Spatially Sampled Clutter-Level Estimates, RCA Re[]., vol. 29, pp. 
 22.4. The L-band radar transmitter was utilized with slight bandwidth changes so that resolution was 40 m on SIR-A and 20 m on SIR-B. Swath width was 50 km for both radars. 
 Chaffee, L.M.Hollingsworth, E.L.Hudspeth, R.C.Spencer, and I.G. Swope. Changing plans forthe book also reduced the acknowledged contribution ofE.C.Pollard farbelow thevery considerable quantity of material heprepared. 
 C. Roe and D. A. 
 C. Hanscn  (ed.), Academic Press, New York, 1964.  44. 
 Asimilar type ofstability isrequired ofthecoherent oscilla- tor. The apparatus designed byS.Robertsl formeasuring oscillator stability has two functions toperform. The first isthe quantitative determination ofthe rate ofchange offrequency. 
 24.50  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 • Spot jammer . It also covers the entire swath and with uniform intensity disturbing  noise as for the barrage jammer; however, its image will differ from the barrage noise  because the Fourier transform of narrower band jammer noise will result in speckle  size in the range dimension that is larger than that of thermal noise or clutter. The  processed cross-range dimension is again equal to that of clutter or thermal noise. 
 Even more striking than the Radar backscattering diagram from airplanes, are those from  ships.  At certain aspect angles huge metal surfaces are orthogonal to the incident waves and  with other angles a mirror reflection results.  The fluctuation levels of RCS are frequently over  30 dB. 
 , vol. 39, pp. 102–116, 2001. 
 Bar-Shalom and T. E. Fortmann, Tracking and Data Association , New York: Academic Press,  January 1988. 
 Keller, P. A. Lange, W. 
 Thus, the range capa­ bility of the interferometer angle measurement might be Jess than that of the 2D radar. This  reduced range capability is acceptable in many situations since the height measurement is  usually of more significance at shorter rather than longer ranges.  Lobe recognition. 
 ALLY COMPUTED BY SUMMING ALL CONTRIBUTIONS AT THE KNOWN QUANTIZATION GRATING  LOBE  ANGLES 4HE DISTRIBUTION BECOMES SMOOTHER AS THE NUMBER OF SUBARRAYS IS INCREASED OR AS THEY ARE INTERLACED £Î°ÇÊ    7 /Ê"Ê*- 
 ARRAYS  ! STRATEGY IS TO APPLY A TAPERING AT ELEMENT LEVEL IE  IN THE ANALOGUE RECEIVING SEC 
 33, pp. 139–148, 1990.  7. 
 1. W.: Frequency-scanned Arrays, chap. 13 of "Radar Handbook." M. 
 Contour plots of a scene with three point targets using: ( a) classical 2D focusing algorithm with a Taylor window; ( b) the proposed method. 5.2. Real SAR Image Simulations Simulations were also performed on a TerraSAR-X image of a part of Dingxing airport, China, which contains 500 ×300 (azimuth×range) pixels. 
 When all three sets of data are considered as one, the dashed curve shows a  saturation of a0 with wind speed above about 20 knots. However, conclusions drawn from  viewing the three sets of data as a whole may not be fully valid because of the accuracy with  -30 - -40 in u  0  b -50  -60 X ---•-----·-x-7-=- • ,t X X X  -?oo~~~5~~-10~~~15~~2~0~~2~5~~3~0~~3~5~~4~0~~4~5~~50  W,nd velocity {knots)  -30>- -40- CD u  15' -50 - -60-(a)  A A X  6 6 A_-------.-.!..--x-x---x-x-----x-- A,  A ,;/.;,. ... 
 The attenuation may be  distributed. or it may be lumped; but it is usually found within the middle third of the tube.  Loss introduced to attenuate the backward wave also reduces the power of the forward wave,  which results in a loss of efficiency. 
 Much of this is taken from Bean, Dutton, and Warner22 and  Lhermitte.25 Battan20 and Oguchi41 are also excellent sources for additional informa - tion on the absorbing properties of precipitation. Attenuation by Water Vapor.  Atmospheric water vapor may take on values up to  25 g/m3 and give variable attenuation depending on the water vapor content. 
   
 In this map the  objects which send especially strong echoes back to the  set, such as towns where there are many vertical walls  and buildings, appear as bright spots. Water areas  appear black, for they do not reflect any appreciable  radio energy back to the sender, but reflect it away. In  early H2S systems the picture was very liable to show  underexposed areas or gaps. 
 Solid-state sources at each radiating element of a large phased-array  antenna can produce the total power required for many radar applications. The radiated beam  is steered by electronic phase shifters at each element, usually on the input side of the  individual power amplifiers. The transmitter, receiver, duplexer, and phase shifters for each  element of the array antenna can be incorporated into a single integrated package, or module. 
 %FFECTS #HART  ! GRAPHICAL DISPLAY OF MIXER SPURIOUS COMPO 
 Also, the presence of/(or X) in the range equations makes it clear that the range can be frequency-dependent, but the exact nature of the frequency dependence is not always obvious because other factors in the range equation are sometimes implicitly frequency-dependent. Therefore an analysis of how the range depends on frequency can be rather complicated, and the answer depends partly on what factors are regarded as frequency-dependent and which ones are held constant as the frequency is changed. For example, most antennas have gain that is strongly frequency-dependent, but some antenna types are virtually frequency-independent over a fairly wide frequency band. 
 B. Karelitz, and L. A. 
 This causes a smoothing of the resulting signal at an addition of the single received signals. The  reflected single sign als must be independent in order to increase the maximum range by increasing  the probability of detection of the target. The disadvantage of this process is that the signals have  different spectra and therefore they are easily detected, making a target vis ible to the enemy. 
 TECTURE IS AS SKETCHED IN &IGURE   WITH AN )& CENTERED AT  -(Z AND A  -(Z ,/ AND SUPPOSE THE .#/ IS SET TO  -(Z SO THAT IT PRODUCES THE SAMPLED SINES AND COSINES SHOWN IN &IGURE A  WHERE VERTICAL LINES AND DOTS INDICATE SAMPLE TIMES AND VALUES  RESPECTIVELY "ECAUSE THE SAMPLE RATE IS FOUR TIMES THE ,/ FREQUENCY  THE COS   
 The inverting amplifier VS., which drives the opposite CRT plate, is made very linear byplate-to-grid feedback. The equal condensers inthegrid circuit ensure that thegain from point Btopoint Cisunity, tokeep themean potential ofthe deflecting plates constant (Sec. 131). 
 The phase relationship between the signals in the offset beams is not used.  The purpose of the phase-sensitive detector is to conveniently furnish the sigtt of the error  signal.  A block diagram of a monopulse radar with provision for extracting error signals In both  elevation and azimuth is shown in Fig. 
 9.Wilkins, A.F.:TheStoryofRadar,Research (London), vol.6,pp.434-440, November, 1953. 10.Rowe,A.P.:"OneStoryofRadar,"Cambridge University Press,NewYork,1948.Averyreadable description ofthehistoryofradardevelopment atTRE(Telecommunications Research Establish­ ment,England) andhowTREwentaboutitsbusiness from1935totheendofWorldWarII. 11.Watson-Watt, SirRobert:"ThreeStepstoVictory," Odhams Press,Ltd.,London, 1957;"ThePulseof Radar,"TheDialPress,Inc.,NewYork,1959. 
 No electronic beam­ steering is employed. This is an economical approach to air-surveillance radars at the  lower radar frequencies, such as VHF. It is also employed at higher frequencies when a  precise aperture illumination is required, as to obtain extremely low sidelobes. 
 A relatively simple form of electronic scan in this  application is frequency scan (Sec. 8.4) in which a change in frequency results in a change of  elevation angle.37·38 The beam can also be scanned with phase shifters.39  ~·-~--__./ One of the limitations of a long-range 3 0 radar with a single scanning beam is that the  angular coverage consists of a large number of individual beam positions so that the dwell  time in any one resolution cell is small. The ~ in -;;ch posil!Onls  <foter~ined by the time it takes for the radar energy to travel to maximum range and hack. 
 PARISON MONOPULSE ANTENNA SHOWING  SUM AND DIFFERENCE BEAMS.   2%&,%#4/2 !.4%..!3   £Ó°ÓÇ OUTPUTS TO FORM A  HIGH 
 TIONS %Q   -OST PRACTICAL RADAR 
 7) and as the integration  improvement factor (Fig. 2.8a) for substitution into the radar equation of Eq. (2.33). 
 ch09.indd   20 12/15/07   6:07:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 
 In the standard terminology of scatterometry,  the classical parameter is KP, the normalized standard deviation of the measurement.125  In the case of a fan-beam scatterometer that employs doppler filtering, the governing  expression is  KSNR SNR NTBP=+ +( / / ) 1 2 1 (18.20) where N is the number of statistically independent pulses summed into each s  0 mea - surement, T is the transmitted pulse length, B is the doppler bandwidth of the mea - surement cell, and SNR is the signal-to-noise ratio. KP usually is cited as a percent,  where values of 5% or better are the objective. Note for high SNR that KP converges  to 1 /NTB. 
 Radar 77, Publ . 155, London, 1977, pp. 53–58. 
 #/5.4%2-%!352%3   Ó{°£ &REQUENCY $IVERSITY  !NOTHER TECHNIQUE TO IMPROVE THE BLANKING PERFORMANCE  IS TO RESORT TO THE DIVERSITY OF THE RADAR CARRIER FREQUENCY IN THIS CASE  WE NEED JUST  ONE LOW 
 The ISLR along the azimuth direction is −9.8963. Figure 10. Simulation layout map. 
 It might  Iiave a frcqi~ency-respouse cliaracteristic sirnilar to that of Fig. 3.2h. The low-frequency cutoff  must be high enougll to reject tile d-c component caused by stationary targets, but yet it nlitst  be low enougli to pass the smallest doppler frequency expected. 
 When the upper two switches are open, the  lower two are closed, and vice versa. Note that in the "zero" phase state, the phase shift is  generally not zero, but is some residual amount &. Thus the two states provide a phase of 9,  and 4, + A$. 
 Moreover, it is obvious that the imaging results become clear and clear from the upper-left part of Figure 8to the lower-right part 79. Sensors 2019 ,19, 1920 of Figure 8. And the imaging result based on KA-DBS in Figure 8d performs the best. 
 In this man - ner, every element in the array sees exactly the same environment, and the calculations  for any element apply equally to all. These assumptions provide a significant simplifi - cation in the calculation of the element impedance variations. In addition, impedance  measurements made in simulators correspond to the element impedance in an infinite  array. 
 THETA LOCATION TECHNIQUE  WHERE   22   , COSP 4  SIN P4  
 pp. 71-77. January. 
 COMBINED SOLID 
 66. Schultz, F. V .. 
 Properties and design procedures based on  the Dolph-Chebyshev distribution can be found in the antenna literature. An example  of a filter design for a CPI of 9 pulses and a sidelobe requirement of 68 dB is shown in  Figure 2.54. The peak filter response can be located arbitrarily in frequency by adding  a linear-phase term to the filter coefficients. 
 A separate solid-state source  can be used at each element of the antenna, or a number of sources can be combined to feed  each row (or each column) as in the AN{fPS-59, Fig. 6.15.38 The mechanically rotating array  antenna with solid-state transmitters has some special problems of its own that must be  overcome. One such problem is the need to convey large power to the solid-state devices on  the rotating ~ntenna. 
 Very few microwave radars have  the capability-of penetrating the diffraction region to any great extent because of the severe  iosses.  The effect of the round eartli on radar coverage can be predicted by analytical means for  tile ideali7ed case of a "smooth" earth of known, uniform properties. There exist in the  literature the necessary graphs and nomographs wliich simplify the computation of radar  coverage." Coniputers may be used to perform the calculations and to automatically plot the  coverage patterns by computer-controlled plotting machines.'' Figure 12.4 illustrates, for a  particular case. 
 W.N.Sullivan. andA.S.Michaels: RadarObservations ofInsectsinFreeFlight.Sciellce. vol.154.pp.967-972. 
 The  pulse ends when the PFN has discharged sufficiently. A disadvantage of this action is  that the trailing edge of the pulse is usually not sharp since it depends on the discharge  characteristics of the PFN. It has been widely used in the past for magnetron pulsing. 
 80-107, January. 1943.  10. 
 Space.. Space vehicles have used radar for rendezvous and docking, and for landing on the  moon. Some of the largest ground-based radars are for the detection and tracking of  satellites. 
 The false alarm rate with this procedure is considerably lower than MTI with delay li ne can- cellation because of the low bandwidth of the filter.  With new devices the video signal (bip o- lar) is sampled and processed by computer.  Here, the Fourier transform replaces the filter. 
 References 1. Karimova, S. An Approach to Automated Spiral Eddy Detection in Sar Images. 
 II, April 1983. 33. Ludwig, A. 
 The theoretical rms error of the angle  measurement may be derived in a manner similar to the derivations of time (range) and  frequency errors discussed above. The analogy between the angular error and the time-delay  or frequency error comes about because the Fourier transform describes the relationship  between the radiation pattern and the aperture distribution of an antenna in a manner similar  to the relationship between the time waveform and its frequency spectrum.  For simplicity the angular error in one coordinate plane only will be considered. 
    PP n  -AY   0 $ 0OTTER  h!PPLICATION OF SPHERICAL WAVE THEORY TO #ASSEGRAINIAN 
 2. If errors are unavoidable in a reflecting antenna surface. they should be kept small in extent;  that is, for the same mechanical tolerance, the antenna with the smaller correlation interval  Figure 8.30 Plot of a, versus O/O,, where a, is the rms  phase error such that the pointing error will be In the  interval (-0, 0) with a probability p(0) for arrays with  ,412 spacing; solid curves apply for p(O) = 0.95; dashed  (3 0.02 0 04 0.06 0.08 0.10 clrrvcs apply for 140) = 0.99: 0, - anglc to the lirst 111111;  %I D = antenna length. 
 TO 
 B-SAR Phase Stability An interesting parameter for the proposed approach for blind SAR data-focusing is its phase stability: the interferometric image has been computed on real ERS1/2 tandem pair pass over the Fucino region in Italy. Figure 12shows one of the focused images of the tandem pass pair, while Figure 13shows the (5 looks, slope corrected) interferometric image obtained by B-SAR focusing algorithm with superimposed the intensity image. A close correspondence between the ﬂat zones in the valley with the smooth variationsof the phase seem to assess the good behavior and the phase stability of the proposed processing technique. 
 Their philosophy was that  if they couldn’t suppress the edge returns, the next best option would be to angle them  all into four common directions in space. Thus, all trailing edges in the B-2 are parallel  to leading edges. X-45C Unmanned Combat Vehicle. 
 G. A. Fabrizio, A. 
   ! !    " !    #  -/0(   -/0(8   -/0($ % &.   '2/5.$ %#(/  £È°xx &OR &IGURE A AND  B  THE DEPRESSION ANGLE AND TYPE ARE THE PARAMETERS  WHEREAS  FOR &IGURE  C  THE TERRAIN SLOPE IS THE PARAMETER 4HE LINES ARE BASED ON LINEAR  REGRESSION ON THE LOGARITHMIC FREQUENCY SCALE WITH THE EXCEPTION OF DESERT AND GRASS  AT VERY LOW DEPRESSION ANGLES WHERE A QUADRATIC REGRESSION WAS USED .OTE THAT URBAN  MOUNTAIN  AND FOREST TEND TO HAVE RELATIVELY HIGH VALUES COMPARED WITH AGRICULTURE AND UNCULTIVATED LAND WITH MODERATE SLOPES £È°£äÊ   Ê, ,Ê / 
 In otie iniplcrncntation, an interferometer was attached to the rotating antenna of a 2D  S-hand air-surveillaricc The 2D radar provided the range and azimuth as well as tile  tr ansniitled energy for tlic receivi~lg interferometer. Tlie interferometer consisted of four linear  Ilorizontally oriented arrays, or sticks, with one stick mounted below tlie 2D radar antenna  and tlie other three sticks mounted above.  The elevation hearnwidtlis of each of the individual antennas of the interferometer are  generally broad so that multipath due to ground reflections can cause errors. 
 TO 
 ING RESOLUTION AN ORDER OF MAGNITUDE BETTER THAN THE EARLIER  6ENERA MISSIONS   &)'52%   4HE IMPACT CRATER 'OLUBKINA ON THE SURFACE OF 6ENUS IMAGED  BY -AGELLAN 3 BAND  (( 
 For a RAR with an unweighted  aperture function, the transmitted intensity at the peak of the first angular sidelobe  is reduced by –13 dB, and the received intensity from a target in that direction is  thus reduced by –26 dB. For a SAR, typically the entire region of the image is in the  main beam during the data collection, and there are no effects from the sidelobes of  the physical antenna. The sidelobes result solely from the processing, and (with no  weighting) the first sidelobe is reduced by –13 dB relative to the main beam. 
 FREQUENCY TRACKING  RADAR v -ICROWAVE *  VOL   PP n  3EPTEMBER   6 7 (AMMOND AND + ( 7EDGE  h4HE APPLICATION OF PHASED 
 It is immediately noted that cloud or fog attenuation is an order of magnitude greater at 3.2 cm than at 10 cm. Nearly another order-of-magnitude increase occurs between 3.2 and 1.25 cm. Range and Velocity Ambiguities. 
 AN/TPS-59 Tactical Solid State Radar, brochure, General Electric Company. 24. AN/TPS-59: First Total Solid State Radar, ADCOM Commun. 
 DIMENSIONAL  METAL WEDGE AS APPLIED TO A THREE 
 BASED SYSTEM USED FOR DOWNLINK BISTATIC RADAR 4HE LOW 
 Knott, The Boeing Company (CHAPTER 11) William H. Long, Westinghouse Electric Corporation (CHAPTER 17) David H. Mooney, Westinghouse Electric Corporation (CHAPTER 17) Richard K. 
 The deflection of the beam or the  appearance of an intensity-modulated spot on a radar display caused by the presence of a  target is commonly referred to as a blip.  The focusing and deflection of the electron beam may be accomplished electrostatically,  electromagnetically, or by a combination of the two. Electrostatic deflection CRTs use an  electric field applied to pairs of deflecting electrodes, or plates, to deflect the electron beam. 
 18.54  18.12 Error Reduction Te chniques  ...................................  18.54  Multipath-Error Reduction  ..................................  18.54  Target Angle and Range Scintillation (Glint)  Reduction  ........................................................ 
 121 and described inSec. 12.2. Either an electrostatic oramagnetic cathode-ray tube can beused, the former being much cheaper but far less satisfactory. 
 7.31  Array Simulators  ................................................  7.32  Compensation for Scanned Impedance  Variation  ..........................................................  7.35 . 
 CENTERED,    2 - 22  24s 0LANETARY EXPLORATION s !IR THREAT MONITORING s -ISSILE LAUNCH ALERT4!",%  "ISTATIC 2ADAR !PPLICATIONS. ÓÎ°£ä  2!$!2 (!.$"//+  &URTHERMORE  THIS APPROACH IS LESS COSTLY AND WHEN EXPLOITING NONCOOPERATIVE TRANS 
 4, pp. 1271–1292, 1998. 184. 
 The approach resonant wave peak is about 20 dB larger than the recede peak, indicating an almost direct sea into the radar. The processing used in developing these displays was 200-s CIT and 30-min averaging. This order of time for processing is appropriate for surface-target speeds and ground-wave radar; it also shows in doppler detail the form of the sea echo. 
 )  &&!$ '$       !%&  && !    &$& !  '$       ($&    &$   !"" $    &$      && ! %'& ! &&  &&            ($   !!!! %% ! %    .   05,3% $/00,%2 2!$!2   {°Ó£ &)'52%  0ROBABILITY OF DETECTION VERSUS SIGNAL 
 2005 ,43, 874–887. [CrossRef ] 6. Bovolo, F.; Bruzzone, L. 
 TO 
 1 Varian brothers, Palo Alto, ca. 1935   2 Karl Ferdi nand Braun, 1850  – 1918, Braun Cathode Ray Tube 1896, Nobelpize 1909  . Radar System Engineering  Chapter 1 – History of Radar Technology  4        Figure 1.3  Radar apparatus Freya, Telefunken 1937   Beginning at the end of the 50’ s Radar technology also saw increasing innovation in the comp o- nent and signal processing sectors. 
 23. J. R. 
 VOLTAGE CONTINUUM ) 
 But for the moment we  can imagine the aerial itself to be, say, a vertical rod cut  to an exact fraction of the wavelength used, and there-  fore resonating most readily at the desired frequency; a  rod equal in length to half of the wavelength is com-  monly used. This rod will propagate waves in all direc-  tions, but if we stand a series of somewhat similar rods  . 56 HOW RADAR WORKS  at proper intervals m one direction we shall make them  resonate too, and we shall thus get a strong transmission  in this particular direction. 
 D.: Radar Imaging from a Distributed Array: The Radio Camera Algo- rithm and Experiments, IEEE Trans., vol. AP-29, pp. 740-748, September 1981. 
 GROUND PENETRATING RADAR  21.416x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 13. Cook and Bernfeld, Radar Signals, An Introduction to Theory and Application , Norwood, MA:  Artech House, p. 9. 
 For targets with sufficient radial velocity, high PRF is typically more efficient than  medium PRF. The transmit pulse width is usually limited by the transmitter’s ability to  preserve the pulse amplitude and phase characteristics over the duration of the transmit  pulse. For a fixed transmit pulse width and peak power, a waveform with a higher PRF  will have a higher transmit duty cycle resulting in a higher average transmit power. 
 [ CrossRef ] 9. Jiang, Y. Optical/SAR image registration based on cross-correlation with multi-scale and multi-direction Gabor characteristic matrixes. 
 23 bternally coherent MTI.138 Falsealarm.17 Falsealarmnumber. 30 Falsealarmprobability. 24 Falsealarmtime.24-26,32 Farfield.antenna. 
 (Source: http://www.darpa   .mil/DARPATech2000/Presentations/spo_pdf/4MoyerCCTB&W.pdf ) Photograph FOPEN SAR ImageConventional SAR ImageExample of Foliage-Obscured Vehicles • Depression Angle:  45°, Resolution:  1 m × 1 m  • Vehicles Mask ed By Trees, Along Logging Road in Maine ch17.indd   34 12/17/07   6:50:13 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 
 Note the fluctuations due to scalloping loss as the  source moved through FFT range bins. ch20.indd   74 12/20/07   1:17:15 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 J., vol. 18,  pp. 222 -234. 
 The extraction of information generally requires a matched filter, or its equivalent, for optimum processing. The more information that is known about the target a priori, the more efficient will be the detection. For example, if the target location were known, the antenna could be pointed in the proper direction and energy or time need not be wasted searching empty space. 
 H. Stiles, F. T. 
 PLACEMENTS FOR EACH PULSE )N ORDER TO MAINTAIN THE EFFECTIVE 02&  THE DISPLACEMENT MUST COMPENSATE FOR THE TWO 
 5.4. Two fan beams arc dis placed ("squinted .. ) in elevation angle and  the sum and dilTercnce patterns are obtained. 
 A. Farina, G. Golino, and L. 
 The matched filter radar receiver provides an optimum linear processing of radar in  the presence of noise. The radar signal is processed by a filter that cross-correlates the  received waveform with a suitably time-delayed version of the transmitted waveform.  The output results in an output in which the amplitude of the latter and its position in  delay time is related to the target radar characteristic. 
 SCALE SUBSIDENCE WILL LEAD TO SUPERREFRACTIVE LAYERS ALOFT 3UPERREFRACTIVE LAYERS WILL LEAD TO AN INCREASE OF RADAR DETECTION RANGES AND EXTENSIONS OF THE RADIO HORIZON 4HE EFFECTS OF A SUPERREFRACTIVE LAYER UPON A SURFACE 
 4.4 RANGE AND DOPPLER AMBIGUITY RESOLUTON Medium and high-medium PRF waveforms usually use multiple discrete PRF ranging  to resolve range ambiguities, while linear FM ranging is commonly employed when  high-PRF waveforms are used. Multiple Discrete PRF Ranging.  The techniques for calculating true range  from several ambiguous measurements generally involve sequential measurement of  the ambiguous range in each PRF, followed by an unfolding  and correlation process. 
 3, pp. 97-102, February, 1974.  6. 
 Filter Characteristics.  Filter responses are characterized fully by either their  frequency response H(w) or their impulse response h(t); however, they are usually  specified by a variety of parameters as described below. Digital filters may be speci - fied using the same measures, or because they can be specified exactly, they are fre - quently specified by their transfer function H(z) or impulse response h(n). 
 The equipment isshown inFig. 77. The camera uses 16-mm film, ofWhich 350 ftarerequired forcon- tinuous 24-hr operation attwo scans perminute. 
 Lucas, D. L., J. L. 
 LAW DETECTION &OR SQUARE 
 The permissible range ofincident angle isthe other electrical factor limiting the shape ofthe radome. The range ofsatisfactory incident radiation transmission varies with different materials and radome wall constructions. The properties ofthematerials affecting thetransmission arethe dielectric constant and the loss tangent; thelatter isanindex of theabsorption and theformer isafactor determining thereflection. 
 Radar Conf ., London, 1982, pp. 71–75. 33. 
 Resonant cavities were later replaced by wider-band circuits, which were related to  the type of circuits used in TWTs. Such klystrons are known as the Clustered Cavity  Klystron, Extended Interaction Klystron, and the Twystron. When considering a trans - mitter for high-performance radar, these variants of the klystron are likely to be highly  favored for many applications. 
 PERATURE !LTHOUGH THE TRANSISTOR MAY OPERATE RELIABLY AT A DESIRED OUTPUT POWER LEVEL FOR THE SHORTER PULSE WIDTH  IT WOULD SUFFER FROM A DECREASE IN LONG 
 P..andA.Spizzichino: ..TheScattering ofElectrom,ignetic WavesfromRoughSur­ faces,"TheMacmillan Company. NewYork.1963. 59.Kalmus, H.P.:Doppler WaveRecognition withHighClutterRejection. 
 Anautomatic cir- cuit searched inrange inthe absence ofatarget, and locked onand tracked atarget when anecho was encountered within the 2000-yd coverage ofthe set. This range circuit was used tobrighten the spot only when atarget was inrange, inorder todistinguish between correct pointing and the absence ofatarget. Italso caused the target spot to grow horizontal “wings” whose spread increased asthe range grew shorter, inorder toprovide anindication ofrange tothe gunner (see Fig. 
 19). While these seekers are clearly a bistatic radar configuration, missile engineers have developed a different lexicon to describe their technology and operation, e.g., semiactive versus bistatic, illuminator versus transmitter, rear reference signal versus direct-path signal, etc. The missile and radar communities continue to go their separate ways. 
 TO 
   IN AXIS I  FI  FV     VIBRATION POWER SPECTRAL DENSITY G(Z  IN AXIS  I AT THE VIBRATION   FREQUENCY FV 4HE COMPOSITE 34!,/ VIBRATION SENSITIVITY  '  IS DEFINED BY THE ROOT SUM SQUARE  OF THE SENSITIVITY IN EACH OF THE THREE PRIME AXES  AS SHOWN IN %Q    \\' '''    XYZ    2ANGE $EPENDENCE  -OST MODERN RADARS USE THE 34!,/ IN BOTH THE RECEIVER  FOR DOWNCONVERSION AND THE EXCITER FOR UPCONVERSION 4HIS DOUBLE USE OF THE 34!,/  INTRODUCES A DEPENDENCE ON RANGE OF THE CLUTTER AND EXAGGERATES THE EFFECT OF CERTAIN UNINTENTIONAL PHASE 
 COMPRESSED WAVEFORMS WITH HIGH PRECISION AND AT LOW COST 4HESE WAVEFORMS ENABLE COH ERENT PROCESSING OF  THE RECEIVED SIGNAL  GIVING ADDITIONAL DOPPLER INFORMATION THAT CAN BE USED TO HELP SEPARATE TARGETS FROM CLUTTER 4HE USE OF FREQUENCY DIVERSITY TECHNIQUES TO GIVE ADDED TARGET DETECTION POSSIBILITIES BECOMES POTENTIALLY AFFORDABLE  BECAUSE OF THE FLEXIBILITY OF THE SIGNAL GENERATION TECHNOLOGY #OST HAS PRECLUDED THE USE OF DUAL 
 Results were validated by using independent levelling measurements, demonstrating that the proposed modelling method allows improving the estimation of the nonlinear component of the deformation. 2.5. T arget Discrimination and Change Detection Thanks to the information content available under all-weather conditions and also during night-time, SAR is widely used for target detection, classiﬁcation and change detection. 
 Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 5.40  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 An example thresholding scheme based on these concepts is shown in Figure 5.37.  The range-doppler space is broken up into a grid of range bins and doppler filters, as  shown in the figure. 
 +1/"  ! FORM OF THE RADAR EQUATION  %Q   CAN BE USED TO POINT TO ASPECTS OF (& RADAR THAT ARE SIGNIFICANTLY DIFFERENT FROM RADARS THAT USE HIGHER FREQUENCIES 4HESE DIFFER 
 Among the 1792 modules per face, groups of 32 T/R modules are operated as a  subarray. In transmit, a high-power array predriver is used to drive 56 subarray driver  amplifiers. Each of these power amplifiers provides enough RF drive for all 32 mod - ules in one subarray. 
 Maintenance of  tlic iriterrial pressure in liigli winds can sometimes be difficult. Another problem is that costly  ~naintena~~ce is reqirir-cd at f~cqucrlt i~itcrvals.  The limitations of air-supported radomes are overcome by the use of rigid self-supporting  radornes. 
 18–27, March 1963. 20. J. 
 Kayton and W. R.  Fried (eds.). 
 POLAR 
 pp. 76-80.  1)ccenl ber. 
 There are other effects that should probably be part of any complete theory of sea  clutter. Such factors include: the shadowing of the waves when the surface is viewed at low  grazing angle; the specular reflection from plane facets when viewed at near normal incidence;  the effect of breaking waves, whitecaps, and foam, especially when the winds are greater than  about 15 to 20 knots; and the presence of refraction effects, such as that due to the evaporation  duct over the surface of the sea, which enhance the propagation of radar waves near zero  grazing angle so that sea clutter is increased at the longer ranges compared to normal  propagation conditions.  Backscatter from sea ice. 
 The PPI range is 40 nmi. FIGURE 2.2  Simplified block diagram of a coherent MTI system TRANSMITTERRF OSCILLA TOR DUPLEXER PHASE DETECT ORANTENNA + MTI FIL TERT Σ −Bipolar Video ch02.indd   3 12/20/07   1:42:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Moore, “Radar scattering cross-section per unit area and radar astronomy,” IEEE Spectrum ,  p. 156, April 1966.  4. 
 KM SWATH WIDTH 3POT3!2 MODE IS SUPPORTED BY CONTROLLED YAW MANEUVERS OF THE SPACECRAFT !LL OF THE SPACECRAFT IN THE SERIES FIVE RADARS AND SIX OPTICAL SYSTEMS  USE SUN 
 butthegreatertheprobability offalsealarm. Abankofnarrowband filtersmaybeusedafterthedetector inthevideoofthesimpleCW radarofFig.3.2insteadofintheIF.Theimprovement insignal-to-noise ratiowithavideo filterbankisnotasgoodascanbeobtained withanIFfilterbank,buttheabilitytomeasure themagnitude ofdoppler frequency isstillpreserved. Because offoldover, afrequency which liestoonesideoftheIFcarrierappears, afterdetection, atthesamevideofrequency asone whichliesanequalamountontheothersideoftheIF.Therefore thesignofthedoppler shiftis lostwithavideofilterbank,anditcannotbedirectly determined whether thedoppler frequency corresponds toanapproaching ortoareceding target.(Thesignofthedoppler may bedetermined inthevideobyothermeans,asdescribed later.)Oneadvantage ofthefoldover inthevideoisthatonlyhalfthenumberoffiltersarerequired thanintheIFfilterbank.The equivalent ofabankofcontiguous bandpass filtersmayalsobeobtained byconverting the analogIForvideosignaltoasetofsampled, quantized signalswhichareprocessed with digitalcircuitry bymeansofthefastFourier transform algorithm.16 Ahankofoverlapping doppler filters.whether intheIForvideo,increases thecomplexity fthereceiver. 
 Earl, and M. Tyler, “High frequency radar cross section  measurements of surrogate go-fast boats in Darwin, Australia,” SPAWAR System Center Tech.  Rept. 
 Suitable isolation from excessive voltage-standing-wave ratio (VSWR) must be provided to protect the microwave transistors, and their harmonic power output must be properly filtered to meet MIL-STD-469 and other specifications on RF spectrum quality. Because most microwave transistors operate Class-C, no pulse modulators are required, but Class-C operation makes it more difficult to provide controlled shaping of the RF rise and fall time for spectrum control. Also, just as in tube-type transmitters, energy management is still crucial. 
 These clear-air radars receive energy backscattered from refractive index inho - mogeneities caused by naturally occurring atmospheric turbulence.184 The antenna  systems usually take the form of phased arrays that form beams several degrees  wide that are switched to 3, 4, or 5 nearly vertical beams for 1–2 minutes each and  measure vertical profiles of wind every 5–30 minutes. The antennas are frequently  of the coaxial collinear (co-co) style for those radars and Yagi array elements for  those at the higher frequencies. The higher frequency UHF profilers typically use  either Yagi or microstrip patch array antennas. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.4  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 Consider the set of tasks and DIRs shown in Figure 20.3. 
 Itfollows that Qo,forcavities ofsimilar shape, varies asl/@o. Onthe other hand, the Qvalues that can be attained atmicrowave frequencies, typified bythe example just given, aremuch higher than can bcrealized with coil and condenser combina-. SEC. 
 I EE£  Trans., vol. AES-5, PP~ 195-2041 March, 1969. ,;. 
 This was done by Wetzel,12 who showed in detail how diffraction, rather than shadowing, controls propagation into and out of the troughs of the waves under many of the usual frequencies and wind speeds encountered in practical radar operations at low grazing angles. For example, shadowing will take place at Ka band for any winds above 15 kn, yet will hardly ever occur at L-band frequencies. Contaminants. 
 h!ic.r.orr~rr[~c~ Resrarcl~ Itrsrit~rtr S~ltnposiu Series, Jerome Fox (ed.), Polytechnic Press, Brooklyn. New  York, 1971, pp. 9-25. 
 BASED 3!2S 3WATH WIDTHS ACHIEVED ARE AS MUCH AS FIVE TIMES THE NOMINAL STRIP 
 Lowered gain at low alti-  tudes also helps to reduce interference from unwanted retlections. The response at the upper  end of the frequency characteristic is rapidly reduced for frequencies beyond that correspond-  ing to maximum range. If there is a minimum target range, the response is also cut off at the  low-frequency end, to further reduce the extraneous noise entering the receiver. 
 (2.2). A further convenient modification is to redefine Pt as the transmitter power at the terminals of the transmitter, rather than [as in Eq. (2.1)] the usually somewhat smaller power that is actually delivered to the antenna terminals because of loss in the transmission line. 
 The filter is usually set by the acquisition problem or the time on target rather than by the intrinsic character of the return signal. Rapid antenna scan, however, can cause an appreciable broadening of the spectrum produced by the clutter. Were it not for the particular shape of the typical antenna beam, the transients produced by clutter while scanning would be far more serious. 
 30 INTRODUCTION TO RADAR SYSTEMS  The comparison or predetection and postdetection integration may be briefly summarized  by stating that although postdetection integration is not as efficient as pn.:detection integra­ tion, it is easier to implement in most applications. Postdetection integration is therefore  preforred, even though the integrated signal-to-noise ratio may not be as great. As mentioned  in Sec. 
 .. .. 680 INTRODUCTION ............................680 17.1 The Usesof Radar Relay. 
 [ CrossRef ] 13. Makedonas, A.; Theoharatos, C.; Tsagaris, V .; Anastasopoulos, V .; Costicoglou, S. Vessel classiﬁcation in cosmo-skymed SAR data using hierarchical feature selection. 
 7.1.2  Quadrature Modulation   Through the application of two mixers, which is practiced in quadrature modulation (phase  difference of 90° for the os cillator), the sign (+/ -) of the Doppler Frequency can be evaluated.   A quadrature demodulator (I/Q -Demodulator) determines the allocation of the receiving si g- nal, which is indicated with reference in -phase (I) or quadrature (Q) (meaning perpendicular),  as shown in Figure 7.4.  . 
 52-53, July, 1974.  52. Goldie, H.: Radioactive (Tritium) lgnitors for Plasma Limiters, IEEE Trans., vol. 
                           
 79, pp. 867–880, 1991. 104. 
  
 6, December 2002. 39. A. 
 From the 1960s onwards, the use of a slotted waveguide linear array, mounted in  a linear flared horn has been the most common antenna solution for shipborne radars.  Because at least horizontal polarization has to be provided on 9 GHz SOLAS radars,  slotted array solutions generally have their slots cut into the narrow wall of the horizon - tally mounted waveguide. A vertical slot (perpendicular to the waveguide edge) couples  no power, but as the slot is increasingly angled, more power is coupled out. 
 1029–1078, 1983. 42. R. 
   2!$!2 #2/33 3%#4)/.   £{° 4HE PLATE IS PRESENTED BROADSIDE TO THE INCIDENT WAVE AT THE CENTER OF THE CHART  n   AND IS SEEN EDGE 
 there will be some angle at which these two counteracting effects result in  niaxitnilnl efficiency. This is illustrated in Fig. 7.8 for the circular-waveguide feed whose pat-  ter~~ is showtl in Fig. 
 Pell, C., et al.: An Experimental Bistatic Radar Trials System, IEE Colloq. Ground Air- borne Multistatic Radar, pp. 6/1-6/12, London, 1981. 
 The presence of swell waves  along with the wind-driven sea can also affect the radar backscatter. Still another important  factor when attempting to understand the effect of the wind on sea clutter is the difficulty  in accuratelf estimating wind speed at sea.6 .  Effect of pulse width. 
 These are passed through aphase splitter and apush-pull amplifier to the vertical deflecting coils. Since the sweep isalways inthe same FromDifferential mechamcalgear repeater—- Potenti-—Sawtooth ometer generator J_ Sector control 1 30CRT — lk’DelayFlip.flopcircuit Flip.flopSawtooth—generator— Amplifier FIG.1353.-V-beam height indicator, direction, d-crestorers provide adequate clamping onthe output stages. The horizontal sweep, ofconstant amplitude, isgenerated intheordinary way and amplified aswas the vertical one. 
 F. F. Marzano, E. 
 EA = EAM + KEA(2<,_a}e-*++2D™<» E8 = EBM + KEB(26+a]e-M+2D sin 9> (20.21) where K = amplitude of reflection coefficient 4> = phase of reflection coefficient EAM = EB(CL) = relative received field strength of beams A and B from sig- nal arriving along direct path at angle a from peaks of beams A and B EAW-CL) = relative received field strength of beam A from reflected path at 20 - a from peak of beam A EBW+GL) = relative received field strength of beam B from reflected path at 20 + a from peak of beam B The magnitude of the off-boresight elevation-angle error due to ground reflec- tions is a function of the ratio of the magnitudes of EA and EB, or \EA\ lEA(a) + KEA(2Q_a)e-M+2D™V\ Elevation error = / = / (20.22)\ER\ IF 4- KV ^-y^+ZDsine), B ^B(OL) + &£<B(2Q+a)e ' When KEA(2Q_a) and KEB(2Q+OL) are small compared with EA(a)9 the maximum value of f(\EA\I\EBI) is equal to EA(a.) + KEA(2Q-a) F Kt (2°'23)^B(OL) A/i£(2e + a) To illustrate these effects, a specific example is cited where the amplitude comparison beams A and B are assumed to have the following characteristics: Antenna aperature (a) = 25.5\ sin [ir(a/X) sin 6] sin (25.5Tr sin 0)Receiving beam pattern function =ir(a/X) sin 0 25.5-rr sin 0 Beamwidth (at-3 dB points) = 2.0° Squint angle (a) = 1.125° Antenna height above ground = 5OX The ground-reflection coefficient Ke^ is assumed to be 1.Oe^, which corre- sponds to horizontal polarization over an infinite conducting plane. With these values, Fig. 20.10 shows a plot of the resultant relative field strengths in beams A and B as a function of the elevation boresight pointing angle 0. 
 COATED DIELECTRICS ALUMINUM  SILVER  OR ZINC OVER FIBERGLASS OR NYLON . 
 D.: Synthesis of Comb ~ilters, Proc. Narl. ConJ on Aeronaut. 
 This will be better appreciated as we proceed  through the chapter and note the various factors that must be taken into account. J  A complete and detailed discussion of all those factors that influence the prediction of  radar range is beyond the scope of a single chapter. For this reason many subjects will appear  to be treated only lightly. 
 Low-power grid-control tubeshavebeen used inphasedarrayradarsatUHFandhave provcn tobeaneconomical andreliable sourceofpower.IntheAN/FPS-85 satellite­ surveillance radarbuiltbyBendixCorporation fortheU.S.AirForce,thetransmit arraycon­ tains5184identical modules usingtheEimac4CPX250K ceramic tetrode.23Eachmodulehas apeakpoweror10kWandis7by9by31incheswithaweightornearly 50lb.Thearrayoperates witha10MHzhandwidth centered at442MHz.. 21 4 INTRODUCTION TO RADAR SYSTEMS  6.8 MODULATORS  The function of the modulator is to turn the transmitting tube on and off to generate the  desired waveform. When the transmitted waveform is a pulse, the modulator is sometimes  called a pulser. 
 642 16.7 Fluctuations Due toScanning 644 16.8 Receiver Characteristics : 646 16.9 Target Visibility .........,...,..,.....649 16.10 Choice ofSystem Constamts. 653 MOVING-TABGET INDICATION ONAMOVING SYSTEM . 655 16.11 Compensation forVelocity ofSystem .. 
 Given a time T0 (sec) allocated to the measure - ment and a signal bandwidth sf (Hz), there will be approximately sfT0 independent  samples of the square of the signal envelope. It follows, therefore, that for the high  SNR case an estimate of the mean power for this process ˆPr will have a variance or  mean square error given by  var(ˆ)PP Trr f≈2 0σ (19.40) Substituting for sf from the expression sf = 2sv/l, where sv is the width of the  doppler spectrum, Eq. 19.40 becomes  var(ˆ)PP Trr v≈λ σ2 0 2 (19.41) This expression is valid for high signal-to-noise cases. 
 Skolnik (ed.), New York: McGraw-Hill Book Company, 1970, pp. 24-1–24-40. ch19.indd   41 12/20/07   5:39:20 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 LIMITED CONDITION  4HE RADIUS  R0 OF THE AREA DELIMITED ON A QUASI 
 OPTICAL TRANSMISSION LINE AND PRODUCES A  n BEAM WITH EXTREMELY LOW SIDELOBES 4HESE RADAR DESIGN  PARAMETERS ALLOW AN EXCEPTIONAL SENSITIVITY OF n D": AT THE %ARTH SURFACE #LOUD3AT ORBITS IN FORMATION WITH FOUR OTHER SATELLITES AS PART OF THE SO 
 A. Munk: A Streamlined Metallic Radome, IEEE Trans., vol. AP-22, pp. 
 BEAM ANTENNA . Ó°£ää  2!$!2 (!.$"//+  LOGIC PERMITS RETAINING MANY OF THE TARGETS WITH SMALLER RADIAL VELOCITIES IF THEIR 2#3  IS LARGE ENOUGH 36# STILL REJECTS BIRD CLUTTER  BUT RETAINS  FOR EXAMPLE  THE FAST INCOM 
 Accuracy is a measure for how large the tolerances  for the determination of the info rmation parameters, such as distance, speed, etc. are.  The accu- racy describes thus, with which relative or absolute errors the measured variable can be dete r- mined. 
 The illuminator, for example, might be at  the launch platform. CW illumination has been used in many successful systems. An example  is the Hawk tracking illuminator shown in Fig. 
 DOMAIN WAVEFORMS  WHERE THE FIDELITY OF THE OUTPUT MAY BE A REQUIREMENT 4HE 7IENER FILTER SEPARATES SIGNALS BASED ON THEIR FREQUENCY SPECTRA 4HE GAIN OF  THE 7IENER FILTER AT EACH FREQUENCY IS DETERMINED BY THE RELATI VE AMOUNT OF SIGNAL AND  NOISE AT THAT FREQUENCY 4HE 7IENER AND MATCHED FILTER MUST BE CARRIED OUT BY  CONVOLU 
 These losses, denoted LRY, might be due to the  receiver transmission line, duplexer, rotary joint, preselector filter, monitoring devices, or loss  in the randome. The noise figure due to these RF losses may be derived from the definition of  Eq. (9. 
 This  can be seen from Figure 13.19 as the difference between P = 0.5 and P = 0.999  or P = 0.9999. If this allowance is not granted, the antenna will be overdesigned.  It is worthwhile to do some probability calculations before specifying the exact  sidelobe requirements. 
 ('liariipine. (i. A.: ('otnputer Control of Array Radar, Sprrry Enginerrinq Retie#'. 
 MODEL 2#3 BY THE SQUARE OF THE RATIO OF THE TWO FREQUENCIES )N THIS EXAMPLE  THAT FACTOR IS     OR  D" /UTDOOR 4EST 2ANGES  /UTDOOR TEST RANGES ARE REQUIRED WHEN TEST TARGETS ARE TOO  LARGE TO BE MEASURED INDOORS 4HE FAR 
 Thefilteroutputismixedwiththe(third)harmonic offm.Thedoppler frequency isextracted bythelow-pass filter. Sincethetotalenergycontained inthebeat-frequency signalisdistributed amongallthe harmonics, extracting butonecomponent wastessignalenergycontained intheotherhar­ monicsandresultsinalossofsignalascompared withanidealCWradar.However, the signal-to-noise ratioisgenerally superior intheFMradardesigned tooperate withthe/lth t--~------1 Transmitter ~-'--"H fmFrequencymodulotion x3 frequency multiplier 3dharmonic filterDoppler frequency Figure3.17Sinusoidally modulated FM-CW radarextracting thethirdharmonic (J3Besselcomponent).. harmoriic as compared with a practical CW radar because the transmitter leakage noise is  suppressed by the 11th-order Ressel function. 
 CM WAVELENGTHS HAVE BEEN WIDELY CHOSEN FOR MOST PRECIPITATION MEASUREMENTS OF INTEREST IN WHICH DESIGN PARAMETERS SUCH AS RADAR BEAMWIDTH  SIZE OF ANTENNA  AND ATTENUATION EFFECTS MAY BE MADE ACCEPTABLE 'ROUND #LUTTER %FFECTS  -ANY METEOROLOGICAL RADAR APPLICATIONS CALL FOR THE  DETECTION OF PRECIPITATION ECHOES IN THE PRESENCE OF GROUND CLUTTER 3PECIFICALLY  PRE 
 1529–1534, 1996. 14. V . 
     $EVIATIONS FROM THE IDEAL MATCHED FILTER RESPONSE  (-V  PRODUCE A REDUCTION IN  3.2 TERMED  MISMATCH LOSS 4HIS LOSS CAN OCCUR FOR A NUMBER OF REASONS SUCH AS TARGET  DOPPLER OR BECAUSE A FILTER RESPONSE IS CHOSEN THAT IS DIFFERENT FROM THE MATCHED FILTER RESPONSE IN ORDER TO MINIMIZE ANOTHER PARAMETER SUCH AS RANGE SIDELOBES 2ECEIVER FILTERING IS OFTEN MODIFIED FOR DIFFERENT WAVEFORMS USED 7HEN RADAR SYS 
 TION BY SPREAD 
 TO 
    
 The ability of an operator to extract information efficiently from a CRT display will  depend on such factors as the brightness of the display, density and character of the back­ ground noise, pulse repetition rate, scan rate of the antenna beam, signal clipping, decay time  of the phosphor, length of time of blip exposure, blip size, viewing distance, ambient illumina·  tion, dark adaptation, display size, and operator fatigue. Empirical data derived from exper­ imental testing of many of these factors are available.28•29  There has been much interest in applying solid-state technology as a radar display to  replace the vacuum-tube CRT. Although the light-emitting diode has been too costly and  complex to be a general replacement for the CRT, it might be applied when required to display  limited information without the display occupying excessive space, such as in the Distance  from Touchdown Indicator (DFTI) used in aircraft control towers to monitor landing  aircraft.27 Liquid crystal displays which can operate in high ambient lighting conditions have  also been of interest for some special radar requirements, but they also are limited compared  to the capability of a CRT. 
 Theminitrack systemisanexample ofaninterferometer in whichangular ambiguities areresolved inamannerstmilartothatdescribed.64 Themultiple-frequency CWradartechnique hasbeenappliedtotheaccurate measure­ mentofdistance insurveying andinmissileguidance. TheTellurometer isthenamegiventoa portable electronic surveying instrument whichisbasedonthisprinciple.57-59Itconsistsofa masterunitatoneendofthelineandaremoteunitattheotherend.Themasterunittransmits acarrierfrequency of3,000MHz,withfoursingle-sideband modulated frequencies separated fromthecarrierby10.000,9.990,9.900,and9.000MHz.ThelO-MHz difference frequency provides thebasicaccuracy measurement, whilethedifference frequencies of1MHz,100kHz, and10kHzpermittheresolution ofambiguities. Theremoteunitattheotherendofthelinereceivesthesignalsfromthemasterunitand amplifies andretransmits them.Thephasesofthereturned signalsatthemasterunitare compared withthephasesoftheoutgoing signals.Sincethemasterandtheremoteunitsare stationary, thereisnodoppler frequency shift.Thefunction ofthedoppler frequency is provided bymodulating theretransmitted signalsattheremoteunitinsuchamannerthata l-kHzbeatfrequency isobtained fromtheheterodyning processatthereceiverofthemaster UIIit.ThephaseoftheI-kHzsignalscontaiils thesameinformation asthephaseofthemultipie frcque1cics. 
 Theassumption ofhazardous nontherma·1 effectsatlowdensities ofradiation isafearthathas notbeensubstantiated.69Thedemonstration ofabiological effectduetomicrowaves doesnot ofnecessity demonstrate aperil.Confusion alsocanresultattimesbetwecn microwaves and othermoreharmful radiations. Microwave radiation isnonionizing andisvastlydifferent fromionizing radiations suchasXrays. Asasafetyprecaution, areasofhighpowerdensity shouldbcfencedoff,locked,or otherwise madeinaccessible whentransmitting. 
 Atatemperature oflOOC,thevalueof 1m(-K)forwaterisO,006XX whenthewavelength istoem(5band)and0.0247for3.2-cm wavelength (Xband).71 Equation (13.2R)isagoodapproximation forrainattenuation at S-bandorlongerwavelengths. Sincerainattenuation isusuallysmallandunimportant atthe longerwavelengths wherethisexpression isvalid,thesimplicity offered bytheRayleigh scattering approximation isoflimiteduseforpredicting theattenuation through rain. Thecomputation ofrainatt"nuation musttherefore bebasedontheexactformulation for spheres asdeveloped byMie.1hTheresultsofsuchcomputations arcshowninFig.D.Dasa function ofthewavelength andtherainfallrate. 
   PP n    4 
 LESS OF COMPLEXITY  HAS FIVE FUNDAMENTAL FUNCTIONS   TO PROVIDE GAIN AND POWER OUTPUT IN THE TRANSMIT MODE    TO PROVIDE GAIN AND LOW 
 738–751, May 1999.  8. R. 
 198 INTRODUCTION TO RADAR SYSTEMS  The standing-wave pattern along a transmission line repeats itself every half wavelength;  therefore, 360° in the diagram is taken as a. half wavelength. The reference axis in the Rieke  diagram usually corresponds to the output terminals of the magnetron or the output flange of  the waveguide. 
 The high-power capability of the klystron, like anything else, is not unlimited. One of the  major factors which has restricted the power available from klystrons has been the problem of  obtaining RF windows capable of coupling the output power from the vacuum envelope to the  load. Other factors limiting large powers are the difficulty of operating with high voltages, of  dissipating heat in the collector, and of obtaining sufficient cathode emission current. 
 9, no. 3, pp. 364-380, 1952; also reprinted in Proc. 
 BER OF AMPLITUDE NOTCHES WITHIN THE SWEEP  THEREBY ENABLING THE RADAR TO SWEEP AT ZERO AMPLITUDE ACROSS NARROW 
          
 However, Lovell states that by the tim e he had returned to TRE in Malvern that evening, Air Chief Marshal Sir Arthur Harris (C-in-C Bomber Command) hadtelephoned the Prime Minister and had the decision reversed. In the copy of the minutes [ 1] held in the National Archives, in an RAF ﬁle folder relating to ASV Mk VI Policy, the section on ‘3 cm Equipment ’h a sb e e nd r a w nt h r o u g hi np e n c i l , doi:10.1088/978-1-6432-7066-1ch5 5-1 ªMorgan & Claypool Publishers 2018. in conjunction with various other contem poraneous comments in the margins on other matters. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 19.48  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 166. 
 For instance, indenial ofthe foregoing definitions, the mechanical category includes the conical scans that aremechanized bythe circular motion ofapoint feed around thefocus ofafixed paraboloid. Anelectri- calscan isfrequently used toproduce arapid sector scan ofsmall angular amplitude. 9“8. 
 56. A Hriel Description of the ASR-8 Airport Surveillance Radar. Tc~.~rrs I)tst~irn~~.trrs, Itrc.., SPO5A-I:.( i76. 
 [ CrossRef ] 14. Friedman, K.S.; Li, X.; Pichel, W.G.; Clemente-Colon, P . Eddy detection using radarsat-1 synthetic aperture radar. 
 PLUS 
 Roy. Soc., vol. A109, p. 
 When direct-path phase locking is used by a bistatic SAR, the required motion-compensation phase shift (to track the target phase) must correct for rel- ative motion between transmitter and receiver. When matched stable clocks are used, this correction is not required.133 Either time or phase errors can dominate synchronization requirements, de- pending upon the range and doppler accuracies needed. While all these require- ments usually can be met, implementation is more complicated, time-consuming, and costly when compared with a monostatic system, which uses one clock for both time and phase synchronization. 
 PULSE CANCELER FOR  HARD 
 Ifthemirrorisdouble-sided, thetimesbetween observations correspond to ~thandithofarevolution. Threerenectors canbeusedinsteadoffourtoproduce auniform targetobservation rate, ifthemirrorisdouble-sided. Twotargetobservations perrotation ofthemirrorareobtained, 'Jutthescanning isnotcontinuous. 
 20.4«, which shows a maximization of the sensitivity factor for a beam spacing between Aw = 0.8 and Aw = 0.9. It can be shown analytically (for gaussian beam shapes) that the optimum spacing between beams is Aw = 0.85. It is also significant to note that the valid range of angular (w-space) coverage for the sequential-lobing technique using uniform illuminated sum beams is approximately 2 - Aw, where Aw is the beam step size between transmission in w space. 
 Wheeler, H. A.: A Systematic Approach to the Design of a Radiator Element for a Phased-Array  Antenna, Proc. IEEE, vol. 
 Two of the more  10,000 r-r-tTTT ! 11  ...  CJ.>  0. 0. 
 SHELF PROCESSING CIRCUITRY  CAN READILY OUTPERFORM SCANNING AND LOBING SYSTEMS 4HE MONOPULSE TECHNIQUE ALSO HAS AN INHERENT CAPABILITY FOR HIGH 
 306--311.  48. Edgar, A. 
 Ingeneral, avoltage-sensitive element, con- sisting ofasolenoid coil and amovable armature, isconnected toa multiple contactor. Movement ofthe armature from the closed tothe open position progressively short-circuits steps ofresistance connected tothecontacts. Itisnecessary tochoose the resistance steps withthe field-excitation characteristic ofthe alternator inmind, sothat each progressive step ofresistance produces anapproximately equal change ofoutput voltage. 
 (ILL "OOK  #OMPANY     & % .ATHANSON   2ADAR $ESIGN 0RINCIPLES  ND %D  .EW 9ORK -C'RAW 
 The voltage difference between L and Mf  (the condenser terminals) is the same as at the start.  This state marks the occurrence of the ‘flip’ action.  The valve would remain in this new stable state if C  had no tendency to discharge. 
 Tlie extetided ranges during ducting conditions mean that ground clutter is likely to be present  at lotigcr ranges. 'Tliis cat1 pitt a severe burden on some MTI radars that are designed on the  assillnptiori tliat clirtter will not appear beyond a certain range. This will be particularly bad  with radars wliich cannot cancel second-time-around clutter, such as those with pulse-to-pulse  staggered pulse repetitioti frequencies or those which use tnagtietroti transmitters with random  startirig pliase pitlse to pulse. 
 Many fan-beam air-search radars  employ this type of pattern. A constant echo signal with range, however, is probably not as  important an application of the cosecant-squared pattern as is achieving the desired elevation  coverage in an efficient manner. Shaping of the beam is desirable since the needed range at  high angles is less that at low angles; hence, the antenna gain as a function of elevation angle  can be tailored accordingly. 
 SCAN FOR BISTATIC RADARS AND RADAR HITCHHIKERS AND     NONCOOPERATIVE 2& ENVIRONMENTS FOR PASSIVE BISTATIC RADARS 4HESE PROBLEMS AND THEIR POTENTIAL REMEDIES ARE DETAILED NEXT "EAM  3CAN 
 AES-10, p. 292, March 1974. 23. 
 34 FM-CW probing scatterometer measurements of a  corn plant at 30°. The solid curve is the full plant; the dot-dash curve,  leaf 1 removed; the dotted curve, leaf 2 removed. ( after L. 
 6. ISAR Signal Processing and Asteroid Image Reconstruction 6.1. Power Budget Since the asteroid’s ISAR signal distinguishes with a low signal power density on the Earth’s surface, long observation times will essentially enhance the signal to noise ratio (SNR), which can be deﬁned by the modiﬁed radar equation [ 29] SNR =S·ΔF·G·λ2·σ·Tint·n·N 4·π2(R0/prime)2kB·Ts(7) where Sis the spectral ﬂux density of the asteroid’s signal on the Earth measured in⎭bracketleftBigW m2·Hz⎭bracketrightBig ; G=q⎭parenleftbiggπ·Dpr λ⎭parenrightbigg2 is the parabolic reﬂector antenna gain; Dpris the diameter of the parabolic reﬂector; qis the eﬃciency factor which is around 0.5 to 0.6; σ=π3·D4 4·λ2is the asteroid’s radar cross section; kB=1.38×10−23⎭bracketleftBigW Hz·K⎭bracketrightBig is the Boltzmann constant; Dis the asteroid’s diameter; R0/primeis the distance to the asteroid’s mass center at the moment of imaging; Ts=410Kis the receiver noise temperature; 110. 
 SOLID-STATE TRANSMITTERS  11.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 Transmit/Receive Switching.  (1) For switching applications, the FET design  should be chosen such that the ratio of OFF-ON resistance of the FET is kept as high as  possible. The channel length largely determines the ON resistance and hence the inser - tion loss of the device. 
 VI is given in a TRE report [ 1], dated April 1944. The introduction of ASV Mk. III into Leigh Light Wellingtons (see chapter 2, section 2.2.6) early in 1943 succeeded completely in countering the U-boats that were listening for transmissions on 1.5 m (using the Metox receiver [ 2]). 
 FREQUENCY CHARACTERISTIC 4HE ALTERNATIVE CLASS OF ANTENNAS  SUCH AS LOG PERIODICS  HAVE WIDEBAND FREQUENCY CHARACTERISTICS BUT NONLINEAR PHASE 
 Levine, “A new technique for increasing the flexibility of recursive least squares smoothing,”  Bell System Technical Journal , pp. 819–840, 1961. 73. 
 16.11] MODIFICA TIO.VS A,YD ADDITIONS 609 azimuth gear train that follows the rotation ofthe antenna mount, and the information generator. The last-named unit contains the range- mark generator (which produces signals 10statute miles apart, with every fifth one ofgreater magnitude than the others), acalibrating unit fortherange-mark generator, and aunit that generates from anazimuth synchro signal the sawtooth voltage required toprovide the azimuth sweep fortheB-scopes used with theset. Azimuth marks 10°apart, with every third mark more intense, are generated inthe power console bymeans ofaphotoelectric device like that shown inFig. 
 vol. AP-4.  pp. 
 REPORTED TARGET )T IS IRONIC THAT THE VERY TARGETS THAT MAY BE HIDDEN IN CLUTTER ARE SMALLER VESSELS THAT DO NOT MANDATORILY CARRY !)3 !LSO  A #LASS " SYSTEM ONLY TRANSMITS ONCE EVERY  SECONDS AT A MAXIMUM AND SO WILL BE LESS USEFUL FOR AIDING RADAR EVEN THOUGH IT CAN USEFULLY ALERT NAVIGATORS THAT A SMALL TARGET IS PRESENT 4HE USE OF !)3 AS AN  AID 
 Ifthe voltage changes take place slowly, without transients, they can beelimi- nated bymeans ofinduction regulators, with automatic ormanual con- trol; tapped autotransformers, manual orservo-driven; or(for small loads) variacs. For example, consider theuseofcommercial power bya remote beacon station served byaline shared with other power users. Asnight falls, increasing load ontheline lowers thevoltage atthebeacon. 
  !%3! RADAR FOR THE &! 
 pp. 185-189, October, 1977.  47. 
 A wide bandwidth is needed in order to obtain  good range resolution. The lower frequencies are needed to allow the propagation of  radar energy into the ground. (Even so, the loss in propagating through typical soil  is so high that the ranges of a simple mobile GPR might be only a few meters.) Such  ranges are suitable for locating buried power lines and pipe lines, as well as buried  objects. 
 June,1974. 74.Gunn,K.L.S..andJ.S.Marshall: TheDistribution withSizeofAggregate Snowflakes, J.Melear.. .vol.15,pp.452-466, 1958. 
 ( Photo courtesy of University Corporation  for Atmospheric Research ©  2007 , Boulder, CO ) ch19.indd   37 12/20/07   5:39:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 
   2!$!2 #2/33 3%#4)/.   £{°Î£ 4EST RANGES DESIGNED TO EXPLOIT THE MULTIPATH EFFECT MAY BE ASPHALTED TO IMPROVE  THE GROUND REFLECTION  ALTHOUGH MANY RANGES ARE OPERATED OVER NATURAL SOIL 0AVING THE  RANGE ENSURES UNIFORMITY IN THE CHARACTERISTICS OF THE GROUND PLANE FROM DAY TO DAY AND EXTENDS ITS OPERATIONAL USEFULNESS TO HIGHER FREQUENCIES THAN MIGHT OTHERWISE BE POS 
 12.28  12.7 Scattering Coefficient Data  .....................................  12.35  Effects of Roughness, Moisture Content, and  Vegetation Cove r  .............................................  12.35  Soil Moisture  ...................................................... 
 However, theusualphotograph ordrawing ofaphased-array radar seldomrevealstheamount ofelectronic equipment behindthearrayfacethatisrequired to makeitausefulradar. Another oftheadvantages sometimes claimed foranarrayradaristhatitiscapableof performing morethanonefunction simultaneously; forexample, itcandosurveillance ofa volumeaswellastrackindividual targets.Themultifunction attribute ofanarrayradarhas. TtlE EI.FCTRONICA1.I.Y STFERftL) PHASED ARRAY ANTENNA IN KALIAK 337  been of considerable interest, but it can also be a serious liability in some applications. 
 If we assume that s 0 is essentially constant, the gain is constant, the pulse is rectan - gular, and the difference in range across a resolution element is negligible, the expres - sion for s 0 becomes  σπ θ λ φ03 3 2 0 04=P R P G rr t R( ) sin (16.20) where rR is the short-range resolution. Janza has reported details of calibration problems with a range-measuring pulsed  radar scatterometer.87,88 CW-Doppler Scatterometers.  A convenient way for an airborne measurement  is to measure the scattering coefficient at many angles simultaneously with a CW sys - tem in which the relative velocities corresponding to different angles are separated by  separating their doppler frequencies. 
 4.11, are more typ- ical for modern high-power TWTs for radar systems. The several different volt- ages needed for the depressed collectors add complexity to the HVPS, but for- tunately these voltages need not be as well regulated as the main beam voltage. Twystrons. 
 7. Normally, 6 is either 0° or 180° when the radar is properly adjusted, and the only purpose of the phase-sensitive characteristic of the detector is to provide a plus or minus polarity corresponding to 0 = 0° and 0 = 180°, respectively, giving direction sense to the angle-error-detector output. In a pulsed tracking radar the angle-error-detector output is bipolar video; that is, it is a video pulse with an amplitude proportional to the angle error and whose polarity (positive or negative) corresponds to the direction of the error. 
 Note also that the clutter doppler spread of a radar  wliicll actually radiated a carrier frequency Aj-would be less than that of a radar at carrier  frequency ,fb . by the amount A/%fb. The two-frequency MTI might have the blind speeds of a  MTIANDPULSE DOPPLER RADAR147 adaptively. 
 Illustrated is the effect of non- linearity.INPUTOUTPUT . O (^PrCT° = (12.19) P1^2 J [/WG,2/fl4] dA Illuminated area Proper scattering measurements demand an accurate and complete measure- ment of antenna gain Gr This can be a very time-consuming and expensive pro- cess, particularly when the antenna is mounted on an aircraft or other metallic object. Nevertheless, complete patterns are a must for good scatter measure- ments. 
 7.8 Planar-array-element geometry and phasing.PHASE AT mnth ELEMENT IS mTxs -UiTy5 TXS= ^ Sine cos0 T = i^y sine sin0* A . FIG. 7.9 Projection of points on a hemisphere onto the plane of the array. 
 If the reflector is illuminated with a simple four-element feed, a conflict generally  arises between the goals of high sum-beam efficiency and high difference-beam slope  from the monopulse comparator. The former requires a small overall feed size, whereas  the latter requires large individual feeds (Figure 12.29). Numerous design methods  have been devised to overcome this problem, as well as the associated high difference  pattern sidelobes. 
 Remote Sens. 2014 ,93, 40–48. [ CrossRef ] 2. 
 DAY REPEAT 3EVERAL YEARS AFTER THE LAUNCH OF 4ERRA3!2 
 The characteristics of the MAMIS -CFAR are quite similar to those of the  CASH- CFAR. For the CFAR -handling of block interference and of point - and extended ta r- gets, in analogy with the CASH -CFAR a = A*L/2 - L - 1 and b = A*L/2 - 1 are valid.   12.1.7  Quality of the CFAR Threshold and CFAR Loss   Now the quality of the several CFAR thresholds will be compared. 
 ctiap. 23 of" Radar Handbook." M. I. 
 A possible solution to this difﬁculty is to exploit shorter wavelengths, in order to obtain high azimuth resolution compact systems [ 15], on the other hand, by reducing the transmitted wavelength, the operating range also decreases accordingly. From these considerations, it emerges that to reach a manufacturable GB-InSAR MIMO, the future developments will require a careful trade-off analysis between complexity and performances of the available technologies. Author Contributions: Conceptualization, A.M., F.C. 
 POWER KLYSTRON AND THE TRAVELING WAVE TUBE 474  ARE EXAMPLES OF WHAT ARE CALLED  LINEAR BEAM TUBES !T THE HIGH  POWERS OFTEN EMPLOYED BY RADARS  BOTH TUBES HAVE SUITABLY WIDE BANDWIDTHS AS WELL AS GOOD STABILITY AS NEEDED FOR DOPPLER PROCESSING  AND BOTH HAVE BEEN POPULAR 4HE SOLID 
 When the PRF is high, so that many range ambiguities occur, the target range delay may be considered to be random from scan to scan, with a uniform distri- bution over the interpulse period. An approximate measure of performance in this case is found by first computing a detection curve averaged over target am- biguous ranges from zero to the range corresponding to the interpulse period. The loss is equal to the increase in signal-to-noise ratio required to obtain the same probability of detection with eclipsing or straddle as in the case when the transmit pulse is received by a matched gate with no straddle. 
 The third bistatic RCS region, forward scatter,  occurs when the bistatic angle approaches 180 °. When b = 180 ° Siegel66 showed,  based on physical optics, that the forward-scatter RCS, sF, of a target with silhouette  (or shadow) area A is  sF = 4p A2/l2 (23.16) where l, the wavelength, is small compared with the target dimensions. The targets  can be either smooth or complex structures and, from the application of Babinet’s  principle, can be totally absorbing.70,75 For b < 180°, the forward-scatter RCS rolls off from sF. 
 MONOSTATIC  BISTATIC  AND FORWARD SCATTER %ACH REGION IS DEFINED BY THE BISTATIC ANGLE 4HE EXTENT OF EACH REGION IS SET PRIMARILY BY THE TARGETS PHYSICAL CHARACTERISTICS 0SEUDO 
 2.2 Reflection on Perfect Conducting Bodies   The behaviour of reflecting objects is demonstrated on perfect conducting bodies. On conducting  bodies certain field conditions are enforced, which are signified as boundary cond itions:  - Upon perfect conducting surfaces there can exist no tangential electrical field strengths:   € Etan≡0 (1.15)  - For frequencies in the microwave range there exists an extreme Skin Effect and consequently  the penetration depths of all fields disappear.  Therefore only tan gential magnetic field comp o- nents appear on conducting surfaces. 
 The ISLR along the range direction is −9.8464. The PLSR along the azimuth direction shown in Figure 12bi s−13.2602. The ISLR along the azimuth direction is −9.8962. 
 Finally, components such ascondensers and coils become smaller asthe frequency israised, adistinct advantage inlightweight airborne radar sets. Ontheother hand, there areatleast two very cogent reasons forfavoring alow intermediate frequency: (1)the noise figure ofthei-famplifier issmaller atlower frequencies, and (2)manufacture and maintenance isconsiderably simplified because variations intube and wiring capacitances, aswell asintuning inductances, affect theover-all receiver response much less; Thus the choice ofanintermediate fre- quency isacompromise. FrequenciesII of30Me/see and 60Me/see have been chosen for most ofthe present-day ~ radar sets. 
 414-464, September, I 968.  78. Dillard, G. 
 10.7] PULSER CIRCUITS 359 tude ofthe first reflection would beonly 7per cent ofthat ofthe main pulse, and thepower involved inthat reflection isonly 0.5percent ofthat ofthemain pulse. Forall practical designs, amismatch of20t030 per cent isacceptable from thestandpoint ofenergy loss. Design considera- tions forthebest useofavailable components usually make itpreferable tokeep the impedance 20small, generally about 50ohms. 
 1973, pp. 257 262. IEE Conference  Puh. 
 STC decreases the sensitivity of the radar at short range  and then increases sensitivity, usually using a fourth-power law, as range increases.  This has the effect of not permitting detection of targets with apparent radar cross sec - tions of, say, less than 0.1 square meter. Figure 2.96 shows how effective STC can be  against birds. 
 POINTING DIRECTION MAY ADD OR SUBTRACT  DEPENDING ON THE DIRECTION IN WHICH THE BEAM HAS BEEN SCANNED 4HE WORST CASE WILL BE CONSIDERED HERE.   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°{£ 7ITH A CHANGE IN FREQUENCY  A NONDISPERSIVE TRANSMISSION LINE HAVING FREE 
 Installed systems normally extract the raw data  from the existing 9 GHz radar and perform wave processing and display functions on  a separate processor/display system. Spectrum analysis of this type can also detect oil  slicks17 because they reduce the amplitude of sea surface capillary waves. Such sys - tems can be valuable on vessels assisting with clean-up operations and also for early  detection of spills from oil rig operations. 
 11.3. This is followed by a treatment of the ambiguity function and its effect on waveform  design. Pulse compression waveforms and processing are discussed in Sec. 
 Inspiteofthese limitations, theHFregionofthespectrum isofspecialinterestforradarbecauseofitsunique property ofallowing propagation tolongdistances beyond thecurvature oftheearthby meansofrefraction fromtheionosphere. Asinglerefraction allowsradarrangestobeex­ tendedtoalmost4000km.ThetargetsofinteresttoHFover-the-horizon (OTH)radararethe. same as those of interest to microwave radar and include aircraft, missiles, and ships. 
 I I  I I  I I  Time-+- (cl Angle  (bl ' \  \  I  I  I  I  I  I \  I  \  I  \  \ /-,  J / \  ..  Figure 5.1 Lobe-switching antenna  patterns and error signal (one dimen­ sion). (a) Polar representation of  switched antenna patterns; (b) reel·  angular representation; (c) error signal. 
 Since T]1 does not equal T)2, different weighting constants are required for each pulse pair. The values of kl for the quadrature correction of the first pulse pair, k2 for the quadrature correction for the second pulse pair, [, for the in-phase correction for the first pulse pair, and [2 for the in-phase correction for the second pulse pair are optimized by minimizing the integrated residue power over the significant portion of the antenna pattern, usually chosen between the first nulls of the main beam. Figure 16.17 shows the sum and difference main-beam patterns for an apertureSUMDIFFERENCEGAIN (dB) . 
 DESIGNED MATCHED  RADIATING ELEMENT   COSP  FOR VALUES UP TO  SOME  OR  n !T GREATER ANGLES  THE ELEMENT PATTERN HAS VALUES THAT ARE GREATER THAN  THOSE GIVEN BY  COSP AND THAT ARE A FUNCTION OF THE TOTAL NUMBER OF ELEMENTS 3CANNED ,INEAR !RRAYS  4HE PATTERN OF THE ARRAY MAY BE STEERED TO AN ANGLE  P  BY APPLYING LINEARLY PROGRESSIVE PHASE INCREMENTS FROM ELEMENT TO ELEMENT SO THAT  THE PHASE BETWEEN ADJACENT ELEMENTS  DIFFERS BY  O SK  SIN P %QUATION  IS THEN  MODIFIED  GIVING THE NORMALIZED ARRAY FACTOR OF A UNIFORMLY ILLUMINATED ARRAYS AS&)'52%  !RRAY FACTOR WITH .    ELEMENTS .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°£Î   %.S .SA SIN    SIN SIN   SIN    SINPPP P 
 This data indicates the median diurnal frequency variations required for a particular path: more than 2:1 in winter and somewhat less in summer. Day-to- day variability will impose greater extremes. In this section the predictable and random variability of the transmission path has been indicated. 
 In order to preserve this SNR growth, the number of bits used  to represent the filter output might need to increase. If the filter reduces the band - width of the data by a factor R without affecting the signal of interest, then the SNR  increase in dB is given by 10log10R. In our example, a 2× reduction in bandwidth  results in approximately a 3 dB increase in SNR. 
 TO 
 Mensa, U.S.  Navy Pacific Missile Test Center .) ch14.indd   34 12/17/07   2:47:26 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 280INTRODUCTION TORADAR SYSTEMS shape,provided thephaseateachelementjsthatneeded togiveaplanewavewhenthe radiation fromallthe.elements issummed inspace.Anarraywhosedements aredistributed onanonplanar surfaceiscalledaconformal array. Anarrayinwhichtherelativephaseshiftbetween elements iscontrolled byelectronic devicesiscalledanelectronically scanned array.Inanelectronically scannedarraytheantenna elements, thetransmitters, thereceivers, andthedata-processing portions oftheradarare ortendesigned asaunit.Agivenradarmightworkequallywellwithamechanically positioned array,alens,orareflector antenna iftheyeachhadthesameradiation pattern,butsucha radarcouldnotbeconverted efficiently toanelectronically scanned arraybysimplereplace­ mentoftheantenna alonebecause oftheinterdependence ofthearrayandtheother portions oftheradar. Radiation pattern.811Consider alineararraymadeupofNelements eqllallyspaceda distancedapart(Fig.8.1).Theelements areassumed tobeisotropic pointsourcesradiating uniformly inalldirections withequalamplitude andphase.Although isotropic elements are notrealizable inpractice, theyareausefulconceptinarraytheory,especially forthecomputa­ tionofradiation patterns. 
   2!$!2 #2/33 3%#4)/.   £{°£Ç $IFFERENTIAL %QUATIONS  -AXWELLS FOUR DIFFERENTIAL EQUATIONS CONSTITUTE A SUC 
 and phase) can be employed for target classificati~n.~~  EXTRACIION 01'INFORMATION ANDWAVEFORM DESIGN435 majorscattering centers.Fromthisrangeprofile,anestimate ofthetargetsizecanbemade. Theprofileobtained bytheradaristheprojection inthedirection ofpropagation. Acomplete "image"ofthetargetwouldrequiremultiple looksfromdifferent directions.Ifthetrajectory ofthetargetisknownfromthemeasurement ofthetargettrack,itispossible toinferthe aspectoftheradarprojection. 
 SCAN REPRESENTS A HORIZONTAL PLANE  X  Y  AT A GIVEN DEPTH  Z  !LTERNATIVELY  THE '02 MAY BE DESIGNED TO PROVIDE AN AUDIBLE WARNING OF TARGET  PRESENCE WHILE THE '02 IS MOVED 4HE '02 IMAGE OF A TARGET IS VERY DIFFERENT FROM ITS OPTICAL IMAGE BECAUSE THE  WAVELENGTHS OF THE ILLUMINATING RADIATION ARE SIMILAR IN DIMENSION TO THE TARGET 4HIS RESULTS IN A MUCH LOWER DEFINITION IN THE '02 IMAGE AND ONE THAT IS HIGHLY DEPENDENT ON THE PROPAGATION CHARACTERISTICS OF THE GROUND 4HE BEAM PATTERN OF THE ANTENNA IS WIDELY SPREAD IN THE DIELECTRIC AND THIS DEGRADES THE SPATIAL RESOLUTION OF THE IMAGE  UNLESS CORRECTED 2EFRACTION AND ANISOTROPIC CHARACTERISTICS OF THE GROUND MAY ALSO DISTORT THE IMAGE &OR SOME  LONGER 
 H. Hibbs: Organ-pipe Radar Scanner, Electronics, vol. 25, pp. 
 MATES HAS PRIMARY SIGNIFICANCE $UAL POLARIZATION MEASUREMENTS  AT MULTIPLE WAVE 
 |  Quite a number of these important radar circuits were  devised for other purposes long before radar came into  being, and prior to 1930 they were only of academic  interest. Now they have a direct practical application,  despite the fact that the conventional radio man classifies  them as ‘impossible.’  . VII, PICTURE ON THE TUBE  ANGE-AMPLITUDE, OR TYPE A, DISPLAY ON THE  CRT of a radar receiver would be of very little use  with many modern systems, as the information it gives  is not sufficiently accurate, nor can it be deciphered  sufficiently speedily. 
 SPACE CONDITIONS AND  % IS THE  MAGNITUDE OF THE FIELD TO BE INVESTIGATED AT THE SAME POINT.   4(% 02/0!'!4)/. &!#4/2  &0  ). 4(% 2!$!2 %15!4)/.   ÓÈ°£x 4HE PROPAGATION FACTOR IS A DESIRABLE QUANTITY SINCE IT IS AN IDENTIFIABLE PARAMETER IN  MOST RADAR EQUATIONS !S STATED EARLIER  IT ALSO CONTAINS ALL THE INFORMATION NECESSARY TO  ACCOUNT FOR NATURAL ENVIRONMENTAL EFFECTS 4HUS  IF THE FUNCTIO NAL FORM OF & IS KNOWN   THEN THE PROPAGATION LOSS AT ANY POINT CAN BE DETERMINED BECAUSE THE CALCULATION OF THE FREE 
 POLARIZATION DOPPLER RADAR FOR CLOUD AND PRECIPITATION STUDIES v  * #LIM !PPL -ETEOROL    VOL   PP n    2 ,HERMITTE  h!  
 ........................  4  Signal Routing  ................................ ................................ 
 These factors can degrade the tracking accuracy by causing the  antenna beam to fluctuate in a random manner about the true target path. These noiselike  fluctuations are sometimes called tracking noise, or jitter.  A simple radar target such as a smooth sphere will not cause degradation of the angular­ tracking accuracy. 
   
 vol. AP-23. pp. 
 A block diagram of a CW radar using  the third harmonic (J3 term) is shown in Fig. 3.17. The transmitter is sinusoidally frequency-  modulated at a frequency fm to generate the waveform given by Eq. 
 The bandpass filter can be designed with a variable low-frequency cutoff that can be  selected to conform to the prevailing clutter conditions. The selection of the lower ciitoff might  be at the option of the operator or it can be done adaptively. A variable lower cutoff might be  advantageous when the width of the clutter spectrum changes with time as when the radar  receives unwanted echoes from birds. 
 92. R. K. 
 “Performing electronic countermeasures in the United States and Canada,” U.S. Navy  OPNA VINST 3430.9B, October 27, 1969. Similar versions issued by the U.S. 
 It is well worth while considering the history of this  development, for it is to the exclusive credit of Britain,  and is a development parallel with that of the harnessing  of atomic power. Professor M. L. 
 Theregionsofbeamformation, RFinteraction, andbeamcollection are separate andindependent intheklystron. Eachregioncanbedesigned tobestperform itsown particular function independently oftheothers.Forexample, thecathode isoutsidetheRF fieldandneednotberestricted tosizessmallcompared withawavelength. Largecathode area andlargeinterelectrode spacings maybeusedtokeeptheemission currentdensities and voltagegradients toreasonable values.Theonlyfunction ofthecollector electrode inthe klystron istodissipate heat.Itcanbeofashapeandsizemostsuitedforsatisfying theaverage orpeakpowerrequirements without regardforconducting RFcurrents, sincenonearc present. 
 IN 
 VI, with the transmitter power divided equally between the two horns, providing a single beam with no offset squint. In the auto mode, the response from a target inthe beam would depend on its azimuth offset from the beam centre. The target return signal was synchronised with the position of the splitter switch and used to drive the Figure 4.8. 
 SYSTEM PERFORMANCE VARIES FROM THAT OF A TRIPLE CANCELER TO A PERFOR 
 GYRATION ALONG THE ANGLE COORDINATE  &)'52%     !NGLE 
 CALLED CONFOCAL REFLECTOR SYSTEM n SHOWN IN &IGURE  4HIS SYSTEM EMPLOYS TWO PARABOLIC REFLECTORS  A  MAIN AND A SUB  THAT SHARE A COMMON FOCAL POINT 4HE OPTICS OF THIS SYSTEM IS DESIGNED SUCH THAT A PLANE WAVE SOURCE  SAY FROM AN ARRAY  IS FIRST CONVERTED TO A SPHERICAL WAVE AT THE SUBREFLECTOR 4HEN  UPON REFLECTION FROM THE SUBREF LECTOR  THE FEED ENERGY  CONVERGES AT THE COMMON  FOCUS AND DIVERGES  AGAIN AS A SPHERICAL  WAVE BEFORE FINALLY  REFLECTING FROM THE MAIN REFLECTOR 4HE CONFOCAL SYSTEM HAS SEVERAL INTERESTING PROPERTIES  TIED TO THE MAGNIFICATION  FACTOR -  -   F -  F3    WHERE F- AND F3 ARE THE FOCAL LENGTHS OF MAIN AND SUBREFLECTORS  RESPECTIVELY 4HE FIRST  PROPERTY SHOWS THAT THE SYSTEM IS ESSENTIALLY A FEED SOURCE MAGNIFIER 4HE REFLECTOR  GAIN  'R  IS DESCRIBED BY   'R y 'F  r -  r COSPR     WHERE 'F IS THE GAIN OF THE FEED ARRAY AND  PR IS THE SCAN ANGLE OF THE REFLECTOR SECOND 
 This is plotted in Figure 2.24 for rain and  for wooded hills with a 40 knot wind. This limitation on the MTI improvement factor  is independent of the type of canceler employed. Time-Varying Weights. 
 STRAINED TO THE UNIT CIRCLE 4O MOVE THE ZEROS OFF OF THE UNIT CIRCLE  WHICH MAY BE DONE  TO CONTROL THE FLATNESS OF THE FILTER PASSBAND RESPONSE  REQUIR ES A CONFIGURATION SIMILAR  TO THE ELLIPTIC FILTER CONFIGURATION SHOWN IN &IGURE  LATER IN THIS CHAPTER 4HE TRIPLE 
 the wave scattered from the sea surface are out of phase and produce destructive interference.  (The interference region is not well defined at the higher microwave frequencies plotted in  Fig. I .1 . 
 -ONOSTATIC 2#3 2EGION  4HE #RISPIN AND 3IEGAL MONOSTATIC 
 Movable electronic indices appear onthe indicator only when the cathode-ray beam isonaparticular part ofthe tube face. Tosetan index onanecho, itisessential tobeable toobserve theresults ofmoving theindex. Ifthescan israpid, theo~erator has freauent chances todo so,but ifitisslow hecannot cor- rect anerror forseveral seconds. 
 A2Pby2qelementarray(p, qareintegers) requires2P+2qnetworks toachieve2P+qbeams.Othermethods ofusingButler networks inplanararraysarepossible. Shelton,91 forexample, describes atechnique for generating multiple beamsinhexagonal planararrayswithtriangular spacing. fheButlernetworks inthissectionwereassumed touse3-dBdirectional couplers witha 900phasedifference between thetwoequaloutputs. 
 The oscillator ofFig. 13.37 canbeofany type satisf ying theparticular precision requirements. The original sinusoid isamplified and clipped toproduce asymmetrical square wave ofthe same frequency. 
 The frequency-response [unction, denoted H(f ), expresses the relative amplitude and  phase of the output of a network with respect to the input when the input is a pure sinusoid.  The magnitude I H(f) I of the frequency-response function is the receiver amplitude passband  characteristic. Ir the bandwidth of the receiver passband is wide compared with that occupied  by the signal energy, extraneous noise is introduced by the excess bandwidth which lowers the  output signal-to-noise ratio. 
 [ CrossRef ] 19. Luo, Q.L.; Perissin, D.; Lin, H.; Zhang, Y.Z.; Wang, W. Subsidence monitoring of tianjin suburbs by terrasar-x persistent scatterers interferometry. 
 This shortcoming limits its use to low-density aircraft situations where it is unlikely to encounter two aircraft ap- pearing at the same range and azimuth but at different heights. The Japanese have developed a radar based on phase interferometry to find height in air traffic control applications,12 but it also does not have resolution in the elevation dimension. The concept employs a set of four horizontal line arrays vertically displaced in a staggered fashion about a conventional 2D reflector-type antenna. 
 F.XTRA('TION OF INFORMATION AND WAVEFORM DESIGN 403  The echo signal y(t) is compose<l of signal and noise, s(t -T0) + n(t), where s(t T0) is  the echo signal in the absence of noise. The contributions due to signal s0 and noise n0 at the  output of the low-pass filter may be expressed as  ( 11.6)  110(TR) f g(t -Tn)n(t) dt ( 11. 7)  Defining L\ TR = TR -T0, the form of the output s0(L\ TR) with an optimum gating signal  should be an odd function. 
 The Doppler rate has great inﬂuence on the image quality and a little error will result in image defocusing and decreased resolution. The degree of defocusing is directly related to the Doppler rate shift [ 5]. The experimental results of ship05 are shown in Figure 16. 
 ING MARITIME RECONNAISSANCE MISSIONS )N   TYPICAL IMAGERY FROM 3EASAT 3!2 SHOWED SEVERAL FEATURES THAT MADE THE 3!2 A POWERFUL MARITIME SURVEILLANCE SENSOR 4HE SHIPS AND THE WAKES PRODUCED BY THE SHIP MOTION WERE IMAGED 4HE SHIP IMAGE A BLOB  APPEARED DISPLACED FROM ITS WAKE DUE TO THE DOPPLER SHIFT CAUSED BY THE SHIPS MOTION RELATIVE TO THE SPACECRAFT (OWEVER  THE SHIPS POSITION AT THE TIME OF IMAGING AND ITS COURSE COULD BE DETERMINED FROM THE WAKE 4HE SHIP SPEED CAN BE CALCULATED TOO BY THE DISPLACEMENT OF THE SHIP FROM ITS WAKE !LL THIS INFORMATION IS OBTAINABLE ONLY IF ENOUGH 3.2 IS AVAILABLE FOR THE IDENTIFICATION OF THESE IMAGE FEATURES EITHER BY A HUMAN OPERATOR OR AN AUTOMATIC PROCESSOR 4HERE EXISTS  THEREFORE  A POTENTIAL VULNERABILITY TO 3!2 IN THE MARITIME SURVEILLANCE APPLICATION IF A HIGH LEVEL OF BACK 
 By integrating the two-sided tails of the gaussian and exponential spectra, outside  a multiple, k, of the standard deviation of the spectra, a rough, but conservative,  estimate can be found of how wide the MTI notch must be to achieve a required  improvement factor I. Such a curve is shown in Figure 2.15 based on the clutter  spectra shown in Figure 2.14. Although this approach would only be strictly correct  for an ideal MTI filter with a step-function passband, it can serve as a preliminary  guideline for the MTI filter design. 
 PATH  IS NEARLY ALWAYS THE DOMINANT 2&) SOURCE -ULTIPATH SIGNALS FROM THAT TRANSMITTER ARE LESS SEVERE BUT CAN ALSO CONTRIBUTE TO 2&) 2&) OVER THE DIRECT 
 Rheinstein, J.: Backscatter from Spheres: A Short Pulse View, IEEE Trans., vol. AP-16, pp. 89-97,  January, 1968. 
 After the time of  the ~naximum range return lias elapsed, the phase shifters can be set for the next transmission.  At this tirne. the signal processor can be set to accommodate the next dwell. 
 Knittel (eds.), Artech House. Inc.. 1972, pp. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 12.4  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 Thus, the edge angle for a round reflector is  αedge=   24arctanD f (12.4) Another useful parameter is the distance r from the focal point to a point on the reflector:  r fx y f= ++2 2 4 (12.5) Aperture Gain and Losses. 
 adoption of the direction cosine coordinate system. In this system the linear- phase tapers defined by the beam-steering direction (cos Ox,, cos ays) may be summed at each element so that the phasing at the mnth element is given by tymn = mTxs + nTys where Txs = (2fnl\)dx cos a^ = element-to-element phase shift in the x direction Tys = (2itl\)dy cos Ct^ = element-to-element phase shift in the y direction The array factor of a two-dimensional array may be calculated by summing the vector contribution of each element in the array at each point in space. For an array scanned to a direction given by the direction cosines cos GLXS and cos ays, the array factor of an M x N rectangular array of radiators may be written M-I Af-I F (cn* n rn<5 n, ^l - "V V 14 \J-m(Tx ~ Txs) + n(Ty - Tvs)]^aV^OS CLXS, COS OLys) — ^j ^j \/\.mn\(r m = O n = O where Tx = (2WX) dx cos ax Ty = (2WX) dy cos Oy Amn = amplitude of mnth element An array may be visualized as having an infinite number of grating lobes only one of which (namely, the main beam) is desired in real space. 
 (2)]. Many more stages would berequired toincrease this bandwidth greatly, since the gain per stage must belowered. The over-all band- width ofanamplifier consisting ofcascaded single-tuned stages isgiven approximately bytheformula Over-all bandwidth =single-stage bandwidth 1.2{n “(4) When n,thenumber ofcascaded stages, islarger than 3,this formula is quite accurate. 
 BANCE 4)$  4)$S MAY HAVE WAVELENGTHS OF HUNDREDS OF KILOMETERS AND SPEEDS UP TO  KILOMETERS PER HOUR 5NLESS THE RADAR MAKES APPROPRIATE REAL 
 VERTED TO ANALOG THROUGH A $!#  AND PASSED THROUGH A BANDPASS FILTER TO PRODUCE AN )& OUTPUT &OR LARGE UPSAMPLING RATIOS  A CASCADED 
 AVERAGING CONSTANT FALSE ALARM RATE #! 
 TERM RELIABILITY AT THE LONGER PULSE WIDTH  THE DISSIPATION IN THE TRANSIS 
 Even as early as 1944,  some attention was being given to the peacetime role of radar as a navigational aid  for commercial shipping. In 1946, an “International meeting on radio aids to marine  navigation” was held in London and attended by representatives from 23 countries.38  The meeting was chaired by Sir Robert Watson-Watt. It was seen that radar on com - mercial vessels had an important part to play in anti-collision, coastal navigation, and  pilotage decisions. 
 The angle loca - tion is the data obtained from synchros and encoders on the antenna tracking axes   (or data from a beam-positioning computer on an electronic-scan phased array radar).  In some cases, tracking lag is measured by converting tracking-lag-error voltages from  the tracking loops to units of angle. This data is used to add to or subtract from the  angle shaft position data for real-time correction of tracking lag. 
  RESEARCH AIRCRAFT ./!! HAS OPERATED TWO 8 
 WidthCoding. —Letters ofthe Morse code can betransmitted by changing thewidth ofthepulses intheproper sequence instead ofturning the pulses onand off. Beacons emitting such width-modulated replies will give adisplay onscanning radars and have theadditional slow gap code which can beread iftheseaming isstopped. 
 PULSED 474S AND  #&!S !DJACENT 
 Except for two small doppler  regions, all the PRFs are clear at maximum range, which provides maximum detec - tion and minimum loss at the design range. For some pulse compression waveforms,  the eclipsing loss is almost linear and partial overlap still allows shorter-range detec - tion. Eclipsing loss is that diminishment of received power when the receiver is  off during the transmitted pulse. 
 We shall make useoftheequation that gives themaximum detection range ofasystem asafunction ofthe system parameters. The range equation (see Sec. 2.4) can bewritten as (1) where P=pulse power a=radar cross section oftarget A=area ofantenna aperture fisadimensionless constant dependent onthe efficiency ofthe antenna aperture. 
 Its maximum average power is of the order   of several kilowatts, which is less than that required for some military applications.  ch10.indd   15 12/17/07   2:19:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 PULSE -4)  IS   HP LQW W  ¤ ¦¥³ µ´ 4646P XRP YRSIN SIN COS44P  
 However, if the correlation  time is less than a batching interval, the batch processor will yield a low Pfa without  modifications. Target Suppression . Target suppression is the loss in detectability caused by other  targets or clutter residues in the reference cells. 
 SPEED SEQUENTIAL SAMPLING APPROACH USED TO ACQUIRE 2& WAVEFORMS PRODUCES A LOW . 
 (/2):/. 2!$!2   Óä°ÈÇ 3EVERAL QUALIFIERS SHOULD BE KEPT IN MIND !T OTHER GEOGRAPHIC LOCATIONS  THE APPRO 
    PP n    * &IGA 
 D., and E. G. S. 
 12. Graham, L. C.: Stereoscopic Synthetic Array Application in Earth Resource Monrtoring, lEEE  NAECON '75 Record, pp. 
 BASED RADAR IMAGERY TO MAINTAIN SURVEILLANCE AND TO COMPILE ANNUAL STATISTICS OF DEFORESTATION 3INCE RADAR IMAGERY IS A RELIABLE METHOD OF MAPPING SLICKS ON THE OCEANS SURFACE  IT IS THE PRINCIPAL MEANS OF MONITORING  OIL SPILLS THAT MAY RESULT FROM A GROUNDED TANKER  OR A VESSEL ILLEGALLY PUMPING ITS BILGES IN A COASTAL AREA 4HE IMAGING RADAR REFERENCE   CITED EARLIER PROVIDES AN EXCELLENT REVIEW OF MANY OF THESE APPLICATIONS £n°ÎÊ  / 
 While the majority of radar engineers are familiar with cur- rent operational meteorological radars, few are aware of the advances that have been made in the past two decades. For example, doppler radar meteorology, us- ing modern digital signal-processing techniques and display technology, has moved ahead so rapidly that the United States is now planning to replace its ex- isting operational weather radar network with a next-generation doppler system (NEXRAD). This system will provide quantitative and automated real-time infor- mation on storms, precipitation, hurricanes, tornadoes, and a host of other im- portant weather phenomena, with higher spatial and temporal resolution than ever before.1 A second network of doppler radars, in airport terminal areas, will provide quantitative measurements of gust fronts, wind shear, microbursts, and other weather hazards for improving the safety of operations at major airports in the United States.1'2 Next-generation doppler radars that use flat-plate antennas, color displays, and solid-state transmitters are now available for commercial air- craft. 
 154. Nelson, E. A.: Quantization Sidelobes of a Phased Array with a Triangular Element Arrangement,  IEEE Trans., vol. 
 58. Poling, A. C.: Tellurometer Manual, U.S. 
 J. Gary, arid G. W. 
 limiter Residue ch02.indd   50 12/20/07   1:45:00 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 Stimson5 explains: “Typically, the antenna  continuously scans the region of interest...Because the integration time is limited to  the length of time a ground patch is in the antenna beam—or, if you prefer, the length  of the array that can be synthesized is so limited—the resolution is coarser than can be  achieved with a non-scanning antenna” (p. 434). Unfocused SAR. 
 PULSE BINOMIAL 
 The impact of environmental fac - tors varies widely, but some of the factors that are typically significant include thermal,  vibration, and exposure (e.g., salt, sand, water, radiation, etc.). Thermal effects, i.e.,  spatial or temporal temperature variations, are of particular concern for spaceborne  sensors that often see very significant temperature changes (greater than 100° C tem - poral or spatial variation is not uncommon). Vibration is another concern, especially  for airborne and spaceborne reflectors. 
 LEVEL MAINTENANCE 4HE SUITE OF MICROWAVE AND 2& APERTURES IN A FIGHTER AIRCRAFT MIGHT APPEAR AS  SHOWN IN &IGURE  !S MANY AS  APERTURES MAY BE DISTRIBUTED THROUGHOUT THE VEHI 
 186-192.  Sept. 25-27, 1978, IEEE Publication 78 CH 1352-4 AES. 
 a Sz  VS  Cc) C 4  D HT.  FIG. I. 
     
 ScanSAR.38–40 If swath width is the driving requirement, then azimuth resolution  can be traded for range coverage. The trick is to multiplex several burst-mode data  sets, where each set of bursts corresponds to a different range sub-swath. In this form  of burst mode, the transmitter is always “on”; the burst range sub-swath allocation  burden falls onto the antenna. 
 The statistical distribution of waveheights on the ocean surface is quite close to  gaussian, with a mean square height that can be obtained by integrating the wave - height spectrum over all frequencies (or wavenumbers). For spectra resembling those  in Figure 15.1, the rms waveheight is given approximately by  hrms = 0.005 U 2  m (15.6) FIGURE 15.1  Sea wave frequency spectra of the Pierson-Moskowitz  type, representing fully developed seas ( after W. J. 
 TRACKING SYSTEM  WITH THE SCHEDULING AND CONTROL FUNCTION OF THE RADAR IS MINOR FOR MECHANICAL ROTATING RADARS BUT MAJOR FOR PHASED ARRAY RADARS &OR MECHANICALLY ROTATING RADARS  ALL THAT IS USUALLY DONE IS THAT THE TRACKING GATES ARE FED BACK TO THE SIGNAL PROCESSOR 4HE TRACKING GATES ARE ALWAYS USED TO FACILITATE THE ASSOCIATION PROCESS AND MAY BE USED TO LOWER THE DETECTION THRESHOLD WITHIN THE GATE ANDOR MODIFY THE CONTACT ENTRY LOGIC WITHIN THE  GATE EG  MODIFY RULES GOVERNING CLUTTER MAPS  4HE INTERACTION OF THE TRACKING SYSTEM WITH A PHASED ARRAY RADAR IS MUCH MORE SIG 
 ABILITY DENSITY FUNCTIONS FOR DIFFERENT TARGET CONFIGURATIONS 4HE RANGE NOISE MEASURE 
 2 Representation of the principle parts of a traveling wave tube,  showing a helix slow-wave circuit shown for simplicityGun anodeAttenuationCollector Helix (interaction region) RF InputRF outputElectron beamHeaterCathode ch10.indd   8 12/17/07   2:19:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. The Radar Transmitter. 
 For large signal-to-noise ratios, the accuracy (rms error) of the beam-splitting and maximum-return procedures will be limited by the pulse SINGLE-PULSE SIGNAL-TO-NOISE RATIO IN dB FIG. 8.5 Detection performance of the analog moving-window detector for the no-fading case. (Copyright 1970, IEEE; after Ref. 
 INDUCED SURFACE CURRENTS MUST BE ACCOUNTED FOR SEPARATELY  JUST AS IN 5FIMTSEVS 04$ 7HEN THE DIRECTIONS OF INCIDENCE AND SCATTERING BECOME PERPENDICU 
 For details, see paragraphs on sparking, moding, noise rings, spurious RF output, and RF leakage, discussed under "Common Problems" in magnetrons (Sec. 4.2). One difference is that because RF drive is present during the voltage rise time, many (but not all) cathode-pulsed CFAs al- low a much faster voltage rate of rise than magnetrons. 
 A second method of Multiple-Target Tracking, Pause-While-Scan , particularly  applicable to ESA-based radars, is to scan in a normal search pattern, pause on  each search detection, and enter a Single-Target Track mode for a brief period. The  advantage is that the resulting range, angle, and doppler measurements are more  accurate than those made with a scanning antenna, but the time to search a volume  in space is increased. Transition-to-Track,  or Track Acquisition, is used to confirm search target detec - tions and provide improved range accuracy when needed. 
 BAND MONOPULSE CAN BE EFFICIENTLY ACCOMMO 
 Overall, the transceiver module can be made much smaller than with dis- crete components. However, there are inherent drawbacks to the MMIC approach to component de- sign. The nonrecurring engineering design cost is very high. 
 The transmitter power then follows the Curve aofFig. 5“16,and thereceiver input follows Curve bwith thetime delay depending onthe range and with the dotted part ofthe received signal rejected because the receiver isoff.1This received signal isamplified byaconventional superheterodyne receiver whose only special feature isthe derivation ofthe local-oscillator frequencY from the transmitter frequency bythe addition of30Me/see. Thk 30Me/see isthen sub- tracted inasecond detector sothat the received signal istranslated down tozero frequency. 
 88–93. 41. “Multistatic mode raises radar accuracy,” Aviation Week and Space Technology , pp. 
 ABLE TO RESORT TO THE TECHNIQUES OF LINEAR PREDICTION THEORY FOR STOCHASTIC PROCESSES  $ENOTE WITH  6 -  THE RADAR SIGNAL AT A CERTAIN RANGE BIN AND WITH  6   6  6  x  6.    THE . 
 For example, it was noticed that optical ﬂow object matches close to image block borders can be overlooked due to the inaccuracy of ﬂow vectors near the block borders. This problem can be addressed with a multigrid approach that leverages overlapping image blocks. Using this approach, if an object pair is close to the border in one block, then it will be near the center of an overlapping block. 
 114. George, S. F.: The Detection of Nonnuctuating Targets in Log-Normal Clutter. 
 The modulated signal from the second synchro ispassed through animpedance-changing cathode follower Vz,demodulated byaphase-sensitive rectifier Vt(Sec. 13.9), then smoothed byanRC-filter. The azimuth deflecting circuit is completed bythe push-pull amplifier VA, Vh,inwhich the latter tube receives itsexciting signal byvirtue ofthe common cathode and screen resist ors. 
 By the end of WWII very many thousands of ASV systems had been manufactured and RAF Coastal Command had a total establishment of over 1000 maritimereconnaissance aircraft in a wide variety of roles, but all ﬁtted with ASV radar. In this volume, I describe the main ASV radars developed in the UK during WWII for the RAF. Each radar is described in terms of its hardware, its radar characteristicsand the performance achieved. 
 or imaging. radars that utilize higl_1 resolution. Ground objects are recognized by  their shape and contrast with surroundings. 
 Second-time-around clutter echoes can be removed by use of a constant  prf. providing there is pulse-to-pulse coherence as in the power amplifier form of MTI. The  constant prf might be ~mployed only over those angular sectors where second-time-around  clutter is expected (as in the ARSR-3 of Sec. 
 MANCE IS USUALLY ACHIEVABLE ONLY WITH THE PYRAMIDAL DESIGN  %ARLY INDOOR CHAMBERS WERE RECTANGULAR IN SHAPE  AND DESPITE THE INSTALLATION OF  GOOD ABSORBENT MATERIALS ON THE WALLS  2#3 MEASUREMENTS COULD BE CONTAMINATED BY WALL REFLECTIONS 4HE MOST SENSITIVE PART OF THE ANECHOIC CHAMBER IS THE REAR WALL  WHICH RECEIVES  TO  PERCENT OF THE POWER RADIATED BY THE RADAR HENCE  THE BEST ABSORBER SHOULD BE RESERVED FOR THE REAR WALL  4HE FLOOR  CEILING  AND SIDEWALLS ALSO  CONTRIBUTE ERRORS  VIA A QUADRUPLET OF REFLECTIONS NOT UNLIKE THOSE DUE TO THE GROUND PLANE OF OUTDOOR RANGES ! REMEDY IS THE TAPERED ANECHOIC CHAMBER  WHICH ELIMINATES MOST OF THE SIDEWALL REFLECTIONS PURELY BY TILTING PORTIONS OF THE WALLS  FLOOR  AND CEIL 
 34. Ward, H. R.: Doppler Processor Rejection of Ambiguous Clutter, IEEE Trans., vol. 
 J. J. Scavullo and F. 
 POLARITY ARCHITECTURE  THAT IS  OUTLINED BELOW -AGELLAN )NNOVATIVE 6ENUS -APPER  -AGELLAN &IGURE   HAD TO FACE UP  TO TWO DRIVING MISSION RESTRAINTS COST AND DATA RATE 4HE FIRST WAS SET BY .!3! AND THE 53 GOVERNMENT BUDGET AUTHORITIES 4HE SECOND WAS SET BY PHYSICS  CONDITIONAL UPON THE DATA 
 1961.  30. Citlinnrd. 
 8. Sleator: The Theoretical and Numerical Determina­ tion of the Radar Cross Section of a Prolate Spheroid, IRE Trans., vol. AP-4, pp. 
 18.57  Reduction of Internally C aused Errors   ................  18.57  19. Radar Guidance of Missiles   ................................... 
 GROUND ECHO  16.416x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 for this purpose. Most of the spaceborne SARs that followed Seasat have been used in  soil-moisture studies.144,145,146 Vegetation.  Backscatter from vegetation depends on many parameters and var - ies widely. 
 RADAR DIGITAL SIGNAL PROCESSING  25.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 that stage ( q i from the table) to the previous value of f.  If f < 0, q i is added to f.  Otherwise, q i is subtracted from f. 
 ISTIC EFFECTS 4HE ELECTRONS FOLLOW HELICAL PATHS AROUND THE MAGNETIC FIELD LINES WHEN IN  THE PRESENCE OF AN ELECTROMAGNETIC WAVE WITH A TRANSVERSE COMPONENT OF ELECTRIC FIELD  %LECTRONS THAT LOSE ENERGY TO THE ELECTROMAGNETIC WAVE BECOME L IGHTER AND ACCUMULATE  PHASE LEAD AND THEN CATCH UP WITH THE ELECTRONS THAT GAIN ENERGY AND BECOME HEAVIER AND ACCUMULATE PHASE LAG 4HUS  ELECTRONS BECOME PHASE 
 3.10 and 3“11). The modulation isfarfrom sinusoidal, 1ikihby, bC. d.. 
 PULSE  WIDTHS  AND FILTER MATCHING LOSS FOR THE THREE WEIGHTING FUNCTION TYPES 4HE APPLICATION  OF n 
 8 * 
 Nessmith, J. T.: Range Instrumentation Radars, IEEE ELECTRO '76, Boston, Mass., May 11 -14,  1976.  63. 
 A's are theoretical values for ideal postdetection-integration  improvement as computed by Marcum4' for a false-alarm probability of (From J. Brit. IRE.49)  2.5 dB per doubling mentioned above. 
    (  
 #/5.4%2-%!352%3   Ó{°£Î 4HREE HYPOTHESES HAVE TO BE TESTED   THE NULL HYPOTHESIS  ( CORRESPONDING TO THE  PRESENCE OF NOISE IN THE TWO CHANNELS    THE  ( HYPOTHESIS PERTAINING TO THE TARGET  IN THE MAIN BEAM  AND   THE  ( HYPOTHESIS CORRESPONDING TO TARGET OR INTERFERENCE  SIGNAL IN THE SIDELOBE REGION 4HE NULL AND  ( HYPOTHESES CORRESPOND TO THE USUAL DECI 
 The stalo, coho. and the mixer in  which they arc combined plus any low-level amplification are called the receiver-exciter be­ cause of the dual role they serve in hoth the receiver and the transmitter.  The characteristic feature of coherent MTI radar is that the transmitted signal must be  coherent (in phase) with the reference signal in the receiver. 
 ENTRY VEHICLE 4HE OTHER MAJOR TYPE OF ACTIVE JAMMER IS DECEPTIVE %#- $%#-   $ECEPTION IS  THE INTENTIONAL AND DELIBERATE TRANSMISSION OR RETRANSMISSION OF AMPLITUDE  FREQUENCY  PHASE  OR OTHERWISE MODULATED INTERMITTENT OR #7 SIGNALS FOR THE PURPOSE OF MISLEAD 
 COMPRESS  WHICH KEEPS DOWN INTER 
 85. C. S. 
 The ring is split, with  the split diametrica11y opposite the output cavity. The ring is also cut to accommodate the  output coupling slot. Near the output, on both sides of the output coupling, the ring is firmly  attached to the cavity wall, but is unattached otherwise. 
 23.1–23.25. 101. Sensors 2019 ,19, 1649 5. 
 Ifthephase oftheVSWR ischanged, say byincreasing the line length between the magnetron and the mis- match until point Bisreached, the power output falls to425 kw. The efficiency ofthe magnetron atpoint Aisthus 50per cent greater, but operation atthis loading isunsatisfactory foranother reason. Asrepre- sentative ofageneral class ofload instability, consider achange inphase angle about the loading Aof*7“5° (dotted arrows) which might resuit from theturning ofanimperfect rotary joint. 
 ithasbeensaidthatthecancellation insomeregionsof"heavyrain" mightbeincreased byasmuchas12dBoverthatobtained withcircular polarization.8! However, thepolarization thatisoptimum foroneparticular regionmightactually proveto beworsethanthecancellation obtained withcircular polarization insomeotherregion.The optimum polarization thusdepends onthedistance traveled inrain,sothattheantenna polarization needstobecontinuously adjusted.79Thegreaterthepenetration intoarain­ storm,themoreelliptical willbecomethepolarization ofanoriginally circular polarized wave. Thustomaintain theimprovement inraincancellation withelliptical polarization, thepolar­ izationonreceiveshouldbemadevariable withrange(time).Withsuchadaptive polarization ithasbeensuggested thatanimprovement incancellation or6to9dBmightbeobtained consistently.82. 506 INTRODUCTION TO RADAR SYSTEMS  Still another factor which reduces the effectiveness of circular polarization in rain clutter  is the different reflection coefficients experienced.by the horizontal and vertical polarization  components on reflection from the surface of the land or the sea. 
 With  € ΩAnt=0,08sr(from 22dBi) the antenna noise temperature results in  € TAnt=8,2°K. Higher antenna noise temperature values TAnt result from higher antenna gains.  . 
 Itmust benoted that this result isindepend- ent ofthevalue ofinductance used. The network voltage obtainable with inductance charging inpractice liesbetween 1.8and 1.95 times thed-csupply voltage, because ofresist- ance losses inthecharging reactor. IfLOand Carethevalues ofcharging inductance and network capacity, t4resonanm” charging isobtained when the repetition rate, f,=l/(r V“LOC). 
 WAVELENGTH RADARS ARE  NECESSARY FOR THE STUDY OF SEVERE STORMS  SHORTER WAVELENGTH MILLIMETER 
 DRIVEN MOTION AS WELL AS hSPIKYv BEHAVIOR 4HESE FACTS OFTEN REQUIRE HIGH RESOLUTION AND MULTIPLE LOOKS IN FREQUENCY OR TIME TO ALLOW SMOOTHING OF SEA CLUTTER FOR STABLE DETECTION AND TRACK   )F THE TARGET IS A SIGNIFICANT SURFACE VES 
 HAND SIDE ANTENNA IS A LOW 
 COMPRESSION SIDELOBES WILL NOT EXCEED THE SYSTEM  NOISE AFTER THE -4) CANCELER  THE SYSTEM STABILITY BUDGET MUST ENSURE THAT THE INSTABILITY SIDELOBE LEVEL IS LOWER THAN THE DYNAMIC RANGE OF THE RECEIVING SYSTEM 4HE RECEIVING SYSTEM DYNAMIC RANGE IS ULTIMATELY DETERMINED IN A WELL 
 TECHNOLOGY v IN 0ROC OF THE %U-#  VOL ))  -ILAN  )TALY  3EPTEMBER   PP n  * 3ACHS AND 0 0EYERL  h#HIP INTEGRATED 57" RADAR ELECTRONICS v PRESENTED AT 4HIRD $4)&  7ORKSHOP   'ROUND 0ENETRATING 2ADAR IN 3UPPORT OF (UMANITARIAN $EMINING   *2#  )SPRA  )TALY   3EPTEMBER   * 2 7AIT  h0ROPAGATION OF ELECTROMAGNETIC PULSES IN A HOMOGENEOUS CONDUCTING EARTH v  !PPL  3CI 2ES "  VOL   PP n    2 7 0 +ING AND 4 4 .U  h4HE PROPAGATION OF A RADAR PULSE IN SEA WATER v  * !PPL 0HYS         PP n    $ " 2UTLEDGE AND - 3 -UHA  h)MAGING ANTENNA ARRAYS v  )%%% 4RANS  !0  1   PP n     &EDERAL #OMMUNICATIONS #OMMISSION  HTTPWWWFCCGOVABOUTUSHTML. ÓÓ°£ ÛÊ >ÀiÊ,>`>À `ÞÊ ÀÀÃ ÓÓ°£Ê  /," 1 /"  )N TERMS OF THE NUMBER OF SYSTEMS IN WORLDWIDE USE  CIVIL MARINE RADAR #-2  IS THE  LARGEST RADAR MARKET OF ALL TIME 4HE NUMBER OF VESSELS OF ALL TYPES CURRENTLY FITTED WITH RADAR PROBABLY AMOUNTS TO AROUND  MILLION  BUT THERE ARE NO OFFICIAL RECORDS TO VERIFY THIS ESTIMATE #-2 BREAKS DOWN INTO TWO MAIN APPLICATION AREAS 4HE VAST MAJORITY ARE USED AT  SEA AND ON NAVIGABLE WATERWAYS BY SHIPS AND SMALLER CRAFT THE OTHERS ARE USED BY PORT AND COASTAL AUTHORITIES FOR VESSEL SURVEILLANCE FROM LAND 
 J.: Improved Low-Elevation-Angle Tracking with Use of Frequency Agility, Naval Research  Laboratory Rept. 7378, Washington, D.C., Mar. 17, 1972. 
 Johnston, “The ECCM improvement factor (EIF): illustration examples, applications, and  considerations in its utilization in radar ECCM performance assessment,” Int. Conf. Radar ,  Nanjing (China), November 4–7, 1986, pp. 
 R. Billam, “Parameter optimisation in phased array radar,” in Radar 92 , Brighton, UK, 12–13  October 1992, pp. 34–37. 
 10.8. Load Requirements.—It isnot enough tosay that apulser shall produce apulse ofacertain duration and magnitude. The nature ofthe load imposed upon the pulser, the operational problem faced by the complete equipment, and certain other practical factors usually require consideration. 
 Receiver protectors. Sincethekeep-alive intheTRisnotusuallyenergized whentheradaris turnedoff,considerably morepowerisneededtobreakdowntheTRthanwhenitisenergized. Radiations fromnearbytransmitters milYtherefore damagethereceiverwithoutfiringtheTR. 
 Chen, H.M.; Li, M.; Lu, Y.L.; Zuo, L.; Zhang, P . Novel supper-resolution wide area imaging algorithm based on APES. Syst. 
 4(% 
 CONTROL TUBES /FTEN WITH SUCH RADARS  IT WOULD COST MORE TO REPLACE THEM WITH SOLID 
 Phillips. R. M.: High Power Ring-Loop Traveling-Wave Tubes for Advanced Radar, Microwal'e  Srsr ,.,,, N 1'1\·s, vol. 
 # BIASED TRANSISTORS ARE ACTUALLY hOFFv WITHOUT THE PRESENCE OF AN 2& SIGNAL ON THE INPUT &OR USE IN RADAR TRANSMITTER AMPLIFIERS  THE #LASS 
 Change of beamwidth with steering angle. The half-power beamwidth in the plane of scan  increases as the beam is scanned off the broadside direction. The beamwidth is approximately  inversely proportional to cos 00, where 80 is the angle measured from the normal to the  anterlna. 
 799 803,  November, 1974.  109. Brown, J. 
 The transistor amplifier can be applied over most of the entire range of frequencies of inter­ est to radar.10· 19·20 The silicon bipolar-transistor has been used at the lower radar frequencies  (he low L band) and the galium arsenide field-elTect transistor (GaAs FET) is preferred at the  60  5 0 - CD  ,:J 4 0 .  ~ ::,  O'  (I.) 30 .. "' 6 z  20  1 0 - 5000 10,000 30,000  Frequency -MHz  Figure 9.4 Noise figures of typical microwave receiver front-ends as a function of frequency-. 
 Digital I and Q generation does not produce signals without error,  as is often stated, but instead allows the generation of these signals with errors  that are sufficiently small to be considered negligible. The primary cause of the  imbalance is the non-ideal filter responses. An infinite number of taps would be  required to set the passband gain to unity and the stopband gain to zero; however,  for most applications, sufficient processing resources are available to reduce the  errors to insignificant levels. 
 We shall now consider the radar functions of target acquisition and tracking which provide the intelligence for guidance. Emphasis is on semiactive or active coher- ent operation unless noted otherwise. Reference-Channel Operation.2'5'6'32 Within the context of a coherent system, the seeker must have available as a reference a precise replica of the il- luminating signal. 
 Rlass. J.: Multidirectional Antenna-A New Approach to Stacked Beams, 1960 IRE ltir~~rtiariotiul  Cotiretlriot~ Recorrl, pi. I, pp. 
 Vegetation or trees will have a  back-and-forth motion due to the wind; hence, the doppler spectrum from such clutter will be  distributed on both sides of the transmitted frequency, especially if observed over a sufficieiit  period of tiye. By splitting the received spectrum into two halves about the transmitted carrier  and subtracting the lower part from the upper part, the symmetrical clutter spectrum will  cancel and the asymmetrical target spectrum will not. This method of suppressing the clutter  relative to the target has been called the Kalmus clutter jilter. 
 CAL PATTERN SHAPING 4HE LONG 
 One is the rounded wingtips, which tend to  reduce tip-spawned reflections of surface traveling waves that might build up along  the wing’s leading edges. Another is the use of thin absorber coatings that are serrated  around the edges of hatches, covers, and canopies to suppress reflections from edge  discontinuities. Yet another is the fact that the B-2, like the F-117, has a subsonic  airframe. 
 DIMENSIONAL EXPRESSION SEE (OLIDAY ET AL   "ECHMANN AND 3PIZZICHINO  &UNG AND 0AN  AND 6ALENZUELA  FOR EXAMPLE    SY Y       ;;   = 
 PULSE TRANSMITTER FREQUENCY CHANGE IF A PULSED OSCILLATOR  MUST BE LESS THAN   $F   PT(Z    WHICH IS A STABILITY OF ABOUT  PARTS IN 0ULSE 
 A stretch processor with  unequal frequency-slope waveforms requires pulse compression of the residual linear  FM at the output of the correlation mixer. A linear FM signal with a slope of a in − a R  occurs at the target range, which is offset in frequency from the IF carrier frequency  by a R(tR − t). With the range-doppler coupling of the LFM waveform, the apparent  time delay of this target will be  tapp = −aR (tR −t)/(a −aR) (8.31) This result can be interpreted as yielding a time-expansion factor of a R/(a  − a R)  for the compressed pulse. 
 J. J. Kovaly, Synthetic Aperture Radar , Norwood, MA: Artech House, 1976. 
 ,TEI ON SS MAX     rAVS P 7    4HE RADAR DESIGNER HAS LITTLE CONTROL OVER THE REVISIT TIME  TS OR THE ANGULAR COVERAGE  7  WHICH ARE DETERMINED MAINLY BY THE JOB THE RADAR HAS TO PERFORM 4HE RADAR CROSS  SECTION ALSO IS DETERMINED BY THE RADAR APPLICATION )F A LARGE RANGE IS REQUIRED OF  A SURVEILLANCE RADAR  THE RADAR MUST HAVE THE NECESSARY VALUE OF THE PRODUCT  0AV!E  &OR THIS REASON  A COMMON MEASURE OF THE CAPABILITY OF A SURVEILLANCE RADAR IS ITS POWER 
 The stable base compensates for roll and  pitch. Yaw can usually be taken into account by a correction to the angle read-out.  In some applications, the pitch is small so ,that little harm results from omitting the  stabilization of the pitch axis, leaving only the roll axis stabilized. 
 INTERROGATING THE TARGET (OWEVER  IN AN AIR TRAFFIC CONTROL SITUATION USING !4#2"3  TARGETS WOULD BE INTERROGATED AT EVERY SCAN AND  CONSEQUENTLY  EITHER DETECTIONS OR TRACKS COULD BE INTEGRATED 2ADARn$&  "EARING  3TROBE  )NTEGRATION  #ORRELATING RADAR TRACKS WITH $&  DIRECTION FINDING  BEARING STROBES ON EMITTERS HAS BEEN CONSIDERED BY #OLEMAN  AND  LATER BY 4RUNK AND 7ILSON  4RUNK AND 7ILSON CONSIDERED THE PROBLEM OF ASSOCI 
 Tracking on the direct signal avoids  the angle errors introduced by the multipath. The range-resol~~tion required to separatc thc  direct from the ground-reflected signal is  where ha = radar antenna height, h, = target height, and R = range to the target. For a radar  height of 30 m, a target height of 100 m and a range of 10 km, the range-resolution must be  0.6 m, corresponding to a pulse width of 4 ns. 
 spurious quanrizatiorl lobes, similar to grating lobes. The peak-quantization lobe relative to the  main beam, when the phase error has a triangular repetitive distribution is  I Peak quantization lobe = 22B  This applies when the main beam points close to broadside and there are many radiating  elements within the quantized phase period. The position of the quantization lobe in this case  is  sin 0, = (I -- 2B) (lo (U.33)  where O0 = angle to which main beam is steered. 
 3 17  (ID ratio. antenna. 239  Feeds :  array antenna. 
 ALARM PROBABILITY  CAN BE OPTIMIZED TO PROVIDE THE LOWEST REQUIRED SIGNAL 
 Strobe control unit type 454. Altitude control, range lamps and stick length control were associated with the blind bombing attack system; (a) [ 6], (b) [ 1].Airborne Maritime Surveillance Radar, Volume 1 4-12. automatic gain control (AGC) was introduced. 
 MENT OF OCEAN SURFACE CONDITIONS v 0ROC )%%%  VOL   PP n  *UNE    $ " 4RIZNA AND * - (EADRICK  h)ONOSPHERIC EFFECTS ON (& OVER 
 I_6 Filter-bank design, 2.52 to 2.59 Filter mismatch loss, in MTI, 2.22 to 2.23 Filters, in radar, 6.24 to 6.29 Finite impulse response (FIR) filters, 2.33, 25.26 to 25.28 FM-CW radar, 1.5, 9.20 Focused SAR, 17.2 Foliage-penetration (FOPEN) SAR, 17.33 to 17.34 Fog, attenuation in, 19.12 Forward scatter, in bistatic radar, 23.21 Fourier transform, 8.38 Frank codes, 8.19 to 8.20 Free-space propagation, 26.13 to 26.15 Frequency agility, 1.9, 24.31 Frequency diversity, 1.9, 24.31 Frequency, effect on radar, 1. 14 to 1.18 Frequency multipliers, 6.49 to 6.50 Frequency synthesis, 6.21 to 6.22 Front end, of receiver, 6.10 to 6.14 G GaAs PHEMT FET, 11. 12 to 11.16 Geometrical optics, 14.20 to 14.21 and ground echo, 16. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar.  PULSE COMPRESSION RADAR  8.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 high sampling rates and filtering the output. 
 1, p. 410).  Fven with an index of refraction in the vicinity of 0.5 to 0.6, the thickness of the metal­ plate lens becomes large unless inconveniently long focal lengths are used. 
 Doc. 116, 1981. 34. 
 Purves. and P. Watkins: Propagation Throi~gli an  I!lcvated Duct: Tradewinds 11 I, IEEE Trurts., vol. 
 In1903aGerman engineer bythenameofHiilsmeyer experimented withthedetection of radiowavesreflected fromships.Heobtained apatentin1904inseveralcountries foran obstacle detector andshipnavigational device.2Hismethods weredemonstrated beforethe German Navy,butgenerated littleinterest. Thestateoftechnology atthattimewasnot sufficiently adequate toobtainrangesofmorethanaboutamile,andhisdetection technique wasdismissed onthegrounds thatitwaslittlebetterthanavisualobserver. Marconi recognized thepotentialities ofshortwavesforradiodetection andstrongly urgedtheirusein1922forthisapplication. 
 Time  sidelobes increase  while mainlobe  response decreases  for higher doppler  (characteristic  of a thumbtack- like ambiguity  function). Used,  therefore, for  low-speed target  applications and  with small TB  products.Highest sensitivity  to doppler shift.  Time sidelobes  increase while  mainlobe response  decreases for  higher doppler  (characteristic of  a thumbtack-like  ambiguity function). 
 MATION OF THE DIFFERENTIAL QUANTITIES BETWEEN ECHOES FROM THE TWO POLARIZATIONS /NE  CAN DERIVE IMPROVED RAINFALL RATES AS WELL AS OTHER PHYSICAL INFORMATION ON THE TYPE OF PRECIPITATION  AS FUNCTIONS OF POLARIMETRIC MEASUREMENTS THAT RELATE THE DIFFERENCES IN THE HORIZONTALLY AND VERTICALLY POLARIZED SIGNALS "Y FAR THE MOST COMMON POLARIMET 
 Experiments and Analysis In order to verify the effectiveness of the algorithm in this paper, point target simulation data, electromagnetic software simulation data, and measured data in anechoic chamber is adopted to carry out imaging veriﬁcation and performance analysis, respectively. 4.1. Numerical Simulations The simulation target is composed of 46 scattering centers withe shape of plane model, and its distribution is shown in Figure 3. 
 Operation of the attenuator is illustrated in ﬁgure 4.5[8]. This consisted primarily of a T junction, one of which lead to the scanner and the other to the transmitter dummy load. Inserted in these two branch arms were two closed sections ofwaveguide containing resonant loops which were linked together and which enabled the output of the transmitter to be divided in any desired proportion between the scanner and the dummy load. 
 MUM -4) FILTER ARE FOUND AS THE EIGENVECTOR CORRESPONDING TO THE SMALLEST EIGENVALUE OF THE CLUTTER COVARIANCE MATRIX AND THE -4) IMPROVEMENT FACTOR IS EQUAL TO THE INVERSE OF THE SMALLEST EIGENVALUE 4HE OPTIMUM IMPROVEMENT FACTOR FOR THE THREE MODELS FOR THE SPECTRUM OF LAND CLUTTER INTRODUCED IN 3ECTION  HAVE BEEN COMPUTED BASED ON THIS ABOVE APPROACH &OR THE GAUSSIAN CLUTTER SPECTRUM  THE OPTIMUM IMPROVEMENT FACTOR IS SHOWN IN  &IGURE  AS A FUNCTION OF THE RMS RELATIVE SPECTRUM WIDTH  A SSUMING ZERO MEAN FOR  THE SPECTRUM #ALCULATIONS ARE SHOWN FOR -4) CANCELERS OF ORDER .    THROUGH  &OR THE POLYNOMIAL CLUTTER SPECTRUM  THE OPTIMUM IMPROVEMENT FACTOR IS SHOWN IN  &IGURE   AGAIN AS A FUNCTION OF THE 2-3 RELATIVE SPECTRUM WIDTH ASSUMING ZERO MEAN FOR THE SPECTRUM &INALLY  FOR THE EXPONENTIAL CLUTTER SPECTRUM MODEL  THE OPTIMUM IMPROVEMENT FAC 
 10.18 the loss in signal-to-noise ratio is plotted as a function of doppler shift. To obtain the total SNR loss with respect to that achieved with matched-filter reception, it is necessary to add 1.15 dB (see Fig. 10.16c for Taylor weighting) to the loss of Fig. 
 original sense breaks clown insuch cases, because itisthen nolonger possible todefine asingle quantity characterizing thetarget —namely the cross section—in such amanner that the received power depends only ontheproperties oftheradar set(P,G,and .4),ontherange, and onthe cross section. .%slong asthetarget does notextend inelevation o~.er more than one lobe (anassumption that isusually correct forairplanes) amodification. 80 PROPERTIES OFRADAR TARGETS [SEC. 
 Using more pulses makes possible narrower rejection notches  and thus less bias for estimates of precipitation with zero radial velocity . FIGURE  2.52 Response of ASR-11 FIR filters low-PRF ( fr = 855 pps) filters operating against fixed clutter  with HBW = 17. The unambiguous doppler interval (  f T = 1) is 45.8 m/s for the parameters used to calculate  this response. 
 E.: Pulse Compression: Key to More Efficient Radar Transmission, Proc. IRE, vol. 48, pp. 
 Inmost radar systems, :Rz however, afewmicrowatt, directlyt6k ~ from the magnetron, would swamp FromLoad driver;L,; any but the strongest echoes which circuit ++*5mhj might happen toreturn coinciden- 1L2 12mh tally with the appearance ofVA. LA Asamatter ofpractical experience,SFl 1‘~ 4 * Vm* should bekept below 10perE, EP=+13 kv 1200v cent ofV-O ifall possibility of ~IG. 1031.-Schematic diagram ofoutput. 
 PRISES  TRANSMITRECEIVE MODULES )N OTHER REGARDS  ITS MODES REFLECT THE BASIC 2!$!23!4 
 6.5HYBRID LINEAR-BEAM AMPLIFIER Bycombining theadvantages orthe'klystron andthetraveling-wave tubeintoasingledeviceit ispossible toobtainahigh-'power amplifier withabandwidth, efficiency, andgainflatness betterthancanbeobtained witheithertheusualklystron orTWT.7Onesuchdeviceisthe VarianTwystron (atrade nam~),whichisahybridconsisting ofamulticavity klystron input sectioncoupledtoanextend~d interaction traveling-wave outputsection.Thelimitation tothe bandwidth ofaklystron isgenerally theoutputcavity.Itcannotbemadebroadband withoula decrease inefficiency. Theslow-wave circuitsoftraveling-wave tubeshaveabroader band­ widththanklystron resonant cavitIes; andwhenusedfortheoutputofaklystron, asinthe Twystron, abroadbandwidth canbeachieved withthepeakandaveragepowercapabilities of aklystron. TheC-bandVarianVA-146Twystron familyoftubesprovides peakpoweroutputsfrom 200kWto9MWwithbandwidths greaterthan10percent.TheVA-146N produces a2.5MW peakpowerwitha20pspulseata0:004dutycycleoveraitdBbandwidth of500MHzatC band.Thegainis31dBandtheefficiency atmidband is40percent. 
 Ingeneral, periodic waveforms maybedesigned tosatisfytherequire­ mentsofaccuracy andresolution provided theresulting ambiguities canbetolerated. A waveform consisting ofasinglepulseofsinusoid avoidstheambiguity problem, butthetime delayandfrequency cannotsimultaneously bemeasured toasgreatanaccuracy asmight ~e desired. However, itispossible todetermine simultaneously boththefrequency andthetime delaytoanydegreeofaccuracy withatransmitted waveform containing alargebandwidth pulse-width product (largepcx.product). 
 The price is higher system complexity and cost. Thus, "oscillator versus amplifier" is one of the basic choices that must be made early in radar system design. Some of the factors entering into this choice are given below. 
 CATE THAT THE SLOW 
 LEVEL DISTRIBUTIONS FOR THE EXAMPLE  SHOWN IN &IGURE  4HESE APPROXIMATELY LOG 
 Rogers. D. V., and R. 
 33 of" Radar Handbook," M. I. Skolnik (ed.): McGraw- Hill Book Co., New York, 1970. 
 The range and/or doppler ambiguities are resolved in search and, if necessary, in the  Transition-to-Track phase. By using the unambiguous range and velocity predictions  ch04.indd   38 12/20/07   4:53:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Repr.3119,May17.1965. RI.Kaufman. I.:TheBandBetween Microwave andInfrared Regions, Proc.IRE, vol.47.pp.381-396. 
  
 F TO  
 35. E. Carlson, “Low probability of intercept techniques and implementations,” in  IEEE National  Radar Conference , 1985, p. 
     F F. DF ¯§ ©¨ ¨¨¨ ¨ ¨¶ ¸· ··· · ·    4HE  SPECIFIC FREQUENCIES COULD LOGICALLY BE CHOSEN AS THE CROSSOVER BETWEEN INDI 
 There is a thermal time constant associated with the numerous thermally resistive layers between the transistor junction and the heat sink or cold plate to which the device is attached. This occurs because each layer (silicon, ce- ramic, transistor flange) not only has a thermal resistance but also exhibits a thermal capacity. Since the overall thermal time constant for a typical L-band power transistor may be on the order of hundreds of microseconds, the tradeoff between peak and average power versus device size can be significant for typical radar pulse widths in the 20- to 1000-jjis range. 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°x£ 4HE LOWER THRESHOLD  4, DETERMINES THE PROBABILITY THAT THE CORRECT RADAR TRACK IE    THE ONE ASSOCIATED WITH THE $& SIGNAL  WILL BE INCORRECTLY REJECTED FROM FURTHER CONSID 
 J“ery briefly, theprinciple isthis: ifasphere isstruck byacircularl,v polarized plane wave, formed bypassing alinearly polarized plane wave through aquarter-~vave plate, zthescattered wave observed intheback- ‘There areotherminordifferences: thelengthinrange ofa“noise spot” isdeter- rniaed bythereceiver bandwidth andthecathode-ray-tube spot size. Theleugth in range ofa“rain spot” depends onthepulse length aswell. Thewidth, inazimuth, ofanoise spot depends onl’y oncathode-ray-tube spot size, orsweep interval, which- ever islarger, whereas theazimuthal width ofarain spot depends ontheantenna beamwidth. 
 However, as you travel  from the coastal environment into the open ocean, this trapping layer may well rise  from the surface, thereby creating the surface-based duct. Surface-based ducts tend  FIGURE 26.4  Surface ductTrapping layer Surface duct Modified refractivityHeight ch26.indd   10 12/15/07   4:53:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Smith, “Calibration of synthetic aperture radar, Dig.  IGARSS  ’81, pp. 938–943, 1981. 
 To allow thecentimetric ASV radars to access these, the Lucero transponder system was developed, as described in chapter 6. Chapter 7provides an overview of the comparative performance of the various ASV systems and also considers how theperformance actually achieved can be compared with performance predictions based on modern analysis methods. Finally, chapter 7concludes with an overview of the ASV systems in service at the end of WWII, including a brief discussion of theAmerican radar systems in service with Coastal Command and some of the ASV radars developed for the FAA. 
 PHASE  1  SIGNALS  ARE DIGITIZED USING A PAIR OF !$ CONVERTERS PROVIDING A REPRESENTATION OF THE )& SIGNAL  INCLUDING PHASE AND AMPLITUDE WITHOUT LOSS OF INFORMATION 4HE RESULTING DIGITAL DATA CAN THEN BE PROCESSED USING A WIDE VARIETY OF DIGITAL SIGNAL 
 T. Wu: "The Scattering and Diffraction of Waves," Harvard University Press, Cambridge, Mass., 1959. 95. 
 Radar Conf., pp. 222-231, Paris, 1978. 19. 
 Hougardy, R. W., and R. C. 
 Originally, MTI radar used acoustic delay lines in which electromagnetic signals were con-  verted into acoustic waves; the acoustic signals were delayed, and then converted back into  electromagnetic signals. The process was lossy (50 to 70 dB might be typical), of limited  dynamic range, and spurious responses were generated that could be confused for legitimate  echoes. Since acoustic waves travel with a speed about lo-' that of electromagnetic waves, an  acoustic line can be of practical size whereas an electromagnetic delay is not. 
 If amplitude weighting of the synthetic aperture is desired to reduce the sidelobes, a  shaded transparency with uniform phase thickness can be inserted adjacent to tlle data film in  plane P,.  Digital processing. The recirculating delay-line integrator, range-gated filter bank, and 1. 
 The work in [ 3] concerns the processing of multi-pass squinted SAR data. The proposed algorithm combines images acquired with the same azimuth squint angle on each pass for performing 3D imaging (as in SAR tomography), and data acquired with di ﬀerent azimuth squint angles for reﬁning the suppression of azimuth sidelobes. A performance analysis is carried out by using both simulated point targets and real data acquired by TerraSAR-x satellite mission. 
 China,” in Proceedings of EUSAR , Dresden,  Germany, ITG VDE, 2006. ch18.indd   64 12/19/07   5:15:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 of the 1997 Symposium on Wireless  Personal Communication , Blacksburg, V A, June 1997.FIGURE 25.44  Direct-sampling radar digital receiverRF IN SAMPLE CLOCKNANALOG DIGIT AL BPFTO BA CKEND PROCESSINGDDCI QDIGIT AL PC QI ADC ch25.indd   38 12/20/07   1:40:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 
 9.14, and aperspective drawing ofthe antenna isshown asFig. 9.25. The radar beam produced was about 0.55” wide inazimuth; this narrow beam, coupled with the }~psec pulse length used, gave the sethigh resolution both inrange and inazimuth. 
 For Earth explor ation a small degradation of the range res o- lution results from the angled or diagonal view as repr esented in Figure 9.1.  . Radar System Engineering  Chapter 9 – Synthetic Aperture Radar  76        Figure 10.1  Range resolution of a Radar with a diagonal incident wave trajectory. 
 RATE TRACKING THE BETA LOOP   AND MEAN SIGNAL POWER THE !'# LOOP   #! '       #!  "#  !! % ! 
 C.L.B. 1  . PREFACE  INCE THE EVOLUTION CONTROVERSY AT THE CLOSE OF  the nineteenth century the scientific method of  objective observation, experiment, and cool statistical  examination has invaded every department of know-  ledge, almost, it would seem, to the total exclusion of  genius. 
 Against surfaced U-boats performance was considered good and ASV could be used to search large areas. However, even in good conditions search performance against schnorkels was low. The problem was that of discriminating the small radar return from the schnorkel with the returns from the surrounding sea. 
 V.: Fmthcr Rl•sults on the Detection of Targets in Non-(iaussian Sea Clutter, IEEE  Tra11s .• vol. AES-7. pp. 
 16.17. Inthecase ofamoving target thebeat cycles shift horizontally from pulse topulse and give afilled-in appearance onthe A-scope. Figure 16.17b really represents coherent i-frather than coherent video signals, with the coherent oscillator acting asasecond local oscillator. 
 Thus, the possibility of azimuth ambiguities arises as a natural consequence of the signals radiated and of the processing method. Ordinarily, these potential am- biguities in azimuth are suppressed by the illumination factor. The illumination pattern £ is chosen so that the values of p corresponding to more than one value of m are not illuminated. 
 Assume a CW radar with an antenna beam width of 08 deg scanning at the rate of Os deg/s.  The time on target (duration of the received signal) is f> = 08/0s s. Thus the signal is of finite  duration and the bandwidth of the receiver must be of the order of the reciprocal of the time on  target iJs/08. 
 Transmission takesplaceonlyon thelowerofthetwobeams.Atshortrange,reception isontheLIpperheamonly.Thisheamis tiltedtominimize illumination oftheground. Asthetransmilled pulsetravelsheyondthe groundclutterrange(typically 50milesorgreater)thereceiver isswitched tothelowerbeam forlong-range reception. IntheARSR-3 theratioofthelower-heam gaininthedirection of thehorizontothatoftheupper-beam gaininthesamedirection is16dB..~b(Thelowerbeam hasitshalf-power pointonthehorizon.) Theantenna elevation patternisshapedtohaveat thehigheranglesagreatergainthanwouldbenormalwithacosecant-squared pallern.This permitssensitivity timecontrol(STC)tobeusedwiththeradarwithoutalossofcoverage at highaltitudes andshortrange(Fig.7.27).TheSTCisemployed toreducenear-incluller, especially frombirdsandinsects.InthisradartheSTCisappliedintheRFaheadofthe low-noise amplifier. 
 This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). 211. sensors Article Monitoring Land Subsidence in Wuhan City (China) using the SBAS-InSAR Method with Radarsat-2Imagery Data Yang Zhang1, Yaolin Liu1,2,3, Manqi Jin1, Ying Jing1,Y iL i u1, Yanfang Liu1,*, Wei Sun4, Junqing Wei1and Yiyun Chen1,* 1School of Resource and Environmental Sciences, Wuhan University, Wuhan 430079, China; zhangy1010@whu.edu.cn (Y.Z.); liuyaolin2010@163.com (Y.L.); kingerin@163.com (M.J.); y.crystal@whu.edu.cn (Y.J.); liuyi2010@whu.edu.cn (Y.L.); weijunqing@whu.edu.cn (J.W.) 2Key Laboratory of Geographic Information System, Ministry of Education, Wuhan University, Wuhan 430079, China 3Collaborative Innovation Center for Geospatial Information Technology, Wuhan 430079, China 4Wuhan Geomatics Institute, Wuhan 430022, China; gnss.wei@gmail.com *Correspondence: yﬂiu59@126.com (Y.L.); chenyy@whu.edu.cn (Y.C.) Received: 21 December 2018; Accepted: 5 February 2019; Published: 12 February 2019/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: Wuhan city is the biggest city in central China and has suffered subsidence problems in recent years because of its rapid urban construction. 
 J.: Faster. Lighter 3-11 Radars in Sight for Tactical Warfare. Electronics, vol. 
 The goal is similar to that pursued with the empirical filter  designs discussed earlier but filters with a large number of taps can be designed to  exacting specifications. As an example, consider the design of a doppler filter bank for an S band (3.0 GHz)  radar using a CPI of N = 25 pulses using a PRF of 6 kHz. Assume that the radar require - ments call for a suppression of stationary land clutter by 80 dB and a suppression of  moving clutter (rain) by 50 dB. 
 One of the most significant design  features of the radar is to provide automatic detection, tracking, and illumination of  low-altitude threat missiles in the adverse environmental conditions routinely found  in coastal waters. SPY-3 uses three fixed-face arrays, each containing around 5,000 transmit/   receive (T/R) elements (see Figure 13.51). These elements are connected to   T/R integrated multi-channel modules, each of which drives eight elements. 
 OPTICS INTEGRAL IS EASY TO EVALUATE FOR FLAT METALLIC PLATES BECAUSE THE  PHASE IS THE ONLY QUANTITY WITHIN THE INTEGRAL THAT VARIES  AND IT VARIES LINEARLY ACROSS THE SURFACE 7HEN APPLIED TO A RECTANGULAR METAL PLATE  THE INTEGRAL EVALUATION LEADS TO THE 2#3   RP KPE PE P!K KKW COS SIN SIN CO S SIN COSSIN ;;@ @ SSIN SIN SIN SINPE PE KW     WHERE !   @W IS THE PHYSICAL AREA OF THE PLATE   P IS THE ANGLE BETWEEN THE SURFACE  NORMAL OF THE PLATE AND THE DIRECTION TO THE RADAR   E IS THE ANGLE BETWEEN THE PLANE  CONTAINING THE LINE OF SIGHT AND THE EDGE WHOSE LENGTH IS  @  AND W IS THE WIDTH OF THE  PLATE ! MORE GENERAL PHYSICAL OPTICS FORMULA IS AVAILABLE FOR THE BISTATIC SCATTERING  FROM ANY POLYGONAL PLATE   )F WE SET  E   n OR n  WE OBTAIN A  PRINCIPAL PLANE 2#3 PATTERN INCIDENCE IN A  PLANE PERPENDICULAR TO A PAIR OF EDGES  7HEN E   n  %Q  BECOMES   RP KP P  P!K KCOS SIN SIN SIN;@ @     )F  WE SET E   n INSTEAD OF  E   n  WE GET NEARLY THE SAME ANSWER  EXCEPT THAT  K@  IN %Q  BECOMES  KW 4HE PHYSICAL OPTICS INTEGRAL IS NOT DEPENDENT ON THE POLAR 
 THIRD OF THE ANODE PEAK CURRENT 3INCE THE CONTROL ELECTRODE IS INSULATED AND SINCE SOME ENERGY IS DISSIPATED ON THE CONTROL ELECTRODE  IT CAN BE DIFFICULT TO COOL 4HIS CAN LIMIT THE MAXIMUM PULSE REPETI 
 The most apparent advantages that the solid-state system has over the former tube version are: 1. Much lower dissipation is experienced in the corporate feed because the modules are colocated with the antenna. As a result, the overall site efficiency has been nearly doubled, thus contributing to lower life-cycle costs. 
 availability  (fraction of time the radar works properly). and maintainability (sometimes these last three are  called RAM): electromagnetic compatibility (EMC) requirements; restrictions on size. weight,  cost, and delivery: type of prime-power available; restrictions on warm-up time and shut­ down procedures: and the form in which the output information from the radar is desired. 
 M. Bracalente, L. W. 
 Serafin, “New nowcasting opportunities using modern meteorological radar,” in Proc.  Mesoscale Analysis Forecast. Symp ., European Space Agency, Paris, 1987, pp. 
 Inthe next few sections itwill be assumed that asingle transmitter istorelay one setofdata ofeach 1Rangemarkers need betransmitted only ifsome error isunavoidably present in thetiming ofthemodulator trigger pulse. Angle markers, ontheother hand, furnish aconvenient check onthe accuracy with which the scanner motion isfollowed.. SEC. 
 CALLED SIDELOBE BLANKING 3,"  AND SIDELOBE CANCELER 3,#  !N EXAMPLE OF THE PRACTICAL EFFECTIVENESS OF THE 3," AND 3,# DEVICES IS PRESENTED IN THE LITERATURE  WHERE THE PLAN POSITION INDICATOR 00)  DISPLAY IS SHOWN FOR A RADAR  SUBJECT TO AN %#-  EQUIPPED WITH AND WITHOUT THE 3," AND 3,# SYSTEMS  /THER DISCRIMINATION MEANS ARE BASED ON POLARIZATION 4HE POLARIZATION CHARACTER 
 In practice, postdetection integration isusuallyemployed andtherewillbeafiniteintegration loss.Insuchacasethescanning-beam systemwillhaveanadvantage overthemultiple-beam system. (' In amultiple-beam systemwhichusesabroadtransmitting beamtoilluminate theregion covered bythecontiguous receiving beams,thebenefitofthetwo-way sidelobelevelsthatis characteristic ofaconventional scanning radarantenna isnotobtained. Thusitisusually desirable tosuppress thesidelobes ofthemultiple receiving beamsmorethanusualinorderto reducethelikelihood ofechoesfromlargetargetsbeingreceived viatheone-way sidelobes. 
 45. Ridenour, L. N.: " Radar System Engineering," MIT Radiation Laboratory Series, McGraw-f-f ill  Book Company, New York, 1947, sec. 
 PUTATIONS THAN THE FORMER  WE FOCUS HERE ON EDGE DIFFRACTION 4HE THEORY ASSUMES THAT A RAY STRIKING AN EDGE EXCITES A CONE OF DIFFRACTED RAYS  AS IN &IGURE  4HE HALF ANGLE OF THIS  DIFFRACTION CONE IS EQUAL TO THE ANGLE BETWEEN THE INCIDENT RAY AND THE  EDGE 5NLESS THE POINT OF OBSERVATION LIES ON THE DIFFRACTION CONE  NO VALUE IS ASSIGNED THE DIFFRACTED FIELD 4HE SCATTERING DIRECTION IN BACKSCATTERIN G PROBLEMS IS THE REVERSE  OF THE DIRECTION OF INCIDENCE  WHENCE THE DIFFRACTION CONE BECOMES A DISK  AND THE SCAT 
 Therefore, if the multiplier of Fig. 11.2 is  preceded by a matched filter, the form of the optimum gating signal will be  This is the Fourier transform of the doublet impulse 1r2(t), or first derivative of the inlpulst.  function df(t). 
 The distance L between the transmitter and the receiver is called the base- line range  or simply the baseline ; RT is the range between transmitter and target; and RR  is the range between receiver and target. The angles qT and qR are, respectively, the trans - mitter and receiver look angles , which are taken as positive when measured clockwise  from north. They are also called direction-of-arrival (DOA), angle-of-arrival (AOA), or  line-of-sight (LOS). 
 ( from J.P . Hansen and V. F . 
 DIMENSIONAL REFLECTIVITY CROSS SECTION OF THE SURVEYED  VOLUME 0ENETRATION DEPTH IN GENERAL INCREASES WITH WAVELENGTH AND ALSO WITH RADIATED POWER /N THE OTHER HAND  REFLECTIVITY DEPENDS ON THE DIELECTRIC CONTRASTS BETWEEN INTERNAL LAYERS A MATERIALS DIELECTRIC CONSTANT IS ALSO A FUNCTION OF WAVELENGTH )T FOLLOWS THAT SPACE 
 Alert: In fact, this is seldom if ever  true. Backscattered power is  proportional to |magnitude|2, not magnitude. Hence, the user must assure that the data  are indeed magnitude-squared before applying tools, such as speckle filters, that are  designed for s  0 dimensionality. 
 The total  tracking error can be defined as the error that is exceeded only 1% of the time due to  the sum of random errors and bias. The total range-tracking error is best in the region  0.6 < a < 0.9 with a minimum around 0.75. If accuracy for maneuvers is the dominant  concern, then one would probably tune this filter to 0.75 to achieve the lowest total  error for a 1-g acceleration. 
 46. Ulaby. F. 
 INCIDENCE SIGNALS ARE USUALLY FAIRLY STRONG 4HUS THE ANTENNA PATTERN MUST BE ACCURATELY KNOWN AND TAKEN INTO ACCOUNT IN THE DATA ANALYSIS ! PATTERN WITH STRONG MINOR LOBES MAY BE SIMPLY INADMISSIBLE 4HE SCATTERING COEFFICIENT IS DETERMINED BY APPLYING   00' D! 2RTT ¯L PS   )LLUMINATED AREA  4HE INTEGRATION IS OVER WHATEVER AREA IS ILLUMINATED SIGNIFICANTLY  INCLUDING THE REGIONS HIT BY THE MINOR LOBES 4HE USUAL ASSUMPTION IS THAT  R   IS CONSTANT OVER THE ILLUMINATED  AREA  SO THAT   00' D! 2RTT ¯LS P   )LLUMINATED AREA    4HIS ASSUMPTION WOULD BE TRUE ONLY IF THE ANTENNA CONFINED THE RADIATED ENERGY TO  A VERY SMALL SPREAD OF ANGLES AND TO A FAIRLY HOMOGENEOUS REGION 4HE RESULTING EXPRESSION IS  SP L    ¯  0 0' 2 D !R TT)LLUMINATED AREA   &)'52%     4YPICAL RECEIVER INPUT 
 (7.15) and (7.18), G(90)#^% (7.19)"B 95 where G^ and 4>5 are the beam widths in degrees in the two principal planes with the beam scanned to G0. If the aperture is made up of N equal radiating elements and is matched to accept the incident power, then the contribution to the overall gain is the same from all elements, whence G(G) - NG,(G)Ti (7.20) where Ge is the gain per element. It follows from Eq. 
 TORS 3EMICONDUCTORS THAT EXHIBIT LARGE BANDGAP VALUES ARE ESPECIALLY CAPABLE OF PRO 
 Pugh, S., and D. E. Walker: Reflector Surfaces for Communications and Radar Aerials," Design and  Construction of Large Steerable Aerials," / 11stit11tion of Electrical Engineers (London) I EE C 01!ference  P11hlicatim1 no. 
 Fromprofilesofindexofrefraction. classical raytracing2Bcan beappliedtodetermine howtherayspropagate. Generally, itisreasonable toassumethatthe properties oftheatmosphere varyonlywith height. 
 BEAM JAMMING THIS CONSEQUENCE SHOULD BE CAREFULLY CONSIDERED IN SPECIFYING THE ANTENNA RADIATION PATTERN 5SUALLY  SPECIFICATION OF THE SIDELOBES AS A SINGLE NUMBER EG   
 KNOWN SUPPLIERS OF SHIPBORNE RADAR GETTING INVOLVED IN THIS AREA 4HEY COULD OFFER ATTRACTIVE PRICES AS THE SUBSYSTEMS WERE DERIVATIVES OF THE RELATIVELY HIGH VOLUME SHIPBORNE MARKET /VER TIME  MUCH OF THE MARKET HAS BECOME MORE SOPHISTICATED  AND BECAUSE OF THIS  SPECIALIST ORGANIZATIONS NOW DOMINATE THE SUPPLY OF SYSTEMS FOR THIS APPLICATION 4HE LARGE COSTS ASSOCIATED WITH A MAJOR VESSEL TRACKING SERVICES 643  OPERATION  INCLUDING MASSIVE ANTENNA SUPPORT TOWERS  OPERATIONS BUILDINGS  SPECIAL 
 Yu, H.; Liu, Y.; Li, L.; Yang, W.; Liao, M. Stable feature point extraction for accurate multi-temporal SAR image registration. In Proceedings of the 2017 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Fort Worth, TX, USA, 23–28 July 2017; pp. 
 17.20. The mixing and switching ofthe signals forthefirst transmitter isfairly simple. Range markers and the proper setofangle markers aremixed with each setofvideo signals, and thetwo sets arefedtoavideo switch, which passes the MTI signals for the first 50miles orsoand the lower-beam signals thereafter. 
 The basic notion behind MFAR high power- aperture jamming is suggested in Figure 5.24.9,11,71,84 A threat emitter, whether surface or airborne, is first detected and recognized  by the spherical coverage radar warning receiver (RWR) function (possibly just an  application overlay on the RF and processing infrastructure shown in Figure 5.4).  If the intercept is inside the radar field of view (FOV), fine angle-of-arrival (AOA)  and possibly burst ranging are performed with the primary radar aperture, as shown  in the top portion of Figure 5.24. High-gain electronic support measures (ESM) are  then performed and recorded on the emitter main beam or sidelobes using the nose  aperture. 
 #7 "ANDWIDTH K(Z  n 7AVEFORM REPETITION FREQUENCY (Z  n 4X ANTENNA DESIGN 3INGLE VERTICAL LOG 
 The point target Mi(Xi,Rb)is focused at (Xi−Rstanθ,Rb−RS)in the time domain. The algorithm processing ﬂow is shown in Figure 6: (FKRGDWD '))7 3XOVHFRPSUHVVLRQ  rrHf5DQJH,))7   COMP r xHk k &RQVLVWHQWFRPSUHVVLRQ ,PSURYHG LQWHUSRODWLRQ  AZIMUTH b xHR k $]LPXWKFRPSHQVDWLRQ $]LPXWK,))7 )RFXVHG,PDJH Figure 6. Multi-angle SAR algorithm ﬂow chart. 
 ! WHICH FLEW ON THE FIRST  3HUTTLE THAT CARRIED A SCIENCE PAYLOAD   3)2 
 However, other forms of plotting- pattern data are also used, as illustrated in Fig. 6.2. This shows four forms of plotting the same sin x/x pattern, including (a) a polar plot of relative voltage (in- tensity), (b) a rectangular plot of voltage, (c) a rectangular plot of relative power (density), and (d) a rectangular plot of logarithmic power (in decibels). 
 The oscillation Bispassed through aphase shifter geared tothescanner, and theresulting wave Cproduces a pulse train D. Inorder toavoid early transients which might lead toconfusion with themaster pulse (especially after coding) the first two orthree pulses in thetrain areexcluded byswitch a.This switch iscontrolled byasquare wave from flip-flop b;itisarranged toturn onlate enough toexclude the required number ofpulses and toremain onuntil after theend ofthepulse. 700 RADAR RELAY [SEC. 
 56. Tomiyasu, K., Bistatic Synthetic Aperture Radar Using Two Satellites, IEEE EASCONRec., pp. 106-110, Arlington, Va., 1978. 
 D. L.. H. 
 NewYork,1968. 31.Nairn,N.P.:BrightRadarDisplays Employing Direct-View StorageTubes,Conference onAirTraffic ControlSrstems Engineering andDesign,London, Mar.13-17,1967,lEEConference Publication no. 2R,pp.7-10. 
 DATE INFORMATION CONCERNING THE MARK AND ITS INTEGRITY CAN BE  AUTOMATICALLY OR MANUALLY FED 
 In the optics region several approximations are available for making estimates or pre- dictions (see Sec. 11.3). CIRCUMFERENCE / WAVELENGTH = ZTTQ/\ FIG. 
 POSE IS TO BLANK SIDELOBE DETECTIONS  AS DESCRIBED IN 3ECTION  0OSTPROCESSING  &OLLOWING THE #&!2 IS DETECTION EDITING  WHICH CONTAINS THE SIDE 
 Biphase coding can be achieved in a simpler manner, as shown in Sec. 10.6. The phase control element supplies digital samples of the in-phase component / and the quadrature component Q1 which are converted to their an- alog equivalents. 
 Most birds fly at altitudes below about 2500 m, with peak numbers between 300 and l 200 m,  or even lower.95•96  Table 13.3 gives some examples of the radar cross sections of birds taken at three frequen­ cies with vertical polarization.91 The largest values occur at S band. Other examples of cross  section are given in Fig. 13.14, which plots the average radar cross section as a function of the  weight of the bird. 
 1 . 164 INTRODUCTION TO RADAR SYSTEMS  microwave combining circuitry.1•26 These are called multimodefeeds. The ust: of higher-order  waveguide modes in monopulse feeds to generate the required patterns results in feeds that are  of high efficiency, compact, simple, low loss, light weight, low aperture blockage, and excellent  boresight stability independent of frequency. 
 FORCE APPROACH TO DEFEAT NOISE JAMMING IS TO INCREASE THE RADARS TRANSMITTER POWER 4HIS TECHNIQUE  WHEN COU 
 D.W. Allan, H. Hellwig, P. 
 As stated previously, shipborne radars are validated as meeting IMO performance  standards by being independently type approved to technical standards issued by the  IEC. The IEC standards include defined methods of testing. For a given target and radar  antenna height, it is relatively easy to define and execute a test to determine that a point  source target with a specific echoing area is detected at a given range in a minimal  clutter field. 
 For low -grazing angle  a= a0 bcr b, sec tjJ where (Jo = radar cross section of the ground per unit area illuminated,  c5cr = along-track, or cross-range, resolution (equal to D/2 for a focused SAR), b, = range  resolution, and t/J = grazing angle. Substituting the above relations into Eq. (14.14) yields  Pav A;a0 b, sec t/J S/N = -8n:).kT0 Fn vR3 (14.15)  This is essentially the same equation as given by Cutrona2 and Harger.3  Equation (14.15) does not include the ambiguity constraints described previously. 
 2'0/ TECHNIQUES ALLOWS THE PERFORMANCE THAT WOULD BE ATTAINED IN THE ABSENCE OF THE CORRESPONDING %#-S TO BE RESTORED 4!2'%4 ./,/34 4!2'%43 4S S 4AVE S  0- 7 0/3 %22 M 6%,%22 MS       n         n       n  4!",%  3IMULATION 2ESULTS 7ITHOUT %#- 4!",%  3IMULATION 2ESULTS 7ITH 3/* AND 7ITHOUT ! 
 LOOKING AIRBORNE RADAR v  )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS   VOL    PP n     2 + 2ANEY  h4HE MAKING OF A PRECEDENT THE SYNTHETIC APERTURE RADAR 3!2  ON -AGELLAN v   6 
 KM SWATH  WIDTH  AND  ^n INCIDENCE  ALL IN THE PATTERN OF THE 3EASAT 3!2 4HE TWO %23 3!2S WERE  VIRTUALLY IDENTICAL %23 
 20. Holland, M. G., and L. 
 It is a  quarter wavelength thick and designed so that energy reflected from the front surface cancels  the energy which enters the material and is reOected from the inner surface. A destructive  interference absorber is analogous to the antiretlection coatings applied to optical lenses. It is  inherently narrowband. 
 Now inspite ofthewildly irregular nature of the noise voltage, the theory ofrandom processes applied tothis case. 36 THERADAR EQUATION [SEC. 2.10 (Vol. 
  REQUIRED A SUBSONIC AIRFRAME 4HE AIRFRAME IS COVERED WITH THIN ABSORBING MATERIAL WHOSE EDGES ARE SERRATED TO REDUCE REFLECTIONS WHERE HATCHES AND COVERS FIT INTO THE FUSELAGE " 
 With the passage of time, when the natural compression of the soil reaches its limit and the porosity ratio drops to the minimum, the deformation caused by the early external load and extravasation of the inner water in the soft soil ceases. Consequently, the subsequent deformation was mainly aﬀected by external environmental factors. According to precipitation data provided by the Fuoshan Meteorological Bureau, the annual precipitation in 2015 was 2055.2 mm, 20% higher than previous years. 
 The waveform repetition frequency (wrf) was 20 Hz. Noise (AO samples were taken at wrf/2, target samples (T) on a target peak, and approach (A) and recede (R) on the resonant ocean wave peaks; N, T, A, and R are plotted in Fig. 24.276. 
 MENT  OR MISSION PLAN  HIGH POWER DENSITY JAMMING BASED ON THE CORRESPONDING ON 
 Eng. Rept. 3648-1-T, 1961. 
 Other location schemes are given in Section 23.6. When separate transmit and receive antennas are at a single site, as is common in  CW radars, the radar has characteristics of a monostatic radar, and the term bistatic   is not used to describe such a system. In special cases, the antennas can be at sepa - rate sites, and the radar is still considered to operate monostatically. 
 RANGE SYSTEMS  SYNTHETIC APE RTURE PROCESSING TECH 
 (a)Vanetype;(b)risingsun,with alternate slotlengths. Fig.6.3.Theoutputpoweriscoupledfromthestabilizing coaxialcavity.Thecavityoperates intheTEollmodewiththeelectricfieldlinesclosedonthemselves andconcentric withthe circularcavity.TheRFcurrentateverypointonthecircumference ofthecavityhasthesame phase,sothatthealternate slotswhichcoupletothestabilizing cavityareofthesamephaseas required for1tmodeoperation. Theelimination ofthestrapsallowstheresonators tobe designed foroptimum efficiency ratherthanasacompromise between efficiency andmode control. 
 This backscattered energy is a function of the wavelength, the complex index of refraction of the particle, and the ratio 2ira/X, where a is the radius of the spherical particle and X is the wavelength. When the ratio 2ira/X — 1, the Rayleigh approximation10 may be applied, and cr, becomes CT1- = ^IATI2A6 (23.4) X where D1 is the diameter of the /th drop and ™2 i 2 \K\2= ^-^ (23.5) m2 + 2 where m is the complex index of refraction. At temperatures between O and 2O0C, for the water phase, and at centimeter wavelengths \K\2 * 0.93 (23.60) and for the ice phase \K\2 * 0.20 (23.66) Equation (23.3) can now be written as 5 N TI = 5JlJTI2^X (23.7) X 1=1 and the radar reflectivity factor Z defined as N Z ]?A6 (23.8) /=i In radar meteorology, it is common to use the dimensions of millimeters for drop diameters D1 and to consider the summation to take place over a unit vol- ume of size 1 m3. 
 TURE FROM THE RECTANGULAR ANTENNAS SO TYPICAL OF MOST SPACE 
 SCALE ROUGHNESS WAS ASSUMED TO CAUSE A  TILTING OF THE FLAT SURFACE TO WHICH THE  SMALL 
 The booster armature and regulating field increase the size and weight ofthe dynamotor, but the regulator itself can be considerably smaller than aseries regulator because itcarries only “the field current rather than the line current. 14.8. Vibrator Power Supplies.—If relatively small amounts ofpower arerequired, vibrator power supplies areuseful. 
 (See Fig. 14.8.) It is to be noted that the illuminator for the basic Hawk surface-to-air mis- sile system used a magnetron as the transmitter rather than a MOPA chain. Cost, availability, lower weight, and lower high-voltage requirements were all factors in the choice. 
 I.: Radar Horizon and Propagation Loss, Proc. IRE, vol. 45, pp. 
 -ADJAR  $ 'UYON  AND * 2IOM  h.ADIR LOOKING AIRBORNE RADAR  AND POSSIBLE APPLICATIONS TO FORESTRY v 2EMOTE 3ENSING %NVIRON  VOL   PP n    3 , $URDEN  * $ +LEIN  AND ( ! :EBKER  h0OLARIMETRIC RADAR MEASUREMENTS OF A FORESTED AREA  NEAR -T 3HASTA v )%%% 4RANS ON 'EOSC AND 2EMOTE 3ENSING  VOL   PP n    $ + "ARTON  h,AND CLUTTER MODELS FOR RADAR DESIGN AND ANALYSIS v  0ROC  )%%%  VOL     PP n    2 + -OORE  4RAVELING 7AVE %NGINEERING  .EW 9ORK -C'RAW 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.516x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 to various forms of contamination and distortion, many ionospherically induced,  so methods to deal with these have long been part of the radar signal processing   toolbox.135,136 Moreover, the need to deal with these deleterious effects has become  more pressing as the achievable dynamic range of receiving systems has increased,  revealing a greater variety of signal distortion mechanisms. 
 T. Ulaby, B. Brisco, and M. 
 -ISSION 2ADAR --2  IS DESIGNED TO DETECT AND  TRACK MORTARS  ARTILLERY  AND ROCKETS 4HIS RADAR USES A NONLINEAR &- SINE 
 TO 
 27, pp. 241–248, 1985. 123. 
 G.A.:Computer Control ofArrayRadar,Sperr.l'EllqineerillY Rel·iew,vol.18,No.4. Pl'.182.1.Winter.1%5. 117.Scheff.B.II..andD.G.Hammel: Real-time Computer Control ofPhasedArrayRadars.SlIppl.to I'JJ~Fram OilAc/'()sl'ace alldE!ecrrollic Srstellls. 
 The position accuracy of the filter can then be calculated using the formulas in  Table 7.3 and is shown in Figure 7.27. When the target is nonmaneuvering, accuracy,  as measured by the standard deviation of the predicted tracking state, improves mono - tonically as the tracking gain a decreases to 0. Conversely, when the target is per - forming the 1-g maneuver, accuracy, as measured by the lag (or bias) in the predicted  tracking state, improves monotonically as the tracking gain increases to 1. 
 CASE VALUE  ;= L O G3ENSITIVITY,OSS'ATED0HASE. 
 Figure 13.13  Coverage of an ACC sensor with close -range sensing (Courtesy A.D.C.)   13.3.2.2  Antenna Design   Today dielectric lenses are almost exclusively used for ACC Radar sensors.  In a few cases are   these full lenses and in other cases layered lenses.  There are also well -known antennas with  polarized lattices having double reflection at 45°. 
 PULSE CANCELER REQUIRES THE TRANSMITTER TO TRANSMIT ONLY TWO SUC 
 (2.11) 148.7 239.3 261.7 785.0 A decibel-logarithmic form of the range equation is sometimes useful. An equation of that type, corresponding to Eq. (2.11), is readily obtained as the al- gebraic sum of the logarithms of the terms of that equation (with appropriate mul- tipliers for the decibel format and for exponents), since it involves only multipli- cation, division, and exponentiation. 
 All of the proven radar systems developed prior to the war were in the VHF band. These low frequency radar signals are subject to severallimitations, but despite the drawbacks, VHF represented the frontier of radartechnology. Late in 1939, British physicists created the cavity magnetronoscillator which operated at higher frequencies. 
 The problem is addressed with pattern recognition techniques. 89. Sensors 2019 ,19, 1649 In this section, the information exploitation method is presented. 
 vol.  AI!S- I I. 111). 
 Wavelength (Frequency). There is ordinarily no problem in definition or evaluation (measurement) of the frequency to be used in the radar range equation. However, some radars may use a very large transmission bandwidth, or they may change frequency on a pulse-to-pulse basis, so that a question can exist as to the frequency value to be used for predicting range. 
 ch18.indd   58 12/19/07   5:15:20 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 MacArthur, “Pulse compression and sea-level tracking in  satellite altimetry,” Journal of Atmospheric and Oceanic Technology , vol. 6, pp. 407–438, 1989. 
 Since the output of the mixer . Tronsmilfing  antenna  ~ cw  ~ --,E-----J lransmifler  fo fo  Receiving  antenna Oscillator  ~f CW AND FREQUENCY-MODULATED RADAR 75  2d  detector Doppler  amplifier Indicator  Figure 3.4 Block diagram of CW doppler radar with nonzero IF receiver, sometimes called sideband  s11 perhet erod y11e.  consists or two sidebands on either side of the carrier plus higher harmonics, a narrowband  filter selects one of the sidebands as the reference signal. 
 TION REQUIRES DETECTIONS IN AT LEAST  OF THE  02&S WITH ALL 02&S CLEAR AT MAXIMUM  RANGE 4HE 02& SELECTION CRITERIA USUALLY REQUIRES THAT THE 02& SET IS  CLEARIN OTHER WORDS  AT LEAST A SPECIFIED NUMBER TYPICALLY   OF 02&S MUST HAVE AN ABOVE THRESHOLD RETURN ECHO FOR THE MINIMUM SPECIFIED TARGET FOR THE FULL SPECIFIED RANGE 
 This requirement  exists for either quadrature I, Q (in-phase, quadrature) sampling or direct sampling  with the I and Q data constructed after the A/D. The limiter must be designed to  minimize the conversion of amplitude to phase no matter how much the signal level  exceeds the limit level. If clutter saturates the A/D, the I, Q data is significantly cor - rupted. 
   '2/5.$ %#(/  £È°ÓÇ -ANY SYSTEMS USE DIGITAL WAVEFORM SYNTHESIS TO OBTAIN THE SWEPT WAVEFORM )F  DUAL ANTENNAS ARE USED AS SHOWN   THE OVERLAP OF THE BEAMS MUST BE CONSIDERED  3INGLE 
 When the process is repeated for each patch on the surface, a system of 2n linear homogeneous equations in 2n unknowns is generated. If the boundary conditions permit the decoupling of the equations, the number of unknowns may be halved (n equations in n unknowns). The coefficients of the resulting matrix involve only the electrical distances (in wavelengths) between all patches taken by pairs and the orientation of the patch surface normals. 
 See correction, AES-10, p. 168, January, 1974.  46. 
 Knittel, Phased Array Antennas , Norwood, MA: Artech House, 1972.  7. L. 
 34Theairseveralmetersabovetheseaisnotusuallysaturated sotherewill beagradual decrease inwatervaporpressure fromthesurfacevaluetotheambient valuewell abovethesurface.Thedecrease inwatervaporpressure isapproximately logarithmic, which contributes alogarithmic decreasing termtotheindexofrefraction. Theevaporation ductexistsovertheocean,tosomedegree,almostallofthetime.The heightoftheduct,whichisusuallywithintherangefrom6to30m,varieswiththegeographic location. season,timeofday,andthewindspeed.IntheNorthSeathemeanductthickness is about6 mwhileintropical regionsitisoftheorder10to15m.34IntheNorthAtlantic at Weather ShipD(44°N,4.OW)themedianvalueofductthickness (halftheductshavethickness oflesservalue)is10minthesummer and30minthewinter. 
 The basic ballistic missile defense problem  becomes more of a target recognition problem rather than detection and tracking.  The need for warning of the approach of ballistic missiles has resulted in a number of  different types of radars for performing such a function. Similarly, radars have been  deployed that are capable of detecting and tracking satellites. 
 C., et al.: Large Bistatic Angle Radar Cross Section of a Right Circular Cylinder, Electromagnetics, vol. 5, pp. 63-77, 1985. 
 Int. Comput. Conf., vol. 
 TION  AS IT MAINLY OPERATES AS A BROADCAST SYSTEM  BASED AROUND A  3ELF /RGANIZING 4IME  $OMAIN -ULTIPLE !CCESS 3/4$-!  COMMUNICATIONS PROTOCOL 4HE COMMUNICATIONS LINK  INCLUDING THE 3/4$-! DEFINITION  IS DEFINED BY THE )45  3HIPS AUTOMATICALLY  TRANSMIT CURRENT NAVIGATIONAL DATA AND OTHER INFORMATION ON 6(& MARINE 
 TEROMETER v )%%% *OURNAL OF /CEANIC %NGINEERING  VOL /% 
 Although this situation occurs infrequently  in nature, it still must be considered when assessing electromagnetic systems’ per - formance. For example, an Atlantic coast vessel traffic control radar located near the  entrance to the Delaware Bay observed a reduction in detection range from 37 to  17 km. Sometimes ships can be seen visually from the radar tower before they can be  observed on the radar screen. 
 31. Skolnik, M. I., J. 
 Boggs, W. L. Grantham, and J. 
 SPACE DISTANCE OF MORE THAN ONE WAVELENGTH 4O OVERCOME THIS  SLOTS ARE SPACED AT NOMINALLY HALF THE GUIDE WAVELENGTH BUT ARE ANGLED ALTERNATELY TO THE VERTICAL IN ORDER TO INDUCE THE NECESSARY PHASE REVERSALS )N PRACTICE  THE SLOTS ARE PLACED SLIGHTLY AWAY FROM HALF THE GUIDE WAVELENGTH SPACING TO AVOID SLOT 
 GYRATION IS CALCULATED ASSUMING THE hWEIGHTv OF THE SCATTERERS IS THEIR EFFECTIVE RADAR SCATTERING CROSS SECTION. °ÎÓ  2!$!2 (!.$"//+  4ARGET ANGLE NOISE IS TYPICALLY GAUSSIAN 
 AMBIGUITY FOR THE RADIAL VELOCITIES OF INTEREST &OR THIS CHAPTER  A PULSE DOPPLER RADAR IS CHARACTERIZED AS HAVING A 02& ANYWHERE WITHIN THE MEDIUM TO HIGH 02& REGIME THAT RESULTS IN AMBIGUOUS RANGE MEASUREMENTS DURING A COHERENT PROCESSING INTERVAL ! COMPARISON OF -4) AND PULSE DOPPLER RADARS IS SHOWN IN 4ABLE  0REVIOUSLY  UNDEFINED TERMS WILL BE DEFINED THROUGHOUT THE CHAPTER 4HE TABLE ASSUMES AN AIRBORNE RADAR APPLICATION DESIGNED TO DETECT OTHER AIRCRAFT 3UCH AN APPLICATION IS COMMONLY REFERRED TO AS AIR 
 like all spurious IF frequencies, arise from cubic or higher-order terms in the power-series model of the mixer. The available spurious-free bandwidth in any of the designated regions is roughly 10 percent of the center frequency or (H - L)IlQH. Thus receivers re- quiring a wide bandwidth should use a high IF frequency centered in one of these regions. 
 ,  &-angle tracking?' -53190- 94 A radar that tracks a target at a low elevation angle, near the  surface of the earth, can receive two echo signals from the target, Fig. 5.15. One signal is  rettected directly from the target, and the other arrives via the earth's siirface. 
 pp.352359.IEEEConference Publication no.105. 75.Hampton. R.L.T..andJ.R.Cooke: Unsupervised Tracking ofManeuvering Vehicles, IEEETrailS., vol.AES-9.pp197207.March. 
 Clutter Cell Area.42'51-59'73-85'89 The main-lobe bistatic clutter cell area^c is defined, in the broadest sense, as the intersection of the range resolution cell, the dopplcr resolution cell, and the bistatic main-beam footprint. The range and dopplcr resolution cells are defined by isorange and isodoppler contours, respectively. The bistatic footprint is the area on the ground, or clutter surface, common to the one-way transmit and receive beams, where the beamwidths are conventionally taken at the 3-dB points. 
 ETARY SURFACES  )N EACH OF THESE MEASUREMENTS  THE REFLECTIVITY DATA IS EXPRESSED IN  TERMS OF REFLECTED POWER  NOT R" ÓÎ°Ê 1 +1 
 V.: Detection Results for Scanning Radars E!nploying Feedback Integration, IEEE Trans ..  vol. AES-6, pp. 
 15. Pettengill. G. 
 Williamson, “Properties and applications of reflective-array devices,” Proc. IEEE , vol. 64,  pp. 
 34$ 
 202) that a = 1.2 for detection of signals by visual observation of cathode-ray-tube displays. Figure 2.2 is a plot of the Radi- ation Laboratory experimental results. The value 1.2 has subsequently been widely used for determining #n,opt m radar design and for computing CB in radar range prediction.11'12 However, North* has suggested that the a = 1.2 figure may be based on a misinterpretation of the Radiation Laboratory data. 
 Int. Conf.  Radar , Paris, France, May 1984, pp. 
 Equation (21.71), being a three-dimensional spectrum of an object, requires that the data be taken with an origin of coordinates and a coordinate system fixed with respect to the object being imaged. Hence the effect of translation and ro- tation of a moving object must be compensated in order to image that object. The three-dimensional spectrum is the proper format for storing radar data. 
 Numerous considerations enter inthe design ofaradar pulser; of primary concern arethenature oftheload, theoutput pulse voltage and current, the pulse duration, and the repetition rate. The operational problem faced bythe complete equipment will impose some specific requirements onthe pulser, with regard tosize, weight, supply voltage, etc.;such requirements may make itnecessary touse anotherwise less desirable design.. 356 THEMAGNETRON ANDTHEPULSER [SEC. 
 Thus the angle errors can be  averaged by operating the radar over a wide frequency band or by sweeping the RF frequency  and deducing the angle on the basis of the corresponding behavior of the error signal.46 It  turns out, however, that the bandwidth required to extract the target elevation angle is esesen­ tially the same required of a short pulse for separating the direct and reflected signals. Thus,  the bandwidths needed to eliminate the multipath error are usually quite large for most  applications.  The doppler frequency shift of the direct signal dilTers from that of the surface-reflected  signal. 
 W. J. Ince and D. 
 Sinceitisnotalwayspossible toknowtheexactnatureoftheerrorsthatmightbe encountered inaspecificantenna, theproperties oftheantenna mustbedescribed instatistical terms.Thatis,theaverage, orexpected, valueoftheradiation patternofanensemble of antennas ofsimilartypecanbecomputed basedonthestatistics oftherandom errors.The statistical description oftheantenna properties cannotbeappliedtoanyparticular antenna, butappliestothecollection ofsimilarantennas whoseerrorsarespecified bythesame statistical parameters. Theensemble average powerpattern;ofauniform arrayofMbyNisotropic elements arranged onarectangular gridwithequalspacing between elements canbeexpressed as109 MN If(B,4»12=P;e-,p Ifo(B,4»12+[(1+!!2)P~-P;e-J2J2:2:i;'n m=1n=1(8.24) wherePI!=probability ofanelement beingoperative (orthefraction ofthedements that remainworking) (j=phaseerror(described byagaussian probability densityfunction) 1.10(0,4>W=no-error powerpattern !!=amplitude error . imn=no-error currentatthemnthelement Thustheeffectofrandom errorsistoproduce anaveragepowerpatternthatisthesuperposi­ tionuftwoterms,similartoEq.(7.31)forthecontinuous aperture. 
 For example, if the beam is to be scanned anywhere within a cone defined by a . 334 INTRODUCTION TO RADAR SYSTEMS  half-angle of 45°, the number of elements required with triangular spacing is 13.4 percent Jess  than with square spacing. In this case. 
 PROPAGATING OCEAN WAVES ARE CAUSED PREDOMINANTLY BY THIRD 
 AP-12.  pp. 781 782. 
 Figure 8.9shows awhole setof replies from such abeacon, exposures having been made every few sweeps ofthePPI. The interrogations were at10cm, thereplies at1.5m. The principal reason forusing such abeacon rather than one that gives a microwave reply isthe relative simplicity ofthe low-frequency trans- mitter and antenna ofthe beaeon. 
 vol. A P-K. pp. 
 Skolnik (ed.), McGraw-[{ill  Book Co., New York, 1970.  2. Boot, H. 
 Appl. Earth Obs. G éoinf. 
 29 -38, 1966.  114. Webster, A. 
 Bol’shakov, Questions of the Statistical Theory of Radar , vol. II, Moscow:  Sovetskoye Radio, 1963, Chaps. 10 and 11. 
 SIZE DISTRIBUTION 4HE GENERALLY ACCEPTED EQUATIONS FOR ATTENUATION BY CLOUDS USUALLY SHOW THE MOISTURE COMPONENT OF THE EQUA 
 (a) Transversal proﬁle at LL’ in Figure 3a and ( b) geological distribution of the soft soil along the longitudinal direction of the Lungui Highway. 236. Sensors 2019 ,19, 3073 4.2. 
 Funding: This research received no external funding. Acknowledgments: The author is grateful for the scientiﬁc support given by Jean Eilek from New Mexico Institute of Mining and Technology and the anonymous reviewers for their fruitful comments, remarks and suggestions to improve the quality of the paper. Conﬂicts of Interest: The author declares no conﬂicts of interest. 
 Each pilot sees adifferent radial line indicating hisown plane. FIG. 718.—Schematic drawing ofTeleran rmesentationin anaircraft flying at11,000 ft. 
 The complex structure and dynamics of the ionospheric medium govern HF sky - wave propagation primarily through the space-time variation of the free electron  density distribution. A useful simplification is to regard the large-scale ionospheric  structure as defining the propagation geometry throughout the illumination volume,  whereas the dynamical processes impose their respective modulations on the transit - ing signals. Computational Aspects and Ray-tracing. 
 variable resistance tomaintain constant output voltage. The two types ofregulators commonly used inaircraft arethe carbon-pile and the finger types. Carbon-pile Regulator-s.-The carbon-pile regulator (Fig. 
 BAND JAMMING IS SIMULTANEOUSLY RADIATED ACROSS THE ENTIRE BAND OF THE RADAR SPECTRUM OF INTEREST 4HIS METHOD IS USED AGAINST FREQUENCY 
 Each has its strengths,  and the choice of which to use is highly dependent on the radar requirements. Each  will be discussed in turn. For solid-state systems, diodes are used and can be switched  in a fraction of a microsecond. 
 Receivers withmixerfront-ends usingSchottky-barrier diodesatroomtemperature have demonstrhted respectable noisefigures.Double-sideband noisefiguresof6.5dBcanbeob­ tainedat94GHz,8.5dBat140GHz,and11dBat325GHz.(Ithasbeensuggested thata 7-dAsingle-sideband noisefigureisachievable overthesewavelengths.)73 Evenlowernoise figuresarepossible withsupercooled J.osephsonjunctions operating atliquid-helium tempera­ tures.Therehasalsobeensignificant development ofhigh-gain antennas atmillimeter wave­ lengths. especially forradioastronomy.74 Unconventional transmission lineshavealsobeen developed.95 97 Thustheadvances incomponents madeinthepastaswellastechnology evidenttoeither sideofthemillimeter regiongivereasontobelievethatNaturehasnotruledoutattainment of adequate capabilities atmillimeter wavelengths. Unfortunately, thelimitedavailability ofsuitable millimeter wavecomponents isnotthe majorreasonforthelackofsignificant applications. 
 167  15.2 Automotive Radar ......................................................................................................... 167  15.3 Synthetic Aperture Radar ............................................................................................. 167  15.4 Antennas general .......................................................................................................... 
 BEAM AND SIDELOBE CLUTTER AS WELL AS JAMMING  . 
 140. M. W. 
 In  most cases, it will not be necessary to explicitly perform an integration to evaluate the  Fourier transform or inverse Fourier transform.Characteristic Value Transmit LFM bandwidth 1175 to 1375 MHz Reference LFM bandwidth 1665 to 1865 MHz* Transmit waveform swept bandwidth, B 200 MHz Reference waveform swept bandwidth, Bref 200 MHz*  Transmit pulsewidth, T 1000 µs Reference pulsewidth, Tref 1000 µs* Transmit waveform LFM slope 0.2 MHz/µs (up-chirp) Compressed pulsewidth (–3 dB), t3 3.75 ft Time-bandwidth product, TB 200,000 Time sidelobe level –30 dB Target range window 240 ft Number of range samples 400 Range sample spacing 0.6 ft First IF (at output of correlation mixer) 490 MHz Second IF 60 MHz Stretch processing bandwidth, Bp 100 kHz A/D converter sampling frequency 1 MHz (in I and Q baseband channels)TABLE   8. 9 Cobra Dane Wideband Pulse Compression System Characteristics ( adapted from Filer  and Hartt67 © IEEE 1976  ) * Excludes pulsewidth and swept bandwidth extension due to 240-ft range window  1 Fourier transform (spectrum) of  signal x(t) X f x te d tj( ) ( ) = −∞∞ −∫2πft  2 Inverse Fourier transform of  spectrum X(  f  ) x t X f e d fj( ) ( ) = −∞∞ ∫2πft  3 Convolution of signals x(t) and y(t) y t x t h t x h t d x t h( ) ( ) ( ) ( )( ) ( )= ∗ = − = − −∞∞ −∞∞ ∫ ∫τ τ τ τ ( ( )τ τd  4 Filter frequency response H(f) = Y(f)/X(f)  5 Euler’s identity   e jjθθ θ = +cos s inTABLE   8. 10 Signal Analysis Definitions and Relationships ch08.indd   36 12/20/07   12:51:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Lee, “MPAR program  overview and status,” presented at 23rd Int. Conf. on Interact. 
 W. JelITs: Design of MTI Filters with Staggered PRF: A  Pole-Zero Approach, Proc. I EE, vol. 
 Allthe power goes into thereceiver. Inonevariation ofthebasic scheme just outlined, thereceiver branch joins theantenna line inaseries rather than inashunt T. Then theTR switch must beahalf wavelength rather than aquarter wavelength from the junction. 
 From Eq. (2.4) it is clear that Bn directly affects the noise level in the receiver output. In general it also affects the signal, but not necessarily in the same manner as the noise is affected, because the signal spectrum is not usually uniform. 
 Since none ofthe tubes that can deliver laTge currents has either a second control electrode orasharp suppressor cutoff, itiscustomary to use screen gating when the current requirements arehigh. Inthecase of video signals, the tube must have a very sharp cutoffonthe signal grid; even then itisusually necessary to choose between anextreme bias, which sacrifices gain atlow signal ampli- tudes. and alesser one. 
 Since an m-sequence takes on all possible states except the zero state, the initial state of  the shift register does not affect the content of the sequence, but will define the starting point of  the sequence. A different sequence is obtained with different feedback connections. (The  number of stages connected modulo two must be even since an odd number of modulo-two  additions taken from the all-ones state will produce a one for the next term and the continued  generation of the all-ones state. 
 ULE ARE KNOWN  PULSE CHASING CAN BE CONSIDERED TO REDUCE THE MULTIBEAM COST PEN 
 NING ARE THEN POSSIBLE  INCLUDING THE BEAM 
 213 small compared with the size ofthe obstacle, toput itvery crudely. There issome spreading ofthis sort, ofcourse, and itisaphenomenon upon which agood deal oftheoretical effort hasbeen expended. Methods have been developed forcalculating theintensity oftheradiation inthe “diffraction region,” that is,beyond thehorizon (Vol. 
 One of the bipolar video outputs, /, is the component that is in phase with the reference oscillator. The other bipolar video output, Q, is in quadrature with the reference oscillator. The two bipolar video signals are sam- pled for each range cell and converted to digital representation by the A/D con- verters. 
 (25.7) can be approximated as . cMrt RR - ——- (25.8)1 + sin 0/e This approximation does not require an estimate of L. The error in Eq. 
 680–685, September 1973.  88. L. 
 The dashed circle represents the path described by the center of the beam as it is scanned. The radius of the dashed circle is p, the offset angle. The compromise that must be made in choosing p is between the loss of signal or antenna gain Lk (crossover loss) and the increase in angle sensitivity ks of the angle-sensing circuits. 
 Figure 25.38 shows a three-stage CIC decimation filter, and its frequency  response before and after decimation by 8 is shown in Figure 25.39 a and b, respectively.  Note that the aliased components are significantly reduced in amplitude, compared to the  single-stage CIC filter response, and the main passband has more attenuation toward the  edges. In typical applications, a CIC decimator is followed by a FIR lowpass filter and a  final decimation by 2. 
 852–869, 1947.  4. J. 
 Liu, Y.B.; Li, N.; Wang, R.; Deng, Y.K. Achieving high-quality three-dimensional InISAR imaging of maneuvering via super-resolution ISAR imaging by exploiting sparseness. IEEE Geosci. 
 Ideal mixers in a superheterodyne receiver act as multipliers, producing an output proportional to the product of the two input signals. Except for the effect of nonlinearities and unbalance, these mixers produce only two output frequencies, equal to the sum and the difference of the two input frequencies. Product mixers, although common at intermediate frequencies, are not generally available for RF520 25 -1,0 660 -82 -5 771300 -6 24 6 -88 -16 72300 15 18 5 73 +5 7824K 33 12 (-73) (+7) (80) 11 8811 83O 78O (80) 200 100 20 57100 50 17 552 1 O 782 1 O (80)Antenna Trans-line RF amplifier Mixer Filter Log detector Noise temperature of component Gain of component* Total gain to input Noise- temperature contributionreferred to antenna Overall RX bandwidth Boltzmann's constant Narrowband noise level *K dB dB System 838 K 29.3 dB K 63.0 dBHz 92.3 -198.6 -106.3 dBm Maximum signal capability Dynamic range to distributed targets"^ Bandwidth x time of point targef T Dynamic range fo point target "*" Bandwidth of receiver1" Ratio to overall receiver bandwidth r Wideband- noise vulnerability1" Dynamic range to wideband noise "I"dBm dB dB dB MHz dB dB80 75-1.0 -106 -107 11 11 . 
 Radars with "moderate"  resolution might require only enough improvement factor to deal with the median clutter  power, which may be 20 dB less than the average clutter power.45 According to Shrader a  medium-resolution radar with a 2 µs pulse width and a 1.5° beam width, is of sufficient resolution  to achieve a 20 dB advantage over low-resolution radars for the detection of targets in ground  clutter.50  Equipment instabilities. Pulse-to-pulse changes in the amplitude, frequency, or phase of the  transmitter signal, changes in the stalo or coho oscillators in the receiver, jitter in the timing of  the pulse transmission, variations in the time delay through the delay lines, and changes in the  pulse width can cause the apparent frequency spectrum from perfectly stationary clutter to  broaden and thereby lower the improvement factor of an MTI radar. The stability of the  equipment in an MTI radar must be considerably better than that of an ordinary radar. 
 Thus, ifthisrestriction isimposed, three brushes and three wires can beeliminated bymaking aYconnection. Ifa synchro with a2-phase rotor isused asareceiver, itsinduced voltages 1Inthissense theword “phase” refers torotation oftherotor rather than tothe internal phase ofanysignal being transmitted.. SEC.13.4] ANGLE-DATA TRANSMITTERS 489 willbeproportional tothesine and tothecosine ofthedifference ofthe twoangles, asinthe2-phase case. 
 TOR (OWEVER  THIS FACT ALONE DOES NOT ENSURE THAT THE TRANSMITTED WAVEFORM STARTS AT THE SAME 2& PHASE ON EVERY PULSE  WHICH IS A REQUIREMENT FOR COHERENT SYSTEMS  &)'52%   0HASE SHIFTS INFERRED BY VARIOUS TWIDDLE FACTORS                          .   2!$!2 $)')4!, 3)'.!, 02/#%33).'   Óx°Îx #ONSIDER A SYSTEM WITH A  
 $ AIRCRAFT &IGURE   USES !%7 RADAR AS THE PRIMARY   SENSOR IN ITS AIRBORNE TACTICAL DATA SYSTEM 4HESE RADARS WITH THEIR EXTENSIVE FIELD OF VIEW ARE REQUIRED TO DETECT SMALL AIRBORNE TARGETS AGAINST A BACKGROUND OF SEA AND LAND CLUTTER "ECAUSE THEIR PRIMARY MISSION IS TO DETECT LOW 
 The unambiguous doppler frequency or Nyquist frequency for a fixed pulse-repetition-frequency (PRF) radar is given by A/= ± PRF/2 (23.21)TABLE 23.4 Correction Factor (Multiplicative) for Rainfall Attenuation* Precipitation rate p, mm/h 0.25 2.5 12.5 50.0 150X, cm 0.5 1.25 3.2 10.0 0.5 1.25 3.2 10.0 0.5 1.25 3.2 10.0 0.5 1.25 3.2 10.0 0.5 1.25 3.2 10.0O0C 0.85 0.95 1.21 2.01 0.87 0.85 0.82 2.02 0.90 0.83 0.64 2.03 0.94 0.84 0.62 2.01 0.96 0.86 0.66 2.001O0C 0.95 1.00 1.10 1.40 0.95 0.99 1.01 1.40 0.96 0.96 0.88 1.40 0.98 0.95 0.87 1.40 0.98 0.96 0.88 1.40180C 1.0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .0 .03O0C 1.02 0.90 0.79 0.70 1.03 0.92 0.82 0.70 1.02 0.93 0.90 0.70 1.01 0.95 0.99 0.70 1.01 0.97 1.03 0.704O0C 0.99 0.81 0.55 0.59 1.01 0.80 0.64 0.59 1.00 0.81 0.70 0.59 1.00 0.83 0.81 0.58 1.00 0.87 0.89 0.58 . *From Saxton and Hopkins.34 where PRF is the pulse repetition frequency. The unambiguous range interval is given by A^ = 2^F (23'22) and the product A/Ar is simply A/Ar = ^ (23.23) Since the doppler shift/and the target radial velocity v are linearly related by the expression v = I/ (23.24) it follows that the product of unambiguous velocity and unambiguous range is AvAr = ^ (23.25)4 and is maximized by maximizing X, the transmitted wavelength. 
 DEPENDENT    TRANSLATION ERRORS 2ANGE OSCILLATOR FREQUENCY $ATA TAKEOFF ZERO SETTING2ANGE RESOLVER ERROR)NTERNAL JITTER $ATA GEAR NONLINEARITY AND BACKLASH $ATA TAKEOFF NONLINEARITY AND GRANULARITY2ANGE OSCILLATOR INSTABILITY 4ARGET 
 REFERENCES  1. A. H. 
 22.2 SBRSYSTEMSCONSIDERATIONS Types of SBR. There are three types of radar that have been and can be based in space. SBR that is typical of Type I is the small, short-range rendezvous radar such as those used on the Shuttle, Apollo, and Gemini programs. 
 0OL 4HE MULTI 
 This factor is "the predetection signal- to-clutter ratio that provides stated probabilities of detection and false alarm on a display; in moving-target-indicator systems, it is the ratio after cancelation or doppler filtering."10 The clutter visibility factor is the ratio by which the target signal must exceed the clutter residue so that target detection can occur without having the clutter residue result in false-target detections. The system must provide a threshold that the targets will cross and the clutter residue will not cross. 75.5 IMPROVEMENTFACTORCALCULATIONS Using Barton's approach (Ref. 
 They are marked in Figure 18b. The point o in Figure 18b is the rotation center. We deﬁned the height of rotation plane to be 0 m. 
 The glacier is an 11 km long, land-terminated glacier with an area of  35 square km. The glacier depth starts at 30 meters and increases down to 250 meters.  In the beginning of the profile, only the bottom echo is seen. 
 XIIIC and Mk. XIIID would be developed for the Sunderland and Warwick, respectively, using the scanner type 85 (re ﬂector size 36 ″×27″) which was to be stabilised against aircraft pitch and roll. These developments did not take place but ASV Mk. 
 Forafour-bitphaseshifter,covering 360°,theminimum number ofdiodesneededintheperiodically loadedlineis32,theswitched linerequires 16,andthe hybrid-coupled circuitneedsonly8.Thetheoretical peakpowercapability oftheswitched line istwicethatofthehybrid-coupled circuitsincevoltagedoubling isproduced bythereflection ,-~-If-~-:-~-I~t~__ 4'--.r---~---'--_~--<> Inpul Oulpul Susceptances Diode switches Figure8.8Periodically loaded-line phaseshifter.. 290 INTRODUCTION TO RADAR SYSTEMS  in the hybrid circuit. The switched-line phase shifter has the greatest insertion loss, but its loss  does not vary with the amount of phase shift as it does in the other two types of circuits. 
 I (1985).  3 G. S. 
 Centerof torus\ L~ ....."\ (motteed positionsGenerating parabola Figure7.16Principle oftheparabolic-torus antenna.. Tlie advantage of the parabolic torus is that it provides an economical method for rapidly  scanning the beam of a physically large antenna aperture over a relatively wide scan angle witti  110 deterioration of tile pattern over tliis angle of scan. Its disadvantages are its relatively large  pliysical size wlien cotill>ared witli other means for scaliriitlg arid the large sidelobes obtained  in intermediate planes. 
 TIONS FROM SEVERAL DIFFERENT STATIONARY CLUTTER POINTS THAT HAVE BEEN ASSOCIATED TOGETHER OVER TIME TO CREATE A FALSE MOVING TRACK 4HE APPROACH FOR PREVENTING FALSE TRACKS ON OBJECTS NOT OF INTEREST IS TO ACTUALLY  DEVELOP TRACKS ON ALL OF THEM BUT THEN OBSERVE THEM LONG ENOUGH TO CLASSIFY THEM AS UNWANTED )N THE CASE OF THE BIRD  ONE WOULD GATHER ENOUGH DETECTIONS TO IMPROVE THE VELOCITY ACCURACY OF THE TRACK SO THAT IT IS CLEAR WHETHER THE TRACK IS OF INTEREST OR NOT 4HUS  ONE DESIRES TO DELAY THE DISCLOSURE OF A TRACK UNTIL ENOUGH TIME HAS PASSED TO CLASSIFY IT ACCURATELY 4HIS ACCURACY CAN BE DETERMINED BY  4 OBS  THE AMOUNT OF TIME OVER  WHICH THE OBJECT IS OBSERVED AND BY BASIC PARAMETERS OF THE RADAR 4   THE TIME BETWEEN SUCCESSIVE DETECTIONS R    THE ACCURACY IN A PARTICULAR DIMENSION OF INTEREST -   THE NUMBER OF DETECTIONS USED IN FORMING THE TRACK.   4 OBS  4       WHICH IS THE NUMBER OF DETECTION OPPORTUNITIES 4HE VELOCITY ACCURACY IS GIVEN BY THE FOLLOWING EQUATION  SS V4. 
 3. Synthetic and Inverse Synthetic Aperture Radar Issues Problems of synthetic aperture radar imaging are widely discussed in the recent literature. Diﬀerent modeling and imaging techniques including dominant scattering points and facets models, Fourier transforms, and phase compensation methods are in the focus of the authors’ attention. 
 The value of sang for a complex target is essentially a fixed value regardless of RF  frequency, if a target span of at least several wavelengths is assumed and is independent  of the rate of random motion of the target. However, as described later, the spectral  distribution of angle-noise power is directly affected by radar frequency, atmospheric  turbulence, and other parameters.– a = 0.966+ 29 L12L 11L 10L 9L 8L 7L 6L 5L 4L 3LREFLECTORS POINTING ERROR (UNITS OF TARGET SP AN L) 2L LL 0– a = 0.866 – a = 0.682 0 40 8 0 120 160 200 f (degrees)240 280 320 360 FIGURE 9.20  Apparent location of a dual-source target as a function of relative phase f for different  values of relative amplitude a measured with a tracking radar ( Figure 5 from Howard37) *  Radius-of-gyration is calculated assuming the “weight” of the scatterers is their effective radar scattering cross section. ch09.indd   31 12/15/07   6:07:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Data extrapolation for high resolution radar imaging. IEEE T rans. Antennas Propag. 
 Kitlctio~tr, I,. N.: " Kndnr Sysrcnl I'ngi~iccrir~g," MIT Radiation Laboratory Series, vol. 1. 
 When the received  echo signal from the target is large compared to noise, this may be written as  Output of the matched filter= f 00  sr(t)s•(t -TR) dt  -oo (11.46)  where s,(t) is the received signal, s(t) is the transmitted signal, s•(t) is its complex conjugate,  and T'R is the estimate of the time delay (considered a variable). Complex notation is assumed  in Eq. (I l.46). 
     PP n     6 4WERSKY  h/N THE SCATTERING AND REFLECTION OF ELECTROMAGNETIC WAVES BY ROUGH SURFACES v  4RANS )2%  VOL !0 
 TRACKING ERROR AS AFFECTED BY THE SIGNAL 
 !NALOGUE #ONVERTER $!2 $IGITAL !RRAY 2ADAR $%#- $ECEPTIVE %#- $& $IRECTION &INDING $O! $IRECTION OF !RRIVAL $OF $EGREE OF FREEDOM $2&- $IGITAL 2ADIO &REQUENCY -EMORY $4O! $IFFERENCE 4IME OF !RRIVAL %- %LECTROMAGNETIC %! %LECTRONIC !TTACK %##- %LECTRONIC #OUNTER 
 Thus, even fora1°beam, thedisplay resolution exceeds thefundamental resolution forallpoints farther from the origin than one-third ofatube radius. The cathode-ray tube isusually notthelimiting factor inover-all angukzr resolution, although incertain cases ofaccurate range measurements or ofobservations ongroups ofaircraft orships atlong range, better range resolution onlong-range displays would beuseful. Frequently, however, theneed forhigh disperm”on requires expanded displays quite apart from question ofresolution. 
 A. Guissard, “Meuller and Kennaugh matrices in radar polarimetry,” IEEE Transactions on  Geoscience and Remote Sensing , vol. 32, pp. 
 Ingeneral, beacon signals donot vary asmuch between particular values ofrange, donot cut offasabruptly with increasing range, and donot give asdeep interference minima asradar signals do. Azimuth.—One further consequence oftheseparation ofthetwo links isthat thescanning sector through which beacon replies areobtained is limited either inthe interrogation link orinthe reply link according to circumstances. Equation (1)becomes more generally (5). 
   
 CT-4, pp. 41-53,  June, 1957.  1.4. 
 BAND RADARS 4HEY ARE OFTEN DUAL 
 Conv. Record, vol. 6, pt. 
 Ê /Ê/ 
 1tll) ofmerit.Amoresuitablereciprocal devicethatovercomes thelimitations ofprevious recipro­ calferritephaseshiftersinthedllal-mode phaseshifterbasedontheprinciple oftheFaraday rotor.25.33.35-37 Itiscompetitive withthetoroidphaseshifter,especially atthehighermicro- wavefrequencies. ,~ Inthedual-mode phaseshifterthelinearlypolarized signalinrectangular waveguide at theleft-hand portinFig.8.13isconverted tocircularpolarization byanonreciprocal circular polarizer (aferritequarter-wave plate).IntheFaraday rotatorportion, theappliedlongitu­ dinalmagnetic fieldrotatesthecircularpolarization, imparting thedesiredphaseshift.The circularpolarization isconverted tolinearbyasecondnonreciprocal polarizer. Asignal incident fromtherightisconverted tocircular polarization oftheopposite sensebythe nonreciprocal quarter-wave plate.However, sinceboththesenseofpolarization and thedirection ofpropagation arereversed, thephaseshiftforasignaltraveling fromrighttoleft isthesameasthatfromlefttoright.TheferriterodoftheFaraday rotatorismetallized to formafullyloadedwaveguide andisaccessible forheatsinking. 
 Moreover, physical optics shows no dependence on the polarization of the  incident wave and yields different results when the receiver and the transmitter are  interchanged. These effects contradict observed behavior. Finally, it errs by wider mar - gins as the direction of observation moves farther away from the specular direction. 
 Queen, F. D.: Radar Cross Sections or the T-38 Aircraft for the Head-On Aspects in L, S, and X  Bands, Nal'al Researclt Lahoratory' Report 7951, Jan. 8, 1976. 
 M.: Survey of Airborne Microwave Refractometer Measurements, Proc. IRE, vol 43,  pp. 1405-141 1, October, 1955. 
 S. J. Anderson and Y.I. 
 and G. R. Cooper: Measurement of Distributed Targets with the Random Signal  Radar. 
 TION AT THE INPUT TO EACH PHASE SHIFTER 4HE RELATIVE PHASE EXCITATION CAUSED BY THESE FEEDS IS A KNOWN FUNCTION OF FREQUENCY )N THESE CASES  THE COMPUTER MUST PROVIDE A CORRECTION BASED ON THE LOCATION OF THE ELEMENT IN THE ARRAY AND ON THE FREQUENCY OF OPERATION &OR A LARGE ARRAY WITH THOUSANDS OF ELEMENTS  MANY CALCULATIONS ARE REQUIRED TO  DETERMINE THE PHASING OF THE ELEMENTS 4HESE CALCULATIONS MUST BE PERFORMED IN A SHORT PERIOD OF TIME 4HE USE OF THE ORTHOGONAL PHASE COMMANDS  M4 XS  N4YS HELPS TO  MINIMIZE THESE CALCULATIONS /NCE THE ELEMENT 
 1960.  15. Barton, D. 
 Tech. Rept. 381, March 1965. 
 Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 12.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 where the eccentricity e of the hyperboloid is given by  e = sin[(yv + yr) / 2] / sin[( yv − yr) / 2]  The equivalent-paraboloid20 concept is a convenient method of analyzing the radia - tion characteristics using a single reflector “equivalent” model. This method utilizes  a paraboloid of equal diameter, but a larger focal length to model the dual-reflector  Cassegrain system. 
 J. M. Hudnall and S. 
 ~II.I.LIY is a two-dimensional configuration of elements arranged to  lie it1 a plane. The planar array may be thought of as a linear array of linear arrays. A broatlside  irrrii!. 
 The optical path length through each of the zones is one  wavelength less than the next outer zone.  Although zoning reduces the size and weight of a lens, it is not without disadvantages.  1)ielcctric lenses are normally wideband; however, zoning results in a frequency-sensitive  device. 
 rating,FoToperation below 10,OOQ ftwith blast cooling, 1000 w.areohtsimable. iIncludes weight ofexternal r-ffilter and 12-pf series condenser. See Figs. 
 CAPILLARY WAVES BOTH WIND 
 Inadequate dynamic range makes the radar receiver vulnerable to interference,  which can cause saturation or overload, masking or hiding the desired signals.  A tabular format for such a computation (a typical example of which is shown in  Table 6.1) will permit those components that contribute significant noise or restrict  the dynamic range to be quickly identified. “Typical” values are included in the  table for purposes of illustration. 
 Barrett, “An efficient method for the estimation of the frequency of  a single tone in noise from the phases of discrete Fourier transforms,” Signal Processing , vol. 11,  pp. 169–177, 1986. 
 BASED AND AIRBORNE AIR 
 To acquire track, intelligence may be passed on an open-loop basis from the doppler filter bank, if one is available, or the VCO may have a sawtooth or triangular voltage applied to produce a programmed search. Search is stopped when the output registers the desired target. Coding signals may be employed to aid in the detection and the stopping. 
 The setdescribed here had anantenna aperture 25ftwide and operated inthe 10.7-cm wavelength region, giving abeamwidth of approximately 1.00. “Itwill beofinterest toseehow fardevelopment toward increasingly sharper beams might usefully becarried, and toestablish asclosely as possible the optimum beamwidth foralong-range air-surveillance set. Itcan readily beshown that alower limit, and therefore anoptimum value, exists, entirely apart from questions ofmechanical difficulty. 
 PLANE DATA IS SHOWN IN BOLD TYPESEE SUBSEQUENT TEXT    AFTER - - 7EINER  #HAPTER   COURTESY 3CI4ECH   #ONTINUED  . ÓÎ°ÓÈ  2!$!2 (!.$"//+  )N ADDITION TO THIS DATABASE  BISTATIC REFLECTIVITY MEASUREMENTS HAVE BEEN MADE AT  OPTICAL AND SONIC WAVELENGTHS AND OF BUILDINGS  AIRPORT STRUCTURES  AND PLAN 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 Frequency Diversity. 
 56. Pawsey, J. L., and R. 
 Thus, if the slope distribution of such facets is known, the fraction normal to a given diverging beam can be established, and from this the return can be obtained. Geometric optics assumes zero wavelength, and so the results of such a theory are wavelength-independent, clearly not in accord with obser- vation. The facet model for radar return is extremely useful for qualitative discus- sions, and so modification to make it fit better with observation is appropriate. 
 Manual tuning was also very dif ﬁcult over a calm sea in the absence of strong targets or land return, although the wavemeter (echo box) could be used forthis purpose. The advent of a klystron that could be tuned by altering its re ﬂector voltage meant that automatic tuning could be introduced. TR 3519B in ASV Mk. 
 (See Sec. 9.12 and Fig, 9.16, ). SEC. 
 The primary use one finds for GTD is in defining the antenna's operation in the back hemisphere, but for many antennas the irregularity of the edges requires an agonizingly complex description of the antenna. This is often found to be impractical to implement into a GTD analysis. Sometimes simple analyses are performed at special angles of interest. 
 L11204, June 10, 2005. 148. M. 
 J. C. Wiltse, S. 
 2 2ECOMMENDATION  "ECAUSE RACONS NORMALLY FORM ONLY ONE SUBSYSTEM OF AN !TO. THEY THEREFORE NEED TO  BE SMALL IN SIZE AND POWER EFFICIENT SINCE THEY ARE RARELY CONNECTED TO A MAIN POWER SUPPLY 4HEY OFTEN OPERATE IN  AN EXTREME ENVIRONMENT  SUCH AS O N A BUOY BUFFETED BY  THE SEA 2ACONS ARE SPECIFIED TO MEET AN EXTENDED OPERATIONAL TEMPERATURE RANGE OF n TO  # -ODERN RACONS OPERATE BY DETECTING AN INCIDENT PULSE AND THEN MEASUR 
 Pulse Repetition Rate The pulse repetition rate (PRR) determines the maximum measurable range of the radar. Ample time must be allowed between pulses for an echoto return from any target located within the maximum workable range of thesystem. Otherwise, echoes returning from the more distant targets areblocked by succeeding transmitted pulses. 
 MINES v PRESENTED AT 30)% $ETECTION AND 2EMEDIATION 4ECHNOLOGIES FOR -INES AND -INELIKE  4ARGETS 8))  /RLANDO  &,  !PRIL   ' $ENNISS h3OLID 
 This configuration has been called a mirror scan antenna (by the  Naval Research Laboratory), polarization twist Cassegrain and flat plate Cassegrain (by  Westinghouse Electric), and a parabolic: reflector with planar auxiliary mirror (by Russian  authors138). The parabolic reflector is made up of parallel wires spaced less than a half-. Fixed porobol,c  reflector  with porollel  \  ?.8  \  flay polh ... 
 J. Netherway and Carson, C. T., “Impedance and scattering matrices of a wideband HF phased  Array,” J. 
  4HE DESIGN OF LOW CROSS 
 K.: " Radar System Analysis." Prentice-Hall, Inc., Englewood Cliffs, N.J., 1964.  MTIANDPULSE DOPPLER RADAR149 17.Brennan, L.E.,andl.S.Reed:Optimum Processing ofUnequally SpacedRadarPulseTrainsfor Cluller Rejection. IEEETrails..vol.AES-4.pp.474-477, May,1968. 
 With the exception of thunderstorms, ducting is essentially a fine-weather phenomenon  As tropical (but not equatorial) climates are noted for their fine weather, it is not sirrprising to  find the most intense ducting occurring 'in such regions.32 In temperate climates ducting is  more common in summer than in winter. It does not occur when the atmospllere is well nlixcd,  a condition generally accompanying'poor weather. When it is cold, rough, stormy, rainy, or  cloudy, the lower atmosphere is well'stii-red' up and propagation is likely to be normal. 
 higher-order components appearatj1.fd.fird.etc.The appearance ofhigher-order components canbeusedasameasure ofthewindspeed.buta moreusefulmeasure isthemagnitude ofthecontinuum aboutzerodoppler relativetothe magnitude ofthelargerresonant spectral line.(Thecontinumum between thetwospectral linesisdetermined bysecond-order scattering fromsetsofwavesthatformcorner retlectors.24)Iflandclutterispresentintheradarresolution cellalongwithseaclutter.orifit enterstheradarviatheantenna sidelobes. therewiJlbeaspectralcomponent atzerofrequency whichcandegrade theusefulness ofthismeasurement. Whentheseaissaturated. 
 Figure 11. Histogram of focused images amplitudes comparison. 3.3.2. 
 20. Rudnick, P.: The Detection of Weak Signals by Correlation Methods, J. Appl. 
 Microwave  lenses have also found some radar application, as have mechanically rotated array antennas.  The electronically scanned phased array, described in Chap. 8, is an antenna with unique  properties that has been of particular interest for radar application. 
 llltraviolet Radiation, and Radiation from Lasers and Television Receivers-An An-  rlotated flihliograplly." [J.S. Ijcpt. of Health, Education, and Welfare, Public Health Service Publica-  tion no. 
 # 
 75, Bruxelles, Belgium, 1978. 25. “Propagation in Non-ionized Media,” International Telecommunication Union, International  Radio Consultative Committee (CCIR), vol. 
 This is tracking performed by a sur - veillance radar. It can have a very large number of targets in track by using the  measurements of target locations obtained over multiple scans of the antenna.  Its data rate is not as high as the STT. 
 Odlum, W. J.: Selection of a Phased Array Antenna for Radar Applications, I EEE Truns, vol. AES-3,  no. 
 RADAR CLUTIER 515  85. Beasley. E.W.: Effect of Surface Reflections on Rain Cancellation in Radars Using Circular Polariza­ tion. 
 SCAN 
 SEC.17.7]GENERAL METHODS OFRELAYING SINEANDCOSINE 701 closed allsignals (video and interference) areexcluded until theflip-flop returns toitsstable condition shortly before thenext basic pulse. 17.7. General Methods ofRelaying Sine and Cosine.-A complete description ofanangle can begiven byexpressing itssine and itscosine inthesame units. 
 IO Recirculating-delay-line integrator, or feedback integrator, k loop gain < I. (a) single  delay loop; (h) double loop; (c) two-pole filter.  dela_r-line imegrator. 
 These areshown forarepresentative case inFig. 6.19. NullReadings. 
 For blind frequencies  € fd=n⋅1 T=n⋅fblind results in a non - detectable Doppler frequency.  . Radar System Engineeri ng Chapter 8 – Pulse Radar  54        Figure 8.7  Blind speed. 
 194. D. H. 
 The military need for radar has  probably been its most important application and the source of most of its major  developments, including those for civilian purposes. The chief use of military radar has been for air defense operating from land, sea,  or air. It has not been practical to perform successful air defense without radar. 
 ALONE RADAR DESIGNED FOR OPERATIONAL USE IT DOES NOT HAVE TO TIME 
 32. TABLE 22.8 OMV Radar CharacteristicsSBR orbit, nmi 450 900 56005-year total dose, rads (Si); aluminum shielding thickness 15 mils 2(1O)5 2(1O)6 6(1O)625 mils 6(1O)4 4(1O)5 4(1O)650 mils 2(1O)4 2(1O)5 (1O)6 Frequency PRF Pulse width Transmitter peak power Receiver noise figure Antenna Antenna size Antenna gain and beamwidth Search scan Angle accuracy (3a) Range accuracy (3<r) Range rate accuracy (3<r) Deployed assembly weight Inboard assembly weight Electronics volume Prime power9.5 to 9.8 GHz 6.67 kHz 0.05,0.2, 1.5, and 15 ^s 2 W (GaAs FET with « 30-dB gain) < 4 dB, GaAs FET LNA Planar slotted array, linear polarization 14 by 15 by 1 in 30.5 dB (at 9.65 GHz) and 5.0° ± 20° cone, with 5-min scan time 20 mrad Greater of 20 ft or 2 percent of range Greater of 0. 1 ft/s or 2 percent of range rate 26 Ib 50 Ib (redundant total) « 2 ft3 (redundant total) <60W . 
 13.21 Asthesignal level increases, thelast stage saturate sandcancontribute nomore. Bythis time, however, the contribution from the preceaing stage has become appreciable and the output continues toincrease, but atalower rate than that occurring when the gain ofthe last stage was included. Eventually the second stage saturates, and the gain drops tothat from thenext preceding stage, and soon. 
 BACK RATIOS  SO THE RISK OF SIGNAL MASKING BY BACKLOBE CLUTTER CANNOT BE IGNORED &OR LINEAR ARRAYS  OFFSETTING THE TRANSMIT AND RECEIVE ARRAY BORESIGHTS IS A MODERATELY EFFECTIVE MEASURE THAT MUST BE TRADED OFF AGAINST THE CONCOMITANT REDUCTION IN MAIN BEAM OVERLAP ,INEAR ARRAYS OF VERTICALLY POLARIZED LOG 
 New Faraday rotation estimators based on polarimetric covariance matrix. IEEE Geosci. Remote Sens. 
 Use only the phase characteristic of the matched filter and replace its amplitude response with a smoothed function in the analog portion of the receiver.  Perform trade- off of required digital filter transient response.  If necessary add a reciprocal ripple inverse filter to further reduce range time side  lobes. 
 It is a compact monopulse  roll- and pitch-stabilized radar with 140° azimuth and 60° elevation scan.27 The Israeli  Elta subsidiary of Israeli Aircraft Industries also developed an airborne tracking radar  using this antenna technology for air-to-air combat and ground weapon delivery.28 A ground- or shipboard-based experimental mirror antenna system concept was  developed with dual-band monopulse capability (3.0 GHz and 9.3 GHz bands). The  objective included high-speed beam movement for high-data-rate 3D surveillance  and multitarget precision tracking.29 Dual-band polarization-twist mirror design was  accomplished with a two-layer mirror grid configuration.30 On-Axis Tracking.  The best radar tracking performance is usually accomplished  when the target is essentially on the radar antenna axis. 
 TO 
 J. B.: "Microwave Ferrites," John Wiley and Sons, New York, 1961.  30. 
 PULSE DOPPLER RADAR  4.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 where CEIL( x) is the smallest integer ≥ x. The instantaneous dynamic range supported  by an A/D converter improves about 6 dB per bit.47 For the example cited in Figure 4.15, where the maximum C/N is 53 dB at a 1000-ft  radar altitude and with a fluctuation margin of 10 dB and thermal noise at 1.414 quanta  (3 dB), the A/D converter requires at least 11 amplitude bits plus a sign bit for a total  of 12 bits to achieve the peak A/D dynamic range of 63 dB. The upper portion of  Figure 4.16 illustrates this case. 
 W. S. Ament, F. 
 On the inside of this ring we cut a number of cavities,  and the electrons pulled out of their course by the mag-  netic field parallel to the axis of the tube commence  travelling across the openings of these cavities in a series  of curved orbits. In this way appropriate charges are  produced on the anode segments, giving rise to sustained  high-frequency oscillations inside the cavities themselves,  To link each cavity with the next the magnetron is  ‘strapped’ with short stubs of wire carefully arranged so  that the potentials from cavity to cavity are in the correct  order. Small holes are bored in the otherwise solid  block of the magnetron’s main construction, and short _  lengths of No. 
 1.16 . This page has been reformatted by Knovel to provide easier navigation. vi     Contents   C Band (4.0 to 8.0 GHz)  .................................... 
 TO 
 E., and J. A. Ziegler: MTI Improvement Factors for Weighted DFTs, IEEE Trans., vol. 
 Microwave Power Module (MPM ).23,24 A novel variant of the linear-beam tube is  the microwave power module,  which is an amplifier that employs a solid-state micro - wave integrated-circuit amplifier to drive a moderate-power helix traveling wave tube,  along with an integrated circuit power conditioner, all in a lightweight package. It can  provide high efficiency, wide instantaneous bandwidth, low noise, and average power  levels from several tens to several hundreds of watts. It is said to be smaller and lighter  than comparable TWT and solid-state power sources, and is capable of operating at  high ambient temperatures. 
 BIT !$# 4HIS ARCHITECTURE REALIZES THE ,/ WITH A NUMERICALLY CONTROLLED OSCILLATOR .#/  THAT GENERATES DIGITAL WORDS TO REPRESENT THE COSINE AND NEGATIVE SINE SIGNALS AT THE ,/ FREQUENCY  HERE  -(Z AND SAMPLED AT THE !$# . 
 The main design parameters of a representative HFSWR system—the Daronmont  SECAR radar—are listed in Table 20.4. (The corresponding values for skywave radars  can be found in Table 20.2.) Propagation Considerations in HFSWR Systems.  To a good approximation,  when a target of interest is above the optical horizon of an HFSWR, the field inci - dent on the target can be decomposed into terms that correspond to (i) direct line-of- sight, (ii) sea-surface reflection, and (iii) a lateral or “surface-attached” wave. 
 Gunn and T. W. R. 
 1  Learning Objectives  ................................ ................................ ................................ 
 M. Weiner, “Multistatic radar phenomenology terrain & sea scatter,” RADC-TR-81-75,  vol. 1, May 1981, now unlimited distribution. 
 For the VHS airborne SAR, the DPEC is more challenging because of its complex spatially-variant characteristics. Traditionally, the DPE can be implemented by the multiple aperture mapdrift (MAM) via the azimuth multi-view processing. The basic MAM method (as shown in Figure 2a) [22,23] assumes that the Doppler parameters do not change with respect to target positions. 
 46. Frush, C.: Doppler Signal Processing Using IF Limiting, Preprints, 20th Conf. Radar MeteoroL, pp. 
 10. W. A. 
 WAY ROUND 
  AND LATE 
 125.Davis.P.,andA.Cohen: RigidRadome DesignConsiderations, Elec/rollics, vol.32,no.16,pp,66, fiR69.Apr.17.1959. 126.Hastings, K.N..andJ.(j.Chaplin: DrivesforStecrable Antennas. Hydraulics versusElcctro­ Mcchanics, "DesignandConstruction ofLargeSteera.ble Aerials," lEE(London) Conferellce Puhli­ ca/imlIlO. 
 55. Chuang, C. W., and D. 
 MOVING TARGET DETECTION -EDIUM DETECTION RANGE ACCURATE RANGE  VELOCITY DATA -ISSILE SEEKER 3HORT DETECTION RANGE ACCURATE VELOCITY AND ANGLE RATE DATA MAY NOT NEED TRUE RANGE INFORMATION 3URFACE 
 64. Hansen, V. G.: Performance of the Analog Moving Window Detector, IEEE Trans., vol. 
 (Plessey Co., Ilford, England.)  42. Watanabe. M., T. 
 POWER  LOW 
  # PER KILOMETER 4HE )NTERNATIONAL #OMMISSION FOR !IR .AVIGATION )#!.  USES THE  .!#!  STANDARD ATMOSPHERE  WITH MINOR MODIFICATIONS  PRIMARILY IN THE VALUE OF GRAVITY AND  THE TEMPERATURE OF THE ISOTHERMAL REGION &OR GENERIC RADAR STUDIES AND OTHER RADAR APPLICATIONS  SUCH AS TARGET HEIGHT CALCULATIONS FOR HEIGHT 
 111. Wind Forces on Structures, ASCE Trans., vol. 126, pt. 
 = maximum radar range, 111  (i = antenna gain  A = antenna aperture, m2  l'a = antenna efficiency  11 = number of hits integrated  E;(11) = integration efficiency (less than unity)  L, = system losses (greater than unity) not included in other parameters  rr = radar cross section of target, m2  F" = noise figure  k = Boltzmann's constant= 1.38 x 10-23 J/deg  T0 = standard temperature= 290 K  B = receiver bandwidth, Hz  r = pulse width. s  .f,, = pulse repetition frequency, Hz  (SI N)1 = signal-to-noise ratio required at receiver output (based on single-hit  detection)  This equation can also he written in terms of energy rather than power. The energy in the  transmitted pulse is E, = f'a,/1~ = P1 r and the signal-to-noise power ratio (S/N) 1 can be  replaced hy the signal-to-noise energy ratio (E/ N 0)1, where E = S/r is the energy in the  received signal. 
 (5)wegetGJ(R:) 2=G(l.~)/R~O.~). The same line ofargument followed through with theradar equation gives P-J(R:) 4=G2(]~~)/R&~), which gives the same value ofR,(,ok) when R:isthesame. Inpractice, however, thebroadening ofthebeacon signals islikely tobegreater since i~iscustomary and usually desirable tosetthe sensitivity ofthe beacon receiver sothat the maximum free- space range isconsiderably greater than the radar range toanaverage target. 
 DUCE A SET OF SECONDARY BEAMS AT DISTINCT ANGLES 4HE ADDITIONAL FEEDS MUST BE OFFSET FROM THE FOCUS  AND THE RESULTANT SECONDARY BEAMS WILL SUFFER SOME GAIN LOSS AND DIS 
 1974.  54. Gray, T.: Airborne Doppler Navigation Techniques, chap. 
 The line of siglit  is tlic straiglit-titie dist,ince betweeti radar and target that is just tangent to the surface of tlie  earth. The distarice between radar and target along the line of sight is  ri,, = J~k~lh, t JZ& (12.14)  wliere 11,. 11, = lieiglits of radar antenna and target, respectively  tr = eartli's radius  k = factor discussed in Sec. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.46  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 Depth of First Null in Velocity Response.  When selecting system parameters,  it is useful to know the depth of the first few nulls to be expected in the velocity  response curve. 
 19.10  Inverse Receiver  ................................................  19.12 Angle Tracking: Conical Sc an to Monopulse   ......  19.14  Pulse Doppler (PD) Operation  ............................ 
 NAL AMPLITUDE TO THE LARGEST SPURIOUS SIGNAL AMPLITUDE AND IS USUALLY STATED IN D" 3IMILAR TO 3.2  THE SPURIOUS PERFORMANCE OF AN !$ CONVERTER IS DEPENDENT ON THE &)'52%  )& SAMPLING IN SECOND .YQUIST REGION  
 17”2) controlling theswitch (V,.and Vlb, Fig. 17”2) ahead ofthe decoder. When this switch is 1SeeVol.20ofthisseries fordetails ofthe comparison circuit and motor drive.. 
 [ CrossRef ] 198. Sensors 2019 ,19, 2161 27. Carrano, C.S.; Groves, K.M.; Caton, R.G. 
 Different models are applied depending on the choice of feed used  in the design; examples include waveguide feed horns, microstrip patches, dipoles,  etc. Sometimes the feed model will instead employ measured feed patterns if such  data is available. All models must be normalized to some prescribed radiated power  level, e.g., 1 watt. 
 S.: Digital Signal Processing, chap. 35 of" Radar Handbook," M. I. 
 Real SAR Raw Data-Focusing The SVD decomposition was then applied as a test of the proposed approach to several ERS raw data matrices without any knowledge of the mission ancillary data. The thresholding applied on the range reference function estimated a length of the range chirp of 704 samples. In Figure 8, the focused ERS image obtained with the proposed algorithm (B-SAR) and the focusing obtained by a standard Range Doppler SAR processor are compared. 
 A.: The Influence of Atmospheric Conditions on Radar Performance, J. Inst. Navigation  (London), vol. 
 DELAY CANCELER TRACKING THE PRIMARY SPECTRA AND A  SINGLE 
 GUIDES OR HORNS LOADED WITH DIELECTRIC  THE VELOCITY WILL DECREASE SLIGHTLY &URTHER  IF THE DIELECTRIC PROTRUDES FROM THE RADIATORS OR IF A DIELECTRIC SHEET IS USED IN FRONT OF THE ARRAY  THE VELOCITY OF THE SURFACE WAVE MAY DECREASE DRAMATICALLY 4HIS SURFACE WAVE IS IMPORTANT BECAUSE IT CAN CAUSE A LARGE REFLECTION AND AN ACCOMPANYING LOSS OF THE BEAM  FOR SOME ANGLES OF SCAN 4HIS CAN BEST BE SEEN BY EXAMINING THE CONDITION OF .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°Óx PHASING FOR WHICH THE COUPLINGS FROM MANY ELEMENTS WILL ADD IN 
 Frequency Synthesis Techniques.  The most common techniques are direct  synthesis, direct digital synthesis, and frequency multiplication. Direct synthesis is  the process of generating frequencies through the multiplication and mixing of a  number of signals at different frequencies to produce the required output frequency. 
 -   2 * 3ULLIVAN   2ADAR &OUNDATIONS FOR )MAGING AND !DVANCED #ONCEPTS  2ALEIGH  .# 3CI4ECH    PREVIOUSLY PUBLISHED AS  -ICROWAVE 2ADAR )MAGING AND !DVANCED #ONCEPTS   .ORWOOD   -! !RTECH (OUSE     , * #UTRONA  h3YNTHETIC APERTURE RADAR v IN - 3KOLNIK   2ADAR (ANDBOOK  ND %D  .EW 9ORK  -C'RAW 
 Appl. Earth Obs. G éoinf. 
 DIGITAL CONVERTER AND DIGITAL COMPONENT TECHNOLOGY HAVE  TRANSFORMED THE RECEIVER FRONT ENDS OF RADAR SYSTEMS  PROVIDING HIGHER PERFORMANCE AT LOWER COST 4HIS SECTION WILL DESCRIBE HOW THESE NEW TECHNOLOGIES ARE BEING APPLIED TO RADAR SYSTEMS AND THE BENEFITS THEY BRING TO SYSTEM PERFORMANCE 3IGNAL 3AMPLING "ASICS  $IGITAL SIGNAL PROCESSORS ARE SAMPLED SIGNAL SYSTEMS  3AMPLING IS THE PROCESS BY WHICH A CONTINUOUS ANALOG  SIGNAL IS MEASURED AT REGULAR INTERVALS OF TIME THE  SAMPLING INTERVAL   PRODUCING A SEQUENCE OF DISCRETE NUMBERS  SAMPLES  THAT REPRESENTS THE VALUES OF THE SIGNAL AT THE SAMPLING INSTANTS 4HE  SAM 
 THE 
 The time delay and doppler shift are expressed in terms of target range and range- rate by td = 2R/c (s) and fd = –(2/l)Vr (Hz), where R is the target range ( m), Vr = dR/dt Signal Spectrum Comments  1 x(t) X(  f  ) Fourier transform pair  2 Ax(t) + Bu(t) AX(  f  ) + BU(  f  ) Linearity  3 x(−t) X(−f  ) Signal time reversal  4 x*(t) X*(−f) Conjugate of signal  5 dx/dt j2πfX(  f  ) Time domain differentiation  6 −j2πtx(t) dX/df Frequency domain differentiation  7 x(t − t  ) X(  f  ) exp ( −j2πft ) Signal time shift  8 x(t)exp( j2πf0t) X(  f − f0 ) Signal frequency shift  9 x(t/T) |T|X(  fT ) Time scaling 10 x t y t( ) ( )∗ X(  f  )Y(  f  ) Time domain convolution 11 x(t)y(t) X f Y f ( ) ( )∗ Time domain multiplication 12repTx t[ ()] | / | [ ( )] 11 T X fT combWoodward’s repetition operator 13combTx t[ ()] | / | [ ( )] 11 T X fTrepWoodward’s comb operator 14 X(t) x(–f  ) Time-frequency interchange (duality) 15 d (t) 1 Delta function in time 16 1 d (  f  ) Delta function in frequency 17 rect(t) sinc(  f  ) rect function in time 18 sinc( t) rect(  f  ) rect function in frequency 19 exp(– πt2) exp(– π f2) Gaussian time functionTABLE   8. 11 Fourier Transform Rules and Pairs ch08.indd   38 12/20/07   12:52:14 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 (From ~uerev,~' Courtesy IEEE.)  116INTRODUCTION TORADAR SYSTEMS Symmetflcal --15 aboLlt v/v8=\4\25 -105 o -35 -40-30--25--5 --20-5 -15 ill-0 -;;;-10 Vlc0 ~-20 Q) a::-25 -30 -35 -402 4 6 Figure4.17Frequency response ofafive-pulse (four-period) stagger.(FromShrader,s COl/rces}J McGraw­ HillBookCo.) constant periodequaltotheaverage periodYav=(TI+T2+...TN)/N,thenthefirstblind speed (11is VInl+n2+...+nN= VB N(4.11) Itisalsopossible toapplyweighting tothereceived pulsesofastaggered prfwaveform. Anexample isshowninFig.4.18.22Thedashedcurveistheresponse ofafive-pulse canceler withfixedprfandwithweightings of~,1,-3!,1,1.Thesolidcurveisforastaggered prfwith o -10 CD-20~ Q) Vl C 0Q. Vl Q)-30a:: -40-I I I, I I I I I 'III , II 1/IIf I \/I I\!,1 It· 1/II ---- Fixedprf --- Staggered prfII \ I I I \ I \ I \ fIJ I/', II \ I\I 1/ "\ I I I \, \ \ I I I I I 4.0 1.0 2.0 3.0 Targetvelocityrelativetofirstblindvelocityatfixedprf-50l-------.i...:----------:::-'=--------:::-'-::------::-'-:o Figure4.18Response ofaweighted five-pulse canceler. 
 With each bit representing about  6 dB of SNR, the minimum number of bits required to represent the filtered signal  could grow from 16 to 17. In an actual application, the system designer needs to analyze the effects of sam - pling and digital processing and determine how many bits need to be carried through  the calculations in order to preserve SNR and prevent overflow. Considerations  include front-end system noise, which is typically allowed to toggle two or more  bits (four or more quantization levels) of the ADC output. 
 The selection of a suitable waveform for transmission, at least in terms of resolu - tion, can be considered a function of the duration of the complex envelope of the sig - nal. The output from most ultrawideband radar systems can be compared in terms of a  time-domain representation of the waveform. Almost all types of radar can be assessed  not just by their signal-to-noise and signal-to-clutter ratios but also by comparing their  inherent range sensitivity. 
 END SENSITIVITY TIME CONTROL 34#  SUPPRESSES SIDELOBE DETECTIONS AT SHORT RANGES AND REDUCES DYNAMIC RANGE REQUIREMENTS-ULTIPLE BLIND SPEEDS 5SUALLY DOES NOT MEASURE RADIAL TARGET VELOCITY 0OOR GROUND 
 Zhang et al. [ 5] showed an application in ship classiﬁcation with transfer learning and ﬁne-tuning. Kang et al. 
 TO 
 CAST BAND  AND AS HIGH AS SEVERAL HUNDRED '(Z MILLIMETER WAVE REGION  -ORE USU 
 8.15 for the two cases d = 0.5A0 and 0.6..1.0• The onset of the grating lobe can set a limit to  the maximum angle of scan. The appearance of grating lobes is not symmetrical about 00 = 0.  If, for example, the element spacing were 0.5...1.0 and 1/d = 15, the beam can be scanned from  00 = 0 to 00 = 62°. 
 5.2). The angle betweerl  tlie axis of rotation (wliicli is usually, but not always, the axis of the antenna refiector)and the  ;~uir; of tlic ;i~itcrit~;~ I~ciitri iq c;illctl 111c scl~~ilit anglc. Cotisidcr 8 targct at positiori A. 
 DIMENSIONAL IMAGE OF A TARGET OR A SCENE   SUCH AS A PORTION OF THE SURFACE OF THE EARTH AND WHAT IS ON IT  4HESE RADARS USUALLY  ARE ON MOVING PLATFORMS 3IDELOOKING AIRBORNE RADAR 3,!2   4HIS AIRBORNE SIDELOOKING IMAGING RADAR PRO 
 Monte Carlo simulation experiments using the benchmark160  have been carried out in order to assess the benefits of the above described ECCMs.  More specifically, the adaptation of the detection threshold has been used as A-SOJ  whereas the technique based on discarding the measurements with higher range has  been adopted as A-RGPO. Three types of targets (numbered 1, 5, and 6) have been  considered: target 1 represents a cargo aircraft while targets 5 and 6 represent fighter/ attack aircrafts with a much higher degree of maneuverability. 
 PLEX TO BE DESCRIBED ADEQUATELY IN ANY OF THE MODELS  AND THE EFFECTS OF SIGNALS THAT PEN 
 Triode and  tetrode grid-controlled tubes may be modulated by applying a low-power pulse to the grid.  Plate modulation is also used when the radar application cannot tolerate the interpulse noise  that results from those few electrons that escape the cutoff action of the grid.  The basic elements of one type of radar modulator are shown in Fig. 
 PURPOSE COMPUTERS COMBINED WITH SPECIAL SIGNAL PROCESSING COMPONENTS USING $IGITAL 3IGNAL 0ROCESSING $30  CHIPS OR FIELD PROGRAMMABLE GATE ARRAY &0'!  DEVICES #ONTINUED TECHNOLOGY ADVANCES WILL PERMIT ADVANCED  BUT MATURE  SIGNAL PROCESSING ALGO 
 2.13  Bandwidth and Matching  Factors  .......................  2.14 . This page has been reformatted by Knovel to provide easier navigation. 
 263–266, June 1986. 28. E. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar.  PULSE COMPRESSION RADAR  8.376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 Radar Transmit Waveforms .2,68,71 –73 The transmitted waveforms used in radar  are bandpass signals that can be expressed in the form  x t a t f t t ( ) ( )cos[ ( )] = + 20π φ  (8.38) where a(t) is the amplitude modulation ( V), f(t) is the phase modulation (rad), and  f0 is the carrier frequency (Hz). 
 ADDED 
 73-75, January 1968. 9. Skolnik, M. 
 Increasing the CRT diameter does not  necessarily help, since the spot diameter varies linearly with the screen diameter. Another  limitation is the dynamic range, or contrast ratio, of an intensity modulated display which is of  the order of 10 dB. This might cause blooming of the display by large targets so as to mask the  blips from nearby smaller targets. 
 SENSING  GATES EITHER TO LEAD OR LAG THE CENTER OF THE TARGET 4HIS PROVIDES SOME REJECTION BY THE GATES OF UNDESIRED RETURNS THAT MIGHT OCCUR NEAR THE TARGET  SUCH AS THE ECHOES FROM  OTHER NEARBY TARGETS 4HRESHOLD DEVICES ARE ALSO USED AS LEADING 
 Thestalo.coho.andthemixerin whichtheyarccombined plusanylow-level amplification arecalledthereceiver-exci(cr be­ causcofthedualroletheyserveinhoththereceiver andthetransmitter. Thecharacteristic featureofcoherent MTIradaristhatthetransmitted signalmustbe coherent (inphase)withthereference signalinthereceiver. Thisisaccomplished intheradar systemdiagramed inFig.4.5bygenerating thetransmitted signalfromthecohoreference signal.Thefunction ofthestaloistoprovide thenecessary frequency translation fromtheIF tothelransmitted (RF)frequency. 
 For example, with two tar - gets present at different dopplers, the two frequencies observed during the FM period  cannot be unambiguously paired with the two frequencies observed during the no-FM  period. To mitigate this problem, a three-segment scheme is used with the following  segments: no-FM, FM-up, and FM-down. The range is found by selecting returns from  each of the three segments that satisfy the relations  f f f1 0 2 < <  (4.12)  f f f1 2 02 + =  (4.13) ch04.indd   34 12/20/07   4:53:20 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 87.Gent.H..I.M.Hunter. andN.P.Robinson: Polarization ofRadarEchoes. Including Aircrart. 
 provided that the latter is small compared to the wavelength.  It indicates that therms phase variation about the mean phase plane must be less than l/14 for  a one dB loss of gain. For shallow reflectors, the two-way path of propagation means that the  surface error must be one-half this amount, or J/28. 
 The blanked-out sectors abeam aredue toshadows cast bytheengine nacelles oftheC-47 aircraft inwhich the setwas installed. Figure 15.12 was taken while aspecial experimental antenna of30-in. horizontal aperture was inusc; thus the azimuth resolution and range pcrformante arebetter than those attained with thestandard 18-in. 
 AVG   AVERAGE TRANSMITTED POWER   '   ANTENNA GAIN   R   TARGET RADAR CROSS  SECTION 2#3    !   ANTENNA APERTURE AREA   G   ANTENNA EFFICIENCY  AND THE RADAR LOSSES  ARE REPRESENTED BY ,OSS  &OR 3!2  AT PSQ     FROM %Q     T2 6! L DCR    4HUS  3.2,OSS4X 
 Microwave  Symp. , vol. ‘79CH1439-9 MTT-S’, 1979. 
 LOAD DISPLACEMENT OF  THE VESSEL IN KILOTONS  4HE RELATIONSHIP IS BASED ON MEASUREMENTS OF SEVERAL SHIPS  AT LOW GRAZING ANGLES AND REPRESENTS THE AVERAGE OF THE MEDIAN 2#3 IN THE PORT AND  STARBOARD BOW AND QUARTER ASPECTS  BUT EXCLUDING THE BROADSIDE PEAKS 4HE STATISTICS INCLUDE DATA COLLECTED AT NOMINAL WAVELENGTHS OF     AND  CM FOR SHIP DIS 
 McKay, “A digital beamforming processor,” Real Time Signal   Processing III, SPIE Proc ., vol. 241, pp. 232–237, 1980. 
 A. Mueller: Radar Back-scattering Cross Sections for Nonspherical Targets.  lRE Trans., vol. 
 The term "reflection  coeffic~ent " as usually found in the literature is generally that of the coherent component. The  incoherent, or fluctuating, component of a surface-scattered signal is characterized by a  random phase and amplitude. The incoherent component of the forward-scattered signal from  a roirgh surface behaves differently from the coherent component as a function of roughness. 
 DOWNWIND RATIO OF RADAR RETURN CALCULATED FROM FACET SIZE STATISTICS OF  WIND DISTURBED WATER SURFACE v 0ROC )2%  VOL   PP n    $ / -UHLEMAN  h2ADAR SCATTERING FROM VENUS AND THE MOON v  !STRON *  VOL   PP n     ! + &UNG  h4HEORY OF CROSS POLARIZED POWER RETURNED FROM A RANDOM SURFACE v  !PPL 3CI 2ES   VOL   PP n    ) +ATZ AND , - 3PETNER  h4WO STATISTICAL MODELS FOR RADAR RETURN v  )2% 4RANS  VOL !0 
 DITIONS EXIST AND WHAT THESE CONDITIONS ARE DETERMINES THE NAME AND NATURE OF THE DUCT 3URFACE $UCTS  )F THE METEOROLOGICAL CONDITIONS CAUSE  A TRAPPING LAYER TO OCCUR   SUCH THAT THE BASE OF THE RESULTANT DUCT IS AT THE %ARTHS SURFACE  A SURFACE DUCT IS  FORMED 4HERE ARE THREE TYPES OF SURFACE DUCTS BASED ON THE TRAPPING LAYERS RELATION 
 W.: Notes on Duct Influences on Line-of-Sight Propagation, IEEE Trans.,  vol. AP-22, pp. 295-302, March, 1974. 
 148  13.3.5 Processing ............................................................................................................. 149  13.3.6 Reflection Cross- Section in Street Traffic at 76 GHz ........................................... 149  13.3.7 Power Budget ........................................................................................................ 
 pp. 297-305, March, 1955.  62. 
 R. G. Hajovsky, A. 
 RADIO BASED BISTATIC RADAR v PRESENTED AT !/# TH -ULTINATIONAL 0#2  #ONFERENCE  3YRACUSE  .9  /CTOBER     4 ! 3OAME AND $ - 'OULD  h$ESCRIPTION OF AN EXPERIMENT AL BISTATIC RADAR SYSTEM v IN  )%%  )NT 2ADAR #ONF 0UBL     PP n  % (ANLE  h0ULSE CHASING WITH BISTATIC RADAR 
 Arlington. Va.. Apr. 
 Appl. Phss., vol. 25, pp. 
 The baseband in-phase ( I) and quadrature-phase ( Q) signals  are digitized using a pair of A/D converters providing a representation of the IF signal,  including phase and amplitude without loss of information. The resulting digital data can  then be processed using a wide variety of digital signal-processing algorithms, depend - ing on the type of radar and mode of operation. Processing such as pulse compression,  doppler processing, and monopulse comparison, all require amplitude and phase infor - mation. 
 The filter section isinstalled toprevent radiation ofharmonics and other spurious c.ff-frequency signals. Ithasbeen designed tohave 50ohms impedance,. SEC. 
 The latter antenna system’ has the following advantages over the linear array: 1Similm antennas aredescribed inChap, 14,Vol. 12ofthisssries,. SEC. 
 There is no theoretical model of target scattering that leads to  the Jog-normal distribution, although it has been suggested that echoes from some satellite  bodies, ships, cylinders, plates, and arrays can be approximated by a log-normal probability  <l istribution. 42·4]  Figure 2.25 is a comparison of the several distribution models for a false alarm number of  l06 when all pulses during a scan are perfectly correlated but with pulses in successive scans  independent (scan-to-scan fluctuation).  The fluctuation models considered in this section assume either complete correlation  'between pulses in any particular scan but with scan-to-scan independence (slow fluctuations),  -.. 
 For example, if t  =  1 microsecond, B(pulse ) = 1 MHz. This is far less than the bandwidth of the overall  step-frequency waveform, equal to the difference between the frequencies of the last  and first pulses in the sequence, which is typically hundreds of MHz.) Step-frequency pulse compression has not proven successful in airborne or space - borne applications, as compared to the linear-FM (LFM) waveform (see Section 2.6  of Carrara3), and is seldom used. Linear-FM (LFM) is a common waveform used in  operational high-power radars, because (1) each pulse contains the full bandwidth,  thereby enabling the full bandwidth to be transmitted and received much more  quickly than with step-frequency—a great advantage when the radar is moving,  such as for SAR—and (2) the hardware is relatively inexpensive and mature. 
 LIMITED ANNULI ALL HAVE AREAS EQUAL TO THAT OF THE INITIAL PULSE 
 (9) and (10) Inner and outer  marker radio beacons. (12) Very-high-frequency communt-  cation with other aircraft. (13) Medium~-frequency direction-  finding stations. 
 W.: Frequency-scanned Arrays, chap. 13 of " Radar Handbook," M. I. 
 This condition, inourideal system ofFig. 2.3, leads to (21) Aquestion offundamental interest, though not asyet ofmuch practical moment, isthe one raised eaiiier about thetemperature tobe assigned tothe antenna radiation resistance. This iscertainly notin general the temperature ofthemetal parts ofthe,antenna. 
 TheradarcrosssectionaoftargetsatHFisoftendifferent thanatmicrowaves. Since manytargetshavedimensions comparable totheHFwavelength, orcomponent structures withdimensions comparable tothewavelength, thetargetisoftenintheresonance region wheretheradarcrosssections aregenerally largerthanatmicrowaves. AtthelowerHF frequencies wherethewavelength islargecompared tothetargetdimensions, thecrosssection willbeintheRayleigh regionwhereadecreases rapidlywithdecreasing frequency. 
 Free-space radar performance is modified by,scattrr.ir~y  of electrotnagnetic energy from the surface of the earth,-htiort caused by an inhomo-  pcneous at~~lospllere, and ~,~rer~~g~iorr by the gases constituting the atmosphere. Also included  under the subject of propagation is the e.~ter.rlc~l rroise environment in which the radar finds  itself. ?'lie radar is also affected by tlic r.q//ectioir. 
 35. Bogle, R. W., and D. 
 By pairs 1 and 2, the time function includes the superposition of 2(n — 1) echoes that occur in n — 1 symmetrical pairs. If the coefficients Fm are selected to specify the Taylor weighting function39'42'43 WTay(/), the corresponding resultant time function wTay(0 exhib- its good resolution characteristics by the criterion of small main-lobe width for a specified sidelobe level. Taylor coefficients chosen for a -40 dB sidelobe level, with n selected as 6, lead to the main-sidelobe structure indicated by curve C of Fig. 
 24.36  24.12 Ground-Wave Radar Pe rformance  .........................  24.38  25. Bistatic Radar   .......................................................... 
 W. W. Salisbury, “Absorbent Body for Electromagnetic Waves,” U.S. 
    
 Mostcommercial marineshipboard radarsusedfornavigation employ suchamount.Theelevation beamwidth ismadebroadenough (typically 20°)sothatthe surfaceofthesearemains illuminated duringtherolloftheship.Acorrection canbeapplied totheindicator (datastabilization) toaccount fortheerror. Thetwo-axis mountofFig.7.3th.sometimes calledanaz-elmount,enablesthebeamto bemaintained atthehorizontal oratanyangleaboveorbelowthehorizon (line-of-sight stabilization). Thebeamcanbedirected toanypointbythepropercombination ofazimuth (train)andelevation angles.Fortargetsoverhead, theangularaccelerations required arequite high.Itisnotpractical tousesuchamount,therefore, fortracking targetsthrough thezenith, asinthetracking ofsatellites. 
 June. 1954.  31. 
 54. E. Aronoff and D. 
 Two versions of the control and data-handling part of an FM-CW scatterometer are shown in Figs. 12.21 and 12.22. Figure 12.21 shows the common range-tracking scatterometer. 
 It can be clearly seen that the azimuth sidelobe asymmetry exists in the IMAM result, while for the EMAM result, the main-lobe is narrower 63. Sensors 2019 ,19, 213 and the side-lobe is lower and basically symmetrical, which explains that the EMAM method is better than the IMAM method.    (a) (b)   (c) (d)  Figure 11. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 25.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 these systems in a radar application is reset time. 
 POL FEED  A  PHOTO OF SYSTEM  B   MECHANICAL #!$ RENDERING SHOWING PANELIZED REFLECTOR SURFACE AND SUPPORT STRUCTURE AND  C  DUAL 
 BEAM DOPPLER SYSTEMS CAN ACCURATELY  MEASURE HORIZONTAL WINDS IN ALL THREE VELOCITY COMPONENTS IF THE WIND IS UNIFORM &OUR 
 BEAM CLUTTER  ENHANCE TARGET DETECTION  AND AID  IN TARGET DISCRIMINATION OR CLASSIFICATION -4) RADARS CAN ALSO BE IMPLEMENTED USING A DOPPLER FILTER BANK  BLURRING THE HISTORIC DELINEATION BETWEEN -4) AND PULSE DOPPLER RADARS !S A RESULT  THIS BOOK WILL DEFINE -4) RADARS AS THOSE RADARS WHOSE 02& IS SUFFICIENTLY LOW ENOUGH TO PROVIDE AN UNAM 
 Atlas, “Simultaneous ocean cross-section and rainfall measurements from  space with a nadir-looking radar,” J. Atmos. Ocean. 
 In the ocean application, relatively small changes in radar backscatter may cor - respond to substantial differences in the retrieved wind information.§120,121 It follows  that the dominant requirement for this class of radar is the accuracy and precision   of the received power measurement.* However, the next step, vector wind retrievals—   transforming the radar backscattered power into accurate estimates of wind speed  and direction—is far from trivial. Indeed, the technique fails for the very low  wind speeds that do not generate wavelength-scale surface roughness. In the limit,  FIGURE 18.17  The hybrid-polarity SAR architecture first used by the Mini-RF lunar radars on  Chandrayaan-1  and LRO Transmitter & waveform H Receive V Receive90° HTiming and control Antenna VH|H| |V|HV* H V *XH Processor V Processo rV §  http://www.eumetsat.int/groups/ops/documents/document/pdf_tm03_rev-scatterometer-w.pdf *  Note that both accuracy and precision are required. 
 STATE RADARS USUALLY REQUIRE 4HE SOLID 
 AROUND CLUTTER IS CANCELED IN A POWER AMPLIFIER -4)  SYSTEM 4HE TRANSMIT 
 Assumptions  made in deriving Figure 6.23 are 1. Returns on the two frequencies are added in voltage or power prior to the detection  decision rather than being subjected to individual detection decisions. 2. 
 4.2 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 Time gating allows the blanking of direct transmitter leakage into the receiver. This  permits the use of a single antenna for transmit and receive, which otherwise would  not be feasible for CW radar due to excessive transmit/receive isolation requirements.  Pulsed radars can also use range gating, a specific form of time gating, which divides  the interpulse period into cells or range gates . 
 Ideally, STCshouldmaketheaverageclutterpoweralwaysequaltothenoisepower.Thusitsrange variation shouldbeidentical totheclutter-power rangevariation. Ithasbeensuggested that STCforacivil-marine radarhaveagainproportional toR-3outtoarangeof8hahw/3A,after whichitisproportional toR-',whereR=range,ha=radarantenna height,hw=wave heightfrompeaktotrough,andA.=radarwavelength.34STCmaybeimplemented intheIF ofthereceiver, butitcanalsobeincorporated atRFbyinserting variable-attenuation micro­ wavediodesaheadofthereceiver. Aparticular STCcharacteristic canbelimitedbychanges in clutterduetochanges inambient conditions (suchaswindspeedanddirection, orbyanoma­ louspropagation), andbythenonuniformity ofclutterwithazimuth. 
 Swerling, P.: Detection of Fluctuating Pulsed Signals in the Presence of Noise, IRE Trans., vol. IT-3,  pp. 175-178, September, 1957. 
 H. Yocom, “High power traveling wave tubes: Their characteristics and some applications,”  Microwave J ., vol. 8, pp. 
 ª«¬¹º»c¯  WHERE )O   IS THE MODIFIED "ESSEL FUNCTION OF ORDER . 
 AES-7, pp. 269–278,  March 1971. 58. 
 ch16.indd   63 12/19/07   4:56:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 Digital Processing of Synthetic Aperture Radar Data: Algorithms and Implementation ; Artech House: Norwood, MA, USA, 2005; p. 625. ©2019 by the authors. 
 The two-channel monopulse technique is used in the AN/ SPG-55 tracking radar and the AN/FPQ-10 missile-range instrumentation radar. The modulation caused by the microwave resolver is of concern in instrumenta- tion radar applications because it adds spectral components in the signal which complicate the possible addition of pulse doppler tracking capability to the radar. This system provides instantaneous AGC operation with only two IF channels and operation with reduced performance in case of failure of either channel. 
 and Mazda have  produced very efficient microwave diodes as mixers,  much radar equipment at present in use has a crystal-  mixer capsule; and the mixer, whether it be crystal or  diode, is inserted usually in the concentric transmission  line itself.  The capsule is mounted in a high-impedance section  of the transmitter line, and into the same compartment  are fed the ‘pipes’ bringing in the e.m.f. from the  klystron local oscillator, and also those leading to the  first IF stage of the centimetric superhet. 
 However, because the echo from a weak target  combined with noise may not always cross the threshold, a limit may be set, such as  15 crossings, that must occur during the integration period for a decision that a target is  present. For example, performance on a non-scintillating target has a 90% probability  of detection at a 2.5 dB-per-pulse SNR and a false alarm probability of 10–5. The AN/ FPS-16 and AN/FPQ-6 instrumentation radars use these detection parameters with 10  contiguous range gates of 1000 yd each for acquisition. 
 Thereareseveralinteresting factsillustrated byFig.2.7.Atfirstglance,itmightseemthat thesignal-to-noise ratiorequired fordetection ishigherthanthatdictatedbyintuition, even foraprobability ofdetection of0.50.Onemightbeinclinedtosaythatsolongasthesignalis greaterthannoise,detection shouldbeaccomplished. Suchreasoning maynotbecorrectwhen thefalse-alarm probability isproperly takenintoaccount. Another interesting effecttobe notedfromFig.2.7isthatachangeofonly3.4dBcanmeanthedifference betweenreliable detection (0.999)andmarginal detection (0.50).(Whenthetargetcrosssectionfluctuates, the. 
 722 RADAR RELAY [SEC. 17.13 relay links isa100-Mc/sec frequency-modulated system. The equip- ment operates atfour frequencies between 78and 116 Me/see, channel- changing being accomplished inthereceiver byacoil-switching mechanism and inthe transmitter byplug-in coils. 
 Af TI iir~pr.ovenrertt factor. The signal-to-clutter ratio at the output of the MTI system divided  by the signal-to-clutter ratio at the input, averaged uniformly over all target radial veloci:  ties of interest.  Srrhclrrtt~r visibility. 
 Depending on the receiver configuration and the choice of IF frequencies, the cross modulation could cause serious errors and allow vulnerability to jamming. Reference 21 describes how the sum- and difference-channel bands in the wideband IF can be arranged to minimize cross coupling and suggests use of narrow banding to separate each signal before lim- iting in order to reduce jamming effects. A two-channel monopulse receiver22 may also be used by combining the sum and difference signals at RF, as shown in Fig. 
 I. Marcum, “A statistical theory of target detection by pulsed radar,” IRE Trans ., vol. IT-6,   pp. 
 324 1NTRODUC.TION TO RADAR SYSTEMS  In each of these, the proper radar waveform must be selected along with the corresponding  receiver processing. This is known as radar sigual ,rta,tugenlent and is an important function of  the computer. In the AN/FPS-85 satellite-surveillance radar, for example, seven different radar  waveforms were available for performing the target detection and tracking mission as sl~own  in Table 8.1 .' '%n eighth waveform was used for alignment of the transmitter and recelver  mod 11 les. 
 (/?) Simpli- fied perspective.COUPLING SLOTVANE RESONATORCAVITY MODEATTENUATOR TE0nSTABILIZING CAVITY RFOUTPUT OUTPUT VACUUMWINDOWVACUUM BELLOWSINNER CIRCUIT MODEATTENUATORCATHODE TUNING. PISTONCAVITYANODEVANES CATHODESURFACE (a) OUTPUT COUPLINGFROM END OF CAVITY MAGNETICFIELDBCATHODE ANODE VANES COUPLING SCOTS(b)HAL'F-WAVELENGTHCAVITY . 1. 
 IEE. vol. I lO. 
 Tile additional degrees of freedom available in the design of recursive delay-line filters  offer a steady-state response that is superior to that of comparable nonrecursive filters. How-  ever ttie feedback loops in the recursive filter result in a poor transient response. The presence  Angular frequency, w  (a)  :::I ,  Figure 4.14 (a) Three-pole Chebyshev low-pass filter  OO 1/T characteristic with 0.5 dB ripple in the passband; (b-d)  Frequency delay-line filter ,:haracteristics derived from (a). 
 If more than one target is present, the echo signal  becomes 9omplicated and the meaning of the phase measurement is doubtful. The theoretical  accuracy with which range can be measured with the two-frequency CW radar can be found . CW AND FREQUENCY-MODULATED RADAR 97  from the methods described in Sec. 
 These probabilities must be known beforehand in the  Ideal Observer.  The false-alarm probability depends upon the miss probability in the case of the Ideal  Observer. This is unlike the Neyman-Pearson Observer in which Pra was fixed. 
 The SIN over an isorange contour, (SIN)1 is 4k(l + cos P)2 (S/N)i = [(Rr + K*)2 -L2]2 (25.6) where the denominator defines the isorange countour and the bistatic angle P de- fines the target's position on the isorange contour. The maximum bistatic angle, pmax, on an isorange contour is 2sin~l [LI(R7* + RK)], where L/(RT + RR) is the eccentricity of the isorange contour. The minimum bistatic angle, pmin, is zero for all isorange contours. 
 The far-field criterion often requires that the range to  the target be several thousand feet (see Figure 14.20). Because the typical target height  above the ground is a few dozen feet at best, the elevation angle to the target as seen  from the radar is 1° at most and often less. At such low grazing angles, the ground is  strongly illuminated by the antennas, and unless the ground bounce can be suppressed,  the target will be illuminated by a multipath field. 
 List of simulation parameters. Parameters V alue Parameters V alue Aircraft Height 20 km Bandwidth 80 MHz Incidence Angle 30◦Sample Rate 100 MHz Wavelength 0.03 m PRF 70 Hz Velocity 100 m /s Antenna Length 4.0 m Flight Angle 2◦Pulse Duration 10 Baseline 12 m Flight passes 31 5.1. Point T arget Simulations Simulations for a point target were ﬁrst performed to test the proposed method, as shown in Figure 5. 
 $  RADAR v )%%% 4RANS  VOL !%3 
 REFLECTOR ANTENNAS  12.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 The final step in the PO-based pattern solution is to calculate the reflector far fields  via a vector integration of the product of the surface current and the free space Green’s  function.44 The magnetic vector potential A is defined by the equation  AJ e dr r rjkr r =′ −′ ∫∫∫− − ′| | | |4π (12.36) The vector E-and H-fields are related to Avia simple derivatives and/or vector   multiplications. In practice, Eq. 12.36 is computed as a summation of numerical inte - grations. 
 When measuring G1 and G2, the array must be dis- placed for the second measurement to ensure that each subarray is in the same physical position on the antenna range. Electronically Displaced Phase Center Antenna. Figure 16.1 Ia shows the pulse-to-pulse phase advance of an elemental scatterer as seen by the radar receiver. 
 LAW DETECTED RETURNS "Y THE MID 
 Greenwald, R. A., K. B. 
 SQUARED PATTERN AND  B  FREE 
 DIGITAL #ONVERSION  !NALOG 
 ENERGY DISTRIBUTIONS FOR THE THREE VIEWS OF THE 3." AIRCRAFT  A  NOSE VIEW   B  SIDE VIEW  C  TAIL VIEW  AND D  SIDE VIEW OF TWO SMALL TWO 
 More and more functions that historically were implemented in analog  hardware are now being performed digitally, resulting in increased performance and  flexibility and reduced size and cost. Advances in analog-to-digital converter (ADC)  and digital-to-analog converter (DAC) technologies are pushing the border between  analog and digital processing closer and closer to the antenna. For example, Figure 25.1 shows a simplified block diagram of the receiver front  end of a typical radar system that would have been designed around 1990. 
 CFAs.4'16-18 The high-gain CFA19 was not developed until 1987, but it is very attractive, both because it requires less drive power and because the presence of RF drive at the cathode results in lower noise levels. Backward-wave CFAs were developed first and were applied first (the amplitron).15 In backward-wave devices, the voltage required for a given peak current is essentially proportional to frequency, but this can be accommo- dated by the inherent contant-power characteristic of a line-type modulator or by a hard-tube modulator operated in the constant-current region. The constant-current switch tube also helps to regulate CFA current against HVPS capacitor-bank-voltage droop. 
 (ILL "OOK #OMPANY     CHAP   * 0 $ONOHUE AND & - )NGELS  h!MBIGUITY FUNCTION PROPERTIES OF FREQUENCY HOPPED RADARSONAR  SIGNALS v 0ROC OF THE  3OUTHEASTCON  SESSION "  PP n   * 0 #OSTAS  h! STUDY OF A CLASS OF DETECTION WAVEFORMS HA VING NEARLY IDEAL RANGE 
 PRODUCING WAVES  YET THE IMPORTANCE OF THESE EFFECTS WERE UNAPPRECIATED OVER MOST OF THE HISTORY OF SEA CLUTTER MEASUREMENTS  SO AIR AND SEA TEMPERATURES WERE SELDOM RECORDED &INALLY  EVEN IF THE IMPORTANCE OF AN ENVIRONMENTAL PARAMETER HAS BEEN RECOGNIZED  IT IS OFTEN DIFFICULT OR TOO EXPENSIVE  TO ME ASURE IT ACCURATELY IN THE  FIELD UNDER REAL SEA CONDITIONS 7HILE MANY ASPECTS OF SEA CLUTTER THUS REMAINED FRUSTRATINGLY ILL 
 19–40. 83. N. 
 Therefore we may write&, =h2 =h .  The receiver separates the two components of the echo signal and heterodynes each  received signal component with the corresponding transmitted waveform and extracts the two  doppler-frequency components given below:  vl~ = sin (+Ztrfdt - ----  C 4nf1 Ro)  The phase difference between these two components is  Hence  which is the same as that of Eq. (3.17), with Af substituted in place of.fo. 
 The gyroscopes used inshipborne antenna stabilization areaccurate towithin 2’to7’;theerror seems tobeafunction oftheroll, pitch, and heading ofthe vessel. The large synchros used inthis work areliable toerrbyabout 10’to30’. Itfollows that agood shipborne equipment, using synchros geared ashigh as36to1forincreased accuracy, holds the beam with anaverage error ofaslittle as5’,although momentary errors ofmore than twice this magnitude may alise. 
 J. J.. T. 
 In this section, PolSAR TEC derived with magnetic ﬁeld at 400 km is used, which is 11.4 TECU. Still, to account for potential residual calibration errors, only pixels of SNR > 10 dB are employed. For clarity, the TECs of “Poker Flat ISR” and “Poker Flat ISR (average)” are also given here, which are 12.37 TECU and 12.23 TECU, respectively. 
 Afifi, “Preliminary results on the deter - mination of the sources of scattering from vegetation canopies at 10 GHz,” pts. I and II, Int. J. 
 ENCES IN R   FOR DIFFERENT PARTS OF THE GROUND PRODUCE IMAGE 
 OFF "ECAUSE THE PINCH 
 Any use is subject to the Terms of Use as given at the website. Sea Clutter. 15.6  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 The rms waveheight contains contributions from all the waves on the surface, but  very often it is the peak-to-trough height for the higher waves that is of major interest.  This is certainly the case for a ship in a seaway or in the shadowing of the surface at low  radar grazing angles. 
 The (+ ) indicates 0 phase and (- ) indicates x radians phase.  The autocorrelation function, or output of the matched filter, is shown in (h). There are six  equal time-sidelobes to either side of the peak, each at a level - 22.3 dB below the peak. 
 The unscented Kalman Filter  approximates the covariance matrix with a set of 2 L + 1 sample points, where L is the  number of state dimensions. The sample points are propagated through an arbitrary  transform function and then used to reconstruct a gaussian covariance matrix. This  technique has the advantage of representing the covariance accurately to the third  order of a Taylor series expansion. 
 Some  of the nomenclature employed to designate the various frequency regions is also shown.  Early in the development of radar, a letter code such as S, X, L, etc., was employed to  desigr~ate radar frequency bands. Although its original purpose was to guard military secrecy,  the designations were maintained, probably out of habit as well as the need for some conven-  ient short nomenclature. 
 Trunk and J. D. Wilson, “Association of DF bearing measurements with radar tracks,” IEEE  Trans ., vol. 
 A. Soofi, and S. M. 
 “Pave mover TAWDS design requirements,” Hughes Aircraft Specification, November 1979,  unclassified, unlimited distribution. 95. J. 
 The areas of all three plates were fixed at 25 l2, hence all three  patterns rise to the same amplitude at broadside incidence (zero aspect). The center  pattern is for the disk, while the first and third are both for a square plate. However,  the square plate was oriented for a principal-plane pattern in the leftmost chart and like  a diamond ( f = 45°) in the rightmost chart. 
    ANDGSSTRACK V M4 6ARY RV TO INCREASE  DECREASE GAINS  AND OBTAIN DESIRED PERFORMANCE USING EQUATIONS IN 4ABLE 6ERY CONSERVATIVE WITH RESPECT TO FILTER STABILITY4!",%  #OMPARISON OF -ETHODS OF 4UNING +ALMAN &ILTER FOR 0RACTICAL 2ADAR 4RACKING 0ROBLEMS. Ç°ÎÓ  2!$!2 (!.$"//+ -ANEUVER -ODEL 1 
 TRACING /THER -ODELS AND 0ROPAGATION )SSUES  3TUDIES OF (& RADAR PERFORMANCE AT  LOW LATITUDES HAVE SHOWN THAT IT IS OFTEN NECESSARY TO INCORPORATE MODELS OF DYNAMICAL PROCESSES  EITHER BECAUSE THEY MANIFEST THEMSELVES DIRECTLY IN THE DOPPLER STRUCTURE OF RADAR ECHOES OR BECAUSE THEY ARE INDICATORS OF OTHER PHENOMENA THAT DO 5SEFUL MODELS IN THIS CATEGORY INCLUDE (7-   WHICH DESCRIBES THE  STRUCTURE OF THE ZONAL  AND MERIDIONAL NEUTRAL WINDS THROUGHOUT THE IONOSPHERE  AND 7"-/$  WHICH  DESCRIBES SCINTILLATION ARISING FROM SMALL SCALE IRREGULARITIES SUCH AS THOSE ASSOCIATED WITH SPREAD 
 The arrival of a high energy magnetron pulse caused the gas to ionise, presenting a short-circuit to the end of the quarter-wave line, which was re ﬂected as an open-circuit at the T junction. On reception, the rhumbatron acted as a resonant cavity (tuned to the magnetron frequency as part of the radar set-up procedure) and a second coupling loop connected the received signals to the mixer cavity, where the LO signal from the indicator unit was injected. The IF signal at 13.5 Mc/s was taken from the mixer to the IF ampli ﬁer. 
 52. T. B. 
 VERSA 4HE RESULT OF THE !$$35" BLOCKS IS STORED IN A REGISTER 2%'  ON THE NEXT CLOCK EDGE AND PASSED TO THE NEXT STAGE OF PROCESSING )N THIS IMPLEMENTATION THE LAST BLOCK LABELED 0!33).6  PERFORMS   THE REQUIRED INVERSION OF ) AND 1 IF THE DESIRED PHASE SHIFT IS BEYOND THE  o O RANGE OF  THE ALGORITHM 4HE FINAL MULTIPLICATION BY A CONSTANT IS OPTIONAL  AS DESCRIBED EARLIER 4HE ARCHITECTURE SHOWN IN &IGURE  IS A GOOD EXAMPLE OF A  PIPELINED PROCESSOR   IN WHICH A PORTION OF THE COMPUTATION IS PERFORMED AND THE RESULT IS STORED IN A REGISTER ON EACH RISING EDGE OF THE SAMPLE CLOCK AND PASSED TO THE NEXT STAGE OF PROCESSING 4HE PROCESSOR WOULD STILL FUNCTION IF THE REGISTERS WERE REMOVED (OWEVER  IN THAT CASE  WHEN THE INPUT ) AND 1 VALUES CHANGED  THE FINAL OUTPUT WOULD NOT BE USEABLE UNTIL THE RESULTS OF THE NEW INPUT VALUES RIPPLED THROUGH ALL OF THE STAGES OF PROCESSING  WHICH WOULD GENERALLY BE AN UNACCEPTABLY LONG PERIOD OF TIME )N A PIPELINED PROCESSOR  A SMALL PORTION OF THE TOTAL CALCULATIONS IS PERFORMED AT A TIME  AND THE RESULT IS STORED IN A REGISTER AND PASSED TO THE NEXT PROCESSING STAGE 4HIS ARCHITECTURE PROVIDES A HIGHER THROUGHPUT THAN THE NONPIPELINED VERSION  WHICH MEANS THAT THE FINAL RESULT CAN BE PRODUCED AT A MUCH HIGHER SAMPLE RATE  WHICH IS INVERSELY PROPORTIONAL TO THE DELAY OF A SINGLE STAGE 4HE  LATENCY OF A PIPELINED PROCESSOR REFERS TO THE DELAY EXPERIENCED  BETWEEN THE TIME A NEW DATA SAMPLE IS ENTERED INTO THE PROCESSOR AND THE TIME THAT THE RESULT BASED ON THAT INPUT IS AVAILABLE ON THE OUTPUT 4HE EIGHT 
 Res., vol. 82, pp. 4305-4315, September 1977. 
 The reasons for this are proposed to be related to the following: (1). Soft clay has the property of mellow soil, large natural water content, and high compressibility. During the period of June 2014 to June 2015, under the conditions of constant external load, the void between the soil mass was being compressed and the inner water was being released; thus, the deformation during this period was characterized as obvious subsidence with a decreasing velocity. 
 ENTLY TWO ORTHOGONAL LINEARLY POLARIZED COMPONENTS 3EE 3ECTION  FOR FUR 
 However, radar receivers with  vcry low ~ioise i~tpilt stages sornetit~les cat1 he affected by the ambient noise from the natural  environment. This is more likely to occur at both the upper and lower extremes of the micro-  wave frequency region. Several sources of ambient, or external, noise are described in this  sectiorl. 
 A one-way attenuation or 0.3 dB/km at 94 GHz might not be significant for short-range  radar, but it can be overwhelming for long-range radar. For example, a 5-km radar will  experience a two-way attenuation of 3 dB, which is tolerable in most situations. A 50-km  radar, however, will have 30-dB attenuation, which is usually intolerable. 
 Since these rough-surface models usually fail to explain the rise in return near vertical incidence, other simplified models combine Lambert's law and other rough-surface scattering models with specular reflection at vertical incidence, and a smooth curve is drawn between the specular value and the rough-surface prediction. Specular reflection is defined as reflection from a smooth plane and obeys the Fresnel reflection laws.33 At normal incidence, the specular-reflection coefficient is therefore r = % ~ ^o R % + T\O where TJO, TI^ are the intrinsic impedances of air and earth, respectively. The frac- tion of total incident power specularly reflected from a rough surface is5 e-2(2™h/\)2 . 
 Probability isameasure ofthelikelihood ofoccurrence ofanevent.Thescaleofprobabil­ ityrangesfrom0tol.tAneventwhichiscertainisassigned theprobability 1.Animpossible eventisassigned theprobability O.Theintermediate probabilities areassigned sothatthe morelikelyanevent,thegreaterisitsprobability. Oneofthemoreusefulconcepts ofprobability theoryneededtoanalyzethedetection of signalsinnoiseistheprobability-density function. Consider thevariablexasrepresenting a typicalmeasured valueofarandom processsuchasanoisevoltageorcurrent. 
 BASED CODE INTENDED FOR BOTH REFLECTOR SYSTEM  DESIGNANALYSIS AND SCATTERING ANALYSES '2!30 HAS POPULAR '5) 
 TRANSFORMATION TECHNIQUE v  )%%% 4RANSACTIONS ON !EROSPACE AND  %LECTRONIC 3YSTEMS  VOL !%3 
 When all three sets of data are considered as one, the dashed curve shows a  saturation of a0 with wind speed above about 20 knots. However, conclusions drawn from  viewing the three sets of data as a whole may not be fully valid because of the accuracy with  Wtnd velocity (knots)  (a)  -20 I I I I I I 7 I I  I  -70; I I I I I I I I I I 5 10 15 20 25 30 35 40 45 50  Wind velocity (knots)  (b)  Figure 13.4 Median value of a0 as a function of wind speed, for X band and 10" grazing angle. (a) Vertical  polarization, (b) horizontal polarization. 
 With modern high-speed aircraft, a bundle of chaff quickly separates  from the dispensirig aircraft and makes the job of discriminating between target and chaff  easier. However, chaff need not be sii~lply dropped from the target. It can be dispensed fro111  aerial rockets and fired ahead, behind, above, or below the target aircraft. 
 The coverage of a simple fan beam is usually inadequate for targets at high altitudes close  to the radar. The simple fan-beam antenna radiates very little of its energy in this direction.  However. 
 Thus, like lightrays in the standard atmosphere, radar rays are bent or refracted slightlydownwards approximating the curvature of the earth (see ﬁgure 1.7). The distance to the radar horizon does not in itself limit the distance from which echoes may be received from targets. Assuming that adequate poweristransmitted,echoesmaybereceivedfromtargetsbeyondtheradarhorizonif their reﬂecting surfaces extend above it. 
 The dashed lines in Figure 6indicated the true target positions. It could be seen that they were clearly separated and had the correct RCS when the proposed algorithm was used. In contrast, under the classical 2D focusing algorithm, the weaker scatterers (A and B) were seriously a ﬀected by the sidelobes of the strong scatterer C and could not be detected. 
 1715–1718. 16. T. 
 AEW  systems have generally been developed at lower frequencies—this can be understood  by reviewing the surveillance radar range equation:  RP A kTF L S Nta e t ns max( ) ( )=σ π40 0/Ω (3.1)Chapter 3 *  Sections 3.4 through 3.8 and 3.10 were taken primarily from the second edition of the Radar Handbook , Chapter 16,  authored by Fred Staudaher, with revisions made by James Day. The remaining sections of the chapter were  authored by James Day. ch03.indd   1 12/20/07   11:00:33 AMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Nov., 1964.  90. Butler, J. 
 Sweeping the LO moves the spectrum past the narrowband filter to accomplish acquisition as in the conventional speedgate. Doppler tracking is similarly accom- plished by controlling the LO frequency to keep the target in the narrow filter. The angle error signals required for guidance are extracted after the second IF amplifier. 
 Allphaseinformation isdestroyed. Itis alsopossible todesignadetector whichutilizesonlyphaseinformation forrecognizing targets. Anexample isonewhichcountsthe·zerocrossings ofthereceived waveform. 
 Trunk7)TABLE 7.6  Association Table for Example Shown in Figure 7.32* ch07.indd   39 12/17/07   2:14:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 Novcmbcr, 1976. 5.1.deLoor. G.P..A.A.Jurriens. 
 427-439,  April, 1969.  61. Greene, J.: Antenna Noise Temperature, AIL Advertisement, Proc. 
 22) and HF over-the-horizon radars (Chap. 24) might have average powers of the order of a megawatt. The radar equation (Sec. 
 BACK &" RATIO  IE  THE RATIO OF THE MAIN BEAM AND BACKLOBE GAINS 4HE ANALYSIS OF THESE REFLECTOR EDGE DIFFRACTION EFFECTS AND ASSOCIATED &" RATIOS FOR SOME COMMON REFLECTOR GEOMETRIES ARE DESCRIBED BY +NOP  &EED  "LOCKAGE  -ANY REFLECTOR SYSTEMS SUFFER FEED ANDOR FEED 
 Postamplificalion beamforming. Whenreceiving beamsareformedinnetworks placedafter theRFamplifiers, asinFig.8.25,theantenna issometimes calledapostamp/ijicatiotl heam­ forming array,abbreviated PABFA.Aseparate transmitting antenna maybeusedtoillumin­ atethevolume covered bythemultiple receiving beamsor,altern'atively, itispossible to transmit multiple beamsidentical tothemultiple receiving beams,usingtheradiating elements ofthesamearrayantenna. Notethatifthemultiple transmitting beamsarecontiguous andat thesamefrequency, thecomposite transmitted patternissimilartothepatternfromasingle beamencompassing thesameangular region. 
 The interference covariance matrix is further described in terms of  the individual noise, jamming, clutter, and signal contributions:  Rr = N I + KZ + RS (3.29) where N is receiver noise power, KZ is the covariance matrix for clutter (temporally cor - related) plus jamming (spatially correlated), and Rs is the signal covariance matrix. Taxonomy of STAP Architectures (Ward21). The application of the adaptive  weight equation from Eq. 
 With rapidly fluctuating signals, in fact, postdetection integration will provide greater detectability improvement than does predetection integration, as dis- cussed later in this section under the heading "Predetection Integration." Number of Pulses Integrated. The number of pulses integrated is usually determined by the scanning speed of the antenna beam in conjunction with the antenna beamwidth in the plane of the scanning. The following equation can be used for calculating the number of pulses received between half-power-beam- width points for an azimuth-scanning radar: M= _^ (2.16) 6 RPM cos 6e . 
 ................................ ....... 16  Probability of Detection  ................................ 
 V . Trunk, “Corrections to ‘angular accuracy of a scanning radar employing  a two-pole filter’,” IEEE Trans ., vol. AES-10, pp. 
 SPEED CLOSING TARGETS&)'52%  #LUTTER 
 If  we do not mind using a very high charging voltage, then,  of course, we need not be unduly troubled by the curved  nature of the first voltage-time curve we have examined.  Although its overall shape is thus e » we can produce  such a curve by a relatively high voltage, and then for  our time-base portion work on only a very small part of  this exponential characteristic, and the smaller the part  from which we work the nearer will be its approximation  to linearity. There are several time-bases which do, in  fact, have their condensers charged direct through a  resistance, but the high voltage is an obvious disadvan-  tage. 
 Parameters used to simulate raw SAR data. Parameters Units Carrier Frequency fc=5.300 GHz Chirp Duration Tc=37.12 μs Chirp Bandwidth Bch=15.50829 MHz Sampling Frequency fs=18.962 MHz Satellite height h=700 km Satellite speed vsat=11.75 km/s Off Nadir Angle θ=23 deg Squint Angle φ=0 deg The obtained raw data matrix was decomposed using the SVD algorithm. A large part of the energy in the data matrix is concentrated in the ﬁrst singular value, clearly stating that the ﬁrst left singular vector (i.e., the ﬁrst column of matrix U) should contain the orthogonal signal with maximum energy in the data. 
 Whitham, “A comparison of DSTO and DERA HF background Noise  measuring systems with the International Radio Consultative Committee (CCIR) model data,”  DSTO Technical Report DSTO-TR-0855, November 2000. 110. M. 
   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°x£ £Î°Ê *- 
 McGeogh, R. Pilon, G. Skaggs, and J. 
 LAYER  CON 
 Radar System Engineering  Chapter 4 – Information Content of Radar Signals  21     4.2 Velocity   In the case of continuous observation of the target (CW Radar) its radial velocity produces a phase  shift of the received signal, known as Doppler effect, from which follows:  € ωd=dϕ dt (4.5)  € fd=ωd 2π=1 2πdϕ dt=−2 λ0dr dt=−2vr λ0=−2vrf0 c0 (4.6)  € fd=Doppler frequency    € vr=radial velocity    € f0,λ0=transmission frequenncy ,wavelength   € c0=propagation velocity    As a rule  € fdHz[]=55,5⋅vkm /h[ ]λcm[].  With a movement diagonally for the direction of prop a- gation of the wave only the radial  component from v is to be considered vr.  The Doppler effect is  clear with CW Radar devices, in contrast to the coherent pulse Radar. 
 Phillips, D. E. Iglesias, and R. 
 Frequency  diversity over a wide band also makes it more difficult (but not impossible) for a hostile  intercept receiver or an antiradiation missile to detect and locate a radar signal. The Doppler Shift in Radar.  The importance of the doppler frequency shift  began to be appreciated for pulse radar shortly after World War II and became an  increasingly important factor in many radar applications. 
 Funding: This research received no external funding. Acknowledgments: The authors wish to thank Fabio Bovenga for the interest shown in this research and Davide Palmisano for his help in SAR raw data extraction and data formatting.Conﬂicts of Interest: The authors declare no conﬂict of interest. References 1. 
 hfrrror. Soc., vol. 88, pp. 
 FREQUENCY RADARS THAT ARE FAR MORE VERSATILE  BUT HIGH 
 GAIN REPEATER   4HIS  CAN BE PARTIALLY OVERCOME BY A CONICAL SCAN 
 F .. W. 11. 
 TION DATA  MAY BE PROVIDED BY SURVEILLANCE RADAR OR SOME OTHER SOURCE )T MAY BE SUF 
 Yl.Ylb is justified. Sometimes R, Gn or both are assumed con- stant over the illuminated area, but such an approximation to Eq. (12.18) should be attempted only after checking its validity for a particular problem. 
 Limiters causethespectrum ofstrongcluttertospreadintothecanceler pass­ band,andresultinthegeneration ofadditional residuethatcansignificantly degrade MTI performance ascompared withaperfectlinearsystem. Anexample oftheeffectoflimiting isshowninFig.4.32,whichplotstheimprovement factorfortwo-pulse andthree-pulse cancelers withvarious levelsoflimiting.s3Theabscissa appliestoagaussian clutterspectrum thatisgenerated eitherbycluttermotionwithstandard deviation CT,.atawavelengl hA.andaprffp,orbyantenna scanning modulation witha. 138 INTRODUCTION TO RADAR SYSTEMS  gaussian-shaped beam and ns pulses between the half-power beamwidth of the one-way  antenna pattern. 
 VELOCITY PRODUCT  H6 3# CORRESPONDING TO EACH ENTRY 4HIS PRODUCT IS A  SCALING FACTOR THAT CHARACTERIZES THE RANGE 
 bletomechanical vibration and shock. Most recent practice, therefore, istoadjust the regulator tooperate onthe right-hand side ofthe dip. When carbon-pile regulators were first used oninverters they were mounted directly onthe rotating machine. 
 This summa­ tion can be m~de at the computer and distributed to the MN elements of the array. Alterna­ tively, M + N control signals can be transmitted to the array if an adder is provided at each  phase shifter to combine the azimuth and elevation phases.  In the series-series feed each of the M columns of an M by N array utilizes a series  arrangement to produce steering in one coordinate (say elevation). 
 AP-34, no. 8, August 1986.FIGURE 26.17  AREPS signal-to-noise ratio versus range for surface-search radar and small missile  target—clutter-to-noise ratio superimposedFree-space range re ference100 60 0 20 APM computed S/N ratio APM computed clutter to noise ratio40 60 Range (nmi)Height = 100.0ft Signal to noise (dB) 80 10020 −20 −60 −100Skip-z one signal f alloff ch26.indd   27 12/15/07   4:53:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The skin depth or attenuation  length is 1/ a [m]; the distance electromagnetic energy travels while being attenuated  by 1/e in amplitude. This distance is known as the skin depth, d, and provides an initial  guide to the useful penetration depth of a GPR system although in some media the  useful range may be greater. The individual propagation constants can be written as  α ωµε ε εωµε ε=′+′′ ′  −    =′+′′ 21 1212 b′ ′  +     ε2 1  where   a  = attenuation factor   b  = phase constant and the dimensionless factor e″/e′ is more commonly termed the material loss tangent. 
 Aninteresting array-type antenna which reached ahighly developed experimental stage istheLong Range, Aircraft toSurface Vessel, LRASV, corrugated coaxial line array. This antenna was designed tobeused with a10-cm system, mounted asalong array feeding areflector along the side ofanairplane, giving abeam 0.8° by9°forlong-range search. The array, shown inFig. 
 ALIGNS RADAR  AND SEEKER 3INCE GUN EFFECTIVE RANGES  ARE VERY SHORT  GUN RANGING CAUSES THE RADAR TO SENSE THE GUN FIELD OF FIRE  PREDICTS ANGLE RATE  AND MEASURES RANGE TO A TARGET FOR TENTATIVE GUNFIR E  )T MAY ALSO TRACK GUN  ROUNDS DURING FIRE 4HERE ARE THOUSANDS OF ELECTRICAL DEGREES OF PHASE BETWEEN FREE  SPACE AND THE !$  CONVERTERS 4HE COMBINATION OF TEMPERATURE  TIME  AND MANUFACTURING TOLERANCES GIVES RISE TO THE NEED FOR SELF CALIBRATION  TEST  FAULT DETECTION  FAILURE DIAGNOSIS  AND NEEDED CORRECTIONS  WHICH ARE PERFORMED BY A SUBSUITE OF PERFORMANCE MONITOR SOFTWARE 4IMING 3TRUCTURE  4HE SIGNIFICANCE OF THE REMAINING PARAMETERS IN 4ABLES   AND  CAN BEST BE ILLUSTRATED WITH A TIMING STRUCTURE TYPICAL OF FIGHTER RADARS      &IGURE  SHOWS A MODERN RADAR TIMING STRUCTURE IN A SEQUENCE OF PROGRESSIVELY EXPANDED TIMELINES 4HE FIRST ROW OF &IGURE  SHOWS A TYPICAL SCAN CYCLE COVERING THE REQUIRED VOLUME OF INTEREST FOR A SPECIFIC MODE 4HE TIME SPAN FOR A FULL SCAN CYCLE MIGHT BE  TO  SECONDS )NSIDE THE TOTAL SCAN CYCLE TIME  THERE MAY BE SEVERAL BARS OF A SCANNED REGION OF SPACE WITH A TIME SPAN OF A FEW TENTHS OF A SECOND ! BAR IS A SCAN SEGMENT ALONG A SINGLE ANGULAR TRAJECTORY  AS SHOWN IN &IGURE   LATER IN THE CHAPTER  2ADAR -ODES02&K(Z 0ULSE7IDTHMSEC $UTY2ATIO 0ULSE#OMP2ATIO&REQ,OOKS0ULSES0ER #0))NSTANT"AND 
 Two kinds of modification may be used, separately or jointly: considering the actual reradiation pattern of finite-size facets at finite wavelengths36 and con- sidering the effect of wavelength on establishing the effective number of facets.37 Thus the scatter from a facet may actually occur in directions other than that requiring that angle of incidence equal angle of reflection. Figure 12.5 illustrates this. For large facets (compared with wavelength) most of the return occurs almost at normal incidence, whereas for small facets the orien- tation may be off normal by a considerable amount without great reduction in scatter. 
 G. Tomlinson, “Distributed array radar,” IEEE Trans .,  vol. AES- 19, pp. 
 Average these new Pd values across the IPP. The result will be a new detection curve including the average effect of eclipsing and  range gate straddle. For a fixed Pd, the difference in SNR between the uneclipsed and  the eclipsed detection curves is the average eclipsing and range gate straddle loss. 
 The duct is,inasense, awaveguide. Let usconsider anoversimplified model ofaduct inwhich theindex ofrefraction, nl,isconstant from the surface uptosome height a,where itabruptly changes tonz(Fig. 2“15). 
 4: Constantly  accelerating target with   a white noise jerk   j [(g/s)2/Hz] sampled by radar  measurement. (Jerk is the rate  of change of acceleration.) 50,51jT T T T T T T TTk k k k k k k k k5 4 3 4 3 2 3 220 8 6 8 3 2 6 2Steady-state gain calculations  described in Fitzgerald.49 and γσtrack=jT m5 2 .Select this model when  target is known/   expected to be  accelerating.Zero lags to constant  acceleration; however, noise  errors are much greater.50 Model no. 5: Constant,  deterministic acceleration  a (g). 
 For instance, this may just include the coastline, navigation marks,  and a single depth contour, considered safe for the draught of the ship. If the ship is  navigating on ECDIS, rather than a paper chart, it is likely that both the radar and  the ECDIS will be commonly set to Course-up or Head-up modes. North-up is no  longer a particular advantage when the chart is not confined to such a presentation,  such as paper charts. 
 PORTIONAL TO THE AVERAGE SCENE INTENSITY #ARRARA ET AL DEFINE MULTIPLICATIVE NOISE AS FOLLOWS h4HE PRINCIPAL CONTRIBUTORS TO  MULTIPLICATIVE NOISE ARE THE INTEGRATED SIDELOBES OF THE SYSTEM IMPULSE RESPONSE  THE  ENERGY PRESENT IN THE SCENE AS A RESULT OF RANGE AND AZIMUTH AMBIGUITIES  AND DIGITAL ;IE  FROM QUANTIZATION IN THE ANALOG 
 61. Siegel, K. M., H. 
 3.1. Signal Model The geometry of the ISAR system is depicted in Figure 3, where the radar is located at r(0, 0, h)i n the (X, Y, Z) coordinates system. The reference coordinates system ( z1,z2,z3) is set at the target point p(x0, y0, 0). 
 59. Mallett, J. D., and L. 
 Repr. TE-77-14, June. 1977. 
   AND DOUBLE 
 Observations indicate that the liquid-water concentration in clouds generally ranges from18 1 to 2.5 g/m3, al- though Weickmann and aufm Kampe19 have reported isolated instances of cumu- lus congestus clouds with water contents of 4.0 g/m3 in the upper levels. In ice clouds, it rarely exceeds 0.5 and is often less than 0.1 g/m3. The attenuation due to cloud drops may be written12 K = K1M (23.15) where K = attenuation, dB/km K1 = attenuation coefficient, dB/(km • g • m3) M = liquid-water content, g/m3 M = ^iX (23.16) 3 /=i K1 = 0.4343^Im(- ^r^} (23.17) x \ m2 + 2/ where the at are droplet radii, p is the density of water, and Im is the imaginary part. 
 5.1. The DEM Accuracy Analysis5.1.1. Phase Error Analysis as the Decrease of the SNR Caused by Image Defocusing Defocusing causes the decrease of the SAR image’s SNR, which results in larger phase error. 
 Each element of an array or incremental section of a continuous aperture can be con - sidered as receiving a doppler-shifted signal due to the relative motion of the clutter.  The power received by the element is proportional to the two-way aperture power  distribution function F2(x) at the element. In addition to the velocity seen by all elements because of the motion of the plat - form, each element sees an apparent clutter velocity due to its rotational motion, as  illustrated in Figure 3.14 b. 
 EXAMPLES OFTHE MAJOR OPERATIONAL REQUIREMENTS 6.9. Early Aircraft-warning Radar. l—The British HomeChain.—The first radar tohave actual combat usewas theBritish CH (Chain, Home) equipment. 
 In Figure 5it is clear that the signal frequency coherence decays dramatically for L0≥40km, whereas the spatial coherence shows little difference with the increase of outer scales. For a general comparison, the signal spatial coherence is more sensitive to the scintillation strength and spectral index than outer scales. Furthermore, the signal correlation declines more signiﬁcant with the increasing of spatial separation which means the spatial variation of beam central incident angle is considerable. 
 Amplifiers with again of120dband anover-all i-fbandwidth ofabout 2Me/see will require astage bandwidth ofover 6Me/see, which permits again ofapproximately 7,or17db. Thus seven stages will berequired. Assuming ag~of7000, areasonable figure fora6AC7, theload resistance R.would be1000 ohms [Eq. 
 334-339, November, 1967.  21. Ternes, C. 
 P. Lutte, and M. W. 
 V  ,V >À`Ê °Ê Ài 4HE 5NIVERSITY OF +ANSAS £È°£Ê  /," 1 /"  2ADAR GROUND RETURN IS DESCRIBED BY  R   THE DIFFERENTIAL SCATTERING CROSS SECTION  OR  SCATTERING COEFFICIENT SCATTERING CROSS SECTION PER UNIT AREA   RATHER THAN BY THE TOTAL  SCATTERING CROSS SECTION  R  USED FOR DISCRETE TARGETS 3INCE THE TOTAL CROSS SECTION  R  OF  A PATCH OF GROUND VARIES WITH THE ILLUMINATED AREA THAT IS DETERMINED BY THE GEOMETRIC RADAR PARAMETERS PULSE WIDTH  BEAMWIDTH  ETC    R   WAS INTRODUCED TO OBTAIN A COEF 
 For rays ofsmall inclination tothe hori- zontal, and forheights small compared tothethickness oftheatmosphere, this effect can betaken into account byreplacing the true diameter of the earth byasomewhat larger number D.11.How much larger itis depends ontherate ofchange with height oftheindex ofrefraction ofthe atmosphere. This effect may beexpected toshow local variations. A reasonable choice ofa”standard” condition leads toavalue R.~r=1.33R0, and thence, thanks toafortuitous numerical relation between units, to aneasily remembered formula forthedistance totheradar horizon, R,(statute miles) =~2h (feet). 
 Hubbard, J. V.: Digital Automatic Radar Data Extraction Equipment, J. Brit. 
 SFDR is typi - cally expressed in decibels (dB). This parameter is determined by a variety of factors  including the mixer intermodulation spurious (described in more detail in Section  6.4), the spurious content of the receiver local oscillators, the performance of the A/D  converter, and the many sneak paths that may result in unwanted signals coupling onto  the receiver signal path. Intermodulation Distortion (IMD). 
 MIT AND RECEIVE BEAMS WOULD NEED TO BE SEQUENTIALLY SCANNED TO EACH BEAM POSITION )NCREASING THE NUMBER OF BEAMS IN THE RECEIVE CLUSTER  WHILE ALSO INCREASING THE TRANSMIT BEAM SPOILING BY AN EQUIVALENT AMOUNT  REDUCES THE SEARCH FRAME TIME 4HERE IS ANOTHER TECHNIQUE FOR GENERATING MULTIPLE SIMULTANEOUS BEAMS THAT DOES  NOT USE BEAM BROADENING ON TRANSMIT )N THIS TECHNIQUE  EACH PULSE IN THE WAVEFORM IS DIVIDED INTO AS MANY SEGMENTS AS THERE ARE BEAM POSITIONS ! PULSE SEGMENT IS TRANSMIT 
 The eﬀectiveness of the proposed method was veriﬁed by experiments. Keywords: synthetic aperture radar (SAR); ground-based synthetic aperture radar (GBSAR); arc-scanning synthetic aperture radar (ArcSAR); interferometric ArcSAR; DEM assisted SAR imaging 1. Introduction Synthetic aperture radar (SAR) is capable of high-resolution imaging all-day and all-weather conditions [ 1,2]. 
 57. Skolnik, M. I.: An Analysis of Bistatic Radar, IRE Trans., vol. 
 Theuseofaneffective earth'sradiusimpliesthatdn/dhisconstant withheight,orinother words,that"decreases linearlywithheight.Thisassumption isindisagr~cd1cnt withtht: experimentally observed refractive-index structure oftheatmosphere atheightsaboveIkm.17 Thevariation ofrefractivity withaltitudeisfoundtobedescribed morenearlybyanexponen­ tialfunction ofheightratherthanthelinearvariation assumed bythetearthmodelorany modelofconstant effective earth'sradius.Amoreappropriate refractivity modelisonein whichtherefractivity variesexponentially withheight,12.17 IN=N,exp[-ce(h-hs)] (12.12) where N,=refractivity atsurfaceofearth h=altitudeoftarget h,=altitudeofradar Ce=In(Ns/N1)=aconstant whichdepends uponvalueofNsandN1>thelatterbeingrefrac­ tivelyataltitudeof1km Itisfoundthattheexponential modelgivesamoreaccurate determination oftheeffectsof atmospheric refraction thandoesalinearmodel. Theuseofthecorrectatmospheric modelisquiteimportant inaheight-finder radar,' especially fortargetsatlongranges.12,17,18Refraction causestheradarraystobend,resulting inanapparent elevation angledifferent fromthetrueone.Incertainradarapplications, corrections mustbemadetotheradardatatoobtainabetterestimate ofelevation angle, range,orheight.19Surface observations ofrefractivity oftensufficeforascertaining the effectsofrefraction.2Q-22 Refraction istroublesome primarily atlowanglesofelevation, especially atornearthe horizon.Itcanusuallybeneglected atanglesgreaterthan3to5°inmostradarapplications. Although mo~erefinedmodelsofatmospheric refraction mustbeconsidered where preciseradarmeasurements areimportant, thesimplicity oftheusualtearthapproximation makesitattractive forroughpredictions. 
 between the radar and the geometrical horizon) is essentially the same as in free space. The  field docs not penetrate beyond the horizon. Thus, for optical frequencies or very short radar  OJ u  0 a. 
 SCALE METEOROLOGICAL MODELS SUCH AS THE 53 .AVY #OUPLED /CEAN!TMOSPHERE -ESOSCALE 0REDICTION 3YSTEM #/!-03   2ADIOSONDE DATA MAY BE MANUALLY  ENTERED OR AUTOMATICALLY DECODED FROM EITHER THE 7ORLD -ETEOROLOGICAL /RGANIZATION 7-/  OBSERVATIONAL MESSAGE FORMAT OR A FREE 
 The detection  of targets from an airborne platform places severe demands on radar design in order to reduce  or eliminate clutter that enters the radar receiver via the main beam. This is done in a  conventional A MTI radar by signal processing (filtering) as described in Sec. 4.11. 
 HK covers the largest subsidence area, and is the main commercial district of the city. QSIZ is the city’s oldest and biggest industrial area, and there are many large manufacturing plants, such as Wuhan Iron and Steel (Group) Corporation, Wuhan Petrochemical Complex, and Qingshan Thermal Power Plant. NSL has been undergoing rapid economic growth and high intensity of urban construction over the years. 
 1966. 61.Becker,J.E.•andJ.-C.Sureau:Control ofRadarSiteEnvironment byUseofFences.IEEETrailS. vol.AP-14,pp.768-773, November, 1966. 
  
 The VA-146N produces a 2.5 MW  peak power with a 20 µs pulse at a 0:004 duty cycle over a It dB bandwidth of 500 MHz at C  band. The gain is 31 dB and the efficiency at midband is 40 percent.  6.6 CROSSED-FIELD AMPLIFIERS  The crossed-field amplifier (CF A), like the magnetron oscillator, is characterized by magnetic  and electric fields that are perpendicular to each other. 
 ASV equipment should provide long-range detection over a wide ﬁeld in all directions from the aircraft. It should provide for display of information to determine if the detected craft is friendly or doubtful. The indication should enable the detectedtarget to be closed, and include display of information on type of target. 
 1.2 \ +-4 \--- ----Radar Y’&’’@’”a’ 5Target .4!... -_&.- ~ Radar +) Yz’o’ti’”e’Target JL~~=~(c) ,% Radar _L...__.,:>( “ @@3 Target ....$~L =+9-- .— Radar FIG. 1.2.—The principle ofpulse radar. 
 Most practical pulsers donot produce aperfectly uni- form flat-top wave because this isusually costly and unrewarding. A drop of2to5percent involtage during thepulse, AV~,, can usually be tolerated bythe magnetron without harmful frequency modulation or mode instability.. 366 THE J1.1G.\-L.’T1N3.V A,VD THE Pl:LSER [SE(-.108 The rate ofrise and theovershoot onthe leading edge ofthe~wltage wave are important indetermining the ability ofthe magnetron to operate athigh power levels. 
 ¶ 4HERE IS NO GOOD  SIMPLE ANSWER TO THIS QUESTION  BUT IN THIS SECTION WE SHALL ATTEMPT TO DISCUSS SOME OF THE VARIOUS ISSUES THAT MIGHT BE INVOLVED 4HIS CHAPTER HAS BRIEFLY DESCRIBED THE VARIOUS VACUUM TUBES THAT HAVE BEEN USED OR  CONSIDERED FOR RADAR APPLICATIONS  AND THE NEXT CHAPTER DISCUSSES THE SOLID 
 Individual time-delay circuits (Sec. 7.7) are normally too cumbersome to be added to each radiating element. A reasonable compromise may be reached by adding one time- delay network to a group of elements (subarray) where each element has its own phase shifter. 
 Ayliffe, “An extension of probabilistic data association to include  track initiation and termination,” in 20th IREE Int. Conv. Dig. 
 East, T. F. Haddock, and M. 
 At the higher frequencies (X band or above) atmospheric absorption is the predominant  contributor to the brightness temperature, while at the lower frequencies (L band or lower),  the cosmic noise predominates;' ThercVexists a broad minimum in the brightness temperature  extending from about 1,000 to 10,000'.MHz. It is in this region that it is advantageous to  operate low-noise receivers to· 'achievtf maximum system sensitivity. The minimum atmo­ spheric absorption occurs when the·'antenh.a 'is vertical (pointed at the zenith), while the . 
 ---- - -  amplifier filter Figure 5.4 (a) Pulse train with coni-  I  Delay voltage V,  Figure 5.5 Hlock diagram of Ihc AC;C portion of a trackit~g-radar receiver.  ..... '- "-"..­..­ / /'­" (a) -------"----- -------'-----'-- (b)TRACKING RADAR157 Figure5.4(a)Pulsetrainwithconi­ cal-scan modulation; (h)samepulse trainafterpassingthrough boxcar generator. 
 Simonett, “K-band radar in vegetation mapping,” Photog. Eng. and Rem. 
 ITY IS DERIVED FROM THE SPECIFIED FALSE REPORT TIME FOR THE SYSTEM 2ADAR 2ANGE %QUATION  )N THE DOPPLER REGION WHERE THE SIGNAL DOES NOT FALL IN  CLUTTER  PERFORMANCE IS LIMITED ONLY BY SYSTEM NOISE 4HE SIGNAL 
 57, pp. 590–593, 1969. 182. 
 The RF  oscillator feeds the pulsed amplifier, which transmits the pulses. The RF oscillator FIGURE 2.1 (a) Normal video and ( b) MTI video: These PPI photographs show how effective an MTI  system can be. Aircraft appear as three consecutive blips in the right-hand picture because the camera shutter  was open for three revolutions of the antenna. 
 He concludes that 25 to 37 elements are required  to provide a good indication. Figure 13.16 shows the change in the measured active  element pattern as the number of elements is increased. For a 41-element array, the  null is very pronounced. 
 If we picture a string of pulses, (- a ~~} Output  Gating  puises  il  FIG. 17  such as in Fig. 18, applied to the control grid they will  have no effect at the anode of the valve, for there is no  anode current flow. 
 Thedevelopment ofthemagnetron wasoneofthemostimportant contributions totherealization ofmicrowave radar. Thesuccessofmicrowave radarwasbynomeanscertainattheendof1940.Therefore the UnitedStatesServiceLaboratories chosetoconcentrate onthedevelopment ofradarsatthe lowerfrequencies, primarily theveryhighfrequency (VHF)band,wheretechniques and components weremorereadilyavailable. Theexploration ofthemicrowave regionforradar application becametheresponsibility oftheRadiation Laboratory, organized inNovember, 1940,undertheadministration oftheMassachusetts Institute ofTechnology. 
 FREQUENCY  LAND 
 Kell's complex targets are defined as an assembly of discrete scattering cen- DOWNRANGE (ARBITRARY UNITS) . BISTATIC ANGLE 0 (degrees) FIG. 25.7 Theoretical bistatic RCS for two perfectly conduct- ing spheres, where a = sphere radius and A. 
 Thorn, H.: Distribution or Extreme Winds in the United States, ASCE Trans., vol. 126, pt. II, paper  3191, 1961. 
 Any use is subject to the Terms of Use as given at the website. The Radar Transmitter.  THE RADAR TRANSMITTER  10.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 A solid-state cathode modulator can provide pulse widths varying from 50 ns to “dc”  on a pulse-to-pulse basis and can support pulse repetition frequencies up to 400 kHz.52  The high voltage solid-state switches are built from modules that might contain from  4 to 20 individual transistors connected in series to provide the required transmitter  cathode voltage. Rise times can be as low as 30 ns. 
 12.1 toan “electronic” PPI without moving parts, orbyaslight variation into an RHI. The range sweep ofaPPI can beconsidered asmade upoftwo orthogonal sweeps with speeds proportional tosin0and coso(see sketch 4Antenna e I c1Data transmitterI Fm.12.2.—Rotating-coil PPI. r?-t-—L~ %1I]#21RM=,—w o~. 
 X2.Leth-Fspensen. L.:Evaluation ofTrack-While-Scan Computer Logics. chap.29of"Radar Techniques forDetection. 
 275-283, February, 1964.  110. Lane, J. 
 This combination hasbeen useful asanaidin effecting rendezvous and foridentification. 4.Portable beacons. Such acombination has been ofmilitary use under circumstances where fixed ground beacons could not beset upreadily, but small portable beacons could beused instead. 
         B=   4HE 'RAY CODE IS ALSO USED IN CERTAIN HIGH 
 The CEA seems to be  the preferred tube for UHF-TV transmitters, rather than other types of grid-controlled  tubes, solid-state, or klystrons. It would seem that the CEA ought to be of interest for  radar applications at frequencies as high as 1000 MHz when highly shaped pulses  need to be used. ch10.indd   22 12/17/07   2:19:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
   3EPTEMBER   , " 6AN "RUNT   !PPLIED %#-  VOL   $UNN ,ORING  6! %7 %NGINEERING  )NC    2 ' 7ILEY   %LECTRONIC )NTELLIGENCE 4HE !NALYSIS OF 2ADAR 3IGNALS   .ORWOOD  -! !RTECH  (OUSE  )NC    2 ' 7ILEY   %LECTRONIC )NTELLIGENCE 4HE )NTERCEPTION OF 2ADAR 3IGNALS   .ORWOOD  -! !RTECH  (OUSE  )NC    2 ' 7ILEY   %,).4 4HE )NTERCEPTION AND !NALYSIS OF 2ADAR 3IGNALS   .ORWOOD  -! !RTECH  (OUSE  )NC    2 ! 0OISEL  %LECTRONIC 7ARFARE 4ARGET ,OCATION -ETHODS   .ORWOOD  -! !RTECH (OUSE  )NC    % 0 0ACE   $ETECTING AND #LASSIFYING ,OW 0ROBABILITY OF )NTERCEPT 2ADAR  .ORWOOD  -! !RTECH  (OUSE  )NC    $ # 3CHLEHER  h,0) RADAR &ACT OR FICTION v  )%%% !%3 -AGAZINE   VOL   NO   PP n    -AY   3 , *OHNSTON  h0HILOSOPHY OF %##- UTILIZATION v  %LECTRON 7ARFARE   VOL   PP n    -AYn*UNE    - 6 -AKSIMOV  ET AL   2ADAR !NTI 
 OUS PROBABILITY DISTRIBUTIONS OF CLUTTER AMPLITUDE  AFTER 0RENGAMAN ET AL    Ú )%%%  . Ç°{È  2!$!2 (!.$"//+  6ERY LOW SINGLE 
 Atthe end ofthetransmitted pulse, the discharge across thegaps goes outand thesystem isready toreceive echo signals. The impedance attheT-junction looking toward themagnetron isinfinite because there isanopen circuit half awavelength away. 1Microwave Dupb%rs, Vol. 
 POWER SYSTEMS AND WHERE ADDITIONAL  BITS ARE NEEDED FOR THE LOW PHASE ERRORS REQUIRED FOR LOW 
 DIMENSIONAL  DISPENSING WITH THE NEED FOR A FLARED SEC 
 POLARIZATION OPERATION 7HEN CIRCULAR  POLARIZATION IS NEEDED IN A PARABOLOID 
 Robust uncertainty principles: Exact signal reconstruction from highly incomplete frequency information. IEEE T rans. Inf. 
 E., and D. W. Maki: An Integrated-Circuit Balanced Mixer, Image and Sum Enhanced,  IEEE Trans., vol. 
 If  tlie desigrl sidelobe level is 25 dB, a Taylor pattern with ii = 5 gives a beamwidth 7.7 percent  grc;ltcr tiiarl tlic Ilolpli-Cliebyshev, and wit11 ir = 8 it is 5.5 percent greater.  -1'lie I'aylor pattern is specified by two parameters: the design sidelobe level and ,I, wliich  defines the boundary between uniform sidelobes and decreasing sidelobes. The integer fi  catlnot be too small. 
 An alert, motivated, and well-trained operator should perform as well as  described by theory. However, when distracted, tired, overloaded, or not properly trained,  operator performance will decrease. There is little guidance available on how to account for  the performance of an operator. 
 J. E., and M. J. 
 FIG. 15.25 Shaped-velocity-response feedforward cancelers compared with three-pulse feedbac canceler. See text for five-pulse canceler parameters. 
 Note that the spacecraft had to  be yaw-steered to maintain this footprint geometry over the rotating Earth. The C band  operating frequency, although a departure from space-based precedent, resulted from  use of the same RF hardware as the SAR mode. As a consequence, simultaneous SAR  and scatterometer operations were not possible. 
 TION )N ADDITION  THE FOLLOWING CONSTRAINTS APPLY ONLY ONE MODE IS EXERCISED DURING ONE  
 DETECTION CHARACTERISTICS 0REVIOUSLY  A VARIETY OF LIMITING OR LOGARITHMIC RECEIVER APPROACHES WERE USED TO PERFORM VARIOUS SIGNAL 
 4.4. Isolation. Each intermediate stage of a chain must see proper load match even if the following stage has high VSWR input, as in a typical broadband klystron, or even if it has significant reverse-directed power coming back from it, as is the case with CFAs. 
 When scanning is limited, the value of s/l may be  increased, for example, to s/l < 0.53 for scanning to a maximum of 60 ° or s/l < 0.59  for scanning to a maximum of ±45°. For larger values of s/l, grating lobes occur at angles q1, given by  sin s in/θ θλ1 0= ±n s (13.10) when n is an integer. In the limit, the inequality (Eq. 
  $ #+#*% *($    , "" %$%," , 
 #/5.4%2-%!352%3   Ó{°x£ NOISE JAMMER LEADING TO A *.2 IN THE RAW DATA OF ABOUT  D" WHEN THE JAMMER  PASSES THE CENTER OF THE MAIN BEAM  IS DEPICTED 4HE DE 
 AirForceCambridge Nesearch Cencer. December. 1956.AD117015. 
 Typically, target ran - dom motion is limited to small aspect changes such that the amplitudes of the echoes  from the individual reflectors vary little over a period of a few seconds, and change in  relative phase is the major contributor. Exceptions are large flat surfaces with narrow  reflection patterns. An example of a target configuration is a distribution of reflecting surfaces that  change in relative range with target motion. 
 ch07.indd   55 12/17/07   2:15:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
  
 As few guides are more than a few yards  long, this loss is unimportant.  By careful design it is possible to introduce even sud-  den bends into the guide, and when it is required to  radiate the microwave energy into space the wave-guide  itself is simply opened out into a ‘flare,’ or horn. This  horn opening may face a reflector, of course, to direct  the energy and thus to beam the transmission. 
 I..RFsection--_.··_-----.,-+---Colleclor I Fi~lJr('6.9Diagrammatic rcprescntation oftheprincipal partsofathree-cavity klystron.. 202 1NTRODUCTlON TO RADAR SYSTEMS  cavities to provide additional bunching, and hence, higtier gain. The gain of a klystron can be  typically 15 to 20 dB per stage when synchronously tuned, so that a four-cavity (three-stage)  klystron can provide over 50 dB of gain. 
 Conf., Apr. 6-8, 1976. 30. 
 FIGURE 3.10  Effect of platform motion on the MTI improvement factor  as a function of the fraction of the horizontal antenna aperture displaced per  interpulse period, VxTp/a ch03.indd   10 12/15/07   6:02:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 
 Antenna directiv - ity is an imposing calculation requiring volume integrals, but typical reflector pattern  computation codes express the pattern in terms of directivity, and the antenna losses  are generally accounted for separately. In the text that follows, reflector directivity is  described based upon available “aperture gain” and associated radiation losses. This  approach should be intuitive to the radar engineer. 
 Colorcanbean"attention-getter," andcanimprove theaccuracy ofrecognition. IIIanMTIradarwithasynthetic-video displaythatpresents onlymovingtargets,theclutter thatisrejected (therawvideo)canbesuperimposed onthedisplay byshowing itina difTcrcl1tcolorthanthesynthetic-videotargets.(Thedisplayofweatherclutterisofimportance totheairtrafficcontroller toavoiddirecting aircrafttoareasofsevereweather. Thedisplay oflandclutterisalsoofimportance insomeapplications soastoprovidereference landmarks.) Inprinciple. 
 $J  =    WHICH  IS PRESENTED AS IT WOULD BE CALCULATED USING COMPLEX IMAGE DATA (ERE   %;= IS  THE EXPECTATION AVERAGING  OPERATOR 4HE PHASE DIFFERENCE  $I MAY BE DUE EITHER TO  GEOMETRIC OR TO TEMPORAL DIFFERENCES BETWEEN THE TWO OBSERVATIONS 3UCCESSFUL INTER 
 In later-generation, more sophisticated systems, homing generally lasts for only the last few seconds of flight (typically 10 guidance time constants). In these systems, a midcourse phase (inertial, beam rider, or command) is employed to get the missile to an appropri- ate point on its trajectory, where it acquires the target (using prelaunch or in- flight commanded designation data) and enters the terminal (homing) phase of its flight. This is more efficient from the standpoint of both missile trajectory and radar power. 
 Diplex operation can be implemented with a variety of  approaches. Complete replication of the receiver channels is typically the most expen - sive approach and may be required if the frequency separation is very large. A more  common approach is separation of the frequencies at the first IF, as this does not  require complete duplication of the RF front end or the first LO signal. 
 of  Electrical and Electronics Engineers, Inc., New York, 1977.  61. Anonymous: News item in Aviation Week and Space Technology, vol. 
 Hence, we accept even aweak indication ofthepresence ofsignal ifitcomes near the expected place, with comparatively small chance oferror. Inthe former case, however, alarge area oftheradar scope must bekept under surveillance foralong time. The likelihood that ahigh noise peak will beobserved ismuch greater: only avery pronounced peak can now be confidently identified asanew signal. 
 (Yun Lin) contributed materials. Y.L. (Yang Li) and Y.Z. 
 In order to fully utilize the forward and the backward signal, we will merge them with the original signal in the azimuth direction (i.e., the slow time domain). Then the newly merged signal in one range cell can be expressed as: ˆs(τ,1: N+2P)=⎭bracketleftBig sb(τ,N−P),...,sb(τ,N−1),s(τ,1)...,s(τ,N),sf(τ,N+1),...,sf(τ,N+P)⎭bracketrightBig (30) where ˆs(τ,1: N+2P)is the newly merged signal in the azimuth direction. One important problem is how to determine the order of the AR model. 
 32. Andrews. G. 
 Finally, there are various other antenna software  modules available from TICRA that can be used in conjunction with GRASP. One  notable example is Physical Optics Shaper (POS), an optimizer module for shaped  reflector synthesis and/or feed array amplitude/phase weight synthesis. More informa - tion is available at www.ticra.com. 
 These inverters are show-n inFigs. 14.16 and 14.17. Inmost radar applications, such arange infrequency isnotobjection- able. 
 Work on a blind navigation device for Bomber Command started in October 1941 and on 29 December 1941 Bernard Lovell (later Sir Bernard Lovell) was instructed to stop hiswork on AI and take charge of the development team at TRE [ 2]. In December 1941 contracts were placed with EMI for the manufacture of 50 complete H 2Su n i t s .T h e EMI team was led by A D Blumlein [ 3], a pioneer in the development of television and widely regarded at that time as one of the best electronic engineers in the country [ 2]. Early work at EMI concentrated on the development of a klystron transmitter but this was overtaken by the magnetron design developed by TRE. 
 Table 7.2. Detection ranges of U-class submarines, aircraft height 1000 ft (**: ‘moderate ’sea; *: ‘slight to moderate ’sea). RadarAverage detection range, beam aspect, nmiAverage detection range, end-on aspect, nmi ASV Mk. 
 GENT CLUTTER CANCELLATION REQUIREMENTS OF  MODERN RADARS MEANS THAT THE PHASE NOISE OF  ALL OSCILLATORS AND TIMING JITTER OF !$ CONVERTER AND $! CONVERTER CLOCKS AND 42 STROBES MAY BE SIGNIFICANT 4HE SHORT 
 271. Sensors 2019 ,19, 2605 From the ground truth map, the actual number of pixels belonging to the unchanged class and changed class are calculated, denoted as Nuand Nc, respectively. With this information, ﬁve objective metrics are adopted for quantitative evaluation. 
 The five-cavity gyroklystron  could achieve a bandwidth of 1050 MHz at an average power of 4 kW. The radar used  a 6 ft diameter antenna that provided a beamwidth of 0.1°. This W-band Warloc was  installed in a van and was used for various experiments. 
 This is the concept introduced by Mitzner,41 and the summation of the fields diffracted by the edge elements im- plies an integral around the edge contour. (Although Mitzner's most significant results are embedded in a government document of limited distribution, we in- clude this source in our references because of its significance.) However, Mitzner sought the fields scattered in arbitrary directions, not just those along the local Keller cones, and for this purpose he developed his conceptFrustum length = 24.324 XMinimum diameter = 4.779 \Maximum diameter = 13.363 XGEOMETRICAL DIFFRACTION THEORY AZIMUTH ASPECT ANGLE a (degrees) AXIS OFSYMMETRYMEASUREMENT LINE OF SIGHT VERTICALPOLARIZATIONRADAR CROSS SECTION (dBsm) . AZIMUTH ASPECT ANGLE a (degrees) FIG. 
 In fact. the larger tlie number of pulses integrated, the more likely it will  tw for. the fl irctuatioris to average out, and cases 2 and 4 will approach the nonfluctuatingcase. 
 When several tubes are connected as a chain, the output signal-to- noise ratio cannot be better than that of the worst stage. For this reason the input stage, especially, must be checked to see if it has an adequately low noise figure; otherwise, it may prevent the entire chain from achieving a sat- isfactory signal-to-noise ratio. For example, a low-level TWT with 0.5-mW RF signal input and 35 dB noise figure will limit signal-to-noise ratio of the am- plifier chain to 74 dB in a 1-MHz bandwidth. 
 I. pp. 174-187, 1959. 
 In some systems, only the sum of the matches is counted and an offset of -M2 is added to the sum. Doppler Correction. In many applications the effect of doppler is negligible over the expanded pulse length, and no doppler correction or compensation is required. 
 RMS of residual deformation of a 25-interferogram comparison for two models. In addition, ground measurements of two leveling points in the test area were collected (the locations of the leveling points are shown in Figure 3a, close to Anlite Bridge). The temporal span of leveling measurement was from June 2014 to February 2015. 
 L. Lichtenberg, B. Marinelli, and S. 
 Conf. HF Radio Systems and Techniques , IEE  Conference Publication no. 474, July 2000. 
 HALF OF A SYMMETRICAL WAVEFORM &IGURE  B   (OWEVER  THE NONSYMMETRICAL WAVEFORM RETAINS SOME OF THE RANGE 
      
 (lJ <::> LL001--- -S!-~ ~ ~ 0.005<::> ~ ~ 0002>..=0 Figure12.7Theoretical fieldstrength (relative tofree-space fieldstrength) asafunction ofthedistance fromthetransmitting antenna. Vertical polarization, II"=h,=100m,k=I,ground conductivity = 10-2mho/m. dielectric constant=4.(Afier B!I"~ows alldAttwood,S cOllrtesy Academic Press.fllc.). 
 GUIDE PHASED ARRAY AND INDEPENDENT RECEIVERS TO ACQUIRE A VOLUMETRIC COVERAGE OF CONVECTIVE STORMS IN n MINUTES  0ULSE COMPRESSION IS NOT USED 4HE RAPID DATA  ACQUISITION SPEED OF THIS SYSTEM HAS THE POTENTIAL TO GIVE NEW INSIGHTS INTO THUNDER 
 MENTS v * !TMOS /CEAN 4ECH   VOL   PP n    $ . -OISSEEV  # - ( 5NAL  (7 * 2USSCHENBERG  AND ,0 ,IGTHART  h)MPROVED POLARIMETRIC  CALIBRATION OF ATMOSPHERIC RADARS v * !TMOS /CEAN 4ECH  VOL   PP n    ! 2YZHKOV AND $ :RNIC  h!SSESSMENT OF RAINFALL MEASUREMENT THAT USES SPECIFIC DIFFERENTIAL  PHASE v * !PPL -ETEOROL   PP n    ' :HANG  * 6IVEKANANDAN  AND % "RANDES  h! METHOD FOR ESTIMATING RAIN RATE AND DROP SIZE  DISTRIBUTION FROM POLARIMETRIC RADAR MEASUREMENTS v  )%%% 4RANS 'EOSCI 2EMOTE 3ENS  VOL    PP n    * 6IVEKANANDAN  ' :HANG  3- %LLIS  $ 2AJOPADHYAYA  AND 3+ !VERY  h2ADAR REFLECTIVITY  CALIBRATION USING DIFFERENTIAL PROPAGATION PHASE MEASUREMENT v  2ADIO 3CI  VOL   PP n TO  n    0 +OLLIAS  " ! !LBRECHT  AND & -ARKS  *R  h7HY -IE  v  "ULL !MER -ETEOR 3OC   VOL     PP n    2 * $OVIAK  6 "RINGI  ! 2YZHKOV  ! :AHRAI  AND $ :RNIC  h#ONSIDERATIONS FOR POLARIMETRIC  UPGRADES TO THE OPERATIONAL 732 
 TO 
 15. Kerr, D. E. 
 11.12. (Reprinted with permission from the AT&T Technical Journal, copyright 1947, AT&T.2) Measured values for a dozen species are listed in Table 11.2. (The spider is an arachnid, not an insect, of course.) The animals were live for the measurements but had been drugged to immobilize them. 
 SQUARED DISTRIBUTION SURVIVAL FUNCTION 0XXTEDT TEDTTX T      AGA AA A 
 Thesenseofthelinearpolarization oftheenergyradiated bythefeedis madethesameastheorientation ofthewiresoftheparabolic reflector. Thefeedinthecenter orthefigureilluminates theparabolic reflector· andthereflected energyisincidentonaplanar mirrorconstructed asatwistreflector. Asmentioned previously atwistreflector reflect~the incident energywitha90°rotation oftheplaneofpolarization. 
 (4.21), except that the power spectrum JYs(f) describing the spectrum  produced by t~e finite time on target is used. The clutter attenuation is  C -s: Ws(f) df  A -J; Ws(f) I H(f) 12 df (4.lS)  where H(f) is the frequency response function of the MTI signal processor. If the antenna  main-beam pattern is approximated by the gaussian shape, the spectrum will also be gaussian. 
 90. Shanks, H. E.: A Geometrical Optics Method of Pattern Synthesis for Linear Arrays, IRE Tra11s .. 
 Radar–77 , Conf. Pub. 155, London, October 25–28, 1977, pp. 
 TO 
 CW AND FREQUENCY-MODULATED RADAR 89  where JO, J 1• J 2, etc= Bessel functions of first kind and order 0, 1, 2, etc .. respectively  D = (f'J//1~) sin 2rr/~R 0/c  R0 = distance to target at time t = 0 (distance that would have been meas­ ured if target were stationary)  c = velocity of propagation  Id= 2t'r .f~/c = doppler frequency shift  1·, = relative velocity of target with respect to radar  ¢0 = phase shift approximately equal to angular distance 4rr.f0 R0/c  <Pm = phase shift approximately equal to 2nfm R0/c  The difference-frequency signal of Eq. (3.16) consists of a doppler-frequency component  of amplitude J 0(D) and a series of cosine waves of frequency fm, ~fm, ~fm, etc. 
 In the presence of a doppler frequency shift, a bank of matched filters is required, with each filter matched to a different fre- quency so as to cover the band of expected doppler frequencies. 70.2 FACTORSAFFECTINGCHOICEOFPULSE COMPRESSION SYSTEM The choice of a pulse compression system is dependent upon the type of waveform selected and the method of generation and processing. The primary factors influencing the selection of a particular waveform are usually the radar requirements of range coverage, doppler coverage, range and doppler sidelobe levels, waveform flexibility, interference rejection, and signal-to-noise ratio (SNR). 
 Ayasli, E. M. Adams, D. 
 4IME 3IGNAL 0ROCESSING  .EW 9ORK 0RENTICE (ALL  )NC    7 +ESTER   4HE $ATA #ONVERSION (ANDBOOK  ,ONDON %LSEVIER.EWNES     2 ( 7ALDEN  h!NALOG 
 The field intensity pat­ tern is the magnitude of Eq. (8.2), or  Ir (0) I = I sin [~~!<'i~2_~in_O] I  'a sin [rr(d/J) sin OJ (8 .. 1)  The pattern has nulls (zeros) when the numerator is zero. 
 If the delay voltage were zero, any output which might appear  from the receiver would be due to the failure of the AGC circuit to regulate completely.  In many applications of AGC the delay voltage is actually zero. This is called undelayed  AGC. 
 Electronically scanned arrays are composed of very many parts and include electronic circuitry to drive the phase shifters or switches that steer the beam. The overall reliability of such arrays can be great; graceful degradation has been claimed, since the failure of as much as 10 percent of the components leads to a loss in gain of only 1 dB. There is, however, a degradation of (low) sidelobes. 
 The output of  the matched filter is then  00  x(TR, fd) = u(~)u*(L + dt (1 1.49) - 00  In this form a positive TR indicates a target beyond the reference delay To, and a positive fd  indicates an incoming targett3 The squared magnitude I z(TR, fd) l2 is called the amhiytriry  function and its plot is the ambiguity diagram.  The ambiguity diagram has been used to assess the properties of the transmitted  waveform as regards its target resolution, measurement accuracy, ambiguity, and response to  clutter.  Properties of the ambiguity diagram. 
 Thisassumption ismadetosimplify the computations. Oneofthemostaccurate methods forobtaining theatmospheric profileof theindexofrefraction iswithanairborne microwave refractometer.40.41Inoneversion,39 two precision microwave transmission cavities areemployed, oneofwhichisopentocollecta sampleoftheatmosphere. Theotherishermetically sealedandactsasareference. 
 68-75, January, 1970.  43. Heidbreder, G. 
 This results in less improvement factor for a two-frequency MTI as  compared with a single-frequency MTI. Note also that the clutter doppler spread of a radar  which actually radiated a carrier frequency !if would be less than that of a radar at carrier  frequency .f~. by the amount 1!,.f!f~. 
 Otherconsiderations includethesizeandweight,high-voltage andX-rayprotection, modulation requirements, andthemethodofcooling.Atransmitter isa majorpartofaradarsystem; hence,itssize,cost,reliability, andmaintainability can significantly affectthesize,cost,reliability, andmaintainability oftheradarsystemofwhichit isapart.Notonlydoesthetransmitter represent asignificant fractionoftheinitialcostofa radarsystem,butitcanoftentakealargeshareoftheoperating costsbecauseoftheprime powerandtheneedsofmaintenance. Theclassical radarrangeequation (Chap.2)showsthat thetransmitter powerdepends onthefourthpoweroftheradarrange.Todoubletherangeof aradar,thepowerhastobeincreased 16-fold.Buyingradarrangewithtransmitter power alonecantherefore hecostly. Thusthercarcmanydiverscrequirements andsystemconstraints thatenterintothe selection anddesignofatransmitter. 
 TIONS OF A FRIENDLY SYSTEM  FORCE  OR COMPLEX TO OBTAIN MAXIMUM ADVANTAGES IN THE AREAS OF INTELLIGENCE DATA RECEPTION  DETECTION  IDENTIFICATION  NAVIGATION  MISSILE GUID 
 VAPOR ABSORPTION LINE AT  '(Z 4HE ONE 
 The linear voltage and power scales in a, b, and c leave much to be desired in showing lower-level pattern details, while d provides good "visibility" of the entire pat- tern. Of course, polar patterns can also be plotted by using decibels in the radial dimension, but lower-level details are compressed near the center of the pattern chart and visibility is very poor. Figure 6.2 shows the reason why rectangular- decibel pattern plots are most often preferred. 
 TIZED PHASE INFORMATION AND CONTROL BITS  FOREMOST OF WHICH IS @ALERT  ARE APPLIED TO THE TELEPHONE LINES VIA A DIGITAL DATA TRANSMITTERv FROM (ANDBOOK FOR .!630!352 3YSTEM  /RIENTATION    COURTESY 53 .AVY      
 D" TIME DELAY RESOLUTION IS MEASURED BETWEEN THE VALUES OF T FOR WHICH    LOG \ SINC"S  \      
 ENCE SIGNAL AND ENCODED DIGITIZED  BY THE !$$!3 ENCODING EQUIPMENT 4HE DIGITAL COMBINER  CONTAINED WITHIN THE !$$!3 ENCODER  RECEIVES THE  +(Z PHASE DATA AND GENERATES AN UNAMBIGUOUS ZENITH ANGLE SOLUTION 4HE COMBINER OUTPUTS ALONG WITH DIGI 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 12.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 well-defined angular spacing. 
 A P-23, pp. 619 622. September, 1975. 
 Rather, many of the detections (contacts) are filtered out in  software using a process called activity control.32,40 The basic idea is to use detection  signal characteristics in connection with a map of the detection activity to reduce the  rate of detections to one that is acceptable for forming tracks. The map is constructed  by counting the unassociated detections (those that do not associate with existing  tracks) at the point in the track processing shown in Figure 7.25. Counts are averaged over many revisits of the radar to achieve statistical signifi - cance. 
 SIBLE TO EXTRACT ACCURATE SEA 
 The beam is one composed of electrons, travelling at  high speed. They can be shifted from their path by  electrostatic or electromagnetic means. If we so shape  our focusing electrodes the shift of the beam from its  non-defliected position can be achieved without any  serious effect on the focusing. 
 DIMENSIONAL WIND  MEASUREMENT THEORY v 2ADIO 3CI  VOL   PP n     ' :HANG AND 2 * $OVIAK  h3PACED 
 F. Bush and F. T. 
 Guinard, N. W., and J.C. Daley: An Experimental Study of a Sea Clutter Model, Proc. 
 P. Hansen, I. D. 
 The reflected energy therefore  will have a polarization perpendicular to the wires of the parabolic reflector and will pass  through with negligible attenuation. The twist reflector can be made relatively broadband. An  attractive feature of this antenna configuration is that the beam can be readily scanned over a  wide angle by mechanical motion of the low inertia planar reflector. 
 Thus the number ofsingle-tuned stages needed inanamplifier of given gain, even formoderately wide bandwidths, becomes prohibitively large. Lacking better tubes, the only alternative liesintheuseofmore effective circuits. Two things are needed: (1)acoupling circuit that will give agreater gain-bandwidth product foragiven tube, and (2)a response-vs.-frequency curve that, when cascaded, does not narrow as rapidly asthat given inEq. 
 TION ANGLES WHERE VEHICLE TRAFFIC AND MANY BIRDS  BATS  AND INSECTS  IS ENCOUNTERED 4HE RADAR TRANSMITS ENERGY USING THE BASIC PATTERN  BUT USES A HIGHER ANGLE BEAM FOR RECEPTION AT SHORTER RANGES  AND THE BASIC ANTENNA PATTERN FOR RECEIVING AT LONGER RANGES &IGURE  SHOWS  UNDERNEATH THE TRANSMITTING FEED HORN  A SECOND RECEIVE 
 I) or type TR. 3160 (Lucero Mk. II), which was used to interrogate the 1.5 m beacon Figure 3.1. 
  $#( &)&&$(#!+/!-. 
 One form of bright display is the direct-view storage  tuhe. 31 It not only operates under ambient light conditions, but it can provide a variable  persistence. In this device, neither the brightness nor the persistence is directly affected by the  short duration of the video signal, or by the characteristic of the viewing-screen phosphor. 
 The traveling-wave lobes tend to disap- pear as the dipole becomes shorter and are closely related to those excited on traveling-wave antennas.RAYLEIGH REGION MIE OR RESONANCE REGIONOPTICAL REGION<r»pher«/1rQ2 . Q/X FIG. 11.4 RCS of a lossy dielectric sphere with n = 2.5 + /0.01. 
 Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  125          Figure 12.17  Spectrum of 1.37  MHz linear Chirp and Gaussian weighting function designed  for 45  dB side lobes.   12.2.2  Linear and Nonlinear Chirp Waveforms   When the classical linear chirp waveform is used in Radar, additional weighting in the fr e- quency or time domain must be added to the matched filtering, as shown in Figure  12.16, in  order to obtain acceptable side lobes [1, 2]. As an example, the spectrum of a 100 µs linear  chirp is shown in Figure 12.17 together with a Gaussian weigh ting filter designed to provide  45 dB side lobes. 
 The block diagram is modified to that shown in Figure 3.28,  with multiple doppler filter banks on each antenna element and PRI delay. Post-Doppler, Beam Space STAP.  The final category results from implement - ing both doppler and spatial transformations prior to STAP processing. 
 129. sensors Article Interferometric DEM-Assisted High Precision Imaging Method for ArcSAR Yanping Wang1, Yang Song1, Yun Lin1,*, Yang Li1, Yuan Zhang1and Wen Hong2 1School of Information Science and Technology, North China University of Technology (NCUT), Beijing 100144, China 2Institute of Electronics, Chinese Academy of Science (IECAS), Beijing 100190, China *Correspondence: ylin@ncut.edu.cn Received: 4 June 2019; Accepted: 28 June 2019; Published: 1 July 2019/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: Ground-based arc-scanning synthetic aperture radar (ArcSAR) is the novel ground-based synthetic aperture radar (GBSAR). It scans 360-degree surrounding scenes by the antenna attached to rotating boom. 
 TIME ADAPTIVE PROCESSING ARE EXPRESSLY DEVELOPED TO IMPROVE CLUTTER CANCELLA 
 Soft clay has the properties of mellow soil, large natural water content, and high compressibility. Under the conditions of constant external load, deformation is related to natural compression and the extravasation of the inner water in the soft soil, combined with external environmental factors (such as rainfall and temperature), thus the deformation of soft clay is characterized as an obvious temporal non-linear variation. In particular, for highways built on soft clay, a single pure empirical mathematical function may not describe the actual dynamic evolution, due to its temporally complicated non-linear characteristics, and a negative impact could be imposed on the accuracy of the obtained measurements and the subsequent displacement prediction. 
 88. Croney. J.: The Reduction of Sea and Rain Clutter in Marine Radars, J. 
   . £Ç°£Ó  2!$!2 (!.$"//+  4HROUGH APPROPRIATE RANGE 
 427-447, February, 1961.  64. Schwan, H. 
 FACTOR #OURTESY OF $R 0ETER ( 3TOCKMANN  ,OCKHEED -ARTIN  -ARITIME AND 3ENSOR 3YSTEMS  3YRACUSE  .9  .   05,3% #/-02%33)/. 2!$!2   n°£x PERFORMANCE IN TERMS OF 3.2 LOSS AND PEAK TIME SIDELOBE LEVEL 43,  THAN THE ,&-  WAVEFORM 4HE 43, LEVEL DOES NOT DEGRADE APPRECIABLY FOR THE ,&- WAVEFORM FOR HIGHER RADIAL VELOCITIES  DEMONSTRATING THE HIGHER DOPPLER TOLERANCE OF ,&-&)'52%     &REQUENCY MODULATION 
 The variation between beam aspect and end-on aspect detection ranges suggest avariation with aspect of radar cross-section (RCS) of 7 –10 dB. Finally, average detection ranges against Lundy Island from the west and the Chivenor training buoy were reported, as shown in table 7.3. It may be noted that the detection range against the Chivenor buoy for ASV Mk. 
  A  AND  @  A  F  TARGET TRACKERS v  )%%% 4RANS !EROSPACE AND %LECTRONIC 3YSTEMS  !%3 
 Poling, A. C.: Tellurometer Manual, U.S. Dept. 
 1200-1201, July, 1959.  64. Crispin. 
 BIT SIGN PLUS  AMPLITUDE  BITS  !$ CONVERTER ARE ASSUMED  AS SHOWN IN &IGURE  4HE TRANSMIT PULSE DURATION IS  MS  RESULTING IN A TRANSMIT PULSE BANDWIDTH OF APPROXIMATELY  -(Z SINCE NO PULSE COMPRESSION IS USED 4HE RMS THERMAL 
 effect on radiated signal, 6.11 exciter, 6.47 filtering, 6.24 to 6.29 front end, 6.10 to 6.14 gain control of, 6.22 to 6.24 instability, 6.20 to 6.21 I/Q channels, 6.31 to 6.35 limiter, 6.29 to 6.31 local oscillator, 6.14 to 6.22 multi-channel, 6.45 to 6.46 noise, 6.4 to 6.5 and tracking accuracy, 9. 42 spurious response, 6.11 to 6.12 STALO, 6.14 to 6.20 upconversion, 6.47 to 6.50 waveform generation, 6.47 to 6.50 Receiver-related ECCM, 24.32 to 24.33 Reentrant structures and cross section, 14.3 Reflectivity, 19.3 Reflectivity factor, Z, 19.4 Reflector antenna analysis, 12.31 to 12.35 applications of, 12.1 to 12.2 architecture, 12.16 to 12.25 array feeds  for, 12.28 to 12.30 basic principles of, 12.3 to 12.15 environmental factors, 12.39 feed blockage, 12.6 to 12.8.     I_14 Reflector antenna ( cont. 
 FERE MULTIPATH INTERFERENCE  )F TWO WAVES ARRIVE AT THE SAME POINT IN PHASE  THEY CONSTRUCTIVELY INTERFERE  AND THE ELECTRIC FIELD STRENGTH IS GREATER THAN EITHER OF THE TWO COMPONENT WAVES TAKEN ALONE )F THE TWO WAVES ARRIVE TOGETHER OUT OF PHASE  THEY DESTRUCTIVELY INTERFERE  AND THE RESULTANT FIELD STRENGTH IS WEAKENED !S THE GEOMETRY OF THE TRANSMITTER AND RECEIVER CHANGE  THE RELATIVE LENGTHS OF THE  DIRECT PATH AND REFLECTED PATH ALSO CHANGE  WHICH RESULTS IN THE DIRECT AND REFLECTED WAVE ARRIVING AT THE RECEIVER IN VARYING AMOUNTS OF PHASE DIFFERENCE 4HE RECEIVED SIG 
 -If thetransmitting antenna were toradiate energy isotropically-that is,uniformly inall directions—the power flow through unit area atadistance Rfrom the antenna could befound bydividing P,the total radiated power, by 4TRZ. Adirective antenna, however, will concentrate the energy in certain directions. The power flow observed atsome distant point will differ bysome factor Gfrom that which would beproduced byanantenna radiating isotropically thesame total power. 
 Mumford: The Effective Noise Temperature of the Sky, Aficrowuve J , vol 3,  pp. 80-84, March, 1960.  53. 
 585–598, September 1976. 20. L. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.62  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 The performance estimation charts that follow come from analyses as described  above. After performing oblique sounding calculations, a range-indexed table of  propagation and noise parameters is compiled. 
 The performance of a reflector without the protection of a radome can also bc degraded  by rain. The effect is small, however, at frequencies below X band. Water impinging on the  antenna feed can have serious effects. 
 Targets such as  satellites and ballistic missiles operate above both the troposphere and the ionosphere. The  effects of the entire atmosphere must be considered in such  case^.'^.^^  12.5 ANOMALOUS PROPAGATION  A decrease in atmospheric index of refraction with increasing altitude, as described in the  previous section, bends the radar rays so as to extend the coverage beyond that expected with  a uniform atmosphere. If the gradient of the index of refraction is strong enough for the rays to  450INTRODUCTION TORADAR SYSTEMS Equations (12.11)havebeenusedattimesasameasure oftheline-of-sight coverage ofa ground-based radarviewingatargetataheighth.Thismayleadtoincorrect resultsinsome casessincetheopticallineofsightdoesnotnecessarily correspond totheradarlineofsight,as explained inSec.12.6. 
 IZED SCANNING MOTION  7NPATH  AND THE OTHER   #P    WHICH IS ADDED TO THE SUM PATTERN AND FED TO THE DELAYED PATH  AS SHOWN IN &IGURE  4HE PROCEDURE WAS DEVELOPED FOR A SING LE 
 The aspect is at grazing incidence. When averages of the cross section are taken  about the port and starboard bow and quarter aspects of a number of ships (omitting the peak  at broadside), a simple empirical expression is obtained for the median (50th percentile) value  of the cross section:  OA . 20 40 60 80 120 140 160  Az~mulh aspect angle (degl  20  m  b 10 A - IBO* Figure 2.19 Same as Fig. 
 SCAN TRACKING.   42!#+).' 2!$!2   °£Ç -ONOPULSE RADAR WAS DEVELOPED TO PROVIDE SIMULTANEOUS OFFSET ANTENNA BEAMS FOR  COMPARISON OF TARGET ECHO AMPLITUDES ON A SINGLE PULSE INDEPENDENT OF ECHO SIGNAL  AMPLITUDE FLUCTUATIONS (OWEVER  FEW MICROWAVE DEVICES AND COMPONENTS WERE INI 
 Hence, in addition to per - forming the basic decomposition described above, and calibrating the receiver chain  for the current waveform, the signal processing stage may be tasked with a number of  signal conditioning operations. Signal conditioning here refers to filtering and scaling  processes aimed at removing contamination and distortion that, if left on the signal,  would degrade the results of the primary processing operations, such as doppler analy - sis, and be more difficult to remove after that primary processing. Typically, there are  (optional) processing algorithms available to remove impulsive noise originating from  lightning, transient echoes from meteors, and field-aligned irregularities in the iono - sphere, strong directional interference, and clutter echoes from beyond the maximum  unambiguous range. 
 Hansen, “A system for performing ultra high resolution backscatter measurements of  splashes,” in Proc. Int. Microwave Theory & Techniques Symp ., Baltimore, 1986. 
 (I) Heavily wooded hills, 20 mi/h wind blowing  (a= 2.3 x 1017); (2) sparsely wooded hills, calm  day (a = 3.9 x 1019); (3} sea echo, windy day  (a= 1.41 x 1016); (4) rain clouds (a= 2.8 x 1015);  (5) chaff (a= l x 1016). (From Barlow,49 Proc.  IRE.)  The clutter spectrum can also be expressed in terms of an rms clutter frequency spread cr,  in hertz or by therms velocity spread <lv in m/s.46 Thus Eq. 
 This  is important in radar application since the receiver sensitivity will be degraded if sufficient  electrons are present during the interpulse period to cause the stray electron-current noise to  exceed receiver noise.  The high-power klystron may also be pulsed with a grid in the electron gun so designed  that the grid does not intercept the electrons.7•8 Such nonintercepting gridded guns can switch  the lieam with low-power modulators. This technique actually uses two closely spaced and  aligned grids. 
 Stillanother advantage oftheCassegrain antenna istheflexibility withwhichdifferent transmitters andreceivers canbesubstituted because of'theavailability oftheantenna feed systematthebackofthereflector ratherthanoutfrontatthenormalfocus.TheHaystack microwave research system,24 forexample, isafullysteerable Cassegrain antenna 120ftin diameter, enclosed bya150-ftdiameter metalspace-frame randome. Itwasdesigned tooper­ ateatfreque.pcies from2to10GHzforradar,radioastronomy, andspacecommunications. Tofacilitate multifunction use,theRFcomponents areinstalled inanumber ofplug-in modules, 8by8by12feetinsize,whichmountdirectly behindtheCassegrain reflector. 
 ,  0LANAR !RRAYS  ! PLANAR ARRAY IS CAPABLE OF STEERING THE BEAM IN TWO DIMEN 
 The  outputs of all the elements are summed via lines of equal length to give a sum output voltage  E0• Element l will be taken as the reference signal with zero phase. The difference in the phase  of the signals in adjacent elements is ijJ = 2n(d/l) sin 0, where O is the direction of the incoming  radiation. It is further assumed that the amplitudes and phases of the signals at each element  are weighted uniformly. 
 FILTER CELL %ACH CLUTTER PATCH CONTRIBUTES CLUTTER POWER AS A  FUNCTION OF THE ANTENNA GAIN IN THE DIRECTION OF THE CLUTTER PATCH AND THE REFLECTIVITY OF THE CLUTTER PATCH 4HE MAIN BEAM ILLUMINATES THE ELLIPTICAL AREA TO THE LEFT OF THE GROUND TRACK 3INCE  THIS AREA LIES ENTIRELY WITHIN THE FILTER AREA  THE MAIN 
 Inthe case ofthe airborne set, severe limits were imposed onweight, size, and similar. 590 EXAMPLES OF RADAR SYSTEM DESIG.V [SEC. 152 factors, and theingenuity ofthedevelopment and design men was taxed tomeet the minimum acceptable radar performance within these limits. 
 Menzel, D. H.: "The Radio Noise Spectrum," Harvard University Press, Cambridge, Mass., 1960  50. Greene, 3. 
 on Geosc. and Remote  Sensing , vol. 38, pp. 
 SOLID 
 Its major limitations are its  poor stability which limits the ability to detect moving targets in clutter, its relatively  modest average power, and its signal cannot be readily modulated for pulse compres - sion. These and others are discussed next. The use of the doppler frequency shift to detect moving targets in the midst of  large clutter echoes requires that the transmitter produce a stable signal with little  extraneous noise. 
 Clampitt, L. L.: Microwave Radar Tubes at Raytheon, Electronic Progress, vol. 17, no. 
 Thisiscalledtherrmode.Thepresence ofNcavitiesinthemagnetron results inN/2possible modesofoperation. EachoftheseN/2modescorresponds toadifferent RF fieldconfiguration madeupofastanding waveofcharge.Allthemodesexcepttherrmodeare degenerate: thatis,theycanoscillate attwodifferent frequencies corresponding toarotation ofthestanding-wave pattern, wherethepositions ofthenodesandantinodes areinterchanged. ThusthereareN-1possible frequencies inwhichthemagnetron canoscillate. 
 Inc.,  Englewood Cliffs, N. J.. 1950. 
 GROUND NOISE CAUSES DEGRADATIONS OF THE 3!2 IMAGE TO AN EXTENT WHERE SHIP AND WAKE CAN NO LONGER BE IDENTIFIED IN THE IMAGE )N THE LITERATURE   SOME CRITICAL ASPECTS  IN  TERMS OF JAMMER RECEIVER SENSITIVITY AND TRANSMITTED POWER  FOR SPOT 
 SAMPLED OUTPUT OF THE RECEIVER IS DOWNCONVERTED TO BASEBAND $#  VIA A DIGITAL PRODUCT DETECTOR $0$   3UPERIOR )1 IMAGE REJECTION IS AN ADVANTAGE OF A $0$ 4HE ) AND 1 SIGNALS ARE PASSED THROUGH THE DIGITAL PORTION OF THE PULSE MATCHED  FILTER 4HE COMBINATION OF THE  )& MATCHED FILTER AND THE DIGITA L MATCHED FILTER FORM THE  RECEIVERS SINGLE 
 3.19a) will receive a doppler-shifted echo signal from the ground. The shift in  Figure 3.19 (o) Aircraft with single  doppler navigation antenna beam at an  angle y to the horizontal; (b) aircraft  employing four doppler-navigation  beams to obtain vector velocity.  92INTRODUCTION TORADAR SYSTEMS techniques canbesimilar. 
 4.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 Pulse Doppler Radar* John P . 
 Toavoiddegradation oftheSARduetoangular motions, theantenna mustbestabilized.usRollandpitchanglescanbestabilized bymeans ofgyroscopes. Yawanglecanbecompensated byreference toagyroscope orby..clutter-lock" inwhichtheantenna position isadjusted soastomaintain asymmetrical doppler spectrum aboutzerofrequency. Atmospheric'turbulence aswellasdeliberate maneuvers resultintheaircrafttrajectory. 
 EDGE FORMULA  ALSO GIVEN IN 4ABLE  4HESE UNDULATING PLATE PATTERNS FOLLOW A SIN  XX VARIATION QUITE CLOSELY FOR ASPECT  ANGLES OUT TO ABOUT  n "EYOND THAT ANGLE  THE TWO PATTERNS DIFFER BY PROGRESSIVELY  WIDER MARGINS 4HE SIN  XX BEHAVIOR IS CHARACTERISTIC OF A UNIFORMLY ILLUMINATED APER 
 12 dj is a small perturbation e.g. 0.1 …0.3 yielding visibility > 96% Vblind is a function of f describing eclipsing and straddling Rblind is a function of r describing eclipsing and straddling C3 is a constant representing the remainder of the range equation f is frequency, r is range, mod is modulo the first variable by the second Range-Gated High PRF.  Range-gated high PRF (RGHPRF) performance is  dramatically better for detection of higher speed closing targets.44,54,55,70 (Range gates  are often smaller than range resolution cells or bins). 
 Duct formation by thunderstorms may not tc as  frequent as other ducting mechanisms, but it is of importance since it may be used as a means  of detecting the presence of a storm. An operator carefully watching a radar display can dctcct  the presence of a storm by the sudden increase in the number and range of ground targets. The  conditions appropriate to thet formation'of a thunderstorm duct are short-lived and have a  time duration of the order of'perhaps 30 min to 1 h. 
 These errors can becompletely eliminated by use ofamore complicated amplifier ofgain greater than 1,the excess gain compensating forthe drop across Cl. Analternative istoadd tothe sawtooth acompensating voltage which, should beapproximate] yproportional tothe integral ofthe sawtooth.. SEC. 
 With a GaN epitaxial layer processed on a SiC  substrate, the current state-of-the-art for transistor performance is defined on several  fronts in the semiconductor industry by the following performances: (1) pulsed power- added-efficiency (PAE) of 68% at 30 V and 10 GHz on a 1.25 mm FET, and CW  power of 5 W at 30 V and 10 GHz on a single 1.25 mm transistor;25 (2) power density  of 8.6 W/mm at 40 GHz;26 (3) less than 0.2 dB power degradation after 15,000 hours   RF operation at 28 V with channel temperatures of 150 °C.27 Power-added efficiency  is a circuit designer’s term and is defined by  PAE = (PO − PI)/PDC (11.3) where PO is the RF power output, PI is the RF power input, and PDC is the total   dc power input. Figure 11.11 and Figure 11.12 illustrate the advantages of GaN at 10 GHz when  compared with the physical geometry of an identically sized GaAs PHEMT transistor.  GaAs Circuit FET Behavioral Model   10 GHz, 1mm, 7V, 25C 010203040506070 −8−4 0 4 8 12 16 20 24 RF Drive (dBm)Po(dBm), PAE(%) 02468101214 Gain (dB )Po (Power Output) PAE (Efficiency ) Gn (Gain) FIGURE 11.11  Typical 10-GHz performance curves for a 1 mm  periphery GaAs PHEMT FET operating at +7 V using a CW (100%  duty) waveform ch11.indd   16 12/17/07   2:25:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 sourcc of largc Kf; powcr. -1'liis li~iiitcd tlic dcvcloprilcrlt of tlic  early radars to tlie VffF arid the lower UHF bands. These tubes were triodes or tetrodes  dcsigticd to 11iiriinii7e tlie transit-time effects and other problems of operating at VHF arid  UHF." Tlie poteritial applied to the control grid of the tube acts as a gate, or valve, to control  the number of electrons traveling from the cathode to the anode, or plate. 
 9. pp. 111-121. 
 ¤ ¦¥³ µ´  P    WHERE   "FF       LN   SS    4HE EARLY EXPERIMENTAL RESULTS THAT LED TO THE GENERAL ADOPTION OF THE GAUSSIAN MODEL  WERE OBTAINED WITH RADAR EQUIPMENT OF LIMITED STABILITY  AND THE SPECTRAL SHAPE WAS  SOMETIMES DERIVED FROM VIDEO SPECTRA COMPUTED USING SQUARE 
 24,Sec. 8.2. Our interest just now isinthe position ofthe minimum ofeach curve that isseen tolienear @=1.2/7. 
 PULSE  DISPLACEMENT )N THE OTHER COMPENSATED CASE  THE OPTIMUM GAIN RATIO  K IS APPROXIMATED  BY THE LINEAR FUNCTION OF INTERPULSE PLATFORM MOTION K6 X ! BLOCK DIAGRAM OF THE DOUBLE 
 VERTICAL GEOMAGNETIC FIELD LINES PROVIDE A PATHWAY  FOR CHARGED PARTICLES AND DISTURBANCES OF SOLAR AND MAGNETOSPHERIC ORIGIN TO REACH  IONOSPHERIC HEIGHTS AND CONTRIBUTE TO IONIZATION PROCESSES AND PLASMA TRANSPORT 4HE  BEST KNOWN PHENOMENA HERE ARE THE AURORAE  WHICH ARE CONCENTRATED IN OVALS POLE 
 This affects  the precision obtained when displaying radar-derived data, which can differ when  switching between the various radar stabilization modes used on CMR. For instance,  in order to facilitate both collision avoidance and position fixing activities, shipborne  radar displays have always had two particular stabilization modes: Head-up and North- up. The “up” direction refers to the vertical ( y-axis) direction of the radar display;  “Head” refers to the ship’s heading. 
 As with clutter due  to birds, sensitivity time control (STC) can reduce the adverse effects of clutter due to insects.  Clear-air turbulence. Some types of angel echoes which are nonpoint targets are attribtrted to  atmospheric effects rather than to birds or insects. 
 This architecture requires less mass and  offers greater efficiency than alternatives, while capturing all of the potential informa - tion in the backscattered field. An antenna comprised of two linear arrays (such as H and V) will radiate a circularly  polarized field if the sets of elements are driven simultaneously and 90 ° out of phase,  as shown in Figure 18.17. In practice, the amplitude weighting and relative phasing  of the arrays will seldom be perfect. 
 Third, the solutions for some objects may contain spurious resonances that do not actually exist, thereby reducing the confidence one may have in applying the method to arbi- trary structures. Figure 11.23 traces the broadside RCS of a perfectly conducting cube com- puted by means of the method of moments. Spurious resonances were sup- pressed in the computations by forcing the normal surface component of the mag- netic field to zero. 
 The space between pulses must be  larger than the intended swath width. For example, in certain modes RADARSAT-1  generates seven pulses “in flight” simultaneously. At the beginning of such a data col - lection, backscatter from the intended scene would arrive only after the seventh pulse  had been transmitted. 
 (b) Effect of blind phase in the I channel,  and (c) in the Q channel.  120INTRODUCTION TORADAR SYSTEMS wordsarestoredinadigitalmemory foronepulserepetition periodandarethensuhtracted fromthedigitalwordsofthenextsweep.Thedigitaloutputsofthe[andQchannels are combined bytakingthesquarerootof[2+Q2.Analternative methodofcombining, whichis adequate formostcases,istotakeIII+IQI.Thecombined outputisthenconverted toan analogsignalbythedigital-to-analog (01A)converter. Theunipolar videooutputisthen readytobedisplayed. 
 W. Biggs: Radar Scatterometer Discrimination  of Sea-Ice Types, IEEE Trans., vol. GE-15, pp. 
 CORRELATION   %S T S T 2 T T A J RT T;      =      EXP;       
 50. D. A. 
 In Fig. 4.5, the coherent reference is supplied by at1  oscillator called the c.ollo, which stands for coherent oscillator. The coho is a stable oscillator  whose frequency is the same as the intermediate frequency used in the receiver. 
 46 BROADCAST TRANSMIT 
 Therefore, the tracking bandwidth  stlould be narrow to reduce the effects of noise or jitter, reject unwanted spectral components  such as the conical-scan frequency or engine modulation, and to provide a smoothed output of  the measurement. On the other hand, a wide tracking bandwidth is required to accurately  follow, with minimum lag, rapid changes in the target trajectory or in the vehicle  carrying the radar antenna. That is, a wide bandwidth is required for following changes in the  target trajectory and a narrow bandwidth for sensitivity. 
 4IME !DAPTIVE 0ROCESSING FOR !IRBORNE 2ADAR   4ECHNICAL 2EPORT   ,EXINGTON   -! ,INCOLN ,ABORATORY  -ASSACHUSETTS )NSTITUTE OF 4ECHNOLOGY    * 'UERCI  3PACE 
 (The dis play of weather clutter is of importance  to the air traflic controller to avoid directing aircraft to areas of severe weather. The display  of land clutter is also of importance in some applications so as to provide reference landmarks.)  In principle. availability of color allows an intensity-modulated CRT, which is normally of  limited dynamic range, to display target amplitude information by color coding the target blip  according to the magnitude of the target cross section. 
 SPEED OPTICAL PROCESSOR TO SUPPORT THE TWO 
 Skolnik, G. Linde, and K. Meads, “Senrad: An advanced wideband air surveillance radar,”  IEEE Trans ., vol. 
 Zrnic, “Rain Rate estimation from differential polarization measure - ments,” J. Atmos. Ocean. 
 86. Kalafus. R. 
 ENDED WAVEGUIDES OR SMALL HORNS   AND PRINTED 
 4. J. Curlander and R. 
 Figure 12.29  Compressed output as in Figure 12.28 but with 10 kHz Doppler shift.   12.2.6  Results   The design process of low -loss, low -side lobe, non- linear chirp pulse- compression systems,  along with considerations for its practical implementation as part of a digital si gnal processing  system, needs to include at least the fo llowing:  Determine the necessary and achievable rise - and fall- times of the transmi tted  waveform, which will meet sp ectrum control requirements.   Develop a signal design, which achieves the desired spectral shaping to minimize  processing losses, while minimizing spectral ripple. 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°ÎÎ !S SEEN IN &IGURE   THE SELECTION OF  1TK  AND THUS  FTRACK ALLOWS ONE TO UNIQUELY  DETERMINE THE STEADY 
 TION 3ECTION   7ITH RANGE GATING  THE RANGE MEASUREMENT ACCURACY IS ON THE ORDER OF THE RANGE GATE SIZE  M MS   BUT THIS CAN BE IMPROVED TO A FRACTION OF THE GATE  WIDTH BY AMPLITUDE CENTROIDING 4IMELINE  $EFINITIONS  0ULSE DOPPLER RADAR WORKS ON SEVERAL DIFFERENT TIME  SCALES 6ARIOUS ORGANIZATIONS HAVE THEIR OWN NOMENCLATURE FOR TIME 
 A limited tuning range, of the order of 1 percent, can be obtained by a screw inserted in  the side of one of the resonator holes. This type of adjustment is useful when the normal scatter  of frequencies expected of untuned magnetrons requires the frequency to be fixed to a specified  value.  In frequency-agile radar systems, the magnetron frequency might be changed pulse-to-  pulse in such a manner that the entire tuning range is covered. 
 If em is made 40°,  the loss is 2.75 dB. In the limit of large Om and small 00, the loss approaches a maximum of  3 dB.  Shaped beams and STC. 
 n 
 OBSERVED BOUNDARY  LAYER CONVERGENCE LINES v -ON 7EATHER 2EV  VOL   PP n    4 7 7ECKWERTH  # 2 0ETTET  & &ABRY  3 * 0ARK  - !  ,E-ONE  AND * 7 7ILSON  h2ADAR  REFRACTIVITY RETRIEVAL 6ALIDATION AND APPLICATION TO SHORT 
 Whereas, inprinciple, the operators ofsuch a specialized radar asablind-bombing device could behighly trained (though, inpoint offact, few were, inthe war), the operators ofthis navigational setwere not primarily concerned withlearning tooperate itproperly. Itsown simplicity had tobegreat enough sothat its operation was nomore difficult tomaster than that, forexample, ofthe radio compass. 15.13. 
 ¤ ¦¥³ µ´ ¯D! DFD        4HIS IS AN INTEGRAL IN WHICH THE AREA ELEMENT BETWEEN  FD AND FD   DFD IS EXPRESSED  IN TERMS OF COORDINATES ALONG AND NORMAL TO THE ISODOPS 3UCH COORDINATES MUST BE  ESTABLISHED FOR EACH PARTICULAR CASE &IGURE  SHOWS THE GEOMETRY FOR HORIZONTAL TRAVEL 4HE COORDINATE  W  IS ALONG THE  ISODOP  AND G  IS NORMAL TO IT 7E CAN EXPRESS %Q  IN TERMS OF THESE COORDINATES AS   7FD DF0'D 2RD DT § ©¨¶ ¸·§ ©¨¶ ¸·HL PSX   STRIPP¯   .OTE THAT  0T  THE TRANSMITTED POWER  IS NON 
 Rlake. L. V.: Ray fleiglit Computation for a Continuous Nonlinear Atmospheric Refractive-Index  Profile. 
 Operates in short and long range modes   • Range  Maximum: 200 nmMinimum:  2 nm • Target RCS: 1 sq. m.• Transmitter Frequency:  402.5 to 447.5 MHz • Pulse width: 60 s• Peak power: 200 to 255 kW• Staggered PRF: 257 Hz (ave)• Non-staggered PRF: 300 Hz•A n t e n n a Parabolic reflectorGain: 21 dBHorizontal SLL:  27 dBVertical SLL: 19 dB HPBW: 11 by 19 degrees • Receiver 10 channels spaced 5 MHzNoise figure: 4.2 IF frequency: 30  MHzPCR: 60:1Correlation gain: 18 dB MDS: −115 dBm MTI improvement factor: 54 dB. 
 Of  course, the whole system could be reversed. The mobile  station could initiate pulses and measure the time of the  ‘interrogated’ pulses from fixed ground responder  stations. Whichever way round the system is worked,  a transmitter has to be carried by the mobile station. 
 46-49, October, 1973.  LU. Kummer, W. 
 "AND RADAR SCATTEROM 
 ON AND ARE PLACED  SIDE 
 I <l B. 7 s)  Typically the number of taps used in a cell-averaging CF AR might vary from 16 to 20.  The CFAR may be thought of as using the outputs of the sampled cells to estimate the  unknown amplitude of the background noise or clutter. 
 POWER KLYSTRON TUBE USED IN THE ORIGINAL "ALLISTIC -ISSILE %ARLY 7ARNING 3YSTEM  HAD A DEMONSTRATED LIFE IN EXCESS OF   HOURS 3YMONS REPORTS THAT ONE OF THE  "-%73 TUBES THAT HE DESIGNED WAS STILL OPERATING AFTER   HOURS WHEN THE RADAR IN 'REENLAND WAS REPLACED BY THE SOLID 
 BIT  TUNING WORD IS ACTUALLY A PHASE INCREMENT THAT DETERMINES THE FREQUENCY OF THE SINE WAVE OUTPUT 4HE PHASE INCREMENT IS EXPRESSED IN A FORMAT CALLED "INARY !NGLE -EASUREMENT "!-   IN WHICH THE MOST SIGNIFICANT BIT -3"  OF THE WORD REPRE 
 However, the Stolt interpolation needs huge computation. Since the multi-angle SAR imaging system adopts the method of multi-beamforming, the beam squint angle is more than 20◦, and the RMA algorithm can process the data of the squint SAR. It can focus the whole scene by interpolation. 
 Remote Sens. Lett. 2018 ,15, 1575–1579. 
 330 INTRODUCTION TO RADAR SYSTEMS  arranged on the surface of a sphere, the plane of polarization changes with the scan angle.  With circular polarization, however, there is no change with scan.  A conventional array with four faces can track four times the number of targets as a dome  antenna (which operates with a single planar array for I~en~ispherical coverage), assurning thc  traffic is distributed uniformly. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 The curves marked 45, 15, and 0 ° give the RCS as the target is rotated to these  angles in the plane that contains the electric vector. The little sketches give, at the left,  the body shape, and then the RCS patterns at nominal 1/2 wavelength, 1 wavelength,  and 3/2 wavelength, in order to help visualize how the RCS will change as the aspect  angle is varied. 
 Anonymous: Moving Target Radar Using Storage Tubes, Electronics, vol. 34, no. 33, pp. 
 OF 
 W.: "Statistical Theory of Signal Detection," Pergamon Press, New York. 1960.  8. 
 Also, the clutter conditions can be less variable because of the  restricted geographical area of operation, and there are no degradations in the accu - racy of the displayed radar image in having to compensate for a ship’s heading with  compass input. In particular, target tracking is performed from a stable and static plat - form. However, it is generally necessary to track many more targets than is required  on a shipborne radar, and normally VTS has fully automatic plot extraction and track  initiation. 
 After simple mathematical manipulations the solution of the integral can be written as ˆS(k,p)=⎭summationdisplay g∈G⎭tildewideag[tkp−tg(p)]·ΔF·exp⎭bracketleftBig j2π[tkp−tg(p)]·fc⎭bracketrightBig ·sin⎭parenleftBig π[tkp−tg(p)]·ΔF⎭parenrightBig π[tkp−tg(p)]·ΔF(9) Thus, the range compressed ISAR signal is a time displaced copy of a sinc function deﬁning the position of g-th scattering point from the space object, the asteroid. In Figure 5, a range compressed signal with time delay t1=0.5μsis presented. In Figure 6, three range compressed signals RCS1, RCS2, RCS3 and their sum RCS, is depicted with the following parameters: microburst time width 2 μs, frequency band width ΔF=100 MHz, signals’ time delays: t1=0.5μs,t2=0.515μs,t3=0.52μs, and amplitudes: a1=1.2, a2=1.8, a3=1.2. 
 SURVEILLANCE RADARS 4HE !IR 2OUTE 3URVEILLANCE 2ADAR !232  USED FOR LONG RANGE AIR 
 475. 476 THERECEIVING SYSTEM—INDICATORS [SEC. 13.1 Inelectrostatically focused tubes a“focus electrode” (first anode) between thesecond grid and thehigh voltage anode ismaintained atan intermediate potential. 
 513-520, July 1983. 20. Hanle, E.: Survey of Bistatic and Multistatic Radar, Proc. 
 ALARM RATE 3INCE RETURNS FROM LAND CLUTTER SCATTERERS USUALLY ARE SPATIALLY FIXED AND  THEREFORE   APPEAR AT THE SAME RANGE AND BEARING FROM SCAN TO SCAN  IT HAS LONG BEEN RECOGNIZED THAT A SUITABLE MEMORY CIRCUIT COULD BE USED TO STORE THE CLUTTER RESIDUES AND REMOVE THEM FROM THE OUTPUT RESIDUE ON SUBSEQUENT SCANS BY EITHER SUBTRACTION OR GAIN NOR 
 STATE POWER AMPLI 
 3.10b. The modulation need not necessarily be triangular; it can be  sawtooth, sinusoidal, or some other shape. The resulting beat frequency as a function of tinle is ""  shown in Fig. 
  
   
 13.20 bythesame azimuth voltage. The horizontal sweep isunmodulated but arranged topermit delay indiscrete steps. Height isread from an engraved scale asexplained inSec. 
 IfOisconsiderably 1The factthat thewaves arrive atBfrom slightly different directions, aswellas theeffect oftheslightly unequal path lengths upon therelative intensity, need notbe taken into account solong asR>>h,>>A. ‘This useoftheterms “horizontal” and “vertical” polarization, though not meticulous, iscommon radar practice, andcauses noconfusion when thedirections of propagation make small angles with thehorizontal, Gfcourse theelectric vector ofavertically polarized wave traveling from AtoMisnotprecisely vertical.. SEC. 
 Hansen (ed.), Academic Press, N.Y., 1966, chap. 2.  77. 
 0ALMER DROP 
 vanKasteren, Ground-based X-band Radar Backscatter  Measurements of Wheat, Barley and Oats , Wageningen Netherlands: Center for Agrobiological  Research, 1989. 12. T. 
   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°x AT EACH ELEMENT MAY RESULT IN SITUATIONS WHERE A SOLUTION DOES NOT EXIST !N EXAMPLE  OF A DETERMINISTIC ANTENNA PATTERN WITH AND WITHOUT NULLING IS SHOWN IN &IGURE   4HE SOLID LINE IN &IGURE  SHOWS A DETERMINISTIC ANTENNA PATTERN AT BROADSIDE FOR A  
 BAND RADAR  
 Figure 12.11  Sea target scena rio and threshold, processed with the CA -CFAR (L = 120, α =  1, β = 53).  . Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  121         Figure 12.12  Sea target scenario and threshold, processed with CAOS -CFAR (A = 30, L= 4,  r = 13, α = 1, β = 35). 
 VENTIONAL &OURIER  BEAMFORMING 7HEN ADAPTIVE PROCESSING TECHNIQUES ARE BEING  EMPLOYED  IT IS ALSO IMPORTANT THAT THE EFFECTIVE LOOK DIRECTION MATCHES THE ARRAY STEER 
 TARGET RANGE VARIATION GENERATES A PHASE TIME 
 TER AND RECEIVER 4HE ROW TRANSMITTERS AND RECEIVERS ARE SIMILAR FOR EACH ROW 4HEY PERFORM ALL THE 2& FUNCTIONS  INCLUDING 2& POWER GENERATION  PHASE SHIFTING TO STEER THE ANTENNA BEAM IN ELEVATION  AND RECEIVE PREAMPLIFICATION TO PROVIDE A LOW 
 PULSE RADARS IS DEPENDENT UPON FEED DESIGN AND IS TYPICALLY  FOR A GOOD MODERN FOUR 
 61-A–61-M.  68. S. 
 The simulation parameters are illustrated in Table 1.   (a) ( b)    (c) ( d)  $]LPXWK GHJ UDQJH .P         $]LPXWK GHJ UDQJH .P         $]LPXWK GHJ UDQJH .P         $]LPXWK GHJ 5DQJH .P         Figure 6. Simulation results in the case of SNR =10 dB; ( a) FFT algorithm; ( b) Relax algorithm; ( c) APES algorithm; ( d) KA-DBS algorithm. 
 Any use is subject to the Terms of Use as given at the website. Meteorological Radar.  METEOROLOGICAL RADAR  19.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 and the product FNyq Ra is simply  F Rc Nyq a=4 (19.22) Since the doppler shift f and the target radial velocity v are linearly related, the  unambiguous velocity is related to the Nyquist frequency by  V Fa=λ 2Nyq (19.23) It follows that the product of unambiguous velocity and unambiguous range is  V Rc a a=λ 8 (19.24) For constant PRF radars, this product is maximized by maximizing l, the transmit - ted wavelength. Thus, using longer wavelengths allows optimizing the PRF by trad - ing unambiguous range for unambiguous velocity. 
 10.2.  The detectability of a target echo on a CRT display depends on such factors as the size  and brightness of the CRT spot, the noise background, pulse repetition frequency, antenna  rotation rate, type of phosphor, and its decay characteristics, the size of the display, and the  color and intensity of the ambient illumination. The effect of most of these factors has been  determined empirically. 
 They can take several different forms and have been attributed to various  causes. There are two general classes of angel echoes: dot angels, which arc point targets due to  birds and insects, and distributed angels, which have substantial horizontal or vatical extent  and are due to inhomogeneities of the refractive index of the atmosphere. Birds and insects in  substantial number can also appear as distributed angels, and can have a degrading effect on  radar. 
 Sir~ce the problem of tnultipath errors occurs for antenna beams whicll illuminate the  surface. one approach is to use three elevation bearns. The lowest beam is made as narrow as  practical in elevation. 
 Bean. 13. R.. 
 10(,. Farth-hased Flectronics, /:lcctronics. vol. 
 FALSE 
 The ionospheric sounder, an important adjunct for HF (short  wave) communications, is a radar. Remote sensing with radar is also concerned with  Earth resources, which includes the measurement and mapping of sea conditions, water  resources, ice cover, agriculture, forestry conditions, geological formations, and environ­ mental pollution. The platforms for such radars include sateJiites as well as aircraft. 
 I EEE Cot!fi.retrcc Record 1976 Itttertrational Corferetrce on Acoustics. Specclt.  crtrd .'iigt~ctl I'i.oc.ersiirq, Ap. 
 SOURCE ECHOUSUALLY ITS PULSE IS DELAYED TO SEPARATE IT FROM THE TARGET ECHOAND WITH HIGH SIGNAL 
 ENCES BETWEEN -9 AND &9 ICE ARE SMALL EVEN IN WINTER 4HIS MEANS THAT IMAGING RADARS CAN EASILY DISTINGUISH ICE TYPES BY INTENSITY ALONE AT THE HIGHER FREQUENCIES IN WINTER BUT NOT IN SUMMER 4HIS FACT IS THE BASIS FOR OPERATIONAL ICE 
 This  function can be obtained with a more sophisticated filter consisting of a parallel combination  of integrator and subtractor. 83 The integrator is a narrow-band filter that averages the order of  ten range-resolution cells to establish the background level. A receiver implemented in this  manner has been called a log-CF AR.• The· term LOG/CF AR has been applied to the cell­ averaging CF AR which· is preceded I by :a logarithmic detector. 
 BASED SCATTEROMETER MAY HAVE ONLY  
 Too high a level  of noise into the A/D converter will degrade the available dynamic range; too low  a level will degrade the overall system noise floor. Sufficient total noise should be  applied to the A/D converter input to randomize or “whiten” the quantization noise.  ch06.indd   38 12/17/07   2:03:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 SIBLY ALSO TO TRANSMIT  ON MORE THAN ONE POLARIZATION )N GENERAL TERMS  THERE ARE FOUR OPTIONS AVAILABLE FOR POLARIMETRIC DIVERSITY IN A  SPACE 
 The Supersonic Delay Line.—The principal elements ofa delay line arethetransmission medium and theelectromechanical trans- ducers. Because ofthebandwidth required, MTI delay lines have been FIG. 16.31.—Circuit ofabalanced detector, operated with amplitude-modulated carrier frequencies inthe region of 15Me/see. 
 RESISTANCE BASE REGIONS UNDER THE EMITTER REGION  CAUSING MOST OF THE CURRENT CARRIED IN THE DEVICE TO BE CROWDED ALONG THE PERIPHERY OF THE EMITTER 4HUS  IN ORDER TO MAXIMIZE THE CURRENT 
 For example, a 1 dB change in the threshold can result in three orders of magni-  tude cnange in the false alarm probability (Fig. 2.5). It does not takc much .if a drift in the  receiver gain, a change in receiver noise, or the presence of external noise or clutter echoes to  inundate the radar display with extraneous responses. 
 Even though a separate radar is employed to measurejarget height,  the combined cost of the 2D air-surveillance radar and the nodding-beam height finder can be  iess than the cost of a comparable single 3D radar. (It is not always true that two radars cost  more, are more complex, or occupy more volume than a "single" radar designed to do the  same job.) Another advantage of the separate nodding-beam height finder in military applica-  tions is that it generally operates at a higher frequency (S or C bands are common choices)  than does the 2D air-surveillance radar. This increases the ECCM capability of the system  since a jammer must radiate in both radar bands simultaneously to deny the location of air-  craft targets. 
 6ARYING 7EIGHTS  4HE IMPROVEMENT FACTOR LIMITATION CAUSED BY PULSE 
 and Q.Z. analyzed the data; Z.D. contributed reagents/materials/analysis tools; L.Y. 
 For reasons similar tothose used incon- nection with thebeating oscillators, this quantity should not exceed tin cycle from pulse topulse. Hence wegetfortheallowed rate ofdrift, in thesame way asbefore, (ifm 1. .— dt100Tr”(4) For T=1(130 ~sec and r=1psec, the rate is10Mc/sec2, which is500 times thepermissible rate forthebeating oscillators. 
 The latter can be achieved either by resistively coating the antenna or by constructing  the antenna from a material such as Nichrome, which has a defined loss per unit area.  In this case, the antenna radiates in a completely different way as the applied charge  becomes spread over the entire element length, and hence, the centers of radiation are  distributed along the length of the antenna. Typical radiated field patterns for a resis - tively loaded dipole are shown in Figure 21.18. 
 Point scatterer image, contour plot, and range and azimuth cuts. Figure 10. B-SAR algorithm. 
 Eandηare signiﬁcant rheological parameters, which are treated as unknown parameters in Equation (3). Finally, trepresents the total time span of strain occurrence. Figure 1. 
 BAND ARRAY THAT REQUIRES SCANNING TO LARGE ANGLES  THE SPACING BETWEEN RADIAT 
 One further advantage of pulse-to-pulse staggering is that it may permit  eliminating the use of feedback in the cancelers (used to narrow the blind-speed  notches), which eliminates the transient settling problem of the feedback filters. The optimum choice of the stagger ratio depends on the velocity range over  which there must be no blind speeds and on the permissible depth of the first null FIGURE 2.38  Shaped-velocity-response feedforward cancelers compared with three-pulse  feedback canceler. See text for five-pulse canceler parameters. 
 Bogle. and I). D. 
 In practice, therefore, the threshold level  would probably be adjusted slightly above that computed by Eq. (2.26), so that instabilities  which lower the threshold slightly will not cause a flood of false alarms.  If the recdver were turned off (gated) for a fraction of time (as in a tracking radar with a  servo-controlled range gate or a radar which turns off the receiver during the time of transmis­ sion), the false-alarm probability will be increased by the fraction of time the receiver is not  operative assuming that the average false-alarm time remains the same. 
 UP OPERATIONS AND ALSO FOR EARLY DETECTION OF SPILLS FROM OIL RIG OPERATIONS )T HAS BEEN PROPOSED  THAT ADDITIONAL PROCESSING OF THE CROSS 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 6.38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 input signal frequency and amplitude. 
 Processing Time The description of the time processing required by the proposed approach to obtain the focused image is reported in Table 4with respect to the original size of the raw data matrices. The experiments have been conducted on a desktop pc equipped by an Intel Core i7 Processor with clock speed of 3.4 GHz and a total number of four cores, and a memory of 16 GB. T able 4. 
 +U n -ODERATEn(IGH -ILSTAR 5(&  +U  
 WATER CONTENT  FOR SNOW AT SEVERAL FREQUENCIES .OTE THE EXTREME VARIATION OF THE  +A BAND AS THE SUN STARTS TO MELT THE SURFACE  AFTER 7 ( 3TILES AND  & 4 5LABY . £È°{È  2!$!2 (!.$"//+  0ROGRAMS TO LEARN MICROWAVE PROPERTIES OF SEA ICE HAVE BEEN NUMEROUS BECAUSE  OF THE IMPORTANCE OF ARCTIC OPERATIONS AND METEOROLOGY -ICROWAVE REMOTE SENSING  IS NECESSARY TO MONITOR ICE PROPERTIES IN THE ARCTIC OWING TO THE LONG WINTER NIGHT  FREQUENT CLOUD COVER  AND INACCESSIBILITY £È°nÊÊ *" , 
 GAIN PRODUCTS  0 AV'4 '2 u 2ECEIVING APERTURES  WAVEFORM BANDWIDTHS  AND COHERENT INTEGRATION TIMES SHOULD PROVIDE ENOUGH SAMPLES AND HIGH ENOUGH SAMPLING RATES TO RESOLVE UNAMBIGUOUSLY DISTINCT FEATURES OF THE CLUTTER SPECTRUM WHERE SUCH RESOLUTION IMPACTS ON TARGET DETECTABILITY OR THE EXTRACTION OF IMPORTANT INFORMATION u 4HE WINDOW FUNCTIONS USED TO CONTROL LEAKAGE DURING CONVENTIONAL SPECTRUM ANALY 
 It is not necessarily a desirable condition since it cannot be relied upon. It can degrade the  performance of MTI radar by extending the range at which ground clutter is seen. ·  The presence of the earth's surface not only restricts the line of sight, but it can cause  major modification of the .coverage within the line of sight by breaking up the antenna  elevation pattern into many lobes. 
 TATION COULD BE USED TO HANDLE MULTIPLE WAVEFORM TYPES !NALOG PRODUCT DETECTORS USED TO EXTRACT  ) AND 1 BASEBAND COMPONENTS HAVE BEEN  REPLACED IN MANY SYSTEMS BY DIGITAL DOWN 
 200 201  Visihility factor. for clutter, 130 INDEX 581  VSWR, and isolation in CW radar, 72  Wave-interference radar, 554  Weather clutter, 498-507  Weather effects, on radomes, 269-270  Weather fix, 507  Weibull probability density function:  land clutter, 496  sea clutter, 480  Weighting, for time sidelobes, 426  Weinstock cross section models, 50  Whitening filter, 375  Wing-beat frequency, bird, 509  Within-pulse scanning, 314-316  by frequency scanning, 302-303  in 3D radar, 545  Wrap-up factor, 299  X-ray hazard, 466  Z, radar reflectivity factor, 500-501  Zero-crossings detector, 384-385  Zoning of lenses, 249, 251 . 
 This, however, is not a  complete measure of the sensitivity of a receiver with a mixer front-end. The overall noise­ figure depends not only on the mixer stage, but also on the noise figure of the IF stage and the  mixer conversion loss. It may be determined from the expression for the noise figure of two  networks in cascade [Eq. 
 8, 1979. 44. D. 
 Long and D. B. Trizna, “Mapping of North Atlantic winds by HF radar sea backscatter  interpretation,” IEEE Trans. 
 7.8 only the phase error was  considered. In an array, however, other factors may enter to cause distortion of the radiation  pattern. These include errors in the amplitude as well as the phase of the current al the  individual elements of the array, missing or inoperative elements, rotation or translation of an  element from its correct position, and variations in the individual element patterns. 
 A. Farina and F. A. 
 K. Barton, “The low-angle tracking problem,” presented at IEE Int. Radar Conf ., London,   October 23–25, 1973. 
 Section 22.4 concentrates on the technology, and Section 22.5 looks at  target tracking. Radar targets are being increasingly displayed with electronic chart  data as an underlay. This is outlined in Section 22.6, together with other user interface  issues. 
 Data Details3.1. Data for Estimating TEC Precision of PolSAR The spaceborne L band PolSAR data for TEC retrieval were obtained from the Phased Array type L-band Synthetic Aperture Radar (PALSAR) of the Japanese Advanced Land Observation Satellite (ALOS) which orbits Sun-synchronously at about 692 km of altitude (data access https://vertex. daac.asf.alaska.edu/ ). 
 MTI RADAR  2.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 These limitations, plotted in Figure 2.23 and Figure 2.24, apply to all cancelers, whether  single or multiple. (The derivation of these limitations and a means of avoiding them  by the use of time-varying weights are given in “Stagger Design Procedures” in  Section 2.8.) 2.7 OPTIMUM DESIGN OF CLUTTER FILTERS The statistical theory of detection of signals in gaussian noise provides the required  framework for the optimum design of radar clutter filters. Such theoretical results  are important to the designer of a practical MTI or MTD system, in that they estab - lish upper bounds on the achievable performance in a precisely specified clutter  environment. 
 Gilmour, Jr., Microwave Tubes , Norwood, MA: Artech House, 1986, Chap. 14. ch10.indd   29 12/17/07   2:19:39 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 F. Guarguaglini: Clutter Residues of a Coherent MTI Radar Receiver, IEEE  Trans., vol. AES-5, pp. 
 0  0 I  1,000 -- 10'---L-.J....--L-...,_,...LJ_,_,_,__..L.-...,___-"--1-lc....><JW-J..'---~....__._ ......... '-'-' ......... ...._~.._._._....._.___...........,  10 100 1,000 !0,000 100,000  Rodar frequency, MHz  Figure .J.I Doppler frequency (Eq. 
 5, pp. 479–487, May 2001. 122. 
 DEGREE AZIMUTHAL RESOLUTION v 3TANFORD %LECTRON ,AB 4ECH 2EPT  35 
 When the pulse-compression filter is thought of as a  dispersive delay line, its action can be described as speeding up the higher frequencies at the  trailing edge of the pulse relative to the lower frequencies at the leading edge so as to compress  the pulse to a width 1/B, where B = f2 - f, (Fig. 1 1.15d). When the pulse compression filter is  considered as a matched filter, the output (neglecting noise) is the autocorrelation function of  Antenna  t To  IF Pulse  Mixer -+- amplifier - compression +  filter amplifier I :  Figure 11.14 Block diagram of an FM pulse compression radar. 
 4th, 1974.  38. Barbe. 
 Blackman, R. B., and J. W. 
 58. N. Vandenberg, D. 
 In particular, issues were addressed related to multi-angle and wide-angle acquisition modes, which, in the last years, have been becoming more and more common. Several SAR systems were considered, including spaceborne and aerial platforms, light unmanned vehicles, as well as ground-based radars. Speciﬁc aspects of SAR signal propagation (e.g., in ionosphere) and back-scattering (e.g., anisotropic backscattering, ocean eddies) were also investigated though modelling and simulation. 
  4HE ADOPTION OF SOLID 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters.  SOLID-STATE TRANSMITTERS  11.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 In this example, a GaAs PHEMT with 1 mm of total gate periphery (Figure 11.11) is  compared with an identical 1 mm GaN HEMT (Figure 11.12). 
 BASED RADARS EG  RADARS SITED ON LAND OR INSTALLED  ONBOARD SHIPS &OR AIRBORNE RADAR  RAPID PLATFORM MOTION HAS A SIGNIFICANT EFFECT ON DESIGN AND PERFORMANCE AS DISCUSSED IN #HAPTERS     AND  OF THIS (ANDBOOK 4HE FUNDAMENTAL THEORY OF MOVING TARGET INDICATION -4)  RADAR  AS PRESENTED IN THE  PREVIOUS EDITIONS OF THE  2ADAR (ANDBOOK  HAS NOT MATERIALLY CHANGED 4HE PERFORMANCE  OF -4) RADAR  HOWEVER  HAS BEEN GREATLY IMPROVED  DUE PRIMARILY TO FOUR ADVANCES    INCREASED STABILITY OF RADAR SUBSYSTEMS SUCH AS TRANSMITTERS  OSCILLATORS  AND RECEIVERS    INCREASED DYNAMIC RANGE OF RECEIVERS AND ANALOG 
 C.E.Schensted. andI.V Schensted: Bistatic RadarCrossSections ofSurfaces ofRevolution, J.Appl.P/I\'S.,vol.26. pp.297-305, March,1955. 
 Another problem is to know when graceful degradation has  gone too far and maintenance is needed.  The full testing of an array radar system is often more complicated than with conven-  tional radar systems. Also, the incorporation of IFF can be more complicated than with  rotating antennas. 
 Assume aconstant pulse repetition frequency of500 pps. Let usbegin with the antenna stationary, pointing atasingle target. The number ofsweeps available forintegration, n~,will belimited bythescreen per- sistence and will be4secX500 see–l, or2000. 
 7.11~ total pat11 le~igtli (L), + L),), of tra~isit time, of the scattered signal.  2. The angle of arrival of the scattered signal. 
 Moore ,37 © IEEE 1984 ) ch15.indd   13 12/15/07   6:17:00 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter. 
 The later H 2S Mk. IIA was also ﬁtted with a horn feed. The connection from the transmitter to the antenna was a coaxial line. 
 typically).86 Figure 5.25  (lower left and lower right) shows the situation geometry of an aircraft flying toward  two hills and the corresponding altitude cuts displayed to the pilot. This allows either  manual or automatic turning flight to maintain a lower altitude. TF/TA allows an aircraft to penetrate at low altitude using the terrain as masking,  thus preventing early detection. 
 This target-specific loss is the detectability loss in the main  channel caused by spurious blanking from the guard channel. (See Figure 4.1 1.) Probability of False Alarm.  Radar detection performance is determined by  the detection threshold, which in turn is set to provide a specified probability of  false alarm.64–68 As described in Section 4.4, pulse doppler radars often employ  a multilook detection criterion to resolve range ambiguities. 
 C. Goutelard, “The NOSTRADAMUS project: French OTH-B radar design studies,” 47th  AGARD Symposium on ‘Use or Reduction of Propagation and Noise Effects in Distributed  Military Systems’ , AGARD CP-488 (Supp.), Greece, October 1990. 12. 
 10.4  10.5 Pulse Compression Devices  ...................................  10.6  Digital Pulse Compression  .................................  10.7  Surface-Wave Pulse Compression  ..................... 
       
 If the required scaa angle can be  limited to a much smaller angular region the number of radiating elements and the number of  phase shifters can be reduced. This can result in a simpler and cheaper phased-array radar  than the conventional array that must scan a wide angle in two orthogonal coordinates.  Although the conventional phased-array radar has not seen extensive application because of  its high cost and complexity, the limited-scan array has had significant application because it is  more competitive in both performance and cost to mechanical scanning antennas. 
 Similarly, higher-order delay- line filters (with or without feedback) are synthesized on the basis of stopband rejection. The limiting case is the narrowband filter bank where each individual filter consists of a small passband, the balance being stopband. Platform-Motion Effect. 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing.  RADAR DIGITAL SIGNAL PROCESSING  25.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 seen to be a combination of spectral components of the form A e j2p  ft. Sampled signals  have t = nT with T a sampling interval and n an integer time, but sampled or not, the  basic component form is the same. 
 The space environment itself can determine the selected orbit if the natural-radiation lifetime dosage that the SBR electronics receives is too large. Finally, there is the requirement to use the least number of satellites to keep total system cost to a minimum. Considerations Orbit Selection. 
 OBSERVING REAL 
   L    4HE RANGE OF DOPPLER FREQUENCIES RECEIVED FROM THE SCENE IS  $F6 $6 $D   LL    4HUS  TO AVOID VELOCITY AMBIGUITY  THE 02& MUST BE AT LEAST 6$ 7RITING   F6 $T2 2MIN MAX       WE HAVE  6T$ 2MAX      4HUS   THE DISTANCE TRAVELED BY THE PLATFORM DURING THE TIME BETWEEN PULSES  T2  MUST  BE NO MORE THAN  $  AND THE 3!2 MUST TRANSMIT AT LEAST TWO PULSES AS ITS PHYSICAL  ANTENNA PASSES A STATIONARY POINT IN SPACE 7E ALSO FREQUENTLY WANT RANGE 
 In addition, we study the effects of noise on aspect entropy extraction. Aspect entropy is more accurate in a high signal-to-noise ratio (SNR). Only high scatterings are interested in the RCS curve of the anisotropic target. 
 messfacilities. etc.)canbeasignificant fractionofthetotal. Although thebistaticradarcannotreadilyimitatethehemispherical coverage ofmono­ staticradar,itispossible forthemonostat.ic radartogivefencecoverage byusingfixed,rather thanrotating. 
 the receiver noise-figure.  The sensitivity of a radar may be visually displayed by using the measurement of receiver  noise to display the normal range rings on the PPI only within the range at which the radar  can detect targets reliably. This provides the operator with a continuous and immediate  indication of radar sensitivity. 
 Choose 53 dBW for Pav, 20 dB for Gn 30 dB for G,, O dBs for T9 20 dBsm for RCS, and 6 dB forFp. SNR = 53 + 20 + 30 + 25 + O + 20 + 6 - 33 - 261 - ( - 175) = 35 dB.GREAT-CIRCLE TIME DELAY (ms) GROUND RANGE (nmi) . Ground Range (nmi) FIG. 
 Meteor. Soc.)  rate is sliown plotted in Fig. 13.12. 
 As shown in ﬁgure 7.4,r eﬂectivity is a function of radar frequency, grazing angle and sea state. The clutter-limited detection sensitivities for ASV Mk. III and ASV Mk. 
 If KN pulses are in the 3-dB beam width, K pulses are summed (batched) and either a O or a 1 is declared, de- pending on whether or not the batch is less than a threshold T1. The last TV zeros and ones are summed and compared with a second threshold M. An alternative version of this detector is to put the batches through a moving-window detector. 
 DOMAIN REPRE 
 OFF  TIMES  CAN CONFUSE AN !2- SEEKER AND GUIDANCE OR A $& RECEIVER $ECOY TRANSMITTERS  RADIATING FROM ANTENNAS NOT LOCATED AT THE RADAR  MAY ALSO BE EMPLOYED TO CONFUSE $& RECEIVERS AND !2-S THESE DECOYS CAN ALSO OPERATE IN CONJUNCTION WITH THE RADARS IN A BLINKING MODE 0ROPER SITE SELECTION FOR GROUND 
 Examples  include a Recursive Least Squared algorithm, Q-R decomposition with Gram-Schmidt  orthogonalization, or a Householder Transformation. The adaptive weights are then  applied to the received signals and beamformed to generate three sum channel detec - tion beams: undelayed, one-PRI delayed, and two-PRI delayed beams. These beams  are, in turn, added together to form the final STAP weighted detection beam. 
 D. Anderson, “Radar detection of low-altitude targets in a maritime environment,” IEEE  Transactions on Antennas and Propagation , vol. 43. 
 Figure 19.10  shows another example of precipitation intensity and air motion fields superposed on  a photograph of a convective thunderstorm cell. The data are taken from three doppler  radars spaced about 40 km apart. A developing network of short range doppler radars not range limited by the Earth’s  curvature will provide more detailed observations close to the surface than the rela - tively widely spaced WSR-88D network. 
 COUNTERMEASURES AGAINST INVERSE GAIN JAM 
 TIONS IS A CONSTANT  2K   4 )N THIS CASE  THE +ALMAN FILTER DESCRIBED IN %QS  TO   HAS GAINS THAT ARE A FUNCTION OF THE DIMENSIONLESS TRACK 
 Due to this simplification, CIC decimators are generally implemented in this form. FIGURE 25.36  (a) CIC decimation filter and ( b) CIC interpolation filterR+ ++ − Dt DtR+ ++ − INTEGRA TORCOMB INTEGRA TOR COMB (a) (b)t t ch25.indd   29 12/20/07   1:40:35 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 MENTATIONS USED ANALOG PRODUCT DETECTORS TO EXTRACT ) AND 1 BASEBAND SIGNALS  WITH SEPARATE !$#S IN THE ) AND 1 BASEBAND CHANNELS #ORRELATION -IXER /UTPUT 3IGNAL !NALYSIS  4HE RECEIVED SIGNAL AT THE #- INPUT  PORT FROM A POINT TARGET IS   XT !TFFTD INRECT4  COS;    
 6ORONOVICH4!",%    3CATTERING #OEFFICIENT 6ARIATION.   '2/5.$ %#(/  £È°££ 3MALL 
 TION LOBE COMPENSATION  ANGLE RATIO TESTS SEE &IGURE  AND THE hFRINGE REGIONv FOR AN EXAMPLE ANGLE 
 RANGE SURVEILLANCE RADARS THAT EMPLOY ,&- WAVEFORMS 4HE ANTENNA IS MECHANICALLY ROTATED IN AZIMUTH  AND ELECTRONIC PENCIL 
 TIME IONOSPHERIC MODEL 24)-  THAT IS INTIMATELY LINKED WITH THE RADAR SUBSYSTEMS  SERVING TO GUIDE FREQUENCY SELECTION  RADIATED POWER  TASK SCHEDULING  COORDINATE REGISTRATION CONVERTING FROM THE RADAR COORDINATES OF TIME DELAY AND ANGLE 
 Schwan, H. P., and K. Li: Hazards Due to Total Body Irradiation by Radar, Proc. 
 and R. W. Boglc: Directional Sea Spectrum Ueterrnina-  tion Using f1F I)opplcr Radar Techniques. 
 CENT MOLECULES THEN SENSE EACH OTHER AND FORM A FILM THAT IS RESISTANT TO HORIZONTAL COMPRESSION 4HE SURFACE ELASTICITY IS CHANGED  A TYPE OF LONGITUDINAL VISCOSITY IS INTRODUCED  AND THE SURFACE BECOMES STABILIZED AGAINST THE GROWTH OF SHORT WAVES UP TO SEVERAL INCHES IN LENGTH   4O THE EXTENT THAT RADAR SEA CLUTTER IS PRODUCED BY SMALL 
 CALLY FOR THE (& ENVIRONMENT TO ADDRESS THE REJECTION OF NONSTATIONARY INTERFERENCE WHILE PROTECTING THE CLUTTER DOPPLER SPECTRUM PROPERTIES ! METHOD FOR TIME 
 Bending, or refraction, of radar waves in the atmosphere is  caused by the variation with altitude of the velocity of propagation, or the i11di!x of n!{N1etio11.  defined as the velocity of propagation in free space to that in the medium in question.  At microwave frequencies, the index of refraction II for air which contains water vapor  is 11. 
 The Range PSLR is −8.31 and the azimuth PSLR is −6.37. 20. Sensors 2019 ,19, 1701    (a) Imaging result of targets (b) Interpolation of a single point target     (c) Profiles of range-spread function (d) Profiles of azimuth-spread function  Figure 14. 
 (7.11) and (7.14) applies only  when the signal is a CW sine wave. If the signal were a pulse or some other radar waveform  with a spectrum of noninfinitesimal width, the simple Fourier integral which applies to a CW  sine wave would not give the correct radiation pattern nor would it predict the transient  behavior. In most cases of practical interest the spectral width of the signal is relatively small,  with the consequence that the pattern is not affected appreciably and the Fourier-integral  relationships arc satisfactory approximations. 
 n 102103104105106 10.log 10(signal to noise ratio (SNR)) −119−96−73−50−27 The negative value of SNR ( −27 dB) can be further reduced by multiple coherent summations of the current complex image with the previous one after each accomplishment of the image reconstruction procedure. 6.2. Range Compression of the ISAR Signal Considering that the ISAR signal reemitted by the asteroid is registered in a time-frequency grid, the range compression can be performed by the algebraic summation of signals from all frequency channels. 
 TINELY AS CALIBRATION TARGETS FOR 2#3 MEASUREMENTS BECAUSE AN EXACT SOLUTION IS AVAILABLE METAL SPHERES ARE NOT VERY HARD TO BUILD AND EFFICIENT COMPUTER CODES ARE AVAILABLE FOR OBTAINING THE EXACT SOLUTION .O OTHER SCATTERING BODY AFFORDS ALL THESE CONVENIENCES )NTEGRAL %QUATIONS  -AXWELLS EQUATIONS MAY ALSO BE MANIPULATED TO GENERATE A  PAIR OF INTEGRAL EQUATIONS KNOWN AS THE 3TRATTON 
 K.: Tutorial Review of Synthetic- Aperture Radar (SAR) with Applications to Imaging of  the Ocean Surface. 1'1.o~. IEEE. 
 Tentatively uncorrelated  DF signal probably does not go with any radar track  when TM > Pmax > TL. 5. Firmly uncorrelated DF signal does not go with any radar track when TL ≥ Pmax. 
 SEA  CONDITIONS IS UNCERTAIN AND THOSE FROM OTHER FIXED 
 IF.EE Tra11s .. vol. AC-8. 
 Excessive energy causes the diode to open-circuit or the  semiconductor to puncture, resulting in failure of the device. As defined above, however,  burnout of a diode can occur before the onset of physical destruction. An increase in the  receiver noise due to the effects of excessive RF energy can be just as harmful as complete  destruction; perhaps more so, for gradual deterioration of performance might not be noticed  as readily as would catastrophic failure. 
 Hence, theyusuallymustbeoperated inatemperature-controlled environment. Although theReggia­ Spencer phaseshifterhasbeensuccessfully applied inoperational radarandwasoneofthe firstpractical phaseshifterssuitable forrauar,initspresentformithasbeenlargelysuperseded byotherdevices, Latchin~ ferritephaseshifters,'''·.o Theuseofaferriteintheformofatoroidcentered withina waveguide asinFig.X.l0.resultsinaphaseshifterwithafastswitching timeandwithless drivepowerthanrequired ofaReggia-Spencer device.Furthermore, itisnotastemperature sensitive, andthereislessofaproblem causedbyhysteresis intheferrite.Thetoroidferrite phaseshifter.although notperfectbyanymeans,hasbeeninthepastapopular choicefor phasedarrayapplication. Consider thehysteresis loop,orB-Hcurve,ofFig.8.11.Thisisaplotofthemagnetization (gauss)asafunction oftheapplied magnetic field(oersted) foratoroid-shaped sectionof ferrimagnetic material. 
 Functionally, these are all  equivalent, but the partitioning of circuit functions is dependent on the capability  of the MMICs used, and different implementations may be required to address a  key reliability requirement or a key performance parameter. For example, the use  of a single high performance power amplifier may obviate the need for combin - ing two lesser power amplifiers together to achieve the same performance. These  represent cost, capability, and availability trades that might be exercised by the  T/R module architect. 
 FED THROUGH A PHASE SHIFTER SO THAT THE ELEVATION BEAM PAT 
 The command may include a phase correction for the correction of errors due to component tolerances. An adder at each element provides rapid steering through the use of row-and-column steering commands. If high-speed phase shifting is not required, the computer may compute sequentially and store the phases for each of the elements. 
 The pattern here has adapted to minimize the total energy  collected in the doppler bands [–5,–1] Hz and [1,5] Hz, whilst maintaining the array  FIGURE 20.23  Comparison of doppler spectra estimated by (i) conventional beam - forming (CBF) and (ii) spatially adaptive processing designed to minimize energy out - side the low-doppler clutter. The noise (and any fast clutter) has been reduced by ~ 20 dB,  which improves detectability of fast targets; note that the sea clutter spectrum changes  as a consequence of the new array pattern, i.e., the clutter spectrum does not necessarily  represent the clutter spectrum from the cell of interest. ch20.indd   52 12/20/07   1:16:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 /Ê/ 
 ASPECT RATIO ANTENNA IS A NOTABLE DEPAR 
 81-82.  139. Lewis, B. 
 Pulse-to-pulse radar cross section is available, but for convenience in presenting the  data the values plotted usually are an average of a large number of values taken within a 10 by  10" aspect angle interval. Examples of such data are given in Figs. 2.18 to 2.20. 
 ASPECT 3EARCH &ORWARD 
 ˆedr2 is non-dimensional. 5.2. Real Data To validate the EMAM method in practical applications, this section gives the results of real airborne SAR data based on the different methods. 
 Davis: Radar Sea Return-JOSS 11, Nacul Resrurch  Laboratory Report 7534, Washington, D.C., Feb. 21, 1973.  6. 
 LOOKING AIRBORNE RADAR v )%%% 4RANS  VOL !%3 
 The active element in each final transmitter stage can be either a traditional vacuum tube9 or a solid-state device.10 If the radar is to perform wide-area surveillance, frequent frequency changes are required in order to cover the various range extents. In addition, relative phase or time-delay changes are required in each amplifier chain to accomplish azimuthal steering. Reference 11 contains a discussion on modern high-efficiency amplifier designs for broadcasting; while some of the techniques are useful in radar transmitters, the final amplifiers tend to be narrowband. 
 14.15. The absorption due to oxygen at 60 GHz (5-crn  wavelength) in the clear atmosphere is quite large (about 16 dB/km). Operation at that  frequency is almost useless for radar applications within the earth's atmosphere. 
 Each of these  harmonics off~ is modulated by a doppler-frequency component with amplitude proportional  to J"(LJ). The product of the doppler-frequency factor times the nth harmonic factor is equiva­ lent to a suppressed-carrier double-sideband modulation (Fig. 3.15). 
 TRACK PATTERN 4HUS  IF THE ANTENNA PATTERN IN THE ALONG 
  
 D.: Circular Polarization Cµts Rain Clutter, Electronics, vol. 27, pp. 158-160, March,  1954. 
 TRAFFIC CONTROL RADARS  ALL IMPORTANT MILITARY GROUND 
 Adequate heat sinking of the chip is mandatory. (4) For efficient multiple-stage designs, it is necessary that the final stage of the amplifier reach saturation before the preceding stages. This must be addressed in the circuit design. 
 In amplitude comparison monopulse, the antenna-beamformer generates a pair of sum and difference beams which, without loss of generality, may be assumed to be in phase, in the sense that their ratio is real. In phase comparison monopulse, two or more an- tennas or sets of radiating-receiving elements, physically separated in the eleva- tion dimension, are used to generate two beams which have ideally identical pat- terns except for a phase difference which depends on the angle of incidence of the received target echo. Each of these techniques may be converted to the other, either in concept through mathematical sums and differences or physically through the use of passive RF hybrid combining devices. 
 TO 
 (icril, I I.: he I(oorl;~cc Acrial, I<R/ J. (Royal Radar Establislinicrit. Malver~i. 
 Maximal-Length Sequences.  Maximal-length sequences have a structure simi - lar to random sequences and, therefore, possess desirable autocorrelation functions.  They are often called pseudorandom noise  (PRN)  sequences. 
 POLARIZATION CAPABILITY  AND SOME ARE CAPABLE OF POLARIMETRY BECAUSE THE PHASE OF TWO RECEIVED SIGNALS WITH ORTHOGONAL POLARIZATION CAN BE MEASURED  4HE BASIC ELEMENTS OF AN &- 
 (ILL    ! ) :VEREV  (ANDBOOK OF &ILTER 3YNTHESIS  .EW 9ORK *OHN 7ILEY AND 3ONS  )NC    ! 6 /PPENHEIM AND 2 7 3CHAFER   $ISCRETE 
 13.3 is  21· ( ,,2 ) 11(1·) = exp -· (Tl (Tl {I>(} ( IJ.JO)  where <r2 is the mean square value of 11. The Rayleigh pdf has the property that the rms  amplitude of the lluctuations about the mean (denoted by c'>11;0) is proportional to the mean f•;0•  or ,51·111 = kt\11• I\ logarithmic receiver has the characteristic  """' = ll log hv;n (13.31)  The slope of the logarithmic receiver characteristic at i\0 is  !}1•ou1 a  !}vin i\n (13.32)  If the input clutter fluctuations c'h:;0 arc small compared to the total range of the logarithmic  characteristic. the output lluctuations ,51•0111 arc approximately  (I  1)!'ou1 = slope X <)!';0 = _ <)V;0 = ak  V;n  Thus the output fluctuations arc constant, independent of the input mean. 
 Beacons used with microwave radar hav- ingPPI presentation give most satisfactory navigational fixes by graphically locating the aircraft with respect toseveral known points onthe ground. Figure 8.4shows one ofthe AN/CPN-6 beacons, a3-cm beacon ofhigh power designed for use inair navigation. FIG. 
 Except, perhaps, when microwave frequencies areused inthe radio link, theultimate limit ofsensitivity isusually setbythedegree ofoutside interference rather than bythe inherent signal-to-noise ratio ofthe receiver. Many factors must beconsidered intrying tominimize the effects ofthis interference. 1.The strength ofthe desired signals atthe receiver input terminals should bemade ashigh asfeasible compared with that ofthe interference. 
 319-328, March 1978. 6. Ringel, M. 
 Since the whole ofthe 10-db differential between the two sets had been used upinthe smaller antenna and the lower pulse power ofthe AN/APS-10, itwas necessary tomake sure that the receiver sensitivity ofthelatter setdid not fall below that ofthe AN/APQ-13. Further, special pains had tobetaken toprovide good range performance against microwave beacons. IntheAN/APQ-13, theTR-switch tuning was not changed from search tobeacon operation, and anarrow-band ATR was used. 
 161. Ricardi, L. J.: Array Beam-Forming Networks, MIT Lincoln Lahoratory Teclinical Note 1965-12. 
 However, much of the same benefit of wide unambiguous doppler coverage can be obtained by a compro- mise waveform called burst, in which a finite group of high-PRF pulses is trans- mitted; the duration of the burst is made short enough to avoid making long-range target echoes compete with short-range clutter echoes. A further disadvantage of CW radar is that it requires two antennas, which ef- fectively "wastes" 3 dB of range-equa- tion performance that could be gained if that total aperture area were combined into a single antenna and used for both transmit and receive. Pulsed radar does exactly that; it shares a single antenna for both the transmitter and the receiver by using a duplexer,2 as shown in Fig. 
 30. Wimberley, F. T., and J. 
 GET   OR BY REFLECTING THE RADAR BEAM OFF A COLLIMATING REFLECTOR 4HIS LATTER CONCEPT  IS KNOWN AS THE  COMPACT RANGE BECAUSE A BEAM OF PARALLEL RAYS CAN BE GENERATED IN A  MUCH SHORTER DISTANCE THAN WOULD BE POSSIBLE WITHOUT THE COLLIMATING DEVICE 4HE REFLECTOR OFFERS A DIFFERENT WAY TO COLLIMATE A BEAM )N CONTRAST TO THE LENS   WHICH IS PLACED BETWEEN THE RADAR AND THE TEST OBJECT  THE RADAR AND THE TEST OBJECT REMAIN ON THE SAME SIDE OF THE REFLECTOR  AS SHOWN IN &IGURE  4HE REFLECTOR IS TYPICALLY AN OFFSET PARABOLOID  MEANING THE PARABOLOIDAL SURFACE DOES NOT INCLUDE THE VERTEX OF THE GENERATING PARABOLA 4HIS PERMITS THE FEED THAT EXCITES THE REFLECTOR TO BE PLACED OUT OF THE BEAM REFLECTED TOWARD THE TARGET )F THE TEST OBJECT IS HELD WITHIN ONE OR TWO FOCAL LENGTHS OF THE REFLECTOR AND IF THE REFLECTOR IS EXCITED BY A SUITABLY DESIGNED FEED  THE REFLECTED WAVE IS SENSIBLY PLANAR  (OWEVER  UNLESS THE EDGES OF THE REFLECTOR ARE CAREFULLY DESIGNED  THE INCIDENT FIELD  IN THE TARGET ZONE WILL BE CONTAMINATED BY UNDESIRED FIELDS DIFFRACTED FROM THE EDGES OF THE REFLECTOR 4HE DIFFRACTION CAUSES RIPPLES IN BOTH THE AMPLITUDE AND THE PHASE OF THE FIELD DISTRIBUTION IN THE TARGET ZONE )N SOME CASES  THE EFFECT IS SMALL ENOUGH TO BE IGNORED  BUT IN HIGH 
 119--125 doppler filterbank.127 doubledelay-line canceler, 109 DPCA. 143-144 externally coherent, 138 filterbank.121-125, 127 1Fcancellation, 126 improvement factor: antenna scanning. 134-136 antenna sidelobes, 145 clutterOuctuations, 131-134 definition. 
 GAUSSIAN SEA CLUTTER v  )%%% *OURNAL OF  /CEANIC %NGINEERING  VOL   NO   PP n  !PRIL   % #ONTE  ! $E  -AIO  ! &ARINA  AND ' &OGLIA  h#&!2 BEHAVIOR OF ADAPTIVE DETECTORS AN  EXPERIMENTAL ANALYSIS v )%%% 4RANS  VOL !%3n  NO   PP n  *ANUARY   - # 7ICKS  7 * "ALDYGO  AND 2 $ "ROWN  h%XPERT 3YSTEM !PPLICATION TO #ONSTANT &ALSE  !LARM 2ATE #&!2  0ROCESSOR v 53 0ATENT       -ARCH   .   %,%#42/.)# #/5.4%2 
 RADAR ANTENNAS 275  51. Kock. W. 
 The other limiter is between the pulse-compression filter and the MTI and has a  dynamic range equal to the expected MTI improvement factor.  The technology of pulse compression has been applied to radar with conventional, unmod-  ulated pulses to achieve CFAR (constant false alarm rate) performance better than that of the  log-FTC. In one example,40 a dispersive delay line with a linear time-delay vs. 
 /Ê /",Ê   1 /" - 5SING "ARTONS APPROACH  THE MAXIMUM IMPROVEMENT FACTOR  ) AGAINST ZERO 
 WAVE RESONANT MICROWAVE STRUCTURES 4HESE DEVICES EMPLOY A FAST 
 Installation ofSurface-based Scanners.-The installation of scanners onshipboard presents asiting problem slightly simpler than in theairborne case. Itisnecessary toavoid locations where thestructure ofthe ship will blank the radiation orproduce spurious reflections. Sometimes itbecomes necessary toinstall two scanners, each ofwhich covers theregion inwhich theother isblind. 
 TIME ANTENNA PATTERN CONTROL IS ACCOMPLISHED BY ADJUSTING THE WEIGHTS AT EACH RECEIVER TO MAXIMIZE SIGNAL 
 The adja - cent molecules then sense each other and form a film that is resistant to horizontal  compression. The surface elasticity is changed, a type of longitudinal viscosity is  introduced, and the surface becomes stabilized against the growth of short waves up  to several inches in length.81,82 To the extent that radar sea clutter is produced by small-scale surface roughness (at  grazing angles less than about 80°), the presence of oil on the surface should lead to  a measurable decrease in clutter cross section. But, as noted above, the reduction of  small wave motions requires the existence of a continuous  monolayer; slick formation  is a go–no-go process, and so slicks will tend to have relatively sharp boundaries. 
 Often in  SAR, the transmitted pulse is much larger than the range swath, Rswath. Clearly, in  each of the cases, the nearest integral clock interval and nearest convenient pulse  compression ratio is selected because the values in Eq. 5.4 will be clock integers only  by coincidence. 
 86. Mortley, W. S., and S. 
 C., and J. F. Kauffmnn: A High Temperature Luneburg Lens, Proc. 
 The low-level neural layers learned by deep learning models are useful for extracting features such as corners, edges. So, we make the assumption that the lower level neural layers share common features. The methods take the weights of the models in the low-level features as the inputs instead of random weights. 
 OF 
 ING IS PERFORMED CAN BE FLEXIBLE TO MEET CHANGING OBSERVATIONAL REQUIREMENTSSHORT RANGE INTERVALS FOR HIGHLY STRUCTURED HEAVY RAINFALL STORMS TYPICALLY CONVECTIVE  AND LONGER RANGE INTERVALS FOR MORE UNIFORM BUT WEAKER RAINFALL TYPICALLY STRATIFORM  )N OTHER SITUATIONS WHERE SIGNALS ARE VERY WEAK SUCH AS FOR WIND PROFILER APPLICATIONS AND CLEAR AIR BOUNDARY LAYER OBSERVATIONS   PULSE COMPRESSION MAY BE USED TO INCREASE SYSTEM SENSITIVITY  BY INCREASING THE AVERAGE POWER OF THE SYSTEM USING LONG PULSES  WHILE PROCESSING FOR ANY DESIRED RANGE RESOLUTION 2ANGE RESOLUTION AND 3.2 ARE INDE 
 14.13) the small phasor will, except at the turnarounds, swing either clockwise or counterclockwise at a uniform rate. If the swing is short (i.e., the range to the ground is short), then, depending on the phase, either of two situations results: Fig. 14.14« or b. 
 STAGE  PIPELINED #/2$)# PROCESSOR SHOWN IN THE FIGURE WOULD HAVE A LATENCY EQUIVALENT TO EIGHT CLOCK PERIODS AND A THROUGHPUT EQUIVALENT TO THE CLOCK RATE IE  ONCE THE PIPELINE IS FILLED AND THE FIRST RESULT IS AVAILABLE ON THE OUTPUT  SUCCESSIVE CLOCKS WILL PRODUCE NEW OUT 
 433-441, April, 1972.  78. Richter, J. 
 \,,~~FREQUENCY-SCAN ARRAYS63-65 Achangeinfrequency ofanelectromagnetic signalpropagating alongatransmission line produces achangeinphase,aswasindicated byEq.(8.15).Thisprovides arelatively simple meansforobtaining electronic phaseshift.Although parallelfeedingofafrequency-scan array ispossible, itisusuallysimplertoemployseriesfeeding,asinFig.8.14.Sincetheattenuation inthetransmission lineconnecting adjacent elements issmallcompared withthatofconven­ tionalphaseshifters,theseries-fed arrangement canbeusedinfrequency-scan arrayswithout excessive loss. Input Snokefeed/elements Figure8.14Series-fed, frequency-scan lineararray.. The phase difference between two adjacent elements in the series fed arra) of Fig. 
 Since the elements on the side of the cylindrical array  opposite from the direction of propagation do not contribute energy in the desired direction,  they are not excited. Unlike the planar array, the circular symmetry ensures that mutual  coupling between elements is always the same as the beam scans in azimuth.  The truncated cone has similar properties to the cylindrical array, and might be utilized  instead of the cylinder when the beam is to be scanned in elevation as well as azimuth. 
 of a small aircraft)   1 m2   MDS echo PMDS 5 · 10 -15 W -113 dBm   Sum of losses (see: Table 2) LS 128.8  21.1 dB  . Radartutorial (www.radartutorial.eu)   17    Figure 2 2: Block diagram of a frequency -diversity radar  Frequency -diversity Radar   In order to overcome some of the target size fluctuations many radars use two or more different  illumination frequencies. Frequency diversity typically uses two transmitters operating in tandem to  illuminate the t arget with two separate frequencies like shown in the following picture. 
 Inaradarwithoverlapping rangegates,thegatesmayhewiderthanoptimum for practical reasons. Theadditional noiseintroduced bythenonoptimum gatewidthwillresultin somedegradation. Thestraddlillg lossaccounts forthelossinsignal-to-noise ratiofortargets notatthecenteroftherangegateoratthecenterofthefilterinamultiple~filter-bank processor. 
 SARY TO TRADE ENERGY FOR TIME IN ORDER TO ACHIEVE THE DESIRED SEARCH FRAME TIME &)'52%    ! SPOILED TRANSMIT BEAM AND A  CLUSTER OF FOUR SIMULTANEOUS RECEIVE BEAMS . 
 Noone deviceseemstobesufficiently universal tomeettherequirements ofallapplications. Inthistextadeviceforonlaining achangeofphaseiscalledaphasesh(fier, buttheyhave aIsobeenknownasl"lllscrs. f)i~ilall~' switchro phaseshifters. 
 Detection of radar echo signals is usually (with some exceptions) accomplished by first integrating (e.g., adding) a sequence of received pulses and basing the detection decision on the resultant integrated signal voltage. Integrators that perform this operation will of course necessarily add noise as well as signals, but it is demonstrable that the ratio of the added signal voltages to the added noise voltages will be greater than the preintegration signal-to-noise ratio. Stated otherwise, the detectable signal-to-noise ratio evaluated ahead of an integrator will be smaller than when detection is performed by using single pulses. 
 SANDWICH  # 
   39.4(%4)# !0%2452% 2!$!2   £Ç°Îx   2 / (ARGER   3YNTHETIC !PERTURE 2ADAR 3YSTEMS 4HEORY AND $ESIGN   .EW 9ORK !CADEMIC  0RESS     2 "IRK  7 #AMUS  % 6ALENTI  AND 7 -C#ANDLESS  h3YNTHETIC APERTURE RADAR IMAGING SYSTEMS v  )%%% !%3 -AGAZINE  PP   .OVEMBER   # *ACKSON AND * !PEL DECEASED THE BOOK IS DEDICATED TO HIM    3YNTHETIC !PERTURE 2ADAR -ARINE  5SERS -ANUAL  7ASHINGTON  $# $EPARTMENT  OF #OMMERCE  .ATIONAL /CEANIC AND  !TMOSPHERIC  !DMINISTRATION ./!!      $ !USHERMAN  ! +OZMA  * 7ALKER  ( *ONES  AND % 0OGGIO  h$EVELOPMENTS IN RADAR IMAGING v  )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS  VOL !%3 
 34.Ronconi, R.:L-bandSolid-state PowerAmplifier, RevistaTeOlica Selenia, vol.2,no.3,pp.21-32, 1975. 35.Davis,M.E.,J.K.Smith,andC.E.Grove: L-band T/RModule forAirborne Phased Array, flticrowal'l:' i.,vol.20,pp.54-61,February, 1977. 36.Kawamoto. 
 andadecreasc inmoisture content. Thusthiswarmer, drierairliesabovethe coolet.Illoistail10plOduce aIcmperature inversion; i.e.,lUIincrease.ill tcmperature with height.Thisresultsinastrongductalongtheinterface ofthetemperature inversion. Insome cases.astratuscloudlayerwillformatthebaseofthetemperature inversion.27Thustheduct altitude canbcidentified bythcheightofthecloudtopsthatarcsuppresscd bythetcmpcra­ turcinversion, Whcnthetemperature inversion occursbelowthealtitude atwhichcloudsare formed. 
 Tile ovcrall cikct on tile  tracker is somewl~at analogous to "glint" (Sec. 5.5).  12.3 THE ROUND EARTH J  In general, the curvature of the earth cannot be neglected when predicting radar coverage. 
 71.Hsiao,J.K.:MTIOptimization inaMultiple-Clutter Environment, NRLReport7860,Nal'ul Research Laboratory, Washington, D.C.,Mar.20,1975. 72.Hsiao,1.K.:ADigitalMean-Clutter-Doppler Compensation System,NRLMemorandum Report 2772,NavalResearch Laboratory, Washington. D.C.,April,1974. 
 By  traveling the quarter wavespace twice, this component is shifted by 180° in phase.  When added to the reflection from the grid, it results in a 90° change in polariza - tion. The total reflected energy from the mirror rotated by 90° will efficiently pass  through the wire-grid paraboloid. 
 VARYING INTERFERENCE ENVIRONMENT 4HE GOAL IS TO PRESERVE THE DESIRED SIGNAL WHILE SIMULTANEOUSLY REDUCING UNWANTED INTERFERENCE 4HIS REAL 
 COM-21,  pp. 591-605, May, 1973.  57. 
  ARRAY APPEARS REASONABLE &OR AN ARRAY OF OPEN 
 A sensitive receiver with a low noise figure may be desirable in many civilian applications  of radar, but in military applications it is not always an asset since it makes the receiver more  vulnerable to jamming. Most low-noise receivers also have less dynamic range than one with a.  mixer front-end. 
 CORRELATION FUNCTION IS THE MUTUAL COHERENCE FUNCTION   G           ;\ \= ;\ \=TT2T T %S %S      IN  PARALLEL TO THAT ENCOUNTERED IN PHYSICAL OPTICS 'AMMA IS A QUANTITATIVE MAPPING  OF THE COHERENCE BETWEEN THE TWO OBSERVATIONS )N GENERAL  SCENE COHERENCE DECREASES WITH SHORTER WAVELENGTH AND LONGER TIME BETWEEN OBSERVATIONS -UTUAL COHERENCE IS AN ESSENTIAL INGREDIENT FOR RADAR INTERFEROMETRY #OHERENCE  IMPLIES TWO CONSTRAINTS SPATIAL AND TEMPORAL 4HE SPATIAL CONSTRAINT APPLIES TO THE SPAC 
 TION PROBLEM CAN BE FORMULATED AND SOLVED n )N THIS WAY  THE TARGETS CONTRIBUTE TO  REGISTERING THEIR OWN COORDINATES Óä°£ÓÊ , ,Ê, 
 Phased arrays are very expensive. As technology advances, costs are expected to be  reduced. At the same time, the quest for better performance with lower sidelobes and  wider bandwidth keeps the costs high. 
 17.2) isused forthemodulator trigger. Some method must beprovided for separating pulses from video 1This ia,ofcourse, anexample oftime sharing inwhich twoofthesignals coincide. 2Inallthediagrams ofthischapter theindividual blocks arefunctional andare intended toinclude proper input and output circuits including amplifiers, cathode followers, blocking o.willators, etc.. 
 See planetary radars. synthetic aperture radars (SAR), 18. 5 to 18.29 ambiguities, 18.17 to 18.18 ambiguity limits, 18.22 to 18.24 antennas, 18.19 applications, 18.29 data products, 18. 
 12.4 REFRACTION  Radio and radar waves travel in straight lines in free space. However, electromagnetic waves  propagating within the earth's atmosphere do not travel in straight lines but are generally bent  or refracted. One effect of refraction is to extend the distance to the horizon, thus increasing . 
 With a ground-based radar the attenuation is greatest when the antenna points to  the Iiorirorl, atid it is least wlicn it points to the zenith. Figure 12.10 gives examples of  the two-way atterluation for elevation angles of 0 and 5".  12.8 ENVIRONkIENrrAL NOISE  At n~icrowave frequencies the normal noise level is relatively low and thesensitivity of conven-  ,j tional radar receivers is usually determined by internal noise. 
 FACTURED WITH A RESISTIVITY OF  OHMS PER SQUARE THE IMPEDANCE OF FREE SPACE  ALL THE POWER IN THE INCIDENT WAVE IS TRANSFERRED TO THE SHEET AND NONE  IS REFLECTED (OWEVER   THE SINGLE 
 GEN IONS   ORGANIC CARBON CONTENT  #. CARBON 
 The disk canturn atthescanner speed and have asmany slots asthere are markers, oritcan begeared upand have fewer slots. 3.Amethodof using acarrier modulated byasynchro isillustrated inFig. 13.34. 
 Itiscapableofhigh average andpeakpower,highgain,goodefficiency, stableoperation, lowinterpulse noise,and itcanoperate withthemodulated waveforms required ofsophisticated pulse-compression systems. Description, 1\sketchoftheprincipal partsoftheklystron isshowninFig.6.9.Atthe left-hand portionofthefigureisthecathode, whichemitsastreamofelectrons thatisfocused intoanarrowcylindricaIheamhytheelectroll gUll.Theelectron gunconsists ofthecathode, modulating anodeorcontrol grid,andtheanode.Theelectron emission density fromthe calhadeisgcnerally lessthanrequired fortheelectron beam,soalarge-area cathode surfaceis lIsedandIheemitted eleclrons arecausedtoconverge toanarrow beamofhighelectron (knsily. Tilemodulating anode,orotherheamcontrolekctrode, isoftenincluded aspart01" theelectron-gun structure toprovide ameansforpulsingtheelectron beamonandoff.The RFcavities, whichcorrespond totheLCresonant circuitsoflower-frcquency amplifiers, arcat anodepotential. 
 CRATE GRILLWORK REDUCED AIRFLOW  THE INTAKE HAD TO BE ENLARGED TO  RESTORE NORMAL FLOW !ND THE DESIGNERS LATER DISCOVERED THAT THE GRILLWORK TENDED TO ICE UP  WHICH THEY OVERCAME WITH AN ELECTRICAL HEATING SYSTEM 4HE MOST REMARKABLE FEATURES OF THE & 
  REPLACEMENT THAT WAS MOTIVATED BY THE ATTRACTIVE RELIABILITY  MAINTAINABILITY  AND AVAILABILITY CHARACTERISTICS OF A MODULAR SOLID 
 For typical numbers  of pulses in the MTI (three to five), the binomial coefficients are remarkably robust  and provide a performance which is within a few decibels of the optimum. Again, it  should be noted that any attempt to implement an MTI canceler, which performs close  to the optimum, would require the use of adaptive techniques that estimate the clutter  characteristics in real time. If the estimate is in error, the actual performance may fall  below that of the binomial-weight MTI canceler. 
 As a result, it is difﬁcult to separate signals of multiple beams in the frequency domain. Therefore, this paper separates the multi-beam signal in the time domain using three groups of feeders. In order to achieve accurate matching of multi-view SAR images, an improved RMA in a uniﬁed 23. 
 145. W. J. 
 Certain deception jam- mers depend on anticipation of the beam scan or on knowledge or measurement of the antenna scan rate. Random electronic scanning effectively prevents these deception jammers from synchronizing to the antenna scan rate, thus defeating this type of jammer. A high-gain antenna can be employed to spotlight a target and burn through the jammers. 
 (c) Image-reject mixer.RF SIGNAL LOCAL OSCILLATOR LOCAL EL OSCILLATOR RF SIGNALIF SIGNAL IF SIGNAL(Q) (b) RF SIGNALLOCAL OSCILLATORHIGH SIDEBAND LOW SIDEBAND . its odd harmonics are suppressed at the signal input port. Noise sidebands of the LO converted to IF are not rejected by this configuration, however. 
 6~.Crispin. J.W..Jr..andK.M.Siegel:"Methods ofRadarCross-Section Analysis." Academic Press. NewYork. 
 DICTED BY THE EQUATION    SRQ %" '  SEPEAK     WHERE R%   RMS ELEVATION ANGLE MULTIPATH ERROR  SAME UNITS AS P"  P"   ONE 
 . 154 HOW RADAR WORKS  Each ground station has the information that the aircraft  is at a known distance away, so the position lines are  circles with the ground stations at their centres. By  comparing notes the fixed stations can determine the  position of the aircraft, and can then send the ‘mouse’  signal to the navigator, pilot, or bomb-aimer. 
 You, S.; Zhang, Z.; Hongguang, J.I. A thermodynamic constitutive model for creep behavior of rocks and its application. J. 
 (1)gives (2) InEq. (2)R:isthe maximum free-space range forinterrogation ofthe beacon; when itisatgreater ranges itwill not betriggered. The corresponding expression forthereply link is [ 1[$ h’:=&$+(G,,)m.x(G.s)me.x Sr(3) InEq. 
 For this reason, receiver calibration must be performed over a range of input levels, and the nonlinearities must be compensated for in the data processing. CW scatterometers depend on antenna beams to discriminate different anglesTRANSMITTER POWER METER RECEIVEROUTPUT METEROUTPUT METERTRANSMITTER RECEIVER CALIBRATIONSOURCE . of incidence and different targets. 
 The instantaneous fre - quency is plotted as a function of time at three points in the stretch pulse compression  system block diagram: (1) correlation mixer input, (2) correlation mixer LO (reference  waveform generator output), and (3) correlation mixer output (output of bandpass  filter). Three LFM target signals are shown at the correlation mixer input: target 1 is at  zero time offset relative to the reference waveform; target 2 is earlier in time than the  reference waveform; and target 3 is later in time. In each case, the LFM slope for the  target signals is B/T. 
 Dedicated processors, such as FPGAs or ASICs, are typi - cally used in the high-speed front end of radar signal processors, performing demand - ing functions such as digital downconversion and pulse compression, followed by  programmable processors in the rear, performing the lower-speed tasks such as detec - tion processing. The location of the line that separates the two domains is application- dependent, but over time, it is constantly moving toward the front end of the system. 25.6 SUMMARY The purpose of this chapter was to provide an overview of how digital signal process - ing has transformed radar system design and to give some insight into the techniques  and tradeoffs that a designer has to consider. 
 * *!&%)+* *    !#* (  !  *!%   '+(  , 
 In a digital  receiver, a single A/D converter is used to digitize the received signal, and digital  signal processing is used to perform the downconversion to I and Q baseband sig - nals. Continuing advances in sampling speeds are leading to sampling at increasing  frequencies, sometimes eliminating the need for a second downconversion, with the  possibility approaching of sampling directly at the radar RF frequency. The benefits  of IF sampling over conventional analog I/Q demodulation are ● Virtual elimination of I and Q imbalance ● Virtual elimination of DC offset errors ● Reduced channel-to-channel variation ● Improved linearity ● Flexibility of bandwidth and sample rate ● Tight filter tolerance, phase linearity, and improved anti-alias filtering ● Reduced component cost, size, weight, and power dissipation The use of a high IF frequency is desirable as it eases the downconversion and  filtering process; however, the use of higher frequencies places greater demands on  the performance of the A/D converter. 
 This method is used against frequency-agile systems whose rates are too fast to  follow or when the victim’s frequency parameters are imprecisely known. Jammer size is characterized by the effective radiated power ; ERP = GjPj, where Gj  is the transmit antenna gain of the jammer and Pj is the jammer power. Passive ECM  is synonymous with chaff, decoys, and other reflectors that require no  prime power. 
 V.(i.:AReviewofMicrowave Transistors forRadarApplication. NEREM Rec.,1974. rl.4.pp.116125. 
 Since loss of the focusing  magnetic field could cause the tube to fail, protective circuitry is normally employed to remove  the beam voltage in the event of improper focusing or the complete loss of focusing. The  collector of most high-power klystrons is insulated from the body (RF interaction circuit) of  the tube so as to allow separate metering and overload protection for the body current and tJlc  collector current.  Pulse modulation. 
 (1 1.3) follows from  the fact that the video signal-to-noise power ratio is equal to twice the IF signal-to-noise  power ratio (SIN), assuming a linear-detector law and a large signal-to-noise ratio.  If the rise time of the video pulse is limited by the bandwidth B of the IF amplifier, then  t, = l/B. Letting S = Elr and N = No B, where E is the signal energy, No the noise power per \  unit bandwidth, and r the pulse width, the error in the time delay can be written  112  T~ = (2 BE, N 0)  If a similar independent time-delay measurement is made at the trailing edge of the pulse, the  two combined measurements will be improved by $, or  * 112  = (4BE/No) rectangular pulse  For constant pulse amplitude A, the rms time-delay error given by Eq. 
 Conf  on Aeronaut. Electronics (Dayton, Ohio), pp. 291-295, 1958. 
 Radio Science, voi. 7, pp. 433-441, April, 1972. 
 This does not necessarily imply that a monostatic radar and a  bistatic radar viewing the same target ·will see the same cross section. In some cases the  monostatic cross section will be greater; in others, the bistatic cross section will be greater. But  on the average, the two will vary over comparable values. 
 BEAM TUBE HAS ALSO BEEN CONSIDERED FOR  THE TRAVELING WAVE TUBE   BUT IT IS NOT OBVIOUS WHETHER IT HAS ANY SIGNIFICANT ADVANTAGES  OVER THE -"+ 4RAVELING 7AVE 4UBE 474   4HE 474 LINEAR 
 The(3D ~nformation is obtained bythe.?eg~~~~~il:lL~<?~1!!li.~Lof asingle b~J.lllLas ~Q!!mared witli~ simultaneous ~!l~le beamsdescribed jntheabove.Arelatively simpleformofelectronic scaninthis application isfrequency scan(Sec.8.4)inwhichachangeinfrequency resultsinachangeof elevation angle.37.38Thebeamcanalsobescanned withphaseshifters.39 ~---~_.-----" Oneofthelimitations ofalong-range 3Dradarwithasinglescanning beamisthatthe angular coverage consists ofalargenumber ofindividual beampositions sothatthedwell tim~L£.lanyone resolution cellissmal\.The~ ineachp~itron Is determined bythetimeittakesfortheradarenergytotraveltomaximum rangeandback.The number ofbeampositions multiplied bythedwelltimeoreach equalsthescantime.Long dwelltimesandshortscantime(highdatarate)arenotcompatible. Forexample, assumethat a3Dradarwithaone-degree pencilbeammustcover20elevation beampositions and360 azimuth beampositions (atotalof7200beampositions) everyfourseconds.Ifthereisbutone pulseperbeamposition, thepulserepetition frequency canbenolessthan1800Hz,which corresponds toanunambiguous rangeof83km.Thisisarathershortunambiguous rangefor anair-surveillance radar.A3Dradarthatobtainsonlyollepulseperbeamposition cansuffer arelatively largebeam-shape loss.Generally 2or3pulsesarerequired asaminimum to reducethisloss.Also,onef2.l.!lse PCL~)~<lm position docs.HotaHowgowLM.:!.:.! processing~ makesdifficult theaccurate measurement ofelevation angle.ToobtainmorethailOile pulse perbeamposition and/orincrease theunambiguous rangerequircs somecompromises oran increase incomplexity. Thecompromises requircafatterbeamwidth oraslowerscanratc. 
 -UDIR  WHICH CONSISTS OF A  METER EAST TO WEST BY  METER NORTH TO SOUTH STONE ENCLOSURE 4HE WALLS ARE OF EXTREMELY CRUDE CONSTRUCTION  BUT MAS 
 (1936 –1941), BAC Washington (TNA AIR 20/1464).Airborne Maritime Surveillance Radar, Volume 1 1-6. IOP Concise Physics Airborne Maritime Surveillance Radar, Volume 1 British ASV radars in WWII 1939–1945 Simon Watts Chapter 2 ASV Mk. I and II 2.1 ASV Mk. 
 CODED RADAR '02 SYSTEMS THAT TRANSMIT AN IMPULSE AND RECEIVE THE REFLECTED SIGNAL FROM THE TARGET USING A SAMPLING RECEIVER CAN BE CONSIDERED TO OPERATE IN THE TIME DOMAIN '02 SYSTEMS THAT TRANSMIT INDIVIDUAL FREQUENCIES IN A SEQUENTIAL MAN 
 The dupiexer acts as a rapid switch to protect the receiver from damage when the high-power transmitter is on. On reception, with the transmit- ter off, the dupiexer directs the weak received signal to the receiver rather than to the transmitter. Duplexers generally are some form of gas-discharge device and may be used with solid-state or gas-discharge receiver protectors. 
 F. E. Churchill, G. 
 Interpolating  target angles within the beam is accomplished, as shown in Figure 9.10, by comparing  the phase of the signals from the antennas (for simplicity a single-coordinate tracker   is described). If the target were on the antenna boresight axis, the outputs of each   FIGURE   9.10  (a) Wavefront phase relationships in a phase comparison monopulse radar and ( b) block  diagram of a phase comparison monopulse radar (one angle coordinate) ch09.indd   11 12/15/07   6:07:14 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 l11t<'l'IIC1tio1111I Cm1fcn·11c·<' /U/UR-77. pp. JX4 390. 
 of codes 2 1 2 1 8 1 16 20 10 1 32 1 18 26 20 8 4 2 6 6 756 1021 1716 2 484 774 4 561 172 502 844 278 102 222 322 110 34 60 114Code (octal notation* for N > 13) 11,10 110 1101,1110 11101 110100 1110010 10110001 110101100 1110011010 11100010010 110100100011 1111100110101 36324 74665 141335 265014 467412 1610445 3731261 5204154 11273014 32511437 44650367 163402511 262704136 624213647 1111240347 3061240333 6162500266 16665201630 37233244307 55524037163 144771604524 223352204341 526311337707 1232767305704 2251232160063 4516642774561 14727057244044 . autocorrelation peak value and the same minimum peak sidelobe magnitude: 1110010, 0100111, 0001101, 1011000. For symmetrical codes, the code and its in- verse are identical. 
 K Barton, Radar Systems Analysis , Norwood, MA: Artech House, 1977. 23. A. 
 Suppose a prediction of median radar detec - tion performance is required for a specific month of the year and a particular sunspot  number or year of solar cycle. Analysis is initiated by selecting from the database a month that matches the  requirements. Individual backscatter ionograms are paired with the concurrent back - ground noise data and the ratio taken to yield a population of estimates of true sub- clutter visibility (SCV) for each frequency step, each beam, and each range bin. 
 This should dispose ofany hope that weshall beable todefine once and forallthe minimum detectable 1Theintermediate frequency itself isassumed tobehigh compared with (B,sothat itispermissible tospeak oftheinstantaneous power while actually meaning thepower averaged over onecycle oftheintermediate frequency. ‘The intervals sodefined areactually notentirely independent, fortheoutput power is,after all,acontinuous function ofthetime. Wearehere substituting fora continuous random process adiscrete random process, which iseasier todiscuss in elementary terms,. 
 reflector which is housed inawing nacelle inthe same fashion asthat oftheAN/APS-3. Asthis reflector isrotated at1200 rpm about anaxis passing through its feed and parallel tothe line offlight ofthe aircraft, the paraboloid is slowly tilted from aposition inwhich itsaxis coincides with the axis of rotation toaposition inwhich there isa60° angle between these axes. Because ofthepattern thus traced outinspace bythebeam (Fig. 
 The ratio vanes slowly forsmall elevation angles, then rapidly asthe lower lobe just touches theaircraft—in this case atanelevation angle of about 4°. Byestimating thesignal-strength ratio correct to10percent, theangle ofelevation canbetold with anaverage accuracy ofabout one- third degree, corresponding toaheight error at50miles of+1000 ft.. SEC. 
 This has been said to apply to stratiform rain. For  orographic rain Z = 31r1·71 and for thunderstorm rain Z = 486r1·37. Thus a single expres­ sion need not be used, and the choice of a Z-r relationship can be made on the basis of the type  of rain. 
 Y . Wu and P. Parikh, “High-power GaN HEMTs battle for vacuum-tube territory,” Compound  Semiconductor Magazine , January/February 2006. 
 If the signal were a pulse or some other radar waveform  with a spectrum of noninfinitesimal width, the simple Fourier integral which applies to a CW  sinc wavc would not give the correct radiation patter11 nor would it predict the transient  behavior. In most cases of practical interest the spectral width of the signal is relatively small,  with the conseqiletice that the pattern is not affected appreciably and the Fourier-integral  relatior~sl~ips arc satisfactoty al>ptoxiniatiotis. However, wlieti the reciprocal of tlic sigrial  bandwidth is comparable with the time taken by a radar wave to transverse the antenna  aperture, batldwidth effects can be irriportant and signal distortion may result. 
 3.9. Actual Complex Targets.—The actual targets encountered in thepractical useofradar areofamuchhigherdegrec ofcomplexity than the simple model just considered. Only arough estimate ofthe cross a) C9 FIG.37.-Enlarged frames ofaphotographic recording ofanA-scope trace. 
 FIELD CALIBRATION MUST BE PERFORMED TO KEEP THE ANTENNA WITHIN SPECIFICATIONS !CTIVE COM 
 Mantey, L. J. Griffiths, and B. 
 AES-10, pp.  779 787. Novemher. 
 DEPENDENT TRACKING ERRORS$YNAMIC LAG"EACON DELAY$YNAMIC LAG'LINT3CINTILLATION"EACON JITTER 0ROPAGATION ERROR !VERAGE TROPOSPHERIC REFRACTION )RREGULARITIES IN TROPOSPHERIC REFRACTION !VERAGE IONOSPHERIC REFRACTION )RREGULARITIES IN IONOSPHERIC REFRACTION  &ROM $ + "ARTON IN h-ODERN 2ADAR v 2 3 "ERKOWITZ ED  .EW 9ORK *OHN 7ILEY  3ONS    CHAP   P 4!",%    )NVENTORY OF 2ANGE 
 109. G. O. 
 The useful range of a search radar varies as the fourth root of the product of average RF power, antenna aperture area (which determines antenna gain), and the time allowed to scan the required solid angle of coverage (which limits how long the signal in each direction can be collected and integrated to improve signal-to-noise ratio): R4 * P x A x T (4.1) The range varies as the fourth root of power because both the outgoing trans- mitted power density and the returning echo energy density from the target be- come diluted as the square of the distance traveled. Trying to increase range by increasing transmitter power is costly: a 16-fold increase in power is needed to double the range. Conversely, negotiating a reduced range requirement can pro- duce remarkable savings in system cost. 
 s, 0.001 $180 bToreflector Tosearch AFCcrystalSearch-8eacon—( ToI AFCKi6AL5 V2* —— -’-%x 330k: L—— In6AG5 +%‘ii 0.01 2;0 Icon560 24k crystalfit1010k Ipf I,K1 10k I“ 20.11 *= mU.ulq+– –-. M-—120k 0.0130k 30k i6AS6 v,--- 750k ‘== 1.2k 16k switch-300V- FIG.12.21.—AFC forAN/APS-10 receiver.+I L o -1––----JLI 560 0.05 24k 6;G5.I6 180k +. 470 THE RECEIVIArG SYSTEM—RADAR RECEIVERS [SEC. 
 Although itispossible touseasingleradarforboththesearchandthctracking functions, such. a ~vowdirre irs11;iIly results iri certain operatiorial limitations. Obviously, when the radar is  uzcd in its trackilig mode, it Iias rio knowledge of otlier poteritial targets. 
 523-526 Homeonjam,549 Huggins phaseshifter.303-305 Hybrid-coupled phaseshifter.289 IAGC,488 Ice: onantennas, 240 onradomes, 269 sea.481-482 Icespheres, scattering from,502 Idealobserver, 380 IFcancellation, MTI,126 Imagefrequency, ofmixer.347 Image-recovery mixer,349 Improvement factor,MTI: antenna scanning, 134-136 antenna sidelobes, 145 clutternuctuations, 131-134 defined, 111,129 equipment instability, 130-131 limiting, 136-138 quantization, 120. Incidence angle, 473  Index of refraction, for air, 448  Insects, 510  Integration improvement factor, 30-31  for Swerling models, 49  Integration loss, 30-33  Integration, of radar pulses, 29-33  Integrators, 388-392  Interclutter visibility, 130, 494-495  Interferometer:  in height finding, 545  radar, 165  Intermediate-frequency receiver, CW radar, 74  Interrupted CW (ICW), 147  Inverse probability receiver, 377-379  Inverse SAR, 528-529  Inverse scattering, 437-438  Inverted coaxial magnetron, 195  Ion oscillations, 74  Ionosphere, 530  IREPS, 456  Isolation, in CW radar, 71-73  in FM-CW radar, 88-91  Kalman filter, 185  Kalmus clutter filter, 497  Keep-alive, in TR tube, 362-363  Klystron amplifier, 200-205  Knife-edge ambiguity diagram, 41 8-419  Lambert surface, 497  Land clutter, 489-498  at millimeter wavelengths, 563  Laser radar, 564-566  Latching ferrite phase shifters, 293-294  Lens antennas, 248-254  Lens array, 308-309  Letter-band nomenclature, 8  Likelihood-ratio receiver, 377, 379  Limited-scan arrays, 334  Limiting, in MTI, 136-138  Limiting loss, 59  Lin-log receiver, 507  Linear array, 279  Linear beam tubes, 200-208  Linear FM pulse compression, 422-427  Linear recursive sequences, 429  Line-of-sight stabilization, 270  Line-type modulator, 214-215  Loaded-line phase shifter, 289  Lobe recognition, in height finding, 546  Lobe switching, 153  Lobing, due to multipath, 442-447 Log-FTC, 506-507  and sea clutter, 486-488  Log-log.receiver, 486-488  Log normal probability density function, 51  and sea clutter, 479  Logarithmic detector, 384  LORO, 159  Loss, integration, 30-33  Losses, system, 56-6 1  Low-angle tracking, 172- 176  Low-noise front ends, 351-353  Low-sidelobe antenna, 227-228, 333, 549  Luneburg lens, 252-253  m-out-of-,I detector, 388-390, 486  Magnetron, 192-200  Man, radar cross section of, 44  Matched filter, 5, 16, 369-375  in FM-CW radar, 91-92  Maximal length sequences, 429  Maximum unambiguous range, 2-3  Measurement accuracy, 400-41 1  Median detector, 486  Metal-plate lens, 250-252  Metal space-frame radome, 266  Metallic radomes, 268  METRRA, 437  Microwave radiation hazards, 465-466  Microwave refractometer, 455  Mie region, 34  Millimeter wave radar, 560-564  Minimum detectable signal, 16- 18  Mirror-scan antenna, 242-244  Mixer-matrix feed, 305, 308  Mixers, 347-35 1  Modulating anode, 201, 203  Modulators, 2 14-216  Module, solid-state, 2 17-21 8  Monopulse radar, 160-167, 182-183  in height finding, 543  and high-range-resolution, 18 1 - 182, 435  Monostatic radar, 553  MOPA (master-oscillator power amplifier), 106  MOSAR, 315  Motor drives, for antennas, 273  Moving Target Detecior, 127-129  Moving target indication (see MTI)  Moving-window detector, 184, 388-390  MTD, 127-129  MTI radar, 101-148  acoustic delay line, 126  A/D converter, 120  adaptive, 142  576INDEX Incidence angle,473 Indexofrefraction, forair,448 Insects,510 Integration improvement factor,30-31 forSwerling models,49 Integration loss,30-33 Integration, ofradarpulses,29-33 Integrators, 388-392 Interclutter visibility, 130,494-495 Interferometer: inheightfinding,545 radar,165 Intermediate-frequency receiver, CWradar,74 Interrupted CW(ICW),147 Inverseprobability receiver, 377-379 InverseSAR,528-529 Inversescattering, 437-438 Inverted coaxialmagnetron, 195 Ionoscillations, 74 Ionosphere, 530 IREPS,456 Isolation, inCWradar,71-73 inFM-CW radar,88-91 Kalman filter,185 Kalmusclutterfilter,497 Keep-alive, inTRtube,362-363 Klystron amplifier, 200-205 Knife-edge ambiguity diagram, 418-419 Lambert surface,497 Landclutter, 489-498 atmillimeter wavelengths, 563 Laserradar,564-566 Latching ferritephaseshifters,293-294 Lensantennas, 248-254 Lensarray, 308-309 letter-band nomenclature, 8 Likelihood-ratio receiver, 377,379 Limited-scan arrays,334 Limiting, inMTI,136-138 Limiting loss,59 Lin-logreceiver, 507 Lineararray,279 Linearbeamtubes,200-208 LinearFMpulsecompression, 422-427 Linearrecursive sequences, 429 Line-of-sight stabilization, 270 Line-type modulator, 214-215 Loaded-line phaseshifter,289 Loberecognition, inheightfinding,546 Lobeswitching, 153 lobing,duetomultipath, 442-447Log-FTC, 506-507 andseaclutter,486-488 Log~log.receiver; 486-488 Lognormalprobability densityfunction, 51 andseaclutter,479 Logarithmic detector, 384 LORa, 159 Loss,integration, 30-33 Losses,system,56-61 low-angle tracking, 172-176 Low-noise frontends,351-353 Low-sidelobe antenna, 227-228, 333,549 Luneburg kns,252-253 J m-out-of-Il detector, 388-390,486 Magnetron, 192-200 Man,radarcrosssectionof,44 Matched filter,5,16,369-375 inFM-CW radar,91-92 Maximal lengthsequences, 429 Maximum unambiguous range,2-3 Measurement accuracy, 400-411 Mediandetector, 486 Metal-plate lens,250-252 Metalspace-frame radome, 266 Metallic radomes, 268 METRRA,437 Microwave radiation hazards, 465-466 Microwave refractometer, 455 Mieregion,34 Millimeter waveradar,560-564 Minimum detectable signal,16-18 Mirror-scan antenna, 242-244 Mixer-matrix feed,305,308 Mixers,347-351 Modulating anode,201,203 Modulators, 214-216 Module, solid-state, 217-218 Monopulse radar,160-167, 182-183 inheightfinding,543 andhigh-range-resolution, 181-182, 435 Monostatic radar,553 MOPA(master-oscillator poweramplifier). 106 MOSAR,315 Motordrives,forantennas, 273 MovingTargetDetector, 127-129 Movingtargetindication (seeMTI) Moving-window detector, 184,388-390 MTD,127-129 MTIradar,101-148 acoustic delay line,126 AIDconverter, 120 adaptive, 142. 
 BAND SPURIOUS OUTPUT CAN ALSO OCCUR IN SOME CATHODE 
  DOWNWIND AND CROSSWIND BEHAVIOR OF SEA CLUTTER AT VERY LOW GRAZING ANGLES %XAMPLES OF CLUTTER BEHAVIOR AT THESE VERY LOW ANGLES MAY BE FOUND IN INDEPENDENT  MEASUREMENTS AT RELATIVELY HIGH WIND SPEEDS BY (UNTER AND 3ENIOR OFF THE SOUTH COAST OF %NGLAND  AND BY 3ITTROP OFF THE WEST COAST OF .ORWAY 4HEIR RESULTS FOR ORTHOGONAL  DIRECTIONS RELATIVE TO THE WIND ARE SHOWN IN &IGURE   ALONG WITH THE PREDICTIONS OF A CONVENTIONAL SHADOWING FUNCTION  AND THE THRESHOLD 
 GAIN JAMMING AND 2'0/ ARE COMBINED IN MANY CASES TO COUNTER CONICAL 
 ETER MEASUREMENTS    ESPECIALLY OVER SEA ICE 4HE %NVIRONMENTAL 2ESEARCH )NSTITUTE  OF -ICHIGAN %2)-   ##23  THE %UROPEAN 3PACE !GENCY %3!   AND THE   *ET 0ROPULSION ,ABORATORY *0,  USED IMAGING SYNTHETIC APERTURE RADARS 3!2S  FOR  SOME SCATTERING MEASUREMENTS  BUT MOST WERE NOT WELL CALIBRATED 3INCE THE ADVENT OF SPACEBORNE 3!2S 3)2 !  "  AND # %23  AND  2ADARSAT %NVISAT *%23 
 Higher than desired frequency-dependent  phase and amplitude ripple may result from improper use of this configuration. A splitter and combiner network may also provide serial isolation among cas - caded amplifier stages as well as parallel isolation. For example, when a Class-C  biased transistor is pulsed, it passes through its cutoff, linear, and saturation regions. 
 IT-4,  pp, 50-52, March, 1958.  45. Hansen, V. 
 The1;.S..irmy referred tothis material as“chaff”; theGermans called it“Dueppel. ”. SEC.310] COMPO1’A’D TARGETS 83 The quantity inparenthesis inEq. 
 But for effective dis-  play on the CRT the pulse may not be ‘square’ enough.  To produce a good vertical leading or lagging edge to the  pulse, for accurate CRT reading, we may need to distort  the received signal, to ‘square it up,’ and for this purpose  we may put the signal through a ‘pulse-shaper.” But an  essential part of the receiver is not involved in the con-  tinuous chain of reception. We gain nothing by receiving  the pulse and displaying it on a CRT unless we can  relate the pulse in time to the time of the transmitted  energy. 
 AMPLIFIERS  FOR RADAR APPLICATIONS v )%%% 4RANS VOL 03 
 TO 
  TO  .KFT  TO  -KM OR  TO  -KFT 3TANDARD 
 The screen material has anatural color much like that ofthe. 550 THE RECEIVING SYSTEM-INDICATORS [SEC. 1321 phosphorescent light, sothatcontrast isreduced byreflectedhght. 
 BAND MONOPULSE CAPABILITY  '(Z AND  '(Z BANDS  4HE OBJECTIVE INCLUDED HIGH 
 2 was based on the envelope detector.  The envelope detector consists of a rectifying element and a low-pass filter to pass the  modulation frequencies but to remove the carrier frequency. The rectifier characteristic relates  the output signal to the input signal and is calledbthe detector law. 
 DELAY CANCELER REQUIRES THE BEST MATCH BETWEEN THE ACTUAL PATTERN AND THE REQUIRED PATTERN NEAR BORESIGHT  WHEREAS DOUBLE CANCELLATION REQUIRES THE BEST MATCH .   !)2"/2.% -4)  Î°£Ç ON THE BEAM SHOULDER 3TEP 
  
 Natl. Bur. Std.,  vol. 
 Such windows play the same role incoupling cavities towaveguide asdocoupling loops for coaxial line. On10-cm systems using waveguide, theinput coupling may be bymeans ofaniris, and theoutput by acoupling loop. Switches exactly like TR switches with theoutput coupling omitted may beused asATR switches. 
 (This series of papers was  awarded the 1996 M. Barry Carlton Award; see IEEE Transactions on Aerospace and Electronic  Systems , vol. 35, no. 
 BASED MICROWAVE IMAGERS ARE SYNTHETIC APERTURE RADARS WITH THE EXCEPTION OF CERTAIN EARLY 3OVIET OCEAN 
 In the dielectric exist the corresponding components E 2tan  and E 2norm .   The following applies for the instantaneous values at the interface:   € e1tan=e2tan,  € e1norm=εr⋅e2norm (2.18)   The tangential electric field strengths are constant at the interface and the orthogonal electric field  strengths undergo a shift or “jump” in the transition at the interface.  When the dielectric is void of magnetic effects (t hus µ r = 1), the magnetic field strengths pass unchanged through the inte r- face. 
 Jones, “Paraboloid reflector and hyperboloid lens antenna,” IRE Trans ., vol. AP-2,   pp. 119–127, July 1954. 
 9. Van Vleck, J. H., and D. 
   PP n  3EPTEMBER   7 $ "URNSIDE  - # 'ILREATH  " - +ENT  AND ' , #LERICI  h#URVED EDGE MODIFICATION OF  COMPACT RANGE REFLECTOR v  )%%% 4RANS  VOL   !0 
 9  2.3 Reflection on Dielectric Interfaces .................................................................................. 10  3 The Radar Equation ............................................................................................................. 13  3.1 Radar Equation for Point Targets .................................................................................... 
   30!#% 
 LeCun, Y.; Bottou, L.; Orr, G.; Müller, K.R. Efﬁcient BackProp. In Neural Networks: T ricks of the T rade ; Orr, G., Müller, K., Eds.; Lecture Notes in Computer Science: Heidelberg, Germany, 1524. 
 8 In this example the periods are in the ratio 25: 30: 27: 31 and the first blind speed is  28.25 times that of a constant prf waveform with the same average period. If the periods of the  staggered waveforms have the relationship n1 /T1 = n1 /T1 = · · · = nN /TN, where ni, n1 •.•. , nN  are integers, and ff VB is equal to the first blind speed of a nonstaggered waveform with a . 
 The result is that  the phase of the target remains constant, but the phase of many of the spurious signals  varies from pulse to pulse. In this type of configuration, signal isolation and frequency  architecture is critical to minimize the occurrence of spurious signals that could erro - neously be interpreted as false targets. COHO and Timing Instability. 
 X+D  --X Scan  reference  ~~ Phase  comp  Scon  detector  Magnelran SCR 1584  servo system  Narrow !rock- ing fiHer -+fi,_._  Speed  gate  X Tt\L  I  XTAL  Pedestal control CW AND FRE()lJENCY-MODUl.ATFD RADAR RI  lkHz 30kHz M  Doppler  amplifier  Bolonced  mixer  Signal IF  ~ AFC  Reference  IF  Figure 3.9 Block diagram of a CW tracking-illuminator.31 (Courtesy IEEE.)  discrimination of a CW radar allows operation in the presence of clutter and ,has been well  suited for low altitude missile defense systems. A block diagram of a CW tracking illuminator  is shown in Fig. 3.9. 
 LOOK COMPLEX 3,#  PRODUCTS 4HESE DATA RETAIN THE FULL RESOLUTION OF THE RADAR  AND MOST IMPORTANT  RETAIN THE RELATIVE PHASE OF THE BACKSCATTERED FIELD "Y  DEFINITION  3,# FILES ARE IN AMPLITUDE AND PHASE  OFTEN REPRESENTED AS AN ARRAY OF IN 
 In the extreme, when the target passes directly overhead, the azimuth drive would have to flip the antenna 180° at the instant when the target crosses overhead. This effect requires the azimuth- tracking loop gain to change approximately as the secant of elevation angle in order to maintain essentially constant overall azimuth loop gain. In practical tracking radars with the conventional elevation-over-azimuth mount the elevation angle is typically limited by this effect to a maximum of 85° since the servo band- width required for higher elevation angles exceeds practical limits. 
 SOURCE TARGET AS A FUNCTION OF RELATIVE PHASE  E FOR DIFFERENT  VALUES OF RELATIVE AMPLITUDE A MEASURED WITH A TRACKING RADAR &IGURE  FROM (OWARD     2ADIUS 
 DWELL STAGGERING IS USED WITH -4$ FILTER BANK  PROCESSING &OR MANY -4) APPLICATIONS PULSE 
 2544 A vol 1, November 1943 (TNA AIR 10/3286) [8] ASV Equipment and Ancillaries, chapter 12 ASV Mk. II ARI 5136, including Box, Aerial Coupling, Type 8, S.D. 0205, Air Ministry, February 1943 (TNA AIR 10/3984) [9] A Review of ASV Performance, ORS/CC Report 201, 23 June 1942 (TNA AIR 15/609) [10] Report on Prototype Installation of ASV Mk. 
 55. M. Kerker, M. 
 IRE. vol. 21. 
 DIGITAL !$  CONVERSION MUST PRESERVE THE LINEARITY OF AMPLITUDE AND PHASE OVER THE REQUIRED DYNAMIC RANGE  HAVE A SMALL EFFECT ON OVERALL RADAR SYSTEM NOISE TEMPERATURE  AND BE FREE FROM UNDESIRED SPURIOUS RESPONSES !DVANCES IN !$ CONVERTER TECHNOLOGY IS NOW MAKING IT POSSIBLE  TO DIRECTLY CON 
 When the radiation is at some angle other than ,.  broadside. the radiation pattern is a conical-shaped beam. 
 70-77, April, 1974.  RADAR CLUTTER 513 24.Croney.J..andA.Woroncow: Dependence ofScaClutterDecorrelation Improvements UponWave Height. 1EElilt.COII(0I1Adl lallcesillMar;lIeNav;gat;ollaIAids. 
 S4 is the average sidelobe level. (From Wiiley,5(> courtesy of Bendix Radio.)(a)RELATIVE POWER (dB) . the elements are used, the gain of the array will drop by 10 dB. 
 During acquisition, the radar must look at the region between  transmitter pulses, and upon initial acquisition, it closes the range- and angle-track - ing loops without resolving the range ambiguity. The next step is to find which range  interval, or between which pair of transmit pulses, the target is located. The zone n is  determined by coding a transmit pulse and counting how many pulses return before  the coded pulse returns. 
 RADAR INTERFERENCE AND  THE NEED FOR FREQUENCY ARBITRATION .OISE -ODELS  4HE WIDELY USED REFERENCE ON NOISE IS THE )NTERNATIONAL 2ADIO  #ONSULTATIVE #OMMITTEE ##)2  2EPORT   4HIS REPORT IS BASED UPON MEA 
 .......................  6  Maximum Unambiguous Range  ................................ ................................ 
 AIR RADARS RECEIVE ENERGY BACKSCATTERED FROM REFRACTIVE INDEX INHO 
 This keeps the aperture busy and responsive to the latest activity requests.  Following the selection of the antenna job by the scheduler, the front-end (transmit and  receive) hardware is configured, and in-phase and quadriture (I/Q) data is collected and  sent to the signal processors. There, the data is processed in a manner defined by the  sensor mode, and the signal processing results are returned to the client that requested  them. 
 Ê 
 When the radar  resolution is suniciently small it is found that the sea echo is not spatially uniform, but is  composed or"occasional" individual targellike echoes of short duration that result in a spiky  appearance on a radar display. On an A-scope display it is found that $ea clutter appears more  spiky ror horizontal than ror vertical polarization, when the radar looks up or downwind  rather than crosswind, at low radar frequencies rather than for high, and for low grazing angles  rather than for high grazing anglcs.7 To resolve the individual spikes the' radar pulse width  should he several tens of nanoseconds rather than microseconds. An individual spike might  have a radar cross section at X hand of the order of magnitude of one square meter (more  or less). 
 (9.3) governing the SLC is immediately recognized. With respect to SLC, adaptive array techniques offer the capability of enhanc- ing the target signal while canceling the disturbance. The adaptive system allo- cates in an optimum fashion its degrees of freedom (i.e., the set of received FIG. 
 888-893, September, 1947.  5. Saunders, W. 
 5.2. T emporal Deformation Characteristics over Feature Points In order to further investigate the temporal variation characteristics of deformation, two feature points (CT1 and CT2) were selected for analysis (the locations are shown in the ﬁrst image of Figure 9), with comparison to the results obtained through the pure linear model (see Figure 10). CT1 was located in the bottom area of the image, where the subsidence was quite obvious (with an accumulated subsidence up to 185 mm), whereas the maximum subsidence in the linear velocity model was only 47 mm. 
 35. G. J. 
 NIQUES WITH MULTIPLE RECEIVERS TO PROCESS THE AMPLITUDE AND PHASE DIFFERENCES OF THE ECHO STRUCTURES AS THEY TRANSLATE OVER TWO ADJACENT ANTENNAS USUALLY SUBARRAYS OF THE SAME ARRAY ANTENNA  TO MEASURE COMPONENTS OF THE HORIZONTAL OR TRANSVERSE WIND  )N THIS MANNER  TWO ORTHOGONAL SUBARRAYS CAN MEASURE COMPONENTS OF THE  HORIZONTAL WIND USING CROSS 
 BASED 3!2S 3EASAT ILLUSTRATES SEVERAL  CHARACTERISTICS OF MANY CIVILIAN %ARTH 
 pp. 98 102. January. 
 The magnetron is connected to the antenna via a duplexer and a rotating joint.  The magnetron has a typical operational life of about 10,000 hours and is by far the  lowest lifed component in the whole system. The duplexer is nowadays a three- or  four-port ferrite circulator. 
 SPEED )& SAMPLING  IT IS ALSO POSSIBLE TO DIGITIZE BOTH SIGNALS SIMULTANEOUSLY USING A SINGLE !$ CONVERTER AND PERFORM THE FREQUENCY SEPARATION USING DIGITAL SIGNAL PROCESSING 7HICHEVER APPROACH IS USED  CARE MUST BE TAKEN TO PROVIDE ADEQUATE DYNAMIC RANGE AND LINEARITY TO PREVENT INTERMODULA 
 The magnetron oscillator, however,  has been used in some short or medium range radars and in the widely popular civil  marine radar (Chapter 22), which requires only a small power transmitter and has no  need for MTI capability. 10.2 LINEAR-BEAM AMPLIFIERS2 The klystron, TWT, and hybrids of the two have been important sources of RF power for  many successful radar systems. The electrons emitted from the cathode are formed into  a long cylindrical beam that receives the full potential energy of the electric field before  the beam enters the microwave interaction region. 
 The 2D focusing and image registration are the basics of the proposed method. We assumed that the variation in the heights of the targets in the scene was less than the resolution in elevation (see Equation (9)), so the imaging area could be seen as e ﬀectively ﬂat. Thus, the targets in the same 2D image cell cannot be separated in elevation after elevation processing. 
 FACE CORPORATE 
 2.56 Clutter  ...............................................................  2.57  Targets in Clutter  ...............................................  2.57  2.9 Cumulative Probability of Detecti on  ........................ 
 12-10 isordinarily used (see Sec. 13.6). Itschief advantage is that itcan bedirect-coupled. 
 ARRIVAL SPECTRUM OF THE RECEIVED SIGNAL  CAN BE COMPUTED USING THE MULTIPLE SCATTERING THEORY OF !NDERSON ET AL  &)'52%   #URVES OF PROPAGATION LOSS VERSUS RANGE  AS USED FOR ESTI 
     
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.64  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18  6. C. 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 24.64  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 120. U. 
 This process virtually eliminates the image response problem, allowing the use  of a single RF filter spanning the entire operating bandwidth. Narrow bandwidth filter - ing can be used on the high IF as defined by the signal bandwidth before downconver - sion to a lower IF for digitization or baseband conversion. IF filtering is the primary filtering used to define the receiver bandwidth prior to A/D  conversion in receivers using either IF sampling or baseband conversion. 
 D. Pidhayny of the Aerospace  Corporot iort.)  TRACKING RADAR179 fluctuations oftheinputsignalbyfilteringorsmoothing. Therefore, thetracking bandwidth shouldbenarrowtoreducetheeffectsofnoiseorjitter,rejectunwanted spectral components suchastheconical-scan frequency orenginemodulation, andtoprovideasmoothed outputof themeasurement. 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.44  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 distribution changes shape, becoming somewhat rectangular with a separation of  aircraft as in Figure 9.31 b. At the widest separation, where the aircraft are almost  resolved, as in Figure 9.31 c, the radar will track one aircraft until it fades and the  other aircraft blossoms in amplitude. 
 These added M sam- ples are filled with zeros in the reference waveform FFT. For extended range coverage, repeated correlation processor operations are required with range de- lays of M samples between adjacent operations. This correlation processor can be used with any waveform, and the reference waveform can be offset in doppler to achieve a matched filter at this doppler. 
 This is referred to as the displaced phase center antenna (DPCA) technique.7"11 Physically Displaced Phase Center Antenna. In physical DPCA,10'11 theDOUBLE DELAY SINGLE DELAYIMPROVEMENT FACTOR (dB) . apertures of two side-looking antennas are aligned parallel with the aircraft longitudinal axis. 
 Stochastic Gradient Descent with Momentum Gradient descent is a commonly used optimization algorithm for neural network which can solve many simple problems. However, when the training dataset is very large, we can ﬁnd that using simple gradient descent method may consume much computing resources, and the convergence process will be slow. At the same time, since all the training data are considered for each calculation in gradient descent method, it may cause over-ﬁtting. 
 ( a) Scanning frame and probe; ( b) optical picture of ﬁve balls; ( c) distribution of target spatial position. Figure 15is the optical pictures of the measurement system and target distribution. Figures 16and 17show imaging results by applying the two approaches provided with complete data and compressed sampling data. 
 Not shown inthe transmitter diagram isamonitor, consisting ofa crystal mixer and avideo amplifier, which draws power from the main waveguide. Incombination with asynchroscope, this provides avery effective means ofchecking and aligning thetransmitter. R~fll~D-c wltageamplifier Microwatie Reference discriminator +(cavity ( E TransmitterlMb directional couplerAntenna )I Mixer l-famplifierAutomtic 77Video gaincontrol amplifier Manual Receiver gainmntrol Signals FXQ.17.19.—Microwave equipment. 
 On the other hand, the flat, singly curved and doubly  curved surfaces of electrically large targets all give rise to different echo characteristics.  Reentrant structures such as jet engine intakes and exhausts generally have large  echoes, and even the trailing edges of airfoils can be significant echo sources. The radar cross sections of simple bodies can be computed exactly by a solution of  the wave equation in a coordinate system for which a constant coordinate coincides  with the surface of the body. 
 J. Serafin, C. L. 
 25, 1955.  55. Spaulding, A. 
 This suggests that although the chine concept may have worked for the fuse - lage of the fabled Mach-3 SR-71, it is by no means a viable approach for reducing the  echoes from wing leading edges. Indeed, the designers of the B-2 airframe apparently recognized early in the design  work that it would be nearly impossible to reduce the leading edge RCS of their sub - sonic airframe to acceptable levels. That being the case, they decided to angle all  leading and trailing edges at a common sweep angle: 34 °. 
 MAND TO THE FIRST INTEGRATOR DEFINES THIS QUADRATIC PHASE FUNCTION 4HE DIGITAL COMMAND TO THE SECOND INTEGRATOR IS THE OUTPUT OF THE FIRST INTEGRATOR PLUS THE DESIRED CARRIER FREQUENCY 4HIS CARRIER MAY BE DEFINED BY THE INITIAL VALUE OF THE FIRST INTEGRATOR 4HE DESIRED INITIAL PHASE OF THE WAVEFORM IS THE INITIAL VALUE OF THE SECOND INTEGRATOR OR ELSE MAY BE ADDED TO THE SECOND 
 This is an interesting formula as it shows that when AF^, is constant, as it is with many klystrons, the correlated noise power is independent of frequency and di- rectly dependent on range. A convenient curve which gives the ratio of noise at the receiver to measured noise on the transmitter (Fig. 14.2) is based on the approximations of formulas (14.2) and (14.3). 
 6, pp. 198-206, Nov., 1967.  118. 
 Copyright ª2018 Morgan & Claypool Publishers All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the publisher, or as expressly permitted by law orunder terms agreed with the appropriate rights organization. Multiple copying is permitted inaccordance with the terms of licences issued by the Copyright Licensing Agency, the CopyrightClearance Centre and other reproduction rights organisations. 
 Mass..1975.(Acollec­ tionof38reprints onsca.land,andatmospheric c1uller.) 37.Daley.JC..WT.Davis.J.R.Duncan, andM.B.Laing:NRLTerrain ClutterStudy.PhaseII. Nal'ClIRescarch La!Joratorj' Rcport6749,Washington, D.C.,Oct.21,1968. ~X.Katz.I..andL.M.Spctncr: Polarization andDepression-Angle Dcpendence ofRadarTerrain Return.J.Rcs.Nat.Bill'.Stds.,vo/.64D,pp.483-486, Septembcr/October, 1960. 
 F. Lyons: Receivers with Zero Intermediate Frequency, Proc. I RE, vol. 
 97. Flad. E. 
  
 |  In practice the translucent screen can be several feet  in diameter, and the ‘picture’ is projected through a  lens-and-condenser system. The tube screen turns a  - darkish purple under the impact of the electron beam, ,  . ON THE SCREEN 69  and returns to its normal greyish colour when the beam  has moved on and it is subject again only to the heat of  the associated high-density light source. 
 The scenario image of the side-looking beam processed by the above imaging algorithm is shown in Figure 12a, the position of the center point target is (1025, 2050), and the positions of the remaining four points are (1025 ±135, 2050 ±120). The distance between the center point target and the rest of the point target in the azimuth direction is 135/1.35 ×0.3 = 30 m, and the distance between the center point target and the rest of the point target in the range direction is 120/1.2 ×0.3 = 30 m, which is consistent with the scenario layout. Figure 12b is a result of interpolation of the point (1025 −135, 2050 −120) in Figure 12a. 
 £ MIN[ ;      =  ]   QQ S M M    WHERE NJ IS THE NUMBER OF $& DETECTIONS OVERLAPPING THE TIME INTERVAL FOR WHICH THE  JTH RADAR TRACK EXISTS  PETI  IS THE $& DETECTION AT TIME  TI PJTI  IS THE PREDICTED AZIMUTH  OF RADAR TRACK  J FOR TIME  TI AND THE FACTOR  LIMITS THE SQUARE ERROR TO  R TO ACCOUNT FOR  $& OUTLIERS "Y USING THE TWO LARGEST 0JS  DESIGNATED 0MAX AND 0NEXT  AND THRESHOLDS  4,  4(  4-  AND 2  THE FOLLOWING DECISIONS AND DECISION RULES WERE GENERATED   &IRM CORRELATION  $& SIGNAL GOES WITH RADAR TRACK HAVING LARGEST  0J IE  0MAX   WHEN 0MAX q 4( AND 0MAX q 0NEXT   2   4ENTATIVE CORRELATION   $& SIGNAL PROBABLY GOES WITH RADAR TRACK HAVING LARGEST  0J  IE  0MAX  WHEN 4(   0MAX q 4- AND 0MAX q 0NEXT   2   4ENTATIVE CORRELATION WITH SOME TRACK   $& SIGNAL PROBABLY GOES WITH SOME RADAR  TRACK BUT CANNOT DETERMINE WHICH  WHEN 0MAX q 4- BUT 0MAX   0NEXT   2   4ENTATIVELY UNCORRELATED   $& SIGNAL PROBABLY DOES NOT GO WITH ANY RADAR TRACK  WHEN 4-   0MAX   4,   &IRMLY UNCORRELATED  $& SIGNAL DOES NOT GO WITH ANY RADAR TRACK WHEN 4, q 0MAX. 
 However, its  range accuracy was superior to that obtained with optical methods. The SCR-268 remained  the standard fire-control equipment until January, 1944, when it was replaced by the SCR-584  microwave radar. The SCR-584 could control an antiaircraft battery without the necessity for  searchlights or optical angle tracking .. 
 80. Buchner, M. R.: A Multistatic Track Filter with Optimal Measurement Selection, IEE Radar Conf., pp. 
 TIONS "ECAUSE &)2 FILTERS REQUIRE NO FEEDBACK  THEY ARE EASIER TO USE IN VERY HIGH 
 When itisdesired. SEC. 6.12] HEIGHT-FINDING WITH AFREE-SPA GE BEAM 189 tofind height onatarget, the antenna isstopped and manually kept pointed inthe target azimuth. 
 10.7 for achieving CFAR. One example suitable for a clutter environment is the adaptfoe  video threshold (AVT) which sets the threshold according to the amount of clutth (or noise)  in a number of range cells ahead of and behind the particular range cell of interest. This form  of CFAR is popular in automatic detection and track (ADT) systems since it is not strongly  dependent on the type of clutter and can provide CF AR with land and weather clutter as well  as sea clutter. 
 PLANE REAL AXIS AT         
 MENTS WHOSE RANGE IS GREATER THAN THE AVERAGE RANGE OF MEASUREMENTS WITH 3.2  HIGHER THAN THE DETECTION THRESHOLD . 
 Blank, or empty, bins occur when the unfolded range  falls outside a particular coarse bin interval. Key advantages to this approach are the  ability to change the range correlation window dynamically and perform motion com - pensation easily for the range change across the dwell due to radar platform motion  and/or the target’s motion (if the unambiguous doppler has been resolved prior to this  process). Additionally, the range gate sizes do not need to stay the same across the  set of PRFs used in the dwell; in this case, the ambiguous range gate measurements  on each look are first converted to common distance units (e.g., meters) prior to the  unfolding and scanning/correlation processes. 
 J. W. Taylor, Jr. 
 Headrick, “Comparison of RADARC High-frequency radar performance  prediction model and ROTHR Amchitka data,” Naval Res. Lab. Rept . 
 Telford: Estimation of Tropospheric Refractive Bending from Atmos-  pheric Emission Measurements. Radio Sciertce, vol. 8, pp. 
 ornonstandard. propagation appliestoanyoftheabovepropagation conditions otherthannormal; butitisalmostalways usedtodescribe thoseconditions wheretheradarrangeisextended wellbeyondnormal. Asuperrefracting ductwhichliesclosetothegroundiscalledaground-based duct.ora swfaceduct.Overwaterthesurfaceductisalsocalledtheevaporation duct,sinceitistheresult ofwatervaporevaporated fromthesea.Aductwhichliesabovethesurfaceiscalledan elevated duct.Surfaceductsapparently aremoreusualthanelevated ducts.Topropagate energywithintheduct.theangletheradarraymakeswiththeductshouldbesmall.usually lessthanonedegree.26•27Onlythoseradarrayslaunched nearlyparalleltotheductare trapped. 
 TIME CONVOLUTION IS DONE IN THE TIME DOMAIN BY CONVOLUTION OF THE COMPLEX ENVELOPE INPUT SEQUENCE FOLLOWING DIGITAL DOWN 
 ING DESCENDING PASSES IN COORDINATION WITH THE OPTICAL SENSORS  AND ALSO EXCEPTING EXTRAORDINARY )N3!2 AND MARINE APPLICATIONS AT NONSTANDARD INCIDENCE AND RECURRENT REPEAT 
 K. Johnson, “Magellan imaging radar mission to Venus,” Proceedings of the IEEE , vol. 79,  pp. 
 Theconicalsca'noftheSCR-584 wasoperated duringthesearchmode andwasactually aPalmerscaninahelix.Ingeneral, conicalscanisperformed duringthe searchmodeofmosttracking radars. ThePalmerscanissuitedtoasearchareawhichislargerinonedimension thananother. Thespiralscancoversanangularsearchvolumewithcircularsymmetry. 
 is not found at zero freqt~ency as is the case for land backscatter, but is centered at two discrete  frequencies symmetrically spaced around zero, Fig. 14.8. The sea may be thought of as  composed of a large number of individual wave trains, each with a differcnt wavelength and  amplitude and traveling In different directions. 
  
 where crh = standard deviation of surface height variations X = wavelength Since this proportion is down to 13.5 percent when vh = X/2ir and to 1.8 percent when vh = X/(2irV2), significant specular reflection is seldom found for the centi- meter wavelengths usually used for radar. Nevertheless, a simplified model like this is convenient for some purposes. Observation of reflected sunlight from rippled water, from roads, and from other smooth surfaces leads to the postulation of a facet theory.34'35 The only sunlight reaching the observer from smooth surfaces such as water is that from facets for which angle of incidence equals angle of reflection. 
 350 THEMAGNETRON AND THEPULSER [SEC. 105 ispresented tothemagnetron and varied inphaseoveratleastafullhalf cycle (see Fig. 10”17). 
 4(% 
 SURFACE MODELS 4HEORIES BASED ON SCATTERING BY SURFACE FEATURES HAVE BEGUN TO SHOW PROMISE  AND AT LEAST ONE OF THESE FEATURESTHE BREAKING WAVE AT VARIOUS SCALES  MACRO TO MICROIS INCREASINGLY RECOGNIZED AS AN IMPORTANT CONTRIBUTOR TO . £x°În  2!$!2 (!.$"//+  SEA CLUTTER FOR LOW GRAZING ANGLES AND SHORT PULSES IN PARTICULAR 4HE MAJOR PROBLEM  OF CHARACTERIZING THESE FEATURES IN A MANNER USEFUL TO QUANTITATIVE PREDICTIONS IS STILL BEING ADDRESSED 0ERHAPS THE EXPRESSION  OF THE SCATTERING PROPE RTIES OF THE SURFACE IN  TERMS OF AN INTRINSIC SURFACE PROPERTY LIKE ITS FINE 
 D.C.,May29,1974. 33.Arenberg. D.L.:Ultrasonic SolidDelayLines,J.Acous.Soc.Am.,vol.20,.pp.1-28,January. 
 l~hile thene\v technique \\-as being worked outand theconfidence of pilots and controllers was being developed, 1,5R,lF planes were lost for 1See, forexample, “Radar (.iReport onScience at\Yar),]’Superintendent of Documents, U.S. Go\.ernment Printing Office, H-ashington, D,(i) .iug, 15,194.5.. SEC. 
 The netenergy given totheelectrons during their first passage through thecavity isnegligible when averaged over awhole cycl~, being balanced between acceleration and deceleration. Onthereturn passage, however, most oftheelectrons gothrough inabunch atthemost favorable phase toaid the oscillation. Half acycle later, when returning electrons would absorb energy inbeing accelerated, very few electrons arepassing through. 
 Curve visimpressed a-cvoltage; v=Ecos (cot–@). Figure 1044a shows the voltage waveform across the pulse network ford-cresonance charging, and Fig. 10.44b forthecondition ofmaximum one-cycle voltage step-up, which occurs atanimpressed a-cfrequency about 0.7times theresonant frequency l/(T a. 
 RECEIVE CHANNEL 42  FOR EACH RADIATOR  4HE ADVANTAGES OF !%3!  ARE FAST ADAPTIVE BEAM SHAPING AND AGILITY  IMPROVED POWER EFFICIENCY  IMPROVED MODE INTERLEAVING  SIMULTANEOUS MULTIPLE WEAPON SUPPORT  AND REDUCED OBSERVABIL 
 Sensors 2019 ,19, 2764 geometry for azimuth sidelobes suppression, as shown in Figure 1b. Figure 1b represents the 2 N+1 MPS acquisitions taken from each pass in Figure 1a;Anis the center position of the acquisition on the nth pass,ϕnis the azimuth squint angle, His the height of the center pass, θis the incidence angle andαis the “ﬂight angle”, which is the angle between the line of the center positions (assumed collinear and equally spaced) and the azimuth coordinate; this is given by α=acos⎭parenleftbigg⎭parenleftbigg→ A1An·→y⎭parenrightbigg /⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle→ A1An⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭parenrightbigg . B=⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle→ AnAn+1⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingleis the distance between two adjacent center positions of the SAR and is referred to as the baseline (assumed to be the same for all adjacent pairs), and Ba,n,B//, n, and B⊥,nare the azimuth, parallel, and orthogonal baselines, respectively, which are the projections of the vector→ AnAN+1along the azimuth, the line of sight, and elevation, with the following forms: ⎧⎪⎪⎪⎨⎪⎪⎪⎩B a,n=(n−N−1)·B·cosα B⊥,n=(n−N−1)·B·sinα·sinθ B//, n=(n−N−1)·B·sinα·cosθ, (1) Pis a point target in the scene, and represents the distance between the SAR center position Anand P: Rn(r)≈⎭radicalBig⎭parenleftBig r+B//, n⎭parenrightBig2+B2 ⊥,n+B2a,n≈⎭radicalBig⎭parenleftBig r+B//, n⎭parenrightBig2+(Ba,n)2+B2 ⊥,n⎭slashBigg⎭parenleftBigg 2⎭radicalBig⎭parenleftBig r+B//, n⎭parenrightBig2+(Ba,n)2⎭parenrightBigg (2) where rrepresents the distance between AN+1and P. 
 These ancillary sources are inevitably of finite spectral  purity, with a phase noise floor that may extend over a wide band of frequencies, albeit  at a very low level. Any powerful interfering signals entering the first mixer stage of  the receiver will combine with the phase noise floor and potentially generate products  in the radar signal bandwidth.123,124 In the case of digital receivers, sampling noise will  have an equivalent effect. Digital Receiver Technology. 
 Ringwalt. D. L.. 
 86. A. R. 
 Let usconsider anintensity- modulated indicator tube, such asthe PPI. Let dbethe diameter of the light spot due tothe beam, and letvbethe speed with which the beam isswept across theface ofthetube. Ifd/v<r,thepulse duration, the intervak ofwhich wespoke earlier arespread apart onthe tube; if d/v >r,thespot overlaps several such intervals, orbetter, several such intervals contribute tothesame spot oflight onthetube. 
 VEHICLE INTERFACE  AND INTEGRATED CORE 
 21, pp. 59-63,  March, 1978.  66. 
 Delaney: Spacecraft Phased Array Configurations, IEEE Trans., vol. AP-17, pp. 522-524, July 1969. 
 7. E. F. 
 2 INTRODUCTION TO RADAR SYSTEMS  The name radar reflects the emphasis placed by the early experimenters on a device to  detect the presence of a target and measure its range. Radar is a contraction of the words radio  detection and ranging. It was first developed as a detection device to warn of the approach of  hostile aircraft and for directing antiaircraft weapons. 
 318–323. 3. Pieralice, F.; Proietti, R.; La Valle, P .; Giorgi, G.; Mazzolena, M.; Taramelli, A.; Nicoletti, L. 
 53, pp. 1257-l2S8, September, 1965.  St. 
 In December 1939 trials with ASV Mk I (installed by 32 MU at St Athan) against a surfaced submarine were undertaken. These trials indicated maximum detection ranges of5 ½ miles at 3000 ft and 3 ½ miles at 200 ft [ 2]. However, the minimum ranges, determined by the sea returns, varied between ½ mile in very calm conditions and up to 4 ½ miles. 
 TIME 
      
 Radar MeteoroL, pp. 26-31, American Meteorological Society, Boston, 1975. 77. 
 .........  9  Angular Resolution  ................................ ................................ 
 10.16 (a) Taper coefficient and pedestal height versus peak side- lobe level, (b) Compressed-pulse width versus peak sidelobe level, (c) SNR loss versus peak sidelobe level.PEAK SIDELOBE LEVEL (decibels) <«) PEAK SIDELOBE LEVEL (decibels) 0)WEIGHTING BY COSINE-SQUARED PLUS PEDESTAL COSINE-SQUAREDPLUS PEDESTALDOLPH-CHEBYSHEV TAYLOR (n=8) COSINE-SQUARED.PLUS PEDESTAL TAYLOR (Pi= 8) PEDESTAL HEIGHT H (percent)TAPER COEFFICIENT F1 PULSE WIDTH TO 3-dB POINTS S/N LOSS (decibels) . TABLE 10.9 Taylor Coefficients Fm* *F0 = 1; F_m = Fm; floating decimal notation: -0.945245(-2) = -0.00945245.-50 -45 -45 -40 -40 -35 -30Design sidelobe ratio, dB 10 10 8 8 '5 4 n 1.36/5 1.31/5 1.31/5 1.25/5 1.25/5 1.19/5 1.13/5Main lobe width, -3dB 0.462719 0.126816(-1) 0.302744(-2) -0.178566(-2) 0.884107(-3) -0.382432(-3) 0.121447(-3) -0.417574(-5) -0.249574(-4)0.426796 -0.682067(-4) 0.420099(-2) -0.179997(-2) 0.569438(-3) 0.380378(-5) -0.224597(-3) 0.246265(-3) -0.153486(-3)0.428251 0.208399(-3) 0.427022(-2) -0.193234(-2) 0.740559(-3) -0.198534(-3) 0.339759(-5)0.387560 -0.954603(-2) 0.470359(-2) -0.135350(-2) 0.332979(-4) 0.357716(-3) -0.290474(-3)0.389116 -0.945245(-2) 0.488172(-2) -0.161019(-2) 0.347037(-3)0.344350 -0.151949(-1) 0.427831(-2) -0.734551(-3)0.292656 -0.157838(-1) 0.218104(-2)F1 F2 F, F4 F5 F6 F7 F, F9 . frequency. 
 D" WIDTH OF THE COM 
 TheDoppler frequency shift.Theexpression forthedoppler frequency shiftgivenpreviously byEq.(3.2)isanapproximation thatisvalidformostradarapplications. Thecorrectexpres­ sionforthefrequency f*fromatargetmovingwitharelativevelocityv,whenthefrequencyf istransmitted isll23.70 r*=r(I+(]Ie) . .(1-pic)(3.9). 
 14.4). It is the basis of the earliest successful FM noise-measuring instru- ments and has been employed in stabilization as well.13 It is the only bridge that removes most of the carrier power to avoid saturation of the mixer crystals. The key to its operation is a balancing element which matches exactly the reflection from the cavity at resonance. 
 Because of foldover it is shown as occupying filters 6 and 7 on prf-l, and  filters 7 and 8 on prf-2. With prf-2, the aircraft velocity is shown competing with the rain  clutter; but with prf-1 it appears in one filter (No. 6) without any rain clutter). 
                   
 V olume •  Typically not a major  driver. •  May be a driver if  field deployment is  required•  Depends, a  driver in some  cases•  Typically a  significant driver •  Could be a major  driver depending  on size of antenna  and platform•  A major driver; launch  costs are very high and  are driven by available  volume and mass for  radar payload. •  Once in space,   antenna deployments  are typically needed,  e.g., unfolding, etc. 
 Goldstein, H.: Frequency Dependence of the Properties of Sea Echo, Phys. Rev., vol. 70, pp. 
 The azimuthal dis - tribution of noise from thunderstorms, industrial sites and other sources is far from  uniformly distributed. Furthermore, even so-called clear channels selected for radar  operations are contaminated with directional noise of natural or industrial origin, albeit  at a much lower level. Conventional FFT-type beamforming makes no allowance for  this, so a lot of noise energy leaks into each computed beam through those of its (regu - larly spaced) sidelobes that are pointing toward strong noise sources. 
             
 Figure 3.4 shows  the loci of constant radial velocity along the surface. In order to normalize the figure, a flat  earth is assumed, and the normalized radial velocity Vn = Vr/Vg is presented as a function of  azimuth angle y  and normalized ground range R/H, where H is the aircraft’s altitude. Instead of a single clutter doppler frequency corresponding to a constant radial  velocity ( VB in Figure 3.3) determined by the antenna pointing angle a 0, the radial  sees a continuum of velocities. 
 driven by an S S White ﬂexible drive from the antenna scanner to show the pointing direction of the antenna mirror. This display enabled the Leigh Light to be pointed at the target before being switched on. 4.4 ASV Mk. 
 a transversal fi1ter it is called a four-pulse canceler.)  The weights for a transversal filter with n delay lines that gives a response sin" nf,, T are the  coefficients of the expansion of (1 ...:.. xY,, which are the bi~omial coefficients with alternating  signs:  Input Deloy  r, ( )1-1 n!  Wi= -l (n-i+l)!(i-1)!'  Deloy  Tz Deloy  T3  Summer  Output Deloy  9-/-1 i = 1, 2, ... , n + 1 (4.10)  Figure 4.11 General form of a trans­ versal ( or nonrecursivc) filter for MTI  signal processing. 
 DISTRIBUTION PLOT SUCH AS SHOWN IN &IGURE   4HE CHOICE OF !'# CHARACTERISTICS ALSO AFFECTS THE AMOUNT OF ANGLE NOISE FOLLOWED  BY A TRACKING ANTENNA 4HE !'# VOLTAGE IS GENERATED FROM THE SUM SIGNAL AND FOL 
 2016 ,52, 230–242. [ CrossRef ] 226. Sensors 2019 ,19, 743 14. 
 Skolriik (4.). McCiraw-  Hill Rook Company. New York. 
 IN THE BLIND ZONES IN BOTH DIMENSIONS  42 C02)4 #K02)4 #!C PK! J! r  ¤ ¦¥³ µ´  r  T  rr   J 40 F R# R6 F 02)J KJ KD OR BLIND OR      ;MOD    JJK J 2 R 02) = ;MOD    =rBLIND OR    WHERE 2C IS MAXIMUM DESIGN CLEAR RANGE C IS THE VELOCITY OF LIGHT     MS S P IS TRANSMITTED PULSE WIDTH   K AND J ARE INDICES EG x # IS AN ODD INTEGER EG   # IS AN EVEN INTEGER EG  CJ IS A SMALL PERTURBATION EG z YIELDING VISIBILITY    6BLIND IS A FUNCTION OF F DESCRIBING ECLIPSING AND STRADDLING 2BLIND IS A FUNCTION OF R DESCRIBING ECLIPSING AND STRADDLING # IS A CONSTANT REPRESENTING THE REMAINDER OF THE RANGE EQUATION F IS FREQUENCY  R IS RANGE  MOD IS MODULO THE FIRST VARIABLE BY THE SECOND 2ANGE 
 -AGNITUDE D" -AXIMUM      &)'52%   /35 
 Author Contributions: Conceptualization, W.C. and H.T.; Formal analysis, W.C., H.T. and G.S.; Methodology, W.C. 
 FICIENTS AUTOMATICALLY PROVIDE A LINEAR PHASE SHIFT OVER FREQUENCY  INTRODUCING LITTLE OR NO PHASE DISTORTION TO THE FILTERED SIGNAL  WHICH IS HIGHLY DESIRABLE IN MANY APPLICA 
 This is the key reason we suppose as the cause of the subsidence recovery that occurred from August 2015. 243. Sensors 2019 ,19, 3073 5.3. 
 Ê " *, 
 Wingham, l. Phalippou, C. Mavrocordatos, and D. 
 Theunsteady motions oftheplatform cancauseerrorsintheangularmeasurement and distortion ofthedataonindicators likethePPI.Corrections canbeappliedinsomecasesto account forthesedistortions. Thisiscalleddatastabilization. Correction ofthedatamaystill. 
 514. This shows, in thefull curve; asinusoidal depend- ence ofthe transmitted frequency on time. The total frequency swing ismade large compared to the doppler frequency. 
 The transmitted waveform can be pulse,  CW, FM-CW, FM (chirp) pulse, or other pulse-compression coded waveforms. Pulse com­ pression is used for the same reason as in microwave radars. Spectral bandwidths of from  approximately 5 kHz to 100 kHz might be used, corresponding to effective pulse widths of  200 JLS and 1011s, respectively. 
 Plate II (p. 112). Type A Range Display. 
 In some applications, the effect of multiple, independent beams can be obtained with a  single-beam phased-array radar which is capable of flexible and rapid beam steering. For  example, a sequential burst of pulses can be transmitted at the beginning of the transmission,  with each pulse radiated in a different direction. This requires rapidly switching phase shifters  to steer the beam between pulses. 
 4.18.22 The dashed curve is the response of a five-pulse canceler  with fixed prf and with weightings of i, 1, - 32, 1,;. The solid curve is for a staggered prf with  ---- Fixed prf  Staggered prf  Target veiocity relative to first blind velocity at fixed prf  Figure 4.18 Response of a weighted five-pulse canceler. Dashed curve, constant prf; solid curve, staggered  prf's. 
 GATE TRACKING   BOTH COARSE THE ALPHA LOOP  AND FINE RANGE 
 Research Station. It soon became evident that airborne radars would be needed and a team was set up to research this problem, under the leadership of E G Bowen. This was a completely new ﬁeld of research which required a very different approach to that used for the ground-based radars. 
 Skolnik: A Bistatic CW Radar, MITLincoln Laboratory Tech. Rept. 82, AD 76454, Lexington, Mass., June 6, 1955. 
 The bistatic receiver is sometimes said to hitchhike off a cooperative or noncooperative transmitter, usually a monostatic radar. Table 25.1 summarizes useful bistatic radar applications permitted by operat- ing regions and transmitter configurations. The two omitted entries on the "Transmitter-centered" row are operational constraints: a dedicated or coopera- tive transmitter can usually gather nearby data in a monostatic radar mode more easily than can a remote, bistatic receiver. 
 With FM mod u- lation the FM pass is added.  For the tr ansmitting/receiving duplexer 6x λ/4 hybrids are used.   These lead a priori to a loss of over 6 dB. 
 This can result in an error in measurement even if no noise is  present. It is possible to alleviate this situation, however, by using an adaptive threshold in  which the level of the threshold is always a fixed fraition of the pulse amplit~de.~  Range accuracy using gating signals and matched  filter^.^ Consider the receiver block diagram  shown in Fig. 11.2 consisting of a multiplier followed by a low-pass filter (or integrator). 
 contained in the two-way path between the radar and the target  is 2R/ X The distance R and the wavelength ). are assumed to be measured in the same units.  Since one wavelength corresponds to an angular excursion of 2n radians, the total angular  excursion ct, made by the electromagnetic wave during its transit to and from the target is  411:R/,i radians. 
 TYPE JAMMERS WHEN USING A SUITABLY POSITIONED HITCHHIKER NECESSITATES DISTINGUISHING COOPERATIVE FROM NONCOOP 
 F. Ramsay, “Lambda functions describe antenna diffraction pattern,” Microwaves , pp. 70–107,  June 1967. 
 5X9 582, 1131:l'. Cat. no. 
 Parallel-plate feeds.Afoldedpillboxantenna(Fig.8.24),aparallel-plate horn,orothersimi­ larmicrowave devicecanbeusedtoprovidethepowerdistribution totheantennaelements. Thesearereac(il'efeedsystems. Theyarebasically usedwithalineararrayandwouldhaveto bestackedtofeedaplanararray. 
 Unfortunately, this process folds the spectrum so that incoming targets are indistinguishable from outgoing targets and the random-noise sidebands accompanying each appear in the baseband amplifier. Even if one is prepared to accept the ambiguity, the 3 dB loss in the signal-to-noise ratio (SNR) is a matter of concern in a high-power radar. There are two alternatives, both of which have been extensively employed. 
 CLUTTER RATIO WHERE THE TARGET IS  FOR EXAMPLE  A MANMADE OBJECT 3WARTZ ET AL  FOUND A POLARIZATION THAT GAVE A  D" TARGET 
 An intensity modulated display with height (altitude) as the vertical axis  and range as the horizontal axis.  The above definitions are taken from the IEEE Standard  definition^,^^ with some  modifications. The terms A-scope and A-display, B-scope and B-display, etc., are used inter-  changeably. 
 The use of a radar with liigli rangc-  ' corresponding zero L, angle error voltage range video  ongle video  ____j.  time  Figure 5.20 Rangc and angle video obtained with the NRL High Range Resolution Monopulse (HRRM)  radar The target is a Super Constellation aircraft in flight. Note that the angle video indicates to what side  of the radar beam axis are located the individual scatterers which are resolved in range. 
 SEARCH RADAR AND SMALL MISSILE TARGET PROBABILITY OF DETECTION. 
 but generally is of little interest in radar since extremely  low noise receivers are not always desirable.  Still another advantage of the Cassegrain antenna is the flexibility with which different  transmitters and receivers can be substituted because of-the avai\abi\ity of the antenna feed  system at the back of the reflector rather than out front at the normal focus. The Haystack  microwave research system,24 for example, is a fully steerable Cassegrain antenna 120 ft in  diameter. 
 Frequency considerations. TheARSR-3 described aboveoperates atLband(1250to 1350MHz).Thisisagoodcompromisc frequency foralong-range air-surveillance radar. Higherfrequencies canprovide thesameangular beamwidths withsmallerantennas, butthe smallerapertures mustbecompensated bygreaterpowerifthemaximum rangesarethesame. 
 RANGE REGION DISAPPEARS BECAUSE THE  SIDELOBE CLUTTER FOLDS IN RANGE INTO THE UNAMBIGUOUS RANGE INTERVAL ASSUMING THE TAR 
 CONTROLLED VACUUM TUBES HAVE BEEN SUCCESSFULLY USED UP TO ABOUT  -(Z 4HE BARRIER OF TRANSIT TIME EFFECTS WAS OVERCOME WITH THE INVENTION OF THE MICRO 
 Water (ship) W. Automatic flight or remote  control T. Transportable (ground) X. 
 Figure 12.36 shows a snapshot of the Workbench GUI window,  including a rendering of an offset-fed reflector and its associated beam pattern. More  information is available at esl.eng.ohio-state.edu. 12.6 MECHANICAL DESIGN CONSIDERATIONS Reflector mechanical design is a detailed discipline unto itself with a multitude of  factors to consider. 
 HALF THE SPEED OF MAXIMUM RESPONSE "ECAUSE IT IS DESIRABLE TO AVERAGE THE TRANSMITTER DUTY CYCLE OVER AS SHORT A PERIOD AS POSSIBLE  THE  PULSE 
 L. Barasch, and T. A. 
 TO 
 SEC. 6,5] REPRESENTATION OF THE HORIZONTAL PLANE 169 Inspite ofthe usefulness ofatrue map display such asthe PPI, occasions arise inwhich itisnotideal. These situations usually involve the need forproviding high resolution ordispersion insome particular coordinate without restricting the field ofview too severely inother dimensions. 
 (12.9)] is to decrease with heigllt, 1111: temperature must i~~crcasr:  and/or the humidity (water-vapor content) must decrease with heigllt. An increase of tempera-  ture w~th height is called a trmprratlrre ir~urrsion and occurs when the temperature of tlie sea or  land surface is appreciably less than that of the air. A temperature inversion, by itself, must be  very pronounced in order to produce superrefraction. 
 Airborne Radars.  Whereas commercial aviation weather radars are nose  mounted X-band radars for severe weather and turbulence detection and avoidance,  airborne research radars must have relatively more complex architectures169 in order to  make more sensitive, high-resolution measurements. This powerful technique permits  the use of a mobile platform, which therefore allows measurements over regions not  accessible by ground-based systems. 
 At this time, the matched function of consistent compression is: HCOMP (kr,kx)=jR S/radicalBig k2r−k2x+jkxRstanθ (14) where, Rsis the closest distance from the center point of the scenario to the aircraft trajectory. After consistent compression, the point at the center of the scenario is completely focused, and the residual phase at the other range is: θRFM(kr,kx)=−(Rb−RS)/radicalBig k2r−k2x−kx(Xi−Rstanθ) (15) The RMA algorithm performs range cell migration compensation, secondary range compression and azimuth compression by interpolation ky=/radicalbig k2r−k2x[1,17]. For 20◦squint, the two-dimensional spectrum is distorted, and it needs to extract a rectangular aperture of data adequately in such 2-D support [ 18], as shown in Figure 5; it needs to discard part of the spectrum due to the squint angle, which reduces the energy of targets after imaging. 
 f,. = Jo T = -Jo  C (3.10)  In any practical CW radar, the frequency cannot be continually changed iri one direction  only. Periodicity in the modulation is necessary, as in the triangular frequency-modulation  waveform shown in Fig. 
 Obviously, whentherauaris lIseuinitstracking moue,ithasnoknowleugeofother potential targets.Also,iftheantenna pattem isanarrowpencilbeamanuifthesearchvolumeislarge,arelatively longtimemight hercquireu tofinuthetarget.Therefore manyradartracking systems employaseparate search radartoprovide theinformation necessary toposition thetrackeronthetarget.Asearch radar.whenusedforthispurpose. itcalleuanacqllistioll radar.Theacquisition radardesig­ lIatestargetstothetracking radarbyproviding thecoordinates wherethetargetsaretobe found.Thetracking radaracquires atargetbyperforming alimitedsearchintheareaofthe designated targetcoordinates. Thescanning fan-beam searchradarcanalsoprovidetracking information todetermine thepathofthetargetandpredictitsfutureposition. 
 The high-dimensional target signal can be accurately reconstructed by applying low-dimensional observation data by solving a minimum L-norm constrained optimization problem. At present, many scholars are combining CS with high-resolution near-ﬁeld imaging and have achieved a number of research results, which fully demonstrate great potential of CS in reducing data sampling rate and improving imaging resolution [ 3,8,22,23]. At present, research on near-ﬁeld 3-D imaging mainly focuses on planar scanning 3-D imaging. 
 P. Rowe, watching on  behalf of the Air Ministry, was able to report that “‘in  the circumstances the result was much beyond expecta-  tion.” What -he had actually been able to see on the  cathode-ray tube inside the lorry was the tiny ‘blip’ (a deflection of the time-base line at one point) caused __ by refiection of the Daventry signals from Heyford  _ ‘aircraft fying in a certain direction, within eight miles,  | ‘Brom thas tiny beginning grew radar. :  . 
 W. T. Davis. 
 507, October 1975. 26. Peterson, W. 
 Furthermore, the problem is complicated at the vertical by the fact that  the angular scale terminates there, so that a beam centered at the vertical illuminates  weaker targets ( s 0) on both sides of its pattern, whereas a beam away from the vertical  illuminates stronger signals on one side and weaker signals on the other . Figure 16.18 shows what happens for a steeply descending curve of s 0 versus q.  The radar return integral from Eq. 
  SPACECRAFT OF %3! DENOTES THE SCATTEROMETER MODE  EMBEDDED IN THEIR # BAND !-) RADAR INSTRUMENTATION 4HESE SCATTEROMETERS USED THREE  FAN 
 Janza, R. K. Moore, and B. 
 Consequently, the analysis has the following tasks:   To correctly filter the amplitude and phase o f the reception spectrum,   To apply a Fourier transform to the linear FM.   10.7 PRF Determination   The resolution D of SAR in azimuth is, as has been shown, equal to half of the antenna length  a/2.  For processing a pulse must be available for each resolution cell  of the azimuth, since  otherwise the optimal resolution cannot be achieved. 
  
 CENTERED SWATH   KM WIDE &IGURE   4HE FIRST 3EA7INDS MISSION WAS ABOARD 1UIK3#!4  MOBILIZED BY .!3! AND LAUNCHED IN *UNE  AS A RAPID RESPONSE TO THE PREMATURE LOSS OF !$%/3 IN *UNE  4HE SECOND 3EA7INDS WAS EMBARKED ON *APANS !$%/3 
 6), con-  _ Sisting of a condenser C and a resistance R. This looks  . ‘IMPOSSIBLE’ CIRCUITS 87  simple enough, even to the hidebound radio man, but  in radar this is a ‘differentiating’ circuit if the values are  correctly chosen; so let us see what happens. 
 BAND RADIO WAVES  0ART )) 
 The mount in (!)  might be desired where antenna elevation is not required. The arrangement in (g) can be  trained on target with minimum rate or acceleration requirements on all axes, irrespective of  the position of the target or motion of the platform. In the three-axis arrangement or (h) a  stable base is provided in which a roll axis lies in a fixed position parallel to the fore.and-aft  line of the vehicle. 
 The altitude  of the tradewind duct varies from hundreds of meters at the eastern part of the tropical oceans  to thousands of meters at the western end. Thus, the height gradually rises in going from east  to west. There is also a general decrease of the refractivity gradients to the west. 
 The author and . his colleagues at the University of Michigan undertook development of the fo- cusing concept suggested by Dr. Sherwin. 
 OF 
 51–83, January 1978. 36. E. 
 Random electronic scanning effectively prevents these deception jammers from  synchronizing to the antenna scan rate, thus defeating this type of jammer. A high- gain antenna can be employed to spotlight a target and burn through the jammers. An  antenna having multiple beams can also be used to allow deletion of the beam con - taining the jammer and still maintain detection capabilities with the remaining beams. 
 If the boresight *A sine or a millisine is a unit of measure of the sine of an angle. For example, an angle of 0.7 rad (700 mrad) corresponds to sin (0.7) 0.64422 sine = 644.22 msines. NORMALIZED SENSITIVITY FACTOR K' = K-X/L = 1/RMSE V^ . 
 ,, 
  AND  LATE 
 This course is different from those usually found in most graduate electrical  engineering programs. Typical EE courses cover topics related to circuits, components, de-  vices, and techniques that might make up an electrical or electronic system; but seldom is the  student exposed to the system itself. It is the system application (whether radar, communica-  tions, navigation, control, information processing, or energy) that is the raison d'itre for the  electrical engineer. 
 PRISED OF A SCATTEROMETER AND A WINDWAVE MINI 
 4.2c. hut not when the measurement is made on the basis of a sing!e pulse. The video  signals shown in Fig. 
 H. Prager, and J. L. 
         
 E. F. Knott, J. 
 Kelly: Low-Noise Receiver Design Trends Using State-of-the-Art Building  Blocks, l EEE Trans., vol. MTI-25, pp. 254-267, April, 1977. 
 The Pl9 is a single-component phosphor  with long persistence and no flash. If extremely long persistence is desired in a cathode-ray-tube  display, a storage tube may be used. For all practical purposes, an image placed on a storage  tube will remain indefinitely until erased. 
 (14.22) since it  is sometimes convenient ii1 0TH radar to have separate antennas for these two functions. If  narrow beamwidths are to be achieved, the radar antenna must be a physically large phased  array. A one-degree beamwidth, for example, requires an aperture of about 1200 m at a  frequency of 15 MHz. 
 WIDTH GUIDE WHERE THE TWO MODES ADD IN THE CENTER AND SUBTRACT AT THE OUTER HUMPS OF THE 4%  MODE 4HE RESULT IS A SUM 
 Skolnik (ed.), McGraw-Hill Book Co., Inc., New York, 1970.  2. Barton. 
 Am. Meteorol. Soc. 
 RECEIVER PATH  CALLED THE DIRECT 
                     &)'52%  #OLLAPSING LOSS VERSUS COLLAPSING RATIO FOR A PROBABILITY OF FALSE ALARM OF  
 +1, 
 TO 
 IRE , vol. 50, pp. 456–461, 1962. 
 OBSERVED FINE LINES  IN THE OPTICALLY CLEAR BOUNDARY LAYER  REFLECTIVITY CONTRIBUTIONS FROM AERIAL PLANKTON AND ITS PREDATORS v  "OUNDARY ,AYER -ETEOROL     VOL   PP n    0 ( (ILDEBRAND   h)TERATIVE CORRECTION FOR ATTENUATION OF  CM RADAR IN RAIN  v * !PPL -ETEOROL    VOL   PP n    2 ( !LLEN  $ 7 "URGESS  AND 2 * $ONALDSON  *R  h3EVERE  
 Itisimportant tounderstand theoriginsoftheselosses,notonlyforbetter predictions ofradarrange,butalsoforthepurposeofkeeping themtoaminimum bycarefuJ radardesign.. 2.13 PROPAGATION EFFECTS  In analyzing radar performance it is convenient to assume that the radar and target are 110th  located in free space. However, there are very few radar applications which approximate  free-space conditions. 
 In addition, most operational radars do not use ultralow (less than  −40 dB) or low ( −30 to −40 dB) sidelobe antennas and have antenna sidelobes in the  −20 to −30 dB region with average sidelobes of 0 to 5 dB below isotropic. SLC has  the potential of reducing noise jamming through the antenna sidelobes, and it is used  for this purpose in operational radars.3 As explained in Section 24.9, ECCM techniques against chaff are mainly those  based on coherent doppler processing.3,152 In particular, the reference152 describes a  comparison of fixed and adaptive doppler cancelers applied to chaff data recorded by  a multifunctional phased-array radar operating at S band. Both cancelers process an  8 pulse coherent burst. 
   )NTERNATIONAL %LECTROTECHNICAL #OMMISSION  'ENEVA    '-$33 (ANDBOOK  ND %D  ,ONDON )NTERNATIONAL -ARITIME /RGANIZATION    h4ECHNICAL PARAMETERS FOR RADAR TARGET ENHANCERSv )45 2ECOMMENDATION -  )NTERNATIONAL  4ELECOMMUNICATION 5NION  'ENEVA  4 0 ,EONARD AND 3  * "RAIN  h2ADAR PERFORMANCE TEST -ETH ODSFINAL REPORT v 2ESEARCH 0ROJECT  20  5+ -ARITIME AND #OASTGUARD !GENCY  3OUTHAMPTON    h2ECOMMENDATION  6 
 The filter has to be retuned if the mixer must operate at another  frequency. Also, the high Q of the filter introduces a loss which will increase the system  noise-figure.  A method for achieving a reactive termination without narrow-bandwidth components is  the image-recovery mixer shown in Fig. 
 GER 02& SYSTEMS MUST BE CHOSEN PRIMARILY ON THE BASIS OF MAINTAINING THE STOPBAND RATHER THAN FLATTENING THE PASSBAND 3IMILARLY  HIGHER 
 4, pp. 29–49, July 1996. 83. 
 The basic pulse triggers aflip-flop having alifetime slightly greater than the maximum delay ofthe sine pulse; theresulting square wave isused toswitch asawtooth generator of very low output impedance. Thus, within the lifeofthe sawtooth, the instantaneous voltage atSisproportional totime elapsed since the occurrence ofthebasic pulse. When thesine pulse occurs, itmomentar- ilycloses the “double clamp” (similar toFig. 
 ~.,," r+Todata processi/i., ordisplay Range gate No.nBoxcar generatorThreshOld Figure4.19Blockdiagram ofMTIradarusingrangegatesandfilters. Following thedoppler filterisafull-wave lineardetector andanintegrator (alow-pass filter).Thepurpose ofthedetector istoconvert thebipolarvideotounipolar video.The outputoftheintegrator isappliedtoathreshold-detection circuit.Onlythosesignalswhich crossthethreshold arereported astargets.Following thethreshold detector, theoutputsfrom eachoftherangechannels mustbeproperly combined fordisplayonthePPIorA-scopeorfor anyotherappropriate indicating ordata-processing device.TheCRTdisplayfromthistypeof MTIradarappears" cleaner" thanthedisplayfromanormalMTIradar,notonlybecauseof betterclutterrejection, butalsobecausethethreshold deviceeliminates manyoftheunwanted falsealarmsduetonoise.Thefrequency-response characteristic oftherange-gated MTlmight appearasinFig.4.20.Theshapeoftherejection bandisdetermined primarily bytheshape ofthebandpass filterofFig.4.19.' Thebandpass filtercan'bedesigned withavariable low-frequency cutoffthatcanbe selected toconform totheprevailing clutterconditions. Theselection ofthelowercutoffmight beattheoptionoftheoperator oritcanbedoneadaptively. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section.  RADAR CROSS SECTION  14.396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 Two approaches may be taken in the application of shaping. 
 ENTRY %ACH OF THESE PHASES OF FLIGHT HAS A DISTINCT TARGET MODEL  $URING BOOST  THE TARGET IS CONTINUALLY  ACCELERATING AND INCREASING SPEED 4HIS ACCELERATION IS UNKNOWN AND MUST BE ESTIMATED $URING EXO 
 4(% 
 34TARGET CHARACTERISTICS There are several target characteristics which will enable one target to be detected at a greater range than another, or for one target to produce astronger echo than another target of similar size. Height Since radar wave propagation is almost line of sight, the height of the target is of prime importance. If the target does not rise above the radarhorizon, the radar beam cannot be reﬂected from the target. 
 Thestandard rx-f1trackerdocsnothandlethemaneuvering target.However, anadaptive 'Y.-f1trackerisonewhichvariesthetwosmoothing parameters toachieveavariable bandwidth soastofollowmancuvers. Thcvalueofexcanbesetbyobserving themeasurement error .'("-.'(,,".Atthestartoftracking thebandwidth ismadewideandthenitnarrowsdownifthe targetmovesinastraight-line trajectory. Asthetargetmaneuvers orturns,thebandwidth is widened tokeepthetracking errorsmall. 
 MULATOR  THE SPURIOUS FREQUENCY SPACING  CAN BE AS CLOSE AS  (Z )N MOST CASES  SUCH  CLOSELY SPACED SPURIOUS SIGNALS CANNOT  BE DIFFERENTIATED FROM NOISE #ONVERSELY  CHOOS 
 BAND INTERFERENCES RESULTING IN POOR CLUTTER CANCEL 
 Februar).. 1957.  3. 
 20.5 WAVEFORMS FOR HF RADAR The factors that govern the choice of waveform in HF radar systems can be grouped  into two classes. First, there are the considerations common to microwave radar, that  is, range and doppler resolution as described by the ambiguity function and optimized  ch20.indd   21 12/20/07   1:15:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 BASED !IRBORNE 3PACEBORNE 3TOWAGE $EPLOYMENTs  #AN BE A DRIVER  IF SYSTEM IS TRANSPORTABLEs  4YPICALLY NOT A  REQUIREMENTs  4YPICALLY NOT  A REQUIREMENT  BUT THERE ARE EXCEPTIONSs  4YPICALLY REQUIRED   GENERALLY A MAJOR DESIGN DRIVER s  2ELIABILITY OF  DEPLOYMENT IS A MAJOR CONCERN MISSION DEPENDS ON IT /THER s  )S TRANSPORTABILITY  A REQUIREMENT  !RE THERE MULTIPLE ENVIRONMENTS TO WHICH THE RADAR ANTENNA WILL BE EXPOSED s  7HERE ON THE  SHIP IS THE RADAR ANTENNA  )S IT COVERED WITH A RADOME  7ILL IT BE EXPOSED TO WATER OR WAVE SLAP s  6OLUME IS A MAJOR  CONSTRAINT  NOT MUCH ROOM FOR ANTENNA APERTURESs  3PECIALIZED  ENVIRONMENTS     s  ,AUNCH DRIVES  VIBRATION AND ACOUSTIC LOADS     s  2ADIATION A DRIVER AT  SOME ORBITS     s  4HERMAL EXTREMES   INCLUDING GRADIENTS  ARE A CONCERN4!",%  -ECHANICAL $ESIGN $RIVERS FOR 2EFLECTOR !NTENNA 3YSTEMS AS A &UNCTION OF 0LATFORM  #ONTINUED  . 
 It can be programmed to remain  silent whe,{ illuminated by the main radar beam and to transmit only when illumihated by the  sidelohes. creating spurious targets on the radar display at directions other than that of the  true target.  A rcmyc-yate .Healcr is a repeater jammer whose function is to cause a tracking radar to  ·· break lock" on the target. 
 In  the design of the receiver, A/D converter, and digital processing it is also important to perform the major portion of the s pectral weighting in the receiver filters, since this will result in the  lowest possible A/D converter -sampling rate. In the signal processor the phase portion of the  "Matched Filter" operation is performed using either the fast Fourier transform (FFT) or a fi- nite i mpulse response (FIR) filter.  Each of these design processes will be discussed and illustrated by examples. 
 49.Cohn.M..andA.F.Eikenberg: Ferroelectric PhaseShifters forVHFandUHF,IRETral/s. \01.MTT-IO, pp.536-548. November, 1962. 
 MTI RADAR  2.496x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 Figure 2.50 shows the residue if the transmitter starts radiating as the peak of the  beam passes the point clutter. Forty-nine pulses after the transmitter starts radiating,  the residue has decayed only 27 dB. It would take at least another 50 pulses for the  residue to decay to −60 dB. 
 Rummler, W. D.: Introduction of a New Estimator for Velocity Spectral Parameters, Tech. Memo. 
 3, 1946.. 656 MOVING-TARGET INDICATION [SEC. 16.12 depression angles; some other method must beused, such asthenonco- herent method now tobedescribed. 
 , 
 !  0 % #ORNWELL AND * ,ANCASTER  h,OW 
 Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters.  SOLID-STATE TRANSMITTERS  11.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 will not “fail” in less than three months; however, the cost of replacement modules and  labor would be very unattractive because nearly 40% of the transmitter would have to  be replaced every year. Higher MTBFs are thus essential to ensure that the transmitter  is not only available but also affordable. 
 By putting aside the power doubling achieved with two transmitters at constant frequ encies, the  maximum range through frequency diversity mode can never be better due losses caused by  fluctuation  (3 to 8 dB) . Radartutorial (www.radartutorial.eu)   18 Training Questions     Please try to answer some of the more frequently asked training questions.   The reasonable time to frame the a nswers is about 30 minutes. 
 T. Swift, “The Seasat microwave instruments in historical perspective,”  IEEE Journal of Oceanic Engineering , vol. OE-5, pp. 
 In addition the MTI . Radar System Engineeri ng Chapter 8 – Pulse Radar  56     function can be obtained on the IF side.  The equations from above apply with the substitution  ωd → ω ZF ± ωd. 
 When this occurs, tile  narrow sector in the direction of the jammer will appear as a radial strobe on the )?PI display.  The directbn to the jammer can be determined, but its range and the ranges of any targets  masked by the noise strobe is not likely to be known. If noise enters the radar via the antznna  sidelobes, the entire display can be obliterated and no target information obtained. 
 Compared with computer vision, SAR image interpretation has the same purpose—extracting useful information from images—but the processed SAR image is signiﬁcantly different from visible light image, mainly reﬂected in the band, imaging principle, projection direction, angle of view, etc. Furthermore, the small dataset may be a problem, too. Therefore, when we use the method in SAR images, we need to fully consider these problems. 
 R is typically taken to be the range from the radar to the target. The symbol a has been widely accepted as the designation for the RCS of an object, although this was not so at first.1'2 The RCS is the projected area of a metal sphere which is large compared with the wavelength and which, if substi- tuted for the object, would scatter identically the same power back to the radar. The RCS of all but the simplest scatterers fluctuates greatly with the orientation of the object. 
 Advances in  gyrotrons (Chapter 10) can produce average power many orders of magnitude greater  than more conventional millimeter-wave power sources. Thus, availability of high  power is not a limitation as it once was. Laser Radar. 
 141-148.  36. Welti, G. 
 Olsen: Nonparametric Radar Extraction Using a Generalized Sign Test,  IEEE Trans., vol. AES-7, pp. 942-950, September, 1971. 
 However. the  beamwidth rather than the antenna gain is usually measured at laser frequencies so that  (i, = rr2 ;oi may he substituted into the radar equation. The minimum detectable signal for  quantum-limited detection is85  s . 
 197-203, IEEE Publ. 80 Ch 1578-4 AES, Sept. 29, 30, Oct. 
 Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar.  GROUND PENETRATING RADAR  21.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 in which high frequencies are radiated first, followed by the low frequencies. A “spik - ing” filter, which may take the form of a conventional matched filter, however, may  compensate for this effect, or a more sophisticated filter such as Wiener filter, which  recovers the original shape of the waveform, applied to the antenna. 
 I5 I. Gabriel, W. F. 
 (/?) Squinted-sum-beam low-angle technique. technique examined consists of a uniformly illuminated transmit/receive lower beam, accompanied by a weighted aperture upper beam. The lower beam is elec- tronically phase-steered to U1= 0.5 while the upper beam is electronically phase- steered an additional o// = 1.0 (i.e., to W2 = 1.5). 
 CW ra- dars have been made to work by using separate transmit and receive antennas to isolate the receiver from the transmitter. When the two antennas cannot be widely enough separated to reduce transmitter leakage into the receiver below the receiver noise level (such as when both antennas have to be on the same ve- hicle), the residual transmitter leakage can be reduced by feedthrough nulling, which works by using negative feedback at the receiver input to cancel whatever transmitter carrier signal may appear there. The feedback loop must be selective . 
 580 INDEX  Speckle, in SAR, 528  Speed gate, 81  Sphere, radar cross section of, 33-34  Spherical reflectors, 245-246  Spike leakage, and diode burnout, 350  Spikes, and sea clutter, 477  Spin-tuned magnetron, 199  Spiral scan, 178  Split range gate, 176-177  Spotlight mode, SAR, 527  Spread spectrum, 434  Squint angle, 155, 158-159  Squint mode, SAR, 527  Stabilization of antennas, 270-273  Stacked-beam 30 radar, 543-544  Staggered prf, in MTI, 114-117  Stalo, 105  Standard deviation, 21  Standard temperature, 19  STC:  in ARSR-3, 540  and duplexer, 366  and logarithmic receiver, 507  and sea clutter, 488  and shaped beams, 261  Storage tube, 357-358  MTI, 126  Straddling loss, 61  Straps, magnetron, 193  Stretch pulse compression, 432  Structure constant, 511  Subarrays, 309-310  Subclutter visibility, 129-130  Submillimeter wavelengths, 564  Surface acoustic wave delay lines, 424-426  Surface duct, 451, 453-455  Surface, for reflector antennas, 239-240  Surveillance radar range equation, 64  Swerling cross section models, 46-49  Switched-line phase shifter, 288  Synthesis of antenna patterns, 254-2S8  Synthetic aperture radar, 517-529  Synthetic video displays, 359  System losses, 56-61  System noise figure, 346  System noise temperature, 345, 463-465  Systematic errors:  antenna, 262  tracking, 180  TACCAR, 142  Tapped-delay-line integrator, 390  Target classification, 434-438  Taylor aperture illumination, 257-258 Tellurometer, 97  Thermal noise, 18  Thin,wall radome, 267  Thinned arrays, 309, 319, 331-332  Three-axis mount, 271  30 radar, 301, 541, 544  Three-pulse canceler, 109-110  Threshold detection, 16-17, 27  Thumbtack ambiguity diagram, 418-419  Time-difference height finding, 546-547  Time-frequency coded waveform, 431  Tolerances, in lenses, 253-254  Torque fins, antenna, 269  TR tube, 361-362 )  Track initiation and maintenance, 325-326  Track-while-scan radar, 152-153, 183  sector scanning, 248  Tracking, automatic, 153, 183-186, 392  Tracking illuminator, CW, 73, 81  Tracking radar, 152-186  angular accuracy, 167-172  conical scan, 155-159, 182-183  conopulse, 164  glint, 168-172  Jobe switching, 153  low-angle, 172-176  monopulse, 160-167, 181-183, 435  off-axis tracking, 174  on-axis tracking, 180-181  scan with compensation, 164  sequential lobing, 153-154  simultaneous lobing, 160  ' Tracking with surveillance radar, 183-186  Transient response, in MTI, 113-114  Transistors:  low noise, 351, 352  power, 217  Transmitter noise, 73-74  Transmitter power, 52-53  Transmitters, 190-220  Amplitron, 209  crossed-field amplifiers, 208-213  grid-controlled tubes, 213  klystron, 200-205  magnetron, 192-200  modulators, 214-216  solid-state, 216-220  traveling-wave tube, 206-208  Twystron, 208  Transreftector, 242  Transversal filter, 110-114  Traveling-wave tube phase shifter, 297  Traveling-wave tubes, 206-208  Triangular element spacing, 333-334 . True-hearing display, 271  True time delays, in arrays, 288  Tuning:  klystron, 203  magnetron, 199 ·· 200  Twin-slab toroidal phase shifter, 294  Twist reOector. 242 243  Two-frequency CW, 95 97  Two-frequency MTI, 147 148  Twystron, 208  Type 11 servo system. 
 They internally generate or amplify electromagnetic energy, which is then radiated. Passive  electronic countermeasures do not generate or amplify electromagnetic radiation. They act in  a passive manner to change the energy reflected back to the radar. 
 SANDWICH  C  " 
 Kretschmer, F. F.: MTI Weightings, IEEE Trans., vol. AES-10, pp. 
 The decor-  relation times at 95 GHz varied from about 3.4 ms at 5 mm/h rain rate to 1.4 ms at 100 mm/h.  At X band the decorrelation times were longer and varied from 14 ms at 5 mm/h to 5.4 ms at  100 mm/h.  Utility of millimeter waves. 
 Range gating excludes undesired targets and noise. The system also includes an automatic gain control (AGC) necessary to maintain constant angle sensitivity (volts of error-detector output per degree of . FIG. 
 The strongest requirement forawell-matched line arises from the properties ofthe magnetron. Like allself-excited oscillators, the mag- netron exhibits anoutput frequency and astability dependent upon the load into which itworks. Amismatched line represents aresistance lower than 20atvoltage minimum, and higher than ZOatvoltage maxi- mum. 
 3. To get a long unambiguous range, An1 should be large. 4. 
 This incidence variation helped to offset the large change in radar range  to the imaged swath, but it meant also that the range resolution as expressed on the  surface varied as a function of latitude. For a constant radar bandwidth, the effec - tive surface range resolution at shallower incidence is improved over that achieved at  steeper incidence. Fortunately, at steeper incidence, and hence at longer ranges, there  was more time available to gather more looks. 
 83-88, January 1970. 97. Ewell, G. 
 The bipolar junction transistor (BJT) is so named because the conduction path  through the transistor makes use of both majority and minority charge carriers to estab - lish current flow in the semiconductor. It is a current-controlled device with the collec - tor current modulated by the current flowing between the base-emitter junction. This  compares to the operation of a field effect transistor (FET), or a unipolar device, where  charge is carried with only one type of charge carrier. 
 As discussed in chapter 7ASV Mk. III also produced better detection ranges than ASV Mk. II. 
 His work preceded the orginal electro­ magnetic echo experiments of Hertz by about fifteen years. The Rayleigh scattering region is of . 34 INTRODUCTION TO RADAR SYSTEMS  N  t:l  I=::  '-.. 
 RANGE SURVEILLANCE IN THE RECEIVER 
 TIONS  IT IS COST 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°{x A TRACK FROM THREE OUT OF FIVE  TO FIVE OUT OF EIGHT  INCREASES THE DENSITY OF FALSE  ALARMS THAT CAN BE TOLERATED BY MORE THAN AN ORDER OF MAGNITUDE &ORWARD 
 Performing the Fourier analysis to these two data sets shown in Figure 3a,b, respectively. 73. Sensors 2019 ,19, 1920   (a) ( b)  7LPH V 1RUPDOL]HG$PSOLWXGH  7LPH V 1RUPDOL]HG$PSOLWXGH)RUZDUG %DFNZDUG   (c) ( d)  1RUPDOL]HG$PSOLWXGH )UHTXHQF\ +]   1RUPDOL]HG$PSOLWXGH )UHTXHQF\ +]  Figure 3. 
 ERROR SENSING SIMILAR TO THE COMPARISON OF AMPLITUDES IN THE EARLY 
 C I.: Coherent and Incoherent Scattering of Microwaves from the Ocean, I RE Trans.,  vol. t\P-9, pp. 470-483, Sept., 1961. 
 POLARIZATION AND THE  TWO 
 3, pp. 234–242, June 2006. 174. 
 In  Fig. 8.29 one beam sampling channel is illustrated. The sampling signal Sa is a train of short  pulses at a repetition ratefs which can be time-phased to gate the scanning signal 6r according  to the desired beam direction. 
 For aflat metal sheet ofarea Aperpendicular tothe No.411-125, Nov.14,1944(forcylinder andsphere); hforse andRubenstein, Phys. Rev,, 54, 895 (1938) (forelhptical cylinder); L.J.Chu, RRL Report No.4,Oct. 22, 1942; Lfarion C.Gray, “Reflection ofPlane Waves from Spheres and Cylinders, ” BTL Report hfM 42-13095. 
 DOMAIN DESCRIPTIONS OF THE '02  AND ITS ENVIRON 
 SHAPED BEAM "Y SUBSTITUTING %QS       AND  INTO %Q   THE RECEIVED POWER CAN BE EXPRESSED IN TERMS OF THE  REFLECTIVITY FACTOR : AND RANGE R AS   00' C + : RRT     QF TP L\\ L N     "ECAUSE  THE RECEIVING FILTER SUPPRESSES SOME OF THE RECEIVED SIGNAL POWER   0R MUST  BE REDUCED BY  ,R  WHICH DEPENDS ON THE DETAILS OF THE TRANSMITTED SPECTRUM AND THE  RECEIVER FILTER BUT IS USUALLY A FACTOR OF ABOUT   D"  FOR A TYPICAL WAVEFORM AND hMATCHED FILTERv 3OLVING FOR THE RADAR REFLECTIVITY FACTOR : GIVES   :   ; LN K  ,R0T ' P E C S O   \+\= 0R R     WHERE THE REFLECTIVITY FACTOR IS EXPRESSED IN TERMS OF THE RECEIVED POWER AND RANGE /NE MUST BE CAREFUL TO USE CONSISTENT UNITS IN %Q  )F METER 
 41  7.1 CW Doppler Radar .......................................................................................................... 41  7.1.1 The Doppler Frequency ............................................................................................ 41  7.1.2 Quadrature Modulation ............................................................................................. 
 The principle units associated with ASV Mk. III are listed below: Modulator, type 64; Transmitter –receiver TR. 3159 or TR. 
 ( c) Vehicle. ( d) Top-hat.      (a) (b) (c) (d)  Figure 13. 
 to be jammed are known and confined to a narrow band. However, many radars are frequency-agile over a wide band as an ECCM against spot jamming. If the rate of frequency agility is slow enough, the jammer can follow the frequency changes and maintain the effect of spot jamming. 
 The Corner Reflector. -It isoften desirable tomake acompact radar target with alarge cross section. Aflat plate ofdimensions large compared toaw-avelength exhibits alarge cross section when viewed along itsnormal, because ofspecular reflection, but thecross section falls offsharply inother directions [see Eqs. 
 The former Wheeler Laboratories  developed the Coincident Phase Center Technique (CPCT)15 to remove the spectral  spread due to the velocity component perpendicular to the aperture and due to the  component parallel to the aperture. Removal of the component parallel to the aperture  uses the DPCA pattern synthesis technique described in Anderson,8 which creates two  similarly shaped illumination functions whose phase centers are physically displaced.  Removal of the component perpendicular to the aperture is accomplished by a novel  extension of this concept. 
 7), is a good example of a target shape that yields  a low value of cross section over a wide range of angles.  I • The radar cross section of a target can also be reduced by electromagnetic absorbent  materials. 5 5 One type of electromagnetic absorber is based on destructive interference. 
 brochure published byVarian, Beverly. Mass..nodate. 17.Skowron. 
 CIATING TO A SINGLE RADAR TRACKWHICH BY DEFINITION IS UNBIASED WITH RESPECT TO ITSELF )F BIASES CANNOT BE KEPT  SMALLER THAN THE 2/5   THEN AT HIGH PROBABILITIES OF DETECTION   ONE PREFERS SINGLE RADAR ASSOCIATION FOLLOWED BY TRACK 
 Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.476x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 Examples of weather radar applications for which MTI filters are used: 1. Weather Doppler Radars (NEXRAD/WSR-88)  Radars with rotating antennas that  measure precipitation rate, doppler velocity, and turbulence. 
 To dynamically make this com - promise, the filter weighting can be adaptive to the main-beam clutter level by mea - suring the peak return level (usually main-beam clutter) over the IPPs, and selecting  or computing the best weighting to apply across the CPI. Another technique that  is applicable to high-medium and high PRF is to generate a hybrid filter weight - ing by convolving two weighting functions. The result is a filter with significantly  less weighting loss and low far-out sidelobes, but at a cost of relatively high near-   in sidelobes. 
 9. R. L. 
 70 Substituting Eq. ( 13.21) into ( 13.18) with I K j2 = 0.93 yields  j5 _2.4P 1Grr1.6  10_8 ,-R2A2 X ( 13.22)  where r is in mm/h, R and ,1. in meters, r in seconds and P1 in watts. 
 6.3 Atmospheric Absorption Nois e  In a stationary condition all bodies, which absorb energy, re- radiate the same energy as noise  power.  This is the radiation theory of black bodies.  Would this not be the case then some  objects would warm themselves and others would cool themselves down . 
 By the end of the mis - sion, Magellan  had returned more data than all prior planetary missions combined.  The radar operated in three modes—imager, altimeter, and radiometer—interleaved  during each pass.102 The X band data downlink supported data rates of 268 kbit/s or  115 kbit/s. The 3.7-m diameter high-gain antenna was used for both the radar and  for telecommunications. 
 ERED IS SPATIALLY ORIENTED  RESULTING IN BEAM 
 SEC. 4.2] POWER ANDINFORMATION RATE 121 separate transmitter and receiver. The V-beam radar isthus anauthen- ticexample oftheuseofaseparate radar system toovercome ascanning speed limitation. 
 ZERO SIDELOBE DIRECTED TOWARD NADIR  THE RESULTING REFLECTION COULD APPEAR IN  THE IMAGE 4HE MAIN STRATEGY IS TO AVOID THE AMBIGUITY BY CHOOSING THE 02& SO THAT THE NADIR RETURN ARRIVES AT THE SAME TIME THAT THE RADAR IS TRANSMITTING 4HIS TIMING PLACES A FURTHER CONSTRAINT ON THE PULSE REPETITION FREQUENCY )T TURNS OUT THAT THE NADIR RETURN MAY NOT BE AVOIDABLE IF OTHER CONSTRAINTS OVERRIDE THE AVAILABLE 02& OPTIONS 4HIS OCCURS  FOR EXAMPLE  IF THE DRIVING REQUIREMENT IS 3CAN3!2  WHICH HAS ITS OWN SET OF CONSTRAINTS ON 02&    -ULTIPLICATIVE NOISE  A STANDARD SPECIFICATION IN SYNTHETIC A PERTURE RADAR  INCLUDES UNWANTED CONTRIBUTIONS SUCH AS  AMBIGUITIES AND QUANTIZATION NOISE THAT ARE PROPORTIONAL TO THE STRENGTH OF THE RECEIVED SIGNAL. 
 Most ECDIS equipment can optionally show radar-derived data,  normally as tracked target vectors but sometimes as the radar image itself. This data  is obtained from the radar processor via a digital interface, giving an apparent conver - gence of ECDIS and radar displays. Certainly, this is true at a basic design level, but  IMO is keen to differentiate between the two. 
 GAMMA MODEL FOR CLUTTER REFLECTIVITY  4HE ANTENNA BEAM IS POINTED AT THE GROUND CORRESPONDING TO THE  RANGE OF THE TARGET !T LONGER RANGES SMALL LOOK 
 123. Knittel. G. 
 P., and H. A. Mayer: " Radar Target Detection," Academic Press, New York, 1973. 
 The reduction in intensity as the rays diverge  (spread away) from the point of reflection can be calculated from the curvatures  of the reflecting surface and the incident wave at the specular point , which is that  point on the surface where the angle of reflection equals the angle of incidence.  The principal radii of curvature of the surface are measured in two orthogonal  planes at the specular point, as shown in Figure 14.17. When the incident wave is  planar and the direction of interest is back toward the source, the geometric optics  RCS is simply  s=πa a1 2 (14.8) where a1 and a2 are the radii of curvature of the body surface at the specular point. 
 SIZE DISTRIBU 
 The change in the Doppler frequency leads to a linear frequency modulation (see Figure 9.5).  In Sec.  8.8 it has been shown for analog pulse  compression, that through the Fourier transformation of a linear FM signal in the time domain a compressed signal with the envelope sin x/x results. 
 Figure2.19SameasFig.2.18exceptfre­ quency is9225MHz(Xband).VHand HVrepresent cross-polarized components. (FromOlinandQueen.30)-40A-180' -10--20-3010 Elewahan aSjl8etanglerdcgIreIrTVH ITvv 00--·--=-10=----"2=0--:· 3"'0---:-40 00 lblb10. TfiE RADAR EQUATION 43  Table 2.la Radar cross section (square meters) of the T-3866  Head-on aspect ( f 1.0 degree)  X1.r. 
 The principal function ofthelocking-test channel, asitsname implies, istoreveal any unsteadiness intheoriginal locking pulse orany failure of thecoherent oscillator tolock properly. Anattenuator and appropriate switches can bebuilt into the input circuits ofthetwo-channel amplifier topermit measurement ofdelay-line attenuation. Checking and adjustment ofcancellation can bedone while theradar isoperating bymixing adelayed video pulse with the signals before cancellation. 
 The measiirements made  by the two systems are not the same; consequently, the characteristics of the antenna beams  will also be different, In the amplitude-comparison monopulse the two beams arc offset, Illat is,  point in slightly different directions. This type of pattern may be generated by using one  reflector dish with two feed horns side by side (four feed horns for two coordinate data). Since  the feeds may be placed side by side, they could be as close as one-half wavelcngtl~. 
 HORIZON DETECTION OF TERRESTRIAL TARGETS AT RANGES OF THOUSANDS OF KILOMETERS  CAN BE ACHIEVED BY RADARS OPERATING IN THE HIGH 
 The largest echo source in the SR-71 nose-on region is probably the  engine intakes because they are thrust well forward of the wing leading edges. The  intakes of the F-117 Nighthawk, by contrast, are installed above the wing and well aft  of the leading edge; they are the little black diamonds seen in the nose-on view of the  F-117 shown in Figure 14.31. As such, the intakes are shielded from ground-based FIGURE 14.29  The objects whose radar cross sections  are plotted in Figure 14.28. 
 At the higher radar frequencies,  attenuation may not always be small and may have to be taken into account. In addition to the  losses in the transmission line itself, an additional loss can occur at each connection or bend in  the line and at the antenna rotary joint if used. Connector losses are usually small, but if the  connection is poorly made. 
 Conf ., vol. 23, 1980.  7. 
 TO 
 WEIGHT SUPERCONDUCTORS NOT AVAILABLE AT THIS WRITING  )T ALSO REQUIRES VERY LOW VOLTAGE DROP RECTIFIERS AND REGULATORS #OOLING IS GENERALLY A SIGNIFICANT PERFORMANCE BURDEN 5SUALLY  THE POWER SUPPLIES ARE DISTRIBUTED TO IMPROVE RELIABILITY AND FAULT TOLERANCE /FTEN  POWER CONVERTERS ARE OPERATED AT SWITCHING FREQUENCIES UP TO SEVERAL HUNDRED MEGAHERTZ TO REDUCE THE SIZE OF MAGNETICS AND FILTER COMPONENTS  AND SOMETIMES  THE SWITCHING FREQUENCIES ARE SYNCHRONIZED TO THE RADAR MASTER CLOCK x°ÓÊ /9*  Ê --" -Ê  Ê " 
 10, pp. 1402–1413, October 1996. 64. 
 ART HIGH 
 POWER  PHASE SHIFTERS OR TRANSMIT MODULES WITH LOW 
 This may be accomplished with a  .. keep-alive," which is a weak d-c discharge that generates electrons which diffuse into the TR  where they act to trigger the breakdown once RF power is applied. The keep-alive generates  noise just as any other gas-discharge device. 
 /Ê ,"--Ê- 
 The configuration of one channel is rather simple.  Figure 14.3 shows the configuration.    . 
 In some applications of CW radar it is of interest to know whether  the target is approaching or receding. This might be determined with separate filters located  on either side of the intermediate frequency. If the echo-signal frequency lies below the carrier,  the target is receding; if the echo frequency is greater than the carrier, the targel is approaching  (Fig. 
 18.56  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 Flight Systems.  RadScat131 (Table 18.8) was the name given to the radiometer/ scatterometer portion of the S-193 Ku band instrument aboard Skylab. The top-level  objectives of this experiment were (1) to provide the near-simultaneous measurement  of microwave backscatter and emissivity of land and ocean on a global scale and   (2) to provide engineering data for use in designing space radar altimeters. 
 The output power Pno is thus "referred" to the system input (the antenna terminals), and Ts is actually the system input noise temperature. The product W8Bn is thus the system output noise power referred to the antenna terminals. Each two-port transducer of the receiving-system cascade can be regarded as . 
 Theycancachbeapplicdindividually. ifdesired.toanytracking radartoimprove theaccuracy oftrack. High-range-resolution monopulse.66Ithasbeennotedpreviously inthischapter thatthe prescnce oflTlultiple scatterers withintherange-resolution celloftheradarresultsinscintilla­ tion,orglint.whichcallintroduce asignificant error.Theuseofaradarwithhighrange- radarlocation approx.radar corresponding zero angleerrorvoltagerangevideo anglevideoQ) "t:7 ttWV-2 superconste110tion timeI I I I I I I I I I I I \ -1- / / /L_ Figure5.20Rangeandanglevideooblained withtheNRLHighRangeResolution Monopulse (HRRM) radar.ThetargetisaSuperConstellation aircraninflight.Notethattheanglevideoindicates towhatside oftheradarbeamaxisarelocatedtheindividual scatterers whichareresolved inrange.Theradar opcrated atXhandwitha7-n-diameter antenna andapulsewidthof3nanoseconds.66. 
 J. Remote Sens. 2012 ,14, 2203–2213. 
 However, iftheechoesfromthevariouspartsofalargetargetaredisplayed withoutcollapsing lossandiftheoperator knowsthegeneralshapeofthetarget,therewillbe little,ifany,lossindetectability. Antenna beamwidth.Thediscussion aboveregarding thebenefitsandlimitations oftheshort pulsealsoapplytotheazimuth beamwidth. Theuseofhighresolution inangle{ndjor range istheprincipal method available fordetecting afixedtargetinclutter,assuming thetarget "crosssectionperunitarea"isgreaterthanthatofclutter (10.Toonarrowabeamwidth, just astoonarrowapulsewidth,isnotdesiredsinceitcanalsoaltertheclutterstatistics inan unfavorable manner. 
 Automatic detection is also an  important part of automatic detection and track (ADT) systems, as discussed in Sec. 5.10. The  automatic detector has also been called plot extractor and data extractor. 
 After passing by the cavity gap, the beamlets  reenter their individual drift channels and propagate in isolation from one another.  Such klystrons are called multiple-beam klystrons,  or MBK . It has been said10 that the  number of beamlets in an MBK might be from 6 to 60. 
 TO 
 Thesuperiority ofthemonostatic radarevenseemstoextendtotheapplication oftheradar fence.Although lessequipment isneededwiththebistatic-radar fence,thisadvantage isoffset toalargeextentbythedifficulties involved inextracting thetarget'sposition. Thebistaticradardeserves creditforitshistorical roleintheearlydaysofradarinleading tothedevelopment ofmonostatic radar.Itshouldbegivenconsideration, alongwithother possible radartechniques, inthoseapplications wheresomeinherent characteristic maybea desirable attribute orwhentheapplication doesnotrequirecomplete targetinformation. But asameansforthegeneraldetection andlocation oftargets,itisovershadowed by,itsoffspring, themonoStatic radar. 
 HAND SIDE OF THE ILLUSTRATION  AFTER THE ELECTRON BEAM HAS GIVEN UP ITS 2& ENERGY AT THE OUTPUT CAVITY ! LOW 
 IRE.) . PROPAGATION OF RADAR WAVES 459  represents the approximate boundary between the interference· region and diffraction region.  Any target to the right of curve 6 may be considered to be within the diffraction region. 
 TIONS ARE MORE OFTEN USED TO  DESCRIBE THE VARIATIONS BETWEEN DIFFERENT RETURNS FROM AN  AREA  RATHER THAN FADING 4HEY MAY BE THOUGHT OF AS DESCRIBING WHAT HAPPENS WHEN THE AREA CONTAINS DIFFERENT  R  S  AND THE DISTRIBUTION FOR EACH IS 2AYLEIGH  "ECAUSE  OF THIS  THE RANGE OF VARIABILITY MAY BE EVEN GREATER THAN THE  D" FOR A 2AYLEIGH DISTRIBUTION &ADING 
 BEAM TUBES  SO THEIR APPLICATION FOR -4) RADAR HAS BEEN LIMITED "ECAUSE OF THE #&!S LOW GAIN  THE CROSSED 
   !RLINGTON  6!    PP  
 Ilit'E 7'rtrtr\., vol. MTT-13,  pp. 785-788, November, 1965. 
 '.  Figure 4.20 Frequency-response characteristic of an MTI using range gates and filters. --t + -  ---t 1  Bandposs  (Doppler)  filter  -t -  - -+- Threshold  Threshald Low poss  filter Threshold  (integrator) - Full -wave  lineor  detector -t-  118INTRODUCTION TORADAR SYSTEMS RangeBoxcarBandpass Full-wove Lowpass--gate~-(Doppler)r-linear4--- tilter I~ThresholdL_ NO.1generatorfilter detector (integrator) RangeBoxcarr-gater--generatorr----f----Threshold f-- No.2 ~ PhoseRange ~--detectorr-f--gater----- -- NO.3 --.. 
 Another limitation is the loss in energy and increase in sidelobe level caused by the  sliadowing produced by the steps. The effect of the steps may be minimized by using a design  with large 111). on the order of 1 or niore. 
 This provides a stable reference in the absence of clutter.  An input from the aircraft inertial navigation system and the antenna servo provide a  predicted doppler offset. These inputs allow the TACCAR system to provide a narrow- bandwidth correction signal. 
 INGLY  IS THE SAME WIND 
 One of the beams is tilted slightly upward,  while the other is tilted slightly downward, to achieve the squint needed for amplitude-  comparison monopulse in elevation. Therefore the horizontal projection of the antenna pat-  terns is that of a phase-comparison system, while the vertical projection is that of an  amplitude-comparison system.  Both the amplitude-comparison-monopulse and the phase-comparison-monopiilse  trackers employ two antenna beams (for one coordinate tracking). 
 358–361, 1985. 156. M. 
 A Novel Multi-Angle SAR Imaging System and Method Based on an Ultrahigh Speed Platform. Sensors 2019 ,19, 1701. [ CrossRef ][PubMed ] 2. 
 BEAM ANTENNA             % "&$!$"%      
 Nevertheless, without special care the actual  spectrum envelope might be even worse than this, depending on tube characteristics,  as a result of phase modulation during the finite rise and fall of practical modulator  and RF drive pulse shapes. In these cases, either the leading and trailing edges must  be appropriately tailored, or else (in linear-beam tubes) the RF drive may be withheld  during the rise and fall time. Although this may slightly reduce apparent efficiency, it  should be noted that energy outside the approximately 1/ t generated during rise and  fall with the RF drive present is not utilized by the receiver anyway . 
 Reasonably long life has been demonstrated with CF As. Operation for greater than 10,000  hours is not unusual in some tubes.17 The good phase stability and short electrical length of  CF As make it possible to operate tubes in parallel to achieve greater power than available  from a single tube, as well as provide redundancy in the event of a single tube failure. The CF A  behaves as a saturated amplifier rather than as a linear amplifier. 
 The gains Gt and Gr are defined as the power gains of the antennas in the maximum-gain direction. If a target of interest is at an elevation angle not in the beam maxima, that fact is accounted for by the pattern propagation factors Ft and Fr, discussed in Sec. 2.6. 
 First, we proposed a new data augmentation method which can keep important information while increasing the amount of data and achieve the requirements of the dataset. Then, by coupling transfer learning with the processed data, we can get good performance in classiﬁcation. When dealing with a small training dataset, the method can successfully enlarge the training datasets. 
 Ithas notfound wide usefort woreasons: (1)theaccom- panying increases inminimum detectable signal power, explained in Sec. 211, and (2)thefact that themethod discards alarge fraction ofthe information available intheradar system, therange information. Aneven closer approach tothe television method has been visual- ized, inwhich the proposed radar receiving system isbuilt something like atelevision camera. 
 Other letter bands have been used for describing the electromagnetic spectrum; but  they are not suitable for radar and should never be used for radar. One such designation  uses the letters A, B, C, etc., originally devised for conducting electronic countermeasure  exercises.7 The IEEE Standard mentioned previously states that these “are not consistent  with radar practice and shall not be used to describe radar-frequency bands.” Thus, there  may be D-band jammers, but never D-band radars. 1.6 EFFECT OF OPERATING   FREQUENCY ON RADAR Radars have been operated at frequencies as low as 2 MHz (just above the AM broad - cast band) and as high as several hundred GHz (millimeter wave region). 
 diameter) arestill toosmall, and itisdesirable toprovide anenlarged presentation. Since atmost scanning rates phosphorescent screens donot provide enough light forprojection, itisnecessary todevise special methods. Of those used todate, one involves the projection ofaphotograph ofthe PPI orother scope, which isdeveloped and projected inafew seconds by special techniques; theother involves opaque projection from theskiatron screen (see Sec. 
 The coarse range scope shows allranges outtoamaxi- mum of32,OOO yd.and thefine scope shows amagnified trace ofa2000-yd -...— FIG.6.37.—SCR-584 inoperating position. interval which can bechosen anywhere \vithin the 32,000 yd. Markers geared together at1to16and driven bytherange handwheel areinfront ofthese tubes. 
  DEVELOPERS CONTRIVED AN  EGG 
 It covers swaths on both sides of the satellite ground track.  The near edge of these 500-km swaths are offset 384 km from nadir, spanning 25 °–– 65° incidence. The 0.57 dB radiometrically accurate data are averaged to achieve Kp  from 3% (high up-wind speed) to 10% (low speed, cross-wind aspect). 
 A. Figure 13.6 Composite rough-surface model of tile sea  with the small resonant water waves riding on top of tile  larger water waves, resulting in a tilting of the resonant  , waves from the horizontal.  UHF radar (A = 70 cm) at zero degrees grazing angle responds to water waves of length  35 cm. 
 UNDERSTOOD  AND AS A MASS 
 Mullin, C. R., et al.: A Numerical Technique for the Determination of the Scattering Cross Sections of Infinite Cylinders of Arbitrary Geometric Cross Section, IEEE Trans., vol. AP-13, pp. 
 For alldisplays except rotating-coil PPI’s, the so-called “substitution” method illustrated inFig. 13.35 can beused. From time totime control ofthedisplay isswitched from theregular angle data transmitter toone that can besetbythe operator. 
 Qin, X.; Yang, M.; Wang, H.; Yang, T.; Lin, J.; Liao, M. Application of high-resolution PS-InSAR in deformation characteristics probe of urban rail transit. Acta Geod. 
 SISTOR CHANNEL TO STOP FLOWING 4HUS  THE TRANSISTOR IS hPINCHED 
 Thesesequences arecalledlinearsincetheyobeythesuperposition theorem. Thepeaksidelobe levelsofthelinearrecursive sequences andofBarkercodesgreater thanlength5arelowerthanthe-13.2dBofthelinearFMwaveform. However, thesidelobes oftheBarkercodescanbefurtherlowered byemploying amismatched filterandaccepting a slightlossinthepeaksignal-to-noise ratio.31 Comparison oflinearFMandphase-coded pu~ecompression. 
 104-109, February, 1946.  4. Bonner, H. 
 It does not  include several devices often found in radar, such as means for automatically compensating the  receiver for changes in frequency (AFC) or gain (AGC), receiver circuits for reducing interfer­ ence from other radars and from unwanted signals, rotary joints in the transmission lines to  allow movement of the antenna, circuitry for discriminating between moving targets and  unwanted stationary objects (MTn and pulse compression for achieving the resolution benefits  of a short pulse but with the energy of a long pulse. If the radar is used for tracking, some  means are necessary for sensing the angular location of a moving target and allowing the  antenna automatically to lock-on and to track the target. Monitoring devices are usually  included to ensure that the transmitter is delivering the proper shape pulse at the proper  power level and that the receiver sensitivity has not degraded. 
 Peak pulse power using these tubes was about 150 kw; later, itwas increased toabout one megawatt. Both transmitters and receivers were massive and elaborate. They were housed inseparate bombproof buildings, usually about half amile apart. 
 SEC. 6.10]PPI RADAR FOR SEARCH, CONTROL, AND PILOTAGE 183 showed instantaneously only those targets located inanarrow azimuth sector, made useofthepersistent property ofCRT screen phosphors to preserve from one scan toanother the target signals returned onthe most recent scan. The PPI thus presents acontinuous map-like display ofalltargets inthefield ofview ofitsradar, and permits attention tobe concentrated onparticular targets without thepenalty oflosing sight of thegeneral situation. 
 ;   =   4HE RESULTING DISPERSION DISTORTS THE RADAR MODULATION  WHICH MUST BE COMPENSATED BEFORE PULSE COMPRESSION 4HE  
 In principle the parabolic torus can be scanned 180°, but because of beam spillover near  the end of the scan and self-blocking by the opposite edge of the reflector, the maximum scan  angle is usually limited to the vicinity· of 120°.  Only a portion of the parabolic-torus is illuminated by the feed at any particular time.  This may appear to result in low aperture utilization or poor efficiency since the total physical  area is not related in a simple manner. 
 PLE  A VERTICAL SOUNDING OF THE IONOSPHERE  KM DOWNRANGE HAS BEEN USED AS THE ELECTRON DISTRIBUTION FOR ALL ONE 
 Hydrogen thyratrons, ignitrons, and spark-gaps have been  used as switches. The sudden surge of current due to a fault in a protected power tube is sensed  and the crowbar switching is actuated within a few microseconds. The current surge also  causes the circuit breaker to open and deenergize the primary source of power. 
 1973. 116.Schaefer, G.W.:RadarOnservations orInsectFlight,chap.8,or"lnsect Flight," R.C.Rainey(ed.). Blackwell Scientific Puhlications. 
 URES CITED IN 4ABLE  SHOW THAT THE RATIO OF WAVEFORM BANDWIDTH TO 2& BANDWIDTH FOR 4/0%8 IS ON THE ORDER OF  4HE 4/0%8 ALTIMETER DESIGN IS DESCRIBED MORE COMPLETELY IN THE OPEN LITERATURE   'EOSAT 'EODETIC -ISSION   2ADAR ALTIMETRIC DATA ARE THE BASIS FOR STATE 
 ONSTRATED 5SUALLY  A VERY DETAILED THERMAL ANALYSIS USING THE FINITE ELEMENT METHOD IS REQUIRED TO QUANTIFY THESE RELATIONSHIPS DURING TRANSISTOR AND AMPLIFIER DESIGN "ACKGROUND AND DESCRIPTIONS OF THE COMMON THREE 
 It also performs optimum filtering of radar angle-error- detector output to generate an error trend from which it can update the assumed set   ch09.indd   25 12/15/07   6:07:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 
 AVERAGED  RANG !T LOWER RADAR FREQUENCIES  AND IN LESS TURBULENT ATMOSPHERE   " MAY BE SMALLER  AND PROPORTIONATELY LONGER TIME  SAMPLES ARE NECESSARY THUS  FOR SHORT TIME SAMPLES OF RADAR PERFORMANCE  SIGNIFICANT STATISTICAL VARIATIONS MUST BE EXPECTED 4O CONVERT  R ANG EXPRESSED IN LINEAR UNITS MEASURED AT THE TARGET TO ANGULAR UNITS FOR  A RADAR AT RANGE R  THE FOLLOWING RELATION MAY BE USED RANG ANGULAR MILS    RANG M RKM  "ECAUSE THE ANGULAR ERRORS CAUSED BY ANGLE NOISE ARE INVERSELY PROPORTIONAL TO  RANGE  ANGLE NOISE IS OF CONCERN MAINLY AT MEDIUM AND CLOSE RANGES 4HE RESULTANT TRACKING NOISE CAN BE REDUCED BY LOWERING THE SERVO BANDWIDTH TO REDUCE THE RADARS ABILITY TO FOLLOW THE HIGHER 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°£Î TENTH PERCENTILE &URTHERMORE  ONE CAN USE FEEDBACK BASED ON SEVERAL SCANS OF DATA  TO CONTROL  + IN ORDER TO MAINTAIN A DESIRED  0FA ON EITHER A SCAN OR A SECTOR BASIS 4HIS  DEMONSTRATES A GENERAL RULE TO MAINTAIN A LOW  0FA IN VARIOUS ENVIRONMENTS  ADAPTIVE  THRESHOLDING SHOULD BE PLACED IN FRONT OF THE INTEGRATOR )F THE NOISE POWER VARIES FROM PULSE TO PULSE AS IT WOULD IN JAMMING WHEN FRE 
 The X band and S band communications  system used a despun antenna ( ∼1 m diameter dish). The radar altimeter provided many  years of data with a height accuracy of 150 m, which was the best available information  on Venus’ surface figure until Magellan . The altimeter’s waveform strength and shape  were analyzed to estimate surface electrical conductivity and meter-scale roughness  properties.99 The spacecraft’s 24-hour orbit was highly elliptical ( ∼200 km periapsis  and ∼22,900 km apoapsis†  for most of the mission). 
 PONENTS THAT CAN BE REALIZED THROUGH THE USE OF THIS TECHNOLOGY CAN BE EMPLOYED TO CREATE SYSTEM ARCHITECTURES THAT ARE DIFFICULT  IF NOT IMPRACTICAL  TO DESIGN WITH OTHER  LESS INTEGRATED TECHNOLOGIES 4HE --)# DESIGN APPROACH UTILIZES ACTIVE AND PASSIVE DEVICES THAT HAVE BEEN MANUFACTURED BY USING A SINGLE PROCESS !CTIVE AND PASSIVE CIR 
 DIMENSIONAL  INFORMATION CAPACITY OF THE RADAR IN THE 3HANNON SENSE 4HIS PRINCIPLE WAS APPLIED WITH GREAT PROFIT TO THE  -AGELLAN 3!2 DESIGN    AS ILLUSTRATED BY 4ABLE  &ROM THAT TABLE  ONE CAN VERIFY THAT THE IMAGE QUALITY OF -AGELLAN DATA VARIED BY NO MORE THAN  ^o POLE TO POLE  IN SPITE OF LARGE VARIATIONS  IN RADAR RANGE  INCIDENT ANGLE  AND GROUND RANGE RESOLUTION $ATA 2ATE  -AGELLAN 3!2 DATA WERE RELAYED FROM 6ENUS TO %ARTH VIA THE $3.  4HIS MAJOR COMMUNICATION SYSTEM IMPOSED A WORKING LIMIT OF ABOUT  KBITS ON THE 3!2 DATA TELEMETRY 7HEREAS THIS MAY SEEM RATHER LARGE  IT IS MINUSCULE BY .   30!#% 
 ON VIEW  WITH A SINGLE ENGINE AND NO SIGNIFICANT REFLECTORS ATTACHED TO THE WINGS WILL HAVE A R ANG OF APPROXIMATELY  ,  WHEREAS LARGER AIRCRAFT WITH AN OUTBOARD ENGINE AND  POSSIBLY WING TANKS WILL HAVE A  RANG APPROACHING THE VALUE OF , 4HE AIRCRAFT SIDE  VIEW ALSO TENDS TOWARD THE VALUE OF  , BECAUSE OF A MORE CONTINUOUS DISTRIBUTION  OF REFLECTING AREAS %STIMATION OF ANGLE SCINTILLATION RMS ERROR IN UNITS OF TARGET SPAN CAN BE MADE BY RELATING THE APPROXIMATE TARGET DISTRIBUTION IN &IGURE  WITH ACTUAL AIRCRAFT CONFIGURATIONS 4HE VALUE OF  R ANG FOR A COMPLEX TARGET IS ESSENTIALLY A FIXED VALUE REGARDLESS OF 2&  FREQUENCY  IF A TARGET SPAN OF AT LEAST SEVERAL WAVELENGTHS IS ASSUMED AND IS INDEPENDENT OF THE RATE OF RANDOM MOTION OF THE TARGET (OWEVER  AS DESCRIBED LATER  THE SPECTRAL DISTRIBUTION OF ANGLE 
 The squareness is measured hy the  ratio of the remanent magnetization to the saturation magnetization, which with practical  ferrite materials might typically be about 0.7.  The amount of differential phase shift depends on the ferrite material and the length of the  toroid. A digital latching phase shifter is obtained by placing in cascade a nuinber of separate  toroids of varying length. 
 %3, 3!4#/- 7ORKBENCH '5)  OFFSET 'REGORIAN REFLECTOR MODEL AND PATTERN. £Ó°ÎÈ  2!$!2 (!.$"//+  )NSTALLATION )S A 3IGNIFICANT -ECHANICAL $ESIGN $RIVER  4HE PLATFORM IS GEN 
 Hence scanning a simple p~raboloid antenna by  scanning the feed is possible, but is generally limited in angle because ol the deterioration in  the antenna patter11 after scanning but a few beamwidths off axis.  Spherical rellcctors. II' t11c paraboloid reflector is replaced by a spherical-reflector surface, it is  possible to achieve a wide scanning angle because of the symmetry of the sphere. 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar.  TRACKING RADAR  9.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 A similar X- and Ka-band system was developed by Hollandse Signaalapparaten of  the Netherlands for tactical application. The land-based version called FLY-CATCHER  is part of a mobile anti-air-warfare system.25 Another version, GOAL-KEEPER, is for  a shipboard anti-air-warfare application for the fire control of Gatling guns.26 Both  systems take full advantage of the two bands to provide precision tracking in multipath  and electronic-countermeasures environments. 
 93 -96, IEEE Cat. no. 76 CH l l21-3AP. 
 ASPECT TARGET PERFORMANCE IS USUALLY DESIRED  SINCE THESE RETURNS COMPETE WITH TARGETS OF INTEREST )N A HIGH 
 FLIGHT  HORIZONTAL DUE TO ELIMINATION OF GIMBAL SWING SPACE   HIGHER RADIATED POWER DUE TO LOWER LOSSES AND BETTER EFFICIENCY  AND  LOWER LOSSES BEFORE THE LOW 
 simultaneously fromasingleaperture. Inprinciple, anN-element arraycangenerate N independent beams.Multiple beamsallowparalleloperation andahigherdataratethancan beachieved fromasinglebeam.Themultiple beamsmaybefixedinspace,steeredindepen­ dently,orsteeredasagroup(asinmonopulse anglemeasurement), Themultiple beamsmight begenerated ontransmit aswellasreceive.Itisconvenient insomeapplications togenerate themultiple beamsonreceiveonlyandtransmit withawideradiation patternencompassing thetotalcoverage ofthemultiple receiving beams.Theabilitytoformmanybeamsisusually easieronreception thantransmission. Thisisnotnecessarily adisadvantage sinceitisausefuI methodofoperating anarrayinmanyapplications. 
 The beauty of the architecture is that overflows are allowed  and compensated for by the comb section, as long as there are enough bits in the adders  to represent the maximum expected output value and the filter is implemented using  two’s complement arithmetic. As described by Harris,10 the number of bits required in  the adders ( bADDER ) is given by  bADDER  = bDA TA + CEIL[log2(GAIN)]  where bDA TA is the number of bits in the input data and CEIL[ ] indicates rounding the  number in the brackets to the next highest integer. GAIN is given by  GAIN = RK  where R is the decimation factor and K is the number of stages in the filter, resulting in  bADDER  = bDA TA + CEIL[log2(RK)]  For example, assume we have 12-bit input data ( bDA TA = 12) and a 3-stage CIC filter  (K = 3) that decimates the sample rate by a factor of 10 ( R = 10). 
 42 
 The nuisance of“rain clutter,” which the latter effect issometimes called, ismost severe when the radar cross section ofthe desired target issmall. Other factors that determine the intensity ofthe rain echo relative tothat ofthetarget echo arethebeamwidth, pulse length, and }ravelength oftheradar, thedistance tothetarget, and thenumber and size ofthewater drops intheneighborhood ofthetarget. Inthecase of aradar setusing apencil beam orasimple fanbeam, these factors enter theproblem asfollows: -()R’A~ CT.Voo Average rain-echo intensity =_ _ Target-echo intensity .1” 2T’(24) ICI~~ndo,v “istheBritish andmost commonly used code nanle forconducting foilorsheet cutintopieces ofsuch asizethat each piece resonates asadipole atenemy radar frequency. 
 The use of  circular polarization to reduce the radar echo from symmetrical raindrops relative to the echo  from aircraft, as described in Sec. 13.8, takes advantage of the differences in target response to  different incident polarizations. ·  For complete knowledge of the effect of polarization, the polarization matrix must be  determined. 
 Tlie shape of a radome for a ground-based antenna is usually a portion of a sphere. The  .;l~ltcre is a good ~ilecllariical structure and offers aerodynamic advantage in high winds.  Precipitation particles blow around a sphere rather than impinge upon it. 
 The discrete frequency-shift, or time{requency coded, waveform is generated by dividing a  long pulse into a series of contiguous subpulses and shirting the carrier frequency from  sub pulse to subpulse.16•33 The frequency steps are separated by the reciprocal or the subpulse  width. A linear stepping of the frequency gives an ambiguity diagram more like the ridge of the  linear FM. When the frequencies are selected at random, the result is a thumbtack ambiguity  diagram. 
 RECEIVE ELEMENTS  SHOULD BE OPERATED AT CONSTANT DUTY CYCLE 4HIS PERMITS THE TRANSMITTER POWER SUPPLY TRANSIENT EFFECTS TO BE IDENTICAL PULSE TO PULSE AND ALSO  PARTICULARLY APPLICABLE TO SOLID 
 The technique . THE RADAR EQUATION 59  for computing scanning loss is similar in principle to that for computing beam-shape loss.  Scanning loss can be important for rapid-scan antennas or for very Jong range radars such as  those designed to view extraterrestrial objects. 
 The magnetron and the crossed-field amplifier are devices wllich utilirz the  properties of electron streams in crossed electric and magnetic fields. The klystron and the  traveling wave tube are of a different family known as linear beam tubes. i  Radars at VHF and UHF have often employed grid-controlled t riode.and tet rode t lrbes. 
 l 0  0 I .c u w -3 I • I ,  I !.1 t I I I I  I , ... I I  I  20 -r-- Measured  Calculated  30 40 50 60  Angular orientalion B THE RADAR EQUATION 35  70 80 90  Figure 2.IO Backscatter cross section or a long thin rod. (From l;eters,26 IRE Trans.)  down the length of the object and reflect from the discontinuity at the far end. 
 Vol. 111," R. C'. 
 The gain is reduced by about 10 dB in so doing, but the improved  electron bunching results in greater efficiency and in 15 to 25 percent more output power.7  Broadbanding of a multicavity klystron may be accomplished in a manner somewhat analo-  gous to the methods used for broadbanding multistage IF amplifiers, that is, by tuning the  individual cavities to different frequencies. This is known as stagger tuning. Stagger tuning of a  klystron is not strictly analogous to stagger tuning a conventional IF amplifier because inter-  actions amopg cavities can cause the tuning of one cavity to affect the tuning of the others. 
 The particular waveform transmitted by a  radar is chosen to. satisfy the requirements for ( 1) detection, (2) measurement accuracy,  (3) resolution, (4) ambiguity, and (5) clutter rejection. The ambiguity function and its plot, the . 
 E. F. Knott, “RCS reduction of dihedral corners,” IEEE Trans ., vol. 
 The methods used and the constants chosen forthe setshould beselected insuch a way astominimize theeffects oftheinherent fluctuations. The elimina- tion ofspurious variations islargely amatter ofcareful engineering design. Another factor tobeconsidered inthechoice ofsystem parameters is that since different radial velocities produce different changes inrelative phase from pulse topulse, certain velocity intervals are much more effective than others inproducing large uncanceled signals. 
 £K K    &OR !LERT#ONFIRM DETECTION PERFORMANCE  THE  0D FOR THE !LERT DWELL AND THE  0D  FOR THE #ONFIRM DWELL ARE INDIVIDUALLY COMPUTED AS A FUNCTION OF 3.2 #ARE MUST  BE TAKEN TO NORMALIZE THE 3.2 TO ACCOUNT FOR DIFFERENCES IN DOPPLER FILTER BANDWIDTH BETWEEN THE !LERT AND #ONFIRM WAVEFORMS 4HE MULTIPLICATION OF NORMALIZED PROB 
 113.Atlas.D.:Meteorological "Angel" Echoes.J.Meteorol ..vol.16.pp.6-11,February, 1959. 114.George. S.F.:TheDetection ofNonnuctuating Targets inLog-Normal Clutter, NavalResearch I.a!wrator}' Report6796.Washingtoll, D.C.,Oct.4,1%1\. 
 TIME METEOROLOGICAL DOPPLER RADARS v  *  !TMOS /CEANIC 4ECHNOL  VOL   PP n    2 * +EELER AND # ! (WANG  h0ULSE COMPRESSION FOR WEATHE R RADAR v IN  )%%% )NT 2ADAR #ONF    7ASHINGTON  $#    PP n.   -%4%/2/,/')#!, 2!$!2   £°{x   ! -UDUKUTORE  6 #HANDRASEKAR  AND 2* +EELER  h0ULSE COMPRESSION FOR WEATHER RADARS v  )%%% 4RANS ON 'EOSCI 2EM 3ENS  VOL   PP n     & /(ORA AND *  +EELER  h#OMPARISON OF PULSE COMPRESSION   WHITENING TRANSFORM SIGNAL PRO 
 NIQUE IS ANALOGOUS TO THE METHOD BY WHICH WE HUMANS USE OUR TWO EYES TO HELP  ESTIMATE THE DISTANCE OF THE OBJECTS THAT WE SEE )N FACT  THE TWO 3!2 IMAGES MAY BE PRINTED ON THE SAME PAGE USING TWO DIFFERENT COLORS  WITH THE VIEWER USING SPECIAL GLASSES SO THAT THE LEFT EYE SEES ONLY ONE IMAGE AND THE RIGHT EYE ONLY THE OTHER AND THE BRAIN PROCESSING THE TWO TOGETHER SO THAT THE SCENE IS PERCEIVED IN $ )NTERFEROMETRIC 3!2 )N3!2  FOR 4ARGET (EIGHT -EASUREMENT  )NTERFEROMETRIC 3!2  )N3!2     ALSO CALLED )&3!2 SEE 3ECTION  OF #ARRARA ET AL AND !DAMS ET AL    WHEN USED FOR TERRAIN HEIGHT MEASUREMENT  INVOLVES TWO 3!2 IMAGES TAKEN FROM ANTEN 
 SATED FOR IN LATER STAGES OF PROCESSING 4HE INVERSE OF THIS FACTOR   FOR A LARGE NUMBER OF ITERATIONS  IS THE PRO 
 53. Berry, L. A., and M. 
 ( 12. l la) reduces to a particularly convenient relationship if d and hare measured in statute  miles and feet. respectively. 
 Tietjen8.1 8.1  Introduction / 8.1 8.2  Pulse Compression Waveform Types / 8.2 8.3  Factors Affecting Choice of Pulse Compression Systems / 8.26 8.4  Pulse Compression Implementation and Radar System Examples / 8.28   Appendix / 8.36 Chapter 9 Tracking Radar Dean D. Howard9.1 9.1  Introduction / 9.1 9.2  Monopulse (Simultaneous Lobing) / 9.3 9.3  Scanning and Lobing / 9.16 9.4  Servosystems for Tracking Radar / 9.17 9.5  Target Acquisition and Range Tracking / 9.20 9.6  Special Monopulse Techniques / 9.24 9.7  Sources of Error / 9.26 9.8  Target-caused Errors (Target Noise) / 9.26 9.9  Other External Causes of Error / 9.37 9.10  Internal Sources of Error / 9.42 9.11  Summary of Sources of Error / 9.43 9.12  Error Reduction Techniques / 9.46 Chapter 10 The Radar Transmitter Thomas A. Weil and Merrill Skolnik10.1 10.1  Introduction / 10.1 10.2  Linear-beam Amplifiers / 10.4 10.3  Magnetron / 10.14 10.4  Crossed-field Amplifiers / 10.16 10.5  Gyrotrons / 10.17 10.6  Transmitter Spectrum Control / 10.19 10.7  Grid-controlled Tubes / 10.21. 
 M. Simon, J. Omura, R. 
 The.,c+)~ ? signals received from these two towers overlap ~L_.JL fd 0 ,g 0 a-—l IO...1- 1.4.:,* “k, o’.. .-—...-J FIG. 3.6.—Successive frames ofaphotographic recording ofanA-scope trace at+sec intervals.inthe center and there show the effects ofde- structive and constructive interference. 
 BASED SYSTEM THAT IS LIMITED BY SCAN RATE  ONE SHOULD IMPROVE THE COMPENSATION PATTERN RATHER THAN USE A HIGHER 
 H., and F. Ghani: Optimum Mismatch Filters for Sidelobe Suppression, IEEE Trans.,  vol. AES-9, pp. 
 TOR MATERIALS AS   SILICON    GALLIUM ARSENIDE OR INDIUM PHOSPHIDE  AND THE   SO 
 The radar cross section of an automobile at X band is generally greater than that of an  aircraft or a boat. From the front the cross section might vary from 10 to 200 m2 at X band,  with 100 m2 being a typical value.65 The cross section increases with increasing frequency (up  to 60 GHz, the range of the measurements).  The measured radar cross section of a man has been reported32 to be as follows:  Frequency, MHz  410  1,120  2,890  4,800  9,375 a, m2  0.033-2.33  0.098-0.997  0.140-1.05  0.368-1.88  0.495-1.22  The spread in cross-section values represents the variation with aspect and polarization. 
 Mittermayer, J.; Moreira, A.; Loffeld, O. Spotlight SAR data processing using the frequency scaling algorithm. IEEE T rans. 
 (  o 1/r 2/r 3/r 4/r 5/r  Frequency  Figure 4. 7 Frequency response or the single delay-line canceler; T = delay time = 1/f,,. 108 INTRODUCTION TO RADAR SYSTEMS  Blind speeds. 
 White, J. F.: Review of Semiconductor Microwave Phase Shifters. ).'roc.. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 17.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 17.6 SAR IMAGE QUALITY It is clearly important for a SAR to produce high-quality imagery. 
 The phase and amplitude sensitivity of  transistor amplifiers to power supply ripple may impact the MTI improvement factor  that can be attained. In a multistage amplifier, the phase errors due to power supply  sensitivity of serially cascaded stages will add. In addition, careful design must take  into account interactions that can occur as a result of the many cascaded stages of  solid-state amplification. 
 II, paper 3269, 1961.  112. Hirst, H., and K. 
 V. Hill, with Professor Patrick Blackett to help  them, and with Mr A. P. 
   !         !     
 however. andtheteisattenua­ tionduetotheleakingofenergyfromtheuppersurfaceoftheductaswellasbyscattering and absorption. Energyisalsoscattered outoftheductbecause ofaroughseasurface.76Ilhas heenfoundexperimentallyJ7 thatS-hand radiation (10emwavelength) isonlypartially trapped bytheevaporation duct.withattenuation ratesavcraging ahoutO.H5dB/nmi.Gen­ erally,thereislessattenuation at,Sbandthehighertheradarantenna orthetarget altitude.36.J7AtXhand(Jcmwavelength). 
 The receiver output characteristic with signal so only is  represented by the solid curve. The effect of noise is shown by the dashed curve. Noise  displaces the zero crossing by an amount At. 
 END CHARACTERISTICS IN THREE WAYS .OISE INTRODUCED BY THE FRONT END INCREASES THE RADAR NOISE TEMPERATURE  DEGRADING SENSITIVITY  AND LIMITS THE  MAXIMUM RANGE AT WHICH TARGETS ARE DETECTABLE &RONT 
 Inanairborne set,there isafurther complication due tothefact that theradial velocity depends onthe depression angle, which means that thedoppler frequency ofthe ground clutter varies with the range. In consequence, the phase-shift unit cannot beused for clutter atlarge LV.A.Olson, “AMoving Coho Conversion Unit, ”RL Report No. 975, Apr. 
 PLAYED ON THE 3!2 MAP AS MOVING TARGET SYMBOLS 4HE SYMBOLS ARE ACCURATELY LOCATED AT THEIR TRUE AZIMUTH POSITION RELATIVE TO THE MAP CENTER4HE ;3!2= MAP ON WHICH THE MOVING TARGET SYMBOL IS DISPLAYED IS COLLECTED AND PROCESSED SIMUL 
 BASE  WHICH CONTAINS THE RANGE OF CHARACTERISTIC PARAMETERS FREQUENCY  PULSE WIDTH  02)   THE RELATED PATTERN OF AGILITY RANDOM  STAGGER  ETC  FO R EACH EMITTER  THE TYPE OF  ANTENNA SCANNING PATTERN AND PERIODS PERMITS THE GENERATION OF AN EMITTER LIST WITH AN IDENTIFICATION SCORE 4HE %3- RECEIVER IS USED TO CONTROL THE DEPLOYMENT AND OPERATION OF %#- THE LINK BETWEEN %3- AND %#- IS OFTEN AUTOMATIC ! SINGLE RECEIVED RADAR PULSE IS CHARACTERIZED BY A NUMBER OF MEASURABLE PARAME 
 23.2  23.3 Design Considerations  ...........................................  23.5  Attenuation Effe cts  ............................................  23.5  Range and Velocity Ambiguities  ......................... 
 MARIZED AS FOLLOWS &OR VERTICAL POLARIZATION  THE MAJOR ENERGY OF THE (& CLUTTER SIGNAL APPEARS IN SPECTRAL LINES DISPLACED TO EITHER SIDE OF THE CARRIER FREQUENCY BY THE FREQUENCY OF SEA WAVES HAVING  A WAVELENGTH EQUAL TO HALF THE (& WAVELENGTH K   IN METERS  4HE RELATIVE STRENGTHS OF THE PLUS AND MINUS LINES ARE DETERMINED BY THE PROPORTION OF ADVANCING AND RECEDING "RAGG 
 B., and G. T. Poulton: High-Efftciency Microwave Reflector Antennas-A Review,  I'roc. 
 MEDIUM 02&  WAVEFORM THAT HAS ACCEPTABLE PERFORMANCE FOR TARGETS THAT ARE COMPETING WITH SIDELOBE CLUTTER  OR THE COMBINATION OF &ORWARD 
  D"7(Z THUS  #DP    D" #OMBINATIONS OF EARTH MASKING  ANTENNA SHIELDING  SPATIAL CANCELLATION  AND SPEC 
 126. Ilastings. K. 
 MOVING SHIPS  SO THE REVISIT INTERVAL COULD BE TENS  2ADAR n. n. n. 
 An especially common multiple-beam design is the monopulse antenna of Fig. 6.3e, used for angle determination on a single pulse, as the name implies. In this instance the second beam is normally a difference beam with its null at the peak of the first beam. 
 Switching times are measiired in hundreds of  n~icroseconds rather than a few microseconds as is common with other microwave phase  shifters. The long time is due to the large inductance of the solenoid and by th%v fact that the  waveguide around which the solenoid is wrapped acts as a shorted turn. The resulting eddy  currents generated by the shorted turn limit the speed with which the magnetic field can be  changed. 
 48. D. K. 
 Readers interested in the details of these analog processing tech - niques will find details in the first and second editions of this handbook.1,2 All but the simplest of radars require more than one receiver channel. Figure 6.1  shows a single receiver channel that may be replicated any number of times depending  on the radar system requirements. Monopulse radars typically include three receiver  channels, sum, delta azimuth, and delta elevation channels, used to provide improved  angle accuracy. 
 A con­ version from time domain to frequency domain process­ ing at an early point in the signal flow, along with digital  frequency analysis, results in a system that is inherently  free from drift.  The precision of the height measurement is also of  interest. Ground test data have established that the al­ timeter noise level approaches 2 centimeter s at low wave  height for I-second averaging. 
 The quartz issupported directly bythe steel electrode. The occluded airfilm provides thenecessary acoustic mismatch. DesignConstants forMercury Lines.—The delay time ispresumed tobe given. 
 S. E., W. Fishbein, and 0. 
 PATTERN SLOPE IS DETERMINED BY THE DERIVATIVE OF THE SCAN PATTERN  WHICH DIFFERS FROM THE $0#! CRITERION 4HIS TECHNIQUE IS KNOWN AS  STEP 
 Geosci. Remote Sens. Symp. 
 The advantages of nuclear prime power sys- tems include (1) reduced mass and size at the higher power levels; (2) no per- turbation by natural background in low earth orbit (LEO) and geosynchronous orbit (GEO); (3) no need for alignment, gimballing, slip rings, and long-life batteries, suggesting that the nuclear system will have significantly enhanced reliability; (4) reduced effect on SBR antenna, i.e., multipath and sidelobes; (5) nuclear-hard compared with solar systems; (6) reduced optical and radar signature; (7) reduced cost by a factor of 3; (8) continuous availability of power; (9) no orientation requirements; (10) no maneuver limitations; (11) no power degradation, i.e., beginning-of-life-end-of-life (BOL-EOL) power level; and (12) no large, flexible structure. The issue of safety was addressed in 1980 by the United Nations Working Group report,59 which studied the safety of nuclear power sources (NPS) in space. That group reaffirmed the conclusion that NPS can be used safely in space. 
 First, the InSAR results were compared to measurements from levelling benchmarks for a quality check. Then, the mean displacement maps and time series were analysed for studying the subsidence characteristics in space and time. Thanks to the availability of data covering the whole urban area with unprecedented spatial and temporal density, it was possible to provide a reliable assessment of subsidence causes. 
 References [1] The Second World War 1939 –1945 —Royal Air Force, Signals Volume VI —Radar in Maritime Warfare, Air Ministry, 1954 (TNA AIR 10/5555) [2] Trial No. 194. Comparison of Production A.S.V. 
 (Submitted as  Ohio State University Dissertation), U.S. Gov. Printing Office: 1974-657-017/347. 
 Eastwood. Before the War Dr W. S. 
 Compared to the medium PRF plot shown in Figure 5.16, the  clear region (and corresponding losses) is dramatically better. Unfortunately, range  is very ambiguous. Normally, a RGHPRF range-while-search (RWS) mode is inter - leaved with the highest performance velocity-search (VS) mode to range on previ - ously detected targets. 
 Sinusoidal modulations can have a significant impact on radar  performance, though the degree to which they cause degradation often depends on  their relationship to the radar PRF and their magnitude relative to the random modu- lations. Examples of such undesired sinusoidal modulations are in-band, unfilterable  mixer products, or leakage due to insufficient isolation between signal sources within  a receiver or exciter. In addition to external sources of interference, the radar designer FIGURE 6.6  Clutter residue due to LO phase noiseH(f)Phase Noise after  Downconv ersion Frequency100 Hz 1 kHz 10 kHz 100 kHz 1 MHzCombined Doppler Filter  and Receiv er Filter  Response Clutter ResidueNoise Level (dBc/Hz)0 −10 −20 −30 −40 −5010 Filter Response (dB)−120 −130 −140 −150 −160 −170−110L’(f) ch06.indd   18 12/17/07   2:03:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Rainaddstotheabsorption andeliminates theregionsofrelatively lowattenu­ ation.Forexample, arainofabollt5mm/hincreases theattenuation ofthe94-GHz window byalmostanorderofmagnitude. Figure14.15showsthatarainof0.25mm/hwouldnot significantly increase theclear-air attenuation. (Atmicrowave frequencies thebackscatter from rainhasfargreatereffectonradarperformance thantheattenuation. 
 Therefore the interfer­ ence would be in the receiver for a much longer time and at a higher energy level than when  limited before narrowbanding. Desired signals which appear simultaneously with the noise  spike might not be detected, but the circuit does not allow the noise to influence the receiver  for a time longer than the duration of a noise spike. This device depends on the use of a limiter. 
 Frequency and polarization diversity can provide an improved signal-to-noise ratio by con-  verting a Swerling type 1 target (Sec. 2.8) with scan-to-scan fluctuations to a Swerling type 2  with pulse-to-pulse fluctuation. From 4 to 7 dB improvement in signal-to-noise ratio might be  achieved in the diplex mode as compared with the simplex mode.46  The ARSR-3 utilizes a klystron amplifier to achieve 5 MW peak power and 3.6 kW  average power. 
 In Proceedings of the IEEE International Geoscience & Remote Sensing Symposium, Anchorage, AK, USA, 20–24 September 2004. 5. Liu, A.K.; Peng, C.Y.; Schumacher, J.D. 
 Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 14.4  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 in Figure 14.1. Similar interactions occur for ship targets when bulkheads, railings,  masts, and other topside features become mirrored in the mean sea surface. 
 Donnelley (ed.), National Oceanic and Atmospheric  Administration, 1980. ch20.indd   77 12/20/07   1:17:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The STC action should be in the RF portion of the receiver rather than in the  logarithmic amplifier. 508 INTRODUCTION TO RADAR SYSTEMS  13.9 ANGEL ECHOES  Radar echoes can be obtained from regions of the atmosphere where no apparent rdkcting  sources seem to exist. These have been called by various names, but they are commonly called  olwsts or angels. 
 TO 
 117–138, February 1987;  pt. II, pp. 167–174, March 1987. 
 LOOP  IMPLEMENTATION TECHNIQUES  28 RECEIVER     
 MENTS AND TEST PROCEDURES DEFINED WITHIN )%#   4HIS IS A COMPREHENSIVE SET OF  REQUIREMENTS THAT ARE APPLICABLE TO ALL SHIPS NAVIGATIONAL AND RADIO COMMUNICATIONS EQUIPMENT 4HEY COVER SUCH ASPECTS AS TEMPERATURE  SHOCK  VIBRATION  CORROSION  AND RESISTANCE TO WATER AND OIL INGRESS $ETAILED REQUIREMENTS ON ELECTROMAGNETIC EMIS 
 The system operates in a synthetic aperture radar (SAR) mapping  mode as well as in a three-port azimuth interferometer ground moving target  indication (GMTI) target detection and tracking mode. Use of the three-port  aperture on receive enables a clutter suppression interferometry technique that  allows the operator to detect, accurately locate, and track slow moving ground  targets in the presence of competing ground clutter . Raytheon Company Phased Array Radars. 
 FILM  METAL DEPOSITION TECHNIQUES TO DELINEATE THE VERY FINE FEATURES THAT MAKE UP THE MICRO 
 This shaping of the sum-signal E field is accomplished independently of the  difference-signal E field. The difference signal is two TE10-mode signals, side by side,  arriving at the septum of Figure 9.6 out of phase. At the septum, it becomes the TE20  mode, which propagates to the horn aperture and uses the full width of the horn as  desired. 
 The fundamental geometrical quantities involved inradar displays are the spherical coordinates ofthe target measured from the origin atthe radar antenna: range, azimuth angle (orbearing), and elevation angle. Practical] yevery radar display uses one ortwo ofthese quanti- ties directly ascoordinates onthe tube face, orisasimple modification ofadisplay which does. The vast majority ofdisplays use asone coordinate the value of slant range, itshorizontal projection (ground range), oritsvertical projection (altitude). 
 T. P. Leonard and S. 
 5.1 ). This  is called lohe switching, sequemial switching, or sequential lobing. Figure 5.la is a polar rep­ resentation of the antenna beam (minus the sidelobes) in the two switched positions. 
 1966.  17. Bean. 
 WAVE SLOW 
 Mostcommercial aircraft haveacrosssectiongreaterIhanthe2 m2 specifled forthisradar.Thislowvalueisnecessary, however. ifsmallgeneral-aviation aircraft arealsotohedetected. The5rpmrotation rateoftheantenna corresponds toa12-second interval between targetobservations (scantime).Thisisaboutthelongestinterval thatcanusuallybetolerated hetween observations ofaircraft targets.Ahighrotation rateisneededforgoodtargettrack­ ing.Alowrotation rateisdesiredformorehitsontarget,whichreducestherequirements for largetransmitter powerorantenna aperture. 
 PHASE  WAVEFRONT AT THE ANTENNA FACE  THEN LARGE GRATING LOBES WOULD BE GENERATED IN THE FAR 
 TO 
 The Mixer Crystal.-Since nosatisfactory amplifier formicro- waves exists, theconversion tointermediate frequency must bemade at — “m=.1 a.Pinend a.Sylvania b,WesternElectric FIG. 11.19.—Microwave mixer crystals. the low level ofreceived signal powers. 
 DETECTION OF RADAR SIGNALS IN NOISE 375  the values of Br which maximize the signal-to-noise ratio,(SNR) for.various combinations of  filters and pulse shapes. It can be seen that the loss in SNR incurred by use of these non­ matched filters is small.  Matched filter with nonwhite noise. 
 VARYING SLOPE INPUT TO THE FREQUENCY REGISTER 4HE FREQUENCY ACCUMULATOR MAY BE CLOCKED EITHER AT THE SAME RATE AS THE PHASE ACCUMULATOR OR AT A SUB 
 6ILLE ANALYSIS OF (& RADAR MEASUREMENTS OF AN ACCELERAT 
 Conclusions In this paper, a time-series deformation model considering rheological parameters was proposed, and the rheological parameters of elastic modulus and viscosity were introduced into a traditional empirical functional model. Based on the functional relationship between strain and time in the Kelvin rheological model, the function between LOS deformation and rheological parameters was established and the original linear deformation model was improved. The genetic algorithm method was used to solve for the initial values of the model parameters, and the simplex method was used for subsequent optimization. 
 167. J. J. 
 (25.7). Additional errors occur when the di- rect range sum estimation method is used. They include interference from the direct-path signal (analogous to eclipsing), pulse instability, and multipath ef- fects. 
 One is the optical, or itrtet;fkrerrce, region, which is within the line of sight  (direct observation) of tlie radar. The other is the difrractiort region, which lies beyond the line  of siglit, or beyond tlie horizon, of the radar. Radar energy found in this region is usually due  to diffraction by the curvature of the earth or refraction by the earth's atmosphere. 
 WIDTH AT HIGH POWER AND BEING AN AMPLIFIER  IT CAN WORK WELL WITH THE FREQUENCY AND PHASE MODULATED WAVEFORMS NEEDED FOR PULSE COMPRESSION +LYSTRONS HAVE OPER 
   PP n  -ARCH   7 $ "URNSIDE  # 7 0ISTORIUS  AND - # 'ILREATH  h! DUAL CHAMBER 'REGORIAN SUBREFLECTOR  FOR COMPACT RANGE APPLICATIONS v  0ROC OF THE !NTENNA -EASUREMENT 4ECHNIQUES !SSOCIATION    3EPTEMBER n/CTOBER     PP n. £{°{È  2!$!2 (!.$"//+   % & +NOTT   2ADAR #ROSS 3ECTION -EASUREMENTS  .EW 9ORK 6AN .OSTRAND 2EINHOLD     PP n  $ , -ENSA  (IGH 2ESOLUTION 2ADAR )MAGING  .ORWOOD  -! !RTECH (OUSE    7 7 3ALISBURY  h!BSORBENT "ODY FOR %LECTROMAGNETIC 7AVES v 53 0ATENT       *UNE     7 % "LORE  h4HE RADAR CROSS SECTION OF OGIVES  DOUBLE 
 National Weather Service employ the des- ignation WSR, which is not associated with the JETDS nomenclature. The num- ber following the designation indicates the year in which the radar was put into service. When a letter follows the number, it indicates the letter-band designa- tion. 
 These fluctuations are largely from rapid changes in target reflectivity, a(f), that is, from target amplitude scin- tillation. The random modulation of \e\ causes an additional angle noise compo- nent that affects the choice of AGC bandwidth. At very low signal-to-noise ratios (SNR < 4 dB) the AGC voltage is limited to a minimum value by the noise level. 
 The algorithm is able to improve the azimuth suppression while preserving the mail lobe resolution. The work in [ 4] considers the problem of Doppler parameter estimation and compensation for SAR data acquired by airborne systems with very high squint geometries. The authors propose an algorithm based on extended multiple aperture mapdrift, which is able to estimate the Doppler phase spatial variation of the third-order. 
 R. Rosenzweig: Learn the Language of Mixer Specification, Microwa~~es, vol.  17, pp. 
 C.: Characteristics of Radar Sea Clutter, pt !-Persistent Target-Like Echoes in Sea  Clutter, Naval Research Laboratory Report 4902, Washington, D.C., Mar. 19, 1957.  8. 
 The foregoing assumes that the rate of travel of the electron beam is constant, which is theusual case in the design of indicators for navigational radar. If the antenna is trained on a target at 10 miles while using the 20-mile range scale, the time for the 20-mile round trip of the transmitted pulse andthe returning echo is 123.5 microseconds. At 123.5 microseconds, followingthe instant of triggering the transmitter and sending the timing trigger pulseto the indicator to deﬂect the electron beam radially, the electron beam willhave moved a distance of 10 miles in its sweep or on the time base. 
 IIo HOW RADAR WORKS  light, being, in fact, two or three echo spots on two or  three traces in succession. As the transparent map is  superimposed over the tube end these spots give a ready  indication.  Obviously the construction of a CRT for PPI display  must be different from that for Type A, for example. 
 This process forms a matched filter to  the entire pulse train.2,3 MTI and pulse doppler radars share the following characteristics: ● Coherent transmission and reception; that is, each transmitted pulse and the receiver  local oscillator are synchronized to a free-running, highly stable oscillator . ● Coherent processing to reject main-beam clutter, enhance target detection, and aid  in target discrimination or classification. MTI radars can also be implemented using a doppler filter bank, blurring the historic  delineation between MTI and pulse doppler radars. 
 Also it can aid in the requesting of height-finder data by the operator, blanking of areas  coritaining excessive interference or weather, providing training of operators by superimposing  sinlulated targets, and otller futictions necessary for an air-traffic-control system or air-defense  system. The operator can conirnunicate in an interactive manner with the computer by such  means as a keyboard, light pen, track ball, or even voice entry. Sometimes an auxiliary  CRT display is mounted adjacent to the main radar display to provide tabular data and  other information that would otherwise clutter the main display. 
 The measurement of angle is similar to that of an  amplitude-cornparis011 monopi~lsc trackitig radar except that it is made open loop; i.e., the  output voltage from tlie angle-error detector is calibrated to read elevation angle. Two  displaced horns with combining circuitry, or a single multimode horn. is the principle  modification reqiiircd of tllc anteniia. 
 Curve l represents the locus of the geometrical line of sight  as defined by Eq. (12.14) fork= t, Curv~ 2 is the constant signal contour in the diffraction  region for a signal strength equal to the free-space signal that would be received from a range  of approximately 220 nautical miles; that is, if the radar is to detect a target that lies along this  contour, it must be capable or detecting the same target in free space at a range of 220 nautical  miles. If the target were at an altitude or 200 ft, the maxinn,m detection range would be  reduced from 220 to about 35 nautical ·miles. 
 M.: A Method of Calculating the Field over a Plane Aperture Required to Produce a  Given Polar Diagram, J. IEE. vol. 
 Mikhaylyukov, and I. P. Malyavin, “Exterior noise  adaptive rejection for OTH radar implementations,” IEEE Int. 
 SECTION ESTIMATION v  0ROC )%%%   VOL   PP n  !UGUST   ) * 'UPTA AND 7 $ "URNSIDE  h0HYSICAL OPTICS CORRECTION FOR BACKSCATTERING FROM CURVED   SURFACES v )%%% 4RANS  VOL !0 
 17.11  Main-Beam Clutter  .............................................  17.16  Main-Beam Clutter Filtering  ...............................  17.16  Altitude-Line Clutter Filtering  .............................. 
 Another very useful tool for the computation of the impedance variation with scanning is the grating-lobe series,65'66 which describes the impedance variation of an infinite array of regularly spaced elements. Nonisolating Feeds. When nonisolating feeds are used, the mutual-coupling effects become dependent on whether the phase-shifting element is reciprocal or nonreciprocal. 
 (/2):/. 2!$!2   Óä°£Ç 4HE TRACES PLOT THE VIRTUAL HEIGHT VERSUS RADIOWAVE FREQUENCY FOR THE  ORDINARY RAY SEE  SUBSECTION BELOW ON RADIOWAVE PROPAGATION  3OUNDINGS OF THIS TYPEIONOGRAMS MEASURE THE RETURN TRIP TIME DELAY FOR A SIGNAL TO TRAVEL UP TO THE HEIGHT AT WHICH THE ELECTRON DENSITY IS SUFFICIENT TO REFLECT IT  THAT IS  WHERE THE PLASMA FREQUENCY  F P EQUALS  THE INCIDENT RADIOWAVE FREQUENCY !LSO SHOWN IN &IGURE  IS THE CORRESPONDING MONTHLY MEDIAN  TAKEN FROM THE  MODEL OF 4HOMASON ET AL #ONSIDER THE CRITICAL FREQUENCY  THAT IS  THE HIGHEST REFLECTED  FREQUENCY  CORRESPONDING TO THE IONOSPHERES PEAK ELECTRON DENSITY 4HE UPPER AND LOWER DECILES DEPART FROM THE MEDIAN BY TYPICALLY  o  /VER SUCH A RANGE OF FRE 
 (2o) becomes 1/2.2 or–7db,whereas Table 16.2 shows that thefluctuation due tointernal motion ofthecloud isonly –17db. From theMTI point of. ISEC.16.9] TARGET VISIBIL1 TY 651 view translational motion ismore serious than theinternal motion ofthe cloud. 
 10, 1975.  67. Bahr, A. 
 17.6 Video signals I a Basic trigger Tomodulator Waveforms Basic trigger A B c D E F G H zInterrupted sinusoid Phas~hifted sinusoid Phaseshifted pulses Delayed trigger Switching voltage Selected pulsetrain Modulator trigger Codedpulses Basictrigger (contracted timescale)I I I L Ill IllIllIllIII[11IllIll J‘deo‘witch‘aveform~ IfOutputsignals 111111~ Pulses Videosignal Fm.17+3a —Phase-shifted pulses transmitting station.. SEC.17.6] THEPHASE-SHIF.T METHOD 699 Video Trigger { t FromSwitch(b’)Switch .M’Flip-flop receiverand decoder(d) (d) I’t f Flip-flop, Delay E ,- : “-1-‘b’) =Flip-flop (a) A’ I F’ I Switch— Comparison (c)Amplifiercircuit . 4 # ,~G’, I I kSwitched Switch D’ Pulse c’ Phase. 
 The specific region on the earth's surface illuminated by an HF radar depends on iono-  spheric conditions. A "typical" patch of the ground illuminated by a single freqtiency might be  about 1000 km in the range coordinate. The region from 1000 to 4000 km might therefore  require the radiation of three different frequencies for full coverage. 
 and A. H. LaGrone: Radar Reflections from Insects in tlie Lower  Atmosphere. 
 TO 
 [4] Brandon, P.S., "The design of a nonlinear pulse compression system to give a low loss high resolution Radar performance", Marconi Review , vol.36, pp.1- 45, 1973.  l5] Fowle, E.N., "The Design of FM Pulse Compression Signals", IEEE Trans. on  Information Theory, vol. 
 The references included in the first edition  represented a large fraction of those available at the time. It would have heen difficult to add to  them extensively or to include many additional topics. This is not so with the second edition. 
 COMPLIANT SYSTEM TO THE #-2 MARKET )T HAS A PEAK OUTPUT POWER OF  7 AND A DUTY CYCLE OF  &IGURE  SHOWS A PHOTOGRAPH OF THE TRANSMITTER ELECTRONICS )N ORDER TO OBTAIN THE REQUIRED SHORT 
 The heavy commercial oils used in their experiment  were effective in suppressing small-scale waves over a range of wind speeds well  beyond those which would normally disperse the lighter natural oils, so the effect of oil  spills on sea clutter should be expected to extend to the higher wind speeds. In fact, at  these higher wind speeds, the depression of radar backscatter by such oils at X and Ka  bands can reach 10 to 20 dB at intermediate grazing angles between 30° and 60°.86,87 15.4 THEORIES AND MODELS OF SEA CLUTTER In addition to providing an intellectual basis for “understanding” sea clutter phenom - ena, a complete theory of sea clutter should ideally provide accurate a priori  predic - tions of all aspects of clutter behavior under all possible environmental conditions. In  spite of over 60 years of effort, the theory of sea clutter does neither of these tasks very  well, as we will see in this section. 
 Indeed, reflection hasbeen observed onunusually flat terrain, such asan airfield, atmicrowave frequencies. Except insuch unusual circumstances there isvery little evidence ofground reflection atwavelengths of10cm orless. For microwaves, then, the results ofthis section are almost wholly restricted totransmission over water atnearly grazing incidence. 
 Errors of ± 1 jxs have been measured when a direct LOS is available.131 They increase to ±5 JJLS over a tropospheric propagation path.130 Since two clocks are used in indirect time synchronization, clock stability is, to a first order, AT/2JM. For T14 on the order of hours, atomic clocks are usually required to satisfy this requirement. Temperature-controlled crystal oscillators, an integral part of atomic clocks, will usually satisfy short-term (< 1 s) stability requirements. 
 Harmonics: Both linear-beam tubes and CFAs produce harmonic power output of typically -25 dB (with respect to fundamental power output) at the sec-Voltage Gain Bandwidth X-rays Efficiency Basic With depressed collectors Ion pump Weight Size Cost Spurious noised Spurious modes (typical) Usable dynamic range Control electrode Magnetic field Dynamic/static impedance Phase-modulation sensitivityLinear-beam tubes Klystron TWT High voltage (1 MW requires approx. 90 kV) 30-70 dB l-8%t 10-15% Severe, but lead is reliable 15-30% 40-60% Required on large tubes Higher Larger Medium High -9OdB None TT mode during rise and fall if cathode-pulsed; none if mod- anode- or grid- pulsed 40-80 dB None, or mod-anode, or grid PPM up to 1 MW at S band; sole- noid otherwise; barrel magnet rare (SLAC); none for ESFK 0.8 5-40° per 1% &E/ECrossed-field tubes* Conventional High-gain Low voltage (1 MW requires approx. 40 kV) 8-15 dB 15-30 dB 10-15% Not usually a problem 35-45% N.A. 
 IEE. pt C ,ol. 104. 
 BASED 7INDOWS OPERATING SYSTEMS     .4   80  AS WELL AS  ,).58 !LTHOUGH THE '2!30 CODE IS 0/ 
 Itisclearly anintegration process operating ataloss rather than atagain,incontrast tothe sweep-to-sweep integration discussed earlier, foritincludes with the signal anunnecessarily large amount ofnoise. The result isanincrease insignal power required for detection: forb<<l/T, S~,. isroughly proportional tol/v’~. 
 Typically, the antenna will visit every beam position once  during a search frame. Basic Configuration.  Figure 4.8 shows a representative configuration of a pulse  doppler radar utilizing digital signal processing under the control of a mission processor. 
 ING THE LATE S TO REPLACE THE EARLIER PRIMARY AND SECONDARY SURVEILLANCE RADARS USED FOR AIR TRAFFIC CONTROL BY #ANADAS -INISTRY OF 4RANSPORT   4HE PRIMARY SURVEILLANCE  RADAR CONSISTS OF A ROTATING REFLECTOR  HORN 
 J. Pirttil ä and M. Lehtinen, “Solving the range-doppler dilemma with the SMPRF pulse code,” in  30th Conf. 
 Quart.J.Ro.v.Melt'or.Soc.,vol.Hg,pp. 485-495, 1962. 70.Baltan,L.J.:..RadarObservation oftheAtmosphere," Vnil'.ofCilicago Press,Chicago. 
 Some parameters of the radar equation are deter - mined by what the radar is required to do. Others may be decided upon unilaterally by  the customer—but that should be done with caution. The customer usually should be  the one who states the nature of the radar target, the environment in which the radar  is to operate, restrictions on size and weight, the use to which the radar information  is to be put, and any other constraints that have to be imposed. 
 This also  reduce s interference between transmitters in close proximit y.  Digital Modulation   With the advancements of software defined radio and digital  signal processing applied to radar, mo re complex pulse  modulations are now used. For example, more effective anti - spoofing can be accomplished using M -ary PSK or QAM  modulati ons. 
 The radiation pattern of an array may be shaped by modifying  the aperture distribution. Good pattern approximations can be obtained by using phase  only. In particular, the beam may be broadened by applying a spherical phase distribu - tion to the aperture or by approximating it with a gable (triangular) phase distribution. 
 Also, there are component developments at millimeter  wavelengths which indicate that technology is not basically limited. For example, high power  has been demonstrated with the gyrotron, or electron cyclotron maser, comparable to that  achieved with microwave devices. Kilowatts of CW power can be obtained in the vicinity of  I-mm wavelength and several tens or kilowatts at 3-mm wavelength. 
 (FKR E (FKRnE ' )RFXVLQJ' )RFXVLQJ' )RFXVLQJ ,PDJH 5HJLVWUDWLRQ(FKRNE (OHYDWLRQ3URFHVVLQJ ,QFRKHUHQW $GGLWLRQ ',PDJHZLWK/RZ $]LPXWK6LGHOREHV   Figure 2. Flowchart of the proposed processing method for azimuth sidelobes suppression. The data acquired on each pass were ﬁrst focused to obtain a 2D image. 
 Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar.  GROUND PENETRATING RADAR  21.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 Element antennas are characterized by linear polarization, low directivity, and rela - tively limited bandwidth, unless either end-loading or distributed-loading techniques  are employed in which case bandwidth is increased at the expense of radiation effi - ciency. An elemental antenna is a dipole in contrast to aperture antennas such as horns. 
 POLAR 
 The gain of a klystron can be  typically 15 to 20 dB per stage when synchronously tuned, so that a four-cavity (three-stage)  klystron ca_n provide over 50 dB of gain.  After the bunched electron beam delivers its RF power to the output cavity, the electrons  are removed by the collector electrode which is at, or slightly below, the potential of the  interaction structure. From 50 to 80 percent of the d-c input power might be converted to heat  in typical linear-beam tubes, and most of this heat appears at the collector. 
 $ELAY .ETWORKS  &IGURE A SHOWS A TIME 
 GROUND INTERFACE IS ASSUMED TO BE PERFECTLY FLAT &ROM THE FIELD PLOT  ONE CAN RECOGNIZE THE ANTENNA STRUCTURE AND THE STRONG FIELD  REGION ON AND INSIDE THE HORN PLATE 4HE BURIED OBJECT IS ALSO VISIBLE 4HE MAIN REFLEC 
 the  signal-to-noise ratio will be within 0.5 dB of optimum form ranging over a value of 0.44 11 for a  nonfluctuating target or a Swerling case l, and 0.34 n for a Swerling case 2.59  The quantization or signals into but two levels (zero or one} in the binary moving-window  detector results in a loss of about 1.5 to 2 dB in signal-to-noise ratio as compared to the ideal  post-detection integrator.53 55•5 7 When the amplitude is quantized into more than two levels,  !he loss is less. For example, quantization into four levels (2 bits), reduces the loss to about  onc-t hird t ha! ex pcricnccd in two-level, or binary. quantization ( t bit). 
 § ©¨¶ ¸·  ;= #ONSTANT  MANEUVERA UNITS OF GS ,AG BIAS  IN FILTERED TRACK STATE A4 
 84 The normalization of the  threshold is accomplished in thc•l!OG/CFAR by subtraction rather than by division as in the  conventional cell-averaging CFAR! Also, the LOG/CF AR is capable of operating over a larger  dynamic range of background noise levels, but it has poorer detectability for ·the same number  of reference noise samples than the conventional cell-averaging CF AR. DETECTION OF RADAR SIGNALS IN NOISI\ 395  CF AR is widely used to prevent clutter and noise interference from saturating the display  of an ordinary radar and preventing targets from-being obscured. It is also needed in ADT, or  track-while-scan systems, to prevent the tracking computer from being overloaded by extra­ neous clutter targets or noise. 
 When search  must be interrupted for a higher-priority task, the computer program must be d.esigned to do  so with minimum disruption. In scheduling the various radar functions, the computer must  insure that the average-power limits of the radar transmitter are not exceeded.  The llexibility of a phased-array radar allows more freedom in the selection of a detection  criterion. 
 With newer devices acoustic delay lines (surface and material waves) are used.  It is  important that the filter is adapted to the frequency pass (i.e. matched filters). 
 8  'ERMANY       8 6ARIOUS2!$!23!4 
 Thebistatic radarisnotanewconcept. Itsprinciple wasknown and demonstrated manyyearsbeforethedevelopment ofpractical monostatic radar.InSec.1.5it wasmentioned thatthefirst"radar"observations inboththeUnitedStatesandinGreat Britainweremadewithseparated CWtransmitters andreceivers. Theseearlyradarswere knownaswave-interference equipments butwerethesameaswhatwouldnowbecalled bistaticradar.TaylorandYoungoftheNavalResearch Laboratory firstdemonstrated bistatic radarforthedetection ofshipsin1922.Theirworkwasdisclosed inapatentissuedin1934.59 Theearlyexperiments withwave-interference (bistatic) radarledtothedevelopment ofmono­ staticradarinthelate1930sinboththiscountry andabroad. 
 VIIIA, ﬁrst entering service in June 1944. ASV Mk. VIIIA had a peak power of about 40 kW, with pulse lengths of 0.5, 1 or 2 μs and corresponding PRFs of 1400, 700 or 360 c/s, according to the selected range scale [ 3]. 
 HORIZON RADAR v  )%%% 4RANS  !%3  VOL   PP n  *ANUARY   , ! "ERRY AND - % #HRISMAN  h! &/242!. PROGRAM FOR CALCULATION OF GROUND WAVE  PROPAGATION OVER HOMOGENEOUS SPHERICAL EARTH FOR DIPOLE ANTENNAS v .AT "UR 3TAND 2EPT       3 2OTHERAM  h'ROUND WAVE PROPAGATION  PARTS  AND  v  )%% 0ROC  0T &   VOL     PP n    3 * !NDERSON  0 * %DWARDS  0 -ARRONE  AND 9 ) !BRAMOVICH  h)NVESTIGATIONS WITH 3%#!2 ! BISTATIC (& SURFACE WAVE RADAR v  0ROC )%%% )NT #ONF ON 2ADAR  2!$!2    !DELAIDE   3EPTEMBER   $ % "ARRICK  h4HEORY OF (& AND 6(& PROPAGATION ACROSS THE ROUGH SEA  PTS ) AND  v  2ADIO  3CIENCE  VOL   PP n  -AY   , 3EVGI   #OMPLEX  %LECTROMAGNETIC  0ROBLEMS  AND  .UMERICAL  3IMULATION  !PPROACHES   (OBOKEN  .* )%%% 0RESS    3 * !NDERSON   * 0RASCHIFKA  AND ) - &UKS  h-ULTIPLE SCATTERING OF (& RADIOWAVES PROPAGAT 
 In princi-  ple, the CW radar may be converted into a pulse radar as shown in Fig. 4.Ih by providing a  power amplifier and a modulator to turn the amplifier on and off for tllc purpose ofgenerating  pulses. The chief difference between the pulse radar of Fig. 
 LOOK  DWELL  WHERE  M IS TYPICALLY  4HE 02& IS HIGH ENOUGH FOR AT MOST ONLY A DOPPLER SIGN  AMBIGUITY $ETECTIONS IN LOOKS  THROUGH  M  MUST CORRELATE IN  DOPPLER WITH DETECTIONS  IN THE FIRST LOOK  WHICH HAS NO SLOPE ! DOPPLER CORRELATION WINDOW IS SET EQUAL TO THE MAXIMUM DOPPLER OFFSET DUE TO LINEAR 
 Vibrating Targets in a SAR Image.  Consider a SAR observing a scene that con - tains a point target whose position is oscillating sinusoidally (vibrating) (see Section 9.4  of Carrara et al.3). The component of the vibration amplitude that is parallel to the line- of-sight (LOS) is d. 
 TION LOSS OF THE DEVICE 4HE TRADEOFF BETWEEN SHORT GATE LENGTH THUS LOWER PROCESSING YIELD  AND INSERTION LOSS MUST BE EXAMINED   4HE VALUE OF THE PARASITIC DRAIN 
 Another, similar SAR image quality metric (IQM) is the contrast ratio (CR) ,  defined as the ratio of the average intensity of a typical bright region in a SAR image  to the intensity of an NRA. If thermal noise is negligible, then CR = 1/MNR. Comparison of SAR Imagery and Optical Imagery. 
 TIME IE  RANGE CELL  PROCESSING   4HE EXPECTED NUMBER OF SPATIAL DOF IS NOT HIGHER WE HAVE ONLY TO ADD THE DOF IN TIME 4HE ADAPTIVE BEAMFORMING ALGORITHMS HAVE TO BE IMPLEMENTED INTO THE 3!2 PROCESSING WHICH IS ALWAYS SPACE 
 6.10. PPI Radar for Search, Control, and Pilotage.’-In the last section, animportant historical development has been traced. The first radar setsused fixed antennas and floodlighting technique, and required that amanipulation beperformed tofind the azimuth ofeach target. 
   6OL   .ORWOOD  -! !RTECH (OUSE  )NC    PP n  - " 2INGEL  h!N ADVANCED COMPUTER CALCULATION OF GROUND CLUTTER IN AN AIRBORNE PULSE DOPPLER  RADAR v IN  .!%#/.  2ECORD   PP n AND REPRINTED IN $ + "ARTON   #7 AND $OPPLER  2ADARS  3ECTION 6) 
 22. J. Thomason, G. 
 Spurious Distortion of Radiated Spectrum. It is a surprise to many radar engineers that components of the radar receiver can cause degradation of the radiated transmitter spectrum, generating harmonics of the carrier frequency or spurious doppler spectra, both of which are often required to be 50 dB or more below the carrier. Harmonics can create interference in other electronic equipment, and their maximum levels are specified by the National Telecommunications and Information Administration (NTIA) and MIL- STD-469. 
 Moreover, the associate apparatus neces~  sary for CRT display takes up space in the cockpit.  In present popular electrical altimeter systems the  transmission is not of pulses, but of continuous waves.  They are emitted with rhythmic variations in frequency  from the underside of the aircraft. 
 2.31  2.6 Pattern Propagati on Factor  ....................................  2.31  General Discussi on  ............................................  2.32  Mathematical Definition  ...................................... 
 A rapidly tuning laser  local oscihator or a large bank of IF filters are necessary to compensate for the farge doppler  frequency shirt.  When the target is in the rar field of the laser antenna, and ir the antenna beam is larger  than the target, the usual form of the simple radar equation of Sec. 1.2 applies. 
 59. M. Sachidananda and D. 
 This will make B’s anode go  4X4 (.e., 4) volt positive. This extra } volt at B’s  anode will cause a further change of } x} (Z.e., vg) volt  at A’s grid, and so on. Mathematical proof exists that  the resulting change can never exceed 13 volts, for this  total is made up by continued addition of 1-+3-+75, and  so on, each term being one-quarter of the preceding  one. 
 Further, there are conditions where an antenna that is well matched at broadside may have some angle of scan at which most of the power is reflected. The variation in element impedance and element pattern is a manifestation of the mutual coupling between radiating elements that are in close proximity to one another. For a practical design, two empirical techniques are of great value: 1. 
 Let the bounding plane between the medium and airbeatz=O. The solution ofMaxwell’s equations which represents aplane wave incident onthebounding surface, awave reflected from the surface, and awave transmitted into themedium isgiven by. PROPERTIES OF RADAR TARGETS [SEC. 
 K. 11.: Optimization of Tilt Angle and Element Arrangement for Planar Arrays, Microwat~e  .I., vol. 14. 
 5. The dissipated power capability of the power combiner terminations should be sufficient to accommodate any combination of power amplifier failures. 6. 
 The use of the diode for D.C.  restoration is described in the Amateur Radio Handbook,  in the section on television technique. But in concluding  this brief survey of some unusual radar circuits which  . 
 TRACKING ERROR FOR LARGE TARGETS IS ILLUSTRATED BY  THE EXAMPLE IN &IGURE  )N &IGURE  A  THE TYPICAL GAUSSIAN 
 16.19. Delay-line Signal Circuits.-The delay line isalow-impedance device with alarge attenuation; itismechanically awkward tomount the line physically close tovacuum-tube circuits. These facts combine to make thedelay process electrical yexpensive. 
 VI (S Band) Investigation of Performance in Service, TRE Report T1863 (TNA AVIA 26/865) [12] Performance of A.S.V. Mk. VI in Wellington XIV aircraft, C.C.D.U. 
 The former combination isoutlined inFig. 1722, inwhich some parts peculiar tothis system and not heretofore described areshown. Itisnecessary toprovide the azimuth data interms ofcompass directions rather than aircraft heading. 
 5.7ACQUISITION /\tracking radarmustfirstfindandacquire itstargetbeforeitcanoperate asatracker. Therefore iti9.-.usually necessary fortheradartoscananangular sectorinwhichthepresence ofthetargetissuspected. Mosttracking radarsemploy anarrow pencil-beam antenna. 
 DOMAIN  WEIGHTING FUNCTIONS . 
 The two omitted entries on the "Cosite" row are technical constraints: to generate a sufficiently large bistatic radar constant for cosite operation the transmitter design and operation must be optimized for bistatic radar use; hence the dedicated transmitter is often the only viable cosite configuration. Exceptions to this rule include exploiting HF ground- wave propagation and occasional atmospheric ducting. Isorange Contours. 
 A single sinusoidal component of a complex surface is shown with an incom- ing radar wave at angle of incidence 6. The radar wavelength is X, and the surface-component wavelength is A. When the signal travels an extra distanceCorrelation coefficient e-*L* e~^ILPower expression K e-(L2/2ah2) tan2 0 sin 0 m (1+Ain'e\-» cos2 6 sin e \ cos4 6/Reference 42 33 . 
 S. P. Applebaum, P. 
 Kurose, F. Junyent, B. Philips,  S. 
 S. Locke, Guidance,  Princton , NJ: D. Van Nostrand Company, 1955, Chap. 
 53. Harrington, J. V.: An Analysis of the Detection of Repeated Signals in Noise by Binary Integration,  IRE Trans.. 
 Ingeneral, the load variations correspond toavery irregular path onthe Rieke diagram whose behavior isunpredictable. Asafe policy indesign istoestimate themaximum variation inVSWR tobeexpected from ther-fcircuits, and toemploy aloading ofthemagnetron which does notproduce afrequency change too large tobeaccommodated bythe radar receiver even when this variation inVSWR isofsuch acharacter astoproduce themaximum possible frequency shift. Appreciation oftheeffects ofther-fload ontheperformance ofmag- netrons has contributed more than any other single factor tomagnetron reliability. 
 Signal Frequency Amplitude of Spectral Component −5w A5(c − d)/32 −3w A3(a + b)/8 + 5A5 (c + d)/32 −w A(∆/2) + 3A2 (a − b)/8 + 5A5 (c − d)/16 (Input)w A(1 + ∆/2) − 3A2(a + b)/8 − 5A5(c + d)/16 +3w A3(a − b)/8 + 5A5 (c − d)/32 +5w A5(c + d)/32TABLE 6. 2 Spurious Signal Components Generated by I/Q Nonlinearity ch06.indd   34 12/17/07   2:03:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 As mentioned earlier, when the digital phase samples include the carrier component, the / and Q components are centered on this carrier fre- FIG. 10.3 Digital waveform generation.MRVEFORM SELECTION MRVEFORM PHRSE STORRGE OR PHRSE GENERRTIOND/R CONVERSIONSRMPLE RND HOLDLOM PRSS FILTERSSINGLE SIDEBRND BRLRNCED MODULRTORSSUM . quency and the low-pass filter can be replaced with a bandpass filter centered on the carrier. 
 D. A. Fulghum, “See it, jam it, kill it” Aviation Week & Space Technology , pp. 
 The amplitude and phase modulation functions vary  slowly compared to the period of the carrier (1/ f0). Consequently, x(t) is a narrowband  waveform with a bandwidth that is small compared to the carrier frequency .  Complex Envelope. 
 H..H.J.Prager. E.L.Allen,Jr..andV.A.Mikenas: Advances inHighPower,S-Band Trapall-Diode Amplifier Design,Microwave i.,vol.17,pp.41-44,February, 1974. 37.Cohen.E.D.:Trapalls andImpalls: Current StatusandFutureImpactonMilitary Systems, IEEE EASCON'75, pp.130-Ato130-G. 
     ( "'&       
 AMBIGUOUS MODES WITH SIGNIFICANT CLUTTER IN ALL RANGE CELLS )F THE CLUTTER AND JAMMER CANNOT BE SEPARATED  EITHER IN RANGE OR DOPPLER DOMAINS  THEN A TWO 
 Batch processor, 7.8 to 7.11 Battle of the Pips, ducting effects, 26. 9 Beacon equation, 24.4 Beacon rendezvous, 5.27 Beam-shape factor, 7.3 Beam-shape loss, 4.40 Beam-splitting angle accuracy, 7.5 to 7.7 Beam steering, 13.15 to 13.19 Beam steering control, 5.10 Binary integrator, 7. 7 to 7.8, 7.12 to 7.13 Birds, and MTI, 2.96 to 2.98 Bistatic plane, 23.3 Bistatic radar applications, 23.9 to 23.14 benchmark range, 23.4 to 23.5 concept of, 23.1 to 23.3 coordinate system, 23.3 to 23.4 doppler in, 23.14 to 23.17 floodlight beams, 23. 
 Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 17 .22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 ● Crossrange resolution for stripmap SAR:  δλ θλ λcr≈ ≈ =2 2 2 ∆ ( / )DD (17.36) ● Image Collection Time: tA = lR/(2Vdcrcosqsq) ● PRF: fR = PRF ≥ 2V/D (V = platform velocity) ● PRF limits for unambiguous range, fR < c/2R:  2 2V Dfc RR≤ <  (17.37)  For stripmap SAR,  S c V δ ψcr≤( .) cos 4 7 (17.38) ● Signal-to-noise ratio:  SNRP G R kT F Vr= =Tx-avg Loss2 3 0 3 3 0 2 4λ σ δ π ψ ( ) ( ) cosP P A R k T F Vr Tx-avg Loss2 2 0 3 0 8η σ δ π λ ψ ( ) cos (17.39) 17.8 SPECIAL SAR APPLICATIONS In this section, we briefly discuss several specific aspects of SAR, specifically polari - metric SAR, moving targets, vibrating targets, measurement of object height, and foli - age-penetration SAR. Polarimetric SAR. 
 AP- 16, p. 360,  May, 1968.  03. 
 Most areas have large numbers of vehicles and scatterers that could be vehicles. It is  typical to have up to 20,000 bona fide GMTs in the field of view. Processing capacity  must be adequate to handle and discriminate thousands of high SNR threshold crossings  and hundreds of moving targets of interest. 
 DIMENSIONAL IMAGES OF OBJECTS UP TO  METERS BELOW THE SURFACE OF LAND AND SEA 3UCH A DEVICE WOULD ALLOW VERIFIERS TO IDENTIFY UNDERGROUND WEAPONS FACILITIES  LIKE THOSE OF CONCERN IN ,IBYA  )RAQ  AND .ORTH +OREA 4HE UNDERWATER DETECTION CAPABILITY COULD ALSO BE USED TO VERIFY TREATIES DEALING WITH SUBMARINES AND NUCLEAR WEAPONS POSITIONED ON THE SEABEDv (OW WELL  &)'52%  'ENERAL SYSTEM OPERATION OF '02 SHOWING TARGETS AND SOURCES OF CLUTTER #OURTESY )%%  . Ó£°È  2!$!2 (!.$"//+  '02 WOULD PROPAGATE THROUGH SEAWATER IS AN INTERESTING QUESTION GIVEN THE KNOWN  ATTENUATION OF SEAWATER AT RADAR FREQUENCIES ! CAREFUL ANALYSIS OF SOME OF THE CLAIMS ABOUT THE SAME RADAR WAS PUBLISHED BY 4ULEY  AND IS INTERESTING READING Ó£°ÓÊ *9- -Ê"Ê*,"*/" Ê Ê / 
 3.39 Performance Characteristics  ..............................  3.40  Multiplexing  .......................................................  3.41  3.12 I/Q Distortion Effects and Compensation  Methods  .................................................................. 
 Fifth, there are fewer options for radi - ating multiple waveforms simultaneously from the same transmitting facility. And  sixth, for high power HF radars, the additional power density associated with pulse  waveforms in the ionosphere may, in principle, cause self-modulation from non - linear effects. 20.6 THE TRANSMITTING SYSTEM Transmitters. 
 With the same 254. Sensors 2019 ,19, 346 SNR, the percentage error is greater for targets that have higher degree of anisotropy. When we judge whether a target is anisotropic or not, we only interested in whether there are any high scatterings in some angles. 
 Tang and O. H. Shemdin, “Measurement of high-frequency waves using a wave follower,”  J. 
 4ARGET 4RACK UPDATES  A SINGLE 02& WAVEFORM CAN BE USED  4HE RANGE ANDOR DOPPLER AMBIGUITIES  ARE RESOLVED IN SEARCH AND   IF NECESSARY  IN THE  4 RANSITION 
 BAND  THREE 
 ART 7 
 The twooverlapping antenna beamsmaybegenerated withasinglereflector orwithalens antenna illuminated bytwoadjacent feeds.(Aclusteroffourfeedsmaybeusedifboth elevation- andazimuth-error signalsarewanted.) Thesumofthetwoantenna patterns of Fig.5.7aisshowninFig.5.7b,andthedifference inFig.5.7c.Thesumpatterns isusedfor transmission, whileboththesumpatternandthedifference patternareusedonreception. The signalreceived withthedifference patternprovides themagnitude oftheangleerror.Thesum signalprovides therangemeasurement andisalsous~dasareference toextractthesignofthe errorsignal.Signalsreceived fromthesumandthedifference patterns areamplified separately andcombined inaphase-sensitive detectortoproducetheerror-signal characteristic shownin Fig.5.7d. Ablockdiagram oftheamplitude-comparison-monopulse tracking radarforasingle angularcoordinate isshowninFig.5.8.Thetwoadjacent antenna feedsareconnected tothe twoarmsofahybridjunction suchasa..magicT,"a..ratrace,"orashort-slot coupler. 
 LOOK  
 The gain of the reflector antenna is one of its most  important parameters. It is convenient to describe the reflector antenna gain with ref - erence to the fundamental gain limit an aperture of area A. This limit, applicable to  aperture antennas of sufficient electrical size (approximately 25 square wavelengths  or greater), is the so-called aperture gain Gap,  GA ap=4 2π λ (12.6)−20−15−10−505101520 −20−15−10 −5 0X zaedge fDrXX a FIGURE 12.1  Parabolic reflector in x-z plane ch12.indd   4 12/17/07   2:30:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Considerable usehas been made ofradar beacons. These ,aredevices which, onreceiving apulse oraseries ofproperly coded pulses from a radar set, will send back inreply apulse oraseries ofcoded pulses. A great increase intheflexibility and convenience oftheuseofradar under certain conditions can beobtained bytheuse ofsuch beacons. 
 The previous methods all have some drawbacks and are mainly applied in raw echo data. There are two issues involved in processing raw echo data. One is that the aforementioned methods are often applied to raw echo data, while the moving ship’s position is hard to ascertain in raw data [ 6]. 
 PROBING RADAR AND SOME RECENT EXPERIENCE v IN  0ROC #ONF  3UBSURFACE %XPLORATION FOR 5NDERGROUND %XCAVATION AND (EAVY #ONSTRUCTION   !MER 3OC #IV  %NG    PP n   * # #OOK  h2ADAR TRANSPARENCIES OF MINE AND TUNNEL ROCKS v  'EOPHYS  VOL   PP n       + # 2OE AND $ ! %LLERBRUCH  h$EVELOPMENT AND TESTING OF A MICROWAVE SYSTEM TO MEASURE COAL  LAYER THICKNESS UP TO  CM v .AT "UR 3TDS  2EPORT .O32 
 Over a quasi-flat sea, a pulse-limited altimeter’s idealized mean  FIGURE 18.8  (a) The altimeter’s pulse (typically 0.5 m long after  compression) sequentially encounters oceanic surface waves (of height  up to 20 m or more). ( b) Sea-surface height (SSH) corresponds to the  midpoint of the waveform’s leading edge, significant wave height  (SWH) to the slope of the leading edge, and wind speed (WS) to the  (inverse) backscattered power. The waveforms depicted here are ideal - ized; useful “smoothness” requires 1000 or more incoherently aver - aged radar returns. 
 DENCE OF THE PARAMETERS DEFINING THE DISTRIBUTION TO THE RAIN RATE AND TO THE TYPE OF RAINFALL 4HERE IS LITTLE EVIDENCE THAT RAIN WITH A KNOWN RATE OF FALL HAS A UNIQUE DROP 
 At that point the sweep was terminated and the discriminator regained control. In addition a manual control was also provided that could override the AFC system.Operator control of the AFC system was achieved using control unit type 498, ﬁgure 4.16. 4.4.2 Attenuator type 58 The need to continuously adjust the attenuator control during a homing run was another load on the operator. 
 RATING THE INHERENT SHORT 
 H this assumption is not applicable,  a doppler frequency shift will be· superimposed on the FM range beat note and an erroneous  range measurement results. The doppler frequency shirt causes the frequency-time plot of the  echo signal to be shifted up or down (Fig. 3.12a). 
 138. M. W. 
 Green, C. R., et al.: A 2-Watt GaAs TXfRX Module with Integral Control Circuitry for S-Band Phased Array Radars, IEEE MTT Symp. Dig., pp. 
 The relaxed brightness constraint error is: /epsilon1I=/integraldisplay/integraldisplay (It+Ir·rt−Im t−ct)2dx dy . (6) Equation ( 6) can be combined with the other constraint errors to produce the ﬁnal functional to be minimized: /epsilon1total=/epsilon1I+λs/epsilon1s+λm/epsilon1m+λc/epsilon1c, (7) where λs,λm, and λcare error weighting coefﬁcients. The remaining errors are given as: /epsilon1s=/integraldisplay/integraldisplay ||∇rt||2 2dxdy , /epsilon1m=/integraldisplay/integraldisplay ||∇ mt||2 2dxdy , /epsilon1c=/integraldisplay/integraldisplay ||∇ ct||2 2dxdy . 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 Compensation for Scanned Impedance Variation. 
 Grant and B. S. Yaplee, “Backscattering from water and land at centimeter and millimeter  wavelengths,” Proc. 
 Varying the velocity of  propagation by varying the permeability is the basis of ferrite phase shifters. Gas discharge and  ferroelectric phase shifters are examples of devices that depend on changes in dielectric con-  stant to vary the velocity of propagation, and hence the phase. The velocity of propagation  may also be varied in a more direct manner as in the Eagle, or delta-a, scanner where the  narrow wall of a waveguide is moved mechanically to produce a change in phase and a  scanning beam.20  Many phase-shifting devicesare reciprocal in that the phase change does not depend on  the direction of propagation. 
 The matched­ filter frequency-response function may similarly be written in terms of its amplitude and phase  spectra I H(J) I and exp [ -j<J>m(J)]. Ignoring the constant Ga, Eq. ( 10.1) for the matched filter  may then be written as  or  and I H(J) I exp [ -j<J>m(J)] = I S(J) I exp {j[ </>J(J) -2nft i]}  IH(J)I = IS(J)I  <Pm(f) = -<j,s(J) + 21tft1 (10.2)  (10.3a)  (10.3b) . 
 the  loss is 1.96 dB.  The beam-shape loss considered above was for. a beam shaped in one plane only. 
 Typical values of B at X band, in rela - tively turbulent air, range from about 1.0 Hz for small aircraft to about 2.5 Hz for larger  aircraft. B changes in proportion to radar frequency provided that the target span is at  least a few wavelengths. Again, long time samples are necessary to obtain a relatively  smooth spectrum from measured data. 
 White, W. D.: Synthesis of Comb Fiiters, Proc. Natl. 
 FIGURED ON A TRAILER FOR DEPLOYMENT 4HE !.403 
 BIT COMPLEX NUMBERS  AND IF WE ASSUME THAT THE MAGNITUDES OF THE COMPLEX NUMBERS DO NOT EXCEED  BITS  THEN THE FINAL &&4 OUTPUTS COULD GROW  BITS COMPARED TO THE INPUTS  SO THE &&4 COMPUTATIONS COULD BE PERFORMED WITH  BIT OR LARGER ADDERS 4HIS ALSO MEANS THAT THE MULTIPLIERS WOULD HAVE TO HANDLE THE LARGER NUMBER OF BITS ON THE INPUTS 4HIS METHOD COULD GET UNWIELDY FOR LARGE &&4S !NOTHER TECHNIQUE IS TO AUTOMATICALLY SCALE THE OUTPUTS OF EACH STAGE BY A FACTOR OF    WHICH WOULD NOT ALLOW THE OUTPUTS TO GROW 5NFORTUNATELY  THIS WOULD ALSO LIMIT ANY PROCESSING GAIN THAT THE &&4 MIGHT OFFER ! THIRD METHOD  CALLED  BLOCK FLOATING POINT   CHECKS THE MAGNITUDES OF ALL THE OUT 
 Tomlinson, and J. McCorkle, “Antenna mea - sures of merit for ultra-wide synthetic aperture radar,” in Proceedings of the 1998 IEEE Radar  Conference , 1998, pp. 331−336. 
 TER OVER A REGION OF UP TO  o RELATIVE TO THE TARGETS VELOCITY VECTOR !GAIN  THESE  CONDITIONS ARE FOR AN ASSUMED COLLISION COURSE !S IS EVIDENT  THE ASPECT ANGLE OF THE TARGET CLEAR OF SIDELOBE CLUTTER IS ALWAYS FORWARD OF THE BEAM ASPECT !MBIGUITIES AND 02& 3ELECTION  0ULSE DOPPLER RADARS ARE AMBIGUOUS IN RANGE  AND POSSIBLY DOPPLER !S MENTIONED EARLIER  THE UNAMBIGUOUS RANGE  2 U IS GIVEN BY  CF2   WHERE C IS THE SPEED OF LIGHT AND F2 IS THE 02& )F THE AIRBORNE TARGET RADIAL VELOCITY TO BE OBSERVED IS BETWEEN  64 MAX OPENING FOR  OPENING TARGETS POSITIVE RANGE RATE  AND  
 578 INDEX  Parallel-plate feed, 309  Parametric amplifier, 351  Passive TR-limiter, 363, 364  Pattern synthesis, 254-258  Penetration color tube, 357  Performance chart, magnetron, 195-197  Performance figure, radar, 63  Permanent magnet focusing, 202  Phase-coded pulse compression, 428-431  Phase-comparison monopulse, 165-167  Phase detector, in MTI, 105  Phase-frequency array, 303, 334  Phase-in-space 30 radar, 543  Phase-phase array, 335  Phase-sensitive detector, 156, 160  Phase shifter quantization, 321-322  Phase shifters, 286-298  Phased array antennas, 278-337  Phasers, 287  Pi mode, magnetron, 193  PIN diode, 290  Pincushion radar, 316  Pipology, 387  Plumbing loss, 57-58  Polarization:  antenna, 227  circular, 504-506  for target classification, 436  Polarization agility, and glint reduction, 172  Polarization-twist Cassegrain, 242-243  Polyphase codes, 432  Postamplification beam forming, 310-311  Postdetection integration, 29-32  Power gain, antenna, 225-226  Protector TR, 364  Power programming, in 30 radar, 302  PPI, 6, 355  Precipitation:  attenuation by, 503  scattering from, 498-503  Predetection integration, 29  Prelook receiver, 548  Probability density function, 20-23  Probability distribution function, 23, 26  Probability of detection, 27-29  cumulative, 64  for Swerling models, 48  Probability of false alarm, 24  Propagation of radar waves, 62, 441-461  Propeller modulation, 76  Proximity (VT) fuze, 71  Pseudorandom code, 429  Pulling figure, magnetron, 199  Pulse chasing, in bistatic radar, 559 Pulse compression, 420 434  and frequency scan, 303  Pulse compression ratio, 422  Pulse doppler radar, 139-140  Pulse-forming network (PFN1 214  Pulse repetition frequency, 2  staggered, 114-117  Pulser, 214  Pushing figure, magnetron, I 96  Quadrature channel, in MTI, 119  Quadrature component, in monopulse, 176  Quantization:  in MTI, 120 . J  in phase shifters, 321-322  Quantization error, FM-CW altimeter, 87  Quantization lobes, 321-322  and triangular spacings, 334  Rabbit-ear oscillations:  in CFA, 211  in TWT, 207, 208  RAOAM, 437  Radar applications, 12-13  Radar block diagram, 5-7  Radar cross section, 33-46  aircraft, 39-44  bird, 509  bistatic, 557-559  cone-sphere, 35  definition, 4, 33  example values, 44  fluctuation models, 46-52  insect, 510  man, 44  reduction of, 553  .rod, 34-35  ships, 142-143  sphere, 34  and target classification, 435  Radar definition, 1-2  Radar frequencies, 7-8  Radar equation, 17-65  bistatic, 556-557  derivation of, 3-4  laser, 565-566  0TH, 530-531, 535  SAR, 521-522  surface clutter, 471-474  surveillance, 64  for weather radar, 499-500  Radar history, 8-12  Radar operator, 386-387 . Radial velocity direction, in CW radar, 78-79  Radiation hazards, 465-466  Radiation intensity, 224  Radiation pattern:  antenna, 224, 228-235  array, 280-282  Radomes, 264-270  Rain:  and radomes, 269-270  scattering from, 500-502  at millimeter waves, 564  Random errors:  in array antennas, 318-322  in reflector antennas, 262-264  Range accuracy, 401-407  Range ambiguities, 53-54  Range-gate stealer, 551  Range-gated doppler filters, 117-119  Range measurement, in CW radar, 95-98  Range resolution. 
 .ismooth surface on the ground appears asablack area inthe radar picture, while arough surface appears bright incontrast, Inthe case ofthe smooth surface, the incident radiation isdeflected away, asinFig. 316. l~here the ground isrough, the incident raciiation isscattered inalldirections, as (a) inFig. 
 Any military radar that is suc - cessful can expect a hostile adversary to employ countermeasures to reduce its effec - tiveness. Operating over a wide range of frequencies makes countermeasures more  difficult than if operation is at only one frequency. Against noise jamming, changing  frequency in an unpredictable manner over a wide range of frequencies causes the jam - mer to have to spread its power over a wide frequency range and will, therefore, reduce  the hostile jamming signal strength over the bandwidth of the radar signal. 
 94–102, February 1985. 12. H. 
 NOISE SPECTRUM IS SIMILAR FOR BOTH LARGE AND SMALL TARGETS 4HIS IS BECAUSE THE RATE OF RELATIVE RANGE CHANGE IS A  FUNCTION OF BOTH ANGULAR  YAW AND DISTANCE FROM THE CENTER OF GRAVITY OF THE AIRCRAFT 4HUS  A LARGER AIRCRAFT WITH SLOW YAW RATES BUT GREATER WINGSPAN GENERATES A LOW 
 48, pp. 663-669.  April, 1960. 
 For larger values of s/X, grating lobes occur at angles G1, given by sin G1 = sin G0 ± -y- (7.10) S/\ where n is an integer. In the limit, the inequality (7.9) does allow a grating-lobe peak to occur at 90° when scanning to G0. Even though the grating lobe is reduced when multiplied by . 
 (1), (2), and (3)weobtain Rm.~P$~T54 v,~, holding other parameters constant, or R~nx=Prvji. (4) The average power output isgiven byPrv,. Itisdesirable todrive thetransmitter ofahigh-performance ground- based system atthe highest pulse power and the highest average power that itwill safely withstand. 
 A300-Mc/sec Amplitude-modulated Equipment.—Largely because ofitsavailability, thetype ofr-fequipment most used atRadia- tion Laboratory consists ofamodification ofanamplitude-modulated television transmitter-receiver combination operating inthe 300-Mc/sec region (specifically onany of10channels between 254 and 372 Me/see). The transmitter provides 90watts ofpeak video signal power, and 250 watts ofpulse power. Ablock diagram ofthe transmitter isshown inFig. 
 5.1 Cross section of a microwave bipolar transistor chip. (Reprinted with permission from E. D. 
 vol. 5. pp. 
 (The uncertainty of the data  ought to have been indicated in tl1i& figure by making the vertical thickness of each curve at  least ± 3 dB wide. Th~s was not done so as to avoid the confusion that would be caused by the  wide overlap of the curv~s.) . ' . 
 TO 
 CENTERED TO THE RIGHT OVAL IN &IGURE D AND TRANSMITTER 
 6.4, is similar to that of the  corlventional magnetron, and the electron and RF operations that take place in the interaction  space are the same for both types of magnetrons. The differences between the two are in the  more effective mode control of the coaxial cavity as compared to that offered by conventional  strapping.  In the i~toerted coa-xial nragnetrolt the cathode surrounds the anode. 
 ch10.indd   7 12/17/07   2:19:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. The Radar Transmitter. 
 ING TEST SIGNALS DURING RADAR DEAD TIME OR DURING SOME SCHEDULED CALIBRATION INTERVAL #ALIBRATION COEFFICIENTS CAN BE STORED AS A FUNCTION OF COMMANDED ATTENUATION  OPERAT 
 #   ! " 
 PRODUCT DEVICES PRODUCING THE OUTPUT VOLTAGE   EE  \\\\ \\\\ \\3$3$$ 3COS OR COS QQ   WHERE E    ANGLE 
 After topographic phase removal, 106 differential interferograms are generated, see Figure 3. The signal-to-noise ratio is improved by performing multi-looking factors of 4 ×4 in the range and azimuth directions, and Goldstein ﬁltering method. Figure 3. 
    "N  . 
 $ELAY 3CANNING  0HASE SCANNING WAS SEEN TO BE FREQUENCY 
 vol.47.pp. 177183,April,1977. 35.Moore. 
 In this case a coherent pro- cessing interval of CPI = nine pulses was assumed, and the limitation due to thermal noise was ignored by setting the clutter level at 100 dB above noise. It should be kept in mind that Eq. (15.21) for the optimum weights will yield a different result for each different target doppler shift, so that a large number of 1 STAGGER (CL) (dB) Va=IO KNOTS V8 = 30 KNOTS VB=SOKNOTS VB= ioo KNOTS VB=SOOKNOTS . 
 45 to 20.49 resource management, 20.54 to 20.55 revisit times, 20.4 to 20.5 signal processing, 20.49 to 20.54 sky wave radar design, 20.8 to 20.13 spectrum occupancy, 20.40 to 20.45 surface-wave radar, 20.70 to 20.76 tracking, 20.53 to 20.54 tra nsmitters, 20.23 to 20.26 waveforms, 20.21 to 20.23 P PALSAR, 18.11, 18.15 to 18.16 Parabolic cylinder antenna, 12.18 to 12.19 Parabolic equation methods, for propagation, 26.16 Parabolic reflector antenna, 12.17 to 12.18 Passive bistatic radar, 23.29 Passive ECM, 24.5 to 24.6 Passive listening, 5.34 Patriot radar, 13. 66 to 13.67 Pave Paws radar, 11.31 to 11.32 Penetration aids accompanying ballistic missiles, 24.6 Phase-comparison monopulse, 9.11 to 9.12 Phase instabilities, 2.66 to 2.70. Phase noise in pulse doppler, 4.28 to 4.30 Phase shifters, 13.51 to 13.53 Phased array radar active aperture, 13.53 to 13.55 antennas, 13.2 to 13.3 AN/SPY-1, 13.62 AN/SPY-3, 13.69 aperture matching, 13. 
 FIC SURVEILLANCE 3CIENTIFIC APPLICATIONS INCLUDE MEASUREMENT OF PLANETARY SURFACES AND ATMOSPHERES AND STUDY OF IONOSPHERIC TURBULENCE %XAMPLES ARE GIVEN IN 3ECTION  7HILE THESE EXAMPLES ARE BOTH CREDIBLE AND USEFUL  THEY ARE NICHE APPLICATIONS WHEN COMPARED TO THE UBIQUITOUS CAPABILITIES OF MONOSTATIC RADARS  WHICH REMAIN THE PRIN 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°xÎ £n°xÊ - // 
 Heard. C. I.: Coherent and Incoherent Scattering of Microwaves from the Ocean, IRE Trans.,  vol. 
 The radar operator needs a model with enough sophistication to per- mit full interpretation of the real-time soundings for both operating parameter se- lection and data analysis. The regions of the ionosphere that are considered necessary to model for an understanding of transmission paths are as follows: 1. D region: This region occupies the lowest altitudes considered. 
    .   '2/5.$ 0%.%42!4).' 2!$!2   Ó£°Ó  D" TO  D" ! FURTHER DEVELOPMENT OF THE 4%- HORN IS GIVEN BY -ARTEL IN WHICH  THE ANTENNA IS COMPOSED OF A SET OF SPREAD hFINGERSv FORMING THE SHAPE OF A HORN AS  SHOWN IN &IGURE  %ACH FINGER IS A WIRE WITH A DIAMETER OF  MM AND IS RESIS 
 SCANNED SPECTRAL COMPONENTS &OR A BEAM SCANNED TO n  THIS BECOMES   "ANDWIDTH      BEAMWIDTH n   PULSE   .OTE THAT THIS IS TWICE THE BANDWIDTH PERMITTED FOR THE #7 SITUATION !NOTHER WAY OF  ANALYZING THIS PHENOMENON IS IN TERMS OF APERTURE FILL TIME !S SHOWN IN &IGURE   THE TIME IT TAKES TO FILL THE APERTURE WITH ENERGY IS   T , CSINP  )F THE BANDWIDTH IS CHOSEN TO BE EQUAL TO THE APERTURE FILL TIME  S   , C SIN P  THIS  IS EQUIVALENT TO BANDWIDTH       BEAMWIDTH  n  (ENCE  A LOSS OF  D" CAN BE  EXPECTED IF THE PULSE WIDTH IS EQUAL TO THE APERTURE FILL TIME ,ONGER PULSES WILL HAVE  LESS LOSS 4HE EXACT AMOUNT OF THE LOSS WILL DEPEND ON THE SPEC IFIC SPECTRUM TRANSMIT 
 8 IS THE FIRST CIVILIAN DEDICATED SPACE 
 Asafety switch prevents turning onthemagnetron unless the guide isinproper position. This piece slides out ofthe way and amatched probe-fed transition piece slides inforintroducing atest signal. The receivers aretypical ofground and ship sets, except that inthis case they donotcontain theregulated power supplies. 
 19.Upton,L.O.andG.J.Mayer:Charge-coupled DevicesandRadarSignalProcessing. RCAEngr..vol. 21.no.I.pp.30-34.June/July, 1975. 
 Atorientations 180° apart, theloop picks up Negative video 3.stagavideo HRaflectometar signalsandpulses amplifiar I I Cathode followerwithMaster d.crastoreroscillator -v IPulse Modulation transformer— diode I I& Synchronization 4.stsgevideo Highvoltaga pulsas amplifier transformer (a)Transmitter a‘;“-VideoVideo Tunedcavity Detector cathodaVideosignal amplifierfolloweroutput R-f3stages ofifInvarse amplifiers faedbackAmplifier amplifiers I I \I 3:::? ConverterCathoda amplifiersfollower 1 I t R.f Cathode oscillator followar Estsrnal radarIAGCIoOp interference suppression (b)Receiver FIQ. 17.17 .—3OO-Mc/sec amplitude-modulated equipment. the outgoing power and the reflected power respectively. 
 68. A. Farina, R. 
 262- 264  Fvaporation duct, 453 455  1:xponcrttial probability density function, 23  Externally collerent MTI, 138  False alarm, 17  False alarm number. 30  False alarm probability. 24  False alarm time, 24-26, 32  Far field. 
 The ratio improves forsmaller nand vice versa. Ifthe signal being relayed isthe firing time ofthe modulator, the firing should, ifpossible, coincide with thetransmission ofthethird pulse. Ifthe modulator can betriggered with sufficient accuracy, the output connection indicated in-Fig. 
 This may beaplat- form mounted ongimbals and controlled automatically tocompensate the pitching and rolling ofthe vehicle. Ifthe vehicle rolls much but pitches little, thepitch-gimbal axis may beomitted, and the stable-base stabilization degenerates into roll stabilization. Avery different method ofbeam stabilization ispossible inascanner having itsmain axis always perpendicular tothe floor ofthe vehicle. 
 #7 WAVEFORM IS POSSIBLE BY RELAXING THE CONDITION THAT THE WAVEFORM BE PERIODIC 4HIS IS A POWERFUL TOOL FOR CONTROLLING RANGE 
 The available remedies arethe use ofloose mixer coupling, lossy local- oscillator cable, and separate pickup loops inthelocal-oscillator cavity. Another cause ofrandom components inthelocking pulse isexcessive r-fpulse amplitude atthe locking mixer. Ifthe r-fpulse exceeds the level ofthe local oscillator, self-rectification will take place, yielding a video pulse that will have noncoherent components attheintermediate frequency. 
 3.7).  Although the doppler-frequency spectrum "folds over" in the video because of 1he  action of the detector, it is possible to determine its sign from a technique borrowed from  single-sideband communications. If the transmitter signal is given by  £1 = Eo COS Wot  the echo signal from a moving target will be  where £0 = amplitude of transmitter signal  k1 = a constant determined from the radar equation  w0 = angular freque11cy of transmitter, racl/s  wd = <lopper angular frequency shift  </> = a constant phase shift, which depends upon range of initial detection (3.4)  ( 3.5)  The sign of the doppler frequency, and therefore the direc.tion of target motion, may be found  by splitting the received signal into two channels as shown in Fig. 
 IEEE T rans. Geosci. Remote Sens. 
 Thisisknownasradarsignalmanagement andisanimportant function of thecomputer. IntheAN/FPS-85 satellite-surveillance radar,forexample, sevendifferent radar waveforms wereavailable forperforming thetargetdetection andtracking missionasshown inTable8.1.118Aneighthwaveform wasllsedforalignment ofthetransmitter andreceiver modules. Thesearchallddetectioll function requires thatthecomputer generate theangularcoor­ dinatesoftheregiontobesearched, the typeoftransmitted waveform tobeused,thelengthof thedwellperiod,andthetimeassigned fortheexecution ofthedwellbytheradar.Sincethe radarisperforming tracking andotherfunctions aswellassearch,conflicts inscheduling the radarortheprocessor mightarise.Tracking functions areoftenmorecriticaloftimethan search.andwouldhaveahigherpriority intheeventofascheduling conflict. 
 A particular complication of shipborne radar arises because  the antenna is mounted on an unstable moving platform. This movement has six  components—three translational and three rotational, all of which are typically varying.  The motions are complex; the translational components are surge, sway, and heave, and  the rotational are roll, pitch, and yaw. 
 11. K. C. 
 XIIID would be further developed after the war for use as ASV 13 in the Avro Shackleton MR aircraft, which entered service in 1951. 8.2 The schnorkel The ASV installations in operation at the end of the war were only generallyeffective against surfaced U-boats. Detection of schnorkel tubes was only possible at short ranges in calm seas. 
 ¤ ¦¥³ µ´  #ONSTANT  MANEUVERA UNITS OF GS ,AG BIAS  IN PREDICTED TRACK STATE A4 BA4A B ¤ ¦¥³ µ´ 4!",%  #HARACTERIZATION OF 4RACKING %RRORS AS A &UNCTION OF 4RACKING 'AINS @  AND A. 
 FREQUENCY DISTRIBUTIONSnA REVIEW v  0ROCEEDINGS OF THE )%%%  VOL   NO     *ULY   2 'UARINO AND 0 )BSEN  h)NTEGRATED '03).33!2'-4) RADAR PRECISION TARGETING FLIGHT TEST  RESULTS v IN 0ROCEEDINGS )NSTITUTE OF .AVIGATION '03 
 Ê+1 /9 )T IS CLEARLY IMPORTANT FOR A 3!2 TO PRODUCE HIGH 
 The availabi lity of digital  waveform synthesis when transmitting, and a digital matched filter approximation when r e- ceiving, are making it possible to synthesize a system with very low mismatch loss, low peak  side lobes, low integrated side lobes, and good Doppler tole rance. Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  124     In this paper waveform design and signal processing, which will result in low range -time side  lobes and a low mismatch loss, are addressed along with the practical co nstraints of the an a- log-to-digital (A/D) conversion process and digital filtering. The r equired A/D converter - sampling rate determines the feasibility and resulting dynamic range of the signal processor  implementation and therefore requires careful attention. 
 Since the ﬁrst line ofminima is at the surface of the sea, the ﬁrst region of minimum radiation orenergy is adjacent to the sea’s surface. From ﬁgure 1.5 it should be obvious that if r-f energy is to be reﬂected from a target, the target must extend somewhat above the radar horizon, theamount of extension being dependent upon the reﬂecting properties of thetarget. A VERTICAL-PLANE COVERAGE DIAGRAM as illustrated in ﬁgure 1.5isusedbyradardesignersandanalyststopredictregionsinwhichtargetswill and will not be detected. 
 For example, the frequency-niodulated pulse waveform whose  ambiguity diagram was shown in Fig. 1 1.12 is the widely used calrirp pulse-compression  waveform. The other approach is to consider the modi~lation applied to a long pulse as  providing distinctive marks over the duration of the pulse. 
 70. D. A. 
 In later phases of processing, doppler  frequency analysis narrowed the effective footprint to 10 km by 40 km. The altimeter  operations (interleaved with those of the imager) resulted in the first radar altimetric map  (of the northern 1/3) of Venus comprised of more than 400,000 individual measurements.  The communications system used a dedicated 2.6 m radio dish antenna. 
 Since the ionosonde could directly observe the electron densities under the peak height, we were then able to derive the TEC of the topside proﬁle by subtracting the TEC of the bottomside proﬁle from the PolSAR TEC. This topside TEC could then be used to help model the electron density topside proﬁle. To evaluate our method, we managed to ﬁnd an ISR which was also located in the same area as the ionosonde station. 
 HORIZON /4(  RADAR CAN HAVE A SITE SEPARATION OF  KM OR MORE TO ACHIEVE ADEQUATE TRANSMIT SIGNAL ISOLATION "UT THAT SEPARATION IS SMALL COMPARED TO THE TARGET RANGE OF THOUSANDS OF KILOMETERS  AND THE RADAR AGAIN OPERATES WITH MONO 
 VIA in a Wellington XIV [ 10]. Figure 4.18. Attenuator rate control unit type 492 [ 6]. 
 6. B. D. 
 but for 55 nmi free-  space range; (5) same as (2), but for  27.5 nrni free-space range; (6)contour  defining start of diffraction region.  (Courtesy Proc. IRE.)  458INTRODUCTION TORADAR SYSTEMS wavelengths, thegeometrical horizon represents theapproximate boundary between there­ gionsofpropagation andnopropagation. 
 15.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 Sea Clutter Lewis B. Wetzel Naval Research Laboratory (retired) 15.1 INTRODUCTION For an operational radar, backscatter of the transmitted signal by elements of the  sea surface often places severe limits on the detectability of returns from ships, air - craft, and missiles, navigation buoys, and other targets sharing the radar resolution  cell with the sea surface. 
 Substituting thisvelocity intotheclassical formula fordoppler frequency shift[Eq.(32)],andu-,ingtheresonant condition Aw=Ar/2,givesthedoppler shift fortheresonant seawavesatgrmngincidence as ./~=±Jg!nA. (14.23) Theplussignappliestotheapprl)arhing resonant wave,andtheminussigncorresponds [0the receding resonant wave.Whentilewindishlowing towardtheradartheapproaching-wave spectral lineISthelargerofthetwo.Whenthewindisblowing awayfromtheradar,the receding-wave spectral lineisthelarger.Whenthewind ISblowing perpendicular to thedirection oftheradarbeam,thetwospectral linesareequal.Thustherelative magnitude ofthetwomajorcomponents ofthedoppler spectrum canprovide ameasure ofthedirection ofthewind.(MoreI'recisely, itdetermines thedirection ofthewavesdrivenbythewindsince thewaveandwinddlrections arenotexactlycoincident.) NotethatinEq.(14.23)thedoppler. OTtIER RADAR TOPICS 535  frequency shift is proportional to tlie square root of the carrier frequency instead of tlie linear  dependence normally characteristic of a doppler shift. 
 Pusey: A Model for Non-Rayleigli Sea Eclio, lEEE Trtit~s.. vol. AP-24. 
 41. Maddix, H.: Clean up in TR Tubes, IEEE Trans., vol. ED-15, pp. 
 $ /PERATIONAL 3UPPORT &ACILITY  ;.OW 2ADAR /PERATIONS #ENTER= v "ULL !M -ETEOROL 3OC  VOL   PP n     4 $ #RUM  2 % 3AFFLE  AND * 7 7ILSON  h!N UPDATE ON THE .EXRAD PROGRAM AND FUTURE 732 
 The polar format is a special case in which the radar collection is performed in a plane. Use of the projection-slice theorem enables one to project the data along any direction. This promises to give images of slices of moving objects. 
 TRAL EMISSIONS REQUIREMENTS  AND IT MAY BE NECESSARY TO SLOW THE RISE AND FALL TIMES (OWEVER  THE AMPLIFIER OPERATING REGION OF OPTIMUM EFFICIENCY OCCURS AS THE TRAN 
 Venus measurements were made by Veneras-9 , -10, Magellan , and Venus  Express .2,52 Figure 23.5 is a simplified schematic of an Earth-based receiver.2 ch23.indd   13 12/20/07   2:21:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 
 3D Volumetric Search. 3D volumetric radar search is possible with elec- tronic scanning in both azimuth and elevation; important regions (e.g., the hori- zon) may be emphasized at will and searched more frequently. The radar may operate with a higher than normal false-alarm rate since targets can easily be con- firmed by repeated interrogation. 
 76. D. E. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°{x 6ENERA   SIMULTANEOUS hTWINv MISSIONS  WERE THE FIRST SPACE 
 SECTION CONCEPT HAS NO MEANING FOR THAT TARGET &OR EXAMPLE  A VERY FINE 
 2M.A.Tuve andG,Breit, “Terrestrial Magnetism andAtmospheric Electricity,” Vol.30,March-December 1925, PP.15-16. Also PhysRev,28,554(1926).. 14 INTRODUCTION [SEC. 
 KM WIDE SWATH ON EACH SIDE  #ALIBRATION DATA TAKEN OVER THE RAIN FOREST WERE USED TO REDUCE ANTENNA GAIN UNCER 
 At each of these positions a signal is transmitted, and the radar signals received in response to that transmission are placed in storage. It is essential that the storage be such that both amplitude and phase of received signals are preserved. After the radiating element has traversed a distance Leff, the signals in storage resemble strongly the signals that would have been received by the elements of an actual linear array. 
 (This is unlike receiver noise since integration of signal pulses and noise can provide  significant improvement in signal-to-noise ratio, as described in Sec. 2.6.) Although the clutter  received during a single scan past a target will be correlated, the sea surface will i~sually change  by the time of the next antenna scan so that the clutter will be decorrelated from scan to scan.  Thus scan-to-scan integration can usually result in an improvement of target-to-clirtter ratio. 
 J. Boyajian: Real-Time Color Doppler Radar Display, Bull. Am. 
 , - 4HE DETERMINATION OF THE DIELECTRIC PROPERTIES OF EARTH MATERIALS REMAINS LARGELY EXPER 
 OVAL CASE CAN ALSO REQUIRE A VERY HIGH ALTITUDE FOR THE SITE LOCATED IN THE OVAL NOT UNDER SURVEILLANCESO HIGH THAT THE SITE MUST OFTEN BECOME AIRBORNE &INALLY  THE TRANSMIT ANTENNA WILL BE IN DIRECT ,/3 OF THE RECEIVE ANTENNA WHEN  , a  R 4   R2 WITH HT     SO THAT  AGAIN WITH ALL UNITS IN KILOMETERS   , a  H4   H2    #ASE , !REA OF ONE OVAL  22MAX  ON 2X OVAL 22MIN  ON 2X OVAL  #IRCLE "ENCHMARK   O 2-2- 2- /NE /VAL  2-^O ;2-  
 Navy shipborne AN/SPS-48, and the Series 320 radars are all examples of S-band 3D surveillance radars con- sisting of a small stack of frequency-scanned beams which are then step-scanned as a group to cover the elevation surveillance volume.20'21 The use of frequency-scanning beams in elevation as a height finding tech- nique is a form of the general technique of sequential lobing, in which amplitudes from adjacent sequentially formed beams are compared to estimate the target el- evation angle. The elevation-angle accuracy achievable in this class of radars is not as good as that of stacked-beam or phase-scanned monopulse radars, e.g., radars employing simultaneous lobing. There are several fundamental reasons for this. 
 SHOULDER GEOMETRY  THE RECEIVER MIGHT USE A SET OF BEAMS TO  COVER THE NORTH SIDE OF THE BASELINE THEN  AS THE TRANSMIT BEAM SCANS PAST THE RECEIVER  IT SWITCHES THE SET TO THE SOUTH SIDE  THUS HALVING THE TOTAL NUMBER REQUIRED 4HE  "ISTATIC  !LERTING AND #UEING  TEST PROGRAM USED TIME 
 Thus the  MTI radar must operate at long wavelengths (low frequencies) or with high pulse repet~tion  frequencies, or both. Unfortunately, there are usually constraints other than blind speeds  which determine the wavelength and the pulse repetition frequency. Therefore blind speeds  might not be easy to avoid. 
 779–791; vol. III, chap. 14. 
 BASED ALTIMETERS  CAN BE GROUPED INTO FOUR BROAD CATEGORIES LARGE 
 An offset, or ojfcenter,  PPI has the zero position of the time base at a position other than at the center of the display to  provide the equivalent of a larger display for a selected portion or the service area. A delayed PP/ is  one in which the initiation of the time base is delayed.  R-scope. 
 TIONAL FILTERS AROUND ZERO DOPPLER  BUT THESE WOULD NOT MEET THE DESIGN CONSTRAINTS DISCUSSED ABOVE 4HE MAIN BENEFIT OF A CUSTOMIZED DOPPLER FILTER BANK DESIGN  AS &)'52%  4HIRD &)2 FILTER IN DOPPLER FILTER BANK DESIGN             
 9.29). Asthe waveguide feed horn ismoved from top tobottom, the beavertail beam scans from minimum elevation angle tomaximum. The m.-: ~-y---- . 
 VENTIONAL SINGLE 
 FIG. 18.16 AGC in monopulse tracking. In a three-channel monopulse radar, all three channels are controlled by the AGC voltage, which effectively performs a division by the magnitude of the sumIF AMPLIFIER DETECTOR AGC VOLTAGE ANGLE ERRORDETECTOR IF AMPLIFIERAGCAMPLIFIER . 
 SEC. 3.9] ACTUAL COMPLEX TARGETS 77 and can bedescribed better asaseries offlashes. The power inthe higher harmonics decreases only slowly with increasing harmonic number. 
 2.28. At the lower radar frequencies the transmission line  introduces little loss, utlless its length is exceptionally long. At the higher radar frequencies,  attenuation may not always be small and may have to be taken into account. 
 This isone reason forthe use oflarge antennas. Another advantage oflarge antennas, having todowith theresolution oftheradar set, isthat the beamwidth varies inversely asthelinear dimension ofthe antenna. Mathematically thebeamwidth e(degrees) isusually related tothewidth Doftheantenna and thewavelength 1oftheradiation by theapproximate formula (1) ifDand Xaremeasured inthe same units. 
   AND GSSTRACK A M4 6ARY RA TO INCREASE  DECREASE GAINS  AND OBTAIN DESIRED  PERFORMANCE USING EQUATIONS IN 4ABLE 2ESPONDS VERY WELL TO MANEUVERS  BUT OPERATES AT THE EDGE OF FILTER STABILITY (IGHER RADAR MEASUREMENT RATE CAN ACTUALLY RESULT IN LESS ACCURATE TRACK  -ODEL NO  2ANDOM CHANGE IN VELOCITY AT EACH MEASUREMENT INTERVAL SV BAA 
 In tcr111s of numbers of operational radars, frequency scanning has probably seen  more application than any other electronic scanning method. The first major electronically  scanned phased arrays that performed beam steering without frequency scan employed the  I lug.gins phase shifter (Sec. 8.4) which. 
 Theheightfindercanalsobemadetoprovide goodrange resolution fortargetcounting byutilizing anarrower pulsethanmightbedesiredfora long-range 20air-surveillance radaroperating atalowerfrequency. Thustherearemanyreasonsforthenodding-beam heightfinderbeingagoodchoicefor obtaining thethirdcoordinate onaircraft. Insteadofmechanically rockingtheentireantenna structure, thehorizontal fanbeamofa heightfindercanbescanned inelevation byelectromechanical means,suchaswiththe Robinson scanner, organ-pipe scanner, ordelta-a(orEagle)scanner.Itisalsopossible toscan thebeamwithelectronic phaseshifters. 
 750–755, September 1978. 35. G. 
 9.5 OBJECTIVESANDTAXONOMYOFECCM TECHNIQUES The primary objective of ECCM techniques when applied to a radar system is to allow the accomplishment of the radar intended mission while countering the ef- fects of the enemy's ECM. In greater detail, the benefits of using ECCM tech- niques may be summarized as follows: (1) prevention of radar saturation, (2) en- hancement of the signal-to-jamming ratio, (3) discrimination of directional interference, (4) rejection of false targets, (5) maintenance of target tracks, (6) counteraction of ESM, and (7) radar system survivability.3 There are two broad classes of ECCM: (1) electronic techniques (Sees. 9.6-9.9) and (2) operational doctrines (Sec. 
 CALLY ON EACH TRANSMITTED PULSE 'ASEOUS RECEIVER 
 Jensen, L. C. Graham, L. 
 NOISE AMPLIFIER,/  LOCAL OSCILLATOR-&  MATCHED FILTER-273  MEDIUM 
 Nathanson, F. E.: "Radar Design Principles," McGraw-Hill Book Co., New York, 1969.  48. 
 I Ill I I I ( I KONI( A1 I Y Slf~l~KI:l) I'IIAS1:I) AKKAY ANIFNNA IN KA1)AR 281  The first factor is a sine wave of frequency w with a phase shift (N - l)rC//2 (if the phase  reference were taken at the center of the array, the phase shift would be zero), while the second  terrll represents ;~ri :iniplil uclc f:ictor of the form sin (N$/2)/sin ($12). The field in tensity pat-  tern is the r~iagriit~~tle of IJq. (X.2), or  -ilie plttterri 11;1s ri~~lls (~croc) wlien the ~~urilerator is zero. 
 65, pp. 1470-1504, October, 1977.  131. 
                       
 A second PBR, called the HDTV-Based Passive Radar ,51 exploits a cooperative  high-definition TV transmitter for air surveillance in the co-site region. It uses range  multilateration from four receivers located within 10 km of the transmitter to track  low-flying aircraft and helicopters as a gap-filler for monostatic air surveillance  radars. Predicted detection and tracking ranges of 30 km on a 1 m2 target have been  demonstrated in real time with 2D tracking errors generally less than 50 m. 
 III is shown in ﬁgure 3.11. It was a high-pass ﬁlter, with a low frequency −3 dB cut-off of about 40 kc/s. It was reported that in moderate sea conditions the sea returns disappeared when the discriminator was switched on and in rough seas the returns became thinand scattered. 
 This is usually satisfactory forradar operation. Insome complex components, such asequation-solving circuits, and for synchro applications, fixed frequency isnecessary. Inthese cases itisoften desirable, particularly where thea-cloads areheavy, toobtain that part oftheload which can beallowed tovary infrequency from anengin~ alternator, using asmall inverter settoobtain thefixed-frequent ypower needed. 
 NRL/MR/5320-93-7181,  July 1993. ch20.indd   78 12/21/07   10:46:35 AMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 16. Jlidayel. M .. 
 LEVEL $"& IS THAT LESS DIGITAL DATA  WHICH MUST BE PROCESSED TO FORM THE RECEIVE BEAMS  IS PRODUCED THAN FOR ELEMENT 
 MODE TWO 
 TRACK RESOLUTION  AND CROSSRANGE RESOLUTION IS SOMETIMES CALLED  ALONG 
 (D.11a) in Willis.1 More terms in these series can be used if  greater accuracy is required.FIGURE 23.2  Normalized ovals of Cassini, lying in the bistatic plane, the plane containing  transmitter, receiver, and target2 (Courtesy SciTech Inc .)KEY: Tx =  Transmitter (left focus)  Rx =  Receiver (right focus) Tgt =  Target (lying on oval)  L  =  Baseline (Tx - to - Rx distance)  RM     =  Equivalent monostatic range   (benchmark case where L = 0)  RR(max)  =  Maximum Rx - to - Tgt range   permitted on oval*  RR(min)   =  Minimum Rx - to - Tgt range   available on oval**  RR(av) =  Radius of a circle with area   equal to area of one oval in   the two-oval case when L > 3RM  _______  * When the Tgt lies on the baseline  extended beyond the Tx ** When the Tgt lies on the baseline  extended beyond the Rxa. b. c. 
 NAL IS THEN PROCESSED USING A  PULSE COMPRESSION FILTER THAT CON SISTS OF A MATCHED FILTER  TO ACHIEVE MAXIMUM SIGNAL 
 causi~ig the phase shift of the beat signal to vary cyclically with time. The indicating  system was designed so that it did not respond to the 10-Hz modulation directly, but it caused  the fixed error to be averaged. Normal fluctuations in aircraft altitude due to uneven terrain,  waves on the water, or turbulent air can also average out the fixed error provided the time  coristant of the indicating device is large compared with the time between fluctuations. 
 pp. 427 463. March. 
 Some devices,  such as high power transmitters, cannot operate continuously and only gated noise  measurements are possible. The gated phase noise spectrum is the summation of the  CW phase noise spectrum replicas centered at frequencies ± nfR, where fR is the PRF  and n is an integer. The total gated phase noise in the PRF bandwidth fR equals the total  CW phase noise in the transmit pulse bandwidth. 
 TORS  AND THE TOLERANCES REQUIRED FOR SETTING THE PHASES ARE HIGH 4HIS TYPE IS NOT COMMONLY USED 0ARALLEL &EEDS  &IGURE  SHOWS A NUMBER OF PARALLEL 
 Right: Magic Tee.     Since both feed -ins (beam 1 and 2) are of the same phase and are coherent, a summation pa t- tern will be radiation, as represented in Figure 13.4.  . 
 Freeman and A. Currie, “Synthetic aperture radar (SAR) images of moving targets,” GEC J .  Res., vol. 
 FRIENDLY CODE THAT INCORPORATES A WIDE VARIETY OF SOFTWARE MODULES  SOME OF WHICH ARE BASED UPON LEGACY . 
 !NGLE 2ADAR ,AND #LUTTER -EASUREMENTS AND %MPIRICAL -ODELS  .ORWICH   .9 7ILLIAM !NDREW 0UBLISHING    2 % #LAPP  h! THEORETICAL AND EXPERIMENTAL STUDY OF RADAR GROUND RETURN v -)4 2ADIAT ,AB  2EPT   #AMBRIDGE  -!    4 3 'EORGE  h&LUCTUATIONS OF GROUND CLUTTER RETURN IN AIRBORNE RADAR EQUIPMENT v  0ROC )%%  ,ONDON   VOL   PP n    % ! 2EITZ ET AL  h2ADAR TERRAIN RETURN STUDY  FINAL REPORT -EASUREMENTS OF TERRAIN BACK 
 SITE REGION HAS TIME TO CAPTURE ALL PULSES FROM A MONOSTATIC RADAR THAT USES RANGE 
 PASS FILTER   SWELL COMPONENTS OFTEN TAKE THE  FORM OF LONG 
 BASED RADAR ALTIMETERS PRESENT AN ELEGANT EMBODI 
 f 11n. Note that when the denominator is zero, the  numerator is also zero. The value of the field intensity pattern is indeterminate when both the  denorniriator and nutlierator are zero. 
 T. Ransone, Jr., and J. A. 
 The airframe is covered with thin absorbing material whose edges  are serrated to reduce reflections where hatches and covers fit into the fuselage. B-2 Spirit Bomber.  Northrop, the prime contractor for the B-2 Spirit, faced the  same problem with engine placement that Lockheed did with the F-117 Nighthawk. 
 D. Albright: Airborne Pulse Doppler Radar, IRE Trans., vol. MIL- 5, pp. 
 Prats, P .; Scheiber, R.; Mittermayer, J.; Meta, A.; Moreira, A. Processing of sliding spotlight and TOPS SAR data using baseband azimuth scaling. IEEE T rans. 
 Over water the accuracies are slightly worse. The backscatter energy over  water, except for near vertical incidence, is generally less than over land, thus lowering the  signal-to-noise ratio. Also there is an apparent increase in the angle of depression since the  rapid variation of sea echo (a0) as a function of the depression angle y favors returns from  the lower half of the incident beam. 
 Such multibeam sys- . terns have found application in combination with mechanical rotation for 3D coverage. Multiple Independently Steered Beams. 
 13.9 ANGEL ECHOES  Radar echoes can be obtained from regions of the atmosphere where no apparent rellecting  sources seem to exist. These have been called by varioi~s names, but they are commonly called  gl~osts or nnyels. They can take several different forms and have been attributed to various  caiises. 
 66  The criterion of 10 mW /cm2 is based on the experimental observation that thermal effects  are dominant. However, there is evidence indicating that nonthermal biological effects also  occur from exposure to microwave radiation.68 Pulsed power can produce biological change  · not obtained with CW power of the same average value. Therefore, the possibility of dan­ gerous effects with excessively high peak ·powers should not be overlooked even if the average  power is less than the safe threshold. 
 BAND RADAR VOLUMETRIC DATA v )%%% 4RANS 'EOSCI 2EM 3ENS  VOL   PP n    * "RIDGES AND * &ELDMAN  h!N ATTENUATION REFLECTIVITY TECHNIQUE TO DETERMINE THE DROP SIZE  DISTRIBUTION OF WATER CLOUDS AND RAIN v * !PPL -ETEOROL  VOL   PP n    $ 3 :RNIC AND ! 2YZHKOV  h0OLARIMETRY FOR WEATHER SURVEILLANCE RADARS v  "ULL !MER -ETEORO  3OC  VOL   PP n     4 ! 3ELIGA AND 6 . "RINGI  h0OTENTIAL USE OF RADAR DIFFERENTIAL REFLECTIVITY MEASUREMENTS AT ORTHOGO 
 W. Ewell, M. M. 
 Further discussion of these systems can be found in [ 3]. The FAA was a particularly important user of ASV radar. During the course of the mid-Atlantic convoy battles in 1941 and 1942, when the convoys were out ofTable 8.1. 
  OR 6 
 F. Goodrich et al., “Diffraction and scattering by regular bodies—I: The sphere,” University of  Michigan, Dept. Electr. 
 Insteadoftheimpulseresponse, theresponse of atargettoarampfunction issometimes moreconvenient toworkwith,especially whenthe longerwavelengths areusedtoobtaintargetclassification. Themethodofinversescattering seemstorequireanexamination ofthetargetovera largefrequency range,perhapsasmuchas10to1.Hthephaseshiftaswellastheamplitude of theechoaremeasured, fewerfrequencies mightbeutilizedthanwhenamplitude aloneis obtained.s6Experiments withasmanyas12frequencies havebeencarriedoutforsimple scattering objects,butasfewasfourfrequencies weresaidtobeadequate forthediscrimina­ tionofobjectsascomplex asaircraft. S3 Automatic targetclassification. 
 BY 
 ING RAY 
  -ULTI 
 Modulators can be classed as either low power or  high power, depending on how the tube is modulated. If the tube has a grid, a small and relatively inexpensive type of modulator can be  used, but grids usually are not feasible with high power tubes. A widely used switching  element for low-power modulators is the MOSFET transistor.47 Low-power modulators can be used with tubes that employ a modulating anode,  as does the linear-beam amplifier. 
 The former phenomenon was quickly  exploited for the detection and location of surface ships and submarines. The latter effect was  not exploited initially, but was later used for airborne mapping radars.  Until the middle of 1940 the development of radar in Britain and the United States was  carried out independently of one another. 
 1977.  99. Casner. 
 ING RADAR RETURNS MAY BE DISPLAYED TO YIELD AN IMAGE OF THE GROUND !T A NONZERO SQUINT ANGLE  THE ISODOPS ARE NOT ORTHOGONAL TO THE RANGE CONTOURS HOWEVER  ADDI 
 ch03.indd   32 12/15/07   6:03:35 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 
 Instead,thecomprehensive termpaper,usuallyinvolving aradardesignproblem or astudyindepthofsomeparticular radartechnology, hasbeenfoundtobeabcttermeansfor havingthestudentreinforce whatiscovered inclassandinthetext.Evenmoreimportant, it allowsthestudenttoresearch theliterature andtobeabitmorecreative thanispossible by simplysolvingstandard problems. Abookofthistypewhichcoversawidevarietyoftopicscannotbewritteninisolation. It wouldnothavebeenpossiblewithoutthe manycontributions onradarthathaveappeared in theopenliterature andwhichhavebeenusedhereasthebasicsource·material. 
 The solid circles are the averages over a ± 20° sector around the broadside  aspect.92 The x's are the average of the ± 20° head-on and ± 20° tail-on aspects.92·93 (Note  that the values given for the pigeon in Fig. 13. JO differ from those given in Table 13.3. 
 The height baseline is Δz.Esstands for the amplitude information of the SAR image. Rsp2represents the distance from S 3to the target P . 138. 
 IRE, vol. 48, p. 1164, June, 1960. 
 32, pp. 419-422, July, 1944.  2. 
 MATING SURFACE WAVE RADAR PERFORMANCE 4HE SURFACE IS ASSUMED TO BE SMOOTH   TARGET AND ANTENNA HEIGHTS ARE  M  CONDUCTIVITY IS TAKEN AS  3M  AND THE DIELECTRIC CONSTANT IS . Óä°Ç{  2!$!2 (!.$"//+  3CATTERING 4ARGETS AND #LUTTER  4HE DISCUSSION OF (& 2#3 AND SEA CLUTTER IN  3ECTIONS  AND  APPLIES EQUALLY TO (&372 INDEED  THE ABSENCE OF THE COR 
 Twystron . The bandwidth of a conventional klystron is limited primarily by  the bandwidth of the output resonant cavity. If a coupled cavity slow-wave circuit,  as is used in the TWT, is substituted for the output resonant cavity of a klystron  (Figure 10.3 d), the bandwidth of the klystron can be increased significantly, and there  is a slight increase in efficiency. 
 The  effects of the entire atmosphere must be considered in such cases.13•14  12.5 ANOMALOUS PROPAGATION  A decrease in atmospheric index of refraction with increasing altitude, as described in the  previous section, bends the radar rays so as to extend the coverage beyond that expected with  a uniform atmosphere. If the gradient of the index of refraction is strong enough for the rays to . PROPAGATION OF RADAR WAVES 451  have the same curvature as the earth itse\r, it would be possible for initially horizontal rays to  bend around the surface of the earth. 
 Because of its periodic nature, the filter also rejects energy  in the vicinity of the pulse repetition frequency and its harmonics.  The video signal [Eq. (4.3)] received from a particular target at a range R0 is  (4.4)  where ¢0 = phase shift and k = amplitude of video signal. 
 An error ellipse and its corresponding eccentricity are calculated for  each target. If the eccentricity is less than some arbitrary threshold (e.g., 0.866 rela - tive), the minimum perpendicular distance is calculated for road segments inside the  3-sigma ellipse. As shown in the figure, the perpendicular intercept may not lie inside  the road segment and will be discarded. 
 COSINE SHAPE AND PHASE CHANGES BETWEEN ADJACENT SUBPULSES OF MULTIPLES OF  on 4HE COSINE WEIGHTING PROVIDES FASTER SPECTRUM ROLL 
 ¤ ¦¥³ µ´     (ERE THE  
 Figure reports the range (left column) and azimuth (right column). On the rows, the phase, the real part, and the spectrum of each reference function is presented. Figure 6reports the obtained focusing results for the simulated case. 
 The firing ofV,.charges C2sufficiently to cutoffthetube sothat thesecond pulse, which arrives 2~sec later, cannot trigger it. Thus three pulses occurring atO,2,and 6psec appear across resistance Rand pass tothe mixer tobecombined with the video and other signals. Other combinations oftime delay can, ofcourse, beused. 
 Itisclear from theforegoing that thewidth ofthereply arcisalways limited ineither onelink ortheother, whichever isthenarrower, and that itcan becontrolled byadjusting either transmitted power orreceiver gain. Where manual adjustment for good reception ofaparticular beacon istobeused, cutting down the transmitted power would be. 260 RADAR BEACONS [SEC. 
 L. Diamond  (eds.), MIT Lincoln Lab. Tech. 
 Wavelength (K): The wavelength or operating frequency must be selected so that energy is refracted by the ionosphere to illuminate the desired area of the earth. The spectrum of the emissions must be constrained not to interfere with other users. Since both the ionosphere and the HF-band occupancy distributions are time-varying parameters, adaptive radar management is required. 
 #!4#(%2  IS PART OF A MOBILE ANTI 
 They often operate in an extreme environment, such as on a buoy buffeted by  the sea. Racons are specified to meet an extended operational temperature range of  –40° to +70°C. Modern racons operate by detecting an incident pulse and then measur - ing its frequency and responding at the same frequency, thereby reducing the interfer - ence potential with other in-band radars. 
 124 CHAP. 5. C-W RADAR SYSTEMS 127 5,1 General Considerations. 
 Elcc. Engrs..  vol. 
 Alargepartoftheclutter energymayberemoved withabankoffixednarrowband filterscovering theexpected rangeof doppler frequencies. Thebandwidthof eachindividual filtermustbewideenoughtoaccept theenergycontained inthetargetechosignal.Thewidthofthefilterwilldependuponthetime ontarget,equipment fluctuations~ andothereffectswhichbroaden theecho-signal spectrum as discussed previously ..Eachofthedoppler filterscanhaveitsownindividually setthreshold whoselevelisdetermined bytheamountofnoiseorclutterwithinthefilter.Thiscanbedone. adaptively. 
 02&  2ANGE 
 MOVING TARGET CATEGORY USUALLY INCLUDES BOTH TARGETS AND BULLETS OR MISSILES&)'52%  4YPICAL '-4 WEAPON GUIDANCE ADAPTED COURTESY 3CI4ECH 0UBLISHING  &)'52%  #ARTOGRAPHIC 
 Squint Mode. In most examples of synthetic aperture radar, the beam is directed at right angles to the ground track of the aircraft. In some cases, however, it is desirable to "squint" the antenna beam so that an area either . 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars.  SPACE-BASED REMOTE SENSING RADARS  18.696x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 119. Y . 
 This drawback, and the elaborate calibration necessary atanoverland site, have ledtothedevelopment ofother height-finding means, even forlong- wave radar sets. SignalComparison.—A more rapid and convenient means ofheight- finding which isalso based ontheexistence ofmaxima and minima inthe elevation pattern ofalong-wave radar employing ground reflection is signal comparison. Two ormore antenna systems with different eleva- tion patterns areprovided atasingle radar station, and theintensity of the echo received onone antenna iscompared with that received on another. 
 8.4 Radar Interrogation vs.Special Interrogators 8,5 Independence ofInterrogation and Reply. 8.6 Frequency Considerations243 246 246 250 251 252 254 260 CODING ............ 263 8.7 Interrogation Codes ...... 
 TRAFFIC CONTROL RADAR 4YPICAL TIME 
 Saxton and H. G. Hopkins, “Some adverse influences of meteorological factors on marine  navigational radar,” Proc. 
 WAY RADAR PROPAGATIONn ,OW PROBABILITY OF  INTERCEPT ,0)  TECHNIQUES ARE APPLIED TO RADAR TO WIN THE BATTLE OF hTO SEE AND NOT TO BE SEENv SEE 3CHLEHER  AND REFERENCES THEREIN Ó{°{Ê 
 For small signals (A1. <£ s), the detector reduces to the square-law detector n VA1-V * T (8.3) and for large signals (A1 >$ s), it reduces to the linear detector n 2 AgX1 > T (8.4) For constant signal amplitude (i.e., A1 = A) these detectors were first studied by Marcum1 and were studied in succeeding years by numerous other people. De- tection curves for both linear and square-law detectors are given in Chap. 
 Clarke, “Monitoring techniques for phased-array antennas,” IEEE Trans .,   vol. AP-33, pp. 1313–1327, December 1985. 
 The doppler shift is a function of the transmitted frequency /0 and radial velocity VR [the component of velocity along the line of sight (LOS) from the source to the observer—either a receiver or a reflector]. /dop = Wc)VR where c = velocity of light. In the geometry of Fig. 
 It can be seen that the interferometric ArcSAR could acquire high-precision DEM image of the scenes. 147. Sensors 2019 ,19, 2921 (a) DEM image on the slant range                 ( b) DEM image on the ground range  Figure 20. 
 MTT-23, pp. 276-281, March, 1975.  18. 
 BEAM SCATTEROMETER THAT EMPLOYS DOPPLER FILTERING  THE GOVERNING EXPRESSION IS   +3.2 3.2 .4"0         WHERE . IS THE NUMBER OF  STATISTICALLY INDEPENDENT PULSES SUMMED INTO  EACH R   MEA 
 This property causes almost half of its impulse- response coefficients to be zero. Figure 25.16 a illustrates the coefficients of a typical  filter for this application. All of the odd-numbered coefficients, except for the one  in the center, are zero, so the filter is very efficient to implement, as the zero coeffi - cients don’t require multipliers. 
 8.12 Cell-averaging CFAR. The letter C indicates a comparison. (From Ref. 
 If this condition is not appli- cable to a particular ground target, the differential-scattering-cross-section con- cept has no meaning for that target. For example, a very-fine-resolution radar might be able to resolve a part of a car; the smooth surfaces on the car would not be properly represented by a°. On the other hand, a coarser radar might look at many cars in a large parking lot, and a valid a° for the parking lot could be de- termined. 
 p. 592.  Mctiraw-tjill Book Company, New York. 
 Nathanson, Radar Design Principles , New York: McGraw-Hill, 1969, Chap. 8. 16. 
 Thus there is a tremendous mismatch between the information  content of a radar and the information-handling capability of an operator. The function of the  radar display is to aid the operator to extract in an efficient manner the information contained  in the radar signal that is important to the task. The usual type of radar display is a cathode-  ray tube or its equivalent. 
 VELOCITY PRODUCT IN THIS EXPRES 
 47, pp. 82 1-828, May,  1959.  20. 
 61, Sept. 25, 1978.  62. 
 Images with rotate. ( a) Container Ship image with rotate. ( b) Oil Tanker image with rotate. 
 The result of the lag is a tracking error. The on-axis tracker accounts for this lag,  as well as for other factors that can contribute to tracking error, so as to keep the target being  tracked in the center of the beam or on the null axis of the difference pattern. On-axis tracking,  as compared with trackers with a target lag, improves the accuracy by reducing the coupling  between the azimuth and elevation angle-tracking channels, by minimizing the generation of  cross polarization and by reducing the effects of system nonlinearities. 
 S. Goodman, and R. M. 
 C. Hansen (ed.), Academic Press, New York, 1966, pp. 217-288. 
 prepared the ﬁgures and tables. Z.Z. and Y.L. 
 The algorithm exploits the strong spatial coherence between adjacent pulses for increasing the number of pulses processed in each coherent interval, thus enhancing the DBS ﬁnal resolution. A performance analysis was carried out by ﬁrst using simulated point targets, and then real WAS data. Results demonstrated that the proposed algorithm outperforms other methods adopted in DBS imaging. 
 Tyler: Thickness of Saturn's Rings Inferred from Voyager 1 Observations of Microwave Scatter, Science, vol. 113, pp. 396-398, January 1984. 
 All rights reserved. Tektronix products are cov ered by U.S. and foreign patents, issued and pending. 
 Since the carrier phase israndom from pulse topulse, theenvelope ofthe summa- tion ofallsuch components within the carrier pass band will vary from pulse topulse sothat cancellation will beimperfect. These difficulties can beavoided bythe balanced modulation ofacarrier amplifier driven byanisolated oscillator. Acommon procedure istouse parallel-grid modulation ofapush-pull amplifier stage. 
  
 Turning off the receiver during transmission  with a duplexer is not possible in a CW radar since the transmitter is operated continuously.  Isolation between transmitter and receiver might be obtained with a single antenna by using a }  hybrid junction, circulator, turnstile junction, or with separate polarizations. Separate  antennas for transmitting and receiving might also be used. 
 F. Lane. Jr.: The AN/APN-22 Radio Altimeter, IRE Trans., vol. 
 Ó£°£È  2!$!2 (!.$"//+  4HE OUTPUT FROM THE MODEL IS SHOWN IN &IGURE  AND &IGURE  &INITE 
 NOISE AMPLIFIERS  ,.!S  ESTABLISH THE SYSTEM NOISE FLOOR PRIOR TO THE RECEIVER INPUT 4HE NOISE FROM THE  ANTENNA IS USUALLY SET WELL ABOVE THE RECEIVER NOISE FLOOR SUCH THAT THE RECEIVER HAS ONLY A SMALL IMPACT ON OVERALL SYSTEM NOISE !GAIN  THE TRADE 
 If the beam is scanned rapidly enough, however, it will have the effect of seeing .. almost  simultaneously" in all directions. The scan rate of the beam must be greater than the radar  signal-bandwidth to preserve the information contained in the received signal. 
 45, pp. 674-675, July, 1977.  71. 
 34!4% 42!.3-)44%23   ££°£ FOR THE SWITCHING MODES IS DEFINED BY THE MANNER IN WHICH THE TRANSISTOR IS BIASED  AND HOW THE WAVESHAPE OF CURRENT AND VOLTAGE IS MANIPULATED &OR EXAMPLE  CURRENT SWING IN AN AMPLIFIER THAT IS BIASED #LASS 
 TRACK 
 A. D. Siggia and R. 
 Skolnik. M. I.: Nonuniform Arrays. 
 It can be obtained that BW1= BW2=BW3 and then the Doppler bandwidth of three beams is the same. Therefore, the three beam images have the same azimuth resolutions. The distance between ABis LAB=RStanθ (4) The distance between the BCand the distance between the ABare the same. 
 ON 
 Consequently, if the signals in storage are subjected to the same operations as those used in forming a physical linear array, one can get the effect of a long antenna aperture. This idea has resulted in the use of the term synthetic aperture to designate this technique. In the case of an airborne ground-mapping radar system, the antenna usually is mounted to be side-looking, and the motion of the aircraft carries the radiating element to each of the positions of the array. 
 For example, if the desired probability of detection were 0.95, a signal-to-  rloisc ratio of 6.2 dI3/l~ulsc is lieccssary il the target cross section were constant (case 5), b11t if  t he target cross section fluctuated with a Rayleigh distribution and were scan-to-scan uncor-  related (case 1). tlie signal-to-noise ratio would have to be 16.8 dB/pulse. This increase in  signal-to-noise corresponds to a reduction in range by a factor of 3.28. 
 W.: Automaticdetection Theory, chap. 15 of "Radar Handbook," M. I. 
 BEAM WAVEFRONT MAY INCUR PERFORMANCE PENALTIES 7HERE THE -&!2 IS PHASE STEERED  APERTURE FILL AND SIDELOBE STEERING EFFECTS CONSTRAIN USABLE APERTURE BANDWIDTH SIMILAR TO 3!2 LIMITATIONS 4HE LATTER IS BECAUSE THE ELEMENT PHASE ANGLES REQUIRED TO POINT THE MAIN BEAM ARE NOT THE SAME AS THOSE FOR THE OUTER SIDELOBES OF THE MODULATION USED  ,OW BANDWIDTH DATA LINKS CAN USE ALL THE RADAR BANDWIDTH TO IMPROVE ENCRYPTION  AND SIGNAL 
 TER RESPONSES SYMMETRICAL ABOUT ZERO  FREQUENCY #ORRECTION OF )& FILTER FREQUENCY  RESPONSE ERRORS WILL  IN GENERAL  REQUIRE ASYMMETRIC FREQUENCY CORRECTION THAT CAN ONLY BE PROVIDED AT BASEBAND USING COMPLEX COEFFICIENTS 4HE DEGREE TO WHICH THESE MULTIPLE RECEIVER CHANNELS MUST TRACK DEPENDS ON THE  SPECIFIC SYSTEM REQUIREMENTS !LTHOUGH MODERN SYSTEMS TYPICALLY INCLUDE SOME DEGREE OF CHANNEL EQUALIZATION FUNCTION  A REASONABLE DEGREE OF TRACKING BETWEEN GAIN  PHASE  AND TIMING MUST BE MAINTAINED IN ORDER TO ALLOW THE CHANNEL EQUALIZATION TO BE PERFORMED USING DIGITAL SIGNAL PROCESSING WITHOUT CONSUMING EXCESSIVE PROCESSING RESOURCES !LSO  THE RELATIVE STABILITY OF THE RADAR CHANNELS AS A FUNCTION OF TIME AND TEMPERATURE MUST BE SUCH THAT THE CORRECTIONS CAN MAINTAIN ADEQUATE TRACKING DURING THE TIME BETWEEN CALIBRATION INTERVALS $IGITAL BEAMFORMING SYSTEMS REQUIRE A LARGE NUMBER OF RECEIVER CHANNELS )N THESE  APPLICATIONS  SIZE  WEIGHT  POWER DISSIPATION  AND COST ARE CRITICAL CONSIDERATIONS È°£ÓÊ Ê * 
  6+     &)'52%   4RANSISTORS ARE THREE 
  CAN BE OBTAINED BY USING A  
 The same current flows  through both resistances. When a positive signal is  applied to the grid the cathode rises in voltage; mean- R  Output  Signal  Output  . “IMPOSSIBLE” CIRCUITS 97  while the anode goes negative—i.e., the anode output is  negative—and thus from the one cathode-follower it is  possible to get a positive and a negative output simul-  taneously. 
 Thereceivernoise-figure orsensitivity canalsobemeasured byuseofacalibrated signal generator. Withamatched resistance atthereceiver input,theoutputpowerisduetoreceiver noisealone.Thesignalgenerator poweristhenappliedtothereceiverinputandadjusted until thesignal-plus-noise powerisequaltotwicethereceiver noisepowerreadwiththematched resistance. Theinputsignalunderthiscondition issometimes saidtobetheminimum discern­ iblesignal.Itisalsoproportional to.thereceiver noise-figure. 
 SET MODE  THE DATA HAS TO BE CONVERTED TO THE CORRECT REFER 
 SION HARNESS  AND THE SLENDER METAL PYLON 4HE ECHO FROM A PLASTIC FOAM COLUMN ARISES FROM TWO MECHANISMS /NE IS A COHERENT SURFACE REFLECTION  AND  THE OTHER IS A NONCO 
 L.: Digital, Matrix, and Intermediate-Frequency Scanning, chap. 3 of" Microwave Scan-  ning Antennas, vol. Ill," R. 
 [IGARSS 2007] , IEEE, Barcelona, 2007. 178. M. 
 41.Horton. B.M.:Noise-Modulated Distance Measuring System,Proc.IRE,vol.47,pp.821-828, May. 1959. 
 INGv FILTER  WHICH MAY TAKE THE FORM OF A CONVENTIONAL MATCHED FILTER  HOWEVER  MAY COMPENSATE FOR THIS EFFECT  OR A MORE SOPHISTICATED FILTER SUCH AS 7IENER FILTER  WHICH RECOVERS THE ORIGINAL SHAPE OF THE WAVEFORM  APPLIED TO THE ANTENNA )T IS IMPORTANT TO APPRECIATE THE EFFECT OF THE MATERIAL IN CLOSE PROXIMITY TO THE  ANTENNA )N GENERAL THIS MATERIAL  WHICH IN MOST CASES WILL BE SOIL OR ROCKS OR INDEED ICE  CAN BE REGARDED AS A LOSSY DIELECTRIC AND BY ITS CONSEQUENT LOADING EFFECT CAN PLAY A SIGNIFICANT ROLE IN DETERMINING THE LOW FREQUENCY PERFORMANCE OF THE ANTENNA AND HENCE '02 4HE BEHAVIOR OF THE ANTENNA IS INTIMATELY LINKED WITH THE MATERIAL AND  IN THE CASE OF BOREHOLE RADARS  THE ANTENNA ACTUALLY RADIATES WITHIN A LOSSY DIELECTRIC   WHEREAS IN THE CASE OF THE '02 WORKING ABOVE THE SURFACE  THE ANTENNA WILL RADIATE  FROM AIR INTO A VERY SMALL SECTION OF AIR AND THEN INTO A LOSSY HALF SPACE FORMED BY THE MATERIAL 4HE BEHAVIOR OF ANTENNAS BOTH WITHIN LOSSY DIELECTRICS AND OVER LOSSY DIELECTRICS IS WELL REPORTED 4HE PROPAGATION OF ELECTROMAGNETIC PULSES IN A HOMOGE 
 END OR )& ATTENUATION IS OFTEN USED TO ADJUST THE GAIN OF THE RECEIVER TO COMPENSATE FOR RECEIVER GAIN VARIATIONS DUE TO COMPONENT VARIATIONS WHERE RECEIVER NOISE FIGURE DEGRADATION CANNOT BE TOLERATED È°ÇÊ  / 
 The 10-cm magnetrons that have been successfully tried for LITI arethetype 2,J32, thetype -LJ17, and thetype 70(;C’1”. :lt3cm, thetype 2J42 hasbeen used. JIost experience a~-ail:lble upto1940 has been with the 2,J32, lyith the 2J32 and ahard-tube mtxiulator, fre- quency modulation ~vithin apulse ne~er reaches anobjectionable !cvel. 
 The higher performance of  the superresolution techniques is often obtained at the expense of requiring a stricter  adherence to the assumed model; if the model is inaccurate, these techniques—which  rely on its heavy exploitation—subsequently become the most sensitive and more  prone to perform badly. For efficient superresolution, an array with a reasonable number of sub-arrays is  required; this may be the reason for the lack of application of this technique to practi - cal radar systems except for experimental purposes. Superresolution based on a small  ch24.indd   30 12/19/07   6:00:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Insteadofrequiring acommand foreachoftheelements ofthearray,thesubarray steering requires onlyp+qphaseshiftercommands perpointing angle,wherepisthenumber of elements inthesubarray andqisthenumber ofsubarrays inthearray.However, withq identical subarrays ofpelements each,thetolerance ontheindividual phaseshifters must usuallybebetterIhanwithasimilarconventional arrayofpqelements sincewithsubarrays , theerrorsacrosstheentireaperture arenolongerindependent. Ana)"radarslstemfunctions. Anarrayradarissometimes required toperform morethanone function withthesameequipment. 
 QUANTIZATION ERRORS 4HIS MAY BE DONE BY ADDING A CONSTANT PHASE SHIFT IN THE PATH TO EACH RADIATOR  WITH A VALUE THAT DIFFERS FROM RADIATOR TO RADIATOR BY AMOUNTS THAT ARE UNRELATED TO THE BIT SIZE &)'52%   %FFECTS OF PERIODIC AMPLITUDE AND PHASE MODULATION SIN P   SIN P o K S  .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°ÎÇ &)'52%   !PERTURE PHASE ERROR DUE TO PHASE QUANTIZATION   FROM -ILLER  &)'52%   0EAK SIDELOBES DUE TO PHASE QUANTIZATION . £Î°În  2!$!2 (!.$"//+  4HE VARIABLE PHASE SHIFTER IS THEN PROGRAMMED TO ACCOUNT FOR THIS ADDITIONAL INSER 
 Memo. Rept. 3322, July 1976. 
   4HUS  IN &IGURE p  WHERE  THE FIRST BLIND SPEED OCCURS AT ABOUT  66"     THE STAGGER RATIO IS e  ALTERNATING THE LONG AND SHORT PERIODS KEEPS THE TRANSMITTER DUTY CYCLE AS NEARLY CONSTANT AS POSSIBLE  AS WELL AS ENSURING GOOD RESPONSE AT THE FIRST NULL WHERE  6   6 "  &IGURES  AND  SHOW TWO OTHER  
  ",   -ANY PHASED ARRAY RADARS USE ANALOG BEAMFORMING )N AN ANALOG BEAMFORMER  THE RECEIVED SIGNALS FROM EACH ELEMENT  ARE COMBINED AT RADIO FREQUENCIES !T THE OUTPUT  OF THE ANALOG BEAMFORMER  CENTRALIZED RECEIVERS DOWNCONVERT THE SIGNAL FROM RADIO FREQUENCY 2&  TO AN INTERMEDIATE FREQUENCY )&  AND AN ANALOG 
 17.6. The Method ofIncremental Angle.-This section and thenext three will describe various specific methods ofrelaying the scanner information, the basis ofclassification being the geometrical quantities used. Asstated inSec. 
 At frequencies above 3000 Me/see awaveguide output istobepreferred as small coaxial lines arc over and are unduly 10SSY. Power isextracted from the back ofthe cavity bymeans ofaslitwhich expands, usually with discontinuities, until itsdimensions correspond tothose ofthewave- guide (Figs. 109 and 10”10). 
 J. Frank and J. Ruze, “Beam steering increments for a phased array,” IEEE Trans. 
 Range Resolution Factor of the Ambiguity Function. This subsection con- siders the factor in the generalized ambiguity function, Eq. (21.25), that is respon- sible for range resolution. 
 F, pp. 92-93, April 1980. 8. 
 ABOUT THE EDITOR IN CHIEF Merrill I. Skolnik, known worldwide for his leadership in radar research and de- velopment, has been affiliated with the Johns Hopkins Radiation Laboratory, Sylvania, MIT Lincoln Laboratory, the Research Division of Electronic Commu- nications Inc., the Institute for Defense Analyses, and the U.S. Naval Research Laboratory. 
 DAY  FOR A PARTICULAR MONTH AND LEVEL OF SOLAR ACTIVITY     !  !!%      #    $       
 The stable-base stabilizer, asthe name indicates, provides complete stabilization oftheplatform upon which theantenna ismounted. This requires useofatwo-axis gyro transmitter toprovide alignment orerror information forboth roll and pitch axes. The gyro isusually mounted remotely from the antenna structure inthis type. 
 The accuracy of range tracking, however, is affected by the loss in signal but not by  the slope at the crossover point. Therefore, as a compromise between the requirements for  accurate range and angle tracking, a crossover nearer the peak of the beam is usually selected  rather than that indicated from Fig. 5.6. 
 V2' V1 V2r — — r -4- cF2 - y- - C21 - + C22 - Note that all the quantities must contain both phase and amplitude and that as the phases of V1, V2 are varied to scan the beam, the reflection coefficients (r,, F2) will vary. Although only two elements have been used in this example, the tech- nique is completely general. For a large array the reflection coefficient of the m/ith element is given by r = V c Y?± L mn / j *^mn,pq TT a\\pq V mn The general case is treated in more detail by Oliner and Malech.59 No restrictions need be placed on either the amplitude or the phase of the excitation at each el- ement. 
 The early V A-87 four-cavity S-band  klystron had a 20 MHz bandwidth and a gain of 61 dB when its four cavities were  synchronously tuned, but when stagger-tuned, its bandwidth was 77 MHz (2.8%) and  a gain of 44 dB.3 Theory shows that the bandwidth of a klystron can be significantly increased by  increasing its current and thus its power. A 10 MW peak power klystron, for example,  can have an 8% bandwidth as compared to a 200 kW tube, which might have a 2%  bandwidth, and a 1 kW tube having only a 0.5% bandwidth. High-power multicav - ity klystrons can be designed with bandwidths as large as 10 to 12%. 
 This explains why a CPI of n + 1 pulses is needed to implement  the SVC concept. For each primitive detection in a CPI, calculate the set of all possible  target ranges out to the maximum instrumented range Rmax:  ˆˆ , ,,...,, max R r m R m mi i i = + ⋅ =PRI wher e0 1 2 PRI m R R ii max m ax , int( / ) , , = + = 1 1 2 3 (2.64) where RPRI,i is the ambiguous range interval corresponding to the ith CPI. After the  primitive detections from all CPIs in the processing dwell have been processed, the  values of ˆRi from all CPIs are sorted into a single list. 
 The major shortcoming of a digital approach is that its technology is restricted in bandwidths under 100 MHz. Frequency multi- plication combined with stretch processing would increase this bandwidth limita- tion. Digital matched filtering usually requires multiple overlapped processing units for extended range coverage. 
 These performance  enhancements are readily achieved by installing greater and more flexible signal and  data processing power. Severe Storm Warning.  One of the primary purposes of weather radars is to  provide timely warnings of severe weather phenomena such as tornadoes, damaging  winds, flash floods, and landfalling hurricanes. 
 Because there are no ground truths of ship features compared with refocused ships, we assume that the geometrical features of the ship are compact for a well-focused ship. The well-focused ships have smaller geometrical features than defocused ships. The geometrical features contain the length, width and the areas of ship. 
 Molochkov: " Proektirovanie Linzovykx, Skaniruyushchikx, Shirokodiapa-  zommykx Antenn i Fidernykx Ustroistv" (Design of Lenses, Scanning Antennas, Wideband  Antennas. and Transmission Lines.) Energiya, Moscow, 1973, pp. 81-82. 
 KT SOUTHERLY BLOWING WITH THE CURRENT %VEN WITH NO WIND  THE PRESENCE OF STRONG  CURRENT SHEARS CAN PRODUCE HIGHLY  AGITATED SURFACES 3HIPBOARD OBSERVERS HAVE REPORTED BANDS OF ROARING BREAKERS PASS 
 9 1. Shelton, J. P.: Multibeam Planar Arrays, Proc. 
 Neyman-Pearson observer. Thethreshold levelwasselected inChap.2soasnottoexceeda specified false-alarm probability; thatis,theprobability ofdetection wasmaximized forafixed probability offalsealarm.Thisisequivalent tofixingtheprobability ofatypeIerrorand minimizing thetypeIIerror.ItissimilartotheNeyman-Pearson testusedinstatistics fordetermining thevalidityofaspecified statistical hypothesis.24.2~ Therefore thistypeof threshold detector issometimes calledaNeyman-Pearson Observer. Instatistical termsitis claimed tobeauniformly mostpowerful testandisanoptimum one,nomatterwhatthea prioriprobabilities ofsignalandnoise.25TheNeyman-Pearson criterion iswellsuitedfor radarapplication andisusuallyusedinpractice, whether knowingly ornot.. 
 Hennings, “A theory of the imaging mechanism of underwater bottom topography  by real and synthetic aperture radar,” J. Geophys. Res ., vol. 
 The modulation frequency isnext chosen togive aconvenient range ofbeat frequenciesf~, subject totherestriction that thetime ofamodulat- ing cycle shall belong compared tothe maximum signal transit time. Avalue of120cpswas picked. This gives ~a=8000 cpsatanaltitude of 400 ft. 
 Ground- based radars used for severe storm research and warnings normally use S-band   (∼3 GHz) or C-band ( ∼5.5 GHz) transmitters. Airborne weather avoidance and precip - itation radars primarily use X band ( ∼10 GHz) due to size limitations and occasionally  C-band transmitters to minimize attenuation. Airborne and ground cloud radars and  spaceborne radars encompass the mm-wavelengths at Ku band (~15 GHz), Ka band  (~35 GHz), and W band (~94 GHz). 
 ÓÈ°ÓÓ  2!$!2 (!.$"//+  &)'52%   !2%03 COMPUTATIONS DISPLAY UPON THE #OMPOSABLE &ORCE.ET #/0.   4(% 02/0!'!4)/. &!#4/2  &0  ). 4(% 2!$!2 %15!4)/.   ÓÈ°ÓÎ ÓÈ°nÊ , 
 A. G. Kurashov (ed.), Shortwave Antennas,  2 Ed., in Russian, Radio i svyaz, January 1985. 
 105, Rudar- Prcsrtit  and Futrtrr, London, Oct. 23-25, 1973, pp. 239-244. 
 RADAR TRANSMITTERS 207  QKW-1723 TWTs. each with a peak power of 175 kW and an average power of 10.5 kW  operating over the frequency band offrom ll7Sto .1375 MHz. Since this radar is designed to  monitor ballistic-missile reentry vehicles, its pulse width is as great as 2000 µs. 
 Maksimov, et al., Radar Anti-Jamming Techniques , Norwood, MA: Artech House, Inc.,  1979. (Translated from Russian, Zaschita at Radiopomekh, Soviet Radio, 1976.) 22. D. 
 SENSING MECHANISM THAT FORMS AN ERROR PROPORTIONAL TO THE ANGLE BETWEEN THE TARGET AND THE ANTENNAS BORESIGHT ON EACH RETURN PULSE 4HIS IS ACCOMPLISHED BY COMPARING SIGNALS RECEIVED SIMULTANEOUSLY IN TWO OR MORE ANTENNA BEAMS  AS DISTINGUISHED FROM TECHNIQUES SUCH AS LOBE SWITCHING OR CONICAL SCANNING  IN WHICH ANGLE INFORMATION REQUIRES MULTIPLE PULSES %FFECTIVE MONOPULSE JAMMING TECHNIQUES GENERALLY ATTEMPT TO EXPLOIT THE MON 
   NO   !PRIL   * 4IERNEY  # - 2ADAR  AND " 'OLD  h! DIGITAL FREQUENCY SYNTHESIZER v  )%%% 4RANS !5 
 This data is used to add to or subtract from the angle shaft position data for real-time correc- tion of tracking lag. There are a large variety of tracking-radar systems, including some that achieve simultaneously both surveillance and tracking functions. A widely used type of tracking radar and the one to be discussed in detail in this chapter is a ground-based system consisting of a pencil-beam antenna mounted on a rotatable platform which is caused by motor drive of its azimuth and elevation position to follow a target (Fig. 
 92–99, April 1952.  3. F. 
 1259–1267, 1986. ch19.indd   48 12/20/07   5:39:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
    PP n  *ANUARY   0 7 (ANNAN  h-ICROWAVE ANTENNAS DERIVED FROM THE CASSEGRAIN TELESCOPE v  )2% 4RANS   VOL !0 
 Atmuch N FIG.31S.-Coastal areas ofKyushu andShikoku inthevicinity ofUwajima, Japan. Wavelength =3.2cm,3°beam, altitude 10,000 ft,radius 24nautical mi. 33”03’N. 
 $ NETWORK 4HE #OLLABORATIVE  !DAPTIVE 3ENSING OF THE !TMOSPHERE #!3!  RADAR NETWORK WILL INCLUDE MANY INEXPENSIVE   LOW POWER  SCAN 
 The line-oj-sight method isone which maintains theaxis ofthe beam ofradiation inahorizontal position orafixed angular distance above or below thehorizon asthe antenna rotates, scanning thehorizon. This is done byautomatically tilting theantenna about anaxis perpendicular to theplane ofthebeam and parallel tothefloor oftheaircraft. Figure 9.35 shows thestabilizing attachment, A>-/.~\.15,5, mounted forphotographic test onthescanner oftheA>”/.iPS-2 circular-scanning radar. 
 '~. r,i i. I : • 'l .. 
 TION LOSS FROM RADAR SYSTEM PARAMETERS SUCH AS FREQUENCY  PULSE LENGTH  ETC 4HE MODELS TO DO THIS CALCULATION ARE TAKEN FROM "LAKE  AND ARE FULLY DESCRIBED WITHIN THE !2%03  ONLINE HELP AND THE !2%03 OPERATORS MANUAL 4HUS  !2%03 RADAR SYSTEM ASSESSMENT MODEL WILL NOT BE REPEATED HERE 4HE INTENT OF THIS SECTION IS TO SHOW THE NECESSARY RADAR SYSTEM AND RADAR TARGET INPUTS NEEDED BY THE !2%03 PROGRAM 4HESE INPUTS ARE SHOWN IN &IGURES  AND  &OR A COMPLETE DESCRIPTION OF EACH INPUT PARAMETER  YOU MAY REFER TO THE !2%03 ONLINE HELP OR THE !2%03 OPERATORS MANUAL&)'52%   !2%03 COMPUTATIONS DISPLAY WITHIN 3)-$)3 SHOWING RADAR PROBABILITY OF DETECTION OF A  SMALL TARGET UNDER THE INFLUENCE OF TERRAIN 
 InSec.10.2itwas shownthatthefrequency-response function ofthematched filterwasgiven,exceptforit constant andatimedelay,by S*(J)H(J)=---------- 1Nj(J) 12 (11.11) whereinthenotation ofSec.10.2,S*(J)isthecomplex conjugate oftheFouriertransform of theinputsignalintheabsence ofnoiseandNlf)isthespectrum oftheinputnoise(the Fourier transform oftheinputnoisevoltage). Therefore, ifthemultiplier ofFig.11.2is preceded byamatched filter,theformoftheoptimum gatingsignalwillhe (11.12) ThisistheFouriertransform ofthedoubletimpulse 112(t),orfirstderivative oftheimpulse functionJ'(t).Thegatingwaveform istherefore (11.13) Theaboveanalysis indicates thatoptimum rangeprocessing consists inpassingtheecho signalthrough amatched filterfollowed byagatingintimethatsamples thesignalwaveform attheinstantbeforeandtheinstantfollowing thetimeTR•Thedifference between thesetwo samples isameasure ofthedifference between theestimated delaytimeTilandthetruedelay timeTo.Insomerespects, thegatingprocessisanalogous tothesplit-range-gate technique for range-tracking radarsdescribed inSec.5.6,exceptthatthesampling gatesdescribed hereare ofinfinitesimal widthwhereas theyareusuallyoftheorderofapulsewidthinrangetracking. Substituting theoptimum gatingsignalintotheexpression foraccuracy gives(Ref.3, Eq.12) JT~= 00 --~--- "'- 4I(2nJ)2IS(JW/IN j(J)12ilJ o(11.14) Ifthenoisespectrum isaconstant withspectralenergyequaltoNowatts/Hz ofbandwidth, themeansquareerroris 2 No(JTR)=-00------- 4f(2nJ)21S(J) 12dJ o Aneffective bandwidthpmaybedefinedsuchthat 00f(2nJ)2IS(J)12dJ <XJ p2= - 0000 =kf(2nJ)21S(J)12dffIs(!)12dJI -00 -00(11.15) (11.16) whereEisthesignalenergy.Thisdefinition ofbandwidth isunlikethosediscussed previously. 
 si(ta)=rect/parenleftbiggta Ts/3/parenrightbigg exp⎧ ⎪⎨ ⎪⎩j2πfdc(ta+tac,i) +jπedr(ta+tac,i)2 +jπe3rd(ta+tac,i)3⎫ ⎪⎬ ⎪⎭. (6) By performing the phase derivative of the upper formula and letting ta=0, the coefﬁcient of the ﬁrst-order phase can be obtained as (7). fd,i=fdc+edrtac,i+3 2e3rdt2 ac,i. 
 The  tops of the cells rniglit be at altitudes from 1 to 2 km. An individual cell might have a life of  from 15 to 30 riiini~tes. The cells can drift with tlie wind and align themselves in "streets."  Mucli of tllc ktiowlcdgc of tlic bclir~vior of convective cells lias been obtained from rildztr. 
 ENTRY  IS TO ADAPT THE TARGET MOTION MODEL FOR THE +ALMAN FILTER OVER TIME SO THAT MORE ACCURATE TRACKING OCCURS THAN WITH A SINGLE MODEL 4HE SIMPLEST FORM OF ADAPTATION IS A MANEUVER DETECTOR TO MONITOR THE TRACKING FILTER RESIDUALS DIFFERENCES BETWEEN MEASURED AND PREDICTED POSITION  ,ARGE  CORRELATED . 
 12 Tail-mounted ELDORA doppler weather radar  operated by the National Center for Atmospheric Research on  the Naval Research Laboratory P-3 research aircraft ( Courtesy  of University Corporation for Atmospheric Research © 2007 ,  Boulder, CO ) ch19.indd   38 12/20/07   5:39:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation.  THE PROPAGATION FACTOR, FP, IN THE RADAR EQUATION  26.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 angle with the surface equal  to that of the incident wave,  as shown in Figure 26.1. 
 However, atradarfrequencies thewavelength issmall. PROPAGATlON OF RADAR WAVES 457  cornpa1 cd with tlic cat tli's dinic~isions arid little energy is diffracted. I'llus radar coverage  cannot he extended nit~cli bcyo~id tlie li~ie of siglit by this niechatiism. 
 It can result from an error in the  aperture illumination and is generally undesired. In most antennas the first sidelobe appears  instead. The first sidelobe is smeared into a vestigial lobe as in Fig. 
 CATED RADAR DOPPLER NAVIGATORS 4HERE IS A THREE 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°xx FOUR POTENTIAL SOLUTIONS  WHICH PRESENTED AS DIRECTIONAL AMBIGUITIES 3PACE 
 15.13 MTI improvement factor as a function of the rms velocity spread of clutter for a two-pulse binomial-weight canceler. shown in these figures for rain and chaff is based on the assumption that the av- erage velocity of the rain and chaff has been compensated for so that the returns are centered in the canceler rejection notch. Unless such compensation is pro- vided, the MTI offer little or no improvement for rain and chaff. 
 R. Edison, R. K. 
 The hard work of preparing these chapters  was  done by the individual expert authors  of the various chapters. Thus the value of the Radar Handbook  is the result of the diligence and expertise of the authors who contributed their time, knowledge, and experience to make this handbook a useful addition to the desk of radarsystem engineers and all those people vital to the development, production, and employment of radar systems. I am deeply grateful to all the contributing authors for their fine work and the long hours they had to apply to their task. 
 Naturally, these latter filters were notnearly socritical astheoneat1000 cps. This concludes thediscussion ofthedesign and theleading difficulties ofasystem ofthis type. Performance was much asexpected. 
 1979.  130. I I~II~SCI~, R. 
 Cook and J. Paolillo, “A pulse compression predistortion function for efficient sidelobe  reduction in a high-power radar,” Proc. IEEE , pp. 
 SIGHT  SUCH THAT THEIR LOW CLOSING VELOCITY PLACES THEM IN SIDELOBE CLUT 
 DEPENDENT CONTOURS PROVIDE A SENSE OF BISTATIC RADAR PERFORMANCE  THEY DO NOT SHOW MAXIMUMMINIMUM DETECTION RANGES AND COVERAGE FOR VARIABLE BASE 
 TO 
 TAIN SUFFICIENT SPACING TO AVOID MECHANICAL DAMAGE TO THE ANTENNA )T CAN  THEREFORE  BE APPRECIATED THAT THE EFFECT OF CHANGES IN DISTANCE BETWEEN THE ANTENNA AND HALF SPACE IS TO CAUSE SIGNIFICANT VARIATION IN THE RESULTANT RADIATION PATTERNS IN THE DIELECTRIC ! PARTICULARLY USEFUL ANTENNA CAPABLE OF SUPPORTING A FORWARD TRAVELING 4%- WAVE  IS THE 4%- HORN )N GENERAL  SUCH ANTENNAS CONSIST OF A PAIR OF CONDUCTORS EITHER  0OWER 0OWER 0LANE2ADIATION PATTERN IN DIELECTRIC X DIRECTION  2ADIATION PATTERN IN DIELECTRIC Y DIRECTION  ( AHCOS COS COSP PPA AD ¤ ¦¥³ µ´ AHH HCOS COS COSP PPD AD ¤ ¦¥³ µ´  % AHCOS COS COS COSPP PPAD AD ¤ ¦¥³ µ´ AHH HCOS COS COS COSPP PPAD AD ¤ ¦¥³ µ´4!",%  0OWER $ENSITY 0ATTERNS IN !IR AND $IELECTRIC. 
 ELEMENT ARRAY   BITS IN A  
 Math ., vol. 4, pp. 361–378, 1951. 
 Conﬂicts of Interest: The authors declare no conﬂict of interest. References 1. Monserrat, O.; Crosetto, M.; Luzi, G. 
 However, in those  doppler regions free of sidelobe clutter, as shown in Figure 4.3 and Figure 4.4, target  detectability is limited only by thermal noise, independent of radar altitude, speed,  and sidelobe level. This requires system stability sidebands to be well below noise for  the worst-case main-beam clutter. Thus, although medium PRF provides all-aspect  target coverage, the target is potentially competing with sidelobe clutter at all aspects,  whereas with high PRF, a target can become clear of sidelobe clutter at aspect angles  forward of the beam aspect. 
 SCALE DYNAMIC SURFACE TOPOGRAPHY ARE CHARACTERIZED BY ABSOLUTE SEA 
 The permis - sible frequency selection is set between 5 and 28 MHz, and antenna radiation is not  considered below an elevation angle of 1 °. The analyses were made for a radar off  the mid-Atlantic coast of the United States and should be a good approximation for  any location where transmission paths are through the middle magnetic latitudes.  FIGURE 20.31  A specific example of SNR and clutter-to-noise ratio (CNR)  as determined by using Figure 20.30. 
 FREE DYNAMIC RANGE 3&$2  WHEN THE INPUT ANALOG SIGNAL IS TOO HIGH  AS WOULD BE THE CASE IF IT WERE PRESENTED WITH THE 2& OR HIGH 
 Requires helix- voltage-control range of 400 to 1500 V.± 10 to ±100ppm ± 1 to ±10ppm ±1% ±0.2% ±0.2%±0.5 ± 1 ±2 ± 1 ±0.3*± 15 ± 0.25 ± 2 ± 50 ± 20Up to 50 MHz 100 kHz to 300 MHz 60 to 2500 MHz 100 to 10,000 MHz 2 to 18 GHzLC oscillator Crystal oscillator Three-terminal gallium arsenide oscillator Voltage-tunable magnetron Backward-wave oscillator . Os and Is or +Is and -Is, in the phase code, as shown in Fig. 10.8. 
 C., and G. Hyde: Studies of the Focal-Region ofa Spherical Reflector: Gcomdric Optics,  IEEE Trans., vol. AP-16, pp. 
 75-549, July 1975. 51. Jones, R. 
 %23 
 . BOOK LIST  APPLETON, E. V., and BurmLper, G.: “ Wireless Echoes of  Short Delay,” in Proceedings of the Physical Soctety,  1932. 
 SURFACE DEVELOPMENT  AND DISCREPANCIES BETWEEN THE TWO DATA SETS FOR COMMON WIND SPEEDS HAVE WEAKENED THE EVIDENCE FOR SATURATION   /THER INVESTIGATORS DENY THAT IT IS EVEN POSSIBLE TO EXPRESS WIND DEPENDENCE IN THE FORM OF A POWER LAW  PROPOSING THE EXISTENCE OF A KIND OF THRESHOLD WIND SPEED  BELOW WHICH CLUTTER VIRTUALLY VANISHES AND ABOVE WHICH THE CLUTTER LEVEL RISES RAPIDLY TOWARD A SATURATION VALUE  4HIS IS INDICATED BY THE CURVES IN &IGURE   WHERE  THE STRAIGHT LINES CORRESPOND TO VARIOUS POWER LAWS AND THE CURVED LINES DERIVE FROM &)'52%   &REQUENCY DEPENDENCE OF SEA CLUTTER FOR WIND  SPEEDS OF ABOUT  KT  '(Z  &EINDT  '(Z  3CHROEDER  AND  '(Z  -ASUKO . 
 Glegg. K. C. 
 However, it is possible to change the effective phase center of a rcllcctor  antenna by employing two feeds to produce two squinted overlapping beams, as in an  amplitude-comparison monopulse radar (Sec. 5.4). The outputs of the two feeds are combined  using a hybrid junction to produce a sum pattern I: and a difference pattern L\. 
 The spec- trum of Fig. 19.3 will be broadened by noise, so that noise sidebands of feedthrough and clutter will appear at the target doppler frequency. In view of the magnitude of feedthrough and clutter, very low noise is required to prevent performance degrada- tion (masking of the target). 
 For v=300 mph and O,=~.radian, asbefore, wegetAU=~mph, showing that thefluctuations arenegligible when theantenna ispointing straight ahead. When thesystem iscarried inanairplane there isaneffect due tothe depression angle aswell asthe azimuth effect just discussed, Since the beam isusually broad inavertical plane, therange ofdepression angles within the illuminated area ofclutter islimited bythe pulse ~vidth. Under these conditions thespread inradial velocity isgiven by wsins dcosO ‘L’=mfor@<<90°, Cos~ where risthepulse length (infeet), hthealtitude, @thedepression angle, and Othe azimuth. 
 Originally, these techniques were developed for airborne microwave radars, but they  have been shown to have wide applicability in HF radar.135–138 The primary domain  where major performance gains are realized is spatial analysis, that is, beamforming.  In this context, a “snapshot” of the outputs from the all the receivers across the array  is taken and used to compute a set of complex-valued weights for each desired beam  direction; these are then applied to the receiver outputs before summing to form the  adapted beams. The reason for the efficacy of adaptivity here is that, as remarked  previously, HF radars are almost always external noise–limited. 
 SPONDING CROSS SECTION ESTIMATES A POWERFUL DISCRIMINANT FOR DISTINGUISHING BETWEEN SLOW 
 RATE BUDGET WAS THE NUMBER OF  BITS RETAINED FOR EACH SAMPLE IN THE RAW 3!2 DATASTREAM 7ORKING BACK THROUGH THE $3. CONSTRAINT  IT TURNED OUT THAT THERE WERE ONLY TWO BITS AVAILABLE FOR  -AGELLANS  RAW 3!2 DATA 9ESA  
 MATCHING ALGO 
 2.37,  If fr v=−×  = 202 5 101325200 33log. .log. γλ σλr r v ( )γ σ−  1 (2.39) where l is the wavelength, fr is the average pulse repetition frequency, and sv is the  rms velocity spread of scattering elements. 
 KT WIND SPEED AND A RAIN RATE OF  MMH 4HE SHARP DECREASE IN CORRELATION TIME IN THE PRESENCE OF RAIN REFLECTS THE BROADENING OF THE CLUTTER SPECTRUM  ALTHOUGH GENERALLY THERE APPEARS TO BE LITTLE QUANTITATIVE INFORMATION ABOUT THE EFFECT OF RAIN ON THE SPECTRUM OF SEA CLUTTER &)'52%   %FFECT OF RAIN ON THE CORRELATION FUNCTION OF WIND 
 ( c) Areas of ships. The defocused ships detected in two Gaofeng-3 SAR images are illustrated in Figure 10. The two ships are numbered as ship03 and ship04, respectively. 
 WIDTH SEPTUMLESS REGION  AS ILLUSTRATED IN &IGURE  !T THE SEPTUM  THE DOUBLE 
 (ILL  "OOK #OMPANY    PP n  n. £Ó°{Ó  2!$!2 (!.$"//+   9 4 ,O AND 3 7 ,EE EDS    !NTENNA (ANDBOOK 4HEORY  !PPLICATIONS AND $ESIGN  2EFLECTOR  !NTENNAS  #HAPTER   .EW 9ORK 6AN .OSTRAND 2EINHOLD #O )NC    # * 3LETTEN  h4HE THEORY OF REFLECTOR ANTENNAS v !IR &ORCE #AMBRIDGE 2ES ,AB  !, 
 In real cases, a noisy appearance of the two signals is expected (see Figure 3); for this reason, instead of using the two so extracted reference functions in the focusing procedure, the unwrapped phases of such functions were extracted to deﬁne their clean versions and reduce the noise effects on the focused image. Starting from the extreme points of such estimated phase functions a LMS polynomial ﬁtting was used to construct a clean version of the phase histories to be used in the description of the two reference 92. Sensors 2019 ,19, 1649 functions, both in azimuth and in range. 
 I.45  Index terms  Links   Seasat       22.15  signal processing in 21.17  signal-to-noise ratio in 21.15  spotlight mode 21.21  squint mode 21.20  target motion, effect of 21.21  three-dimensional spectrum in 21.21  unfocused    21.5  System noise temperature 2.26  T  TACCAR       15.61  in AMTI      16.3 16.5  Target illumination in missile guidance 19.9  Target models (Swerling cases) 2.21  Target noise 18.34  Target resolution in automatic detection 8.21  Target suppression in CFAR 8.17  Taylor coefficients 10.33  Taylor weighting in pulse compression 10.30  Terrain-bounce ECM 9.27  Thinned arrays 7.26  3D radar definition of 20.6  height finding in 20.6  Time-frequency-coded waveforms 10.26  Time gating in pulse doppler radar 17.19  Tornado detection 23.19  Track initiation 8.32  Track via missile 19.20  Track while scan 8.23  This page has been reformatted by Knovel to provide easier navigation. I.46  Index terms  Links   Tracking:  Automatic, in surveillance radar 8.23  with multiple radars 8.40  in pulse doppler radar 17.25  Tracking filters 8.28  Tracking radar:  acquisition of targets with 18.26  AGC in:  and angle noise 18.42  for monopulse 18.16  amplitude-comparison monopulse 18.9  amplitude noise in 18.34  angle noise in 18.37 18.57  conical scan 18.3  Conopulse    18.21  crosstalk in 18.48  digital range tracker for 18.30  doppler scintillation in 18.45  early-late gate in 18.27  and ECCM     9.25  errors in:  external sources of 18.34  internal sources of 18.50  reduction of 18.54  summary of 18.53  glint in     18.37 18.57  monopulse    18.8  (See also Monopulse tracking radar)  multipath in 18.46 18.54  nth-time-around tracking 18.30  on-axis      18.33  range noise in 18.43 18.57  This page has been reformatted by Knovel to provide easier navigation. I.47  Index terms  Links   Tracking radar: (Continued)   range tracking in 18.27  receiver noise in 18.50  servosystems in 18.22  TRAKX        18.32  tropospheric propagation effects in 18.49  TRAKX        18.32  Transmission-line noise temperature 2.30  Transmit-receive modules:  for SBR      22.23  (See also Solid-state transmitters)  Transmitters 1.3 4.1  for active seekers 19.38  amplifier chain 4.9  amplifier tubes for 4.12  combining of devices in 4.22  crossed-field amplifiers (CFAs) in 4.12  crowbars for 4.40  and ECCM     9.16  for HF radar 24.4  high-voltage power supplies for 4.25 4.41  klystron     4.14 4.19  magnetron 4.5  modulator effects in 4.25  modulators for 4.29  and MT1 radar 4.25 4.30  noise degeneration in 4.30  oscillator versus amplifier for 4.9  power capabilities of 4.21  and pulse compression 4.27  regulators for 4.41 4.42  solid-state ( see solid-state transmitters)  This page has been reformatted by Knovel to provide easier navigation. 
 POWER MICROWAVE FILTER IF NECESSARY !LL 2& TUBES PRODUCE SOME IN 
 with a saturation vapor pressure appropriate to the temperature  or the sea surface. 34 The air several meters above the sea is not usually saturated so there will  be a gradual decrease in water vapor pressure from the surface value to the ambient value well  above the surface. The decrease in water vapor pressure is approximately logarithmic, which  contributes a logarithmic decreasing term to the index of refraction. 
 BASED RADAR AGAINST GROUND CLUTTER   THE RADAR HAS INTERCLUTTER VISIBILITYIT CAN SEE BETWEEN LARGE CLUTTER RETURNS ,INCOLN ,ABORATORY  IN ITS MOVING 
 L. Moffatt: Natural Resonances of Radar Targets via Prony's Method and  Target Discrimination, IEEE Trans., vol. AES-12, pp. 
 Similarly, the variation of Pfa as a function of V1 can be found from Eq. (2.18); it is a monotonic-decreasing function. The method of applying these concepts to the prediction of radar range con- sists of four steps: (1) decide on a value of false-alarm probability that is accept- able (the typical procedure for making this decision will be described); (2) for this value of Pf09 find the required value of threshold voltage Vn through Eq. 
 $  RADAR  AT  -ISSOULA  -ONTANA  MOUNTED ON  
 Inthe positive clamp this impedance isunfortunately rather large sothat this clamp isnot very ‘‘tight .“ The negative one, onthe LThewell-known Rossi coincidence circuit isanexample ofatriode clamp.. SEC. 13.9] ELECTRO.VIC ISWI TCHES 507 other hand, issatisfactory inthis respect. 
 Maine. Air-supported radomes haveanumberofdisadvantages. Theirlifeislimitedbyexposure toultraviolet light.surfaceerosion. 
 ART POWER OUTPUT DENSITY  AND EFFICIENCIES OF COMPOUND SEMICONDUCTORS FROM  THROUGH  '(Z 7IDE "ANDGAP 3EMICONDUCTORS  3INCE THE INCEPTION OF SOLID 
 However, the  maximum gain of the pattern resulting from the cosine distribution is 0.9 dB less than the gain  of a uniform distribution.  Table 7.1 lists some of the properties of the radiation patterns produced by various  aperture distributions.' The aperture distributions are those which can be readily expressed in  analytic form and for which the solution of the inverse Fourier transform of Eq. (7.10) can be  conveniently carried out. 
  WAS FLYING MISSIONS AROUND THE WORLD 4HE INFLUENCE OF *OHNSONS RADAR SIGNATURE SPECIALISTS IS EVIDENT IN &IGURE   4HE MOST REMARKABLE FEATURE OF THE 32 
 2.The conveying ofangular increments bythemodulator pulses. 3.The conveying ofangular increments bythe sinusoidally varied pulse. 4.The method ofphase-shifted pulses. 
 Leary, F.: Researching Microwave Health Hazards, Electronics, vol. 32, no. 7, pp. 
 W. H. Stiles, D. 
 tracked vehicles vs. scanning antennas), rate of measured loca - tion change (ventilator locations don’t change), and consistent trajectory (e.g., 60 mph  where there are no roads is improbable for a surface vehicle).94 In addition, vehicles of  interest may have relatively low radial velocities requiring endoclutter processing16 (i.e.,  far enough inside main-beam clutter that detection is limited for doppler only filtering). A processing block diagram for GMTI is shown in Figure 5.36. 
 In order to operate effectively, sidelobe canceler  channels must track very closely. Constant offsets in gain or phase do not degrade  sidelobe canceler performance, but small variations in phase and amplitude across  the bandwidth cause significant degradation. For example, achieving a cancellation  ratio of 40 dB requires a gain tracking of less than 0.1 dB across the receiver band - width. 
 456 THERECEIVING SYSTEM—RADAR RECEIVERS [SEC. 12.7 forthebeginning ofthepulse and toaccept asignal only from thelatter part. This requires accurate timing and becomes very difficult for short pulses. 
 5–29, September 2007. 53. D. 
   /CTOBER   ! % "ARRIOS  h!DVANCED 0ROPAGATION -ODEL !0-  #OMPUTER 3OFTWARE #ONFIGURATION )TEM  #3#)  v 3PACE AND .AVAL 7ARFARE 3YSTEMS #ENTER 4$   !UGUST   ( 6 (ITNEY  h(YBRID RAY OPTICS AND PARABOLIC EQUATION METHODS FOR RADAR PROPAGATION MODELING v  IN 2ADAR   )%% #ONF 0UB VOL   /CTOBER n    PP n  +EN #RAIG AND -IREILLE ,EVY  HTTPWWWSIGNALSCIENCECOM  3 7 -ARKUS  h! HYBRID &INITE $IFFERENCE 
 Ingerson, and W. C. Wong: Large Lateral Feed Displacements in a Parabolic  Reflector, IEEE Trans., vol. 
 BASED IONOSPHERIC 2& HEAT 
 and the process is repeated until the evidence is convincing enough to make a definite  conclusion.  The Sequential Observer fixes the probability of errors beforehand but allows the integra­ tion time (or the number of observations) to be a variable. Two threshold levels are established  with a gray region in between. 
 (/2):/. 2!$!2   Óä°{Ç NOISE AND CLUTTER ENERGY BEING SUPERIMPOSED ON THE WANTED RADAR ECHOES  EITHER ADDI 
 CATE WITH MULTIPLE BOARDS  THE SERIAL LINKS FROM EACH BOARD GO TO A HIGH 
 Itistherefore desirable toreduce thepulse power output aswell aspulse width iftube lifeistobemaintained at increased repetition rates. Pulse rates upto40,000 cps have been obtained atreduced power output. Hydrogen thyratrons inproduction arethe 3C45, 4C35, and 5C22, rated at25,250, and 1000 kwrespective y;they areshown inFig. 
 Thelattereffectwas notexploited initially, butwaslaterusedforairborne mapping radars. Unlilthemiddleof1940thedevelopment ofradarinBritainandtheUnitedStateswas carriedoutindependently ofoneanother. InSeptember ofthatyearaBritishtechnical mission visitedtheUnitedStatestoexchange information concerning theradardevelopments inthe twocountries. 
 SHIP MOVEMENT OR IS .   #)6), -!2).% 2!$!2   ÓÓ°Ó£ &)'52%   ! SHIPS RADAR DISPLAY #OURTESY OF .ORTHROP 'RUMMAN 3PERRY -ARINE "6  . ÓÓ°ÓÓ  2!$!2 (!.$"//+  GEOGRAPHICALLY FIXED 4HE DISTANCE AND BEARING OF ONE POINT TO ANOTHER ON THE DISPLAY CAN  BE DETERMINED  NORMALLY BY USE OF A SPECIFIC MENU ITEM AND APPROPRIATE CONTROL OF THE DISPLAY CURSOR 4HE ACTUAL IMPLEMENTATION OF %",S  62-S  AND OFFSET MEASUREMENTS IS OFTEN EFFECTED BY A COMMON GRAPHICAL TOOL  WHICH IS USED TO POSITION AND DRAG LINES AND CIRCLES ACROSS THE DISPLAY BY MEANS OF THE CURSOR -ANY MARINERS FIND THE USE OF SHIP 
 M RESOLUTION WITHIN THE LENGTH OF THE PRIMARY MISSION  THE $3. DATA 
 (ed.): "Radar Hand- book," 1st ed., McGraw-Hill Book Company, New York, 1970. 11. Simpson, T. 
  %3!     NA +U n  3ENTINEL 
 39Radar Jamming • The barrage jammer floods the radar with noise and therefore decreases  the SNR. • The radar knows it is being jammed. GROUND TARGET AIR  DEFENSE  RADAR ATTACK APPROACH STANDOFF  JAMMER RACETRACK  FLIGHT PATTERN. 
 Receiver Bandwidth and Pulse Energy.-In allthe expressions fornoise power there appears the width ofthe amplifier pass band, (B. Apart from certain technical limitations, this factor iscompletely atour disposal, and wemust now decide how itsvalue shall bechosen. TOdo this wemust forthefirst time inthis chapter admit that weareconcerned with thedetection ofpulses. 
 C.: Properties and Applications of Reflective-Array Devices, Proc. IEEE, vol. 64, pp. 
 D. E.: First-Order Theory and Analysis of MF/HF/VHF Scatter from the Sea. I £EE Trans .•  vol. 
 PHONE WAVE 
 Ahmed, “RADARSAT,” Proceedings of the  IEEE , vol. 79, pp. 839–849, 1991. 
 Using Eq. (23a),this condition can therefore bewritten as 37rs=—rO=2.4r0.4(24) That is,thesignal amplitude should be8dblarger than therms clutter fluctuation. Itisconvenient toexpress thevisibility condition interms oftherms clutter amplitude ROinstead ofthe rms fluctuation. 
 Three operators, each with ascope, ride with the cross arm asitturns. Arange operator is provided with anA-scope having amovable marker which hekeeps on the signal being tracked. His rotation ofthe range handwheel feeds range information toa“height converter,” acomputing mechanism employing athree-dimensional cam tocombine slant range and elevation angle insuch away that continuous target altitude information ispro- duced. 
 definedasthevelocityofpropagation infreespacetothatinthemedium inquestion. Atmicrowave frequencies. theindexofrefraction IIforairwhichcontains watervapor is11.12 ('1)O~'-N_77.6p 3.73x10\' II-1 - - ------y-+--yr--- wherep=barometric pressure,mbar (1mmHg=1.3332mbar) e=partialpressure ofwaterVapor,mbar T=absolute temperature, K,_ Theparameter N=(n-1)106isthe"scaled-up" indexofrefraction andiscalledreji'£lctit1it y. 
 As the beam  is scanned off broadside, sotne of the transmitter power can be diverted to the face adjacent to  the direction of scar1 to radiate energy in the same direction.lJ5 The broadening of the bean1  due to the foreshortening of the planar aperture is compensated by the cooperative use of the  adjacent planar aperture.  f'  Unequally spaced arrays.'36 '39 Most array antennas have equal spacings between adjacent  elements. Unequal spacings have sometimes been considered in order to obtain a given beam-  width with considerably fewer elements than an equally spaced array, or to approximate a  desired pattern without the need for an amplitude-tapered aperture illumination. 
 172 Squadron RAF, while the other aircraft (including HF127 ‘2-C’) belong to No. 407 Squadron RCAF [©IWM FLM 1995].Airborne Maritime Surveillance Radar, Volume 1 3-18. Maximum detection ranges of a correctly tuned radar against a fully-surfaced submarine (HMS H32 was used for the trials, a boat of 410 –500 tons displacement, with no gun deck) were reported to be about 20 miles with the submarine beam-on,but only about 5 miles when viewed end-on. 
 Being  derived from statistics, they provide no explicit information on real-time “‘weather.”  that is, irregularities, waves, and other dynamic processes, though measures of vari - ability may be provided. Many early models had their genesis in the large database of  recorded ionospheric soundings made during the International Geophysical Year of  1957–1958 and the International Year of the Quiet Sun of 1964–1965. These models,  ch20.indd   19 12/20/07   1:15:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 434 INTRODUCTION TO RADAR SYSTEMS  sophisticated than that of a conventional pulse radar. Although it may be more complex than  a conventional long-pulse radar, the equipment for a high-power pulse compression radar is  more practical than would be required of a short-pulse radar with the same pulse energy. The  time sidelobes accompanying the compressed pulse are objectionable since they can mask  desired targets or create false targets. 
 Acylinder standing perpendicular ona plane is also strongly visible formost directions ofapproach. Iftheproblem is, onthecontrary, toconstruct atarget with alow radar cross section for most directions ofapproach, such configurations must beavoided. Furthermore, toeliminate ordinary specular reflection, surfaces perpen- dicular tothe probable directions ofobservation must beeliminated. 
 The amount of energy contained within the remainder of  the pulse after the initial spike is usually small and is not as serious as spike leakage.  When a solid·state duplexer is used or when a solid-state limiter follows the TR switch,  there need be no initial spike and burnout is not determined by the pulse energy. Burnout due  to pulses without an initial spike, but greater than about 1 µs in duration, is determined  primarily by the peak power. 
 Thedeionization processcanbespeeded upbythe addition ofwatervapororahalogen. ThelifeofTRtubesfilledwithamixtureofanoblegas (argon)andagaswithhighelectron affinity(watervapor)islessthanthelifeoftubesfilled withanoblegasonly. Toensurereliableandrapidbreakdown oftheTRtubeuponapplication oftheRFpulse, anauxiliary sourceofelectrons issupplied tothetube.Thismaybeaccomplished witha ..keep-alive," whichisaweakd-cdischarge thatgenerates electrons whichdiffuseintotheTR wheretheyacttotriggerthebreakdown onceRFpowerisapplied.Thekeep-alive generates noisejustasanyothergas-discharge device.Theexcessnoisetemperature isgenerally less than50K.40. 
 SPACE MAXIMUM DETECTION CONTOUR BECOMES THE FAMILIAR OVAL OF #ASSINI  AGAIN      )N THE FIRST CASE  THE  TRANSMITTER ILLUMINATES THE TARGET OVE R THE RECEIVERS SHOULDER IN THE SECOND  CASE  THE RECEIVER  VIEWS THE TARGET OVER THE TRANSMITTERS SHOULDER.   ")34!4)# 2!$!2   ÓÎ°Ç WITH THE MONOSTATIC CAVEATS CITED ABOVE 4HUS  THIS OVAL OR OVALS  PROVIDES A   CONVENIENTBUT AT TIMES OVER 
 Va.pp.210214.IEEE Publication 75 CHO93X-1AES. IIX.Bass.F.G.•I.M.Fuks.A.I.KalmYkov.TE. Ostrovsky. 
 CODED SIGNAL ,ENGTH #ODE                    4!",%    +NOWN "INARY "ARKER #ODES. n°£n  2!$!2 (!.$"//+  A LENGTH  "ARKER CODE FOR ZERO DOPPLER SHIFT SUPERIMPOSED UPON ALL POSSIBLE AUTO 
 + #HAN ET AL  h%XPERIMENTAL STUDIES OF BISTATIC SCATTERING FROM TWO 
 FACTURED WITH SOLID 
 There will probably be anaverage loss1ofabout 3db, asinthe case ofauniform distribution, whether there are many blind speeds inthe interval Oto400 mph or whether thefirst optimum speed comes at,forexample, 400 mph. The choice ofblind speeds isofnoparticular consequence, per se;but there may bespecial cases, such asairport traffic control, where theradial speed can beregulated. Blind speeds can then bechosen accordingly. 
 There is no theoretical limit to the bandwidth of a Butler array except for the bandwidth  associated with the hardware making up the network, which can be greater than 30 percent.  They have even been constructed with bandwidths of several octaves.94 Operating over too  wide a band, however, changes the beamwidth, shifts the location of the beams, and can  introduce grating lobes just as with any other array antenna.  The complexity of the Butler beamforming network increases with the number of ele­ ments. 
 may be found from a straightforward application of Eq. (9.10); therefore  (12.16)  Note that Tc, T.,11, and 'I'rr are actual temperatures while T., and Tr~ are effective noisi.:  temperatures.  In general, the contributions to the total effective system noise temperature may be  divided into three categories: (1) the effective space noise temperature, (2) the effective noise­ temperature contributions due tp RF lossy components, and (3) the effective noise tempera­ ture of the receiver itself. 
 There is no simple formula or step-by-step guide for the design of an air-surveillance  radar. One place to start, however, is with the proper form of the radar equation, along with a  clear understanding of the task to be accomplished by the radar and knowledge of the con­ straints imposed by the environment. Quite often there is more than one factor affecting the  selection of a particular radar characteristic, and these factors are sometimes conllicting. 
 Fig- ure 22.10 illustrates the special case of equatorial orbits and the number of vehi- cles required for continuous coverage. This situation is limited to the use of wide swaths that extend up to the specific latitudes indicated. It is seen that four ve- hicles can cover a 60° swath when the vehicles are at altitudes greater than about 6000 nmi. 
 The superiority of the monostatic radar even seems to extend to the application of the radar  fence. Although less equipment is needed with the bistatic-radar fence, this advantage is offset  to a large extent by the difficulties involved in extracting the target's position.  The bistatic radar deserves credit for its historical role in the early days of radar in leading  to the development of monostatic radar. 
 The SAR has been described as a side-looking radar wi,h the antenna  beam directed perpendicular to the path of the vehicle such that the dopplcr frequency of  scatterers illuminated by the center of the antenna beam is zero. It is possible. however, to  operate with the antenna beam pointed either forward or art of broadside. 
 The coverage of each beam pair may be increased by aperture weighting. In this case the beams may be stacked at greater separa- tions but will possess reduced crossover sensitivity. The normalized crossover sensitivity associated with a pair of uniformly illuminated sum beams spaced at Aw = 1 is approximately 1.8. 
 G. Marangoni, and W. G. 
 NOISE POWER RATIO34#  SENSITIVITY TIME CONTROL473  TRACK 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°xÇ  ' 6 4RUNK AND * $ 7ILSON  h4RACK INITIATION OF OCCASIONALLY UNRESOLVED RADAR TARGETS v  )%%%  4RANS  VOL !%3 
 The need  for a weighting filter is the result of the near -rectangular spectrum generated by the linear  chirp. For the case described above, the use of weighting to reduce the pulse compression side lobes introduce s a mismatch loss of 1.48  dB. The output side lobe levels can be i mproved  somewhat if the matched filter in Figure 12.16 is replaced by the phase -only ve rsion (constant  amplitude response) when used in conjunction with the Gaussian weighting filter (see [1 ],  Figure 9 and 10). 
            !     . £n°ÎÓ  2!$!2 (!.$"//+  #ENTIMETER 
 7.3. Wheeler, H. A.: A Survey of the Simulator Technique for Designing a Radiating Element in a  Phased-Array Antenna, "Phased Array Antennas, Proceedings of the 1970 Phased Array Antenna  Symposium," Artech House, Inc., Dedham, Massachusetts, 1972, pp. 
 NOISE FRONT 
 The loss tothereceived signal inpassing through anunfired TR tube isfrom 1.0to1.5db,occurring mainly inthewalls ofthecavity.. SEC.11.5] DUPLEXING AND TR SWITCHES 411 Figure 11.17 shows acut-away view ofanother type ofTR tube, the 1B24, which iswidely used inthe3-cm band. Itisoftheintegral-cavity type—that is,allofthecavity contains gas, notjust thecentral portion. 
 6.27, producing the  I/Q demodulator output as represented by Eq. 6.28.  V A tA je eSS j t j t IF= + = −+ − +sin( ) ( )( ) ( )w qw q w q 2 (6.25)  V A t j t j A eR Rj t COHO= + =−sin( ) c os( ) w ww 0 00 (6.26)  V VAe e A eAS j t j t Rj t S IFCOHO= − =+ − + − 20 ( )( ) ( ) w q w q w A AeA AeR j t S R j t 2 20 0 [( ) ] [( ) ] w w q ww q − + − + +−      (6.27)  V j VA At jA A I QS R S R+ = − + + −2 20 0 cos[( ) ] s in[( ) w w q wwt tA AeS R j t+ =− + qw w q]( ) 20      (6.28) In implementing an I/Q demodulator, it is important to provide well-balanced   I and Q channels in order to maximize image rejection, as explained below. 
 The constrained.feed utilizes  waveguide or other microwave transmission lines along with couplers, junctions, or other  power distribution devices. , The I space feed distributes the energy to a lens array or a . JIii' Fl ITIRONICAII Y STHRFD PIIASFD ARRAY ANTl'NNA IN RADAR J07  --~------------'  Figure fUI Planar array with phase-shift volumetric scan in two angular coordinates. 
 TATIVE MANNER  THE PERFORMANCE OF THE RADAR AGAINST POINT TARGETS IN PREDEFINED CLUTTER CONDITIONS &OR THIS REASON  SOME BASIC PERFORMANCE TESTS HAVE NECESSARILY BEEN LOOSELY DEFINED TO ALLOW SCOPE FOR APPROVED TEST LABORATORIES TO MAKE THEIR OWN QUALITATIVE JUDG 
   2%&,%#4/2 !.4%..!3   £Ó°£ 4HE BASIC PARABOLIC CYLINDER GEOMETRY IS SHOWN IN &IGURE  4HE REFLECTOR  SURFACE IS DEFINED AS  ZY FF 
 13.3.4  Modulation Procedures   As is represented above are presently very many dif ferent modulation procedures used.  The  most successful will be that form of modulation, which best handles multiple targets.   13.3.4.1  FM-CW Modulation Procedures   The most frequently used modulation procedure is FM -CW. 
 M.: A Note on Doppler-Shifted Signals, Proc. IEEE, vol. 54, pp. 
 R. A. Poisel, Electronic Warfare Target Location Methods , Norwood, MA: Artech House, Inc., 2005. 
 Weinberg: Digital Multiple Beamforming Techniques for Radar, I £EE  EASCON '78 Record, pp. 152-163, Sept. 25-27, 1978, IEEE Publication 78 CH 1354-4 AES. 
 P. Norris, “The future of racons,” Final Report, Contract No 237293, General Lighthouse  Authorities, London, 2006. 33. 
 Thus, it was necessary to perform phase unwrapping on the interferometric phase image. The branch cut method was applied to interferometric phase unwrapping [ 25,26]. In addition, to reduce the complexity of phase unwrapping, we also removed the ﬂat phase of the interferometric phase. 
 ,AYER -ETEOROL  VOL   PP n    " & +URYANOV  h4HE 3CATTERING OF SOUND AT A ROUGH SURFACE WITH TWO TYPES OF IRREGULARITY v   3OV 0HYS !COUST  VOL   PP n    7 * 0LANT  h"RAGG SCATTERING OF ELECTROMAGNETIC WAVES FROM THE AIRSEA INTERFACE v IN  3URFACE 7AVES AND &LUXES #URRENT 4HEORY AND 2EMOTE 3ENSING   CHAP   ' , 'EERNAERT  AND 7 * 0LANT EDS   $ORDRECHT  .ETHERLANDS 2EIDEL    ! 3CHMIDT  6 7ISMANN  2 2OMEISER  AND 7 !LPERS  h3IMULTANEOUS MEASUREMENTS OF THE  OCEAN WAVE RADAR MODULATION TRANSFER FUNCTION AT ,  # AND 8 BANDS FROM THE RESEARCH PLATFORM .ORDSEE v * 'EOPHYS 2ES  VOL   PP n    7 0 0LANT  h! STOCHASTIC  MULTISCALE MODEL OF MICROWAVE BACKSCATTER FROM THE OCEAN v   * 'EOPHYS 2ES  VOL   NO #  P     6 +UDRYAVTSEV  $ (AUSER  ' #AUDAL  AND " #HAPRON  h! SEMIEMPIRICAL MODEL OF THE NORMAL 
 The basic computational element in an FFT is the butterfly,  shown in Figure 25.41.  In the butterfly operation, one input is phase shifted and then added to and subtracted  from a second input to form two outputs. This structure is referred to as a radix-2 but - terfly because it has two inputs. 
 Wilson, “1-35 GHz microwave scatterometer,” in  Proc. IEEE/MTT-S, Int. Microwave Symp ., IEEE 79 CH1439-9 MIT-S , 1979. 
 AXIS  WHERE  2G   GROUND RANGE &IGURE  B SHOWS A VIEW FROM THE   X 
 Thereisanother arrayantenna technique calledwithin-pulse scanning thatisdifferent fromthefrequency scantechnique described above.Thisothertechnique, whichisdiscussed in Sec.Pd.isamethod forgenerating multiple receiving beamsatasinglefrequency andcanbe considered morelikethestacked-beam radarthanafrequency-scan heightfinder. Interferometer.42HAninterferometer consists oftwoindividual antennas spacedsoasto obtainanarrowhcamwidth foraccurate anglemeasurement. Thephasedifference betwecn the signalsofthetwoantenna elements oftheinterferometer provides theelevation angle.asgiven byFq.(5~·1).Thistypeofanglemeasurement issimilartothephase-comparison monopulse radar.exceptthatthesizeoftheindividual antennas issmallcompared tothespacing between them.Grating looes(alsocalledinterferometer lobes)resultfromthewidespacing between the antennas. 
 For a given pulse width, the range resolution is  limited to the distance over which the pulse travels during the  time of its duration. When multiple targets are at nearly equal  distance from the radar, the return from the farthest target will  overlap the return from the first target. In this situation, the two  targets can no longer be  resolved  from each  other  with just   simple  pulses. 
 Tube pr~tection.'.~~ Power tubes can develop internal flash arcs with little warning even  though they are of good design. When a flash arc occurs in an unprotected tube, the capacitor-  bank discharges large currents through the arc and the tube can be damaged. One met hod for  ' protecting the tube is to direct the arc-discharge currents with a device called an elrcrro~~~c  crowbar. 
 2591- \-H, July 1959. 37. Hiatt, R. 
 However, it cannot guarantee consistency of positions and numbers of all scattering points in each channel, and integrity of the cross-information of channels is destroyed, which are not favorable for target scattering information extraction. In addition, complementarity and redundancy among multi-channel data does not fully exploit in the single-channel independent CS approach, so it cannot further improve the SNR gain and reduce data volume of the system. 158. 
 Coleman111 combined the thunderstorm  activity maps of Kotaki110 with numerical ray-tracing and modeled antenna patterns  to demonstrate that the directional variability of noise, coupled with the directional  characteristics of different antennas, can lead to marked changes in noise outcomes  and hence in optimal radar design. Another important issue is the behavior of the external noise field as a function of  time, that is, within the coherent integration interval since this impacts strongly on  signal processing for interference rejection.112 Other effects that can influence radar  performance are sometimes mistaken for the  additive noise discussed above. One of  FIGURE 20.19  Noise power per hertz is given for 38.65' north latitude and 76.53' west longitude in winter:  (a) 1800 UTC is given as a daytime example and ( b) 0800 UTC is given as a nighttime example. 
 However, its rangeaccuracy wassuperior tothatobtained withopticalmethods. TheSCR-268 remained thestandard fire-control equipment untilJanuary, 1944,whenitwasreplaced bytheSCR-584 microwave radar.TheSCR-584 couldcontrolanantiaircraft batterywithoutthenecessity for searchlights oropticalangletracking.. (n1939theArmydeveloped theSCR-270, along-range radarforearlywarning. 
 Constraints imposed by propa - gation and the availability of unoccupied frequency channels dictate that the range  resolution of HF radars is not nearly as good as that of microwave systems. The HF  transmitter has to maintain stringent control of its radiated signal spectrum so as to  avoid interference to other users of the HF spectrum. (A similar consideration applies  to microwave radars, but not to the extent that it does at HF. 
 The gentle decay in the plateau region of the waveform  results from antenna pattern attenuation and ideally  should be exponential. Deviations from the ideal result  from waveform sample gain variations that, in turn, re­ flect in-band ripple and band-edge rolloff of anti-aliasing  low-pass filters in the altimeter receiver. These effects  JOhIlS Hopkins APL Technical Digesr. 
 Howard and D. C. Cross, “Mirror antenna dual-band light weight mirror design,” IEEE  Trans ., vol. 
 It would be much more efficient, in this case,  to use one multiplier to perform as many products as possible. This technique, called  time-domain multiplexing,  requires additional logic to control the system and provide  the correct operands to the multiplier at the right time. Since an FPGA can incorporate  hundreds of multipliers, one can appreciate the power of this technique. 
 Radar Interferometry: Data Interpretation and Error Analysis ; Kluwer Academic: New York, NY, USA, 2001. 4. Zebker, H.; Villasenor, J. 
 W. M. Waters and B. 
 This fluctuation must be taken into account in the calculation of probability of detection, as will be discussed in Sec. 2.4. When a fluctuates, the value to be used in the range equation as formulated here is the time average. 
 13.2. Tlie iticsic1t~tlc.r  angle is defined relative to the normal to the surface; the grazing angle is defined with respect to  ttie tangent to the surface, and the depressiot~ ar~gle is define@ with respect to the local horizon-  tal at the radar. When the earth's surface can be considered Rat, the depression angle and the  grazing angle are the same. 
 IEEE T rans. Inf. Theory 2007 ,53, 4655–4666. 
 Hansen,  vol. III, New York: Academic Press, 1964. 26. 
 14.Dunn,J.H..andD.D.Howard: Precision Tracking withMonopulse Radar,Electronics, vol.33,no. 17.pp.51-56.Apr.22.1960. 15.Barton. 
 ~~ ........ ~~..._~........,'---'----'~-'---'~~--'  8 9 10 . It 12 13 14 15  Threshold-to-noise ratio vrY211'o, dB  Figure 2.5 Average time between false alarms as a function of the threshold level V, and the receiver  bandwidth B; t/10 is the mean square noise voltage. 
 Without the second limiter, a strong-point reflector that was 58 dB above noise at the  canceler input would have a residue 28 dB above noise at the canceler output. This  would be indistinguishable from an aircraft target. It the transmitter noise were 15 dB less than assumed above, the first limiter would  be set 43 dB above thermal noise and much less target suppression would occur. 
 vol.I,Monopulse Radar." ArtechHouse,Inc.,Dedham, Mass.,1974(a collection of26reprints fromtheliterature ofmonopulse radar). 19.Downey, E.J.,R.H.Hardin.andJ.Munishian: ATimeDuplexed Monopulse Receiver. Con!Proc.on MilitaryElectronics COlII'.(IRE),1958.p.405. 
 \OI. MTT-10, pp. 536-548, November, 1962. 
 Power output degrades by 20*log (1– b) as devices fail, where b  is the fraction of  failed devices.7 This results because a large number of solid-state devices must be  combined to provide the power for a radar transmitter, and they are easily combined  in ways that degrade gracefully when individual units fail. ● The ability to demonstrate wide bandwidth is a significant characteristic of solid- state devices. While high-power microwave radar tubes can achieve 10 to 20% band - width, solid-state transmitter modules can achieve up to 50% bandwidth or more  with acceptable efficiency.FIGURE 11.1  By combining the outputs of thousands of transistor amplifiers,  the cumulative average power output of solid-state technologies can effectively  compete with the performance capabilities of vacuum tube technology, as shown  in the center overlap region where competing amplifier solutions coexist. 
  FOR  TWO PULSES    
 Some of these systems achieve a precision of the order of 0.1 mil in angle and a range accuracy of 5 yd. This chapter describes the conical-scan, sequential-lobing, and monopulse (both phase comparison and amplitude comparison) tracking-radar techniques, with the main emphasis on the amplitude-comparison monopulse radar. 18.2 SCANNINGANDLOBING The first technique used for angle tracking of targets by radar was to sense the target location with respect to the antenna axis by rapidly switching the antenna beam from one side of the antenna axis to the other, as in Fig. 
 Most of the advantages of a digital MTI  Ilrocessor are due to its use of digital delay --- lim rather than analog delay lines which are  cllaracteri7ed by variations due to temperature, critical gains, and poor on-line availability.  A simple block diagram of a digital MTI processor is shown in Fig. 4.21. 
 OF 
 The backscatter from the earth's surface is generally many orders of magnitude larger  than the echo from desired moving targets. Thus HF radar must employ some form of doppler  processing such as MTJ, pulse-doppler, FM-CW, or CW radar to separate desired moving  targets from clutter. The equivalent of a high-pass filter must be used to detect moving airr.raft  and missiles and reject stationary surface clutter. 
 For a 15-kt wind,  this is only about 2 ft, but for gale-force winds of 40 kt, it rises to almost 15 ft, which  is a rather formidable sea. Looking at the sea, an observer might describe what is seen in terms of a subjective  state of the sea , e.g., “smooth,” “rough,” or “terrifying!” If these descriptions are listed  in order of severity and assigned numbers, these numbers define a sea state . A similar  numerical scale exists for wind speeds, the Beaufort wind scale , with numbers about  an integer higher than the corresponding sea state. 
  FIGHTER  AS COMPUTED HERE BY .%# APPLIED TO A WIRE 
 Initspresent technical state, theskiatron ismost useful forobserving and plotting the courses ofships, from either ashipboard oracoastal station. Itisless satisfactory when used todisplay aircraft signals, because ofthepoor contrast intheir more rapidly moving echoes. RapidPhotographic Pro.iection.-The inadequacies ofother methods ofproviding alarge projection display ofaradar indlcat orledtothe development, by the Eastman Kodak Company, ofmeans for the photography ofone full360° sweep ofaPPI, rapid photographic process- ingofthe exposed film, and immediate projection ofthe developed pic- ture. 
 In this way the sum of such characteristics, as sensitivity, dynamic  range, reproducibility, coherency, polarimetry and bandwidth, have been greatly advanced by new orders of magnitude.  Figure 11.5 shows a simplified block diagram of the Radar cross -section measurement proc e- dure upon the basis of vector -network analysis for the case of a quasi -monostatic, polarimetric  antenna configuration.  A frequency synthesizer transmits discrete frequencies over the mea s- uring bandwidth during a cycle. 
 299–304, 2003. 132. T. 
 Bendat, J. S.: "Principles and Applications of Random Noise Theory," chap. 10, John Wiley & Sons,  Inc., New York, 1958. 
 9.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 of orbital parameters to correct the radar beam movement to update the original   set of orbital parameters, and by this means, the radar antenna axis can be held on  target with minimum error. Improved tracking can also be provided on other targets where the approximate  trajectory can be anticipated. However, performance of on-axis tracking is limited  when tracking targets with unanticipated maneuvers. 
 Southworlh, G. C.: "1-orty Years of Radio Research." Gordon and Breach, New York, lc)02.  pp. 
 detection by U-Boats 19 Group Experiment, ORC Coastal Command Report No. 146, October 1941 (TNA AIR 2/5073) [14] Disappearing Contacts with Mk. II ASV, ORS/CC Report No. 
 47, pp. 430–435, March 1959. 41. 
 An example of the CW radar principle is the radio proximity  {VT) fuze, used with great success during World War II for the fuzing of artillery projectiles. It  may seem strange that the radio proximity fuze should be classified as a radar, but it fulfills the  same basic function of a radar, which is the detection and location of reflecting objects by  "radio" mcans.3·4  Isolation between transmitter and receiver. A single antenna serves the purpose of transmission  and reception in the simple CW radar described above. 
 TERMINAL DEVICE  TYPES AND THEIR  ASSOCIATED TECHNOLOGIES AS UTILIZED FOR THE COMMON RADAR BANDS ARE DESCRIBED IN THE  FOLLOWING SECTIONS 3ILICON "IPOLAR *UNCTION 4RANSISTOR  4HE SILICON BIPOLAR JUNCTION TRANSISTOR  "*4  WAS THE EARLIEST OF THE MICROWAVE POWER DEVICES AND FOUND ITS WAY INTO TUBE  REPLACEMENT TRANSMITTERS AND PHASED ARRAY APPLICATIONS STARTING IN THE LATE S !T LOWER FREQUENCIES  ESPECIALLY BELOW   '(Z  THE 3I "*4 HAS BEEN SHOWN TO BE CAPABLE  OF VERY HIGH POWER LEVELS FOR TRANSISTORS !MPLIFIER DESIGN IS REALIZABLE FOR FREQUENCIES UP THROUGH 3 BAND  WHERE THE TRADEOFF BETWEEN DEVICE PERFORMANCE AND OVERALL SYS 
 Ling, Time-Frequency Transforms for Radar Imaging and Signal Analysis ,  Norwood, MA: Artech House, 2002. 48. L. 
 A conceptual design is based on the requirements for  the radar that will satisfy the customer or user of the radar. The result of a conceptual  design effort is to provide a list of the radar characteristics as found in the radar equa - tion and related equations and the general characteristics of the subsystems (transmit - ter, antenna, receiver, signal processing, and so forth) that might be employed. The  radar equation is used as an important guide for determining the various tradeoffs and  options available to the radar system designer so as to determine a suitable concept to  meet the desired need. 
   )NTERNATIONAL %LECTROTECHNICAL #OMMISSION  'ENEVA    h2ECOMMENDATION ! 
 Such information can be used to track and catalog the interference sources in or- der to properly react to them. The superresolution concept was mainly developed and analyzed by W. F. 
 Liu, K. H. Kellogg, K. 
 Suppose that a tower of height h (h  H)  is in the area that is imaged. We describe locations within the image by a coordinate  system ( x1, y1). If the base of the tower is at ( x10, y10), we wish to ascertain the image  coordinates of the top of the tower. 
 Internal reflections due to mismatch in the feed can  appear as spurious sidelobes in the radiation pattern.80  Space feeds. There are two basic types of space feeds depending on whether they are analogous  to a lens or to a reflector. The lens array, fig. 
 This iseasily accomplished through the medium ofaresistor inseries with theintegrating condenser ofthesaw- tooth generator, asisexplained inSec. 13.14. Thk form ofresolved-current PPI has been successfully used inthe lightweight airborne equipment (AN/APS-10) described inSees. 
 The  lower integral is taken outside the main-beam region. This assumes the sidelobcs are well  distributed in azimuth. The constant K is the average gain of the delay line canceler (K = 2 for  a two-pulse canceler and 6 for a three-pulse canceler.) The combined improvement factor for  DPCA and the sibelobe limitation is  l + I~, l nrcA (4.41)  Adaptive array antennas may be employed to compensate for platform motion in an  AMTI radar.6' The full array is illuminated on transmission so that the transmit pattern is the  same from pulse to pulse. 
 Opt. 2010 ,49, E83–E93. [ CrossRef ][PubMed ] 5. 
 crv (METERS PER SECOND) FIG. 15.14 MTI improvement factor as a function of the rms velocity spread of clutter for a three-pulse binomial-weight canceler. they establish upper bounds on the achievable performance in a precisely speci- fied clutter environment. 
 This is accomplished after the second detector in the  video portion of the receiver. The error signal is compared with the elevation and azimuth  reference signals in the angle-error detectors, which are phase-sensitive detectors. 3 7 A phase­ sensitive detector is a nonlinear device in which the input signal (in this case the angle-error  signal) is mixed with the reference signal. 
 I-fAmpliiier Design—In anideal i-famplifier, allthe noise would originate inthegenerator connected toitsinput terminals-that is, B+ Fm.12.4.—Pentode input circuit.thecrystal that serves asconverter in theusual radar receiver. Inany prac- tical amplifier there are additional sources ofnoise. Thermal noise from resistances intheinput circuit and shot noise due tothe uneven flow ofelec- trons totheplate ofthefirst tube are the chief sources ofexcess noise, al- though later stages may contribute slightly. 
 BASED TRACKING SYSTEMS  THE FILTER NEEDS TO BE AIDED WITH OWN 
 Although definite differences existbetween thesetwobasicwaveforms, itwouldbe difficult toprovide preciseguidelines describing whereoneispreferred totheother.Each apillicationmustheexamined individuallytodetermine thebestformofpulsecompression to use. Otherpulse-compression waveforms. Otherpulse-compression methods includenonlinear PM,discrete frequency-shift, polyphase codes,compound Barkercodes,codesequencing, complementary codes,pulseburst,andstretch.Eachwillbediscussed briefly. 
 CALLY SCANNED RECEIVING BEAM AND MUST ADOPT A TRIAL 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 22.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 ACKNOWLEDGMENTS 1. 
 A ﬁne focus adjustment is necessary to obtain a sharp landmass image on the PPI. Because of the various factors introducing errors in radar rangemeasurements, one should not expect the accuracy of navigational radar to be better than + or - 50 yards under the best conditions. FACTORS AFFECTING RANGE RESOLUTION Range resolution is a measure of the capability of a radar to display as separate pips the echoes received from two targets which are on the samebearing and are close together. 
 Slavney, R. E. Arvidson, K. 
  ! $ & "#  
 Each phase bit consists of two lengths of line that provide the differential phase shift,  and two single-pole, double-throw switches utilizing four diodes.  The hybrid-coupled phase bit, as shown in Fig. 8.7, uses a 3-dB hybrid junction with  balanced reflecting terminations connected to the coupled arms. 
 Theremaining sym­ holshaveheendefinedahoveorinSec.2.14.Makingthesamesuhstitution ofEq.(14.29)into thesurveillance radarequation, Eq.(2.57),gives R1=~:~~i~'.l~ ~~, max(SIN)!OPrjGj Forjamming whichentersviatheantenna sidelobes ratherthanviathemainbeam,the right-hand sideoftheabovesurveillance radarequation wouldbemultiplied bytheratioof maximum antenna gaintothegainofthesidelobe inthedirection ofthejammer. Repeater jamming. /\.targetunderobservation byaradarcangenerate falseechoesbydelay­ ingthereceived radarsignalsand retransmitting ataslightlylatertime.Thisisaccomplished illa"crearcr jamm('/". 
 HOP PATHS  AND A SOUNDING  KM DOWNRANGE IS USED FOR TWO 
 Chestori: Wide Band Phase Shifters, IEEE Trans, vol. AP-15. p. 
 The defocused ships are marked in the airborne SAR image in Figure 15. The two ships are numbered as ship05 and ship06. The resolution of the airborne SAR image is higher than that of the spaceborne SAR images. 
   PP n      7 * 0IERSON AND , -OSKOWITZ  h! PROPOSED SPECTRAL FORM FOR FULLY DEVELOPED WIND SEAS  BASED ON THE SIMILARITY THEORY OF 3 ! +ITAIGORDSKII v  * 'EOPHYS 2ES   VOL   NO     PP n     + (ASSELMANN  $ " 2OSS  0 -ULLER  AND 7 3ELL  h! PARAMETRIC WAVE PREDICTION MODEL v   * 0HYS /CEANOGR  VOL   PP n     4 %LFOUHAILY  " #HAPRON  + +ATSAROS  AND $ 6ANDEMARK   h! UNIFIED DIRECTIONAL SPECTRUM FOR  LONG AND SHORT WIND 
 The radiation-intensity pattern for rectangular apertures can often be  written as ttie product of the radiation-intensity patterns in the two coordinate planes; for  instance,  Tlic cornplete radiation patter11 can be specified from the two single-coordinate radiation  ~xittcrt~s irl the 0 plarie arid the d, plane.  Since the average radiation intensity over a solid angle of 4n radians is equal to the total  power radiated divided by 4n, the directive gain as defined by Eq. (7.1) can be written as  4lr(rnaxitnum power radiatedlunit solid angle) GD = total power radiated by the antenna  This equation indicates the procedure whereby the directive gain may be found from the  radiation pattern. 
 PLE  IF A GROUP OF ORBITAL TRAJECTORIES FALLS WITHIN A SMALL RADIUS OF EACH OTHER WHEN OVER AN AREA OF INTEREST  THEN RADAR MEASUREMENTS FROM SEVERAL ORBITS MAY BE COMPARED COHERENTLY  THUS POTENTIALLY SENSITIVE AT THE ORDER OF A WAVELENGTH TO CHANGES IN THE SCENE BETWEEN OBSERVATIONS 3UCH COHERENT CHANGE DETECTION IS A STANDARD TECHNIQUE IN THE FIELD OF SPACE 
   -4) 2!$!2  Ó° )N THE -4$  ONE OR MORE HIGH 
 VALUE PROBLEM WHEN THE FIELDS ON THE SURFACE OF THE SCATTERING OBSTACLE ARE SPECIFIED 4HE FIELDS ARE TYPICALLY REPRESENTED AS THE SUM OF KNOWN AND UNKNOWN COMPONENTS INCIDENT AND SCATTERED FIELDS   AND THE BOUNDARY CONDITIONS ARE THE KNOWN RELATION 
 11.1 A three-dimensional ob- ject whose profile does not vary along its length, such as the truncated rec- tangular cylinder on the left, is a finite chunk of an infinite (two-dimensional) structure having the same profile, such as the one on the right. Equation (11.3) relates the RCS of the two structures. The exact solution for the scattering by a conducting sphere is known as the Mie series,3 illustrated in Fig. 
   05,3% $/00,%2 2!$!2   {°££ &)'52%  4YPICAL PULSE DOPPLER RADAR CONFIGURATION $   ""    ""   "           "  %  "    "   !!     !!       "   ! & #!     !!  #!     !!   #!     !!   #!     !!  $  '% !     
 Theprocessofadjusting thepredicted position basedonthemeasured position isperformed withanarrowbandwidth. Thiserror­ signalbandwidth isadaptive andcanbemadeverynarrowtoobtaingoodsignal-to-noise ratio,yetthesystemwillcontinue topointopen-loop basedonthestoredtarget-trajectory prediction andthewidetracking-bandwidth oftheantenna-pointing servos.Forconvenience therange,azimuth, andelevation (r,0,4»coordinates oftheradaroutputareconverted to rectilinear (x,y,z)targetcoordinates toperform thedatasmoothing andcomparison with prediction. Inradarcoordinates, thetrackofatargetonastraight-line trajectory iscurvilinear andcangenerate apparent accelerations. 
 This implies theexistence ofavertical gradient intheconcentration ofwater vapor with, normally, the highest concentration atthe surface and decreasing upward. Atypical condition towhich such aneffect may lead isthat ofa relatively shallow layer just above thesurface withinwhich the vertical gradient ofrefractive index isnegative and exceeds the critical value of 5parts in10’perft. Such aregion iscalled a“duct” forreasons that will appear shortly, and thelevel atwhich thegradient hasjustthecritical value iscalled the “top oftheduct. 
 LINE #LUTTER "LANKING  4HE REFLECTION FROM THE EARTH DIRECTLY BENEATH  AN AIRBORNE PULSE RADAR IS CALLED ALTITUDE 
 PATTERN PEAK SIDELOBE LEVEL AT THE ANGLE OF ARRIVAL OF THE IMAGE SIGNAL 4HE CYCLIC RATE MAY BE APPROXIMATED BY THE EQUATION   FH% M  L    WHERE FM   FREQUENCY OF CYCLIC MULTIPATH ERROR  RADS  H   HEIGHT OF RADAR ANTENNA  K   WAVELENGTH  SAME UNITS AS  H  %   RATE OF TARGET ELEVATION CHANGE AS SEEN BY RADAR  RADS 4HE INTERMEDIATE RANGE IS BETWEEN THE SHORT 
 Remote Sens. 2018 ,10, 1304. [ CrossRef ] 31. 
 Requirements forantenna gain andsize \verereduced tomderate values, and finally computations supported bymeasurement showed that amicrowave system could satisfactorily meet the coverage problem. Work was then initiated leading tothe production ofaground radar, which proved tobeone ofthemost successful sets ever developed. Its design characteristics were sowell chosen that, even with the best techniques available attheend ofthewar, itcould noteasily besurpassed forairsurveillance and control. 
 WIDTH &ILTERS ARE THE MAIN SOURCE OF AMPLITUDE AND PHASE RIPPLE ACROSS THE SIGNAL BANDWIDTH AS OTHER COMPONENTS SUCH AS AMPLIFIERS AND MIXERS ARE TYPICALLY RELA 
 GE-15, pp. 185-189, October, 1977.  47. 
 Probability densityfunction forlandclutter.Muchofthediscussion regarding thestatistics of seaclutterappliesaswelltolandclutter,exceptthatthephysical mechanisms maybedifferent. Thestatistical variation ofaOfromhomogeneous terrainsuchasdesertsandsometypesof farmland cansometimes bedescribed bythegaussian probability densityfunction (pdf),so thattheenvelope oftheradarreceiveroutputisgivenbytheRayleigh pdf(Eq.IllO).H Some urbanareas,ruralareaswithbuildings andsilos,andmountainous terrainapproximate the log-normal pdf(Eq.13.11).44.45Ingeneral, neithertheRayleigh northelog-normal pdf's accurately describe thestatistics ofrealclutter,whichusually liesbetween thetwo.The Weibullpdf(Eq.13.12),whichisintermediate between theRayleigh andthelognormal, has beensuggested asapplicable tolandclutter.Table13.2listsexamples oftheWeibull parameter ex(inEq.13.12)forseveraltypesofclutterandseastate. Landcluttermodels. 
 IIA and had a peak power of 100 kW [ 2]. It required the installation of a 1.2 kW alternator in the aircraft and was double the weight of the lower power transmitters. Six sets were installed in Sunderlands. 
 which indicates that laser radar receivers are generally or greater effective  temperature (or noise figure) than low-noise microwave receivers.  The laser radar can employ the equivalent of either the microwave video receiver or the  superheterodyne receiver. The former is called an incoherent (envelope) receiver or direct  photodctection. 
   PP n  *ULY   $ + "ARTON AND ( 2 7ARD   (ANDBOOK OF 2ADAR -EASUREMENT   %NGLEWOOD #LIFFS  .*    0RENTICE 
 WEIGHT CANCELER  THE FIRST TWO TRANSMITTED PULSES INITIALIZE THE CANCELER  AND A USEFUL OUTPUT IS NOT AVAILABLE UNTIL AFTER THE THIRD PULSE HAS BEEN TRANSMITTED &EEDBACK OR INFINITE IMPULSE RESPONSE ))2  FILTERS WOULD NOT BE USED WITH A STEP 
 BAND LINEAR  ARRAY OF  LOW BAND  AND  HIGH BAND  6,0! ANTENNAS  ADJACENT  
 Ranges of 20 to 24 kiloyards were obtained on battleships and cruisers. By October, 1939,  orders were placed for a manufactured version called the CXAM. Nineteen of these radars  were installed on major ships of the fleet by 1941. 
 5.10 I'RACKING WlTti SURVEILLANCE RADAR  The track of a target can be determined with a surveillancg radar from the coordinates of the  target as rncasured from scan to scan. The quality of such a track will depend on the time  between observations, the location accuracy of each observation, and the number of extra-  neous targets that [night be present in the vicinity of the tracked target. A surveillance radar that  develops tracks on targets it has detected is sometimes called a track-while-scan (TWS) radar. 
 Estimates ofthe·'latter typeoflossmustbemadeonthebasisofprior. TiiE RADAR FQIJATION 57  experierice and experirliental observations. They tnay be subject to considerable variation and  uncertainty. 
 CAVITY 3 
 These models find important applications  to the analysis and interpretation of doppler-spread clutter. A number of phenomena have been ignored in the preceding discussion, though  their effects can be observed in some skywave radar systems. They include (i) a variety  of nonlinear processes that can occur during ionospheric propagation,59 (ii) delayed  echoes,60 focusing at the antipode, and (iii) round-the-world propagation.61 The most  significant practical exploitation of such phenomena can be found in experiments  directed at ionospheric modification. 
 55, issue 8, August 1967, p. 1425. ch04.indd   51 12/20/07   4:54:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 When dealing with SAR images, we should take both the data processed method and CNN training method into consideration. To get good performance, we should retain the important information of the images and get enough images when we make data augmentation and use some good models for training to reduce the amount requirement of training set. In this paper, we proposed a new method for SAR ship classiﬁcation. 
 using vacuum-tube technology, as part .of the United States Air Force's SAGE  air-defense system developed by MIT Lincoln Laboratory. In this form ADT was physically  large, expensive, and difficult to maintain. The commercial availability in the late 1960s of the  solid-slate minicomputer, however, permitted ADT to be relatively inexpensive, reliable, and  of sniall size so that it can be used with almost any surveillance radar that requires it. 
 ($)# ** ("  * %+)  
 The hybrid-coupled phase shifter generally has less loss than the other two, and uses the  least number of diodes. It can be made lo operate over a wide band. The switched-line phase  shifter uses more diodes than the other types and has an undesirable phase-frequency response  which can !:re corrected at the expense of a higher insertion loss. 
 (ILL    P  ' -IE  h"EITR ÅGE ZUR /PTIC TRÓBER -EDIEN  SPEZIELL KOLLOIDALER -ETALL ÕSUNGEN ;#ONTRIBUTION TO  THE OPTICS OF SUSPENDED MEDIA  SPECIFICALLY COLLOIDAL METAL SUSPENSIONS= v  !NN 0HYS  VOL     PP n    * 2 0ROBERT 
 (iv) The probability PFT of detect - ing a false target produced by a jammer entering through the radar sidelobes. PFT is  the probability of associating ( u, v) with H1 when H2 is true; it is a function of JNR,  the thresholds a and F, and the gain margin b. (v) The probability PTB of blanking  a target received in the main beam. 
 ,-/ -Ê  Ê**  /" - 4HE PRIMARY BENEFIT OF PULSE DOPPLER RADAR IS ITS ABILITY TO DETECT SMALL 
  AND BEAMWIDTHS  THE RANGE  AND THE GRAZING ANGLE )F THE FOOTPRINTS ARE ASSUMED TO BE OF THE  COOKIE 
 The possibility of using the proposed algorithm in several applications in the ﬁeld of Earth observation, interferometry and multi-temporal interferometry should be a goal to pursue even when mission parameters are unknown. To assess the performance obtained by the proposed approach with respect to the speciﬁc parameters of the ERS missions, a comparison of some speciﬁc radiometric parameters was carried out. The radiometric parameters table for ERS mission is reported in the Table 2. 
 Thissetsapractical upperlimitto thesizeofanantenna thatcanhaveaDolph-Chebyshev patternandtherefore setsalower limittothewidthofthemainbeamwhichcanbeachieved. Ta~loraperture illumination. TheTayloraperture illumination isaI~alizable approximation to theDolph-Chebyshev illumination.84Itproduces apattern withuniform sidelobes ofa specified value,butonlyinthevicinityofthemainbeam.Unlikethetheoretical Dolph­ Chehyshev pattern, thesidelobes oftheTaylorpatterndecrease outsideaspecified angular region.Thesidelohe levelisuniform withintheregiondefined byI(dl..1.)sin¢I<iiand decreases withincreasing angle¢forI(dj..1.)sin¢I>n,andwherenisaninteger,disthe antenna dimcnsion andAisthewavelength. 
 VARYING POLARIZATION TRANS 
 PULSE FILTERS FOR TARGETS AT  A  F 4     B   &T     F 4     AND  C  COMBINED RESPONSE  OF COMPLETE BANK OF FIVE SIX 
  AND HIGH 
 (25.7) or similar methods. For stable PRIs, time synchronization can be accomplished indirectly by using identical stable clocks at the transmitter and receiver sites. The clocks can be synchronized periodically, for example, whenever the transmitter and receiver are within LOS or located together if one or both are mobile. 
 It should be noted that GPR systems often operate in intimate contact with the  ground and very close to the target. Thus the antenna radiates in the near-field whereas  some geophysical GPR systems operate at longer ranges (10 m to 2 km), and they  ch21.indd   13 12/17/07   2:51:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 IIIA, pp. 362-370.  Scptcniher. 
 The switching signal always “leaks” through theclamp tube tosome extent bycapacity coupling, particularly atthe “off-point .“ For this reason theswitching signal should benosteeper orlarger than necessary. Because ofthis, pentodes aresometimes used insuch circuits asthose of Fig. 13.24a and 13.25a. 
 FASTv BOATS IN DYNAMIC INTERACTION WITH THE SEA SURFACE &)'52%  2#3 FREQUENCY DEPENDENCE OF A ROD MONOPOLE  AND A HEMISPHERE ON A PERFECTLY CONDUCTING  PLANE FOR VERTICAL INCIDENT AND SCATTERED POLARIZATION .   (& /6%2 
 For early-generation airborne radars, which employed a noncoherent pulse waveform, CW injection was the only practical solution. With the advent of coherent PD radars, an alternative way to achieve virtually CW op- eration without the penalty of the additional transmitter became available. This was to select a high-PRF (pulse repetition frequency), high-duty-cycle (30 to 50 percent) waveform and to use only the central line of the PD spectrum, both in the radar and in the seeker. 
 Frequencies higher  than S band are seldom used for long-range air surveillance.  High-power, large antenna apertures, and good MTI are easier to achieve at frequencies  below L band. Also, weather clutter is much less. 
 SIBLE  BUT THE GAP  S  BETWEEN CONDUCTORS MUST BE SUBSTANTIALLY LESS THAN  K TO CUTOFF  AND PREVENT SIGNIFICANT TRANSMISSION OF ELECTROMAGNETIC ENERGY THROUGH THE SURFACE 4HE ATTENUATION  IN DECIBELS  THROUGH THE PASSAGE DEPTH  T IS APPROXIMATELY  TS  PLUS  FRINGING LOSSES  WHICH ARE APPROXIMATELY K  S  
 D. Turley, “Experimental evaluation of adaptive beamforming  methods and interference models for high frequency over-the-horizon radar,” Multidimensional  Systems and Signal Processing – Special Issue on Radar Signal Processing Techniques , vol.14,  no. 1/2/3, pp. 
 (From Ref. 7.)DIGITAL INPUT8 CELLS 7 CELLS RANK (4 BITS) MOVING WINDOW . adaptive and maintains a low Pfa when the reference samples are correlated. 
 Gossard. E. E., D. 
 1.1.  Although the typical radar transmits a simple pulse-modulated waveform, there are a  number of other suitable modulations that might be used. The pulse carrier might be  frequency- or phase-modulated to permit the echo signals to be compressed in time after  reception. 
 RIER  AND CAN BE FURTHER REDUCED THROUGH LIMITING -ODERN MIXERS TYPICALLY PROVIDE A SIGNIFICANT REDUCTION IN THE EFFECT OF 34!,/ AMPLITUDE MODULATION AS THEIR CONVERSION  GAIN IS RELATIVELY INSENSITIVE TO ,/ POWER VARIATION WHEN OPERATED AT THEIR SPECIFIED  DRIVE LEVEL &OR SYSTEMS REQUIRING HIGH SENSITIVITY  !- NOISE CAN BECOME DISRUPTIVE IF UNIN 
 Wirth, Radar Techniques Using Array Antennas , London, UK: IEE Radar, Sonar,  Navigation and Avionics, Series 10, 2001.  103. J. 
 7. sensors Article A Novel Multi-Angle SAR Imaging System and Method Based on an Ultrahigh Speed Platform Wensheng Chang, Haihong T ao, Guangcai Sun *, Yuqi Wang and Zheng Bao National Laboratory of Radar Signal Processing, Xidian University, Xi’an 710071, China; victorycws@163.com (W.C.); hhtao@xidian.edu.cn (H.T.); xdwangyuqi@163.com (Y.W.); zhbao@mail.xidian.edu.cn (Z.B.) *Correspondence: gcsun@xidian.edu.cn Received: 20 January 2019; Accepted: 3 April 2019; Published: 10 April 2019/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: Considering the difﬁculty of pulse repetition frequency (PRF) design in multi-angle SAR when using ultra-high speed platforms, a multi-angle SAR imaging system in a uniﬁed coordinate system is proposed. The digital multi-beamforming is used in the system and multi-angle SAR data can be obtained in one ﬂight. 
 SENSING DEVICE  THE ECHO SIGNAL PROPAGATING IN SPACE WAS ANALYZED  SHOWING THAT THE ANGLE NOISE IS PRES 
 It is  iritcrcsting to note that the dcvclopmcnt of si~ch a capability was originally not as an attempt  to Icilrn niore about tlic sea. t3irt was a byproduct of attempts to iniprove tlic detection or  targets in a sea-clutter background.  111; radar equation. 
 The posi - tion gain a is nearly identical for the Q(tk) models no. 1, 2, 3, and 5 in Table 7.4.  However, the velocity gain b differs considerably. 
 TO 
  BOMBER AT A FREQUENCY OF  '(Z . £{°£{  2!$!2 (!.$"//+  !N EMPIRICAL FORMULA FOR THE 2#3 OF A NAVAL SHIP IS   R F$    WHERE d IS THE RADAR FREQUENCY IN MEGAHERTZ AND  $ IS THE FULL 
 &)'52%  -EAN IMPROVEMENT FACTOR RESTRICTION VERSUS AMOUNT OF LIMITING AND  CLUTTER SPECTRAL SPREAD FOR A FOUR 
 The dispersive strip delay line uses the phenomenon that if acoustic energy is propagated through a medium as a longitudinal wave, the medium exhibits a nearly linear delay-versus-frequency characteristic over an appreciable frequency range. The strip width is not critical as long as it is greater than 10 acoustic wavelengths. The thickness, however, is very critical and must be about one-half of an acoustic wavelength at a frequency equal to the center of the linear delay-versus-frequency characteristic. 
 The numerator of the second factor is the target cross section a in square meters. The denominator accounts for the divergence on the return path of the electromagnetic radiation with range and is the same as the denominator of the first factor, which accounts for the divergence on the outward path. The product of the first two terms represents the power per square meter returned to the ra- dar. 
 Trailing- edge contributions like these are excited by that component of the incident elec- tric field perpendicular to the edge; therefore they are stronger for horizontal in- cident polarization than for vertical polarization. A flat plate also can support multiple diffraction from one side of the plate to the other, as shown in Fig. 11.11. 
 Volta:c may beeither d-c orsome periodic function ofthe timer SUC!I asV=V,sin 2~ft. the discharging and the recharging circuit. The discharging circuit is very simple, and itsindividual components arediscussed insome detail hereafter. 
 The radar was necessary inany case toenable the aircraft carrying ittoperform its mission, and thenavigational use ofthe radar was only incidental toits main purpose. Nevertheless, theclarity and convenience ofthemap-like presentation. 612 EXAMPLES OF RADAR SYSTEM DESIGN [SEC. 
 Sensors 2019 ,19, 743   Figure 1. The location of Wuhan city in China and the study area. The red rectangle illustrates the coverage of Radarsat-2. 
 25.9, and y is a normalized reflectivity parameter. For farm- land y « -15 dB, and for wooded hills y « -10 dB.123 The constant-^ bistatic-scatter-region model is developed by using a variation of the monostatic-bistatic equivalence theorem (Sec. 25.8), where sin 0,- is re- placed by the geometric mean of the sines of the incident and scattering angles, (sin 0,- sin 0J1/2, in Eq. 
 BAND TUBE THAT WAS MECHANICALLY TUNABLE FROM  TO -(Z )T COULD OPERATE WITH A PEAK POWER OF  K7  A  §S PULSE WIDTH  AND A PULSE REPETITION FREQUENCY OF   (Z THAT PROVIDED AN AVERAGE POWER OF  7 )TS  EFFICIENCY WAS TYPICAL FOR  MAGNETRONS AT THAT TIME 4HE COMPACT SIZE AND EFFICIENT OPERATION OF THE MAGNETRON AT MICROWAVE FREQUENCIES ALLOWED RADARS IN 7ORLD 7AR )) TO BE SMALL ENOUGH TO FLY IN MILITARY AIRCRAFT AND TO BE MOBILE FOR GROUND WARFARE -AGNETRONS  HOWEVER  SEEM TO BE LIMITED TO ABOUT A FEW KILOWATTS OF AVERAGE POWER  WHICH CAN RESTRICT THEIR UTILITY 4HEY ALSO HAVE LIMITATIONS IN STABILITY AND  THEREFORE  IN THE -4) IMPROVEMENT FACTOR THEY CAN ACHIEVE  AND THEY OFTEN HAVE A SHORTER LIFE THAN LINEAR 
 The first occurs when a floodlight transmit beam is used. To a first order, sidelobe clutter levels are reduced only by the one-way receive antenna sidelobes, in contrast to two-way sidelobe clutter reduction for a monostatic radar. The second problem occurs when the transmitter and/or the receiver are mov- ing, e.g., when airborne. 
   !.&01 
 Unfortunately, the effort required to specify completely the effects of all radar pa­ rameters to the degree of accuracy required for range prediction is usually not economically  justified. A compromise is always necessary between what one would like.! to have and what  one can actually get with reasonable effort. This will be better appreciated as we proceed  through the chapter and note the various factors that must be taken into account. 
 In general, the models listed are part of a predic- tion method. Some of the prediction methods have not been well documented al- though widely distributed; also, users frequently ''improve" upon a model and prediction method to suit their specific needs. As an example, the model RADAR C of Ref. 
 The beam of radiation which had in the past been  used to search the sky for hostile aircraft could now be  made to search the ground for towns, factories, and other  solid objects which it was soon discovered gave a rather  different sort of echo back from that of the flat surround-  ing earth or sea. These built-up areas might thus be  displayed on the CRT as ‘targets’ against the weaker  response from the open country. That such a method  of detecting towns was possible had been demonstrated  previously, using a system on 14 metres, as described in  the first chapter of this book. 
 M.: Final El~gitieering Report on Angular Accuracy Improvement, General Electric  C'o. Report otr Corrtract D.A. 36-039-sc-194, Aug. 
 Microburst detection, like tornado detection, is accomplished by estimating shear. However, in the case of the microburst, it is the radial shear of the radial velocity that is typically measured. Human interpretation of microburst signa- tures in color-enhanced radial velocity displays is easily accomplished with trained observers.50 Radial velocity differences of 10 to 50 m/s are observed in microbursts. 
 Some components were unreliable, test gear and instruction books were not available and methods for measuring Figure 2.2. Pye indicator/receiver for ASV Mk. I [ 2].Airborne Maritime Surveillance Radar, Volume 1 2-3. 
 If the random variable is a noise current, the product of the variance  and resistance gives the mean power of the a-c component. The square root of the variance u is  called the standard deviation and is the root-mean-square (rms) value of the a-c component.  We shall consider four examples of probability-density functions: the uniform, gaussian,  Rayleigh, and exponential. 
 NOISE AMPLIFIER OR AFTER THE TRANSMIT AMPLIFIER 0HASE 3HIFTERS    $IGITALLY CONTROLLED PHASE 
 Figure 10. Time-series results on two feature points: ( a) CT1 and ( b) CT2 (with reference to 2014 /6/17). It can also be seen, from Figure 10b, that the rheological model results showed a slow subsidence recovery from August 2015, with a magnitude of 14 mm at CT1 and 15 mm at CT2. 
 Res. Oceans 1994 ,99, 10075–10085. [ CrossRef ] 6. 
 OF 
 In Passive Millimeter-Wave Imaging T echnology IV , Proceedings of the AeroSense, Orlando, FL, USA, 24–28 April 2000 ; SPIE: Washington, DC, USA, 2000; pp. 52–60. 7. 
 Itruns from thetransmitter upthrough thehollow azimuth shaft, inwhich there isanr-frotary joint; thence into thehollow FIG. 9.14.—The AN/TPS.10 height-finding anterm~ mount with areflector 10fthigh. elevation shaft, where asecond rotary joint isprovided; and then into thereflector atitsvertex, where itpasses through thehollow shaft ofthe sine generator, ahigh-speed rotary joint, and thehollow shaft ofthespin motor. 
 The fluctuation in the estimate necessitates  that the mean threshold be set higher than the ideal, hence a loss. It is only applicable  to targets. Guard Blanking Loss. 
 Next consider the case where tile radar observes surface clutter near perpendicular  irlcidence. (At perpendicular incidence the grazing angle 4 is 90°.) The clutter area viewed by  the radar will be determined by tlie antenna beamwidths Us and q5B in the two principal planes.  Tlie area A, in Eq. 
 1969.  8. Manasse, R.: Range and Velocity Accuracy from Radar Measurements, unpublished internal report  dated February,· 1955, MIT Lincoln Laboratory, Lexington, Mass. 
 SQUARED BEAM (OWEVER  COMPUTER SOFTWARE PACKAGES NOW EXIST THAT  ENABLE SYNTHESIS OF ARBITRARY BEAM SHAPES VIA APPLI 
 For example, with a particular X-band Varian backward-wave CFA,16 a  constant-voltage modulator produces a variation in output power from 505 k W at 9.0 GHz to  240 kW at 9.5 GHz, a change of 3.2 dB. A constant-current modulator with the same tube  results in a power variation of only 0.3 dB over the same frequency range. Since most practical  modulators are neither constant-current nor constant-voltage devices, actual performance is  somewhere in between. 
 GAUGE NETWORK !LTHOUGH RADAR MEASURES REFLECTIVITY ALOFT  THE PRIMARY CONCERN IS RAINFALL ESTIMATION AT THE SURFACE 2AIN GAUGE MEASU REMENTS ARE FREQUENTLY  USED TO ADJUST THE RADAR REFLECTIVITY VALUES  :AWADZKI DESCRIBES MANY FACTORS THAT  INFLUENCE RAINFALL MEASUREMENT BY RADAR *OSS AND ,EEAND OTHERS   USE THE  6ERTICAL 0ROFILE OF 2EFLECTIVITY 602  TO ESTIMATE THE SURFACE RAINFALL RATE WITH SOME  SUCCESS "RIDGES AND &ELDMAN DISCUSS HOW TWO INDEPENDENT MEASUREMENTS REFLEC 
 D. Burnside, T. T. 
 UJ @ -—---/ c1:-,:-d@Clutterfilter Noiseanddoppler Angledatafilter- Lf transmitterMixer(30Me/see)Mixer I‘~ LJLJU-~2fr3fr ATR — TR Mixer30Me/see oscdlatorI i‘‘@I @ Modulator Attenuator Rectifier Ii=oscillator frequency /0 w PPIsweep triggered by Squarewave 47..-— FIG.5.15.—Block diagram ofpulse-modulated doppler system.m. lr. 152 C-W RADAR SYSTEMS [SEC. 
 NER  EVERY ELEMENT IN THE ARRAY SEES EXACTLY THE SAME ENVIRONMENT  AND THE CALCULATIONS FOR ANY ELEMENT APPLY EQUALLY TO ALL 4HESE ASSUMPTIONS PROVIDE A SIGNIFICANT SIMPLIFI 
 Theuniqueproperties oftheseradarsalsomakethemofinterestfor military applications. Toillustrate thetypesofapplications wellsuitedforHFOTHradar, twoexamples willbementioned: airtrafficcontroloverthesea,andremoteobservation of seaconditions. Inthecontinental UnitedStatesandsimilarlandareasoftheworldwithlargeairtraffic, long-range microwave air-surveillance radarscankeeptrackofaircraft forthepurpose of providing safeandefficient airtravel.Suchcoverage overtheoceanisnotpractical becauseof theunavailability ofsuitable sitesformicrowave radar.Ashore-based HFOTHradarcan coverlargeareasoftheoceananddetectandtrackaircraftsoastoprovide air-traffic control. 
 Radarswith"moderate" resolution mightrequireonlyenoughimprovement factortodealwiththemedianclutter power,whichmaybe20dBlessthantheaverage clutterpower.4SAccording toShrader a medium-resolution radarwitha 2J.lSpulsewidthanda1.5°beamwidth,isofsufficient resolution toachievea20dBadvantage overlow-resolution radarsforthedetection oftargetsinground clutter.so Equipment instabilities. Pulse-to-pulse changes intheamplitude, frequency, orphaseofthe transmitter signal,changes inthestaloorcohooscillators inthereceiver, jitterinthetimingof thepulsetransmission, variations inthetimedelaythrough thedelaylines,andchanges inthe pulsewidthcancausetheapparent frequency spectrum fromperfectly stationary clutterto broaden andthereby lowertheimprovement factorofanMTIradar.Thestability ofthe equipment inanMTIradarmustbeconsiderably betterthanthatofanordinary radar.Itcan limittheperformance ofanMTIradar ifsufficient careisnottakenindesign,construction, andmaintenance. Consider theeffectofphaseyar!ations, inanoscillator. 
 The spectrum of a CW transmissiorl can be broadened by the application ofmodulation,  either amplitude. frequency, or phase. An example of an amplitude modulation is the pulse  radar. 
 634 MOVING-TARGET INDICATION [SEC. 16.3 the amplifier have separate diode detectors arranged togive opposite signal polarities, sothat the delayed and the undelayed signal can be adjusted inamplitude tocancel each other when added. Since thevideo signal from amoving target isbipolar (cf.Fig. 
 It represents one of the few analog processing devices used in modern  radar. The advantages of the SAW device are its compact size, the wide bandwidths  that can be attained, the ability to tailor the transducers to a particular waveform, the  all-range coverage of the device, and the low cost of reproducing a given design. The  major shortcomings of the SAW approach are that the waveform length is restricted. 
 SUREMENT ACCURACY AND RESOLUTION 4HE BENEFITS OF USING %##- TECHNIQUES SUCH AS FREQUENCY AGILITY  COHERENT DOPPLER PROCESSING  VERY LOW SIDELOBE ANTENNAS  AND 3,# CAN BE EASILY ASSESSED AT A FIRST APPROXIMATION BY PROPERLY MODIFYING THE PARAMETERS INVOLVED IN THE RADAR EQUATION )F  FOR INSTANCE  AN 3,# IS ADOPTED AGAINST AN 3/*  ITS NET EFFECT IS TO REDUCE JAMMING POWER BY THE AMOUNT OF JAMMER CANCELLATION RATIO THAT THE 3,# CAN OFFER 4HE PREDICTION OF RADAR RANGE IS DIFFICULT BECAUSE OF THE MANY FACTORS THAT ARE HARD  TO REPRESENT WITH MODELS OF THE REQUIRED ACCURACY 4HE FACTORS INVOLVE THE TARGET TO BE DETECTED TARGET RETURNS OF AN UNKNOWN STATISTICAL NATURE   THE NATURAL ENVIRON 
 C. Wilson: A High-Resolution Rapid-Scan Antenna, J. Res. 
 !lastings, K. N., and J. ti. 
 VOLTAGE POWER SUPPLY /THER CAUSES OF PHASE INSTABILITY INCLUDE AC VOLTAGE ON A TRANSMITTER TUBE FILAMENT AND UNEVEN POWER SUPPLY LOADING  SUCH AS THAT CAUSED BY PULSE 
 PGIT-3, pp. 26-51, March,  1954.  33. 
 It also reduces to a safe level  radiations from nearby transmitters. The receiver protector might use solid-state diodes for an  all s6lid-state c~nfiguration,~~ or it might be a passive TR-limiter consisting of a radioactive  primed TR-tube followed by a diode limiter.49*50 The ferrite circulator with receiver protector  is attractive for radar applications because of its long life, wide bandwidth, and compact  design.  Other duplexer considerations. 
      &)'52%  2AY 
 D’Acierno, M. Ceccarelli, A. Farina, A. 
 AP-24, pp. 139-143, March, 1976.  142. 
 ). 502 INTRODUCTION TO RADAR SYSTEMS  Scattering from snow. Dry snow particles are essentially ice crystals, either single or ag-  gregated. 
 92 INTRODUCTION TO RADAR SYSTEMS  techniques can be similar. Pseudorandom phase-coded waveforms40 and random noise  waveforms41q42 may also be applied to CW transmission. When the modulation period is long,  it may be desirable to utilize correlation detection instead of matched filter detection. 
 At the output of the mixer one obtains:   € ±fd=fs−fE (8.1)  With pulse Radar the behavior is different.  Figure 8.1 b demonstrates time and frequency d o- main for Radars with low PRF:  € fp=1T(T=Period ) (8.2)  The pulse duration is until today, in most cases, considerably larger than the period duration of  the microwave carriers.  Through pulse modulation, a signal of  duration τ and periodic in c y- cle to the PRF will be sent from the microwave carrier. 
 Monopulse feed horns at different microwave frequencies can also be com- bined with horns interlaced. The multiband feed clusters will sacrifice efficiency but can satisfy multiband requirements in a single antenna. AGC (Automatic Gain Control). 
 13.32. The amplified signal isapplied tothe“bottom” ofthe condenser, sothat thepotential ofXchanges only bythedifference between thecharge across thecondenser and that fedback. Thus thechange inpotential across Riskept very small and thecharging current isvery constant. 
 16.Kerr,D.E.(ed.):"Propagation ofShortRadioWaves," MITRadiation Laboratory Series,vol.13, McGraw-Hili BookCompany, NewYork,1951. 17.Goldstein, H.:Frequency Dependence oftheProperties ofSeaEcho,Phys.Rep.,vol.70,pp.938-946, Dec.Iand15,1946. 18.Katzin,M.:OntheMechanisms ofRadarSeaClutter,Proc.IRE,vol.45,pp.44-54,January, 1957. 
 TION REGION IS DUE TO THE PARAMETER SELECTION PROCESS IN RADAR OPERATION  THE FREQUENCY WOULD BE SELECTED TO MINIMIZE TRANSITION EFFECTS 4HE FREQUENCY  RADIATION ANGLE  AND NOISE POWER PER HERTZ THAT GO WITH THIS SITE AND LOOK DIRECTION ARE ALSO PLOTTED &)'52%   2ADAR PERFORMANCE 
 DRIVEN WAVES v * 'EOPHYS 2ES  VOL   PP n     ! % ,ONG AND $ " 4RIZNA  h-APPING OF .ORTH !TLANTIC WINDS BY (& RADAR SEA BACKSCATTER  INTERPRETATION v )%%% 4RANS !NT 0ROP   VOL !0 
 188–200, January 1999. 51. J. 
 ING ELEMENTS  AND BY IMPLICATION  THE MAXIMUM SPACING AVAILABLE FOR 42 MODULES WHEN THEY ARE ALIGNED BEHIND THE RADIATING ELEMENTS MUST BE ON THE ORDER OF  INCHES OR LESS !LLEVIATIONS IN PACKAGING MAY BE ALLOWABLE IF THE SCAN VOLUME IS NOT REQUIRED TO EXTEND TO A FULL FIELD OF VIEW 6ALUES OF ELEMENT SPACING THAT SATISFY %Q  ARE SHOWN AS A FUNCTION OF SCAN ANGLE FOR SOME OF THE COMMON RADAR FREQUENCY BANDS THROUGH MM 
 17.2 for the special case of horizontal motion. The foldover in range and doppler is illustrated in Fig. 17.7 for a medium-PRF radar where the clutter is . 
 The tube remains  inactive until the application of the RF input pulse starts the emission process, causing  amplification to take place. At the end of the RF drive-pulse the electrons remaining in the  tube must be cleared from the interaction area to avoid feedback which generates oscillations  or noise. In reentrant CF As, the electron stream can be collected after the removal of the RF . 
 NEIGHBOR ASSIGNMENT CAN NOW BE APPLIED TO THE ASSOCIATION TABLE BY FINDING  THE SMALLEST STATISTICAL DISTANCE BETWEEN A DETECTION AND A TRACK  MAKING THAT ASSOCIA 
    +"    SIN % D"  
 LOOK AZIMUTH RESOLUTION IS APPROXIMATELY ONE 
 ch20.indd   82 12/20/07   1:17:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 
 However, a coher-  ent reference signal may be readily obtained with the power oscillztor by readjusting the phase  of the coho at the beginning of each sweep according to the phase of the transmitted pulse. The  phase of the coho is locked to the phase of the transmitted pulse each time a pulse is generated.  A block diagram of an MTI radar (with a power oscillator) is shown in Fig. 
 BAND 3!2 SYSTEM #HARACTERISTICS AND INITIAL CALIBRATION  RESULTS v 0ROC )'!233  VOL   PP n    & 4 5LABY  2 + -OORE  AND ! + &UNG   -ICROWAVE 2EMOTE 3ENSING !CTIVE AND 0ASSIVE    6OL ) AND 6OL ))  2EADING  -! !DDISON 
 /8.Elliott,R.S;:TheTheoryofAntenna Arrays," Microwave Scanning Antennas, vol.If,"R.CHansen (ed.),Academic Press,NewYork,N.Y.,1966,chap.I. 19.Davies,D.E.N.:RadarSystemswithElectronic SectorScanning, J.Brit.JRE,vol.18,pp.709-713, December, 1958. 20.Kummer, W.H.:Feeding andPhaseScanning, "Miaowave Scanning Antennas, vol.III,"R.C. 
 PENSATE IS AN INEFFICIENT MODELING EXERCISE )N THE MODEL ONLY THE FIRST REFLECTION IS COMPUTED  ALTHOUGH MULTIPLE INTERNAL REFLECTIONS WITHIN EACH LAYER WILL BE GENERATED AND A FULL REPRESENTATION SHOULD INCLUDE THESE 4HE PARAMETERS OF THE LAYERS ARE GIVEN IN 4ABLE  &)'52%  0HYSICAL LAYOUT OF '02 SYSTEM #OURTESY )%%     
 This is shown in table2.5. It can be seen that in the later period, when Metox had been widely introduced, there were more frequent sightings of U-boats by non-ASV ﬁtted aircraft. These sightings would have mainly occurred during daylight, reinforcing the conclusion that the use of ASV during daylight had become counter-productive. 
 Beacon Rendezvous and Station Keeping.  Most modern military aircraft  depend on in-flight refueling for many missions. This requires rendezvous with tanker  aircraft during all weather conditions as well as station keeping until aircraft currently  in line for refueling depart. 
 1958. 36.Capelli, M.:RadioAltimeter. IRETrans.•vol.ANE-l, no.2,pp.3-7,June,1954. 
 51, 596-601, April, 1963, and vol. 52, pp. 708-709,  June, 1964. 
 2013 ,51, 425–435. [ CrossRef ] 128. Sensors 2019 ,19, 252 15. 
   PP n  . £È°Èä  2!$!2 (!.$"//+    & + ,I  $ #ALLAHAN  $ ,AME  AND # 7INN  h.!3! SCATTEROMETER ON .2/33A SYSTEM FOR  GLOBAL OBSERVATIONS ON OCEAN WINDS v $IG )'!233      2 + -OORE AND 7 * 0IERSON  h-EASURING SEA STATE AND ESTIMATING SURFACE WINDS FROM A POLAR  ORBITING SATELLITE v IN  0ROC )NT 3YMP %LECTROMAGN 3ENSING OF %ARTH FROM 3ATELLITES       PP 2n2   , * #OTE ET AL  h4HE DIRECTIONAL SPECTRUM OF A WIND 
 M. Kent, and G. L. 
 A stable transmitter frequency is not needed in this  system as it is in the coherent system. Coherence is obtained on a relative basis in the process  of comparing the signals received from the forward and backward direction. Changes in  transmitter frequency affect the echo signals in the two directions equally and are therefore  canceled when taking the difference frequency. 
 3KY-ED  )TALY HAS A SERIES OF FOUR #/3-/ 
 3, 6, 8 and 21, or are under construction such as Metro Lines No. 5, 7 and 11, during our study period 2015 −2018. Digging subway tunnels inevitably disturb the surrounding soil, and land subsidence is more likely to follow, especially in areas of soft soil and carbonate rock. 
 30. D. D. 
     D"  WHERE E IS THE VOLTAGE 
 Thuswithforward biasthedioderesembles a low-value resistor.Ifthediodeishousedinapackage, theparasitic elements introduced bythe package degrade theswitching actionandinfluence thevoltage breakdown andthermal characteristics. Thevariable capacitance semiconductor element, or('aractor diode,alsocanbeusedas theswitchinadiodephaseshifter.Itiscapable ofveryrapidswitching, oftheorderofa nanosecond, butcanhandleonlylowpower.Sincethecapacitance ofavaractor varieswith theappliednegative biasvoltage, itmaybeemployed asananalog(continuously variable) phaseshifterusingeithertheloadedlineorthehybridcoupled configurations. Powerlevels arelimitedtoafewmilliwatts bythegeneration ofharmonics andothernonlinear effects. 
 2.15 not require totalreflection atCDtoget appreciable guiding foracon- siderable distance. Nor does the source ofradiation have toliewithin theduct topermit aportion oftheenergy tobepartially trapped inthe duct, although itmay not betoo farabove it. The variation offield strength with distance from thetransmitter and height above thesurface isvery complicated, and tocover this type ofpropagation byamere modification oftheradar equation isentirely out ofthe question, asthe reader who pursues this subject into Vol. 
 CAVITY CIRCUIT IS CATHODE 
 November. 1976.  30. 
 Although the gain forsmall sig- 8[*64C7c, 6AG7 nals canbesimply exp~essed interms + ‘=~--------- ofthetube and circuit constants, it: -L isusually determined byreference to R.~. To ‘R,terminated thecharacteristic curves ofthetube..-_L_-CB- line Formany reasons, thehigh-frequency performance ismost conveniently= = R= expressed bygiving the frequency atwhich thegain isdown 3db(volt- age down to0.707). This will beB+ FIG. 
 DIMENSIONAL ARRAY OF BICONICAL ANTENNAS HAVE ALL BEEN USED IN SKYWAVE RADAR TRANSMIT SYSTEMS  IN SOME CASES  WITH BACKSCREENS TO IMPROVE THE OTHERWISE MEDIOCRE FRONT 
 Introduction Synthetic aperture radar (SAR) is a high-resolution imaging radar that works all-weather and all-day [ 1]. SAR is widely used in military and civil fields because it assists in target analysis [ 2–4]. Scattering of a target is aspect-dependent. 
 Recent advances in real-time analysis of ionograms and ionospheric drift measurements with digisondes. J. Atmos. 
 The typical processing construction sequence for a GaAs MMIC chip is fairly similar among the GaAs foundries.14 The active channel region of an FET is de- lineated by any of several patterning techniques on a semi-insulating GaAs sub- strate. A combination of deposited dielectric films and metal layers is used to form the passive components and also to interconnect all the elements of the cir- cuit. Standard libraries of circuit elements may include FETs (used as linear am- plifiers, low-noise amplifiers, saturating power amplifiers, or switches), resistors, capacitors, inductors, diodes, transmission lines, interconnects, and plated ground vias.Transmit PortTransmit Power Amplifiers Multiple-Bit Phase Shifters Antenna Port Receive Port Switching ControlLow Noise Receive Amplifiers Signal ProcessorBias Control Control Data Input Lines . 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 25.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 FIGURE 25.37  Frequency response of single-stage CIC decimation filter ( a) before decimation  and ( b) after decimation−70−60−50−40−30−20−100 BWBW 0 fs(in)/8 FREQUENCYGAIN (dB) fs(in)/4 fs(in)/2 3fs(in)/8 −fs(in)/8 (a) (b)−70−60−50−40−30−20−100 0 fs(out)/4 fs(out)/2 −fs(out)/4 −fs(out)/2 FREQUENCYGAIN (dB)BW FIGURE 25.38  Three-stage CIC decimation filterDtR τ+ ++ − − τ+ +τ+ +Dt+ − Dt+ − ch25.indd   30 12/20/07   1:40:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 ÓÈ°£n  2!$!2 (!.$"//+  ÓÈ°ÇÊ 
 Inthe cathode followers ofFig. 13”llb, the cathode circuit serves as the load and the plate isconnected directly toB+, resulting ina nega- tive-feedback amplifier ofgainless than 1,characterized bygreat linear- ity, excellent frequency response, high input impedance, and low output impedance. Since theentire output voltage appears across thecathode, thefeed- back ratio Pisunity. 
 119. B. Vignal, G. 
 Int. , vol. 109, pp. 
 Exceptions occur at broadside, as  mentioned, and for smaller aircraft.j8 There are also examples where no chi-square distribu-  tion can be made to fit the experimental data.  The chi-square distribution has been used to approximate the statistics of other-than-  aircraft targets. Weinst~ck~'*~~ showed that this distribution can describe certain simple  shapes, such as cylinders or cylinders with fins that are characteristic of some satellite objects. 
 COOPERATIVE MONOSTATIC RADAR  SPECIFICALLY WITH THE HITCHHIKER SUFFERING ANTENNA SCAN 
 Instead, the firststageissimplythemixer.Although thenoisefigureofamixerfront-end maynotbeaslow asotherdevices thatcanbeusedasreceiver front-ends, itisacceptable formanyradar applications whenotherfactorsbesideslownoiseareimportant. Thefunction ofthemixeris toconvert RFenergytoIFenergywithminimum lossandwithoutspurious responses. Silicon point-contact andSchottky-barrier diodes,s.24basedonthenonlinear resistance character­ isticofmetal-to-semiconductor contacts havebeenusedasthemixingelement.4•sSchottky­ harrierdiodesaremadeofeithersiliconorGaAs,withGaAspreferred forthehigher microwave frequencies. 
   WHICH CAN BE PROCESSED FURTHER IF REQUIRED  !NALOGOUSLY TO THE IMPLEMENTATION OF THE CELL 
 CHANNEL VARIATIONS USING &)2 EQUALIZATION 3ECTION   OR CORRECTION IN THE FREQUENCY DOMAIN IN THE DIGITAL SIGNAL PROCESSOR  ALLOWING THE USE OF LESS TIGHTLY CONTROLLED FILTERS È°nÊ   / 
 PLICATE THE PICTURE STILL FURTHER  IT  HAS BEEN FOUND THAT SEA CLUTTER CAN BE DEPENDENT ON  THE DIRECTION OF THE LONG WAVES  WHICH INCLUDES  SWELL IN THE MEASUREMENT AREA  SO  IDEALLY THE  DIRECTIONAL WAVE SPECTRUM  SHOULD BE MEASURED AS WELL /BVIOUSLY  IT IS  UNLIKELY THAT ALL OF THESE ENVIRONMENTAL PARAMETERS WILL BE RECORDED WITH PRECISION IN EVERY OR EVEN  ANY  SEA CLUTTER MEASUREMENT SO CONSIDERABLE VARIABILITY IN THE BASIC  CONDITIONS UNDER WHICH SEA CLUTTER DATA ARE COLLECTED BY DIFFERENT EXPERIMENTERS CAN BE EXPECTED )T IS OF INTEREST TO NOTE THAT IN MANY OF THE REPORTED MEASUREMENTS OF SEA CLUTTER  PARTICULARLY IN THE OLDER LITERATURE  WIDE INCONSISTENCIES BETWEEN WIND SPEED AND WAVEHEIGHT MAY BE FOUND &OR EXAMPLE  A WIND SPEED OF  KT MIGHT BE REPORTED WITH WAVEHEIGHTS OF  FT  OR  
 7.1Xh). Zoning is based on the fact that a 360" cliange of phase at the aperture 11x9  no eCPect on the aperture phase distribution. Starting with zero thickness at the edge of the lens,  the thickness of the dielectric is progressively increased toward the lens axis as in the design of  a riormal lens. 
 This algorithm performs correlation exploitation of the contributes of the several azimuth lines. This leaves some room for further analysis as the residual correlation is inherently present in the lower singular vectors and not only on the ﬁrst one, meaning that better image quality can be addressed using all the correlated components in the SVD decomposition. Of course, the problem is crucial, and attention is being taken on this subject. 
 16,Radiation Laboratory Series. SEC. 11.8] THEMIXER 417 minimum loss ofincoming signal into the local-oscillator input; (3)the local oscillator must seeafairly good match, though therequirements are not asstrict asforamagnetron. 
 27-33, October, 1959, and pp. 33-38, November, 1959; also discussion  hy F. J. 
 This effect, caused bythe permanent electric moment ofthe water molecule, can, insome circumstances, drasti tally affect the propagation ofmicrowaves inamanner tobedescribed inthenext section. Confining ourattention forthemoment totheatmosphere of“stand- ard” refractive properties, towhich Eq. (32) applies, letusseewhy it makes sense tospeak ofamicrowave horizon when radiation ofmuch lower frequency, asiswell known, travels farbeyond any such horizon. 
 1, 1960, pp. 48–50. 35. 
 IEEE. vol. 65. 
 Therefore 1  This is the fundamental form of the radar equation. Note that the important antenna par-  ameters are the transmitting gain and the receiving effective area.  Antenna theory gives the relationship between the transmitting gain and the receiving  effective area of an antenna as  Since radars generally use the same antenna for both transmission and reception, Eq. 
 Peter H. Stockmann, Lockheed Martin  Maritime and Sensor Systems, Syracuse, NY ) ch08.indd   14 12/20/07   12:50:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 These include the following: 1. Phase errors in cascaded stages simply add. However, it may also be pos- sible to arrange them to cancel by proper phasing of power supply ripples for dif- ferent stages. 
 20, pp. 24 and 26, March, 1977.  98. 
   NO    PP n  3EPTEMBER    2 * -AILLOUX  0HASED !RRAY !NTENNA (ANDBOOK  .ORWOOD  -! !RTECH (OUSE   - :ATMAN  h$IGITIZATION REQUIREMENTS FOR DIGITAL RADAR ARRAYS v IN  0ROCEEDINGS OF THE   )%%% 2ADAR #ONFERENCE  -AY n    PP n  ' ( # VAN 7ERKHOVEN AND ! + 'OLSHAYAN  h#ALIBRATION ASPECTS OF THE !0!2 ANTENNA UNIT v  IN )%%% )NTERNATIONAL #ONFERENCE ON 0HASED !RRAY 3YSTEMS AND 4ECHNOLOGY   -AY n     PP n  * + -ULCAHEY AND - ' 3ARCIONE  h#ALIBRATION AND DIAGNOSTICS OF THE 4(!!$ SOLID STATE  PHASED ARRAY IN A PLANAR NEARFIELD FACILITY v  )%%% )NTERNATIONAL 3YMPOSIUM ON 0HASED !RRAY  3YSTEMS AND 4ECHNOLOGY     PP n  /CTOBER n    - 3COTT  h3AMPSON -&2 ACTIVE PHASED ARRAY ANTENNA v IN  )%%% )NTERNATIONAL 3YMPOSIUM ON  0HASED !RRAY 3YSTEMS AND 4ECHNOLOGY   /CTOBER n    PP n  $ 3LATER  .EAR 
 He is the author of the leading college textbook on radar, Introduction to Radar Systems (McGraw-Hill), now in its second edition, and the editor of Radar Applications. He is a member of the National Academy of Engineering, a Fellow of the IEEE, and has served as editor of the Proceedings of the IEEE. This page has been reformatted by Knovel to provide easier navigation. 
 The echo signal is shifted in frequency  by the doppler efT'ect. The form of the doppler-shifted signals at each of the two frequencies f,  and ,1; tnay be written  I 4~4-1 Ro t7,, = sin 2n(f1 +fdl)t - ----  C +  where Ro = range to target at a particular time t = to (range that would be measured if  target were not moving)  .br = doppler frequency shift associated with frequency fl  .f,, = doppler frequency shift associated with frequency f2  (3.17)CWANDFREQUENCY-MODULATED RADAR95 250ms.Aphase-monopulse technique isIIsedtoreducetheterrainbiaseffect.68Theunit weighs44pounds including radome, andrequires 165VAofpower.Itisrequired tooperate from50to1000knotsatattitudes of±25°pitchand±45°rolloftheaircraft, atanaltitude of40,000ftoverwater.Thermsaccuracy isclaimed tobewithin0.13percent ±O.1knotsof thetruegroundvelocity. 3.5l\'lULTIPLE-FREQUENCY CWRADAR 12.57-63 Although ithasbeensaidinthischapterthatCWradardoesnotmeasure range,itispossible undersomecircul11stances todosobymeasuring thephaseoftheechosignalrelativetothe phaseofthetransmitted signal.Consider aCWradarradiating asingle-frequency sinewaveof theformsin2rr!;,r.(Theamplitude ofthesignalistakentobeunitysinceitdoesnotinfluence theresult.)ThesignaltravelstothetargetatarangeRandreturnstotheradarafteratime T=2R/c.wherecisthevelocity ofpropagation. 
 67-70, June, 1956.  28. Hausz, W., and R. 
 105.  75. Hanipton, R. 
 ING IN THE INTERPRETATION OR USE OF INFORMATION BY ELECTRONIC S YSTEMS   4HE CATEGORIES  OF DECEPTION ARE MANIPULATIVE AND IMITATIVE  -ANIPULATIVE IMPLIES THE ALTERATION OF  FRIENDLY %- SIGNALS TO ACCOMPLISH DECEPTION  WHEREAS  IMITATIVE CONSISTS OF INTRODUCING  RADIATION INTO RADAR CHANNELS THAT IMITATES A HOSTILE EMISSION $%#- IS ALSO DIVIDED INTO TRANSPONDERS AND  REPEATERS  4RANSPONDERS GENERATE NONCOHERENT SIGNALS THAT EMU 
 The sine delay circuit istriggered bythebasic pulse, and thecosine circuit istriggered bythesine pulse produced bythesine delay circuit. Each. gives afinite delay Awhen thecontrolling voltage iszero. 
 This maximum area is that ofthe wgular hexagon formed bycutting offthe rorners ofthe projection ofthecorner onitsaxis ofsymmetry; itisgiven by. 68 PROPERTIES OFRADAR TARGETS A~nx =~. where aisthe edge ofthe corner. 
 One of the magnitude terms corresponds to the range resolution capability of the system; the other, to azimuth resolution. Quantitative expres- sions for the resolution in each of these coordinates will be obtained below. The resolution terms in Eqs. 
   !PRIL   ' / 3AUERMANN AND 0 # 7ATERMAN  h3CATTERING MODELING )NVESTIGATION OF SCATTERING BY ROUGH  SURFACES v -)42% #ORPORATION  2EPT -42 
 A number of different techniques have been  proposed for in-the-field calibration including  mutual coupling,111 near-field antennas,109 and  RF sampling. Mutual-coupling techniques utilize the  mutual coupling paths between adjacent array  elements for transmission of calibration signals  (see Figure 13.41 a). In this technique, a signal  is transmitted from an array element, and the  nearest elements surrounding the transmit ele - ment are used to receive the transmitted calibra - tion signal.111 The signal received is compared  to a stored reference obtained during factory  tests. 
 It should be noted that, for land clutter, a° can vary considerably from one res- olution cell to the next. A typical distribution of CT°, taken from Barton,8 is shown in Fig. 15.10. 
 163–166. 48. L. 
 ZONTAL POLARIZATION INCIDENT ELECTRIC FIELD IN THE PLANE OF THE OGIVE AXIS AND THE LINE OF  SIGHT  4HE LARGE LOBE AT THE RIGHT SIDE OF THE PATTERN IS A SPECULAR ECHO IN THE BROADSIDE SECTOR  AND THE SEQUENCE OF PEAKS AT THE LEFT SIDE IS THE CONTRIBUTION OF THE SURFACE TRAV 
 £Î°xÈ  2!$!2 (!.$"//+  ! MULTIPLE SIMULTANEOUS RECEIVE BEAM CLUSTER CAN BE FORMED IN SEVERAL DIFFERENT WAYS  )F ANALOG BEAMFORMING IS USED  THE RECEIVE SIGNALS CAN BE SPLIT  . WAYS INTO  . SEPARATE  ANALOG BEAMFORMERS %ACH ANALOG BEAMFORMER IS DESIGNED TO PRODUCE ONE OF THE  . OFFSET  BEAMS IN A BEAM CLUSTER !NOTHER WAY TO GENERATE MULTIPLE SIMULTANEOUS RECEIVE BEAMS  IS TO USE DIGITAL BEAMFORMING $"&   WHICH IS DISCUSSED IN MORE DETAIL IN THE NEXT SEC 
 POINT CIRCUIT  PARAMETERS  INCLUDING MAXIMUM AND MINIMUM  USABLE FREQUENCY  ELEVATION ANGLE  GROUP PATH  MODE PROBABILITY  PATH LOSS  AND SIGNAL 
 Any use is subject to the Terms of Use as given at the website. Ground Echo.  GROUND ECHO  16.536x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 The results were described in terms of s 0F4, which was called clutter strength .  F is a propagation factor that accounts for multipath, attenuation, etc., but could not  be measured separately. 
 ABLE FOR THE LEISURE MARKET CAN SELL FOR LESS THAN   &)'52%  3MALL BOAT RADAR #OURTESY &URUNO 53!  )NC . ÓÓ°{  2!$!2 (!.$"//+  $ETECTION 0ERFORMANCE  )N 
 [CrossRef ] 13. Tibshirani, R. Regression Shrinkage and Selection via the Lasso. 
 .d FIG.10.48.—Medium-power airborne pulser. Amode change inwhich an~ncrease involtage calls foradecrease incur- rent can cause the instability typical ofany negative-resistance load. 1 Itisofconsiderable importance that thedesigner consider theproblem of stability from thestandpoint ofthesystem asawhole. 
 The feed structure of the 15-ft by 30-ft planar array generates a full two-axis monopulse beam set on receive, consisting of a sum and two delta beams. An additional column feed provides a special low-angle height finding capability for the lowest angle beam positions. The feed generates a pair of squinted sum-type beams carefully placed in elevation and processed as a monopulse pair. 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 marine geoid.69 Geos-3 and the S-193 altimeters used conventional pulse-compression  techniques. As suggested in the table, neither of these two early altimeters included a  water-vapor radiometer, and each used only one frequency, so that they had no in-built  means to correct for ionospheric or atmospheric propagation delays. 
 332 INTRODUCTION TO RADAR SYSTEMS  One approach is to try all possible element locations with the given nunlber of elenlents  and select that arrangement which produces the best result. This technique, called rotul  c~t~~rrt~rrtlriort, is generally impractical because of the large number of possible soli~tions that  would need to be examined. An equivalent result, with less con~putation, is to apply ~lj~t~(~ttii~  proyrar)lnlirtg, a method for determining the optimum solution to a multistage problem by  optimizing each stage of the problem on the basis of the input to that stage. 
 1975, Arlington, VA, pp. 128-131, IEEE Cat. no. 
 RETURN THEORIES CAN BE EXTREMELY USEFUL 4HE VALIDITY OF ANY GROUND 
 TRACKING  ALGORITHMS BASICALLY PROPAGATE ONE HYPOTHESIS FORWARD IN TIME   RECURSIVELY CHECKING FOR hTARGET 
 BASED DUCTING CONDITIONS IS BY DIVERGENCE  SPREADING OUT  OF RELATIVELY COOL AIR UNDER A THUNDERSTORM 7HILE THIS METHOD MAY NOT BE AS FREQUENT AS THE OTHER METHODS  IT MAY STILL ENHANCE SURFACE PROPAGATION DURING THE THUNDERSTORM ACTIVITY  USUALLY ON THE ORDER OF A FEW HOURS 7ITH THE EXCEPTION OF THUNDERSTORM CONDITIONS  SURFACE 
 8.3 AUTOMATIC TRACKING Track-while-scan (TWS) systems are tracking systems for surveillance radars whose nominal scan time (revisit time) is from 4 to 12 s for aircraft targets. If the probability of detection (PD) per scan is high, if accurate target location measure- ments are made, if the target density is low, and if there are only a few false alarms, the design of the correlation logic (i.e., associating detections with tracks) and tracking filter (i.e., filter for smoothing and predicting track positions) is straightforward. However, in a realistic radar environment these assumptions are seldom valid, and the design of the automatic tracking system is complicated. 
 331–336. 53. J. 
 29 Plots of sum-beam efficiency and difference-beam slope  as a function of associated edge tapers ( H-plane shown) ch12.indd   28 12/17/07   2:31:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 
 A clutter map,  generated by the radar, is sometimes used to reduce the load on thc tracking compiltcr by  blanking clutter areas and removing detections associated with large point clutter sources not  rejected by the MTI. Slowly moving echoes that are not of interest can also be rcmoveti by the  clutter map. The availability of some distinctive target characteristic, such as its altitude, m~gtlt  also prove of help when performing track association.'' Thus, the quality of the ADT will  depend significantly on the ability of the radar to reject unwanted signals. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 22.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 There are more opportunities to enhance performance because of the fixed antenna  position; for instance, sea clutter mapping becomes easier because the antenna is not  on a moving platform. 
 COMPARISON FEED IS DESIGNED TO SENSE ANY FEED PLANE DISPLACEMENT  OF THE SPOT FROM THE CENTER OF THE FOCAL PLANE ! MONOPULSE FEED USING THE FOUR 
  
 20.1) is a solid-state, L-band, long-range, 3D air defense surveillance radar developed for the Marine Corps by the Elec- . tronic Systems Division of the General Electric Company.22 The radar is tacti- cally mobile and consists of a trailer-mounted rotating antenna and two radar shelters. The shelters house the digital signal processor, waveform generator, preprocessor, computer, peripherals, and display consoles. 
 A. H., and J. T. 
 CLUTTER IMPROVEMENT MAY BE DEFINED  AS THE FINITE SUM   ).#!'I#I I. 3#2  
 The forward projected area as well as avionics weight is very costly in most  fighter aircraft parameters. These parameters have motivated users, buyers, and  designers to want more functions in a single radar and its complementary processing  suite. As a result, most modern fighter radars are multifunctional—providing radar,  navigation, landing aids, data link, and Electronic Counter Measures (ECM) func - tions.1,2 The primary enabler for multifunctional radar is software-defined signal  and data processing, first introduced in the mid 1970s.3–6 Software programmability  allows many radar system modes to be performed using the same RF hardware. 
 Goodall: A 360° Scanning Microwave Reflector, Marconi Rel'., vol. 21. ist qtr.,  pp. 
 83. ('nritrcll. 1). 
 The peak sidelobe levels of the linear recursive sequences and of Barker codes greater  than length 5 are lower than the -13.2 dB of the linear FM waveform. However, the side lobes )  of the Barker codes can be further lowered by employing a mismatched filter and accepting a  slight loss in the peak signal-to-noise ratio. 31  Comparison of linear FM and phase-coded pu~e compression. 
 81-90, January, 1957.  57. Katz, I., and L. 
 The power in each column is shown  being distributed by a series feed to the vertical elements. If this were a parallel feed it would be  called a para/lei-parallel.feed. (Series feeds are shown here so as not to overly complicate the  figure. 
 IEEE T rans. Aerosp. Electron. 
 In statistical detection theory it is sometimes called a  type I error. The radar engineer would call it a false alarm. A type 11 error is one in which the  signal is erroneously considered to be noise when signal is actually present. 
 The tube remains  inactive until the application of the RF input pulse starts the emission process, causing  amplification to take place. At the end of the RF drive-pulse the electrons remaining in the  tube must be cleared from the interaction area to avoid feedback which generates oscillations  or noise. In reentrant CFAs, the electron stream can be collected after the removal of the RF  210INTRODUCTION TORADAR SYSTEMS amplification, thephasevelocitymustbenearthevelocityoftheelectronstream.) Abackward­ waveinteraction takesplacewhenthephasevelocity isinthedirection opposite thatofthe groupvelocity. 
 THE 
 19, p. 67, April 1987. 27. 
  D"  D" $OLPH 
 DELAY CANCELERS  THE STAGGER LIMITATION USUALLY PREDOMINATES #ONSIDER THE TRANSMITTER PULSE TRAIN AND THE CANCELER CONFIGURATIONS SHOWN IN  &IGURE  $URING THE INTERVAL  4 . WHEN THE RETURNS FROM TRANSMITTED PULSE  0. ARE  BEING RECEIVED  THE TWO 
 ( a–d) correspond to the look directions of 0◦,9 0◦, 180◦, and 270◦respectively. The black arrow represents the wind direction and the blue arrow indicates the rotation direction of the current ﬁeld. T able 5. 
 or it may be changed discretely among several predetermined values. The  number of separate pulse repetition frequencies will depend upon the degree of the multiple­ time targets. Second-time targets need only two separate repetition frequencies in order to be  resolved. 
 From  500 km, the nominal SNR is 5.4 dB, increasing to 21.3 dB at 3.0 MHz. ch18.indd   62 12/19/07   5:15:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 -   3 !PPLEBAUM  h-ATHEMATICAL DESCRIPTION OF 6)#) v 'ENERAL %LECTRIC #O  3YRACUSE  .9  2EPORT  .O !7#3 
 Lee and M. M. Bell, “Rapid intensification, eyewall contraction and breakdown of  Hurricane Charley (2004) near landfall,” Geophys. 
    X X RY RZ R§ ©¨ ¨ ¨ ¨¨¨ ¨ ¨¨¶ ¸· · · ··· · ··    WHERE RX Y Z    IS RANGE 4HE +ALMAN FILTER EQUATIONS FOR RADAR TRACKING ARE THEN  SIMPLY  GENERALIZATIONS  OF THE @  
 BEAM CLUTTER IS REJECTED BY EITHER A COMBINATION OF A DELAY 
 145-267, April, 1960.  11. Meyer, D. 
  
 IEEE 1975  111trr11utio11ul Radar COI!~~~~PIICL~. Apr. 21-23, 1975, Arlington, Va, pp. 
 CESSING GAIN IMPOSED ON THE )1 RESULTS OF THE #/2$)# )F INTEGER ARITHMETIC IS PERFORMED  AN EXTRA BIT SHOULD BE PRO 
 Operational microburst detection radars use this  automated detection algorithm with high performance ground clutter mitigation tech - niques since the phenomenon occurs near the ground and oftentimes in very light or  no precipitation. C band is the preferred operational frequency for several reasons. First, a C-band  antenna will have a smaller beamwidth than an S-band antenna of the same size  and allow improved air flow measurements with strong clutter suppression near the  airport surface. 
 The field strength at any point is inversely  proportional to the square of the range between transmitter and the point. This is called  free-space path loss . The power density, Pa , over a sphere at any point in free space is  PP G rat t=  422 p( / ) W m  (26.8) where Pt is the power radiated by the transmitter, r is the radius of the sphere, and Gt is  the transmitting antenna’s gain. 
 CIENT SPECTRAL MOMENT ESTIMATION TECHNIQUE (OWEVER  IT SHOULD BE APPLIED ONLY WHEN ONE IS CERTAIN TO HAVE A PURE WEATHER SIGNAL IN WHITE NOISE OTHERWISE  OTHER SPECTRAL COMPONENTS OR NON 
 È°ÓÈ  2!$!2 (!.$"//+  4HE PRIMARY FUNCTION OF 2& FILTERING IS THE REJECTION OF THE IMAGE RESPONSE DUE TO  THE FIRST DOWNCONVERSION )MAGE REJECTION FILTERING CAN BE ALLEVIATED USING AN IMAGE  REJECT MIXER HOWEVER  THE MAXIMUM REJECTION ACHIEVABLE BY IMAGE REJECT MIXERS IS TYPICALLY INADEQUATE WITHOUT THE USE OF ADDITIONAL REJECTION THROUGH FILTERING 4HIS IMAGE 
 Ê-/ 
 REFLECTOR ANTENNA SYSTEM OF OFFSET CONFOCAL  PARABOLOIDS  FOR SATELLITE ANTENNA APPLICATIONS v  )%%% 3YMP !NTENNAS 0ROPAG  PP n     ( + 3CHUMAN AND $ 2 0FLUG  h! PHASED ARRAY FEED  DUAL OFFSET REFLECTOR ANTENNA FOR TESTING  ARRAY COMPENSATION TECHNIQUES v )%%% 3YMP !NTENNAS 0ROPAG  PP n    7 $ &ITZGERALD  h,IMITED ELECTRONIC SCANNING WITH A NEAR 
 STATE BOTTLE  HIGH POWER LEVELS ARE GENERATED AT A  SINGLE POINT BY COMBINING THE OUTPUTS OF MANY POWER AMPLIFIER MODULES )N GENERAL   A POWER AMPLIFIER MODULE  AS SHOWN IN &IGURE   CONSISTS OF A NUMBER OF IDENTICAL AMPLIFIERS THAT ARE PARALLEL 
 Changing theprfevery10pulses,oreveryhalfbeamwidth, eliminates second-time-around clutterreturnsthatwouldnormally degrade anMTIwithpulse-to-pulse variation oftheprf. Ablockdiagram oftheMTDprocessor isshowninFig.4.27.Theinputontheleftisfrom theoutputoftheIandQAIDconverters. Thethree-pulse canceler andtheeight-pulse doppler filter-bank eliminate zero-velocity clutterandgenerate eightoverlapping filterscovering the dopplerinterval, asdescribed intheprevious section.Theuseofathree-pulse canceler ahead ofthefilter2bankeliminates stationary clutterandtherebyreducesthedynamic rangerequired 1,0 Zerovelocity filter8-pulsedoppler filterbank MagnitudeWeighting and magnitude Cluttermap -recursive ~ -J filterHitreport Figure4.27Simpleblockdiagram oftheMovingTargetDetector (MTD)signalprocessor.. 
 3.8and3.9. sSec.2.12.. 592 EXAMPLES OFRADAR SYSTEM DESIGN [SEC, 153 rwmber ofsuch surveys ofground, ship, and airborne 10-cm and 3-cm radars during the years 1943 and 1944. 
 16.2) determined by the antenna pointing angle a0, the radar sees a continuum of velocities. This results in a frequency spectrum at a particular range whose shape is determined by the antenna pattern that intersects the surface, the reflectivity of the clutter, and the velocity distribution within the beam. Furthermore, since Vr varies as a function of range at a particular azimuth i|i, the center frequency and spectrum shape vary as a function of range and az- imuth angle i|/0. 
 Unfortunately the term gain is used to denote both the peak gain and the gain as a function of  angle. Confusion as to which meaning is correct can usually be resolved from the context.  The definitions of power gain and directive gain were described above in terms of a  transmitting antenna. 
 In the AEGIS array a separate high-power amplifier feeds each of the 32  transtnitting subarrays. It is also possible to give identical phase-steering commands tosir~lilar  ele~nents in each subarray, thus allowing simplification of the beam-steering unit and of the  interface cabling between the array and the beam-steering unit. The term subarray has also  been applied to the array feed networks for producing sum and difference radiation  pattern^.'^  IIII:FlITTRONICtd,IY STlTRFD PIIASFD ARRAY ANTENNA INRADAR309 (Jr"nory !pedReflection Phase 'ihi!ler Figure8.23Reflectarray. 
   4HIS  IS A HYPERBOLA 4HE LIMITING CURVE FOR ZERO RELATIVE SPEED IS A STRAIGHT LINE  PERPENDICULAR TO THE VELOCITY VECTOR &IGURE  SHOWS SUCH A SET OF CONSTANT 
 9.6. Simple Scans.—One ofthe simple scans incommon use isthe circular (or“horizon,” or“all around looking, ”or“360”,” or“A”) scan; thebeam travels continuously around thehorizon, ormay beadjusted to scanaround atany constant angle above orbelow the horizontal. This scan iswidely used inradars providing surface-based surveillance ofland, vessels, and distant aircraft; and itisused (see Fig. 
 13, June 26, 2003. 125. M. 
 Röttger and M. F. Larsen, “UHF/VHF radar techniques for atmospheric research and wind  profiler applications,” Chapter 21 in Radar in Meteorology , Atlas (ed.) Boston: AMS, 1990,   pp. 
 J. Edwards, P. Marrone, and Y . 
 Military microwave radars  like to have available a wide spectral width for purposes of electronic protection and to  extract more detailed target information, but the increasing demands of civilian wire - less services have reduced the available spectrum available to microwave radars to the  point where it is limiting performance.) The sensitivity of microwave radars is limited by receiver noise, but the sensitivity of  HF radars is limited by external noise that enters the receiver through the antenna. This  external noise is due not only to natural mechanisms such as thunderstorms but to the sig - nals from the many HF transmitters throughout the world. Both microwave and HF radars  can be limited by the large echo signals from land or sea, though in HF skywave radars,  the problem is particularly severe. 
 The RF section consists of a 2-inch-thick honeycomb  panel with the various subsystems attached to one sur-face and a parabolic dish antenna attached to the op­ posite surface (Fig. 3).  Figure 4 is a simplified block diagram of the altimeter. 
 The Structure of ReBP-Based Scintillation Simulator Due to the shortage of space-borne P-band SAR data, the scintillation-contaminated SAR echo is required to be reconstructed from the SAR images. However, the existing method such as the inverse RDA cannot exactly accommodate the sliding spotlight observation geometry. The ReBPalgorithm [ 28] provides an efﬁcient and ﬂexible method to simulate the SAR raw data for arbitrary imaging geometry which has been validated by the real data of Sential-1 mission. 
 NOISE  POWER RATIO 3.2   0&!  AND THE BLANKING THRESHOLD  & IV  4HE PROBABILITY  0&4 OF DETECT 
 Asingle rotor winding can betapped togive the required secondary voltage. Alternatively, separate rotor windings can beused, with turns-ratios totheprimary winding chosen toprovide thecorrect output voltages. The required d-c voltages are brought out through com- mutators from the secondary windings. 
 can screen forthis purpose, desig- nated P-12,utilizes azinc-magnesium 104k. fluoride phosphor which has an exponential decay oftime constant g10’\ \between 60and 100msec (Fig. 13.4). 
 CONTROL RADARS  WHERE THE SMALLEST TARGETS OF INTEREST HAVE AN 2#3 OF ONE 
 NENT OF VELOCITY ,HERMITTE WAS AMONG THE FIRST TO DESCRIBE HOW TWO OR MORE DOPPLER  RADARS COULD BE USED  SCANNING TOGETHER  TO OBTAIN THE FULL THREE 
 At short ranges it is possible to use conventional noncoherent sidelooking radar with a  large antenna aperture and pulse compression to obtain high-resolution terrain imaging. The  images obtained with conventional noncoherent radar are generally different than those of  coherent SAR in that they are less speckled.  Inverse SAR. 
 Ithas advantages over the resolved–time-base methods when very fast sweeps areused, since there isnostarting delay such asthat introduced inpassing sweeps through asynchro. Itcanalso beadvantageously used when the scanner issoremote astomake the transmission ofsweep signals by cable difficult, and when thescan isatthesame time toorapid topermit. SEC. 
 The  frequency error will be like that of Eq. (11.20) but with the roles of B and r reversed.  The rms error in the measurement of doppler frequency with a trapezoidal pulse is  bf- (2T2/3 + 2Tt}112  -(2T2Y. 
 Figure 11.15 quantifies the impact of lost performance due to  phase or amplitude imbalance. ch11.indd   20 12/17/07   2:25:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 POLARIZED SCATTER FROM SMOOTH SURFACES IS MUCH LESS NEAR VERTI 
 , vol. GE-25, pp. 159–173, 1987. 
 The solution of the integral equations begins with the specification of the re- lation between the incident and scattered fields on the surface S, as governed by the material of which the object is made. If the body is perfectly conducting or if the electric and magnetic surface fields can be related by a constant (the surface impedance boundary condition), the equations become decoupled, and only one or the other need be solved. If the body is not homogeneous, the fields must be sampled at intervals within its interior volume, complicating the solution. 
 Some radars have to detect targets at ranges as short as the distance from behind  home plate to the pitcher’s mound in a baseball park (to measure the speed of a pitched  ball), while other radars have to operate over distances as great as the distances to the  nearest planets. Thus, a radar might be small enough to hold in the palm of one hand  or large enough to occupy the space of many football fields. Radar targets might be aircraft, ships, or missiles; but radar targets can also be  people, birds, insects, precipitation, clear air turbulence, ionized media, land features  (vegetation, mountains, roads, rivers, airfields, buildings, fences, and power-line  poles), sea, ice, icebergs, buoys, underground features, meteors, aurora, spacecraft,  and planets. 
 4(% 
 In free space, the magnetic susceptibility and electric permittivity  are constants, that is, they are independent of frequency and the medium is not dispersive.  In a dielectric with a zero loss tangent, no losses due to attenuation are encountered, and  hence there is no consideration of the attenuation, which occurs in real dielectric media. If an alternating electric field is applied to a material, the individual molecules will  be induced to rotate in an oscillatory manner about an axis through their centers, the  inertia of the molecules preventing them from responding instantaneously. 
 Skolnik (ed.). McGraw­ Hill Book Company, New York. 1970. 
 Uthe system is linear, there will be a frequency  component corresponding t9 each target. In principle, the range to each target may be  determined by measuring the individual frequency components and applying Eq. (3.11) to  each. 
 VANTAGES 0ROBABLY THE BIGGEST DISADVANTAGE IS THAT THEY REQUIRE VERY LARGE COMPUTER RESOURCES  BOTH IN TERMS OF MEMORY AND EXECUTION TIMES  PARTICULARLY FOR APPLICATIONS INVOLVING COMBINATIONS OF HIGH FREQUENCIES  HIGH ELEVATION ANGLES  HIGH TERMINALS  AND LONG RANGES )N SOME CASES  THIS COMPUTATIONAL BURDEN CAN BE REDUCED BY COMBIN 
 For example, from Eq. (1.9) it might be thought that the range  of a radar varies as All2, but Eq. (1.10) indicates a 1-'12 relationship, and Eq. 
 A paraboloid withf/D= 0.50 can be scanned ±6.5 beamswidths off axis  before the gain is reduced to 80 percent of maximum (Ref. l, p. 488). 
 126-127, May,  1952.  129. Peeler. 
 WAVE FADE 
 CESSOR COMPLEX DETECTS  ESTIMATES WAVEFORM PARAMETERS  AND RECORDS THEM FOR FUTURE USE 0ASSIVE SEARCH MAY BE COMBINED WITH CUED BURST RANGING TO BETTER ESTIMATE EMIT 
 The detailed procedures are as follows: (a) Input a single look complex (SLC) image; (b) Implement ship detection with software; (c) Select sub-images, where each sub-image includes only a single defocused ship and has the same spatial resolution as the original image; (d) Invert the sub-image to the equivalent raw data domain via an inversion method [ 26–29]; (e) Exploit ISAR processing to generate a focused image of the ship. The sub-image needs to be inverted to equivalent raw data-like data containing only the target echo, background and residual clutter. The common inversion method is known as the range Doppler inversion [ 26]. 
 Any use is subject to the Terms of Use as given at the website. Sea Clutter. 
 No doppler correlation is used since the doppler is ambiguous. The results of the first two correlations are used to blank all outputs which are likely to be sidelobe discretes from the final range correlator. Here, three range correlators are used in which the first, the A correlator, resolves the range ambiguities within some nominal range, say, 10 nmi, beyond which sidelobe discretes are not likely to be detected. 
 9.  1111. 47 56. 
 where f, is the carrier frequency and Af 2 B is the frequency excursion.  The ambiguity diagram is elliptical, as for the single pulse of unmodulated sine wave.  However, the axis of the ellipse is tilted at an angle to both the time and frequency axes. 
 CAL  AND THE RESULTING VARIATIONS MUST BE QUANTIFIED TO DETERMINE IF THE LIMITATIONS ON IMPROVEMENT FACTOR FALL WITHIN THE STABILITY BUDGET FOR THE SYSTEM (OWEVER  IF THE ONLY DIFFERENCE BETWEEN PULSES IS ABSOLUTE PHASE NOT INTRAPULSE VARIATIONS PULSE TO PULSE   SOME MITIGATION IS POSSIBLE /NE METHOD OF COMPENSATING FOR SMALL VARIATIONS IN THE PHASE OF TRANSMITTER PULSES FOLLOWS ,INCOLN ,ABORATORY CHANGED THE ORIGINAL 4$72 WAVEFORM TO AN -4$ TYPE WAVEFORM 4HE ORIGINAL 4$72 WAVEFORM WAS CONSTANT 02& DURING EACH ANTENNA ROTATION  AND PROCESSING WAS DONE WITH ELLIPTIC FILTERS  4HEY THEN MODIFIED THE SYSTEM hxTO ACHIEVE  
 ENCES   DISCUSS THE SIGNIFICANT VULNERABILITY TO %#- OF SPACEBORNE 3!2 DUR 
 Wong: Large Lateral Feed Displacements in a Parabolic  Reflector, IEEE Trans., vol. AP-22, pp. 742-745, November, 1974. 
 The generation of false targets in directions  different from that of the jammer-carrying aircraft requires injecting pulse-jamming  signals into the radar’s sidelobes. Many radars employ the SLB (see Section 24.6) to  defeat this type of ECM. True-target returns tend to fluctuate from scan to scan with fixed-frequency radars  and from pulse to pulse with frequency-agility radars. 
 BANDWIDTH PRODUCT  THIS FORM OF STRUCTURE CAN PRODUCE A TUBE OF MUCH SHORTER  LENGTH SO THAT THERE CAN BE SUBSTANTIAL SAVINGS IN MAGNET WEIGHT AND POWER 3YMONS   THE INVENTOR OF THE CLUSTERED 
 To form the doppler filters, 2048 pulses are coherently integrated. TABLE 4.6  Notional Subsystem Phase Noise Allocation SubsystemAllocationAdjustment for  Common Source [dB] Requirement [dBc/Hz] Percentage dB Transmitter 20.0% −7.0 0.0 −128.6 ExciterAM 12.5% −9.0 0.0 −130.6 PM 37.5% −4.3 −3.0 −128.9 Reciver 20.0% −7.0 0.0 −128.6 Synchronizer 10.0% −10.0 −3.0 −134.6 System 100.0% -121.6 TABLE 4.7  Discrete Level Requirement Calculation Parameter Value [dB] Units Comment Thermal Noise Power at A/D −60.0 dBc 12-bit A/D (sign +11 bits) thermal noise  set at 1.414 quanta Total  Integration  GainNumber of Pulses  Coherently Integrated33.1 dB 2048 IPPs integrated per CPI Dopper Filter Weighting −2.66 dB 90 dB Dolph-Chebyshev weighting loss Number of CPIs  Noncoherently  Integrated3.82 dB PDI of 3 CPIs per Look 10 log10(Npdi0.8) Thermal Noise Power at CFAR −94.3 dBc Effective noise level after integration Discrete to Thermal Noise Margin −4.0 dB Provides low PFA due to discretes Independent Discrete Requirement -98.3 dBc Common Discrete Requirement -101.3 dBc 3 dB less than Independent Discrete ch04.indd   30 12/20/07   4:52:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Afew simple considerations can besetforth but thereal answer can only result from careful test inawind tunnel. Although, from anelectrical viewpoint, the circular cylinder isthe most desirable shape foraradome, aerodynamically itisobjectionable due toitshigh drag. Bystreamlining acylinder itsairresistance can be reduced toasixth orless. 
 ING CLIMATIC AND WEATHER CONDITIONS ,HERMITTE  AND 5IJLENHOET ET AL THOROUGHLY  REVIEW THE EVOLUTION OF ANALYTIC EXPRESSIONS FOR DROP 
 He also describes a "time­ critical .. design, which requires some form of adding device per element, that reduces the time  to 50 to 100 11s. The better the hardware the less can be the computation time. 
 W.: Tracking in an Air Traffic Control Environment, chap. 30 of" Radar Techniques for  Detection, Tracking and Navigation," W. T. 
 Skolnik (ed.). McGraw-Hill  Book Co., New York, 1970.  59. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.6  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 SAR images are degraded by a multiplicative self-noise known as speckle , which is  a direct consequence of the coherence required by the radar-processor combination  to form the synthetic aperture and the resulting enhanced resolution. 
 Tile constant K is the average gain of the delay line canceler (K = 2 for  a two-pulse canceler arid 6 for a three-pulse catlceler.) The combined improvement factor for  I3PCA arid the sibelobe lirnitation is  Adaptive array antennas may be employed to compensate for platform motion in an  AMTI radar.6' The full array is illilrninated otl transmission so that the transmit pattern is the  sarne from pulse to pulse. On receive, tlie array is made adaptive by obtaining a separate  output from each element. Each element output can be weighted separately and the outputs  added together to form an aperture illurnir~ation function that adaptively permits motion of  tlie antenna phase center so as to compensate for platform motion. 
 SHADOWING FUNCTION AFTER DATA FROM  ) - (UNTER AND 3ENIOR Ú )%%%  AND ( 3ITTROP  . £x°Óä  2!$!2 (!.$"//+  !T THE OTHER END OF THE POTENTIALLY USEFUL RADAR SPECTRUM  IN THE MILLIMETER 
 Equation (25.1), with (RjRA)max = K» ^s *ne maximum- range oval of Cassini. It can be used to estimate the signal-to-noise S/N power ratio at any RT and RR simply by dropping the "max" and "min" designation lor (RTRR) and S/N respectively. Then when Eq. 
 BIGUOUSLY ASSOCIATED WITH IT 4HE SURFACE DESCRIPTORS GENERALLY USED IN CONNECTION WITH SEA CLUTTERSEA STATE  WIND SPEED  AND ITS ASSOCIATED EQUILIBRIUM WAVEHEIGHTARE GIVEN IN 4ABLE   WITH THE WIND SPEED IN KNOTS  THE SIGNIFICANT WAVEHEIGHT IN FEET  AND THE DURATIONFETCH REQUIRED FOR A FULLY DEVELOPED SEA IN HOURSNAUTICAL MILE )T IS OF INTEREST TO NOTE THAT THE MEDIAN WIND SPEED OVER THE WORLDS OCEANS IS ABOUT  KT  CORRESPONDING TO SEA STATE  "REAKING 7AVES AND /THER 3URFACE $ISTURBANCES  4HE OBSERVABLE FEATURES OF  THE SEA SURFACE THAT BEST SUGGEST AN ORIGIN FOR THE SHARP LOCALIZED RADAR RETURNS CALLED  SEA  SPIKES ARE SURFACE EVENTS THAT ARE THEMSELVES SHARPLY LOCALIZED  EVENTS INCLUDING BREAK 
 11.Mendel. J.T.:HelixandCoupled-Cavity Traveling-Wave Tubes.Proc.IEEE.vol.61,pp.280-298. March. 
 #ENTER !NTENNA $0#!  TECHNIQUE 3TAUDAHER   4HEY  DEVELOPED A PROCEDURE FOR 3!2 PROCESSING USING AN ARBITRARY NUMBER OF SUBAPER 
 Skolnik, M. I.: Theoretical Accuracy or Radar Measurements, IRE Trans., vol. ANE-7, pp. 
 TO 
 Observations and measurements areaided byvarious indices. Prac- tically allthedisplays that include range areprovided with asetofpre- cisely timed ‘‘electronic markers” which occur atconvenient regular intervals onthedisplay itself. These aresometimes supplemented bya manually controlled continuously movable marker, which removes the necessity forinterpolation. 
 79.Rhodes. D.R.:"Synthesis ofPlanarAntenna Sources." OxfordUniversity Press.London. 1974. 
 PLANE IMAGE WITH  C G   CONSTANT    CCR MAY BE PRODUCED 'ROUND 
 DIMENSIONAL  OR ONE 
 PERTURBED ,&- CHIRP SIGNALS AND $2&- REPEAT  JAMMER PENALIZER v )%%% 4RANS  VOL !%3n  NO   PP n  *ANUARY   0 (YBERG  h!SSESSMENT OF MODERN COHERENT JAMMING METHODS AGAINST SYNTHETIC APERTURE RADAR  3!2  v 0ROC OF %53!2   %UROPEAN #ONF ON 3YNTHETIC !PERTURE 2ADAR   &RIEDRICHSHAFEN   'ERMANY  -AY n    PP n  # "OESSWETTER  h%##- EFFECTIVENESS OF A LOW SIDELOBE ANTENNA FOR 3!2 GROUND MAPPING v  !'!2$ !60 3YMP h-ULTIFUNCTION 2ADAR FOR !IRBORNE !PPLICATIONS v 4OULOUSE  . Ó{°ÈÈ  2!$!2 (!.$"//+   ! &ARINA AND 0 ,OMBARDO  h3!2 %##- USING ADAPTIVE ANTENNAS v  0ROC OF )%%% ,ONG )SLAND  3ECTION  !DAPTIVE !NTENNA 3YSTEMS 3YMP  ,ONG )SLAND  53!  .OVEMBER   PP n  * ( %NDER  h!NTI 
 VEILLANCE FRAME TIME )N ADDITION TO THE RANGE PENALTY  THE RECEIVER WILL ALSO SUFFER INCREASED CLUTTER LEVELS AND ANGLE MEASUREMENT ERRORS $ESPITE THESE LIMITATIONS  THE "INET FLOODLIGHT RECEIVER WAS FOUND QUITE ADEQUATE FOR MEASURING THREE DIMENSIONAL VECTOR WIND FIELDS   -ULTIPLE "EAMS  ! BISTATIC RECEIVER CAN USE MULTIPLE SIMULTANEOUS FIXED RECEIVE  BEAMS TO COVER THE SURVEILLANCE SECTOR  WHICH AGAIN RESTORES THE SURVEILLANCE FRAME TIME )F THE GAIN OF EACH RECEIVE ANTENNA IS MADE EQUAL TO THE  GAIN OF THE INITIAL SINGLE  RECEIVE ANTENNA  RANGE PERFORMANCE IS ALSO RESTORED (OWEVER  THIS REMEDY INCREASES THE COST AND COMPLEXITY OF THE RECEIVER SINCE A SPECIAL BEAMFORMING NETWORK IS REQUIRED  ALONG WITH A RECEIVER AND SIGNAL PROCESSOR 230  FOR EACH BEAM 4HE MULTI 
 STATE DEVICES WILL BE APPEALING IN HIGH PERFORMANCE RADARS FOR MANY YEARS TO COME /THERS NOTE STILL THAT THE BEST VALUE IN ELECTRONIC EQUIPMENT IS PRO 
 Therefore,  when n/fp in Eq. 1.5 is replaced with its equal 4 p  ts/GΩ, the radar equation for a   surveillance radar is obtained as  RP A E n F kTF S N Lte i o n ss max( ) ( / )44 1 4= ×avσ π Ω (1.6) The radar designer has little control over the revisit time ts or the angular coverage  Ω, which are determined mainly by the job the radar has to perform. The radar cross  section also is determined by the radar application. 
 Consider an array of equally spaced elements. The spacing between adjacent elements is d, and  the signals at each element are assumed of equal amplitude. If the same phase is applied to all  elements, the relatire phase difference between adjacent elements is zero and the position of the  main beam will be broadside to the array at an angle O = 0. 
 The energy that has been lost is distributed to the sidelobes. The result - ing rms sidelobes are, therefore, σφ2 relative to the gain of a single element, as shown  in Figure 13.18. Beam-Pointing Accuracy . 
 LENGTH ON ESTABLISHING THE EFFECTIVE NUMBER OF FACETS 4HUS  THE SCATTER FROM A FACET  MAY ACTUALLY OCCUR IN DIRECTIONS OTHER THAN THAT REQUIRING THAT ANGLE OF INCIDENCE EQUAL ANGLE OF REFLECTION &IGURE  ILLUSTRATES THIS &OR LARGE FACETS COMPARED WITH WAVE 
 Tlfr: is called the  squint mode. The signal processor must be modified to account for the average doppler fre­ quency not being zero. Recorders and dis plays must bei designed to account for t lw geometry  of the offset beam. 
 The practical engineer cannot rely entirely on predictions and computations, and  must eventually measure the echo characteristics of some targets. This may be done by  using full-scale test objects or scale models thereof. Small targets often may be measured  indoors, but large targets must usually be measured on an outdoor test range. 
 This method can be used with any transmitter configuration, given an adequate LOS between transmitter and receiver. In the indirect method synchronized stable clocks are used by the receiver and (dedicated) transmitter. The receiver measures the time interval ATn between transmission of the pulse and reception of the target echo. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar.  PULSE COMPRESSION RADAR  8.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 The correlation mixer acts as a bandpass multiplier with output xin(t)xR(t). 
 (a) (b)  Figure 17. (a) NRCS contrast of eddy spirals Δσand ( b) NRCS contrast of SAR image Δσrunder different wind speeds and radar frequencies. Fifty simulations are averaged to reduce speckle bias. 
 2.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 straddling loss and would represent a single figure-of-merit for a doppler processor.  To simplify this calculation the average signal-to-clutter improvement  may be defined  as the finite sum  INCA Gi C i iN SCR= ⋅ =− ∑1 01 max, (2.22) to which the doppler straddling loss would have to be added. Subclutter Visibility (SCV)  The IEEE definition of subclutter visibility is Subclutter visibility: The ratio by which the target echo power may be weaker than coincident  clutter echo power and still be detected with specified detection and false-alarm probabilities. 
 The MOTR provides a 60° cone of electronic pulse-to-pulse beam coverage plus mechanical pedestal movement to cover the hemisphere. High accuracy and efficiency can be maintained over the ± 30° electronic-scan coverage, and this coverage moves mechanically as needed to optimally move the electronic-scan coverage along with the target con- figuration to be tracked.14'19 One- and Two-Channel Monopulse. Monopulse radars may be constructed with fewer than the conventional three IF channels. 
 LOOP FREQUENCY 
 920]INSTALLATION OFSURFACE-BASED SCANNERS 313 where they can search forand track enemy fighters approaching from the rear orother anticipated directions, orarelocated ontheturret guns. Animportant question inmounting ascanner inthebelly ofanair- plane is‘‘How farshall theantenna protrude below thekeel line?“ Too great aprotrusion will add tothe aerodynamic drag, whereas ifthe antenna isretracted toofarthevision isinadequate innearly horizontal dh-ections because ofpartial blocking ofthefield ofradiation. The ray diagram ofthe radiation field isnot asufficient guide inplanning an antenna installation. 
 2. Association of accepted detections with existing tracks. 3. 
  AND FIVE 
 MANCE STANDARDS SPECIFY THAT RADAR EQUIPMENT SHOULD MEET THE ENVIRONMENTAL REQUIRE 
 15-22, 1982. 3. Lhermitte, R. 
 This spatial distribution of energy is called scattering, and the object itself is often called a scatterer. The energy scattered back to the source of the wave (called backscattering) constitutes the radar echo of the object. The intensity of the echo is described explicitly by the radar cross section of the object, for which the abbreviation RCS has been generally recognized. 
 STATE TRANSMITTER FOR MODERN RADAR 3934%-3 v  )%%% 4RANSACTIONS ON -ICROWAVE 4HEORY AND 4ECHNIQUES   VOL   NO   PP n   $ECEMBER     $ 2UTLEDGE  . #HENG  2 9ORK  2 7EIKLE  AND - $E,ISIO  h&AILURES IN POWER COMBINING ARRAYS v  )%%% 4RANSACTIONS ON -ICROWAVE 4HEORY AND 4ECHNIQUES   VOL   NO   PP n  *ULY    , " 7ALKER   (IGH 0OWER 'A!S &%4 !MPLIFIERS   .ORWOOD  -! !RTECH (OUSE    P    (EWLETT 
 -(Z BANDWIDTH   THIS NOISE MIGHT BE  TO  D" DOWN IN CONVENTIONAL #&!S   T O  D" DOWN IN THE  LOW 
 The multiple beams may be fixed in space, steered indepen-  dently, or steered as a group (as in monopulse angle measurement). The multiple beams might  be generated on transmit as well as receive. It is convenient in some applications to generate  the multiple beams on receive only and transmit with a wide radiation pattern encompassing  the total coverage of the multiple receiving beams. 
 ‘~rt,:l.lllc I.luIId, and the lla~ Bridge. I;igllr{, 32’() illll.tr:ites tlle:ii(linr(,to~nil ionai’to]ded ))yabroad ri]-c,r f-:llle~. ‘1’he finenes.~ ofthe(Irt:iil Tvhich can be..ho\f-n depen(k (Jnthe range an(~ :tzirnlith resolution ()[the radar ::~stcnl and onthe >h:irpne~s Of. 
 GROUND ATTACK VIA FORWARD 
 BANDWIDTH PRODUCT  AND COHERENTLY PROCESSINGIN A FILTER MATCHED TO THE WAVEFORMTHE ECHO SIGNALS (IGH RESOLUTION ALONG THE TRANSVERSAL DIRECTION IS ACHIEVED BY FORMING A SYNTHETIC APERTURE 4HIS REQUIRES I  TO PUT THE RADAR ONBOARD A MOVING PLATFORM  EG  AN AIRCRAFT OR A SATELLITE II  TO RECORD THE %- SIGNALS FROM EACH SCATTERER THAT IS ILLUMINATED BY THE MOVING ANTENNA BEAM IN SUCCESSIVE INSTANTS OF TIME  AND III  TO COHERENTLY COMBINE THE SIGNALSVIA A SUITABLE AZIMUTHAL MATCHED FILTERTHUS FOCUSING THE SLIDING ANTENNA PATTERN IN A NARROWER SYNTHETIC BEAM 2ADIOMETRIC RESOLUTION  ANOTHER KEY PARAMETER  IS RELATED TO THE CAPABILITY OF 3!2 OF DISTINGUISHING DIFFERENT OBJECTS IN THE SCENE ON THE BASIS OF THEIR %- REFLECTIVITY 2ADIOMETRIC RESOLUTION DETERMINES HOW FINE A SENSOR CAN DISTINGUISH BETWEEN OBJECTS WITH SIMILAR %- REFLECTION PROPERTIES )T IS A PARAMETER OF GREAT IMPORTANCE  ESPECIALLY FOR THOSE APPLICATIONS ORIENTED TO EXTENDED TARGET EXPLOITATION LIKE POLARIMETRY AND CLASSIFICATION 4HUS   THE RADIOMETRIC RESOLU 
 A viewing visor to cut out external light could also be ﬁtted (see example in a Warwick aircraft in ﬁgure 2.14(b)). In late 1943, Indicating unit type 96 was introduced as a replacement for type 6A or 6B. This included the following improvements: four range scales of 3, 12, 30 or 120 miles; a more stable time base to reduce jitter; a range calibrator showing ¼, 1, 5 or 10 mile intervals, respectively, on the four range scales. 
 Remote Sens. 1991 , 29, 385–390. [ CrossRef ] 66. 
 The loss in the signal-to-noise ratio is based on the assumption that the transmitted amplitude spectrum is rectangular. Item 1, uniform weighting, thus provides matched-filter operation with noTAYLOR WEIGHTING'- (REFS. 39,42,43) DUALITY THEOREM". 
 AN INTRODUCTION AND OVERVIEW OF RADAR  1.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 important for meteorological purposes. These may be special radars or another  function of surveillance radars. Doppler weather radar . 
 The imaging and raw data generation procedures are formulated as I{·}∼=R−1{H{F−1{R{·}}}} , (21) G{·}∼=R{F{H−1{R−1{·}}}} , (22) whereFandF−1are the the Fourier transform pairs, His azimuth coherent addition operator and (H)−1is its inverse operation, Rreshapes the vector into matrix and R−1reshapes the matrix into a vector. 4. Real Data Experiment In this section, we will use two datasets to show the effectiveness of the proposed method. 
 74. WolfT. I.: Determination of the Radiating System Which Will Produce a Specified Directional  Characteristic, Proc. 
 Stretch is a technique related to pulse compression that permits an exchange of signal­ time duration for signal bandwidth. 58•59 Its advantage is that high range-resolution can be  obtained with wideband transmitted signals, but without the usual wideband processing circ­ uitry. However, only a portion of the range interval can be observed in this manner. 
 AIIS-H, I)]). 196 204,  March, 1972.  14. 
 W. R. East: The Microwave Propcrties of Precipitation Particles, Qirurt. 
 105. “World distribution and characteristics of atmospheric radio noise,” CCIR Rept.  322, CCIR  (International Radio Consultative Committee), International Telecommunications Union, editions  1964, 1983, and 1988. 
 Likewise all theelements whichlieinthesamerowutilizethesamephaseshifttosteerthebeamin elevation. Thephaseshiftatthe"'11thelement therefore isthesumofthephasesrequired atthe "'thcolumn forsteering inazimuth andatthe11throwforsteering inelevation. Thissumma­ tioncanbem~deatthecomputer anddistributed totheMNelements ofthearray.Alterna­ tively,At+Ncontrolsignalscanbetransmitted tothearrayifanadderisprovided ateach phaseshiftertocombine theazimuth andelevation phases. 
 ING OF GUNS  DUMB BOMBS  AND MISSILES WITH SHORT 
 SUREMENT AND ANALYSIS  THE RADAR RECEIVER AND TRANSMITTER ARE USUALLY TAKEN TO BE IN THE FAR FIELD OF THE TARGET DISCUSSED IN 3ECTION    AND AT THAT DISTANCE  THE SCATTERED FIELD % S DECAYS INVERSELY WITH THE DISTANCE  2 4HUS  THE  2 TERM IN THE NUMERATOR OF %Q   IS CANCELED BY AN IDENTICAL BUT IMPLICIT  2 TERM IN THE DENOMINATOR #ONSEQUENTLY  THE  DEPENDENCE OF THE 2#3 ON 2   AND THE NEED TO FORM THE LIMIT  USUALLY DISAPPEARS 4HE RADAR CROSS SECTION IS  THEREFORE  A COMPARISON OF THE SCATTERED POWER DENSITY AT  THE RECEIVER WITH THE INCIDENT POWER DENSITY AT THE TARGET !N EQUALLY VALID DEFINITION OF THE 2#3 RESULTS WHEN THE ELECTRIC 
 (a) Target imaging by  proposed method      ( b) Range direction profile  (c) Azimuth direction profile   Figure 24. Imaging simulation results of the strong scattering target by proposed method. According to Equations (17)–(19) in Section 3.2, we calculated that the height di ﬀerence threshold of the strong scattering target was 28.28 m. 
 SEC. 105] MAGNETRON CHARACTERISTICS 343 appreciable numbers and thus constitute well-tested designs. Fixed- frequency tubes areindicated byadotand tunable tubes byaline whose length shows the tuning range. 
 02& SPECTRUM 02&     K(Z   CONTAINS A RANGE 
 TIONS TO FILL OUT THE DESIRED VISIBILITY CRITERIA 3ECOND  THE 02& SET SHOULD ALL BE CLEAR AT THE MAXIMUM DESIGN RANGE SO THAT DETECTION LOSSES ARE AT A MINIMUM &IGURE  SHOWS ONE EXAMPLE CRITERIA FOR SELECTING THE CENTRAL 02&  IE  THE HIGH 
 -  )N .)4%3   THE !2%03 FUNCTIONALITY OF THE PERSONAL COMPUTER WAS CODED IN *AVA AND INTERFACED TO THE #OMMON /PERATING 0ICTURE #/0  4HE #/0 IS A REAL 
 [CrossRef ][PubMed ] 2. Xin, L.; Tingting, L.; Kaizhi, W.; Xingzhao, L. A novel concept of plane grid resolution for high-resolution SAR imaging systems. 
 A typical circuit for an X-band radar might have a suitable bank of adjacent two-pole filters, each 1000 Hz wide, or an equivalent set of digital filters produced by an FFT. Following each filter are a detector and a postdetection integrator whose time constant is matched to the time on target or, in the case of a tracker, the demands of the servo data rate. A threshold level is set in the circuitry following each de- tector; when this is exceeded, a voltage is generated and held until such time as it is read. 
 ELEVATION COVERAGE DEPEND ON THE SPECIFIC RADAR APPLICA 
 Mikolov, T.; Karaﬁ át, M.; Burget, L.; ˇCernock ý, J.; Khudanpur, S. Recurrent neural network based language model. In Proceedings of the Eleventh Annual Conference of the International Speech Communication Association, Makuhari, Japan, 26–30 September 2010. 
      7HERE D IS THE SPACING BETWEEN ADJACENT RADIATING ELEMENTS   K IS THE WAVELENGTH OF  THE HIGHEST OPERATING FREQUENCY  AND  P  IS THE MAXIMUM SCAN ANGLE OF THE ARRAY &OR  HEMISPHERICAL PHASED ARRAY COVERAGE  THE MAXIMUM SCAN ANGLE CAN BE UPWARDS OF   o n  DEPENDING ON THE NUMBER OF ARRAY FACES USED IN THE SYSTEM CONFIGURATION 4HUS   FOR AN 8 
 LIMITED ENVIRONMENT IS MADE &OR A SINGLE LOOK WITH  .PDI #0)S NONCOHERENTLY INTEGRATED AND A SPECIFIED  0&! PER  RANGE 
 ANGLE APPROXIMATION NO LONGER HOLDS. £Ç°Î{  2!$!2 (!.$"//+  ! NUMBER OF AUTHORS REPORT SUCCESSFUL RESULTS WITH &/0%. 3!2  USING SUCH  3!2S AS THE %NVIRONMENTAL 2ESEARCH )NSTITUTE OF -ICHIGAN 0 
  AND ANGLE 
 V . Trunk and P . K. 
 100. Sensors 2019 ,19, 1649 To deal with the problem of precise focusing of the entire image taking care the range space variant system impulse response can be addressed, in a post processing way, using one of the several available autofocusing techniques available in the scientiﬁc literature. The proposed algorithm, at the state of the art, is sufﬁcient to obtain a fair focused image. 
 THE 
 !I":iJ·;.I REFERENCES I.Ridenour, L.N.:..RadarSystemEngirieering," MITRadiation Laboratory Series.vol.I.sec.2.12, McGraw-Hili BookCompany, NewYork,1947. 2.Bachynski, M.P.:Microwave Propagation overRoughSurfaces. RCARev.,vol.20,pp.308-335, June,1959. 
 2, p. 1323. 92. 
 ~l'lius an examination of the doppler spectrum of the sea can give the sea roughness and  ditcctio~~, from wliicti cat1 hc ilifcrrcd sor~ietliirig about the witids driving tl~e sea. Swell waves  or ship eclioes can be recog~iised as distinct components. Surface currents can he noted by the  asymmetrical placement of the two resonant components about zero frequency. 
 10. Hoft, D. J., and Fuat Agi: Solid State Transmitters for Modern Radar Applications, CIE Int. 
 SIZE BUSINESS JET 4HE !IR &ORCE WEB SITE REVEALS VERY LITTLE TECHNICAL DETAIL ABOUT THE TEST CONDITIONS  ATTENDING THE DATA COLLECTION  SUCH AS THE FREQUENCY AND POLARIZATION OF THE MEASURE 
 (From Moore, Soofi, and Purduski.82) TABLE 12.3 Regression Results for Ground-Based Measurements of Snow-Covered Ground* * After Moore, Soofi, and Purduski.82 NOTE: 6 = 20 to 70°. Values of coefficients in this table also are considered those of the model. The models described above are based on averages over very large areas. 
 Sloane, E. A., J. Salerno, E. 
 ~  C 15 g  !:'.  O'  :E  '=  " 10  <::  ~  5  10 THE RADAR EQUATION 49  ~Case 4 -50% Pd  Coses 1 and 3 -50, 90, 99% Pd  Cose 5 -99% Pd  Cose 5 -50% Pd  n, = 108  100  Number of pulses inlegroted, n 1000  Figure 2.24 Integration-improvement factor as a function of the number of pulses integrated for the five  types of target tluctuation considered.  The procedure ror usirig the radar equation when the target is described by one of the  Swerling models is as follows:  1. 
 GULAR PULSE   0T IS EITHER ZERO OR THE PEAK TRANSMITTER POWER BUT FOR OTHER PULSE SHAPES   THE VARIATION WITH  T OR 2  IS SIGNIFICANT !CTUAL PULSES ARE OFTEN APPROXIMATED BY  RECTANGULAR PULSES WITH WIDTHS EQUAL TO THEIR HALF 
 Circular aperture.'.' Tlie examples of aperture distribution presented previously in this sec-  tion applied to distributions in one dimension. We shall consider here the antenna pattern  prodi~ced by a two-diniensional distribution across a circular aperture. The polar coordinates  (r, 0) are used to describe the aperture distribution A(r, O), where r is the radial distance from  the center of the circi~lar aperture, arid 0 is the angle measured in the plane of the aperture with  rcspcct to a reference. 
 While a radar engineer may like to consider refraction in terms of N-units because  it provides a better physical point of view, an AREPS user may not be a radar engineer  but a tactical operator such as a combat pilot. In graphically examining refractive gra - dients and their effect upon propagation (such as ducting described in Section 26.5),  a modified refractivity, defined as  M = N + 0.157 h for altitude h in meters an (26.5)  M = N + 0.048 h for altitude h in feet (26.6) is used in place of the refractivity. While a graphical N-unit versus height display will  show a negative slope (decreasing N-units) with height, a graphical M-unit versus  height display will show a change in slope, from positive (increasing M-units) under  standard atmospheric conditions to a negative slope (decreasing M-units) under ducting  atmospheric conditions. 
 The discussion in this section is concerned primarily with integration  pcrformcd by electronic devices in which detection is made automatically on the basis of a  thrcslioid crossing.  Integration may be accomplished in the radar receiver either before the second detector  (in tlic IF) or aftcr tile secorid detector (in the video). A definite distinction must be made  bctween tlicse two cases. 
 This is par- ticularly true for configurations that perform both pulse compression and azimuth compression simultaneously rather than with techniques that perform range com- pression and azimuth compression sequentially. The basic technology discussed in this chapter is the exploitation of synthetic aperture techniques for improving the azimuth resolution of a mapping radar to a value significantly finer than that achievable by making use of the radiated beam width. Synthetic aperture radar (SAR) is based on the generation of an effective long antenna by signal-processing means rather than by the actual use of a long phys- ical antenna. 
 loop(6)inoneofthecavitiesorbycoupling onecavitydirectlytoawaveguide. Notshownin Fig.6.1areend-shield diskslocatedateachendofthecathode forthepurpose ofconfining the electrons totheinteraction space. Thestrafls(7)aremetalringsconnected toalternate segments oftheanodeblock.They improve thestability andefficiency ofthetube.Thepreferred modeofmagnetron operation corresponds toanRFfieldconfiguration inwhichtheRFphasealternates 1800between adjacent cavities. 
 # %"'# &   '#%  " # '#    ' #")%'%"$&&    '% "$&&    '%"$&&    '% "$&&    '%   # &   #    #"'%# .   2!$!2 2%#%)6%23   È°Î 4HE BLOCK DIAGRAM SHOWN IN &IGURE  INCLUDES SENSITIVITY TIME CONTROL 34#   ATTENUATION AT THE 2& INPUT !LTERNATIVELY ADJUSTABLE 2& ATTENUATION MAY BE USED  %ITHER FORM PROVIDES INCREASED DYNAMIC RANGE ABOVE THAT PROVIDED BY THE ANALOG 
 The spectrum of a pulsed transmitter transmitting a simple rectangular pulse of length T is shown in Fig. 15.9. The spectral width of the (sin U)IU envelope is determined by the transmitted pulse width, the first nulls occurring at a frequency of /0 ± IAr. 
 11.5. The integrals in the expression for /32 [Eq. 11.16]  extend, in this instance, from -B/2 to + B/2 instead of from -co to +co.Thus the effective  bandwidth is  R/2  (211:)2 r f2(sin2 efr)/rr2f2 df  {J2 = . 
 At the high end of the band, extraterrestrial or galactic noise may be larger than that due to sferics. Receive sites in an area of extensive electrical equipment use can find human-made noise dominant. The HF band is well occupied by other users, and channel selection can be such that other transmitter emissions constitute the background "noise" level. 
 OGY IN TRANSMITTERS OPERATING AT 6(& AND BELOW 3INCE THE S  THE POWER OUTPUT CAPABILITY AMONG VARIOUS SOLID 
 VOLTAGE POWER SUPPLY SYSTEM THAT ALSO IS A SPACE FIRST 4HE (0! IS FULLY REDUNDANT $02 4HE DUAL 
 The AGC sys- tem detects the peak voltage of the sum signal and provides a negative dc voltage proportional to the peak signal voltage. The negative voltage is fed to the IF am- plifier stages, where it is used to decrease gain as the signal increases. A high gain in the AGC loop is equivalent to dividing the IF output by a factor proportional to its amplitude. 
 101. Cottony, H. V., and A. 
 The s ynthetic aperture should be determined for the region L, which is symmetric  around z=0.  L corresponds to the illumination width on the ground and is therefore the route of the Radar, while object P will be seen.  The airplane flies over L with a constant velocity v. 
 In a high-PRF radar, the range foldover may leave little clear  region in the range dimension, thus degrading target detectability. By using a lower  or medium PRF, the clear region in range is increased at the expense of velocity  foldover for high-doppler targets that are in the clutter-free region in high PRF. As  an example, Figure 4.5 shows the clutter-plus-noise-to-noise ratio in range-doppler  coordinates for two different X-band waveforms at similar altitudes and aircraft  velocities. 
 ·  The decrease in refractive indexrwith altitude means that the velocity of propagation . PROPAGATION OF RADAR WAVES 449  increases with altitude, causing radio waves to bend downward. The result is an increase in the  effective radar range as was illustrated in Fig. 
 In one e~arnple'~~ a tilt angle of 27" is taken for a 4-face array  covering from +90 to - 20" in elevation, instead of the 35.3" of Table 8.3. The reduction in  gain is 4.3 dB at tlie maximurn scan angle instead of 2.8 dB.  Donle antenna.Iz6 A novel approach to obtaining hemispherical coverage is the dome  antenna depicted in Fig. 
 This method isnot the only practical scheme for multichannel operation. Infact, inone ofthemost important existing applications of multichannel operation, the “V-beam” radar, anincrease intheamount FIG.4.1.—Principle ofV-beam height measurement. 1.Plane ofBeam Iisvertical. 
 .----~---_.- 3, 7 2,8 L....C----------'-------'----------'----'-----'-----1- 2040100120-140 £80u J? Clutlp.rr,reclral widlhIradarprf (a) lD100"0 I £u802 C GJ E60GJ>e 0 E 40 20 0 0001 001 015 ave.4,6 3 , 7 2,8 Clutterspectral widthfradarprf (h) Figure4.26Improvement factorfora3-pulse(double-canceler) MTIcascaded withan8-pulsedoppler filterhank.orintegrator. (a)Uniform amplitude weightsand(h)25-dBChebyshev weights.Theaverage improvement forallfiltersisindicated bythedottedcurve.(FromAlldrews.30). 126 INTRODUCTION TO RADAR SYSTEMS  4.6 OTHER MTI DELAY LINES  There are delay lines other than digital devices that have been used in MTI signal processors. 
 The input signal y(t) is multiplied by a delayed replica of the  transmitted Ggnal s(r - T,), and the product is passed through a low-pass filter to perform  the integration. The cross-correlation receiver of Fig. 10.3 tests for the presence of a target at  only a single time delay T,. 
 FUL GEODESY 3INCE ABSOLUTE HEIGHT ACCURACY IS NOT REQUIRED  GEODETIC RADAR ALTIMETERS CAN BE  RELATIVELY BASIC INSTRUMENTS  4HEY DO NOT NEED TO COMPENSATE FOR PROPAGATION DELAYS  HENCE THEY NEED ONLY ONE FREQUENCY  AND THEY DO NOT NECESSARILY NEED A WATER VAPOR  RADIOMETER 762  )NDEED  A SIMPLE INSTRUMENT IS PREFERRED IT HAS BEEN SHOWN THAT EFFORTS TO CORRECT FOR PATH DELAYS USUALLY ADD NOISE TO SLOPE ESTIMATES  'EODETIC MEA 
 8, pp. 17-20, September 1978. 32. 
 N.: Radar Systems with Electronic Sector Scanning, J. Brit. IRE, vol. 
   PP n  *ULY   ' $IKE  2 7ALLENBERG  AND * 0OTENZA  h)NVERSE 3!2 AND ITS APPLICATION TO AIRCRAFT CLASSIFICA 
 The sensitive time must belong enough toallow for all uncertainties intheperiodicity oftheincoming signal and forchanges in theflip-flop circuit timing. This method can also beused todistinguish between different signals which have been transmitted onatime-sharing basis: forexample, to separate pulses from video signals. Ifthe coincidence circuit istobe used todecode more than one setofpulses, theflip-flop can betriggered bythelast setorbyapulse from adelay circuit which spans thesignal interval. 
 AP-9, pp. 377-383, July, 1961.  .,o. 
 (i) Beacon coding and IFF from friendly ships or aircraft should be readable by both the pilot and the observer. (j) The equipment is to be suitable for use at heights between 50 and 15,000 ft. 3.2 Centimetric airborne radar development and trials Early work on centimetric radar for airborne use was started at Worth Matravers, near Swanage in Dorset, at the Ministry of Aircraft Production Research Establishment (MAPRE). 
 Target position information provided with complete data. Approach Channel Ball 1 Ball 2 Ball 3 Ball 4 Ball 5 Initial Traditional approach–( −0.20,−0.20) (0.20, −0.20) (0.00, 0.00) ( −0.20, 0.20) (0.20, 0.20) 1( −0.22,−0.19) (0.18, −0.18) ( −0.05, 0.02) ( −0.22, 0.19) (0.22, 0.22) 2( −0.21,−0.18) (0.18, −0.19) ( −0.03, 0.02) ( −0.22, 0.18) (0.23, 0.23) Proposed approach1( −0.20,−0.20) (0.19, −0.19) ( −0.01, 0.01) ( −0.20, 0.19) (0.21, 0.21) 2( −0.20,−0.20) (0.19, −0.19) ( −0.01, 0.01) ( −0.20, 0.19) (0.21, 0.21) T able 6. Target position information provided with compressed sampling data. 
 A final range detection and  its true range is then found as a cluster of three primitive detections having possible  ranges within an error window of two to three times the standard deviation of the  ambiguous range estimate. True Radial Velocity Determination.  For each true target detection, an unam - biguous radial velocity estimate must next be determined using a similar proce - dure to that described above for range. 
 RIAL )T IS DIFFICULT  HOWEVER  TO PREVENT DIFFRACTION OF RADAR ENERGY FROM THE TOP OF THE FENCES FROM REACHING THE TARGET OR TO PREVENT TARGET 
  MIN MOTION p   OR   WHICHEVER IS GREATER     OR   WHICHEVER  IS GREATER  o 4REND IS AN EARLY INDICATION AFTER  MINUTE  OF THE TARGETS SPEED AND DIRECTION p -OTION IS THE ESTABLISHED ASSESSMENT AFTER  MINUTES  OF THE TARGETS SPEED AND DIRECTION.   #)6), -!2).% 2!$!2   ÓÓ°£ CAN BE INITIATED !LL TRACKED TARGETS ARE DISPLAYED ON THE SCREEN WITH THEIR ASSOCIATED  VELOCITY VECTORS 4RACKED TARGETS MAY BE SELECTED BY THE USER SUCH THAT ALL INFORMATION CONCERNING THAT TARGET  INCLUDING #0! AND 4#0!  IS DISPLAYED ON THE DATA PANEL OF THE RADAR SCREEN ,OST TARGETS CREATE A VISUAL AND AN AUDIBLE ALARM  .ORMAL TERMINATION OF  TRACKING OCCURS WHEN A TARGET LEAVES THE ACQUISITION ZONE OR WHEN MANUALLY CANCELLED ! GUARD ZONE MAY ALSO BE SET UP BY THE OPERATOR 4HIS MAY BE IDENTICAL TO THE ACQUISI 
 Our Method As mentioned in Section 1, CNNs often require a large amount of data to train adequately. However, as with the SAR dataset, we do not have enough images for training. Therefore, we must do something to avoid the problem of over-ﬁtting. 
 In addition, a mismatch produces standing  waves on the feed line to the antenna. The voltage at the peaks of these standing waves  is (1 + | Γ |) times greater than the voltage of a matched line, where Γ is the voltage  reflection coefficient. This corresponds to an increased power level that is (1 + | Γ |)2  times as great as the actual incident power. 
 Cantalloube, H.; Nahum, C. Multiscale Local Map-Drift-Driven Multilateration SAR Autofocus Using Fast Polar Format Image Synthesis. IEEE T rans. 
 TIONS OF A #LASS 
 60. Varian, R. H., W. 
 In sequence, these radars had increasingly more capability in terms of incidence,  frequency, and polarization. SIR-C/X-SAR operated at three bands: C and L (USA)  and X (contributed through an international partnership with Germany and Italy). Data  from SIR-C continues in demand, thanks to its fully polarimetric multiband coverage  of a wide variety of scenes.10 The Shuttle Radar Terrain Mapper11 (SRTM) was an  outgrowth of SIR-C, using a small receiving antenna (at X and C band) mounted on  a 60-m long extendable strut, to collect simultaneous backscatter subsequently pro - cessed into topographic maps. 
 The United States Venus radar mission has the objective of providing global coverage with a resolution of 150 m. In the exploration of Titan, a satellite of Saturn, the larger distance to the earth will put a very tight limit on data rate transmission, which directly impacts mapping coverage and resolution. A radar can be placed into orbit around Saturn, and on selected orbits the spacecraft will fly by Titan. 
 4.1 1 are similar in form to the phased array antenna as described in  Sec. 8.2.  The impulse response of the transversal filter of Fig. 
 It is not used as often in modern tracking-radar applications as some of the other techniques to  be described. TRACKING RADAR (55  5.3 CONICAL SCAN  ;\ logical extension of the simultaneous lobing technique described in the previous section is to  rotate continuously an offset antenna beam rather than discontinuously step the beam be­ tween four discrete positions. This is known as conical scanning (Fig. 
 LINKS TO EITHER MISSILES ON THE FLY OR GUN DIRECTING COMPUTERS FOR THE NEXT ROUNDS 3HORT 
 They represent the initial state of knowledge concern-  ing the even& The probability that the receiver output v was caused by noise or by signal-plus-  noise is an a posteriori probability and represents the state of knowledge obtained as a result  of observing the output.  The method of inverse probability involves the use of the a priori probabilities associated  with each of the possible hypotheses which could explain the event. The a priori probabilities  are used, along with a knowledge of the event, to compute the a posteriori probabilities. 
 A. K. Fung, “A review of volume scatter theories for modeling applications,” Radio Sci. 
 57. Berrie, D. W.: The Effects of Pseudo-Random Noise Upon Radar System Performance, Aeronauticul  Systems Division, Wright-Patterson Air Force Base, Ohio, ASD-TR- 74-23, August, 1974. 
 A target is then declared in a range-azimuth cell if the new value exceeds the average background level by a specified amount. Adaptive Thresholding. The basic assumption of the adaptive thresholding technique is that the probability density of the noise is known except for a few unknown parameters. 
 REPEAT PERIOD  DAYS  WITH  A  
 HORIZONTAL ANTENNA SEPARATION !S LONG AS THE TWO  APERTURES DO NOT BOTH LIE ON THE SAME LINE OF SIGHT TO THE TARGET AREA  AN ESTIMATE OF  TERRAIN HEIGHT MAY BE MADE  BY COMPARING THE PHASES OF ECHOES RECEIVED BY THE TWO APERTURES #OURTESY OF 3CI4ECH 0UBLISHING  )NC  .   39.4(%4)# !0%2452% 2!$!2   £Ç°ÎÎ (ORIZONTAL ANTENNA SEPARATION   DLY PY GH2 N,   COS SIN   3.2    &URTHERMORE   WHEN THE PHASE MOVES THROUGH AN INTERVAL OF  O  AN AMBIGUITY OCCURS  IN TERRAIN ALTITUDE MEASUREMENT 4HE CORRESPONDING ALTITUDE DIFFERENCE IS COMPUTED BY  REPLACING C  $E  BY O IN %QS  AND  6ERTICAL ANTENNA SEPARATION NO BANKING    $HA M B I G2 N,  L    (ORIZONTAL ANTENNA SEPARATION   $HA M B I G2 N, COS SIN    LY YG    !LTHOUGH WE HAVE DERIVED THESE RELATIONSHIPS FOR A SINGLE MONOCHROMATIC PULSE  THEY  CAN BE SHOWN SEE 3ECTION  OF 3ULLIVAN AND 3ECTIONS  AND  OF #ARRARA ET AL   TO BE TRUE FOR 3!2 PIXELS ALSO  WITH K  REPLACED BY CFAVG 4HE .ATIONAL !ERONAUTICS AND 3PACE !DMINISTRATION .!3!  PERFORMED SUCCESSFUL  8# 
 RESOLUTION AND NARROW BEAMWIDTHS WITH SMALL ANTENNAS HOSTILE ELECTRONIC COUNTERMEASURES TO MILITARY RADARS ARE DIFFICULT TO EMPLOY AND IT IS EASIER TO HAVE . 
 T. Davis: Radar Sea Return-JOSS II, Nal'al Research  Laboratory Report 7534, Washington, D.C., Feb. 21, 1973. 
 M. G. Andreasen, “Scattering from bodies of revolution,” IEEE Trans ., vol. 
 TRAL SPREAD 7ITH THE ABOVE SYSTEM PARAMETERS  A RECEIVER SYSTEM THAT WILL PROVIDE THE MAXIMUM OBTAINABLE PERFORMANCE IS SHOWN IN &IGURE  !T THE OUTPUT OF THE PULSE 
 The output signal ofthe coincidence tube is applied tothecathode oiadiode, whose plate potential issetbytheAGC level control. Thus, ifthe signals from the coincidence tube are suff- iciently negative tocause the diode toconduct, thegrid ofthecathode follower which isalso connected tothe plate ofthe diode will change potential and thereby change the grid potential onthe first three i-f stages. Along time constant inthe cathode-follower grid circuit holds the grid potential essentially constant between pulses. 
 The condition given by Eq. ( 14.10) is optimistic in that there are at least two factors which  result in the right-hand portion heing red·uced. One such condition results rrom the use or  actual antenna patterns rather than idealized patterns. 
 B. Hoffman and B. L. 
 Because of the ex- clusion of nonuseful portions of the waveform (as it exists at the transmitter out- put terminals), Pt as thus defined may be called the effective pulse power. It is often referred to as the peak power. However, peak power more properly signi- fies the power level at the peak of the pulse waveform (averaged over an RF cycle), and pulse power is more appropriate. 
 Stripline has been used successfully, ~specially at the lower microwave  frequencies. An advantage of the parallel-line configuration is that the signal passes through  but two switches and, in principle, should have a lower insertion loss than the cascaded  digitally swfiched phase shifter described below. A disadvantage is the relatively large number  Une-by-N switch One-by-N switch  Figure R.5 Digitally switched parallel-line phase shifter with N switchable lines. 
 The receiving antenna collects the returned energy and  delivers it to a receiver, where it is processed to detect the presence of the target and to extract  its location and relative velocity. The distance to the target is determined by measuring the  time taken for the radar signal to travel to the target and back. The direction, or angular  position, of the target may be determined from the direction of arrival of the reflected wave­ front. 
 It was placed between  the receiver port of the duplexer and the receiver to safeguard against random pulses from  nearby radar equipments which were too weak to fire the conventional TR tubes in the  duplexer, but strong enough to damage the receiver. The passive TR-limiter or the diode  limiter has replaced the protector TR. Such devices are known as receiver protectors. 
 LUTION CELL SIZE )N FACT  DISTRIBUTIONS CLOSELY RESEMBLING THOSE IN &IGURE  WERE  OBTAINED MUCH EARLIER FROM SIMILAR MEASUREMENTS WITH CONSIDERABLY BROADER PULSE WIDTHS  /THER MEASUREMENTS HAVE CONTINUED TO CONFIRM THE DIFFERENCES THAT EMERGE  IN ! 
 63. (iunderson. L. 
 Swerling, “Probability of detection for fluctuating targets,” IEEE Transactions on Information  Theory,  vol. IT-6, pp. 269–308, April 1960. 
 TRATED IN &IGURE   USE THE SUM OF THE TWO FEED  &)'52%   6ARIOUS TYPES OF HORN FEEDS FOR REFLECTOR ANTENNAS &)'52%   !MPLITUDE COM 
 Any use is subject to the Terms of Use as given at the website. Radar Receivers. 6.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 FIGURE 6.10  Group delay response of lowpass filters FIGURE 6.11  Normalized impulse response of lowpass filters ch06.indd   28 12/17/07   2:03:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Note that a different correction must be applied for each range R. When  this correction is applied at each element of the synthetic array, the antenna is said lo be  focused at a distance R and all the received echo signals from a target at that range are in  phase. The angular resolution when the antenna is focused in the Fresnel region is equivalent  to that in the far field. 
 Dwelling  longer on a target redilces the data rate, and thus can degrade the overall radar performance. A  significant redirction in data rate ge~ierally is not desirable. Dependence on burnthrough as a  rn;!jor 1'C:CM tactic is questionable. 
 The tremendous expansion ofthedevelopment program can bemeasured. SEC. 1.7] WARTIME RADAR DEVELOPMENT 17 bythe fact that thepersonnel ofthe Radiation Laboratory, which had been about 40atthebeginning of1941, rose tonearly 4000 bymid-1945. 
 The two ERS SARs were  virtually identical. ERS-1 and ERS-2 enjoyed about one year of simultaneous opera - tion, organized by ESA to chase each other so that their joint repeat visit was only one  day. This lead to the accumulation of a unique data set, especially valuable for coherent  change detection measurements15 (two-pass InSAR). 
 The continuously variable PRF system also permits eclipse-free tracking, but because of the spurious-signal problem it has not received much favor. Other ranging systems do not permit eclipse-free tracking. FM ranging is not ac- curate enough to predict when eclipsing is about to occur. 
 EARTH 
 FICIENTS OF LAND  SNOW  AND ICE v )%%% 4RANS  VOL !%3 
 102, pp. 10039–10054, 1997. 81. 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°Ó COMPOSED OF THE RADAR MEASUREMENT ACCURACIES IN RANGE  AZIMUTH  ELEVATION  AND DOP 
 When a single radar is to perforii~ both surveillance and tracking, a single frequency  sotiiculicrc it1 tlic tiiitlrllc of tlic riiicrowiivc I>ii~iil riii~st be sclccted as ;i cotiiproriiise (S haritl. or  ~'crti;~ps (' or I, bands). 'I'lie coriipro~iiise frequency rnight thus be higher than would be desirctl  for- ~ci11.cli ii~id I~)wcr tIi;111 tlc~irctl for trackitig. 
 PROCESSING FUNCTIONS 4HESE RECEIVERS MUST DEFINE AN ALLOWABLE ERROR IN THEIR OUTPUTS RELATIVE TO THEIR IDEAL NONLIN 
 7  Bearing  ................................ ................................ ................................ 
 This analysis assumes that  only doppler fading contributes to independence but motion from one cell to another  also adds independent samples. Thus, the total number of such samples is approxi - mately the product of the number calculated from Eq. 16.13 and the number of ground  cells averaged. 
 F. Shaeffer, and M. T. 
 UCT SPECIFICATION IS INTRODUCED AND FORMALLY PUBLISHED IN THE /FFICIAL *OURNAL OF THE %UROPEAN #OMMUNITIES  THE %-# $IRECTIVE SHOULD BE APPLIED  !LL EQUIP 
 But the half-power definition is customary and acceptable for use in the range equation. The range equation can be written with the product P/r replaced by the pulse energy Ef. The more detailed notation is used here because, for ordinary pulse radars, Pt and T are usually given explicitly and Et is not. 
 Also, most importantly, nearly 360 °of continuous coverage could be obtained with a rapid update rate and much improved angular resolution. As discussed in chapter 4, it was assumed that the Germans would soon introduce a warning receiver that operated at wavelengths around 9 cm and further improvements were sought to counter that possibility, resulting in ASV Mk. VI. 
 For convenience ofcomparison, thetwo echoes areusually presented on the same scope; they can beidentified ~~ith the corresponding antenna byeither oftwo arrangements-the K-scope orthe L-scope. The K-scope (Fig. 6.4a) issoarranged that the range sweeps corresponding tothetwo antennas start from different origins, with theresult that the echoes tobecompared are side-by-side. 
 BAND ELECTRONIC SCAN PHASED 
 Skillman, W. A.: "Radar Calculations Using the TI-59 Programmable Calculator," Artech House, Norwood, Mass., 1983, p. 308. 
 ;= 
 As can be seen, the asteroid’s ISAR amplitude image is of satisfactory quality, but noise still remains, the asteroid’s silhouette is satisfactorily depicted. Further improving of the ISAR image quality can be achieved by increasing the number of coherent summations which is limited by a huge processing time and graphical properties of the software on which the experiment is carried out. 8. 
 Parameters of electromagnetic simulation system. Parameter Parameter V alue Carrier frequency 10 GHz Bandwidth 6 GHz Sampling point number of frequency 512 Azimuth accumulation angle 51◦ Sampling point number of direction 71 * 17 Pitch angle 0.07◦ Figure 10. 3-D CAD model of Backhoe. 
 JO  FT AT FREQUENCY  
 Ferrites have been derived principally from two basic metal-oxide families: the ferrimag-  netic spinels and the garnets. Both have been used for microwave phase shifters. A typical  spinel ferrite is NiFe,O, . 
 where z = distance along the aperture and E(4) = field-intensity pattern. If only that portion of  ttie aperture distribution which extends over the finite-aperture dimension d were used. the  resulting antenna pattern would be  . 
 The radar equation states that if long ranges are desired, the transmitted  power must be large, the radiated energy must be concentrate<I into a narrow beam (high  transmitting antenna gain), the received echo energy must be collected with a large antenna  aperture (also synonymous with high gain), and the receiver must be sensitive to weak signals.  In practice, however, the simple radar equation does not predict the range performance of  actual radar equipments to a satisfactory degree of accuracy. The predicted values of radar  range are usually optimistic. 
 61. Pannell, J. H., J. 
 31. J. R. 
 One advantage of a storage tube  compared to an acoustic delay line is that it can be used with different pulse repetition  frequencies. That is, a constant prf is not needed. The matching of the delay time and the pulse  repetition period is not critical as in an acoustic line because the timing of the transmitter  pulse starts the sweep of the storage tube. 
 14). FlG. 19.5 This semiactive-seeker block diagram of a baseband conversion system is represen- tative of the early-generation systems in which the rear (reference) and front signals are mixed directly to extract the doppler-shifted target signal. 
 STATE DEVICES AT A REASONABLE COST 4HE DECISION TO USE A HIGH TRANSMITTER DUTY CYCLE  HOWEVER  HAS SIGNIFICANT IMPACT  ON THE REST OF THE RADAR SYSTEM /PERATION AT A HIGH DUTY CYCLE GENERALLY REQUIRES THE USE OF PULSE COMPRESSION TO PROVIDE THE DESIRED UNAMBIGUOUS RANGE COVERAGE TOGETHER WITH REASONABLY SMALL RANGE RESOLUTION /THER CONSEQUENCES FOLLOW IN TURN THE WIDE TRANSMITTED PULSE USED WITH PULSE COMPRESSION BLINDS THE RADAR AT SHORT RANGES  SO A hFILL 
 J. Fouts, S. Ekestrom, and C. 
 Croney. J.: Clutter and Its Reduction on Shipborne Radars. J11ternatio11al Conference 011 Radar  Pr!'se11t and F11wre. 
 F. Gabriel, “Spectral analysis and adaptive array superresolution techniques,” Proc. IEEE ,  vol. 
 CIRCUITED LENGTH )SOLATION IN EXCESS OF  D" IS REQUIRED )T IS CLEAR THAT THE INSERTION LOSS OF TIME 
 FORMING NETWORK #ERTAIN CROSSED 
 22.7 Total dose versus shielding thickness for a 5-year mission.32 Clutter I Interference. SBR performance is significantly dependent upon clut- ter and interference, either intentional or unintentional. To illustrate the magni- tude of the clutter problem, consider the ATC radar described in Sec. 
 Much of the literature on filter synthesis describes linear-phase filters,  but for MTI applications linear phase is of no importance. Almost identical filter  responses can be obtained with nonlinear-phase filters that require fewer pulses, as  shown in Figure 2.38. Because only a fixed number of pulses is available during the  time on target, none should be wasted. 
 Cost considerations can severely limit the length of test  programs and thereby the range of scenarios used. Radars under type approval are typi - cally installed on a trial vessel for such tests or use a land site overlooking the sea. This scenario is becoming increasingly unsatisfactory as advances in requirements  for safety and the protection of the environment mean that it is necessary to ensure that  type approval is consistently applied and is, therefore, measured in a quantitative man - ner. 
 Anal. 2016 ,41, 436–469. [ CrossRef ] 15. 
 nonscanning case is shown as Wn = O. The improvement factors were computed for the 20-wavelength aperture patterns shown in Fig. 16.17. 
 462 INTRODUCTION TO RADAR SYSTEMS  ::x:::  0  X: -L  C, w  E  0 '-'+- C 100 <1)  <lJ  U'I  "' 0  QJ  L :,  0  L  QJ a.  E  <lJ ....  .;:;  L)  D 10 a. 
 K. Moore, “Meteorological radar observations from mobile platforms,”  Chapter 22 in Radar in Meteorology , Atlas (ed.), Boston: AMS, 1990, pp. 287–322. 
 This allows asimple cure forapractical difficulty that is frequently encountered with this type ofcell. Because thereflecting end cellisloaded ononeside only, aslight smudge orspot ofscum will unload aportion ofthe crystal area without removing the electrical excitation. When this happens, the pass band exhibits sharp spikes atthe resonant frequency ofthequartz. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar.  GROUND PENETRATING RADAR  21.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 that the peak signal output to mean noise ratio is greater than can be achieved with any  other linear filter. 
 21.Miller,R.E.,T.G.Phillips, D.E.Iglesias,andR.H.Kneer:NoisePerformance ofMicrowave GaAs F.E.T.Amplifiers atLowTemperatures, Electronics Letters.vol.13,no.I,pp.10-11.Jan.6,'1977. 22.Mumford, W.W.:ABroadband Microwave NoiseSource,BellSystemTech.J.,vol.28,pp.608·-618, October, 1949. 23.IEEEStandard 686-1917: "IEEEStandard RadarDefinitions," Nov.9,1977.. 
 $OMAIN &$4$  METHODS CAN BE USED TO MODEL THE FIELD  PROPAGATION OF A TYPICAL '02 SYSTEM 4HE ANTENNA USED FOR THIS PURPOSE IS A RESISTIVELY LOADED 4%- HORN  AS DESCRIBED BY -ARTEL ET AL  )T IS  CM LONG WITH AN APERTURE OF   CM BY  CM 4HE 4%- HORN HAS ULTRAWIDEBAND CAPABILITIES FROM  -(Z TO  '(Z )T IS POSITIONED ABOVE A METALLIC TARGET BURIED IN THE GROUND AS SHOWN IN &IGURE  4HE DISTANCE BETWEEN THE HORN APERTURE AND THE AIR 
 Some form of adaptation to maneuvers is required.76 The Kalman filter is sophisticated and  accurate, but is more costly to implement than the several other methods commonly used for  the smoothing and prediction of tracking data. 77 Its chief advantage over the classical a-fi  tracker is its inherent ability lo take account of maneuver statistics. If, however, the Kalman .. 
 Any use is subject to the Terms of Use as given at the website. The Radar Transmitter.  THE RADAR TRANSMITTER  10.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 Because the CFA has relatively low gain, it is sometimes used only in one or two  of the highest-power stages of an amplifier chain, where it may offer an advantage in  efficiency, operating voltage, size and/or weight compared to other tubes. The output- stage CFA might be preceded by a medium-power TWT that provides most of the gain  of the total amplifier chain. 
 I II 3A_2X >.0A2A3A4A5Asins6d d d d d ddd (b) oA2A3A4>'5A d dddd (c)sin¢Figure7.23(a)Radiation pattern £(cP)withsampled valuesA./dradians apart,whered=aperture dimen­ sion;(b)sampled values£.(n).jd), whichspecifytheantenna patternof (a);(c)reconstructed paltern£a(lji) using(sin1jJ)!t/Jcomposing function toapproximate thedesiredradiation' pattern£(cP). theorytoconstruct thetimewaveform fromthesampled values.Theantenna pattern IS givenby./ E(¢)=fE(nA)sin[n(dIA)(sin ¢-n~Hn a n=-oo 3dn(dIA)(sin¢-IlAld)(7.26) thatis,theantenna patternfromafiniteaperture isreconstructed fromasumof(sint/J)N composing functions spacedAidradapart,eachweighted according tothesamplevalues Es(llAld),asillustrated inFig.7.23c. The(sint/J)!t/Jcomposing function iswellsuitedforreconstructing thepattern. 
 BEAM ANTENNAS 7HEN THE TARGET IS AT LOW ALTITUDE  THE MULTIPATH ERRORS ARE SEVERE  AS OBSERVED IN  THE MEASURED DATA SHOWN IN &IGURE  4HIS DATA IS THE MULTIPATH ERROR OF A  BEAMWIDTH 3 BAND  
 TION MODES &)'52%   0REDICTED RANGE DEPENDENCE OF METEOR ECHO STRENGTH COMPARED WITH MEASUREMENTS GROUND  CLUTTER RETURNS ARE ALSO SHOWN 4HE DISTRIBUTION OF METEOR RADIANTS DETERMINES THIS VARIATION #%'#$ &$ $&#  &%%#$%# &%  $    ! (# 
 V . Trunk, B. H. 
 13.4~. therefore, are drawn  for each separate set of data. (A siniilar set could be drawn for (b).) There is also a saturation  efTect evident when the three sets of data are considered separately, but it is not as  pronounced as when the three sets of data are considered as one. 
 A.: Basic Design Considerations: Automatic Navigator AN/APN-67, IRE Trans.,  vol. ANE-4. pp. 
 TEMS HAVE BEEN PROPOSED  THEY HAVE NOT YET DEMONSTRATED THEIR PRACTICAL UTILITY p  #O 
 Modulo-2 addition depends only on the number of Is being added. If the number of Is is odd, the sum is 1; otherwise, the sum is O. The shift register is pulsed at the clock-fre- quency, or shift-frequency, rate. 
 3.5  3.4 Receiver Front End  .................................................  3.7  Configuration  .....................................................  3.7 Effect of Characteristics on Performance  ........... 
 Since ion osci:lations require's fiiiite time to develop (tens of microseconds), a pulse-  doppler radar with a pulse width of leis than 10 ps should not experience this form of noise.  Intermediate-frequency receiver. Thd ieceiver of the simple CW radar of Fig. 
 * *!&%)   $! +&+) 
 IEEE T rans. Geosci. Remote Sens. 
 Subsurface  Exploration for Underground Excavation and Heavy Construction , Amer. Soc. Civ. 
 Ê/,   Ê- 
 These limiters are typically designed to limit well above the maximum  signals to be processed by the receiver. In the past, limiters were used to perform a variety of analog signal-processing  functions. Hard limiters with as much as 80 dB of limiting range were used with some  designed to limit on-receiver noise. 
 STEEPER UP  ARE USED TO RESOLVE RANGE AND DOPPLER IN A SPARSE TARGET SPACE !T LOW ALTITUDES  SIDELOBE CLUTTER  EVEN  WITH 34!0 PROCESSING  LIMITS PERFORMANCE FOR ALL TARGETS BUT ESPECIALLY OPENING TARGETS   . 
 Paradella, “The MAPSAR mission: Objectives, design, and status,” in Proceedings  of EUSAR , Dresden, Germany, ITG VDE, 2006. 29. H. 
 Short -slot hybrid junctions)  (a) Antenna Dummy load  Or~nl 1R I 1  - tubes  -7  +---7-t /  Antenno Dummy load Transmitter Rece~ver  protector  'short-slot hybrid junctions ,J d U - t ..J  1 I 1  Dual TR  tubes  Figure 9.6 Balanced duplexer using dual TR tubes and two short-slot hybrid junctions. (a) Transmit  condition; (b) receive condition. lronsm~tter  - E  may he considered as a broadband directional coupler with a coupling ratio of 3 dB. 
 284 9.12 Examples ofMechanical Scanners. 284 ELECTRICAL SCANNERS. 291 9.13 The AN/APQ-7 (Eagle) Scanner 291 9.14 Schwarzschifd Antenna. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 25.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 25.3 TRANSMIT CHANNEL PROCESSING Before digital technology became widely available, analog techniques were  employed to generate radar transmit waveforms. 
 It has been estimated that the brightness-  temperature measurement made with a radiometer operating near the water vapor absorption  line of 22 GHz, along with a measurement ofsurface refractivity, can result in an improvcrnent  in angle accuracy of almost 50 percent 'as co~npared with a surface refractivity mcasurcmcnt  alone.22 The ground-based microwave radiometer can also be used to provide a correction for  the error in time delay introduced by the atmosphere, by making briglitness-temperal~~re  measitrements near the 22-GHz water vapor absorption line and the ~O-CHL absorption line  of oxygen." J  If no other information is available, a correction for the elevation angle can be had on the  basis of the yearly statistics of the meteorological data that enters into Eq. (12.9) for determin-  ing the index of refra~tion.'~  It is possible to automate, by means of a computer, the necessary calculations for deter-  mining the refractive effects of the atmosphere on the coverage of the radar. Such computa-  tions could be made at the radar site to provide the operator with the information needed to  know how a radar is affected by the natural environment. 
 Zhang B.; Hong W.; Wu, Y. Sparse microwave imaging: Principles and applications. Sci. 
 METEOROLOGICAL RADAR  19.476x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 142. J. McCarthy and R. 
 E. N. Davies: Wide Bandwidth Butler Matrix, Electronics Letters, vol. 
 TRACK DIRECTION TO FIXED ANGLES OF         AND   WITH SUFFICIENT DWELL TIME AT EACH ANGLE TO PERMIT AVERAGING TO ACHIEVE APPROXIMATELY  PRECISION 2AD3CAT DATA COLLECTED OVER THE !MAZON RAIN FOREST SUGGESTED THAT THE UNIFORMITY OF THE OBSERVED BACKSCATTER WOULD BE A STABLE CALIBRATION REFERENCE FOR SPACE 
 13, pp. 243-259,  May, 1953.  36. 
 I8 Plot of J,(I)) as a filriction of distance. (F1.0111 Sarrr~drr..~.~ IRE Tt.a~a.)  CWANDFREQUENCY-MODULATED RADAR91 harmonic ascompared withapractical CWradarbecause·thetransmitter leakage noiseis suppressed bythe11th-order Besselfunction. Thelossinsignalenergywhenoperating withthe }JBesselcomponent isreported9.J5.54tobefrom4to12dB.Although twoseparate transmit­ tingandreceiving antennas mayheused,itisnotnecessary inmanyapplications. 
 Maximum power is in the direction of the axisofthebeam.Powervaluesdiminishrapidlyindirectionsawayfromtheaxis.The beam width in this case is taken as the angle between the half-powerpoints. For a given amount of transmitted power, the main lobe of the radar beam extends to a greater distance at a given power level with greaterconcentration of power in narrower beam widths. To increase maximumdetection range capabilities, the energy is concentrated into as narrow abeam as is feasible. 
 In other designs the scan is  saw-tooth with the beam sweeping across the plane of scan and then stepping back almost  instantaneously to its starting point. The saw-tooth scan is generally preferred in radar applica­ tions. Such antennas would be used where a small angular sector needs to be covered with a  rapid scan rate. 
 The transmitted and received spectra then appear asinFig. 5.8with the two receivers receiving ~0and .fO+~,byleakage. 140 C-W RADAR SYSTEMS [SEC37 and jOf~D,jO+j,f$Dr,from the target, with ~Dand ~D~very slightly different because ofthe difference intransmitter frequencies. 
 31. Fawcette, J.: Large Radar Satellite Proposed, Microwave Syst. News, vol. 
 IEE. vol. Ill, pp. 
 T. Mal’tsev, V . M. 
 84, no. 9, pp. 1593–1623,  September 2004. 
 Operation in the region of the sink, however, is not always desirable since itahas poor fre-  quency stability. Poor pulse shape and mode changes might result. The low-power region,  where the magnetron is lightly loaded, is called the atltisitlk or opposite-si~lk region. 
 CW AND FREQUENCY-MODULATED RADAR 93  frequency is.f~ = 2(10/c)v cos r, where/~ is the carrier frequency, vis the aircraft velocity, and c  is the velocity of propagation. Typically, the depression angle}' might be in the vicinity of 65 to  70°. A single antenna beam from a doppler radar measures one component of aircraft velocity  relative to the direction of propagation. 
 L.: Relativistic Considerations of Doppler Shift, IRE Trans., vol. ANE-6. p. 
 I'lie MTI design is further cornplicated if tile moving chaff appears in the same  resolution cell as stationary surface clutter. The MTI must then be made to cancel simulta-  neously both stationary surface clutter and moving volume clutter. High range and angle  resolutiori is another technique effective in reducing the amount of clutter with which the  target must conipete. 
 The choice of transmission medium is generally a function of many parameters, including peak and average power-handling capability, operat- ing frequency and bandwidth, mechanical packaging constraints, and, of course, the overall loss that can be tolerated. More often than not a combiner design uti- lizes a hierarchy of cascaded designs to sum the outputs of many modules;10 however, unique configurations that sum many ports to a single port have been built.19'20'21 Solid-State Transmitter Design Examples AN/TPS-59. The AN/TPS-59 (Sec. 
 OF 
 RANGE SYSTEM WITH A  PRIMARY MISSION TO DETECT AND TRACK SEA 
 SCALE !LTHOUGH !$ CONVERTERS CAN OFTEN HANDLE MODEST OVERLOAD WITH FAST RECOVERY  THE DISTORTION THAT OCCURS DEGRADES SIGNAL PROCESSING SUCH AS DIGITAL PULSE COMPRESSION AND CLUTTER REJECTION 7ITH )& LIMITING  THESE HARMONICS ARE FILTERED OUT USING BANDPASS  FILTERING AFTER LIMITING PRIOR  TO !$ CONVERSION  MINI 
 COVERED  SALINE ICE v 0ROC )'!233  VOL   PP n    * " "ILLINGSLEY   ,OW 
 I E IIII <1 IIII I I I direction theantenna mustbemovedinordertoaligntheswitching axiswiththedirection of thetarget.Whenthevoltages inthetwoswitched positions areequal,thetargetisonaxisand, itsposition maybedetermined fromtheaxisdirection. Twoadditional switching positions areneededtoobtaintheangularerrorintheortho­ gonalcoordinate. Thusatwo-dimensional sequentially lobingradarmightconsistofacluster offourfeedhornsilluminating asingleantenna, arranged sothattheright-left, up-down sectorsarecovered bysuccessive antenna positions. 
 1973. IJJ.Kummer. W.H.(ed.):SpecialIssueonConformal Arrays,IEEETrailS.,vol.AP-22.no.t.January, 1974.. 
 Conclusions Focusing on the near-ﬁeld ISAR imaging, this paper puts forward an interferometric near-ﬁeld 3-D imaging approach for joint sparsity reconstruction. Since scattering characteristics of targets in different channels are effectively made use of in joint sparsity, the imaging results feature a combination of interferometric processing and sparsity optimization. In addition to acquisition of near-ﬁeld high-resolution 3-D images with less observation echoes applied, it can also accurately reﬂect the position information of scattering points. 
 The general problem ofpower supply forground radar falls into four main groupings: 1.Fixed locations with commercial electric service available. 2.Large systems (with requirements forhighly dependable service under allconditions) atfixed locations without commercial electric service, orformobile use. 3.Small systems foruseinfixed locations without commercial power, orformobile use. 
 In order to focus the radio energy into a narrow beam thelaws of physics prevail and the wavelength must be within the fewcentimeters range. The radio-frequency energy transmitted by pulse-modulated radars consists of a series of equally spaced pulses, frequently having durations ofabout 1 microsecond or less, separated by very short but relatively longperiods during which no energy is transmitted. The terms PULSE-MODULATED RADAR and PULSE MODULATION are derived from thismethod of transmission of radio-frequency energy. 
 Evaluation of CB is discussed in Sec. 2.3. The quantity (S/N)min(0) in Eq. 
 It derives the height of a  target from the time difference between the radar signal reflected directly from the target and  the multipath signal that arrives via reflection from the surface of the earth.  Consider the geometry of Fig. 12.l for propagation over a plane reflecting surfa~e. 
 Second, out-of-plane CTB° values are not signif- icantly different (within — 5 dB) from in-plane <JBQ values for 4>< ~ 10° and <|>> ~ 140°, i.e., angles close to in-plane conditions. The 4>< ~ JO0 limit is based on Cost, Ulaby, and Domville data; the <|» ~ 140° limit, on Ulaby and Larson data. Ewell *114 measured horizontally and vertically polarized out-of-plane <JBQ for sea clutter at 0, and 0,, near grazing incidence (6,-, 0^ « 1°). 
 But with the trigger in  operation the saw-tooth form we obtain is shown thus  ye | /| / | > or, in other words, a series of  /| spaced by a time interval of L__J , which latter  is controlled by the trigger circuit.  The thyratron type of circuit is normally not suitable  for very high frequencies, and then we have to use time-  base crrcuits employing hard valves all through. There  are many such, and the radar enthusiast who wants to  probe the construction of such circuits is recommended  to O. 
 ARRAY MULTI 
 IZED FEED TO THE RADIATING ELEMENT . ££°ÎÓ  2!$!2 (!.$"//+  &IGURE  4HE TRANSMITTER PORTION OF THE 42 MODULE CONTAINS SEVEN SILICON BIPO 
 Proc. IEEE. vol. 
 With 12 cm of wet snow, a0 decreased approximately 5  to IO dB at grazing angles between 30 and 80°. At 30° grazing angle, for example, the variation  of a0 as a function of the water content of the snow is in the range -0.3 to -0.6 d B/0.1 g/cm 2  over the frequency range from L to C bands. Other measurements indicate that the presence of . 
 / 
 A klystron can be operated over a fairly wide range of beam voltage without a large  change in the gain characteristics. However, high-power traveling-wave tubes tend to oscillate  at reduced beam voltage. Therefore the tolerance on the TWT beam voltage must be tighter  witli increasing batidwidtti.' The protection requirements for traveling-wave tubes aresimilar  RADAR TRANSMITTERS 207 QKW-I723 TWTs,eachwithapeakpowerof175kWandanaverage powerofto.5kW operating overthefrequency bandoffrom1175,toI375 MHz.Sincethisradarisdesigned to monitor ballistic-missile reentryvehicles, itspulsewidthisasgreatas2000Jls. 
 Either form of monostatic radar avoids the costs of multiple sites and asso - ciated communications infrastructure, and the challenge of finding suitable sites with  an appropriate geographical relationship, but they are constrained in waveform choice  and/or radiated power by the need to avoid simultaneous transmission and reception,  as well as being potentially susceptible to range-folded clutter. In particular, the class  of FM-CW waveforms has been widely adopted, driven mainly by constraints on spec - tral emissions outside the nominal radar bandwidth. For these reasons, configurations  employing separate transmit and receive antenna sites are employed in radars such as  Jindalee, JORN, and ROTHR, usually in a quasi-monostatic arrangement where the  ch20.indd   24 12/20/07   1:15:39 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Chan et al., “Experimental studies of bistatic scattering from two-dimensional conducting  random rough surfaces,” IEEE Trans. on Geosc. and Remote Sensing , vol. 
 This was necessary because of its poor angular accuracy. However, its  range accuracy was superior to that obtained with optical methods. The SCR-268 remained  the standard fire-control equipment until January, 1944, when it was replaced by the SCR-584  microwave radar. 
 DELAY CANCELER 4HE IMPROVEMENT FACTOR SHOWN IS THE IMPROVEMENT FACTOR FOR A POINT SCATTERER AVERAGED OVER THE NULL 
 The limited search capability of a laser meanb that \  some sort of other cueing sensor, either electro-optical and/or radar, may he needed in order  for the laser radar to acquire a target.86  The fundamental measurement capabilities of a properly dcsigtled laser radar cannot he  equalled with a microwave radar. Thus laser radars are used for those special applicat~ons  where its exceptional measurement capabilities are required, and where the need to search a  large solid-angle and all-weather operation are not important.  REFERENCES  1. 
 Dunn, J. H., and D. D. 
 The painting ofthe pip is continued until the trailing edge of the beam is rotated beyond thetarget. Therefore, the pip is distorted angularly by an amount equal to theeffective horizontal beam width.. 30As illustrated in ﬁgure 1.21, in which a horizontal beam width of 10˚ is used for graphical clarity only, the actual bearing of a small target havinggood reﬂecting properties is 090˚, but the pip as painted on the PPI extendsfrom 095˚ to 085˚. 
 These ten pulses are processed by the delay-line canceler  and the doppler filter-bank, to form eight doppler filters. Thus, the radar output is divided into  approximately 2,920,000 range-azimuth-doppler cells. Each of these cells has its own adaptive  threshold. 
 D   2#!  -ISSILE AND 3URFACE  2ADAR $IVISION  -OORESTOWN  .*  $ECEMBER    0 2 $AX  h!CCURATE TRACKING OF LOW ELEVATION TARGETS OVER THE SEA WITH A MONOPULSE RADAR v  IN )%% 2ADAR #ONF 0UBL    2ADAR0RESENT AND &UTURE   ,ONDON  /CTOBER n      PP n  $ $ (OWARD  h)NVESTIGATION AND APPLICATION OF RADAR TECHNIQUES FOR LOW 
 One of the first of these, called lobe switching, was first demon- strated in 1937 on a prototype of what later became the U.S. Army Signal Corps SCR-268 radar.4 This radar was designed for directing antiaircraft gunfire and was the first production radar to use lobe-switching techniques to center the an- tenna on the target. Two separate identical beams, one above and one below the antenna boresight, are formed at the antenna on receive. 
 Jordan, B. L. Huneycutt, and M. 
  AND %23 
 ARRAYS  AND  4O OBTAIN THE DIFFERENCE BEAM  THE ANALOGUE TAPERING AT THE ELEMENT LEVEL IS COMPENSATED  AT THE SUB 
 In other situations where  the radar may be closing on the target from the tail or from the side, the relative velocities may  be small and the target doppler will.lie within the clutter doppler spectrum. In such situations  the target echo must compete with thedutter energy for recognition. A large part of the clutter  energy may be removed with a bank of fixed narrowband filters covering the expected range of  doppler frequencies. 
 ERECTOR 
 The rise time is the time required for the output to rise from the -205 to the -S point, and the fall time is the time required for the output to fall from the -S point to the -205 point. Because of the logarithmic characteristic, the fall time tends to be a straight line and to exceed the rise time. GAIN PER SEGMENT (dB) FIG. 
 The sea surface can be represented to a good approximation as a superposition or  spectrum S( )k of surface gravity waves satisfying the dispersion relation  w k k2=g dtanh( ) (20.3)  where w is the wave angular frequency, g is the acceleration due to gravity, k  is  the wave number of the water wave, and d is the water depth. For deep water, this  reduces to  w k2=g (20.4)  from which the water wave phase velocity can be written  vgL≡ =  w k 21 2 π/  (20.5)  where L is the wavelength of the water wave. 2. 
 H., and I. Pfeffer: The Effect of AGC on Radar Tracking Noise, Proc. IRE, vol. 
 5.Daley,J.c.,J.T.Ransone, Jr.,andW.T.Davis:RadarSeaReturn-JOSS II,NavalResearch Laboratory Report7534,Washington, D.C.,Feb.21,1973. 6.Moskowitz, L.I.:TheWaveSpectrum andWindspeed asDescriptors oftheOceanSurface,N"val Research Laboratory Report7626,Washington, D.C.,Oct.30,1973. 7.Macdonald, F.c.:Characteristics ofRadarSeaClutter,ptI-Persistent Target-Like EchoesinSea Clutter,NavalResearch Laboratory Report4902,Washington, D.C.,Mar.19,1957. 
 Luo, X.J.; Survey, C. Division of “six belts and ﬁve types” of carbonate region and control of karst geological disaster in Wuhan. J. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar.  GROUND PENETRATING RADAR  21.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 Deconvolving the image using any of the following processes can do this; syn - thetic aperture processing, conjugate gradient methods, and reverse time migration are  extensively reported in the literature. 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 9.5 TARGET ACQUISITION AND RANGE TRACKING Range tracking is accomplished by continuously measuring the time delay between  the transmission of an RF pulse and the echo signal returned from the target, and con - verting the roundtrip delay to units of distance. The range measurement is the most  precise position-coordinate measurement of the radar; typically, with high SNR , it can  be within a few meters at hundreds-of-miles range. 
 van Zyl, H. Zebker, and D. N. 
 thogonal to the first one, i.e., containing the peak and the 0° elevation angle, re- sults in the so-called azimuth pattern, also a principal-plane cut because it con- tains the peak of the beam as well as one of the angular coordinate axes. These principal planes are sometimes called cardinal planes. All other vertical planes through the beam peak are called inter cardinal planes. 
 , Ê**  /" - /PERATIONAL METEOROLOGICAL RADARS ARE DESIGNED FOR RELIABILITY AND SIMPLICITY OF OPERA 
 L., and C. Cash: Polarization Agility for Radar   lint Reduction, IEEE Region 3 Corlrcrl-  rion, Huntsville, Alabama, Nov. 19-21, 1969. 
 W. H. F. 
 15.6, assuming a fully developed sea , and T ′ from Eq. 15.5. To this, there must  ch15.indd   20 12/15/07   6:17:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Although they may each be small, the sum total can result in a significant reduction in radar  performance. It is important to understand the origins of these losses, not only for better  predictions of radar range, but also for the purpose of keeping them to a minimum by careful  radar design. 62 INTRODUCTION TO RADAR SYSTEMS  2.13 PROPAGATlON EFFECTS  In analyzing radar performance it is convenient to assume that the radar and target are both  located in free space. 
 ING THROUGH THE )& LIMITING PROCESS /NE CAN SEE THAT MANY OF THE INDIVIDUAL PULSE RETURNS FROM THE TARGET EXCEED THE DETECTION THRESHOLD  WHEREAS ONLY FOUR OF THE CLUTTER RESIDUE PULSES EXCEED THE THRESHOLD 4O SUMMARIZE   4HE -4) IMPROVEMENT FACTOR IN A MAJORITY OF LIMITING CLUTTER  CELLS EXCEEDS THE AVERAGE IMPROVEMENT FACTOR OBTAINED WITH LINEAR PROCESSING   CELLS WITH POOR -4) IMPROVEMENT FACTOR CAN BE REJECTED WITH BINARY DETECTION PROCESSING AND  THEREFORE    EXCELLENT -4) PERFORMANCE CAN BE OBTAINED EVEN IN REGIONS OF CLUTTER THAT EXCEED THE )& DYNAMIC RANGE&)'52%  )MPROVEMENT FACTOR RESTRICTION CAUSED BY A LIMITER . Ó°ÈÓ  2!$!2 (!.$"//+  &)'52%   -EAN IMPROVEMENT FACTOR RESTRICTION VERSUS AMOUNT OF LIMITING AND CLUTTER  SPECTRAL SPREAD FOR A TWO 
 II 2-24 References 2-24 3 ASV Mk. III 3-1 3.1 Operational requirement for ASV in October 1942 3-1 3.2 Centimetric airborne radar development and trials 3-3 3.3 ASV Mk. III description 3-4 3.3.1 Waveform generator type 26 3-5 vii. 
 This is  called thermal noise, or Johnson noise, and is directly proportional to the temperature of the  ohmic portions of the circuit and the receiver bandwidth.60 The available thermal-noise power  generated by a receiver· of bandwidth Bn (in hertz) at a temperature T (degrees Kelvin) is  equal to  Available thermal-noise power= kTB" (2.2)  where k = Boltzmann's constant= 1.38 x 10-23 J/deg. If the temperature T is taken to bt.:  290 K, which corresponds approximately to room temperature (62°F), the factor kT is  4 x 10-21 W/Hz of bandwidth. If the receiver circuitry were at some other temperature, tht.:  thermal-noise power would be correspondingly different. 
 DUCE TWO INDEPENDENT MEASUREMENTS AND  THEREFORE  PROVIDE MORE ACCURATE RAINFALL 
 INSULATING  'A!S SUBSTRATE SUCH AS ION IMPLANTATION OR MOLECULAR BEAM EPITAXY /NCE THE &%4 HAS BEEN DEFINED  A COMBINATION OF DEPOSITED DIELECTRIC FILMS AND METAL LAYERS IS USED TO FORM THE PASSIVE COMPONENTS SUCH AS METAL 
 As discussed in Section 8.1, a frequency-domain weighting filter is generally  required following the matched filter to provide reduced time sidelobe levels, at the  cost of reduced SNR and an increase in the width of the compressed pulse. As an  example, the use of 40-dB Taylor weighting reduces the peak time sidelobe level from  –13.2 dB to –40 dB and introduces a 1.15 dB loss in SNR. The 3-dB width of the com - pressed pulse with weighting increases from t 3 = 0.886/ B to t 3 = 1.25/ B. 
 TERED FIELDS 4HIS HAS BEEN USED BOTH TO VALIDATE OTHER MODELS AND TO BETTER DESCRIBE  THE TRUE SCATTERING FROM A KNOWN ROUGH SURFACE 4HIS METHOD TENDS TO BE COMPUTATION 
 192. 30. E. 
 H.: Attnospltcric Effects on VHF and UHF Propagation, Proc. IRE, vol. 46. 
 The dish size and wavelength were chosen—on the basis ofrange, propagation factors, and beamwidth-to be12ftand 40cm, respectively. This latter value also determines the doppler band, which extends from zero toabout 1000 cps for400-mph targets. Thus weneed carry only one harmonic oftherepetition frequency. 
 The above two examples of jamming radar equations are simplifications. Other variations are possible. Clutter. 
 9 Improvement factor I versus normalized doppler offset s�e as a function of clutter  spectrum width s c FIGURE 3. 8 Effect of doppler-offset error; fr = PRF ch03.indd   8 12/15/07   6:02:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 AVERAGING LOG 
 S. Weller, “Electromagnetic scattering from large steady breaking waves,” Experiments  in Fluids , vol. 30, no. 
 BEAM ANTENNAS ALSO UTILIZE SOME HIGH 
 From the noise temperature  € Ttotal, one obtains the noise power:   € Ntotal=k⋅Ttotal⋅BN (6.13)  6.5 False Alarm Rate and Probability of Detection   Since the received of a Radar signal is always distorted by noise, for the detection of Radar  targets one can only make a compro mise between a “false alarm rate” and the probability of  detection. Crucial are the specifications of a detection threshold (figure 6.7), which are co m- pared to the measured signal and it is determined whether the signal is to be interpreted as noise or as a target.  The optimal threshold must be determined dependent upon the respective  application. 
 noise ratio for a given probability of detection and probabi­ lity or false alarm, an analysis similar to that used to obtain Figs. 2. 7 and 2.8 should he . 
 Butconsider thetwosignalsatBandC,representing targetechoesofequalamplitude. The noisevoltageaccompanying thesignalatBislargeenoughsothatthecombination ofsignal pIllsnoiseexceeds thethreshold. AtCthenoiseisnotaslargeandtheresultant signalplus noisedoesnotcrossthethreshold. 
 Kanevskii, M.B.:ThePropagation ofMillimeter andCentimeter WavesinTropospheric Waveguides ClosetotheSea,SOl'ietRadiophysics, vol.9,no.5,pp.867-875, 1966. Joseph,R.I.,andG.D.Smith:Propagation inanEvaporation Duct:ResultsinSomeSimpleAnalytic Models. RadioSciellce,vol.7.pp.433-441, April,1972. 
 25, 1978.  62. Tenenholtz, R.: Designing Megawatt Diode Duplexers, Microwave J., vol. 
 3–8. 11. E. 
 For example, even if the use of a large mechanical scanning system does not entail particular problems in easily accessible installations, or in well-equipped environments such as open-pit mines, it could turn out a strong limitation in remote regions operations. Therefore, within the ﬁeld of GB-InSAR systems, one of the most interesting lines of research is the replacement of mechanical scanning with some kind of Electronically Scanned Array (ESA). To this scope, Multiple Input Multiple Output (MIMO) radar are promising systems in the evolution of the GB-InSAR technology [ 10,11]. 
 Young,  and L. A. Hyland, Nov. 
 The narrowband filter (usually a quartz crystal type), constituting the speedgate band- width, is placed in the IF after only a nominal amount of fixed preamplifier gain, sufficient to establish noise figure. One additional conversion is used in the re- ceiver to avoid the problem of too much gain at one frequency. In the resulting two-conversion system, complexity is significantly reduced and unwanted signals FIG. 
 I.36  Index terms  Links   Radar (range) equation (Continued)  2.4  for HF OTH radar 24.3  jamming      1.9 9.29  losses in    2.46  for meteorological targets 23.2  for pulse doppler radar 17.33  for tracking 1.8  for volume search 1.8  Radar guidance of missiles 19.1  Radar range prediction:  accuracy of 2.60  philosophy of 2.2  (See also Radar equation)  Radar transmission equation 2.4  Radial velocity, measurement of 1.11  Radiometer-scatterometer 12.28  Radiometric homing 19.20  Radomes      6.44  airborne     6.46  boresight error in 6.51  and environmental effects 6.45  ground       6.47  high-temperature 6.46  junction effects in 6.48  for missile guidance 19.32  RADSCAT      12.28  Rain:  attenuation in 23.7  effect of, on sea clutter 13.23  RAMP         5.3 5.8 5.28  Range ambiguities in pulse doppler radar 17.5 17.19  Range equation ( see Radar equation)  This page has been reformatted by Knovel to provide easier navigation. I.37  Index terms  Links   Range-gate pull-off (stealer) 9.26  Range-height-angle chart 2.45  Range measurement 1.11  Range noise in tracking radar 18.43 18.57  Range prediction, procedure for 2.61  Range resolution:  in automatic detection 8.21  effect of CFAR 3.50  Range tracking 18.27  in missile guidance 19.26  Ranging noise in AMTI radar 16.28  Rank detector 8.19  RAT-31S      20.9  Ratio detector 8.15  Rayleigh region 11.5  Rayleigh target model 2.22  Receivers    1.4  A/D converter in 3.38  and amplitude uniformity 3.31  automatic noise-level control in 3.19  balanced mixer in 3.10  CFAR in      3.46  clutter map AGC in 3.18  coho in      3.16  diplex operation of 3.54  dynamic range of 3.4 3.11  and ECCM     9.18  filtering in 3.13 3.19  front end of 3.7  general configuration of 3.2  harmonics in 3.7  I/Q distortion in 3.41  This page has been reformatted by Knovel to provide easier navigation. I.38  Index terms  Links   Receivers (Continued)  1.4  IF limiters in 3.30  image-reject mixer in 3.11  local oscillators of 3.11  logarithmic devices in 3.25  matched filter approximations for 3.21  mixers in    3.8 3.22  noise in, and tracki ng radar accuracy 18.50  noise temperature of 2.31  phase detectors in 3.32  phase uniformity (Phamp) in 3.31  for semiactive missile guidance 19.35  spurious responses of mixers in 3.8 3.22  stalo stability in 3.15  STC in       3.17  Recording of radar signals 3.35  Reflection coefficient 2.36  Refractivity 2.44  Regulators 4.41  Remote sensing with SBR 22.3 22.29  Rendezvous radar requirements 22.3  Resonance region 11.5  Retrospective processing 8.33 8.34  Rotary-tuned magnetron 4.6  ROTHR        5.3  Rough surface reflec tion coefficient 2.38  S  S band       1.14 1.16  Salisbury screen 11.46  Sampled-data operation in missile guidance 19.20  SAR ( see Synthetic aperture radar)  This page has been reformatted by Knovel to provide easier navigation. 
 n°£{  2!$!2 (!.$"//+  4HE FREQUENCY MODULATION 
 ENS WITH INCREASING INPUT FREQUENCY !$# DATASHEETS SPECIFY THE  SPUR 
 Problems are not included in this book. Althoirgh the author  assigns problems when using this book as a text, they are not considered a major learning  technique. Instead, the comprehensive term paper, usually involving a radar design problem or  a study in depth of some particular radar technology, has been found to be a better means for  having the student reinforce what is covered in class and in the text. 
 Smith, “Comparison of along-track resolution  of stacked Geosat, ERS-1 and TOPEX satellite altimeters,” J. Geophys. Res. 
 The phases of the returned signals at the master unit are  compared with the phases of the outgoing signals. Since the master and the remote units are  stationary, there is no dopplcr frequency shift. The function of the doppler frequency is  provided by modulating the retransmitted signals at the remote unit in such a manner that a  1-k Hz beat frequency is obtained from the heterodyning process at the receiver of the master  unit. 
 GRID PARABOLOID 4HE ADVANTAGES ARE AS FOLLOWS   4HE MIRROR AND ITS DRIVE MECHANISM ARE THE ONLY MOVING PARTS FOR BEAM MOVEMENT 4HE FEED AND RADOME 
 Certain range-equation factors that present special problems will be considered at greater length in subsequent sections of the chapter. Transmitter Power and Pulse Length. The radar transmission equation, from which all the subsequent range equations are derived, is an equation for the dimensionless ratio Pt/Pr. 
 The ARSR-3 has iln instrurnentcd range of 200 nmi. and is required to detect a 2 rn2  cross-section target with a single-scan probability of detection of 0.8 and a false alarm proba-  bility of 10- '. The greater [lie radar range the fewer the number of radars required to cover a  specified area. 
    .IGHT 6n 
 120 HOW RADAR WORKS  shot at it by the ‘gun.’ In another type the reflector is  strongly positive, and by secondary emission produces  a counter-stream of electrons. Such Klystrons are quite  small, and often have a standard valve base to which is  attached the electron gun. The rhumbatron cavities  are formed by copper rings or discs, and to some extent  the device is tunable by a screw-plunger regulating the  capacity of the rhumbatron, affecting its volume or shape. 
 Ref. 21. See summaries in vol. 
  = FOR ITH ELEMENT IN  THE JTH GROUP 0[   ;   =      ]P P-- -IJ 
 This follows from the conservation of  energy. When we speak of antenna gain in relation to the radar equation, we shall usually  mean the maximum gain G, unless otherwise specified. One of the basic principles of antenna  theory is that of reciprocity, which states that the properties of an antenna are the same no  matter whether it is used for transmission or reception. 
 (Colrrtesy E~t~lirot~tr~erlral Research lrlsritlrl  4ichigan.)  524INTRODUCTION TORADAR SYSTEMS (a) (b) figure14.4(a)Synthetic aperture radarimageofSanDiego,California obtained withtheX·bandGEMS (Goodyear Electronic Mapping System) radar.Resolution =12m;aircraftaltitude =40,000ft(12km). Thisisamosaiccovering approximately 19by32km.(Courtesy Goodyear Aaospace alldLittollAero Service.) (b)AbendintheHuronriver(center)justeastofAnnArbor,Michigan. Notefoothall stadium (withlights)topleftcenter,andlargeorchard inupperrightcenter.Southisintheupdirection. 
 With radar carried in the air quite a number of different problems present themselves. The original airborne aircraft-interception apparatus used a diminutive form of ground radar, and - worked on about 200 Mcs, but very soon the new centi- metre technique sprang up, on the British discovery of the magnetron, and the very ingenious radar systems such as H2S came into being, using such short wave- lengths as 3 centimetres, a very far cry from the 300-metre band used by broadcasting stations.  . 
 Off-centering isprovided byproper biasing ofthe driver tubes. Adelay can beused inthe horizontal circuit toallow adistant range interval tobeexamined in detail. (Ifthis isnot arequirement, the same flip-flop can beused for both sawtooth generators. 
 • While HFSWR does not rely on the ionosphere, echoes from irregularities in the  ionosphere may appear at ranges in excess of ~100 km, Similarly, ground reflec - tions received via oblique skywave propagation may appear at ranges in excess of  ~200 km. Such echoes may be spread in doppler and can constitute a serious prob - lem for HFSWR systems. Accordingly, antennas should be designed with low gain  at higher elevation angles. 
 Frost and L. Lawrence, “Medium PRF Pulse Doppler Radar Processor for Dense Target  Environments,” U.S. Patent 4584579, 4/22/1986. 
 WAVE PROPERTIES OF THE SEA APPEAR 4HAT IS  THE CROSS SECTION IS SIMPLY PROPORTIONAL TO THE &OURIER TRANSFORM OF A SEA 
 Asimpleradartargetsuchasasmoothspherewillnotcausedegradation oftheangular­ tracking accuracy. Theradarcrosssectionofasphereisindependent oftheaspectatwhichit isviewed:consequently, itsechowillnotfluctuate withtime.Thesameistrue,ingeneral,ofa radarbeaconifitsantenna pattern isomnidirectional. However, mostradartargetsareofa morecomplex naturethanthesphere.Theamplitude oftheechosignalfromacomplex target mayvaryoverwidelimitsastheaspectchanges with respec~totheradar.Inaddition. 
 58)c ‘r‘<2rr,).. — ~fultiplc target f-msystem (Sec. 59)f,c 4f,6T >>.&Z’ C6TF-msystem (Sec. 
 ANGLEv PRINCIPLE 3!2 IMAGERY IS BASED ON A hRANGE 
 Jari. 25. 1977. 
 81. Cantrell, B. H., G. 
 both theory and ex·periment show a lack of rime-ice formation on a spherical  radome. 1 1 5 The trajectories of water droplets in the air stre~m flowing around large spheres do  not result in much impingement. Collection efficiencies might be only a few percent. 
 Ê 
 5.3. The antenna is mounted so that it can be positioned in both azimuth and  elevation by separate motors, which might be either electric- or hydraulic-driven. The antenna  bearn is offset by tilting either the feed or the reflector with respect to one another. 
 3EARCH   (273   AND  !LERT#ONFIRM !LL 
 The amount of weighting can  be chosen adaptively by sensing the peak signal levels (usually main-beam clutter)  and selecting the doppler weighting dynamically. If pulse compression modulation is used on the transmit pulse to increase energy on  target, pulse compression can be performed digitally either before or after the doppler  ch04.indd   13 12/20/07   4:52:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 8\ÊÊ-1, 
 Onthe other hand, ifgeometrical measurements orestimates are tobe made, orifplotting istobedone, itisdesirable tohave asmuch dis- persion aspossible; forsuch usethelarger sizes aredefinitely preferable. This requirement must bebalanced against theavailable space, particu- larly inairborne equipment. For many purposes even thelargest available tubes (lZ-in. 
 The red rectangles are the zoomed sub-images. The defocusing of moving ship in airborne SAR image is more evident. The Doppler rate shift induced by target motion in the airborne SAR system is greater than in the spaceborne SAR system. 
 BAND RADAR WITH  
 The Multistatic Measurement System (MMS) was installed at the United States Kwajalein Missile Range in 1980 to track ballistic missile skin echoes.14 The TRADEX L-band and ALTAIR ultrahigh-frequency (UHF) monostatic ra- dars are used to illuminate the targets, and the bistatic echoes, collected at two unmanned stations located about 40 km from the radars, are combined coherently at a central site. The system is projected to measure three-dimensional position and velocity with accuracies better than 4 m and 0.1 m/s, respectively, through- out reentry.13 Other multistatic radar concepts have been studied. They include the Doppler Acquisition System (DAS), which used multiple transmitters and receivers,61 and Distributed Array Radar (DAR) concepts, with large3 and small5 spatial separa- tion between receive sites. 
 END LIMITER IS ALSO REQUIRED IN ORDER TO PREVENT THE RECEIVER FROM BEING DAMAGED BY HIGH INPUT POWER LEVELS FROM THE ANTENNA THAT MAY OCCUR AS A RESULT OF LEAKAGE FROM THE 42 DEVICE DURING TRANSMIT MODE OR FROM INTERFERENCE DUE TO JAMMERS OR OTHER RADAR SYSTEMS 4HESE LIMITERS ARE TYPICALLY DESIGNED TO LIMIT WELL ABOVE THE MAXIMUM SIGNALS TO BE PROCESSED BY THE RECEIVER )N THE PAST  LIMITERS WERE USED TO PERFORM A VARIETY OF ANALOG SIGNAL 
 QUADRATURE POLARIMETRY  !T LEAST FOUR OF THESE INITIATIVES IMPLY SEVERAL SATELLITES  EITHER IN CONSTELLATION OR IN SERIES !LL TOGETHER  SOMETHING IN EXCESS OF  NEW 3!2S ARE BEING LAUNCHED IN THE FIRST DECADE OF THE ST CENTURY  FROM AT LEAST EIGHT DIFFERENT COUNTRIES (IGHLIGHTS OF SEVERAL OF THESE SYSTEMS ARE SUMMARIZED IN THE FOLLOWING PARAGRAPHS #/3-/ 
             
 TRACKING RADAR  9.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 target span will result in greater tracking noise in a slow AGC system, with the danger  of much higher noise with greater lag. Therefore, for overall performance, a fast AGC  is recommended. Range Noise (Range Glint). 
 364, May--June. 1977.  70. 
 Now ifforsome other system Nisgiven, together with thenew values oftheparameters listed inTable 2.2, the reader should beable toestimate Stim forthat system. The estimate will bebetter, ofcourse, the less extreme the departure from the conditions ofTable 2.2. We must emphasize, how- ever, the limited utility ofavalue ofSti. 
 (SeealsoChap.6ofref.19.) 62.Elphick, B.L.,M.J.Chappell, andR.Batty:TheMeasured andCalculated RCSofaResistive Target Model,lEE(Lolldoll) Radar-n, pp.120-124, Oct.25-28,1977. 63.Sinclair, G.:Theory ofModels ofElectromagnetic Systems, Proc.IRE,vol.36,pp.1364-1370, November, 1948. 64.Schcnstcd, C.E.,J.W.Crispin, andK.M.Siegel:Studies inRadarCross-Sections XV:Radar Cross-Sections oftheB-47andB-52Aircraft, Ulliv.ofMichigall, Radiation Laboratory Report 2260-1-T, August1954(unclassified), AD46741. 
 14, Chap. 6, and in Ref. 15. 
 Bartom D. K.: Low Angle Tracking. Microwave J., vol. 
  
 GUISH BETWEEN TARGETS AT DIFFERENT RANGES ! PARTICULAR TARGET MAY BE DETERMINED TO BE LOCATED ON A CONSTANT 
 Thorley, et al., Manual of Remote   Sensing , 2nd Ed., V ols. I and II, Falls Church, V A: American Society of Photogrammetry, 1983. 41. 
 r      WHERE ES IS THE PARTIAL PRESSURE OF WATER VAPOR IN MILLIBARS OR   ERHE SX         X4 44 E 
 LIKE AMBIGUITY FUNCTION &IGURE   ! SYMMETRICAL WAVEFORM TYPICALLY HAS A FREQUENCY THAT INCREASES OR DECREASES  WITH TIME DURING THE FIRST HALF OF THE PULSE AND DECREASES OR INCREASES  DURING  THE LAST HALF OF THE  PULSE ! NONSYMMETRICAL  WAVEFORM IS OBTAINED BY USING ONE 
 It indicates that the rrns phase variation about the mean phase plane must be less than A114 for  a one dB loss of pain. For shallow reflectors, the two-way path of propagation means that the  sirrfacc error nlirst be one-lialf this arnount, or 1/28.  Errors do more than reduce the peak gain of an antenna. 
 DIMENSIONALLY ACTIVE ELECTRONIC SCANNED ARRAYS %3!S  4HESE ARE POPULATED BY TRANSMITRECEIVE 42  MODULES  OFTEN INCORPORATING TWO POLARIZATIONS ( AND 6  %XAMPLES INCLUDE 2!$!23!4 
 Vivian, E. N. Leith, and G. 
 567–578, 1997. 50. R. 
 SBRs can encounter in space particle radia- tion that may be due to both natural phenomena and nuclear detonations. The satellite must be designed to operate for a reasonable lifetime in the natural space environment. This environment is a function of orbital altitude. 
 It is possible to  mechanically slew a nodding-beam height finder a full 180" in a relatively short time (within  two seconds, for example). With an operator making a height measurement manually, from  2 to 4 measurements per minute might be made. In one nodding-beam height finder, up to 22  target-heights per minute can be obtained when the slewing is controlled automatically for  maximum data rate by the computer of the associated data-handling system.29 The absolute  height accuracy of a nodding-beam height finder can be + 1500 ft (460 m) at 150 nmi (280 km)  range. 
    
 Timing accuracies on the order of a fraction of the transmitter's (compressed) pulse width are typically desired over the duration of an operation. Time synchronization can be accomplished directly by receiving a signal from the transmitter, demodulating the signal if necessary, and using the demodulated signal to . synchronize a clock in the receiver. 
 FICATION OF WIND DIRECTION )T MAY  THEREFORE  BE ASSUMED THAT THESE DATA REPRESENT SOME KIND OF AVERAGE OF UPWIND  DOWNWIND  AND CROSSWIND DIRECTIONS !S WILL BE SEEN  THIS AVERAGE IS ABOUT  TO  D" SMALLER THAN THE UPWIND RETURNS -OREOVER  THE EARLY .2, &2 DATA WAS USED LIBERALLY IN THE OLDER DATA SUMMARIES  AND IT WAS NOTED  ABOVE THAT THERE IS A DIFFERENCE OF  TO  D" BETWEEN THE EARLY AND LATER PRESENTATIONS OF THE SAME .2, &2 DATA  THE  LATTER BEING USED IN &IGURE A  AND B 7ITH THESE  CORRECTIONS  THE CURVES MIGHT SHOW CLOSER AGREEMENT .EVERTHELESS  IT IS CLEAR THAT UNCRITICAL USE OF PUBLISHED CLUTTER DATA COULD LEAD RADAR SYSTEMS DESIGNERS TO CHOOSE SEA CLUTTER ESTIMATES MANY D" APART FOR THE SAME CONDITIONS 4HE .2, &2 DATA SET IS UNIQUE IN THAT NO OTHER PROGRAM HAS REPORTED MEASURE 
 CONSTANT COMPONENTS -ICROWAVE  RADARS MIGHT BE FROM ABOUT  -(Z TO ABOUT  '(Z  BUT THESE LIMITS ARE NOT RIGID . £°Ó  2!$!2 (!.$"//+  AIRPORT 
 Gaseous or diode receiver-protectors are designed to be nonlinear during the transmitted pulse and reflect the incident energy back toward the antenna. Isolators or circulators are often employed to absorb most of the reflected fun- damental, but they are generally much less effective at the harmonics. Moreover, these ferrite devices are nonlinear in themselves and can generate harmonics. 
 Expendable decoys are ejected (or  dropped) from the aircraft whereas towed decoys are tethered behind the aircraft.  Expendable decoys contain miniature jamming systems that are small enough to fit into  a standard chaff/flare dispenser. The decoy orients itself to the air stream by deploying  low-drag aerodynamic fins sufficient to maintain stable flight. 
 49SCR-270-D-RADAR  • Detected Japanese aircraft approaching Pearl Harbor • Performance characteristics: SCR-270-D Radio Set Perfor mance Characteristics (Source: SCR-270-D Radio Set Te chnical Manual, 1942 ) Maximum Detection Range . 250 miles Maximum Detection altitude . 50,000 ft Range Accuracy   . 
 75 CHO 998-5  EASCON. pp. 107-A 10 107-Ci, 1975. 
 WAVE %)+ WHEN OPERATING AT A CENTER FREQUENCY OF  '(Z WITH A  '(Z BANDWIDTH  HAS A PEAK POWER OF  K7  AVERAGE POWER OF  7  ABOUT  DUTY CYCLE  GAIN OF  D"  PULSE WIDTH OF  §S  AND IS LIQUID COOLED )T HAS MUCH LOWER POWER THAN A GYROKLYSTRON DISCUSSED LATER  AT THIS FREQUENCY  BUT ITS  CM BY  CM DIAMETER  SIZE IS CONSIDERABLY SMALLER AND IT COSTS CONSIDERABLY LESS THAN A GYROKLYSTRON ! SIMILAR %)+  ALSO BUILT BY #0)  HAS BEEN USED IN THE .!3! #LOUD3AT SPACEBORNE  RADAR THAT PROVIDES THE VERTICAL PROFILE OF CLOUDS FOR UNDERSTANDING CLOUD EFFECTS ON BOTH THE WEATHER AND CLIMATE  )T OPERATES AT A CENTER FREQUENCY OF  '(Z WITH A   -(Z BANDWIDTH   K7 PEAK POWER   §S PULSE DURATION   (Z PRF  AND AN EFFICIENCY OF  )T IS CONDUCTION COOLED %ACH CAVITY IS A SHORT PIECE OF RESONANT SLOW 
 Another problem is to know when graceful degradation has  gone too far and maintenance is needed.  The full testing of an array radar system is often more complicated than with conven­ tional radar systems. Also, the incorporation of IFF can be more complicated than with  rotating antennas. 
 Geosci. Remote Sens. 2006 ,44, 2972–2982. 
 Price, S. Darlington, and W. J. 
 The RCS pattern of a Rayleigh scatterer is very broad, especially if  the object has similar transverse and longitudinal dimensions. The magnitude of the  echo is proportional to the square of the volume of the object and varies as the fourth FIGURE 14.16  Azimuth-plane MOM-predicted edge-on  RCS of a flat plate having the planform shown in Figure 14.15  for wing leading edges 5 l in length. The incident electric field  was in the plane of the plate. 
 Although it may be  employed to cover a limited sector-as does the raster scan-nodding scan may also be used  to obtain hemispherical coverage, that is, elevation angle extending to 90° and the azimuth  scan angle to 360°.  The helical scan and the nodding scan can both be used to obtain hemispheric coverage  with a pencil beam. The nodding scan is also used with height-finding radars. 
 .i  Boxcar generator. When extracting the modulation imposed on a repetitive train of narrow  pulses, it is usually convenient to stretch the pulses before low-pass filtering. This is callet!  boxcaring, or satnple and hold. 
 4.1  4.1 Introducti on  .............................................................  4.1  The Transmitter as Part of a Pulsed Radar  System  ............................................................  4.1  Why So Much Power?  ....................................... 
 43-47,  November, 1965. RADAR ANTENNAS 277  113. Scruton, C., and P. 
 lcirrd, where the clutter echoes might be as much as 50 to 60 dB  greater than aircraft eclioes. MTI or pulse-doppler radar is commonly used for tliis  application to remove the background clutter.  The detc7ctiorr of'srirfacc targets over land, where moving vehicles or personnel can be separated  from clutter by means of MTI. 
 Aperture blocking  degrades the performance of an antenna by lowering the gain, raising the sidelobes, and filling  in the nulls. The effect of aperture blocking can be approximated by subtracting the antenna  pattern produced by the obstacle from the antenna pattern of the undisturbed aperture. This  procedure is possible because of the linearity of the Fourier-transform that relates the aperture  illumination and the radiated patternt An example9 of the effect of aperture blocking caused by  the feed in a paraboloid-reflector antenna is shown in Fig. 
 SHIP DATA $EPENDING ON THE USER 
 Trunk and George12 were among the first to note that something other than the convi:n­ tional receiver design should be used when the clutter pdf is not Rayleigh. They showed that  the median detector gave better performance in non-Rayleigh clutter than the conventional  receiver (which can be called a mean detector). In this detector, the median v,lue of the 11  received pulses is found and compared against a threshold. 
  
 STATE BOTTLE v WHEREIN A MECHANICALLY ROTATING ANTENNA IS FED FROM A SINGLE PORT  AND THE POWER AT THE PORT IS THE SUMMATION OF THE OUTPUTS OF MANY AMPLIFIER MODULES 4HOSE MODULES MIGHT BE PHYSICALLY LOCATED  FOR EXAMPLE  BELOW DECK ON A SHIP AWAY FROM THE ANTENNA 3OLID 
 CERNED 4HE TIME SEPARATION OF THE TARGETS IS RELATED TO THEIR PHYSICAL SPACING AS WELL AS THE VELOCITY OF PROPAGATION  WHICH CAN VARY DEPENDING ON THE MATERIAL PROPERTIES 7HERE THE TARGETS ARE WELL SEPARATED IN RANGE  IT IS RELATIVELY STRAIGHTFORWARD TO  SEPARATE THE RADAR REFLECTIONS  BUT THIS BECOMES PROGRESSIVELY MORE DIFFICULT AS TARGETS BECOME CLOSER TOGETHER  AS INSTEAD OF SEPARABLE TIME 
 Ia uses filters which are conjugates of each other for the expansion and compression filters. A filter is also matched to a signal if the signal is the complex conjugate of the time inverse of the filter's response to a unit impulse. This is achieved by apply- ing the time inverse of the received signal to the compression filter, as shown in Fig. 
 The portion of the signal energy  contained in the early gate is less than that in the late gate. If the outputs of the two gates arc  subtracted, an error signal (Fig. 5.17c) will result which may be used to reposition the center of  the gates. 
 DELAY COMPONENTS.   3/,)$ 
 LENGTH  OR OBSERVATION TIME )T IS COMMON PARLANCE TO REFER TO IMAGERY AS MAPPINGS OF THE NORMALIZED BACKSCAT 
  4HIS COR 
 4.The received signal must see areasonably good match into the receiver, and thelosses must bekept toaminimum. Some refinements intherudimentary system ofFig. 11.14 areneces- sary tomeet the above requirements. 
 Figure 7.27a illustrates the  antenna elevation pattern for an air-search radar which is desired to compensate for STC and  yet provide a signal independent of range, as does the cosecant-squared pattern.97 Figure 7.27b  shows the coverage or a long-range radar with such an antenna pattern.  Beam shaping may also be employed to increase the target-to-clutter ratio in some cases.  A target at high elevation angles competes with surface clutter at low angles. 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing.  RADAR DIGITAL SIGNAL PROCESSING  25.376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 In order to use an FPGA most efficiently, we have to take advantage of all of  the resources it offers. These include not only the large numbers of logic elements,  multipliers, and memory blocks, but also the rate at which the components can be  clocked. 
   PP n     , " 7ETZEL  h! MINIMALIST APPROACH TO SEA BACKSCATTERTHE WEDGE MODEL v IN  523) /PEN  3YMP 7AVE 0ROPAGAT 2EMOTE 3ENSING AND #OMMUNICATION  5NIVERSITY OF .EW (AMPSHIRE   $URHAM  PREPRINT VOLUME  *ULY n!UGUST     PP n   3 / 2ICE  h2EFLECTION OF ELECTROMAGNETIC WAVES FROM SLIGHTLY ROUGH SURFACES v  #OMMUN    0URE !PPL -ATH  VOL   PP n     7 ( 0EAKE  h4HEORY OF RADAR RETURN FROM TERRAIN v IN  )2% .AT #ONV 2EC   VOL       PP n   ' 2 6ALENZUELA  h$EPOLARIZATION OF %- WAVES BY SLIGHTLY ROUGH SURFACES v  )%%% 4RANS    VOL !0 
 DELAY COHERENT CANCELER  RF IS THE RMS FREQUENCY SPREAD OF  THE GAUSSIAN CLUTTER POWER SPECTRUM  IN HERTZ AND  FR IS THE RADAR REPETITION FREQUENCY   IN HERTZ 7HEN THE VALUES OF  RF FOR SCANNING MODULATION IN %Q  ARE SUBSTITUTED IN  THE ABOVE EQUATIONS FOR )  THE LIMITATION ON ) DUE TO SCANNING IS   )N  y      )N  y      )N  y   . 
 RANGE CONTOURS ARE CONCENTRIC CIRCLES WITH THE SUBRADAR POINT AT THE CENTER hNADIR LINEv REFERS TO THE LOCUS OF  SUBRADAR POINTS  C  #ONSTANT 
 K.: FFT Doppler Filter Performance Computations, NRL Memorandum Report 2744, Naval  Rrsc~arclr Laboratory, Wasliington, D.C., March, 1974.  40. Jensen, A. 
 For analyzing the velocity, the Doppler Frequency will be enumerated or filtered out b y a fi l- terbank.  A typical Doppler signal is shown in Figure 7.3.    fAfo fo+fD fo-fD   Figure 7.3  Typical Doppler signal of CW Radar. 
 E. N.: Radar Systems with Electronic Sector Scanning, J. Brir. 
 corresponds to a cross-range. or along-track, resolution of o/Ah, or  which is wliat was obtaincd in Eq. (14.6) from the synthetic aperture model. 
 All of the spacecraft in the series (five radars and  six optical systems) use sun-synchronous orbits at ∼500 km altitude. The radar’s  mass is ∼200 kg. SAR-Lupe. 
 This fact ischiefly duetoadifference inemphasison some of the functions. For example, itwould befoolish todesign abroadcast receiver with theultimate insensitivity when theweakest signal that can bedetected isdetermined largely byman-made and natural static. In theradar portion ofthespectrum, ontheother hand, external sources of interference are normally negligible, and consequently the sensitivity that can beachieved inaradar receiver isnormally determined bythe noise produced inthereceiver itself. 
 - 4HIS SECTION SHOWS THE APPLICATION OF THE PREVIOUSLY DESCRIBED %##- TECHNIQUES TO SURVEILLANCE  TRACKING  PHASED 
 SOURCE SIGNAL "ECAUSE MOST TARGETS  SUCH AS AIRCRAFT  ARE COMPLEX IN SHAPE  THE TOTAL ECHO SIGNAL IS COMPOSED OF THE VECTOR SUM  OF A GROUP OF SUPERIMPOSED ECHO SIGNALS FROM THE INDIVIDUAL PARTS OF THE TARGET  SUCH AS THE ENGINES  PROPELLERS  FUSELAGE  AND WING EDGES 4HE MOTIONS OF A TARGET WITH RESPECT TO THE RADAR CAUSES THE TOTAL ECHO SIGNAL TO CHANGE WITH TIME  RESULTING IN RANDOM FLUCTUATIONS IN THE RADAR MEASUREMENTS OF THE PARAMETERS OF THE TARGET 4HESE FLUCTUA 
 297–301, April 1965. ch25.indd   39 12/20/07   1:40:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 It should therefore  be used with caution as an ECCM device. If incorporated in a radar, provision should be  included for switching it out of the receiver when it does more harm than good.,  A c*otlsturrt ,/idsc~-alarm riltr (CFAR) receiver is used with automatic detection systems to  keep the false-alarm rate constant as the noise level at the receiver varies (Sec. 10.7). 
 de Loor, P. Hoogeboom, and E. P. 
 FUL EXPRESSIONS FOR THE MEAN SQUARE ERROR OF MEAN POWER AND MEAN VELOCITY ESTIMATES 0OWER %STIMATION  )T IS WELL KNOWN  THAT FOR A GAUSSIAN RANDOM PROCESS USING  SQUARE 
 84. W. J. 
 Gardner, “Doppler spectra of S band and X band signals,” IEEE Trans. Suppl .,  vol. AES-3, pp. 
 Xing, X.M.; Wen, D.; Chang, H.C.; Chen, L.F.; Yuan, Z.H. Highway deformation monitoring based on anintegrated CRInSAR algorithm—Simulation and real data validation. Int. 
 If the direct signal from the transmitter is available at the receiving site, it can be used as a  reference signal to extract the doppler frequency shift. However, the direct signal can seriously  interfere with the measurement of the angle of arrival, just as does a multipath signal. To  extract the angular location of the target, the direct signal must be separated in some manner  from the target signals. 
 The range-tracking error may be sensed in many ways. The most commonly used  method is the early- and late-gate technique (see Figure 9.16). These gates are timed  so that the early gate opens at the beginning of the main range gate and closes at the  center of the main gate. 
 '34~^° The adaptive array is a generalization of the SLC system concept described in the preceding subsection. The basic theory of jammer cancellation and target enhancement is considered first, and attention is then focused on the use of adaptive arrays to obtain superresolution capabilities which can be of help for ECCM. The implementation of the adaptive array concept is more and more related to digital beamforming technology.41"43 Jammer Cancellation and Target Signal Enhancement. 
 58. T. T. 
 A. Ross: Radar Cross Section of Targets, chap. 27 of the " Radar Handbook," M. 
 Power from the transmit twismixed ~vith thec-w echo from the target. After detection., the beats between the two frequencies fand f’can be 626. SEC. 
   30!#% 
 An airborne radar obtains a series of images of a ship that is expe - riencing pitch/roll/yaw in the waves, and the user is able to identify the ship type and  characteristics. Musman et al. discuss feature extraction, multiframe processing, and  a capability for automatic target recognition (ATR) of ships. 
 Thus the transmitting and receiving antennas must be within line of sight of each other or  nearly so. (The forward-scatter beamwidth from a sphere of radius a is approximately 2)./na,  when a/A~ t.60)  Another consequence of a bistatic radar designed to take advantage of the large forward­ scatter cross section is the loss of doppler and target-position information. When p = 180°, the  doppler frequency is zero; therefore moving targets cannot be discriminated on the basis of  +20  CD  "O  10 -ka 20  20L-..J._______L__L__J~..J..-.....,__,___,_~,__~~~~~~~~~~  0 20 40 60 80 100 120 140 160 180  Scattering angle /1, deg ; '  Figure 14.13 Bistatic cross section ab of a sphere as a function of the scattering angleµ and two values of  ka = 2r<.a/A, where a is the sphere radius and l is the wavelength. 
 Sensors 2019 ,19, 1920 Suppose that the aircraft ﬂies along to the X-axis with velocity v, and with the ﬂight altitude, H, and the initial slant range between the target, R0. The azimuth angle and the elevation angle are θand φ, respectively. It is assumed that a linear frequency-modulated (LFM) signal is transmitted, and it can be written as: s(τ)=rect⎭parenleftBigg τ Tp⎭parenrightBigg exp⎭bracketleftbigg j2π⎭parenleftbigg fcτ+γ 2τ2⎭parenrightbigg⎭bracketrightbigg (1) whereτdenotes the fast time, Tpdenotes the pulse width, fcis the carrier frequency of the transmitted signal, and rect(·) stands for the unit rectangular function. 
 VI performance 4-25 4.7.1 ASV Mk. VIA performance 4-28 4.8 Improvements to ASV Mk. VI 4-30 References 4-32 5 ASV Mk VII 5-1 5.1 Development of ASV Mk. 
 Thedelaytimecanbevarioo bychanging eitherthenumberofstages(acapacitive storageelement anditsassociated switch)orbychanging theswitching frequency controlled byadigitalclock.CCDsprovidea similarfunction exceptthatchargepacketsaretransferred toadjacent potential wellsby clocked voltagegradients. Thesampling frequency mustbesuchastoobtainoneortwo samples perrangeresolution cell.Sincethetimingiscontrolled byadigitalclock,thedelay canbemadeverystable,justaswithdigitalprocessors. However, noAjDorDjAconverters arerequired asindigitalsystems.Ithasbeenclaimedthatsuchdevicesaremoreeconomical in cost,consume lesspower,areoflesssize,andofgreaterreliability thandigitalprocessing. 
  
 The chapter ends with an approach to the problem of evaluating the efficacy of ECCM and ECM techniques (Sec. 9.12). There is a lack of theory to properly . 
 POLARIZATION MAPPING  3CAN3!2  A VARIETY OF DUAL 
 The feed isfrequently the straight opening between two identical parallel conducting sheets which arejoined along their curved backs byaparabolic reflector strip. Just inside thecenter oftheopening, atthefocus oftheparabolic strip, islocated theopen end ofawaveguide which irradiates the parabola, thereby setting upthe propagation of energy between the two sheets and straight out through the opening. This assembly iscalled a‘‘pillbox.” Microwaves may bepropagated between the sheets with the electric field polarized either parallel or perpendicular tothesheets. 
 VAPOR 4HE DRY ATMOSPHERE COMPONENT IS WELL 
 P. Debye, Polar Molecules , New York: Chemical Catalog Co., 1929. 21. 
 The ability to steer the beam electronically can be used lo  stabilize the beam-direction when the radar is on a platform, such as a ship or aircraft,  that is subject to roll. pitch, or yaw.  The above attributes of an array antenna offer the radar systems engineer additional  flexibility in attempting to meet the requirements of radar applications. 
 The measured MTI improvement  factor of the M1.1) on as1 ASR radar was about 45 dB, which represented a 20 dB increase over  the ASR's conventional three-pulse MTI processor with a limiting IF amplifier. In addition,  the MTI) achieves a narrower t~otcli at zero velocity and at the blind speeds.  7'11e processor is preceded by a large dynamic range receiver to avoid the reduction in  improvement factor caused by limiting (Sec. 
 Geophys. Res ., vol. 88, pp. 
 ARRAY AROUND THE WORLD 0ROGRESS AND FUTURE TRENDS v  )%%% )NT 3YMP ON  0HASED 
 The  feed horns are H- or V-polarized, so that polarimetric diversity is also supported by this  arrangement. Mission design includes spacecraft steering to support squinted aspects  relative to the reference side-looking orthogonal viewing. The high-power stage is  comprised of ten channeled TWTAs,* eight of which are required in combination,  leaving two as redundant backup. 
 Often, a combination of sensitivity time  control (STC) and pulse to pulse phase coding is used to reject multiple time around  echoes (MTAE).8,16,62,63 The amount of presummation (PRESUM) and post detection  integration (PDI) as a function of beam position off the velocity vector is shown in the  lower right of Figure 5.33. For each different angle, there is a different doppler spread  across the beam. Therefore, in order to maintain a constant beam-sharpening ratio,  different amounts of presumming must be used for each beam position. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI.  AIRBORNE MTI  3.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 must also span the spatial directions of that interference. 
 408-413, D. Van Nostrand Company, Inc., Princeton, N.J., 1955.  56. 
 3!2 PROCESSING NEXT SECTION  FOR EACH  SUBPATCH SEE ALSO 3ECTION  OF !USHERMAN ET AL  4HE NEWER  2ANGE -IGRATION !LGORITHM 2-!  SEE #HAPTER  OF #ARRARA ET AL    ORIGINALLY DEVELOPED FOR SEISMIC APPLICATIONS  PROVIDES THE MOST THEORETICALLY CORRECT SOLUTION TO THE STRIPMAP IMAGE PROBLEM )T DOES NOT MAKE A FAR 
 TAINING THE JAMMER AND STILL MAINTAIN DETECTION CAPABILITIES WITH THE REMAINING BEAMS !LTHOUGH THEY ADD COMPLEXITY  COST  AND POSSIBLY WEIGHT TO THE ANTENNA  REDUCTION OF MAIN 
 1I;E'i'; ~'I.[I~Is., VOI. AP-13, j>p. 823 824. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.436x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 As remarked earlier, the maximum frequency that will reflect energy back to the  Earth during the day may be more than twice that at night; therefore, the occupancy  tends to be denser at night than during the day—a problem compounded by the lower  absorption and, hence, reception of more distant signals. Looked at over longer timescales, various patterns and trends emerge. 
 Separation of the two frequencies is sufficient to make their Swerling 1 fluctua - tions independent. This depends on the physical length of the target in the range  dimension lR. The minimum frequency separation is 150 MHz/ lR (m); 25 MHz  will maintain the diplex benefit for aircraft longer than 6 m (20 ft). 
 Conversely, ASV Mk. VI showed a spread between 37 nmi and 39.75 nmi, representing a variation of only 1.25 dB. Thedetection ranges from each trial were corrected to the mean radar sensitivity over the trial period and the resulting average comparisons between ASV Mk. 
 Withthisassumption, bothscatterers areilluminated simultaneously by thepulsepacket.Another restriction placedonIisthatitbesmallcompared withthedistance Rfromradartotarget.Furthermore, R1~R2~R.Thecrosssections ofthetwotargetsare assumed equalandaredesignated 0'0.Thecomposite crosssection O'rofthetwoscatterers is O'r [(47[1.l)]0'0=2 1+cos-y'SIn(, (2.37) TheratioO'r/O'Ocanbeanything fromaminimum ofzerotoamaximum offourtimesthecros~ sectionofanindividual scatterer. PolarplotsofO'rlO'oforvariousvalucsofII)",areshownin Fig.2.15.Although thisisarathersimpleexample ofa..complex" target,itiscomplicated enoughtoindicate thetypeofbehavior tobeexpected withpractical radartargets. Theradarcrosssections ofactualtargetsare~armorecomplicated instructure thanthe simpletwo-scatterer target.Practical targetsarecomposed ofmanyindividual scallerers. 
 Bronski, J. W. Crispin, A. 
 Compensation might also be necessary ror '' range walk•· which is the result  of the target·· walking" through one or more range-resolution cells during the time or observa­ tion. The achievable cross-range. or along-track, resolution worsens as the squint angle in­ creases from broadside (,5cr ~ 1/sin 0, where O = angle between aircraft heading and squinted  antenna beam direction). 
 1956.  48. Ulahy. 
 COMPARISON MONOPULSE RECEIVER 4HE SYSTEM SHOWN IN &IGURE  WOULD PROVIDE A RELATIVELY GOOD DIFFERENCE 
 Lataitis, B. L. Weber, D. 
 Howard: The Effects of Automatic Gain Control Performance on the Tracking  Accuracy of Monopulse Radar Systems, Proc. IRE, vol. 47, pp. 
 The width of the filter will depend upon the time  on target, equipment fluctuations, and other effects which broaden the echo-signal spectrum as  discussed previously. Each of the doppler filters can have its own individually set threshold  whose level is determined by the amount of noise or clutter within the filter. This can be done  146INTRODUCTION TORADAR SYSTEMS Altitudereturn__~Transmitter toreceiver leakage /'Main-lobe cluttery -,-~Target echo(head-on) fo+fctfo+fd fo+2v/AReceiver noise Frequency Figure4.36Portion ofthereceived signalspectrum inthevicinity oftheRFcarrierfrequencyh.forapub doppler AMTIradar.(AfterMaquire, 70Proc.Natl.ConfonAeronaut. 
 Consider only an area located 2/2 to 3Vz km from the radar (R « 35 dB, where the range R is in decibels relative to 1 m) and illuminated with an antenna having 0.1 rad of beamwidth. There is a reflecting cross section a of approximately *In this chapter a 1-Hz bandwidth has been chosen as the reference. There has been no consistent practice in the literature, since it has been customary to use either the bandwidth of the system in ques- tion or that of the measuring equipment.TRANSMITTERCOUPLERANTENNA SIDESTEP OSCILLATORSINGLE-SIDEBANDGENERATOR DOPPLER PROCESSOR BRIDGEMIXERAMPLIFIER MIXERANTENNA . 
 Waterman, A. T., Jr.: A Rapid Beam Swinging Experiment in Transhorizon Propagation, IRE  Trans., VQI. AP-6, pp. 
 A cursory examination of Eqs. 14.18 and 14.19  will show why. The denominators of both expressions contain the difference of two cosine terms  that become equal in two different cases. 
 The surface of the reflector is divided into rectangular grid regions of area dA (Fig. 6.24), which intercept the feed-radiated field. The surface current then is the cross product of the H field with the normal to the surface n modified by differ- ential area and a phase term, 7 = n x H(v] (v • n) e " ikr dAl4vr (6.24)FIG. 
 (2.2) is not the 3-dB, or half-power,  bandwidth commonly employed by electronic engineers. It is an integrated bandwidth and is  given by  where H( f) = frequency-response characteristic of IF amplifier (filter) and fo = frequency of  maximum response (usually occurs at midband).  When H( f) is normalized . 
 Data links such as JTIDS/Link 16 and Link 22 can share  apertures with GPS and L band satellite communications (L SATCOM). EW apertures  must be broadband by nature and can be shared with radar warning receivers (RWR),  radar auxiliaries, and some types of CNIs. FIGURE 5.4  MFAR RF apertures share low-level RF ( adapted 2 ). 
   DATA HAS LED TO MAPS OF .EW /RLEANS SUBSIDENCE RATES  WHICH VARY FROM  ^ MMY TO  MORE THAN  MMY  WITH A SENSITIVITY ON THE ORDER OF  MMY !NY APPROACH TO PHASE DIFFERENCE MEASUREMENT IS SUBJECT TO THE FUNDAMENTAL  O  AMBIGUITY CHARACTERISTIC OF PHASE ESTIMATION ALGORITHMS  )N MANY RADAR SITUATIONS   KNOWLEDGE OF THE PHYSICAL CONSTRAINTS OF THE SITUATION  COUPLED WITH PHASE UNWRAPPING ALGORITHMS  IS SUFFICIENT FOR THE PURPOSE 0OLARIMETRY  &OR ANY GIVEN POLARIZATION OF THE TRANSMITTED WAVE  THE REFLECTIVITY  PROCESS IN GENERAL WILL GIVE RISE TO A DIVERSITY OF POLARIZATIONS IN THE BACKSCATTERED WAVE 4O OBSERVE THESE  THE RADAR MUST BE DUAL 
 ALLY ALSO USED IN THE EXCITER TO UPCONVERT MODULATED WAVEFORMS TO 2& FOR OUTPUT TO THE TRANSMITTER )N MANY EARLY RADARS  THE ONLY FUNCTION OF THE LOCAL OSCILLATORS WAS CONVERSION OF  THE INPUT SIGNAL FREQUENCY TO THE CORRECT INTERMEDIATE FREQUENCY -ANY MODERN RADAR SYSTEMS  HOWEVER  COHERENTLY PROCESS A SERIES OF RETURNS FROM A TARGET 4HE LOCAL OSCIL 
 PLING FREQUENCY IS THE INVERSE OF THE SAMPLING INTERVAL AND IS TYPICALLY DESIGNATED  F S  3AMPLED SYSTEMS ARE SUBJECT TO THE .YQUIST LIMIT  WHICH LOWER BOUNDS THE SAMPLING  RATE AT WHICH RECONSTRUCTION OF THE UNSAMPLED SIGNAL FROM ITS SAMPLES IS POSSIBLE WITH 
 CROSSRANGEv PRINCIPLE 4HE TOP ILLUSTRATION IN &IGURE  ILLUSTRATES THE APPEARANCE OF A FLAT LANDSCAPE TO  THE HUMAN EYE OR A CAMERA  4HE TERRAIN IS ILLUMINATED BY SUNLIGHT  AT LEAST PARTIALLY DIFFUSED THROUGH THE ATMOSPHERE !T THE EYE  EACH PIXEL SUBTENDS THE SAME AZIMUTH AND ELEVATION ANGLES 4HUS  PIXELS FARTHER FROM THE EYE ARE LARGER COARSER RESOLUTION   IN BOTH DOWNRANGE AND CROSSRANGE  THAN PIXELS CLOSER TO THE EYE 4HE BOTTOM ILLUSTRATION IN &IGURE  SHOWS THAT  FOR A 3!2 IMAGE  THE SITUATION IS  QUITE DIFFERENT ASSUMING ADEQUATE 3.2  4HE RANGE PIXEL SIZE C R IS   DYRC "  COS    0IXELS  FARTHER FROM THE 3!2 ARE SMALLER IN RANGE SMALLER GRAZING ANGLE AND FINER  DOWNRANGE RESOLUTION  THAN PIXELS CLOSER TO THE 3!2 AND CROSSRANGE RESOLUTION IS INDEPENDENT OF RANGE 7HEN WE DISPLAY A 3!2 IMAGE  ESPECIALLY OF A LARGE LANDSCAPE  IT IS USUALLY MOST  SATISFYING TO DISPLAY IT WITH THE 3!2 DIRECTION AT THE TOP 4HE FINER RESOLUTION PIXELS ARE AT THE BOTTOM  JUST AS THEY ARE WITH A NATURALLY ORIENTED OPTICAL IMAGE 4HIS ORIENTATION TENDS TO LOOK MOST NATURAL TO A HUMAN OBSERVER "ECAUSE 3!2 IMAGERY AND OPTICAL IMAGERY ARE COLLECTED USING ENTIRELY DIFFERENT  PHYSICAL PRINCIPLES  WE SHOULD NOT BE SURPRISED IF THEY LOOK DIFFERENT  ! GOOD EXAMPLE  OF THIS IS PROVIDED IN A 3!2 IMAGE OF THE 7ASHINGTON -ONUMENT  COURTESY OF THE %NVIRONMENTAL 2ESEARCH )NSTITUTE OF -ICHIGAN  NOW 'ENERAL $YNAMICS  9PSILANTI  -) 4HE TOP ILLUSTRATION IN &IGURE  ILLUSTRATES THE COLLECTION  GEOMETRY AND THE SCHE 
 W .. (i Caryotakis. A. 
 46.Copeland, J.R.:RadarTargetClassification byPolarization Properties, Proc.IRE,vol.48,pp. 1290-1296, July,1960. 47.Knott,E.F.,andT.B.A.Senior:CrossPolarization Diagnostics, IEEETrans.,vol.AP-20,pp. 
 Noise is a fundamental limitation to radar performance and t1ie1-efore Ciili bc all  effective countermeasure. The ECCM designer nii~st minimize tlie amount of noise a jarnmcr  can introduce into the radar receiver. It is difficult, however, to keep the noise out when the  jammer is being illuminated by the main beam of the radar antenna. 
 The latency of a processor is defined as the amount of time required  to observe the effect of a change at a processor’s input on its output. Achieving latency  goals often requires assigning smaller pieces of the workload to individual processors,  leading to more processors and a more expensive system. Another challenge facing  ch25.indd   35 12/20/07   1:40:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 OGY FOR VARIOUS SPACE 
 The receiver was rapidly switched toeach ofthefour receiving antennas inturn, and thedisplay correspond- ingyswitched totheproper deflection plate oftheappropriate indicator tube. Range could beread either ontheazimuth tube orontheeleva- tion tube. The arrangement ofthe receiving antenna patterns and of theindications isshown inFig. 
 SQUARED ELEVATION PATTERN AND A  AZIMUTH BEAMWIDTH )T IS REMOTELY CONTROLLED TO GIVE HORIZONTAL OR CIRCULAR POLARIZATION 4HE VERTICAL PATTERN SHAPING INTERACTS WITH THE 34# OF THE RADAR RECEIVER  AND IT IS  THEREFORE  NECESSARY TO TAKE THIS INTO ACCOUNT IN THE SYSTEM DESIGN 4O IMPROVE DETECTION  FREQUENCY DIVERSITY IS OFTEN USED ON PRIME SYSTEMS )!,! HAS ISSUED DETAILED RECOMMENDATIONS  ON THE OPERATIONAL AND TECHNICAL PER 
 LIMITED DETECTION THERE MAY BE A PENALTY FOR COVERAGE RATE 3OME RADARS USE HORIZONTAL TWO 
 Power amplifier modules that are not protected from high-load VSWR can be damaged by reflected power from the combiner. In addition, frequency-dependent phase and amplitude ripple may result from this configuration. Typical RF transmission media that are used in the construction of high-power combiners include coaxial transmission lines, microstrip or stripline transmission lines, or waveguide. 
 10.5] MAGNETRON CHARACTERISTICS 341 naltothetube and areaccessible tochange. Inmicrowave magnetrons, thecircuit elements areanintegral part ofthetube and must beincor- porated with great care into every new design. Thus any radar system designed tomeet anew setofconditions orto operate onanew frequency will require the development ofanew mag- netron type, oratleast acritical evaluation ofthe characteristics of existing types. 
 CALLED  DEPRESSED COLLECTOR    7ITH A SINGLE COLLECTOR  A SIGNIFICANT  FRACTION OF THE POWER INPUT TO THE TUBE IS DISSIPATED AS HEAT IN THE COLLECTOR )F THE VOLT 
 HARMONIC WHEN CAUSED BY WAVE MOTION )N PRACTICE  THE SHIP IS NAVIGATED ON NOTIONS BASED ON COURSE  HEADING  AND SPEED IN %ARTH AND SEA 
 TORS  HAVE BEEN EXPLOITED TO ACHIEVE IMPROVED PHASE NOISE PERFORMANCE 3!7 OSCIL 
  D" LEVEL HOWEVER  THESE ARE GENERALLY  MECHANICALLY SCANNED  AND THE LOW ERROR BUDGETS ARE ACHIEVED BY USING ALL 
 This further complicates the radar. (Pulse compression does not rdieve  the minimum-range problem of long pulses.)  Although the solid-state transmitter does not require high voltage, it does require large  current, perhaps several thousands of amperes in some applications. Wide bandwidth is one of  the more favorable properties of such devices; but the overall transmitter efficiency, especially  at the higher microwave frequencies, is not always as great as might be desired. 
 The narrower beam widths afford better deﬁnitionofthetargetand,thus,moreaccurateidentiﬁcationofthecenterofthetarget.Several targets close together may return echoes which produce pips on thePPI which merge, thus preventing accurate determination of the bearing of asingle target within the group. The effective beam width can be reduced through lowering the receiver gain setting. In reducing the sensitivity of the receiver, the maximumdetection range is reduced, but the narrower effective beam width providesbetter bearing accuracy. 
 Since the aspect entropy of pixels can discriminate isotropic and anisotropic scattering, the method prescreens the target from the isotropic clutters. Next, the method extracts aspect entropy at the target level. The aspect entropy of targets can discriminate between different types of targets. 
 SCOPE APPEARANCE AND STATISTICAL DESCRIPTION OF THE CLUTTER IN THIS REGIME OF LOW GRAZING ANGLES  3OME ATTEMPTS TO DESCRIBE THE PHYSICAL ORIGIN OF THESE PHENOMENA  WILL BE DISCUSSED IN 3ECTION  BELOW !T 6ERY ,OW 'RAZING !NGLES  4HERE IS SOME EVIDENCE THAT SEA CLUTTER MIGHT  DROP OFF MORE SHARPLY BELOW A  CRITICAL ANGLE IN THE NEIGHBORHOOD OF A DEGREE OR SO  4HIS CRITICAL ANGLE  OR  CRITICAL RANGE FOR A RADAR AT A FIXED HEIGHT  HAS BEEN OBSERVED  FROM TIME TO TIME SINCE FIRST NOTED IN EARLY OBSERVATIONS OF SEA CLUTTER 4HE CRITICAL  ANGLE HAS BEEN ASCRIBED TO INTERFERENCE BETWEEN DIRECT AND PERFECTLY  REFLECTED RAYS AT THE SCATTERING  TARGETS RESPONSIBLE FOR THE CLUTTER SIGNAL  ALTHOUGH THESE TARGETS REMAIN  UNSPECIFIED  !LTHOUGH THIS SIMPLE PICTURE COULD PRODUCE THE  2n DECAY THAT IS SOME 
 The circumference of the chart corresponds to infinite VSWR, or unity reflection  coefficient. Thus the region of low standing-wave ratio is toward the center of the chart.  196INTRODUCTION TORADAR SYSTEMS (4)loadsusceptance. 
 CESSES LEADS TO A NATURAL DIVISION OF THE IONOSPHERE INTO A NUMBER OF REGIONS $ 2EGION 4HIS REGION OCCUPIES THE LOWEST ALTITUDES CONSIDERED )T EXTENDS FROM   TO  KM  WITH ELECTRON DENSITY INCREASING RAPIDLY WITH ALTITUDE IN THE DAYTIME  )TS PROPERTIES REFLECT THE BALANCE BETWEEN FREE ELECTRON PRODUCTION BY THE INCIDENT  SOLAR RADIATION FLUX AND FREE ELECTRON LOSS VIA VARIOUS ELECTRON 
 For wide instantaneous bandwidth (rather than tunable bandwidth), time delays have to be added to prevent the beam from being scanned as the frequency is changed. The impedance of the radiating element at the aperture (with closely spaced elements) is approximately independent of frequency, but the element must be matched over the wide band. This is difficult to achieve without exciting harmful surface waves when scanning. 
 666–672. 56. G. 
 DIMENSIONAL VECTOR   SF !3    WHERE !3 IS THE SIGNAL AMPLITUDE AND THE ELEMENTS OF THE VECTOR  F ARE FI   EXP ;JOFSTI=  /N THE BASIS OF THIS DESCRIPTION OF SIGNAL AND CLUTTER  IT HAS BEEN SHOWN THAT THE OPTI 
    &)'52%  2EFLECTOR LEAKAGE LOSS VS TRANSMISSION LOSS. 
 IEEE Trans, vol. AP-23. pp. 
 Aperture-Field Method of Analysis.  The aperture-field reflector analysis  method is based upon ray-tracing principles and works well for symmetric, center-fed  parabolic reflectors. With this method, the aperture field distribution is calculated in an  x-y plane at z > 0 (Figure 12.1) by assuming coherent reflection of spherical radiation  from a feed at the focal point. 
 (From Von ~ulock'~, Co~irtesy Proc. IRE.)  (8.13)284INTRODUCTION TORADAR SYSTEMS Thehalf-power beamwidth is O-0-0"-~.~86A-B-+ - "-Nt/cosDo Therefore, whenthebeamispositioned anangleDootTbroadside, thebeamwidth intheplane ofscanincreases as(cosOorI.Thechangeinbeamwidth withangle00asderivedaboveisnot validwhentheantenna beamistoofarremoved frombroadside. Itcertainly doesnotapply whentheenergyisradiated intheendfiredirection. 
 Onecommon construction ofaTRconsistsofasectionofwaveguide containing oneormoreresonant filters. 362 INTRODUCTION TO RADAR SYSTEMS  ATR tubes  (fired)  Hece~ver  Tronsm~tter - - ,-- protector  Dumrny load Antenno  Short -slot S hort-slot  hybrid hybrid  ATR tubes  Tronsmitter Receiver  protect01  Dummy load Antenna  Short-slot S hort-slot  hybrid hybrid  Figure 9.7 Balanced duplexer using ATR tubes. (a) Transmit condition; (b) receive condition  and two glass-to-metal windows to seal in the gas at low pressure. 
 237–243 and reprinted in D. K. Barton, CW and Doppler Radars,   Section V-I, V ol. 
 H. Knittel (eds.), Norwood, MA: Artech House, 1972,  pp. 261–271. 
 79. Kros7c7ynsky. J.: EJfficiency of thc Two-Frequency MTI System. 
 0. As: System Properties of Jumping Frequency Radar, Philips Telecom. Rev.,  vol. 
 All airplanes detected on this arc will beindicated asdead ahead, since the train axis isori- ented tothis position. This indi- cation isofcourse false, and the two-axis mount therefore imper- fect inprinciple. The computer described below provides correction fordistortion ofthis type. 
 This isdone partly toensure increased range and partly toallow for the considerable unavoidable variations between the receivers of different beacons asinstalled and operated. 8.6. Frequency Considerations. 
 A  receiver protector, to be described later, is usually inserted between the duplexer and the  receiver for added protection.  Another form of balanced duplexer39 uses four ATR tubes and two hybrid junctions  (Fig. 9.7). 
 (This is similar to  the description of surface reflections and its effect on the elevation coverage, as in Sec. 12.2.)  The direct and the surface-reflected signals combine at the radar toman angle measure-  ment that differs from the true measurement that would have been made with a single target in  the absence of surface reflections. The result is an error in the measurement of elevation. 
 Radar was originally developed to satisfy the needs of the military for surveil- lance and weapon control. Military applications have funded much of the devel- opment of its technology. However, radar has seen significant civil applications for the safe travel of aircraft, ships, and spacecraft; the remote sensing of the environment, especially the weather; and law enforcement and many other ap- plications. 
 PGAP-1, pp. 126-134, February,  1952.  57. 
 DENT SAMPLES %QUATIONS  n  ARE  APPLICABLE  IN  HIGH  SIGNAL 
 8. Anderson, D. B.: A Microwave Technique to Reduce Platform Motion and Scanning Noise in Airborne Moving Target Radar, IRE WESCON Conv. 
 Chapman, “Venus: surface electromagnetic properties,”   J. Geophys. Res. 
 Amer. Meteor. Soc. 
 Theadvantage ofusingtwoprf'stodetecttargetsinrainisillustrated byFig.4.28.The prf'sdifferbyabout20percent. Atypicalrainspectrum withanonzero average velocity is depicted onthebottomline.(Precipitation atSbandmighttypically haveaspectral widthof ahout25to30knotsccntercd anywhere from-60to+60knots,depending onthewind conditions andtheantenna pointing.42)Thcnarrowspectrum ofthemovingaircraft isatthe rightofthefigure.Because offoldover itisshownasoccupying filters6and7onprf-l,and filters7and8onprf-2.Withprf-2,theaircraft velocity isshowncompeting withtherain clutter;butwithprf-litappears inonefilter(No.6) without anyrainclutter). Thus,by usingIwoprf'swhicharealternated everytopulses(one-half beamwidth), aircrafttargetswill usuallyappcarinatleastoncfilterfrecfromrainexceptforasmallregion(approximately 30 knotswidc)whcnthetarget'sradialvelocity isexactlythatoftherain. 
 23,811–23,818, 1995. 19. R. 
 2, no. 11, pp. 33–37, 1978. 
 TURE RADAR IN THE MARITIME ENVIRONMENT v  )%% #OLLOQUIUM ON 3YNTHETIC !PERTURE 2ADAR    .OVEMBER     PP n   # * #ONDLEY  h3OME SYSTEM CONSIDERATIONS FOR ELECTRONIC COUNTERMEASURES TO SYNTHETIC APERTURE  RADAR v )%% #OLLOQUIUM ON %LECTRONIC 7ARFARE 3YSTEMS  *ANUARY     PP n  - 3OUMEKH  h3!2 
 DEFINITION 46 TRANSMITTER FOR AIR SURVEILLANCE IN THE CO 
 (23.10), (23.2), and (23.4) into Eq. (23.1) gives P, = &^$M2Iff = P2M£IL^Z 8\V = p/Z r2 This simple expression illustrates that the received power is a function only of 0' (a constant dependent upon radar system parameters), is proportional to the ra- dar reflectivity factor Z, and is inversely proportional to r. In actual fact, the antenna gain is not uniform over the beam width, and the assumption of a uniform gain can lead to errors in the calculation of Z. 
 TO 
 The APC was funded by the Beijing Institute of Technology Research Fund Program for Young Scholars. Conﬂicts of Interest: The authors declare no conﬂict of interest. References 1. 
  4HE !.403 
 Tllc 3-dl3 t~i~ndwicith is widely i~sed, since it is easy to measure. The meastire~nent  of rioisc t)aridwicftli. I~owcvcr, irivolves a coriiplete knowledge of tlie resporrse cliaractet.istic  N(/ ). 
 Proc.IRE.vot.48.pp. JIll315.March.1960. 16.Farnett. 
 Shaped patterns like the cosecant-squared pattern are also used in  airborne radars that map the surface of the earth. 89  Antenna design. The design of a cosecant-squared antenna pattern is an application of th'c  synthesis techniques discussed in the preceding section. 
 NOISE AMPLIFIERS  SATURATING POWER AMPLIFIERS  OR SWITCHES   RESISTORS  CAPACITORS  INDUCTORS  DIODES  TRANSMISSION LINES  INTERCONNECTS  AND PLATED GROUND VIAS 4RANSMIT2ECEIVE -ODULE #HARACTERISTICS  4HE IMPACT OF ANTENNA ARRAY ELEC 
 So with the prior support information and the ﬁnal debiasing step, LS-CS-Residual can reconstruct the aspect dependent scatterings of the targets more accurately than CS and debiased-CS. The time taken by the three algorithms is given in the Table 1. Debiased-CS takes more time because of the debias step compared with CS. 
       
 DEPENDENT ! TARGET WITH TYPICAL  VELOCITY AT LONG RANGE HAS LOW ANGLE RATES AND A LOW 3.2  AND A NARROWER SERVO PASSBAND WILL FOLLOW THE TARGET WITH REASONABLY SMALL TRACKING LAG WHILE MINIMIZING THE RESPONSE TO RECEIVER THERMAL NOISE !T CLOSE RANGE  THE SIGNAL IS STRONG  OVERRIDING RECEIVER NOISE  BUT TARGET ANGLE SCINTILLATION ERRORS PROPORTIONAL TO THE ANGULAR SPAN OF THE TARGET ARE LARGE ! WIDER SERVO BANDWIDTH IS NEEDED AT CLOSE RANGE TO KEEP TRACKING LAG WITHIN REASONABLE VALUES  BUT IT MUST NOT BE WIDER THAN NECESSARY OR THE TARGET ANGLE SCINTILLATION ERRORS  WHICH INCREASE INVERSELY PROPORTIONAL TO TARGET RANGE  MAY BECOME EXCESSIVE 4HE LOW 
 All together, something  in excess of 20 new SARs are being launched in the first decade of the 21st century,  from at least eight different countries. Highlights of several of these systems are  summarized in the following paragraphs. COSMO-SkyMed . 
 NECTED TO EACH ANTENNA ELEMENT 4HE ADAPTIVE WEIGHT SOLUTION IS DEVELOPED BASED ON AT LEAST  ¾ . ¾ - VECTOR SAMPLES  R  OF LENGTH  - ANTENNA ELEMENTS  BY  . PULSES  4HE  ADAPTIVE WEIGHT SOLUTION IS DEVELOPED AND APPLIED TO THE RECEIVED SIGNALS FROM THE SAME ANTENNA ELEMENTS AND PULSES OF DATA 4HE ADAPTIVE WEIGHTED RESPONSE IS TYPICALLY PRO 
 Radar System Engineering," MIT Radiation Laboratory Series, McGraw-Hill  Book Company, New York, 1947, sec. (6.11).  46. 
 Timmoneri, “Systolic schemes for Joint SLB, SLC and adaptive phased-array,”  Proc. of Int. Conf. 
 VELOCITY 
 The basic properties of chaff are effective scatter area, the  character and time of development of a chaff cloud, the spectra of the signals reflected  by the cloud, and the width of the band that conceals the target.3,9,21,22 From a radar  viewpoint, the properties of chaff are very similar to those of weather clutter, except  that its broadband in frequency can extend down to VHF. The mean doppler frequency  of the chaff spectrum is determined by the mean wind velocity, while the spectrum  spread is determined by wind turbulence and a shearing effect due to different wind  velocities as a function of altitude.3 Decoys, which are another type of passive ECM, are a class of physically small  radar targets whose radar cross sections (RCS) are generally enhanced by using reflec - tors or a Luneburg lens to simulate fighter or bomber aircraft. The objective of decoys  is to cause a dilution of the assets of the defensive system, thereby increasing the sur - vivability of the penetrating aircraft. 
 The blind-speed problem and the  loss resulting therefrom are discussed in more detail in Chap. 4.  In a radar with overlapping range gates, the gates may be wider than optimum for  practical reasons. 
   -4) 2!$!2  Ó°x 4HE PROBLEMS ARE EXACERBATED WHEN ANOMALOUS OR DUCTED PROPAGATION OCCURS  ANOMALOUS PROPAGATION  AS USED HEREIN  IS WHEN THE RADAR ENERGY FOLLOWS THE CURVATURE  OF THE %ARTH  THUS CAUSING DETECTION OF BOTH FIXED AND MOVING CLUTTER AT LONG RANGES  &IGURE  FROM 3HRADER  SHOWS 00) PHOTOGRAPHS TAKEN WITH AN !232 
 ERROR 
 Since the synthetic-aperture radar is coherent, the image produced will have speckle; i.e.,  there will be constructive and destructive interference which results in a "breakup" of dis-  tributed scatterers. To reduce the effect of speckle and make a more " filled-in" image, the  same scene can be viewed from different aspects or at different frequencies, or both, and the  several images superimposed. The multiple looks can be obtained as in the searchlight mode  by dwelling with a positionable antenna on the same area. 
 DIMENSIONAL WEDGE PROBLEM  BUT HE DISTINGUISHED BETWEEN hUNIFORMv AND hNONUNIFORMv INDUCED SUR FACE CURRENTS 4HE  UNIFORM CURRENTS WERE NONE OTHER THAN THE SURFACE CURRENTS OF PHYSICAL OPTICS  WHEREAS THE NONUNIFORM CURRENTS WERE TAKEN TO BE UNDEFINED FILAMENTARY CURRENTS ALONG THE EDGE ITSELF 5FIMTSEV NEVER ATTEMPTED  TO WORK OUT HIS FILAMENTARY  FRINGE CURRENTS  BUT  INSTEAD TRACED THEIR EFFECT DIRECTLY TO THE FAR SCATTERED FIELD 2ECOGNIZING THAT THE FAR 
 L.. and P. M. 
 Signals appear asvertical lines 3,+acwtain range along the trace centered shout the elevation angle tithe targe~. Calculation ofheight from range and elevation angle Lpcriormwi automatically bythe selector s\vitch and relay equipment lw’J int’Ii stations (Sec. 6.9). 
 (/2):/. 2!$!2   Óä°Î£  RV CV V         
 3, pp. 717–725, July 1993. ch05.indd   43 12/17/07   1:27:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 54, pp. 1964.- 1965, December, 1966.  40. 
 PARAMETER THRESHOLD SEE 4ABLE    AND FOR THAT REASON  A TWO 
 IEEE T rans. Geosci. Remote Sens. 
 The cathode must be rugged to withstand the lleating and  disintegration caused by the back-bombardment of electrons. Back-bombardment increases  the cathode temperature during operation and causes secondary electrons to be emitted. For  this reason the heater power may be reduced or even turned off once the oscillations have  started. 
 TEM IS FUNCTIONING OR IS CAPABLE OF FUNCTIONING SHOULD BE AVAILABLE )N ONE POSSIBLE METHOD  THE PHASE SHIFTERS ARE PROGRAMMED TO FOCUS ON A NEARBY MONITOR PROBE AND SCAN PAST IT  4HIS WILL YIELD A CLOSE APPROXIMATION OF THE COMPLETE RADIATION PATTERN   WHERE GAIN AND SIDELOBES CAN BE MEASURED AND COMPARED WITH PREVIOUS RESULTS 4HE COMBINATION OF INDIVIDUAL ELEMENTS AND THEIR PHASE SHIFTERS AND DRIVERS  CAN ALSO BE CHECKED WITH THIS CONFIGURATION 4HE PHASE AT EACH ELEMENT IS SEQUENTIALLY ROTATED AT SOME LOW FREQUENCY THE AMPLITUDE AND PHASE OF THIS MODULATION AS RECEIVED BY THE PROBE RELATE DIRECTLY TO BOTH THE RELATIVE AMPLITUDE EXCITATION OF THE ELEMENT AND ITS .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°x RELATIVE PHASE SETTING /THER METHODS HAVE BEEN PROPOSED WHERE MEASUREMENTS  ARE COMPARED WITH PREVIOUSLY RECORDED ONES $EPLOYMENT OF !PERTURES  7ITH PLANAR ARRAYS  SCANNING IS LIMITED BY THE LOSS IN  GAIN AND THE INCREASE IN BEAMWIDTH CORRESPONDING TO THE REDUCTION OF THE APERTURE TO  ITS PROJECTED AREA 0RACTICAL EXTREME VALUES OF SCANNING ARE THEREFORE IN THE REGION OF  TO n ! MINIMUM OF THREE PLANAR ARRAY APERTURES IS THEN NECESSARY FOR HEMISPHERICAL COVERAGE 4HE ANTENNAS MAY BE POSITIONED AS SHOWN IN &IGURE   PERMITTING A VIEW THAT IS UNIMPEDED BY THE CENTRAL SUPERSTRUCTURE 4HE APERTURES WOULD NORMALLY BE TILTED BACK FROM THE VERTICAL TO BALANCE THE SCAN ANGLES 2ADIATING %LEMENTS  4HE MOST COMMONLY USED RADIATORS FOR PHASED ARRAYS ARE  DIPOLES  SLOTS  OPEN 
 FIGURATIONS OF THE 2& FIELD THAT CAN EXIST BETWEEN THE CATHODE AND THE RESONANT CAVITIES .   4(% 2!$!2 42!.3-)44%2   £ä°£x 4HESE DIFFERENT 2& FIELD CONFIGURATIONS  ALONG WITH COUPLING AMONG THE CAVITY RESO 
 4 Rectifier power supply, ,...,,.... 6 *With atmdard scanner, Lightweight wanner reduces total weight to117 lb.. N+ (b) FIG. 
 MAGNETRON TRANSMITTERS FOR THIS PURPOSE $EMANDS FROM OTHER SERVICES FOR MORE BANDWIDTH  PARTICULARLY FROM MOBILE COM 
 cc  ¯¯     \FD F 
 WORK  SO ACCURACY ESTIMATES ARE A BYPRODUCT &URTHER  SITE 
 1284-1294. Novem­ ber. 1947. 
 ¤ ¦¥³ µ 
 The overall goal of the Earth Observing System (EOS) is to advance the scientific understanding of the entire earth system on the global scale through developing a deeper understanding of the components of that system, interac- tions among them, and how the system is changing.66 International space sta- tion elements include the following satellites in polar and equatorial orbits (1) a NASA EOS platform at 824 km, sun-synchronous, 1:30 P.M. equator- crossing time, ascending-node orbit; (2) a European Space Agency (ESA) plat- form at 824 km, sun-synchronous, 10:00 A.M. equator-crossing time, descend- ing-node orbit; and (3) the manned space station in a 335- to 460-km 28.5° inclined orbit. 
 TO 
 C., et al.: The Pioneer Venus Orbiter Radar, 7976 WESCON Sess. 4, Los Angeles, Sept. 14-17, 1976. 
 FPP EEJF T JF TVIB VIB    4HE NORMALIZED COMPLEX ECHO CORRESPONDING TO THE VIBRATING TARGET IS THEN THE  COMPLEX PRODUCT OF THE ECHO CORRESPONDING TO THE STATIONARY PIXEL AND THE ECHO COR 
 Ant. Prop., vol. AP-21, pp. 
  
 The sum signal uses only the center two horns to limit its E field in the E plane as desired for the ideal field shaping. The use of smaller top and bottom horns is a simpler method of concentrating the E field toward the center of the feed, where the full horn width is not needed. The feeds described thus far are for linear-polarization operation. 
 The early-gate capacitor charges to a voltage proportional to the area of the first half  of the target video pulse, and the late-gate capacitor charges negatively proportion - ally to the late half of the target video. When the gates are properly centered about a  symmetrical video pulse, the capacitors are equally charged. Summing their charge  voltages yields a zero output. 
 THE 
 Doviak, “Velocity spectra of vortices scanned with a pulse-doppler,” J. Appl.  Meteorolo. 
 Materials that match very  closely the coefficient of thermal expansion (CTE) of the semiconductor material must  be used in the design of the housing such that cracking of the semiconductor devices  does not occur during thermal cycling that happens during normal operation or during  temperature changes during assembly and test. Electrical Interconnection Considerations.  The interconnection of MMIC chips  within the T/R module must utilize controlled impedance transmission lines with low  insertion loss. 
 9.1. Particularly inthe case ofairborne radar, where alarge antenna cannot betolerated foraerodynamic reasons, itisimportant toproduce sharp radar beams with anantenna structure ofmodest size. This demands the use ofmicrowaves. 
 E., I. S. Reed, and P. 
 3. Mallinckrodt, A. J., and T. 
 As an example of the effects of high resolution on land clutter, measurements have been  reported with a horizontally polarized C-band radar having a 15-ns pulse width (3 m resolu­ tion) and a 1.5° beamwidth.43 A rural region in England consisting of woods, fields, buildings,  villages, small towns, and structures such as pylons, was examined at ranges from 7 to 11 km.  It was found that 65 percent of the clutter exceeded 0. t m 2, 18 percent exceeded l m 2, and less  than 1 percent exceeded 10 m2• The clutter with radar cross sections greater than lO m2 was  limited to 6 m in length and was found to be associated with man-made objects such as  electricity pylons and buildings. 
 Note theexaggeration ofthevertical scale. Acontour ofconstant field strength isacontour ofconstant power intensity aswell; moreover, the intensity ofthe signal received from a radar target ofgiven cross section, located anywhere along such acontour, isthesame.1 Thus, iftheproper contour ischosenit will represent, as nearly asany curve can, the boundary ofthe region inwhich agiven target can bedetected. The reader’s earlier introduction tosome ofthe statistical factors involved inradar should prepare him forthe warning that such coverage diagrams arenotto betaken tooliterally. 
 The hard limiter is set low enough to ensure that receiver noise  is limited. Thus the output is unaffected by the level of the noise. A signal, however, causes the  output of the matched filter to increase by a factor M, equal to the ratio of the bandwidth of  the broadband filter to the bandwidth of the narrow-band (matched) filter. 
 In  one experimental design of a conical-shape radome, periodic resonant slots were cut into the  metallic surface so that approximately 90 percent of the radome surface was metal. Within its  design band (8.8-9.0 GHz) the transmission properties were nearly ideal and accommodakd  scanning antennas transmitting arbitrary polarized signals. The reduced response outside the  design band reduces the effects of out-of-band interference and can reduce the nose-on radar  cross section of the aircraft at frequencies other than that for which the antenna is designed. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar.  PULSE COMPRESSION RADAR  8.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 doppler tolerance of the LFM codes. 
 Two submarines were used as targets, at a distance of about 7 miles north of Lough Foyle. Because of the proximity of land, only homing aerials were used. Thereliable maximum ranges against a fully-surfaced submarine were 14 miles at 1500 ft, 11 miles at 1000 ft, and 7 miles at 500 ft. 
 Whenproperly illuminated byapointsourceatthefOCllS,the paraboloid generates anearlysymmetrical pencil-beam antenna pattern.Itschiefapplication hasbeenfortracking-radar antennas. Anasymmetrical beamshapecanbeobtained byusingonlyapartoftheparaboloid. This typeofantenna, anexample ofwhichisshowninFig.7.25,iswidelyusedwhenfanbeamsare desired. 
 Normally itwouldbeexpected thatthedecorrelation timewouldbe linearlyproportional tothefrequency, sincethedoppler-frequency shiftisalsolinearlyrelated tothcfrequency. However. experimental measurements showthattheratioofthedecorrela­ tiontimcatLbandtothatatXbandislessthanwouldbeexpected ifthelinearrelation applied. 
  D" &OR THIS REASON  WHEN THE TRANSMITTER STARTS PULSING  A SET 
 SITE ,    2 -s !IR SURVEILLANCEs 2ANGE INSTRUMENTATIONs 3ATELLITE TRACKINGs )NTRUSION DETECTION s !IR SURVEILLANCEs 2ANGE INSTRUMENTATIONs )ONOSPHERIC MEASUREMENTs 7IND MEASUREMENTs !IR SURVEILLANCE 2ECEIVER 
 ch20.indd   40 12/20/07   1:16:50 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 
 The motion of the feed is  generally circular. The electromagnetic path within the antenna structure is designed to con-  vert the circular motion of the feed to a linear motion of the antenna beam. In some designs the  beam sweeps across a plane and then returns by the same route. 
 Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.6  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 The roughness of surfaces (especially natural ones) is difficult to describe math - ematically but easy to understand qualitatively. Thus it is easy to see that a freshly  plowed field is rougher than the same field after rain and wind have been at work  on it. 
 ORDER HEIGHT TRACKER CONSISTING OF RANGE POSITION ALPHA TRACKER  AND RANGE RATE BETA TRACKER  4HE SECOND LOOP IS THE RECEIVER GAIN CONTROL !'#  !LTIMETER HEIGHT MEASUREMENT IS GIVEN BY THE SETTING OF THE &)'52%   4HE PULSE 
 The H2S system paints on the radar screen  a rough map of the ground beneath an aircraft. The actual  photograph (left) of a radar screen shows how the picture  appears to be traced out. Coast and sea areas are clearly  marked. 
 Maximum-likelihood ISAR image autofocusing technique based on instantaneous frequency estimation. IEE Proc. Radar Sonar Navig. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°{Î PROCESSED IN GROUND 
 RESOLUTION RADAR THAT SWEEPS ACROSS THE (& BAND  MEASURING ECHO STRENGTH VERSUS TIME DELAY GROUP RANGE   TO SEE WHICH FREQUENCIES ARE ILLUMINATING ANY GIVEN REGION III  ! MINI 
 This is a known value of the radar. It is  important to know because the power returned is directly related to the transmitted power.   Prx is the power returned to the radar from a target. 
 WAVE SYSTEM DEPENDS ON THE LOCAL  APPARENT  WIND AT THE SURFACE  SO THERE CAN BE SIGNIFICANT DIFFERENCES IN WAVEHEIGHT ACCORDING  TO WHETHER THE WIND IS BLOWING WITH OR AGAINST THE CURRENT !CCORDING TO %Q   WAVEHEIGHT IS PROPORTIONAL TO THE SQUARE OF THE WIND SPEED  SO IN THE 'ULF 3TREAM  FOR EXAMPLE  WITH A CURRENT OF  KT FLOWING NORTH  A  
 THE 
 P. Papathanassiou, “A framework for investigating space-borne  polarimetric interferometry using the ALOS-PALSAR sensor,” in Proceedings IEEE Geoscience  and Remote Sensing Symposium IGARSS2005 , Alaska, IEEE, 2005. 23. 
 4ARGET $ETECTOR -4$  "LOCK $IAGRAM  0ROGRESS IN DIGITAL SIGNAL  PROCESSING TECHNOLOGY BY THE MID 
 SQUARED 
 If a quantum-limited laser must search a given solid angle O in a time ts, tht! following  relationship can be obtained85  n P A A = canst -· av e ls ,> (14.4~)  Thus the higher the frequency (shorter the wavelength) the more difficult it is for a laser to  search a large solid angle in a short time. The limited search capability of a laser means that  some sort of other cueing sensor, either electro-optical and/or radar, may be ncl.!dc<l in order  for the laser radar to acquire a target.86  The fundamental measurement capabilities of a properly designed laser radar cannot he  equalled with a microwave radar. Thus laser radars are used for those special applications  where its exceptional measurement capabilities are required, and where the need to search a  large solid-angle and an-weather operation are not important. 
 SQUARE DENSITY WITH NJ DEGREES OF FREEDOM AND DJ IS GIVEN BY  DT T JJ IN EI JIJ 
 sumed. At the longer ranges (small look-down angles), the clutter decreases with increasing altitude since range folding is less severe owing to less of the main beam intersecting the ground. At the shorter ranges, clutter increases with alti- tude since the clutter patch size on the ground increases. 
 The rangc  and doppler frequency shift can also be continuously tracked, if desired, by a servo-control  loop actuated by an error signal generated in the radar receiver. The information available  from a tracking radar may be presented on a cathode-ray-tube (CRT) display for action by an  operator, or may be supplied to an automatic computer which determines the target path and  calculates .its probable future course.  The tracking radar must first find its target before it can track. 
 Magnetrons can produce considerable electromagnetic interference across  a bandwidth much wider than the signal bandwidth (coaxial magnetrons are somewhat  better in this respect). Also, magnetrons do not have precise frequency control nor are  they able to perform precise frequency jumping. In spite of its many unfavorable characteristics, the magnetron is a tube that can be  considered for less demanding radar tasks. 
 Angle information is obtained from the pointing  direction of the antenna. The most common form of cathode-ray tube display is the plan  position indicator, or PPI (Fig. 1.3a), which maps in polar coordinates the location of the  target in azimuth and range. 
  !% *$,!%+**!)(!  *) % $ *#"       '$&$*  ) $&$*                   . Ó°È{  2!$!2 (!.$"//+  &)'52%  ,INEAR CLUTTER SEQUENCE AMPLITUDE AND PHASE FOR  HITS   PER BEAMWIDTH AFTER 4 - (ALL AND 7 7 3HRADER Ú )%%%                                           
 WAY TRANSMIT AND RECEIVE   COMPOSITE SYSTEM FREQUENCY RESPONSE  WHICH IS THE RETURN OF A NONFLUCTUATING TARGET AS A FUNCTION OF DOPPLER FREQUENCY 3YSTEM FREQUENCY RESPONSE SHOULD BE DEFINED BY THE DOPPLER PASSBAND  4HE FOCUS OF THIS SECTION WILL BE THE STABILITY REQUIREMENTS FOR  DOPPLER FREQUENCIES SEPARATED ENOUGH FROM THE CARRIER TO BE OUTSIDE THE GROUND MOV 
  
 Fourier-integral synthesis. TheFourier-integral relationship between thefield-intensity pat­ ternandtheaperture distribution wasdiscussed inSec.7.2.Thedistribution A(z)acrossa continuous aperture wasgivenbyEq.(7.14). A(z)=~LCXl~E(</J)exp(-j2nIsin</J)d(sin4». 
 At the time of Maxwell’s conclusions there was no available means to propagate or detect electromagnetic waves. It was not until 1886 thatMaxwell’s theories were tested. The German physicist, Heinrich Hertz, setout to validate Maxwell’s general equations. 
 l-10, January, 1968, PB  177017.  46. Copeland, J. 
 Itis interesting tocompute the limiting free-space range forabeacon oper- ating inconjunction with aradar setofthe characteristics assumed in our earlier radar example. Let ussuppose that the gain ofthe beacon antenna is10,and that the tranwnitted power and minimum required signal power forthebeacon arethesame asthose assumed fortheradar set. Using Eq. 
 TION IMPULSE  A SWEEP OVER A RANGE OF FREQUENCIES  RADIATION OF NOISE OVER A DEFINED BAND  OR A PSEUDORANDOM CODED SEQUENCE OF PULSES -OST '02 SYSTEMS  ALL OF WHICH NEED TO COMPLY WITH THE RELEVANT NATIONAL AND INTERNATIONAL REGULATIONS REGARDING RADIO TRANSMITTERS  OPERATE WITHIN THE RANGE OF FREQUENCIES FRO M  -(Z TO  '(Z  AND CAN HAVE A BANDWIDTH OF SEVERAL '(Z 4HE &## REQUIREMENT FOR 57" LIMITS THE RADIATED POWER TO n D"M (Z n 4HE TOPIC OF RADAR SYSTEM DESIGN IS COVERED  IN MANY TEXTS AND USEFUL INFORMATION WILL BE FOUND IN THE FOLLOWING REFERENCES $ANIELS   #OOK AND "ERNFELD  3KOLNIK  .ATHANSON  7EHNER  'ALATI  AND  !STANIN AND +OSTYLEV 4HE BURIED TARGET CAN BE A CONDUCTOR  A DIELECTRIC  OR COMBINATIONS OF BOTH 4HE  SURROUNDING HOST MATERIAL CAN BE SOIL  EARTH MATERIALS  WOOD  ROCKS  ICE  FRESH WATER  OR MANMADE MATERIALS SUCH AS CONCRETE OR BRICK ! TYPICAL '02 ACHIEVES A RANGE OF UP TO A FEW METERS  BUT SOME SPECIAL SYSTEMS CAN PENETRATE UP TO HUNDREDS OF METERS OR EVEN KILOMETERS ! FEW '02 SYSTEMS HAVE BEEN OPERATED FROM AIRCRAFT AND FROM SATELLITES TO IMAGE GEOLOGICAL FEATURES BURIED BENEATH THE 3AHARAN DESERTS AS WELL AS MEASURING THE DEPTH OF THE -OON AND FEATURES ON -ARS OR COMETS 4HE RANGE OF THE '02 IN THE GROUND IS LIMITED BECAUSE OF THE ABSORPTION THE SIGNAL UNDERGOES  WHILE IT TRAVELS ON  ITS TWO 
 1978.  52. Howells, P. 
 TheIFsignalis..::1 LORF t~ E RF IFoutput Figure9.2Principle ofthebalanced mixerbasedonthemagicT.. RECEIVERS, DISPI,AYS, AND DUPLEXERS 349  recovered by subtracting the outputs of the two diode mixers. In Fig. 
 FED REFLECTOR AND ITS ASSOCIATED BEAM ROSETTA  IE  AN OVERLAY OF BEAMS ASSOCIATED WITH EACH OF THE INDI 
 Cox and W. H. Munk, “Statistics of the sea surface derived from sun glitter,” J. 
 MENTS SUCH AS BEAMWIDTH  02&  VOLUME TO BE SCANNED  AND THE REQUIRED DATA UPDATE RATE 'IVEN THE CONSTRAINT ON THE NUMBER OF PULSES ON TARGET  ONE MUST DECIDE HOW MANY #0)S SHOULD OCCUR DURING  THE TIME ON TARGET  AND HOW MANY PULSES PER #0) 4HE  COMPROMISE IS USUALLY DIFFICULT /NE WISHES TO USE MORE PULSES PER #0) TO ENABLE THE USE OF BETTER FILTERS  BUT ONE ALSO WISHES TO HAVE AS MANY #0)S AS POSSIBLE -ULTIPLE #0)S AT DIFFERENT 02&S AND PERHAPS AT DIFFERENT 2& FREQUENCIES  IMPROVE DETECTION AND CAN PROVIDE INFORMATION FOR TRUE RADIAL VELOCITY DETERMINATION  4HE DESIGN OF THE INDIVIDUAL FILTERS IN THE DOPPLER FILTER BANK IS A COMPROMISE BETWEEN  THE FREQUENCY SIDELOBE REQUIREMENT AND THE DEGRADATION IN THE COHERENT INTEGRATION GAIN OF THE FILTER 4HE NUMBER OF DOPPLER FILTERS REQUIRED FOR A GIVEN LENGTH OF THE #0) MUST BE BALANCED BETWEEN HARDWARE COMPLEXITY AND THE STRADDLING LOSS AT THE CROSSOVER BETWEEN FILTERS &INALLY  THE REQUIREMENT OF PROVIDING A HIGH DEGREE OF CLUTTER SUPPRESSION AT ZERO DOPPLER LAND CLUTTER  SOMETIMES INTRODUCES SPECIAL DESIGN CONSTRAINTS 7HEN THE NUMBER OF PULSES IN A #0) IS LARGE  q    THE SYSTEMATIC DESIGN PRO 
 16. Cohen, W., and C. M. 
 A consideration from antenna theory is that Eq. (21.6) applies only to the far- . RANGE (nmi) BIG. 
 The frequency reference can be obtained  from the direct signal. The time reference also can be obtained from the direct signal provided  tlie distance D, between transmitter and receiver is known. If the separation between transmit-  ter arid receiver is sufficiently large. 
         
   PP n    ' 0 DE ,OOR AND 0 (OOGEBOOM  h2ADAR BACKSCATTER MEASUREMENTS FROM 0LATFORM .OORDWIJK  IN THE .ORTH 3EA v )%%% * /CEANIC %NG  VOL /% 
 12, pp 2237–2242,  December 1993.  7. D. 
 VARYING #OMPUTER CALCULATIONS  HAVE SHOWN THAT IT IS UNNECESSARY TO VARY $ IN MOST PRACTICAL SYSTEMS &)'52%  5SE OF TIME 
 C.: The Distribution of Cosmic Radio Background Radiation, Proc. IRE, vol. 46, pp. 
 CIES &IGURE  ALSO PRESENTS THE PROBABILITY OF BLANKING A USEFUL TARGET  0 4"   RECEIVED BY THE MAIN ANTENNA BEAM 4HE PROBABILITIES ARE ESTIMATED VIA  INDE 
 Any radar which employs separate antennas for transmitting and receiving might he  called bistatic, but for purposes of this disct~ssion a bistatic radar is assumed to be one in whicti  tlie separation between transmitter and receiver is comparable with the target distance. For  aircraft targets, the separations might be of the order of a few lniies to as much as several  hundred miles. For satellite targets the separation might be hundreds or even thousands of  miles. 
 Tomographic imaging and monitoring of buildings with very high resolution SAR data. IEEE Geosci. Remote Sens. 
 They may be analog or  digital with either reciprocal or nonreciprocal characteristics. Several types of ferrite pha:;e  shifters have been developed, but those that have been of interest in applications are the  Reggia-Speftcer, toroidal latching, flux drive, and dual-mode phase shifters.  Reggia-Spencer phase shifter. 
 ofpassages through .kmplitude ofemergent thelayer Ivave o 1 De-o.: B 2 —a@-P@ B 3 ~2~e3[–o~r+l p m (–a)m-jgem(:c+i p. SEC.37] USEOFABSORBENT MATERIALS 71 The minimum reflection clearly occurs when sin@=Oand cos@=–1. Hence @=(2p –l)7r p=o, 1,2, ... 
 Elec- tronic range and angle indices from sources outside ofthe diagrams can bemixed into thedouble cathode follower Vgand applied totheCRT grid. Itisassumed that both range and angle indices have positive polarity and that thepotential oftheangle-index lead iszero intheabsence ofa signal. Ifthecenter ofthesector isfixed inazimuth, agreat simplification can bebrought about bydriving amplifier Vl,Vbdirectly from apotentiom- eter which replaces theremainder ofthetop row inthe diagrams. 
 IEE (London), vol. 98, pt. Ill, p. 
 67, no. 11, 1979, pp. 1522–1553. 
 The shorter the pulse the more informa­ tion there is available from the radar, and therefore the greater will be the demands on the  information processing and display. In some high-resolution radars the number of resolution  cells might .,e greater than the capability of conventional displays to present the information  without overlap, so that a collapsing loss can result. The wide bandwidth might also mean less  dynamic range in some radar designs. 
 Dopplerresolutio/l-resolution oftargetswhosedoppler frequencies differby0.1Hzorlessis generally possible; ataradarfrequency of20MHz,0.1Hzcorresponds toadifference in relative velocity ofabout1.5knots. Although theresolution ofanHFradarispoorerinrangeandanglethanthatof microwave radar.itsresolution inthedoppler-frequency domain isquitegood.Targets not resolvable inrangeoranglecanbereadilyresolved indoppler. Aftertargetsareresolved in doppler, measurements inrangeandanglecanbemadetoagreateraccuracy thangivenbythe nominal resolution inthosecoordinates. 
 Wiley, Electronic Intelligence: The Interception of Radar Signals , Norwood, MA: Artech  House, Inc., 1986. 16. R. 
 TAL APPROACH ARE THAT LONG 
    4HE RMS VALUE OF THE SIGNAL 
 FIELD TOWARD THE CENTER OF THE FEED  WHERE THE FULL HORN WIDTH IS NOT NEEDED 4HE FEEDS DESCRIBED THUS FAR ARE FOR LINEAR 
 In the case of a material that is dry  and relatively lossless, it may be reasonable to consider that tan de is constant over that  frequency range. However, for materials that are wet and lossy such an approximation  is invalid. However, there are a number of other factors that influence the effective  penetration depth, notably the strength of reflection from the target sought, and the  degree of clutter suppression of which the system is capable. 
 canceler I I Mix / Stolo  fr  MTIANDPULSE DOPPLER RADAR105 video,justaswastheinput.Beforebipolarvideocanintensity-modulate aPPJdisplay, itmust heconverted tounipotential voltages (unipolar video)byafull-wave rectifier. ThesimpleMTlradarshowninFig.4.lbisnotnecessarily themosttypical.Theblock diagram ofamorecommon MTIradaremploying apoweramplifier isshowninFig.4.5.The significant difference betwecn thisMTIconfiguration andthatofFig.4.11>isthemanner in whichthereference signalisgenerated. InFig.4.5,thecoherent reference issupplied byan oscillator calledthecoho,whichstandsforcoherent oscillator. 
 Clarke and A. R. Subramanian, “A game theory approach to radar ECCM evaluation,” Proc. 
 499-505, 1971. 39. A. 
 Theparameter mvariesbetween 0.3and2,depending onaspect.Thesehavesometimes been calledWeinstock cases. Thechi-square distribution withm=1(Swerling cases1and2)istheRayleigh, or exponential, distribution thatresultsfromalargenumberofindependent scatterers, nooneof whichcontributes morethanasmallfractionofthetotalbackscatter energy.Although the chi-square distribution withotherthanm=1hasbeenobserved empirically togiveareason­ ablefittotheradarcrosssectiondistribution ofmanytargets,thereisnophysical scallering mechanism onwhichitisbased.Ithasbeensaidthatthechi-square distribution withm=2 (Swerling cases3and4)isindicative ofscattering fromonelargedominant scatterer together withacollection ofsmallindependent scatterers. However, itistheRicedistribution that followsfromsuchamode1.67TheRiceprobability densityfunction is l+s [a ] ( p(a)=--exp-s--{I+s)102 aay aay..!!-s(1+S)), aaya>O (2.41) wheresistheratiooftheradarcrosssectionofthesingledominant scatterer tothetotalcross sectionofthesmallscatterers, andlo()isthemodified Besselfunction ofzeroorder. 
 Ericson et al.123 generated a  stationary breaker in a small flow tunnel and compared its scattering properties with  a specular point calculation. Coakley et al.121 set up a hydrofoil in a powerful water  channel, generating a large breaking wave front that produced radar returns consistent  with Lambert’s Law, along with the polarization ratios implied by multipath reflec - tions from the undisturbed front face. These investigators, along with many others,  have been exploring radar scattering from water surfaces in ways that can be expected  to contribute significantly to our growing understanding of sea clutter. 
 In atwo-dimensional, rectangular planararray,theradiation patternmaysometimes be writtenastheproductoftheradiation patterns inthetwoplaneswhichcontain theprincipal axesoftheantenna.Iftheradiation patterns inthetwoprincipal planesareGI(O~)andG2({).,), thetwo-dimensional antenna pattern is (8.7) Notethattheangles O~andOaarenotnecessarily theelevation andazimuth anglesnormally associated withradar.15.16Thenormalized radiation patternofauniformly illuminated rec­ tangular arrayis G(O0)=sin2[Nn(dj),) sinOa]sin2[Mn(dj),) sinO,·t ~'aN2sin2[n(dj),)sinOa]M2sin2[n(dj),)sin0,.](8.8) whereN=number ofradiating elements inVadimension withspacingdandM=numher in 0,.dimension. Beamsteering. Thebeamofanarrayantenna maybesteeredrapidlyinspacewithout moving largemechanical massesbyproperly varying thephaseofthesignalsappliedtoeachelement. 
   %,%#42/.)# #/5.4%2 
 The accuracy given in range and direction should be such as to enable low altitude blind bombing or torpedo attack to be carried out. These characteristics should be retained throughoutthe full range of operational heights of the aircraft in which ASV equipment is ﬁtted. ASV should provide aircraft of a striking force despatched to attack enemy shipping with means of homing onto a beacon carried in a reconnaissance aircraft shadowingthe enemy force. 
 arid N. C. Currie: Backscatter from Ground Vegetation at Frcqirencics  Hetween 10 and lo() Gllz, I976 IEEE Ar~tetrtras utrd Proptlyurior~ Society Synlposiloi~. 
 APPROVED TRACKING SYS 
 TION AND SWATH SPAN  M TO  M  AND  KM TO  KM  RESPECTIVELY  MODE 
 Sittler, “An optimal association problem in surveillance theory,” IEEE Trans ., vol. MIL-8,  pp. 125–139, 1964. 
 Each PRF processing  interval is different, but they average out to an optimum, as shown later in Figure 5.17.  Both main and guard channel processing is required to reject false targets.25 Some  STAP processing may have been performed before this process, but traditional side- lobe and main-beam clutter is less of a limit than ground moving targets, which have  very large cross sections and exo-dopplers (i.e., doppler far enough out of main-beam  clutter that detection is not limited by the clutter return). MPRF usually has a small  amount of pulse compression (1:1 to 169:1), which still may require doppler compen - sation.65 Main and guard channels are processed in the same way. 
 The aperture efficiency is the ratio of the actual antenna directivity to the  maximum possible directivity. Maximum directivity is achieved with a uniform apcrti~re  illumination.' Although it might seem that the higher the aperture efficiency the better, apcr-  ture efficiency is seldom a suitable measure of the quality of a radar antenna. Other factors are  usually more important. 
 Wilson, J. D.: Probability of Detecting Aircraft Targets, IEEE Trans., vol. AES-8, pp. 
 G MANEUVER  ACCURACY  AS MEASURED BY THE LAG OR BIAS  IN THE PREDICTED TRACKING STATE  IMPROVES MONOTONICALLY AS THE TRACKING GAIN INCREASES TO  4HE TOTAL TRACKING ERROR CAN BE DEFINED AS THE ERROR THAT IS EXCEEDED ONLY  OF THE TIME DUE TO THE SUM OF RANDOM ERRORS AND BIAS 4HE TOTAL RANGE 
 TO 
 SENTATION IS REQUIRED IE  TO RECONSTITUTE AN IMPULSE   AS A SINGLE 
 This canbeaccomplished technically bysupplying each plane with atransponder beacon ~~rhose reply signal iscoded (Sec. 8.8) inaccordance with the altitude atwhich the plane isflying. This coding can becontrolled automa~ically byan altimeter. 
 The char - acteristics of typical indoor and outdoor test facilities are described in Section 14.4. Control of the echo characteristics of some targets is of vital tactical importance,  namely stealth . There are only two practical ways of reducing the echo: through shap - ing and radar absorbers. 
 The noise temperatures of most of the radiating sources that an antenna "sees" are frequency-dependent; therefore antenna temperature is a function of frequency. That is, antenna noise is not truly "white," but within any typical receiver passband it is virtually white. In the microwave region, it is also a function of the antenna beam elevation angle, because in this region most of the "sky noise" is the result of atmospheric radiation. 
 · · ' · . THE NATURE OF RADAR S  1.3 RADAR BLOCK DIAGRAM ANO OPERATION  The operation or a typical pulse radar may be described with the aid of the block diagram  shown in Fig. 1.2. 
 El~l~.rt.ott~c~s  (Dayton. Ohio), pp. 286--290, 1958. 
 Theseresultsapplytoaground-based array.Hthearrayisonaship,thelowerlimitofthe elevation scananglemustbelessthan0°toallowfortherollandpitchoftheship.(Avalueof -200mightbeatypicalrequirement.) Theoptimum tiltangleofthearraywouldbedifferent thanifthelowerlimitwere0°.Inoneexample 125atiltangleof27°istakenfora4-facearray covering from+90to-20°inelevation, insteadofthe35.3°ofTable8.3.Thereduction ill gainis4.3dBatthemaximum scanangleinsteadof2.8dB. Domeantenna.126129Anovelapproach toobtaining hemispherical coverage isthedome antenna depicted inFig.8.32.Aplanararrayofconventional designwithvariable phase shiftersisshownsituated belowahemispherical lenswithfixedphaseshifts.Thelens,withits fixedphaseshifts.altersthephasefrontofthefleldradiated bytheplanararraytocausea changeinthedirection ofpropagation. ThedomeactsasanRFanalogtoanopticalprism thatchanges thescanangleoftheplanararraybyafactorK(O).Forexample, aconstant value ofK=1.5extends thecoverage ofa±60°planararrayto±90°.Thelossofgainvariesinthis casefromabout3.8dBto5.4dBovertheregionofcoverage. 
 E. Clark, and W. D. 
 SURFACE REFLECTION TO BE REDUCED WHILE ENHANCING THAT FROM THE THIN PIPE OR WIRE 6ELOCITY 4HE VELOCITY OF PROPAGATION OF ELECTROMAGNETIC WAVES IN FREE SPACE IS  APPROXIMATELY   r   MSn BUT SLOWS IN A MATERIAL DEPENDING ON ITS RELATIVE PERMITTIV 
 Doviak, R. J., D. S. 
 (1 1.16) and (11.28) and by applying the Schwartz inequality. It is a  consequence of the Fourier-transform relationship between a time waveform and its spectrum  and may be derived without recourse to noise considerations. The use of the word " uncer-  tainty" is a misnomer, for there is nothing uncertain about the "uncertainty" relation of  Eq. 
 TIME 
 SISTOR IS DRIVEN INTO SATURATION  AND FOR A LARGE TRANSMITTER  THERE MAY BE NUMEROUS TIERS OF CASCADED SATURATED AMPLIFIERS 7ITH SO MANY CASCADED SATURATING AMPLIFIERS  IT BECOMES VERY DIFFICULT TO CONTROL THE RISE AND FALL TIMES AS A RESULT OF THE NONLINEARITY THAT IS INTRODUCED INTO THE POWER TRANSFER FUNCTION FOR THE TRANSMITTER #ONSEQUENTLY  AN INPUT PULSE SHAPE WITH VERY EXAGGERATED SLOW RISE AND FALL TIMES MAY BE NECESSARY TO ACHIEVE THE DESIRED OUTPUT 
   NO   PP n  !PRIL   4 (AEGER AND * * ,EE  h#OMPARISONS BETWEEN A SHAPED AND  NONSHAPED SMALL CASSEGRAIN  ANTENNA v )%%% 4RANS !NTENNAS 0ROPAG   VOL   NO   $ECEMBER   2 ! 0EARSON  % %LSHIRBINI  AND - 3 3MITH  h%LECTRONIC BEAM SCANNING USING AN ARRAY 
 Any use is subject to the Terms of Use as given at the website. Radar Receivers.  RADAR RECEIVERS  6.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 bandwidth may be, for example, specified as a 0.5 dB or 0.1 dB bandwidth. Passband  amplitude variation relative to the insertion loss is a key parameter that has potential  impact on range sidelobes and channel-to-channel tracking. 
   ,&- WITH n D" 4AYLOR WEIGHTINGo 
 vol. 61, pp. 280-298,  March. 
 Therefore, a M-unit type display is more readily understood by  the tactical radar operator looking for an optimum flight altitude for his attack. 26.4 STANDARD PROPAGATION2 Standard propagation mechanisms are those mechanisms and processes that occur in  the presence of a standard atmosphere. These propagation mechanisms are standard  refraction, free-space propagation, multipath interference (or surface reflection),  diffraction, and tropospheric scatter. 
 The reactive feed network shown in Figure 13.32 b is simpler than the matched  configuration. It has the disadvantage of not terminating unbalanced reflections that  are likely to be at least partly reradiated and thus contribute to the sidelobes. A stripline  power divider is shown in Figure 13.32 c, and a constrained optical power divider using  an electromagnetic lens is shown in Figure 13.32 d. 
 Radome Loss.  Most radars require a radome to protect the antenna from environ - mental elements and to conform to the platform’s shape. Radomes will have a loss that  may depend on the scan angle of the antenna. 
 References 9, 35, and 36 summarize much  of what has been published regarding land clutter. Not only is there a lack of published data  for the various types of land clutter, but there is not always agreement among similar data  taken by different investigators. Long9 points out that "two flights over apparently the same  type of terrain may at times differ by as much as IO dB in a0." Such variation and uncertainty  in the value of land clutter must be accounted for by conservative radar design. 
 56. J. L. 
 FORMANCE AND ANGULAR ESTIMATION RESULTS WITH OPTIMAL VALUES  AND MANY OF THESE RESULTS ARE PRESENTED LATER IN THIS SECTION )N THE ORIGINAL WORK ON DETECTORS  THE ENVIRONMENT WAS ASSUMED  KNOWN AND HOMO 
 TO 
 Note that this definition of  SAR resolution is different from the more common definition of the half-power width of  the mainlobe. With no weighting, the latter is (0.886) times the values given above; thus  the two definitions are not very different. We prefer the former definition because, for no  weighting, it results in a simpler formula without the introduction of the factor of (0.886). 
 -/" Ê 
 A. Brandes: Radar Measurement of Rainfall—A Summary, Bull. Am. 
 MeteoroL, vol. 6, pp. 243-248, 1949. 
 S. Callahan, “Satellite altimetry,” in  Satellite Altimetry and Earth Sciences , L.-L. Fu and A. 
 The n mode  is usilally preferred since it can be more readily separated from the others. The straps provide  stability since they connect all those segments of the anode which have the same potential in  the n mode and thus permit tlie tube more readily to operate in this preferred mode.  Instead of tlie liole ariri slot resollators of Fig. 
 ££°Ó  2!$!2 (!.$"//+  FOR FUTURE SYSTEM REQUIREMENTS &OR EXAMPLE  MICROWAVE POWER TUBES CONTINUE TO PRO 
 PLISHED WITH LINEAR 
 tr.(rrt.s/Or.r,t. 1 lowcvcr., wllcti N is so~llc power of 2, tllat is, N = 2. 4, 8. 
 Indeed, particularly near grazing incidence, the signal  is often described by a K, a Weibull, or a log-normal distribution.79–81 These distribu - tions are more often used to describe the variations between different returns from an  area, rather than fading. They may be thought of as describing what happens when  the area contains different s 0s, and the distribution for each is Rayleigh . Because  of this, the range of variability may be even greater than the 18 dB for a Rayleigh  distribution. 
 10.4b) was used intheAN/APS-10, giving anoutput pulse power of 10kw. The lower voltage and lower power required bythis tube enabled thedesign ofanextremely compact and simple pulser, shown inFig. 10.47. 
 SENTED BY A NARROWBAND GAUSSIAN PROCESS  4HIS IS A DIRECT CONSEQUENCE OF THE FACT  THAT   THE NUMBER OF SCATTERERS IN THE PULSE VOLUME IS LARGE       THE PULSE  VOLUME IS LARGE COMPARED WITH THE TRANSMITTED WAVELENGTH   THE PULSE VOLUME CONTAINS MULTIPLE POINT SCATTERING SOURCES  CAUSING ALL PHASES ON THE RANGE FROM  TO O TO BE COMBINED AND RETURNED AND   THE PARTICLES ARE IN RELATIVE MOTION DUE TO  TURBULENCE  WIND SHEAR  AND THEIR VARYING FALL SPEEDS  4HE SUPERPOSITION OF THE SCATTERED ELECTRIC FIELDS FROM SUCH A LARGE NUMBER OF PAR 
 912 ofenergy which would penetrate straight through would still befocused inazimuth and sowould cause spurious signals. Asolidconstruction is therefore typical ofshaped cylindrical reflectors. Paraboloid reflectors need notbesolid, since theradiation leaking through them from thepoint antenna feed isnotfocused and cannot cause sharply defined false echoes. 
 (12.14) for k = 4. Curve 2 is the constant signal contour in the diffraction  region for a signal strength equal to the free-space signal that would be received from a range  of approximately 220 nautical miles; that is, if the radar is to detect a target that lies along this  contour, it must be capable of detecting the same target in free space at a range of 220 nautical  miles. If the target were at an altitude of 200 ft, the rnaxinl~in detection range would be  reduced from 220 to about 35 nautical miles. 
 1979 , 14, 1147–1155. [ CrossRef ] ©2019 by the authors. Licensee MDPI, Basel, Switzerland. 
 Thiswassaidtoapplytoagoodoperator viewingaPPIundergoodconditions. Itsdegreeofapplicability, however, isnotclear. Itisnotunusualtofindnoaccountoftheoperator lossbeingtakenintheradarequation. 
 The processing and planar layout of these chips is somewhat standardized among manufacturers. Figure 5.1 shows a partial cross section of a typical mi- crowave bipolar power transistor chip. The structure is an NPN silicon device with a vertical diffusion profile; i.e., the collector contact forms the bottom layer of the chip. 
 Since it is expensive to get to orbit, SBRs, like other space-based systems, must be  designed to minimize mass and to maximize efficiency and longevity. Mass, power,  and lifetime emerge as driving themes that dictate conservative design, generous  margins during system implementation, and redundancy often realized by dual-string  hardware in most if not all subsystems other than the antenna. Organization of the Chapter. 
 E. Uslenghi, and T. B. 
 A. Buisson, and D. W. 
 FORMS MUST BE TRACKED WITH SUBWAVELENGTH RELATIVE ACCURACY TO CORRECT TIME 
 For example, pulse-to-pulse staggering will not provide canceling of clutter in  the ambiguous range intervals. With dwell-to-dwell staggering, an extra transmitter pulse (also known as a fill pulse)  will enable canceling of second range interval clutter. ch02.indd   39 12/20/07   1:44:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 U.S. ,41.1?ry  Missile Reseurclr UII(/ Dt~t~eloptr~e~~r COI)~I?I~II~. T~cII. 
 The only exception seems to be cathode-ray tubes (CRTs), which are less costly than large plasma displays. In radar transmitters, the transition from high-power klystrons, traveling-wave tubes (TWTs), crossed-field amplifiers (CFAs), and magnetrons to solid-state has been more gradual because the power output of individual solid-state devices is quite limited. However, compared with tubes, solid-state devices offer many advantages: 1. 
 Sensors 2019 ,19, 1920 proposed KA-DBS algorithm. Moreover, the image generated by the proposed KA-DBS algorithm is much clear than that of the other algorithms. The entropy curve of di ﬀerent imaging algorithms under di ﬀerent SNRs is shown in Figure 7. 
 CAL ARE SCARCER   7ELL 
 (iucnther. 13. I).. 
 1, pp. 37-49, 1984. 8. 
 l., 1952. (Reprinted in ref. 18.)  24. 
 42 
 The HJ-1-C’s antenna is a reflector that has an effec - tive aperture of 6 m by 2.8 m following deployment. In strip-map mode, the HJ- 1-C has a multi-look 5-m resolution over a 40-km swath, and 20-m resolution in  ScanSAR mode at 100-km swath width. SpotSAR mode is supported by controlled  yaw maneuvers of the spacecraft. 
 770–774, June 1953.  5. G. 
 The centimetric radars in S-band were developments in the UK derivedfrom H 2S Mk. II. The X-band variant ASV Mk. 
 The pencil of electrons can be focused,  . SHORT, SHARP SHOUTS 35  in a manner very similar physically to the focusing of  light, and can be made to produce a single fluorescent  _ spot of light at the end of the tube. If it is caused to  move backward and forward over the same path the spot  of light will travel up and down, or from side to side,  and if the beam is moved very rapidly, then the eye will  be unable to follow the single spot, and persistence of  vision will make us think that there is just a single line  of light. 
 )43   53 $EPARTMENT OF #OMMERCE    * - (EADRICK  * & 4HOMASON  $ , ,UCAS  3 -C#AMMON  2 (ANSON  AND * , ,LOYD  h6IRTUAL  PATH TRACING FOR (& 2ADAR  INCLUDING AN IONOSPHERIC MODEL v .AVA L 2ES ,AB -EMO 2EPT     -ARCH   , 2  4ETERS  * , ,LOYD  ' 7 (AYDON  AND $ , ,UCAS   h%STIMATING THE PERFORMANCE OF  TELECOMMUNICATION SYSTEMS USING THE IONOSPHERIC TRANSMISSION CHANNELIONOSPHERIC COMMU 
 A. Ringer and G. J. 
 Insomecasesthegeneration anddistribution ofalargenumber ofindividual phase­ shiftercommands (oneforeachelement) mightbeeconomically prohibitive. Indevising computation algorithms andcomputer hardware, advantage canbetakenofthefactthatthe phaseshillt/Jm"required attheIIIllthelementofarectangular-spaced arraycanbeseparated by rowandcolumnsinceVIm"=lIIt/Jr+Ilt/Jx'whereIll.IIareintegerscorresponding totheIIIthrow andIllhcolumn, t/J},isthephasedifference neededbetween adjacent rowstosteerthebeamin elevation. andt/Jxisthephasedifference between adjacent columns neededtosteerinazimuth: Thisissometimes calledrow/column steering. 
 vol. AES-5. pp. 
 The deﬁnition of “standard” conditionsrelates to the vertical composition of the atmosphere. Mariners may not beabletoobtainapreciseknowledgeofthisandsomustrelyonamoregeneralappreciationoftheweatherconditions,theareaoftheworld,andofthetimeof the year. While the atmospheric conditions at any one locality during a given season may differ considerably from standard atmospheric conditions, theslightly downward bending of the light and radar rays may be described asthe typical case. 
 ING   AND THE WAVELENGTH  K 7E INCLUDE ALL ANTENNA SYSTEM LOSSES IN THIS ANTENNA SYS 
 (ILL "OOK #OMPANY     P   - ) 3KOLNIK  h!N EMPIRICAL FORMULA FOR THE RADAR CROSS SECTION OF SHIPS AT GRAZING INCIDENCE v  )%%% 4RANS  VOL !%3 
 MITTER AND RECEIVER  LOOK ANGLES  WHICH ARE TAKEN AS POSITIVE WHEN MEASURED CLOCKWISE  FROM NORTH 4HEY ARE ALSO CALLED DIRECTION 
 POLAR CONVERSIONS  ARCTANGENT  ARCSINE  ARCCOSINE  AND VECTOR MAGNITUDE  THROUGH AN ITERATIVE PROCESS THAT JUST USES BIT SHIFTS AND ADDS  4HE  FOLLOWING DISCUSSION DESCRIBES THE #/2$)# ALGORITHM 4HE EQUATIONS THAT SHIFT THE PHASE OF COMPLEX NUMBER )   J1 BY AN ANGLE  P  TO  PRODUCE )   J1 ARE AS FOLLOWS  )   )COSP      
 HALF OF THE PERIOD OR AN EXACT ODD MULTIPLE THEREOF 4HE PHASE ERROR UNDER THIS CONDITION HAS ELEMENT 
 PHASED ARRAY RADAR ANTENNAS  13.696x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 exceptional stability in high winds and storms. Measuring 240 ft wide and 390 ft long,  the vessel includes a power plant, bridge and control rooms, living quarters, storage  areas, and enough floor space and infrastructure to support the X-band radar. The X-band radar itself, which sits on top of the floating platform, is the larg - est, most sophisticated phased array, electro-mechanically steered X-band radar in the  world. 
 They also review the depen - dence of the parameters defining the distribution to the rain rate and to the type  of rainfall. There is little evidence that rain with a known rate of fall has a unique  drop-size distribution, although Burrows and Attwood’s studies seem to indicate that  a certain most probable drop-size distribution can be attached to rain of a given rate  of fall.51 Results of this study are shown in Table 19.2, which gives the percentage  of total volume of rainfall occupied by raindrops of different diameters and varying  rainfall rates (millimeters per hour). In the basis of these results, the absorption cross  section of different rain rates is shown in Table 19.3. 
 TRACK DIRECTION IS  '   'A   WITH A  THE ANGLE OFF THE BEAM CENTER  WE CAN  EXPRESS A  IN TERMS OF THE DOPPLER FREQUENCY F D AS   A   FD KV  AND THE SPECTRUM IS   7F0R 2'F VDTX D   § ©¨¶ ¸·LS PL    WHERE RX IS THE HORIZONTAL RESOLUTION IN THE RANGE DIRECTION /F COURSE  THE HALF 
 2. Kharkovsky, S.; Zoughi, R. Microwave and millimeter wave nondestructive testing and evaluation—Overview and recent advances. 
 All entropies of the proposed method results are lower than others in the table. This means that the focusing of the proposed method result could outperform the other method results. The IC values of the sub-images are presented in Table 3. 
 STATE RETROFIT EASIER  THE .AVY PREFERRED NOT TO HAVE TO MODIFY THE REST OF THE SYSTEM 4HE  
 15.4  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 For a given source of asymmetry such as the wind, various parts of the spectrum  will display different directional behaviors. For example, in a fully developed sea,  the larger waves will tend to move in the direction of the wind while the smaller  waves will be more isotropic. Directional spectra are more difficult to measure and  are obtained by a variety of experimental methods, such as an array of wave staffs  to measure surface heights over a matrix of points, a multiaxis accelerometer buoy,  stereo photography, and even by processing radar backscatter signals. 
    
 However, since ISRs are sparsely distributed on the earth, despite trying our best, we only managed to ﬁnd three groups of corresponding data. The ISR data were collected from Poker Flat ISR station [ 25], and corresponding PolSAR scenes were chosen to make sure the distance from the Poker Flat ISR to the scene was less than 40 km. Three selected scenes are shown in Figure 1. 
   #OSINE SQUARED ON  D" PEDESTAL  
 , 
 135-139, IEE (London) Conference Publication no. 155.  66. 
 Itisconvenient toarrange theradar display sothat, instead ofshow- ing target range only, asinFig. 1.3, itshows the range and angular disposition ofalltargets atallazimuths. The plan-position indicator, orPPI, isthemost common and convenient display ofthis type. 
 If the system is linear, there will be a frequency  component corresponding to each target. In principle, the range to each target may be  determined by measuring the individual frequency components and applying Eq. (3.11) to  each. 
 SYSTEM FAILURE 4HE DISSIPATED HEAT COULD BE TOLERATED BECAUSE THE SYSTEM OPERATED AT A LOW DUTY CYCLE 4HE POWER COMBINING FOR EACH OUTPUT CABINET CONSISTED OF  COMBINERS 4HE  REACTIVE POWER COMBINER CONSISTED OF SEVEN GROUPS OF  COMBINERS FABRICATED IN AIR STRIPLINE USING  
 59. "Systen~ for Detecting Objects by Radio," U.S. Patent 1.981.884. 
 ELEMENT ARRAY  "UT THAT IS NOT THE END OF THE MATTERTRANSMITTER PHASE NOISE WILL BE REFLECTED BY THE DISTANT %ARTH SURFACE AND INTEGRATED ACROSS THE RECEIVER PASSBAND  RAISING THE PHASE NOISE CONTRIBUTIONS TO THE NOISE FLOOR BY A FACTOR THAT  FOR AN &- 
 RESOLUTION CLUTTER MAPS ! QUANTITATIVE DEFINITION OF INTE RCLUTTER VISIBILITY HAS NOT  YET BEEN FORMULATED &ILTER -ISMATCH ,OSS  4HE )%%% DEFINITION IS FILTER MISMATCH LOSS 4HE LOSS IN OUTPUT SIGNAL 
 G-Scope. Arectangular displayinwhichatargetappears asalaterally centralized blipwhentheradar antenna isaimedatitinazimuth. andwingsappeartogrowonthepipasthedistance tothetargetis diminished; horizontal andverticalaimingerrorsarerespectively indicated byhorizontallllH.I verti­ caldisplacement oftheblip. 
 To perform STAP, the radar should have an  array of N antennas, each with their own receiving channel and ADC. Each channel  receives M echoes from a transmitted train of M coherent pulses. Adaptivity involves  the NM echoes. 
 Now this relation will not suffice tofixthe maximum range ofdetection unless the minimum power required fordetection, Sk, isknown. This important quantity S~ti we prefer todiscuss separately, beginning inSec. 2.7below. 
 # AIRCRAFT  Î°ÎÊ , ", 
 FED REFLECTOR ARCHITECTURE DOES SUFFER FROM ONE DRAWBACK ! PARABOLA CONVERTS A SPHERICAL WAVE INTO A PURE PLANE WAVE ONLY WHEN THE SOURCE FEED  IS AT THE FOCUS )F THE SOURCE FEED  IS DISPLACED FROM THE FOCUS  THE REFLECTED WAVE IS SOMEWHAT DISTORTED AND THIS RESULTS IN GAIN LOSS AND BEAM SHAPE DISTORTION &IGURE  SHOWS THE EFFECT OF THIS DISTORTION ON THE PATTERN OF A TYPICAL CENTER 
 The result is the following rule for  selecting the antenna and target heights:  h h Ra t=λ/4 (14.21) where ha and ht are the antenna and targets heights, respectively, and R is the range to  the target. Because most test ranges have turntables or target pylons installed at a few fixed  locations relative to a permanent radar complex, the range R is usually restricted to a  few preset values. The target is installed at a height ht high enough to minimize spuri - ous interactions with the ground, yet low enough to minimize the size and complex - ity of the target support structure. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 14.40  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 of the A-12, an early prototype of the SR-71 Blackbird reconnaissance platform. 
 3.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 speed and allowable sidelobes. The two patterns may be realized by combining the  elements in separate corporate-feed structures. Figure 3.12 shows the idealized improvement factor as a function of normalized  aperture movement for a double-delay canceler. 
 There are many new topics not found in the original, and over half of the 25 chapters were written by authors who did not participate in the first edition. The continued growth in radar capability and applications is reflected in much of the new material included in this second edition. The following are some of the many new radar advances that have occurred since the original edition (listed in no particular order): • The use of digital techniques that allow sophisticated signal processing in MTI and pulse doppler radars, as well as digital data processing to perform automatic detection and tracking. 
 used as the transmit array to avoid high-power switching circuits. The separation of the subarrays d must equal 2VgTp to compensate for the transmit phase-center displacement. This allows A1 — A'2 to be paired and then A\ to be paired with A"2, where A1 is displaced from A2 by d. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation. 26.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 To assist the AREPS user, these and other input windows have many “canned”  default values combined with many unit options. 
 BEAM RADIATION PATTERN AND THE RESPONSE OF  A POINT SCATTERER FOR TWO SUCCESSIVE PULSES WHEN THE ANTENNA IS SCANNING )T IS SEEN THAT THE SIGNALS RETURNED WOULD DIFFER BY  $' P   4HIS RESULTS IN IMPERFECT CANCELLATION DUE  TO SCANNING 4HE AVERAGE EFFECT ON THE IMPROVEMENT FACTOR CAN BE OBTAINED BY INTEGRAT 
 A conceptual scheme showing the interaction of scheduling and  tracking is shown in Figure 24.13, where rk, bk, ek are the range, bearing, and eleva - tion measurements at tk; SNRk is the observed SNR at tk; tk+1 is the commanded time  for the next target observation; rk+1|k, bk+1|k, ek+1|k are the predicted range, bearing, and  elevation for beam pointing control at tk+1; Wk+1 is the waveform selection at tk+1; bk+1  is the detection threshold for the dwell set at tk+1; and Xk|k, Pk|k are the target filtered  state estimate and covariance matrix at tk given all the radar measurements up to  tk.   FIGURE 24.13  Interaction of radar scheduler and tracking filterRADAR MODEL SCHEDULERTIME DELAYtk, rk, bk, ek, SNRkSURVEILLANCE SCENARIO TRACKING FILTERtk-1, Xk-1/k-1, Pk-1/k-1 rk+1/k, bk+1/k ek+1/k tk, Xk/k, Pk/ktk+1, Wk+1, bk+1 ch24.indd   44 12/19/07   6:01:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
    .OVEMBER   PP n  ' 'RASSO AND 0 & 'UARGUAGLINI  h#LUTTER RESIDUES OF A COHERENT -4) RADAR RECEIVER v  )%%%  4RANS  VOL !%3 
 LATION IS DISASTROUS AND MAJOR EFFORTS ARE BEING MADE BY THE INTERNATIONAL COMMUNITY TO CLEAR THE PROBLEM -OST DETECTION IS DONE WITH METAL DETECTORS  WHICH RESPOND TO THE LARGE AMOUNT OF METALLIC DEBRIS IN ABANDONED BATTLEFIELD AREAS AND HENCE HAVE DIFFICULTY IN DETECTING THE MINIMUM METAL OR PLASTIC MINE '02 TECHNOLOGY IS BEING APPLIED TO THIS PROBLEM AS A MEANS OF REDUCING THE FALSE ALARM RATE AND PROVIDING IMPROVED DETECTION OF LOW 
  
 FILTER GAIN 4HE AMOUNT OF LOSS DEPENDS ON THE MAGNITUDE OF THE INTERFERENCE AND IS ACCOUNTED FOR IN THE SIGNAL 
 Brunfeldt and F. T. Ulaby, “An active radar calibration target,” Dig. 
 PULSE CANCELERS AS A FUNCTION OF  R,   THE RATIO OF THE RMS CLUTTER AMPLITUDE TO THE LIMIT LEVEL (ITS PER ONE 
 UP CONVERSION AND DEMODULATIONMODULATION OF THE SIGNAL PERFORMED IN THE $2&- DEVICE ! DETAILED ANALYSIS OF THIS KIND OF ERRORS IS IN "ERGER .   %,%#42/.)# #/5.4%2 
 Ó£°Ón  2!$!2 (!.$"//+  FLAT  CYLINDRICAL  OR CONICAL IN CROSS  SECTION  FORMING A 6 STRUCTURE IN WHICH RADIATION  PROPAGATES ALONG THE AXIS OF THE 6 STRUCTURE !LTHOUGH RESISTIVE TERMINATION IS USED   THIS TYPE OF ANTENNA HAS A DIRECTIVITY ON THE ORDER OF n D" DEPENDING ON SIZE HENCE  USEFUL GAIN CAN STILL BE OBTAINED EVEN WITH A TERMINATING LOSS ON THE ORDER OF &)'52%   % 
 Wang, J.; Liu, X. SAR minimum-entropy autofocus using an adaptive-order polynomial model. IEEE Geosci. 
 74–79, 1980.  2. D. 
 CIES  3 BAND  CM  AND 8 BAND  CM   AND TWO RESOLUTIONS   M AT  LOOKS  AND  M AT  LOOKS 4HE ,2/ RADAR ALSO INCLUDES AN INTERFEROMETRIC MODE  WHICH REQUIRES A CONTINUOUS 02&  IN CONTRAST TO THE BURST PLAN USED FOR THE OTHER MODES "OTH HAVE MODERATE INCIDENT ANGLES ^  DEGREES   MODERATE SWATH WIDTHS  KM TO  KM   AND  OPERATE FROM LOW ALTITUDES  KM AND  KM  RESPECTIVELY  'IVEN THE APPLICABLE SMALL RANGE 
 J.Alter:Automatic Detection andIntegrated Tracking. IEEE1975IIltCrlllItivlla[ RadarCOII!i.'/'{'lIce. pp.391-395. 
 MTI typically eliminates clutter by passing  the received returns from multiple coherent pulses through a filter with a stopband  placed in spectral regions of heavy clutter concentrations. Moving targets with dop - pler frequencies outside the stopband are passed onto detection processing. Pulse  doppler radars, on the other hand, resolve and enhance targets within a particular  doppler band while rejecting clutter and other returns outside the doppler band of  interest. 
 Intheradar-Illeteorology literature, theradarpulse-extent It (inunitsoflength) isortenusedinsteadofcrinthisequation. Thefactornj4isincluded to account fortheelliptical shapeofthebeamarea.Insomeinstances thisfactorisomitted for convenience; however. radarmeteorologists almostalwaysincludeitsincetheyareconcerned withaccurate measurement ofrainfallrateusingtheradarequation. 
 There is a value of Bn that optimizes the output signal-to-noise ratio, as indicated by Eq. (2.8), and this optimum bandwidth is inversely proportional to the pulse length T. (This statement applies to pulse compression radars as well as to others if T is, in this context, the compressed pulse length, since it is the compressed pulse that is amplified in the receiver. 
 A merg - ing algorithm34 often used is the adjacent-detection merging algorithm, which decides  whether a new detection is adjacent to any of the previously determined sets of adjacent  detections. If the new detection is adjacent to any detection in the set of adjacent detec - tions, it is added to the set. Two detections are adjacent if two of their three parameters  (range, azimuth, and elevation) are the same and the other parameter differs by the  resolution element: range cell ∆R, azimuth beamwidth q, or elevation beamwidth g. 
 Barbarossa, A. Farina, and L. Timmoneri, “Monopulse estimation of target DoA  in external fields with adaptive arrays,” IEEE Symp. 
 SCEND DUCT BOUNDARIES &OR EXAMPLE  AN AIR TARGET THAT WOULD NORMALLY BE DETECTED MAY BE MISSED IF THE RADAR IS WITHIN OR JUST ABOVE THE DUCT AND THE TARGET IS JUST ABOVE THE DUCT 4HIS AREA OF REDUCED COVERAGE IS KNOWN AS A RADAR HOLE OR SHADOW ZONE !NOTHER INTERESTING FEATURE OF SURFACE 
   (& /6%2 
 BAND RADIATION v  -ICROWAVE *  VOL   PP n   $ECEMBER   ! ! !CKER  h%LIMINATING TRANSMITTED CLUTTER IN DOPPLER RADAR SYSTEMS v  -ICROWAVE *  VOL    .O   PP n  .OVEMBER   - 4 .GO  6 'REGERS 
 67. ('roney, J.: Doubly Dispersive Frequency Scanning Antenna, Microwave J., vol. 6, pp. 
 Thering-loop slow-wave circuitwhichconsists ofequallyspacedringsandconnecting bars,isalsorelatedtothehelixandthering-bar.Itisclaimed 14tobepreferred fortubesinthe powerrangefromIto20kW,asforlightweight airborne radarorasdriversforhigh-power tubes.Thering-loop circuitisnotbothered bythebackward-wave oscillations oftheordinary helixorthe"rabbitear"oscillations whichcanappearincoupled-cavity circuits. Thehelixhasbeenoperated athighaverage powerbypassingcooling fluidthrough a helixconstructed ofcoppertubing.43Thebandwidth ofthistypeoffluid-cooled helixTWT canoealmostanoctave,anditiscapableofseveraltensofkilowatts averagepoweratLband withadutycyclesuitahle forradarapplications. Apopular formofslow-wave structure forhigh-power TWTsisthecoupled-cm'ity circuit. 
 Since the relative motion between the aircraft and ground is small, the effect of tht:  doppler frequency shift may usually be neglected.  The band from 4.2 to 4.4 GHz is reserved for radio altimeters, although they have in the  past operated at UHF. The transmitter power is relatively low and can be obtained from a CW  magnetron, a backward-wave oscillator, or a reflex klystron, but these have been replaced by  the solid state transmitter. 
 %   
 10.45 aredefined asfollows: L1=leakage inductance due toflux from primary current which fails tolink with secondary and represents effect ofmagnetic energy stored between windings byload current. C.=effect ofelectrostatic energy stored inthe primary-secondary distributed capacity. Iftransformer ispulsed from low-voltage endCD must becharged through Lt. 
 NewYork.1970.fig.30. 83.Fox.J.(ed.):"Proceedings oftheSymposium onSubmillimeter Waves." Polytechnic Pressofthe Polytechnic Institute ofBrooklyn. Brooklyn. 
 The  tracking bandwidth in some systems might be made variable or even adaptive to conform  i~t~to~ii;itically to tlic target cot~ditiotis.  Another restriction on the tracking bandwidth is that it should be small compared to the  lowest tiatt~ral resonant frequency of tlie antenna and servo system including the structt~re  foundation, in order to prevent the system from oscillating at the resonant frequency. The  shaded region in Fig. 
 2.1), gain has necessarily been sacrificed; ofcourse this isinevitable,. SEC,2.5] BEAMS OFSPECIAL SHAPES 23 fortheradiated energy has been spread out over alarge solid angle. Consider the problem ofdesigning aradar setwith the requirement imposed that the vertical beamwidth beB. 
 Substituting Eq.(10.1)intoEq.(10.4)gives II(t)=GafooS*U)exp[-j2rif(tl -t)Jdf -00 SinceS*(f)=S(-f),wehave h(t)=GafooSU)exp[j2nf(tt-t)]df=Gas(tt-t) -00(10.5) (10.6) Aratherinteresting resultisthattheimpulse response ofthematched filteristheimageof thereceived waveform; thatis,itisthesameasthereceived signalrunbackward intime starting fromthefixedtime(I'Figure10.1showsareceived waveform s(t)andtheimpulse response II(r)ofitsmatched filter. Theimpulse response ofthefilter,ifitistoberealizable, isnotdefinedfort<O.(One cannothaveanyresponse beforetheimpulse isapplied.) Therefore wemustalwayshave ( <(I'Thisisequivalent tothecondition placedonthetransfer functionH(f)thattherebea phaseshiftexp(-j2rr.ftI)'However, forthesakeofconvenience, theimpulse response ofthe matched filterissometimes writtensimplyass(-t). Derivation ofthematched-filter characteristic. 
 Any use is subject to the Terms of Use as given at the website. Airborne MTI. 3.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 FIGURE 3.18  DPCA clutter residue versus angle for normalized displacement, Vn = 0.04,   and normalized scanning motion, Wn = 0.04 FIGURE 3.19  DPCA improvement factor versus normalized platform motion, Vn, as a function of normal - ized scanning motion, Wnpath, and the other, C2(q ), which is added to the sum pattern and fed to the delayed path  as shown in Figure 3.20. The procedure was developed for a single-delay canceler and   a nonscanning antenna. 
 MTI AND PULSE DOPPLER RADAR 109  V,  0  C  --"' .  "CJ  Q.)  OJ a  V,  "CJ 1,000  C  Li  +-V,  L  ii:  10 100 1,000  Maximum unambiguous range, nautical miles  Figure 4.8 Plot of MTI radar first blind speed as a function of maximum unambiguous range.  Uouble cancellation. 
 QUENCY AND DESCRIBES HOW THE BEAM MOVES AS THIS FREQUENCY IS CHANGED (OWEVER  MOST RADARS ARE PULSED AND RADIATE OVER A BAND OF FREQUENCIES &OR A BEAM  SCANNED FROM BROADSIDE  EACH SPECTRAL COMPONENT IS STEERED TO A SLIGHTLY DIFFERENT DIREC 
 , I I II,--r-I--+-1---'----;--; 1.2;' ,. ,: \I I _i..~ , T"" [-------;- I·-T-f---+---r---+--+--i-----l-- 10.:. I..'; I 1 ~+_I- .....""""_ 08.;:.." MEANELEVATIONERROR! I I,,,; Ir'!!WITHl I I'TTT I I O.':,16 ~~L?~~ ~~~l~~K,~~~·~'~-.~~~~~~~~~~~I~~T~:~~~~I-l~-l~~l-~'-~:-.~I===~~~~. 
 SCAN TARGET  MEASUREMENTS TAKEN AS THE ANTENNA SAMPLES THE TARGET PATHS IV  4HE MULTIFUNCTIONAL PHASED 
 35. F. J. 
 To begin, a fully adaptive array architecture is shown in Figure 3.23.  This is for a linear array antenna with a distributed transmitter and digital receivers con - nected to each antenna element. The adaptive weight solution is developed based on at  least 2 × N × M vector samples ( r) of length M (antenna elements) by N (pulses). 
 SCAN PULSE STAGGERING IS USED   OF THE DESIRED TARGETS WOULD BE MISSING ON EACH SCAN OWING TO DOPPLER CONSIDERATION ALONE 4HIS MIGHT BE INTOLERABLE FOR SOME APPLICATIONS  o  4HE CHOICE BETWEEN PULSE 
 This may be accom-  plished with a frequency discriminator and a tunable oscillator to maintain the received signal  in the center of a narrow-band filter. It is also possible to use a phase-lock loop, or phase-  sensitive discriminator whose output drives a voltage-controlled oscillatar to hold its phase in  step with the input signaL2 Tracking the doppler frequency shift with the equivalent of a  narrow-band filter just wide enough to encompass the frequency spectrum of the received  signal allows an improvement in the signal-to-noise ratio as compared with wideband proczs-  sing. It can also provide resolution of the desired moving target from stationary clutter. 
 The EBS is claimed to  be broadband and to have high gain (25 to 35 dB), high efficiency (50 percent), and long life. At  1 GHz, an EBS amplifier might be capable of a peak power of 2 to 3 kW, and an average  power of about 200 W. The EBS has decreasing capability at the higher frequencies. 
 The problem of modeling sea scatter will be discussed sepa - rately in a later section. ch15.indd   2 12/15/07   6:16:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 K., E. J. Dodsworth, and M. 
 The diffraction coefficients are  Xn n n ni s=− −sin( ) cos( ) cos[( ) ]π π/ / / /f f (14.18)  Yn n n ni s=− +sin( ) cos( ) cos[( ) ]π π/ / / /f f (14.19) where fi and fs are the angles of the planes of incidence and scattering, as measured  from one face of the wedge (say, the illuminated one), and n is the exterior wedge angle  normalized with respect to p. When these expressions are evaluated for the case of a  flat metal edge viewed edge-on with the incident polarization in the plane of the plate,  they yield the edge-on formula s = L2/p  listed in Table 14.1. Keller’s diffraction coefficients are based on an approximation of the exact solution  for an infinite (two-dimensional) metal wedge as applied to a three-dimensional prob - lem.36 Although this adaptation of a two-dimensional solution to the three-dimensional  world is reasonably effective most of the time, the diffraction coefficients inconve - niently blow up just when needed most. 
        
 The mixed inﬁnite norm takes the number of non-zero elements of the pixel point with the largest amplitude in each image as the joint sparsity, and can also ensure that scattering points in the reconstructed sub-aperture images are aligned. 3.3. Optimal Solution Algorithm Constrained by Joint Sparse According to the constructed global sparsity constraint function, the problem of InISAR imaging solution is transformed into the problem of multi-channel joint sparse optimal reconstruction problem: ming1,g2/bardblg/bardblp,0s.t./braceleftBigg /bardbls/prime 1−A/prime 1g1/bardbl2 2≤ξ /bardbls/prime 2−A/prime 2g2/bardbl2 2≤ξ, (17) where, ξis determined by the minimum noise level of each channel to ensure that each channel can generate the target image. 
 SIONAL STRUCTURE OF RAINFALL FROM THE SURFACE TO AN ALTITUDE OF  KM 7HEN COMBINED WITH DATA FROM THE PASSIVE MICROWAVE RADIOMETER 4-)   02 DATA SUPPORT IMPROVED ACCURACY OF RAINFALL RETRIEVALS 4HE RADARS + U BAND ^ CM  FREQUENCY IS ABOUT THREE  TIMES HIGHER THAN MOST SURFACE 
 SWEPT SAW 
 . In Brit.ain the development of radar began later than in the United States.8-11 But  because they felt the nearness of war more acutely and were in a more vulnerable position with  respect to air attack, the British expended a large amount of effort on radar development. By  the time the United States entered the war, the British were well experienced in the military  applications of radar. 
 Coaxial Magnetron.25 A significant improvement in the power, efficiency, sta - bility, and life of the original form of the magnetron occurred with the introduction of  the coaxial magnetron. The key difference is the incorporation of a stabilizing cavity  surrounding the conventional magnetron cavities, with the stabilizing cavity coupled  to the magnetron cavities so as to provide better stabilization. The frequency of a  coaxial magnetron can be changed by mechanically moving one of the end plates,  called a tuning piston, of the stabilizing cavity. 
 If the  main beam cannot he made narrow because of constraints on the antenna size, an auxiliary  antenna can be employed to create a notch in the main-beam radiation pattern in the direction  of the jammer. With adaptive cir~uitry similar to that of the sidelobe canceler, this mai11-hea,11  notch can be automatically adjusted to be maintained in the direction of the jammer.  Multiple radars viewing the same coverage in a coordinated manner can provide some  benefit against a jammer since it is unlikely that jamming power can be distributed uniformly  in space. 
 The received  levels are kept below saturation levels, typically with a clutter AGC in search and a  target AGC in single-target track, to prevent spurious signals, which degrade perfor - mance, from being generated. Noise Automatic Gain Control (NAGC).  The NAGC attenuator is used to set the  thermal noise level in the receiver to support the required dynamic range, as discussed  in Section 4.3. 
 Dec.. 1941.  X. 
 Thus the bistatic radar  docs not " overdetect " at short ranges as does monostatic radar.  'I'lic ~lloriostatic radnr is wcll silitcd to volutilctric coverage. If the bistatic radar were to  provide voli~metric coveragc with directive antenna beams, the transmitting and receiving  hearns would have to be scanned in synclironism. 
 Yang, X.; Wang, Y.; Qi, Y.; Tan, W.; Hong, W. Experiment Study on Deformation Monitoring Using Ground-Based SAR. In Proceedings of the Asian-Paciﬁc Conference on Synthetic Aperture Radar (APSAR 2013), Tsukuba, Japan, 23–27 September 2013. 
 F. E. Nathanson, Radar Design Principles,  2nd Ed. 
 The array is fed from a solid-state transmitter and trans - mits a single fan beam in elevation optimized for maximum gain at low altitudes. On  receive, the array output is combined into six simultaneous narrow elevation beams  that cover from 0 to 20 °. Each receive beam is processed in a digital receiver. 
     2 &ANTE AND 3 $HAR  h! MODEL FOR TARGET DETECTION WITH OVER 
 C. Macdonald: Elevated Duct Propagation in the Tradewinds, IRE Trat~s.,  vol. AP-9. 
 (ILL  )NC       PP n   * " 4SUI   $IGITAL 4ECHNIQUES FOR 7IDEBAND 2ECEIVERS  ND %D  2ALEIGH  .# 3CI4ECH 0UBLISHING  #OMPANY    PP n  , 0 'OETZ AND 7 ! 3KILLMAN  h-ASTER OSCILLATOR REQUIREMENTS FOR COHERENT RADAR SETS v IN  )%%% 
 The received signal and a portion of the  transmitter heterodyne in the detector (mixer) to yield a difference signal  (3.6)  OJ OJ  11 I u u ::, ::, -~ -ci. a. E  Id E Id- <{ <{  fo lo· lo  Frequency Frequency Frequency  (a) (bl (c)  Figure 3.7 Spectra of received signals. 
 Figure 4). Tunable length tapered tails were used to control aliasing effects without reducing severely the azimuth resolution of the focused image, both in the range and azimuth reference functions. Figure 5reports the obtained reference functions used to focus on range and azimuth the raw data. 
 B. Trizna: Small Boat Radar Cross Sections, Naval Res. Lab. 
 Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft.  MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 and acquisition. If the target is a periscope or person in a life raft then 0.3 m resolu - tion might be used since the RCS might be less than 1 m2 and smoothing is especially  important. 
 Ê-9-/ 
 Ishikura, I. Takenake, K. Asano, N. 
 This requires asingle-axis gyro transmitter for the roll axis, and but one servoamplifier and follow-up channel. Roll stabilization would beappropriate inlarge aircraft forwhich the pitch component might benegligible ortolerable. Indeciding between aroll and aplatform stabilizer the accuracy requirements must bebalanced against theweight added bythepitch channel. 
 Atmicrowaves thebackscatter fromraincanbeexplained according totheRayleigh scattering modelwiththereflectivity varying asthefourthpowerofthefrequency (Sec.13.7). Inthemillimeter-wave region,thedropsizesoftheraindrops spanboththeRayleigh andthe Miescattering regionssothatadirrerence inbehavior canbeexpected. Experimental measure­ mentsindicated that,ontheaverage, theradarbackscatter at9.4and35GHzappeared to followtheRayleigh scattering law.79.102 Deviations fromRayleigh werefoundat70and 95GHz.andthebackscatter at95GHzwasobserved tobelessthanat70GHz.Theback­ scatter ~t..millimeter waveswasfoundtodepend onthedropsizedistrib~tion ofthe pricipitation.102Eventhoughtherainrateswerethesame,thebackscatter fromraincontain­ ingdrops2to6mmindiameter wasapproximately 10dBgreaterthanraincontaining drops 1mmindiameter orless.Theamplitude fluctuations oftherainbackscatter wereapproxi­ matedbyalog-normal probability distribution overtherangefrom9.4to94GHzandatrain ratesfrom1mm/hto60mm/h.Thevariance (andstandard deviation) ofthelog-normal distribution wasindependent ofrainrateanddecreased withincreasing frequency. 
 80. Hitney, H. V., and J. 
 PULSE PHASE ADVANCE OF AN ELEMENTAL SCATTERER AS SEEN BY THE RADAR RECEIVER  &)'52%  %FFECT OF PLATFORM MOTION ON THE -4) IMPROVEMENT FACTOR  AS A FUNCTION OF THE FRACTION OF THE HORIZONTAL ANTENNA APERTURE DISPLACED PER  INTERPULSE PERIOD  6X4PA. 
 The input to the mixer is a signal of known frequency f, and known phase 40  plus its accor~lpariyirig noise. The reference-oscillator signal is assumed to have the same  frequency and phase as the input signal to be detected. The output of the mixer is followed by a  low-pass filter which allows only the d-c and the low-frequency modulation components to  pass while rejecting the higher frequencies in the vicinity of the carrier. 
 A log  gives speed through the water  (STW). This can be either a conventional rotating  transducer driven by the movement through water or else an acoustic transducer  measuring the doppler of the reflected signal. The latter can be set to assess speed  either relative to the surrounding water (STW) or relative to the seabed, i.e., speed  over ground  (SOG). 
 Data rate is defined here as the revisit time in a scanning-beam radar, and in a  r~iultiple-bean1 radar it is the time over which the total number of pulses are integrated. In  practice. postdetection iritegration is usually employed and there will be a finite integration  loss. 
 With a different value of current pulse, a different value  of remanent magnetization can be obtained and therefore a different phase shift. In this  manner. the ferrite toroid is basically an analog device that can provide any phase increment. 
 3 EVEN THOUGH THERE ARE SIGNIFICANT DIFFERENCES THAT AIR SHOW VISI 
 LENS REFLECTORS  METAL PLATES  CORNER REFLECTORS  OR ACTIVE RADAR CALIBRATORS !2#SACTUALLY REPEATERS    /F THE PASSIVE CALIBRATORS   THE ,UNEBURG 
 The zeroth tap couples the distorted compressed pulse, unchanged except for delay, to the bus. The other taps make it possible to "buck out" distortion echoes of arbitrary phase and amplitude over a compensation interval equal to the total line delay. Reducing time sidelobes to an acceptable level is in effect synthesizing an equalizing filter, which makes the spectrum of the output pulse approach the ideal one described above. 
 (U.S.S.R ), vol. 27, no. 8, pp. 
 If the image frequency of a mixer is presented with the proper  reactive termination (such as an open or a short circuit), the conversion loss and the noise  figure can be l to 2 dB less than with a "broadband" mixer in which the image frequency is  terminated in a matched load. 6• 1° The reactive termination causes energy converted to the  image frequency to be renected back into the mixer and reconverted to IF.16•24  Both the sum and the image frequencies can be reflected back to the diode mixer to  achieve a lower conversion loss, but a number of adjustments are required for good results.24  One method for terminating the image in a reactive load is to employ a narrow bandpass filter,  or preselect or, at the RF signal frequency. A limitation of this approach is that it is not suitable  for very wide bandwidths. 
 LATORS WITH RANDOM PHASES AND UNRELATED FREQUENCIES 4HIS SAME MODEL OF A GROUP OF RANDOMLY PHASED  DIFFERENT 
 The dynamic range is greater since digital MTI processors  do not experience the spurious responses which limit signals in acoustic delay lines to about 35  to 40 dB above minimum detectable signal leveL2' (A major restriction on dynamic range in  a digital MTI is that imposed by the A/D converter.) In an analog delay-line canceler the delay  time and the pulse repetition period must be made equal. This is simplified in a digital MTI  since tlie timing of the sampling of the bipolar video can be controlled readily by the timing of  the transmitted pulse. Thus, different pulse repetition periods can be used without the necessity  of switching delay lines of various lengths in and out. 
 MATELY THE PRODUCT OF THE NUMBER CALCULATED FROM %Q  AND THE NUMBER OF GROUND CELLS AVERAGED &IGURE  SHOWS SOME EXAMPLES OF THE EFFECT  OF THE ANGLE OF INCI 
 B. Lewis, F. R. 
 Urban area remote sensing from L-band PolSAR data using time-frequency techniques. In Proceedings of the 2007 Urban Remote Sensing Joint Event, Paris, France, 11–13 April 2007; pp. 1–6. 
 34!4% 42!.3-)44%23   ££°ÎÎ BANKS OF FINAL OUTPUT MODULES   K7  WAS PROVIDED FROM THE COMBINED OUTPUTS OF   MORE IDENTICAL MODULES IN THE DRIVER GROUP 0REDRIVERS AND A REDUNDANT PREAMPLIFIER WERE USED AS PRECEDING DRIVE STAGES 4HE POWER AMPLIFIER MODULE CONSISTED OF TEN IDENTICAL SILICON BIPOLAR POWER TRAN 
 The ITU regulations limit RTEs to an EIRP of 10 watts, with a minimum  gain of 50 dB. ch22.indd   27 12/17/07   3:02:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 BEAM AZIMUTH ANGLE IS AT ZERO  ANY HEAD 
 Figure 8.24 shows an arrangement of this type.  Each of the  individual signals rests at the summing unit in suc h a way that all values are positive when the  last bit arrives.  . 
 Stark, L., R. W. Burns, and W. 
 8.22, is fed from a primary feed just as a lens  antenna. An array of antenna elements collects the radiated energy and passes it through the  phase shifters which provide a correction for the spherical wavefront, as well as a linear phase  shift across the aperture to steer the beam in angle. Another set of elements on the opposite  side of the structure radiate the beam into space. 
 Radarechoesfromland,sea,rain,birds,andothersuchobjectsarenotalwaysundesired. Reflections fromstormclouds,forexample, canbeabothertoaradarthatmustseeaircraft, butstormcloudsarewhattheradarmeteorologist wantstoseeinordertomeasure rainfall rateoveralargearea.Thebackscatter echoesfromlandcandegradetheperformance ofmany radars;butitisthetargetofinterestforaground-mapping radar,forremotesensingofthe earthresources, andformostsynthetic-aperture radars.Thusthesameobjectmightbethe desiredtargetinoneapplication, andtheundesired clutterechoinanother. Inthischapter, theechoesfromland,sea,andweatherwillbeconsidered onlyfortheir harmfuleffects;thatis,ascluttertobeavoidedoreliminated. 
 Due to the large amount of densely distributed coherent points, the search operation of the genetic algorithm was extremely time consuming; thus, we masked the targets distributed along the route as our observed pixels. According to our in situ investigation and the design materials 238. Sensors 2019 ,19, 3073 collected from the highway construction company, Fuoshan, China, we found a section of the test highway which was still under road surfacing from November 2014 to December 2014, and the whole route was opened to tra ﬃc in January 2015. 
 Meymaris, and R. J. Keeler, “Range-velocity mitigation via SZ phase coding  with experimental S-band radar data,” in 31st Conf. 
      PP n    0 ( 9 ,EE  * $  "ARTER  + , "EACH   # , (INDMAN  "  - ,AKE  ( 2UNGALDIER   * # 3HELTON   ! " 7ILLIAMS  2 9EE  AND ( # 9UEN  h8 BAND MICROWAVE SCATTERING FROM OCEAN WAVES v   * 'EOPHYS 2ES  VOL   NO #  PP n  &EBRUARY    - +ATZIN  h/N THE MECHANISMS OF RADAR SEA CLUTTER v 0ROC )2%  VOL   PP n  *ANUARY   , " 7ETZEL  h! MODEL FOR SEA BACKSCATTER INTERMITTENCY AT EXTREME GRAZING ANGLES v  2ADIO 3CI   VOL   PP n    ) - (UNTER AND 4 " ! 3ENIOR  h%XPERIMENTAL STUDIES OF SEA SURFACE EFFECTS ON LOW ANGLE  RADARS v 0ROC )%%  VOL   PP n    ( 3ITTROP  h8 
 Thayer: Models of Atn~osplteric Radio Refractive Index, Proc. IRE, vol. 47,  pp. 
 The  open-ended waveguide as the feed for a paraboloid directs the energy better than a dipole, and  the phase characteristic is usually good if radiating in the proper mode. A circular paraboloid  might be fed by a circular, open-ended waveguide operating in the TE,, mode. A rectangitlar  guide operating in the TElo mode does not give a circularly symmetric radiation pattern since  the dimensions in the E and H planes, as well as the current distribirtions in tllese two plancs,  are different. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 17.6  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 Then crossrange resolution is approximately as follows for the different modes dis - cussed previously: SLAR: 1500 m DBS: 150 m Unfocused stripmap SAR: 27 m Stripmap SAR: 1 m Spotlight SAR: 0.3 m  17.4 SAR RESOLUTION In this section, we discuss SAR resolution in more detail. 
 There are many targets of interest in the imaging scene, including civilian vehicles, a top-hat, trihedrals, and dihedrals. 256. Sensors 2019 ,19, 346 4.1. 
 7378, Washington, D.C., Mar. 17, 1972.  47. 
 buttheearactsasaselective bandpass filterwithapassband oftheorderof50Hz centered aboutthesignalfrequency.2 Thenarrow-bandpass characteristic oftheearresultsin aneffective increase inthesignal-to-noise ratiooftheechosignal.Withsubsonic aircraft targetsandtransmitter frequencies inthemiddlerangeofthemicrowave frequency region,the doppler frequencies usuallyfallwithinthepassband oftheear.Ifaudiodetection weredesired forthosecombinations oftargetvelocity' andtransmitter frequency whichdonotresultin audibledoppler frequencies, thedoppler signalcouldbeheterodyned totheaudiblerange.The doppler frequency canalsobedetected andmeasured byconventional frequency meters, usuallyonethatcountscycles.Anexample oftheCWradarprinciple istheradioproximity (VT)fuze,usedwithgreatsuccessduringWorldWarIIforthefuzingofartillery projectiles. It mayseemstrangethattheradioproximity fuzeshouldbeclassified asaradar,butitfulfillsthe samebasicfunction ofaradar,whichisthedetection andlocation ofreflecting objectsby "radio" means.J·4 Isolation between transmitter andreceiver. Asingleantenna servesthepurpose oftransmission andreception inthesimpleCWradardescribed above.Inprinciple, asingleantenna maybe employed sincethenecessary isolation between thetransmitted andthereceived signalsis achieved viaseparation infrequency asaresultofthedoppler effect.Inpractice, itisnot possible toeliminate completely thetransmitter leakage. 
 Figure 25.15 shows the corresponding block diagram. The magnitude of the fre - quency response on line 4 of Figure 25.14 is neither an even nor an odd function,  so the corresponding impulse response is neither purely real nor purely imaginary. FIGURE 25.12  Various signals sampled at 300 MHz: ( a) 75 MHz cosine and –sine LO signals,   (b) 75 MHz IF tone, and (c) result of multiplying ( a) samples by ( b) samplesILO QLO+1 0 –1 IF+1 0 –1 I+1 0 –1QI QI QI Q(a) (b) (c) FIGURE 25.13  75 MHz tone sampled at ( a) 100 MHz (4/3 × IF) and ( b) 60 MHz (4/5 × IF)I Q–I–Q I Q–I–Q I–Q –II Q(a) (b) ch25.indd   11 12/20/07   1:39:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 FIGURE 22.2  Small boat radar ( Courtesy Furuno USA, Inc. ) ch22.indd   3 12/17/07   3:02:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
  00 0.! ASS HF  WHERE   
 16.28 Maximum improvement factor as a function of a fractional envelope shift for typ- ical pulse envelope shapes. Subscript 1 indicates single delay; 2, double delay. Pulse shape a = rectangular; b = cosine; c = cosine-squared; d = triangular; e = gaussian. 
 BISTATIC RADAR  23.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 Hitchhikers using cooperative monostatic radar transmitters also have the inher - ent capability to counter retro-directive jammers operating against their host radar.  Because the jammer uses a high-gain antenna to retro-direct the transmitter’s signal  back to the transmitter (and thus its monostatic receiver), the spatially separated hitch - hiker can be positioned in the sidelobes of that antenna, thus reducing the effectiveness  of the jammer. A rule of thumb is to anticipate enhanced hitchhiker performance when - ever the bistatic angle is greater than the estimated 3-dB width of the retro-directed  main beam. 
 The design limitation onthe volume ofspace that can becovered frequently enough tobeuseful isleast troublesome inthecase ofaradar equipment designed todeal ~rith surface targets. Inthis case, one is interested only incoverage ofaplane, not insearching the volume of space that may contain aircraft. The most advanced equipment ofthe rapid-scan precision-tracking type that was infield use atthe end of World War IIwas the AN’/TPG-l, which had been designed forthe control ofshore-battery fireagainst ships. 
 DETIC MISSION AND EXACT 
 BEAM INTERFERENCES DEPENDS ON THE AVAILABLE NUMBER OF HIGH GAIN BEAMS ! SO 
 ENCE LOSSES  TO BOTH THE ELECTRIC %  OR MAGNETIC (  FIELDS 4HIS CAUSES ATTENUATION OF THE ORIGINAL ELECTROMAGNETIC WAVE 0LANE WAVES ARE GOOD APPROXIMATIONS TO REAL WAVES IN MANY PRACTICAL SITUATIONS -ORE COMPLICATED ELECTROMAGNETIC WAVEFRONTS CAN BE CONSIDERED AS A SUPERIMPOSITION OF PLANE WAVES  AND THIS METHOD MAY BE USED TO GAIN AN INSIGHT INTO MORE COMPLEX SITUATIONS &OR MOST SOILS OF INTEREST IN '02  THE MAGNETIC RESPONSE IS WEAK AND NEED NOT BE CONSIDERED AS A COMPLEX QUANTITY  UNLIKE THE PERMITTIVITY AND CONDUCTIVITY (OWEVER  IN CERTAIN SOIL TYPES  SUCH AS THOSE DERIVED FROM VOLCANIC ROCKS OR OTHERWISE HIGH IN IRON CONTENT  FULL CONSIDERATION OF THE MAG 
 LIMITED DETECTION  THIS CAN BE COMPENSATED BY A REDUCTION IN DWELL TIME  BUT FOR CLUTTER 
 1354. 1355.  Scptcmbcr, 1975. 
 NIFICANT AS THIS MAY CAUSE MODIFICATION OF THE ANTENNA RADIATION CHARACTERISTICS BOTH SPATIALLY AND TEMPORALLY AND SHOULD ALSO BE TAKEN INTO ACCOUNT IN THE SYSTEM DESIGN )N THE CASE OF AN ANTENNA PLACED ON AN INTERFACE  THE TWO MOST IMPORTANT PARAMETERS ARE THE CURRENT DISTRIBUTION AND THE RADIATION PATTERN !T THE INTERFACE  CURRENTS ON THE ANTENNA PROPAGATE AT A VELOCITY  WHICH IS INTERMEDIATE BETWEEN THAT IN FREE SPACE AND THAT IN THE DIELECTRIC )N GENERAL  THE VELOCITY IS RETARDED BY THE    ER  4HE NET  RESULT IS THAT EVANESCENT WAVES ARE EXCITED IN AIR  WHEREAS IN THE DIELECTRIC THE ENERGY IS CONCENTRATED AND PREFERENTIALLY INDUCED BY A FACTOR OF N  4HE RESPECTIVE CALCULATED FAR 
 even though the feed appears to be op- posite the reflector. The ASR-9 (Fig. 6.14) typifies shaped reflector antennas designed by these procedures. 
 7ESLEY 0UBLISHING #OMPANY    3EC   " 3PAULDING  $ (ORTON  AND 0 (UONG  h7IND !SPECT &ACTOR IN 3EA #LUTTER -ODELING v PRESENTED  AT  )%%% )NTERNATIONAL 2ADAR #ONFERENCE    " , ,EWIS AND ) $ /LIN  h%XPERIMENTAL STUDY AND THEORETICAL MODEL OF HIGH 
 ,\Ê 
 12,Sec.49.. 26 THERADAR EQUATION [SEC. 2.5 small except forsmall values ofO,and since Gvanishes forvalues ofo outside theinterval 00to~/2, itispermissible towrite and evaluate the integral asfollows; ()7raij 1G, H=/2 - sin2 —i 4UCSCZ 00~. 
 This system isuseful only when theinterrogator is expected tolook atthe beacon steadily. Avariant that has been sug- gested foruse with scanning radars isarapid code ofthis kind which would break thereply arconthePPI into dots and dashes. Only simple codes could beused because ofthe limitation ofbeamwidth and the complete uncertainty astothe part ofthe coding cycle forwhich the broken reply arcwould becentered. 
  &)'52%    -(Z TONE SAMPLED AT A   -(Z  r )&  AND B   -(Z  r )&        . 
 MENT SO THAT THE PHASING AT THE MNTH ELEMENT IS GIVEN BY  YMN XS YS  M4 N4   WHERE 4XS   OK DX COS @XS   ELEMENT 
 Timmoneri, and A. Farina, “Phased-array radar systems in support of the  Medium Extended Air Defense System (MEADS),” IEEE Int. Symp. 
 The other parameters of simulations are given in Table 7. The simulated SAR images under different wind speeds are shown in Figure 16. ȱ (a)ȱ (b)ȱ (c)ȱ Figure 16. 
 In this paper, convolutional neural networks (CNNs) are applied to ship classiﬁcation by using SAR images with the small datasets. To solve the problem of over-ﬁtting which often appeared in training small dataset, we proposed a new method of data augmentation and combined it with transfer learning. Based on experiments and tests, the performance is evaluated. 
 24Range Resolution • Two targets are resolved if their returns do not overlap.  The range  resolution corresponding to a pulse width τ is                                      . ∆R=R2−R1=cτ/2 cτ/2 cτcτ/2 TIME STEP 1 TIME STEP 2 TIME STEP 3 TIME STEP 4to to+τ/2 to+τ to+3τ/2R1 R2R1 R1R1R2 R2 R2TARGET. 
 DETECTOR CIRCUIT IS ADJUSTED WITH A  PHASE SHIFT ON ONE CHANNEL TO GIVE ZERO OUTPUT WHEN THE TARGET IS ON AXIS AND AN OUTPUT INCREASING WITH INCREASING ANGULAR DISPLACEMENT OF THE TARGET WITH A POLARITY CORRESPONDING TO THE DIRECTION OF ERROR 4YPICAL FLAT 
 VIDE THE WIDE INSTANTANEOUS BANDWIDTH TO ALLOW  FOR EXAMPLE  USE OF WIDEBAND NARROW PULSES TO PROVIDE THE RANGE RESOLUTION REQUIREMENTS FOR TRACKING RADAR APPLICATIONS 4WO 
 LOOK (273 #ONFIRM  THE PROBABILITY OF FALSE ALARM PER RANGE 
 1448–1461, November 1974. 36. J. 
 Zahm, C. L.: Application of Adaptive Arrays to Suppress Strong Jammers in the Presence of Weak  Signals, IEEE Trans., vol. AES-9, pp. 
 CONTROL RADARS 4HE TWO 
 This isthefundamental quantity studied intests. The radar equation given asEq. (2.M), R d4pnL4 ?f, ~,x. 
 Their chief limitations areinthe allowable pulse repetition frequency (about 2000 DDS maximum) and inobtainable precision ofpulse timing. This type .. coup \! -1Triggerinput *IIofswitch can handle several mega- watts, and should beuseful inappli- cations that donot require great flexibility oraccuracy offiring. 
 Rept. FP8-T-013, November 1975. 21. 
 &EED 3YSTEMS  0HASED ARRAYS MAY BE IN THE FORM OF LENS ARRAYS OR REFLEC 
 Figure 17.15 illustrates a common method of spacing the gates for the general case where the gate spac- ing T5, the gate width T^, and the transmitted pulse T, are all unequal. Selecting T^ > ts reduces the range-gate straddle loss but increases the possibility of range ghosts. Selecting T, = T8 maximizes range performance.TRANSMITTEDPULSES(PRFNO 1) RECEIVEDPULSES(PRFNO. 
 The active element in each final transmitter stage can be either a tra - ditional vacuum tube62 or a solid-state device.63,64 Most operational HF radars employ  solid-state amplifiers based on a hierarchy of modules, starting with elemental ampli - fiers of perhaps 500 W and combining these progressively via passive networks until  the final output power is attained. Relative phase shifts or time delays are inserted in  the amplifier chain, driving each antenna element to steer the resultant beam. This  architecture enhances reliability and provides graceful degradation in the event of  module failure. 
 Practitioners in the field of radar meteorology often use Ze and Z interchangeably, albeit incorrectly. Finally, it is important to note the range of Z values that are of meteorological significance. In nonprecipitating clouds, Z values as small as —40 dBZ are of in- terest. 
 In contrast to the pattern of a flat plate, the RCS pattern of a corner reflector is quite broad. This is true because the corner reflector is a reentrant structure, and no matter what its orientation (within limits, of course), internally reflected waves are directed back toward the source of the incident wave. A corner reflec- tor is formed by two or three flat plates intersecting at right angles, and waves impinging on the first face are reflected onto the second; if there is a third face, it receives waves reflected by the first two faces. 
 There aretwo reasons formak- ingthetuning automatic. The first isthat astheantenna scans, va@- tions instanding-wave ratio arising from asymmetrical rotary joints or reflections from near-b yobjects can pull the magnetron several mega- cycles persecond. Manual tuning issoslow relative toscanning that it brings inonly part ofthe picture atatime. 
 F. H. Dyer. 
 RANGE SURVEILLANCE  COM 
 SWATH ALLOCATION BURDEN FALLS ONTO THE ANTENNA 3CAN3!2 REQUIRES RAPID ELEVATION BEAM STEERING  SUCH AS THROUGH A PHASED ARRAY EG  4ERRA3!2 
 ELECTRONIC NAVIGATION 153  first trial bombing raid was made on the Ruhr by  Mosquitoes flying at 28,000 feet on a wild winter's  night. The aircraft were navigated to some point on the  circular track about 50 miles from the target by Gee.  Oboe control then took over, and the pilot was given  signals to guide him along the curved track. 
 3.2a. The transmitkr  generates a continuous (unmodulated) oscillation of frequency .fo, which is radiated hy the  antenna. A portion of the radiated energy is intercepted by the target and is scattered, some of  it in the direction of the radar, where it is collected by the receiving antenna. 
 M. Headrick: Estimating the Scattering Coefficient of the Ocean Surface for High-Frequency Over-the-Horizon Radar, Naval Res. Lab. 
 The following considerations will berestricted tocases where the indi- vidual target issufficiently small, compared with the distance from the transmitter, topermit theincident electromagnetic field atthetarget to beapproximated byaplane wave propagating inthe direction ofthe target away from the transmitter; this ischosen asthe zdirection. The problem offinding the cross section then reduces tothe mathe- matical problem offinding that solution ofMaxwell’s equations which atlarge distances from the target reduces tothe incident plane wave and atthetarget fulfills theproper boundary conditions. Suppose asolution ofthis problem hasbeen found. 
 I · .. j,  REFERENCES  1. Ridenour, L. 
 %LECTRONICS 'MB(  .   #)6), -!2).% 2!$!2   ÓÓ°Î 3HIPBORNE RADAR HAS HAD A REMARKABLY LONG HISTORY )TS CONCEPTION IN THE PERIOD FROM   TO  WAS REMARKABLY PROPHETIC AND STILL REVERBERATES INTO THE PRESENT CENTURY &OR THIS REASON  A SHORT !PPENDIX TO THIS CHAPTER OUTLINES THE  EARLY STEPS IN THE EVOLU 
 STATE TECHNOLOGY BECAUSE TRANSIS 
 Neuf, D.: Radar Retrofit: Increase Receiver Sensitivity Cost EITectively, Microwave System News, vol.  5, pp. 55-60, April/May, 1976. 
 RATIO hBILLBOARDv  STYLE PIONEERED BY 3EASAT #OURTESY OF )!)  )SRAEL  . £n°£{  2!$!2 (!.$"//+  ANTENNAS SUGGESTS THAT THE DOMINANT OBJECTIVE IS FINE RESOLUTION  WHICH NECESSITATES A  RELATIVELY NARROW RANGE SWATH 0UBLISHED SPECIFICATIONS NOTE THAT THE INTENDED RESO 
 WHILE 
 STATE PHASED ARRAY ANTENNA USES INDIVIDUAL TRANSMITRECEIVE 42  MODULES WITH INTERNAL PHASE SHIFT CAPABILITY %ACH 42 MODULE  IS LOCATED BEHIND AN ASSOCIATED RADIATING ELEMENT IN A TWO 
 17, pp. 25–27,  January 1974. ch08.indd   41 12/20/07   12:52:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Also,  some moving targets such as aircraft nying in formation can look like extended targets.)  Successive A-scope sweeps (pulse-repetition intervals) are shown in Fig. 4.3b toe. Echoes from  fixed targets remain constant thrnughout, but echoes from moving targets vary in amplitude  from sweep to sweep at a rate corresponding to the doppler frequency. 
 464–468. 25. G. 
 However, thismaynotalwaysbetrue.Propeller-driven aircraftproduce modulation components atthebladefrequency andharmonics thereofandcancauseasub­ stantialincrease inthespectral energydensityatcertainfrequencies. Ithasbeenfoundexper­ imentally thatthetracking accuracy ofradarsoperating withpulserepetition frequencies from 1000to4000Hzandalobingorscanrateone-quarter oftheprfarenotlimitedbyecho amplitude f1uctuations.29 Thepercentage modulation oftheechosignalduetocross-section amplitude lluctuations isindependent ofrangeifAGCisused.Consequently, theangularerrorasarcsultofampli­ tudefluctuations willalsobeindependent ofrange. Anglefluctuations.29.3oChanges inthetargetaspectwithrespecttothcradarcancalisethc apparent centerofradarreflections towanderfromonepointtoanother. 
 ORDER PRODUCTS MAY CAUSE PROBLEMS . 
  5(&  (IGH !2# 
 1597–1609, May 2005. 131. D. 
  IS AT 3 
 The results of the second experiment are summarized in Table 6. 305. Sensors 2019 ,19,6 3 T able 6. 
 DC POWER CONDITIONERS o TO HARMONICS OF THE 02&  $ESIGN THE SYSTEM TO BE FULLY COHERENTp  0ROVIDE )& ,IMITERS PRIOR TO !$ CONVERTERS "E WARY OF VIBRATION AND ACOUSTIC NOISE 4HE FACTS ARE AS FOLLOWS  4HE BASIC -4) CONCEPT DOES NOT REQUIRE A LONG TIME ON TARGET TO RESOLVE TARGETS FROM  FIXED CLUTTER )NSTEAD  -4) SYSTEMS REJECT FIXED CLUTTER THROUGH A SUBTRACTION PROCESS  WHILE RETAINING MOVING TARGETS  4RANSMITTER INTRAPULSE ANOMALIES HAVE NO AFFECT ON -4) PERFORMANCE IF THEY REPEAT  PRECISELY PULSE 
  
 The clutter-to-noise ratio was selected to limit performance to 92 dB. The improvement factor for adaptive arrays is usually defined as the ratio of the signal-to-interference-power ratio at the output of the processor to the signal- to-interference ratio at the input of the processor. The signal is specified as com- ing from the direction and at the doppler frequency specified by the quiescent weights. 
 TUDE WHEN P      AND SIMPLIFYING GIVE   %S A C O S S I NPP § ©¨¶ ¸·PL    4HE ABSOLUTE VALUE OF  %A P    IS PLOTTED IN &IGURE  AS A FUNCTION OF  O SK  SIN P   )F THE PLOT HAD BEEN IN TERMS OF THE ANGLE  P  THE LOBES WOULD HAVE BEEN FOUND TO   INCREASE IN WIDTH AS \ P  \ INCREASED 4HE MAIN BEAM OCCURS WHEN SIN  P     4HE OTHER  LOBES HAVE THE SAME AMPLITUDE AS THE MAIN BEAM AND ARE REFERRED TO AS  GRATING LOBES &)'52%  2ADIATION PATTERN OF TWO ISOTROPIC RADIATORS .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°££ 4HEY OCCUR AT ANGLES GIVEN BY SIN  P   o ;MSK =  WHERE  M IS AN INTEGER &OR THE HALF  SPACE GIVEN BY  
 Gatingthealtitude returnhasthedisadvantage thattargetsatrangescorresponding totheaircraftaltitude willalsobeeliminated fromthe receiver. Another method ofsuppressing thealtitude returninthepulseradaristo eliminate thesignalinthefrequency domain, ratherthaninthetimedomain, byinserting a rejection filteratthefrequency fa.·Thesamerejection filterwillalsosuppress thetransmitter­ to-receiver leakage. Theclutterenergyfromthemainbeammayalsobesuppressed bya rejection filter,butsincethedoppler frequency ofthiscluttercomponent isnotfixed,the rejection filtermustbetunableandservo-controlled totrackthemain-beam clutterasit changes becauseofscanning orbecauseofchanges inaircraftvelocity. 
 Kelleher, and H. H. Hibbs: An Organ Pipe Scanner, IRE Trans., no. 
 Conformal schemes and adaptation  to satellites, aircraft and other platf orms are more readily realizable.   14.2 The Receiver Subsystem   The receivers of software defined Radar sensors have similar configurations and stru ctures to that  of the transmitters. Both may use the same antenna. 
 AES-8, pp. 743-750, November, 1972.  42. 
 The number of 1Failure toappreciate thepower oftheobserver tointegrate wasresponsible for some disappointment with early electrical integrating devices, which, through no fault oftheir own, didnotbring theexpected improvement over thesimple A-scope.. 42 THERADAR EQUATION [SEC.2.11 sweeps integrated then islimited bythe number ofpulses striking the target during the scan and not bythe screen persistence. If,however, thelatter issolong that storage iseffective from one scan tothenext, we FIG.2.7.—In thisseries ofphotographs, thenumber ofA-scope sweeps recorded during each exposure wasvaried from 12to400. 
 There are digital devices that provide the interface between the system computer and the  radar equipment, digital and analog signal processors, monitoring and controls, and eqiiip-  ment for space object identification. The programs for the computer total over 1,250,000 words  of storage. About 60 percent of this large number of worils consists oftlecis~o~l tiiblcs to locittc  fa~llts when compared to expected outputs. 
 (ILL "OOK #OMPANY    P   53 !IR &ORCE WEB SITE  $ECEMBER   HTTPWWWWRSAFRLAFMILOTHERMMFCOMPRESHTM - ) 3KOLNIK   )NTRODUCTION TO 2ADAR 3YSTEMS   .EW 9ORK -C'RAW 
 A small sample of the transmitted signal is passed through a vari - able attenuator and a variable phase shifter and combined with the received signal. The  amplitude and phase of the signal sample are then adjusted so as to cancel the signal  received in the absence of the target. The availability of low-cost, phase-locked, frequency-synthesized sources now  makes it attractive to collect wideband RCS data, which contain far more target- scattering information than CW measurements made at single frequencies. 
 DIRECTION 
 Pulse  width = 20 ns. beamwidth = 0.5". grazing angle = 4.7". 
 The transmitter is fed into one end of  the waveguide feed whose slots are designed to produce a number of contiguous beams in  elevation with amplitudes controlled so a~ to produce a cosecant-squared radiation pattern.  On reception, a receiver is inserted at each end of the feed. The echo signal from a particular  direction isfreceived at one of the slots and is divided in the waveguide feed. 
 FILLED INTERIOR IS USUALLY EMPLOYED TO ENSURE LONG 
 In cases where an insufficient doppler shift occurs, such as with a stationary or  tangential target, range resolution is the chief means for seeing a target in clutter.  FIGURE   8. 25 Comparison of ambiguity functions for N = 10 stepped linear and Costas sequence showing  the impact of frequency order40 Stepped Linear F requency Code Frequency Inde xSequence Index Frequency Inde xSequence IndexCostas Code 000 0−11 1 1−1 −1−1f/B f/Bt/tp t/tp ch08.indd   26 12/20/07   12:50:42 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 TIONARY BEHAVIOR  BISTATIC CLUTTER SUPPRESSION HAS BEEN GREATLY IMPROVED  AS REPORTED BY 7 -ELVIN IN #HAPTER  OF 7ILLIS AND 'RIFFITHS  ÓÎ°ÈÊ /, 
 The target has a velocity vector of magnitude V and aspect  angle d  referenced to the bistatic bisector. The transmitter and receiver have velocity  vectors of magnitude VT and VR and aspect angles d T and d R, respectively, referenced  to the north coordinate system of Figure 23.1. All vectors are projections of the three- dimension vectors onto the bistatic plane. 
 l'l'.White.W.D.:PatternLimitations inMultiple-Beam Antennas, IRETraIlS..vol.AP-IO,pp.430436. July,1962. X9.Moody, H.1.:TheSystematic DesignoftheButlerMatrix,IEEETrailS.,vol.ApolI.pp.7H6..7HH. 
 P. Roesli: Use of Doppler Radar and Radar Networks in Mesoscale Analysis and Forecasting, ESA J., vol. 9, pp. 
 Itissomctimw neceswr~” toadd dissimilar deflections inthe s~me ,lirection. ll-henc~-er practiralj this i+done by achling the ~-ariou~ deflecting currents inthe same coil. Tn some cases. 
 The limitations of lower beam voltage, however, can be overcome by separating  the single electron beam into a number of smaller beams, called beamlets,  so that each  of the beamlets has a low enough current density to avoid the undesirable repulsive  effects of a high current-density beam. According to Nusinovich et al.,9 each beamlet  is transported down its own individual drift channel (a metallic-walled tube), parallel  to, but isolated from, the other beamlets. They are allowed to interact only over the  small axial extent of the cavity gap. 
 33, no. 1,   pp. 102−115, January 1997. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar.  METEOROLOGICAL RADAR  19.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 provide a shared infrastructure for the CASA radars. 
 TUNED KLYSTRON AND THE CLUSTERED 
 J. Fleming, “The Navy space surveillance system,” Proc. IRE , vol. 
 TR cPRIT C kPRIT CAc p kA jA= × +   =+ ×=+22 21 2τ, ,× × + =j TP f rC rV f PRIj k j kδ or blind or ( ,) [ mod( , /3 41j j k j R r PRI )] [mod(, ) ] ×blind or (5.1) where: Rc is maximum desig n clear range c is the velocity of light 2.9979 ⋅ 108 m/s t p is transmitted pulse width, k and j are indices e.g. 0 …4 C1 is an odd integer e.g. 9, C2 is an even integer e.g. 
 LIMITED FOOTPRINT ABOUT  SMALLER THAN USUAL . 
 TION OF A RADAR GENERALLY HAS TO EMPLOY A RADAR EQUATION TAILORED TO THAT SPECIFIC APPLICA 
   AND  !POLLO n -ARS BISTATIC RADAR MEASUREMENTS  WERE MADE USING  -ARINER 
 IEEE Sens. J. 2019 ,19, 3784–3796. 
 In this case, when strong land clutter is a problem, a good MT{ or pulse-doppler  radar is required. MTI or pulse-doppler radar is also necessary in radar carried by high-nying  aircraft that must detect other aircraft masked by sea clutter.  Although ships arc moving targets that might be candidates for MTI radar, it is not often  that MTI is needed for this application. 
 E.: Path-length Microwave Lenses, Proc. IRE, vol. 37, pp. 
 Skillman, W. A., and D. H. 
 D. R. Rhodes, Introduction to Monopulse , New York: McGraw-Hill Book Company, 1959. 
 Although the official ITU description of millimeter waves is from 30 to 300  GHz, in reality, the technology of radars at Ka band * is much closer to the technology  of microwave frequencies than to the technology of W band. The millimeter wave radar  frequencies are often considered by those who work in this field to have a lower bound  of 40 GHz rather than the “legal” lower bound of 30 GHz in recognition of the significant  difference in technology and applications that is characteristic of millimeter wave radar.  Microwaves  have not been defined in this standard, but this term generally applies to  radars that operate from UHF to Ka band. 
 C., and C. A. Whitmer: "Crystal Rectifiers," MIT Radiation Laboratory Series, vol. 
 CENTIMETRIC TECHNIQUE i21  tube is the ‘drift’ space, and the second passage of the  electron stream through from inner to outer concentric  feeder is through the catcher space. Heil tubes can be  used to give an output of some 4 watt, but again the  efficiency is very low, usually not more than 5 per cent.  Although tubes of the klystron type handle such low  power that they cannot be used as oscillators for micro-  wave radar transmitters, they can be used for the equally  important purpose of acting as local oscillators in the  receiving end of the chain. 
 L. C. and J. 
 For example, stalo phase modulation caused by power supply ripple at 120 Hz creates nearly equivalent phase modulation of a clutter echo from nearly 100-nmi range (delay of 1200 JJLS resulting in O dB range factor). Phase modulation of a clutter echo with a range delay of 15 JJLS is about 38 dB less than the stalo phase modulation because the stalo phase has changed only slightly in this short time interval; the phase added by the stalo to the transmitted pulse is nearly the same as the phase subtracted from the received echo in the mixer. Adding the decibel values of the measured stalo spectrum and the range- dependent effect at each modulation frequency provides the spectrum of undes- ired doppler modulation at the output of the mixer. 
 7. 7 X 3.85 [!t.e::- . \0 \"' ~ ,•~I o'f. 
 The normal solution to that problem is to use an FM-CW system, in which the transmitted frequency is swept (usually linearly ver- sus time) so that both range and doppler information can be extracted by proper in- terpretation of the received signals; the frequency of the echo determines how long ago the signal was transmitted and thus the range to the target. Nevertheless, one fundamental limitation in such CW radars is that weak echoes from distant targets must compete with strong echoes from short-range clutter. This requires superb clut- ter cancellation, which in turn is limited by transmitter instabilities (which produce noise sidebands). 
 10.7] PULSER CIRCUITS 361 cen~ ofthepulser power output, but itruns ashigh as10percent insome high-power pulsers. The output pulse shape isusually more nearly rectangular from ahard-tube than from aline-type pulser. Except for special cases, hard-tube pulsers arealmost always built fordirect output, and thus avoid the inductance and capacity added bythe impedance- matching pulse transformer between the line-type pulser and the load, with theresulting oscillations inthe pulse shape. 
 A.: Utilization of the E-3A Radar in Europe, Proc. Mil. Electron. 
 02) DELAYED BEAMS 4HESE BEAMS ARE  IN TURN  ADDED TOGETHER TO FORM THE FINAL 34!0 WEIGHTED DETECTION BEAM ! SIMPLISTIC VIEW OF HOW THESE THREE BEAMS PERFORM MOTION COMPENSATION IS ILLUS 
 The filter has to be retuned if the mixer must operate at another  frequency. Also, the high Q of the filter introduces a loss which will increase the system  noise-figure.  A method for achieving a reactive termination without narrow-bandwidth components is  the irrrage-recovery mixer shown in Fig. 
 Therefore, targets are divided into two categories according to their scattering characteristic across azimuth: isotropic targets and anisotropic targets. In conventional SAR working modes, such as strip-map mode and spotlight mode, targets are assumed isotropic because the view angle is small. However, scattering variation cannot be ignored in some new SAR workingmodes. 
 3. The frequency of the direct and the scattered signals. These will be different if the target is in  motion (dopplcr effect). 
 DISTRIBUTED PROCESS  THE BASIC CLUTTER  PARAMETER IS TAKEN TO BE THE NORMALIZED RADAR CROSS SECTION .2#3    R     OF THE SURFACE   COMMONLY REFERRED TO AS  SIGMA ZERO AND EXPRESSED IN DECIBELS  RELATIVE TO  MM )T IS  OBTAINED EXPERIMENTALLY BY DIVIDING THE MEASURED RADAR CROSS SECTION OF AN ILLUMINATED PATCH OF THE SURFACE BY A NORMALIZING AREA  SO DIFFERENCES IN THE DEFINITION OF THIS AREA CAN LEAD TO INCONSISTENCIES AMONG VARIOUS REPORTS OF .2#3 MEASUREMENTS 3CATTERING FROM ANY DISTRIBUTED TARGET INVOLVES THE PRODUCT OF THE TRANSMITTING AND RECEIVING SYS 
 N. C Currie. and M. 
 13.15a); and (b)“scale-of-two” circuits, inwhich successive triggers from asingle source induce alternate transitions between two stable stqtes (Fig. 13”15b). The name “scale-of-two” arises from thefact that ifsharp pulses are derived from those wavefronts ofo~epolarity their number will be half that oftheoriginal trigger pulses. 
 ANCE USUALLY CONSISTS OF ASSESSING THE MISSILE PERFORMANCE  MEASUREMENT OF THE TARGET  AND MISSILE LOCATION  PREDICTION OF THE PATH OF EACH  AND UPDATING THE RESULTING DATA TO THE MISSILE FOR THE BEST FUTURE INTERCEPT OF THE TARGET )T MAY ALSO INCLUDE THE MOST CURRENT ESTIMATE OF THE TARGET TYPE AND ATTITUDE FOR BEST FUZING 4HE MISSILE USUALLY SENDS DATA ABOUT ITS STATE OF HEALTH  OWNSHIP MEASUREMENTS  REMAINING FUEL AMOUNTS  AND TARGET ACQUISITION  IF ANY  7HEN THE MISSILE IS CLOSE TO THE DATA LINK AIRCRAFT WHICH MAY OR MAY  NOT BE THE LAUNCHING PLATFORM   COMMUNICATION IS OFTEN THROUGH AN APERTURE OTHER THAN IN THE MAIN -&!2 !S THE DISTANCE GETS GREATER  THE PRIMARY -&!2 APERTURE IS USED !S THE DATA LINK AIRCRAFT MANEUVERS  THE APERTURE THAT HAS THE LARGEST PROJECTED AREA IN THE DIREC 
 NOISE RATIO  AS SHOWN IN &IGURE  .OTE THAT THESE VALUES ONLY RELATE TO THE RECEIVER NOISE AND DO NOT INCLUDE EXTERNAL SOURCES OF FALSE ALARMS DUE TO CLUTTER 4HE MOST BASIC MODEL IS THAT OF THE TRANSMISSION LINE EQUIVALENT AND IS USEFUL FOR  ASSESSING THE TIME 
 RECEIVER  PROPAGATION TIME  CONVERTED TO A TRANSMITTER 
 Graf. G.: On the Optimization of the Aspect Angle Windows for the Doppler Analysis of the Radar  Return of Rotating Targets, IEEE Trans., vol. AP-24, pp. 
 ONSTRATIONS OVER PRESELECTED hSUPERSITESv AND   FIVE 
 2ESOLUTION /CEAN 4OPOGRAPHY 3CIENCE 7ORKING 'ROUP -EETING   $ #HELTON ED   #ORVALLIS   /REGON /REGON 3TATE 5NIVERSITY    2 3CHARROO AND 0 6ISSER  h0RECISE ORBIT DETERMINATION AND GRAVITY FIELD IMPROVEMENT FOR THE %23  SATELLITES v * OF 'EOPHYSICAL 2ESEARCH  VOL   PP n    ! 2 :IEGER  $ 7 (ANCOCK  ' 3 (AYNE  AND # , 0URDY  h.!3! RADAR ALTIMETER FOR THE  4/0%80OSEIDON PROJECT v 0ROCEEDINGS OF THE )%%%  VOL   PP n  *UNE   0 # -ARTH  * 2 *ENSEN  # # +ILGUS  * ! 0ERSCHY  * , -AC!RTHUR  $ 7 (ANCOCK    ' 3 (AYNE  # , 0URDY  , # 2OSSI  AND # * +OBLINSKY  h0RELAUNCH PERFORMANCE OF THE .!3! ALTIMETER FOR THE 4/0%80OSEIDON 0ROJECT v  )%%% 4RANSACTIONS ON 'EOSCIENCE AND 2EMOTE  3ENSING  VOL   PP n    $ " #HELTON  % * 7ALSH  AND * , -AC!RTHUR  h0ULSE COMPRESSION AND SEA 
 each of unity a~nplitude but with phase difference $, is  [2(1 + cos I/I)]"~. 'i'tlerefore tlle ratio of the power incident on the target at B to that which  would be incident if tlie target were located in free space is  4n/la 11, 2~/1,h, 1 - cos ------ = 4 sin2 - AR AR  Because of reciprocity, the path from target to radar is the same as from radar to target. The  power ratio at the radar is therefore  21c1ta1r, q4 = 16 sin --- AF!  The radar equation describing the received echo power must be modified by the propagation  factor q4 of Eq. 
 RADAR REQUIREMENTS OF n  ANGLE 
 A separate receiver is  required for each of the simultaneous beams.  I)_1<! __ eleY9~1+ae-y--ofstngk~-scauoLn.&_bea!:n JD radars i~usually less than that  of other systems. This is due to the relatively_Jew pulses (sometimes only one pulse) per-heam  -·•·•··~ •" •.• ,,,m ,,, ,,,, •••  IlQfil.!_i_Q_n_,_as well as the error introduced by the_J.?rgct echo ampJjtude lluct when  sequential rather than simultaneous angle measurements are made. 
 Inthissection thetheoretical accuracies ofradarmeasurements willbederived. To simplify theanalysis. itisassumed thatthesignalislargecompared withthenoise.Thisisa reasonable assumption sincethesignal-to-noise ratiomustberelatively largeifthedetection decision istobereliable(Sec.2.5).Furthermore, aswillbeevident later,largesignal-to-noise ratiosarenecessary foraccurate measurements. 
 FIG. 18.6 Conical-scan-radar antenna beam 3 dB contour (solid circle) and path of rotation (dashed circle) of the beam center. NORMALIZED OFFSETANGLE /3(BEAMWIDTHS) FIG. 
 ulde ~\  Input Output  L~river terminals fixture b'igure 8.13 Dual-modr rrci-  procal phase sllifrcr configura-  tion. (t'rottr i 111111  l'o~rrlg. I"')  of merit. 
 Thelossesindecibels per100ftforradar transmission linesareshowninFig.2.28.Atthelowerradarfrequencies thetransmission line introduces littleloss,unlessitslengthisexceptionally long.Atthehigherradarfrequencies, attenuation maynotalwaysbesmallandmayhavetobetakenintoaccount. Inaddition tothe losscsinthetransmission lincitself,anadditional losscanoccurateachconnection orbendin thelineandattheantenna rotaryjointifused.Connector lossesareusuallysmall,butifthe connection ispoorlymade,itcancontribute significant attenuation. Sincethesametransmis­ sionlineisgenerally usedforbothreceiving andtransmission, thelosstobeinserted inthe radarequation istwicetheone-way loss. 
 Total effective increases in gate width can be achieved by paralleling several adjacent gates in order to in- crease the total channel area per given area. This is similar to increasing emit- ter periphery per unit base area in the design of bipolar transistors. In addi- tion, the structure must be designed to maintain as high a source-drain breakdown voltage as is possible in order to maximize power output capabil- ity. 
 Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar.  PULSE DOPPLER RADAR  4.436x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 Eq. 4.17 assumes an unmodulated, rectangular transmit pulse shape with the receive  gate matched to the transmit pulse width. 
 The fact that most  practical radars employ this type of waveform attests to its usefulness far better than any  theoretical analysis which might be presented here. It is encouraging, however, when theoreti­ cal considerations substantiate the qualitative, intuitive reasoning upon which most practicc1l  engineering decisions must usually be based, for lack of any better criterion.  ('  Single frequency-modulated pulse. 
 TATION FIELDS 3MALL  HIGHLY MOBILE RESEARCH RADARS PROVIDE MANY OF THE SAME CAPABILITIES AS THE FIXED RADARS  $UAL POLARIZATION TECHNIQUES  ARE USED FOR IMPROVED QUANTITATIVE #HAPTER    4HE .ATIONAL #ENTER FOR !TMOSPHERIC 2ESEARCH IS SPONSORED BY THE .ATIONAL 3CIENCE &OUNDATION. £°Ó  2!$!2 (!.$"//+  PRECIPITATION MEASUREMENT  FOR DETECTING HAIL  AND FOR DISCRIMINATING ICE PARTICLES SNOW   FROM WATER RAIN  &URTHERMORE  GROUND 
 (9.1)] the output noise No of  the two circuits iri cascade is  No = FOG', G2k71;,B, = noise from network 1 at output of network 2  + noise ANz introduced by network 2 (9.h)  The contribution of the second network to the overall noise-figure may be made negligible if  the gain of the first network is large. This is of importance in the design of multistage receivers.  It is not sufficient that only the first stage of a low-noise receiver have a small noise figure. 
 I. Skolnik (ed.),  McGraw-Hill Book Co., New York, 1970, sec. 1 l.9. 
 MATOR  WHERE  2   $    4HE DESIRED PASSBAND IS THE LIGHTLY SHADED AREA CENTERED AT    (Z WITH BANDWIDTH  "7 4HE DARKER SHADED AREAS WITH BANDWIDTH  "7 IN &IGURE  A  INDICATE SIGNALS THAT WILL ALIAS INTO THE BASEBAND SIGNAL AFTER DECIMATION BY   AS SHOWN IN &IGURE  B AFTER ,YONS   .OTE THAT UNLESS  "7 IS VERY SMALL  A SIGNIFICANT PORTION  OF OUT 
 As previously discussed, the performance of these radars in operational use was hugely variable. Variations in sensitivity of tens of dB between radars and over time were noted by TRE and CCDU [ 4,5]. This was due to the dif ﬁculty in correctly tuning and maintaining this new type of equipment, but also due to the very variable nature of the maritime environment, which always makes comparative performance assessments dif ﬁcult [ 6]. 
 (2.55) was derived for a rectangular pulse, it can be applied to other waveforms  as well, provided matched-filter detection is employed. Most calculations for probability of  detection with signal-to-noise ratio as the parameter apply equally well when the ratio of  signal-energy lo noise-power-per-hertz is used instead. The radar equation developed in this  chapter for pulse radar can be readily modified to accommodate CW, FM-CW, pulse-doppler,  MTI. 
 Ellerbruch, “Development and testing of a microwave system to measure coal  layer thickness up to 25 cm,” Nat. Bur. Stds., Report No.SR-723-8-79 (Boulder, CO), 1979. 
 34 in Skolnik, M. I. (ed.): "Radar Handbook," McGraw-Hill Book Company, New York, 1970. 
 But in  the receiver itself the process is not continuous. In many  of the circuits we must arrange not for steady voltage  changes, such as those of speech frequency in a radio  low-frequency amplifier, but for spasmodic, sudden,  staccato changes. We need such bursts of energy, for  instance, in saw-tooth form to provide the common  form of linear time-base in basic radar equipment. 
 AVERAGING #&!2 PR OCESSORS IN MULTIPLE 
 11.5] D,C”PLEXING AND TR SWITCHES 407 tions atlow frequencies. The essential reason forthis isthat such low-- frequency circuits donotprovide acorrespondingly large volume forthe storage ofenergy. Tomake acavity useful itisnecessary toprovide some means of introducing and removing energy, orinother words tocouple ittothe external circuit. 
 NewYork. 1973. 24.Tri7l1a.D.B.J.C.Moore. 
 Information accu- mulated through experience onalarge number ofsystems can bepre- sented most easily byoutlining the development ofsuccessful systems from theearly-idea stage onthrough totheir operational use. Two typical system developments are described inthis chapter: (I)ahigh-performance ground-based setforairsurveillance and control; and (2)the AN”/APS-10, alightweight airborne setforairnavigation. Considerations leading tothe selection ofthese systems areasfollows: 1.Substantial development and design effort went into both systems and important advances resulted. 
 This is the same kind of relative-phase-shift change with direction that is present for an antenna array and results in the antenna pattern. For ground echo the distance is doubled; so the pattern of an echoing patch of length L has lobes of width X/2L. This compares with \IL for an antenna of the same cross- range length. 
 Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21   blind folio 21.42 ch21.indd   42 12/17/07   2:51:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 1-9. March, 1955.  54. 
 Vivekanandan, R. M. Wakimoto, and R. 
 ¤ ¦¥³ µ´$$$ SINP ´ ´          (ISTORICALLY   ) AND 1 PHASE AND GAIN CORRECTIONS HAVE BEEN PERFORMED USING  ADJUSTMENTS IN THE ANALOG SIGNAL PATHS  AS SHOWN IN &IGURE  'AIN ERRORS MAY  BE CORRECTED BY A CHANGE IN GAIN IN THE )& OR VIDEO STAGES OF EITHER OR BOTH  ) AND 1  CHANNELS 6IDEO GAIN CONTROL MUST BE IMPLEMENTED WITH CARE AS IT CAN EXAGGERATE THE NONLINEARITY OF THOSE STAGES 4HESE CORRECTIONS CAN NOW BE IMPLEMENTED MORE PRECISELY IN THE DIGITAL DOMAIN ! MEASUREMENT OF THE SIGNAL SPECTRUM AT THE CENTER OF THE )& BANDWIDTH INDICATES  THE DEGREE OF GAIN AND PHASE IMBALANCE COMPENSATION (OWEVER  AS THE FOLLOWING DISCUSSION WILL EXPLAIN  THE SUPPRESSION OF IMAGE ENERGY ACROSS THE )& BANDWIDTH MAY BE SUBSTANTIALLY LESS THAN INDICATED BY THIS MEASUREMENT AT )& CENTER 4IME $ELAY AND &REQUENCY 2ESPONSE )MBALANCE  )F THE RESPONSES OF THE   ) AND 1 CHANNELS ARE NOT IDENTICAL ACROSS THE ENTIRE SIGNAL BANDWIDTH  UNWANTED IMAGE  RESPONSES WILL OCCUR THAT ARE FREQUENCY DEPENDENT /PTIMUM BANDPASS FILTERING SHOULD  &)'52%  )1 DEMODULATOR WITH GAIN  PHASE  $# OFFSET  AND TIME 
 9. Clarke, J.: Airborne Early Warning Radar, Proc. IEEE, vol. 
 AES-4), November 1968, pp. 168–174. 35. 
 -- 
 Rotation of this disk alternately provides inductive or capacitive loading of the  resonators to raise arid lower the frequency.' The rotating disk is mounted on bearings inside  tlie vacuum and coupled to a rotating mechanism outside the vacuum. The Amperex X-band  DX-285 spin-tuned magnetron covers a 500-MHz band in an approximately sinusoidal  mariner at rates up to 1OOO times per second, equivalent to frequency tuning rates of the order  of I MHz per microsecond.  A coaxial rnagrlctron may be tuned by mechanically positioning in the coaxial cavity a  noncontacting washer-shaped metal ring, or tuning piston, as illustrated in Fig. 
 The unique characteristics of an array antenna offer the radar systems designer capabili-  ties not available with other techniques. As with any other device, the array will see ~nqjor  applicatioti when it can perforni sorne radar function cheaper than any other antenna type or  when it can do something not practical by other means.  REFERENCES  1. 
 I give these figures because for all prac-  tical purposes they cover the present range of radar,  from about a tenth of a mile up to 186 mules, by direct  ' reflection. There are several long-range systems, such  as Loran, where radar is effective up to many hundreds  of miles, but here the technique is somewhat different,  and as these long-range systems are described in a later  section of this book we can neglect them here in our  basic discussion of radar.  If we are to time anything by radio waves, however,  it will be obvious that we shall need some stop-watch  ‘which can deal with very minute periods of time, ranging  from about s$5 second down to about a millionth of a  - second. 
 ● Serial production of electronically scanned phased array radars. ● Inverse synthetic aperture radar (ISAR) that provided an image of a target as needed  for noncooperative target recognition of ships. ● Doppler weather radar. 
 In such situations the  hlTI signal processor milst have tile capability of placing separate rejection notches at the  dolyjlet fr cqucrlcics of tlic cli~ttcr." ''  4.12 O'TtiER 'TYPES OF MTI  'i'wo-frequency MT1.78.79 The first blind speed of an MTI radar is inversely proportional to the  carrier frequency, as described by Eq. (4.8). This can result in the appearance of many blind  speeds in conventional MTI radar that operate at the higher microwave frequencies. 
 C. Schleher, “LPI radar: Fact or fiction,” IEEE AES Magazine , vol. 21, no. 
 ( From Olin and Queen. ;o)  cross section than microwaves because the dimensions of the scattering objects are compar­ able to the wavelength and produce resonance effects.  An example of th~ measured radar cross section of a large ship (16,000 tons) is shown in  Fig. 
 BAND SIGNAL LEVELS ARE A CON 
 (a) Block diagram ofsystem showing location ofphase-shift unit. (h) Simplified block diagram ofphase-shift unit Inthe noncoherent method the local oscillator does not have tobe stabilized since phase changes are not tobedetected. Ho~\-everj the transmitter must have the same stability asinthe coherent method because theoverlapping ground clutter beats ~vith itself ifthetransmitter frequency varies from pulse topulse. 
 ................................ ................  5  PULSE MODULATION  ................................ 
 Four- and five-beam systems allow one to determine the quality of the measure - ments by detecting the presence of a nonuniform wind flow. Carbone, Strauch, and  Heymsfield187 and Strauch et al.188 address the issue of wind measurement error  in detail. The reader is referred to the review paper by Röttger and Larsen10 for a  thorough treatment of wind-profiler technology and to the sequence of Tropospheric  Profiling Symposia for tropospheric profiling applications of winds and other mete - orological parameters.189 Spaced Antenna Techniques. 
 R. Drinkwater, and A. Stoffelen,  “The advanced scatterometer (ASCAT) on the meteorological operational (MetOp) platform:  a follow-on for European wind scatterometers,” Canadian J. 
 !TLANTIC ISLAND 4HE COVERAGE REGIONS NUMBERED n CORRESPOND TO SKYWAVE RADAR MISSIONS AS FOLLOWS    AIR ROUTE MONITORING   BARRIER SURVEILLANCE   STRATEGIC WATERWAY MONITORING   BALLISTIC MISSILE LAUNCH DETECTION AND   REMOTE SENSING AND HURRICANE TRACKING 4HE SECTOR DESIGNATED  IS REPRESENTATIVE OF (& SURFACE WAVE RADAR COVERAGE.   (& /6%2 
 € Δx=R⋅γBW (5.17) pulse dur ation not resolved  nearly reso lved well reso lved . Radar Systems Engineering  Chapter 5 – Resolution and Accuracy  27        Figure 5.6  Angular resolution of two targets.   both targets in the main beamboth targets separated by the main beamboth targets outside of the main beam not resolved nearly resolved well resolved   Figure 5.7  Further examples for angular resolution. 
 DOPPLERS IE  DOPPLER FAR ENOUGH OUT OF MAIN 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 dynamos, resulting in an upward drift of the ionospheric plasma and its subsequent  descent along the geomagnetic field lines. The resulting electron density depletion at  the equator and roughly symmetric enhancements in the vicinity of ~ 20 ° N/S latitude  is known as the Appleton  or equatorial anomaly. 
 If the plot had been in terms of the angle q, the lobes would have been found to   increase in width as | q  | increased. The main beam occurs when sin q  = 0. The other  lobes have the same amplitude as the main beam and are referred to as grating lobes . 
 MATE IS RARELY IMPLEMENTED  ITS PERFORMANCE IS APPROACHED BY SIMPLE ESTIMATES 0RACTICAL $ETECTORS  -ANY DIFFERENT DETECTORS OFTEN CALLED  INTEGRATORS  ARE USED  TO ACCUMULATE THE RADAR RETURNS AS THE RADAR SWEEPS BY A TARGET ! FEW OF THE MOST COMMON DETECTORS  ARE SHOWN IN &IGURE  4HE FEEDBACK INTEGRATOR  AND TWO 
 17. Drerinan, L. E., and I. 
   
 The ADT  system generates tracks of more than one target by using a series of scan-to-scan target  measurements taken as the antenna samples the target paths. (iv) The multifunctional  phased-array radar tracks multiple targets by multiple independent beams, formed by  the same array aperture, that are allotted to different targets. This subsection is lim - ited to the design principles, driven by the threat requirements, of the dedicated radar  tracker.3,153 The ensuing subsection will refer to multifunctional phased-array radar. 
 Thatis,aconstant prfisnotneeded.Thematching ofthedelaytimeandthepulse repetition periodisnotcriticalasinanacoustic linebecause thetimingofthetransmitter pulsestartsthesweepofthestoragetube. Thechargetransferdevice(CTO)isasampled-data, analogshift-register thatmaybeused inMTIprocessors asdelaylines,transversal filters,andrecursive filters.3S-38Therearetwo basictypesofCTDs.Oneisthebucket-brigade device(BHO)whichconsistsofcapacitive storageelements separated byswitches. Analoginformation istransferred throughtheBBDat aratedetermined bytherateatwhichtheswitches areoperated. 
 The Clas- sify, Locate, and Avoid Wind Shear (CLAWS) project69 in 1984 clearly demon- strated that a 2-min advance warning using doppler radar and human interpreters can be achieved. The use of doppler radars operationally, however, will require completely automated detection algorithms. A second major problem is ground clutter. 
 BIT CODE &IGURE  B IS THE SAME  BUT FOR ONLY MAXIMAL LENGTH SEQUENCES OF LENGTH  CODE A SUBSET OF &IGURE  A   &IGURE A SHOWS A LOWEST TIME SIDELOBE  LEVEL OF n D" 4HE LOWEST SIDELOBE FOR THE MAXIMAL LENGTH SEQUENCE IS SEEN FROM &IGURE B TO BE ONLY n D"&)'52%     3UPERPOSITION OF THE AUTOCORRELATION FUNCTIONS FOR ALL  POSSIBLE  
 asinFig.11.20.Thisdevicegenerates abinarypseudorandom codeofzerosandonesoflength 2"-I,where IIisthenumberofstagesintheshiftregister. Feedback isprovided bytakingthe outputoftheshiftregisterandaddingit.modulo two.totheoutputfromoneoftheprevious stagesoftheshiftregister. Intheexample ofFig.11.20,theoutputofthe6thand7thstageare combined. 
 MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 processing scheme is given in Figure 5.36. Multiple channels or phase centers are  digitized and pulse compressed. Periodic calibration signals are used to create a gain,  phase and beam steering correction table for all frequencies, antenna beam steering,  and channels, which are then applied to the digitized measurements in each channel. 
 Life: Although some magnetrons have short wear-out life, many others have short life because of mishandling by inexperienced personnel. Dramatic in- creases in average life have been obtained by improved handling procedures and proper operator training (Sec. 4.4).I3J4 10. 
 16.15 MTI improvement factor for a step-scan compensation of a single-delay canceler as a function of the number of hits per beamwidth. The antenna pattern is (sin JC)/*.SCAN COMPENSATION NO COMPENSATIONIMPROVEMENT FACTOR (dB) . 20 dB/decade; for the first-derivative*-type step-scan compensation, at the rate of 40 dB/decade; and with first- and second-derivative compensation, at the rate of 60 dB/decade. 
 AVIA 26/780)[5] Hendrie A 2010 The Cinderella Service, RAF Coastal Command 1939 —1945 (Barnsley: Pen and Sword Aviation) [6] Radley C 2016 Sonobuoy History from a UK Perspective (Clive Radley)Airborne Maritime Surveillance Radar, Volume 1 8-6. 
 TO 
 The fluctua-  tions widen the spectrum by modulating the echo signal. In a particular case, it has been  reported12 that the aircraft cross section can change by 15 dB for a change in target aspect of  as little as fO. The echo signal from a propeller-driven aircraft can also contain modulation  components at a frequency proportional to the propeller rotation.'' The spectrum produced  by propeller modulations.is-more like that produced by a sine-wave signal and its harmonics  rather than a broad, white-noise spectrum. 
 However, there is evidence indicating that nonthermal biological effects also  occur from exposure to microwave radiation.68 Pulsed power can produce biological change  not obtained with CW power of the same average value. Therefore, the possibility of dan-  gerous effects with excessively high peak 'powers should not be overlooked even if the average  power is less than the safe threshold. There has been, however, no direct link made between  biological effects attributed to nonthermal microwave origin and an adverse effect in humans. 
 7.4isidentical inprinciple \vith thechart projector shown asFig. 7.1. The virtual image formed inthis case, however, is that ofanedge-lighted screen \vhich can beengraved \vith ascale oraset ofindices. 
 CHAPTER 9 ANTENNAS, SCANNERS, AND STABILIZATION BY W. M. CADY, C.V.ROBINSON, F.B.LINCOLN, AND F.J.MEHRINGER The antenna isthesensory organ oftheradar set. 
 Foster. K.: Parabolic Cylinder Aerials, Wireless Et~gr., vol. 33, pp. 
 D. Stuart, and C. K. 
 However, the Dolph-Chebyshev function is physically unrea- lizable39'41'42 for the continuous spectra under discussion. Item 3, Taylor weighting, provides a realizable approximation to Dolph-Chebyshev weight- ing. Time sidelobes have little decay in the region B\t\ \ n - 1 but decay at 6 dB per octave when B\t\ h n. 
 DOMAIN MODELS  RAY TRACING  INTEGRAL TECHNIQUES  METHOD OF MOMENTS -O-   AND DISCRETE ELEMENT METHODS 4HE &INITE 
 When the clutter-doppler-frequency compensation cannot be obtained  0 001 0 01 0 1  oc'fp  Figure 4.34 Effect of a nonzero clutter doppler frequency on the improvement factor of a three-pulse  canceler. f, = mean frequency of the clutter spectrum, o, = standard deviation of clutter spectrum,  .f, = pulse repetition frequency. (From Andrews6')  MTIANDPULSE DOPPLER RADAR141 takenasMJ,thenM~isameasure ofthewidthofdoppler frequency spectrum. 
 The corresponding altitude difference is computed by  replacing d  (∆f) by 2p in Eqs. 17.58 and 17.59. Vertical antenna separation (no banking) :  ∆h ambigR nL( ) =λ (17.63) Horizontal antenna separation :  ∆h ambigR nL( )cos sin( )=+λ ψ ψ γ (17.64) Although we have derived these relationships for a single monochromatic pulse, they  can be shown (see Section 8.1.5 of Sullivan1 and Sections 3.0 and 9.3 of Carrara et al.3)  to be true for SAR pixels also, with l replaced by c/favg. 
 The output of the subtracter is a digital bipolar signal that contains moving targets, system noise, and a small amount of clutter residue if clutter cancellation is not perfect. The absolute value of the signal is then converted to analog video in a digital-to-analog (DIA) converter for display on a PPI. The digital signal may also be sent to automatic target detection circuitry. 
 They are present in pulse radar because doppler is measured by discrete samples  (pulses) at the prf rather than continuously. If the first blind speed is to be greater than the  maximum radial velocity expected from the target, the product )JP must be large. Thus the  MTI radar must operate at long wavelengths (low frequencies) or with high pulse repetition  frequencies, or both. 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.52  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 Although the dynamic range of the raw SAR data out of a BAQ operator is severely  limited, the potential dynamic range of the resulting image data is much larger: it is  bounded above by the product of the input dynamic range and the two-dimensional  compression ratio of the SAR data. Thus, the dynamic range capacity after processing  for Magellan  imagery was in excess of 40 dB. 
 (20.11). Because the receive beams in this technique are formed and processed simultaneously, the relative phase of the return between receive channels can, if desired, be used to aid the angle extraction accuracy. If it is used, the process is termed phase-coherent or simply coherent, and a close match in phase between receive channels must be maintained. 
 The less the bandwidth of the klystron, the greater can be its  efficiency.43 However, by use of harmonic bunching of the electron beam, high-power CW  klystrons of wide bandwidth have demonstrated efficiencies as high as 70 to 75 percent.8  The advantage of the klystron over other microwave tubes in producing high power is due  to its geometry. The regions of beam formation, RF interaction, and beam collection arc  separate and independent in the klystron. Each region can be designed to best perform its own  particular function independently of the others. 
 TION OF TEMPERATURE  PRESSURE  AND MOISTURE CONTENT #ONSEQUENTLY  IF SURFACE TEM 
 TARGET INDICATION -4)  OR $OPPLER RADAR   THE RATIO OF THE TOTAL ENERGY IN THE RECEIVED POINT CLUTTER RETURN AT THE INPUT TO THE PROCESSOR   TO THE TOTAL ENERGY IN THE POINT CLUTTER RESIDUE AT THE OUTPUT OF THE PROCESSOR  MULTIPLIED BY THE NOISE GAIN OF PROCESSOR. 
 This  -EXTRACTION OFINFORMATION ANDWAVEFORM DESIGN 417 - -- ---Td-----------------J (11) ; /. >, 7R // " f~ t+---_2 _T --~~ (b)Figure11.11(a)Pulsetraincon­ sistingoffivepulses;(b)ambi­ guitydiagram for(a). suchthatitispossible toignoreoreliminate anyambiguities whicharise.Thefactthatmost practical radarsemploythistypeofwaveform atteststoitsusefulness farbetterthanany theoretical analysiswhichmightbepresented here.Itisencouraging, however, whentheoreti­ calconsiderations substantiate thequalitative, intuitive reasoning uponwhichmostpractictll engineering decisions mustusuallybebased,forlackofanybettercriterion. 
 AP-35, pp. 553–561, May 1987. 33. 
 V.: Trimmed-Mean Iletcctor for Noncoherent Distributions, Nut~~l Rt~secirch Lohorc~torp  Rcport 6997, ~dsliinpton. D.C.. Occ. 
 MTJ AND PULSE DOPPLER RADAR 129  threshold from the 16 range cells and a clutter threshold from the clutter map are calculated  for filters 2 and 8 adjacent to the zero-velocity filter, and the larger of the two is used as the  threshold.  The advantage of using l wo prf's to detect targets in rain is illustrated by Fig. 4.28. 
 Another example45 is an L-band receiver protector using 10 PIN diodes mounted  in a coaxial line which was able to handle 1.6 MW peak power and 100 kW average power  with a 50 11s pulse width over a 10 percent bandwidth. The loss was 0.6 dB, isolation 70 dB,  turn-on time 2 11s and turn-off time 25 11s. Although the active diode-limiter offers many . 
 '0 >'-/16 Individual phasebit>'-/4,~, U >'/2Figure 8.6Cascadt:d four-hit digitally switched phaseshifterwithA/16quantiza­ tion.Particular arrangement showngives 135°ofphaseshift (~wavelength). oflinesandswitches required whenitisnecessary tominimize thequantization error.The parallel-line configuration hasalsobeenusedwhenphaseshiftsgreaterthan2nradiansare needed,asinbroadband deviceswhichrequiretruetimedelaysratherthanphaseshiftwhichis limitedto2nradians. " Thecascaded digitally switched phaseshifter(Fig.8.6)hasseenmoreapplication thanthe parallel-line configuration. 
 57. E. L. 
 These modifications areintroduced inamanner indicated inFig. 5.5 which shows ablock diagram ofthe system. Everything isstraight- forward, except for the local-oscillator power which isobtained by modulating the transmitter and selecting asuitable sideband bymeans ofabandpass filter. 
 "ISTATIC 2ADARS v IN  )NT  2ADAR #ONF  0ARIS    PP n  ! &ARINA AND % (ANLE  h0OSITION ACCURACY IN NETTED MONOSTATIC AND BISTATIC RADAR v  )%%% 4RANS   VOL !%3 
 CIPLES HAVE FOUND A THOROUGH MATHEMATICAL TREATMENT SINCE THE LATE S  FOR A  BRIEF HISTORY OF ADAPTIVE ARRAYS  SEE 2EED FOR AN OVERVIEW OF  LEAST SQUARES ADAP 
 The guard channel mechanization compares the outputs of two parallel receiving channels, one connected to the main antenna and the sec- ond to a guard antenna, to determine whether a received signal is in the main beam or the sidelobes.26"28 The guard channel uses a broad-beam antenna that (ideally) has a pattern above the main-antenna sidelobes. A range-cell, doppler- filter by range-cell, doppler-filter comparison is made of the returns in both chan- nels. Sidelobe returns are rejected (blanked) when they are larger in the guard receiver, and main-lobe returns are passed without blanking since they are larger in the main receiver. 
 E. Fischer, “Standard deviation of scatterometer measurements from space,” IEEE  Transactions on Geoscience Electronics , vol. GE-10, pp. 
 Although the slots may be in either  the broad or the narrow wall of the waveguide, the narrow wall is generally preferred (edge  slots) so that,ttie waveguides may be stacked sufficiently close to obtain wide-angle scan  without grating lobes. The waveguide slot array antenna is more suited for one-dimensiorial  scanning than scanning in two coordinates. This type of construction is also suitable for  r~iectiariically rotating antennas. 
 A constant phase shift can he inserted in the path  to each element, with a value that differs from element to element by amounts that are  unrelated to the bit size. This added phase shift is then subtracted in the command sent to the  phase shifter. With an optical-fed array, such as the reflectarray or the lens array, decorrela-  tion of the phase quantization is inherent in the array construction. 
 °xä  2!$!2 (!.$"//+   7 $ 7HITE  h4ECHNIQUES FOR TRACKING LOW 
 K. Brown, “Evolution of the satellite radar  altimeter,” Johns Hopkins APL Technical Digest , vol. 10, pp. 
 E., and 1. S. Reed: Theory of Adaptive Radar, IEEE Trans., vol. 
 f$Ec.16.6] INTERNAL CLUTTER FLUCTUATIONS 643 and half the pulse length, asshown inFig. 1618a. The individual targets may consist ofrocks, tree trunks, tree branches, leaves, etc. 
 W.: Heat Stress Due to RF Radiation, Proc. IEEE, vol. 57, pp. 
 N.. arid J. (;. 
 EARTH VELOCITY 
 on  Military Electronics C 01111. (IRE), 1958, p. 405. 
 Soc. Plroto-Optical lnstrtinrerrtatiorl Er~gi-  neers, vol. 128, "Erective Utilization of Optics in Radar Systems," pp. 
 TIVITIES DO NOT OCCUR IN NATURE  THIS DISTINCTION IS NOT EASY TO MEASURE %FFECTIVE PERMITTIV 
 AP-17, pp. 131-138, March, 1969.  96. 
 But an electronic difficulty is en-  countered, for what we are chiefly aiming to show on the  H2S tube is a true map-like picture of the scene beneath,  and we must counter the distortion introduced by the  differences in ranges, for a slant-range map introduces  inaccuracies akin to perspective distortion. If we can  calculate this distortion we can arrange to speed up or  slow down the time-base itself at precisely corresponding  . 142 HOW RADAR WORKS  ranges. 
   PP n  -ARCH   & 6 3CHULTZ  2 # "URGENER  AND 3 +ING  h-EASUREMENTS OF THE RADAR CROSS SECTION OF A MAN v  0ROC )2%  VOL   PP n  &EBRUARY   # 2 6AUGHN  h"IRDS AND INSECTS AS RADAR TARGETS ! REVIEW v  0ROC )%%%  VOL   PP n   &EBRUARY   * 2 2ILEY  h2ADAR CROSS SECTION OF INSECTS v 0ROC )%%%  VOL   PP n  &EBRUARY   , . 2IDENOUR ED    2ADAR 3YSTEM %NGINEERING  -)4 2ADIATION ,ABORATORY 3ERIES  6OL    .EW 9ORK -C'RAW 
 A primary advantage of this formulation of the equation is that standard curves for the parameter D0, as a function of the number of pulses integrated, are available, with the probabilities of detection and false alarm as parameters (Sec. 2.4). Calculation of these curves is necessarily done in terms of D0, the signal- to-noise ratio at the demodulator input terminals. 
 cc ¯ ¯   RECT FUNCTION RECT TT T    ª «­ ¬­   \ \  \ \   SINC FUNCTIONSINC   SIN    FF F PP  2EPETITION OPERATOR REP4 NXT XT N 4;  =  
 IRE. vol. 21. 
 £ä°È  2!$!2 (!.$"//+  )N THE FIRST  DRIFT SPACE  THOSE ELECTRONS SPEEDED UP DURING THE PEAK OF ONE CYCLE CATCH  UP TO THOSE THAT WERE SLOWED DOWN DURING THE MINIMUM OF THE PREVIOUS 2& CYCLE  4HE RESULT IS THAT THE ELECTRONS BECOME hBUNCHEDv PERIODICALLY 4HIS BUNCHING CAN BE THOUGHT OF AS PRODUCING A MODULATION OF THE DENSITY OF ELECTRONS 4HE BUNCHES PASS THROUGH THE INTERACTION SPACE OF THE SECOND CAVITY  WHICH REINFORCES THE  DENSITY  MODULATION TO ENHANCE THE BUNCHING 4HIS PROCESS OF IMPRESSING A TIME VARIATION IN VELOCITY THAT RESULTS IN BUNCHING OF THE ELECTRONS OF AN INITIALLY UNIFORM ELECTRON BEAM IS CALLED  VELOCITY MODULATION 4HREE OR MORE 2& CAVITIES MIGHT BE USED 4HE  INTERACTION GAP OF THE OUTPUT CAVITY IS PLACED AT THE POINT OF MAXIMUM BUNCHING SO THAT THE 2& POWER CAN BE EXTRACTED FROM THE DENSITY MODULATED ELECTRON BEAM BY A COUPLING LOOP IN A LOWER POWER TUBE OR BY A WAVEGUIDE NOT SHOWN  IN A HIGH POWER TUBE )N ESSENCE  THE DC ENERGY OF THE ELECTRON BEAM AT THE FIRST CAVITY IS CONVERTED TO 2& ENERGY AT THE OUTPUT CAVITY BY THE VELOCITY MODULATION PROCESS 4HE LARGER THE NUMBER OF CAVITIES THE GREATER CAN BE THE GAIN OF THE KLYSTRON 4HE GAIN OF A FOUR 
 R. H. Fletcher and D. 
 The simulation results of Figure 12a are consistent with the imaging geometry for the idealized anticyclonic eddy in Figure 1. When the radar look direction is 0◦and the current ﬁeld direction is counterclockwise, the longest spiral of the cyclonic eddy changes from dark to bright and then to dark, which is opposite to the brightness variations of the idealized anticyclonic eddy. Furthermore, the conclusion of two orthogonal look directions is in accordance with the analysis of an ERS-1 SAR eddy image in Ref. 
 ch15.indd   38 12/15/07   6:17:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter. 
 A coded group, or burst, of five 0.25 JtS pulses is also utilized. It ' ..... ~/,,l . 
 257–263. 122. L. 
 K. Livingstone et al., “Springtime C-band SAR backscatter signatures of Labrador Sea  marginal ice: measurements versus modeling predictions,” IEEE Trans. on Geosc. 
 K. Spencer, “Stochastic-constraints method in nonsta - tionary hot clutter cancellation, part II: Unsupervised training applications,” IEEE Trans. AES ,  vol. 
 This book was set in Times Roman.  The editor was Frank J. Cerra. 
 The number of pulses integrated is equal to the product of the pulse repetition frequency (PRF) and the time necessary to gener- ate the synthetic antenna. In turn, this time is equal to the ratio of synthetic length L to aircraft speed v. An expression in which the product of both factors has been written is iy. 
 Mesoscale Analysis Forecast. Symp., pp. 35-41, European Space Agency, Paris, 1987. 
 Any use is subject to the Terms of Use as given at the website. Sea Clutter.  SEA CLUTTER  15.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 where the constant A has been made explicit and Fp has absorbed a sin2 term from the  series. W(1) is the Fourier transform of the surface correlation function, which makes  it the sea wavenumber spectrum (discussed in Section 15.2) evaluated at twice the  (surface-projected) radar wavenumber, which defines a Bragg (or half-wavelength)  resonance . 
 Instead of the uniform panel sizes of Fig. 7.29, the space-frame radome can use a  quasi-random selection of different panel sizes to minimize periodic errors in the aperture  distribution which can give rise to spurious sidelobes. It also tends to make the ~adome  insensitive to polarization. 
 SPEED MOTION 4HEY PROCESS THE RECEIVED PHASE HISTORY WITH A hKEYSTONE FORMATTINGv PROCEDURE THAT ELIMINATES THE EFFECTS OF LINEAR RANGE MIGRATION FOR ALL GROUND 
 trouble istobeavoided.stage ofhard-tube pulser. 10c9. The Hard-tube Pulser.—A simplified diagram ofthe power- output stage ofthehard-tube pulser isgiven inFig. 
 Figure 14.1 illustrates seven basic echo sources  that might be found on a typical airborne target. All depend in varying degree on the  FIGURE 14.1   Examples of seven basic echo-source mechanisms ( after E. F . 
 The,frequency response function is proportional to sin2 n/,T.  A transversal filter with three delay lines whose weights are 1, - 3, 3, - 1 gives a sin3 nfdT  response. This is a four-pulse'canceler. 
 105, pp. 207-2l2.  35. 
 MONLY USED  THE ADVANTAGES AND DISADVANTAGES OF THE VARIOUS DETECTORS WILL BE STATED FOR THIS VIDEO -OVING 7INDOW  4HE MOVING WINDOW  IN &IGURE  A PERFORMS A RUNNING SUM OF  N PULSES IN EACH RANGE CELL    3 I   3I 
    COS    P       FOR THREE 
 This has made possible the devel - opment of pencil-beam tracking radars that meet missile-range instrumentation-radar  requirements of 0.003 ° angle-tracking precision. This chapter is devoted to tracking radar, but monopulse techniques are used in  other systems including homing devices, direction finders, and some search radars.  However, most of the basic principles and limitations of monopulse apply for all appli - cations. 
 However, the theory can  be qu ite complex. An understanding of the theory is essential in order to be able to specify and  operate primary radar systems correctly. The implementation and operation of primary radars  systems involve a wide range of disciplines such as building works, heav y mechanical and electrical  engineering, high power microwave engineering, and advanced high speed signal and data  processing techniques. 
 ¤ ¦¥³ µ´ 
 Signal processing includes the matched filter and the doppler filters in MTI and pulse doppler radar. Pulse com- pression, which is performed before the detection decision is made, is sometimes considered to be signal processing, although it does not fit the definition pre- cisely. Data Processing. 
 3.The many advantages ofashort pulse were thought tooutweigh any small increase incoverage which alonger pulse appeared to offer. 16.6. Pulse Recurrence Frequency .—The requirement ofanadequate time interval forpresentation ofdata usually serves tosetthe upper limit tothepulse recurrence frequency. 
 The slow-wave structure is designed so that an RF signal propagates at a  velocity near that of the electron beam. This permits an exchange of energy from the electron  hl'am to Ilic RF ficld lo produce amplification.;\ d-c electric field is applied between the anode  (slow-wave structure) and the cathode. t\ magnetic field is perpendicular to the plane of the  paper. 
 OF 
 The part of the spectrum that is useful for sky-wave propagation is densely populated. Even out-of-band signal levels are a consideration in receiver front- end design, where it is convenient to have band widths much wider than that of the radar signal. There are a large number of broadcast stations that have 500-kW transmitters and antennas with more than 20-dB gain. 
 Scharfman and G. August, “Pattern measurements of phased arrayed antennas by focus - sing into the near zone,” in “Phased Array Antennas,” A. A. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.78  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 32. D. 
 The result of the fusion is shown in Figure 14a. Figure 14b is a result of interpolation of the point in Figure 14a. It can be seen from Figure 14a,b that the imaging and fusion of images can be completed in a uniform coordinate system within a viewing angle range of −20◦to 20◦. 
 The azimuth angle, the ele- vation angle, and the range to the target were measured, and from the rate of change of these parameters the velocity vector of the target was computed and its future position predicted. This information was used to point the gun in the proper direction and to set the fuzing time. The tracking radar performs a similar role in providing guidance information and steering commands for missiles. 
 CAL OPTICS INTEGRAL YIELDS FALSE CONTRIBUTIONS FROM THE SHADOW BOUNDARIES  AS ALREADY NOTED -OREOVER  PHYSICAL OPTICS SHOWS NO DEPENDENCE ON THE POLARIZATION OF THE INCIDENT WAVE AND YIELDS DIFFERENT RESULTS WHEN THE RECEIVER AND THE TRANSMITTER ARE  INTERCHANGED 4HESE EFFECTS CONTRADICT OBSERVED BEHAVIOR &INALLY  IT ERRS BY WIDER MAR 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 the scatter from stem, bottom leaves, and soil to measurable but negligible size. 
  7(Z+   4S    SYSTEM NOISE TEMPERATURE  +  "N    DOPPLER FILTER BANDWIDTH ,# REFERS TO LOSSES THAT APPLY TO DISTRIBUTED SURFACE CLUTTER  AS OPPOSED TO DISCRETE   RESOLVABLE TARGETS 4HESE LOSSES WILL BE DISCUSSED IN 3ECTION  4HE CLUTTER 
 It was deployed starting in 1958 at seven  sites spanning the continental United States to detect and track noncooperative satel - lites.12,32 Transmitters are located at three sites, the largest of which transmits 1 MW  CW from a linear array about 3 km long, generating a fixed fan beam. The six receive  sites consist of seven or eight linear arrays with dimensions on the order of 1 km, also  generating fixed fan beams collinear with the transmit beam. Figure 23.4 shows the  data flow in a typical receiving station.12 ch23.indd   11 12/20/07   2:21:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Navigation G. General ground use Q. Special or combination K. 
 I'llere are several different types of crossed-field aniplifiers. Tltey all employ a slow-wave  circuit, cathode, and input and output ports. A schematic of a CFA is as shown in Fig. 
 ARRAY LEVEL  THE ANALOGUE TAPER  AT THE ELEMENT LEVEL TO ACHIEVE AN OVERALL TAPER MORE SIMILAR TO THE 4AYLOR ONE THIS  IS OBTAINED BY INCREASING THE CONTRIBUTION OF CENTRAL SUB 
 Heater power isfurnished byadry-disk rectifier and high-current filter. The optimum value ofecho-box coupling varies for different fre-. SEC. 
 Can. J. Remote Sens. 
 NOISE RATIO #.2  AT  NMI IS  ABOUT  D" &OR THE CONSTANT BEAMWIDTH ASSUMED  THE CLUTTER 
 ING WITH OR WITHOUT A MISSILE DATALINK OR BEACON  AND SEVERAL MODES TO RECOGNIZE TARGET NUMBER AND TYPE RAID ASSESSMENT AND NONCOOPERATIVE TARGET RECOGNITION USU 
 Wide dynamic range receivers need to be used to  avoid saturation. A logarithmic (log) receiver might help against noise jamming, but it has detrimen - tal effects against clutter when doppler processing is used. A log receiver is a device  whose video output is proportional to the logarithm of the envelope of the RF input  signal over a specified range. 
 ,Ê-* 
   PP n    3 / 2ICE  h2EFLECTION OF ELECTROMAGNETIC WAVES BY SLIGHTLY ROUGH SURFACES v  #OMMUN 0URE  !PPL -ATH  VOL   PP n    2EF   VOL ))  P   2EF   VOL ))  CHAP  2EF   VOL )))  CHAP   2 ( ,ANG AND * 3 3IDHU  h%LECTROMAGNETIC SCATTERING FROM A LAYER OF VEGETATION A DISCRETE  APPROACH v )%%% 4RANS  VOL '% 
 J. W. Bornholdt, “Instrumentation radars: Technical evaluation and use,” in Proc. 
 TIVE TO CONVENTIONAL APPROACHES WERE SHOWN 34!0 TECHNIQUES WITH TEMPORAL DEGREES OF FREEDOM SPACED AT THE 02) IE  SLOW 
 This can be accomplished by first estimating  the average target RCSk† at time tk, and then computing for each waveform i, the pre - dicted SNRk(i), and finally selecting the waveform index i such that the corresponding  SNRk(i) is just greater than the desired detection threshold plus a given tolerance.161 ECCM: A-SOJ and A-RGPO.  Hereafter, specific anti-SOJ  (A-SOJ) and anti- RGPO  (A-RGPO) techniques will be described. A-SOJ is based on estimating the jammer position and power level and then using  such estimates to adapt the radar detection threshold online. 
 21--23. 1975.  IFFI: Publication 75 CHO 938-1 AES. 
 [ CrossRef ] 20. Xie, P .; Zhang, M.; Zhang, L.; Wang, G. Residual motion error correction with backprojection multisquint algorithm for airborne synthetic aperture radar interferometry. 
 TIME AND SLOW 
 76. Jordan, E. C.: " Electromagnetic Waves and Radiating Systems," sec. 
 If it is assumed that each of the N elements in the array shares the gain equally, the gain of a single element is [Eq. (7.21)] 4-7T/4 GeW = -2^ COS O0 NK2 If the element is mismatched, having a reflection coefficient F(G, <$>) that varies as a function of scan angle, the element gain pattern is reduced to Gc(Q) = ^ (cos 0)[1 - IF(B, <|>)l2] The element pattern is seen to contain information pertaining to the element impedance.52'55 The difference between the total power radiated in the element pattern and the power delivered to the antenna terminals must equal the reflected power. In terms of the radiation patterns of the scanning array, this means that since the scanned antenna patterns trace out the element pattern, it follows that the average power lost from the scanned patterns is equal to the power lost from the element pattern because of reflections. 
 The conclusion that might be drawn from such experiments is that somewhat less than  theoretical integration improvement will be obtained if the pulses are not displayed properly;  that is, the persistence of the display should be sufficient to prevent excessive "loss of  memory," the dynamic range of the display must be large enough not to lose signal informa­ tion, and the display resolution should be consistent with the radar resolution to avoid  collapsing loss. Since the dynamic range of most displays is limited to a relatively small value,  the pulses received from a target should be displayed side by side (as is usually the case on a  PPI or B-sfope) rather than piled up at a single point on the display. In such a case the  integration is performed by the eye-brain combination of the operator. 
 POLAR CORRELATION COEFFICIENT OF  %H AND %V WHERE THE PHASE MEASUREMENTS  ARE ASSUMED TO BE TIME COINCIDENT  WHICH IS THE CASE WITH 3(6 TRANSMISSION AND RECEP 
 CAL CONVENIENCE IN CALCULATING TRACKING GAINS (OWEVER  MOST RADAR TARGETS DO NOT MOVE IN A RANDOM MANEUVER BUT INSTEAD MOVE LINEARLY AT TIMES AND THEN MANEUVER UNPREDICTABLY AT TIMES 4HE CHALLENGE IN ADAPTING THE FILTER TO DEAL WITH CHANGES IN THE TARGET MOTION EG  MANEUVERS  BALLISTIC RE 
 Ridenour, L. N.: u Radar System Engineering," MIT Radiation Laboratory Series, vol. 1, fig. 
 At the time of writing reference [ 3], February 1943, redesign of these aspects was still continuing. The Lucero equipment had two antennas, one on each side of the aircraft. Transmissions were synchronised with the radar using a PRF of 220 c/s. 
 and K. S. Kelleher: Recent Electronic Scanning Developments. 
 DELAY COHERENT CANCELER  ) IS THE  -4) IMPROVEMENT FACTOR FOR THE DUAL 
 Digital waveform generators are very stable devices with a well-defined dis- tortion. As a result, the generated waveform may be frequency-multiplied to achieve a much wider waveform bandwidth. With multiplication, the distortion components are increased in magnitude by the multiplication factor, and tighter control of the distortion is required. 
 ARRAY RADAR SYSTEMS IN SUPPORT OF THE  -EDIUM %XTENDED !IR $EFENSE 3YSTEM -%!$3  v  )%%% )NT 3YMP ON 0HASED 
 At any particular range, the filter notch is effectively at one frequency  and the center frequency of the clutter spectrum at another. The difference between  these frequencies results in a doppler-offset error, as shown in Figure 3.8. The clutter  spectrum will extend into more of the filter passband, and the clutter improvement  factor will be degraded. 
 20.2. 39. B. 
 266-275, July, 1956.  21. Mathur. 
 TO 
 #YR  AND . % 7OODS  h! RADAR OCEAN IMAGING MODEL FOR SMALL TO MODERATE  INCIDENCE ANGLES v )NT * 2EMOTE 3ENSING  VOL   PP n    $ 3 +WOH AND " - ,AKE  h! DETERMINISTIC  COHERENT  AND DUAL 
 C 0.1 0 ·.::  0  ::.,  C  ~  <1  0.01  0.00! -- /  2 /  /  / / I  I  I I n  I \  I \  I  4 6 10 20 40 60 100  Frequency, GHz 200  Figure 12.9 Attenuation or electromagnetic energy by atmospheric gases in an atmosphere at 76 cm  pressure. Dashed curve is absorption due to water vapor in an atmosphere containing l percent water  vapor molecules (7.5 g water/m3). The solid curve is the absorption due to oxygen. 
 No overseas stations are required if data is read out via relay satellites. Hence, the SBR system allows a country to be politically independent, and the loss of tracking stations in a foreign country has no impact on its system capa- bilities. The factors that affect the pace of development of large radar systems in space are: 1. 
 AA    WHERE YI  
 19.43 for a  large SNR and for narrow spectra, i.e., r(T) ≈ 1. The reader is referred to Zrnic ′85 for  further details regarding the estimation of other moments of the doppler spectrum. Pulse Compression. 
 However,  verification of receiver  performance under varying signal conditions  may not be  possible  using  the companion  transmitter. This requires a  generator with the capability to add impairments an d  distortions to generated pulses. Common  impairments  are in- channel  and out-of-channel  signals and  noise  to test  desensitization  or blocking. 
 The  equivalerit of a bank of contiguous bandpass filters may also be obtained by converting the  atinlog IF or video signal 10 a set of sarnplcd, quantized sigrials which are processed with  digital circuitry by means of the fast Fourier transform algorithm.16  A hank of overlapping doppler filters, whether in the IF or video, increases the complexity  the receiver. When the system requirements permit a time sharing of the doppler frequency  nge, the bank of doppler filters may be replaced by a single narrowband tunable filter which  searches in frequency over the band of expected doppler frequencies until a signal is found.  CWANDFREQUENCY-MODULATED RADAR77 FilterNo.41FilterNo.1~Del. 
 6 PLANE   SHOWING KEY &%4 DC PERFORMANCE LIMITS WITH OPTIMUM LOAD LINE FOR   POWER OUTPUT SHOWN (IGHER POWER OUTPUT IS ACHIEVED WHEN THE MAXI 
 The indicator screen isviewed through aninclined, partially reflecting piece ofglass which reflects tothe eye ofthe observer theimage ofascreen onwhich achart isprojected. Special coatings for glass have been developed which give ahigh reflectivity intheblue region ofthespectrum, while transmitting yellow light substantially without loss. Ifsuch acoating isused ontheinclined mirror, the yellow persistent signals onthe PPI tube can beseen with nearly their full intensity, while thechart image can beprojected onthe mirror inblue, sothat itisreflected with little loss inintensity. 
 2014 ,11, 1569–1573. [ CrossRef ] 21. Li, Z.; Liang, Y.; Xing, M.; Huai, Y.; Gao, Y.; Zeng, L.; Bao, Z. 
 ENDED WAVEGUIDES  A  
 POINT SAMPLES 4HE PROCESSING CAN BE PERFORMED WITH A DEDICATED DIGITAL SIGNAL PROCESSING COMPUTER OR BY FAST GENERAL 
 g201 ~15 ~10 ‘5 o 0 0 25 50 75 100 125 150 175 200 225 Rangeonsinglelargeawcraftinmiles FIG.15.4.—Desirable coverage for long-range air-surveillance radar. Insetting adesirable limit forthe upper contour fordetection ofa given type ofaircraft itwas, necessary tobalance the value ofhigh coverage against coverage inrange, since adding toone subtracts from the other unless the designer chooses toincrease the complexity ofthe equipment. For operations duting World War II,provision fordetection ofafour-engine plane atallaltitudes upto35,000 ftwas desirable, and this value was taken todetermine the upper section CD ofFig. 
 Brown, and B. Jaracz: Multi-Octave Double-Balanced Mixer, Microwaoe J., vol. 16, pp. 
 Figure 4.29. Transmitter and switching unit. A: waveguide switch unit; B: transmitter receiver; C: attenuator; D: amplifying units; E: control unit [ 20].Airborne Maritime Surveillance Radar, Volume 1 4-24. 
 vol.AES-3.no.6,Pl'.198-206, Nov.,1967. 118.Reed.J.E.:TheAN/FPS-H5 RadarSystem. Pmc.IEEE,vol.57,pp.324-335, March,1969. 
 È°£{  2!$!2 (!.$"//+  #HARACTERISTICS OF !MPLIFIERS AND -IXERS  .OISE FIGURE  AMPLIFIER GAIN  MIXER  CONVERSION LOSS   D" COMPRESSION POINT  AND THIRD ORDER INTERCEPT POINT ARE THE MOST  COMMON PERFORMANCE PARAMETERS SPECIFIED FOR AMPLIFIERS AND MIXERS /CCASIONALLY  A SECOND ORDER INTERCEPT POINT SPECIFICATION IS ALSO REQUIRED FOR VERY WIDE BANDWIDTH SIG 
 LIKE  OR  DISCRETE  RETURNS THAT VARY IN TIME !T THE HIGHER RESOLUTIONS   THE DISCRETE RETURNS TEND TO STAND WELL OUT OF THE BACKGROUND  OCCURRING FOR BOTH POLARIZATIONS BUT MOST CLEARLY EVIDENT WITH HORIZONTAL POLARIZATION AT SMALL GRAZING ANGLES 4HESE ISOLATED RETURNS ARE CALLED  SEA SPIKES AND ARE A COMMON CLUTTER COM 
 COMPRESSION 2!#  APPROACH  THAT ESSENTIALLY DOUBLES THE ACHIEVABLE PULSE LENGTH FOR  THE SAME CRYSTAL LENGTH )N AN 2!#  THE INPUT AND OUTPUT TRANSDUCERS HAVE A BROAD BAND 
 A lower bound on the transmit array aperture is set by the need to achieve adequate  directivity and hence power density on the target; the sensitivity required depends  on the size of the targets of interest. The upper bound is often set by the revisit  requirement—in general, the radar will step over a wide arc, but it must sample  each region frequently to maintain tracks on maneuvering targets, so the transmit  beamwidth should not be too narrow. The need to keep VSWR to modest levels is  usually addressed by having 2 to 6 arrays addressing subbands of about one octave  of frequency each. 
 'ROUND 
 P. J. Klass, “Navy improves accuracy, detection range,” Aviation Week and Space Technology ,  pp. 
 Hansen: Scanning Surface Wave Antennas: Oblique Strrface Waves over  a Corrugated Conductor, IRE Trans., vol. AP-6, pp. 370 .376, Octohcr, 1958. 
 This maximum value ofGweshall denote byGO. The narrow, concentrated beams which are characteristic of microwave radar require, fortheir formation, antennas large compared toawavelength. Innearly every case theradiating system amounts to anaperture oflarge area over which asubstantially plane wave isexcited. 
 CIATED COMMUNICATIONS INFRASTRUCTURE  AND THE CHALLENGE OF FINDING SUITABLE SITES WITH AN APPROPRIATE GEOGRAPHICAL RELATIONSHIP  BUT THEY ARE CONSTRAINED IN WAVEFORM CHOICE ANDOR RADIATED POWER BY THE NEED TO AVOID SIMULTANEOUS TRANSMISSION AND RECEPTION  AS WELL AS BEING POTENTIALLY SUSCEPTIBLE TO RANGE 
  TRANSMITTER AMPLIFIER MODULE  0HOTOGRAPH  COURTESY  OF  7ESTINGHOUSE %LECTRIC #ORPORATION  . 
 TALLY POLARIZED ELECTRIC FIELD MORE STRONGLY THAN THE VERTICALLY POLARIZED ELECTRIC FIELD (AILSTONES  HAVING AN IRREGULAR SHAPE  PHYSICALLY TUMBLE WHILE THEY FALL AND  THEREFORE  EXHIBIT NO PREFERRED ORIENTATION ON AVERAGE 4HUS  THE HORIZONTAL AND VERTICAL SCATTERED FIELDS HAVE NEARLY THE SAME AVERAGE VALUE 7IND -EASUREMENT  ,HERMITTE AND !TLAS  WERE THE FIRST TO SHOW HOW A SINGLE  DOPPLER RADAR CAN BE USED TO MEASURE VERTICAL PROFILES OF THE HORIZONTAL WIND FIELD WHEN PRECIPITATION IS PRESENT 4HIS TECHNIQUE IS MOST ACCURATE IF THE WIND FIELD IS UNIFORM IN THE REGION SCANNED BY THE RADAR 4HE METHOD DEPENDS UPON AN ANALYSIS OF THE RADIAL VELOCITY MEASURED DURING A COMPLETE SCAN IN AZIMUTH WITH A SINGLE FIXED ELEVATION ANGLE !T ANY SLANT RANGE  R  THE HEIGHT OF THE MEASUREMENT IS  R SIN @ AND THE RADIUS OF  THE REGION SCANNED IS  R COS @  WHERE @ IS THE ELEVATION ANGLE AS DEPICTED IN &IGURE   )F A IS THE AZIMUTH ANGLE   6 H IS THE HORIZONTAL WIND SPEED  AND  6F IS THE FALL SPEED OF THE  PARTICLES  THEN THE RADIAL VELOCITY AT RANGE R  IS GIVEN BY   6R A    6H COS A COS @   6F SIN @    ! HARMONIC ANALYSIS LEAST SQUARE FITTING THE AMPLITUDE  PHASE  AND OFFSET OF A SINU 
 28-31, 1974, IEEE Catalog No. 74 CHO 9340 NEREM, Library of Congress  Catalog no. 61-3748. 
 Because ofthecircular symmetry ofthereflector surfaceinthehorizontal plane, th~beamcanbe readilyscanned intheplanewithoutanydeterioration inthepattern. Thewavereflected fromthesurfaceoftheparabolic torusisnotperfectly plane,butitcan bemadetoapproach aplanewavebyproperchoiceoftheratiooffocallengthfto theradius ofthetorusR.Theoptimum ratioofIIRliesbetween 0.43and0.45.39 Goodradiation patterns arepossible intheprincipal planeswithsidelobes onlyslightly worsethanthoseofaconventional paraboloid. ThelargertheratioofliD,thebetterthe radiation pattern. 
 AES-7, pp.  1078-1086, November, 1971.  35. 
 Kwok, Y. Lo;  Artech Hous e Publishers; ISBN 0- 89006- 712-0  − Digital Beamforming for high Resolution Wide Swath Real and Synthetic Aperture  Radar; Marwan Younis, Forschungsberichte aus dem Institut für Höchstfr e- quenztechnik und Ele ktronik der Universität Karlsruhe, Band 42,    ISSN 0 942-2935  − C. Fischer, W. 
 4.29 are given in the  caption. 132 INTRODUCTION TO RADAR SYSTEMS  0.2  ......  at 0.1  0.05  2  0.02  0.01  0 5 10 15  Frequency, Hz 20 25 Figure4.29 Power spectra of various clutter targets. 
 ~(v) ~ !~ exp (-;: ) ( 13.10)  where a is the standard deviation of the enve~ v, which for the Rayleigh pdf is proportional  to the mean value. (The median value is vln 2 a.) Clutter which conforms to this model is  called Rayleigh clutter. The Rayleigh pdf applies to sea clutter when the resolution cell, or  area illuminated by the radar, is·relatively large. 
 5.13, and a photograph is shown in Fig. 5.14. The transmitter portion of the T/R mod- ule contains seven silicon bipolar power transistors, operated Class-C from a +31-V dc power supply. 
 ON INCIDENCE LIES AT ZERO 
 681-686, June 1974. 25. Anderson, S. 
 The 10/10 range was used for homing. 3.4 ASV Mk. IIIC The short Sunderland ﬂying boat was a very successful aircraft for long-range anti- submarine operations. 
 3684–3687, 2004. 180. L. 
 Aperture blocking may be reduced by decreasing the size of the subreflector. By making  the feed more directive or by moving it closer to the subreflector, the size of the subreflector  rnay he reduced without incmring a spillover loss. However, the feed cannot be made too large  (too directive) since it partially slladows the energy reflected from the main parabolic reflector. 
 ~A collapsing loss does not take place since noise from the other range intervals is  excluded.  A block diagram of the video of an MTI radar with multiple range gates followed by  clutter-rejection filters is shown in Fig. 4.19. 
 It must be remembered that at that time there was very little knowledge of the characteristics of sea clutter or targets at S-band and these were quite new observations. About one year later in August 1944, these trials were repeated by CCDU at RAF Angle using Wellington XIV and XII and Halifax II aircraft and radars as maintained by the RAF [ 15]. A considerable improvement in performance was observed, with the average detection range against Lundy Island from 3000 ft being 43.5 miles. 
 N. Levanon, “Stepped-frequency pulse-train radar signal,” IEE Proc-Radar Sonar Navigation ,  vol. 149, no. 
 We  can do this in one of three ways. We can move the  whole aerial and reflector. We can keep the big reflector  fixed and move the aerial itself; obviously this becomes  difficult at extreme ends of the traverse, where we shall  need to have the reflector specially shaped to produce a  constant field strength over the entire field of coverage. 
 Eng. Electron. 2015 ,37, 6–11. 
 STATE TRANSMITTERS HAVE LIMITED PEAK POWER AND THUS NEED TO OPERATE WITH A LONG PULSE AND A HIGH DUTY CYCLE  WHICH REQUIRE THE USE OF PULSE COMPRESSION 4HE LONG PULSE CAN MASK OR ECLIPSE TARGET ECHOES AT SHORT RANGE SO THAT AN ADDITIONAL SHORT PULSE TRANSMISSION IS NEEDED TO UNMASK THE ECLIPSED ECHOES AT SHORT RANGES 7HEN 3ENSITIVITY 4IME #ONTROL WHICH HAS A VARYING RECEIVER GAIN  WITH RANGE  IS USED WITH A LONG PULSE AND PULSE COMPRESSION  DISTORTION CAN RESULT IN  THE COMPRESSED PULSE )T HAS ALSO BEEN SAID THAT SOLID 
 2017 ,26, 2892–2904. [ CrossRef ][PubMed ] 4. Kang, M.; Ji, K.; Leng, X.; Xing, X.; Zou, H. 
 20, 1961. 36. Sherman, S. 
 and W.Y.; methodology, Y.W., W.Y. and H.K.; validation, Y.W., W.Y. and H.K.; writing—original draft preparation, Y.W.; writing—review and editing, W.Y.; supervision, J.C., W.L. 
 Another  source of error in the lens not found in reflector antenna is the variation in the properties of  the lens material. Both real and artificial dielectrics are not always perfectly uniform from  sample to sample or even within the same sample.  Figure 7.22 The "tin-hat" geodesic analog or a two­ dimensional Luneburg lens. 
 Lerner: Loss of Signal Detectability in Band-pass Limiters, IRE  Trans., vol. IT-4, pp. 34-38, March, 1958. 
 For example, a right- handed circularly polarized (RHCP) wave will be reflected as a left-handed circularly  ch21.indd   10 12/17/07   2:51:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 
 This 1s, of course, the Marconi  arrangement, where an aerial and earth (or counterpoise)  are connected in series with a tuned circuit to bring the  whole system into resonance with the desired frequency.  In the Hertz system we arrange that the aerial system  is self-tuned to the desired frequency, and a device  known as a feeder line (more colloquially a ‘trans-  mission’ line, when the conductor links a transmitter to  its aerial system) is used to connect the aerial array with  the first stage of the receiver or transmitter. There is  no need to elaborate on transmission-line theory in this  present volume, as it is a normal part of radio technique  and has already been adequately covered in The Amateur  Radio Handbook and in Section R of the Admiralty  Handbook of Wireless Telegraphy, to mention two out-  Standing examples. 
 SCALE APPLICATIONS REQUIRE PRECISION SUFFICIENT TO SUSTAIN SURFACE SLOPE MEASUREMENT ACCURACY ON THE ORDER OF  MICRORADIAN ONE MM SEA 
 13.) MT tfa = -p- (2.20) 1 fa where M is the number of pulses integrated and T is the pulse duration. This formula assumes that the integrator output is sampled at time intervals equal to T. If range gates are employed and M pulses are integrated, if the ON time of the gate tg is equal to or greater than the pulse length T, and if there is some fraction of the time 8 when no gates are open (dead time, e.g., just before, during, and after the occurrence of the transmitter pulse), then the formula is Mtg *f" = Pfa(l - 5) (2'21) These false-alarm-time formulas assume that the receiver predetection noise bandwidth Bn is equal to or greater than the reciprocal of the pulse length and that the postdetection (video) bandwidth is equal to or greater than 0.5 Bn (as it usually is). 
 POINT 
 There is some evidence that sea clutter might drop off more sharply below a critical angle in the neighborhood of a degree or so (see Long1). This critical angle, or critical range for a radar at a fixed height, has been observed from time to time since first noted in early observations of sea clutter.4 According to Katzin,37 the critical angle occurs as a result of interference between direct and (perfectly) reflected rays at the scattering targets responsible for the clutter signal. While this simple picture can account for the .R-minus-7 decay sometimes observed, a critical angle of- ten fails to materialize, and when it does, it need not show an /?-minus-7 de- crease with range (or the equivalent fourth-power dependence on grazing angle).1 An alternative explanation for this behavior, applicable at the higher microwave frequencies, has been suggested by Wetzel,12'38 based on a threshold-shadowing model for upwind and downwind directions that implies a sharp decrease in the average cross section for grazing angles below a few degrees. 
 14.5] VOLTAGE REGULATORS 565 Bell Telephone Laboratories developed aregulated exciter, type KS-15055, which weighed about 12lbcomplete and was meant foruse with the PE-218 inverter. (See Fig. 14.7.) Itregulated the 115-volt output toabout ~0.5volt rms, but had arather slow response and only fair temperature compensation. 
 (HF, or high-frequency region of the electromagnetic spectrum) to well beyond the optical region (laser radar). This is a frequency extent of about 1 billion to 1. The particular techniques for implementing a radar differ greatly over this range of frequencies, but the basic principles remain the same. 
 5.2. Table 5.2 illustrates some reported device applications and their general performance characteristics. A photograph of the 115-W UHF transistor used for the PAVE PAWS transmit- ter is shown in Fig. 
 STATE RADAR  CAPABLE OF SEARCH  THREAT DETECTION  CLASSIFICATION  AND PRECISION TRACKING AT LONG RANGES 4HE RADAR DESIGN DELIVERS HIGH POWER OUTPUT AND BEAMWAVEFORM AGILITY IN ORDER TO SUPPORT THE LONG 
 When thesuppressor isswitched on,most of the current transfers tothe plate, which experiences anegative surge that ispassed ontothecontrol grid. The sawtooth genera- tion then begins asindicated inthewaveform diagrams. The step atthebeginning ofthesawtooth isinsome cases detrimental and inothers useful. 
 Probably the biggest disadvantage is that they require very large computer  resources, both in terms of memory and execution times, particularly for applications  involving combinations of high frequencies, high elevation angles, high terminals,  and long ranges. In some cases, this computational burden can be reduced by combin - ing the best features of the various other models in a hybrid model. Once such model  is the Advanced Propagation Model (APM) described by Barrios.18 In APM, the PE  model is combined with various ray optics and other phenomena models to create a  hybrid model that can be up to 100 times faster than a PE model for stressful cases. 
 Extremely high currents may cause laminated brushes toexplode. Voltage dips ontheelectrical system can cause therelease ofvital relays orcontractors. To reduce the initial current surge aseries resistor (often anauxiliary series motor field) isadded. 
 DUCTING  AND NO ENERGY IS TRANSMITTED ACROSS THE BOUNDARY INTO THE BODY 7HEN ENERGY CAN PASS THROUGH THE SURFACE  TRANSMITTED RAYS ARE BENT TOWARD THE SURFACE NORMAL IN CROSSING A SURFACE INTO AN ELECTRICALLY DENSER MEDIUM HIGHER INDEX OF REFRACTION  AND AWAY FROM THE SURFACE NORMAL INTO A LESS DENSE MEDIUM 4HIS BENDING OF RAYS IS KNOWN AS REFRACTION $EPENDING ON SURFACE CURVATURE AND BODY MATERIAL  REFLECTED AND TRANSMITTED  RAYS MAY DIVERGE FROM ONE ANOTHER OR THEY MAY CONVERGE TOWARD EACH OTHER 4HIS DEPENDENCE IS THE BASIS FOR THE DESIGN OF LENSES AND REFLECTORS AT RADAR WAVELENGTHS AS WELL AS AT OPTICAL WAVELENGTHS 4HE REDUCTION IN INTENSITY AS THE RAYS DIVERGE SPREAD AWAY  FROM THE POINT OF REFLECTION CAN BE CALCULATED FROM THE CURVATURES OF THE REFLECTING SURFACE AND THE INCIDENT WAVE AT THE  SPECULAR POINT  WHICH IS THAT  POINT ON THE SURFACE WHERE THE ANGLE OF REFLECTION EQUALS THE ANGLE OF INCIDENCE 4HE PRINCIPAL RADII OF CURVATURE OF THE SURFACE ARE MEASURED IN TWO ORTHOGONAL PLANES AT THE SPECULAR POINT  AS SHOWN IN &IGURE  7HEN THE INCIDENT WAVE IS PLANAR AND THE DIRECTION OF INTEREST IS BACK TOWARD THE SOURCE  THE GEOMETRIC OPTICS 2#3 IS SIMPLY   R  PAA    WHERE A AND A ARE THE RADII OF CURVATURE OF THE BODY SURFACE AT THE SPECULAR POINT 4HIS FORMULA BECOMES EXACT IN THE OPTICAL LIMIT OF VANISHING WAVELENGTHS AND IS  PROBABLY ACCURATE TO  OR  PERCENT FOR RADII OF CURVATURE AS SMALL AS  K OR K )T  ASSUMES THAT THE SPECULAR POINT IS NOT CLOSE TO AN EDGE 7HEN APPLIED TO DIELECTRIC  OBJECTS  THE EXPRESSION SHOULD BE MULTIPLIED BY THE SQUARE OF THE VOLTAGE REFLECTION COEFFICIENT ASSOCIATED WITH THE MATERIAL PROPERTIES OF THE OBJECT )NTERNAL REFLECTIONS MAY ALSO BE ACCOUNTED FOR  AND THE PHASE OF INTERNALLY REFLECTED RAYS SHOULD BE ADJUSTED ACCORDING TO THE ELECTRICAL PATH LENGTHS TRAVERSED WITHIN THE BODY MATERIAL 4HE NET 2#3 SHOULD THEN BE COMPUTED AS THE COHERENT SUM OF THE SURFACE REFLECTION PLUS ALL SIGNIFICANT INTERNAL REFLECTIONS %QUATION  FAILS WHEN ONE OR BOTH SURFACE RADII OF . 
  n    n n  n n E 
 Aplotin rcctangular coordinates isshowninFig.5.th,andtheerrorsignalobtained fromatargetnot ontheswitching axis(reference direction) isshowninFig.5.1c.Thedifference inamplitude bctween thevoltages obtained inthetwoswitched positions isameasure oftheangular displacement ofthetargetfromtheswitching axis.Thesignofthedifference determines the. Time -+ Angle  (6)  Figure 5.1 Lobe-switching antenna  patterns and error signal (one dirnen-  sion). (a) Polar representation of  switched antenna patterns; (b) rect-  ( c angular representation; (c)error signal. 
 DERIVED DATA  NORMALLY AS TRACKED TARGET VECTORS BUT SOMETIMES AS THE RADAR IMAGE ITSELF 4HIS DATA IS OBTAINED FROM THE RADAR PROCESSOR VIA A DIGITAL INTERFACE  GIVING AN APPARENT CONVER 
 Some materials are more temperature-sensitive than others, but the material cannot always be  selected on this basis alone. Garnets are generally more temperature-stable and can handle  higher power than other ferrimagnetic materials. A reduction in temperature sensitivity can  be obtained with a composite magnetic cir~uit~~,~' in which the microwave ferrimagnetic  material is internal to the waveguide, but a temperature-insensitive, magnetic-flux-limiting  ferrimagnetic material is external to the waveguide. 
 During this process, the differences in phase received by each element of the linear array give the antenna pattern. In the synthetic antenna radar, on the other hand, a single element radiates and receives signals. Consequently, the round-trip phase shift is effective in forming the effective radiation pattern. 
 35IntheareaoffshoreofSanDiego, themedium valueoftheductthickness ascalculated from5yearsofmeteorological datais 6111.andasimilarcalculation fortheMediterranean Seais10m.36Measurements madeinthe Atlantic tradewind areaoffofAntigua showed ductsaveraging 6to15minheight.37The. 454 IN ~H0I)lJCTION TO KAIIAK SYSTI.MS  liciglit and strength of the duct was found to vary with wind speed. St rongcr winds gcricrally  resulted in stronger signals and lower attentlation rates. 
 RANGE RESOLUTION  ELECTRONIC COUNTER 
 NEGATION OPERATIONS OF &IGURE  C WORK TOGETHER TO STEER ) AND 1  SAMPLES INTO THE UPPER AND LOWER FILTER PATHS  RESPECTIVELY  BUT THE SAMPLES THAT ARE &)'52%   A  (ALFBAND BANDPASS FILTER COEFFICIENTS FOR A DIRECT DIGITAL DOWNCONVERTER   B  REAL ODD    AND C  IMAGINARY EVEN  PARTS OF THE COMPLEX IMPULSE RESPONSE                              
 47.  pp. 335-336, February, 1959. 
 FIGURE 14.4  Measured and predicted broadside RCS of a string stretched  across the test zone of an indoor test chamber at 45 ° angle ( © 1999 Horizon  House.7 Reprinted with permission .) FIGURE 14.5  Measured broadside returns of a thin dipole ( Courtesy of  University of Michigan Radiation Laboratory8) ch14.indd   7 12/17/07   2:46:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 
 Its results were disappointing and considerably below what had been predicted. The maximum ranges against afully-surfaced submarine (beam-on) were 7 miles at 1200 ft, 4 miles at 500 ft, and 5 miles at 200 ft. Following these trials it was con ﬁrmed that the 10 cm ASV radar was a de ﬁnite operational requirement, even though it was still only at prototype stage. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 
 12) which accentuate afairly strong echo relative toadiffuse background of clutter, this difficulty isplainly fundamental aslong asthere isnoessen- tialdifference between theechoes that make uptheclutter and theechoes from what wemay choose tocall the true target. How can the radar system distinguish between theechoes from boulders, ridges, trees, and a multitude ofirregularities ontheside ofahill, and theecho from atank moving down the hill? How can the periscope ofasubmarine beseen against thebackground ofechoes from aconsiderable area ofrough water?. SEC. 
 (7.26)  into the Fourier-transform relationship given by Eq. (7.14). The aperture distribution becomes  1 j2nnz A,(zl= - f ~~($1 exp (- d,=-,  256INTRODUCTION TORADAR SYSTEMS oA2A3A.11~ dddd d (a)sins6 Es(nA/d) .. 
 RIER FREQUENCY IS USED FOR !LERT AND #ONFIRM  THE TARGET 2#3 WILL BE RELATIVELY CONSTANT BETWEEN THE TWO DWELLS   PROVIDING ADDITIONAL RANGE ENHANCEMENT IN TERMS OF THE  CUMULATIVE PROBABILITY OF DETECTION -EDIUM 
  
 %##- USING PHASED 
 Byprovid- 4‘~~’~~‘~bSelenlum rectifiers Switch reversed oCRT /at0“and 180” Alternativef\--- feedback --- points /Switch reversed V6of at90”and27o” F]g.1344 FXG,1347,-Resolved-current PPIusing switched rectifiers, ingtwo rectifiers foreach secondary asindicated, only one point need be switched. Optimum smoothness atthe instant ofswitching isaccom- plished ifcontact ismade through the second rectifier before the first one isopened, sothat the circuit isnever broken. This method has the virtue ofextreme simplicity and inmany cir- cumstances itgives excellent performance. 
 Sack, M.; Ito, M.R.; Cumming, I.G. Application of e ﬃcient linear FM matched ﬁltering algorithms to synthetic aperture radar processing. Communications, Radar and Signal Processing. 
 Hence, correlation processing as shown in Fig. 10.Ic is equivalent to matched filtering. In practice, multiple delays and correlators are used to cover the total range interval of interest. 
 If two locally separated antennas are used then one no r- mally realizes the so- called Phase Monopulse Procedure.  The Amplitude Monopulse Proc e- dure will soon be described in more depth.  The antenna of amplitude monopulse Radar rad i- ates for determining the respective target angles θ und ψ of two separate, however correlated  directivity patterns. 
 Mechanically steered para- bolic reflector antennas (Chap. 6) and planar phased arrays (Chap. 7) both find wide application in radar. 
 10.46. Time contraction has not been applied to radar situations, as it requires an increased bandwidth for the compressed pulse. The stretch processing consideration will be restricted to time expansion of a linear-FM waveform. 
 ORDER LINEAR FILTER INITIALIZED FROM  F TJ     FOR A SUITABLE FILTER COEFFICIENT  @J       GA G AR OJ O JTTKJ KJKJ   
 RECTANGULAR AND RECTANGULAR 
 With circular polarization, the signal returned from a single-bounce target (i.e., a  sphere or flat plate) will require an antenna matched to the opposite sense of circular  polarization from that transmitted. If the same antenna is used, then single-bounce  targets are rejected. Such a system can, therefore, give a measure of suppression of  rain echoes,27 ideally amounting to  20 log ( e2 + 1)/(e2 − 1) dB  where e is the voltage-ellipticity ratio. 
 TO 
 E. Brennan, E. L. 
 TAINS A POINT TARGET WHOSE POSITION IS OSCILLATING SINUSOIDALLY VIBRATING  SEE 3ECTION  OF #ARRARA ET AL   4HE COMPONENT OF THE VIBRATION AMPLITUDE THAT IS PARALLEL TO THE LINE 
 LEVEL $"& IS USUALLY COST PROHIBITIVE EXCEPT FOR ARRAYS WITH A  SMALL NUMBER OF ELEMENTS (ENCE  SUBARRAY 
 67. Jao, J. K., and M. 
 Inaddition, themicrowave landingsystemandthewidelyused ATCradar-beacon systemarebasedinlargepartonradartechnology. Aircr~fiNavigatioll. Theweather-avoidance radarusedonaircrafttooutlineregionsofpreci­ pitation tothepilotisaclassical formofradar.Radarisalsousedforterrainavoidance andterrainfollowing. 
 SUPPLY 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar.  TRACKING RADAR  9.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 Complex targets can cause other phase relations as a part of the angle scintillation  phenomenon.1 The above error voltage, proportional to the ratio of the difference  signal divided by the sum signal, is the desired angle-error-detector output, giving a  constant angle error sensitivity.1 With limited AGC bandwidth, some rapid signal fluctuations modulate e but the  long-time-average angle sensitivity is constant. 
 KM SWATH WITHIN WHICH THEY BOTH HAVE COVERAGE  THEIR VERTICAL PROFILES ARE NEAR 
 DOMAIN MODEL FOR SEA SCATTER POINTS TO A POSSIBLE GENERAL SURFACE 
 13.48  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 parallel-feed network. Sum- and difference-pattern outputs are available, but they have  contradictory requirements for optimum amplitude distributions that cannot both be  satisfied. As a result, either good sum or good difference patterns can be obtained. 
   ,AWRENCE    & 4 5LABY ET AL  h 
 Tower and D. Lynch, “Pipeline High Speed Signal Processor,” U.S. Patent 4,025,771,  5/24/1977. 
 CALLED WIND PRO 
 TRACKING RADAR  9.496x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 32. I. D. 
 2010 ,45.[CrossRef ] 5. Liu, Y.; Fu, L.; Wang, J.; Zhang, C. Studying ionosphere responses to a geomagnetic storm in June 2015 with multi-constellation observations. 
 However, when the clutter returns are significantly nonhomogeneous, as is  the case for typical land clutter returns, the performance of the cell-averaging CFAR  will not be satisfactory and other means must be implemented to suppress the output  residues to the noise level. The traditional solution to this problem has been to deliberately reduce the receiver  dynamic range prior to the MTI filter to the same value as the maximum system  improvement factor. Theoretically, then, the output residue should be at or below the  normal receiver noise level, and no false alarms would be generated. 
 5.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 a ±50° azimuth scan.9,11,28 Usually, a fighter can’t engage at long range outside this  azimuth for kinematic reasons. The performance differences depicted in Figure 5.9 are the result of three factors:  the installed aperture can be 20% larger in net projected area at the aircraft in-flight  horizontal due to elimination of gimbal swing space, 2:1 higher radiated power due to  lower losses and better efficiency, and 60% lower losses before the low-noise ampli - fier. The other major advantage is that search volume can be changed dynamically to  fit the instant tactical situation, as suggested in Figure 5.9.28 The feed network is mundane but critically important. 
 Howard. D. D., S. 
 TERM BASIS S OF MSEC  /FTEN ANOTHER ADVANTAGE IS THAT BOTH THE NOISE FIGURE IS LOWER AND RADIATED POWER IS HIGHER FOR A GIVEN AMOUNT OF PRIME POWER 4HIS IS BECAUSE THE  2& PATH LENGTHS CAN BE MUCH SHORTER  WHICH USUALLY  LEADS TO LOWER FRONT 
 FORMANCE 4HESE EFFECTS MAY BE VISUALIZED WITH THE AID OF A HEIGHT VERSUS RANGE GRAPHIC AVAILABLE FROM AN ASSESSMENT SYSTEM SUCH AS !2%03 3UCH A GRAPHIC IS SHOWN IN &IGURE  )N THIS FIGURE  THE DIFFERENT SHADINGS CORRESPOND TO DIFFERENT PROPAGATION LOSS VALUES DEFINED LATER AS COMPUTED BY THE PROPAGATION MODEL  4HE ACTUAL VALUES ARE IMMATERIAL TO THIS ILLUSTRATION AS THE IMPORTANT FEATURES TO NOTE ARE THE CONSEQUENCES OF DUCTING )N THIS FIGURE  ONE CAN CLEARLY SEE THE NULL AND LOBE STRUCTURE RESULTING FROM MULTIPATH INTERFERENCE 7HILE A DISCUSSION OF DUCTING CONDITIONS UPON %- WAVE PROPAGATION IS USUALLY CONCERNED WITH PROPAGATION BEYOND THE NORMAL HORIZON  DUCT 
 When radar sys - tems use waveforms of widely varying bandwidths, different I/Q data rates may be  used to minimize the digital signal-processing throughput requirements. With differ - ent data rates comes the need to adjust the receiver filtering in order to avoid aliasing  signals beyond the Nyquist rate. Although these radars adjust their filtering to the  waveform bandwidth, they do not typically implement the matched filtering within the  receiver. 
 Then the signals at each range interval must be summed, as  expressed by the operation S, W, exp (jq5,). The processing is complicated by the fact that  n  the number of pulses to be summed is proportional to the range. Furthermore, the phase  correction in a focused SAR also depends on the range. 
 (NOTE: There are systems in which the lowest possible sidelobes are not desirable; for example, to minimize main-beam clutter or jamming, it may be better to tolerate higher sidelobes in order to achieve a narrower main-beam null width). To achieve low sidelobes, antennas must be designed with special tapered am- plitude distributions across their apertures. For a required antenna gain this means that a larger antenna aperture is needed. 
 K. Fung37) ch16.indd   15 12/19/07   4:55:12 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The lower aspect entropy value represents the scattering of a target is more concentrated. Targets of the same type have similar aspect entropy values because they have the same scattering mechanism. The aspect entropy of dihedrals and trihedrals extracted from the real data without denoising is close to 1, which is much higher than the simulation results in Section 2. 
 ATE RADIO FREQUENCY RADIATOR ,EGISLATION AND AN %43) PRODUCT SPECIFICATION MEANS THAT THIS EQUIPMENT WILL NEED TO CONFORM TO THE 2ADIO  4ELECOMMUNICATIONS 4ERMINAL %QUIPMENT 244%   $IRECTIVE )N THE SHORT TERM  UNTIL A NEW PROD 
 All components are digital processing blocks that can be implemented in various combinations of hardware and soft- ware. The complex value of the sampled signal V1-(O *s multiplied by the complex adaptive weight W11 to form the /th-channel input to the adder forming the undelayed antenna beam. The value is also routed to a buffer for storage. 
 Natural convection results ina transfer coefficient ofonly 0.006 to0.010 watts/in2 per ‘Cdifference in temperature between the airand the wall. If30”C betaken asasafe figure forrise ofinternal airover external air, and ifnatural convection beassumed onboth sides, then theaverage coefficient given above would result inamaximum thermal load of0.12 watt s/in2. Forced convection from agentle current ofairalong thesurface raises thecoefficient to0.02 watt s/in2 per“C,but beyond this increased velocity results inonIy aslow increase. 
 Field degradation. When a radar system is operated under laboratory conditions by engineer­ ing personnel and experienced technicians, the inclusion of the above losses into the radar  equation should give a realistic description of the performance of the radar under normal  conditions (ignoring anomalous propagation effects). However, when a radar is operated  under field conditions. 
 If the bistatic radar were to  provide volumetric coverage with directive antenna beams, the transmitting and receiving  heams would have to he scanned in synchronism. If the receiving beam is always to observe the  volume of space illuminated by the transmitted pulse packet, the receiving beam must he  scanned rapidly. Since the pulse packet travels at the speed of light, the receiving beam  sometimes must be scanned more rapidly than possible by mechanical means. 
 C.: Stereoscopic Synthetic Array Application in Earth Resource Monitoring, I EE£  NAECON '75 Record, pp. 125-132, 1975.  13. 
 AM sidebands are typically  120 dB below the carrier, as measured in a 1 kHz band, and are relatively constant across the  : •rJ m , 1' ~r t? f ··i .. i,t'·tf ... ···· ... 
 A chaligc it1 pliase car1 be obtained by utilizirig one of a  titrrtiI>er of lengtlis of tratisrriissioti lirie to approxirnate tlie desired value of phase. ?'he vario~is  Ictigtlis of liric 31-c iriscrtccl arid 1-etnovcd by Iiigli-speed electroriic switching. Semiconductor  diodes arid ferrites are the devices coriirnonly employed in digital phase shifters. 
 vol. 33, 1111. HZ 96, Ap~.il, 1956. 
 NATORS OF THE MAGNETRON  RESULT IN DIFFERENT MODES OF OSCILLATION 4HE MAGNETRON CAN SHIFT  ALMOST UNPREDICTABLY  FROM ONE MODE TO ANOTHER WHICH MEANS THE FREQUENCY SHIFTS UNPREDICTABLY  AS THE VOLTAGE CHANGES OR AS THE INPUT IMPEDANCE THAT THE MAG 
 Radar sounders should not be confused with (passive) microwave radiometers— also called sounders, unfortunately—that are used by operational meteorological  satellites to estimate atmospheric water distribution. A multifrequency radiometer  generates coarse water vapor density profiles for which altitude is a function of fre - quency. Passive microwave sounding units have mass and power requirements on the  order of 50 kg and 75 W, much less than their active radar counterparts. 
 The problem is the weakness of pulsar emissions, especially reemissions by asteroids and their reliable detection, which requires the development of highly sensitive sensors. From an astronomical point of view, it is very tough to detect the asteroid in the space by the narrow antenna beam of the radio telescope that is not able to cover the whole visible space. A network of multiple synchronized radio-telescopes located on the Earth’s surface and directed on di ﬀerent parts of space, or giant phase arrays antennas scanning the space, are needed in order increase the asteroid’s detectability. 
 22.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 Civil Marine Radar Andy Norris 22.1 INTRODUCTION In terms of the number of systems in worldwide use, civil marine radar (CMR) is the  largest radar market of all time. 
 3deals with the important matter oftheproperties ofradar targets. The usual inverse-square law which governs theintensity ofradiation from apoint source acts todetermine therange dependence ofthefraction ofthetotal transmitted energy that falls onatarget. Sofarastheecho isconcerned, thetarget can also bethought ofasapoint source ofradia-. 
 0 2r txcSmB     This allows v ery high resolution to be obtained with long pulses, thus with a higher average power.   Resolution Cell   The range and angular resolutions lead to the resolution cell. The meaning of this cell is very clear:  unless one can rely on eventual different Doppler  shifts it is impossible to distinguish two targets  which are located inside the same  resolution cell. 
 In the best case, the specific flight line or a first-level main - tenance replaceable assembly is identified with high probability. Such assemblies are  then sent to a depot for replacement, repair, failure tracking, and/or reclamation. For  assemblies that have a very low failure rate, it is usually cheaper to replace and reclaim  rather than repair even when the assembly is very expensive. 
 113, pp. 405-412, March, 1966.  39. 
 11.8.2  Covering with Radar absorbing material   Radar absorbing material (RAM), in order to have a  good absorption characteristic, must have  a minimum depth of approximately half of a wavelength.  Thus this possibility doesn’t exist  for airplanes.  Aboard ships the absorbing coverage is so extremely exposed to the enviro n- ment that the characteristics a re maintained for a longer period of time. 
 Strobe unit type 63 [ 1].Airborne Maritime Surveillance Radar, Volume 1 4-11. The mirror speed control controlled the rotation speed of the mirror, to a maximum of 40 rpm. The velocity meter registered when an echo had been locked-on and the range was decreasing, determined by the slant range, the height and the aircraftspeed. 
 82· 115 With  an element spacing of one-half wavelength, the quantization lobe will appear at sin 01 ~  sin V0 -1, with a value of  P k . I b n:2 l cos () 1 ea quant1zat10n o e ~ ---------4 228 cos 00 (8.34)  The peak sidelobes due to the phase quantization can be significant, and attempts should  be made to reduce them if their presence is objectionable. One method for reducing the peak  lobe is to randomize the phase quantization. 
 T. Lin, and L. J. 
 CM CYLINDER WITH  FACETS AT  '(Z   FOR THREE FIXED TRANSMITTER 
   . £n°{Ó  2!$!2 (!.$"//+  WHICH CORRESPONDS TO THE MINIMUM HALF 
 6.1 (Continued) (b) Principal-plane elevation pattern, (c) Contours of constant intensity (isophotes). (Courtesy of D. D, Howard, Naval Research Laboratory.) ELEVATION ANGLE db . 
 This can be a very time-consuming and expensive process, particu - larly when the antenna is mounted on an aircraft or other metallic object. Nevertheless,  complete patterns are a must for good scatter measurements. Range-Measuring Systems. 
 WollT. I.: 1)eterrnination of the Radiating System Which Will Produce a Specified Directional  Cliaractcristic, Proc. IRE, vol. 
 Values ofRfrom afew hundred toafew thousand ohms are usual. Inductance Lzischosen tooffer ahigh impedance attheintermediate frequency and issometimes made resonant atthis frequency. 12.6. 
 However, the relatively short range of most targets  of real interest means that the volume of the radar-illuminated precipitation is rela - tively low, helping to make the clutter rejection of the differentiator adequate for its  purpose. Such clutter varies approximately with the fourth power of frequency, and  so a 3 GHz system inherently experiences 19 dB less clutter than a 9 GHz system,  assuming identically sized clutter cells. For this reason, on ships fitted with both  3 and 9 GHz radars, the 3 GHz radar is often preferable, except when maneuvering  in close situations, for example, in harbors when the normally superior azimuth  resolution of a 9 GHz radar is preferred. 
 3.15. Structures.-The general appearance ofstructures and clusters ofbuildings isillustrated inFig. 3.25, which was obtained with ahigh- resolution system inthe region betlvccn Baltimore and Havre deGrace, Md. 
 PERFORMANCE ANTENNAS FOR 643 APPLICATIONS HAS A SIMILARITY TO  AIR TRAFFIC CONTROL ANTENNAS  IN THAT THEY BOTH IDEALLY REQUIRE A TAILORED ELEVATION PATTERN 4HE IDEAL PATTERN SHAPING FOR A HIGH 
 FIELD TEST FACILITY DURING ASSEMBLY 2EAR VIEW SHOWS DETAIL OF  EASILY REPLACEABLE LOWEST REPLACEABLE UNITS  #OURTESY OF ,OCKHEED -ARTIN #ORPORATION  . £Î°È{  2!$!2 (!.$"//+  4HE MAIN FEATURE OF THESE SYSTEMS IS THE PLANAR PHASED ARRAY  WHICH HAS MODULAR  CONSTRUCTION WITH DISTRIBUTED ALL 
 Croney. J., and A. Woroncow: Dependence of Sea Clutter Decorrelation Improvements Upon Wave  Height, IEE lt~t. 
 CALLED ! 
 Similarly, the adaptive cancellation of NLI received by the rhs auxiliary antenna  is reached by the linear combination of the SLC and SLB signals with the adaptive  weights W2 and 1, respectively; the adapted signal SLB' doesn’t contain the NLI. Once  the NLI is removed from the two channels, then the classic SLB logic can be applied  against the CRI by comparing the amplitude | MAIN '| of the main channel with that  |SLB'| of the blanking channel, which are both NLI free.72 Because the phase centers of the three antennas (the main and the two auxiliaries)  are spaced, in general, more than 0.5 l (where l is the length of the radiated EM  wave), the adapted patterns of the main and SLB channels fluctuate around average  curves due to the presence of grating lobes.72 Nevertheless, a reasonable gain margin  is present between the pattern of the adapted SLB and the sidelobes of the adapted  main antenna; thus, an adequate probability of blanking the CRI in the presence of  adaptively nulled NLI should be expected. In order to improve the above gain margin  and, consequently, the blanking probability of CRI, the following processing strategies  are suggested72,73: spatial and frequency diversity. 
 Many of these systems were developed, tested, or deployed prior  to 1980. Examples are the French, USSR, and Japanese forward scatter fences used  in WWII,2 the AN/FPS-23  for air-defense gap filling,2 PARADOP  and MIDOP  range- instrumentation trackers,9 SPASUR  for space surveillance,12,32 and Sanctuary  for  air defense.33,34 The BRWL  for artillery, mortar, and rocket location,35 the Russian  Struna-1  forward scatter fence,36–38 and the French Graves  for space surveillance39  were later developments. Omitted entries in the dedicated transmitter column for operation in the receiver-  and transmitter-centered ovals at large baseline ranges are dictated by operations  and cost: both cooperative and noncooperative transmitters-of-opportunity are often  present and capable of supporting bistatic operation in these small areas of interest. 
 Energy is piped to the aerial array from the trans-  mitter, and back to the receiver, by means of wave-  guides. Until about 1936 the only means for linking  radio equipment to the aerial was by means of a pair  of conductors. We had parallel pairs of transmission  lines, twisted wires, and then ‘coaxial’ feeders consisting  of a wire or tube inside another tube. 
 Februar\ 1957 .  .3. Friis. 
 M. Howells, “Adaptive-Adaptive Array Processing,” IEE Int. Conf. 
 47.Hartley-Smith, A.:TheDesignandPerformance ofaModern Surveillance RadarSystem. IEEE1975 International RadarC01!(erence, Arlington, Va.,Apr.21-23,1975.pr.306..311. 48.Edgar,A.K.,E.J.Dodsworth. 
 U. Nickel, “Monopulse estimation with adaptive arrays.” IEE Proc ., vol. 130, pt. 
 15. R. G. 
  
 By transmitting a longer Confirm   dwell for ranging only at beam positions where a shorter-dwell Alert  has detected  ch04.indd   36 12/20/07   4:53:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 CRAFT WHILE IT WAS OVER THE MOUNTAIN FACE  IT WOULD DISPLAY THE AIRCRAFT ON THE NEXT SCAN OF THE ANTENNA BECAUSE THE AIRCRAFT WOULD HAVE MOVED EITHER FARTHER OR NEARER 4HE 00) DOES NOT HAVE A RESOLUTION THAT APPROACHES THE RESOLUTION OF THE SIGNAL PROCESSING CIRCUITS OF THIS RADAR 4HUS  THE APPARENT EXTENDED CLUTTER HAS MANY WEAK AREAS NOT VISIBLE IN THESE PHOTOGRAPHS  WHERE TARGETS COULD BE DETECTED BY VIRTUE OF AN -4) RADARS INTERCLUTTER VISIBILITY DEFINED IN 3ECTION   Ó°xÊ 
 ORBITING SYNTHETIC APERTURE RADAR 3!2   RADAR ALTIMETRY WHICH IN  THE 3"2 CONTEXT ALMOST A LWAYS IMPLIES OBSER 
 A. Watson, T. Kirubarajan, and Y . 
 The product of these three factors gives the average power Pav. This relationship is written Pa, = /Vr,PRF (21.57) In the design of a radar system, the bandwidth B is chosen to be the reciprocal of T0. Hence the product of the bandwidth and the compressed pulse width is ap- proximately equal to unity. 
 1964  54. Crichlow, W. Q., D. 
 RANGE REQUIREMENT IS DRIVEN BY THE MAIN 
 TO 
 C. Dobson, “Improved spatial mapping of rainfall events with  spaceborne SAR imagery,” IEEE Trans. , vol. 
 DETECTION ALGORITHM THAT COMBINES  A HIGH REFLECTIVITY FACTOR WITH ECHO HEIGHT AND UPPER 
 OFFSET FEEDS FACING A REFLECTOR EG  (* 
 AIR2ADAR !PPLICATION 2EQUIREMENTS !IRBORNE OR SPACEBORNE SURVEILLANCE ,ONG DETECTION RANGE ACCURATE RANGE DATA !IRBORNE INTERCEPTOR OR FIRE CONTROL -EDIUM DETECTION RANGE ACCURATE RANGE  VELOCITY  AND  ANGLE DATA 'ROUND 
 50.Shrader, W.W.:Moving Targetlndication Radar,IEEE74RecordNEREM, Pt4,pp.18-26, Oct.28-31,1974,IEEECatalog no.74CHO934-0NEREM. 51.Grisetti, R.S.,M.M.Santa,andG.M.Kirkpatrick: EffectofInternal Fluctuations andScanning on ClutterAttenuation inMTIRadar,IRETrans.,vol.ANE-2,pp.37-41,March,1955. 52.Steinberg, B.D.:TargetClutter,andNoiseSpectra, ptVI,chap.Iof"Modern Radar," R.S.Berko­ witz(ed.~JohnWileyandSons,NewYork,1965. 
 AIR ! 
 no. 6, June 1995.  6. 
 MOVING TARGETS 5NFORTUNATELY  CLUTTER DOES NOT ALWAYS HAVE WELL 
 The receiver can be tuned by changing the first LO frequency without disturbing the IF section of the receiver. Subsequent shifts in intermediate frequency are often accomplished within the receiver by additional LOs, generally of fixed frequency. Pulse-amplifier transmitters also use these same LOs to generate the radar carrier with the required offset from the first local oscillator. 
 24.9 and the CCIR Report 322 noise discussed in Sec. 24.7. An additional need is a method to determine path effects. 
 The sum and difference patterns can be obtained by connecting a hybrid junction to the  outputs of the two antenna feeds as described in Sec. 5.4. The sum pattern is used on transmit  and both the sum and the difference patterns are extracted on receive. 
 POWER GRIDDED TUBES  v 0ROC )%%%  VOL   PP n  -ARCH   2 3 3YMONS  h4UBES 3TILL VITAL AFTER ALL THESE YEARS v  )%%% 3PECTRUM  VOL   PP n   !PRIL   6 , 'RANATSTEIN  2 + 0ARKER  AND # - !RMSTRONG  h6ACUUM ELECTRONICS AT THE DAWN OF THE  TWENTY 
 transmission loss ch12.indd   12 12/17/07   2:31:14 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 
 When the radar is searchlighting a target with a jammer, a mode of operation sometimes called burnthrough, the range becomes R2 _ *V(A o- BJ n 9) K max ~ 4^ EfN^PjGj U*^ The important radar parameters are the average power, the time of observation, and the transmitting-antenna gain. The maximum range is squared rather than raised to the fourth power as in other forms of the radar equation. Note that in neither jamming example does the antenna aperture area enter explicitly. 
 REJECT OR SINGLE 
 L., Jr., K. R. Hardy, and K. 
 M WAVE HEIGHTS      66 (( ,OW GRAZ  ANGLE,OW GRAZ ANGLE n     4HE 5NIVERSITY  OF -ICHIGAN  %%  #3 $EPT5LABY ET AL  6ISUALLY SMOOTH SAND  2OUGH SAND'RAVEL      66 ((  6( (6  6( (6 n  n   n   n    -)4 ,INCOLN ,AB  -!+OCHANSKI  3EA SEA STATE       6( 66   n       .ORTHEASTERN 5NIV  -!.ORTHEASTERN 5NIV  -!5NIV OF -!-C,AUGHLIN ET AL &ORESTED HILLS    3 BAND 3 BAND 66 ((6( (6&ULLY POLAR,OW GRAZ  ANGLE,OW GRAZ ANGLE n   n  n 4!",%  3UMMARY OF -EASUREMENT 0ROGRAMS FOR "ISTATIC 3CATTERING #OEFFICIENT  S" )N 
 H is  for these reasons that different design groups, in meeting the same user's requirements, often  produce different radar designs that bear little outward resemblance to one another, yet  accomplish the same objectives. ,_,;,,,; . TRANSMITTtR SITE  CJB .. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.100  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 logic permits retaining many of the targets with smaller radial velocities if their RCS  is large enough. SVC still rejects bird clutter, but retains, for example, the fast incom - ing, threatening low-RCS missile, while also retaining the larger cross-section aircraft  with lower radial velocities. 
 74. R. W. 
 COST OPTION )N GENERAL  THESE USE UNOFFICIAL VECTOR CHART DATA  ISSUED  BY SPECIALIST PRIVATE COMPANIES 4HIS DATA IS MORE AFFORDABLE THAN %.#S AND IS DIRECTED TO THIS PARTICULAR MARKET "ECAUSE OF COST AND SPACE CONSTRAINTS  A SINGLE DISPLAY NOR 
 R. Harrington, Time-Harmonic Electromagnetic Fields , New York: McGraw-Hill, 1961. 118. 
 The orbit is circular  at 100-km altitude. The radar transmits 200 µsec linear FM signals that are demodu - lated using the stretch technique, similar to radar altimeters. Each pulse is amplitude- weighted by a sine function (0, p  ) to suppress sidelobes by ∼30 dB from the surface  return that otherwise would mask the desired returns from depth. 
 6.17).. f$Ec. 69] EARLY AIRCRAFT-WARNING RADAR 179 Measurements ofangles ofelevation above about 7°were ambiguous onthis so-called “A” system, and measurements ofangles below about 1° were inaccurate owing tothe “flatness” ofthe height curve forthese small angles. 
 4.10 PULSE DOPPLER  RADAR'^  ?.  A pulse radar that extracts the doppler frequency shift for the purpose of detecting moving  targets in the presence of clutter is either an MTI radar or a pulse doppler radar. The distinc-  tion between them is based on the fact that in a sampled measurement system like a pulse  radar, ambiguities can arise in both the doppler frequency (relative velocity) and the range  (time delay) measurenients. 
 57. Robertson, J. W., and F. 
 4(% 
 The display isalways normalized tomake optimum use ofthe tube face. 1This hassometimes been called, erroneously, an“expanded azimuth” display.. SEC. 
 The ccnputer is cinematically equivalent toasmall replica oftheantenna mount which istobestabilized. The outputs arcthedeck-tilt correction and elevation angle foratwo-axis mount, ordeck-tilt correction and level and cross- level angles forathree-axis mount. They aremechanical butareconverted tovoltages bymeans ofsynchros, and control the servomechanisms which actuate themotors forthethree axes ofthemount. 
 Figure 8. Image rotation of 20 degrees. To solve this problem, we expansion the images in their edges with pixel pads to remove the black area. 
 Any use is subject to the Terms of Use as given at the website. Radar Cross Section.  RADAR CROSS SECTION  14.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 used when the incident electric field is parallel to the edge ( TM polarization ) and the  sum when the incident magnetic field is parallel to the edge ( TE polarization ). The divergence factor accounts for the decay in amplitude as the rays spread away  from the edge element and includes the effects of the radius of the edge if it is curved,  as at the end of a truncated cylinder, and the radius of curvature of the incident phase  front.35 The divergence factor for a two-dimensional edge (of infinite length) illumi - nated by a plane wave is Γ = 1/s. 
 The squared dependence for distributed scatter - ers is because the transmit pulse scatters power from all scatterers in the ct/2 pulse  volume (not just a single point target) thereby increasing the radar cross section of the  weather scatterer. PRFs for meteorological radars range from as low as several hundred s–1 for long- range detection to several thousand s–1 for shorter-wavelength systems attempting to  achieve high unambiguous velocities. Generally speaking, most meteorological dop - pler radars are operated in a single PRF mode, compromising the radar’s ability to  unambiguously resolve either range or velocity. 
 25.7. For targets of more complex structure, the extent of the pseudo-monostatic region is considerably reduced. A variation of the equivalence theorem devel- oped by KeIl41 applies to this case: for small bistatic angles, typically less than 5°, the bistatic RCS of a complex target is equal to the monostatic RCS measured on the bisector of the bistatic angle at a frequency lower by a factor of cos (P/2). 
 A method of airborne InSAR DEM reconstruction in layover areas. In Proceedings of the 2012 IEEE International Geoscience and Remote Sensing Symposium, Munich, Germany, 22–27 July 2012. 26. 
 Occasionally, receivers will include  filtering before the LNA in order to limit the effects of intermodulation distortion that  can occur in the LNA. Even when filtering is included before the LNA, a second filter  is often still required between the LNA and the mixer in order to reject the amplifier  noise at the image frequency. Without this filter, the noise contribution of a broadband  LNA would be doubled. 
 which can introduce a significant error. The use of a radar with high range- radar location  approx. radar  I  I  I  I  I  I  I  I  I  I  I  I  \ + I  I  11 _ corresponding zero  angle error voltage WV-2  super conste Ila tion  range video  angle video  time  Figure 5.20 Range and angle video obtained with the NRL High Range Resolution Monopulse {HRRM)  radar. 
 A waveguide device, suitable for the higher frequencies, that is analogous to the  line stretcher is the hybrid junction such as the magic T, short-slot hybrid coupler (sometimes  called the short-slot trombone phase shifter), or the equivalent in stripline.51 A change in line  length, with a corresponding change in phase, is obtained in the magic T with adjustable short  circuits in the' collinear arms. 56 The use of adjustable short circuits in the short~lot hybrid is  somewhat more convenient to configure mechanically.  Another electromechanical phase shifter which has been used in array radar is the  rotating-arm mechanical phase shifter.11.S us It consists of a number of concentric transmis­ sion lines. 
 E. Swartzlander and J. M. 
  
 ! SYNTHETIC 
 HOUR !LTHOUGH IT IS NOT SUBJECT TO THE STRINGENT AIR 
 SCAN FALSE 
 This configuration allows the receiver to integrate longer, subject to target/ cell migration limits, which, in turn, can recover some of the lost range performance of  the floodlight antenna. It also has the benefits of increasing data rates and simultane - ously servicing multiple receivers. It incurs increased sidelobe clutter levels, as well as  complexity and cost. 
 6.24. Relative height isaccurate toabout ~300 ftunder favorable conditions. Absolute height ismore difficult tofind accurately byradar, because ofthebending ofthebeam byatmospheric refraction, which varies from time totime. 
 THRESHOLDED TO REDUCE SENSITIVITY IN REGIONS OF UNACCEPTABLY HIGH ACTIVITY )N NO CIRCUMSTANCES ARE DETECTIONS ELIMINATED IF THEY FALL WITHIN A TRACK GATE IE  A GATE CENTERED ON THE PREDICTED POSITION OF A FIRM TRACK  &IGURE  ILLUSTRATES AN EXAMPLE  &)'52%   (ISTOGRAM OF DETECTION SIGNAL 
 J. P. Hansen and V . 
 26. R. Monzingo and T. 
 BEAM #LUTTER  4HE NET MAIN 
 W.: Wavcforin I>csipt~. cltap. 2 of " Ratl;~r Handbook." M. 
 We have investigated the spatial property of the echoed signal, and the spatial continuity model of the airborne radar system is constructed. By exploiting this spatial continuity knowledge, the forward and backward pulse information outside the observed CPI is well predicted based on the AR technique. Then the predicted pulses are merged together with the original pulses to form the newly merged pulses. 
 Coherent extended  range track  6. Coherent intermedi­ ate doppler  7. Coherent precision  range  8. 
 D" FREQUENCY RESOLUTION WIDTH TO  $F    4  4HE  
 A. Ericson, D. R. 
 Whereas angle of incidence  is used to describe results in studies where pointing  is nearer vertical, depression or grazing angle is a more appropriate description when  dealing with angles where incidence is closer to horizontal. Grazing angle is the com - plement of incidence angle. The measurements were all at low depression  angles, with  this term used in lieu of grazing  angle because it can be defined in terms of antenna  pointing, whereas grazing angle also depends on local slope, which is both variable and,  in general, unknown. 
 A. Weil in the second edition of Radar Handbook,48  the Conference Records of the International Power Modulator Symposia, and the  Conference Proceedings of the IEEE Pulse Power Conferences. The type of tube determines, to some extent, the type of modulator. 
 O.: Detection Performance of a Mean-Level Threshold, IEEE Trans., vol. AES-4, pp. 529-534, July 1968. 
 FED  DUAL 
 There are no formal standards governing intrumentation and measurement methods, but informal standards of good measurement practice have been recognized for de- cades. Depending on the size of the test object, the frequencies to be used, and other test requirements, measurements may be made in indoor test facilities or on outdoor ranges. Because one is seldom interested in the RCS of an object for only one aspect angle, all static test ranges use turntables or rotators to vary the target aspect angle. 
 The vertical-plane coverage diagram as illustrated in ﬁgure 1.6, while not representative of navigational radars, does indicate that at the lowerfrequencies the interference pattern is more coarse than the patterns forhigher frequencies. This particular diagram was constructed with theassumption that the free space useful range of the radar beam was 50nauticalmiles.Fromthisdiagramitisseenthattherangesoftheusefullobesare extended to considerably greater distances because of the reinforcementof the direct radar waves by the indirect waves. Also, the elevation of thelowest lobe is higher than it would be for a higher frequency. 
 (7.12), sin [(irfl cos B0)/\](B - B0)EW # '/2(1 + cos B)- -f— f- (7.14)[(TO cos B0)/\](B - B0) Equation (7.14) measures the angle B-B0 from the scanned direction. It shows that the effect of scanning is to reduce the aperture to the size of its projected area in the direction of scan. Correspondingly, the beamwidth is increased to Bo (broadside) Q 886 50 8BB (scanned) # = —f (rad) = ——-—- (deg) (7.15)cos B0 (a/\) cos B0 (a/K) cos B0 When the beam is scanned from broadside by an angle B0 < 60° and the aperture . 
 DELAY 
 PULSE  STAGGERING IS USED  IT LIMITS THE ATTAINABLE IMPROVEMENT FACTOR OWING TO THE UNEQUAL TIME SPACING OF THE RECEIVED CLUTTER SAMPLES 4HE CURVES IN &IGURE  AND &IGURE   WHICH HAVE BEEN REFERRED TO SEVERAL TIMES  GIVE THE APPROXIMATE LIMITATION ON ) CAUSED BY PULSE 
 Winslow, “Power dependent input impedance of field plate MESFETs,” Compound  Semiconductor Integrated Circuit Digest , pp. 240–243, 2005. 17. 
 TARRAYS  AS SHOWN IN &IGURE   WHERE AN OPTICAL 
 The principle units on ASV Mk. VIA were as for ASV Mk, VI except for: Strobe unit, type 63; Strobe control unit, type 454 (or 454A); Ampli ﬁer type A.3578 (for antenna split switching); Pilot ’s indicator 10A/16113 (range and azimuth meter); Leigh Light indicator 5T/517; Scanning unit, type 68. A block diagram of the main lock-follow functions in ASV Mk. 
 NUMBER  SPECTRUM COMBINED WITH A COS I   ANGULAR SPREADING PATTERN.   (& /6%2 
 However, if the entire angular region is swept within  a single pulse by a frequency-scan antenna, the response from a point target will be frequency-  modulated due to the finite beamwidth. A dispersive time delay filter can cause the received  echo to be compressed so as to achieve better range resolution. The amount of range-  resolution possible is limited by the finite time-delay of the signal propagating through the  frequency-scan feed network. 
 FILTER DOPPLER PROCESSOR  SOMEWHAT ANALOGOUS TO THE -4) IMPROVEMENT FAC 
 Clutter is not the only cause of detrimental performance of  marine radar. Direct reflections from a target arrive at the radar antenna and combine  vectorially with target reflections that have also been reflected by the sea’s surface.  This effect produces a summed signal at the radar antenna that is a function of both the  target height and the radar antenna height above the sea, as these affect the path length  difference of the direct and reflected radiation. 
 2. White, W. D., and A. 
 RANGE SPHERE OF RANGE  2 AND A CONSTANT VELOCITY CONE OF GENERATING ANGLE  A    COS n V6   WITH AXIS ALONG THE PLATFORM DIRECTION  IE  A CIRCLE OF RADIUS  2 SINA  AHEAD OF THE  PLATFORM A    n CORRESPONDS TO TARGETS BEHIND THE PLATFORM  7E SHALL  THERE 
 EST  MOST SOPHISTICATED PHASED ARRAY  ELECTRO 
 Allmicrowave development isrecognition ofthe impor- tance ofangular resolution. Aswavelength isdecreased, beamwidths obtainable with antennas ofpractical size are decreased. With the development ofamicrowave ground radar, the beamwidth foralong- range airsurveillance setwas pushed down byanorder ofmagnitude from values previously used forthis application, and results were spectacularly successful. 
 Debski and P. W. Hannan, “Complex mutual coupling measured in a large phased array  antenna,” Microwave J ., pp. 
 Sensors 2019 ,19, 743 Figure 6. Time-series subsidence at the ﬁve typical points A–E. The gray rectangle denotes the early summer (May, June, and July). 
 Utility ofC-w Systems.—In spite ofthe fact that c-w systems arelimited intheir rate ofinformation transmission they areofvalue fora number ofreasons. First, there areinstances inwhich arapid rate of transmission isofnoadvantage. Forexample, inthecase ofanaltimeter, there isone target, the earth. 
 98. Flock. W. 
  OR  
 5741, May 1986. 100. J. 
 _E = = = The required waveform inthepri- -FIG. 13.49.—Balanced-waveform generator mary isderived bythe introduc- using aninductance. tion, immediately following the sweep proper, ofasignal ofopposite polarity whose time integral is exactly equal tothat ofthe sweep. 
 However, most physical linear arrays are unfocused. This is sometimes stated by saying that the antenna is "focused at infinity." In a synthetic aperture radar, however, it is possible to focus each range separately by the proper adjustment of the phases of the received signals before the summation; this results in the effective synthetic aperture. Further- more, if desired, a different weighting can be applied to each range, although usu- ally the same type of weighting is used at all ranges. 
 The inverse Fourier transform (11) is a correlation procedure, searching for all Doppler components exp⎭parenleftBig −j2π·p·ˆp N⎭parenrightBig inside the spatial spectrum ˆS(k,ˆp), i.e., searching for that ˆpin the interval from 0 to (N–1 ) that reveal amplitudes by maximizing their intensities mod⎭bracketleftBigˆS(k,ˆp)⎭bracketrightBig , and compensate for all phases arg[ˆS(k,ˆp)]induced by the radial velocities, the motion of ﬁrst order, except phases proportional to the radial velocities (Doppler frequencies) of scattering points at the moment of imaging. The coordinate 112. Sensors 2019 ,19, 3344 ˆpis proportional to a constant radial velocity (Doppler frequency), that corresponds to the azimuth position of a particular scattering point at the moment of imaging. 
   3TANFORD 5NIVERSITY   3EPTEMBER   $ ( 3INNOTT AND ' 2 (AACK  h4HE USE OF OVERLAPPED SUBARRAY TECHNIQUES IN SIMULTANEOUS  RECEIVE BEAM ARRAYS v 0ROC !NTENNA !PPL 3YMP  5NIVERSITY OF )LLINOIS    3 * !NDERSON  9 ) !BRAMOVICH  AND 7 
 82,   pp. 503, 2001. 129. 
 PF     WHERE !R IS A DIMENSIONLESS AMPLITUDE SCALE FACTOR   TD IS THE TARGET TIME DELAY  S   FD IS  THE TARGET DOPPLER SHIFT (Z    AT  IS THE AMPLITUDE MODULATION  6   E T  IS THE PHASE  MODULATION RAD   AND  F IS THE TRANSMIT CARRIER FREQUENCY (Z  4HE COMPLEX ENVELOPE  OF SRT  IS    UT ! E U T TERRJFT DJF T TDD D     
 TOR OF I BY SHIFTING THE NUMBER TO THE RIGHT BY  I BITS  AND THEN ADDED TO OR SUBTRACTED  FROM THE ) OR 1  INPUT   DEPENDING ON THE SIGN OF  E 4HE VARIABLE  I IS INCREMENTED AND  THE PROCESS REPEATS UNTIL I   .  AT WHICH POINT THE PHASE 
 ING CLUTTER STANDARD DEVIATION IS  SPFRRF NF N    LN (Z    WHERE FR IS THE 02& AND  N IS THE NUMBER OF HITS BETWEEN THE ONE 
 ternperattlre sensitivity, and a not particularly good figure  Figure 8.12 Hysteresis loop showing the  principle of flux drive. where a single  ferrite toroid is excited by discrete  current pulses to produce digital phase-  shift increments from what is basically  an analog device.  IIII'I'I.ITIRON1CAI.IY SIITRH) I'IIASI'D ARRAY ANTI'NNA INRADAR295 Fluxdrin>..'4Thetoroid.ortwin-slab, ferritcphaseshiftermaybeGperated inananalog fashionbyvaryingthccurrcntofthedrivepulsesoastoprovidedifferent valuesofremanent magnetization. 
 Figure 5.2  Video pulse and added noise with edge trigg ering.    . Radar Systems Engineering  Chapter 5 – Resolution and Accuracy  25     The calculation of Δtr is performed similar to equation (5.5)   € Δtr=tr U02n2=tr 2SN (5.10)   tr is the linear rise time from 10% up to 90% of U0. 
 However, in the case of the microburst, it is the radial shear of the radial velocity that is  typically measured. Human interpretation of microburst signatures in color-enhanced  radial velocity displays is easily accomplished with trained observers50 and automatic  detection has been implemented on the TDWR radar system. Radial velocity differ - ences of 10 to 50 m/s are observed in microbursts. 
 382 THEMAGNETRON ANDTHEPULSER [SEC. 10.10 high enough forbreakdown. Current flows from 4’tothe disk pinand out through asecond spark atpgint A.The simplicity ofthis device is partially offset byanuncertainty ofupto~50psec infiring time, and by thenarrow voltage range over which satisfactory operation occurs. 
 69. McCarthy, J., J. Wilson, and M. 
 and H. P. Coleman: Applications of the Luneburg Lens, Naval Research Lab. 
  
 Adding M noise pulses, however, will result in an integrated noise pulse whose rms voltage is only VM times as great as that of a single noise pulse if (as is true of ordinary receiver noise and many other types of noise) the added noise pulses are not phase-coherent. Therefore the signal-to-noise voltage-ratio improvement is, ide- ally, MIvM = VM. Consequently the signal-to-noise power-ratio improvement, and the reduction of the single-pulse minimum-detectable signal-to-noise power ratio, is equal to M. 
 SOR AND AIR 
 ACCELERATIONS INTRODUCED IN STATE PROPAGATION #ARTESIAN%ARTH 
 Gaseous receiver-protectors ionize under transmitter power levels, but there is some small statistical variation in the initi- ation of ionization on the leading edge of the pulse and in its subsequent devel- opment. In radars demanding high clutter suppression (in excess of 50 dB), it has sometimes been found necessary to prevent this variable reflected power from being radiated by use of both a circulator and an isolator in the receive path. Spurious Responses of Mixers Mathematical Mixer Model. 
 Since the over-all characteristics ofthe radar system aresoclosely related to,and restricted by,the performance ofthe mag- netron, ageneral knowledge ofthe important characteristics ofmagne- trons isessential. Listed below with adiscussion ofeach are the characteristics of magnetrons ofparticular importance tosystem design. These charac- teristics arenot usually independent ofone another and their relation- ships arealso considered. 
 However, target resolution in the cross-range (angle) dimension can be obtained comparable with that obtained in range by the use of resolution in the doppler frequency domain. This requires that there be relative motion between the various parts of the target and the radar. It is the basis for the excellent cross-range resolution obtained in a SAR in which the relative motion between target and radar occurs because of the travel of the aircraft or spacecraft on which the radar is mounted. 
 D.: Low-Angle Radar Tracking in the Presence of Multipath, I £EE Tnms., vol. AES-10, pp.  835-852, November, 1974. 
 M. Staudaher, “Subclutter visibility demonstration,” Technical Report   RL-TR-92-21, Adaptive Sensors Incorporated, March 1992. 23. 
 THE 
 The output of the Mod is fed into the transmitter.  As the Mod is a central source of wave-producing  circuits the same Mod is used in some radar equipments  to produce wave-forms both for transmitter and receiver.  The Mod may thus be used as a sort of electronic key to  switch on and off the transmitter, as well as controlling  fundamentals of the receiver and the movements of the  CRT light-spot Its primary job, though, is to turn on  the radio-frequency oscillator of the transmitter, making  it oscillate violently for a millionth of a second or so,  then turning it off equally sharply and keeping it in  repose until the time for the next burst. 
 An increase of tempera­ ture with height is cal.led a temperature inversion and occurs when the temperature of the sea or  land surface is appreciably less than that of the air. A temperature inversion, by itself, must be  very pronounced in order to produce superrefraction. Water-vapor gradients are more effec­ tive than temperature gradients alone; thus superrefraction is usually more prominent over  oceans, especially in warm climates. 
 Thus the cooling liquid was in direct contact with the garnet for  efficient transfer of dissipated heat. Some of the highest power phase shifters have been  obtained with this design. For example, a C-band phase shifter, operating over an 8 percent  bandwidth was capable of handling 100 kW of peak power at an average power of600 W. 
 However, receiver saturation occurs at some signal level, and thus limiting inad- vertently exists.) The received signals are then compared in phase with the coho in a phase de-DUPLEXERPHASE DETECTORPRIMEMORY PULSED AMPLIFIERRF OSCILLATOR . FIG. 15.3 MTI system block diagram. 
 312INTRODUCTION TORADAR SYSTEMS Crossed -line directional coupler ~ '- '-(l) (l) > > Q..)..- WNu u (l) Q) a::: a:::'­ Q) > '(ijr0 u Q) a:::L (l) > .~<:j (l) a:::L (l) > (l)l[)u (l) a::: Figure8.26RFh.:am-forming lIsing tappedtransmission lin.:s. divideitspowerequally between thesametwoportswitha90°relative phasedifferencl:, and nopowerwillappearinthefirstport.Therelative p~asedifference inthiscaseisofopposite signcompared tothephasedifference resulting fromasignalintroduced intothefirstport. Consider asimpletwo-element arraywithhalf-wavelength spacing, connected tothetwo portsofa3-dBdirectional coupler asshowninFig.8.27.Ifasignalisinserted inportNo.1. 
 We also explore the relationship between height di ﬀerence threshold and system parameters. 3.1. The Error Model of ArcSAR Imaging on the Reference Plane As shown in Figure 2, the antenna rotates counterclockwise from S 1to S 2. 
 13.8] GENERA TION OF SHARP PULSES 501 longer falls, thefeedback action ceases, and thefirst grid rapidly increases inpotential, pulling the cathode positive. The second grid isthus cut offand the original condition restored. Since the plate falls atavery linear rate toafixed destination, thedelay time islinear with thepoten- tialfrom which itstarted itsdownward journey. 
 The h–pdcurves of the SAR image pair are shown in Figure 14. (a) The h–pd c u r v e  o f  A r c S A R  I m a g e  1             ( b) The h–pd curve of ArcSAR Image 2  Figure 14. The h–pdcurves. 
 yiekls  1 /\,.G,t 0E;(11) rr Bj  Rmax = 4 (S/N). j> .(;. Tr I IJ J (14.30)  where t 11 = 11r'.fr = integration time. 
 AGED NOT TO INSIST THAT THE RADAR DESIGNER USE SOME PARTICULAR TECHNOLOGY BECAUSE IT IS CONSIDERED THE FASHIONABLE THING TO DO AT THE TIME 4HEY MIGHT NOT ALWAYS BE GETTING THE BEST RADAR FOR THE PARTICULAR APPLICATION 4HERE HAVE BEEN AT LEAST THREE WAYS TO APPLY SOLID 
 It was also reported that trials by CCDU with service operators achieved an average range of 19 miles from 1000 ft on a surfaced submarine, in arange of sea conditions. Some of the locations referenced in these trials reports are shown in ﬁgure 4.32. In April 1944 CCDU reported [ 12] on trials to assess the performance of ASV Mk. 
 POWER 'A. (%-4S BATTLE FOR VACUUM 
 DWELL -4$  OPERATION IS A SYSTEM CONCEPT DECISION BOTH APPROACHES HAVE THEIR ADVANTAGES &OR EXAMPLE  PULSE 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 beams are generated. 
 ., . ,.'.  98INTRODUCTION TORADAR SYSTEMS signalsorthogonal. 
 Xing, X.; Chen, L.; Yuan, Z.; Shi, Z. An Improved Time-Series Model Considering Rheological Parameters for Surface Deformation Monitoring of Soft Clay Subgrade. Sensors 2019 ,19, 3073. 
 4(% 
 SEC. 11.10] REASONS FOR AN R-F PACKAGE 419 cuit with the standard intermediate frequency being used—for example, 30Mc/sec. Anerror inthedifference frequency produces avoltage that isapplied tothe reflector ofthelocal oscillator insucha sense astobring the local oscillator into correct tune. 
 ,Ê / 
 - 0!6% 0!73 5(& %ARLY 7ARNING 2ADAR   4HE 0!6% 0!73 !.&03 
 8.4 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 where the plus sign applies for a positive LFM slope and the minus sign for a negative  slope. The complex envelope of the LFM waveform is expressed in terms of the  amplitude and phase modulation functions as  u(t) = A rect( t/T )ejp a t2  Figure 8.2 shows an example of an LFM bandpass signal with a pulsewidth T = 10 µs,  swept bandwidth B = 1 MHz and time-bandwidth product equal to TB = 10. The LFM  slope is B/T = 0.1 MHz/µs. 
 (32) The formula Eq. (32) predicts asomewhat greater horizon distance than does thecorresponding formula fortheopticalhorizon, because the conditions assumed as“standard” include amoderate gradient ofwater- vapor concentration. Water vapor, although ithasbut aminor influence ontheatmospheric refraction ofvisible light, displays avery pronounced refractive effect atallradio frequencies, including microwave frequencies. 
 28 of "Antenna Theory, pt. 2," R. E. 
 The swath Sw is often much smaller than the  niaximirni range so that tlie prf car1 be increased to allow tlie umambiguous range Ru to  encompass file distance S, cos $. wliere $ is tlie grazing angle. Equation (14.12) becomes  sw C -< - 5'. 
 Sensors 2019 ,19, 2764. [ CrossRef ][PubMed ] 4. Zhou, Z.; Li, Y.; Wang, Y.; Li, L.; Zeng, T. 
 BAND OCCUPANCY DISTRIBU 
 Consequently this  possibility remains almost exclusively for use on land.  In practice reductions of 5 and 11 dB have been achieved.   11.8.3  Layering of the Outer -Surface Materials   On the boundary of two dielectrics aris es a reflection due to the ε-discontinuity. 
 OBSERVING 3"2S 3!2S AND RADAR ALTIMETERS  3EVERAL NATIONS ARE SPONSORING RADARS FOR EXPLORATION AT THE -OON AND BEYOND 3"2 
 DIMENSIONAL VECTOR CONTAINING THE SET OF SIGNALS  AT THE SAME RANGE BIN  FROM THE   . AUXILIARY ANTENNAS )T IS ASSUMED THAT ALL THE SIGNALS HAVE BANDPASS FREQUENCY SPEC 
 60. P. L. 
 267-270, July. 1957.  24. 
 One example is the transmitting  antenna pattern. APM will consider the full antenna pattern of the transmitting antenna.  FIGURE 26.13  AREPS radar window FIGURE 26.14  AREPS target window ch26.indd   24 12/15/07   4:53:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 C. E. Muehe, L. 
 282-332, 1944.  and vol. 24. 
 Low radar frequencies have the disadvantage that antenna beam-  widths, for a given-size antenna, are wider than at the higher frequencies and would not be  satisfactory in applications where angular accuracy or angular resolution is important. The  pulse repetition frequency cannot always be varied over wide limits since it is primar~ly  determined by the unambiguous range requirement. In Fig. 
 NOISE RATIO FOR THE CELL 
 RITHMS TO ESTIMATE THE UNAMBIGUOUS RADIAL VELOCITY OF A TARGET USING MULTIPLE 02& DWELLS DURING THE TIME OF TARGET WERE BECOMING PRACTICAL 4HESE  RADIAL VELOCITY ESTI 
 Conv.  Rec., vol. 8 pt. 
 39-45, June 1965. 4. Fenner, R. 
 Incases involving transmission from aircraft, certain interference effects described below are much ‘less troublesome atlow frequencies than atvery high frequencies. Insystems tested atthe Radiation Laboratory forthe transmission ofdata from anaircraft tothe ground, elementary antenna arrays have been used. One system, operating at300 Me/see, had avertically polarized dipole mounted onthetail section oftheaircraft and two verti- cally stacked dipoles atthe receiving station. 
 59. G. W. 
   
 (e) The linear decrease of temperature with height is −6.5º C per kilometer. The International Commission for Air Navigation (ICAN) uses the 1924 NACA  standard atmosphere, with minor modifications, primarily in the value of gravity and  the temperature of the isothermal region. For generic radar studies and other radar  applications, such as target height calculations for height-finding radars, it is the prop - agation through this standard atmosphere that is considered. 
 Sweep Centering Error If the origin of the sweep is not accurately centered on the PPI, bearing measurements will be in error. Greater bearing errors are incurred when thepipisnearthecenterofthePPIthanwhenthepipisneartheedgeofthePPI.Since there is normally some centering error, more accurate bearing measurements can be made by changing the range scale to shift the pipposition away from the center of the PPI. Parallax Error Improper use of the mechanical bearing cursor will introduce bearing errors. 
 22. 1960.  15. 
 Pulse compression is not generally used for meteorological applications be- cause peak power is not usually a limitation on system performance. Keeler and Frush,77 however, point out that pulse compression can be of benefit in some rapid-scanning applications. In situations where signals are very weak (such as for MST applications), pulse compression is used to increase system sensitivity by increasing the average power of the system. 
 Sanzullo, and L. Timmoneri, “Performance limitations and remedies in adaptive  spatial filtering with timing errors,” Signal Processing , Elsevier, vol. 82, no. 
 The use of integrated circuits in transceiver designs has enabled bold new module configurations, and hence phased array systems, to be envisioned. Since some of the more complex functions in the generic transceiver block diagram can be fabricated by using MMIC technology, the components that can be realized through the use of this technology can be employed to create system architectures that are difficult if not impossible to design with other, less integrated tech- nologies. The MMIC design approach utilizes active and passive devices that have been manufactured by using a single process. 
 %23 
 The input transformer Tissimilar totheone used forpentodes. Inorder torealize the ultimate noise-figure capabilities ofthe circuit, the Qofthe coils must bekept high. The circuit shown inFig. 
 No energy appears at port 4. The diodes act to either  pass or reflect the signals. When the impedance of the diodes is such as to pass the signals,  288INTRODUCTION TORADAR SYSTEMS <>--<.. 
 Radio enthusiasts are all too familiar with the diffi-  culties of using normal valves at very high frequencies.  A grid may be spaced about § inch away from an anode  in a broadcast valve, and the physical dimensions of the  electrodes are such that we do not need to worry about  them in the circuit constants, nor do we need to take  any special care about the inter-electrode capacity set up  through the electrode spacing. But when we want to  use such valves for the generation or reception of very  high frequencies we find that the capacity inside the  valve itself may have an appreciable relation to the  external capacities in the circuit itself, and unless we can  reduce or neutralize them we shall find that the valve  capacity stops the oscillation. 
 45. Van Vleck, J. H.: The Absorption of Microwaves by Uncondenscd Water Vapor, Phys. 
 9.17. The tolerance allowable inthesurface ofthereflector isabout ~+ ofawavelength. The larger sizes ofairborne reflectors, whether paraboloid orshaped cylindrical surfaces, thus farinstalled inastreamlined airplane arecon- siderably wider than high and areused forcircular scanning. 
 1931  A ship is equipped with radar. As antennae are used parabolic dishes with horn  radiators.   1936  The development of the Klystron by the technicians George F. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI.  AIRBORNE MTI  3.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 while reversing course, large crab angles when high winds are encountered, the need  to position ground track in relation to wind, nontypical operating situations, and opera - tions requirements for coverage while proceeding to and from the station. 
 Sensors 2019 ,19, 1920    (a) ( b)     (c) ( d)  Figure 9. Locally imaging results; ( a) FFT algorithm with 128 pulses; ( b) Relax algorithm with 128 pulses; ( c) APES algorithm with 128 pulses; ( d) KA-DBS algorithm with 128 pulses. Figure 10. 
 STAP’s ability to integrate clutter cancellation (temporal) and spatial interference  cancellation can be quite important to many radar systems whether they typically have to  deal with intentional jamming interference or unintentional (or casual) electromagnetic  interference (EMI). STAP gets away from cascaded solutions such as analog sidelobe  cancellers followed by digital DPCA and/or MTI filters—that do not generally create an  optimum interference cancellation solution. Optimal Adaptive Weights (McGuffin17). 
 Consider a conventional video MTI system, as shown in Figure 2.79. Because the  peak signal level is controlled by the linear-limiting amplifier, the peak excursion of  the phase-detector output is known, and the A/D converter is designed to cover this  excursion. If the A/D converter uses N bits and the phase-detector output is from −1 to  +1, the quantization interval is 2/(2N − 1). 
 RF.'ANewApproach toI.inearFiltering andPrediction Problems. TrailS.ASME.'/.Basic 1-.,1//11/.vo).X2.pp.l44\March.1960. 79.Schooler. 
 82 . 506 INTRODUCTION TO RADAR SYSTEMS  Still another factor which reduces the effectiveness of circular polarization in rain clutter  is the different reflection coefficients experienced· by the horizontal and vertical polarization  components on reflection from the surface of the land or the sea. This results in a change of  polarization and a degradation of the rain cancellation. 
 Datasets using traditional CNN model. Dataset Accuracy (%) D1 91.43 D2 87.49 D3 88.76 From Table 5, we can see that the traditional CNN models have low accuracy in the D2 and D3 datasets, but perform better with D1 dataset. This is expected, as the traditional CNN model we used have only 10 layers, which is a simple neural network. 
 V., and J. !I. Richter: Integrated Refractive Eflects Prediction System (IREPS), URSI  Commission F Open Symposiutn, Propagation in Non-Ionized Media, La Baule, France, Apr. 
 Searching a volume in space for an aircraft target with a narrow pencil beam would be  somewhat analogous to searching for a fly in a darkened auditorium with a flashlight. It must  he done with some care if the entire volume is to be covered uniformly and efficiently.  Examples of the common types of scanning patterns employed with pencil-beam antennas are  illustrated in Fig. 
 Off-nadir angle density, day 358  16~~~~~--~~~~~~--r-~~~~  14  12  .... 10  c::  ~ 8  Q)  CL 6  4  2  O~~~~w-~~ ~~~ u-~~~~ ~~~  0.10.30.50.70 .91.1 1.3  Off-nadar angle (degrees)  Figure 8-Typical distribution of altimeter-derived off-nadir  pointing.  180 strength, a temperature correction, the attitude/sea-state  correction, a long-term drift correction derived from on­ board calibrate mode data, and an initial offset selected  during ground test to convert gain control measurements  to aD (backscatter coefficient) from which wind speed  can be inferred. 
 This can be accom - plished with linear-FM ranging as in the HRWS waveform or M-of-N ranging used  by MRWS. These ambiguity resolution techniques dictate how the probability of  false alarm per range-doppler cell is computed. These calculations assume a noise- limited environment. 
 TION IS GIVEN BY   EA  S I NFNF " ¤ ¦¥³ µ´P    WHERE  A   PEAK PHASE RIPPLE  "   WAVEFORM INPUT BANDWIDTH  N   NUMBER OF CYCLES OF PHASE RIPPLE THE RESULTING OUTPUT DISTORTION PRODUCES RANGE SIDELOBES AT TIM ES oN  -" AND MAGNITUDE   LOG-A    RELATIVE TO THE MAIN BEAM OF THE TARGET RETURN !S AN EXAMPLE  GENERAT 
  P D     INVERSE CHI 
 The target signal in the auxiliary array which may result in nonnegligible steering of the auxiliaries toward the main-beam direction.33 6. The presence of clutter which, if not properly removed, may capture the adaptive system, giving rise to nulls along directions different from those of the jammers. 7. 
 Approximately 100 plywood antennas were constructed during the war. The production models that saw service showed nodeterioration over aperiod ofone year. 9“15. 
 Thefrequency ofaklystron isdetermined bytheresonant cavities. Whenallthe cavities aretunedtothesamefrequency, thegainofthetubeishigh,butthebandwidth is narrow, perhaps afraction ofonepercent. Thisisknownassynchronous tuning.Although maximum gainisobtained withallcavitiestunedtothesamefrequency, klystrons areoften operated withthenexttothelastcavity(thepenultimate cavity)tunedoutsidethepassband onthehigh-frequency side.Thegainisreduced byabout10dBinsodoing,buttheimproved electron bunching resultsingreaterefficiency andin15to25percentmoreoutputpower,7 Broadbanding ofamulticavity klystron maybeaccomplished inamannersomewhat analo­ goustothemethods usedforbroadbanding multistage IFamplifiers, thatis,bytuningthe individual cavitiestodifferent frequencies. 
 Ê*-/Ê 6 
 LOBE )&& ARRAY EMBEDDED IN THE ARRAY FACE 4HIS NOT ONLY PROVIDES EXCELLENT REGISTRA 
 AIS for SOLAS use is known as AIS Class A . There is a Class B system that is  designed for non-SOLAS use.28 This system uses the same VHF channels as Class A,  and the transmissions are necessarily compatible, but to avoid overloading the VHF  data link (VDL), Class B uses Carrier Sensing TDMA. This is aimed at confining  ch22.indd   23 12/17/07   3:02:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Any use is subject to the Terms of Use as given at the website. Civil Marine Radar.  CIVIL MARINE RADAR  22.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 degraded by clutter, and its tracking capability is compromised when targets are chang - ing course or passing close to other targets. AIS has reasonably good capability in  non-line-of-sight situations because of its lower frequency. 
 Next along theguide and ontheopposite side arethetwo ATIt tubes, oftheuntuned 1ow-Q type, spaced one half ofaguide wavelength apart. This gives abroadband characteristic. 1The resonant windows are made apart ofthe broad face ofthe waveguide. 
 LIMITED  PROVIDES MUCH GREATER TRACKING PRECISION IN THE LOW 
 Manufacturers are required to provide  effective manual and automatic anti-clutter functions and must specify the expected  degradation in rain at 4 mm and 16 mm per hour and for sea states 2 and 5, including  combinations of sea and rain clutter. Radars designed for conventional vessels need to operate with relative speeds  up to 100 kt. For high-speed craft, such as multi-hull fast ferries, the radars need to  operate with relative target speeds up to 140 kt. 
 Our electron beam thus traces the line, but the ‘flyback’  is blacked out for the return journey. Then +> second  later it starts a new journey in exactly the same place,  unless meanwhile we do anything to divert the spot into  another direction; and that is just what we do. We  put two plates, or a magnetic coil depending on the  associate apparatus, near the line of the beam, and wire  these plates or the coil to our radar transmitter and receiver. 
 TIVELY &OR A LINEAR ENVELOPE DETECTOR  THE SAMPLES HAVE A 2AYLEIGH DENSITY UNDER  (  AND A 2ICEAN DENSITY UNDER (  AND THE LIKELIHOOD RATIO DETECTOR REDUCES TO   IN II)!X4  ¤ ¦¥³ µ´q S   WHERE ) IS THE MODIFIED "ESSEL FUNCTION OF ZERO ORDER   R IS THE NOISE POWER  AND  !I IS  THE TARGET AMPLITUDE OF THE ITH PULSE AND IS PROPORTIONAL TO THE ANTENNA POWER PATTERN  &OR SMALL SIGNALS !I   R   THE DETECTOR REDUCES TO THE SQUARE 
 Howells, General Electric Co., Heavy Militmy Electronics Depart-  ment, Syracuse, N. Y.)  EXTRACTION OFINFORMATION ANDWAVEFORM DESIGN415 Figure11.9Three-dimensional plotoftheambiguity diagram forasinglerectangular pulse.(a)Contours forconstant dopppler frequency (velocity); (b)contours forconstant timedelay(range);(c)composite surface.(Courtesy S.Applebaum andP.W.Howells,GeneralElectricCo.,HeavyMilitaryElectronics Depart­ ment,Syracuse, N.Y.). 416 INTRODUCTION TO RADAR SYSTEMS  Figure 11.10 Two-dimensional arn-  higuity diagriirn for a single pi~lse of  sine wave. 
 LISHED THERE ARE PROGRAMS DEVELOPED IN HOUSE BY INDIVIDUAL RADAR COMPANIES  OR  AVAILABLE ON THE MARKET 4HE 2ADAR 7ORK 3TATION 273  IS AN EXAMPLE OF A DEVELOPED IN 
 27, 1934.  7. Vieweger, A. 
 The image of any target detected ahead ispainted on the PPI at its relative bearing and distance from the center ofthe PPI. As targets are detected in other directions, their images arepainted on the PPI at their relative bearings and distances from the centerof the PPI. Up to this point the discussion of how target information is displayed on the PPI has been limited to how the target images are painted, virtuallyinstantaneously, at their distances and relative bearings from the referenceship at the center of the PPI. 
 Making tlie same substitution of Eq. (14.29) into  tlic stir vcillaricc sad31 equation, Eq. (2.57). 
 For areas with surface temperatures between 10° and 30° Celsius and relative  humidities above 60% (i.e., the western Mediterranean, Red Sea, Indonesian Southwest  Pacific), surface-based subrefractive layers may develop during the night and early  morning hours. These layers are characteristically caused by advection of warm, moist  air over a relatively cooler and drier surface. While the N gradient is generally more  intense than that described above, the layer is often not as thick. 
 ING COEFFICIENT  V  USING KNOWN TARGET INFORMATION SUCH AS REPORTS FROM SHIPS AND COM 
  
 For thisreasonatwo-dimensional plotisoftenusedtoconveythesalientfeatures. Figure11.10is anexample ofthetwo-dimensional plotofthethree-dimensional ambiguity diagram corre­ sponding tothesinglepulseofFig.11.9c.Shading isusedtogiveanindication oftheregions inwhichIx(TR,14)12islarge(completely shadedareas),regionswhereIx12issmallbutnot zero(lightlyshadedareas),andregionswhere IX12iszero(noshading). Theplotforasingle pulseshowsasingleelliptically shapedregioninwhich 1X12islarge.Thisiswhatwouldhave beenexpected fromourprevious discussions sinceasinglemeasurement doesnotresullin ambiguity ifthethreshold ischosenproperly. 
 Ifthesignalcontains widelyspacedfrequency components the beamwillbespreadoveraconsiderable angular regionratherthanconfined toabeamwidth asdetermined fromdiffraction theory.Alternatively, fromthetimedelaypointofview,a narrowpulseimpressed attheinputoftheseries-fed arrayofFig.8.14,requires afinitetimeto. Figure 8.15 Scan angle 0, versus frequency. .fo corresponds to 0, = 0. 
 CALLY A SWEPT FREQUENCY TONE OR A NOISE INPUT THAT COVERS THE CHANNEL BANDWIDTH 4HE !$# SAMPLES OF ALL CHANNELS ARE COLLECTED SIMULTANEOUSLY AND COMPLEX WEIGHTS ARE CALCULATED FOR THE EQUALIZATION FILTERS THAT FORCE THE FREQUENCY RESPONSE OF EACH CHANNEL TO BE MATCHED /NCE THE CHANNEL IS EQUALIZED  A UNIQUE TIME DELAY IS IMPLEMENTED FOR  EACH BEAM TO BE FORMED !S MENTIONED EARLIER  THIS TIME DELAY CAN BE REALIZED EITHER  AS A PHASE SHIFT FOR A NARROWBAND SYSTEM OR AS A TIME DELAY FOR A WIDEBAND SYSTEM ! PHASE SHIFT CAN BE IMPLEMENTED WITH A COMPLEX MULTIPLY OR A #/2$)# OPERATION  BOTH OF WHICH WILL BE DESCRIBED LATER ! TIME DELAY CAN BE IMPLEMENTED WITH A &)2 FILTER THAT IMPOSES A LINEARLY CHANGING PHASE SHIFT OVER FREQUENCY ON THE SIGNAL /NCE THE TIME DELAY IS REALIZED IN EACH CHANNEL  THE APPROPRIATE COMPLEX TIME 
 AMPLITUDE  CONVERTER  WHICH IS A LOOKUP TABLE THAT PRODUCES A  K 
 The most common SAW materials are quartz and lithium niobate. Other Passive Linear-FM Devices. Table 10.2 summarizes the general characteristics of several other passive devices that are used for linear-FMINPUTINPUTARRAYDELAYMEDIUMOUTPUTARRAY ACOUSTICABSORBER OUTPUT GROUND PLANE ACOUSTIC ABSORBERBRNDWIDTH (MHz) . 
 Such seems to be the case for satellite surveillance  where the same frequency (UHF) seems desirable for both search and track, as in the  AN/FPS-85.  The unique characteristics of an array antenna offer the radar systems designer capabili­ ties not available with other techniques. As with any other device, the array will see major  application when it can perform some radar function cheaper than any other anlcnna type or  when it can do something not practical by other means. 
 FREQUENCY NOISE SPECTRUM SIMI 
 QUENCIES  MESSAGES ARE SENT TO ONE OR MORE MISSILES ON THE FLY TO THE TARGETS /BVIOUSLY  ALL THE RANDOM FREQUENCY DIVERSITY  SPREAD SPECTRUM  AND ENCRYPTION NECESSARY FOR ROBUST COMMUNICATION SHOULD BE INCORPORATED INTO THE MESSAGE  %ACH MISSILE MAY  ANSWER BACK AT A KNOWN BUT RANDOMIZED OFFSET FREQUENCY AND TIME WITH IMAGE OR HOUSEKEEPING DATA !GAIN A WAVEFORM AS ROBUST AS POSSIBLE IS USED  BUT SINCE THE BASE 
 Lloyd: Virtual Path Tracing for HF Radar Including an Ionospheric Model, Naval Res. Lab. Memo. 
 Ifthesinglescanprobability ofdetection forasurveil­ lanceradarisPd,theprobability ofdetecting atargetatleastonceduringNscansiscalledthe cumulative probability ofdetection, andmaybewritten (2.56) (2.57)Thevariation ofPdwithrangemighthavetobetakenintoaccount whencomputing Pc.The variation ofrangebasedonthecumulative probability ofdetection canbeasthethirdpower ratherthanthemoreusualfourthpowervariation basedonthesinglescanprobability. 59 Thecumulative probability hassometimes beenproposed asameasure ofthedetectabi­ lityofaradarratherthanthesingle-scan probability ofdetection, whichismoreconservative. Inpractice theuseofthecumulative probability isnoteasytoapply.Furthermore, radar operators donotusuallyusesuchacriterion forreporting detections. 
 (ed.): "Radar Handbook," McGraw-Hill Book Company, New York, 1970. 17. Ewing, E. 
 The four look directions with respect to the given current ﬁeld are shown in Figure 11. The red arrows represent radar look directions. The xaxis of the current ﬁeld and wind direction are indicated by black arrows. 
 An example of how limiting the dynamic range adjusts the residue is shown in the  MTI PPI photographs shown in Figure 2.62. The range rings are at 5-mi intervals.   FIGURE 2.62  Effect of limiters: ( a) 18 dB improvement factor, 20 dB input dynamic range, and   (b) 18 dB improvement factor, 14 dB input dynamic range ch02.indd   59 12/20/07   1:45:15 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 SIS  AND BE MORE DIFFICULT TO REMOVE AFTER THAT PRIMARY PROCESS ING 4YPICALLY  THERE ARE  OPTIONAL  PROCESSING ALGORITHMS AVAILABLE TO REMOVE IMPULSIVE NOISE ORIGINATING FROM LIGHTNING  TRANSIENT ECHOES FROM METEORS  AND FIELD 
 8.24  Maximum-Likelihood Ap proaches  ......................  8.38  8.4 Multisensor Integration  ...........................................  8.40  Colocated Radar Integration  .............................. 
 3  In addition to being used as the power tube for high-power radar systems, thc traveling-  wave tube has also been employed, at lower power levels, as the driver for high-power tube>  (such as the crossed-field amplifier), and in phased array radars which use many tubes to  achieve the desired high-power levels.  6.5 HYBRID LINEAR-BEAM AMPLIFIER  By combining the advantages of the klystron and the traveling-wave tube into a sitlgle dcvice it  is possible to obtain a high-power amplifier with a bandwidth, efficiency, and gain flatnesb  better than can be obtained with either the usual klystron or TWT.' One such device is thc  Varian Twystron (a trade nam~), which is a hybrid consisting of a millticavity klystron inpt~t  section coupled to an extended interaction traveling-wave output section. The limitation to the  bandwidth ofa klystron is generally the output cavity. 
 64.Bego....ich.N.A.:Frequency Scanning. chap.2of"Microwave Scanning Antennas. Vol.III,"R.C. 
  OR SPURIOUS 
 STATE REPLACE 
 /ÊÊ  /Ê 
 Figure 5is the interferometric phase distribution of the complex image of two channels after processing. According to the comparative study on Figure 5a–d, the accuracy of scattering point in obtaining interferometric phase is higher and broader for the proposed approach comparing with that of the independent single-channel processing imaging approach. Figure 5. 
 Also the phases oftheir echo signals are completely independent. Under these two conditions, the vector R2has aprobability distribution like that of statistical noise-that is,theend ofthevector hasa Gaussian distribution about thepoint O’. Thepulse-to-pulse change rlikewise has aGaussian distribution. 
 R., R. J. Serafin, D. 
 TERN WILL CONTAIN NULLS STEERED IN THE DIRECTION OF THE MAIN 
 The CATHODE-RAY TUBE (CRT), illustrated in ﬁgure 1.17, is the heart of the indicator. The CRT face or screen, which is coated with a ﬁlm ofphosphorescent material, is the PPI. The ELECTRON GUN at the oppositeend of the tube (see ﬁgure 1.18) emits a very narrow beam of electronswhich impinges upon the center of the PPI unless deﬂected by electrostaticor electromagnetic means. 
 TION  A RADAR CAN ALSO FIND THE RELATIVE VELOCITY OF A TARGET EITHER BY DETERMINING THE RATE OF CHANGE OF THE RANGE MEASUREMENT WITH TIME OR BY EXTRACTING THE RADIAL VELOCITY FROM THE DOPPLER FREQUENCY SHIFT OF THE ECHO SIGNAL )F THE LOCATION OF A MOVING TARGET IS MEASURED OVER A PERIOD OF TIME  THE TRACK  OR TRAJECTORY  OF THE TARGET CAN BE FOUND FROM WHICH THE ABSOLUTE VELOCITY OF THE TARGET AND ITS DIRECTION OF TRAVEL CAN BE DETERMINED AND A PREDICTION CAN BE MADE AS TO ITS FUTURE LOCATION 0ROPERLY DESIGNED RADARS CAN DETERMINE THE SIZE AND SHAPE OF A TARGET AND MIGHT EVEN BE ABLE TO RECOGNIZE ONE TYPE OR CLASS OF TARGET FROM ANOTHER "ASIC 0ARTS OF A 2ADAR  &IGURE  IS A VERY ELEMENTARY BASIC BLOCK DIAGRAM  SHOWING THE SUBSYSTEMS USUALLY FOUND IN A RADAR 4HE  TRANSMITTER  WHICH IS SHOWN HERE  AS A POWER AMPLIFIER  GENERATES A SUITABLE WAVEFORM FOR THE PARTICULAR JOB THE RADAR IS TO PERFORM )T MIGHT HAVE AN AVERAGE POWER AS SMALL AS MILLIWATTS OR AS LARGE AS MEGA 
 9311-946,  Dec. 1 and 15, 1946.  18. 
 A: wavemeter; B: tuning control; C: attenuator rate control; D: switch unit; E: indicator unit [ 20]. Figure 4.28. Engineer ’s compartment. 
 274INTRODUCTION TORADAR SYSTEMS 18.Paramonov, A.A.:Influence ofPrecipitation ontheElectrical Properties ofWireMeshSurfaces, Radiotekhnika, vol.11,no.9,pp.12-20,1956. 19.Hannan, P.W.:Microwave Antennas Derived fromtheCassegrain Telescope, IRETrails.,vol.AP-9, pp.140-153, March,1961. 20.Morgan, S.P.:SomeExamples ofGeneralized Cassegrainian andGregorian Antennas, IEEETrulls., vol.AP-12,pp.685-691, November, 1964. 
 Ikard, t'. I.. I. 
 Real value coefficients typically used in I/Q generation provide fil - ter responses symmetrical about zero frequency. Correction of IF filter frequency  response errors will, in general, require asymmetric frequency correction that can  only be provided at baseband using complex coefficients. The degree to which these multiple receiver channels must track depends on the  specific system requirements. 
 WAVE PROPAGATION 4HIS RAISES THE POSSIBILITY OF EXPLOITING MULTIPLE FREQUENCIES MORE EFFECTIVELY  SO AS TO EXTRACT ADDITIONAL TARGET AND SEA 
 Rey, E. Thouvenot, and J. Verron, “AltiKa:  a Ka-band altimetery payload and system for operational altimetry during the GMES period,”  Sensors , vol. 
 4.7). In-band spurious noise may also be de- graded by the source of RF drive (Sec. 4.3). 
 Platform location and orientation must be sensed, and perhaps stabilized, and provided to the radar computer. Some of these quantities are also required for platform navigation and therefore may be available from the navigation gyros. 20.3 HEIGHT ACCURACY PERFORMANCE LIMITATIONS The accuracy of the measurement of target height with a radar is conveniently expressed in terms of the root-mean-square error (rmse), i.e., the square root of the expected value of the square of the difference between the estimated target height and the actual target height. 
 There were 112 final power output modules  arranged in two groups of 56. Each module (Figure 11.24) produced 2500 W peak and  50 W average for a 60-µs pulse width at a 2% duty cycle. Drive power for the two FIGURE 11.23  PA VE PAWSUHF T/R module consists of transmit module and receive  module in a nested configuration of cast aluminum housings ( Photograph courtesy of  Raytheon Company ) ch11.indd   32 12/17/07   2:25:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 LIMITED DISTRIBUTED CLUTTER ARE SHOWN IN &IGURE  .OTE THAT FOR  .     LESS THAT  OF THE HARD 
 PULSE STAGGER )N THE PULSED OSCILLATOR SYSTEM  SHOWN IN &IGURE   PULSE 
 105, Sclirank. 11. I:.. 
 Thus R5Q can de- note the range for 0.5 (i.e., 50 percent) probability of detection and some sepa- rately specified false-alarm probability. If the target cross section a fluctuates, this fluctuation will alter the signal- plus-noise statistics. As mentioned in Sec. 
   3EPTEMBER   7 + +AHN  h)MPEDANCE 
 and Y.Z. revised the manuscript. All authors read and approved the ﬁnal version of the manuscript. 
 Crombic: Sea Backscatter at HF: Interprcta-  tion and litilization of the Echo. Proc. IEEE, vol. 
 ( Photograph courtesy of  Raytheon Company ) ch11.indd   26 12/17/07   2:25:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 
 LIMITED FUNCTION )N MOST CASES  NEAR IDENTICAL ANTENNA ARE USED  AND IF THESE ARE SPACED SUFFICIENTLY FAR FROM THE GROUND SURFACE  THEN  S AFT    SART  )N THE CASE OF ANTEN 
 (ed.): "Microwave Receivers," MIT Radiation Laboratory Series, vol. 23,  McGraw-Hill Book Company, New York, 1948.  5. 
 and two glass-to-metal windows to seal in the gas at low pressure. A noble gas like argon in the  TR tube has a low breakdown voltage, and offers good receiver protection and relatively long  life. Pure-argon-filled tubes, however, have relatively long deionization times and are not  suitable for short-range applications. 
 A significant irnprovetnent in power, efficiency, stability, and life over the  conventional nlag~ietrori is obtained wlieri the straps are removed and the n mode is coritrolled  by coupling alternate resonators to a cavity surrounding the anode. This is known as a coa.uial  ~rtn~g~tc~trotr since the stabilizing cavity surrounds the conventional resonators. as sketched in  RADAR TRANSMITTERS 193 ®Figure6.1Cross-sectional sketchoftheclassical cavitymagnetron illustrating component parts. 
  
 28•29 If the target is in motion and the beat signal contains a component due to the!  doppler frequency shift, the range frequency can be extracted, as before, if the average  frequency is measured. To extract the doppler frequency, the modulation waveform must have  equal upsweep and downsweep time intervals.  The FM-CW radar principle was known and used at about the same time as pulse radar,  although the early development of these two radar techniques seemed to be relatively indepen­ dent of each other. 
 Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters.  SOLID-STATE TRANSMITTERS  11.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 (MOCVD) fabrication techniques to achieve the high performance characteristics.  These are capital-intensive semiconductor processing steps that are required in  order to achieve the high quality channel characteristics that define a microwave or   millimeter-wave power transistor. 
 TIME $30 SYSTEMS WERE DESIGNED &0'!S ARE INTEGRATED CIRCUITS THAT CONSIST OF A LARGE ARRAY OF CONFIGURABLE LOGIC ELEMENTS THAT ARE CONNECTED BY A PROGRAMMABLE INTERCONNECT STRUCTURE !T THE TIME OF THIS WRITING  &0'!S CAN ALSO INCORPORATE HUNDREDS OF MULTIPLIERS THAT CAN BE CLOCKED AT RATES UP TO A HALF BILLION OPERATIONS PER SECOND  AND MEMORY BLOCKS  MICROPROCESSORS  AND SERIAL COMMUNICATION LINKS THAT CAN SUPPORT MULTIGIGABIT 
 However, it introduces problems of its own. Cross-polarization lobes are produced by the  offset geometry, which may seriously deteriorate the radar system performance.1• 17 Also, it is  usually more difficult to properly support and to scan an offset-feed antenna than a circular  paraboloid with rear feed.  f/D ratio. 
 The disk is mounted on bearings inside the vacuum (developed first for rotating- anode x-ray tubes) and is magnetically coupled to a shaft outside the vacuum. At 1800 r/min, a tube with 10 cavities tunes across the band 300 times per sec- ond. By ensuring that the modulator pulse rate is not synchronous with the tuning rate, the transmitted frequency will vary from pulse to pulse in a regular pattern as the PRF beats with the tuning rate. 
 Ithasalsobeensuggested 54thatpolarization agilitycanreducetheglinterror.Sincethe individual echoesfromthevariousscattering centersthatmakeupacomplex targetarelikely tobesensitive tothepolarization oftheincident radarsignal,achangeinthepolarization can possibly resultinanindependent measure oftheapparent targetdirection. Byobserving the targetwithavariable polarization producing independent measurements, theangleerrordue toglintisaveraged andtheeffectofthelargeglinterrorsisreduced. Experimental measure­ mentswithanX-band,conical-scan, pulsedoppler radartracking anM-48 t~katapproxi­ mately500mrangereduced theangular tracking errorbyaboutone-half. 
 IEEE, vol. 67, no. 11, pp. 
 FICIENTS ONLY AT EVEN NUMBERS OF DELAYS  SO IT IS REALIZED WITH DOUBLE DELAYS ONLY 4HE ARCHITECTURE CAN THEN BE FURTHER SIMPLIFIED BY MOVING THE DECIMATION AHEAD OF  THE S   DELAYS  AS SHOWN IN &IGURE  B 4HIS CHANGES EACH DOUBLE DELAY TO A SINGLE  DELAY AT THE LOWER CLOCK RATE AT WHICH THE FILTER COMPUTATIONS ARE NOW MORE EFFICIENTLY CLOCKED /PTIONALLY  THE NEGATION OF ALTERNATE SAMPLES AT THE OUTPUT CAN NOW BE RELO 
 Spetner, “Two statistical models for radar return,” IRE Trans. , vol. AP-8,   pp. 
 A., Y. T. Lin, and L. 
 At higher altitudes, more looks are gathered to partially offset the  degraded resolution. The radar’s noise-equivalent s  0 ranges from ∼ −25 dB at low  altitude, to ∼ −8 dB at 4000 km altitude. In contrast to the scheme used on Magellan ,  smaller angles of incidence and lower bandwidth are used for the higher altitudes. 
  AND SHORT 
 The optimum value of m for a constant echo signal is  shown in fig. 10.8. (Similar results are available for fluctuating targets. 
 Because ofthe effects ofpresentation time and pulse width ~ByR.D.O’Neal andJ,M.Wolf.. SEC, 152] NEED FOR SYSTEM TESTING 591 (Sees. 210 and 211), such test signals aregenerally not equal toSmirs but differ from itbyaconstant ratio, The ratio between pulse power and the power ofsuch atest signal, P/ST,expressed indecibels, iscalled the “radar performance figure” and isasuitable measure ofthe ability of thesystem toseeradar targets. 
 NOISE SPECTRAL DENSITY 4!",%  )NTEGRATION OF THE 0HASE 
 Some method of signal recognition or  pattern recognition must be applied to be able to correctly estimate the type of target. This can  be just as important a part of target classification as the sensor itself.  Target track history. 
 Then a filter or gate is set to excise main-beam clutter returns in that area. The amount of range-doppler space excised by this procedure can be as high as 8 percent.45 Time Synchronization. Time synchronization is required between the bistatic transmitter and receiver for range measurement. 
 9.3and 11.1) that energy may bepropagated inthe space between flat parallel sheets of metal. Inthis and thetwo sections following weshall discuss electrical scanners inwhich curved parallel plates areused. Ineach scanner the plates are straight along one side; the microwaves escape from the straight gap between theplates onthis side and then illuminate apara- bolic reflector. 
      )     %  #"& )  *. 
 WAVE BACKSCATTER BEHAVES IN MUCH THE SAME MANNER AS BACKSCATTER AT THE LOWER MICROWAVE FREQUENCIES 4HIS WAS SUGGESTED BY THE + 
 The function of  the Ideal Observer is to minimize the total probability of error. It accomplishes this by  adjusting the threshold, which in turn affects both the false alarm and the miss probabilities.  The dependence of the two errors upon one another is probably the chief limitation of the  Ideal Observer as a radar detection criterion. 
 Sci.) 2017 ,60, 060303. [ CrossRef ] 10. Yin, W.; Ding, Z.; Lu, X.; Zhu, Y. 
 30. L. Bömer and M. 
 During reception, the transmitter is off and neither the TR nor the ATR is fired. The open  circuit of the ATR, being a quarter wave from the transmission line, appears as a short circuit  across the line. Since this short circuit is located a quarter wave from the receiver branch-line,  the transmitter is effectively disconnected from the line and the echo signal power is directed to  the receiver. 
 108. V . Kudryavtsev, D. 
 OBSERVING 3!2S IS ON THE ORDER OF  -BITS .EWER DESIGNS CLAIM UP TO  -BITS 3INCE THE  -AGELLAN OBJECTIVE WAS TO IMAGE A SUBSTANTIAL POR 
 The GPR image of a target is very different from its optical image because the  wavelengths of the illuminating radiation are similar in dimension to the target. This  results in a much lower definition in the GPR image and one that is highly dependent  on the propagation characteristics of the ground. The beam pattern of the antenna is  widely spread in the dielectric and this degrades the spatial resolution of the image,  unless corrected. 
 Usingthecalculus ofvariations, Mallinckrodt andSollenberger3showthattheFourier transform 5g(f)oftheoptimum gatingfunction whichminimizes thetime-delay error [Eq.(11.8)]isgiven,exceptforanarbitrary constant factor,by (11.9) r / ::Ja. ~ ::Ja L Q) > Q) u Q) Cl:: -/l/-----~/_E-----------____=,....__:::__.MR=TR-lQ Figure11.3Effectofnoisen{t}inshiftingtheapparent zerocrossing oftheoutputso(TR-To)ofthe gatingreceiverofFig.11.2.. 404 1NTRODUCTiON TO RADAR SYSTEMS  where S(f) and N,(f) are the Fourier transforms of the input signal s(r - To) and the inpltt  noise n(t), respectively. 
 SEC. 5.4] CLASS OF SYSTEMS CONSIDERED 131 Such, then, isthe information potentially available tothe receiver ofaradar set. The amount ofthis information, which varies with set type, may beenormous, and use isseldom made ofallofit. 
 K. Barton, CW and Doppler Radars,   Section VI-3, Vol. 7, Norwood, MA: Artech House, Inc., 1978, pp. 
 For a long time, it was the transmitter of  choice for use in the civil marine radar, one of the most widely used radars, as briefly  discussed next. Civil Marine Radar Magnetrons .27 The magnetron has been well-suited for  application in civil marine radars used on small pleasure boats or large commercial  ships. Its success has been due in part to the radar needing only small transmitter  power, and the radar does not require doppler processing to separate moving targets  from large fixed clutter echoes. 
 6.) Moving Window. The moving window in Fig. 8.3a performs a running sum of n pulses in each range cell; Sf = S1-.i 4- X1 - *,--„ (8.5) where S1 is the sum at the /th pulse of the last n pulses and Jc1 is the /th pulse. 
 Spaulding, A. D.: The Electromagnetic Interference Environment: Man-Made Noise, pt. 1: Est~ma  tion of Business, Residential and Rural Areas, Office of Telecommltnicatiotls, U.S. 
 Hthereexists, however, inherent instabilities intheradarsystemtherecanresultnoiseliketime-sidelobes. EXTRACTION OF INFORMATION AND WAVEFORM DESIGN 433  accomparlying the pulse-compression wavefor-m. Such system instabilities might be caused by  noise on local oscillators, noise on transmitter power supplies, transmitter time jitter, and  transmitter tube noise. 
 F.: MTI Weightings, IEEE Trans., vol. AES-10, pp. 153-155, January, 1974. 
 FED REFLECTOR $URING THE S AND S  PHASE SHIFTER AND 42 MODULE TECHNOLOGY GREATLY MATURED AND %3! COSTS DROPPED DRAMATICALLY 4HESE ADVANCES HAVE RESULTED IN INCREASED INTER 
 "ASED -EASUREMENTS OF 3NOW 
 Taking example for linear frequency modulation (LFM) signal, the echo signal of the target P in ArcSAR system is shown as: S(θ,tr)=δprect⎭parenleftBig⎭parenleftBig tr−2Rp/c⎭parenrightBig /Tp⎭parenrightBig ·rect((θ−ϕ)/θbw) exp⎭parenleftbigg jπKr⎭parenleftBig tr−2Rp/c⎭parenrightBig2⎭parenrightbigg ·exp⎭parenleftBig −j4πfcRp/c⎭parenrightBig (3) 132. Sensors 2019 ,19, 2921 whereδpis the backscattering coe ﬃcient, tris the fast time of the ArcSAR system, crepresents the speed of light, Tpstands for the signal pulse width, θbwis the antenna beam width, Krrepresents the linear frequency modulation (LFM) rate, and fcis the center frequency. Rprepresents the distance between target P and the APC, which can be expressed as: Rp=⎭radicalbigg R2 0+r2−2r⎭radicalBig R2 0−h2cos(θ−ϕ) (4) We perform pulse compression of S(θ,tr) in the frequency domain on the range direction. 
 Theimportant parameters affecting rangearethetotaltransmitted energyfiE,.thetransmitting gainG.theeffective receiving apertureAnandthereceiver noise figureFn. 2.10PULSE nEPETITION FI~EQLlENCY ANDRANGI£ AMBIGUITIES Thepulserepetition frequency (prr)isdetermined primarily bythemaximum rangeatwhich targetsarcexpected. Iftheprfismadetoohigh.thelikelihood ofobtaining targetechoesfrom thewrongpulsetransmission isincreased. 
 S n 4HIS PRODUCED A REVOLUTION IN THINKING ABOUT THE ORIGINS OF  SEA CLUTTER BECAUSE IT INVOLVED THE SEA WAVE  SPECTRUM  THUS FORGING A LINK BETWEEN  CLUTTER PHYSICS AND OCEANOGRAPHY IN WHAT BECAME THE FIELD OF  RADIO OCEANOGRAPHY  (OWEVER  FUNDAMENTAL CONCEPTUAL PROBLEMS IN APPLYING THE "RAGG HYPOTHESIS IN MICROWAVE SCATTERING  ALONG WITH ITS INABILITY TO ADDRESS SIGNIFICANT ASPECTS OF MEA 
  
 Refocused images of ship05 sub-image. ( a) Sub-image of ship05; ( b) Refocused image with the DCT method; ( c) Refocused image with the PGA method; ( d) Refocused image with the proposed method.      (a) (b)       (c) (d)  Figure 17. 
    
 It should be kept in mind that Eq. 2.34 for the optimum weights will yield a dif - ferent result for each different target doppler shift, so that a large number of parallel  filters would be needed to approximate the optimum performance even when the clutter  characteristics are known exactly. As an example, the response of the optimum filter  designed for one particular target doppler frequency labeled as point A in Figure 2.25  is shown in a broken line. 
 Asaraingaugeitisquiteuseful tothehydrologist indetermining theamountofwaterfallingintoawatershed duringagiven periodoftime.Radarhasbeenusedextensively forthestudyofthunderstorms, squalllines, tornadoes, hurricanes, andincloud-physics research. Notonlyisradarusefulasameansof studying thebasicproperties ofthesephenomena, butitmayalsobeusedforgathering the information neededforpredicting thecourseoftheweather. Hurricane tracking andtornado warning areexamples ofapplications inwhichradarhasproveditsworthinthesavingoflife andproperty. 
 Oceanic  Technol. , vol. 17, pp. 
 Where we have a display of blips  . 44 HOW RADAR WORKS  along a straight-line time-base noise shows up as a  shimmering effect along the whole time-base, having  the appearance of a rapid series of random deflections;  in many radar systems the colour of fluorescence on the  tube-end is green, so this noise looks for all the world  like a shimmering layer of grass, and in radar colloquy.  is, in fact, known as ‘grass.’ As the gain of the receiver  is turned up the background hiss increases, and the  layer of grass along the time~base line deepens. 
 ING ! COMMON METHOD OF FREQUENCY MEASUREMENT IS TO USE A SCANNING SUPERHETERO 
 Warner, “Radar cross-sections of terrain near vertical inci - dence at 415 Mc, 3800 Mc, and extension of analysis to X band,” University of New Mexico,  Eng. Exp. Sta., TR EE-21, Albuquerque, 1959. 
  %UROPE  
 First sidelobes of from 40  to 50 dB below the main beam may be possible with the proper aperture illuminations and the  proper care in implementation. A high-gain antenna is usually necessary to achieve such low  sidelobes. (When referred to the radiation from an isotropic antenna, the peak sidelobes from a  low-sidelobe antenna might be approximately 10 to 15 dB below the isotropic level.) The  RADAR ANTENNAS 227 bytheantenna totheincident wave.ThegainGandthecf[ectivcarea l1..ofalosslessantellna arerelatedby .4rr11"(J= ---r-A(7.9) whereA=wavelength A=physical areaofantenna fla=antenna aperture erticiency Polarization. 
 I). K.: A Target 'l'rajcctory Noise Model for Kalman Trackers. IEEE Tratrs., vol. 
 Thus, discrimination requires a parame - ter in addition to the target RCS. The available parameter is target radial velocity. Birds  typically fly at 40 knots or less, whereas targets of concern usually have airspeeds of  100 knots or more. 
 BEAM $ISPLACED 0HASE 
 SEC.9.14] SCHWARZSCHILD ANTENNA297 arms rotate at240 rpm, asdothe four arms Hwhich support the feed horns. They remain inthe angular relation shown. Between the two sets ofarms isastationary ring with a105° window through which energy may pass into whichever feed horn isopposite the feeding edge ofthe folded horn. 
 U.S.PatentNo.3,797.017, Mar.12,1974. 26.flouts.R.C..andD.W.Burlage: DesignProcedure forImproving theUsableBandwidth ofanMTI HadarSignalProcessor. IEEECan(erellc£' Record1976International Conference 011Acoustics, Speed,. 
 Knittel (eds.), Artech House, Dedham.  Mass .. 1972, pp. 
 7, pp. 62 65,  April, 1964.  107. 
 both in theory  and in practice. Tile backscatter from land is significantly greater than from sea except in the  vicinity of near vertical incidence. Therefore. 
 CAL METHOD USED TO IMPROVE THIS FILTER RESPONSE IS TO INCREASE THE FILTER ORDER BY ADDING MORE STAGES &IGURE  SHOWS A THREE 
 Another is that the weight of the transmitter is now added to that of the . RADAR TRANSMITTERS 219  ,.,./,:,•.·.- ', I ,\ ,,,,,,'  2-~j) ~·)-; >1 :-~~.u.;t~-:·- } f.·, ;~·.~ 1).t~)r.~~:.~--·,; H:  ' < .:. ii,, •. 
 Inprinciple. the pattern isindependent ofbeamdirection. Mostoftheworkonconformal arrayshasbeenwiththecylinder. 
 For example, it is not clear whether the actual effect of a spatially varying atmospheric stratiﬁcation on the surface wave ﬁeld is always adequately represented by the effect of the proposed equivalent variations of Vxand Vy. Furthermore, our surface wave model does not yet account for effects like wave breaking [ 29]o r feedback between the surface roughness and wind stress [ 30]. The inclusion of such effects may lead to changes in the simulated radar signatures. 
 290INTRODUCTION TORADAR SYSTEMS inthehybridcircuit.Theswitched-line phaseshifterhasthegreatest insertion loss,butitsloss doesnotvarywiththeamount ofphaseshiftasitdoesintheothertwotypesofcircuits. Diodephaseshiftershavebeenbuiltinpractically alltransmission linemedia,including waveguide, coaxandstripline.Microstrip isusefulformedium-power devicesbecauseofthe easeofmanufacture, circuitreproducibility anditsreduced size,weight,andproduction costs. Thediodechipsmaybemounted directlyonthesubstrate without theparasitic reactances of thediodepackages. 
 1.4istreated. Inaddition, consideration isgiven totheproblem ofsupplying primary power inaform suitable forusewith aradar set; this isespecially difficult and important inthecase ofairborne radar. 1.4. 
 The stack ofREFLECTORANTENNA MOVING FEEDLINEARRAYHORIZONTALFANBEAMS RECEIVER COSECANTSQUAREDBEAM20 ANTENNA TRANSMITTER ROTATION (e)(f) . receive beams may be formed in a number of ways from the line array. One tech- nique is the Butler matrix, an RF feed analog of the discrete Fourier transform. 
 Ê/,    2ANGE TRACKING IS ACCOMPLISHED BY CONTINUOUSLY MEASURING THE TIME DELAY BETWEEN  THE TRANSMISSION OF AN 2& PULSE AND THE ECHO SIGNAL RETURNED FROM THE TARGET  AND CON 
 This property  characterizes most of the polarimetry literature, at least in remote sensing applications,  and is reflected in these paragraphs. (The principal exception to this rule is Faraday  rotation, which may be a significant factor for longer wavelength systems, such as P  band and to a lesser extent L band.) For irrotational propagation, the portion of the backscattered field captured by the  radar is determined by the polarization vector of the receiving antenna, [ E R]. The sig - nal voltage vrec entering the system may be written in vector-matrix form as  v E EE EHR VR HB VB rec=   (18.15) This is the starting point for SAR quadrature polarimetry. 
 The result is that AEW systems have  been developed at UHF, L band, and S band frequencies. Airborne MTI radar systems have also been utilized to acquire and track targets in  interceptor fire control systems. In this application, the systems have to discriminate  against clutter only in the vicinity of a prescribed target. 
 http://elib.dlr.de/43957/ 29. http://www.gmes.info/TABLE 18.2  Synthetic Aperture Radars (Earth-viewing) ( Continued ) ch18.indd   7 12/19/07   5:13:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 56. Andreone. V. 
 Proc.IEEE,vol.64,pp.6J9-652. May.1976. 22.Bristol,T.W.:SurfaceAcoustic WaveDevices-Technology andApplications, IEEE1976WESCON Professional Program. 
 (12.15) or Eq. (12.16) after suitable analysis. This analy- sis assumes that only doppler fading con- tributes to independence but motion from one cell to another also adds independent samples. 
 15.4] THE RANGE EQUATION 595 notunduly difficult tofitbybeam-shaping. Even greater coverage both inrange and height was known tobedesirable, but itappeared tobe attainable only byexcessive antenna size orbyanexcessive multiplicity ofseparate radar beams, each with itsown transmitter and receiver system. Amicrowave setwith the coverage shown inFig. 
 11.9a. The contour for zero velocity is triangular in shape and represents the  autocorrelation function of a rectangular pulse such as would be predicted from Eq. ( 11.52). 
 BASED DUCTING IS ASSOCI 
 AES-16, pp. 783–799, 1980. 116. 
 DETECTION INTEGRATION WITH FREQUENCY AGILITY #LUTTER FALSE ALARMS ARE SUP 
 (In the conical scan tracker,  only one squinted beam is scanned.) In conopulse, the sum and difference signals received in  the two squinted beams are extracted in a manner similar to that of the conventional monopulse  system. Two-coordinate angle information is obtained by scanning the beams about the bore­ sight axis similar to the extraction of azimuth and elevation angle information in the conical·  scan tracker. Amplitude fluctuations of the target echo signal do not in principle degrade the  tracking accuracy as in the conical-scan tracker because a difference signal is extracted from  the simultaneous outputs of the two squinted beams. 
 J.: Navy Improves Accuracy, Detection Range of Space Surveillance Chain, Aviario11 Week,  Aug. 16. 1965. 
 36.)NUMBER OF TIMES TWO TARGETS WEREDETECTED OUT OF 40 OPPORTUNITIES Thresholding technique All reference cells Reference cells with minimum mean valueTarget separation 1.5 2.0 2.5 3.0 1.5 2.0 2.5 3.010 0.0 0.0 0.04 0.0 0.0 0.10 0.18 0.22S/N of target no. 2 13 0.04 0.22 0.24 0.24 0.0 0.32 0.58 0.6620 0.0 0.54 0.94 0.88 0.00 0.44 0.98 0.9830 0.00 0.14 0.62 0.92 0.0 0.12 0.46 0.8240 0.00 0.10 0.32 0.76 0.02 0.04 0.28 0.74 . varying between one-fourth and three-fourths of a pulse width, depending on the relative phase difference between the two targets. 
 METHOD OF MOMENTS v  ./3# 4ECH $OC       2 7 "OGLE AND $ " 4RIZNA  h3MALL BOAT RADAR CROSS SECTIONS v .AVAL 2ES ,AB -EMO 2EPT     *ULY   2 $INGER  % .ELSON  3 !NDERSON  & %ARL  AND - 4YLER  h(IGH FREQUENCY RADAR CROSS SECTION  MEASUREMENTS OF SURROGATE GO 
 H.: "The Radio Noise Spectrum," Harvard University Press, Cambridge, Mass., 1960.  50. Greene, J.C., and M. 
 The Jindalee radar was designed with the facility to apply a num - ber of amplitude notches within the sweep, thereby enabling the radar to sweep at  zero amplitude across narrow-band users in the same frequency band without causing  interference. Another class of variations involves departing from a linear frequency  modulation. By varying the frequency-time characteristic of the waveform, range side- lobes can be reduced and spectral leakage can be controlled. 
 Schlerer (ed.), MTI Radar , Norwood, MA: Artech House, Inc., 1978.  7. F. 
 and G. R. Cooper: Measurement of Distributed Targets with the Random Signal  Radar, iEEE Trans., vol. 
 FACE AND METAL 
 Inaturn the gyro rotor tends toalign itself with the resultant ofthe true gravity and the centrifugal force caused bythe acceleration intheturn, instead ofwith true gravity alone. This can be minimized oreliminated byusing atwo-speed erection mechanism, orby employing anelectromagnetic clutch tothrow out the erection system entirely inturns. Continuing thegeneral classification previously referred to,stabilizers may befurther typed asstable-base, roll, orline-of-sight, depending on thestabilization compensation afforded. 
 POLARIZED CONDITION &)'52%     #ALCULATED RMS MULTIPATH ERROR  R% VERSUS TARGET ELEVATION  %T  BOTH NORMALIZED TO RADAR  BEAMWIDTH P".   42!#+).' 2!$!2   °{£ 4HEORETICALLY  THE COUPLING TO CROSS 
 Because FIR filters require no feedback, they  are easier to use in very high-speed applications  than IIR filters, which typically require the compu - tation of an output sample before the next output  sample can be formed. Complex FIR filters, where  a complex multiplication is performed at each tap,  can be used to implement equalization filters, time  delays, and pulse compression filters. Figure 25.33 shows an alternative form for a  FIR filter, called a transposed form  FIR filter. 
 VI was about 3.5 Mc/s, with a pulse length of 1 μs. Dependent on the actual pulse shape and length, an ideal matched ﬁlter would have a bandwidth closer to 1 Mc/s. The broader IF response was used to provide some margin of error when tuning the klystron and to allow some frequencyAirborne Maritime Surveillance Radar, Volume 1 4-30. 
 1670–1681, July 1992. 23. G. 
 FED REFLECTOR CONFIGURATIONS  THE FOCAL AXIS GENERALLY DOES NOT INTERSECT THE REFLECTOR SURFACE &EEDS FOR OFFSET 
  
 Consequently, finger-type regu- lators have been used onradar systems only rarely. 14.6. Speed Regulators.—The a-c frequency generated bymotor- alternator sets varies over awide range with changes ininput voltage, load, altitude, and temperature. 
 Weikle, and M. DeLisio, “Failures in power combining arrays,”  IEEE Transactions on Microwave Theory and Techniques , vol. 47, no. 
 K. Moore, and A. K. 
 Since the average radiation intensity over a solid angle of 4n radians is equal to the total  rower radiated divided by 4n, the directive gain as defined by Eq. (7.1) can be written as  G O = 4n(maximum power radiated/unit solid angle)  total power radiated by the antenna {7.2)  This equation indicates the procedure whereby the directive gain may be found from the  radiation pattern. The maximum power per unit solid angle is obtained simply by inspection,  and the total power radiated is found by integrating the volume contained under the radiation  pattern. 
 I%rirrows, and 1. 13. I--e~.rcll: Ultra-short Wave Propagation, 1'r.oc.. 
 Electron. Comput. Re- sources Dig. 
 4.6  Common Problems  ............................................  4.7  4.3 Amplifier Chain Transmitters  ..................................  4.9  Oscilla tor versus Ampl ifier  ................................. 
 BEAM LINE 
    PP n  -AY   7 6 4 2USCH  h3CATTERING FROM A HYPERBOLOIDAL REFLECTOR IN A #ASSEGRAINIAN FEED SYSTEM v  )%%%  4RANS  VOL !0 
 MER   THEN IT COULD STILL BE ARGUED THAT NO TRACKS ARE BETTER THAN MANY FALSE TRACKS 3ECOND  NOT ALL JAMMERS ARE NOISE JAMMERS 3OME INDEED HAVE A STRUCTURE IN  RANGE 
 This inner core is sandwiched  between two thin outer layers, or skins, of a high-dielectric-constant material relative to that of  the core. The skins might typically have a dielectric constant of about 4, and the core might  have a value of about 1.2. The skins are thin compared to a wavelength. 
 2, 1964. (See also Chap. 6 of ref. 
 Weichert, “An AlGaAs/ InGaAs pseudomorphic high electron mobility transistor with improved breakdown voltage for  X- and Ku-band power applications,” IEEE Transactions on Microwave Theory and Techniques ,  vol. 41, no. 5, pp. 
 The cross section can  change by as much as 15 dB for a change in aspect of only 3". The maximum echo signal  occurs in the vicinity of broadside, where the projected area of the aircraft is largest.  It is not usually convenient to obtain the radar cross section of aircraft by mounting the  full-size aircraft on a rotating table. 
 However, radars for the surveillance and tracking of extraterrestrial targets,  such as satellites and spacecraft, might employ the dopplcr shift to measure directly the  relative velocity, but it is seldom used for this purpose in aircraft-surveillance radars. Instead,  aircraft-surveillance radars use the doppler frequency shift to separate the desired moving  targets from the undesired fixed clutter echoes, as in MTI radars.  If the target can be viewed from many directions, its shape can he determined. 
 Itisgood design practice toprotect against such interference, and, as will beseen later, the same provisions are sometimes ofvalue inthe absence ofinterference. These AJ (antijamming) provisions may merely beprecautions taken inthe design ofthe receiver which donot affect itsnormal operation, orthey may bespecial AJcircuits that can be switched inand out ofuse. Interference may beany ofseveral types such asCW, amplitude- modulated CW, frequency-modulated CW, r-fpulses, ornoise-modulated C!W, The more nearly the interference islike theechoes being received. 
 Spaulding and Washburn106 added data from the former U.S.S.R. for two  revised CCIR reports.105 Noise-level medians as a function of frequency are given in  the form of worldwide maps by season and 4-h time blocks. Lucas and Harper107 have  provided a numerical representation of CCIR Report 322-1, which is useful for com - puter computations, and this has been revised by adding the work of Spaulding and  Washburn. 
 One additional shel- ter is provided for maintenance aids. Radar surveillance coverage encompasses a volume out to 300 nmi and up to 100,000 ft with a 90 percent probability of de- tection within 200 nmi for a 1-m2 fluctuating target. The search volume is scanned mechanically in azimuth through 360° and electronically in elevation through 20°. 
 (2)weseethat Sti, isinversely proportional tothe square root ofbeamwidth 0. Allother factors that enter into thevalue ofS~,. cannow beconsidered asconstants and wecan therefore write where K2issmother constant. 
 ", - !IR 
 . 
 Y . Gorokhov, V . N. 
 3. If" pulses are integrated, the integration-improvement factor l;(n) = nE;(n) is found from  Fig. 2.24. 
 In practice the use of the cumulative probability is not easy to apply. Furthermore, radar  operators do not usually use such a criterion for reporting detections. They seldom report a  detection the first time it is observed, as is implied in the definition of cumulative probability. 
 This initially creates a broader beam with reduced gain. As  frequency continues to change, the two beams will eventually split apart. At broad - side, the center-fed antenna has poorer performance than a parallel feed since each  half scans. 
 However, theoverall conclusion was that the equipment performed well. References [1] Lucero Interrogation Equipment, TRE Report No. 33 R, 100/JWSP (T 1317), 1942 (TNA AVIA 26/319) [2] Lucero Interrogation Equipment, TRE Report No. 
   "' &"$%" &   '#%      %'     '  #")%& #"   ! '%  #   "%'#%   # & "& ' ) '+ !#"'%#   ('#!'   "#"'%#  ' # &   '#% 
 Here, ambiguous detections are  first amplitude centroided and then unfolded, as discussed previously, but with the  results stored in an array whose elements are the coarse bins. These bins have a size  less than or equal to the shortest IPP, and correlation involves scanning identical bins  across all of the PRFs in the dwell and applying a correlation window. In the example  shown in Figure 4.18, the bins are set to nine range gates (shortest IPP length), and the  fifth coarse bin contains detections across the three PRFs that fall within the correla - tion window of ± 0.3 range gates. 
 `` 
 12.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 Reflector Antennas Michael E. Cooley and Daniel Davis Electronic Systems   Northrop Grumman Corporation 12.1 INTRODUCTION Role of the Radar Reflector Antenna.  Radar reflector antennas provide the  means by which the transmit (receive) energy and its associated waveform is radiated  into (coupled from) free space. 
 TION OVER SMOOTH TERRAIN  THE LARGE GEOMETRIC AREA  AND RELATIVELY SHORT RANGE  THIS SIGNAL CAN BE LARGE )T LIES WITHIN THE SIDELOBE CLUTTER REGION OF THE PULSE DOPPLER SPECTRUM "ECAUSE IT CAN BE MUCH LARGER THAN DIFFUSE SIDELOBE CLUTTER AND USUALLY HAS A  RELATIVELY NARROW SPECTRAL WIDTH  ALTITUDE 
 The basic MTI concepts were introduced  during World War 11, and most of the signal processing theory on which MTI (and pulse  doppler) radar depends was formulated during the mid-1950s. However, the reduction of  theory to practice was paced by the availability of the necessary signal-processing technology.  It took almost twenty years for the full capabilities offered by MTI signal-processing theory to  be converted into practical and economical radar equipment. 
 NUMBERED COEFFICIENTS TO BE PURELY REAL AND PURELY IMAGINARY  RESPECTIVELY  SO THE EVEN 
 TERM STABILITY MAINLY AFFECTS VELOCITY OR RANGE ACCURACY OR SPURIOUS SIGNALS  DUE TO 02& HARMONICS   BUT IS RELATIVELY EASY TO MAKE ADEQUATE 3HORT 
 ROll1c 11ir/)CI'e/0f!IIICllt CCllterTechllical DOCllll1ellt aryReportNo.RADC-TDR-64-42I, December. 1964. 10(,.Earth-based Electronics. 
 RADAR ANTENNAS 225  The radiation pattern shown in Fig. 7.1 is plotted as a function of one angular coordinate,  but the actual pattern is a plot of the radiation intensity P(O, cp) as a function of the two angles  0 and ¢. The two angle coordinates commonly employed with ground-based antennas are  azimuth and elevation, but any other convenient set of angles can be used. 
 COEFFICIENT 
 TONICALLY AS THE TRACKING GAIN  @ DECREASES TO  #ONVERSELY  WHEN THE TARGET IS PER 
  AND +U 
 P. Gogineni, F. A. 
   4(% 2!$!2 42!.3-)44%2   £ä°£Ç "ECAUSE THE #&! HAS RELATIVELY LOW GAIN  IT IS SOMETIMES USED ONLY IN ONE OR TWO  OF THE HIGHEST 
 Luneburg-lens reflectors  are used for making strong radar targets of small vessels, and they may be obtained  FIGURE   16. 12 CW-scatterometer-system block diagram: ( a) separate transmitter and receiver   calibration and ( b) calibration of the ratio of received to transmitted power ch16.indd   20 12/19/07   4:55:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Klystrons haveseenwideapplication inradar.Severalexamples ofradarpulse klystrons willbebrieflymentioned. TheVA-87E, showninFig.6.10,isa6-cavity, S-band klystron tunableovertherangefrom2.7to2.9GHz.Itwasdesigned tomeettherequirements fortheASR-8Airport Surveillance Radar.Ithasapeakpowerof0.5to2.0MWandan averagepowerof0.5to3.5kW.Thegainisnominally 50dBanditsefficiency isgreaterthan45 percent. ItsI-dBbandwidth is39MHz,butitisinherently capableofgreatervalues.Apeak. 
 Chapter 22 †  A list of all used maritime abbreviations is included at the end of the chapter. ch22.indd   1 12/17/07   3:02:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 D" IMPROVEMENT OVER PSEUDORANDOM SEQUENCES OF SIMILAR LENGTH 4HE AMBIGUITY FUNCTION GROSSLY RESEMBLES THE KNIFE 
 2, 1969.  95. Chow, P. 
 ................................ ................................ ............. 
 124 advantage that cascaded double-tuned circuits donot narrow asrapidfy ascascaded single-tuned circuits because ofthe rectangular form ofthe response curve (Fig. 12-8). For example, nine cascaded single-tuned stages, each of6-Me/see bandwidth, would have anover-all bandwidth of1.7Me/see. 
  !LTI+A IS SINGLE 
 (5) If the drop in the voltage of G2 which would be  caused by the drop in the potential of G3 is greater than  the drop of potential of G3, the circuit will change  violently to a completely different condition. This is  the unstable state, which is used in the ‘flip-flop.’  Case (a) corresponds to the condition of the multi-  vib, in which, as we have seen, the extra voltage change  on A’s grid is Jess than the original voltage change  causing it. Case (é) corresponds to that in which the  extra voltage change on A’s grid is greater than the  original voltage change causing it. 
 116 INTRODUCTION TO RADAR SYSTEMS  5  0  5  -15  iD :g  OJ 10  "' C  0  ~ -20  Q.)  0:  -25  -30  -35 5  0  --5  Symmetrical --1 5  about  vlv8 14.125 -1 0  20  25  30  35  40  Figure 4.17 Frequency response of a five-pulse (four-period) stagger. (From Shrader,8 Co11rteS}' McGraw­ Hill Book Co.)  constant period equal to the average period Tav = (T1 + T2 + · · · TN)/ N, then the first blind  speed 111 is  v1 n1 + n2 + · · · + nN -= --------- VB N ( 4.11)  It is also possible to apply weighting to the received pulses of a staggered prf waveform.  An example is shown in Fig. 
 Range (R): The range in the equation is the distance along the virtual path between target and radar. The ionospheric reflection height needs to be used to convert this range to great-circle ground distance. The apparent range to a particular target may take on more than one value since multiple paths may exist. 
 W. M.: The Measurement of Large Antennas with Cosmic Radio Sources," IEEE Trans.,  vol. AP-21, pp. 
 I'he cosecant-squared pattern in Fig. 7.26b is shown as a uniform beam over the  range 0 i 0 5 0, arid decreases as csc2 O/csc2 8, over the range 0, < 8 2 Om. The gain G of the  square beam in Fig. 
 Lineararraywithfrequency scan,.Thefrequency-scanned, lineararrayfeedingaparabolic cylinder oraplanararrayof.slotted.waveguides hasseenwideapplication asa3D air-surveillance radar.Inthisapplication, apencilbeamisscanned inelevation byuseof frequency andscanned inazimuth :bymechanical rotation oftheentireantenna. Lineararraywithphasescan.,Electronic phasesteering, insteadoffrequency scanning, inthe 3Dair-sur,veillance radarisgenerally moreexpensive, butallowstheuseofthefrequency domain forpurposes otherthanbeamsteering. Thelineararrayconfiguration isalsoused togenerate multiple, contiguous fixedbeams(stacked beams)for3Dradar.Another application istouseeitherphase-orfrequency-steering inastationary lineararrayto steerthebeaminoneangularcoordinate, asfortheGCAradar. 
 Theoutputwaveform extends adistance Ttoeithersideofthepeak response, orcentralspike.Theportions oftheoutputwaveform otherthanthespikearecalled timesitlelobes. Thebinarychoiceof0or1tphaseforeachsubpulse maybemadeatrandom. However, somerandomselections maybebettersuitedthanothersforradarapplication. 
 4.2 PULSE DOPPLER CLUTTER General.  Clutter returns from various scatterers have a strong influence on the design  of a pulse doppler radar as well as an effect on the probability of detection of point targets.  Clutter scatterers include terrain (both land and sea), weather (rain, snow, etc.), and chaff. 
 --  4HE THREE BASIC PERMUTATIONS OF '02 DATA PRESENTATION ARE SHOWN IN &IGURE  4HE MOST BASIC '02 DATA RECORD IS AN ! 
 AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 Automatic tracking can generally be divided into the five steps shown in Figure 7.25  and detailed here: 1. Radar detection acceptance: accepting or rejecting detections for insertion into the  tracking process. The purpose of this step is to control false track rates. 
 ON MAINTENANCE NOR IN 
 TheC-scope.—The type Cdisplay presents theazimuth and elevation angle coordinates ofthe scanner asrectangular coordinates onthetube. 174 THEGATHERING ANDPRESENTATION OFRADAR DATA [SEC. 67 face (Fig. 
 PHASE FILTERS THAT REQUIRE FEWER PULSES  AS SHOWN IN &IGURE  "ECAUSE ONLY A FIXED NUMBER OF PULSES IS AVAILABLE DURING THE TIME ON TARGET  NONE SHOULD BE WASTED 4HUS  ONE SHOULD CHOOSE THE NONLINEAR 
 TION OF THE SAMPLE RATE   AND AS AN INTEGRAL PART OF )1 GENERATION 3ECTION  DESCRIBED HOW SPURIOUS RESPONSES ARE GENERATED IN THE MIXING PROCESS  5NWANTED INTERFERENCE SIGNALS CAN BE TRANSLATED TO THE DESIRED INTERMEDIATE FREQUENCY EVEN THOUGH THEY ARE WELL SEPARATED FROM THE SIGNAL FREQUENCY AT THE INPUT TO THE MIXER 4HE ABILITY OF THE RADAR TO SUPPRESS SUCH UNWANTED INTERFERENCE IS DEPENDENT UPON THE FILTERING PRECEDING THE MIXER AS WELL AS ON THE QUALITY OF THE MIXER ITSELF. 
 ING THE BEST FEATURES OF THE VARIOUS OTHER MODELS IN A HYBRID MODEL /NCE SUCH MODEL IS THE !DVANCED 0ROPAGATION -ODEL !0-  DESCRIBED BY "ARRIOS  )N !0-  THE 0%  MODEL IS COMBINED WITH VARIOUS RAY OPTICS AND OTHER PHENOMENA MODELS TO CREATE A HYBRID MODEL THAT CAN BE UP TO  TIMES FASTER THAN A 0% MODEL FOR STRESSFUL CASES 4HREE OTHER HYBRID MODELS ARE 2ADIO 0HYSICAL /PTICS 20/    4%20%- AUTHORED BY  3IGNAL 3CIENCE ,IMITED  AND A HYBRID METHOD FOR COMPUTING TRANSMISSION LOSSES IN  AN INHOMOGENEOUS ATMOSPHERE OVER IRREGULAR TERRAIN BY -ARCUS 7ITHIN !0-  THE ASSESSMENT SPACE IS DIVIDED INTO FOUR REGIONS  OR SUBMODELS  AS  ILLUSTRATED IN &IGURE  !T RANGES LESS THAN  M AND FOR ALL ELEVATION ANGLES ABOVE   !0- USES A FLAT EARTH &%  MODEL THAT IGNORES REFRACTION AND EARTH CURVATURE EFFECTS &OR RANGES BEYOND THE &% REGION WHERE THE GRAZING ANGLES OF REFLECTED RAYS FROM THE TRANSMITTER EXCEED A SMALL LIMITING VALUE  A FULL RAY OPTIC 2/  MODEL IS USED THAT ACCOUNTS FOR THE EFFECTS OF REFRACTION AND EARTH CURVATURE 4HE 0% MODEL IS USED FOR RANGES BEYOND THE 2/ REGION  BUT ONLY FOR ALTITUDES BELOW A MAXIMUM 0% ALTI 
 Jr., and G. H. Stevens: A Technique for the Generation or Highly Linear FM Pulse  Radar Signals, I £EE Trans .. 
 D., J. G. Marangoni, and W. 
 ) 1 5 6%% %% %%HV HV HV  2E    )M  %%HV§ ©¨ ¨¨¨ ¨¶ ¸· ··· ·    4HE INDIVIDUAL 3TOKES PARAMETERS )   1  5  AND 6 ARE DEFINED AS SHOWN IN %Q  &)'52%     %XAMPLE OF FREQUENCY RESPONSE OF R   FOR DIFFERENT KINDS OF SEA ICE  FROM 9 3 +IM .   '2/5.$ %#(/  £È°{ 3OME OF THE RETURN SIGNALS FROM A RESOLUTION CELL MAINTAIN THEIR POLARIZATION CHARAC 
 The practical consequences ofthis become serious asfrequencies of1000 Me/see are approached. The reduction ofcathode and plate areas, which under these conditions vary asA2,rapidly reduces theavailable peak emission and plate dissipa- tion. Electrode clearances become sosmall that they are difficult to maintain accurately. 
 ...... 10  Theoretical Maximum Range Equation  ................................ ................................ 
 Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 21.40  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 REFERENCES  1. D. 
 L. Hicks, N. Knable, J. 
 6.Lerner, R.M.:AMatched FilterDetection SystemforComplicated Doppler ShinedSignals, pp.373-385. 7.Cutronfo L.J.,E.N.Leith,CJ.Palermo, andL.J.Porcello: OpticalDataProcessing andFiltering Systems, pp.386-400. 8.Welte,G.R.:Quaternary CodesforPulsedRadar,pp.400-408. 
 620-628, September, 1970.  62. Popov, G. 
 Itisanelectronic servo-mech- anism that tunes thelocal oscillator in FIG. 12.11 .—Height ofdiscriminator output pulses, where foisthe transmittersuch away that the proper difference frequency andf;isthe intermediate frequency between itand the mag- frequency.netron ismaintained. The speed of tuning canusually begreat enough tofollow any pulling ofthemagnetron that may occur during the scanning cycle. 
 3ANDWICH ! COMMONLY USED RADOME 
 181–186. 195. S. 
 Using the calculus of variations, Mallinckrodt and Sollenberger3 show that the Fourier  transform S,(f) of the optimum gating function which minimizes the time-delay error  [Eq. (1 1.8)] is given, except for an arbitrary constant factor, by  Figure 11.3 Effect of noise n(t) in shifting the apparent zero crossing of the output s0(TR - To) of the  gating receiver of Fig. 11.2. 
 CAME THE LIMITATIONS OF THE MAGNETRON !LTHOUGH THE MAGNETRON HAS HAD IMPORTANT APPLICATIONS IN THE PA ST  IT HAS ALSO HAD  SERIOUS LIMITATIONS THAT CONSTRAIN ITS USEFULNESS FOR RADAR )TS MAJOR LIMITATIONS ARE ITS POOR STABILITY WHICH LIMITS THE ABILITY TO DETECT MOVING TARGETS IN CLUTTER  ITS RELATIVELY MODEST AVERAGE POWER  AND ITS SIGNAL CANNOT BE READILY MODULATE D FOR PULSE COMPRES 
 TO 
 Ileart. H. K.. 
 Safety  aids use radar beacons extensively, and a wartime air-  sea-rescue system which has now grown up to peace-  . 158 HOW RADAR WORKS  time proportions uses a rather ingenious radar beacon.  This incorporates a squegging oscillator which can be  coded in dot-and-dash form, to act as a beacon to  ifn i  (6) Runway on left or aircraft too much to starboard. 
 Itisfrequently essential, however, toprovide adjust- ments foraccurately orienting the scanner base. Toallow this adjust- ment itiscustomary that the short length oftransmission line between thescanner and ther-funit beflexible: this flexibility yalso allows ther-f unit tobeshock-mounted. 9.20. 
 QST.vol.211.p.II.h:brll­ ary.1936. 54.Carpentier, M.H.:..Radars: NewConcepts," Gordon andBreach, NewYork.I96H.sec.4.6 55.Severin, H.:Nonretlecting Absorbers forMicrowave Radiation. IRETrailS.,vol.AP-·,t,pp.~X51l)2. 
 BLED FROM A GREAT MANY SIMILAR RADIATING ELEMENTS  SUCH AS SLOTS  DIPOLES  OR PATCHES  EACH ELEMENT BEING INDIVIDUALLY CONTROLLED IN PHASE AND AMPLITUDE !CCURATELY PRE 
 The two 20-m long elements were  not unfurled until two years into the mission, due to concerns about their potential  for damaging the spacecraft during deployment. The effective cross-track footprint  is on the order of 25 km. The along-track footprint is about 5 km, which is the result  of onboard coherent doppler processing. 
 CHANNEL 3!2 JAMMED BY A SMALL  WATT .   %,%#42/.)# #/5.4%2 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Radar Transmitter. 10.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 and its predecessors (the IOT and the Klystrode) are the only RF power sources that  can operate efficiently when amplitude shaped waveforms are desired for minimizing  out-of-band interference to other radars. 
 TO 
   '2/5.$ %#(/  £È° 0HYSICAL  /PTICS  -ODELS  4HEORIES BASED ON APPLICATIONS OF THE +IRCHHOFF 
 Another  critical issue is the observed systematic variation of the external noise level, which has  a direct impact on radar performance. The major source of quasi-continuum background noise at the lower frequencies  is lightning discharges ionospherically propagated from all over the world (sferics).  At the high-end of the band, extraterrestrial or galactic noise may be greater than that  due to sferics. 
 Military SBR Systems. Brookner and Mahoney11 derived a satellite radar architecture for performing the basic surveillance missions for the fleet defense and air defense of the CONUS. The system was an L-band, corporate-fed phased array radar in orbit constellations of 3 to 12 satellites at altitudes from 600 to 2000 nmi. 
 Oliphant, of Birmingham University,  and Dr H. W. B. 
 TER LOCATED WITHIN THE SUBARRAY PATTERN $"& AT THE SUBARRAY LEVEL USES PHASE SHIFTERS AT THE ELEMENT AND AN ANALOG SUBARRAY BEAMFORMER  WITH A DIGITAL RECEIVER LOCATED AT THE OUTPUT OF EACH SUBARRAY 4 IME DELAY STEERING  CAN BE ACHIEVED AT THE SUBARRAY LEVEL  THROUGH THE USE OF DIGITAL TIME DELAYS 4HE MULTIPLE BEAM CLUSTER IS FORMED BY DIGITALLY COMBINING THE SUBARRAYS TO FORM SIMULTANEOUS BEAMS THAT ARE OFFSET FROM ONE ANOTHER )N PRACTICE  $"& IS FREQUENTLY IMPLEMENTED AT THE SUBARRAY LEVEL RATHER THAN THE ELE 
 The precision variable-delay circuit directly provides the trigger forthe delayed sweep. An index marker ispr~ vialed atthe center ofthesweep byasecond fixed-delay circuit, usually aflip-flop, whose action isinitiated bythe sweep trigger. The timing arrangements areobvious from thewaveform diagram. 
 (This jamming technique is called jog detection .13) A sequential lobing-   on-receive only (LORO) system conceals the lobing rate from a potential jammer.3  Conical scan and sequential lobing are going to be replaced by the monopulse tech - nique; thus, COSRO and LORO are becoming obsolete. Monopulse tracking is inherently insensitive to angle deceptive jamming from a  single point source. This is a result of the monopulse angle-error-sensing mechanism  that forms an error proportional to the angle between the target and the antenna’s  boresight on each return pulse. 
 In the interest of even  further accuracy, a correction is usually made to Eq. (13.15) to account for the fact that the  effective volume of uniform rain illuminated by the two-way radar antenna pattern is less than  that indicated when the half-power beamwidths are used to define the volume. Assuming a  gaussiari-shaped antenna pattern, the volume given by Eq. 
 Probability of detection ( Pd)  depends on target signal-to-noise ratio and probability of false alarm ( PFA), which  itself is a function of waveform. The false alarm probability determines the detection  threshold and is referenced to an individual range-doppler cell. This per-cell probabil - ity is derived from the specified false report time for the system. 
 DEFENSE GAP FILLING  0!2!$/0 AND  -)$/0 RANGE 
 Picciotti, and G. Vulpiani, “Rain field and reflectivity vertical profile reconstruction  from C-band radar volumetric data,” IEEE Trans Geosci Rem. Sens ., vol. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.66  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 phase change if a power amplifier, from the inability to lock the coho perfectly to the  phase of the reference pulse, from time jitter and amplitude jitter on the pulses, and  from quantization noise of the A/D converter.36,37 Phase instabilities will be considered first. 
 Thus, Mitzner’s expres - sion for the scattered field contains only the contributions from the filamentary edge  currents. In applying his theory to scattering objects, therefore, the contributions of  nonfilamentary-induced surface currents must be accounted for separately, just as in  Ufimtsev’s PTD. When the directions of incidence and scattering become perpendicu - lar to an edge, the perpendicular-parallel terms disappear and Mitzner’s diffraction  coefficients then reduce identically to Ufimtsev’s. 
 Emerson, R. C.: Some Pulsed Doppler MTI and AMTI Techniques, RAND Corp. Report 110. 
 Clapp, R. E.: A Theoretical and Experimental Study of Radar Ground Return. ,\f/T Radiation  Laboratory Rept. 
 Thereceiver inputymaybe eithersignal-plus-noise ornoisealone.Therefore theprobability oftheeventymaybeex­ pressed as p(y)=p(yISN)p(SN)+p(yIN)p(N) Theaposteriori probability ofEq.(10.23)becomes N_ p(SN)p(yISN) p(SIy)-p(yISN)p(SN)+p(yIN)p(N) r Or,intermsofthelikelihood rati030 L ( )=p(yIS~J , yp(yIN) L,(y)p(SN) p(SNIy)=L,(y)p(SN)+1-p(SN)(10.29) (10.30) (10.31) Therefore, ifareceiver canbebuiltwhichcomputes thelikelihood ratioandiftheapriori probability p(SN)isknown,theaposteriori probability canbecalculated. Sincep(SNIY) isa monotonic function ofL,(y),theoutputofthelikelihood receiver (orthematched-filter receiver) canbecalibrated directly intermsoftheaposteriori probability. Thechiefdifference between thetworepresentations isthattheconcept ofinverse probability requires aknowlege oftheaprioriprobabilities whereas thelikelihood ratiodoesnot.(Thelikelihood ratiofollows frominverseprobability iftheassumption ismadethattheaprioriprobabilities areequally likely.)Boththeaposteriori method andthelikelihood method maybeimplemented by computing thecross-correlation function between thereceived signalandthesignals,(t).. 
 TRIC GROUND CONSTANTS MAY BE SELECTED FROM THOSE DEFINED BY THE )NTERNATIONAL 4ELECOMMUNICATION 5NION  )NTERNATIONAL 2ADIO #ONSULTATIVE #OMMITTEE ##)2     OR FROM ANY OTHER SUITABLE SOURCE.   4(% 02/0!'!4)/. &!#4/2  &0  ). 4(% 2!$!2 %15!4)/.   ÓÈ°£ !2%03 CONSIDERS RANGE 
 TIME SIMULATION OF THE ENTIRE GEOMETRY AND EXTERNAL WORLD IN THE RADAR INTEGRATION LABORATORY IS COMMONLY EMPLOYED !CTIVE %LECTRONICALLY 3CANNED !RRAY !%3!   !LTHOUGH MULTIFUNCTIONAL RADARS  HAVE BEEN DEPLOYED WITH MECHANICALLY SCANNED AND ELECTRONICALLY SCANNED ANTENNAS  FULLY MULTIFUNCTIONAL RADARS USE !CTIVE %LECTRONICALLY 3CANNED !RRAYS !%3!   WHICH CONTAIN A TRANSMIT 
 Ifthe system isrequired tohandle more than one target atatime, discrimination may bemade either onthe basis ofrange orofdoppler frequency. Ifrange isused, more sidebands are called for, and the 1The theorem would beexact ifthecarrier frequency were anintegral multiple ofthemodulation frequency. When thisisnotso,thedeviations areoftheorder ~,/fo orlessandareusually negligible.. 
 SECTION RATIO WERE SUF 
 FREQUENCY 02&  RADAR IS GIVEN BY   & .YQ   o 02&    WHERE 02& IS THE PULSE REPETITION FREQUENCY 3IMULTANEOUSLY  THE UNAMBIGUOUS RANGE  INTERVAL IS GIVEN BY   2C A 0 2 &    4!",%  !TTENUATION #AUSED BY #LOUDS OR &OG 4EMPERATURE   n# !TTENUATION  D"KM 6ISIBILITY  M K    CM K    CM K    CM                                   .   -%4%/2/,/')#!, 2!$!2   £°£Î AND THE PRODUCT &.YQ 2A IS SIMPLY  &2C .YQ A     3INCE  THE DOPPLER SHIFT  F AND THE TARGET RADIAL VELOCITY  V ARE LINEARLY RELATED  THE  UNAMBIGUOUS VELOCITY IS RELATED TO THE .YQUIST FREQUENCY BY   6&A L .YQ    )T FOLLOWS THAT THE PRODUCT OF UNAMBIGUOUS VELOCITY AND UNAMBIGUOUS RANGE IS   62C AA L     &OR  CONSTANT 02& RADARS  THIS PRODUCT IS MAXIMIZED BY MAXIMIZING  K  THE TRANSMIT 
 Al·S-1  pp. 486-503, September, 1977.  44. 
 TIME ADAPTIVE ARRAY PROCESSING IS SHOWN IN &IGURE  !N INDIVIDUAL DUPLEXER IS PLACED BETWEEN EACH TRANSMITTERS CHANNELIZED OUTPUT AND ITS CORRESPONDING ANTENNA ELEMENT 0ROVISION COULD BE INCLUDED FOR ELECTRONIC BEAM STEERING USING HIGH 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 Ocean currents can be determined when a zero doppler reference (such as an island)  is in the radar footprint.92 The NOAA Wavewatch website93 provides access to  archived maps of significant waveheight, dominant wave period, and other param - eters; such information is extremely helpful when designing a radar for remote sens - ing applications. In addition to providing information about the sea surface, HF radar can be used  to infer surface wind speed and direction.87,94 Wind direction is commonly estimated  by taking the ratio of the first-order resonant Bragg peaks and employing an empirical  relationship between this ratio and the wind direction relative to the radar look axis, as  pioneered by Long and Trizna.87 By scanning over a radar’s coverage area, a map of  inferred wind direction can be constructed; surface-wind direction maps are a routine  byproduct of the Jindalee radar.76 While waveheight and wave spectrum estimates can, in principle, be extracted  from higher-order features of skywave radar sea-echo spectra, a major difficulty  arises due to the myriad forms of contamination and distortion introduced by the  ionosphere. 
 32 Angle accuracy, by beam splitting, 7.5 to 7.7 Angle measurement errors, 9.43 to 9.44 Angle noise, 9.30 to 9.35 Angle scintillation (glint), 9.30 to 9.35, 9.47 Angular direction, 1.8 Anomalous propagation, 26.6 to 26.13 Antenna-related ECCM, 24.10 to 24.31 Antennas, 1.2, 1.4 to 1.5. See also phased arrays, reflector antennas basic principles, 12.3 to 12.15 for civil marine radar, 22.10 to 22.12 for ground penetrating radar, 21.24 to 21.30 phased array, 13.2 to 13.3 for pulse doppler, 4. 12 to 4.13 reflector antennas, role of, 12.1 reflector antennas, types of, 12.7 Anti-radiation missile (ARM), 24.40 Anti-range-gate pull-off (A-RGPO), 24.46 Aperture gain, of antennas, 12.4 to 12.5 Apollo Lunar Sounder, 18.60 to 18.61 Aquarius scatterometer, 18.58 Area MTI, 2.84 Array feeds, for reflector antennas, 12.28 to 12.30 AR SR-4, 12.30 ASR-9, 10.27 to 10.28, 12.20 to 12.21 ASR-11 MTI filter design, 2.50 to 2.51 ASR-12, 8.30, 10.27 to 10.28 Atmosphere, of the Earth, 26.2 Atmospheric ducts, 26.7 to 26.10 Attenuation, by clouds, 19.7 to 19.8 by fog, 19. 
 TICULAR  THE COMMERCIAL COMMUNICATIONS INDUSTRY HAS FOUND THAT THE 3I ,$-/3 &%4 DOMINATES AS A CELL PHONE BASE 
 The coordinate center is chosen at the IPP position and the x-axis, y-axis, and z-axis are deﬁned as the magnetic north, magnetic east, and vertical down to the earth. θand ϕare the ionospheric incident angle and magnetic heading of radar beam center. To make an explicit description, we neglect the inclined angle between the magnetic heading of radar platform and the magnetic east. 
 The positions for the local oscillator output socket, the mixer current control, mixer current meter and the tuning control were blanked off. Some of the controls previously available as pre-setadjustments (contrast, focus, shift etc) had been provided with knobs, perhaps indicating the need for more frequent adjustment than previously anticipated. The similar indicator unit type 162C, used on ASV Mk. 
 dbofi-famplifier gain and anover-all bandwidth of12Me/see. This was accomplished with only nine 6AK5 tubes inthe i-famplifier (Sec. 12.11). 
  !N EXAMPLE OF CLUTTER RESIDUE FROM SIMULATED HARD 
 Curry, and J. T. Francis: An Adaptive Threshold System for  Nonstationary Noise Backgrounds, IEEE Trans., vol. 
 138 C-W RADAR SYSTEMS [SEC, 5.6 relatively small i-famplifications canbeused, theremaining amplification being done after thesecond detector. The most important consideration indoppler work iskeeping the transmitter frequency modulation down. This will bediscussed in Transmitter receiverunit Elevation scale’/’// Transmitting/ //,. 
 change and no-change. •Change maps: Use the two classes to generate the combined change map. Divide the combined change map into two separate change maps based on the changes that occur in the images. 
 It can also observe the target  over a period of time so as to obtain its track. Moving target indication (MTI) . This is a pulse radar that detects moving targets  in clutter by using a low pulse repetition frequency (PRF) that usually has no  range ambiguities. 
 This lack of phase adjustment imposes a max- imum upon the synthetic antenna length that can be generated. This maximum synthetic antenna length occurs at a given range when the round-trip distance from a radar target to the center of the synthetic array differs by X/4 from the round-trip distance between the radar target and the extremities of the synthetic aperture array. The pertinent geometry is shown in Fig. 
 L.: 360° Azimuth Scanning · Antenna Without Rotating RF Joints, U.S. Patent  no. 3,916,416, Oct. 
 7/HGH, August 1943 (TNA AVIA 26/1082) [13] Performance of A.S.V. Mk. III in Wellington XII Aircraft, C.C.D.U. 
 WIND DIRECT ION MAPS ARE A ROUTINE  BYPRODUCT OF THE *INDALEE RADAR 7HILE WAVEHEIGHT AND WAVE SPECTRUM ESTIMATES CAN  IN PRINCIPLE  BE EXTRACTED  FROM HIGHER 
 MANCE LEVEL LOWER THAN THAT OF A SINGLE CANCELER. Î°ÎÓ  2!$!2 (!.$"//+  Î°££Ê 
 Sensors 2019 ,19, 2161 5. Simulation In this section, the point target and extended target simulation are performed to present the scintillation effect on P-band sliding spotlight system, and a group of 500-time Monte-Carlo simulations are carried out to validate the theoretical analysis. The typical P-band LEO SAR system parameters are applied to carry out the simulation. 
 E. IS tile  wavelength in centimeters, In1 (- K) is the rmaginary part of - K, and K is a factor whicll  clcpcndc ilpori tlic dielectric coristant of thc particle. At a temperature of 10°C. 
 CLUTTER USING  JOINT TIME 
 Ciresan, D.C.; Meier, U.; Masci, J.; Gambardella, L.M.; Schmidhuber, J. Flexible, high performance convolutional neural networks for image classiﬁcation. In Proceedings of the IJCAI Proceedings-International Joint Conference on Artiﬁcial Intelligence, Barcelona, Spain, 16–22 July 2011; Volume 22, p. 
 Thus, the imaging quality of the target P on the reference plane will decrease. Then, we derive the condition for the defocusing of the ArcSAR imaging result on the reference plane. According to Equation (11), the occurrence of Δpis due to the slant range error caused by Rp and Rp0. 
 AN/SPS-40 Shipboard Search Radar.  The AN/SPS-40 was an existing UHF,  tube-type, long-range, 2D shipboard search radar system, for which a new solid-state  transmitter was built during the 1980s to replace the tube. The solid-state transmitter  was built for the Naval Sea Systems Command by the (then) Westinghouse Electric  Corporation.34 The existing waveform from the original transmitter was not changed,  and the solid-state unit was installed as a direct retrofit. 
 Twobasiclimitations toanyofthefeedconfigurations mentioned aboveareaperture blocking andimpedance mismatch in,thefeed.Thefeed,transmission line,andsupporting structure intercept aportionofthe.radiated energyandaltertheeffective antenna pattern. Someoftheenergyreflected bytheparaboloid entersthefeedandactsasanyotherwave traveling inthereversedirection inthetransmission line.Standing wavesareproduced along theline,causinganimpedance mismatch andadegradation ofthetransmitter performance. Themismatch canbecorrected byanimpedance-matching device,butthisremedyiseffective onlyoverarelatively narrowfrequency band.Another technique forreducing theeffectofthe reflected radiation intercepted bythefeedistoraiseaportionofthereflecting surfaceatthe. 
 TENTIONAL CONVERSION OF !- TO 0- NOISE OCCURS IN THE RECEIVER CHAIN 4HIS PROCESS CAN OCCUR VIA SUBOPTIMUM COMPONENT BIAS TECHNIQUES WHERE HIGH AMPLITUDE SIGNALS OR NOISE CREATE A PHASE SHIFT RESULTING IN ANOTHER PHASE NOISE CONTRIBUTION TO THE RECEIVER CHAIN 6IBRATION 3ENSITIVITY  )N ADDITION TO THE PHASE NOISE GENERATED BY THE 34!,/ IN  A BENIGN ENVIRONMENT  SOURCES OF UNWANTED PHASE MODULATION INCLUDE THE EFFECTS OF POWER SUPPLY RIPPLE AND SPURIOUS SIGNALS AS WELL AS MECHANICAL OR ACOUSTIC VIBRATION FROM FANS  MOTORS  AND OTHER SOURCES 4HE EFFECTS OF VIBRATION CAN BE SEVERE  ESPE 
 If the estimate is in AVERAGE SCR IMPROVEMENT ISCR (dB) MTI IMPROVEMENT FACTOR (dB) OPTIMUMMTI MTI WITH BINOMIALCOEFFICIENTS . error, the actual performance may fall below that of the binomial-weight MTI canceler. 75.7 MTICLUTTERFILTERDESIGN The MTI block diagram shown in Fig. 
 25.5. This section considers measured and estimated values of o^0, which vary as a function of the surface composition, frequency, and geometry. And, in contrast to the monostatic case, little measured data for cr^0 has been reported.42'43'107"115 The available database for terrain and sea clutter at microwave frequencies consists of six measurement programs, which are summarized in Table 25.2. 
 BEAM CLUTTER IS BELOW THE THERMAL 
 The pulse-limited area Ap is  A r c hP P R = =π π τ α2( ) / (18.17) As the pulse continues to impinge and spread over the surface, the resulting pulse- limited annuli all have areas equal to that of the initial pulse-limited footprint. Hence,  the received power tends to maintain the level corresponding to the peak of the initial  response (Figure 18.10). The pulse-limited areas expand in response to increasing  large-scale surface roughness, which in the oceanographic context is expressed as  significant wave height (SWH). 
 the ARSR-J (Table 14.1) will be described. No claim is made that the  rationale given for each characteristic was that which innuenced the original specifications for  this radar. The brief discussion here is simply meant to convey some of the general philosophy  that might enter into radar design. 
 19. Rohling, H.: Radar CFAR Thresholding in Clutter and Multiple Target Situations, IEEE Trans., vol. AES-19, pp. 
 BASED METEOROLOGICAL RADARS ARE MEASURING  WIDESPREAD EQUATORIAL PRECIPITATION FIELDS AND CLOUD PROPERTIES  -ETEOROLOGICAL RESEARCH  RESULTS ARE REGULARLY TRANSFERRED TO THE OPERATIONAL WEATHER RADAR COMMUNITY FOR ACHIEV 
 A Nyquist bound applies and  requires the two-sided IF bandwidth to be less than the sampling rate. Now let’s derive the direct-DDC architecture carefully in the frequency domain.  Suppose a real IF signal is once again centered at 75 MHz and sampled at 100 MHz  as in line (a) of Figure 25.13. 
 D. Griffiths et al., “Measurement and analysis of ambiguity functions of off-air signals for  passive coherent location,” Electronics Letters , vol. 39, no. 
 Based on the unique mapping between such offset and the Doppler parameters, the DPEC can be accurately implemented. The paper is arranged as follows. Section 2introduces the basic MAM method. 
 Instead of the collector electrode found in the klystron an<l the  T\VT. the spent electrons terminate in the crossed-field amplifier on the slow-wave anode  s true! u re.  The CF A. 
 STATE !.303 
 NADIRv n nn   WHICH REFERS TO THEIR ELEVATION  WITH RESPECT TO VERTICAL IN SPACECRAFT COORDINATES  RATHER THAN THEIR INTERSECTION RELA 
 The voltage de-  veloped across condenser C before each successive dis-  charge through Vb is dependent upon the extent by  which the grid of Vb is maintained negative relative to  the anode by the voltage drop across Re. Adjustment  of the magnitude of this latter resistance therefore gives  us control of amplitude. Synchronization of the time-  base with outside circuits is effected by injecting a  fraction of the working voltage into one of the grids of  Vc. 
 ,- 4HE PERFORMANCE OF AIRBORNE -4) SYSTEMS ARE PRIMARILY DETERMINED BY MOTION EFFECTS INDUCED ON THE CLUTTER ECHOES PLATFORM MOTION  ANTENNA SCANNING MOTION  AND CLUTTER INTER 
 ERROR FILTERING !CCURATE SYSTEM CALIBRATION ALSO GREATLY REDUCES INTERNAL SOURCES OF ERROR &REQUENT  CALIBRATION CORRECTS FOR DRIFT IN COMPONENT GAIN AND PHASE AND  PEDESTAL FLEXURE /THER  INTERNAL SOURCES OF ERROR WITH KNOWN CHARACTERISTICS CAN BE AUTOMATICALLY CORRECTED TO MINIMIZE THEIR CONTAMINATION OF THE OUTPUT DATA , 
 This avoids the typical compromise and greater com - plexity of a polarization-controlled monopulse feed as described in Figure 9.8. ● Electronic scan array lenses can also refocus from a transmit feed horn to an adjacent  receive feed horn on reception to allow high power transmission through a simple  single horn feed to simplify isolation of the receiver from the transmit power . ● Arrays allow greater flexibility to optimize amplitude distribution of the radiated  energy across the array to reduce sidelobes. 
 l11tcrnatia11ai Cm1(i!re11ce RADAR-77, pp. 559-563. IEE (London) Conf. 
 ORBIT TRANSLATION OF 6ENUS SURFACE DUE TO PLANET ROTATION 4HE PERIOD OF THE ELLIPTICAL ORBIT WAS SELECTED TO BE ABOUT THREE HOURS  SO THAT IN SUCCESSION EACH IMAGING PASS OVERLAPPED AND EXTENDED THE SURFACE IMAGED ON PREVIOUS PASSES )N THE ALONG 
 These limitations areofobvious origin. Afew have been mentioned already inpreceding chapters, but since the interest there was merely inthe detection of energy reflected from asingle target and not inover-all radar system design, their implications were not pursued. 4.1. 
 AES–4, no. 1,   pp. 174–180, March 1968. 
 105, pp. 313-317, IEEE (New York) Publication No. 77 CH 1271-6 AES. 
 Ê-/  /9Ê , 
 (21.32), the summation is carried over N + 1 terms. The synthetic antenna length implied by these limits is given by L — NvT. Inasmuch as the summation terms in Eq. 
 GUITY RESOLVERS WORK OVER SEVERAL LOOKS WITHIN A DWELL 4HE FINAL DETECTION OUTPUTS  ALONG WITH THEIR CORRESPONDING UNAMBIGUOUS RANGE  VELOCITY  AND ANGLE MEASUREMENTS  AND THEIR ESTIMATED ACCURACIES  ARE PASSED TO THE MISSION PROCESSOR FOR TRACKING AND OPERATOR DISPLAY {°ÓÊ *1 - 
 Ó£°ÓÓ  2!$!2 (!.$"//+  3.2 BECAUSE THE SPECTRUM OF THE SAMPLING PULSE IS A POOR MATCH FOR THAT OF THE  RECEIVED PULSE )N GENERAL  THE DYNAMIC RANGE OF THE SAMPLING RECEIVER IS TYPICALLY  D"  WITHOUT RANGE TIME  VARYING GAIN 4HE EFFECT OF THE RANGE VARYING GAIN IS TO ENABLE THE LOWER AMPLITUDE SIGNALS FROM TARGETS AT A GREATER RANGE TO BE AMPLIFIED SO AS TO BE ABOVE THE MINIMUM SAMPLING THRESHOLD SIGNAL LEVEL 4HIS IS EQUIVALENT TO A LINEAR RECEIVER WITH A  D" OR MORE DYNAMIC RANGE 3IGNAL AVERAGING OR INTEGRATION OF THE SAMPLES CAN INCREASE THE EFFECTIVE SENSITIVITY BY THE AMOUNT OF AVERAGING AND THIS CAN BE TYPICALLY  TO  D" 4HE RATIO OF THE PEAK TRANSMITTED SIGNAL TO THE MEAN RECEIVER NOISE LEVEL CAN BE UP TO  D" 4HE ANTENNAS THAT CAN BE USED WITH TIME 
 44] CLUTTER 125 How can alow-flying plane betracked across aradar map filled with “permanent” echoes? The only basis that isknown foradistinction between the echoes from aparticular target and equally strong echoes from itsimmediate surroundings isthemotion, ifany, ofthetarget relative toitssurround- ings. 1The reflection ofawave byamoving object gives rise toasignal asreceived inthe neighborhood ofthe (stationary) transmitter, which differs slightly infrequency from theoutgoing wave. This isthefamiliar doppler effect. 
 Formation of Sum and Difference Patterns . Consider the problem of how to form  sum and difference beams with prescribed low sidelobes in a PAR with sub-arrays.  A strategy is to apply a tapering at element level (i.e., in the analogue receiving sec - tion where one attenuator is generally available per element; thus one taper function  is available to achieve reasonable low sidelobes for both sum and difference beams). 
 11.6a. The gap between the stationary and rotating parts ofboth conductors issituated at theend ofanopen-ended quarter-wave coaxial line. As was mentioned in Sec. 
 The  radar senses target displacement from the antenna axis that shifts the spot off of the  center of the focal plane by measuring the resultant unbalance of energy received  in the four horns. This is accomplished by use of microwave waveguide hybrids to  subtract outputs of pairs of horns, providing a sensitive device that gives signal out - put when there is an unbalance caused by the target being off axis. The RF circuitry  for a conventional four-horn square feed (see Figure 9.2) subtracts the output of  ch09.indd   3 12/15/07   6:06:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 21, pp. 49-53, 83, August, 1978. ·. 
 STATE SWITCH SEEMS TO BE  THE SWITCHING MECHANISM THAT  SHOULD BE CONSIDERED INITIALLY WHEN  DESIGNING A TRANSMITTER MODULATOR -ODULATORS CAN BE CLASSED AS EITHER LOW POWER OR HIGH POWER  DEPENDING ON HOW THE TUBE IS MODULATED )F THE TUBE HAS A GRID  A SMALL AND RELATIVELY INEXPENSIVE TYPE OF MODULATOR CAN BE  USED  BUT GRIDS USUALLY ARE NOT FEASIBLE WITH HIGH POWER TUBES ! WIDELY USED SWITCHING ELEMENT FOR LOW 
 OF 
 If the  likelihood ratio l,,(t)) is sufficicrltly I;~rge, it would be reasonable to conclude that the siprial  was indeed present. Thus detection rnay be accomplished by establishing a threshold at the  out put of a receiver which conlputes the likelihood ratio. The selection of the proper threshold  level will dcpc~ld upor1 tltc statistical dctectiotl criterioti used and by the probabilities of error  desired and their relative importance. 
 The large doppler shifts at millimeter wavelengths, however, can sometimes result  in the echo signal being outside the receiver bandwidth, which complicates the receiver design.  Also, the large doppler frequencies at millimeter wavelerigths cause the blind speeds of MTI  radars to appear at lower velocities than at microwaves, an undesirable property.  Thus, a frustrating paradox of the millimeter-wavelength region is that some of its  claimed good points are also its weaknesses. 
 Thus the Butler network  is a manifestation of the FFT. The antenna equivalent of the conventional Fourier transform is  the Blass beam-forming network illustrated by Fig. 8.26. 
  
 (12) It can be seen that the selection of his crucial in determining the performance of the proposed sidelobes suppression method and it will be discussed below in detail. 4. Parameter Design Optimization of the performance of the proposed method is based on three criteria: 4.1. 
  '& !'(   " ) %#&                            .   ")34!4)# 2!$!2   ÓÎ°£Î !CCORDING TO %ASTON  THE 30!352 DESIGN WAS DRIVEN BY COST A   NMI DETEC 
 The abscissa ofthehiTI curve ofFig. 16.22 shoul,i be divided by~. Use ofMTI may thus entail noaverage loss.. 
 30, pp. 1417-1419, September, 1959.  52. 
 The exploration of the microwave region for radar  application became the responsibility of the Radiation Laboratory, organized in November,  1940, under the administration of the Massachusetts Institute of Technology.  In addition to the developments carried out in the United States and Great Britain, radar  was developed essentially independently in Germany, France, Russia, Italy, and Japan during  the middle and late thirties.12 The extent of these developments and their subsequent military  deployment varied, however. All of these countries carried out experiments with CW wave  interference, and even though the French and the Japanese deployed such radars opera­ tionally, they proved of limited value. 
 75, pp. 356-370, March 1987. 37. 
 Lynch, J. O. Pearson, and T. 
  1TANP    =   1   COSP   ;1   )TANP    =  4HE #/2$)# ALGORITHM TAKES ADVANTAGE OF THIS RELATIONSHIP TO APPROXIMATE AN ARBI 
     PP n  ' 6 4RUNK AND * $ 7ILSON  h#ORRELATION OF $& BEARING MEASUREMENTS WITH RADAR TRACKS v IN  )%%% )NT 2ADAR #ONF  ,ONDON    PP n. n°£*ÕÃiÊ «ÀiÃÃÊ,>`>À  V >iÊ,°Ê ÕVvvÊ  ÞÀÊ7°Ê/iÌi ,OCKHEED -ARTIN -3 n°£Ê  /," 1 /"  ! PULSE COMPRESSION RADAR TRANSMITS A LONG PULSE WITH PULSEWIDTH  4 AND PEAK POWER  0T  WHICH IS CODED USING FREQUENCY OR PHASE MODULATION TO ACHIEVE A BANDWIDTH    " THAT IS LARGE COMPARED TO THAT OF AN UNCODED PULSE WITH THE SAME DURATION 4HE  TRANSMIT PULSEWIDTH IS CHOSEN TO ACHIEVE THE SINGLE 
 sameasthesignals(t)forwhichthematched filterwasdesigned (thatis,thenoiseisassumed negligible), theoutputwouldbetheautocorrelation function. Theautocorrelation function of arectangular pulseofwidthrisatriangle whosebaseisofwidth2r... Efficiency ofnonmatched filters.Inpractice thematched filtercannotalwaysbeobtained exactly.Itisappropriate, therefore, toexamine theefficiency ofnonmatched filterscompared withtheidealmatched filter.Themeasure ofefficiency istakenasthepeaksignal-to-noise ratiofromthenonmatched filterdividedbythepeaksignal-to-noise ratio(2E/No)fromthe matched filter.Figure10.2plotstheefficiency forasingle-tuned (RLC)resonant filteranda rectangular-shaped filterofhalf-power bandwidth B,whentheinputisarectangular pulseof widthr.Themaximum efficiency ofthesingle-tuned filteroccursforBr;.:::::0;4,Thecorrespond­ inglossinsignal-to~noise ratiois0.88dBascompared withamatched filter.Table10.1lists Table10.1Efficiency ofnonmatched filterscompared withthematched filter LossinSNRcompared Inputsignal Filter Optimum Brwithmatched filter,dB Rectangular pulse Rectangular 1.37 0.85 Rectangular pulse Gaussian 0.72 0.49 Gaussian pulse Rectangular 0.72 0.49 Gaussian pulse Gaussian 0.44 0(matched) Rectangular pulse One-stage, single-tuned circuit 0.4 0.88 Rectangular pulse 2cascaded single-tuned stages...:',;~.0.613 0.56 Rectangular pulse 5cascaded single-tuned stages. 
 Natlal Rrsrurch  Laboratory, Washington, D.C. (unpublished manuscript), 1948.  73. 
 Thus the element spacing must not be larger than a  half wavelerlgth if the beam is to be steered over a wide angle without having undesirable  graling lobes appear. Practical array antennas do not scan +90°. If the scan is limited to  -!: 60". 
 MATCHED MIR 
 181. The Ohio State  University, Columbus, Ohio, May, 1960. (Reprinted in ref. 
 Zawadzki60 argues, however, that other factors contribute far more to the variability of precipitation rate than does the drop-size distribution. He states, therefore, that dual-parameter estimation techniques are not likely to be successful in many cases. Wilson and Brandes57 state that cumulative pre- cipitation measurements with radar, in storm situations, can be expected to be accurate to a factor of 2 for 75 percent of the time. 
 The noise figure is commonly expressed in decibels, that is, 10 log F,. The term noise  factor is also used at'times instead of noise figure. The two terms are now synonymous. 
 TRAFFIC CONTROL  MILITARY  GROUND 
 I EE, vol. 93, pt IHA, pp. 69-78, 1946. 
 From orbital altitude, scatterers on the surface far  from nadir may generate strong backscatter that appears at the same radar range as  the signals reflected from depth, as suggested in Figure 18.20. The problem is com - pounded with increasing altitude and by the fact that at the long wavelengths required  for deeper penetration, the size constraints on a spacecraft-mounted antenna dictate  that the illumination pattern will have little or no directivity. Processing over groups  of returns to reduce the effective width of the beam can be helpful. 
 PUTE 3.2 FOR A TARGET IS GENERALLY HIGHER THAN THE NET LOSS  ,# USED TO COMPUTE #.2  IN %Q   ,4 INCLUDES LOSSES  SUCH AS ECLIPSING AND RANGE GATE STRADDLE  DO PPLER FILTER  STRADDLE  #&!2  AND GUARD BLANKING  THAT ARE APPLICABLE TO RESOLVABLE TARGETS BUT NOT  TO DISTRIBUTED CLUTTER 4HE TARGET 3.2 REPRESENTS THE ENVELOPE  )1  FOR A LINEAR DETECTOR OR  )    1  FOR A SQUARE 
 44/23, 25 March 1944 (TNA AIR 65/91) [15] Performance of A.S.V. Mk. III in Wellington and Halifax aircraft, C.C.D.U. 
 HIGH 8"2 IS THE WORLDS LARGEST 8 
 Thus, by  using two prf's which are alternated every lO pulses (one-half beamwidth), aircraft targets will  usually appear in at least one filler free from rain except for a small region (approximately 30  knots wide) when the target's radial velocity is exactly that of the rain.  Interference from other radars might appear as one large return among the ten returns  normally processed. In the MTD, an interference eliminator compares the magnitude of each  of !he 10 pulses against the average magnitude of the ten. 
 These curves are theoretical contours of constant radar coverage. The radar height is assumed  to be 200 ft above the curved earth. Curve 1 represents the locus of the geometrical line of sight  as defined by Eq. 
 50. Senf, 11. R.: Electro~iic Antenna Scanning, Proc. 
 If, for example, the  bandwidth of the IF amplifier were 1 MHz and the average false-alarm time that could be  tolerated were 15 nlin, the probability of a fdse alarm is 1.1 1 x lo-'. From Eq. (2.24) the  threshold voltage necessary to achieve this false-alarm time is 6.45 times the rms value of the  noise voltage. 
 TRACKING CIRCUITRY IS ALSO USED FOR ACQUIRING A DESIRED TARGET 2ANGE TRACKING REQUIRES NOT ONLY THAT THE TIME OF TRAVEL OF THE PULSE TO AND FROM THE TARGET BE MEASURED BUT ALSO THAT THE RETURN IS IDENTIFIED AS A TARGET RATHER THAN NOISE AND A RANGE 
 ABSORBING MATERIALS ACTUALLY SOAK UP RADAR ENERGY  ALSO REDUCING THE ENERGY REFLECTED BACK TO THE RADAR (OWEVER  THE APPLICATION OF ABSORBERS IS ALWAYS EXPENSIVE  WHETHER GAUGED IN TERMS OF NONRECURRING ENGINEERING COSTS  LIFETIME MAINTENANCE  OR REDUCED MISSION CAPABILITIES 4HE TWO METHODS OF ECHO CONTROL ARE DISCUSSED IN 3ECTION   AND A COLLECTION OF FOUR STEALTHY PLATFORMS IS SURVEYED THERE 3EVEN "ASIC %CHO -ECHANISMS  &IGURE  ILLUSTRATES SEVEN BASIC ECHO SOURCES  THAT MIGHT BE FOUND ON A TYPICAL AIRBORNE TARGET !LL DEPEND IN VARYING DEGREE ON THE  &)'52%     %XAMPLES OF SEVEN BASIC ECHO 
 Since it is difficult to change the spac- ing between antennas, the displacement is set by the design speed and PRF limits. Then the PRF is varied during operation to maintain the proper alignment. If the antenna is not aligned with the flight path and if d is not equal to V8Tp9 then an error occurs between A1 and A2 as shown in Fig. 
 An alternative method of shaping the beam in one plane is shown in Fig. 6.3c, in which the surface itself is no longer a paraboloid. This is a simpler construction, but since only the phase of the wave across the aperture is changed, there is less control over the beam shape than in the parabolic cylinder, whose linear array may be adjusted in amplitude as well. 
 Azimuth angle J 9b” 1!40” 2;0” 6“ Fm.13.46.—Resolved-e.weep PPI using amplifiers.. 538 THE RECEIVING SYSTEM—INDICATORS [SEC. 13.17 sweeps. 
 TIAL COMPUTATIONAL COMPLEXITY HOWEVER  AS PROCESSORS BECOME MORE SOPHISTICATED  THIS LIMITATION IS DISAPPEARING ! SIMPLER  FASTER VERSION OF 2-! IS THE  #HIRP 
 As an alternative, the GBSAR can achieve continuous and repeated monitoring of a region and feedback monitoring information in real time. In view of the above advantages, GBSAR has become one of the important means for deformation monitoring of dams’ walls, buildings and slope [ 7–10]. The conventional GBSAR system scans the scenes along the linear rail. 
 The product  of the first two factors represents the power per unit area returned to the radar antenna.  Note that the radar cross section of a target, s, is defined by this equation . The receiving  antenna of effective area Ae collects a portion Pr of the echo power returned to the radar. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.74  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 Scattering: Targets and Clutter. 
 19, pp. 92-97, February, 1946.  63. 
 When we speak of antenna gain in relation to the radar equation, we shall usually  mean the maximum gain G, unless otherwise specified. One of the basic principles of antenna  theory is that of reciprocity, which states that the properties of an antenna are the same no  matter whether it is used for transmission or reception.  The antenna pattern is a plot of antenna gain as a function of the direction of radiation. 
 Measurement oftarget bearing was made possible bythe development ofradio techniques onwavelengths short enough topermit theuse ofhighly directional antennas, sothat amore orless sharp beam ofradiation could beproduced byanantenna of reasonable physical size. When thepulses aresent outinsuch abeam, echoes will bereceived only from targets that lieinthe direction the beam ispointing. Ifthe antenna, and hence the radar beam, isswept orscanned around the horizon, the strongest echo will bereceived from each target when thebeam ispointing directly toward thetarget, weaker echoes when the beam ispointed alittle toone side ortheother ofthetarget, and noecho atallwhen itispointing inother directions. 
 Normally, alltubes are biased tocutoff; therefore, when apositive pulse of100 volts isapplied tothe “trigger in” point (Fig. 10.33), plate current starts toflow inT2,inducing afurther positive voltage onthe grid ofTj.Onceregenerative action has commenced, the input trigger has nofurther effect; theplate current increases rapidly until limited by the eP-ip characteristic ofTz.Asi,increases, ePdecreases until itnears the screen potential; from there on,i,increases only slowly, thus pre ducing arelatively flat-topped wave,. 372 THEMAGNETRON ANDTHEPULSER[SEC. 
 A mathematical model of low-frequency amplitude noise of a typical aircraft is  given by  A fB B f2 2 20 12( ).=+ (9.4) where  A2(f) = (fractional modulation)2/Hz   B  = half-power bandwidth, Hz   f = frequency, Hz The value of B falls typically between 1.0 Hz and 2.5 Hz at X band, with the larger  aircraft at the higher values because of the larger reflectors, such as engines, spread  out along the wings. These reflectors with the greater separation contribute to the  higher frequencies because their relative range change is large for a given angular  movement of the target. A2(f) is the modulation power density such that the spectrum  may be integrated over any frequency range to find the total noise power within a  frequency band of interest. 
 DRIVEN  FEATURES  THE MEAN OCEAN  SURFACE IS A DIRECT EXPRESSION OF THE LOCAL GRAVITY GRA 
 6",Ê"Ê- 
 SEC. 10.10] LINE-TYPE PULSERS 377 Inlarge radar equipments, itisoften desirable toseparate pulser and r-funits byconsiderable dktances. The pulse transmission cable neces- sary insuch cases has been standardized atanimpedance level of50 ohms. 
 ERAGE "ECAUSE TERRAIN HEIGHT IS ESTIMATED THROUGH AN ELEVATION MEASUREMENT  ANGLE ACCURACY IS CRITICAL 4HE RANGE COVERAGE  ALTHOUGH SHORT  REQUIRES MULTIPLE OVERLAPPING BEAMS AND MULTIPLE WAVEFORMS /NE METHOD FOR CALCULATING TERRAIN HEIGHT  IS SHOWN IN  &IGURE  )T CONSISTS OF MEASURING THE CENTROID AND EXTENT OF EACH INDIVIDUAL BEAM POSITION OVER MANY PULSES AND ESTIMATING THE TOP OF THE TERRAIN IN EACH BEAM  AS SHOWN IN THE FIGURE 4HE CALCULATION IS SUMMARIZED IN %Q   03 #3$ 0RI IRII I R  rª «­ ¬­££ \\   2 EPOWERRECEIVED¹ ¹ º­ »­ 
 CIRCULAR ;2= AND LEFT 
 Internal reflections  may also be accounted for, and the phase of internally reflected rays should be adjusted  according to the electrical path lengths traversed within the body material. The net  RCS should then be computed as the coherent sum of the surface reflection plus all  significant internal reflections. Equation 14.8 fails when one or both surface radii of  ch14.indd   20 12/17/07   2:47:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 VARYING DOPPLER SHIFT !VERAGING OVER TIME WOULD RESULT  IN A DOPPLER SHIFT TENDING TO  ZERO #LEARLY  THIS IS OF  NO VALUE TO THE OPERATOR WISHING TO COMPENSATE FOR IONOSPHERIC MOTION AND HENCE TO RETRIEVE A MEANINGFUL ESTIMATE OF TARGET RADIAL VELOCITY !S A SECOND EXAMPLE  CONSIDER THE SITUATION WHERE AN ATMOSPHERIC GRAVITY WAVE !'7  IS PROPAGATING THROUGH THE IONOSPHERE IN THE VICINITY OF THE CONTROL POINT IONOSPHERIC REFLECTION POINT  WHILE A TARGET IS BEING TRACKED 4HE IONOSPHERE IS ONLY ^  IONIZED AT THE ALTITUDES OF INTEREST TO (& RADAR  BUT WAVES IN THE NEUTRAL GAS  UNDER THE RESTORING FORCE OF GRAVITY  TRANSFER THEIR MOTION TO THE FREE ELECTRONS VIA COLLISIONS !S THE DISTRIBUTION OF ELECTRONS DEFINES THE hREFLECTING SURFACEv EXPERIENCED BY THE RADAR SIGNALS  THE APPARENT BEARING AND RANGE OF THE TARGET WILL FLUCTUATE AS THE IONOSPHERIC hREFLECTING SURFACEv UNDULATES IN RESPONSE TO THE !'7 4HIS UNDULATION IS KNOWN AS A TRAVELING IONOSPHERIC DISTUR 
 Cutrona, L. J.: Synthetic Aperture Radar; chap. 23 of "Radar Handbook," M. 
 NOISE SPECTRAL  DENSITY AS SHOWN IN &IGURE  !LL OSCILLATOR NOISE CONTRIBUT IONS ARE ASSUMED TO BE  COMBINED INTO THIS ONE CURVE 4HE SINGLE 
 Unlike the planar array, the circular symmetry ensures that mutual  coupling between elements is always the same as the beam scans in azimuth.  The truncated cone has similar properties to the cylindrical array, and might be utilized  instead of the cylinder when the beam is to be scanned in elevation as well as azimuth. The  conical surface as a radiating structure for a conformal array is also of interest since missiles  are sometimes of this shape. 
 SIGMA ARCHITECTURES PROVIDE POTEN 
 A 9-bit AID converter therefore has a maximum diicri-  mination of 1 out of 511 levels; or approximately 54 dB. (Equation (4.12) on the other hand,  predicts 52.9 dB for 9-bit quantization.)  In the above it was said that the addition of the Q channel removed the problem of  reduced sensitivity due to blind phases. This is different than the blind speeds which occur when  the pulse sampling appears at the same point in the doppler cycle at each sampling instant, as  shown in Fig. 
 0  -20  3  & a  & -30 - - U  %  m g --.to .. V ' --I-T ---1- I I  XPhoenix  Phoenix  tx---- Desert  Arizona mountoin~us  N J morshbnd  I)elowor~ noy +,A  L LHH  -60 ----Lrl I I I I I I 1 (11  1" 3" 5" 10" 30" 60" 90.  Grazing angle  (dl 0 Phoenix X. 
 The PRFs are chosen to have a common submultiple frequency \ITU. If the transmitted-pulse trains are compared in a coincidence detector, the common submultiple frequency is obtained. Similarly, if the received gates are compared in a coincidence detector, the same submultiple frequency shifted in time by the target range delay Tr is obtained. 
 Rec. vol. 5, pt. 
 For example, clock jitter results in errors in the sampled output of an ADC, as shown  in Figure 25.19. In addition, real ADCs also add internal jitter, or aperture uncertainty ,  which must be taken into account.6 If the errors in the effective sampling instant intro - duced by these jitters are uncorrelated, a reasonable approximation, the RMS sample- time jitter they introduce, tJ, is  t t tJ J J = + ( ) ( )( ) ( ) ADC CLOCK2 2  where tJ(ADC) and tJ(CLOCK)  are the RMS sample time jitters introduced by the ADC and  the clock, respectively. A sinusoidal input signal of amplitude A and frequency f is expressed as  v(t) = Asin(2p  ft)  which has derivative  dv(t)/dt = A2p  fcos(2p  ft)  The maximum error due to jitter occurs at t = 0, when the derivative of the signal  is at its peak, or  dv(0)/dt = A2p  f  The RMS error voltage, Ve, produced by an RMS sample time jitter, tJ, is given by  Ve = A2p  f tJ  FIGURE 25.19  RMS jitter vs. 
 Chan, T.; Kuga, Y.; Ishimaru, A. Experimental studies on circular SAR imaging in clutter using angular correlation function technique. IEEE T rans. 
 Changes in the configuration  after production, therefore, are likely to impair the mission capabilities of the vehicle.  If considered an option in the control of RCS, shaping must be included in the concep - tual design of the vehicle well before any production decisions are made. Furthermore,  shaping is not very effective for bodies that are not electrically large. 
 The wave spectrum which provides the primary oceanographic description of the sea surface appears in several forms. If the time history of the surface elevation is monitored at a fixed point, the resulting time series may be processed to provide a frequency spectrum S(f) of the surface elevation, where S(f)df is a measure of the energy (i.e., square of the waveheight) in the frequency interval between / and / + df. Wave spectra have been measured in the open ocean primarily for gravity waves down to wavelengths of about 1 m. 
 He employed this type of computation to study the effects of various amounts and kinds of integration, different detector (demodulator) types, losses incurred by "collapsing" one spatial coordinate on the radar display, and various other effects. His results are presented as curves for probability of de- tection as a function of the ratio of the actual range to that at which the signal- to-noise ratio is unity, on the assumption that the received-signal power is in- versely proportional to the fourth power of the range. Since this proportionality holds only for a target in free space, application of Marcum's results is sometimes complicated by this mode of presentation. 
 134. Nicholls~R. B.:Advances intheDesignofFosterScanners, RADAR-77, Oct.25-28,1977,London, lEEConference Publication no.105.pp.401-404, available fromIEEE.NewYork,77CHI271-6. 
 BASED DESIGNS 0ULSE COMPRES 
 InChap.2thereceiver detection criterion wasbasedonthe methods ofMarcum andSwerling. Relationships between threshold levels,probabilities of detection andfalsealarm,signal-to-noise ratio,andnumberofpulsesintegrated wereobtained usingasamodelareceiverwiththefollowing characteristics: (1)theenvelope ofthereceiver noiseattheoutputoftheIFfilterwasdescribed bytheRayleigh probability densityfunction (pdf);(2)theenvelope detector hadeitheralinearorasquare-law characteristic; (3)the integrator consisted ofalinearaddition ofthepulsesinthevideoportionofthereceiver; and. 486 INTRODUCTION TO RADAR SYSTEMS  (4) the detection decision was determined by whether or not the receiver output crossed a  threshold that depended on the desired probability of false alarm. 
 This behavior is said to be due to the  stronger backscatter from vertically oriented structures (trees, buildings, crops) as the grazing  angle approaches zero. Other reported measurements at low grazing angles of heavily wooded,  rolling hills typical of New England show a0 at these angles to be unaffected by changes in  season or weather. 39  There also exists much experimental data of the cr0 of crops such as corn, soybeans, milo,  alfalfa, and sorghum.48-53 The radar backscatter depends not only on the type of crop, and  frequency, but also on the state of its growth, the moisture content of the soil, and the time of  day. 
 1.13  1.4 Radar Frequenc ies  .................................................  1.13  HF (3 to 30 MHz)  ...............................................  1.15  VHF (30 to 300 MHz)  ......................................... 
 Experimental measurements of the operator's ability to detect signals on an A-scope  showed the integration-improvement factor to be n1'2, or 1.5 dB per doubling of the number of  pulses integrated. 31 This is less than predicted for an ideal postdetection integrator. It was also  found that the operator's detection capability was maximum when Bt ::::::: 1, where B = IF  bandwidth and t = pulse width, as is consistent with the analysis of Sec. 
 The distance and bearing of one point to another on the display can  be determined, normally by use of a specific menu item and appropriate control of the  display cursor. The actual implementation of EBLs, VRMs, and offset measurements is  often effected by a common graphical tool, which is used to position and drag lines and  circles across the display by means of the cursor. Many mariners find the use of ship- referenced parallel index (PI) lines to be highly useful. 
 %& FIGHTER IS SHOWN WITH A PROTECTIVE COVER OVER THE ARRAY IN &IGURE  4HE !%3! IS SHAPED AND CANTED UPWARD TO AID IN SOME MODES AND TO MINIMIZE REFLECTIONS TO ENEMY RADARS #HAPTER . x°Ó  2!$!2 (!.$"//+  4HIS CHAPTER ADDRESSES  WHAT SIGNALS ARE EMITTED AND  WHY THEY ARE NEEDED IN A  -ULTIFUNCTIONAL &IGHTER !IRCRAFT 2ADAR -&!2  4HE  WHY BEGINS WITH TYPICAL MIS 
 Depending on details, this condition is valid only for  qsq less than about 45°, since, for a given crossrange resolution, as qsq increases, LSA  increases, and the condition becomes no longer valid. Spotlight  SAR.  Spotlight SAR (sometimes called “spot SAR”) is used to obtain  a relatively fine-resolution image of a known location or target of interest. 
 BEAM AMPLIFIER %ACH TIME A PULSE IS TRANSMITTED  ITS PHASE IS DIFFERENT FROM THE PHASE OF PREVIOUS PULSES 4HAT IS  ITS PHASE IS RANDOM FROM PULSE TO PULSE 4O DETECT THE DOPPLER FREQUENCY SHIFT FOR -4) PROCESSING  THE PHASE CANNOT CHANGE IN A RANDOM MANNER AT THE RECEIVER FROM PULSE TO PULSE 4HIS LIMITATION IS OVERCOME BY TAKING A SAMPLE OF THE RANDOM PHASE OF EACH TRANSMITTED PULSE AND USING IT TO RESET THE PHASE OF THE LOCAL OSCILLATOR IN THE RECEIVER TO MATCH THE PHASE OF THE TRANSMITTED SIGNAL 4HIS IS SOMETIMES CALLED  COHERENT ON RECEIVE 'ENERALLY  THE -4) IMPROVE 
 18–21. 41. J. 
 RANGE DETECTION TO SEVERAL THOUSAND  Sn FOR SHORTER 
 Blevis. 8. C.: Rain Effects on Radomes and Antenna Reflectors," Design and Construction of Large  Steerable Aerials," IEE (London) Conference Pul,/icatio11110. 
 ARI 5205, only installed on some Sunderlands, had a very high-power transmitter with a separate modulator for the broadside mode. Transmission was through the receive arrays and the transmit array was not used. The standardtransmitter was used for homing. 
 D. Roscnherg: Very tligh Freqc~ency  Radiowave Scattering by a Disturbed Sea Surace. IEEE Trc~~ts., vol. 
 VIDES HIGH RESOLUTION IN RANGE AND OBTAINS SUITABLE RESOLUTION IN ANGLE BY USING A  NARROW BEAMWIDTH ANTENNA 3YNTHETIC APERTURE RADAR 3!2   3!2 IS A COHERENT   IMAGING RADAR ON A MOVING  VEHICLE THAT USES THE PHASE INFORMATION OF THE ECHO SIGNAL TO OBTAIN AN IMAGE OF A  SCENE WITH HIGH RESOLUTION IN BOTH RANGE AND CROSS 
 However, the total variation (dynamic range) of the  received signal with target position is not as pronounced with bistatic radar as with monostatic  radar. In bistatic radar. as either D1 or D, decreases, the other increases. 
 ch20.indd   34 12/20/07   1:16:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 
                                    
 Experience has demon- strated that a large antenna should not be built until the element pattern has been verified with a small array. 8 (DEGREES) FIG. 7.22 Experimental //-plane patterns of the center elements of waveguide arrays. 
 PATH BREAKTHROUGH EFFECTS ARE SIMILAR TO THOSE OF A SPOT NOISE JAMMER AND  CAN BE CHARACTERIZED BY AN INCREASE IN THE SYSTEM NOISE TEMPERA TURE  4 S   &N 4O  WHERE  &N IS THE RECEIVER NOISE FIGURE AND  4O    + 3PECIFICALLY  THE AMOUNT OF INCREASE IN  4S  AND HENCE THE AMOUNT OF ATTENUATION  #DP REQUIRED TO REDUCE THE DIRECT PATH SIGNAL  TO THE LEVEL OF 4S  IS   #DP   04 '4 '2 4 K   O   " , K4S    WHERE 04  '4  K  AND K ARE DEFINED WITH %Q   '2 4 IS THE RECEIVING ANTENNA POWER  GAIN IN THE DIRECTION OF THE TRANSMITTER  " IS THE INPUT 2& BANDWIDTH AND  , IS THE  BASELINE RANGE &OR EXAMPLE  IF THE 0"2 EXPLOITS A TYPICAL &- BROADCAST TRANSMITTER LOCATED AT A   KM ,/3 FROM THE RECEIVER   04 '4    K7   K    M  "    K(Z  AND  ,    KM  !SSUMING A FIXED RECEIVING ANTENNA BEAM TAILORED IN ELEVATION AND COVERING A WIDE AZIMUTH SECTOR  WHICH INCLUDES THE TRANSMITTER SITE   ' 2 4 MIGHT BE  D"I !LSO  ASSUM 
 FIRE ECHO AREA OF LONG  THIN BODIES v  )2% 4RANS  VOL !0 
   4AYLOR N     
 26,  no 9, pp. 667- 672, 1976  [Mei] H.H. Meinel, Comme rcial applications of millimeterwaves: history, present status  and future trends, IEEE Trans. 
 The FM waveform in the block diagram of Fig. 11.14 is generated by directly modulating  the high-power transmitter. It is not always convenient to directly modulate a transmitter in  this manner. 
 Wind speed affects the brightness variations and the brightness contrast of the SAR image. With an increased wind speed, the image is brighter and its brightness contrast is higher. Therefore, in future SAR observations of eddies, brightness features due to different radar look directions and wind ﬁeld should be considered while interpreting eddy images. 
 J.W..andJ.W.Tukey: AnAlgorithm fortheMachine Computation ofComplex Fourier Series.Math.Comp..vol.19,pp.297-301, April,1965. 30.Andrews. G.A.,Jr.:Performance ofCascaded MTIandCoherent Integration FiltersinaClutter Environment. 
 Forradarreceivers ofthesuperheterodyne type(thetypeofreceiverusedformostradar applications), thereceiver bandwidth isapproximately thatoftheintermediate-frequency stages.Itshouldbecautioned thatthebandwidth BIIofEq.(2.2)isnotthe3-dB,orhalf-power. bandwidth commonly employed byelectronic engineers. Itisanintegrated bandwidth andis givenby ('IH(f) 12df BII= .-allH(fo) 12(2.3) whereH(f)=frequency-response characteristic ofIFamplifier (filter)andfo=frequency of maximum response (usually occursatmidband). 
 Trapping.  Trapping is an extension of superrefraction because the meteorological  conditions for both are the same. Should the refractivity gradient decrease beyond the  critical gradient, the radius of curvature for the wave will become smaller than the Earth’s  curvature. 
 The echoes from the flash points at the sides of the base weaken as the aspect angle moves away from nose-on incidence, and the sidelobes seen at +13° in Fig. 11.10 are actually due to an interaction between the two flash points across the shadowed side of the base. (The sidelobes disappear when a pad of absorber is cemented to the base.8) The flash point at the far side of the base disappears when the aspect angle moves outside the backward half cone, but the near flash point remains visible, and its echo decays with increasing aspect angle. 
 (From Ward and  Slirader,53 Courtesy IEEE.)  However, when the MTI improvement factor is not great enough to reduce the clutter  sufficiently.~the clutter residue will appear on the display and prevent the detection of aircraft  targets whose cross sections arc larger than the clutter residue. This condition may be pre­ vented hy selling the limit level L relative to the noise N, equal to the MTI improvement  factor I; or L/N = /. If the limit level relative to noise is set higher than the improvement  factor. 
 Required sensitivity values range from –38 dBm  (dB milliWatt with respect to the isotropic) to –60 dBm. ESM is the most complex  system and usually comprises the capability to produce a picture of the complete  electronic order of battle in its deployment area and alert function. This kind of  system is able to detect and analyze emitter waveforms and scanning patterns. 
 As  the amplitude is tapered, the gain drops, the beam broadens, and the sidelobes may  be reduced. It is important for the antenna designer to choose an efficient and realiz - able illumination function that provides low sidelobes at a minimum loss in gain. For  low-sidelobe radars, the Taylor illumination69,70 for the sum patterns and the Bayliss  illumination71 for the difference patterns have almost become an industry standard. 
 GE- 22, pp. 165–169, 1984. 107. 
 Such brightness variations are, as a matter of fact, a modulation of the normalized radar cross section, which is also referred to as NRCS. The eddy spiral presents itself due to its higher or lower NRCS than the background. Along an eddy spiral, whether it gets brighter or darker, can be quantiﬁed as the NRCS contrast between values along the spiral and surrounding it. 
 Itcanbedefinedsimilarly tothedefinition of. 226 INTRODUCTION TO RADAR SYSTEMS  directive gain in Eq. (7.2), except that the denominator is the net power rlccrprrd by the  antenna from the connected transmitter, or  4n(maximum power radiatedlunit solid angle) G = --  net power accepted by the antenna  An equivalent definition is  maximum radiation intensity from subject antenna G = --- - - - - -. 
 This gives complete independence to radar- and AIS-derived data, therefore,  enhancing integrity checking. 22.6 USER INTERFACE From the user’s point of view, the most visible and important change in marine radar  from its early days has been the development of processor-based display technology.  In particular, modern well-designed displays are viewable over a wide variation of  ambient lighting; they make effective use of color and give easy and clear access to the  radar image and associated data. 
 (2.40)], and a class  of pdf's called the " K-distributions" based on modeling the clutter as a finite two-dimensional  random walk." The Weibull pdf has also been examined for modeling sea c~utter.~~.'~ It is a  two-parameter pdf, like the log normal, but is intermediate between the Rayleigh and the  log normal. In the Weibull clutter model the amplitude probability density function of the  voltage v out of the envelope detector is  p = a n 2) exp 1 -In 2(,::)']  where a is a parameter that relates to the skewness of the distribution (sometimes called the  Weibull parameter), and v, is the median value of the distribution. By appropriately adjusting  its parameters, the Weibull can be made to approach either the Rayleigh or the log-normal  distributions. 
 The transmitter of a typical ground-based air surveillance radar might have an average power of several kilowatts. Short-range radars might have powers mea- sured in milliwatts. Radars for the detection of space objects (Chap. 
 M. C. Wicks, W. 
 &- WAVEFORM $IGITAL PULSE COMPRESSION HAS DISTINCT FEATURES THAT DETERMINE ITS ACCEPTABILITY  FOR A PARTICULAR RADAR APPLICATION $IGITAL MATCHED FILTERING USUALLY REQUIRES MULTIPLE OVERLAPPED PROCESSING UNITS FOR EXTENDED RANGE COVERAGE 4HE ADVANTAGES OF THE DIGI 
 Misra, S. S. Rana, V . 
 By combining the signals in processing, this method permits  synthesizing equivalent transmitted polarizations  with any ellipticity and orientation. A commonly used way to describe the polarization characteristics of a target is the  polarization signature .32 This consists of two three-dimensional graphs. For the first  graph, called copolarized, one uses the components of the received signal that are the  same  as the transmitted-signal polarization. 
 Figure 6.8\vas also pro- duced byvideo mapping, thefinal display being aB-scope. This method has thevery great advantage that the map iscorrectly correlated with theradar display regardless ofthedegree ofoff-centering,. 224 THEEMPLOYMENT OFRADAR DAT-A [SEC. 
 J. Povejsil, R. S. 
 WAVE FREQUENCIES ARE POWER AMPLIFIERS  LOW 
 If the a priori probability p(SN) can be considered constant, the computation of  the a posteriori probability is equivalent to multiplying the received signal y(t) by the signal  wavefor111 s,(r) aritf iritcgr;lting with respect to tirlie. 'This is tlle same process performed by the  cross-correlation receiver (Sec. 10.3) and is equivalent to the operation of a matched filter  (Sec. 
 OPERATIONALv 4HE RESULTING TERMS ARE   FIXED hSTANDARDv OFF 
 One reason is that the bandwidth over which the higher-frequency radar can  operate is greater, thus causing the jammcr to spread its available power over a greater  number of megahertz. Also, the antenna gain can be greater at the higher frequencies, a factor  often favoring the radar when confronted with jamming, as seen by Eqs. (14.28) and (14.30). 
 T. Ulaby, “The active and passive microwave response to snow parameters,  part I: wetness,” J. Geophys. 
 Curves of constant relative speed are also curves of constant doppler shift. The equation of such a curve is v2 - v2 x2 - y2 + h2 = O Vr This is a hyperbola. The limiting curve for zero relative speed is a straight line perpendicular to the velocity vector. 
 TRACK FOOTPRINT IS ABOUT  KM  WHICH IS THE RESULT OF ONBOARD COHERENT DOPPLER PROCESSING 4HIS STRATEGY REDUCES THE IMPACT OF OFF 
 -Ê"Ê 
 From the simple observation of the ﬁrst left singular vector of the matrix Utwo parameters can be extracted: the antenna beam pattern in azimuth and the phase history of the azimuth reference to be used in the focusing procedure. To select the proper parts of the two singular vectors for the focusing procedure a threshold was selected aiming at retaining the portion of the signal with amplitude greater than a given percentage of its peak value. In this paper, the 10% was selected. 
 KNOWN  AND FOLLOW VERY SIMILAR TRAJECTORIES OVER  SUBSEQUENT REPEAT PERIODS )T FOLLOWS THAT THE SPACE 
 This response is caused by the first-order mixer product H-L, which originates mainly from the square-law term in the power- series representation. All other lines on the chart define spurious effects arising from the cubic and higher-order terms in the power series. To simplify use of the chart, the higher input frequency is designated by H and the lower input fre- quency by L. 
 Muhleman, “Radar scattering from venus and the moon,” Astron. J. , vol. 
 54. Blanchard, D. C.: Raindrop Size Distribution in Hawaiian Rains, J. 
 It is required to operate  fro111 50 to 1000 knots at attitudes of 225" pitch and +45" roll of the aircraft, at an altitude  of 40.000 ft over water. The rrns accuracy is claimed to be within 0.13 percent $0.1 knots of  the true prourid velocity.  3.5 MULTIPLE-FREQUENCY CW  RADAR'^.'^ 63  Although it has been said in this chapter that CW radar does not measure range, it is possible  undcr sorllc circurns~:t~lccs to do so by measuring the phase of the echo signal relative to the  phase of tile trarlsrnitted signal. 
 Less  attcntuation is applied to tile higher frequencies, where the echo signals are weaker.  The echo signal from an isolated target varies inversely as the fourth power of the range,  AS is well known from the radar equation. With this as a criterion, the gain of the low-  frcqueticy amplifier sliould be made to increase at the rate of 12 dB/octave. 
 BUILT MEANS TO CORRECT FOR IONOSPHERIC OR ATMOSPHERIC PROPAGATION DELAYS 3EASATS !LTIMETER  3EASATS WAS THE FIRST TO USE FULL DERAMP o PULSE COMPRESSION   WHICH OPENED THE WAY FOR THE VERY SMALL RANGE RESOLUTION REQUIRED FOR MANY OCEANOGRAPHIC APPLICATIONS 4HE DERAMP TECHNIQUE DESCRIBED BELOW  HAS BEEN ADOPTED BY ALL RADAR ALTIM 
 Any use is subject to the Terms of Use as given at the website. Airborne MTI.  AIRBORNE MTI  3.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 actual displacement along the line-of-slight varies with elevation angle. This effect is  more pronounced at higher aircraft speeds and higher radar frequencies. 
 68, pp. 654–666, June 1980. 124. 
   (& /6%2 
 The true spectrum may be approx - imated by a gaussian spectrum,  H f e e Gf Vd x ( ) ( = = ≈−  −  1 2242 2 σθ λσpm pmθ θ) (3.5) G4(q ), the two-way power pattern of the antenna, is 0.25 when q  = qa /2, where qa is  the half-power beamwidth, which can be approximated by l/a, a being the effective  horizontal aperture width. Thus,  eV ax −  =1 22 0 25σpm.  or  σpm=0 6.V ax  (3.6) where Vx and a are in consistent units. 
  E 
 Variations in insertion loss may be  compensated for dynamically with the gain adjustment. The circulator at the high-power side provides an impedance match to the power  amplifier and may be adequate by itself for protecting the receiver. In Figure 13.36,  the module is shown augmented by a switch that causes absorption of power reflected  from antenna mismatches and also gives added protection to the receiver during trans - mission. 
 Sherman, “Monopulse tracking error due to multipath:  Causes and remedies,” in EASCON Rec ., 1971 pp. 175–182. 51. 
 47-50, November, 1975.  70. Gupta, P. 
 The direct results ofspurious triggers oneither theangle data orthesweep triggering were notappreci- able, but loss ofthe trigger occasionally upset the sequencing with unfortunate results. Once theproper chain isbroken, itcanbespuriously started byinterference orbyvideo signals and remain inerror forseveral cycles. Both the indicator sweeps and the azimuth data are then in error, sometimes byasmuch as5°or10°. 
 A .. R. C. 
 RANGE REFLECTING SURFACE  WHICH  IN EFFECT  IS A MEASURE OF THE CROSS 
 43. P. Beckmann, Probability in Communication Engineering , New York: Harcourt, Brace and World,  Inc., 1967, Sect. 
 4(% 
 POWER MODULATOR )N DC OPERATION THE HIGH VOLT 
 Fenn, and F. G. Willwerth, “Phased array antenna calibration and pattern  prediction using mutual coupling measurements,” IEEE Trans. 
        
 SPEED REGION NEAR ZERO DOPPLER (IGH 
 J. Cutrona of the University of Michigan  Willow Run Laboratories, C. W. 
 Although theoutputfluduations ahoutthemeanareconstant, theoutputmeanisnot.A high-pass filterremoves themeanvalueoftheoutput,leavingthefluctuation oftheclutterata constant levelonthedisplay.Thehigh-pass filterisequ~valent toadifferentiation, orto acircuilwithafasltime-constant (FTC).Thenoiseorclutterfluctuations thatappearatthe outputofalogarithmic receiverarenotsymmetrical sincethelargeamplitudes aresuppressed duetothenatureofthelogarithmic characteristic. Tomaketheoutputmorelikethatofa linearreceiver, thelog-FTC mayhefollowed byanamplifier withtheinverseofthelogarith­ miccharacteristic (antilog). Thisrestoresthecontrast ofthedisplayandeliminates thelossin detectability associated withthelogarithmic characteristic. 
 T. Rickard and G. M. 
 Plane Displays Involving Elevation.-One rarely desires toknow theelevation angle oraltitude ofanaircraft target without also requiring itsrange and bearing. Simultaneous azimuth and elevation information can beobtained bytwo-dimensional scanning with asingle antenna, by theV-beam principle (Sec. 6“12), orbytheuseofseparate radar systems scanning respectively inazimuth and inelevation. 
 The earth loses  heat. and its surface temperature falls, but there is little or no change in tlie temperature of the  upper atmosphere. This leads to conditions favorable to ducting, that is, a temperature inver-  slon at the ground and a sharp decrease in the moisture with height. 
 In those radars which  extract the doppler frequency shift, as with a bank of doppler filters, the estimate of the  background Ean be based on both the range and the doppler domains.77 It is also possible to  utilize data from the adjacent angle-resolution cells to establish the threshold.  A common assumption in the design of many CFARs is that the probability density  function of the background noise amplitude is known (usually taken to be gaussian) except for  a scale factor. Clutter, however, is often nonhomogeneous and thus nonstationary, as well as  being of unknown probability density function in some cases. 
 (ILL   ST %D  .EW 9ORK -C'RAW 
 Its sensitivity also car1  approach that of an ideal quantum detector. The photomixing receiver is more complicated  than the direct photodetection receiver and it requires a stable transmitter and local oscillator.  Wlieri tlie target is in motion relative to the radar a large doppler frequency shift occurs which  can place the echo signal outside tlie receiver passband. 
 EXCITER AND THE TRANS 
 The Canadian requirements spanned a variety of applications, from oce - anic surveillance (vessels and oil platforms as well as sea state), land- and sea-ice,  agriculture, and forests, among many others. The sea-ice application had high pri - ority, which drove the choice of polarization. Horizontal was chosen, because that  ‡  It is common in radar remote sensing that their polarizations are abbreviated as an alphabetic pair, in this case  indicating vertical polarization on both transmit and receive. 
 The opposite is generally the case for a pulse doppler radar. Its  pi~lse repetition frequency is usually high enough to operate with unambiguous doppler (no  blinti speeds) but at the expense of range ambiguities. The discussion in this chapter, for the  most part, is based on tile MTI radar, but much of what applies to MTI can be extended to  pulse dol~plcr radar as well. 
 giving stronger signals and  greater ranges than antennas and targets at Iiciglits up to 30 m; wliich is a firrtlicr indication of  effective trapping at thc higlicr frcqucncies.  It was observed that with a large cnougl~ duct more than one mode can be propagated  and there can be more than one antcnna liciglit suitable for low-loss propagation. For  one set of ?(-band data sliowcd tlie minimum attenuation to occirr with an antcnna  height of 2 m. 
 S. Longuet-Higgins and J. S. 
 Clutter echoes, unlike receiver noise, might be cor-  related pulse to pi~lse, especially if the clutter is stationary relative to the radar. Receiver noise  is i~cilally decorrelated ill a tinie equal to l/B, where B = receiver (IF) bandwidth. The decor-  relation time of clutter is usually much greater than this. 
 If these N pulses are integrated without loss as in a perfect  predetection integrator, the total signal-to-noise ratio in the multiple-beam radar just compen­ sates for the lesser transmit gain. Thus the multiple-beam rttdar and the scanning-beam radar  have equivalent detection capability, provided the data rates are the same and integration is  without loss. Data rate is defined here as the revisit time in a scanning-beam radar, and in a  multiple-beam radar it is the time over which the total number of pulses are integrated. 
 In radar, we  must consider both transmitted and received polarimetric signals, so the need for four  magnitudes and two phases. Another way to describe polarimetric signals is to use the matrix of Stokes  parameters:  F=        =+ −I Q U VE E E E E Eh v h v h v022 22 2Re(*) ) Im( )2 E Eh v           (16.27) The individual Stokes parameters I0, Q, U, and V are defined as shown in Eq. 16.27. 
 be compensated ·hy a modest· increase in antenna aperture and/or  additional transmitt~r· power, But:ror·mi:,imum efficiency with CW radar, the reduction in  sensitivity caused by the simple doppler:r~iver with ·zero IF. cannot be tolerated.  The effects of flicker:·noise)ire ·"' -,. 
   e  HTTPWWWEUMETSATINTGROUPSOPSDOCUMENTSDOCUMENTPDF?TM?REV 
 The VA-812E  was also a high-power UHF klystron that had a 20 MW peak power, 25 MHz 1 dB  bandwidth, 40 dB gain, and an average power of 300 kW at a duty cycle of 0.015 and  a 40 µs pulse width. The V A-87E (originally developed by Varian Associates, Inc) is a 6-cavity S-band  pulse klystron that operates from 2.7 to 2.9 GHz, produces a peak power of from 1  to 2 MW, an average power up to 3.5 kW, has a gain of about 50 dB, an efficiency  between 45 and 50%, and a 1 dB bandwidth of 39 MHz. It has demonstrated a mean- time-between-failures of 72,000 hours. 
 NENTS !MPLITUDE NOISE TYPICALLY FALLS INTO A LOW FREQUENCY AND HIGH FREQUENCY REGION OF INTEREST 4HESE CATEGORIES OVERLAP IN SOME RESPECTS  BUT IT IS CONVENIENT TO SEPARATE THE NOISE IN THESE TWO FREQUENCY RANGES BECAUSE THEY ARE GENERATED BY DIFFERENT PHE 
 Requirements onthe antenna pattern were relatively simple. The beamwidth inazimuth had tobeasnarrow aspossible, toafford good resolution oftargets ontheground. The elevation pattern was required togive themost uniform ground coverage possible throughout thenormal flying altitudes: from 1000 to10,000 ft.. 
 344–349. 22. D. 
 23 Regression of average of all 13.8-GHz  cropland data for two years obtained with a microwave  active spectrometer ( after R. K. Moore, K. 
 50. J. Baniak, G. 
 Ignoring the  required amplitude variations still leads to good approximations for forming multiple  beams, by superimposing the various required phase-shifter settings (modulo 2 p ). In  the case of two beams, the aperture phase slope has the average inclination and varies  periodically from 0 to p. Vertical Scan Only. 
 Frank: Array Antennas, chap. I I of Rarlor Mutitlhook, M. I. 
 LEVEL SPACE 
 Ant. & Prop ., vol. AP-8, pp. 
 Within Chapter V  of SOLAS - Safety of Navigation , the requirements for the carriage of navigation  equipment are defined. These vary according to the size and purpose of a ship. All  passenger ships and all ships above 300 gt need to carry at least one radar with  tracking facilities. 
 Rept. 2500,  September 1972. 153. 
 Multiple-delay cancelers have wider clutter rejection notches than  single-delay cancelers. The wider rejection notch encompasses more of the clutter  spectrum and thus increases the MTI improvement factor attainable with a given  clutter spectral distribution. *  Delay is used here to represent an interpulse memory for an MTI filter. 
 The target DoA  is at 0°, the SNR is 0 dB, the JNR is 30 dB. Three curves summarize the system  performance. The dashed line is the array pattern with raised cosine taper: this is  shown for the sake of comparison with the other two curves of the SINR. 
 NANCE PERIODS 3INCE ARRAY COMPONENT FAILURES INDUCE ONLY A GRADUAL DEGRADATION  MAINTENANCE CAN BE PERFORMED ON A PLANNED BASIS /NLINE SYSTEM SENSITIVITY AND PERFORMANCE LEVEL IS CHECKED AND DISPLAYED BY THE PERFORMANCE MONITORING AND FAULT ISOLATION -&)  FUNCTION&)'52%   'ROUND 
 Many nodding-beam-type height finders with ingenious means of beam scanning have been successfully deployed over the years. Two notable examples are the World War II SCI radar and the AN/SPS-8 shipborne radar, both of which used a Robinson-type electromechanical feed to rapidly scan the beam in elevation. The development of higher-frequency microwave technology facilitated elec- trically larger apertures and correspondingly narrower beams, all in convenient physical sizes. 
 the i11dex of rcfractio11 is zero and the waveguide is beyond cutoff The wave  i11cide111 011 the le11s will be completely reflected. In practice, a compromise value of tt between  0.5 and 0.6 is often selected, corresponding to plate spacings of0.557) and 0.625,1. and to power  rcllectio11s at normal i11cidence of 11 and 6.25 percent, respectively (Ref. 
 Equation (2.29)maybeconverted topowerbyreplacing the signalto·rms-noise-voltage ratiowiththefollowing: _.~__=~!~n~_l_~~plitude =J2(rms signalvoltage) =(2signalpower) 112=(25)112 t/tl/2rmsnoisevoltagc rmsnoisevoltage noisepower N WeshallalsoreplaceVi-/2t/Jo byIn(l/Pra)[fromEg.(2.24)].Usingtheaboverelationships, thcprobability ofdetection isplottedinFig.2.7asafunction ofthesignal-to-noise ratiowith theprobability ofafalsealarmasaparameter. Noise%ne06 0.4 :::.0.3 ~ 0.2 0.1 0.......,""-'-_....L......u<.JOO!""'-"'-~CA..L.e.-L----L_o Figure2.6Probability-density function fornoisealone andforsignal-plus-noise. illustrating theprocess of thrc!\hold detection.. 
 pp 274 280. Jan.19.1968.  92. 
 REFERENCES 1.Ridenour, L.N.·:"Radar SystemEngineering," MITRadiation Laboratory Series,vol.I,chap.16, McGraw-Hill BookCo.,NewYork,1947. 2.White,W.D.,andA.E.Ruvin:RecentAdvances intheSynthesis ofCombFilters,IR£Noel.CO/Ill. Record,vol.5,pt.2,pp.186-199, 1957. 
 56. Dinneen, G. P., and I. 
 ANGLE SEA BACKSCATTER v  2ADIO 3CI    VOL   PP n    0 'ERSTOFT  , 4 2OGERS  7 3 (ODGKISS  AND , * 7AGNER  h2EFRACTIVITY ESTIMATION USING  MULTIPLE ELEVATION ANGLES v )%%% * OF /CEANIC %NG  VOL   NO   PP n  *ULY   $ % "ARRICK  h.EAR 
 (Frorrr  11,) I I, ,, I I I (r I Olirr artd Q~reer~.~') 10  Table 2.lb Median cross section (XI.,,) for aspects near nose-on  I  Azimuth angle (degrees)  Flevrttion  angle 0 2 5 7 Azimuth angle (degrees)  Elevation  angle 0 2 5 7  X,, : Transmit left circular polarization, receive left circular (X band). X,, : Transmit left circular  polarization, receive right circular (X band). S,,, : Transmit vertical polarization, receive vertical (S band). 
 A military propeller aircraft such as the AD-4B has a cross section of about 20 m2 at L  band, but a la) m2 cross section at VHF. The longer wavelengths at VHF result in greater  THERADAR EQUATION 41 I I I.­ I I ,/ / Trailing edgeof horizontal toil /I T, I I I I--0--0Peakdue10 Iralingedge dwingo2- 24- 24-Peakdue foleading 2 -edged wing" I'"/'"1". I '.... 
 Range resolution is established by  gating. Once the radar return is quantized into range intervals, the output from each gate may  be applied to a narrowband filter since the pulse shape need no longer be preserved for range   resolution.'^ collapsing loss does not take place since noise from the other range intervals is  excluded.  A block diagram of the video of an MTI radar with multiple range gates followed by  clutter-rejection filters is shown in Fig. 
 A common:radome enclosing the two antennas should be  avoided since it limits the amount of isolation that can be achieved.  72INTRODUCTION TORADAR SYSTEMS thenoisethataccompanies thetransmitter leakagesignalratherthanbyanydamagecaused byhighpower.5Forexample, suppose theisolation between thetransmitter andreceiverwere suchthattomWofleakagesignalappeared atthereceiver. Iftheminimum detectable signal wereto-13watt(100dBbelow1mW),thetransmitter noisemustbeatleast110dB (preferably 120or130dB)belowthetransmitted carrier. 
 IN TESTS AT TWO LEVELS AN OPERATIONAL READINESS  TEST PERFORMED AS PART OF MISSION INITIATION AND A FAULT ISOLATION TEST PERFORMED BY THE MAINTENANCE CREW IN RESPONSE TO AN OPERATOR DEFICIENCY REPORT "OTH TESTS TAKE LONGER AND ARE MORE EXHAUSTIVE )N THE BEST CASE  THE SPECIFIC FLIGHT  LINE OR A FIRST 
 The surface-reflected signal travels a longer path than the direct signal so that it may be  possible in some cases to separate the two in time (range). Tracking on the direct signal avoids  the angle errors introduced by the multipath. The range-resolution required to separate the  direct from the ground-reflected signal is  !!R = 2hah,  R (5.7)  where ha = radar antenna height, h, = target height, and R = range to the target. 
 BEAM ANTENNA MOUNTED ON A ROTATABLE PLATFORM WITH SERVO MOTOR DRIVE OF ITS AZIMUTH AND ELEVATION POSITION TO FOLLOW A TARGET &IGURE  A   %RRORS IN POINTING DIRECTION ARE DETERMINED BY SENSING THE ANGLE OF ARRIVAL OF THE ECHO WAVEFRONT AND CORRECTED BY POSITIONING THE ANTENNA TO KEEP THE TARGET CENTERED #HAPTER . °Ó  2!$!2 (!.$"//+  IN THE BEAM -ODERN REQUIREMENTS FOR SIMULTANEOUS PRECISION TRACKING OF MULTIPLE  TARGETS HAS DRIVEN THE DEVELOPMENT OF THE ELECTRONIC SCAN ARRAY MONOPULSE RADAR WITH THE CAPABILITY TO SWITCH ITS BEAM PULSE 
 TION BEAM STEERING 4HERE ARE TWO PARALLEL RECEIVE CHANNELS DEDICATED TO THE ( 
 The effect can be so great that it can become impossible to track targets at low  elevation angles with a conventional tracking radar. In addition to causing errors in the  elevation-angle tracking, it is also possible for surface-reflected multipath'to introduce errors  in the azimuth-angle tracking; either by "cross-talk" in the radar between the azimuth and  elevation error channels, or by the target-image plane departing from the vertical as when over  sloping land or when the radar is on a rolling and pitching ship.  The surest method for avoiding tracking error due to multipath reflections,via the surface  of the earth is to use an antenna with such a narrow beamwidth that it doesn't illuminate the  surface. 
 In one example of a Luneburg lens 10 concentric spheri­ cal shells are arranged one within the other.54•55 The dielectric constant of the individual shells  varies from 1.1 to 2.0 in increments of 0.1.  Point  source tlE--------1>-------+-~--- Figure 7.21 Luneburg-lens geometry showing rays from  a point source radiated as a plane wave after passage  through the lens. RADAR ANTENNAS 253  The dielectric materials must not be loo heavy, yet they must be strong enough to support  their own weight without collapsing. 
 M. Yale, D. T. 
 A map of soft soils distribution and a map of carbonate belts distribution are obtained from Wuhan municipal commission of urban-rural development and a geological study, respectively [ 47]. Three human factors are considered: groundwater exploitation, subway excavation and urban construction. The data of the three human factors include an ofﬁcial route map of the Wuhan subway system, the groundwater resources regionalization of Wuhan, two high resolution images of the year 2015 and 2017. 
 Higher  frequency radars tend to have narrower antenna beamwidths and larger operating fre - quency bandwidths (5 to 10 percent of radar center frequency) than lower frequency  radars. Thus, main-beam jammers will blank smaller sectors of high frequency radars  than of low frequency radars. In addition, main-beam jamming of a narrow beam  radar tends to provide a strobe in the direction of the jammer, which can be used to  triangulate and reveal the jammer location. 
 For that reason, thediscussion oftl-piral components given here \vill beinmicrowave terms, despite thefart that JITI methods areuseful with radar systems operating atlonger Tvavelrngth. The com- ponents that \rill bedescribed have been chosen toillustrate recent de~-el. opments orthe breadth ofpossibilities, ortosupplement the detailed treatment ~fthe components elselvhere inthe Radiation Laboratory Series. 
 105. R. C. 
 Locke, A. ,S.: "Guidance," D. Van Nostrand Company, Inc., Princeton, NJ., 1955, pp. 
 Their navigational aids had tobeexternal totheaircraft. Atotal complement of8officers and 38enlisted men was required to operate asingle control SCR-584, themajority ofthese men belonging to the organization involved inmaking use oftheradar data. 7.8. 
 132  13 Selected Radar Applications ............................................................................................ 135  13.1 Tracking Radar ............................................................................................................. 135  13.2 Monopulse Radar .......................................................................................................... 
 The selection of the local-oscillator frequency is a bit  different from that in the usual superheterodyne receiver. The local-oscillator frequency .f;F  should be the same as the intermediate frequency used in the receiver, whereas in the conven-  tional superheterodyne the LO frequency is of the same order of magnitude as the RF signal.  The output of the mixer consists of the varying transmitter frequency fo(t) plus two sideband  frequencies, one on either side offo(t) and separated from/b(t) by the local-oscillator frequency  84INTRODUCTION TORADAR SYSTEMS reversed becauseofachangeintheinequality signhdwl:l:nf~ andfJ'anincorrl:ct interpreta­ tionofthemeasurements mayresult. 
 Although the accuracy of simultaneously measuring  time and frequency with a simple pulse-modulated sinusoid was seen to be limited, it is  possible to obtain simultaneous time and frequency measurements to as high a degree of  accuracy as desired by transmitting a pulse long enough to satisfy the desired frequency  accuracy and one with enough bandwidth to satisfy the time accuracy. In other words, the  peak at the center of the ambiguity diagram may be narrowed by transmitting a pulse with a  large bandwidth times pulse-width product (large pa). One method of increasing the bandwidth  of a pulse of duration T is to provide internal modulation. 
 After the change maps are generated, object properties such as area and location are calculated and, based on a user-deﬁned area threshold, insigniﬁcant change areas are excluded from the change maps. The remaining change areas are then overlaid onto the reference image. In the 2CMV image, the areas that exist only in the reference image are colored in cyan and the areas that exist only in the mission image are colored in red. 
 BASED 3!2S  WHICH HAVE BEEN AND WILL CONTINUE TO BE RICH  SOURCES OF QUANTITA 
 Jones, C. C. Kilgus, and J. 
 EQUIVALENT SIGMA 
 TUBE SWITCH OFTEN USED IN A LINE 
 This method isextremely useful when avariable sweep isinvolved, since itavoids thenecessity of‘‘track- ing” two potentiometers. 13.14. B-scope Design.—The essentials forproviding atype Bdisplay have been shown inFig. 
 The wavenumber spectrum associated with S(f) is a function of the two com- ponents of K and is commonly written as W(Kx,Ky). This is called the directional wave spectrum and expresses the asymmetries associated with winds, currents, refraction, isolated swell components, etc. For a given source of asymmetry like the wind, various parts of the spectrum will display different directional behav- iors. 
 50, pp. 2632–2643, November 2002. 147. 
 AP-22, March 1974. 52. W. 
 Resolution is possible since each element of the distributed target has a different relative  velocity. This principle has been used in synthetic aperture radars for ground mapping, inverse  SAR for SO1 and the imaging of planets, and in the scatterometer for measuring the ground or  sea echo as a function of incidence angle.  Internal motions of the target such as the rotation of aircraft engines, vibrations of vehi-  cles, the spinning ofa satellite, or the rotation of antennas can also provide information about  the target. 
 STATE TRANSMITTER 4HE #%! ACHIEVES THESE EFFICIENCIES SINCE THERE IS NO LOSS OF  EFFI 
   %,%#42/.)# #/5.4%2 
 È°ÎÓ  2!$!2 (!.$"//+  IN COMPLEX FORM IN %Q  )GNORING ANY MIXER INSERTION LOSS OR LOSS ASSOCIATED WITH  THE )& SPLIT  THE COMPLEX REPRESENTATION OF THE MIXER OUTPUT IS GIVEN BY %Q  )DEAL LOW 
 III in Sunderland Aircraft, CCDU Trial 43/45, August 1943 (TNA AIR 65/40)Airborne Maritime Surveillance Radar, Volume 1 4-32. [20] ASV Mk. VIC in Sunderland Mk. 
   4HIS 3 
 (Courtesy Westinghouse Electric Corporation.) . shaping must incorporate a steep skirt at the horizon to allow operation at low elevation angles without degradation from ground reflection. A vertical array can produce much sharper skirts than a shaped dish of equal height can, since a shaped dish uses part of its height for high-angle coverage. 
 Receiver Input Noise Level.  Because many radar systems include low-noise  amplifiers prior to the input of the receiver, it is important to understand and specify  the noise level at the receiver input. This noise level is set by the antenna noise tem - perature and its total effective noise gain or loss. 
 Usually therearefourbasicaspectstoautomatic detection: (I)theinte§ration ofthe pulsesreceived fromthetarget;(2)thedetection decision; andthedetermination ofthetarget location in(3)rangeand(4)azimuth. Sometimes thereisalsoincluded inautomatic-detection circuitry themeansformaintaining aconstant falsealarmrate(CFAR). Thisisdiscussed separately inthenextsection. 
 Microwave imaging from sparse measurements for near-ﬁeld synthetic aperture radar. IEEE T rans. Instrum. 
 The reflected energy therefore  will have a polarization perpendicular to the wires of the parabolic reflector and will pass  through with negligible attenuation. The twist reflector can be made relatively broadband. An  attractive feature of this antenna configuration is that the beam can be readily scanned over a  wide angle by mechanical motion of the low inertia planar reflector. 
 VI, looking into wind, crosswind and downwind; Left hand column, discriminator OUT; Right hand column discriminator IN [ 17].Airborne Maritime Surveillance Radar, Volume 1 4-31. sensitivity by about 2.5 dB. Indeed, it was reported that the detection range against a small target was slightly increased, alth ough there was an accompanying increase in the range of sea returns. 
 Î°Ó  2!$!2 (!.$"//+  WHERE TS IS THE SCAN TIME AND  7 IS THE SURVEILLANCE VOLUME COVERAGE REQUIREMENT PROD 
 MENT IN WHICH THE SIGNAL FROM THE TRANSMITTER IS ATTENUATED A KNOWN AMOUNT AND USED TO CHECK THE RECEIVER GAIN "Y COMPARING THE OUTPUT FROM THE ATTENUATED TRANSMITTER SIGNAL WITH THAT RECEIVED FROM THE GROUND  THE SCATTERING CROSS SECTION MAY BE DETERMINED WITHOUT ACTUALLY KNOWING THE TRANSMITTED POWER AND THE RECEIVER GAIN 4HE CALIBRATIONS SHOWN IN &IGURE  ARE INCOMPLETE WITHOUT KNOWING THE  ANTENNA PATTERNS AND ABSOLUTE GAINS 3INCE ACCURATE GAIN MEASUREMENTS ARE DIFFICULT  ABSOLUTE CALIBRATIONS MAY BE MADE BY COMPARING RECEIVED SIGNALS WITH PROPER RELA 
 POINT  2ADIX 
 14. Dicke. R.H.: Object Detection System. 
 Target classification. The characteristic echo signal from a distributed target when observed  by a short pulse can be used to recognize one class of target from another.  ECCM. 
 Electronic Warfare (EW) and ELectronic  lNTelligence (ELINT) experts specialize in the study of these  pulsed signals. Pulse characteristics provide valuable  information a bout the type  of radar producing a signal and  what its source might be - sailboat, battleship, passenger  plane, bomber, missile, etc.     Figure 2. 
 (This is somewhat like  an optical analog of tlie radar itself.) Since it is undesirable to operate with the image focused  OTHER RADAR TOPICS ~23 deviating fromastraight line.Thesedeviations mustbesensedandpropercompensation appliedtothereceived~signalphase so"asto"straightenuut"" thesynthetic antenna.19The required phasecorrection isafunction ofrangewiththemorerapidcorrections required at steepdepression angles.Thusbothmotioncompensation andantenna stabilization areneces­ sarytoachievetheresolution inherent inanSAR. Opticalprocessing.t"-3.92 Inasynthetic aperture radarthecoherent echosignalsSnfromeach rangeintervalmustbestored,withoutlossofphase,overthetimeintervalrequired toformthe synthetic aperture. Anamplitude weighting Wnisusuallyappliedtoeachofthesignalstotaper the"illumination" ofthesynthetic aperture soastoachievelowersidelobes thangivenbya uniform illumination. 
 A. Ausherman, A. Kozma, J. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters.  SOLID-STATE TRANSMITTERS  11.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 In this relationship, IMAX is the maximum open channel current, VDGB is the gate- drain breakdown voltage, VP is the pinchoff voltage, and VK is the knee voltage. 
 Limiting results in a loss of only a fraction of a decibel for a large number of pulses  integrated, provided the limiting ratio (ratio of video limit level to rms noise level) is as large as  2 or 3.10 Other analyses of bandpass limiters show that for small signal-to-noise ratio, the  reduction in the signal-to-noise ratio of a sine-wave imbedded in narrowband gaussian noise is  n/4 (about l dB).53 However, by appropriately shaping the spectrum of the input noise, it has  been suggested54 that the degradation can be made negligibly small.  Collapsing loss. Ir the radar were to integrate additional noise samples along with the wanted  signal-to-noise pulses, the added noise results in a degradation called the collapsing loss. 
 The open centerElevation Amle ~ FIG. 6.6.—Stretched PPI. Tw&mile gridisshown bydashed lines. 
 W.. and F. K. 
 The estimated rheological parameters can be provided as a reference index for the interpretation of long-term highway deformation and the stability control of subgrade construction engineering. Keywords: deformation model; time series deformation; rheological parameter; highway 1. Introduction Stability control of highways built on a soft clay subgrade is one of the key technical problems for highway subgrade engineering. 
 An Introduction to Radar   ........................................ 1.1  1.1 Description of Radar  ...............................................  1.1  Radar Block Diagr am  ......................................... 
 5.7d.  A block diagram of the amplitude-comparison-monopulse tracking radar for a single  angular coordinate is shown in Fig. 5.8. 
 BASED RADARS THAT GUIDE AIRCRAFT TO A LANDING  IN SOME TYPES OF WEAPON 
 In this event, the regulator pile must beremoved and the damaged disk replaced. One fundamental defect ofthecarbon-pile regulator isthelack ofany means forinsuring uniform voltage distribution across the stack. Some carbon junctions may betightly+d.c mated, with low voltage drop; I:IlkCarbon.pile others may beloose, with high voltage voltage drop. 
 13  Converting the Equation  ................................ ................................ ................................ 
 Poker Flat ISR station. Available online: http://isr.sri.com/madrigal/ (accessed on 8 February 2018). 26. 
 spurious quantizatio11 lobes, similar to grating lobes. The peak-quantization lobe relative to the  main beam, when the phase error has a triangular repetitive distribution is  . 1 b I Peak quantization o e = -28 2 (8.32)  This applies when the main beam points close to broadside and there are many radiating  elements within the quantized phase period. 
 Back-end or IF attenuation is often used to adjust the gain of the receiver to  compensate for receiver gain variations due to component variations where receiver  noise figure degradation cannot be tolerated. 6.7 FILTERING Filtering of the Entire Radar System.  Filtering provides the principal means  by which the radar discriminates between target returns and interference of many  types. 
 TOR  IT HAS SELDOM BEEN USED BECAUSE IT REQUIRES A MUCH LARGER CAPACITOR BANK TO LIMIT DROOP  AN ARC IN THE TUBE REQUIRES A CROWBAR THAT INTERRUPTS OPERATION FOR A FEW SECONDS INSTEAD OF ONLY FOR A SINGLE PULSE  AND THE ADJACENT RADARS MIGHT INJECT ENOUGH 2& POWER INTO THE RADAR ANTENNA AND BACK TO THE TRANSMITTER TO TURN ON A DC OPERATED #&! AT THE WRONG TIMES 4HERE HAS BEEN AT LEAST ONE EXAMPLE IN THE PAST WHERE A MAJOR RADAR SYSTEM ORIGINALLY DESIGNED WITH #&!S BASED ON DC OPERATION HAD TO HAVE ITS DC OPERATED #&!S REPLACED DURING THE MIDDLE OF ITS DEVELOPMENT WITH #&!S THAT USED CONVENTIONAL PULSE MODULATORS !T THE BEGINNING OF THE  TH CENTURY  THE  SOLID 
 REFERENCES 1. Skolnik, M. L: Fifty Years of Radar, Proc. 
  .KM OR     
 Tanner, and W. Wilson, “ARMAR: An airborne  rain mapping radar,” J. Atmos. 
 Also. a significant portion of the energy radiated by the feed would not intercept the  paraboloid and would be lost. The lost" spillover" energy results in a lowering of the overall  efficiency and defeats the purpose of the uniform illumination (maximum aperture efficiency). 
 The images of real airborne data based on the different methods. ( a) The inertial navigation information; ( b) the basic MAM method; ( c) the IMAM method; ( d) the EMAM method. $PSOLWXGH G%  Figure 12. 
 In free  space, the electromagnetic wavefront from an isotropic radiator spreads uniformly in  all directions from the transmitter. Multipath Interference and Surface Reflection.  When an electromagnetic  wave strikes a nearly smooth large surface, such as the ocean, a portion of the energy  is reflected from the surface and continues propagating along a path that makes an  ch26.indd   4 12/15/07   4:52:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The angle noise phenomenon affects all types of tracking radars but is mainly of  concern for tracking radars where precision target location is needed. To aid in visu - alizing why angle noise affects any radar-type angular-direction-sensing device, the  echo signal propagating in space was analyzed, showing that the angle noise is pres - ent in this propagating energy as a distortion of the phase front. Theoretical plots of  a distorted phase front from dual sources compare very closely with photographs of  the phase front of the radiating surface ripples in the ripple-tank experiment with dual  vibrating probes.37 All radar angle-sensing devices sense, by one means or another, the  phase front of the signal and indicate the target to be in a direction normal to the phase  front. 
 22. Gallop. M.A., Jr .• and L. 
 Analog product detectors used to extract I and Q baseband components have been  replaced in many systems by digital down-conversion techniques. In this approach, the  complex envelope sequence is evaluated by digital signal processing of A/D converter  samples at the final IF output of the receiver, rather than by separate A/D conversion of  baseband analog I and Q components.51–53 Digital down-conversion is advantageous  because performance is not limited by amplitude and phase imbalances that exist in  analog product-detection hardware. Figure 8.27 illustrates two digital signal-processing approaches to providing the  matched filter for a pulse compression waveform. 
   *ANUARY   $ECLASSIFIED   $ # 3CHLEHER   %LECTRONIC 7ARFARE IN THE )NFORMATION !GE   .ORWOOD  -! !RTECH (OUSE     PP n  n  3 (OVANESSIAN   )NTRODUCTION TO 3YNTHETIC !RRAY AND )MAGING 2ADARS  $EDHAM  -! !RTECH  (OUSE    #HAPTER   * #URLANDER AND 2 -C$ONOUGH   3YNTHETIC !PERTURE 2ADAR 3YSTEMS AND 3IGNAL 0ROCESSING   .EW 9ORK 7ILEY  3ONS    PP n  n  * +OVALY   3YNTHETIC !PERTURE 2ADAR  $EDHAM  -! !RTECH (OUSE    PP n  n   n  " ,EWIS  & 2 +RETSCHMER  AND 7 7 3HELTON   !SPECTS OF 2ADAR 3IGNAL 0ROCESSING   $EDHAM   -! !RTECH (OUSE    PP n  - 2ADANT  $ ,EWIS  AND 3 )GLEHART  h2ADAR SENSORS v 5#,! 3HORT #OURSE .OTES  *ULY   $ ,YNCH  * / 0EARSON  AND % 3HAMASH  h0RINCIPLES OF -ODERN RADAR v %VOLVING 4ECHNOLOGY  )NSTITUTE 3HORT #OURSE .OTES  *UNE   * &RICHEL AND & #OREY  h!.!0' 
 Sensors 2019 ,19, 2161 (a)( b) Figure 2. The integration time and azimuth resolution of P-band sliding spotlight mode as function ofkω.(a) Integration time. ( b) Theoretical azimuth resolution. 
 W. Guinard, “Radar detection of oil spills,” presented at Joint Conf. Sensing of Environmental  Pollutants, AIAA Pap. 
  
 POLE FILTER 4HUS  THE RECEIVER PASSBAND RESPONSE FALLS OFF AT  D" PER DECADE FROM THE BREAK FREQUENCY AT  K(Z AS SHOWN&)'52%  3TRAIGHT 
 63.Albersheim. W.J.:Elevation Tracking Through ClutterFences.IEEETrailS,vol.AES-3,no.6 (EASTCON Suppl.), pp. 366-373. 
 The velocity error ΔV(10 m/s )and the acceleration error ΔA/parenleftbig−0.1 m/s2/parenrightbig are added in the imaging process. Here are the examples of point targets C1, C2, and C3 in Figure 5to illustrate and compare the estimation results of the Doppler parameters of the different methods. Figures 9and 10show the two-dimensional imaging results and the azimuth impulse responses of targets by the different methods with the velocity and the acceleration errors, respectively. 
 vol. 22.  pp. 
 ARRAYS ARCHITECTURE CAN  BE REPRESENTED BY A MATRIX  4 HAVING A NUMBER  - OF COLUMNS EQUAL TO THE NUMBER  OF SUB 
  DATA FOR ITS ROUTINE OPERATIONS  WHICH REQUIRE MORE THAN  FRAMES OF DATA PER YEAR 3INCE THE 3!2 IS THE ONLY 2!$!23!4 
 Beacons ofthe synchronous sort just described have been variously called “radar beacons,” ‘~responder beacons,” “racons,” and “trans- ponders,’’ there being noessential distinctions among these terms. The discussion hereis confinedto such beacons since other free-running types, more like ordinary radio beacons, appear tobeless useful inconjunction with radar sets. From the free-running type, only the bearing can be determined. 
 ERROR DETECTOR  ASSUMED TO BE A PRODUCE DETECTOR  HAS AN OUTPUT   \\\\ \\EK $3 33COSQ    WHERE \ E \ IS THE MAGNITUDE OF THE ANGLE 
 ON ECHOES ARE ATTRIBUTABLE TO SUR 
 2012 ,48, 121–122. [ CrossRef ] 24. Moore, T.G.; Zuerndorfer, B.W.; Burt, E.C. 
 Shock Vib. 2015 ,2015 , 390134. [ CrossRef ] 33. 
 SIDELOBE ANTENNAS ARE REQUIRED  THE NUMBER OF BITS INCREASES &OR LOW SIDELOBE ANTENNAS      OR  BITS MAY BE REQUIRED !S THE NUMBER OF BITS INCREASES  BOTH COST AND LOSS OF THE DIODE PHASE SHIFTERS ARE ALSO INCREASED &OR ACTIVE ARRAYS  THE PHASE SHIFTER LOSSES ARE NOT OF SIGNIFICANCE BECAUSE THEY OCCUR PRIOR TO THE POWER AMPLIFIER ON TRANSMIT AND AFTER THE LOW 
 Patent2,435,615, Feb.10,1948. 61.Skolnik, M.I.:AnAnalysis ofBistaticRadar,Appendix, IRETrans.,vol.ANE-8,pp.1927,March, 1961. 62.Hastings, C.E.:Raydist: ARadioNavigation andTracking System, Tele-Tech, vol.6,pp.30-33, 100-103, June,1947. 
 The effects of atmospheric absorption have been noted  above in connection with millimeter-wave clutter, but at very low grazing angles,  the ray paths joining the radar to the surface become very sensitive to refractive  inhomogeneities in the atmospheric boundary layer. Over distances approaching and  FIGURE 15.17  Sea clutter produced by rain splashes alone on a calm surface   (20 dB corresponds to about s  0 = −40 dB) ( from Hansen69) ch15.indd   24 12/15/07   6:17:09 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The same motor that provides the conical-scan rotation of the antenna beam also drives  a t\\ .J-phase reference generator with two outputs 90° apart in phase. These two outputs serve  as a reference to extract the elevation and azimuth errors. The received echo signal is fed to the  receiver from the antenna via two rotary joints (not shown in the block diagram). 
 It should be noted that ultrawideband antennas fall into two classes, those that  radiate a reasonably short impulse with low time sidelobes and fundamentally pos - sess a linear phase-frequency characteristic. The alternative class of antennas, such as  log periodics, have wideband frequency characteristics but nonlinear phase-frequency  characteristics. Essentially, the latter class will cause the different frequency compo - nents of an impulse to be radiated at different times, hence dispersing the impulse. 
 NOISE RATIO ARE INDUCED IN THIS CASE  IT TURNS OUT THAT  .    AND 2'0/ IS DECLARED  INACTIVE 7HENEVER THE JAMMER IS NO  LONGER IN THE TARGETS LINE 
 Against clutter returns which have the same spectrum as the transmitted radar pulse, the matched filter is no longer optimum, but the potential improvement in the output signal-to-clutter ratio by designing a modified optimized filter is usually insignif- icant. When the duration of the transmitted radar signal, whether CW or a repetitiveGROUNDCHAFF SEA RAINWOODED HILLS10-KNOT WIND WOODED HILLS40-KNOT WIND1 INTERNAL CL DUAL CANCELLER (dB) . crv (METERS PER SECOND}^ FIG. 
 Heating caused by frequencies penetrating the  interior of the body can be of concern ·because the sparsity or sensory nerves may make it  imperceptible. Higher frequencies absorbed at or close to the surface of the 6ody are more  likely to be perceived than interior heating.  There have been few authenticated incidents where radiations have bei:n the cause of  biological damage in humans. 
 ch20.indd   48 12/20/07   1:16:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 
 BAND DESIGN  DEVELOPED BY  .ORTHROP 
 , since radars can be, and have been, operated at frequencies outside either end of this range.  Skywave HF over-the-horizon (OTH) radar might be at frequencies as low as 4 or 5 MHz, and  groundwave HF radars as low as 2 MHz. At the other end of the spectrum, millimeter radars  have operated at 94 GHz. 
 Often optical and SAR images of the same target region do not look the same to a human  observer. ( Courtesy of SciTech Publishing, Inc .) ch17.indd   19 12/17/07   6:49:25 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Hibbs: Organ-pipe Radar Scanner, Electronics, vol. 25, pp. 126-127, May,  1952. 
 Figure 8.7 c shows a reflection-array- compression (RAC) approach10 that essentially doubles the achievable pulse length for  the same crystal length. In an RAC, the input and output transducers have a broad band - width. A frequency-sensitive grating is etched on the crystal surface to reflect a portion  of the surface-wave signal to the output transducer. 
 F. G. Bass and I. 
 7.45. REFERENCES  1. J. 
 Although the basic theory of radar wave propagation may be well understood, accurate  quantitative predictions are not always easy to obtain because of the difficulty in acquiring the  necessary knowledge or the environment in which the radar operates. In some respects, the  prediction of propagation phenomena is like predicting the weather. Quite often the radar  system designer must be content with only a qualitative knowledge or" average" propagation  eITecls. 
 C . 
 BANDWIDTH PRODUCT OF THE ,&- WAVEFORM IS MUCH GREATER THAN UNITY 4"    4HE FILTER MATCHING LOSS FOR 4AYLOR WEIGHTING IS GIVEN BY +LAUDER ET AL  AS   ,&MM MN 
 Ofall the practical modifications perhaps the  easiest to follow is the application of a biasing voltage  to the gas-filled tube. These small voltages are applied  to encourage the gas gap to ionize as soon as the trans-  mitter ‘mark’ begins, and ensure that the receiver side  of the feeder is safely switched off.  The gas gap, therefore, enables pulses of energy to be  . 
 If the 271 radians is changed in a time llf, , then the  rate of change of phase is 2nL. Thus the linear phase change can be accomplished if  the frequency difference between the LOs at the mixers of adjacent elements is j;.  By multiplying the summed output of all the element mixers with a periodic sampling  train of narrow gating pulses, a particular portion of space is observed. 
 SYNCHRONOUS REPEAT PERIOD IS THE ONLY SENSIBLE STARTING POINT !N ALTIMETERS REVISIT PERIOD IS TEN DAYS OR MORE  IN CONTRAST  TO TIDES WITH APPROXI 
 The switch selects either the vertical or the horizontal input component or combines  them with a 90° relative phase for circular polarization. This feed does not provide  optimum sum- and difference-signal E fields because the sum horn occupies space  desired for the difference signals. Generally, an undersized sum-signal horn is used  as a compromise. 
 TYPE ANTENNA  SQUARE OR CIRCULAR CROSS 
 Proceedings for 1941.  This method of creating pulses is used in many radar  systems, but an even more popular circuit is that of the  ‘multi-vib,’ or multi-vibrator, to give its full ttle, an  honour seldom, I may say, accorded it by radar mech-  anics. The multi-vib is much older than radar. 
 Themostrealisticmethodforobtaining theradarcrosssectionofaircraftistomeasure theactualtargetinflight.Thereisnoquestion abouttheauthenticity ofthetargetheing measured. Anexample ofsuchafacilityisthedynamic radarcross-section rangeoftheU.S. NavalResearch Laboratory.3o RadarsatL,S,CandXbandsilluminate theaircrafttargetin flight.Theradartrackdataisusedtoestablish theaspectangleofthetargetwithrespecttothe radar.Pulse-to-pulse radarcrosssectionisavailable, butforconvenience inpresenting the datathevaluesplottedusuallyareanaverageofalargenumberofvaluestakenwithina10by 10°aspectangleinterval. 
 Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 22.8  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 The IMO International Convention for the Safety of Life at Sea (SOLAS)9 is an  established and accepted set of principles and rules aimed at ensuring that ships meet  certain requirements to enhance both safety and protection of the environment. The  member governments (flag States) of IMO have agreed that SOLAS requirements  are embodied within their national maritime laws and regulations. 
 The latter group  are normally known as vessel tracking service (VTS†) radars. Radars are available for  leisure craft, fishing vessels and merchant ships, and all operate either in the 3 GHz  or 9 GHz bands. Many navies also use standard or specially modified CMR for navi - gational purposes. 
 CALLY DISPLACING THE ANTENNA PHASE CENTER ALONG THE PLANE OF THE APERTURE 4HIS IS REFERRED TO AS THE DISPLACED PHASE CENTER ANTENNA $0#!  TECHNIQUE  n )N ADDITION  SOME FORMS  OF SPACE 
 DELAY NETWORKS HAVE TO BE INTRODUCED TO SUPPLEMENT  THE PHASE SHIFTERS #ONFORMAL  !RRAYS  0HASED ARRAYS MAY CONFORM TO CURVED SURFACES AS  REQUIRED  FOR EXAMPLE  FOR FLUSH 
 118).. SEC. 11.2] COAXIAL LINES 393 WhyaMatched Line?—The fraction ofthe incident power reflected tothe source from asection oftransmission line ofgiven VSWR is Power reflection coefficient =[(VSWR) –1]’ [(VSWR) +1]2(3) For theusual upper design limit ofVSWR =1.5,itisseen that thepower reflection loss isonly 4percent, or0.3db,surely not serious. 
 ABLE CANCELLATION  WHICH  IN TURN  IS SET BY THE RECEIVERS ANALOG 
 The choice of  the correct polarization offers, among other advantages, the possibility of suppressing disturbances  (weather).  Thus precipitation disturbs less with circular polarizat ion.  The knowledge around the  evaluation of polarization characteristics is called Radar polarimetry. 
 VARYING  FRACTAL SURFACE v -ICROWAVE AND /PTICAL 4ECH ,ETT  VOL   NO   P     3 (AYKIN  h2ADAR CLUTTER ATTRACTOR IMPLICATIONS FOR PHYSICS  SIGNAL PROCESSING AND CONTROL v   )%% 0ROC 2ADAR 3ONAR .AVIG  VOL   NO   P   !UGUST   2 (ARRINGTON  4IME 
 -PreSt·11r ,md future. IEE (London)  Conf. Publ. 
 The first sweep reads the signal on the storage tube. The next sweep is written on the same  space and generates the difference between it and the first sweep, as required for two-pulse  MTI cancellation. Two storage tubes are required: one to write and store the new sweep, the  other to subtract the new sweep from the old sweep. 
 This is not so with the second edition.  The current literature is quite large; and, because of the limitations of.space, only a milch  smaller proportion of what is available could be cited.  In addition to changes in radar technology, there have been changes also in style and  nomenclature. 
 Astanin and Kostylev, Ultra-wideband Radar Measurements Systems , IEE Radar Sonar  Navigation and Avionics Series, Vol. 7, London: IEE Books, 1997, Chap. 1. 
 TIME CORRECTION OF TRACKING LAG 4HERE ARE A LARGE VARIETY OF TRACKING 
 The (sin t/l)N composing function is well suited for reconstructing the pattern. Its value at  a particular sample point is unity, but it is zero at all other sample points. In addition, the  (sin t/l)N function can be readily generated with a uniform aperture distribution. 
 2.5 DEFINITIONS The IEEE Standard Radar Definitions15 provide useful definitions for many of the  quantities needed to quantify MTI and MTD performance, but in some cases, the  vagueness of the original definition and the lack of distinction between performance  against distributed clutter versus point clutter returns have led to ambiguous interpre - tations of several terms. In this section, the major definitions will be reviewed and  annotated to attempt to clarify some of these potential ambiguities. For each term, the  IEEE definition, when available, will be quoted along with a subsequent discussion. 
 Blake, “The effective number of pulses per beamwidth for a scanning radar,” Proc. IRE ,   vol. 41, pp. 
 DESIGNED MONOPULSE RADAR 4HE ORIGINAL FOUR 
     "LOCKAGE,OSS   $ $B M¤ ¦¥³ µ´    WHERE $B AND $M ARE THE DIAMETER OF THE BLOCKAGE AND REFLECTOR  RESPECTIVELY 4HE EFFECTIVE FEED HORN DIMENSIONS CAUSING BLOCKAGE MAY BE DIFFERENT FROM THE  PHYSICAL DIMENSIONS )F THE WALLS ARE NOT TAPERED  SUCH AS SHOWN IN &IGURE   THE  EFFECTIVE SIZE OF THE BLOCKAGE HOLE CAN BE LARGER THAN THE PROJECTED OBSTACLE AREA  &)'52%   'RAPHICAL REPRESENTATION OF SPILL 
 164 65 Representation ofthe Horizontal Plane. 167 6,6 Plane Displays Involving Elevation 171 6.7 Three-dimensional Displays. 174 6,8 Error Indicators. 
 CANCELLATION OF PHASE  NOISE BASED ON CORRELATION RESULTING FROM THE TWO 
 Rotary spark gaps, ‘‘trigatrons,” series gaps, hydrogen thyratrons, and mercury thyratrons have allbeen used asnet- work switching devices. Each has itsfield ofapplication. Each switch islimited inone ormore ofthefollowing respects: (1)poor precision of firing, (2)low maximum pulse rate, (3)short lifeonlong pulses, (4)nar- row operating range ofvoltage, (5)occasional erratic firing, (6)inefficient cathode, and (7)unnecessary complication. 
 24.8 SPECTRUMUSE The waveforms that can be effective for HF radar are in general similar to those used at the higher frequencies and are selected for similar reasons. However, the transmission path is dispersive, and waves experience polarization rotation with frequency; because of these effects, bandwidths are limited to the order of 100 kHz without correction. The more restrictive constraint on emissions is that of noninterference to and by other services. 
 Microwaves Conf ., London,  October 22–24, 1980, pp. 103–108. 35. 
 Hence, for a ground-based system that is limited by scan rate, one should improve the compensation pattern rather than use a higher-order MTI canceler. However, airborne systems are primarily limited by platform motion and require both better cancelers and compensation for operation in a land clutter environment. In the sea clutter environment the system is usually dominated by the spectral width of the velocity spectrum or platform motion rather than scan- ning. 
 22. Gao, Y.; Xing, M.; Zhang, Z.; Guo, L. Ultrahigh range resolution ISAR processing by using KT-TCS algorithm. 
 52–63,  April 1998.  7. R. 
 4.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 where  Ai = IPP weight, 0 ≤ i ≤ N−1  N = number of IPPs in CPI  sc = standard deviation of clutter spectrum  K = filter number ( K = 0 is the DC filter)  T = interpulse period Clutter-transient Suppression.  When (1) the PRF is changed for multiple- PRF ranging, (2) the slope is changed in linear FM ranging, or (3) the RF carrier is  changed, the transient change in the clutter return may cause degradation unless it is  properly handled.38 Since the clutter is usually ambiguous in range in a pulse doppler  radar, the clutter power increases at each interpulse period (IPP) as clutter return is  received from the farther ambiguities, until the horizon is reached. This phenomenon  is called space charging . 
 In the spring of 1940, when some of the airborne radar team moved to Worth Matravers, others from the team, including Keith Wood, Robert Hanbury-Brown, Gerald Touch and Roy Hearsum moved to the Royal Aircraft Establishment (RAE)at Farnborough [ 7]. The RAE were responsible for aircraft research and in 1940 its Radio Department was tasked with overseeing the engineering and production of 1.5 m ASV and AI systems.Airborne Maritime Surveillance Radar, Volume 1 1-2. TRE were closely involved not only in the design of the radars but most importantly in assessing radar performance through trials and providing advice to the RAF on the operation and maintenance of the new equipment. 
 PARABOLIC IONOSPHERE WITH NO  -AGNETIC &IELD v 2ADIO 3CIENCE  VOL   PP n    2 * .EWTON  0 , $YSON  AND * ! "ENNETT  h!NALYTIC RAY PARAMETERS FOR THE QUASI 
 One of the first CFAR receivers to be described in the literature used the output of a post-  detection integrator (low-pass filter) to estimate the average noise. This was then applied as a  feed-forward signal to control the threshold level to maintain the false-alarm rate  constant.' The noise had to remain constant for a time corresponding to the total number  of pulses returned from the target. Another CFAR technique is the hard limiter, sometimes  called the Dickefi~.'~-~~ This consists of a broadband IF filter followed by a hard limiter and  a narrow-band matched filter. 
 Dellwig, and B. C. Hanson: Experiments on the Radar Backscatter of  Snow. 
 Straiton. and C. 0. 
 Measurements of attenuation for field crops25'26 and grasses27 show that most of the return is from the upper layers, with some contribution by the soil and lower layers if the vegetation is not very dense. Most of the signal returned from trees is usually from the upper and mid- dle branches when the trees are in leaf,28"32 although in winter the surface is a major contributor to the signal. 12.3 THEORETICALMODELSANDTHEIR LIMITATIONS Descriptions of a Surface. 
 PATH FEED 
 PATTERN PHASED ARRAY ANTENNAS !S A RESULT  METHODS FOR PLACING  NULLS IN THE DIRECTION OF THE INTERFERENCE IN THE PHASED ARRAY RADIATION PATTERNS HAVE BEEN THE SUBJECT OF MUCH RESEARCH n %ITHER DETERMINISTIC RADIO FREQUENCY NULLING  OR ADAPTIVE NULLING CAN BE USED TO PLACE NULLS IN THE ANTENNA PATTERN IN THE DIRECTION OF THE INTERFERING SOURCE )F THE LOCATION OF THE INTERFERING SOURCE IS STATIONARY AND THE DIRECTION OF THE INTERFERER  IS KNOWN  A DETERMINISTIC 2& NULL CAN BE PLACED IN THE ANTENNA PATTERN AT THAT SPECIFIC DIRECTION $ETERMINISTIC ANTENNA PATTERNS WITH NULLS STEERED IN SPECIFIC DIRECTIONS CAN BE ACHIEVED BY MODIFYING THE WEIGHTS AT EACH ELEMENT 4HESE MODIFIED WEIGHTS CAN BE EITHER THE AMPLITUDE AND PHASE OF EACH ELEMENT OR ONLY THE PHASE OF EACH ELEMENT  2EGARDLESS OF WHETHER AMPLITUDE AND PHASE NULLING OR PHASE 
 Skolnik (ed.), McGraw­ Hill Book Co., New York, 1970.  10. Hill, J. 
 A. Oliner and G. H. 
 Given that the  beamwidth of the antenna is fixed, the integration time can be increased only if the  beam is pointed to maintain illumination of the desired target, much as a spotlight  from a moving vehicle dwells on an area of interest. The usual consequence of fine  resolution in SpotSAR mode is smaller range swath and an azimuth size that is limited  above by the width of the antenna’s footprint. The required steering rate is relatively  slow, typically a few degrees over a few seconds, implemented either by moving the  antenna beam or by yaw-steering the spacecraft. 
 TUDE FLUCTUATIONS THAT OCCUR DURING THE TIME THE BEAM IS MOVED FROM SIDE TO SIDE OR UP AND DOWN )T IS ALSO SUSCEPTIBLE TO FALSE  MODULATION ON SIGNALS  FROM COUNTERMEASURES  4HE ECHO FLUCTUATIONS NOT RELATED TO ANTENNA BEAM POSITION CAUSE FALSE TARGET ANGLE 
 BOARD  REAL 
 TABLE 1.2 JETDS Equipment Indicators* Installation (first letter) A Piloted aircraft B Underwater mobile, submarine D Pilotless carrier F Fixed ground G General ground use K Amphibious M Ground, mobile P Portable S Water T Ground, transportable U General utility V Ground, vehicular W Water surface and underwater combina- tion Z Piloted and pilotless airborne vehicle com- binationType of equipment (second letter) A Invisible light, heat radiation C Carrier D Radiac (radioactive detection, indication, and computation de- vices) E Laser G Telegraph or teletype I Interphone and public address J Electromechanical or inertial wire-covered K Telemetering L Countermeasures M Meteorological N Sound in air P Radar Q Sonar and underwater sound R Radio S Special types, mag- netic, etc., or combi- nations of types T Telephone (wire) V Visual and visible light W Armament (peculiar to armament, not other- wise covered) X Facsimile or television Y Data processingPurpose (third letter) A Auxiliary assembly B Bombing C Communications (re- ceiving and transmit- ting) D Direction finder recon- naissance and/or sur- veillance E Ejection and/or release G Fire control or search- light directing H Recording and/or re- producing (graphic meteorological) K Computing M Maintenance and/or test assemblies (in- cluding tools) N Navigational aids (in- cluding altimeters, beacons, compasses, racons, depth sound- ing, approach and landing) Q Special or combination of purposes R Receiving, passive de- tecting S Detecting and/or range and bearing, search T Transmitting W Automatic flight or remote control X Identification and rec- ognition Y Surveillance (search, detect, and multiple- target tracking) and control (both fire con- trol and air control) *From Military Standard Joint Electronics Type Designation System, MIL-STD-196D, Jan. 19, 1985. In the first column of Table 1.2, the installation letter M is used for equipment installed and operated from a vehicle whose sole function is to house and trans- port the equipment. 
 38 THERADAR EQUATION [SEC. 210 practically never depends onthedetection ofalone signal pulse, but on reception, from the same range and bearing, ofrepeated signal pulses. This has aprofound influence onthe statistical problem that wehave been discussing because, whereas thenoise fluctuations during successive sweeps 1are completely independent, the signal can bemade toappear atthesame position ineach sweep. 
 NAL COMPONENTSTARGET ECHOES  CLUTTER   AND EXTERNAL NOISEAFTER TAKING ACCOUNT OF  THE ARTIFACTS INTRODUCED BY QUANTIZATION AND TIMING JITTER  ESPECIALLY IN MULTI 
 15.19 the optimum average /SCR has been computed for several different values of the CPI as a function of the normalized spectrum width. These results may be used as a point of reference for practical doppler processor designs as discussed in Sec. 15.8. 
 With theupper and lower limits ofthe contour determined, the problem was now topush themaximum range outtothebest possible value. Adetection range of180 miles forafour-engine aircraft appeared to bethe best that could beexpected, and the contour thus determined is. SEC. 
 38. Fox, G. A., S. 
 Among the general class of effective-earth-radius models are the Standard  Propagation Model ( F-Factor),2 the Terrain Integrated Rough Earth Model (TIREM),8  the Irregular Terrain Model (ITM) also known as Longley-Rice,9 and the Spherical  Earth Knife Edge (SEKE).10 While these effective-earth-radius models are of the same nature, they do not  implement the various propagation mechanisms equally. For example, the F-factor  model properly implements multipath propagation for over-water surfaces whereas the  TIREM model is based upon knife edge diffraction techniques, making the TIREM  model inappropriate for over-water applications. Again, while troposcatter may be  unimportant for active radar applications, its effects need to be included for applica - tions of radar intercept by other sensors. 
 SYNCHRONOUS ORBIT AT  ^ KM ALTITUDE -ISSION OBJECTIVES INCLUDE  POLARIMETRIC DIVERSITY AND INTERFEROMETRY 4HE TWO BASELINE MULTI 
 Appl. Earth Obs. 2017 ,10, 2249–2273. 
 (ed.): Proc. Effect Ionosphere on Radiowave Syst., ONR/ AFGL-sponsored, pp. 262-272, Apr. 
 ORBIT 3!2 OPERATIONAL  LIMIT OF TEN MINUTES * 
 153-161, April, 1962.  41. Horton. 
 Radar Conf ., Toulouse, October 2004. 71. S. 
 .J. CHAPTER  TEN  DETECTION OF RADAR SIGNALS IN NOISE  The two basic operations performed by radar are (I) detectio~t of the presence of reflecting  objects, and (2) exrractiotl of information from the received waveform to obtain such target  data as position, velocity, and perhaps size. The operations of detection and extraction may be  performed separately and in either order, although a radar that is a good detection device is  usually a good radar for extracting information, and vice versa. 
 Predictions concerning the average performance of  random phenomena are possible by observing and classifying occurrences, but one cannot  predict exactly what will occur for any particular event. Phenomena of a random nature can he  described with the aid of probability theory.  Probability is a measure of the likelihood of occurrence of an event. 
 Capon, J.: Optimum Weighting Functions for the Detection of Sampled Signals in Noise, IEEE  Trans., vol. IT-10, pp. 152-159, April, 1964. 
 143-161, May, 1958; discussion, pp. 161--172.  58. 
 1022-1028, 1977. 50. Wilson, J., and H. 
 Spaulding and J. S. Washburn, “Atmospheric radio noise: Worldwide levels and other char - acteristics,” NTIA Rept. 
 To begin  with, the displacement of the Earth’s magnetic axis from its rotational axis means that  the ionosphere does not preserve a more or less constant form enveloping a rotating  earth. Near the magnetic equator, where the geomagnetic field is close to horizon - tal, atmospheric tides and associated winds drive the so-called E-region and F-region  ch20.indd   14 12/20/07   1:15:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 .............7oo Polarization. Horizontal Azimuth beamwidth. ..”. 
 ABLE  AND CAN HAVE LOWER ACQUISITION AND OPERATING COSTS /NE POSSIBLE DISADVANTAGE IS THAT SHEET 
 Solid curves are for the E plane ({J  measured in the plane of the E vector); dashed curves are for the H plane (fl measured in the plane of the 11  vector, perpendicular to the E vector).6u9 . OTHER RADAR TOPICS 559  frequency alone and the radar has no MTI capability. Also, the location of the target position  from the measurement of the total scattered ·path length S is indeterminate, as mentioned  previously. 
   %LECTROMAGNETIC  #OMPATIBILITY !NALYSIS #ENTER  !NNAPOLIS  -$  3EPTEMBER    ! ' ,ONGLEY AND 0 , 2ICE  h0REDICTIONS OF TROPOSPHERE RADIO TRANSMISSION LOSS OVER IRREGULAR  TERRAIN ! COMPUTER METHOD v %NVIRONMENTAL 3CIENCE 3ERVICES !DMINISTRATION 4ECH 2EP %2,  
  0) 0$#    WHERE 0/ IS THE 2& POWER OUTPUT   0) IS THE 2& POWER INPUT  AND  0$# IS THE TOTAL   DC POWER INPUT &IGURE  AND &IGURE  ILLUSTRATE THE ADVANTAGES OF 'A. AT  '(Z WHEN  COMPARED WITH THE PHYSICAL GEOMETRY OF AN IDENTICALLY SIZED 'A!S 0(%-4 TRANSISTOR   *#) ,#+ " -#') $'  $  0%% 
 1.2  1.2 Radar Equat ion  .......................................................  1.6  Tracking  ............................................................  1.8  Volume Search  .................................................. 
 This hardness level is adequate for SBR deployment in many of the candidate orbits with a mis- sion life in the natural environment of several years. A hardness of 5(1O)6 rads (Si) which may be achievable is required for a 5-year mission life. Survival in a saturated nuclear environment typical of a high-altitude nuclear burst requires a hardness of 1 to 5(1O)7 rads (Si), depending upon the specific orbit. 
 This also results in va rious “beat fre- quencies” for identical targets, a fact that can also be exploited.     Figure 13.18  Typical double -trapezoidal modulation for ACC sensors.   13.3.4.2  FSK Procedure   FSK modulation procedures are similar to the instrumentation Radar procedure from Radar  measuring technology. 
 PULSE STAGGERING AND DWELL 
 WhenusedintheFMaitimeter, thetechnique ofservo-controlling thefrequency excur­ sionisusuallyappliedatallaltitudes aboveapredetermined minimum. Sincethefrequency excursion t1fisinversely proportional torange,theradarisbetteroperated atverylow altitudes inthemorenormalmannerwithafixed4f,andhenceavarying beatfrequency. Measurement errors.Theabsolute accuracy ofradaraltimeters isusuallyofmoreimportance atlowaltitudes thanathighaltitudes. 
 ING TO THIS SEGMENT IS FOUND AS   03 FFF ALL 3 F   
 stored clutter map, raw video, outlines of areas of weather blanked by the operator,  display of stored llight plans, and time-compressed display of several successive radar scans.  Also it can aid in lhe requesting of height-finder data by the operator, blanking of areas  containing excessive interference or weather, providing training of operators by superimposing  simulated targets. and other functions necessary for an air-traffic-control system or air-defense  system. 
 122 INTRODUCTION TO RADAR SYSTEMS  where i = 1, 2, . , N represents the ith tap, and k is an index from O to N - I. Each value of k  corresponds to a different set of N weights, and to a different doppler-filter response. 
 FREQUENCY BANDSv 4HUS  THERE MAY BE $ 
 POLARIZATION FOR TELEMETRY  !FTER EACH POLE 
 6.29); one pattern isused forsearch and the other forhoming. Each pattern con- sists ofaleftand aright lobe. Inthesearch position these lobes extend broadside tothe airplane; inthe homing position they extend nearly straight ahead, sothat they overlap toaconsiderable extent. 
 BAND RADAR  THAT USES SIX SIMULTANEOUS BEAMS TO COVER A VOLUME OF ATMOSPHERE IN A MUCH  SHORTER VOLUME COVERAGE TIME THAN A MECHANICALLY SCANNED SINGLE BEAM RADAR 4HIS RAPID UPDATE SCAN IS IMPORTANT FOR MEASURING VIOLENT CONVECTIVE STORMS  ESPE 
 FED #ASSEGRAIN ANTENNAS 4HE BLOCKAGE  CAN BE MINIMIZED BY CHOOSING THE DIAMETER OF THE SUBREFLECTOR TO BE EQUAL TO THAT OF THE FEED  4HIS OCCURS WHEN  $F K3M L   WHERE K IS THE RATIO OF THE FEED 
 With reflector antennas. this results in a loss  of angle sensitivity and antenna gain.  5.5 TARGET-REFLECTION CHARACTERISTICS ANO ANGULAR  ACCURACY30·41 ·Q5  The angular accuracy of tracking radar will be influenced by such factors as the mechanical  properties of the radar antenna and pedestal, the method by which the angular position of the  antenna is measured, the quality of the s~a systeQ1, the stability of the electronic circuits, the  noise level of the receiver, the antenna beamwidth, atmospheric fluctuations, and the reflection  characteristics of the target. 
 A. Fabrizio, “Stochastic constraints in non stationary  hot clutter cancellation,” IEEE Int. Conf. 
 SURVEILLANCE RADARS )TS WAVELENGTH MIGHT BE ABOUT  CM ROUNDING OFF  FOR  SIMPLICITY  7ITH THE PROPER ANTENNA  SUCH A RADAR MIGHT DETECT AIRCRAFT OUT TO RANGESp  OF  TO  NMI  MORE OR LESS 4HE ECHO POWER RECEIVED BY A RADAR FROM A TARGET CAN VARY OVER A WIDE RANGE OF VALUES  BUT WE ARBITRARILY ASSUME A hTYPICALv ECHO SIGNAL FOR ILLUSTRATIVE PURPOSES MIGHT HAVE A POWER OF PERHAPS  
 74. Carter, P. S., Jr.: Mutual Impedance Effects in Large Beam Scanning Arrays, I RE Trans., vol. 
 S. Zrnic, “Simulation of weather-like doppler spectra and signals,” J. Appl. 
 ITY -ATERIALS THAT SIMULTANEOUSLY SUPPORT EXPOSURE TO SHOCK  VIBRATION  TEMPERATURE CYCLING  AND ADEQUATE THERMAL MANAGEMENT MUST BE USED -ATERIALS THAT MATCH VERY CLOSELY THE COEFFICIENT OF THERMAL EXPANSION #4%  OF THE SEMICONDUCTOR MATERIAL MUST BE USED IN THE DESIGN OF THE HOUSING SUCH THAT CRACKING OF THE SEMICONDUCTOR DEVICES DOES NOT OCCUR DURING THERMAL CYCLING THAT HAPPENS DURING NORMAL OPERATION OR DURING TEMPERATURE CHANGES DURING ASSEMBLY AND TEST %LECTRICAL )NTERCONNECTION #ONSIDERATIONS  4HE INTERCONNECTION OF --)# CHIPS  WITHIN THE 42 MODULE MUST UTILIZE CONTROLLED IMPEDANCE TRANSMISSION LINES WITH LOW INSERTION LOSS 4HUS  SOME COMBINATION OF HIGH 
 Record, vol. 8, pt. 4, pp. 
 Thunderstorm Prediction. Wilson and Schreiber74 illustrate how modern me- teorological doppler radar can be used to detect locations where new thunder- storm development is likely to occur. Modern radars have sufficient sensitivity to detect clear-air discontinuities in the lower 2 to 4 km of the atmosphere. 
 BOARD THE 4ROPICAL 2AINFALL -EASURING  -ISSION 42--  SATELLITE v )%%% 4RANS 'EOSCI 2EMOTE 3ENS  VOL   PP n    % )M ET AL  h3ECOND 
 RADAR RECEIVERS  6.456x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 provide the desired stopband rejection response. The kth order CIC filter for decima - tion factor D has transfer function:  H z zz zKm mDKDK ( )=  =− −  − =− − − ∑ 01 11 1 (6.49) A polyphase filter is a filter bank that splits an input signal into D sub-band filters  operating at a sample rate reduced by a factor D, providing a computationally efficient  approach to performing the FIR filtering followed by decimation in a digital receiver.  Rather than computing all the filter output samples and only using every Dth sample,  the polyphase approach calculates only those that are actually used. 
 An example is given in Willis.1 Even though one pulse must be chased at a time, a hitchhiker operating in the  co-site region has time to capture all pulses from a monostatic radar that uses range- unambiguous PRFs. Furthermore, when operating in the transmit- or receive-centered  ovals (refer to Table 23.2) a hitchhiker can operate with range-ambiguous PRFs, for  example, when transmitted from an airborne radar. Examples are given in Willis.1 ch23.indd   28 12/20/07   2:21:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 There  are radars that are fully adaptive, but they have only a limited number of elements  that can be economically handled in an adaptive array. Arrays with a large number of  receiving elements need some form of processing reduction. One method of partial  adaptivity is to arrange the array elements in subgroups that form the inputs of the  adaptive processor. 
 MENT IN WHICH THE TARGET  IS EMBEDDED EG  CLUTTER RETURNS  UNINTENTIONAL INTERFERENCE   UNCONTROLLABLE ENVIRONMENTAL REFRACTION  AND ABSORPTION   THE RANDOM NATURE OF THE INTERFERENCE  AND THE RADAR ITSELF SYSTEM NOISE TEMPERATURE  SIGNAL DISTORTIONS  ETC  .EVERTHELESS  RADAR RANGE PREDICTION MADE UNDER AVERAGE CONDITIONS PROVIDES A PRE 
 If precise frequency control is needed, better than can be achieved through the magnetron tuner after allowing for backlash, warmup drift, pushing, pulling, etc. 2. If precise frequency jumping is required, or frequency jumping within a pulse or within a pulse group. 
 The normalantenna patternisdepicted inFig.7.26aasasquarebeamextending from0=°to (J=00,Thecosecant-squared patlerninFig.7.26bisshownasauniform beamoverthe range0:s;(/:s;(Joanddecreases ascsc20(csc200overtherange00<0:s;Om'ThegainGofthe squarebeaminFig.7.26adivided bythegainGcofthecosecant-squared antenna beamin Fig.7.26h i~ Forsmallvaluesof00, GG:::::::2 -00cotOm c(7.29). 260 INTHODUCTION TO KADAH SYSTEMS  ., .  Figure 7.25 Cosecant-squared antenna of the ANlTPN-19 landing system. 
 LITE  LAUNCHED IN  4HE OPERATIONAL RELIABILITY OF PASSIVE 
 13.14:  GA( ) cos q q0 2 04=π λ  If it is assumed that each of the N elements in the array shares the gain equally, the  gain of a single element is from Eq. 13.16:  GA Ne( ) cos q q =4 2 0π λ  If the element is mismatched, having a reflection coefficient Γ(q, f ) that varies as  a function of scan angle, the element gain pattern is reduced to  GA Ne( ) (cos)[| ( , )| ] q q = −4122 π λθ φΓ   The element pattern is seen to contain information pertaining to the element  impedance.50–53 The difference between the total power radiated in the element pat - tern and the power delivered to the antenna terminals must equal the reflected power.  In terms of the radiation pattern of the scanning array, this means that since the  scanned antenna patterns trace out the element pattern, it follows that the average  power lost from the scanned pattern is equal to the power lost from the element  ch13.indd   22 12/17/07   2:39:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 2.96  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 The radar system must have features to cope with these situations. For example, if pulse- to-pulse staggering is used, the ambiguous-range clutter will not cancel and either the  PRI must be increased or the PRI must be made constant over the azimuth angles from  which the ambiguous range clutter is received. And be forewarned of a pitfall into which  many radar designers have fallen. 
 Barrick and Q. Peake, “A review of scattering from surfaces with different roughness scales,”  Radio Sci ., vol. 3, pp. 
 The ARSR-3 is really two separate radars, each at a different frequency, operating into a  single antenna. Either system can be used separately (simplex operation) or both can be used  simultaneously (diplex operation). The chief reason for the dual channels in this radar is to  provide greater availability of the radar. 
 1–20, 1974. ch15.indd   42 12/15/07   6:17:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 KM RESOLUTION CELLS  POSTED ON A  
 also a consequence of tlle broad fan beams. The effect  of~iiultip;rtli is sirtiil;lr to the elfect of glint discussed in Sec. 5.5 for trackitig radars. 
 ING OF ELECTROMAGNETIC WAVES RESPONSIBLE FOR SEA CLUTTER 4HE BASIC OCEANOGRAPHIC  DESCRIPTOR OF THE SEA SURFACE  HOWEVER  IS THE  WAVE SPECTRUM  WHICH SAYS LITTLE ABOUT  THE DETAILS OF THESE FEATURES  BUT CONTAINS A GREAT DEAL OF INFORMATION ABOUT THE SEA  SURFACE IN GENERAL AND IS CENTRAL TO THE APPLICATION OF THE "RA GG SCATTERING HYPOTHESIS  !CCORDINGLY  SOME TUTORIAL MATERIAL DESCRIBING THE SPECTRAL CHARACTERIZATION OF THE SEA SURFACE IS INCLUDED IN THIS SECTION  ALONG WITH A BRIEF DISCUSSION OF SURFACE EVENTS SUCH AS WAVE BREAKING AND OTHER SURFACE EFFECTS THOUGHT TO CONTRIBUTE TO THE PRODUCTION OF SEA SPIKES 4HERE ARE BASICALLY TWO TYPES OF SURFACE WAVES   CAPILLARY AND  GRAVITY  DEPENDING  ON WHETHER SURFACE TENSION OR GRAVITY IS THE DOMINANT RESTORING FORCE 4HE TRANSITION BETWEEN ONE AND THE OTHER TAKES PLACE AT A WAVELENGTH OF ABOUT  CM  SO THE SMALLER CAPILLARY WAVES SUPPLY THE SURFACE FINE STRUCTURE WHILE GRAVITY WAVES MAKE UP THE LARGER AND MOST VISIBLE SURFACE STRUCTURES 3EA WAVES HAVE THEIR ORIGIN PRIMARILY IN THE WIND  BUT THIS DOES NOT MEAN THAT THE hLOCALv WIND IS A PARTICULARLY GOOD INDICATOR OF WHAT THE WAVE STRUCTURE BENEATH IT WILL BE )N ORDER TO AROUSE THE SURFACE TO ITS  FULLY  DEVELOPED OR  EQUILIBRIUM STATE  THE WIND MUST BLOW FOR A SUFFICIENT TIME  DURATION   OVER A SUFFICIENT DISTANCE    FETCH  4HAT PART OF THE WAVE STRUCTURE DIRECTLY PRODUCED  BY THESE WINDS IS CALLED  SEA "UT WAVES PROPAGATE  SO EVEN IN THE ABSENCE OF LOCAL  WIND  THERE CAN BE SIGNIFICANT LOCAL WAVE MOTION DUE TO WAVES ARRIVING FROM FAR AWAY  PERHAPS FROM A DISTANT STORM 7AVES OF THIS TYPE ARE CALLED  SWELL  AND SINCE THE SURFACE  OVER WHICH THE WAVES TRAVEL ACTS AS A LOW 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 false sense of security. 
 Orbital altitudes were 240 km and 220 km, respectively, so that radar range and incidence angles were different. GEOS-C SBR System Characteristics.8'19^21 The GEOS-C radar altimeter was a precision Ku-band (13.9-GHz) SBR altimeter developed primarily to measure ocean surface topography and sea state. It was a complex multimode radar system with two distinct radar gathering modes (global and intensive modes) and two corresponding self-test-calibration modes for use in on-orbit functional test and instrument calibration. 
 Any use is subject to the Terms of Use as given at the website. Radar Receivers. 6.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 Characteristics of Amplifiers and Mixers.  Noise figure, amplifier gain, mixer  conversion loss, 1 dB compression point, and third order intercept point are the most  common performance parameters specified for amplifiers and mixers. 
 The second statement which can bemade concerns the probability that atsome arbitrarily selected instant theoutput power will befound toliebetween some specified level, P,and P+dP.This probability, which weshall label WI(P)dP,isgiven by W,(P)dP=#oe-$dP. (22) POistheaverage power, determined over along time. Astatement which iseasily seen tobeequivalent tothis is:The prob- ability that the power exceeds some specified level P,atanarbitrarily P selected instant, isjust e‘F”. 
 STATE DEVICES EXHIBIT IMPROVED MEANTIME BETWEEN  FAILURES -4"&  IN COMPARISON WITH TUBE 
 Proceedings International Radar Conference  IEEE Radar 05, pp. 435  – 440, Arlington, VA, USA, May 2005   15.3 Synthetic Aperture Radar   − J. Kim, M. 
 MAP MODE IS MULTI 
 IGARSS95 , vol. 2, pp. 859–861, 1995. 
 57, pp. 171-178, February,  1969.  67. 
  
 OF 
 In Figure 4, the predicted energy ratio is deﬁned as the energy amount of the predicted signal to the energy amount of the range proﬁle.  3UHGLFWLRQIDFWRU3UHGLFWHGHQHUJ\UDWLR Figure 4. Predicted energy ratio curve with the prediction factor. 
 vol. 51.  pp. 
 TERING HYPOTHESIS    AND THE AGREEMENT OFTEN LOOKS GOOD  ESPECIALLY FOR VERTICAL  POLARIZATION AT THE HIGHER WIND SPEEDS 9ET WHY THIS IS SO REMAINS A PUZZLING CURIOSITY )N THIS EXAMPLE  THE WIND SPEEDS ARE HIGH SO THE SEA WILL BE ROUGH  BUT IT WAS NOTED ABOVE THAT THE 30- APPROXIMATION USED IN &IGURE  REQUIRES WAVEHEIGHTS MUCH LESS THAN A CENTIMETER  SO THIS APPROXIMATION IS TOTALLY INVALID FOR THESE DATA -OREOVER  THE 0HILLIPS SPECTRUM WAS USED AS THE SEA SURFACE SPECTRUM  BUT THERE IS NO EVIDENCE THAT THIS SPECTRUM HOLDS DOWN TO THE REQUIRED CAPILLARY WAVELENGTH OF ABOUT  CM )N FACT  THE NATURE OF THE SEA SPECTRUM IN THIS RANGE REMAINS UNCERTAIN AND HAS BEEN REFERRED TO AS hONE OF THE MOST EXCITING UNSOLVED PROBLEMS OF THE SEA SURFACEv  4HE  PRIMARY EFFECT OF THE  TWO 
 The video  signals shown in Fig. 4.2 are called bipolar, since they contain both positive and negative  arnplit udes.  Movirig targets may be distinguished from stationary targets by observing the video  output on an A-scope (amplitude vs. 
 The noise introduced by a network may also be expressed as an eflective  ~roise tenlperattrre, T,, defined as that (fictional) temperature at the input of the network which  would account for the noise AN at the output. Therefore AN = kT, B, G and  Te = (F, - l)To (9.7)  The system noise tenlperature T, is defined as the effective noise temperature of the receiver  system including the effects of antenna temperature T,. (It is also sometimes called the system  Figure 9.1 Two networks in cascade. 
 For this reason the first grid is also known as the sltodo,c!  q~.rd 'I'tic pilrposc of the shadow grid is to suppress electron emission from those portions of  tlie catl~ode wliicli otlicrwise would be intercepted by the second, or control, grid. The cathode  surface utider- each opening of the first grid is dimpled. Each ditnple is aligned with the  openings of tlie grid so tliat bearnlets are formed within each grid opening. 
 This is called .f/11.x drirc. It has the further advantage of having reduced  temperature sensith'ily. Instead of using a number of individual toroids of different lengths in  cascade. 
 ELOBE ANTENNA  IT IS IN THE IMPORTANT CASE OF CLOSE TO MAIN 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 14.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 the offensive PO diffraction coefficients from the time-honored wide-angle wedge  solution. 
 RELATED ROLE OF HIGH FREQUENCY  (&  OVER 
 T.: Random Errors in Aperture Distributions, IRE Trans., vol. AP-7, pp. 369-372,  Octoher. 
 13.20 and 13.21). 4.3. Pulse Radar and C-w Radar.—The last section has abearing on the relative capabilities ofpulse radar and so-called “c-w radar,” by which ismeant asystem operating atrelatively low peak power, with avery narrow receiver pass band, and making use ofthe doppler prin- ciple, oroffrequency modulation. 
 (a) Flopover; (b) scale-o f-two. Inthescale-of-two, pulses from asingle source areapplied toboth sides; whenever apulse arrives thecircuit changes from one stable state totheother. Thus two pulses are required tocomplete afull cycle. 
 The extra expenditure ofpower involved isusually not justifiable forthis rather inflexible method, especially since the pulse methods areextremely simple. Asasecond method, themodulator pulses themselves can beused to represent the increments ofscanner angle 1ifthe scanner motion can be made sufficiently constant tocontrol the modulator triggering satis- factorily. Such asystem isrepresented inFig. 
 ................................ ................................ ................................ 
 Approximately one  gallon of water per minute with a pressure drop of 9 psi is required. The tube is housed in a  magnetically shielded package that stands approximately 2 ft high with a diameter of 1 ft and  weiglis 210 Ih. A Vac-Ion vacuum purnp is included within tlie magnetically shielded package  to inonitor the vacuum and to provide continuous pumping action during operation. 
 25.4 DSP TOOLS This section will describe various processing architectures and techniques that are  available to DSP engineers. Phase Shift.  The phase shift is a core element in DSP design, and there are sev - eral techniques available to implement one. 
 R. E. Clapp, “A theoretical and experimental study of radar ground return,” MIT Radiat. 
 BEAM AND SIDELOBE CLUTTER CANCELLATION 0ERFORMANCE #OMPARISONS  'IVEN THE NUMBER OF 34!0 ARCHITECTURES AND COR 
 It is interesting to note that although Hertz's experiments  were perrormed with relatively short wavelength radiation (66 cm), later work in radio engin­ eering was almost entirely at longer wavelengths. The shorter wavelengths were not actively  used to any great extent until the late thirties.  In 1903 a German engineer by the name of Hlilsmeyer experimented with the detection of  radio waves reflected from ships. 
 Thus at20kvand 48amp, thepower output is470 kw. This same power can also beobtained at25kvand 30amp with amagnetic field alittle less than 2700 gauss. Inaddition, itiscustomary toadd curves ofconstant efficiency obtained directly from theabove data. 
 BAND 3!2  SATELLITES 4HE #/3-/ 3!2S HAVE MULTIPOLARIZATION ACTIVE PHASED 
 Inmercury this attenuation isabout 0.11 db/in. at10hlc/sec. The attenuation due towall effects isless clearly understood but isbelieved tovary inversely. 
 It can usually be neglected at angles greater than 3 to 5' in most radar applications.  Although more refined models of atmospheric refraction must be considered where  precise radar measurements are important, the simplicity of the usual 4 earth approximation  makes it attractive for rough predictions.  The above discussion of refraction has been directed primarily to the aircraft target  located within the lower portion of the atmosphere called the troposphere. 
  ARRAY MAY BE TAKEN AS  TYPICAL OF AN ELEMENT IN A LARGE ARRAY &OR DIPOLES WITH NO GROUND PLANE THE COUPLING  BETWEEN ELEMENTS DOES NOT DECAY SO RAPIDLY  AND A  
 CAL PERFORMANCE IS POTENTIALLY MUCH HIGHER !DEQUATE CANCELLATION OF THE DIRECTIONAL INTERFERENCE IS OBTAINED IF THE RECEIVING CHANNELS ARE PROPERLY MATCHED IN AMPLITUDE AND PHASE ACROSS THE RADAR RECEIVING BANDWIDTH 4HIS CONDITION  IS NECESSARY TO ATTRI 
 position and velocity, assumitlg small velocity changes between observations, or data samples.  Benedict7' suggests that to minimize the output noise variance at steady state and the tran-  sient response to a maneuvering target as modeled by a ramp function, the a-B coefficients are  related by P = a2/(2 - a). Tlie particular choice of a within the range of zero to one depends  upon the system application, in particular the tracking bandwidth. 
 It is indeed, hut the relation between the wind and the sea conditions is  complex: hence. so will be the relation between the ·wind and the radar backscatter. The  capillary waves and the short gravity waves build up quickly with the wind so that· the value  of a0 measured with radars at the higher microwave rrequencies should be quite responsive to  wind conditions. 
 This is the value shown at  the upper left of the chart (6 dB). If the two  are out of phase, they cancel each other, and  there is no signal at all (off the lower left of  FIGURE 14.20  The far-field distance ( Reprinted with permission of  SciTech Publishing, Inc .50) FIGURE 14.21  Measurement error as a func - tion of the relative background power level ch14.indd   28 12/17/07   2:47:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Note that optical ﬂow is calculated based on the original reference and mission images. After obtaining the ﬂow vectors, the direction of the majority of ﬂow vectors is determined. The ﬂow vectors that are in this direction are applied to the two ﬁrst stage change maps to ﬁnd matches. 
 These, together with thetransformer efficiency, determine the amount ofaverage power which must bedksipated bythetransformer. Apulse transformer contributes acertain amount ofundesirable inductance and capacity tothepulser circuit. Special damping devices may benecessary toremove unwanted oscillations. 
 This would have been equivalent to an increase in noise-limited detection ranges by factors of 1.8 and 1.6times, respectively. Relative clutter-limited performance would have been deter- mined from the relative signal-to-clutter ratios, derived from ( 7.3). For these radars, the main variables would have been the azimuth beamwidth, θ°az, and the clutter reﬂectivity, σ0. 
 WIND TRACE CORRESPONDS TO A 2AYLEIGH DISTRIBUTION THE OTHER SEGMENTED TRACES ARE TWO 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo.  GROUND ECHO  16.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 The spectrum of fading can be calculated by a slight rearrangement of the radar  equation (Eq. 
 l •• '  Mechanical beam-scanning with planar twist-reflector. The antenna configuration shown in  Fig. 7.13 may be employed to·rapidly scan a beam over a relatively wide angle by mechanical  motion of the plarnir mirror. 
 ING UNIQUE SYNOPTIC DATA THAT HAVE REVOLUTIONIZED OUR KNOWLEDGE AND UNDERSTANDING OF BOTH GLOBAL AND LOCAL PHENOMENA   FROM %L .I¶O TO BATHYMETRY 3"2 ALTIMETER DATA  ALSO PROVIDE MEASUREMENTS OF SIGNIFICANT WAVE HEIGHT AND WIND SPEED !LTHOUGH ONE MIGHT CONSIDER ALTIMETERS TO BE RELATIVELY SIMPLE ONE 
 10.4 inthe selection ofproper operating conditions foramagnetron. The input voltage, input current, and magnetic field arechosen bymaking a compromise among such factors aspeak power output, efficiency, allow- able magnet weight, input impedance, and stability ofoperation. All thenecessary information canbeobtained from agood performance chart. 
 Themaximum phasechangerequired ofeachphaseshifterintheparallel-fed arrayis manytimes2rrradians. Sincephaseshiftisperiodic withperiod2rr,itispossible inmany applications touseaphaseshifterwithamaximum of2rrradians. However, ifthepulsewidth isshortcompared withtheantenna response time(ifthesignalbandwidth islargecompared withtheantenna bandwidth). 
 (/2):/. 2!$!2   Óä° FROM n KM 4HE CROSS 
 Deployable Antenna Flight Experiment—Preliminary Definition Study, Harris Corpo- ration, Third Q. Rev., June 24, 1981. 48. 
 Dashed curve gives onsd of grating  lobe ford 0.5A0; dot-dash curve for d = 0.6.t0.  travel down the transmission line. The finite time implies a finite bandwidth. 
 The mutual coupling between two small isolated dipoles68 should decrease as \lr in the H plane and 1/r2 in the E plane (E and H planes are interchanged for slots). Coupling measurements69 have shown that in the array environment the rate of decay is slightly greater than predicted above, indicating that some of the energy is delivered to other elements in the array and may be dissipated and reradiated from these elements. The same measurements have shown that the phase difference of the energy coupled to elements is directly proportional to their distance from the excited elements, indicative of a surface wave traveling along the array, leaking energy to each of the elements. 
 2 direct sampling, 25.38 Digital RF memory (DREM), 24.6 to 24.7 Digital signal processing hardware implementation, 25.35 to 25.37 timing dependence, 25.34 to 25.35 tools, 25.22 to 25.34 Digital upconverter (DUC), 25.21 to 25.22 Diode phase shifter, 13.51 to 13.52 Dipole antenna, 21.25 to 21.26 Direct digital downconversion, 25.10 to 25.15 Direct digital synthesizer (DDS), 6.22, 6.48 to 6.49, 25.20 to 25.21 Direct sampling digital receiver. 25.38 Direction finding (DF) and radar, 7.50 to 7.54 Directive gain, of an antenna, 12.5 Discrete Fourier transform (DFT), 25.32 to 25.34 Di splaced Phase Center Antenna (DPCA), 3.10 to 3.13, 3.19 to 3.21, 5.2 to 5.3 Distortion, in receiver, 6. 6 to 6.7 Doppler ambiguity resolution, 4.33 to 4.34. 
 If OB and (bB are the beamwidths in the two orthogonal planes, the beam area  B is approximately equal to BB 4B. Substituting into Eq. (7.3) gives  Ariotller expression for the gain sometimes used is  This was derived assuming a gaussian beamshape and with O,, (6, defined as the half-power  beamwidths.I3'  Power gain The definition of directive gain is based primarily on the shape of the radiation  pattern. 
 £Ç°Óä  2!$!2 (!.$"//+  COMPLEX NUMBERS THAT EACH RESULTS FROM ONE OF THE SCATTERERS 4HUS  WHEN TERRAIN   ESPECIALLY VEGETATION  IS IMAGED  THE AMPLITUDE VOLTAGE  OF A PARTICULAR PIXEL IS THE MAGNITUDE OF THE COMPLEX SUM OF THE COHERENT RETURNS FROM MANY SCATTERERS WITHIN THE PIXEL )N ANOTHER NEARBY PIXEL  EVEN IF THE TERRAIN IS NOMINALLY THE SAME AS IN THE FIRST PIXEL  THE COHERENT RETURNS WILL ADD DIFFERENTLY AND THE PIXEL MAGNITUDE WILL BE SOMEWHAT DIFFERENT 4HIS PHENOMENON  CHARACTERISTIC OF COHERENT IMAGERY  CAUSES 3!2 IMAGERY OF TERRAIN TO EXHIBIT MORE PIXEL 
 ENCE WILL CAUSE ONLY A FEW FALSE ALARMS ! COMPARISON OF THE RATIO DETECTOR WITH OTHER COMMONLY USED DETECTORS IS SHOWN IN &IGURES  AND  FOR NONFLUCTUATING AND FLUCTUATING TARGETS ! TYPICAL PERFORMANCE IN SIDELOBE JAMMING WHEN THE JAMMING LEVEL VARIES BY  D" PER PULSE IS SHOWN IN &IGURE  "Y EMPLOYING A SECOND TEST TO  &)'52%   )MPLEMENTATION OF A BINARY INTEGRATOR 4HE LETTER  # INDICATES A COMPARISON  FROM ' 6 4RUNK . Ç°£{  2!$!2 (!.$"//+  IDENTIFY THE PRESENCE OF NARROW 
 Aspect entropy extraction methods at the pixel and target level are respectively proposed using single-polarization CSAR data. The Gotcha public release dataset is used to illustrate our aspect entropy extraction methods. The results show that the aspect entropy of the pixel and the target can be successfully extracted by our methods. 
 CW AND FREQUENCY-MODULATED RADAR 99  27. Klass. P. 
 To illustrate a few of the experiments and their results: Kwoh and Lake11 measured  X-band returns from gentle breaking waves in a wave tank and found that specular  and curvature scattering appeared to dominate over Bragg scattering for such sur - faces. Keller et al.,122 measured X-band returns and surface spectrum simultaneously  in a wave tank and found Bragg-based theories might have credence at intermediate  grazing angles and strong winds, but were unable to account for scattering behavior  under other conditions.  Sletten and West113,114 made a two-pronged approach to break - ing wave scatter, constructing a metallic model of a breaking wave, comparing its  ch15.indd   36 12/15/07   6:17:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 A thorough  treatment of DFT weighting functions and their effects is given by Harris.11 ch25.indd   32 12/20/07   1:40:41 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 
   DATA  FOR EXAMPLE. £n°ÓÓ  2!$!2 (!.$"//+  3TANDARD IMAGE PRODUCTS USUALLY ARE hMULTI 
 Mattingly. R. L.: Radar Antennas, chap. 
 77. D. J. 
 GAIN PARADOX FOR A PHASED 
 Since most search radars are ambiguous in doppler, the use of different   FIGURE  2.7 Block diagram of MTD II signal processor ch02.indd   7 12/20/07   1:42:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 DIRECT THE TRANSMITTERS SIGNAL BACK TO THE TRANSMITTER AND THUS ITS MONOSTATIC RECEIVER   THE SPATIALLY SEPARATED HITCH 
 Figure 2.21. Vixen attenuator for ASV MK. II, with control set for minimum attenuation [ 15]. 
 Alogarithmic characteristic provides aconstant falsealarm rate(CFAR) whentheinputclutterornoisehasaRayleigh pdf.Theperformance ofthelog­ arithmic receiver innon-Rayleigh clutterisalmostasgoodasthem-out-of-II detector andis probably easiertoimpkment.14.28 Acomparison oftheperformance ofthevariousreceivers foraspecificcaseisshownin Fig.13.7. Log-FTC andlog-logreceivers. Thetechniques discllssed thusfarattempt toimprove the detection oftargetsinclutterbyincreasing thetarget-to-c1utter ratio.Therearealsosevaal techniques foundinradarsforthedetection oftargetsinclutterwhosepurpose istoprevent theclutterfromsaturating thedisplayorthereceiver, ortomaintain aconstant false-alarm rate(CFAR).Theyhavenosubclutter visibility inthattheyoffernoabilitytoseetargets masked byclutter,buttheydopermittargetslargecompared tothecluttertobedetected that mightotherwise belostbecause ofthelimiteddynamic rangeofthereceiving system. 
 It should be noted that microwave-feedthrough cancellation is of principal value in preventing saturation and in minimizing the effects of AM noise. Be- cause of the correlation effect, FM noise produced by spillover tends to cancel in the receiver. Near-in AM and FM noise produced by clutter is also beneficially reduced by the spillover servo, since, in nulling out the carrier, it automatically removes both sidebands, whatever their origin, as long as the decorrelation in- terval is short. 
 15.16 Approximate MTI improvement factor limitation due to pulse-to-pulse repetition-period staggering and scanning (all canceler figurations). 7(dB) = 20 log [2.5n/ Oy- 1)]; y = maximum period/minimum period. spectral width, and fd is the average doppler shift of the clutter. 
 SPEED DATA WERE COLLECTED AT DIFFERENT TIMES IN DIFFERENT PLACES UNDER DIFFERENT CONDITIONS OF SEA 
 Metal space-frame radomes can  be of large size, 150-ft diameter being quite practical. Designs up to 500-ft diameter have been  considered. The cross section of metallic members can be smaller than that of dielectric  members of equivalent strength; hence, t~e effect of aperture blocking is less. 
 The value of }'o for a "typical" twin-jet aircraft in level flight at near head-on or near tail-on  aspect is said38 to be equal to half the separation of the jet engines. For a ship at broadside, ,o  is approximately 0.15 times the ship length.  When angle errors due to glint are large, the received signals are small; that is, the  received signal amplitude and the glint error are negatively correlated. 
 GENERATED  WAVES WITH APPLICATION TO SCATTEROMETRY v * 'EOPHYS 2ES  VOL #   PP n    3 ! +ITAIGORODSKII  h/N THE THEORY OF THE EQUILIBRIUM RANGE IN THE SPECTRUM OF WIND 
 SQUARED DISTRIBUTION  +MX D   AND ITS INVERSE  +M 
 (6), (26). SEC.1610] CHOICE OF SYSTEM CONSTANTS 652 Asispointed out atthe end ofSec. 16.6, the dependence onxisonly approximate. 
 LIMITED FOOTPRINTS ARE APPROXIMATELY  KM BY  KM &OLLOWING ONBOARD PROCESSING  THE AVERAGE DATA RATE IS  KBITSS 3EA7INDS PERFOR 
 R. Ward: Detection Performance of the Cell Averaging LOGIdFAR Receiver,  IEEE Trans., vol. AES-8, pp. 
 It is appropriate, therefore, to examine the efficiency of nonmatched filters compared  with the ideal matched filter. The measure of efficiency is taken as the peak signal-to-noise  ratio from the nonmatched filter divided by the peak signal-to-noise ratio (2E/No) from the  matched filter. Figure 10.2 plots the efficiency for a single-tuned (RLC) resonant filter and a  rectangular-shaped filter of half-power bandwidth B, when the input is a rectangular pulse of  width t. 
 801-804, November 1978. 113. Ewell, G. 
 detector  net. \ sin 2rfS t  I  LIGIUIIVII UII,,IG  error detector h 3( 1 l Elevation l I I CI,,,~~;~,-,,~~, l Error  signal  servo '"  error detector  Figure 5.3 Block diagram of conical-scan tracking radar.  The receiver is a conventional superheterodyne except for features peculiar to the conical-  scan tracking radar. 
 ALLY EFFECTIVE PRODUCT. 
 INDUCED JITTER  SO THIS FACTOR MUST BE CAREFULLY MEASURED 3PECTRAL %MISSIONS  7HEN A RECTANGULAR 2& DRIVE PULSE IS APPLIED TO A SINGLE  MODULE  THE AMPLIFIER WILL TYPICALLY SHOW RISE AND FALL TIMES THAT ARE ON THE ORDER OF NANOSECONDS 4HE OUTPUT SIGNAL SPECTRUM OF THIS PULSE SHAPE  MAY NOT MEET SPEC 
  
 It is the chapter authors who make any handbook a success. My sincere thanks to them all. As stated in the Preface of the previous edition, readers who wish to reference or quote material from the Radar Handbook  are asked to mention the names of the individual chapter authors who produced the material. 
 T. Sandwell, “Conventional bathymetry, bathymetry from space, and   geodetic altimetry,” Oceanography , vol. 17, pp. 
 STATE POWER AMPLIFIERS 0EAK TRANSMITTED POWERS ARE  7 AND  7 -ASS AND INPUT POWER OF THE TWO RADARS ARE  KG AND  KG AND  7 AND  7 4HE ONLY OTHER INSTRUMENT IN THE PAYLOAD IS A MICROWAVE RADIOMETER 4O PROVIDE COVERAGE AT MORE LATITUDES  THE SPACECRAFT HAS A HIGHER INCLINATION ORBIT THAN 42--S  n 4HE MAIN ADVANTAGES OF THE SECOND FRE 
 3, 1946. zThe design problems involved inthisandother MTI receiver circuits aredis- cuaaed inVol. 23,Chap. 
 Because  this layer is unstable, the resultant convective processes tend to concentrate any avail - able moisture near the top of the layer. This in turn creates a positive N gradient or  subrefractive stratum aloft. This layer may retain its subrefractive nature into the early  evening hours, especially if a radiation inversion develops, trapping the water vapor  between two stable layers. 
 T. Ulaby, R. K. 
 8.18, when one has an interfering target, the P0 does not approach 1 as SIN increases. Another approach26 which censors samples in the reference cell if they exceed a threshold is briefly dis- cussed in the subsection "Nonparametric Detectors." Finn28 investigated the problem of the reference cells spanning two continuous different "noise" fields (e.g., thermal noise, sea clutter, land clutter, etc.). On the basis of the samples, he estimated the statistical parameters of the two noise fields and the separation point between them. 
 14.5) is a form of adaptive antenna that uses a small  rlurnber of auxiliary elerrients to adaptively place nulls in the direction of external noise  sources. It is art exaniple of a successful application of the principles of the adaptive antenna  that utilizes only a relatively few number of adaptive elements. The fully adaptive array of  large size is, in theory, capable of nulling a larger region of space than a system with but a  relatively few adaptive elements, as in the sidelobe canceler. 
 TION ON ALL  CHANNELS IS PROVIDED THROUGH CIRCULATORS 4HE  CHANNELS ARE PROCESSED SEPARATELY THROUGH  RECEIVERS  FINALLY FEEDING THE 34!0 SUBSYSTEM WITH  
 Having undertaken research into the design of airborne maritime reconnaissance radar systems during my professional career I wished to understand the technical history of these systems. There are many excellent memoires of the people involvedin early development of these radars during WWII, but little technical detail on the design, operation and performance of these systems has been published. Radar ﬁrst entered front-line service for maritime reconnaissance at the start of WWII, toprovide long-range monitoring of surface ships and, most importantly, as a key component in the battle against the growing German U-boat threat. 
 o£  PK3 M KK M"FF SCAT INC     ¯¯      PKM M 3 M 3M M'      FF F FJJ J J   M MG MG DD   o£ 
 Itturns outinfact that forthepoint target with uindependent ofangle, thequantity hR~,.isconstant, rather than hR5.,,and Sisproportional toazrather than toah.. SEC. 26] TIIEBEA6’ON EQUATION 27 Inpractice itisnotfeasible toproduce apattern which exactly meets the specification ofEq. 
 42. Chadwick, R. B .. 
 The tabulated monopulse ratio is inverted in the lookup process by entering the table with the measured monopulse ratio and find- ing the corresponding off-boresight angle. The full-vector monopulse processing in Fig. 20.5/7 differs somewhat from that in Fig. 
 883 - 884. May. 1968. 
 GUIDED MISSILES -ULTIPLE  DECOYS ARE SOMETIMES DISPENSED AT PREDETER 
 ISSUE  v (UGHES !IRCRAFT )$#  /CTOBER       UNCLASSIFIED REPORT  * +IRK  h4ARGET $ETECTION 3YSTEM IN A -EDIUM 02& 0ULSE $OPPLER 3EARCH4RACK 2ADAR  2ECEIVER v 53 0ATENT     + 'ERLACH  h3ECOND TIME AROUND RADAR RETURN SUPPRESSION USING 02) MODULATION v  )%%%  4RANSACTIONS  ON  !EROSPACE  AND  %LECTRONIC  3YSTEMS   VOL !%3 
 Moreira, A.; Prats-Iraola, P .; Younis, M.; Krieger, G.; Hajnsek, I.; Papathanassiou, K.P . A tutorial on synthetic aperture radar. IEEE Geosci. 
 AVERAGED CHARACTERISTIC 4HIS IS A REFERENCE POINT ABOUT WHICH THERE WILL BE CONSIDERABLE VARIATION FOR A TYPICAL TIME PERIOD OF INTEREST &OR EXAMPLE  WITH ONLY  MINUTE OF DATA THE NOISE POWER  R ANG WOULD  VARY OVER  TO  TIMES THE LONG 
 image. The tracking has been described as "wild" and can be great enough to cause the radar  to break track. The effect is most pronounced over a smooth water surface where the reflected  s~gnal is strong. 
 and equipment generally costly and unreliable. There is  reason to believe, however, that this is not fundamental and that equipment shortcomings  eventually can be overcome with sufficient effort. There exists adequate technology to either  side of the millimeter wave spectrum: at the longer wavelengths (microwaves) and at the  shorter wavelengths (IR and visual). 
 llowcvcr, they  tend to exhibit a slow but predictable deterioration with respect to internal leakage as a result  of mechanical wear.  Both electric and hydraulic drives are used in surveillance radars. Surveillance antennas  operate at constant rotation rate. 
 A shipborne radar is likely to be receiving messages from many items of naviga - tion equipment, such as AIS, GPS, gyrocompass, log, and echo sounder, and is also  likely to be communicating track information to electronic chart systems and possibly  other radar displays. A number of manufacturers produce radars specifically designed to be used on  vessels using the world’s major inland waterways. These are known as river radars . 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°£Î 3CAN3!2 COVERAGE  
 F. Smith, R. N. 
 8077-4-T, May 1967.  9. L. 
 Many authors have investigated various detectors, comparing detection per - formance and angular estimation results with optimal values, and many of these results  are presented later in this section. In the original work on detectors, the environment was assumed known and homo - geneous, so that fixed thresholds could be used. However, a realistic radar environ - ment (e.g., containing land, sea, and rain) will cause an exorbitant number of false  alarms for a fixed-threshold system that does not utilize excellent coherent processing. 
 3.10 EFFECT OF MULTIPLE SPECTRA An airborne search-radar system may be operated at an altitude so that the radar hori - zon is approximately at the maximum range of interest. This results in sea or ground  clutter being present at all ranges of interest. Other clutter sources such as rain and  chaff may coexist with the surface clutter. 
 A TYPICAL THREE-VALVE TIME~BASE  GENERATING CIRCUIT  ‘Hard’ (highly evacuated) valves are used throughout.  The circuit of the hard-valve time-base is shown in  Fig. 1. 
 This also means that the multipliers would have  to handle the larger number of bits on the inputs. This method could get unwieldy for  large FFTs. Another technique is to automatically scale the outputs of each stage by a factor of  0.5, which would not allow the outputs to grow. 
 Details about the observations are given in Table 1. The Piercing Lat. (Lon.) in the table is the center latitude (longitude) of the observation area of the corresponding instrument. 
 -$"%! +($#  $"%! +   "(    ' # '  #!. 
 The mount has operated inwinds upto80mph, and thedesign issuch that 125-mph winds should not cause damage. TheAiV/APS-10.-In spectacular contrast with theforegoing isthe more recent oftwo alternative scanner designs for the AN/APS-10 navigational radar (Fig. 9.16); itisairborne and weighs about 13lb. 
 64 MAX CLOSING FOR CLOSING TARGETS NEGATIVE  RANGE RATE   THEN THE MINIMUM VALUE OF 02&   F2 MIN  WHICH IS UNAMBIGUOUS IN VELOCITY   IN BOTH MAGNITUDE AND SENSE  IE  POSITIVE AND NEGATIVE   IS   F6 6 624 4 G MIN  MAX   MAX      CLOSING OPENING L   WHERE 6G IS THE UPPER LIMIT FOR GROUND MOVING TARGET REJECTION  6 REFERS TO THE SPEED   OR THE MAGNITUDE OF THE RANGE RATE&)'52%  #LUTTER AND CLUTTER 
 Inhigh- power systems orunpressurized airborne systems, where line breakdown isapossibility, the strain isofcourse higher forahigh VSWR. Aratio of1.5means that foragiven breakdown gradient, 33percent less power can bedelivered tothe load than could bedelivered inamatched load. This can bealimitation. 
 17.3, the length ofthe flip-flop being slightly less than that oftheflip-flop atthetransmitter sothat video signals arealways excluded from thedecoder. Toproduce themechanical rotation, the decoded pulses first actuate ascaling circuit, such asthat ofFig. 13.20, which reduces their frequency totwice that appropriate toasynchronous motor. 
 OCEAN MEASUREMENTS OF CAPILLARY WAVE SPECTRA ARE ESPECIALLY DIFFICULT TO PERFORM   &OR A GRAVITY WAVE  THE FREQUENCY  F AND THE WAVENUMBER  + ARE RELATED BY THE DIS 
 Very-short-wavelength radars are useful for probing newly developing clouds, while longer-wavelength radars are necessary for the study of severe storms. Researchers often need a wide range of these capabilities simultaneously. The capabilities desired of multiple-parameter meteorological radars are presented in the collection of papers edited by Hall.6 From the radar engineering standpoint, the challenge is considerable, requir- ing radar designers to develop fully coherent, polarization-diverse, and wavelength-diverse radars. 
 Thevarious electrodes aresoshaped that strong electron lens actions areproduced bythefieldsat thetwo gaps. Adjust- ment offocus ismade bycontrolling thepotential ofthefocus electrode. Magnetic focusing isaccomplished bymeans ofalongitudinal mag- netic field ofcircular symmetry which increases inintensity fromthe center totheedge ofthetube and thus has radial components that help provide the focusing action. 
 Thus the time- and frequency-measurement accuracies may  be made independent of one another.  For the privilege of independently controlling the time and frequency accuracy with a  periodic waveform, additional peaks occur in the ambiguity diagram. These peaks cause  ambiguities. 
 This is the blip-scan ratio and is the probability of detecting a target at a particular  range. altitude, and aspect. The head-on and tail-on are the two easiest aspects to provide in  field measurements. 
 FIG. 18.1 AN/FPQ-6 C-band monopulse precision tracking radar installation at the NASA Wal- lops Island Station, Va. It has a 29-ft-diameter antenna and a specified angle precision of 0.05 mrad rms. 
 4.2c is more typical of aircraft-detection radar, while  the waveform or Fig. 4.2b might be more applicable to a radar whose primary function is the  detection or extraterrestrial targets such as ballistic missiles or satellites. Ambiguities in the  measurement of doppler frequency can occur in the case of the discontinuous measurement of  Fig. 
 They arenot, however, usually made greater than a few microseconds because ofthebulkiness oflonger delay lines. Amethod ofdecoding thethree pulses isshown inthe upper part of Fig. 17.3. 
 APERTURE PRODUCT AVAILABLE 4HESE RADARS HAVE THE ABILITY TO MEASURE HIGH RESOLUTION WINDS CONTINUOUSLY  WHICH PERMITS THE OBSERVATION OF SMALLER SCALE TEMPORAL AND SPATIAL WIND 
 One of the fundamental theorems of antenna theory concerns reci­ procity. It states that under certain conditions (usually satisfied in radar practice) the transmit­ ting and receiving patterns of an antenna are the same.1 Thus the gain definitions apply equally  well whether the antenna is used for transmission or for reception. The only practical distinc­ tion which must be made between transmitting and receiving antennas is that the transmitting  antenna must be capable of withstanding greater power. 
 A high posi - tional correlation increases the integrity of the observation, particularly as speed and  course measurements can also be used in the comparison. Lack of any correlation can  also give the user information that may be helpful. If only radar data is received, it may  be that the target is not fitted with AIS, which means it could be a small craft, floating  debris, or ice. 
 Res ., vol. 70, pp. 2319–2324, 1965. 
 Friis, H. T.: Noise Figures of Radio Receivers, Proc. IRE, vol. 
 The narrow beam provided byamicrowave radar isimportant inall these cases. Inground radar, anarrow beam permits thedetailed resohl-. 184 THEGATHERING ANDPRESENTATION OFRADAR DATA [S~C.6.11 tion ofacomplicated airsituation, and also isbeneficial inreducing the effects ofground clutter. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 to the direction of scan. 
 D. L. Evans et al., “Radar polarimetry: analysis tools and applications,” IEEE Trans. 
 74.Nathanson, F.E.:..RadarDesignPrinciples," McGraw-Hili BookCompany, NewYork,1969, chap.4. 75.Hansen, V.G.:Constant FalseAlarmProcessing inSearchRadars, International Conference on Radar-Present andFuture,Oct.23-25,1973,pp.325-332, lEEPublication No.105. 76.Hubbard, J.V.:DigitalAutomatic RadarDataExtraction Equipment, J.Brit.IRE,vol.26, pp.397-405, November, 1963.. 
 TION SUMMARIES ARE ALSO IN THE  -ANUAL OF 2EMOTE 3ENSING  2EADERS REQUIRING MORE  DETAILED INFORMATION SHOULD CONSULT THESE BOOKS  £È°ÓÊ *, 
  =       4WO 4ONE )NTERMODULATION $ISTORTION )-$   4WO TONE INTERMODULATION DISTORTION  IS ALSO IMPORTANT IN RECEIVER APPLICATIONS 4ESTING IS PERFORMED WITH TWO SINUSOIDAL INPUT  SIGNALS OF UNEQUAL FREQUENCY AND LEVELS SET SUCH THAT THE SUM OF THE TWO INPUTS DOES NOT EXCEED THE !$ CONVERTER FULL 
 ERROR SENSITIVITY OF THE DIFFERENCE SIGNALS NORMALIZED BY THE SUM SIGNAL 4HE DETECTED $ INFORMATION IS A BIPOLAR VIDEO WHERE THE ERROR INFORMATION IS CONTAINED IN  THE SINUSOIDAL ENVELOPE 4HIS SIGNAL IS SEPARATED INTO ITS TWO COMPONENTS  AZIMUTH 
 H., D. W. Burgess, and R. 
 Dwork, B. M.: Detection of a Pulse Superimposed on Fluctuation Noise, Proc. IRE, vol. 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 24.6  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 being the most common), string balls, rope, and semiconductors.3,13 Chaff consists of  dipoles cut to approximately a half wavelength of the radar frequency. It is suitably  packaged to contain a broad range of dipole lengths designed to be effective over  a wide frequency band. 
 .........::::5° Scanner Scan rate .......... .....30rpm Tilt angle ................... ..0 °to–180 Triangle ................. 
 Bris the signal bandwidth. Tsis the azimuth accumulation time. In the phase modulation, the constant phase ϕ0does not affect focus, and the spatial variance of a2and a3(related to the spatial variance of the Doppler parameters) is analyzed below. 
 One approach that has been successful in achieving the maximum MTI system  performance attainable within the limits imposed by system and clutter instabilities FIGURE 2.80  Pulse compression with MTI: ( a) ideal but difficult-to-achieve combination  and ( b) effect of oscillator on transmitter instabilities FIGURE 2.81  Practical MTI pulse-compression combination ch02.indd   76 12/20/07   1:46:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 E. P. Schelonka, “Adaptive control technique for on-axis radar,” in Int. 
 One of the simplest conical-scan antennas is a parabola with an offset rear feed rotated  about the axis of tlie reflector. If the feed maintains the plane of polarization fixed as it rotates,  it is called a rtlrratittg feed. A rotatir~g feed causes the polarization to rotate. 
 This  integral cannot be readily evaluated in the general case. However, approxin~ations to the solu-  tion may be had by dividing the area about the antenna aperture into three regions as deter-  mined by the mathematical approximations that must be made. The demarcations among these  three regions are not sharp and blend,one into the other. 
 ~0.01  :;:  .E  (I)  a::: I I  / 4Receiver noise  ( monopulse)  10 100  Relative radar ronge 1,000  Figure 5.14 Relative contributions to angle tracking error due to amplitude fluctuations, angle Huctua­ tions, receiver noise, and servo noise as a function or range. (A) Composite error for a conical-scan or  sequential-lobing radar; (B) composite error for monopulse. TRACKING RADAR 171  scatterers will change and a new resultant is obtained as well as a new angular measurement. 
 SIONS IS REDUCED -EASUREMENTS WITH TACTICAL AIRCRAFT SHOWED THAT FOR A n BISTATIC ANGLE  PEAK GLINT EXCURSIONS COULD BE REDUCED BY A FACTOR OF  OR MORE  WITH MOST OF  THE EXCURSIONS CONTAINED WITHIN THE PHYSICAL EXTENT OF THE TARGET  4HIS REDUCTION CAN  BE EXPLOITED IN A SEMI 
 As a result, the radiated field will be somewhat  elliptical, rather than purely circular. The hybrid-polarity architecture is self-calibrating  and, therefore, relatively robust in response to such imperfections. In brief, under the  condition that s  0 HH = s  0 VV, the mean signal level in the two receive channels should be  equal. 
 B. Wiesner: Application of Correlation Analysis to the  Detection or Periodic Signals in Noise, Proc. IRE, vol. 
 Theanalogsignalsfromthephasedetectors areconverted into10-bit digitalwordsbyAIDconverters. Therangecoverage, whichtotaled47.5nmiintheoriginal implementation, isdividedintol~nmiintervals andtheazimuth intoi-degree intervals, fora totalof365,000 range-azimuth resolution cells.Ineachi-degree azimuth interval (about one-half thebeamwidth) tenpulsesaretransmitted ataconstant prf.Onreceive,thisiscalleda coherent processing interval(CPI).Thesetenpulsesareprocessed bythedelay-line canceler andthedoppler filter-bank, toformeightdopplerfilters.Thus,theradaroutputisdividedinto approximately 2,920,000 range-azimuth-doppler cells.Eachofthesecellshasitsownadaptive threshold. Inthealternate l-degree azimuth intervals another 10pulsesaretransmitted at adifferent prftoeliminate blindspeedsandtounmask movingtargetshiddenbyweather. 
 LINE COMPONENTS OR LUMPED 
 STATE TRANSMITTERS THAT SUPPLY CONTINUOUS WIND PROF ILES UP TO  KM FOR  IMPROVED WEATHER FORECASTS AND CURRENT UPPER AIR WIND INFORMATION FOR AVIATION APPLICATIONS  )T IS IMPORTANT TO RECOGNIZE THAT THREE 
 The physically small antenna sizes at millimeter wavelengths result in high gain, but the . 562 INTRODUCTION TO RADAR SYSTEMS  small area means that less of the echo energy will be collected by the antenna. A large antenna  aperture is important for long-range surveillance radars, as was shown by Eq. 
 PLACED RETURNS  'ENERALLY TO ADDRESS TIME 
 The active-switch  modulator permits greater flexibility and precision than the line-type modulator. It can  provide excellent pulse shape, varying pulse durations, and pulse repetition frequen - cies, including mixed pulse lengths and bursts of pulses with close pulse spacings. Microwave tubes and their high-voltage switches can sometimes produce an  unwanted arc discharge that effectively places a short circuit across the power sup - ply and/or modulator delivering power to the tube. 
 Aerosp. Electron. Syst. 
     PP n    2 & #ONTRERAS  7 * 0LANT   7  # +ELLER  + (AYES  AND * .YSTUEN  h%FFECTS OF  RAIN ON +U BAND  BACKSCATTER FROM THE OCEAN v * 'EOPHYS 2ES  VOL   NO #  PP n    * 0 (ANSEN  h(IGH RESOLUTION RADAR BACKSCATTER FROM A RAIN DISTURBED SEA SURFACE v PRESENTED AT  )3.2 
 LIKELIHOOD ESTIMATE OF SI  THE  NOISE POWER PER PULSE 4HE RATIO DETECTOR WILL DETECT TARGETS EVEN THOUGH ONLY A FEW  RETURNED PULSES HAVE A HIGH SIGNAL 
 Bush: Constrained Improvement MTI Radar Processors. IEEE Tra11s ..  ml. 
 !IR 3EARCH  !CQUISITION AND 4RACK -EDIUM 02&  )T MAY BE INSTRUC 
 vol. 47.  rr 740 755. 
 2.3). The second detector and video amplifier are assumed  to form an envelope detector, that is, one which rejects the carrier lrequency but passes the  modulation envelope. To extract the modulation envelope, the video bandwidth must be wide  enough to pass the low-frequency components generated by the second detector, but not so wide  as to pass the high-frequency components at or near the intermediate frequency. 
 Inthe horizontal plane this geometry, called the stretched PPI’(Fig. 6.6), isuseful principally incon- nection with the control from a remote point ofaircraft approach- ingalanding, orships navigating achannel. The stretching, done inadirection perpendicular tothe desired course, aids greatly inde- tecting slight deviations therefrom. 
 The second is the matched filter described  by Eq. (10.15) when the input is white noise and a signal whose spectrum is S(f )/Ni(f ).  10.3 CORRELATION  DETECTION'^^^  Equation (10.18) describes the output of the matched filter as the cross correlation between the  input signal and a delayed replica of the transmitted signal. 
 FED REFLECTORS WHERE LIMITED ELECTRONIC SCAN SUFFICES !DVANTAGES AND !PPLICATIONS OF THE 2ADAR 2EFLECTOR !NTENNA  )N THE PREVIOUS  PARAGRAPH  THE PROLIFERATION OF %3! ANTENNAS IN MODERN RADAR SYSTEMS IS LINKED TO THE #HAPTER . £Ó°Ó  2!$!2 (!.$"//+  DRAMATIC 42 MODULE COST REDUCTIONS AND TECHNOLOGY IMPROVEMENTS 4HE IMPROVED PER 
 Introduction Wide angle synthetic aperture radar (WASAR) receives echo data from a large angle. Advances in synthetic aperture radar (SAR) technology have enabled coherent sensing of WASAR. Circular SAR (CSAR) is a speciﬁc case of WASAR whose track is circular. 
 Any use is subject to the Terms of Use as given at the website. Radar Cross Section.  RADAR CROSS SECTION  14.376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 The resulting imaginary part of the propagation constant attenuates waves traveling  through the material. Most of the commercial versions of Dällenbach absorbers are flexible and can be  applied to modestly curved surfaces. 
 Shirokodiapa­ zommykx Antenn iFidernykx Ustroistv" (Design ofLenses, Scanning Antennas, Wideband Antennas. andTransmission Lines.)Energiya, Moscow, 1973,pp.81-82. 139.Lewis, B.L.:3600Azimuth Scanning' Antenna Without Rotating RFJoints. 
 Duringthistime,RFenergyleaksintothereceiver. Thisis calledthespike-leakage energy.From1to10ergsofspike-leakage energymightberequired to burnoutmicrowave crystaldiodes.Theamountofenergycontained withintheremainder of thepulseaftertheinitialspikeisusuallysmallandisnotasseriousasspikeleakage. Whenasolid-state duplexer isusedorwhenasolid-state limiterfollowstheTRswitch, thereneedbenoinitialspikeandburnout isnotdetermined bythe pulse energy.Burnout due topulseswithout aninitialspike,butgreaterthanaboutI~sinduration, isdetermined primarily bythepeakpower.16(Theburnout conditions forpulses1~sorgreaterisessentially thesameasforCW.)Crystaldiodescanwithstand severalwattsormoreofpeakpowerunder pulseconditions. 
 Remote Sens. 2017 ,55, 2739–2750. [ CrossRef ] 14. 
 NUMBERED BEAMS  SO THAT RETURNS IN BEAM PAIRS ARE PROCESSED SIMULTANE 
 PULSE DOPPLER RADAR  4.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 instantaneous dynamic range is preferable. If saturations occur in a range gate during  an integration period, an option in a multiple-range gated system is simply to blank  detection reports from that gate. When a MTI filter is not used, the doppler filter bank  for each range gate can be examined to determine if there are any detections due  to spurious signals from large clutter, with subsequent editing of these detections if  the measured clutter-to-noise ratio exceeds the dynamic range. 
 Ayliffe, “Track initiation and nearest neighbors incorpo - rated into probabilistic data association,” J. Elec. Electron. 
 There exists adequate technology to either  side of the millimeter wave spectrum: at the longer wavelengths (microwaves) and at the  shorter wavelengths (iR and visual). Also, there are compone~it developments at millimeter  wavelengths which indicate that technology is not basically limited. For example, high power  has been demonstrated with the gyrotron, or electron cyclotron maser, comparable to tliat  achieved with microwave devices. 
   YET BARELY HALF  THAT OF THE " 
 TO 
 STEERING PHASES ARE GREATLY SIMPLIFIED BY THE ADOP 
 FORMANCE &OR EXAMPLE  AN !TLANTIC COAST VESSEL TRAFFIC CONTROL RADAR LOCATED NEAR THE ENTRANCE TO THE $ELAWARE "AY OBSERVED A REDUCTION IN DETECTION RANGE FROM  TO  KM 3OMETIMES SHIPS CAN BE SEEN VISUALLY FROM THE RADAR TOWE R BEFORE THEY CAN BE  OBSERVED ON THE RADAR SCREEN 4HE REDUCTION IN THE RADAR DETECTION RANGE USUALLY LASTS SEVERAL HOURS AND OCCURS OFTEN WHEN FOG IS PRESENT  ! SUBREFRACTIVE LAYER OF THE TROPOSPHERE WOULD CAUSE THE PROPAGATING ENERGY TO  BEND UPWARD OR AWAY FROM THE %ARTHS SURFACE  THEREBY LEADING TO DECREASED DETECTION RANGES AND SHORTENED RADIO HORIZONS 3UBREFRACTIVE LAYERS MAY BE FOUND AT THE %ARTHS SURFACE OR ALOFT )N AREAS WHERE  THE SURFACE TEMPERATURE IS GREATER THAN  #ELSIUS  AND RELATIVE HUMIDITIES ARE LESS THAN  IE  LARGE DESERT AND STEPPE REGIONS   SOLAR HEATING WILL PRODUCE A VERY NEARLY HOMOGENEOUS SURFACE LAYER  OFTEN SEVERAL HUNDREDS OF METERS THICK "ECAUSE THIS LAYER IS UNSTABLE  THE RESULTANT CONVECTIVE PROCESSES TEND TO CONCENTRATE ANY AVAIL 
 !"   
 However, this problem is not severe in practice, since multiple  targets in a single beamwidth are usually a transient phenomenon. The accuracy of the range measurement improves as the FM slope increases since  the observed frequency differences can be more accurately measured. The FM slope is,  however, limited by clutter-spreading considerations, since during the FM periods, the  clutter is smeared in frequency and can appear in frequency regions normally clear of  clutter.57 A no-FM, FM-up, double FM-up scheme is recommended to prevent desired  targets from competing with main-beam clutter. 
 Intheearlyversions ofthephase-comparison monopulse radar,theangularerrorwas determined bymeasuring thephasedifference between theoutputsofreceivers connected to eachantenna. Theoutputfromoneoftheantennas wasusedfortransmission andforprovid­ ingtherangeinformation. Withsuchanarrangement itw.asdifficult toobtainthedesired aperture illuminations andtomaintain astableboresight. 
 The only practical distinc-  tion which must be made between transmitting and receiving antennas is that the transmitting  antenna rnusibe capable of withstanding greater power.  I '.  Effective apertuve. 
 OUT DURING THE TRANSMITTED PULSE 0HASE RUN 
 PROFILING LIDAR  AND IN SOME 
 The shape of the curves in Figure 15.1 indicates that  the sea wave system is sharply peaked, so it should be possible to get a rough idea of  the behavior of the major waves on the surface by taking the values of period  (1/ f  )  and wavelength  (2p /K) defined at the spectral peak. These values are assigned to a  wave satisfying the dispersion relation Eq. 15.1 and having a phase velocity C = 2p f /K  equal to the wind speed U. 
 Whentheechofromtheseacanbe.modeled asthatfromanumberofindependent, random scatterers, withnooneindividual scatterer producing anechoofmagnitude commensurate withtheresultant echofromallscatterers, thentheamplitude fluctuations oftheseaechois described bythegaussian probability densityfunction, [Eq.(2.15)].Thestatistical fluctuations oftheenvelope vofsuchanechoattheoutputoftheenvelope detector intheradarreceiver isgivenbytheRayleigh probability densityfunction (pdf),whichis , .2v'(v2)p(v)=2exp-2 'J,(J .(J where (Jisthestandard deviation oftheenve~ v,whichfortheRayleigh pdfisproportional tothemeanvalue.(ThemedianvalueisVln2(J.)Clutterwhichconforms tothismodelis calledRayleigh clutter.TheRayleigh pdfappliestoseaclutterwhentheresolution cell,or areailluminated bytheradar,is'relatively large.Experimental datashow,however, thatthis distribution doesnotapplywithahigh-resolution radarwhichilluminates onlyasmallarea ofthesea.Theprobability densityfunction deviates fromRayleigh whentheareailluminated bytheradarhasadimension (usually thedimension determined bythepulsewidth)which iscomparableto,orsmaller'than;thewaterwavelength.! JTheredoesnotseemtoexistany singleanalytical formofprobability densityfunction thatfitsalltheobserved data.Theactual formofthepdfwilldependonthe-sizeofthe'radar.resolution cellandtheseastate.An example ofseaclutter·statistics isshown:inFig.13.5,whichplotstheprobability thatthe clutterwillexceedtheabscissa, ratherthantheprobability densityfunction. (Thetwoare related,however.)Itisseenthatactualclutterhasagreaterprobability ofalargevalueofsea clutterthandoes'Rayleigh clutter~Stated inotherterms,theactualdistribution hashigher "tails"thantheRayleigh.;This meansthatclutterseenbyahigh-resolution radarwillhavea greaterlikelihood offalsealarm'than·.Rayleigh clutterifthereceiver· isdesigned inthe. RADAR CLUTTER 479  Clutter cross secl~on in dB lo on orb~trory scale  1  - ,,I Figure 13.5 Experimetltal statistics of vertical polarization, X-band sea clutter for two sea states. 
 Although the elevation- angle-error-detector output has large indicated angle errors, it is monitored to observe  whether or not the target is maneuvering upward through the beam. A target rising  through the beam will cause a positive angle-tracking error indication and the closed- loop elevation tracking resumes. A very effective and direct approach to multipath-error reduction is to use a very  narrow beam, usually accomplished by operating at short wavelengths such as an 8-mm   (35 GHz or Ka band) region with the usual microwave-tracking aperture size.13,25,26, TARGETS TARGETS TARGETS(a) TA RGET SEP ARATION –0.30 ANTENNA BEAMWIDTH (b) TA RGET SEP ARATION –0.75 ANTENNA BEAMWIDTH (c) TA RGET SEP ARATION –0.85 ANTENNA BEAMWIDTHPROBABILITY DENSITY FIGURE   9.31  Probability distribution of radar pointing when tracking  two targets (where the left target is approximately 1.5 dB larger than the  right target). 
 PERATURE AND ITS TOTAL EFFECTIVE NOISE GAIN OR LOSS 4HE NOISE LEVEL CAN BE SPECIFIED EITHER AS AN RMS POWER IN A SPECIFIED BANDWIDTH OR AS A NOISE POWER SPECTRAL DENSITY 3YSTEM .OISE 4HE SYSTEM NOISE LEVEL IS THE COMBINED ANTENNA AND RECEIVER NOISE  4YPICALLY  THE RECEIVER INPUT NOISE WILL EXCEED THAT OF THE NOISE DUE TO THE RECEIVER ITSELF  SO THAT THE RECEIVER HAS ONLY A SMALL IMPACT ON THE SYSTEM NOISE TEMPERATURE OR NOISE FIGURE 4HUS  WHEN DEFINING DYNAMIC 
 In fact, it is even seen that for ranges  between 55 and 65 nautical miles, the clutter-to-noise ratio exceeds the signal-to-noise  ratio. Thus for these ranges, the radar return is overwhelmed with clutter. FIGURE 26.16  AREPS height versus range coverage for surface-search radar and small missile target— propagation factor ch26.indd   26 12/15/07   4:53:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 TER AND POINT TARGETS IS SKETCHED IN &IGURE  )F THE POINT TARGETS ARE MOVING  THE SUPER 
 A,: "Aerials for Metre arid Decimefre Wave-lengths," Cambridge University Press.  London. 1949. 
 A considerably higher integration can b e achieved using MMICS.  A large advantage is the  reduction of the millimeter -wave connections.  With that there is an increase in the reliability  and a reduction of the line losses. 
   ,AWRENCE  3EPTEMBER    2EF   VOL ))  PP n VOL )))  CHAP    2 :OUGHI  , + 7U  AND 2 + -OORE  h3/52#%3#!4 ! VERY FINE RESOLUTION RADAR SCATTEROM 
 PARAMETER POLARIZATION AND WAVELENGTH  RADAR STUDIES  MULTIPLE DOPPLER RADAR NETWORK STUDIES  AND A NEW GENERATION OF AIRBORNE AND SPACEBORNE RADARS ARE RECEIVING CONSIDERABLE ATTENTION $UAL 0OLARIZATION7AVELENGTH 2ADAR  )T IS CLEAR THAT POLARIMETRIC DOPPLER  RADARS PROVIDE A SIGNIFICANT INCREASE IN THE USEFUL INFORMATION THAT CAN BE OBTAINED FROM METEOROLOGICAL TARGETS 4HE DETECTION OF HAIL AND MORE ACCURATE RAINFALL ESTI 
 MENT ! REASONABLE COMPROMISE MAY BE REACHED BY ADDING ONE TIME 
 Assessment of the performance of ASV Mk. VIA was reported by ASWDU in February 1945 [ 10]. Compared with earlier trials of ASV Mk. 
   %,%#42/.)# #/5.4%2 
 13.6.  The Doppler frequency shift. The expression for the doppler frequency shift given previously  by Eq. 
 Smith and G. Phillips, Power Klystrons Today , New York: John Wiley, 1995, Sec. 7.2.3. 
 So in  radar, as distinct from speech broadcasting (where we  usually have a continuous-wave carrier), we can use quite  small valves and very economical circuits, overloading  them tremendously for minute portions of time. The  longer we make our pulses—that is, the greater the  pulse-width—and the greater the PRF, the nearer we  get to a continuous-wave state of working, and so we  need bigger apparatus. In the majority of radar pulse  systems the interval of time during which the pulse is  on is infinitesimal compared with the long interval of  time between pulses. 
 The visible and infrared (IR) radiometer covered a single swath 1800 km wide, symmetrical about the nadir. Seasat-A collected data until Oct. 9, 1978, when a short circuit developed at the slip rings between the solar array and the power distribution bus. 
 The load resistances encountered inpractice areapproximately 500ohms orhigher. Insuch acase, theload and the line arematched through apulse trans- former. The voltage step-up ratio ofthepulse transformer, n,ischosen tomake n2=RL/Zo. 
 RANDOM NOISE WAVEFORMS WERE ALSO POSSIBLE $IGITAL  TECHNOLOGY  HOW 
 Despite this precaution, the leakage power through aTR tube shows aninitial spike (Fig. 11.16) which precedes the “flat” region ofconstant leakage power. For rapid deionization ofthe gaponeconstituent ofthegasmust have anelectron affinity. 
   PP n  -ARCH    * * 3CAVULLO AND & * 0AUL   !EROSPACE 2ANGES )NSTRUMENTATION   0RINCETON  .* $ 6AN .OSTRAND  #OMPANY    " $ 3TEINBERG  ET AL  h&IRST EXPERIMENTAL RESULTS FOR THE 6ALLEY &ORGE RADIO CAMERA PROGRAM v  0ROC )%%%  VOL   PP n  3EPTEMBER    " $ 3TEINBERG  h2ADAR IMAGING FROM A DISTRIBUTED ARRAY 4HE RADIO CAMERA ALGORITHM AND EXPERI 
 ~ 0.5 -2 3  Angular frequency, w  (a) 4  -:\,[  1/T  (b) 5  ·g O __ L______.l._~1--~~~-~  ~ 0 1/T  (c)  r:\,L  1/T  Frequency  (d) Figure 4.14 (a) Three-pole Chebyshev low-pass filter  characteristic with 0.5 dB ripple in the passband; (b-d)  delay-line filter ·;haracteristics derived from (a). (After  White.12) . 114 INTRODUCTION TO RADAR SYSTEMS  t 1  Deloy T f--+--i  -1  0.61 Delay T Vout  Deloy T  Figure 4.15 Form of the delay-line filter required to achieve the characteristic of Fig. 
 53, pp. 1428-1437, October 1965. 18. 
 R. Meteorol. Soc. 
 An echo  fluctuation of this type will be .referred to as scan-to-scan fluctuation. The probability- • I L . THE RADAR EQUATION 47  (it:nsity function for the cross section er is given by tl1e density function  p( r;) = 1 exp ( -a ) a., a.,. 
 M. Roberts, “OTH radar receiving system design using synoptic  HF environmental database,” Proc. 5 th Int. 
 33. J. H. 
 The gyrotron bunching  operation also can be obtained at harmonics of the cyclotron frequency, but there can  be problems with higher circuit losses and competition with modes operating at lower  harmonics so that most high-power gyrotrons operate at the fundamental frequency or  its second harmonic.33 Because the frequency of a gyrotron is determined by the magnetic field and  not by the size of the fast-wave structure, the structure can be large, and it is then  possible to generate quite high power at millimeter-wave frequencies. The large  magnetic fields needed for millimeter-wave gyrotrons often have to be generated by  superconducting magnets. The gyrotron with a single cavity operates as an oscillator. 
 pp.3263.'7.May.1975.(Alsoavailahle inrer.I.) 20.Headrick. J.M..andM.I.Skolnik: Over-Ihe-Horizon RadarintheHFBand. I'I'/IC.IEfE.vol.62. 
 When (} = 0, the  <loppler frequency is maximum. The doppler is zero when the trajectory is perpendicular to  the radar line of sight (0 = 90°).  The type of radar which employs a continuous transmission, either modulated or unmod­ ulated. 
 POWER APPLICATIONS AT MILLIMETER 
 SPEED COMMUNICATION NETWORKS )NCLUDED IN THIS CLASS ARE HIGH 
 For example, it is commonly noted that when viewed on  an A scope (signal amplitude versus range), the appearance of sea clutter depends  strongly on the size of the resolution cell, or radar footprint.  For large cells, it  appears distributed  in range and may be characterized by a surface-averaged cross  section with relatively modest fluctuations about a mean value. As the size of the  resolution cell is reduced, clutter increasingly appears to contain sequences of iso - lated target-like, or discrete , returns that vary in time. 
 SYNCHRONOUS ORBITS IS GOOD TO ABOUT   CM  BASED ON THE $ELFT MODEL !S SUN 
 At these frequencies, the reflection coefficient on  scattering from the earth’s surface can be very large, especially over water, so the  constructive interference between the direct signal and the surface-reflected signal can  increase significantly the range of a VHF radar. Sometimes this effect can almost dou - ble the radar’s range. However, when there is constructive interference that increases  the range, there can be destructive interference that decreases the range due to the deep  nulls in the antenna pattern in the elevation plane. 
 BER OF 02&S MAY BE REQUIRED TO OBTAIN A SATISFACTORY PROBABILITY OF SUFFICIENT DETECTIONS TO RESOLVE THE RANGE AND DOPPLER AMBIGUITIES 4HE MULTIPLE 02&S MOVE THE RELATIVE LOCATION OF THE CLEAR REGIONS SO THAT ALL 
 TIME PERFORMANCE OF THE SYSTEM -ICROWAVE INPUTS n '(Z  ARE MIXED TO A  -(Z INTERMEDIATE FREQUENCY )&  FOR AMPLIFICATION ! PROGRAMMABLE OSCILLATOR  WHICH CAN CORRECT FOR FIRST 
 CLUTTER RATIO AT THE INPUT TO THE FILTER BANK  COMPUTED AS A FUNCTION OF TARGET DOPPLER FREQUENCY 4HIS DEFINITION DOES NOT INCLUDE ANY DOPPLER AVERAGING ACROSS THE INDIVIDUAL  FILTERS  AND THE DEFINITION DOES NOT PROVIDE A SINGLE FIGURE OF MERIT FOR A RADAR DOP 
 The loss in gain and the magnitude of the grating lobe are functions of the fractional  subarray beamwidth that has been scanned as a result of the change in frequency. The  results may be expressed in terms of the bandwidth factor K (referred to as the subarray  broadside beamwidth ). Figure 13.28 shows these values as functions of K for a scan of 60 °. 
 11. A. N. 
 2. Synchronize ac-dc and dc-dc power conditioners† to harmonics of the PRF. 3. 
 Also,theantenna gaincanbegreateratthehigherfrequencies, afactor oftenfavoring theradarwhenconfronted withjamming, asseenbyEqs.(14.28)and(14.30). Furthermore, atthehigherfrequencies theantenna sidelobe levelscanbelower,making it lJlorcdiflicull forsidcJohe jamming. Ilowever, lheadvantages ofoperaling againsljamlllers al thehigherfrequencies arcbalanced inpartbythedisadvantages ofthehigherfrequencies, especially ahove1.hand,forlong-range air-surveillance radar. 
 169  in monopulse, 164  Automobile, radar cross section of, 44  Az-el mount. 271  B sandwich radome, 267  Balanced duplexers, 360-36 1  Balanced mixers, 348-349  BAM. 510,  Bandwidth:  CW radar, 75-76  efkctive. 
 Near the output, on both sides of the output coupling, the ring is firmly ,  ,,,b attached to the cavity wall, but is unattached otherwise. By deforming the ring inward from  mechanical motion applied to the free-hanging ends of the ring, the tuning of the cavi:y is  changed. The Raytheon QKH 1763 X-band coaxial magnetron tunes in this manner over a  100-MHz range at rates up to 200 Hz. 
 75. Brown, R. P.: Radar Height Finding, chap. 
 61.  pp. 143 - 144. 
 In general, the attribute that makes GaAs an at- tractive technology is that the GaAs FET can be fully integrated with the passive circuitry that is necessary to provide the biasing, loading, filtering, and switching functions that are necessary for multistage transceiver module designs. As a re- sult of fundamental device limitations, however, this approach is not envisioned . as a cost-effective alternative for module designs that require power outputs ex- ceeding 25 to 30 W. 
 Or the scatterers might be detached from the underlying surface, as in the plumes emitted at the crests of breaking waves, and move at speeds much greater than the orbital speeds.48 At higher radar frequencies and in strong winds, the possibility of scattering from spray, advected by the wind field above the surface, must be considered. All this complex motion shows up in a doppler shift imparted to the scattered electromagnetic wave. Surprisingly few measurements of microwave clutter spectra for real seas have been reported in the literature, and those few that exist can be separated into aircraft measurements of the spectral shape alone49'50 and fixed-site shore measurements showing a shift in the spectral peak.51'52 All these studies were performed at relatively low grazing angles (less than 10°), although Valenzuela and Laing include a few measurements up to 30°. 
 In fact, these devices offer an attractive alternative to tube op- eration at the lower frequencies. At higher frequencies, and especially for microwave phased array applications where a physically small module with transmit and receive functions is neces- sary, the gallium arsenide field-effect transistor (GaAs FET) and its associated batch-processed monolithic microwave integrated circuitry (MMIC) can be used. GaAs FETs are well established as low-noise devices up to 60 GHz;3 and, with individual cell-combining techniques,4 GaAs FETs can be used as power ampli- fiers in the 1- to 20-GHz range. 
 J. Plaut, and G. Picardi, “Radar soundings of the ionosphere  of Mars,” Science , vol. 
 24.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 Electronic   Counter-Countermeasures A. Farina Analysis of Integrated Systems   SELEX Sistemi Integrati 24.1 INTRODUCTION Since World War II, both radar and electronic warfare (EW) * have achieved a very  high state of performance.1,2 Modern military forces depend heavily on electromagnetic  (EM) systems for surveillance, weapon control, communication, and navigation; thus  access to, and control of, the EM spectrum is vital. Electronic countermeasures (ECM)  are likely to be taken by hostile forces to degrade the effectiveness of EM systems.3–7  As a direct consequence, EM systems are more and more frequently equipped with so- called electronic counter-countermeasures (ECCM) to ensure effective use of the EM  spectrum despite an enemy’s use of EW actions. 
 1971. 35.Mutton, J.0.:Advanced PulseCompression Techniques, IEEENAECON '75Record,pp.141-148. 36.Welti,G.R.:Quaternary CodesforPulsedRadar,IRETrans.,vol.IT-6,pp.400-408, June,1960. 
 Tile Luneburg principle may also be applied to a two-dimensional lens which generates a  fan bean1 in one plane. In the geodesic analog of a two-dimensional Luneburg lens the  variation iri dielectric constant is obtained by the increased path length for the RF energy  traveling in ttie TEM mode between parallel The result is a dome-shaped parallel-  plate region as shown in Fig. 7.22. 
 Another consideration is the plane of polarization of the electromagnetic energy.  For targets with one large area dimension such as a pipe, the radar cross-scattering  section will be larger when the polarization vector is in line with the pipe. This means  that any area that is surveyed with, say, parallel dipoles must be surveyed in orthogonal  directions to ensure that no targets are missed. 
 D. C. Cross and J. 
 The used measuring system measures complex voltages or power waves ( Watt  ).  Therefore  it is favourable to describe the behaviour of the object by its complex scatt ering matrix [ Sc].   The measuring system doesn’t have direct access to the object, as is obvious to see in Figure  11.6. 
 likely to be known with accuracy in operational situations and that hence it is useless to seek better accuracy for any factor. Although there is some basis for this viewpoint, the overall accuracy will be unnecessarily degraded if the accu- racy of all the factors in the equation is deliberately reduced. Therefore it is rec- ommended that range predictions be based on as careful an evaluation of all the factors as is possible. 
 Griffin, J. W., et al.: Ku-Band—The First Year of Operation, IEEE Int. Radar Conf. 
 2,  March, 1964.  143. Skolnik, M. 
 110.Lane.J.A.:RadarEchoesfromClearAirinRelation toRefractive-Index Variations intheTropo­ sphere,Proc.lEE,vol.116.pp.1956-1660. October. 1969. 
 Uniform illumination and no amplitude and phase errors were assumed. The dashed  line in Figure 13.40 shows the antenna pattern for the same array when an interfering  source is present at +21° and amplitude and phase weighting is used to steer a null in  the pattern in the direction of the interfering source. Radar systems can utilize deterministic RF nulling to place nulls in both the trans - mit and the receive antenna patterns. 
 III, Fig. 21.22, p. 1827. 
 F. Knott, “A tool for predicting the radar cross section of an arbitrary corner reflector,” in  IEEE Publ ., IEEE Southeastcon’ 81 Conference , 81CH1650-1, Huntsville, AL, April 6–8, 1981,  pp. 17–20.FIGURE 14.32  Boeing’s mockup of its X-45C unmanned combat vehicle  (Courtesy of the Associated Press ) ch14.indd   43 12/17/07   2:47:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 POWER 
 RACY  A COMPLETELY SATISFACTORY APPROACH REMAINS TO BE DEVELOPED 0OLARIMETRIC MEASUREMENTS BY THE 732 
 21.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 spiral, the logarithmic planar antenna, the Vivaldi antenna, slot antennas, and the expo - nential horn. The impulse response of this class of antennas generally results in a  waveform whose time frequency response is extended (and is similar to a chirp, albeit  with an inconstant amplitude) if the input is an impulse. Examples of nondispersive antennas are the TEM horn, the bicone; the bow  tie; the resistive, lumped element-loaded antenna, and the continuously, resistively  loaded antenna. 
 PRESENT  PROBLEM OF COORDINATE REGISTRATION UNCERTAINTIES IN THE RAY PATH TRAVERSED BY THE  RADAR SIGNALS CAN LEAD TO TARGET POSITIONING ERRORS OF OVER  KM UNDER SOME CIRCUM 
 Withsufficient radarmeasurements thetwo-dimensional seaspectrum canbederived. TheHFradarrepre­ senlsauniquetoolformeasurill~ seaconditions atadistance. Thecostofaradartomeasure seaconditions canbeconsiderably lessthanthecostofanHFradartodetectaircraft.Itis inleresting 10notethatthedevelopment ofsuchacapability wasoriginally notasanattempt tolearnmoreahoutthesea,butwasabyproduct ofattempts toimprove thedetection of targetsinasea-clutter background. 
 WAY ATTENUATION BY CANOPY   AND   PLANT 
 This is particularly of interest when de- signing a small array. Munk and colleagues63'64 have developed a procedure for reducing the varia- tions in impedance with scanning by matching elements with dielectric slabs. Their analytical results show a VSWR of less than 1.5 for scan angles of ±80° in . 
 A. Senior, M. A. 
 OBSERVING SPACE 
 T. Y . Yu, G. 
 The Air Route Surveillance  Radar (ARSR) used for long range air-traffic control is a good example. As one goes  up in frequency, the effect of rain on performance begins to become significant, so the  radar designer might have to worry about reducing the effect of rain at L-band and  higher frequencies. This frequency band has also been attractive for the long-range  detection of satellites and defense against intercontinental ballistic missiles. 
 It is also possible to jointly perform motion compensation through multiple viewing angles to improve compensation accuracy. 4. Experimental Simulation, Measured Data4.1. 
 Thehigh-power klystron mayalsobepulsedwithagridintheelectron gunsodesigned thatthegriddoesnotintercept theelectrons.7.8Suchnonintercepting griddedgunscanswitch theneamwithlow-power modulators. Thistechnique actually usestwocloselyspacedand alignedgrids.Oneisncarthecathode andisatcathode potential. (Intheso-called Unigrid,42 thisgridisphysically placedonthecathode butisproperly passivated topreventemission.) Thesecondgridisthecontrol gridforthebeamcurrent.Itisatapositive potential andis locatedintheshadowofthefirstgrid.Forthisreasonthefirstgridisalsoknownastheshadow qrid.Thepurpose oftheshadow gridistosuppress electron emission fromthoseportions of thecathode whichotherwise wouldbeintercepted bythesecond,orcontrol, grid.Thecathode surface undereachopening ofthefirstgridisdimpled. 
 Thevalueof"mllstbeproperly chosenconsistent withthebeamwidth andsidelobe level.85. Although the Taylor pattern was developed as a realizable approxinlation to the 1)olpli-  Chebyshev, it does not resemble the theoretical equal-sidelobe pattern. Values of ii are not  large so that a Taylor pattern exhibits decreasing sidelobes over most of its range. 
 ELOBE BLANKING LOGIC v  )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS   VOL !%3 
 It may also be thought or as the effective  number of pulses integrated by the postdetection integrator. The improvement with ideal  predetection integration would be equal to n. Examples of the postdetection integration­ improvement factor /i(n) = nEi(n) are shown in Fig. 
 From the spatial characteristics of the color distribution, we can see that Zhongxinhe Road is still the obvious dividing line in the images (with a dark orange color in the upper area), and that the maximum subsidence was 124 mm (on 27 November 2015). The deformation was signiﬁcantly weaker in the bottom part (generally blue-green), with a maximum subsidence of only 48 mm. It can also be seen, from the temporal color variation in Figure 9, that the deformation was rapid subsidence from the initial time to May 2015, with the subsidence velocity decreasing slowly. 
 TARGET AND TARGET 
 The classic Salisbury  screen is the degenerative case of a single sheet. ch14.indd   36 12/17/07   2:47:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 157. Ward, H. R., C. 
 CONTROLLED BY THE RANGE  &)'52%     $IGITAL RANGE TRACKER OPERATION &)'52%     "LOCK DIAGRAM OF A DIGITAL RANGE TRACKER       
 This material has anexponential decay with atime constant ofafew milli- seconds; itisextremely efficient interms oflight intensity. 2.Applications inwhich persistence isneeded tosmooth out the effects offlicker. The best Ameri- ,.5. 
 DENSITY SATELLITE ALTIMETRY v  'EOPHYS  * )NT  VOL   PP n    7 ( & 3MITH AND $ 4 3ANDWELL  h#ONVENTIONAL BATHYMETRY  BATHYMETRY FROM SPACE  AND   GEODETIC ALTIMETRY v /CEANOGRAPHY  VOL   PP n    - - 9ALE  $ 4 3ANDWELL  AND 7 ( & 3MITH  h#OMPARISON OF ALONG 
 (The spt~ere is the limiting case of the prolate spllcroid wlle11  the separation between the two foci becomes zero.) Hence the target position is found with  monostatic radar as the intersection of a ray (defined by the angle of arrival) and tlle surface of  a sphere.  The doppler beat frequencyj; between the scattered and direct signals in the bistatic radar  is proportional to the time rate of change of the total path length of the scattered signal,  where II is the wavelength of the transmitted signal. The doppler frequency shift provides a  means for discriminating stationary objects from moving targets, but it is r~or a measure of the  radial velocity as with the monostatic radar. 
 AP-22, pp. 799 -803,  November, 1974.  109. 
 D. E., Barrick, J. M. 
 In the remainder of the section, the various techniques for detecting targets in clutter will  be reviewed.  MTI. As mentioned, MTI can be used to separate the moving aircraft targets from the  relatively stationary sea clutter. 
 (14.41)566INTRODUCTION TORADAR SYSTEMS Ifthetargetismuchlargerthanthelaserbeam,ascanhappen insomesituations, theradar equationbecomes R2=1!.~!-}2!!)_ c~~c/J max 3211pI!/B Intheabovethesurface isassumed tobeadiffuse(Lambert) scattcrer withcrosssection (J=4p(1t/4)R2{)~ cos4>,wherep=surface reflectivity and4>=anglebetween thesurface normalandtheincident radarenergy.Theseareonlyapproximate equations. Lossesshould beincluded forpropagation through theatmosphere andinthesystemoptics. Ifaquantum-limited lasermustsearchagivensolidangleninatimets'thefollowing relationship canbeobtained85 nP A A.=const--ave t s(14.4~) Thusthehigherthefrequency (shorter thewavelength) themoredifficull itisforalasato searchalargesolidangleinashorttime.Thelimitedsearchcapability ofalasermeansthat somesortofothercueingsensor,eitherelectro-optical and/orradar,maybeneededinorder forthelaserradartoacquire atarget.86 Thefundamental measurement capabilities ofaproperly designed laserradarcannotbe equalled withamicrowave radar.Thuslaserradarsareusedforthosespecialapplications whereitsexceptional measurement capabilities arerequired, andwheretheneedtosearcha largesolid-angle andall-weather operation arenotimportant. 
 IEEE , vol. 74, pp. 245–269, February 1986. 
 The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results. 209. Sensors 2019 ,19, 516 References 1. 
 (9.6) provides the maximum value of the improvement factor If which is defined as follows: _ signal-to-interference power ratio at the output * signal-to-interference power ratio at the input The signal-to-interference power ratio (SNR)1 at the input is measured at the in- put of an antenna of the array and refers to one echo pulse. The If value corre- sponding to the optimum set of weights of Eq. (9.6) is40 C7M-1S**-7Jssr »» The If is better suited than the cancellation ratio, adopted in the SLC, to repre- sent the performance of the adaptive array. 
 Intheparallel-fed arrayofFig.8.2.theenergytoberadiated isdivided between the elements byapowersplitter. Whenaseriesofpowersplitters areusedtocreateatree-like structure. asinFig.8.2.itiscalledacorporate feed,sinceitresembles (whenturnedupside down)theorganization chartofacorporation. 
 Amodification ofthehelixknownasthering-bar circuithasbeenusedinTWTstoachievehigherpowerandefficiencies between 35aild50 percent.11.12TheRaytheon QKW-1671A, whichutilizesaring-bar circuit,hasapeakpower of160kW,adutycycleof0.036,"puisewidth of70~s,gainof45dB,anda200MHzband­ widthatLband.Thistubeissuitable forair-search radar.SimilarTWTshavebeenusedin phased-array radar.TheAirForceCobraDanephased-array radar,forexample, uses96 /Gun Attenuation Cathode LOde ~ cOllector\ Heale'~rr-----l~~--~ Electron.J It(interaction region) II beam tRF . RF input. .:'..' output Figure6.11Diagrammatic representation orthetraveling-wave tube.. 
 TANEOUS DYNAMIC RANGE AND IS THE LINEAR REGION ABOVE THERMAL NOISE OVER WHICH THE RECEIVER AND SIGNAL PROCESSOR OPERATE BEFORE ANY SATURATION CLIPPING  OR GAIN LIMITING OCCURS )F SATURATIONS OCCUR  SPURIOUS SIGNALS THAT DEGRADE PERFORMANCE MAY BE GENER 
 A  typicrtl radar for tile dctcction of aircraft at ranges of 100 or 200 nmi might employ a peak  power of the order of a megawatt, an average power of several kilowatts, a pulse width of  several microseconds, and a pulse repetition frequency of several hundred pulses per second.  The waveform generated by the transmitter travels via a transmission line to the antenna,  where it is radiated into space. A single antenna is generally used for both transmitting and  receiving. 
 522-527, July, 1970.  53. Davenport, W. 
 171-178, February,  1969.  67. Setter. 
 Lobing. however. is not as pronounced in the case of the round earth: the minima are  · not as deep nor arc the maxima as great since a wave reflected from a curved surface is more  divergent than one reHected from a plane. 
 Galindo, and C. P. Wu: "Theory and Analysis of Phased Array Antennas," Wiley-  Interscience, New York, 1972. 
 The main-beam clutter is filtered out. FIG. 17.5 Clutter-plus-noise-to-noise ratio in range doppler space. 
 8–23, 2004. 89. M. 
 Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 105     11.6 Calibration Standards for Free Space Mea surements   11.6.1  Luneburg Lenses     Figure 11.11  Reflection behaviour from Luneburg lense reflectors.   As mentioned earlier, spheres, which would be favoura ble from their characteristics, have R a- dar backscattering cross- sections, which are too small.  However, reflectors from Luneburg  lenses have similar characteristics with a considerablely larger Radar backscattering cross - section. 
 For example, a radar for detecting low- flying aircraft targets can receive strong ground echoes (clutter) through the sidelobes which mask the weaker echoes coming from low radar cross-section targets through the main beam. Also, unintentional interfering signals from friendly sources (electromagnetic interference, or EMI) and/or intentional inter- ference from unfriendly sources (jammers) can enter through the minor lobes. It is therefore often (but not always) desirable to design radar antennas with sidelobes as low as possible (consistent with other considerations) to minimize such problems. 
 TER POWER  R   X Y  !LERT )N FACT  THIS IS SELDOM  IF EVER TRUE "ACKSCATTERED POWER IS  PROPORTIONAL TO \MAGNITUDE\  NOT MAGNITUDE (ENCE  THE USER MUST ASSURE THAT THE DATA  ARE INDEED MAGNITUDE 
 MONOSTATIC WILL BE USED TO CHARACTERIZE BISTATIC  GEOMETRIES THAT APPROXIMATE MONOSTATIC OPERATION ÓÎ°ÓÊ  "",  / 
 (a) RCS curves of the four targets. ( b) RCS curves of the four targets after denoising. After obtaining the RCS curves of the targets, aspect entropy can be calculated using Equations (1) and (2). 
  AIRFRAME USING EXOTIC MATERIALS  THE LOW 2#3 DEMANDED OF THE & 
 I RE. vol. 35. 
 The limitation on / due to internal-clutter fluctuations can be determined by substituting the appropriate value of ac into Eqs. (15.9) to (15.11). By letting ac = 2(T1A, where av is the rms velocity spread of the clutter, the limitation on / can be plotted for different types of clutter as a function of the wavelength X and the pulse repetition frequency fr. 
 14  One of the causes of diode burnout in radar receivers has been the increased RF leakage  through a conventional duplexer due to aging of the TR tube. When the transmitter fires, the  TR tube breaks down. A finite time, usually on the order of several nanoseconds, must elapse  before breakdown is complete. 
 Binarymoving-window detector.39.52-60 Asaradarantenna scansbyatargetitwillnormally receivenechopulses.Ifmoftheseexpected npulsesexceedapredetermined value(threshold), atargetmaybedeclared tobepresent.Theuseofacriterion thatrequires moutofnecho pulsestobepresent.isaformofintegration. Itislessefficient thanidealpostdetection integration, butithastheadvantage ofsimplicity. Itiscalledthebinarymoving-window detector, butithasalsobeencalleddouble-threshold detector, m-out-of-n detector, coinci­ dencedetector, sliding-window detector, andbinaryintegrator. 
 TO 
 The reference signal  in the noncoherent case is the clutter itself, which will not be as stable as a reference oscillator  because of the finite width of the clutter spectrum caused by its own internal motions. If a  nonlinear IF amplifier is used, it will also limit the improvement factor that can be achieved.  4.10 PULSE DOPPLER RADAR57  ~. 
 8 18-820, November, 1970.  98. Cheston, T. 
 SCAN USING  -(Z CENTER FREQUENCY #OURTESY )%%              
 11.Rihaczek, A.W.:·"Principles ofHigh-Resolution Radar,"McGraw-Hill BookCompany, NewYork, 1969.. EXTRACTION OF INFORMATION AND WAVEFORM DESIGN 439  12. I)clcy, (i. 
 All the generated power in the transmitter  aerials, for example, must go into the main beam, and  not into any of the side-lobes, where it not only would  be wasted, but would cause spurious reflections from  confusing directions. On ships and aircraft the aerials  not only have to be directional for range and height, but  often have to be stabilized to cancel out the motions of  - the ship or aircraft itself. |  . 
 ,lto6rpm ,btenn~aperture, lcnverbcam ..., Sby25ft Antenna aperture, upper be~m, ..... 5by25ft Beamwidth. .................... 
 -- Ê  Ê/,    3IGNAL !NALYSIS AND 4ARGET $ETECTION  4HE OBJECTIVE OF SIGNAL PROCESSING IS TO  DETECT AND CHARACTERIZE ECHOES FROM SCATTERERS OF INTEREST  EITHER DISCRETE AIRCRAFT OR SHIPS  OR EXTENDED THE SEA SURFACE   AND THIS IS CUSTOMARILY ACHIEVED BY DECOMPOS 
 POLARIZED IMAGES THAT ARE SIMILAR TO THOSE THAT HAVE BEEN AVAILABLE FROM MANY AIRBORNE SYSTEMS FOR DECADES  ALTHOUGH NOT AVAILABLE FROM AN 3"2 EXCEPT FOR 3)2 
 Radar System Engineeri ng Chapter 8 – Pulse Radar  51         Figure 8.3  Transmission and receiving spectrum with high PRF.   The detai ls of the respective fundamental principles will be discussed following.   8.3 Simple Pulse Radar   The problem associated with CW Radar devices regarding the de -coupling from transmission  path to reception path is solved by pulse Radar through the temporal separa tion of transmis- sion and reception. 
 3.7).  Although the doppler-frequency spectrum "folds over" in the video because of the  action of the detector, it is possible to determine its sign from a technique borrowed from  single-sideband communications. If the transmitter signal is given by  the echo signal from a moving target will be  E, = k, Eo cos [(too +_ (I),)( + 4) (3.5)  where Eo = amplitude of transmitter signal  k, = a constant determined from the radar equation  oo = angular frequency of transmitter, rad/s  o, = dopper angular frequency shift  #I = a constant phase shift, which depends upon range of initial detection  The sign of the doppler frequency, and therefore the direction of target motion, may be found I by splitting the received signal into two channels as shown in Fig. 
 %23 
 SITE SHORE  MEASUREMENTS SHOWING A SHIFT IN THE SPECTRAL PEAK   AND MEASUREMENTS FROM SHIPS  AT INTERMEDIATE GRAZING ANGLES /THER MEASUREMENTS OF SEA CLUTTER SPECTRA INCLUDE  THOSE MADE AT MUCH LOWER FREQUENCIES IN THE (& BAND  AS DESCRIBED IN THE LAST SECTION THOSE MADE UNDER ARTIFICIAL CONDITIONS IN WAVE TANKS   WHOSE APPLICATION TO REAL 
 14.12). If  OTHER RAlJAR TOPICS55) Chaffwasaveryeffective countermeasure whcnusedwiththerelatively slowbomber aircraftofWorldWarn.Withmodern high-speed aircraft, abundleofchaffquicklyseparates· fromthedispensing aircraftandmakesthejobofdiscriminating betwecn targetandchaff easier.However, chaffneednotbesimplydropped fromthetarget.Jtcanbedispensed from aerialrocketsandfiredahead,behind,above,orbelowthetargetaircraft. Forward-shot chaff candeceive therangeandvelocity tracking gatesoftracking radars. 
 (Frotn Jolt~rsc~rr '" Co~rrtesy Proc. I EEE.) has  TIll'EI.ECTRONICAI.I.Y STEERED PHASED ARRAY ANTENNA INRADAR315 heendemonstrated experimentally. Botharemoresuitedforelectronic scanning inoneangu­ larcoordinate thanfortwo-angle-coordinate electronic scanning. 
 “Bistatic Radars Hold Promise for Future System,” Microwave Systems News , pp. 119–136,  October 1984. 47. 
 Gabriel, W. F. (ed.): Special Issue on Adaptive Antennas, IEEE Trans., vol. 
 B. Sefton, Jr., “An improved design for indoor ranges,” Proc. IEEE , vol. 
      !      # !$   &)'52%   $OPPLER 
 The opposite is generally the case for a pulse doppler radar. Its  pulse repetition frequency is usually high enough to operate with unambiguous doppler (no  blind speeds) but at the expense of range ambiguities. The discussion in this chapter, for the  most part, is based on the MTI radar, but much of what applies to MTI can be extended to  pulse dopplcr radar as well. 
 627–633, 1995.  95. T. 
 L. Pazmany, J. B. 
 Acquisition scenario, top view. 5. Results After a standard range-azimuth data focusing, it was possible to extract the scenario power maps; in Figure 12the resulting SNR map obtained from the SPARX acquisitions is shown. 
 13.3] SELECTIO.V OF THE CATHODE-RAY TUBE 483 readjustment intheweighting ofthesuccessive pulse groups introduced bythis phenomenon isdesirable. Inany case, careful observation has notdetected any appreciable advantage forscreens with very high super- normal buildup. The property ofsupernormal buildup may becon- nected, however, withother desirable ones. 
 11 1. Tatarski, V. I.: " Wave Propagation in a Turbulent Medium." McGraw-Hill Book Co., New York,  1961. 
 the structure; or,iftheelevation angle ofthebeam must beadjustable, theends ofthestructure may besupported byball-bearing trunnions. Surface-based antennas are usually not housed, and therefore are subject towind forces. These forces can bereduced byasmuch as50 per cent ifthe reflector isagrille (Figs. 
  
 As  described in Sec. 10.2, to maximize the output signal-to-noise ratio, the receiver must be  designed as a matched filter, or its equivalent. The matched filter specifies the frequency  response function of the IF part of the radar receiver. 
 arid F. F. Kretschmer, Jr.: Design of a Staggered-prf Moving Target Indication Filter,  T~P Rndio atrd Elc~crrottic Ertgitreer, vol. 
 In practice, the  introduction of IF limiting against the ground clutter returns will result in an additional FIGURE 2.87  Improvement factor comparison of  optimum and adaptive MTI against fixed and moving  clutter of ratio Q FIGURE 2.8 8 Location of the three filter zeros  for an optimum MTI used against  fixed and mov - ing clutter ch02.indd   83 12/20/07   1:46:53 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 928-938, 1946.  3. Wathen, R. 
 THE 
   LOW 
 Morrow: Measurements of Microwave Forward Scattering from  the Ocean al L-Band, IEEE NA ECON '74 Record, pp. 269-274, 1974.  74. 
 Staprans, A., E.W. McCune, and J. A. 
 The result was that the energy inthe transverse mode could bereduced tozero after each group ofthree reflections. Although much engineering remains tobedone, itispossible that delay times can beextended to1000 or‘.2000 psec bythe use of larger blocks. EndCells.—The various ways ofmounting thequartz crystals maybe classified according towhether thebacking behind thecrystal isintended toabsorb ortoreflect. 
 10.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 In an active-switch modulator,  the switch has to be turned off as well as turned on.  Originally, the switch was a vacuum tube and the modulator was called a hard-tube  modulator to distinguish it from the gas-tube switch often used in a line-type modulator.  Since other than vacuum tubes can be used as the switch in an active-switch modulator,  the “hard-tube” designation (meaning a vacuum tube) might not always apply. 
 ch08.indd   1 12/20/07   12:49:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 
 TION 3OME EXAMPLES OF EXISTING SYSTEMS THAT USE  NEAR 
 Graham, R.: The Polarisation Characteristics of Offset Cassegrain Aerials, "Radar -Presi.:nt and  Future," Oct. 23-25, 1973, IEE Cm!{ P11h/. no. 
 96. S. J. 
 Multiple-beam arrayantennas withalargenumber ofsimultaneous beamshavenotseen wideapplication, probably because ofthecomplexity ofsuchsystems. Theyhave,however, hadapplication in3Dmechanically rotating air-surveillance radarswhichemploy asmall number ofcontiguous beamsstacked inelevation toprovide theelevation coordinate. Insomeapplications, theeffectofmultiple, independent beamscanbeobtained witha single-beam phased-array radarwhichiscapable offlexibleandrapidbeamsteering. 
 EARTH 
 For simplicity radio altimeters of this type do not  show minute changes in altitude, but record only in steps  of six feet (on the o—400 feet scale) or 60 feet (on the  400-4000 feet scale). Apparatus of this type has a  reasonable error. In the 50-400 feet sector, for instance,  . 
 The five sections of the antenna are mated and held in position by spring- loaded locks on the ends that are operated by release mechanisms at the end of the deployment cycle. Helical springs are provided on the flange faces along the wide wall for electrically tight joints. Relative leakage power between sections is down by 50 dB. 
 M., and D. Atlas: Precipitation Motion by Pulse Doppler Radar, Proc. Ninth Weather Radar Conf., pp. 
 REGION IRREGULARITIES  USING RANGE  DOPPLER  AND $/! VIA INTERFEROMETRY  MEASUREMENTS   -OTIVATION FOR -22 DEVELOPMENT INCLUDED  LOWER COST  INCREASED SAFETY  SPECTRUM AVAILABILITY  AND PEDAGOGICAL OPPORTUNITY -22 PROVIDES RANGE 
 Toimplement their decision tofollow these suggestions, the Micro- wave Committee oftheNDRC decided tosetupadevelopment labora- tory staffed primarily by physicists from anumber ofuniversities. They were encouraged inthis step bythe success that the British had already experienced with civilian wartime radar development agencies staffed with physicists having nospecial radio experience but good general scientific training. After exploring several possibilities, the. 
 GRID PARABOLOID THAT REFLECTS PARALLEL 
 An additional bistatic caveat is necessary. When the target is on or near the base - line, i.e., located between receiver and transmitter where the bistatic angle b → 180º,  a completely different environment is generated: forward scatter  from both target and  clutter. In this case, the target radar cross section (RCS) and clutter scattering coef - ficient (so) are greatly enhanced, whereas range and doppler measurements are greatly  degraded. 
 TRE assessed the sensitivity of in-service radars and concluded that, forthe 19 aircraft measured, the average sensitivity was 9 dB below optimum and the worst was 18 dB down. Of 13 serviceable transmitters examined, 6 were more than 4 dB down, with the worst 8.5 dB below optimum. The greatest single cause of poorsensitivity was the ‘crystal valve ’(the silicon mixer diode), which on average contributed to a loss of 2.5 dB. 
 21.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 FIGURE 21.13  Typical hyperbolic image of GPR data from a reflector of circular  cross section ( Courtesy IEE ) Xo, ZoX axis Z axis M This equation shows that the measured wavefront appears as a hyperbolic image  or a curve of maximum convexity. Migration technique may be used to move or  migrate a segment of an A-scan time sample to the apex of a curve of maximum  convexity. The hyperbolic curve needs to be well-separated from other features and a  good signal-to-noise ratio is needed for this technique to work well. 
                            . Óx°£ä  2!$!2 (!.$"//+  A GENERAL .#/ WILL BE IN  3ECTION  &OLLOWING THE MULTIPLICATIONS  DIGITAL LOWPASS  FILTERS PREVENT ALIASING WHEN THEIR OUTPUTS ARE DECIMATED BY A FACTOR OF TWO TO PRODUCE  COMPLEX OUTPUT SAMPLES AT A  -(Z RATE )N THE FIGURE  -#303 STANDS FOR  MILLION  COMPLEX SAMPLES PER SECOND 4HE LOWPASS FILTER ALSO REDUCES OUT 
 M. King, “Phenomena of scintillation noise in radar-tracking  systems,” Proc. IRE , vol. 
 Not shown in  Fig. 6.1 arc end-shield disks located at each end of the cathode for the purpose of confining the  electrons to the interaction space.  The straps (7) are metal rings connected to alternate segments of the anode block. 
 85.Taylor,J.W.,Jr.,andG.Brunins: Long-Range Surveillance RadarsforAutomatic Control Systems, RecordoftheIEEE1975International RadarConference, pp.312-317. 86.Mortley, W.S.,andS.N.Radcliffe: PulseCompression andSignalProcessing, International Confer­ enceonRadar-Present andFuture,Oct.23-25,1973,pp.292-296, lEEPublication no.105. 87.Ward,H.R.:Dispersive Constant FalseAlarmRateReceiver, Proc.IEEE,vol.60,pp.735-736, June, 1972. 
 R. Ward, “Doppler processor rejection of ambiguous clutter,” IEEE Transactions on Aerospace  and Electronic Systems,  vol. AES-11, July 1975 and reprinted in D. 
 R.K.:Ground Echo,chap.25of"RadarHandbook," M.I.Skolnik (cd.).McGraw-Hili RookCo..NewYork,1970. 36.Harton, DK.:"Radars. vol.5,RadarClutter," ArtechHouse,Inc..Dedham. 
 € L(n)=10log( 1E(n)) (8.14)  100 10 11 10 100 1000 ^10000n Pfa=Tfa⋅B2F=1012 Pd=0.99 Pd=0.90 Pd=0.50 Pd=0.99 Pd=0.90 Pd=0.50=104 n(operator and CRT)Perfect integratorI(n)- n ⋅E(n) n. number of pulses integrated(postdetection)   Figure 8. 14 Integration factor as a function of the number of the integrated pulses n for  non-coherent integration. 
 26. C.-S. Huang, M. 
 1.)  5. Cutrona, L. J.: Optical Computing Techniques, IEEE Sprctrirm, vol 1, pp. 
 are chosen properly, thebeginning ofthepulse will beflatand thetime forthe pulse tofall to90per cent will begreatly increased. The value ofC, must bechosen tosatisfy therelation C.RP=C.R,. (13) The value ofR,isnot specified, ,but the amount ofdroop becomes less asR,isincreased. 
 60. W. J. 
 54-27. June 15.  1943. 
 115. J. Robey, D. 
 In benign sur- face clutter applications, it is economical to implement the stacked-beam radar without MTI or doppler processing in the beam stack, reserving this processing for a single cosecant-squared receive detection beam. The AN/TPS-43 is an example of a widely deployed operational stacked-beam radar. Deployed in the 1970s, it is a transportable ground-based S-band radar which has been extensively used for air surveillance in the U.S. 
 Olin, I. D., and F. D. 
 754–760, 1991. 34. P. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.576x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 The mismatch loss of this filter is Lm = 1.29 dB, which is well below that of a 105 dB  Dolph-Chebyshev filter bank ( Lm = 3.0 dB). 
 336-348, August 1975. 17. Cutrona, L. 
 FIELD DISTANCE IN INDOOR  FACILITIES BECAUSE MOST CHAMBERS ARE NOT MUCH MORE THAN  FT OR SO IN LENGTH )T IS POSSIBLE  HOWEVER  TO PROVIDE THE NECESSARY UNIFORMITY OF ILLUMINATION BY  COLLIMATING  THE RADIATED BEAM 4HIS CAN BE DONE BY INSERTING A LENS BETWEEN THE RADAR AND THE TAR 
 IIIASV Mk. VIASV Mk. VIASV Mk. 
 28. Finn, H. M., R. 
 Target Height, ft Range, nautical miles (nmi) Lundy Island 800 61 2000 647000 69 Chivenor Buoy 800 20 2000 25 Figure 4.32. Locations of RAF Chivenor, RAF Angle, the Chivenor radar buoy, Grassholm and Lundy Island [ 11].Airborne Maritime Surveillance Radar, Volume 1 4-26. return discriminator. 
 K.: "CW and Doppler Radars," vol. 7, Artech House, Norwood, Mass., 1978, sec. VI-3, pp. 
 17,pp.72-80,May,1978. 56.Hallford, B.R.:LowConversion LossXBandMixer,Microwalle J.,vol.21,pp.53-59,April,1978. 57.Robertson, J.W.,andF.J.Savill:Practical Experience withRearPortDisplays, InterntJtional COI,ler­ enceonDisplaysfor Man-Machine Systems, 4-7April,1977lEE(London) Conference Publication no. 
 7. pp. 63, 65,  April, 1964. 
 PULSE RESPONSE   TO ELIMINATE RANGE ERROR CAUSED BY THE TARGET (OWEVER  VERY STABLE CIRCUITRY IS REQUIRED TO AVOID PULSE JITTER AND DRIFT $OPPLER 3CINTILLATION AND 3PECTRAL ,INES  $OPPLER SCINTILLATION AND SPECTRAL  LINES CAUSED BY A COMPLEX TARGET MAY BE DIVIDED INTO TWO PHENOMENA    SPECTRAL  LINES CAUSED BY PARTS OF THE AIRCRAFT SUCH AS PROPELLERS AND JET TURBINE BLADES  AND   A CONTINUOUS DOPPLER SPECTRUM SPREAD BY THE MOTION OF AN AIRCRAFT IN FLIGHT SYMMETRICALLY  &)'52%     4YPICAL SPECTRAL 
 The echo signal from a particular range interval must compete in a  collapsed-range C-scope display, not only with the noise energy contained within that range  interval, but with the noise energy from all other range intervals at the same elevation arid  azimuth. In some 3D radars (range, azimuth, and elevation) that display the outputs at all  elevations on a single PPI (range, azimuth) display, the collapsing of the 3D radar information  onto a 2D display results in a loss. A collapsing loss can occur when the output of a high-  resolution radar is displayed on a device whose resolution is coarser than that inherent in the  radar. 
 IR  vol. 47. pp. 
 When a solid-state duplexer is used or when a solid-state limiter follows the TR switch,  there need be no initial spike and burnout is not determined by the pulse energy. Burnout due  to pulses without an initial spike, but greater than about 1 ps in duration, is determined  primarily by the peak power.16 (The burnout conditions for pulses 1 ps or greater is essentially  the same as for CW.) Crystal diodes can withstand several watts or more of peak power under  pulse conditions. For pulses shorter than 1 ps, the peak-power capability increases, but not at  a sufficient rate for constant energy. 
 BASED 3!2 INTERFEROMETRY  REVIEWED IN THE FOLLOWING SECTION %XACT 
 Very fast and programmable digital signal- processing chips make it possible for radar meteorologists to have their cake and eat it too. Flexibility due to programmability permits tailoring of the processor's characteristics to the application from day to day or even beam to beam and range gate to range gate. Until recently, most pulse-pair or FFT processors for meteorological radars have been hard-wired and therefore inflexible. 
 SLIGHT VARIES WITH ELEVATION ANGLE 4HIS EFFECT IS  MORE PRONOUNCED AT HIGHER AIRCRAFT SPEEDS AND HIGHER RADAR FREQUENCIES ! CHANGE IN THE MAGNITUDE OF THE CORRECTION FACTOR OR EVEN THE COMPENSATION PATTERN WITH RANGE  HEIGHT  AND VELOCITY COULD BE UTILIZED TO RETAIN PERFORMANCE &IGURE  ILLUSTRATES THE THEORETICAL -4) PERFORMANCE OF A #0#4 SYSTEM AS A  FUNCTION OF BEAM 
 Velocity Search.  VS is a high-PRF search waveform that measures doppler fre - quency unambiguously (with the possible exception of sense), but does not measure  range. This is the classic high-PRF waveform. 
 In order to communi - cate with multiple boards, the serial links from each board go to a high-speed switch  board that connects the appropriate source and destination serial links together to form  a serial fabric.  Examples of popular serial fabric backplanes at this writing include  VXS, VPX, and ATCA. It is apparent that high-speed serial links will be the primary  communication mechanism for multiprocessor machines into the future, with ever- increasing data bandwidths. 
 Theoretically therearenospurious signalsgenerated byinternal reflections ina matched feed.Itisnotalwaysconvenient, however, tousefour-port junctions. Three-port tee junctions aresometimes usedforeconomic reasons toprovide thepowersplitting, hutthe network isnottheoretically matched. Internal reflections duetomismatch inthefeedcan appearasspurious sidelobes intheradiation pattern.so Spacefeeds.Therearetwobasictypesofspacefeedsdepending onwhether theyareanalogous toalensortoareflector. 
 (2), theapplicability of which isnot restricted tothedirection ofmaximum gain ortobeams of any special shape. Once thegain oftheantenna inaparticular direction isspecified, itseffective receiving cross section forplane waves incident jrom that direction isfixed. Equation (2)can bebased rigorously onthe Reciprocity Theorem (see Vol. 
 97.Shrader, W.W.:MTIRadar,"Radar Handbook," M.r.Skolnik (ed.),McGraw-Hill BookCo.,New York,1970,sec.17.20. 98.Shrader, W.W.:Antenna Considerations forSurveillance RadarSystems, SevellthAmlllalEClstCOCJS( Conference onAeronautical andNavigational Electronics, Baltimore, Md.,October, 1960. 99.Ruze,1.:TheElfectofAperture ErrorsontheAntenna Radiation Pattern,SlIppl.alNIIOI'Orimellco. 
 SION TECHNIQUES ARE USED TO REDUCE THE REQUIRED PEAK POWER %VEN SINGLE 'ALLIUM  .ITRIDE DEVICES CAN GENERATE HUNDREDS OF WATTS OF PEAK POWER  AT MEAN POWERS EASILY SUFFICIENT FOR #-2 APPLICATIONS !LSO  ADVANCES IN DIGITALLY CONTROLLED WAVEFORM GENERATORS HAVE GIVEN DESIGNERS THE ABILITY TO CREATE PULSE 
 New insights on AR order selection with information theoretic criteria based on localized estimators. Digit. Signal Process. 
 p Mode of Operation . A magnetron, whether conventional or coaxial, can oscil - late at a number of different, closely spaced frequencies due to various possible con - figurations of the RF field that can exist between the cathode and the resonant cavities.  ch10.indd   14 12/17/07   2:19:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 198-206, Nov., 1967.  I IR. Reed. 
 Figure 8.19 shows the phase modulation characteristic of the Frank Code for the above  example. Note how the phase step between subpulses increases between subpulse  groups with a length equal to four. This characteristic can be regarded as a stepped- phase approximation to quadratic phase modulation. 
 1 3  RF  input LO 90°  hybrid  Junction Diode  mixer  Diode  m,xer 90°  hybrid  junction IF  output  Figure 9.3 Image-recovery mixer. 350 INTRODUCTION TO RADAR SYSTEMS  Diode burnout. A crystal diode which is subjected to excessive RF power may surfer burnout. 
 Slobodnik, A. J., Jr.: Surface Acoustic Waves and SAW Materials, Proc. IEEE, vol. 
 THE 
 TIES OF RANGE MEASUREMENT ! FAN BEAM IS USED TO ILLUMINATE A NARROW STRIP ALONG THE  GROUND  AND THE RANGE RESOLUTION PERMITS SEPARATING THE RETURNS FROM DIFFERENT ANGLES BY THE TIME THEY RETURN 4HIS TECHNIQUE IS ESPECIALLY EFFECTIVE AT ANGLES AWAY FROM THE VERTICAL  FOR THE RESOLUTION NEAR THE VERTICAL IS MUCH POORER THAN NEAR GRAZING )F WE ASSUME THAT  R   IS ESSENTIALLY CONSTANT  THE GAIN IS CONSTANT  THE PULSE IS RECTAN 
 16.Torrey,H.C,andCA.Whitmer: "Crystal Rectifiers," MITRadiation Laboratory Series,vol.15, McGraw-Hili BookCompany, NewYork,1948. 17.Dickens,L.E.,andD.W.Maki:AnIntegrated-Circuit Balanced Mixer,ImageandSumEnhanced. IEEETrans.,vol.MTT-23, pp.276-281, March,1975. 
 Integration over 128 seconds has been found to be suitable, with the  antenna rotating at 120 rpm. The increased capability of (ice) target detection in sea  clutter with higher antenna rotation rates has also been demonstrated. Dramatic images  of ice hazards can be produced by such radars, such as that illustrated in Figure 22.4. 
 Atthereceiving end the video signals and each ofthe subcarriers are separated byappropriate filters and the phase-shifted and the reference sinusoids areobtained by suitable demodulators. The reference wave isthen passed through a phase shifter similar tothat onthescanner. This phase shifter isdriven byaservomechanism whose error signal isthe output ofacircuit which compares the phase ofthe shifted wave and that ofthe reference wave. 
 DELAY CANCELERS 4HE WIDER REJECTION NOTCH ENCOMPASSES MORE OF THE CLUTTER SPECTRUM AND THUS INCREASES THE -4) IMPROVEMENT FACTOR ATTAINABLE WITH A GIVEN CLUTTER SPECTRAL DISTRIBUTION    $ELAY IS USED HERE TO REPRESENT AN INTERPULSE MEMORY FOR AN -4) FILTER !N &)2 FILTER WITH ONE DELAY IS A TWO 
 Where the requirement is for location accuracy, which is primarily a topo - graphic surveying function, the system requirement is less demanding. The plan resolution is defined by the characteristics of the antenna and the sig - nal processing employed. In general radar systems (apart from SAR), to achieve an  acceptable plan resolution requires a high gain antenna. 
 Sensors 2019 ,19, 490 Final LS Estimation It is shown that βiis obtained after L1regularization, and the estimation will be biased towards zeros. Thus, a debiasing step is needed T/prime=supp (ˆsi), (18) siT=(ΦiT/prime)†ri,siT/primeC=0. (19) After the construction of the subaperture images, the generalized likelihood ratio test (GLRT) [ 1] can be implemented for the ﬁnal composite image. 
 TO 
 15.65 15.15 Considerations Applicable to MTI Radar  Systems  ..................................................................  15.69  16. Airborne MTI   ............................................................ 
 AIR 
 L. Wood: Designs for Sidelobe Blanking Systems, Proc. IEEE Int. 
 ARRAYS WITH LOW CALIBRATION EFFORT v  )%%  0ROC  VOL   PT &  NO   PP n  !UGUST   5 .ICKEL  h3UPERRESOLUTION AND JAMMER SUPPRESSION WITH BROADBAND ARRAYS FOR MULTI 
 The antenna gain G is a measure of the power radiated  in a particular direction by a directive antenna to the power which would have been radiatecf  in the same direction by an omnidirectional antenna with 100 percent efficiency. More  precisely, the power gain of an antenna used for transmission is  power radiated per unit solid angle in azimuth O and elevation 4  G(e, 0) = (2.35) power accepted by antenna from its generatorl4n  Note that the antenna gain is a function of direction. If it is greater than unity in some  directions, it must be less than unity in other directions. 
 It is well suited for supporting horn feeds, but it obstructs the aperture.  Two basic limitations to any of the feed configurations mentioned above are aperture  blocking and impedance mismatch in ,the feed. The feed, transmission line, and supporting  structure intercept a portion of the radiated energy and alter the effective antenna pattern. 
 The basis for the linear model82 is a combination of the Skylab results over North America83 and those from Kansas cropland measurements over three com- plete seasons with the microwave active spectrometer (MAS).84 The 13.9-GHz Skylab RADSCAT had a ground footprint of from a 10-km circle at vertical to an ellipse of 20 by 30 km at 50°. The MAS had footprints at 50° ranging from 5.5 by 8.5 m at 1.1 GHz to 1.4 by 2.1 m at 17 GHz, but millions of measurements were averaged for the model. Because the Skylab data was at only one frequency and the responses for the two experiments were essentially the same at thatQUASI-SPECULAR REGION PLATEAU REGION VERTICALPOLARIZATION SHADOW REGION HORIZONTAL POLARIZATION CROSSPOLARIZATIONBACKSCATTERING COEFFICIENT 0° (dB) . 
 IT-10, pp. 152–159, April 1964. 21. 
 MENT v )%%% 4RANS !NT 0ROP  VOL !0 
 Leung et al.38   © IEEE 1999 ) ch07.indd   22 12/17/07   2:13:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 The parabolic cylinder antenna can be  applied to achieve a precisely shaped beam  from a common aperture. The AN/TPS-63  (Figure 12.18) uses a vertical array to pro - vide fine control of the elevation pattern  with a single elevation column feed array  and so is very cost effective. The eleva - tion beam-shaping incorporates a steep  beam slope at the horizon to allow radar  operation at low elevation angles without  degradation from ground reflections. 
  
 14. Huang, Z.; Tan, W.; Huang, P .; Sun, J.; Qi, Y.; Wang, Y. Imaging algorithm study on ARC antenna array ground-based SAR. 
 PLUS 
 ch06.indd   46 12/17/07   2:04:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 The GNSS can map the TEC of the ionosphere globally and in real-time, but the spatial resolution of the observation is too Sensors 2019 ,19, 516; doi:10.3390/s19030516 www.mdpi.com/journal/sensors 201. Sensors 2019 ,19, 516 low for the ﬁne analysis of ionosphere above a certain area [ 10]. Recently, full polarimetric spaceborne synthetic aperture radar (PolSAR) was demonstrated to be qualiﬁed for ionospheric inhomogeneities imaging [ 11]. 
 A. Bourdillon, J. Delloue, and J. 
 Subsequent stages of the receiver  and signal processor have responses that are functions of the doppler modulation fre - quency, so the output spectrum can be obtained by combining the responses of these  filters with the spectrum present at the mixer input. In MTI systems, it is common to  describe the ability to suppress clutter in terms of an MTI improvement factor. The  MTI improvement factor I is defined as the signal-to-clutter ratio at the output of  the clutter filter divided by the signal-to-clutter ratio at the input of the clutter filter,  averaged uniformly over all target radial velocities of interest. 
 The loss and weight penalty (WlA = 4.02 kg/m2) of a corporate-feed network is compensated for by using transmit and receive gain at each of 384 subpanels. U.S.S.R. Cosmos 1500 Antenna. 
 Nelson, T. M., and H. Goldie: Fast Acting X-Band Receiver Protector Using Varactors, /EEE M7T  Symposium Digest, pp. 
 AnADTsystem performs thefunctions oftargetdetection, trackinitiation, trackassociation, trackupdate, tracksmoothing (filtering) andtracktermination. Thea/ltomatic detector partoftheADTquantizes therangeintointervals equaltothe rangeresolution. I\teachrangeintervalthedetector integrates npulses,wherenisthenumber. 
 One type of storage device that has been used in scan converters is a double-ended  storage tube with two electron guns, one on each side of a charge-storage surface.32 The  radar output is written in PPI format by one electron gun on one side of the charge-storage  surface. The second gun, on the other side of the storage surface, reads the stored charge  pattern with a TV raster. The video outputs of several different radars, each with their own  scan converter, can be combined on a single TV display. 
 • The collapsing loss for the linear detector can be several decibels greater than the loss for a square-law detector5 (see Fig. 8.1). The collapsing loss is the ad- ditional signal required to maintain the same P0 and Pfa when unwanted noise samples along with the desired signal-plus-noise samples are integrated. 
 angle. Both the B-scope and the PPI, being  intensity modulated, have limited dynamic range. Another form of display is the A-scope,  shown in Fig. 
 TION LOGIC OF THESE THRESHOLDS IS ALSO SHOWN IN &IGURE  4HE BLANKING THAT OCCURS BECAUSE OF THE MAINGUARD COMPARISON AFFECTS THE  DETECTABILITY IN THE MAIN CHANNEL  THE EXTENT OF WHICH IS A FUNCTION OF THE THRESH 
 BEAM CLUTTER 4HIS BLANKED REGION IN DOPPLER IS KNOWN AS THE MAIN 
 J. Walsh, and J. L. 
 At10°Cand10cmwavelength, itis. 500 INTRODUCTION TO RADAR SYSTEMS  approximately 0.93. Its value for ice at all temperatures is about 0.197 and is independent of  frequency in the centimeter-wavelength region. 
 J ., pp. 623–650, May–June 1968. 72. 
 35–349, 1961. 43. W. 
 Barnum and E. E. Simpson, “Over-the-horizon radar target registration improvement by  terrain feature localization,” Radio Science , vol. 
 1977.  70. Ament, W. 
 for example, the target is approaching the radar, the beat frequency  J;,(up) produced during the increasing, or up, portion of the FM cycle will be the difference  between the beat frequency due to the range fr and the doppler frequency shirtf4 [Eq. (3.12a }].  Similarly, on the decreasing portion, the beat frequency !,,(down) is the sum of the two  [ Eq. 
 BAND EXTENDED INTERACTION KLYSTRON FOR  THE #LOUD3AT PROGRAM v )%%% 4RANSACTIONS ON %LECTRON $EVICES  VOL   PP n    9 3ENBOKUVA  3 3ATOH  + &URUKAWA  - +OIIMA  ( (ANADO  . 4AKAHASHI  4 )QUCHI  AND  + .AKAMURA  h$EVELOPMENT OF THE SPACEBORNE DUAL 
 Duty cycle =  0.0009, peak current = 24 A. pulse width =  2.25 ps, frequency = 5.65 (illz. (C'orrrlcsy  Varian Associates, l,tc., Beverly, M.4.)  198INTRODUCTION TORADAR SYSTEMS Thestanding-wave patternalongatransmission linerepeatsitselfeveryhalfwavelength; therefore, 360°inthediagram istakenasa.half wavelength. 
 TORTION IS TYPICALLY CAUSED BY FILTERS AND TRANSMISSION LINE REFLECTIONS 4IME DOMAIN AMPLITUDE AND PHASE DISTORTION  TERMED  MODULATION DISTORTION BY #OOK AND "ERNFELD   CAN RESULT FROM POWER SUPPLY RIPPLE IN HIGH 
 N. Sullivan, and A. S. 
 TO 
 A. Senior, “Studies of scattering by cellular plastic materials,” University of  Michigan, Rad. Lab. 
 TheGermans deployed severaldifferent typesofradarsduringWorldWarII.Ground­ basedradarswereavt,lilable forairsearchandheightfindingsoastoperform groundcontrol ofintercept (GCI).Coastal, shipboard, andairborne radarwerealsoemployed successfully in significant numbers. Anexcellent description oftheelectronic battleinWorldWar11between theGermans andtheAllies,withmanylessonstooffer,isthebook"Instrllmetlts ojDarkness" byPrice.13 TheFrencheffortsinradar,although theygotanearlystart,werenotasenergetically supported asinBritainortheUnitedStates,andwereseverely disrupted bytheGerman occupation in1940.12Thedevelopment ofradarinItalyalsostartedearly,butwasslow.There wereonlyrelatively fewItalian-produced radarsoperationally deployed bythetimetheyleft thewarinSeptember, 1943.TheworkinJapanwasalsoslowbutreceived impetus from disclosures bytheirGerman alliesin1940andfromthecaptureofUnitedStatespulseradars inthePhilippines earlyin1942.Thedevelopment ofradarintheSovietUnionwasquite similartotheexperience elsewhere: Bythesummerof1941theyhaddeployed operationally a number of80-MHz air-search radarsforthedefense'ofMoscow againsttheGerman invasion.14Theirindigenous effortswereinterrupted bythecourseofthewar. Thus,radardeveloped independently andsimultaneously inseveralcountries justpriorto WorldWarII.Itisnotpossible'to singleoutanyoneindividual astheinventor; therewere manyfathersofradar.Thiswasbroughtaboutnotonlybythespreadofradiotechnology to many coun~ries, butbythematuring oftheairplane duringthissametimeandthecommon recognition ofitsmilitarythreatandtheneedtodefendagainstit. 
 ” detecting targets inthat direction iswasteful. Itwould bemost desirable toadjus~the-directional pattern oftheantenna sothat just the desired angular coverage, and nomore, would beobtained. Aprescription for such anantenna pattern can beobtained from thebasic radar equation, Eq. 
 having its own effective input noise temperature Te, representing its intrinsic available output noise power referred to its own input terminals. Here intrinsic means the power that the transducer would generate with a noise-free input ter- mination of the same impedance as the actual input termination. Transducer out- put power is referred to the input terminals by dividing the output power by the available gain of the transducer. 
 53. A. S. 
 7.1.Wheeler, H.A.:ASurveyoftheSimulator Technique forDesigning aRadiating Element ina Phased-Array Antenna, ..PhasedArrayAntennas, Proceedings ofthe1970PhasedArrayAntenna Symposium," ArtechHouse,Inc.,Dedham, Massachusetts, 1972,pr.13214X. 74.Carter,P.S.,Jr.:MutualImpedance EffectsinLargeBeamScanning Arrays,IRETrans.,vol.AP-ll, pp.276-285. May,1960. 
 Experimental results areshownRaindrop Quarter-wave plate inFig. 3.14. Theaverage intensity ofthe rain echo atagiven range was reduced approximately 26db, while theground targets (buildings) JW’ which were being observed attheKA”tenna ~same time suffered areduction of 4to8db. 
 OF 
 /1, 
 Swerling6 calculated the standard  deviation of the optimal estimate by using the Cramer-Rao lower bound. The results  LINEAR DETECT ORN = 1 SQU ARE-LA W DETECT ORN = 8 N = 64 N = N = 64 N = 8 N = 1 10246810COLLAPSING LOSS (dB)1214161820 2 4 6 10 20 40 6 0 100 COLLAPSING RA TIO r200 8 FIGURE 7.1  Collapsing loss versus collapsing ratio for a probability of false alarm of 10−6 and a prob - ability of detection of 0.5 ( after G. V . 
 A number of SBR SAR missions have been considered by various countries for various purposes. An example is the Canadian Radarsat, which employs a C- band SBR SAR primarily for monitoring polar ice dynamics for use in ship rout- ing; the SAR will have a 200-km swath. In planetary exploration areas, SBR imaging systems are key elements for the ex- ploration of two bodies that are continuously cloud-covered, Venus and Titan. 
   ")34!4)# 2!$!2   ÓÎ°£x 4HE TERM  F" ALSO DEFINES THE  DOPPLER BEAT FREQUENCY   WHICH IS PRODUCED BY MIX 
 Abroadband ATR tube isused primarily topass beacon signals with minimum loss, and awider i-fband than necessary foroptimal signal-to-. 624 EXAMPLES OFRADAR SYSTEM DESIGN [SEC. 1514 netweight ofthecomponents isabout 120lb. 
 3, pp. 397–401, July 1988. 101. 
 TIONS AND THAT THE TECHNIQUE  THROUGH THE EASIER REALIZATION OF DIRECTIONAL SOURCES  HAD ADVANTAGES OVER SEISMIC METHODS 0ULSED TECHNIQUES WERE DEVELOPED FROM THE S ONWARD AS A MEANS OF PROBING TO CONSIDERABLE DEPTHS IN ICE 3TEENSON  AND %VANS   IN FRESH WATER AND SALT DEPOSITS 5NTERBERGER  IN DESERT SAND AND ROCK FORMATIONS  +ADABA AND -OREY  0ROBING OF ROCK AND COAL WAS ALSO INVESTIGATED BY #OOK  AS  WELL AS 2OE  ALTHOUGH THE HIGHER ATTENUATION IN THE LATTER MATERIAL MEANT THAT DEPTHS  GREATER THAN A FEW METERS WERE IMPRACTICAL .ILSSON GIVES A MORE EXTENDED ACCOUNT  OF THE HISTORY OF '02 AND ITS GROWTH UP TO THE MID 
 Rotation of the heams causes the plane of polarization to rotate which can  cause undesirahlc target amplitude lluctuations at the scan rate. Although such fluctuations  are theoretically removed by the monopulse type of processing, in practice the removal is not  complete and angular error can result.R6 With modern solid-stale technology, the need for a  third receiver in the conventional monopulse tra.cker might not be as difficult-to realize in  praclic<: as t lie complexity of properly scanning a pair of squinted beams. Generally it can he  said that tile amplitude-comparison n1011opulse tracking system is usually preferred over this  hybrid technique. 
 ELS FOR DESCRIBING LAND AND WATER RADAR RETURN PHENOMENA v 0H$ DISSERTATION  5NIVERSITY OF .EW  -EXICO  !LBUQUERQUE    & * *ANZA  2 + -OORE  AND 2 % 7EST  h!CCURATE RADAR ATTENUATION MEASUREMENTS ACHIEVED BY  INFLIGHT CALIBRATION v )%%% 4RANS  VOL 0') 
 Largebandwidth meansthathighrange-resolution canbeachieved. Italso reduces thelikelihood ofmutualinterference between equipments, andmakesmoredifficult 30 I300 IFrequency'" GHz 3,000 3 x104 I I ,...Millimeter -+-Submillimeler--+t+---Far infrared'+ ··Infrared· ~I 60GHz02 resonance ~94GHZbandwintdow 1.0cm 10mm 01mm WavelengthC02 laser 11 10JimVisible 10Jim Figure14.14Theelectromagnetic spectrum offrequencies abovethemicrowave region.. OTHER RADAR TOPICS 561  the emective application of electronic countermeasures. 
 (9.4)]. The first network is the mixer with noise figure t, Le and  gain = 1/ Le. The second network is the IF amplifier with a noise figure F1F. 
 21.2 Eq. (21.8) was derived for a radar in strip- map mode, i.e., for the case that the radar antenna is in a fixed orientation and the radar beamwidth RK/D is used as the length of synthetic aperture generated. One can increase the antenna length by use of spotlight mode. 
 frequency and power were quite approximate. Maintenance was dif ﬁcult and harmonics from the transmitter interfered with the communication receiver, which prevented the keeping of a continual listening watch when on patrol. 2.2 ASV Mk. 
 Sensors 2019 ,19, 490 T able 2. Time taken (in minutes) by the three algorithms. CS Debiased-CS LS-CS-Residual 154.94 162.69 139.45 5. 
 D. Steinberg, Principles of Aperture and Array System Design—Including Random and  Adaptive Arrays , New York: John Wiley & Sons, 1976.  5. 
 Spatially adap - tive processing (SAP) reduces this problem by adjusting the amplitude and phase of  the sampled receiver outputs in such a way as to minimize the integrated noise power  leakage, while preserving the gain/sensitivity of the beam being synthesized. Figure 20.23 compares conventional processing and SAP applied to the same block  of radar data. A reduction of some 20 dB is achieved in this example, where noise,  not clutter, is the problem. 
    &)'52%   3URFACE ROUGHNESS  DK  VS LOSS &)'52%   3YSTEMATIC DIS 
 SHAPED CLUTTER SPECTRUM .   -4) 2!$!2  Ó°Î£ PROCESSOR DESIGNS AS DISCUSSED IN 3ECTION  .OTE THAT FOR  RF4 y  THE AVERAGE 3#2  IMPROVEMENT IS DUE ONLY TO THE COHERENT INTEGRATION OF ALL THE PULSES IN THE #0) !N -4) FILTER CAN ALSO BE DESIGNED BASED ON THE CRITERION OF MAXIMIZING THE SIGNAL 
 NOISE RATIO FOR VARI 
 Orosei, O. Bombaci, F. Provvedi, and E. 
 As the radar signals traverse the ionosphere, motions of the  plasma medium along the propagation path imprint themselves on the signals in ways  that can degrade or obliterate the target information of interest. Skywave radars can be  designed to recognize the signatures of these phenomena, adjusting the radar frequency,  choice of waveform, and processing to mitigate their effects where necessary. Sometimes  the ionospheric motions actually help the radar, for example, by enabling it to discrimi - nate between natural noise and some forms of deliberate interference. 
 The synthetic aperture radar may be considered as a vector summa-  tion of synthetic-array elements (which is the model generally taken in this section), or it may  be considered in terms of doppler filtering. In fact, it was originally conceived by Carl Wiley of  Goodyear Aircraft Corporation in 1951 as a doppler-filtering process rather than as a syn-  thetic antenna. The two models are sometimes used interchangeably, depending upon which  describes more clearly a particular effect. 
 69. P. M. 
 TION OF TARGET RANGE AND DOPPLER RETURNS IN A SPARSE TARGET SPACE    2ANGE BLIND  ZONES ARE THOSE RANGES IN WHICH A TARGET IS ECLIPSED BY THE TRANSMITTED PULSE 6ELOCITY OR DOPPLER BLIND ZONES ARE THOSE VELOCITIES OR DOPPLERS THAT ARE EXCLUDED DUE TO THE &)'52%  4YPICAL -&!2 TIMING SEQUENCES   #OURTESY 3CI4ECH 0UBLISHING  .   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°£Ç MAIN 
 Rotondo, A. M. Andrews, and AE. 
 It is more meaningful, however, to describe and  depict the processing in an analog manner. ‡  The IF bandpass limiter [ Radar Handbook, 2 nd Ed., pp. 3.30–3.32] shown in this and subsequent diagrams has an  amplitude output characteristic that is linear for input signal voltages from noise level to within 6 dB of the limiter  output maximum voltage and  then transitions smoothly to the maximum output voltage.32 The phase of the input  signal is precisely preserved. 
 AES-4 pp. 168-174, November, 1968.  54. 
 DYNAMIC RANGE ANALOG 
 EVER  THESE DEFINITIONS HAVE BECOME LESS COMMON DUE TO THE EXTENSIVE USE OF DIGITAL SIGNAL 
 SHAPED SPECTRUM WITH A NORMALIZED WIDTH  OF RF4    IS SHOWN IN &IGURE  )N THIS CASE  A COHERENT PROCESSING INTERVAL OF   #0)   NINE PULSES WAS ASSUMED  AND THE LIMITATION DUE TO THERMAL NOISE WAS IGNORED  BY SETTING THE CLUTTER LEVEL AT  D" ABOVE NOISE )T SHOULD BE KEPT IN MIND THAT %Q  FOR THE OPTIMUM WEIGHTS WILL YIELD A DIF 
   B    
 56 transmitter, and thedoppler frequency. The d-ccomponent isremoved bypassage through atransformer, orotherwise, and thedoppler frequency isused toactuate theindicator. Anincidental but important advantage ofthis modification isthat itenables the useofasuitable and easily adjustable crystal current. 
 1975.  29. Hyltin. 
 For MRWS detections,  another MRWS dwell is used for Track Acquisition. Once the track file is initiated, several  rapid track updates are used to firmly establish the track. When doing Single-Target Track updates, a single PRF waveform can be used. 
  
 Theechofromamovingtargetproduces afrequency shiftduetothedopplereffect,which isameasure oftherelativeuelocity. Relative velocity alsocanbedetermined f,omtherateof changeofrange.Tracking radarsoftenmeasure relativevelocity inthismannerratherthanuse thedoppler shift.However, radarsforthesurveillance andtracking ofextraterrestrial targets, suchassatellites andspacecraft, mightemploy thedoppler shirttomeasure directly the relativevelocity, butitisseldomusedforthispurpose inaircraft-surveillance radars.Instead, aircraft-surveillance radarsusethedoppler frequency shifttoseparate thedesiredmoving targetsfromtheundesired fixedclutterechoes,asinMTIradars. Hthetargetcanbeviewedfrommanydirections, itsshapecanhedetermined. 
 (Co~trrcsy l?i' ~Y~~sritlyhotrsr. Itic.)  Table 14.1 Characteristics of two air traffic control radars28.46.56  Frequency band  Freq i~ency  Instrt~mented range  Peak power  Average power  Noise figure  Pulse width  Pulse repetition frequency  Antcnna rotation rate  Ante~tna size  Azimuth beamwidth  Elevation coverage  Antenna gain  Polarization  Blind speed  MTI improvement factor L  1250-1350 MHz  200 nmi (370 km)  5 MW  3.6 kW  4 dB  2 11s  310-365 HZ  5 rpm  12.8 m by 6.9 m  1.25"  40"  34 dB  hor, vert, or circular  1200 knots  39 dB S  2700-2900 MHz  60 nmi (1 I1 km)  1.4 MW  875 W  4 dB  0.6 jts  700- 1200 HZ  1040 Hz (ave)  12.8 rpm  4.9 m by 2.7 m  1.35"  30"  33 dB  vert or circular  800 knots  34 dB  538INTRODUCTION TORADAR SYSTEMS ,. "·'.'I;"~'~\",,~,:\,>"~~ '.-i.. 
 RADAR RECEIVERS  6.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 The receiver front end may also include a limiter, used to protect the receiver cir - cuitry from damage due to high power that may occur either from leakage during  transmit mode or as a result of interference from another system such as a radar at close  range. Front-end limiters are discussed in more detail in Section 6.8. The radar or receiver front end often includes some form of gain or attenuation con - trol as shown in Figure 6.1. 
 Carroll: "Improved Sweep Waveform Generator for Bistatic Radar," U.S. Naval Postgraduate School, Monterey, Calif., August 1975. 84. 
 In the past, some  long-range Air Traffic Control Air Route Surveillance Radars used a magnetron, but  the klystron seems to be the preferred choice for this application. Crossed-Field Amplifier . Although these tubes were employed for some major  radar applications because they have good efficiency, require relatively low voltage,  and have wide bandwidth (about 10%), they are less likely to be used because they are  noisy (which affects their doppler-processing performance), they are of relatively low  gain (which requires the transmitter to have multiple stages), and because the klystron  is usually a better overall choice. 
 In the United States, this was an azimuth  scanning S-band fire control radar, the Mark 8, that was widely used on cruisers and   battleship^,^ and the AN/APQ-7 (~agle) high-resolution navigation and bombing radar at  X band that scanned a 0.5" fan beam over a 60" sector in 14  second^.^ The British used the  phased array in two height-finder radars, one at VHF and the other at S band.6 The Germans  employed VHF radars with fixed planar phased arrays in significant numbers.' One of these,  CHAPTER EIGHT THEELECTRONICALLY STEERED PHASED ARRAY ANTENNA INRADAR ,. 8.1INTRODUCTION Thephasedarrayisadirective antenna madeupofindividual radiating antennas, orelements. whichgenerate aradiation patternwhoseshapeanddirection isdetermined bytherelativ~ phasesandamplitudes ofthecurrents attheindividual elements. 
 The voltage can bealtered tocompensate fortemperature changes bymanual adjustment ofthespeed governor ontheengine. Work has been initiated onthe development ofsmall prime movers other than conventional gasoline engines. Small steam engines that were capable ofabout 300 mechanical watts output were built byRadia- tion Laboratory, but nosatisfactory boiler had been developed atthe close ofactivity. 
 9.13 theguide width (and thereby thewavelength intheguide)’ periodically; this, inturn, varies the effective dipole phasing and moves the beam in azimuth. FIu.fl.18.-AN/.4P7-7 antenna housing onaB-24. Ifallthedipoles areexcited inthesame phase, thebeam isbroadside tothearray and directed straight ahead oftheaircraft. 
 Other errors might be introduced in the CW radar if there are uncontrolled variations in  the transmitter frequency, modulation frequency, or frequency excursion. Target motion can  cause an error in range equal to v, To, where v, is the relative velocity and To is the observation  time. A,t short ranges the residual path error can also result in a significant error unless  compensated for. 
 T.: Design of Line-Source Antennas for Narrow Beamwidth and Low Sidelobes, IRE Trans., vol. AP-3, pp. 16-28, January 1955. 
  n E E n n n n E 
 NAL PROCESSING EMPLOYED )N GENERAL RADAR SYSTEMS APART FROM 3!2   TO ACHIEVE AN  ACCEPTABLE PLAN RESOLUTION REQUIRES A HIGH GAIN ANTENNA 4HIS NECESSITATES A SUFFICIENTLY LARGE APERTURE AT THE LOWEST FREQUENCY TO BE TRANSMITTED 4O ACHIEVE SMALL ANTENNA DIMENSIONS AND HIGH GAIN  THEREFORE  REQUIRES THE USE OF A HIGH CARRIER FREQUENCY  WHICH MAY NOT PENETRATE THE MATERIAL TO SUFFICIENT DEPTH 7HEN SELECTING EQUIPMENT FOR A PARTICULAR APPLICATION  IT IS NECESSARY TO COMPROMISE BETWEEN PLAN RESOLUTION  SIZE OF ANTENNA  THE SCOPE FOR SIGNAL PROCESSING  AND THE ABILITY TO PENETRATE THE MATERIAL 0LAN RESOLUTION IMPROVES AS ATTENUATION INCREASES  PROVIDED THAT THERE IS SUFFICIENT SIG 
 DOPPLER COUPLING OF THE ,&- WAVEFORM  THE APPARENT  TIME DELAY OF THIS TARGET WILL BE   SAPP    
 The slash through the output of the ADC with a “16” above it in Figure 25.9 indi - cates that our ADC produces 16 bits of digital output. ADCs provide approximately  6 dB of dynamic range per bit, so our 16-bit ADC provides about 96 dB of dynamic  range, assuming ADC nonlinearities are negligible. A General Approach to Digital Downconversion. 
 Phase-shift Unit. —Figure 16.28 shows, inmore detail than thesimpli- fied diagram ofFig. 16.25b, the arrangement ofthe phase-shift unit required forMTI onamoving system. 
 The ray path is bent to the Earth.  A correction factor k is used in  the calculation of the rang e of coverage.  € Rphys=Rgeom k=2kRE(hT+h0) (3.14)  For a linear running refractive index profile, k follows as:  € k=1 1+RE⋅dn dh (3.15)  Here  € dndh indicates the differential change of the refractive index n with height/altitude h. 
 (ILL "OOK #OMPANY    P   'LOSSARY OF -ETEOROLOGY  ND %D  "OSTON !-3    P   $ !TLAS AND % +ESSLER )))  h! MODEL ATMOSPHERE FOR WIDESPREAD PRECIPITATION v  !ERONAUT %NG  2EV  VOL   PP n    - +ERKER  - 0 ,ANGLEBEN  AND + , 3 'UNN  h3CATTERING OF MICROWAVES BY A MELTING SPHERICAL  ICE PARTICLE v * -ETEOROL  VOL   P     ! # "EST  0HYSICS IN -ETEOROLOGY  ,ONDON 3IR )SAAC 0ITMAN  3ONS  ,TD    * ! 3AXTON AND ( ' (OPKINS  h3OME ADVERSE INFLUENCES OF METEOROLOGICAL FACTORS ON MARINE  NAVIGATIONAL RADAR v 0ROC )%% ,ONDON   VOL   PT )))  P     * . #HRISMAN AND # ! 2AY  h! FIRST LOOK AT THE OPERATIONAL DATA QUALITY  IMPROVEMENTS PROVIDED  BY THE /PEN 2ADAR $ATA !CQUISITION /2$!  SYSTEM v IN  ST )NT #ONF ON )NFOR 0ROCESSING 3YS  ))03  FOR -ETEOROL  /CEANOG  AND (YDROL  3AN $IEGO  #!  02    - 3ACHIDANANDA AND $ 3 :RNIC  h#LUTTER FILTERING AND SPECTRAL MOMENT ESTIMATION FOR DOP 
 The pulse length is1psec and therepetition rate is39o pps. Since thepeak voltage atthecathode isabout 28kv,good clearance must bemaintained. The magnetron output isin1~-in. 
 Cohen, “Time-frequency distributions–a review,” Proceedings of the IEEE , vol. 77, no. 7,   July 1989. 
 TARGET TRACK DATA v  )%%% 4RANS   VOL !%3 
 Appl. Remote Sens. 2016 ,10, 10–14. 
 3.4 and 3.5). Figure 3.6 shows an example of the measured modulation spectrum of a stalo (curve 1) and the effect of 15-|jis delay on the clutter residue (curve 2). A com- puter program can be utilized to alter the measured spectral data, using the filters of Fig. 
 Barton and W. W. Shrader, “Interclutter visibility in MTI systems,” in IEEE EASCON ’69  Tech. 
 In a lossless medium, all the energy entering the tube at one end must come out the other, but energy losses within the medium may also be accounted for. An incident wave may be rep- resented as a collection of a large number of rays, and when a ray strikes a sur- face, part of the energy is reflected and part is transmitted across the surface, The amplitude and phase of the reflected and transmitted rays depend on the proper- ties of the media on either side of the surface. The reflection is perfect if the sur- face is perfectly conducting, and no energy is transmitted across the boundary. 
 Given the applicable small  range-velocity product (Table 18.1), the antenna area needs to be only ∼ 1 m2 to satisfy  the minimum area constraint (Eq. 18.4). These radars are indeed low mass, at about 8 kg  and 12 kg, respectively, including in each case their antenna. 
 BLOWN MOTION 4HERE ARE OCCASIONAL CLUTTER RESIDUE SPIKES WHEN CLUTTER EXCEEDS THE LIMIT LEVEL  AND IN THE PAST  THE ENERGY FROM THESE SPIKES OF RESIDUE HAS BEEN SUPPRESSED BY FURTHER REDUCTION OF THE LIMIT LEVEL 7HEN LIMITERS HAVE BEEN USED TO NORMALIZE THE ENERGY OF CLUTTER RESIDUE SPIKES  THE AVERAGE IMPROVEMENT FACTOR OF THE -4) SYSTEMS DRASTICALLY DETERIORATES 4HE EQUA 
 Inthewartime systems which provided means ofprecise navigation byaccurate measure- ment cfthe ranges totwo ground beacons atknown positions, special indicators were used. They displayed and measured thepositions ofthe steady beacon signals obtained byusing omnidirectional antennas rather than scanners. There isanupper limit onthefrequency towhich itisdesirable togo. 
 Any departure from this condition will result incir- culating currents inthe stators which will cause amotor action tending toproduce alignment. Ifone rotor isdriven, the other will follow, with only enough lagtofurnish thenecessary power. Ifthesecond rotor has little ornomechanical load, this lagwill bevery small atrotational speeds uptoafew revolutions persecond; iftheload isappreciable, thelagmay amount toafew degrees. 
 This rather clumsy expedient, although itisactually feasible, would scarcely bejustified solely asa means ofavoiding areduction inpulse-repetition frequency. Itismen- tioned only toshow that objectionable second time around, oreven “nth time around, ”echoes could beeliminated ifnecessary without reduction inPRF and without adrastic change intheradar process.. 118 LIMITATIONS OF PULSE RADAR [SEC. 
 In the case of linear FM with large pulse-  compression ratio, the amplitude weighting applied to the time waveform is of the same form  as the weighting applied to the frequency spectrum, for the same output respo~se.~'  Amplitude-modulating the transmitted signal is not usually practical in high-power radar  Table 1 1.1 Properties of weighting functions  Peak Mainlobe Sidelobe  sidelobe Loss width decay  Weighting function dB dB (relative) function  Uniform - 13.2 0 1 .O I If  0.33 + 0.66 cosZ (nflB) - 25.7 0.55 1.23 111  cos2 (nf/B) -31.7 1.76 1.65 111'  Taylor (ii = 8) -40 1.14 1.4 1 I lt  Dolph-Chebyshev -40 ..... 1.35 I  0.08 + 0.92 cos2 (7EflB) (Hamming) -42.8 1.34 1.50 I/[  R = bandwidth  426INTRODUCTION TORADAR SYSTEMS smallsize,andhighlyreproducible inmanufacture. Theamplitude weighting toreduce sidelobes canbeintegrated directly intotheinterdigital transducer design.Inaddition tothe linearFM,theycanbedesigned tooperatewithnonlinear frequency modulations, phase-coded pulses,andtheburstpulse. 
 2.4. Ground Displacement Monitoring The following seven papers are speciﬁcally dedicated to applications. The ﬁrst two [ 13,14] use SAR interferometry (InSAR) for investigating displacements related to land subsidence and highway deformation. 
 IIIC. A block diagram of ASV Mk. VIC is shown in ﬁgure 4.24 [6]. 
 64,   pp. 581–594, May 1976.  8. 
 The TR in  the fired condition acts as a short circuit to prevent transmitter power from entering the  receiver. Since the TR is located a quarter wavelength from the main transmission line, it  appears as a short circuit at the receiver but as an open circuit at the transmission line so that  it does not impede the flow of transmitter power. Since the A TR is displaced a quarter  wavelength from the main transmission line, the short circuit it produces during the fired  condition appears as an open circuit on the transmission line and thus has no effect on  transmission. 
 resulk: from. the' inverse, frequency dependence of flicker noise.  Figure 3.4 shows a bl&k.diagrarh.of thc*EW radar whose receiver operates with a nonzero IF. 
 A target in the main  beam at range, Rt, and velocity, Vt, may have to be observed in the presence of both  range and doppler ambiguities. Only the target’s line-of-sight velocity, Vtlos, is observ - able on a short term basis. The radar designers’ problem is to select the best waveform  in this target-clutter geometry. 
 3HALOM  h"ENCHMARK FOR RADAR ALLOCATION  AND TRACKING IN %#- v )%%% 4RANS  VOL !%3n  NO  PPn    4 +IRUBARAJAN  9 "AR 
 26. Y . Wu, M. 
 [ CrossRef ] 10. Zhu, J.; Li, Z.; Hu, J. Research progress and methods of InSAR for deformation monitoring. 
 Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). 262. 
 31, no. 3, pp. 928–950, July 1995. 
 1  Figure 8.25 Si~nultaneous postan~plifier heani formation. 4, = constant phase; I$, - $,I = IA+l =  1 ?rr(d/;.) sin O0 1.  convenient rnetliod fvr obtaining multiple beams at IF. 
 In principle, a conventional secondary radar solution could have been adopted but  international consensus favored the SOTDMA approach, as it was capable of provid - ing higher levels of data exchange, particularly to aid VTS and security activities. An  important advantage of the chosen AIS solution is its radio frequency. It is sufficiently  low so that reasonable communications are maintained in situations where there is no  visual or radar line-of-sight. 
 For one thing the operator cannot, except onthe fastest sweeps, realize the fundamental range resolution without optical aids even ifthe display were tomake itavailable; indeed, ona5-in. tube the spot-size resolution fora100-mile sweep isnearly asgood ascan be comfortable yused, altbough ona12-in. tube itisthree orfour times worse. 
 With the immediate need for carrier-borne air cover and with the Barracuda not yet in production, an ASV installation wasplanned for the Sword ﬁsh, for use on small escort carriers. The ASV for the Sword ﬁsh was known as ASV Mk. XI. 
 BASED DUCT AND IS ILLUSTRATED IN &IGURE  .OTE THE  DUCT  IDENTIFIED BY THE DASHED LINE  CONTAINS THE TRAPPING LAYER AND hNORMALv GRADIENT LAYER BELOW 4HE THIRD TYPE OF SURFACE DUCT IS ONE CREATED BY A RAPID DECREASE OF RELATIVE HUMIDITY IMMEDIATELY ADJACENT TO THE AIR 
 0-scope. An A-scope modified by the inclusion of an adjustable notch for measuring distance.  PPI, or Plan Position Indicator (also called P-scope). 
 One member of each pair is due to the total surface current on the diffracting edge (including the assumed filamentary edge currents), and the other is due to the uniform physical optics currents. Mitzner subtracted one member of each pair from the other, thereby retaining the contributions from the filamentary currents alone. The results have identically the form of Ufimtsev's expressions, in which the PO coefficients are subtracted from the non-PO coefficients. 
 This is a result of the direct and surface-reflected signals reinforcing and . TRACKING RADAR l 7S  canceling each other as the relative phase between the two paths varies. A change in frequency  also changes the phase relationship between the two signals. 
 PHASE CORRECTION FOR THE FIRST PULSE PAIR  AND  L  FOR THE SECOND PULSE PAIR ARE OPTIMIZED BY MINIMIZING THE INTEGRATED RESIDUE POWER OVER THE SIGNIFICANT PORTION OF THE ANTENNA PATTERN  USUALLY CHOSEN BETWEEN THE FIRST NULLS OF THE MAIN BEAM &IGURE  SHOWS THE SUM AND DIFFERENCE MAIN 
 George, S. F.: The 1)etection of Nonfli~ctiratirip Targets in Log-Normal Clutter. Naval Rtscnrcl~  i.(rl~orctror)~ Reporr h796. 
 The motivation for the Cassini  mapper was the same as that for Magellan ,  namely, to make measurements of the surface of Titan through its dense cloud cover.  During its extensive tour of the Saturnian system, the Cassini-Huygens mission was  to complete 35 flybys of Titan, of which 29 will be at the closest approach of less than  4000 km, of which 15 will have minimum altitudes of ∼1000 km. The first close flyby  was in November 2004, from which the first radar images of the surface were col - lected. 
 FERENT VALUES OF @  AND OTHER PARAMETERS 4HE ELECTROMAGNETIC PROPERTIES OF A BURIED TARGET MUST BE DIFFERENT FROM THE SUR 
 Sensors 2018 ,18, 1370. [ CrossRef ][PubMed ] 14. Li, Y.; Fu, Y.; Zhang, W. 
 J. Whitington, “HF radar ADC dynamic range requirements,” 3rd Int. Conf. 
 Three methods ofavoiding this modula- tion areavailable. Athigh PRF’s theheater current can beturned off after starting the system, since the cathode temperature will bemain- tained bybombardment. Alternatively thePRF can bemade anexact submultiple ofthepower-line frequency. 
 WAVE TUBES  AND OTHER FORMS OF TRANSMITTER FORMS ARE ROUTINELY USED 4HE DISTINGUISHING FACTOR BETWEEN METEOROLOGICAL RADAR AND OTHER KINDS OF AVIATION  OR MILITARY RADARS LIES IN THE NATURE OF WEATHER TARGETS  THE RESULTING CHARACTERISTICS OF THE RADAR SIGNAL  AND THE MEANS BY WHICH THESE WEATHER ECHOES ARE PROCESSED TO SUP 
 IT-3, pp. 122-131, June,  1957.  37. 
 CATIONS ASSESSMENTS ARE BASED ON %- SYSTEM PARAMETERS STORED IN A USER 
 Precision Analysis of Interferometric Phase For near-ﬁeld InISAR imaging system, to estimate the height information of target scattering point through the phase difference of corresponding pixel among complex images of various channels, it must ensure the consistency of strong scattering position among various channels images during 164. Sensors 2018 ,18, 3750 imaging of various channels. The accuracy of interferometric phase has a direct inﬂuence on imaging quality. 
 57. Wild, J. P.: Observational Radio Astronomy, Advances in Electronics and Electrot1 Phys~cs, vol 7,  1955. 
 19.6 RESEARCH APPLICATIONS Operational meteorological radars are designed for reliability and simplicity of opera - tion while providing the performance needed for operational applications. Research  radars are considerably more complex, since cutting-edge research requires more  detailed and more sensitive measurements of a multiplicity of variables simultane - ously. In the research community, multiple-parameter (polarization and wavelength)  radar studies, multiple doppler radar network studies, and a new generation of airborne  and spaceborne radars are receiving considerable attention. 
 The correlation mixer62,63 (CM)  in Figure 8.29 performs a bandpass multiplication of the received signal by the output  of the reference waveform generator. The lower sideband at the CM output is selected  by a bandpass filter (BPF).  Spectrum analysis is performed when the LFM slopes of the transmit and reference  waveforms are equal ( a = aR). 
 These aspects are the specular directions of the flat surfaces at either end of the frustum (O and 180° on the charts) and near the specular flash from the slanted side at 80°. The failure is due to a singularity in the diffraction coefficient Y along the reflec- tion boundary, and a similar singularity occurs in the diffraction coefficient X along the shadow boundary, a situation encountered in forward scattering. The singularities are overcome in the physical theory of diffraction (PTD) for- mulated by P. 
 Indeed, for angles very near grazing, this is the only satisfactory way to  resolve small regions. Many systems that use beamwidth to set the measured area  near vertical use range resolution for angles beyond, say, 60°. FIGURE   16. 
 SQUARED OF THE FOCUSED AND DETECTED BACKSCATTERED FIELD )N PRACTICE  MOST IMAGE PRODUCTS SUCH AS THOSE FROM THE %UROPEAN 3PACE !GENCYS 3!2S  USE MAGNITUDE  BECAUSE THE RESULTING IMAGERY HAS AN ACCEPTABLE APPEARANCE AND THE SIZE OF THE DATA FILE IS SMALLER THAN IF IN \MAGNITUDE\  )F SEVERAL DATA SETS OVER THE SAME SCENE ARE  COMBINED  OFTEN THESE ARE INDIVIDUALLY COLOR CODED  LEADING TO MULTICOLOR IMAGE PRODUCTS %ACH CONSTITUENT DATA SET MIGHT BE FROM A DIFFERENT POLARIZATION  WAVE 
 range limit, and adequate bandwidth inboth video amplifier and indica- tor system), the rate atwhich information ofalltypes iscollected is simply the rate atwhich separate echo pulses can bereceived. This rate would normally beabout l/T, diminished bythefactor I/N.. which takes account ofrepetition ofpulses from the same target. 
 The limited bandwidth of the majority of the schemes implementing Eq. (9.3) as compared with the wide band of a barrage jammer which can be regarded as a cluster, spread in angle, of narrowband jammers.28'30'34 4. The pulse width which limits the reaction time of the adaptive system, in order to avoid the cancellation of target signal.33 5. 
 P. Gerstoft, L. T. 
 .680 17.2 The Elements ofRadar Relay. 681 MISTHODS OFSCANNER DATA TRANSMISSION 17.3 General Methods ofScanner Data Transmission. 17.4 Methods ofCombating Interference 17.5 The Method ofIncremental Angle. 
 DOMAIN RADARS  BECAUSE OF THEIR LOWER )& RECEIVER BANDWIDTH AND HENCE THERMAL NOISE  BOTH THE TYPE OF RECEIVER AND THE RANGE SIDELOBES OF THE RADIATED SPECTRUM MAY RESULT IN AN EQUIVALENT OR WORSE SENSITIVITY IN TERMS OF RANGE RESOLUTION AS DISCUSSED ABOVE 0SEUDO 
 PASSIVE  FEED COMPONENTS 0HASED 
 fhe Butler networks in this section were assumed to use 3-dB directional couplers with a  90° phase difference between the two equal outputs. Hybrid junctions can also be used. These  produce a 180° phase difference between the two output signals and require a slightly different  design procedure. 
 Therefore !l.N = kYe B" G and  (9.6)  (9.7)  The system noise temperature I: is defined as the effective noise temperature of the receiver  system including the effects of antenna temperature T,,. (It is also sometimes called the system  Figure 9.1 Two networks in cascade. 346 INTRODUCTION TO RADAR SYSTEMS  operating noise temperature.60) If the receiver effective noise temperature is -~, then  'f:. 
 The frequency of spurious signals is also depen - dent on the input signal frequency with the highest values typically due to low order  harmonics or their aliases. When using IF sampling with a significant over-sampling  ratio ( fs  B/2), the worst spurious signals may be avoided by choosing the sample  frequency relative to signal frequency such that the unwanted spurious signals fall  outside the signal bandwidth of interest. If the worst case spurious can be avoided, the  specified SFDR is less important than the levels of the specific spurious components  that fall within the bandwidth of interest. 
 ,. ,,. .,”. 
 A more general case is that in which both the radar and the object are in motion. In ISAR, the target motion is often not known to the radar. Hence, a major part of the problem is determination of the target motion to generate the matched filter needed to generate an image. 
 (Optical photographs are generally taken from large grazing angles and  do not show the same shadowing effects produced by radar.) Stereoscopic techniques can also  be applied to SAR to provide a three-dimensional image or the terrain. This is accomplished  by viewing the same terrain from different aspects, such as by flying two separate flight paths  to produce images from two different elevation angles. 12 It is also possible to generate a pa1 r of  stereo images on a single pass using two vertical fan beams at different azimuth angles, or one  fan beam and a conical beam.13 The stereo processing of SAR images has been successfully  used for mineral exploration. 
 He states,  “In SAR, the target is assumed stationary and the radar is in motion. In ISAR, the  target motion provides the changes in relative velocity that cause different doppler  shifts to occur across the target” (pp. 375–380). 
 19.39.  34. Block, A .. 
 152–163. 60. E. 
 DEFENSE REQUIRE 
 D. Crombie, “Sea backscatter at HF:  Interpretation and utilization of the echo,” Proc. IEEE, vol. 
 Amoving target inthe 1The above discussion neglects thefactthat thephase-sensitive detector reduces thenoise voltage byv’% Thus Eq. (18) shOuld hem~lltiplied b.vW, aSshOtlld theordinate ofFig. 16.21. 
 K. Hughes, II, “Phased array parameter optimization for low- altitude targets,” in IEEE 1995 International Radar Conference, May 1995 pp. 196–200. 
 For these reasons, waveguide isalmost universally used forwavelengths below 8~cm. Inthelo-cm region where the size and weight ofthe Ii-by3-in. waveguide areawkward and the power-carrying capacity isnot needed, coaxial line isfrequently used. 
 GE-20, pp. 3–11, 1982. 11. 
 Table 7.1. Radiation-pattern characteristics produced by various aperture distributions  A.= wavelength; a= aperture width  Half-power  Relative beamwiqth, Intensity of first sidclohc,  Type of distribution, I z I < 1 gain deg dB below maximum intensity  Uniform; A(z) = 1 5 U/a 13.2  Cosine; A(z) = cos" (nz/2):  »=0 1 5 U/(l 13.2  II= 1 0.810 69.A./a 23  n = 2 0.667 83.A./a 32  n = 3 0.575 95.A./a 40  n = 4 0.515 llU/a 48  Parabolic; A(z) = 1 -(1 -A)z2:  A= 1.0 1 51.A./a 13.2  A= 0.8 0.994 53.A./a 15.8  A= 0.5 0.970 56)./a 17. l  A= 0 0.833 66)./a 20.6  Triangular; A(z) = 1 -l z I 0.75 73)./a 26.4  Circular; A(z) = Jl=----:? 0.865 58.5)./a 17.6  Cosine-squared plus pedestal;  0.33 + 0.66 cos2(nz/2) 0.88 63)./a 25.7  0.08 + 0.92 cos2(nz/2), Hamming 0.74 16.5)./a 42.8 \ / . 
 ,6"-9-/ 
 And there is a new family of radars, ultrahigh-frequency (UHF) and very-high-frequency (VHF) fixed-beam systems that are being used to obtain continuous profiles of horizon- tal winds.7 These examples are illustrative of the vitality of the field. This chapter is intended to introduce the reader to meteorological radar and particularly those system characteristics that are unique to meteorological appli- cations. In this regard, it should be noted that most meteorological radars appear *The National Center for Atmospheric Research is sponsored by the National Science Foundation. 
 Conceptually, such a matched filter is no different than a filter used to match a phase- coded pulse compression waveform. This is the basis of all SAR, RCS range imaging,  observed geometric target acceleration, turntable imaging, and ISAR. A ship in open water exhibits roll, pitch, and yaw motions about its center of grav - ity (c.g.). 
 In the monostatic case and a flat earth, these isodops are conic sections in three dimensions and radial lines emanating from the radar in two dimensions. In the bistatic case the isodops are skewed, depend- ing upon the geometry and kinematics. They are developed analytically for two dimensions and a flat earth by setting fTR = constant in Eq. 
 Remote Sens. 2018 ,10, 270. [ CrossRef ] 37. 
 TYPE FILTER IS BEING USED AND  &)'52%  B  4HIRTY 
 Theopposite istruein themillimeter-wave region.)Theeffectofafogwith300-mvisibility isseentoincrease slightly theclear-air attenuation. Afair-weather cumulus cloudhaslowattenuation atmillimeter wavelengths. Aone-way attenuation of0.3dBjkmat94GHzmightnotbesignificant forshort-range radar,butitcanbeoverwhelming forlong-range radar.Forexample, a5-kmradarwill experience atwo-way attenuation of3dB,whichistolerable inmostsituations. 
 In air  defense, radar is used for long-range air surveillance, short-range detection of low- altitude “pop-up” targets, weapon control, missile guidance, noncooperative target  recognition, and battle damage assessment. The proximity fuze in many weapons is  ch01.indd   20 11/30/07   4:34:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Thistechnique notonlyimproved significantly thetracking accur­ acyascompared withalongerpulseconventional tracker, butitsuniquemeasurement properties provideadditional capabilities. Forexample, itcanbeusedasameansoftarget classification orrecognition, asaprecision vectormiss-distance indicator foruninstrument,ed targets,asacounter(ECCM) torepeater jammers, asanaidinlow-angle tracking, andasa meansfordiscriminating unwanted clutterorchafffromthedesiredtarget. '.Tracking indoppler. 
 819-827, October, 1973.  23. hlillman. 
 Applica-  tions for limited-scan arrays in radar have included the one-dimensional electronic scan of 3D  radars (Sec. 14.4), aircraft landing or ground-control approach (GCA) radars,''' and hostile-  weapon-location radars. ' s'  8.11 APPLICATIONS OF THE ARRAY IN RADAR  The phased-array antenna has been of considerable interest to the radar systems engineer  because its properties are different from those of other microwave antennas. 
 For this condition to exist, the weather must be calm withlittle or no turbulence, otherwise the layers of different densities will mixand the boundary conditions disappear. The effect of super-refraction willincreasethedownwardbendingoftheradarraysandthusincreasetherangesat which targets may be detected. Super-refraction frequently occurs in thetropics when a warm land breeze blows over cooler ocean currents. 
 Neri, Introduction to Electronic Defense , 2nd Ed., Norwood, MA: Artech House, Inc., 2001.   7. L. 
 Thus to reduce  the sidelobes to a level of -30 to -40 dB results in a loss in peak signal-to-noise ratio of from  one to two dB. For many applications the beam broadening and the loss in peak signal-to-  noise ratio due to mismatch are usually tolerated in order to achieve the benefits of the lower  sidelobes.  Instead of weighting the received-signal spectrum to reduce the time sidelobes, it is  possible, in principle, toachieve the same affect by amplitude-weighting either the envelope of  transmitted FM signal or the received signal. 
 65. W. C. 
 Since the beamwidth of such an antenna is given by the ratio of the wavelength X to its horizontal aperture D, the maximum length of this synthetic antenna aperture is given by La = f (21.3) The linear resolution in azimuth 8a is the product of the effective beamwidth given by Eq. (21.2) and the range R: 8a = Peff* (21.4) If Eqs. (21.2) and (21.3) are combined with Eq. 
 Coleman: Virtual Source Luneburg Lenses, Symposium 011  Micrmrnre Optics, McGill University, Montreal. AFCRC-TR-59-118(1), ASTIA Document 211499.  rr 18-21. 
 The geometry issochosen that theSchmidt correcting plate comes roughly atthe neck ofthe cathode-ray tube. A 45°mirror reflects thelight toahorizontal projection screen which forms part ofthetop ofthecabinet housing theequipment.. SEC. 
 MODULATION  AND IN 
 An example of the display, Chapter 21 ch21.indd   1 12/17/07   2:50:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 
 TIVELY WIDE TO COPE WITH THE SHIPS PITCH AND ROLL  WHICH IS ASSUMED TO BE A MAXIMUM OF o 5SE OF A STABILIZED PLATFORM WOULD NOT MEET THE MARKETS  PRICE DEMANDS   4HIS LIMITS THE VERTICAL BEAM 
 IEEE Trut~s.. vol. AP-25, pp. 
 95. J. Ward, “Space-time adaptive processing for airborne radar,” MIT Lincoln Laboratory Technical  Report TR–1015, December 13, 1994. 
 Batt, R. J.. and D. 
 ATION WARNINGS  4ORNADO $ETECTION  ! SINGLE DOPPLER RADAR CAN MEASURE ONLY THE RADIAL COMPO 
 17.10 signal strength asafunction ofrange for frequencies of100, 300, and 850 Me/see, displaying the effect offrequency onthe number and the magnitude ofthe fluctuations insignal strength that are due to interference. Figure 17.16 shows curves ofsignal strength asa function ofrange for receiver antenna heights of75, 110, and 140ft above thesurface ofthesea. These curves indicate themanner inwhich theeffects ofsignal cancellation can bereduced byusing diversity recep- tion with antennas atdifferent heights. 
 44-54, January, 1957.  19. Wright, J. 
    
 5–18, 1987. 107. A. 
 "AND SOLID  
 1958.  36. Capelli, M.: Radio Altimeter, IRE Trans., vol. 
 Va.IEEEPublication 77CB1255-9EASCON. 20.Barker.Ci.(j.:CFAorTWT?WhichValveWillBestMeetYourTransmitter OutputStageRequire­ Illcnts;lEECIIIlt:PI/hI.No.[05."Radar -Present andFuture," London, Oct.23-25, 1973. pp.IX9194. 
 FORM WITHOUT PHASE DISCONTINUITIES 1UADRIPHASE CODES  ARE BASED ON THE USE OF  SUBPULSES WITH A HALF 
 The primary difference is the increased attenuation ov er the range of the measurement  signal, which travels twice along the path from the measurement antenna to the measurement  object.  Measuring paths in absorption chambers the attenuation is 100  dB to 150  dB for co m- mon measuring distances of 10 to 20 m.  In  large free -space test ranges the attenuation is co n- siderable higher. 
 If the target is successfully  acquired, a track file in the radar computer is initiated. The Track Acquisition wave - form’s parameters depend upon the type of search waveform that produced the target  detection. The Track Acquisition waveform’s thresholds are set to reject false alarms  and reduce the false track initiation rate to less than one per hour . 
 Davenport, W. B., Jr., and W. L. 
 The question of whether detections or  tracks should be integrated is a function of the application. In a military situation, by  integrating detections one could interrogate the target only a few times, identify it,  and then associate it with a radar track. From then on, there would be little need for  re-interrogating the target. 
 These noise maps pro- vide the level that an omnidirectional antenna would receive. The common method of use is to treat the noise as isotropic even though it must be azimuth- and elevation-angle-dependent. Examination of maps indicates that tropical rain forests and other regions of concentrated thunderstorm activity are major sources of noise. 
 The latter occurs wlieii  Nn(t1lJ.) sin O = 0, _t n, f 2n, . , 2 ~ln, where 11 = integer. The denominator, however, is zero  when n(tl/A) sin 0, = 0, f n, + 2rr, . 
 In order  to recognize and suppress these unwanted returns, which can obscure target echoes,  an understanding of the underlying physics is essential. A distinctive requirement of a skywave radar is a suite of auxiliary systems to mon - itor the state of the ionosphere and the availability of unoccupied channels in which  to operate. This reliance on continuous environmental monitoring and the associated  ability to adapt the radar parameters and tasking to make best use of the prevailing  conditions cannot be satisfied with simple, low dynamic range equipment, for that  would fail to reveal many of the phenomena that are setting the threshold for target  detection and tracking. 
 As O approaches O degrees, the required in•egr ttion  lime T becomes loo large to provide beam sharpening so that improved resolution is not  obtained in a finite angular sector about the direction of the vehicle velocity.  In the telescope, or spotlight, mode very high resolution of a particular patch on the  ground is obtained by steering the real antenna aperture to dwell longer than is possibk with a  fixed antenna. Theoretically, resolutions better than D/2 can be obtained. 
   ")34!4)# 2!$!2   ÓÎ°Ó£ LARGE DISCRETE SCATTERING CENTERS  FOR EXAMPLE  THROUGH SHADOWI NG  TARGET GLINT IS OFTEN  REDUCED 4ARGET GLINT IS THE ANGULAR DISPLACEMENT IN APPARENT PHASE CENTER OF A TARGET  RETURN AND IS CAUSED BY THE PHASE INTERFERENCE BETWEEN TWO OR MORE DOMINANT SCATTERS WITHIN A RADAR RESOLUTION CELL !S THE TARGET ASPECT ANGLE CHANGES  THIS PHASE INTERFER 
 A waveguide ceramic window is  necessary to maintain the vacuum in the tube and yet couple power out efficiently. Wavegiride  arcing or thermal stresses are common causes of window failures. High-power tubes  sometimes employ an arc detector looking directly at the output window that allows either the  drive power to be removed or the beam to be shut off within a few tens of microseconds after  the presence of an' arc is detected. 
 Although we may conceive of apparent  sources being strung out behind any physical scattering obstacle due to time delays of  multiple reflections, it is hard to reconcile them being strung out in front  of the body.  We do see several clusters of apparent scattering centers positioned aft of the tail of  the aircraft, but lacking any detailed description of the test object, we cannot interpret  their meaning. These “ghost” scatterers owe their existence to the way in which the data-processing  system sorts the range and cross-range locations of scatterers. 
 28 2.7 Noise .......... .. 28 2.8 Receivers, Ideal and Real. 
 Their purpose is typically to detect, identify, and locate transmitters such as monostatic radars. They are also called emitter locators. Target location is by means of combined angle measurements from each site (e.g., triangulation), TDOA, and/or differential doppler measurements be- tween sites. 
 CODED PULSE COMPRESSION WAVEFORM 4HIS IS THE BASIS OF ALL 3!2  2#3 RANGE IMAGING  OBSERVED GEOMETRIC TARGET ACCELERATION  TURNTABLE IMAGING  AND )3!2 ! SHIP IN OPEN WATER EXHIBITS ROLL  PITCH  AND YAW MOTIONS ABOUT ITS CENTER OF GRAV 
 Skolnik (ed.), New York:  McGraw-Hill, 1990, pp. 323–325. 52. 
 Both the transistor and the diode microwave  generators are characterized by low power, as compared with the power capabilities of the  microwave tubes discussed previously in this chapter. The low power, as well as otllcr cliarac-  teristics, make the application of solid-state devices to radar systems quite different from  high-power microwave tubes. The almost total replacement of receiver-type vacuum tubes by  solid-state devices in electronic systems has offered encouragement for replacing the power  vacuum tube with an all solid-state iransmitter to obtain the advantages offered by that  _'a ,,I I . 
 The dotted curve isthecorresponding contour with anonreflecting earth. Both contours would usually bemodified bythedirectional pattern ofthe. SEC.2.14] SUPERREFRAC TION 55 radar antenna and itisnot difficult totake this into account inthe calculation. 
 LOOKING 3!2 "Y THE END OF THE MIS 
 AXIS IN  &IGURE   PRODUCES AN EVEN 
 #/5.4%2-%!352%3   Ó{°ÎÇ 4HE OPERATIONAL METHODS INCLUDE EMISSION CONTROL %-#/.   THE APPROPRIATE  ASSIGNMENT OF OPERATING FREQUENCIES TO VARIOUS RADARS  THE USE OF COMBINED %##-S  TO MEET COMBINED %#-S  THE USE OF DUMMY TRANSMITTERS TO DRAW %#- TO OTHER FRE 
 As a new application, the spectral analysis (SPECAN) [ 15,16] algorithm was used to process the MPS SAR signal in elevation. The residual phase induced by varying center distance Rn(r)was ﬁrst compensated by multiplying the signal with its complex conjugate phase: H(r,n)=exp⎭braceleftBig j4π λRn(r)⎭bracerightBig ≈exp⎭braceleftBigg j4π λ⎭parenleftBigg⎭radicalBig⎭parenleftBig r+B//, n⎭parenrightBig2+B2a,n+B2 ⊥,n⎭slashBigg⎭parenleftBigg 2⎭radicalBig⎭parenleftBig r+B//, n⎭parenrightBig2+(Ba,n)2⎭parenrightBigg⎭parenrightBigg⎭bracerightBigg . (5) After multiplication, the signal was modeled as: sn/prime(y/prime,r/prime)=⎭radicalbigσp·sin c⎭parenleftBigg r/prime−r ρr⎭parenrightBigg ·sin c⎭parenleftBiggy/prime ρa⎭parenrightBigg ·exp⎭braceleftBigg −j2πfd,ny/prime v⎭bracerightBigg , (6) Then, a new variable ξn(diﬀerent from that in [ 15,16]) was designed to focus the signal in elevation by the single Fourier transform (FFT), to give: ss(y/prime,r/prime,s)=⎭summationtext2N+1 n=1(sn/prime(y/prime,r/prime)·exp⎭braceleftbig−j2πξ ns⎭bracerightbig)≈(2N+1)√σp·sin c⎭parenleftBigr/prime−r ρr⎭parenrightBig ·sin c⎭parenleftbigg y/prime ρa⎭parenrightbigg ·sin c⎭parenleftbigg s+y/primecotα/sinθ ρe⎭parenrightbigg (7) where, ξn=2B⊥,n⎭slashBigg⎛ ⎜⎜⎜⎜⎜⎝λ⎭radicalbigg ⎭parenleftBig r+B//, n⎭parenrightBig2+(Ba,n)2⎞ ⎟⎟⎟⎟⎟⎠≈2B⊥,n/(λr), (8) ρeis the resolution in elevation, given by [ 12]: ρe≈λr⎭slashBig⎭parenleftBig 2B⊥,total⎭parenrightBig . 
 Illus- trated in Fig. 17.1 is the received pulsed spectrum with returns from continuous clutter, such as the ground or clouds, and from discrete targets, such as aircraft, automobiles, tanks, etc. Figure 17.2 shows the unfolded spectrum (i.e., no spectral foldover from ad- jacent PRF lines) in the case of horizontal motion of the radar platform, with a velocity VR. 
 (Thegroupvelocity isthevelocity withwhich energy ispropagated alongtheslow-wave circuit,andthephasevelocity isthevelocity ofthe RFsignalontheslow-wave circuit asitappears totheelectrons. Toachieve RF Figure6.12Simpierepresentation ofa crossed-field amplifier. (FromClam­ "itt,6Electronic Progress, RaytIJein.)"'-DiSCharge path9Energy -~ storage>- ceelement----=-=~--~--:::'I ( , II ,,It'-- SwitchI I Load ~•I~ ,I I I I,I\ I 0+----\=---<---- .Jf---0+---(---.- t 1Chargin impedan Energy sourcelibr / CtlOrging path/. 
 STAP can improve a radar’s  motion compensation performance and is more robust than nonadaptive techniques  in addressing generally non-dispersive errors in the radar front-end. STAP will not  directly address clutter internal motion effects, antenna scanning motion effects, or  other hardware stability impacts to clutter cancellation performance. Radar designers  need to assess the key limitations in a specific application before jumping to the con - clusion that STAP will improve performance. 
 SET IN SPACE AND PROVIDES A PARTIALLY OR FULLY INDEPENDENT MEASUREMENT OF AN INCOMING ELECTROMAGNETIC WAVEFRONT &OR EXAMPLE  A ONE 
 Denniss “Solid-state linear FMCW systems –their promise and their problems,” in Proc. IEEE  Int. Mic. 
 Three other hybrid models are Radio Physical Optics (RPO),19 TERPEM authored by  Signal Science Limited,20 and a hybrid method for computing transmission losses in  an inhomogeneous atmosphere over irregular terrain by Marcus.21 Within APM, the assessment space is divided into four regions, or submodels, as  illustrated in Figure 26.8. At ranges less than 2500 m and for all elevation angles  above 5°, APM uses a flat earth (FE) model that ignores refraction and earth curvature  effects. For ranges beyond the FE region where the grazing angles of reflected rays  from the transmitter exceed a small limiting value, a full ray optic (RO) model is used  that accounts for the effects of refraction and earth curvature. 
 Range-accuracy -leading-edge measurement. The measurement of range is the measurement of  I ime delay TR = 2R/c, where c is the velocity of light. One method of determining range with a  pulsed waveform is to measure the time at which the leading edge of the pulse crosses some  threshold 1 (Fig. 
 The block diagram of the MTD II signal processor is shown in Figure 2.7. Parallel  processing channels are provided for moving targets through the two-pulse MTI can - celer and the seven-pulse doppler filter bank, and for nonmoving (“zero-doppler”)  targets through the 0-Velocity Filter. A high resolution clutter map is built from the  “0-Velocity Filter” output, and the clutter map content is used for thresholding in the  two processing channels. 
 W. Hancock, G. S. 
 Larson et al., “Bistatic clutter measurements,” IEEE Trans. , vol. AP-26, pp. 
 ⇒ CW Doppler Radar, only moving targets,   - Measurement of the phase shift of the receiving signal.   ⇒ Interferometry  - Frequency modul ation of the transmitting signal.   ⇒ FM CW Radar. 
 Remote Sens. 2007 ,45, 506–511. [ CrossRef ] 4. 
 PULSE WIDTH IS  S . 4HESE RELATIONSHIPS ARE  SUMMARIZED IN 4ABLE   3HAPING OF THE HIGH 
 MATED BY TREATING THE SHADOW AREA  ! AS A UNIFORMLY ILLUMINATED ANTENNA APERTURE 4HE  RADIATION PATTERN OF THIS  SHADOW APERTURE IS EQUAL TO THE FORWARD 
 Contextual region-based convolutional neural network with multilayer fusion for SAR ship detection. Remote Sens. 2017 ,9, 860. 
 Unterminated lines have been used, but the high-frequency response is greatly impaired. Although lines of1000-ohm characteristic impedance have been made and are fairly satisfactory forlengths of20ftorless, longer lines areusually standard 75-or100-ohm coaxial cable. Todrive such aline from the plate ofanamplifier requires avery large coupling condenser; hence the cathode-follower circuit shown asthe second stage inFig. 
 The detection performance of the batch processor for a large number of pulses integrated is approximately 0.5 dB worse than the moving window. The batch processor has been successfully implemented by the Applied Physics Laboratory21 of Johns Hopkins University. To obtain an accurate azimuth esti- mate 6, approximately 20 percent greater than the lower bound, *-^? *-> is used, where E1 is the batch amplitude and O1- is the azimuth angle corresponding to the center of the batch. 
 19. B. Cantrell, “ADC spurious signal mitigation in radar by modifying the LO,” in Proceedings of  the 2004 IEEE Radar Conference,  April 26–29, 2004, pp. 
 95. J. DiBartolo, W. 
 Nevertheless, itmaybestatedthatwhenever theapriori probabilities areknown, theinverse-probability method maybeusedwithconfidence. When theaprioriprobabilities arenotknown, thelikelihood-ratio testisusuallyemployed. Relationship ofinverseprobability andlikelihood-ratio receivers. 
 Nicholas III and H. Samueli, “An analysis of the output spectrum of direct digital frequency  synthesizers in the presence of phase-accumulator truncation,” Proceedings. 41 st annual Frequency  Control Symposium , USERACOM, Ft. 
 Such pressurization ofthe modulator and the r-fsystem increases theproblems ofcooling. Tomeet operating conditions onthe ground inthetropics, the radar must operate indefinitely atanambient tem-. 614 EXAMPLES OF RADAR SYSTEM DESIGN [SEC. 
 CIAL AND UNIVERSITY CODES HAVE BEEN DEVELOPED FOR THE ANALYSIS  AND DESIGN OF REFLEC 
 2.8, rather than by the n112 law.  The radar equation with n pulses integrated can be written  4 P,GAea  Rmax = (4n)2kT0Bnf11(S/N) 11 (2.32)  where the parameters are the same as that of Eq. (2.7) except that (S/N)11 is the signal-to-noise  ratio of one of the n equal pulses that are integrated to produce the required probability of  detection for a specified probability of false alarm: To use this form of the radar equation it is  necessary to have a set of curves like those of Fig. 
 A. Gray, Y . I. 
 Intheory,thescattered field,andhencetheradarcrosssection,canbedetermined by solvingMaxwell's equations withtheproperboundary conditions applied.16Unfortunately, thedetermination oftheradarcrosssectionwithMaxwell's equations canbeaccomplished onlyforthemostsimpleofshapes,andsolutions validoveralargerangeoffrequencies arenot easytoobtain.TheradarcrosssectionofasimplesphereisshowninFig.2.9asafunction of itscircumference measured inwavelengths (2na/A.,whereaistheradiusofthesphereandA.is thewavelength).17-19.34 Theregionwherethesizeofthesphereissmallcompared withthe wavelength (2nalA. ~I)iscalledtheRayleigh region,afterLordRayJeigh who,intheearly 18705,firststudiedscattering bysmallparticles. LordRayleigh wasinterested inthescattering oflightbymicroscopic particles, ratherthaninradar.Hisworkpreceded theorginalelectro­ magnetic echoexperiments ofHertzbyaboutfifteenyears.TheRayleigh scattering regionisof. 
 Theazimuth resolution andaccuracy obtained bythe1.25°beamwidth issaidtobe2°and0.2°,respectively.46 The antenna canhehOllsedina17.4m(57ft)diameter rigidgeodesic-radome. TheARSR-3 antenna generates twobeamsslightlydisplaced inelevation forthepurpose ofreducing theechoesfromhigh-speed surfaceclutter,suchasfromautomobiles andtrucks. Theseclutterechoescanbelargeenoughandhaveasufficiently highdoppler frequency shift. 
 A. Sletten and J. C. 
 ARRAY RADAR  0!2  WITH THOUSANDS OF ELEMENTS  IT IS NOT POSSIBLE TO ADAPT DIRECTLY THE SIGNALS FROM EACH RADIATING ELEMENT )T IS NECESSARY TO REDUCE THE SYSTEM COMPLEXITY BY USING SUB 
 TION ! FINER 
 This would be adverse to the corresponding long-term analysis and deformation interpretation following highway construction. According to authoritative statistics, more than 70% of pavement structure damage is related to long-term rheological deformation of the subgrade [ 27]. The rheological property is one of the primary engineering properties of soft soil, representing the temporal e ﬀect of soil deformation. 
 The amplitude-comparison feed is designed to sense any feed plane displacement  of the spot from the center of the focal plane. A monopulse feed using the four-horn  square, for example, would be centered at the focal plane. It provides symmetry  so that when the spot is centered, equal energy falls on each of the four horns. 
 It can perform observations on the ground all day and in all weather conditions. Now we can get more high-resolution SAR images by recent development of SAR satellites, e.g., RADARSAT-2, TerraSAR-X [ 1,2], etc. By using these images, lots of applications can be implemented. 
 K. Davies, Ionospheric Radio,  London: P. Peregrinus, 1990. 
 68. J. T. 
 K. Raney, and L. A. 
 [Equation (7.10)  applies to a one-dimensional line source lying along tllc 2 axis. For tllc two-dirnc~lsior~al  aperture of Fig. 7.2, A(z) is the integral of A(x, z) over the variable x.]  Equation (7.10) represents the summation, or integration, of the individt~al contributions  from the current distribution across the aperture according to tluygclls' principle. 
 This process results in a delayed beam and an undelayed beam, whose phase centers are offset to compensate for platform motion. If jamming is present in the sidelobes or on the shoulder of the main beam, nulls will be formed in each jam- ming direction. If mixed clutter and jamming are present, the weights will adjust to maximize the signal-to-total-interference ratio. 
 14.20, when themachine isatrest thecarbon pile isheld incompres- Alternator fwld h filterContactor ..AL~~~ .Itemator Cabwle I ;,S1l, ~,;gt A-cfifter =Ofi1 T%ries fwld Voltage adwstmg “’’’t”’-f-l&q.FIG.14.22 .4chematic diagram ofWincharger PU-16 aircraft inverter, 750va,115volts, 400Cps. sion bythe large coil spring inthe rotating element. The resistance isthen least, giving maximum field forgood starting characteristics. 
 Int. Symp. Electromagn. 
  
 ¤ ¦¥³ µ´ T T PT PT P A T T T P A AFT FT TD2 2 )&         
 III ** 22 10.5 ASV Mk. VI ** 32 20.5ASV Mk. VII * 18 10.0 Table 7.3. 
 Even under benign conditions, the ionosphere seldom supports highly coher - ent propagation over bandwidths greater than ~200 kHz, even when clear channels  wide enough to accommodate such waveforms are available, which is infrequently.  More typically, clear channels range from 10–50 kHz, so the waveform bandwidth  is normally chosen to lie in this range. The corresponding range resolutions extend  ch20.indd   8 12/20/07   1:15:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 TION AND MEASUREMENT OF VARIOUS TARGET CHARACTERISTICS &OR EXAMPLE  THE RADAR OPERATOR MIGHT SELECT A SEARCH MODE AND SPECIFY A SEARCH  VOLUME THAT THE RADAR WILL RASTER SCAN  AS SHOWN IN &IGURE  6ALID DETECTIONS IN SEARCH ARE THEN CONVERTED TO TRACKS IN THE RADAR COMPUTER 4HESE TRACKS NEED TO BE UPDATED BY A TRACK MODE ON A REGULAR BASIS DEPENDING ON THE TRA CK ACCURACY REQUIRED  (IGH TRACK ACCURACY IS NEEDED FOR THREATENING TARGETS OR THOSE THAT NEED A FIRE CONTROL 4!",%  4HREE 
 #/5.4%2-%!352%3   Ó{°Óx DEPICTS THE PRESENCE OF THE TARGET AS WELL AS OF THE JAMMING )T HAS BEEN DEMONSTRATED  THAT -ONTE #ARLO SIMULATION IS IN CLOSE AGREEMENT WITH #2," ANALYSIS )T HAS BEEN FOUND THAT THE USE OF THE FOUR 
 OUSLY OR IN DISCRETE STEPS VARYING THE 2& CARRIER  WITH EITHER LINEAR OR SINUSOIDAL &- OR SOME FORM OF PULSE MODULATION SUCH AS PULSE 
 The presence of the various refracting regions with different  ionization densities at different altitudes requires good frequency management if an 0TH  radar is to operate with reliability.  The minimum range to which'HF1energy can be propagated by ionospheric refraction is  determined by the lowest frequency at which the radar can operate. A nominal value for the  minimum range (or skip distance) is about 1000 km. 
 Time-Series Deformation Model Suppose M+1 SAR images covering the same area are acquired in repeat orbits at di ﬀerent dates. Then, Ninterferometric pairs may be generated, according to certain temporal baseline and spatial baseline thresholds, where the Ninterferometric pairs are generated through two-orbit D-InSAR processing, while satisfying the inequalityM 2≤N≤M(M−1) 2. In the processing, all images are registered and resampled to the same image ﬁrst. 
 20.5 Functional monopulse processing implementations, (a) Full-vector monopulse pro- cessing, (b] Full-vector monopulse with prehybrid combining, (c) Amplitude-only monopulse pro- cessing, (d) Phase-only monopulse processing.(d)ANTENNA XMTRTRANSMITTER CIRC.£RCVRCSP MONOPULSETABLE ARCVR CSP RECEIVERS COHERENTSIGNALPROCESSING ANTENNA XMTR CIRC. LOW-NOISEAMPLIFIERHYBRIDJUNCTION SUMRCVR CSP MONOPULSETABLE LOW-NOISEAMPLIFIERCSPDIFFRCVR HYBRIDJUNCTIONRECEIVERS COHERENTSIGNALPROCESSING (b) ANTENNA XMTRTRANSMITTER CIRC.SUMRCVRCSPENV.DET.MONOPULSETABLE 0DET. DELTARCVR CSPENV.DET. 
 Thereexistinthe literature thenecessary graphsandnomographs whichsimplify thecomputation ofradar coverage.59Computers maybeusedtoperform thecalculations andtoautomatically plotthe coverage patterns bycomputer-controlled plotting machines.! 0Figure12.4illustrates, fora particular case.thecomputed vertical-plane radarcoverage patterns for(a)horizontal polari­ lationand(II)vertical polarization. 12.4REFRACTION Radioandradarwavestravelinstraight linesinfreespace.However, electromagnetic waves propagating withintheearth'satmosphere donottravelinstraight linesbutaregenerally bent orrefracted. Oneeffectofrefraction istoextendthedistance tothehorizon, thusincreasing. 
  &RANCE n     #  +U9ES  %NVISAT %3! n     3  +U 9ES  *ASON 
 H., and D. D. Howard: The Effects of Automatic Gain Control Performance on the Tracking  Accuracy of Monopulse Radar Systems, Proc. 
 59, pp. 101–102, January 1971. 26. 
 Green Jr., “Radar measurements of target scattering properties,” in Radar Astronomy ,   J. V . Evans and T. 
 Cont. 303. Sensors 2019 ,19,6 3     (d) ( e) ( f)      (g) ( h) ( i)  Figure 11. 
 FromtherearhaIrorthecone-sphere, theradarcrosssectionisapproximately thatofthe sphere. Thenose-on crosssectionofthecone-sphere varies,butitsmaximum valueisapproxi­ mately0.4),2anditsminimum is0.0U.2forawiderangeofhalf-angles forfrequencies above theRayleigh region.TheHullspacing isalsorelatively insensitive totheconehalf-angle. Ifa "typical" valueofcrosssectionistakenas0.1),2,thecrosssectionatSband(A=0.1m)is 103m2,andatXband(A=3cm),thecrosssectionisapproximately 10-4m2.Thus,in theory.thecone-sphere canhaveverylowbackscatter energy.Suppose, forexample, thatthe projected areaofthecone-sphere were1m2•Theradarcrosssectionofasphere,withthesame projected area,atSbandisabout30dBgreater.Acornerreflector atSband,alsoofthesame projected area,hasaradarcrosssectionabout60dBgreaterthanthecone-sphere. 
 However, amplitude errors in driving stages will cause drive-induced phase variations in the following stages, as noted above, all of which must be counted. 3. Time jitter in cascaded stages simply adds unless they are arranged to can- cel or to be root-sum-squared, as discussed in Par. 
 C. MacDonald, and R. Shewbridge, “Radar terrain reflections for several polar - izations and frequencies,” in Proc. 
 I," R. E. Collin and F. 
 The target-caused errors discussed in Section 9.8 include the usual tracking  events where the target extent is within the 3-dB beamwidth of the radar. However,  a large target such as an aircraft formation may extend beyond the linear angle-error  region of the antenna patterns and eventually reach the point of resolution of one  of the aircraft. The resultant angle-tracking error for large targets is illustrated by  the example in Figure 9.31. 
 BASED SOUNDER  AND THE NEED TO SALVAGE ALL  POSSIBLE CONTRIBUTIONS OF SIGNALS FROM  DEPTH  IT IS STANDARD PRACTICE TO ASSUME THAT THE  DOMINANT IN SITU RETURNS ARISE FROM SPECULAR SCATTERING  HENCE FROM EXTENDED HORIZONTAL LAYERS  4HE CONTRIBUTING AREA IS DETERMINED BY THE RADIUS  R& OF THE FIRST &RESNEL ZONE   RH& L IN FREE SPACE  WHERE  H IS THE ALTITUDE OF THE RADAR ABOVE THE SURFACE 4HE  RADIUS IS SOMEWHAT LARGER WITHIN THE MEDIUM  SINCE THE SPHERICAL WAVEFRONT IS FLAT 
 JAMMING RATIO    DISCRIMINATION OF DIRECTIONAL INTERFERENCE    REJECTION OF . 
 These are all characteristics of sea  clutter at low grazing angles. The probability distributions of low grazing angle sea clutter change with wind  speed. Examples may be found in the measurements by Trizna of low-angle sea clut - ter using high-resolution (40-ns) shipboard radar in both the Atlantic and the Pacific  oceans.42 The probability distributions of the clutter cross sections were plotted in the  manner shown in Figure 15.12, which shows the distributions of horizontally polar - ized X-band data at a 3° grazing angle for low, medium, and high wind speeds (in order  from left to right). 
 I. Sheftman, and D. A. 
 7.2.—Control boxofaircraft odograph ordead-reckoning computer.inFig. 7.2. Wind velocity isre- solved into components along the north-south and east-west direc- tions, integrated, and. 
 ITY 6ISIBILITY  IS DEFINED AS hTHE GREATEST DISTANCE IN A GIVEN DIRECTION AT WHICH IT IS JUST  POSSIBLE TO SEE AND IDENTIFY WITH THE UNAIDED EYE    IN THE DAYTIME  A PROMINENT DARK  OBJECT AGAINST THE SKY AT THE HORIZON AND   AT NIGHT A KNOWN  PREFERABLY UNFOCUSED  MODERATELY INTENSE LIGHT SOURCEv !LTHOUGH THE VISIBILITY DEPEN DS UPON BOTH DROP SIZE  AND NUMBER OF DROPS AND NOT ENTIRELY UPON THE LIQUID 
 6.2a. Slots  have also been employed. When large and small slots are alternated, as in the rising-sun  magnetron structure of Fig. 
 The region of i~nambiguous range may be extended considerably by utilizing two separate  CW signals differing slightly in frequency. The unambiguous range in this case corresponds to  a half wavelength at the difference frequency.  The transmitted waveform is assumed to consist of two continuous sine waves of  frequency f, and 1; separated by an amount AJ For convenience, the amplitudes of all signals  arc set equal to unity. 
 GAIN ANTENNA TO RETRO 
 One aperture distribution which has been  considered in the past1 is [I -(r/r0)2)P, where p = 0, 1, 2, .... The radiation pattern is of the  form Jr+ ,(e)/eP+ 1. When p 0, the distribution is uniform and the radiation pattern reduces  to that given above. 
 PLANE AS DESIRED FOR THE IDEAL FIELD SHAPING   &)'52%    4WELVE 
 December, 1975.  9 1. Tomiyasu. 
 02& RADAR  ESPECIALLY AT HIGHER ALTITUDES  THE RELATIVE AMPLITUDES OF THE DISTRIBUTED SIDELOBE CLUTTER AND THE DISCRETE RETURNS ARE SUCH THAT THE DISCRETES ARE NOT VISIBLE IN THE SIDELOBE CLUTTER 4HE APPARENT RADAR CROSS SECTION 2#3    R APP  OF A SIDELOBE DISCRETE WITH AN 2#3  OF R IS RAPP   R '3,  WHERE '3, IS THE SIDELOBE GAIN RELATIVE TO THE MAIN BEAM 4HE  LARGER 
 70, 1). I I* t.el)l.[  ary. 1936. 
 Target trackers from individual manufacturers can have quite different  design and optimization strategies and can, therefore, differ in performance. Within  IEC 62388,11 there are defined test scenarios that all SOLAS-approved tracking sys - tems must meet. IMO requires that the trend in a target’s change of direction is shown  within one minute and the prediction of the target’s motion should be available within  three minutes, as given in Table 22.4. 
 Sel. T op. Signal Process. 
 ,- 4HE HIGH 
 AXIS TO POINTS ON THE REFLECTOR  SURFACE  A  ¤ ¦¥³ µ´  ARCTANXY F   . 
 Inthe second case (high PRF and broad beam) the predominating fluctuations will bedue tosystem instability and maybe oftheorder of5 percent (peak) ifallthe stability requirements are met. Thus peak receiver noise should inthis case besetat5percent oflimit level. 16.9. 
 Polge: Performance of the g-h Filter for Tracking Maneuvering Targets,  I F.F.E Tre111., .. vol. AFS-10. 
 TO 
 FS D"    WHERE ,FS IS THE FREE 
 Ia. Ufimtsev, “Approximate computation of the diffraction of plane electromagnetic waves at  certain metal boundaries, Part II: The diffraction by a disk and by a finite cylinder,” Zh. Tekhn. 
 Shnidman and S. S. Toumodge, “Sidelobe blanking with integration and target fluctuation,”  IEEE Trans ., vol. 
 COUNTER REGISTERS THAT RETAIN NUMBERS CORRESPONDING TO TARGET RANGE TO PROVIDE A CLOSED RANGE 
 TRACKING GATES ON  THE ECHO PULSE PRIOR TO LOCKING ON THE TARGET OR CLOSING THE TRACKING LOOPS 4HE GATE ACTS LIKE A FAST 
 RANGE ERROR RCR IS PROPORTIONAL TO ; SIN @   =  
    AND ITS COVARIANCE MATRIX  0K 
 Surface subsidence analysis by multi-temporal insar and grace: A case study in Beijing. Sensors 2016 ,16, 1495. [ CrossRef ] 21. 
 VERTER 4HE 'RAY CODE ALLOWS ALL ADJACENT TRANSITIONS TO BE ACCOMPLISHED BY THE CHANGE OF A SINGLE DIGIT ONLY $ELTA 
 A compromise must generally be  made between these conllicting requirements. A target at long range has low angular rates and  a low signal-to-noise ratio. A narrow tracking bandwidth is indicated in such a case to increase  sensitivity and yet follow the target with minimum lag. 
 Rayleigh region approximations may be derived by expanding the wave equation (11.5) in a power series of the wavenumber k.27 The expansion is quasi-static for small wavenumbers (long wavelengths compared with typical body dimensions), and higher-order terms become progressively more difficult to obtain. The RCS pattern of a Rayleigh scatterer is very broad, especially if the object has similar transverse and longitudinal dimensions. The magnitude of the echo is proportional to the square of the volume of the object and varies as the fourth power of the frequency of the incident wave.28 Because the method of moments . 
 F.: The Effect of the Aperture Illumination on the Circular Aperture Antenna Pattern  Characteristics, 1\1 icro\\'al'e J ., vol. 8, pp. 79-84, August, 1965. 
 TIVELY INDEPENDENT OF WIND SPEED AND FREQUENCY 4HE DEFINITION OF  R   IN (& RADAR  IS COMPLICATED BY PROBLEMS IN PROPERLY DEFINING ANTENNA GAINS FOR GROUND 
 Electron. Conf. NAECON 1986 , May 19–23, 1986,   pp. 
 POWER TRANSMITTERS AND PHYSICALLY LARGE ANTENNAS AT THE LOWER FREQUENCIES /N THE OTHER HAND  AT THE HIGHER RADAR FREQUENCIES  IT IS EASIER TO ACHIEVE ACCURATE MEASUREMENTS OF RANGE AND LOCATION BECAUSE THE HIGHER FREQUENCIES PROVIDE WIDER BANDWIDTH WHICH DETERMINES RANGE ACCURACY AND RANGE RESOLUTION  AS WELL AS NARROWER BEAM ANTENNAS FOR A GIVEN PHYSICAL SIZE ANTENNA WHICH DETERMINES ANGLE ACCURACY AND ANGLE RESOLU 
 Thefrequency spectrum ofafinite-duration sinewavehasashapeoftheform [sinrr(f-.I~)c5]/rr(f -10)'where10andc5arethefrequency andduration ofthe sine wave, respectively, and1isthefrequency variable overwhichthespectrum isplotted(Fig.3.5h). Practical receivers canonlyapproximate thischaracteristic. (Notethatthisisthesameasthe spectrum ofapulseofsinewave,theonlydifference beingtherelativevalueoftheduration c5.) Inmanyinstances, theechoisnotapuresinewaveoffiniteduration butisperturbed by fluctuations incrosssection, targetaccelerations, scanning fluctuations, etc.,whichtendto. 
 According to Figure 7, the ionospheric correlation length dramatically declines with the increase of spectral index. The correlation length of sliding spotlight mode is less than stripmap mode, which means the sliding spotlight mode is more sensitive to the scintillation effect. The IPL of the space-borne P-band sliding spotlight SAR system is 142.03 km ( IPL=VsatTa,Vsatis the platform velocity obtained from the orbit roots). 
 (9.15) the overall noise figure of a radar receiver with a noise figure F, preceded  by RF circuitry with a loss hF, is equal to F,hF. In a radar the overall loss hF due to the  352INTRODUCTION TORADAR SYSTEMS higherfrequencies. Thetransistor isgenerally usedinamultistage configuration witha typicalgainperstagedecreasing frOml2dB atVHFto6dBatKIIband.10IntheGaAsFET, thethermal noisecontribution isgreaterthantheshotnoise.Cooling thedevicewilltherefore improve thenoisefigure.2I Thetunnel-diode amplifier hasbeenconsidered inthepastasalow-noise front-end, with noisefiguresfrom4to7dBovertherange2to25GHz.IOIthasbeensupplanted bythe improvements madeinthetransistor amplifier. 
 It could have been much longer and could have included multiple exam - ples from each of the other chapters in this book, but this listing is sufficient to indicate  the type of advances that have been important for improved radar capabilities. 1.9 APPLICATIONS OF RADAR Military Applications.  Radar was invented in the 1930s because of the need  for defense against heavy military bomber aircraft. 
 7,  pp. 293-328. 1958. 
 proper ratio between the azimuth and elevation beamwidths. Many long-range ground-based  search radars use a fan-beam pattern narrow in azimuth and broad in elevation.  The rate at which a fan-beam antenna may be scanned is a compromise between the rate  at whicll target-position information is desired (data rate) and the ability to detect weak  targets (probability of detection). 
 For reflection and transmission cavities, useful equations adapted from Grauling and Healy11 are given below. For a matched reflection cavity, Z-I^ JbQ = №QL ZH-I 1 + JbQ 1 + j2bQL where F = reflection coefficient S = (f-/0)//o Q = unloaded Q of cavity QL = loaded Q of cavity Z = normalized impedance looking into cavity . The transmission cavity has similar characteristics except that both the carrier (Vc) and sidebands (Ksb) are passed. 
 The aircraft included Liberator, Wellington, Sunderland, Catalina, Barracuda, Beau ﬁghter, Mosquito, Anson, Warwick, Spit ﬁre, Walrus, Sea Otter, Hurricane, Fortress, Halifax and Hudson [ 1,3]. Coastal Command ’s principle roles were Anti-Submarine Warfare and Anti Shipping operations, but there were also squadrons specialising in Air-SeaRescue, Meteorological Flights and Photo-Reconnaissance. 1.3 Airborne radar development and trials organisations To understand the development and contribution of the early ASV radars, it isnecessary not only to understand how they worked but also to critically assess how well they worked. 
    # " !' '(  ! #  !' '(  ! # .   05,3% $/00,%2 2!$!2   {° 2ANGE 'ATING  2ANGE GATING DIVIDES THE TIME BETWEEN TRANSMIT PULSES INTO MUL 
 2.13). Reduction ofthe blind region below this lower edge bylocating thesetonhigh terrain maybe advanta- geous where the coverage islargely over water, but foroverland surveil- lance this recourse isseverely limited because ofpermanent echoes, which can mask out allreturn inregions where the radar beam isinter- cepted byland surfaces. 4.5 2: z .30 z z25 . 
 0.4::.1:. !.1;--:------~--- ..I; I!---LL.i.-L 0.2 .-l-a: ...:. ii''c'II"i"'".,.,.I: :::;0'g60'· ..·.,I'651 5_02';;:;~;ljliiHII'A'" ;:;.~1!¥¥-''''l. 
 Reflecting facets deeper in the waves then gradually con­ tribute, accompanied by an increase in the illuminated  area within a range resolution cell, until a point is  reached where the surface of constant range reaches the  wave troughs. Beyond that point, the illuminated area  within a range resolution cell remains essentially con­ stant. The signal amplitude would also remain constant,  except for the antenna pattern attenuation that imparts  an exponential decay in amplitude. 
 9.2] ROUND ANI) CCI’T PARABOLOID ANTENNAS 273 Fxm9.4.—The angufar distribution ofenergy from atwo-dipole feedincorrectly designed.. 274 ANTENNAS, SCANNERS, AND STABILIZA TIO.V [SEC. 9.3 tally, the beamwidth can bemeasured byexploring the intensity ofthe radiation totheright and left ofthecenter ofthebeam or,alternatively, above and below the center ofthe beam. 
 The difference in the phase of the voltages coupled from an adjacent pair of elements  to element 00 ( e00 in Figure 13.13) is related to the scan angle by  2 2 210 0π λπ λπ λs s s+ = + sin ( sin ) q q  The couplings will be in phase when ∆y = 2p  or when  s λ=+1 10 sinq  This is seen to be exactly the same conditions as previously determined for the emer - gence of a grating lobe into real space. Therefore, it may be expected that when a grat - ing lobe is about to emerge into real space, the coupled voltages tend to add in phase  and cause a large mismatch. Array Simulators. 
 (h)horizontal polarilation. TwocurvesareshownforPhoenix: oneisforasamplesizeof1000and corresponds tothedowntown area.theotherisforasamplesizeof25.000whichrepresents alargerarea andincludes asm<lllerdensityofpointtargetsthanthesmallersample.(FromDaley.etal.37). 4% INTRODUCTION TO RADAR SYSTEMS  effectiveness of interclutter visibility has been exploited in MTI radar and in non-MTI radar  with log-FTC receiver characteristics. 
   PP n  *ANUARY    ' 7 %WELL AND 3 0 :EHNER  h"ISTATIC RADAR CROSS SECTION OF SHIP TARGETS v  )%%% * /CEAN %NG    VOL /% 
 02& 0ULSE 2EPETITION &REQUENCY  RADAR  AVOIDS THE INFLUENCE OF CLOSE 
 G. Bath The Johns Hopkins University Applied Physics Laboratory (CHAPTER 7) Michael T. Borkowski Raytheon Company (CHAPTER 11) Jeffrey O. 
 TO 
 VALUED SAMPLES ARE FIRST CLOCKED INTO THE &)2 FILTER SHIFT REGISTER  FILLING THE SHIFT REGISTER WITH ZEROES AND FORCING THE FILTER OUTPUT TO BE ZERO 7HEN THE SAMPLE WITH A VALUE OF hv IS CLOCKED INTO THE FILTER  THE FILTER OUTPUT PRODUCES THE FIRST COEFFICIENT   A    SINCE THE OTHER SAMPLES IN THE FILTER ARE STILL  ZERO /N THE NEXT CLOCK  THE  hv MOVES TO  THE SECOND TAP OF THE SHIFT REGISTER  AND A hv IS CLOCKED INTO THE FIRST TAP  FORCING THE FILTER OUTPUT TO PRODUCE THE SECOND FILTER COEFFICIENT  A  /N SUCCESSIVE CLOCKS  THE hv  PROPAGATES THROUGH THE SHIFT REGISTER  WHILE ZEROES ARE CLOCKED INTO THE SHIFT REGISTER INPUT  PRODUCING ALL OF THE FILTER COEFFICIENTS ON THE OUTPUT IN SEQUENCE 4HE &)2 FILTER USES FEED 
 50. D. D. 
 PLANE DATA IS OFTEN USED IN SCATTER JAMMING HOT CLUTTER  CALCULATIONS 4HE BISTATIC ANGLE IS CALCULATED FROM THE ANGLES IN &IGURE  BY THE USE OF  DIRECTION COSINES   A   COS 
 Calibration can be divided into two categories: factory calibration and in-the-field  calibration.107 Factory calibration is only performed once, usually at the antenna test  range of the phased array manufacturer. In-the-field calibration is performed at regu - lar intervals throughout the life of the array, after it has been deployed. The antenna  measurements required for factory calibration can be made in three different types  of antenna ranges: near field, compact, or far field. 
 Stojanovic et al. use the sub-aperture method to extract the curve of the radar cross section (RCS) amplitude of pixels versus aspect angles using single-polarization CSAR data [ 15]. The curve intuitively shows whether a target is anisotropic or isotropic. 
 If the notch were set wide enough to remove the birds, it might be wider  than necessary for ordinary clutter and desired targets might be removed. Since the appear­ ance of birds varies with the time of day and the season, it is important that the width of the  notch be controlled according to the local conditfons .  . 
 This pioneering work led the way toward the use of networks of doppler radars for studies of individual clouds and larger-scale cloud systems. For the first time, it became possible to examine the three-dimensional structure of vector air motion in precipitation. Figure 23.7 illustrates an air motion field obtained by multiple-doppler radar observations in an individual convective storm cell. 
 F. Earl and B. D. 
 DIGITAL CONVERTER !$#   DIGITAL DOWN CONVERSION $$#  TO A COMPLEX ENVELOPE SEQUENCE  TIME 
 J.: Arrival Time Estimation by Adaptive Thresholding, IEEE Tram., vol. AES-10, pp.  178-184, March, 1974. 
 ANGLE DEPENDENCE  OF 8 
 FREQUENCY PORTION !S LONG AS THE TWO PORTIONS OF THE SAMPLED SIGNAL DONT OVERLAP  THE SIGNAL IS NOT ALIASED 4HE FULL SAMPLED 
 Middleton, D.: On New Classes of Matched Filters and Generalizations of the Matched Filter  Concept, pp. 349-360.  5. 
 I.- ~0.1 cxuo L..­l.- E ::30' Co '"E I.- .~0.01-E Clla::/ I IL.Receiver noise (monopulse) '<4.''-- Receiver noise (conicalscanI 10 100 Relativeradarrange1,000 Figure5.14Relative contributions toangletracking errorduetoamplitude fluctuations, anglefluctua­ tions,receivernoise,andservonoiseasafunction ofrange.(A)Composite errorforaconical-scan or sequential-Iobing radar;(8)composite errorformonopulse.. scatterers will change and a new resultant is obtained as well as a new angular measurement.  Measurements are independent if tlie frequency is changed by an amountJ6  where c = velocity of propagation arid D = target depth. 
 - VERSUS -)' 
 The effective aperture width )' for several aperture distributions which can be computed  analytically arc given below:  l'araholic distrih11tio11  For L\ = 0  For L\ = 0.5  Fori'1 = 1.0  Cosine distribution  Triangular distribution 4(1 -L\)x2  A (x) = I -· · ·· jjI ---- y2 = 0.863D2  y2 = l.88D2  y2 = 3.287D2  7tX A(x) = cos 7S  y2 = l.286D2  2 A(x)= I -jj lxl  y2 = 0.986D2 Ix I Ix I D <-· 2  D <-2 (11.43)  ( 11.44)  (11.45)  Inverse probability, likelihood ratio, and accuracy. The method of inverse probability as  described by Woodward5 can be used as a basis for determining the theoretical accuracies  :ssociated with radar measurements. The likelihood function also can be used for deriving  measurement accuracy.9 Both methods result in accuracy expressions like that of Eq. 
 17. M. J. 
 17, issue 5, pp. 10–12, May 2002. 20. 
 and C. M. Russell:" Ultra High Frequency Propagation," John Wiley & Sons, Inc .. 
 Even with alinear CRT grid characteristic, the problem ofnarrow dynamic range would beaserious one. General methods ofattacking itwill now bedescribed. 13.21. 
 GAUSSIANSPECTRRUM 
 Lipson: GCA Radars: Their History and State of Development,  Proc. IEEE, vol. 62, pp. 
 5.17~) will result which may be used to reposition the center of  the gates.55 The magnitude of the error signal is a measure of the difference between the center  of the pulse and the center of the gates. The sign of the error signal determines the direction in  176INTRODUCTION TORADAR SYSTEMS Thenormalmonopulse radarreceiver usesonlythein-pbase (ortheout-of-phase) com­ ponentofthedifference signal.Whenthereisamullipath signalpresentalongwiththedirect signal,aquadrature component ofthedifference signalexists.Thein-phase andthequadra­ turecomponents oftheerrorsignaldefineacomplex angke.noJ:-signal. Inthecomfllex plane. 
 A total of four hybrid junctions generate the  sum channel, the azimuth difference channel, and the elevation difference channel. Three  separate mixers and IF amplifiers are shown, one for each channel. All three mixers operate  from a single local oscillator in order to maintain the phase relationships between the three  channels. 
 The output ofthe mixer would be lower figure shows thedifference, orbeat, periodic with periodicity corre- between ‘ransmi%d and. ‘e’eived ‘r!-quencies, asafunct]on oftime. ThehorL- sponding tothe modulating fre- zontal axisintheupper figure corresponds to quency. 
 From the Table 1,w ec a n see that the two devices observed the same ionosphere at the same time. T able 1. Corresponding observing times and positions of three groups of data. 
 Crispin, J. W., Jr., et al.: "A Theoretical Method for the Calculation of Radar Cross Section of Aircraft and Missiles," University of Michigan, Radiation Lab. Rept. 
 . £°{Ó  2!$!2 (!.$"//+   2 * $OVIAK AND $ 3 :RNIC `  $OPPLER 2ADAR AND 7EATHER /BSERVATIONS  ND %D  -INEOLA  .9  $OVER 0UBLICATIONS    6 . "RINGI AND 6 #HANDRASEKAR   0OLARIMETRIC  $OPPLER  7EATHER  2ADAR  0RINCIPLES  AND  !PPLICATIONS  #AMBRIDGE  5+ #AMBRIDGE 5NIV 0RESS    2 - ,HERMITTE   #ENTIMETER  -ILLIMETER 7AVELENGTH 2ADARS IN -ETEOROLOGY   -IAMI ,HERMITTE  0UBLICATIONS    2 % 2INEHART  2ADAR FOR -ETEOROLOGISTS  TH %D  #OLUMBIA  -/ 2INEHART 0UBLICATIONS      h3PECIAL ISSUE ON RADAR METEOROLOGY v )%%% 4RANS 'EOSCI %LECTRON  '% 
 Quite often the  ordinate of a radiation pattern is given as the gain normalized to unity and called relative gain.  Unfortunately the term gain is used to denote both the peak gain and the gain as a function of  angle. Confusion as to which meaning is correct can usually be resolved from the context. 
 White, one of the reviewers of the revised manuscript of  this book.  398INTRODUCTION TORADAR SYSTEMS 77.Finn,H.M.,andR.S.Johnson: Adaptive Detection ModewithThreshold ControlasaFunction of Spatially Sampled Clutter-Level Estimates, RCARev.,vol.29,pp.414-464, September, 1968. 78.Dillard,G.M.,andC.E.Antoniak: APractical Distribution-Free Detection Procedure forMultiple­ Range-Bin Radars,IEEETrans.,vol.AES-6,pp.629-635, November, 1970. 
 The CRT display from this type of  MTI radar appears." cleaner" than the display from a normal MTI radar, not only because of  better clutter rejection, but also because the threshold device eliminates many of the unwanted  false alarms due to noise. The frequency-response characteristic of the range-gated MTl might  appear as in Fig. 4.20. 
 FIELD PROBE POSITION MEASUREMENT SYSTEM v  -ICROWAVE *   PP n  /CTOBER   2 * -AILLOUX  #HAPTER  IN  !NTENNA %NGINEERING (ANDBOOK   2 # *OHNSON AND ( *ASIK EDS    ND ED  .EW 9ORK -C'RAW 
 IfQ.isthe charge onthecondenser, aslong as theenergy intheinductance attime Tequals that attime O, ~T v. i(it=VSQC =+CV& o But Q.=CVc. Then T“,(7VC =*Cv; or v.=2V, and the voltage onthe condenser C(orpulse-forming network) will be twice thesupply voltage. 
 Hoekman136) ch16.indd   40 12/19/07   4:56:09 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 Thus, the total number of such samples is approximately the product of the number calculated from Eq. (12.13) and the number of ground cells averaged. Figure 12.17 shows some ex- amples of the effect of the angle of incidence on the number of independent sam- ples for a horizontally traveling scatterometer with a forward-pointed beam. 
 ABLE IN THIS CASE  AT PRECISELY END 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.716x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 15. E. 
 DEPENDENT PATTERN 4HIS IS MULTIPLIED WITH THE ARRAY FACTOR AND ALSO APPLIES FOR THE SUM AND DIFFERENCE PATTERNS 4HE RESULTANT FORM OF THE BEAM PATTERN WILL THUS BE INDEPENDENT OF POLARIZATION 4HEREFORE  THE MONOPULSE OPERA 
 MS PULSE WIDTHS AT DUTY CYCLES UP TO  -ORE THAN   TRANSISTORS HAVE BEEN BUILT INTO MORE THAN   MODULES &UTURE UPGRADES OF THIS DESIGN IN THE "-%73 ARRAYS WILL USE THE MORE POWERFUL AND EFFICIENT 3I ,$-/3 &%4 TECHNOLOGY FOR ENHANCED PERFORMANCE CAPABILITIES !.303 
 2, March 1976, pp. 287–290. 65. 
 SEC. 1621] SPECIAL TESTEQUIPMENT 679 Subclutter Visibility Measurement.—A block diagram ofasubclutter visibility meter suitable formeasuring theinternal performance ofmost MTI systems isshown inFig. 16.37. 
 Acoust. Soc. Am., vol. 
 It was assumed in the analysis of a bandwidth-limited  pulse that a matched filter was employed. If the spectral width of the "rectangular" pulse is  changed, the matched filter must be changed also.  The rms timedelay error for a trapezoidal-shaped pulse of width 2T1 across the top, flat  portion and with rise and fall times of Tz may be shown from Eqs. 
 CESSING TO CLEANLY ISOLATE AND IDENTIFY INDIVIDUAL %- EMITTERS  WILL ENHANCE SITUATION AWARENESS 5SING TECHNIQUES SUCH AS TIME AND FREQUENCY DIFFERENCE OF ARRIVAL WILL IMPROVE SINGLE AND MULTIPLE PLATFORM SPATIAL LOCATION THIS WILL ALLOW %7 TO BE USED TO CUE TARGETING SYSTEMS 2ADAR INTERCEPTION  WHICH IS OF PARTICULAR INTEREST IN THIS SECTION  IS BASED ON THE  RECEPTION AND MEASUREMENTS OF THE SIGNALS TRANSMITTED BY RADAR SYSTEMS WHETHER PULSE OR #ONTINUOUS 7AVE #7  4HE OPERATIONAL SCENARIO IN WHICH %3- SHOULD OPERATE IS  GENERALLY CROWDED WITH PULSED RADAR SIGNALS FIGURES OF   TO  MILLION PULSES PER  SECOND ARE FREQUENTLY QUOTED IN THE LITERATURE  4HE CENTER FREQUENCY  AMPLITUDE  PULSE  WIDTH  TIME OF ARRIVAL 4O!   AND BEARING OF EACH DETECTED PULSE ARE MEASURED  CON 
 Themethodofinverseprobability involves theuseoftheaprioriprobabilities associated witheachofthepossible hypotheses whichcouldexplaintheevent.Theaprioriprobabilities areused,alongwithaknowledge oftheevent,tocompute theaposteriori probabilities. A separate aposteriori probability iscomputed foreachhypothesis. Thathypothesis which resultsinthelargestaposteriori probability isselected asthemostlikelytoexplaintheevent. 
 Most problems offabrication have. 376 THEMAGNETRON ANDTHEPULSER [SEC.10.10 been overcome. Perhaps TiOz, orsome similar material ofhigh dlelectnc constant, will find wide use outside the low-voltage field. 
 WAY  
 Other GPR systems are designed  to be inserted into boreholes to provide images of the intervening rock. Typical GPR  system attributes are given in Table 21.2. Most GPR systems use separate, man-portable, transmit and receive antennas,  which are placed on the surface of the ground and moved in a known pattern over the  surface of the ground or material under investigation, and an image can be generated,  in real time, on a display either in grey scale or in color. 
 SURABLE PRECIPITATION  TO  D":  AND hCLEAR AIRv ECHOES TO  KM WHERE THE %ARTHS CURVATURE PREVENTS SURFACE 
 MTI RADAR  2.656x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 2.12 RADAR SYSTEM STABILITY  REQUIREMENTS System Instabilities.  Not only do the antenna motion and clutter spectrum affect  the improvement factor that is attainable, but system instabilities also place a limit on  MTI performance. These instabilities come from the stalo and coho, from the trans - mitter pulse-to-pulse frequency change if a pulsed oscillator and from pulse-to-pulse FIGURE  2.70 Distribution of I3 and mean of I3 for hard-limited clutter for different numers of scan - ning hits per beamwidth. 
 (Copyright 1974, IEEE; from Ref. 26.)RANK DETECTOR THRESHOLD DIGITALINPUTSR8 CELLSSR7 CELLS RANK (4 BITS) TWO-POLE INTEGRATORINTEGRATEDOUTPUT FIXEDAVERAGEM OUTPUTIS DECISION . the advantage that for essentially stationary environments (e.g., land-based radar against ground clutter), the radar has interclutter visibility—it can see between large clutter returns. 
 18,  No. 11, pp. 47–50, November 1975. 
 CAL MODEL FOR THIS BEHAVIOR  WITH REASONABLE SUCCESS  4HERE ARE SEVERAL VECTOR WIND  RETRIEVAL METHODS IN CURRENT USE  INCLUDING #-/$ 
 Scruton, C., and P. Sachs: Wind Effects on Microwave Reflectors, "Design and Construction  -of Large Steerable Aerials." IICl~E (I,ottclot~) ('or~f: P~chlicntio~t no. 2 1, pp. 
 The inherent dMiculty ofthe problem isdisplayed bythe fact that the GCA really consists ofthree separate radar equipments. One isaPPI setwhich presents ageneral picture oftheairtraffic situation; theother two, which comprise the precision system, have “beavertail” beams narrow respec- tively inazimuth and inelevation. Each ofthese israpidly scanned in itsnarrow dimension, and separate indicators ofthe “stretched PPI” type present the two angular coordinates. 
 OF 
 FILTER OUTPUT 3.2 IS %.. n°{ä  2!$!2 (!.$"//+  !MBIGUITY  &UNCTIONS   n  4HE AUTOCORRELATIONo FUNCTION FOR A TRANSMIT  WAVEFORM WITH COMPLEX ENVELOPE UT  IS DEFINED AS   CT TP UDJFTFU T U T E D TD       
 RANGE RESOLUTION COMPARABLE TO WHAT  WOULD  IN PRINCIPLE  BE ACHIEVED BY A REAL APERTURE  WITH A LENGTH EQUAL TO THE PATH LENGTH SYNTHETIC APERTURE   , 3!   DLL CR 3!yy2 ,$P    SYNTHETIC APERTURE     WHERE $P IS THE SYNTHETIC APERTURE ANGLE  IE  THE ANGLE SUBTENDED BY THE SYNTHETIC  APERTURE AS SEEN FROM THE TARGET AREA 4HE ADDITIONAL FACTOR OF TWO IN THE DENOMINATOR COMPARED WITH %Q   OCCURS BECAUSE OF THE 3!2 PROCESSING AND WILL BE DISCUSSED &OR EXAMPLE  FOR A PATH LENGTH OF  KM  THE CROSSRANGE RESOLUTION FOR THE CASE DISCUSSED ABOVE WOULD BE y  CM  CLEARLY A SUPERB IMPROVEMENT OVER THE REAL 
 Zebker, H. Z., and G. L. 
 2AO LOWER BOUND 4HE RESULTS                              
 Abankoffilters, asinFig.4.23,issometimes calledacoherellt integratio1J filter. Togenerate theNfilterssimultaneously, eachofthetapsofthetransversal filterof Fig.4.11wouldhavetobedivided intoNseparate outputs withseparate weightscorrespond- 1oNT FrequencyFigure4.23MTIdoppler filter bankresulting fromtheprocessing ofN=8pulseswiththeweightsof Eq.(4.13),yielding Iheresponse of Eq.(4.16).FiltersideJobes not shown.. ing to tlie k = 0 to N - 1 weighting as given by Eq. 
 74  Ci108S 1-3AP.  77. Dyer. 
 Therefore the  majority of the cooling required in the klystron is at the collector. Power is extracted from  the output cavity and delivered to the load by a coupling loop (as shown in Fig. 6.9) for  low-power tubes, or by waveguide in high-power tubes. 
 UNIT AT THE TOP OF THE DUCT IS THE SAME AS THE  - 
 TYPE TRANSMITTERS  ENERGY MANAGEMENT IS STILL CRUCIAL %ACH DC POWER SUPPLY MUST HAVE A CAPACITOR BANK LARGE ENOUGH TO SUPPLY THE ENERGY DRAWN BY ITS SOLID 
 NOISE RATIO 3.2  )N ORDER TO PRESERVE THIS 3.2 GROWTH  THE NUMBER OF BITS USED TO REPRESENT THE FILTER OUTPUT MIGHT NEED TO INCREASE )F THE FILTER REDUCES THE BAND 
 It may be noted that detection performance is not very sensitive to false alarm rate and a reduction in Pfato, say, 10−5would reduce sensitivity by about 0.8 dB following 18 pulses integrated. The curves in the ﬁgures here model the statistics of the clutter and noise and the effects of pulse-to-pulse integration more accurately than the simple ﬁgures of merit discussed above. They can be used to compare the noise-limited performance of the three radars. 
 One type iscaused byanode currents sohigh that they exceed theconditions foroscillation and cause transition into astate ofnonoscillation orinto another mode ofoscillation. The second type arises from afailure oftheoscillations inthedesired mode to build uprapidly enough with respect tothevoltage riseatthestart ofthe pulse. The first type isencountered usually inlower-power c-w magne- ~ r/-Pulserloadcurve ,\ \‘\ I:,)(*’’”’”IIV-1curvefor oscillations I ‘-(desiredmode) 1 ,1 ‘bPulsecurrent _ F1~. 
 -ÊÊ ",Ê,"1  Ê, 
 Figure 25.30  shows a block diagram of a direct-form digital FIR  filter. The input sample feeds a shift register, where  each block labeled t  indicates a one-sample delay  in the shift register. The input sample and the output  of each stage of the shift register are multiplied by  unique coefficients, and the multiplier outputs are  summed to produce the filtered output. 
 LOOK DATA TAKE  SETTING THE BURST REP 
 Inprototyping each installation the minimum protrusion allowable from the standpoint ofthediffraction oftheradia- tion must bedetermined bymeasurements oftheantenna pattern made FIQ.9.37.—The raydiagram shows thatfan-beam antenna may beinstalled partly inside thefuselage. with the antenna installed inamockup. 1Such measurements have shown that some circularly scanning fan-beam antennas may beso installed that nearly half their height isabove thekeel line oftheairplane, and this conclusion has been confirmed inobservation oftheindicator in flight. 
 FERENCE DISPLAYED TO OPERATORS  4HE DISADVANTAGES OF PULSE COMPRESSION ARE RELATED  TO THE LONG DURATION OF THE CODED PULSE  WHICH GIVES MORE TIME FOR THE %#- EQUIP 
 The three- dimensional RCS of a truncated two- dimensional structure may be found from the approximate relationship 2€2a2D sin (M sin T) 2° = — Ws^- (1L3) where € is the length of the truncated struc- ture, (T20 is its two-dimensional scattering width (obtained for the infinite structure), and T is the tilt angle of the segment measured from broadside incidence. This approximation assumes that the amplitudes of the fields in- duced on the three-dimensional body are iden- tically those induced on the corresponding two-dimensional structure and that the tilt an- gle influences only the phase of the surface fields induced on the body. The expression should not be used for large tilt angles, for which the amplitudes obtained from the two- dimensional solution no longer apply to the three-dimensional problem. 
 Hansen and J. R. Ward, “Detection performance of the cell average log/CFAR receiver,”  IEEE Trans ., vol. 
 NOISE AMPLIFIER &OR MANY RADAR APPLICATIONS WHERE THE LIMITATION TO DETECTION IS THE UNWANTED RADAR ECHOES FROM THE ENVIRONMENT CALLED  CLUTTER   THE RECEIVER NEEDS TO  HAVE A LARGE ENOUGH DYNAMIC RANGE SO AS TO AVOID HAVING THE CLUTTER ECHOES ADVERSELY AFFECT DETECTION OF WANTED MOVING TARGETS BY CAUSING THE RECEIVER TO SATURATE 4HE DYNAMIC RANGE OF A RECEIVER  USUALLY  EXPRESSED IN DECIBELS  IS DEFINED  AS THE RATIO OF  THE MAXIMUM TO THE MINIMUM SIGNAL INPUT POWER LEVELS OVER WHICH THE RECEIVER CAN  OPERATE WITH SOME SPECIFIED PERFORMANCE 4HE MAXIMUM SIGNAL LEVEL MIGHT BE SET BY THE NONLINEAR EFFECTS OF THE RECEIVER RESPONSE THAT CAN BE TOLERATED FOR EXAMPLE  THE SIGNAL POWER AT WHICH THE RECEIVER BEGINS TO SATURATE   AND THE MINIMUM SIGNAL MIGHT BE THE MINIMUM  DETECTABLE SIGNAL 4HE  SIGNAL PROCESSOR  WHICH IS OFTEN IN THE  )& PORTION OF THE RECEIVER  MIGHT BE DESCRIBED AS BEING THE PART OF THE RECEIVER THAT SEPARATES THE DESIRED SIGNAL FROM THE UNDESIRED SIGNALS THAT CAN DEGRADE THE DETEC 
 E. Carbone, M. Carpenter, and C. 
 PLIFY PROCESSING AND COMPENSATE FOR AIRCRAFT MANEUVERS 4HE AIRCRAFT MAY TRAVEL  FT  DURING THE GATHERING TIME 4HERE IS CONSIDERABLE TRANSPORT DELAY IN MOST 3!2 AND $"3 PROCESSING AS A RESULT  PROCESSED RETURNS MUST BE RECTIFIED IE  COMPENSATED FOR GEOMETRIC DISTORTION   MOTION COMPENSATED  AND MAPPED INTO THE PROPER SPACE ANGLE AND RANGE POSITION 3INCE $"3 USUALLY MAPS A LARGE AREA TO PROVIDE OVERALL GROUND SITUATIONAL AWARENESS  THE TOTAL RANGE COVERAGE IS OFTEN COVERED IN MULTIPLE ELEVATION BEAMS AND RANGE SWATHS 4HIS IS TRANSPARENT TO THE OPERATOR BUT REQUIRES DIFFERENT 02&S  PULSEWIDTHS  FILTER SHAPES  AND DWELL TIMES&)'52%  $"3 PROCESSING ADAPTED COURTESY 3CI4ECH 0UBLISHING  . 
 , vol. 81, pp. 501–518, AMS, Boston, 2000. 
 TRACK SURFACE SLOPE TOLER 
 RATED INTO TWO CATEGORIES RECIPROCAL AND NONRECIPROCAL 4HE RECIPROCAL PHASE SHIFTER  IS NOT DIRECTIONALLY SENSITIVE 4HAT IS  THE PHASE SHIFT IN ONE DIRECTION EG  TRANSMIT  IS THE SAME AS THE PHASE SHIFT IN THE OPPOSITE DIRECTION EG  RECEIVE  4HEREFORE  IF RECIPROCAL PHASE SHIFTERS ARE USED  IT IS NOT NECESSARY TO SWITCH PHASE STATES BETWEEN TRANSMIT AND RECEIVE 7ITH A NONRECIPROCAL PHASE SHIFTER  IT IS NECESSARY TO SWITCH THE PHASE SHIFTER IE  CHANGE PHASE STATE  BETWEEN TRANSMIT AND RECEIVE 4YPICALLY  IT TAKES A FEW MICROSECONDS TO SWITCH NONRECIPROCAL FERRITE PHASE SHIFTERS $URING THIS TIME  THE RADAR IS UNABLE TO DETECT TARGETS &OR LOW PULSE REPETITION FREQUENCY 02&  RADARS ;EG   TO  PULSES PER SECOND PPS =  THIS MAY NOT CAUSE A PROBLEM &OR EXAMPLE  IF THE 02& IS  PPS OR (Z   THE TIME BETWEEN PULSES IS   MS )F THE SWITCHING TIME FOR  THE PHASE SHIFTER IS   MS  ONLY  OF THE TIME IS WASTED AND LESS THAN  NMI OF MINI 
 Asthefrequency decreases (increasing wavelength), Fig.12.7indicates thatmoreandmoreenergypropagates beyondthegeometrical horizon. However, thefieldstrength at,andjustwithin,thegeometrical horizondecreases withdecreas­ ingfrequency. Itisconcluded thatiflow-altitude radarcoverage isdesiredbeyondthegeometrical horizon inthediffraction region,thefrequency shouldbeaslowaspossible.If,ontheother hand,low-altitude coverage istobeoptimized withintheinterference regionandifthereisno concern forcoverage beyondthehorizon, theradarfrequency shouldbeashighaspossible. 
 AttheFCC thefollowing steps take place: 1.The filter officer must determine whether theplot isacontinuation ofanoldtrack orthebeginning ofanew one. 2.The track isreidentified, ifpossible, from the fuller intelligence information available atthe FCC. 3.Plots reported from more then one radar station must berecog- nized asbelonging either tothe same track ortodifferent tracks. 
 NOISE RATIO IS REDUCED 4HE FILTER MISMATCH LOSS IS THE AMOUNT BY WHICH THE PEAK 
 ING UNAMBIGUOUS RANGE FOR UNAMBIGUOUS VELOCITY &OR STANDARD CONSTANT 02& RADARS    
 In one simulation of the technique it was found that tracking over a  smooth surface can be improved by at least a factor of two, but over rough surfaces the  improvement was marginaL6'  Thus there exist a number of possible techniques for reducing the angle errors found when  tracking a target at low angle. Some of these require considerable modification to the conven-  tional tracking radar but others require only modification in the processing of the angle-error  signals. It has been said that these various techniques can avoid the large errors encountered  by conventional trackers when the elevation angle is between 0.25 and 1.0 beamwidth. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.60  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 Adaptive beamforming can be implemented by using auxiliary receivers in a side-   lobe cancellation system or by using digital beamforming. 
 The mechanical and electrical superiority ofa solid piece ofmetal asasupport and insulator isobvious, and at10cm thelength ofthestub (about 1in.)issuch astomake theprojection short and unobtrusive. Obviously aquarter-wave stub can have thedesired property atonly onefrequency. Deviations ofonly 1to2percent infrequency cause the stub tohave areactance that pre- sents an appreciable mismatch. 
  
 Following this treatment, an analysis of the signal-to-noise-ratio characteristics of a synthetic antenna compression radar are analyzed. Detailed Resolution Analysis. The analysis will be carried out in terms of an ambiguity function whose properties indicate both the azimuth and the range resolution of the system. 
 DOPPLER PLANE WHERE 9US  FD  y  , 
 Gerlach and M. J. Steiner, “An adaptive matched filter that compensates for I, Q mismatch  errors,” IEEE Trans ., vol. 
 SEC.17.8]PULSE METHOD FORRELAYING SINEANDCOSINE 705 The resulting pulses aremixed with themodulator pulse and coded before being combined with thevideo signals preparatory totransmission. Atthe receiving station, the pulses are decoded and sorted. Each ofthepulse pairs (basic-plus-sine and sine-plus-cosine) isfedtoanauto- matic range-tracking circuit which develops the required voltage as indicated inFig. 
 144 147. January, 1956.  28. 
 THE TASK AHEAD 131  immediately following the War there were differences  between British and American marine methods, but the  authorities in this country have worked hard to develop  simple navigational ideas which have been given to all  seagoing nations, and which may become international  marine standards. This would be no more than poetic  justice, for radar was so pre-eminently a British develop-  ment, and we gave our allies in war the full use of our  scientific research.  It is appropriate to mention that maritime navigation  can hardly fail to benefit from Admiralty centimetric  research during the war years: the greatest triumph of  our surface gunnery was in the famous wartime Scharn-  horst action, the first major naval engagement carried  out entirely by radar. 
 Thenamessimultaneous lobingandmonopulse areusedtodescribe thosetracking techniques whichderiveangle-error information onthebasisofasinglepulse. Anexample ofasimultaneous-Iobing technique isamplitude-comparison motlopll/se, or moresimply,monopulse. Inthistechnique theRFsignalsreceived fromtwooffsetantenna beamsarecombined sothatboththesumandthedifference signalsareobtained simulta­ neously. 
    PP n  3EPTEMBER     $ * -C,AUGHLIN  % "OLTNIEW  2 3 2AGHAVAN  AND - * 3OWA  h#ROSS 
 W. Shrader34 © IEEE 1968 )0.0030102030405010LOG(I)60708090100 Relative Cl utter Spectral Width - σfTσ/L = 0 dB σ/L = 10 dB σ/L = 20 dBNo Limit Hard Limitσ/L = 30 dB 0.05 0.04 0.03 0.02 0.01 0.007 0.005N = 20 N = 10 N = 5 N = 40 N = 80 ch02.indd   63 12/20/07   1:45:20 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The  most common cause of a power amplifier introducing phase changes is ripple on the  high-voltage power supply. Other causes of phase instability include ac voltage on a  transmitter tube filament and uneven power supply loading, such as that caused by  pulse-to-pulse stagger. In the pulsed oscillator system, shown in Figure 2.74, pulse-to-pulse frequency  changes result in phase run-out during the transmitted pulse. 
 AZ = 0, and fi2 small. For  :I quanti7ed pliase sliifter consisting of B bits, the phase error 5 is described by a uniforni  probability density function extending over an interval &7~/2~. From Sec 2.4 the mean square  pliac error for tlie unifortii probability density function is 6' = ~'/3(2~'). 
 (3.17), with L\J substituted in place of fo. (3 .20a)  (3.20h)  (3.21)  (3.22)  The two-frequency CW technique for measuring range was described as using the dopplcr  frequency shift. When the doppler frequency is zero, as with a stationary target, it is also  possible, in principle, to extract the phase difference. 
 BANDWIDTH PRODUCT SIGNALS  THE ELEVATION ANGLE CONSTRAINT IMPLIES THAT CORRELATION OF THE PAIR OF RETURN SIGNALS IS MAINTAINED FOR ORBITAL SEPARATIONS ON THE ORDER OF A KILOMETER &OR ABSOLUTE ELEVATION MAPS TO BE DERIVED  HOWEVER  PRECISE KNOWLEDGE TO THE LEVEL OF ONE METER IS REQUIRED OF THE SPATIAL SEPARATION BETWEEN OBSERVATION TRACKS 4EMPORAL COHERENCE APPLIES PRIMARILY TO THE SCENE )N ORDER FOR THE TWO SIGNALS TO  ACT AS AN INTERFEROMETRIC PAIR  THEIR RESPECTIVE PHASE STRUCTURES MUST BE RELATIVELY STABLE OVER THE TIME INTERVAL BETWEEN SATELLITE OBSERVATIONS )N SHORT  THERE MUST EXIST MUTUAL COHERENCE BETWEEN THE TWO SCATTERING  SIGNALS  EVEN THOUGH THEY ARE OBSERVED AT DIFFER 
 As with most digital technology, it is possible to achieve  greater stability, repeatability, and precision with digital processing than with analog delay­ line cancelers. Thus the reliability is better. No special temperature control is required, and it  can be packaged in convenient size. 
 In Type B what we see is not a V-shaped blip, but a  spot of light which is brighter than the lines drawn out  for the rest of the trace, and this brightness is achieved  by applying the signal not to X or Y plates, but, usually,  cd dieathe  \ tis  wlll  diatutbatiaes,  —  TYPE B DISPLAY  The spot moves upward from x toy, retraces and starts upward at z again, and so on. This is suggested in black lines in (a). (6) and (c) are specimen plots, the first showing a target 45° to the left of the line ahead and 124 miles away, the second showing a target 30° to the right of the line ahead and 40 miles away. 
 A modified CP-2 monostatic weather radar transmits and receives on a narrow beam antenna, while  one or more bistatic receive sites 10–20 km from the CP-2 receive bistatically scattered energy from the  same illuminated weather volume over a broad antenna beam. A transmit/receive tube is used to protect the  receiver, just as in a monostatic radar. All generated frequencies are locked to the master 10-MHz VCXO,  which is, in turn, locked to GPS timing signals. 
 10.4. Asstated there, the requirements ofany system usually make necessary some sort ofcom-. SEC. 
 SVC, as described in Section 2.16, is used when it is necessary to  distinguish very low RCS targets from low velocity clutter, such as birds, insects, and  sea. Somewhat lower PRFs can be used than those used for technique 5 because the  FIGURE  2.99 Two-beam antenna ch02.indd   99 12/20/07   1:52:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Kelleher and H. P. Coleman, “Off-axis characteristics of the paraboloidal reflector,” Naval  Res. 
 This value is lower than ones derived by other  authors.4,5 However, it agrees with more exact analysis of antenna radiation patterns  and experimental data analyzed by F. Staudaher. A more exact value of the parameter spm may be obtained by matching a two-way  power pattern of interest with the gaussian approximation at a specific point on the pat - tern, determining the standard deviation of q  by using statistical techniques or fitting  ch03.indd   9 12/15/07   6:02:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 APPROVED SYSTEMS  SUCH AS BEAMWIDTHS AND GAIN  BUT THESE OBVIOUSLY NEED TO BE COM 
 Es describes the statistical range  of variation of sporadic-E as M (median), L (lower decile), and U (upper decile)  critical frequencies, in megahertz. ch20.indd   56 12/20/07   1:17:00 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 7 th Int. Ionospheric Effects Symp ., Alexandria, Virginia, pp. 2A5-1–2A5-8,  May 1993. 
 BAND FEED AT THE FOCAL POINT 4HE #ASSEGRAIN SUB 
 OFF MUST BE PERFORMED BETWEEN SYSTEM DYNAMIC RANGE AND NOISE FIGURE $EFINITIONS $YNAMIC 2ANGE REPRESENTS THE RANGE OF SIGNAL STRENGTH OVER  WHICH THE RECEIVER WILL PERFORM AS EXPECTED )T REQUIRES THE SPECIFICATION OF A MINIMUM LEVEL  TYPICALLY THE NOISE FLOOR  THE MAXIMUM LEVEL THAT CAN BE HANDLED WITH SOME ALLOWABLE DEVIATION FROM THE IDEAL RESPONSE  AND THE TYPE OF SIGNAL TO  BE HANDLED 4HESE PARAMETERS ARE DEFINED THROUGH A VARIETY OF CHARACTERISTICS AS  DESCRIBED BELOW -ODERN RADARS SYSTEMS INCREASINGLY RELY SOLELY ON LINEAR RECEIVER CHANNELS FOL 
 Thefeed ~~~>-------%-< ;~ ~Array ;~~~menl--EA-----.--~-- ----------- I I Primary I feed : I I :,r.;---i-- Phase~ shifter >---f?J-< Figure8.22Principle oflensarray.. IIlf: I:! f:('I.RONI('Al.I.Y S'I'f~f:KI:I) PIIASEO ARRAY ANTENNA IN KAI)AR ,309  1 I  Arrny ; I Phase  ~IP~IIP~I~ , ( ] str~fler -> -&---I  >---*- Figure 8.23 Reflectarray.  [nay be placed off-axis to avoid reflections from the back face of the lens, if desired. 
 At low sea-state and wind it is possible to image  an oil spill of less than 400 liters durini the period of spillage.68  13.4 DETECTION OF TARGETS IN SEA CLUTTER  The ability of a radar to detect targets on or above the sea can be limited by sea clutter as well  as by receiver noise. The magnitude and extent of the sea clutter seen by the radar will depend  not only on the sea state and wind, but on the radar height. Radar is used to detect at least  three different classes of targets over the sea: aircraft, ships, and small objects such as buoys. 
 Noiseisunwanted electromagnetic energywhichinterferes with theabilityofthereceivertodetectthewantedsignal.Itmayoriginate withinthereceiveritself, oritmayenterviathereceiving antenna alongwiththedesiredsignal.Iftheradarwereto operateinaperfectly noise-free environment sothatnoexternal sourcesofnoiseaccompanied thedesiredsignal,andifthereceiveritselfweresoperfectthatitdidnotgenerate anyexcess noise,therewouldstillexistanunavoidable component ofnoisegenerated bythethermal motionoftheconduction' electrons intheohmicportions ofthereceiverinputstages.Thisis calledthermalnoise,orJohnson noise,andisdirectlyproportional tothetemperature ofthe ohmicportions ofthecircuitandthereceiverbandwidth.60Theavailable thermal-noise power generated byareceiver' ofbandwidth BII(inhertz)atatemperature T(degrees Kelvin) is equalto Available thermal-noise power=kTBII (2.2) wherek=Boltzmann's constant=1.38x10-23Jjdeg.Ifthetemperature Tistakentobl: 290K,whichcorresponds approximately toroomtemperature (62°F),thefactorkTis 4 x10-21WjHzofbandwidth. Ifthereceivercircuitry wereatsomeothertemperature, thl: thermal-noise powerwouldbecorrespondingly different. Areceiver withareactance inputsuchasaparametric amplifier neednothaveany significant ohmicloss.Thelimitation inthiscaseisthethermalnoiseseenbytheantennii and theohmiclossesinthetransmission line. 
  ASYMPTOTE )T SHOULD BE NOTED THAT MOST OF  THE OCEANOGRAPHERS SPECTRA ARE BASED ON MEASUREMENTS AT RELATIVELY LOW FREQUENCIES AND SO CANNOT BE TAKEN SERIOUSLY AT FREQUENCIES ABOVE ABOUT  (Z .EVERTHELESS  THESE SPECTRAL FORMS ARE OFTEN USED UP TO  (Z OR GREATER IN PREDICTING RADAR CLUTTER UNDER THE "RAGG HYPOTHESIS  #ONVERTING THIS FREQUENCY SPECTRUM INTO AN ISOTROPIC WAVENUMBER SPECTRUM  THROUGH %Q  RESULTS IN A SPECTRUM OF SIMILAR FORM  ONLY WITH A  +  
 390 INTRODUCTION TO RADAR SYSTEMS  Such clutter is characterized by having large "spiky" echoes. Although they may occur in­ frequently, they can be quite large and give undue weight in a conventional integrator. In the  double-threshold detector they contribute the same as any threshold-crossing signal no matter  what their amplitude. 
 TheoutputoftheMTDisahitreportwhichcontains theazimuth, range,andamplitude ofthetargetreturnaswellasthefilternumber andprr.Onaparticular scan,alargeaircraft mighthereported frommorethanonedoppler filter,fromseveralcoherent processing inter­ vals,andfromadjacent rangegates.Asmanyas20hit-reports mightbegenerated byasingle largetarget.43Apostprocessor groupstogether allreportswhichappeartooriginate fromthe sametargetandinterpolates tofindthebestazimuth, range,amplitude, andradialvelocity. Thetargetamplitude anddoppler areusedtoeliminate smallcrosssectionandlow-speed angelechoesbeforethetargetreportsaredelivered totheautomatic tracking circuits. The tracking circuitsalsoeliminate falsehit-reports whichdonotformlogicaltracks.Theoutput oftheautomatic trackeriswhatisdisplayed onthescope.SincetheMTDprocessor eliminates alargeamount oftheclutterandhasalowfalse-detection rate,itsoutputcanbereliably n:motcd vianarrowbandwidth telephonc circuits. 
 STATE DEVICES MUST BE  COMBINED TO PROVIDE THE POWER FOR A RADAR TRANSMITTER  AND THEY ARE EASILY COMBINED IN WAYS THAT DEGRADE GRACEFULLY WHEN INDIVIDUAL UNITS FAIL L 4HE ABILITY TO DEMONSTRATE WIDE BANDWIDTH IS A SIGNIFICANT CHARACTERISTIC OF SOLID 
 TURNING 
 Other contributors to amplifier chain RF leakage problems often include collector seals on linear-beam tubes and cathode stems on CFAs. Successful amplifier chain design therefore requires conscious and careful control of RF leakage. Reliability. 
 549-550  Dieiect ric lenses, 248-250  Diffraction, 156-459  Digital phase shifters, 287 --288  Digital processing:  MTI, 119-125  SAR, 526  Diode burnout, 350 .' Diode phase shifters, 288-291 .-'  Diodes, microwave, 2 17  Directive gain, antenna, 224  1)ispcrsivc dclay lines, 424 426  Displaced PIlase Center Antenna (DPCA).  143 144  I)isplays, 353 359  definitions of. 354 355  Dither tuning, of magnetron. 
 VARYING WEIGHTS AS DESCRIBED BELOW /NE FURTHER ADVANTAGE OF PULSE 
 ÓÓ°n  2!$!2 (!.$"//+  4HE )-/ )NTERNATIONAL #ONVENTION FOR THE 3AFETY OF ,IFE AT 3EA 3/,!3  IS AN  ESTABLISHED AND ACCEPTED SET OF PRINCIPLES AND RULES AIMED AT ENSURING THAT SHIPS MEET  CERTAIN REQUIREMENTS TO ENHANCE BOTH SAFETY AND PROTECTION OF THE ENVIRONMENT 4HE MEMBER GOVERNMENTS FLAG 3TATES  OF )-/ HAVE AGREED THAT 3/,!3 REQUIREMENTS ARE EMBODIED WITHIN THEIR NATIONAL MARITIME LAWS AND REGULATIONS 7ITHIN #HAPTER 6 OF 3/,!3  
 475 13.2 Cathode-ray Tube Screens 479 13.3 TheSelection oftheCathode-ray Tube 483 COormlNAmON WITH THE SCANNER 486 13.4 Angle-data Transmitters 486 13.5 Electromechanical Repeaters .,. 490 BASIC ELECTRICAL CIRCUITS .,. 492 13.6 Amplifiers ........ 
 Aircrafttargetflewoutinrange atanearlyconstant altitude. Thenumbers alongthezeroerrorline,indicatethetracktimeinminutes. (FromLinde.46). 
 3:t Wylie. F. J.: "The Use of Radar at Sea," Hollis and Carter. 
 In cathode-pulsed tubes, the high voltage is removed from the RF tube between pulses, and no in- terference with receiver operation is normally encountered unless there is exces- sive modulator fall time or backswing, which can produce noise rings (Sec. 4.2). With de-operated CFAs or with mod-anode or gridded linear-beam tubes, the high voltage remains on the tube between pulses, and serious noise may be gen- erated if even a small amount of beam current is allowed to flow through the tube. 
 Table 7.4. Reported extent of clutter returns (min –max). Height, ftRange extent of sea returns, min –max, nmi Rough Moderate Slight/Calm ASV Mk. 
 I\. lens focuses the CRT output on a moving strip of film whose rate of  travel is proportional to the speed of the vehicle carrying the radar. The vertical dimension on  the film represents the range and the horizontal dimension represents the cross-range, er  along-trac~coordinate. 
 Digital beamforming offers several advantages over analog beamforming. With an  analog beamformer, usually only one beam is formed at a time. Radars are typically  required to perform multiple functions, such as volume surveillance, target confir - mation, tracking, etc. 
 The results areshown inTable 7“1. TAELE 71.-REPORTING BYFDP’s OFIXTAC, 21OCTOBER TO16NOVEMBER 1944 Station Day averages FDP “C” (Microwave) FDP” A” FDP’’ II”.. Night averages FDP “C” (Microwave) FDP “A” FDP’’B”..Total tracks 1561 2416 828 1249 1805 774Avg. 
 Stacked beams are another example of simultaneous lobing for target elevation-angle estimation. The processing of a pair of beams in the stack consists of an amplitude comparison table lookup. Its fundamental accu- racy can also be placed in the form of Eq. 
 The plate cannow fallfarther only asthepotential ofthefirst grid rises, bydischarge ofCl through R,.The condenser C,acts asafeedback condenser, assuring linearity ofthe tube response sothat the plate falls linearly with the time. When the plate reaches the potential ofthe second grid itno. SEC. 
 Although electromechanical shiftersarenotnowwidelyused,theyaredescribed heretoillustrate thevarietyofdevicesthatmightbeemployed inarrayantennas. Oncoftheearliestandsimplest formsofelectromechanical phaseshifters isatransmis­ sionlinewhoselengthisvariedmechanically, aswithatelescopic section.Thisiscalledaline stretcher. Thetelescoping sectionmightbeintheformofa"U",andthelengthoftheline changed inamanner similartothatofaslidetrombone. 
 € fB=1 2f2+f1 ( );fD=12(f2−f1) (7.15)  A typical FM CW Radar instrument is demonstrated in Figure 7.9.  The frequency modulation  is triangular in form.  The Radar has separate transmitting and receiving antennas. 
 EXCITER UNCORRELATED 34!,/ 33" PHASE NOISE  &2F    RANGE DEPENDENCE FACTOR 2ESIDUE 0OWER AND -4) )MPROVEMENT &ACTOR  3UBSEQUENT STAGES OF THE RECEIVER  AND SIGNAL PROCESSOR HAVE RESPONSES THAT ARE FUNCTIONS OF THE DOPPLER MODULATION FRE 
 93–96, June 1965. 59. P. 
 Thus the design of the radar for maximum performance  will differ from that when receiver thermal noise sets the limit. In addition to satisfying the  needs for an adequate signal-to-noise ratio, there must be adequate signal-to-clutter ratio. 532 INTRODUCTION TO RADAR SYSTEMS  Signal-to-clutter ratio usually can be increased with narrow beamwidths and narrow  pulsewidths. 
 The input and reference signals are of the same  frequency. The output d-c voltage reverses polarity as the phase of the input signal changes  through 180°. The magnitude of the d-c output from the angle-error detector is proportional to  the error, and the sign (polarity) is an indication of the direction of the error. 
 The lower PRF eases the measurement of true range while retaining the high-PRF advantage of a single blind-speed region near zero doppler.NOSE TAILVR - RADAR AIRCRAFT VELOCITY VECTOR V1 - TARGET VELOCITY VECTOR COLLISION COURSE RADARCASE VT/VR ~® 1 ® 0.8 (3) 0.6 0 0.4 CLEARREGIONSIDELOBE CLUTTERREGION . The choice between high and medium PRF involves a number of consider- ations, such as transmitter duty cycle limit, pulse compression availability, signal-processing capability, missile illumination requirements, etc., but often de- pends on the need for all-aspect target detectability. All-aspect coverage requires good performance in tail chase, where the target doppler is in the sidelobe clutter region near the altitude line. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation.  THE PROPAGATION FACTOR, FP, IN THE RADAR EQUATION  26.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 AREPS provides some basic “canned” antenna patterns such as omni, SinX/X, cose - cant-squared, and a generic height-finder. 
 GO PROCESS  AND SO SLICKS WILL TEND TO HAVE RELATIVELY SHARP BOUNDARIES )N OPERATING THE .2, &2 SYSTEM AS A SYNTHETIC APERTURE RADAR TO OBTAIN IMAGES OF THE SLICKS PRODUCED BY OIL SPILLS  'UINARD FOUND THAT THE SLICKS WERE WELL DEFINED  THAT IT TOOK VERY LITTLE OIL TO MAINTAIN A VISIBLE SLICK  THAT VERTICAL POLARIZATION PROVIDED MUCH GREATER CONTRAST THAN DID HORIZONTAL  AND THAT THE SLICKS WERE QUENCHED BY WINDS AND CURRENTS  !LTHOUGH SIGNAL STRENGTH WAS NOT RECORDED IN THIS IMAGING EXPERIMENT  LATER  MEASUREMENTS AT 8 AND , BANDS BY OTHERS INDICATED THAT AT THE HIGHER GRAZING ANGLES  ABOUT   THE CLUTTER REDUCTION PRODUCED BY THE TYPES OF OIL OCCURRING IN  NATURAL  SLICKS WAS RATHER SMALL  ON THE ORDER OF A PERCENT 3INCE SLICKS ARE DISPERSED BY THE WIND AND ASSOCIATED WAVE ACTION AT WIND SPEEDS GREATER THAN ABOUT  KT  THE EFFECT OF NATURAL SLICKS ON CLUTTER MAY NOT BE CLEAR BECAUSE THEY TEND TO OCCUR IN THE REGIME OF LOW WIND SPEEDS WHERE THE SEA SURFACE IS ALREADY ILL DEFINED 4HE CELEBRATED  SUN GLITTER MEASUREMENTS BY #OX AND -UNK  GAVE A QUANTITATIVE  MEASURE OF THE EFFECT OF CONTAMINANTS ON THE SURFACE SLOPES IN OPEN WATER  SHOWING THAT THE WIND 
 1545--1546,  Novernher. 1957.  1. 
 The evaporation duct exists over the ocean, to some degree, almost all of the time. The  height of the duct, which is usually within the range from 6 to 30 m, varies with the geographic  location. season, time of day, and the wind speed. 
 D" SPECTRUM WIDTH CAN BE EXPRESSED IN TERMS OF THE STANDARD DEVIATION BY   "FF       LN   SS   .   -4) 2!$!2  Ó°£Î "ILLINGSLEY USED THE PARAMETERS  G  VC  AND A   RESPECTIVELY  FOR THE GAUSSIAN  THE  POLYNOMIAL  AND THE EXPONENTIAL SPECTRUM MODELS )N ADDITION  THE EXPONENT  N IS NEEDED  FOR THE POLYNOMIAL MODEL 4HESE PARAMETERS WERE CHOSEN TO SIMPLIFY THE FUNCTIONAL  DESCRIPTION OF THE SPECTRUM SHAPE )N TERMS OF THE STANDARD DEVIATION OF THE SPECTRAL WIDTH IN MS  THESE PARAMETERS CAN BE DEFINED AS FOLLOWS  G V  S 
 OF 
  
 5.12. A~h =f~f FIG.16.3.—Doppler effect with c-w system. The arrangement ofFig. 
        
 BASED 3!2 $ESIGN )SSUES   4HE OPTIONS FOR SPACE 
 However, the scattering by ice spheres surrounded by a concentric film of liquid water  having a different dielectric constant does not give the same effect that Ryde’s results  for dry particles would indicate.55 For example, when one-tenth of the radius of an ice  sphere of radius 0.2 cm melts, scattering of 10-cm radiation is approximately 90% of  the value that would be scattered by an all-water drop. At wavelengths of 1 and 3 cm with 2 a = 0.126 ( a = radius of drop), Kerker, Langleben,  and Gunn55 found that particles attained total attenuation cross sections corresponding to  all melted particles when less than 10% of the ice particles was melted. When the melted TABLE 19.4  Correction Factor (Multiplicative) for Rainfall Attenuation51 Precipitation   Rate R, mm/h l, cm 0°C 10°C 18°C 30°C 40°C 0.25    0.5 0.85 0.95 1.0 1.02 0.99     1.25 0.95 1.00 1.0 0.90 0.81    3.2 1.21 1.10 1.0 0.79 0.55 10.0 2.01 1.40 1.0 0.70 0.59 2.5    0.5 0.87 0.95 1.0 1.03 1.01     1.25 0.85 0.99 1.0 0.92 0.80  3.2 0.82 1.01 1.0 0.82 0.64 10.0 2.02 1.40 1.0 0.70 0.59 12.5    0.5 0.90 0.96 1.0 1.02 1.00     1.25 0.83 0.96 1.0 0.93 0.81    3.2 0.64 0.88 1.0 0.90 0.70 10.0 2.03 1.40 1.0 0.70 0.59 50.0    0.5 0.94 0.98 1.0 1.01 1.00     1.25 0.84 0.95 1.0 0.95 0.83    3.2 0.62 0.87 1.0 0.99 0.81 10.0 2.01 1.40 1.0 0.70 0.58 150    0.5 0.96 0.98 1.0 1.01 1.00     1.25 0.86 0.96 1.0 0.97 0.87    3.2 0.66 0.88 1.0 1.03 0.89 10.0 2.00 1.40 1.0 0.70 0.58 ch19.indd   11 12/20/07   5:38:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 EXTRACTION OFINFORMATION ANDWAVEFORM DESIGN413 I'i~urt·11.7Itleal,butunattainable, amhiguity diagram. thickness attheongmpermits thefrequency andtheechodelaytimetobedetermined simultaneously toashighadegreeofaccuracy asdesired.Itwouldalsopermittheresolution joftwotargetsnomatterhowclosetogether theywereontheambiguity diagram. Naturally, it isnotsurprising thatsuchadesirable ambiguity diagram isnotpossible. 
 Thismightbeaccomplished with 100.-----------------....---------------~ ---......:--80--_ lD u L-a60U 0- C AIE40., >a ~E 20x=001 ----------=----............. -----.-:..--.:t.~ 0'0x=O"--__--1-----::::.......--.., ..............:::........---..--­.....~--­.....................--- x=0·07 -- x=01 0·1 0·01OL-------------------I.------------------l 0001 Ratioafclulterspectral widthtopulserepetition frequency (eTcI'pI Figure 4.3~Solidcurvesshowtheimprovement factorofathree-pulse canceler limitedbyplatform motion[Eq.(4.39)].DashedcurvesshowtheeffectortheDPCAcompensation. xisthefractionofthe antenna aperture thattheantenna isdisplaced perinterpulse period(x=0corresponds tonoplatform motion.) (FromAndrews.63). 
 Originally ﬁtted with ASV Mk. II radars, by August 1943 an early installation ASV Mk. IIIC was being tested by CCDU [ 10]. 
 is relatively massive and heavy because it has four servo systems for controlling . 272 INTRODUCTION TO RADAR SYSTEMS  Train  axis  (a) One-axis mount  Train /axis  (d) Two-axis mount  Type 3 Roll  al'.iS  Elevation  axis  Cross­ ~+4--1----eleva!ion  axis  (g) Three-a)(is mount  Type 3 Train  axis Train  axis  (bl Two-axis mounl  Type 1  Cross­ level  axis  -....._ Elevation  ----OXIS  (level)  Train  axis  (e) Three-axis mount  Type 1  (II) Three-axis mount  Type 4 Roll  axis (cl Two-ol'.is mount  Type 2  Cross- Ele1101ton  axis  axis  (/) Three-axis mount  Type 2  Train  oxis  __ El~va!ion  Ol(IS  -Pilch  \axis  Roll  axis  ( i) Four-axis mount  Figure 7.31 Arrangements of axes for stabilized antenna mounts. (From Cady, Karelitz, and Turner,14  chap. 
 between the vertical plane through the line of sight and the  plane perpendicular to the deck through I.he line of sight.  :\ntmna drhcs.11 <,·111 Mechanical tracking radars and nodding-beam height finders require  \':triable drive power. The choice has been between electrical and hydraulic systems. 
 Two ofthemany possible methods ofaccom- plishing this areillustrated. The components ofFig. 17.13a drawn insolid lines illustrate avery simple method. 
 In some nonradar applications, as for example radio astronomy, most of these  lossy components are not necessary as they are 'in radar, so that a low noise figure front-end  can be used effectively. However, an extremely low receiver noise-figure is not usually warranted  in radar because of the unavoidable RF losses found in most radars. Even if the noise figure of  the receiver were essentially 0 dB, the overall receiver noise-figure would still be equal to the  losses in the RF portiori of the systeni. 
 Analternative AGCfilterdesignwouldmaintain theAGCloopgainuptofrequencies muchhigherthantheconical-scan frequency. Thescanmodulation wouldbeeffectively sup­ pressedintheoutputofthereceiver. andtheoutputwouldbeusedtomeasure rangeinthe normalmanner. 
 FREQUENCY COMPONENTS OF THE NOISE 4HE AMOUNT OF NOISE REDUCTION MAY BE ESTIMATED BY COMPARING THE AREA UNDER A SPECTRAL 
 NATES  IE  SLANT RANGE AND AZIMUTH  WHILE A TWO 
       &)'52%   -ETEOR TRAIL SPECULAR SCATTERING GEOMETRY FOR SEVERAL PROPAGA 
    
 Siegd, K. M., H. A. 
 108 PROPERTIES OF RADAR TARGETS [SEC, 317 overhead trolley systems often results inaconcentration ofparticularly bright signals along such streets. The street patterns ofChicago and Detroit, partially visible inFigs. 3.36 and 3.37, areofthis type. 
 V   4HE IMAGE SIGNALS GENERATED BY GAIN AND PHASE  IMBALANCE ARE GIVEN BY %Q  AND %Q  &OR SMALL ERRORS   IF THE RATIO OF VOLTAGE  GAINS IS   o $  OR IF THE PHASE REFERENCES DIFFER BY  O  o $  RADIANS  THE RATIO OF THE  SPURIOUS IMAGE AT  
 In Proceedings of the 2017 4th International Conference on Systems and Informatics (ICSAI), Hangzhou, China, 11–13 November 2017; pp. 1272–1276. 13. 
 Gabriel123  at the Naval Research Laboratory (U.S.). Different methods for bearing estimation were  described by Gabriel and, subsequently, by other authors.34,124–130 One is the maxi - mum-entropy method (MEM) invented by J. P. 
 These differences include adaptation to environment, frequency and waveform selection, radar cross section, path losses, multipath effects, noise, interference, antenna gain, spatial resolution, and sky clutter. 5 = PavGtGrTK2«Fp ^ ^ W N0L(Iv)3R4 where S/N = output signal-to-noise ratio Pav = average transmitted power, W Gt = transmitter antenna gain G,. = receiver antenna gain T = effective processing time, s X = wavelength a = target radar cross section Fp = propagation-path factor N0 = noise power per hertz L = transmission-path and system losses R = distance between radar and target These parameters are explained as follows: 1. 
 Unlike the theoretical Dolph­ Chehyshcv pattern. the sidelobes of the Taylor pattern decrease outside a specified angular  region. The side lobe level is uniform within the region defined by I (d/'1.) sin¢ I < ii and  decreases with increasing angle¢ for i(d/'1.) sin ¢I> n, and where n is an integer, dis the  antenna dimension and A is the wavelength. 
 Theelectrical characteristics of theadhesive usedforbonding theskinstothecoremustbetakenintoaccount inthedesign sinceitcanmaketheskinlook(electrically) thickerthanitsphysical length.Thestructure mustbeprolJerly sealedagainstmoisture absorption. TheBsandwic1t isthe"inverse" oftheAsandwich. Itisathreelayerstructure whose quarter-wave-thick skinshaveadielectric constant lowerthanthatofthecorematerial. 
   '2/5.$ 0%.%42!4).' 2!$!2   Ó£°Î£  SGDT     GROUND IMPULSE RESPONSE  STT     IMPULSE RESPONSE OF TARGET  NT     NOISE D DENOTES DIRECTIONF BEING FORWARD AND R REVERSE DIRECTION  %ACH CONTRIBUTION HAS ITS OWN PARTICULAR CHARACTERISTICS THAT NEED TO BE CONSID 
 GAIN ANTENNA  !N AIR 
 TIONS MADE ON RETURNS FROM THE LAST PULSE OR FROM A SUCCESSION OF PULSES )T MAY ALSO INCLUDE MORE COMPLEX CLUTTER 
 NARY COMPONENTS  RESULTING IN AN INDEX OF REFRACTION WITH AN IMAGINARY COMPONENT  &)'52%   4HE *AUMANN ABSORBER IS A CASCADED COLLECTION OF  THIN RESISTIVE SHEETS STACKED IN FRONT OF A METAL BULKHEAD  SPACED  K  APART  WHERE  +   SPACER DIELECTRIC CONSTANT 4HE CLASSIC 3ALISBURY  SCREEN IS THE DEGENERATIVE CASE OF A SINGLE SHEET . 
 In such circumstances, the optimum radar waveform and receiver design can be  quite different than when receiver noise alone is the dominant effect.  Radar echoes from land, sea, rain, birds, and other such objects are not always undesired.  Reflections from storm clouds, for example, can be a bother to a radar that must see aircraft. 
 SCAN  COMPENSATION OF TWO RECEIVED PHASORS. Î°£È  2!$!2 (!.$"//+  4HIS SUGGESTS  THAT A CORRECTION SIGNAL IN THE REVERSE SENSE TO  $'P   BE APPLIED   AS SHOWN IN &IGURE C (ALF THE CORRECTION IS ADDED TO ONE PULSE AND HALF SUBTRACTED  FROM THE OTHER  SO THAT  #ORRECTIONSIGNAL   £  $' 4D DP    QQQ Q QQQQ Q4D DP££      WHERE 3P   WAS SUBSTITUTED FOR  'P   4HE RADAR TRANSMITS A SUM PATTERN  3P   AND  RECEIVES ON THE DIFFERENCE PATTERN  $P    SO THAT THE RECEIVED SIGNAL IS PROPORTIONAL TO  THE PRODUCT OF THE TWO )F THE SIGNAL RECEIVED ON THE DIFFERENCE PATTERN IS USED AS THE  CORRECTION  WE HAVE   %C   $P  3P      "Y COMPARING %QS  AND   WE SEE THAT FOR  %C TO APPROXIMATE THE CORRECTION  SIGNAL  THE DIFFERENCE PATTERNS SHOULD BE  $  QQQ Q £4D DP   4HE DERIVATIVE OF THE SUM PATTERN IS SIMILAR TO A DIFFERENCE PATTERN IN THAT IT IS POSITIVE  AT THE MAIN 
 Excessive energycausesthediodetoopen-circuit orthe semiconductor topuncture, resulting infailureofthedevice.Asdefinedabove,however, burnout ofadiodecanoccurbeforetheonsetofphysical destruction. Anincrease inthe receivernoiseduetotheeffectsofexcessive RFenergycanbejustasharmful ascomplete destruction; perhaps moreso,forgradualdeterioration ofperformance mightnotbenoticed asreadilyaswouldcatastrophic failure.Itisforthisreasonthatsomemeansofautomatic monitoring ofreceiver noise-figure isnecessary iftheradaristobemaintained inprime operating conditions. Adegradation inthenoisefigureofapredetermined amountusuallyisc09sidered asthe criterion fordiodefailure when defining burnout Sometimes anincrease innoisefigureof 3dBhasbeenusedasthecriterion: 9Inothercases,aI-dBincrease hasbeenused.15 However, withSchottky andpoint-contact diodes,thereisanincrease inIlfnoiseanda decrease inthebreakdown voltageatlowerpowerlevelsthanwouldbeindicated bytheabove criteria.14 Oneofthecausesofdiodeburnout inradarreceivers hasbeentheincreased RFleakage through aconventional duplexer duetoagingoftheTRtube.Whenthetransmilter fires,lhe TRtubebreaksdown.Afinitetime,usuallyontheorderofseveralnanoseconds, mustelapse beforebreakdown iscomplete. 
 Aperture blocking maybereduced bydecreasing thesizeofthesubreflector. Bymaking thefeedmoredirective orbymoving itclosertothesubreflector, thesizeofthesubreOector mayhereduced without incurring aspillover Joss.However, thefeedcannotbemadetoolarge (toodirective) sinceitpartially shadows theenergyreOected fromthemainparabolic reflector.. Main reflector with  Subreflector with  polarization -  dependent surface  Figure 7.12 Polarization-twisting Cassegraln antenna. 
 Norwood, MA: Artech House, Inc.,  1978, pp. 343–350. 75. 
 Electronic Counter-Countermeasures   .................. 9.1  9.1 Introducti on  .............................................................  9.1  9.2 Terminology  ............................................................ 
 The transmitting signal for pulse Radar is:   € Us=Assinω0t (8.3)  The reference signal:   ref ref ref t A U ϕω+ =0 sin  (8.4)  € ϕref = constant, e.g.  € ϕref=0. The receiving signal from a target at range R becomes:   € UE=AE⋅sin ω0+ωd ( )t−2ω0R c         (8.5) . 
 ING APPLICATIONS REQUIRING TRACKING MODES  POLARIZATION DIVERSITY  HIGH BEAM EFFICIENCY  OR ULTRA 
 where x rr.llr. Therms time-delay error is therefore ·  sm x waveform  X ( 11.26)  The radar waveform which yields the most accurate time-delay measurement, all other  factors being equal, is the one with the largest value of effective bandwidth /J. If the bandwidth  is limited by external factors to a value 8, the spectrum which produces the largest /J, and  hence the most accurate range measurement, would be one which crowded all its energy at the  two ends or the band; that is,  S(J) = J(J -Jo -8/2) + J(J -Jo + 8/2)  where fo is the carrier frequency and o(x) is the delta function. 
 TIES ONLY IF IT RETAINS THE RELATIVE PHASE AS WELL AS THE MAGNITUDES OF THE TWO RECEIVED AMPLITUDES  SUCH AS  % ( AND %6 IN THE LINEAR POLARIZATION BASIS )T HAS BEEN KNOWN SINCE   THAT A QUASI 
 same effect 1can beobtained bythecircuit ofFig. 16.6, which shows the basic diagram ofamicrowave pulsed radar, with theaddition ofareference oscillator. This reference oscillator provides ac-w signal with which tobeat the incoming echoes. 
 The various spurious modulations that can appear on the received signal (clutter or target return) include both carrier and pulse modulation. Carrier modulation can be amplitude modulation (AM), common FM, or inde- pendent FM. Common FM refers to identical modulation on both the transmitted signal and the receiver local-oscillator signal; independent FM appears on only one or the other or in the receiver following the first mixer. 
 I.: An Empirical Formula for the Radar Cross Section of Ships at Grazing Incidence,  IEEE Trans., vol. AES-10, p. 292, March, 1974. 
 I, 1960, pp. 48–51. 85. 
  
 __.. process11i,,  ~~ or displo1  Threshold  Following the doppler filter is a full-wave linear detector and an integrator (a low-pass  filter). The purpose of the detector is to convert the bipolar video to unipolar video. 
 For this convenience, postdetection integration is not as efficient as  predetection integration.  If PJ pulses, all of the same signal-to-noise ratio, were integrated by an ideal predetection  integrator, the resultant, or integrated, signal-to-noise (power) ratio would be exactly n times  that of a single pulse. If the same 11 pulses were integrated by an ideal postdetection device, the  resultant signal-to-noise ratio would be less than n times that of a single pulse. 
 withrangebeingthethirdcoordinate, inaddition tothetwoangles.TheAN/SPS-48 radiates multiple frequencies soastogenerate simultaneous multiple beamstopermitahigherscan ratethanwouldbepossible withasinglebeam.Sincetherangetothetargetislessasthe ~. Snoke feed I Figure8.16Planar-array frequency scanantenna consisting ofafolded-wavelength delay-line feeding asetoflinearwaveguides thataresooriented thatradiating slotsinthenarrowwalloftheguide lieintheplaneoftheantenna.63. 302 INTRODUCTION TO RADAR SYSTEMS  Figure 8.17 AN/SPS-48 frequency-scan radar antenna. 
    
 Measurements  have shown that the reflection coefficient for n~rmal (nonsmooth) ground terrain is in the  range 0.2 to 0.4 and is seldom greater than O.S. at frequencies above 1500 MHz except for tow  angles of incidence. 2•3 ·,, . 
 All klystrons, triodes, solid-state sources, etc., generate measurable noise sidebands in a band extending beyond any conceivable doppler frequency. Unless the source is unacceptably bad, these noise sidebands may be subdivided into pairs: those whose phase relationship to each other and the main carrier line is such as to represent amplitude modulation and those corresponding to a small index of frequency or phase modulation. The AM components, offset a given frequency from the carrier, are usually many decibels below the corresponding FM components. 
 7, pp. 89-90, Apr. 4th, 1974. 
 and automatic detection, 186  Range tracking, 176-177  Raster scan, 178  Rayleigh probability density function, 22-23, 47  and sea echo, 478  Rayleigh region, 33-34  Rayleigh scattering, 499  Rear-port display, 358-359  Receiver noise, 18-19  Receiver protector, 362-363  Receivers, 343-353  Recirculating-delay-line integrator, 390-392  Recursive filter, 113  Reference gain, MTI, 111  Reflectarray, 309  Reflection coefficient, or sea, 445  Reflective-array compressor, 425  Refraction, 447-450, 455-456  Refractivit;': 448  Refractometer, 455  Reggia-Spencer phase shifter, 291-293  Repeater jamming, 551-552  Resolution, of SAR, 518-519  Resonance region, in scattering, 34  Resonant-charging, modulator, 215  Resonant frequency, of tracking antennas, 179  RF keying. of Cf A, 211  Rice probability density function, 26, 50  Rieke diagram, magnetron, 195-198  Ring-bar TWT, 206  Ring echoes, 512  Ring-loop TWT, 207  Ring tuner, magnetron, 200  Rising-sun magnetron, 193, 194  Rod, radar cross section of, 34-35 Roll stabilization, 271  Rotodome, 268  Sample and hold, 156  SAR, 517-529  SAW delay lines, 424-426  SCAMP, 163  Scan with compensation, 164  Scan converter, 358 INDEX 579  Scanning-feed reflector antennas, 244-248  Schottky-barrier diodes, 347  Schwartz inequality, 372  Sea clutter, 474-489  HF radar, 533-S35  at millimeter waves, 563-564  Sea state, 475  Second-time-around echo, 3  in MTI, 117  Self-screening range, 550  Semiactive homing, 80  Sensitivity time control (see STC)  Sequential detection, 381-382  in array radar, 324  Sequential lobing, 153-154  Sequential observer, 380-382  Series-fed array, 285  Servo noise, 170  Servo system, 178-179  Shadow grid, 203  Ships, radar cross section of, 42-45  Short pulse, applications of, 421  Sideband superheterodyne receiver, 84-85  Sidelobe canceler, 333, 549  Sidelobes, antenna, 227-228  Sidelobes, FM pulse compression, 426-427  Sidelooking radar, 517  Sigma zero, 471  Signal management, in array radar, 324  Signal-to-noise ratio:  for detection, 28, 48  . for Swerling models, 47-49  Simultaneous lobing, J(j()  Sinusoidal modulation, in FM radar, 88-91  Smith chart, 196  Snake feed, 301  Snow, scattering from, 502  Snow-covered terrain, 490-491  Solar noise, 463  Sole, CF A, 209  Solid-state limiters, 363-364  Solid-state transmitters, 216-220  Space feeds, 308-309  Space-frame radome, 265-266  SPASUR, 80 . 
 Point P represents the target in the scenes. Its coordinates can be expressed as: ⎭parenleftbigg⎭radicalBig R2 0−h2cosϕ,⎭radicalBig R2 0−h2sinϕ,h⎭parenrightbigg (1) where R0is the distance between the target P and the point o. his the height of the target P . 
 Thesurfacecontour ofametal-plate lensis,ingeneral, notparabolic asinthecaseofthe reflector.7Forexample, thesurfaceclosesttothefeedisanellipsoid ofrevolution ifthesurface attheopposite faceofthelensisplane. Thespacingsbetween theplatesofthemetal-plate lensmustliebetween A/2andA.ifonly thedominant modeistobepropagated. Theindexofrefraction forthistypeofmetal-plate lensis IIII1I1111111I11 EH(3.. 
 COUPLED TECHNIQUES. £Î°xÓ  2!$!2 (!.$"//+  $IODE PHASE SHIFTERS HAVE THE ADVANTAGE OF BEING SMALL AND LIGHT IN WEIGHT EXCEPT  FOR HIGH 
 It could operate  with a peak power of 500 kW, a 1 µs pulse width, and a pulse repetition frequency of  1000 Hz that provided an average power of 500 W. Its 40% efficiency was typical for  magnetrons at that time. The compact size and efficient operation of the magnetron  at microwave frequencies allowed radars in World War II to be small enough to fly in  military aircraft and to be mobile for ground warfare. 
 Although this is not an exact relation, it is a good enough approximation for  purposes of the present discussion. If the antenna beam width were 2° and if the scanning rate  were 36°/s (6 rpm), the spread in the spectrum of the received signal due to the finite time on  target would be equal to 18 Hz, independent of the transmitted frequency.  In addition to the spread of the received signal spectrum caused by the finite time on  target, the spectrum may be further widened if the target cross section fluctuates. 
 The required  transmission powers are small because of the length of the analysis time.  FM CW Radar i n-. Radar System Engineering  Chapter 7 – CW and FM -CW Radar  47     strumentation is very often employed for th e altitude measurement of airplanes, helicopters,  and balloons. 
 Reflector- voltage tuning ranges of30to50Me/see between thehalf-power points arenormal, and thetuning rate may liebetween 1and 4Me/see pervolt. Electrical tuning isthebasis ofautomatic-frequency-control systems. Figure 11.24 shows anexterior and anx-ray view ofa2K25, awidely used local oscillator forthe3-cm band. 
 The principle behind the postdetection STC approach is illustrated in Figure 4.14,  where the return of a target in the main beam and a large discrete target in the side- lobes is plotted versus unambiguous range (that is, after the range ambiguities have  been resolved). Also shown are the normal CFAR threshold and the STC threshold  versus range. A discrete return in the sidelobes is below the STC threshold, and a  return in the main beam is above the threshold, such that the sidelobe discrete can be  recognized and blanked without blanking the target in the main beam. 
 Aircraft jet-engine modulations are likely  to be of relatively high frequency (ten to twenty kilohertz perhaps) because of the high speed of  the engine components that cause the modulated echo. The helicopter with its large rotating  blades also provides a distinctive modulation of the radar echo that distinguishes it from the  echoes of otqer aircraft. A ship is less likely to give distinctive modulations, unless it has large  rotating radar antennas or rotating machinery within view of the radar. 
 22oftheseries.. 484 THERECEIVI.VG SYSTEM-I.VDICA TORS [SEC, 13.3 ———. .—.-_—. 
 Lyzenga, and D. T. Walker, “Radar backscatter from stationary breaking  waves,” J. 
 As mentioned earlier, the unambiguous range Ru is given by  c/(2fR), where c is the speed of light and fR is the PRF. If the airborne target radial velocity to be observed is between VT,max,opening  for  opening targets (positive range rate) and −VT,max,closing  for closing targets (negative  range rate), then the minimum value of PRF,  fR min, which is unambiguous in velocity   (in both magnitude and sense, i.e., positive and negative), is  f V V VR T T g ,min ,max, ,max, ( ) = + + 2closing opening λ (4.1) where Vg is the upper limit for ground moving target rejection. V refers to the speed,  or the magnitude of the range rate.FIGURE 4.3  Clutter and clutter-free regions as a function of target velocity and azimuth NOTE:  Width of altitude-line and main-beam clutter regions varies with conditions; azimuth is measured  from radar platform velocity vector to the antenna boresight or to the line of sight to the target;  horizontal-motion case. 
 SEC. 2.11]EFFECT OFSTORAGE ONRADAR PERFORMANCE 43 tracing through anexample ofthefamiliar plan-position indicator, PPI. Suppose that theeffective storage time ofthescreen is4see, and that the angular width oftheradar beam is6°:lettherate ofrotation bevariable. 
 TURE RADAR 3!2   USED NOT ONLY FOR NAVIGATION BUT ALSO FOR ACQUISITION AND WEAPON DELIVERY TO FIXED TARGETS n 3!2 MAY ALSO BE USED TO  DETECT TARGETS IN EARTHWORKS OR  TRENCHES COVERED WITH CANVAS AND A SMALL AMOUNT OF DIRT  WHICH ARE INVISIBLE TO %/ OR )2 SENSORS 3IMILARLY  AIR 
     4HETA 
 However, it is difficult to generate and radiate high power. Limitations due to rain clutter and attenuation are increasingly difficult at the higher frequencies. Thus not many radar applications are found at these frequencies. 
 When the surface of the earth is heated sufficiently so that the air becomes hotter  than its surroundings, the buoyancy of the heated air will cause it to rise. If the source of heat is  fixed, tlie rise of buoyant air is called a thermal plume. Wllerl the rising buoyant air is  separated from the groilrid it may break away and form a freely floating thermal (convective  cell), especially if tllcre is a wind. 
 Although the airborne refractotneter may give excellent data on the variation or the index of  refrnctioti, it is riot always suitable for Inany applications since it requires an aircraft or  lielicopter  The index of refraction profile can also be determined by measuring the pressure, temper-  ature. arid humidity as a function of altitude and using Eq. (12.9) to compute the refrac-  tivity. 
 Large  antennas with narrow beamwidths can exhibit a severe degradation in gain because of  the large energy contained within the sidelobes as compared with that within the main beam.  The value of ir must be properly cl~osen consistent with the beamwidth and sidelobe  RADAR ANTENNAS 251 Therefore theapcrture distribution whichgenerates the11th(sint/!)Ncomposing patternhas uniform amplitude andisproportional tothesampled valueEs(lIA/d).Thephaseacrossthe aperture issuchthattheindividual composing patterns aredisplaced fromoneanother bya halfabeamwidth (whcrcthcbeamwidth ishcredefinedasthedistance between thetwonulls whichsurround thcmainbcam).Thcphaseisgivenbytheexponential termof~q.(7.27)and n:rresents alincarplHlsechangeofIITtradians acrossthcapcrturc. Thenumberofsamples required toapproximate theradiation pattcrnfromafiniteaperture ofwidthdis2djX Theesscntial differcncc betwecn Fouricr-integral synthesis andtheWoodward-Levinsr.;t method isthattheformergivesaradiation pattcrnwhoscmcan-squarc deviation fromtill. 
 1-9, 1976.  23. Croney, J.: Improved Radar Visibility of Small Targets in Sea Clutter, The Radio w1d Eleccro11ic  Engineer, vol. 
 no. 155.  In. 
 SCAN ACCORDING TO A 2AYLEIGH PROBABILITY DENSITY FUNCTION  A FILTERING CONSTANT OF  @     AND ASSUMING FOUR RETURNS NONCOHERENTLY  INTEGRATED IN EACH CLUTTER MAP CELL 4HE ABSCISSA IS IN RADAR SCANS  AND THE ORDINATE IS PROBABILITY OF DETECTION OF THE POINT CLUTTER SOURCE 3INCE THE CLUTTER POINT HAS THE SAME AMPLITUDE STATISTICS AS THERMAL NOISE  THE OUTPUT FALSE 
 Westinghouse Brochure: The ARSR-3 Story, no date.  47. Hartley-Smith, A.: The Design and Performance of a Modern Surveillance Radar System. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo.  GROUND ECHO  16.476x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 When c = 0, the polarization is linear with the E vector in the direction given   by y . 
 DELAY CANCELER  SETTING   $    
 A good deal of effort has gone into matching a radiator in  the presence of an array of radiators. The use of waveguide simulators as developed  by Wheeler Laboratories has made it possible to determine the matching structure  experimentally without needing to build an array. A waveguide, operating in a TE10  mode, may be considered to contain two inclined–plane waves propagating down the  guide. 
 It can be obviously seen, from Figures 8and 9, that the bottom area was under a relatively stable deformation, with higher elastic modulus and viscosity values. Under the condition of unidirectional stress, the elastic modulus equals the stress divided by the strain along the direction [ 37]. As Equation (4) shows, deformation can be understood as a temporal integration of strain. 
 J. Janza, “The analysis of a pulse radar acquisition system and a comparison of analytical mod - els for describing land and water radar return phenomena,” Ph.D. dissertation, University of New  Mexico, Albuquerque, 1963. 
 BANDWIDTH "S   PRODUCT THUS THE CLUTTER RESIDUE POWER AT EACH END OF THE PULSE INCREASES IN  PROPORTION TO THE  "S PRODUCT 4HE LIMIT ON  ) FOR A CHIRP PULSE COMPRESSION SYSTEM IS  THEN  )T "     LOG;   = TT$ &OR PULSE COMPRESSION SYSTEMS EMPLOYING PHASE 
 Kurashov, A. G. (ed.): "Shortwave Antennas," 2d ed., in Russian, Radio i svyaz, January 1985. 
 Thesignalsare frequency modulated soastoavoidtheproblems associated withtheamplitude stability of acoustic delay-iine cancelers.4!. 4.7 EXAMPLE 01; AN MTI RADAR PROCESSOR  The Moving Target Detector (MTD) is an MTI radar processor originally developed by the  MIT Lincoln Laboratory for the FAA's Airport Surveillance Radars (ASR).~~-~~ The ASR is a  nlediurn range (61) nrni) radar located at   no st rnajor United States airports. It operates at S  band (2.7- 2.9 GHz) with a pulse width of less than 1 ps, a 1.4" azimuth beamwidth, an antenna  rotati011 rate of from 12.5 to 15 rprll depending on the tnodcl, a prf from 700 to 1200 ttz  (1030 Hz typical), and an average power of from 400 to 600 W. 
 Adjusted to the  given sampling rate and range resolution cell size, the length of the CFAR- window is chosen  to be approx imately 120.  . Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  119         Figure 12.8  Sea target scenario and threshold, processed with CAGO -CFAR (L=60, α=1,  β=30). 
 FED PARABOLIC REFLECTORS 7ITH THIS METHOD  THE APERTURE FIELD DISTRIBUTION IS CALCULATED IN AN X 
 367. 29. N. 
 Sci. 2017 ,7, 772. [ CrossRef ] 227. 
 15.17. Other assumptions include that (1) the correlation lengths of  the short Bragg waves be long enough that a resonant interaction is possible, but short  enough that adjacent areas on the surface contribute to the total signal in random phase  (note how “Bragg waves” are viewed here as physical objects); and (2) the long waves  that tilt and modulate the short waves have radii of curvature sufficiently large that the  curvature over the correlation length of the “Bragg patches” is small in some sense. In  its simplest and most commonly used “tilt” form, it interprets s  0 (y ) in Eq. 
 21.7  21.4 Signal-Processing  Theory  ......................................  21.8  Detailed Resolution Analysis  ..............................  21.8 Signal-to-Noise-Ratio Considerations  ................. 
 The receiver characteristic is linear at low signal levels and logarithmic  at large signals. This is called a lin-log receiver. The logarithmic characteristic must be main­ tained to about 20 dB below therms noise level.88 A variation of the log-FTC is the log-CF AR  receiver in which the order of 10 resolution cells containing clutter are averaged by a narrow­ hand video filter with a symmetrical impulse rcsponse.90  Although the logarithmic receiver acts similarly to an automatic STC, it does not  suppress properly, as does STC, the nearby clutter echoes which enter via the sidelobes. 
 D. N. Anderson, J. 
 With its communicant ions and height-finding facilities, thetotal weight ofaninstallation oftheground radar comes to 66tons; theAN/APS-10 ismade upofafew simple units whose total weight isscarcely 120pounds. 15.12. Design Objectives and Limitations.-By theyear 1943, itwas clear that airborne radar could offer anextremely important air-naviga- tional facility. 
 The ArcSAR system scans the surrounding scenes by the antenna attached to the rotating boom which extending from the center of the rotating Sensors 2019 ,19, 2921; doi:10.3390 /s19132921 www.mdpi.com /journal/sensors 131. Sensors 2019 ,19, 2921 platform. Its synthetic aperture is generated by the rotation of the antenna [ 12]. 
 102. P. Brown and J. 
 TION FOR MAPPING GLACIER MOVEMENT OR TERRESTRIAL SUBSIDENCE )F SHORTER TIME SCALES ARE OF INTEREST  TO DETECT MOVING VEHICLES  FOR EXAMPLE '-4)   THEN A SHORTER INTER 
 The uncertainty regarding fluctuating target models makes the  use of the constant (nonfluctuating) cross section in the radar equation an attractive alterna-  tive when a priori information about the target is minimal.  2.9 TRANSMITTER POWER  The power P, in the radar equation (2.1) is called by the radar engineer the peak power. The  peak pulse power as used in the radar equation is not the instantaneous peak power of a sine  wave. 
 2.8). The first transducer is the transmission line that connects the antenna to the receiver input terminals, and the second transducer is the predetection portion of the re- ceiver itself. (As mentioned above, for purposes of signal-noise analysis subse- quent portions of the receiver are not considered.) If desired, a many-transducer receiving system could be further broken down, with a preamplifier and possibly other units considered as separate elements of the cascade. 
 The position of the first grating-lobe maxi-  mum of the synthetic array is  where d, = vlf, = spacing between elements of the synthetic array  v = velocity of vehicle carrying the radar  fp = pulse repetition frequency  The position of the first null of the real antenna is approximately 0, = A/D, where D = width of  the antenna. Since 0, must be greater than or equal to 0, to avoid grating lobes, the following  condition is obtained  The right-hand portion of the equation applies for a focused SAR, since 6,' = D/2.  Combining the restriction on prf due to i~narnbigi~oi~s range R, with that of Eq. 
 Ithas been common practice, however, tousecylindrical housings with domed ends because only tensile strains arethen involved and thehousing can bevery light. One example ofpressurized airborne container design isillustrated inFig. 11.27, and discussed fully inSec. 
   
 The  improvement in the signal-to-noise ratio might vary from 1 to 3 dB or more, over the range of  signal-to-noise ratios of interest in most radar applications. A comparison is shown in  Fig. 10.5 of the detection probabilities when the signal parameters are known completely  (coherent detector) and when the signal is known except for phase (envelope detector)." The  abscissa is plotted as 2E/No instead of signal-to-noise ratio, where E is the signal energy and  No is the noise power per hertz of bandwidth. 
   -ARCH    * " "ILLINGSLEY   ,OW 
 NIQUES TO REDUCE THE NUMBER OF DEGREES OF FREEDOM IN THE 34!0 SOLUTION ARE IMPORTANT NOT ONLY DUE TO PROCESSING REQUIREMENTS BUT ALSO BECAUSE OF THE NEED FOR SAMPLE SUP 
 ICE SIGNATURES 4O REDUCE THE POTENTIAL AMBIGUITY OF #02 AND BRIGHTNESS MEASUREMENTS  THE RADAR OBSERVATIONS MUST BE REPEATABLE AND SHOULD BE CORRELATED WITH OTHER INDICATORS #HANDRAYAAN 
 For a dedicated transmitter, the process can be reversed: fix the transmit beam  and scan the receive beam. This remedy increases the surveillance frame time by the  number of required beam steps and is usually not acceptable for large area surveil - lance. It can be considered in an over-the-shoulder geometry or when the baseline is  small. 
 A baseband algorithm implements Sensors 2019 ,19, 1649; doi:10.3390/s19071649 www.mdpi.com/journal/sensors 87. Sensors 2019 ,19, 1649 the synthetic aperture to produce the equivalent return of a very narrow azimuth antenna beam. Three main algorithms are available to obtain such high-quality images, namely Range Doppler [ 5] algorithm, Ω-K [6] algorithm and Chirp Scaling algorithm [ 7]. 
 The additional noise introduced b_y the nonoptimum gate width will result in  some degradation. The straddling loss accounts for the loss in signal-to-noise ratio for targets  not at the center of the range gate or at the center of the filter in a multiple-filter-bank  processor.  Another factor that has a profound effect on the radar range performance is the propaga­ tion medium discussed briefly in the next section and in Chap. 
 WEIGHT CANCELER  CONFIGURATIONS )F THE  
 If a signal  occupies a time T and a bandwidth B, a change in time aT allows a change in bandwidth BIu.  Thus if a signal is stretched in time, say by a factor. a = 10, the bandwidth can be reduced by a  factor of 10, and the signal can be processed with more practical narrow band circuitry. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation. 26.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 26.7 EM SYSTEM ASSESSMENT PROGRAMS Using the power of the personal computer in conjunction with the maturity of  EM system and environmental propagation modeling, assessment programs and  associated software allow a user to define and manipulate refractivity and other  natural environment data, run propagation models on that data, and display the  results in terms of expected performance on actual or proposed electromagnetic  systems. 
 14. Anand, Y., and C. Howell: A Burnout Criterion for Schottky-Barrier Mixer Diodes, Proc. 
 STATE  OR KLYSTRONS )T WOULD SEEM THAT THE #%! OUGHT TO BE OF INTEREST FOR RADAR APPLICATIONS AT FREQUENCIES AS HIGH AS  -(Z WHEN HIGHLY SHAPED PULSES NEED TO BE USED. 
 the cone-sphere can have very low backscatter energy. Suppose, for example, that the  projected area of the cone-sphere were 1 m2. The radar cross section of a sphere, with the same  projected area, at S band is about 30 dB greater. 
 Hz Sincctheoutputofthcfrequcncy counterNisaninteger,therangewillbeanintegralmultiple ofc/(4!1f)andwillgiverisctoaquantization errorequalto (3.1417)(3.14a) orc /jR=4tir 75 ('>R(m)=i1r(MHz) Notetltatthefixederrorisindependcnt oftherangeandcarrierfrequency andisafunctionof thefrcqucncy cxcursion only.Largefrequency excursions arenecessary ifthefixederroristo besmall. Sincethefixederrorisduetothediscretenatureofthefrequency counter, itseffectscan hereduced bywobbling themodulation frequency orthephaseofthetransmitter output. Wobbling thetransmitter phaseresultsinawobbling ofthephaseofthebeatsignalsothatan averagereadingofthecyclecountersomewhere betweenNandN+1willbeobtained ona normalmetermovement. 
 M. Hall and H. R. 
 Most tracking radars employ a narrow pencil-beam antenna.  Searching a volume in space for an aircraft target vith a narrow pencil beam would be  somewhat analogous to searching for a fly in a darkened auditorium with a flashlight. It must  be done with some care if the entire volume is to be covered uniformly and efficiently. 
 METER 
 Kelleher, K. S.: A New Microwave Reflector, IRE Natl. Com,. 
 (1 1.34). It states the well-known mathematical fact that a narrow waveform yields a wide  408INTRODUCTION TORADAR SYSTEMS Forabandwidth-limited" rectangular" pulseasdescribed byFig.11.5,thevalueof(X2is. cosnBr-3 nBr8(cosnBr-I)2sinnBr (nBr)3 -(nBrV-+Si(nBT) Si(nBr)+(cosnBr-1)/nBr(11.30) InthelimitasBr-+00,thevalueof(X2approaches n2r213,whichisthesameasthatobtained fortheperfectly rectangular pulse. 
 16.18 should be  attempted only after checking its validity for a particular problem. If the result of applying the technique of Eq. 16.18 to a set of measurements indi - cates that s 0 probably did vary across the significantly illuminated area, this variation  may be used as a first approximation to determine a function f(q) describing the q  variation of s 0, and a next-order approximation then becomes  σπ λ θ03 2 2 44=( ) ( ) /P P fG R dAr t t Illuminated are ea∫ (16.19) Proper scattering measurements demand an accurate and complete measurement of  antenna gain Gt. 
 The phase detector is not used since phase information is of no  interest to the tioncolierent radar. Tile local oscillator of the noncoherent radar does not have  to he as frequency-stable as in the coherent MTI. The transmitter must be sufficiently stable  over t lie pulse ditratiorl to prevent beats between overlapping ground clutter, but this is not as  severe a requirement as in the case of coherent radar. 
 4-123–4-125.  7. D. 
 D" 4AYLOR  WEIGHTING IS USED 4HE  
 TARGET IS AVAILABLE  THE 2#3 ESTIMATE CAN BE SUFFICIENTLY ACCURATE. Ó{°{È  2!$!2 (!.$"//+  EXPRESSED IN D"  ARE MEASURED 4HIS ALLOWS THE TRACKING FILTER TO ESTIMATE THE JAMMER  STATE MADE UP OF FOUR STATE COMPONENTS THE TWO ANGULAR POSITIONS BEARING AND ELEVA 
 SCAN PROCESSING CAN BE USED TO REMOVE STATIONARY POINT CLUTTER OR MOVING 
  
 630 MOVING-TARGET INDICATION [SEC. 162 Toobtain range information with thescheme ofFig. 16”4, thephones can bereplaced byanA-scope synchronized with the modulator. 
 Inthiscase,theerrorsignalcanberecovered fromtheAGCvoltagesinceit variesattheconical-scan frequency. TheAGCvoltagewillalsocontainanyamplitude fluctua­ tionsthatappearwiththeechosignal.Theerrorsignalmayberecovered fromtheAGC voltagewithanarrowbandpass filtercentered atthescan-modulation frequency. Squintangle.Theangle-error-signal voltageisshowninFig.5.6asafunction ofOr.the anglebetween theaxisofrotation andthedirection tothetarget.12ThesquintangleOfisthe. 
 I. Skolnik (ed.). McGraw-Hill Book Co., New York, 1970. 
 DOMAIN CONVOLUTION FOR A SMALL NUMBER OF COEFFICIENTS AND FREQUENCY DOMAIN CONVOLUTION FOR A LARGE NUMBER MORE THAN  OR   COEFFICIENTS. Óx°Óä  2!$!2 (!.$"//+  Óx°ÎÊ /, - /Ê  
 ITocoding and mlxmg cwcults Data transmitter ( Transmlttmg station Baw pulse ..l+13sln0 From DecoderSin pulse receiver [COS pulseRange A+B C05 f? tracking cwwt Modulator pulse Mdeo s)gnals Receiving station ::;{::1 diagramLL-UhhJ’Lw”whd.J.w.~h~ Video signals cm Video signals Espsnded ~A+Bs,nr3y A+Bcos@~ time ~le ~-~ Sm Modulator Video signals pulse pulse pulse pdse Fx~.17.12.—Ewentials forrelaying sine and cosine bypulse-timing methods. Since this general type ofsynchronization equipment has seen far more service than any other todate, itwill beworth while toconsider itinmore detail. The following section gives anextended treatment of one particular example. 
 G. W. Pulford, “OTHR multipath tracking with uncertain coordinate registration,” IEEE Trans. 
 Radar may be used to give an up-to­ date pattern of precipitation in the area around the radar. It is a simple and inexpensive gauge  for measuring the precipitation over relatively large expanses. As a rain gauge it is quite useful  to the hydrologist in determining the amount of water falling into a watershed during a given  period of time. 
 This means that the envelope of the received signal is a random variable with its  amplitude described by a Rayleigh distribution. Such distributions have been mea - sured for many ground-target echoes.23 Although the actual distributions vary widely,  no better description can be given for relatively homogeneous targets. With a Rayleigh  distribution, the 90% range of fading is about 18 dB, so an individual pulse return may  be anywhere in this range. 
 Less range eclipsing than in high PRF. Can be sidelobe clutter-free for some target aspects. Sin- gle doppler blind zone at zero velocity. 
  a N a . 4!",%    3UMMARY OF 0HASE AND !UTOCORRELATION #HARACTERISTICS OF &RANK AND ,EWIS AND  +RETSCHMER 0OLYPHASE #ODES.   05,3% #/-02%33)/. 2!$!2   n°ÓÎ &OR THE CASE WHERE  N     THE WEIGHTING FUNCTION CAN BE INTEGRATED TO OBTAIN THE FOLLOWING  RELATIONSHIP BETWEEN TIME AND FREQUENCY  T 4F "AF "   SIN   P  WHERE A    n K    K     WHICH IS SIMILAR TO THE SINE 
 (25) wecan now rewrite Eq. (24) as Average rain-echo intensity =~50Rzcr@~ Target-echo intensity .4i%, ‘(26) which displays the strong dependence ofrain echo upon wavelength and drop diameter. What has been said above pertains tothe a~erage intensity ofthe - rain echo. 
 §S SINGLE 
 A Multi-angle SAR Imaging System and Signal Model on a High-Speed Platform As shown in Figure 1, the multi-angle SAR imaging system proposed in this paper adopts the digital multi-beamforming, which uses the same antenna to form multiple beams. The squint angles of three beams are different. The date of forward-looking beam, side-looking beam and backward-looking beam are recorded simultaneously, and the data received by each channel are independent from each other. 
 For example, if the desired probability of detection were 0.95, a signal-to­ noise ratio of 6.2 dB/pulse is necessary if the target cross section were constant (case 5), but if  the target cross section fluctuated with a Rayleigh distribution and were scan-to-scan uncor­ related (case I), the signal-to-noise ratio would have to be 16.8 dB/pulse. This increase in  signal-to-noise corresponds to a reduction in range by a factor of 3.28. Therefore, if the  characteristics of the target cross section are not properly taken into account, the actual  performance of the radar might not measure up to the performance predicted as if the target  cross section were constant. 
 E V - WILL EQUALIZE THE  MULTIPLIER RESPONSE 0REDISTORTION CAN BE PERFORMED VERY PRECISELY BY ADDING THE PHASE MODULATION VIA THE $$3 THAT IS USED TO GENERATE THE CHIRP WAVEFORM 7AVEFORM 5PCONVERSION  5PCONVERSION OF EXCITER WAVEFORMS IS SIMILAR TO  DOWNCONVERSION WITHIN THE RECEIVER !LSO  SIMILAR PRACTICAL CONSIDERATIONS OF MIXER SPURIOUS AND IMAGE REJECTION APPLY 4HE ONE SIGNIFICANT ADDITIONAL CHALLENGE IS THE REJECTION OF THE ,/ LEAKAGE ,/ REJECTION TYPICALLY IMPOSES TIGHT FILTER REJECTION REQUIREMENTS ON THE 2& FILTERS  AND FOR WIDE 
 In extending the radar equation to meteorological targets.  it isassumed that rain, snow. hail. 
 OBSERVABLE ANTI 
 However, if the phase relationship is shifted 90°, as it is in the Q channel,  then all the echo pulses occur at the peaks of the doppler-frequency sine wave. Thus, to ensure  the signal will be obtained without loss, both I and Q channels are desired.  Digital signal processing has some significant advantages over analog delay lines, parti­ cularly those that use acoustic devices. 
 It is expected that legal regulations for the installation of these systems in buses and heavy transport will be first.  This is likewise expected with rail - mounted vehicles.  It is also considered possible that t he number of accidents will decrease . 
   PP n  .OVEMBER   & % .ATHANSON   2ADAR $ESIGN 0RINCIPLES  .EW 9ORK -C'RAW 
 ERATE LARGE APPARENTLY DISCONTINUOUS  REFLECTION IMAGES AND CON DUCTIVE TARGETS  WHICH  REVERBERATE BY MEANS OF STORED ENERGY  CREATE EXTENDED DEPTH IMAGES 4HE IMAGE OF A BURIED TARGET GENERATED BY A '02 WILL NOT  OF COURSE  CORRESPOND TO ITS GEOMETRICAL REPRESENTATION 4HE FUNDAMENTAL REASONS FOR THIS ARE RELATED TO THE RATIO OF THE WAVE 
 TUBE TERRITORY v  #OMPOUND  3EMICONDUCTOR -AGAZINE  *ANUARY&EBRUARY   #OLIN 7HELAN PERSONAL COMMUNICATION   2AYTHEON 2& #OMPONENTS  !UGUST  ( (OWE   3TRIPLINE #IRCUIT $ESIGN  .ORWOOD  -!   !RTECH (OUSE    PP n  $ -C1UIDDY  2 'ASSNER  0 (ULL  0  * -ASON  AND * "EDI NGER  h4RANSMITRECEIVE MODULE  TECHNOLOGY FOR 8 
 FREQUENCY INTERCHANGE DUALITY   C T   $ELTA FUNCTION IN TIME   C   F    $ELTA FUNCTION IN FREQUENCY RECTT  SINC  F    RECT FUNCTION IN TIME SINCT  RECT  F    RECT FUNCTION IN FREQUENCY EXPnPT EXPnP F 'AUSSIAN TIME FUNCTION4!",%    &OURIER 4RANSFORM 2ULES AND 0AIRS.   05,3% #/-02%33)/. 2!$!2   n°Î IS THE RANGE 
 Although modern systems typically include some  degree of channel equalization function, a reasonable degree of tracking between gain,  phase, and timing must be maintained in order to allow the channel equalization to  be performed using digital signal processing without consuming excessive processing  resources. Also, the relative stability of the radar channels as a function of time and  temperature must be such that the corrections can maintain adequate tracking during  the time between calibration intervals. Digital beamforming systems require a large number of receiver channels. 
 ROUNDING SOIL OR MATERIAL  AND THIS MEANS THAT TO A FIRST ORDER ITS RELATIVE DIELECTRIC CON 
 A phase shifter should he  able to change its phase rapidly, be capable of handling high power, require control signals of  little power, be of low Joss, light weight, small size, have long life, and be of reasonable cost. TIIE FLl'CTRONICAI.I.Y STFERED PHASED ARRAY ANTENNA IN RADAR 287  The various phase shifting techniques possess these properties in varying degree. No one  device seems to be sufficiently universal t_o meet the requirements of all applications. 
 £Î°{n  2!$!2 (!.$"//+  PARALLEL 
 W., T. P. Cheatham, Jr., and J. 
 l S)  The velocity u of an electromagnetic wave is a function of the permeability 11 and the dielectric  constant< of the medium in which it propagates. Therefore, a change in phase can be had by a  change in the frequency,· length of line, velocity of propagation, permeability, or dielectric  constant. The use of frequency to effect a change of phase is a relatively simple technique for  electronically scanning a beam. 
 C. J.. and M. 
 15.16 that make  little sense for microwave scattering from real sea surfaces, or optical limits such as  Eq. 15.17 that relate to the probability densities of specularly reflecting surface slopes.  It appears, therefore, that the use of integral formulations in the practical solution of  the sea clutter problem at microwave frequencies will require something more. 
 Coffman, “Transmit/receive module packaging: Electrical design  issues,” Johns Hopkins APL Technical Digest , vol. 20, no. 1, pp. 
 During periods ofbeacon use, the relay ofFig. 17.14 istothe right, diverting the modulator pulse from the coder tothe scale-of-two multi-. SEC. 
 SEPARATED FROM OTHER FEATURES AND A GOOD SIGNAL 
 This equation, repeated here, is (30). SEC. 3.11] EXTENDED SC’RFACE 1’ARGETS 87 Wecan generalize this formula tothecase ofanextended surface target, ifwereplace abyanexpression whose fmm will bededuced though statistical arguments similar tothose used inSec. 
 However, if the phase relationship is shifted 90", as it is in the Q channel,  then all the echo pulses occur at the peaks of the doppler-frequency sine wave. Thus, to ensure  the signal will be obtaitied without loss, both I and Q channels are desired.  Digital signal processing has some significant advantages over analog delay lines, parti-  cularly those that use acoustic devices. 
 P. Robinson: Polarization of Radar Echoes, Including Aircraft.  Precipitation. 
 This device is fairly sensitive to grating phase errors since there is only one delay path per frequency. YIG crystals15'17 provide a dispersive microwave delay. YIG devices do not have a linear delay-versus-frequency characteristic, but their delay characteristic is very repeatable. 
 ,Ê / 
 A number of radio sets do not  give satisfactory performance even when they are used  for reception direct from a broadcasting station; that  they should pick up reflections of such signals is still,  to many people, inconceivable. Yet that is just what is  happening day in, day out, with hundreds of thousands  of radar navigational and beacon stations for shipping  and for civil and military aviation, and we do take this  miracle very much for granted.  The echo comes home; but we do need a receiver  much more sensitive than the average broadcast set in  order to pick out the echo. 
 Figure 4.1226 shows the amplitude response for (1) a classical three-pulse canceler with  sin2 nf& T response, (2) a five-pulse" optimum" canceler designed to maximize the improve­ ment factor3 and (3) a 15-puJse canceler with a Chebyshev filter characteristic. (The amplitude  N  is normalized by dividing the output of each tap by the square root of L wf, where  '"' I . 112 INTRODUCTION TO RADAR SYSTEMS  2.0.---.----.-----.-----,---.----.----,---~-~-~  1.6  lJ.. 
   %,%#42/.)# #/5.4%2 
 17, pp. 140–164, 2000. ch19.indd   43 12/20/07   5:39:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Therrmode isusuallypreferred sinceitcanbemorereadilyseparated fromtheothers.Thestrapsprovide stahility sincetheyconnect allthosesegments oftheanodewhichhavethesamepotential in therrmodeandthuspermitthetubemorereadilytooperate inthispreferred mode. Insteadoftheholeandslotresonators ofFig.6.1,vanesmaybeused,asinFig.6.2a.Slots havealsobeenemployed. Whenlargeandsmallslotsarealternated, asintherising-sun magnetron structure ofFig.6.211,stableoscillation canoccurintherrmodewithout theneed forstraps,Sincetherearenostraps,therising-sun geometry ismoresuitable fortheshorter wavelengths thanareconventional resonators. 
 1  Filler  No.2 ~Jl  l>-IF .~ --.. j Filler No.3 l-~-i__  amplifier Indicator  Filter No.4  Filter No.n  (a)  ~ IF bandwidth  QJ  "' C  0 0.  Vl  (1)  0::  fi f2 f3 '4 fn  Frequency  (bl  fi~ure .16 {a) Block diagram or IF doppler filter bank; (b) frequency-response characteristic of doppler  filter hank. 
 Kolosov (ed.), Fundamentals of Over-the-Horizon Radar , in Russian, Radio i svyaz, 1984.  Also a translation by W. F. 
 17, no. 1, pp. 2-16, Spring, 1975. 
 They are therefore a powerful tool for the system designer. The predicted range is a figure of merit for a proposed radar system. It is not necessarily a complete one, since other factors such as target- position-measurement accuracy, data rate, reliability, serviceability, size, weight, and cost may also be important. 
 J.: A 110-Way Parallel Plate RF Divider/Combiner Network & Solid-State Module, Military Microwaves Conf., 1980. 20. Beltran, F.: "Multi-Port Radio Frequency Networks for an Antenna Array," U.S. 
      
 The Radiation Laboratory, once itsproposals were approved and finances provided bytheOffice ofScientific Research and Development, chose Louis N.Ridenour asEditor-in-Chief tolead and direct theentire project. Aneditorial staff was then selected ofthose best qualified for thistype oftask. Finally theauthors forthevarious volumes orchapters orsections were chosen from among those experts who were intimately familiar with the various fields, ,and who were able and willing towrite thesummaries ofthem. 
 Research, vol. 64D. pp. 
 63. Frank, R. L.: Polyphase Codes with Good Nonperiodic Correlation Properties, IEEE Trans., vol. 
 2%4 390. Oct. 25 28. 
 The modulator pulse isselected byswitch d whichis~tivated byfip-flop a. The latter istriggered atthemoment ofrecovery offlip-flop b’and endures until after the arrival time ofthe modulator pulse. Inaddition toitsfunction attheindicators this pulse also triggers theilip-flop (V~, and VW Fig. 
 Saunders, W. K.: Control of Surface Currents by the Use of Channels, IRE Trans., vol. AP-4,  pp. 
 Fig. 3.30 shows thecities ofSpringfield, Mass., and Hartford, Corm., observed atranges ofabout 10miles with a1.25-cm system. Here thebright returns form characteristic shapes roughly corresponding tothe densely built-up parts ofthe cities. 
 CIRCULAR ;,=  &URTHERMORE  SOME RADARS CAN TRANSMIT AT EITHER OF TWO ORTHOGONAL POLARIZATIONS AND RECEIVE AT EITHER OF THE TRANSMITTED POLARIZATIONS AND THE CHOICE OF TRANSMITTED AND RECEIVED POLAR 
 62, pp. 673-680. June. 
 Rotating antennas outsideofradomes cannotbe operated atwindsthataretoogreat.Theysometimes havetobeshutdownandsecurely fastened instronggalewinds.Evenifextreme windsarenotencountered, aradome-enclosed antenna has theadvantage thatitcanberotatedwithamuchsmallermotorthanifitwereoutsidethe radomeexposed toevennormalwinds. Solidreflector surfaces requiremoredrivepowerinwindthandolatticeortubular surfaces.Iftheexposed antenna issubjecttoicingthatcanclosetheholesofameshreflector, themechanical designmighthavetobemadeonthebasisofasolidsurfaceanyway. Sincethe tort~ueonanantenna depends onthewinddirection, itwillvaryastheantenna rotates.Itis oftenpossible toreducethewindtorques byselecting theoptimum position fortheaxisof rotation andbyaddingfinstothestructure. 
 UPON TEST CRITERIA COULD THEN BE DETERMINED  AND SIMULATOR SYSTEMS COULD BE BASED AT MARINE RADARnTYPE APPROVAL LABORATORIES )T HAS BEEN FOUND . 
 M. Skolnik (ed.): Radar Handbook , 2nd Ed., New York: McGraw-Hill, 1990. 56. 
 SIDELOBE REDUCTION TECHNIQUE FOR & - 
 SEC. 15.12] DESIGN OBJECTIVES AND LIMITATIONS 613 Limitations Imposed byAircraft Installation.—The performance requirements just mentioned can besimply stated, and itiseasy to check whether the completed radar meets them successfully. Neither ofthese remarks applies totheextremely important setofdesign limita- tions that arise from the fact that the radar istobeused inaircraft. 
       
 WAVENUMBER SPECTRUM ANALYSIS v  0ROC )%%%  VOL     PP n     3 - +AY  -ODERN 3PECTRAL %STIMATION 4HEORY AND !PPLICATION  .EW 9ORK 0RENTICE 
 65. Johnson, M. A., and D. 
 I. Linlor, “Electromagnetic reflection from a plane-layered  lunar model,” Journal of Geophysical Research , vol. 73, pp. 
 Worse, theresolution ofthesetwas solowthat excessive skill ininterpre- tation was needed tonavigate with thesetintheabsence ofwell-defined geographical features. Since the larger antenna required toimprove both the range and the resolution ofthis setcould not behoused in aircraft without creating excessive drag, itseemed clear that ashorter wavelength would have tobeused forgeneral navigation. The other bands atwhich components had been developed were around 3.2 cm and 1.25 cm. 
 Because the radartransmitter is resting for a time that is long with respect to the operatingtime, the average power delivered during one cycle of operation is relativelylow compared with the peak power available during the pulse time. A deﬁnite relationship exists between the average power dissipated over an extended period of time and the peak power developed during the pulsetime. The PULSE REPETITION TIME, or the overall time of one cycle of operation, is the reciprocal of the pulse repetition rate (PRR). 
   -%4%/2/,/')#!, 2!$!2   £°{£ , 
 PHASE AT SOME DESIRED POINT WITHIN THE ANTENNA 7HEN ENERGY IS INCIDENT NORMAL TO THE ARRAY  EACH ELEMENT RECEIVES THE SAME PHASE INDEPENDENT OF FREQUENCY 7HEN ENERGY IS INCIDENT FROM SOME ANGLE OTHER THAN NORMAL  THE PHASE DIFFERENCE FROM THE PLANAR PHASE FRONT TO EACH ELEMENT IS A FUNCTION OF FREQUENCY AND MOST PHASED ARRAYS WITH PHASE SHIFTERS BECOME FREQUENCY 
 DOM OR DETERMINISTIC PHASES FROM PULSE TO PULSE  WHICH ALLOWS OVERLAID ECHOES TO  BE SEPARATED -ULTIPLE 024 TECHNIQUES HAVE ALSO BEEN EXPLORED BUT ARE NOT IN COMMON USE  2ANGE AMBIGUITIES CANNOT BE TOTALLY ELIMINATED  BUT THEIR EFFECTS CAN BE SIGNIFI 
 SIN        VPVP VP      6! T JT J ! E22JT #/(/  §©¶¸ 
 SIGHT  IT MAY HAPPEN THAT MULTIPLE MEASUREMENTS EXCEED THE DETECTION THRESHOLD  BUT THE CONDITION THAT THE EXCESS IS GREATER THAN  D" WILL BE VERY UNLIKELY TO BE FULFILLED IN PRACTICE /NCE IT HAS BEEN ESTABLISHED THAT 2'0/ IS ACTIVE  SEVERAL DEVICES CAN BE ADOPTED IN ORDER TO PREVENT THE LOSS OF THE TARGET UNDER TRACK   ! FIRST APPROACH CONSISTS OF MAINTAINING TWO TRACKS UNTIL THE 2'0/ IS DEACTIVATED  ! SECOND APPROACH CONSISTS OF PENALIZING  IN THE DATA ASSOCIATION  THE MEASURE 
  4ABLE  CHARTS A SUM 
 ON 
 function of x is denoted A(x ). The (voltage) gain as a function of the angle O ( one-dimensional  radiation pattern) in the xz plane is proportional to  • D/2 ( X ) Gv(O) = I · A(x) exp j2n -1 sin O dx  • -D/2 A (11.37)  When the angle () is small, sin fJ ~ 0, and Eq. (11.37) is recognized as an inverse Fourier  transform  f 012 j2nx0 Gv(O) = _ 0 12 A(x) exp -;.-dx (11.38)  This is analogous to the inverse Fourier transform relating the frequency spectrum S(J) and  the time waveform s(t), or  <X)  s(t)= J S(f)exp(j2rrfr),{f  -<X) ( 11.39)  As the antenna scans at a uniform angular rate w.s, the received signal voltage from a fixed  point source will be proportional to Gv(B) = G11(ws l) and may be considered a time waveform. 
 Chaff may be distinguished from moving  aircraft targets on the basis of its slower velocity. Discrimination is performed eitlicr by tlic  radar operator or automatically with MTI.  Chaff dropped from an aircraft can also be used to "break lock" or1 tracking radars; that  is, if a tracking radar is "locked on" and following a particular target, the dropping of cllaff  might cause the tracker to follow the chaff and not the target. 
 Fortunately, relative height isusually sufficient foraircraft control. Further, itisgenerally possible tokeep. 192 THEGATHERING ANDPREti’ENTA TIONOFRADARDATA [SEC. 
 23, p. 21, August 1980. 28. 
 Finally, itshould benoted that the last filter can have fairly narrow pass bands, thereby considerably reducing thenoise.. SEC.5.11] PULSE-MODULATED DOPPLER SYSTEM 153 DesignProcedure.—The leading requirement inthedesign ofasystem such asthat described above was arange of75miles onsingle targets movingat speeds upto400 mph, even inthepresence ofextreme ground clutter. First, since ability todeal with multiple targets was not required, the modulation cycle was taken tobehalf onand half off. 
 Formtdation ofRequirements. Atarelatively early stage inthe development ofmicrowave techniques consideration was given tothepossibility ofapplying them totheproblem oflong-range airsurveillance. Greatly improved azimuth resolution, minimization ofground “clutter, ”and improved low-angle coverage were the principal advantages that microwaves appeared tooffer, The best. 
 V . Trunk, “Comparison of the collapsing losses in linear and square-law detectors,” Proc.  IEEE , vol. 
 Lucero incorporated a 500 W transmitter, pulse counting down and modulation circuits and the input section of a receiver. It also contained a mechanically driven aerial switch so that the two receiving aerials could be employed to achieve a split beam. It was housed in a container measuring 9 ″×8″×10″and weighed about 33 lb. 
 Aridgides, “Adaptive sidelobes cancellation of wide-band multipath   interference,” IEEE Trans ., vol. AP–33, no. 8, pp. 
 HALF OF THE ANTENNAS ALONG 
 NETIC PROPERTIES IS NECESSARY )N THE CASE OF LOSSY DIELECTRIC MATERIALS  BOTH CONDUCTION AND DIELECTRIC EFFECTS CAUSE ABSORPTION OF ELECTROMAGNETIC RADIATION 4HE ELECTROMAGNETIC MATERIAL PROPERTIES THAT DESCRIBE SUCH A SYSTEM ARE IN THE COM 
 Sidelobe radiation. An ex.ample of sidelobe radiation from a typical antenna was shown in  Fig. 7.1. 
 A single  doppler measurement and subsequent compensation might not suffice over the entire range of  the radar, especially if the radar is elevated as in an aircraft. The doppler shift from clutter will  be range dependent with an elevated radar since the doppler frequency is a function of the  elevation angle from the radar to the clutter cell. Thus more than one doppler measurement  may be necessary to compensate for the variation of the clutter doppler with range. 
 Stimson5 also discusses  these AN/APG-76 results (pp. 434, 554). Imaging of Moving Targets in SAR Images. 
 SURFACE REFLECTION COEFFICIENT FOR NOR 
 1.7 RADAR NOMENCLATURE Military electronic equipment, including radar, is identified by the Joint Electronics  Type Designation System (JETDS), as described in U.S. Military Standard MIL-STD- 196D. The letter portion of the designation consists of the letters AN, a slant bar,  and three additional letters appropriately selected to indicate where the equipment is  installed, the type of equipment, and its purpose. 
 STANCES  3ECOND  SOME REGIONS EXPERIENCE STRONG SEASONAL VARIATIONS IN VEGETATION AND SOIL MOISTURE CONTENT  WHICH MAY BE REFLECTED IN MEASURABLE CHANGES TO SCATTERING BEHAVIOR )T IS ALSO IMPORTANT TO UNDERSTAND THE EFFECT OF THE GROUND SCATTERING COEF 
 I. Abramovich, and W-M. Boerner, “Measuring polarization dynamics of the  generalized HF skywave channel transfer function,” Proc. 
 The power output will bc essentially unaltered, but amaximum change infrequent yof12Me/see occurs. Ifaheavy loading corresponding topoint Aisused, frequency shifts ofthis magnitude, and greater, arefrequently encountered and may seriously affect thesystem operation. Atpoint B,however, correspond- ingtolight loading, aphase shift of+7.5° results inonly a3Me/see fre- quency shift. 
 cc ¯¯  9UD DFD D F   TT    )N THE GENERAL CASE  WHERE THE ENERGY OF THE COMPLEX ENVELOPE IS NOT NORMALIZED  TO UNITY  THE VALUE OF THE AMBIGUITY FUNCTION AT THE ORIGIN IS EQUAL TO  %  WHERE %  IS THE ENERGY OF THE BANDPASS SIGNAL CORRESPONDING TO  UT   AND THE VOLUME UNDER THE  AMBIGUITY FUNCTION IS ALSO EQUAL TO  %  4HE NORMALIZATION CONDITION IS EQUIVALENT TO  THE ASSUMPTION THAT THE ENERGY OF THE BANDPASS TRANSMIT WAVEFORM EQUALS  * -ATCHED &ILTER 4IME 2ESPONSE  4HE MATCHED FILTER TIME RESPONSE TO A TARGET  WITH DOPPLER SHIFT  FD CAN BE EXPRESSED IN TERMS OF THE AUTOCORRELATION FUNCTION 4HE  MATCHED FILTER IMPULSE RESPONSE WITH K    AND T    IS    HT UTMF   
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 23.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 For example, in an over-the-shoulder geometry, the receiver might use a set of beams to  cover the north side of the baseline; then, as the transmit beam scans past the receiver,  it switches the set to the south side, thus halving the total number required. 
 14-23, March 1965. 10. Scavullo, J. 
 I. Skolnik (ed.),  McGraw-Hill Book Co., New York, 1970.  83. 
 W. M. Boerner et al., “On the basic principles of radar polarimetry: the target characteristic  polarization state theory of Kennaugh, Huynen’s polarization fork concept, and its extension to  the partially polarized case,” Proc. 
 Although a phase comparison is a part of the amplitude-comparison-monopulse radar,  the angular-error signal is basically derived by comparing the echo amplitudes from simulta­ neous offset beams. The phase relationship between the signals in the offset beams is not used.  The purpose of the phase-sensitive detector is to conveniently furnish the sign of the error  signal. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.556x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 In addition, many of the radar waveforms may be designed to propagate out to the  instrumented range of the radar. As a result, a major component of the dwell time at  each beam position is the time required for the pulse to propagate to the instrumented  range and back. 
 MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 The apertures are signal conditioned, controlled, and interfaced through busses in the  aircraft with remaining processing performed either in a common processor complex,  as shown in Figure 5.5, or in federated processors distributed throughout the aircraft.  One important class of standardized modules contains basic timing and programmable  event generators (PEG) that create accurate timing for Pulse Repetition Frequencies  (PRFs), analog to digital conversion (A/D) sampling, pulse and chip widths, blank - ing gates, beam repointing commands, and other synchronized real-time interrupts. A  second class contains RF and intermediate frequency (IF) amplification and mixing. 
 SENSING RADARS -ANY MEASUREMENTS OF ANGLE NOISE HAVE BEEN MADE ON A VARIETY OF AIRCRAFT  AND  THE RESULTS OF THEORETICAL STUDIES HAVE BEEN VERIFIED 4HE THEORY AND MEASUREMENTS SHOW THAT ANGLE NOISE EXPRESSED IN LINEAR UNITS OF DISPLACEMENT  SUCH AS METERS  OF THE APPARENT POSITION OF THE TARGET FROM THE CENTER OF GRAVITY OF THE TARGET IS INDEPENDENT OF RANGE EXCEPT FOR VERY SHORT RANGES  4HEREFORE  RMS ANGLE NOISE  R ANG IS EXPRESSED IN .   42!#+).' 2!$!2   °Î£ UNITS OF METERS OF ERROR MEASURED AT THE TARGET LOCATION 4HE RESULTS SHOW THAT THE RMS  VALUE OF ANGLE NOISE RANG IS EQUAL TO 2O  WHERE 2O IS THE RADIUS 
 BEAM KLYSTRONS MIGHT NOT BE WIDEBAND 4HE PRINCIPLE OF THE MULTIPLE 
 OUSLY ALL THE NECESSARY LOBES FOR ANGLE 
 n 
 26. Easton, R. L., and J. 
 3 8 The  probability density function is  m (mu)m- t ( mu) p(o-) = · 1 - exp --, (m -1). !Tav <Tav O'av (i > 0 (2.40) . 50 INTRODUCTION TO RADAR SYSTEMS  It is also called the gamma distribution. 
 K. Moore and C. S. 
 9, no. 5, pp. 867-875, l 966. 
 Statulurds (U.S.) CI~L  557, Aug. 25, 1955.  55. 
 Rept. 57-105, ASTIA Document 117067, January, 1957.  100. 
 andS;qna/P/'Occss;nq. Apr.12-14.1976.Phila.PA.lEEECat.no.76CH1067-8 ASSP.Seealsoby salllcauthors: Maximi"ing theUsableBandwidth ofMTISignalProcessors, IEEETrelliS.,vol. AES-I3. 
 During thewinter of1934-1935, theAirMinistry setup aCom- mittee fortheScientific Survey ofAir Defense. Among thesuggestions itreceived was acarefully worked out plan forthe detection ofaircraft byapulse method, submitted byaScottish physicist, now SirRobert Watson-Watt, then atthehead oftheRadio Department oftheNational Physical Laboratory. The first experimental radar system ofthetype suggested byWatson- Watt was setupinthe late spring of1935 onasmall island offtheeast coast ofEngland. 
 LENGTH FEED (OWEVER  IT IS  UNLIKELY THAT A FEED WILL PROVIDE EXACTLY EQUAL PATH LENGTHS )T WILL SUFFICE TO HAVE THE PATH LENGTHS KEPT WITHIN ONE WAVELENGTH OF EACH ANOTHER 4HE PHASE ERRORS INTRODUCED CAN THEN BE CORRECTED BY PROGRAMMING THE PHASE SHIFTERS 4HIS WILL HAVE THE BENEFICIAL EFFECT OF BREAKING UP THE QUANTIZATION ERRORS AND THEREBY REDUCING QUANTIZATION LOBES &EED %FFECT 7HEN AN EQUAL 
 146–149. 37. G.V . 
 WAVE  BISTATIC SCATTERING FROM GROUND AND VEGETATION TARGETS v  )%%% 4RANS '23 
 The information entropy in the image increases after fusion. This means the fused image contains more information about the targets.     (a) Angle 1 (b) Angle 2 Multi-angle fusion image  Figure 15. 
 RADAR RELAY [SEC,17.5 hVideosignals I y-- AnglemarksMixerVideo~ Jswitch I Ic I_——-J 1 I 1,E r— —- Signal Pulse Ceder pJ generator A generator B Fig.17.2,Flipflop f l_____J Tomcdulator Videotoindicators [;; ‘Tll=~[:;~;:.~Indicator trigger 1(‘1=~[1H Scaling Squarewave Audio I circuit J generator K filter LAmplifier l-hPulse decoder WaveformatA f=PRF WaveformatBandI WaveformatJ f=lzo Cps WaveformatK Wave form atL f’=w Cps Waveformat B CandH DandI EandM FandGSlowtimescale IIIIIIIIIIIIIIIIIIIII rI Expanded timescafu —Video— FIG. 17.4.—Simple incremental-angle synchronization.. SEC. 
 44. Green, B. A., Jr.: Radar Detection Probability with Logarithmic Detectors, IRE Trans., vol. 
 These modulations produce pulses that  resemble noise as opposed to coherent frequencies , which  makes them harder to detect . Other informati on can be  encoded into the se more complex digital modulations  as well .  Pulse Compression   Basic  pulsed  radar  using time-of-flight  to measure  target  range   has limitations. 
 The MTI  discrirniiiatiori technique results in complete loss of sensitivity for certain values of target  velocity relative to the radar. These are called blind speeds. The blind-speed problem and the  loss res~~ltirlg tllerefrom are discussed in more detail in Chap. 
 relativehumidity, andwindspeed.?!! Thesefour measurements havebeenfoundsuffiCient forthedescription ofducting conditions. Theabovehasbeenconcerned with'propagation beyondthenormalhorizon. Withinthe horizon, therefractive' effectsofthe'ductcanleadtoamodification ofthenormal lobing patterncausedbytheinterference ofthe~direct rayandthesurface-reflected ray.Therelative phasebetween thedirectandreflected rayscanbedilTerent inthepresence oftheduct.and. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 Because only one main beam is normally desired in real space, an appropriate  design will place all but one maximum in imaginary space for all angles of scan. 
 HORIZON RADAR v  -ULTIDIMENSIONAL  3YSTEMS AND 3IGNAL 0ROCESSING n 3PECIAL )SSUE ON 2ADAR 3IGNAL 0 ROCESSING 4ECHNIQUES   VOL   NO   PP n  *ANUARYn*ULY   ' ! &ABRIZIO  9 )  !BRAMOVICH  3 * !NDERSON  $ ! 'RAY  AND - $ 4URLEY  h!DAPTIVE  CANCELLATION OF NONSTATIONARY INTERFERENCE IN (& ANTENNA ARRAYS v  )%% 0ROC  VOL   PT &     NO   PP n  &EBRUARY   9 ) !BRAMOVICH  ! 9 'OROKHOV  6 . -IKHAYLYUKOV  AND ) 0 -ALYAVIN  h%XTERIOR NOISE  ADAPTIVE REJECTION FOR /4( RADAR IMPLEMENTATIONS v  )%%% )NT #ONF ON !COUSTICS  3PEECH  AND  3IGNAL 0ROCESSING   )#!330  !DELAIDE !USTRALIA     PP n  3 * !NDERSON  9 ) !BRAMOVICH  AND ' ! &ABRIZIO  h3TOCHASTIC CONSTRAINTS IN NON STATIONARY  HOT CLUTTER CANCELLATION v  )%%% )NT #ONF ON !COUSTICS  3PEECH  AND 3IGNAL 0ROCESSING    )#!330n  -UNICH  'ERMANY  VOL   PP n  !PRIL   VOL   PP  n   9 ) !BRAMOVICH  . 3PENCER  AND 3 * !NDERSON  h3TOCHASTIC CONSTRAINTS METHOD IN NON STATION 
 RADAR APPLICATIONS SUCH AS RANGE INSTRUMENTATION  WHERE THE ANGLE PRECISION REQUIRED MAY BE OF THE ORDER OF  MRAD MRAD  OR MILLIRADIAN  IS ONE THOUSANDTH OF A RADIAL  OR THE ANGLE SUBTENDED BY  
 "   3)2 
 noise, or l$ noise. Above approximately 500 kHz, the noise-temperature ratio approaches a  constant value. At a frequency of 30 MHz, a typical radar IF, it might range from 1.3 to 2.0. 
 An  approximate measure of the spectrum width can be found by taking the differential of the  doppler frequency ,fd = 2(v/l) cos 0, or  2 v Af, = - sin 0 A0 . l  where 11 = platform speed, A = wavelength, and 0 is the azimuth angle between the aircraft's  velocity and the direction of the antenna beam. (The negative sign introduced by differentia-  tion of cos O is ignored and the elevation angle is assumed to be zero.) If the beamwidth is  140INTRODUCTION TORADAR SYSTEMS filteringonasinglespectral lineofthepulsespectrum. 
 Allthe noise and the signal, ifany, from one range sweep arepiled uponone spot. IfTistheduration ofsuch asweep,’ weshould expect anincrease inS~,. due tothis superposition ofnoise, ofthe order ofV“T/r. 
 A.: The ANlTPQ-36 and ANlTPQ-37 Firefinder Radars, It~irrnarional Cot$tlr~.rrncr  RADAR-77, Oct. 25-28, 1977, IEE (London) Publication no. 155, pp. 
 On the other hand, if the PRF = 50 kHz, the time between pulses  is 20 µs, and it would not be possible to tolerate 10 µs of dead time for the switching  of phase shifters. All diode phase shifters are reciprocal along with certain types of ferrite phase  shifters. It is worth noting that, owing to losses associated with their magnetic proper - ties, ferrite phase shifters are almost never used at frequencies below 3 GHz. 
  
 19.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 frequently in clear air. The V AD technique is most often applied to wind profiler radars  that point vertically and step scan at relatively large elevation angles. An alternative  determination of boundary layer wind fields using a single weather radar has found  success using an echo tracking technique.148 Thunderstorm Prediction . 
 S.3.—Component parts oftheAN/APN-19 beacon. TheAN/A PN-19 isaIO-cm beacon designed forinstallation inaircraft. The position ofground fixed bymeasurement known points. 
 There is another technique for generating multiple simultaneous beams that does  not use beam broadening on transmit. In this technique, each pulse in the waveform is  divided into as many segments as there are beam positions. A pulse segment is transmit - ted sequentially in each of the desired beam positions, one transmit pulse right after the  other. 
 FERRITE 
 Im, E., S. L. Durden, S. 
 TION PATTERN OF THE ANTENNA MEETS THE ANTENNA PERFORMANCE SPECIFICATIONS !NTENNA CHARACTERISTICS SUCH AS SIDELOBE LEVEL AND MAIN 
 4.8 Improvements to ASV Mk. VI Over the course of time, many improvements to these radars were introduced. Somehave already been discussed, such as the attenuator being applied only to the transmitted signals and the provision of automatic increase of attenuation during arun. 
 Beste26 designed satellite constellations that provided single and triple continuous coverage by the minimum number of satellites. All these studies determined cov- erage for satellites with sensors that observe only an- gles around the nadir. Electro-optical sensors and map- ping radars are typical sensors that provide this coverage. 
 GAUSSIAN 0ARTICLE FILTERS TYPICALLY PROPAGATE A LARGE NUMBER OF RANDOM SAMPLES PARTICLES  FROM A STATE TRANSITION PRIOR DISTRIBUTION  TO ESTIMATE POSTERIOR DIS 
 However, if the correlation time is less than a batching interval, the batch processor will yield a low Pfa without modifications. Target Suppression. Target suppression is the loss in detectability caused by other targets or clutter residues in the reference cells. 
 These frequencies must be filtered at RF to prevent their reaching the mixer. H-L H . A spurious input response not predicted by the chart occurs when two or more off-frequency input signals produce by intermodulation a third frequency that lies within the RF passband. 
 Smith, “Electronic beam scanning using an array-fed dual  offset reflector antenna,” IEEE AP-S Int. Symp. Dig ., pp. 
 The two methods predict the same results in the limit KlD —» ?. However, in contrast to the aperture-field method, the current-distribution method can explain the effect of antenna surface curvature on the sidelobe levels and on the polarization. While the aperture-field method is handy for approxima- tions and estimates, another problem is that it assumes that the reflection from the surface forms a planar wavefront. 
  
 The technologies of large antenna structures in space, of large phased ar- rays in space, of large weights in space, and of large prime power systems in space are considered to be in their early stages. 2. The funds that can reasonably be spent on a space-based multimission ra- MAXlMUM DISPLAY TIME WITH TRACKING(s) VEHICLE ORBIT HEIGHT TARGET EARTH ROTATION (coe) . 
 Thetransmitter powerintroduced intotheradarequation wasassumed tobetheoutputpower(eitherpeakoraverage). However, transmitting tubesarenotalluniform inquality,norshoulditbeexpected thatanyindividual tubewillremainatthesamelevelof performance throughout itsusefullife.Alsothepowerisusuallynotuniform overtheoperat­ ingbandofthedevice.Thus,foronereasonoranother, thetransmitted powermaybeolher thanthedesignvalue.Toallowforthis,alossfactormaybeintroduced. Thisfactorcanvary withtheapplication, butlackingabetter number, alossofabout2dBmightbelIsedasan approximation. 
 A. Simpson, “Spacecraft studies of planetary surfaces using bistatic radar,” IEEE Trans.   Geoscience and Remote Sensing , vol. 
 The digital  IF-sampled output of the receiver is downconverted to baseband (DC) via a digital  product detector (DPD).22 Superior I/Q image rejection is an advantage of a DPD. The I and Q signals are passed through the digital portion of the pulse matched  filter. The combination of the IF matched filter and the digital matched filter form the  receiver’s single-pulse matched filter. 
 C antral of the radiation pattern. A particular radiation pattern may be more readily obtained  with the array than with other microwave antennas since the amplitude and phase of each  array element may be individually controlled. Thus, radiation patterns with extremely  low sidelobes or with a shaped main beam may be achieved. 
 The polar Kalman filter is rarely used because of the pseudo-accelerations intro - duced by propagating the state in polar coordinates. The Cartesian/Earth-centered  Kalman filter can work well but may have difficulty accommodating radar measure - ments of less than three dimensions. The extended/dual coordinate system Kalman  filter prevents pseudo-accelerations and accommodates measurements of any dimen - sionality. 
 17-32, 1975.  50. Murray. 
 (/2):/. 2!$!2   Óä°x£ TO VARIOUS FORMS OF CONTAMINATION AND DISTORTION  MANY IONOSPHERICALLY INDUCED   SO METHODS TO DEAL WITH THESE HAVE LONG BEEN PART OF THE RADAR SIGNAL PROCESSING  TOOLBOX   -OREOVER  THE NEED TO DEAL WITH THESE DELETERIOUS EFFECTS HAS BECOME  MORE PRESSING AS THE ACHIEVABLE DYNAMIC RANGE OF RECEIVING SYSTEMS HAS INCREASED  REVEALING A GREATER VARIETY OF SIGNAL DISTORTION MECHANISMS (ENCE  IN ADDITION TO PER 
 The a&rage clutter cross section per unit area for one set of measurements of trees and  vegetation at millimeter wavelengths is given by75.102  aO(dB) = - 20 + 10 log (0125) - 15 log R (14.37)  wlicrc 0 is tl~e grazing angle in degrees and R is in centimeters. Thus, a0 increases with  increasing frequency. Vertical polarization produced echos 3 to 4 dB greater than horizontal  polarization. 
                             . 
   %,%#42/.)# #/5.4%2 
 The attenuation may be distributed or  lumped, but it is usually found in the middle third of the tube. Although oscillation  can be prevented by distributing loss along the structure, it results in lower effi - ciency—something unattractive in high-power tubes. Instead, oscillations may be  prevented by the use of discontinuities called severs, with one sever for every 15 to  30 dB of tube gain. 
 The height or length of the parabolic cylinder must account for the finite beamwidth, shaping, and steering of the linear feed array. As Fig. 6.9 indicates, at angle 6 from broadside the primary beam intercepts the reflector at/tan 0 past the end of the vertex. 
 42 
 This provides some rejection by the  gates of undesired returns that might occur near the target, such as the echoes from  other nearby targets. Threshold devices are also used as leading- or lagging-edge  trackers by observing when the target video exceeds a given threshold level. The  point of crossing the threshold is used to trigger gating circuits to read out a target  range from timing devices or to generate a synthetic target pulse. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 21.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 shown in Figure 21.6, although it is possible to distinguish their envelopes, it becomes  increasingly difficult to resolve the actual pulses because the signal might be due to a  resonance generated by a single target; hence, in the case of pulses with an envelope  that has no minima, the 0.8 pulse width resolution criteria may not be optimal. 
 SPACE-BASED REMOTE SENSING RADARS  18.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 often is an integral number, such as the 24-day repeat of RADARSAT, although a  non-integral period may be preferred, such as the 9.916-day repeat of the TOPEX/ Poseidon radar altimeter. Orbit parameters such as repeat period must be maintained,  requiring small boosts from spacecraft thruster maneuvers,4 typically applied every  several weeks for LEO missions. The revisit time of a given SBR asset depends on the  range swath width covered by the radar in question, as well as the orbit’s exact-repeat  period and the latitude of the site of interest. 
 ' *  scan. Because of this property, the Palmer scan is sometimes used with conical-scan tracking  radars which must operate with a search as well as a track mode since the same mechanisms  used to produce conical scanning can also be used for Palmer scan~ing.~' Some conical-scan  tracking radars increase the squint angle during search in order to reduce the time required to  scan a given volume. The conical scan of the SCR-584 was operated during the search mode  and was actually a Palmer scan in a helix. 
 Hughes24) ch07.indd   14 12/17/07   2:13:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 If v~/$;'~ is increased to reduce the probability of a false alarm,  the probability of detection will be reduced also.  Equation (2.29) may be used to plot a family of curves relating the probability of detection  to the threshold voltage and to the amplitude of tlie sine-wave signal. Although the receiver  designer prefers to operate with voltages, it is more convenient for the radar system engineer to  ernploy power relationships. 
 (Copyright 1956, IEEE; after Ref. 76.)NONCOHERENT INTEGRATOR OPTIMUM BINARYINTEGRATOR BINARY INTEGRATORM = N COHERENT INTEGRATOR NONCOHERENT INTEGRATOR OPTIMUMBINARYINTEGRATORBINARYINTEGRATORM = N COHERENTINTEGRATORN - NUMBER OF PULSES N - NUMBER OF PULSES . S/N (dB) FIG. 
 The effective-earth-radius, ae, and the actual-earth-radius, a, are related  by an effective-earth-radius factor, k, such that  a k ae= (26.15) k may be computed using  ka dn dh=+1 1[ ( )] (26.16) where dn/dh is the vertical refractive index gradient. Using the mean-earth-radius of  6371 kilometers and a refractivity gradient of –39 N/km gives a k of 1.33 or about 4/3. In addition to the consideration of refraction, other standard propagation mech - anisms such as multipath interference, diffraction, troposcatter, and terrain may be  included. 
 -  I I  Primary I I feed I  I I  Figure 8.22 Principle of lens array.  308INTRODUCTION TORADAR SYSTEMS separate receivers areateachelement inareceiving array,series-feed arraysareattractive sincetheirinherent lossisatlow-power levelsandismadeupbytheamplifiers. Onemethod forproducing low-power-Ievel beamsteering istouseasingleseries-fed arrayatfrequencyI, toprovide theazimuth phasescPn.Ateachelement thesignalisheterodyned inamixerwith thesignalfromasingleseries-fed arrayatfrequency f2toprovidetheelevation phasecPm.The sumsignalatfrequency f,+f2isusedasthecarrierfrequency. 
 GINS AS THE DIRECTION OF OBSERVATION MOVES FARTHER AWAY FROM THE SPECULAR DIRECTION +ELLERS GEOMETRICAL THEORY OF DIFFRACTION  '4$  OFFERS AN IMPROVEMENT IN BOTH THE  POLARIZATION DEPENDENCE AND THE PREDICTED VALUES IN THE WIDE 
 The  parabola is illuminated by a source of energy called the feed, placed at the focus of the  parabola and directed toward the reflector surface. The parabola is well suited for microwave  antennas because (I) any ray from the focus is reflected in a direction parallel to the axis of  the parabola and (2) the distance traveled by any ray from the focus to the parabola and by  reflection to a plane perpendicular to the parabola axis is independent of its path. Therefore a  point source of energy located at the focus is converted into a plane wavefront of uniform  phase. 
 One of the advantages of an integral STC using  the diode limiter rather than a separate RF STC, is that no additional insertion loss is suffered  for the STC other than that inherent in the TR-limiter itself.  In a solid-state limiter, it is also possible to couple a noise diode into the output to  provide a convenient source for checking receiver noise-figure.40  Several hundred hours of life is considered typical for conventional TR tubes that use an  active keep-alive discharge. However, a duplexer using a passive radioactive-primed TR and  diode limiter is capable of perhaps five thousand hours of life, 50 with predictionsJof up to four  years of continuous operation.49  REFERENCES  1. 
 3 (UANG  - # +ELLEY  AND $ , (YSELL  h.ONLINEAR 2AY LEIGH 
 These are reflectors, of which China’s HJ-1-C, Germany’s SAR-Lupe,  Israel’s TecSAR, and Brazil’s MapSAR are good examples. If a reflector is driven by  multiple feeds, then one may still effect beam steering, although with rather less beam  shape variety and control than through an ESA. Space-based radar transmitters naturally fall into two classes, intimately coupled with  the antenna’s architecture. 
                  
 Radar System Engineering  Chapter 1 – History of Radar Technology  5        Figure 1.4  Radar apparatus “Würzburg Reise”, Telefunken 1941   The available script presents the principles used today and the current status of the technology.  Further relevant Literature on the history of Radar can be found in [4, 5, 11, 12].. Radar System Engineering  Chapter 2 – EM Field Theory and Wave Propagation  7     2 Electromagnetic field theory & wave propag a- tion basics  Through the analysis of the fundamental procedures of Radar technology one can no rmally a s- sume that the transmitter/receiver and the target object are in the mutual far -field. 
 L. Knapp: The Impact of Strong Scintillation on Space Based Ra- dar Design, I: Coherent Detection, IEEE Trans., vol. AES-19, July 1983. 
 POINT &&4 EXAMPLE  IF WE ASSUME THAT THE INPUT SAMPLES ARE  
 Sensors 2019 ,19, 1701   (c) Profiles of range-spread function (d) Profiles of azimuth-spread function  Figure 11. Imaging result of the forward-looking beam.  5DQJH $]LPXWK   (a) Imaging result of targets (b) Interpolation of a single point target          5DQJHVDPSOLQJFHOOG%3URILOHRIUDQJHVSUHDGIXQFWLRQ         $]LPXWKVDPSOLQJFHOOG%3URILOHRID]LPXWKVSUHDGIXQFWLRQ   (c) Profiles of range-spread function ( d) Profiles of azimuth-spread function  Figure 12. 
 K.: A Digital Mean-Clutter.:.Doppler Compensation System, N R L M emora11d11m Ri!porc  2772, Naval Research Laboratory, Washington, D.C., April, 1974.  73. Hsiao, J. 
 HATCHED REGION  WHICH SHOWS UPPER AND LOWER LIMITS ON THE AVERAGE 3#2 IMPROVEMENT FOR ALL POSSIBLE CLUTTER DOPPLER SHIFTS &OR A SMALLER NUMBER OF FILTERS IN THE DOPPLER FILTER BANK  THIS VARIATION WOULD BE GREATER &AST &OURIER 4RANSFORM &ILTER "ANK   &OR A LARGE NUMBER OF PARALLEL DOPPLER  FILTERS  HARDWARE IMPLEMENTATION CAN BE SIMPLIFIED SIGNIFICANTLY THROUGH THE USE OF THE &&4 ALGORITHM 4HE USE OF THIS ALGORITHM CONSTRAINS ALL FILTERS IN THE FILTER BANK TO &)'52%  $OPPLER FILTER BANK OF  D" #HEBYSHEV FILTERS  #0)    PULSES &)'52%   3#2 IMPROVEMENT OF  D" #HEBYSHEV DOPPLER FILTER BANK COMPARED WITH   THE OPTIMUM . Ó°xÈ  2!$!2 (!.$"//+  HAVE IDENTICAL RESPONSES  AND THE FILTERS WILL BE UNIFORMLY SPACED ALONG THE DOPPLER  AXIS 4HE NUMBER OF FILTERS IMPLEMENTED FOR A GIVEN SIZE OF THE #0) CAN  HOWEVER  BE VARIED &OR EXAMPLE  A GREATER NUMBER OF FILTERS CAN BE REALIZED BY EXTENDING THE RECEIVED DATA WITH EXTRA ZERO VALUES ALSO KNOWN AS ZERO PADDING  AFTER THE RECEIVED RETURNS HAVE BEEN APPROPRIATELY WEIGHTED IN ACCORDANCE WITH THE DESIRED FILTER RESPONSE EG  #HEBYSHEV  &ILTER "ANK $ESIGNS 5SING #ONSTRAINED /PTIMIZATION 4ECHNIQUES   &OR A  GREATER NUMBERS OF PULSES IN  THE #0)  AND WHEN  THE ECONOMY OF THE &&4 IMPLEMENTA 
 16.2 Effect of Slant Range on Doppler Effect   .............  16.4  TACCAR  ...........................................................  16.5 Platform-Motion Effect  ....................................... 
 F. M. Henderson and A. 
 I and V ol. II, Reading, MA: Addison-Wesley Publishing Company, 1981 and 1982; V ol. III,  Norwood, MA: Artech House, 1986. 
 SIVE 4HIS MONUMENT MAY CONSTITUTE ONE OF THE OLDEST STONE BUILDINGS IN %GYPT AND HENCE THE WORLD /NE OF THE MAIN GOALS OF THE PROJECT HAS BEEN TO DETERMINE WHAT  IF ANYTHING  LIES WITHIN THE ENCLOSURE $ESPITE MANY YEARS OF SURVEYING  NOTHING HAS BEEN FOUND APART FROM A SMALL AREA OF MUD BRICK PAVEMENT ! NUMBER OF RADAR SECTIONS HAD BEEN MEASURED OVER THIS AREA PREVIOUSLY  AND IN VIEW OF THE MAGNETOMETRY RESULTS  THE RADAR PROFILES WERE REEXAMINED 4HE SECTIONS HAVE BEEN MEASURED ON  METER CENTERS  SO IT WAS PURELY BY CHANCE THAT ONE RADAR SURVEY LINE WENT STRAIGHT DOWN THE FLIGHT OF STEPS EXCAVATED  SEEN IN &IGURE  WITH THE RADAR IMAGE IN &IGURE &)'52%   4EMPLE STEPS #OURTESY )%%  &)'52%   2ADAR SECTION ALONG THE FLIGHT OF STEPS #OURTESY )%%  . 
 Prati, and F. Rocca, “Nonlinear subsidence rate estimation using permanent scat - terers in differential SAR interferometry,” IEEE Trans Geoscience and Remote Sensing , vol. 38,  pp. 
 ENCE WHEN FREQUENCY SWITCHING OCCURS  4HREE SOURCES OF PHASE AMBIGUITY ARE COMMON  FREQUENCY DIVIDERS  DIRECT DIGITAL SYNTHESIZERS  AND VOLTAGE CONTROLLED OSCILLATORS 6#/  &REQUENCY DIVIDERS PRODUCE AN OUTPUT SIGNAL THAT CAN HAVE ANY ONE OF  . PHASES  WHERE  .  IS THE DIVIDE RATIO SWITCHING DIVIDERS CAN RESULT IN PHASE AMBIGUITY OF  O . )F FREQUENCY  DIVIDERS ARE USED IN THE FREQUENCY SYNTHESIS PROCESS  THEY MUST BE OPERATED CONSTANTLY WITHOUT SWITCHING THE INPUT FREQUENCY OR DIVIDE RATIO TO AVOID THIS PHASE AMBIGUITY $IRECT DIGITAL SYNTHESIZERS $$3S  CAN BE USED EITHER TO GENERATE ,/ FREQUENCIES DIRECTLY OR TO GENERATE MODULATED WAVEFORMS PRIOR TO UPCONVERSION 7HEN PULSE 
 while the bistatic radar coverage is more or less  planar. The monostatic radar is the more versatile of the two because of its ability to scan  a hemispherical volume in space and because of the relative ease with which usable target  information can be extracted from the received signal. Another advantage of monostatic radar  is that only one site is required as compared with the two sites of the bistatic radar. 
 Carbone, R. E.: A Severe Frontal Rainband, Part I: Storm-Wide Hydrodynamic Struc- ture, /. Atmos. 
 2. The most important facts concerning these detectors are the following: • The detection performances of the linear and square-law detectors are similar, differing only by less than 0.2 dB over wide ranges of PD, Pfa, and n. • Since the signal return of a scanning radar is modulated by the antenna pattern, to maximize the SIN when integrating a large number of pulses with no weight- ing (i.e., A1 = 1) only 0.84 of the pulses between the half-power points should be integrated, and the antenna beam-shape factor (ABSF) is 1.6 dB.4 The ABSF is the number by which the midbeam SIN must be reduced so that the detection curves generated for equal signal amplitudes can be used for the scan- ning radar. 
 The array operates  with a 10 MHz bandwidth centered at 442 MHz. 214 INTRODUCTION TO RADAR SYSTEMS  6.8 MODULATORS  The function of the modulator is to turn the transmitting tube on and off to generate the  desired waveform. When the transmitted waveform is a pulse, the modulator is sometimes  called a pulser. 
 TO 
 173. L. Rosenberg and D. 
 Conv. Mil. Electron. 
 Proc.IEE.vol.120,pp.1383-1390, Novemher, 1972. 60.Seesec.14.5ofref.47. 61.Andrews, G.A.:Airborne RadarMotionCompensation Techniques, Evaluation ofTACCAR, NRL Report7407,NavalResearch Laboratory, Washington. 
 1The independent variables VSWR p and phase oareused ascoordinates ofapolar diagram. Power output and frequency aremeasured forvarious points onthe diagram, and the data used toconstruct contours ofconstant frequency and constant power. Magnetron manufacturers usually furnish diagrams such asthis for every tube type, and these give information ofconsiderable importance tosystem designers. 
 TION  MAKING THEM EXTREMELY SLOW TO EXECUTE 4HE MATCHED FILTER RADAR RECEIVER PROVIDES AN OPTIMUM LINEAR PROCESSING OF RADAR IN  THE PRESENCE OF NOISE 4HE RADAR SIGNAL IS PROCESSED BY A FILTER THAT CROSS 
 In the development of models of sea scatter based on physical theory, there are  essentially two basic and distinct approaches. Historically, the first approach assumed  sea scatter to have its origin in scattering features , or obstacles, actually present on or  near the sea surface. Early scattering models included rain (to model spray),88 smooth  circular metallic disks,46,89 arrays of semi-infinite planes,90 and fields of hemispheri - cal bosses,91 to name a few. 
 L. E. Uslengh: " Electromagnetic and Acoustic Scattering by  Sirnple Shapes," North-Holland Publishing Co., Amsterdam, and Johri Wiley & Sons, inc., New York,  1969. 
 53-61, 1975.  36. Kernan. 
 14.10 Quadrature receiver. t=0 FIG. 14.11 Phasor diagram for a quadrature re- ceiver. 
 buttheyareoflimitedutilitywhenthemainbeamilluminates the topedgeofthefenceandcreatesdiffracted energy.53 Vertical polarization, oftenusedin trackers, reduces thesurface-reflected signalinthevicinityoftheBrewster angle,buthasno specialadvantage atlowangles(lessthan1.5°overwaterand3°overland).45Forasimilar reason,circular polarization hasnoinherent advantage inimproving multipath beloweleva­ tionanglescorresponding totheBrewster angle. Thebasicreasonforpoortracking atlowangleresultsfromthefactthattheconventional tracking radarwithatwo-horn feedinelevation (oritsequivalent foraconical-scan tracker) provides unambiguous information foronlyonetarget.Atlowelevation anglestwo"targets" arepresent. therealoneandits·image.Thus,theaperture mustbeprovided withmoredegrees offreedom thanareavailable fromasimpletwo-element feed.Oneapproach istoutilize multiple feedsinthevertical plane.48'5oAminimum ofthreefeeds(orelements) isnecessary toresolvetwotargets,butantennas withfromfourtonineelements intheverticaldimension havebeenconsidered. 
 Our simulation results show theeffectiveness of aspect entropy in quantifying the degree of anisotropy. As a result, we propose theextraction method of aspect entropy using real CSAR data. First, we propose the aspect entropy extraction method at the pixel level based on the sub-aperture method. 
 The assumption of a flat earth simplifies the analysis and illustrates  the type of changes introduced in radar coverage by a reflecting ground or sea surface.  Consider the earth to be a plane, flat, reflecting surface with the radar antenna located at  height ha. The target is at a height h, and at a distance R from the radar. 
 The final display was ona12-in. A-scope. The range ofatarget was determined from ascale ontheoscilloscope, and itsazimuth byrotating thegoniometer until the echo disappeared. 
 Furthermore, as will be evident later, large signal-to-noise  ratios are necessary for accurate measurements. It is also assumed that the error associated  with a measurement of a particular parameter is independent of the errors in any of the other  parameters. The validity of this assumption depends upon the availability of a large signal-to­ noisc ratio. 
 LIKE BUT SHOWS A TENDENCY TOWARD LOG 
 About 60 percent of this large number of words consists of decision tables lo locale  faults when compared to expected outputs.  The cost of the computer hardware and soft wan: of a multifunction radar system can be a  significant fraction of the total system cost. Computer system design must be integral with that  of the radar hardware itself. 
 SCAN RESULTS IN A HYPERBOLIC CROSS SECTION FROM A  TARGET  THEN AN AREA SCAN # 
 Backscatter from sea ice. At low grazing angles, as might occur with a shipboa~d radar, there  is little backscattered energy from smooth, flat ice. On a PPI or similar display the areas of  ice will be dark except perhaps at the edges. 
 ING ROUGHNESS v * 'EOPHYS 2ES  VOL   PP n     * # $ALEY  h7IND DEPENDENCE OF RADAR SEA RETURN v  * 'EOPHYS 2ES  VOL   PP n    + $ 7ARD  # * "AKER  AND 3 7ATTS  h-ARITIME SURVEILLANCE RADAR 0ART  2ADAR SCATTERING FROM  THE OCEAN SURFACE v )%% 0ROC  VOL   0T &  NO   !PRIL   3 7ATTS  + $ 7ARD  AND 24 ! 4OUGH  h4HE PHYSICS AND M ODELING OF DISCRETE SPIKES IN RADAR  SEA CLUTTER v PRESENTED AT  )%%% )NTERNATIONAL 2ADAR #ONFERENCE    ( -ASUKO  + /KAMOTO  - 3HIMADA  AND 3 .IWA  h-EASUREMENT OF MICROWAVE BACKSCATTERING  SIGNATURES OF THE OCEAN SURFACE USING 8 BAND AND +A BAND AIRBORNE SCATTEROMETERS v  * 'EOPHYS  2ES  VOL #   PP n    ! ) +ALMYKOV AND 6 6 0USTOVOYTENKO  h/N 0OLARIZATION FEATURES OF RADIO SIGNALS SCATTERED FROM  THE SEA SURFACE AT SMALL GRAZING ANGLES v * 'EOPHYS 2ES  VOL   PP n    ) +ATZ AND , - 3PETNER  h0OLARIZATION AND DEPRESSION ANGLE DEPENDENCE OF RADAR TERRAIN RETURN v  * 2ES .AT "UR 3TAND  3EC $ VOL  
 Electronic regulation ofvoltage has been used where necessary tomaintain precise voltage ortoremove the low- frequency ripple found intheoutput voltage ofmany aircraft alternators. Operational Suitability.—In contrast tothe 24controls ofthe AN/- APQ-13, the AN/APS-10 has only 10. Four must beused often, four infrequently, and the remaining two are primarily forthe convenience ofthe operator. 
 Frequency spans in the HF spectrum are allocated for various types of service such as broadcasting, point-to-point communications, maritime mobile, aeronau- tical mobile, standard frequency and time, and amateur. The variability of the sky-wave transmission medium requires different operating frequencies at differ- ent times. A single point-to-point circuit can require as many as five different fre- quencies spread over a wide range if the circuit is to be reliable over all hours of the day and seasons of the year and through the solar activity cycle. 
 Soc. Am., vol. 20,.pp. 
 The PE model is used  for ranges beyond the RO region, but only for altitudes below a maximum PE alti - tude determined by a maximum fast Fourier transform (FFT) size allowed. For ranges  beyond the RO region and above the PE region, an extended optics (XO) method is  used that is initialized by the PE model at the maximum PE altitude and uses ray optics  methods to propagate the signal to higher altitudes. Continuity of the solutions across  each region’s boundaries is kept less than 0.1 dB by careful selection of the limiting  RO grazing angle and the maximum PE propagation angle. 
 TO 
 The larger-size discretes appear with a lower density than the smaller ones, and a model commonly assumed at the higher radar frequencies is as shown in Table 17.3. Thus, as a practical matter 106 m2 discretes are rarely present, 105 m2 sometimes, and 104 m2 often. Two mechanizations for detecting and eliminating false reports from sidelobe discretes are the guard channel and postdetection sensitivity time control (STC). 
 Other factors which must be considered in selecting the optimum ~liinlber of  faces are the number of transmitters and receivers, the complexity of the control of the array,  and the total cost.  Table 8.3 summarizes the properties of N array faces to give hemispherical coverage at a  single frequency.123 In the 5- and 6-face arrays, one face is normal to the zenith, which explains  why the tilt angle is less for these two cases. Each array of a 4-face array, for example, would  scan + 55". 
 The number of samples  required to approximate the radiation pattern from a finite aperture of width dis 2d/X  The essential difference between Fourier-integral synthesis and the Woodward-Levinsr,;,  method is that the former gives a radiation pattern whose mean-square deviation from tlh.  desired pattern is a minimum. and the Woodward-Levinson method gives an antenna pattern  which exactly fits the desired pattern at a finite number of points. 
 W.: Microwave Antennas Derived from the Cassegrain Telescope, IRE Trutrs., vol. AP-9,  pp. 140-153, March, 1961. 
 FACE 4HE POSITION OF A FALSE TARGET IMAGE IN RANGE CAN BE CONTROLLED BY DELAYING IN TIME THE READ 
 The second use is for Search and Rescue Transponders   (SARTs), which are mainly designed to be deployed from life rafts after a marine acci - dent. The third category of use is for radar enhancement of small targets, such as plea - sure craft. These are called radar target enhancers  (RTE) or active radar reflectors. 
 49, pp. 143-161, May, 1958; discussion, pp. 161.- 172. 
 to the line (or plane) of the array. An endfire array has its maximum radiation parallel  to the array.  The linear array generates a fan beam when the phase relationships are such that the  radiation is perpendicular to the array. 
 vol. 21, pp. 49-53, 83, August, 1978. 
 13.29  The Composite-Surface Hypothesis  ...................  13.32  Scattering by Surface Features  ..........................  13.33  13.5 Summary and Conc lusions  ..................................... 
 However, the attractive features of the array antenna are sometimes  nullified by several serious disadvantages.  The array antenna has the following desirable characteristics not generally enjoyed by  other antenna types:  lnertialess, rapid heam-steeri11g. The beam from an array can be scanned, or switched from one  position to another, in a time limited only by the switching speed of the phase shifters. 
 The scintillation mitigation on point target. ( a) Scintillation imaging result for CkL=1033. (b) The autofocusing result. 
 Asaresult, theeffect oftherectifier resistance changes with scan angle. “Circles” ofequal range areslightly “squared, ”the “corners” coming atthe 90°positions. 1 1This effect should notbeconfused with the“square circles” found oncertain early PPI’s ofthetype shown inFig, 13.46. 
 TRUM CAN BE DEFINED BY ITS  
  Reflection of electromagnetic waves    The electromagnetic waves are reflected if they meet an electrically leading surface. If these  reflected waves are received ag ain at the place of their origin, then that means an obstacle  is in the propagation direction.     These principles can basically be implemented in a radar system, and allow the determination of the  distance, the direction and the height of the reflecting ob ject.. 
 GAUSSIAN (OWEVER  WHEN THE CLUTTER RETURNS ARE SIGNIFICANTLY NONHOMOGENEOUS  AS IS THE CASE FOR TYPICAL LAND CLUTTER RETURNS  THE PERFORMANCE OF THE CELL 
 F.: Review of Semiconductor Microwave Phase Shifters, Proc. If££, vol. 56,  pp. 
 WALL APPROXIMATIONS TO THE ZERO 
 11.6] THEMIXER CRYSTAL 413 semiconductor. Atsufficiently high frequencies, thecapacity til short- circuit thehigh back-resistance ofr.and reduce therectification efficiency. Inseries with this combination isR,theso-called “spreading resistance,” representing the bulk resistance ofthe silicon. 
  '! $ $  - &)'52%  4HE RELATIONSHIP BETWEEN THE STEADY 
 However, thereare usuallyothertargetsaswellasclutterechoespresent,sothatthreeormoredetections are neededtoreliably establish atrackwithout thegeneration offalseorspurious tracks. Although acomputer canbeprogrammed torecognize andrejectfalsetracks,toomanyfalse trackscanoverload thecomputer andresultinpoorinformation. Itisforthis·6ame reasonof avoiding computer overload thattheradarusedwithAI}Tshouldhedesigned toexclude unwanted signals,as fromclutterandinterference. 
 9. Sanders, W. K.: Post-war Developments in Continuous-wave and Frequency-modulated Radar, I RE  Trans., vol. 
 ATION OF MONITORING SCENARIOS IN THE #OLUMBIAN !MAZON v  )%%% 4RANS ON 'EOSC AND 2EMOTE  3ENSING  VOL   PP n      - # $OBSON AND & 4 5LABY  h-ICROWAVE BACKSCATTER DEPEN DENCE ON SURFACE ROUGHNESS  SOIL  MOISTURE AND SOIL TEXTURE 0ART )))SOIL TENSION v )%%% 4RANS  VOL '% 
 Middleton: Optimum Sequen_tial Detection of Signals in Noise, I RE Trans.,  vol. IT-1, pp. 5-18, December, 1955. 
 The  development of higher-powered tubes by the Eitel-McCullough Corporation allowed an  improved design of the 200-MHz radar known as XAF. This occurred in January, 1938.  Although the power delivered to the antenna was only 6 kW, a range of 50 miles-the limit of  the sweep-was obtained by February. 
 #/5.4%2-%!352%3   Ó{°x %QUATION  IS THE BASIS OF PERFORMANCE CALCULATION FOR AN 272 )T IS NOTED THAT  THE 272 DETECTION PERFORMANCE IS INVERSELY PROPORTIONAL TO  2 RATHER THAN TO  2 OF THE  RADAR TARGET DETECTION EQUATION &OR THIS REASON  THE 272 CAN DETECT A RADIATING RADAR  AT DISTANCES FAR BEYOND THOSE OF A RADARS OWN TARGET DETECTION CAPABILITY 4HE RADAR 
 10. pp. 88-95. 
 It is not ilsually applicable to aircraft  targets, but it can sometimes be applied to radars designed to detect extraterrestrial targets  such as satellites or astronomical bodies. In these cases, the transmitted pulse width is rela-  tively wide and its spectrum is narrow. The high speed of extraterrestrial targets results in  doppler shifts that are usually significantly greater than the spectral width of the transmitted  signal. 
 ING CURVATURE 
 1968–1977, 2002. 126. A. 
 However, because of this capability, the system can track multiple targets by rapidly  switching from one to another rather than continuously tracking a single tar get. The tracker simply places its beam at the location where the target is expected,  corrects for the pointing error by converting error voltages (with known angle-error  sensitivity) to units of angle, and moves to the next target. The system determines  where the target was and, from calculations of target velocity and acceleration, pre - dicts where it should be the next time the beam looks at the target. 
 TURER CLAIMS AN EXPECTED TYPICAL LIFE OF OVER   HOURS AND GUARANTEES A MINIMUM LIFE OF   HOURS )T MIGHT ALSO BE MENTIONED THAT THE MAGNETRON HAS HAD OUTSTANDING SUCCESS AS THE  POWER SOURCE FOR THE MICROWAVE OVEN /VER THE YEARS  IT HAS DEVELOPED INTO A VERY LOW COST AND HIGHLY RELIABLE GENERATOR OF MICROWAVE POWER THAT IS WELL 
  
 ~hfc/sec &psec ~lrp.sec/hr 16.6. Internal Clutter Fluctuations.-In this section weshall consider echo fluctuations due tointernal motions oftheclutter—for example, the (d (b) FIG. 16.15.—C omposit enature of ground clutter. 
 RATIO THRESHOLDS 4HE DETEC 
 Radarantennas locatedinthenoscofaircraft, however, generally requireanogive-shaped radome whichdocsnotprcscnt thcsameenvironment forallbeam posit~ons. When theantelllla isdirected forward (energypropagating paralleltotheradomeaxis) theangleof incidence ontheradomesurfacecanbeinexcessof800 •Inotherlookdirections theincidence anglemightbezcrodegrees. Sincethetransmission properties ofradomematerials varieswith angleofincidcnce andpolarization, thedcsignofanairborne radome toachieve uniform scanning properties mightnotbeeasy.Thedesignisfurthercomplicated bytheneedfor structural strength, lightning protection, andprotection fromerosionbyrain,hail,anddust.It isnotsurprising therefore thattheelectrical performance ofaradome mustsometimes be sacrificed toaccommodate theseotherfactors. 
 ING GATES  BEAM REPOINTING COMMANDS  AND OTHER SYNCHRONIZED REA L 
 R. Bean, E. J. 
  RADAR  MOUNTED ON A  
 The proposed method applies the interferometric ArcSAR to extract the DEM of scenes. The extracted DEM is utilized to assist ArcSAR imaging. This operation enables the target in the scenes image on its actual height. 
 12”5 consists ofagrounded~athode tri- ode working into agrounded-grid triode. The input impedance ofa grounded-grid amplifier stage isvery low, being approximately l/gn, or 200 ohms fora6AK5. Since this impedance loads the first stage so heavily that itsvoltage gain isabout 1,there isnotendency foritto oscillate, even without neutralization. 
 MITTER  FAILURE OF AN INDIVIDUAL OR A FEW MODULES HAS LITTLE EFFECT ON OVERALL TRANSMITTER PERFORMANCE 4HE MODULE OUTPUTS ADD AS VOLTAGE VECTORS  SO THE LOSS OF  OF THE MODULES  FOR EXAMPLE  RESULTS IN A REDUCTION TO  OF VOLTAGE OUTPUT  WHICH IS  OF POWER OUTPUT %VEN THIS IS ONLY A  
 IEEE, vol. 61. pp. 
 Also, pedestal bending from solar heating,  nonorthogonality of pedestal axes, gearing backlash, bearing wobble, granularity of  data readout, and many other factors contribute to errors. Table 9.1 lists the magnitude  of these errors for the precision instrumentation radar AN/FPS-16.22 Calibration is important to minimize errors.22 When maximum performance is  required, timely accurate calibration must be performed. The procedure may require  up to four hours to fully stabilize the radar system. 
 Illingworth, J. W. F. 
 I RE, vol.JS, pp. 53-59, January, 1950.  SJ. 
 The setting of the threshold represents a compromise between  these two types or errors. A relatively large threshold will reduce the probability or a false  alarm, but there will be more missed detections. The nature of the radar application will  influence to a large extent the relative importance of these two errors and, therefore, the setting  of the threshold. 
 Blrr. Stds., vol. 64D, pp. 
 It shows time  multiplexed operations for air-to-air (A-A), air-to-surface (A-S), electronic warfare  (EW), and communication from the same radio frequency (RF) hardware and process - ing complex often over most of the microwave band.9,11 Sometimes, multiple functions  can be performed simultaneously if a common waveform is used. The antenna aperture usually has multiple phase centers enabling measurement for  Space-Time Adaptive Processing (STAP),13 Displaced Phase Center Antenna (DPCA) FIGURE 5.1  AN/APG-79 Multifunctional AESA Radar ( Courtesy Raytheon  Company 12 ) FIGURE 5.2  MFAR interleaves A-S, A-A, and EW functions ( adapted 9 ) ch05.indd   2 12/17/07   1:26:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Therefore, upon seeing a SAR image, we may instinctively assume that  it has certain properties of a visible image, which, in fact, it does not possess. Optical  imagery is based on an “angle-angle” principle, whereas SAR imagery is based on a  very different “range-crossrange” principle. The top illustration in Figure 17.7 illustrates the appearance of a flat landscape to  the human eye (or a camera). 
 NALS WITH STRENGTHS OF  TO  M6M 4HESE AMBIENT LEVELS MUST BE ACCOMMODATED IN RECEIVER DESIGN BECAUSE A WIDEBAND FRONT END IS DESIRABLE FOR RAPID AND FREQUENT FREQUENCY CHANGES.   (& /6%2 
 TO 
 Brown, H. R. Stanley, and N. 
 for  RADARCON 98, 1998 IEEE Radar Conference , 12–14 May 1998, pp. 9–14. ch10.indd   30 12/17/07   2:19:39 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Remote Sens. 2008 ,46, 3019–3030. [ CrossRef ] 5. 
  
 Univ. (Nat. Sci. 
 C., et al.: RF Systems in Space—Space Antennas Frequency (SARF) Sim- ulation, General Research Corporation, RADC IK-38-91, Final Tech. Rept., vol. I, April 1983. 
 Let the one-way-power antenna pattern be approximated by the gaussian expression  exp (-2.78lJ2/0i), where 8 is the angle measured from the center of the beam and 08 is the  beamwidth measured between hair-power points. If n8 is the number of pulses received within  the half-power beam width 08, and 11 the total number of pulses integrated (11 does not neces­ sarily equal 118), then the beam-shape Joss (number greater than unity) relative to a radar that  integrates all n pulses with an antenna gain corresponding to the maximum gain at the beam  center is  11 Beam-shape loss= (n-i,,2 ··--·-·--·-- (2.51)  1 + 2 L exp ( -5.55k2 /ni)  ,. = 1  For example, if we integrate 11 pulses, all lying uniformly between the 3-dB beamwidth. 
 ICE  SCATTERING  AT   '(Z IN SUMMER AND WINTER  AFTER ! , 'RAY ET AL   Ú )%%%  . £È°{n  2!$!2 (!.$"//+  AND   ET %VVJT K ZV   2E 
 NING  SHORT WAVELENGTH RADARS MOUNTED ON TOWERS OF OPPORTUNITY  PRIMARILY CELL PHONE TOWERS THAT BLANKET MUCH OF THE 53   %XISTING EQUIPMENT ON THESE TOWERS WILL  &)'52%    6ECTOR WIND FIELDS IN A HORIZONTAL  PLANE DERIVED FROM DUAL 
 Because ofthe technique used inproducing it,this display iscalled adelayed PPI. As intheopen-center PPI, range and bearing retain their identities and their linearity. The deformation isvery great except atthe extreme edge of thedisplay. 
 The null will also show up if the mutual-coupling coefficients are measured and used to calculate the reflection coefficient. Array Simulators. A good deal of effort has gone into matching a radiator in the presence of an array of radiators. 
 0538, Fig. 37, wehave fullconstruc- tive interference. The deflection oftheA-scoue. 
 SEGMEN T TRACES AS SHOWING PRI 
 The local oscillator ofthereceiver isalso frequency-stabilized against acavity. The circuits and layout ofthei-famplifier and theautomatic gain control aresimilar tothose ofthe receiver described inSec. 12.11, thebandwidth being 11Me/see. 
 the performance usually deteriorates even more than can be accounted  for hy the above losses, especially when the equipment is operated and maintained by inexper­ ienced or unmotivated personnel. It may even apply, to some extent, to equipment operated hy  professional engineers under adverse field conditions. Factors which contribute to field degra­ dation arc poor tuning, weak tubes, water in the transmission lines, incorrect mixer-crystal  current, deterioration of receiver noise figure, poor TR tube recovery, loose cable connections,  etc. 
 8.14, requires a finite time to . 300 INTRODUCTION TO RADAR SYSTEMS  70°  60°  Q)  g' 50 ° ·· L irnit for  0 d O 6 X.0 § 40°  u  lfl 30° .  20° . 
 Godlove, T. F., V. L. 
 TOR  R 3TEADY 
 ALTITUDE hPOP 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar.  METEOROLOGICAL RADAR  19.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 performance since the large clutter targets are limited in radar cross section by Mie  scattering, whereas the atmosphere-borne wind tracing scatterers are small and obey  Rayleigh scattering cross section physics. 
 47, pp. 59-65, January/February, 1977.  76. 
 76. G. V . 
 310 ANTENNAS, SCANNERS, AA’D STABILIZATION [SEC. 917 sphere with theantenna imagined atitscenter. Alllettered points are onthesphere: Zisthezenith, Mistheprolongation ofthemast, and H istheship’s heading. 
 As a result of Class-C-biased amplifier operation, when a rectangular RF drive pulse is applied to a module, the amplifier will typically show rise and fall times that are on the order of nanoseconds. The output signal spectrum of this pulse shape may not meet spectral emissions requirements, and it may be necessary to slow the rise and fall times. This becomes very difficult when stages are serially cascaded. 
 (Re- printed with permission from E. D. Ostroff et al., "Solid-State Transmitters," Artech House, Norwood, Mass., 1985.) Phased Array Transceiver Module Design. 
 17. Ctii~. T. 
 Hansen  (ed.), Academic Press, New York, N.Y., 1966, chap. I.  19. 
 When the gates are not centered about the target video, so that the early gate  extends past the center of the target video, the early-gate capacitor charged posi - tively receives a greater charge. The late gate sees only a small portion of the pulse,  resulting in a smaller negative charge. Summing the capacitor voltages results in a  negative output. 
 TUBE TRANSMITTER WITH PROPERLY SHAPED 2& DRIVE  FOR EXAMPLE  THE SPECTRUM WIDTH AT  D" DOWN CAN USUALLY BE NARROWED BY ABOUT AN ORDER OF MAGNI 
 The height oftargets could beestimated with thehelp ofnulls inthevertical antenna pattern (Sec. 611). Despite itsearly design and itslack ofadequate coverage against low-. 
 Frequency considerations. The ARSR-3 described above operates al L band (1250 to  1350 MHz). This is a good compromise frequency for a long-range air-surveillance radar. 
 Equation (21.71) has been derived by Jack Walker.8 Related developments in- volving use of the projection-slice theorem have been given by a number of other authors.9'19 In interpreting Eq. (21.71), it is useful to consider the point r as a general point on the object being imaged and r' as a reference point on the object. The vector q is then the vector from the reference point to all other points on the object, and the integration extends over the object. 
  PERFORMED THE FIRST SIMPLE RADAR MEASUREMENTS OF  6ENUS FROM A SPACECRAFT  6ENERA 
 13.7.  Log-FTC and log-log receivers. The techniques discussed thus far attempt to improve the  detection of targets in clutter by increasing the target-to-clutter ratio. 
 (2.26)  In 24 3 84≈. (2.27)  In 36 160≈. (2.28) ch02.indd   23 12/20/07   1:44:15 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
  Ê " "*1 - 
 103. Joli~ison, M. A. 
 CHANNEL MONOPULSE RADAR SYSTEM   FROM 2 3 .OBLIT  . °£È  2!$!2 (!.$"//+  BEAMS IS SQUINTED IN OPPOSITE DIRECTIONS FROM THE ANTENNA AXIS AND ROTATED LIKE A PAIR  OF CONICAL 
 One of the main advantages of MIMO technique is that the number of virtual antennas grows as the square of the number of physical antennas; it is therefore possible to generate a large number of virtual elements, exploiting a relatively small number of physical antennas, with a signiﬁcant cost and complexity reduction of the imaging system hardware. 2.1. MIMO Array Factor Consider a MIMO array working with central wavelength λ, the corresponding array factor FMIMO (e)is given by the product of the transmitting and the receiving array factors: FMIMO (e)=FTX(e)FRX(e)=1 Nei4π λr∑ m,lei4π λ(xm+yl 2)·e(2) 120. 
 39,  pp. XO 87, June 27. 1966. 
 For this pu rpose a sim u- lated sea target scenario in the video domai n, consisting of 15 targets, sea clutter and two rain  areas are considered. In this example the length of the sea targets (ships) is between 20 and  200 m. After the A/D- conversion, the video signal is sampled at a rate of 50 ns, corresponding  to a range resolution cell of 7.5 m. 
 Wetzel, “On the theory of electromagnetic scattering from a raindrop splash,” Radio Sci .,  vol. 25, No. 6, pp. 
 It is desirable to center the clutter spectrum in the notch (i.e., minimum- response region) of the AMTI filter in order to obtain maximum clutter rejection. This can be accomplished by offsetting the IF or RF frequency of the radar signal by an amount equal to the average doppler frequency of the clutter spectrum. Since the clutter center frequency varies with range and azimuth when the radar is moving, it is necessary for the filter notch to track the doppler-offset fre- quency, using an open- or closed-loop control system such as TACCAR, de- scribed below. 
 Several factors tend to spread the CW signal energy over a finite frequency band. These  must be known if an approximation to the bandwidth required for the narrowband doppler  filter is to be obtained.  If the received waveform were a sine wave of infinite duration, its frequency spectrum  would be a delta furiction (Fig. 
 Multi-sensor inverse synthetic aperture radar imaging and phase adjustment based on combination of sparsity and total variation. J. Appl. 
 Rec., pt. 5, pp. 88-94, New York, 1959. 
 10.166 and c. Taylor Weighting with Linear FM. The spectrum of a linear-FM pulse with a rectangular time envelope is not exactly rectangular in amplitude, nor is its phase exactly matched by the linear group delay of the compression filter.2'39'42 The discrepancy is particularly severe for small time-bandwidth products. 
 SIDEBAND PHASE 
 The reflector  gain, Gr, is described by  Gr ≈ Gf  × M 2 × cos(qr) (12.29) where Gf is the gain of the feed array and qr is the scan angle of the reflector (second - ary) beam. The second property defines the scanning. The reflector scan angle, qr, is  defined by the following equation:  qr ≈ qf /M (12.30) where qf is the feed scan angle. 
 Ritipwalt. 1). L.. 
 J. Doviak, V . Bringi, A. 
 ,Ê *- )N MANY -4) RADAR APPLICATIONS  THE CLUTTER 
 (All functions illustrated are symmetrical about t = 0.) The sidelobe adjacent to the main lobe has a magnitude of —13.2 dB with respect to the main-lobe peak. The sidelobe falloff rate is very slow. Pair 3. 
 19, 1984. 152. R. 
 Without a canceler, heavier weighting is needed to reduce sidelobes to a level  so that the filter response to main-beam clutter is below the thermal-noise level. This  weighting increases the filter noise bandwidth and hence increases the loss in signal- to-noise ratio. Choosing the proper weighting is a compromise between rejecting main-beam  clutter and maximizing target signal-to-noise ratio. 
 The decision threshold T for the ith cell is  T = A Si−1 (7.17) where the clutter is estimated using a simple feedback integrator  Si = K Si−1 + Xi (7.18) FIGURE 7.20  Rank detector: output of a comparator C is either a zero or a  one ( from G. V . Trunk7) ch07.indd   18 12/17/07   2:13:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 surface to the radar beam are the two sources. Over a smooth ocean surface, they  are separated only in the elevation coordinate so that most of the error appears  in the elevation-tracking channel. 
 Middleton25 states that when the probability of  false alarm is 0.05, the probability of detection is 0.90. A false-alarm probability of 0.05 is  usually high for most radar applications. Radar false-alarm probabilities are rarely greater  than 10-4• Low values of false-alarm probability with the Ideal Observer require extremely  large values of detection probabilities. 
 POLARIZED SCATTER  OFTEN  BY ABOUT  D" #ROSS 
 4.  pp. I8 23. 
 KM SWATH  DUAL 
 Aferrite is a magnetizable metal-oxide insulator which contains  magnetic ions arranged to produce spontaneous magnetization while maintaining good dielec-  tric proper tie^.^' -29 In contrast to ferromagnetic metals, ferrites are insulators and have a high  resistivity which allows electronlagtietic waves to penetrate the material so that the magnetic  field component of the wave can interact with the magnetic moment of the ferrite. This  iriteractior~ results in a change of the microwave permeability of the ferrite. The term ferrirttag-  r~erisru was introduced to describe the novel magnetic properties of these materials that are  now known as ferrites. 
 FIRST 
 4P B  AS SEEN BY THE APERTURE ILLUMINATION FUNCTION   DUE  TO THE APPARENT MOTION  VX Q  OF THE SCATTERER RELATIVE TO THE ANTENNA AT POSITION  X AND C  STEP 
 DIMENSIONAL MAP COL 
 However, if the entire angular region is swept within  a single pulse by a frequency-scan antenna, the response from a point target will be frequency­ modulated due to the finite beamwidth. A dispersive time delay filter can cause the received  echo to be compressed so as to achieve better range resolution. The amount of range­ resolution possible is limited by the finite time-delay of the signal propagating through the  frequency~scan feed network. 
 %  2USSIA      3 -ULTIMODE (* 
 Bomer and M. Antweiler, “Polyphase Barker sequences,” Electronics Letters , vol. 23, no. 
 STATE RADAR TRANSMITTER ARE THAT  IT CAN OPERATE WITH WIDE BANDWIDTHS IT HAS THE POTENTIAL FOR LONG LIFE AND IT IS FAVORED BY SOME BUYERS OF RADAR )T CANNOT  HOWEVER  EMPLOY HIGH PEAK 
 ING SURVEILLANCE OF AIRCRAFT  HELICOPTERS  MISSILES  AND UNMANNED AIRBORNE VEHICLES   CONTROL OF WEAPONS TO AN AIR INTERCEPT  HOSTILE WEAPONS LOCATION MORTARS  ARTILLERY  AND ROCKETS   DETECTION OF INTRUDING PERSONNEL  AND CONTROL OF AIR TRAFFIC 4HE USE OF RADAR FOR BALLISTIC MISSILE DEFENSE HAS BEEN OF INTEREST EVER SINCE THE  THREAT OF BALLISTIC MISSILES AROSE IN THE LATE S 4HE LONGER RANGES  HIGH SUPERSONIC SPEEDS  AND THE SMALLER TARGET SIZE OF BALLISTIC MISSILES MAKE THE PROBLEM CHALLENGING 4HERE IS NO NATURAL CLUTTER PROBLEM IN SPACE AS THERE IS FOR DEFENSE AGAINST AIRCRAFT  BUT BALLISTIC MISSILES CAN APPEAR IN THE PRESENCE OF A LARGE NUMBER OF EXTRANEOUS CON 
 A  FILTER  DESCRIBED BY   XSK    XP K    @ ;XMK   
 4.18.22 The dashed curve is the response of a five-pulse canceler  with fixed prf and with weightings of i 1, -3i, 1, l The solid curve is for a staggered prf with  0  -10  en -20 ::9.  ()j  Ill  C  0 a.  Ill 30 '" 0:  -40 I  I I  I  I  l I I I ii ti  11 II  II I  I  \ :  I I  \ I  I I I I ·  II II  ---- Fixed prf  --- Staggered prf \ I  I I  I I  I I \ /  \ I I l  I ,' I  I I II " II ,,  Target velocity relative to first blind velocity ol fixed prf \  I  \  I  I  I  \ I I  I  I  I  I  Figure 4.18 Response of a weighted five-pulse canceler. 
 Since the phases of these waves are lost, the spectrum gives no information about the morphology of the surface itself, i.e., about the complex surface features that are responsible for the scattered field. This point will be raised again in the section below on theories of sea clutter. General Sea Descriptors. 
 LINE APPROXIMATION TO TWO 
 37.Swerling, P.:Probability ofDetection forFluctuating Targets,IRETrans.,vol.1T-6,pr.269-30H, April,1960. 38.Nathanson, F.E.:..RadarDesignPrinciples," McGraw-Hili BookCompany, NewYork,1969, chap.5. 39.Wilson, J.D.:Probability ofDetecting Aircraft Targets, IEEETrans.,vol.AES-8,pp.757-761, November, 1972. 
 1097–1105. 25. He, K.; Zhang, X.; Ren, S.; Jian, S. 
 TO 
 To measure the individual frequencies, they must be separated from one another. This  might he accomplished with a bank of narrowband filters, or alternatively, a single frcqucncy  corresponding to a single target may be singled out and continuously observed with a narrow-  banci tiinable filter. Hiit if the motion of the targets were to procJ11cc ii doppler frccl~lency sl~ilt,  or if the frequency-modulation waveform were nonlinear, or if the mixer were not operated In  its linear region, the problem of resolving targets and measi~ring the range of each becomes  more complicated. 
 Electro-optical devices such as TV, IR, or lasers can be used in conjunction with radar to  provide tracking at low target altitude when the radar errors are unacceptable. These devices,  however, are of limited range and are not all-weather.  5.6 TRACKING IN RANGE3•55-58  In most tracking-radar applications the target is continuously tracked in range as well as in  angle. 
 J.. J. Frank, and T. 
 In principle, the size and shape of a target can be found by measuring the  backscattered field, or radar cross section, at all frequencies and all aspects. It is not possible,  of course, to obtain such complete information, but the process can be approximated by  measuring the backscatter at a finite number of frequencies and aspects. The name inverse  scatteri11g5 u'has hecn used to describe this method for obtaining the target size and shape, and  thus provide a means for target classification. 
 GROUND STARLIGHT AND ENERGY FROM THE -OONS INTERIOR  SO THAT THE AMBIENT TEMPERATURE WOULD BE NO MORE THAN  ^ + !S WATER 
 picture. The efficiency issomewhat less than that oftheP-1 screen. 3.Applications inwhich the scanning issoslow that considerable persistence isneeded toafford viewing time and toprovide acom- posite picture. 
 Ward, R. J. Phillips, R. 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 25.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 now aligned in time as they pass through the remaining processing do not actually cor - respond to the same points on the IF signal input’s time line, since the I and Q samples  were derived from alternate ADC samples. However, the Q filter with alternate coef - ficients negated, shown in Figure 25.18, actually approximates the half-sample delay FIGURE 25.17   Direct digital downconverter: ( a) baseline implementation, ( b) decimating before filters,  and ( c) inverting every other sample after decimation75 MHz IF  SAMPLED  @ 100 MHzτ 2τ 2τ 2τ 2τ 2τ 2τ 2τ ADDI Q2 2c0 c2 c4 c6  c8 c1050 MHz 100 MHz +1, –1, +1, –1,...(a)c5 75 MHz IF  SAMPLED  @ 100 MHzτ τ τ τ τ τ τ τ ADDI Q2 2 c050 MHz 100 MHz +1, –1, +1, –1,...(b)c5 c10 c8 c6 c4 c2 75 MHz IF  SAMPLED  @ 100 MHzτ τ τ τ τ τ τ τ ADDI Q2 250 MHz100 MHz +1, –1, +1, –1,... 
 It consists of a rod or a bar of ferrimagnetic material located at the center  of a section of waveguide. A solenoid is wound around the waveguide to provide a longitudinal  magnetic field. A change in phase is obtained by a change of the applied magnetic field that  results from a change of the current passing through the coil. 
 Their phase centers are separated by the distance d. If the aircraft is moving at ground speed V8, then the phase centers move VgTp during the interpulse period Tp. In Fig. 
 Phase and amplitude stability 4. Cooling requirements A direct compromise must be made between the noise temperature and the dynamic range of a receiver. The introduction of an RF amplifier in front of the mixer necessarily involves raising the system noise level at the mixer to make the noise contribution of the mixer itself insignificant. 
 [ CrossRef ] 9. Ran, L.; Liu, Z.; Zhang, L.; Li, T.; Xie, R. An Autofocus Algorithm for Estimating Residual Trajectory Deviations in Synthetic Aperture Radar. 
 The response of the single-delay-line canceler will be zero whenever the argu­ ment rrJj Tin the amplitude factor of Eq. (4.6) is 0, n, 2n, ... , etc., or when  (4.7)  where 11 = 0, 1, 2, ... 
 DIMENSIONAL SOLUTION TO THE THREE 
 SECTION IN &IGURE   HAS POWER PERFORMANCE LIMITATIONS THAT ARE MITIGATED BY EMPLOYING A STRUCTURED DESIGN APPROACH FOR ACHIEVING HIGH POWER 
 r pfifirfFW r *max [(410'(5/AOn^WJ u>6; The quantities (S/N)min and J5 as here defined are to be evaluated at the antenna terminals, and that fact detracts from the utility of this form of the equation. As thus defined, (S/N)min is not independent of Bn, and the depen- dence is difficult to take into account in this formulation. If that dependence were ignored, this equation would imply that /?max is an inverse function of Bn, i.e., if all the other range-equation factors were held constant, RmSLX could be made as large as desired simply by making Bn sufficiently small. 
 Byclosing the relay onto point Y and inserting aproper electronic switch between Xand Y,themodulator trigger signal can beused asaswitching signal when cyclical time sharing with beacon orother signals isdesired. Ifnosuch need isinvolved, the cosine pulse can serve also asthemodulator trigger signal sothat delay circuit acan beomitted and points Band Cmade the same. The coded pulses and the video signals aremade toshare the radar cycle byaswitch operated byaflip-flop keyed bythemodulator trigger, asdescribed inprevious cases. 
 An airborne SAR moving target imaging and motion parameters estimation algorithm with azimuth-dechirping and the second-order keystone transform applied. IEEE J. Sel. 
 ALARM RATE ,IMITER  IS A VERY EFFICIENT CONSTANT 
 202 207. April. 1958. 
 ERAL TECHNIQUES AVAILABLE TO IMPLEMENT ONE 4HE MOST STRAIGHTFORWARD APPROACH IS TO SIMPLY PERFORM A COMPLEX MULTIPLY  AS SHOWN IN &IGURE  )N THIS EXAMPLE  THE COMPLEX INPUT SAMPLE IS DENOTED AS !    J"  WHICH IS MULTIPLIED BY  THE COMPLEX COEF 
 $ v PRESENTED AT RD !-3 !NNUAL -EETING RD !) #ONF    0  ,ONG "EACH    $ !TLAS  h2ADAR CALIBRATION SOME SIMPLE APPROACHES v  "ULL !M -ETEOROL 3OC   VOL     PP n    * & 0RATT AND $ ' &ERRARO  h!UTOMATED SOLAR GAIN CALIBRATION  PREPRINTS v IN  TH #ONF 2ADAR  -ETEOROL  !-3  4ALLAHASSEE    PP n  $ 3IRMANS AND " 5RELL  h/N MEASURING 732 
 DENSITY PLASTIC FOAM COLUMN  THE STRING SUSPEN 
 Ahigh-velocity flow ofperhaps 50ft/sec isnecessary to achieve afigure of0.04 watts/in2 per“C. IAmer. Sot. 
 Noncoherent comparison  FIGURE 17.13  Layover:  (a) Perspective view, ( b) view along platform flight path, and ( c) view  in coordinate system of SAR image ( Courtesy of SciTech Publishing, Inc .) ch17.indd   29 12/17/07   6:49:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 
 W .. Jr.: Digital MTI Radar System, U.S. Patent No. 
 419 11.11 Design Considerations forthe R-f Head 421 11.12 Illustrative Examples ofR-f Heads 425 CWP, 12. THE RECEIVING SYSTEM—RADAR RECEIVERS 433 INTRODUCTION ............................433 12.1 The Role ofthe Receiving System. 433 12.2 ATypical Receiving System 435 THE RECEIVER ......... 
 357–381, March 1973. 43. R. 
 TINED FOR THE -OON  -ARS  OR ANY OTHER PLANETARY BODY IS TO MAX IMIZE ITS MEASUREMENT  POTENTIAL  WHILE ALSO MINIMIZING ITS RESOURCE DEMANDS PRINCIPALLY POWER AND MASS  )F  SENSITIVITY TO FROZEN VOLATILES IS A REQUIREMENT LEVIED ON A PLANETARY EXPLORATORY RADAR   THEN THE SYSTEM SHOULD BE DUAL 
 366-373, Nov. 1967.  54. 
 Provisions may also be in­ corporated in the radar for locating equipment failures so that faulty circuits can be easily  found and replaced.  Instead of displaying the" raw-video" output of a surveillance radar directly on the CRT,  it might first be processed by an automatic1detection and tracking (ADT) device that quantizes  the radar coverage into range-azimuth resolution cells, adds (or integrates) all the echo pulses  received within each cell, establishes a threshold (on the basis of these integrated pulses) that  permits only the stroug outputs due to target echoes to pass while rejecting noise, establishes  and maintains the tracks (trajectories) of each target, and displays the processed information . THE NATURE OF RADAR 7  to the operator. 
 Goldstein, H.: The Effect of.Clutter Fluctuations on MTI, M1T.Radiurion Lab. Rept. 70, Dec. 
 main linetransform toanimpedance lower than normal and then back tonormal. The conditions fornoreflec- tion aresatisfied. Atafrequency lower, forexample, than thecenter fre- quency, thestub isless than aquarter wave, but theinductive reactance thereby presented attheT-junction ismade just enough tocompensate forthefact that the quarter-wave transformers inthe main line arealso less than aquarter wave long, and would present amismatch inthe absence ofthe stub. 
 The basic oceanographic  descriptor of the sea surface, however, is the wave spectrum , which says little about  the details of these features, but contains a great deal of information about the sea  surface in general and is central to the application of the Bragg scattering hypothesis.  Accordingly, some tutorial material describing the spectral characterization of the sea  surface is included in this section, along with a brief discussion of surface events such  as wave breaking and other surface effects thought to contribute to the production of  sea spikes . There are basically two types of surface waves, capillary  and gravity , depending  on whether surface tension or gravity is the dominant restoring force. 
 Unlikeconventional microwave radar,thespecific frequency tobeusedbyanOTHradarisafunction oftherange thatisdesiredandthecharacter oftheionosphere. Sincetheionosphere varieswithtimeof day,season,andsolaractivity, theoptimum radarfrequency willvarywidely.Suchradars musttherefore becapableofoperating overawideportionoftheHFband,asmuchasthree octaves (4to32MHzforexample).21 Theionosphere oftenconsists ofmorethanonerdract­ ingregion.Thehighestregion,denotedF2,andthemostimportant forHFprop'agation, isat altitudes offrom230to400km.Itprovides thegreatest-ranges forasinglerefraction andcan support thehighestusablefrequencies. TheF1region,fromabout180to240km,isobserved onlyduringthedayandismorepronounced duringthesummer thanthewinter.TheEregion, whichliesbetween 100and140km,canalsosupport refraction. 
 RANGE 
 L. Drake, and C. M. 
 J. Harris, Multirate Signal Processing for Communication Systems,  Upper Saddle River, NJ:  Prentice Hall, 2004. 11. 
 A technique that can operate on the basis of a single  pulse. and therefore is more applicable to the phased array, has been c~lled the~  approach; or more descriptively, the _ _as.y.mme-u:iC-m.at:tQ/lY.1~!·48 Two asymmetrical patterns are  generated and squinted above the horizon to minimize response to the surface-reflected signal.  The two patterns are constrained so that their rati°' has an even-order symmetry about the  horizon. 
 VERTICAL SCATTERING IS MUCH GREATER AT HIGHER FREQUENCIES &OR THE  
 If“off-centering” is desired, itisprovided bymeans ofafixed coil outside ofthemoving one. 2.The “resolved time base” method, inwhich asawtooth waveform ispassed through a2-phase resolver, 1practically always asynchro, and the resulting sweep “components” are utilized toenergize orthogonal deflecting coils orplates. 3.The method of“pre-time-base resolution” inwhich slowly varying sine and cosine voltages obtained from ad-cexcited sinusoidal potentiometer orbyrectification ofsignals from ana-cresolver are used togenerate the necessary sawtooth. 
 The cancellation of the stationary-target echo is limited to the level of the spurious echo. It is clear that the overall filtering capability of the radar, its ability to enhance the desired echoes and suppress undesired interference, may be degraded by the spurious responses of the various mixing stages. Particularly susceptible to deg- radation are MTI and pulse doppler radars, which may not provide the expected improvement in the rejection of clutter if the coho is not at the same phase con- dition each time that the transmitter pulses. 
 1950.  77. Woodward, P. 
 Workers in the field of optics have from time to time devised lenses in which  the index of refraction varied in some prescribed manner within the lens. Although such lenses  had interesting properties, they were only of academic interest since optical materials with the  required variation of index of refraction were not practical. However, at microwave frequen­ cies it is possible to control the index of refraction of materials (r, is the square root of the  dielectric constant <), and lenses with a nonuniform index of refraction are practical. 
 MENTAL ELEMENTS AND TO CONFORM TO THE PLATFORMS SHAPE 2ADOMES WILL HAVE A LOSS THAT MAY DEPEND ON THE SCAN ANGLE OF THE ANTENNA 4HIS LOSS MUST BE ACCOUNTED FOR ON TRANSMIT AND RECEIVE IE  A TWO 
 T. Lo and S. W. 
 A directive antenna not only provides the  transmitting gain and receiving aperture needed for detecting weak signals, but its narrow  beamwidth allows the target's direction to be determined. A typical radar might have a heam-  width of perhaps one or two degrees. The angular resolution is determined by the beamwidtli,  but the angular accuracy can be considerably better than the beamwidth. 
 FOLD SPREAD IN THE VALUE OF THIS PARAMETER  FROM THE %ARTH TO *UPITERS MOON %UROPA )T FOLLOWS THAT RADAR DESIGNS THAT WORK IN ONE SITUATION MAY NOT BE AT ALL APPROPRIATE IF MIGRATED TO A DIFFER 
 PHASED ARRAY RADAR ANTENNAS  13.416x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 With a change in frequency, a nondispersive transmission line having free-space  propagation characteristics and a length L equal to the size of the aperture that it feeds  will produce a linear-phase variation across the aperture with a maximum value at the  edges of  ∆∆ψπ λmax=f fL2rad  where ∆f / f is the fractional change in frequency. This linear-phase progression across  the aperture will scan the beam by  ∆∆qq0 01=f fcosrad  For one direction of scanning, this effect will add to the aperture effect; for the  opposite direction, it will tend to cancel the aperture effect. In a waveguide, with the  guide wavelength denoted l g, the effect is more pronounced and the resultant change  in beam position is  ∆∆qq0 01=λ λgf fcosrad  When analyzing an end-fed series feed, it is necessary to consider both the feed  effect and the aperture effect. 
 .. '.\;;<:'/,t,<';? ,. Figure6.10Photograph oftheV!\-87E6-cavity S-bandklystron mounted onadolly.(Courtesy Varian Associates, fllc,.PaloAlto,CA.) beamvoltageof65kVisrequired anditspeakbeamcurrentis34amperes. 
 22thevertical angles have been exaggerated, forclarity.) Substitution ofthis expression forainthe radar equation, and the replacement, ofRbyh/sin 0,hbeing theheight oftheaircraft, leads to s=P= =p~2&;&4 ‘.(4r)’R4(6b) IfSistobeindependent of0between O=00and 8=7r/2, wemust require that G(o) vary aaCSC2 0through this angular interval. The ideal antenna pattern then would bedescribed by G=Go=& for00<0< ~/2, G=O,atallother angles. }(7) The requirement ofEq. 
 Noise  ultimately limits the capability of any radar. The problem of extracting information from the  received waveform is described in the next chapter. The detection of signals in the presence of  clutter is discussed in Chap. 
 3CATTER 2#3 2EGION  4HE THIRD BISTATIC 2#3 REGION  FORWARD SCATTER   OCCURS WHEN THE BISTATIC ANGLE APPROACHES  n 7HEN  A   n 3IEGEL SHOWED   BASED ON PHYSICAL OPTICS  THAT THE FORWARD 
 h–ρcurve. It can be seen in Figure 12that as hincreases,ρgradually decreases. When h=100 m,ρdecreases to 0.89. 
 Jackson: Wide-angle Scanning Performance of Mirror Antennas, M arco11i  Rev., vol. 19, 3d qtr., pp. 119-140, 1956. 
 For ground echo, the distance is doubled, so the  pattern of an echoing patch of length L has lobes of width l/2L. This compares with l/L  for an antenna of the same cross-range length. Because the excitation of the elements of  the scattering array is random, the scattering pattern in space is also random. 
 Multi-temporal InSAR is a well-established technique currently applied to displacement monitoring thanks to the availability of reliable processing tools developed during the last two decades, as well as data archives continuously updated by operative satellite missions. Nowadays, there is an increasing need for advanced, application-oriented procedures for analysing the InSAR-based displacement records. In [13], high-resolution RADARSAT-2 SAR data were processed through the Small BAseline Subset (SBAS) algorithm for deriving 3-year displacement time series over Wuhan city, which su ﬀers from subsidence problems related to urban construction. 
 GRAND OF %Q   IT SHOULD BE POSSIBLE  AT LEAST IN PRINCIPLE  TO REPLACE  #Y  DIRECTLY  BY THE &OURIER TRANSFORM OF  7+  THE INVERSE OF %Q  FOR  N       THUS PROVIDING  A DIRECT FUNCTIONAL RELATIONSHIP BETWEEN THE RADAR CROSS SECTION AND THE SEA WAVE SPEC 
 Record, vol. I, pt. 2, pp. 
 [CrossRef ] 6. Wang, C.H.; Liao, G.S.; Zhang, Q.J. First spaceborne SAR-GMTI experimental results for the Chinese Gaofen-3 dual-channel SAR sensor. 
 DEPENDENT VELOCITY INCREMENT CONTAINING  BUT NOT ENTIRELY EXPLAINED BY  WIND 
 L.: Passive ECM Applied to False Target Elimination, Record of tire I £EE 1975 lnt1.1ma­ tio11al Radar Co11/ere11ce, pp. 458-462. IEEE Publication 75 CHO 938-1 AES. 
 radars in a rain squall and with a choppy sea. Three ships bearing 225˚, 294˚ and 330˚ shown on the 10 cm. radar right are not shown on the 3 cm. 
 TRARY PHASE SHIFT BY IMPLEMENTING MULTIPLE STAGES OF PHASE SHIFTS  WHERE THE TANGENT OF THE PHASE SHIFT IN EACH SUCCESSIVE STAGE IS THE NEXT SMALLER FRACTIONAL POWER OF   AND MULTIPLICATION BY THIS NUMBER CAN BE IMPLEMENTED BY SHIFTING THE INPUT DATA BITS AN INTEGER NUMBER OF PLACES 4HE FIRST FEW STAGES ARE AS FOLLOWS  )    COSP ;) n 1TANP  =   COSP ;) n 1 =   1   COSP ;1   )TANP  =   COSP ;1   ) =   )   COSP ;) n 1TANP  =   COSP ;)  
 Within-pulse sca~ining.~~.~' In the frequency-scan 3D radar discussed above, a single pencil  bean1 is step-scanned in elevation. Each pulse is at a constant frequency but the frequency is  cliatiged every pulse or every few pulses to position the beam at different elevation angles.  Aliotlier r~letllod of utilizing a frequency-scan antenna is to sweep the frequency over the entire  I'recluuicy s;~~lgc or1 c~ccc.11 1111lsc so that energy is radiated tliroughout the entise elevatioti  coverage I'or tile duration of a single pulse. 
 C. McCormick: Deterioration of Circular-polarization Clutter Cancellation in  Anisotropic Precipitation Media, Electronics Letters, vol. 10, no. 
 Tl”ith sweeps aain(a),equal intervals between replies willbeobtained forallfrequencies. For(~)thedistribution depends onthefrequency. Sweeping Frequency. 
 Sensors 2018 ,18, 3750 Figure 8. Imaging results of traditional approach and proposed approach under 20% of effective data. (a) Traditional imaging processing; ( b) imaging processing of proposed approach (mixed Euclidean norm); interferometric phase images (top layer); complex images of channels 1 and 2 (second and third layers); ﬁnal 3-D imaging results (last layer). 
 Arabian Sea (Area 4). The dominating meteorological factor in the Arabian Sea region is the southwest monsoon, which blows from early June to mid-September and covers the whole Arabian Sea with moist-equatorial air up toconsiderable heights. When this meteorological situation is developed fully, nooccurrence of ducting is to be expected. 
 W. Shrader, “MTI radar,” Chap. 17 in Radar Handbook , M. 
 MARILY RECEIVER NOISE IN THE LOWEST BRANCH  DISTRIBUTED SPATIALLY HOMOGENEOUS  CLUTTER IN THE MIDDLE BRANCH  AND GENUINE SEA SPIKES IN THE BRANCH CONTAINING THE HIGHEST CROSS SECTIONS  SOME OF WHICH EXCEED  M  &OR THE HIGHER WIND SPEEDS AND FULLY  DEVELOPED SEAS ENCOUNTERED IN THE  .ORTH !TLANTIC  THE PERCENTAG E OF SEA SPIKES IN THIS  POPULATION WAS FOUND TO GROW AS THE TH POWER OF THE WIND SPEED  WHICH  INTEREST 
 Figure 25.7 shows the theoretical bistatic RCS of two perfectly conducting spheres as a function of bistatic angle.1'92"95 For the larger sphere (near the optics region) the pseudo-monostatic region extends to p = ~ 100°, with an error of 3 dB. And even for the smaller sphere (in the resonance region) the pseudo-monostatic region extends to P = ~ 40°. Measurements38 of a sphere with a = 0.42 X, where a is the sphere radius, match within 3 dB the values for the smaller sphere in Fig. 
 = O K < g/U2 (13'4) where the cutoff wavenumber corresponds to the frequency fm of the peak in Eq. (13.3). Opposed to this highly simplified form are increasingly complex spectra based on more careful empirical studies18 as well as more sophisticated theoret- ical considerations.19'20 In discussing the characterization of the sea surface by its spectrum, it must be kept in mind that the spectrum is a highly averaged description of how the energy of the surface is distributed among the wavenumbers, or frequencies, of the waves present on it. 
 MATION PROCESS &)'52%   /VERALL SENSITIVITY OF AN AUTOMATIC DETECTION AND AUTOMATIC  TRACKING PROCESS WORKING TOGETHER 4HE SINGLE 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 3.2 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 where ts is the scan time and Ω is the surveillance volume coverage requirement (prod - uct of the azimuth and elevation angles). 
 BINING THE SUBARRAYS FOR SUITABLE SUM AND DIFFERENCE PATTERNS &IGURE  A SHOWS  A METHOD OF COMBINING OPPOSITE SUBARRAYS INTO THEIR SUMS AND DIFFERENCES !LL SUM CHANNELS ARE THEN ADDED WITH PROPER WEIGHTING TO OBTAIN THE DESIRED AMPLI 
 4, pp. 539–550, April 1999. 12. 
   2!$!2 #2/33 3%#4)/.   £{°{x  % & +NOTT ET AL  2EF   PP n  + - -ITZNER  h)NCREMENTAL LENGTH DIFFRACTION COEFFICIENTS v .ORTHROP #ORPORATION  !IRCRAFT $IV  4ECH 2EPT !&!, 
 A more efficient estimation technique is described by Rummler.40 This esti- mator makes use of the fact that the complex autocorrelation function of the sig- nal has the general form • 4-TTVR(X) = P^(x)e>^-x (23.32)A. where P(JC) is the correlation coefficient and Jt is a dummy variable. It follows that V9 the mean velocity, is given by v = ^arg [R(X)] (23.33) It can also be shown that , X2 [ R(x) ]av2 « -^- 1 -— (23.34) V to?A R(o)-N\ where N is the noise power. 
 S  NEW EXPERIMENTAL RESULTS WERE OBTAINED   WHICH SHOWED THAT  THE SPECTRUM FALL 
 This isdiscussed further inSec. 8.9. Blanked -In ““t,~ II :II I 31 ,, 1 I uFII IIII II LI I II II IIII II I Time (a) FIG.S.10.—Variation offrequency with timeinabeacon. 
 ... .......281. xiv CONTENTS MECHANICAL SCANNEFIS ..,... 
 and X.Y.; Supervision, M.L. and Y.L.; Project Administration, M.L. and Y.L.; Funding Acquisition, M.L. 
 &IX USES A WIDEBAND INTERMEDIATE 
 TLING TIME  III  DISTORTION CAUSED BY GROUP DELAY DISPERSION  AND IV  REDUCED RELIABILITY WHEN THERE ARE HUNDREDS OF RECEIVERS &URTHER  EACH CHANNEL WILL NEED TO ACCOUNT FOR THE GAIN AND PHASE VARIATION FOR EACH FILTER  INCREASING THE OVERHEADS ON BAND SWITCH 
 INGS IN ANTENNA ARRAY PROCESSING v  3IGNAL 0ROCESSING  %LSEVIER  VOL   NO   PP n   3EPTEMBER   * 7ARD  h3PACE 
 The approach for preventing false tracks on objects not of interest is to actually  develop tracks on all of them but then observe them long enough to classify them as  unwanted. In the case of the bird, one would gather enough detections to improve the  velocity accuracy of the track so that it is clear whether the track is of interest or not.  Thus, one desires to delay the disclosure of a track until enough time has passed to  classify it accurately. 
 The value ofR-can then beincreased by anincrease inpulse length and acorresponding reduction inthe pulse recurrence rate, leaving average power and pulse power fixed attheir highest safe values. Limitations onpulse length areimposed bythe following considera- tions: 1. 2. 
 The signal is then transferred to a computer for pro - cessing, which can include the formation of multiple simultaneous beams (formed  with appropriate aperture illumination weighting) and adaptively derived nulls in the  beam patterns to avoid spatial interference or jamming. Limitations are due to the  availability and cost of analog-to-digital (A/D) converters and to their frequency and  dynamic-range characteristics. Partial implementation is possible by digitizing at sub - array levels only. 
 RATE #&!2  PROCESS n #ELLS WITH AMPLITUDES  GREATER THAN THE #&!2 THRESHOLD ARE LABELED AS DETECTIONS 3IMILAR PROCESSING IS DONE IN THE  $!: AND $%, CHANNELS WITH EXCEPTIONS  AS SHOWN IN  &IGURE  &OR THOSE RANGE 
 INTERVAL RATIO HAS AN IMPROVEMENT FACTOR LIMITATION OF   D" DUE TO STAGGERING 4HE  CURVE GIVES A LIMITA 
 The extent of sea returns modelled in this way can be compared with those in table 7.4. The modelled variation across the upwind and downwind directions is not as extreme as those in the table. However, the expected extent of the sea returns is clearly comparable and the dependence on wind directionis also evident. 
 The false-alarm probability may also be defined as the ratio of  the duration of time the envelope is actually above the threshold to the total time it could have  been above the threshold, or  (2.25) . OJ  O'  E  0 ;- ~ v,  '6  C  ~ t/'ci1  OJ .  n  0  <ii >  C  1 <l THE RADAR EQUATION 25  ----- T1r -------c------1*+1 ___ ______,_.__  Threshold  Time--+- Figure 2.4 Envelope of receiver output illustrating false alarms due to noise. 
 378 THE MAGNETRON AND THE PULSER [SEC. 10.10 thesame material. The tube isfilled toapressure ofalittle lessthan one atmosphere with amixture of75percent hydrogen and 25percent argon. 
 )00 CELLS WHERE 2&) IS DETECTED ARE THEN hREPAIREDv TO PREVENT CORRUPTION OF THE OUTPUT SPECTRUM 4HE FI LTER BANK IS USUALLY  REALIZED BY USING THE FAST &OURIER TRANSFORM &&4  HOWEVER  THE DISCRETE &OURIER TRANSFORM $&4  CAN BE USED WHEN THE NUMBER OF FILTERS IS SMALL !PPROPRIATE WEIGHTING IS EMPLOYED TO REDUCE  THE FILTER SIDELOBES 4HE AMOUNT OF WEIGHTING CAN  BE CHOSEN ADAPTIVELY BY SENSING THE PEAK SIGNAL LEVELS USUALLY MAIN 
 2.3 CLUTTER FILTER RESPONSE   TO MOVING TARGETS The response of an MTI system to a moving target varies as a function of the target’s  radial velocity. For the MTI system described above, the response, normalized for  unity noise power gain, is shown in Figure 2.10. Note that there is zero response  to stationary targets and also to targets at ±89, ±178, ±267,. 
 16 rnntlh is exceeded 8 h/yr and  Wnvel~ngtll, cm 40 mrnfl, ; c~xceeded 2 2 yr.  RADAR CLUTIER 503 ofthediameter, Eq.(13.17).Sincethediameter ofclouddroplets isaboutone-hundredth the diameter ofraindrops, theechoesfromfair-weather cloudsareusuallyoflittleconcern. Itisalsopossible toobtain weakechoes fromadeep,intense fogatmillimeter, wavelengths, butatwavelengths of3cmandlonger,echoesduetofogmaygenerally be regarded asinsignificant. 
 4.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 solution in order to engage, as opposed to nonthreatening targets where a general situ - ational awareness is sufficient and high accuracy is not required. Search.  The two primary search modes are Autonomous Search  and Cued Search . 
 TION LOSS , ON THE MAIN 
 The accuracy with which the range and the velocity can be measured by a particular  waveform depends on the width or the spike, centered at lx(O, 0)12, along the time and the  frequency axes. The resolution is also related to the width of the central spike, but in order to  resolve two closely spaced targets the central spike must be isolated. It cannot have any high  peaks nearby that can mask another target close to the desired target. 
 PULSE BASIS  REPLICATING REFLECTED SIGNALS FROM TARGETS AND CLUT 
 The two-beam technique reduces the returns from very low eleva - tion angles where vehicle traffic (and many birds, bats, and insects) is encountered.  The radar transmits energy using the basic pattern, but uses a higher angle beam  for reception at shorter ranges, and the basic antenna pattern for receiving at longer  ranges. Figure 2.99 shows, underneath the transmitting feed horn, a second receive- only antenna feed horn for the high beam. 
 When extreme structural rigidity or broadband capabilities are required with relatively  light weight, multiple-layer sandwiches of seven, nine, eleven, or more layers may be con­ sidered.  Aircraft radomes, especially those used at supersonic speeds, are subject to mechanical  stress and aerodynamic heating so severe that the electrical requirements or radomes made or  dielectric materials must be sacrificed to obtain sufficient mechanical strength. The radome . 
 TARGET FILTERS.   -4) 2!$!2  Ó°xÎ L 0ROVIDE A RESPONSE OF  
 Allen42 gives several exam - ples of fielded systems using each type. It is essential that the relative locations of the two  antennas be rather precisely known. Advantages and disadvantages of the two types of  InSAR are as follows. 
 -   )NTERNATIONAL -ARITIME /RGANIZATION  WWWIMOORG   h2EVISED RECOMMENDATIONS ON PERFORMANCE STANDARDS FOR RADAR EQUIPMENT v 2ESOLUTION  -3#   )NTERNATIONAL -ARITIME /RGANIZATION  ,ONDON     )NTERNATIONAL !SSOCIATION OF -ARINE !IDS TO .AVIGATION AND ,IGHTHOUSE !UTHORITIES  WWW  IALA 
 3. L 1.03v,  ). (3.2b)  The relative velocity may be written u, = v cos 6, where vis the target speed and (} is the  angle made by the target trajectory and the line joining radar and target. 
 RUPTED 7HEN LIMITERS PREVENT !$ SATURATION  THE SIGNALS ARE LIMITED IN A CONTROLLED MANNER THAT STILL ENABLES GOOD CLUTTER REJECTION ABOUT  OF THE TIME 2ULE  "E WARY OF VIBRATION AND ACOUSTIC NOISE -ANY 2& DEVICES ARE SUSCEPTIBLE  TO BOTH VIBRATION AND ACOUSTIC NOISE !N AIR CONDITIONER FAN BLOWING ON WAVEGUIDE HAS CAUSED DEGRADATION OF IMPROVEMENT FACTOR DUE TO PHASE MODULATION OF SIGNALS 6IBRATIONS CAN CAUSE PHASE MODULATION OF AN OSCILLATOR !COUSTIC NOISE CAN ORIGINATE FROM COOLING FANS  AND VIBRATIONS CAN COME FROM SHIPBOARD OR AIRBORNE RADAR PLAT 
 A rneasurc of tlic cfTcct of tlie load or1 the rnagrietron frequency is the pttllirtg ,figrrre,  defined as the diffcrerlce betwee~l the rt~aximum and minimum frequencies when the phase  angle of the load varies tliroi~gh 360' and tlie magnitude of the VSWR is fixed at 1.5 (or a  rcflcctioti cocrficicrit of 0.20). .I'Ilc pttllitig figure is readily obtained from an inspection of tlie  Rieke diagraln. For the ~nagnetroti whose Rieke diagram is shown in Fig. 
 SESS A LINEAR PHASE 
 15•Half power beamwidth, HPBW (θB)  • Polarization • Sidelobe level  • Antenna noise temperature ( TA)  • Operating bandwidth  • Radar cross section and other signaturesAntenna Parameters 0MAXIMUM  SIDELOBE   LEVELPEAK GAINGAIN (dB)θsPATTERN ANGLEθSCAN  ANGLE HPBW3 dB 0MAXIMUM  SIDELOBE   LEVELPEAK GAINGAIN (dB)θsPATTERN ANGLEθSCAN  ANGLE HPBW3 dB Rectangular dB pattern plot G 0.5G G 0.5G Polar voltage pattern plot. 16•Airborne applications:  > Size, weight, power consumption> Power handling> Location on platform and required field of view > Many systems operating over a wide frequency spectrum > Isolation and interference > Reliability and maintainability> Radomes (antenna enclosures or covers) • Accommodate as many systems as  possible to avoid operational  restrictions (multi-mission, multi-band, etc.) • Signatures must be controlled: ra dar cross section (RCS), infrared  (IR), acoustic, and visible (camouflage) • New antenna architectures and technologies > Conformal, integrated> Digital “smart” antennas with multiple beams> BroadbandRadar Antenna Tradeoffs. 17Radar Range Equation • Quasi-monostatic 2 transmit power (W) received power (W) transmit antenna gain receive antenna gain radar cross section (RCS, m )  effective aperture area of receive antennat r t r erP P G G Aσ= = = = = =RTX PtGt RX PrGrσ Pr=PtGtσAer (4πR2)2=PtGtGrσλ2 (4π)3R4. 
 POLAR COMPONENT OF THE REFLECTION IS SIGNIFICANTLY HIGHER FOR OLD ICE COMPARED TO NEW ICE 4HE PROBLEM IS HOW TO AFFORDABLY DETERMINE THE CROSS 
 Thevalueofremanent magnetization isaffected bytemperature. Tempcrature changes maybeduetomicrowave dissipation intheferriteaswellasambient-temperature variations. Somematerials aremoretemperature-sensitive thanothers,butthematerial cannotalwaysbe selected onthisbasisalone.Garnets aregenerally moretemperature-stable andcanhandle higherpowerthanotherferrimagnetic materials. 
 Puhl .. no. 155. 
 CIVIL MARINE RADAR  22.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 a buoy or a pleasure craft, enhanced by a radar reflector can create significant vertical  lobing effects that can be a problem to the user. In particular, in very calm seas pro - nounced nulls can be experienced, and for users, it can be disconcerting when a target  clearly evident from the bridge window is not visible on the radar display, despite the  apparently good conditions. Since smooth seas can also be associated with mist and fog, vertical lobing effects  can become a significant problem because the reduced visibility means that radar often  becomes the sole method of detecting other vessels. 
 R. E.: Radiation Patterns of a Spherical Luneburg Lens with Simple Feeds, IRE Tra11s.,  vol. AP-6. 
 Rice, S. 0.: Mathematical Analysis of Random Noise, Bell Systern Tech. J., vol. 
 FERENT INCREMENTS IN OUTPUT BECAUSE OF THE NONLINEARITY OF THIS CURVE &OR THIS REASON  RECEIVER CALIBRATION MUST BE PERFORMED OVER A RANGE OF INPUT LEVELS  AND THE NONLINEARI 
 4. If coherence is required from pulse to pulse for second-time-around clutter cancellation, etc. Injection locking has been tried but requires too much power to be attractive. 
 TIME 
 SHIFT CHANGE IF A POWER AMPLIFIER  MUST  BE LESS THAN   $F      RAD    4HE STALO OR COHO FREQUENCY CHANGE IN THE INTERPULSE PERIOD MUST BE LESS THAN   $F rr 
 QUENCY RANGE SUCH AS FROM  TO  '(Z  WHICH IS A TYPICAL FREQUENCY BAND FOR CIVIL #HAPTER     4HIS CHAPTER IS A BRIEF OVERVIEW OF RADAR FOR THOSE NOT TOO FAMILIAR WITH THE SUBJECT &OR THOSE WHO ARE FAMILIAR WITH  RADAR  IT CAN BE CONSIDERED A REFRESHER o  -ICROWAVES ARE LOOSELY DEFINED AS THOSE FREQUENCIES WHERE WAVEGUIDES ARE USED FOR TRANSMISSION LINES AND WHERE  CAVITIES OR DISTRIBUTED CIRCUITS ARE USED FOR RESONANT CIRCUITS RATHER THAN LUMPED 
 M.: Airborne MTI, chap. 18 of" Radar Handbook," M. I. 
 17.12. Slowly varying sine and cosine potentials arefurnished byadata trans- mitter (which can beeither ad-cexcited sine-cosine potentiometer ora two-phase synchro whose output signals arerectified inaphase-sensitive manner). Each ofthese potentials controls the operation ofalinear delay circuit. 
       
 20. 1976.  120. 
 Optical ﬂow methods estimate the motion between two consecutive image frames that were acquired at times tand t+δt. A ﬂow vector for every pixel is calculated. The vectors represent approximations of image motion that are based in large part on local spatial derivatives. 
 Sensors 2019 ,19, 2605 output of this stage is generated by simply taking the intersection of the two results. Figure 6shows how this process converts the reference image in (a) to the ﬁnal output in (e). Figure 6. 
 21.3 the output of the video amplifier is fed to a recorder if optical processing is to be performed and/or to an electronic proces- sor. 27.4 SIGNAL-PROCESSING THEORY The theory of synthetic antenna generation combined with pulse compression is carried out below to show the information theoretic considerations involved and to indicate the operations necessary for achieving both azimuth synthetic antenna generation and pulse compression. A combined range-azimuth resolution func- tion is derived. 
 J. Galejs, “V olume surveillance radar frequency selection,” Proc. of IEEE 2000 Int. 
 Correction of the data is also needed with line-of-sight stabilization using a two-axis  mount. Data stabilization is not necessary if a three-axis mount is used, such as e or f of  Fig. 7.31. 
 VI-2, pp. 351-361. 22. 
 The orbital velocity Vorb is taken to be that of the major waves and is obtained in terms of significant height Hy3 and period "T" from the expression Vorb = TrHy3 /4T" = 0.1*7 (13.10) The approximate dependence on wind speed U was found by substituting Hy3 = 3hrms from Eq. (13.6), assuming a fully developed sea, and T from Eq. (13.5). 
 This results in the synthetic aperture radar having a two-way antenna pattern  E  Focused SAR Fipre 14.3 Comparison of the resolution of a  synthetic aperture radar and a radar with a con-1,.~~~~·~~~~~~~~~~~  10 100 ventional antenna, assuming an X -band antenna  Ronge. km with dimension D == 3. m. 
 29.18 to 29.23. 37. T. 
 5.2SEQUENTIAL LODING Theantenna pattcrncommonly employed withtracking radarsisthesymmetrical pencilbeahl inwhichtheelevation andazimuth beamwidths areapproximately equal.However, asimple pencil-beam antenna isnotsuitable fortracking radarsunlessmeansareprovided fordeter­ miningthemagnitude anddirection ofthetarget'sangular position withrespecttosome rcference direction, usuallythea"isoftheantenna. Thedifference between thetargetposition andthereference direction istheallglllar error.Thetracking radarattempts toposition the antenna tomaketheangularerrorzero.Whentheangularerroriszero,thetargetislocated alongthereference direction. Onemethod ofobtaining thedirection andthemagnitude oftheangularerrorinone coordinate isbyalternately switching theantenna beambetween twopositions (Fig.5.1).This iscalledloheswitching, seqllential switching, orsequential lobing.Figure5.laisapolarrep­ resentation oftheantenna beam(minusthesidelobes) inthetwoswitched positions. 
 43.Johnson, R.c.:OpticalScanners, chap.3of"Microwave Scanning Antennas, vol.I,"R.C.Hansen (cd.),Academic Press,NewYork,1964. 44.Foster, 1.S.:AMicrowave Antenna withRapidSaw-Tooth Scan,CmlL/diel/l J.ofPhys.,vol.36, pp.1652-1660, 1958. 45.Martindale, J.P.A.:LensAerialsatCentimetric Wavelengths, J.Brie.IRE,vol.13,pp.243-259, May,1953. 
 The test parameters are consistent with parameters as shown in Table 4. With 10% echo data adopted, Figure 18shows the test system and target scene and distribution of targets within the box. The imaging results are as shown in Figure 19. 
 I. Katz and L. M. 
 QUENCY TELECOMMUNICATIONS SYSTEMS v %33! 4ECH 2EPT  )%2  )43!    53 $EPARTMENT OF  #OMMERCE    ! , "ARGHAUSEN  * 7 &INNEY  , , 0ROCTOR  AND , $ 3C HULTZ  h0REDICTING LONG 
 Fast recovery is required to minimize  desensitization in the range gates following the transmitted pulse. R/Ps can be imple - mented with a gas discharge tube, in which a gas is ionized by high-power RF. A diode  limiter can be used instead of or in conjunction with the gas discharge tube. 
        
 waveguide there isabasic relation between thewidth oftheguide and the angle ofincidence ofthe plane waves into which the simpler waveguide modes can beresolved. The longer the wavelength and the narrower theguide, the larger the angle aaccording toarelation which forvery wide guides reduces toa=h/2u. But if,inour model sketched inFig. 
 An L1minimization problem is also known as Basis Pursuit. The theory of Lagrange multipliers indicates that we can solve an unconstrained problem that will yield the same solution, provided that the Lagrange multipler is selected correctly. The unconstrained problem is known as LASSO or L1regularization [ 13]. 
   LOBE DISCRETE REJECTION LOGIC &OLLOWING DETECTION EDITING  RANGE AND VELOCITY AMBI 
 GRAZING 
 24. C. J. 
 BASED $2&- JAMMER   %##- TECHNIQUES FOR 3!2 CAN BE DIVIDED INTO I  ANTENNA 
 The formerarepredictable, butthelatterarenotandcanonlybedescribed instatistical terms. 'Ii Examples ofsystematic errorsinclude(1)mutualcoupling between theelements ofanarray, (2)aperture blocking inreflector antennas duetothefeedanditssupports, (3)dirrraction at thestepsinazoned-lens antenna, and(4)periodicities included intheconstruction ofthe antenna. Random errorsinclude(1)errorsinthemachining ormanufacture oftheantenna as aconsequence ofthefiniteprecision ofconstruction techniques, (2)RFmeasurement errors incurred inadjusting anarray,(3)wall-spacing errorsinmetal-plate lenses,(4)random distor­ tionoftheantenna surface, and(5)mechanical orelectrical phasevariations causedby temperature orwindgradients acrosstheantenna. 
 A nonsymmetrical waveform is . TABLE 10.1 Summary of Performance of Various Pulse Compression Implementations Phase-coded Nonlinear FM Linear FM Passive Active Passive Active Passive Active Provides full range coverage.Limited range cov- erage per active correlation pro- cessor.Provides full range coverage.Limited range cov- erage per active correlation pro- cessor.Provides full range coverage.Limited range cov- erage per active correlation pro- cessor.Range coverage Multiple doppler channels required, spaced by (1/7) Hz. Covers any doppler up to ± 5/10, but a range error is introduced. 
 TION FILTER  !N 3INCE $FD B   $FD M  THE CONSTRAINT ON BISTATIC SIGNAL PROCESSING TIME IS  SLIGHTLY LESS THAN THE EQUIVALENT MONOSTATIC TIME !S IN THE MONOSTATIC EQUATION  THE TRANSMITTING AND RECEIVING PATTERN PROPAGATION  FACTORS  &4 AND &2  EACH CONSIST OF TWO TERMS THE PROPAGATION FACTORS   &g4 AND &g2   AND THE ANTENNA PATTERN FACTORS   F4 AND F2  RESPECTIVELY 4HE  ANTENNA PATTERN FACTORS ARE  THE RELATIVE STRENGTH OF THE FREE 
 One  method is based on exploiting the advantages of some new invention, new technique,  new device, or new knowledge. The invention of the microwave magnetron early in  World War II is an example. After the magnetron appeared, radar design was different  from what it had been before. 
 In a dirct with i'c~rlq)li~tc trapping of the  elcctromagnctic energy. tlic cylindrical spreading of tlic energy rndiatcc' by a poillt source  rcsiilts in the power density decreasing as R - '. where R = range, instead of R - as wit 11 free 3. 
 2.2.6 Leigh Light During 1941 and early 1942 it was found that despite the improved performance of LRASV there were great dif ﬁculties in pressing home an attack at night. This was because sea returns tended to limit the minimum ASV range to about 1 mile and at night targets were then lost as the aircraft approached closer, as there was no way ofilluminating the target. U-boats were exploiting this weakness by mainly surfacing at night. 
 Z. Peebles, Jr., “Conopulse radar,” IEEE Trans ., vol. AES-14, pp. 
 Whenthisoccurs,the narrowsectorinthedirection ofthejammer willappearasaradialstrobeontherPIdisplay.. Thedirection tothejammer canbedetermined, butitsrangeandtherangcsofanytargets masked bythenoisestrobeisnotlikelytobeknown.Ifnoiseentcrstheradarviathcantenna sidelobes, theentiredisplaycanbeobliterated andnotargetinformation ohtained. Thusitis essential thatnoisebeprevented fromentering thereceivcr viatheantenna sidclobes. 
 Swerling, “Probability of detection for fluctuating targets,” IRE Trans ., vol. IT-6, pp. 269–300,  April 1960. 
 Sampling   (50 MHz) 7. Sampled complex   baseband signal–75 MHz –150 MHz ch25.indd   6 12/20/07   1:39:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 ROUTE TRACKING OF COMMERCIAL AIRCRAFT  AIR SURVEILLANCEAIR DEFENSE  NAVIGATIONAL ASSISTANCE  TACTICAL CONTROL  AND TACTICAL BALLISTIC MISSILE 4"-  DEFENSE 4HE !.403 
 J. M. Headrick. 
 J. C. Hubbert, G. 
 The nuclear reactor design re- . FIG. 22.15 Baseline prime power systems: deployed configurations.61 quires engineering development. 
 ING LOBES ARE LOCATED AT   COS COS COS COSAAL AALXS YS 
 71 -77. January, 1957.  19. 
 Natl.Calit:Proc..-IaO/wl/l. Electrollies (Dayton, Ohio),pp.286-290, 1958. 61.Siegel,K.M.,H.A.Alperin, R.R.Bronski, J.W.Crispin, A.L.Moffett. 
 4 Loci of constant normalized radial velocity Vr/Vg as a func - tion of aircraft range-to-height ratio R/H and azimuth angle y ch03.indd   5 12/15/07   6:02:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 
 The  effect of multiple beams is generated with this feed, but only two receivers plus a phase detector  are needed to determine angular location." 35 Sn order to obtain wide coverage in elevation  angle a parabolic-torus reflector is employed rather than a section of a paraboloid. A curved  piece of wavegiiide with radiating slots acts as the feed. The transmitter is fed into one end of  the waveguide feed wllose slots are designed to produce a number of contiguous bearns in  elevation witli atnplitudes co~itrolled so as to produce a cosecant-squared radiation patterrl. 
 M. Hunter. and N. 
 Young, and L. A. Hyland. 
 TOR ANTENNAS ARE EXTENSIVELY DISCUSSED IN THE LITERATURE n ! BASIC GEOMETRY IS SHOWN  IN &IGURE  A  WHICH ASSUMES A PARABOLIC REFLECTOR SURFACE OF FOCAL LENGTH  F WITH   A FEED AT THE FOCAL POINT )T CAN BE SHOWN FROM GEOMETRICAL OPTICS CONSIDERATIONS THAT  A SPHERICAL WAVE EMERGING FROM THE FOCAL POINT   &  AND INCIDENT ON THE REFLECTOR IS  TRANSFORMED  AFTER REFLECTION  INTO A PLANE WAVE TRAVELING IN THE POSITIVE  Z DIRECTION  &IGURE B  !LTHOUGH REFLECTORS ARE COMMONLY ILLUSTRATED WITH A ROUND OUTLINE OR RIM AND A CEN 
 Height isestimated directly from theface ofthescope. The two signals from asingle target (e.g., Aand B)always appear atthesame range.. SEC. 
 (13.11), is sketched on the figure. The large spectral spike appearing in the center of the display is no doubt due to a wave breaking in or close to the measurement cell. The doppler velocity for this spike suggests a peak scatterer velocity of about half the wind speed, which would correspond to the group velocity of the longest waves on the surface. 
 Figure 4. Faraday rotation (FR) estimates as a function of signal amplitude. PolSAR: polarimetric spaceborne synthetic aperture radar. 
 The secondary reflector may also be used toPATTERN EFFICIENCYSLOPE DIFFERENCESLOPE DIFFERENCE EDGE TAPER (dB)EFFICIENCY (dB) NORMALIZED SLOPE . TABLE 6.1 Monopulse Feedhorn Performance relocate the feed close to the source or receiver. By suitable choice of shape, the apparent focal length can be enlarged so that the feed size is convenient, as is sometimes necessary for monopulse operation. 
 (If the radar is on a rapidly moving platform, the clutter might also be  decorrelated as the radar resolution cell views a different patch of clutter.)  Receiver detection criteria. In Chap. 2 the receiver detection criterion was based on the  methods of Marcum and Swerling. 
 559-563, 25-28 Oct., 1977. IEE  (London) Conference Publication no. 155. 
 Stiles. L. F. 
 Elec- tronic beam-scanning phased array tracking radars may track multiple targets by sequentially dwelling upon and measuring each target while excluding other echo or signal sources. Because of its narrow beamwidth, typically from a fraction of 1° to 1 or 2°, a tracking radar usually depends upon information from a search radar or other source of target location to acquire the target, i.e., to place its beam on or in the vicinity of the target before initiating a track. Scanning of the beam within a lim- ited angle sector may be needed to fully acquire the target within its beam and center the range-tracking gates on the echo pulse prior to locking on the target or closing the tracking loops. 
 Near-ﬁeld radar imaging via compressive sensing. IEEE T rans. Antenna Propag. 
 Although some might think these should have disappeared  along with the old radio vacuum tube, there have been many HF, VHF, and UHF radars  that successfully operated with grid-control tubes. Often with such radars, it would cost  more to replace them with solid-state transmitters, and there might be little gained by  doing so. The grid-controlled tube known as the constant efficiency amplifier (CEA)  ch10.indd   25 12/17/07   2:19:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 It is noted that the frequency diversity and the  logic OR provide an improvement of the blanking probability; this is due to the  different shapes of the antenna patterns at the two slightly different carrier frequen - cies. Figure 24.5 also presents the probability of blanking a useful target ( PTB)  received by the main antenna beam. The probabilities are estimated via 200 inde - pendent Monte Carlo simulations. 
 Conventional microwave antenn.as cannotgenerate radiation pallerns withsidelobes as lowascanbeobtaineq byanarrayantenna, especially anonscanning array.However, whena planararrayiselectronically scanned, thechangeofmutualcoupling thataccompanies a changeinbeamposition makesthemaintenance oflowsidelobes moredifficult. Ifanarrayhassomemargininperformance topermitgraceful degradation, itislikely thatthismarginwillbeeliminated duringtheprocurement process ifthecostoftheradar escalates. Eveniftheradarisdelivered withmarginforgraceful degradation, itislikelythat aftersometimeinoperation itwillalwaysbeatthedegraded levelbecauseofadesiretokeep maintenance coststoaminimum. 
 These are usually suppressed  for thermal noise by constant false alarm rate thresholding, coincidence detection,  and post-detection integration with frequency agility. Clutter false alarms are sup - pressed by adaptive aperture tapering, low-noise front-end hardware, wide dynamic  range A/Ds, clutter rejection filtering (including STAP), pulse compression sidelobe  suppression, doppler filter sidelobe control, guard channel processing, radome reflec - tion lobe compensation, angle ratio tests (see Figure 5.37 and the “fringe region” for  an example angle-ratio- test), and adaptive PRF selection. FIGURE 5.15  Typical MPRF processing ( adapted8; courtesy SciTech Publishing ) ch05.indd   17 12/17/07   1:26:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 39-44  December, 1973.  146. Brennan, L. 
 In this figure, the active channel region FIGURE 11.19  X-band two-stage power amplifier MMIC showing paral - lel combination of FET cells in the output stage. This example was fabri - cated on 100 µm- thick GaAs substrate. The RF lines are microstrip-format   TEM-mode transmission lines. 
 34.Middleton, D.,andD.VanMeter:Detection andExtraction ofSignalsinNoisefromtheViewpoint of Statistical Decision Theory,J.Soc. Ind. Appl.Math.,vol.3,pp.192-253, December, 1955,andvol.4, pp.86-119,June,1956:, 35.Bussgang, J.J.,andD.Middleton: Optimum Sequen,tial Detection ofSignalsinNoise,IRETrans., vol.IT-I,pp.5-18,December, 1955. 
 This is a flat plate-glass window in the cone of a cathode-ray tube aligned to be  parallel to the tube It allows slide or film information to be projected onto the  358INTRODUCTION TORADAR SYSTEMS Thestoragetubeusestwo electron beamsgenerated byseparate electron guns.Oneisa writingbeam.Theotherisafloodbeamthatpermits abright;persistent displayofthe information carriedbythewritingbeam.Thewritingbeamdoesnotimpinge directlyonthe viewingscreenasinaconventional CRT.Itstrikesastoragemesh,mounted justbehindthe screen,madeupofathinfilmofinsulator material deposited onametallic backingelectrode. Theinsulator, whichisthestoragemedium, isilluminated continuously bya..flood"beam. Whenilluminated bythewritingbeam,chargeisstoredontheinsulator surfacebecause of itssecondary emission characteristics. 
 ( b) Image with ﬂipping. ( c) Image with brightening. ( d) Image with sharpness. 
 ING DISCUSSED LATER IN THIS CHAPTER  4HIS IS BECAUSE THE ADAPTIVE FILTER WILL ADJUST TO THE RECEIVED SIGNALS AND OPTIMIZE CLUTTER CANCELLATION 7ITHOUT ADAPTIVE ADJUSTMENT  &IGURE  SHOWS THE IMPROVEMENT FACTOR FOR SINGLE 
 Finally, Fig. 15.30 shows the average SCR improvement of the 68 dB Chebyshev doppler filter bank as well as the optimum curve (from Fig. 15.19) as a function of the relative spectrum spread of the clutter. 
 ART FOR CONVENTIONAL ALTIMETERS 4HE DELAY 
 IlIterllatiollal COllferellce allRadar l're.H'/lt (lIldFutl/re.Oct.13-25.1973.1EE(London) Conference Publication no.105.pp.213220. 31.Croncy. 1..1\.Woroncow. 
 LAYER DISAPPEARS  THE % AND & REGIONS EXPERIENCE A SUBSTANTIAL DECREASE IN IONIZATION  AND THE EQUATORIAL AND POLAR REGIONS ARE MORE PRONE TO LARGE 
 Additional feeds displaced from the focal point form additional beams  at angles from the axis (see Eq. 12.21). Thus, one can employ a multiple feed array with  appropriate electronics to feed a reflector and provide either multiple displaced beams  or electronic beam switching, i.e., beam scanning to discrete angles. 
 2. Control the phase and amplitude errors that contribute to the random sidelobes. Of the two, controlling errors fundamentally limits sidelobe performance. 
 NOISE RATIO     D"  FROM ' 6 4RUNK AND 0 + (UGHES . Ç°£È  2!$!2 (!.$"//+  )F THE NOISE SAMPLES ARE CORRELATED  NOTHING CAN BE DONE TO THE BINARY INTEGRATOR TO  YIELD A LOW  0FA 4HUS  IT SHOULD NOT BE USED IN THIS SITUATION (OWEVER  IF THE CORRELATION  TIME IS LESS THAN A BATCHING INTERVAL  THE BATCH PROCESSOR WILL YIELD A LOW  0FA WITHOUT  MODIFICATIONS 4ARGET 3UPPRESSION  4ARGET SUPPRESSION IS THE LOSS IN DETECTABILITY CAUSED BY OTHER   TARGETS OR CLUTTER RESIDUES IN THE REFERENCE CELLS "ASICALLY  THERE ARE TWO APPROACHES TO  SOLVING THIS PROBLEM   REMOVE LARGE RETURN FROM THE CALCULATION OF THE THRESHOLDn OR    DIMINISH THE EFFECTS OF LARGE RETURNS BY EITHER LIMITING OR USING LOG VIDEO 4HE TECHNIQUE THAT SHOULD BE USED IS A FUNCTION OF THE PARTICULAR RADAR SYSTEM AND ITS ENVIRONMENT 2ICKARD AND $ILLARD  PROPOSED A CLASS OF DETECTORS  $+  WHERE THE  + LARGEST SAMPLES  ARE CENSORED REMOVED  FROM THE REFERENCE CELLS ! COMPARISON OF  $ NO CENSORING   WITH $ AND $ FOR A 3WERLING  TARGET AND A SINGLE SQUARE 
 '(Z    MEASUREMENTS AND ANALYSIS 7IND 
 In [14], it is shown that L1can reconstruct the targets with the underestimated amplitudes. Some missed detections are also introduced in the results of L1regularization. In addition, with less azimuth measurements, the resolution of the subaperture is reduced. 
 Lab. Electron. Tech. 
 ING v IN )%% )NT 2ADAR #ONF 2EC  ,ONDON  /CTOBER n    $ $ (OWARD  h%NVIRONMENTAL EFFECTS ON PRECISION MONOPULSE INSTRUMENTATION TRACKING RADAR AT   '(Z v IN )%%% %!3#/.  2EC  /CTOBER   2 * -C!ULAY AND 4 0 -C'ARTY  h-AXIMUM 
 NOISE POWER RATIO IN THE RANGE 
 LIKE COMPONENT WILL NOT CANCEL IN THE -4) SYS 
 Using a constant-velocity airborne radar, the received spectrum from a stationary  target has lines that are doppler-shifted proportionally to the radial velocity between the  radar platform and the target. The two-way doppler shift is given by fd = (2VR/l)cos(y0),  where l is the radar wavelength, VR is the radar platform speed, and y0 is the angle  between the velocity vector and the line of sight to the target. (Note that the relative  radial velocity (range rate) to the stationary target is Vrelative  = −VR cos(y0), which makes  the later equation for doppler shift consistent with the one presented at the beginning  of the chapter.) Illustrated in Figure 4.1 is the received pulsed spectrum with returns  from distributed clutter, such as the ground or weather, and from discrete targets, such  as aircraft, automobiles, tanks, etc. 
 The summation is correct if and only if the inequality 0 ≤ˆtg(p) T<1 holds, otherwise for particular rand p,kincreases, and the procedure is repeated until k=K+( kmax−kmin)−1, then for particular rand k,pincreases, and the procedure is repeated until p=N−1, then for particular p and k,rincreases, and the procedure is repeated until r=R−1, which is the end of the asteroid’s ISAR signal formation. Only one microburst is considered. The ISAR signal microburst in the main pulse sequence, reemitted by the asteroid, after preliminary signal processing (signal detection and de-dispersion) is recorded in two-dimensional coordinates, time tand frequency fr. 
 Frequency  Figure 4.7 Frequency response of the single delay-line canceler; T = delay time = lfP.  MTIANDPULSEDOPPLER RADAR107 reasonable physical lengthsincethevelocityofpropagation ofacoustic wavesisabout10-5 thatofelectromagnetic waves.Afterthenecessary delayisintroduced bytheacoustic line,the signalisconverted backtoanelectromagnetic signalforfurtherprocessing. Theearlyacoustic delaylinesdeveloped duringWorldWarnusedliquiddelaylinesfilledwitheitherwateror mercury.1Liquiddelaylineswerelargeandinconvenient touse.Theywerereplaced inthe mid-1950s bythesolidfused-quartz delaylinethatusedmultiple internalreflections toobtain acompact device.Theseanalogacoustic delaylineswere,inturnsupplanted intheearly19705 bystoragedevicesbasedondigitalcomputer technology. 
 SECTS THE PARALLEL TO THE FLAT GROUND AT GRAZING ANGLE  X 4HE DIFFERENCE IN THE PHASES OF  THE ECHOES RECEIVED FROM THE POINT TARGET OBSERVED BY THE TWO ANTENNAS IS NOW   $FPY L N,SIN    7 E CONSIDER THE QUANTITY   $$ $FF FP LYY x 
 71  Lens tolerances.1 ·2 In general, the mechanical tolerances for a lens antenna are less severe than  for a reflector. A given error in the contour or a mechanical reflector contributes twice to the  error in the wavefront because of the two-way path on reflection. Mechanical errors in the lens  contour, However, contribute but once to the phase-front error. 
 ( c) Trihedral. ( d) Top-hat. Figure 2. 
 POINT QUANTIZATION 3PACECRAFT DESIGN LIFE IS FIVE YEARS (* 
 At 10 ktn altitude Ci is approxi-  niatcly 10 in ' -', An S-band radar with one degree beamwidth and 1 14s bulsewidth  viewing a turbulent rnediuni with tl = lo-'' m-' yields a radar cross section at 10 km of  about 3 x 10- * m2. TIILIS, angel echoes frorqclear-air turbulence are not likely to bother most  radars.  Other angel echoes. 
 —Figure 13”20 illustrates acommon method offixing the absolute potential taken byapoint inthe circuit during extreme excursions ofthe signal inone direction. Inthe absence ofthe diode, theaverage potential ofpoint Amust beVO,since Rfurnishes the only d-cconnection. When the diode isplaced inthe circuit, itprevents A from swinging more negative than VO,sothat V,may bethought ofasa base with respect towhich theentire waveform ispositive. 
 A true(logarithmic characteristic cannot be maintained down to zero iriput since  I..,,~ 4 - rn as vin --* 0. At some point the receiver characteristic must deviate from logarithmic  and go through the origin. The practical logarithmic receiver will have a law given by  I*,,, = u log (1 + hvin). 
 This technique is particularly con- venient when a CFA power booster is added to an existing pulsed oscillator MTI radar system; simply by changing the point at which the RF sample is taken for locking the existing coho, the added CFA is not required to have tight pulse-to- pulse phase stability. A digital equivalent of the locked coho has also been used. The phase of the transmitter is simply measured on each pulse, and the proper correction is made on the received signals in the signal processor. 
 Brejcha, A. G., L. H. 
 64. Schensted, C. E., J. 
    VOL   -AY   NOW UNLIMITED DISTRIBUTION   3 4 #OST  h-EASUREMENTS OF THE BISTATIC ECHO AREA OF TERRAIN AT 8 
 It is a paradox that a noise parameter is usually the first characteristic specified for a radar receiver, yet few radars employ the lowest-noise receiver available because such a choice represents too great a sacrifice in some other characteristic. Cost is rarely a consideration in rejecting a lower-noise alternative. A reduc- tion of requirements for antenna gain or transmitter power invariably produces cost savings far in excess of any added cost of a lower-noise receiver. 
 ETERS TO BEST MEET THE PRESCRIBED NEEDS AT A GIVEN TIME $EPENDING ON THE FINAL COSTS OF DEPLOYMENT AND OPERATION  #!3! NETWORKS MAY BE DEVELOPED ONLY AROUND CRITICAL AREAS SUCH AS URBAN AREAS  AIRPORTS  ETC 2APID 3CAN 0HASED !RRAY  2ADAR  $OPPLER WEATHER RADARS THAT USE PHASED ARRAY  ANTENNAS AND COMPLEX WAVEFORM DESIGN MAY BE APPLIED TO SOME OF THE MORE DIFFICULT RADAR METEOROLOGY OBSERVATIONS 4HE USE OF MULTIPLE DOPPLER RADARS HAS PROVIDED DRA 
 £x°£-i>Ê ÕÌÌiÀ  iÜÃÊ °Ê7iÌâi .AVAL 2ESEARCH ,ABORATORY RETIRED  £x°£Ê  /," 1 /"  &OR AN OPERATIONAL RADAR  BACKSCATTER OF THE TRANSMITTED SIGNAL BY ELEMENTS OF THE  SEA SURFACE OFTEN PLACES SEVERE LIMITS ON THE DETECTABILITY OF RETURNS FROM SHIPS  AIR 
 E  <l \ I ' / ' /  \  \ ....__  I  I Rodar  echo  ,...-,, / pulses  I _,,.,.,...-- / _.---\ I  Time  \ ' / , __ (a)  (b)  {c) Figure4.22 (a) Blind speed in an MTI radar.  The target doppler frequency is equal to the  prf. (b) Effect of blind phase in the l channel,  and (c) in the Q channel. 
 THE 
 It is also possible to utilize  a second electron gun in the CRT to minimize the amount of time taken from the radar to  insert the synthetic data. Another method for achieving the necessary time to display alpha­ numeric da(a is to store the video in a shift register and then read it out at a higher rate.  The CCD, or charge coupled device, is one possibility as a shift register. 
 Another approach thatdepends onadditional antenna feeds,ordegrees offreedom, employs amonopulsetrackerwithadifference patterncontaining asecondnull whichisindependently steerable. Thisnullismaintained inthedirection oftheimage,as computed bySnell'slawforthemeasured targetrange.Theuseoftheclassical maximum likelihood solution fortheoptimum double-null difference pattern resultsinrelatively large sidelobes atthehorizon andatanglesbelowtheimage.Byslightlysacrificing theaccuracy of angletracking (duetolessslopesensitivity), lowersidelobes canbeachieved. Suchapattern whichsacrifices slopesensitivity forlowersidelobes hasbeencalledatempered double-null durerellce pattern.48 Thetempered double-null ismoresuitedtomechanically steeredtrackers thantoehased­ a~~since itisbasically anullbalance technique thatdoesnotachievefullaccuracy untilitgoesthrough asettling process. 
 given by  where fd = doppler frequency shift and L). = relative (or radial) velocity of target with respect  to radar. The doppler frequency shift is  lerc, = ralslll fr~q~~e~~cy i~id c = velocity of propagatio~l = 3 X 10' [nh 1ffd in  hertz. 
 TO 
 24,Chap. 8)leads tocertain positive statements. First, therapid- ityofthefluctuations isdetermined bythebandwidth @oftheamplifier. 
 (4.13). (This is analogous to generating N  irldcpendetlt bcanls from an N-clenle~lt array by use of the Blass multiple-beam array as in  Fig. 8.26.) Wherl generating the filter bank by digital processing it is not necessary literally to  subdivide each of tlie N taps. 
 37. Hammer. I. 
 TYPE MODULATOR 3INCE OTHER THAN VACUUM TUBES CAN BE USED AS THE SWITCH IN AN ACTIVE 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 24.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 required because of the limited degree of clutter, chaff, and jammer suppression practi - cally achieved by coherent devices, so that the cancellation residue may still be a sig - nificant source of false alarm. Among the noncoherent devices, it is worth mentioning  the CFAR detector141–145 and the pulse-width discriminator, this latter being effective  against pulsed jammers. 
 440 INTRODUCTION TO RADAR SYSTEMS  45. Hynes, R., and R. E. 
 The glint error can be reduced by  averaging the independent measurements obtained with frequency agility. (The depth D as  seen by the radar might be less than tlie geometrical measurement of target depth if the  extremities of the target result in small backscatter.)  The improvernerlt 1 in the tracking accuracy when the frequency is changed pulse-to-pulse  is approximately3'  where Bfa = the frequency agility bandwidth, D = target depth, c = velocity of propagation,  B, = glint bandwidth, and f, = pulse repetition frequency. (The approximation holds for large  prf's and for the usual glint bandwidths which are of the order of a few hertz to several tens of  For example. 
 Conversely, choos - ing values of Mf that contain large factors of 2N creates relatively large spurious spacing.  For example, using a 640 MHz clock allows the generation of frequencies at multiples of  10 MHz with all the spurious components occurring at multiples of 10 MHz. The impact of DDS spurious signals on radar performance depends on the nature  of the spurious signals and the type of radar processing involved. 
 Detectionranges against submarines were comparable with those observed following tuning by TRE in the earlier trial [ 13]. This improvement was attributed to better experience of the RAF maintainers, combined with the provision of improved ground test equip-ment. This CCDU report also included detailed operating instructions for the radar, showing how to tune the system in the air and manipulate the controls when homing. 
 If the clutter spread cr11mdue to the  platform motion combines with the clutter spread <le due to internal clutter motion such that  the total standard deviation <rr of the clutter spectrum is o-} = a-; + o-:m, the MTI improve­ ment factor for the total clutter spectrum is  (4.39)  The solid curves of Fig. 4.35 plot this equation for a three-pulse delay~line canceller (N1 = 2).  If the widening oft he spectrum is a result of the radar platform·s velocity, its effects can be  mitigated by making the radar antenna appear stationary. 
 III Aircraft for Sea Search, ASWDU Report 45/17. June 1945 (TNA AIR 65/177) [21] ASV Mk. III in Sunderland (Second Report) —Production Installation, CCDU Trial Report 44/59, April 1944 (TNA AIR 65/126) [22] A.S.V. 
 PHASE  -4) FILTER DESCRIBED BY  :VEREV 4HE FOUR ZEROS ARE LOCATED ON THE  : 
 Natl. Conf.  Aeronaut. 
 It is in the  coming text referred to as an error cube.  The polarimetric in and output gates, which [ Sm]  and/or ah, av and bh, bv demonstrates, are in the foremost 4 corners of the cube.  The front  surface of the cube is therefore identified as the Radar plane. 
 13.51, where the switches represent double-sided clamps that are _ .. FIG.13.51 .—Pre-time-base resolution method ofPPI ssnthesis. opened during thesweep interval. 
 persistence required in a cathode-ray-tube screen depends upon the application. A long-  persistence screen such as the PI9 is appropriate for PPI presentations where the frar~le times  are on the order of several seconds. On the other hand, where no persistence is needed, as when  the frame time is less than the response time of the eye (0.1 s or less), a PI phospl~or niight he  used. 
 The number ofother independent variables, yetunmentioned, which affect the amount ofgain realized through storage isappallingly large. The more prominent ofthese must bediscussed briefly, ifonly tosuggest the scope ofthegeneral problem treated comprehensively inVol. 24. 
 Because of the largedifferences in the various dimensions of the radiation pattern, ﬁgure 1.2 isnecessarily distorted.Although the radiated energy is concentrated or focused into a relatively narrow main beam by the antenna, similar to a beam of light from a flashlight,there is no clearly defined envelope of the energy radiated. While the energy isconcentrated along the axis of the beam, its strength decreases with distancealong the axis. The strength of the energy decreases rapidly in directions awayfrom the beam axis. 
 14.42  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 sharply swept tail fins. The tail fins are canted out as well as being swept aft, and the  wings are also sharply swept. Although Lockheed managed to produce a supersonic  SR-71 airframe using exotic materials, the low RCS demanded of the F-117 required  a subsonic airframe. 
 86 HOW RADAR WORKS  in Fig. 4, or one of its several variations, such as in  Fig. §. 
 4IME !DAPTIVE 0ROCESSING v ,ONDON )%%   % & +NOTT  * & 3HAEFFER  AND - 4 4ULEY   2ADAR #ROSS 3ECTION  ND %D  2ALEIGH  .#  3CI4ECH    % / "RIGHAM   4HE &AST &OURIER 4RANSFORM AND )TS !PPLICATIONS   %NGLEWOOD #LIFFS  .* 0RENTICE  (ALL    % $ +APLAN   5NDERSTANDING '03  0RINCIPLES AND !PPLICATIONS   .ORWOOD  -! !RTECH  (OUSE    2 7 "AYMA AND 0 ! -C)NNES  h!PERTURE SIZE AND AMBIGUITY CONSTRAINTS FOR A SYNTHETIC APERTURE  RADAR v IN 0ROC  )NTERNATIONAL 2ADAR #ONFERENCE  PP n 2EPRINTED IN +OVALY    & - (ENDERSON AND ! * ,EWIS EDS    0RINCIPLES  AND  !PPLICATIONS  OF  )MAGING  2ADAR     .EW 9ORK 7ILEY    # /LIVER AND 3 1UEGAN   5NDERSTANDING 3YNTHETIC !PERTURE 2ADAR )MAGES   .ORWOOD  -!  !RTECH (OUSE    & * (ARRIS  h/N THE USE OF WINDOWS FOR HARMONIC ANALYSIS WITH THE DISCRETE &OURIER TRANSFORM v  0ROCEEDINGS OF THE )%%%  VOL   NO   PP   *ANUARY   $ "ARTON  2ADAR 3YSTEMS !NALYSIS AND -ODELING  .ORWOOD  -! !RTECH (OUSE  . £Ç°ÎÈ  2!$!2 (!.$"//+   2 * 3ULLIVAN  ! $ .ICHOLS  2 & 2AWSON  # 7 (ANEY  & 0 $AREFF  AND * * 3CHANNE  *R   h0OLARIMETRIC 8,# 
 Ground Airborne Multistatic Radar, pp. 3/1-3/3, London, 1981. 83. 
 49. Pickering, A. H.: Electronic Tuning of Magnetrons, Microwave J., vol. 
 (;amble. W. L.. 
 ING 4HE RIGHTMOST PLOTS REPRESENT THE USE OF  RANGE GATE OVERLAP  S S   SG  4HE  MAXIMUM PULSE MATCHED FILTER OUTPUT AS  A FUNCTION OF RETURN DELAY IS SHOWN IN TERMS OF  RELATIVE VOLTAGE AND POWER 4HE hVOLTAGEv PLOT SHOWS THE CUMULATIVE EFFECT OF CONVOLV 
 vol.41.pp.77XO.Fenruary. 1971. Xl).RanineI'. 
 Phasequantization cancausealossinantenna gain,anincrease inthermssidelobe level,the generation ofspurious sidelobes, andashiftinthepointing ofthemainbeam.Theeffectof quantized phaseshiftersontheradiation pattern issimilartotheeffectofrandom errors. Thegainofanarrayantenna withameansquarephaseerrorb2initsaperture illumina­ tionisapproximately (8.30) (8.31)whereGn=no-error gain.Thisfollowsfr'omEq.(8.28)withPe=L~2=O.and(j2small.For aquantized phaseshifterconsisting ofBbits,thephaseerror(jisdescribed byauniform probahility densityfunction extending overaninterval±rr/2R.FromSec2.4themeansquare phaseerrorfortheuniform probability density function is~2=rr2j3(22B).Substituting into Eq.PUO),thelossofgainisfoundtobe1.0dBforatwo-bit phaseshifter,0.23dBfora three-bit phaseshifter.and0.06dBforfourbits.Onthebasisofthelossingain,athree-or four-bit phaseshiftershouldbesatisfactory formostapplications. Phasequantization errorsalsoresultinanincrease inthermssidelobelevelandinthe peaksidelobe level.Withtheassumptions that(1)theenergylostbythereduction inmain heamgainshowsupasanincrease inthermssidelobe level,(2)theelement gainisthesamefor themainheamandthesidelobes(withintheregionofspacescanned bythearray),(3)an allowance ofonedBforthereduction ingainduetotheaperture illumination. 
 Figure 11.14 shows the relationship between the RCS and the mass of an insect, with the variation of a water droplet shown for comparison. Similar comparisons have been made for both birds and insects. The following values have been reported for the RCS of a man:16AXIS OF CORNER REFLECTOR TO RADARECHO LEVEL (dB) . 
       
 CM WAVELENGTH  PROVIDED THE FIRST SYNOPTIC COVERAGE OF THE TROPICAL FORESTS OF "RAZIL AND NEIGHBORING COUNTRIES 4HESE DATA ESTABLISHED AN EARLY hGOLD STANDARDv FOR TROPICAL FOREST SURVEYS  SINCE , BAND IS SO MUCH BETTER SUITED TO THIS APPLICATION THAN SHORTER WAVELENGTHS * 
 GPR works well through materials such  as granite, dry sand, snow, ice, and fresh water, but will not penetrate certain clays that  TABLE 21.1  Main Applications of GPR Archaeological investigations Bridge deck analysis Detection of buried mines (anti-personnel and anti-tank) Forensic investigations (detecting buried bodies) Geophysical investigations Pipes and cable detection Rail track and bed inspection Road condition survey Snow, ice, and glacier  ch21.indd   3 12/17/07   2:51:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 
 When this occurs, a high-power modulator,  called a cathode pulser  might have to be used to switch the tube on and off. Cathode  pulsers must switch the full beam voltage and current simultaneously, which involves  high instantaneous powers. They must control the full beam power of the RF tube, either  directly or through a coupling circuit. 
 Now R1and Rz depend onthe bandwidth that isrequired, since the bandwidth ateach crystal isinversely proportional tothe product oftheloading resistance and thetotal capacity, including theelectrostatic capacity ofthecrystal and the stray capacity ofcable connections. This assumes that single- tuned coupling circuits areused. The characteristic impedance R~isinversely proportional tothe active area ofthe crystal and tothe square ofthe frequency. 
 The nulls will also be  filled in if broadband signals are radiated by the radar.  In the above example, the reflection coefficient of the ground was taken to be -1, which  applies for horizontal polarization and a smooth reflecting surface. The magnitude and phase  of the reflection coefficients of vertically polarized energy behave differently from waves with  horizontal polarization (Fig. 
 16 of Knott1 provides an approximation of the  RCS. If the edge is curved, it may be regarded as a collection of infinitesimally short  segments butted together, and the scattered fields may be computed via an integration  of incremental fields diffracted by each element of the edge. This is the concept intro - duced by Mitzner,41 and the summation of the fields diffracted by the edge elements  implies an integral around the edge contour. 
 The output logic formats the / and Q values for transfer to the adaptive processing module. The /, Q pair of numbers is a phasor representing the instan- taneous phase and amplitude of each range cell in rectangular coordinates. Figure 16.25 shows a block diagram of the adaptive processing module used . 
 This is due to the scanning modulation on the difference pattern used for platform-motion compensation. Since the DPCA applies the difference pattern in quadrature to the sum pat- tern to compensate for phase error and step scan applies the difference pattern in phase to compensate for amplitude error, it is possible to combine the two techniques by properly scaling and applying the difference pattern both in phase and in quadrature. The scaling factors are chosen to maximize the im- provement factor under conditions of scanning and platform motion. 
 Since rain attenuation is usually small and unimportant at the  longer wavelengths where this expression is valid, the simplicity offered by the Rayleigh  scattering approximation is or limited use for predicting the attenuation through r.ain.  The computation of rain att,~nuation must therefore be based on the exact formulation for  spheres as developed hy Mic.1 ti The results of such computations are shown in Fig. I .l 13 as a  function of the wavelength and the rainfall rate. 
 TECTURE !DAPTIVE WEIGHTS ARE GENERATED AND APPLIED TO THE  RECEIVE CHANNELS  FORM 
 The Simulation Experiment of Interferometric ArcSAR Extraction DEM Based on the geometric model and working mode of the ArcSAR system, we uses the existing RCS scenes and DEM data to simulate the ArcSAR image on the slant range. To facilitate subsequent experiment, the simulated ArcSAR image is shown in the polar coordinate system in Figure 18. The necessary parameters are given in Table 2. 
 A diffi-  culty was that the magnetron construction employs a  high-tensile casing, almost indestructible and certainly  not likely to be damaged by the self-destruction fuses  fitted to other radar apparatus to destroy it if it fell into  enemy hands. At last this prejudice was overcome, and  centimetre-length radar became general in the air, on  land, and at sea. The magnetron was supplemented by  an equally novel receiving valve evolved by Dr R. 
 ELEMENT ARRAY  AND  BITS IN A  
 ETERS HAVE A SMALL RANGE WINDOW WHOSE POSITION TRACKS THE DELAY AND STRENGTH OF THE  e  4HE 'EOSAT %2- ORBIT WAS CHOSEN FOR POLITICAL AS MUCH AS FOR TECHNICAL REASONS )T FOLLOWED THE 3EASAT ORBIT    THAT HAD ESTABLISHED A WELL 
 By observing the  target with a variable polarization producing independent measurements, the angle error due  to glint is averaged and the effect of the large glint errors is reduced. Experimental measure­ ments with an X-band, conical-scan, pulse doppler radar tracking an M-48 Hink at approxi­ mately 500 m range reduced the angular tracking error by about one-half. In these tests, the  hest results were obtained when the plane of polarization was switched in small increments  (5.6 to 22.5°) at a rate greater than 500 steps per second, which is more than an order of  magnitude greater than the 40 Hz conical-scan rate. 
 QUENCY SHIFT #HAPTER   4HE AIRBORNE DOPPLER NAVIGATOR RADAR IS ALSO BASED ON THE DOPPLER SHIFT 4HE USE OF DOPPLER IN A RADAR GENERALLY PLACES GREATER DEMANDS ON THE STABILITY OF THE RADAR TRANSMITTER  AND IT INCREASES THE COMPLEXITY OF THE SIGNAL PROCESS 
 Preston, G. W.: The Search Efficiency or the Probability Ratio Sequential Search Radar, /RE Intern.  Conv. 
 S. Watts, K. D. 
 However, a420-~sec line giving acceptable perform- ance hasbeen made ofanannealed fused quartz block 6by17by1Scm. This lineoperated at15Me/see with apulse length oflessthan 1psec. .kn internal reflection pattern was employed which resembled thepattern of theliquid delay tank, butusewas made ofthespecific elastic properties of fused quartz toachieve acontrolled transfer ofenergy between compres- sional and transverse modes. 
 L.: On Determining the Presence of Signals in Noise, Proc. I EE, pt. JII, pp. 
 A 3° vertical beamwidth, pointed 0.7°  below the horizon, with cosecant-squared shaping up to 30° will result in the cancellation ratio  being limited to about 13 dB over water and 17 dB over moist soil.86 To minimize the  problem, narrow vertical beamwidths should be employed.  The radar cross section of aircraft targets is, in general, less with circular polarization than  with linear polarization. Experimental measurements87 indicate that when an aircraft is illu­ minated with one sense of circular polarization, the echo power on a statistical hasis is divided  more or less equally between right-hand and left-hand circular polarization. 
 “New wind model,” HWM 93, http://nssdcftp.gsfc.nasa.gov/models/atmospheric/hwm93/hwm93.txt. 58. J. 
 From  the aperture a, a good approximation of half- power bandwidth results:  . Radar System Engineering  Chapter 9 – Synthetic Aperture Radar  77     € ΘH=λ aθHinrad [ ] (10.4)  From here the azimuth resolution is   € Δz−θHR=λ aR (10.5)  If, for example, one would require a range resolution of 1,5 m at a range of 100 km, then the  aperture for 10 GHz would result from:  km cm Rza 2 1015037= =Δ=λ (10.6)  It is not practically possible to realize an antenna of this size.   The fundamental idea for improvement is now a fixed flight route or zone with moving Radar,  which itself is used as an aperture. 
 WHERE IN THE RADAR CONTROL SYSTEM AND IS NORMALLY DEFINED BY TWO DIRECTION COSINES  ! TEST OR MONITORING CIRCUIT SHOULD ESTABLISH THE CORRECT FUNCTIONING OF ALL COMPO 
   %,%#42/.)# #/5.4%2 
 Radar video clutter-maps or computer-generated  information can also be combined on the TV display. A disadvantage of this form of scan  converter is its low resolution. ,  A digital memory can be used as the storage device in a scan converter to overcome  the limitations of the analog storage tube. 
 They pointed out that pulse compression can benefit rapid-scanning radar applications  in which the desired dwell time of each scattering volume is much shorter than the  decorrelation time of the weather echoes. In these cases, averaging pulse compressed  range measurements, instead of integrating over a longer dwell time, provides the  large number of independent samples needed for accurate measurement in a very short  beam observation time. Similarly, the effective range resolution over which averag - ing is performed can be flexible to meet changing observational requirements—short  range intervals for highly structured heavy rainfall storms (typically convective) and  longer range intervals for more uniform but weaker rainfall (typically stratiform). 
 N.: "Radar System Engineering," MIT Radiation Laboratory Series, vol. l, McGraw­ Hill Book Co., New York, 1947.  13. 
 STATE AMPLIFICATION 4HESE INCLUDE THE FOLLOWING.   3/,)$ 
 L-scope, A display in which a target appears as two horizontal blips, one extending to the right from a  central vertical time base and the other to the left; both blips are or equal amplitude when the radar is  pointed directly at the target, any inequality representing relative pointing error, and distance  upward along the baseline representing target distance.  M-scope. A type of A-scope in which the target distance is determined by moving an adjustable pedestal  signal along the baseline until it coincides with the horizontal position of the target signal  deflections; the control which moves the pedestal is calibrated in distance. 
 HAND PICTURE BECAUSE THE CAMERA SHUTTER  WAS OPEN FOR THREE REVOLUTIONS OF THE ANTENNA 4HE 00) RANGE IS  NMI &)'52%   3IMPLIFIED BLOCK DIAGRAM OF A COHERENT -4) SYSTEM  
 V ane, R. J. Boain, G. 
 This circuit will find the correct frequency ifcrossover isanywhere within theelectronic tuning range ofthelocal oscillator. Half asecond isatypical period ofone sawtooth search cycle. The r-fpart ofthe block diagram shows adouble mixer that has separate crystals fortheradar and AFC functions, both receiving power from the radar local oscillator. 
 2016 ,52, 2952–2960. [ CrossRef ] 32. Yang, J.; Zhang, Y. 
 Thisis analogous totheFM-CW radarofChap.3,inwhichthedopplerfrequency shiftisextracted as wellastherange.Itwillberecalledthatthesawtooth frequency-modulated waveform ofthe FM-CW radarwascapableofdetermining therangeas longastherewasnodopplerfrequency shift.Byusingatriangular waveform insteadofthesawtooth waveform itwaspossible to measure boththerangeandthedoppler frequency. Thesametechnique canbeusedwiththe frequency-modulated pulseradar. Classesofambiguity diagrams. 
 Returns from a single point-target fall on a horizontal linq. Since film  records lig C t intensity, the sign of the signal amplitude will be lost if the signal alone is  recorded on the film. To retain the sign of the amplitude, a dc bias equal to or greater than the  most negative signal excursion is added to the signal. 
 ch10.indd   9 12/17/07   2:19:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. The Radar Transmitter. 
 A vacuum tube * with a given average power can usually be  designed to handle the high voltages associated with a large peak power without break - down. A solid-state transmitter cannot. In the past, average powers of radar transmit - ters have been from a small fraction of a watt to the order of a megawatt. 
 63-70,  Decemher, 1967.  2K. Rahiner. 
 BEAM AND SIDELOBE REGIONS. 
 Atmos. Ocean. TechnoL, vol. 
 The  rms accuracies are between 0.05 and 0.1 beamwidth in these regions.'' The choice of  technique to permit tracking of targets at low altitude with reduced error depends on the  degree of complexity that can be tolerated for the amount of improvement obtained.  Electro-optical devices such as TV, IR, or lasers can be used in conjunction with radar to  provide tracking at low target altitude when the radar errors are unacceptable. These deviccs,  however, are of limited range and are not all-weather. 
 3.;\nincreaseillfrcqucncy incrcases boththephaseerrorsandthecorrelation interval in termsofwavelengths. Therefore thegainofaconstant-area antenna doesnotincrease as rapidly asthesquareofthe frequcncy. Forrenectors ofequalgain(samediamcter in wavelengths) Fq.(7.32)showsthattherelativesidelobelevelcausedbyerrorswillincrease ';ISthefourthpowerofthefrequency, or12dB/octave. 
  
 A.: "SIGCLUT: Surface and Volumetric Clutter-to-Noise, Jammer and Target Signal-to-Noise Radar Calculation Software and User's Manual," Artech House, Norwood, Mass., 1987. 31. Ziemer, R. 
 332). The multiplicative noise ratio  (MNR)3 of a SAR image is defined as the ratio of the  image intensity in no-return area  (NRA)  (not including thermal noise) divided by the  average image intensity in a relatively bright surrounding area (in principle not includ - ing thermal noise). An NRA is an area with essentially zero return—for example, a  shadow area, a very smooth area such as a calm lake, or a specially constructed large  sheet of aluminum. 
 Morton, and W. R. Corliss: Worldwide Radio Noise Levels  Expected in the, Frequency Band 10 Kilocycles to 100 Megacycles, Natl. 
 MTI RADAR  2.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 Note that the clutter in Figure 2.17 b is very spotty in character, including the  strong fixed-point targets and returns from extended targets. It is significant that the  extended targets are no longer very extended. The face of a mountain at 10 mi from  5 to 7 o’clock is only a line. 
 The center-frequency delay is limited to less than 75 JJLS for normal lines and 225 IJLS for polygonal lines because of limitations on the size of the quartz. In po- lygonal lines, the acoustic wave reflects off several reflecting faces in traveling from the input to the output array. The wedge-type dispersive delay line14 uses a wedge of quartz crystal and a frequency-selective receiver array to produce a linear delay-versus-frequency characteristic. 
 GROUND ECHO  16.616x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 115. R. K. 
 176-177, 1974. Also Westinghouse Systems Development Division (Baltimore,  Md.) report DSC'-9731 by the same authors titled, Fast Acting Varactors for Sub-Nanosecond Power  Limiting in Receiver Protectors (no date).  54. 
  3AFETY OF .AVIGATION   THE REQUIREMENTS FOR THE CARRIAGE OF NAVIGATION  EQUIPMENT ARE DEFINED 4HESE VARY ACCORDING TO THE SIZE AND PURPOSE OF A SHIP !LL PASSENGER SHIPS AND ALL SHIPS ABOVE  GT NEED TO CARRY AT LEAST ONE RADAR WITH TRACKING FACILITIES &OOTNOTES WITHIN #HAPTER 6 OF 3/,!3 IDENTIFY THE RECOMMENDED )-/ PERFOR 
 PROPAGATION OFSHORT RADIO WAvEs—Kew 14. MICROWAVE ~upLExErm+-Smulzin and Montgomery 15. CRYSTAL RECTIFIERS— Torrey and Whitmer 16. 
 [ CrossRef ] 6. Sheen, D.M.; McMarkin, D.L.; Hall, T.E. Combined illumination cylindrical millimeter-wave imaging technique for concealed weapon detection. 
 The performance of the ML estimation algorithm of target DoA can be studied  by resorting to the Cramer-Rao Lower Bound (CRLB) analysis and Monte Carlo   simulations.104,107–109,113,114 In these studies, it is shown that the shape of the U functional   §  Here, just one jammer is considered; but the mathematical approach is easily extended to more than one jammer. ch24.indd   24 12/19/07   6:00:39 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 .OISE 2ATIO 3.2   &OR A REAL RADAR  FOR WHICH THE EXACT PHASE OF THE  TARGET ECHO CAN NEVER BE KNOWN IN ADVANCE  THE GREATEST ACHIEVABLE SIGNAL 
 £Ç°n  2!$!2 (!.$"//+  TARGET WITH A RANGE RESOLUTION OF  C" ,ET US ALSO ASSUME THAT THE 3!2 IS MOVING IN A  STRAIGHT LINE AT A CONSTANT ALTITUDE  ( AND CONSTANT SPEED  6 FOR A TIME  4 ALONG A DIRECTION  NORMAL TO THE ,/3 4HE SYNTHETIC APERTURE  ,3!   64 IS ASSUMED SMALL COMPARED WITH  THE RANGE  2 TO THE CENTER OF THE TARGET REGION !S VIEWED FROM THE TARGET REGION ALSO  ASSUMED SMALL COMPARED TO  2   THE SYNTHETIC APERTURE SUBTENDS THE SYNTHETIC APERTURE  ANGLE y ,3!2   642 !S THE RADAR MOVES THROUGH ITS SYNTHETIC APERTURE  IT VIEWS THE  SCENE FROM SLIGHTLY DIFFERENT ANGLES &OR SIMPLICITY  LET US ASSUME THAT DURING THIS TIME  THE TARGETS DO NOT LEAVE THEIR hRANGE BINSv OF WIDTH  C" 4HIS ASSUMPTION WILL BE DIS 
 The purpose of the zero-velocity  filter is to recover the clutter signal eliminated by the MTI delay-line canceler and to use this  signal as a means for detecting targets on-crossing trajectories with zero velocities that would  normally be lost in the usual MTI. Only targets larger than the clutter would be so detected. In  each cell of the ground clutter map is stored the average value of the output of the zero­ velocity filter for the past eight scans (32 seconds). 
 .lrmos. Sci., vol. 27,  pp. 
 From space, the ionosphere and/or atmosphere  may corrupt or even prevent radar propagation. The ionosphere may induce Faraday  rotation,§ thus degrading or destroying the polarization properties of the transmit - ted and received signals.4 The Faraday rotation b of a linearly-polarized E-vector is  proportional to RM l2, where the rotation measure RM is a function of ionospheric  electron density. The ionosphere also introduces dispersion and, under certain unfa - vorable circumstances, effectively cuts off propagation. 
 Consider an absorbing atmosphere at an ambient temperature T, surrounded by an  imaginary blackbody at the same temperature. The loss L is the factor by which energy is  PROPAGATION OFRADAR WAVES461 oxygcnmolcculc hasresonanccs at60GlI!.(0.5cmwavelength) and118GHZ.46Atfrequen­ ciesbelowahoutIGHz(Lband)theeffectofatmospheric attenuation isnegligible. Above 10Gllz.itbecomes increasingly important. 
 FORWARD JAMMER IS USUALLY WITHIN THE  LETHAL RANGE OF DEFEN 
 POWER BEAMWIDTH .   -4) 2!$!2  Ó°Óx 4HESE LIMITATIONS  PLOTTED IN &IGURE  AND &IGURE   APPLY TO ALL CANCELERS  WHETHER  SINGLE OR MULTIPLE 4HE DERIVATION OF THESE LIMITATIONS AND A MEANS OF AVOIDING THEM BY THE USE OF TIME 
 NEERS THAT COMPONENTS OF THE RADAR RECEIVER CAN CAUSE DEGRADATION OF THE RADIATED TRANSMITTER SPECTRUM  GENERATING HARMONICS OF THE CARRIER FREQUENCY OR SPURIOUS DOP 
 NOISE RATIO VS ANALOG FREQUENCY FOR VARYING SAMPLE JITTER       
 612] HEIGHT-FINDING J~ITH AFREE-SPACE BEAM ..—.—.—195 –=-l mc.-G. 9*. 196 THEGATHERING ANDPRESENTATION OFRADAR DATA [SEC. 
 Adoarztaqes ofanR-fPackage.—On allbut the largest radar sets the group ofcomponents listed intheprevious paragraph can becompactly mounted inasingle container that isnot too heavy forone man, orat most two men, tocarry. There isconsiderable advantage inhaving the vital parts ofthe transmitter and receiver centralized inaremountable unit package. Intheevent oftrouble, aspare r-fhead canbesubstituted and connected into therest oftheradar inafew minutes. 
 (See Fig. 142.) Atypical example ofalarge 3-phase direct-drive alternator isthe General Electric Company 10-kva 3-phase 208/ 120-volt 400- to800-cycle machine shown inFig. 14.3. 
 LaGrone: Radar Reflections from Insects in the Lower  Atmosphere, IEEE Trans., vol. AP-14, pp. 224-227, March, 1966. 
 These are  t~navoidable with observations of finite duration in the presence of noise. One kind of error 15  to mistake noise for signal when only noise is present. This occurs whenever the noise is large  enough to exceed the threshold level. 
 LAW DETECTOR  !X 4II IN   £q   . 
 ING THE IMPULSE RESPONSE TO BE SHORT IS THAT IT IS IMPORTANT THAT THE ANTENNA DOES NOT DISTORT THE INPUT FUNCTION AND GENERATE TIME SIDELOBES 4HESE TIME SIDELOBES WOULD OBSCURE TARGETS THAT ARE CLOSE IN RANGE TO THE TARGET OF INTEREST IN OTHER WORDS  THE RESOLUTION OF THE RADAR CAN BECOME DEGRADED IF THE IMPULSE RESPONSE OF THE ANTENNA IS SIGNIFICANTLY EXTENDED (OWEVER  IN PRINCIPLE  ALL ANTENNAS ARE DISPERSIVE TO SOME EXTENT BUT NONDISPERSIVE  ANTENNAS DO NOT NEED CORRECTION IN THE SIGNAL PROCESSING  WHICH REDUCES THE OVERALL COMPLEXITY OF THE RADAR PROCESSING 4HE VERY SHORT RANGE OPERATION OF MANY '02 SYSTEMS ENABLES OPERATION OF ANTENNAS IN A WAY THAT DOES NOT CONFORM TO TRADITIONAL ANALYTIC MODELS OF ANTENNA GAIN AND APERTURE (ORN ANTENNAS HAVE FOUND MOST USE WITH &-#7 ULTRAWIDEBAND RADARS WHERE THE  GENERALLY HIGHER FREQUENCY OF OPERATION AND RELAXATION OF THE REQUIREMENT FOR LINEAR PHASE RESPONSE PERMIT THE CONSIDERATION OF THIS CLASS OF ANTENNA &-#7 ULTRAWIDE 
 Also, as we saw in the  preceding chapter, the mere reception of the echo by  itself is not sufficient: that would tell us there was,  indeed, a reflection from some object, but would be no  help at all towards locating its true position. We must,  on our CRT Echt-line, have as markers the blip of the  transmitter (or the equivalent of it, if we desire to black-  out the vis#@l display of this pulse) and the blip of the  echo, so that we may be able to see the difference in time,  and thus in miles, between them. Therefore we want  to arrange the transmitter to ‘trigger off’ the receiver at  each instant when a pulse goes out into space, and the  45  . 
 Compared with the ideal imaging result in Figure 11a, the resolution in azimuth degenerates from 0.713 m to 4.894 m and 7.625 m in the case of CkL=1033and CkL=1034, respectively. The more signiﬁcant deteriorations are shown as the degeneration of PSLR and ISLR. According to Figure 11b, both the PSLR and ISLR decay to −3.19 dB and −3.26 dB and in Figure 11c the PSLR and ISLR drop to −1.45 dB and −0.17 dB, respectively. 
 Katzin, M.: On the Mechanisms of Radar Sea Clutter, Proc. IRE, vol. 45, pp. 
 XXVIIIth URSI General Assembly , New Delhi,  October 2005. 38. R. 
 AMPLIFIERS  THE GYRO 
   2!$!2 #2/33 3%#4)/.   £{°Ó£ CURVATURE AT THE SPECULAR POINT BECOME INFINITE  YIELDING INFINITE 2#3  WHICH IS OBVI 
 W.: Moving Target Indication Radar. IEEE NEREAf 74 Rccord, pt 4: Rudur SJ~S~~,IIIS  and Conrponrnts, Oct. 28-31, 1974, pp. 
 CALLY COMPRISED OF CAPACITORS AND INDUCTORS /PERATOR CONTROL OF THE PULSE LENGTH EFFEC 
 With intermediate voltages, yellow and orange can be obtained,  giving a total of four dinerent colors which can be distinguished. This method of color  excitation permits better resolution to be obtained than with conventional TV color tubes.  The range ofcolors available is not as great as with a color TV tube, but in many information-  display applications it is sufficient. 
 =  3AN &RANCISCO  )%%%523)     PP n  2 ' 3TRAUCH  h! MODULATION WAVEFORM FOR SHORT 
 Ocean. Technol ., vol. 17,  pp. 
 THETIC APERTURE THAN THE CANONICAL CASE 4HIS LOGIC LEADS TO THE hBURST MODE v WHICH FIGURES PROMINENTLY IN TWO FORMS IN SPACE 
 Taylor and L. C. Young of the Naval Research Laboratory  detected a wooden ship using a CW wave-interference radar with separated receiver and  transmitter. 
 a one-of-a-kind developmental height-finder radar built for the Federal  A \'iation Agency. Waveguide transmission lines were arranged to serve as the delay lines.  Energy was tapped from each waveguide at the appropriate points by directional couplers to  form beams at various elevation angles. 
 Milne, K.: The Combination of Pulse Compression with Frequency Scanning for Three-dimensional  Radars. The Radio and Electronic Etlgr.. vol. 
 Guard Channel.  The guard channel mechanization compares the outputs of  two parallel receiving channels, one connected to the main antenna and the sec - ond to a guard antenna (the Σ and Guard channel in Figure 4.8, respectively), to  determine whether a received signal is in the main beam or the sidelobes.40–44 The  guard channel uses a broad-beam antenna that (ideally) has a pattern above the  main-antenna sidelobes. The returns from both channels are compared for each  range-doppler cell that had a detection in the main channel. 
 148. S. J. 
 . 
 The system would behandicapped bythe limitation onangular resolution imposed bywavelength and antenna aperture, but itshould besaid that the possibilities ofstorage inherent inthe mosaic method might eventually offset tosome degree theother apparent disadvantage ofthesystem—its low sensitivity y. Asusual inc-w radar, knowledge oftarget range would not beafforded bysuch asystem without further elaboration. Ifrange istaken into account, the rate atwhich the radar collects information can becomputed inavery direct way. 
 \\\\ \\\\ 2E )M %%(6    WHERE   DENOTES COMPLEX CONJUGATE  AND THE CARATS      INDICATE AN AVERAGE TAKEN OVER  SEVERAL SAMPLES #LEARLY  THE RELATIVE PHASE BETWEEN THE TWO POLARIZATIONS IS AN ESSENTIAL  FACTOR FOR TWO OF THE FOUR 3TOKES PARAMETERS $ATA EXPRESSED THROUGH THE 3TOKES PARAM 
 TION AND TRACKING OF AIR AND SHIP TARGETS "Y USING THE IONOSPHERE AS A PROPAGATION MEDIUM   SKYWAVE /4( RADARS CAN OPERATE AT VERY LONG DISTANCES TO ACHIEVE DETEC TION  AND TRACKING AT RANGES OF n KM /N THE OTHER HAND   SURFACE 
 n /THER CLIMATOLOGICAL MODELS USED  IN (& RADAR APPLICATIONS ARE 0)-   02)3-   AND &!)- u 0HYSICS 
 and N0 = N/B is the noise power per unit bandwidth, or the noise energy. Also  note that Br ~ 1, and T0 Fn = ~ is defined as the system noise temperature. Then the radar  equation becomes  R4 = Er GAp 0<rnE;(11)  max (4rr)2kJ;(E/No)1 Ls (2.55)  Although Eq. 
 CLONES AT RANGES IN EXCESS OF  KM )T SHOULD BE CLEAR THAT ANY MEAN TRANSLATIONAL  MOTION WOULD CHANGE THE ABSOLUTE  VALUES OF THE MEASURED RADIAL  VELOCITIES BUT WOULD  NOT AFFECT THE SHEAR MEASUREMENT !ZIMUTHAL SHEAR VALUES OF THE ORDER OF n Sn  OR GREATER AND WITH VERTICAL EXTENT GREATER THAN THE DIAMETER OF THE MESOCYCLONE ARE DEEMED NECESSARY FOR A TORNADO TO OCCUR  $ETECTION OF THE TORNADO VORTEX ITSELF IS NOT GENERALLY POSSIBLE BEYOND ABOUT  KM  USING TYPICAL WEATHER RADAR BEAMWIDTHS  SINCE ITS HORIZONTAL EXTENT MAY BE ONLY A FEW HUNDRED METERS $ETECTION OF THE RADIAL SHEAR  THEREFORE  IS NOT POSSIBLE UNLESS THE TOR 
 ON 
 Practitioners in the field of radar meteorology often use Ze and Z  interchangeably, albeit incorrectly. Another factor we have ignored in the derivation of the radar equation is attenua - tion by precipitation and atmospheric gasses. At 10 cm wavelengths the attenuation is  usually not significant; however, at 5, 3, and 2 cm and especially the yet shorter mm  wavelengths, atmospheric attenuation must be accounted for in the radar equation by  adding an additional range dependent term La. 
 TIVE OF NATURAL  EQUIPMENT 
 February, 1958. 67.Hiatt,R.E..K.M.Siegel,andH.Weil:Forward Scattering byCoatedOhjects Illuminated hyShorl Wavelength Radar,Proc.IRE.vol.48.pp.1630-1635, Septemher. 1960. 
 Ê*," 
 These models yield variations from a° independent of angle through a° « cos 6 to cr° <* cos2 6. Since the sphere models are highly artificial, only the resulting scatter laws need be considered. Most targets give returns that vary more rap- idly over part of the incidence-angle regime than these models, although for- ests and similar rough targets of some depth sometimes give such slowly vary- ing returns. 
 SPHERIC BOUNDARY LAYER  hCLEAR AIRv  : VALUES OF THE ORDER n D" : TO  D" : ARE TYPICAL  AND FREQUENTLY ORIGINATE FROM INSECTS AND BIRDS  )N RAIN : MAY RANGE FROM ABOUT   n D": TO AS MUCH AS  D" :  WITH A  TO  D" : RAIN BEING OF THE TYPE THAT  CAN  CAUSE SEVERE FLOODING 3EVERE HAILSTORMS MAY PRODUCE  : VALUES HIGHER THAN  D" :  -ANY OPERATIONAL RADAR TYPES ARE DESIGNED TO DETECT THOSE : VALUES THAT PRODUCE MEA 
 Material from IMO publications is reproduced with the kind permission of the  International Maritime Organization (IMO), which does not accept responsibility  for the correctness of the material as reproduced: in case of doubt, IMO’s authentic  text shall prevail. 2. The author thanks the International Electrotechnical Commission (IEC) for per - mission to reproduce information from its International Standard IEC 62252  ed.1.0 (2004). 
 The aspect entropy for an isotropic target is higher because the scattering is stable in all azimuth angles. We calculate the aspect entropy of the four models mentioned above and the results are listed in Table 1. The results show that aspect entropy can indicate the anisotropy diversity of the four shapes, and therefore can be used as a descriptor of anisotropy. 
 WAY !TTENUATION #OEFFICIENT + IN #LOUDS IN D"KM PER GM ,IQUID 7ATER 4EMPERATURE  n#7AVELENGTH  CM     7ATER CLOUD                n      )CE CLOUD   r n r n r n r n n  r n r n r n r n n  r n r n r n r n   EXTRAPOLATED VALUE. 
 PLANE PATTERN IN THE LEFTMOST CHART AND LIKE A DIAMOND  E   n  IN THE RIGHTMOST CHART 4HE AMOUNT OF SURFACE DISTRIBUTED TOWARD  THE SIDES OF THE PLATES INFLUENCES THE SIDELOBE LEVELS 4HE 0/ INTEGRAL IS SOMEWHAT MORE COMPLICATED TO EVALUATE WHEN THE SURFACE IS  SINGLY OR DOUBLY CURVED !N EXACT  EVALUATION CAN BE PERFORMED F OR A CIRCULAR CYLINDER  AND A SPHERICAL CAP VIEWED ALONG THE AXIS OF SYMMETRY  BUT NOT FOR A TRUNCATED CONE OR A SPHERICAL CAP SEEN ALONG OTHER THAN THE AXIS OF SYMMETRY %VEN SO  THE EXACT EVALU 
 Chan, “An integrated maritime surveillance system based on  high-frequency surface-wave radars, part 2: Operational status and system performance,” IEEE  Antennas and Propagation Magazine , vol. 43, no. 5, pp. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 
  2ECEIVER .OISE ,EVEL D"M(Z 
 MIZING THE ANGLE ERROR CAUSED BY RECEIVER THERMAL NOISE (OWEVER  IF SIDELOBES ARE A PRIME CONSIDERATION  A SOMEWHAT DIFFERENT FEED SIZE MAY BE DESIRED 4HE LIMITATION OF THE FOUR 
 Contributions tothe cross section can beseparated roughly into two parts. The first arises from flat orgently curved surfaces ofconsiderable area (insquare wave- lengths) which arenormal totheline joining thetarget and transmitter. Radiation returned from such surfaces may beproperly classed asspecular reflection; cross sections arising therefrom willbereferred toas“specular cross sections. 
 67. J. J. 
   PP n   *ANUARY   # * 3LETTEN ET AL  h/FFSET DUAL REFLECTOR ANTENNAS FOR V ERY LOW SIDELOBES v  -ICROWAVE *   PP n  -AY   7 6 2USCH  h4HE CURRENT STATE OF THE REFLECTOR ANTENNA ART v  )%%% 4RANS !NTENNAS 0ROPAG   VOL !0 
 QUENCY 3UCH A ROTARY 
 COORDINATE TRACKER  IS DESCRIBED  )F THE TARGET WERE ON THE ANTENNA BORESIGHT AXIS  THE OUTPUTS OF EACH   &)'52%     A  7AVEFRONT PHASE RELATIONSHIPS IN A PHASE COMPARISON MONOPULSE RADAR AND  B  BLOCK  DIAGRAM OF A PHASE COMPARISON MONOPULSE RADAR ONE ANGLE COORDINATE . 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing.  RADAR DIGITAL SIGNAL PROCESSING  25.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 (FIR filters are described in Section 25.4), where the top and bottom filters apply the  real and imaginary parts of the coefficients, respectively. The equivalent complex- impulse-response filter, with the frequency response shown in line 4 of Figure 25.14,  is a halfband filter because that frequency response and a version shifted in frequency  by half a period sum to a constant. 
 Gorokhov, and N. K. Spencer, “Stochastic constraints  method in nonstationary hot clutter cancellation, part I: Fundamentals and supervised training  applications,” IEEE Trans. 
 Castellazzi, P .; Arroyo-Dominguez, N.; Martel, R.; Calderhead, A.I.; Normand, J.C.L.; Garﬁas, J.; Rivera, A. Land subsidence in major cities of central Mexico: Interpreting insar-derived land subsidence mapping with hydrogeological data. Int. 
 For the upper end of the solid-state microwave spectrum, i.e., the millimeter- wave range, the single-port microwave diode can be used as a low-power oscillator.  Unfortunately, the power output and efficiency of these devices are, in general, very  low; in fact, the efficiency is significantly lower than that of their tube counterparts.  However, CW and pulsed power output are attainable up to 300 GHz. 
 OPTICS 2#3 IS SHOWN BY THE UPPERMOST TRACE  ALL THE OBJECTS HAVE THE SAME NOSE ANGLE    AND OF THE SIX SHAPES  THE OGIVE EXHIBITS THE LOWEST 2#3 4HUS  AT LEAST ALONG THE AXES OF THESE PARTICULAR BODIES  THE 2#3 CAN BE MINIMIZED BY SELECTING THE APPROPRIATE SURFACE PROFILE (OWEVER  THE ATTAINMENT OF LOW ECHOES OVER A RANGE OF ASPECT ANGLES IS USUALLY  ACCOMPANIED BY HIGHER ECHO LEVELS AT OTHER ANGLES 4HUS  THE SELECTION OF AN OPTIMUM SHAPE SHOULD ALWAYS INCLUDE AN EVALUATION OF THE VARIATION OF THE 2#3 OVER A RANGE OF ASPECTS WIDE ENOUGH TO COVER THE ANTICIPATED THREAT DIRECTIONS 4HIS IMPLIES THE CAPA 
 LOOK SYSTEM  A REASONABLE 3CAN3!2 MODE COULD BE   
 Nove~n-  her. 1947. f'  10. 
 87. Rakut. P. 
 (ILL  "OOK #OMPANY    ! ' +URASHOV ED   3HORTWAVE !NTENNAS   %D  IN 2USSIAN  2ADIO I SVYAZ  *ANUARY   3 * !NDERSON  h,IMITS TO THE EXTRACTION OF INFORMATION FROM MULTI 
 12Thismixeriscapableofwidebandwidth, andisrestricted onlybythefrequency sensitivity ofthestructure ofthemicrowave circuit.The noisefigureofanimage-recovery circuit(Fig.9.4)iscompetitive withotherreceiver front­ ends.Theirhage-recovery mixerisattractive asareceiver front-end becauseofitshighdy­ namicrange,lowintermodulation products, lesssusceptibility toburnout, andlesscostas compared tootherfront-ends. 13 Diode mixer RF InputIF output Figure9.3Image-recovery mixer.. 350 INTRODUCTION TO RADAR SYSTEMS  Diode burnout. 
 The shape of the array permits flush mounting and it can be  hardened to resist blast.  Till:FI.!'CIRONICALLY STEI'RFD PHASFD ARRAY ANTENNA INRADAR335 orthogonal coordinate. Thisapproach isgenerally easierthanusingphaseshiftersto scaninbothcoordinates, butaswithanyfrequency-scanned arraytheuseofthe frequency domain forotherpurposes islimited whenfrequency isemployed for heaIll-steeri11g. 
 FED REFLECTOR ARCHITECTURES ARE WELL SUITED FOR SUCH APPLICATIONS AND ARE DESCRIBED IN GREATER DETAIL IN 3ECTION  4HREE RELEVANT EXAM 
 Thedecrease inradarcoverage duetotheattenuation ofelectromagnetic energyinthe diffraction regionisillustrated byFig.12.8foraradaroperating atafrequency of500MHz. Thesecurvesaretheoretical contours ofconstant radarcoverage. Theradarheightisassumed tobe200ftabovethecurvedearth.Curve1represents thelocusofthegeometrical lineofsight asdefinedbyEq.(12.14)fork=lCurv~2istheconstant signalcontour inthediffraction regionforasignalstrength equaltothefree-space signalthatwouldbereceived fromarange ofapproximately 220nautical miles;thatis,iftheradaristodetectatargetthatliesalongthis contour, itmustbecapableofdetecting thesametargetinfreespaceatarangeof220nautical miles.Ifthetargetwereatanaltitudeof200ft,themaximum detection rangewouldbe reduced from220toabout35nautical·miles. 
 EXTRACTION orINH>RMATION ANDWAVEFORM DESIGN403 Theechosignaly(t}iscomposed ofsignalandnoise,s(t-To)+n(t),wheres(t-To)is theechosignalintheabsence ofnoise.Thecontributions duetosignalSoandnoisenoatthe outputofthelow-pass filtermaybeexpressed as (11.6) (11.7) Defining ~TR=TR-To,theformoftheoutput so(~TR)withanoptimum gatingsignal shouldbeanoddfunction. Itsvalueiszeroat~TR=0,anditseven-order derivatives arezero. Forsmallvaluesof~1R,theoutputwillbedirectlyproportional to~TR•(Thusitissimilarto .theangle-error detector ofamonopulse tracking radar.) Theratiooftherootmean-square noisevoltage(;;;)1/2totheslopeMoftheoutput I(~TR)evaluated at~TR=°willbetakenasameasure ofthermserrorintimemeasure­ ment.or (11.8) where(-2)1/2 (5TR=(~t2)1/2 =~_ M M=[~~~~~)LTR=O Theerrorisillustrated inFig.1l.3.Thereceiveroutputcharacteristic withsignal Soonlyis represented bythesolidcurve.TheelTectofnoiseisshownbythedashedcurve.Noise displaces thezerocrossing byanamountM. 
 3,  pp. 80-84, March, 1960.  53. 
 PPM focusing is not suited to large average-power tubes. At  X band, the maximum average power is probably under a kilowatt.8 In some klystrons the  electron beam may be confined by electrostatic fields designed into the tube structure so that  external magnets are not required.40  In a high-power klystron, from 2 to 5 percent of the beam power might normally be  intercepted by the interaction structure, or body of the tube. If the beam were not properly  confined in a high-power klystron, the stray electrons that impinge upon the metal strucll:re of  the tube would cause it to overheat and possibly be destroyed. 
 IEE, vol. 133, pt. F, pp. 
 Jr.: Digital Generation of Wideband LFM Waveforms, IEEE 1975  lnternational Radar CoMerence, pp. 170- 175, Apr. 2 1-23, 1975, IEEE Publication 75 CHO 938- 1  AES. 
 And many of these new technologies are being deployed in countries throughout the world. In the research arenas, multiple-doppler radars are used for deriving three- dimensional wind fields.3 Airborne doppler radar4'5 has been used to duplicate these capabilities, thus providing for great mobility. Polarization diversity techniques6 are used for discriminating ice particles from water, for improved quantitative precipitation measurement, and for detecting hail. 
 Raw SAR data rate is proportional to the image quality factor, swath width, space - craft velocity, and the number of digital bits per data sample. Of course, mean data  rate can be relaxed if the data from any given pass can be collected and then played  back at a slower rate. Although this strategy was exploited by the Magellan  design,  tolerance for which was set up by the elliptical orbit, it was not sufficient to solve the  limited data-rate problem. 
 {°În  2!$!2 (!.$"//+  -273 CAN ALSO BE IMPLEMENTED WITH A HIGH 
 Dyer and N. C. Currie, “Some comments on the characterization of radar sea echo,” in   Dig. 
 The impedance variation relative to a matched impedance at broadside may be obtained imme- diately from zm/t(e,c|>) = i + rm,(e,(|>) zmn(o,o) i - rmw(e,<t>) Analytical Techniques. Stark60 presents a thorough description of analytical techniques and insight to the problem of mutual coupling. He derives necessary and sufficient conditions for array blindness (i.e., nulls in the active element pattern). 
 The filse alarms with non-Rayleigh clutter can be  reduced to any desired level by raising the receiver threshold. Raising the threshold, however,  can require a significantly larger signal-to-noise, or signal-to-clutter, ratio for a given proba-  bility of detection.  Trunk and GeorgeI2 were among the first to note that something other than the conven-  tional receiver design should be used when tlie clutter pdf is not Rayleigl~. 
 The uniform probability-density (Fig. 2.2a) is defined as  p(x) Jk  \O for a< x <a+ b  for x < a and x > a + b  t In noise theory it is customary to take the resistance as 1 ohm or the conductance as 1 mho.  I f"' b ---~ -~-----,  b  _____ __,__.J......... 
 APERTURE PRODUCT  .OTE THAT THE RADAR FREQUENCY DOES NOT APPEAR  EXPLICITLY  IN THE SURVEILLANCE RADAR EQUATION 4HE CHOICE OF FREQUENCY  HOWEVER  WILL ENTER IMPLICITLY IN OTHER WAYS *UST AS THE RADAR EQUATION FOR A SURVEILLANCE RADAR IS DIFFERENT FROM THE CONVENTIONAL  RADAR EQUATION OF %Q  OR THE SIMPLE RADAR EQUATION OF %Q    EACH PARTICULAR APPLICA 
 Note again the advantage  of showing M-unit gradients versus N-unit gradients. From Figure 26.7, it can be seen  that the duct extends from the top of the trapping layer downward until it intersects  with the M-unit line where the M-unit at the top of the duct is the same as the M-unit  at the bottom of the duct (illustrated by the dashed line). Great semipermanent surface high-pressure systems, centered at approximately 30°  north and south latitude, cover the ocean areas of the world. 
 It parallels  Taylor's approach to the sum pattern.  7.7 COSECANT-SQUARED ANTENNA PATfERN  It was shown in Sec. 2.11 that a search radar with an antenna pattern proportional to csc20,  where 8 is the elevation angle, produces a constant echo-signal power for a target !lying at  constant altitude, if certain assumptions are satisfied. 
 EARTH 
 K. Bhattacharya et al., “Cross-polarized radar processing,” Report TP 13263E, Transportation  Development Centre, Transport Canada, 1998. 19. 
 The elevation analogue of themicro-B (Sec. 6.5) hasfound no application, since the distortion of the E-scope isnot particularly harmful and, byallowing ittooccur, thedispersion intheelevation coor- dinate can benormalized tomake themost e%ective useofthetube face. Insome older sets, the E-scope isused forheight indication, but itsdis- tortion and itspoor height dispersion atlarge ranges make itinferior to theRHI forthis purpose. 
 The  cosecatlt-sqi~ared sllapitig of the atltctirla also utilizes tlie inverse fourth power variation witli  range (Sec. 2.1 1). Tllus, when STC is used witli a cosecant-squared antenna pattern, the  high-angle coverage of the radar is reduced. 
 STATE AMPLIFIER  SUCH AS THE TRANSISTOR  HAS ALSO BEEN USED IN RADAR  ESPE 
 4.Cards bearing the information listed under (4)ofthe preceding paragraph areput into amarker called a“Christmas tree. ” 5.The Christmas tree ismoved onto alarge plotting board tooccupy theposition reported forthetrack. Allofthe steps just described require time, and the large plotting board atthe FCC isusually between three and five minutes behind the existing airsituation. 
 ,/" -Ê**   
 TION AMPLITUDE  AND CROSSRANGE DISPLACEMENT IS PROPORTIONAL TO THE VIBRATION FREQUENCY  SEE 3ECTION  OF 3ULLIVAN  &OR BRIGHT  POINT 
 3The hard-tube pulser hasan internal impedance equal tothat ofthe output tube, which varies from 90to150 ohms until saturation isreached. The line-type pulser, being essentially aconstant-voltage device inseries with animpedance equal tothe load resistance, has aresistance of400 to1200 ohms. Conse- quently, the conditions ofstable operation foragiven magnetron w-ill vary with load and pulser type. 
 53. Albersheim, W. J.: Elevation Tracking Through Clutter Fences, Stipplrrnrtir ro IEEE Tru~ls., vol. 
 The other is the  i11tensity-modulated CRT, such as the PPI, in which a target is indicated by intensifying  the electron beam and presenting a luminous spot on the face of the CRT. In general,  deflection-modulated displays have the advantage of simpler circuits than those of intensity­ modulated displays, and targets may be more readily discerned in the presence of noise or  interference. On the other hand, intensity-modulated displays have the ·advantage of present­ ing data in a convenient and easily interpreted form. 
 A suitable generator, type UO, could not be made available for production before Ma rch 1945. There was consideration given to delaying the whole ASV Mk. VIA and VIB programmes, on which themodulator was also used, until that date. 
 TIIE RADAR EQUATION 23  engineer. It describes tile envelope of tile noise output from a narrow hand filter (such as the l F  filter in a supcrheterodyne receiver). the cross-section fluctuations of certain types of complex  radar targets. 
  AIRFRAME APPARENTLY RECOGNIZED EARLY IN THE DESIGN  WORK THAT IT WOULD BE NEARLY IMPOSSIBLE TO REDUCE THE LEADING EDGE 2#3 OF THEIR SUB 
 I:.: A 1)u;tI Mode 1)igital P~.occssnr for Medium Resolution Synthetic Apcrtirrc  Radars. Itrr~~r.irtrriorr~rI ('or~/c,r.c,trc~c~ R:ll):lK-77. pp. 
    PP n  .OVEMBER    2 7 ,ARSEN  ! -AFFETT  & 3MITH  2# (EIMILLER  AND ! &ROMM  h-EASUREMENTS OF BISTATIC  CLUTTER CROSS SECTION v %NVIRONMENTAL 2ESEARCH )NSTITUTE OF -ICHIGAN  &INAL 4ECHNICAL 2EPORT 2!$# 
 [ CrossRef ] 17. Ng, A.H.M.; Ge, L.L.; Li, X.J.; Zhang, K. Monitoring ground deformation in Beijing, China with persistent scatterer sar interferometry. 
 (Further information regarding radar measurements can be found in Ref. 7.)  Theoretical radar accuracies may be derived by a variety of methods including those  based on (I) simple geometrical relationships between signal, noise, and the parameter to be  measured, (2) inverse probability, (3) a suitably selected gating function preceded by a  matched filler, and ( 4) the estimate of the variance using the likelihood function. The measure  of the error is the root mean square of the difTerence between the measured value and the true  value. 
 Continuous rotation is  general, but with some search systems, where a full  360-degree cover is not essential, the aerial and the PPI  coils may be swung over a small arc.  . PICTURE ON THE TUBE II  Many PPI tubes are for direct reading on the tube end,  but the Skiatron-type projection can be used to display  the map picture on a large screen. 
 .InBrit.ainthedevelopment ofradarbeganlaterthanintheUnitedStates.S-11But becausetheyfeltthenearness ofwarmoreacutelyandwereinamorevulnerable position with respecttoairattack,theBritishexpended alargeamountofeffortonradardevelopment. By thetimetheUnitedStatesenteredthewar,theBritishwerewellexperienced inthemilitary applications ofradar.Britishinterestinradarbeganinearly1935,whenSirRobertWatson­ Wattwasaskedaboutthepossibility ofproducing adeathrayusingradiowaves.Watson­ Wattconcluded thatthistypeofdeathrayrequired fantastically largeamounts ofpowerand couldheregarded asnotbeingpractical atthattime.Instead,herecommended thatitwould bemorepromising toinvestigate meansforradiodetection asopposed toradiodestruction. (Theonlyavailable meansforlocating aircraftpriortoWorldWarnweresoundlocators whosemaximum detection rangeunderfavorable conditions wasabout20miles.)Watson­ Wattwasallowed toexplorethepossibilities ofradiodetection, andinFebruary, 1935,he issuedtwomemoranda outlining theconditions necessary foraneffectiveradarsystem.Inthat samemonththedetection ofanaircraftwascarriedout,using6-MHzcommunication equip­ ment,byobserving thebeatsbetween theechosignalandthedirectlyreceived signal(wave interference). 
 -   % & +NOTT  h2ADAR OBSERVABLES v IN  4ACTICAL -ISSILE !ERODYNAMICS 'ENERAL 4OPICS  6OL    - * (EMSCH  ED  7ASHINGTON  $# !MERICAN )NSTITUTE OF !ERONAUTICS AND !STRONAUTICS     #HAP    % ' 3CHNEIDER  h2ADAR v  0ROC )2%  VOL   PP n  !UGUST    3 $ 2OBERTSON  h4ARGETS FOR MICROWAVE NAVIGATION v  "ELL 3YST 4ECH *  VOL   PP n     * ! 3TRATTON   %LECTROMAGNETIC  4HEORY  .EW 9ORK -C'RAW 
 6.12] HEIGHT-FINDING WITH AFREE-SPACE BEAM 187 The angular range through which this height-finding scheme isuseful isshown inFig. 6.21 bydotted lines. Atlow angles thevariation ofratio with angle isfartoo slow. 
 They produce at  the input of a victim system a background that impedes the detection and recognition of  useful signals and determination of their parameters. The most common forms of active  noise jamming are spot, swept, and barrage noises. Spot noise is used when the center  frequency and bandwidth of the victim system to be jammed are known and confined to  a narrow band. 
 There is only a time delay relationship between images of different view angle. Therefore, image fusion does not require additional registration. Multi-angle images can be quickly and accurately fused. 
 These include electronic countermeasures and other aspects of elec - tronic warfare, antiradiation missiles to home on radar signals, and low cross-section  aircraft and ships. Radar is also used by the military for reconnaissance, targeting  over land or sea, as well as surveillance over the sea. On the battlefield, radar is asked to perform the functions of air surveillance (includ - ing surveillance of aircraft, helicopters, missiles, and unmanned airborne vehicles),  control of weapons to an air intercept, hostile weapons location (mortars, artillery, and  rockets), detection of intruding personnel, and control of air traf fic. 
 The phase shift associated with the return  signal is (4~/R 0/c)/(1 -v/c), where R0 is the range at time t = 0.  Applications of CW radar.24·25 The chief use of the simple, unmodulated CW radar is for the  measurement of the relative velocity of a moving target, as in the police speed monitor or in  the previously mentioned rate-of-climb meter for vertical-take-off aircraft. In support of auto­ mobile traffic, CW radar has been suggested for the control of traffic lights, regulation of toll  booths, vehicle counting, as a replacement for the" fifth-wheel" speedometer in vehicle testing,  as a sensor in antilock braking systems, and for collision avoidance. 
 However, the use of AGC degrades the system’s sensitivity, so large FIGURE 4.14  Postdetection STC levelsUnambiguous Range (log scale)Amplitude (dB) CFAR ThresholdSTC Onset RangeTarget in Main Bea mSTC Threshol dSidelobe Discrete ch04.indd   24 12/21/07   2:37:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 Collin and 1;. J. Zucker  (eds.), McGraw-t1ill Book Co., New York, 1969, p. 
 DELAY CANCELERS  GIVE ANSWERS THAT ARE  FAIRLY CLOSE TO THE ACTUAL LIMITATION THAT WILL BE EXPERIENCED FOR MOST PRACTICAL STAGGER  RATIOS !N EXAMPLE OF THE ACCURACY IS AS FOLLOWS ! SYSTEM WITH   HITS PER BEAM 
 Paraboloidal reflectors (in the receive mode) convert incoming plane waves into spherical phase fronts centered at the focus. For this reason, feeds must be point-source radiators; i.e., they must radiate spherical phase fronts (in the trans- mit mode) if the desired directive antenna pattern is to be achieved. Other char- acteristics that a feed must provide include the proper illumination of the reflec- tor with a prescribed amplitude distribution and minimum spillover and correct polarization with minimum cross polarization; the feed must also be capable of handling the required peak and average power levels without breakdown under all operational environments. 
 £   P    WHERE &M IS THE 4AYLOR COEFFICIENT AND  N IS THE NUMBER OF TERMS IN THE WEIGHTING FUNC 
 The Nexrad radar system, with  its high quality antenna and 50 dB of clutter rejection, is well suited to this important  operational task. Refractivity and Water Vapor Measurements.  Conventional weather radar pro - cessing is generally designed to emphasize precipitation and wind-field measurements FIGURE   19. 
   PP n    $ 6AILLANT AND ! 7ADSWORTH  h0RELIMINARY RESULTS OF SOME REMOTE SENSING CAMPAIGNS OF THE  &RENCH !IRBORNE 3!2 6!2!. 
 7 .22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 Many modern radars use coherent processing to remove clutter. For the purpose of  applying the previous discussions on noncoherent processing to coherent processing,  the integrated output in a range-doppler cell of the doppler processor for a single coher - ent processing interval (CPI) can be treated as a single noncoherent pulse. Because  three ambiguous measurements (i.e., detections) are usually required to remove the  range and doppler ambiguities,36,37 4 to 8 CPIs may be transmitted, and hence, there  are usually 4 to 8 noncoherent pulses available for processing. 
 A transmitter-to-receiver LOS is not  required unless periodic clock synchronization is implemented over the direct path. The traditional method for converting target range sum into target range from the  receiver, RR, is13  RR R L R R LRT R T R R=+ − + +( ) ( s in )2 2 2 q (23.13) The baseline L can be determined using GPS or other methods such as an emitter loca - tor for noncooperative transmitters. As outlined in Section 23.2, the receiver look angle,  qR, can be measured directly with a phased array antenna that scans in two dimensions,  ch23.indd   17 12/20/07   2:21:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Although ofvalue forthis purpose, this type ofscreen has several dis- advantages. Contrast isalways low, particularly iftheduty ratio ofthe pulses islow. Furthermore, such ascreen has the unhappy property that signals tend to“burn in” with time, which isadefinite handicap inachanging picture and isdisastrous inthepresence ofcertain forms of interference. 
 For unstable atmospheric conditions (conditions where a cooler layer of air overlies  a warmer layer of air), stronger winds generally result in stronger signal strengths  (or less propagation loss) than do weaker winds.Trapping layer Surface-based duct Modified refractivityHeight FIGURE 26.5  Surface-based duct ch26.indd   11 12/15/07   4:53:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation. 
 33-35.  159. Ruvin, A. 
 IEEE  Trans., vol. AES-I I. pp. 
   BUTTERFLY     &)'52%   %IGHT 
 Air Force, the transmit array con-  tains 5 184 identical modules using the Eimac 4CPX250K ceramic tetr~de.~~ Each module has  a peak power of 10 k W and is 7 by 9 by 3 1 inches with a weight ofnearly 50 Ib. The array operates  with a 10 Mllz haridwidth centered at 442 MHz.  RADAR TRANSMln'ERS 213 requires 50kWofdrivepoweramioperates with30kVanodevoltageand70Aofpeakanode currcnt. 
 SENTS ANY RADAR SYSTEM LOSSES )ONOSPHERIC LOSSES  WHILE PREDICTED ON A STATISTICAL  BASIS  CAN CONSTITUTE A MAJOR UNKNOWN IN REAL 
 37, pp. 608-615, April, 1965.  29. 
 Repr. 186, Feb. 19, 1951. 
 Shortening the pulse width improves the range  accuracy, but at the expense of the doppler-velocity accuracy. Although the shape of the ellipse  can be as thin or as broad as one likes in either axis, the opposite will be true for the other axis.  The region in the vicinity of the origin cannot be made as small as we wish along both axes  simultaneously without shifting some of the completely shaded region elsewhere in the  diagram. 
 1970. 36.Holt.F.S..H.M.Johanson. C.F.Winter. 
 The parabolic torus is gen­ erated by rotating a section of a parabolic arc about an axis parallel to the latus rectum of the  parabola. The cross section in one plane (the vertical plane in Fig. 7.16) is parabolic, while the  cross section in the orthogonal plane is circular. 
 In  this case, they can be used in conjunction with an image rejection filter, reducing the  magnitude of rejection required by the filter. FIGURE 6.3  Image reject mixerIn-phase  power  dividerRF  SIGNALLOCAL  OSCILLA TOR−90º −180º −180ºHIGH  SIDEBAND LOW  SIDEBAND+90º− ch06.indd   13 12/17/07   2:03:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Gain control is described in more detail in Section 6.6. Effect of Characteristics on Performance.  Noncoherent pulse radar perfor - mance is affected by front-end characteristics in three ways. 
 It is com - mon for phase shifters and attenuators to each have as many as 7 bits or 128 different  states. In addition, active components should be characterized at several frequencies in  the operating frequency band and over several temperatures. As a result, thousands of  measurements are required to fully characterize the performance of each element. 
 Thesubreflector is transparent tovertically polarized. waves.anddoesnotblocktheaperture. Someaperture blocking bythefeeddoesoccur,butthis'canbemadesmall.Inoneairborne monopulse radar antenna23usingthepolarization twistingtechnique, goodperformance wasobtained overa12 percentbandwidth. 
 ElectrO/lies (Dayton, Ohio),pp.683-687, 1959. 52.Kramer. E.:AHistorical SurveyoftheApplication oftheDoppler Principle forRadioNavigation, IEEETrans..vol.AES-8.pp.258-263. 
 6.13 This type ofheight finder isfree from the range limitation which arises from thescanning loss ofarapidly scanning system. The V-beam can, inprinciple, find height toany range where asearch setofthecame antenna size can detect aircraft. Heights onsingle aircraft out to140 miles have been recorded. 
 Inpractice, theobserved maximum radarrangesareusuallymuchsmallerthanwhatwouldbe predicted bytheaboveequations, sometimes byasmuchasafactoroftwo.Therearemany reasonsforthe'failureofthesimpleradarequation tocorrelate withactualperformance, as discussed inChap.2.. .......·.. THE NATURE OF RADAR 5  1.3 RADAR BLOCK DIAGRAM AND OPERATION  Ttle operation of a typical pulse radar may be described with the aid of the block diagram  shown in Fig. 
 Mk. VI Discrimination, Air/Sea Warfare Development Unit (A.S.W.D.U.) Report No. 45/20, 22nd June 1945 (TNA AIR 65/182) [19] Performance of ASV Mk. 
 13.34. The B-scopes used areofthemagnetic type described inSec. 13.14 and illustrated inFig. 
 ABLE ATTENUATOR AND A VARIABLE PHASE SHIFTER AND COMBINED WITH THE RECEIVED SIGNAL 4HE AMPLITUDE AND PHASE OF THE SIGNAL SAMPLE ARE THEN ADJUSTED SO AS TO CANCEL THE SIGNAL RECEIVED IN THE ABSENCE OF THE TARGET 4HE AVAILABILITY OF LOW 
 LINE AND HYBRID 
 In some cases, both a mesocyclone and its incipient  tornado can be detected. Wilson and Roesli138 show an excellent early example of a  tornado vortex signature (TVS) embedded within a larger mesocyclone. Microbursts. 
 In Section 3, we introduce the novel KA-DBS algorithm in detail. The performance of the proposed algorithm is veriﬁed by real measured data in Section 4. Finally, some conclusions are given in Section 5. 
 Figure 3.4 shows this range-dependent filter characteristic, which may be ex- pressed mathematically as . dB = 10 log 4 sin2 (2vfmR/c) = 10 log 4 sin2 (ir/mf) (3.4) where fm = modulation frequency, Hz R = range, m c = propagation velocity, 3 x 108 m/s t = time delay = 2RIc A short time delay can tolerate much higher disturbance at low modulation frequencies, as illustrated by the two cases in Fig. 3.4. 
 Radar System Engineering  Chapter 9 – Synthetic Aperture Radar  82     10.5 Maximum Resolution Capability   For consideration of the resolution capability D, it must be ensured that the Radar contin u- ously illuminates the target, while it moves in the z direction for the length of the synthetic  aperture  € L.  From this the result according to Equation (9.5) is:   00 00 0 sin sin sin θθθλ θR R azLH= ⋅=Δ=  (10.21)  The requirement of the half- power bandwidth of the antenna θH is:  00 sin RL aHθθλ≥ =  (10.22)  The following is obtained by replacing  € L in Equation (9.22) with (9.20)  2,2aDD a≥ ≥λ λ  (10.23)  The achievable resolution D is consequently equal to the half aperture of the real antenna.   Worth noting here is that this is independent of all other parameters like frequency, range, a s- pect angle, and flying altitude. 
 (12.1). Note that, for a rectangular pulse, Pt is either zero or the peak transmitter power but, for other pulse shapes, the variation with r(or R) is significant. Actual pulses are often approximated by rectangular pulses with widths equal to their half-power widths. 
 8.10. Unsynchronized Replies.-JVhen abeacon isbeing interrogated byseveral radars atthesame time itreplies toall,and thereceiver ofeach interrogator-responsor will respond toallofthese signals. Replies tothe interrogation byaparticular radar aresynchronized and give astationary pattern onitsindicator asdoitsradar echoes; thereplies tointerrogations bythe other radar sets appear tobeunsynchronized and thus show at random onthescreen and aresimilar torandom noise from other causes. 
   PP n  *ULY   ! % !CKER  h%LIMINATING TRANSMITTED CLUTTER IN DOPPLER RADAR SYSTEMS v  -ICROWAVE *OURNAL   VOL   PP n  .OVEMBER  AND REPRINTED IN $ + "ARTON   #7 AND $OPPLER 2ADARS    3ECTION 6 
 461-474, July, 1973.  60. Staelin, D. 
 First, the scope of ECM techniques, in a broad sense, is to impair the target detec - tion and tracking performance of a radar system. Detection performance is measured  by the probability of detection; tracking performance is determined by the probability  of detection and the probability of false alarm as well. Conventional (cell averaging)  CFAR raises the threshold in the presence of noise jamming and reduces the number of  targets detected. 
 7.8 for the circular-waveguide feed whose pat­ tern is shown in Fig. 7.7. The maximum of the curve is relatively broad, so that the optimum  angle subtended by the antenna at the focus is not critical. 
 G. N. Tsandoulis, “Tolerance control in an array antenna,” Microwave J ., pp. 
 The received signal and a portion of the  transmitter heterodyne in the detector (mixer) to yield a difference signal  Figure 3.7 Spectra of received signals. (a) No doppler shift, no relative target motion; (h) approaching  target; (c) receding target.  78INTRODUCTION TORADAR SYSTEMS Afterdetecting andrecognizing thesignal,thefiltermaybeprogrammed tocontinue itssearch infrequency foradditional signals.Oneofthetechniques foraccomplishing thisissimilarto thetracking speed-gate mentioned inSec.5.8,thephase-locked filler,17orthephase-locked loop. 
 SECTION AIRCRAFT AND SHIPS 2ADAR IS ALSO USED BY THE MILITARY FOR RECONNAISSANCE  TARGETING OVER LAND OR SEA  AS WELL AS SURVEILLANCE OVER THE SEA /N THE BATTLEFIELD  RADAR IS ASKED TO PERFORM THE FUNCTIONS OF  AIR SURVEILLANCE INCLUD 
 Rec., 1, pp. 56-60, 1961. (Reprinted in ref. 
 Magnetic PPIUsingAmplijiers.-Figure 13.46 shows the secondary circuit ofamagnetic PPI ofthe resolved–time-base type using the method ofclamping between sweeps. Itissupposed that the synchro ispreceded bythe sweep generator and amplifier ofFig. 13.44, except that thecircuit ofV6ischanged asindicated sothat thefeedback voltage isthat across thesynchro itself. 
 Contradictory require - ments in optimum amplitude distribution for sum and difference patterns exist,19 but,  as with other antenna systems, they may be independently satisfied. The sum and dif - ference patterns are scanned simultaneously. The difference-pattern null in a phased array system gives good beam-pointing  accuracy. 
 However, the curve is a high-dimensional feature that is not easy to use and the degree of anisotropy cannot be quantified by the curve. In this paper, we deﬁne aspect entropy as a descriptor of scattering anisotropy. Aspect entropy ranges from 0 to 1, which corresponds to anisotropic to isotropic. 
 Blassbeam-forming arra~·. R5TheRFbeam-forming principle showninFig.8.26hasbeen usedinthcAt~)lIR_t.aonc-of-a-kind dcvelopmental height-finder radarbuiltfortheFederal Aviation Agency. Waveguide transmission lineswerearranged toserveasthedelaylines. 
 Turyn, “On Barker codes of even length,” Proc. IEEE  (correspondence), vol. 51, p. 
 102.Skolnik, M.I.:LargeAntenna Systems, chap.28of"Antenna Theory, pt.2,"R.E.Collinandf.J. Zucker(eds.),McGraw-Hili BookCo.,NewYork,1969. 103.Simpson, P.1.:Mechanical AspectsofGround-Based Radomes, Chap.12of"Mechanical Engineer­ inginRadarandCommunications," C.J.Richards (ed.),VanNostrand Reinhold Co.,NewYork. 
 For convenience  the range, azimuth, and elevation (r, 0, 4) coordinates of the radar output are converted to  rectilinear (x, y, z) target coordinates to perform the data smoothing and comparison with  prediction. In radar coordinates, the track of a target on a straight-line trajectory is curvilinear  and can generate apparent accelerations. This does not happen when tracking in rectilinear  coordinates. 
 IEEE Trans .. vol. AP-13, pp. 
 ll'ashi11gto11, D.C.. Report 7098, June 25, 1970 (AD 709897).  11. 
 TER MITIGATE THE PRESENCE OF AN INTENSE JAMMER  WITH THE RELATED DISTORTION OF SUM AND DIFFERENCE BEAM SHAPES MAY INTRODUCE ERRORS IN THE CONVENTIONAL MONOPULSE TECHNIQUE  IN PARTICULAR  IF THE JAMMER IS CLOSE TO THE MAIN BEAM  THUS  THE CONVENTIONAL MONO 
 75. Hayes, R. 13.. 
 The  range gate acts as a switch or a gate which opens and closes at the proper time. The range gates  are activated once each pulse-repetition interval. The output for a stationary target is a series  of pulses of constant amplitude. 
 Implementation Considerations.  As discussed above, transformations and tech - niques to reduce the number of degrees of freedom in the STAP solution are important  not only due to processing requirements but also because of the need for sample sup - port on the order of two times the number of degrees of freedom for adequate STAP  performance. The basic hardware requirements for good clutter cancellation remain unchanged  from conventional clutter cancellation architectures—low phase noise, low pulse  jitter, etc. 
 Diffraction.  Energy tends to follow along the curved surface of an object. The  degree of refraction is dependent upon the polarization of the propagating wave and  the size of the diffracting object relative to the wavelength. 
 An important defense-related role of high frequency  (HF) over-the-horizon (OTH) radar is to provide a capability for early warning detec - tion and tracking of air and ship targets. By using the ionosphere as a propagation  medium, skywave  OTH radars can operate at very long distances to achieve detection  and tracking at ranges of 500–3000 km. On the other hand, surface-wave  OTH radars  exploit vertically polarized HF signals (3–30 MHz) and the conductive properties of  sea water to detect targets at ranges limited to about 250 km. 
 T able 7. D3 dataset using different models. Model Accuracy (%) Resnet-50 98.52 Alexnet 96.31 VGG-16 98.46 Densenet-121 98.96 Resnet-34 97.24 The results in Table 7show that with our method, many models can get good performance, and Densenet-121 model have better performance than other popular models, but it may take much time for training. 
 R. J. Barker et al., Modern Microwave and Millimeter-Wave Power Electronics , New York: IEEE  Press and Willey Interscience, 2005, Sec. 
 thescatterers areasymmetrical andbackscatter energy appears inbothorthogonal polarization components. Raindrops maynotalwaysbeperfectspheres. Theirdeviation fromthesymmetrical shape ofaspherewillresultintherellected signalcontaining someenergyinthatpolarization component accepted bytheantenna. 
 The linear FM waveform may also be generated by passitle methods such as by exciting a 3 dispersive delay line with an impulse. The frequency-response function of the dispersive delay  line used for generating the transmitted waveform is the conjugate of that of the pulse-  compression filter. In the special case of the linear FM waveform the same dispersive delay line  that generates the transmitted waveform may be used as the receiver matched filter if the  received waveform is mixed with an LO whose frequency is greater than that of the received  signal. 
 ( b) Oil Tanker misclassiﬁed as Container Ship. ( c,d) are probabilities of three categories. The results in Table 8show that the classiﬁer has a high f1-score for the classes Bulk Carrier. 
 Funding: This work was supported in part by Lockheed Martin. Acknowledgments: The authors would like to acknowledge SenSIP for the center’s valuable contributions to this work.Conﬂicts of Interest: The authors declare no conﬂict of interest. 273. 
 2 19..295.  6. Snlith, R. 
 27-30. July,  1974.  25. 
 Geosci. Remote Sens. 2003 ,41, 507–517. 
   PP n  *ANUARY  ;)N THE LAST TERM OF %Q   IN THIS REFERENCE    THE DOT PRECEDING THE MINUS SIGN SHOULD BE DELETED AND  A SHOULD BE REPLACED BY SIN  A  IN %Q     THE SIGN OF THE FIRST TERM ON THE RIGHT SIDE MUST BE REVERSED=  ! -ICHAELI  h%QUIVALENT EDGE CURRENTS FOR ARBITRARY ASPECTS OF OBSERVATION v  )%%% 4RANS   VOL !0 
 H. Long: F-16 Pulse Doppler Radar (AN/APG- 66) Performance, IEEE Trans., vol. AES-19, pp. 
 36, pp. 237-248,4th qtr.,  1973.  15. 
 ThereisalsopassiveECM,suchaschaff,whichreflectsradarenergytocrcateclutterandfalse targets.Themethods employed tocombatECMarecalledelectrollic COll1lter-CVI/Ilterme(/Sl/res. orECCM. TheseveralformsofECMdirected againstradarmaybecategorized asnoisejamming, deception jamming. 
 3.16, apart ofitreturning tothe recei~f’r tobcamplifiwl and sboff-n onther:idiir scope, The signal strength from land areas issomtIch greater than that returned }JYlf-:~ter surfaces that thciuterpretation ot’hind -\\”atcr bound- :~rirs isthe simplest ofallrcrognition problrms. Inaregion ofhighly indrntcd comtline the prrwntati[)n issostrikingly- simil:w toordinary maps tlmt navi~aticon lJYpilotagc canbeperformed e~”en b}-ill(’x~]t’ric’llceci operators. Situatlfnw ofthi~ tJ-p(> are illllstr:ltml inI;igs. 
 Aeronaut. 97, 440-463 (1985).  2 GEOSAT-A Data Users/Ground System Interface Control Document (ICD) ,  JHUlAPL 7292-9510 Rev. 
 A rear feed not shown is the Cutler feed,9 a  dual-aperture rear feed in which the waveguide is in the center of the dish and the energy is  made to bend 180° at the end of the waveguide by a properly designed reflecting plate. The rear  feed has the advantage of compactness and utilizes a minimum length of transmission line.  The antenna may also be fed in the manner shown in Fig; 7.9c. 
 The receiver frequency-response function, for purposes of this discussion, is assumed to  apply from the antenna terminals to the output of the IF amplifier. (The second detector and  video portion of the well-designed radar superheterodyne receiver will have negligible effect on  the output signal-to-noise ratio if the receiver is designed as a matched filter.) Narrowbanding  is most conveniently accomplished in the IF. The bandwidths of the RF and mixer stages of  the normal superheterodyne receiver are usually large compared with the IF bandwidth. 
 If the grazing angles extend between 3 and 70°, then a 14-satellite constellation in a Walker 14/14/12 configuration provides a continuous global twofold coverage. The inclination angle of each orbital plane is 49.4°. Space Environment. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 gain at low-angles, it is standard practice to install a ground mesh screen; this has the  secondary benefit of avoiding pattern distortion due to inhomogeneities in the soil. 
 The leavesandbranches oftrees,forexample, mighthaveconsiderably different reflecting proper­ tiesatKgband(,.t=0.86cm),wherethedimensions arecomparable withthewavelength. from thoseatVHF(tl=1.35m),wherethewavelength islongcompared withthedimensions. Thegeneralexpression forimprovement factorforanN-pulse canceler withN,=N- I delaylinesis61 (4.27) Antenna scanning modulation. 
 W. L. Grantham, E. 
 z GROUND-PAINTING BYAIRBORNE RADAR BY C.F.J.OVERH.~GE .w~ R.E,CI..\PP Airborne radar equipment has been extmsively used inmilitary aircraft fornavigation bypilotage under conditions ofrestricted visi- bility. The performance ofthese radar sets indisplaying topographic features below the aircraft depends onpoint-to-point variations inthe radar-reflection properties ofthe earth’s surface. The information contained inthe received echo signals isgenerally presented tothe observer asabrightness pattern onanintensity-modulated persistent- screen cathode-ray tube inwhich radial distance from the center cor- responds toslant range orground range, and azimuth torelative ortrue bearing. 
 This rate, 6R, is given by73 QR = c tan ($I2)/RR (25.24) For typical geometries 6/? can vary from T/jxs to O.OP/jxs. These rates and rate changes require an inertialess antenna such as a phased array and fast diode phase shifters. Normally a phased array antenna used for surveillance is pro- grammed to switch beams in increments of a beam width. 
 To propagate  energy within the duct, the angle the radar ray makes with the duct should be small, usually  less than one degree.26•27 Only those radar rays launched nearly parallel to the duct are  trapped. With a surface-based radar, ducting is limited to low angles of elevation so that the  chief eITect is to extend the surface coverage.  Since the angle between the radar beam and the duct direction (as defined by the levels of  constant index of refraction) cannot be greater than about 1 ° if power is to be coupled into an  elevated duct, the radar must usually be at an altitude that permits the required shallow  coupling angles to be achieved. 
 Geophys. Res .,  vol. 76, pp. 
 The state-of-the-art in SAR image processing demonstrates that generating efﬁcient 2CMV products, while accounting for the aforementioned problem cases, has not been well addressed. We propose a methodology to address the aforementioned two problem cases. Before detecting temporal changes, speckle and smoothing ﬁlters mitigate the effects of speckle noise. 
 € Dmin=R0λ 2 (10.35)  The processing which has been illustrated until here, is in practice more difficult due to the  pulsed transmitting signal.  Each rectangular pulse has a spectrum, whose envelope is the Fo u- rier transform of the pulse, and whose linear separation is the pulse sequence frequency.  The  middle frequency of the rece ived signal has a constant offset around f d for the transmitting  signal:   € fd=2v λcosθ (10.36) . 
 After amplification, at intermediate frequency (IF), the sum and difference chan- nels are combined into a single receive channel for routing to the inboard elec- . Ironies assemblies for further processing. The transmitter employs a traveling- wave tube (TWT) with 44 dB gain to amplify the coherent synthesizer output to 50 W of peak power. 
 Viviani, F.; Michelini, A.; Mayer, L.; Coppi, F. IBIS-ArcSAR: An Innovative Ground-Based SAR System for Slope Monitoring. In Proceedings of the IGARSS 2018-2018 IEEE International Geoscience and Remote Sensing Symposium, Valencia, Spain, 22–27 July 2018; pp. 
 49,  pp. 427-447, February, 1961.  64. 
 # #LASS 
   PP n  *ANUARY   7 7 3HRADER  INVENTOR  h3ENSITIVITY 6ELOCITY #ONTROL v 53 0ATENT     *ULY  # 2IFE AND 2 2 "OORSTYN  h3INGLE 
 CO  STYLE FOR THOSE RADARS AND 9AGI ARRAY ELEMENTS FOR  THOSE AT THE HIGHER FREQUENCIES 4HE HIGHER FREQUENCY 5(& PROFILERS TYPICALLY USE EITHER 9AGI OR MICROSTRIP PATCH ARRAY ANTENNAS 4RANSMITTERS ARE GENERALLY IN THE FORM OF HIGH 
 TIONS GIVEN ABOVE 4HE TERM  PSEUDO 
 FREQUENCY AC 
 BASED RADAR OBSERVATIONS OF *UPITERS ICY MOONS 4HE SUBSEQUENT  CLAIM THAT WATER 
 ANGLE CLUTTER SEEN IN A MARINE ENVIRONMENT  )TS SUCCESS IS VERY LIKELY DUE TO ITS RELATION TO  THE 2ICE DISTRIBUTION  WHICH DESCRIBES THE STATISTICS OF STEADY SIGNALS IN NOISE  THUS REFLECTING THE STATISTICS OF hTARGET 
 SEC, 17.4] METHODS OF COMBATING INTERFEREA’CE 685 method issatisfactory only fortransmitting continuous rotation at afairly constant rate. 2.Theangle itself canbetranstitted titerms oftherelative phasesof two sets ofperiodic signals which areusually either sinusoids or pulse trains (Sec. 17.5). 
 POLARIZED ELEMENTS  DRIVEN SIMULTANEOUSLY  n OUT OF . £n°{n  2!$!2 (!.$"//+  PHASE SO THAT THE RADIATED POLARIZATION IS CIRCULAR EITHER LEFT OR RIGHT  4HE RECEIVED  LINEAR POLARIZATIONS ARE MAINTAINED THROUGH THE REMAINDER OF THE SYSTEM TO THE IMAGE PROCESSOR OUTPUT PRODUCTS 4HIS RESULTS IN THE HYBRID 
 Thus, the gains so defined describe the maximum concentration of radi­ ated energy. It is also common to speak of the gain as a function of angle. Quite often the  ordinate of a radiation pattern is given as the gain normalizi;;d to unity and called relative gain. 
 TYPE STEP 
 By injecting test signals of known power, one can  determine the receiver gain transfer function. For polarimetric radars special care  is required.76 It has been demonstrated that by measuring the cross-polar powers in  addition to the solar flux, an accurate estimate of the differential channel calibra - tion can be obtained.77 The AMS held a very successful Weather Radar Calibration  Symposium78 documenting all aspects of meteorological radar calibration. 19.4 SIGNAL PROCESSING To compute the various weather products necessary for forecasting, warning, and other  operational activities, the first three spectrum moments corresponding to received  power, mean radial velocity, and doppler spectrum or velocity width must be estimated. 
 butechoesfrommoving targetsvaryinamplitude fromsweeptosweepataratecorresponding tothedoppler frequency. Thesuperposition of r·T-j__ r---~--------'WJ\Mr----------'WIMJv- (al (b) <--------n------ _L---"" (el Figure4.2(a)RFechopulsetrain;(h)videopulsetrainfordopplerfrequency fd>l/T;(c)videopulse trainfordorrlerfreuqney fd<I/T.. Figure 4.3 (a-e) Successive sweeps of . 
 69 75. February/March, 1975. ll Nnlos. 
 Electrons arcnotintentionally collected bytheanodeasinothertubes; instead, theelectrons areremoved bythecollector electrode (shownontheright-hand sideof thediagram) afterthebeamhasgivenupitsRFenergytotheoutputcavity. Theinputsignalisapplied acrosstheillteractioll gapofthefirstcavity.Low-power tubes mightcontain agridstructure atthegaptoprovide coupling tothebeam.Inhigh-power tuhes,however, thegapdoesnotusuallycontain agridbecause agridcannotaccommodate highpower.(Theabsenceofagriddoesnotseriously impairthecoupling between thegapand thebeam.)Thoseelectrons whicharriveatthegapwhentheinputsignalvoltage isata maximum (peakofthesinewave)experience avoltagegreaterthanthoseelectrons which arriveatthegapwhentheinputsignalisataminimum (troughofthesinewave).Theprocess whereby atimevariation invelocity isimpressed uponthebeamofelectrons iscalledvelocity modl/lat iOIl. Inthedriftspace,thoseelectrons whichwerespeeded upduringthepeakofonecycle catchupwiththosesloweddownduringtheprevious cycle.Theresultisthattheelectrons of thevelocity-modulated beambecome "bunched," ordensity modulated, aftertraveling through thedriftspace.Iftheinteraction gapoftheoutputcavityisplacedatthepointof maximum hunching, powercanbeextracted fromthedensity-modulated beam.Mosthigh­ powerklystrons forradarapplication haveoneormorecavities between theinputandoutput ~.RFcavities~ ~~~a; Interactian gaps Electron beam,[lr===i-:Y Cothod'-}1\1__n~ ~llector\ Ileater~0'..=--=----------=.---=---=--=----- --~- -----=-----------:::::) MOd"OtioViAO~ \IrI oood'""< ~r \V ~I Drift space Electron gunRF RF out . 
 11. D. Ausherman, A. 
 22, 1996, pp. 154–162. 28. 
 135. Retzer, G.: A Concept for Signal Processing in Bistatic Radar, IEEE Int. Radar Conf., pp. 
 T. Ulaby, R. K. 
 In 1940, AMRE, now called the Ministry of Aircraft Production Research Establishment (MAPRE), moved to Worth Matravers, near Swanage in Dorset. The name of this organisation was further changed to the Telecommunications Research Establishment (TRE) in November 1940, still part of the Air Ministry. InMay 1942 TRE moved to Malvern because of the danger of commando raids, fear of German interception of TRE experimental transmissions and vulnerability to bombing on the south coast of England. 
 The near field is followed by the Fresnel regio11. In the Fresnel region, rays from the  radiating aperture to the observation point (or target) are not parallel and the antenna  radiation pattern is not constant with distance. Little application is made of the Fresnel region  in radar. 
 This matter is discussed in Ref. 15, p. 472 ff. 
 T., et al.: A 60 GHz GaAs FET Amplifier, IEEE MTT-S Int. Microwave Symp. Dig., pp. 
 was 100 .ft wi<le and 36 ft high and scanned a I0° beam over a 120° sector.  ;\ major advance in phased-array technology was made in the early 1950s with the  replacement of mechanically actuated phase shifters by electronic phase shifters. Frequency  scanning in one angular coordinate was the first successful electronic scanning technique to be  applied. 
 BAND RADAR LOOKING INTO MODERATE  A  AND CALM  B  SEAS AT A  GRAZING ANGLE  .OTICE THAT THE  APPEAR 
 filters which reduce pulse voltages onthem toalevel that will notinter- fere with communications. The pulse transformer case, being the source ofsome heat, projects outside the airtight compartment. The r-fsystem ofthis unit isshown inFig. 
 The otherimplementation istoinsertaphase s~ifterinonebranchofthedelay-line canceler and adjustitsphasetoshiftthenullofthefrequency response. (Aphaseshift\{Jinonebranchofthe canceler corresponds toafrequency shift2nId=\{J/Tp,whereTp=pulserepetition interval.) Theclutter-doppler-frequency compensation can,insomecases,bemadeopenloopby usingtheaprioriknowledge ofthevelocity oftheplatform carrying theradarandthe direction oftheantenna pointing. Thisismorepractical withashipborne radarratherthan withanairborne radar.Whentheclutter-doppler-frequency compensation cannotbeobtained 100,-----,.----.--,----.---.--.-,.-,-,-----,-----r---.----r---,---,--,.--,--, 0·1m "0 L­a u J? c Q) E Q) >a 0.E O'-- .L...-_---"---_-'--------"------'---'--'--'---'- ----'-_---'_-'----'-----JL-J.--L..J.....J 0001 Figure4.34Effectofanonzero clutterdoppler frequency ontheimprovement factorofathree-pulse canceler. 
 The radar antenna captures a portion of the echo  power. If the effective area of the receiving antenna is denoted A.,, the power P, received by the  radar is  ( 1.6)  The maximum radar range Rmax is the distance beyond which the target cannot be detected. It  occurs when the received echo signal power P,just equals the minimum detectable signal Smin. 
 This potentially makes them extremely stable and reliable, with a resultant  low cost of ownership, therefore, meeting the increasing demands of ship operators.  ch22.indd   16 12/17/07   3:02:35 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 22.1  Considerations  ..................................................  22.5  22.3 SBR System Descriptions  ......................................  22.14  STS Rendezvous Radar  .................................... 
 However, the simulation of such a complex system is a difficult, time- consuming task that sometimes involves the use of ad-hoc programming languages  suitable for simulation. Simulation of a complex system on a digital computer is a technique used for the  analysis, design, and testing of a system whose behavior cannot be easily evaluated  by means of analysis or computation. The procedure essentially consists of reproduc - ing the algorithms of a suitable model of the examined system by means of computer  programs. 
 STABILITY REQUIREMENTS HAVE BEEN MET *ITTER IN THE SAMPLING TIME IN THE !$ CONVERTER ALSO LIMITS -4) PERFORMANCE  )F PULSE COMPRESSION IS DONE PRIOR TO THE !$ OR IF THERE IS NO PULSE COMPRESSION  THIS LIMIT IS   ) *" LOGT TD"    WHERE *  IS THE TIMING JITTER   S IS TRANSMITTED PULSE LENGTH  AND  "S IS THE TIME 
          6 AND ( n     
 Remote Sens. 2005 ,43, 683–694. [ CrossRef ] 5. 
 TRACKING 
 EDGE CONFIGURATIONS  SUCH AS THE ONE ON THE UPPER EDGE OF THE MAIN REFLECTOR IN &IGURE   CAN BE DESIGNED TO MINIMIZE EDGE DIFFRACTION   (OWEVER  THE PRICE  PAID FOR THIS IMPROVEMENT IN PERFORMANCE IS A MUCH LARGER AND MORE COMPLICATED REFLECTOR STRUCTURE. 
 155. R. Fante and S. 
 The PPI picture was also more clearly de ﬁned. The main problem was that tuning of the local oscillator became much more critical and had to be adjusted more frequently to cope with the magnetron frequency drift. It was recommended that the narro wer IF should not be incorporated in ASV Mk. 
 Perhaps the most common manifestation of the principle of the histatic radar is the rhythmic  flickering observed in a TV picture when an aircraft passes overhead, especially if the television  receiver is tuned to a weak channel.  The inherent geometry of the bistatic radar is more suited to a fixed (nonscanning)  fencelike coverage as in Fig. 14.12, as is obtained with fixed antennas generating fan beams. 
 External factors affecting radar  performance include the target characteristics; external noise  that might enter via the  antenna; unwanted clutter  echoes from land, sea, birds, or rain; interference  from other  electromagnetic radiators; and propagation effects due to the earth’s surface and atmo - sphere. These factors are mentioned to emphasize that they can be highly important in  the design and application of a radar. Radar Transmitters. 
 J.: Doppler Radar, Proc. IRE, vol. 37. 
 Three sources of phase ambiguity are common:  frequency dividers, direct digital synthesizers, and voltage controlled oscillators (VCO).  Frequency dividers produce an output signal that can have any one of N phases, where N  is the divide ratio; switching dividers can result in phase ambiguity of 2 p /N. If frequency  dividers are used in the frequency synthesis process, they must be operated constantly  without switching the input frequency or divide ratio to avoid this phase ambiguity. 
 Press, S. A. Teukolsky, W. 
 Taking the three beams as an example, in data collecting, the echo data of target Pi(Xi,Rs)from forward-looking beam is ﬁrstly obtained. When the carrier is located at A, the forward-looking beam center points to the target Pi. At this time, the squint angle is θ, and the beam-width of forward-looking beam is θBW1. 
 SURED SEA CLUTTER  HAVE LED THROUGH THE YEARS TO CONTINUING INQUIRY INTO THE PHYSICAL ORIGINS OF SEA SCATTER AND HOW BEST TO MODEL IT n 4HIS BEING THE CASE  SPECULATION  ABOUT PHYSICAL MODELS WILL BE KEPT TO A MINIMUM IN THE SECTIONS ON THE EMPIRICAL BEHAVIOR OF SEA CLUTTER 4HE PROBLEM OF MODELING SEA SCATTER WILL BE DISCUSSED SEPA 
 April, 1957.  56. kked, R. 
 G. Bath, “A retrospective detection algorithm for extrac - tion of weak targets in clutter and interference environments,” in IEEE Int. Radar Conf ., London,  1982, pp. 
 NOISE TEMPERATURE 0!',4   WHICH IS A MEASURE OF THE SENSITIVITY OF THE RADAR )NCREASING THE OUTPUT POWER OF A 42 MODULE ONLY INCREASES THE TRANSMIT POWER COMPONENT OF THE 0!' PRODUCT (OWEVER  ADDING AN ADDITIONAL 42 MODULE TO THE ARRAY INCREASES EACH OF THE COMPONENTS OF THE 0!' THE TRANSMIT POWER  THE RECEIVE APERTURE  AND THE TRANSMIT GAIN 4HEREFORE  RADARS WITH A "-$ FUNCTION TYPICALLY HAVE A LARGE NUMBER OF ELEMENTS  WHICH RESULTS IN A LARGE APERTURE "ECAUSE A LARGE ANTENNA APERTURE PRODUCES A NARROW ANTENNA BEAMWIDTH  THE VOLUME SEARCH FUNCTION WILL REQUIRE SCANNING A LARGE NUMBER OF BEAM POSITIONS .AVAL SHIPS NEED TO OPERATE IN LITTORAL CLOSE TO LAND  ENVIRONMENTS  AS WELL AS IN  THE OPEN OCEAN 4HE DESIRE TO  OPERATE CLOSER TO LAND REQUIRES S HIPBOARD RADARS TO HAVE  THE CAPABILITY TO REJECT HIGH CLUTTER RETURNS (IGH CLUTTER REJECTION IS USUALLY ACHIEVED THROUGH THE USE OF PULSE DOPPLER WAVEFORMS IN THE FIRST FEW ELE VATION BEAM POSITIONS .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°xx )N ADDITION  MANY OF THE RADAR WAVEFORMS MAY BE DESIGNED TO PROPAGATE OUT TO THE  INSTRUMENTED RANGE OF THE RADAR !S A RESULT  A MAJOR COMPONENT OF THE DWELL TIME AT EACH BEAM POSITION IS THE TIME REQUIRED FOR THE PULSE TO PROPAG ATE TO THE INSTRUMENTED  RANGE AND BACK 4HIS LONG PROPAGATION TIME  COMBINED WITH THE LARGE NUMBER OF BEAM POSITIONS DUE TO A NARROW ANTENNA BEAMWIDTH AND A PULSE DOPPLER WAVEFORM WITH A LARGE NUMBER OF PULSES  RESULTS IN UNSATISFACTORY LONG SEARCH FRAME TIMES WHEN USING A SINGLE BEAM RADAR )F THE ACTIVE ARRAY RADAR IS SIZED FOR LONG 
 4.3 MULTIPLE, OR STAGGERED, PUI.SE REPETITION  FREQUENC1Ess,11-22,s 1.s2  The use of more than one pulse repetition frequency offers additional flexibility in the design of  MTI doppler filters. It not only reduces the effect of the blind speeds [Eq. (4.8)], but it also  aJJows a sharper low-frequency cutoff in the frequency response than might be obtained with a  cascade of single-delay-line cancelers with sin" xf4Tresponse. 
 CIAL ATTENTION TO SIGNAL PROCESSING AND THE INTERPRETATION OF THE RADAR SIGNAL -OREOVER  FEATURES OF THE SEA ENVIRONMENT SUCH AS RAIN  CURRENTS  SLICKS  AND REFRACTIVE ANOMALIES CAN CONFUSE THE RELIABLE SEPARATION OF TARGET RETURNS FROM CLUTTER ARTIFACTS 4HE QUESTION OF MICROWAVE SEA CLUTTER THEORY REMAINS UNSETTLED 4HE MOST POP 
 Broadcasting sends continuous a Sp ay aera  ; nas a Wy  \  Lar ions = Saray si Fi “ Seas rae r A oat: Eee eRe as Ee  THE DIFFERENCE BETWEEN BROADCASTING  AND RADAR  waves in all directions; radar sends short pulses of wave energy in one direction.  Nore. The  in detail, Picture is merely illustrative, and is not to be considered accurate  . 
 The output of the matched filter is not a replica  of the input signal. However, from the point of view of detecting signals in noise, preservjng the  shape of the signal is of no importance. If it is necessary to preserve the shape of the input  pulse rather than maximize the output signal-to-noise ratio, some other criterion must be  employed. 
 There has been at least one example in the past where a major  radar system originally designed with CFAs based on dc operation had to have its dc  operated CFAs replaced during the middle of its development with CFAs that used  conventional pulse modulators. At the beginning of the 21th century, the solid-state modulator  was developed and  began to be used for radar transmitters as either cathode pulsed or modulating anode  pulsed modulators, as well as grid pulsed. Solid-state modulators offer improved trans - mitter performance by allowing a wide variation in parameters (pulse width, pulse  repetition frequency, pulse agility, and pulse-to-pulse consistency). 
 #  USING A SMALL RECEIVING ANTENNA AT 8 AND # BAND  MOUNTED ON A  
 F]~.9.31.—Detail ofradial feedhorn. SEC. 916] OTHER TYPES OF ELECTRICAL SCANNERS 303 %A$ atabout 10cm ndproduces abeam 2°inazimuth by6.5° inelevation, which scans 29°one way inazimuth 10times persecond. 
 An alternative to both cavity and source comparison techniques is the use of a delay line to provide a primary reference for the measurement of phase noise. A method that eliminates the noise contributed by the local oscillator is suggested in the appendix of Ref. 16. 
 42.Chadwick. R.B..andG.R.Cooper: Measurement ofDistributed Targets withtheRandom Signal Radar.IEEETrans.•vol.AES-8.pp.743-750. November, 1972. 
 DETECTION OFRADAR SIGNALS INNOISE375 thevaluesofBrwhichmaximize thesignal-to-noiseratio,(SNR) forvariouscombinations of filtersandpulseshapes.ItcanbeseenthatthelossinSNRincurred byuseofthesenon­ malched filtersissmall. Matched filterwithnonwhite noise.Inthederivation ofthematched-filter characteristic [Eq.(10.15)J, thespectrum ofthenoiseaccompanying thesignalwasassumed tobewhite;that is,itwasindependent offrequency. Irthisassumption werenottrue, the filterwhichmaximizes theoutputsignal-ta-noise ratiowouldnotbethesameasthematched filterofEq.(10.15).It hasbeenshown 1113thatiftheinputpowerspectrum oftheinterfering noiseisgivenby [NlfW, thefrequency-response function ofthefilterwhichmaximizes theoutputsignal-to­ noiseratiois (10.19) Whenthenoiseisnonwhite, thefilterwhichmaximizes theoutputsignal-to-noise ratiois calledtheNWN(nonwhite noise)matched filter.Forwhitenoise[Nj(f)]2=constant andthe NWNmatched-filler frequency-response function ofEq.(10.19)reducestothatofEq.(10.15). 
 62. Nessmith, J. T.: Range Instrumentation Radars, IEEE ELECTRO '76, Boston, Mass., May l l 14,  1976. 
 Van Meter: Detection and Extraction of Signals in Noise from the Viewpoint of  Statistical Decision Theory, J. Soc. Ind. 
 TERS #HAPTER  OF &ARINA   I  THE GAIN MARGIN  A  AND THEN THE GAIN  '! OF THE AUXILIARY  ANTENNA  II  THE BLANKING THRESHOLD  &  AND THE NORMALIZED DETECTION THRESHOLD  @ 4HE A  PRIORI KNOWN PARAMETERS ARE HYPOTHESIZED TO BE THE RADAR SIDELOBE LEVEL  'SL AND THE VAL 
 It is reasonable to suppose, however, that a human observer of a cathode-ray-tube display makes decisions in an analogous manner. That is, the equivalent of a threshold voltage (which would be a luminosity level for the PPI-scope type of display and a "pip-height" level for the A-scope display) exists somewhere in the observer's eye-brain system. This threshold, resulting in a particular false- alarm probability, is probably related to the observer's experience and personality: his or her innate cautiousness or daring. 
 the curvature of the earth cannot be neglected when predicting radar coverage. This  is i:specially true for coverage at low elevation angles near the horizon. The two regions of  interest in radar propagation are the i11ter/ere11ce region and the difl1·actio11 region. 
 A vertical slit in an opaque screen  placed in the focal plane of the spherical lens displays all ranges in a particular direction. The  slit is omset from the origin because of the dc bias that had to be added to the signal at the  input to the CRT in order to record on film. If the slit were placed on the optical axis,  the presence of the dc bias will cause a degraded image because the energy from the bias  overlaps the desired image. 
 Any use is subject to the Terms of Use as given at the website. Civil Marine Radar.  CIVIL MARINE RADAR  22.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 17. R. 
 Radial Velocity.  The radial velocity of a target is obtained from the rate of change  of range over a period of time. It can also be obtained from the measurement of the dop - pler frequency shift. 
 This  makes the radar transmitter work harder. The  difference in decibels (dB) between the pulse power and  average power level is easily calculated using ten times the  log of the pulse width divided by the pulse repetition interval.   Range is therefore limited b y the pulse characteristics and  propagation losses. 
 CAL DOPPLER RADAR CAN BE USED TO DETECT LOCATIONS WHERE NEW THUNDERSTORM DEVELOP 
 ASV Mk. III units; A: scanner type 51; B: TR.3191; C: power unit type 280; D: waveform generator type 26 [Crown copyright, released under OGL v3.0; A5269, MRATHS].Airborne Maritime Surveillance Radar, Volume 1 3-13. the range 15 –35°, equivalent to ranges from about 0.64 nmi to 0.29 nmi when ﬂying at 1000 ft. 
 Radar is used to detect at kast  three different classes of targets over the sea: aircraft, ships, and small objects such as buoys.  (Navigation radars must also see land-sea boundaries in addition to buoys.) The detection of  such targets in the presence of sea clutter generally requires a different design approach for )  each, although there are similarities among them. In brief, a radar required to detect aircraft in  the presence of sea clutter would likely employ MTI (moving target indication); a radar for the  detection or buoys and other small objects on the sea would generally be of high resolution  and employ techniques to prevent receiver saturation by large clutter; and a radar designed to  detect ships could be of moderate resolution since the radar cross section of ships is relatively  large. 
 The instantaneous frequency of the LFM waveform varies  between 1.5 and 2.5 MHz over the pulse duration, as indicated by the reduction in the  spacing of successive positive-going zero crossings of the signal.† LFM Waveform Spectrum.1,2,3 The spectrum of the LFM waveform has a signifi - cant amplitude variation versus frequency for small time-bandwidth products. For large  values of time-bandwidth product, the magnitude of the spectrum approaches rect(  f/B)   u t Tt Te U f f Bj t( ) / | ( ) | ( / )= ≈1 2rect( ) rect forπα TB 1>> (8.6) The LFM spectrum is expressed in terms of the complex Fresnel integral, and the  amplitude variation present for low values of TB is termed the Fresnel ripple .  LFM Waveform Ambiguity Function . 
 Reed, “Theory of adaptive radar,” IEEE Trans ., vol. AES-9, no. 1,   pp. 
 62. Peeler, G. I>. 
 II and designated ARI 5119. ASV Mk. III was in service with RAF 172 Squadron, Chivenor, at the start of March 1943, ﬁtted in Wellington XII aircraft with Leigh Light ( ﬁgure 3.1). 
 TO 
 SCALE EXPERIMENTS IN THE MID 
 The appropriate expression is obtained by noting that the width of the radiated beam, in radians, is given by the ratio XlD whereas the linear width of the beam at range R is the product of this beamwidth and range. These con- siderations lead to the result already written as Eq. (21.6). 
 DEPENDENT LIMITS !LL SUBSYSTEMS SAVE FOR THE ANTENNA  ARE DUAL 
 IZED DOPPLER IE  IN UNITS OF THE "RAGG FREQUENCY  FOR EIGHT RADAR OPERATING FREQUENCIES 4HE PEAK AT ZERO FREQUENCY IS DUE TO A STATIONARY TARGET IN AN ANTENNA SIDELOBE . Óä°ÇÈ  2!$!2 (!.$"//+  FREQUENCIES ABOVE 4HE POSITIVE DOPPLER RESONANT WAVE PEAK IS ABOUT  D" LARGER  THAN THE NEGATIVE DOPPLER PEAK  INDICATING A SEA DRIVEN BY WINDS BLOWING TOWARD THE RADAR 4HE PROCESSING USED IN DEVELOPING THESE DISPLAYS WAS  
 Rept .  9178, 1966. 157. 
 ING BY CONVOLVING TWO WEIGHTING FUNCTIONS 4HE RESULT IS A FILTER WITH SIGNIFICANTLY LESS WEIGHTING LOSS AND LOW FAR 
 Hayne, “Radar altimeter mean return waveforms from near-normal incidence ocean surface  scattering,” IEEE Antennas and Propagation , vol. AP-28, pp. 687–692, 1980. 
 Noise can enter the receiver via the antenna terminals along with the desired signals, or it  might be generated within the receiver itself. At the microwave frequencies usually used for  radar, the external noise which enters via the antenna is generally quite low so that the receiver  sensitivity is usually set by the internal noise generated within the receiver. (External noise is  discussed in Sec. 
 When the antenna is pointing  FIGURE 3. 3 Defining geometry: a�0 = antenna pointing angle; a = line-of-sight angle; q = angle  from antenna centerline; Vg = aircraft ground speed; Vr = radial velocity of point target; VB = radial  velocity along antenna centerline (boresight); y0 = antenna azimuth angle; y = azimuth angle; R =  ground range to point target; and H = aircraft height ch03.indd   4 12/15/07   6:02:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Ó°n  2!$!2 (!.$"//+  4HE TYPICAL DOPPLER RADAR IMAGES PRESENTED BY 46 WEATHER FORECASTERS OFTEN HAVE THE  BIRDS AND BATS AND INSECTS REMOVED BY HUMAN INTERVENTION 4ECHNIQUE  34# WORKS QUITE WELL FOR UNWANTED BIOLOGICAL RETURNS NEAR THE PEAK  OF THE RADAR BEAM  BUT WHEN USED WITH A COSECANT 
 TEROMETER FOR ESTIMATION OF EXTINCTION AND SCATTERING PROPERTIES OF FOREST CANOPIES v  )%%%  4RANS  VOL '% 
 QUENCY RESPONSE ON LINE  OF &IGURE  IS NEITHER AN EVEN NOR AN ODD FUNCTION  SO THE CORRESPONDING IMPULSE RESPONSE IS NEITHER PURELY REAL NOR PURELY IMAGINARY &)'52%   6ARIOUS SIGNALS SAMPLED AT  -(Z  A   -(Z COSINE AND nSINE ,/ SIGNALS    B   -(Z )& TONE  AND C  RESULT OF MULTIPLYING A   SAMPLES BY B  SAMPLES                        
 The weakest  signal the receiver can detect is called_ the minimum detectable signal. The specification of the  minimum detectable signal is sometimes difficult because of its statistical nature and because  the criterion for deciding whether a target is present or not may not be too well defined.  Detection is based on establishing a threshold level at the output of the receiver. 
 18. P. A. 
 SPLITTING   P2 IS  THE CRITICAL PARAMETER ESTABLISHING ACCURACY OF THE  22 ESTIMATE  SINCE  AS IN THE MONOSTATIC  CASE  ITS ERROR IS PROPORTIONAL TO TARGET RANGE ! FULL ERROR ANALYSIS OF %Q  IS GIVEN  IN 3ECTION  OF 7ILLIS  .O BISTATIC RADAR OPERATING AUTONOMOUSLY HAS BEEN SHOWN TO  PROVIDE ADEQUATE LOCATION OF AIR OR SPACE TARGETS WITHOUT EMPLOYING RECEIVE APERTURES COMPARABLE IN SIZE TO MONOSTATIC RECEIVE APERTURES USED FOR THOSE PURPOSES )N THE SPECIAL CASE OF A BISTATIC RADAR USING THE DIRECT RANGE SUM ESTIMATION METHOD   WHEN 2 4   22 y , %Q  CAN BE APPROXIMATED AS   2C4 2 2 $RT  SINP    4 WO EXAMPLES ARE A RECEIVER OPERATING IN AN OVER 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 The variable phase shifter is then programmed to account for this additional inser - tion phase. With a spherical or quadratic law of insertion phase variation, as obtained  with optical-feed systems (Section 13.8), the reductions in peak quantization lobes  are equivalent to adding 1 bit to the phase shifters in a 100-element array, 2 bits in a  1000-element array, and 3 bits in a 5000-element array. 
 It has been claimed that a dopplcr navigation  system based on this principle can provide 150 dB of isolation, the amount necessary to  operate at altitudes of 50,000 ft.49  The frequency band from 13.25 to 13.4 GHz has been allocated for airborne doppler  navigation radar, but such radars may also operate within the band from 8.75 to 8.85 MHz.  The doppler navigator over land can provide a measurement of ground speed with a  standard deviation of from 0.13 to 0.5 percent. 55 The standard deviation of the drift angle can  be less than 0.25°. 
 TION BEAM  CAN SIGNIFICANTLY INCREASE THE PROBABILITY OF CONFIRMATION  &URTHERMORE   THE CONFIRMATION DWELL SHOULD BE TRANSMITTED AS SOON AS POSSIBLE TO MAINTAIN A 3WERLING  ) FLUCTUATION MODEL 4HAT IS  IF THE TARGET WAS ORIGINALLY DETECTED WHEN THE TARGET FLUC 
 SCALE SURFACE ROUGHNESS )N THE LIMIT    &)'52%    4HE HYBRID 
 Firstly, the DEM image of the scenes is acquired by interference with the ArcSAR slant range images. The acquired DEM image is on the slant range. However, we require the DEM image on the ground range to assist ArcSAR imaging. 
 From this figure, it is seen that the direct conversion approach will fail  whenever a value of M, which is located halfway between the optimum values, is used. At the A/D converter output, the signal samples are still real valued. To be able  to extract the complex envelope corresponding to the positive part of the spectrum,  2⋅ −+A f f ( )IF, it is necessary to shift the spectrum at the A/D converter output   down in frequency by the amount fIF. 
 Because ofthephaserelationships between thelobesofthedifference patternandthesumpattern,theresultisanapparent forward displacement ofthepatternon thefirsttransmission, andadisplacement totherearonthesecondtransmission. Whenthe gainsofthesumanddifference channels areproperly adjusted, andwhenthedistance between thephasecentersofthetwoantenna beamsis2TpVxthecombined sumanddifference p=llterns onsuccessive pulsesilluminate thesameregionandtheantenna appears stationary.SIl (The factor2appea'rs inthedistance between phasecenters.asaresultofusingbothfeedsfor transmission. Thephasecenterontransmit ishalf-way between thetwofeeds,andthephase centeronreceivealternates fromonefeedtotheother.)Astheantenna pointing-direction changes fromtheporttostarboard sideofthevehicle,thesignofthedifference signalmustbe reversed tokeepthedisplaced beamsintheproperorientation. 
 V . Gurevich, Nonlinear Phenomena in the Ionosphere,  New York: Springer-Verlag, 1978. 60. 
 DENT 4HE THIRD CATEGORY OF USE IS FOR RADAR ENHANCEMENT OF SMALL TARGETS  SUCH AS PLEA 
    
 ANE-8, pp. 19 27, March. 1961. 
 IRE, vol. 47, pp. 821-828, May,  1959. 
 17.6. For example, let us assume R = 100 km, V = 180 m/sec (350 kts), qsq = 0, and dcr =   1 m. For f = 10 GHz (X band, l = 0.03 m), tA = 8.3 sec, and the fractional bandwidth B/fo =   0.015. 
 Inmostcasesofpractical interest,theearth'ssurfaceandthemedium in whichradarwavespropagate canhaveasignificant effectonradarperformance. In-some instances thepropagation factorsmightbeimportant enoughtoovershadow allotherfactors thatcontribute toabnormal radarperformance. Theeffectsofnon-free-space propagation on theradarareofthreecategories: (1)attenuation oftheradarwaveasitpropagates through the earth'satmosphere, (2)refraction oftheradarwavebytheearth'satmosphere, and(3)loht' structure causedbyinterference between thedirectwavefromradartotargetandthewave whicharrivesatthetargetviareflection fromtheground. 
 •  May be a driver if  field deployment is  required.•  Typically not a  major driver.•  Typically a  significant driver. •  Could be a major  driver depending  on size of antenna  and platform.•  A major driver; launch  costs are very high and  are driven by available  volume and mass for  radar payload. •  Use of light weight  materials is important. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 1.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 REFERENCES  1. 
 vol. 66, pp. 563-583, May, 1978. 
 IEEE, vol. 79, pp. 839–849, 1991. 
 pp. 515-529. July, 1970. 
 The output of each doppler filter is envelope-detected and processed through a cell- averaging constant false alarm rate (CA-CFAR) processor to suppress residues due to  range-extended clutter that may not have been fully suppressed by the filter . As will be discussed later in this chapter, the conventional MTI detection system  often relies on a carefully controlled dynamic range in the IF section of the radar  receiver to ensure that clutter residues at the MTI output are suppressed to the level of  the receiver noise or below. This limited dynamic range, however, has the undesirable  effect of causing additional clutter spectral broadening, and the achievable clutter sup - pression is consequently reduced.FIGURE  2.8 Processing of Primitive Target detections and Radar Target Reports in MTD IIPRIMITIVE TARGETS INPUT BUFFER ADAPTIVE AMPLITUDE CENSORING PRIMITIVESTHRESHOLDING CENSORING MAP UNIT CORRELA TION OUTPUTS DISPLA YABLE TARGET REPOR TS AND WEA THER CONT OURSINTERPOLA TION ADAPTIVE AMPLITUDE CENSORING RADAR TARGET REPOR TS TO SURVEILLANCE PROCESSORTARGET LO AD/ FALSE-ALARM CONTR OLLERRADAR TARGET REPOR TS ASSOCIA TE TRACKS WITH TARGET REPOR TS UPDATE TRACKS WITH NEW DA TA OR COAST OR DR OP TRACKCORRELA TE TARGET REPOR TS WITH TRACK DISPLA Y TARGET REPOR T IF ASSOCIA TED WITH TRACK IN ST ATE 3 INITIA TE TRACK FILES WITH UNUSED TARGET REPOR TS DISPLA YASSOCIA TION CORRELA TION TRACK UPD ATE TARGET OUTPUT/DISPLA Y 2-LEVEL WEA THER CONT OURS OUTPUT TRACK INITIA TION ch02.indd   8 12/20/07   1:42:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Although theundesirable transient effectsofarecursive filtercanbereduced tosome extent,otherapproaches toMTIfiltering areoftendesired.Onealternative thedesigner has available istheuseofmultiple pulse-repetition frequencies forachieving thedesiredMTIfilter characteristics, asdescribed next. 4.3MULTIPLE, ORSTAGGERED, PULSE REPETITION FREQUENCIES8,1 7-22,81,82 Theuseofmorethanonepulserepetition frequency offersadditional flexibility inthedesignof MTIdoppler filters.Itnotonlyreducestheeffectoftheblindspeeds[Eq.(4.8)],butitalso allowsasharperlow-frequency cutoffinthefrequency response thanmightbeobtained witha cascadeofsingle-delay-line cancelers withsin"1tfdTresponse. Theblindspeedsoftwoindependent radarsoperating atthesamefrequency willbe different iftheirpulserepetition frequencies aredifferent. 
 For a review of some of the approaches the reader should consult Fung's summary in Ref. 50 and papers by Kong, Lang, Fung, and Tsang. These models have been used reasonably successfully to describe scatter from vegetation,51 snow,52 and sea ice.53 Models of straight vegetation such as wheat in terms of cylinders have had some success.2 Corner-reflector effects have been used to describe strong returns from buildings at nonnormal incidence angles.54 Other specialized models have been used for particular purposes. 
 LAYER WIND PROFILERS ARE TYPICALLY USED FOR  AIR POLLUTION MONI 
   PP !n!  3EPTEMBER    * 2 0OWELL  h4ERRAIN )NTEGRATED 2OUGH %ARTH -ODEL 4)2%-  v 2EP 4. 
 ,  Ê 1- 
 AP-14, pp. 405-406, May 1966. 44. 
 OF 
 The most widely used operational systems have, over the years, employed CW semiactive homing. Since the active systems differ only by virtue of the presence of the illuminator-transmitter on board the missile, a discussion of the semiactive sys- tem can be easily extended to cover the active type as well. Similarly, passive homing can be considered a subset of the semiactive. 
 SHIFTED PROPORTIONALLY TO THE RADIAL VELOCITY BETWEEN THE RADAR PLATFORM AND THE TARGET 4HE TWO 
 15.11.) The lock-pulse amplifier is gated off just before the end of the transmitted pulse because a magnetron emits a certain amount of noise during the fall of the high-voltage pulse applied to it, and this noise can prevent perfect locking of the coho. The received signals are mixed with the stalo and amplified in a linear-limiting amplifier. (In some implementations the limiting is not deliberately provided. 
 (16.3)] Tp = interpulse periodANTENNA ELEMENTS NSWITCH ETWORK CORPORATE FEED TERMINATIONS TERMINATIONS . FIG. 16.11 Phaser diagram showing the return from a point scatterer due to platform motion. 
 Also, just as in tube-type transmitters, energy management is still crucial.  Each dc power supply must have a capacitor bank large enough to supply the energy  drawn by its solid-state modules during an entire pulse, and each power supply must  recharge its capacitor bank smoothly between pulses without drawing an excessive  current surge from the power line. As a result of unavoidable losses in combining the outputs of many solid-state  devices, it is especially tempting to avoid combining before radiating, since combining  in space is essentially lossless. 
 I I I I/' II/// I I'  I ;II//// <.,I I I / I I ,1 I I/ -'-....  0-1~~~~~~~~~~~~~~~~~~~~~~~~  1·0 10 100 1000  Antenna diameter -ft  Figure 5.19 Lowest servo resonant-frequency as a function of antenna diameter for hemispherical scan­ ning raraboloid reflector antennas. (Based 011 measurements compiled by D. 
 The difference frequency or intermediate frequency (IF) must be  derived from an I/Q mixer pair if the information equivalent to a time-domain repre - sentation is required (i.e., to reconstitute an impulse), as a single-ended mixer only  provides the modulus of the time-domain waveform. The basic FMCW radar system  is particularly sensitive to certain parameters. In particular, it requires a high degree  of linearity of frequency sweep with time to avoid spectral widening of the IF and  hence degradation of system resolution. 
 Equating  Eqs. (2.24) and (2.25), we get  1 V}  Tra = BIF exp 2t/lo (2.26)  A plot of Eq. (2.26) is shown in Fig. 
 16. A. A. 
 This technique can be used  to measure RF output power, receive gain, and phase and attenuation bit accuracy.  These measured values are then compared with reference values. A major disadvantage  of this technique is that it requires significant additional hardware, including a separate  built-in test (BIT) manifold. 
 135. Ref. 37, vol. 
 (7) In Equation (7), Hsis the maximum altitude to which the TEC is measured, and in this paper, it is the altitude of PALSAR. Integrating the right side of Equation (7) while recalling Equation (3), we can obtain /integraldisplayHs hmF2e1−z−e−zdh=HT/integraldisplay Hs−hmF2 HT 0e1−z−e−zdz=HT/parenleftbigg exp/parenleftbigg 1−e−Hs−hmF2 HT/parenrightbigg −1/parenrightbigg . (8) 203. 
 38.Nicholls, L.A.:Reduction ofRadarGlintforComplex Targets byUseofFrequency Agility,IEEE TrailS.,vol.AES-Il,pp.647649. July.1975.(Seealsocomment onp.325ofref.85.) 39.Sims.R.J.•andE.R.Graf:TheReduction ofRadarGlintbyDiversity Techniques. IEEETrans.•vol. 
 G., and J. R. Forrest: Principles of Independent Receivers for Use with Co-operative Radar Transmitters, Radio Electron. 
 TRATES THE ENERGY IN THE FREQUENCY SPECTRUM OF THE PULSE TRAIN AROUND DISTINCT SPECTRAL LINES  SEPARATED BY THE PULSE  REPETITION FREQUENCY 02&  4HIS  SEPARATION INTO SPECTRAL  LINES ALLOWS FOR DISCRIMINATION OF DOPPLER SHIFTS $OPPLER RADARS USING PULSED TRANSMISSIONS ARE MORE COMPLEX THAN #7 RADARS  BUT  THEY OFFER SIGNIFICANT ADVANTAGES -OST IMPORTANT IS THE TIME GATING OF THE RECEIVER #HAPTER     $AVID ( -OONEY AND 7ILLIAM ! 3KILLMAN WROTE THIS CHAPTER FO R THE FIRST EDITION   7ILLIAM ( ,ONG  JOINED THE AUTHORS FOR THE SECOND EDITION   *OHN 0 3TRALKA AND 7ILLIAM ' &EDARKO UPDATED THE MATERIAL  FOR THIS EDITION o  4O ASSIST THE READER  ABBREVIATIONS USED THROUGHOUT THIS CHAPTER ARE DEFINED IN A LIST AT THE END OF THE CHAPTER. 
 †  In the first two editions of this Handbook, the chapter on SAR was written by Dr. Louis J. Cutrona, who is now  deceased. 
 ch10.indd   28 12/17/07   2:19:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. The Radar Transmitter. 
 The closed-loop action will drive the weight so that the average correlation of the output V0 and each input V1 approximates the value of the quiescent weight. (V*fV0) « Wql for / = 1 to 27V (V*£WjVj) - Wql *(V*iVj)Wj - Wql (16.23) where ( ) indicates the time average. If we define the N values of each de- layed variable by extending the subscript range over N + 1 to K, where K = 2N9 and define mtj = (V*/ V7-), we have the set of equations /H11W1 + W12W2 + • • • + mlKWK = Wql M21W1 -f m22W2 + • • • + m2KWK = W^2DIGITALRECEIVERINPUTLOGIC MULTIPLIER CONJUGATION ADDER MULTIPLIERLOW-PASSFILTERAMPLIFIER ADDER MULTIPLIERLOW-PASSFILTERAMPLIFIER ADDER CONJUGATION INTERPU LSE-PERIOD BUFFER MULTIPLIER . 
 Ricardi. L. J., and L. 
 W., and P.A. Loth: A Monopulse Antenna Having Independent Optimization of the Sum  and DilTerence Modes, I RE C01w. Rec., l, pp. 
 WAVE ECHOES AT LOW GRAZING ANGLES ARE NEARLY AS SIGNIFICANT AS SPECULAR ECHOES AT NORMAL INCIDENCE 4IP  %DGE  AND #ORNER $IFFRACTION  3CATTERING FROM TIPS  EDGES  AND CORNERS IS LESS  SIGNIFICANT THAN SPECULAR ECHOES AND THUS ARE WORRISOME TO THE DESIGNER ONLY WHEN MOST OTHER SOURCES OF ECHO HAVE BEEN SUPPRESSED 4HE ECHOES FROM TIPS AND CORNERS ARE LOCALIZED AND TEND TO INCREASE WITH THE SQUARE OF THE WAVELENGTH  NOT THE SIZE OF ANY SURFACE FEATURE 4HUS  THEY BECOME PROGRESSIVELY LESS IMPORTANT AS THE RADAR FRE 
 1189, July, 1954.  13. Trunk, G. 
 3.19  Filtering of the Entire Radar System  ...................  3.19 Definitions  .........................................................  3.20 Approximations to Ma tched Filters  ..................... 
 2. V . Granatstein, R. 
    
 BIASED  AND COLLECTOR CURRENT IS DRAWN FOR LESS THAN HALF OF AN 2& CYCLE #OLLECTOR CURRENT IS DRAWN ONLY WHEN THE INPUT VOLTAGE EXCEEDS THE REVERSE BIAS ACROSS THE INPUT AND THE OUTPUT VOLTAGE IS DEVELOPED ACROSS A RESONANT 
 tile isolation between transmitting and receiving antennas is made sufficiently large so  as to reduce to a negligible level the transmitter leakage signal which arrives at the receiver via  +he coupling between antennas. The beat frequency is amplified and limited to remove any  amplitude fluctuations. The frequency of the amplitude-limited beat note is measured with a  cycle-counting frequency meter calibrated it1 distance. 
 When it was introduced, the Reggia-Spencer phase shifter had a higher figure of  merit (defined as the degrees or phase shift per dB ofloss) than previous analog ferrite phase  shifters, and was more compact. Since the rod of ferrite is located at the center of the guide out  of contact with the walls, there is no means for dissipation of heat other than by radiation. This  lack or a convenient thermal path to dissipate heat limits its power handling capability. 
 and many kinds of clutter and weather echoes. The Rayleigh density function is  2x ( x2 ) p(x)= 2 exp -2 <x >av <x >av x~O (2.17)  This is plotted in Fig. 2.2c. 
 M. Aumann, A. J. 
 A block diagram of ASV Mk. VIB is shown in ﬁgure 4.15 [6]. 4.4.1 AFC The need for regular manual tuning of the klystron local oscillator was an additional load on the radar operator and a cause of loss of performance when done incorrectly or neglected. 
 Icecoatingareflector surfacedoesnotusuallycausea problem. Wheniceisintheprocessofmelting, however, thewatersurfacecandistortthe patternandinsomeinstances cancompletely destroythemainbeam. 7.10STABILIZATION OFANTENNAS14 •• Iftheradarplatform isunsteady, aswhenitislocatedonashiporanaircraft, theantenna pointing mustbeproperly compensated forthisundesired motion. 
 CLOPEDIA OF %##- TACTICS AND TECHNIQUES CAN BE FOUND IN THE LITERATURE   -ANY OTHER  REFERENCES DESCRIBE THE %##- PROBLEM  AMONG WHICH 3LOCUMB AND 7EST  -AKSIMOV  ET AL  'ROS ET AL  AND *OHNSON AND 3TONER ARE WORTH NOTING  4!",%  %##- 4ECHNIQUES 6ERSUS %#- 4ECHNIQUE #OUNTERED  2EPRODUCED WITH PERMISSION  FROM 3LOCUMB AND 7EST Ú !RTECH (OUSE  AND ' 6 -ORRIS  2ADAR  3UBSYSTEM %##- 4ECHNIQUE%#- 4ECHNIQUE #ATEGORY #OUNTERED .OISE&ALSE 4ARGET2ANGE 'ATE 0ULL /FF6ELOCITY 'ATE 0ULL /FF !NGLE !NTENNA RELATED,OW OR ULTRA 
 IEEE Int. Radar Conf., pp. 17-22, Washington, 1985. 
 IEEE Signal Process. Mag. 2008 ,25, 21–30. 
 PULSED 3ECTION    THERE IS  AN INSTANT DURING THE RISE AND FALL OF VOLTAGE WHEN THE BEAM VELOCITY BECOMES SYNCHRO 
 Ward, G. R. Jiracek, and W. 
 For shipborne use, a minimum of four aper- tures appears desirable since, with pitch and roll, more than hemispherical cov- erage is necessary. The antennas may be positioned as shown in Fig. 7.1, permitting a view that is unimpeded by the central superstructure. 
 Most modern meteorological radars, however, use digital averaging along with digital color displays for added quantitative precision. Note that when the logarithm is averaged, the estimate will be biased downward by as much as 2.5 dB.45 This bias must be removed in order to accurately estimate the received signal power. For doppler radars it has been common to use both linear and logarithmic receiv- ers, with the log channel used for reflectivity estimation and the linear channel for doppler parameter estimation. 
 114,  no. 3, pp. 321–326, March 1967. 
 ri.: Ohjcct IJctcction System. C1.S. Patent no. 
 on Geoscience and Remote Sensing , vol. 29, no. 4, pp. 
 &- RANGING AS IN THE (273 WAVEFORM OR  - 
 638 MOVING TARGET INDICATION [SEC. 16.5 itkalso difficult ifthestable r-foscillator istobelocked, because ofthe high Qrequired tomake the oscillator stable. Locking acoherent i-f oscillator iseasy since the Qcan besmaller byafactor of100 forthe same allowed rate offrequency change. 
 Week Space Technol., May 21, 1979. 29. U.S. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar.  SYNTHETIC APERTURE RADAR  17 .316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 For a “single-frequency” pulse of wavelength l, the difference in the phases of the echoes  received from the point target observed by the two antennas is (from Figure 17.14)  ∆φπ λπ ψ λ11 2 2= =ns nLsin (17.53) We now consider the same antennas A and B observing a second point target b that  is a distance h above the flat ground also at range R; the radar line-of-sight (LOS) inter - sects the parallel to the flat ground at grazing angle y2. 
 August, 1965. .J  53. Ksienski, A. 
 This radar system will include  intelligent decision making for scanning and tracking important low-level atmospheric  features that are deemed critical for the aviation, weather forecasting, transportation,  and local emergency response users. The CASA radars can communicate with each  other for collaborative use of the data and adaptively change their operating param - eters to best meet the prescribed needs at a given time. Depending on the final costs  of deployment and operation, CASA networks may be developed only around critical  areas such as urban areas, airports, etc. 
 Hamming b. 3:1 "taper ratio" cos2 (ir/75) cos3 (ir/75) COS4 (TT/75) Triangular: 1 - 21/1/5Pedestal height H,% 100 11 8 33.3 O O O OSNR loss, dB O 1.14 1.34 0.55 1.76 2.38 2.88 1.25Main-lobe width, -3dB 0.886/5 1.2/5 1.25/5 .33/5 .09/5 .46/5 .66/5 .94/5 .27/5Peak sidelobe level, dB -13.2 -40 -40 -42.8 -25.7 -31.7 -39.1 -47 -26.4Far sidelobe falloff 6 dB/octave No decay 6 dB*/octave 6 dB/octave 6 dB/octave 18 dB/octave 24 dB/octave 30 dB/octave 12 dB/octave . PEAK SIDELOBE LEVEL (decibels) (c)FIG. 
 : a ~02 0 0“1°2“3“4-5“6“7“0“ Anglewth hcmzontal FIG.2.10.—Reflection bywater at3000 Me/see. Curve a:amplitude ofreflection coef- ficient, vertical polarization; Curve h;phase shift atreflection, vertical polarization; Curve c:amplitude ofreflection coefficient, horizontal polarization. Phase shift forhorizontal polarization is180°throughout range shown. 
 TRACING  &OR MANY /4(2 PURPOSES  IT SUFFICES  TO EMPLOY A RAY 
 AES-6, pp. 629-635, November, 1970.  79. 
 £Î°{Ó  2!$!2 (!.$"//+  CENTER 
 46, pp. 1 14, 1 15, 1 17. Nov. 
 The developed procedure is able to perform simulations under di ﬀerent geometric and radiometric SAR conﬁgurations, and di ﬀerent wind conditions (speed and direction). Results were validated by using real SAR data provided by ERS-2 and ENVISAT satellite missions. This kind of tool results very useful to understand how radar and wind characteristics impact on the eddy features in SAR images, and thus to support their interpretation and study. 
 Multiple PRFs may  be used to move the target with respect to the sidelobe clutter in the range-doppler map,  thus avoiding completely blind ranges or blind frequencies due to high clutter levels. This  relative motion occurs due to the range and doppler foldover from range and/or doppler  ambiguities. If one PRF folds sidelobe clutter and a target to the same apparent range and  doppler, a sufficient change of PRF will separate them. 
 V an Brunt, The Glossary of Electronic Warfare , Dunn Loring, V A: EW Engineering, Inc., 1984. 12. Department of Defense, Joint Chiefs of Staff, Dictionary of Military and Associated Terms , JCS  Pub-1, September 1974. 
 The  sphere is a good mechanical structure and offers aerodynamic advantage in high winds.  Precipitation particles blow around a sphere rather than impinge upon it. Hence snow or  other frozen precipitation is not readily deposited. 
 12.9. The diode isusually atube such asthe6H6 orthe6AL5, although many other tubes have been used and recently crystals have been developed forthe purpose. The i-fbypass condenser Cusually has around 10 p~fofcapacity; itmust beconsiderably larger than theplate-to-cathode capacity ofthediode togetgood detector efficiency, but itmust notbeso To,i~m large astospoil the high-frequency ~ ‘- mL2 ~mplifier response ofthevideo amplifier. 
  
 &- ,&-  IS A COMMON WAVEFORM USED IN  OPERATIONAL HIGH 
 15.10] COMPONENTS DESIGN 607 1. 2. 3.Azimuth angle ofbeams does not shift with achange inwave- length. 
 LIKELIHOOD DETECTION OF UNRESOLVED TARGETS AND  MULTIPATH v )%%% 4RANS  VOL !%3 
 Sig. Proc ., vol. 45, pp. 
 The bandwidth must bechosen to provide sufficiently rapid transient response sothat the details ofthe signals will bepreserved; butitmust notbesogreat astodecrease unduly the signal-to-noise discrimination. Inmany cases, special design char- acteristics enhance the discrimination ofcertain kinds ofecho incom- parison toother undesired echoes ortoradiations from other transmitters. The indicating equipment, which isalmost entirely responsible for the purely geometrical aspects ofthe display problem, must share with the receiver the responsibility forthe discernibility ofthe signals with respect tonoise, interference, and signals from other targets. 
 TIONS FOR FREQUENCY AND TEMPERATURE VARIATIONS 3OLID 
 1.Continuous a-fsignals can beused, the information being carried interms oftheamplitude, thefrequency, orthephase with respect toafixed reference. Uptothe present time this technique has been very little used. 2.Pulse-timing techniques can beapplied. 
 14.19  14.8 Miscellaneous CW Radars  .....................................  14.20  CW Proximity Fuzes  ..........................................  14.20 Police Radars  .................................................... 
 The calibrated signal may be fed through the re- ceiver at a time when the transmitter is off. Figure 12.12/? shows a similar ar- rangement in which the signal from the transmitter is attenuated a known amount and used to check the receiver. By comparing the output from the attenuated transmitter signal with that received from the ground, the scattering cross section may be determined without actually knowing the transmitted power and the re- ceiver gain. 
 60. Siegel, K. M.: Bistatic Radars and Forward Scattering. 
 [ CrossRef ] 6. Stojanovic, I.; Mujdat, C.; William, K. Joint space aspect reconstruction of wide-angle SAR exploiting sparsity. 
 The name.isderived fromtheanalogous actionofplacingaheavyconductor, likeacrowbar, directlyacrossthecapacitor bank.Hydrogen thyratrons, ignitrons, andspark-gaps havebeen usedasswitches. Thesuddensurgeofcurrentduetoafaultinaprotected powertubeissensed andthecrowbar switching isactuated withinafewmicroseconds. Thecurrentsurgealso causesthecircuitbreakertoopenanddeenergize theprimary sourceofpower.Crowbars are usuallyrequired forhigh-power, hard-tube modulators becauseofthelargeamounts ofstored energy.Theyarealsousedwithd-coperated crossed-field amplifiers andmod~anode pulsed linear-beam tubeswhichareconnected, directlyacrossacapacitor bank.Theline-type modu­ latordoesnotusuallyrequireacrowbar sinceitstoreslessenergythanthehard-tube modula­ toranditisdesigned todischarge safelyallthestoredenergyeachtimeitistriggered. 
 Rec., pp. 330-339, Arlington, Va., May 6-9, 1985. (IEEE Cat. 
 In general, the magnitude of the coupling is influenced by the distance between the elements, the pattern of the elements, and the structure in the vicinity of the elements. For example, the radiation pattern of a dipole has a null in the 0 = ± 90° direction and is omnidirectional in the 0 = 0° plane. Therefore it can be expected that dipoles in line will be loosely coupled and parallel dipoles will be tightly coupled. 
 LS-CS-Residual (LS-CS): Compressive Sensing on Least Squares Residual. IEEE T rans. Signal Process. 
 WAY PROPAGATION ALLOWS RADAR INTERCEPTION AT FARTHER RANGE THAN OWN PLATFORM DETECTION 2EQUIRED SENSITIVITY VALUES RANGE FROM n D"M D" MILLI7ATT WITH RESPECT TO THE ISOTROPIC  TO n D"M %3- IS THE MOST COMPLEX SYSTEM AND USUALLY COMPRISES THE CAPABILITY TO PRODUCE A PICTURE OF THE COMPLETE ELECTRONIC ORDER OF BATTLE IN ITS DEPLOYMENT AREA AND ALERT FUNCTION 4HIS KIND OF SYSTEM IS ABLE TO DETECT AND ANALYZE EMITTER WAVEFORMS AND SCANNING PATTERNS 4HE REACTION TIME FOR THE RECONNAISSANCE OF THE OPERATIONAL ENVIRONMENT MAY BE LESS THAN  S  THOUGH DANGEROUS EMITTERS AND ALERT FUNCTIONS CALL FOR TIGHTER CONSTRAINTS 2EQUIRED SENSITIVITY RANGES FROM n D"M  TO BETTER THAN n D"M  %,).4 SYSTEMS  ARE SIMILAR TO %3-  BUT MAY NOT REQUIRE  PROBABILITY OF INTERCEPT 4HE REACTION TIME MAY BE MINUTES OR HOURS 4HE  PURPOSE IS NOT TO DETECT EMIT TERS AS SOON AS THEY  SWITCH ON IN THE OPERATIONAL ENVIRONMENT  BUT TO PROVIDE DETAILED CHARACTERISTICS OF EMITTERS TO ALLOW THE GENERATION OF AN IDENTIFICATION DATABASE FOR 272 AND %3- SYSTEMS %,).4 SYSTEM SENSITIVITY MAY REACH n D"M  BUT THEY DONT NEED TO PRO 
  
 MOTION - WAVELENGTHS/INTERPULSE PERIOD FIG. 16.27 Adapted and unadapted improvement factor as a function of normal- ized antenna motion per interpulse period; 16-element (half-wavelength spacing), two-pulse space-time adaptive processor; antenna array aligned to perpendicular to the ground track. the performance when the antenna is pointing abeam. 
 At shorter ranges, clutter increases with radar altitude  since the clutter patch size on the ground increases. While Figure 4.15 is for a medium- PRF radar, similar curves result for a high-PRF radar. Also shown in Figure 4.15 is the single-scan probability of detection Pd versus  range for a given RCS target in a receiver with unlimited dynamic range. 
 For each SAR  or DBS geometry, the transmitted pulse width, pulse repetition interval, and pulse  compression ratio must be calculated. One possible set of selection criteria is given  in Eq. 5.4.45 Usually, the last range ambiguity before the range swath is chosen to be outside  the main beam, far enough to be at least 20 dB down, including R4 effects. 
 In the geodesic analog of a two-dimensional Luneburg lens the  variation in dielectric constant is obtained by the increased path length for the RF energy  traveling in the TEM mode between parallel plates.64--67 The result is a dome-shaped parallel­ plate region as shown in Fig. 7.22.  Other types of lenses based on the principle of nonuniform index of refraction have been  <lcscrihed.43·60·6R Homogeneous spherical lenses with uniform dielectric constant are also of  interest69 71 if the index of refraction is not too high and if the diameter is not greater than  about 30k They can be competitive to the Luneburg lens, especially for high-power  applications. 
 MUTH BEAMWIDTH  \\QQq"   THE MAIN 
 SCALE 2#3 WILL BE  LOG   r      D" HIGHER THAN THOSE CHARTED IN THE FIGURE IE  HIGHER BY THE  SQUARE OF THE INVERSE SCALE FACTOR  7E SUSPECT THAT NOSE 
 \ 1 · Double -rounded cone  -30  40 -M ""--Circular ogive  -so---~~'--~-'-~~~~~---'~~--'~~ ........ ~~--'  0 0 4 0 8 12 1 6 2.0 2.4  Oiomefer in wavelengths Figure 2.13 Radar cross section of  a set of 40° cones, double-backed  cones, cone-spheres, double­ rounded cones, and circular ogives  as a function of diameter in wave­ lengths. (From Blore,21 IEEE  Trans.) . 
 W.: NASA Ground-Based and Space-Based Laser Ranging Systems. Proc. Soc. 
 High  power jamming (HiPwrJam) is a countermeasure available from AESAs due to their  natural broadband, beam agile, high gain, and high power attributes. AESAs also allow  long range air-to-surface data links (A-S Data Link) through the radar primarily for  map imagery. Because there may be thousands of wavelengths and a gain of millions  through a radar, automatic gain control and calibration (AGC/CAL) is usually required  fairly often. 
 .   (3.16) where l and a are in the same units, qa is the one-way half-power beamwidth, and n  is the number of hits per beamwidth. The approximation qa ≈ l/a is representative of  an antenna distribution yielding acceptable sidelobe levels. It can be seen that the antenna pattern pulse-to-pulse differential gain is  ∆ ∆ GdG ddG dTp22 2 ( )( ) ( )θθ θθθ θθ = =  (3.17) FIGURE 3.14  Antenna scanning effects: ( a) as seen by the antenna radiation pattern, due to the apparent  change in azimuth of the scatterer, θ θ θ2 1− =Tp; (b) as seen by the aperture illumination function, due  to the apparent motion, v x1=θ, of the scatterer relative to the antenna at position x; and ( c) step-scan  compensation of two received phasors ch03.indd   15 12/15/07   6:03:13 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 If we designate w as the width of the plate in the opposite plane, the area of the plate is A = €vv. To evaluate the maximum sidelobe levels of the plate RCS in the principal plane of measurement, we may replace the numerator of the sin (x)lx term in Eq. (11.17) by unity. 
  -ARITIME '##3 
 butwiththeconsequence thatthefrequency measurement isambiguous andresultsin blindspeeds,Eq.(4.8).Thepulsedoppler radar,ontheotherhand,hasahighpulserepetition frequency thatavoidsblindspeeds,butitexperiences ambiguities inrange.Itperforms doppler. 140 INTRODUCTION TO RADAR SYSTEMS  filtering on a single spectral line of the pulse spectrum. (A radar which employs multiple pulse  repetition frequencies to avoid blind speeds is usually classed as an MTI if its average prf  would cause blind speeds. 
 T. A. Croft and H. 
 GESTS THAT OWN SHIP HAS A SIGNIFICANT PROBLEM  PERHAPS WITH ITS RADAR  '.33 POSITION  OR MORE COMMONLY  A GYROCOMPASS OFFSET )F THERE IS GOOD POSITIONAL TIE 
 Thus a shorter phase shifter can be  had. which is especially advantageous at VHF or UHF frequencies. The reduction in length is  essentially equal to the wind-up factor of the helix, which is the ratio of the circumference to  the pitch. 
 R.. and I. Katz: Probing tlie Clear Atmosphere with High Power, High Resolution  Radars, Proc. 
 Tothis must beadded 12 lbforcables and brackets, 28lbforaninverter, and 25lbforaradome, sothat theinstalled weight ofthesetisabout 185 lb,well under athird that ofthe AN/APQ-13. Snap fasteners and spring-loaded bands are used asretaining elements tofacilitate the removal and replacement of units. Toachieve lowweight and simplicity, many attractive design features had tobesacrificed, including antenna stabilization, sector scan, ground- range sweeps, and long pulses formaximum range performance. 
 3783, May, 1978, Washington, D.C.  99. Weston, V. 
 Sherwin, “The spec - trum of X-band radiation backscattered from the sea surface,” J. Geophys. Res ., vol. 
 The remaining significant lag components are the acceleration and jerk lags. Electronically steerable arrays provide a means for inertialess angle track- ing. However, because of this capability the system can track multiple targets by rapidly switching from one to another rather than continuously tracking a single target. 
 Phase  detection occurs as in the conventional monopulse. Another single-channel system SCAMP  converts the sum and the two difference signals to different IF frequencies and amplifies them  simultaneously in a single, wide-band amplifier.20 The output is hard-limited to provide the  effect of an instantaneous AGC. The three signals after limiting are separated by narrowband  filters and then converted to the same IF frequency for further processing. 
  )NCREASING THE NUMBER OF DETECTIONS REQUIRED TO FORM  &)'52%  6ARIATION OF THE EXPECTED NUMBER  OF FALSE TRACKS WITH THE TRACK FORMATION  - 
 Oneoftheadvantages ofalensoverareflector antenna isIhe absenceofaperture blocking. Considerable equipme_nl canbeplacedatthefocusofthelens withoutinterfering withtheresultant antenna pattern.Thefirstmonopulse radarsusedlenses forthispurpose, butwithtimethemonopulse RFcircuitry wasreduced insizeandthe reflector antennacametobepreferred overthelens.Thelensiscapableofscanning thebeam overawideangle.Theoretically theLuneburg lensorthehomogeneous spherecancover 4nsteradians. Constrained metal-plate lensesarecapableofwidescananglesascompared to thelimitedscanning possible bymovingthefeedinaparaboloid reflector. 
 Geosci. Remote Sens. 1995 ,33, 1162–1169. 
 OF 
 Dawber and N. M. Harwood, “Comparison of doppler clutter cancellation techniques for  naval multi-function radars,” IEE Int. 
  
 Byproperly varying the relativepitispossible tosteerthedirection oftheradiation. Theradiating elements mightb~ipoles pen-ended waveguides, slotscutinwaveguide, oranyothertypeofantenna. Theinherent flexibility olTeredbythephased-array antenna insteering thebeambymeansof electronic control iswhathasmadeitofinterestforradar.Ithasbeenconsidered inthose radarapplications whereitisnecessary toshiftthebeamrapidlyfromoneposition inspace10 another, orwhereitisrequired toobtaininformation aboutmanytargetsataflexible,rapid datarate,Thefullpotential ofaphased-array antenna requires theuscofacomputer thatcan determine inrealtime,onthebasisoftheactualoperational situation, howbesttousethe capabilities olTeredbythearray. 
 It is oriented to be transparent to the  X-band focal-point feed behind it and reflective to the orthogonally polarized Ka-band  feed extending from the vertex of the paraboloid. Monopulse feed horns at different microwave frequencies can also be combined  with concentric feed horns. The multiband feed clusters will sacrifice efficiency but  can satisfy multiband requirements in a single antenna. 
 The improvement in receiver sensi­ tivity with an intermediate-frequency superheterodyne might be as much as 30 dB over the  simple receiver of Fig. 3.2.  Receiver bandwidth. 
 Mead, S. M. Sekelsky, and D. 
 The speed of movement of the point ofimpingement of the electron beam is far in excess of the capability ofdetection by the human eye. While the sweep must be repeated in accordance with the PRR, the actual rate of radial movement of the electron beam is governed by the size of theCRT screen and the distance represented by the radius of this screenaccording to the range scale being used. If the 20-mile range scale isselected, the electron beam must be deﬂected radially from the center of theCRT screen having a particular radius at a rate corresponding to the timerequired for radio-frequency energy to travel twice the distance of the rangescale or 40 nautical miles. 
 WAY APERTURE DISTRIBUTION IS MAPPED INTO THE FREQUENCY DOMAIN 4HE RESULTING POWER SPECTRUM DUE TO THE ANTENNA SCANNING IS  (F &FFA  ¤ ¦¥³ µ´aaL QQ L     WHERE Q   ANTENNA ROTATION RATE  A   HORIZONTAL ANTENNA APERTURE 4HIS SPECTRUM CAN BE APPROXIMATED BY A GAUSSIAN DISTRIBUTION WITH STANDARD DEVIATION  SQ QQ LCR AF NA   y       WHERE K  AND A ARE IN THE SAME UNITS   PA IS THE ONE 
 DEFINED  THE  EARLIER WORK DID DISCLOSE SOME GENERAL TRENDS  SUCH AS THE TENDENCY OF AVERAGE CLUTTER SIGNAL STRENGTHS AT LOW TO INTERMEDIATE GRAZING ANGLES TO INCREASE WITH THE #HAPTER . £x°Ó  2!$!2 (!.$"//+  GRAZING ANGLE AND THE WIND SPEED OR SEA STATE   AND GENERALLY TO BE GREATER FOR  VERTICAL POLARIZATION AND IN UPWINDDOWNWIND DIRECTIONS &OR OTHER REVIEWS OF SEA CLUTTER AND ITS HISTORY  SEE 3KOLNIK   .ATHANSON  AND ,ONG  3EA CLUTTER IS   HOWEVER  A COMPLEX PHENOMENON  PRESENTING VARIOUS FACES DEPENDING ON THE WAY THE RADAR VIEWS THE SCENE &OR EXAMPLE  IT IS COMMONLY NOTED THAT WHEN VIEWED ON AN ! SCOPE SIGNAL AMPLITUDE VERSUS RANGE   THE APPEARANCE OF SEA CLUTTER DEPENDS STRONGLY ON THE SIZE OF THE RESOLUTION CELL  OR  RADAR FOOTPRINT &OR LARGE CELLS  IT  APPEARS DISTRIBUTED IN RANGE AND MAY BE CHARACTERIZED BY A SURFACE 
 Each value of k  corresponds to a different set of N weights, and to a different doppler-filter response. The N  filters generated by the index k constitute the filter bank. Note that the weights of Eq. 
 TION IS K  "Y THE WAY  SUCH PHENOMENAL RESULTS HAVE BEEN APPROACHED IN THE FIELD  OF SEISMOLOGY "URST -ODE )F AVERAGE DATA RATE IS THE DRIVING CONSIDERATION  THEN THE INTEGRA 
   PP n  -AY   ( 2 7ARD  h$OPPLER PROCESSOR REJECTION OF AMBIGUOUS CLUTTER v  )%%% 4RANSACTIONS ON !EROSPACE  AND %LECTRONIC 3YSTEMS  VOL !%3 
 • Scan-to-scan processing can be used to remove stationary point clutter or moving-target indication (MTI) clutter residues. One can limit the number of false alarms with a fixed-threshold system by setting a very high threshold. Unfortunately, this would reduce target sensitivity in re- gions of low noise (clutter) return. 
 2ICE  AND THE 3PHERICAL  %ARTH +NIFE %DGE 3%+%  7HILE THESE EFFECTIVE 
 133. Sensors 2019 ,19, 2921 TM bwT 22 0Rh22 pRh (c) Top view of the ArcSAR geometric model  Figure 1. The geometric model of ArcSAR system. 
 Figure 15.5  displays measurements of vertically polarized sea clutter down to a grazing angle of  20° for wind speeds of about 15 kt from three independent experiments using airborne  radars at C-, X-, and K-band frequencies.31,34,35 Although there is no assurance that  FIGURE 15.4  General trends in clutter behavior for average  wind speeds (about 15 kt) based on NRL 4FR data. Plots represent  L-, C-, and X-band data within ±5 dB. ch15.indd   11 12/15/07   6:16:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 RECT DECISIONS ARE MADE RAPIDLY (OWEVER  IF THE RADAR TRACKS ARE CLOSE TO ONE ANOTHER  ERRORS ARE AVOIDED BY POSTPONING THE DECISION UNTIL SUFFICIENT  DATA ARE ACCUMULATED !N  INTERESTING EXAMPLE WITH RECORDED DATA IS SHOWN IN &IGURES  AND  &IGURE  SHOWS THE RADAR AZIMUTH  DETECTIONS OF THE CONTROL AIRCRAFT  THE RADAR DETECTIONS OF FOUR AIRCRAFT OF OPPORTUNITY IN THE VICINITY OF THE CONTROL AIRCRAFT  AND THE $& DETECTIONS ON THE RADAR ON THE CONTROL AIRCRAFT 4HE ASSOCIATION PROBABILITIES  WITH AND WITHOUT LIMIT 
 High  resolution along the transversal direction is achieved by forming a synthetic aperture.  This requires (i) to put the radar onboard a moving platform, e.g., an aircraft or a  satellite; (ii) to record the EM signals from each scatterer that is illuminated by the  moving antenna beam in successive instants of time, and (iii) to coherently combine  the signals—via a suitable azimuthal matched filter—thus focusing the sliding antenna  pattern in a narrower synthetic beam. Radiometric resolution, another key parameter,  is related to the capability of SAR of distinguishing different objects in the scene  on the basis of their EM reflectivity. 
 C. Mohr: Polarization Insensitive Phase Shirter for Use in Phased Array  Antennas. Microware J., vol. 
   30!#% 
 WRITE CAPABILITY  AND STABILITY 4HE DEVEL 
 TALLY CONTROLLED BY SWITCHES 4HE TOTAL DELAY PATH LENGTH THAT  HAS TO BE PROVIDED NON 
 11.3 Log-log version of the data displayed in Fig. 11.2. The echo characteristics of permeable (dielectric) bodies can be more compli- cated than those of perfect conductors because energy may enter the body and suffer several internal bounces before emerging. 
 The angle of arrival was  extracted by comparison of the amplitudes of the signals in the three-beam cluster. Beam  switching was performed separately from beam forming on both transmit and receive. This  example of a radar based on multiple-beam-forming is a system that is probably more complex  than would he needed now to accomplish the same radar mission. 
 TRACKING RADAR  9.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 separated and comparators provided for each polarization. The sum and difference  signals from the comparators are combined with 90° relative phase to obtain circular  polarization. Use of the previously described feeds for circular polarization would  require the waveguide circuitry to be prohibitively complex. 
 PLER FILTER VERY EFFECTIVELY 4HE DECISION THRESHOLD 4 FOR THE ITH CELL IS   4   !  3I 
 SCAN METHOD ARE THAT IT IS EASIER TO BUILD A STABLE TRANSMITTER  AND MUL 
 F., and T. B. A. 
 A. K. Fung and H. 
   PP n    " &RIEDLAND  h/PTIMUM STEADY STATE POSITION AND VELOCITY ESTIMATION USING NOISY SAMPLED POSI 
  
 Sensors 2019 ,19, 2921 Figure 24. Besides, it can be seen from the analysis results of the imaging quality in Table 3that the proposed imaging method could e ﬀectively improve the quality of ArcSAR image and achieve the high-precision imaging. T able 3. 
 B. Feldman: A Multiple· Unit Steerable Antenna for Short-Wave Receptil,n. /3cll  Sys. 
 S., 26  CADMIUM SCREENS, 61  Calcium tungstate, afterglow  of, 61  Calibrator (Cal), 40 et seq.  ‘Cat? station, 151  Cathode-follower, 96  Cathode-ray tube (CRT), 59-  71; ‘hard,’ 593 ‘soft,’ 595 electrodes, 60; screens,  60  Centimetric radar, 112 et seq.  Chain Home Low (CHL)  equipment, 48  urchill, Right Hon. 
 From Fig. 2.23 determine the correction factor for either cases 1 and 2 or cases 3 and 4 to be  applied to the signal-to-noise ratio found from step 1 above. The resultant signal-to-noise  ratio (S/ N)i is that which would apply if detection were based upon a single pulse. 
 at  2Ot) rimi. all targets below X ktn altitildc are beneath tlie radar line of siglit and normally  would riot be detected. Most commercial aircraft have a cross section greater than ihe 2 mZ  specified for this radar. 
 The receiver input can simply be  the mixer stage, especially in military radars that must operate in a noisy environment.  Although a receiver with a low-noise front-end will be more sensitive, the mixer input can  have greater dynamic range, less susceptibility to overload, and less vulnerability to electronic  interference.  The mixer and local oscillator (LO) convert the RF signal to an intermediate frequency  (IF). 
 6.29 and Eq. 6.30 gives the image components for frequency dependent gain and  phase errors. Similarly, substituting w ∆T for ∆ in Eq. 
 The matched filter frequency response for   a signal u(t) is   H f k U f ej f t mf( ) ( ) =∗ − 121π (8.42) where k1 is an arbitrary complex constant and U(  f  ) is the spectrum of u(t). The time  delay t1 is required to exceed the duration of u(t) to achieve a causal impulse response  that is zero for negative time. The matched filter impulse response is   h t k u t tmf( ) ( ) = −∗ 1 1 (8.43) The peak signal-to-noise to mean-noise-power ratio at the output of a filter with  frequency response H(  f  ) is defined as  ( )S NA o no=02 2σ (8.44) where Ao is the matched filter output signal amplitude at the peak of the signal and s  2 no  is the matched filter output noise power. 
 Initial progress was slow but a pre- production system was ﬁrst installed on a Sword ﬁsh in February 1943 [ 3]. The radar scanner was installed between the ﬁxed undercarriage struts of the Sword ﬁsh, providing a forward-looking sector scan. It was established in trials that the radar could reliably search for a small submarine with decks awash by sweeping a lane 14miles wide. 
 J.F.:TheContinuous-Cathode (Emitting.-Sole) Crossed-Field Amplifier, Proc.IEEE. vol.61.pr330J56,March,197J IX.Smith.W..andA.Wilczek: CFATubeEnables New-Generation Coherent Radar,Microwave i., \01.to.PI'.J942.74.April.197J. II}IIill.R.'1'.:Shiphoard RadarSystems. 
 Chaudhry and R. K. Moore, “Tower-based backscatter measurements of the sea,” IEEE   J. 
 After that when the radio wave transmits into the free space from the ionosphere down to the ground, the diffraction effect is simulated by the propagation simulator. It is calculated by solving the parabolic wave equation (PWE). Finally, the ionospheric transfer function (ITF) is obtained by incorporating the phase screen and propagation simulator. 
 Setting up the radars was very complex with many components requiring tuning on the ground to obtain a good match (e.g. the T/R cell, the anti-T/R cell, the mixer cavity, the klystron localoscillator coarse tuning, antenna VSWR etc). Before the incorporation of AGC, the operator also had to frequently adjust the local oscillator tuning, to compensate for thermal drift of the magnetron (transmitter) and klystron (local oscillator) frequen-cies. 
 This work relates to two parts of ionosphere detection. First, we evaluated the precision of TEC measured by the spaceborne synthetic aperture radar. Experiments showed impressive results whereby the precision was within 1 TECU when compared with the TEC obtained from ISR. 
 Abalanced mixersuppresses theevenharmonics of theLOsignal.AdOllhle-halallced mixerisbasically twosingle-ended mixersconnected in parallel and1ROOoutofphase.Itsuppresses evenharmonics ofboththeRFandtheLO signals.s.B Reactive imagetermination. Iftheimagefrequency ofamixerispresented withtheproper reactive termination (suchasanopenorashortcircuit), theconversion lossandthenoise figurecanbeJto2dBlessthanwitha"broadband" mixerinwhichtheimagefrequency is terminated inamatched load.6•IOThereactive termination causesenergyconverted tothe imagefrequency toberenected backintothemixerandreconverted toIF.16•24 Boththesumandtheimagefrequencies canbereflected backtothediodemixerto achievealowerconversion loss,butanumber ofadjustments arerequired forgoodresults.24 Onemethodforterminating theimageinareactive loadistoemployanarrowbandpass filter, orpreselect or,attheRFsignalfrequency. Alimitation ofthisapproach isthatitisnotsuitable forverywidebandwidths. 
 SCAN !N ! 
 Automatic detection and tracking equipments (also called plot extractors)  are commercially available for use with such radars for the purpose of collision avoi­ dance. Shore-based radar of moderately high resolution is also used for the surveillance of  harbors as an aid to navigation.  Space. 
 SPEED DEPENDENCE SHOWN BY THE PERCENTAGE OF WHITECAPS SEEN ON THE SURFACE   WHICH  AS NOTED IN 3ECTION   ARE TRACERS FOR BREAKING WAVES.   3%! #,544%2  £x°£Ç &)'52%   3EA SPIKES AT 8 BAND   GRAZING ANGLE  AND VARIOUS PULSE WIDTHS  A  SEA STATE  AND  B  SEA STATE  .OTE EQUAL AMPLITUDES AT THE TWO POLARIZATIONS AND A  D" DIFFERENCE IN CLUTTER STRENGTH  BETWEEN MODERATE AND WEAK WINDS FROM *0 (ANSEN AND 6 & #AVALERI  &)'52%   %XAMPLES OF CLUTTER PROBABILITY DISTRIBUTIONS  AT LOW GRAZING ANGLES AFTER $ 4RIZNA  . £x°£n  2!$!2 (!.$"//+  )N COMPARING STATISTICAL RESULTS  IT SHOULD BE KEPT IN MIND THAT TO THE EXTENT THAT  THE SEA SURFACE MAY BE VIEWED AS A STATIONARY HOMOGENEOUS PROCESS  AS IT GENERALLY  IS OVER THE DURATION AND SPATIAL EXTENT OF ANY PARTICULAR EXPERIMENTAL EVENT  THE SCAT 
 The  ambiguity diagram permits a visual indication of the ambiguities possible with a particular  waveform. The ambiguity problem is characteristic of a single target, as is the detection and  accuracy requirements of a waveform, whereas resolution is concerned with multiple targets.  The ambiguity diagram may be used to determine the ability of a waveform to reject  clutter by superimposing on the TR ,fd plane the regions where clutter is found. 
 Geosci. Remote Sens. 2004 ,42, 2039–2045. 
 Often it happened that more than 10 y ears would pass from the  definitions phase until the deployment -ready apparatus would be realized.  Only after the 70’s did  Radar technology experience comparably rapid phase of development through the opening of  new fields of usage, as in the fields of se nsors and remote sensing.  . 
 Beam Switching . With properly designed lenses or reflectors, a number of inde - pendent beams may be formed by feeds at the focal surface. Each beam has substan - tially the gain and beamwidth of the whole antenna. 
 Height measurement precision is deter - mined by the radar altimeter’s post-processing range resolution and by the amount  of averaging available for each estimate. Note that a precision measurement may still  have poor accuracy, if its mean value is biased away from the correct value. When  comparing two neighboring height measurements, any constant bias is cancelled by  subtraction as long as the error is the same for both measurements. 
 Fading of the HF signals can occur due to the rotation of the plane of polarization over the  ionized region of the propagation path. Multipath interference from more than one refracting  region, as well as dynamic irregularities in the ionospheric propagation path, are two other  sources of fading.  The specific region on the earth's surface illuminated by an HF radar depends on iono­ spheric conditions. 
 [ CrossRef ] ©2019 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http: //creativecommons.org /licenses/by/4.0/). 
 However, such sources may have greater power and antenna gain at their  disposal, allowing the signals to reach the radar receiver with appreciable strength,  sometimes after propagation via highly disturbed and nonstationary ionospheric paths  (as commonly occurs in the equatorial and polar regions). Under normal circumstances,  OTH radars seek to find relatively clear frequency channels in the user-congested HF  spectrum, so the presence of interference from other manmade sources is effectively  diminished by suitable frequency selection. When jamming is present, the radar may  need to operate with much higher than usual levels of interference that can degrade  performance. 
 Therequired transmitter power,thelossinantenna gain.changeof beamwidth, complexity ofcomputer control, traffichandling, polarization change,andtotal systemcostmustallbeconsidered whenevaluating therelativemeritsofsuchtJntennas fora particular application. Conformal arrays.130 135Oneofthedesiresoftheradarsystems engineer istobeableto placearrayelements anywhere onanarbitrary surfaceandachieveadirective beam,withgood sidelobes andefficiency, whichcanbeconveniently scanned electronically. Anarrayofradiat­ ingelements arranged alongthenoseofanaircraft,onthewing,orthefuselage wouldthusbe anattractive optionforthesystems designer. 
 STATE TRANSMITTER  AND INTERFAC 
 (ILL    ! &ARINA AND &  ! 3TUDER  h! REVIEW OF #&!2 DETECTION TECHNIQUES IN RADAR SYSTEMS v  -ICROWAVE *OURNAL  PP n  3EPTEMBER   % #ONTE AND ! $E -AIO  h-ITIGATION TECHNIQUES FOR NON 
 DiCurcio, “AN/TPQ-27 precision tracking radar,” in IEEE Int. Radar Conf. Rec ., Arlington,  V A, 1980, pp. 
 Sensors 2018 ,18, 3750 Two ISAR images used in the InISAR imaging are usually highly correlated, so they are more obvious in joint sparsity. Based on such prior information, the following joint sparse metric functions with global sparsity can be obtained as: /bardblg/bardblp,0=/bardbl/parenleftbig|g1|p+|g2|p/parenrightbig1/p/bardbl0,p≥1, (16) where,/bardbl•/bardbl0is zero norm, which represents the number of non-zero elements in the vector. Different p values correspond with different mixed norm forms. 
 99. K. Rogers, “Engineers unlock mystery of car-door device failures,” Las Vegas Review Journal ,  August 19, 2004, p. 
 65. von Schlachta, K.: A Contribution to Radar Target Classification, International Coriference  RADAR-77, Oct. 25-28, 1977, pp. 
 Stark, L.: A Helical Line Scanner ror Beam Steering a Linear Array, I RE Trans., vol. AP-5.  pp. 
 ● On-board, real-time processing is a possibility. ● More sophisticated (expensive) hardware is required: two antennas, two receiver  channels, and two sets of analog-to-digital (A/D) converters. ● Example results are given by Adams et al.,20 who include an InSAR image of  the stadium at the University of Michigan in Ann Arbor, viewable with two-   color glasses. 
 Thelargerthedielectric constant (orindexofrefraction) ofasoliddielectric lens,the thinneritwinbe.However, thelargerthedielectric constant, thegreaterwillbethemismatch between thelensandfreespaceandthegreaterthelossinenergyduetoreflections atthe surfaceofthelens.Compromise valuesoftheindexofrefraction liebetween 1.5and1.6.Lens reflections mayalsobereduced withtransition surfaces asinoptics.Thesesurfaces shouldbea quarter wavethickandhaveadielectric constant whichisthesquarerootofthedielectric constant ofthelensmaterial. Artificial dielectrics.4547Insteadofusingordinary dielectric materials forlensantennas, itis possible toconstruct themofartificial dielectrics. Theordinary dielectric consistsofmolecular particles ofmicroscopic size,buttheartificial dielectric consistsofdiscrete metallicordielec­ tricparticles ofmacroscopic size.Theparticles maybespheres, disks,strips,orrodsimbedded inamaterial oflowdielectric constant suchaspolystyrene foam.Theparticles arearranged in someparticular configuration inathree-dimensional lattice.Thedimension oftheparticles in thedirection paralleltotheelectric fieldaswellasthespacing between particles shouldbe smallcompared withawavelength. 
 I Introduction  8.2 Basic l 'onccp!s  8 . .1 Phase Shifters  8.4 I· rcq ucncy-Sca n Arrays  8.5 A rrny Elements  8.6 Feeds for Arrays  8.7 Simultaneous Multiple Beams from Array Antennas  8.8 R...indom Errors in Arrays  8.9 Computer Control of Phased-Array Radar  8.10 Other Array Topics  8.11 Applications of the Array in Radar  8.12 Advantages and Limitations  References  9 Receivers, Displays, and Duplexers  9.1 The Radar Receiver  9.2 Noise Figure  ~.3 Mixers  9.4 Low-Noise Front-Ends  9.5 Displays  9.6 Duplexers and Receiver Protectors  References  10 Detection or Radar Signals in Noise  10. l Introduction  I0.2 Matched-Filler Receiver  10.3 Correlation Detection  10.4 Detection Criteria  10.5 Detector Characteristics  10.6 Performance of the Radar Operator  10.7 Automatic Detection  I0.8 Constant-False-Alarm-Rate (CFAR) Receiver  References  11 Extraction of Information and Waveform  Design  I I.I Introduction  J 1.2 Information Available from a Radar  J J .3 Theoretical Accuracy of Radar Measurements  11.4 Ambiguity Diagram CONTENTS vii  254  258  262  264  270  273  278  278  279  286  298  305  306  310  318  322  328  334  335  337  343  343  344  347  351  353  359  366  369  369  369  375  376  382  386  388  392  395  399  399  399  400  411 . 
 FICULT TO FIND AT MANY RADAR SITES  AND INTERRUPTION OF ROTATION OF THE ANTENNA TO CON 
 Inthe case ofclouds moving at 30mph, that gives usVI=900 mph, which isasuitable value asfaras Fig. 16.24 isconcerned. Since v,=Xj,/89, itcanbeseen that such ahigh value ofVIisobtainable, when anormal PRF isused, only bygoing toa wavelength oftheorder of100cm. 
 It represents the transition from closed  loop to open loop operation. One of the functions of the servo system is to reduce the . TRACKING RADAR 179  fluctuations of the input signal by filtering or smoothing. 
 The 0s and 1s are summed in a  moving window. This detector incurs a CFAR loss of about 2 dB but achieves a fixed  Pfa for any unknown noise density as long as the time samples are independent. This  detector was incorporated into the ARTS-3A postprocessor used in conjunction with the  Federal Aviation Administration airport surveillance radar (ASR). 
 18.21. The peaking is an indication of system instability but is allowed to be as high as tolerable, typ- ically up to about 3 dB above unity gain to obtain maximum bandwidth for a given servomotor drive system. System A of Fig. 
 This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http: //creativecommons.org /licenses/by/4.0/). 248. sensors Article Aspect Entropy Extraction Using Circular SAR Data and Scattering Anisotropy Analysis Fei T eng1,2,3, Wen Hong1,2and Yun Lin4,* 1Key Laboratory of Technology in Geospatial Information Processing and Application System, Chinese Academy of Sciences, Beijing 100190, China; scutengfei@163.com (F.T.); whong@mail.ie.ac.cn (W.H.) 2Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China 3School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 101408, China 4School of Electronic Information Engineering, North China University of Technology, Beijing 100144, China *Correspondence: ylin@ncut.edu.cn; Tel.: + 86-135-8154-3995 Received: 27 November 2018; Accepted: 15 January 2019; Published: 16 January 2019/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: In conventional synthetic aperture radar (SAR) working modes, targets are assumed isotropic because the viewing angle is small. 
 Or, if the relative velocity were known, the receiver could be pretuned to the correct received frequency, negating the need to search the frequency band over which the doppler shift might occur. The usual radar provides the location of a target in range and angle. The rate of change of target location can also be measured from the change in range and angle with time, from which the track can be established. 
 Tliis sweep sliows several fixed targets and two moving targets indicated by the two  arrows. On the basis of a single sweep, rnoving targets cannot be distinguislied from fixed  targets. (It may be possible to distinguish extended ground targets from point targets by the  strctcl~irig of the echo pulse. 
 TION )F BOTH ACCUMULATORS ARE CLOCKED AT THE SAME RATE  THE CHIRP SLOPE IS GIVEN BY   $ $F T-F3 .FOUTCLK      WHERE  -3   CHIRP SLOPE WORD  INPUT TO THE FREQUENCY ACCUMULATOR  .F   NUMBER OF BITS OF FREQUENCY ACCUMULATOR &REQUENCY MODULATED AND PHASE MODULATED WAVEFORMS CAN BE CREATED APPLYING TIME 
 vol. 46. pp. 
 PATH ANALYSIS AND TO AID IN RADAR 
 FREQUENCY RADAR  ESTIMATION OF CLOUD AND PRECIPITATION PROPERTIES USING AN ARTIFICIAL NEURAL NETWORK v IN  TH )NT  #ONF ON 2ADAR -ETEOROL  -UNICH  !-3  PP n    $ !TLAS  h!DVANCES IN RADAR METEOROLOGY v IN  !DVANCES IN 'EOPHYSICS  6OL   .EW 9ORK  !CADEMIC 0RESS    2 'UNN AND ' $ +INZER  h4HE TERMINAL VELOCITY OF FALL FOR WATER DROPLETS IN STAGNANT !IR v   * -ETEOROL  VOL   PP n     * 3 -ARSHALL AND 7 - + 0ALMER  h4HE DISTRIBUTION OF RAINDROPS WITH SIZE v  * -ETEOROL  VOL     PP n     $ # "LANCHARD  h2AINDROP SIZE DISTRIBUTION IN (AWAIIAN RAINS v  *  -ETEOROL  VOL     PP n    $ - ! *ONES  h CM AND  CM WAVELENGTH RADIATION BACKSCATTER FROM RAIN v IN  TH 7EATHER  2ADAR #ONF  !-3  "OSTON    PP n  + , 3 'UNN AND * 3 -ARSHALL  h4HE DISTRIBUTION WITH SIZE OF AGGREGATE SNOWFLAKES v   * -ETEOROL  VOL   PP n    * 7 7ILSON AND % ! "RANDES  h2ADAR MEASUREMENT OF RAINFALLA SUMMARY v  "ULL !M  -ETEOROL 3OC  VOL   PP n     ) :AWADZKI  h/N RADAR 
 ORBIT PLANE CONFIGURATIONS 2ADAR DATA ARE RECORDED IN A  'BIT SOLID 
 SIGHT ,/3  FROM THE RADAR TO THE TARGET REGION AND  CROSSRANGE  RESOLUTION TO MEAN THE RESOLUTION ALONG THE DIRECTION PERPENDICULAR TO THE ,/3 AND PARALLEL TO THE GROUND 4HE FORMER IS ALSO FREQUENTLY TERMED  DOWNRANGE RESOLUTION  TO  EMPHASIZE THAT IT IS ALONG THE ,/3 #ROSSRANGE RESOLUTION IS ALSO FREQUENTLY CALLED  AZI 
 Contaminants.  The idea of pouring oil on troubled waters is a familiar one: the  angry surface will smooth and subside. In another age, the survival-gear locker of  every sailing ship would contain a bottle of oil to quiet the sea in a storm. 
 PULSE -4) AND CASCADED  . 
 England), no.40. pr.475H.October. 1t>57. 
 24. Temme, D. H.: Diode and Ferrite Phaser Technology, " Phased Array Antennas," A. 
 7.3. To the left ofthe box marked “Rectangular topolar coordinate resolv w,” thedevice isidentical with the dead-reckoning computer just described. Since thebasic coordinates ofthePPI arerange and azimuth, itisneces- sary toconvert the cartesian position information topolar coordinates; this isdone inthe resolver shown. 
 Tllc reduced respotlse outsidz tlic  design band reduces the effects of out-of-band interference and can rcducl: the nose-on riid:t~.  cross section of the aircraft at frequencies other than tliat for wliicl~ the antenna is designed.  In conventional application, the radome is fixed and the antenna is scanned. 
 PULSE DOPPLER FILTER BANK  AND FOR NONMOVING hZERO 
 An 80% probability of detection and a probability of false  alarm of 10–4 is specified by IMO, as shown in Table 22.1.2 Taking into account all performance requirements, typical compliant systems for  commercial vessels have peak transmit powers of 4 – 60 kW, the lower powers being  confined to 9 GHz systems. Antenna gains from 28 to 33 dB are typical, with associ - ated horizontal beamwidths ranging from about 2.5° to less than 1°. Pulse lengths are  switchable, generally in the range from 50 ns to 1 µs, with PRFs ranging from 350 to  3,000 Hz or more. 
 The cross-range resolution of a synthetic aperture radar (SAR) for imaging a scene such as terrain can be explained as being due to resolution in doppler, although a SAR is usually thought of as generating a large "synthetic" antenna by storing received signals in a memory. The two views—doppler resolution and synthetic antenna—are equivalent. Resolution in the doppler domain is a natural way to envision the cross-range resolution achieved by the inverse synthetic aperture radar (ISAR) used for the imaging of a target. 
 CHANNEL VARIATION L )MPROVED LINEARITY L &LEXIBILITY OF BANDWIDTH AND SAMPLE RATE L 4IGHT FILTER TOLERANCE  PHASE LINEARITY  AND IMPROVED ANTI 
 Ji, Y.F.; Zhang, Q.L.; Zhang, Y.S.; Dong, Z. L-band geosynchronous SAR imaging degradations imposed by ionospheric irregularities. China Sci. 
 6.56  Near-Field Ranges  .............................................  6.57  Miscellaneous Test s  ..........................................  6.59  7. 
 Ward, “RAMP’s new primary surveillance radar,” Microwave Journal , p. 105,  December 1984. 36. 
 ZERO .%R     DEFINED AS THE  LEVEL OF R   THAT PRODUCES A RECEIVED POWER EQUAL TO THE THERMAL NOISE POWER  IE  AN  3.2 OF UNITY 7E SET 3.2    AND HAVE   .%2K 4& 6 0'RSPY LD         C O S,OSS 4X 
 The Phanfasb-on.-The phantastron ofFig. 13~17isaflip-flop ofa quite different type which serves asatiming circuit maintaining its calibration toabout one per cent. Inthe normal condition, V1is quiescent, with the cathode sufficiently positive tocut offthe second control grid sothat allofthe current goes tothe screen. 
 Thefilteredsideband servesthefunction ofthelocal oscillator. Whenanechosignalispresent, theoutputofthereceiver mixerisanIFsignalof frequency.r.F+Ib'whereII>iscomposed oftherangefrequencY!r andthedoppler velocity frequency Jd'TheIFsignalisamplified andappliedtothebalanced detector alongwiththe local-oscillator signal.IiI"Theoutputofthedetector contains thebeatfrequency (range frequency andthedoppler velocity frequency), whichisamplified toalevelwhereitcan actuatethefrequency-measuring circuits. InFig.3.13,theoutputofthelow-frequency amplifier isdividedintotwochannels: one feedsanaverage-frequency counter todetermine range,theotherfeedsaswitched frequency counter t6determine thedoppler velocity (assuming fr>fd)'Onlytheaveraging frequency counter needbeusedinanaltimeter application, sincetherateofchangeofaltitudeisusually small. 
 (It is not always true that two radars cost  more, are more complex, or occupy more volume than a "single" radar designed to do the  same job.) Another advantage of the separate nodding-beam height finder in military applica­ tions is that it generally operates at a higher frequency (S or C bands are common choices)  than does the 20 air-surveillance radar. This increases the ECCM capability of the system  since a jammer must radiate in both radar bands simultaneously to deny the location of air­ craft targets. The use of a higher frequency for the height finder is appropriate since it can be of  shorter range than the 20 air-surveillance radar, and the antenna aperture can be of smalkr  size for a given beamwidth. 
 CIES  AND !'# SETTINGS BECAUSE OF THE NONLINEAR CHARACTERISTICS OF MOST 2& FRONT ENDS !LSO FOR MODES LIKE 4&4!  A FULL SET OF OFF 
 The PPI ofFig. 12.2 isoftheso-called “rotating coil” type. Asingle deflection coil driven bythe range-sweep amplifier produces aradial range sweep. 
 They can be plotted on the bistatic plane when RT and RR are converted to polar coordinates (r,6), as shown on Fig. 25.1: RT2RR2 = (r2 + L2M)2 - ^L2 cos2 6 (25.5) where L is the baseline range. Figure 25.2 is such a plot for k arbitrarily set to 3OL4. 
 Jordan, “The Seasat-A synthetic-aperture radar system,” IEEE Journal of Oceanic  Engineering , vol. OE-5, pp. 154–164, 1980. 
 Thetraveling-wave-tube amplifier hasalso beenconsidered asalow-noise front-end, butithasbeenovertaken byotherdevices. Cryo­ genicparametric amplifiers andmasersproduce thelowestnoisefigures, buttheadded complexity ofoperating atlowtemperatures hastempered theiruseinradar. Thenoisefigureoftheordinary" broadband" mixerwhoseimagefrequency ister­ minated inamatched loadisnotshowninFig.9.4.Itwouldlieabout2dBhigherthanthe noisefigureshownfortheimage-recovery mixer. 
 THE 
 Skolnik, Radar Applications , New York: IEEE Press, 1988.  9. R. 
 ON SATELLITE FOR SINGLE 
 31. Blake, L. V.: Ray Height Computation for a Continuous Nonlinear Atmospheric Refractive-Index Profile, Radio Sd., vol. 
 SECTION OF THE SEA SURFACE  "ACKGROUND MODEL v  * 'EOPHYS 2ES  VOL     NO #       6 +UDRYAVTSEV  $ (AUSER  ' #AUDAL  AND " #HAPRON  h! SEMIEMPIRICAL MODEL OF THE NORMAL 
 The flow was confined by completely encapsulating the  garnet in a teflon jacket. Thus the cooling liquid was in direct contact with the garnet for  efficient transfer of dissipated heat. Some of the highest power phase shifters have been  obtained with this design. 
 Theenvelope oftheRFleakage mightbesimilartothatshowninFig.9.8.The short-duration, large-amplitude" spike~'attheleadingedgeoftheleakagepulseistheresultof thefinitetimerequired fortheTRtoionizeorbreakdown.Typically, thistimeisoftheorder oftonanoseconds. AfterthegasintheTRtubeisionized,thepowerleakingthrough thetube isconsiderably reduced fromthepeakvalueofthespike.Thisportionoftheleakagepulseis termedtheflat.Damage tothereceiverfront-end mayresultwheneithertheenergycontained withinthespikeorthepowerinthefiatportionofthepulseistoolarge...Typical" TRtubes mighthaveaspikeleakageofoneergorlessandmightprovideanattenuation oftheincident transmitter poweroftheorderof70to90dB.. lime --+ Figure 9.8 Leakage pulse through a I'R tube. 
 I·  0  0 001  140  120  ID 100 "CJ  I  £ u 80 .!:!  c  Cl)  E 60 Cl)  > 0 a E  40  20  0  0 001 0.01  Clutter ~,rectrol width I radar prf  (a) MTI AND PULSE DOPPLER RADAR 125  I -·  5  4,6  · --ave.  3, 7  2,8  0.1  --·--- ----t---+--l·--l-1--1---+-l  001  Cluller spectral width /radar prf  (h) 0 l 5  ove,  4, 6  3 , 7  2,8  Figure 4.26 Improvement factor for a 3-pulse (double-canceler) MTI cascaded with an 8-pulse doppler  filter hank. or integrator. 
 2. The combiner should have RF isolation among ports, such that failed mod- ules do not affect the load impedances or combining efficiency for the remaining functioning modules. 3. 
 AES-12, pp. 793-798, November, 1976.  83. 
 The relative amplitude of the two scatterers is assumed to be a, and the relative  phase difference is a. Differences in phase might be due to differences in range or to rclkcting  properties. The ratio a is defined as a number less than unity. 
 1964. 41.Motkin.D.L.:Three-dimensionai AirSurveillance Radar.Systems Technology, no.21,pp.29-33. June,1975.(Plessey Co.,liford,England.) 42.Watanabe. 
 DELAY IMBALANCES CAN  BE CORRECTED BY ADDING TIME DELAY TO THE !$ SAMPLE CLOCK  AS SHOWN IN &IGURE  ,ARGE TIME 
 Wallis, “The mean echo and echo  cross-product from a beamforming interferometric altimeter and their application to ele - vation measurements,” IEEE Transactions on Geoscience and Remote Sensing , vol. 42,   pp. 2305–2323, 2004. 
 Wilson and H. P. Roesli, “Use of doppler radar and radar networks in mesoscale analysis and  forecasting,” ESA J ., vol. 
 Pothecary, J. F. Sevic, and  N. 
 MDPI   St. Alban-Anlage 66   4052 Basel  Switzerland Tel: +41 61 683 77 34  Fax: +41 61 302 89 18 www.mdpi.com ISBN 978-3-03936-122-9 . 
 The height diﬀerence threshold is determined by the system parameters given in Table 1. Therefore, the change of system parameters has an impact on height di ﬀerence threshold: under the premise of changing only single system parameter, the increase of θbw,θand Rspwill cause the height di ﬀerence threshold to rise, while the increase of the fc,rwill cause the height di ﬀerence threshold to decrease. 4. 
 The marker can beused todetermine thedesired delay inadvance bysetting itatthe point ofinterest. Since the minimum range ofthemarker isincreased bythefixed delay, aswitch (S2) ispro- vided forsubstituting theearlier pulse when anundelayed sweep isbeing used atshort ranges. The dial calibration must then bechanged accord- ingly, thesimplest method being theuse ofasecond scale. 
 Hogg, D. C., and W.W. Mumford: The Effective Noise Temperature of the Sky, Microwave J, vol. 
 E. Collin and F. J. 
 Chapters 9through 14take upthe leading design con- siderations forthevarious important components that make uparadar set. These chapters aresothorough intheir treatment that Chap. 15, which gives two fairly detailed examples ofactual system design, can be quite brief. 
 MeteoroL Soc., vol. 60, pp. 1048-1058, 1979. 
 These quantities vary somewhat with disk speed, sothat itisnoteasy todesign arotary spark-gap pulser forvariable pulse rate. ‘I’he Recharging Circuit.—In allforms ofnetwork pulsers itisnecessary torecharge thenetwork between pulses. This should notbedone attoo rapid arate. 
 J. S. Ajioka, “Frequency-scan antennas,” Antenna Engineering Handbook , Chap. 
 Radar System Engineering  Chapter 12 – Selected Radar Applications  141     13.3 Automotive Radar (ACC)   13.3.1  History   The first ideas to use Radar devices in vehicles date back to the 1950’s.  Radar devices are  generally attractive for vehicles, since they are able to determine the distance and velocity of  other objects, regardless of weather.  General Motors realized the first integrati on in 1959 in  the Cadillac Cyclone [GM], Figure 13.9. 
 A. Williams, Jr., E. M. 
 I.eicliter, M.: Reatii i'oiriting Errors of Long Line Sources, H~tglres Aircrqji C'o. Teclr. Afe~tr. 
 PORTIONAL TO THE RECIPROCAL OF THE BANDWIDTH  WIDER 
 It is plotted in Fig. 2.2d.  , ?'lie starid:trd dcviatiori of the Kayleigli density of Eq. 
 T. Wu: "The Scattering and Diffraction of Waves," Harvard University Press.  Cambridge. 
 MAGNITUDE SPAN OF RANGES IS VERY LIKELY DUE TO A RISE IN THE LOCAL GRAZING ANGLE PRODUCED BY REFRACTION IN THE EVAPORATIVE LAYER FIRST  METERS OR SO ABOVE THE SURFACE   3UCH EFFECTS SHOULD BE SUSPECTED WHENEVER THE RADAR PROPAGATION PATH  EXTENDS BEYOND THE OPTICAL HORIZON 3HADOWING 4HE POSSIBILITY OF SHADOWING MUST BE CONSIDERED SERIOUSLY WHENEVER  THE SEA IS VIEWED AT GRAZING ANGLES SMALLER THAN THE RMS SLOPE ANGLE OF THE SEA SURFACE 3OME EXAMPLES WERE DISCUSSED EARLIER IN CONNECTION WITH THE BEHAVIOR OF SEA CLUTTER AT LOW GRAZING ANGLES IN &IGURE  )N FACT  THE SHARP FALLOFF OF THE  NONDUCTING DATA IN  &IGURE  MIGHT BE FURTHER EVIDENCE OF THE  THRESHOLD SHADOWING  MENTIONED EARLIER  (OWEVER  THE COMMON IDEA OF SHADOWING DERIVES FROM THE GEOMETRICAL OPTICS CONCEPT OF A SHARP TRANSITION BETWEEN LIGHT AND DARKNESS "Y CONSIDERING THE IMPLICATIONS OF DIFFRACTION AT THE WAVE PEAKS  IT IS  POSSIBLE TO DETERMINE THE DOMAIN OF RADAR FREQUEN 
 IO,  pp. 38-45, May, 1973.  50. 
 Rejection  of sidelobe returns of discrete  ground targets needed. High PRF Pulse Doppler range ambiguous doppler unambiguousAllows thermal noise-limited  detection of targets with high radial  velocities. Single doppler blind  zone at zero velocity. 
 The result is the desired pulse radar form of the range equation: IP/rGfiptfFfF*}™D = _£ i L i L_ n 1 (Yl R™ [ (4^kT1D0C8L \ (2'10) *In some of the literature it is stated that the matched-filter output signal-to-noise ratio is 2EJN0. That statement is based on defining peak signal power as the instantaneous value occurring not only at the peak of the output-pulse waveform but also at the peak of an RF cycle, where the instantaneous power is theoretically twice the average power. North's definition, based on the signal power averaged over an RF cycle, is consistent with the definition of noise power as the average over both the RF cycles and the random noise fluctuations. 
 Dee, and Dr Skinner were largely respon- sible for H2S, and Denis Robinson made his contribu-  tion to a system of H2S ‘television’ for locating ships at sea. Gee, the long-range navigational system which made mass raids possible, and which is now a most reliable system of radar navigation on civil air lines, was deve- loped by R. J. 
 SURFACE INDEX OF  REFRACTION USING RADAR PHASE MEASUREMENTS FROM GROUND TARGETS v  * !TMOS /CEAN 4ECH  VOL    PP n    0 ( (ILDEBRAND AND 2 + -OORE  h-ETEOROLOGICAL RADAR OBSERVATIONS FROM MOBILE PLATFORMS v  #HAPTER  IN 2ADAR IN -ETEOROLOGY  !TLAS ED   "OSTON !-3    PP n   2 * 3ERAFIN AND 2 3TRAUCH  h-ETEOROLOGICAL RADAR SIGNAL PROCESSING   IN @AIR QUALITY METEOROLOGY AND  ATMOSPHERIC OZONE v !MERICAN 3OCIETY FOR 4ESTING AND -ATERIALS  PP n  0HILADELPHIA    , * "ATTAN   2ADAR /BSERVATION OF THE !TMOSPHERE  #HICAGO 5NIVERSITY OF #HICAGO 0RESS    $ !TLAS ED   2ADAR IN -ETEOROLOGY  "OSTON !-3    " 2 "EAN  % * $UTTON  AND " $ 7ARNER  h7EATHER EFFECT S ON RADAR v IN  2ADAR (ANDBOOK  ST  %D  - 3KOLNIK ED   .EW 9ORK -C'RAW 
 Note that if the multiple transmitting beams are contiguous and at  the same frequency, the composite transmitted pattern is similar to the pattern from a single  beam encompassing the same angular region.  The receiving beam-forming network may be at IF or RF. Tapped delay lines have been a . 
 Layers have been observed from altitudes of  ahout 0.3 to more than 22 km. with the greatest number appearing in the vicinity of 1 to  2 km.107·109 A typical layer associated with a subsidence inversion might exhibit a decrease of  about 20N units in a thickness of30 to 50 m110 [where N = (n -1)106, n = refractive index].  The echoes from clear-air turbulence are quite weak and are seen only by high-power  radar. 
  IS A MOBILETRANSPORTABLE SERIES OF SOLID 
 Frolind, “Precision processing of CARABAS HF/VHF-band SAR  data,” Proceedings IEEE Geoscience Remote Sensing Symposium  IGARSS 1999 , Hamburg,  Germany, vol. 1, 1999, p. 47–49. 
 The effect of the time-varying sea roughness on the signal phase and wavefront  structure, manifested in the time delay, doppler spectrum, and direction-of-arrival  spectrum of the received signal, can be computed using the multiple scattering theory  of Anderson et al.161 FIGURE 20.40  Curves of propagation loss versus range, as used for esti - mating surface wave radar performance. The surface is assumed to be smooth,  target and antenna heights are 2 m, conductivity is taken as 5 S/m, and the  dielectric constant is 80. ch20.indd   73 12/20/07   1:17:14 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Automatic Noise-level Control. AGC is widely employed to maintain a desired level of receiver noise at the A/D converter. As will be described in Sec. 
 (Reprinted in ref. 18.)  29. Dunn, J. 
 SYNCHRONOUS ALTIMETERS  THE LARGEST SOLAR  CONSTITUENT TWICE DAILY  ALIASES TO ZERO  AND ALL TIDAL CONSTITUENTS THAT ARE PRIMARILY DEPENDENT ON SOLAR FORCES ALIAS TO FREQUENCIES CLOSE TO ZERO 4HEORETICAL &OUNDATIONS  4HE FOLLOWING PARAGRAPHS PROVIDE A SUMMARY OF THE  KEY CHARACTERISTICS OF A SPACE 
 Figure 13.32 shows a number of parallel-feed systems. They  frequently combine a number of radiators into subarrays, and the subarrays are then  combined in series or in parallel to form sum and difference patterns. Figure 13.32 a shows a matched corporate feed , which is assembled from matched  hybrids. 
 The mean square va1ue (m2) of the current  when multiplied by the resistancet gives the mean power. The mean square value of voltage  times the conductance is also the mean power. The variance is defined as  The variance is the mean square deviation of x about its mean and is sometimes called the  second central moment. 
 SIGNAL POWER LEVELS )TS INSERTION LOSS MAY  BE HIGH BECAUSE IT IS FOLLOWED BY AMPLIFICATION ON TRANSMIT AND PRECEDED BY AMPLI 
 FIG. 14.5 IF circuitry for a Marsh and Wiltshire bridge (shown in Fig. 14.4). 
 RAD PHASE RUN 
 CHAPTER 3 PROPERTIES OF RADAR TARGETS SIMPLE TARGETS BY A.J.F.SIEGERII, L.N.RIDENOUR, AND M.H.JOHNSON1 3.1, Cross Section inTerms ofField Quantities. -In the preceding chapter the quantity “cross section ofatarget” was introduced phe- nomenologically. Theoretical considerations which incertain cases will allow theprediction ofthevalue ofthese quantities from theknown properties (shape, material) ofthetarget will bepresented inthis chapter. 
 When the display is connected  directly to the video output of the receiver, the information displayed is called raw video. This  is the "traditional_" type of radar presentation. When the receiver video output is first  processed by an automatic detector or automatic detection and tracking processor (ADT), the  output displayed is sometimes called synthetic video. 
 For  this purpose you must imagine a variable resistance in  series with the condenser. We are measuring the voltage  across the condenser only, of course, and not across the  resistance. At the moment that the condenser is first  connected we turn the resistance up to maximum,  decreasing it as the condenser becomes gradually  charged. 
 FREQUENCY AMPLITUDE NOISE  IS   SQBS" SSK!F     . 
 §S PULSE IS COMPRESSED TO  §S SUCH THAT HIGH DUTY CYCLE IS ACHIEVED WITHOUT COMPROMISING RANGE RESOLUTION 4HE TRANSMITTER CONSISTS OF  MODULES  EACH CAPABLE OF  7 POWER OUT 
 HF OVER-THE-HORIZON RADAR  20.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 The traces plot the virtual height versus radiowave frequency for the ordinary  ray (see  subsection below on radiowave propagation). Soundings of this type—ionograms— measure the return trip time delay for a signal to travel up to the height at which the  electron density is sufficient to reflect it, that is, where the plasma frequency fp equals  the incident radiowave frequency. Also shown in Figure 20.5 is the corresponding monthly median, taken from the  model of Thomason et al.22 Consider the critical frequency, that is, the highest reflected  frequency, corresponding to the ionosphere’s peak electron density. 
 Ifthe order isimmaterial, the rate ofrandom interroga- tion will betwice asgreat, namely, ATNIN2. Inmaking acomparison between thetwo systems, itisnecessary to keep inmind that one must use estimates ofthe numbers ofrandom pulses that will bepresent after thesystem hasbeen introduced. Chang- ing radar sets togive double pulses increases the number atthe radar frequency; adding coincident interrogating pulses atasecond frequency increases thenumber atthat frequency. 
 from Weinsto~k,'~~ is an example of the timing of events that must occur in  radar trans~nission and reception. The bottom figure shows the timing of the radar transmis-  sions. While the radar is still receiving echoes from the (N - 1)st dwell, a block of command  words is conirnunicated to the radar for control of the Nth dwell and the beam-steering  cornputer calculates the phase-shifter orders needed.for the next transmission. 
 Signals produced bypassing arange sweep voltage (orcurrent) through aresolver toproduce anelectronic 1’1’1 oranRH1. Slowly varying voltages proportional respecti\rellf tothe sine and cosine ofthe scanner angle, which are used tocontrol sa\vtooth generators insuch away that they produce s\veep components equivalent to(3). This isspoken ofas“pre-time-base” resolu- tion. 
 SURFACE HEIGHT 33(  IS DERIVED FROM THE  TIME DELAY TO THE MIDPOINT OF THE WAVEFORMS LEADING EDGE RISE /NE THOUSAND OR MORE SUCH WAVEFORMS AVERAGED OVER ONE SECOND CORRESPOND TO A MEAN RANGE ESTI 
 The measurement angles  shown in Table 23.3 are defined in  Figure 23.9, which is a clutter-centered  coordinate system similar to those  used in all the measurement programs.  Because terrain and sea are reciprocal  media, qi and qs are interchangeable in  the subsequent data. Two measurement sets are of inter - est: in plane, where f = 180°, and out of  plane, where f < 180°. 
 Philips Telecom. Rev.,  vol. 25, no. 
 THEELECTRONICALLY STEERED PHASED ARRAY ANTENNA INRADAR293 saturation beforeanewvalueofphaseshiftcanbeapplied. Thephaseshiftofaferritedeviceis especially sensitive totemperature. AchangeofIOCmightresultina 1°phasechange. 
 SUPPORTED PARABOLOID REMAIN FIXED   4HE BEAM MOVEMENT IS BY SPECULAR REFLECTION  TWICE THE ANGLE OF THE MIRROR TILT 4HIS PROVIDES A COMPACT STRUCTURE FOR A GIVEN ANGLE COVERAGE REQUIREMENT   4HE NORMALLY LIGHTWEIGHT MIRROR AND THE  BEAM DISPLACEMENT VERSUS MIRROR TILT ALLOW REDUCED SIZE AND VERY RAPID BEAM SCAN WITH LOW SERVO DRIVE POWER 4HE COMPACTNESS AND LIGHTNESS ARE  PARTICULARLY ATTRACTIVE FOR AIRBORNE APPLICATIONS  SUCH AS THE 4HOMPSON 
 Nikonowicz, J.; Kubczak, P .; Matuszewski, Ł. Hybrid detection based on energy and entropy analysis as a novel approach for spectrum sensing, Signals and Electronic Systems (ICSES). In Proceedings of the International Conference, Krakow, Poland, 5–7 September 2016. 
 13.1 iron-cored coils forthis purpose aresketched inFig. 13.2 and pictured in Fig. 13.3. 
 119. Johnson. C. 
 IEEE T,·<111s .. vol. AFS-7. 
 DIMENSIONAL IN DOPPLER FREQUENCY AND ANGLE  ADAPTIVE FILTER MIGHT BE REQUIRED THIS IS PARTICULARLY TRUE WHEN THE STATIS 
 ERROR VOLTAGES FROM THE DIFFERENCE SIGNALS 4HE PHASE DETEC 
 Therefore two to three stages of the IF amplifier mi.1st  be gain-controlled to accommodate the total dynamic range. The middle stages are usually the  ones controlled since the first stage gain should remain high so as not to influence the noise  figure of the mixer stage. It is also best riot to control the last IF stage since the maximum  undistorted output of an amplifying stage is reduced when its gain is reduced by the applica­ tion of a control voltage. 
 SIGNAL  % FIELDS CANNOT BE CONTROLLED INDEPENDENTLY )F INDEPENDENT CONTROL COULD BE PROVIDED  THE IDEAL WOULD BE APPROXIMATELY AS DESCRIBED IN &IGURE   WITH TWICE THE DIMENSION  FOR THE DIFFERENCE SIGNALS IN THE PLANE OF ERROR SENSING THAN FOR THE SUM SIGNAL  ! TECHNIQUE USED BY THE -)4 ,INCOLN ,ABORATORY TO APPROACH THE IDEAL IS A  
 TO 
 TRACING BASED ON -ARTYNS 4HEOREM CAN BE APPLIED TO STORED SEMI 
 Wiesner: Correlation Functions and Communication Applications, Electronics,  vol. 23, pp. 86-92, June, 1950. 
 CALLED RAIN CLUTTER CONTROL  WHICH ALLOWS THE TARGET 
 ETER v -ICROWAVE *  VOL   PP n     3 0 'OGINENI  & ! (OOVER  AND * 7 "REDOW  h(IGH 
 The spectral spread in  velocity is with respect to the mean velocity, which for ground clutter is usually zero. Rain and  ro u 60 - 50  2 40 u  0  C  OJ  ~ 30 - > 0 .. 0. 
 DOM MOTION IS LIMITED TO SMALL ASPECT CHANGES SUCH THAT THE AMPLITUDES OF THE ECHOES FROM THE INDIVIDUAL REFLECTORS VARY LITTLE OVER A PERIOD OF A FEW SECONDS  AND CHANGE IN RELATIVE PHASE IS THE MAJOR CONTRIBUTOR %XCEPTIONS ARE LARGE FLAT SURFACES WITH NARROW REFLECTION PATTERNS !N EXAMPLE OF A TARGET CONFIGURATION IS A DISTRIBUTION OF REFLECTING SURFACES THAT  CHANGE IN RELATIVE RANGE WITH TARGET MOTION ! TYPICAL PULSE AMPLITUDE TIME FUNCTION IS A SLOWLY VARYING ECHO AMPLITUDE  4HE LOW 
 With theconstants shown, theoutput volt. age pulse has anominal duration of1psec at12kvand 12amp. The maximum duty-ratio limit, setby the 715B tube, is1/1000.Transformer ratio Ifhigher powers arerequired, ~ac~-C=200 ~P,/ ~:,:, ATEP=1200 V itisquite practical touse several ‘*IIIITog[ldof 715B’s inparallel. 
 CLUTTER RATIO WILL BE SUF 
 But before we can produce our fluorescent picture  we must achieve two things: we must first focus our  electron stream into a beam; then we must find ready  means of deflecting it to make the desired picture.  Disposition of the electrodes in the CRT is really a  problem in electron optics, a new branch of physics  requiring a volume for adequate treatment, but it will  be appreciated that if the electron stream is being  _ “pulled away’ from the cathode through a cylinder about  . ON THE SCREEN 63  eight inches away, and charged positively at some 3000  volts, then a similar small ring or cylinder only an inch  away from the cathode, and given a small negative  charge, not only will tend to keep the stream back to  the cathode (and so retard its outward velocity), but  will also repel the stream at the point of the ring, and  so narrow the beam’s diameter. 
 197.  76. F. 
 In sub-  sequent chapters we shall investigate these systems and  see how they work and what they provide both for  military and peacetime needs, but this is an appropriate  moment to put some of these systems in their proper  perspective. Obviously the technical ingenuity of radar  will be productive of systems to aid safer, swifter trans-  port. But pulse-system radar is not the only technique  which can be so applied, and there is a considerable  future for systems such as the QM (Decca) and the  Console, which are ‘radar’ methods in the generic sense,  but which are not pulse methods; their background is  the normal continuous-wave transmission. 
 J. Portmann, J. Moore, and W. 
 TIONS ARE TIME 
 The separation of the receding  doppler signals from the approaching doppler signals may be accomplished with a technique  similar to that shown in Fig. 3.8. Quantitative measurements of the target-to-clutter enhance-  ment of this technique are not known, but it has been saids9 that "small targets moving in one  direction could be easily detected in the presence of clutter signals exceeding the target return  by many orders of magnitude." The effectiveness of this technique is limited by the degree of  symmetry of the clutter spectrum, the need for a sufficient averaging time, and by the assump-  tion that the clutter fluctuations are large compared to other factors that might affect the  symmetry of the receiver spectrum. 
 For some purposes, where beacons ofshort range areto beused inconnection with landing systems, this might prove tobea useful method. The second method involves reducing the ratio ofthe number of replies tothenumber ofinterrogations tokeep thetotal number ofreplies within the safe limit. The beacon display ofallinterrogators issome- what impaired ifthere issufficient overinterrogation toreduce this ratio markedly, but there isnodiscrimination against thefar-off interrogators. 
 IRE,  vol. 21, pp. 421-433, May, 1961. 
 fi,. SEC. 3.5] THE CORNER REFLECTOR 67 3.5. 
 TIONS IS APPLIED TO THE DATA ! COARSE TWO 
 proach to defeating noise jamming is to increase the radar's transmitter power. This technique, when coupled with "spotlighting" the radar antenna on the tar- get, results in an increase of the radar's detection range. Spotlighting or burnthrough modes might be effective, but a price must be paid. 
 NADIR ANTENNA ORIENTATION A SCATTEROMETER EXPERIMENT  'EOS 
 Figure 17.3 illustrates the various clutter doppler frequency regions as a func- tion of the antenna azimuth and relative radar and target velocities, again for an unfolded spectrum. The ordinate is the radial, or line-of-sight, component of tar- get velocity in units of radar platform velocity, so that the main-beam clutter re- gion is at zero velocity and the sidelobe clutter region frequency boundaries vary sinusoidally with antenna azimuth. Thus, it shows the doppler regions in which the target can become clear of sidelobe clutter. 
 W. Jr. and J. 
 BAR CIRCUIT  WHICH CAN BE  USED IF THE PEAK POWER IS LESS THAN  TO  K7 4HE 2AYTHEON 1+7 
 ENCES THAT CONTRIBUTE TO THE BANDWIDTH SENSITIVITY OF A PHASED ARRAY &OR A PARALLEL 
 An excellent description of the electronic battle in World War I1 between  the Germans and the Allies, with many lessons to offer, is the book " It~strtlrnertts of Dcrrkt~ess"  by Price.I3  The French efforts in radar, although they got an early start, were not as energetically  supported as in Britain or the United States, and were severely disrupted by the German  occupation in 1940.12 The development of radar in Italy also started early, but was slow. There  were only relatively few Italian-produced radars operationally deployed by the time they left  the war in September, 1943. The work in Japan was also slow but received impetus from  disclosures by their German allies in 1940 and from the capture of United States pulse radars  in the Philippines early in 1942. 
 Helgostam and B. Ronnerstam, “Ground clutter calculation for airborne doppler radar,” IEEE  Transactions on Military Electronics,  vol. MIL-9, pp. 
 Figure 16.43126 shows the frequency variation of s 0  for various kinds of ice. Shore-fast ice is grounded to the bottom at the shoreline; in  this case, it is probably MY . Gray ice is one of the types thinner than FY . 
 13 of "Radar Techniques for Detection,  Tracking, and Navigation." W. T. Blackband (ed.), Gordon and Breach Science Publishers, New  York. 
 If, for  example, the radar range is extended against surface targets by the presence of a surface duct,  air targets just above the duct that would normally be detected might be missed.  Atmospheric ducts are generally of the order of 10 or 20 meters in height, never more than  perhaps 150 to 200 meters. Propagation within a surface duct is similar to propagation within  a waveguide with a" leaky top wall." A duct supports only certain modes of propagation and  does not readily support propagation below a critical wavelength. 
 'RAZING 3CATTERING FROM "REAKING 7ATER 7AVES 5SING  AN )MPEDANCE "OUNDARY --'4$ !PPROACH   )%%% 4RANS !NTENNAS 0ROPAGAT   VOL   NO    PP n  *ANUARY   $ " #OAKLEY  0 - (ALDEMAN  $ ' -ORGAN  + 2 .ICOLAS  $ 2 0ENNDORF  , " 7ETZEL   AND # 3 7ELLER  h%LECTROMAGNETIC SCATTERING FROM LARGE STEADY BREAKING WAVES v  %XPERIMENTS  IN &LUIDS  VOL   NO   PP n  -AY   - 2 +ELLER  " , 'OTWOLS  7 * 0LANT  AND 7 # +ELLER  h#OMPARISON OF OPTICALLY 
 6 Quadriphase Waveform Performance Summary36 ch08.indd   24 12/20/07   12:50:39 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 
 WAY ANTENNA VOLTAGE PATTERN 4HIS ASSUMPTION OF A LINEAR SYSTEM MAY BE UNREALISTIC FOR SOME  PRACTICAL -4) SYSTEMS  WITH RELATIVELY FEW HITS PER BEAMWIDTH  HOWEVER  AS DISCUSSED IN 3ECTION  4HE SCANNING LIMITATION DOES NOT APPLY TO A SYSTEM THAT CAN STEP 
 9.6b. The power splits equally at the first junction and  because of the 90° phase advance on passing through the slot, the energy recombines in the  receiving attn and not in the dummy-load arm.  The power-handling capability of the balanced duplexer is inherently greater than that of  the branch-type duplexer and it has wide bandwidth, over ten percent with proper design. 
 Thus one might ha~-e arepetition rate, ancl soanoise bandwidth, of,forexample, 10cps while lm~-ing afrequency swing of4031c sec., which \\-ould gi~’e range accuracy corresponding roughly toa*-psec pulse. And this latter would beachie~-ed without awidebaml i-for~-ideo. If,however, ~~eattempt tomodify the system soastoallow the presence ofclutter, and therefore also adopplei- shift ofthesignal coming from thetarget, two difficulties arise. 
 TION IS AVAILABLE AT WWWTICRACOM 4HE /35 
 IEEETrailS..vol.AES-12. pp. 40540X.May.1976. 
 Atype K display system isused which shows thetwo responses side-by-side ona 12-in. scope. From the relative in- tensities and therange oftheaircraft, height can bededuced. 
 STATE AMPLIFIERS !T THE 5NIVERSITY OF +YOTO  *APAN  THE ANTENNA 
 The range of interest is 0 I 2u, I uo which covers the span  from uniform iliuminations to a taper so severe that the illumination drops to zero at the ends  of the array. (The array is assumed to extend a distance dl2 beyond each end element.)  The above applies to a linear array. Similar results apply to a planar aperture;"." that is,  the beamwidth in the plane of the scan varies approximately inversely as cos 00, provided  certain assumptions are fulfilled. 
 17.9.—Hypothetical method oftransmitting synchro data by c-w, themethod ofsynthesis hasanimportant bearing onthechoice ofarelay method, abrief discussion ofthe use ofthe data will begiven. T\vo general methods are possible: mechanical duplication ofthe scanner motion atthe receiving station (asinthe previous cases), oruse ofthe sine and cosine voltages toproduce the two necessary PP1 range-sweep “omponents.” Derivation ofmechanical motion from sine and cosine information requires theuseofaservomechanism. Practically speaking, itisneces- sary, inorder toreproduce themechanical motion, toprovide a-cvoltages proportional tosine and cosine, aswell asavoltage ofconstant amplitude for reference purposes. 
 BAND 'A!S POWER &0 
 78. Richter, J. H.. 
 Not only does it provide a suitable navigational tool but also its  transmissions are identical to conventional commercial traffic, allowing safe naviga - tion without necessarily highlighting a vessel’s military purpose. The biggest influence on the requirements of shipborne CMR comes from the  International Maritime Organization1 (IMO). A United Nations agency based in  London, IMO is concerned with international maritime safety and the protection of  the marine environment. 
 B. J.C. Moore. 
 62. K. Gerlach, “Second time around radar return suppression using PRI modulation,” IEEE  Transactions on Aerospace and Electronic Systems , vol. 
 16.5 MEASUREMENT TECHNIQUES   FOR GROUND RETURN Special-purpose instrumentation radars and modified standard radars may be used to  determine the ground return. Since the ground return is almost invariably due to scatter - ing, these systems are termed scatterometers . Such systems may use CW signals with  or without doppler processing, but they may also use both pulse and FM techniques. 
 They include  the theories of geometrical and physical optics, the geometrical and physical theories  of diffraction, and the method of equivalent currents. These approximations are dis - cussed in Section 14.3. Other approximate methods not discussed here are explored in  detail in some of the references listed at the end of this chapter . 
 IEEE T rans. Aerosp. Electron. 
 Itshouldbenotedthattheadaptive thresholding oftheautomatic detector cancausea worsening oftherange-resolution._B.yanalQ~~o theangu1aL[~~Ql~ti~n theangle coordinateB8itwo~seemapriorithattW-Q_tl!rgets mightberesolved inrangeifthdr separation isabou~»fthe pulsewidth.However, ithas-been shown89tha(;ith automatic ;:::r-"_•.•..".•...__ _ detection theprobability ofresolvmg targetsinrangedoesnotriseabove0.9untiltheyare separated by2.5pulsewidths.Toachievethisresolution alog-video receivershouldbeused andthethreshold shouldbeproportional tothesmallerofthetwomeanscalculated froma numberofreference cellsoneithersideofthetestcell.Italsoassumes thattheshapeofthe returnpulseisnotknown.Ifitis,itshouldbepossible withtheproperprocessing toresolve targetswithinapulsewidth: Whenmorethanoneradar,covering approximately thesamevolume inspace,are locatedwithinthevicinityofeachother,itissometimes desirable tocombine theiroutputsto formasingletrackfileratherthanformseparate tracks.83•97-S>:lSuchanautomatic detection andintegrated tracking system(ADIT)hastheadvantage ofagreaterdataratethananysingle radaroperating independently. Thedevelopment ofasingletrackfilebyuseofthetotal available datafromallradarsreducesthelikelihood ofalossoftargetdetections asmightbe causedbyantenna lobing,fading,interference, andcluttersinceintegrated processing pe.:rmils thefavorable weighting ofthebetterdataandlesserweighting ofthepoorerdata. REFERENCES 1.Dunn,J.H.,D.D.Howard, andK.B.Pendleton: Tracking Radar,chap.21of"RadarHandbook," M.I.Skolnik(ed.),McGraw-Hill BookCo.,Inc.,NewYork,1970. 
 MIXED PORTION OF THE ATMOSPHERE IS CALLED THE  HOMOSPHERE  WHILE  THE HIGHER  STRATIFIED PORTION IS CALLED THE  HETEROSPHERE 7ITHIN THE HETEROSPHERE LIES THE  IONOSPHERE 4HE BOTTOM PORTION OF THE HOMOSPHERE IS CALLED THE TROPOSPHERE 4ROPOSPHERE 4HE TROPOSPHERE EXTENDS FROM THE %ARTHS SURFACE TO AN ALTITUDE  OF  TO  KILOMETERS AT POLAR LATITUDES   TO  KILOMETERS AT MIDDLE LATITUDES  AND UP TO  KILOMETERS AT THE EQUATOR )T IS CHARACTERIZED BY A TEMPERATURE DECREASE WITH HEIGHT 4HE POINT AT WHICH THE TEMPERATURE CEASES TO DECREASE WITH HEIGHT IS KNOWN AS THE TROPOPAUSE 4HE AVERAGE VERTICAL TEMPERATURE GRADIENT OF THE TROPOSPHERE VARIES  BETWEEN  AND  #ELSIUS PER KILOMETER 4HE CONCENTRATIONS OF GAS COMPONENTS OF THE TROPOSPHERE VARY LITTLE WITH HEIGHT   EXCEPT FOR WATER VAPOR 4HE WATER VAPOR CONTENT OF THE TROPOSPHERE COMES FROM EVAP 
 59 63, April. 1970. 222 INTRODUCTION TO RADAR SYSTEMS  41. 
 FREQUENCY DISPERSION  OFTEN EXPRESSED IN TERMS OF APERTURE 
 Technol. Electron ., vol. 37, pp. 
 25.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 Radar Digital   Signal Processing James J. Alter   Jeffrey O. Coleman Naval Research Laboratory 25.1 INTRODUCTION The exponential growth in digital technology since the 1980s, along with the cor - responding decrease in its cost, has had a profound impact on the way radar systems  are designed. 
 LATE THE TEMPORAL CHARACTERISTICS OF  THE ACTUAL RADAR RETURN 2 EPEATERS GENERATE COHERENT  RETURNS THAT ATTEMPT TO EMULATE THE AMPLITUDE  FREQUENCY  AND TEMPORAL CHARACTERISTICS OF THE ACTUAL RADAR RETURN 2EPEATERS USUALLY REQUIRE SOME FORM OF MEMORY FOR MICROWAVE SIGNALS TO ALLOW ANTICIPATORY RETURNS TO BE GENERATED THIS IS USUALLY IMPLEMENTED BY USING A MICROWAVE ACOUSTIC MEMORY OR A DIGITAL 2& MEMORY $2&-   )N A $2&- SYSTEM  THE INPUT 2& SIGNAL IS GENERALLY FIRST DOWN 
 87. Gent, H.. I. 
 All the modes except the n mode are  degcl~crate; tliat is. tliey can oscillate at two different frequencies corresponding to a rotation  of tile standing-wave pattern, where the positions of the nodes and antinodes are interchanged.  el'lirls tliere arc N - 1 possible frequencies in wl~ich the magnetron can oscillate. 
 13. D. S. 
 Thecourseonwhichthisbookisbasedisaprovenmethodforintroducing thestudent tothesubjectofelectronic systems.Itintegrates andappliesthebasicconcepts foundinthestudent's othercourses andpermits theinclusion ofmaterial important to thepractice ofelectrical engineering notusuallyfoundinthetraditional curriculum. Instructors ofengineering coursesliketousetextsth3;tcontainavarietyofproblems that canbeassigned tostudents. Problems arenotincluded inthisbook.Although theauthor assignsproblems whenusingthisbookasatext,theyarenotconsidered amajorlearning technique. 
 TION  ! COMMON METHOD TO ALLOW FOR WIDEBAND FREQUENCY MEASUREMENTS IS BASED ON INTERFEROMETRIC DEVICES THAT PROVIDE INSTANTANEOUS FREQUENCY MEASUREMENT WITH GOOD ACCURACY AND ARE ABLE TO REJECT SIGNAL INTERFERENCE WITH LOWER INTENSITY 4HE HIGHER SENSITIVITY AND PROBABILITY OF INTERCEPTION ARE PROVIDED BY WIDE INSTANTANEOUS BAND SUPERHETERODYNE RECEIVERS FOLLOWED BY BANKS OF CONTIGUOUS RECEIVER CHANNELS . Ó{°{  2!$!2 (!.$"//+  3EVERAL TECHNOLOGIES HAVE BEEN PROPOSED IN THE PAST SUCH AS SURFACE ACOUSTIC WAVE  3!7  FILTERS AND "RAGG CELLS 4HE PREFERRED APPROACH IS BASED ON DIGITAL RECEIVERS  THAT INTEGRATE WIDEBAND SPECTRAL ANALYSIS AND SEVERAL POST 
 89. Croney. J : Clutter 011 Radar Displays. 
 AXIS  DIRECTION OF THE RADAR DISPLAY  h(EADv REFERS TO THE SHIPS HEADING (EAD 
   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°Ç£  % "ROOKNER  h!RRAY RADARS !N UPDATE v  -ICROWAVE *  VOL   PT )  PP n  &EBRUARY   PT ))  PP n  -ARCH   7 ! (ARMENING  h! LASER 
 For a seven-stage generator, the modulo-2 sum of stages 6 and 7 is fed back to the input. For an eight-stage generator, the modulo-2 sum of stages 4, 5, 6, and 8 is fed back to the input. The length N of the maximal-length sequence isFIG. 
 1.4.Ellis,J.G.:DigitalMTI,ANewToolfortheRadarUser,MarconiRev.,vol.36,pp.237-248, 4thqtr., 1973. 15.Fletcher, R.H.,Jr.,andD.W.Burlage: AnInitialization Technique forImproved MTIPerformance in PhasedArrayRadars,Proc.IEEE,vol.60,pp.1551-1552, December, 1972. 16.Hsiao,J.K.:CombFilterDesign,NavalResearch Laboratory, Washington, D.C.Memorandum Report 2433,May,1972.. 
 TER BUT A NEW DESIGN TO USE SOLID 
 \'olume 8. Number 2 (1987) MacArthur, Marth, Wall -The GEOSA TRadal' A/fill/efer  Figure 5-Block diagram of the  digital chirp generator.  200~--~--~--~----r---~--~---'----'  (J)  ~ 150  ~  Q)  ~ 100  0. 
 \¥ AWN a : og  MMO Qa nw!  SEE 2 AWN WWW  eS  \\ \ ~  AES A FEW LINES OF A GEE LATTICE  A is the master, B and C are the slaves. The base-line is 100 miles,  and the time-delay in microseconds is shown in each isochrone. By  taking a fix on each base and plotting, the navigator can pin-point his  position. 
 GRWA VE seems to underestimate attenuation  slightly at 7.72 MHz but over-estimate at 12.42 MHz. The sea roughness in this case  was low (sea state 1–2). The impact of sea roughness on signal amplitude can be taken  into account by using the expressions for roughness loss derived by Barrick.159 Another surface wave propagation modeling code has been developed by Sevgi,160  paying particular attention to the calculation of propagation over hybrid paths with  multiple islands. 
 EXTRACTION OF INFORMATION AND WAVEFORM DESIGN 439  12. Deley, G. W.: Waveform Design, chap. 
 ING )T IS BETTER TO ZERO IN ON THE BANDWIDTH OF INTEREST BY NONSWITCHED FILTERS LATER IN THE  RECEIVER  USING A VARIABLE FREQUENCY LOCAL OSCILLATOR TO POSITION THE DESIRED SUBBANDS  OVER THE SELECTIVE FILTERS /F COURSE THE SWITCHED ,/ CAN ALSO  SUFFER FROM IMPERFEC 
 SHAPE FACTOR !"3&  IS  D" 4HE !"3& IS THE NUMBER BY  WHICH THE MIDBEAM  3. MUST BE REDUCED SO THAT THE DETECTION CURVES GENERATED FOR  EQUAL SIGNAL AMPLITUDES CAN BE USED FOR THE SCANNING RADAR L 4HE COLLAPSING LOSS FOR THE LINEAR DETECTOR CAN BE SEVERAL DECIBELS GREATER THAN THE  LOSS FOR A SQUARE 
 The position of the target echo in the frequency spectrum depends upon its velocity  relative to that of the radar aircraft. If the target aircraft approaches the radar aircraft head on  (from the forward sector), the doppler frequency shift of the target will be greater than the  doppler shifts of the clutter echoes, as shown in Fig. 4.36. 
 PORATE HIERARCHY OF COMBINED TRANSISTORS 4HE OUTPUTS OF ALL FINGERS ARE REQUIRED TO BE COMBINED IN PHASE AND THEN IMPEDANCE 
 ,   Ê  " 
 UTD is essentially an enhance - ment of GTD wherein localized GTD singularities are corrected. The diffraction terms in  UTD increase the accuracy of the basic GO solution and will properly predict the pattern  asymmetries of more generalized reflector geometries. Like PO, GTD/UTD methods   will generally provide high-fidelity pattern predictions for most reflector systems   (center-fed, offset, single, dual, etc.) as long as the reflector size is approximately 5 l or  larger. 
 20.3/?, the exact target height can be calculated as follows: hT = [(R0 + /O2 + Rf + 2(/?0 + ha)RT sin 6r]1/2 - RQ (20.3) . (b) FIG. 20.3 Geometric considerations, (a) Flat-earth geometry, (b) Spherical- earth geometry. 
 (The value of ii, is a rnaxirnum when SIN = 0.)  Coherent detector. The cohere11 t detector (Fig. 10.4) consists of a reference oscillator feeding a  balanced mixer. 
 Fornaro, G.; Seraﬁno, F.; Soldovieri, F. Three-dimensional focusing with multipass SAR data. IEEE T rans. 
 2s8. Receivers, Ideal and Real.—Returning tothe original problem, letusconsider therudimentary receiver shown inFig. 2.3. 
 and i = wavelength, cm.  Figure 13.13 One-way attenuation (dB/  km) in rain at a temperature of  18°C. (a) Drizzle- 0.25 mm/h; (h) light  rain---I mm/h; (c) moderate rain- 4  mm/h; (d) heavy rain--16 mm/h; (o)  excessive rain- 40 rnmlh. 
 ON 
 [ CrossRef ] 309. Sensors 2019 ,19,6 3 17. Bentes, C.; Velotto, D.; Tings, B. 
 The purpose of the above listing is to indicate that radar is dynamic. Not all the new advances made since the first edition of this handbook are listed, nor does the list include all the new material discussed in this edition. There continue to be significant advances in the application of new technology and in the appearance of new applications. 
 To achieve the best resolution, the synthetic aperture time should be [ 31]: T=0.886cR DV SAR f(12) where fis the radar frequency, cis the speed of light, Ris the nearest range between the platform and imaged target, VSAR is the platform velocity, and Dis the actual antenna aperture. The synthetic aperture time, as a matter of fact, is the integrating time for the backscattered energy of a target to be well focused. For the same set of antennae, a longer integrating time is needed for a higher radar frequency, according to Equation (12). 
 §©¶¸PVV P=            )N IMPLEMENTING AN )1 DEMODULATOR  IT IS IMPORTANT TO PROVIDE WELL 
 THE 
 A discrete setoffixed indices, oracontinuously variable index, may be provided; forsome techniques ofdisplay synthesis, thelatter isnot easy toachieve. The controls ofmovable markers, bo~h ofrange and ofangle, are often connected todevices providing remote data transmission. 6.3. 
 SHARE ONBOARD ELECTRONICS AS WAS  THE CASE WITH THE SCAT 
 The smallest bit size is about l /2 or l, with the precise setting adjusted by FIGURE 13.27  Generation of grating lobes by a change of frequency FIGURE 13.28  Loss of gain and grating-lobe amplitude as functions of bandwidth (phased  subarrays with time delay, scanned 60 °). The value of the grating lobe will be modified by the  element pattern. ch13.indd   44 12/17/07   2:40:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.936x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 after dead time, the transmitter, power supply, and heating effects must be allowed to  settle before good MTI performance can be expected. The duration of the settling time  depends on the system parameters and the requirements. 
 REFERENCES I.North,D.0.:AnAnalysis oftheFactorsWhichDetermine Signal/Noise Discrimination inPulsed­ carrierSystems, RCATech.Rept.PTR-6C, June25,1943(ATI14009).Reprinted inProc.IEEE, vol.51,pp.1016-1027, July,1963. Thefollowing references (2to8)appearinIRETrans.,vol.IT-6,no.3,June,1960,specialissueon Matched Filters: 2.Turin,G.L.:AnIntroduction toMatched Filters,pp.311-329. 3.Westerfield, E.C,R.H.Prager,and1.L.Stewart; Processing GainsagainstReverberation (Clutter) UsingMatched Filters,pp.342-348. 
 5.6 Block diagram of (a) a corporate-combined power amplifier and (b) a space-combined power amplifier.(a)PRADIATED — nzA — losses PRADIATED— nzA . rows of a space-combined array. The phased array configuration is an example of the space-combined approach wherein each radiating antenna element is fed by an amplifier module and the wavefront is formed in space. 
 The thickness may  he reduced by zoning just as with a dielectric lens. The bandwidth of a zoned metal-plate lens  is larger than that of an u11zoned lens, but the steps in the lens contour scatter the incident  energy in undesired directions, reduce the gain, and increase the sidelobe level. An example of  an X-band metal-plate zoned lens is shown in Fig. 
 PURPOSE PROCESSORS  MORE  AND MORE OF THE RADAR SYSTEM FRONT END WILL MOVE FROM ANALOG TO DIGITAL DESIGNS &OR EXAMPLE  &IGURE  SHOWS A TYPICAL DIGITAL RECEIVER FOR A RADAR FRONT END  WHICH REQUIRES TWO STAGES OF ANALOG DOWNCONVERSION TO BRING THE 2& SIGNAL DOWN TO AN )& THAT CAN BE SAMPLED BY AN !$# 4HIS IS REQUIRED BECAUSE OF THE CHARACTERISTICS OF THE !$#  WHICH TYPICALLY HAS POORER SIGNAL 
 II—Suppl., GEC-AEI (Electronics) Ltd., Memo. SLM 2116 (Suppl.), Stanmore, England, July 1969. 111. 
 The only apparently successful application of  step-frequency has been in ground-based instrumentation radars, where it is less  expensive to implement and more time is available for data collection (Knott et al.,26  pp. 35, 540). Nevertheless, for the moment, we assume the step-frequency waveform because  it provides a much simpler example for explaining the principle of range resolution. 
 POWER AMPLIFIERS CAN ADD APPRECIABLE AMOUNTS SO CARE MUST BE EXERCISED IN THE AIR OR LIQUID COOLANT FLOW SYSTEM DESIGN )F THE RADAR IS TO PERFORM WIDE 
 Its precessing 400-km orbit, inclined at 35 °, supports temporally and spatially sparse  atmospheric coverage over tropical land and sea. The radar provides a three-dimen - sional structure of rainfall from the surface to an altitude of 20 km. When combined  with data from the passive microwave radiometer (TMI), PR data support improved  accuracy of rainfall retrievals. 
 SCANNING RADAR ALTHOUGH NONDOPPLER  FOR EFFECTIVELY OBTAINING SNAPSHOTS OF CONVECTIVE  STORMS +EELER AND &RUSH  DISCUSS DESIGN CONSID 
 18.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 main objective of a space-based altimeter is also to measure the distance between  the radar and the surface, the most common application is determination of the local  sea level relative to the Earth’s geoid,§ rather than the height of the spacecraft. The  reference for this measurement—the orbital height of the spacecraft—must be known  by other means to within a few centimeters. Sea-surface height is a function of many  geophysical parameters, such as current flow, an El Niño event, and variations in the  ocean’s depth. 
 It is not always appreciated that loss in the array feed is equivalent to a loss in antenna power  gain.  There are at least three basic.concepts for feeding an array. The constrained~feed utilizes  waveguide or other microwave transmission lines along with couplers, junctions, or other  power distribution devices. 
 Small steering increments are possible with quantized phase shifters. For example, a linear  array of 100 elements can be steered in increments of about 0.01 beamwidth with 3-bit phase  shifters."  8.9 COMPUTER CONTROL OF PHASED-ARRAY RADAR - ' '  A computer is a necessary part of a phased-array radar. It is vital in applications where  flexible, multifunction operations are desired, as in satellite surveillance, air defense systems,  ballistic missile defense, and multifunction airborne radar. 
 3. R. K. 
 Range Coding. -Codes readily visible onthePPI, asinFigs. 8.2a and 8.2b,areobtained byhaving thetrigger operate acoder that causes the emission ofanumber ofreply pulses. 
 Quadratic phase errors caused by long-term drift in the stable clocks are usually smaller than allowable short-term sinusodial phase errors and can often be ignored. In.most types of SAR images, the integrated sidelobe ratio (ISLR) is an important criterion for image quality. It is a measure of the energy from a par- ticular target that appears at image locations other than that corresponding to the target. 
 (Court<'sy v( Wesli11ylio11se. Inc.)  Table 14.l Characteristics of two air traffic control radars28•46·56  ARSR-3 ASR-8  Frequency band L s  Frequency 1250-1350 MHz 2700-2900 MHz  Instrumented range 200 nmi (370 km) 60 nmi (Ill km)  Peak power 5MW 1.4 MW  A vcrage power 3.6 kW 875 W  Noise figure 4 dB 4 dB  Pulse width 2 ps 0.6 }lS  Pulse repetition frequency 310-365 Hz 700-1200 Hz  1040 Hz (ave)  Antenna rotation rate 5 rpm 12.8 rpm  Antenna size 12.8 m by 6.9 m 4.9 m by 2.7 m  Azimuth beamwidth 1.25° 1.350  Elevation coverage 40° 30°  Antenna gain 34 dB 33 dB  Polarization hor, vert, or circular vert or circular  Blind speed 1200 knots 800 knots  MTI improvement factor 39 dB 34 dB . OTIIER RADAR TOPICS 539  vehicle on which the radar is carried; reliability (mean time between railures). 
 78. Saxton, J. A.: The Influence of Atmospheric Conditions on Radar Performance, J. 
 LINE RECOGNITION TO ASSIST WITH COORDINATE REGISTRATION  MEASUREMENTS OF THE IONOSPHERE FOR ASSIMILATION INTO IONOSPHERIC MODELS  EXTRACTION OF ECHOES FROM REMOTE BEACONS DEPLOYED TO ASSIST WITH COORDINATE REGISTRATION AND CALIBRATION  AND MANY OTHER BYPROD 
 The spectrum of fading at a different range (or vertical angle) is different, in accord with Eq. (12.13). For many purposes, the number of independent samples is important, since these may be treated by using the elementary statistics of uncorrelated samples. 
 In Figure 10.56, both the input transducer and the output transducer are dispersive. This would result in the same impulse response as that of Fig. 10.50. 
 J., and M. B. Fishwick: Analog Waveform Generation and Processing, Electronic Progress,  vol. 
 LATE SPECIAL FUNCTIONS LIKE 'AMMA AND "ESSEL +  CODED LIBRARIES A STANDARD LIBRARY OF 7INDOWS !0)S !PPLICATION 0ROGRAMMING )NTERFACES  TO DRAW THE COVERAGE DIAGRAMS A TEMPLATE LIBRARY TO IMPLEMENT THE MATRIX ALGEBRA AN APPLICATION BASED ON -3 /FFICE %XCEL TO CODE THE "LAKE #HART o A SET OF 6ISUAL "ASIC TOOLS TO EVALUATE SOME ASPECTS  OF RADAR PERFORMANCE EG  !$# JITTER  ATMOSPHERIC LOSS  TAPERING LOSS  ETC  AND AN UNFORMATTED ARCHIVE OF RADAR DATA  AS SIMPLE !3#)) FILES  PERTINENT TO PERFORMANCE   ENVIRONMENT  TRAJECTORIES  TERRAIN HEIGHT  AND WAVEFORM 5SER 
 CAL PARAMETERS     DIRECTLY PROPORTIONAL TO THE RADAR REFLECTIVITY FACTOR  :  AND MOST  SIGNIFICANT    INVERSELY PROPORTIONAL TO R NOT R AS IN THE CASE OF POINT TARGETS  4HE RADAR SYSTEM PARAMETERS INCLUDED IN  A IN %Q  INCLUDE THE PEAK TRANSMIT  POWER 0T  THE ANTENNA SYSTEM GAIN  ' TWICE ONCE FOR TRANSMITTING AND ONCE FOR RECEIV 
 Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar.  PULSE COMPRESSION RADAR  8.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 Taylor Versus Cosine-Squared-Plus-Pedestal Weighting.  Figure 8.6 a plots the  taper coefficient F1 and pedestal height H versus the peak time sidelobe level for  cosine-squared-plus-pedestal weighting. 
 9 to 14.11 Corporate feed monopulse phased array, 9.14 Co secant-squared antenna, and STC, 2.98 COSMO-SkyMed SAR, 18.12 Costas codes, 8.25 to 8.26 Counter Battery Radar (COBRA), 13.62 Creeping waves, 14.3, 14.5 Critical frequency, in HE OTH, 20.3 Crossed-field amplifier (CFA), 10.3, 10.16 to 10.17 Crossed-field tubes, 10. 2 Cross-eye ECM, 24.42 to 24.43 Cross-pol arization jamming, 24.43 Cross-polarization tracking, 9.40 to 9.41 Crossrange resolution, 17.1 Cross section. See radar cross section Crosstalk, in tracking, 9.40 to 9.41 Crowbar, in transmitters, 10. 
 Image Quality . Looks and resolution work together to determine the image qual - ity (read “geophysical information potential”) of SAR imagery over natural terrain  composed of distributed scatterers. The governing expression is the SAR image qual - ity parameter31,113  QN r rL SAR RgAz=  (18.18) where NL is the number of (statistically independent) looks, and rRg and rAz are the  range and azimuth resolution, respectively, on the surface. 
 T.: Phased Array Feed Systems. A Survey, " Phased Array Antennas, Proceedings of the 1970  Phased Array Antenna Symposi~~m," A. A. 
 (ANSEN  h2ADAR SYSTEMS TRADE 
 M. I.: Survey of Phased Array Accomplishments and Requirements for Navy Ships,  "Phased Array Antennas." ed. by A. 
 WAVELENGTH  DUAL 
 D. Howard, and K. B. 
 ch18.indd   30 12/19/07   5:14:49 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 It is more usual, however, for transmission lines in a frequency-scan array  to have a velocity of propagation which varies with frequency; i.e., they are dispersive. A  waveguide is an example of a dispersive line. The velocity vs. 
 The flare angle is chosen such that it creates a reasonably phase-constant vertical dis - tribution at its aperture. The vertical amplitude distribution approximates to a cosine  because of the horizontally polarized field. Vertical beamwidths are typically about  25° wide at the 3 dB points. 
 The LNFE consists of an RF amplifier (typically  giving about 10 dB gain) and a balanced mixer, local oscillator, and IF head amplifier.  These are normally supplied to the radar manufacturer by specialist companies as a  complete subunit. The overall system noise figure is typically 4 to 5 dB, but lower  figures are achievable. 
 13.10. Sawtooth Generators.—The sawtooth waveforms used asa basis forrange sweeps and incertain varieties ofprecision timing circuits are practically always generated byawave-forming network that is switched onand offbysome sort ofclamp. The basic action ofallsuch devices can beillustrated bythe simple circuit ofFig. 
 A few of the most common detectors7 are shown in Fig. 8.3. Though they are shown in the figure as being constructed with shift registers, they would normally be implemented with random-access memory. 
 The availability of some distinctive target characteristic, such as its altitude, might  also prove of help when performing track association.71 Thus, the quality of the ADT will  depend significantly on the ability of the radar to reject unwanted signals.  When a new detection is received, an attempt is made to associate it with existing  tracks.96 This is aided by establishing for each track a small search region, or gate, within  which a new detection 1s predicted based on the estimate of the target speed and direction. It is  desired to make the gate as small as possible so as to avoid having more than one echo fall  within it when the traffic density is high or when two tracks are close to one another. 
 The Cassegrain antenna can, ifdesired, be designed to have a lower antenna noise tempera-  ture than the conventional parabolid. This is due to the elimination of the long transnlission  lines from the feed to the receiver and by the fact that the spillover-sidelobes from the feed see the  cold sky rather than the warm earth. Low antenna noise temperature is important in radio  astronorny or space communications, but generally is of little interest in radar since extremely  low noise receivers are not always desirable. 
 To complicate the picture still further, it is becoming increasingly clear that sea backscatter has a strong dependence on the direction of the long waves, which include swell, in the measurement area; so ideally the directional wave spectrum should be measured as well. Obviously, it is unlikely that all theseSea state 1 (smooth) 2 (slight) 3 (moderate) 4 (rough) 5 (very rough) 6 (high) 7 (very high)Wind speed, kn <7 7-12 12-16 16-19 19-23 23-30 30-45Waveheight #1/3, ft 1 1-3 3-5 5-8 8-12 12-20 20-40Duration/fetch, h/nmi 1/20 5/50 15/100 23/150 25/200 27/300 30/500 . environmental parameters will be recorded with precision in every (or even any) sea clutter measurement; so considerable variability in the basic conditions under which sea clutter data is collected by different experimenters can be expected. 
 Horizontal polar-isation was chosen as it was found that vert ical polarisation gave excessive returnsAirborne Maritime Surveillance Radar, Volume 1 1-4. from the sea and land. By late 1937 experiments had started on the use of side- looking Yagi arrays, placed on the upper surfaces of both wings (receiving antennas) and tail planes (transmit antennas). 
 NIQUES  PREFERABLY AT A POINT AS CLOSE TO THE SOURCE OF THE MISMATCH AS POSSIBLE )N A SCANNING ARRAY  THE IMPEDANCE OF A RADIATING ELEMENT VARIES AS THE ARRAY IS  SCANNED  AND THE MATCHING PROBLEM IS CONSIDERABLY MORE COMPLICATED 5NLIKE A CONVEN 
 For  a quantized rhase shifter consisting of B bits, the phase error c5 is described by a uniform  probahility density function extending over an interval ± rr./2R. From Sec 2.4 the mean square  phase error for the uniform probability density function is J2 = rr.2/3(228). Substituting into  Eq. 
 DOPPLER AMBI 
 Each stage ofi-famplification uses a6AC7 pentode with single- tuned coupling circuits. Allstages but the last have a1200-ohm load resistance, 1giving asingle-stage bandwidth ofalittle over 6lIc/sec and anover-all i-fband~\-idth ofnearly 2Me/see. The nominal gain ofthe i-famplifier is120 db. 
     "ECAUSE  TWO QUADRATURE CHANNELS CONTRIBUTE INDEPENDENT !$ NOISE  THE AVERAGE  LIMIT ON THE IMPROVEMENT FACTOR OF A FULL 
 1977.  X6 Sakarnolo. Il.. 
 It should be remembered that this results only in a stable driver, any noise generated in the power amplifier being unaffected. And, as noted above, unless the local oscillator is generated from the output of the power amplifier, which, of course, cannot be done in a pulse doppler system, this noise is uncorrelated. For- tunately, good power amplifiers driven by highly regulated supplies add ex- tremely small amounts of excess, or additive, noise. 
 C.: Optical Scanners, chap. 3 of" Microwave Scanning Antennas, vol. I." R. 
 11.8, itis apparent that aT-junction onthe narrow side ofthe guide isaparallel connection, and that theplane ofthenarrow side isaquarter wavelerigth from the effective center ofthewaveguide circuit. MICROWAVE COMPONENTS OFTHE RECEIVER After emerging from theTR switch, thereceived signal ismixed with the local-oscillator signal and the combination applied tothe crystal, in. 412 R-FCOMPONENTS [SEC. 
  %UROPE  &ANBEAMS # 66 3CAT !QUARIUS 53!   
 10,CQO10?m 3.2cm A=locm,A ~1000-—+- / s .s 5 s100 s j 10 / /‘ 0194019411942194319441945 Date100 80 : E g60 /~<10 cm 5~40 1g <=3.2 cm : 20/I /‘ A=l.25 cm 01940 1941 1942 1943 1944 1945 Date FIG. 1.5.—Historical development ofmicrowave magnetrons. However formidable this requirement appears, one ofthe most remarkable facts ofthe wartime years ofdevelopment ofradar isthat practicable pulse powers inthemicrowave frequency range (about 1000 Me/see and above) have increased byafactor ofhundreds inarelatively short time. 
 !PPLEBAUM ADAPTIVE BEAMFORMER  WHICH HAS AN OMNIDIRECTIONAL RECEIVING PATTERN EXCEPT WHERE JAMMERS ARE PRESENT 4HE PRESENCE OF JAMMERS IS INDICATED BY NULLS IN THE RECEIVING PATTERN "ECAUSE NULLS ARE ALWAYS SHARPER THAN ANTENNA LOBES  JAMMER BEARINGS CAN BE OBTAINED MORE ACCURATELY FROM THE ADAPTIVE BEAM PATTERN  AND SUPER 
 Further, the. SEC. 108] LOAD REQUIREMENTS 363 TABLE 103. 
 For example, if  the radiator is fed from a stripline phase shifter, a stripline dipole would be a logical  choice. If a waveguide phase shifter is used, an open-ended waveguide or a slot might  be convenient. At the lower frequencies, where coaxial components are prevalent,  dipoles have been favored. 
 Sea clutter,  although very variable, will have certain local characteristics, enabling more effective  optimization of the processing. In particular, the actual performance can be more eas - ily measured against design requirements. The design of high-performance antennas for VTS applications has a similarity to  air traffic control antennas, in that they both ideally require a tailored elevation pattern. 
 BIT SEQUENCES  A  ALL POSSIBLE  
 Measurements of ground return when the receiver and transmitter are separated are comparatively rare. These measurements are very difficult to make from aircraft because it is necessary that both transmitter and receiver antennas look at the same ground point at the same time and that the signal be correlated with known antenna look angles. Furthermore, it is difficult to know the polarization, and the exact size and shape of the common area illuminated by the antenna beams are sometimes difficult to determine. 
 This offset is chosen such that even if a missile hits the decoy, the  aircraft will not be damaged. The decoy can either be powered by the aircraft via the  cable or be self powered. Besides providing power to the decoy, the cable can also be  used as a data link to control jammer operation. 
 Whennobetterinformation isavailable, averyroughorder ofmagnitude estimate oftheship'scrosssectionatother-than-grazing incidence canbehadby takingtheship'sdisplacement intonstobeequaltoitscrosssectioninsquaremeters.The average crosssectionofsmallpleasure boats20to30ftinlengthmighthavearadarcross sectioninthevicinityofafewsquaremetersatXband.68Boatsfrom40to50ftinlength mighthaveacrosssectionoftheorderof10squaremeters. Theradarcrosssectionofanautomobile atXbandisgenerally greaterthanthatofan aircraftoraboat.Fromthefrontthecrosssectionmightvaryfrom10to200m2atXband, with100m2beingatypicalvalue.6sThecrosssectionincreases withincreasing frequency (up to60GHz,therangeofthemeasurements). Themeasured radarcrosssectionofamanhasbeenreported 32tobeasfollows: Frequency, MHz 410 1,120 2,890 4,800 9,3750.033-2.33 0.098-0.997 0.140-1.05 0.368-1.88 0.495-1.22 Thespreadincross-section valuesrepresents thevariation withaspectandpolarization.. 
 CIPAL METHOD FOR RADIO DETECTION AND RANGING "ISTATIC RADARS CAN OPERATE WITH  DEDICATED  TRANSMITTERS  WHICH ARE DESIGNED  FOR BISTATIC OPERATION AND CONTROLLED BY THE BISTATIC RADAR  OR WITH  TRANSMITTERS 
 Radar System Engineering  Chapter 12 – Selected Radar Applications  161        Figure 13.29  Phased -array Radar DESA , © Astrium GmbH    . Radar System Engine ering  Chapter 13 – Future Radar Systems  162     14 Future Radar Systems  Rece nt advances in RF, microwave, digital and software technology will allow the development  of software -defined Radar sensors (SDRS) in the near future. The functio nality and system pa- rameters of Radar sensors for remote sensing applications will no longer be  implemented in  hardware, but instead in downloadable software. 
 Amore complicated sys- tem that avoids this defect has been used. The dead time isnormally short but isarranged toincrease, asneeded, with increasing average rate ofinterrogation. Too short adead time can betroublesome, foritmay lead tomultiple interrogation bythe same interrogator pulse that has reached thebeacon not only directly, but also byother and longer paths involving reflection. 
 SEC. 13.11] ANGLE INDICES 517 thesecond synchro tointroduce the dilTerential setting. The two nulls will result intwo signal markers 180° apart. 
 IftheSequential Observer allowsasavingsinaverage poweroffrom8to10dBwhen implemented forasingle-range cell,thepoweradvantage decreases to3to4dBfor200-range cellsandcanevenbeaslittleas1dB.40Inaddition, th~Sequential Observer requires some­ thingmoreflexiblethantheusualrotating-antenna radar.Because ofthevariable dwelltime theantenna beam-positioning systemmustusuallybeaphased-array antenna andthedata processing mustbedigital.ThusiffullbenefitistobehadfromtheSequential Observer in radar,onlyoneorafewindependent decisions perbeamposition shouldbemade.Itmightbe employed whenonlyasingle"guard-band" isdesiredfordetecting targetswithinaselected rangeinterval, anottoousualapplication. Ithasalsobeenconsidered foruseinalow-signal densityenvironment whenthecriterion isthateithernosignalispresentoronesignalaffixed andspecified levelispresentandequallylikelytobeinanyrangeinterval. 38,39 Thetermsequential detection issometimes usedsynonymously withSequential Observer. 
 3.5a) and the receiver bandwidth would be infinitesimal. But a  sine wave of infinite duration and an infinitesimal bandwidth cannot occur in nature. The  rnore normal situation is an echo signal which is a sine wave of finite rather than infinite  duration. 
 35. J. Dyck and H. 
 52. R. Mitchell et al., “Measurements of performance of MIPIR (Missile Precision Instrumentation  Radar Set AN/FPQ-6),” Final Rept., Navy Contract NOW 61-0428 d, RCA, Missile and Surface  Radar Division, Moorestown, NJ, December 1964. 
 GYRATION  TAKEN  ALONG THE ANGULAR COORDINATE OF INTEREST  OF THE DISTRIBUTION OF THE REFLECTING AREAS OF THE TARGET  &OR EXAMPLE  IF A TARGETS REFLECTING AREAS HAVE A COS O@, 
 The projection of the radar data, followed by a two-dimensional Fourier trans- . form, can be used to form images for the most general motion of both the radar and the moving object. REFERENCES 1. 
 The radar then transmits a second pulse. The reflection from the building occurs in exactly the same amount of time, but the reflection from the moving aircraft occurs in less time because the aircraft has moved closer to the radar in the in- terval between transmitted pulses. The precise time that it takes the reflected sig- nal to reach the radar is not of fundamental importance. 
 PING COVERAGE AND SIMULTANEOUS MEASUREMENTS  WHICH  IN TURN  REQUIRE BROAD TRANSMIT AND RECEIVE BEAMS TO ACHIEVE THIS ACCURACY 4HESE REQUIREMENTS USUALLY COMBINE TO RESTRICT MULTISTATIC AIR SURVEILLANCE PERFORMANCE TO SHORT OR MEDIUM RANGES 'EOMETRIC DILUTION OF PRECISION  '$/0  ESTABLISHES MULTISTATIC LOCATION ACCURACY  AND RESOLUTION  AND IS DEVELOPED BY $ "ARTON IN #HAPTER  OF 7ILLIS AND 'RIFFITHS   '$/0 IS A FUNCTION OF THE ANGLE OF INTERSECTION   @  BETWEEN ISORANGE CONTOURS "ECAUSE  THE BISECTOR OF A BISTATIC ANGLE IS ORTHOGONAL TO AN ISORANGE CONTOUR  '$/0 CAN READILY BE DETERMINED BY THE ANGLE OF INTERSECTION  ALSO  @  OF THESE BISTATIC BISECTORS )N THE  SIMPLEST CASE  THE DOWN 
 S. Marshall: The Distribution with Size of Aggregate Snowflakes, J. Meteor.,  · vol. 
 PRIATE ##)2 NOISE SHOULD BE SELECTED OR  BETTER YET  NOISE MEASUREMENTS MADE IN SITU  &OR RADARS THAT USE AURORAL ZONE PATHS  SPECIFIC ANALYSES ARE REQUIRED AND TARGET OBSCURA 
 However, the usual photograph or drawing of a phased-array radar  seldom reveals the amount of electronic equipment behind the array face that is required to  make it a useful radar.  Another of the advantages sometimes claimed for an array radar is that it is capable of  performing more than one function simultaneously; for example, it can do surveillance of a  volume as well as track individual targets. The multifunction attribute of an array radar has  336INTRODUCTION TORADAR SYSTEMS Electronic beamstabilization. 
 [ CrossRef ] 23. Wang, L.; Huang, T.; Liu, Y. Phase compensation and image autofocusing for randomized stepped frequency ISAR. 
 19.38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 radome—a roto-dome. One beam points forward about 18 ° and the other aft by the  same angle, thereby obtaining two radial components of common target volumes. With  such a system, each antenna scans in a conical surface—one cone pointing forward,  the other one rearward—thus permitting synthesis of a dual-doppler radar system  along the aircraft track. 
 DIAGNOSIS FEATURES  WHICH CAN DETECT FAILURE AND COMMUNICATE THAT TO THE BEAM STEERING CONTROLLER FOR FAILURE COMPENSATION !%3!S CAN ACCOMMODATE UP TO  FAILURES WITH VERY LITTLE DEGRADATION IF PROPERLY COMPENSATED IN THE "3#  &ROM AN -&!2 POINT OF VIEW  THE IMPORTANT PARAMETERS ARE VOLUMETRIC DENSITIES  HIGH ENOUGH TO SUPPORT LESS THAN  WAVELENGTH SPACING RADIATED POWER DENSITIES HIGH ENOUGH TO SUPPORT  WATTS PER SQ CM RADIATED 
 The rms thermal-noise power is the thermal-noise floor  within the receive portion of IPP. This power level is given in decibels with respect  to the carrier amplitude (dBc). The thermal-noise density is obtained by dividing this  power by the PRF bandwidth. 
 The output of any stage is then a binary sequence. When the feedback connec- tions are properly chosen, the output is a sequence of maximal length. This is the maximum length of a sequence of Is and Os that can be formed before the sequence is repeated. 
 TO 
 In the radar-~i~eteorology literature, the radar pulse-extent II  (in units of length) is often used instead of cr in this equation. The factor n/4 is included to  :1ccourit for tile elliptical shape of tlie beam area. 111 some instances this factor is omitted for  convenience; however, radar meteorologists almost always include it since they are concerned  with accurate measurement of rainfall rate using the radar equation. 
 7, pp. 1077–1082, July 1999.  8. 
 For random changes in velocity at  each measurement interval (model no. 3), the gains increase to ( a, b)  = (1,1), which  is very conservative from a filter stability point of view. For white noise acceleration  sampled by radar measurements (model no. 
 J LzJ9I 14.4.—Motor circuit of1500-va and 2500-va inverters showing starting relay contractors. Shuntfield Primary Swiesfield Start 0 Startingrelay w FIO.14.5.—Addition ofauxiliary starti,,g rela~-tocircuitofFig. 144. 
 DIMENSIONAL WAVE EQUATION FOR DIELECTRIC CYLINDERS 4HE STRING DIAMETER WAS  INCH AND ITS ILLUMINATED LENGTH WAS ESTIMATED TO BE  ABOUT  FT "ASED ON A MEAN SEPARATION BETWEEN THE MEASURED 66 AND 6( DATA OF  D"  THE EFFECTIVE DIELECTRIC CONSTANT OF THE STRING WAS ESTIMATED TO BE  D R     4HIS MAY BE THE FIRST TIME THAT 2#3 MEASUREMENTS WERE EVER USED TO ESTIMATE THE DIELECTRIC CONSTANT OF A STRING 3TRINGS ARE OF INTEREST AT 2#3 TEST FACILITIES BECAUSE THEY SOMETIMES ARE USED AS hINVISIBLEv TARGET SUPPORTS &)'52%   2#3 OF A LOSSY DIELECTRIC SPHERE WITH  N      I AFTER * 2HEINSTEIN  Ú )%%%   . 
 ,UPE DESIGN ALSO IS COST 
 ELECTRONIC COUNTER-COUNTERMEASURES  24.376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 The operational methods include emission control (EMCON), the appropriate  assignment of operating frequencies to various radars, the use of combined ECCMs  to meet combined ECMs, the use of dummy transmitters to draw ECM to other fre - quencies, and so on. EMCON is a technique for the management of all EM radia - tions of a friendly system, force, or complex to obtain maximum advantages in the  areas of intelligence data reception, detection, identification, navigation, missile guid - ance, etc., over the enemy in a given situation. EMCON permits essential operations  while minimizing the disclosure of location, identification, force level, or operational  intentions to enemy intelligence receptors. 
 H{f0) = 1. The bandwidth Bn is called·the noise bandwidth and is the bandwidth of an equiva­ lent rectangular filter whose noise:.power output is the same as the filter with characteristic . THE RADAR EQUATION 19  /l(f). 
 Aeronaut. Electronics  (Dayton, Ohio), pp. 133.- 144. 
 Figure 9. Map of the GERs and Metro Networks of Wuhan city. Many subways have been built such as Metro Lines No. 
 at high power to  produce radar pulses in free space. These square-  topped e.m.f.’s are commonly produced by suitable  arrangement of a transmission line into which energy is  fed, and the wave-form is distorted to produce a square  top. But we need a switch to throw this special section  of the transmission line in series with the load, to modu-  late our centimetric oscillations; and the two common  types of switch are the thyratron (with certain modi-  fications such as the trigatron) and the ordinary spark  p!  Both such devices depend, of course, on the fact that  an electric discharge in a gas provides a conducting path. 
 Golomb, S. W.: "Shift Register Sequences," Holden-Day, Oakland, Calif., 1967, chap. 3. 
 212--213.  Brown University Graduale School. Providence, R.I., 1944. 
 Pre-Doppler, Elemental Antenna STAP.  Conceptually, the simplest reduction  in degrees of freedom is obtained by reducing the number of temporal degrees of  ch03.indd   25 12/15/07   6:03:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 However, as the following  discussion will explain, the suppression of image energy across the IF bandwidth may  be substantially less than indicated by this measurement at IF center . Time Delay and Frequency Response Imbalance.  If the responses of the   I and Q channels are not identical across the entire signal bandwidth, unwanted image  responses will occur that are frequency dependent. 
 WAY SURFACE 
 (Theapparent center ofradarreflection isthedirection oftheantenna whentheerrorsignaliszero.)Ingencral,the apparent centerofreflection mightnotcorrespond tothetargetcenter.Infact,itneednotbe confined tothephysical extentofthetargetandmaybeoffthetargetasignificant fractionof thetime.Therandom wandering oftheapparent radarreflecting centergivesrisetonoisyor jitteredangletracking. Thisformoftracking noiseiscalledanglenoise,anglescintillations, anglefluctuations, ortargetglint.Theangular fluctuations produced bysmalltargetsatlong rangemaybeoflittleconsequence inmostinstances. However, atshortrangeorwithrela­ tivelylargetargets(asmightbeseenbyaradarseekeronahomingmissile), angularlluctua­ tionsmaybethechieffactorlimitingtracking accuracy. 
 &  AND  
 Asmobility requires, themount iseasily assembled and disassembled inthe field, and only four ofitsparts exceed 80lbin weight. The antenna, aparaboloid made ofagrid ofcurved }~-in. tubes, is trimmed toanoval contour 10fthigh by3ftwide. 
 PMP $$$ P$   WHERE RM  PM  IM  $M  ARE THE MEASURED RANGE  AZIMUTH  ELEVATION  AND DOPPLER WITH  ACCURACIES RR  RP  RI  R$  RP  PP  IP  $P  ARE THE RANGE  AZIMUTH  ELEVATION  AND DOP 
 RESOLUTION RADARS HAVE RANGE RESOLUTIONS IN TERMS OF FRACTIONS OF A METER  BUT IT CAN BE AS SMALL AS A FEW CENTIMETERS 0ULSE COMPRESSION RADAR 4HIS IS A RADAR THAT USES A LONG PULSE WITH INTERNAL MODU 
 NOISE PLUS JAMMER RATIO IS DETERMINED ON THE BASIS OF THE *$O! AND THE ANTENNA RECEIVING PATTERNS THE RADAR EQUATION IS THEN APPLIED AND SUITABLE %##- SIGNAL PROCESSING SCHEMES CAN BE EMULATED TO DETERMINE TO WHICH EXTENT THE JAMMER IS ATTENUATED #OMPUTER !IDED 2ADAR 0ERFORMANCE %VALUATION 4OOL #!20%4  IS AN EXAMPLE  OF AVAILABLE SOFTWARE ON THE MARKET )N THE #!20%4  MANUAL   THE EQUATIONS  FOR CALCULATING THE CONTRIBUTIONS FROM CHAFF VOLUME CLUTTER  IN THE SIGNAL 
 1765–1767. 94. S. 
 Atabout 15,000 to20,000 Me/see theattenuation bywater vapor inthe atmosphere oftheearth begins tobecome ofconsequence. Inconditions ofbad weather, when navigational beacons aremost needed, therange of beacons atsuch frequencies would belowered somuch that they would beoflittle use. Innearly allcases, thefrequency ofthebeacon reply should bediffer- entenough from that oftheinterrogating pulses toobviate simultaneous recephion ofbeacon replies and radar echoes byonereceiver. 
       .IGHT (n 
 BAND &OR EASE OF REFERENCE  THE CONVENTIONAL SIGNAL PROCESSING STAGES RESPONSIBLE FOR TRANSFORMING THE RECEIVER OUTPUTS INTO STANDARD RADAR PRODUCTS ARE DISCUSSED IN 3ECTION   TOGETHER WITH MORE SPECIALIZED TECHNIQUES !NTENNAS &ROM THE RECEPTION VIEWPOINT  IT IS DESIRABLE TO HAVE FINE AZIMUTHAL  RESOLUTION FOR SEVERAL REASONS  INCLUDING I  TO IMPROVE TARGET LOCATION ACCURACY AND TRACKING PERFORMANCE  II  FOR DETAILED CLUTTER MAPPING  AND III  TO REDUCE THE CLUTTER AMPLITUDE LEVELS TO VALUES PERMITTED  BY SYSTEM DYNAMIC RANGE AND SLOW 
 CESS IS CALLED  DUAL 
 OVAL  ,   2- C  LEMNISCATE  ,   2- AND   D  TWO 
 L-scope. A display in which a target appears as two horizontal blips, one extending to the right from a  central vertical time base and the other to the left; both blips are of equal amplitude when the radar is  pointed directly at the target, any inequality representing relative pointing error, and distance  upward along the baseline representing target distance.  hf-scope. 
   -4) 2!$!2  Ó°È 4HE ADJUSTED PHASE 
 Raindrops may not always be perfect spheres. Their deviation from the syrnmetrical shape  of a sphere will result in the reflected signal containing some energy in that polarization  cotilponent accepted by the antenna. This limits the ability of circular polarization to reject  precipitation clutter. 
 SECTION DEFINED FOR THIS PROFILE .   3%! #,544%2  £x°Îx BY %Q  CLEARLY BEARS A RESEMBLANCE TO SOME OF THE HIGH RESOLUTION RETURNS SHOWN  IN &IGURE  -OREOVER  THESE SPIKY RETURNS ARE CORRELATED WITH JUST THE KIND OF SURFACE BUMPS AND WRINKLES AND SLOPE DISCONTINUITIES THAT HAVE BEEN IDENTIFIED AS SOURCES OF SEA SPIKES IN LABORATORY TANK MEASUREMENTS    !N EXAMPLE IS SHOWN  IN &IGURE  B  WHERE AN ULTRA 
 There are only 4 digital degrees of freedom; this means that marginal improvement of  performance in terms of PSLR can be achieved. Nevertheless, a PSLR of 25 dB was  obtained for the combination of 24 analogue weights and 4 digital weights. For the  same ULA about 20 dB of PSLR was obtained for the difference channel. 
 Backscatter from the sea can be employed as a reference level and is a gen- erally used diagnostic tool. Figure 24.1 provides examples of radar coverage and spatial resolution appro- * The comments, discussions and contributions by NRL colleagues J. Hudnall, J. 
 This is usually important only at low altitudes. It  can be reduced by an attenuator introduced in the transmission line at low altitude or by a  directional coupler or an isolator.  5. 
 TIME EFFECTS LIMIT ITS APPLICATION AT MICROWAVE FREQUENCIES  BUT VARIANTS OF GRID 
  
 Ifthecircuit shown inFig. 12.10 were connected tothedetector of Fig. 129, itwould serve very well asalimiter-amplifier. 
 ILIARY RECEIVERS )F SUBARRAY RECEIVERS ARE USED  THE NUMBER OF NULLS THAT CAN BE PLACED IN THE ANTENNA PATTERN DEPENDS UPON THE NUMBER OF DEGREES OF FREEDOM $/&  &OR ADAPTIVE BEAMFORMING  THE NUMBER OF DEGREES OF FREEDOM IS  .  
 Thereceiver frequency-response function, forpurposes ofthisdiscussion, isassumed to applyfromtheantenna terminals totheoutputoftheIFamplifier. (Theseconddetector and videoportionofthewell-designed radarsuperheterodyne receiverwillhavenegligible efTecton theoutputsignal-to-noise ratioifthereceiver isdesigned asamatched filter.)Narrowbanding ismostconveniently accomplished intheIF.Thebandwidths oftheRFandmixerstagesof thenormalsuperheterodyne receiver areusuallylargecompared withtheIFbandwidth. Therefore thefrequency-response function oftheportionofthereceiver included' between the antenna terminals totheoutputoftheIFamplifier istakentobethatoftheIFamplifier alone. 
 MONOPULSE RADAR ALTIMETER FOR  CONTINENTAL ICE SHEET MONITORING v IN  0ROCEEDINGS  )%%% )NTERNATIONAL 'EOSCIENCE AND 2EMOTE  3ENSING 3YMPOSIUM )'!233g  &LORENCE  )TALY  )%%%    PP n  2 + 2ANEY AND * 2 *ENSEN  h!N !IRBORNE #RYO3AT 0ROTOTYPE 4HE $0 2ADAR !LTIMETER v  IN 0ROCEEDINGS OF THE )NTERNATIONAL 'EOSCIENCE AND 2EMOTE 3ENSING  3YMPOSIUM )'!233   4ORONTO  )%%%    PP n  3 ,AXON  . 0EACOCK  AND $ 3MITH  h(IGH INTERANNUAL VARIABILITY OF SEA ICE THICKNESS IN THE  !RCTIC REGION v ,ETTERS TO .ATURE  VOL   PP n  . £n°Èn  2!$!2 (!.$"//+    ! * "UTRICA   4O  3EE  THE  5NSEEN !  (ISTORY  OF  0LANETARY  2ADAR   $ARBY  0! $IANE  0UBLICATIONS     3 * /STRO  h0LANETARY RADAR ASTRONOMY v IN  4HE  %NCYCLOPEDIA  OF  0HYSICAL  3CIENCE  AND  4ECHNOLOGY  RD %DITION  2 ! -EYERS ED   3AN $IEGO  !CADEMIC 0RESS    PP n   $ " #AMPBELL  2 3 (UDSON  AND * 
 Bombing B. Underwater mobile,  submarineP. Radar D. 
 However, for purposes of analysis, most fluctuating clutter targets may be represented by a  model consisting of many independent scatterers located within the resolution cell of the radar.  The echo at the radar receiver is the vector sum of the echo signals received from each of the  individual scatters; that is, the relative phase as well as the amplitude from each scatterer  innuences the resultant composite signal. If the individual scatters remain fixed from pulse to  pulse, the resultant echo signal will also remain fixed. 
 TEMS ARE GENERALLY COVERED BY MANY LOW 
 vol. IT-14, pp. 734 -743. 
 Kay, Modern Spectral Estimation: Theory and Application,  New York: Prentice-Hall, 1988. 106. S. 
 Reggia-Spencer phase shifters, other novel ferrite phaser configurations, and ferrite micro­ wave integrated components.)  34. Di Bartolo, J., W. J. 
 ROUGHENED OCEANIC SURFACE DEPENDS FOREMOST ON THE RADARS WAVELENGTH  THE LOCAL ANGLE OF INCIDENCE  AND THE POLARIZATION  RESPECTIVELY 4HE WIND PARA METERS TO BE ESTIMATED  ARE ITS SPEED  THE RELATIVE ANGLE IN THE HORIZONTAL PLANE BETWEEN THE WIND DIRECTION  AND THE RADAR LINE 
 FREQUENCY APPROXIMATIONS DEVELOPED FOR THE 2AYLEIGH REGION CAN EXTEND UPWARD INTO THE RESONANCE REGION %XACT -ETHODS  4HE EXACT METHODS ARE BASED ON EITHER THE INTEGRAL OR DIFFEREN 
 Element-Phasing Calculations. A computer is usually required to perform the steering computations for a phased array antenna. It can compensate for many of the known phase errors caused by the microwave components, the operating environment, and the physical placement of the elements. 
 E  (l}  w 100 ·- Vl  0  C  0  C  ~ 50 - C  <! Asymptote  O~~~~~~~~~~~~~  -10 IJ +10 +20  Antenna elevation angle, deg PROPAGATION OF RADAR WAVES 465  Figure 12.13 Computed antenna noise-temperature as a  function of elevation angle for a 10-ft-diameter (3 m)  parabolic-reflector antenna operating at a frequency of  I GHz. (After Greene,61 courtesy Airborne lnstrumems  Laboratory.)  the sea, (3) the antenna always pointing at the galactic center (4) no intense radio stars in the  antenna pattern, (5) resistive losses in the reflector, feed, and transmission line absorbing 2  percent of the incident power, and (6) the feed producing a parabolic illumination taper.  12.9 MICROWAVE-RADIATION HAZARDS  High power microwave energy can produce spectacular effects. 
  
   -%4%/2/,/')#!, 2!$!2   £°Î -EISCHNERS  7EATHER 2ADAR PROVIDE AN EVOLVING PERSPECTIVE ON MANY ASPECTS OF METEO 
 Compressed pulse Wavy sea surf ace (SWH2) Sea surf ace (flat) Wavy sea surf ace (SWH1) Waveform powerMean noise level Track point tTTime dela y (Range bins) Range windo w(a) (b) SWH1 SWH2Flat ch18.indd   32 12/19/07   5:14:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 Since the pulse doppler receiver is basically a spectral analyzer, the radar requirements are most readily defined in terms of the allowable level of these modulation sidebands. The predominant effect of these sidebands depends on the sideband fre- quency. For sideband frequencies greater than/min, the sidebands on clutter sig- nals fall outside the clutter rejection filter, where /min is the minimum frequency separation of a detection filter from the edge of the main-beam clutter. 
 DAY AT A MID 
 SIDELOBES WITH THE NONLINEAR &- WAVEFORM WERE  D" BELOW THE PEAK RESPONSE )T MIGHT BE NOTED THAT #OLE ET AL  STATE THAT IN ORDER hTO ENSURE CONTINUED AVAILABILITY OF THE POWER TRANSISTORS  REQUIRED TO PRODUCE THE POWER AMPLIFIER PANELS  .ORTHROP 'RUMMAN HAS DEVELOPED AN IN 
 The directivity of the antenna in  the transmission and reception phases allows space discrimination to be used as an  ECCM strategy. Techniques for space discrimination include antenna coverage and  scan control, reduction of main-beam width, low sidelobes, sidelobe blanking, side- lobe cancelers, and adaptive array systems. Some of these techniques are useful dur - ing transmission, whereas others operate in the reception phase. 
 The first five effects are usually included in the pattern propagation and loss factor terms of Eq. (25.1). The geometry effect is treated separately. 
 The  high end of the frequency band is limited by the physical size of the elements,  which must be spaced close enough in the array to avoid the generation of grating  lobes (see Section 13.2). For wide instantaneous bandwidth (rather than tunable  bandwidth), time delays have to be added to prevent the beam from being scanned  as the frequency is changed. The impedance of the radiating element at the aperture (with closely spaced  elements) is approximately independent of frequency, but the element must be  matched over the wide bandwidth. 
 5.8] F-M RANGE-MEASURING SYSTEM 145 (7) ‘I’his isofthe nature ofamaximum error and can bemuch reduced byaveraging over anumber ofmodulation cycles. Design Procedure. —Design ofsuch analtimeter isbegun byusing theabove equation, together with anallowable altitude error, topick a suitable Af. 
 Whatever their sourc+and this may range from apassing trolley car tothe mysterious reaches ofinterstellar spat-these disturbances enter the receiver byway ofthe antenna. The crucial quantity istherefore the ratio ofthe field strength ofthe signal intheneighborhood oftheantenna tothat ofnoise orinterference.. SEC.2.7] NOISE 29 The absolute magnitudes ofsignal and interference power available attheantenna terminals areoflittle importance; only their ratio, which, forexample, might befavorably altered bythe use ofadirectional antenna pattern, determines the ultimate performance. 
 ERWISE  THE SKIN ECHO WILL OVERWHELM THE JAMMING SIGNALS IN THE INTERFEROMETER PATTERN NULLS 4HE MAXIMUM EFFECTIVENESS OF THE TECHNIQUE IMPLIES A CONSIDERABLE DELAY ON THE ORDER OF  NS  IN THE REPEATED SIGNAL  OWING TO THE TRANSMISSION LINE AND AMPLIFIER BETWEEN THE RECEIVER AND TRANSMITTER ANTENNAS 4HUS  LEADING 
 Radar modulation transfer function,” J. Geophys.  Res., vol. 
 However, when the path length introduced by the dielectric is equal to a  wavelength. the path in the dielectric can be reduced to zero without altering the phase across  the aperture. The thickness of the lens is again increased in the direction of the axis according  to the leris design until the path length in the dielectric is once more 360°, at which time  another step may be made. 
 Remote Sens. 2016 ,54, 4732–4748. [ CrossRef ] 13. 
 With these substitutions, 5min becomes ^0Fn(E/N0)h. Substituting into Eq. (1.2) gives . 
 NIQUES  THE USE OF PHASE SHIFTERS IS BY FAR THE MOST POPULAR  AND CONSIDERABLE EFFORT HAS GONE INTO THE DEVELOPMENT OF A VARIETY OF PHASE SHIFTERS 0HASE SHIFTERS CAN BE SEPA 
 Othermethods thathavebeenproposeq forcompensating theclutterdopplershiftseen byamovingradarincludethe"matrixMTI"60forimplementation indigitalMTI,anda "trialanderror" tech~iques9.68 thatprovides simultaneously anumberofpossibledoppler corrections andusesthatonewhichproduces theminimum residueoverthesampled range interval. Stillanother technique thatisattractive whenitcanbeapplied, istouseadoppler processor witharejection notchwideenoughtorejecttheclutterdopplerevenwhentheradar platform isinmotion.Thisisapplicable onlywhenthefirstblindspeedishigh(alowradar frequency and/orhighprf)andwhentheplatform speedislow,asitwouldbewithaship­ mounted radar. Generally, mostclutter-lock MTItechniques' donotadequately eliminate bothstationary andmovingclutterwhentheyappearsimultaneously withinthesamerangeresolution cell.A TACCAR, forexample, mightbedesigned torejectgroundclutterclosein,andweatheror chaffatadifferent doppleratrangesbeyondthegroundclutter;butnottocanceltwodifferent clutterdopplerfrequencies simultaneously.8 Anexception istheadaptive MTI62.6swhichcan adapttoanytypeofclutter.Usingtechnology similartothatoftheantennasidelobe canceler, nullsareadaptively placedatthosefrequencies containing largeclutter.Athree-loop adaptive canceler, forexample, canadaptively placethreenullsatthreedifferent frequencies oritcan placethethreenullssoastomakeasinglewidenotch,depending onthenatureoftheclutter spectrum. 
 G .. A. P. 
 and R. A. Handy: Progress in Helix Traveling-wave Tubes ror Radar Systems, Microwm•e  System News. 
 Inthecase ofseaand storm echoes, there isnofixed component. TABLE 162.-Typical, nlEASCRED VALUES OFC;LUTTEE FLUCTUATION Kind ofclutter I IThunderstorm. Sea echo ............... 
 Syst. 1996 ,32, 1185–1191. [ CrossRef ] 21. 
 Although the signal processing required is similar to that of thdconventional  synthetic aperture radar, the inverse synthetic aperture process can also be viewed as an  equivalent doppler filtering. Each part of a moving target has a slightly different relative  velocity, or doppler-frequency shift. Filtering thcse varioils dopplcr frequencies resolves the f  different parts of the target to provide an image. 
 COVERED SURFACES SCATTER ESSENTIALLY UNIFORMLY EXCEPT FOR THE EFFECTS OF THE MULTIPATH FADING 3EA )CE 3EA ICE IS A VERY COMPLEX MEDIUM )CE OBSERVERS CHARACTERIZE IT IN  MANY DIFFERENT CATEGORIES THAT DEPEND ON THICKNESS  AGE  AND HISTORY OF FORMATION   (ENCE  ONE CANNOT CHARACTERIZE ITS RADAR RETURN IN ANY SIMPLE WAY IN THIS SENSE  IT IS LIKE VEGETATION 4HE MOST IMPORTANT ICE TYPES FROM A RADAR POINT OF VIEW ARE FIRST 
 Asarange reduction of10per cent is considered themaximum allowable, itcan beseen that thebeam must be stabilized sothat itremains within 0.28 beamwidt hofacompletely stabilized position. The adequacy ofthe above calculations has been verified byrough observations inflight. Beam stabilization incurrent airborne navigation radars should beaccurate within about t1.3°, depending ontheset, lest range performance suffer noticeably. 
 Therefore, as a compromise between the requirements for  accurate range and angle tracking, a crossover nearer the peak of the beam is usually selected  rather than that indicated from Fig. 5.6. It has been-suggested that the compromise value of  0,/08 be abbut 0.28, corresponding to a point on the antenna pattern about 1.0 dB below the  peak.1.2  Other considerations. 
 Among thelatter aresuch appli- cations asthe intensifying ofcathode-ray tubes and the operating of various electronic switches. Rectangular waves can beused fortiming purposes—for example, toinitiate thegeneration ofsharp pulses orother- wise toinitiate some particular event attheinstant ofoccurrence ofone ofthewavefronts. The circuits that produce such waveforms can bedivided into three categories: 1.Those inwhich the waveform isproduced without external stimulus—that is,free-running oscillators (Fig. 
 Consequently, although they are extremely. SEC. 13.211 SPECIAL RECEIVING TECHNIQUES 551 ( ( I. 
 The choice between using switched  or tunable filtering depends on the switching speed, linearity, and stability requirements of  the receiver. Switched filters provide the fastest response time, with excellent linearity and  stability but can be bulky and suffer from the additional loss of the switch components. An alternate approach that is sometimes used with large operating bandwidths is  to first upconvert the input RF signal to an IF frequency higher than the RF operating  band. 
 7.51  Broad Instantaneous Bandwidth  .........................  7.53  Time-Delay Networks  ........................................  7.56  7.8 Feed Networks (Beam formers)  .............................. 
 30.Golomb, S.W.:"DigitalCommunications withSpaceApplications," Prentice-Hall, Englewood Cliffs, N.J..1964. 3\.Ackroyd, M.H.,andF.Ghani:Optimum Mismatch FiltersforSidelobe Suppression, IEEETrans., vol.AES-9,pp.214-218. March.1971 32.Millett,R.E.:AMatched-Filter Pulse-Compression SystemUsingaNonlinear FMWaveform, IEEE Trans.,vol.AES-6.pp.73-78,January, 1970. 
 HORIZON  SEARCH  AND FIRE CONTROL TRACK AND ILLUMINATION /NE OF THE MOST SIGNIFICANT DESIGN FEATURES OF THE RADAR IS TO PROVIDE AUTOMATIC DETECTION  TRACKING  AND ILLUMINATION OF LOW 
 The J-dB ha11dwidth is defined as the separation in hertz between the points 011 the  frequency-response characteristic where the response is reduced to 0.707 (3 dB) from its maxi­ mum value. The J-d B bandwidth is widely used. since it is easy lo measure. 
 1966. 105.Hardy, K.R.,andI.Katz:Probing theClearAtmosphere withHighPower.HighResolution Radars,Proc.IEEE.vol.57.pp.468-480. April,1969. 
 Sound system-design work, together with performance tests, can serve inavaluable way todirect component-development work along themost advantageous lines. Detailed Problems inDesign. —General rules forguidance onthemany detailed problems encountered inthe development ofaradar system would beextremely difficult toformulate because ofthe multiplicity of applications with radically differing requirements. 
 Many studies concerning the design of satellite constellations for optimal cov- erage have been made and reported. ~28 Luders and Ginsberg24 describe an an- alytical solution to the problem of achieving continuous coverage of latitudinally TABLE 22.2 Selected Orbital Parameters Altitude, nmi 99 414 912 2,262 5,612 19,369Velocity, ft/s 25,587 24,520 23,074 20,157 15,999 10,079Period, min 88 100 120 180 360 1,440 . bounded zones of the globe. 
 At ranges far beyond the horizon, the propagation loss  is dominated by troposcatter. Propagation in the troposcatter region is the result of  scattering by small inhomogeneities within the atmosphere’s refractive structure. At  radar frequencies, troposcatter is generally not considered for radar range perfor - mance. 
 FIGURE 12.3  Capacitive loading to reduce feed horn blockage ch12.indd   8 12/17/07   2:31:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 
 * *!&%)    +%*!&%&(   ( ) &# *    !#* (  !  *!%   '+(  , 
 The strength-to-weight ratio of the A sandwich is greater  than that of a solid-wall radome. It is also capable of broader bandwidth. However, it is more  sensitive to variations in polarization and angle of incidence. 
 Areasonable compromise istomakethe gatewidthoftheorderofthepulsewidth. /\targetoffinitelengthcancausenoiseinrange-tracking circuitsinananalogous manner toangle-fluctuation noise(glint)intheangle-tracking circuits. Range-tracking noisedepends onthelengthofthetargetanditsshare.Ithasbeenreported29thatthermsvalueoftherange noiseisapproximately 0.8ofthetargetlengthwhentracking isaccomplished withavideo split-range-gate errordetector. 
 Therefore, under the premise of ensuring the resolution of the system, ArcSAR can cover the 360-degree scenes in once scanning, which e ﬀectively improve the ﬁeld of view. Currently, several teams are working on the ArcSAR system [ 12–20], and the imaging algorithms for ArcSAR are also proposed. Lee et al. 
 Onreception, aseparate receive beammustbegenerated foreachdirection oftransmission. Inasurveillance application this couldrequirethecomplication ofsomesortofbeam-forming. Inatracking phased-array radar,however, asingletime-shared receivebeamcanbeusedsimultaneously totrackmany targetsatdifferent angular directions. 
  
 A multiple-bit diode phase shifter need not be constructed with all of the  same types of phase bits. The loaded-line circuit is often preferred for small phase increments  because of its compact size. It is not as suitable for large phase steps because it is difficult to  match in both states under this condition. 
 714–719. ch24.indd   63 12/19/07   6:01:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Both these effects can result in  target losses.  If a summing process (with div ision by 2) replaces the MAX -process of the  CAGO- CFAR, then the CAGO -CFAR results in the so -called C ell Averaging CA- CFAR. Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  115     LL/2+3 L/2+2 L/2+1 CUTL/2 321samples of the digital signalSUT-TVtarget identification +β ·αSUT TVs t r o a ge . 
 AP-9,  pp. 154- 161, Mirch, 1961.  87. 
 DigitalfilterbanksandtheFIT.Atransversal filterwithNoutputs(NpulsesandN-1 delaylines)canbemadetoformabankofNcontiguous filterscovering thefrequency range from0tofp,wherefp=pulserepetition frequency. Afilterbankcovering thedoppler frequency rangeisofadvantage insomeradarapplications andoffersanotheroptioninthe designofMTIsignalprocessors. Consider thetransversal filterthatwasshowninFig.4.11to haveN-IdelaylineseachwithadelaytimeT=l/fp'Lettheweightsappliedtotheoutputs oftheNtapsbe: W-e-J12n(i-l)It{N) fit- (4.13). 
 TARGET RETURNS TEND TO FLUCTUATE FROM SCAN TO SCAN WITH FI XED 
 In addition, it should be noted that the purpose of analyzing DEM accuracy and deformation monitoring accuracy is to demonstrate the e ﬀect of DEM assist on improving the accuracy of the results. In practice, the analysis of DEM accuracy and deformation monitoring accuracy also needs to consider more complex factors such as baseline decoherence and time decoherence. Since these factors are not relevant to our topic, they are not considered in this paper. 
 TO 
 -(Z BAND 
 J. Remote Sens. 2016 ,37, 2394–2414. 
 L.: The Design of Radially Symmetric Lenses, IEEE Trans .• vol. AP-18, pp. 497-506. 
 ILLUMINATED PRECIPITATION IS RELA 
 MIT AND RECEIVE TO DETECT THE TARGET 4HE DIFFERENCE BEAM IS RECEIVE ONLY AND PROVIDES ANGLE DETERMINATION )N MOST APPLICATIONS  BOTH AZIMUTH AND ELEVATION DIFFERENCE BEAM PORTS ARE IMPLEMENTED &IGURE  ILLUSTRATES THE CONCEPT OF  AMPLITUDE COMPARI 
 E. Nathanson3) ch15.indd   10 12/15/07   6:16:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 POWER WAVEFORMS 4HE  LIMITATION ON PEAK POWER IN  A SOLID 
 Purduski114 © IEEE 1980 ) Time of   Day PolarizationFrequency  Range, GHzConstant   A, dBAngle Slope  B, dB/ °Frequency  Slope C,  dB/GHzSlope Correction  D, dB/   (° × GHz) Day V 1–8 −10.0 −0.29   0.052  0.022 Day V 13–17  0.02 −0.37  −0.50  0.021 Day H 1–8 −11.9 −0.25   0.55  0.012 Day H 13–17  −6.6 −0.31   0.0011  0.013 Night V 1–8 −10.0 −0.33 −0.32  0.033 Night V 13–17 −10.9 −0.13   0.70  0.00050 Night H 1–8 −10.5 −0.30   0.20  0.027 Night H 13–17 −16.9 −0.024   1.036 –0.0069 * After R. K. Moore, K. 
 185. G. A. 
 42 
 FIELD DISTRIBUTION FOR SUM AND DIFFERENCE SIGNALS.   42!#+).' 2!$!2   °Ç ! PRACTICAL APPROACH TO MONOPULSE FEED DESIGN USES HIGHER 
 Doppler processing is essential under such conditions.  For some aircraft, the radar cross section at HF is significantly larger than that at micro - waves. Many HF OTH radars utilize an FM-CW waveform, so widely separated sites are  needed to minimize the leakage of the transmitter into the receiver. 
 1972.  27. 1-aylor. 
 TIONAL SKYWAVE RADAR DETECTIONS. Óä°£n  2!$!2 (!.$"//+  $AYTIME ABSORPTION INCREASES FOR A GIVEN FREQUENCY BECAUSE OF HIGHER $ 
 C. Douglas, “Seasonal comparisons of sea ice concentration estimates  derived from SSM/I, OKEAN, and RADARSAT data,” Rem. Sens. 
 L.,andG.E.Uhlenbeck (eds.):"Threshold Signals," MITRadiation Laboratory Series, vol.24,sec.7.5,McGraw-Hili BookCompany, NewYork,1950. 32.Middleton, D.:Statistical TheoryofSignalDetection, IRETrans.,no.PGIT-3, pp.26-51,March, 1954. 33.VanMeter,D.,andD.Middleton: Modern Statistical Approaches toReception inCommunication Theory,IRETrans.,no.PGIT-4, pp.119-141, September, 1954. 
 D. Queen,19 Naval Research Laboratory.) more explicit detail than this should consult referenced material at the end of this chapter. 77.3 RCSPREDICTIONTECHNIQUES Although the complexity and size of most scattering objects preclude the appli- cation of exact methods of radar cross-section prediction, exact solutions for sim- ple bodies provide valuable checks for approximate methods. 
 14 through 17. ISAR. Inverse synthetic aperture radar (ISAR) is the term used when the motion of the object being imaged is used instead of the motion of the radar. 
 SUITED FOR THIS APPLICATION £ä°{Ê  ,"-- 
 A simplified approximate  model of propagation in atmospheric ducts gives the maximum wavelength·that can be pro­ pagated in a surface duct uf depth d as28  ( 6n) 112 A.mu= 2.5 -6h J3/2 (12.13)  where Amu• 6/1, and dare in the same units. For example, at X band P-max = 3 cm)1 Eq. (12.13)  predicts that the duct must be at least 10 m thick; at S band (,l = 10 cm) it must be 22 m; and  at UHF (,l = 70 cm), the duct thickness must be at least 80 m thick. 
 Kalmus, H. P.: Doppler Wave Recognition with High Clutter Rejection, IEEE Trans., vol. AES-3,  no. 
 4O 
 ABILITY DENSITY FUNCTION 4HERMAL NOISE IS ALWAYS PRESENT IN THE RADAR RECEIVER AND IS THE ULTIMATE LIMIT ON RADAR SENSITIVITY 4HE ABSOLUTE LEVEL OF ADDITIVE NOISE SOURCES IS DETERMINED BY THE SOURCE AND ITS RELATION TO THE RADAR 0ROPER SYSTEM DESIGN CAN REDUCE THERMAL NOISE TO A LEVEL WHERE MULTIPLICATIVE NOISE CAN BECOME SIGNIFICANT IN LIMITING THE RADAR SENSITIVITY -ULTIPLICATIVE NOISE IS CHARACTERIZED BY EITHER A TIME 
 SCAN ERROR SLOPE  KS    FOR SYSTEM OPTIMUM   P"   ONE 
 The thickness of the various layers of a road can be measured using GPR techniques  as shown in Figure 21.25. The great advantage is that this method is nondestructive  and high speed (>40 km/hr) and can be applied dynamically to achieve a continuous  profile or rolling map. The accuracy of calibration tends to reduce as a function of FIGURE 21.32  Example of GPR image of TMA3 AT mine ( Courtesy IEE ) FIGURE 21.33  Example of AT mine images taken over a 4 m by 20 m test site with the MINDER GPR  radar system ( Courtesy IEE ) ch21.indd   37 12/17/07   2:51:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 These televisions used a tuned radio frequency (TRF) receiver on the broadcast frequency of 45 Mc/s and this choice of IF seems to have beencontinued in subsequent designs . TR.3519 included an IF head ampli ﬁer, type 2 3 A ,w h i c hw a sg a i nc o n t r o l l e di ns y n chronism with the receiver R3553 or R3554. The TR switch was improved and was installed in waveguide, using a soft rhumbatron tube, CV179. 
 For our purposes, the image of the target is extracted manually in this paper. The aspect entropy can be obtained using the same method described in subsection A. After thresholding according to the aspect entropy value, we can obtain a binary image. 
 a condition opposite to that desired.  An examination of the Bessel functions (Fig. 3.16) shows that if one of the modulation­ frequency harmonics is extracted (such as the first, second, or third harmonic), the amplitude  of the leakage signal at zero range may theoretically be made equal to zero. 
 COMBINING CIRCUIT TOPOLOGIES THAT ARE USED TO PROVIDE  ISOLATION AMONG ADJACENT PARALLEL AMPLIFIERS IN A CORPORATE COMBINING STRUCTURE &)'52%   #ONTOURS OF POWER LOST TO THE ISOLATION LOAD RESISTOR OF AN ISOLATED POWER COM 
 POLARIZED ANTENNA ELEMENTS  2)3!4 HAS FIVE MODES  EACH OF WHICH MAY OPERATE AT A VARIETY OF INCIDENT ANGLES 4HE MODES ARE FINE 
 Ender, “Anti-jamming adaptive filtering for SAR imaging,” Proc. of IRS ’98 , Int. Radar  Symp ., Munich, Germany, September 15–17, 1998, pp. 
 (In terms of the Stokes parameters, S2 = 0). The H and V backscatter coefficients  will always be equivalent when the radar’s illumination is perpendicular to the surface.  Hence, any hybrid-polarity radar can set up this condition by the simple expedient of  looking down on a horizontal surface during a calibration exercise. 
 13.21), in which gain and limit level are electronically switched back and forth from levels most suitable forland-water contrast tolevels giving the. 102 PROPERTIES OF RADAR TARGETS [SEC. 316 best overland contrast for the brightest target highlights. 
 In addition, amplitude fluctuations in the RF drive will also  cause drive-induced jitter, which may even exceed power-supply-ripple-induced jitter,  so this factor must be carefully measured. Spectral Emissions.  When a rectangular RF drive pulse is applied to a single  module, the amplifier will typically show rise and fall times that are on the order  of nanoseconds. 
 sea  echo is more uniform over the oceans of the world. providing the wind conditions arc the  same. Although knowledge of sea clutter is far from complete, it is better understood than is  the knowledge of land clutter. 
 R.: "Introduction to Monopulse," McGraw-Hill Book Company, New York, 1959; reprinted by Artech House, Norwood, Mass., 1982. 38. Kinsey, R. 
 This is an important aspect of  the detection process since the initiation of a track after a new target is detected requires a  setlirence of radar dwells that can consume the resources of the radar and the computer.  .flit rrcic,k-irliricitior~ process after a new detection has been established is a demanding one.  The radar riiust observe the target a significant number of times within a modest time interval  to cli~ickly establish the target's direction of travel and speed. 
 RELATED  PATENT APPLICATIONS CONTINUE APACE )N SHORT  3"2  IS AN EXCITING  EXACTING  EXTENSIVE  AND EXPANDING TOPIC 3PACE 
 J. Kappl, and N. E. 
 TO 
 Onepotential application ofadaptive a'rrayantennas isforairborne surveillance radal. Inaddition tothereduction ofjamming noisewhichentertheairborne surveillance radar, itisimportant toreducetheclutterthatentersviatheradarantenna sidelobes. Thedetection oftargetsfromanairhorne platform placesseveredemands onradardesigninordertoreduce oreliminate clutterthatenterstheradarreceiver viathemainbeam.Thisisdoneina conventional AMTIradarbysignalprocessing (filtering) asdescribed inSec.4.11.However, c1ullerthatenterstheradarreceiver viatheantenna sidelobes hasdoppler frequencies that cannotberejected byconventional filtering, sincetargetsofinterestcanhavethesamedoppler asthesidelobeclutter.Anadaptive arrayantenna canplacenullsinthedirection ofsidelobe clutterbyusingthesidelobe clutteritselfasthesignaltobecancelled. 
 rnaddition, thecomputer provides themeanswhereby anoperator canmanually interact withtheradar, Beam-steering computer. Although asinglegeneral-purpose computer canbeusedtoperform allthecomputations andcontrol required foraphased-array radar,itisoftendesirable to utilizeaseparate, special-purpose computer forbeamsteering. Thiscanbeanintegral partof theradarhardware soastominimize theproblem ofcommunicating thelargenumber of phase-shifter orders.Thegeneral-purpose radar-control computer provides thebeam-steering computer withthedesiredelevation angleandazimuth angle.Thebeam-steering computer translates Ihisintocommands necessary foreachphaseshifter.Insomearraydesigns with frequency-dependent phaseshifters, thefrequency alsomustbesupplied tothebeam-steering computer alongwiththetwoangles. 
 Forcing the jammer to spread power over the entire band available to a radar is generally  not sufficient in itself. The jammer also must be forced to spread its available power over more  than one radar band. This can be accomplished withfreqltency diversity by using two or more  radars. 
 The CF A also resembles the traveling­ wave tube because the electronic interaction in both is with a traveling-wave.  There are several different types of crossed-field amplifiers. They all employ a slow-wave  circuit. 
 PULSE SYSTEM WITH SUM AND DIFFERENCE OUTPUTS AND  B  VECTOR DIAGRAM OF THE SUM AND DIFFERENCE SIGNALS .   42!#+).' 2!$!2   °£Î OF PULSES -ONOPULSE TRACKING IS NECESSARY TO OBTAIN ANGLE DATA ON EACH PULSE TO  MAINTAIN ADEQUATE DATA RATES WHEN SHARING PULSES AND POWER AMONG SEVERAL TARGETS ! DETAILED DISCUSSION OF ELECTRONIC SCAN PHASED ARRAYS IS GIVEN IN #HAPTER  HOWEVER  SOME CHARACTERISTICS OF THE ARRAYS REQUIRE SPECIAL CONSIDERATION FOR THE ANGLE TRACKING PERFORMANCE OF TRACKING RADARS USING MONOPULSE PHASED ARRAY ANTENNAS /PTICAL 
 ACTERISTICS  A MAXIMUM LENGTH SEQUENCE DOES NOT GUARANTEE LOWEST TIME SIDELOBES WHEN COMPARED TO OTHER BINARY CODES !N EXAMPLE OF THIS IS PROVIDED FOR A  
 Inthis chapter, more emphasis isputonthenewer bea- cons athigher frequencies since thetrend inradar istoward microwaves. The beacon isessentially arepeater ofradar pulses. Ithas an antenna and receiver that convert pulses ofenergy, received athigh frequency from aradar setorspecial interrogator, into triggering signals. 
 ingthe spot togrow “wings” whose length issome rough inverse measure ofthe range. Inthis form (Fig. 6.13)the indication gives toasurprising degree theillusion ofanactual aircraft which apparently grows larger asitapproaches. 
 ENT IN THE RADAR BAND SIMULTANEOUSLY 'ENERALLY  THE INTERFERENCE POWER ENTERING    THE !$ CONVERTER IS PROPORTIONAL TO THE BANDWIDTH OF COMPONENTS IN FRONT OF THE .   2!$!2 2%#%)6%23   È°{£ !$ CONVERTER 4HE REQUIRED !$ CONVERTER 3.2 TO AVOID SATURATION ON THE INTERFER 
 6.13. Energy from an  external source is accumulated in the energy-storage element at a slow rate during the inter-  pulse period. The charging impedence limits the rate at which energy can be delivered to the  storage element. 
 This is then substituted into Eq. 3.27:  ˆw R R br s=−1  (3.28) Equation 3.28 is equivalent to the minimum mean square error weight equation  given by Widrow,18 which has been shown19,20 to be the optimum set that maximizes  the signal-to-interference ratio. However, complex variables are employed here rather  than real variables. 
 #  UNTIL %.6)3!4 0!,3!2 )N CONTRAST TO THE INCOHERENT POLARIMETRIC OPTIONS OF !3!2  THE 0HASED 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter.  SEA CLUTTER  15.376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 scattering properties with numerical calculations, and then going to the wave tank  to verify the scattering behavior for real water waves. 
 Method Accuracy (%) Original dataset with simple CNN models 85.71 Original dataset with transfer learning 94.93 When compared the results with Tables 2–8. we can easily ﬁnd that with no data processing in our dataset, the CNNs cannot perform well either using transfer learning or not. The experimental results conﬁrm that both the data processing and the way in CNN training should be concerned to get better performance. 
 Figure8.I5isaplotofthebeamdirection asafunction ofthefrequency forvarious valuesofthe~'wrap-up fqcto,'l/d, asgivenbyEq.(8.18).Notethatthebeamposition isnot symmetrical withfrequency. Toscanthebeam±45°aboutbroadside requires abandwidth of almost30percent withawrap-up factorof5,and7percent forawrap-up factorof20. (Percentage bandwidth =100~f/fo.) Afrequency-scan radarrequires aconsiderable portionoftheavailable bandofaradart,o~"""'~ bedevoted tobeamsteering. 
 VIIASV Mk. VIASV Mk. VII 5000 6 –18 5 –12 3 –6 3000 5 –14 6 –12 5 –93 –5 2000 6 –12 5 –11 5 –82 –4 1500 5 –9 1000 5 –97 –11 3 –74 –62 –32 –3 500 5 –84 –72 –53 –51 –22 200 3 –5 100 3 1 –2Airborne Maritime Surveillance Radar, Volume 1 7-5. 
 TIME DATA PROCESSING  AS IN TARGET TRACKING AND DISPLAY PROCESSING 3INCE THE S  THEY HAVE STARTED TO BE APPLIED TO REAL 
 ≥ aA rank-selection r with amplitude ar   Figure 12.3  Principle of the OS -CFAR circuit.   The OS- CFAR (O rdered Statistic) comprises a shift register containing “A” storage cells, plus  the CUT. A sorting algorithm arranges the amplitudes of th e storage cells in o rder of decrea s- ing magnitude. 
 Soc., vol. A 109. p. 
 Tasks which are not as time critical should  be deferred so that high-priority tasks can be accomplished. Table 8.2 is an example of  a priority structure for a tactical air defense system in which the radar performs search  and automatic tracking, as well as support missile engagements. 121 There are eight categories  of priority, from the dedicated mode with the highest priority, to the standard testing and  dummy operations (or time wasters) with the lowest priority. 
 ERROR SOURCES AND THEIR MAGNITUDE ARE GIVE IN 3ECTION  OF "ARTON  ,IMITATIONS OF 0ERFORMANCE  -ITCHELL ET AL DESCRIBE BASIC PERFORMANCE  LIMITATIONS OF THE !.&01 
 Although they may occur in-  frequently, they can be quite large and give undue weight in a conventional integrator. In the  double-threshold detector they contribute the same as any threshold-crossing signal no matter  what their amplitude. An analysis of the problem of detection of signals in clutter (or noise)  that is nongaussian, indicates that a detector based on the median value crossing a threshold is  significantly more efficient than the usual detection criterion based on the nterin value.61 The  implementation of the binary moving window detector is similar to that of the median  detector. 
 An example of a received clutter spectrum given an antenna response is shown  in Figure 3.6 a. The TACCAR frequency offset then shifts main-beam clutter to zero  doppler, as shown in Figure 3.6 b. FIGURE 3. 
 Whenthesystemrequirements permitatimesharingofthedoppler frequency range,thebankofdoppler filtersmaybereplaced byasinglenarrowband tunablefilterwhich searches infrequency overthebandofexpected doppler frequencies untilasignalisfound.. After detecting and recognizing the signal, the filter may be programmed to continue its search  in frequency for additional signals. One of the techniques for accomplishing this is similar to  the tracking speed-gate mentioned in Sec. 
 This isnot tooserious inthecase ofthe movable range marker, because itappears atallazimuths andcanbe’6steered” intheproper direction asitapproaches theper- sistent echo remaining from the previous scan. Anangle index, onthe other hand, ifformed bythemethods of),1 1 Data transmitter Display @wcircuits * Operator’s control FIG.13.35.—Substitution method for movable angle index. thepreceding paragraph will “flash up” only asthe scanner passes by. 
 RADAR MODULATION TRANSFER FUNCTION v * 'EOPHYS 2ES  VOL   PP n    " ,E-EHAUTE AND 4 +HANGAONKAR  h$YNAMIC INTERACTION OF INTENSE RAIN WITH WATER WAVES v   * 0HYS /CEANOG  VOL   $ECEMBER   , " 7ETZEL  h/N THE ORIGIN OF LONG 
 Note  318, August 5, 1965. 108. D. 
 RONMENT   BUT DOES NOT HAVE THE MAXIMUM DETECTION RANGE PROVIDED BY THE HIGHER DUTY CYCLE OF (273 FOR THERMAL NOISE 
 The S/N is the value at the center of the beam. ( after P . Swerling6 © IEEE 1956 ) ch07.indd   4 12/17/07   2:12:53 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 DOMAIN RETURNS IN A SINGLE #0)  THE RESULTING FREQUENCY SIDELOBES CAN BE READILY CONTROLLED &URTHER  THE NUMBER OF FILTERS EQUAL TO THE ORDER OF THE TRANSFORM  NEEDED TO COVER THE TOTAL DOPPLER SPACE EQUAL TO THE RADAR 02&  CAN BE CHOSEN INDEPENDENTLY OF THE #0)  AS DISCUSSED BELOW !S THE #0) BECOMES SMALLER a    IT BECOMES IMPORTANT TO CONSIDER SPECIAL  DESIGNS OF THE INDIVIDUAL FILTERS TO MATCH THE SPECIFIC CLUTTER SUPPRESSION REQUIREMENTS AT DIFFERENT DOPPLER FREQUENCIES IN  ORDER TO ACHIEVE BETTER OVERALL PERFORMANCE 7HILE  SOME SYSTEMATIC PROCEDURES ARE AVAILABLE FOR DESIGNING &)2 FILTERS SUBJECT TO SPECIFIC PASSBAND AND STOPBAND CONSTRAINTS  THE STRAIGHTFORWARD APPROACH FOR SMALL #0)S IS TO USE AN EMPIRICAL APPROACH IN WHICH THE ZEROS OF EACH FILTER ARE ADJUSTED UNTIL THE DESIRED RESPONSE IS OBTAINED !N EXAMPLE OF SUCH FILTER DESIGNS IS PRESENTED NEXT %MPIRICAL &ILTER $ESIGN   !N EXAMPLE OF AN EMPIRICAL FILTER DESIGN FOR A SIX 
 MENTS IS THAT THE TEST OBJECT BE ILLUMINATED BY A RADAR WAVE OF ACCEPTABLY UNIFORM AMPLITUDE AND PHASE 'OOD PRACTICE DICTATES THAT THE AMPLITUDE OF THE INCIDENT WAVE DEVIATE BY NO MORE  THAN  D" OVER  THE TRANSVERSE AND LONGITUD INAL EXTENT OF THE TAR 
 BASED  NEAR 
 13.9) does allow a grating-lobe peak to occur at  90° when scanning to q0. Even though the grating lobe is reduced when multiplied  by the element pattern, it may be prudent to space the elements such that the first null  of the grating lobe, rather than the peak, occurs at 90 °. With N elements this more  restrictive condition is given by  s N N λ<−×+1 1 10 | sin |q (13.11) Equation 13.8 may again be approximated by the Fourier transform of the illumina - tion across the continuous aperture:  Ea a( ) ( c os)sin ( /)(sin sin ) ( / )(q qq q= +−1201π λ π λ s sin s in ) q q−0 (13.12) The Fourier-transform solutions for continuous apertures19,41 may be used to  approximate patterns for practical amplitude and phase distributions as long as the  element-to-element spacing is small enough to suppress grating lobes.42 Monopulse  difference patterns may be approximated in the same way from the Fourier transforms  of the corresponding continuous odd aperture distributions. 
   PP n   /CTOBER   % $ 3HARP v 4RIANGULAR ARRANGEMENT OF PLANAR 
 Inthe region ofturbulent flow directly under the blower output thetransfer coefficient ishigh. Inthe second case, b,there isanouter shell close tothe wall ofthe pressure container. Apowerful blower maintains turbulent flow over thewhole interspace and ahigh coefficient results. 
 Over a range of errors of approximately ± 1/4 of the target-video  pulse width, the voltage output is essentially a linear function of timing error and  of a polarity corresponding to the direction of error. During acquisition, the target  is centered in the 1000 yd acquisition gate by range-tracking techniques described  as follows, and the gate is reduced to approximately the width of the radar transmit  pulse for normal tracking. Many radar range-tracking systems use high speed sampling circuitry to take three  to five samples in the vicinity of the echo video pulse. 
 NOISE RATIO FOR THE CELL 
 22.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 Racons.  The International Association of Marine Aids to Navigation and  Lighthouse Authorities (IALA) sets the performance standards for racons.30 These  incorporate the technical characteristics set out in a specific ITU-R Recommendation.31  Because racons normally form only one subsystem of an AtoN. they therefore need to  be small in size and power efficient since they are rarely connected to a main power  supply. 
 Ocherangelechoes.Ithasbeensuggested thatotherformsofmeteorological angelsarethe mantle-shaped echoes(inverted U-orV-shape)associated withtheuppersurfaces ofcu­ mulusclouds,andechoesbelieved tobeproduced bytheboundary surfacesbetweendifferen­ tiallymoistened surfaceairoveradjacent coldandwarmwater. 113Radaralsocandetectthe passageofaninvisible seabreezeasitmovestowardtheshore.70.100 Occasionally radar echoesmaybeobtained rromlargemineralororganicparticles carriedintotheairbyheavy windsorthunderstorms.looEchoeshavealsobeenreceived fromthevicinityofrorestfiresand fromthesmokeplumesordumpfires.loaThereflectivity ofsmokeparticles istoosmallto accountforthesereflections, buttheechoesmightbeduetothenumerous largeparticles and debrissometimes presentintheairabovethefires.Theheatfromthefirealsomightcause. atmospheric turbulence which is detectable by radar. 
 Thus a three-PRF system using the seventh, eighth, and ninth submultiples of the range-gate clock frequency fc = \hs as PRFs yields an unambiguous range of 7 x 9 = 63 times that of the middle PRF alone. TABLE 17.4 Multiple-PRF Ranging Parameters NOTE: /W1, W2, m3 must be relatively prime integers. T, = transmitted pulsewidth Tg = range-gate width T6 = blanking width due to receiver recovery TJ = range-gate spacing fc = range-gate clock = Ihs Figure 17.16 shows the maximum unambiguous range as a function of the min- imum PRF,y^min, and the ranging parameter W1, for the case where W1, W2, m3 are consecutive integers. 
 5.4. The sum pattern is used 0:1 transmit  and both the sum and the difference patterns are extracted on receive. The signal received on  the difference pattern is weighted by the factor k, shifted in phase by 90° and is added to the  sum-pattern signal in the delayed channel and subtracted from the sum-pattern signal in the  undelayed channel. 
 Y . I. Abramovich, N. 
 The coefﬁcient must then be closely related to both the geometrical properties of the SAR acquisition and the characteristics of the transmitted chirp. This consideration will be illustrated in the next paragraph. Basing on these observations, a simple and direct scheme to obtain a good focusing of the raw data in a blind mode has been devised. 
 An alternative frequency domain  technique for the Nexrad radar separately models the clutter and weather signal as  gaussian-shaped spectra and separates these two components of the doppler spectrum  using digital search algorithms and then removes these clutter components while leav - ing the underlying weather signal unperturbed.61 Thus, when the gaussian assumptions  apply, the remaining weather signal spectrum provides an unbiased estimator for all  the weather parameter spectrum moment estimates. Typical Weather Radar Designs.  There is no universal weather radar system  design that can serve all purposes. 
 SEC. 113) WAVEGUIDE 403 types ofmetal hose orconduit areproduced. Amolded rubber sheath pressurizes and protects the piece, aswell asholding the adjacent turns intight contact. 
 Applying tlie law of cosines to tlie geometry of Fig. 14.12 gives  Df = D: + D: - 2D,Db cos rl/, (14.32)  OTHER RADAR TOPICS555 Thefencecoverage ofthebistaticradarisseentobequitedifferent fromthehemispherical coverage ofthemonoslatic radar.Similarcoverage canalsobeobtained withthemonostatic radarbyoperating withfixed.ratherthanscanning, antennas. Theradiated signalfromthebistatictransmitter asshowninFig.14.12arrivesatthe receiver viatwoseparate paths.onebeingthedirectpathfromtransmitter toreceiver. 
 1980 ,17, 185–203. [ CrossRef ] 31. Gennert, M.; Negahdaripour, S. 
 The name derives from afamiliar exercise inthePalmer system ofcalligraphy. Other complex scans have been used mainly inexperimental equip- ment, Probably themost useful ofthese isascan inwhich theelevation (orazimuth) angle oscillates rapidly while the azimuth (orelevation) angle oscillates slowly. MECHANICAL SCANNERS Inmost cases theentire radar antenna isput through certain angular motions inorder tomake thebeam scan. 
 RANGE LOCATIONS ARE SORTED ACCORDING TO THEIR PROCESSED TIME DELAYS AND CROSS 
 A. P. Ueam. 
 Touzi, R.; Raney, R.K.; Charbonneau, F. On the use of permanent symmetric scatterers for ship characterization. IEEE T rans. 
 , 
 GETS WERE GEOLOCATED TO AN ABSOLUTE  ACCURACY OF BETTER THAN  M ETERS  AND MOVING  TARGET VEHICLES TO AN ABSOLUTE ACCURACY OF ABOUT  METERS 3TIMSON  ALSO DISCUSSES  THESE !.!0' 
 OFF SWITCH THAT TURNS THE RECEIVER hONv AT THE LEADING EDGE OF THE TARGET ECHO PULSE AND hOFFv AT THE END OF THE TARGET ECHO PULSE TO ELIMINATE UNDESIRED ECHOES 4HE RANGE 
 When a target is dominated by one large echo (such as a metal roof oriented to give  a strong return), the distribution is better described by that for a sine wave in noise.  If the large echo is considerably stronger than the mean of the remaining contributors  to the return, this approaches a normal distribution about the value for the large echo.  This situation is particularly common for near-grazing conditions.17 ch16.indd   13 12/19/07   4:54:58 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 867-875, 1966.  77. Joseph, R. 
 Cantrell, B. H.: A Short-Pulse Area MTI, NRL Report 8162, Naval Resean:h Laboratory, Washington,  D.C., Sept. 22, 1977. 
 Several examples of radar pulse  klystrons will be briefly mentioned. The VA-87E, shown in Fig. 6.10, is a 6-cavity, S-band  klystron tunable over the range from 2.7 to 2.9 GHz. 
 621, 1925.  33. Espenshied. 
 Onthe other hand, occasions arise inwhich anaircraft can usefully employ information collected from another site. Inany ofthese cases, the possibility ofmultiple dissemination ofthe data tomany points offers attractive possibilities. Prior tothe advent ofradar relay such transmission was done by voice ornot atall. 
 Itissupported byaring bearing larger than thetube face and isusually turned bymeans ofahand crank towhich adata transmitter may beattached ifdesired. Readings are made from a circular scale attheedge ofthetube. FixedElectronic AngleIndices.—An electronic angle index can be provided bybrightening thecathode-ray tube forafew sweeps sothat a. 
 N=I, corresponding to the rectang- ular time envelope, is included for comparison. For N = 2, 3, and 4, the list corresponds very closely to stepped-antenna-aperture distribu- tions49optimized by the criterion of maximizing the percentage energy included between the first nulls of the antenna radiation pattern. Amplitude and Phase Distortion. 
 Beam-forming at IF is possible since  phase is preserted duririg frequeticy translation frotri RF to IF (except for the constant phase  qliift introduced by the cotiiri~ori local oscillator).  Blass beam-forming array.'-he RF beam-forming principle shown in ~1~. 8.26 has been  used in tile ~SHR-I. 
 Human activities are driving factors and make subsidence happen. Therefore, land subsidence is caused by a combination of natural conditions and human activities. 6. 
 RANGE CLUTTER WILL NOT CANCEL AND EITHER THE 02) MUST BE INCREASED OR THE 02) MUST BE MADE CONSTANT OVER THE AZIMUTH ANGLES FROM WHICH THE AMBIGUOUS RANGE CLUTTER IS RECEIVED !ND BE FOREWARNED OF A PITFALL INTO WHICH MANY RADAR DESIGNERS HAVE FALLEN &OR EXAMPLE  WHEN PRESENTED WITH THE REQUIREMENT TO TRACK  TARGETS  THE DESIGNER MAY NOT REALIZE THAT RADAR RETURNS FROM THE   TARGETS OF  INTEREST MAY BE EMBEDDED IN SIMILAR RETURNS FROM THOUSANDS OF UNWANTED TARGETS ! TYPICAL LONG 
 Bur. Stand., Sec. D . 
 IEEE (London), vol. 93, pt. IIIA, p. 
 Because the capacitance of the collector-base junction appears as a  deleterious parasitic electrical component, the emitter-periphery to base-area ratio,  or Ep/Ba, is maximized where possible. Generally, higher-frequency devices exhibit  higher Ep/Ba ratios; and to obtain a high Ep/Ba ratio very fine line geometries are  required, where the term geometry  refers to the surface construction details of the  transistor dice. Silicon LDMOS FET . 
 From the color distribution, both rheological parameters gradually varied near Xiti Fourth Road, whereas a clear color change boundary appeared next to Zhongxinhe Road. According to the ﬁeld investigation of the area, from Xiti Fourth Road to Anlite Bridge along the route, breeding ponds (see the little black rectangles in Figure 8) and villages were densely distributed, and few typical urban buildings could be found near this stretch. The soil along this segment was mainly mucky clay and silty clay, as mentioned in Section 4.1. 
 OUTPUT )/   AND A MASTER CONTROL UNIT -#5  4HE 030S PERFORM SIGNAL PROCESSING ON ARRAYS OF SENSOR DATA 4HE '00S PERFORM PROCESSING IN WHICH THERE ARE LARGE NUMBERS OF CONDITIONAL BRANCHES 4HE -#5 ISSUES PROGRAMS TO 030S  '00S  AND "-  AS WELL AS MANAGES OVERALL EXECUTION AND CONTROL 4YPICAL PROCESSING SPEED IS  -)03 MILLIONS OF INSTRUCTIONS PER SECOND  PER CHIP BUT MIGHT BE  ')03 BILLIONS OF INSTRUCTIONS PER SECOND  IN THE NEAR FUTURE  #LOCK FREQUENCIES ARE LIMITED  BY ON 
 TOR  RESULTING IN A LOSS IN RADIATED POWER )N ADDITION  A MISMATCH PRODUCES STANDING  WAVES ON THE FEED LINE TO THE ANTENNA 4HE VOLTAGE AT THE PEAKS OF THESE STANDING WAVES IS    \ ' \  TIMES GREATER THAN THE VOLTAGE OF A MATCHED LINE  WHERE  ' IS THE VOLTAGE  REFLECTION COEFFICIENT 4HIS CORRESPONDS TO AN INCREASED POWER LEVEL THAT IS     \ ' \    TIMES AS GREAT AS THE ACTUAL INCIDENT POWER 4HEREFORE  WHILE THE ANTENNA IS RADIATING LESS POWER  INDIVIDUAL COMPONENTS MUST BE DESIGNED TO HANDLE MORE PEAK POWER 7ITH ANTENNAS THAT DO NOT SCAN  THE MISMATCH MAY OFTEN BE TUNED OUT BY CONVENTIONAL TECH 
 However, in order to keep their generality, dictionary matrixes of the two interferometric channels should be represented separately. In order to reduce the sampling data of each interferometric channel effectively, the M/prime(M/prime≤M) angular position is randomly selected to transmit signal in the azimuth direction, and then N/prime(N/prime≤N) frequency point is randomly selected in the distance direction. After compressed sampling, the interferometric echo signal model can be represented as follows: s/prime=Φs=/bracketleftBigg Φ10 0Φ2/bracketrightBigg s=ΦAg+Φe=A/primeg+e/prime, (14) where, s/primerefers to CS echo signal with the size of 2 N/primeM/prime×1,Φi=Φa i⊗Φr irefers to the measurement matrix corresponding with each channel, ⊗refers to the Kronecker product, A/primerefers to the sensing matrix with the size of 2 N/primeM/prime×PQ,grefers to the scene backscatter coefﬁcient with the size of 2PQ×1, and e/primerefers to noise with the size of 2 PQ×1. 
 MENTS  OF A FEW WATTS PEAK POWER EACH  ADD UP TO MANY HUNDREDS OF PEAK RADIATED POWER 0HASE CONTROL OF THE ELEMENTS IS A CRITICAL PARAMETER  USUALLY REQUIRING ADAPTIVE TEMPERA 
 CENTERED REGION AND AN %ARTH 
 Assuming an array matched at broadside, resistive mismatch off  broadside results in 7 percent·of-the power reflected at the maximum scan angle. The beam­ width at the maximum scan angle is 1.75 times that of the broadside beamwidth. The reduction  in gain is 2.8 dU. 
 13.4 for the detection of targets in sea clutter have  application for land clutter as well. MTI and high resolution are two important examples.  High-resolution results in a probability density function that is non-Rayleigh for both land  and sea clutter, but the spatial distribution of land clutter provides interclutter visibility that  permits the detection of targets that lie outside the separated clutter patches of large <1°. 
 Du, Z.Y.; Ge, L.L.; Ng, A.H.M.; Zhu, Q.G.Z.; Yang, X.H.; Li, L.Y. Correlating the subsidence pattern and land use in bandung, indonesia with both sentinel-1/2 and alos-2 satellite images. Int. 
 While by applying the imaging approach (global sparsity Euclidean norm) proposed in this paper, the height of target scattering point can be estimated more accurate. 165. Sensors 2018 ,18, 3750 Figure 6. 
 RELATED  OR INTENTIONAL EVENTS WARRANTING ATTENTION !N ISSUE ONE ENCOUNTERS WHEN DISCUSSING RADAR PERFORMANCE IS THE CHOICE OF  PERFORMANCE CRITERION &ROM THE USERS PERSPECTIVE  IT MAY SEEM LOGICAL TO MEASURE PERFORMANCE IN TERMS OF TIME TAKEN TO ESTABLISH A TRACK ON A GIVEN TARGET  AVERAGED OVER TIME AND COVERAGE  SINCE TRACKS ARE THE ESSENTIAL PRODUCT DELIVERED TO USERS BY THE RADAR /F COURSE  THIS PLACES THE ONUS ON THE TRACKING SYSTEM  SO ONE MIGHT STEP BACK A LITTLE AND CHOOSE INSTEAD 3.2 ACHIEVABLE ON A GIVEN TARGET  AGAIN AVER 
 PLUS 
 is used in the radar equation, as in Eq. (2.7).  Corisider an IF amplifier with bandwidth BIF followed by a second detector and a video  arnplificr witli baridwidth B,. 
 This is discussed in more detail in Chap. 2; for present purposes it suffices to state that for a signal to be reliably detected it must be larger than noise (generally by 10 to 20 dB) at the point in the receiver where the detection decision is made. The minimum detectable signal can be ex- pressed as the signal-to-noise ratio (SIN) required for reliable detection times the receiver noise. 
 BAND NOISE AND THUS INCREASES SIGNAL 
 Aneven more serious difficulty iscaused bythe“spike” energy, which, because itoccurs asan extremely short pulse, contains avery wide range offrequency com- ponents. Spurious frequencies present inthe spike mask the desired informat ion. Asuccessful corrective hasbeen tosuppress thei-famplifier. 
 There is no clear upper boundary for this part of the curve, but a value near ka = 10 is generally accepted. The region ka > 10 is dominated by the specular return from the front of the sphere and is called the optics region. For spheres of these sizes the geometric optics approximation ira2 is usually an adequate repre- sentation of the magnitude of the RCS. 
 Thisisaresultofthedirectandsurface-reflected signalsreinforcing and. canccli~ig each otlier as tlie rclativc pl~asc bctweeri tlie two patlis varies. A change in frequency  also changes the phase relationship between the two signals. 
 The current sensitivity ofthe coils should bemade ashigh asprac- ticable since this minimizes power losses. For agiven geometry, the sensitivity isdirectly proportional tothe number ofturns, which should therefore beashigh aspracticable. However, foragiven rate ofdeflec- tion (i.e., agiven rate ofchange offlux) thevoltage induced inthecoil is directly proportional tothenumber ofturns. 
 The distance between the center point target and the rest of the point target in the azimuth direction is 135/1.35 ×0.3 = 30 m, and the distance between the center point target and the rest of the point target in the range direction is 120/1.2×0 . 3=3 0m , which is consistent with the scenario layout. Figure 13b is a result of interpolation of the point (1025−135, 2050−120) in Figure 12a. 
 Prediction of Radar Range   ..................................... 2.1  2.1 Introducti on  .............................................................  2.1  Definitions  ......................................................... 
 / 
 In order  to support 25-km along-track resolution, the radar’s sequencer had to cycle through all  antenna patterns within 3.74 s, resulting in a maximum dwell time of 470 ms within  each of the eight footprints. Cross-beam resolution was determined by doppler analysis.  However, since the mean doppler offset was a function of antenna orientation (as well  as incidence), the return from each direction needed its own LO offset. 
 In a spherical-coordinate system, the two coordinates q  and f define points  on the surface of a unit hemisphere. As shown in Figure 13.8, q  is the angle of scan  measured from broadside and f is the plane of scan measured from the x axis. V on  Aulock43 has presented a simplified method for visualizing the patterns and the effect  of scanning. 
 Note that an f/B ratio  of 0.01 corresponds to a doppler shift associated with approximately a Mach 1 target  at a S band carrier frequency. In general for P(n, k) waveforms, the integral of the weighting function provides  the relationship between time and frequency modulation as shown in Eq. 8.23:   t Tk k x dxnf B= + − −∫11 2πππ [ ( )cos( )] (8.23) Since frequency modulation is proportional to the time derivative of phase, phase  is obtained by integrating the frequency with respect to time. 
 Eng. 2015 ,12, 974–977. 50. 
 This beamwidth was sufficient togive warn-. SEC. 614] PRECISION TRACKING OF ASINGLE TARGET 207 ingcoverage ofthe tail cone without the necessity forscanning. 
 Hence the code elements af for i = 1,3, 4, 5, 9 are 1, and the sequence is —1, 1, —1, 1, 1, 1, -1, —1, -1, 1, —1, or 10100011101. The periodic autocorrelation function of this sequence has a peak of 11 and a uniform sidelobe level of — 1. Also, the numbers of Is and Os are approximately equal; the number of Is is one more than the number of Os. 
 Therangeandthecross-range recorded signalsmaybetreatedasorthog­ onalaspectsofasingletwo-dimensional filtering operation. Although themcualSARoptical processing provides dechirping (matched filtering) ofthelinearFMpulse-compression waveform, thechirpmodulation ofthetransmitter isaccomplished asinotherpulse­ compression radars. OtheraspectsofSAR.TheSARhasbeendescribed asaside-looking radarwi,htheantenna beamdirected perpendicular tothepathofthevehiclesuchthatthedoppler frequency of scalterers illuminated bythecenteroftheantenna beamiszero.Itispossible. 
 T. Elfouhaily, B. Chapron, K. 
 55. llrukey, D. L., and L. 
 2.7  determines the signal-to-noise ratio. This is the signal-to-noise ratio that is used in tht: eqlta-  tion for minimum detectable signal [Eq. (2.6)]. 
 The real difficulty with  this definition is, however, the lack of a precise definition of the doppler velocity inter - val, which is to be used for the required “uniform” averaging. Originally, this averag - ing was assumed to involve multiple PRF intervals based on classical low PRF radars  using a single MTI filter. It was for this reason that the MTI Improvement Factor defi - nition (I) provided in the 2nd edition of this Radar Handbook  used the noise gain of  the doppler (MTI) filter as the normalizing factor. 
 PHASE VARIATION ACROSS THE APERTURE WITH A MAXIMUM VALUE AT THE  EDGES OF   $$YP LMAX F F,RAD  WHERE $F  F  IS THE FRACTIONAL CHANGE IN FREQUENCY 4HIS LINEAR 
 TIME FILTERING v IN  3IGNAL 0ROCESSING  )) 4HEORIES AND !PPLICATIONS   ( 7 3CHUSSLER ED   .ORTH (OLLAND %LSEVIER 3CIENCE 0UBLISHERS  " 6  PP n  * ' 3CHOENENBERGER AND * 2 &ORREST  h0RINCIPLES OF INDEPENDENT RECEIVERS FOR USE WITH CO 
 Alsoincluded underthesubjectofpropagation istheexterllal /loiseenvironment inwhichtheradarfinds itself.Theradarisalsoaffected bythere.ffectio/l, orbackscatter, ofenergyfromtheearth's surfaceandfromrain,snow,birds,andotherclutterobjects: butthissubjectis"reserved for Chap.13.Tjleeffectsofpropagation wil1modifythefree-space performance oftheradar.as wellasintroduce errorsintheradarmeasurements. ItislIsuallyconvenient todistinguish between twodifferent regionswhenconsidering radarpropagation. Oneistheoptical,orillte,/erellce, region,whichiswithinthelineofsight (directobservation) oftheradar.Theotheristhedurractioll region,whichliesbeyondtheline ofsight.orbeyondthehorizon, oftheradar.Radarenergyfoundinthisregionisusuallydue todiffraction bythecurvature oftheearthorrefraction bytheearth'satmosphere. 
 ERN SYSTEMS  THE RESOLVER PERFORMANCE IS IMPROVED BY USE OF FERRITE SWITCHING DEVICES TO REPLACE THE MECHANICAL ROTATING COUPLER #ONOPULSE #ONOPULSE ALSO CALLED  SCAN WITH COMPENSATION  IS A RADAR TRACKING  TECHNIQUE THAT IS A COMBINATION OF MONOPULSE AND CONICAL SCAN   ! PAIR OF ANTENNA  &)'52%     "LOCK DIAGRAM OF A TWO 
 D. Baker: Signal Processing Devices Using the Charge-Coupled Concept,  Microelectronics, vol. 7. 
 The noise power decreases approximately as I//2 at larger offsets. The corresponding AM noise is 150 to 160 dB below the carrier. As the local-oscillator signal of a CW radar is usually de- rived from the transmitter, it too will show comparable amounts of noise. 
 Composite-Surface Hypotheses.  Since it is not clear how to extend straightfor - ward GBVP solutions beyond the limiting approximations described above, a heuristic  model was developed that viewed the sea as a carpet of Bragg scattering “wavelets”  modulated by the motions of the larger waves on the surface.102–104 This composite  surface model  is often referred to as the two-scale  model , in which it is imagined that  the surface-wave spectrum can somehow be separated into two parts, one containing  low-amplitude “Bragg scattering wavelets” whose integrated rms waveheight satisfies  the conditions of Eq. 15.16 and another that contains only the longer waves that tilt  and stretch and otherwise modulate the Bragg waves, affecting the Bragg scatterers  through a modulation transfer function ,105 as well as providing a specular component  resembling Eq. 
 FORWARD TERMS ONLY  MEANING THAT THE OUTPUT VALUES ONLY DEPEND ON THE INPUT VALUES WITH NO FEEDBACK TERMS &IGURE  DEPICTS THE GENERAL FORM FOR AN INFINITE IMPULSE RESPONSE ))2  FILTER  ))2 FILTERS MAKE USE OF FEED 
 TO 
 (This and other automatic detectors are described in  hec. 10.7 and in Ref. 70.) By locating the center of the n pulses, an estimate of the target's  angular direction can be obtained. 
 Nominal  instrument mass is 280 kg. PALSAR.  Although based on J-ERS-1 heritage, PALSAR29 is an excellent early  example of multimode space-based SARs. 
 The output frequency ofadirect-connected alternator will beless than 60cpsbythe slip ofthe induction motor. This results inanoutput frequency of 57to58cps, which isnormally satisfactory forthe operation oftrans- formers orother 60-cycle equipment. There isnoreally satisfactory means now available forregulating the output voltage ofthe alternator. 
 The servo loop that  points the antenna is made relatively wideband (high data rate) to permit a fast tracking  response against targets with high angular acceleration. The process of adjusting the predicted  position based on the measured position is performed with a narrow bandwidth. This error-  signal bandwidth is adaptive and can be made very narrow to obtain good signal-to-noise  ratio, yet the system will continue to point open-loop based on the stored target-trajectory  prediction and the wide tracking-bandwidth of the antenna-pointing servos. 
  D" RESPONSE TO CLUTTER AT  4HE FILTER SIDELOBES BETWEEN  AND   DOPPLER PROVIDE THE SPECIFIED CHAFF REJECTION OF  D" ! MIRROR IMAGE OF THIS FILTER IS USED FOR THE THIRD MOVING DOPPLER FILTER 4HE MIRROR 
 April. 1956.  90. 
 Not only is this a function that makes the integral  analytically tractable, but it also gives exactly the same results as geometric optics.62  Since it fails, like geometric optics, to explain frequency variation, it cannot be a truly  representative correlation function, although it gives a scattering curve that fits several  experimental curves near the vertical. The next most frequently used function is the  exponential:  ρ ξξ( )| |/=−eL (16.6) This has some basis in contour-map analysis;60 the results fit both Earth and lunar  radar return over a wider range of angles than the gaussian 60,63 (but sometimes not  as well near vertical). Furthermore, it has the merit that it exhibits frequency depen - dence. 
 an increasing absolute value of the monopulse ratio/(6). It can be shown that the boresight sensitivity of full-vector monopulse with a uniform sum beam can be maximized at a value of approximately 1.8 by employing a linear-odd aperture illumination function to generate the delta beam. The second curve in Fig. 
 SYNTHETIC APERTURE RADAR  17 .276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 The corresponding velocity separation is ∆v = ± fvib l /2, and the crossrange  displacement is then  ∆∆ Ω∆rv v VRf R= = = ±vib avg 2Vλ  (17.48) where l avg = average wavelength (assuming low fractional bandwidth). The relative  amplitude of each of the paired echoes is  V oltage:  φ π λo d 22= avg (17.49)  Power:  φ π λo d 222 2  =  avg (17.50) Thus, the amplitude of the paired echoes is proportional to the square of the vibra - tion amplitude, and crossrange displacement is proportional to the vibration frequency  (see Section 7.5.2 of Sullivan1). For bright, point-like targets, or for targets such that 4 p  d is not small compared  to l, additional terms should be retained in Eq. 
 Note that the beam position is not  symmetrical with frequency. To scan the beam ±45° about broadside requires a bandwidth of  almost 30 percent with a wrap-up factor of 5, and 7 percent for a wrap-up factor of 20.  (Percentage bandwidth = 100 ~flfo .)  A frequency-scan radar requires a considerable portion of the available band or a radar t_o -·······-~ be devoted to beam steering. 
 To accomplish this the signal processor must provide at least 60 dB improvkment factor,  which is a difficult task.56 Not only must the signal processor be designed to reduce the clutter  by this amount, but the receiver must be linear over this range, there must be at least eleven  ">, bits in the AID converter of the digital processor, the equipment must be sufficiently stablc,  and the number of pulses processed (for reducing antenna scanning modulation) must be  sufficient to achieve this large value of improvement factor.  4.9 NONCOHERENT MTI  The composite echo signal from a moving target and clutter fluctuates in both phase and  amplitude. The coherent MTI and the pulse-doppler radar make use of the phase fluctuations  in the echo signal to recognize the doppler component produced by a moving target. 
 GENERATED  GRAVITY WAVES v * 0HYS /CEANOGR  VOL   PP n    " +INSMAN  7IND 7AVES  %NGLEWOOD #LIFFS  .* 0RENTICE 
 In this chaptel-, the receiver design is considered  mainly as a problem of extracting desired signals from noise. Chapter 13 considers the problem  of radar design when the desired signals must compete with clutter. The current chapter also  includes brief discussions of radar displays and duplexes. 
 A high-mu grid is also feasible for all but the very highest power linear-beam tubes, and it greatly simplifies the mod- ulator requirements; but it raises the cost and may lower reliability and life of the tube. Magnetic Field. Except for a few electrostatically focused klystrons,34'35 all magnetrons, CFAs, klystrons, and TWTs require a magnetic field to control the path of the electron beam. 
 729–740, July 1992. 66. K. 
 Whitham, and W. G. Elford, “Response of high frequency radar to meteor  backscatter,” J. 
 TIZATION NOISE AND INTERNAL 
 Ê  9-- 2EFLECTOR ANTENNA ANALYSIS METHODS CAN GENERALLY BE LUMPED INTO THREE CLASSES OR CATEGO 
 M. Hofstetter, “Digital pulse compression via fast convolution,”  IEEE Trans. on Acoustics,  Speech and Signal Processing , vol. 
 The common assumption about the na- ture of thermal noise, well justified by practical experience, is that it is a narrowband zero-mean gaussian random process. A particular pair of samples consisting of in-phase (/) and quadrature (Q) components can be properly . TABLE 20.4 Relationship of Target Height Error to Radar Range and Elevation Angle Measurement Errors* Flat earth: a/, = (<rR2 sin2 0 + /?2cre2 cos2 6)1/2 Spherical earth: parabolic approximation: <*h = \.vR2(RIRe + sin 0)2 + /?2ae2 cos2 O]172 Spherical earth: exact geometry: a* = {[<r*2(*2 + (Rf + ha)2 sin2 0) + (R e + ha)2R2aB2 cos2 W(Rf + /02}"2 Re = effective earth radius = kR0 ha = antenna height above earth surface R = radar-measured target range 0 = radar-measured target elevation angle h = radar-measured target height &R = rmse of radar range measurement (J0 = rmse of radar elevation-angle measurement vh = rmse of target height estimate *Colocated and exactly known platform-antenna location and orientation and small mea- surement errors relative to target coordinate values are assumed. 
 18.21 (a) Closed-loop frequency-response characteristics of two servosystems. (b) Their corresponding time response to a step input.SYSTEM A SYSTEM B FREQUENCY (Hz) (a) SYSTEM A SYSTEM BVOLTS ANGLE . To maximize the servo closed-loop bandwidth for a given motor drive system, tachometer feedback must be used. 
 The range of interest is O ::; 2a 1 ::; a0 which covers the span  from uniform illuminations to a taper so severe that the illumination drops to zero at the ends  of the array. (The array is assumed to extend a distance d/2 beyond each end element.)  The above applies to a linear array. Similar results apply to a planar aperture; 17•18 that is,  the beamwidth in the plane of the scan varies approximately inversely as cos 00, provided  certain assumptions are fulfilled. 
 H.: " Man and Radar Displays," The Macmillan Company, New York, 1962.  52. Swerling, P.: The " Double Threshold" Method of Detection, Rand Corp. 
 Comments on Hardware.  On a popular American children’s television pro - gram, one is told that “It is not easy being green.” Likewise, it is not easy being  TABLE 18.1  Spacecraft Velocities Body Mass (kg) Radius (km) Altitude h (km) VSC (m/s) hVSC (km2/s) Earth  5.97 × 10246380 800 7466 6000 Venus  4.87 × 10246052 300 7151 2200 Mars 6.4 × 10233397 400 3353 1600 Ganymede 1.4 × 10232631 100 1849  185 Calisto  1.08 × 10232400 100 1697  170 Moon  7.35 × 10221737 100 1634  160 Europa 4.8 × 10221569 100 1385  140 ‡  N is the standard symbol for Newton, force, with the units m kg s–2. §  The plane of polarization of an EM wave is perturbed by interaction with the magnetic field through which it passes,  an effect discovered by Faraday. 
 The Joint Surveillance Target Attack Radar System  (Joint STARS) provides long-range airborne surveillance and tracking of sta - tionary and moving ground targets (see Figure 13.47). The phased array antenna  for this system is a 24-ft wide by 2-ft high planar X-band slotted array. It is  mounted inside a radome underneath the fuselage of an E-8A aircraft and can be  mechanically rotated ±100° in elevation for operation looking out either side of  the aircraft. 
 The first sidelobe is 17.5 dB below the main lobe, and  tlie beamwidth is 58.5L/1).  The effect of tapering the amplitude distribution of a circular aperture is similar to  tapering the distribrltio~l of a linear aperture. Tile sidelobes may be reduced, but at the expense  of broader beamwidtli and less aritenrla gain. 
 Artificial  dielectric^.^^ 47 Instead of using ordinary dielectric materials for lens antennas, it is  possible to construct them of artificial dielectrics. The ordinary dielectric consists of molecular  particles of microscopic size, but the artificial dielectric consists of discrete metallic or dielec-  tric particles of macroscopic size. The particles may be spheres, disks, strips, or rods imbedded  in a material of low dielectric constant such as polystyrene foam. 
 HORN FEED IS NOT PRACTICAL FOR FOCAL 
 25 28. 1977. IEE (London) Conf. 
 The sea-surface  slope measurement problem is challenging because the desired slope signals are as  small as one microradian, equivalent to a 6 mm height differential (rise) for each 6 km  along-track separation (run). In addition to height precision, geodetic altimetry requires smaller along-track  resolution than a conventional altimeter and an orbit that accumulates dense cross- track coverage. The altimeter’s footprint resolution should be smaller than about 6 km,   *  Literally, measurement of the distance between the mean ocean surface and the local sea floor.FIGURE 18.12  When averaged and stripped of  dynamic (current-driven) features, the mean ocean  surface is a direct expression of the local gravity gra - dient. 
 ' ,•1·i: •  Figurl' 1.1 i\N/MP()-46 <:W trnckcr-i1111minator for the Hawk missile system showing separate transmit­ ting and receiving antennas. (Courtesy Ra_l'tlremt Co.). 74 INTRODUCTION TO RADAR SYSTEMS  usual doppler spectrum of interest.31.69 The normaJ antenna isolation plus feedthrough nul­ ling usually reduces the AM components below receiver noise in moderate power radars. 
 J. Geodyn. 2018 ,114, 41–52. 
 .. ;~-...’, ,>~. I ~ ( k FIG.12.16.—General-purpose receiver. 
 On the right panel the pulse shape at eight frequencies within the pulse is depicted. The selected eight pulses are over-plotted in the top ﬁgure, where the dotted lines separate the on-pulse and o ﬀ-pulse regions used for the left panel. All powers are given in terms of o ﬀ-pulse noise (RMS) [ 12]. 
 44. F. Johnson, Synthetic Aperture Radar (SAR) Heritage: An Air Force Perspective , Ohio: Air Force  Avionics Laboratory, Wright Patterson AFB, June 2003. 
 Younis, R. Lenz, and W. Wiesbeck, “Array Design for Automotive Digital Beamforming Radar System”. 
 MITTER AT THESE LONG BASELINES OR OPERATE WITH SHORTER BASELINES TO ACHIEVE ACCEPTABLE LOW ALTITUDE SURVEILLANCE COVERAGE .OTE THAT THE TWO 
 Introduction Nowadays, thanks to its distinguishing features [ 1,2] GB-InSAR technology has become a consolidated technique for measure ground displacements in many geophysical applications [ 2–4] and has proved to be particularly suitable in environments where continuous and real-time monitoring is required [ 5,6]. Despite the high number of technological advances seen in the last decade, some typical limitations are still present in the standard GB-InSAR systems, and therefore many improvements can be performed with respect to the current technique. Some of the persisting GB-InSAR limitations are related to its mechanical scanning. 
 7  indicates that a signal-to-noise ratio of 13.1 dB is required to yield a 0.50 probability of  detection, 14.7 dB for 0.90, and 16.5 dB for 0.999.  There are several interesting facts illustrated by Fig. 2.7. 
  AND DIFFERENCE 
 The  probability density for noise alone [Eq. (2.21)] is plotted along with that for signal and noise  [Eq. (2.27)J with /I/(/:!* = 3. 
 Examples of passive ECM  are chafj decoys, and radar cross-section redirction.  One of the earliest forms of countermeasures used against radar was cl~c!l/: Chaff consists  of a large number of dipole reflectors, usually in the form of metallic foil strips packagect as a  bundle. Tlle many foil strips constituting tlte chaff bundle, on being released Srgnl all iiircraft,  are scattered by the wind and blossom to form a highly reflecting cloud. 
 In the preceding discussion, the signal was represented as a function of time. For present purposes it is preferable to consider the signals as a discrete se- quence numbered from 1 to N. Let Sn represent the signal received when the physical antenna is at the nth position of the antenna array. 
 Mass., 1972, pp. 197-2 1 1.  84. 
 The bandwidth of a coupled-cavity TWT can be 10 to 15%. The ring-bar  has broader bandwidth and higher efficiency than the coupled-cavity circuit, but   it is not capable of as high a power as the coupled cavity. Thus, the bandwidth of a  TWT decreases as its power increases. 
 ARRAYS ARE  IN GENERAL  CHOSEN TO BE IRREGULAR IN THEIR SHAPE AND POSITION TO  AVOID GRATING LOBES )F A JAMMER IMPINGES ON A GRATING LOBE  THE JAMMER WILL BE NULLED BY DISTORTING THE GRATING LOBE AND  AS A CONSEQUENCE  THE ARRAY MAIN BEAM GRATING NOTCH  &OR EXAMPLE  CONSIDER A 5,! WITH  .    ELEMENTS THEN  FORM TWO  TYPES OF NOT OVERLAPPING SUB 
 FREQUENCY(GHz) FIG. 12.25 General land-scattering-clutter model (vertical polarization). Horizontal polarization is very similar. 
 At off-boresight angles, the phase detection error probability depends on the signal-to-noise ratio. At angles far from the beam boresight, the signal-to-noise ratio diminishes, causing the error probability again to approach 0.5. A minimum-error probability-maximum-accuracy condition is reached for intermediate angles. 
 The accuracy of the angle measurement is inversely proportional to the square root of the  signal-to-noise power ratio.' Since the signal-to-noise ratio is proportional to 1/R4 (from the  radar equation), the angular error due to receiver noise is proportional to the square of  the target distance.  Servo noise is the hunting action of the tracking servomechanism which results from  backlash and compliance in the gears, shafts, and structures of the mount. The magnitude of  servo noise is essentially independent of the target echo and will therefore be independent of  range. 
 W. Crispin, Jr. and K. 
 STATE RADARS USING PULSE COMPRESSION WITH PULSE  WIDTHS IN THE  TO  §S RANGE !S AN EXAMPLE  THE THERMAL TIME CONSTANT OF A SILICON DIE WITH A THICKNESS OF  MILS IS APPROXIMATELY  §S WHEREAS A GALLIUM ARSENIDE DIE WITH A THICKNESS OF  MILS IS APPROXIMATELY  §S 4HUS  FOR AN OPERATING PULSE WIDTH &)'52%   /NE LIMIT OF TRANSISTOR CAPABILITY IS DETERMINED BY THE MAXIMUM JUNCTION TEMPERATURE   WHICH IN TURN IS DETERMINED BY THE THERMAL TIME CONSTANT  AND THIS RESULTS IN VERY DIFFERENT CAPABILITIES AS A  FUNCTION OF OPERATING PULSE WIDTH AND DUTY CYCLE               
 Before we discuss the effect ofthe earth’s curvature, we should comment oncertain other, less important, shortcomings ofthepreceding simplified argument. For one thing, wehave ignored the fact that the reflecting suface isnot smooth; even inthecase ofthesea, theirregulari- ties (waves) areboth wide and deep compared toamicrowavelength; in the case ofaland surface, wemay beconfronted with any imaginable irregularity. Nevertheless, atleast forreflection onthe sea atnearly grazing incidence, the observed reflection coefficient israther close to what aglassily smooth sea would give. 
 SCAN TIME SAMPLE TO THE APEX OF A CURVE OF MAXIMUM CONVEXITY 4HE HYPERBOLIC CURVE NEEDS TO BE WELL 
 but the data-processing capability becomes the lim.iting factor. The handling of a large  number of short-range targets in track can drive the processor to full utilization and require  that search operations. which have lower priority than track, be reduced. 
 Poor slow-moving target rejection. Cannot measure radial target velocity. Range ghosts. 
 The synthetic aperture radar, which is discussed in Sec. 14.1, is a  radar in a moving vehicle that provides a high resolution image in both range and in a  direction parallel to the vehicle motion. The latter dimension is sometimes called cross range  when the radar uses a side-looking antenna directed perpendicular to the direction of motion. 
 Harger, R. 0.: "Synthetic Aperture Radar Systems: Theory and Design," Academic Press. New  York. 
 Detection is based on establishing a threshold level at the output of the receiver. If the  receiver output exceeds the threshold, a signal is assumed to be present. This is called threshold  detection. 
 TO 
 4.3.2 Strobe unit type 63 The signals from the radar receiver were ampli ﬁed and strobed in order to obtain bearing (D/F), velocity and range information on a target. The DC misalignment voltage fed to the ampli ﬁer was also fed to the AGC valve, the anode current of which controlled the screen voltages in the IF and head ampli ﬁers during ‘Auto ’ operation. These functions were undertaken in strobe unit type 63, illustrated inﬁgure 4.11. 
 Figure 4.6 illustrates the general case where the  gate spacing ts, the gate width tg, and the transmitted pulse tt are all unequal. Selecting  tt = tg maximizes target return signal-to-noise ratio and, as a result, range performance.  Selecting tg > ts creates overlapped range gates and reduces the range gate straddle  loss (Section 4.6) but can increase the possibility of range ghosts unless contiguous  detections from straddled target returns are “clumped” prior to the ambiguity resolu - tion (Section 4.4). 
 Colernan: Applications of the Luneburg Lens, Naval Research Lab. Rrpt.  48R8. 
 According to  Guerlac,' the first tests of the 60-MHz pulse radar were carried out in late December, 1934,  and early January, 1935. These tests were "hopelessly unsuccessful and a grievous disappoint-  ment." No pulse echoes were observed on the cathode-ray tube. The chief reason for this  failure was attributed to the receiver's being designed for CW communications rather than for  pulse reception. 
 This is accomplished hy utilizing a  radar with circular polarization or with crossed linear polarization.  A circularly polarized wave incident on a spherical scatterer is reflected as a circularly  polarized wave with the opposite sense of rotation and is rejected by the antenna that orig­ inally transmitted it. With a complex target such as an aircraft the reflected energy is more or  less equally divided between the two senses or rotation so that some target-echo energy is  accepted by the same radar antenna that transmitted the circularly polarized signal. 
 ,  Ê-"1, 
 For  a given coherent processing time, more energy is placed on the target, which improves  detectability. For this reason, high PRF is used for long-range search of high-speed  closing targets.FIGURE 4.5  Clutter-plus-noise-to-noise ratio in range-doppler space Main-beam ClutterSidelobe Clutter“Clutter-free” Region Range Gate Number Filter Number (256-Point FFT)20 0 5 0 100 150 200 2502030 10405060 406080100120140160 0 100 200 300 400 5001020304050Range Gate Number (Clutter + Noise)/Noise (dB) Main-beam Clutter Altitude-line Sidelobe Clutter“Clutter-free” Region Filter Number (512-Point FFT)Medium PRF (PRF = 24 kHz, Alt = 1400 ft) High-medium PRF (PRF = 69 kHz, Alt = 1300 ft)Main-beam Altitude-line Altitude-line ch04.indd   8 12/20/07   4:52:00 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
   !  
 tliat is enhanced with a slow AGC. Under practical tracking conditions it seems that a  wide-bandwid th (short-time constant) AGC should be used to minimize the overall tracking  noise. However, tlie servo bandwidth stiould be kept to a minimum consistent with tactical  reqr~irenients in order to minimize the noise. 
 l'liys. Soc.  scr. 
 Thisiscalled(l/lxdril'(,.Ithasthefurtheradvantage ofhavingrcduced temperature sensitivity. Insfeadofusinganumberofindividual toroidsofdifferent lengthsin cascade. asinglelongsectionoftoroidisusedthatiscapableofproviding thetotaldifferential phaseshiftof360°.Therequired digitalphaseincrement isobtained byoperating onaminor hysteresis loop.asinFig.R.12.IfBr(I).forexample, weretheremancnt magnetization needed toproduce aphasechangcof1800relativetotheremanent magnetization -Br,theamplitude and\....idthofthedrivingpulsewouldbeselected soastoriseuptopointIonthehysteresis curve.Whenthecurrentpulsedecaysto zero,themagnetization fallsbacktotheremanent valueBr(I)alongtheindicated curve.Thedifference inphasebetween -Br(I)andthevalue nr(I)determines thephaseincrcment. 
 ATED HORIZONTAL BEAMWIDTHS RANGING FROM ABOUT  TO LESS THAN  0ULSE LENGTHS ARE SWITCHABLE  GENERALLY IN THE RANGE FROM  NS TO  §S  WITH 02&S RANGING FROM  TO   (Z OR MORE 0LEASURE CRAFT SYSTEMS TYPICALLY HAVE PEAK POWERS OF  n  K7 AND UTILIZE ANTENNAS WITH HORIZONTAL APERTURES AS SMALL AS  MM AND GAINS OF ABOUT  D" 4HESE ALL OPERATE AT  '(Z 4HE GREATEST TECHNICAL CHALLENGE IN DESIGNING MARINE RADARS IS TO MAINTAIN GOOD TARGET DETECTION IN HIGH LEVELS OF SEA AND PRECIPITATION CLUTTER 0RECIPITATION #LUTTER  )T IS WELL KNOWN THAT CIRCULAR POLARIZATION #0  CAN BE A  COUNTER TO RAIN CLUTTER BECAUSE ITS REFLECTION IS PREDOMINATELY CROSS 
 MITTER 3IMILARLY  COMBINING THE POWER OUTPUTS OF MULTIPLE MAGNETRONS HAS NOT BEEN ATTRACTIVE -AGNETRONS CAN PRODUCE CONSIDERABLE ELECTROMAGNETIC INTERFERENCE ACROSS A BANDWIDTH MUCH WIDER THAN THE SIGNAL BANDWIDTH COAXIAL MAGNETRONS ARE SOMEWHAT BETTER IN THIS RESPECT  !LSO  MAGNETRONS DO NOT HAVE PRECISE FREQUENCY CONTROL NOR ARE THEY ABLE TO PERFORM PRECISE FREQUENCY JUMPING )N SPITE OF ITS MANY UNFAVORABLE CHARACTERISTICS  THE MAGNETRON IS A TUBE THAT CAN BE  CONSIDERED FOR LESS DEMANDING RADAR TASKS &OR A LONG TIME  IT WAS THE TRANSMITTER OF CHOICE FOR USE IN THE CIVIL MARINE RADAR  ONE OF THE MOST WIDELY USED RADARS  AS BRIEFLY  DISCUSSED NEXT #IVIL -ARINE 2ADAR -AGNETRONS  4HE MAGNETRON HAS BEEN WELL 
 Transmitter  Circulator Antenna  TR tube Diode  ,__----..,(radioaclive -,____,,__, limiter  primed)  Passive TR-limiter RECEIVERS, DISPLAYS, AND DUPLEXERS 365  Receiver  Figure 9.9 Circulator and receiver protector. A four-port circulator is shown with the fourth port ter­ minated in a matched load to provide greater isolation between the transmitter and the receiver than  provided by a three-port circulator.  Circulator and receiver protector. 
 26. Thor, R. C.: A Large Time-bandwidth Product Pulse-Compression Technique, IEEE Trans., vol. 
 E. Nahi: The Detection of Moderately Fluctuating Rayleigh  Targets, IEEE Trans;, vol. AES-12, pp. 
 Consequently, the most basic requirement on the definition of Pt is that it agree with the definition of Pr. For a CW radar, the power (averaged over an RF cycle) is constant, and there is no definition problem. For a pulse radar, both Pt and Pr are usually defined as the pulse power, which is the average power during the pulse. 
 withthein-phase andquadrature components astheaxes,thelocusofthecomplex anglewith targetelevation astheparameter isaspiralpath.Bymeasuring thecomplex angle,thetarget elevation canbeinferred.52Inusingthecomplex-angle technique, theradarantenna isfixedat someangleabovethehorizonandtheopen-loop measurement ofcomplex angleiscompared withapredicted setofvaluesfortheparticular radarinstallation, antenna elevation-pointing angle,andterrainproperties. Agivenin-phase andquadrature measurement doesnotgivea uniquevalueofelevation anglesincetheplotofthecomplex angleshowsmultiple, overlap­ pingturnsofaspiralwithincreasing targetaltitude. Theambiguities canberes_olved with frequency diversity orbycontinuous tracking overanintervallongenoughwrecognize the ambiguous spirals.Inonesimulation ofthetechnique itwasfoundthattracking overa smooth surfacecanbeimproved byatleastafactoroftwo,butoverroughsurfaces the improvement wasmarginal.61 Thusthereexistanumberofpossible techniques forreducing theangleerrorsfoundwhen tracking atargetatlowangle.Someoftheserequireconsiderable modification totheconven­ tionaltracking radarbutothersrequireonlymodification intheprocessing oftheangle-error signals.Ithasbeensaidthatthesevarioustechniques canavoidthelargeerrorsencountered byconventional trackers whentheelevation angleisbetween 0.25and1.0beamwidth. 
 The color bar indicates that darker colors denote a lower aspect entropy which means the pixels are more anisotropic, while the lighter color denotes a higher entropy and more isotropic. The result is as we expected. Pixels from vehicles and calibration targets show up as a dark color because they scatter the wave near a certain angle, which leads to a lower aspect entropy. 
 When analog lines are used,  loop gains are not much larger than 0.9 in the configuration of Fig. 10.lOa, and 0.98 in the  configuration of Fig. 10. 
 AES-4,  pp. 640-644, July, 1968.  55. 
 FIELD WHEREAS SOME GEOPHYSICAL '02 SYSTEMS OPERATE AT LONGER RANGES  M TO  KM   AND THEY . Ó£°£{  2!$!2 (!.$"//+  COULD BE CONSIDERED TO OPERATE IN THE &RESNEL AND EVEN &RAUNHOFER FAR 
 The grid-controlled tube is characterized as being capable of high power, broadband, low  or moderate gain, good efficiency, and inherent long life. Unlike other microwave tubes, the  grid-controlled tube can operate, if desired, with a linear rather than a saturated gain charac­ teristic. In atldition to being used in high-power amplifier chains, the grid-controlled tube has  also seen service in large phased-array radars that operate in the lower radar-frequency bands. 
 ELEMENT PHASE SHIFT IN THE Y DIRECTION 4HE ARRAY FACTOR OF A TWO 
 111 tlie literatirrc ori SAR, tlie radar equation is usually written wit11 tlic  sigtial-to-noise ratio (SIN) 011 tlic left-liand side. We start with tlie followirig  P A~OII SJN = Lz--  4d2kT0 BF, R4  OTHER RADAR TOPICS521 Thisleadstothecondition RuC-<­ ()CI-21'(14.10) Thustheunamhiguous rangeandtheresolution cannotbeselected independently ofone another. Thecondition givenbyEq.(14.10)isoptimistic inthatthereareatleasttwofactorswhich resultintheright-hand portion heingred·uced. 
 SECTION VEHICLE DEIGN 4HE  32 
  ZERO DOPPLER  CLUTTER 
 Pulse-modulated Doppler System.—The last system tobe described works against the heaviest ground clutter, and, inprinciple, onaplurality oftargets and with norestriction onthe relative values ofdoppler and recurrence frequencies. Practically, there are limits onthe last two factors, the limits being setbyquestions ofapparatus complexity. Ablock diagram isshown inFig. 
 Furthermore, it is unnecessarily constraining in many phased array applications, especially where the feeds account for a small fraction of the cost of the total radar. Typically a sum beam may be designed for good detectability and sidelobes. The delta beam is then optimized for accuracy performance, perhaps with other constraints. 
 The loss decreases with increasing number of pulses integrated. With 10  pulses integrated, the loss with 10 independent samples decreases to 0.7 dB, and to 0.3 dB for  100 pulses integrated.88  If the target echo is large, energy can spill over into the adjacent range-resolution cells and  affect the measurement of the average background. Fur this reason, the range cells surround-  ing the test cell are often omitted when averaging the background. 
 The DPCA performance described in the preceding subsection can be ana- lyzed on the basis of radiation patterns or the equivalent aperture distribution function.8 If the radiation pattern is used, the composite performance may be ob- tained either by applying the pattern functions over the entire 360° pattern or by combining the improvement factors for the DPCA main-beam and the sidelobe regions in the same manner as parallel impedances are combined: ^-hr~ <""12)'total *sl 7DPCA If the aperture distribution is used, the sidelobe effects are inherent in the analysis. Care must be taken since if the array or reflector function is used with-TRANSMlTTER HYBRID AMPLIFIERDELAYLINE DELAY LINEARRAY . out considering the weighting of the elemental pattern or the feed distribution, the inherent sidelobe pattern can obscure the main-beam compensation results. 
   -AGELLAN  AND  6ENUS  %XPRESS   &IGURE  IS A SIMPLIFIED SCHEMATIC OF AN %ARTH 
 <;lover, K. M., K. R. 
 FREQUENCY ANTENNA WITH THE LIMITED APERTURE AVAILABLE IN THE MISSILE   (OWEVER  LOW 
 After this single-pulse combina - tion, the actual double cancellation can be performed by any conventional MTI  processing techniques. Power in the Antenna Sidelobes.  Airborne systems are limited in their ability  to reject clutter due to the power returned by the antenna sidelobes. 
 It will be recalled from Sec. 5.6 that a tracking radar can track a  target in range by generating a pair of range gates within the radar receiver and adjusting these  gates to center on the target. The tracking radar is said to be" locked on" the target when the  echo is maintained between the two range·gates. 
 The signals are  frequency modulated so as to avoid the problems associated with the amplitude stability of  acoustic delay-iine cancelers.41 ,.,.,·" . MTI AND PULSE DOPPLER RADAR 127  4.7 EXAMPLE OF AN MTI RADAR PROCESSOR  The Moving Target Detector (MTD) is an MTI radar processor originally developed by the  MIT Lincoln Laboratory for the FAA 's Airport Surveillance Radars (ASR).42-44 The ASR is a  medium range (60 nmi) radar located at most major United States airports. It operates at S  band (2.7--2.9 GHz) with a pulse width of less than 1 µs, a 1.4° azimuth beamwidth, an antenna  rotation rate of from 12.5 to 15 rpm depending on the model, a prf from 700 to 1200 Hz  (1030 Hz typical), and an average power of from 400 to 600 W. 
 The rapid data  acquisition speed of this system has the potential to give new insights into thunder - storm evolution, hurricanes at landfall, hail formation plus microburst, gust front and  tornado genesis mechanisms that may likely evolve into an operational capability . In the early 1990s, the FAA led an effort to develop dual-use weather and aircraft  surveillance radar based on electronic scanning and pulse compression techniques,165  ch19.indd   36 12/20/07   5:39:17 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 VIA, intended to replace ASV Mk. VI, included the additional facility of being capable of locking-on to a target, providing accurate range and bearing measurements that would be automatically updated. This information was providedto the pilot and to the Leigh Light operator. 
 In a  dipole array, the phase is reversed by reversing every other dipole.  Open-ended waveguides are another popular form of array radiator. They are a natural  cxtetision of the waveguide sections in which the phase shifters are placed. 
 conceived and designed the experiments; L.Y. and Y.Z. performed the experiments; L.Y. 
 Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 14.38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 by an incident wave. The absorber is made of flexible, carbon-impregnated plastic  foam cut in the form of pyramids. 
 In the communications mode it searches for, acquires, and tracks the Tracking and Data Relay Satellite System (TDRSS) relay satellites to provide two- way communication between the space shuttle and ground tracking stations. The IRACS hardware is subdivided into deployed and inboard assemblies. The deployed hardware is located within the Shuttle payload bay and is extended for operation through the open payload bay doors. 
 PULSE PHASE DIFFERENCE OF  RAD IN LOCKING THE COHO RESULTS IN  ) LIMITATION OF  D" !S NOTED ELSEWHERE   FREQUENCY CHANGE DURING A PULSE FROM A PULSED OSCILLATOR DOES NOT LIMIT  ) IF IT REPEATS  PRECISELY PULSE TO PULSE  4HE LIMITATIONS ON THE IMPROVEMENT FACTOR THAT ARE DUE TO EQUIPMENT INSTABILITIES IN  THE FORM OF FREQUENCY CHANGES OF THE STALO AND COHO BETWEEN CONSECUTIVE TRANSMITTED PULSES ARE A FUNCTION OF THE RANGE OF THE CLUTTER 4HESE CHANGES ARE CHARACTERIZED IN TWO WAYS !LL OSCILLATORS HAVE A NOISE SPECTRUM )N ADDITION  C AVITY OSCILLATORS  USED  BECAUSE THEY ARE READILY TUNABLE  ARE MICROPHONIC  AND THUS THEIR FREQUENCY MAY VARY AT AN AUDIO RATE 4HE LIMITATION ON THE IMPROVEMENT FACTOR DUE TO FREQUENCY CHANGES IS THE DIFFERENCE IN THE NUMBER OF RADIANS THAT THE OSCILLATOR RUNS THROUGH BETWEEN THE TIME OF TRANSMISSION AND THE TIME OF RECEPTION OF CONSECUTIVE PULSES 4HUS  THE IMPROVEMENT FACTOR WILL BE LIMITED TO  D" IF   O$F 4    RAD  WHERE  $ F IS THE  OSCILLATOR FREQUENCY CHANGE BETWEEN TRANSMITTED PULSES AND  4 IS THE TRANSIT TIME OF   THE PULSE TO AND FROM THE TARGET &)'52%  0HASE INSTABILITY .   -4) 2!$!2  Ó°ÈÇ 4O EVALUATE THE EFFECTS OF OSCILLATOR PHASE NOISE ON -4) PERFORMANCE  THERE ARE FOUR  STEPS &IRST  DETERMINE THE SINGLE 
   !)2"/2.% -4)  Î°Ó£ Î°nÊ * /",  "/" Ê " * 
 Lundien, “Terrain analysis by electromagnetic means: radar responses to laboratory prepared  soil samples,” U.S. Army Waterways Exp. Sta., TR  3-639 , Vicksburg, MS, 1966. 
 SCALE MODEL  WHILE ADDING THE  TWO 
 The high power 1.5 m equipment was installed in a LRASV Mk. II Wellington, with an experimental 100 kW transmitter, using NT. 99 valves and rotary spark gap modulation. 
 STATE !.303 
 0/ COEFFICIENTS 4HUS  -ITZNERS EXPRES 
 Since large power  is not easy to achieve at millimeter wavelengths, it is not likely that radars in this portion of the  spectrum wi11 find wide application for long-range surveillance.  The characteristic wavelengths of the millimeter region are responsive to individual scat­ terers of size comparable to the wavelength. Hence. 
 Figure 15. Two defocused ships are detected in airborne SAR images. Sub-images of ship05 and ship06 are located in airborne SAR image. 
 76- 77  digital, for MTI. 121- 125  Fixed error, FM-CW altimeter. 86-87  Flicker noise, 74, 347-348  Fluid-cooled helix TWT, 207  Flux drive ferrite phase shifter, 295  FM-CW radar. 
 ANTENNA SIDELOBES 4HE RETURNS FROM BOTH CHANNELS ARE COMPARED FOR EACH RANGE 
 Thepoweroutput,anodevoltage,andefficiency areplottedasafunction ofthemagnetron input powerforafixedfrequency andwiththemagnetron waveguide-load matched. Thepeak voltageisseentovaryonlyslightlywithachangeininputpower,butthepoweroutputvaries almostlinearly. Figure6.6hplotsthepoweroutputandvoltageasthetuoeistunedthrough its frequency range,whenthecurrentisheldconstant andthewaveguide loadismatched. 
 TION MODEL IS COMBINED WITH RADAR SYSTEM PARAMETERS  TARGET SCATTERING CHARACTERISTICS  AND (& NOISE DISTRIBUTIONS  THE RADAR EQUATION %Q   CAN BE SOLVED TO PREDICT THE RADARS PERFORMANCE  AS TREATED IN 3ECTION  4HIS IS THE BASIC APPROACH EMPLOYED WITHIN 2!$!2 #     FOR INSTANCE &ROM THE OPERATIONAL (& RADAR VIEWPOINT  USE  OF THESE PROPAGATION MODELS IS LIMITED TO STATISTICAL STUDIES OF RADAR PERFORMANCE  NOT REAL 
 TERM PERFORMANCE OF EXISTING SYSTEMS &OR OPERATIONAL PERFORMANCE  CONSIDERATION OF PROPAGATION EFFECTS IS USUALLY BASED UPON A SINGLE MEASURED OR FORECASTED ATMOSPHERE SUCH THAT THESE EFFECTS CAN BE EXPLOITED OR MITIGATED BY ALTERING THE SYSTEMS USE TACTICS /VER THE YEARS  MANY PROPAGATION MODELS HAVE BEEN DEVELOPED TO ACCOUNT FOR THE EFFECTS IMPORTANT TO A PARTICULAR APPLI 
 ERROR DETECTOR 'ENERALLY  THIS EFFECT IS NEGLIGIBLE BECAUSE THE CROSS 
 ( a) Bulk Carrier with four times magniﬁcation. ( b) Container Ship. ( c) Oil Tanker. 
 Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation. 26.8  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 A simple relationship between a duct’s thickness and its ability to trap a particular  frequency is given by  ld max. .. 
 )&&$(#!+/!-.  1 )**&!, 1 ),  (#!  .$(# ,$##!,-,$##!,- ), !-. /&-! 
 202-211, December. 1957.  48. 
 The AGC results in a constant angle sensitivity independent of target size and range  With AGC the output of the angle-error detector is proportional to the difference srgrlal  normalized (divided) by the sum signal. The output of the sum channel is constant.  Hybrid tracking system. 
 Thus, the  improvement factor will be limited to 40 dB if 2 p∆f T = 0.01 rad, where ∆ f is the  oscillator frequency change between transmitted pulses and T is the transit time of   the pulse to and from the target. FIGURE 2.72  Phase instability ch02.indd   66 12/20/07   1:45:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 CHANNEL ROTARY COUPLER 4HE TRANSMITRECEIVE ISOLA 
  INTERFERENCE RATIO ARE DESCRIBED ON PP  AND   AND THE EQUATIONS FOR CALCULATING THE CONTRIBUTION FROM NOISE JAMMING BARRAGE OR RESPONSIVE  ARE DESCRIBED ON P  #!20%4 IS PROGRAMMED IN #    AND HAS A 7INDOWS 80 
 For a more complete treatment of this topic, the reader is referred to Battan.10 Wilson and Brandes57 give a comprehensive treatment of how radar and rain-gauge data can be used to complement one another in measurements of precipitation over large areas. Bridges and Feldman58 discuss how two in- dependent measurements (reflectivity factor and attenuation) can be used to obtain both parameters of the drop-size distribution and therefore precisely determine the rainfall rate. Seliga and Bringi59 show how the measurement of Z at horizontal and vertical polarization also can produce two independent measurements and therefore provide more accurate rainfall rate measure- ments. 
 The transmission utilizes two time-sequenced  LFM pulses of different frequencies in order to create Swerling Case 2 target statistics.  Both radars employ frequency-domain digital pulse compression processing. Air Surveillance and Precision Approach Radar System. 
 Hanssen, Radar Interferometry , Dordrecht, The Netherlands: Klewer Academic  Publishers, 2001. 46. H. 
 Deflection-modulated CRTs, such as the A-scope, generally  employ electrostatic deflection. Intensity-modulated CRTs, such as the PPI, generally employ  electromagnetic deflection.  Magnetically focused tubes utilize either an electromagnet or a permanent magnet around  RECEIVERS. 
 It is not practical to use such a mount, therefore, for tracking targets through the zenith,  as in the tracking of satellites. The rearrangement of the two axes as in (c) takes care of this  problem. Tracking through the zenith is possible without encountering impractical drive  accelerations. 
 Miuol\'Cll'e J..vol.12,pp.75--80.December, 1969. 46.Querido. H.J..J.Frank.andT.Cheston: WideBandPhaseShirters.IEEE Trans.vol.AP-15.p.300. 
 The signal re -received over the signal path is fed into a frequency dependent filter,  according to Figure 8.19e.  The first arriving low frequency f1 is delayed around t2, and the . Radar System Engineeri ng Chapter 8 – Pulse Radar  63     later, higher frequencies delayed only around t1. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.636x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 with terminated elements to form a rectangular aperture for purposes of minimizing  antenna radar cross section. All active components are accessible from the rear for ease  of maintenance aboard ship. 
 19.31  Radome  .............................................................  19.32 . This page has been reformatted by Knovel to provide easier navigation. 
 OUT 
 The likelihood ratio is an important statistical tool and may be  defined as the ratio of the probability~<lcnsity function correspori<ling to signal-plus-noise.  Psn(1·). to the probability-density function of noise alone, Pn(v). 
 On the basis of a single sweep, moving targets cannot be distinguished from fixed  targets. (It may be possible to distinguish extended ground targets from point targets by the  stretching of the echo pulse. However, this is not a reliable means of discriminating moving  from fixed targets since some fixed targets can look like point targets, e.g., a water tower. 
 1959.  82. Hlake, L. 
 Ryan, “Analysis of electromagnetic propagation over variable terrain using the parabolic  wave equation,” Naval Ocean Systems Center TR-1453, October 1991. 18. A. 
 Thus the nonlinear target cross section  depends on the power, and the normal radar equation does not apply. In one system formula-  tion the range dependence varied as the sixth power instead of the fourth power.50 High peak  power is more important with such targets than is high average power.  Similar techniques have also been proposed for cooperative targets by deliberately pro-  viding the target with a passive transponder employing microwave  diode^.^^*^^  Another related target effect that might be utilized for target recognition is the random  modulation of the scattered signal caused by the modification of the current distribution on  a metal target that results from intermittent contacts on the target.67 This modulation can  be detected by examining the frequency spectrum in the vicinity of the received carrier. 
 PROCESSING GROUP 4HE DATA 
 Ashley, J. R., T. A. 
 8 * 
 General Often used for  high-speed   target capability  ( Mach 1).   Extremely wide  bandwidths  achievable.Use is generally  restricted to applications  where primary   target radial velocities  < Mach 1. Multiple  tuned matched filters  are generally not  computationally  practical.Generally found in  low doppler shift  applications.Generally found in  low doppler shift  applications. 
 MANCE TO BE DESIGNED FOR RADARS IN THE (& AND 6(& BANDS $OUBTLESS  FUTURE COMPONENTS WILL EXTEND THIS PERFORMANCE TO HIGHER 2& FREQUENCIES    "7 
 CENTERED#ARTESIAN %ARTH 
 83-87, April. 1977.  66. 
  REFLECTOR ANTENNA SHOWN IN  &IGURES  AND   HAVE ALSO BEEN USED TO ENABLE SHAPED BEAMS AND LOW SIDE 
 Computations are not required as in other mounts. The antenna may be rotated at  constant rates higher than would be practical with other mounts requiring application or a  correction for a variable platform-lilt. This three-axis stable base antenna has no elevation  angle and is limited to applications which scan the horizon or a fixed angle or elevation with  respect to the horizon. 
 TRACKING ERRORS  SIMILAR TO TARGET 
 Steinberg, B. Radar imaging from a distorted array: The radio camera algorithm and experiment. IEEE T rans. 
 'O  The output of the matched filter may be shown to be proportional to the input signal  cross-correlated with a replica of the transmitted signal, except for the time delay tl. Thc  cross-correlqion function R(t) of two signals y(A) and s(A), each of finite duration, is defined as  The output yo(t) of a filter with impulse response h(t) when the input is yi,(t) = s(t) + rt(t) is  If the filter is a matched filter, then h(A) = s(tl - A) and Eq. (10.17) becomes  Thus the matched filter forms the cross correlation between the received signal corrupted by  noise and a replica of the transmitted signal. 
 E. M. T. 
 RELATIVE CLUTTER SPECTRAL SPREAD afT FIG. 15.19 Reference curve of optimum average SCR improvement for a gaussian-shaped clutter spectrum. NUMBEROFPULSESINMIT-N FIG. 
 0- PoSition ofsink·" Reference pointis. waveguide flangeFigure6.7Rieke,orload,diagram forthe SFD-341 coaxialmagnetron. Dutycycle= 0.0009,peakcurrent=24A,pulsewidth= 2.25ps,frequency =5.65Gliz.(Courtesy VarianAssociates, Inc.,BelJerly, MA.). 
 R.: Doppler Navigation. chap. 6 of "Avionics Navigation Systems," M. 
 With a  sufficiently low VSWR, the magnetron operation will not occur in either the sink or the  antisink region, no matter what the phase angle of the load.  I Reference point is .  waveguide flange Figure 6.7 Rieke, or load, diagram for the  SFD-341 coaxial magnetron. 
 13.12). 31any deviations from Fig. 12.1 arepossible ifthetimer provides the synchronizing pulse. 
 10.6 PERFORMANCE OF THE RADAR OPERA TOR  J  The rate of information inherent in a typical radar signal is considerably greater than can be  handled by a human operator. A one-me,ahertz-bandwidth signal, for example, is capable of  conveying information at a rate of two megabits/s, but an operator can accept an information  rate of only 10 to 20 bits/s. Thus there is a tremendous mismatch between the information  content of a radar and the information-handling capability or an operator. 
 The position of the display  cursor is always available in a data box in terms of range and bearing from own ship  and/or latitude and longitude coordinates. It is this cursor that is used to select and de- select targets within the operational display area and to draw user-defined maps. It is  also commonly used to set range and bearing markers. 
 Apin-jack test point is provided atthegrid ofVstoaidinaligning thediscriminator, and another atthe plate ofVsforchecking the control signals tothethyratron. This AFC unit requires apower source supplying 5maat+300 volts, 23.5 maat+105 volts, 2maat–300 volts, 1.55 amp at6.3volts, and 0.8 amp at6.3volts at—225 volts from ground. N’one ofthese voltages needs toberegulated, although the plate voltages must bewell filtered. 
 (ILL "OOK #OMPANY     2 , #OSGRIFF  7 ( 0EAKE  AND 2 # 4AYLOR  h4ERRAIN SCATTERING PROPERTIES FOR SENSOR SYSTEM  DESIGN v 4ERRAIN (ANDBOOK ))  #OLUMBUS 4HE /HIO 3TATE 5NIVERSITY  %NG %XP 3TA !NTENNA  ,AB     2 + -OORE  h2ADAR SCATTERING CROSS 
 PULSE FEEDBACK CANCELER &OR THE CANCELERS SHOWN  THE IMPROVEMENT FACTOR CAPABILITY OF THE THREE 
 Functions may be interchanged if the sign of the parameter t is reversed. Examples are pairs 6 and 7 obtainable from pairs 2 and 4 with the substitution of T s for B Hz. Taylor time weighting is applied in pair 7 to achieve good frequency resolution when the coefficients are selected for a specified sidelobe level. 
  4EC3!2  4HE FIRST SPACE 
 [CrossRef ] 8. Zhang, L.; Lu, Z.; Ding, X.; Jung, H.S.; Feng, G.; Lee, C.W. Mapping ground surface deformation usingtemporarily coherent point SAR interferometry: Application to Los Angeles Basin. 
 Geophys. Res ., vol. 93, pp. 
   
 TIME 
 4.8, the first blind speed 11, IS  plotted as a function of the maximum uniimbiguous range (Rundmb = c7/2), with radar  frequency as the parameter. If the first blind speed were 600 knots, the maximum unambiguous  range would be 130 nautical miles at a frequency of 300 MHz (UHF), 13 nautical miles at  3000 MHz (S band), and 4 nautical miles at 10,000 MHz (X band). Since commercial jet  aircraft have speeds of the order of 600 knots, and military aircraft even higher, blind speeds in  the MTI radar can be a serious limitation. 
 Each type of antenna has its particular advantages and limitations. Generally, the larger the  antenna the better, but there can be practical constraints that limit its size. 1.2 TYPES OF RADARS Although there is no single way to characterize a radar, here we do so by means of  what might be the major feature that distinguishes one type of radar from another . 
 TEMS 4HE EXTENSIVE USE OF DIGITAL SIGNAL PROCESSING OF RADAR DATA HAS RESULTED IN A DEMAND FOR CONVERTERS WITH BOTH STATE 
 ARRAYS  IS APPLIED WITH A SET OF WEIGHTS FOR THE SUM AND A DIFFERENT SET OF WEIGHTS FOR EACH DIFFERENCE CHANNEL 4HIS IS SCHEMATICALLY ILLUSTRATED IN &IGURE  FOR A UNIFORM LINEAR ARRAY 5,!  THAT GENERATES A SUM AND A DIFFERENCE CHANNEL 4HE FIGURE DEPICTS A 5,! WITH  RECEIVING ELEMENTS CLUSTERED INTO FOUR NOT OVERLAPPING AND NOT REGULAR SUB 
 The behavior of antennas both within lossy dielectrics and over lossy  dielectrics is well reported. The propagation of electromagnetic pulses in a homoge - neous conducting earth has been modeled by Wait27 and King,28 and the dispersion of  rectangular source pulses suggests that the time-domain characteristics of the received  pulse could be used as an indication of distance. The interaction between the antenna and the lossy dielectric half space is also sig - nificant as this may cause modification of the antenna radiation characteristics both  spatially and temporally and should also be taken into account in the system design. 
             (d) Figure 2. Results of the four methods. 
 Feeds for an offset paraboloid must be aimed beyond the center of the reflector area to account for the larger space taper on the side of the dish away from the feed. The result is an unsymmetrical illumination. The corners of most paraboloidal reflectors are rounded or mitered as in Fig. 
 ............  15  Noise  ................................ ................................ 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 predominantly to waves whose velocities are fairly closely matched to the wind veloc - ity and undergo redistribution across wavenumber space through the mechanism of  nonlinear wave interactions to preserve the equilibrium spectral form. 
 472–484, 1970. 46. B. 
 1985 ,132, 45–57. [ CrossRef ] 17. Zhu, X.; He, F.; Ye, F.; Dong, Z.; Wu, M. 
 The ratio by which the targ~t echo power may be weaker than the  coincident clutter echo power and still be detected with specified detection and false­ alarm probabilities. AIi target radial velocities are assumed equally likely. A subclutter  visibility of, for example, 30 dB implies that a moving target can be detected in the  presence or clutter even though the clutter echo power is 1000 times the target echo . 
    $           !! "!        "!! . 
 Î°£{  2!$!2 (!.$"//+  FACTORS FOR THE $0#! MAIN 
 HAND 7HEN    \  B \   n  THE POLARIZATION IS ELLIPTICAL !NALYTICALLY  THE ELECTRIC FIELD MAY BE DESCRIBED AS  %    %HH   %VV    WHERE H AND V ARE UNIT VECTORS IN THE  H AND V DIRECTIONS 4HE INSTANTANEOUS FIELDS ARE  GIVEN BY %Q   WHERE THE  DS SHOW THE DIFFERENT PHASES FOR THE COMPONENTS OF  %  AND K IS THE WAVENUMBER   ET % EHHJT K XH   2E 
 Since the requirements ofthe actual transmission and reception are very similar tothose oftelevision, slightly modified television transmitters and receivers can beused. Together with the antennas, etc., they will bereferred toasthe“radio-frequency” (r-f) equipment. The remaining components will becalled the “terminal” equipment. 
 In particular, range ambiguities will occur for ranges having a difference given by A/? = Y (21.50) where T is the interpulse period. To date, systems have been built which have avoided ambiguities by virtue of . illuminating only the part of the ambiguity diagram that excludes all but one ma- jor peak. 
 IEEE T rans. Geosci. Remote Sens. 
 Garbacz and D. L. Moffett, “An experimental study of bistatic scattering from some small,  absorber-coated, metal shapes,” Proc. 
 61, pp. 1218–1227, 1977.  99. 
 Pieralace et at al. [ 3] presents a new simple and very effective ﬁltering technique, which is able to process full-resolution SAR images. Gambardella at al. 
 That istosay, inatime short compared with l/(B, itisextremely unlikely that the output power will change noticeably. 1On the other hand, during atime long compared with l/01, fluctuations will almost certainly occur, and thevalue ofthepower Pattheend ofsuch along time will bear nosystematic relation atalltothevalue ithappened tohave atthe beginning. This isaroundabout way ofsaying that values ofPdeter- mined attimes differing bymuch more than 1/6 arestatistical yinde- pendent, or,inother words, I/@ isameasure ofthecorrelation time ofthe fluctuations. 
 STATE TRANSMITTER AND A VACUUM TUBE TRANSMITTER WHEN DETERMINING WHAT TYPE OF 2& POWER SOURCE TO USE IN ANY PARTICULAR APPLICATION 4HE CHOICE BETWEEN THE TWO SHOULD BE MADE BY COMPARING A RADAR SYSTEM DESIGNED TO EFFECTIVELY USE SOLID STATE AND A RADAR SYSTEM DESIGNED TO EFFECTIVELY USE VACUUM TUBES !SSUMING THE SOLID STATE AND VACUUM TUBE RADARS ARE  DESIGNED TO PROVIDE IDENTICAL PERFOR MANCE FOR THE DESIRED  APPLICATION  THEN THE CHOICE SHOULD BE BASED ON COMPARING COST  SIZE  WEIGHT  RELIABIL 
 i  The microwave radar that uses the over-ocean evaporative dlrct (Sec. 12.5) to obtain  extended propagation to detect low-altitude or surface targets beyond the normal line of sight  is also sometimes called an over-the-horizon radar. It should not be confused wit11 the HF  radars described in this section that operate at much lower frequencies and at much longer  ranges. 
 Feedsupport. Theresonant half-wave dipoleandthewaveguide horncanbeattanged tofeed theparaboloid asshowninFig.7.9aandb.Thesetwoarrangements areexamples ofrear feeds.Thewaveguide rearfeedshowninFig.7.9bproduces anasymmetrical patternsincethe transmission lineisnotinthecenterofthedish.ArearfeednotshownistheCutlerfeed,9a dual-aperture rearfeedinwhichthewaveguide isinthecenterofthedishandtheenergyis madetobend1800attheendofthewaveguide byaproperly designed reflecting plate.Therear feedhastheadvantage ofcompactness andutilizesaminimum lengthoftransmission line. Theantenna mayalsobefedinthemannershowninFig:7.9c.Thisisanexample ofa frontfeed.Itiswellsuitedforsupporting hornfeeds,butitobstructs theaperture. 
 M.: Ballistic-Missile Defense Radars, IEEE Spectrum, vol. 7, pp. 32-41, March, 1970. 
 Serafin, and L. C. Peach: Uncertainties in Coherent Measure- ment of the Mean Frequency and Variance of the Doppler Spectrum from Meteorolog- ical Echoes, Preprints, 15th Conf. 
 14.2  Noise in Sources  ...............................................  14.3  Noise from Clutter  ..............................................  14.3  Microphonism  .................................................... 
 The longer gravity waves require a finite time to build up and reach  saturation: hence, the wind alone might not be a true measure of sea conditions unless account  is taken of the length of time and the distance (fetch) over whic11 the wind has been blowing.  Thus radars at the lower frequencies which are more responsive to the longer gravity waves  might experience a value of <r0 that does not seem responsive to the immediate value or wind  speed. Another complicating factor is tile breaking or waves and the generation of spray, foam,  or whitecaps which have an effect on the radar backscatter. 
 radar right targets inside the 5 mile range marker are clearly visible. On the 3 cm. radar left the close range targets are missing. 
 Since the frequency  excursion Af is inversely proportional to range, the radar is better operated at very low  altitudes in the more normal manner with a fixed AJ and hence a varying beat frequency.  Measurement errors. The absolute accuracy of radar altimeters is usually of more importance  at low altitudes than at high altitudes. 
 116 HOW RADAR WORKS  the frequencies of operation are so high that they bear  some relation to the speed of the electrons travelling  from cathode to anode of the valves. In a normal valve  on normal wavelengths the familiar theory of operation  takes for granted the fact that the electrons emitted by  the cathode, controlled by the grid, and attracted to the  anode will have time to make the journey and do their  job. Indeed, in normal working the electrons travel  with the speed of light, approximately, and one does not  have to consider, say, placing the anode very close to the  filament to ensure that the electrons will have time to  make the journey before the next half-cycle of oscillation!  But in centimetric radar that is precisely our problem. 
 It placed responsibility on the launching nation to (1) conduct safety tests and evaluations consistent with international standards; (2) provide the United Nations with detailed design and test data of the NPS at launch time; and (3) when reentry of the NPS becomes reasonably certain, provide the United Na- tions with details of orbiting parameters, probable impact regions, power history, inventory of nuclear fuel, and radiation dosage at 1 m for survival sections. The working group noted that U-235-fueled reactors required 400 years' decay time to reduce fission product activity by a factor of 1000. It implied that a minimum or- bit altitude of 300 nmi should be used. 
 October, 1955.  38. Withers, M. 
 OMETER SHARE ELECTRONICS #OMBINED INSTRUMENT MASS IS  ^ KG  AND REQUIRED PRIME  POWER IS ^ 7&)'52%    4HE 3EAWINDS SCATTEROMETER   AS EMBARKED ON *APANS !$%/3 
 SEC INTEGRATION TIME OF THE RETURNS !NTENNA GAIN IS  D" !VERAGE DATA RATE IS  KBITSS $YNAMIC RANGE IS  D" MINIMUM DETECTABLE VOLUMETRIC RETURN IS n D": 4HE 02 MASS IS  KG INPUT POWER REQUIRED IS  7 0EAK POWER TRANSMITTED IS  K7 4HE #02S HIGH 
 The clamps oneach ofthe amplifier grids ofFig. 13.46 are ofthe double-triode variety illustrated inFig. 13.25a. 
 The outputs from more than one radar or the outputs from each beam of a stacked­ beam radar may be displayed on the same CRT in different color, as can alphanumeric data  or symhols. Color can be an "attention-getter," and can improve the accuracy of recognition.  l n an MTI radar with a synthetic-video display that presents only moving targets, the clutter  that is rejected (the raw video) can be superimposed on the display by showing it in a  different color than the synt hct ic-video targets. 
 IOI. Hajovsky. R. 
 J. T.: Helix and Coupled-Cavity Traveling-Wave Tubes, Proc. IEEE. 
 7. Fry. I). 
 TACT  BUT THEY DID DETECT THE SPLASHES MADE BY SHELLS HITTING THE WATER .OTHING WAS EVER FOUND 7HEN 53 AND #ANADIAN FORCES LANDED AT !TTU ON !UGUST TH  THEY FOUND THE ISLAND ABANDONED 4HE   *APANESE TROOPS HAD BEEN EVACUATED UNDER COVER OF FOG AND RAIN ON *ULY TH ,ATER INVESTIGATION DETERMINED THAT THE *APANESE EVACUATION   
 A third component, the vertical velocity, is needed  and may be provided from some nondoppler source such as a barometric rate-of-climb meter.  The primary advantage of the two-beam system is a reduction in equipment. However, the  accuracy is not as good as with systems using three or four beams. 
 THE 
 9.6 or they may be used as receiver protectors. For example,44 a  VHF balanced duplexer configuration using 32 PIN diodes mounted in 3t inch coaxial line (16  in each of two SPST shunt-type limiters) handled 150 kW peak power, 10 kW average power,  with a pulse width of 200 µs. At the frequency of operation (200 to 225 MHz), the use of  self-actuated diodes was practical. 
 POWER MICROWAVE RADAR TUBES CAN ACHIEVE  TO  BAND 
 , vol. 65D, pp. 427–432, 1961. 
 Multiple CPIs (at different PRFs and perhaps at different RF frequencies) improve detection and can provide information for true radial velocity determination.23 The design of the individual filters in the doppler filter bank is a compromise between the frequency sidelobe requirement and the degradation in the coherent integration gain of the filter. The number of doppler filters required for a given length of the CPI is a compromise between hardware complexity and the strad- dling loss at the crossover between filters. Finally the requirement of providing a high degree of clutter suppression at zero doppler (land clutter) sometimes intro- duces special design constraints. 
 [ CrossRef ] 10. Ivanov, A.Y.; Ginzburg, A.I. Oceanic eddies in synthetic aperture radar images. 
 PLE THAT THE DISCRETE &OURIER TRANSFORM $&4  OF THE TIME CONVOLUTION OF TWO SEQUENCES  IS EQUAL TO THE PRODUCT OF THE DISCRETE &OURIER TRANSFORMS OF EACH OF THE SEQUENCES )F  - RANGE SAMPLES ARE TO BE PROVIDED BY ONE PROCESSOR  THE LENGTH OF THE $&4 MUST EXCEED - PLUS THE NUMBER OF SAMPLES IN THE REFERENCE WAVEFORM MINUS ONE TO ACHIEVE  AN APERIODIC CONVOLUTION 4HESE ADDED  - SAMPLES ARE FILLED WITH ZEROS IN THE REFER 
 Mooney, D. H., and W. A. 
 A typical performance in sidelobe jamming when the jamming  level varies by 20 dB per pulse is shown in Figure 7.17. By employing a second test to  FIGURE 7.13  Implementation of a binary integrator. The letter C indicates a comparison. 
 TIDs may have wavelengths of hundreds of kilometers and speeds up to  1000 kilometers per hour. Unless the radar makes appropriate real-time corrections to  the target coordinates, tracking accuracy will be severely impaired. To address these various needs, it is advantageous to adopt corresponding descrip - tions or models, emphasizing different aspects of the ionosphere and its influence on  radiowave propagation and, hence, HF radar performance. 
 28Thermal Noise Power • Consider a receiver at the standard temperature , Todegrees Kelvin (K).   Over a range of frequencies of bandwidth Bn(Hz) the available noise  power is  where                              (Joules/K) is Boltzman's constant. • Other radar components will also contribute noise (antenna, mixer,  cables, etc.). 
 Clearly, the relative phase between the two polarizations is an essential  factor for two of the four Stokes parameters. Data expressed through the Stokes param - eters are well-suited to being exploited by matrix decomposition methodology.60,117 For a given transmitted polarization, the values of these Stokes parameters are  invariant with respect to the polarization basis of the receiver. It follows that the opti - mum architecture is hybrid-polarity118: circularly polarized on transmit and linearly  dual-polarized on receive (Figure 18.17). 
 Zrnic, “Weather radar polarimetry: Trends toward operational applications,” Bull. Amer.  Meteorol. 
 J., and L. Moskowitz: A Proposed Spectral Form for Fully Developed Wind Seas Based on the Similarity Theory of S. A. 
 ARRAY PERFORMANCE MAINLY IN TERMS   OF TARGET TRACKING UNDER %#- 4HE SIMULATION BENCHMARK  INCLUDES TWO TYPES OF  %#-  NAMELY 3/* AND 2'0/ 4HE 3/*  MOUNTED ON AN AIRCRAFT  TRANSMITS BROADBAND NOISE TOWARD THE RADAR 4HE 3/* FLIES AN OVAL RACE COURSE  HOLDING PATTERN IN A CLOCK 
 Gladman: Further Observation on the Detection of Small  l'argets in Sea Clutter, Tire Radio ut~d Electronic Etrginecr, vol. 45, pp. 105--I 15, March. 
 Oneoftltelimitations ofadielectric lensistheproblem ofremoving heatdissipated withintheinterior. Dielectrics aregenerally poorconductors ofheat.Unlessmaterials areof lowlossandcanoperate atelevated temperatures,63 dielectric lensessuchastheLuneburg lensaremoresuitedtoreceiving, ratherthantransmitting, applications. TheLuneburg principle mayalsobeappliedtoatwo-dimensional lenswhichgenerates a fanbeaminoneplane.Inthegeodesic analogofatwo-dimensional Luneburg lensthe variation indielectric constant isobtained bytheincreased pathlengthfortheRFenergy traveling intheTEMmodebetween parallelplates.64--67Theresultisadome-shaped parallel­ plateregionasshowninFig.7.22. 
 ING THE RECEIVED SIGNALS  U  V  WITH THE HYPOTHESIS  ( WHEN THE TRUE HYPOTHESIS IS  (  0&! IS A FUNCTION OF THE DETECTION THRESHOLD  @ NORMALIZED TO THE NOISE POWER LEVEL AND  OF THE BLANKING THRESHOLD  & III  4HE PROBABILITY  0$ OF DETECTING A TARGET IN THE MAIN  BEAM  WHICH IS THE PROBABILITY OF ASSOCIATING THE RECEIVED SIGNAL  U  V  WITH ( WHEN  THE SAME HYPOTHESIS IS TRUE  0$ DEPENDS  AMONG OTHER THINGS  ON THE SIGNAL 
 This isaspectacular advance inpulse-radar technique but itdoes not entirely eliminate the clutter problem. Itisapplicable only to moving targets, and then only when theunwanted echoes from the sur- roundings donot fluctuate sorapidly astodefeat the pulse-to-pulse comparison which isanessential part ofthescheme. Another direction from which the clutter problem can beattacked isthat ofresolution. 
 J. Campbell: Experimental Results of the  t'omplcx lntlic;~tcd Aiiglc 'I'ccliniqt~c for Mitltipath Correction, IEEE 7'rntu., vol. AES-10, pix  779 787. 
 PASS OR BANDPASS DEPENDING ON THE APPLICATION $ELTA 
 SUM MEASUREMENTS FROM MULTIPLE TRANSMITTER 
 The image data presented in Figure 14.25 were collected for a stepped-frequency  signal with a bandwidth of 2.1 GHz centered at 3.4 GHz. The aspect angle was varied  over a sector 35 ° wide centered on the nose-on aspect. The charted image contours are  5 dB apart and the total amplitude variation is 30 dB. 
 16.S.—Cmcellation ofsignals ofcon- Animportant practical point inthe stant pulse-to-pulse phase. use ofthis scheme isthedegree to which theoutput signal ofthe delay line simulates the input signal,’ for the fidelity ofreproduction ofsignals bythe delay line influences the maximum clutter cancellation possible. Ibisalso possible todelay the signals bymeans ofa“storage tube, ” which works inamanner related tothat ofthe Iconoscope used in television. 
 MacArthur, C. C. Kilgus, C. 
 TEM  GIVING RISE TO NULLS ALONG DIRECTIONS DIFFERENT FROM THOSE OF THE JAMMERS   4HE TRADEOFF THAT HAS TO BE SOUGHT BETWEEN THE ACCURACY OF WEIGHTS ESTIMATION AND  THE REACTION TIME OF THE ADAPTIVE SYSTEM  4HE LIMITED NUMBER OF TIME SAMPLES AVAILABLE TO ESTIMATE THE JAMMER COVARIANCE  MATRIX USUALLY .  SAMPLE SHOULD BE AVAILABLE IF  . IS THE NUMBER OF ADAPTIVE  CHANNELS  4HE ANTENNA ROTATION RATE THAT MIGHT PRODUCE A FAST TIME VARYING POWER AND  JAMMER $O! *OINT 3," AND 3,#  3," IS EFFECTIVE AGAINST SPIKY SIGNAL AFTER PULSE COMPRES 
 .~[\ i . .r 1·'~t!'!;J ::;'1--;::. -~  , rr .. 
 21, no. I, pp. 30-34, Junc/July, 1975. 
 A modulator with an internal impedance of 150 ohms will result in  both current and voltage variations as a function of frequency when used with the above CFA,  but the power output varies only 1 dB. Thus it does not matter significantly to the modulator  designer whether the CFA is of the backward-wave or the forward-wave type as long as  cathode pulsing is used with either a line-type modulator or a constant-current hard-tube  modulator.  Electron emission in high-power crossed-field amplifiers can take place by cold-cathode  emission without a thermally heated cathode. 
 Each station had tobechecked and calibrated both forheight and azi- muth byanelaborate and difficult series oftest flights. The complicated nature ofthe corrections necessary oneach aircraft plot, and therequirement forspeed and accuracy inapplying these cor- rections, ledthe British todesign and install what isperhaps the first device intended forassistance intheuseofradar data, asopposed tothe gathering and display ofthat data. This isthe celebrated “fruit machine, ”lacomplicated calculating machine made upofstandard telephone selector switches and relays. 
 The major distinction between meteorological radar and other kinds of radars lies in the nature of the targets. Meteorological targets are distributed in space and occupy a large fraction of the spatial resolution cells observed by the radar. Moreover, it is necessary to make quantitative measurements of the received sig- nal's characteristics in order to estimate such parameters as precipitation rate, precipitation type, air motion, turbulence, and wind shear. 
 RADAR CLUTTER 485  made to decorrelate the two pulses received from a target with the high-speed rotation rate by  transmitting each of the two pulses'at a different frequency. Unexpectedly, no discernible  improvement was noted when the two frequencies were used instead of a single frequency, even  though the two frequencies were 60 MHz apart. This would indicate that there is a slowly  fading component of the clutter echo which cannot be decorrelated and is probably similar to  the clutter spikes discussed in Sec. 
 378-381. May, 1976.  102. 
 TERS  THE FEED IS HEAVY BECAUSE IT MUST CARRY HIGH POWER AT LOW LOSS !%3! FEEDS USE  SMALLER COAX  STRIPLINE  MICROSTRIP  OR 2& MODULATED LIGHT IN FIBER OPTICS FOR TRANSMIT  AND RECEIVE 2&  SINCE LESS THAN  WATTS 2& OR OPTICAL IS USUALLY REQUIRED (OWEVER  SIGNIFICANT $# POWER IS STILL REQUIRED FOR 2& FEED DISTRIBUTION AMPLIFIERS BECAUSE THOU 
 [ CrossRef ][PubMed ] 19. Li, S.Y.; Zhu, B.C.; Sun, H.J. NUFFT-Based Near-Field Imaging Technique for Far-Field Radar Cross Section Calculation. 
 Therefore, the sensitivity  of the FM-CW receiver described here is degraded and the ability to operate with multiple  targets is usually poor. For a radio altimeter whose target is the earth, these limitations usually  present no problem. When used for the long-range detection of air targets, for example, the  nonoptimum detection of the classical FM-CW radar will seriously hinder its performance  when compared to a properly designed pulse radar. 
 RIC RADARS PROVIDES AN IMPORTANT DATA SET FOR CLIMATE CHANGE STUDIES AS WELL AS MONI 
 The pixel units in azimuth direction are equally spaced according to the rotation angle ( θ) of the ArcSAR system, and there are N pixel units in this direction. The Rs-axis of the coordinate system represents the range direction. The pixel units in this direction are equally spaced according to the slant range ( Rs), and there are M pixel units in this direction. 
 TO 
 BORNE   NAVAL 
 Atmos. Ocean. Technol. 
 Dither-tuning of a coaxial magnetron may also be obtained by a mechanical tuning  element called a ring tuner. 5•6 This consists of a narrow ring installed in an annular groove cut  into the outer wall of the cavity. The ring projects slightly into the cavity. 
 The model uses three parabo- las to approximate the electron distribution with altitude. Electron density and . FREQUENCY, MHz FIG. 
 4.23, is sometimes called a coherellt integratio11 filter.  To generate the N filters simultaneously, each of the taps of the transversal filter of  Fig. 4.11 would have to be divided into N separate outputs with separate weights correspond- Ill  'O ::,  a. 
 This direct-current component will beafunction of azimuth angle and so,asthesystem scans, wefind atthesecond detector output that is,direct current plus various “varying direct current’ ‘— low-frequency components extending up toamaximum frequency roughly given bythe reciprocal ofthe time the beam isonthe target. But theground returns aresoenormous compared totarget signals that one might fear that even the tails ofthe ground-return frequency spec- trum would belarge compared with the desired signals. Actually, this fear isnot realized, aswill beshown byabrief calculation. 
 Inanother variation, advantage istaken ofthe fact that thecold (i.e., nonoscillating) impedance ofcertain types ofmagnetrons is such astobeabad mismatch tothe line, sothat nearly allthe power coming toward the magnetron isreflected. Then the ATR switch can beomitted ifthe line length between the magnetron and T-junction is chosen correctly. This isknown as“pre-plumbing.” With many types ofmagnetron itisnot feasible. 
 CONSTANT &4#  DEVICES PERHAPS OF LITTLE USE IN MODERN RADAR   AUTOMATIC GAIN CONTROL !'#   AND #&!2    (OWEVER  THEY CANNOT BE SAID TO BE %##- TECH 
 On transmit, nulls can be placed in the direction  of high ground clutter to reduce the clutter power reflected back toward the antenna.  Active arrays typically have both amplitude and phase control at each element, which  allows either full amplitude and phase nulling or phase-only nulling to be used.  However, when transmitting, it is desirable to have uniform illumination across the  aperture to produce the highest aperture efficiency possible. 
 SPECTRAL OR CORRELATION PROCESSING TECHNIQUES 3INCE  THE MEASUREMENT IS MADE IN PAIRS OF OVERLAPPING BEAMS DIRECTLY ABOVE THE RADAR  IT IS NO LONGER NECESSARY TO ASSUME OR REQUIRE HORIZONTAL HOMOGENEITY OF THE WIND FIELD IN THE LARGER AREA ABOVE THE RADAR ANDOR THE LONG INTEGRATION TIMES NECESSARY TO ASSURE THIS HOMOGENEITY 4HESE SPACED ANTENNA TECHNIQUES ARE MOST FREQUENTLY USED WHEN HIGH SPATIAL AND TEMPORAL RESOLUTION MEASUREMENTS ARE REQUIRED SUCH AS ESTIMATING DETAILED BOUNDARY LAYER TURBULENCE FIELDS :HANG AND $OVIAK HAVE INVESTIGATED USING THE DUAL BEAMnSPACED ANTENNA TECHNIQUE IMPLEMENTED WITH AN ELECTRONICALLY SCANNED PHASED ARRAY RADAR TO ESTIMATE THE TRANSVERSE  AS WELL AS THE R ADIAL  WIND COMPONENTS  AT ARBITRARY SCAN ANGLES . 
 H The toroid. or twin-slab. ferrite phase shiner may be operated in an analog  fashion hy varying the current of the drive pulse so as to provide different values of remanent  magnetization. 
 These arethe solid lines whose form suggests hyperbolas; they show the. SEC. 10.4] PERFORMANCE CHARTS ANDRIEKE DIAGRAMS 337 pulse r-fpower which isobtained under varying input conditions. 
 Meteorol., vol. 38, pp. 741–749, 1999. 
 FERS INCREASED SIDELOBE CLUTTER LEVELS 4HE FLOODLIGHT RECEIVER REMEDY CAN BE USED BY A HITCHHIKER TO FLOOD A SECTOR SCANNED BY THE TRANSMIT BEAM  AGAIN RESTORING THE SUR 
 98 INTRODUCTION TO RADAR SYSTEMS  signals orthogonal. The MRA 5 operates within the 10 to 10.5 GHz band, from 100 m to  50 km range with an accuracy of ±0.05 m ± 10-5 d, assuming a correction is made for  meteorological conditions.  In addition to its use in surveying, the multiple CW frequency method of measuring range  has been applied in range-instrumentation radar for the measurement or the distance to a  transponder-equipped missile;65 the distance to satellites;66 in satellite navigation systems  based on range measurement;67 and for detecting the presence of an obstacle in the path of a  moving automobile by measuring the distance, the doppler velocity, and the sign or the  doppler (whether the target is approaching or receding).63  REFERENCES  l. 
 30. Dunn, J. H., and D. 
  THREE 
 ACCELERATIONS &ILTER COVARIANCES ARE NOT EXACT DUE TO NONLINEAR TRANSFORMATION %XTENDED DUAL COORDINATE +ALMAN FILTER 0OLAR #ARTESIAN %ARTH 
 The radar  video is passed through a threshold detector, which may be thought of as a bottom clipper.  Only those signals whose amplitude exceeds the preset threshcld are allowed to pass. This is  the first of two thresholds, hence the name double-threshold detector which is sometimes used. 
 BASED AND  LINEAR FREQUENCY MODULATION TERMS  &IGURE  SHOWS THE FREQUENCY MODULATION 
 Roberts, J. H. G.. 
 range = 2 nmi. The Rayleigh distribution is  shown for comparison. Dashed curve shows attempt to fit the sea state 2-3 data to log-normal distrihu-  tion. 
 Thus, onacentered PPI, the fundamental pulse-length resolution and the spot-size resolution are equal when 12.2R/T =180, orR=15when r=1.Accordingly, on asetwith al-psec pulse, a15-mile centered PPI will have thefullinherent range resolution; a100-mile PPI will reduce itapproximately sevenfold, and soon. This reduction inresolution can beovercome bythe use of expanded displays, but often this measure restricts the field ofview. Fortunately for the indicator designer, however, this isnot the entire story. 
 In Sec. 10.2 it was  shown that the frequency-response function of the matched filter was given, except for a  constant and a time delay, by  S*(J) H(J) = ----------I N;(J) 12 .) ( 11. l I )  where in the notation of Sec. 
 The other two geometries show a similar but broader forward-scatter lobe, as is ex- pected since the silhouette area and hence the shadowing aperture are smaller. The 45° aspect geometry is of interest because the RCS in the bistatic region is larger than the monostatic RCS for most bistatic angles. The large spike at P = 90° is the bistatic specular lobe, analogous to the monostatic specular lobe in the broadside geometry. 
 Aerial type Type of sortieNo. of targetsAv. recorded range, milesAv. 
 35.Schneider, A.:Oversea RadarPropagation WithinaSurface Duct,IEEETrans.,vol.AP·17, pp.254-255, March,1969. 36.Hitney,H.V.:RadarDetection RangeUnderAtmospheric Ducting Conditions, IEEE1975-/lltema· tionalRadarConference, Arlington, Va.,pp.241-243, iEEEPublication 75CHO938-1AES. 37.Katzin,M.,R.W.Bauchman, andW.Binnian: 3-and9-Centimeter Propagation inLowOceanDucts, Proc.IRE,vol.35,pp.891-905, September, 1947. 
 MENTS IN OPTIMUM AMPLITUDE DISTRIBUTION FOR SUM AND DIFFERENCE PATTERNS EXIST   BUT   AS WITH OTHER ANTENNA SYSTEMS  THEY MAY BE INDEPENDENTLY SATISF IED 4HE SUM AND DIF 
   05,3% #/-02%33)/. 2!$!2   n°£Ç BETWEEN n AND n IN ACCORDANCE  WITH THE SEQUENCE OF ELEMENTS  S AND  S OR  S AND  
 Itissignificant that the most important practical application ofc-w radar has been made inthis field. 4.4. Clutter.-One ofthe most formidable limitations tothe useful- ness ofpulse radar until recently was that imposed by“clutter.” Often aradar system sees too much, rather than too little; the picture iscon- fused byunwanted echoes, orclutter. 
 Gassner, P. Hull, P., J. Mason, and J. 
  FILTER WOULD BE COMPOSED OF A DECIMATE 
 The Direct Digital Synthesizer15 (DDS) produces  waveforms using digital techniques and provides significant improvements in stabil - ity, precision, agility, and versatility over analog techniques. The main limitations are  the noise and spurious signals as described below. The general DDS architecture is  shown in Figure 6.24. 
 SPACE WAVELENGTH4!",%  "ANDWIDTH #RITERIA FOR 3EVERAL &EED .ETWORKS .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°{Î THESE NETWORKS ARE EXPENSIVE AND LOSSY AND CONTAIN ERRORS !N ALTERNATIVE IS TO USE A  BROADBAND BEAM 
 54. J. D. 
 The RF frequency of the Varian SFD-354A  X-band coaxial magnetron can be varied sinusoidally over a 60-MHz range at a rate of 70  times per second by this method.  RADAR TRANSMITTERS 199 1\measure oftheeffectoftheloadonthemagnctron frequency istheplIlIi"gfigure. defined asthedifference between themaximum andminimum frequencies whenthephase angleoftheloadvariesthrough .1600andthemagnitude oftheVSWRisfixedat1.5(ora rdlcction coefficicnt of0.20).Thepullingfigurcisreadilyobtained fromaninspection ofthe Riekediagram. 
 HALF 
 The noise power contribution correspond - ing to this segment is found as  PS ff f all S f=⋅+⋅ −≠ − ⋅+ + 1 121 11 1 11 11αα α ααα [ln n() ln()] f f2 1 1 − =−   α (2.44) Table 2.4 gives the integration for the example. When the integrated powers for all  segments have been calculated, they are summed and then converted back to dBc. The  final answer, −66.37 dBc, is the limit on I that results from oscillator noise. 
 20.3/?. For a radar located near the surface of the earth, it can be readily shown from the law of cosines that, to a first approximation, hT = ha + RT sin 97 + RT2/2R0 (20.2) where r() is the radius of the earth and the other parameters are as defined above. The height calculated with the above curved-earth algorithm exceeds that cal- culated by using the flat-earth algorithm, increasing quadratically with measured target range. 
 P. Schlesinger, and C. M. 
 GUIDE MODELS ARE NOT GENERALLY USED FOR ASSESSMENT SYSTEMS REQUIRING RAPID EXECUTION TIMES 7AVEGUIDE MODELS SERVE AS hLABORATORY BENCHMARKv MODELS AGAINST WHICH THE RESULTS OF OTHER MODELING TECHNIQUES CAN BE COMPARED /NE SUCH  WAVEGUIDE MODEL IS  THE -,!9%2  DERIVED FROM THE ORIGINAL WORKS OF "AUMGARTNER  0ARABOLIC %QUATION -ODELS  )N   &OCK USED THE PARABOLIC EQUATION 0%   METHOD TO DESCRIBE ELECTROMAGNETIC PROPAGATION IN A VERTICALLY STRATIFIED TROPOSPHERE )N   (ARDIN AND 4APPERT  DEVELOPED AN EFFICIENT PRACTICAL SOLUTION CALLED THE SPLIT 
 Matched Filtering.  Although matched filtering is typically now performed  within the digital signal-processing function, the concept is explained here for com - pleteness. The overall filter response of the system is chosen to maximize the radar  performance. 
 STATE TRANSMITTER WAS BUILT FOR THE .AVAL 3EA 3YSTEMS #OMMAND BY THE THEN  7ESTINGHOUSE %LECTRIC #ORPORATION  4HE EXISTING WAVEFORM FROM THE ORIGINAL TRANSMITTER WAS NOT CHANGED   AND THE SOLID 
 If the noise samples have a non-Rayleigh density such as the chi-square density or  log-normal density, it is necessary to estimate more than one parameter and the adap - tive detector is more complicated. Usually two parameters are estimated, the mean  and the variance, and a threshold of the form T K= +ˆ ˆµ σ is used. The sampled mean  is easily obtained. 
 H.: Passive Remote Sensing at Microwave Wavelengths, Proc. IEEE, vol. 57, pp. 
 ABLY NEED MULTI 
 Trans- mission via tropospheric scatter can also be used in special cases.50 In all these direct time synchronization schemes, implementation is straightforward, much like the initial synchronization process in communication systems. They can also be used for any type of transmitter pulse repetition interval (PRI) modulation: stable, staggered, jittered, and random. With time synchronization established, target range is calculated via Eq. 
 The diag o- nal elements contain the frequency response error.  The elements c12, c21, c34 and c43 result from . Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 99     the final polarization purity of both orthogonal channels. 
 All parameters associated with a given track are referred to by this track number.  Typical track parameters are the filtered and predicted position; velocity; acceleration  (when applicable); time of last update; track quality; signal-to-noise ratio; covariance  matrices (the covariance contains the accuracy of all the track coordinates and all the  statistical cross-correlations between them), if a Kalman-type filter is being used; and  FIGURE 7.24 b Thirty-minute time lapse of tracks formed from data   in Figure 7.24 a, using Global Nearest-Neighbor (GNN) Technique ( after   H. Leung et al.38 © IEEE 1999 ) ch07.indd   23 12/17/07   2:13:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 POINT &&4S /NE SCHEME WOULD BE TO ENSURE THAT THE COMPUTATION STAGES CARRY ENOUGH BITS TO ACCOMMODATE THE BIT 
 DIMENSIONAL SURFACE SLOPES REQUIRED FOR USE 
 In the millimeter-wave region, the drop sizes of the raindrops span both the Rayleigh and the  Mie scattering regions so that a difference in behavior can be expected. Experimental measure-  ments indicated that, on the average, the radar backscatter at 9.4 and 35 Gtfr appeared to  follow the Rayleigh scattering  la^.^^.'^^ Deviations from Rayleigh were found at 70 and  95 GHz, and the backscatter at 95 GHz was observed to be less than at 70 GHz. The back-  scatter at. 
 REFLECTOR DESIGN SHOWN IN  &IGURE  WORKED TOLERA BLY WELL FOR SMALL  TEST TARGETS  BUT IT SOON BECAME APPARENT THAT THE REFLECTOR HAD TO BE CONSIDERABLY LARGER  FOR MANY TARGETS OF VITAL MILITARY INTEREST 4HIS COULD BE ACCOMPLISHED BY DOUBLING OR TRIPLING THE SIZE OF THE REFLECTOR  BUT THAT BROUGHT ON A ROUND OF OTHER PROBLEMS  MAINLY THE INCREASED FOCAL LENGTH OF THE REFLECTOR 7HILE THE FOCAL DISTANCE COULD BE SHORTENED TO COMFORTABLY FIT AXIAL SPACE LIMITATIONS ALONG THE BORESIGHT OF THE REFLECTOR   IT WAS THEN HARDER TO CONTROL THE FIELD AMPLITUDE TAPER ACROSS THE REFLECTOR DUE TO THE PROXIM 
       )0     0 D"M 0 D"M 0 D"M 0 D"MFF F F     
 Appl. P/1\·s., vol. 26. 
 The weights of the tubes alone are compared in Table 4.1; however, the solenoid required for high-power linear-beam tubes and their higher voltages usually make linear-beam-tube transmitters considerably heavier than CFA trans- mitters. Size. The same comments apply as noted under "Weight." Cost. 
 S. O. Rice, “Reflection of electromagnetic waves by slightly rough surfaces,” Commun. 
 The envelope of the spectrum is determined by the pulse shape. For the rectangular pulses usually employed, a (sin x)lx spectrum is obtained. The received spectrum from a stationary target has lines that are doppler- shifted proportionally to the line of sight, or radial velocity, between the radar platform and the target. 
 OFF IS THAT ADJACENT AREAS ALONG 
 Nathanson, Radar Design Principles,  2nd Ed. New York: McGraw-Hill, Inc., 1991,   pp. 120–123. 
 CRAFT  AND MISSILES  NAVIGATION BUOYS  AND OTHER TARGETS SHARING THE RADAR RESOLUTION CELL WITH THE SEA SURFACE 4HESE INTERFERING SIGNALS ARE COMMONLY REFERRED TO AS  SEA  CLUTTER  OR  SEA ECHO 4HE SEARCH FOR A USEFUL UNDERSTANDING OF THIS IMPORTANT RADAR  CONTAMINANT BEGAN WITH THE COLLECTION AND ANALYSIS OF CLUTTER DATA FROM OPERATING RADARS  WITH THE GOAL OF  ESTABLISHING THE RELATIONSHIP BETWEEN  CLUTTER SIGNALS AND THE  PARAMETERS OF BOTH THE RADAR AND THE SEA ENVIRONMENT -UCH OF THE EARLIEST WORK TOOK PLACE DURING 77)) AND CAN BE FOUND IN ONE OF THE COMPREHENSIVE SERIES OF 2!$,!" VOLUMES DOCUMENTING THE RADAR RESEARCH THAT WAS DONE AT THAT TIME  "UT  MOST OF THE CLUTTER DATA FROM THIS PERIOD  AND EVEN INTO THE S  WAS COLLECTED IN BITS AND PIECES FROM ISOLATED EXPERIMENTS  OFTEN WITH POOR  INCOMPLETE  OR MISLEAD 
 In principle, the cross-section fluctuations might be able to provide  some information that can distinguish one type of target from another. If the target is rotating,  as were some of the early unstabilized satellites, the amplitude fluctuations of the radar cross  section with time can provide information from which the shape of the target can be  determined. 60 It has also been suggested that the complex echo-signal fluctuations (amplitude  and phase) can be employed for target classification.65 . 
 In Proceedings of the 1st International Conference on Image Processing, Austin, TX, USA, 13–16 November 1994; pp. 910–914. 24. 
 4152,   pp. 110–119, 2000. 30. 
 Other methods of using Butler  tietworks in planar arrays are possible. Shelt~n,~' for example, describes a technique for  generating multiple beams in hexagonal planar arrays with triangular spacing.  The Butler networks in this section were assumed to use 3-dB directional coiiplers with a  90" phase difference between the two equal outputs. 
  
 The combination of STC with enhanced high-angle coverage does  quite well for insects and birds, but does not eliminate automobile and truck returns.  Vehicles have RCSs that equal or exceed the RCS of many desired aircraft targets. Technique 3. 
 REFLECTION MULTIPATH AND &ARADAY ROTA 
  
 In fact, only a single, relatively small, physical antenna is used in most cases. In considering a synthetic aperture, one makes reference to the characteristics of a long linear array of physical antennas. In that case, a number of radiating elements are constructed and placed at appropriate points along a straight line. 
 Target Doppler.  When the transmitter and receiver are stationary ( VT = VR = 0),  the target’s bistatic doppler at the receive site fB is  fB = (2V/l ) cos d cos (b /2) (23.9)FIGURE 23.5.  Block diagram of a typical Earth-based system used for downlink bistatic radar. 
 Rept. 7977, March 16, 1976. 15. 
 J. Applegate: Radar Backscatter from Land, Sea, Rain. and Snow at  Millimeter Wavelengths. 
 420 R-FCOMPONENTS [SEC. 11.10 ingminimum items bemounted inagroup and that thegroup beasnear theantenna aspractical: 1.Pulse transformer. 2.Magnetron. 
 Inthissection, several possible radartechniques thatmightbeusedfortargetclassification willbeenumerated briefly.Generally, targetclassification byradarinvolves examining the detailed structure oftheechosignal.·Itusuallyrequires alargersignal-to-noise ratiothan normally neededfordetection.' Thustherangeatwhichtargetclassification canbemadeis oftenlessthantherangeatwhichthetargetcanbefirstdetected. High-range-resoludon. Ashort-pulse. 
 24.28, January, 1966.  41. Boxer, A. 
 RECEIVER SYSTEMS   /UT 
 G. Vane, “The CloudSat mission,” in Proceedings IEEE International  Geoscience and Remote Sensing Symposium , Toulouse, France, 2003. 152. 
 The eight pat- terns in Fig. 11.12 were measured with the plane of the aperture tilted above or below the line of sight by the angle c|>. The broad central part of these patterns is due to a triple-bounce mechanism be- tween the three participating faces, while the "ears" at the sides of the patterns are due to the single-bounce, flat-plate scattering from the individual faces. 
 The design of low cross-section vehicles probably began when  Clarence (“Kelly”) Johnson, Lockheed’s famous designer, undertook development FIGURE 14.28  RCS of a collection of bodies of revolution of similar size and  projected area ( after W. E. Blore68 © IEEE 1964 ) ch14.indd   39 12/17/07   2:47:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 P. M. Thompson, R. 
 This  permits sensitivity time control (STC) to be used with the radar without a loss of coverage at  high altitudes and short range (Fig. 7.27). The STC is employed to reduce near-in clutter,  especially from birds and insects. 
 Luscombe, E. J. Langham, and S. 
 While the binary integrator performs this type of CFAR action, analysis24'25 has shown that the ratio detector in Fig. 8.14 is a better detector. The ratio detector sums signal-to-noise ratios and is specified by n 2 / *\ S-r-= — (8-17) 5^§fo2(/+i+*) + *,-2C/-l-*)] where X1(J) is the /th envelope-detected pulse in the Jth range cell and 2m is the number of reference cells. 
 STORMS RESULT FROM SOLAR FLARES AND  CORONAL MASS EJEC 
 7.20.  Another class of metal-plate lens is the constrained lens, or path-length lens, in which the  rays arc guided or constrained by the metal plates. In the H-plane metal-plate constrained  le11s. 
 McBride, Jr.: Methods of Increasing Bandwidth of High Power  Microwave Amplifiers, IRE WESCON Conv. Record, vol. 1, pt. 
 Since signal voltages from the detector may be20volts ormore, the output voltage must belimited sothat the indicator will not bedriven outside itsallowable range ofvoltage. The simplest and most commonly used type ofvideo amplifier isthe resist ante-capacitance-coupled am-6+ plifier shown inFig. 12.10. 
 How the additional influences  of the fluctuation loss affect the radar range  tendentiously?               4. The transmitters pulse width of pulse d radar is 1 .5 µs and the duplexers recovery time is  0.5 µs. How far -off the antenna an airplane must be located at the least as to be detecting  by  the radar?    . 
 Briefly, the most common problems are as follows:FIG. 4.4 Coaxial magnetron. (From Ref. 
 TION  THE TRANSMIT SIGNAL MUST START AT THE SAME PHASE ON EVERY PULSE /THERWISE  THE   &)'52%   $IRECT $IGITAL 3YNTHESIZER $$3    . 
 power point conforms closely to mean sea level. The in­ strument tracks the location of that point with respect  to the transmitted pulse, and the height measurement  is telemetered to the ground. The slope of the leading  edge directly affects the measurement precision and de­ grades performance with increasing wave height. 
 The  available gain G is equal to S0u1/Sin, k Boltzmann's constant = 1.38 x 10-23 J/deg.  T0 = standard temperature of 290 K (approximately room temperature), and Bn is the noise  bandwidth defined by Eq. (2.3). 
 AP-17, pp. 381-384, May, 1969.  36. 
 Bucy, “New results in linear filtering and prediction theory,” J. Basic Eng .  (ASME Trans ., ser. 
 Additionally, many military radar systems include a sidelobe blanker  or several sidelobe canceler channels to combat jamming. Since the advent of digital  beamforming radar systems, the number of receiver channels required has increased  dramatically, with some systems now requiring hundreds of receiver channels. In  these multichannel receiver systems, close matching and tracking of gain and phase is  required. 
 A direct method for determining roughness is to observe the scatter from the ob- ject with a resolution that can resolve the roughness scale. Other Target Measurements. Just as the radial velocity can be determined from the temporal doppler frequency shift, it is possible to measure the tangential (cross-range) component of velocity. 
 TURE LENGTH GENERATED DURING A TARGET DWELL 3TIMSON EXPLAINS h4YPICALLY  THE ANTENNA  CONTINUOUSLY SCANS THE REGION OF INTEREST"ECAUSE THE INTEGRATION TIME IS LIMITED TO THE LENGTH OF TIME A GROUND PATCH  IS IN THE ANTENNA BEAMOR  IF  YOU PREFER  THE LENGTH  OF THE ARRAY THAT CAN BE SYNTHESIZED IS SO LIMITEDTHE RESOLUTION IS COARSER THAN CAN BE ACHIEVED WITH A NON 
 Burg. It works well with a Howells- Applebaum adaptive beamformer, which has an omnidirectional receiving pattern  except where jammers are present. The presence of jammers is indicated by nulls in  the receiving pattern. 
 surface erosion. and the constant flexing of the material in the wind. In high  winds the rliatcrial car1 he daniaged by flying debris and the rotation of the antenna might have  to cease to prevent the fabric from being blown against the antenna and torn. 
 Skolnik, Introduction to Radar Systems , 3rd Ed., New York: McGraw-Hill, 2001. 124. H. 
 FREQUENCY SURFACE 
 FIGURE USUALLY REQUIRES A BIAS CONDITION THAT IS CLOSER TO THE PINCH 
 Radford. M. t-., and R. 
 Locating thejammer mightnotbeasimportant, however, aslocating theattacking missiles oraircraftscreened bythejammer, especially whenthejamming aircraft isbeyondthe rangeofdffcnsive weapons. Ajammer thatoperates outside therangeofnorm~1 defenses is knownasasta/ld-of/jammer. Animportant ECCMtacticistoengagehostilejammers with !roml'-OII-jam (IIOJ)missileguidance. 
 , vol. 100,   pp. 15117–15127, 1995. 
 Blass beam-forming arra~·. 8 5 The RF beam-forming principle shown in Ftg. 8.26 has been  used in the At~illR-1. 
 The other is the d([l'raction region, which lies beyond the line  or sight. or beyond the horizon, of the radar. Radar energy found in this region is usually due  to diffraction by the curvature of the earth or refraction by the earth's atmosphere. 
 Each RF power tube has its own peculiar characteristics which determine the  particular type of modulator to be used. The magnetron modulator, for instance, must be  designed to handle the full pulse power. On the other hand, the full power of the klystron and  the traveling-wave tube can be switched by a modulator handling only a small fraction of the  total beam power, if the tubes are designed with a modulating anode or a shadow grid. 
 If the gain of each receive antenna is made equal to the gain of the initial single  receive antenna, range performance is also restored. However, this remedy increases  the cost and complexity of the receiver since a special beamforming network is  required, along with a receiver and signal processor (RSP) for each beam. The multi - beam receiver can be used with any type of transmitter, including a floodlight transmit - ter where the loss in range performance might be offset by an increase in dwell time  on target, as detailed subsequently. 
 196 INTRODUCTION TO RADAR SYSTEMS  (4) load susceptance. The first two parameters are related to the input side of the tube, whik  the last two are related to the output side. In most magnetrons the magnetic field is fixed by the  tube designer and may not be a variable the radar designer has under his control. 
 For example, FTC allows the detection of signals that are greater than clutter  by preventing the clutter from saturating the computer. FTC does not provide sub - clutter visibility. AGC keeps the radar receiver operating within its dynamic range,  preventing system overload and providing proper normalization so as to furnish sig - nals of standardized amplitude to radar range, velocity, and angle processing-tracking  circuits. 
           . 
 Baynton et al.,49 Wilson and Roesli,50 and Serafin1 all show how modern meteorological radars are used for forecasting the weather. The degree to which automation can be applied is evident in the NEXRAD radar system design, where the meteorological products shown in Table 23.7 will be automated.51 TABLE 23.7 NEXRAD Automated Products Doppler radar data archive of storm phenomena Precipitation analysis Wind analysis Tornado analysis Fine-line analysis Tropical cyclone analysis Mesocyclone analysis Thunderstorm analysis Turbulence analysis Icing analysis Hail analysis Freezing-melting analysis Interpretive techniques Multiple-radar mosaics Precipitation Measurement. Among the more important parameters to be measured is rainfall, having significance to a number of water resource management problems related to agriculture, fresh-water supplies, storm drainage, and warnings of potential flooding. 
 4.10. The pulse-doppler mode of operation has the further advantage in  that each beam can operate with a single antenna for both transmitter and receiver, whereas a  CW radar must usually employ two separate antennas in order to achieve the needed isolation.  fjdwever, pulse systems suffer from loss of coverage and/or sensitivity because of "altitude  holes." These are caused by the high prf commonly used with pulse-doppler radars when it is  necessary to achieve unambiguous doppler measurements. 
  
 In this situation the radar is assumed to track continuously or "searchlight" a target for an interval of time tQ. Equation (1.5) applies, so that the tracking-, or searchlighting-, radar equation is 4 /V0G, Aev " max 4TTkT0Fn(EINo) where Pavf0 = Et. Thus, in a tracking radar that must "see" to a long range, the average power must be high, the time on target must be long, and the antenna must be of large electrical size (G,) and large physical size (Ae). 
 Thus the radar antenna is called upon to fulfill reciprocal but related roles. In  the radar equation derived in Chap. 1 [Eq. 
 Inthe electrostatic tube shown, the electrons achieve their final velocity before reaching the deflecting plates. Insome tubes designed for high-voltage use, deflection sensitivity isincreased byapplying. SEC. 
 .ATHANSOHN AND 5 .AFTALY  h/VERVIEW OF THE 4%#3!2 SATELLITE MODES OF OPERATION v  IN 0ROCEEDINGS  TH %UROPEAN #ONFERENCE ON 3YNTHETIC !PERTURE 2ADAR   $RESDEN  'ERMANY  6$%  6ERLAG    9 7U  - :HU  AND 7 (ONG  h3!2 ACTIVITIES IN 0 2 #HINA v IN  0ROCEEDINGS OF %53!2  $RESDEN   'ERMANY  )4' 6$%  .   30!#% 
 The pulse-width discrimination circuit measures the width of  each received pulse. If the received pulse is not of approximately the same width as  the transmitted pulse, it is rejected. A pulse-width discrimination technique can help  in rejecting chaff; in fact, echo returns from chaff corridors are much wider than the  transmitted pulse. 
 SCATTERING  SECTION WILL BE LARGER WHEN THE POLARIZATION VECTOR IS IN LINE WITH THE PIPE 4HIS MEANS THAT ANY AREA THAT IS SURVEYED WITH  SAY  PARALLEL DIPOLES MUST BE SURVEYED IN ORTHOGONAL DIRECTIONS TO ENSURE THAT NO TARGETS ARE MISSED 4HE SAME REQUIREMENT ALSO RELATES TO CROSSED DIPOLE ANTENNAS Ó£°Ê **  /" - )T IS ONLY POSSIBLE TO PROVIDE A BRIEF SUMMARY OF THE WIDE VARIETY OF THE APPLICATIONS FOR '02  WHICH HAS IN SOME CASES BECOME AN ESTABLISHED AND ROUTINE METHOD OF SUB 
 For example, itmay berequired that itrespond toweak pulses even inthe presence ofac-w signal ofconsiderable strength. The problem of detecting aweak target echo inthepresence ofstrong seareturn issome- what similar. Special circuits which gounder thegeneral title of“anti- clutter circuits” areusually required insuch cases. 
 33. Spencer, R. C., and G. 
 BANDWIDTH PRODUCT  COMPRISED OF THE ILLUMINATION TIME OF THE TARGET  AND ITS DOPPLER  BANDWIDTH 3UBSTITUTING FOR DOPPLER  BANDWIDTH IN THE UNDERSPREAD CONDITION LEADS TO  THE CONSTRAINT  42 . R2,A 3!Z !Z     WHICH  SHOWS HOW RESOLUTION AND TARGET ILLUMINATION TIME MAY BE TRADED AGAINST EACH  OTHER WHILE STILL RESPECTING THE FUNDAMENTAL AMBIGUITY CONSTRAINT 4HE FOLLOWING FOUR  CASES ARE IMPORTANT IN PRACTICE 3TRIP -AP 4HE STANDARD APPROACH IS STRIP MAPPING  IN WHICH THE AMBIGUITY 
 STATE 'AIN 2ELATION AND  4RACKING )NDEX 4UNING -ETHOD #HARACTERISTICS -ODEL NO  #ONSTANTLY ACCELERATING TARGET WITH  A WHITE NOISE JERK  J ;GS  (Z= SAMPLED BY RADAR  MEASUREMENT *ERK IS THE RATE OF CHANGE OF ACCELERATION    J444 444 444KKK KKK KK K      3TEADY 
 13.45). When amplifiers are used, orifanelectrostatic tube without amplifiers isinvolved, theresolver must deliver sawtooth voltages into a high-impedance load; when amagnetic tube isused without amplifiers, sawtooth currents must bedelivered toaninductive load. Inprinciple the resolver may beasynchro, apotentiometer, ora condenser; asynchro isfarthemost satisfactory and, inspite ofcertain shortcomings, itisuniversally used. 
 PULSE FREQUENCY OR PHASE JITTER )N ADDITION  THE  SYSTEM MUST SUCCESSFULLY OPERATE IN AN ENVIRONMENT THAT COMPRISES MANY UNWANTED TARGETS  SUCH AS BIRDS  INSECTS  AND AUTOMOBILES (ARDWARE #ONSIDERATIONS  )N THIS SECTION  RULES AND FACTS RELATING TO -4) RADAR  DESIGN  AS DEVELOPED DURING MANY YEARS OF WORK IN THE FIELD  WILL BE SUMMARIZED 4HE RULES ARE AS FOLLOWS  /PERATE AT CONSTANT DUTY CYCLE  3YNCHRONIZE AC 
 Atmospheric·turbulence as well as deliberate maneuvers result in the aircraft trajectory . OTHER RADAR TOPIC'S ,2J  deviating from a straight line. These deviations must be sensed and proper compensation  applied to the received~signal phase so-as to "straighten uut""the syntheticantenna.19 The  required phase correction is a function of range with the more rapid corrections required at  steep depression angles. 
 MTIorpulse-doppler radarisalsonecessary inradarcarried byhigh-nying aircraftthatmustdetectotheraircraftmasked byseaclutter. Although shipsaremovingtargetsthatmightbecandidates forMTIradar,itisnotoften thatMTIisneededforthisapplication. Thelargecrosssectionofshipsgenerally resultsin suitah1c target-to-clutter ratioswithconventional radars. 
 SECONDS  MKS  UNITS ARE USED  THE CALCULATION OF  : WILL HAVE DIMENSIONS OF MM #ONVERSION  TO THE MORE CONVENIENT UNITS OF MMM REQUIRES THAT  : BE MULTIPLIED BY THE FACTOR   &URTHERMORE  EXPRESSING  0R AND R IN COMMON UNITS OF D"M D" RELATIVE TO  MILLIWATT   AND KM REQUIRES THAT  : ALSO BE MULTIPLIED BY  "ECAUSE  : VALUES OF INTEREST CAN RANGE  OVER SEVERAL ORDERS OF MAGNITUDE  A LOGARITHMIC SCALE IS OFTEN USED 4HUS  D " :   #   0 R D"M     LOG R KM    . £°È  2!$!2 (!.$"//+  WHERE # ISOLATED IN BRACKETS IN %Q   IS THE SO CALLED 7EATHER 2ADAR #ONSTANT  WITH 0R EXPRESSED IN D"M AND  R IN KM 4YPICAL VALUES OF  # ARE  TO  D" FOR THE  OPERATIONAL WEATHER RADARS )T IS CLEAR THAT FOR FIXED RANGE AND RECEIVED POWER  A LOWER VALUE OF THE RADAR CONSTANT  # ALLOWS A SMALLER REFLECTIVITY VALUE IN D": TO BE OBSERVED  4HUS  SMALLER VALUES OF # CORRESPOND TO MORE SENSITIVE RADARS 4HIS EQUATION CAN BE USED TO MEASURE THE REFLECTIVITY FACTOR  : WHEN THE ANTENNA  BEAM IS FILLED  WHEN THE SMALL SCATTERING PARTICLE 2AYLEIGH APPROXIMATION IS VALID  AND WHEN THE SCATTERERS ARE IN EITHER THE ICE OR THE WATER PHASE "ECAUSE ALL THESE CONDI 
 BEAM CLUTTER REGION IS AT ZERO VELOCITY AND THE SIDELOBE CLUTTER REGION FREQUENCY BOUNDARIES VARY SINU 
 In both cases, the  total number of filter zeros is assumed to be equal to 3. For the adaptive MTI with a  fixed allocation of zeros, two zeros are located at zero doppler and the remaining zero  is centered on the chaff returns. In the optimum MTI, the zero locations are chosen  so that that overall improvement factor is maximized. 
 Details of typical sampling receivers, which are essentially  the same as sampling oscilloscopes, can be found in the literature, and once issues of  sampling linearity in time are addressed, the generic design has formed the basis for  the majority of commercial GPR systems. A key parameter for most GPR systems is the mean power. The time-domain radar  transmits, on a repetitive basis, a short duration impulse. 
 Some of the electrons emitted from the cathode  are not collected by the anode but return to the cathode by the action of the RF field and the  crossed electric and magnetic fields. When these electrons strike the cathode they produce  secondary electrons that sustain the electron emission process. Cold-cathode emission requires  the presence of both the RF drive signal applied to the tube as well as the d-c voltage between  cathode and anode. 
 5X.Morgan. S.P:General Solution oftheLuneburg LensProblem, J.Appl..Pllys.,vol.29. pp.135R1368.September. 
 Collins, G. W.: Shaping of Subreflectors in Cassegrain Antennas for Maximum Aperture Efficiency,  IEEE Trans., vol. AP-21, pp. 
 Thus thedrop across Risgiven by E–E, +E&=E– E,(l– G). 512 THERECEIVING SYSTEM—INDICATORS [SEC, 13.10 ascompared toE–E=were the feedback not present; theeffect ofthe amplifier isthe same asthat ofusing asupply voltage E/(1 –G). For atriode, 1/(1 –G)may beasmuch as20,and forapentode asmuch as200. 
 69] EARLY AIRCRAFT-WARNING RADAR 177 energy was radiated backwards tomake ituncertain, without special arrangements, whether atarget was infront oforbehind astation. The main receiving antenna consisted ofapair (ora stack ofpairs) ofcrossed dipoles, mounted on240-ft wooden towers. Balanced pairs ofconcentric feeders connected thedipoles tothefield coils ofagoniom- eter whose rotor ~vas connected tothe receiver. 
 DETECTABLE 
 Direct time syn- chronization methods can be used for this task. Alternatively, the stable clocks can be slaved to a second source, such as Navstar GPS or loran c.50'82'130 Indi- rect time synchronization can also be employed with a dedicated or cooperative transmitter using random PRIs if a random code sequence is established a priori and is known by the receive site. In direct time synchronization, the required clock stability between updates is, to a first order, AT/JM, where AT is the required timing accuracy and Tu is the clock update interval. 
 Bickrnore, R. W.: A Note on the Effective Aperture of Electrically Scanned ~rra~s, IRE Trans.,  vol. AP-6, pp. 
 . VALUE  SELECTING THE DETECTIONS  BASED ON THE MINI 
 RATE SAMPLING USING MINIMUM 
 For this purpose, a highly directive (narrow) beam width is needed, not only to achieve angular accuracy but also to resolve targets close to one another. This important feature of a radar antenna is expressed quantitatively in terms not only of the beamwidth but also of transmit gain and effective receiving aperture. These latter two parameters are proportional to one another and are directly related to the detection range and angular accuracy. 
 1945, but 200 were kept in reserve and assessment by ASWDU continued in case the tactical situation changed [ 5]. 4.4.3 Indicating unit type 162C This indicating unit was similar to indicating unit 162B used on ASV Mk. VIA and is illustrated in ﬁgure 4.19. 
   30!#% 
 5.15, therefore, thesignals ‘“)~ Contain thefrequencyjrarelike those ofFig. 5’17b, and donot l.-2r/c iThe signals are now passed through (b) ;-~;-m””mafull-wave rectifier, thevoltage atPoint 3inFig. 5.15 being like Fig. 
 ING ALGORITHMS FOR 3"2 3!2 DATA $ATA 0RODUCTS  4HE NOTIONAL DATA PRODUCT FROM A SPACE 
 is measured in meters,.fp in Hz, and the relative velocity in  knots, the blind speeds are , ,  The blind speeds are one of the limitations of pulse MTI radar which do not occur with  CW radar. They are present in pulse radar because doppler is measured by discrete samples -  (pulses) at the prf rather than continuously. If the first blind speed is to be greater than the  maximum radial velocity expected from the target, the product ,Ifp must be large. 
 LEM IF THEY ARE REMOVED BY THE TRACKING SYSTEM L 3CAN 
 The results areshown qualita- tively inFigs. 5.4aand 5.4b,which aredrawn forthenormal case inwhich the frequency deviation islarge compared tothemodulation frequency. Also, only theenvelope ofthela.Ihasbeen drawn. 
 The receiver would follow the analog beamformer, as shown in  the figure. Figure 25.21 b shows an extreme application of digital beamforming, where  FIGURE 25.21  (a) Analog beamformer, ( b) every-element digital beamformer, and ( c) subarray digital  beamformerANALOG DELAY ANALOG SUMBEAMFORMER OUTPUTWAVEFRONT ARRAY ANTENNA RCVR ADC (a) (b)DIGITAL DELAY DIGITAL SUMBEAMFORMER OUTPUTWAVEFRONT RECEIVERS ADCsCLUSTER BEAMS (c)WAVEFRONT SUBARRA YS ANALOG DELAY ANALOG SUM DIGITAL DELAY DIGITAL SUMBEAMFORMER OUTPUTSUBARRA Y BEAM RCVR ADCRCVR ADCRCVR ADCRCVR ADCRCVR ADCRCVR ADCRCVR ADCRCVR ADCCLUSTER BEAMS ch25.indd   17 12/20/07   1:40:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Sensors 2018 ,18, 3750 Figure 12. InISAR imaging results of Backhoe with 25% data. ( a) Traditional imaging processing; (b) imaging processing of proposed approach (mixed Euclidean norm); complex images of channels 1 and 2 (ﬁrst and second layers); interferometric phase images (third layer); ﬁnal 3-D imaging results (last layer). 
 to the AFC unit (amplifying unit type 244) which contained a discriminator designed to output a voltage dependent on the sign and magnitude of the deviation of beat frequency from the central IF of 45 Mc/s. This voltagew a su s e dt oc o n t r o lt h er e ﬂector voltage of the local oscillator klystron, CV237, which was a low voltage re ﬂector klystron specially designed for use in AFC circuits. A local oscillator error of 15 Mc/s could be corrected to within about 0.25 Mc/s of the correct IF, for a typical local oscillator s ensitivity. 
 Mattern: Receivers. chap. 5 of" Radar Handbook," M. 
 SEC. 85] INDEPENDENCE OF INTERROGATION AND REPLY 257 Here P~iistheavailable pulse power atthebeacon forany relative posi- tion ofthe interrogator and the beacon. The gain ofthe transmitting antenna, G~,, isavariable that depends upon theangular position ofthe antenna with respect tothe line from ittothe beacon. 
 151–156. 20. H. 
 Theamount ofdifferential phaseshiftdepends ontheferritematerial andthelengthofthe toroid.Adigitallatching phaseshifterisobtained byplacing incascade anuinber ofseparate toroidsofvarying length.Thelengthsofeachtoroidareselected toprovide adifferential phase shiftofIgoo,90°,45°,22.5°,andsoforth,depending onthenumber ofbit"required. Aseparate pairofdrivewiresisusedforeachsectionoftoroid.Impedance matching isprovided atthe inputandoutputtoroids. Byfillingthecenterslotofthetoroidwithhighdielectric-constant material abetterfigureofmeritandlowerswitching powerareobtained, butthepeakpower capability isdecreased. 
 INDUCTIVE SUSCEPTANCE 4HERE ARE MANY ADDITIONAL RADOME DESIGN ISSUES AND APPLICATION SPECIFIC CONSIDER 
 FERENT hNOISEv FIELDS EG  THERMAL NOISE  SEA CLUTTER  ETC  /N THE BASIS OF THE SAMPLES  HE ESTIMATED THE STATISTICAL PARAMETERS OF THE TWO NOISE FIELDS AND THE SEPARATION POINT BETWEEN THEM 4HEN  ONLY THOSE REFERENCE CELLS THAT ARE IN THE NOISE FIELD CONTAINING THE TEST CELL ARE USED TO CALCULATE THE ADAPTIVE THRESHOLD !N ALTERNATIVE APPROACH FOR INTERFERING TARGETS IS TO USE LOG VIDEO "Y TAKING THE  LOG  LARGE SAMPLES IN THE REFERENCE CELLS WILL HAVE LESS EFFECT THAN LINEAR VIDEO ON THE THRESHOLD 4HE LOSS ASSOCIATED WITH USING LOG VIDEO  RATHER THAN LINEAR VIDEO  IS  D"   &)'52%   $ETECTION PROBABILITY VERSUS 3.2 FOR A 3WERLING #ASE  PRIMARY TARGET  AFTER * 4 2ICKARD AND ' - $ILLARD Ú )%%%  . 
 PHASED ARRAY RADAR ANTENNAS  13.516x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 13.9 PHASE SHIFTERS The three basic techniques for electronic beam steering are (1) frequency scanning,  (2) beam switching, and (3) phase scanning with phase shifters. Of the three tech - niques, the use of phase shifters is by far the most popular, and considerable effort has  gone into the development of a variety of phase shifters. Phase shifters can be sepa - rated into two categories: reciprocal and nonreciprocal. 
 For obtaining high-precision ArcSAR image, we propose interferometric DEM (digital elevation model)-assisted high precision imaging method for ArcSAR. The interferometric ArcSAR is utilized to acquire DEM. With the assist of DEM, target in scenes can be imaged on its actual height. 
 10.5 outputs of600, 200, 80,and 0.025 kw. The single anode block atthe bottom isfrom a1.2-cm 80-kw rising-sun magnetron. Figure 1020 shows one variety ofahigh-power (1000-kw output) magnetron. 
  D" AT  KM ALTITUDE )N CONTRAST TO THE SCHEME USED ON  -AGELLAN   SMALLER ANGLES OF INCIDENCE AND LOWER BANDWIDTH ARE USED FOR THE HIGHER ALTITUDES 4HE LOWER BANDWIDTH HELPS TO REDUCE THE MEAN NOISE LEVEL  WHEREAS THE SHALLOWER INCIDENT ANGLE HELPS TO MAINTAIN RANGE RESOLUTION WITH SMALLER RADIATED PULSE BANDWIDTH #LEMENTINE  ONE OF THE FIRST hFASTER BETTER CHEAPERv MISSIONS  HAD PRIMARY OBJECTIVES  INCLUDING LASER ALTIMETRY AND OPTICAL SURFACE MAPPING OF THE -OON AS WELL AS TECHNOL 
 C. Henderson, “Mixers in microwave systems (Part 1),” Watkins Johnson Company, Technical  Note, vol.17, no.1, January/February 1990.  5. 
 DENSITY MODIFICATION   AND OTHER FEATURES THAT  MAKE THE MODEL MORE GENERALLY USEFUL 4HE IONOSPHERIC MODEL AS DESCRIBED IN .2,  2EPORT  HAS BEEN USED FOR SOME OF THE EXAMPLES PRESENTED IN 3ECTION    4HE )NTERNATIONAL 2EFERENCE )ONOSPHERE )2)  IS PERHAPS THE FOREMOST MODERN EXAM 
 COLLISION  COASTAL NAVIGATION  AND PILOTAGE DECISIONS  0ILOTAGE IS NAVIGATING IN WATERS WHERE A QUALIFIED PILOT IS REQUIRED  TO BE ONBOARD  4HE FUTURE COMPULSORY FITTING OF RADAR TO SHIPS WAS CONTEMPLATED  AS WAS THE DESIRABILITY OF AN INTERNATIONALLY AGREED UPON MINIMUM  PERFORMANCE STAN 
 2017 ,14, 1–5. [ CrossRef ] 9. Chan, Y.K.; Chu, C.Y. 
 ' J   &)'52%   2ADAR INTERFEROMETRY EXPRESSES THE INTERFERENCE CREATED BETWEEN TWO MUTUALLY  COHERENT BACKSCATTERED FIELDS 4HE PHASE DIFFERENCE INTERFEROGRAM MODULO O    CORRESPONDS TO  THE RELATIVE ELEVATION OF THE ILLUMINATED TERRAIN  AFTER REMOVAL OF THE SYSTEMATIC SLANT 
 AP-12, pp. 408-417, July, 1964.  139. 
 Forward-wave CFAs, which were developed later, operate at nearly constant voltage across their frequency band and can therefore be considered for dc operation, which requires only a control elec- trode (see below) instead of a full-power pulse modulator. FIG. 4.6 Drift region and control electrode in a reen- trant CFA. 
 A. H., and J. T. 
 2. Bachynski, M. P.: Microwave Propagation over Rough Surfaces, RC A Rev., vol. 
 In a three-channel monopulse radar, all three channels are controlled by the AGC  voltage, which effectively performs a division by the magnitude of the sum signal or  echo amplitude. Conventional AGC essentially holds constant gain during the pulse  repetition interval. Also, the AGC of the sum channel normalizes the sum echo pulse  amplitude to similarly maintain a stable range-tracking servo loop. 
 U.S.Patentno.2.624.876. issuedJan.6.1953. 15.Cook.C'.E.:PulseCompression: KeytoMoreEfficient RadarTransmission. 
 New  applications are being found for radar, new systems are  being pioneered, and with almost equal suddenness  political changes take place which make some systems  of more importance than others. In radar, which spans  the globe, there can be no frontiers, and politics naturally  enter into the good-neighbour applications of radar  systems intended for international aviation and marine  transport.  During the war years we heard much of H2S, Gee,  Oboe, Babs, Eureka, Loran, and other systems. 
 A,: Ratiio Propagation over a Discontinuity in the Earth's Electrical Properties. Proi..  IEE. 
 -(Z BANDWIDTH AT COLLECTOR EFFICIENCIES GREATER THAN  %ACH MODULE IS AIR 
  +1 
 18.Kalmus, H.P.:Direction Sensitive Doppler Device,Proc.IRE,vol.43.pp.698-700. June,1955. 19.Logue,S.H.:Rate-of-climb MeterUsesDoppler Radar,Electronics, vol.30,no.6,pp.150152,Jline 1,1957. 
 S., and R. C. Srivastava: Snow Size Spectra and Radar Reflectivity, J. 
 Any use is subject to the Terms of Use as given at the website. The Radar Transmitter. 10.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 electromagnetic compatibility purposes to avoid transmitting energy beyond those  limits. This objective may be approached by using a pulse shape different from the  convenient and conventional rectangular pulse.36 Highly shaped pulses have not  been used often in radar systems because of the loss of efficiency that results. 
 Thus to understand today's systems we must understand how they became what they . are. This chapter will, therefore, begin with a discussion of the CW semiactive system and trace the evolution of the CW seeker through several generations. 
 7.5. Buildings in the vicinity of  ground-based radar, and masts and other obstructions in the vicinity of shipboard antennas  can also degrade the radiation pattern because of aperture bl~cking.'~'  -  - -  7  Figure 7.5 Effect of apcrt ure block -  ing caused by the feed in a para-  20 -15 -10 -5 0 5 10 15 20 bolic-reflector antenna. (From C. 
 In this  patent Baird stated that radio waves can be reflected  and refracted like visible light waves, and contemplated  “a method for viewing an object, consisting in projecting  1pont it electromagnetic waves of short wavelength.” In  this proposed system reflections of radio waves from an’  abject were to be passed through a ‘scanner’ to a receiver, wad the ontput of this receiver was to be used for modu-  ® See Chapter X for a detailed description.  . THE DISCOVERY OF RADAR 19  lating a source of visible light. 
 The over-all delay-line attenuation can bedivided into two parts: that which occurs inthemedium itself, and that which has todowith the efficiency ofthe quartz crystals inconverting electrical energy into acoustic energy. Both carrier frequency and tube diameter affect theattenuation that occurs within the delay medium. The free-space frictional attenuation inliquids isproportional tothesquare ofthefrequency. 
 ThetoroidphaseshifterislIollreciprocal inthatthephaseshiftdepends onthedirection of propagation. Inmostapplications thisinconvenience isusuallyaccepted inordertoachieve theotheradvantages offeredbythelatching ferritephaseshifter.Whenusedforbothtransmit andreceive, thephaseshiftmustbechanged between thetwomodesofoperation. With switching speedsoftheorderofmicroseconds, itispractical toresetthephaseshiftersjustafter transmission inordertoreceive.Theyarethenresetjustbeforetransmitting thenextpulse. 
 Oliio), pp. 133- 144. 1958. 
 PULSE BASIS MAY BE REQUIRED USING SWITCHABLE OR ELECTRONICALLY TUNED FILTERS )F THE 2& FILTERING IS LOCATED PRIOR TO 2& AMPLIFICATION  THE FILTER INSERTION LOSS WILL HAVE A D" FOR D" IMPACT ON THE RECEIVER NOISE FIGURE  ANOTHER SACRIFICE IN NOISE TEMPERATURE TO ACHIEVE MORE VITAL  OBJECTIVES 9TTRIUM IRON GARN ET 9)'  FILTERS AND PIN  DIODE SWITCHED FILTERS HAVE BEEN USED TO PROVIDE THE NECESSARY FREQUENCY AGILITY. È°£ä  2!$!2 (!.$"//+  3TRETCH 0ROCESSING  3TRETCH PROCESSING IS A TECHNIQUE FREQUENTLY USED TO PRO 
   PP n   -AY   7 # !NDERSON  h#ONSEQUENCES OF NON 
 CAL STUDIES HAVE SHOWN THAT THE MAJOR SCATTERING FEATURE UNDER THESE CONDITIONS IS THE  VERTICAL STALK THAT EMERGES SHORTLY AFTER DROP IMPACT -OREOVER  THESE STUDIES SUGGEST  THAT THE 6 
 9.4 LOW-NOISE FRONT-ENDS  Early microwave superheterodyne receivers did not use an RF amplifier as the first stage, or  front-end, since the RF amplifiers at that time had a greater noise figure than when the mixer  alone was employed as the receiver input stage. There are now a number of RF amplifiers that  can provide a suitable noise figure. Figure 9.4 plots noise figure as a function of frequency for  the several receiver front-ends used in radar applications. 
 RANGE EXAMPLE. {°ÓÈ  2!$!2 (!.$"//+  4HE AMPLITUDE OF CLUTTER RETURNS FLUCTUATE OVER TIME AND ARE MODELED AS A STOCHASTIC  PROCESS 4HE CLUTTER 
 * "9 
 The beams are  time shared by a single channel which is switched through the four-beam sequence every  94INTRODUCTION TORADAR SYSTEMS TheJanussystemcanbeoperated incoherently byusingthesametransmitter tofeeda pairofbeamssimultaneously. Typically, onebeamisdirected aheadandtotherightofthe groundtrack,andtheotheraftandtotheleft.Aforward-left andanaft-right arealsofedby thetransmitter asasecondchannel. Thetwochannels maybeoperated simultaneously or timed~shared. 
 /\ digital MTI processor does not, in prindple-;doany  helter than a well-designed analog canceler; hut it is more dependable, it requires less adjust­ ments and attention, and can do some tasks easier. Most of the advantages of a digital MTI  processor are due to its use of digital ~Ji~ rather than analog delay lines which are  characterized by variations due to temperature, critical gains, and poor on-line availability.  A simple block diagram of a digital MTJ processor is shown in Fig. 
 The magnitude operation forms (12 + Q2)112. Separate thresholds are applied  to each filter. The thresholds for the nonzero-velocity resolution cells are established by  summing the detected outputs of the signals in the same velocity filter in 16 range cells, eight  on either side of the cell of interest. 
 3.Capon,J.:Optimum Weighting Functions fortheDetection ofSampled SignalsinNoise,IEEE Trans.,vol.IT-I0,pp.152-159, April,1964. 4.Murakami, T.,andR.S.Johnson: ClutterSuppression byUseofWeighted PulseTrains,RCARev., vol.32,pp.402-428, September, 1971. 5.Emerson, R.c.:SomePulsedDoppler MTIandAMTITechniques, RANDCorp.Report 110.R-274, March,1954. 
 An example of the data stabilization is tl~e correction applied for yaw. If a PPI were to  display relative bearing (azimuth) the apparent bearing would change as the platform yawed.  With the aid of a horizontal gyroscope to provide a north reference, a correction signal can be  ohtailled which cat1 be ;~pplicd to tlic indicator to pertilit the display of the target in its true  bearing rather than the bearing relative to the platform heading. 
 This setalso went into quantity manufacture, astheSCR-268 (Sec. 6.14). AnArmy long-range aircraft- detection setwhose development had been requested earlier bythe Air Corps was demonstrated tothe Secretary ofJt’ar bythe Signal Corps Laboratories inNovember 1939. 
 Figure 2.22. Vixen on ASV Mk. II in a Wellington Mk. 
 Howells, P. W.: Explorations in Fixed and Adaptive Resolution at GE and SlJRC. /Et:£ Trnns. 
 Moroney: Microwave Mixer and Detector Diodes, Proc. IEEE, vol. 59, pp. 
 IEF.E  11011s. vol t\l:S-6. pp . 
 (ILL    P  ( 5RKOWITZ  h!NALYSIS AND SYNTHESIS OF DELAY LINE PERIODIC FILTERS v  )2% 4RANS #IRCUIT 4HEORY   VOL #4 
 Although both the elevated and the surface (evaporation)  duct can result in extended radar ranges, tlie consequences of their presence are often bad  rattier tlian good. Tlie presence of extended ranges cannot always be predicted in advance.  Furtlierniore. 
 The Bistatic  Alerting and Cueing  test program used time-multiplexed beams when hitchhiking off  the AWACS transmitter for short-range air surveillance.46,47 Pulse Chasing.  If the transmitter’s beam scanning and pulse transmission sched - ule are known, pulse chasing can be considered to reduce the multibeam cost pen - alty further.1,21,115 –118 This was successfully demonstrated in the Bistatic Radar for  Weapons Location  test program.35 The simplest pulse-chasing concept uses a single  beam and RSP that rapidly scans the volume covered by the transmit beam, chasing  the pulse as it propagates from the transmitter. The receive beam-scanning rate must  be at the transmitter’s pulse propagation rate, modified by the usual geometric condi - tions. 
 77. Dana, R. A., and D. 
 A reasonable compromise is to make the  gate width of the order of the pulse width.  A target of finite length can cause noise in range-tracking circuits in an analogous manner  to angle-fluctuation noise (glint) in the angle-tracking circuits. Range-tracking noise depends  or1 tlic lerigtli of the target and its shape. 
 314 9.22 Streamlining .... ..... ......315 9.23 Electrical Transmission. 
 14.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 14.5 RADAR ECHO SUPPRESSION The probability of being detected by hostile radars can be reduced by decreasing the  target’s radar cross section. The major methods to reduce the RCS are by shaping of  the target and the use of absorbers. By shaping, we mean the intentional selection of  target surfaces and features so as to minimize the amount of energy scattered back to  the radar. 
 58-60. May 22, 1959.  15. 
 7, pp. 55-60, May,  1977.  43. 
 DIMENSIONAL EDGE OF INFINITE  LENGTH  ILLUMI 
 The ratio 2 pa/l determines the dominant scatter - ing properties of the particle. Spherical water droplets in air that are large relative to the  wavelength scatter in the so called optical region; droplets on the order of the same size  as the wavelength scatter in the so called resonant scattering region; and droplets small  relative to the wavelength scatter in the so-called Rayleigh region. * By convention in this chapter, we shall use r for range and R for rainfall rate. 
 The ﬁrst one [ 8] is a communication describing the Imaging Multiple-Input Multiple-Output (MIMO) ground-based interferometric radar developed in order to overcome the main limitations of traditional GBSAR systems, which are based on the mechanical movement of the antenna. The proposed system reduces data acquisition time, thus both limiting the atmospheric artefacts and extending the application to vibration measurements. Moreover, the use of independent modules and integrated technologies allows reducing production costs and improving both the transportability and the deployment of the system. 
 TION ONLY OF THE SHAPE OF THE DOPPLER SPECTRUM PRIMARILY ITS SPECTRUM WIDTH  AND THE  INTEGRATION TIME  4 ALLOCATED FOR PROCESSING )F THE SPECTRUM CAN BE ACCURATELY MODELED  BY A GAUSSIAN SHAPE WITH VARIANCE  SF  %Q  REDUCES TO   VAR} F 4F S P    .OTING THAT VAR}  VAR}   VF L WE CAN WRITE  VAR} V 4V LS P   . 
 where al and a2 are the radii of curvature of the body surface at the specular point. This formula becomes exact in the optical limit of vanishing wavelength and is probably accurate to 10 or 15 percent for radii of curvature as small as 2 or 3 wavelengths. It assumes that the specular point is not close to an edge. 
 PERIOD  STAGGERING AND SCANNING ALL CANCELER FIGURATIONS   )D"     LOG ; N F   
 ING FUNCTION WILL APPLY  SO THERE SHOULD BE A CLEAR DISTINCTION BETWEEN THE UPWIND 
 The angle in a clockwise direction from this reference axis is proportional to  the distance (in wavelengths) of the standing-wave-pattern minimum from the reference point.  An advantage of the Smith chart for plotting the effects of the load on the magnetron parameters  is that the shapes of the curves are practically independent of the position of the reference  point used for measuring the phase of the VSWR.  An example of a Rieke diagram for a coaxial magnetron is shown in Fig. 
 Sci.) 2017 ,60, 060306. [ CrossRef ] 11. Kennedy, T. 
 BACKSCATTER EFFECT ! VECTOR FORMULATION ACCOUNTING FOR POLARIZATION   AND ABSORPTION EFFECTS AND SMALL OR LARGE SCATTERERS v  0HYSICAL 2EVIEW "   VOL   PP n    *ULY   0 $ 3PUDIS  # , ,ICHTENBERG  " -ARINELLI  AND 3 .OZETTE  h-INI 
 4(% 
 rad (2.53) The pulse timing jitter must be less than  ∆t= =×= ×− − τ 316 2 12 10 316 24 5 106 9. s  (2.54) The pulse-width jitter must be less than  ∆PW s = =×= ×− − τ 316 12 10 3166 106 9 (2.55) The pulse amplitude change must be less than  ∆A A= = =1 316000316 0 3 . percent (2.56) The A/D sampling time jitter must be less than  J= =×= ×− − τ 316 12 10 3166 106 9s (2.57) Of the above requirements, oscillator phase noise may dominate. 
 C. J.: Minimizing the Effects of Phase Quantization Errors in an Electronically Scanned  Array." Proceedings of Symposium on Electronically Scanned Array Techniques and Applications,"  Ro111e Air De1·elop111ent Center Technical D0rnme111ary Report No. RADC-TDR-64-225, vol. 
 C, and R. M. Goodman: Geodesic Lenses for Radar Antennas, EASCON Rec .. 
 Arenberg, D. L.: .Ultrasonic Solid Delay Lines, J. Acous. 
 850–866, 1991. 137. C. 
 Unlike vacuum tubes, the peak power that  can he achieved with narrow pulse widths is only ahout twice the CW power. 28 This results in  the microwave transistor being operated with relatively long pulse-widths and high duty  cycles. For air-surveillance radar application. 
 RADAR TRANSMITTERS 221 10.Beaver. W..(iCaryotakis. A.Slaprans. 
 35. Schneider, A.: Oversea Radar Propagation Within a Surface Duct, IEEE Truns., vol AP-17,  pp. 254-255, March, 1969. 
 J. Keeler, D. S. 
 MEDIUM AND HIGH 02& IS TO GENERATE A HYBRID FILTER WEIGHT 
 66, no. 1, January 1978, pp. 51–83. 
 2016 ,77, 20–37. 12. Qu, F.F.; Zhang, Q.; Lu, Z.; Zhao, C.Y.; Yang, C.S.; Zhang, J. 
 AP-19, pp. 552-554, July, 1971.  26. 
 The sweep circuits, which comprise thetop row oftheblock diagram, areshown schematically below. Onbeing triggered, the square-wave generator Vzbrightens the cathode-ray tube, switches the sawtooth generator, and, when the sweep isnot delayed, also switches the fixed- marker generator. The sawtooth generator V,,V,(seeSec.13.10) furnishes avery linear positive sawtooth which isofsufficient amplitude todrive one ofthe horizontal deflecting plates ofthe cathode-ray tube. 
 B. D. Steinberg and E. 
 486 INTRODUCTION TO RADAR SYSTEMS  (4) the detection decision was determined hy whether or not the receiver output crossed a  threshold that depended on the desired probability of false alarm. When the noise, or clutter,is  not described by a Rayleigh pdf, the receiver model of Chap. 2 is not optimum and can cause  degraded performance. 
 66. Milne, K.: The Combination of Pulse Compression with Frequency Scanning for Three-Dimensional  Radars. Radio Electronic Engr., vol. 
 E. Holbourn and A. M. 
 For  example, if the state coordinate system is composed of three-dimensional Cartesian coor - dinates centered at the radar, then multiplication by H transforms Cartesian coordinates   (x, y, z ) into polar measurement coordinates (range, azimuth, elevation, doppler) and  Hx ry rz r y x yx x y xz r x yyz r=+− + − +−0 0 0 0 0 0 02 2 2 2 2 2 2 2x x yx y r xr xr ryr yr rzrzr r2 22 2 2 2 2 20 0 0 ++ − − −     x x ry rz r                    (7.28) where r x y z = + +2 2 2is range. The Kalman filter equations for radar tracking are then, simply, generalizations  of the a − b filter equations where a and b vary with time. The Kalman filter update  procedure continues as follows. 
  JDp AND @6(   @(6    7K  SIN P    IS THE  NORMALIZED ROUGHNESS SPECTRUM THE &OURIER TRANSFORM OF THE SURFACE AUTOCORRELATION FUNCTION  )T MAY BE WRITTEN AS  7+     WHERE  + IS THE WAVENUMBER FOR THE SURFACE  )N TERMS OF THE WAVELENGTH ON THE SURFACE  ,    +   O,  &)'52%   B  )N 
  INSTRUMENT  THAT FLEW ON THREE 3KYLAB MISSIONS )TS OBJECTIVES WERE TO VERIFY  PREDICTED WAVEFORM RESPONSE TO WIND AND WAVES  TO MEASURE THE RADAR CROSS SECTION OF THE SEA AT VERTICAL INCIDENCE  TO MEASURE INTER 
 (11.17).  11.4 AMBl~UITY D1AGRAM5•10-12  The ambiguity diagram represents the response of the matched filter to the signal for which it  is matched as well as to doppler-frequency-shifted (mismatched) signals. Although it is seldom  used as a basis for practical radar system design, it provides an indication of the limitations  and utility of particular classes of radar waveforms, and gives the radar designer general  guidelines for the selection of suitable waveforms for various applications. 
 Proctor, and L. D. Schultz, “Predicting long-term opera - tional parameters of high-frequency sky-wave communications systems,” ESSA Tech. 
 21.2. In this figure, R0 represents the range from a radar target to the center of the array, and Leff represents the max- imum synthetic antenna length such that the distance from the target to the ex- tremities of the synthetic aperture does not exceed R0 + X/8. It is evident from this geometry that (*+!)2-¥+*2 (2U1)FIG. 
 IRE, vol. 48. pp. 
 ORDER SCATTERING PROCESSES ARE HEAVILY DEPENDENT ON  'E   K  4HEY ALSO SERVE  AS A SENSITIVE INDICATOR OF BACKSCATTER COEFFICIENT ESTIMATION SINCE  TAKING ACCOUNT OF ONLY THE FIRST 
 The general approach to digital down - conversion derives from analog downconversion and sampling, as illustrated in the  frequency domain in Figure 25.8. The spectra on the first and = lines represent signals  at various points in the system, and the spectra on the ∗ and × lines, respectively, rep - resent spectral-convolution  and point-by-point spectral multiplication  operations that  relate those signals. The first line in the figure depicts schematically a real IF signal with one- and  two-sided bandwidths of 40 MHz and 80 MHz, respectively, and with positive- and  negative-frequency components, respectively centered at 75 MHz and −75 MHz. 
 Gating the altitude return has the disadvantage  that targets at ranges corresponding to the aircraft altitude will also be eliminated from the  receiver. Another method of suppressing the altitude return in the pulse radar is to  eliminate the signal in the frequency domain, rather than in the time domain, by inserting a  rejection filter at the frequency.fo .%The same rejection filter will also siippress the transmlttor-  to-receiver leakage. The clutter energy from the main beam may also be suppressed by a  rejection filter, but since the doppler frequency of this clutter component is tlot fixcd, the  rejection filter must be tunable and servo-controlled to track the main-beam cli~tter as ~t  changes because of scanning or because of changes in aircraft velocity. 
 COMPARISON. £n°È  2!$!2 (!.$"//+  3!2 IMAGES ARE DEGRADED BY A MULTIPLICATIVE SELF 
 The average elevation of the city is about 37 m. About 26% of total area (2205.06 km2) is covered by water [ 43], such as rivers, lakes, ponds and ditches. The city has a subtropical monsoon climate characterized by four distinct seasons, abundant precipitation, and considerable sunshine. 
 CANT AMPLITUDE VARIATION  VERSUS FREQUENCY FOR SMALL TIME 
 Inverting to obtain the  period, it can be seen that the doppler-tolerant waveform is one with a linear period  modulation.  The short-pulse waveform also can tolerate unknown shifts in the doppler frequency  when using a single matched filter. 428 INTRODUCTION TO RADAR SYSTEMS  Phase-coded pulse compression. 
 Theinherent geometry ofthebistaticradarismoresuitedtoafixed(nonscanning) fencelike coverage asinFig.14.12,asisobtained withfixedantennas generating fanbeams.. OTHER RADAR TOPICS 555  The fence coverage of the bistatic radar is seen to be quite different from the hemispherical  coverage of tile motiostatic radar. Similar coverage can also be obtained with the monostatic  radar by operating wit11 fixed, rather tila11 scanning, antennas. 
 Main-beam effects  would be included in the platform-motion improvement factor. The constant K is the  noise normalization factor for the MTI filter ( K = 2 for single delay and 6 for double  delay.) G4(q ) is the two-way power of the antenna in the plane of the ground surface. The DPCA performance described in the preceding subsection can be analyzed on  the basis of radiation patterns or the equivalent aperture distribution function.8 If the  radiation pattern is used, the composite performance may be obtained either by apply - ing the pattern functions over the entire 360 ° pattern or by combining the improvement FIGURE 3.13  Simplified double-delay DPCA mechanizationTransmitter A R R A YHybr id Amplifier Delay Line Delay Line Vx− − Σ(q) + jkVx∆(q)Σ(q) − jkVx∆(q) Σ(q) j∆(q) ch03.indd   13 12/15/07   6:03:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 42. C. T. 
 However, this is not a reliable means of discriminating moving  from fixed targets since some fixed targets can look like point targets, e.g., a water tower. Also,  sorne moving targets such as aircraft flying in formation can look like extended targets.)  Successive A-scope sweeps (pulse-repetition intervals) are shown in Fig. 4.3h to e. 
 TER AT INTERMEDIATE TO HIGH GRAZING ANGLES HAS LITTLE DEPENDENCE ON FREQUENCY  AND THE EFFECTS OF WIND SPEED ARE UNCERTAIN  SEEMING TO DEPEND ON POLARIZATION  WIND DIRECTION  AND GRAZING ANGLE IN OFTEN CONFUSING WAYS 9ET VARIOUS EMPIRICAL DESCRIPTIONS AND STA 
 It is for this reason it is shown in this block diagram,  but was not included in the previous discussion of MTI deb.y-line cancelers.  Following the phase detector the bipolar video signal is sampled at a rate sufficient to  ohtain one or more samples within each· range resolution cell. These voltage samples are  converted to a series of digital words by the analog-to-digital (A/D) converter.23•24 The digital  Pho~~  det~ctor  Coho  From --JF  Phase  deteclor !, or m -phase, channel  Sample A/0 and ... 
 ENT TWO 
 Ifa radar scans through 360° and inter- rogates thebeacon through only 6°~ itwill load the beacon only +as much asifitpointed atitsteadily. The traffic capacity ofthebeacons insuch asystem isincreased bya factor ofabout 60. Actually, itis necessary totake account ofthe statistical fluctuations oftheinter- rogation. 
 SHIFTERS  ONE FOR EACH WAVEGUIDE  CONTROLLED THE TRANSMIT AND RECEIVE BEAM SHAPE AND BORESIGHT IN ELEVATION 4HE ELECTRONIC BEAM 
 liven wit11 an iridcx of refractiori in the vicinity of 0.5 to 0.6, the thickness of the metal-  plate leris becomes large unless inconveniently long focal lengths are used. The thickness may  he recttrced by zo~iirig just as with a dielectric lens. The bandwidth of a zoned metal-plate lens  is larger than tlii~t of an urizoticd lens, but tile steps in the lens coritour scatter tlie incident  energy iri undesired directions, reduce the gain, and increase the sidelobe level. 
 SENTED AT  )%%% 2ADAR #ONFERENCE !VAILABLE FROM $4) )NTERNET SITE WWWDIVTECSCOM   - 'AUDREAU ET AL  h(IGH PERFORMANCE  SOLID 
 BORNE  4HE PLATFORM FREQUENTLY DRIVES MECHANICAL AND ENVIRONMENTAL REQUIREMENTS AND OFTEN EITHER ENABLES OR CONSTRAINS THE REFLECTOR SIZE )N 3ECTION   REFLECTOR ARCHITECTURES ARE DISCUSSED AND COMPARED  AND IN 3ECTION   MECHANICAL AND ENVIRONMENTAL DESIGN CONSIDERATIONS ARE ADDRESSED #HAPTER 3YNOPSIS  4HE BALANCE OF THIS CHAPTER IS DIVIDED INTO FIVE SECTIONS  3ECTION  SUMMARIZES THE BASIC DESIGN PRINCIPLES AND PARAMETERS GOVERNING REFLEC 
 K. Barton and H. R. 
 Ê " 1,/" ÊÊ "ÊÊ, ,Ê, 
 The cathode is thus 3000 volts  below earth, and the grid and inferior anodes are also  probably a thousand or more volts below earth; a shock is experienced if they are touched, but the high-voltage  anode end is safe. Of course, a surface charge tends to accumulate on the inside of the tube itself, owing to the electron beam impinging on the glass wall. If no means were provided for draining away this surface charge the electron beam of the CRT would continuously be ‘going  nowhere very fast,’ and a saturation charge would build up. 
 BALANCED   ) AND 1 CHANNELS IN ORDER TO MAXIMIZE IMAGE REJECTION  AS EXPLAINED BELOW 4HE MIXERS  MUST HAVE $# COUPLED )& OUTPUT PORTS AND BE PRESENTED WITH A GOOD MATCH AT BOTH THE  WANTED LOW FREQUENCY OUTPUT AND THE UNWANTED SUM FREQUENCY ! MATCH AT THE SUM FREQUENCY CAN BE PROVIDED USING A DIPLEXER FILTER 6IDEO FILTERING IS REQUIRED TO REJECT THE SUM FREQUENCY MIXER OUTPUTS AND ALSO PROVIDES REJECTION OF WIDEBAND NOISE FROM THE VIDEO AMPLIFIERS  WHICH WOULD OTHERWISE ALIAS TO BASEBAND THROUGH THE !$ CON 
 Pulse compression has been infrequently used for meteo - rological applications because short pulse peak power has not been a limitation on  weather radar system performance. Keeler and Frush,92 however, described how atmo - spheric distributed targets may be treated as frozen (fixed) “slabs” of scattering centers  such that they approximate layers of nonfluctuating scatterers as the coded radar pulse  propagates through them. Thus, each scattering slab produces a return signal that can  be compressed by the compression filter in the same way as for individual point targets. 
 Dickey, F. R., Jr., and M. M. 
 TABLE 24.1  ECCM Techniques Versus ECM Technique Countered ( Reproduced with permission  from Slocumb and West5 © Artech House 2000 and G. V . Morris28) Radar  Subsystem ECCM TechniqueECM Technique Category Countered NoiseFalse TargetRange Gate Pull OffVelocity Gate Pull Off Angle Antenna  relatedLow or ultra-low sidelobes × × Monopulse angle tracking × Low cross-polarized response × SLB (sidelobe blanking) × × SLC (sidelobe canceler) × Electronic scan × × × Adaptive receive polarization × Cross polarization cancellation × Transmitter  relatedLow cross-polarized antenna × High power × Pulse compression × Frequency diversity × Frequency agility × × PRF jitter × × Receiver  relatedRGPO memory nulling × Bandwidth expansion × × Beat frequency detector × × Cover pulse channel processing × Home-on-jam × Leading/trailing edge track × Narrowband doppler noise detector × × Velocity guard gates × × Signal  processing  relatedVGPO reset × × Signal realism × × × Acceleration limiting × × × Censored or ordered statistic CFAR × × Doppler/range rate comparison × × Time average CFAR × Total energy test × ch24.indd   9 12/19/07   6:00:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 For example, let Tr(sin B), r,-(2 sin 9) denote the reflection coeffi- cients corresponding to scan angles of sin 9 at the radiating aperture and 2 sin 9 at the input aperture. If Fr(sin 9) - 0.2 and ^-(2 sin 9) - 0.5, the magnitude of the radiated lobe directed at 3 sin 9 would be Fr(sin 9) T/2 sin 9) = 0.1, or 20 dB down from the main lobe. Similar results can be expected from series feeds67 and from reactive parallel feeds.48 Mutual Coupling and Surface Waves. 
 This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http: //creativecommons.org /licenses/by/4.0/). 85. sensors Article A Data-Driven Approach to SAR Data-Focusing Cataldo Guaragnella1,* and Tiziana D’Orazio2 1DEI—Department of Electrical and Information Engineering, Politecnico di Bari, 70126 Bari, Italy 2STIIMA—Institute of Intelligent Industrial Technologies and Systems for Advanced Manufacturing, CNR—Italian National Research Council, 70124 Bari, Italy; tizianarita.dorazio@cnr.it *Correspondence: cataldo.guaragnella@poliba.it; Tel.: +39-080-596-3655 Received: 6 February 2019; Accepted: 4 April 2019; Published: 6 April 2019/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: Synthetic Aperture RADAR (SAR) is a radar imaging technique in which the relative motion of the sensor is used to synthesize a very long antenna and obtain high spatial resolution. 
 Code was written in the MATLAB environment (R2016a, MathWorks, Natick, MA, USA) and not optimized for performance. 4. Conclusions It was shown that unsupervised feature learning algorithms can be effectively used in conjunction with optical ﬂow methods to generate 2CMV AGI products. 
 Rept. PTR-6C, June 25, 1943 (ATI 14009). Reprinted in Proc. 
 CODED WAVEFORMS 4ABLE   &)'52%     %XPANDED VIEW OF 0., AMBIGUITY DIAGRAM FOR  
 9.6 or they may be used as receiver protectors. For example>4 a  VHF balanced duplexer configuration using 32 PIN diodes mounted in 33 inch coaxial line (16  in each of two SPST shunt-type limiters) handled 150 kW peak power, 10 kW average power,  with a pulse width of 200 ,us. At the frequency of operation (200 to 225 MHz), the use of  self-actuated diodes was practical. 
 #!%                 $ $"!  "$!  #" !    "   !! #        ! " ! " # !%   #  &)'52%  2ANGE CORRELATION EXAMPLE WITH  02&S. 
 In  addition, the long wavelengths characteristic of HF radar also provide distinctive information  regarding the sea, as well as aurora, meteors, and land features. (Although the HF band is  officially defined as extending from 3 to 30 MHz, for radar usage the lower frequency limit  might lie just above the broadcast band, and the upper limit can extend to 40 MHz or more.)  The ability to see a target at long range by means of ionospheric refraction depends on the  nature of the ionosphere (the density of electron concentration) and the radar frequency, as  well as the normal parameters that enter into the radar range equation. Unlike conventional  microwave radar, the specific frequency to be used by an OTH radar is a function of the range  that is desired and the character of the, ionosphere. 
 The following CFAR met h- ods are possible. Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  117     12.1.5  The CASH -CFAR   L LLLL LLLsamples of the digital signal SUT-TVcomparator target identification. .SUT TVs t r o a g e . 
 25-28, 1977, IEE (London) Publication no. 155, pp. 33-35. 
 V  CORRESPONDING TO A REFERENCE  SIGNAL ROTATING AT  V RADIANS PER SAMPLE  CENTERING THE SIGNAL SPECTRUM  8 V ABOUT  ZERO  4HE UNWANTED IMAGE IS RE 
 ING A PARTICULAR 3.2 OF INTEREST  3. ALONG WITH ITS CORRESPONDING PROBABILITY OF  DETECTION 0D   2EDUCE  3. BY A FACTOR RELATED TO THE RELATIVE OUTPUT hPOWERv OF THE MATCHED  FILTER AS A FUNCTION OF AMBIGUOUS RANGE WITHIN THE )00 3EE THE THIRD ROW OF PLOTS  IN &IGURE    7ITH THE REDUCED 3.2  DETERMINE THE NEW  0D AS A FUNCTION OF AMBIGUOUS RANGE  WITHIN THE )00 FROM THE UNECLIPSED DETECTION CURVE  !VERAGE THESE NEW 0D VALUES ACROSS THE )00 4HE RESULT WILL BE A NEW  DETECTION CURVE INCLUDING THE AVERAGE  EFFECT OF ECLIPSING AND  RANGE GATE STRADDLE &OR A FIXED  0D  THE DIFFERENCE IN 3.2 BETWEEN THE UNECLIPSED AND  THE ECLIPSED DETECTION CURVES IS THE AVERAGE ECLIPSING AND RANGE GATE STRADDLE LOSS 4HIS DIFFERENCE REPRESENTS THE AVERAGE INCREASE IN SIGNAL 
 When optical processing is employed, the  linear FM. or chirp, pulse-compression waveform readily lends itself to the same type of  processing as described for the cross-range signal.' The form of the lines.. FM signal in the  range dimerisiori is similar to the form of tlie signal in the cross-range dimfnsion. 
 19.1. The illumi- nator maintains the target within its radar beam throughout the engagement. The missile receives the target-reflected illumination in its front antenna and a sample of the directly received illumination (often through sidelobes of the illuminator antenna) in its rearward-looking reference (rear) antenna. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 is defined as real space , the hemisphere into which energy is radiated. The infinite  region outside the unit circle is referred to as imaginary space . 
 Thecharge-coupled devicehasalsobeenconsidered forapplication inpulsecompression.19 Eachofthesedelayslineshasdifferent characteristics andpreferred regionsofoperation as regardsbandwidth andpulseduration.16Onlythesurfaceacoustic wave(SAW)devicewillbe described hereasanillustration ofatypicaldispersive delaylinesuitableforradarapplicati0n.10 Thesurface-acoustic-wave delayline,shownschematically inFig.11.16,consists ofa piezoelectric substrate suchasathinsliceofquartzorlithiumniobatewithinputandoutput interdigital transducers (IDT)arranged onthesurface.ThedesignoftheIDTdetermines the impulseresponse oftheSAWdelayline.Efficient electric-to-acoustic coupling occurswhenthe.j -' Thermal compression .. bondedAucontacts Interdlgltol electrode transducers Highlypolished piezo-electric surfaceFigure11.16Schematic ofasimplesurface acoustic wave(SAW)delayline.(From Briscol, 22Courtesy Proc.JEEE.). EX I KAC7'1ON 01: INFORMA? ION AND WAVEFORM DESICiN 425  - ll~lll~lllllll I I I I1 I1 I1 I1 I 1 I 1 I Oulpul 1 *--  Figure 11.17 Three basic forms of  SAW interdigital transducers for  linear FM pulse compression. 
 The RUS-2 used two trucks, one for the transmitter and one for the re- ceiver, separated by about 300 m to provide receiver isolation. Although the RUS-2 used two sites, separation was not sufficient to define the configuration as bistatic. The French also deployed a bistatic CW radar in a two-fence con- . 
 Related devices that obtain phase change by relative rotation of crossed dipoles in a circular  guide or cavity are described by Kummer.''  A different form of mechanical beam steering is used in an array with spiral antenna   element^.^^.^' The linearly polarized beam radiated by a flat, two-dimensional array of spirals  may be scanned by rotating the individual spiral antenna elements. One degree of mechanical  rotation corresponds to a phase change of one electrical degree. No additional phase-shifting  devices are required. 
 If the multiplier  is characterized by an output phase distortion as a function of input frequency given  by f (w), then a predistortion of the input signal by phase −f (w)/M will equalize the  multiplier response. Predistortion can be performed very precisely by adding the phase  modulation via the DDS that is used to generate the chirp waveform. Waveform Upconversion. 
 The shape  of the pulse is not perfectly rectangular; the rise and decay times are not zero, for this would  require an fifinite bandwidth. The effect of noise is to perturb the shape of the pulse and to  shift the time of threshold crossing as shown by the dashed curve. The maximum slope (rate of  rise) of the leading edge of a rectangular pulse of amplitude A at the output of a video filter is  \ 'IRect~n~u/or"~u/se F- p/us noise [ +---- ~hreshold  Figure 11.1 Measurement of  time delay using the leading (or \ \ trailing) edge of the pulse. 
 The computer permits the inherent  flexibility of an array to be exploited by efficiently controlling the radar and scheduling its  operations. However, the cost of achieving this capability is not insignificant and has been one  of the major factors in making the array radar expensive.  The computer is needed in a phased-array radar to provide beam-steering comn~urlds for  the individual phase shifters; signal management by determining the type of waveform, the  number of observations, data rate, power, and frequency; the corresponding signal processitry  and dutu processing in accordance with the mode of operation; outputs of l~rocessrd Juta to  322INTRODUCTION TORADAR SYSTEMS· spurious quantizatioll lobes,similartogratinglobes.Thepeak-quantization loberelativetothe mainbeam,whenthephaseerrorhasatriangular repetitive distribution is . 
 (d, Off-rentering roil. (CJ Toroidll iron- rorc deflwtion rail. (f)-ii,-rnr<> clefl.rt,or, coil with cfistril}utcd win<lirm,. 
 Another  challenge is minimizing power supply phase pulling when PRFs and pulsewidths vary  over more than 100:1 range. MFAR systems not only have a wide variation in PRF  and pulsewidth but also usually exhibit large instant and total bandwidth. Coupled  with the large bandwidth is the requirement for long coherent integration times. 
 Mandatory carriage of a dual axis log (which measures speed in  the forward and transverse directions) is required on ships above 50,000 gt. This is  typically a doppler log. On smaller ships, GNSS is used to provide SOG and is often  the user-preferred ground stabilization source for radar, even for a ship fitted with a  doppler log. 
 ESSARILY LOOK LIKE THE SIGNAL BEING DETECTED  BUT IF A MATCHED FILTER IS USED  THE SHAPE OF THE TARGET SIGNAL MUST ALREADY BE KNOWN 4HE MATCHED FILTER IS OPTIMAL IN THE SENSE &)'52%   '02 3OIL 3UITABILITY -AP OF THE #ONTINENTAL #ONTERMINOUS  5NITED 3TATES  #OURTESY  OF 53$! 
 frequency  characteristic is followed by a hard limiter and by a second dispersive delay line with a  characteristic inverse to the first. (If the limiter were omitted, the circuit would operate simply  as a linear riondispersive time delay.) It has been claimed that there was no discernible loss in  detectability with this CFAR, but that the detectability loss for log-FTC is about 3 dB.  A variation of this technique has been applied to chirp pulse-compression radar to  achieve CFAR in conjunction with pulse compression. 
 THIRD OF THE MICROWAVE SPECTRUM 4HIS SPECTRUM SPACE HAS BEEN REDUCED CONSIDERABLY OVER THE YEARS WITH THE ADVENT OF MANY COMMERCIAL USERS OF THE SPECTRUM IN THE AGE OF hWIRELESSv AND OTHER SERVICES REQUIRING THE ELECTROMAGNETIC SPECTRUM 4HUS  THE RADAR ENGINEER IS INCREASINGLY EXPERIENCING SMALLER AVAILABLE SPECTRUM SPACE AND BANDWIDTH ALLOCATIONS THAT CAN BE VITAL FOR THE SUCCESS OF MANY RADAR APPLICATIONS 3IGNAL 
 As illustrated in Fig. 11.11, the theory is quite accurate at broadside incidence (the specular case), but the agreement between measurement and prediction becomes progressively worse as the scattering angle moves away from that direction. Keller's geometrical theory of diffraction (GTD) offers an improvement in both the polarization dependence and the predicted values in the wide-angle regions.35'36 GTD is a ray-tracing method that assigns an amplitude and phase to fields dif- fracted at smooth shadow boundaries and at surface discontinuities. 
 Forested hills 15 / 15 S band S band 2.71VV HH VH HV Fully polarLow graz.  angleLow graz.  angle20 – 70 20 – 70 28 – 66TABLE 23.3  Summary of Measurement Programs for Bistatic Scattering Coef ficient, σB0 (In-plane data is shown in bold type—see subsequent text.)   (after M. 
 The addition ofthis stabilizing !0 .0 ) FIG.10.24.—Characteristics ofthe4J70series. Magnetic field =2700 gauss Pulse current =70amp Pulse duration =0.8psec PRF =400ppS. cavity has the disadvantage, however, ofreducing the tuning range of the magnetron; further, itmay aggravate mode instabilities. 
 MATCHED TO THE APPROPRIATE LEVEL !N INDUSTRY 
 i f-;--~--j-f-. ,Ir--- -.....,...... .....-'- ---1""1,"f-'---:"--,.--Ii---'h -0.8 ' . 
 NEOUSLY BE INTERPRETED AS FALSE TARGETS #/(/ AND 4IMING )NSTABILITY  4HE MAJORITY OF THIS DISCUSSION HAS FOCUSED  ON THE 34!,/ AS THE MAJOR CONTRIBUTOR TO RECEIVER STABILITY /THER CONTRIBUTORS SUCH AS THE SECOND ,/  THE COHERENT OSCILLATOR #/(/  IF USED   !$ AND $! CONVERTER CLOCKS CAN ALL BECOME SIGNIFICANT !$ AND $! CONVERTER CLOCK JITTER BECOMES INCREASINGLY SIGNIFICANT AS SAMPLE RATES AND )& FREQUENCIES ARE INCREASED 4HE EFFECTS OF !$ AND $! CONVERTER CLOCK PHASE NOISE AND JITTER IS DESCRIBED IN 3ECTIONS  AND  4HE JITTER ON TIMING STROBES USED TO PERFORM TRANSMITRECEIVE 42  SWITCHING IS TYPICALLY LESS STRINGENT THAN THAT OF !$ CLOCKS  AS IT DOES NOT HAVE A DIRECT IMPACT ON THE SIGNAL PHASE (OWEVER  IF COMPONENTS SUCH AS TRANSMITRECEIVE SWITCHES OR POWER AMPLIFIERS HAVE A TRANSIENT PHASE RESPONSE OF SIGNIFICANT DURATION  TIME JITTER ON THE SWITCHING TIME CAN BE TRANSLATED INTO A PHASE MODULATION OF THE TRANSMITTER OR RECEIVER SIGNAL 4OTAL 2ADAR )NSTABILITY  4HE PRIMARY SOURCES OF RADAR INSTABILITY ARE USUALLY THE  RECEIVER 
 , vol. 52, pp. 591–602, 2004. 
 17.20 for various false-alarm probabilities and num- ber of pulses integrated. The generalized results are based on the realization that Marcum's curves46 are very similar over a wide range of parameters; one can reasonably use a single universal Marcum curve as shown in Fig. 17.21. 
 J.: Design of Nonrecursive Digital Moving-Target-Indicator Radar Filters, Electronics 1-ettrr,  vol. 8, pp. 359-360, July 13, 1972. 
 Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft.  MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 A major enabler for AESAs is the state of the art in microwave integrated circuits.1  This has followed the dramatic cost and performance gains available in most semicon - ductor technologies. Each T/R channel has self-diagnosis features, which can detect  failure and communicate that to the beam steering controller for failure compensation. 
 On the other hand, the threshold can only pass accumulations of (extended) . Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  116     targets if the rank r is chosen high enough. The major disadvantage of the OS -CFAR is the  high processing power required for performing the sorting alg orithm. 
 PAL TIDAL CONSTITUENTS ALIAS INTO UNWANTED FREQUENCIES NEAR ZE RO  ONE  OR TWO CYCLES   PER YEAR  )N PARTICULAR  THE DOMINANT TIDAL CONSTITUENT  THE COMMON TWICE 
 19. Davies. D. 
 It is not practical to i~se  a paraboloidal reflector with a single horn feed for aspect ratios greater than about 8 : I,  altho~lgh it is practical to use the parabolic cylinder for aspect ratios of this magnitude or  larger. Another advantage of the parabolic cylinder antenna is that the line feed allows better  control of the aperture illumination than does a single point source feeding a paraboloid. The  patterns in the two orthogonal planes can be controlled separately, which is of importance for  generating shaped beams. 
 Diodephaseshifters.2226.155Theproperty ofasemiconductor diodethatisofinterest in microwave phaseshifters isthatitsimpedance canbevariedwithachangeinbiascontrol voltage. Thisallowsthediodetoactasaswitch.Phaseshiftersbasedondiodedevicescanbe ofrelatively highpowerandlowloss,andcanbeswitched rapidlyfromonephasestateto another. Theyarerelatively insensitive tochanges intemperature, theycanoperatewithlow controlpower,andarecompact insize.Theylendthemselves welltomicrowave integrated circuitconstruction, andarecapable ofbeingusedovertheentirerangeoffrequenl:ies of interesttoradaralthough theirlossesaregenerally lessandtheirpowerhandlingisgenerally higheratthelowerfrequencies. 
 Optical processing.'--3.92 In a synthetic aperture radar the coherent echo signals S, from each  range interval must be stored, without loss of phase, over the time interval required to form the  syritlletic aperture. An amplitude weighting W, is usually applied to each of the signals to taper  the "illumination" of the synthetic aperture so as to achieve lower sidelobes than given by a  uniform illumination. In a focused SAR, a phase weighting exp (j4,) also must be applied to  cornperisate for the spherical wavefront when the scene to be imaged lies within the Fres~iel  regiorl of tlie synthesized aperture. 
 GATE AT A FIXED HEIGHT ABOVE THE GROUND AND WILL TRAVEL PARALLEL TO THE %ARTHS SURFACE 2EFRACTION BETWEEN THE NORMAL AND CRITICAL GRADIENTS IS KNOWN AS SUPERREFRACTION 3UPERREFRACTIVE CONDITIONS ARE LARGELY ASSOCIATED WITH TEMPERATURE AND HUMIDITY  VARIATIONS NEAR THE %ARTHS SURFACE )NVERSIONS ALOFT  DUE TO LARGE 
 C. Peach, “Uncertainties in coherent measurement of the  mean frequency and variance of the doppler spectrum from meteorological echoes,” in 15th Conf.  Radar Meteorol. 
 Iftheecho-signal frequency liesbelowthecarrier, thetargetisreceding; iftheechofrequency isgreaterthanthecarrier,thetargetisapproaching (Fig.3.7). Although thedoppler-frequency spectrum "foldsover"inthevideobecause ofthe actionofthedetector, itispossible todetermine itssignfromatechnique borrowed from single-sideband communications. Ifthetransmitter signalisgivenby (3.4) theechosignalfromamovingtargetwillbe (35) whereEo=amplitude oftransmitter signal kl=aconstant determined fromtheradarequation Wo=angular frequellcy oftransmitter, racl/s Wd=dopperangular frequency shift c/>=aconstant phaseshift,whichdepends uponrangeofinitialdetection Thesignofthedoppler frequency, andtherefore thedirec'tion oftargetmotion, maybefouod bysplitting thereceived signalintotwochannels asshowninFig.3.8.Inchannel Athesignal isprocessed asinthesimpleCWradarofFig.3.2.Thereceived signalandaportionofthe transmitter heterodyne inthedetector (mixer)toyieldadifference signal IIOJ OJ I"0 "0 ::J ::J .~ -Ci. 
 TIONS WHERE LIMITED ELECTRONIC SCANNING IS REQUIRED IS THE SO 
 Hence the  dynamic range of operation required of the receiver AGC might be of the order of 90 dB, or  perhaps more.  It is found1' in practice that the maximum gain variation which can be obtained with a  single IF stage is of the order of 40 dB. Therefore two to three stages of the IF amplifier milst  be gain-controlled to accommodate the total dynamic range. 
 Through pulse-width diversity, high resolution is obtained  (usually at short range) whereas for long-range detection, longer pulses provide  increased sensitivity and tend to equalize the along-beam and cross-beam resolutions.  The shorter wavelength Ku-, Ka-, and W-band radars typically use pulse lengths less  than 1 µs to achieve improved range resolution and PRFs between 3000 and 10,000  Hz because of the short-range cloud measurements that are limited by attenuation   ch19.indd   14 12/20/07   5:38:11 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
  PS L  WHERE  RH   STANDARD DEVIATION OF SURFACE HEIGHT VARIATIONS  AND  K   WAVELENGTH 3INCE THIS PROPORTION IS DOWN TO  WHEN  RH   KO AND TO  WHEN  SLPH       SIGNIFICANT SPECULAR REFLECTION IS SELDOM FOUND FOR THE CENTIMETER  WAVELENGTHS GENERALLY USED FOR RADAR .EVERTHELESS  A SIMPLIFIED MODEL LIKE THIS IS  CONVENIENT FOR SOME PURPOSES /BSERVATION OF REFLECTED SUNLIGHT FROM RIPPLED WATER  FROM ROADS  AND FROM OTHER  SMOOTH SURFACES LEADS TO THE POSTULATION OF A FACET THEORY  4HE ONLY SUNLIGHT REACH 
 DC POWER CONDITIONERS TO HARMONICS OF THE  02& 7HEN AC 
 VEILLANCE RADARS ARE FREQUENTLY SUPPLEMENTED BY TYPICALLY  SMALLER MEDIUM 
 pp 17.5 1x0. 190 192. 1954. 
 583-589, November, 1976.  56. Goggins, W. 
 Anexample oftheAGeportion ofatracking-radar receiver isshowninFig.5.5.A portionofthevideo-amplifier outputispassedthrough alow-pass orsmoothing filterandfed hacktocontrolthegainoftheIFamplifier. Thelargerthevideooutput,thelargerwillbethe From mixer ---~-- f2dl~Range gateand boxcarConicalscanmodulation toangle-error detector '----~---- Delayvoltage ~ Fi~urt, ~.~Blockdiagram oftheAGeportionofatracking-radar receiver.. feedback signal and the greater will be the gain redi~ction. 
 B. Mack: Introduction to Radar Cross-Section Measurements,  Proc. IEEE, vol. 
 23-25, 1973, pp. 160-165.  52. 
 The combatants never sighted  each other visually from start to finish, and the aid given  by spotting aircraft was held over, as radar aid was  sufficient for the action. It is to be anticipated that  continuous-wave systems rather than radar will be of  use in bringing vessels safely to harbour, and that non-  pulse systems, as well as radar with corner-reflecting  buoys, will guide ships safely along sea-lanes. It is  interesting to reflect that the Decca system of con-  tinuous-wave navigation was used to bring small vessels  into French harbours during the War, with an accuracy  of yards. 
 Digital Pulse Compression. Digital pulse compression techniques are routinely used for both the generation and the matched filtering of radar waveforms. The digital generator uses a predefined phase-versus-time profile to control the signal. 
 M  r  
 1 /" Ê/ 
 Ê" "-* 
 Cross, D. C.: Low Jitter High Performance Electronic Range Tracker, IEEE 1975 lmenwtiu,wl Radar  Conference, pp. 408-411, IEEE Publication 75 CHO 938-l AES. 
 antenna. 229  Faraday rotator. 296  Fast Fourier Transform, 123  and multiple beams. 
 Barrick, D. E.: First Order Theory and Analysis of MF/HF/VHF Scatter from the Sea, IEEE Trans., vol. AP-20, pp. 
 Kartaschoff, J. Vanier, J. Vig, G. 
 OFF VOLTAGE OF THE &%4 THAN FOR A POWER AMPLIFIER 4HE PINCH 
 29-38, March, 1956.  57. Dillard, G. 
 A. Weil Equipment Division Raytheon Company 4.1 INTRODUCTION The Transmitter as Part of a Pulsed Radar System. Figure 4.1 shows a block diagram of a typical pulsed radar system. 
 Miller and M. Drinkwine, “High voltage microwave devices: An overview,” presented at  International Conference on Compound Semiconductor Mfg., 2003. 21. 
 Semiconductor devices such as the SCR (silicon-  controlled rectifiers) can also be used in this application.' Therefore, the name active-switch  modulator is sometimes used to reflect the fact that the function of a hard-tube modulator can  RADAR TRANSMITTERS 215 Pulse transformer U?""" Damping networkDespiking cicui!L8 Hydragl!n lhyralronCharging Charging Impedance dtOde ..pulse-formingnetwork JrHlll~._-"--.~"ITf1 LCH Bypass diodeEnergy Trigger Insourse --~ Figure6.14Diagram ofaline-type modulator. asathyratron orignitron iscapableofhandling highpowerandpresents alowimpedance whcnconducting. However, agastubecannotbeturnedofTonceithasbeenturnedonunless theplatecurrentisreducedtoasmallvalue.Theswitchinitiates thestartofthemodulator pulsebydischarging thepulse-forming network, andtheshapeandduration ofthepulseare determined bythepassivecircuitelements ofthepulse-forming network. 
 The basic feature of CFAR is that the false alarm probability remains approximately constant in clutter by a threshold, riding a definite value above clutter. Targets with an echo  power exceeding the threshold level can still be detec ted. The CFAR is completely realized in  digital signal processing. 
 Therefore Gisalways less than 1[Eq. (l)], approaching, forlarge values ofthecathode resistor, thevalue AL/(U +1), where pisthevoltage amplification constant ofthetube. Since l/GO is nearly always considerably less than O,the amplifier has afaithful response. 
 4(% 
 Examples of RCS Characteristics Simple Objects. Because of its pure radial symmetry, the perfectly conducting sphere is the simplest of all three-dimensional scatterers. Despite the simplicity of its geo- metrical surface, however, and the invariance of its echo with orientation, the RCS of the sphere varies considerably with electrical size.FIG. 
 Subrefraction.  If the motions of the atmosphere produce a situation where the  temperature and humidity distribution create an increasing value of N with height,  the wave path would actually bend upward and the energy would travel away from  the Earth. This is termed subrefraction . 
 ABILITY OF A SIGNIFICANT OUTAGE OF DATA IS MUCH REDUCED IF TWO SOURCES ARE AVAILABLE 7ITH A MORE ACCURATE TRACK  TIGHTER ASSOCIATION CRITERIA CAN BE USED FOR DETECTIONS )F THE BIASES CANNOT BE EFFECTIVELY REMOVED  THEN THERE MAY BE  AN ADVANTAGE TO ASSO 
 The radar engineer would call it a false alarm. A type II error is one in which the  signal is erroneously considered to be noise when signal is actually present. This is a missed  detection to the radar engineer. 
 .. ., ,“.. ,.,,. 
 In a low-gain amplifier the input power  which appears at the output can be a sizable fraction of the total. The conversion efficiency of  s CFA is defined as  RF power output - RF drive power Efficiency = d-c power input (6.1  This is a conservative definition since the RF drive power is not lost but appears as part of the  output.  RADAR TRANSMITTERS 211 drive-pulse bymounting anelectrode inthecathode, butinsulated fromit,intheregionofthe drirtspacebetween theRFinputandoutputports.ThisisknownasacutojJ, orcOfltrol, electrode. 
 LIGHTING A STABLE POINT CLUTTER REFLECTOR THAT PRODUCES A SIGNAL RETURN CLOSE TO BUT BELOW  THE DYNAMIC 
 CHIP SIGNAL PROPAGA 
 11.8. One coaxial cable brings r-fpower from thelocal oscillator, which ismounted inawell-shielded compartment inthe receiver box. The other carries thei-fsignal totheAFC discriminator and control circuit inthesame box. 
 2017 ,14, 1765–1769. [ CrossRef ] 16. Kang, M.; Ji, K.; Leng, X.; Lin, Z. 
 The transducers consist ofpiezoelectric quartz, X-cut and optically polished. The two transmission media sofarused aremercury FIG. 16.32.—A supersonic mercury delay line ofvariable length. 
 If the mirror is double-sided, the times between observations correspond to  ith and 8th of a revolution.  Three reflectors can be used instead of four to produce a uniform target observation rate.  [lie rnirror is double-sided. 
 65.Leary,F.:Researching Microwave HealthHazards, Electronics, vol.32,no.7,pp.49-53,Feb.20, 1959.. 66. Mumford, W. 
 r, in knots, and 1 in meters,  1.03~~ (3.2 b)  A plot of this equation is shown in Fig. 3.1.  1.he relative velocity may be written c, = v cos 0, where v is the target speed and 0 is the  angle ~nade by tllc target trajectory and tile line joining radar and target. 
 IRE. vol. 48, pp. 
 \\ X+!Q QQQ Q COS SINSIN COS    ¤ ¦¥³ µ´ 
 gigacycles Figure2.28Theoretical (one-way) attenuation orRFtransmission lines.Waveguide sizesareinchesand aretheinsidedimensions. (Data.fromArmedServices IndexofR.F.Transmission LinesandFittings, ASESA.49-28.). 58 INTRODUCTION TO RADAR SYSTEMS  gas-tube duplexer also introduces loss when in the fired condition (arc loss); approximately  1 dB is typical. 
  8 
 Figure 6shows the imaging results with FFT, Relax, APES and the proposed KA-DBS algorithm. The SNR is set as 10 dB. From Figure 6, it can be seen that the imaging results based on the FFT algorithm is a little blurred, especially for the closely spaced scatters in the red rectangle, while the closely spaced scatters can be well distinguished in the imaging results based on Relax, APES and the 78. 
 CESSED #0) &IGURE  SHOWS THE ADDITIONAL PROCESSING REQUIRED TO GENERATE CENTROIDED 4ARGET 2EPORTS AND THE PROCESSING OF THESE 4ARGET 2EPORTS TO OBTAIN TRACK OUTPUTS FOR DISPLAY TO THE AIR TRAFFIC CONTROL SYSTEM 4HE -4$ RADAR TRANSMITS A GROUP OF  . PULSES AT A CONSTANT PULSE REPETITION FRE 
 SIVELY ASSESSED AND ANALYZED BY ,INCOLN ,ABORATORY  /N TRANSMITTING  THE TOLERANCES ARE LESS SEVERE BECAUSE THE REQUIREMENTS ARE USUALLY  FOR POWER ON TARGET RATHER THAN FOR ACCURATE ANGLE DETERMINATION OR LOW SIDELOBES &IGURE B SHOWS ANOTHER CONFIGURATION THAT HAS THE ADVANTAGE OF SIMPLICITY  %ACH OF THE SWITCHABLE CIRCULATORS CONNECTS EITHER DIRECTLY ACROSS COUNTERCLOCKWISE   OR VIA THE SHORT 
 NOISE LEVEL 4HIS WEIGHTING INCREASES THE FILTER NOISE BANDWIDTH AND HENCE INCREASES THE LOSS IN SIGNAL 
 Thus, if the threshold level were set sufficiently high, the envelope would  not generally exceed. the threshold if noise alone were present, but would exceed it if a strong  signal were present. If the signal were small, however, it would be more difficult to recognize its  presence. 
 The burial grounds extend  from Abu Roash, just to the north of Cairo, southward through Giza, Abusir, Saqqara,  and Dahshur to Meidum approximately 20 km to the south. The famous Step Pyramid of  the 3rd Dynasty ruler, King Zoser, dominates the site of Saqqara. The main monument  is known as the Gisr el-Mudir, which consists of a 400 meter east to west by 600 meter  north to south stone enclosure. 
 0OL  AND * #OLOM  h$ISTRIBUTED #OLLABORATIVE !DAPTIVE 3ENSING $#!3  FOR IMPROVED  DETECTION  UNDERSTANDING AND PREDICTION OF ATMOSPHERIC HAZARDS v PRESENTED AT  TH !-3 !NNUAL  -EETING  3AN $IEGO  !-3    & *UNYENT  6 #HANDRASEKAR  $ "RUNKOW  0 # +ENNEDY  AND $ * -C,AUGHLIN  h6ALIDATION  OF FIRST GENERATION #!3! RADARS WITH #35 
 It is used chiefly for mapping of the ground and imaging of stationary  objects on the ground.  Inverse synthetic aperture radar. In the ordinary synthetic aperture radar the target is station­ ary and the radar is in motion. 
 FACES +ELLER ET AL   MEASURED 8 
 Toovercome this difficulty, provision was made tomodulate the audio signal with a500-cps tone. The modulator was abalanced one, sothat the500-cPs carrier outp-s zero when thesignal was zero. The result- ingvariations inamplitude ofthetone were quite distinctive, even mthe presence ofthe noise modulation, and carried the effectiveness ofthe system down tofrequencies aslow asdesired. 
 FIELD OR EVEN THE REACTIVE FIELD OF THE ANTENNA WHEREAS THE MODEL ASSUMES A FAR 
 The techniques described previously for  reducing leakage in the CW radar apply equally well to the FM-CW radar. Separate antennas  and direct cancellation of the leakage signal are two techniques which give considerable  isolation.  Sinusoidal modulation. 
 TEMPORAL ADAPTIVE PROCESSING FOR NONSTATIONARY HOT 
 Furthermore, themechanisms forfeedingtheelements andsteering thebeamofaconformal array,aswellasthegeneration ofthephase-shifter commands, aregenerally morecomplicated thanthoseofaplanararray.Although itisdesiredthatconformal arraysbeapplicable toany surface, thecomplications thatarisewhendealing withageneralnonplanar surface have restricted itsconsideration torelatively simpleshapes,suchasthecylinder, cone,ogive,and sphere.Eventheseshapespresentdifficulties inanalysis andequipment implementation, and inrealizing antennas competitive withtheplanararray. Thecylinder, whichisprobably thesimplest formofnonplanararray,hasageometry suitable forantennas thatscan3600inazimuth. Thescanning beamofacylindrical anienna doesnotchangeitsshapeandbroaden whensteered, asdoesascanning beamfromaplanar array.Beamsteering inacircularly symmetric arraycanbeaccommodated bycommutating orrotating theaperture distribution. 
 § ©¨¶ ¸· X AEJX A  4HAT IS  THE APERTURE AMPLITUDE DISTRIBUTION REQUIRED FOR TWO SEPARATE BEAMS VARIES  COSINUSOIDALLY  AND THE PHASE DISTRIBUTION IS LINEAR AND HAS THE AVERAGE INCLINATION )N MOST PHASED ARRAY SYSTEMS  ONLY THE PHASE CAN BE CONTROLLED )GNORING THE  REQUIRED AMPLITUDE VARIATIONS STILL  LEADS TO GOOD APPROXIMATIONS FOR FORMING MULTIPLE  BEAMS  BY SUPERIMPOSING THE VARIOUS REQUIRED PHASE 
 Space-based SAR Design Issues.  The options for space-based SAR design30,31  are more limited than for airborne systems, due primarily to the constraints imposed  by viable orbits, including especially sensor velocity, radar range ( R), and system cost.  The following paragraphs review the major themes. 
 He studied the blueprint for some five minutes,  and his quizzical expression clearly showed that he was  on the defensive, thinking, no doubt, that he was being  made the subject of a practical joke.  At length he said, ‘‘I don’t know what it is meant to  be. It couldn’t work, of course. 
 The hard-limiting,  however, causes cross-coupling between the azimuth and the elevation error-signal channels  and can result in significant error." Two-channel monopulse receivers have also been used by  combining the sum and the two difference signals in a manner such that they can be again  resolved into three components after amplification.'.2z  The purpose ill using one- or two-channel monopulse receivers is to ease the problem  associated wit11 rnairitai~ling identical phase and amplitude balance among the three channels  of the conventiotial receiver. These techniques provide some advantage in this regard but they  car1 result it1 uridesired couplilig between the azimuth and elevation chennels and a loss in  signal-to-tloise ratio.  The monopulse antenna must generate a sum pattern with high efficiency (maximum  boresight gain), and a differelice pattern with a large value of slope at the crossover of the offset  beams. 
 This descrip - tion provides insight into the intrinsic impedance variation of the aperture when it is  isolated from other effects, as in the case where each element has an independent feed  (e.g., its own generator and isolator). In this case it, is a simple matter to measure the  voltage-standing-wave ratio (VSWR) in any line and determine exactly the extent of  the impedance and mismatch variation. For many feed systems, this is not possible,  and a measurement of the reflected energy will provide erroneous information and a  FIGURE 13.11  Coupled signals to a central element from neighboring elements ch13.indd   21 12/17/07   2:39:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Probert- Jones14 took this into account, assumed a gaussian shape for the antenna beam, and derived the following equation for the received power: P,G2X2e<|>CT " Pr = ^ 2X <23'12)512(2 In Z)TT2T2 £1 where 2 In 2 is the correction due to the gaussian-shaped beam. By using the relationships in Eqs. (23.7) and (23.8), Eq. 
 Hockfrequenztech. atrder E.T.H.  Rept. 
 Zucker  (eds.). McGraw-Hill Book Co., New York, 1969, p. 231. 
 2016 ,45, 507–513. 31. Zhao, R.; Li, Z.; Feng, G.; Wang, Q.; Hu, J. 
 Timmoneri, and R. Tosini, “Monopulse direction finding in pres - ence of adaptive nulling,” presented at IEE Colloquium on Advances in Adaptive Beamforming,  Romsey, UK, June 13, 1995. 107. 
 294 297.  4J. Rigden. 
 Thus thetotal signal range iscompressed, but there isnocomplete saturation even on very strong signals. Such receivers have not had very extensive tests with conventional airborne radar, but the rather meager results have shown promise. One variant that has not been tried, tothe author’s knowledge, istouse different saturation (orlimit) levels inthe various channels, asinthe three-tone method, making this a“multi-tone” device.. 
 The key elements of this type of radar system are the  impulse generator, the timing control circuits, the sampling detector, and the peak hold  and analogue to digital converter. Frequency Domain Radar.  The main potential advantages of the frequency  domain radar are the wider dynamic range, lower noise figure, and higher mean powers  that can be radiated. 
 AND 
 Most high­ power klystrons for radar application have one or more cavities between the input and output  Electron beam  Cathode -)  Heater~ 0--_  J  Modulating~  onode  E lf'ctron  gun I ......  I  I RF  in space RF  out '  · RF section-·- ···--------I-collector  I  Figure 6.9 Diagrammatic representation or the principal parts of a three-cavity klystron. 202 INTRODUCTION TO RADAR SYSTEMS  cavities to provide additional bunching, and hence, higher gain. 
 Finally, the individual genes of population satisfying the ﬁtness function value condition were selected as the estimated unknown parameters for the coherent point. Substituting the obtained ﬁnal solutions of the unknowns into Equation (5), the low-pass (LP) component of time-series deformation (LP-deformation) could be acquired. Subsequently, in order to obtain the high-pass (HP) deformation component (HP-deformation), the residual phase in Equation (8) was processed with temporal high-pass ﬁltering and spatial low-pass ﬁltering [ 31]. 
 ‘IMPOSSIBLE’ CIRCUITS 89  a square wave. If we consider an ordinary Class A valve  amplifier, with a sine wave applied to its correctly biased  grid, and the whole thing working on the straight part  of the characteristic, then an amplified sine wave is pro-  duced in the anode circuit, a mirror of the grid input.  . 
 SEC. 6.13] HOMING 199 usually made tofacilitate homing inasea-search radar. This usually takes theform ofaprovision for“sector” scan and amodified indicator. 
 The A/D output, including a residual  gain imbalance of ∆, is  V'IQ = V'I + jV'Q (6.32)  V'I = VI − aV3 I − cV5 I (6.33)  V'Q = (1 + ∆)VQ − bV3 Q − dV5 Q (6.34) Substitution of Eqs. 6.33 and 6.34 into Eq. 6.31 yields the amplitudes of the spectral  components listed in Table 6.2. 
 The curve in Figure 16shows that the DEM accuracy does not exceed 0.5 m, which is much smaller than the height di ﬀerence threshold. Thus, we can draw the following conclusion: Even if the SAR images used for interference appears defocused, the obtained DEM can still be used to assist ArcSAR imaging and acquire high precision image. 5.2. 
 Targets not  resolvable in range or angle can be readily resolved in doppler. After targets are resolved in  doppler, measurements in range and angle can be made to a greater accuracy than given by the  nominal resolution in those coordinates.  Application to air traffic control. 
 If both accumulators are clocked at the same rate, the chirp slope is given by  ∆ ∆f tM fS Nfout clk=2 2 (6.52) where  MS = chirp slope word, input to the frequency accumulator  Nf = number of bits of frequency accumulator Frequency modulated and phase modulated waveforms can be created applying time- varying inputs to the frequency modulation (FM) and phase modulation (PM) ports. FIGURE 6.24  Direct Digital Synthesizer block diagramCosine  LookupDACPhase  Truncation+ + fclkfclkPhase  Accumulator + fclkFrequency  Accumulator +MfNf MSNf FM  InputPM  InputfoutPhase  RegisterFrequency  Register ch06.indd   48 12/17/07   2:04:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Wide-area tra ﬃc monitoring with the SAR /GMTI system PAMIR. IEEE T rans. Geosci. 
 To ascertain the angle of elevation with simple ground  equipment which is not highly directional we use two  aerial systems with different polar diagrams, or perhaps  with the same aerial shooting in two different direc-  tions. Thus we can get two rather different conditions  of reception, and by means of a switching motor or some  similar device synchronized with the PRF we can check  these two different conditions alternatively. To get a  quick visual check we arrange that one echo is displayed  along a trace similar to that described for the standard  Type A, and then for the second set of conditions a  different trace is switched on, usually displaced by  having one trace start its travel a little nearer the edge  of the tube than the other. 
 This corresponds to a point on the antenna pattern (the antenna crossover) about 2 dB  down from the peak. It is the optimum crossover for maximizing the accuracy of angle  tracking. The accuracy of range tracking, however, is affected by the loss in signal but not by  the slope at the crossover point. 
 From this results:   € fpmin=1 Tp=v Dsinθ0=2v asinθ0 (10.38)  To avoid ambiguities in range, the maximum PRF is:     € fpmax=c0 2ΔRmax     ∆Rmax is the swath width.  Thus the following is the range for f p:  € c0 2ΔRmax>fp>2v asinθ0 (10.40). Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 87     11 Characteristics of Radar Targets  In this section the characteristics of Radar targets are described for the impingement of ele c- tromagnetic waves. 
 456–460. 52. P. 
 When the   current is removed, the ferrite toroid is said  to be latched  and retains its magnetization  owing to its hysteresis properties. If the  current is in a forward direction, the fer - rite is latched with a particular phase (e.g.,  180°). The ferrite maintains the phase  until a current pulse in the opposite direc - tion is applied. 
 POLARIZED ENERGY CAUSES THE ANTENNA TO DRIVE OFF TARGET IN ONE OF THE QUADRANTS OF THE TWO 
 (The derivation of these limitations and a means of avoiding them by the use of time-varying weights are given in Sec. 15.9.) 75.6 OPTIMUM DESIGN OF CLUTTER FILTERS The statistical theory of detection of signals in gaussian noise provides the re- quired basis for the optimum design of radar clutter filters. Such theoretical re- sults are important to the designer of a practical MTI or MTD system, in that WOODED HILLS10-KNOT WIND WOODED HILLS40-KNOT WIND GROUNDCHAFF SEA RAINI INTERNAL CL SINGLE CANCELLER (dB) . 
 Gray, M., F. Hutchinson, D. Ridgely, F. 
 Also, for active arrays,  it is desirable to keep the high-power transmit amplifiers in saturation. Hence, when  nulling on transmit, it is desirable to use phase-only nulling to maintain the aperture  efficiency. On receive, amplitude weighting across the array is typically used to pro - duce the desired sidelobe levels. 
 Locke23 describes methods for calculating angle tracking lag for a given target  trajectory versus time and set of servosystem characteristics. Range tracking lags  may be similarly calculated, but with typical inertialess electronic tracking systems,  tracking lags are usually negligible. Electronically steerable arrays provide a means for inertialess angle tracking. 
 14. T. Murakami, “Optimum waveform study for coherent pulse doppler,” RCA Final Rept ., prepared  for Office of Naval Research, Contract Nonr 4649(00)(x), AD641391, February 28, 1965. 
 s ( t)  (a)  h( t)  {b) t, ,_  Figure 10.1 (a) Received waveform s(t); (b) impulse response  /r(t) or the matched filter. 372 INTRODUCTION TO RADAR SYSTEMS  We wish to show that the frequency-response function of the linear, time-invariant filter  which maximizes the output peak-signal-to-mean-noise ratio is  H(J) = G0S*(J) exp ( -j2nft 1)  when the input noise is stationary and white (uniform spectral density). The ratio we wish to . 
 Freeman, Y . Shen, and C. L. 
 BASED EMITTER   PROPAGATION CONDITIONS WILL GENERALLY BE SUB 
 ª «­­ ¬­ ­A   4ABLE  GIVES THE INTEGRATION FOR THE EXAMPLE 7HEN THE INTEGRATED POWERS FOR ALL  SEGMENTS HAVE BEEN CALCULATED  THEY ARE SUMMED AND THEN CONVERTED BACK TO D"C 4HE  FINAL ANSWER   
 W. Lee (eds.), Antenna Handbook: Theory, Applications and Design, Techniques  for High Frequency Problems , Chapter 4, New York: Van Nostrand Reinhold Co. Inc., 1988. 
 The plot of the observed quantities as a function of the  load conductance and susceptance, for a fixed magnetic field and anode current, is called a  Rieke diagram, or a load diagram.  An example of the coaxial magnetron performance characteristics is shown in Fig. 6.6a. 
 Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 8.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 The matrix elements represent the multiplying coefficients of a basic phase shift  2p /M, where M is an integer. The phase shift corresponding to the element m,n of the  matrix can be written as  φπ m nMm n m M n M, ( ) ( ) , , , , , , = − − = =21 1 1 1… …  (8.18) An example of a Frank Code matrix for M = 4 is given here:  π π 20 0 0 0 0 1 2 3 0 2 4 60 3 6 9 20 0 0 00 1 2 3 0 2        =0 0 2 0 3 2 10 0 0 0 0 9 0 180 270 0180 0 1        =   8 80 0270 180 90             Concatenating the rows of this matrix yields the phase for each of the 16 subpulses. 
 TO 
 Even optimizing for  sea conditions found in one particular area can create suboptimal solutions in other  areas, and therefore, data from a number of regions need to be used to design a glob - ally effective product. ch22.indd   13 12/20/07   11:10:33 AMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 STATE 4HE 7"'3 MATERIALS ARE ABLE TO PRODUCE VERY HIGH POWER 
 10–16,   May 1960. 38. D. 
 FIELD APPROXIMATION  WHICH  ASSUMES THAT THE DISTANCE FROM THE SCATTERING OBSTACLE TO THE POINT OF OBSERVATION IS LARGE COMPARED WITH ANY DIMENSION OF THE OBSTACLE ITSELF 4HIS ALLOWS US TO REPLACE THE GRADIENT OF 'REENS FUNCTION WITH     YYIKOS      YPO2 O EE 2O 
 Occasionally, the most efficient operating voltage ofthe magnetron orload does not correspond totheoptimum plate voltage forT1,sothat there must besome impedance-matching device between pulser and load. The primary ofapulse transformer may beinserted atAA’and theload connected across the secondary with orwithout the damping element L,R,. Generally speaking, the insertion ofapulse transformer changes somuch thecharacter ofthepulse tailthat itisnecessary toalter radically theso-called “tail damping” circuit. 
 126, pt. 11, paper 3269, 1961.  112. 
 "AND AMPLIFIER CHAIN v 2AYTHEON #OMPANY  7ALTHAM -!  PRESENTED AT .!4/  #ONF -ICROWAVE 4ECHNIQUES  0ARIS  -ARCH     6 , 'RANATSTEIN AND ) !LEXOFF   (IGH 0OWER -ICROWAVE 3OURCES  "OSTON !RTECH (OUSE    ! 3 'ILMOUR  *R   -ICROWAVE 4UBES  .ORWOOD  -! !RTECH (OUSE    #HAP . £ä°Îä  2!$!2 (!.$"//+   + , &ELCH ET AL  h#HARACTERISTICS AND APPLICATIONS OF FAST 
 Computer calculations  have shown that it is unnecessary to vary D in most practical systems. FIGURE 2.44  Use of time-varying weights: ( a) pulse train, ( b) two-delay canceler,  and ( c) three-delay canceler ch02.indd   45 12/20/07   1:44:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Theradarechofromaircraftismodulated bytherotating propellers of pistonengines, andbytherotating compressor andturbinebladesofjetengines.45(The compressor wouldbeseenbyaradarlookingintotheforward partofthejetaircraftandthe turbinewhenlookingintotherear.)Thecharacteristic modulations oftheradarechoesfrom aircraftcan,insomecases,beusedtorecognize onetypeofaircraftfromanother; ormore correctly, onetypeofaircraftenginefromanother. Aircraftjet-engine modulations arelikely tobeofrelatively highfrequency (tentotwentykilohertz perhaps) becauseofthehighspeedof theenginecomponents thatcausethemodulated echo.Thehelicopter withitslargerotating bladesalsoprovides adistinctive modulation oftheradarechothatdistinguishes itfromthe echoesofotqeraircraft.Ashipislesslikelytogivedistinctive modulations, unlessithaslarge rotating radarantennas orrotating machinery withinviewoftheradar. Cross-section fluctuations. 
 BIT 3!2 !ND AGAIN  THE UNIQUE CHARACTERISTICS OF AN ORBITAL 3!2 MADE  THIS AN ACCEPTABLE SOLUTION FOR THE  -AGELLAN DESIGN 4HE KEY REQUIREMENTS FOR THIS  PARADIGM ARE TWO   AN EFFECTIVE SIGNAL ENCODING THAT IS VERY LARGE AND   AN IMAG 
 TION  AND SIGN 
 BAND SYSTEM WAS DEVELOPED BY (OLLANDSE 3IGNAALAPPARATEN OF  THE .ETHERLANDS FOR TACTICAL APPLICATION 4HE LAND 
 348 THEMAGNETRON ANDTHEPULSER [SEC. 10.5 vantage ofthis method isthat sparking may occur within the tuning arrangement athigh pulse powers. An unsymmetrical type oftuning which has advantages for high- power operation isshown inFig. 
 AGeneral-purpose A-scope.—The block diagram ofFig. 13.42 illus- trates anA-scope having provisions for both delayed and undelayed sweeps, fixed range markers, and aninterpolating range marker. The cathode-ray tube used isofthepost-deflection-acceleration type using up to4000 volts over-all with reasonable deflection sensitivity (Sec. 
 C. A. Samson. 
 Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation. 26.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 11. K. 
 IT-14, pp. 734-743.  September, 1968. 
 POLARIZED RADAR MAXIMIZES ITS  MEASUREMENT CAPABILI 
 Second, the Doppler centroid estimation parameter is estimated, and the Doppler centre of the signal is modulated to zero frequency, which is quite useful for the latter sub-image stitching 77. Sensors 2019 ,19, 1920 process. Third, the proper AR predictor factor is set, and the AR parameter can be data-driven based on the Levinson recursion algorithm. 
 Antenna gain constant over its beamwidth Φ and zero elsewhere 3. Range variation across the small illuminated area negligible  PP G d A RP G f vRrt t d= = ∫λ πσ λ σ2 32 0 44 0 02 24 2 ( )Φ∆ (16.21) and so  σλ0 4 022=P PvR G fr t dΦ∆ (16.22) Doppler scatterometers need not use fore-and-aft beams. The Seasat89 and  NSCATT90 spaceborne doppler scatterometers were designed with beams pointed  (squinted) ahead and behind the normal to the ground track. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 4.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 Master Oscillator. 
 TUNED MAGNETRON CAN PROVIDE VERY FAST TUNING RATES &OR EXAM 
 [ CrossRef ] 9. Hu, X.; Oommen, T.; Lu, Z.; Wang, T.; Kim, J.W. Consolidation settlement of Salt Lake County tailingsimpoundment revealed by time-series InSAR observations from multiple radar satellites. 
 2016 ,129, 179–185. 7. MIT Technology Review. 
 This only came about in the mid 1990’s with the availability of MMIC’s ( M onolithic Micro- wave Integrated Circuits), which allowed for higher level of integration.  As a main applic a- tion the automatic distance control appeared in the sense of an intelligent cruise control system (AICC Autonomous Intelligent Cruise Control; ACC Adaptive Cruise Control; ICC Intelligent  Cruise Control).  . 
 ( Courtesy of the Canadian Space Agency ) †  Discussed later in this section. ch18.indd   10 12/19/07   5:13:58 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 An attack on the problem has been suggested by Sikta et al.46 When applying these approximate high-frequency methods of estimating the fields scattered by complex objects, it is necessary to represent the object as a collection of surfaces having relatively simple mathematical descriptions. The ac- tual surface profiles may be approximated by segments that have conveniently simple mathematical descriptions, such as flat plates, truncated spheroids, and truncated conic sections. The total RCS may be formed by summing the field contributions of the individual segments using the methods described above or whatever other tools are available. 
 –75 MHz complex tone 5. Frequency-shifted   signal 6. Real lowpass filter   response 7. 
 ECHO SPECTRA  A MAJOR DIFFICULTY ARISES DUE TO THE MYRIAD FORMS OF CONTAMINATION AND DISTORTION INTRODUCED BY THE IONOSPHERE 4HIS HAS LED TO THE DEVELOPMENT OF NUMEROUS TECHNIQUES FOR ESTIMATING AND REMOVING THE VARIOUS FORMS OF SIGNAL CORRUPTION n !S AN ALTERNATIVE  4RIZNA  AND 0ILON AND (EADRICK HAVE REPORTED A METHOD FOR ESTIMATING  R n FROM SIMPLE MEA 
 57.Mooney, D.H.,andW.A.Skillman: PulseDoppler Radar,chap.19of"RadarHandbook," M.( Skolnik (ed.),McGraw-Hili BookCo.,NewYork,1970. 58.Staudaher, F.M.:Airborne MTI,chap.18of"RadarHandbook," M.LSkolnik (ed.),McGraw-Hill BookCo.,NewYork,1970. 59.Voles,R.:NewApproach toMTIClutterLocking. 
 OFF BETWEEN DYNAMIC RANGE  AND SYSTEM NOISE FLOOR 4OO HIGH A LEVEL  OF NOISE INTO THE !$ CONVERTER WILL DEGRADE THE AVAILABLE DYNAMIC RANGE TOO LOW A LEVEL WILL DEGRADE THE OVERALL SYSTEM NOISE FLOOR 3UFFICIENT TOTAL NOISE SHOULD BE APPLIED TO THE !$ CONVERTER INPUT TO RANDOMIZE OR hWHITENv THE QUANTIZATION NOISE .   2!$!2 2%#%)6%23   È°Î 4HIS CAN BE ACHIEVED WITH RMS INPUT NOISE  R   EQUAL TO THE ,3" STEP SIZE  1  )N  ADDITION  THE INPUT NOISE POWER SPECTRAL DENSITY SHOULD BE SUFFICIENT TO MINIMIZE THE  IMPACT ON SYSTEM NOISE DUE TO THE !$ CONVERTER NOISE 4HE IMPACT ON OVERALL NOISE DUE TO QUANTIZATION NOISE IS GIVEN BY   R RR    1   Rq1    4YPICAL OPERATING POINTS ARE IN THE RANGE OF  R 1     TO R 1     WITH CORRESPONDING  NOISE POWER DEGRADATION DUE TO QUANTIZATION OF  D" AND  D"  RESPECTIVELY )N PRACTICE  THE 3.2 OF HIGH 
 ELEMENT LINEAR ARRAY WITH  K  ELEMENT SPACING WHEN NO INTERFERENCE IS PRESENT  5NIFORM ILLUMINATION AND NO AMPLITUDE AND PHASE ERRORS WERE ASSUMED 4HE DASHED LINE IN &IGURE  SHOWS THE ANTENNA PATTERN FOR THE SAME ARRAY WHEN AN INTERFERING SOURCE IS PRESENT AT   n AND AMPLITUDE AND PHASE WEIGHTING IS USED TO STEER A NULL IN  THE PATTERN IN THE DIRECTION OF THE INTERFERING SOURCE 2ADAR SYSTEMS CAN UTILIZE DETERMINISTIC 2& NULLING TO PLACE NUL LS IN BOTH THE TRANS 
 Mertens, L. E., and R. H. 
 BASED EXAMPLE OF THIS TYPE OF POLARIZATION DIVERSITY )F THE FOUR LINEAR  POLARIZATION POSSIBILITIES ARE EXPLOITED NONCOHER 
 ( 12.9) for determin­ ing the index of refraction. 22  It is possible to automate, by means of a computer, the necessary calculations for deter­ mining the refractive effects of the atmosphere on the coverage or the radar. Such computa­ tions could be made at the radar site to provide the operator with the information needed to  know how a radar is affected by the natural environment. 
 RANGE LENGTH "ECAUSE THE EXCITATION OF THE ELEMENTS OF THE SCATTERING ARRAY IS RANDOM  THE SCATTERING PATTERN IN SPACE IS ALSO RANDOM 4HIS FADING PHENOMENON IS USUALLY DESCRIBED IN TERMS OF THE DOPPLER SHIFT OF THE  SIGNAL 3INCE DIFFERENT PARTS OF THE TARGET ARE AT SLIGHTLY DIFFERENT ANGLES  THE SIGNALS FROM THEM EXPERIENCE SLIGHTLY DIFFERENT DOPPLER SHIFTS 4HE DOPPLER SHIFT  OF COURSE   IS SIMPLY THE RATE OF CHANGE OF PHASE DUE TO MOTION 4HUS  THE TOTAL RATE OF CHANGE OF  PHASE FOR A GIVEN TARGET IS   WWWFW 
 Only thetransmitter rotor isexcited from theline. Ifthetwo rotors areoriented atright angles toone another, novoltage isinduced onthe receiver rotor. .&ny departure from this orientation results inanerror signal ~vhose internal phase isopposite forerrors of opposite sign. 
 Iftwo angles are inerror, there are four beams; ifallthree angles are wrong, sixbeams result. The theory ofthe effect oferrors’ yields the result that aloss inreturned signal of3dbiscaused byadisplacement oftheouter edge ofthecorner ofabout A/2. This limitation requires extremely close attention tothe mechanical construction ofcorner reflectors ofhigh gain. 
 FREQUENCY 
 Plan resolution improves as attenuation increases, provided that there is sufficient sig - nal to discriminate under the prevailing clutter conditions. In low attenuation media,  the resolution obtained by the horizontal scanning technique is degraded, but only  under these conditions do synthetic aperture techniques increase the plan resolution.  Essentially the ground attenuation has the effect of placing a “window” across the  SAR aperture, and the higher the attenuation the more severe the window. 
 Rept. ERL 110-775 78, U.S. Department of Commerce, 1969. 
 £È°Ó{  2!$!2 (!.$"//+  WHERE THIS TECHNIQUE IS APPLIED TO THE RADAR EQUATION AND THE FOLLOWING ARE ASSUMED  R  CONSTANT IN THE ILLUMINATED AREA  !NTENNA GAIN CONSTANT OVER ITS BEAMWIDTH & AND ZERO ELSEWHERE  2ANGE VARIATION ACROSS THE SMALL ILLUMINATED AREA NEGLIGIBLE   00'D! 20' F V2RTT D  ¯L PS LS     &$   AND SO   SL   0 0V2 'FR T D&$    $OPPLER  SCATTEROMETERS NEED NOT USE FORE 
 Aerodynamic drag produced bytheantenna housing must beaslowas possible. This requirement puts agreat premium onassmall anantenna aspossible. Taken inconjunction with the requirement foranarrow beam, this means that the wavelength onwhich the radar operates should beasshort asispracticable. 
 Synthetic Aperture Radar   ....................................... 21.1  21.1 Basic Principles and Early Histor y  ..........................  21.1  21.2 Factors Affecting Resolution of a Radar  System  .................................................................... 
 17. Chu. T. 
 The frequency of a klystron is determined by the resonant cavities. When all the  cavities are tuned to the same frequency, the gain of the tube is high, but the bandwidth is  narrow, perhaps a fraction of one percent. This is known as synchronous tuning. 
 C.: The Long Quest, IRE Trans., vol. ANE-1, no. 2, p. 
  TO INCORPORATE 3CAN3!2 o 4HUS  THE RESOLUTION OPTIONS FOR 2!$!23!4 
 A stretch processor6 can expand or contract the time scale of the compressed- pulse waveform within any defined time window. This general technique can be applied to any waveform, but it is much easier to use with a linear-FM waveform. For any waveform other than linear FM, an all-range pulse expansion approach is required in the received waveform path ahead of the mixer of Fig. 
 VHF (30 to 300 MHz). Most of the early radars developed in the 1930s were in this frequency band. Radar technology at these frequencies represented a daring venture that pushed to the edge of technology known in the thirties. 
 This process can be [Supersomc ISubtractmn delayline Icarried out continuously by thecircuit arrangement ofFig. 16.8, inwhich the signals aresplit into two chan- nels, oneofwhich contains asuper- lfi’1Race&er PPIsonic delay line, and then brought together again forcancellation. F1~. 
 In Figure 9is shown the receiving antenna module block diagram: immediately after every antenna a Low Noise Ampliﬁer stage allow to keep low the noise ﬁgure of the system; the received RF signal pass through two SPDT switches followed by another SPDT switch, this matrix allow to switch the signal between the four antenna feed lines.   Figure 8. Receiving antenna module. 
 In industry this has been applied to the measurement of turbine-blade vibration, the  peripheral speed of grinding wheels, and the monitoring of vibrations in the cables of suspen­ sion bridges. - Most of the above applications can be satisfied with a simple, solid-state CW source with  powers in the tens of milliwatts. High-power CW radars for the detection of aircraft and other  targets have been developed and have been used in such systems as the Hawk missile systems  (Fig. 
 KNOWN  -ARSHALL 
 Acta Geod. Cartogr. Sin. 
 W. H. Stiles and F. 
 J., vol. 27, pp. 58 .HZ, January, 1948. 
 POLARIZED JAMMING 4HIS IS THOUGHT OF AS AN %##- TECHNIQUE  BUT IT IS REALLY NO MORE THAN GOOD ANTENNA DESIGN 4HE CROSS 
 Brookner, “Trends in radar systems and technology to the year 2000 and beyond,” in Aspects  of Modern Radar , E. Brookner (ed.), Artech House, Inc., Norwood, MA, 1988. 37. 
 (The single snake line in this case is rrluch  loriger electrically than the snake lines feeding a linear array.) The single snake line passes  through several modes in traversing the frequency band. It has been said that a 90 by 20"  sector [night be possible using a 30 percent frequency band.67 One of the disadvantages of this  form of two-dimensional frequency-scan array is that it requires a wide band and is very  limited in signal bandwidth, triuch more so than the array which steers in one dimension only.  Another method for eniploying frequency scan in a planar array is to use the frequency  change to steer in one coordinate and phase shifters to steer in the other.68 This is sometimes  called a phnse-/reqrte~tc.\. 
 2.23 determine the correction factor for either cases 1 and 2 or cases 3 and 4 to be  applied to tile signal-to-noise ratio found fronl step 1 above. The resultant signal-to-noise  ratio (SIN), is that which would apply if detection were based upon a single pulse.  3. 
 New York, 1968.  18. Rowman. 
 THE 
 Snowden, “Recent development in compound semiconductor microwave power transistor  technology,” IEE Proc-Circuits Devices Syst ., vol. 151, no. 3, pp. 
 15.15 means that at X band, for example, the maximum departure of  the sea surface from a flat plane must be much smaller than 3 mm. Other Calculational Strategies.  Instead of expanding the exponential in the inte - grand of Eq. 
 3 2ANGE  AND PRECISION VELOCITY UPDATE 065  MAY BE USED FOR WEAPON SUPPORT TO IMPROVE DELIVERY ACCURACY AS WELL AS NAVIGATION   4ERRAIN FOLLOWING AND TERRAIN AVOIDANCE 4&4!  IS USED FOR NAVIGATION AT VERY  LOW ALTITUDES OR IN MOUNTAINOUS TERRAIN 3EA SURFACE SEARCH 333   SEA SURFACE TRACK  334   AND INVERSE SYNTHETIC APERTURE RADAR )3!2   WHICH WILL BE DESCRIBED LATER IN  THE CHAPTER  ARE USED PRIMARILY FOR THE ACQUISITION AND RECOGNITION OF SHIP TARGETS 'ROUND MOVING TARGET INDICATION '-4)  AND GROUND MOVING TARGET TRACKING '-44  ARE USED PRIMARILY FOR THE ACQUISITION AND RECOGNITION OF SURFACE VEHICLE TARGETS BUT ALSO FOR RECOGNIZING LARGE MOVEMENTS OF SOLDIERS AND MATERIALS IN A BATTLE 
 R. Thompson, and J. Sadowski, “Direct numerical simulation  of electromagnetic rough surface and sea scattering by an improved banded matrix iterative  method, “ Johns Hopkins APL Tech. 
 l)  (4.2)  The reference signal and the target echo signal are heterodyned in the mixer stage of the  receiver. Only the low-frequency (difference-frequency) component from the mixer is of intt!r­ est and is a voltage given by  cw  oscillator .~ Reference signal  ~14-..----1 Receiver  (a)  Pulse  modulator  14-_ __, Receiver  (bl Indicator  cw  oscillator  fi  Indicator (4.3)  Figure 4.1 (a) Simple CW radar; (b)  pulse radar using doppler informa­ tion. MTl AND PULSE DOPPLER RADAR 103  Nole that Fqs. 
 However, if a threshold crossing is observed  from any range cell, a second pulse or set of pulses is transmitted with higher energy, and with  a different threshold. A target is declared to be present only if threshold crossings are observed  from the same range cell on both transmissions. The second transmission might also be of  greater resolution as well as higher power. 
 pp. 1960 1964. Apr. 
 pattern is approximately unity. Relative to the beam maximum, therefore, the sidelobes near broadside are increased by approximately 3 dB. 7.3 PLANARARRAYSANDBEAMSTEERING Planar Arrays. 
 W.G..L.G.Dennett. andL.S.Don:3-DRadarBasedonPhase-in-Space Principle. IEEEtTram., vol.AES-2,pp.323-331, May.1966. 
 Sufficient range-resolution permits the separation of the desired target  echo from echoes that arrive via scattering from longer paths, or multipath .  • 'i-f i11im11m ra11ge. A short pulse allows the radar to operate with a short minimum range. 
 ERROR 
 HF Over-the-Horizon Radar   .................................... 24.1  24.1 Introducti on  .............................................................  24.1  24.2 Radar Equat ion  ....................................................... 
 Ê  
 2001 , Atlanta  (Georgia), May 1–3, 2001 pp. 157–162. 89. 
 The distance between the radar and the target is R0(t). The back-scattering property of the target is represented by ξ(z)and zis the vector that locates a generic scatter point on the reference coordinate system. The received signal from the moving target can then be written as follows [ 30,31]: SR(f,t)= rect(t Tobs)rect(f−f0 B)e−j4πf cR0(t)/integraldisplay Vξ(z)e−j4πf c(zT•iR0(t))dz (1) where f0is the carrier frequency, Bthe signal bandwidth and Tobsthe observation time. 
      PRPS R  ;=ª « ¬¹ º »    WHERE Q  IS THE CORRELATION COEFFICIENT AND  .3 IS THE NOISE 
 RANGE !IR 4RAFFIC #ONTROL !IR 2OUTE 3URVEILLANCE 2ADARS USED A MAGNETRON  BUT THE KLYSTRON SEEMS TO BE THE PREFERRED CHOICE FOR THIS APPLICATION #ROSSED 
  
 74. APL, Special sections, “Geosat science and altimeter technology,” Johns Hopkins APL Technical  Digest , vol. 10, 1989. 
 viii CONTENTS  1 1.5 Pulse Compression  11.6 Classification of Targets with Radar  References  Propagation of Radar Waves  Introduction  Propagation over a Plane Earth  The Round Earth  Refraction  Anomalous Propagation  Diffraction  Attenuation by Atmospheric Gases  Environmental Noise  Microwave-Radiation Hazards  References  Radar Clutter  Introduction to Radar Clutter  Surface-Clutter Radar Equations  Sea Clutter  Detection of Targets in Sea Clutter  Land Clutter  Detection of Targets in Land Clutter  Effects of Weather on Radar  Detection of Targets in Precipitation  Angel Echoes  References  Other Radar Topics  Synthetic Aperture Radar  HF Over-the-Horizon Radar  Air-Surveillance Radar  Height-Finder and 3D Radars  Electronic Counter-Countermeasures  Bistatic Radar  Millimeter Waves and Beyond  References  Index  viiiCONTENTS 11.5PulseCompression 420 11.6Classification ofTargets withRadar 434 References 438 12Propagation ofRadarWaves 441 12.1Introduction 441 \2.2Propagation overaPlaneEarth 442 12.3TheRoundEarth 446 12.4Refraction 447 12.5Anomalous Propagation 450 12.6Diffraction 456 12.7Attenuation byAtmospheric Gases 459 12.8Environmental Noise 461 12.9Microwave-Radiation Hazards 465 References 466 13RadarClutter 470 13.1Introduction toRadarClutter 470 13.2Surface-,Clutter RadarEquations 471 13.3SeaClutter 474 13.4Detection ofTargetsinSeaClutter 482 13.5LandClutter 489 13.6Detection ofTargets inLandClutter 497 13.7EffectsofWeather onRadar 498 13.8Detection ofTargetsinPrecipitation 504 13.9AngelEchoes 508 References, 512 14OtherRadarTopics 517 14.1Synthetic Aperture Radar 517 14.2HFOver-the-Horizon Radar 529 14.3Air-Surveillance Radar 536 14.4Height-Finder and3DRadars 541 14.5Electronic Counter-Countermeasures 547 14.6BistaticRadar 553 14.7Millimeter WavesandBeyond 560 References 566 Index 571. PREFACE  Although tlie fundamentals of radar have changed little since the publication of the first  edition, there has been continual development of new radar capabilities and continual im-  provements to the technology and practice of radar. This growth has necessitated extensive  revisions arid tlie introduction of topics not found in the original. 
 ANCE OF STORMS 4HE PRINCIPAL CHALLENGE IS COMPENSATING FOR BACKSCATTER FROM THE LEADING EDGE OF A STORM AND ADJUSTING FOR ATTENUATION TO SEE FAR ENOUGH INTO A STORM TO EVALUATE ITS SEVERITY 4HE BACKSCATTER FROM EACH CELL IS MEASURED  THE POWER REMAINING IS CALCULATED  THE ATTENUATION IN THE  NEXT CELL IS ESTIMATED  AND THEN THE BACKSCATTER IN  THE NEXT CELL IS MEASURED  AND SO ON 7HEN THE POWER IN THE CELLS DROPS TO THE NOISE LEVEL  THOSE CELLS BEHIND IT ARE DECLARED BLIND 3INCE PENETRAT ION RANGE INTO A STORM IS  NOT GREAT  THE -&!2 WEATHER MODE USUALLY HAS PROVISIONS TO MARK THE LAST VISIBLE OR RELIABLE RANGE ON THE WEATHER DISPLAY 4HIS IS SO THE PILOT DOES NOT FLY INTO A DARK AREA BELIEVING THERE IS NO WEATHER !IR $ATA ,INKS  4HE -&!2 IS PART OF A NETWORK OF SENSORS AND INFORMA 
 44. D. A. 
 860–864, 1980. 51. G. 
 DOMAIN FORMALISM DESCRIBED ABOVE /THER WAYS OF VIEWING SEA CLUTTER IN TERMS OF SURFACE GEOMETRY CHARACTERIZE THE SEA  AND THE CLUTTER AS FRACTAL PROCESSES   OR SEEK PARAMETERS DESCRIBING ITS COMPLEXITY BY  DEFINING A hSTRANGE ATTRACTORv 5NFORTUNATELY  THESE STUDIES DO NOT SEEM TO CONTAIN  ANY USEFUL INSIGHTS INTO THE PHYSICAL SCATTERING PROCESSES AT THE SURFACE  EXCEPT  PER 
 Theproblem withamultifunction arrayistoutilize effectively theresource oftimeandtheresource ofradarenergy.Thecomputer allowstheradar toutilizeitsresources effectively byscheduling theexecution ofthevarious functions soas toperform themoreimportant tasksfirst. Amultifunction arrayradarmightbecalledupontoperform thefollowing tasks: Searchofaspecified volumeofspaceataspecified rate,andthedetection oftargets. Trackillitiatioll, ortransition totrack.afteranewdetection isestablished. 
 L. Stephens, D. G. 
 Thecomposite three­ dimensional ambiguity surfaceisshowninFig.11.9c.. Figure 11.9 Threedimensional plot of the ambiguity diagram for a single rectangular pulse. (a) Contours  for constant dopppler frequency (velocity); (6) contours for constant time delay (range); (c) composite  surface. 
 126 INTRODUCTION TO RADAR SYSTEMS  4.6 OTHER MTI DELAY LINES  There are delay lines other than digital devices that have been used in MTI signal processors.  Originally, MTI radar used acoustic delay lines in which electromagnetic signals were con­ verted into acoustic waves; the acoustic signals were delayed, and then converted back into  electromagnetic signals. The process was lossy (50 to 70 dB might be typical), of limited  dynamic range, and spurious responses were generated that could be confused for legitimate  echoes. 
 Linde et al. (private communication), “Warloc: A high-power coherent 94 GHz radar.” 36. J. 
 2.Kraus.J.D.:"Antennas." McGraw-Hili BookCompany, NewYork,1950. .lCutler.C.C.A.P.King,andW.E.Kock:Microwave Antenna Measurements, Proc.IRE.vol.35. pp.14621471.Decemher,1947. 
 10.25,—V-I plotofamagnetron illus- trating theproblem ofmode skipping. V,=magnetron starting voltage V.=critical voltage above which oscilla- tions willnotstart VO=pulser voltage with noload.trons, rarely inpulsed tubes. The second type, called “mode-skip- ping,” iscommon tonearly allhigh- power pulsed magnetrons and thus isofimportance here. 
 AES-8, pp. 648–652, September 1972. 30. 
 Iftheantenna main-beam patternisapproximated bythegaussian shape,thespectrum willalsobegaussian. Therefore, theresultspreviously derivedforagaussian clutterspectrum canbereadilyapplied. Equations 4.25and4.26derivedfortheclutterfluctuation improvement factorapplyforthe antenna scanning fluctuations byproperinterpretation of(J"thestandard deviation, orthe rmsspreadofthefrequency spectrum aboutthemean. 
 Itwill return tothe grids after atime proportional toitsinitial velocity and inversely proportional tothe retarding field. Anelectron that leaves thegrids earlier than the reference electron will have been accelerated bythe r-fvoltage across thecavity and, because ofitshigher velocity, will spend agreater time in thereflection space. Byproperadjustment oftheretarding field, thedelay may bemade tocompensate forits earlier departure, and itmay be made toarrive back atthe grids at the same time asthe reference electron. 
 The dynamic-range requirement of a pulse doppler radar, as determined by main-beam clutter, is a function not only of the basic radar parameters such as power, antenna gain, etc., but of radar altitude above the terrain and the radar cross section (RCS) of low-flying targets. As an example, Fig. 17.18 shows the maximum clutter-to-noise ratio (C/7Vmax) which appears in the ambiguous-range interval, i.e., after range folding, for a medium-PRF radar as a function of radar altitude and the range of the main-beam center. 
 (/2):/. 2!$!2   Óä°{ %ACH OF THESE APPROACHES HAS ITS ADVANTAGES AND DRAWBACKS IN THE CONTEXT OF CON 
 Zoughi, F. T. Ulaby, and A. 
 (This may be an incorrect usage  of the precise definition of decibels as a power ratio, but it is the jargon used by the radar  meteorologist.)  ".I: "k101 ,,IIIITI I"IIRADAR CLUTIER 501 C ::J :u10-2 a. co ~10'3 if> V1,n o b10-4__ L ClJ ~ ~o ~10-5 -""uorn 10-7L-------.J~"'______J--'--.L.L..l..J....L __"_______'____'__'__'__.LJ...L_'___L__..L.__L.,.L.--'-'--'LU 0.1 1 10 r,rainfallrote,mm/hrFigure13.12Exact(solidcurves)and approximate (dashed curves) back­ scattering crosssectionperunitvolume ofrainatatemperature of18°C.Exact computations obtained fromF.T. Haddock, approximate curvesbased ontheRayleigh approximation. 
 ,  {N -I), and </J, is any constant phase applied to all elements. The normalized radiation  pattern of the array when the phase difference between adjacent elements is </J is given by  G(8) sin2 [Nn(d/).)(sin f}  N2 sin2 [n(d/..l)(sin 0 sin 00)]  sin 00)]  The maximum of the radiation pattern occurs when sin O sin 00. (8. 
 It is plotted in Fig. 2.2d.  The standard deviation of the Rayleigh density of Eq. 
 IRE,vol.38,pp.l422~l428,December, 1950. 19.Horton, B.M.:Noise-modulated Distance Measuring Systems, Proc.IRE,vol.47,pp.821-828, May, 1959. 20.Rudnick, P.:TheDetection ofWeakSignals byCorrelation Methods, J.Appl.Phys.,vol.24, pp.128-131, February, 1953. 
 ,Ê  //" - $ESCRIPTIONS OF A 3URFACE  -ANY THEORETICAL MODELS FOR RADAR RETURN FROM THE  GROUND ASSUME A ROUGH BOUNDARY SURFACE BETWEEN AIR AND AN INFINITE HOMOGENEOUS  HALF SPACE 3OME INCLUDE EITHER VERTICAL OR HORIZONTAL HOMOGENEITIES IN THE GROUND PROPERTIES AND IN VEGETATIVE OR SNOW COVERS 3URFACE DESCRIPTIONS SUITABLE FOR USE IN MATHEMATICAL MODELS ARE NECESSARILY GREATLY  IDEALIZED &EW NATURAL GROUNDS ARE TRULY HOMOGENEOUS IN COMPOSITION OVER VERY WIDE AREAS $ESCRIPTIONS OF THEIR DETAILED SHAPE MUST BE SIMPLIFIED IF THEY ARE TO BE HANDLED ANALYTICALLY  ALTHOUGH COMPUTERS PERMIT THE USE OF TRUE DESCRIPTIONS 6ERY FEW SUR 
 Again, it is important to characterize devices  over the range of expected operating conditions. The impact of A/D converter spurious signals on radar performance depends on the  type of waveforms being processed and the digital signal processing being performed.  In applications using chirp waveforms with large time-bandwidth products, spurious  signals are less critical as they are effectively rejected in the pulse compression pro - cess because their coding does not match that of the wanted signal. 
 Vidal-Madjar, “C-band radar cross-section of the Guyana Rain Forest: possible use  as a reference target for spaceborne radars,” Remote Sensing of Envir . , vol. 27, pp. 
 ,,", 4HERE ARE MANY SOURCES OF ERROR IN RADAR 
 Theattenuation produced byiceparticles intheatmosphere.:, whether occurring ashail, snow.oricc-crystal clouds. ismuchlessthanthatcausedbyraipofanequivalent rateof precipitatioll.7RGunnandEast ~Istatethattheattenuation inc;nowis . ,0.00349,.1 (,0.00224,. 
 21. pp. 369-373, 1966. 
 CESS OF RECIPROCAL MIXING !NALOG 
 (d) Azimuth should be indicated in all directions represented to not more than plus or minus 3 degrees error and within 10 degrees of the dead ahead position to within plus or minus 1 degree error and desirably within plus or minus 1 degreedeteriorating to a maximum of 3 degrees at 25 degrees from dead ahead position with no sensible time lag in the electrical equipment in order to be used with low altitude blind bombing or blind torpedo attack. (e) It must give immediate identi ﬁcation to the crew as to whether the target is friend or doubtful. Some method of identi ﬁcation of friendly targets is of paramount importance. 
  
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter.  SEA CLUTTER  15.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 Scattering by Surface Features. 
 ICAL REFLECTOR SYSTEMS (OWEVER   OF AZIMUTH STEERING CAN BE ACCOMPLISHED VIA A POLARIZATION DESIGN SCHEME SIMILAR TO THE POLARIZATION TWIST SUBREFLECTOR DESCRIBED &)'52%   #ONFOCAL DUAL REFLECTOR ANTENNA FMAIN  FSUBFSUB0ARABOLIC  -AIN 2EFLECTOR  #OMMON  &OCUS$MAIN 0ARABOLIC  3UBREFLECTOR$SUBFMAIN  A!%3!A2EF    A!%3! -AG 0HASED  !RRAY &EED -AG    . 
 The use of  multiple depressed collectors at intermediate voltages, rather than a single collector,  allows catching each spent electron at a voltage near optimum. Up to ten collector sec - tions have been used in some communication tubes, but three sections are more typical  for high-power TWTs for radar systems. The several different voltages needed for  the depressed collectors add complexity to the high-power voltage supply, but these  voltages need not be as well regulated as the main-beam voltage. 
 MOVING ENDOCLUTTER TARGETS 3HORT 
 Three amplifier levels relative to the squelch yield suitable gains for the detection of short-, medium-, or maximum-range automobiles. The output signal from the doppler amplifier is clipped, differentiated, and integrated. Each pulse from the differentiator makes a fixed contribution to the integrated signal, and the higher the frequency the greater the output. 
 FERENT RESULT FOR EACH DIFFERENT TARGET DOPPLER SHIFT  SO THAT A LARGE NUMBER OF PARALLEL FILTERS WOULD BE NEEDED TO APPROXIMATE THE OPTIMUM PERFORMANCE EVEN WHEN THE CLUTTER CHARACTERISTICS ARE KNOWN EXACTLY !S AN EXAMPLE  THE RESPONSE OF THE OPTIMUM FILTER DESIGNED FOR ONE PARTICULAR TARGET DOPPLER FREQUENCY LABELED AS POINT  ! IN &IGURE   IS SHOWN IN A BROKEN LINE !T APPROXIMATELY  o FROM THE DESIGN DOPPLER  THE PERFOR 
 It would lie about 2 dB higher than the  noise figure shown for the image-recovery mixer. ->  There are other factors beside the noise figure which can influence the selection of a  receiver front-end. Cost, burnout, and dynamic range must also be considered. 
 RECTTPT P A 
   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°Èx 4HESE LONG 
 Air Force to determine the feasibility of using X-band T/R modules  in a solid-state phased array radar.29 As a result of continuous development, phased  arrays are used in multiple military and communications systems. The advantages  of a phased array transmitter include (1) the ability to have multiple independently  steered beams from a single aperture, (2) the speed of electronic versus mechani - cal beam locations, and (3) the efficiency of utilizing space combining instead of  performing the power combining before the antenna. Block diagrams of represen - tative T/R module functions are shown in Figure 11.17. 
 32,  pp. 986–994, 1994. 79. 
 Range and Height Indices; Synchronization. +ince the providing ofelectronic range indices isfrequently intimately associated with synchronization, these topics can best bediscussed together. The discussion will besimplified ifmovable indices aredescribed first. 
 MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 other radar sensors (wingman or support aircraft) on similar platforms to reports by  observers with binoculars. Because the modern fighter is net-centric, using everything  available on- and off-board the aircraft, net-centric operation requires dramatically  higher levels of data exchange and fusion of data for presentation to the operator.  Radar modes can be scheduled between multiple aircraft in real time through the   data links. 
 15.12 ofmicrowave radar suggested that ifsuch facilities could beincorporated inaircraft whose primary mission had little todowith radar—transpo~t aircraft, for exampl~they could serve an important navigational purpose. Since radar inthis application isavery great convenience rather than an imperative operational necessity, itmust make the minimum demands ontheaircraft interms ofweight, drag, power con- sumption, and attention required from airand ground crew. Existing microwave radar scarcely met these requirements in1943. 
 Thus radar coverage  cannot be extended much beyond the line of sight hy this mechanism.  Figure 12.7 is a plot of the electric field strength (relative lo free space) at the target as a  function of the distance from the transmitting antenna. Both the radar antenna and the target  arc assumed to be at a fixed height (100 min this example). 
 522 THERECEIVING SYSTEM—INDICATORS [SEC. 13.12 thesame amount. Since nopulse isinvolved inthereverse regeneration, theexact phase atwhich itappears isimmaterial. 
 Thephasedetector isnotusedsincephaseinformation isofno interesttothenoncoherent radar.Thelocaloscillator ofthenoncoherent radardoesnothave toheasfrequency-stahle asinthecoherent MTI.Thetransmitter mustbesufficiently stable overthepulseduration toprevent beatsbetween overlapping groundclutter,butthisisnotas severearequirement asinthecaseofcoherent radar.Theoutputoftheamplitude detector is followed byanMTiprocessor suchasadelay-line canceler. Thedoppler component con­ tClilledillthealllplituue nuctuations mayalsobedetected byapplying theoutputofthe amplitude detector toanA-scope. Amplitude fluctuations duetodoppler produce abutterfly modulation similartothatinFig.4.3,butinthiscase,theyrideontopoftheclutterechoes. 
 TO 
 The latter isusually tobepreferred. 3.Tomatch theimpedance ofacable. Inthis usethecable sees R, inparallel with the internal impedance ofthe circuit proper. 
 AES-3,pp.366-373, Nov.1967. 54.Hatcher, J.L.,andC.Cash:Polarization AgilityforRadarGlintReduction, IEEERegioll3CUIII'I.'I1­ tion,Huntsville, Alabama, Nov.19-21,1969. 55.Locke,A.S.:"Guidance," pp.408-413, D.VanNostrand Company, Inc.,Princeton, N.J.,1955. 
 Errors in the aperture illumination may be classed as either systematic or random. The  former are predictable, but the latter are not and can only be described in statistical terms.  Examples of systematic errors include (1) mutual coupling between the elements of an array,  (2) aperture blocking in reflector antennas due to the feed and its supports, (3) diffraction at  the steps in a zoned-lens antenna, and (4) periodicities included in the construction of the  antenna. 
 The signal is sampled by the A/D converter at frequency Fs, producing the  time sequence x n( ) and frequency spectrum X( )ω centered at frequency w0 with the  image centered at −w0. The A/D converter output signal is then frequency shifted by  complex multiplication with the reference signal ej n−w0, corresponding to a reference  signal rotating at w0 radians per sample, centering the signal spectrum X( )w about  zero. The unwanted image is re-centered at −2w0 if w0 > p /2 or −2w0 + 2p  if w0 ≤ p /2. 
  GENERATES SEVEN PULSES hIN FLIGHTv SIMULTANEOUSLY !T THE BEGINNING OF SUCH A DATA COL 
 A reflector system  such as this can effectively provide electronic scanning over a narrow FOV . However,  this type of array-fed reflector architecture does suffer from one drawback. A parabola  converts a spherical wave into a pure plane wave only when the source (feed) is at the  focus. 
 At each sever, the power traveling in the reverse direction is  dissipated in the sever loads without seriously affecting the power traveling in the  forward direction. The sever loads may be placed external to the tube to reduce dis - sipation within the RF structure itself. The efficiency of a TWT is usually less than  that of a klystron because of the loss due to the attenuation of the severs, as well as  by the presence of relatively high RF power over an appreciable part of the entire  structure. 
 Anderson, D. B.: A Microwave Technique to Reduce Platform Motion and Scanning Noise in Air­ borne Moving-Target Radar, IRE WESCON Co11v. Record, vol. 
 OUT NULLS 4HEN  THE ORIGINAL WEIGHTS ARE PERTURBED TO PRODUCE NULLS IN THE DESIRED DIREC 
 This isdone byilluminating, atany one. 24 THERADAR EQUATION [SEC. 2.5 time, anarrow radial strip extending outward from, forexample, the point directly beneath theaircraft and rotating or“scanning” this strip about avertical axis (see Fig. 
 TIIE 1'1.1:CJRONICAI.I.Y SITFRl'D PIIASED ARRAY ANTENNA IN RADAR 319  angle from hroadside; therefore, heyond some angle the radiation pattern will be dominated  by the error-produced sidelobes.) The shape of the main beam and the near-in sidelobes are  relatively unaffected by errors. although their magnitudes are modified. Note that the factor P,,  can also be used to evaluate the effect of random thinning of array antennas. 
 Deterministic antenna patterns with nulls steered in specific directions can  be achieved by modifying the weights at each element. These modified weights can  be either the amplitude and phase of each element or only the phase of each element.  Regardless of whether amplitude and phase nulling or phase-only nulling is used, the  weights at each element are not time-varying for deterministic RF nulling. 
 POLARITY RADAR CAN SET UP THIS CONDITION BY THE SIMPLE EXPEDIENT OF LOOKING DOWN ON A HORIZONTAL SURFACE DURING A CALIBRATION EXERCISE $ISCREPANCIES IN EITHER AMPLITUDE OR PHASE WILL BE EVIDENT FROM SUCH DATA COLLECTED OVER A RANDOM DIS 
 TRAL EMISSIONS OUTSIDE THE NOMINAL RADAR BANDWIDTH &OR THESE REASONS  CONFIGURATIONS EMPLOYING SEPARATE TRANSMIT AND RECEIVE ANTENNA SITES ARE EMPLOYED IN RADARS SUCH AS *INDALEE  */2.  AND 2/4(2  USUALLY IN A QUASI 
 The average input impedance isusually inthe range of400 to1000 ohms. Very small changes inanode potentials produce large changes inanode current. For example, the performance chart ofa4J31 magnetron (Fig. 
 The expected radar cross section of clutter can be expressed as the product of a reflectivity factor and the size of the volume or area of the resolution cell. For surface clutter, as viewed by a surface-based radar, a = Aca° = *eazya° (15.7) where <j is the average radar cross section, in square meters; Ac is the area of clutter illuminated, in square meters; R is the range to clutter patch, in meters; 6az is the one-way half-power azimuthal beamwidth, in radians; c is the speed of propagation, 300 million m/s; T is the half-power radar pulse length (after the matched filter), in seconds; and cr° is the average clutter reflectivity factor, in square meters per square meter. For clutter that is airborne, such as chaff or rain, 5 = V^ = /?eaz#yn (15.8) where V0 is the volume of clutter illuminated, in cubic meters; H is the height of clutter, in meters (if clutter fills the vertical beam, then H = /?6el, where 6el is the elevation beamwidth); and -q is the clutter reflectivity factor, in square meters per cubic meter. 
 Stoddard: An Analysis of Conical Scan Antennas for Tracking, IRE Natl.  Cmw. Record, vol. 
 Operation in the region of the sink, however, is not always desirable since it.J1as poor fre­ quency stability. Poor pulse shape and mode changes might result. The low-power region,  where the magnetron is lightly loaded, is called the antisink or opposice-si11k region. 
 D" QUANT!$ AMP NOISE  AA¤ ¦¥³ µ´    WHERE  ;3MAX.=D"    MAXIMUM INPUT PEAK SINUSOIDAL LEVEL RELATIVE TO RMS NOISE  D"  .!$ AMP     NUMBER OF AMPLITUDE BITS NOT INCLUDING SIGN BIT  IN THE !$  CONVERTER   ;NOISE=QUANTA    RMS THERMAL 
 Optimum bandpass filtering should  FIGURE 6.13  I/Q demodulator with gain, phase, DC offset, and time-delay adjustmentsIn-phase  power  dividerIF  SignalI/Q Demodulator  Reference  (COHO) +90ºA/D 90º  hybrid φ0ºDigital  I Data Digital  Q DataI Gain Q GainQ Phaseφ I Phase∆tA/D Sample  Clock  + A/D∆tA/D Sample  Clock I Offset D/A +Q Offset D/ALowpass  Filter  Lowpass  Filter ch06.indd   33 12/17/07   2:03:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 Target aspect feature extraction and application frommulti-aspect high resolution SAR. In Proceedings of the 2017 IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Fort Worth, TX, USA, 23–28 July 2017; pp. 1784–1787. 
 The lower the  intended frequency of operation, the more expensive the absorber becomes. Absorber  reflectivity ratings of −50 dB are common among the materials used. This perfor - mance is usually achievable only with the pyramidal design.56 Early indoor chambers were rectangular in shape, and despite the installation of  good absorbent materials on the walls, RCS measurements could be contaminated  by wall reflections. 
 If the target is in motion, Rand the phase cf, are continually changing. A change  68 . CW AND FREQUENCY-MODULATED RADAR 69  in cf, with respect to time is equal to a frequency. 
 pp. 660 665, St.:pti.:m­ ber, 1965.  29. 
   SINCE THE S 4HE ONLY APPARENTLY SUCCESSFUL APPLICATION OF STEP 
 THETIC APERTURE  THUS PRODUCING  SYNTHETIC APERTURE RADAR 3!2   4HIS OVERVIEW IS  BASED ON 3ULLIVAN AND #UTRONAo MORE DETAILED TREATMENTS ARE ALSO PROVIDED IN  THE LITERATUREn £Ç°£Ê  - Ê*,  * 
 When 0 = " the  doppler frequency is maximum. The doppler is zero when the trajectory is perpendicular to  the radar line of sight (0 = 90").  The type of radar which employs a continuous transmission, either modulated or unmod-  ulated. 
 111. C. J. 
 39-42) . TABLE 10.7 Paired-Echo and Weighting Transforms (Continued) layed and advanced from it by nlB s, scaled in amplitude by bn!2, and opposite in polarity. Comparison of Weighting Functions. 
 RANGE REQUIREMENT IS DUE TO MAIN 
 LOBE CLUTTER %VEN WITH 34!0  SIDELOBE CLUTTER IS A MAJOR LIMITATION   "OTH SIDELOBE  AND MAIN 
 ITY TO AGREE LOOSELY WITH THE OBSERVED POLARIZATION RATIOS OF SEA CLUTTER RETURNS  AND IN &IGURE   AS IN &IGURE   THE DATA WERE COMPARED TO THE PREDICTIONS OF THE 30- PURE  "RAGG MODEL AND THE TWO 
 47. G. F. 
 Spherical reflectors. Irtheparaboloid renector isreplaced byaspherical-reflector surface. itis possible toachieveawidescanning anglebecauseofthesymmetry ofthesphere.However, a simplespherical reflector doesnotproduceanequiphase radiation pattern(planewave),andthe pattern isgenerally poor.Thetermspherical aberratioll isusedtodescribe thefactthatthe phasefrontofthewaveradiated byaspherical reflector isnotplaneasitiswithawave Iadiatcd byallidealparabolic reflector. 
 Hansen, p. 561, May, 1971.  60. 
 IEEE, vol. 54, pp. 633 640, April, 1966. 
 (Optimum is not a  synonym fo.r best; it means the best under the given set of assumptions.) Maximizing the  signal-to-clutter ratio over all doppler frequencies, which leads to the binomial weights and  sin" 1tf& T filters, is not necessarily a pertinent criterion for design of an MTI filter since this  criterion is independent of the target signal characteristics. 3-5 It would seem that the MTI  filter should be shaped to reject the clutter at d-c and around the prf and its harmonics, but  have a flat response over the region where no clutter is expected. That is, it would be desirable  to have the freedom to shape the filter response, just as with any conventional filter. 
 This is especially important for radar equipped  with adaptive techniques since they might not be always fully modeled in a simulation  as they are in the real-world environment in which they must operate. The Radar Equation in Jamming and Chaff Conditions.  An example of radar  range performance under noise jamming is reported on pp. 
 THE TASK AHEAD  I: THE PRECEDING CHAPTERS WE HAVE WATCHED THE  fundamental points of radar, and have seen how the  basic systems work. Now we can study in more detail  the systems developed since the War, and look ahead to  the new tasks facing radar. It must be remembered,  however, that the picture is rapidly changing. 
 Ahighlydirective antenna viewinga distributed sourceofradiation under"ideal"conditions wouldreceiveanoisepowerequalto kTRB,wherek=Boltzmann's constant, TR=brightness temperature ofthesource,and B=bandwidth ofthereceiver. By"ideal"conditions ismeantanantenna withnegligible sidelobes andnegligible resistive losses,andwhichlooksatadistributed sourceofbrightness temperature (thecosmicnoise)intheabsence oftheearth'satmosphere oranyother sourceofnoise.Forapractical antenna theantenna temperature isdefined astheintegral ofthebrightness temperature overallangles,weighted bytheantenna pattern. Atmospheric absorption noise.Itisknownfromthetheoryofblackbody radiation thatany bodywhichabsorbs energyradiates thesameamountofenergythatitabsorbs, elsecertain portions wouldincrease intemperature andthetemperature ofotherportions would decrease.56Therefore alossytransmission lineabsorbs acertainamountofenergyandrera­ diatesitasnoise.Thesameistrueoftheatmosphere sinceitalsoattenuates orabsorbs microwave energy.Theradiation arisingintheatmosphere (oranyotherabsorbing body) mustjustcompensate forthepartialabsorption oftheblackbody radiation. 
 Raindrops arespherical, ornearlyso,butaircraftarecomplex targets.Tilusthe backscattered energyfromrainandaircraftwillbeaffected differently bythepolarization 01 theincident radarenergy.Advantage canbetakenofthisdifference toenhance thetarget-to­ clutter ratio whentheclutterbackground isprecipitation. Thisisaccomplished hyutilizing a radarwithcircular polarization orwithcrossedlinearpolarization. Acircularly polarized waveincident onaspherical scatterer isreflected asacircularly polarized wavewiththeopposite senseofrotation andisrejected bytheantenna thatorig­ inallytransmitted it.Withacomplex targetsuchasanaircraftthereflected energyismoreor lessequallydivided between thetwosensesofrotation sothatsometarget-echo energyis accepted bythesameradarantennathattransmitted thecircularly polarized signal.Thisisthe basisfortarget-to-c1utter enhancement usingcircular polarization. 
 WAVE ECHOES   NONSPECULAR MATERIALS HAVE THE OPPORTUNITY TO REDUCE THE BUILDUP OF SURFACE CUR 
 The range can be calculated from the duration ∆t and the speed of propagation  co:  € c0⋅Δt=2R⇒R=c0⋅Δt 2 (4.1)   For very precise range measurements the genuine speed of propagation (influenced by air pressure,  moisture, etc.) is to be used instead of co.  The resolution in the range depends on the time steps of  the timer (e.g. 1 ns = 30 cm). 
 Figure 8.17 (AN/SPS-48) shows a stack of slotted waveguides  for forming a bearn that is frequency-scanned in elevation. The slotted guides forming the rows  of the antenna are so~netimes called sticks. The power coupled out of the guide by the slot is a  function of the angle at which the slot is cut. 
 Alberty, “The WSR-88D and the WSR-88D Operational Support Facility  [Now Radar Operations Center],” Bull. Am. Meteorol. 
 SENSING APPLICATIONS &)'52%     'ENERAL CHARACTERISTICS OF SCATTERING COEFFICIENT VARIATION  WITH ANGLE OF INCIDENCE AFTER & 4 5LABY  2 + -OORE  AND ! + &UNG  &)'52%     2EGRESSION OF AVERAGE OF ALL  
 When there is no retarding effect, the cross-polarized energy causes  the antenna to drive off target in one of the quadrants of the two-axis angle-tracking  coordinate system, depending upon the direction of the initial error that moved the  source off the precise on-axis position.4,51 A solution used with missile-range-instrumentation radar, where target aspect  changes can cause a linearly polarized beacon to rotate to a cross-polarized aspect,  is to provide a circular polarization tracking capability. Coupling a linearly polarized  signal to a circularly polarized antenna results in a 3 dB signal loss, but it is indepen - dent of the direction of the linear polarization when rotated about a line in the direction  toward the radar. Troposphere Propagation. 
 BAND RADARS IS TO INCLUDE THE  EFFECT OF THE GROUND IN THE ANTENNA PERFORMANCE CHARACTERIZATION  AND THAT CON 
 1982 ,3, 59–65. 39. Main Climatic Characteristics and Typical Weather Event of Fuoshan. 
 ch19.indd   6 12/20/07   5:37:49 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 
 //"  3IDE 
 (Photograph courtesy of Westinghouse Electric Corporation.} . The power combining for each output cabinet consists of 56:1 combiners. The reactive power combiner consists of seven groups of 8:1 combiners fabricated in air stripline using 0.5-in ground-plane spacing. 
 Until 1945 there were 3000 engineers and scientists employed there.   Listed below are simply a few more important dates from Germany’s Radar developmen t:  1940 "Würzburg C", 200 MHz, 3 m ø, 4000 Unit   1941 "Würzburg Riese" 7,5 m ø, ±10', 1500 Unit (Figure 1.4)   1942 "Mannheim", 12 kW, automatic analysis   1942 "BordRadar Lichtenstein", 150 MHz, 15000 Unit   After the war year the development of Radar systems en tered a long pause.  Noteworthy ho w- ever, is that in 1946 the USA succeeded in reception of echoes from the Moon with a modified apparatus from the "Würzburg Riese" series. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 9.2 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 in the beam. 
 MEDIUM 02&S HAVE INHERENTLY GOOD DOPPLER VISIBILITY SINCE THEY ARE AMBIGUOUS IN SIGN ONLY   SO THE SPAN OF THE 02&S IN A SET OF . 02&S IS USUALLY MUCH LESS THAN AN OCTAVE !DDITIONAL CONSTRAINTS ON 02& SELECTION FOR BOTH WAVEFORMS INCLUDE GOOD VISIBILITY IN SIDELOBE CLUTTER WHERE SOME 02&S MAY BE OBSCURED BY CLUTTER IN PORTIONS OF THE AMBIGUOUS RANGE INTERVAL  AND MINIMIZATION OF GHOSTS IN THE AMBIGUITY RESOLUTION PROCESSING $OPPLER !MBIGUITY 2ESOLUTION  2ESOLUTION OF THE UNAMBIGUOUS DOPPLER 
 HAND SIDE IN INCREMENTS OF  MM  'ROUND  SURFACE IS SHOWN AS A VERTICAL LINE #OURTESY )%% 0$        2 r &)'52%  ,AYOUT OF TRANSMISSION LINE MODEL COURTESY )%%                        4!",%  ,AYER #HARACTERISTICS FOR 4RANSMISSION ,INE -ODEL ,AYER 2ANGE IN -ETERS 2ELATIVE $IELECTIC #ONSTANT ER,OSS 4ANGENT -ATERIAL      !IR       ,OSSY LAYER     !IR VOID       3UB BASE    7ET BASE INFINITE   7ET BEDROCK. 
 FIG. 25.5 Geometry for bistatic doppler. Target Doppler. 
 In IF sampling receivers, digital filtering is usually the primary means of setting the  final receiver bandwidth and provides anti-alias rejection required to prevent aliasing  in the decimation of the I/Q data rate. Digital filtering can be precisely controlled,  tailored to almost any desired passband and stop band rejection requirements. The  digital filters used are typically linear phase FIR filters, but they can also be tailored to  compensate for variations in the passband phase and amplitude responses of RF and  IF analog filters. 
 14). Pulse com- pression waveforms (Chap. 10) are used when the resolution of a short pulse but the energy of a long pulse is desired. 
 Table 7.1 lists some of the properties of the radiation patterns produced by various  aperture distributions.1 The aperture distributions are those which can be readily expressed in  analytic form and for which the solution of the inverse Fourier transform of Eq. (7. to) can be  conveniently carried out. 
 This technique iscalled “search- lighting.” Even with centimeter wavelengths, beamwidths attainable with antenna reflectors ofpracticable size (afew degrees) are large in comparison with the accuracy desired inthe measurement ofelevation angle (about atenth ofadegree) forheight-finding purposes. Therefore, target height isnot usually determined bydirecting the beam atthe target simply bymaximizing theecho. Instead, arrangements aremade forshifting the beam rapidly inele- vation angle byanamount which may be,typically, athird ofabeam- width, and comparing the echo signal received inone position with that intheother. 
 One aperture distribution which has been  considered in the past' is [l - (r/ro)2]P, where p = 0, 1, 2, . The radiation pattern is of the  form J, + ,({)/tPt '. When p = 0, the distribution is uniform and the radiation pattern reduces  to that given above. 
 (2) Circuit losses on the input, before the first stage, degrade the noise figure of the design; therefore some designs utilize off-chip matching. (3) A low noise-figure re- quires a bias condition that is close to the pinch-off voltage of the FET. Both gain and noise figure are highly dependent on the pinch-off voltage when the FET is bi- ased close to pinch-off. 
 70  Part of this is probably due to the difficulty in obtaining quantitative measurements and the  variability of rain with time and from one location to another. One form of Eq. ( 13.20) that has  been widely accepted is  Z = 200r1·6 ( 13.21)  where Z is in mm6/m3 and r is in mm/h. 
 513 13.11 Angle Indices .......................514 13.12 Range and Height Indices; Synchronization 518. xvi CONTENTS DISPLAY SYNTHESIS .........................524 13.13 The Design ofA-scopes. ,524 13.14 B-Scope Design ......................528 13.15 Plan-position Indicator. 
   3%! #,544%2  £x°ÎÇ SCATTERING PROPERTIES WITH NUMERICAL CALCULATIONS  AND THEN GOING TO THE WAVE TANK  TO VERIFY THE SCATTERING BEHAVIOR FOR REAL WATER WAVES %RICSON ET AL GENERATED A  STATIONARY BREAKER IN A SMALL FLOW TUNNEL AND COMPARED ITS SCATTERING PROPERTIES WITH A SPECULAR POINT CALCULATION #OAKLEY ET AL  SET UP A HYDROFOIL IN A POWERFUL WATER  CHANNEL  GENERATING A LARGE BREAKING WAVE FRONT THAT PRODUCED RADAR RETURNS CONSISTENT WITH ,AMBERTS ,AW  ALONG WITH THE POLARIZATION RATIOS IMPLIED BY MULTIPATH REFLEC 
 SEC. 6.9] EARLY AIRCRAFT-WARNING RADAR 181 flying aircraft, this simple, mgged equipment proved highly satisfactory inservice use. Itwmtb.edh-ectf orerunnero ftlwlaters hipbornelong- range air-search radar equipments (SA, SCand itsvarious redesigns, SK and itsredesigns) used onlarge ships until theend ofthe war. 
 The detection performance discussed previously is based on the assumption that the target is centered in the moving window. In the real situation the radar scans over the target, and decisions which are highly correlated are made at every pulse. Hansen9 analyzed this situation for N = 2, 4, 8, and 16 pulses and<a) MOVINGWINDOW (b) FEEDBACKINTEGRATOR (°) TWO-POLEFILTER W BINARYINTEGRATOR W BATCH PROCESSORINTEGRATEK PULSES, THEN DUMPBINARY INTEGRATOR . 
 Groundwater extraction will increase the ﬂuctuation of groundwater levels. That results in the compaction of highly compressible soft soils and the dissolution of carbonate rocks or suffusion processes. Therefore, land subsidence occurs. 
 RELATIVE REFERENCE FRAMES 4HE POSITION OF THE DISPLAY CURSOR IS ALWAYS AVAILABLE IN A DATA BOX IN TERMS OF RANGE AND BEARING FROM OWN SHIP ANDOR LATITUDE AND LONGITUDE COORDINATES )T IS THIS CURSOR THAT IS USED TO SELECT AND DE 
 All radar components are potential sources of distortion which canDOPPLER SHIFT FIG. 10.17 Peak sidelobe level versus doppler shift for linear FM. FIG. 
 Thismayappeartoresultinlowaperture utilization orpoorefficiency sincethetotalphysical areaisnotrelatedinasimplemanner,tothegainasitisinafullyilluminated antenna. However, thecostofthefixedreflectoroftheparabolic torusisrelatively cheapcompared with antennas whichmustbemechanically scanned. Nonutilization oftheentireaperture is probably nottooimportant aconsideration whenoverallcostandfeasibility aretakeninto account. 
 2&5) β (Model No. 1) β (Model No. 3)α (Models No. 
 5.3, and the schematic, shown in Figure 5.4, may be con- sidered typical for a packaged multichip 100-W L-band transistor. FIG. 5.2 Transient thermal response of a Class-C-biased silicon power transistor for a pulsed RF input.JUNCTION TEMPERATURE (0C) Pulse Envelope Short Term Duty Cycle: 50% Long Term Duty Cycle: 10% Cold-Plate Temperature: 35 deg C TIME (/us) . 
 TIONAL TO THE VARIANCE OF THE DOPPLER SPECTRUM AND INVERSELY PROPORTIONAL TO THE NUMBER  OF INDEPENDENT SAMPLES   RF 4 .OTE ALSO THAT VAR } VIS PROPORTIONAL TO  K  INDICATING  THAT  FOR THE SAME PROCESSING TIME  4 AND FOR THE SAME  RV  THE VARIANCE OF THE ESTIMATE  CAN BE REDUCED BY REDUCING THE WAVELENGTH  WHICH INCREASES THE  NUMBER OF INDEPEN 
 DiCaudo. REFERENCES  1. J. 
 It was further concluded from analysis of the operational logbooks that listening devices had ﬁrst been introduced for U-boats operating in the Bay of Biscay in June 1942 and their use in that area was more or less universal by September 1942. For the Gibraltar area it was concluded that they had been introduced in November1942, with fairly universal use by January 1943. In fact it was later determined that prototypes of the U-boat warning receiver, FuMB 1 Metox R 600 A, were ﬁrst introduced in August 1942 and that by the end of the year almost all U-boats had itinstalled [ 2]. 
 Both uniform distributions and modified Taylor  distributions were considered. The amplitude and phase distributions were described by the  gaussian distribution and were assumed independent of one another. An example of Leichter's  results for a uniform amplitude distribution is shown in Fig. 
 18, 1957, General Electric Company, Schenectady, N.Y. 10. Urkowitz, H.: The Effect of Antenna Patterns on Performance of Dual Antenna Radar Moving Target Indicators, IEEE Trans., vol. 
 BEAM JAMMING MAY BE MORE OF A THREAT TO 3!2 THAN SIDELOBE JAMMING u !DAPTIVE ARRAYS 4HE REFERENCES n DEAL WITH THE REJECTION OF A BARRAGE NOISE  JAMMING USING AN ADAPTIVE SPATIAL NULLING %QUIPPING THE 3!2 SYSTEM WITH AN ANTENNA PARTITIONED INTO SEVERAL SUB 
 PA. IEEE Cat. no. 
      
 # TO  #  /N SMALL CRAFT  THE DISPLAY AND RADAR PRO 
 SURFACE HEIGHT 33(  CORRESPONDS TO THE  MIDPOINT OF THE WAVEFORMS LEADING EDGE  SIGNIFICANT WAVE HEIGHT 37(  TO THE SLOPE OF THE LEADING EDGE  AND WIND SPEED 73  TO THE INVERSE  BACKSCATTERED POWER 4HE WAVEFORMS DEPICTED HERE ARE IDEAL 
 Afurther manipu- lation ofEq. (4a) isofinterest. Suppose the minimum power required forsatisfactory detection, Smin, isknown; wemay solve Eq. 
 Summary ofIndicator Type s.-Many considerations enter into thechoice ofthedisplay geometry. Inathree-dimensional problem, the designer must decide how todivide thecoordinates between two displays, orhow topresent alltheinformation onasingle display, ifthis isfeasible. Even atwo-dimensional display iscomplicated, and often involves con- flicting requirements, such asthe need forhigh resolution inangle and range ]vithout sacrifice inthe total field of~iew. 
 Because identical geome- tries with differing permittivities do not occur in nature, this distinction is not easy to measure. Effective permittivity for ground targets is very strongly influ- enced by moisture content, since the relative permittivity of liquid water is from about 60 at X band to about 80 at S band and longer wavelengths whereas most dry solids have permittivities less than 8. Attenuation is also strongly influenced by moisture, since wet materials usually have higher conductivity than the same materials dry. 
  3%, 
 63, pp. 1651-1660, December, 1975.  54. 
 I. Skolnik (td.), McGraw-fiill  Book Co., New York, 1970.  59. 
 Blackband (ed.). Gordon and !Jreach.  New York. 
 To jam this type of  radar effectively, the radar’s angle-tracking-error-sensing circuits must be captured  with a false amplitude-modulated signal, at the scanning or lobing rate, which is  significantly out of phase with that from the target return. When the conical-scan  or lobing modulation is imposed on both the transmitter and the receiver beams, it  is relatively simple for a jammer to synthesize the appropriate jamming signal by  inverting and repeating the transmitter modulation (inverse-gain repeater).154 This  can be partially overcome by a conical scan-on-receiver only (COSRO) system,  where the tracking radar radiates a nonscanning transmitting beam but receives with  a conical-scan beam. The jammer then has no knowledge of the phase of the coni - cally scanned receiving beam and must adopt a trial-and-error method of scanning  the jamming modulation until a noticeable reaction occurs in the tracking radar  beam. 
 TOR FEED MODELING  IE  INTEGRATED WITH REFLECTOR ANALYSIS  AND RIGOROUS MODELING OF ELECTRICALLY SMALL SCATTERERS  EG  SMALL SUBREFLECTORS OR FEED SUPPORT STRUTS #OMPUTER #ODES FOR 2EFLECTOR $ESIGN AND !NALYSIS  ! NUMBER OF COMMER 
 58. Bridges, J., and J. Feldman: An Attenuation Reflectivity Technique to Determine the Drop Size Distribution of Water Clouds and Rain, J. 
 Theantenna sees thecosmicnoiseatatemperature Tcwithanintervening absorbing atmosphere atatempera­ ture1'.1andalossL.l•Theatmosphere maybecharacterized forpresentpurposes byasingle temperature andasingleloss,butitcanbesubdivided, ifdesired,intoanionospheric compo­ nent,anoxygencomponent, andawater-vapor component. Thecombined temperature of cosmicnoiseandatmospheric noise[1;+(Lal-1)'r..]iscalledthespacetemperature, the brightness temperature, orthearltemta temperature ofanidealantenna. TheRFlossesLrr indicated inthefigurearemeanttoincludetheantenna, radome, andduplexer losses,aswell astransmission-line loss.Theeffective noisetemperature ofthereceiver isdenoted 1;e. 
 reflectors mounted near thereceiving antennas. These reflectors could beswitched inoroutofcircuit byremote control from theground. From their effect onthe echo, the operator could deduce whether the target was infront oforbehind thestation. 
 189. Proceedings of International Symposia on Tropospheric Profiling , 1998–present. 190. 
 The radar frequency is downconverted  to an IF, where filters with suitable bandpass characteristics are physically realiz - able. The mixer itself and the preceding circuits are generally relatively broadband.  Tuning of the receiver, between the limits set by the preselector or mixer bandwidth,  is accomplished by changing the LO frequency. 
 Digital control of the noise  injection is synchronized with the STC attenuation to provide an effective constant  noise level at the A/D converter input. Gain Control Components.  Most modern radars perform gain control digitally. 
   
 NOISE CASES 6 ELOCITY %STIMATION  4HE VARIANCE OF THE MEAN FREQUENCY ESTIMATE OF THE DOPPLER  SPECTRUM IS   VAR}    F04F3 F FD F R  ¯      4HIS IS AN INTERESTING RESULT SHOWING THAT THE VARIANCE OF THE ESTIMATE }F IS A FUNC 
 STORAGE DEVICE DOES NOT DISCHARGE DURING AN ARC  SO WHEN THE FAULT HAS CLEARED  THE TRANSMITTER CAN RESUME OPERATION IN MICROSECONDS .   4(% 2!$!2 42!.3-)44%2   £ä°Óx ! SOLID 
 ALARM RATE IN THE IMMEDIATE AREA OF THE !)3 
 If the radiation pattern of the feed is known, the illumina­ tion of the aperture can be determined and the resulting secondary beam pattern can be found  by evaluating a Fourier integral or performing a numerical calculation. The radiation pattern . (I) 0  D  >- V, -5 C  OJ ... 
 K7 3 
 L. J.: " Radar Meteorology." Uttiversity of Chicago Press. Chicago, 1959. 
 7.7. If one wished to obtain relatively  uniform illumination across a paraboloid aperture with a feed of this type, only a small  angular portion of the pattern should be used. An antenna with a large ratio of focal distance  to antenna diameter would be necessary to achieve a relatively uniform illumination across the  aperture. 
 ERROR INFORMATION 4HE LOG )& PERFORMS ESSENTIALLY AS AN INSTANTANEOUS !'#  GIVING THE DESIRED CONSTANT ANGLE 
 Phillips, W. E. Brown, Jr., S. 
 The switch shown in Fig. 6.14 is a hydrogen thyratron, but it can also be a mercury  ignitron, spark gap, silicon-controlled rectifier (SCR), or a saturable reactor. A gas tube such  Charging  impedance storoge element  Energy  some - -  Figure 6.13 Basic elements of one type  Charging path' \ Discharge path of radar pulse modulator. 
 NIQUES AS DESCRIBED LATER IN THIS CHAPTER 4O ILLUSTRATE THE OPERATING PRINCIPLES OF A SKYWAVE RADAR  &IGURE  PRESENTS A  MAP SHOWING MULTIPLE SURVEILLANCE TASKS ASSIGNED TO A HYPOTHETICAL RADAR WITH  n  AZIMUTHAL COVERAGE &IVE SECTORS OF CURRENT SURVEILLANCE ACTIVITY ARE SHOWN  EACH ADDRESSING A PARTICULAR MISSION AS INDICATED  EACH MISSION CONSISTING OF A NUMBER OF DWELL INTERROGATION REGIONS $)2S  4HE ELECTRONICALLY STEERED RADAR TRANSMIT BEAM STEPS THROUGH THESE $)2S  IN SOME ASSIGNED SEQUENCE  ILLUMINATING EACH $)2 WITH AN APPROPRIATE WAVEFORM FOR A CORRESPONDING INTERVAL DURING WHICH THE RECEIVING SYSTEM ACQUIRES A COHERENT TIME SERIES OF ECHO SAMPLES 4HE COHERENT I NTEGRATION TIME #)4   DEPENDS ON THE TYPE OF OBSERVATION BUT IS ALMOST ALWAYS IN THE RANGE OF n SECONDS %ACH TRANSMITTER FOOTPRINT IS ANALYZED BY FORMING SIMULTANEOUS CONTIGUOUS RECEIVE BEAMS  ON THE ORDER OF  n WIDE AT  -(Z IN THE CASE OF THE 53 .AVY 2/4(2 AND  THE !USTRALIAN *INDALEE AND */2. RADARS  WHICH EQUATES TO A  KM CROSS 
 Accuracy and Stability of Carrier Frequency. In an oscillator-type transmit- ter, the RF power tube determines its own operating frequency, as opposed to having it determined by a separate low-power stable oscillator. The frequency may thus be affected by tube warmup drift, temperature drift, pushing, pulling, tuner backlash, and calibration error. 
 3/* 3IMILARLY 4ABLES  AND  REPORT THE RESULTS IN THE PRESENCE OF 2'0/  WITHOUT AND RESPECTIVELY WITH ! 
 Marton, Academic Press, Inc., New York, 1978, pp. 203-252. Also Trunk, G. 
 105. A. Schmidt, V . 
 Onthe other hand, thefluctuations inthesecond case areonly about 1percent and are therefore negligible compared with system instability.. SEC,,16.9] TARGET i71SIBILITY 649 Consider howalimitingr eceivershouldbe adjusted ineach ofthese cases. Since only thephase part ofthefluctuation isselected, thefluctua- tion ofthevideo output is1/v’2 or3dbless than thetotal input fluctua- tion, Thus the figure –22dbbecomes –25dbatthe output, which means that the rms fluctuation inthe first case isabout ~ofthelimit level, Therefore, inorder toobtain aPPI with uniform background, the gain control ofthe receiver, ahead ofthe limiting stages, should be adjusted sothat rms noise isalso ~oflimit level. 
 179-186.  April, i%2.  88. 
 Count  sampler Radar  receiver Pulse. Binory  counter Ronge gate  No. 1 + Video - Quantizer Threshold  detector i  388INTRODUCTION TORADAR SYSTEMS 10.7AUTOMATIC DETECTION Thefunction oftheradaroperator viewing theordinaryradardisplay istorecognize the presence oftarge.tsandextracttheirlocation. 
 < l, the  standard deviation of the clutter doppler spectrum a, for a single-frequency MTI is increased  to rr,( 1 + r2 )1 '2 in a two-frequency MTI. (This assumes that the clutter-velocity spectrum  width a,. is the same for both carriers, or a1 = ra2 where 111 and 112 are the clutter doppler­ frequency spreads. 
 Thecharacteristics ofclutterwill bedescribed aswellasthevariousmethods forreducing theirharmful effectswhenthey interfere withthedetection ofdesiredtargets. Echoesfromthelandortheseaareknownassurfaceclutter,andechoesfromrainor otheratmospheric phenomena areknownasvolumeclutter.Becauseofitsdistributed nature, themeasure ofthebackscattering echofromsuchclutterisgenerally givenintermsofa 470. radar-cross-scctioli cl~+rt~ity rntlier tliali tlic r;1C1;1r cross st'cfioli as was described for convcn-  tiorla1 targets in Scc. 
 (a) ( b)  Figure 3. Other popular models. ( a) Alexnet model. 
   (& /6%2 
 SIGNAL SPECTRUM IS OBTAINED BY LAYING COPIES OF THIS PAGE END 
 8,Vol. 24)and onecanobtain, forexample, the results displayed inTable 2.1below, TABLE 2.1.—PROBABILITY OFNOISE EXCEEDING SIGNAL-PLUS-NOISE Tn 7J=10-1 1 50 2 3.0 4 1.0 8 –0.8 16 –2.5 32 –4.2 64 –5.9~=10–2 8,9 6.7 4.6 2.7 0.8 –1.1 –2.910.9 8.6 6.5 45 2.5 05 –1.4rfj=10-4 ~=lo+ ~=10-O 12.3 13,3 14.2 9.9 10.8 11.6 7.7 8.6 9.3 5.7 6.5 7.3 3,7 4.5 5,2 1.6 2.5 3,2 –0.4 0.4 1.1 The entries inTable 2.1arethestrength ofasignal, indecibels, rela- tive tothe average noise power Po. The number n,atthe left, isthe number ofsweeps averaged—for example, 4inthe case ofFig. 
 16. Farnett, E. C., T. 
 7ESLEY 0UBLISHING #OMPANY   AND  6OL )))   .ORWOOD  -! !RTECH (OUSE    & 4 5LABY AND - # $OBSON   (ANDBOOK OF 2ADAR 3CATTERING 3TATISTICS FOR 4ERRAIN   .ORWOOD   -! !RTECH (OUSE  . £È°xn  2!$!2 (!.$"//+   - 7 ,ONG   2ADAR 2EFLECTIVITY OF ,AND AND 3EA  ND %D  .ORWOOD  -! !RTECH (OUSE    2 . #OLWELL  $ 3 3IMONETT  * % %STES  & 4 5LABY  ' ! 4HORLEY  ET AL   -ANUAL OF 2EMOTE   3ENSING  ND %D  6OLS ) AND ))  &ALLS #HURCH  6! !MERICAN 3OCIETY OF 0HOTOGRAMMETRY    & - (ENDERSON AND ! * ,EWIS   -ANUAL OF 2EMOTE 3ENSING  0RINCIPLES AND !PPLICATIONS OF  )MAGING 2ADAR  6OL   RD %D  .EW 9ORK *OHN 7ILEY  3ONS    * 2 ,UNDIEN  h4ERRAIN ANALYSIS BY ELECTROMAGNETIC MEANS RADAR RESPONSES TO LABORATORY PREPARED  SOIL SAMPLES v 53 !RMY 7ATERWAYS %XP 3TA  42  
 Harmer and O'Kara22 show a variant of the equipment that may be used with a single antenna plus a duplexer. This would be very attractive, especially for an airborne radar that must fit into a small radome. Unfortunately, experience has shown that there is a limit to the transmitter power that may be employed in such . 
 Notice that the test also aims at discriminating the type of ECM being  active, i.e., SOJ or RGPO. In fact, whenever the noise jammer is in the antenna main  beam many false measurements with high jammer-to-noise ratio are induced; in this  case, it turns out that N > 2 and RGPO is declared inactive. Whenever the jammer is no  longer in the target’s line-of-sight, it may happen that multiple measurements exceed the  detection threshold, but the condition that the excess is greater than 3 dB will be very  unlikely to be fulfilled in practice. 
 The inclusion of such effects is given in Ref. 5. Equation (21.61) shows that the signal-to-noise ratio at the output of a radar that has used pulse compression and has generated a synthetic antenna has the following properties different from conventional radar: 1. 
 ch20.indd   7 12/20/07   1:15:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 23.6  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 where Bn is the noise bandwidth of receiver’s predetection filter. 
 HORN MULTIMODE FEED DESIGN 7HEN THERE IS A SIGNIFICANT TRACKING LAG OR DELIBERATE BEAM OFFSET FROM THE TARGET   THE ERROR R TO  DUE TO RECEIVER NOISE FOR A GIVEN 3.2  IS GIVEN BY THE EQUATION   SS Q QTT , ",K  ;   =    WHERE P,   LAG ANGLE  SAME UNITS AS  P"  ,   ANTENNA SUM 
 Hollandse Signaalapparaten B.V . advertisement, Def. Electron ., vol. 
 Resulting expressions for power (scattering coefficient) variations appear in  Table 16.1. Correlation coefficient Power Expression Reference eL −ξ2 2/ KeLhsin( / ) tan θσ θ −2 2 22 Davies61 eL −| |/ξKAθ θ θθ θ cos s insin cos/ 22 43 2 1+  −V oronovich5TABLE   16.1  Scattering Coefficient Variation ch16.indd   10 12/19/07   4:54:45 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 (From peters,16 IRE I'rans.)  down the length of the object and reflect from the discontinuity at the far end. This gives rise to  a traveling wave component that is not predicted by physical optics the~ry.*~,~'  An interesting radar scattering object is the cone-sphere, a cone whose base is capped with  a sphere such that the first derivatives of the cone and sphere contours are equal at the join  between the two. Figure 2.1 1 is a plot of the nose-on radar cross section. 
 The ReBP algorithm takes the advantages of the accuracy and the expandability for analyzing the atmospheric propagation. Furthermore, the parallelization can be used in ReBP process to improve the computational efﬁciency. In this paper, the modiﬁed two-steps scintillation simulator is merged into the ReBP process to exactly accommodate the observation geometry of sliding spotlight mode and derive the SAR raw echo. 
 Also, theamount ofseareturn isasteadily decreasing function ofrange. Itispossible todevise acircuit that lo\vew thereceiver gain immediately following thetransmitter pulse and then increases it~teadily, arriving at maximum gain atthe time the sea return has disappeared. This is kno~vn asa“sensitivity y-time-control (STC) circuit”; ithas the disad- vantage that controls must beprovi{ded toadjust itforvarying seacondi- tions. 
 SEC.1311] ANGLE INDICES 515 bright narrow line isproduced atagiven azimuth. The electrical impulse necessary todothis can beprovided inany ofseveral ways. 1.The simplest method involves the use ofmechanical contractors onthe scanner oronany mechanical repeater ofthe scanner motion. 
 ATE VALUES FOR MODERATE BISTATIC SCATTERING GEOMETRIES   R n VV  R nHV y R nVH   R nHH  AS  ILLUSTRATED IN &IGURE  %Q  IS OF FUNDAMENTAL IMPORTANCE TO MANY (& RADAR APPLICATIONS  INCLUDING SHIP  DETECTION  REMOTE SENSING SEE FOLLOWING SECTION   WAVEFORM SELECTION  AND OTHER RADAR MANAGEMENT FUNCTIONS &OR EXAMPLE  &IGURE  SHOWS A MEASURED DOPPLER SPEC 
 49. R. J. 
 Figure 5. Process of the proposed KA-DBS processing approach. In Figure 5, ﬁrst, range migration corrections and range compression are utilized to process the raw echo data. 
 M. Banhart (ed.), Remote Sensing Laboratory Publication List 1981–1983 , V ol. TR-103,  Lawrence: University of Kansas, Remote Sensing Lab., 1984. 
 They state that the radar determined storm cumulative precipitation  measurements are expected to be accurate within a factor of 2 for 75% of the time.  Accuracies over large areas can be improved to about 30% with the addition of a  surface rain-gauge network. Although radar measures reflectivity aloft, the primary  concern is rainfall estimation at the surface. 
 Thehigh-power capability oftheklystron, likeanything else,isnotunlimited. Oneofthe majorfactorswhichhasrestricted thepoweravailable fromklystrons hasbeentheproblem of obtaining RFwindows capableofcoupling theoutputpowerfromthevacuumenvelope tothe load.Otherfactorslimiting largepowersarethedifficulty ofoperating withhighvoltages, of dissipating heatinthecollector, andofobtaining sufficient cathode emission current. Examples. 
  
 Quarter-wave andHalf-wave Lines.—It can beshown that when aloss- less transmission line ofcharacteristic impedance Z,aquarter wavelength long isterminated inanimpedance 2,,theinput impedance is Zi=Z~/Zl. (1) This property iswidely used. For example, two transmission lines of differing impedance canbematched toeach other byjoining them through aquarter-wave line whose characteristic impedance isthe geometric mean ofthat ofthe two lines. 
 J. Zottl: The Detection Performance of the Siebert and Dicke-Fix CFAR Radar  Detectors, IEEE Trans., vol. AES-7, pp. 
 The circuit can readily beadapted tolarger cathode-ray tubes. For the3BP1 (3in.)itisonly necessary toalter the sawtooth-generator charging resistor tocompensate foraslightly different defection sensi- tivity. Amuch more intense display can beprovided byusing thesplit- accelerator type 3JP1. 
 Randall: The Cavity Magnetron, J. lnsc. Elect. 
 PULSE CANCELER COEFFICIENTS   n     THE OUTPUT RESIDUE APPEARS AS IN &IGUR E A 4HE CORRESPOND 
 TIONS IN THE DIELECTRIC PROPERTIES OF THE GROUND  OF THE ROUGHNESS OF THE GROUND AND  NATURE OF VEGETATIVE OR SNOW COVER  OF RADAR WAVELENGTH  AND OF ANGLE OF INCIDENCE 6IEWED AS AIDS TO INSIGHT  RADAR GROUND 
 F. Kretschmer, “Angle measurement in the presence of mainbeam interference,”  Proc. of IEEE 1990 Int. 
 Breit and Tuve’s method of working, discovered  soon after the Appleton ionosphere team had started,  was soon adopted as an alternative and a somewhat  more convenient means. But throughout all the Radio  Research Board work a cathode-ray tube, now a common  piece of apparatus in almost every radar set and in every  television set—but, of course, a scientific novelty in the  early 1920’s—was used to time the radio waves, and  thus to ascertain the heights of the various ionized  layers.  By timing the pulses of radio energy shot skyward it  was found that the ozonosphere layer of atmosphere  wraps itself around the surface of the globe at a distance  away from the surface of about fifty miles, that the  height of the Heaviside layer varies from sixty to eighty  miles, that the ionosphere proper starts about a hundred  miles up, and that the so-called ‘F,’ or Appleton, layer,  as it came to be Known after the head of the little team  of British scientists who discovered it, ranges from a  hundred and forty to some three hundred miles up. 
 Losses (  Lp, Ls): The loss term Lp contains the two-way losses along the path   traversed, including ionospheric absorption and ground-reflection losses; Ls repre - sents any radar system losses. Ionospheric losses, while predicted on a statistical  basis, can constitute a major unknown in real-time radar operation. Range (R): The range in Eq. 
 51Gaseous discharge. orplasma. phaseshiftersarebasedon thevariation ofthedielcctric constant ofthegaseous medium asafunction ofthenumberof freeelectrons, whichdepends onthecurrent through thedevice.5l53Although theycan handleaboutI kWofpowerandcanbeadapted toawiderangeoffrequcncies. 
 107. 011, L. L., and C. 
 MINED BY THE MAXIMUM RANGE OF INTEREST  +   #%),;2MAX F2 C=  2ANGE CORRELATION  OCCURS WHEN THE UNFOLDED DETECTIONS ARE SCANNED AND A CORRELATION WINDOW IS APPLIED ACROSS LOOKS  AS SHOWN IN &IGURE  )N THIS EXAMPLE  THE CORRELATED TARGET RANGE HAS AN AMBIGUITY NUMBER OF  TH TIME AROUND ECHO  ON 02&   AND AN AMBIGUITY     $ $"  
 VIA was also being planned, with the new scanner being manufactured by Metropolitan Vickers, with 100 unitsdue for 31 March 1944. The principle features of ASV Mk. VI were an increase of peak transmitter power from 40 kW to 200 kW and the use of an attenuator to reduce the transmitted power doi:10.1088/978-1-6432-7066-1ch4 4-1 ªMorgan & Claypool Publishers 2018. 
 587-595, December 1986. 21. Taylor, A. 
 ING  THESE SYSTEMS ARE TERMED  SCATTEROMETERS 3UCH SYSTEMS MAY USE #7 SIGNALS WITH  OR WITHOUT DOPPLER PROCESSING  BUT THEY MAY ALSO USE BOTH PULSE AND &- TECHNIQUES . £È°Óä  2!$!2 (!.$"//+  3CATTEROMETERS CAPABLE OF MEASURING RESPONSE OVER A WIDE RANGE OF FREQUENCIES ARE  CALLED SPECTROMETERS 6ARIOUS ANTENNA PATTERNS FROM PENCIL BEAMS TO FAN BEAMS MAY  BE USED 3YSTEMS TO MEASURE THE FULL POLARIZATION MATRIX MUST USE VERY CAREFUL ANTENNA DESIGNS SO THAT THE PHASES OF THE DIFFERENT TRANSMITTED AND RECEIVED POLARIZATIONS ARE WELL CONTROLLED  AND LEAKAGE BETWEEN POLARIZATIONS IS THOROUGHLY SUPPRESSED #7 AND &- 
 large concentrations of  insect angel echoes would not be expected outside this temperature range. As with clutter due  to birds, sensitivity time control (STC) can reduce the adverse effects of clutter due to insects.  Clear-air turbulence. 
    
 This error  can be corrected by lobe switching; that is, by periodically switching the antenna beam a small  amount in the y-direction at a low rate (perhaps 20 Hz)." TWO displaced doppler-frequency  spectra are produced at the two antenna positions. A narrow tracking filter tracks the cross-  over of the two spectra. The frequency of this crossover is the same for water as for land. 
 The centering ofthePPI can beadjusted bysetting the potentiom- eters controlling the clamping points. Ifextreme off-centering moves theamplifier grids out oftheir normal operating range, adelay occursat thebeginning ofthesweep which gives theeffect ofavirtual center atthe desired point. Byusing anextrernel yhigh-voltag esawtooth, off-center- ing ofasmuch assixtoeight tube radii has been provided. 
 TO 
       !     " &)'52%  4APER EFFICIENCY  SPILLOVER  BLOCKAGE  AND TOTAL LOSS VS FEED PATTERN EDGE TAPER                        
 PLANE SPACING 4HE  K7 OUTPUTS OF THE TWO  COMBINERS WERE COMBINED IN A SINGLE  ISOLATED HYBRID THAT WAS MANUFACTURED BY USING A COAXIAL TRANSMISSION LINE 4HE ADVERTISED LOSSES OF THE  AND  COMBINERS WERE  D" AND  D"  RESPECTIVELY 2!-0 , 
 52. Alday. J. 
 The results show that the simulated images are consistent with actual SAR images. The effects of different radar parameters and wind ﬁelds on SAR eddy imaging are analyzed by qualitative and quantitative methods. Overall, the simulated images produce a surface pattern and brightness variations with characteristics resembling actual SAR images of oceanic eddies. 
 Sensors 2016 ,16, 869. [ CrossRef ][PubMed ] 19. Mittermayer, J.; Moreira, A.; Lo ﬀeld, O. 
   
 20. L. J. 
 cc ¯¯TT T T  TTD   &ILTER FREQUENCY RESPONSE (F    9F 8F    %ULERS IDENTITY   EJJQQQ  COS SIN4!",%    3IGNAL !NALYSIS $EFINITIONS AND 2ELATIONSHIPS. 
 This same data can also be plotted in the form of constant-power-level contours, as shown in Fig. 6.1c. These contours are the intersections of a series of horizontal planes through the 3D pattern at various levels and can be quite useful in revealing the distribution of power in angular space. 
 In principle, inverse synthetic aperture radar can  be used to image moving targets such as aircraft and ships. It has been applied in the past to  imaging of the moon and to mapping the surface below the clouds surrounding the planet  Venus.61  Polarization. 46•47 The polarization of the radar backscattered energy depends on the target  properties and differs, in general, from the polarization of the energy incident on the target. 
 NENT FOR THE ANTENNA IS COMPRISED OF A  /HM COAX  FEEDING A TAPERED PARALLEL PLATE WAVEGUIDE WITH A WIDTH OF  MM AND A HEIGHT OF  MM ! TAPER ALONG THE WIDTH OF THE TOP PARALLEL PLATE IS USED AS A TRANSITION TO TRANSFORM A  /HM UNBALANCED LINE INTO A  OHM BALANCED LINE&)'52%   ( 
 Nothing but a narrow beam instead of the former ‘flood-  lighting’ could give the desired results, and this meant  much higher power on much shorter wavelengths, with  much higher sensitivity of reception. Fortunately Britain  was well placed to deal with this problem, and from  March 1939 some ninety of our leading physicists and  men who had spent many years in the abstruse problems  of splitting atoms and ‘spinning’ electrons were attached  to the coastal radar stations set up to guard Britain  against invasion. Their past experience had made them  aware of the need for centimetric radar. 
 SIBLE WITH ELECTRONIC SCANNING IN BOTH AZIMUTH AND ELEVATION IMPORTANT REGIONS EG   THE HORIZON  MAY BE EMPHASIZED AT WILL AND SEARCHED MORE FREQUE NTLY 4HE RADAR MAY  OPERATE WITH A HIGHER THAN NORMAL FALSE 
 Section 3derives the new EMAM method. Section 4discusses the performance of the proposed method. In Section 5, the validity of the proposed method is veriﬁed based on the computer simulations and the real airborne data. 
 8815–8827, 1995. 106. W. 
 Their use is also not practical in short-range radar or with high-duty  cycle wavefor~ns like those used in some pulse-doppler radars, since the switcltiiig het~cc~i tile  two states is too slow.  The value of remanent magnetization is aflectect by temperature. Telnperati~rc clla~igcs  may be due to microwave dissipation in the ferrite as well as ambient-temperati~re variations. 
 [ CrossRef ] 24. Tang, Y.; Zhang, B.; Xing, M.; Bao, Z.; Guo, L. The Space-Variant Phase-Error Matching Map-Drift Algorithm for Highly Squinted SAR. 
 AP-13, pp. 303-310, March 1965. 40. 
 160 HOW RADAR WORKS  the pilot to complete his landing visually in all but the  worst weather conditions.  Babs has the advantage that it was used throughout  the War with confidence, and many other branches of  beaconry have developed from Babs technique; it is  therefore a well-tried radar equipment and popular  with crews who have been taught the drill on this type  of radar aid. It also has the advantage that it is inter-  national, presents no language difficulties, and is reliable  owing to its simplicity. 
 From50to80percentofthed-cinputpowermightbeconverted toheat intypicallinear-beam tubes,andmostofthisheatappears atthecollector. Therefore the majority ofthecoolingrequired intheklystron isatthecollector. Powerisextracted from theoutputcavityanddelivered totheloadbyacoupling loop(asshowninFig.6.9)for low-power tubes,orbywaveguide inhigh-power tubes.Awaveguide ceramic window is necessary tomaintain thevacuum inthetubeandyetcouplepoweroutefficiently. 
 The same holds for SAR imaging from ground-based platforms, airplanes and Unmanned Aerial Vehicles (UAVs). This editorial paper reviews the content of the special issue dedicated to SAR techniques and applications, by presenting advances on SAR signal modelling, SAR simulation, SAR processing, SAR image analysis and SAR-based applications. 2. 
 Walter: Traveling-wave Slot Antennas, Proc. IRE, vol 41.  pp. 
 CRATE COVERING FOR THE INTAKES THAT  IN THEORY  PREVENTS APPROACHING RADAR WAVES FROM ENTERING THE INLET DUCTS  WHERE THEY RATTLE AROUND AND EVENTUALLY COME BACK OUT AGAIN  HEADING DIRECTLY BACK TO THE RADAR  "ECAUSE THE EGG 
 With a phased array divided into two  overlapping subarrays, a constant pulse repetition frequency can be used and the horizontal  separation of the two overlapping subarrays can be controlled electronically to compensate for  platform motion. However, it is possible to change the effective phase center of a rellt.ctor  antenna by employing two feeds to produce two squinted overlapping beams, as in ati  amplitude-comparison monopulse radar (Sec. 5.4). 
 50, pp. 703–724, 1988. 20. 
 WD  B  )N COMPLEX FORMAT   %% EHHJH D  AND %% EVVJV D  )F WE TAKE C    CV n CH AND SET CV    AS A REFERENCE  WE CAN WRITE  %% E %HJ VV 
 TER  THE COLD -9 ICE SCATTERS MUCH MORE THAN COLD &9 ICE )N SUMMER   R   FOR -9 ICE  DECREASES TO ABOUT THE SAME LEVEL AS THAT OF &9 ICE &IGURE  SHOWS THIS AND TYPI 
 FIELD PATTERN IS (V}   POLARIZED IN THE DIRECTION }V   THEN THE  INCIDENT ( 
 However, radars make detections in polar coordinates (range, angle, doppler), while  target motion is most likely linear in Cartesian coordinates ( x, y, z). Therefore, some  compromises must generally be made in selecting a coordinate system for filtering.  Table 7.5 describes the design tradeoffs for different selections. 
 4  The decay of the visual information displayed on the CRT should be long enough to allow  the operator not to miss target detections, yet short enough not to allow the information  painted on one scan to interfere with the new information entered from the succeeding scan. '  However, there is usually not sufficient flexibility available to the CRT designer to always  obtain the desired phosphor decay characteristics. The brilliance of the initial " flash " from the  CRT phosphor may be high, but the afterglow is dim so that it is often necessary to carefully  control both the color and the intensity of the ambient lighting to achieve optimum seeing  conditions. 
 ABLE RECEIVE 
 I12 ;\nimportant conclusion isthatthedetailsoftheradiation pattern, especially inthe regionoutsidethemainbeam,aremorelikelytobedetermined bytheaccuracy withwhichthe antenna isconstructed thanbythemanner inwhichtheaperture isilluminated. Thus themcchanical cngineer andtheskilledmachinist andtechnician arejustasimportant as theantenna designer inrealizing thedesiredradiation pattern. Effectsofphaseshifterquantization.R2.115 Thediscrete valueofphaseshiftthatresultsfrolll theuseofquantized phaseshiftersintroduces an"error" inthedesiredaperture illumination. 
 97. R. Klemm (ed.), Applications of Space-Time Adaptive Processing , London, UK: IEE Radar, Sonar  and Navigation, Series 14, 2004. 
 Anexample ofaRiekediagram foracoaxialmagnetron isshowninFig.6.7.Ilis obtained byvaryingthemagnitude andphaseoftheVSWRoftheRFload,withthefrequency andthepeakcurrentheldconstant. TheregionofhighestpowerontheRiekediagram iscalled thesinkandrepresents thegreatest coupling tothemagnetron andthehighestefticiency. Operation intheregionofthesink,however, isnotalwaysdesirable sinceitJlaspoorfre­ quencystability. 
 OTHER RADAR TOPICS S47  arc short compared to the time diffen:ncc ,,.. For a llal earth. I.he l1eighl of the target is  approximately  I _ cRt,,  r, -2/ra ( 14.27)  where r velocity or propagation. 
 Lett ., vol. 4, pp. 170–171, May 3, 1968. 
 This is often made possible by radar coverage requirements having reduced range at wide elevation angles.SQUARERELATIVEGAIN (dB) . FIG. 6.16 AN/TPS-43 multiple-beam antenna. 
   '2/5.$ %#(/  £È°{£ FOR THIS PURPOSE -OST OF THE SPACEBORNE 3!2S THAT FOLLOWED 3EASAT HAVE BEEN USED IN  SOIL 
 Ulsamer, E.: ATS-6, NASA's Huge Transmitter in the Sky, Air Force Mag., vol. 57, August 1974. 51. 
 2, pp. 93–102,  April 1994. 75. 
 12 1314 15 16 17 18 19 BKM BKM 098765432 ISBN O-OT-QSVTIB-X The editors for this book were Daniel A. Gonneau and Beatrice E. Eckes, the designer was Naomi Auerbach, and the production supervisor was Dianne Walber. 
 64 timing equipment. The displays aresometimes subclassified interms of theparticular type ofelectronic marker used (see Fig. 6.2). 
 DOPPLER CELL TO  PROVIDE A SPECIFIED FALSE REPORT TIME IS   0.4 M N..4RD FM&! &- &2 ¤ ¦¥³ µ´¤ ¦¥ ¥ ¥¥³ µ´ ´ 
 FERENCE  MAKING DO WITH hCLEARv CHANNELS BETWEEN OTHER USERS 0ATTERNS IN 3PECTRUM /CCUPANCY  7HEN THE (& BAND IS SCANNED WITH A SPEC 
 change with changing target aspect.  Amplitude fluctuations of the echo signal are important in the design of the lobe­ switching radar and the conical-scan radar but are of little consequence to the monopulse  tracker. Both the conical-scan tracker and the lobe-switching tracker require a finite time to  obtain a measurement of the angle error. 
 5.8, the phase-locked filter," or the phase-locked  loop.  If, in any of the above techniques, moving targets are to be distinguished from stationary  objects, the zero-doppler-frequency component must be removed. The zero-doppler-frequzncy  component has, in practice, a finite bandwidth due to the finite time on target, clutter tlirctt~a-  tions, and equipment instabilities. 
 Some early systems employed noncoherent pulse waveforms, but they are not suitable for operation in clutter (except for very large target cross sections). Coherent PD systems, however, can approach the performance of CW. The motivation for the use of PD in the seeker was to simplify the illuminator in air-to-air systems. 
 Much of  the interest in adaptive antennas has been to reduce the effects of noise jamming in the antenna . TIii' l'I.ITTRONICAI.I.Y STl'ERED l'IIASED ARRAY ANTENNA IN RADAR 333  sidelobes. The ideal adaptive antenna acts automatically to adjust itself as a matched  (spatial) filter by reducing the sidelobes in the direction of the unwanted signals. 
 Tech ., 17, pp. 1596–1608, 2000. 49. 
 Barton, CW and  Doppler Radars,  Section IV-12, V ol. 7, Norwood, MA: Artech House, Inc., 1978, pp. 303–312. 
   39.4(%4)# !0%2452% 2!$!2   £Ç°ÓÎ -OVING 4ARGETS IN A 3!2 )MAGE $ISPLACEMENT OF A -OVING 4ARGET  4HE BASIC THEORY OF 3!2 ASSUMES THAT THE  GROUND SCENE  IS STATIONARY ! MOVING TARGET IN THE SCENE WILL  HAVE A hWRONGv RELA 
 The wide variety and complexity of terrain and what grows or is built  upon it, makes it difficult to formulate a satisfactory theoretical model to describe tlie back-  scatter from land. Adding to the difficulty are the effects of weather, time of day, and scason, as  l'able 13.2 Weibull clutter parameters"  -- - - . ---. 
 1977. 25.Barrick. D.E..J.M.Headrick. 
 Warfare , vol. 7, pp. 59–61,   May–June, 1975. 
 It  seems that those slow-wave structures best suited for broad bandwidth (like the helix) have  poor power capability and poor heat dissipation. A sacrifice in bandwidth must be made if  high-power is required of a TWT. If the bandwidth is too small, however, there is little  advantage to be gained with a traveling-wave tube as compared with multicavity klystrons. 
 The second focus of this chapter is to describe the computer modeling of the propa - gation factor. For ease of computations in early solution techniques, the propagation  factor was often taken as unity, a condition representing free space. With computer- implemented propagation models, however, the assumption of free space need no  longer be a limiting factor. 
 GENCE OF A GRATING LOBE INTO REAL SPACE 4HEREFORE  IT MAY BE EXPECTED THAT WHEN A GRAT 
 THERADAR EQUATION 59 forcomputing scanning lossissimilarinprinciple tothatforcomputing beam-shape loss. Scanning losscanbeimportant forrapid-scan antennas orforverylongrangeradarssuchas thosedesigned toviewextraterrestrial objects.Asimilarlossmustbetakenintoaccount when covcring ascarchvolulllewithastep-scanning pencilbeam,aswithaphasedarray, ~Rsincenot allregionsofspaceareilluminated bythesamevalueofantenna gain. Limiting loss.Limiting intheradarreceivercanlowertheprobability ofdetection. 
 Tlie radar cross section may he  expressed as n = t', oi, where Vm is the volurne of the radar resolution cell. The volume V',  occupied by a radar beam of vertical beamwidth 4,, horizontal beamwidth O,, and a pulse  of duration r is approxirnately  wtiere c. = velocity ofpropagatioti. 
 E., and R. E. Millett: A Double-Slot Radar Fence for Increased Clutter Suppression, IEEE  Trans., vol. 
 J.M.Headrick. andR.W.Bogle:Directional SeaSpectrum Determina­ tionUsingHFDoppler RadarTechniques. IEEETraIlS..vol.AP-25.pp.4-11.January. 
 *"= ^P(P ~ l " 2/)r " l ~ ^Vj for p even where P, n, and i are as defined above for the Frank code. For P = 3, the phase sequence is O, -2ir/3, -4ir/3, O, O, O, O, 2ir/3, 4W3. Generation and processing of polyphase waveforms use techniques similar to those for the FM waveforms of Sec. 
 5.7~. The sum patterns is used for  transmission, while both the sum pattern and the difference pattern are used on reception. The  signal received with the difference pattern provides the magnitude of the angle error. 
 Frush, “Rapid-scan doppler radar development considerations, Part II:  technology assessment,” in 21st Conf. Radar Meteorol.  AMS, Boston, 1983, pp. 
 Asinseveral other system developments involving great advances over previous equipment, requirements onthis set were not firmly specified during thedevelopmental stage. Inmany respects this freedom from rigid requirements was advantageous. General objectives were clear, the design men were well situated todraw freely foradvice and help oncomponent specialists and onmen familiar with operational needs, and theywere largely free tousetheir own ingenuity and judgment to meet themany problems that were presented. 
 r  rr    ¯[      ]99 9 ; u    WHERE N IS THE UNIT SURFACE NORMAL ERECTED AT THE SURFACE PATCH  D3 AND Y IS THE 'REENS  FUNCTION  9 ERIKRP   . £{°£n  2!$!2 (!.$"//+  4HE DISTANCE  R IN %Q  IS MEASURED FROM THE SURFACE PATCH  D3 TO THE POINT AT  WHICH THE SCATTERED FIELDS ARE DESIRED  WHICH COULD BE ANOTHER SURFACE PATCH 4HESE  EXPRESSIONS STATE THAT IF THE TOTAL ELECTRIC AND MAGNETIC FIELD DISTRIBUTIONS ARE KNOWN OVER A COMPLETELY CLOSED SURFACE  3 AS INDICATED BY THE LITTLE CIRCLE ON THE INTEGRAL  SIGN   THE FIELDS ANYWHERE IN SPACE MAY BE COMPUTED BY SUMMING INTEGRATING  THOSE SURFACE FIELD DISTRIBUTIONS OVER THE ENTIRE SURFACE 4HIS SCATTERING PROBLEM RELIES ON THE SAME TWO EQUATIONS  BUT INSTEAD OF MEASURING THE TOTAL FIELDS OVER A CLOSED SURFACE SURROUNDING THE BODY  ONE DETERMINES THE FIELDS INDUCED ON THE  BODY SURFACES THEM 
 BEAM AZIMUTH AND RELATIVE RADAR AND TARGET VELOCITIES  AGAIN FOR AN UNFOLDED SPECTRUM 4HE ORDINATE IS THE RADIAL OR LINE 
 Anderson, “Simulation and modeling for the Jindalee over-the-horizon radar,” Math. and  Comp. in Simulation , vol. 
 A. Greenwald, K. B. 
 +1/"  4HE RADAR RANGE EQUATION OR RADAR EQUATION  FOR SHORT  NOT ONLY SERVES THE VERY USEFUL PURPOSE OF ESTIMATING THE RANGE OF A RADAR AS A FUNCTION OF THE RADAR CHARACTERISTICS  . 
 Interrogation pulses of 5 μs length were transmitted alternately from the left and right antenna, switching every 25 ms, so that 4 or 5 pulses were transmitted from each antenna in turn. The same antennas were used to receive the beacon responses, which were typically about 15 μs in length. The responses received were mixed into the radar IF ampli ﬁer and omni-directional responses displayed on the radar PPI. 
 Unfolded ranges (Ambiguous RG = 3.1)Unfolded ranges (Ambiguous RG = 8.9)Unfolded ranges (Ambiguous RG = 6.2)9 18 27 36 45 543.1 12.1 21.1 30.1 39.1 48.1D1 9 18 27 36 45 5418.9 28.9 38.9 48.9D2 8.9 Correlation window = ±0.3 Range Gates9 18 27 36 45 546.2 17.2 28.2 39.2 50.2D3 Blank bins occur when unfolded range falls outside of bin edgesPRF 2 = 10 RG/IPP PRF 3 = 11 RG/IPP PRF 1 = 9 RG/IPP Coarse bin size is set bythe shortest IPP = 9 RG FIGURE 4.18  Range correlation using coarse binning on unfolded, centroided ambiguous detections. In  this example, range gate size is the same for all three PRFs. ch04.indd   32 12/20/07   4:53:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 This means that C.must belarge, which may result inalarge capacity to ground and affect the high-frequency response. For example, al-~f condenser may have several hundred micromicrofarads ofcapacity toits shell. Mounting thecondenser oninsulating posts isfrequently necessary insuch cases. 
 This antenna proved tohave again of700; this meant that the reduction ofantenna gain would require about 3dbofthe calculated 10-db leeway between the AhT/APQ-13 and the AhT/APS-lO. The remaining 7dbcould beand were used topermit areduction inpulse power. The lightweight, low-voltage 2J42 magnetron (see Fig. 
 Surface finish aKecta value. fSpecification limit forcable alone. Connectors hrnit safe power toafew kilowatta. 
 It covered 214 –234 Mc/s. In both cases the aerials were located on opposite sides of the nose of the aircraft. 6.2 Lucero trials results Results of trials were reported by TRE in [ 3], using a Wellington aircraft with horizontal aerials (type 301). 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 12.6  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 where ˆvis a unit vector in the direction of interest. 
 9.3. This has also been called an image-enhanced  ntixer," or product return mixer.56 (It is similar to the image-reject rni~er~.'*"*~~ whose  purpose is to reject the image response.) The RF hybrid junction on the left of the circuit  produces a 90" phase difference between the LO inputs to the two mixers. The IF hybrid  junction on the right imparts another 90" phase differential in such a manner that the images  cancel, but the IF signals from the two mixers add in phase. 
 31. V. E. 
 Saatchi, and C. Bertoia, “Global ice and land climate  studies using scatterometer image data,” EOS, Trans. American Geophysical Union , vol. 
 RANGE GATED SYSTEM IS SIMPLY TO BLANK DETECTION REPORTS FROM THAT GATE 7HEN A -4) FILTER IS NOT USED  THE DOPPLER FILTER BANK FOR EACH RANGE GATE CAN BE EXAMINED TO DETERMINE IF THERE ARE ANY DETECTIONS DUE TO SPURIOUS SIGNALS FROM LARGE CLUTTER  WITH SUBSEQUENT EDITING OF THESE DETECTIONS IF THE MEASURED CLUTTER 
 C. Currie51 © IEEE 1974 ) ch15.indd   25 12/15/07   6:17:09 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Inthe case ofa shipborne setitispossible tocompensate forthe ship’s own motion and therefore toseeother ships and aircraft inthepresence ofsea-clutter and storm echoes. 16.2. Basic Principles ofMTI.—Two fundamental ideas areinvolved inthe solution ofthe MTI problem: first, amethod ofreception that responds differently tofixed and tomoving targets; second, anarrange- ment that takes advantage ofthis difference byselecting only themoving targets. 
 The most sensitive part of the anechoic chamber is the rear wall,  which receives 95 to 99 percent of the power radiated by the radar; hence, the best  absorber should be reserved for the rear wall.57 The floor, ceiling, and sidewalls also  contribute errors, via a quadruplet of reflections not unlike those due to the ground  plane of outdoor ranges. A remedy is the tapered anechoic chamber, which eliminates  most of the sidewall reflections purely by tilting portions of the walls, floor, and ceil - ing away from the chamber centerline.58,59,60 Even targets of modest size cannot be measured at the far-field distance in indoor  facilities because most chambers are not much more than 200 ft or so in length. It is  possible, however, to provide the necessary uniformity of illumination by collimating   the radiated beam. 
 The GEOS-3 spacecraft was an eight-sided aluminum shell topped by a truncated pyramid. The satellite width was 132 cm (53 in), and the height was 81 cm (32 in); the weight of the GEOS-3 was 340 kg (750 Ib). Type HI SBR. 
 ! AMPLIFIERS ARE THE  MOST LINEAR AS WELL AS THE LEAST EFF ICIENT (IGH DYNAMIC 
 The latter continues to function all the time  it is switched on, and, apart from the distortion intro-  duced by ‘detection,’ the job of the receiver amplifier  stages is to handle the sine-wave form and deliver at the  loud-speaker a continuous output which should be as  nearly as possible a mirror image of the microphone  _ Voltage wave-form at the transmitter. The process is  ‘continuous. Not so in the radar receiver. 
 269-270 Weather fix.507 Weibull probability density function: landclutter, 496 seac1uller,480 Weighting, fortimesidelobes, 426 Weinstock crosssectionmodels. 50 Whitening filter,375 Wing-beat frequency, bird,509 Within-pulse scanning, 314-316 byfrequency scanning, 302-303 in3Dradar.545 Wrap-up factor.299 X-rayhazard,466 Z,radarreOectivity factor,500-501 Zero-crossings detector. 384-385 Zoningoflenses,249,251. 
 This is called multilook mapping . When the maps are superimposed (i.e.,  when [the magnitudes of] successive returns from each resolution cell are averaged),  the effects of scintillation [i.e., speckle] are reduced” (p. 432).FIGURE 17.8  Principles of imaging the Washington Monument: For the geometry  shown, the optical image shows the side of the Monument on the same side as the shadow,  whereas the SAR image shows the side of the Monument on the opposite side of the  shadow. 
 CASE MAIN 
 1CHAPTER 1 — BASIC RADAR PRINCIPLES AND GENERAL CHARACTERISTICS INTRODUCTION The word radar is an acronym derived from the phrase RAdioDetection AndRangingandappliestoelectronicequipmentdesignedfordetectingand tracking objects (targets) at considerable distances. The basic principlebehind radar is simple - extremely short bursts of radio energy (traveling atthe speed of light) are transmitted, reﬂected off a target and then returned asan echo. Radar makes use of a phenomenon we have all observed, that of the ECHO PRINCIPLE. 
 imately twice the optimum size for the sum signal.7 Consequently, an interme- diate size is typically used with a signif- icant compromise for both sum and dif- ference signals. The optimum four-horn square feed, which is subject to this compromise, is described in Ref. 3 as based on minimizing the angle error caused by receiver thermal noise. 
 UNIT GRADIENTS VERSUS  . 
 Klemm (ed.), London: Springer,  2004, pp. 603–697. 137. 
 BORNE  WIDE SWATH SYNTHETIC APERTURE RADAR v  )%%% 4RANSACTIONS ON 'EOSCIENCE AND 2EMOTE 3ENSING  VOL   PP n    2 + -OORE  * 0 #LAASEN  AND 9 ( ,IN  h3CANNING SPACEBORNE SYNTHETIC APERTURE RADAR WITH  INTEGRATED RADIOMETER v  )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS   VOL !%3 
 Complex image after azimuth compression of the range compressed ISAR signal with –15 dB signal to noise ratio: ( a) ISAR image amplitude; ( b) ISAR image phase. Figure 9. Resulting complex image after 3rd additive summation of complex images: ( a) ISAR image amplitude; ( b) ISAR image phase. 
  RADAR v IN  0ROCEEDINGS OF THE  )%%%  VOL   ISSUE   &EBRUARY   PP n  " #ANTRELL  h!$# SPURIOUS SIGNAL MITIGATION IN RADAR BY MODIFYING THE ,/ v IN  0ROCEEDINGS OF  THE  )%%% 2ADAR #ONFERENCE  !PRIL n    PP n  ( (OMMEL AND ( &ELDLE  h#URRENT STATUS OF AIRBORNE ACTIVE PHASED ARRAY !%3!  RADAR   SYSTEMS AND FUTURE TRENDS v IN   )%%% -44 
 TRACK AND ALONG 
 193. Sensors 2019 ,19, 2161 Figure 10. The point array target used in simulation. 
 ERABLE EXPANSION ON AN INTERNATIONAL FRONT 4HIS SECTION PROVIDES AN OVERVIEW OF PROGRAMS KNOWN AT THE TIME OF PUBLICATION OF THIS (ANDBOOK  TO HAVE PROGRESSED THROUGH 0HASE !  WHICH IS EVIDENCE OF FUNDING THAT IS SUFFICIENTLY SERIOUS THAT MOST ARE LIKELY TO CULMINATE IN THE LAUNCH AND OPERATION OF A FLIGHT SYSTEM 4HE ARCHI 
 TERMINAL DEVICES  AND THIS FIGURE IS REFERENCED MULTIPLE TIMES IN SUCCEEDING SEC 
 Ani-fpulse originating either in thelocking-pulse mixer orinaseparate generator ismodulated, delayed and inject edinto the receiver channel. Thk same pulse locks the coherent oscillator. The delayed pulse ismodulated inphase and in m/From locking puls~ meter 7 ~50#sac delayline r I 90”phase shift PulsedCoherent30t4c/secoscillator mclllatorI J I L I FIG. 
 Pushing: The amount by which a magnetron's frequency varies with changes in anode current is called its pushing figure,10 and the resulting pulse- to-pulse and intrapulse frequency changes must be kept within system require- ments by proper modulator design. 8. Pulling: The amount by which a magnetron's frequency varies as the phase of a mismatched load is varied is called its pulling figure.10 Thanks to the ready availability of ferrite isolators, pulling is seldom a problem in modern radar . 
 Ferrimagnetic phaseshifters. Aferriteisamagnetizable metal-oxide insulator whichcontains magnetic ionsarranged toproduce spontaneous magnetization whilemaintaining gooddielec­ tricproperties.27-29Incontrast toferromagnetic metals,ferritesareinsulators andhaveahigh resistivity whichallowselectromagnetic wavestopenetrate thematerial sothatthemagnetic fieldcomponent ofthewavecaninteract withthemagnetic moment oftheferrite.This interactionresultsinachangeofthemicrowave permeability oftheferrite.ThetermJerrimag­ netismwasintroduced todescribe thenovelmagnetic properties ofthesematerials thatare nowknownasferrites. Ferrites havebeenderivedprincipally fromtwobasicmetal-oxide families: theferrimag­ neticspinelsandthegarnets. 
 680-685, September 1973. 24. Ahearn, J. 
 However, problems with design and manufacture meant that ASVMk. VIB had only just entered service with the ﬁrst of the Warwicks ﬁtted with it for No. 179 squadron in May 1945, as the war with Germany ended. 
 The coaxial magnetron improves on the classical  magnetron by providing greater reliability, longer life, and better stability.  RADAR TRANSMITTERS 191 (electromagnetic compatibility), andECCM (electronic counter-countermeasures) all influence thetypeoftransmitter selectedanditsmethodofoperation. Thechoiceoftransmit­ teralsodepends onwhether theradaroperates fromfixedlandsites,mobilelandvehicles, ships,aircraft,orspacecraft. 
 In the case of the sphere, the undulations in the resonance region are due to two  distinct contributions to the echo, one a specular reflection  from the front of the sphere  and the other a creeping wave  that circles around its shadowed side. The two go in and  out of phase as the sphere grows larger because the difference in the lengths of their  electrical path from source to receiver increases continuously with increasing ka. The  undulations become weaker with increasing ka because the creeping wave loses more  energy the longer the electrical path around the shadowed side. 
 Modern requirements for simultaneous precision tracking of multiple  targets has driven the development of the electronic scan array monopulse radar  with the capability to switch its beam pulse-to-pulse among multiple targets. The  AN/MPS-39 shown in Figure 9.1 b is an example of a highly versatile electronic scan  monopulse missile-range instrumentation radar. The principal applications of precision tracking radar are weapon control and   missile-range instrumentation. 
 TO 
 WIDTH  A FOUR 
 8.8.2  Digital Pulse Compression   With digital technology for pulse compression the transmitting signal is either amplitude or phase modulated, where as a rule the phase modulation is preferred because of the larger total  energy content of the signal.  T he two most used procedures employ the:  . Radar System Engineeri ng Chapter 8 – Pulse Radar  67       Binary Phase Coding (BPC) e.g.⇒ Barker Code   or  Multiphase Coding   e.g.⇒ Frank Code    8.8.3  Digital Pulse Compression with Barker Code   The Barker Code consists of a special sequence binary phase encoded signal with the dur ation  τ, as demonstrated in Figure 8.23. 
 Inthe L-scope, the signals from the two antennas produce deflections ofopposite sign, the range @m(a)Side-by-side presentation (K-scope). (b) Back-to-back presentation (L-scope). Signal returr, from theright lobeisthe Signal return from theright lobeisthe stronger. 
 BAND INTER 
 Probert-Jones, J. R.: The Radar Equation in Meteorology, Quart. J. 
 Thelatter isshown when narrow at aandwide atb.Asection through A-Aisshown inFig.9.21. 9.14. Schwarzschild Antema.-It isknown (Sees. 
 10. International Electrotechnical Commission, www.iec.ch. 11. 
 SAR Imaging The works in [ 1–6] concern several aspects of the SAR imaging. In [ 1], the authors propose a multi-angle SAR imaging system suited for an ultrahigh speed platform and based on multi-beamforming. By acquiring images at different angles during the same flight, the system allows better characterization of the target on the ground, as well as a simplified motion error compensation. 
 SCAN CORRELATION CAN IMPROVE THE TARGET 
 heen a Pictures are merely illustrative, and are not to be considered accurate m ae  to the grid of the CRT, so that the spot strobes itself and grows momentarily brighter as a signal is received. The Type B square is drawn out by the trace in the following manner, which is rather interesting to follow. The tracing-spot starts its journey at the bottom left corner of the CRT, and is moved up to the top left _ corner, Covering a distance equal to the maximum range of the radar equipment. 
 REFLECTED  SIGNAL PATHS  AS SHOWN IN &IGURE  !LTHOUGH THE FLUCTUATIONS IN  Q AND E ALTER THE ACTUAL TRACKING FROM THE THEORETICAL  THE  EQUATION GIVES A GOOD INDICATION OF THE ERRORS TO BE EXPECTED WHEN TRACKING A POINT SOURCE SUCH AS A BEACON (OWEVER  SKIN TRACKING OF AN AIRCRAFT AT LOW ELEVATION MAY RESULT IN A DEPARTURE FROM THE CLASSIC PERIODIC ERROR VERSUS ELEVATION  AS ILLUSTRATED IN &IGURE   BECAUSE OF AN INTERACTION BETWEEN TARGET ANGLE SCINTILLATION AND MULTIPATH ERROR THAT CAN CHANGE THE CHARACTERISTICS OF THE MULTIPATH ERROR 7HEN TRACKING A POINT SOURCE TARGET AT CLOSE RANGE  THE RADAR MAIN BEAM IS  ABOVE THE IMAGE  BUT THE IMAGE IS SEEN BY THE DIFFERENCE 
 These flybys will be targeted so that during each flyby a different region of Titan will be mapped with an SBR SAR. The Titan radar mapper will have a very wide swath (600 to 800 km) to obtain a global map during the small number of flybys. Real aperture imaging will provide a resolution of 6 to 40 km. 
 RADAR RECEIVERS  6.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 Seven particularly useful regions have been outlined on the chart. Use of the chart  is illustrated by means of the region marked A, which represents the widest available  spurious-free bandwidth centered at L/H = 0.63. The available RF passband is from  0.61 to 0.65, and the corresponding IF passband is from 0.35 to 0.39. 
 VI. The scanner could be rotated at up to 40 rpm or stopped and ‘inched ’to point at a target. In [ 9] the CCDU recommended a scanner speed of 30 rpm for normal search operations. 
 (3.2). The plus sign  associated with the doppler frequency applies if the distance between target and radar is  decreasing (closing target), that is, when the received signal frequency is greater than the  transmitted signal frequency. The minus sign applies if the distance is increasing (receding  target). 
 C Band (4.0 to 8.0 GHz). This band lies between the S and X bands and can be described as a compromise between the two. It is difficult, however, to achieve long-range air surveillance radars at this or higher frequencies. 
 The measurement  of noise ba11dwi<l1.h. however. involves a complete knowledge of the response characteristic  H(f ). 
 Just how the  tube works we shall see in a moment, in a subsequent  chapter. But for the present we can consider the tube  as being evacuated, leaving a nice empty space in which  there is a pencil of electrons which can be made to  sweep about over the screen end of the tube and trace  out a pattern on the fluorescent surface. The beam of  electrons can be made to sweep across or round the  screen, rather like the way in which the hands of a clock  sweep round the face. 
 DRIVE MOTORS  CONVENTIONAL ELECTRIC MOTORS  GEARED DOWN TO DRIVE THE ANTENNA  OR DIRECT 
 R. Ward, “A model environment for search radar evaluation,” in EASCON ’71 Convention  Record , New York, 1971, pp. 81–88. 
 8.23. The energy enters the  antenna elements, passes through the phase shifters, is reflected, and again passes back  through the phase shifters to be radiated. Like the lens array, the phase shifters apply a linear  pllase distributioti for beam steering and a correction for the curvature of the primary wave-  front from the horn. 
 ART RADAR ALTIMETERS CAN MEASURE THE RESULTING SLOPES TO A  
 be assumed ~ be h~~ween  the horizon and the antenna boresight. In the ex-trem~,-the-peak-fo-peak tracking error would  not exceed 0.7 to 0.8 beamwidth and typically the rrns error would be about 0.3 beamwidth. -~~- These relatively simple methods, combined with heavy smoothing of the error signal, can  allow meaningful, but not necessarily accurate, tracking at low angles. 
 3KY-ED 8 
 Fiz. (U.S.S.R ), vol. 28, no. 
 The variable i  will keep track of the processing stage  being performed and is initialized to  zero. The basic algorithm can perform a  phase shift between ±90o. If the desired  phase shift is outside of that range, the  input I and Q values are first negated,  imposing a 180o phase shift, and 180o is  subtracted from the desired phase shift. 
 government  agencies. In 1990, Willis used Weiner’s references to reconstruct and evaluate typical  data from Weiner’s work,89 which became available for public use in Willis.1,16 In 2003,  Weiner’s work89 was cleared for public release, making available in one document all  unclassified σB0 data and analysis through 1980. Weiner then updated his work with data  available through 2005 and republished it in Chapter 9 of Advances in Bistatic Radar.2  This section summarizes and comments on essential elements of Weiner’s work. 
 € Hnorm≡0 (2.16)  - Due to the consistency of the electric field Maxwell’s equations yield the following:   € ∂Htan ∂n=0 (2.17)   Where ∂/∂n demonstrates an identified existing tangential field Htan from the derivation  according to measuring standards. In Figure 2.2 the boundary conditions for the time independent  components are illustrated.   Σetan=etaninc+etanref=0 ∂htan/∂n=0 etaninc etanrefΣhnorm=hnorminc+hnormref=0 hnorminchnormref   Figure 2.2  Boundary conditions on a perfectly conducting surface (inc = incident, ref =  reflected)  . 
 It is very useful to consider the noise-equivalent sigma-zero (NE s  0), defined as the  level of s  0 that produces a received power equal to the thermal noise power, i.e., an  SNR of unity. We set SNR = 1 and have  NER kT F V P Grσπ ψ λ δ03 3 0 2 32 4 8= =( ) ( ) cos Loss Tx-avgπ π λ ψ η δR k T F V P Ar3 0 2 2( ) cos Loss Tx-avg (17.33) For example, if R = 200 km, T0 = 290 K, F = 2, Loss = 5, V = 180 m/s, y  = 10o, Pavg =  700 W, G = 34 dB, l = 0.03 m (X band), and dr = 0.3 m, then NEs  0 = −22 dB. A clear SAR image must have an SNR greater than about 5 dB. 
 When the second threshold is reached, one counts the number of consecutive pulses for which the second threshold is exceeded. When this number equals the third threshold, a target is declared. The performance of the MBMW and a comparison with the OBMW were given in Ref. 
 ( 11.8)] is given, except for an arbitrary constant factor, by  :;J a -:;J a  L.  "' >  OJ u  "' Cl'.: S (/) = j2nf S(/)  9 I Ni(/)12 (11.9)  /  Figure 11.3 Effect or noise n{t) in shifting the apparent zero crossing or the output s0(TR T0) or the  gating receiver of Fig. 11.2. 
 Conversely, for a given size of antenna, lower sidelobes mean less gain and a correspondingly broader beam width. The optimum compromise (tradeoff) between sidelobes, gain, and beamwidth is an important consideration for choosing or designing radar anten- nas. Figure 7.23 of Chap. 
 Quite early in the post-war years  there was hasty, ill-considered, and premature publica-  tion, on both sides of the Atlantic, of much material  purporting to tell how radar works and who made this  miracle possible. So vast is the radar field and so great  its potentialities that it is really to be wondered that there  was not even a bigger spate of tendentious material and  consequent wrangling. No amount of familiarity with  radar can blunt your appreciation of what has been  achieved; from the small beginnings of Appleton’s  . 
 /N 
                
 The polarization char- acteristics of a radar can be exploited as ECCM techniques in two ways. First, . the cross-polarized pattern (i.e., the orthogonal polarization to the main plane of polarization) of a radar antenna should be kept as low as possible consistent with radar system cost. 
 Digital frequency-domain pulse compression processing is performed.  ASR-12 Next-Generation Solid-State Air Traffic Control Radar.56  The ASR-12 ter - minal airport surveillance radar transmits a 55-µs pulse with peak power of 21 kW to  provide a single-pulse transmit energy of 1.16 J. Nonlinear frequency modulation is  used with a pulse compression ratio of 55 to achieve range-resolution equivalent to  an uncoded 1-µs pulse. 
 Stafford, “MESAR (Multi-Function, Electronically Scanned,  Adaptive Radar),” Proc. of Int. Conf. 
 Mass .. 1975. (A collec­ tion of 3R reprints on sea, land, and atmospheric clutter.)  37. 
 A. Shipley, and J. H. 
 71. L. B. 
 27.Woodward, P.M.,andI.L.Davies:Information TheoryandInverseProbability inTelecommunica­ tions,Proc.lEE,vol.99,pI.III,pp.37-44,March,1952. 28.Davies,I.L.:OnDetermining thePresence ofSignalsinNoise,Proc.IEE,pI.JII,pp.45-51,March, 1952. 29.Fuller,W.:"AnIntroduction toProbability TheoryandItsApplications," 2ded.,vol.I,p.114,John Wiley&Sons,Inc.,NewYork,1957. 
 (Courtes~ ofSpem~ Gwoscope Compang, Inc.) detail inconnection with another system but itshould benoted here that short-time frequent ystabilities ofthe order ofapart in10’0 must beattained ifthe system istowork with full sensitivity inthe presence ofground clutter. This requires careful attention tomicrophonics and topower-supply filtering. Also, the transmitter filament must hesup-. 
 For scattering features, it contains superstructure scattering features [ 7], three-dimensional scattering feature [ 8], radar-cross-section (RCS) [ 9], and symmetric scattering characterization (SSCM) [ 10], etc. As for classiﬁers, artiﬁcial neural networks (ANNs) [ 11] can establish a general classiﬁcation scheme by training, which makes it widely used in ship classiﬁcation. Support vector machines (SVM) [ 12] is also a popular model. 
 DIMENSIONAL 0HASE 5NWRAPPING 4HEORY  !LGORITHMS  AND 3OFTWARE    .EW 9ORK 7ILEY    2 'OLDSTEIN AND # 7ERNER  h2ADAR INTERFEROGRAM FILTERING FOR GEOPHYSICAL APPLICATIONS v  'EOPHYSICAL 2ES ,ETTERS  VOL   PP nn    * * VAN :YL  ( ! :EBKER  AND # %LACHI  h)MAGING RADAR POLARIZATION SIGNATURES 4HEORY AND  OBSERVATION v 2ADIO 3CIENCE  VOL   PP n    0 % 'REEN *R  h2ADAR MEASUREMENTS OF TARGET SCATTERING PROPERTIES v IN  2ADAR !STRONOMY    * 6 %VANS AND 4 (AGFORS EDS   .EW 9ORK -C'RAW 
 ................................ ....................  7  Elevation Angle  ................................ 
 V. Trunk, “Radar properties of non-Rayleigh sea clutter,” IEEE Trans ., vol. AES-8,   pp. 
 Makridis: Two-Frequency Secondary Radar Incorporating Passive Trans­ ponders, Electronics Letters, vol. 9, no. 25, pp. 
 since it provides more power gain than common-emitter operation at frequencies above approximately 1 GHz. Power Combining. To achieve very high levels of output power from a single port, combining the outputs of a large number of modules is required, and therefore a complex combining design is necessary. 
 At tile start of tracking the bandwidth is made wide and then it narrows down if the  target rnoves in a straight-line trajectory. As the target maneuvers or turns, the bandwidth is  wideried to keep the tracking error small.  The Kalrnan filter78 is similar to the classical a-p tracker except that it inherently pro-  vides for the dynamical or maneuvering target. 
 K. Barton, “Recent developments in radar instrumentation,” Astron. Aerosp. 
 DERIVED POLYPHASE 0# CODES v  )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONICS 3YSTEMS   VOL   NO  PP n  *ULY   7 7 0ETERSON AND % * 7ELDON  *R   %RROR #ORRECTING #ODES  #AMBRIDGE -)4 0RESS     APP #  - ) 3KOLNIK  )NTRODUCTION TO 2ADAR 3YSTEMS  RD %D  .EW 9ORK -C'RAW (ILL    P  . ,EVANON AND % -OZESON   2ADAR 3IGNALS  .EW 9ORK )%%% 0RESS  *OHN 7ILEY  3ONS  )NC     PP n  , "MER AND - !NTWEILER  h0OLYPHASE "ARKER SEQUENCES v  %LECTRONICS ,ETTERS   VOL   NO     PP n  .OVEMBER     7 
 22.12 Weight versus diameter for three generic antenna designs.47 precision required to operate as a spaceborne antenna. Both contractors devised orbiter-attached experiments that would maximize program outputs while mini- mizing orbiter and experiment risks. Although many flight configurations were designed, overall results were similar for both phased array and parabolic anten- nas. 
 D. J. McLaughlin, Y . 
 Any use is subject to the Terms of Use as given at the website. The Radar Transmitter. 10.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 Clustered-Cavity Klystrons . This is a good example of the technique of grouping  cavities to improve the operation of a klystron. 
 VECTIVE CELLS AND SURROUNDING PRECIPITATION  0HOTO  COURTESY  OF  ./!!.73  &)'52%     3 
 The tracker, usually implemented with a nine-state (position, velocity, and acceleration)  Kalman filter, estimates target motion in an inertial coordinate system. Multiple-Target Tracking  (MTT) can be accomplished in several ways. One  method ( Track-While-Scan , or TWS) is to use the normal search mode with FM or  multiple-PRF ranging and store the range, angle, and doppler of the reported detec - tions in the radar computer. 
 the number of pulses integrated, P,, and n,. (After ~arcum,'~ courtesy IRE  Trc~rrs.)  1,000r---------_ t--- 100 ----------I-I- 10 100 1,000 n,number ofpulsesintegrated (postdetection) (a)10,000 10,000 1,000 lOa n=numberofpulses (bl_______ ~_ Pel=050 Pel=090 ~=0.99 102f---- a_-_-'---'-----l. 18---~--- ---------- 6f--------+-----------t-;>"'7"7"':~VL_---___+_------_l 41---------f-----,;~~.c:n~'f---------+_------____j12~------- ---------------------t----- . 
 Any use is subject to the Terms of Use as given at the website. Sea Clutter. 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15   blind folio 15.44 ch15.indd   44 12/15/07   6:17:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Each  ap,)licatior~ riiust be exatninccf individually to determine the best form of pulse compression to  use.  Other pulse-compression waveforms. Other pulse-compression methods include nonlinear  FM, discrete freque~icy-shift, polyphase codes, compound Barker codes, code sequencing,  conlplernentary codes, pulse burst, and stretch. 
 J. W.. and J. 
 current, as in Fig. 6.6c, is called  the pushing characteristic and the slope of the curve is the pushing figure. The lower the value  of the pushing figure, the better the frequency stability. 
 In summary, there are  two basic approaches to implementing digital pulse compression: time-domain and  frequency-domain convolution. A generic time-domain convolver consists of a com - plex FIR filter, where the coefficients are the complex conjugate of the transmitted  baseband waveform samples in time-reversed order (which is also the definition of  the matched filter for the transmitted signal). This architecture can compress any  arbitrary waveform. 
 PUT CAPABILITY OF A TRANSISTOR IS ITS BREAKDOWN VOLTAGE AND MAX IMUM CURRENT HANDLING  CAPABILITY 7ITHIN THAT LIMIT  THE MAXIMUM PRACTICAL LEVEL OF P OWER OUTPUT THAT CAN BE  OBTAINED FROM A SINGLE TRANSISTOR OVER A GIVEN BANDWIDTH IS GOVERNED BY THE THERMAL DISSIPATION LIMIT OF THE DEVICE !S DEVICES BECOME LARGER AND THE DISSIPATIVE HEAT FLUX FROM THE TOP SURFACE OF THE TRANSISTOR CHIP TO THE BOTTOM LAYER OF THE TRANSISTOR CHIP INCREASES  THE JUNCTION TEMPERATURE INCREASES TO THE POINT WHERE THE TRANSISTOR BECOMES THERMALLY LIMITED 2EGARDLESS OF THE SEMICONDUCTOR USED  THE ELECTRICAL PERFORMANCE AND OPERATING LIFETIME DEGRADE AT INCREASINGLY HIGHER TEMPERATURES 4HERE IS A COMPOSITE THERMAL TIME CONSTANT ASSOCIATED WITH THE NUMEROUS THERMALLY  RESISTIVE LAYERS BETWEEN THE TRANSISTOR JUNCTION AND THE HEAT SINK OR COLD PLATE TO WHICH THE DEVICE IS ATTACHED 4HIS OCCURS BECAUSE EACH LAYER SEMICONDUCTOR  CERAMIC SUB 
 7.9); the axes of the plane are the direction cosines cos ax, cos av. For any direction on the hemisphere the direction cosines are cos ax = sin 6 cos $ cos Ot3, = sin 6 sin c|> The direction of scan is indicated by the direction cosines cos axs, cos a^. Here the plane of scan is defined by the angle cj> measured counterclockwise from the cos OLx axis and is given by FIG. 
 Because the simulated  signal is predominately entering the radar through the sidelobes of the radar antenna— except when the radar main beam aligns with the simulator antenna—the synthesized  signal needs to be automatically adjusted in amplitude to compensate for the actual  sidelobe sensitivity in the direction of the simulator. Effectively, the synthesizer has to  amplify the transmitted signal according to the inverse of the amplitude of each pulse  received from the radar. The challenges in designing an affordable system include the  large dynamic ranges that have to be encompassed and the processing speed needed to  determine the characteristics of the transmitted signal. 
 IN TEST ")4  MANIFOLD !LSO  THE CALIBRATION PATH DOES NOT INCLUDE THE RADIATOR £Î°£xÊ *- 
 Gros, D. C. Sammons, and A. 
  ! &)'52%  !FTER -4) PROCESSING OF THE HARD 
 2.24  Other Detection Methods  ...................................  2.25  Predetection Integration  .....................................  2.25  2.5 System Noise Temperature  .................................... 
 When Eq. (20) issatisfied the power reflection coefficient isgiven by therelation +!azcoS2 ~ R2 = -. (21) (a’–1)’+4a2Cos’; Ifthebandwidth AXoftheabsorber bedefined astherange ofwavelengths inwhich more than half theincident power isabsorbed, itcan beshown from Eo. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 4.40  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 Most front-end  losses are applicable to both targets and clutter. 
 TO 
 Called the  Manastash Ridge Radar  (MRR ), it is designed to study turbulence in the iono - sphere, specifically auroral E-region irregularities, using range, doppler, and DOA  (via interferometry) measurements.2,48 Motivation for MRR development included  lower cost, increased safety, spectrum availability, and pedagogical opportunity.  MRR provides range-time intensity and range-doppler plots to the World Wide  Web every half-hour. Although it is not subject to the stringent air-defense require - ments for accurate location of multiple targets in real time, it has detected meteors  and aircraft in the course of normal operations. 
 As a result, a large PRF is required. As shown in Figure 2, the multi-angle SAR imaging system proposed in this paper uses three sets of receiving feeders and the digital T/R modules are divided into three groups, each with independent receiving feeder and phase shifter. The multi-beam data are separated in the time domain. 
 # 
 . IV. ON THE SCREEN  SHALL FIND ALL MANNER OF ANACHRONISMS IN  radar, and one of the most curious certainly  applies to the CRT, which we now know stands for  cathode-ray tube. 
 Sensors 2019 ,19, 2342. [ CrossRef ][PubMed ] 21. Malamou, A.; Pandis, C.; Karakasiliotis, A.; Stefaneas, P .; Kallitsis, E.; Daras, N.; Frangos, P . 
 There are two codes having this minimum peak sidelobe, one of which is 1610445 = 1 110 001 000 100 100 101. Computer searches are generally used to find optimal codes.25 However, the search time becomes excessively long as N increases, and recourse is often made to using other sequences which may not be optimal but possess desirable correlation characteristics. Maximal-Length Sequences. 
 NOISE SYNTHESIZERS  !IR 
 %ARTH DATA LINK IS SEVERELY LIMITED 7HILE IN BURST MODE  IT IS CUSTOMARY TO USE EACH BURST AS A SINGLE 
 02& WAVEFORM 4HE TRANSMIT DUTY CYCLE IS MAXIMIZED TO INCREASE DETECTION RANGE 4HE RECEIVER MAY BE RANGE GATED TO MATCH THE BANDWIDTH OF THE TRANSMIT WAVEFORM  BUT RANGE MEASUREMENT IS NOT ATTEMPTED ! 63 DWELL WILL CONSIST OF A SINGLE LOOK AT A GIVEN 02& 4HE COHERENT INTEGRATION  TIME IS MAXIMIZED WITHIN THE LIMITS OF THE MAXIMUM EXPECTED TARGET RADIAL ACCELERATION 63 IS OPTIMIZED FOR 3WERLING ) AND ))) TARGET AMPLITUDE FLUCTUATION STATISTICS AND THE CUMULATIVE PROBABILITY OF DETECTION OF INCOMING TARGETS OVER SEVERAL SEARCH FRAMES (IGH 
 Compensation-Pattern Selection . Selection of the compensation pattern  depends on the level of system performance required, the type of MTI filtering used, the  platform velocity, scan rate, and the characteristics required by normal radar parameters  such as resolution, distortion, gain, sidelobes, etc. For instance, an exponential pattern  and its corresponding difference pattern are excellent for single-delay-cancellation  DPCA but are unsatisfactory when double-delay cancellation is used. 
 20.13 Accuracy comparison in multipath. (a} Sum-delta monopulse bias error. Antenna height = 2 x aperture height; monopulse beams boresighted at H0 = 0.5; reflection coefficient = - 1. 
 LIKE SIGNALS FOR THE PURPOSE OF INTERFERING WITH  DISTURBING  EXPLOITING  DECEIVING  MASKING  OR OTHERWISE DEGRADING THE RECEPTION OF OTHER SIGNALS THAT ARE USED BY RADAR SYSTEMS n ! JAMMER IS ANY %#- DEVICE THAT  TRANSMITS A SIGNAL OF ANY DUTY CYCLE FOR THE SOLE OR PARTIAL PURPOSE OF JAMMING A RADAR SYSTEM n 2ADIO SIGNALS BY SPECIAL TRANSMITTERS INTENDED FOR INTERFERING WITH OR PRECLUDING THE  NORMAL OPERATION OF A VICTIM RADAR SYSTEM ARE CALLED  ACTIVE JAMMING 4HEY PRODUCE AT  THE INPUT OF A VICTIM SYSTEM A BACKGROUND THAT IMPEDES THE DETECTION AND RECOGNITION OF USEFUL SIGNALS AND DETERMINATION OF THEIR PARAMETERS 4HE MOST COMMON FORMS OF ACTIVE NOISE JAMMING ARE SPOT  SWEPT  AND BARRAGE NOISES 3POT NOISE IS USED WHEN THE CENTER FREQUENCY AND BANDWIDTH OF THE VICTIM SYSTEM TO BE JAMMED ARE KNOWN AND CONFINED TO A NARROW BAND (OWEVER  MANY RADARS ARE FREQUENCY 
 Gao, F.; Dong, J.; Li, B.; Xu, Q.; Xie, C. Change Detection from Synthetic Aperture Radar Images Based on Neighborhood-Based Ratio and Extreme Learning Machine. J. 
 Peterson, W. W., T. G. 
 However, Battan's text,10 revised in 1973, deserves special mention for its clarity and completeness and remains a standard for courses in radar meteorology that are taught in universities around the world. Doviak and Zrnic11 place special emphasis on doppler meteorological radar. Chapter 24 in the first "Radar Handbook," by Bean et al.,12 addresses the problem of weather ef- fects on radar. 
 atthegimbal axis parallel tothetiltaxis. Asynchro isalso located at theoutput crankshaft ofthetorque unit. The servoamplifier essentially amplifies the algebraic difference between the voltages from these take- offs, and thus actuates themotor inthetorque unit toassure alignment between theoutput shaft and thegyro. 
 Inaddition todescribing the paths taken byindividual electrons intheinteraction space, itishelpful toconsider thebehavior ofthespace l“IG. 1015.—Space charge inoscillating magnetron, charge asawhole. Intheabsence of~ffields, thespace charge forms a rotating cylindrical sheath around thecathode extending outabout half- ~vay totheanode (Fig. 
 250 INTRODUCTION TO RADAR SYSTEMS  When the particles are metallic spheres of radius a and sracing s between centers, the  dielectric constant of the artificial dielectric is approximately  t = 1 + 4nt s  assuming no interaction between the spheres.47 (7.20)  An artificial dielectric may also be constructed by using a solid dielectric material with a  controlled pattern of voids. This is a form of Babinet inverse of the more usual artificial  dielectric composed of particles imbedded in a low-dielectric-constant material.48 The voids  may be either spheres or cylinders, but the latter are easier to machine.  Lenses made from artificial dielectrics are generally of less weight than those from solid  dielectrics. 
 122–130, 1981. 69. W. 
 Eng ., vol. 1,   pp. 54–59, July 1963. 
 High track accuracy is needed for threatening targets or those that need a fire control TABLE 4.8  Three-slope FM Ranging Example There are two targets, A and B; FM slope = 24.28 MHz/s. Target A B Range (nmi) 10 20 Doppler frequency (kHz) 21 29 FM shift (kHz)  3  6 Observed Frequencies f0, no FM (kHz) 21 29 f1, FM up (kHz) 18 23 f2, FM down (kHz) 24 35 Possible sets that satisfy the relations shown in Eq. 4.12 and Eq. 
 In some nonradar applications, as for example radio astronomy, most of these  lossy components are not necessary as th'ey ate ·1n radar, so that a low noise figure front-end  can be used effectively. However, an extremely low receiver noise-figure is not usually warranted  in radar because of the unavoidable RF losses found in most radars. Even if the noise figure of  the receiver were essentially O dB, the overall receiver noise-figure would still be equal to the  losses in the RF portion of the system. 
 . 124 HOW RADAR WORKS  guided along such conducting tubes with negligible loss.  The energy does, of course, continue to travel along the  ‘pipeline’ of the guide in wave-form, just as it would,  according to one school of thought, travel in free space  by radiation. 
 India is the second largest consumer of space-based imaging radar data, used  for agriculture and forest management, and for measuring changes in its alpine gla - ciers. Countries such as Brazil graced with tropical forests rely on space-based radar  imagery to maintain surveillance and to compile annual statistics of deforestation.  Since radar imagery is a reliable method of mapping slicks on the ocean’s surface, it  is the principal means of monitoring oil spills that may result from a grounded tanker  or a vessel illegally pumping its bilges in a coastal area. 
 It consists of thousands of elements driven by transmit/receive (T/R) modules.  In the X-band radar, they will provide the full fire control sensor functions for the  Ground-Based Midcourse Defense system, including search, acquisition, tracking,  discrimination, and kill assessment. SPY-3. 
 800–809, 1991. 17. R. 
 Ships and other vehicles of war carried small trans-  mitter-receivers which, on being triggered off by detect-  ing ground stations, could automatically emit coded  pulses. These pulses show up at the ground station,  usually in addition to the echo received back; if the  coding is correct, then obvious indication is given that  the mobile outfit is carried by a ‘friendly.’  The network of beacons which came to be relied upon  in war may become an important adjunct to navigation  to-day, at sea and in the air. Earliest beacon signals  were presented to the navigator of the questioning craft  as fluctuating blips on his Type-A-displayed range-  scale, together with whatever indication of azimuth  (bearing) the apparatus might be capable of displaying. 
 VOLTAGE POWER SUPPLY  A LOW 
 At present, the theory of sea clutter does neither of these tasks very well and must be thought of as a book with the final chapters still to be written. Before discussing the current theories of sea clutter, it is important to distin- guish them from other so-called sea clutter models that are designed to provide a predictive capability. Some such models organize large quantities of empirical data by finding a multiple linear-regression formula relating the clutter cross sec- tion to a variety of parameters, such as grazing angle, wind speed, frequency, etc., all measured concurrently.1'40 Even a multiparameter matrix tabulation . 
 The first term of Eq. (16.2) for spectral width due to platform motion ap- proaches zero as the antenna points ahead. However the second term of Eq. 
 Asomewhat unusual fact isthat those electrons which are speeded uphave their radius ofcurvature reduced and return tothecathode, while those which areslowed down have their radius ofcurvature increased and move out toward theanode. Tomake this appear reasonable, letusconsider agreatly simplified case shown inFig. 10~12. 
 However, at the lower frequenci_es, the azimuth beamwidths are broader  and the available bandwidths are narrower than might be desired. Below UHF, the external  noise increases with decreasing frequency and can limit receiver sensitivity. The lobing of the  elevation pattern due to ground reflections results in wider elevation nulls at the lower  frequencies and can cause long fade times of the target signals. 
 However, when the transmitter is peak-power limited, it is  preferable to use a constant-amplitude transmitted signal and perform the weighting in the  receiver, in spite of the mismatched filter with its reduction in signal-to-noise ratio.25 In one  transmitting a linear-FM waveform with a gaussian envelope and a matched-filter  receiver to give -40 dB sidelobes resulted in 2.2 dB greater penalty in detection capability  than when a uniforni amplitude is transmitted with Hamming weighting on receive in a  niismatched filter.  It is possible to achieve low time-sidelobes with uniform-amplitude transmitted wave-  forrris and no theoretical loss in signal-to-noise ratio by means of nonlinear FM, as dis-  cussed later in this section.  Ilappler-tolerant waveforrn. 
 W. Wilson, “An update on the Nexrad program and future WSR- 88D support to operations,” Weather and Forecasting , vol. 13, pp. 
 Hyde: Studies of the Focal-Region of a Spherical Reflector: Geometric Op~ics,  IEEE Trans., vol. AP-16, pp. 317-324, May, 1968. 
          .   2!$!2 2%#%)6%23   È°ÎÇ &OR )& SAMPLING  A FREQUENCY AT LEAST TWICE THE )& BANDWIDTH IS  REQUIRED HOWEVER   OVERSAMPLING IS TYPICALLY EMPLOYED TO EASE ALIAS REJECTION FILTERING AND TO REDUCE THE  EFFECT OF !$ CONVERTER QUANTIZATION NOISE )& SAMPLING IS OFTEN PERFORMED WITH THE SIGNAL LOCATED IN THE SECOND .YQUIST REGION  AS SHOWN IN &IGURE  OR IN HIGHER .YQUIST REGIONS 3TATED 2ESOLUTION  4HE STATED RESOLUTION OF AN !$ CONVERTER IS THE NUMBER OF  OUTPUT DATA BITS PER SAMPLE 4HE FULL 
 265, pp. 524–-532, 1993. 101. 
 Potential effects of the ionosphere on space-based SAR imaging. IEEE T rans. Geosci. 
         !N EXAMPLE OF A &RANK #ODE MATRIX FOR -    IS GIVEN HERE  PP    § ©¨ ¨¨¨¶ ¸· ···           § ©¨ ¨¨¨¶ ¸· ···  CC C C     C CC C§ ©¨ ¨ ¨ ¨¶ ¸· · · ·  #ONCATENATING  THE ROWS OF THIS MATRIX YIELDS THE PHASE FOR EACH OF THE  SUBPULSES  &IGURE  SHOWS THE PHASE MODULATION CHARACTERISTIC OF THE &RANK #ODE FOR THE ABOVE  EXAMPLE .OTE HOW THE PHASE STEP BETWEEN SUBPULSES INCREASES BETWEEN SUBPULSE GROUPS WITH A LENGTH EQUAL TO FOUR 4HIS CHARACTERISTIC CAN BE REGARDED AS A STEPPED 
 TIME 
 Each module produces 2500 W peak and 50 W average for a 60-jjus pulse width at a 2 percent duty cycle. Drive power for the two banks of final output modules, 17.5 kW, is provided from the combined outputs of 12 more identical modules in the driver group. Predrivers and a redundant preamplifier are used as preceding drive stages. 
 Radio E11grs ..  vol. 22. 
 These techniques provide some advantages  in AGC or other processing techniques but at the cost of reduced SNR, reduced angle  data rate, and potential for cross coupling between azimuth and elevation information. A two-channel monopulse receiver18 combines the sum and difference signals  at RF, as shown in Figure 9.12. The microwave resolver is a mechanically rotated  RF coupling loop in cylindrical waveguide. 
 770-774, June, 1953.  50. Hall, W. 
 The Lucero equipment processed these through both antennas, providing both a range and a bearing estimate of the beacon from either of the dash or dot returns. The relative magnitude of the dash and dot returns also gave an indication of thedirection from which the beacon was being approached, with equi-signal power being received on the direct line of approach. There were two different aerial types used for Lucero, aerial aircraft type 301 and aerial aircraft type 184. 
 POWER DEVICES  4HEY ARE SUITABLE FOR STRIPLINE  MICROSTRIP  AND MONOLITHIC  CONFIGURATIONS 4HE MAIN DISADVANTAGE OF THE DIODE PHASE SHIFTER IS THAT AN ADDITIONAL SET OF DIODES IS NORMALLY REQUIRED FOR EACH ADDITIONAL BIT !S LOWER 
 Atthepropertime,theswitchisclosedandthestoredenergyisquickly discharged through theload,orRFtube,toformthepulse.Duringthedischarge partofthe cycle,thecharging impedance prevents energyfromthestorageelementfrombeingdissipated inthesource. Line-type modulator. Adelayline,orpulse-forming network (PFN),issometimes usedasthe storageelement sinceitcanproduce arectangular pulseandcanbeoperated byagas-tube switch.Thiscombination ofdelay-line storageelementandgas-tube switchiscalledaline-type modulator. 
 Thisfrequency was used because the team had acquired a tuned radio frequency receiver designed by EMI for their proposed television service, which operated at a frequency of 45 Mc/s and had a bandwidth o f 1 Mc/s. A suitable receiver could then be built but no small transmitter was available for airborne use. Therefore, in the autumn of 1936 a bistatic experiment was set up using a ground-based transmitter and the receiver in a Heyford bomber. 
 /1,  3PECIAL 
 Inpractice itisquite difficult torealize stabilization accuracies high enough tosatisfy theforegoing tolerances forthevarious types ofbeams and radars. This isprincipally due totheearly stage ofairborne stabili- zation development and the stringent weight requirements onairborne gyroscopes. Current developments should lead tomore highly accurate lightweight airborne antenna stabilization. 
 K.: " lonnsplicric Ri~dio Propagation," National Hurcair of St;tndards Monograpli 80.  Apr. 1. 
 BEAM NOISE JAMMING IS TO INCREASE THE  TRANSMITTER FREQUENCY AS AN ALTERNATIVE MEANS TO THE USE OF A LARGER ANTENNA  IN ORDER TO NARROW THE ANTENNAS BEAMWIDTH 4HIS RESTRICTS THE SECTOR THAT IS BLANKED BY MAIN 
 T. Bayliss, “Design of monopulse antenna difference patterns with low sidelobes,” Bell Syst.  Tech. 
 O'Shea, R. L.: "Radio Frequency Power/Divider Combiner Networks," U.S. Patent 4,583,061, Raytheon Company. 
 Here, we draw upon the work  of Billingsley.17 They collected data over a wide range of terrain and unlike most pre - vious near-grazing measurements, also collected extensive “ground-truth” information  and accurately calibrated their radars. Moreover, these data were over a wide range of  frequencies: VHF (167 MHz), UHF (435 MHz), L band (1.23 GHz), S band (3.24 GHz),  and X band (9.2 GHz). They had 43 different target areas in different parts of the U.S. 
 FORCE  SATELLITE LOCATION TECHNIQUE (OWEVER   BECAUSE OF THE LARGE APERTURE SIZES OR ARRAY LENGTHS  REQUIRED FOR SUFFICIENTLY ACCU 
 The output-stage CFA is usually preceded by a medium-power TWT that provides most of the chain gain. CFAs have also been used to boost the power output of previously existing radar systems. The dominant types of CFAs are all reentrant, distributed emission . 
 Figure 10.4  Curves of the same range (iso -range contours, circles) and relative velocity  (iso-Doppler conto urs, hyperbolas).     The iso- Doppler contours are the places for all objects of the same Doppler frequency if the  Radar is moving with the velocity v F at a height h of above the ground.  With a fixed place of  an object in the x- y plane, the iso- Doppler contour moves away with the flying Radar. 
 The treatment here will outline theconditions that must bemet, and then give illustrative examples oftwo quite different designs. HeatRemoval. ‘—The maximum safe ambient temperature formost ofthe r-f-head components—such ascomposition resistors, oiI-paper condensers, and blower motors—is about 85”C. 
 31, pp. 246–256, 1993. 48. 
 MON EXAMPLE OF THE CORPORATE 
 take the form of VHF and UHF fixed-beam systems, pointing vertically and at angles approximately 15° from the zenith. Such radars7 can make doppler measurements throughout the range of altitudes from a few hundred meters to 15 km above the surface, depending upon the wavelength selected and the power-aperture product available. Very powerful radars of this type are referred to as Mesosphere, Stratosphere, Troposphere (MST) radars because of their ability to make measurements throughout most of these atmospheric regions. 
 (ILL "OOK #OMPANY    * & 7HITE   3EMICONDUCTOR #ONTROL  .ORWOOD  -! !RTECH (OUSE    7 * )NCE  h2ECENT ADVANCES IN DIODE AND PHASE SHIFTER TECHNOLOGY FOR PHASED ARRAY RADARS v   PTS ) AND ))  -ICR  OWAVE *  VOL   NO   PP n  AND NO   PP n    * & 7HITE  h$IODE PHASE SHIFTERS FOR ARRAY ANTENNAS v  )%%% 4RANS  VOL -44 
 CWillumination hasbeenusedinmanysuccessful systems. Anexample istheHawktracking illuminator showninFig.3.3.Itisatracking radarasweltasan illuminator sinceitmustbeabletofollowthetargetasittravelsthrough space.Thedoppler. servo system  Narrow Irock- 1 kHz 30kHz  ing f~ller 3-  ~j+~]~XZZ-]~ ,  deteclor ornplif ier  Pedestol control  Figure 3.9 Block diagram of a CW tracking-ill~rninator.~~ (Corlrtesy IEEE.)  discrimination of a CW radar allows operation in the presence of clutter and.has been well  suited for low altitude niissile defense systems. 
 Processes Landforms 2015 ,40, 208–228. [ CrossRef ] 3. Luzi, G. 
 (ILL    PP n  4 - (ALL AND 7 7 3HRADER  h3TATISTICS OF CLUTTER RESIDUE IN -4) RADARS WITH )& LIMITING v IN  )%%% 2ADAR #ONFERENCE  "OSTON  -!    !PRIL   PP n  ' 'RASSO  h)MPROVEMENT FACTOR OF A NONLINEAR -4) IN POINT CLUTTER v  )%%% 4RANS  VOL !%3 
 Sci. 2018 ,8, 2443. [ CrossRef ] 16. 
 This property can be used as a possible basis for discriminating one target from another. For  example, a thin straight wire can be readily distinguished from a homogeneous sphere by  observing the variation of the echo signal amplitude as the polarization is rotated. The echo  from the sphere will be unmodulated, and the echo signal from the wire will vary between a  maximum and a minimum at twice the rate at which the polarization is rotated. 
 However, spurious IF frequencies of 0.34 (4H - 6L) and 0.4 (37/ - 4L) are generated at the extremes of the RF passband. Any extension of the instanta- neous RF bandwidth will produce overlapping IF frequencies, a condition that is not corrected by IF filtering. The 4H - 6L and 3// - 4L spurious frequencies, . 
 73. J. L. 
 GRAZING ANGLE (degrees) FIG. 13.5 Frequency dependence of sea clutter for wind speeds of about 15 kn: 5.3 GHz, Feindt;27 13.9 GHz, Schroeder;28 34.4 GHz, Masuko.29CROSS-POLARIZED RETURNS . line. 
 TO 
 Kroszcynski,J.J.: Pulse Compression by Means of Linear-Period Modulation. Proc. IEEE, vol. 
 !"  THAT CONSISTS OF AN  INDUCTIVE 
 As a result, this book will define  MTI radars as those radars whose PRF is sufficiently low enough to provide an unam - biguous range measurement, via pulse delay ranging, over the radar’s instrumented  range. The unambiguous range Ru is given by c/(2fR), where c is the speed of light  and fR is the PRF. Radars with PRFs that result in range ambiguities within the range  coverage of interest will be referred to as pulse doppler radars and will be the focus  of this chapter. 
 Maxwell’s equations may also be manipulated to generate a  pair of integral equations (known as the Stratton-Chu equations24):  E n H n E n Es ikZ dS = × + × ×∇ + ∇ ∫{ ( ) ( ) ( ) }0i Ψ Ψ Ψ  (14.5)  H nE n H n Es ikY dS = − × + × × ∇ + ∇ ∫{ ( ) ( ) ( ) }0 Ψ Ψ Ψi  (14.6) where n is the unit surface normal erected at the surface patch dS and ψ is the Green’s  function:  Ψ =e rikr/4π (14.7) ch14.indd   17 12/17/07   2:47:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 
 Binary codes that provide minimum peak time side- lobe levels but exceed the time sidelobe levels achieved by Barker codes (–20 log ( N)) are  termed minimum peak sidelobe codes.29 These codes are usually found using computer  search techniques. Skolnik28 and Levanon and Mozeson29 provide these codes for various  sequence lengths, along with the resulting time sidelobe levels. Complementary Sequences. 
 FUNCTION $ISPLAY0)  0ARALLEL )NDEX LINE.4 2ADAR   .EW 4ECHNOLOGY 2ADAR -ARINE TERM FOR COHERENT SOLID 
 MERCIAL AIRBORNE WEATHER AVOIDANCE AND OBSERVATION RADARS  AIRBORNE HURRICANE MONITORING PROVIDES DETAILED FORECASTS AND WARNINGS FOR APPROACHING COASTAL HURRICANES  !ND VERTI 
 AXIS THE DISTANCE Z IS ALSO GIVEN BY   ZX XZII 
 Atthereceiving station, thereceiver amplifies and demodu- lates theincoming signals and delivers theresults toan“analyzer.” The latter performs thenecessary sorting into video signals, trigger pulse, and scanner data. The video and trigger are delivered immediately tothe indicator system. The scanner data must usually bemodified inform before being passed oneither totheindicators fordirect useinelectrical display synthesis, ortothe “scan converter.” The scan converter uses these data toconstruct aduplicate ofthe scanner motion that can be used todrive aposition-data transmitter associated with theindicators. 
 Modern electronic timing and display techniques have been developed tosuch apoint that this can readily be done. One ofthesimplest ways inwhich radar echo signals can bedisplayed isshown inFig. 1.3. 
 This can be found by comparing the SNR values  required to achieve a specified PD value for the radar system with and without the SLB.  L is a function of many parameters such as PD, PFA, F, GA, JNR, and b. A numerical  evaluation of these performance parameters can be found in the literature (specifically  Chapter 3 of Farina,34among others42–50). 
 In order to verify the feasibility and reliability of the model and the parameter estimation algorithm, a simulated experiment was designed to obtain the RMSE of four unknown parameters in the model (viscosity, elasticity modulus, linear velocity, and height correction). In the real data experiment, a stretch of highway in Fuoshan, Guangdong province was selected as the test area. The SBAS algorithm was used to process 16 TerraSAR X high-resolution images. 
 18. Conical scan requires only a single channel and extracts the angle information which is contained in the amplitude and phase of the scan amplitude modulation by simple envelope detection. Conventional monopulse normally requires three complete channels, which must track in gain and phase to maintain the proper relationship between the sum and difference channel signals (the angle informa- tion is contained in the difference/sum ratio).15 The complexity of monopulse, however, provides well-known performance advantages over conical scan. 
 Modern  pulse doppler radars have migrated to the use of active electronically scanned arrays  (AESAs).20 AESAs contain transmit/receive (T/R) modules, each comprising a trans - mit power amplifier and a receive low-noise amplifier (LNA) along with an attenuator  and phase shifter, at each antenna element. If the same antenna is used for transmit and receive, a duplexer must be included.  This duplexer is usually a passive device, such as a circulator, which effectively  switches the antenna between the transmitter and receiver. 
 DENT ON THE PINCH 
 Keywords: synthetic aperture radar (SAR); inverse synthetic aperture radar (ISAR); moving ship; refocusing; fast minimum entropy 1. Introduction Synthetic aperture radar (SAR) is widely employed in military surveillance, geography mapping and resource surveying. High-resolution SAR image is of great signiﬁcance for homeland and military security [ 1–4]. 
 For volumetric clutter, such as chaff or rain, the average cross section is  σ ητη = ⋅ = ⋅ ⋅ ⋅ ⋅⋅⋅ V R Hc cq qaz el2 (2.18) where Vc is the volume of clutter illuminated (m3) and h is the clutter reflectivity factor  (m2/m3). The volume Vc is computed from the height extent of clutter H (meters), the  azimuth extent of the clutter R⋅qaz, and the radar range resolution cell t. If the clutter  completely fills the vertical beam, then H R= ⋅qel, where qel is the elevation beam - width. 
 ' Transmitted waveform andtheambiguity function. Theparticular waveform transmitted bya radarischosento·satisfytherequirements for(1)detection, (2)measurement accuracy, (3)resolution, (4)ambiguity, and(5)clutterrejection. Theambiguity function anditsplot,the. 
 E., and M. Bernfeld: "Radar Signals," Academic Press, New York, 1967.  25. 
 DISPLAY SYNTHESIS Displays are synthesized bycombining the components and tech- niques described inthepreceding sections ofthis chapter. Although space will permit only brief descriptions ofsome ofthe more important and ~haracteristic ofthe methods used, variations tofitparticular circum- stances and extensions toother applications will beapparent inmany cases. 13.13. 
 Thermal noise (generally internal when the  radar is a SAR) is often referred to as additive noise , since it adds to the scene inde - pendent of the scene content. Another type of unwanted background in a SAR image  ch17.indd   17 12/17/07   6:49:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 PULSE CANCELER  ASSUMING A LARGE NUMBER OF PULSES )F QUADRATURE -4) CHANNELS SEE 3ECTION   ARE NOT EMPLOYED  THERE IS AN ADDITIONAL LOSS OF   TO  D" 4HE ABSCISSA OF THESE CURVES   66 "  REPRESENTS THE RATIO OF TARGET VELOCITY  6 TO THE  BLIND SPEED  6"   K FR   WHERE  K  IS THE RADAR WAVELENGTH AND  FR IS THE AVERAGE 02& OF  THE RADAR 4HE ABSCISSA CAN ALSO BE INTERPRETED AS THE RATIO OF THE TARGET DOPPLER FRE 
 MINED RATES IN ORDER TO IMPROVE THE CUMULATIVE PROBABILITY OF AIRCRAFT SURVIVAL  ! TOWED DECOY IS A SMALL AERODYNAMICALLY STABLE BODY THAT HOUSES A MINIATURE JAM 
 The receiver noise ﬁgure and microwave losses are unknown but may well have been relatively poor in the early prototype systems. An important bene ﬁt of operating in X-band in ASV Mk. VII would have been the improved ability to resolve targets closely spaced in azimuth and the improved bearing accuracy when identifying land features or homing onto a target. 
 PER 
 It is  for these reasons that different design groups, in meeting the same user's reqi~irements, often  produce different radar designs that bear little oi~tward resemblance to one anotiler, yet  accomplish the same objectives.  536INTRODUCTION TORADAR SYSTEMS A..figureofmerit"thathasbeenusedinthepastforcomparison ofOTHradarsisthe DBJvaluewhichisdefined astheproductofPayG,G,Tc,expressed indB.Theunitsarejoules (energy), ordBrelativetoajoule,hence thenameDB1.Itisquitedifferent thanthemeasure of performance givenabove.Thisfigureofmeritismorerepresentative ofa..searchlighting " radarandnotasurveillance radar. Ground-wave OTHradar.ThetypeofOTHradardescribed intheabovethatpropagates via refraction fromtheionosphere issometimes calledasky-wave radar.Itisalsopossible atHF topropagate energyaroundthecurvature oftheearthbydiffraction. 
 94 HOW RADAR WORKS  it can produce oscillation (when it is more usually known  as a ‘Numans oscillator’), and with different values it  can be made to have a stable and an unstable state, the  change from the stable to the unstable being produced  by a positive-going pulse.  G3 =  Input G2 [777 ee paceman Gi = = oe oF  FIG. 13  In this circuit (Fig. 
 Less range  eclipsing than in high-PRF.Sidelobe clutter can limit  performance. Ambiguity  resolution required. Low antenna  sidelobes necessary. 
 that would tend to favor the higher frequencies in many  applications. The lower the frequency, the more difficult it is to direct the radar energy at low  angles. This is illustrated in Sec. 
 In the VHS case, for instance, with a 70-degree squint angle [ 26], the less accurate DPEC methods will lead to serious image quality degradation. Aiming at implementing accurate enough DPEC for the VHS airborne SAR imaging, we propose an extended MAM (EMAM) method, as shown in Figure 2b. Compared with the IMAM method, the EMAM method realizes higher accuracy by further estimating and compensating the second-order component of the spatially-dependent Doppler rate and the ﬁrst-order component of the spatially-dependent derivative of the Doppler rate. 
 This configuration allows beams to be formed in any direction, and multiple beams can  be formed simultaneously, if desired, by using the same sample data and implementing  different time delays to form the different beams. However, at this writing, putting a  digital receiver behind every element is expensive and is usually not feasible for most  large antenna applications (i.e., for systems with thousands of elements). One compro - mise solution is shown in Figure 25.21 c, where analog beamforming is used to imple - ment subarrays, which are followed by digital receivers and digital time delays. 
 Using the radar equation, the received signal level can be  calculated to determine if sufficien t power exists to detect a  reflected  radar pulse. Combining multiple pulses to  accumulate greater signal p ower and average out the noise i s  also helpful for increasing the detection range.   Pulse Width   Pulse width is an important property of radar signal s. 
 Wilson: Track Initiation in a Dense Detection Environment, Naval Researcl~  Lahorntory (Washington, D.C.) Rept 8238. July 28. 1978. 
 A Frequency-Domain Imaging Algorithm for Highly Squinted SAR Mounted on Maneuvering Platforms With Nonlinear Trajectory. IEEE T rans. Geosci. 
 Ifallinformation needed forthe desired use can beobtained with beacon signals alone, itisnotnecessary tohave aproper radar setatall, and the radar set can then bereplaced byaninterrogator-responsor. This has atransmitter and receiver like those ofaradar set, but itisin general somewhat smaller and lighter since not somuch transmitted power isrequired fortriggering beacons asisrequired forgetting adequate radar echoes. Such equipments can beespecially economical insize and weight ifrange only is\\-anted, orifthe sort ofazimuth information obtainable bylobe-s~vitching isadequate. 
 Parkins and R. K. Moore, “Omnidirectional scattering of acoustic waves from rough sur - faces of known statistics,” J. 
 Inconsequence, greater energy perplllse can safely beobtained forthelonger pulses. Pulse durations greater than 5psec arerarely employed when magne- trons areused astransmitter tubes. Frequency modulation during the pulse becomes aserious problem for longer pulses, even ifsparking troubles areovercome. 
 Details of the Seasat-A antenna are discussed in Sec. 22.4. The solid- state radar transmitter generated a nominal peak power of 800 W with a linear frequency modulation (LFM) derived from a stable local oscillator (stalo). 
 Now it will be recalled from our knowledge of wave propagation that there is an essential difference between  _ What may be termed earth and non-earth waves; there is also attenuation of the indirect-ray component of the  . THE ECHO COMES HOME 53  electromagnetic wave propagation, for the earth’s atmo-  sphere is by no means a constant dielectric. Radio  ‘waves are attenuated much less in the air than in the  earth’s surface, and the upper limit is set by the density  of free electrons in the ionosphere. 
 February. 1978. See also same title and author in IEEE EASCON '76  Record, pp. 
 There is also a backscattering contribution ftom a" creeping  0  er =0.4 >..2  §  li; -201---1-~~~~~~~-+~~~~~~~~~~~  er = 0.01 X2  V>  l  ~ -.30-­e  u  Oiomefer (Wovefengths)  Figure 2.11 Radar cross section of a cone sphere with 15° half angle as a function of the diameter in  wavelengths. (After Blore,21 IEEE Trans.) · . 180°  2700 90° (al  160°  90° (b)  Figure 2.12 Measured radar cross section (u/A2 given in dB) of a large cone-sphere with 12.5° half angle  and radius of base= 10.4A. 
 SCALE MODEL FOR ( 
 E. D. Kaplan, Understanding GPS, Principles and Applications , Norwood, MA: Artech  House, 1996. 
 GRAPHIC REGIONS 4HERE ARE TWO BENEFITS TO UNDERSTANDING SOIL PROPERTIES IN RELATION TO '02 4HE FIRST  IS TO UNDERSTAND THE APPLICABILITY OF '02 TO PARTICULAR SOILS AND HENCE THE POSSIBILITY OF USING '02 TO DETECT BURIED TARGETS SUCH AS PIPE  CABLES  LANDMINES  ETC 4HE SECOND IS TO USE '02 TO CHARACTERIZE SOILS AND SOIL PROPERTIES '02 CAN PROVIDE A DETAILED MAP OF THE SUBSURFACE  WHICH WHEN COMBINED WITH  TRADITIONAL SOIL SURVEY METHODS CAN PROVIDE INFORMATION ON THE TYPE OF SOIL  ITS EXTENT LATERALLY AND IN DEPTH  THE WATER TABLE  THE LAYERING AND FEATURES OF THE SOIL  AND HENCE ITS LOCAL GEOLOGY AND HISTORY '02 HAS BEEN USED IN THE 53 BY THE $EPARTMENT OF !GRICULTURE 
 A d-c electric fielcl is applied t~ctwccii tl~c :triode  (slow-wave structure) and the cathode. A magnetic field is perpendicular to the plane of the  Ilapcr. ?-lie electrolls emitted frorri tlle catliode. 
 OFF VOLTAGE IS THE VOLTAGE THAT WHEN APPLIED TO THE GATE TERMINAL CAUSES THE CURRENT IN THE TRAN 
 It is the  most obvious of the various types of echo signal modulation by a complex-shaped  target and is readily visualized as the fluctuating sum of many small vectors changing  randomly in relative phase. Although it is called noise , it may include periodic compo - nents. Amplitude noise typically falls into a low frequency and high frequency region  of interest. 
 This new degree of accuracy is such that  the geodetic surveys of the past cannot provide maps of:  sufficient reliability, and for the first time in history  our navigational methods are really ahead of our existing  maps.  The essence of the new methods is this: if two radar  transmitters send out truly synchronized pulses—that is  to say, the pulses of energy leave the aerials at the same  instant of time—then a receiver situated anywhere on  the perpendicular bisector of the straight line joming  the two transmitters will receive the two pulses simul-  ‘taneously, because any point in this bisector is equi-  distant from both transmitters.  At any other point there will be a time difference in  the receipt of the pulses, because the receiver will then  be nearer one transmitter than the other, so, of course,  ‘the pulses from one transmitter will reach there earlier,  by a very minute fraction of time. 
 LOOP METHODS ARE  CHEAPER AND SIMPLER TO IMPLEMENT THAN DIRECT 
 The analysis isvery easy inthecase ofajut,perfectly rejecting, surface. Let usconsider anondirective transmitting antenna Alocated ata height h,above aflat reflecting surface S,asinFig. 2.9. 
 Each such signal triggers thetransmitter inthe beacon and causes itto radiate one ormore pulses cfradio energy that may have almost any desired power, frequency, duration, number, and characteristic spacing. Figure 8.1gives ablock diagram ofabeacon. Since ittakes time forthe beacon toreact, thefirst reply pulse comes back totheradar setslightly delayed and indicates arange slightly greater than the true one. 
 178-184, March,1974. 3.Mallinckrodt, A.J.,andT.E.Sollenberger: Optimum Pulse-Time Determination, IRETrans.,no. PGIT-3, pp.151-159, March,1954. 
 Scanning and Target Properties. In addition to the spectral spreading caused by transmitter noise and by microphonism, there is a spreading of the CW energy by the target and by the scanning of the antenna. Generally, the spreading by even a rapidly scintillating aircraft target does not produce appreciable energy outside a normal .doppler frequency bandwidth. 
 1048–1058, 1979. 115. I. 
 !RRAY 3YSTEMS AND 4ECHNOLOGY    "OSTON 53!   /CTOBER n    PP n  - #ICOLANI  ! &ARINA  % 'IACCARI  & -ADIA  2 2ONCONI  AND 3 3ABATINI  h3OME PHASED 
 However, if the time of observation is too long, the  doppler frequency of a point P on the rotating target will not be constant and the doppler  spectrum wpt broaden with a consequent reduction in resolution. That is, there is ~n apparent  target acceleration which limits the resolution. The result is that there will be an optimum time  of ohservation, or aspect angle change, when attempting to image a target with the inverse  SAR technique.101  14.2 HF OVER-THE-HORIZON RADAR20  Frequencies at VHF or lower are seldom used for conventional radar applications because of  their narrow bandwidths, wide beamwidths, high ambient noise levels, and the potential  interference from other users of the crowded electromagnetic spectrum. 
 In this very simple case, the operation carried out by the decomposition becomes clear:/bracketleftBig /vectorx1/vectorx2/bracketrightBig ·/bracketleftBigg cs −sc/bracketrightBigg =/bracketleftBig /vectore1/vectore2/bracketrightBig (5) The Ematrix is thus obtained as a simple linear combination of columns of X.Vis the Gibbs rotation matrix and: |c|2+|s|2=1 (6) In a geometrical representation we can consider cand sparameters able to scale, rotate and phase shift vectors they multiply so that their sum and difference mixtures give the two orthogonal vectors inE. The modula of such vectors represent the singular values; it is easy to demonstrate that they are proportional to the estimates of the standard deviations of the resulting signals in E. When applied to a multicolumn matrix, this procedure tends to accumulate all the strongly correlated information on columns in the ﬁrst left singular vector. 
 Prengaman: Integration and Automation of Multiple Co-located Radars,  lncernatimwl Conference RADAR-77. Oct. 25-28. 
  /CTOBER   PP  
 In one airborne monopulse radar  antenna23 using the polarization twisting technique, good performance was obtained over a 12  percent bandwidth. The subreflector was supported by a transparent (dielectric) cone, with  resistive-card absorbers embedded in the support cone and oriented so as to reduce the  cross-polarized wide-angle radiation by rn&e than 20 dB.  3. 
 Cooley and Daniel Davis12.1 12.1  Introduction / 12.7 12.2  Basic Principles and Parameters / 12.3 12.3  Reflector Antenna Architectures / 12.16 12.4  Reflector Feeds / 12.25 12.5  Reflector Antenna Analysis / 12.37 12.6  Mechanical Design Considerations / 12.35   Acknowledgments / 12.47 Chapter 13 Phased Array Radar Antennas Joe Frank and John D. Richards13.1 13.1  Introduction / 13.7 13.2  Array Theory / 13.9 13.3  Planar Arrays and Beam Steering / 13.15 13.4  Aperture Matching and Mutual Coupling / 13.20 13.5  Low-sidelobe Phased Arrays / 13.28 13.6  Quantization Effects / 13.34 13.7  Bandwidth of Phased Arrays / 13.38 13.8  Feed Networks (Beamformers) / 13.46 13.9  Phase Shifters / 13.57 13.10  Solid-state Modules / 13.53 13.11  Multiple Simultaneous Receive Beams / 13.54 13.12  Digital Beamforming / 13.56 13.13  Radiation Pattern Nulling / 13.57 13.14  Calibration of Active Phased Array Antennas / 13.60 13.15  Phased Array Systems / 13.62 Chapter 14 Radar Cross Section Eugene F. Knott14.1 14.1  Introduction / 14.1. 
 PASS SPACE 
 Cost is a major factor in provid - ing high-precision-tracking capability. Therefore, it is important to know how much  error can be tolerated, which sources of error affect the application, and what is the  most cost-effective means to satisfy the accuracy requirements. Because tracking radars track targets not only in angle but also in range and some - times in doppler, the errors in each of these target parameters must be considered on  most error budgets. 
   PP n   3EPTEMBER   , ! 7AINSTEIN AND 9 $ :UBAKOV   %XTRACTION OF 3IGNALS &ROM .OISE  .EW 9ORK $OVER    * #APON  h/PTIMUM WEIGHTING FUNCTIONS FOR THE DETECTION OF SAMPLED SIGNALS IN NOISE v  )2%  4RANS )NFORMATION 4HEORY  VOL )4 
 414 INTRODUCTION TO RADAR SYSTEMS  The ambiguity diagram in three dimensions may be likened to a box of sand. The total  amount of sand in the box is fixed and corresponds to a fixed signal energy. No sand can be  added, and none can be removed. 
 The modeled target is a cylinder with a radius of 3.5 cm and  a height of 5 cm. It is shallowly buried at about 2.5 cm below the air-ground interface.  FIGURE 21.10  Simulation of A-scan using 300 MHz center frequency ( Courtesy IEE )1 0.5 −0.5 −1−10 40 60 80 100 120 tA-scan simulation 140 160 180 2001 FIGURE 21.11  Simulation of A-scan using 500 MHz center frequency ( Courtesy IEE )1 0.5 −0.5 −1−10 40 60 80 100 120 tA-scan simulation Equiv alent timeAmplitude 140 160 180 2001 ch21.indd   16 12/17/07   2:51:25 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 PROPA 
 43-46,May,1977. 49.Ratliff,P.C,W.Cherry, M.J.Gawronski, andH.Goldie: L-Band ReceIver Protection, Microwave J.•vol.19,pp.57-60,January, 1976. 50.Goldie,H.:What'sNewWithReceiver Protectors?, Microwaves, vol.IS,pp.44-52,January, 1976. 
 ANGLE DIAGNOSTICS IS PERFORMED  WHICH TESTS THE INTEGRITY OF THE ENTIRE MEASUREMENT  PROCESSING  AND FLIGHT CONTROL CHAIN OFTEN ENOUGH TO KEEP THE PROBABILITY OF A FAILURE 
 As is evident, a discrete return in the sidelobes is . FIG. 17.8 Two-channel sidelobe blanker.DETECTION LOGIC DET.MGRGM NO NONO NO YES YES NOYESO1 O1 O1 O1O O11 OO11OOOO 1 11 1 DETECTIONSOUT 0=^>NO DETECT; 1 =^> DETECTMGRMAIN CHANNELCFAR MAIN CHANNELDETECTION THRESHOLD MAIN-TO-GUARD RATIO THRESHOLD GUARD CHANNEL DETECTIONTHRESHOLD GUARDCHANNEL CFARPOSTDETECTION INTEGRATION POSTDETECTIONINTEGRATIONLINEAR DETECTOR LINEAR DETECTORDOPPLERFILTER BANK DOPPLER FILTER BANKA/DCONVERTER A/D CONVERTERMAIN CHANNELRECEIVER GUARD CHANNEL RECEIVERMAINCHANNELANTENNA GUARDCHANNEL ANTENNA . 
 Although added delay lines reduce the clutter, they also reduce the  number of moving targets detected because of the narrowing of the passband. For example, if  the -10 dB response of the filter characteristic is taken as the threshold for detection and if  the targets are distributed uniformly across the doppler frequency band, 20 percent of all  targets will be rejected by a two-pulse canceler (single delay-line canceler), 38 percent will be  rejected by a three-pulse canceler (double canceler), and 48 percent by a four-pulse canceler  (triple canceler). These filters might be "optimum" in that they satisfy the specified criterion,  but the criterion might not be the best for satisfying MTI requirements. 
 PULSE BANDPASS SIGNAL  DEFINED AS   XT    ! RECT T4  COS ;O  F  T   O@ T=    WHERE 4 IS THE PULSEWIDTH    F IS THE CARRIER FREQUENCY   @  IS THE ,&- SLOPE  AND THE RECT  FUNCTION IS DEFINED AS   RECT  XX X    ª «­ ¬­  \\   \\     4HE ,&- SLOPE IS GIVEN BY  @   o "4  WHERE THE PLUS SIGN APPLIES FOR A POSITIVE  ,&- SLOPE TERMED AN  UP 
 Nengjing and Z. Yi-Ting, “A survey of radar ECM-ECCM,” IEEE Trans ., vol. AES–31, no. 
 Leuschen, T. Atkins, J. Legarsky, P. 
 IMPULSE 
 390 TIfJY MAGNETRON AND THE PULSER [SEC. 10.11 25kwtothemagnetron, atpulse durations of0.8psec and 2.2~sec. The components weigh approximately 6lb. 
 ABLE 4HE MIXER ITSELF AND THE PRECEDING CIRCUITS ARE GENERALLY RELATIVELY BROADBAND 4UNING OF THE RECEIVER  BETWEEN THE LIMITS SET BY THE PRESELECTOR OR MIXER BANDWIDTH  IS ACCOMPLISHED BY CHANGING THE ,/ FREQUENCY /CCASIONALLY  RECEIVERS WILL INCLUDE FILTERING BEFORE THE ,.! IN ORDER TO LIMIT THE EFFECTS OF INTERMODULATION DISTORTION THAT CAN OCCUR IN THE ,.! %VEN WHEN FILTERING IS INCLUDED BEFORE THE ,.!  A SECOND FILTER IS OFTEN STILL REQUIRED BETWEEN THE ,.! AND THE MIXER IN ORDER TO REJECT THE AMPLIFIER NOISE AT THE IMAGE FREQUENCY 7ITHOUT THIS FILTER  THE NOISE CONTRIBUTION OF A BROADBAND ,.! WOULD BE DOUBLED. 
 SAMPLING OF THE SIGNAL FOLLOWED BY FILTERING AND DECIMATION PROVIDES AN IMPROVEMENT OF ONE HALF 
 Manasse, R.: Range and Velocity Accuracy from Radar Measurements, unpublished internal report  dated February,' 1955, MIT Lincoln Laboratory, Lexington, Mass. (Not generally available.)  9. Slepian, D.: Estimation of Signal Parameters in the Presence of Noise, IRE Tram., no. 
 Meteorol. Soc. ,  Albuquerque, 2001. 
 Effect of Slant Range on Doppler Offset.  The antenna boresight velocity VB is  the ground-velocity component along the antenna centerline (boresight) and is given  as (– Vg cos a 0). If the clutter surface were coplanar with the aircraft, this component  would be equal to ( −Vg cos y0) and would be independent of range. 
 PLANE ANGLE IN XY PLANE            . 
 Pulsed techniques were developed from the 1930s  onward as a means of probing to considerable depths in ice (Steenson2 and Evans3);  in fresh water and salt deposits (Unterberger4); in desert sand and rock formations  (Kadaba5 and Morey6). Probing of rock and coal was also investigated by Cook7,8 as  well as Roe,9 although the higher attenuation in the latter material meant that depths  greater than a few meters were impractical. Nilsson10 gives a more extended account  of the history of GPR and its growth up to the mid-1970s. 
 INTERVAL RATIO WOULD PROBABLY BE CHOSEN FOR A PRACTICAL SYSTEM /NCE %Q  FOR THE LIMITATION ON  ) DUE TO SCANNING AND STAGGERING IS OBTAINED   IT IS POSSIBLE TO DETERMINE THE LIMITATION ON  ) DUE TO INTERNAL 
 Carrara, W.; Goodman, R.; Majewski, R. Spotlight Synthetic Aperture Radar: Signal Processing Algorithms ; Artech House: Norwood, MA, USA, 1995. 23. 
 FREQUENCY SIGNAL COMPONENT  PRODUCING THE COMPLEX BASEBAND SIGNAL SHOWN ON LINE  4HIS SIGNAL  WHICH NOW HAS A TWO 
 We may complete our classification ofpossible radar types byspecifying what use the receiver makes ofthis information. For example, inaradar ofthe usual pulse type, the linear phase change ingoing from com- ponent tocomponent ofthe returned waves may bejust compensated byanincreased time. Asaresult, thereturned waves add toamaximum atatime later than dothose intheoutgoing spectrum. 
 RELIABILITY POWER AMPLIFIER APPLICATIONS 4HE UNDERSIDE OF THE ,$-/3 TRANSISTOR DICE IS THE SOURCE CONNECTION THUS  THE CHIP   CAN BE MOUNTED DIRECTLY TO A METAL PACKAGE BASE 4HIS IS UNLIKE THE 3I "*4 WHERE THE HIGH VOLTAGE COLLECTOR CONTACT IS THE UNDERSIDE OF THE CHIP !S A RESULT OF NOT HAVING TO ELECTRICALLY ISOLATE THE UNDERSIDE OF THE ,$-/3 CHIP  THERE IS  NO NEED TO USE THE POTEN 
 FORMS AT AN )& FREQUENCY PRIOR TO UPCONVERSION TO THE 2& OUTPUT FREQUENCY &ILTERING IN THE EXCITER IS REQUIRED TO REJECT ALIASED SIGNALS FROM THE DIRECT DIGITAL SYNTHESIZER AND UNWANTED MIXER PRODUCTS 2& GAIN IS TYPICALLY REQUIRED TO PROVIDE A SUFFICIENT DRIVE LEVEL TO THE TRANSMITTER OR PHASED ARRAY ANTENNA !LMOST ALL MODERN RADAR SYSTEMS USE DIGITAL SIGNAL PROCESSING TO PERFORM A VARIETY  OF FUNCTIONS  INCLUDING PULSE COMPRESSION AND THE DISCRIMINATION OF DESIRED TARGETS FROM INTERFERENCE ON THE BASIS  OF VELOCITY OR THE CHANGE IN PHASE FROM ONE PULSE TO THE NEXT  0REVIOUSLY  PULSE COMPRESSION WAS PERFORMED USING ANALOG PROCESSING WITH DISPERSIVE DELAY LINES  TYPICALLY SURFACE ACOUSTIC 
 1.2 applies. However. the  beatnwidtli rather tliari the antenna gain is usually measured at laser frequencies so that  (;, = nZ/Oi [nay be silbstitrlted into the radar equation. 
 bf=1t'tB(2EIN O)1/2triangular pulse Thermsfrequency errorforagaussian-shaped pulseis(11.32) (11.33) gaussian pulse1.18 B bf=nr{2EINo)1/2,=1.18(2EIN o)1/2 Thetime-delay andfrequency-error expressions obtained inthissectionapplyforasingle observation. Whenmorethanoneindependent measurement ismade,theresultant errormay befoundbycombining theerrorsintheusualmanner forgaussian statistics; thatis,the variance (squareoftJforbTR)ofthecombined observations isequaltoIINofthevariance ofa singleobservation, whereNisthenumberofindependent observations. Ifp2ora2remains the sameforeachmeasurement, theexpressions derivedherestillapply,butwithEthetotalsignal energyinvolved inallNobservations. 
   VOL     PP n  * &RANK  h"ANDWIDTH CRITERIA FOR PHASED ARRAY ANTENNAS v IN  0HASED !RRAY !NTENNAS  ! ! /LINER  AND ' ( +NITTEL  .ORWOOD  -! !RTECH (OUSE    PP n  7 " !DAMS  h0HASED ARRAY RADAR PERFORMANCE WITH WIDEBAND SIGNALS v  !%3 #ONV 2EC   .OVEMBER   PP n  # " 3HARP AND 2 " #RANE  h/PTIMIZATION OF LINEAR ARRAYS FOR BROADBAND SIGNALS v  )%%% 4RANS   VOL !0 
 Binder, “Foliage penetration data collections and investiga - tions utilizing the P-3 UWB SAR”, Proceedings SPIE , vol. 2757, p. 136–144, 1999. 
 TER AND TAIL ASPECT TARGETS IN LEAD PURSUIT ENGAGEMENTS AN ATTACK GEOMETRY WHERE THE NOSE OF THE ATTACKING AIRCRAFT IS POINTED AHEAD OF THE TARGETS PRESENT POSITION  -273 PROVIDES COMPLETE SITUATIONAL AWARENESS PERCEPTION OF THE SURROUNDING TACTICAL ENVI 
 I. Skolnik (ed.), McGraw-  Hill Book Co., New York, 1970.  58. 
 ,/ ÊÊ , 
 LEADED  LOW 
 This video amplification isdifficult because ofthe bipolarity and wide dynamic range ofthe signals. Unless special precautions are taken, strong signals from moving targets may draw grid current and bias the amplifier tothepoint where weaker moving-target signals arelost. The bipolar nature ofthe signals prevents the application ofthe clamping technique, which isuseful inavoiding asimilar trouble with unipolar video amplifiers. 
 38. Nicholls, L. A.: Reduction of Radar Glint for Complex Targets by Use of Frequency Agility, IEEE  Tmtu., vol. 
 K. C. M.: A Low Noise CW Doppler Technique, Natl. 
 H. Knittel (eds.), Artech House, Inc., Dedham; Mass., 1972, pp. 212-218. 
 At a range of 10 nmi, the clutter-limited performance would have been worse by 10.6 dB, 12 dB, 7.7 dB,3.7 dB and 3.2 dB, in sea states 1 –5, respectively. A conventional method of modelling performance is to assume that the radar is able to control false alarms at a constant level at all ranges. Modern radars achievethis with advanced signal processing but on these early radars the false alarm rate for clutter and noise could only be controlled with the radar gain control and the display brightness. 
 TION LOSS IN THE CASE OF DIODE PHASE SHIFTERS  AND FOR MINIMAL COST /N THE OTHER HAND  A LARGE NUMBER OF BITS IS REQUIRED FOR BEST PERFORMANCE IN TERMS OF GAIN  SIDELOBES  AND BEAM 
 W. Haydon, and D. L. 
 LEVEL ESTIMATES v 2#! 2EV  VOL   PP n  3EPTEMBER   2 , -ITCHELL AND * & 7ALKER  h2ECURSIVE METHODS FOR COMPUTING DETECTION PROBABILITIES v  )%%%  4RANS  VOL !%3 
 The ESA series  of satellites use midday sun-synchronous orbits because their payloads include optical  sensors. The resulting half-orbit eclipse contributes to their per-orbit SAR operational  limit of ten minutes. J-ERS-1. 
 Plrbl. no. 155. 
 The Frank polyphase codes32 derive the  sequence of phases for the subpulses by using a matrix technique as follows:  0 0 0 0 0 1 2 1 0 2 4 2 1 0 1 2 1      ( ) ( ) ( ) ( ) (M M M M− − − − M M−          12) (8.17)FIGURE   8. 18 Histogram of peak time sidelobe levels for 15-bit sequences: ( a) all possible 15-bit  sequences and ( b) 15-bit maximal length sequencesRelative Frequency1.2 1 0.8 0.6 0.4 0.2 0−17.5 dB −20−18−16−14−12−10−8−6−4−2 0 −20−18−16−14−12−10−8−6−4−2 0 Peak Time Sidelobe Le vels (dB) Peak Time Sidelobe Le vels (dB) (a) All possib le 15 bit sequences (b) 15 bit Maximal Length SequencesNumber of Sequences9 8 7 6 5 4 3 2 1 0 ch08.indd   19 12/20/07   12:50:16 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 RANGE DETEC 
 Itisnotalwaysconvenient todirectlymodulate atransmitter in thismanner. Alternatively, thewaveform maybegenerated atalow-power levelandamplified inapoweramplifier. Thisisthemoreusualprocedure. 
 PROFILE  METER 3 
 Bush, and P. P. Datlivala: Radar Response to Vegetation II: 8-18 GHz Band. 
 Measurement of Object Height.  The basic theory of SAR assumes that the  scene is flat. To the extent that the scene is not flat, distortions in the SAR image will  result. 
 ANTENNA GAIN OF THE RADAR  'R IS THE RECEIVING 
 WIDTH SYSTEMS WHERE !$ CONVERTERS ARE NOT YET AVAILABLE WITH THE REQUIRED COMBINATION OF BANDWIDTH AND DYNAMIC RANGE TO PERFORM )& SAMPLING )MPLEMENTATION  &IGURE  SHOWS THE BASIC BLOCK DIAGRAM OF A )1 DEMODUAL 
 Characteristically, proximity fuzes use a common antenna for transmitting and receiving and hence suffer from a large leakage problem. The situation is tolera- ble only in the VHF band where the signals returned from the target (terrain or aircraft) are very large. Frequently a projectile body is used as an end-fed an-TRANSMlTTER MODULATOR MODULATOR DC AMPLIFIERAND FILTER IF OFFSET OSCILLATOR DC AMPLIFIERAND FILTER TO RECEIVER . 
 Another mathematical description ofstatistical phenomena istheprobability distrinlttioll timetioll l'(x).definedastheprobability thatthevaluexislessthansomespecified value .x P(x)=Ip(x)dx -00ord p(x)=dxP(x) (2.19) Insomecases,thedistribution function maybeeasiertoobtainfromanexperimental setof datathanthedensityfunction. Thedensity functi<?n maybefoundfromthedistribution function bydifferentiation. 2.5SIGNAL-TO-NOISE RATIO Inthissectiontheresultsofstatistical noisetheorywillbeappliedtoobtainthesignal-to-noise ratioattheoutputoftheIFamplifier necessary toachieveaspecified probability ofdetection without exceeding aspecified probability offalsealarm.Theoutputsignal-to-noise ratiothus ootained maybesubstituted intoEq.(2.6)tofindtheminimum detectable signal,which,in turn.isusedintheradarequation, asinEq.(2.7). 
 —Waveforn balace bytrigger- ing the transmitter asthe secondary current reaches zero isillustrated inFig. 13.48. Since thevoltages inthesecondary circuits arelow, the signal from thecathode resistor inthesweep amplifier isused toprovide therequired information. 
 Better components such as radiating elements,  phase shifters, and power dividers are now available. More economical solid-state  devices and memory chips have led to precision aperture phase control with correc - tions for frequency and temperature variations. Solid-state microwave devices hold  great promise for future systems where a solid-state module is associated with each  radiating element; improvements in terms of aperture control, reliability, and effi - ciency continue. 
 This allows azimuth beamwidths  to be narrower, therefore, reducing the size of clutter cells. The required coastal area  to be covered can be large, and getting the best range out of a few radar heads situated  on tall towers is often more cost effective than utilizing many smaller installations.  Because VTS often forms part of a nation’s security network, then a longer range  capability than that just required for port operations may be necessary. 
 In Autonomous Search the operator selects a range, azimuth, and elevation coverage,  and the radar searches each beam position that covers this volume once per frame. The  time it takes to complete a frame is known as the revisit or frame time. The frame time   should be minimized to enhance the cumulative probability of detection of tar gets. 
 AT DAWN, FEBRUARY 25, 1935  The first field test of Watson-Watt’s forecast of echo.  ve ne drawings are merely illustrative, and are not to be considered accurate in és  . 24 HOW RADAR WORKS  difficult but less unpromising problem of radio-detection  as opposed to radio-destruction, and the numerical con-  siderations on the method of detection by reflected  waves will be submitted.”  This, in fact, was done. 
 Mikhaylov, and A. V. Oinats,  “The correction technique for IRI model on the basis of oblique sounding data and simulation  of ionospheric disturbance parameters,” Proc. 
 With a high-resolution  radar in which the persistent sea-clutter spikes appear, the benefit of frequency agility is  decreased since the sea spikes are correlated over a relatively long period of time and appear  similar to target echoes. Thus frequency agility will be of less value the more non-Rayleigh the  clutter statistics. (If the radar is on a rapidly moving platform, the clutter might also be  decorrelated as the radar resolution cell views a different patch of clutter.)  Receiver detection criteria. 
 CODED WAVEFORMS THAT  HAVE NEAR IDEAL RANGE AND DOPPLER SIDELOBE BEHAVIOR  )N OTHER WORDS  THEIR AMBI 
 TERM AVERAGE OF   SINGLE 
 W. Sherman, and F. C. 
 S VERSATILITY ONE STEP FURTHER  WITH THE ADDITION OF TWO POLARIZATIONS   ( AND 6  ON EITHER TRANSMIT OR RECEIVE )TS  M BY  M ACTIVE ARRAY ANTENNA COM 
 /- 4HE AUTHORS WOULD LIKE TO ACKNOWLEDGE THE EFFORTS OF AND EXTEND THEIR SINCERE GRATI 
 SCAN REPRESENTED THE SPATIAL CONVOLUTION OF THE ANTENNA PATTERN WITH THE TARGET 4HE READER IS REFERRED TO &IGURE   SHOWN PREVIOUSLY  WHICH ILLUSTRATES THIS EFFECT 4HIS SPATIAL PATTERN DOES NOT REPRESENT AN IMAGE OF THE OBJECT OF INTEREST AND MUCH EFFORT HAS BEEN MADE TO DEVELOP METHODS TO RECONSTRUCT THE TARGET IMAGE FROM '02 DATA &)'52%   %NVELOPE OF ! 
 †  Inclinations greater than 90 ° are retrograde because their E-W velocity component in the ascending pass is contrary  to the direction of the Earth’s rotation, in contrast to prograde orbits whose inclinations are less than 90 °. ch18.indd   3 12/19/07   5:13:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 However, any fre - quency other than one centered in a bin will bleed into the other bins. The basic DFT  bin has a frequency response similar to sin( x)/x, which means that a signal in another  bin might bleed into a DFT frequency bin with an attenuation as small as 13 dB. To  compensate for this, the input samples can be weighted in amplitude with a wide selec - tion of weights, such as Hanning and Hamming weights, which broaden the main lobe  response of the DFT output, but reduce the amplitude of the side lobes. 
 The magnitude ofrcan easily beobtained from the fact that srotates with the doppler frequency jd. Thus theangle betweens and s’is2rf,T,and accordingly r=2ssin(mf~T). (22) This equation, which isthe same asEq. 
 ¤ ¦¥³ µ´          WHERE ERFCq  IS THE COMPLEMENTARY  ERROR FUNCTION 4HE REQUIRED 3.2 AS A FUNCTION OF  0D FOR A -ARCUM TARGET IS APPROXIMATED AS   3.2REQD &! PDI PDI PDIPDI     00 .... D 
 The sumanddifference signalsappearatthetwootherarmsofthehybrid.Onreception, theoutputsofthesumarmandthedifference armareeachheterodyned toanintermediate frequency andamplified as.inanysuperheterodyne receiver. Thetransmitter isconnected to thesumarm.Rangeinformation isalsoextracted fromthesumchannel. Adup)exer isincluded inthesumarmfortheprotection ofthereceiver. 
 89. R. Jaworowski, “Outlook/specifications military aircraft,” Aviation Week and Space Technology ,  pp. 
 the lens will be insensitive to  frequency.  RADAR ANTENNAS 249 (a)Focus--------- (b) Fi~un'7.IR(II)Converging-lens antenna constrllctcd ofhomogcncolls soliddielectric. Dircctmicrowave analogy oftheoplicallens.(11)Zoneddielectric lens. 
 Another 10dBoughttobe allowedtoaccount forvariations intheotherparameters oftheradarequation. Hencethe dynamic rangeofoperation required ofthereceiverAGCmightbeoftheorderof90dB,or perhapsmore. hisfound 10inpracticethatthemaximum gainvariation whichcanbeobtained witha singleIFstageisoftheorderof40dB.Therefore twotothreestagesoftheIFamplifier must begain-controlled toaccommodate thetotaldynamic range.Themiddlestagesareusuallythe onescontrolled sincethefirststagegainshouldremainhighsoasnottoinfluence thenoise figureofthemixerstage.ItisalsobestriottocontrolthelastIFstagesincethemaximum undistorted outputofanamplifying stageisreducedwhenitsgainisreducedbytheapplica­ tionofacontrolvoltage. 
 These signals are converted to digital form by analog-to-digital (A/D) converters, correlated with the stored binary sequence and combined, e.g., by the square root of the sum of the squares. A processing system of this type, which contains an in- phase and quadrature channel and two matched filters or correlators, is called a homodyne or zero IF system. There is an average loss in signal-to-noise ratio of 3 dB if only one channel is implemented instead of both / and Q channels. 
 58. Galati, G.: Range-tracking in Tracking Radars: Analysis and Evaluation of the Accuracy, Ril'ista  Technica Selenia (Rome, Italy), vol. 2, no. 
 J. Sangston, “Toward a theory of ultrawideband sea scatter,” in IEEE National Radar  Conference 1997 , May 13–15, 1997, pp. 160–165. 
 Most can be modified to apply to an  airborne radar for the measurement of height of other aircraft or the depression angle if a  ground target. The time-difference height-finding technique to be described is applicable, in  principle, to almost any radar situation, but in practice it is more applicable to an elevated  radar such as in an aircraft, especially one which operates over water. It derives the height of a  target from the time difference between the radar signal reflected directly from the target and  the multipath signal that arrives via reflection from the surface of the earth. 
 When the antenna is pointing ahead, the predominant effect is the variation of the center frequency corresponding to the change in a0 with range. When the an- tenna is pointing abeam, the predominant effect is the velocity spread across the antenna beamwidth. These are classified as the slant-range effect and the platform-motion effect, respectively. 
 Comm. Technology and Electronics , vol. 48, pp. 
 They occur for the same values of TT(S/\) sin 0, but the width of the lobes is reduced, and they are separated by minor lobes. Summing the vec- tor contributions from all elements, with element O as phase reference, gives t n=N-\ E (Q) - ^ £./(2ir/X) ns sin 6 VN ^o The factor 1/VTV shows that each element is energized with I/N of the (unity) input power. Normalizing the gain to unity at broadside, 0 = 0, gives the pattern sin [NTT(SIK) sin 0]EM = (7.2)N sin [TT(S/X) sin 0] Ea(Q) gives the radiation pattern for isotropic radiators and is known as the array factor. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar.  PULSE COMPRESSION RADAR  8.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 Minimum Peak Sidelobe Codes. 
 LAR INTERVALS THROUGHOUT THE LIFE OF THE ARRAY  AFTER IT HAS BEEN DEPLOYED 4HE ANTENNA MEASUREMENTS REQUIRED FOR FACTORY CALIBRATION CAN BE MADE IN THREE DIFFERENT TYPES OF ANTENNA RANGES NEAR FIELD  COMPACT  OR FAR FIELD &OR LARGE GROUND 
 L. N.: "Radar System Engineering." vol. I. 
 265 8.10 Unsynchronized Replies 268 C..,. 9. AXTENNAS, SCA~~ERS, AND STABILIZ.\TIOX. 
 16.Richards, C.J.,andM.Marchant: Structural AspeCts: ptI.Elementary DesignConsiderations, chap.7of"Mechanical Engineering inRadarandCommunications," C.J.Richards (ed.),Van Nostrand Reinhold Co.,NewYork,1969. 17.Chu.T.S..andR.H.Turrin: Depolarization Properties ofOffsetReflector Antennas, IEEETrailS.. \'01.AP-21.pp.339-345. 
 THE 
 FILTER BANDWIDTH RATIOSTYPE 3dB/6dB [NOISE/3dB RECTANGULAR I 1-000 1000ONESINGLE-TUNEDSTAGE 0.577 1.570TWO SYNCHRONOUS STAGES 0.645 1.220FIVESYNCHRONOUSSTAGES 0.683 1.114FIVE-POLE GAUSSIAN 0.707 1.077NINE-POLE GAUSSIAN 0.707 1.066INFINITE-POLE GAUSSIAN 0.707 1.065also are tabulated in terms of product of the filter bandwidth and pulse duration. Typically, the bandwidth may deviate 30 to 50 percent from the optimum value before the detectability is degraded by an additional 0.5 dB. This rather broad 4'optimum" region is centered near unity bandwidth-time product for virtually all practical filters if one uses the 6 dB definitions. 
             
 STAGE #/2$)# PROCESSOR %ACH  ROW OF THE TABLE REPRESENTS SUCCESSIVE ITERATIONS OF THE ALGORI THM 4HE  TANP I  COLUMN  SHOWS THE FACTOR BY WHICH THE ) AND 1 VALUES ARE MULTIPLIED FOR EACH ITERATION .OTE THAT  THESE VALUES ARE FRACTIONAL POWERS OF   SO THE MULTIPLICATION CAN BE REALIZED BY SHIFTING THE BINARY ) AND 1 VALUES RIGHT BY  I PLACES 4HE  P  I  COLUMN SHOWS THE ARCTANGENT OF THIS  FACTOR  WHICH CAN ALSO BE THOUGHT OF AS THE PHASE SHIFT APPLIED DURING EACH ITERATION &)'52%   #OMPLEX MULTIPLY WITH THREE REAL MULTIPLIERS                    . 
 Brandes, “Radar measurement of rainfall—a summary,” Bull. Am.  Meteorol. 
 IEEE , vol. 57,   pp. 1408–1419, 1969. 
 NENTS  INCLUDING ALL BEAM 
 (It should be noted that most of  the oceanographers’ spectra are based on measurements at relatively low frequencies  and so cannot be taken seriously at frequencies above about 2 Hz. Nevertheless, these  spectral forms are often used up to 20 Hz or greater in predicting radar clutter under  the Bragg hypothesis.) Converting this frequency spectrum into an isotropic wavenumber spectrum  through Eq. 15.2 results in a spectrum of similar form, only with a K −4 asymptote. 
 In fact, traditional GB-InSAR techniques require a radar sensor equipped with transmitting and receiving antennas, moved by a mechanical scanner to achieve the desired synthetic aperture [ 7]. This approach, even if it has proved to be simple and effective, can have a considerable impact on important operational aspects such as scanning times, maintenance and installation, which will be discussed brieﬂy below. The data acquisition time is one of the most important parameters in the evaluation of a remote sensing monitoring system; since the ﬁrst GB-InSAR introduction, the scanning times have been signiﬁcantly reduced, and currently the fastest systems can scan the entire 360◦circular sector in just Sensors 2019 ,19, 252; doi:10.3390/s19020252 www.mdpi.com/journal/sensors 119. 
 Close to carrier phase modulation is typically dominated by that of the oscillators  due to the inherent feedback process within the oscillator circuitry. Noise contribu - tors within the oscillator loop that exhibit a 1/ f characteristic (10 dB/decade) noise  slope, are enhanced by 20 dB via the feedback mechanism with a resulting net 1/ f 3  characteristic (30 dB/decade) noise signature close to carrier, within the oscillator loop  bandwidth. Outside this loop bandwidth, the oscillator noise signature resumes a 1/ f  slope until reaching a flat thermal noise floor. 
               . n°£È  2!$!2 (!.$"//+  0HASE 
    
 OD stub-supported line with appropriate couplings has been worked out for the 3-cm band. The largest stub-supported standard coaxial line isin 1~-in. OD tubing, with stubs designed forthe 9-to1l-cm band; the higher-mode limit prohibits anything larger onthis band. 
 DOMAIN AND FREQUENCY 
 Because of foldover, a frequency which  lies to one side of the IF carrier appears, after detection, at the same video frequency as one  which lies an equal amount on the other side of the IF. Therefore the sign of the doppler shift is  lost with a video filter bank, and it cannot be directly determined whether the doppler  frequericy corresponds to an approaching or to a receding target. (The sign of the doppler may  he determined in the video by other means, as described later.) One advantage of the foldover  in ttie video is that only half the number of filters are required than in the IF filter bank. 
 One method of generating a fan beam is with a parabolic reflector shaped to yield the . (al  (bl THE RADAR EQUATION 55  Figure 2.17 (a) Pencil-beam antenna pattern; (b)  fan-beam-antenna pattern.  proper ratio between the azimuth and elevation beamwidths. 
 The radar in this case is illuminating FIGURE 5.29  Inverse SAR notion45 FIGURE 5.30  Single ISAR ship image45 ch05.indd   32 12/17/07   1:27:13 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 
 J. L., and G. E. 
 STATE #-2v IN 3ECTION  6ERTICAL ,OBING  #LUTTER IS NOT THE ONLY CAUSE OF DETRIMENTAL PERFORMANCE OF  MARINE RADAR $IRECT REFLECTIONS FROM A TARGET ARRIVE AT THE RADAR ANTENNA AND COMBINE VECTORIALLY WITH TARGET REFLECTIONS THAT HAVE ALSO BEEN REFLECTED BY THE SEAS SURFACE 4HIS EFFECT PRODUCES A SUMMED SIGNAL AT THE RADAR ANTENNA THAT IS A FUNCTION OF BOTH THE TARGET HEIGHT AND THE RADAR ANTENNA HEIGHT ABOVE THE SEA  AS THESE AFFECT THE PATH LENGTH DIFFERENCE OF THE DIRECT AND REFLECTED RADIATION /BVIOUSLY  THE EFFECT IS RECIPROCAL FOR BOTH TRANSMIT AND RECEIVE PATHS  &OR A POINT TARGET  AND A SEA OF DEFINED ROUGHNESS  THE  CALCULATION TO DETERMINE THE RESULTANT EFFECT IS RELATIVELY STRAIGHTFORWARD AND RESULTS IN THE CLASSIC LOBING PATTERN SEE  FOR EXAMPLE  "RIGGS   &OR A TARGET WITH REASONABLE  VERTICAL EXTENT  SUCH AS A SHIP  THE LOBING STRUCTURE BECOMES VERY COMPLEX AND IS LESS LIKELY TO PRODUCE TROUBLESOME NULLS  (OWEVER  THE DETECTION OF  A SMALL TARGET  SUCH AS .   #)6), -!2).% 2!$!2   ÓÓ°Ç A BUOY OR A PLEASURE CRAFT  ENHANCED BY A RADAR REFLECTOR CAN CREATE SIGNIFICANT VERTICAL  LOBING EFFECTS THAT CAN BE A PROBLEM TO THE USER )N PARTICULAR  IN VERY CALM SEAS PRO 
 J., vol. 27, pp. 58 82, January, 1948. 
 WEIGHTING LOSS )F A CANCELER IS USED  FILTER WEIGHTING CAN BE RELAXED OVER THAT WITH A FILTER BANK ALONE  SINCE THE CANCELER REDUCES THE DYNAMIC 
 MILES RANGE 2ANGE TRACKING USUALLY PROVIDES THE MAJOR MEANS FOR DISCRIMINATING THE DESIRED TARGET FROM OTHER TARGETS ALTHOUGH DOPPLER FREQUENCY AND ANGLE DISCRIMINATION ARE ALSO USED  BY PERFORMING RANGE GAT 
 ING YET THESE REQUIREMENTS ARE WILLINGLY ACCEPTED IN ORDER TO ACHIEVE THE SIGNIFICANT BENEFITS OFFERED BY DOPPLER )T SHOULD ALSO BE MENTIONED THAT THE DOPPLER SHIFT IS THE KEY CAPABILITY OF A RADAR THAT CAN MEASURE SPEED  AS BY ITS DILIGENT USE BY TRAFFIC POLICE FOR MAINTAINING VEHICLE SPEED LIMITS AND IN OTHER VELOCITY MEASURING APPLICATIONS £°{Ê / 
 Ascanning rate of360/see gives anangular motion of0.07° between transmission ofapulse and return ofthe echo from atarget at200-mile range. Ifthe beamwidth were much less than 0.07°, the antenna gain forreception ofthesignal would begreatly below normal. For abeam- width ofabout 0.15° or0.2° this effect becomes negligible, and the limit itsets onbeamwidth isprobably not ofpractical importance. 
 The patterns or the spurious beams are of similar shapc as  the original pattern but are displaced in angle and reduced in amplitude.  Random errors in reOectors. The· classical work on the effects of random errors on antenna  radiation patterns is due to Ruze.73•99•101 He pointed out that in a reflector antenna, only the  phase error in the aperture distribution need be considered. 
 Such a radar is less susceptible to a DRFM repeater because  (i) the jammer cannot adapt easily since the radar signal is varying in the PRI  domain, and (ii) the signal transmitted by a DRFM repeater jammer at a given  PRI (i.e., the radar signal that is used by the SAR at the previous PRI) is approxi - mately orthogonal to the radar signal that the SAR is utilizing at the current PRI,  and thus, a matched filtering with the current PRI radar signal would weaken the  DRFM repeater jammer signal. In Soumekh167 a novel method is outlined that  combines the above mentioned pulse diversity radar signaling with a new coher - ent two-dimensional processing of the measured data to effectively suppress a  DRFM repeater jammer. ISAR . 
 CRT display is also apt to become  a nuisance for altimeter work. The picture on the CRT  is helpful to the navigator for range and bearing, for  PPI pictures, and for many other purposes. But in the  field of altimeters all he wants to know is, “‘ What is the  altitude?” ‘The answer is perhaps best shown on an  instrument dial rather than with the electric pencil-point  of the CRT. 
 ~vedif interference  is not a problem, the upper limit of spectral width, about 100 kHz, is set by the dispersive  nature of the ionosphere. Doppler filter bandwidths for separating targets from clutter in an  OTH radar might range from 1 Hz down to 0.05 Hz or less, depending on the target's chara  teristics and the stability of the propagation path. The pirlse repetition frequency (prf) of a  OTH radar is generally low to avoid range ambiguities. 
 The  important resolution cell size factors, viz. receiver antenna beamwidth and spectral  bandwidth, are not explicitly contained in Eq. 20.2 (Clutter frequently sets the limit  to target detectability; in which case, it is the signal-to-clutter ratio rather than the  signal-to-noise ratio that is of interest. 
 The radiation pattern is equal to the norn~alized square of the amplitude, or 1 ; 1 =  / E, l2 sin2 [Nn(ii/A) sin 81 G,(O) = ---- - =  N2 N2 sin2 [n(d/A) sin 01 sill [Nn(tl/A) sin (I] . -.  sin [n(rl/A) sin 01  If tlie spacinQ between antenna elements is A12 and if the sine in the denominator of Eq. 
 Figure 24.7 examines one particular segment and time. These observations were made with 5-kHz-bandwidth filters. When narrower- bandwidth filters with steep skirts are used, several channels 5 to 10 kHz wide with no detectable users are generally found within any 1-MHz span. 
 J. R. Moore and W. 
 Also, if the antenna  p;ctrerri is a rlarrow per~cil beam arid if the searcli volume is large, a relatively lorig time rniglit  be rcqirired to find the target. Therefore many radar tracking systems employ a separate searcli  rnciar to provide tlie inforrnatiori necessary to position the tracker on the target. A search  radar. 
 4(% 
 PURPOSE DATALINK EQUIPMENT IS THE LOW POWER 
 Ne~York.1970. 38.Skolnik, M.I.:SurveyofPhased ArrayAccomplishments andRequirements forNavyShips. ..Phased ArrayAntennas." cd.byA.A.OlinerandG.H.Knittel, ArtechHouse,Dedham. 
 TIONS IN THE RADAR COMPUTER 4HESE DETECTIONS ARE THEN USED TO  FORM AND UPDATE TRACK  FILES 4HE ANTENNA SCANS IN A NORMAL SEARCH PATTERN  AND A SCAN 
 With real waveforms, the sidelobes in the  plateau region can be higher than might be desired. Furthermore, the extent of the platform  increases as the spike is made narrower since the total volume of the ambiguity function must  be a constant, as was given'by Eq. (1 1154). 
 Somewhat higher ratios canbe used byinserting aresonant circuit inthe cathode.. SEC. 139] ELECTRONIC SWITCHES 503 The device canbeused asa“single stroke” pulse generator ifthegrid isbiased beyond cutoff. 
 A., J. Clarke, and R. S. 
 There are  a variety of GO-based pattern reflector analysis methods, all of which are rooted in ray  tracing and some of which are augmented with diffraction terms for improved accuracy.  Although the simple GO method (no diffraction terms) works reasonably well, it is not  generally as accurate as PO. However, two of the more common enhanced methods,  Geometrical Theory of Diffraction (GTD) and Uniform Theory of Diffraction (UTD),45  include edge diffraction and are much more accurate. 
 OF 
 Tre  \ . fr.t, Lrt  Sidelobe ond bock -lobe  radiation 'iJL  Figure 12.12 Contributions to the total system effective noise temperature.  effect of the sidelobes may be neglected, and the total system effective noise Temperature 1;. 
 GUITIES UNLESS THE DOPPLER SPECTRUM IS LIMITED PRIOR TO 02& REDUCTION !MBIGUITIES 4HE 02& GENERATES A TWO 
 Tracking radarsthatarebasedonCW,pulse-doppler, orMTIprinciples canalsotrackthedoppler frequency shiftgenerated byamovingtarget.Thismaybeaccom­ plishedwithafrequency discriminator andatunableoscillator tomaintain thereceivedsignal inthecenterofanarrow-band filter.Itisalsopossible touseaphase-lock loop,orphase-.J sensitive discriminator whoseoutputdrivesavoltage-controlled oscillator toholditsphasein stepwiththeinputsignal. 2Tracking thedoppler frequency shiftwiththeequivalent ofa narrow-band filterjustwideenoughtoencompass thefrequency spectrum ofthereceived signalallowsanimprovement inthesignal-to-noise ratioascompared withwidebandproces- sing.Itcanalsoprovideresolution ofthedesiredmovingtargetfromstationary c!uller.The doppler tracking filterissometimes calledaspeed gate. 5.9COMPARISON OFTRACKERS' Ofthefourcontinuous-tracking-radar techniques thathavebeendiscussed (sequentiallobing, conicalscan,amplitude-comparison monopulse, andphase-comparison monopulse), conical scanandamplitude-comparison monopulse haveseenmoreapplication thantheothertwo. 
 DIMENSIONAL ARRAY OF SIGNALS SAMPLED AT DIFFERENT INSTANCES OF TIME AND AT DIFFERENT SPATIAL LOCATIONS 34!0 IS A FAIRLY BROAD TOPIC THAT HAS APPLICABILITY BEYOND THIS CHAPTER ON AIRBORNE -4) RADAR 4HE PRIMARY MOTIVATION FOR 34!0 IS TO IMPROVE CLUTTER CANCELLATION PERFOR 
 Ê"Ê-, &OR AIRBORNE OR SPACEBORNE GROUND 
 The B sandwich is the "inverse" of the A sandwich. It is a three layer structure whose  quarter-wave-thick skins have a dielectric constant lower than that of the core material. The B  sandwich is the microwave analog of matqhing coatings used in optical lenses. 
 (ILL    , 2 2ABINER AND " 'OLD   4HEORY AND !PPLICATION OF $IGITAL 3IGNAL 0ROCESSING  %NGLEWOOD  #LIFFS  .* 0RENTICE 
 The usual rule-of-thumb criterion employed in antenna practice is that the.  phase of the actual wavefront must not differ from the phase of the desired wavefront by more  than + 1/16 in order to ensure satisfactory performance. The application of this criterion to a  reflector antenna requires the mechanical tolerance of the surface to be witl~in ?1/32. 
 35. Moore, R. K.: Ground Echo, chap. 
 AP-24, pp. 11 17. January. 
 Johnson, M.A., and D. C. Stoner: ECCM from the Radar Designer's Viewpoint, If.EE Eleccro 76,  Boston, May 11--14, 1976, paper 30-5, Reprinted in Microwm•e Journal, vol. 
 J.: "Tlie lJse of Radar at Sea." Hollis and Carter. Ltd.. London. 
 The basic SAR interferometric environment is one in which there is a pair of  mutually coherent images that have embedded phases that depend on the details of  viewing geometry and scene structure. The coherently combined images are known  as an interferogram, which typically contains fringes that express the interactions  between the phase structure of the two data sets. Signal processing is designed to  estimate these phase differences, and to deduce geophysical parameters of interest  from the resulting measurement.49 The interferometric signal model is simple in concept. 
 Therefore, when using published computations of probability of detection it should  be noted whether the effect of the beam shape has been included. In this text, this approach is  not used. Instead a beam-shape loss is added to the radar equation to account for the fact that  the maximum gain is employed in the radar equation rather than a gain that changes pulse to  pulse. 
 Keywords: land subsidence; Radarsat-2 images; small baseline subset (SBAS) method; interferometric synthetic aperture radar (InSAR) 1. Introduction Land subsidence is deﬁned as a gradual settling or sudden sinking of the ground surface [ 1–3], which results from natural processes or human activities [ 4–7]. Over the past decades, numerous land subsidence events have been reported in many cities around the world where the rapid urban construction and the extensive groundwater exploitation are taking place [ 8–13]. 
 Okean, H. C., and A. J. 
 SPOND TO CLUTTER AT A GRAZING ANGLE OF   THAT IS  FOR A RADAR LOOKING STRAIGHT DOWN  /N A STRICTLY EMPIRICAL BASIS  THE CLUTTER CROSS SECTION AT THIS ANGLE IS ONLY WEAKLY DEPENDENT ON FREQUENCY  HAS A MAXIMUM OF ABOUT  D" AT ZERO WIND SPEED AT LEAST FOR THE ANTENNA BEAMWIDTHS AND EXPERIMENTAL CONFIGURATIONS REPORTED   AND FALLS OFF GRADUALLY AS THE WIND PICKS UP 3CATTERING AT HIGH GRAZING ANGLES IS COMMONLY REGARDED AS A FORM OF SPECULAR SCATTERING FROM TILTED FACETS OF THE SURFACE  SO IT IS OF INTEREST TO NOTE THAT THERE APPEARS TO BE A SMALL RANGE OF ANGLES IN THE NEIGHBORHOOD OF   FOR WHICH THE CROSS SECTION IS ALMOST COMPLETELY INDEPENDENT OF WIND SPEED  3INCE THESE ANGLES CORRESPOND TO COMPLEMENTS OF THE COMMON RMS SEA SLOPE ANGLES OF ABOUT   IT MIGHT BE ARGUED THAT AS THE WIND INCREASES  THE CLUTTER  DECREASE DUE  TO INCREASING SURFACE ROUGHNESS IS BALANCED BY A CLUTTER  INCREASE DUE TO AN INCREASING  POPULATION OF SCATTERING FACETS 4HIS LINE COULD  THEREFORE  BE REGARDED AS THE BOUND 
 661–670, 1970. 138. J. 
 Richards, “A beginner’s  guide to interferometric SAR concepts and signal processing,” IEEE Aerospace and Electronic  Systems Magazine , vol. 22, no. 9, Part 2: Tutorials, pp. 
 MENTS CALL FOR A SUPPRESSION OF STATIONARY LAND CLUTTER BY  D" AND A SUPPRESSION OF MOVING CLUTTER RAIN  BY  D" &OR THE FILTER DESIGN  A CLUTTER ATTENUATION  D" BELOW THESE REQUIREMENTS WILL BE NEEDED TO KEEP THE SENSITIVITY LOSS DUE TO THE CLUTTER RESIDUE BELOW  D" AND ALSO BECAUSE EACH DOPPLER FILTER WILL HAVE A COHERENT GAIN OF AROUND      LOG    D"  THIS MUST BE ADDED TO THE FILTER DESIGN SPECIFICATION AS WELL 4HE  TOTAL 3 
 Any energy which leaks through the TR tubes (shown by the  dashed lines) is directed to the arm with the matched dummy load and not to the receiver. In  addition to the attenuation provided by the TR tubes, the hybrid junctions provide an addi­ tional 20 to 30 dB of isolation.  On reception the TR tubes are unfired and the echo signals pass through the duplexer and  into the receiver as shown in Fig. 
 This results because a large number of solid-state devices must be combined to provide the power for a radar transmitter, and they are easily combined in ways that degrade gracefully when individual units fail. Overall power output, in deci- bels, degrades only as 20 log r, where r is the ratio of operating to total amplifiers. 6. 
 177.  3. Van Vlcek. 
 BANDWIDTH PRODUCT OF THE CODED PULSE INDICATES THE ADDED DYNAMIC RANGE THAT THE DECODER WILL EXTRACT FROM THE POINT TARGETS #ONVERSELY  IF THE RADAR INCORPORATES AN EXCESSIVELY WIDE 
 PHASE STATES  AND HYDROMETEOR WATER OR ICE PARTICLES  TYPES IN DIFFERENT CLASSES OF PRECIPITATION AND CLOUDS 4HE CAPABILITIES OF MULTIPLE 
 Furthermore, designs vary significantly depending upon many  factors, including platform, reflector size, environment, frequency of operation, scan/ FOV , and cost constraints. Although it is not within the scope of this chapter to address  mechanical design in detail, a brief survey of design factors and considerations pro - vides some useful insights.  The platform, i.e., vehicle, or installation site is a significant driver for radar sen - sors in general, including the antenna. 
 18.2. The original tracking radars of this type, such as the SCR-268, used an array of radiating el- ements which could be switched in phase to provide two beam positions for the lobing operation. The radar operator observed an oscilloscope that displayed side by side the video returns from the two beam positions. 
 This typically results in database updates and/or new antenna job requests from  the client. New activities can be added at any time using this modular approach. Although this structure is complex and the software encompasses millions of lines  of code, modern MFAR software integrity can be maintained with strict control of  interfaces, formal configuration management processes, and formal verification and  validation software tools. 
  1SINP       1   )SINP       1COSP      4HESE EQUATIONS CAN BE MANIPULATED TO PROVIDE  )   COSP   ;)  
 Evans, “Radio techniques for the measurement of ice thickness,” Polar Record , vol. 11,   pp. 406–410, 1963. 
 T. Ulaby, R. K. 
    $ECEMBER     * 6 (ARRINGTON  h!N ANALYSIS OF THE DETECTION OF REPEATED SIGNALS IN NOISE BY BINARY INTEGRATION v  )2% 4RANS  VOL )4 
 The newer Range Migration Algorithm  (RMA) (see Chapter 10 of Carrara et al.3),  originally developed for seismic applications, provides the most theoretically correct  solution to the stripmap image problem. It does not make a far-field approximation but  treats the wavefronts as spherical. It is particularly applicable to SAR with very wide  fractional bandwidth and/or wide synthetic aperture angle. 
 (b)Hole-and-slot-type magnetron. (c)Vane-type m~gnetron. The simplest isperhaps the slot type (Fig. 
 Since the transistor cannot operate efficiently with the low  duty-cycles characteristic of conventional radars, radars using transistors must operate with  long pulses or high pulse repetition frequency. Neither is desirable except in special cases (as in  pulse-doppler radar or CW radar). Long pulses result in a long minimum radar-range since  the receiver cannot be turned on until the transmitted pulse is turned off. 
  D" REJECTION TO o  &IGURE  B SHOWS THE FILTER THAT RESPONDS TO TARGETS AS NEAR AS POSSIBLE TO ZERO  DOPPLER  WHILE HAVING A ZERO 
 BAND USERS IN THE SAME FREQUENCY BAND WITHOUT CAUSING INTERFERENCE !NOTHER CLASS OF VARIATIONS INVOLVES DEPARTING FROM A LINEAR FREQUENCY MODULATION "Y VARYING THE FREQUENCY 
 A pulse radar that extracts the doppler frequency shift for the purpose of detecting moving  targets in the presence of clutter is either an MT/ radar or a pulse doppler radar. The distinc­ tion between them is based on the fact that in a sampled measurement system like a pulse  radar, ambiguities can arise in both the doppler frequency (relative velocity) and the range  {time delay) measurements. Range ambiguities are avoided with a low sampling rate (low pulse  repetition frequency), and doppler frequency ambiguities are avoided with a high sampling  rate. 
 The echo signal received at the radar is  sin [2rrf0(t -T)]. If the transmitted and received signals are compared in a phase detector,  the output is proportional to the phase difference between the two and is 11</> = 2rrf0 T =  4rrf~ R/c. The phase difference may therefore be used as a measure of the range, or  R = ~ l1</> = 3_ 11</>  4~fo 4n (3.17)  However, the measurement of the phase difference 11</> is unambiguous only if 11</> does not  exceed 2n radians. 
 OF 
 Range-IPP cells where RFI is detected are then  “repaired” to prevent corruption of the output spectrum. The filter bank is usually  realized by using the fast Fourier transform (FFT); however, the discrete Fourier  transform (DFT) can be used when the number of filters is small. Appropriate  weighting is employed to reduce the filter sidelobes. 
 The ﬁrst category is scatter-based algorithms, such as dominant scatter processing (DSP) method [ 12,13], phase gradient Sensors 2019 ,19, 1154; doi:10.3390/s19051154 www.mdpi.com/journal/sensors 277. Sensors 2019 ,19, 1154 autofocus (PGA) method [ 14–16]. The DSP method is intuitive in concept and easy to implement, but it needs high-quality prominent point in echo, otherwise the image is inferior [ 13]. 
 LINE ARRAYS FEEDS THE ALERT RECEIVER WHICH DETECTS THE PRESENCE OF RADIO ENERGY IN EXCESS OF PRESET THRESHOLD LEVELS 4HE REFLECTED ENERGY IS ALSO SIMULTANEOUSLY RECEIVED ON OTHER ARRAYS THAT ARE SEPARATED IN THE EAST 
 23. International Hydographic Organization, www.iho.shom.fr. 24. 
 Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 23.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 Year  reportedRef Organization Author Surface Composition# Data  Curves /  FiguresFrequency  (GHz)Measurement Angles (degrees) Polarization      qi      qs     f 196590 196891 The Ohio State  University  Antenna Lab.Cost, Peake Smooth sand Loam Foliage, soybean Rough sand Loam with stubble Grass179 / 32          10     10 VV HH HV       VV HH HV60 – 85   20 – 80     20 – 8560 – 85   0 – 85       0 – 850 – 145 0, 180    0 – 180 196692   196793 Johns Hopkins  Univ. (APL)Pidgeon Sea (sea states 1, 2, 3)   Sea (Beaufort wind 5)7 / 1 1 / 1C band     X bandVV VH     HH87 – 89.9     82 – 89  0 – 80     45 – 78180    180 196794      196895   196996 GEC  Electronics  Ltd., EnglandDomville Rural land Urban land Forest Sea  Semi-desert, wet77 / 4X band       X band   X bandVV      VV HH   VV HH  0 – 90         0 – 90     0 – 90  0 – 90        0 – 90     0 – 900, 165, 180      0, 165, 180  0, 165, 180 TABLE 23.3  Summary of Measurement Programs for Bistatic Scattering Coef ficient, σB0 (In-plane data is shown in bold type—see subsequent text.)   (after M. 
 CAL ANGULAR RESPONSES 4HESE CURVES ARE FOR  '(Z  BUT THE RESULTS WOULD BE SIMILAR AT ANY FREQUENCY DOWN TO 3 BAND &IGURE   SHOWS THE FREQUENCY VARIATION OF  R   FOR VARIOUS KINDS OF ICE 3HORE 
 Scudder, R. M.. and W. 
 ANGLE GAIN ANTENNAS  4WO 
 13.16 The first method involves theuseofclamps mswitches inthesecond- ary circuit toforce the potential orthe current tozero inthe interval between sweeps. Solong asthe sweep component has agiven polarity, this can bevery simply accomplished inthe potential case byad-c restorer (See. 13“9),and inthecurrent case byaselenium rectifier inseries with the secondary circuit. 
 In  a practical antenna this will not necessarily be true since there will always be some unavoid­ a hie phase variations caused by the inability to fabricate the antenna as desired. Any practical  device is never perfect: it will always be constructed with some error, albeit small. The phase  variations due to the unavoidable errors can cause the sidelobe level to be raised and the gain  to he lowered. 
 SCAN AND AN EXAMPLE IS SHOWN IN &IGURE  4HIS EFFECTIVELY REPRESENTS ONE AXIS Z  DEPTH AND THE ORTHOGONAL AXIS  X OR Y  LINEAR POSITION 4HE AMPLITUDE OF THE SIGNAL MAY BE SHOWN  AS A SERIES OF OVERLAPPING SIGNALS OR  ALTERNATIVELY  A hWIGGLE PLOTv BORROWED FROM SEISMIC TERMINOLOGY  OR A GRAYSCALE 
 32.Li,T.:AStudyofSpherical Reflectors asWide-angle Scanning Antennas, IRETram.,vol.AP-7, pp.223-226, July,1959. 33.Spencer, R.c.,andG.Hyde:StudiesoftheFocal-Region ofaSpherical Reflector: Gcomdric Opti~s, IEEETrans.,vol.AP-16,pp.317-324, May,1968. 34.Love,A.W.:ScaleModelDevelopment ofaHighEfficiency DualPolarized FeedfortheAre~ibo Spherical Reflector, IEEETrans.,vol.AP-21,pp.628-639, September, 1973. 
 ETERS SINCE THEN 3EASAT WAS DESIGNED TO MEASURE GLOBAL OCEAN DYNAMIC TOPOGRAPHY  AS WELL AS WAVE HEIGHT AND SURFACE WIND SPEED 'EOSAT  4HIS ALTIMETERS DESIGN  WAS PATTERNED CLOSELY AFTER THAT OF THE 3EASAT  ALTIMETER 'EOSAT WAS A 53 .AVY MILITARY SATELLITE WHOSE PRIMARY MISSION WAS TO MAP THE %ARTHS MARINE GEOID TO THEN 
 TION ON THE LEADING EDGE OF THE PULSE AND IN ITS SUBSEQUENT DEVELOPMENT )N RADARS DEMANDING HIGH CLUTTER SUPPRESSION IN EXCESS OF  D"   IT HAS SOMETIMES BEEN FOUND NECESSARY TO PREVENT THIS VARIABLE REFLECTED POWER FROM BEING RADIATED BY USE OF BOTH A CIRCULATOR AND AN ISOLATOR IN THE RECEIVE PATH 3PURIOUS 2ESPONSE OF -IXERS  4HE IDEAL MIXER ACTS AS A MULTIPLIER  PRODUCING AN  OUTPUT PROPORTIONAL TO THE PRODUCT OF THE TWO INPUT SIGNALS 4HE INPUT 2& SIGNAL AT FRE 
 Tobedetectable, asignal must have acertain minimum power; let uscall the minimum detectable signal tlti~. Then the maximum range ofaradar setonatarget ofagiven type will bedetermined bySmi., according totheexpression S.n =g, where Kisaconstant and Ptisthe power inthe transmitted pulse, to which thereceived signal power willclearly beproportional. Rearranging, ()?’4 R-= ~. 
 7Theprotection requirements fortraveling-wave tubesaresimilar. 208 INTRODUCTION TO RADAR SYSTEMS  to those of the klystron, but they are generally more difficult than for the klystron. In some  traveling-wave tubes with coupled-cavity circuits, oscillations appear for an instant during the  turn-on and turn-off portions of the pulse.' They are called rabbit-ear oscillations because of  their characteristic appearance when the RF envelope of the pulse waveform is displayed  visually on a CRT. 
 Wiesbeck, S. Riegger, "A complete error model for free space polarimetric mea s- urements", IEEE Transactions on Antennas and Propagation, vol. 39, no. 
 DESIGN OFALIGHTWEIGHT AIRBORNE RADAR FOR NAVIGATION The next example ofradar system design tobedescribed could scarcely bemore different. Inthedesign oftheground radar setdescribed, every- thing was subordinated toattaining the best possible performance; intheAX/APS-10, thesetnow tobedescribed, performance was impor- tant, asalways, but ithad tobeattained within avariety ofstrict limitations. These limitations dealt with total weight, size, and po~ver consumption, and with the required simplicity ofoperation, main- tenance, and repair. 
 3 1. Vadus, J. R.: A New Tactical Radar, Odnatlce, vol. 
 Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft.  MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 to match filter (both in range closure and phase history) the doppler spread since iso- range and iso-dopplers are not close to orthogonal near the aircraft velocity vector (see  Figure 5.8). SAR, on the other hand, is usually fully matched (relative to the desired  resolution and phase history) in every range-doppler cell. 
 Hall, W. M., and D. K. 
 Use of the previously described feeds for circular polarization would require the waveguide circuitry to be prohibitively complex. Consequently, a five-horn feed is used as illustrated in Fig. 18.15. 
 In the other. f1 can take any value except 180".  Consider first the case where {J =f= 180°, for which the following theorem applies:" In the  limit of vanishing wavelength the bistatic cross section for the transmitter direction k and  receiver djrection ;10 ~s equal to the monostatic cross section for the transmitter-recei~er  direction k + ir0 with k =f= ir0 for bodies which are sufficiently smooth." In the preceding, k is  the unit vector directed from the transmitter to the target and ii0 is the unit vector directed  from the receiver to the target. 
 - ,*/" -ÊEÊ76 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing.  RADAR DIGITAL SIGNAL PROCESSING  25.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 a variety of functions, including sine, cosine, vector rotation (phase shift), polar-to- rectangular and rectangular-to-polar conversions, arctangent, arcsine, arccosine, and  vector magnitude, through an iterative process that just uses bit shifts and adds.8 The  following discussion describes the CORDIC algorithm. 
 446 THE RECEIVING SYSTEM—RADAR RECEIVERS [SEC. 124 and thebandwidth bytheequation 11 ‘= %R~C’(3) where Cis thetotal capacity resonated byL. Hence thegain-bandwidth product is ~xa=~~ 2rc“(4) From Eq. 
 Div. Kept. /?81-152, Santa Barbara, Calif., 1981. 
 26, 1951. 58. J. 
 The hard-tube modulator, however, is  generally of greater complexity and weight than· a line-type modulator.  Tube protection.1•27 Power tubes can develop internal flash arcs with little warning even  though they are of good design. When a flash arc occurs in an unprotected tube, the capacitor­ bank discharges large currents through the arc and the tube can be damaged. 
 The circuit isthen quiescent until anexternal signal renders thegrid conducting. The regenerative action takes place asbefore, except that after itisover thegrid returns toapoint beyond cutoff where itremains until anew signal isreceived. Thecircuit isoften usedin this form asameans ofgenerating sharp pulses from poorer ones, from steep wavefronts (which are differentiated toform the triggering impulse), from sine waves, and soon. 
 24, no. 4, July 1988. 27. 
 J. IEE.  \,ol. 
 As a safety precaution, areas of high power density should be fenced off, locked, or  otherwise made inaccessible when transmitting. Personnel should never look into an open  waveglide or antenna feed horn connected to energized transmitters. When personnel must  work in areas where the power density is at a dangerous level, they shoilld be protected with  screened enclosures or with protective apparel made from reflective material. 
 Suchradomes canoperatewithhigh transmission efficiency atalmostallradarfrequencies. Materials includesingle-ply neoprene­ coatcdtcrylcne ornylonfabric,Hypalon-coated Dacron, andTeflon-coated fiberglass. lnnation pressures areinthevicinityof0.5Ib/in2gauge.Air-supported radomes canbefolded intoasmallpackage whichmakethemsuitable fortransportable radarsrequiring mobility andquickerection times.Typically, a50-ftradomecanbeinstalled ataprepared siteinabout oneortwohours.135Theyarealsoofinterestonstaticsiteswherewideband frequency operation isdcsired.Oneofthelargestexamplesoranair-supported radomewasthe210ft diameter radome fortheBellTelephone SystemTelstarsatellite communication antenna at Andover. 
 46.Scholtz, R.A.,J.1.Kappl,andN.E.Nahi:TheDetection ofModerately Fluctuating Rayleigh Targets,IEEETrans;,vol.AES-12, pp.117-125, March,1976. 47.Mooney, D.H.,andW.A.Skillman: Pulse-doppler Radar,chap.19of"RadarHandbook," M.I. Skolnik (ed.).McGraw-Hill BookCo.,NewYork,1970. 
 The detailed effects ofsurface reflection which influence coverage are very complex. Some ofthe more important effects and conclusions aresummarized below (see also Sec. 2.12). 
 M. Headrick, and D. B. 
 11l.~t.RadioEllgrs.. vol.22.pp..105-.1IR. April,1961. 
 On reception, the effect is to smear or distort  the echo pulse. It is possible to compensate for the delay in the series-fed array and avoid  distortion of the main beam when the signal spectrum is wide by the insertion of individual  delay Jines of the proper length in series with the radiating elements.19  In a series-fed array containing N phase shifters, the signal suffers the insertion loss of a  single phase shifter N times. In a parallel-fed array the insertion loss of the pltase shifter is  introduced effectively but once. 
 Rowe (later to become famous  as the head of the Malvern Telecommunications  Research Establishment of M.A.P., where so much  wartime radar apparatus was devised) as Secretary. The  committee.found the problem tremendous, and turned  to outside experts with a number of long-shot sugges-  tions, even including the possibility of a death-ray!  So, in 1935, Watson-Watt was approached by a  member of the committee, and after laughing away the  suggestion of a death-ray as an aerial weapon was asked  for his views. While admitting that he took a poor  view of the chances of a death-ray, and that his own  memorandum The Damaging Effect of Radio Beams was  mot miended to be read as a monograph on death-rays, Watson-Watt completed his report with the optimistic  _ ‘Rete: “Meanwhile-attention is being turned to the still  . 
 2010 ,58, 4108–4120. [ CrossRef ] 18. Candes, E.; Romberg, J.; Tao, T. 
 thegaussian densityfunction hasabell-shaped appearance and isdefinedby 1-(x-xo)2p(x)=J 2exp 22 (2.15)2n(1 (1 whereexp[ ]istheexponential function, andtheparameters havebeenadjusted tosatisfythe normalizing condition ofEq.(2.10).Itcanbeshownthat .00 mt=Ixp(x)dx=Xo •-00m2=rlX)x2p(x)dx=x5+(1: •-IX) Theprobability densityofthesumofalargenumberofindependently distributed quanti­ tiesapproaches thegaussian probability-density function nomatterwhattheindividual dis­ tributions maybe,provided thatthecontribution ofanyonequantity isnotcomparable with theresultant ofallothers.Thisisthe(entrallimit theorem. Another property ofthegaussian distribution isthatnomatterhowlargeavaluexwemaychoose,thereisalwayssomefinite probability offindingagreatervalue.Ifthenoiseattheinputofthethreshold detector were trulygaussian, thennomatterhowhighthethreshold wereset,therewouldalwaysbeachance thatitwouldbeexceeded bynoiseandappearasafalsealarm.However, theprobability diminishes rapidlywithincreasing x,andforallpractical purposes theprobability ofobtaining anexceedingly highvalueofX,isnegligibly small. TheRayleigh probability-density function isaisoofspecialinteresttotheradarsystems. 
 ch13.indd   73 12/17/07   2:41:17 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 SWITCH  MODULATOR PERMITS GREATER FLEXIBILITY AND  PRECISION THAN THE LINE 
 The detectability ofasignal onthePPI can beroughly measured bythe area under thevoltage pulse. Thus ifthe trigger and signal delay lines differ indelay time byanamount A71, there will betwo uncanceled spikes ofwidth A71foreach echo. Inorder to cancel, forexample, to4percent, wemust therefore make A~lless than 2per cent ofthe pulse length. 
 The full 360° azimuthal pattern sees velocities from -Vg to +Vg. The compensation circuits offset the velocity by an amount corresponding to the antenna boresight velocity VB, but the total range of doppler frequencies corresponding to 2Vg is obtained because of echoes received via the sidelobes. For airborne systems with low and medium PRFs, these doppler frequencies can cover several multiples of the PRF so that the sidelobe power is folded into the filter. 
 FIELD RADIATION PATTERN &OR MORE COMPLEX GEOMETRIES  EG  OFFSET 
 2.18 except fre-  quency is 9225 MHz (X band). VH and  0 -lo -20 -30 -40 -10 -20 -30 -40 HV represent cross-polarized components.  (bl Elevot~m orpect angle[aeg) (CI (From Olin and Q~een.~')  42INTRODUCTION TORADAR SYSTEMS Figure2.t8(a)Azimuth variation ofradar crosssectionofaC-54aircraftwithconstant elevation angleof-lO°.(TheC-54isthe military versionofthefour-piston-engined DCAcommercial aircraftwithawingspan of36mandalengthof29m.)Eachpoint represents theaverage ofmedians obtained fromsamples withina10by10°aspectcell. 
 23. pp. 73-75. 
 IZED 8 
 One is near the cathode and is at cathode potential. (In the so-called Unig~-id,~~  this grid is pllysically placed on the cathode but is properly passivated to prevent emission.)  *l'lie second grid is the control grid for the beam current. It is at a positive potential arid is  locarcd ill tlie stladow of tile first grid. 
 TRACKING RADAR159 0.22- Figure5.6Plotoftherelativeangle­ errorsignalfromtheconical-scan radar asafunction oftargetangle(Or/Os) andsquintangle(O.,lOs). Os=half­ powerbeamwidth.{}q Antenna {}e crossover, dB 0.2 0.5 0.4 1.95 0.6 4.36 0.8 7.7 0.10.2 0.3 0.40.50.60.70.80.91.0 Br/Be0.04- 0.02 oL-----L_--L._.J-_..L..._-'----l_--'- __--I.-_-'-----'o0.06-S0.18 VI C11> .~0.16 C11 L ~0.1<1 o' C11 0"o ~0.12- > o .~0.10 VI Ie0.08 Lw0.20 anglebetween theantenna-beam axisandtheaxisofrotation; and88isthehalf-power beamwidth. Theantenna beamshapeisapproximated byagaussian function inthecalcula­ tionsleadingtoFig.5.6.Thegreatertheslopeoftheerrorsignal,themoreaccurate willbe thetracking ofthetarget.Themaximum slopeoccursforavalueOq/08slightlygreaterthan 0.4.Thiscorresponds toapointontheantenna pattern(theantenna crossover) about2dB downfromthepeak.Itistheoptimum crossover formaximizing theaccuracy ofangle tracking. 
 CEPTABLE LEVEL  THUS INCREASING SIGNIFICANTLY  THE PROBABILITY OF LOOSING A TARGET UNDER TRACK )T IS  THEREFORE  IMPORTANT THAT THE RADAR RECEIVER BE EQUIPPED WITH A #&!2 3INCE THE FALSE ALARM PROBABILITY IS RELATED TO THE DETECTION THRESHOLD  THE LATTER SHOULD BE ADAPTED ONLINE BASED ON THE INTENSITY OF DISTURBANCES 3ELECTION OF THE 7AVEFORM  4HE BENCHMARK  INCLUDES  WAVEFORMS  INDEXED BY  I  AND CHARACTERIZED BY A DIFFERENT PULSE WIDTH  SEI   SO THAT THE WAVEFORM CAN BE SELECTED  IN ORDER TO PROVIDE A 3.2 GREATER THAN THE DETECTION THRESHOLD AND THUS MAINTAIN AN ASSIGNED PROBABILITY OF TARGET DETECTION 4HIS CAN BE ACCOMPLISHED BY FIRST ESTIMATING THE AVERAGE TARGET  2#3 Ko AT TIME TK  AND THEN COMPUTING FOR EACH WAVEFORM  I  THE PRE 
 :!5,  pp. 121-124, January, 1954.  84. 
 Careful selection of the subgroup elements is necessary to avoid  grating lobes; this topic is discussed in a following section. Another simplification of  the fully adaptive array is the deterministic spatial filtering, where a fixed reduction  of the sidelobes is operated in those directions or solid angles from which the interfer - ences are expected to come. As an example, a probable region with interferences is  the horizon or part of it because jammers are mostly ground-based or at long range. 
 2.4. The average duration of a noise pulse is approximately  the reciprocal of the bandwidth B, which in the case of the envelope detector is BIF. Equating  Eqs. 
 The only function of the collector electrode in the  klystron is to dissipate heat. It can be ofa shape and size most suited for satisfying the average  or peak power requirements without regard for conducting RF currents, since none arc  prescnt.  The design flexibility available with the klystron is not present in other tube types con-  sidered in this chapter, except for the traveling-wave titbe. 
 POWER TUBES CANNOT USE A MODULATING ANODE BECAUSE THE CONTROL ELECTRODE  MIGHT NOT BE ABLE TO HANDLE THE POWER 7HEN THIS OCCURS  A HIGH 
 J. A,: The lnfli~ence of Atmospheric Conditioris'on Radar Performance, J. ltrst. 
 Lucero TR units in 1943. Radar Lucero Mk. I Lucero Mk. 
  AND A NEURAL NETWORK MODEL 4HE DATA CLEARLY SHOW THAT MEASUREMENT OF RADAR BACKSCATTER AT ONLY ONE ASPECT  ANGLE IS NOT SUFFICIENT TO DETERMINE WIND SPEED AND DIRECTION 4HE 3EASAT SCATTEROMETER USED TWO LOOK ANGLES SEPARATED BY  n   BUT THE RESULTING RETRIEVALS HAD AS MANY AS  &)'52%   4YPICAL BACKSCATTER STRENGTH VERTICAL AXIS  FROM A  WIND 
 :JJ.------, I  Transm,tled Tmnsrn1ss1on of  command dote to  radar for dwell N  Beam  steering......_  computer '---.._  calculoles "--- phase orders  for dwell N  Maximum Rodar return  !Julie, 1:,  Mo, range  dwell (N-1) full -data  from dwell  (N-1) , ' l / J  ., I  / I  I  ~  Tronsm,ss1on of  dato-dwe!l(N-1)  Pho se shit I er s  . sw!lched for  fransm1f  Pho5e shd ter s  sel for  > receive - dwell N  Rod or  transmit/ receive  operol1on ,. pulse range ... 
 37. Swerling, P.: Probability of Detection for Fluctuating Targets, IRE Trans., vol. IT-6, pp. 
 TO 
 ON FOR %UROPEAN WIND SCATTEROMETERS v  #ANADIAN * OF 2EMOTE 3ENSING   VOL     PP n    & - .ADERI  - ( &REILICH  AND $ ' ,ONG  h3PACEBORNE RADAR  MEASUREMENT OF WIND VELOCITY  OVER THE OCEANnn!N OVERVIEW OF THE .3#!4 SCATTEROMETER SYSTEM v  0ROCEEDINGS OF THE )%%%    VOL   PP n    # 7U  * 'RAF  - ( &REILICH  $ ' ,ONG  - 7 3PENCER  7 
 MEASURING SYSTEM  REPORTED VALUES ARE ALWAYS IN ERROR  BECAUSE  AS INDICATED ABOVE  IT IS ALMOST IMPOSSIBLE TO RESOLVE A NARROW RANGE OF ANGLES NEAR THE VERTICAL &OR SHORT RANGES  ONE CAN CONFIGURE THE ANTENNA SO THAT A PLANE WAVE IMPINGES ON THE SURFACE 7HEN THIS IS DONE  THE NEAR 
 M. D. Griffin and J. 
 Using a similar derivation,  Probert-Jones34 took this into account, assumed a gaussian shape for the antenna beam,  and derived the following equation for the received power:  PPG c rrt i iN = =∑2 2 2 2 15122 2λ θφ τ πσ( ln ) (19.11) where 2ln2 is the correction for the gaussian-shaped beam. By substituting Eqs. 19.3,  19.6, and 19.7 into Eq. 
 The amplified signal ispassed toVzwhere itisfurther amplified and fedback toVI.This regenerative action quickly lifts g, tothegrid-current point and drives gnfarpast cutoff sothat theoriginal condition isreversed. The plate ofVIisdown and that ofVzisatB+. 1W.H.Eccles andF.W.Jordan, Radio Rev.,1,143(1919).. 
 SIGHT  II  SEA 
 Nevertheless, the average effect ofmany triple corners istoprovide retrodirectivity intheradar target. Vertical and horizontal surfaces can combine into double (rather than triple) corners, giving directivity inelevation under certain con- ditions. Itwas shown inSec. 
 Forexample, assume theeventinquestion tobetheoutputvoltagevfromaradarreceiver. Uponobtaining this voltage, itisofinteresttodetermine whether theoutputwascausedbynoiseorbysignalinthe presence ofnoise.Theprobabilities ofobtaining noiseandsignal-plus-noise beforetheevent takesplacearetheaprioriprobabilities. Theyrepresent theinitialstateofknowledge concern~ ingtheevenJ..Theprobability thatthereceiveroutputvwascausedbynoiseorbysignal-plus­ noiseisanaposteriori probability andrepresents thestateofknowledge obtained asaresult ofobserving theoutput. 
 Once obtained, the ﬁrst left and ﬁrst right singular vectors can be used to deﬁne properly the reference functions to be used in the focusing procedure. Figure 2shows the plot of the elements of the diagonal matrix S. As the matrix Econtains 91. 
 If pulse compression is done prior to the A/D or if there is no pulse compression,  this limit is  I J B=20logτ τdB (2.48) where J is the timing jitter, t is transmitted pulse length, and Bt is the time-   bandwidth product. If pulse compression is done subsequent to the A/D converter,  then the limitation is  IJB=20logτ τdB (2.49) The limitations on the attainable MTI improvement factor are summarized in  Table 2.5. This discussion has assumed that the peak-to-peak values of these insta - bilities occur on a pulse-to-pulse basis, which is often the case in pulse-to-pulse  staggered MTI operation. 
 Singular value decomposition and least squares solutions. Numer. Math. 
 SHOT OR AVERAGE OF SNAPSHOTS BUT A NUMBER OF SNAPSHOTS OF THE ARRAY OUTPUTS THIS BLOCK OF DATA IS THEN USED TO CONSTRUCT WEIGHTS THAT ARE APPLIED TO THE BLOCK OF DATA BEFORE BEAMFORMING AND DOPPLER ANALYSIS 34!0 IS OF PARTICULAR IMPORTANCE TO SHIP DETECTION  WHERE THE EXTERNAL NOISE FIELD ALMOST INVARIABLY CHANGES SUBSTANTIALLY DURING THE LONG #)4 4HE COMPLEXITY OF 34!0 IN THIS CONTEXT ARISES FROM THE FACT THAT EACH TIME THE WEIGHTS ARE CHANGED ACCORDING TO THE 3!0 RULES  THE MAIN BEAM EXPERIENCES A PHASE SHIFT  EVEN THOUGH ITS AMPLITUDE GAINSENSITIVITY IS PRESERVED 4HUS  OVER THE ENTIRE #)4  A SEQUENCE OF PHASE SHIFTS IS APPLIED  THAT IS  A MODULATION  WHICH IS IMPOSED ON THE RECEIVED SIGNAL !S A CONSEQUENCE  THE STRONG CLUTTER ECHOES ARE SPREAD IN DOPPLER  MASKING TARGETS 4O OVERCOME THIS PROBLEM  !BRAMOVICH ET AL  DEVELOPED A TECH 
 The contours of constant doppler are perpendicular to  the x axis, and contours of constant range lie parallel to the x axis.  If the angle of target rotation over which the doppler is observed is too short, the doppler  spectrum is broad and the resolution is low. Increasing the observation time narrows the  spectrum and the resolution will increase. 
 K. Hocke and K. Schlegel, “A Review of atmospheric gravity waves and travelling ionospheric  disturbances: 1982–1995,” Annales Geophysicae , vol. 
 On this basis, the SAR image fusion is performed after image matching. The results of simulation and measured data conﬁrm the effectiveness of the system and the method. Keywords: SAR imaging; multi-angle SAR; improved RMA; SAR image fusion 1. 
 14.1 to compute the RCS. FIGURE 14.15  The method of moments divides the body surface into a collection of discrete patches. This  planform of the U.S. 
 R.. and M. C. 
 The exact result of this calculation depends on the assumed shape of the antenna  pattern; for this example, a sin()u u pattern terminated at the first nulls was assumed.  There is a comparable improvement factor degradation due to spectral spreading of  limited distributed clutter.34,35 Figures 2.64, 2.65, and 2.66  show the expected mean  improvement factor for two- three-, and four-pulse cancelers as a function of s/L,  the ratio of the rms clutter amplitude to the limit level. Hits per one-way half-power  beamwidth are indicated by N. 
 SEA  TEMPERATURE DIFFERENCE  OR THE PRESENCE OF LARGE WAVES SUCH AS OCEANIC SWELL  BUT THESE  ARE OF LESS SIGNIFICANCE FOR THE PRESENT DISCUSSION 4HE REFLECTION COEFFICIENT  R    IS NONLINEAR WITH RESPECT TO THE WIND PARAMETERS  &IGURE  ILLUSTRATES THE RESPONSE FOR ONE POLARIZATION  WHERE THE HORIZONTAL AXIS IS THE RELATIVE WIND DIRECTION  AND THE VERTICAL AXIS IS THE NORMALIZED RADAR CROSS SEC 
 TION  CERTAIN OTHER ASSUMPTIONS ARE A  4HE AIR IS DRY B  4HE AIR IS A PERFECT GAS  OBEYING THE ,AWS OF #HARLES AND "OYLEC  'RAVITY IS CONSTANT AT ALL ALTITUDESD  4HE TEMPERATURE OF THE ISOTHERMAL ATMOSPHERE IS  
 MINED BY THE RADAR ALTIMETERS POST 
 Luneburg lens.Workers inthefieldofopticshavefromtimetotimedevised lensesinwhich theindexofrefraction variedinsomeprescribed manner withinthelens.Although suchlenses hadinteresting properties, theywereonlyofacademic interest sinceopticalmaterials withthe required variation ofindexofrefraction werenotpractical. However, atmicrowave frequen­ ciesitispossible tocontrol theindexofrefraction ofmaterials (tlisthesquarerootofthe dielectric constant (),andlenseswithanonuniform indexofrefraction arepractical. Oneofthemostimportant ofthevariable-index-of-refraction lensesinthefieldofradaris thatduetoLuneburg.53TheLuneburg lensisspherically symmetric andhastheproperty that aplanewaveincident onthesphereisfocused toapointonthesurfaceatthediametrically opposite side.Likewise, atransmitting pointsourceonthesurfaceofthesphereisconverted to aplanewaveonpassingthrough thelens(Fig.7.21).Because ofthespherical symmetry ofthe lens,thefocusing property doesnotdependuponthedirection oftheincident wave.Thebeam maybescanned bypositioning asinglefeedanywhere onthesurfaceofthelensorbylocating manyfeedsalongthesurfaceofthesphereandswitching theradartransmitter orreceiver from onehorntoanother. 
 216, London, October 1982, pp. 188–192. 102. 
 The gating waveform is therefore  The above analysis indicates that optimum range processing consists in passing the ecllo  signal through a matched filter followed by a gating in time that samples the signal waveform  at the instant before and the instant following the time TR. The difference between these two  samples is a measure of the difference between the estimated delay time TR and the true delay  time To. In some respects, the gating process is analogous to the split-range-gate technique for  range-tracking radars described in Sec. 
 However, computer  software packages now exist that enable synthesis of arbitrary beam shapes via appli - cation of iterative optimization techniques in conjunction with physical optics–based  pattern computations. These analysis methods and software packages are summarized  in Section 12.5. Offset-fed parabolic reflectors are often used to mitigate feed blockage. 
 Applebaum, “Adaptive arrays,” IEEE Trans. Antennas and Propagation , vol. AP-24, no. 
 2.37 for the limitation on I due to scanning and staggering is obtained,  it is possible to determine the limitation on I due to internal-clutter motion and stag - gering. If  nn f fr vr v= × =1 2 201325( ).πλ σλ σ (2.38) (from Eqs. 2.14 and 2.15) is substituted into Eq. 
 VIEW &/6  VIA EITHER MECHANICAL OR ELECTRONIC MEANS OR SOME COM 
 33–38. 66. D. 
 STATE TRANSMITTER ! LOW DUTY CYCLE ENVIRONMENT IS NOT THE MOST COST 
 N., V. H. Rumsey, and T. 
 In Radar receivers as well as in the signal analysis circuitry,  vacuum tubes were replaced by semiconductors. Despite these improvements the technological development of Radar technology was slower than in the consumer goods industry until the 70’s.  The reason can be seen from the very long development phases needed for larger systems, pa r- ticularly in the military field. 
 2'0/ 4HE EXAMINATION OF THESE TABLES REVEALS THAT THE PRESENCE OF %#-S CONSIDERABLY DETERIORATES THE TRACKING PERFORMANCE IF NO APPROPRIATE %##-S ARE UNDERTAKEN #ONVERSELY  THE ADOPTION OF THE ABOVE DESCRIBED ! 
 The full scene had a limited number of trihedrals and dihedrals that imaged clearly. To analyze the scattering anisotropy of the targets, six vehicles, six trihedrals, three dihedrals, and a top-hat were selected manually, and their aspect entropies were calculated. The locations and aspect entropy with and without denoising of the targets are listed in Table 2. 
 bn = servo bandwidth Component Bias Noise Radar-dependent  tracking errorsZero range setting Range discriminator shift    servo unbalance Receiver delayReceiver thermal noise Multipath Servo electrical noise Servo mechanical noise Variation in receiver delay Radar-dependent  translation errors Range oscillator frequency Data takeoff zero settingRange resolver error Internal jitter Data gear nonlinearity and backlash Data takeoff nonlinearity and granularity Range oscillator instability Target-dependent  tracking errorsDynamic lag Beacon delayDynamic lag Glint Scintillation Beacon jitter Propagation error Average tropospheric refraction Irregularities in tropospheric refraction Average ionospheric refraction Irregularities in ionospheric refraction *From D. K. Barton in “Modern Radar,” R. 
 Resolution oftheSAR.Thebeamwidth ofaconventionalantenna ofwidthDatawavelength A.is 08=kl/D (14.2) wherekisaconstant thatdepends ontheshapeofthecurrentdistribution across~he aperture. (Theconstant kmightvaryfrom0.9to1.3orgreater.) Forconvenience ofanalysis, takek=1. Substituting Eq. 
 Askillful operator can allow for this effect and choose acourse onwhich thesignals, though notequal, do notchange relative tooneanother when thecourse isheld. This, regard- less ofsquint orcrabbing, isatrue intemeption course. The first radar beacons (Chap. 
 Univ. Min. T echnol. 
  
 The circulator does not provide  sufficient protection by itself and requires a receiver protector as in Fig. 9.9. The isolation  bet ween the transmitter and receiver ports of a circulator is seldom sufficient to protect the  receiver from damage. 
 40. Raven, R. S.: Requirements for Master Oscillators for Coherent Radar, Proc. 
 (ILL "OOK #OMPANY    ! ( 3CHOOLEY  h5PWIND 
 and can often last for several seconds.8 10 Spikes can give rise to excessive false  alarms in some radar applicatiPns. These spikes seem to he associated with breaking waves. 478 INTRODUCTION TO RADAR SYSTEMS  According to Long,9 about half the time the whitecap forms either simultaneously with  the appearance of a radar spike or a fraction of a second thereafter, leading to the conclusion  that the whitecap occurs after the radar spike develops. 
 The necessary phase relationships between the elements may be obtained with either a  series-fetl or a pnrczllel-fetl arrangement. In the series-fed arrangement, the energy may be  transmitted froni one end of the line (Fig. 8.4a), or it may be fed from the center out to each  end (Fig. 
 TINUES THROUGH FLIGHT TO A TARGET  AND ULTIMATELY RETURNS TO TH E STARTING POINT !LONG THE  WAY  THE AIRCRAFT USES A VARIETY OF MODES TO NAVIGATE  SEARCH AND ACQUIRE TARGETS  TRACK TARGETS  DELIVER WEAPONS  ASSESS BATTLE DAMAGE  ENGAGE IN COUNTERMEASURES  AND MONI 
 With  high power and a high gain antenna (52 dB) and special tracking techniques, they are  the workhorse for precision tracking of satellites and similar tasks. However, most  modern tasks require precision simultaneous tracking of multiple simultaneous targets  where use of multiple single target tracking radars are not cost effective. The develop - ment of electronic scan phased array technology has resulted in versatile high preci - sion monopulse tracking with the capability of simultaneous multitarget tracking by  switching its beam to each of several targets on a pulse-to-pulse basis or by groups  FIGURE 9.11  (a) RF phase-comparison mono - pulse system with sum and difference outputs and  (b) vector diagram of the sum and difference signals ch09.indd   12 12/15/07   6:07:14 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 CONTROLLED CONDITIONS 4HESE NEW  RESULTS LED TO THE FOLLOWING EXPONENTIAL MODEL FOR LAND CLUTTER SPECTRA   3F""F%80 LN  EXPLN  \\   
 H.: "Radars: New Concepts," Gordon and Breach, New York, 1968, sec. 4.6.  74. 
 MTI RADAR  2.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 and the corresponding signal-to-clutter improvement is  IT T T CSCRopt opt opt opt*=⋅ w s s w w w* * Φ (2.35) where the asterisk denotes complex conjugation and superscript T is the transposition  operator. An example where the optimum performance is determined for the case of  clutter at zero doppler having a gaussian-shaped spectrum with a normalized width  of sfT = 0.1 is shown in Figure 2.25. In this case, a coherent processing interval of   CPI = nine pulses was assumed, and the limitation due to thermal noise was ignored  by setting the clutter level at 100 dB above noise. 
 LOG     !II  B  WHERE !I AND PI ARE CONSTANTS THAT DIFFER FOR THE NEAR 
 This arrangement hasthedisadvantage that ittakes anumber oftubes and, like allmultistage feedback circuits, isdifficult toanalyze incase of trouble. Ithas theadvantage that, with small additional elaborations, thesample pulse residue after cancellation canbeused tocontrol thegain ofone channel ofthecomparison amplifier. This type ofAGC corrects forchanges inboth theamplifier and thedelay line. 
 D. Lynch, “Method and System for  Reducing Phase Error in a Phased Array Radar Beam Steering Controller, U.S. Patent 4,924,232,  5/8/1990. 
 440–443, 1985.  7. H. 
 For an air-traffic­ control radar these might include the following: purpose the radar is to serve; types of aircraft  it must detect; maximum range, with a stated probability of detection and average time  between false alarms; coverage; number of aircraft expected within the radar coverage; mini­ m um spacing of targets, which then determines the required resolution; accuracy of target  location, or the accuracy of the target trajectory if a track-while-scan radar; weather and the  environment in which the radar must operate, including restrictions imposed by the site or the . 538 INTRODUCTION TO RADAR SYSTEMS  t' •  . r... 
 Through the provision oflow-impedance ormultiple-output circuits for the sine and cosine voltages, asmany indicators asdesired can beused. The sweep length for each can bechosen independently ofthose ofthe others. 1Itisposeible, ofcourse, torelay the sweep components themselves. 
 BASED RADARS  IS TO SCAN IN A NORMAL SEARCH PATTERN  PAUSE ON EACH SEARCH DETECTION  AND ENTER A 3INGLE 
 After  the CFAR (which ideally would be identical in both channels), there are three thresh - olds: the main channel, guard channel, and main-to-guard-ratio thresholds. The detec - tion logic of these thresholds is also shown in Figure 4.10. The blanking that occurs because of the main/guard comparison affects the  detectability in the main channel, the extent of which is a function of the thresh - old settings. 
 The low-wind trace corresponds to a Rayleigh distribution; the  other segmented traces are two-parameter Weibull distributions defined by different  parameter pairs. It is clear that the behavior is different and considerably more com - plex than that shown in Figure 15.2 for higher grazing angles and wider pulses. From  the character of the data, Trizna interprets these three-segment traces as showing pri - marily receiver noise in the lowest branch, distributed (spatially homogeneous) clutter  in the middle branch, and genuine sea spikes in the branch containing the highest  cross sections, some of which exceed 1000 m2. 
 POLARIZED RESPONSE SHOWS ESSENTIALLY NO CROSS 
 112. Yu. I. 
 finding depends on a precise, unambiguous knowledge of the relative patterns of the (adapted) height finding beams. 20.2 DEB/VA TION OF HEIGHT FROM RADAR MEASUREMENTS Height in radar is always a derived rather than a measured quantity. This is true because a radar can only measure range and angle of arrival of target returns. 
 1958.pp.407-411. 51.Kummer. W.H.:FeedingandPhaseScanning, chap.Iin"Microwave Scanning Antennas, vol.III," R.C.Hansen(ed.).Academic Press.NewYork,1966. 
 ISAR is also widely used  for diagnostic measurements on indoor and outdoor radar cross section (RCS) ranges  (Knott et al.,26 p. 516). Improvements in SAR Resolution. 
 CINCT STATEMENT OF THE RELATIONSHIP BETWEEN ELECTRIC AND MAGNETIC FIELDS PRODUCED BY  CURRENTS AND CHARGES AND BY EACH OTHER 4HE FOUR EQUATIONS MAY BE MANIPULATED FOR  ISOTROPIC SOURCE 
 POLARIZATION FOR THE RADAR  AND 8 BAND CIRCULAR 
 Type of signal: Three types of signals are of general interest in determining dynamic-range requirements: distributed targets, point targets, and wideband- noise jamming. If the radar employs a phase-coded signal, the elements of the receiver preceding the decoder will not restrict the dynamic range of a point tar- get as severely as they will distributed clutter; the bandwidth-time product of the coded pulse indicates the added dynamic range that the decoder will extract from point targets. Conversely, if the radar incorporates an excessively wide- . 
 Meteoro. Soc. , vol. 
 TO 
 NAL TO DISCRIMINATE UNDER THE PREVAILING CLUTTER CONDITIONS )N LOW ATTENUATION MEDIA  THE RESOLUTION OBTAINED BY THE HORIZONTAL SCANNING TECHNIQUE IS DEGRADED  BUT ONLY UNDER THESE CONDITIONS DO SYNTHETIC APERTURE TECHNIQUES INCREASE THE PLAN RESOLUTION %SSENTIALLY THE GROUND ATTENUATION HAS THE EFFECT OF PLACING A hWINDOWv ACROSS THE 3!2 APERTURE  AND THE HIGHER THE ATTENUATION THE MORE SEVERE THE WINDOW (ENCE  IN HIGH ATTENUATION SOILS  3!2 TECHNIQUES MAY NOT PROVIDE ANY USEFUL IMPROVEMENT TO '02 SYSTEMS 3!2 TECHNIQUES HAVE BEEN APPLIED TO '02 BUT VERY OFTEN IN DRY SOILS WITH LOW ATTENUATION 3!2 TECHNIQUES TYPICALLY REQUIRE MEASUREMENTS MADE USING TRANSMITTER AND  RECEIVER PAIRS AT A NUMBER OF ANTENNA POSITIONS TO GENERATE A SYNTHETIC APERTURE OR TO FOCUS THE IMAGE 5NLIKE CONVENTIONAL RADARS  WHICH GENERALLY USE A SINGLE ANTENNA  MOST '02 SYSTEMS USE SEPARATE TRANSMIT AND RECEIVE ANTENNAS TO PROVIDE RECEIVER ISOLATION 4HE '02 COMMUNITY REFERS TO THIS AS A BISTATIC MODE  ALTHOUGH ACTUALLY THE ANTENNA SYSTEM IS CLOSELY SPACED AND MOBILE 4HIS IS DIFFERENT FROM THE TRADITIONAL RADAR COMMUNITY THAT ASSOCIATES THE TERM BISTATIC WITH LARGE SEPARATIONS Ó£°ÎÊ  " 
 6, pp. 939–941, June 2002. 22. 
 18.4.  6. R. 
 As with all imaging systems, SAR image products are rated according to their resolu - tion, where “higher” is “better.” Higher resolution always implies wider bandwidth in  both range and azimuth. Azimuth bandwidth derives from the doppler signatures set  up by the motion of the radar with respect to the illuminated field. Resolution by itself  is not sufficient to determine the image quality of importance to most applications. 
 25. Thomas Kazior (personal communication), Raytheon RF Components, August 2006. 26. 
 Rive. J.: Feed Support Blockage Loss in Parabolic Antennas, Microwace J., vol. 11. 
 Figure 8.1  Transmission types - Pulse Radar.       Figure 8.2  Transmitting and receiving signals with low PRF.  . 
 The homogeneous, solid, dielectric-lens antenna of Fig. 7.18a is similar to  the conventional optical lens. A point at the focus of the lens produces a plane wave on the  opposite side of the lens. 
 CALLY ACHIEVED BY COHERENT DEVICES  SO THAT THE CANCELLATION RESIDUE MAY STILL BE A SIG 
 Coaxisl Lines.-Coaxial lines consisting ofconcentric inner and outer conductors are not new. Atlower frequencies they have usually consisted ofcables with asolid dielectric and abraided outer ,IMicrmuaw Ma#ndrorz.s, Vol.6,Radiation Laboratory Series. aMicrowave Transrntision Circuits, Vol.9,Radiation Laboratory Series.. 
 Mouche, D. Hauser, and V . Kudryavstev, “Observations and modelling of the ocean radar  backscatter at C-band in HH- and VV-polarizations,” in Proceedings International Geoscience  and Remote Sensing Symposium , Seoul, Korea, IEEE, 2005. 
 (Thechemical recorder has beenofmoreuseinsonarthaninradar.)Theintegration improve­ mentwasfoundtobefrom2.2to2.5dBperdoubling ofthenumber ofpulses.whichis consistent withthecomputations forthetheoretical integration improvement obtained by Marcum43foridealpostdetection integration. Theresultsforthechemical recorder (curveA) areslightlybetterthantheB-scope (curveB)duetotheimperfect memory ofthecathode-ray tubeB-scope ascompared withthepermanent· memory ofthechemical recorder. Similar resultswerenotedfortheimprovement inaconventional PPIwhenthepulsesweredisplayed side-by-side. 
 OUT OF  RAD DURING THE TRANSMITTED PULSE WOULD THEN PLACE AN AVERAGE LIMITATION OF  D" ON THE IMPROVEMENT FACTOR ATTAINABLE 0ULSE 
 To achieve  high-power capacity, many such sections with small phase increments can be used so that  there are many diodes· to share the power. The ability to operate with high power is the  advantage claimed for this type of diode phase shifter. If the largest practical phase shift per  diode pair is )/16, or 22.5°, 32 diodes are required to shift the phase 360°. 
 IONIZED -EDIA v )NTERNATIONAL 4ELECOMMUNICATION 5NION  )NTERNATIONAL  2ADIO #ONSULTATIVE #OMMITTEE ##)2   VOL 6  2EPORT  
 Tech. Rept. 13, Contract DA-36-039 sc-15358, June, 1953. 
 As the antenna deviates from position S, the value of slant range error gradually increases. When the antenna is at S 1and S 2, the value of slant range error is the largest. We deﬁne the maximum slant range error as ΔRmax. 
 Delaytimesofthis magnitude cannotbe·achieved withpractical electromagnetic transmission lines.Byconvert­ ingtheelectromagnetic signaltoan'acoustic signalitispossible toutilizedelaylinesofa. MTI AND PULSE DOPPLER RADAR 107  reasonable physical length since the velocity of propagation of acoustic waves is about lo-'  that of electromagnetic waves. After the necessary delay is introduced by the acoustic line, the  signal is converted back to an electromagnetic signal for further processing. 
 1.2, each particular applica - tion of a radar generally has to employ a radar equation tailored to that specific applica - tion. When the radar echoes from land, sea, or weather clutter are greater than the receiver  noise, the radar equation has to be modified to account for clutter being the limitation to  ch01.indd   12 11/30/07   4:34:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Ksienski: Identification of Complex Geometrical Shapes by Means of Low­ Frequency Radar Returns, The Radio and Electronic Engineer, vol. 46, pp. 472-486, October, 1976. 
 ORITY  WHICH DROVE THE CHOICE OF POLARIZATION (ORIZONTAL WAS CHOSEN  BECAUSE THAT  p  )T IS COMMON IN RADAR REMOTE SENSING THAT THEIR POLARIZATIONS ARE ABBREVIATED AS AN ALPHABETIC PAIR  IN THIS CASE  INDICATING VERTICAL POLARIZATION ON BOTH TRANSMIT AND RECEIVE e  3PACE 
 21 25.  January. 1957. 
 J., A. C. Layton, and P. 
 The result is the limitation on I due to the oscillator noise. Rather than performing this integration of the residual noise numerically, a much  simpler analysis can be carried out if both the oscillator phase noise characteristic and  all of the adjustments to phase noise are approximated by straight lines on a decibel- versus-log frequency plot. This procedure becomes particularly simple when a MTI  FIR filter using binomial coefficients is assumed. 
 ch06.indd   1 12/17/07   2:02:53 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°ÈÇ  $ " #HELTON  * # 2IES  " * (AINES  , 
 l~-hen alinearly polarized radar wa~-e encounters theedges ofthesheets forming thestack, thecomponent \vhose electric Yector isnormal totheedge passes through unaffected. The component whose electric vector isparallel totheedge, however, finds itself inawaveguide ofgreat height butoffinite width, Itswavelength. SEC 3.11] EXTENDED SURFACE TARGETS 85 ward direction will becircularly polarized. 
          . 
 # HAS A MULTI 
 Among the single-chip circuit designs that have been reported from  UHF through millimeter-wave frequencies are power amplifiers, low-noise amplifi - ers, wideband amplifiers, phase shifters, attenuators, T/R switches, and other special  function designs. Noteworthy design considerations for these MMIC functions are  described next.FIGURE 11.17  Common T/R module configurations make use of power  amplifiers, low-noise amplifiers, duplexers, switches, and controls to enable on- face beam steering in a phased array antenna. Architecture variations may result  from component capability differences as well as performance and packaging  constraints. 
 The parameters of these TerraSAR-X images are listed in Table 2. In the processing of the two-pass di ﬀerential interferometry, a subset of 18 ×15 km was selected, covering about a quarter of the total area (see Figure 3a). SBAS processing was used to generate the unwrapped interferograms for the test area. 
 III in Sunderland Aircraft, CCDU Trial 43/45, August 1943 (TNA AIR 65/40) [11] ASV Mk. III in Sunderland (Second Report) —Production Installation, CCDU Trial Report 44/59, April 1944 (TNA AIR 65/126) [12] ASV Mk. IIIB, TRE Group 35 memorandum No. 
   9 4HERE IS A NEED FOR A QUANTITATIVE MEASUREMENT OF THE EFFICACY OF ONE OR MORE %##-  ELECTRONIC TECHNIQUES WHEN A RADAR EQUIPPED WITH THESE DEVICES IS SUBJECT TO AN %#- THREAT /NE PERFORMANCE MEASURE GENERALLY USED FOR AN UNJAMMED SEARCH RADAR IS THE DETECTION RANGE OF A CERTAIN TARGET AGAINST A SYSTEM NOISE BACK GROUND THIS SITUATION IS  REFERRED TO AS  DETECTION IN CLEAR ENVIRONMENT 7HEN THE RADAR IS JAMMED   IT IS OF INTER 
 Laminations between 0.001 and 0.005 in.thick are neces- sary tomaintain acore permeability ofseveral hundred uptothe fre- quencies ofseveral megacycles persecond present inasteep wave front. Special core materials forpulse transformers were developed during the war. Asquare voltage wave ofmagnitude VOand duration tapplied tothe inductance L.will build upacurrent ofapproximately IF=VO.t/L. 
 CALLY A COMPLEX FINITE IMPULSE RESPONSE &)2  FILTER DESCRIBED LATER  THAT ADJUSTS THE FREQUENCY RESPONSE OF EACH CHANNEL SO THAT ITS PASSBAND MATCHES THE OTHER CHANNELS IN PHASE AND AMPLITUDE BEFORE IT IS SUMMED WITH THE OTHER CHANNELS IN THE BEAMFORMER 4HE COEFFICIENTS OF THIS FILTER ARE DETERMINED THROUGH A CALIBRATION PROCESS $URING CALIBRATION  A TEST SIGNAL IS PRESENTED TO THE 2& INPUT OF ALL  CHANNELS 4HIS SIGNAL IS TYPI 
 cc ¯ 
 2013 ,28, 780–784. 44. Wang, Y.; Jun-Ling, W.U.; Wang, H.L.; Zhao, D.F. 
 315–323, 1999. 126. U. 
 'ERMAN  ENTERPRISE AIMED PRIMARILY AT ASSESSING AND MONITORING "RAZILS NATURAL RESOURCES !FTER SEVERAL YEARS OF TRADE STUDIES  , BAND WAS SELECTED   'HZ  4HE RADAR IS BUILT  AROUND A NEAR 
 The angular error l\O as  measured from the larger of the two targets is31  fi() a2 + a cos a  0 0 = 1 + a2 + 2a cos a. (5.2)  This is plotted in Fig. 5.13. 
 Each region can be designed to best perform its own  particular function independently of the others. For example, the cathode is outside the RF  field and need not be restricted to sizes small compared with a wavelength. Large cathode area  and large interelectrode spacings may be used to keep the emission current densities and  voltage gradients to reasonable values. 
 This is called flicker . 348 INTRODUCTION TO RADAR SYSTEMS  noise, or 1 /f noise. Above approximately 500 kHz, the noise-temperature ratio approaches a  constant value. 
 C. R. Mullin et al., “A numerical technique for the determination of the scattering cross sections  of infinite cylinders of arbitrary geometric cross section,” IEEE Trans ., vol. 
 141. S. H. 
 In the following discussion selected antenna designs are described to illustrate the state of the art in large antennas in space. United States Sp ace-Deploy able Antennas. A large space-deployable an- tenna that the United States deployed in space was the Lockheed-NASA ATS-6 parabolic reflector, launched in 1974. 
 I in 12 Hudsons, allocated to Nos. 224, 233 and 220 squadrons of Coastal Command. An understanding of the operational value of this new technology was also still beingdeveloped. 
 This geometry gives the maximum RCS for the rod. The upper scale of the abscissa gives the one-half-wavelength dimension of the frequency given on the lower scale. The curve marked 90° is the RCS of the oblong-shaped conducting body of 11-m length and 1-m thickness; again the tar- get long dimension is aligned with the electric field. 
 The  two inputs to the multiplier are the received echo signal y(t) and a gating signal g(t - TR). The  time TR = 2Rlc is the estimate of the true delay time To. The purpose of the gating signal is to  aid in extracting an esimate of To. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 23.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 53. 
 At this point the energy appears  at botli crids of tile aperture ar~d two beams are found in the secondary pattern. The antenna  Figure 7.17 Principle of the organ-pipe  scanner.  RADAR ANTENNAS 247 Theadvantage oftheparabolic torusisthatitprovides aneconomical methodforrapidly scanning thebeamof aphysically largeantenna aperture over.arelatively widescananglewith 110deterioration ofthepatternoverthisangleofscan.Itsdisadvantages areitsrelatively large physical sizewhencompared withothermeansforscanning andthelargesidelobes obtained inintermediate planes. 
 Ideal mixers in a superheterodyne receiver act as multipliers, producing an output  proportional to the product of the two input signals. Except for the effect of nonlineari - ties and unbalance, these mixers produce only two output frequencies, equal to the sum  and the difference of the two input frequencies. The nonlinearities and imbalance of  mixers is described in more detail in Section 6.4. 
 Thetransmitting antenna provides asinglebeamilluminating thecoverage oftheNreceiving beams.Asdescribed in Sec.R.2.inordertogenerate abeamatsomeangle00,theremustbearelativephasedilTerence hetween adjacent elements equalto¢=21t(dIA.}sin00,Iftheleft-hand element ofanN­ element lineararrayistakenasthereference, thenthephaseshiftersattheotherelements must havevaluesofcp,2cp•...,(N-I)¢.Ifthebeamisscanned asafunction oftime,thesephase shiftsalsochange asafunction oftime.Aconstant rateofchangeofphasewithtimeis equivalent toaconstant frequency. Thusafrequency difference atadjacent elements resultsin ascanning heam.IftheLOsinthemixersofFig.8.29differinfrequency by!"thebeam repetitively scansitscoverage atarateof!,.Thatis,theantenna beamoccupies allpossible scanpositions duringthescantime1/.(,.Another wayoflooking atthisistonotethatifthe relative phasebetween adjacent elements ofanarrayischanged by21tradians, theradiation patternwillassumeallpossible scanpositions. Ifthe21tradiansischanged inatimeIlfs'thenthe raleofchange ofphaseis2rr.f.,.Thusthelinearphasechange canbeaccomplished if thefrequency difference between theLOsatthemixersofadjacent elements isIs' Bymultiplying thesummed outputofalltheelement mixerswithaperiodic sampling trainofnarrowgatingpulses,aparticular portionofspaceisobserved. 
 center(apex)oftheparaboloid. Ther~isedsurfaceismadeofsuchasizeanddistance from theoriginal reflector contour astoproduceatthefocusareflected signalequalinamplitude butopposite inphasetothesignalreflected fromtheremainder ofthereflector. Thetwo reflected signalscancelatthefeed,sothatthereisnomismatch. 
 PELLER REVMIN AND NUMBER OF BLADES 3INCE IT IS NOT USUALLY SINUSOIDAL  THERE ARE HARMONIC FREQUENCIES SPREAD THROUGHOUT THE SPECTRUM  AS SHOWN IN &IGURE  FOR THE 3."  A SMALL AIRCRAFT WITH TWO PROPELLER ENGINES 4HE LOCATION OF THESE SPIKES IS NOT DEPENDENT ON 2& FREQUENCY  AS IN THE CASE OF LOW 
 Theoretically there are no spurious signals generated by internal reflections in a  matched feed. It is not always convenient, however, to use four-port junctions. Three-port tee  junctions are sometimes used for economic reasons to provide the power splitting, hut the  network is not theoretically matched. 
 STAGE 'A!S --)# POWER AMPLIFIER WITH INSERT  SHOWING MULTIPLE PARALLELED GATE FINGERS IN FINAL STAGE UNIT CELL  0HOTOGRAPH  COURTESY OF 2AYTHEON #OMPANY  . 
 IT-1, pp. 1–9, March 1955. 16. 
 WAVE STRUCTURE IS THE RING 
 ( b) Percentage error for aspect entropy calculation in different SNR. We proposed a denoising method for the RCS curve and Figure 6is the diagram of the whole procedure. The RCS curve of dihedral B with SNR =20dBis used as an example. 
 BASED CASE /NLY MONOSTATIC RADARS WILL BE CONSIDERED 02&S 0ULSED RADARS THAT EMPLOY DOPPLER ARE DIVIDED INTO THREE BROAD 02& CAT 
 The authors propose an approach based on the least squares of compressed sensing residuals, which is used in video imaging and does not require the isotropic scattering assumption adopted by other methods. This procedure is able to reconstruct time sequences of sparse signals changing slowly with time, and thus it is well suited to processing images derived from SAR sub-apertures, which are highly overlapped. The proposed approach was tested on real data, providing a more accurate estimation of aspect dependent scattering than other methods based on compressed sensing. 
 If the first blind speed were 600 knots, the maximum unambiguous  range would be 130 nautical miles at a frequency of 300 MHz (UHF), 13 nautical miles at  3000 MHz (S band), and 4 nautical miles at 10,000 MHz (X band). Since commercial jet  aircraft have speeds of the order of 600 knots, and military aircraft even higher, blind speeds in  the MTI radar can be a serious limitation, .. ,  In practice, long-range MTI radars that operate in the region of Lor S band or higher and  are primarily designed for the detection of aircraft must usually operate with ambiguous  doppler and blind speeds if they are to operate with unambiguous range. 
 M  M..... ...... TO SIGNAL  PROCESSOROUTPUTS ARE CALLED   "RANGE BINS" • Gates are opened and closed sequentially  • The time each gate is closed corresponds to          a range increment  • Gates must cover the entire interpulse period          or the ranges of interest  • For tracking a target a single gate can remain          closed until the target leaves the bin. 
 Agivenchangeinfrequency withanarrow-spectrum pulsewillbe noticedmorethanwithawidespectrum pulse. Theeffectoftheloadonthemagnetron characteristics isshownbytheRiekediagram, whosecoordinates aretheloadconductance andsusceptance (orresistance andreactance). PlottedontheRiekediagram arecontours ofconstant powerandconstant frequency. 
 81static radar cross sections for  various-shaped objects have been reported in the literature.60 68 Two cases of bistatic radar  cross section will be considered. In one the scattering angle fJ (defined in Fig. 14.12) is exactly  equal lo 1800. 
 TO 
 Borkowski, and G. Jerinic, “Transmit/receive modules,” IEEE Transactions on  Microwave Theory and Techniques , vol. 50, no. 
 The process continues onsuccessive cycles until thedelay issuch that thesine pulse” straddles” theinstant of switching. The delay circuit will then follow thevariations inthedelay ofthesine pulse sothat the output voltage varies inthedesired manner. Figure 17.14 illustrates asystem inwhich, although itisassumed that the modulator can betriggered, means are provided todistinguish between thecosine pulse and themodulator pulse forother reasons. 
 CATIONS REQUIRING SCANNING OR MULTIPLE BEAMS OVER VERY WIDE ANGLES )TS DESIGN IS BASED UPON THE FACT THAT  OVER LIMITED ANGULAR REGIONS  A SPHERICAL SURFACE VIEWED FROM ANY POINT HALFWAY BETWEEN THE CENTER OF A SPHERE AND ITS SURFACE IS NEARLY PARABOLIC 4HIS MEANS THAT IF A FEED IS MOVED ALONG AN INNER SPHERICAL SURFACE OF CONSTANT RADIUS  2   WHERE 2 IS THE RADIUS OF THE SPHERICAL REFLECTOR  THE SECONDARY BEAM CAN BE STEERED 4HE  RANGE OF BEAM STEERING IS LIMITED BY THE SIZE OF THE SPHERICAL REFLECTOR  IE  THE PORTION OF A FULL SPHERE REALIZED BY THE REFLECTOR 4HE SCANNING CAPABILITY CAN BE IMPLEMENTED VIA USE OF EITHER A SINGLE MOVABLE FEED OR AN ARRAY WITH SWITCHABLE FEEDS 3ELF 
  n    n n  n  n E 
 (23.19), R0 is the surface rainfall rate, h is the height above the earth's surface, and d is a constant, equal to about 0.2. Convective-type precipitation, however, shows a quite different nature. The presence of the virga (precipitation aloft but evaporating before reaching the sur- face) associated with so many shower-type clouds indicates that Eq. 
 Radar for VTS is separately covered in Section 22.10. The challenges facing designers of shipborne radar are detailed within Section 22.2.  These radars have to meet certain international standards, which are discussed in  Section 22.3. 
 Two of these in a  mixer-matrix array can provide steering in two angular coordinates. One delay line at  frequency f1 might be used to obtain the elevation steering and a second line at frequencyf 2  might obtain the azimuth steering. The output of the mixer at each element is taken at the sum  frequency. 
 or ECCM.  The several forms of ECM directed against radar may be categorized as noise jamming,  deception jamming, cl~afl; and decoys. Intercept receivers and direction finders (which are  called tlluc-trorlic- strpport nrpustrres, or ESM), as well as antiradiation missiles (ARM) are also  aspects of e/ectrotlic wurJUr~ (EW) that must be of concern to the military radar systenls  designer. 
 60, pp. 735 -736, June,  1972.  41. 
 14.Cady.W.M.,M.B.Karelitz. andL.A.Turner (eds.):"Radar Scanners andRadomes," MIT Radiation Laboratory Series.vol.26,McGraw-Hili BookCompany, NewYork,1948. 15.Pugh,S.,andD.E.Walker: Reflector Surfaces forCommunications andRadarAerials," Designand Construction ofLargeSteerable Aerials," Il1stitlltioll ofElectrical Engineers (London) lEECOI!ference PlIhlicatimt no.21.pp.369-373, 1966. 
 J. K. Mulcahey and M. 
 One  can derive improved rainfall rates (as well as other physical information on the type of  precipitation) as functions of polarimetric measurements that relate the differences in  the horizontally and vertically polarized signals. By far the most common polarimet - ric parameters are the “differential reflectivity” ( Zdr) and “differential phase” ( Φdp),  which give bulk scattering and propagation characteristics of the meteorological tar - gets. Letting Eh and Ev denote the complex received signal voltages  that also repre - sent the received electric fields  at horizontal and vertical polarizations, the important  polarimetric parameters to be estimated are given below11:  Differential reflectivity Zdr = <Zh > / < Zv> (19.28)  Differential phase Φdp = <Φv > − <Φh> (19.29)  Specific differential phase Kdp = d<Φdp> / dr (19.30)  Co-polar correlation ratio rhv = |< Eh*Ev > | / < E*hEh>½ <E*vEv>½ (19.31)  Linear depolarization ratio LDR = <Zcx v> / < Zco h> (19.32) Zh and Zv are the measured reflectivities of the horizontal and vertical co-polar - ized received signals and Zdr is expressed in dB, whereas Φh and Φv are the measured  phases of the same polarized received signals. 
 Other image processing methods like noise reduction and adaptive thresholding were used to improve object extraction in the proposed methodology. Results demonstrated the ability of the techniques to reduce false positives by up to 60% in the provided SAR image pairs. However, there is still room for further improvement. 
 It was noted [ 3] that the design of these turrets caused considerable dif ﬁculty, especially the moving contacts. The Mk. II transmitter used one turret, of the same design, with four pre-set condensers. 
 Root, and J. F. Thomason, “RADARC model comparisons with Amchitka  radar data,” Radio Science , vol. 
 18Minimum Detection Range • The minimum received power that the radar receiver can "sense"  is referred to a the minimum detectable signal (MDS) and is  denoted          . • Given the MDS, the maximum detection range can be obtained:   Smin RPr Pr∝1/R4 RmaxSmin Pr=Smin=PtGtGrσλ2 (4π)3R4⇒Rmax=PtGtGrσλ2 (4π)3Smin⎛  ⎝ ⎜ ⎞  ⎠ ⎟ 1/4. 19Radar Block Diagram • This receiver is a superheterodyne receiver because of the intermediate    frequency (IF) amplifier. 
                     .   2!$!2 $)')4!, 3)'.!, 02/#%33).'   Óx°£Î &)2 FILTERS ARE DESCRIBED IN 3ECTION    WHERE THE TOP AND BOTTOM FILTERS APPLY THE  REAL AND IMAGINARY PARTS OF THE COEFFICIENTS  RESPECTIVELY 4HE EQUIVALENT COMPLEX 
  AND NEGATIVE 
 Because these tend to be small effects, it is not easy to isolate and char - acterize them. Creeping Waves.  A creeping wave is one that gets bound to a smooth, shaded sur - face, is guided around the rear of a smooth body, and is then launched back to the radar  when it reappears at the shadow boundary on the opposite side. 
 The wide-angle scanning capability of a lens would be of interest in radar as a competitor  for a phased array if there were available a practical means for electronically switching the  transmitter and receiver among fixed feeds so as to achieve a rapidly scanning beam.  7.6 PATTERN SY NTHESlS  The problem of pattern synthesis in antenna design is to find the proper distribution of current  across a finite-width aperture so as to produce a radiation pattern which approximates the  desired pattern under some condition of optimization. Pattern-synthesis methods may be  divided into two classes, depending upon whether the aperture is continuous or an array. 
 TO 
 F. Kretschmer, Jr.: A New Class of Polyphase Pulse Compression Codes and Techniques, IEEE Trans., vol. AES-17, pp. 
 The l~lIctua­ tionswidenthespectrum bymodulating theechosignal.Inaparticular case,ithasbeen reported12thattheaircraftcrosssectioncanchangeby15dBforachangeintargetaspectof aslittleas~o.Theechosignalfromapropeller-driven aircraftcanalsocontainmodulation components atafrequency proportional tothepropeller rotation.lsThespectrum produced bypropeller modulations ismorelikethatproduced byasine-wave signalanditsharmonics ratherthanabroad,white-noise spectrum. Thefrequency rangeofpropeller modulation depends upontheshaft-rotation speedandthenumberofpropeller blades.Itisusuallyinthe vicinityof50to60HzforWorldWarIIaircraftengines. Thiscouldbeapotential sourceof dirficulty inaCWradarsinceitmightmaskthetarget'sdoppler signaloritmightcausean erroneous measurement ofdoppler frequency. 
 AES-16, pp. 393-397, May 1980. 32. 
 It could also mean that a vessel’s AIS is not operating or is transmitting  erroneous positional information. If only AIS data is received, the radar image may  be obscured by clutter, a headland, or even a poorly setup or faulty radar installation.  Normally, just a few targets will be uncorrelated, highlighting that these few should  be given additional caution if they are significant to own-ship navigation, at least until  they can be positively identified, perhaps visually. 
 1577–79, November 9, 1989. 31. W-D. 
 6.15 Patterns for off-axis feeds. creases with the angular displacement in beamwidths and decreases with an in- crease in the focal length. Figure 6.15 shows the effect of this distortion on the pattern of a typical dish as a feed is moved off axis. 
 It can be used for target discrimination as man-made targets are usually anisotropic, while natural targets are usually isotropic. Additionally, different types of targets usually have varying degrees of anisotropy. Because anisotropic behavior has many uses, it has been widely studied in recent years [ 8–10]. 
 Franklin Medal awarded to B. Widrow for pioneering work on adaptive signal  processing. 92. 
 The  function of the diode is to hold the maximum voltage and keep the delay line from discharging  until the thyratron is triggered.26 Although the series diode is a convenient method for varying  the prf, it is more difficult to change the pulse width since high-voltage switches in the ..  pulse-forming network are required.  The bypass diode and the inductance L8 connected in parallel with the thyratron serve to  dissipate any charge remaining in the capacitance due to tube mismatch. 
 The simulations on both point and extended target indicate that the scintillation-induced azimuth degeneration becomes more serious with the increasing of scintillation strength and spectral index. The Monte-Carlo simulation shows that the scintillation effect will be insigniﬁcant in the case of CkL≤1032and p≤2 which can be considered to be a threshold. Since the ReBP algorithm also accommodates to TOPS and ScanSAR modes, the SAR-SS proposedin this paper can also be used to analyze the scintillation effect for these multi-mode SAR systems working in L-band or P-band. 
 PATH FACTOR  .   NOISE POWER PER UNIT BANDWIDTH  ,P  ,S   TRANSMISSION 
 VOLTAGE SUPPLY USES FEWER NONSTANDARD PARTS AND IS GENERALLY LESS EXPENSIVE L 4RANSMITTERS DESIGNED WITH SOLID 
 Radars designed for studies of nonprecipitating clouds may use short wavelengths35'36 (8 mm or even 3 mm) in order to achieve sufficient sensitivity to detect small cloud particles of the order of 100 |xm and smaller. And FM-CW radars37 have been used to obtain very- high-range resolution for detection of very thin layers in the clear air. However, most meteorological radars are conventional pulsed or pulsed doppler systems. 
 ·  62. Lin, Y.-T., and A. A. 
 Swerling: Adaptive Arrays, Microware J., vol. 17. pp. 
 Farina and L. Timmoneri, “Cancellation of clutter and e.m. interference with STAP algorithm. 
 Lett. 2016 ,13, 247–251. [ CrossRef ] 22. 
 8. M. I. 
 CONTROLLED TUBE IS CALLED A  #OAXITRON  )N ONE EMBODI 
 In addition, sea clutter exhibits  both current and wind-driven motion as well as “spiky” behavior. These facts often  require high resolution and multiple looks in frequency or time to allow smoothing of  sea clutter for stable detection and track.16,45 If the target is a significant surface ves - sel, then RCS might be 1000 m2, and a 30 m range resolution might be used for search  FIGURE 5.27  TF/TA terrain merging7,8,8 7 (Courtesy SciTech Publishing ) ch05.indd   30 12/17/07   1:27:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The amplitude of  each point in the output signal is a measure of how well the filter kernel matches the  corresponding section of the input signal. The output of a matched filter does not nec - essarily look like the signal being detected, but if a matched filter is used, the shape  of the target signal must already be known. The matched filter is optimal in the sense FIGURE 21.15  GPR Soil Suitability Map of the Continental (Conterminous) United States ( Courtesy  of USDA-NRCS ) ch21.indd   20 12/17/07   2:51:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 FREQUENCY PRECIPITATION RADAR IS THE ACTIVE MICROWAVE INSTRU 
 M. Headrick: Ionospheric Effects on HF Over-The-Horizon Ra- dar, in Goodman, J. M. 
 April. 1953.  Ih. 
 ANGLES  IT IS STANDARD  PRACTICE TO INSTALL A GROUND MESH SCREEN THIS HAS THE  SECONDARY BENEFIT OF AVOIDING PATTERN DISTORTION DUE TO INHOMOGENEITIES IN THE SOIL &OR  EXAMPLE  THE *INDALEE TRANSMIT ARRAYS SIT  ON ^  HECTARES ^   ACRES  OF STEEL MESH   EXTENDING ^  M IN FRONT OF THE ARRAYS .OTWITHSTANDING THE MERITS OF VERTICAL DIRECTIVITY  MOST SKYWAVE RADARS DO NOT  EMPLOY STEERABLE DIRECTIVITY IN ELEVATION BUT COVER ALL NECESSARY RADIATION ANGLES WITH ONE BROAD ELEVATION BEAM 4HIS CHOICE PERMITS THE ANTENNA TO HA VE A RELATIVELY SMALL  VERTICAL DIMENSION  AND HENCE REDUCED COST  THOUGH DEMANDS ON ANTENNA RADIATION EFFICIENCY IMPOSE A LOWER LIMIT !NOTHER ISSUE IS THE CHOICE OF TRANSMIT POLARIZATION .EARLY ALL OPERATIONAL SKYWAVE  RADARS RADIATE WITH VERTICAL POLARIZATION  BASED ON THE EASE OF ACHIEVING GOOD VERTI 
 Reindl, “Wideband compressive receiver with SAW convolver,”  1995 IEEE Ultrasonics Symposium , pp. 155–158. 13. 
 paraboloidA Elevation // handwheel AA Horizontal shaft’ and yoke A’I-Azimuth scale E. Le”e,“(a, ir-- Vetficalshaftand ,drivemotorassembly —Azimuth handwheel .. ‘4s“L1:1~.5,6.—Rear view of10-cnl doppler system. 
 1, p. 488). The antenna impedance  also changes with a change ill feed position. 
 The range in Eq. (13.8) appears as the first power ratller than as tllc  fourth power in the usual radar equation of Eq. (13.6). 
 As an example of the effects of high resolution on land clutter, measurements have been  reported with a horizontally polarized C-band radar having a 15-11s pulse width (3 m resolu-  tion) and a 1.5" beam~idth.~~ A rural region in England consisting of woods, fields, buildings,  villages, small towns, and structures such as pylons, was examined at ranges from 7 to 11 km.  It was found that 65 percent of the clutter exceeded 0.1 mZ, 18 percent exceeded 1 m2, and less  than 1 percent exceeded 10 m2. The clutter with radar cross sections greater than 10 mZ was  limited to 6 m in length and was found to be associated with man-made objects such as  electricity pylons and buildings. 
 Kester, The Data Conversion Handbook , London: Elsevier/Newnes, 2005. 11. R. 
 This section briefly summarizes how a radar systems engineer  might begin to approach the conceptual design of a new radar. There are no firmly  established procedures to carry out a conceptual design. Every radar company and  every radar design engineer develops his or her own style. 
 Case 1 is  where the radar and target speeds are equal and the target can be seen clear of sidelobe  clutter in a head-on aspect out to 60° on either side of the target’s velocity vector.  Similarly, Cases 2 through 4 show conditions where the target’s speed is 0.8, 0.6, and  0.4 times the radar’s speed, in which case the target can be seen clear of sidelobe clut - ter over a region of up to ±78.5° relative to the target’s velocity vector. Again, these  conditions are for an assumed collision course. 
 ................................ ................................ ............................ 
 season, time of day, and the wind speed. In the North Sea the mean duct thickness is  about 6 m while in tropical regions it is of the order 10 to 15 m.34 In the North Atlantic at  Weather Ship D (44"N, 41°W) the median value ofduct thickness (half the ducts have thickness  of lesser value) is I0 m in the summer and 30 m in the winter.35 In the area offshore of San Diego,  the medium value of the duct thickness as calculated from 5 years of meteorological data is  6 rtl. and a similar calct~latio~i for the Mediterranean Sea is 10 m.36 Measurements made in the  Atla~itic tradewind area ofT of Antigua showed ducts averaging 6 to 15 m in height.j7 Tlie  PROPAGATION OFRADAR WAVES453 Elel'ated ducts.Anexample ofpropagation inelevated ductsisfoundinthc..tradcwind region" between themidocean. 
 4(% 
 The azi- muthal shear is given by Av/AJC = 2vr/ra. velocity with azimuth angle as shown in Fig. 23.3. 
  MEASURING DEVICES %VERY PURE AND APPLIED SCIENCE THAT USES AERIAL PHOTOGRAPHY CAN ALSO USE RADAR  IMAGES 4HIS IS PARTICULARLY USEFUL IN CLOUDY ENVIRONMENTS  BUT RADAR IS ALSO USEFUL EVEN IN CLEAR WEATHER BECAUSE PERFORMANCE IS INDEPENDENT OF TIME OF DAY SO SUN ANGLE DOES NOT MATTER -OREOVER  RADAR GROUND SIGNATURES DIFFER FROM THOSE IN THE VISIBLE AND INFRARED 2ADAR HAS BEEN APPLIED TO AGRICULTURE  FORESTRY  GEOLOGY  HYDROLOGY  URBAN GEOGRAPHY  REGIONAL STUDIES  OCEANOGRAPHY  AND ICE MAPPING &ADING COMPLICATES THE INTERPRETATION OF IMAGES BY PRODUCING  SPECKLE 4HIS MEANS  THAT AVERAGING OF THE SPECKLED IMAGE USUALLY IS NECESSARY 3OMETIMES THE PROCESSOR DOES THE AVERAGING  AND SOMETIMES THE INTERPRETER DOES IT MENTALLY IT MUST BE DONE TO INTERPRET AN IMAGE 4HE IMAGE INTENSITY FOR INDIVIDUAL PIXELS WITH A SINGLE 
 SPEED DEPENDENCE OF SEA  CLUTTER CURVED TRACES  COMPARED WITH VARIOUS POWER LAWS STRAIGHT  LINES  DERIVED FROM 7 * 0IERSON AND - ! $ONELAN Ú !MERICAN  'EOPHYSICAL 5NION   &)'52%   3EA CLUTTER FROM A TOWER PLATFORM WITH POWER 
 Glint reduction. In a tracking radar, the angle and range errors introduced by a finite size target  are reduced with increased range-resolution since it permits individual scattering centers  to be resolved.  Multipatlt resolution. 
 CS Debiased-CS LS-CS-Residual 22.31 23.43 20.08 33. Sensors 2019 ,19, 490  
 The assumption of hazardous nonthermal effects at low densities of radiation is a fear that has  not been ~ubstantiated.~' The demonstration of a biological effect due to microwaves does not  of necessity demonstrate a peril. Confusion also can result at times between microwaves and  other more harmful radiations. Microwave radiation is nonionizing and is vastly different Y'  from ionizing radiations such as X rays. 
 P. Ekelman and B. S. 
 12.1 1. An  ambient temperature of 260 K is' assumed in the computation of atmospheric-absorption  noise. At the higher frequencies (X band or above) atmospheric absorption is the predominant  contributor to the brightness tem+rature, while at the lower frequencies (L band or lower),  the cosmic noise predominates.' There'exids a broad minimum in the brightness temperature  extending from about 1,000 to 10,000 MHz. 
 Óä°Ón  2!$!2 (!.$"//+  4HE CURVES MARKED     AND n GIVE THE 2#3 AS THE TARGET IS ROTATED TO THESE  ANGLES IN THE PLANE THAT CONTAINS THE ELECTRIC VECTOR 4HE LITTLE SKETCHES GIVE  AT THE LEFT   THE BODY SHAPE  AND THEN THE 2#3 PATTERNS AT NOMINAL  WAVELENGTH   WAVELENGTH  AND  WAVELENGTH  IN ORDER TO HELP VISUALIZE HOW THE 2#3 WILL CHANGE AS THE ASPECT ANGLE IS VARIED &OR TARGETS OF OTHER LENGTHS WITH APPROXIMATELY THE SAME SHAPE FACTOR  THE RESPONSE CAN BE DETERMINED BY SLIDING THE CURVE ALONG THE  L LINE AND MAKING THE  FIRST RESONANCE COINCIDE WITH THE LINE AT THE  WAVELENGTH POINT !S HAS BEEN MEN 
 With a ground-based radar the attenuation is greatest when the antenna points to  the horirnn. and it is least when it points to the zenith. Figure 12.10 gives examples of  the two-way attenuation for elevation angles of O and 5°. 
 However. the larger the dielectric constant, the greater will be the mismatch  between the lens and free space and the greater the loss in energy due to renections at the  surface of the lens. Compromise values of the index of refraction lie between 1.5 and 1.6. 
 COVERED GRASSLAND SIMILAR TO THAT FOR VEGETATION  DEPENDS ON A MORE LIMITED DATA SET  4HE DATA WAS FOR ONLY ONE SEASON IN #OLORADO  WHEN THE SNOW WAS ONLY ABOUT  CM DEEP 4HIS MEANS THAT THE SIGNAL PROBABLY PENE 
 E., J. D. Mallett, and I. 
 Electronics.) altitude-return spectrum willdepend uponthevariation ofthecluttercrosssectionasa function ofantenna depression angle.Thecrosssectionoftheclutterdirectly beneath the aircraftforadepression angleof90°canbequitelargecompared withthatatsmalldepression angles.Thelargecrosssectionandthecloserangecanresultinconsiderable altitude return. Theclutterilluminated bytheantenna sidelobes indirections otherthandirectlybeneath theaircraftmayhaveanyrelativevelocity from+vto-v,depending ontheanglemadeby theantenna beamandtheaircraftvectorvelocity(vistheaircraftvelocity). Theclutter spectrum contributed bythesesidelobes willextend2v/A.Hzoneithersideofthetransmitter frequency. 
 Directive gain. A measure of the ability of an antc~lr~ii to cor~ccrltratc clicrgy in a partictrlar  direction is called the gain. Two different, but related definitions of antenna gain are tile  directive gain and the power gain. 
 7.1 CW Doppler Radar   7.1.1  The Doppler Frequency   The Doppler effect is caused by a relative movement between Radar and reflecting objects,  identical to acoustics when there is a velocity difference between hearer and  the sound source  (police car).  The Doppler Frequency ωD is calculated from:   Dω=2πDf=dΘ dt=2π λdr dt=4πrv λ (7.1)  Df=r2v λ≈55,5•rv(km /h) λ(cm)(Hz)  (7.2a)  Df=T1,85f(GHz )rv(km /h)(Hz) (7.2b)  where  € λ is the wavelength and  € vr is the radial ve locity.  Figure 7.1 shows a simple CW Radar  schematic. 
 H e earn ed th e Doctor of Engineering Degree from The Johns Hopkins University, where he also received the B.E and M.S.E degrees inelectrical engineering. He is a member of the U.S. National Academy of Engineering, a Fellow of the IEEE,and the first recipient of the IEEE Dennis J. 
 In PN, the rate of rotation of the LOS is measured, and a lateral acceleration of the missile is commanded according to the equation nL = N'VC\ where nL - lateral acceleration N' = effective navigation ratio (constant, selected as discussed below) Vc = closing velocity \ = rate of change of the line of sight The lateral acceleration ideally should be normal to the LOS; in practice the de- flection of the missile control surfaces will result in acceleration normal to the missile velocity vector. The closing velocity can be estimated or, in the case of a doppler radar, measured (the target doppler is an approximate measure of Fc, as noted above). The LOS rate X is measured by the seeker—this is the seeker's primary func- tion. 
 71–1072, Palo Alto, CA, November 8–10, 1971. 84. H. 
 The model is based on the equation for the voltage at the receiver  as a function of range r and target radar cross-section s and given by reference  Rutledge and Muha.30 In the first model shown in Figure 21.7, the antenna is set at a height of 15 cm above  the target (dielectric cylinders of 1 cm thickness, ranging in size from 0.05 m diameter  to 0.5 m diameter). The target has a value of er of 2.2 and the soil er = 5 and tan d  = 0.2.  The radiated pulse has a center frequency of 1 GHz and an output pulse peak voltage  of 10 volts. 
 On transmitting, all separate  power amplifiers may be energized equally to give maximum power on the target.  The addition of phase shifters shown at the subarray level simplifies the beam-   steering computation, permitting all subarrays to receive identical steering com - mands. They may be replaced by time-delay circuits giving a wide instantaneous  bandwidth (Section 13.7). 
  
 NAL REFLECTIONS AS WELL AS A DISTORTION OF THE ASPECT RATIO OF THE IMAGE OF THE TARGET  CAUSED BY VARIATIONS IN THE VELOCITY OF PROPAGATION 3YMMETRICAL TARGETS  SUCH AS SPHERES OR PIPES  CAUSE MIGRATION OF THE REFLECTED ENERGY TO A HYPERBOLIC PATTERN '02 IMAGES CAN BE PROCESSED TO COMPENSATE FOR THESE EFFECTS  AND THIS IS USUALLY CARRIED OUT OFFLINE ! '02 CAN BE DESIGNED TO DETECT SPECIFIC TARGETS SUCH AS INTERFACES IN ROADS  PIPES  AND CABLES BY MEANS OF POLARIZED RADIATION AND LOCALIZED OBJECTS SUCH AS CUBES  SPHERES  AND CYLINDERS '02 IS CAPABLE OF DETECTING FEATURES MANY HUNDREDS OF YEARS OLD HENCE  A PROSPECTIVE SITE SHOULD REMAIN UNEXCAVATED  PRIOR TO SURVEY  SO AS TO PRESERVE ITS INFORMATION ! SIMPLIFIED DIAGRAM OF THE VARIOUS SOURCES OF CLUTTER IN A '02 ENVIRONMENT IS  GIVEN IN &IGURE   AND IT CAN BE SEEN THAT SEPARATION OF THE VARIOUS SIGNALS IS THE KEY TO IDENTIFYING THE WANTED SIGNAL )NEVITABLY THERE HAVE BEEN SOME CLAIMS FOR '02 CAPABILITY THAT  ARE SIMPLY OUT 
 In optical processing, the electrical signals at the radar output are converted to optical  images on film. The weighting, filtering, and summation of signals are accomplished with the  proper ,optical lenses and transparencies. Optical processing is basically two dimensional so  that processing in the range coordinate is possible with the same apparatus. 
 REFLECTED SIGNALSu !TTENUATION u &OCUSING AND DEFOCUSING u 0OLARIZATION TRANSFORMATION u 0HASE MODULATION u 7AVEFRONT DISTORTION 4ARGET SCATTERING REGIME /PTICAL HIGH FREQUENCY    IE  TARGET SIZE  RADAR WAVELENGTH2AYLEIGH n RESONANCE  IE  TARGET SIZE    OR ^  RADAR WAVELENGTH #LUTTER  u  #AN BE SERIOUS  ESPECIALLY AT SHORT RANGES u  -INIMIZED BY NARROW BEAM  SHORT PULSE  AND DOPPLER PROCESSING,OOK 
 LEMS CONTINUE TO PLAGUE BISTATIC AND MULTISTATIC RADARS AND HAVE BECOME THE TOPICS OF THIS SECTION   BEAM SCAN 
 Nahi: The Detection of Moderately Fluctuating Rayleigh  Targets, IEEE Trans., vol. AES-12, pp. 117-125, March, 1976. 
 The walls are of extremely crude construction, but mas - sive. This monument may constitute one of the oldest stone buildings in Egypt and  hence the world. One of the main goals of the project has been to determine what, if  anything, lies within the enclosure. 
 (8.17b) yields m = l/).0, where A.0 is defined as  the wavelength corresponding to the beam position at broadside. The corresponding  frequency is denoted Jo, and the direction of beam pointing becomes  sin Oo = ~ ( 1 -() = ~ ( 1 -J) (8.18)  If the beam is steered over the limits ± 01 the wavelength excursion ~). is given by  (8.19)  Thus there is a tradeoff between the wavelength excursion and the length of line connecting the  elements. 
 space propagation. Tlie cncrgy is seldom completely trapped, howcvcr, and there IS attenua-  tion dire to tlic leaking of energy from tlie upper surface of the duct as well as by scattering and  absorption. Energy is also scattered out of the duct because of a rough sea si~rface.~~ It has  been foiind cxperimcntally" that S-band radiation (10 cm wavclcngtl.1) is only partially  trapped by the evaporation duct, with attcnuation rates averaging about 0.85 dB/nmi. 
 When h exceeds 38.26 m, the ArcSAR image of target P on the reference plane will severely defocus. We give the simulated imaging results of the target P on the reference plane in Figure 5. When his 0 m, the imaging result of target P on the reference plane has no defocusing because the height of the reference plane is consistent with the actual height of the target at this time. 
 ASV Mk. VIB incorporated attenuator type 58, ﬁgure 4.17, that could be adjusted to increase attenuation at a ﬁxed rate. The rate of increase was set by the operator using control unit type 492, illustrated in ﬁgure 4.18. 
 AP-14(3), pp. 405–406,  May 1966.  93. 
 A firm conclusion in favor of one  polarizatioll or the other is difficult to make for a civil marine radar, but most sets use  . horizontal polarizati~n.~' At high sea states the difference between horizontal and vertical  I polarization is said to disappear.22  Horizontal polarization, as was mentioned in Sec. 13.3, has a probability density functicn  which deviates from Rayleigh more than does vertical polarization when the pulse widths are  short. 
 Taking Hongshan district and Jiangan district (Figure 1) as examples, we compare areas located on carbonate rock belts with the whole of the two urban areas (Figure 8b). The subsidence rate of areas on carbonate rock belts is higher than those of the whole of the two urban areas. However, land subsidence is not signiﬁcant in some other areas located on carbonate rocks or soft soil area. 
 The principle behind the postdetection STC approach is illustrated in Fig. 17.12, where the return of a target in the main beam and a large discrete target in the sidelobes is plotted versus unambiguous range (that is, after the range ambi- guities have been resolved). Also shown are the normal CFAR threshold and the STC threshold versus range. 
 SHIFT CONTOURS. 
 We deﬁne the deformation monitoring accuracy as σd, which can be expressed as [ 7]: σd=λ 4π⎭parenleftBig⎭vextendsingle⎭vextendsingle⎭vextendsingleσps⎭vextendsingle⎭vextendsingle⎭vextendsingle+⎭vextendsingle⎭vextendsingle⎭vextendsingleσpd⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭parenrightBig (35) According to Equation (35), Figures 13and 15, the h–σdcurve can be acquired, as shown in Figure 17. Figure 17. h–σdcurve. 
 T ransmitting Antenna Module The transmitting antenna module consists in a microstrip switch matrix that route the RF signal from a single input to eight stacked patch antennas. The microstrip transmission line and the patch antenna technology allow to fully integrate the module in a single PCB (Figure 6). In Figure 7is shown the Transmitting Antenna Module block diagram: the incoming RF signal is transmitted by a microstrip and pass through a SP4T switch followed by four SPDT switches, this matrix allow to switch the signal between the eight antennas feed lines; immediately before every antenna a power ampliﬁer compensate the losses of the microstrip transmission line and the switch stages   Figure 6. 
 The losses in the microwave feeders and the mixer crystal are not known and rough estimates have been made here for the purposes of performance comparison. Typical overall noise ﬁgures of crystal mixers followed by an IF ampli ﬁer are given in [8] and ranged from 11 dB to 16 dB at 3060 MHz input frequency. The US mixer crystals (silicon diodes) referenced in [ 8] (IN23 and IN23A, B and C) are thought to be similar to the CV101 diodes used in the UK. 
 TIONAL DATA NEED TO BE REFERENCED IS IDENTIFIED ON THE SHIP 4HIS POINT CLEARLY BECOMES OF MAJOR IMPORTANCE WHEN CLOSE 
 Fast recovery is  particularly important when the radar is exposed to impulsive interference. 6.9 I/Q DEMODULATORS Applications.  The I/Q demodulator, also referred to as a quadrature channel  receiver, quadrature detector, synchronous detector, or coherent detector, performs fre - quency conversion of signals at the IF frequency to a complex representation, I + jQ  centered at zero frequency. 
 But it is seldom used in reference  to sea clutter. There are, then, two numbers commonly used to indicate the activity of the sea  surface: a subjective sea state and a measured wind speed. Only when the wind has  sufficient fetch  and duration  to excite a fully developed  sea, can a waveheight be unam - biguously associated with it. 
 Simonett, J. E. Estes, F. 
 The output of  the adder is therefore  /(t) - 2f(t + T) +f (t + 2T)  Input - Output  (a 1  Input Output  -2  Figure 4.9 (a) Double-delay-iine canceler; (h) three-pulse canceler.  MTIANDPULSE DOPPLER RADAR109 V>oc ..><. u OJ OJa V> +­ V> L i.L 100'--_-----'-_---'------'-.JU........1-WoI-L.l...:"--_~___'_~L..J......uJ...L..L_"'_ _____'_">O"'_....1__L...:"_I_!....L:loJ._L.J 1 10 100 1,000 Maximum unambiguous range,nauticalmiles Figure4.8PlotofMTIradarfirstblindspeedasafunction ofmaximum unambiguous range. 
 The frequency range over which the radar operates is often referred to as the  operating bandwidth . Important Characteristics.  The environment in which a radar must operate  includes many sources of electromagnetic radiation, which can mask the relatively  weak returns from its own transmission. 
 Figure 12.20  Non-linear chirp based on the sum of linear chirp and circle -φ chirp.   The corresponding signal amplitude spectrum is shown in Figure 12.21 along with the ampl i- tude characte ristic of a 5 -pole Bessel filter having a 3- dB bandwidth of 0.7  MHz (dotted  curve) as used in the pulse co mpression implementation example below. The matched filter  output corresponding to this nonlinear chirp is shown in Figure 12.22 and the im provement  relative to the linear chirp case in Figure 12.18 is substantial. 
 POLARIZATION   4HE WAVE SPECTRUM USED WAS THE 0HILLIPS SPECTRUM GIVEN IN %Q  (ISTORICALLY  COMPARISONS OF THIS TYPE HAVE BEEN USED OFTEN TO PROVIDE SUPPORT FOR THE "RAGG SCAT 
 Figure 16.24  shows the clutter model for the midrange of angles as a function of frequency.  Eq. PolarizationAngular  Range, °Frequency  Range, GHzConstant   A or M, dBAngle  Slope B  or N, dBFrequency  Slope C,  dB/GHzSlope  Correction D,  dB/(° × GHz) 16.24 aV 20–60 1–6 (1975) −14.3 −0.16   1.12 0.0051 V 20–50 1–6 (1976)  −4.0 −0.35 −0.60 0.036 V 20–70 6–17  −9.5 −0.13   0.32 0.015 H 20–60 1–6 (1975) −15.0 −0.21   1.24 0.040 H 20–50 1–6 (1976)  −1.4 −0.36 −1.03 H 20–70 6–17  −9.1 −0.12   0.25 16.24 bV and H 0 1–6 (1975)  7.6   . 
 CRAFT  WHICH IS OPERATED BY THE .AVAL 2ESEARCH ,ABORATORY AND COVERED BY A ROTATING &)'52%     2APID 
 13.20 .—D-c restorer, video signals areapplied isoperating inthecorrect voltage range. ThkI isparticularly important inthe intensity modulation ofacathode-ray tube where thetube must bejust cutoffforzero signal amplitude. The d-crestorer can beused tofixthestarting point ofasweep byclamping thedeflecting plate ofanelectrostatic tube, orthegrid ofadirect-coupled sweep amplifier, between sweeps. 
 TRACKING NOISE VERSUS RANGE USING A  
 ¤ ¦¥³ µ´P    WHERE K AND N ARE PARAMETERS OF THE WEIGHTING FUNCTION   " IS THE SWEPT BANDWIDTH OF  THE WAVEFORM  AND n"  a F a " 4HIS IS A COSN WEIGHTING ON A PEDESTAL OF HEIGHT  K  &IGURE   (AMMING WEIGHTING IS ACHIEVED FOR N    AND K   0OLYPHASE  #ODE 0HASE 0HASE VS 4IME #HARACTERISTIC.    %XAMPLE !UTOCORRELATION D" .    %XAMPLE  &RANKP .IJ   
  '(Z  4HE ANTENNA ROTATES AT  RPM AND  HAS A  ONE 
 UATED SUFFICIENTLY SO THAT THEY DO NOT MODULATE THE PHASE OF THE TRANSMITTED PULSES )F THE POWER CONDITIONER FREQUENCIES CANNOT BE SUFFICIENTLY ATTENUATED  THEIR FREQUENCY SHOULD BE SYNCHRONIZED TO A MULTIPLE OF THE 02& OF THE #0) SO THAT MODULATIONS REPEAT  PRECISELY PULSE 
 In addition, the dc power source must include appropriate energy storage,  sometimes locally in the module, in order to support the minimum voltage pulse droop  as a function of time. Environmental Protection Considerations.  MMIC components utilize thin-film  metal deposition techniques to delineate the very fine features that make up the micro - wave circuitry. 
 Weight considerations have prevented the development ofthree-axis scanners forairborne use. We have mentioned adistortion inthe display ofanelevated target observed from arocking ship. Aclosely related distortion inbearing is present even forsurface targets: the deck-tilt error. 
 If the target falls  in the sidelobe clutter region, the range performance will be degraded, since the  total interference power (system noise plus clutter) against which the target must  compete is increased. The foregoing discussion can be applied to the sidelobe clut - ter region, however, by interpreting Ro as the range where the signal is equal to  sidelobe clutter plus system noise.74–76 The CFAR loss may also be higher owing  to the increased variability of the threshold when the clutter varies over the target  detection region. More accurate calculations of detection performance in the side- lobe clutter limited case should include the proper clutter RCS fluctuation models  and CFAR techniques.77 LIST OF ABBREVIATIONS AESA active electronically scanned array A/D analog-to-digital AGC automatic gain control AM amplitude modulation CAGC clutter automatic gain control CFAR constant false alarm rate CNR clutter-to-noise power ratio CPI coherent processing interval CW continuous wave ∆AZ delta-azimuth antenna beam (used for monopulse angle estimation) ∆EL delta-elevation antenna beam (used for monopulse angle estimation) dBc decibels with respect to the carrier DC direct current DFT discrete Fourier transformFIGURE 4.22  Single-scan vs. 
 ROBBING DECREASE IN HEAD WIND  WHICH CAN CAUSE THE PLANE TO CRASH IF ENCOUNTERED SHORTLY BEFORE TOUCHDOWN OR JUST AS THE AIRCRAFT IS TAKING OFF -ORE COMPLETE DESCRIPTIONS OF MICROBURSTS AND THEIR EFFECTS ON AVIATION SAFETY ARE GIVEN BY &UJITA   AND -C#ARTHY AND 3ERAFIN &)'52%     -EASUREMENT OF ROTATION OR AZIMUTHAL WIND SHEAR IN A MESOCYCLONE   A ROTATING WIND PARCEL 4HE AZIMUTHAL SHEAR IS GIVEN BY  #V#X   VRR@ #OURTESY OF  5NIVERSITY #ORPORATION FOR !TMOSPHERIC 2ESEARCH Ú   "OULDER  #/  . £°Îä  2!$!2 (!.$"//+  -ICROBURST DETECTION  LIKE TORNADO DETECTION  IS ACCOMPLISHED BY ESTIMATING SHEAR  (OWEVER  IN THE CASE OF THE MICROBURST  IT IS THE RADIAL SHEAR OF THE RADIAL VELOCITY THAT IS  TYPICALLY MEASURED (UMAN INTERPRETATION OF MICROBURST SIGNATURES IN COLOR 
 The power supply should include aconventional rectifier and LC-filter toprovide the300 volts direct current and anW’-fdtered negative supplv. SEC. 13.13] DESIGN OF A-SCOPES 525 Trigger FlipflopandBInverting C7 —sawtooth gen.-amplifier &.andV2 V,* A m+250v Video Video amplifier1- _+300v V3--.-4Focusi---- YIntensity Flipflop Sweepgenerator Inverter , -+300!4 1 I<---lOOk 150k 11 11 1 —+300V -— 120k lW v. 
 ABILITY   &OR EFFICIENT MULTIPLE 
 L. Frush, “Coherent wideband processing of distributed targets,” in Proc.  Int. 
 This is the range at which the leakage signal and its  noise conlponents (including microphony and vibration) are found. At greater ranges, where  the target is expected, the effect of the Jo Bessel function is to reduce the echo-signal amplitude  in comparison with the echo at zero range (in addition to the normal range attenuation).  Therefore. 
 24.14 for 1800 UTC (day). For the night case, the concentric spherical assumption from the 700-km downrange position will give paths that are slightly long for one-hop ranges. In the two-hop ranges the no-gradient assump- tion causes more distortion. 
 D. S.: Continuous Wave (CW) Radar, EASCON '75 Record, IEEE Publ. 75 CHO 998-5  EASCON, rr I07-A to 107-G, 1975. 
 Theantenna patternEa(¢)canbeconstructed fromthesamplevaluesE,(lIA/d) witha patternoftheform(sin"')N abouteachofthesampled values,where'" =rr(d/A)sin¢.The (sin1//)/tI!function iscalledthecomposilJg flmctiolJ andisthesameasthatusedininformation. 3x 2X X -- -- -- x 21 2 g 5L sin#  ddd O Zddd d  31 2X: X - -- -- -- A 3_1 4_1: sin$  ddd ddddd  x 2JafiQ 3x 2x X 0 - -- -- --  ddd ddddd Figure 7.23 (a) Radiation pattern  E(4) with sampled values 1/11 radians  apart, where d = aperture dimen-  sion; (b) sampled values E,(nA/d),  which specify the antenna pattern of  (a); (c) reconstructed pattern E,(+)  using (sin $)I$ composing function  to approximate the desired radiation  pattern E(4).  theory to construct the time waveform from the sampled values. 
 Furthermore, simulations with three point targets at di ﬀerent heights were performed to verify the proposed method in a scene with height variations. The targets D, E, and F had the same range position and RCS and were located at ( −10 m,−10 m), (0 m, 0 m), and (10 m, 10 m), where ( y,z)a r e the (azimuth, height) coordinates. Figure 7a,b showed the contour plots of the IRF using the classical 2D focusing algorithm with a Taylor window in azimuth and the proposed method. 
 85. Barton. D. 
 PRESSED 
 Also at the feed, the polarization is in its purest form, so the vector properties are best known at this point and are described in many textbooks. In the analyses that follow, the constants are usually stripped away from the textbook versions since the antenna designer's primary goal in analysis is normally to determine the an- tenna's gain and pattern for main and cross polarizations. Therefore, the designer will normally integrate the power radiated from a feedjnto a sphere to determine the normalization factors needed. 
 S 4IME 
 U. R., and G. D. 
 BASED SYSTEMS  MUST BE  DESIGNED TO MINIMIZE MASS AND TO MAXIMIZE EFFICIENCY AND LONGEVITY -ASS  POWER  AND LIFETIME EMERGE AS DRIVING THEMES THAT DICTATE CONSERVATIVE DESIGN  GENEROUS MARGINS DURING SYSTEM IMPLEMENTATION  AND REDUNDANCY OFTEN REALIZED BY DUAL 
 An analysis of the performance of typical implementations of clutter maps has been  discussed in Khoury and Hoyle.46 From this reference, a typical transient-response  curve is shown in Figure 2.91 for a single point clutter source 20 dB above thermal  noise that fluctuates from scan-to-scan according to a Rayleigh probability density  function, a filtering constant of a  = 0.125 and assuming four returns noncoherently  integrated in each clutter map cell. The abscissa is in radar scans, and the ordinate is  probability of detection of the point clutter source. Since the clutter point has the same  amplitude statistics as thermal noise, the output false-alarm rate approaches Pf = 10−6  asymptotically. 
 AMS , vol. 80,   pp. 381–388, 1999. 
 When a target does not appear in the small  gate, a larger gate would be used whose search area is determined by the maximum accelera­ tion expected of the target during turns.  On the basis of the past detections the track-while-scan radar must make a smoothed  estimate of a target's present position and velocity, as well as a predicted position and velocity.  One method for computing this information is the so-called a-fJ tracker (also called the g-h  tracker84), which computes the present smoothed target position\ x" and velocity I hy the  following equations 72 '  Smoothed position: Xn = Xpn + a(xn -Xpn)  Smoothed velocity: Xn = Xn -1 + ~ (xn -X pn) (5.8)  (5.9)  where xP" = predicted position of the target at the nth scan, x,, = measured position at the nth  scan, a = position smoothing parameter, fJ = velocity smoothing parameter, and Ts = time  between observations. 
 10.4. 26. N. 
  A FILTER EQUATIONS WHERE  @ AND A VARY WITH TIME 4HE +ALMAN FILTER UPDATE  PROCEDURE CONTINUES AS FOLLOWS &IRST  PREDICT A NEW TARGET STATE ESTIMATE 8T TKK  \  OF THE STATE  8TK   AT TIME  TK   GIVEN ALL MEASUREMENTS UP TO TIME TK  8T T T 8T ! TKK K K P K    \          F   ALONG WITH ITS COVARIANCE   0K    \ K    E¼TK 0K \ K E¼TK 4   1TK     4HEN  UPDATE THE TARGET STATE USING THE K    ST RADAR MEASUREMENT  8T T 8T T + 9 (T 8KK KK K K K         
 For example, a high threshold value leads to a small “false alarm rate”, however,  at the same time leads to a reduced probability of detection.     Figure 6.7  “False alarm rate” dependent upon the position of the detection threshold.   If one would like to obtain quantitative predictions dependent upon the threshold and upon the  noise power density, then generally the probability density p(UN) of the noise voltage UN is  . 
 Hence 11 divides the radiation pattern into a  uniform sidclobc region straddling the main beam and a decreasing sidelobe region. The  numher of~cqual sidelobes on each side of the main beam is 11 -l.  The bcamwidth of a Taylor pattern will be broader than that of the Dolph-Chebyshev. 
 CANT 
 Atthetime this system was designed, faster planes were not common. Even so, asomewhat longer wavelength might have been desirable, but 10cmwas chosen because good tubes were available atthis wavelength. This wavelength proved satisfactory, but itsometimes gives doppler frequencies rather below thefrequency region inwhich theearissensitive. 
 152. D. L. 
 Goldstein. G. B.: False-Alarm Regulation in Log-Normal and Weibull Clutter, IEEE Trans., vol. 
 SIDEBAND MIXER SHOWN IN  &IGURE  4HE 2&  HYBRID PRODUCES A  n PHASE DIFFERENTIAL  BETWEEN  THE ,/ INPUTS TO THE TWO MIXERS 4HE EFFECT OF THIS PHASE DIFFERENTIAL ON THE  )& OUTPUTS OF THE MIXERS IS A   n SHIFT IN ONE SIDEBAND AND A  
 Ê  
 The  penalty paid for this procedure is a long observation time.  3  Frequency agility. If tile frequency of a pulse of length r is changed by at least l/s, the echo  from uniformly distributed clutter will be decorrelated. 
 8. R. L. 
 For example, soil moisture monitoring is best within 20° of ver - tical at frequencies near 5 GHz. Vegetation discrimination is better, however, at higher  frequencies and angles of incidence. For some applications, use of the full polarization  matrix, including the phase, is useful. 
 The adimension isadjusted within afew FIG.9.21.—End view ofAN/APQ-7 scanner. thousandths ofaninch asmeasured byaninside micrometer, after which theantenna issetupand itsgain maximized byadjustment ofthetoggle FXG. 9.22.—Construction ofdipoles used inAN/APQ.7 antenna.screws. 
 Notice that the LS residual, ri,res, can be rewritten as ri,res=Φiβi,βi=si−si,init. (12) CS-Residual In this step, CS is implemented on the LS residual, i.e., solve ( 12) with CS in the following model min βi/bardblri,res−Φiβi/bardbl2 2+λ/bardblβi/bardbl1. (13) Iterative shrinkage thresholding algorithm (ISTA) [ 19] can be used to solve ( 13). 
 In order to ensure that the most coherent points were distributed over the highway among the 57 total interferometric pairs, we selected the interferograms carefully and deleted those with bad coherence and less points along the route. Consequently, only 25 high-quality pairs with densely distributed coherence pixels over the highway region were selected. The subsequent experiments, including rheological parameter estimation and time-series deformation inversion, were carried out using MATLAB. 
 Hovanessian, S. A.: An Algorithm for Calculation of Range in a Multiple PRF Radar, IEEE Tru~ts.,  vol. AES-12, pp. 
 SUREMENTS !T EACH DETECTION TIME   T K  ONE OF THE SEVERAL FILTER OUTPUTS MUST BE SELECTED  TO BE THE TRACK STATE USED FOR DETECTION TO TRACK ASSOCIATION ! SYSTEMATIC WAY OF EMPLOYING MULTIPLE TARGET MOTION MODELS IS THE )NTERACTING  -ULTIPLE -ODEL )--  APPROACH DIAGRAMMED IN &IGURE  -ULTIPLE MODELS RUN  SIMULTANEOUSLY HOWEVER  THEY DO NOT RUN INDEPENDENTLY )NSTEAD  THERE IS MIXING OF +ALMAN &ILTER  #OORDINATE &RAME 6ARIANTS#OORDINATES FOR 'AIN #ALCULATION %QS     AND STATE UPDATE %Q  #OORDINATES FOR 3TATE 0REDICTION %QS    -ETHOD OF #OVARIANCE 0ROPAGATION!DVANTAGES $ISADVANTAGES 0OLAR +ALMAN FILTER0OLAR 0OLAR %QS  TO   IN POLAR COORDINATES&ILTER COVARIANCES ARE CALCULATED EXACTLY AND STATE ERRORS GAUSSIAN DISTRIBUTED 2ADAR DETECTIONS OF LESS THAN THREE DIMENSIONS CAN BE USED0SEUDO 
 Supposing that there are at least four interferometric pairs generated, the unknown parameters over all high coherent points of each image can be solved and, consequently, the corresponding rheological parameters can be estimated. 2.4. Unknown Parameter Estimation The estimation of the unknown parameters in Equation (8) is a non-linear parameter estimation problem. 
 Sales No. E.83.IX.3. 15. 
 This device depends on tile use of a limiter.  Limiters, however, can generate undesired spurious responses and small-signal suppression.  and reduce the improvement factor that can be achieved in MTI processors. 
 Objectionable modulation ofthe transmitted pulse bythe use of 60-cps power ontheheater hasbeen observed with thetype 4J47. This is probably caused bythe magnetic field .oftheheater current. Nosuch difficulty has been found with the2J32, owing apparently tothedesign andconstruction oftheheater. 
 The amount of isolation which can  be readily achieved between the arms of practical hybrid junctions such as the magic-T, rat  race, or short-slot coupler is of the order of 20 to 30 dB. In some instances, when extreme  precision is exercised, an isolation of perhaps 60 dB or more might be achieved. One limitation  of the hybrid junction is the 6-dB loss in overall performance which results from the inherent  waste of half the transmitted power and half the received signal power. 
 M RESOLUTION   
 Because the thickness is very critical and cannot be controlled adequately, the stripline is placed in an oven whose temperature is adjusted to control the final operating frequency. One side of the strip is treated with an absorbing material to prevent reflections which could excite a wave that is not longitudinal and could thus introduce spurious signals. Aluminum strip delay lines have the lowest losses, but their center frequency and bandwidth must be kept low. 
 MANCE  EITHER DISTORTING THE COMPRESSED PULSE SHAPE OR DEGRADING SIDELOBE PERFORMANCE 3ECTION   0HASE ERRORS CAN BE MEASURED USING A TEST TARGET INJECTED INTO THE RECEIVER AND MEASURING THE PHASE RIPPLE AT THE RECEIVER OUTPUT "Y PERFORMING THIS MEASUREMENT WITH TARGETS INJECTED AT DIFFERENT SIMULATED RANGES  THE ERRORS ASSOCIATED WITH THE RECEIVER ,/ AND TEST SIGNAL CAN BE SEPARATED #ORRECTION OF RECEIVER ,/ PHASE DISTORTION CAN BE READILY CORRECTED WHEN USING A DIRECT DIGITAL SYNTHESIZER AS DESCRIBED IN 3ECTION  È°ÈÊ  Ê " /,"  3ENSITIVITY 4IME #ONTROL 34#   4HE SEARCH RADAR DETECTS RETURNS OF WIDELY DIF 
 LEVEL #7 PHASE NOISE FLOOR REQUIREMENT  
 20.6« illustrates performance for a linear-odd delta beam aperture illumination. The ac- tual monopulse sensitivity factor can be calculated from the normalized sensitiv- ity once the aperture height and RF wavelength have been specified. As an ex- ample, if ZA = 31.75, the boresight monopulse sensitivity factor corresponding to the linear-odd delta beam illumination function is 0.05715 V/(V-msine). 
 Part 1: characteristics,” Electronics & Communications Engineering  Journal , vol. 14, no. 2, pp. 
 But waves propagate, so even in the absence of local wind, there can be significant local wave motion due to waves arriving from far away, perhaps from a distant storm. Waves of this type are called swell, and since the surface over which the waves travel acts as a low-pass filter, swell components often take the form of long- crested low-frequency sinusoids. The Wave Spectrum. 
  
 Theincreased threshold neededtoavoidfalsealarmsissignificant (toto20dB,ormore,in somecases). Thelog-normal probability densityfunction hasbeenproposed tomodeltheclutter echowithveryhigh-resolution radarandatthehigherseastates,Ifthecluttercrosssection islognormal, theprobability densityfunction describing itsstatistics is (13.11a) p(oJ=-~_.exp[----~2(In(Je)2j .J'21T.(J(je 2(J (J1n whereac=cluttercrosssection am=medianvalueofae a=itandard deviation ofInae(natural logarithm) Theprobability densityfunction thatdescribes thestatistics ofthevoltageamplitude atthe outputoftheenvelope detector whenEq.(13.11a) istheclutterinput,isgivenby p(l')=---=;---exp[-~(21n~)21 (13.1Ib)j2nav 2(J Vln where I'misthemedian valueofvand(Jremains thestandard deviation ofIn(Je.t14Afit ofthelog-normal probability densityfunction with(]=6dBtoactualdataforseastate2 toJisshowninFig.13.5.12Themedian valueofthetheoretical distribution inthiscase wasequated tothemedianoftheactualdataandthe(Jwasselected tominimize themaximum difference indBbetween thetheoretical curveandtheactualdata. Withmanyradarsthatoperate inthepresence ofseacluttertheRayleigh pdfgenerally underestimates therangeofvaluesobtained fromrealclutter,andthelog-normal pdftendsto overestimate therangeofvariation. 
 All four feeds generate the sum pattern. The difference pattern jn one plane  is formed by taking the sum of two adjacent feeds and subtracting this from the sum of the  other two adjacent feeds. The difference pattern in the orthogonal plane is obtained by adding  the differences of the orthogonal adjacent pairs. 
 SERVED BY EXACT 
 Unsupervised Change Detection in Satellite Images Using Principal Component Analysis and k-Means Clustering. IEEE Geosci. Remote Sens. 
 Li, F.; Held, D.; Curlander, J.; Wu, C.; Curlander, J. Doppler Parameter Estimation for Spaceborne Synthetic-Aperture Radars. IEEE T rans. 
 Anexamination oftheBesselfunctions (Fig.3.16)showsthatifoneofthemodulation­ frequency harmonics isextracted (suchasthefirst,second,orthirdharmonic), theamplitude oftheleakage signalatzerorangemaytheoretically bemadeequaltozero.Thehigherthe numberoftheharmonic, thehigherwillbetheorderoftheBesselfunction andthelesswillbethe amount ofmicrophonism-Ieakage feedthrough. Thisresultsfromtheproperty thatJ"(x)be­ havesasx"forsmallx.Although higher-order Besselfunctions mayreducethezero-rangc response, theymayalsoreducetheresponse atthedesiredtargetrangeifthetargethappens to fallatorncararangecorresponding toazerooftheBesselfunction. Whenonlyasingletarget isinvolved, thefrequency excursion ~rcanbeadjusted toobtainthatvalueofDwhichplaces themaximum oftheBesselfunction atthetargetrange. 
 At the lower frequencies, where coaxial components are prevalent, dipoles have been favored. A ground plane is usually placed about X./4 behind an array of parallel dipoles so that the antenna forms a beam in only one hemisphere. At the higher frequencies open-ended waveguides and slots are frequently used. 
 It can be understood as, if the last momentum (i.e., v) is the same as the negative gradient direction of this time, then the magnitude of this decline will increase. By using momentum, we can accelerate the convergence process [ 29]. 2.2.3. 
 Most obvi - ously, the 11-year solar cycle forces changes to spectrum usage and the density of users,  with a resultant impact on HF radar channel selection. Another trend that has become  apparent in recent years is the gradual reduction in HF users as services move to satel - lite communications, microwave links, fiber optics, and other media. Nevertheless, the  increased number of HF radars has led to a new challenge: inter-radar interference and  the need for frequency arbitration. 
 vol 41. pp. 549 550. 
 7.39  7.6 Quantizat ion Effects  ...............................................  7.43  Phase Quantization  ...........................................  7.43 Periodic Errors  ................................................... 
 These factors affect many ofthe variables ofthedesign, such asthetypes ofantennas chosen, ther-fpower necessary, the carrier frequency most desirable, and the mechanical construction oftheequipment. 17.10. Antennas, Frequencies, and theRadiation Path.-The antenna gain should beashigh aspracticable atboth stations. 
 CESS THAT RESULTS IN GENERATION OF FREQUENCIES THAT ARE LINEAR  COMBINATIONS OF THE FUN 
 AP-12, pp. 685-691, November, 1964.  21. 
  
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 In the MTD, one or more high-resolution clutter maps are used to suppress the  clutter residues, after doppler filtering, to the receiver noise level (or, alternatively, to  raise the detection threshold above the level of the residues). 
 Cartesian/ Earth- Centered  Kalman  filter53Cartesian/   Earth-centeredCartesian/   Earth-centeredEqs. 7.29 to 7.33  in Cartesian/  Earth-centered  coordinatesState propagation  is linear  (no pseudo- accelerations).Filter  covariances are  not exact due  to nonlinear  transformation. Extended/  dual  coordinate  Kalman  filter54Polar Cartesian/   Earth-centeredEqs. 
 ,ENGTH 3EQUENCES  -AXIMAL 
 If it is assumed that the noise contributions enter the receiver via the main beam only, the  PROPAGATION OFRADAR WAVES463 maximum occurswhentheantenna isdirected alongthehorizon. Thenoiseisgreateralong thehorizonthanatthezenithsincetheantenna" sees"m.oreatmosphere. Theantenna beams mustbeoriented atelevation anglesgreaterthanabout5°toavoidexcessive atmospheric­ ahsorption noiseinthemainbeam. 
 Echoes from water towers and build- ingfaces may easily equal ininten- sity the composite echo obtained from amountainside. However, echoes from structures aregenerally found tobefairly steady since the targets donotsway much inthewind and donot present aserious cancellation problem when theantenna is stationary. Most ground clutter iscomposite inthesense that theecho amplitude atagiven instant isthevector sum ofmany small echoes from theindi- vidual targets scattered over aland area determined bythebeamwidth. 
 and Remote Sensing , vol. 33,  pp. 896–904, 1995. 
 (ILL "OOK #OMPANY      - 7 ,ONG   2ADAR 2EFLECTIVITY OF ,AND AND 3EA   RD %D  .ORWOOD  -! !RTECH (OUSE      $ #ROMBIE  h$OPPLER SPECTRUM OF SEA ECHO AT  -CS v  .ATURE  VOL   PP n     * 7 7RIGHT  h! NEW MODEL FOR SEA CLUTTER v  )%%% 4RANS  VOL !0 
 14.9) was first developed inEngland, where itisknown asthe Newton regulator after the inventor. The variable resistance element consists ofastack ofcarbon disks orannular rings placed inaceramic ortempered-glass cylinder. The cylinder ismounted inametal housing which serves to dissipate the heat from the pile and gives structural support. 
 BEAM CLUTTER MAY BE THE LARGEST SIGNAL HANDLED BY THE RADAR WHEN IN A DOWN 
 This is equivalent to using a single pixel to represent the whole target. Next, we can calculate the aspect entropy of the target using (1) and (2). The aspect entropy is now applicable to the scattering anisotropy analysis at the target level. 
 Some receivers, however, might employ limiting for some special  purpose, as for pulse compression processing for example.  Limiting results in a loss of only a fraction of a decibel for a large number of pulses  iritegrated, provided tllc limiting ratio (ratio of video limit level to rms noise level) is as large as  2 or 3.'' Other analyses of bandpass limiters show that for small signal-to-noise ratio, the  , redtiction in the signal-to-noise ratio of a sine-wave imbedded in narrowband gaussian noise is  n/4 (about 1 dB).53 However, by appropriately shaping the spectrum of the input noise, it has  been suggested54 that the degradation can be made negligibly small.  Collapsing loss. 
 CurveA,chemical recorder; curveB,cathode-ray­ tubeB-scopedisplay; curveC.lineofslope1.5dB/doubling (ocn1/2);curveD,lineofslope3dB/doubling (rxn)forperfectpredetection integration. A'Saretheoretical valuesforidealpostdetection-integration improvement ascomputed byMarcum43forafalse-alarm probability of10-3.(FromJ.Brit.IRE.49) 2.5dBperdoubling mentioned above.Theapplicability oftheseparticular teststotheusual PPJdisplaycanbequestioned sincea5-inch-diameter CRTwasusedwithsimulated echoes placedatanazimuth unknown totheoperator atadistance of1inchfromthecenterofthe scope.Theconclusion thatmightbedrawnfromsuchexperiments isthatsomewhat lessthan theoretical integration improvement willbeobtained ifthepulsesarenotdisplayed properly; thatis,thepersistence ofthedisplayshouldbesufficient toprevent excessive "lossof memory," thedynamic rangeofthedisplaymustbelargeenoughnottolosesignalinforma­ tion,andthedisplayresolution shouldbeconsistent withtheradarresolution toavoid collapsing loss.Sincethedynamic rangeofmostdisplays islimitedtoarelatively smallvalue, thepulsesreceived fromatargetshouldbedisplayed sidebyside(asisusuallythecaseona PPIorB-st"ope) ratherthanpiledupatasinglepointonthedisplay.Insuchacasethe integration isperformed bytheeye-brain combination oftheoperator. Experimental measurements oftheoperator's abilitytodetectsignalsonanA-scope showedtheintegration-improvement factortoben1/2,or1.5dBperdoubling ofthenumberof pulsesintegrated.31Thisislessthanpredicted foranidealpostdetection integrator. 
   )NTERNATIONAL  4ELECOMMUNICATION 5NION  'ENEVA  ! 0 .ORRIS  h4HE FUTURE OF RACONS v &INAL 2EPORT  #ONTRACT .O   'ENERAL ,IGHTHOUSE  !UTHORITIES  ,ONDON    h'LOBAL MARITIME DISTRESS AND SAFETY SYSTEM '-$33 0ART  2ADAR TRANSPONDER-ARINE SEARCH  AND RESCUE 3!24  v )%#  
 ING HIGH 
 For example, circular SAR (CSAR) has a circular trajectory in order to observe the target at 360 degrees [ 5–7]. The aperture is so long that scattering differences in azimuth must be considered. The anisotropic scattering behavior is also a useful feature that can be obtained via CSAR. 
 The radar range equation for CW or coherent pulse radars30  is modified for bistatic operation and then solved for the bistatic maximum range  product, ( RT RR)max:  ( )( ) ( /max R RP tG G F F kTF E NT Ro T R B T R o n=av λ2 2 2 34s πo o T RL L)/  1 2  (23.2) where  RT = Transmitter-to-target range (m)  RR = Receiver-to-target range (m)  Pav = Transmitted average power (W)  to = Signal observation (or integration) time  GT = Transmitting antenna power gain  GR = Receiving antenna power gain  l = Wavelength (m)  sB = Bistatic radar cross section (m2)  FT = Pattern propagation factor for transmitter-to-target path  FR = Pattern propagation factor for receiver-to-target path  k = Boltzmann’s constant [1.38 × 10–23 J/K]  To = Standard temperature [290 K]  Fn = Receiver noise figure  E/No = Received energy to receiver noise spectral density required for detection  LT = Transmitting system losses ( >1)  LR = Receiving system losses ( >1) Equation 23.2 assumes that a matched filter, or an equivalent matched filter such as  a cross-correlator, is used on reception. Equation 23.2 is related to the corresponding  monostatic maximum range equation by RT RR = RM2 and sM = sB, where sM is the  monostatic radar cross section.  For pulsed radar operation, to = n / fp, where n is the  number of pulses integrated and fp is the pulse repetition frequency. 
 As with sea  state, reported surface truth correlations will suggest  refinements to the wind-speed process that may also be  incorporated prior to the Exact Repeat Mission.  Height Corrections  Adjustments to the height data include a correction  for the Doppler-induced offset that is characteristic of  the linear FM waveform, a long-term-drift term deriv­ able from the on-board calibrate mode data, an initial  bias correction determined during ground test, an ad- 30r-------.--------.--------.-------~  25  =0  c::  0 20 u  Q)  (/)  a; a.  ~  ~ 15 Q)  E  'D  Q)  Q) a. 
   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°{x  % !RONOFF AND . 'REENBLATT  h-EDIUM 02& RADAR DESIGN AND PERFORMANCE v (UGHES !IRCRAFT  2EPORT  PRESENTED AT )%%% .ATIONAL 2ADAR #ONFERENCE   ( %RHARDT  h-02& PROCESSING FUNCTIONS 
  " "  4AYLOR 
 D. M .. and II. 
 Sequential observer. Most radars utilize the equivalent of the Neyman-Pearson Observer and  operate with a fixed number of pulses. However, the detection decision might very well be  made on the basis of only a few observations or possibly a single observation, and it would not  be necessary to record the later observations that occur once the threshold has been crossed. 
 This indicates that a majority of the non-linear deformation may not be reﬂected in the residual phase of the linear velocity model when a substantial real non-linear deformation has occurred. Therefore, the obtained non-linear deformation result, isolated from the residual phase of the linear model, may have a large deviation from the real value; thus, it shows a signiﬁcant di ﬀerence from the rheological model. As shown in Figure 10, the overall deformation sequences obtained by the rheological model displayed an obvious non-linear trend, whereas temporally continuous linear subsidence characteristics were displayed by the linear model. 
 The most frequently expressed width is the half-power beamwidth (HPBW), which occurs at the 0.707-relative-voltage level in Fig. 6.2a and b, at the 0.5-relative- power level in c, and at the 3 dB level in d. Sometimes other beamwidths are specified or measured, such as the one-tenth power (10 dB) beamwidth, or the width between nulls, but unless otherwise stated the simple term beamwidth im- plies the half-power (3 dB) width. 
 8, of" Insect Flight," R. C. Rainey (ed.),  Blackwell Scientific Publications. 
 NIQUES &OR EXAMPLE  &4# ALLOWS THE DETECTION OF SIGNALS THAT ARE GREATER THAN CLUTTER BY PREVENTING THE CLUTTER FROM SATURATING THE COMPUTER &4# DOES NOT PROVIDE SUB 
 Condley, “Some system considerations for electronic countermeasures to synthetic aperture  radar,” IEE Colloquium on Electronic Warfare Systems , January 14, 1991, pp. 8/1–8/7. 167. 
 SUREMENTS WERE IN THE  TO  RANGE OF INCIDENCE ANGLES -EASUREMENTS NEAR VERTI 
 ORBIT SCHEDULING IS TO FOCUS ON SIX hDEFAULTv MODESFOUR hOPERATIONALv AND TWO hSEMI 
 1960. 14.Phillips. R.M.:HighPowerRing-Loop Traveling-Wave TubesforAdvanced Radar,MicrowQl'e ."IrS(1'/11NI'\\'S.vol.5.pp.4741).Fehruary /March.1975. 
 Due to Bulk Carrier’s distinct shape and size characteristics, it is easy to classify. As shown in Table 8, we can entirely classify the Bulk Carrier images. Consider Container Ships and Oil Tankers, distinguishing between them is a challenge in ship classiﬁcation, because they have similar shapes and sizes. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft.  MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 begins with an airfield or carrier takeoff, continues through flight penetrating into  an enemy battle-space, searches for air targets to attack, and ultimately returns to  the starting point. 
 BAND SPURIOUS CANNOT NORMALLY BE IMPROVED WITH FILTERS BECAUSE IT OCCURS WITHIN THE SAME FREQUENCY RANGE AS THE DESIRED SIGNAL SPECTRUM !TTEMPTS TO USE NOISE DEGENERATION TO REDUCE THE INHERENT 2& TUBE NOISE LEVELS ARE SUBJECT TO LIMITATIONS )N 
 Jacornini, 0. J.: Weighting Factor and Transmission Time Optimization in Video MTI Radar, IEEE  Tratts., vol. AES-8, pp. 
 It should not be confused  with the circuit-theory concept of impedance matching, which maximizes the power transfer  rather than the signal-to-noise ratio.  The frequency-response function of the matched filter is the conjugate of the spectrum of  the received waveform except for the phase shift exp ( -j2nft 1 ). This phase shift varies uniformly  with frequency. 
 If the number of jammers is higher, the adaptive array is still useful because  some jammer suppression is achieved with an accordingly reduced detection range.  ‡  The Marcum Q function is defined as Q a b xx aI ax d xob( ,) e xp ( ) = −+ ∞∫2 2 2 where Io (.) is the modified Bessel function of order 0. ch24.indd   22 12/19/07   6:00:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 VGG-16 net also performs well. Because of the good performance in Densenet-121, we guess that with deeper networks, further improvement may be attained. 3.7. 
 ORBIT 4HE ORBIT  ALTITUDE NORMALLY MAY BE CHOSEN TO TUNE THE PERIOD AND %ARTH ROTATION RATE SO THAT AN EXACT 
 J. Wurman, M. Randall, C. 
 BROADENED TECH 
 ISAR motion compensation using modiﬁed Doppler centroid tracking method. T rans. Nanjing Univ. 
 WhenH(f)isnormalized' tounityatmidband (maximum-response frequency). H(fo)=1.Thebandwidth BIIiscalled,the noisebandwidth andisthebandwidth ofanequiva­ lentrectangular filterwhose noise~poweroutput isthesameasthefilterwithcharacteristic. THE RADAR EQUATION 19  I!(/ ) '1 lic 3-ti13 I~i~r~tlwitltli is tlcfirictl as tlic scparntioti it1 licrtz betwceri tlie poitits oti tlic  frequericy-resi~otisc cliaractcristic wliere the response is reduced to 0.707 (3 dB) fro111 its r~iaxi-  nlilm valric. 
 K.: A Half Century of Radar, IEEE Trans., vol. MTT-32, pp. 1161-1169, September 1984. 
 Figure 18is an optical picture and enlarged fusion result of the transport vehicle of Figure 18. Different colors represent components of different views. In a single view image, the occluded portion can be supplemented by another view. 
 T.. T. F. 
 On the radar screen man-  made objects, such as factories, show up very strongly,  the radar echoes back from these objects (with their very  numerous walls and reflecting surfaces) being powerful,  Reflections from land are much weaker, being slightly  diffused, whereas the flat surface of water gives almost  no reflection at all back in the direction of the aircraft.  The decision to install this new aid soon followed;  production on a superlative scale of speed and priority,  under the personal urge of Winston Churchill, was the  greatest of all ‘crash’ programmes of radar production,  but it was vital to keep the enemy in the dark about the  purpose of this novel device, even when he had some  evidence that new fittings were appearing in our aircraft.  So it was to be Known as a ‘homing device.’ The initials  BN, for ‘blind navigation,’ by which it had been known,  were thought too suggestive, and as a name which would  give nothing away, H2S was suggested; and H2S has  thus come to be the general title for all such equipments. 
 February, 1948. 51.Baker,C.H.:..ManandRadarDisplays," TheMacmillan Company, NewYork,1962. 52.Swerling, P.:The"DoubleThreshold" Method ofDetection, RandCorp.Rept.RM-l008, Dec.17, 1952,SantaMonica, Calif. 
 DOMAIN DIGITAL PULSE COMPRESSION PROCESSOR OPERATES ON THE PRINCI 
 McKay. M. W.: The AN/APN-96 Doppler Radar Set, IRE Natl. 
 An indication of height was obtained by  measuring automatically the angle of the line of maxi-  mum. reception of the echo. If we could measure this  angle and ascertain the range we could, by fairly simple  trigonometry, find the unknown quantity, the height. 
 Andrews, G. A.: Airborne Radar Motion Compensation Techniques, Evaluation ofTACCAR, NRL  Report 7407, Naval Research Laboratory, Washington, D.C., Apr. 12, 1972. 
 Figure  8.28 illustrates the circuit or an eighl-elcme11t array that generates eight i11depe11dent beams. It  utilizes 12 directional couplers and eight fixed phase shifters. The Butler matrix has 2,, inputs  and 2,, outputs. 
 When biased in the reverse (nonconducting) state, the PIN diode resembles a low-loss capaci-  tor. It is essentially an insulator situated between two conductors and exhibits the paratlel-  plate capacitance determined by the dielectric of the intrinsic region. At microwaves, the  small-signal equivalent circuit of the PIN diode may be represented as a series RC circuit with  the capacitance determined by the area, thickness, and dielectric constant of the intrinsic  region. 
 China Civil Engin. J. 1999 , 32, 47–52. 
 15, pp. 452-466, 1958.  75. 
 Multiple Channels: Interferometry and Polarization.  Phase comparison  between two or more mutually coherent data sets leads to rich new possibilities, espe - cially including interferometry15 and polarimetry.41 This is particularly relevant to  space-based SARs, which have been and will continue to be rich sources of quantita - tive microwave measurements of a wide variety of surface features, enabled by these  multichannel capabilities. The following paragraphs provide only a glimpse into these  topics; the discussion is meant to whet the appetite of the reader and to provide leads  to the voluminous literature. 
 M. Phillips and D. W. 
 TIME RADAR DIGITAL SIGNAL PROCESSOR TYPICALLY REQUIRED THE DESIGN OF A CUSTOM COMPUT 
 Mutton, J. 0.: Advanced Pulse Compression Techniques, IEEE N AECON '75 Record, pp. 141-148. 
 The simulation results can interpret and evaluate the effects of radar look direction and wind ﬁeld conditions on SAR eddy imaging and provide guidance for interpreting eddy features in SAR images. Nevertheless, the proposed simulation method and results in this context are mainly focused on shear-wave-generated eddies. Other SAR imaging mechanisms of oceanic eddies, including ﬁlm mechanisms, thermal mechanisms, and ice mechanisms, need to be resolved through further research. 
 M. Bell, “The Hurricane Rainband and Intensity Change Experiment  (RAINEX): Observations and modeling of Hurricanes Katrina, Ophelia, and Rita (2005),” Bull.  Amer. 
 6 
  
 To select the proper length of the range chirp history and reconstruct a clean reference in range, a thresholding procedure was used; after the SVD decomposition, the reference signal power is much higher than the background noise, so this procedure reveals effective. In this case, the selected range time duration by the choice of a threshold at 10% of the signal peak value was efﬁcient. After the procedure described in the previous subsection, a clean range reference function was obtained. 
 The patterns shown in Fig. 11.17 are medians of RCS averages taken in cells 10° square. With modern data-collecting and -re- cording equipment, it is feasible to plot measured results at much finer intervals than are plotted in this figure. 
 Unless cor-  rection is made a rectangular target seen at a consider-  able distance on H2S equipment appears, not square,  but ‘thin.? As the run-up to the town is made it fattens  up to its true proportions. This is because at long range  the incident waves fall on distant objects from a direction  nearly parallel with the earth’s surface. Only the front,  facing walls of buildings thus give any return to the  radar receiver, and the rear walls are hidden from the  beam. 
 Oliner, A. A., and R. G. 
 Among the features that might be selected by range and azimuth are included the  choice of MTI or normal (log-CFAR) video, two STC control curves (one optimized for  terrain clutter, the other for sea clutter), the crossover range in switching from the upper to the  lower beam, fixed pulse-repetition period (for eliminating second-time-around clutter) or  variable pulse periods, different RF receiver gains, and sectors for transmitter blank~ng to  avoid RFI.  The digital target extractor provides the radar output in a form suitable for transmission  over narrowband telephone lines rather than require wideband microwave data links. Sliding-  window detectors determine the range and azimuth centroid of the radar returns using the  m-out-of-n detection criterion. 
 FM-CW Radar:  FM-CW Radar, Range and Doppler Measurement, Block Diagram and  Characteristics (Approaching/  Receding Targets), FM -CW alti meter, Multiple Frequency CW  Radar.    UNIT -III  MTI and Pulse Doppler Radar:  Introduction, Principle, MTI Radar with - Power Amplifier  Transmitter and  Power Oscillator Transmitter, Delay Line Cancellers – Filter Characteristics,  Blind Speeds, Double  Cancella tion, Staggered PRFs. Range Gated Doppler Filters. 
 In  this figure, the view is looking northward within the byte of Southern California. The  eastern terrain of San Clemente Island shows in the middle left of the figure. From  this current view, a ship with a particular air-search radar is located beyond (north) of  the island. 
 By introducing the applied magnetic field from within the waveguide via the single-turn  drive wire. the shorted-turn effect that limits the switching speed of the Reggia-Spencer phase  shifter is eliminated. This permits switching times of the order of microseconds. 
 Klystrons are producers of lower-power oscillations at  very high frequency. Their efficiency cannot very well  be high, for it is physically impossible to ensure that all  the electrons pass through the rhumbatron in both  directions. With the first types of Klystron developed a  radio-frequency output of not more than a tenth of a watt  is obtained from 10 watts input. 
 13.11 isthe desired signal. Since there aretwonulls perrevolution, the synchro must begeared upby?a ratio equal tohalf thenumber of markers. Inthefigure thenull lSused asaswitching signal foran oscillator offrequency approximately one megacycle per second. 
 7 Contours of constant doppler  frequency shift on a plane earth due to horizontal  motion FIGURE   16. 8 Geometry of complex fading  calculations ( after F . T. 
 REFLECTION MULTIPATH  MULTIPLE HOP PROPAGATION  AND  IONOSPHERIC FOCUSING MAY NEED TO BE INCLUDED IN THE EQUATION  DEPENDING ON THE SCENARIO OF INTEREST &ARADAY ROTATION REFERS TO THE VARIATION OF THE POLARIZATION OF THE SIGNAL INCIDENT ON THE TARGET AS A FUNCTION OF TIME AND DISTANCE  ARISING FROM ITS PROPAGATION THROUGH THE MAGNETIZED IONOSPHERIC PLASMA LINEARLY POLARIZED TRANS 
 132 SPECIFIC SYSTEMS ....... ..132 5.6 Simple Doppler System. 132 57 Range-measuring Doppler System. 
 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19   blind folio 19.50 ch19.indd   50 12/20/07   5:39:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 
 The range coverage, which totaled 47.5 nmi in the original  implementation, is divided into 11r, nmi intervals and the azimuth into !-degree intervals, for a  total of 365,000 range-azimuth resolution cells. In each !-degree azimuth interval (about  one-hair the beamwidth) ten pulses are transmitted at a constant prf. On receive, this is called a  coherent processing interval (CPI). 
 The radar antenna captures a portion of the echo  power. If the effective area of the receiving antenna is denoted A., the power P, received by the  radar is  The maximum radar range Rmax is the distance beyond which the target cannot be detected. It  occurs when the received echo signal power P, just equals the minimum detectable signal S,,, . 
 TIME INTENSITY AND RANGE 
 43, pp. 698-700, June, 1955.  19. 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.62  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 SELENE.  The Japanese lunar mission, SELENE,149 includes a 5 MHz Lunar  Radar Sounder (LRS)150 as one of its 14 payload instruments. 
 In the se trials, performance against schnor- kels was assessed using a dummy schnor kel on a submarine. Average detection ranges were 4.2 nmi at 500 ft and 5.2 nmi at 1000 ft, with similar results both withand without the discriminator. Figure 4.35 show the effects of the discriminator when ﬂying upwind, crosswind and downwind at 2000 ft, on range scale 30/10 and a moderate to rough sea (Beaufort 4 or 5). 
 Careful design is necessary  to minimize these sidelobes, just as antenna sidelobes should be minimized, in order  ch19.indd   23 12/20/07   5:39:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 
 I'he dome might also be fabricated from radome-like material using a honeycomb skin with  liglltweigtit printed-circuit phase shifts glued to the inner surface.  In a converitional phased array, a Linear phase gradient is applied across the aperture to  steer the bearn. However, a nonlinear phase distribution is required across the planar array of  the dome antenna. 
 It can be clearly seen in Figure 13that the rheological model results were closer to the leveling results. Table 3shows the quantitative comparison results of the root mean square error (RMSE) on the benchmarks. According to our calculation, the RMSE of linear model was ±10.7 mm, while the rheological model was ±5.0 mm, with an improvement of about 53%. 
 STATE DIGITAL RECEIVERS ARE USED -AGNETRONS  KLYSTRONS  TRAVELING 
 September. 1975.  MTIANDPULSE DOPPLER RADARlSI 7X.KrO~/C7ynsk i.J.:TheTwo-Frequency MTISystem. 
    
 sites requires a  knowledge of both the angle of arrival at the receiving site and the distance between transmit­ ter and receiver, as was indicated by Eq. (14.33). Any of the methods for measuring range with  a monostatic radar can be applied to bistatic radar, including pulse and FM-CW modulations. 
 high gain, good efficiency, stable operation, low interpulse noise, and  it can orerate with the modulated waveforms required of sophisticated pulse-compression  systems.  Description. A sketch of the principal parts of the klystron is shown in Fig. 
 The detection logic of these thresholds is also shown in Fig. 17.8. The blanking which occurs because of the main-guard comparison affects the detectability in the main channel, the extent of which is a function of the thresh- old settings. 
 Richards (ed.), Van Nostrand Reinhold Co., New York, 1969.  69. Plowman, J.C.: Automatic Radar Data Extraction by Storage Tube and Delay Line Techniques, J. 
 This means increased range cell migration (RCM) and severe coupling of range and azimuth [ 5]. The error of range cell migration compensation in the frequency domain will affect the imaging accuracy. The back projection algorithm can completely compensate the RCM in time domain, but it needs a lot of calculations [ 7]. 
 135.-Representative electrostatic cathode-ray tubes: (a) 5BP1, (b) 5CP1, (c) 3JPl, (d) 2.~Pl. Representative magnetic cathode-ray tubes: (e) 3HP7, (j) 4.APIO, (0) 5FP7, (h)7BP7, (i)12DP7. lfost ofthese tubes areavailable withother screen types.. 
 MTI RADAR  2.516x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 Selection of filters is based on clutter amplitude information stored in a clutter map.  The filters are selected on a range-cell by CPI basis. These FIR clutter filters have the narrowest rejection notches that can be obtained  with five pulses and the indicated level of fixed clutter rejection. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 7 .46  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 Very low single-scan false-alarm probabilities allow tracks to be formed quickly. 
 BACK REFLECTIONS TEND TO CANCEL EACH OTHER )F THE MATERIAL PROPERTIES ARE DOMINATED BY ELECTRIC EFFECTS  THE OPTIMUM LAYER THICKNESS IS CLOSE TO  K  AS MEASURED IN THE MATERIAL )F THEY ARE DOMINANTLY  MAGNETIC  THE LAYER CAN BE MUCH THINNER !S WITH THE SIMPLE 3ALISBURY SCREEN  $ØLLENBACH LAYERS CAN BE CASCADED IN ATTEMPTS  TO EXPAND BANDWIDTH  PRODUCING WHAT IS KNOWN AS  GRADED ABSORBERS &OR OPTIMUM  PERFORMANCE  THE INTRINSIC IMPEDANCE OF EACH LAYER TYPICALLY GETS SMALLER THE CLOSER THE LAYER IS TO THE METAL BULKHEAD OR BACKING LAYER &IVE OR MORE LAYERS HAVE BEEN USED IN THE COMMERCIAL PRODUCTION OF GRADED DIELECTRIC ABSORBERS  BUT COMMERCIAL 
 The hard-limiting,  however, causes cross-coupling between the azimuth and the elevation error-signal channels  and can result in significant error.21 Two-channel monopulse receivers have also been used by  combining the sum and the two difference signals in a manner such that they can be again  resolved into three components after amplification.1.22  The purpose in using one-or two-channel monopulse receivers is to ease the problem  associated with maintaining identical phase and amplitude balance among the three channels  oft he conventional receiver. These techniques provide some advantage in this regard but they  can result in undesired coupling between the azimuth and elevation channels and a loss in  signal-to-noise ratio.  The monopulse antenna must generate a sum pattern with high erficiency (maximum  boresight gain). 
 DOMAIN CHARACTERISTIC OF STANDOFF '02 SYSTEM -OREOVER  OTHER PHYSICAL PHE 
 F. T. Ulaby, M. 
 349-353,  March, 1968.  59. Walker, J. 
 More complex frequency processes  can be calculated analogously.   7.2.2  Range Resolution with FM CW Radar   The measurement period  € tmeas and the utilized bandwidth Δf are crucial for the range resol u- tion.  For targets, for which  € Δt<<T applies, nearly the complete period is available for the  measurement:   € tmeas≈T (7.10)  Two targets with the ranges  € R1 and  € R2 have a difference in frequency of:  € ΔfB=fB1−fB2=2Δf c0T⋅R1−R2=2Δf c0T⋅ΔR (7.11)  From the measurement period T comes the minimum resolvable beat frequency  € fBmin=1/T. 
 FIG. 12.5 Normal-incidence reradiation patterns of facets.INFINITE FLATFACETWIDE FACET NARROW FACET . FIG. 
 Hanczor and M. Kumar, “12-kW S-band solid-state transmitter for modern radar SYSTEMS,”  IEEE Transactions on Microwave Theory and Techniques , vol. 41, no. 
  
 One important parameter is the sharpening ratio of a DBS image, Ka, as the ratio of the Doppler bandwidth to the Doppler resolution, is given by [ 1]: Ka=Δfd/δfd=ΔfdTa (11) For DBS imaging, the velocity of the aircraft and the antenna beam width are always ﬁxed, which makes the Doppler bandwidth is ﬁxed at the given azimuth viewing angle. Since the CPI in one look direction satisﬁes Ta=NaTr, then Equation (11) can be rewritten as: Ka=ΔfdNaTr (12) From Equation (11), we can know that increasing the Doppler bandwidth, the coherent pulse number as well as the pulse repetition interval is a useful way to increase the sharpening ratio Ka. However, the sharpening ratio Kacannot be increased inﬁnitely. 
 J. Farrell and R. Taylor, “Doppler radar clutter,” IEEE Transactions on Aeronautical &  Navigational Electronics,  vol. 
 14.5  and 14.6 may be expressed entirely in terms of the known incident field values. The  problem then becomes one of evaluating the chosen integral and substituting the result  into Eq. 14.1 to obtain the RCS.FIGURE 14.17  The geometric optics RCS of a doubly curved surface depends  on the principal radii of curvature at the specular point. 
 It is possible to  scan tile stepped reflector to slightly wider angles than a simple paraboloid, but not as wide as  with some other scanning techniques. Disadvantages of this reflector are'the scattered radia-  tion from the stepped portions and the narrow bandwidth.  If only a portion of the spherical reflector is illuminated at any one time, much wider scan  angles are possible than if the entire aperture were illuminated. 
 For a particular graring angle  the two frequencies had to be obtained by reflying the aircraft along the same flight path.  Different grazing angles also required reflying the aircraft over the same area. Each point on  the curve is an average over 1 to 2 miles of ground track. 
 In this particular example, the relationship between the LO  frequency and the sampling rate will make the required NCO and the multipliers both  rather trivial because each required NCO output value is zero or ±1, and that special  case will be addressed shortly. For now, this architecture supposes that no such special  situation exists and that a general NCO/multiplier structure is needed. The design of FIGURE 25.10  Digital downconversion in the frequency domain 0 MHz75 MHz 1. 
  "  #. 
 Although multifunctional radars  have been deployed with mechanically scanned and electronically scanned antennas,  fully multifunctional radars use Active Electronically Scanned Arrays (AESA), which  contain a transmit-receive channel (T/R) for each radiator.1 The advantages of AESA  are fast adaptive beam shaping and agility, improved power efficiency, improved  mode interleaving, simultaneous multiple weapon support, and reduced observabil - ity.19–23 Perhaps half the cost and complexity of an AESA is in the T/R channels. That  said, however, the feed network, beam steering controller (BSC), AESA power supply,  and cooling subsystem (air or liquid) are equally important.9,11FIGURE 5.8  Strike fighter pulse doppler geometry7,9 ch05.indd   8 12/17/07   1:26:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 A 2D air-surveillance radar in one band used with a height-finder radar in another  band is a good method for achieving frequency diversity. Both radar bands have to be jammed  simultaneously if target location is to be denied.  548INTRODUCTION TORADAR SYSTEMS linearratherthansquare-law detectors areprderred. 
 111  11.8.3 Layering of the Outer -Surface Materials .............................................................. 111  12 Selected Areas in  Radar Signal Processing ..................................................................... 113  12.1 Constant False Alarm Rate (CFAR) ............................................................................. 
 Raisingthethreshold, however, canrequireasignificantly largersignal-to-noise, orsignal-to-Ij:lutter, ratioforagivenproba­ bilityofdetection. TrunkandGeorgel2wereamongthefirsttonotcthatsomething otherthantheconven­ tionalreceiver designshouldbeusedwhentheclutterpdfisnotRayleigh. Theyshowedthat themediandetector gavebetterperformance innon-Rayleigh clutterthantheconventional receiver (whichcanbecalledameandetector). 
 Perkins and T. A. Midford, “MMIC technology: better performance at affordable cost,”  Microwave J ., vol. 
 VIC on Sunderland aircraft, ARI 5634 As discussed in chapter 3, ASV Mk. IIIC was installed in Sunderland aircraft, with early CCDU trials taking place by August 1943 [ 19]. By June 1944 the ASV Mk. 
 The cause of these problemsappears to have been excessive drift of the CV208 magnetron and dif ﬁculty in retuning the receiver during ﬂight. Towards the end of the trial period ‘a new type of CV208 ’was received from TRE and this appeared to be much more stable in operation. The CV208 magnetron operated at 9370 Mc/s and had a typical peak power of 25 kW. 
  
 TION BETWEEN  R  IN D" AND  MF IS LINEAR EVEN IN THE PRESENCE OF MODERATE VEGETATION COVER   AS SHOWN IN &IGURE  4HE SLOPE OF THIS CURVE IS SOMEWHAT DIFFERENT WITH VEGETA 
 (These have been key components in long-range airborne radars that are required to detect . crossing targets immersed in clutter.) Nor are commercial instruments limited in their ability to measure phase noise at the larger offsets. They appear to have just two significant limitations. 
 14.20 and also inFig. 14.21 mounted ona750-va PU-16 inverter. The electrical connections are shown intheschematic diagram Fig. 
 Rev ., vol. 70,   pp. 938–946, 1946. 
 These  sidelobes are noise-like and are proportional to the clutter amplitude. They will not  cancel in the MTI canceler. The third source of sidelobes is high-frequency ripple in  the transmitter power supply. 
  
 17.26 is correct only if the temperature of the radar is  the same as that of the scene, which we assume; see Chapter 2 and Section 1.11  of Sullivan1):  EP G RtP A A = ⋅=Tx-avg Tx-avg Loss2 2 3 42 4λ σ πη ( ) ( )2 2 4 24σ π λRtA( )Loss⋅ (17.28) ch17.indd   16 12/21/07   2:43:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 
   PP n  *ANUARY . °{n  2!$!2 (!.$"//+    0 7 (ANNAN  h/PTIMUM FEEDS FOR ALL THREE MODES OF A MONOPULSE ANTENNA  ) 4HEORY ))  0RACTICE v )%%% 4RANS  VOL !0 
 Now Eiszero outside the range x=~d/2foradish with diameter dand sog(u) iszero forkd~<w.This corresponds, incidentally, tothe doppler frequency associated with themotion ofthe edge ofthedish or,what isusually about thesame thing, thenumber of beamwidths scanned per second. Although this calculation ismore complicated for separate transmitter and receiver dishes, etc., the important general conclusion stands—namely that, insofar asthe approximations used are good, the spectrum produced byscanning is definitely confined toafinite frequency range. Another lower limit onbandwidth issetbythe modulation due to fluctuation intarget cross sections. 
 TION THAT THE TIME 
 RESPONSE COEFFICIENTS TO BE ZERO &IGURE  A ILLUSTRATES THE COEFFICIENTS OF A TYPICAL  FILTER FOR THIS APPLICATION !LL OF THE ODD 
 Attenuation by precipitation. In tlic frequency range for which Rayleigh scatterirlg applies  (particles srnall in sire conil~itrcd with tlie wavclcngtli) tlic attenuation due to absorption is  give~t by  Attenuation (dB/krn) = 0.434 D~ Im (- K)  i ]  wlicrc tile sunimation is over 1 rnJ. D is the partlcle diameter in ccntimetcrs. 
 With range gating, the range measurement accuracy is on the order  of the range gate size (150 m/ µs), but this can be improved to a fraction of the gate  width by amplitude centroiding. Timeline Definitions.  Pulse doppler radar works on several different time  scales. 
 TIONS OF  SAY  LESS THAN  SQUARE METER &IGURE  SHOWS HOW EFFECTIVE 34# CAN BE AGAINST BIRDS 4HESE 00) PHOTOS WERE TAKEN WITH AN , BAND !232  AIR 
 (14.3), with T - 2R/c]. Hence there is an apparent rate of increase of l/R. The integral representing the clutter power ap- pears to diverge, but two factors so far ignored have a decisive influence at very short ranges. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.536x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 response in the specified direction. 
 TO 
 PLACEMENTS RANGING FROM  TO  KILOTONS &IGURE  SUMMARIZES THE GENERAL 2#3 LEVELS OF THE WIDE VARIETY OF TARGETS  DISCUSSED IN THIS SECTION  WITH THE 2#3 OF A METALLIC SPHERE SHOWN AS A FUNCTION OF ITS VOLUME FOR COMPARISON 4HE ORDINATE IS THE 2#3 IN SQUARE METERS   AND THE ABSCISSA IS  THE VOLUME OF THE TARGET IN CUBIC FEET "ECAUSE THE CHART IS INTENDED ONLY TO DISPLAY THE WIDE RANGE IN 2#3 THAT MAY BE ENCOUNTERED IN PRACTICE  THE LOCATIONS OF TARGETS ON THE CHART ARE APPROXIMATE AT BEST 7ITHIN GIVEN TARGET CLASSES  THE 2#3 MAY BE EXPECTED TO VARY BY AS MUCH AS  OR  D"  DEPENDING ON FREQUENCY  ASPECT ANGLE  AND SPECIFIC TARGET CHARACTERISTICS 2EADERS SEEKING MORE EXPLICIT DETAIL THAN THIS SHOULD CONSULT REFERENCED MATERIAL AT THE END OF THIS CHAPTER&)'52%   -EASURED 2#3 OF A ONE 
 DIFFERENCE ESTIMA 
 RADIX BUTTERFLIES PROVIDE SOME COMPUTATIONAL SAVINGS &IGURE  SHOWS A RADIX 
 Operator control of the pulse length effec - tively switches in different choices of reactive components. The discharge of the PFN  is controlled by a high voltage switch, which is often a silicon-controlled rectifier;  thyristors and FETs are also used. FET modulators are sometimes driven directly by  a pulse input rather than a PFN. 
 The probability that the value of x lies within the finite rangz  from xl to x2 is found by integrating p(x) over the range of interest, or  X2  Piobability (x, < x < x2) = 1 p(x) dx  XI  By definition, the probability-density function is positive. Since every measurement must yield  some value, the integral of the probability density over all values of x must be equal to unity; .j that is,  The average value of a variable function, +(x), that is described by the probability-density  function, p(x), is  This follows from the definition of an average value and the probability-density function. The  mean, or average, value of x is  t Probabilities are sometimes expressed in percent (0 to 100) rather than 0 to 1. 
 flection from the input aperture (which now has a mismatch corresponding to a scan of 2 sin 6) and will be phase-shifted once again to produce a beam at the radiating aperture in the direction 3 sin 9. Additional reflections acquire twice the original phase shift for each round trip, resulting in radiated beams at positions of 5 sin 6, 7 sin 9, etc. The magnitude of these beams is approximately equal to the product of the voltage reflection coefficients if the number of bounces is taken into account. 
 Another complicating factor is tlie breaking of waves and the generation of spray, foam,  or whitecaps which have an effect on the radar backscatter. The presence of swell waves  alorig with the wind-driveti sea can also affect the radar backscatter. Still another important  factor when attempting to understand the effect of the wind on sea clutter is the difficulty  C in acct~rately estimating witid speed at sea.6  Effect of pulse width. 
 The development ofmicrowave airborne radar systems forced the development ofthe science and art ofradome design. Itresulted in amplification oftheelectrical theory forradomes through which theradar beam passes athigh angles ofincidence. Plywood, first used forradome construction, gave way tomore satisfactory synthetic materials; and aerodynamics, atfirst ignored, was given consideration inthe design. 
 The radar cross section of a complex target such  as an aircraft can vary greatly with a change in frequency. At some frequencies, the  radar cross section will be small and at others it will be large. If a radar operates at a  single frequency, it might result in a small target echo and, therefore, a missed detec - tion. 
 MOUNTED 643 ANTENNA REQUIRES A SHARP CUT 
 The latter signal acts to deﬂect theelectron beam radially from the center of the CRT screen (PPI) to form atrace of the radial movement of the electron beam. This radial movement ofthe electron beam is called the SWEEP or TIME BASE. While the termstrace and sweep are frequently used interchangeably, the term trace isdescriptive only of the visible evidence of the sweep movement. 
 CHANNEL RECEIVER CALIBRATION v $34/  4ECHNICAL 2EPORT $34/ 
 . £x°ÎÈ  2!$!2 (!.$"//+  .UMERICAL -ETHODS  7ITH RAPID INCREASES IN COMPUTER SPEED  IT HAS BECOME  PRACTICAL TO SOLVE CERTAIN SCATTERING PROBLEMS BY NUMERICAL METHODS  THEREBY SIDE 
 (a1m (c)TRACKING RADAR161 M (J (d)Angle Figure5.7Monopulse antenna patterns anderrorsignal.Left-hand diagrams in(a-c)areinpolarcoor­ dinates; right-hand diagrams areinrectangular coordinates. (a)Overlapping antenna patterns;(b)sum pattern;(c)dilTerence pattern;(d)product (error)signal. anerrorsignalwhosemagnitude isproportional totheangu!ar errorandwhosesignis proportional tothedirection. 
 POLAR COMPONENT  FROM SLOT TO SLOT  CAUS 
 Fourth, wenow have two design frequencies, f~and j,,and itisamatter ofgreat importance which isthe greater. If.f~<<~,, asthe diagram above implies, the apparatus works asdescribed. If-f,<f~,,the opera- tion isthe same inprinciple but signals will bewithin the doppler taken this beat will completely dominate thetarget signals. 
 More than one diode may be used to provide  greater attenuation or larger bandwidth.  Before the introduction of the solid-state diode limiter, a low-power gas TR-tube, known  as a protector TR, was often used as added protection for the receiver. Jt was placed between  the receiver port of the duplexer and the receiver to safeguard against random pulses from  nearby radar equipments which were too weak to fire the conventional TR tubes in the  duplexer, but strong enough to damage the receiver. 
 IEEE T rans. Geosci. Remote Sens. 
 20.3c. Another effect is the introduction of errors in the radar measurement of elevation angle. In the tropospheric portion of the atmosphere, the index of refraction n is a function of such meteorological variables as temperature, pressure, and water vapor and can be represented by30 („ - ,) x 10« - N = Z^E + H^£ (20.4) where T = air temperature, K; p = barometric pressure, in millibars; and e = partial pressure of water vapor, in millibars. 
 ... ..... 442 12.5 Second Detector ... 
 PROCESSING CIRCUITRY INTO SUPPRESSING THE ACTUAL TARGET RETURN 7HAT THE RADAR CAN DO AGAINST $%#- IS DISCUSSED LATER SEE 3ECTION )N THE DEPLOYMENT OF %#-  SEVERAL CLASSES CAN BE SINGLED OUT  )N THE STAND 
 11, pp. 1766-1777, August 1972. 8. 
 Tomlinson: Distributed Array Radar, IEEE Trans., vol. AES-19, pp. 831-839, 1983. 
 214INTRODUCTION TORADAR SYSTEMS 6.8MODULATORS Thefunction ofthemodulator istoturnthetransmitting tubeonandofftogenerate the desiredwaveform. Whenthetransmitted waveform isapulse,themodulator issometimes calledapulser.EachRFpowertubehasitsownpeculiar characteristics whichdetermine the particular typeofmodulator tobeused.Themagnetron modulator, forinstance, mustbe designed tohandlethefullpulsepower.Ontheotherhand,thefullpoweroftheklystron and thetraveling-wave tubecanbeswitched byamodulator handling onlyasmallfractionofthe totalbeampower,ifthetubesaredesigned withamodulating anodeorashadowgrid.The crossed-field amplifier (CFA)isoftencathode-pulsed, requiring afull-power modulator. Some CFAsared-coperated, whichmeanstheycanbeturnedonbythestartoftheRFpulseand turnedoffbyashort,low-energy pulseappliedtoacutoffelectrode. 
 The first local oscillator, generally referred to as a stable  local oscillator (STALO) , typically has the greatest effect on receiver-exciter stability;  however, when evaluating the overall performance, other contributions should not be  neglected. Advances in state-of-the-art STALO oscillator performance and the strin - gent clutter cancellation requirements of modern radars means that the phase noise of  all oscillators and timing jitter of A/D converter and D/A converter clocks and T/R  strobes may be significant. The short-term stability requirements of the STALO are generally characterized  by device noise relative to carrier (dBc), specified in terms of a phase noise spectrum  and measured in the frequency domain. 
 NOISE RATIO ASSOCIATED WITH FREQUENCY DOMAIN  WEIGHTING AS FOR THE ,&- WAVEFORM  IS ELIMINATED )F A SYMMETRICAL &- MODULATION IS USED &IGURE  A  WITH TIME 
 The  lower bandwidth helps to reduce the mean noise level, whereas the shallower incident  angle helps to maintain range resolution with smaller radiated pulse bandwidth. Clementine , one of the first “faster better cheaper” missions, had primary objectives  including laser altimetry and optical surface mapping of the Moon as well as technol - ogy demonstration. The main payload instrumentation was comprised of four optical  cameras, including one with a laser altimeter. 
 1970.  26. Trunk, G. 
 In principle, the elements of an array located on any non planar surface can be made to  radiate a beam in some given direction by applying the proper phase, amplitude, and polariza­ tion at each element. In practice, however, it is difficult to control the beamshape and obtain  low sidelobes from an arbitrary surface, especially if the beam is electronically scanned.  Furthermore, the mechanisms for feeding the elements and steering the beam of a conformal  array, as well as the generation of the phase-shifter commands, are generally more complicated  than those of a planar array. 
  
 13.4 by the obliquity factor38,39 1/2 (1 + cos q ). This gives  Ea a( ) ( c os)sin[( / ) sin] ( / ) sinq qq q= +121π λ π λ (13.6) For closely spaced elements, the obliquity factor is very similar to the amplitude  pattern of a well-designed (matched) radiating element, cosq, for values up to  some 60 or 70 °. At greater angles, the element pattern has values that are greater than  those given by cosq and that are a function of the total number of elements.40 Scanned Linear Arrays . 
 The same process is performed in the opposite direction to match mission image change areas in the reference image. Figure 5illustrates this step. Figure 5. 
 , 
 ING AWAY FROM THE CHAMBER CENTERLINE    %VEN TARGETS OF MODEST SIZE CANNOT BE MEASURED AT THE FAR 
 10–19, 1992, translation of Radioteknika I Electronika . 140. R. 
 11.161  extend, in this instance, from - B/2 to + B/2 instead of from - co to + oo. Thus the efTective  where Si x fs the sine integral furiction defined by (sin u)/u du. As Br -+ m, the product  p2r2 4 2Br. 
 457 TYPIC.AL RECEIVERS ....... .. ... 
 Skolnik (ed.),  McCraw-Hill Book Co., New York, 1970.  83. Hill, R. 
 (The original TDWR waveform was constant  PRF during each antenna rotation, and processing was done with elliptic filters.) They  then modified the system “…to achieve 65-dB clutter suppression using a nearby  water tower for a target.”52 The TDWR uses a klystron transmitter tube. Typical phase  pushing for a klystron due to modulator voltage change is 10° for 1% delta-E/E. The  stability budget allocated a 75-dB limit on improvement factor to the transmitter, and  this required that the rms pulse-to-pulse power supply voltage variation be less than  1 part in 100,000. 
 RADARSAT-1 looks to the right side of the  orbit plane, which gives it access to the Canadian Arctic up to the North Pole. Twice  during its mission, the spacecraft was yawed 180 ° for several weeks, which enabled  full coverage of Antarctica. The resulting data were merged to yield the first high- resolution imagery of the whole continent,18 and over several regions, repeat-pass  coverage supported interferometric SAR measurement of Antarctic glacial flow rates. 
 ERS IS BECAUSE THE TRANSMIT PULSE SCATTERS POWER FROM ALL SCATTERERS IN THE  CS PULSE  VOLUME NOT JUST A SINGLE POINT TARGET  THEREBY INCREASING THE RADAR CROSS SECTION OF THE WEATHER SCATTERER 02&S FOR METEOROLOGICAL RADARS  RANGE FROM AS LOW  AS SEVERAL HUNDRED  S n FOR LONG 
 With care indesign anduse ofhydrogen thyratron or mercury-sponge type ofen- closed gaps, time jltter of 0.02 usecorlessobtainable Less, permitting smaller size andweight Better than ahard-tube palser designed formaximum effi- ciency since (AP/P) output =2(AV/v) input forline- type pulser, independent of design load may also display occasional short-circuit and open-circuit conditions which must beallowed forinthe pulser design. Confining our attention tothemagnetron, wenote inFig. 10.29 that itdisplays adynamic impedance attheoperating point ofonly 430 ohms, even though the V-1 impedance ratio is1480 ohms there. 
 24.3 and 24.4 to the simple case of one auxiliary antenna and one  jammer, the following results are found:  ˆ{ * } {| | } | |W= = =−E V V E VJCRM A A2 21 1∆ρρ (24.5) It is noted that the optimum weight is related to the correlation coefficient r between  the main signal, VM, and the auxiliary signal, VA; high values of the correlation coef - ficient provide high values of JCR. The problem of implementing the optimum-weight set (Eq. 24.3) is essentially related  to the real-time estimation of M and R and to the inversion of M. 
 S. Williams: “Radar return from the vertical for ground and  water surface,” Sandia Corporation, Albuquerque, NM, 1960. 127. 
 Substituting  into Eq. (14.22) G, = G, = G = nZ/O,O,, where 0, = azimuth beamwidth; and T, = rS0,/OT, r, =  revisit time (scan time) and 0, = total azimuth angle coverage, we get  Lumpirig into a single constant K the constants in this equation and the parameters assumed  to be given (including I),.) or not under the control of the radar designer, we get  Thus a measure of the performance of an HF surveillance radar is the ratio of the average  power divided by the azimi~tli beamwidth. When comparing the performance of two radars  with different antenna heights as well as dimerent widths, a measure of relative performance is  Measure of performance = Pa, wh2 (14.26)  where w = antenna width and It = antenna height. 
 Ohio), pp. 286-290, 1958.  61. 
 In  general, nighttime noise will be greater than daytime noise for skywave illumination  of a selected range. This is evident in Figure 20.20, recorded at time zone UT + 9½.  The general trends of atmospheric noise in other seasons are similar to those in winter. 
 Beard. C. I., D. 
 \K 
 REINFORCED PLAS 
 Toaccomplish this, ana-fwave ispassed through atwo-phase synchro onthe scanner and atwo-phase differential synchro controlled byacompass sothat the two resulting signals have amplitudes proportional tosin 0and cos @respectively, where 6isthe scanner orientation with respect totrue north (Sec. 13.4). Each ofthese signals ispassed through aphase-sensitive rectifier keyed bythe audio oscillation inorder todevelop the slowly varying voltages necessary tocontrol the sine and cosine delay circuits (Sec. 
 2.2MINIMUM DETECTABLE SIGNAL Theabilityofaradarreceivertodetectaweakechosignalislimitedbythenoiseenergythat occupies thesameportionofthefrequency spectrum asdoes'thesignalenergy.Theweakest signalthereceivercandetectiscalled.theminimum detectable signal.Thespecification ofthe minimum detectable signalissometimes difficultbecauseofitsstatistical natureandbecause thecriterion fordeciding whether atargetispresentornotmaynotbetoowelldefined. Detection isbasedonestablishing athreshold levelattheoutputofthereceiver.Ifthe receiveroutputexceedsthethreshold, asignalisassumed tobepresent.Thisiscalledthreshold detection. Consider theoutputofatypicalradarreceiverasafunction oftime(Fig.2.1).This mightrepresent onesweepofthevideooutputdisplayed onanA-scope. 
 SIZE DISTRIBUTION  ALTHOUGH "URROWS AND !TTWOODS STUDIES SEEM TO INDICATE THAT A CERTAIN MOST PROBABLE DROP 
 At any position along  the x-axis the distance z is also given by  z x x zi i= − + ( )02 02 (21.11) 0−18−36−54−72 FIGURE 21.12  Electric field plot on a vertical cut plane after the main ground  reflection  (Courtesy IEE ) ch21.indd   17 12/17/07   2:51:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 24.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 24.6 ANTENNA-RELATED ECCM Because the antenna represents the transducer between the radar and the environ - ment, it is the first line of defense against jamming. 
 Skolnik.  McGraw-Hill Book Company. New York, 1970. 
 On-axis tracking,  as compared with trackers with a target lag, improves the accuracy by reducing the coupling  between the azimuth and elevation angle-tracking channels, by minimizing the generation of  cross polarization and by reducing the effects of system nonlinearities.  The processes that constitute on-axis tracking incliide (I) the use of adaptive tracking  whose output updates a stored prediction of the target trajectory rather than control the  antenna servo directly, (2) the removal by prior calibration of static and dynamic system  biases and errors, and (3) the use of appropriate coordinate systems for filteriqg (smoothing)  the target data.  The radar's angle-error signals are smoothed and compared to a predicted measurement  based on a target-trajectory model updated by the results of previous measurements. 
 B.. M. J. 
 An accuracy of 1% is required (but not better than 30 meters). A bearing  scale around the periphery of the operational display must be visible. This scale can  help users determine the ship’s direction from viewing the heading line  (HL), which  has to be shown on the display; only temporary extinguishing of the HL is permitted. 
 E.: Eliminating Transmitted Clutter in Doppler Radar Systems, Microwave J., vol. 18,  pp. 47-50, November, 1975. 
 Beam Scan-on-Scan.  When high-gain, narrow-beam scanning antennas are  used by both transmitter and receiver in a bistatic surveillance radar, inefficient use  is made of the radar energy because only the volume common to both beams can be  observed by the receiver at any given time. Outside this common beam volume, targets  are lost to the receiver. 
 48. B. L. 
 [ CrossRef ][PubMed ] 21. Berizzi, F.; Corsini, G. Autofocusing of inverse synthetic aperture radar images using contrast optimization. 
 (ILL   2 +LEMM  0RINCIPLES OF 3PACE 
 However, the vast majority of transmissions are not the result of any interroga - tion, as it mainly operates as a broadcast system, based around a Self Organizing Time  Domain Multiple Access  (SOTDMA) communications protocol. The communications  link, including the SOTDMA definition, is defined by the ITU.27 Ships automatically  transmit current navigational data and other information on VHF marine-band chan - nels assigned for AIS use. The transmitted information is received by other ships and  also by shore stations, such as coastal authorities and VTS facilities. 
 The simple expression of Eq. (4.36) shows that the  spread in the clutter spectrum is a function of the angle 8 betwC?Cn the velocity vector of the  moving platform and the antenna beam-pointing direction. It also depends on the wavelength. 
 Bingham, “Greenland snow accumulation esti - mates from satellite radar scatterometer data,” J. of Geophysical Research , vol. 106(D24),  pp. 
  AND THE 3 
 TO 
 2'0/ !NTI 2ANGE 'ATE 0ULL /FF !2- !NTI 2ADIATION -ISSILE ! 
 The  slit is offset from the origin because of the de bias that had to be added to the signal at the  input to the CRT in order to record on film. If the slit were placed on the optical axis,  the presence of the de bias will cause a degraded image because the energy from the bias  overlaps the desired image. This is avoided by placing the input signal on a residual carrier  r  Conical  lens  Signal hislory film  and weighting lronsporancy  Figure 14.6 Optical processor for synthetic aperture radar. 
 PLANE SEGMENTS 2ADAR RETURN IS ASSUMED TO OCCUR ONLY FOR FACETS ORIENTED NORMAL TO THE RADAR NORMAL ORIENTATION IS REQUIRED FOR BACKSCATTER SO THAT THE REFLECTED WAVE RETURNS TO THE SOURCE  4HUS  IF THE SLOPE DISTRIBUTION OF SUCH FACETS IS KNOWN  THE FRACTION NORMAL TO A GIVEN DIVERGING BEAM CAN BE ESTABLISHED  AND FROM THIS THE RETURN CAN BE OBTAINED 'EOMETRIC OPTICS ASSUMES ZERO WAVELENGTH  AND SO THE RESULTS OF SUCH A THEORY ARE WAVELENGTH 
 ¤ ¦¥³ µ´   SPM  OR  SPM 6 AX    WHERE 6X AND A ARE IN CONSISTENT UNITS 4HIS VALUE IS LOWER THAN ONES DERIVED BY OTHER  AUTHORS  (OWEVER  IT AGREES WITH MORE EXACT ANALYSIS OF ANTENNA RADIATION PATTERNS  AND EXPERIMENTAL DATA ANALYZED BY & 3TAUDAHER ! MORE EXACT VALUE OF THE PARAMETER  RPM MAY BE OBTAINED BY MATCHING A TWO 
 A, and B, and C represent  signal plus noise. ,4 arid B would be valid detections, but C is a missed detection.  the cross correlation between the received waveform and a replica of the transmitted  waveform. 
 MADE  SURFACES SELDOM ARE SO SIMPLY DESCRIBED 4HE THEORIES FOR VEGETATION AND OTHER VOLUME SCATTERS HAVE MORE PARAMETERS &OR NEAR 
 NOISE RATIO AT THE INPUT TO THE PROCESSOR  TO THE CLUTTER 
 Figure 17.2 presents a comparison of RAR and SAR. FIGURE 17.2  Comparison of RAR and SAR: The crossrange resolution (peak- to-first-null of antenna pattern) of a SAR is one-half that of a real aperture radar  (RAR) of the same aperture diameter. ( Courtesy of SciTech Publishing, Inc .) ch17.indd   9 12/17/07   6:48:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Advantage can be taken of this difference to enhance the target-to-  clutter ratio when the clutter background is precipitation. This is accomplished by utilizing a  radar with circular polarization or with crossed linear polarization.  A circularly polarized wave incident on a spherical scatterer is reflected as a circillarly  polarized wave with the opposite sense of rotation and is rejected by the antenna that orig-  inally transmitted it. 
 (4.19) and (4.22) into Eq. (4.21) and assuming that <I,~ l/T, the clutter  attentuation is f; Wo exp (-f2/2a;) df CA = ~-·:::....:;._----------'---- J0 W0 exp (-f2/2a;)4 sin2 nf T df  0.5 (4.23) . MTI AND PULSE DOPPLER RADAR 133  If the exponent in the denominator of Eq. 
 pp. 47 58. Octohcr. 
 2Theuseofproximity fuzes eliminates thisstep. 213. 214 THEEMPLOYMENT OFRADAR DATA [SEC. 
 The coverage regions numbered 1–5 correspond to skywave radar missions as follows: 1,  air route monitoring; 2, barrier surveillance; 3, strategic waterway monitoring; 4, ballistic missile launch  detection; and 5, remote sensing and hurricane tracking. The sector designated 6 is representative of HF  surface wave radar coverage. ch20.indd   4 12/20/07   1:15:25 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 l02. Skolnik, M. I.: Large Antenna Systems, chap. 
 W. and H. K. 
 'ENERATION 3OLID 
 25.2.  134. Nichollsr R. 
 BASED RADAR ALTIMETRY )T IS KNOWN MORE COMMONLY  TO MOST RADAR ENGINEERS AS THE 3TRETCH TECHNIQUE&)'52%   4HE 'EOSAT RADAR ALTIMETER 4HE NADIR 
 Power devices in GaAs are commonly built as metal- semiconductor field-effect transistors (MESFETs), so called because the gate metal is deposited directly onto the semiconductor channel region, forming a Schottky barrier. Power FETs that are fabricated on GaAs exhibit substantially higher frequency performance than similar devices fabricated on silicon because GaAs has a higher electron bulk mobility and a greater maximum electron drift velocity than silicon. In addition, the electron mobility in epitaxial GaAs ap- proaches the bulk value; hence GaAs FETs exhibit lower parasitic series resis- tances and higher transconductances than silicon FETs with similar geometries. 
 € PR=PTGT⋅1 4πRT2⋅σB⋅1 4πRR2⋅λ2 4πGR =PT⋅GTGRλ2 (4π)3RT2RR2σB (3.17)  Here meaning:   € PR=receiver power   € PT=transmitter power   € RT=distancefrom thetransmitter tothetarget  € RR=distancefrom thereceiver tothetarget   € σB=bistatic radar cross−section ofthetarget  € GT=transmitter gain   € GR=receiver gain   For the analysis of the receiver signal the direct, coherent reception of the transmitter signal ( il- luminator) is necessary.  From the propagation time and the directions the Radar picture is gener- ated with relatively elaborate trigonometry.   Of interest is particularly the use of available transmitters (e.g. 
 DISTRIBUTED WITH ZERO MEAN AND CONSTANT VARIANCE  R  BUT WITH OCCASIONAL OUT 
 BAND 7ARLOC WAS INSTALLED IN A VAN AND WAS USED FOR VARIOUS EXPERIMENTS 4HE 7ARLOC RADAR WAS ABOUT THREE ORDERS OF MAGNITUDE MORE CAPABLE THAN MOST PREVIOUS RADARS USED FOR MILLIME 
 The first four traces represent successive sweeps ofA-scope. The last three traces show thecanceled signals. scheme isto delay the signals of Sweep 1forawhole repetition period and then subtract them from the signals ofSweep 2. 
 It rotates a 13.2-ft-square array at 5 to 10 r/min while generating a stack of three receive beams covering 21° in elevation. The array is divided into three vertical sections. Each section of the array then generates its own beam, which is phase-steered over a designated section of the elevation coverage.15 . 
 This page has been reformatted by Knovel to provide easier navigation. xxii     Contents   15. MTI Radar   ................................................................. 
 THE 
 Van Vleck, J. H., and D. Middleton: A Theoretical Comparison of the Visual, Aural, and Meter  Reception of Pulsed Signals in the Presence of Noise, J. 
 Itis easy toproduce such abeam bymeans ofanantenna whose effective aperture iswide inthedirection inwhich the beam istobenarrow and narrow inthe direction inwhich the beam istobebroad. The con- nection given byEq. (1)between aperture and gain still holds, implying that byreducing the vertical dimension ofthe antenna aperture (in Fig. 
 Batch Processor. The batch processor (Fig. 8.3e) is very useful when a large number of pulses are in the 3-dB beamwidth. 
 Random phase noise riding on a large signal can mask  weak target returns. The object is to specify system phase noise so that it is well below  the thermal noise when a large signal at the A/D saturation level is present in the  receiver. (A signal at A/D saturation is the largest signal that can be linearly processed  by the radar receiver.) Then the radar sensitivity is limited by thermal noise (always  present) plus a small increase in the total noise level caused by the phase noise. 
 One half ofthis tube isused inacircuit tolengthen the duration ofbeacon reply pulses and sogive abrighter spot ontheCRT screen. Ontherise ofthepulse thediode conducts, and theinput capacity ofthe second tube ischarged rapidly. When the amplitude ofthe pulse starts todecrease, the diode nolonger conducts, and the charge onthe grid ofthe second tube leaks away S1OW1 ythrough a2.2-megohm resist or. 
 4(% 
 TRIBUTES TO IMPROVED 3.2  BUT AT THE COST OF INCREASED AVERAGE DATA RATE $ATA RATE CAN BE DECREASED BY hPRE 
 O X  vY O T   ii bMXR bR ivtmX Figure 4. Single beam signal model. 13. 
 Thethickness ofthelensisagainincreased inthedirection oftheaxisaccording tothelensdesignuntilthepathlengthinthedielectric isoncemore360°,atwhichtime another stepmaybemade.Theopticalpathlengththrough eachofthezonesisone wavelength lessthanthenextouterzone. Although zoningreduces thesizeandweightofalens,itisnotwithout disadvantages. Dielectric lensesarenormally wideband; however, zoningresultsinafrequency-sensitive device.Another limitation isthelossinenergyandincrease insidelobe levelcausedbythe shadowing produced bythesteps.Theerfectofthestepsmaybeminimized byusingadesign withlargefiD.ontheorderof1ormore.Evenwiththeselimitations, astepped lensisusually tobeprererred because ofthesignificant reduction inweight. 
 The 14 ft (4.3 m) by 8 ft (2.4 m) reflector is an offset paraboloid  fed from a 12-element vertical line-source. The uppermost feedhorn is located at the focal point  of the paraboloid. The azimuth beamwidth is l.6° and the vertical beamwidth is 4° with  cosecant-squared shaping from 6° to 30°. 
 First, although theclutter may, inprinciple, beeliminated byinfinite attenuation filters t~mmi tothe repetition frequency and multiples thm-eof, the nlmll>er offilters req~lired i<(ofthe ordrr ofr~r, and ifthis number islmgc thesystem may beimpr~ctical. This limitation appeai-s tobefundamental and arise.+ insimilar form inallother .s3-stems, But cl-en ifl\-eneglect the multiplicity ofthe filterx, there isconsiderable doubt whethrr practical means offreq~leney modulation can bede~-ised that will make succes.sire modulation cycles asnearly identical asis necdecl forfiltering outreally serious clllttcr. Second, asare. 
 Mutual coupling, therefore, causes the actual radiation pattern to differ  from that which would_ be predicted from an array of independent radiators. Thus to achieve  the benefits from full control of the aperture illumination of a phased array, mutual coupling  among the elements must be properly taken into account.  Most analyses of mutual coupling are concerned with the change in impedance at the  input to the element.74-77 It is important to know how the impedance changes in order to  properly match the impedance of the transmitter and the receiver to the radiator. 
 CENTERED%QS  TO  IN POLAR COORDINATES3TATE PROPAGATION IS LINEAR NO PSEUDO 
 On the other hand, for fo = 0.5 GHz (UHF, l = 0.6 m), tA = 167 sec = 2.8 min and  B/fo = 0.3. Such a high fractional bandwidth (an ultra-wideband SAR ) presents challenges  in designing hardware components, such as antennas, that are reasonably linear over the  full frequency range.57 Furthermore, the long aperture time presents motion-compensa - tion challenges, and the wide real-beam angle adds to processing difficulties, very likely  requiring Range-Migration Algorithm (RMA) processing (Section 17.3). In addition, for  calculating crossrange resolution, the small-angle approximation no longer holds. 
 BANDWIDTH CHIRP  WAVEFORMS THAT CANNOT BE GENERATED DIRECTLY USING AVAILABLE $$3 DEVICES &REQUENCY MULTIPLIERS OPERATE AS SHOWN IN &IGURE   BY MULTIPLYING THE PHASE OF THE INPUT SIGNAL BY THE INTEGER MULTIPLICATION FACTOR  - 3INCE IN PRACTICE THE PROCESS TYPICALLY  INCLUDES SOME FORM OF LIMITING  THE OUTPUT AMPLITUDE  !T  GENERALLY HAS A LOWER AMPLI 
 -   2 # %MERSON  h3OME PULSED DOPPLER -4) AND !-4) TECHNIQUES v 2AND #ORPORATION 2EPT   2 
 Any use is subject to the Terms of Use as given at the website. Radar Receivers. 6.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 RF STC prior to any amplification, it can be set to full attenuation to minimize exter - nal interference with minimal (and predictable) effect on system noise temperature. Most  radars employ amplifiers prior to STC, so they cannot attenuate external interference with - out affecting the noise level. 
 The  availability of dual-channel radars with built-in-test equipment and fault isolation has been  demonstrated to be considerably greater than 99 percent. High availability also requires that  spare parts be at hand when needed and that maintenance personnel be experienced and  motivated. In diplex operation the two frequencies are radiated on orthogonal polarizations. 
 42 
 Barker et al., Modern Microwave and Millimeter-Wave Power Electronics , New York: IEEE  Press and Willey Interscience, 2005, p. 108.  5. 
 Pulsed magnetrons vary from a 1-in3, 1-kW peak-power beacon magnetron up to several megawatts peak and several kW average power, and CW magnetrons have been made up to 25 kW for industrial heating. All commercial marine radars have used magnetrons. Magnetron transmitters have been widely used for moving-target indication (MTI) operation, typically allowing 30 to 40 dB of clutter cancellation. 
 X Radar against Schnorkel, Army Operational Research Group, Report No. 288, Feb/March 1945 (TNA WO 291/266) [6] ASV Mk. VIB and C, Air Publication 2890 M & N, vol 1, Ministry of Supply, December 1947 (TNA AIR 10/4941) [7] A.S.V. 
 43. pp. 877 878. 
 40-45, December, 1955.  8. Roberts, W. 
 MITTER  MECHANICALLY SCANNING ANTENNAS PRODUCE A MODULATION THAT IS PREDOMINANTLY !- 4HE COMBINED EFFECT IS THE SUM OF THE RESIDUE POWERS PRODUC ED BY EACH COMPO 
 These are examples of scatterers whose radar cross sections are  greater at millimeter wavelengths than at microwaves since they are generally in the resonance  region (Fig. 2.9) at millimeter wavelengths, but in the Rayleigh region at microwaves (where  the cross section varies as tlie fourth power of the frequency). Another advantage of the short  wavclerlgths is that a dopplcr-frequency ~iieasuretnent of fixed accuracy gives a more accurate  velocity measurement than at lower frequencies. 
 73. Carpentier, M. H.: "Radars: New Concepts," Gordon and Breach, New York, 1968, sec. 
 Atmospheric andurbannoise.Asinglelightning strokeradiates considerable RFnoise power.Atanyone moment thereareanaverageof1800thunderstorms inprogress indifferent partsoftheworld.Fromallthesestormsabout100lightning flashestakeplaceeverysecond.53 Thecombined effectofallthelightning strokesgivesrisetoanoisespectrum whichis especially largeatbroadcast andshort-wave radiofrequencies. Noisethatarisesfrom lightning-stroke radiation iscalledatmospheric noise(nottobeconfused withnoiseproduced byatmospheric absorption asdescribed previously). Thespectrum ofatmospheric noisefalls ofrapidlywithincreasing frequency andisusuallyoflittleconsequence above50MHz.54 Henceatmospheric noiseisseldomanimportant consideration inradardesign,except,per­ haps,forradarsinthelowerVHFregion. 
 SCATTER 2#3 ROLLOFF  WHEN O  
 L.A.DUBRIDGE. Yii. Preface THEearliest plans fortheRadiation Laboratory Series, made inthefall of1944, envisaged only books concerned with the basic microwave and electronic theory and techniques that had been sothoroughly devel- oped during thewartime work onradar. 
 COMBINED CONFIGURATION WHEREIN EACH RADIATING ANTENNA ELE 
 125-146, 1985. 51. Bonewitz, J. 
 It has  also allowed the ready incorporation of the quadrature channel for elimination of blind  phases. In short, digital MTI has allowed the radar designer the freedom to take advantage of  the full theoretical capabilities of doppler processing in practical radar systems.  The development of digital processing technology has not only made the delay-line  canceler a more versatile tool for the MTI radar designer, but it has also allowed the applica­ tion or the contiguous filter bank for added flexibility in MTI radar design. 
 Anderson, Y . I. Abramovich, and G. 
 T.: Design of Line-source Antennas for Narrow Ileamwidth ancl [.ow Side l.ohcs, IRE  Trutu., vol. AP-3, pp. 16-28, January, 1955. 
 CONTROLLED VACUUM TUBE IS THAT TRANSIT 
 DIFFERENCE 
 In one approach a single frequency is transmitted and a harmonic of the transmitted  frequency is received. The nature of tile nonlinearity of typical contacts is such that the third  llarmotlic is usually the greatest. The other approach simultaneously transmits two frequencies  1; and f2. 
 Minute variations ill arnplitucie  (AM) and phase (FM) can result in sideband components that fall within the doppler  frequency band. These can generate false targets or mask the desired signals. Therefore both  AM arid FM modulations can result in undesired sidebands. 
 PULSE AMONG MULTIPLE TARGETS 4HE !.-03 
     
 The quartz filter was designed DopplerQuartz From oscillator - Mixerbandpass filterMixer30Me/see 63-70kc/SeC“6496.;;fe;03.5 + coherent L oscillator I t t Navigating Fixed + ;~~~etinL.CIm&pass n%oscillator Mixer 6433.5kc/see123,49~~6.~&%3.5 circuits t 1 Fixed .Shgle.side LGb#MSS oscillator + Mixer -bandfilterToMTI 66.5kc/aec 6500kc/see29,9W:F3.5receiver FIG,16.28.—Block diagram ofaphase-shift unit. byBell Telephone Laboratories. Pending delivery ofthe latter, the circuit was tested bymeans ofLC-filters with one additional mixing step, and found tocancel target motion satisfactorily. 
 IEE, vol. 106, pt. H,  pp. 
 The XAF was tested aboard the battleship New York,  in maneuvers held during January and February of 1939, and met with considerable success.  Ranges of 20 to 24 kiloyards were obtained on battleships and cruisers. By October, 1939,  orders were placed for a manufactured version called the CXAM. 
 2.9 MTI FILTER DESIGN FOR WEATHER RADARS MTI filters are used at the lower elevation angles in weather radars to prevent weather  estimates from being contaminated with ground clutter returns. It is, however, also  very important to preserve an accurate measurement of weather intensity and precipi - tation rate. To meet this dual objective, MTI filters with narrow fixed clutter rejection  notches and flat passbands are needed. 
 The proposed method accommodates aspect dependent scattering better than CS and debiased-CS. The experiment results demonstrate its validity. Author Contributions: Conceptualization, Z.W.; Data Curation, B.Z.; Methodology, Z.W.; Project Administration, B.Z.; Supervision, B.Z. 
 In general,  a power amplifier module, as shown in Figure 11.13, consists of a number of identical  amplifiers that are parallel-combined and isolated from one another through the use  of microwave combining and isolating techniques. Drive power for this parallel group  is obtained from driver or predriver stages, using phase- and amplitude-matched mir - ror-imaged microwave power dividers. A circulator at the module output port is com - monly used to protect the amplifier from the damaging effects of high-load VSWR,  most notably from the antenna. 
 Fung, “A study of the validity of the integral equation model by moment  method simulation—cylindrical case,” Remote Sensing of Envir ., vol. 29, pp. 217–228, 1989. 
 Nar~igation  (Lorldo~r). vol. l I. 
 TO 
 The efficiency of an integrator that operates continuously without dumping is  [l -exp (-ny)]2  p = -----· --------- " tanh (r/2) (2.351,)  The maximum efficiency of a dumped integrator occurs for}'= 0, but for a continuous integra­ tor the maximum efficiency occurs for II}'= 1.257.  2.7 RADAR CROSS SECTION OF TARGETS  The radar cross section of a target is the (fictional) area intercepting that amount of power  which. when scattered equally in all directions, produces an echo at the radar equal to that  from the target; or in other terms,  power reflected toward source/unit solid angle I E 12  <J = incident power density/4n = !~ 4nR2 E:  where R = distance between radar and target  E, = reflected field strength at radar  E; = strength of incident field at target (2.36)  This equation is equivalent to the radar range equation"'of Sec. 
   2!$!2 #2/33 3%#4)/.   £{°Îx FROM THE ANGLE DOMAIN TO THE CROSS 
 F. Dellwig. and B. 
 The primary performance characteristics of A/D  converters are the sample rate or usable bandwidth and resolution, the range over  which the signals can be accurately digitized. The resolution is limited by both noise  and distortion and can be described by a variety of parameters. Sample Rate. 
 DOPPLER  S n FD   PLANE 4HE MAXIMUM VALUE OF THE AMBIGUITY FUNCTION IS UNITY AT THE ORIGIN S    FD       99UD UF      Ta      4HE VOLUME UNDER THE AMBIGUITY SURFACE IS UNITY FOR ANY WAVEFORM UT    
  
 , 
 BEAM AMPLIFIERS SO MULTIPLE STAGES OF AMPLIFICATION ARE REQUIRED   AND ITS NOISE LEVEL IS HIGHER THAN THE LINEAR 
 The position of a false target image in range can be controlled by delaying in time  the read-out samples going to the image synthesizer. The range-doppler image of a ship  with 32 range bins is synthesized as an example in Pace et al.175 ECCM techniques to  defeat this type of jamming signals are similar to those proposed for SAR. Over-the-Horizon Radar. 
 BEAM ROTATION ANGLE  INDICATES THE PORTION OF THE ERROR CAUSED BY EACH TRACKING AXIS 4HE PERFORMANCE OF SCANNING AND LOBING RADAR RELATIVE TO THE BEAM OFFSET ANGLE IS  DESCRIBED IN "ARTON  !N OPTIMUM BEAM OFFSET IS DESCRIBED AS A COMPROMISE BETWEEN  THE LOSS OF ANTENNA GAIN AND THE INCREASE IN SENSITIVITY TO TARGET ANGLE DISPLACEMENT FROM THE ANTENNA AXIS AS BEAM OFFSET IS INCREASED 4HE OPTIMUM OFFSET IS TYPICALLY CHOSEN TO PROVIDE THE MINIMUM RMS ANGLE 
 Digital filtering and decimation is required to produce data rates that can  be handled by conventional processors. This function is either performed as an integral  part of the A/D converter function or can be integrated into the digital downconversion  function used to generate digital I and Q data, as described in Section 6.11. Performance Characteristics. 
 1959.  48. Sterri. 
 10. There it is shown that techniques are available for achieving a resolution significantly finer than that corresponding to the pulse width, provided a signal of sufficient bandwidth is transmitted. Since pulse com- pression is adequately treated in that chapter, the present chapter will discuss pulse compression techniques only for cases in which the pulse compression technique is intimately involved with synthetic aperture techniques. 
 The relative range and bearings of  a target derived from AIS data are entirely independent of the radar measurements  of these parameters. Clearly, any observed differences in radar and AIS positions  will then indicate an error in some process, provided the differences are outside the  expected noise in the measurements. This can be highlighted for the user. 
 After Ref. 36. the known pulse shape to the received data and comparing the residue square error with a threshold.37 If only one target is present, the residue should be only noise and hence should be small. 
 R. Armstrong and M. Axelbank, “Description of the long-range imaging radar,” Project Report  PSI-85, Massachusetts Institute of Technology, Lincoln Laboratory, November 16, 1977. 
 BEAM POINTING "Y REPLACING THE ESTIMATED DISTUR 
 iR0(t)is the unit vector of R0(t)and Vis the spatial domain where the reﬂectivity function zTis deﬁned. Z X Yp݄ 2ݎ   Rt (x0,y0,0)z zz Figure 3. Geometry of the ISAR system. 
 On the synchronizer po\ver supply pin jacks are provided topermit measurement ofpower- supply voltages. Other test points are incorporated onmany ofthe subclasses ofthe transmitter-receiver unit. These external test points permit aroutine procedure ofinspection and preventive maintenance to detect incipient failure and insure peak performance. 
 29-41, 1975.  59. The SCR-584 Radar, Electronics, pt. 
 taneous AGC circuits areprovided and can beswitched inoroutatthe will ofthe operator. The AFC operates from aseparate mixer and amplifier and isofthe hunt-lock type described inSec. 12.7. 
 SIDED SPECTRUM THAT IS SIGNIFICANTLY NARROWER THAN THE SPECTRUM  ABEAM &OR MODERATE PLATFORM SPEEDS AND LOWER 
 Although a wcll-designcd andcngineered receiver willnotlimitthereceived signalundernormalcircum­ stances. intensity modulated CRTdisplays suchasthePPIortheB-scope havelimiteddyna­ micrangeandmaylimit.Somereceivers, however, mightemploy limiting forsomespecial purpose, asforpulsecompression processing forexample. Limiting resultsinalossofonlyafraction ofadecibelforalargenumber ofpulses intcgrated. 
 (Tracking radars are normally operated with range gates.) Tlle boxcar gcncri~tor  corlsists of an electric circuit that clamps the potential of a storage element, sucll as a capacitor,  to the video-pulse amplitude each time the pulse is received. The capacitor maintains the  potential of the pulse during the entire repetition period and is altered only when a new video  pulse appears whose amplitude differs from the previous one. The boxcar generator eliminates  the pulse repetition frequency and reduces its harmonics. 
 Stabilization oftheantenna addstotheweightandsizeoftheradar,butitisnecessary in manyapplications ofradaronshipsandaircraft.Therequirements forstabilization dependin partonthenatureoftheapplication. Requirements differwhether theradarisusedforsurface search,airsearch,tracking, orheightfinding. Therearethreekindsofplatform motionthatcanaffectthelocation oftheantenna beam. 
 WhenanRFamplifier isinsertedaheadofthemixerstage,andifnochangeismadeinthe remainder ofthereceiver, theminimum signalwillbereduced because ofthelowernoise figureoftheRFamplifier, butthemaximum signalthatcanbehandled bythereceiver will alsobereduced byanamount equaltothegainoftheamplifier. SincethegainoftheRF amplifier isusuallyhighcompared tothereduction inreceiver noise-figure, thenetresultisa reduction inreceiverdynamic range.However, thiscanbecorrected andtheoriginaldynamic rangerecovered byreducing thegainoftheIFamplifier tomaintain aconstant output(or constant noiselevelgoingintothedisplay).54 Ontheotherhand,ifthemixerratherthanthe IFamplifier iswhatlimitsthetotaldynamic rangeofthereceiver, theintroduction ofthe low-noise front-end willcauseasacrifice inthemixerdynamic rangeand,consequently, thedynamic rangeoftheentirereceiver.7 Alow-noise receiver mayalsonotbewarranted iftheRFlossespreceding thereceiverare high.FromEq.(9.15)theoverallnoisefigureofaradarreceiver withanoisefigureF,preceded byRFcircuitry withaloss.l...ttF'isequaltoFr.l...ttF'Inaradartheoverallloss.l...ttFduetothe. RECEIVERS, DISPLAYS, AND DUPLEXERS 353  transn~ission line, rotary joint, duplexer, receiver protector, and preselector filter might not be  insignificant. 
 Wavelen@h S’caling.-Since the wavelength ofthe radiation from a magnetron isfixed oratbest variable over alimited range, operation on different wavelengths requires different tubes. Toafirst approximation, magnetrons ofdifferent wavelength are derived from one another bya simple over-all scaling process. Allessential dimensions ofthetube are altered bythe scaling factor a=A/XO, where Aisthe new wavelength desired and XOisthewavelength associated with theoriginal dimensions. 
 DOW AT  '(Z IS ABOUT AS WIDE AS THE ENTIRE MICROWAVE SPECTRUM  !S MENTIONED PREVIOUSLY  FOR RADAR PURPOSES  THE MILLIMETER WAVE REGION  IN PRACTICE  GENERALLY STARTS AT  '(Z OR EVEN AT HIGHER FREQUENCIES 4HE TECHNOLOGY OF MILLIMETER WAVE RADARS AND THE PROPAGATION EFFECTS OF THE ENVIRONMENT ARE NOT ONLY DIFFERENT FROM MICROWAVE RADARS  BUT THEY ARE USUALLY MUCH MORE RESTRICTING 5NLIKE WHAT IS EXPERI 
 Itisdiscussed separately inthenextsection.Oneofthemore popular formsofphaseshiftersisonethatvariesthephysical lengthoflinetoobtainachange inphase,especially whenthelengthsoflinearequantized digitally. Varying thevelocity of propagation byvaryingthepermeability isthebasisofferritephaseshifters.Gasdischarge and ferroelectric phaseshiftersareexamples ofdevicesthatdependonchanges indielectric con­ stanttovarythevelocity ofpropagation, andhencethephase.Thevelocity ofpropagation may~lsobevariedinamoredirectmanner asintheEagle,ordelta-a,scanner wherethe narrow wallofawaveguide ismovedmechanically toproduce achange inphaseanda scanning beam.20 Manyphase-shifting devicesarereciprocal inthatthephasechangedoesnotdependon thedirection ofpropagation. Someimportant phaseshifters, however, arenonreciprocal. 
 D. R. Lyzenga, A. 
 REPORT TIME THIS  CAN BE RELATED TO THE AVERAGE TIME 4!6' BETWEEN FALSE REPORTS BY      4&2 y 4!6' LN    .&-    K&- MAX2MAXC    NUMBER OF INDEPENDENT DOPPLER FILTERS IN THE DOPPLER  CORRELATION WINDOW  K&- MAX   STEEPEST LINEAR 
 The resulting sinusoid isthen passed through aphase shifter controlled byaphase-sensitive Servomechatim asbefore. Although this method issimple, itplaces Modulated oscillator AudD I1: Filter oscillator o-~Videosignals (a) Phase comparator I ,, Bsin(2rrfot+@ ,f,(~: byfo) Scan BsinZrrJOt ,f2(Mm. byf.) 4m-+Toindicators Videosignalsandtriggerpulw (b) FIG. 
 # AMPLIFIERS ARE BIASED SUCH THAT CONDUCTING CURRENT IN THE TRANSISTOR FLOWS FOR  LESS THAN  OF THE  INCIDENT INPUT VOLTAGE SIGNAL 4HIS ALLOWS FOR THE HIGHEST EFFICIENCY AT THE EXPENSE OF POWER GAIN AND WITH THE HIGHEST LEVEL OF NONLINEAR OPERATION #LASS 
 140-146. April1972.(Reprinted inref.18.) 29.Dunn.J.H.•D.D.Howard, andA.M.King:Phenomena ofScintillation NoiseinRadar Tracking Systems. Proc.IRE,vol.47.pp.855-863. 
 ING THE INTERPULSE INTERVAL  THE RESPONSES MAY BE COMBINED TO PRODUCE THE SCATTERING MATRIX OR -UELLER MATRIX "Y COMBINING THE SIGNALS IN PROCESSING  THIS METHOD PERMITS SYNTHESIZING EQUIVALENT TRANSMITTED POLARIZATIONS WITH ANY ELLIPTICITY AND ORIENTATION ! COMMONLY USED WAY TO DESCRIBE THE POLARIZATION CHARACTERISTICS OF A TARGET IS THE  POLARIZATION SIGNATURE   4HIS CONSISTS OF TWO THREE 
 £Ç°ÎÓ  2!$!2 (!.$"//+  7E NOW CONSIDER \C  $E \   THE CHANGE IN $E  DUE TO A CHANGE IN H GIVEN BY \C  H\   \   \ \ \DFP LD $ N, 2H    !NTENNAS  !  AND " MAY BE CONSIDERED AS SEPARATED IN VERTICAL DISTANCE ON AN AIRCRAFT  4HE RELATIONSHIP BETWEEN C  $E  AND A VARIATION IN TERRAIN ALTITUDE C  H IS  \\\   \DLDF PH2 N, $       ANTENNAS SEPARATED VERTICALLY     )N3!2 FOR TERRAIN ELEVATION MEASUREMENT CAN ALSO BE PERFORMED BY AN AIRCRAFT WITH  TWO  ANTENNAS SEPARATED  HORIZONTALLY PERPENDICULAR TO THE FLIGHT PATH  BY  , 4HE AIRCRAFT  IS BANKING AT ANGLE  F     AND COLLECTING DATA FROM THE FLAT GROUND AT GRAZING ANGLE  X  &IGURE   4HEN THE EFFECTIVE APERTURE PERPENDICULAR TO THE ,/3  IS  , SIN X   F     INSTEAD OF ,COS X  &ROM &IGURE   WE HAVE  \\\   \C OS SIN  DLDF Y PY GH2 N,  $       ANTENNAS SEPARATED HORIZONTALLY     )N  EITHER GEOMETRY  SINCE BOTH CHANNELS ARE NOISY  THE EXPECTED ACCURACY IN THE  PHASE DIFFERENCE  
 This ispeak-detected bythe cathode follower Vl, whose cathode circuit has atime constant that islong compared with the period ofoscillation. The cathode and grid ofVIare sobiased that theformer isatground potential intheabsence ofsignal. The demod- ulated voltage controls asawtooth generator ofthe ordinary type, thus providing sawteeth modulated inproportion tothe elevation angle. 
 Thus, the maximum ratio of main-beam clutter to system noise measured  at the receiver output ( C/N), including the fluctuation margin as discussed above, is the  predominant parameter that determines stability requirements. Target returns compete with clutter returns and noise for detection. Suppose desired  targets have sufficient radial speed so that they lie in the clutter-free region of doppler  frequency when a pulse doppler waveform is used. 
 £ 3TRUCTURE AND #HARACTERISTICS  4HE %ARTHS ATMOSPHERE IS A COLLECTION OF MANY  GASES TOGETHER WITH SUSPENDED PARTICLES OF LIQUIDS AND SOLIDS %XCLUDING VARIABLE COMPONENTS SUCH AS WATER VAPOR  OZONE  SULFUR DIOXIDE  AND DUST  THE GASES OF NITROGEN AND OXYGEN OCCUPY ABOUT  OF THE VOLUME  WITH ARGON AND CARBON DIOXIDE BEING THE NEXT TWO MOST ABUNDANT GASES &ROM THE %ARTHS SURFACE TO AN ALTITUDE OF APPROXIMATELY  KILOMETERS  MECHANICAL MIXING OF THE ATMOSPHERE BY HEAT 
 RATIO ANTENNA TYPICAL OF SPACE 
 . Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 108     The number of phase shifts of the reflection changes with trihedral corners dependent on the  incidence angle of the wave, as shown in Figure 11.15.     Figure 11.15  Types of reflections with trihedral corners. 
 VIDED BY THE VEHICLE MANAGEMENT GLOBAL POSITIONING SYSTEM AND INERTIAL NAVIGATION SYS 
 %RROR #OMPONENTS . °{È  2!$!2 (!.$"//+  °£ÓÊ 
 Hansen  (ed.), Academic Press. New York, N.Y., 1966, chap. I. 
 Electronic effi- ciencies depend onthemagnetic field, onr-floading, and onthecathode- to-anode radius ratio. Electronic efficiencies ofabout 70per cent are realized over avery large range offrequencies. Circuit efficiencies depend onthefrequency, since this determines theconducting skin depth which inturn governs thecopper losses. 
 TG 882, March 1967. 50. P. 
 60. G. Linde, “Reduction of radar tracking errors with frequency agility,” IEEE Trans ., vol. 
 In some 3D radars (range, azimuth, and elevation) that display the outputs at all  elevations on a single PPI (range, azimuth) display, the collapsing of the 3D radar information  onto a 2D display results in a loss. A collapsing loss can occur when the output of a high­ resolution radar is displayed on a device whose resolution is coarser than that inherent in the  radar. A collapsing loss also results if the outputs of two (or more) radar receivers are  combined and only one contains signal while the other contains noise. 
 CAL POINTING WIND PROFILING FIXED 
 These calculations must be performed in a  short period of time. The use of the orthogonal phase commands mTxs, nTys helps to  minimize these calculations. Once the element-to-element phase increments Txs, Tys  have been computed for a given beam-pointing direction, the integral multiples of Tys  may be used to steer the columns (Figure 13.8). 
 At lower wind speeds KP depends on SNR as well as on the number of  statistically independent looks. The details of any expression such as this depend on  the underlying statistical model, which is gaussian in this classic expression. However,  the general principle is that the scatterometer must provide many independent looks  to reduce the standard deviation of the s  0 measurement, regardless of the statistical  distribution of the ocean’s backscatter. 
 A DDC avoids these problems,  though it is vulnerable to the phase noise of the ADC sample clock, ADC nonlin - earities, and arithmetic round-off noise. Realizing maximum performance requires  careful attention to design details. Direct Digital Downconversion. 
 BASED RAINFALL  MEASUREMENTS ARE LESS DEPENDENT ON THE UNKNOWN AND VARIABLE DROP 
 One advantage of a storage tube  compared to an acoustic delay line is that it can be used with different pulse repetition  frequencies. That is, a constant prf is not needed. The matching of the delay time and the pulse  repetition period is not critical as in an acoustic line because the timing of the transmitter  pulse starts the sweep of the storage tube. 
 9.2. The auxiliary antennas provide replicas of the jamming signals in the radar antenna sidelobes. To this end the auxiliary patterns approximate the average sidelobe level of the radar receiving pattern. 
 However, when the decoys grow too large, they  have to be engaged if they are thought large enough to carry a weapon. Penetration Aid (Penaids) could be used by incoming ballistic missiles (BMs).23 Penaid  decoys are only one of several possible penaids. A decoy provides another target that the  defense has to handle if the defense cannot distinguish a decoy from a re-entry vehicle. 
 M. Henderson and A. J. 
 11. L. Pryce: The Calculation of Field Strengths over a Spllerical Eartli. 
 37 (12) (13) Inthese equations aistheamplitude reflection coefficient. The boundary conditions that thetangential components ofEand of Hbecontinuous atz=Oimmediately yield (14) Itisclear that awill beOifc=p. 31aterial with such aproperty \vill serve asanabsorber ofthe second kind, providing chas aconsiderable imaginary part. 
 TIES EVER SINCE THE EARLY S L !UTOMATIC DETECTION AND TRACKING FOR SURVEILLANCE RADARS L 3ERIAL PRODUCTION OF ELECTRONICALLY SCANNED PHASED ARRAY RADARS L )NVERSE SYNTHETIC APERTURE RADAR )3!2  THAT PROVIDED AN IMAGE OF A TARGET AS NEEDED  FOR NONCOOPERATIVE TARGET RECOGNITION OF SHIPS L $OPPLER WEATHER RADAR L 3PACE RADARS SUITABLE FOR THE OBSERVATION OF PLANETS SUCH AS 6ENUS L !CCURATE COMPUTER CALCULATION OF THE RADAR CROSS SECTION OF COMPLEX TARGETS L -ULTIFUNCTION AIRBORNE MILITARY RADAR THAT ARE RELATIVELY SMALL AND LIGHTWEIGHT THAT FIT  IN THE NOSE OF A FIGHTER AIRCRAFT AND CAN PERFORM A LARGE NUMBER OF DIFFERENT AIR 
 Sensors 2019 ,19, 516 where ηis the off-nadir angle of the PALSAR. To ensure that the ISR and PALSAR observe the same space, the best choice is to ﬁnd an observation of ISR that just to illuminate the area of PALSAR. However, this kind of observation is not available, so we picked the observation closest to that of PALSAR as a representation and assumed that the ionosphere is stable within the observation area. 
 BISTATIC RADAR  23.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 Research was started in the 1990s to improve the quality of bistatic SAR images,  which were constrained to coherent integration times of a few seconds1 and conse - quently were of limited tactical interest. Specifically, local oscillator phase instabilities  were reduced and bistatic automatic focusing ( autofocus ) algorithms were developed  to improve range measurement accuracy from the antenna phase center to the imaged  scene. Bistatic autofocus requires that the position of both transmit and receive plat - forms must be tracked with subwavelength relative accuracy to correct time-varying  phase errors as part of the image formation process. 
 THAAD is a ground-based sys - tem designed to destroy the theater ballistic missile threats to troops, military assets,  and allied territories. THAAD consists of a hit-to-kill missile, radar, launcher, and  Battle Management/Command, Control, and Communications (BMC3) system. The THAAD radar (see Figure 13.49) is an X-band, phased array, solid-state radar  capable of search, threat detection, classification, and precision tracking at long ranges. 
 F. Pasqualucci, B. W. 
   PP n  3EPTEMBER    " ( #ANTRELL AND ' 6 4RUNK  h#ORRECTIONS TO @ANGULAR ACCURACY OF A SCANNING RADAR EMPLOYING  A TWO 
 I 360 THEMAGNETRON ANDTHEPULSER [SEC. 10.7 Now that apractical and highly efficient discharging circuit hasbeen shown tobefeasible, there remaimthe problem ofreplenkhing theenergy ofthe pulse-forming network. This could bedoneby using aresistance asisolating element. 
 is the constant which depends on the false-alarm probability. Taking the logarithm  gives  (10.36)  This states that for optimum processing one should take the pulses, each of amplitude v1  " (where i = 1, 2, ... , 11), and sum them according to the law L In J0(av1). 
 In addition, the RF gating transients are usually further reduced in amplitude by the IF gating circuit. Transmitter Leakage. The on-off ratio required for the overall transmitter blanking circuits is fairly large (more than can be obtained readily at RF without excessive insertion loss). 
 E. M. Bracalente, W. 
 By reciprocity, an antenna designed to radiate a particular po- larization will also receive the same polarization. The most general polarization is elliptical polarization (EP), which can be thought of as imperfect CP such that the E field traces an ellipse instead of a cir- cle. A clear discussion of polarizations can be found in Kraus.6'7 Another increasingly important consideration for radar antennas is not only what polarization they radiate (and receive) but how pure their polarization is. 
 The gaussian density function has a bell-shaped appearance and  is defined by  where exp [ ] is the exponential function, and the parameters have been adjusted to satisfy the  normalizing condition of Eq. (2.10). It can be shown that  *-m -02  The probability density of the sum of a large number of independently distributed quanti-  ties approaches the gaussian probability-density function no matter what the individual dis-  tributions may be, provided that the contribution of any one quantity is not comparable with  the resultant of all others. 
 TIBLE TO THERMAL RUNAWAY AND DOES NOT REQUIRE THE AMOUNT OF GAIN 
 However, a thin dielectric matching sheet has been used for a 400-element array,51 and some compensation has been achieved without any noticeable slow-wave phenomenon. FIG. 7.21 Planar array with a thin dielectric sheet spaced a fraction of a wavelength from the radiators. 
 L. Walker, H. M. 
 5. Saunders, W. K.: CW and FM Radar, chap. 
 OTHER RADAR TOPICS 559  frequency alone and tl~e radar has no MTI capability. Also. the location of the target position  from ttie measurement of tlle total scattered path length S is indeterminate, as mentiorled  previously. 
 MING THE CONTRIBUTIONS COHERENTLY OR NONCOHERENTLY  AS GOVERNED BY THE OBJECTIVE OF THE CALCULATIONS3CATTERING &EATURE /RIENTATION   !PPROXIMATE 2#3 .OTES #ORNER REFLECTOR !XIS OF SYMMETRY ALONG ,/3 O ! EFF K  &LAT PLATE 3URFACE PERPENDICULAR TO ,/3 O !K  3INGLY CURVED SURFACE 3URFACE PERPENDICULAR TO ,/3 O A,K  $OUBLY CURVED SURFACE 3URFACE PERPENDICULAR TO ,/3 O AA  3TRAIGHT PLATE EDGE ,/3 PERPENDICULAR TO FRONT EDGE     AND % IN PLANE OF PLATE,O   #URVED EDGE %DGE ELEMENT PERPENDICULAR TO ,/3 AK    #ONE TIP !XIAL INCIDENCE K SIN@     !CUTE FLAT METAL CORNER ,/3 PERPENDICULAR TO REAR EDGE AND    % IN PLANE OF PLATEK    !CUTE FLAT METAL CORNER ,/3 ALONG CORNER BISECTOR AND %     IN PLANE OF PLATEK    ./4%3  ,/3   LINE OF SIGHT ! EFF   EFFECTIVE AREA CONTRIBUTING TO MULTIPLE INTERNAL REFLECTIONS  !   ACTUAL AREA OF THE PLATE A   MEAN RADIUS OF CURVATURE ,   LENGTH OF SLANTED SURFACE A   A   PRINCIPAL RADII OF SURFACE CURVATURE IN ORTHOGONAL PLANES  ,   EDGE LENGTH A   RADIUS OF EDGE CONTOUR @   HALF ANGLE OF THE CONE %MPIRICAL VALUES REPORTED BY +NOTT  3HAEFFER  AND 4ULEY 4!",%  2#3 !PPROXIMATIONS FOR 3IMPLE 3CATTERING &EATURES. 
 CRAFT VELOCITY  AND DECREASES WITH INCREASING SPACECRAFT ALTITUDE AND INCIDENT ANGLE !LERT )N CERTAIN 3!2 PROCESSING LITERATURE  THE EFFECTIVE VELOCITY FOR THE ORBITAL CASE IS DENOTED hRADAR VELOCITY v A RATHER MISLEADING AND INAPPROPRIATE TERM 4HE AVERAGE DATA RATE FROM SPACE 
 . #+#*% *($    & (# ** %$%," # $  
 For a typical backward-wave CFA, the power output can vary 100 percent for a 10  percent change in frequency.15 It is possible, however, with conventional modulator  techniques, to operate the backward-wave CFA over a wide band with little change in output  power. The type of modulators normally used with cathode-pulsed CF As can readily compen­ sate for the power variation with frequency of a backward-wave CF A and hold the variation of  output power within acceptable levels. This is a result of the nature of the dispersion character­ istics of such tubes. 
 The airborne radar team under E G Bowen comprised Dr A G Touch, Robert Hanbury-Brown, Bill Eastwood, Perce Hibberd, Sidney Jefferson and Keith Wood. Much of this early work is recorded in memoirs written by team members [ 5–7]. It is also recorded in an of ﬁcial history of ASV radar development, published by the Air Ministry in 1954 [ 1] and a memorandum written by Dr Touch whilst in the USA in 1945 [ 8]. 
 FED SERIES FEED AND B  GABLED PHASE DUE TO FEED &EED #7 "ANDWIDTH   0ULSE "ANDWIDTH   %QUAL LINE LENGTH "EAMWIDTH  ¾ BEAMWIDTH %ND 
 To convert this vector velocity to a horizontal reference on the  grotuid, rile dircctioli of the vcrtical ~ni~st he deterniiried by some auxiliary means. The heading  of tlie aircraft, as rniglit be obtained fro111 a compass, rrlust also be known for proper naviga-  tion. Ttie vertical reference rnay be used either to stabilize the antenna beam system so as to  align ~t with tile iiori7or1tal, or alternatively, the antetitias might be fixed relative to the aircraft  arid the ground velocity components calci~lated with a computer. 
 Each of the four final stages  delivers 110 W peak for 16-ms pulse widths at duty cycles up to 25%. More than  180,000 transistors have been built into more than 25,000 modules. Future upgrades of  this design in the BMEWS arrays will use the more powerful and efficient Si LDMOS  FET technology for enhanced performance capabilities. 
 Bistatic RCS Region. The bistatic angle at which the equivalence theorem fails to predict the bistatic RCS identifies the start of the second, bistatic region. In this region the bistatic RCS diverges from the monostatic RCS. 
 The limiting comp o- nents will be the m edium power amplifier and the antenna elements. Using wideband comp o- nents (antennas, mixers, amplifiers, etc.), a wide variety of spectral transmit modes, e.g. narrow- band, wideband, and multi- carrier, are possible. 
 The output of the mixer is followed by a  low-pass filter which allows only the d-c and the low-frequency modulation components to  pass while rejecting the higher frequencies in the vicinity of the carrier. The coherent detector  provides a translation of the carrier frequency to direct current. It does not extract the  modulation envelope and is a truly linear detector, whereas the" linear" envelope detector was  not linear in the same sense. 
   v  0ROC  )%%%  VOL   PP n  &EBRUARY   % , #OLE ET AL  h!32 
     n   !FTER 2 + -OORE  + ! 3OOFI  AND 3 - 0URDUSKI ¡ )%%%  ./4% P     TO n 6ALUES OF COEFFICIENTS IN THIS TABLE ARE ALSO CONSIDERED THOSE OF THE MODEL4!",%    2EGRESSION 2ESULTS FOR 'ROUND 
 The radar computer receives inputs from the on-board systems, such as the inertial unit and operator controls, and performs as a master controller for the radar. As such, it does the track loop and automatic gain control (AGC) loop filtering, antenna scan pattern generation, and clutter positioning as well as the target- processing functions (such as centroiding). In addition, the computer performs the multiple-target track functions when the radar is in a track-while-scan mode and may execute radar self-test and calibration routines. 
 Since slant range isinvolved inevery radar situa- tion, itinevitably appears inatleast one display onevery set. Itisthe coordinate most frequently duplicated when more than one type of display isused byagiven radar set, partly because displays presenting range have the greatest signal-to-noise discrimination, and partly for geometrical reasons. Range isdisplayed bycausing the electron beam ofthe CRT to move (sweep) across the tube atauniform rate Istarting f1om agiven point orline atadefinite time ineach pulse cycle. 
 Experimental and developmental systems some- times are assigned special indicators enclosed in parentheses, immediately fol- lowing the regular designation, to identify the development organization; for ex- ample, (XB) indicates the Naval Research Laboratory, and (XW) indicates the . Rome Air Development Center. Empty parentheses, commonly called ''bow- legs," are used for a developmental or series "generic" assignment. 
 J. Willis, “Sanctuary radar,” Proc. Mil. 
 Introduction Synthetic Aperture Radar (SAR) imaging is able to work day and night under all weather conditions [ 1]. Therefore, it has wide applications in topographic mapping, environmental monitoring and information acquisition, but the electromagnetic scattering property of a complex object varies with incidence angle [ 2]. In order to meet requirements of omnidirectional observation, it is necessary to implement new research on SAR imaging systems. 
 12.6 DIFFRACTION  In free space, electromagnetic waves travel in straight lines. In the earth's atmosphere, radar  waves can propagate beyond the geometrical horizon by refraction. Another mechanism that  permits radar coverage to be extended beyond the geometrical horizon is djffractio,~. 
 Transmitted  RF signals are “boun ced” off a target  and a  receiver measures the  characteristics  of the echo . Most often ,  low duty cycle pulses  are used.   As the  technology has evolved , the basic concept of radar has  not changed. 
 TYPE TRACKING RADARS  AS DESCRIBED LATER  AND GIVES SOME INFORMATION AS TO THE TYPE OF AIRCRAFT %FFECTS OF !MPLITUDE 3CINTILLATION ON 2ADAR 0ERFORMANCE  !MPLITUDE NOISE  TO  SOME EXTENT  AFFECTS ALL TYPES OF RADARS IN PROBABILITY OF DETECTION AND TRACKING RADAR ACCURACY n /NE EFFECT ON ALL TYPES OF TRACKING RADARS IS THE INTERRELATION BETWEEN THE  LOW 
 Two  EIKs were employed in CloudSat (one prime, one redundant) so as to achieve a 99%  confidence of meeting the two-year life requirement. ch10.indd   11 12/17/07   2:19:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 One end ofthe pile rests against abutton held inplace byradial leaf springs;. SEC. 14.5] VOLTAGE REGULATORAS 567 theothe rendisretaine dbyascre wusuallyreferred toasthepile screw orpile-adjusting screw. 
 Police Radars. This is a straightforward application of the CW homodyne radar technique. Controlled leakage is used to supply the required LO signal to a single crystal mixer. 
 ELEMENT LINEAR ARRAY SCANNED TO n ELEMENT SPACING S   K   . 
 H. R.: Statistical Aspects of Ideal Radar Targets, Proc. IEEE, vol. 
 TER AND HARMONIC FILTER COMBINATION MIGHT HAVE A  TO  -(Z PASSBAND AND A STOPBAND FOR  -(Z AND HIGHER FREQUENCIES A SECOND COMBINATION MIGHT PASS UP TO  -(Z AND REJECT  -(Z AND HIGHER  AND THE DESIGN WOULD CONTINUE IN THIS MANNER TO THE HIGHEST FREQUENCY OF OPERATION 3OME SKYWAVE RADAR DESIGNS CALL FOR UP TO SIX BANDS ! RELATED ISSUE IS THE OCCURRENCE OF MUTUAL COUPLING BETWEEN ANTENNA ELEMENTS IN THE TRANSMIT ARRAY  %NERGY COUPLED BACK INTO AN AMPLIFIER FROM ITS NEIGHBORS CAN REACH  LEVELS THAT RESULT IN INTERMODULATION DISTORTION  AS WELL AS CAUSING LOAD RESONANCES THAT STRESS THE AMPLIFIER CHAIN !NTENNAS 4HE CHOICE OF ANTENNA CONFIGURATION IS INTIMATELY LINKED TO THE RADAR  MISSION  GENERALLY DEFINED IN TERMS OF TARGET TYPES  RADAR COVERAGE  AND COVERAGE RATE 4HE .AVAL 2ESEARCH ,ABORATORY MAGNETIC 
 154 INTRODUCTION TO RADAR SYSTEMS  C\J  C: C:  0 0  :E :E  "' "' 0 0 a.. a..  (al  t  Q.)  "CJ ::::, ...... 
 Info. Proc. Sys. 
 BIT MAXIMAL LENGTH SEQUENCES #+!- ) (, %/   
 L. S. Gunn: Scattering of Microwaves by a Melt- ing Spherical Ice Particle, /. 
 PRODUCT  §SEC PULSE 4HE RADAR HAS SUFFICIENT SENSITIVITY TO RESPOND TO RAIN RATES AS SMALL AS  MMHR )NSTRUMENT MASS IS  KG REQUIRED INPUT POWER IS  7 4HE IONOSPHERIC SOUNDING MODE ON -!23)3 DESCRIBED ABOVE  IS AIMED PRIMAR 
 In practice, peak sidelobe levels as low as -30 to -35 dB (average level, -5 to -20 dB) can be readily realized with phased array antennas which electronically scan. To obtain sidelobes at lev- els -45 dB down from the main beam (average level, below —20 dB), the total phase-error budget is required to be in the order of 5° rms or less. This is ex- tremely difficult in arrays which electronically scan: the errors induced by phase shifters, active components, and feed elements must be included in this budget. 
 vol. 56.  pp. 
 MODULATION )-$   CROSS 
 Airborne scanners ofthis type are usually mounted ontheunder side ofthefuselage, theantenna being below the pedestal. Sector scanners arecinematically similar tocircular scanners. Toenable the radar operator tocontrol theantenna from adistance the tilting isusually actuated byamotor. 
 26. B. L. 
 10,000 Mc/sec (FM)...100watts average 100watts average 250watts peakvideo level 500 watts peak inpulses 30wattsaverage 30wattsaverage 80wattspeakvideo level 175 watts peak inpulses 25wattsaverage {25wattsaverage 40wattspeakvideo level 80watts peak inpulses 10watts average 0.1watts average Any ofthese issufficient foruseinapplications where both antennas can bedirective., and there islittle question that the very highest fre-. SEC.17.11] GENERAL EQUIPMENT CONSIDERATIONS 717 quencies will beused forsuch purposes inthe future. Until recently it was not economical touse a-fmodulation ofmicrowaves because ofthe extreme oscillator-stability requirements necessary toavoid excessive bandwidth. 
 Electrical  drives arc Ilic Wan! Leonard type or thyristor bridges driving de motors. Hydraulic drives arc  tiftcn chearcr than electric drives and in the larger sizes (above 50 hp) they are more compact  and often lighter. It has hcc11 said that hydraulics arc less trouble to maintain. 
 In fact, for grazing angles less than a few degrees and moderate to strong wind speeds, several ob- servers have reported that at X band and at the higher sea states the horizontally polarized returns often exceed the vertically polarized returns.1'25'26 The NRL 4FR system permitted transmission and reception on orthogonal po- larizations so that data could be collected for cross-polarized sea clutter. These returns tended to have a weak dependence on grazing angle and were always smaller than either of the like-polarized returns, lying in the cross-hatched region shown on Fig. 13.4. 
 sensors Article Ship Classiﬁcation in High-Resolution SAR Images via T ransfer Learning with Small T raining Dataset Changchong Lu and Weihai Li * Department of Electronic Engineering and Information Science, University of Science and Technology of China, Hefei 230027, China; ll964183@mail.ustc.edu.cn *Correspondence: whli@ustc.edu.cn Received: 19 November 2018; Accepted: 20 December 2018; Published: 24 December 2018/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: Synthetic aperture radar (SAR) as an all-weather method of the remote sensing, now it has been an important tool in oceanographic observations, object tracking, etc. Due to advances in neural networks (NN), researchers started to study SAR ship classiﬁcation problems with deep learning (DL) in recent years. However, the limited labeled SAR ship data become a bottleneck to train a neural network. 
 This group of PE’s, colloquially known as  ‘clutter,’ really determines for us the minimum range  at which we can use any one type of radar gear, because  it is quite unreliable to try to read echoes through the  mass of clutter.  Another familiar radar term is ‘strobe,’ a partly manu-  factured word which accurately describes a very useful  brightening device on the CRT. So far we have talked  of moving the electron beam across the tube, producing  the straight trace of light, and of deflecting it for Cal  pips and signal echoes. 
 The theory and design of paraboloidal reflec - tor antennas are extensively discussed in the literature.13–17 A basic geometry is shown  in Figure 12.16 a, which assumes a parabolic reflector surface of focal length f with   a feed at the focal point. It can be shown from geometrical optics considerations that   a spherical wave emerging from the focal point, F, and incident on the reflector is  transformed, after reflection, into a plane wave traveling in the positive z direction  (Figure 12.16 b). Although reflectors are commonly illustrated with a round outline or rim and a cen - tral feed point, a variety of reflector aperture shapes are used in practice, as shown in  Figure 12.17. 
 (ILL "OOK #OMPANY   . * 7ILLIS  h"ISTATIC RADAR v #HAPTER   IN  2ADAR (ANDBOOK  - ) 3KOLNIK ED   ND %D    .EW 9ORK -C'RAW 
 LOOK DIRECTIONS WERE COLOCATED INTO  
 ATE BOTH INTERACT TO UPDATE  WITH CURRENT MEASUREMENTS  THE TARGETS STATE VECTOR  AND  MAKE THE PREDICTIONS NECESSARY TO POINT THE RADAR BEAM AT THE TARGET THE NEXT TIME IT IS OBSERVED  SELECT THE TYPE OF WAVEFORM TO RADIATE  AND SELECT THE THRESHOLD TO APPLY FOR TARGET DETECTION ! CONCEPTUAL SCHEME SHOWING THE INTERACTION OF SCHEDULING AND TRACKING IS SHOWN IN &IGURE   WHERE  R K  BK  EK ARE THE RANGE  BEARING  AND ELEVA 
 For near-grazing conditions, the models must account for shadowing. Simplified Models.  Early radar theories for ground return assumed, as in optics,  that many targets could be described by a Lambert-law variation of intensity; that is,  the differential scattering coefficient varies as cos2q, with q  being the angle of inci - dence. 
 TENANCE REPLACEABLE ASSEMBLY IS IDENTIFIED WITH HIGH PROBABILITY 3UCH ASSEMBLIES ARE THEN SENT TO A DEPOT FOR REPLACEMENT  REPAIR  FAILURE TRACKING  ANDOR RECLAMATION &OR ASSEMBLIES THAT HAVE A VERY LOW FAILURE RATE  IT IS USUALLY CHEAPER TO REPLACE AND RECLAIM RATHER THAN REPAIR EVEN WHEN THE ASSEMBLY IS VERY EXPENSIVE , 
 WAVELENGTH   RESONANCE %XCEPT POSSIBLY FOR THE DETAILS OF THE ANGLE FACTOR  &P  %Q  IS EQUIVA 
 One distinguishes the wave by the position of the ele ctrical field  components based upon the direction of propagation and spreading. Should  € E and  € S stretch in a  vertical plane, this is vertical polarization.  Should they stretch in a hor izontal plane, this is hor i- zontal polarization. 
 The mixer model and the spurious-effects chart predict the spectral characteristics of a single-ended mixer. In the balanced-mixer con- figuration these characteristics are modified by symmetry. The two most com- mon forms of balanced-mixer configuration are shown by Fig. 
 Although a conical scan radar can also be  operated with only four pulses per revolution, it is more usual to have ten or more per  revolution. This allows the modulation due to the angle error to be more that of a continuous  sine wave. Thus tile prf is usually at least an order of magnitude greater than the conical-scan  frequency. 
 multifunc­ tion radar might not be as efficient as separate ra<lars operating at separate frequencies. each  ortimizcd to fulfill a single, dedicated function. It is conceivable in some circumstances that  two radars, one optimized for surveillam:e and the other for track, will perform belier, be less  costly. 
 Most of the gain and gain  RANGE  TRACKER -- -  t  f  r 7  I: IF PHASE- AZIMUTH ; +- MIXER -C SENSIIIVE AMPLIFIER -  DIFFERENCE DETECTOR  A JUNCTION CHANNEL - - AMPLIFIER Y,,,  ELEVATION -  ANGLE  ERROR  AZIMUTH-  ANGLE  ERROR L  RANGE  Figure 5.9 Block diagram of two-coordinate (azimuth and elevation) amplitude-comparison monopulsc  tracking radar.  162INTRODUCTION TORADAR SYSTEMS intheIFportion ofthereceiver were A~cosWIFe,thedifference signalwouldbeeither AdcoswIFeor-AdcoswIFe(A~>0,Ad>0),depending onwhichsideofcenteristhetarget. Since-AdcosWjFt=AdcosWjF(t+n),thesignofthedifference signalmaybemeasured by determining whether thedifference signalisinphasewiththesumor1800outofphase. 
 UTABLE TO THE NATURAL ENVIRONMENT 4HESE EFFECTS ARE ENERGY ABSORPTION FROM GASSES AND LIQUID WATER  DIFFRACTION  REFRACTION  MULTIPATH INTERFERENCE  EARTH 
 WINDOW DETECTOR FOR THE NO 
 WAVE #7  OR LONG 
 ThePropagation ofMicrowaves. —Further limitations ontheperform- ance ofradar arise from thepropagation properties ofradio waves inthe microwave region ofthe electromagnetic spectrum. Like light, micro- waves arepropagated instraight lines. 
 A total chirp bandwidth of 1.37 MHz is used to obtain a compressed pulse- width of 1µs after weighting and rise - and fall -times of 1  µs are a ssumed. Figure 12.18 shows  the pulse compressed output for a matched filter r eceiver alone (gray curve) and with the addi- tional Gaussian weighting filter added to the matched filter. At the frequency limits of the lin-ear chirp (0.685  MHz) the required r esponse of the Gaussian filter is –26 dB down. 
 25.4 with area c-rRR№K (Ac)r = —— (25.16) 2 cos2 (p/2) where T is the radar's compressed pulse width. The isorange contours are as- sumed to be straight lines within the bistatic footprint. For this example theRANGE-LIMITED CELL(Ac)r ISORANGE CONTOURS TRANSMIT BEAM RECEIVEBEAMARB«cT/2cos(0/2)BEAM-LIMITED CELL (Ac)b (OR BISTATIC FOOTPRINT) . 
 135. M. I. 
 104, pp. 3845–3862, February 25, 1999. 107. 
 Itwasfoundthat65percentoftheclutterexceeded O.tm2,18percentexceeded 1m2,andless than1percentexceeded 10m2•Theclutterwithradarcrosssections greaterthan10m2was limitedto6 minlengthandwasfoundtobeassociated withman-made objectssuchas electricity pylonsandbuildings. Theseparations between clutterlargerthan10m2wasbe­ tween135and675m.Forclutterwhichwasgreaterthan0.1m2,thepatchsizesvariedfrom 2 mtowellover300minlength.Themajority oftheseclutter-patch separations wereJess than30mbutafewexceeded 110m.Forthisterrain,itwasconcluded thatjfaminimum clutterpatchseparation of75m(0.5j.Js)werenecessary fortargettracking, a10m2target couldbetracked99percentofthetime,buta 1m2targetcouldbetrackedonlySSpercentof thetime. Intheaboveexample ofC-banddata,theeGhoesfromman-made objectswere"point" targetsofradarcrosssections greaterthan10m2.Atthelowermicrowave frequencies, the echoesfromthestrongpoint-scatterers canbeseveralordersofmagnitude greater.Theyare oftensolargethattheymightnotbecompletely removed byMTI.Thusitisnotuncommon forMTIradartohaveatitsoutputmanyfixedpoint-scatterers thatmustberecognized soas nottobeconfused withdesiredtargets. 
 Within the European Union (EU), there are two main considerations govern - ing the use of GPR. These are the use first of the equipment as a deliberate radio  frequency radiator and second as an equipment that must satisfy the EMC require - ments of the EU. The European Telecommunications Standards Institute (ETSI)  regulatory body is in the process of drafting specifications and information can be  found at http://www.etsi.org that will cover the use of such equipment as a deliber - ate radio frequency radiator. 
 The threshold settings are a tradeoff between false alarms due to  sidelobe returns and detectability loss in the main channel. An example is shown  in Figure 4.11 for a nonfluctuating target, where the ordinate is the probability   of detection in the final output of the sidelobe blanker and the abscissa is the   signal-to-noise ratio (SNR) in the main channel. The quantity B2 is the ratio of   the guard channel SNR to the main channel SNR and is illustrated in Figure 4.12. 
 The relative importance of these two effects determines whether there is a net increase or  a net decrease in transmission. In unfavorable cases, even strongly relkcting meshes can lose  their reflecting properties almost completely.  Cassegrain antenna.19-23 This is an adaptation to the microwave region of an optical technique  invented in the seventeenth century by William Cassegrain, a contemporary of Isaac Newton. 
 A tubular feeder type 88 was also included, whichallowed the VSWR to be adjusted for the nominal centre frequency of an individual magnetron. The scan speed of scanner type 67 was variable, using control unit type 477 (a 12 ohm variable resistor), over the range 40 –70 rpm, with a normal scanning speed of 60 rpm. The scanner type 51 could scan at up to 90 rpm, which was considered too high. 
 T/R SWITCHING. (1) For switching applications, the FET design should be cho- sen such that the ratio of OFF-ON resistance of the FET is kept as high as possible. The channel length largely determines the ON resistance and hence the insertion loss of the device. 
 3.Portable beacons. Portable beacons used with portable inter- rogators form thebasis ofanew and accurate system ofsurveying. 1Gontrolbw ControlboxI FIG. 
 A. Moreira, G. Krieger, D. 
 The lens array allows more freedom than the reflectarray in designing the feed assembly  since there is no aperture blocking, but the back surface of the reflectarray makes it easier to  provide the phase shifter control and drive assemblies, structural members, and heat removal.  Space-fed arrays are gerlerally cheaper than conventional arrays because of the omission of  the transmission-line feed networks and the use of a single transmitter and receiver rather than  a distributed transnlitter and receiver at each element. A space-fed array may be simpler that;  an array with a constrained feed, but a sacrifice is made in the control of the aperture  il1urnination"and in the maximum power capability of the array. 
 The pulse amplitudes in each beam position are envelope-detected and stored for use in a comparison with those from the other beams. The simplest form of radar sequential lobing compares the envelope-detected returns from a single pulse in each of two adjacent beams. The ratio of the detected pulse amplitude in one beam position to that in the other forms the basis for a table lookup or readout of target elevation angle. 
 OUTPUT CURVE FOR A RECEIVER 4WO EQUAL INCREMENTS IN INPUT SIGNAL $ I   AS SHOWN  PRODUCE DIF 
     8 
 the beam is steerable. The generation of multiple fixed beams or a number of  independent steerable beams requires a duplication of the sampling pulse generators and  sampling mixers.  Other beam-forming methods. 
 The processing times needed to obtain the SLC/PRI images reported in the table are comparable to the standard processing times of other algorithms. 4. Conclusions In this work the SVD decomposition has been used to extract correlated information from SAR raw data on scenes where a strong point scatterer is present. 
 Earlyinthedevelopment ofradar,alettercodesuchasS,X,L,etc.,wasemployed to designate radarfrequency bands.Although itsoriginalpurpose wastoguardmilitarysecrecy, thedesignations weremaintained, probably outofhabitaswellastheneedforsomeconven­ ientshortnomenclature. Thisusagehascontinued andisnowanaccepted practice ofradar engineers. Table1.1liststheradar-frequency letter-band nomenclature adopted bythe IEEE.15Thesearerelatedtothespecificbandsassigned bytheInternational Telecommunica­ tionsUnionforradar.Forexample, although thenominal frequency rangeforLbandis1000 to2000MHz,anL-bandradaristhoughtofasbeingconfined withintheregionfrom1215to 1400MHzsincethatistheextentoftheassigned band.Letter-band nomenclature isnota fOkm IkmWavelength 100m 10m 1m !Oem 1cm lmm OIMm r red---I LF--------+---MF--HF- -VHF- fo-UHF-I-SHF- .....EHF- --VlF Verylow Low Medium High VeryhighUltrohigh Super Extremely frequency frequency frequency frequency frequency frequency high hiqh Ifrequency frequency Myriometric Kilometric Hecrometric Decometric Metric Decimetric Centimetric Millimetric Decimilli- woves woves woves woves woves woves woves woves metricwoves Bond4Bond5Bond6Bond7Bond8Bond9Bond10BondIIBond12 ::i~~~OiA !~e9~~ry~i~s~Submillimeler Fo ~roodcost OTHI JIinfra>------l••bond rodorI Letterdesignotions LSCXKuKa. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 and G(f , k) is the normalized angular spreading function that describes how the wave  energy is distributed in azimuth,  G kd ( ,)f f 021π∫=  The non-zero wave spectrum is not confined to directions having a component par - allel to the wind direction f = 0, i.e., G(f , k) for π π 23 2≤ ≤f , nor is it semi-isotropic,  G k( ,)f =1 π for −≤ ≤π π 2 2f . In general, the angular spectrum is non-zero through 360 °,  with the spreading function depending on many variables, including the recent surface  wind history. 
 The presence  of liiorc than one possible mode of operation means that the magnetron can oscillate in any  o~lc of tlicsd frequencies and can do so in an unpredictable manner. This is the essence of the  stability problem. Tlie mag~ietron must be designed with but one mode dominant. 
 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16   blind folio 16.64 ch16.indd   64 12/19/07   4:56:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 In (c)  Input to A Input for  qenerate matched  transm~l f~ller  waveform  width r Y  Figure 11.19 (a) Example of a phase-coded pulse with 13 equal subdivisions of either 0°(+) or 180°(-)  phase. This is known as a Barker code of length 13. (b) Autocorrelation function of (a), which is an  approximation to the output of the matched filter. 
 PULSE COMPRESSION RADAR  8.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 Time-Frequency-Coded Waveforms.  A time-frequency-coded waveform  (Figure 8.24) consists of a train of N pulses with each pulse at a different frequency.38  Generally, the frequencies are equally spaced, and the pulses are of the same ampli - tude. The ambiguity function for a periodic waveform of this type consists of a central  spike plus multiple spikes or ridges displaced in time and frequency. 
 60 INTRODUCTION TO RADAR SYSTEMS  18  16  14  !g 12  ::; 10 0  g' 8 .  iii C. E 6 -·  0 u 4 -- 2  2 n=I  n=B  n=64  4 6 10 20 40 60 100 200  Collapsing rolio "' l m + n) In Linear  detector  Figure 2.29 Collapsing loss versus collapsing ratio {m + ri)/n, for a false alarm prohahilily of JO O and a  detection probability of 0.5. 
 The plate ofVS.controls the potential ofthe CRT cathode through d-c restorer V7.and itsparallel resistor insuch away that the cathode-ray tube isturned ononly when Vtiisconducting. The range sweep and associated delay circuits areshown inthebottom row. The simple delay multivibrator isnot intended foruse inrange determinations, but can bereplaced bysome such arrangement asthat ofFig. 
 Thl.;Stherequirements foraccuracy andambiguity maynotalwaysbepossible tosatisfysimultaneously. r=signalduration 8=signalbandwidthFigure11.8Anapproximation totheidealambiguity diagram, takingaccounttherestrictions imposed bythe requirement forafixedvalueof(2E)2attheoriginand aconstant volumeenclosed bytheI'lI2surface.. The ambiguity diagram in three dimensions may be likened to a box of sand. 
 K.: CW and FM Radar, chap. 16 of " Radar Handbook," M. I. 
 Semiconductor materials from which transistors are fabricated for  use in solid-state radar transmitters have generally been either silicon or one of the  so-called compound semiconductors, such as gallium arsenide (GaAs), indium phos - phide (InP), silicon carbide (SiC), gallium nitride (GaN), or silicon germanium (SiGe).  Semiconductors like silicon or gallium arsenide have found early wide acceptance  because it has proven practical to control their crystal lattice defects accurately and  repeatably during transistor manufacturing. Some semiconductors, such as gallium  nitride (GaN) or silicon carbide (SiC), are referred to as wide bandgap semiconduc - tors. 
 Please scroll down to see the full text. Download details: IP Address: 128.244.11.5 This content was downloaded on 19/07/2023 at 19:13 Please note that terms and conditions apply. You may also like: Global Approaches to Environmental Management on Military Training Ranges Sustainable Urban Development An historical account of the two-fluid theory for superfluidity J J Hernández-Gómez and R W Gómez-González Towards a catalogue of Sardinian WWII Heritage. 
 Of course, the radar equation is a simplification in assessing ECM-ECCM interac - tions; a measure of ECCM effectiveness should involve the whole weapon system in  which the radar operates. The measure of effectiveness should be expressed in terms  of the number of attackers destroyed or the probability of radar survival. References  in the literature attempt to assess the ECCM efficacy.190–194  Simulation is another means to assess the ECCM benefits in radar and weapon  systems.193 An advantage of this approach resides in the capability to artificially  generate different types of threats and to look at the radar160,161 and weapon system  reactions. 
 8.13 is converted to circular polarization hy a nonreciprocal circular  polarizer (a ferrite quarter-wave plate). In the Faraday rotator portion, the applied longitu­ dinal magnetic field rotates the circular polarization, imparting the desired phase shift. The  circular polarization is converted to linear by a second nonreciprocal polarizer. 
 Guaragnella, C.; D’Orazio, T. A Data-Driven Approach to SAR Data-Focusing. Sensors 2019 ,19, 1649. 
 Itiscapable ofusing and displaying many millions ofseparate data persecond. The geometrical expression which theCRT gives toelectrical phenomena ispeculiarly appropriate toradar, because ageometrical situation involving the various radar targets isprecisely what must usually berepresented. Ofthe other devices mentioned as possible indicators, only the pen-and-ink recorder iscapable ofgiving such ageometrical interpretation, and itisslow and cumbersome by comparison. 
 The parameter ka = 2WX is the circumference of the sphere expressed in wavelengths, and the RCS is shown normalized with respect to the projected area of the sphere. The RCS rises quickly from a value of zero to a peak near ka = I and then executes a series of decaying undulations as the sphere becomes elec- trically larger. The undulations are due to two distinct contributions to the echo, one a specular reflection from the front of the sphere and the other a creeping wave that skirts the shadowed side. 
 This inductance isnotneeded forstabilit ybutdoes improve thenoise figure about 0.25 db. Noise figures obtainable with the double-triode circuit depend on several factors; representative values areshown inTable 12.1. Improve- ments of2dbormore over thepentode circuit areusual. 
 1977.  Arlington, VA, IEEE Publication 77 CH 1255--9 EASCON; see also Microwave System News, vol. 7,  pp. 
 J-ERS-1 operated for eight years, considerably longer  than its two-year design life. RADARSAT-1  Shown in Figure 18.2, RADARSAT-1 marked a major milestone  in space-based SAR. It was the first system to offer the user a choice of resolutions,  incident angles, and swath widths.17 The evolution of these characteristics merits a  brief review. 
 Alldata refer toatemperature of25°C and sea-level pressure. TARLE 14,5.—SPEED CONTROL OFCERT.AIN MOI-OR-ALTERNATOII SETS Ratingh’manufacturervaphase: Eclipse ..............1003+ Eclipse .............2503+ Leland. ...............50010 Wincharger 7501+ Holtzer-C’abet, 1000 3+ Leland ...............1500 1+ GE .... 
 November, 1960.  RADAR ANTENNAS 275 5\Kock.W.E.:Path-length Microwave Lenses.Proc.IRE,vol.37,pp.852-855, August, 1949. 52.RUle,J.:Wide-angle Metal-plate Optics,Pmc.IRE,vol.38,pp.53-59,January, J950. 
 IEEE,  vol. 53, pp. 1257-1258, September, 1965. 
 England). 110. 40. 
 J.: Physical Limitations on Antennas.MIT Research Lah. Electronics Tech. Rept. 
 The attenuation produced hy ice particles in the atmosphcn:, whether occurring as hail.  snow. or ice-crystal clouds, is much less than that caused by raill of an equivalent rate or  precipitation.78 Gunn and East-i1 state that the attenuation in ,;now is  I\ . 
     WHERE S  IS THE SEPARATION IN TIME OF TWO CONSECUTIVE CLUTTER RETURNS&)'52%   -4) IMPROVEMENT FACTOR AS A FUNCTION OF THE RMS VELOCITY SPREAD OF CLUTTER FOR   A FOUR 
 The 360◦whole aperture is divided into 36 subapertures. The pixel size of the SAR image is 0.25 cm ×0.38 cm. We reconstruct the subaperture images with BP , CS, debiased-CS and LS-CS-Residual. 
 STATE ELECTRONICS HAS ACTUALLY BEEN VERY GRADUAL BECAUSE THE POWER OUTPUT OF INDIVIDUAL SOLID 
 105. Bachman, C. G.: "Laser Radar Systems and Techniques," Artech House, Inc., Dedham, Ma, 1979. 
 Free. W.R .. F. 
 11. Peake. and R. 
 SPECIFIC LOSS IS THE DETECTABILITY LOSS IN THE MAIN  CHANNEL CAUSED BY SPURIOUS BLANKING FROM THE GUARD CHANNEL 3EE &IGURE   0ROBABILITY OF &ALSE !LARM  2ADAR DETECTION PERFORMANCE IS DETERMINED BY  THE DETECTION THRESHOLD  WHICH IN TURN IS SET TO PROVIDE A SPECIFIED PROBABILITY OF FALSE ALARM n !S DESCRIBED IN 3ECTION   PULSE DOPPLER RADARS OFTEN EMPLOY  A MULTILOOK DETECTION CRITERION TO RESOLVE RANGE AMBIGUITIES 4HIS CAN BE ACCOM 
 &UNCTION 2ADAR -&2  IS THE 53 .AVYS FIRST SHIP 
 Wang, Y.; Yang, M.; Chong, J. Simulation and Analysis of SAR Images of Oceanic Shear-Wave-Generated Eddies. Sensors 2019 ,19, 1529. 
 These parameters result in  15 liits from a point target on each scan. The process of summing all the radar echo pulses for  the purpose of improving detection is called integration. Ma~y techniques might be employed  for accornplisliing integration, as discussed in Secs. 
 At Low Grazing Angles. At low grazing angles, below mean sea slope an- gles of about 10°, sea clutter takes on a different character. The sharp clutter peaks known as sea spikes began to appear on A-scope presentations,1'25'33 and the probability distributions assume a different form.34 Figure 13.11 shows the presence of sea spikes in the time histories of returns from a fixed spot, measured from a tower in the Gulf of Mexico with a high-resolution X- band radar looking into an active sea at a 1.5° grazing angle.33 The vertically polarized returns appear to be a bit broader, and while the horizontally polar- ized returns are more spiky, both polarizations display the sharp bursts char- acteristic of sea clutter at small grazing angles. 
 RECEIVERS, IJISPLA YS,ANIJIJUPLEXERS 345 Thedefinition ofnoisefigureassumes theinputandoutput ofthenetwork arematched. Insomedevices. lessnoiseisobtained undermismatched, ratherthanmatched, conditions. 
 494 THERECEIVING SYSTEM—INDICATORS [SEC. 136 theplate load isreacthe, thecathode impedance should bealso, with the same sort offrequency response. For pure resistances the feedback ratio isRk/(RL) and GoisRL/(Rk +R~)multiplied bythe gain that would obtain ifboth resistances were intheplate circuit. 
 As a  consequence, the bistatic radar must either employ a greatly elevated ( ∼1 km) trans - mitter at these long baselines or operate with shorter baselines to achieve acceptable  low altitude surveillance coverage. Note that the two-oval case can also require a very  high altitude for the site located in the oval not under surveillance—so high that the  site must often become airborne. Finally, the transmit antenna will be in direct LOS of the receive antenna when L ≤  rT + rR with ht = 0, so that, again with all units in kilometers  L ≤ 130 ( √hT + √hR) (23.8)Case L Area (of one oval) RR(max) (on Rx oval) RR(min)  (on Rx oval) Circle (Benchmark) 0p RM2RM RM One Oval <2RM~p [RM2 − L4/ (64 RM2)](RM2 + L2/4)½ + L/2(RM2 + L2/4) ½ − L /2 Two Ovals >2RM >3RM~p RM2 [RM2/L2] ~p RM2 [RM2/L2] L/2 − (L2/4 − RM2)½ ~RM2/ L(RM2 + L2/4)½ − L /2 ~RM2/ LTABLE 23.1  Area and Detection Ranges for General Ovals of Cassini2 (Courtesy SciTech, Inc. 
 Transfer learning and ﬁne-tune can successfully train a deep model with small datasets. In this paper, we used some pre-trained models for transfer learning, such as Resnet-50, Vgg-16, etc. Depending on structure of different models, we also do some ﬁne-tuning in their layers. 
 101. G. H. 
 A. Oliner and G. H. 
 USE WEATHER AND AIRCRAFT  SURVEILLANCE RADAR BASED ON ELECTRONIC SCANNING AND PULSE COMPRESSION TECHNIQUES   .   -%4%/2/,/')#!, 2!$!2   £°ÎÇ AND AN EFFORT BEGINNING A DECADE LATER CONTINUED THE DEVELOPMENT OF PHASED ARRAY  RADARS FOR CIVIL APPLICATIONS 2ADARS INITIALLY DESIGNED FOR MILITARY APPLICATIONS  WERE MODIFIED FOR WEATHER DETECTION AND SUCCESSFULLY DEMONSTRATED THE CONCEPT )N  THE EARLY S  A JOINT EFFORT BETWEEN THE 53 .AVY  THE .ATIONAL 7EATHER 3ERVICE  THE .ATIONAL 3EVERE 3TORMS ,ABORATORY  AND THE 5NIVERSITY OF /KLAHOMA LED TO THE DEVELOPMENT OF THE SO 
 The performance attainable from the space-time array is limited by the aircraft speed, the array alignment with respect to the aircraft ground track, and the system accuracies. A performance analysis for a 16-element, two-pulse space-time array is pre- sented in Figs. 16.26 and 16.27. 
 INSULATOR 
 The main-beam intensity, being coherent, increases  as the square of the number of elements, whereas the sidelobes due to errors, being incoherent.  increases only directly with the number of elements. The gain of a broadside array of isotropic  elements is approximately  Go= (8.26)  m n  (Note that when imn = constant, G0 = MN.) Then the normalized pattern of Eq. 
 Sparking: Especially when a magnetron is first started, it is normal for anode-to-cathode arcing to occur on a small percentage of the pulses. Sometimes this also applies to moding and/or misfiring. The modulator must tolerate this for brief periods without tripping off and must deliver normal output immediately fol- lowing sparking. 
 STAGE #LASS 
 J. M. Headrick, “HF over-the-horizon radar,” Chapter 24 in Radar Handbook , M. 
 Attacks using radar had a tendency to be more successful than those made by visual sightings, due to the element of surprise. Analysis of night attacks between August 1941 andSeptember 1942 showed that out of a total of 31 attacks only two had been made without the use of ASV and these occurred during bright moonlight. Night attack against U-boats was practically impossible without ASV. 
 SMOOTHED TRACK WIDE  SERVO BANDWIDTH   THE RADAR CAN BREAK LOCK AND LOSE TRACK OF THE TARGET 7HEN THE SURFACE IS ROUGH  CORRESPONDING TO A REFLECTION COEFFICIENT OF ABOUT    THE CHARACTERISTIC OF THE ERROR VERSUS ELEVATION CHANGES IS OBSERVED IN &IGURE  4HE ROUGH SURFACE CAUSES SIGNIFICANT DIFFUSE SCATTERING RATHER THAN A MIRROR REFLECTION 4HIS CHANGES THE SHAPE OF THE ERROR CURVE AND RESULTS IN SOME RESIDUAL ELEVATION 
 It is  possible, however, to obtain more precise criteria for specifying the maximum errors which  may be tolerated in the aperture illumination.  Systematic errors. The effe~t of systematic errors on the radiation pattern may he found by  properly modifying the aperture distribution to take account of the known errors. 
 2. RCA Government and Commercial Systems, Aerospace Systems Division, Burlington, Mass.: "The Apollo LM Rendezvous Radar and Transponder," Kept. LTM 3300-14D, February 1971. 
 If,inanyoftheabovetechniques, movingtargetsaretobedistinguished fromstationary objects,thezero-doppler-frequency component mustberemoved. Thezero-doppler-frequency component has,inpractice, afinitebandwidth duetothefinitetimeontarget,clutterfluctua­ tions,andequipment instabilities. Theclutter-rejection bandofthedoppler filtermustbewide enoughtoaccommodate thisspread.Inthemultiple-filter bank,removal ofthosefiltersinthe vicinityoftheRForIFcarrierremoves thestationary-target signals. 
 GLACIAL AQUIFERS IN THE .ORTH  0OLAR LAYERED DEPOSITS WITH -ARS %XPRESS-!23)3 v  'EOPHYSICAL 2ESEARCH ,ETTERS  VOL     PP ,  *UNE     - +ATO  9 4AKIZAWA  3 3ASAKI  AND THE 3%,%.% 0ROJECT 4EAM  h3%,%.%  THE *APANESE LUNAR  ORBITING SATELLITE MISSION PRESENT STATUS AND SCIENCE GOALS v IN  0ROCEEDINGS  ,UNAR AND 0LANETARY  3CIENCE 8886))  (OUSTON  48  PP PDF    4 /NO  4 +OBAYASHI  AND ( /YA  h)NTERIM REPORT OF THE ,UNAR 2ADAR 3OUNDER ON 
 E. N.: A Fast Electronically Scanned Radar Receiving System, J. Brit. 
 Tolbert: Anomalies in the Absorption of Radio Waves by Atmospheric  Gases, Proc. IRE, vol. 48, pp. 
 TtlE RAOAR EQt JATION 63  WIIC'I c R,,,,, = rllaxirn\iiil I i~clar r i~ilge, III  C; = anterlna gain  :I = antenna aperture, 1n2  = antellrla elficiet~cy  rr = ntrmber of hits integrated  E,(rl) = integration efficiency (less than unity)  L, = system losses (greater than unity) not included in other parameters  (T = rictlar cross scction of target, rn2  F', = noise figure  k = Bolt7mann's constant = 1.38 x Jldeg  7, = standard tcrnpcrature = 290 K  B = receiver bandwidth. Hz  r = pulse widtli. s  1, = pulse repetition frequency, Hz  (SIN), = signal-to-noise ratio required at receiver output (based on single-hit  detection)  7'tiis equiitiorl car1 also he writtell ill terms of energy rather than power. 
 In addition, compensation for scattering from near-field aircraft  structure that distorts the antenna pattern and degrades AMTI performance can also be  performed with this adaptive circuitry, as can the adaptive nulling of external interference  sources.  For applications that cannot afford a fully adaptive array antenna, a design procedure can  he formulated that applies an optimal correction to an arbitrary receive array antenna pattern  hased on the use of a least-mean-squares algorithm to minimize the total clutter residue of an  I\ MTI radar averaged over all angtes.74  Sidelobes and pulse-doppler radar. Since the pulse-doppler radar is capable of good MTI  performance, it is also a good AMTI radar. 
 As the reader will discover in this chapter, these three  Seasat instruments established the initial paradigm for virtually all subsequent radars  of their respective classes.1,2Chapter 18 ch18.indd   1 12/19/07   5:13:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 
 The  one factor common to all true radar systems so far is our  knowledge of the speed of propagation of radio (electro-  magnetic) waves in space. Scientists and cynics take  some delight in the fact that we have discovered radar  and worked near miracles with it basically through our  knowledge that radio waves travel with a velocity of  186,240 miles a second; but we do not know anything  of the medium through which they travel (we call it  ‘ether’ for the want of a better understanding), and  there is, indeed, another school which believes that  there are no wave-like vibrations in this unknown ether,  but there is actual transmission of little packets of elec-  trical energy. Whatever it is, waves or spurts of electron  activity, something travels with a speed of 186,240 miles  a second, and for the purpose of radar measurements  that is all that we need to know. 
 .OISE 2ATIO ,/2/ ,OBING 
 Finally, the storm itself is evolving and  moving during this measurement time, thus complicating the data registration in space  and time. Some operational and many research applications require faster scanning than  conventional mechanically scanned radars can provide.155 These applications include  longer lead times for tornado warnings, the study of finer scale storm features, interac - tions between the internal motions and hydrometeor growth processes in the storms,  and studies of electric charge separation in clouds. Brook and Krehbiel156 were among  the first to discuss a very rapid-scanning radar (although nondoppler) for effectively  obtaining snapshots of convective storms. 
 2.54  Procedure for Range-De pendent Losses  ...........  2.54  Collapsing Loss  .................................................  2.54 Signal-Processing Losses  .................................. 
 This is true whether  or not the radar uses pulse compression. Prior to the development of modern clutter maps for controlling false alarms  caused by clutter residue, or the more recent suggestion that binary integration can  mitigate impulse-like residue,32 the use of IF limiting was essential for false-alarm  control in an MTI radar. Such limiting, however, seriously affects the mean improve - ment factor obtainable with a scanning-limited, multiple-delay canceler because of  the increased spectral spread of the clutter that exceeds the limit level. 
 Atthe recommended level of1to2mw ofmagnetron power theharmonics areatleast 20dbbelow thefundamental. Again control isundesirable; therefore, care incontrolling the r-fpower levels and in amplifier design isrequired forafoolproof AFC. The most frequent sources oftrouble areusually onther-fside rather than intheelectronic circuits, and arise from high power leakage into the crystal, faulty coupling tothemain line, orawrong amount ofattenuation. 
 and has a frequency range of 2900 to 3100 MHz. It issometimes more convenient to speak in terms of wavelength rather thanfrequency because of the high values associated with the latter. A fundamental requirement of marine radar is that of directional transmission and reception, which is achieved by producing a narrowhorizontal beam. 
 The angular error can be many times less than the beamwidth, depending upon  the value of EIN,. The accuracy formulas derived previously for the time delay and the  frequency nlay be readily applied to the determination of the angular error for various aper-  ture distributions.  The effective aperture width 11 for several aperture distributions which can be computed  ar~nlytic;~lly are giver1 below:  For A = O  nx D  A(x) = cos --- I x 1 < -- D 2  Inverse probability, likelihood ratio, and accuracy. 
    PP n   -AY . 
 £°£n  2!$!2 (!.$"//+  A MILITARY RADAR WITH LOW PROBABILITY OF INTERCEPT AT THESE FREQUENCIES THAN AT LOWER  FREQUENCIES )N THE PAST  MILLIMETER WAVE TRANSMITTERS WERE NOT CAPABLE OF AN AVERAGE POWER MORE THAN A FEW HUNDRED WATTSAND WERE USUALLY MUCH LESS !DVANCES IN GYROTRONS #HAPTER   CAN PRODUCE AVERAGE POWER MANY ORDERS OF MAGNITUDE GREATER THAN MORE CONVENTIONAL MILLIMETER 
 It has a frequency-response function which is proportional to the complex  conjugate of the signa1,spectrum. (This is not the same as the concept of" impedance match "  of circuit theory.) The ideal matched-filterreceiver cannot always be exactly realized in prac-  tice, but it is possible to approach.it with practical receiver circuits. A matched filter for a radar  transmitting a rectangular-shaped .pulse is usually characterized by a bandwidth B approxi-  mately the reciprocal of the pulse width 7, or Br = 1. 
 TIONS HAVE BEEN USED IN SOME COMMUNICATION TUBES  BUT THREE SECTIONS ARE MORE TYPICAL FOR HIGH 
 The noise generated bythe crystal increases with local-oscillator input. There isarather broad region of best over-all performance at0.5to1.0mw input which isacompromise between increasing noise athigh inputs and greater conversion loss at lowinputs. This optimum input corresponds tothewidely used standard operating point of0.5-ma d-ccrystal current. 
 Totake advantage ofthis essential difference between signal and noise itisevidently necessary toresort to some method ofinformation storage, orintegration, which would make useoftheinformation contained inseveral sweeps. Itmight bepossible, Time - (b) Time a (c) FIG. 2.6.—Output noise porrer: (a)single smeep; (b)average oftwosweeps; (c)average of foursweeps, forexample, toaverage over anumber ofs~veeps—that is,topresent to theobserver asingle trace whose height atany time would represent the average ofthe power output which was obtained ineach ofthe several sweeps atthat same time (measured from thetransmitted pulse). 
 11. A. Calioon. 
 This situation and others like it arethe result ofthe fact that very little research has been done onc-w systems incomparison with that devoted topulse systems. There arevarious reasons forthis comparative neglect ofc-wproblems, one of}vhich iscertainly valid. Allthe c-w systems tobedescribed have only asmall effective receiver bandwidth (asexplained inChap. 
 42 
 The second antenna atop the ASR-9  reflector (Figure 12.22) provides an inde - pendent tracking system. It is an Air Traffic  Control Radar Beacon System array antenna  that transmits and receives narrow azimuth  sum, difference, and guard beams, all shaped  in elevation. It requires a transponder aboard  the aircrafts targeted, as it has low gain. 
 175–194.  8. J. 
 23of this series. DESIGN OFAHIGH-PERFORMANCE RADAR FOR AIR SURVEILLANCE AND CONTROL 15.3. Initial Planning and Objectives. 
 The key requirements for this  paradigm are two: (1) an effective signal encoding that is very large and (2) an imag - ing environment that is dense and dominated by distributed random backscatter.  Planetary SARs (and many Earth-observing space-based radars) easily satisfy these  requirements. One measure of an imaging radar’s extensive signal encoding is the  product of its range and azimuth time-bandwidth products, or equivalently, its poten - tial two-dimensional compression ratio. 
 For example, it will limit the accuracy of elevation-angle measurement because of  the blockage of the fence and the error caused by the energy diffracted by the fence. Energy  diffracted by the fence also interferes with the direct path from the radar to cadse multipath  lobing of the radiation pattern in the angular region just above the fence. Radar energy  backscattered from the fence can sometimes be large enough to damage the receiver front-end  In one design, the fence was tilted 15" away from the radar to prevent this from happen~n~.~'  Fences also can serve to prevent high power densities from existing in areas where per-  sonnel might be l~cated.~' A fence can also suppress the ground-reflected multipath signal that  causes radiation-pattern lobing and elevation-angle errors, but the design of fences for this  purpose is different from the design of a clutter-suppression fen~e.~'.~~  13.7 EFFECTS OF WEATHER ON RADAR  On the first page of the first chapter it was stated that radar could see through weather effects  such as fog, rain, or snow. 
  
 PLER PROCESSING  A GIVEN DOPPLER FILTER MAY STILL INCLUDE CLUTTER RETURNS FROM A NUMBER OF DISCONTIGUOUS ANGULAR INTERVALS 4HE ADVANTAGES OF THIS TRANSFORMATION FROM 02) TO DOPPLER SPACE ON OVERALL 34!0 PERFORMANCE VERSUS A PRE 
 M RESOLUTION OVER A  
 LIKE TARGETS  OR FOR TARGETS SUCH THAT  O  D IS NOT SMALL COMPARED  TO K  ADDITIONAL TERMS SHOULD BE RETAINED IN %Q   DESCRIBING THE FACT THAT A SERIES  OF PAIRED ECHOES  OF DECREASING AMPLITUDE  MAY APPEAR IN CROSSRANGE &IGURE  SHOWS A 3!2 IMAGE OF A SCENE INCLUDING A VIBRATING TARGETA TRUCK  WITH ITS ENGINE RUNNING 4HE IMAGE CONTAINS TWO SETS OF PAIRED ECHOES  CORRESPONDING TO TWO VIBRATION FREQUENCIES CHARACTERISTIC OF THE PARTICULAR TRUCK USED FOR THE OBSERVATION -EASUREMENT OF /BJECT (EIGHT  4HE BASIC THEORY OF 3!2 ASSUMES THAT THE  SCENE IS FLAT 4O THE EXTENT  THAT THE SCENE IS NOT FLAT  DISTORTIONS IN THE 3!2 IMAGE WILL  RESULT )N SOME CASES  THEY CAN BE USED TO MEASURE THE HEIGHT OF ELEVATED OBJECTS ABOVE A FLAT TERRAIN &)'52%   3!2 SCENE CONTAINING VIBRATING TARGET #ROSSRANGE IS HORI 
 24.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 By suitable choice of the antenna gains, one may distinguish signals entering the  sidelobes from those entering the main beam, and the former may be suppressed.  Figure 24.1 a illustrates the radiation pattern of the main antenna together with a  low-gain auxiliary antenna. An implementation of the SLB processor is shown in  Figure 24.1 b, where the square-law-detected outputs of the two channels, ideally  identical except for the antenna patterns, are compared. 
 f+Ec. 62] DEJ’I.VITIOA-S 161 types, without attention tothe functional requirement which has called each into being, and without adescription ofthe technical means of realizing such indications. The latter subject isundertaken inChap. 
 78 HOW RADAR WORKS  valve radar time-base circuit works. It uses three high-  vacuum valves, and is stable over the wide frequency  range of 5 to 250,000 cycles per second. This upper  limit of frequency sweep is determined and limited, of  course, by circuit capacities and the voltage sweep  required, and not by any such irregular and unstable  factors as the deionization-time of a gas in a thyratron. 
    PP n  !PRIL   & * (ARRIS   -ULTIRATE 3IGNAL 0ROCESSING FOR #OMMUNICATION 3YSTEMS   5PPER 3ADDLE 2IVER  .*  0RENTICE (ALL     & (ARRIS  h/N THE USE OF WINDOWS FOR HARMONIC ANALYSIS WITH THE DISCRETE &OURIER TRANSFORM v  0ROC )%%%  VOL   NO   *ANUARY   PP n  * #OOLEY AND * 4UKEY  h!N !LGORITHM FOR THE MACHINE CALCULATION OF COMPLEX &OURIER SERIES v  -ATHEMATICS OF #OMPUTATION  VOL   NO   PP n  !PRIL . ÓÈ°£/ iÊ*À«>}>ÌÊ>VÌÀ]ÊÊ «]ÊÊÌ iÊ,>`>ÀÊ 
 WAVE STRUCTURE  SUCH AS A SMOOTH CIRCULAR TUBE    ONE WHERE THE PHASE VELOCITY OF THE  ELECTROMAGNETIC WAVE IS GREATER THAN THE VELOCITY OF LIGHT 7ITH A SLOW 
 FT ANTENNA  APERTURE &OR A SINGLE 
 ItlE (Lor~dor~) C'orlf.  Pirhl. no. 
 The output frequency is given by  fM ff N outclk=2φ (6.51) where  Mf = frequency word, input to the phase accumulator  fclk = phase accumulator clock frequency  Nf = number of bits of phase accumulator Linear FM or chirp waveforms are generated by applying a constant chirp slope  word (digitized chirp slope representation) to the input of the frequency accumulator,  creating a quadratic phase sequence at the output of the phase register. Piecewise-linear  or nonlinear FM waveforms can be generated by applying a time-varying slope input  to the frequency register. The frequency accumulator may be clocked either at the same  rate as the phase accumulator or at a sub-multiple to provide finer chirp slope resolu - tion. 
 A weighting function may  be assigned to each patch, and the problem is essentially solved when the amplitude  and phase of those functions have been determined. If the point of observation is forced down to a general surface patch, the fields on  the left sides of Eqs. 14.5 and 14.6 are those due to the contributions of the fields on all  other patches, plus the incident fields and a “self-field.” The self-field (or self-current or  self-charge) is moved to the right side of the equations, leaving only the known incident  field on the left side. 
 TRACK COVERAGE 4HE ALTIMETERS FOOTPRINT RESOLUTION SHOULD BE SMALLER THAN ABOUT  KM       ,ITERALLY  MEASUREMENT OF THE DISTANCE BETWEEN THE MEAN OCEAN SURFACE AND THE LOCAL SEA FLOOR&)'52%    7HEN AVERAGED AND STRIPPED OF  DYNAMIC CURRENT 
 76. Jordan. E. 
 K. Moore, “Theoretical scattering coefficients for near-vertical incidence from  contour maps,” J. Res. 
 VARYING WEIGHTS ARE GIVEN IN h3TAGGER $ESIGN 0ROCEDURESv IN 3ECTION   Ó°ÇÊ "*/ 1 Ê 
 G. Benjamin, B. E. 
 GATION FACTOR &OR EASE OF COMPUTATIONS IN EARLY SOLUTION TECHNIQUES  THE PROPAGATION FACTOR WAS OFTEN TAKEN AS UNITY  A CONDITION REPRESENTING FREE SPACE 7ITH COMPUTER 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.796x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 56. J. 
 TER 
 Thisphasedifference maybeusedasameasure oftheelapsedtime.Whenthetwo signalsslipinphaseby1cycle,themeasurement ofphase,andhencerange,becomes ambiguous. Thetwo-frequency CWradarisessentially asingle-target radarsinceonlyonephase dilTerence canbemeasured atatime.Ifmorethanonetargetispresent, theechosignal becomes ~omplicated andthemeaningofthephasemeasurement isdoubtful. Thetheoretical accuracy withwhichrangecanbemeasured withthetwo-frequency CWradarcanbefound. 
 Figure 8.18 a is a histogram of the peak time sidelobe level for the auto - correlation of every possible combination of a 15-bit code. Figure 8.18 b is the same  but for only maximal length sequences of  length 15 code (a subset of Figure 8.18 a).  Figure 8.18 a shows a lowest time sidelobe  level of –17.5 dB. 
 Images with random crop. ( a) Bulk Carrier image with random crop. ( b) Container ship image with random crop. 
 Thatis,theautomatic gaincontrol ismadetoactwithinthetimeofafewpulsewidths:TheIAGeactssomething likea pulse-width filter,permitting targetpulsestopassandattenuating thelongerpulsesfrom. clutter. Other means for attenuating long pulses from distributed clutter, yet pass the echoes  from point targets, include the Iiigli-pass filter atid various forms of pulse-width discriminators  that itihibit echo signals not of the correct pulse width. 
 of doppler cells 32–512 Max. velocity resolution (ms–1) < 0.5 Primary mission Ship detection Revisit time for entire coverage area Equal to CIT Secondary missions Aircraft detection Remote sensing Number of simultaneous targets tracked > 200 ch20.indd   72 12/20/07   1:17:13 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The fig - ures cited in Table 18.5 show that the ratio of waveform bandwidth to RF bandwidth  for TOPEX is on the order of 0.05%. The TOPEX altimeter design is described more  completely in the open literature.83,84 Geosat: Geodetic Mission.  Radar altimetric data are the basis for state-of- the-art gravimetric variations expressed at the ocean’s surface, and consequently,  oceanic bathymetry.* The principal objective of a geodetic satellite radar altimeter73  is to measure the (along-track) slope of the sea surface caused by gravity deflections  over spatial scales less than a few hundreds of kilometers (Figure 18.12). 
 ch02.indd   102 12/20/07   1:52:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 FORMS  BUT NOT SO FAR APART THAT THE ANGLE SUBTENDED AT THE TARGET IS MORE THAN ^ n  SO  THE SCATTERING BEHAVIOR IS CLOSE TO WHAT IS OBSERVED FOR EXACTLY MONOSTATIC GEOMETRY Óä°{Ê / 
 Ratioofmean-to-median crosssection forfog-normal distribution =p.. 52 INTRODUCTION TO RADAR SYSTEMS  performance for partially correlated pulses, interpolation between the results for the correlated  and uncorrelated conditions can be used as an approximation. A more general treatment  of partially correlated fluctuations has been given by Swerling." His analysis applies to a large  family of probability-density functions of the signal fluctuations and for very general correla-  tion properties. 
 Ataquarter- wave point the short circuit atthe coupling loop isreflected asanopen circuit and the piece ofline is,tothe local-oscillator frequency, astub support. Inmixers forthe 3-cm region, the crystal goes directly across the center ofthe guide. Coupling between local-oscillator waveguide and crystal guide isbymeans ofadjustable windows inthe short face ofthe guide. 
 BEAM CLUTTER FLUCTUATIONS ABOVE THE MEAN VALUE ALSO NEEDS TO BE CON 
 25.3 as the intersection of the two coverage circles and is ^c = vyV(4>* ~ sin Cf)7?) + rT2(j>T - sin <|>r)] (25.12) where $R and <|>r are shown on Fig. 25.3 and are ,/V-rr' + lA <fo = 2 cos'1 — (25.13)\ *rRL I JrT2-rR2 + L2\ 4>T = 2 cos"1 — (25.14)\ Lr1L / Terrain and other types of masking or shadowing degrade both monostatic and bistatic coverage. For ground-based bistatic transmitters and receivers the deg- radation can be severe.84 For this reason some air defense bistatic radar concepts use an elevated or airborne transmitter.44'45'48'54 As a general rule bistatic cover- age is less than monostatic coverage in both single and netted configurations. 
 216 THE EMPLOYMENT OF RADAR DATA [SEC. 7.2 ofdead-reckoning computers, orodographs, have been developed. The control box ofone such computer isshown inFig. 
 Proper selection of the nom- inal load impedance directly affects the power output, gain, insertion phase, ef- ficiency, and peak junction temperature of the single stage. Changes in the port- to-port insertion phase may result in combining inefficiencies among adjacent amplifiers since the RF power that is lost to the fourth-port termination of a mi- crowave combiner, when adjacent amplifiers are combined, is given by . TABLE 5.3 Performance Sensitivities for a Class-C-Biased Amplifier * Function of the saturation level. 
 QUANTIZATION LOBES FOR THE CASE SHOWN IN &IGURES  F AND  ARE GIVEN IN  &IGURE  !N EXAMINATION OF &IGURE  SHOWS THAT PEAK PHASE 
 Frequencies higher thanSbandareseldomusedforlong-range airsurveillance. High-power, largeantenna apertures, andgoodMTIareeasiertoachieveatfrequencies belowLband.Also,weather clutterismuchless.Thelowerthefrequency theeasieritisto obtainlongrange.However, atthelowerfrequencies, theazimuth beamwidths arebroader andtheavailable bandwidths arenarrower thanmightbedesired. BelowUHF,theexternal noiseincreases withdecreasing frequency andcanlimitreceiver sensitivity. 
 POWER AZIMUTHAL BEAMWIDTH  IN RADIANS  C IS THE SPEED OF PROPAGATION   MILLION  MS S  IS THE HALF 
 3   ELECTRONIC WARFARE %7   AND COMMUNICATION FROM THE SAME RADIO FREQUENCY 2&  HARDWARE AND PROCESS 
 25. Siegel, K. M.: Far Field Scattering from Bodies of Revolution, Appl. 
 The MC method assumes a mathematical model for the received signal. The model parameters (target radial velocity, acceleration) are achieved by the maximum contrast criterion of the image. It should be pointed out that the method requires two-dimensional search parameters at the same time and the computation is large [ 19]. 
 RESOLUTION  LOW 
 Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 22.2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 In the marine world, these have been called New Technology Radars . They are per - mitted to transmit any waveform at 3 GHz, providing the spectrum limitations on  marine radar are not exceeded.4 The limits have been agreed within the International  Telecommunication Union5 (ITU), a United Nations agency based in Geneva. 
 %66 %6*#2-! ! $RR   )T IS NOTED THAT THE OPTIMUM WEIGHT IS RELATED TO THE CORRELATION COEFFICIENT  Q BETWEEN  THE MAIN SIGNAL   6-  AND THE AUXILIARY SIGNAL   6! HIGH VALUES OF THE CORRELATION COEF 
 TION PROCESSING 4HE LOCATION OF THE LINE THAT SEPARATES THE TWO DOMAINS IS APPLICATION 
 ch04.indd   15 12/20/07   4:52:14 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 TRACK RESOLUTION  OF STACKED 'EOSAT  %23 
 BORNE  MOBILE  TRANSPORTABLE  AIR 
 POINT LINK STATISTICS AND VERTICAL INCIDENCE SOUNDINGS "OTH CLASSES ARE OF GENERAL APPLICABILITY TO (& COMMUNICATIONS AND GEO 
 Theoretically this is one of  those fascinating ideas which appear so simple that it  should surely have been immediately obvious to ‘them’  when ‘they’ were inventing radar! Yet the PPI repre-  sents the results of some years of work in radar and in  CRT development; and though it is now not difficult  theoretically, it nevertheless presented many tricky pro-  blems for the manufacturers of tubes for the system, and  it is still not easy to ensure that tubes stay accurate over  long operational periods.  When we look at a typical ground-radar station using  a PPI display we see a fascinating picture at the tube  end. We see, first, a translucent screen, squared off  probably in graticule fashion, and the centre of this is  not only placed over the centre of the CRT screen, but  represents geographically the position of our station. 
 Moore, and A. K. Fung37) ch16.indd   43 12/19/07   4:56:11 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Included are the antenna, receiver/exciter, signal processor, and data processor. The  radar’s control processor receives inputs from the on-board systems, such as the iner - tial navigation system (INS), and operator controls via the mission processor, and  performs as a master controller for the radar hardware. Coherent processing requires that all frequency down-conversions, including the  final conversion to baseband, retain the coherent phase relationship between transmit - ted and received pulses. 
 To extract SWH and WS from waveform data, finely tuned algorithms have been  developed and validated against in situ buoy measurements.63 For example, the  TOPEX Ku band altimeter measures SWH to within ±0.5 m up to more than 5.0 m and  WS within ±1.5 m/s up to more than 15 m/s. These figures correspond to averages over  1 second, or about 7 km, along the sub-satellite path of the altimeter’s footprint, which  typically is 3 km–5 km wide, determined by mean sea state. Flight Systems. 
 In this text a device for ohlaining a change of phase is called a rhasesh(fier, but they have  also been kn own as plwscrs.  I>i~itall~· switch{'() phase shifters. ;\ change in phase can be obtained by utilizing one of a  number of lengths of transmission line to approximate the desired value of phase. 
 Following are some use - ful expressions for the mean square error of mean power and mean velocity estimates. Power Estimation.  It is well known80 that for a gaussian random process using  square-law signal detection, samples of the mean power Pr of the process are expo - nentially distributed with variance Pr2.The variation is due to the process itself, not any  noise associated with the measurement. 
 Mains: Detection and Discrimination of Radar Targets, IEEE Trans., vol.  AP-23, pp. 358-367, May, 1975. 
 Instead of maintaining the frequency excursion  Af constant and obtaining a varying beat frequency, Af can be varied to maintain the beat  frequency constant. The beat-frequency amplifier need only be wide enough to pass the  received signal energy, thus reducirig the amount of noise with which the signal must compete.  The frequency excursion is maintained by a servomechanism to that value which permits the  beat frequency to fall within the passband of the narrow filter. 
   PP n  -ARCH   4 ! 7EIL  h!PPLYING THE !MPLITRON AND 3TABILOTRON TO -4)  RADAR SYSTEMS v IN  )2% .AT #ONV  2EC  VOL   PT   .EW 9ORK  .9    PP n. Ó°£äÓ  2!$!2 (!.$"//+   4 ! 7EIL  h!N INTRODUCTION TO -4) SYSTEM DESIGN v  %LECTRONIC 0ROGRESS  VOL   PP n    -AY   $ " ,EESON AND ' & *OHNSON  h3HORT 
 The stabilizing TEol  cavity is in the center of the magnetron with a vane-type resonator system arranged on the  outside. The cathode is built as a ring surrounding the anode. Power is coupled from the end of  the central stabilizing cavity by a circular waveguide. 
 An expression for the resolution achievable in the focused case has been given as Eq. (21.8). It is significant that the azimuth resolution achievable for this case depends only upon the physical antenna aperture and that, in contradistinction to the conventional case, fine resolution requires the use of small rather than large antennas. 
 when homing onto a target (see discussion on Vixen for ASV Mk. II in chapter 2). The increased power should have increased the noise-limited range of the radar by a factor of about 1.5. 
 ON   2#3  D"SM "LUE 
 73 ----.,F.....—, ‘:1 Fixer I Developer FIQ,77—Rapid photographic PPIprojector,. SEC. 7.3] AIDS TO PLOTTING AND CONTROL 223 Video Mapping—None ofthe methods sofardescribed permits the superposition ofan“electronic” map onthe dk,play. 
 The orientation of the ELECTRIC AXIS in spaceestablishes what is known as the POLARIZATION of the wave. Horizontalpolarization is normally used with navigational radars, i.e., the direction ofthe electric axis is horizontal in space. Horizontal polarization has been found to be the most satisfactory type of polarization for navigational radarsin that stronger echoes are received from the targets normally used withthese radars when the electric axis is horizontal. 
 ERN RADARS 4HE TRACKER CREATES WINDOWS  OR GROUPS OF CONTIGUOUS RANGE 
 For example, an unknown 1 ° slope  would lead to a 120-m surface height error, which is unacceptable if cm-level inter- annual changes are the objective. The CryoSat altimeter90 is the first space-based radar altimeter designed to oper - ate over ice (Figure 18.13). Its payload instrument is the SAR/Interferometric Radar  ALtimeter (SIRAL), which has three modes: Conventional, SAR, and Interferometric. 
 8.2. in order to generate a beam at some angle 00, there must be a relative phase difference  hctween adjacent elements equal to ¢ 21t(d/,.l) sin 00• If the leCt-hand element of an N­ clcment linear array is taken as the reference, then the phase shifters at the other elements must  have values of¢. 2¢ .... 
 The second stage hasagain control inthecathode tocompen- sate forvariations ininput-signal amplitude. The amplified signals drive the grids ofthe 8025 r-fpower amplifiers through acathode follower. Since thebias forthecathode follower must remain constant forallduty ratios, ad-crestorer isused between itsgrid and the —105-volt supply. 
 3. 4.Signals capable ofcontrolling anelectromechanical repeater. The repeater can bcused toposition acathode-ray-tube coil orto provide adummy scanner shaft towhich the final data trans- mitters areattached. 
 , vol. 23, pp. 282–332,  1944; pt. 
 PLANE  DATA IS SHOWN IN BOLD TYPE ON THE TABLE /UT 
 WINDOW DETECTOR IN LOG 
 F., and M. A. Corbin: Radar Refleclivity of Airborne Insects. 
 The primary IQM for most SARs is the width (meters) of the PSF mainlobe at  its “half-power points,” or points where the intensity (power, proportional to voltage  squared) is one half, or −3 dB, relative to the mainlobe peak. This IQM is typically  referred to as the “3-dB width.” To obtain fine resolution in either range or crossrange, a Fourier transform (FT) is  performed on a set of collected data. Since all data samples have essentially the same  magnitude, for either range or crossrange we essentially perform a FT on a rect - angular function, which produces a ( sinc)2 function ( sin(x)/x)2, with a 3-dB width  of (0.886) dpn (where dpn = peak-to-first-null interval) and a first sidelobe –13.3 dB  below the peak. 
 Hansen (ed.). Academic Press, N.Y .. 1966. 
 DELAY 
 5.10. Inspection ofthe last two figures will show that, forradar systems ingeneral, there isno“usual” case. One may perfectly well have either sign ofthe inequality. 
   3/,)$ 
 Widrow for pioneering work on adaptive signal processing, see Etter et al.91 The  theory and application of adaptive array principles to radar is well established; for  a look to popular publications see, for instance, Haykin and Steinhardt,92 Smith,93  and Farina et al.94 The basic result is given by the expression of the optimum set  of weights:  ˆW M S*=−µ1 (24.6) where M = E(V*VT) is the N-dimensional covariance matrix of the overall disturbance  (noise and jammer) V received by the array, and S is the N-dimensional vector con - taining the expected signal samples in the array from a target along a certain direction  of arrival. The similarity of Eq. 24.6 to Eq. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas.  REFLECTOR ANTENNAS  12.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 Multiple reflector systems, typified by the Cassegrain antenna shown in  Figure 12.15 f, offer one more degree of flexibility by shaping the primary beam and/ or allowing the feed system to be conveniently located behind the main reflector. 
 Andrews. G. A., Jr.: Performance of Cascaded MTI and Coherent Integration Filters in a Clutter  Environment. 
 SPACE  SEARCHES FOR AIR TARGETS TO ATTACK  AND ULTIMATELY RETURNS TO THE STARTING POINT !LONG THE WAY  THE AIRCRAFT USES A VARIETY OF MODES TO NAVIGATE EXCHANGE DATA WITH COMMAND  CONTROL  COMMUNICATIONS  INTELLIGENCE  SURVEILLANCE  4!",%  4YPICAL 7AVEFORM 0ARAMETERS ! 
 SIGHT VELOCITY MEASUREMENT   6 ,/3  USING DOPPLER  ANDOR RANGE RATE  IS MADE ALSO USING CENTROIDING "ECAUSE TERRAIN MAY BE RISING OR FALL 
 ITY TO DISCRIMINATE SIGNAL FROM GROUND CLUTTER  OTHER ARTIFACTS  AND NOISE  AND TO ESTIMATE METEOROLOGICAL PARAMETERS OF INTEREST -OST FREQUENCY DOMAIN PROCESSING REQUIRES RELATIVELY LONG )1 DATA SAMPLE SETS FOR DISCRETE &OURIER TRANSFORM ANALYSES  WINDOW FUNCTIONS  AND POSSIBLE SPECTRAL AVERAGING TO OBTAIN SPECTRA SUITABLE FOR QUANTITA 
 The gain G of an antenna is a measure of the increased power radiated in  the direction of the target as compared with the power that would have been radiated from an  isotropic antenna. It may be defined as the ratio of the maximum radiation intensity from the  subject antenna to the radiation intensity from a lossless, isotropic antenna with the same  power input. (The radiation intensity is the power radiated per unit solid angle in a given  direction.) The power density at the target from an antenna with a transmitting gain G is  Pt G Power density from directive antenna = - 4nR2  The target intercepts a portion of the incident power and reradiates it in vqrious directions. 
 If the jamming is severe enough, CFAR can produce almost the same effect as turning  off the receiver. In a jamming environment, it can lull the radar operator into a false sense of  security since the ideal CFAR, by maintaining the output noise level constant no matter what  the level of the input noise, provides no indication that jamming is present. Additional means  must be incorporated into a CFAR to provide the operator with warning of the presence of  noise jamming. 
 ,Ê , / 
 7.  101. Graf, G.: On the Optimization of the Aspect Angle Windows for the Doppler Analysis of the Radar  Return of Rotating Targets, IEEE Trans., vol. 
 The  bar over I', denotes that the rcccived power is averaged over many independent radar sweeps  to smooth tk signal fluctuations. This equation assumes that the volume of the antenna  resolutiori cell is completely filled wit11 uniform precipitation. If not, a correction must be  lr~ade by iritroducit~g a dinietisionlcss beam-fillil~g factor IC/ wliic11 is the fraction of the cross-  sectional area of the beam intercepted by the region of scattering particles. 
 A study34 compared the resolving capability of three common detection proce - dures: linear detector with T A= +ˆ ˆµ σ , linear detector with T B=ˆµ, and log detector  with T C= + ˆµ, where the constants A, B, and C are used to obtain the same Pfa for  all detectors. The estimates ˆµandˆσof m and s were obtained from either (1) all the  reference cells or (2) the leading or lagging half of the reference cells, choosing the  FIGURE 7.21  Modified generalized sign test processor ( after G. V . 
 ALTITUDE REGION OF INTEREST FOR SKYWAVE PROPAGATION   AND IT IS ALSO THE REGION OF GREATEST ELECTRON DENSITY )N THE DAYLIGHT HOURS  THE & REGION SOMETIMES MANIFESTS TWO COMPONENT LAYERS  ESPECIALLY IN SUMMER 4HE &L REGION LIES BETWEEN  AND  KM AND  LIKE THE % REGION  IS DIRECTLY DEPENDENT UPON SOLAR RADIATION IT REACHES MAXIMUM INTENSITY ABOUT  H AFTER LOCAL NOON 4HE & REGION IS VARIABLE IN BOTH TIME AND GEOGRAPHICAL LOCATION 4HE ALTITUDE OF THE & REGION PEAK LIES TYPICALLY BETWEEN  AND  KM AT MIDDLE LATITUDES 4HE & 
 Hard-tube modulator.lThehard-tube modulator isessentially ahigh-power videopulse amplifier. Itderivesitsnamefromthefactthattheswitching isaccomplished with"hard­ vacuum" tubesratherthangastubes.Semiconductor devicessuchastheSCR(silicon­ controlled rectifiers) canalsobeusedinthisapplication.1Therefore, thenameactive-switch modulator issometimes usedtorenectthefactthatthefunction ofahard-tube modulator can. 216 INTKODUCTlON TO KADAR SYSTEMS  be obtained without vacuum tubes. 
 88, pp.  485-495, 1962.  70. 
 Thustherecanbe manydemands placeduponthereceiver designer inmeeting therequirements ofmodern high-quality radarsystems. Thereceiver engineer hasresponded welltothechallenge, and thereexistsahighlyrefinedstateoftechnology available forradarapplications. Radarreceiver designandimplementation maynotalwaysbeaneasytask;butintributetothereceiver designer, ithasseldombeenanobstacle preventing theradarsystems engineer fromeventually accomplishing thedesiredobjectives. 
 Software- defined Radar sensors will make microwave remote sen sing more affordable in the future. The  functionality may even be user -implemented.  One should not be afraid of this dramatic yet e x- pected change in our research field in the f uture. 
 PUTE THE IMPACT POINT OF A LAUNCHED MISSILE CONTINUOUSLY DURING THE LAUNCH PHASE IN CASE OF MISSILE FAILURE FOR RANGE SAFETY )F THE IMPACT POINT APPROACHES A POPULATED OR OTHER CRITICAL AREA  THE MISSILE IS DESTROYED -ISSILE 
 ENCE CAN RESULT IN POOR LOW 
 Kuroiwa, M. Kojima, K. Oikawa, H. 
 The following two expressions have been suggested  Measurements show a correlation between surface temperature and the coefficient a of the  Z = arb relationship, which suggest the following76  Z = 1050r2 for dry snow (ave temp. < WC) (1 3.26a)  Z = 1600r2 for wet snow (ave temp. > 0°C) ' (13.26h)  A lower surface temperature results in a lower value of the coefficient a. 
 Inaddition, compensation forscattering fromne'ar-field aircraft structure thatdistorts theantenna patternanddegrades AMTIperformance canalsobe performed withthisadaptive circuitry, ascantheadaptive nullingofexternal interference sources. Forapplications thatcannotaffordafullyadaptive arrayantenna, adesignprocedure can heformulated thatappliesanoptimal correction toanarbitrary receivearrayantenna pattern hasedontheuseofaleast-mean-squares algorithm tominimize thetotalclutterresidueofan AMTIradaraveraged overallangles.14 Sidelobes andpulse-doppler radar.Sincethepulse-doppler radariscapable ofgoodMTI performance, itisalsoagoodAMTIradar.However, iftheantenna sidelobes arenotlow,the clutterthatenthstheradarviathesidelobes canlimittheimprovement factor,asmentioned previously [Eq.(4.40)].Theeffectofthesidelobe cluttermustoftenbeconsidered inthedesign ofthesignalprocessor ofanairborne pulse-doppler radar. Thespectrum ofthesignalreceived byanairborne pulse-doppler radarmightappearas inFig.4.36.Onlythatportion ofthespectrum inthevicinityofthecarrierfrequency fois shownsincetheprfofapulse-doppler radarischosentoavoidoverlapoftargetsignalsfrom adjacent spectral lines(noblindspeeds). 
 2ICE SOLU 
 PULSE  FINITE IMPULSE RESPONSE &)2  FILTERS USED IN THE !32 
 ∑ ∑∑∑∑ ∑∑∑ . +β ·α :LCUT 3 2 1   Figure 12.5  Principle of the CASH -CFAR circuit.   The CASH- CFAR (C ell Averaging Statistic Hofele [1- 2]) comprises essentially a shift re gister  configured by “A” sub -registers, each having its own adder and containing L storage cells. 
 1223-1231, October, 1952.  13. Urkowitz. 
 It may be written as W(K, 0), where K is the wavenumber for the surface.  In terms of the wavelength on the surface Λ,  K = 2p/Λ  FIGURE   16. 6b In-phase addition for Bragg scattering: ∆R = nl/2 ch16.indd   11 12/19/07   4:54:50 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Similar color distribution characteristics can be found in the ﬁgure, with Zhongxinhe Road as an obvious boundary. The detected subsidence rate in the upper region was relatively obvious, with maximum value of 67 mm /y, whereas the area below Zhongxinhe Road was more stable, with the deformation velocity generally lower than 10 mm /y. Figure 8d shows the overall distribution of height corrections, and the results are generally within the interval of [−50, 40 ]m, with a maximum DEM error of 95 m. 
 pp. 166 1- 1701, December, 1974.  27. 
 BOARD A CASE STUDY FOR RADAR APPLICATION v  0ROC OF THE TH  %UROPEAN -ICROWAVE #ONF  "OLOGNA )TALY   3EPTEMBER n    PP n  ! $!CIERNO  - #ECCARELLI  ! &ARINA  ! 0ETROSINO  AND , 4IMMONERI  h-APPING 12  DECOMPOSITION ON PARALLEL COMPUTERS A STUDY CASE FOR RADAR APPLICATIONS v  )%)#% 4RANS ON  #OMMUNICATIONS  VOL %n"  NO   PP n  /CTOBER   ! &ARINA AND , 4IMMONERI  h0ARALLEL PROCESSING ARCHITECTURES FOR 34!0 v IN  !PPLICATIONS OF  3PACE 
 D. Klein, and H. A. 
 R. P. Perry, R. 
 Inconsequence oftheradial motion ofthetarget, which wesuppose tobeatconstant velocity v,,the phase ofthe returned signal, relative fTarget + - FI~. 6.1.—Simplest possible radar system, using single transmitted frequency, with modulation derived from target motion. tothe outgoing one, shifts continuously. 
 106. The Early History ofRadar.—Though the complete history of theorigins and thegrowth ofmodern radar isalong and complicated one, 1 itwill beofsome interest tosketch here itsmain lines, with especial reference toAllied developments. Successful pulse radar systems were developed independently in America, England, France, and Germany during thelatter 1930’s. 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing.  RADAR DIGITAL SIGNAL PROCESSING  25.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 to time-domain multiplication of a uniform impulse train at the 50 MHz sampling  frequency with the signal represented by line 5. In the time domain, the result is a  50 MHz train of sampling impulses with areas that are (give or take a scale factor that  we are ignoring) samples of the line 5 signal at the sampling instants. 
 REFLECTOR TRANSFORMATIONS AND AREA PROJECTIONS   4HE RESULTANT APERTURE FIELD  &V}   IS THEN TRANSFORMED TO THE FAR FIELD USING THE  SPATIAL TRANSFORMATION  &V & XY EJXI YIXY}     }}}    u GRIDP LV V XY £   . £Ó°È  2!$!2 (!.$"//+  WHERE}VIS A UNIT VECTOR IN THE DIRECTION OF INTEREST .OTE THAT %Q  IS A SIMPLE $  SPATIAL SUMMATION ANALOGOUS TO THAT USED FOR ARRAY ANTENNA PATTERN CALCULATIONS 4APER %FFICIENCY  )N ANTENNA DESIGN  APERTURE TAPER IS USED TO LOWER SIDELOBES  4HE MODEST RESULTANT LOSS AND INCREASED BEAMWIDTH IS THE PRICE AND ONE IS USUALLY  WILLING TO PAY TO OBTAIN THE DESIRED SIDELOBE LEVEL 4HE LOSS ASSOCIATED WITH APERTURE TAPER IS ACCOUNTED FOR IN THE TAPER EFFICIENCY (OWEVER  THE TAPER EFFICIENCY IS NOT AN OHMIC LOSS WHERE ENERGY IS DISSIPATED  BUT IS A REDISTRIBUTION OF ENERGY )N THE CASE OF A REFLECTOR FED BY A HORN   THE TAPER DISTRIBUTION IS DETERMINED BY THE FEED HORN PATTERN   THE DISTANCE TO THE REFLECTOR  AND THE PROJECTED AREA IN THE DIRECTION OF PEAK RADIATION &OR A RADIALLY SYMMETRIC FEED AND REFLECTOR  WHERE THE FIELD IS RADIALLY SYMMETRIC AND & GRIDX Y    GR   THE EFFICIENCY  G  IS COMPUTED AS  HP PP ¯ ¯ ¯GR RD R GR R D R R D R         3PILLOVER ,OSS  3PILLOVER LOSS REFERS TO FEED POWER THAT MISSES  OR SPILLS OVER  THE   EDGES OF THE REFLECTOR )N THE RADAR REFLECTOR DESIGN PROCESS  ONE TYPICALLY ADJUSTS THE EDGE ILLUMINATION TO ACHIEVE A DESIRED TAPER AND SIDELOBE LEVEL RESULTING IN MODEST SPILLOVER LOSS 3PILLOVER LOSS IS THE FEED POWER THAT IS LOST VIA RADIATION BEYOND THE EDGES OF THE REFLECTOR 4HIS LOSS CAN BE COMPUTED AS  3PILLOVER,OSS 4OTAL&EED0OWER&EED0OWER 
 Decoys mightbecarriedonboardattacking bomber aircraftandlaunched outsidethe normalradardetection ranges.Sincedecoyscanbemadetocloselyresemble realtargets,and sinceadecoymightconceivably carryabomb,onedefensive strategy wouldbetodestroyall unfriendly targets,including knowndecoys. Reducing theradarcrosssectionofthetargetbypropershaping isanother possible passivecountermeasure. Atargetwithdoublycurvedsurfaces (curvature intwodimensions) willhavesmallcrosssection.Itshouldnothaveanyflat,cylindrical, orconicalsurfaces which mightbeilluminated bytheincident radarwavefromadirection alongthenormaltothe surface.Thecone-sphere, described inSec.(2.7),isagoodexample ofatargetshapethatyields alowvalueofcrosssectionoverawiderangeofangles. 
 PULSE STAGGERING  HOWEVER  IS  ONLY  
 Receiver noisegenerally limitsthcsensitIvIty ofmostmicrowavc radars. Raisingthenoiselevelbyexternal means,aswithajammcr, furthcrdegrades thescnsitivity of theradar.Noiseisafundamental limitation toradarperformancc andthcreforc canhean effective countermeasure. TheECCMdesigncr mustminimizc theamount ofnoiseajammer canintroduce intotheradarreceiver.Itisdifficult, however, tokeepthenoiseoutwhenthe jammer isbeingilluminated bythemainbeamoftheradarantenna. 
 26. Lo, Y. T.: On the Beam Deviation Factor of a Parabolic Reflector, IRE T,a11s., vol. 
 Then, only those reference cells which are in the noise field containing the test cell are used to calculate the adaptive threshold.MAXIMUM JAMMING/NOISE * 2OdB N = 6 PULSESPROBABILITY OF DETECTION . SNR (dB) FIG. 8.18 Detection probability versus SNR for Swerling Case 2 primary target. 
 OF 
 Choice ofSystem Constants.-The following aretheobjectives inthedesign ofaground radar setwith MT1: 1.Ylaxlmum sensitivity tomoving targets intheclutter. 2.Maximum sensitivity tomoving targets intheclear. 3.Maximum cancellation ofundesirable moving objects, such as clouds. 
 TROLLED TO BE LESS THAN THE SYSTEM DYNAMIC RANGE  THEN THE SYSTEM DYNAMIC RANGE SHOULD BE DECREASED !N ALTERNATIVE TO DECREASING THE DYNAMIC RANGE IS TO DEPEND ON A CELL 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Radar Transmitter.  THE RADAR TRANSMITTER  10.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 the attention of radar engineers until the announcement in a paper in the November  1953 Proceedings of the IEEE  by Stanford University engineers of the development  of an S-band multicavity klystron capable of 20 MW peak power and 2.4 kW average  power for use in a linear accelerator. 
 Although the noise figure of a mixer front-end may not be as low  as other devices that can be used as receiver front-ends, it is acceptable for many radar  applications when other factors besides low noise are important. The function of the mixer is  to corlvert RF energy to IF energy with minimum loss and without spurious responses. Silicon  poin t-con tact and Schot tky-barrier  diode^'^.'^ based on the nonlinear resistance character-  is tic of metal-to-semiconductor contacts have been used as the mixing element.4.5 Schottky-  barrier tliodes are made of either silicon or GaAs, with GaAs preferred for the higher  microwave frequencies. 
  32 
 The relative priorities of ASV, AI, CH (chain home) and CHL (chain home low) development were discussed at a meeting on 30th November 1939 in the Air Ministry, attended by Air Marshal SirPhilip Joubert de la Ferté, Air Of ﬁcer Commanding-in-Chief Coastal Command, and Vice Admiral Sir James Somerville, representing the Admiralty [ 3]. It was agreed that ASV would be installed in 12 Hudsons to operate the northern patroland that work should recommence on ASV for Sunderlands with the highest priority. Urgent production contracts were placed with Pye Radio for 200 ASV receiver/indicators and with E K Cole for 200 transmitters. 
 It also depends on the inverse of the system noise  temperature, but this is of little consequence since the noise temperature is not a major  design issue anymore. The situation is more complex when the target to be detected  is of the stealth type.149 Waveform design and operating frequency are relevant parameters in tactical and  volume surveillance radars, which must be able to detect low-flying penetrating tar - gets that attempt to use terrain-shielding effects to escape radar detection. In this case,  the selection of waveform and frequency is made to tackle the problems of masking,  multipath, chaff, clutter, and ECM.134,138,150 The major EW threats to a surveillance radar are (i) noise jamming, (ii) chaff,   (iii) deception jamming, (iv) decoys and expendables, and (v) ARM. 
 DOWN VIEWING GEOMETRY INEVITABLY RESULTS IN STRONG GROUND ECHOES AT THE SAME RANGE AS THE TARGET  TYPICALLY n D" STRONGER THAN THE TARGET ECHO $OPPLER PROCESSING 7IDELY USED FOR DETECTION  OF MOVING TARGETS IN CLUTTER%SSENTIAL TO SEPARATE MOVING TARGETS FROM STRONG CLUTTER RETURNS4!",%  +EY $IFFERENCES "ETWEEN -ICROWAVE 2ADAR AND (& 3KYWAVE 2ADAR   4HE PARAMETER VALUES QUOTED HERE ARE INTENDED TO BE BROADLY REPRESENTATIVE  RATHER  THAN AN ATTEMPT TO SPAN ALL KNOWN SYSTEMS . 
 STAGE #)# DECIMATOR 4HE FILTER CONTAINS AN INTEGRATOR  STAGE CONSISTING OF A SINGLE SAMPLE DELAY AND AN ADDER  FOLLOWED BY A COMB STAGE WITH A $ 
 L. Hess et al., “Delineation of inundated area and vegetation along the Amazon floodplain  with the SIR-C synthetic aperture radar,”  IEEE Trans. on Geosc. 
 Hence those methods may have to cope with the entire raw dataset. The invalid data would occupy a massive amount of computation time when processing all the raw data. The other is that there may be a few ship targets with different motions in the raw data. 
 DETECTORS AND PHASE 
 power. Two radars with the same subclutter visibility might not have the same ability to  detect targets in clutter if the resolution cell of one is greater than the other and accepts a  greater clutter signal power; that is, both radars might reduce the clutter power equally,  but one starts with greater clutter power because its resolution cell is greater and "secs"  more clutter targets.  Clutter visibility factor. 
 130. Bovey, C. K., and C. 
 Inertial sensors are extremely good over  short span times, but velocity drift is a major long-time error source, e.g., 1 km/h  accumulates 16.6 m error per minute. A radar mode may require position to 0.1 km  for proper operation. PVU generally uses three or more antenna beam positions in which it makes a  velocity measurement, as shown in Figure 5.31.15 This mode directly emulates dedi - cated radar doppler navigators. 
 RANGE RESOLUTION AND SAMPLED AT A SUFFICIENT NUMBER OF ANGLES OVER THAT SECTOR )N PRACTICE  THE TARGET IS ROTATED CONTINUOUSLY WHILE THE SWEPT 
 37. Shi, S. Shear strength, modulus of rigity and young’s modulus of concrete. 
 Equation (3.11)maybewrittenas ...... eN .,.,.R=4t1f (3.13). WIICIC I< - I;III~~ (i~Itit\t<l~). 
 TO 
   8. 
 BEAM TUBES  ARE LIGHTER IN WEIGHT AND SMALLER IN SIZE  AND HAVE BEEN FOUND FROM 5(& TO + BAND (OWEVER  THEY HAVE RELATIVELY LOW GAIN AND THEIR STABILITY AND NOISE ARE NOT AS GOOD AS FOUND IN LINEAR 
 F. George, and 0. D. 
 and i•  one phase shifter for each of the M columns to achieve steering in the orthogonal plane.  Changing the frequency of a signal propagating through a length of transmission line is  a convenient method for obtaining a phase shirt, but it is not always desirable to operate a  radar with a changing frequency. A phase shifting technique that uses a frequency change, but  which then converts back to a constant frequency, is the Huggins phase shifter shown in  Fig. 
 BEAM WIDTH MIGHT BE INCREASED TWO TO THREE TIMES )N ADDITION  MOST OPERATIONAL RADARS DO NOT USE ULTRALOW LESS THAN  
 AES-9, pp. 237-252,  March, 1973.  147. 
 Def. Expo '78, Wiesbaden, Germany, 1978. 8. 
 Then the asteroid’s speed in the solar system varies from 17.9 km /st o4 2k m/s. In order to analyze and realize localization, navigation and imaging properties of pulsar emissions, adequate mathematical models need to be built, which is one of the goals of the present research. From point of view of pulsar emissions utilization, including localization, navigation and imaging, the most appropriate emissions are those from Crab Nebula pulsar. 
 7.THE ElfPLO~31ENT OFRADAR DAT.k 213 7.1 The Signal andItsLTse. .213 EXTERNAL A1nSTORADAE ~-SE. 214 7.2 Aids toIndividual A’avigation. 
 Hastings, C. E.: Raydist: A Radio Navigation and Tracking System, Trle-Teclr, vol. 6, pp. 
 MALLY ACTS AS BOTH RADAR AND ELECTRONIC CHART 4HESES DISPLAYS ARE ALL EFFECTIVELY -&$S AND CAN  THEREFORE  ALSO BE USED AS AN ELECTRONIC CHART SYSTEM WITHOUT RADAR INPUT ÓÓ°ÇÊ  / 
 Freeman, “Simple MTI using synthetic aperture radar,” in Proceedings of IGARSS 1984  Symposium , ESA SP-215, 1984. 40. A. 
 INDUCED MOTIONS CAN PRODUCE UNCOMPENSATED ERRORS IN RADAR 
 ANGLE REGIME THAN THESE MODELS  ALTHOUGH FORESTS AND SIMILAR ROUGH TARGETS OF SOME DEPTH SOMETIMES GIVE SUCH SLOWLY VARYING RETURNS. £È°n  2!$!2 (!.$"//+  3INCE THESE ROUGH 
 G.: Bistatic Clutter in a Moving Receiver System, RCA Rev., pp. 518-540, September 1969. 76. 
 TUDE TO THE RMS VALUE OF THE !$ CONVERTER NOISE PLUS DISTORTIO N 4HE NOISE PLUS DIS 
 Because of the limited vertical aperture extent of the AN/ APY-I radar, the elevation beam is relatively broad. Consequently the height ac- curacies achieved by the radar do not compare well with those of its surface- based counterparts. *The term multipulse is used by the author to refer to a target angle estimation technique discussed in Sec. 
 ch02.indd   90 12/20/07   1:47:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 In addition, all detection ranges reported are taken from operator observations. The skills and attention spans of operators varied greatly and added to the uncertainty of theresults obtained. The radar noise-limited sensitivity was routinely tested by CCDU against Grassholm Island, ﬂying at a height of 1000 ft. 
 FIG. 24.1 At the upper left an example of single-hop sky-wave propagation with the useful cov- erage in range is sketched. On the upper right extended range coverage is obtained by using three frequencies. 
  
 4.8 Lll\tllTATIONS TO MTI PERFORMANCE  The improvemenl in signal-to-clutter ratio or an MTI is affected by factors other than the  design of the doppler signal processor. Instabilities or the transmitter and receiver, physical  motions of the clutter, the finite time on target (or scanning modulation), and limiting in the  receiver can all detract from the performance of an MTI radar. Before discussing these effects,  some definitions will be stated. 
 The image quality of the proposed method result is better than the original image, DCT and PGA results. The cross-range of the image is well-focused and 284. Sensors 2019 ,19, 1154 blurred regions are reduced in Figure 6d. 
 100. H. Steyskal, “Digital beamforming antennas: an introduction,” Microwave J ., pp. 
 PROCESSING  FUNCTIONS (ARD LIMITERS WITH AS MUCH AS  D" OF LIMITING RANGE WERE USED WITH SOME DESIGNED TO LIMIT ON 
 TO 
 A bank of dispersive filters are needed to cover the angular  sector, as described in Sec. 8.4. Each filter would be designed to accommodate the spread of  frequencies expected from a particular elevation angle. 
 49. Treffeisen et al., “Obstacle Clearance System for Aircraft,” U.S. Patent 3,530,465, 9/22/1970. 
 19.Rlake.L.V.:RayHei~htComputation foraContinuous Nonlinear Atmospheric Refractive-Index Profile.Radio SC;I'II('I'.vol.).pp.R592,January. 1968. 20.Bean.B.R.andB.A.Cahoon: TheUseofSurfaceWeather Observations toPredicttheTotal Atmospheric Bending ofRadioRaysatSmallElevation Angles,Proc.IRE,vol.45,pp.1545-1546, November. 
 This value is for isotropic radiators and is reduced if the radiators have directivity. Linear Array.39 With a linear array of N isotropic radiators, excited with equal amplitudes and phase and separated by distances s, as shown in Fig. 7.5, the condition for the occurrence of grating lobes is unchanged from the simpler case just considered. 
 Thevoltage envelope lof·Fig.2.1.isassumed tobefromamatched-filter receiver (Sec.10.2).Amatched filterisonedesigned tomaximize theoutputpeaksignaltoaverage noise(power)ratio.Ithasafrequency-response function whichisproportional tothecomplex conjugate ofthesignalspectrum. (Thi.sisnotthesameastheconceptof"impedance match" ofcircuittheory.)Theidealmatched-filter· receivercannotalwaysbeexactlyrealizedinprac­ tice,butitispossibletoapproach itwithpractical receivercircuits.Amatched filterforaradar transmitting arectangular-shaped .pulseisusuallycharacterized byabandwidth Bapproxi­ matelythereciprocal ofthepulsewidthf,orBr;:::1.Theoutputofamatched-filter receiver is. Threshold level , A  Time -  Figure 2.1 Typical envelope of tile radar receiver output as a function of time. 
 Sometimes bothconditions cannot·hemetsimultancously andacompromise isnecessary. Theuppercutofffrequency is selectcdtopassthchighcstdoppler frequency expected. Theindicator mightbeapairofearphones orafrequency meter.Ifexactknowledge ofthe doppler frequency isnotneccssary, earphones areespecially attractive provided thedoppler frequencies liewithintheaudio-frequency response oftheear.Earphones arenotonlysimple devices. 
 The reduction in intensity as the rays diverge (spread away) from the point of reflection can be calculated from the curvatures of the reflecting surface and the incident wave at the specular point, that point on the surface where the angle of reflection equals the angle of incidence. The principal radii of curvature of the surface are measured in two orthogonal planes at the specular point, as shown in Fig. 11.24. 
 Institut für Hochfrequenztechnik  und Elektronik   Mail Address: Institut für Hochfrequenztechnik und Elektronik Phone: +49 (0) 721 608 25 22  Kaiserstraße 12 Secr.: +49 (0) 721 608 25 23  D-76131 Karlsruhe Fax: +49 (0) 721 69 18 65   E-Mail: ihe@ihe.uka.de Building: Engesserstraße 5, Geb. 30.10 www.ihe.kit.edu   Lecture Script      Radar Systems Engineering  by Werner Wiesbeck                16th Edition WS 2009/2010 . Radar System Engineering  Contents  i     Contents   1 The History of Radar Technology ......................................................................................... 
 Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 14.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 Common calibration targets include metal spheres, right circular cylinders, flat plates, and  corner reflectors. The radar cross sections of these objects may be calculated by using the  expressions given in Section 14.3. 
 135–139,  December 1956. 17. D. 
 This is illustrated in Figure 3.1.   Target Transmit Antenna  GainGT Receive Antenna GainGRσRadar Transmit PowerPT Receive Pow er PRD Radar Cross Section σR∗γBWGT GRPTPR   Figure 3.1  Illustration of the principle of Radar.   For better understanding the Rad ar equation will be progressively derived in this section. 
 (ILL     PP n  7 0RATT   $IGITAL )MAGE 0ROCESSING  .EW 9ORK 7ILEY  3ONS    PP n  - 3IMON  * /MURA  2 3CHOLTZ  AND " ,EVITT  h,OW PROBABILITY OF INTERCEPT COMMUNICATIONS v  #HAPTER  IN  3PREAD 3PECTRUM #OMMUNICATIONS (ANDBOOK   .EW 9ORK -C'RAW 
 Thus, the phase-front distortions affect all types of angle-sensing radars. Many measurements of angle noise have been made on a variety of aircraft, and  the results of theoretical studies have been verified. The theory and measurements  show that angle noise expressed in linear units of displacement, such as meters, of the  apparent position of the target from the center of gravity of the target is independent  of range (except for very short ranges). 
         
 1975. pp. 262 267. 
 As before, transmitting  and receiving feeds may be separated. Multiple beams are again possible with addi - tional feeds. The phase shifter must be reciprocal so that there is a net controllable phase shift  after passing through the device in both directions. 
 £È°xä  2!$!2 (!.$"//+  ARE PRESENT  THE TARGET IS SAID TO BE PARTIALLY POLARIZED WHEN NO RANDOM COMPONENT IS  PRESENT  THE TARGET IS FULLY POLARIZED 2ADAR SIGNALS ARE FREQUENTLY ONLY PARTIALLY POLARIZED  ESPECIALLY WHERE MULTIPLE BOUNCES OCCUR WITHIN THE TARGET AREA &OR THE NONRANDOM PART  WE MUST DEFINE A 3TOKES VECTOR USING AN ENSEMBLE AVERAGE  OF EACH COMPONENT THE AVERAGING MAY BE OVER TIME OR LOOK ANGLE 4HUS WE HAVE   & 
 When the radar is jammed, it is of inter - est to calculate the degradation of the detection range with respect to self-screening,  standoff, and escort jammers. These calculations apply to both search and tracking  radars. For tracking radars, it is also worthwhile to consider the degradation of mea - surement accuracy and resolution. 
 1Incertain parts oftheworld, theeffect oftrapping hasbeen observed forfre- quencies aslowas200Me/see.. SEC. 2.14] L7UPERREFRACTION 57 That the height ofthe duct and the wavelength should berelated, and insuch amanner that the heights involved arehundreds oftimes greater than the corresponding wavelengths, may perhaps bemade plausible tothereader acquainted with propagation through waveguides. 
 30. Pilon, R. O., and J. 
 A. Kitaigorodskii,” J. Geophys. 
 BANDWIDTH PRODUCT OF A SIGNAL v  53 0ATENT   .OVEMBER     7 * #APUTI  h0ULSE 
 The transit time is  proportiorial to the difference in freqileticy between the echo signal and the transmitter signal.  The greater the transmitter frequency deviation in a given time interval, the more accurate the  measurement of the transit time and the greater will be the transmitted spectrum.  CWANDFRE<)lJENCY-MODlJI.ATED RADAR HI Scan reference SCR/584 servosystem 1kHz30kHzM Doppler amplifier e--_K_1Y-,sl_ro_n--,1 AFCSignalIF Reference IFX+D --X Pedestal control Figure3.9Blockdiagram oraCWtracking-illuminator.31(Courtesy IEEE.) discrimination ofaCWradarallowsoperation inthepresence ofclutterand·hasbeenwell suitedforlowaltitude missiledefensesystems. 
 SIDED )& BANDWIDTH TO BE LESS THAN THE SAMPLING RATE .OW LETS DERIVE THE DIRECT 
 SCAN CORRELATION !LTH OUGH IT IS EASY FOR MOD 
 Velocity (or doppler) tracking in a pulse doppler radar is carried out by forming a centroid on the target's doppler return in the filter bank. A closed-loop tracker then positions a doppler window around the tracked target such that returns which differ in doppler by more than a predetermined value are discarded by the tracker. In me- dium PRF, the PRF has to be adjusted to keep the doppler return away from the main-beam clutter notch as well as to avoid range eclipse. 
 3!2 MODE  AS WELL AS THE 3!2 ITSELF   o  4HE FIRST DIGITALLY PROCESSED IMAGES FROM THE 3EASAT 3!2 REQUIRED  HOURS FOR A QUARTER 
 Pulse compression waveforms and processing are discussed in Sec. 11.5. Although  pulse compression radar is of interest for other than the extraction of information, it is  included in this chapter because of its close relation to the ambiguity function. 
 REALTIVE DOPPLER SHIFT fT FIG. 15.26c Six-pulse filter that responds to targets at zero doppler but rejects chaff at/T= 0.8. Figure \5.26d shows the composite response of the filter bank. 
 Thediscontinui-  ties. and hence the backscattering, of the cone-sphere are from the tip and from the join  between the cone and the sphere. There is also a backscattering contribution f~om a "creeping  Figure 2.11 Radar cross section of a cone sphere with 15" half angle as a function of the diameter in  wavelengths. 
 TIONAL CAPABILITY SIMILAR TO THE REDUNDANCY COMMONLY EMPLOYED IN &!! AIR 
 The actual matched ﬁlter contains the phase error, which means the range migration of target P cannot be compensated correctly. The actual matched ﬁlter can be expressed as: H(θ,tr)=exp⎭braceleftBigg j⎭parenleftBigg4πfc c·Rp+Δp⎭parenrightBigg⎭bracerightBigg (10) where Δprepresents the phase error: Δp=4πfc c·(Rp0−Rp) (11) where Rp0represents the distance between P 0and the APC, which can be expressed as: Rp0=⎭radicalbigg (ROA−r)2+r2+h2−2r⎭radicalBig (ROA−r)2+h2cosθ (12) ROA=⎭radicalBig R2 0−h2 (13) where ROAis the ground range from the target to the rotation center. Therefore, the imaging result of the target P on the reference plane is Gp0=⎭integraldisplay θSc(θ,tr)·H(θ,tr)dθ=⎭integraldisplay θBrsin c⎭parenleftBig Br⎭parenleftBig tr−2Rp/c⎭parenrightBig⎭parenrightBig exp(jΔp)dθ (14) The matched ﬁlter in Equation (10) cannot correctly compensate for the range migration. 
 16. Richards, C. J .. 
 Since the pulse-doppler radar is capable of good MTI  performance, it is also a good AMTI radar. However, if the antenna sidelobes are not low, the  clutter that ent'irs tlie radar via the sidelobes can limit the improvement factor, as mentioned  previoilsly [Eq. (4.40)]. 
 29. Golay, M. J. 
 135. W. C. 
 Because of its distributed nature,  the measure of the backscattering echo from such clutter is generally given in terms of a  CHAPTER THIRTEEN RADAR CLUTTER .) 13.1INTRODUCTION TORADAR CLUTfER Cluttermaybedefinedasanyunwanted radarecho.Itsnameisdescriptive ofthefactthat suchechoescan"clutter"theradaroutputandmakedifficultthedetection ofwantedtargets. Examples ofunwanted echoes,orclutter,inaradardesigned todetectaircraftincludethe reflections fromland,sea,rain,birds,insects,andchaff.Unwanted echoesmightalsobe obtained fromclear-air turbulence andotheratmospheric effects,aswellasfromionized mediasuchastheauroraandmeteortrails.Clutterisgenerally distributed inspatialextent,in thatitisusuallymuchlargerinphysical sizethantheradarresolution cell.Therearealso "point" clutterechoes,suchastowers,poles,andsimilarobjects.Theechofromasingle birdisalsoanexample ofpointclutter.Whenclutterechoesaresufficiently intenseand extensive, theycanlimitthesensitivity ofaradarreceiver, andthusdetermine therange performance. Insuchcircumstances, theoptimum radarwaveform andreceiverdesigncanbe quitedifferent thanwhenreceivernoisealoneisthedominant effect. 
 It is of little concern at UHF or higher frequen~ies.~~  Solar noise. The sun is a strollg emitter of electromagnetic radiation, the intensity of which  varies with time. The minimum level of solar noise is due to blackbody radiation at a tempera-  ture of about 6000 K.56-57 The solar noise is unlike most other noise mechanisms in that its  power increases with increasing frequency. 
 !Function of the collector voltage level. ^Function of pulse length and transistor geometry. Power lost (dB down) = 10 log [(I + cos 0)/2] (5.1) where 9 is the phase difference between amplifiers. 
 L. Williams, Civil marine radar , London: Institution of Electrical Engineers, 1999,   Sec. 10.3. 
 Since the electron beam is deﬂected from the center of the CRT screen with each pulse of the transmitter, the sweep must be repeated very rapidlyeven when the lower pulse repetition rates are used. With a pulse repetitionrate of 750 pulses per second, the sweep must be repeated 750 times persecond. Thus, it should be quite obvious why the sweep appears as a solidluminous line on the PPI. 
  %#237#23!.403 
 No. 490, Edinburgh, UK,  15-17 October 2002, pp. 424-428. 
 %AST 
 A programmable oscillator, which can correct for first-order doppler effects,  then mixes the IF signal to baseband, and digital samples are stored for later processing. Although an analog- to-digital conversion is shown at the output, the ADC may actually take place at any point in the system.2  (Courtesy SciTech )ANTENNA 1-10 GHz 300 MHz IF LNA NOISE DIODEAMBIENT LOAD FIXED LOCAL OSCILLATORPROGRAMMABLE OSCILLATORADC100 kHzDIGITAL STORAGE ch23.indd   14 12/20/07   2:21:25 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Onemethodofobtaining trackswithasurveillance radaristohaveanoperator manually markwith gr~asepencilonthefaceofthecathode-ray tubethelocation ofthetargetoneach scan.Thesimplicity ofsuchaprocedure isoffsetbythepooraccuracy ofthetrack.The accuracy oftrackcanbeimproved byusingacomputer todetermine thetrajectory from inputssupplied byanoperator. Ahumanoperator, however, cannotupdatetargettracksata rategreaterthanaboutoncepertwoseconds.69Thus,asingleoperator cannothandlemore thanaboutsixtargettrackswhentheradarhasatwelve-second scanrate(5rpmantenna rotation rate).Furthermore anoperator's effectiveness indetecting newtargetsdecreases rapidlyafteraboutahalfhourofoperation. Theradaroperator's traffichandling limitation andtheeffectsoffatiguecanbemitigated byautomating thetargetdetection andtracking processwithdataprocessing calledautomatic detection andtracking (ADT).Theavailability of digitaldataprocessing technology hasmadeADTeconomically feasible. 
    PP n  .OVEMBER   $ + 0 4AN  ( 3UN  9 ,U  - ,ESTURGIE  AND ( , #HAN  h0ASSIVE RADAR USING GLOBAL SYSTEM FOR  MOBILE COMMUNICATION SIGNAL 4HEORY  IMPLEMENTATION AND MEASUREMENTS v  )%% 0ROC 
 For each frequency conversion, spurious higher-order mixer products must be considered and kept out of the target spectrum. As additional conversions are added, this task becomes increasingly difficult and seeker complexity grows. EX-FRONT ANTENNAGIMBAL SERVOANTENNA (HEAD) CONTROLBORESIGHT ERROR TO AUTOPILOT FRONT IFBALANCED MIXERVIDEO (DOPPLER) AMPLIFIERDOPPLER TRACKER (SPEEDGATE) AFCSPEEDGATE LOCAL OSCILLATORAFCLOCAL OSCILLATOR REARIF REAR ANTENNA . 
 Remote Sens. Lett. 2006 ,3, 512–516. 
 Schleher, MTI and Pulsed Doppler Radar , Norwood, MA: Artech House, 1991. 17. N. 
 ,/" Ê7/Ê- 4HE MARITIME !UTOMATIC )DENTIFICATION 3YSTEM !)3  IS A TARGET INFORMATION SYSTEM  THAT PERFORMS SIMILAR FUNCTIONS TO AIRBORNE 3ECONDARY 3URVEILLANCE 2ADAR 332   SUCH AS !IR 4RAFFIC #ONTROL "EACON 3YSTEM !4#2"3  AND )DENTIFICATION &RIEND OR &OE )&&  (OWEVER  THE VAST MAJORITY OF TRANSMISSIONS ARE NOT THE  RESULT OF ANY INTERROGA 
 Thistechnique hasbecncalledwithill-/1lilse scanning. Theheightresolution depends ontheantenna beamwidth. asinaconventional frequency­ scanantenna; buttherangeresolution isdetermined bythefrequency spectral components. 
 24.Merriman, R.H.,andJ.W.Rush:Microwave Doppler Sensors,MicrowQl'e J.,vol.17,pp.27-30.July. 1974. ... 
 ($"+ 
 The latter nor - mally consists of an ultrahigh speed sample and hold circuit. The control signal to the  sample and hold circuit, which determines the instant of sample time, is sequentially  incremented at each pulse repetition interval. For example, a sampling increment of  t = 100 ps is added to the previous pulse repetition sampling interval to enable sam - pling of the received signal at regular intervals as indicated in Figure 21.16. 
 Schenstcd, anti I. V.  Schensted: Bistatic Radar Cross Sections of Surfaces of Revolution. 
  AND %23 
 Figure 23.10 shows the geometry. This problem commonly  arises when attempting to hitchhike off monostatic surveillance radars. Four remedies  are available to mitigate the beam scan-on-scan problem: (1) step scanning, (2) flood - light beams, (3) multiple beams, and (4) time-multiplexed beams, which in the limit  is called pulse chasing . 
 Although a single general-purpose computer can be used to perform  all the computations and control required for a phased-array radar, it is often desirable to  utilize a separate, special-purpose computer for beam steering. This can be an integral part of  the radar hardware so as to minimize the problem of communicating the large number of  phase-shifter orders. The general-purpose radar-control computer provides the beam-steering  computer with the desired elevation angle and azimuth angle. 
 18.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 Space-Based Remote  Sensing Radars R. Keith Raney Johns Hopkins University Applied Physics Laboratory 18.1 PERSPECTIVE Motivation.  Worldwide, the rate of investment in space-based radar (SBR) dur - ing the time the radars in this chapter were operating was on the order of one billion  dollars per year. 
 Space-based SAR systems have motivated fruitful specializations in quantitative  applications in a wide variety of areas, comprehensively reviewed in the  Principles  and Applications of Imaging Radar .5 Topics such as SpotSAR, ScanSAR, polarimetry,  and interferometry that have influenced radar system and mission design are outlined  in closing paragraphs of this section. Flight Systems.  The concept of SAR, introduced in 1951 by Carl Wiley,6 was  reduced to practice in subsequent years, first through simulations, then through air - borne proof-of-concept systems.7 Quill, the first space-based SAR (see Table 18.2),  was launched only a decade later. 
 'ATE $URATION. 
 ! IS AN EXAMPLE  WITH A PEAK POWER OF  K7   DUTY CYCLE  AND  D" GAIN )T OPERATES AT , BAND FROM  TO  -(Z 4HE 53 !IR &ORCE #OBRA $ANE  OPERATING FROM  TO  -(Z  IS A LONG RANGE RADAR LOCATED IN THE !LEUTIAN )SLANDS THAT USES  RING 
 STATE  :OLPER  DRAWS HISTORICAL REFERENCE TO THE FIRST  SECOND  AND THIRD GENERATION OF SEMICONDUC 
 FICIENT TO ACCOMMODATE ANY COMBINATION OF POWER AMPLIFIER FAILURES L 4HE MECHANICAL PACKAGING OF THE POWER COMBINER SHOULD ALLOW MODULES TO BE  REPAIRED EASILY 4HE PACKAGING SHOULD ALSO PROVIDE SHORT  EQUAL PHASE AND LOW 
 25-27, January 1974. 10. Williamson, R. 
 2.9  2.3 Definition and Evaluation of  Range Factor s  ...........  2.10  Transmitter Power and Pulse Length  .................  2.10 Antenna Gain, Efficiency, and Loss Factor  ......... 
 gO.Kurtz.L.A.,andR.S.Elliott:Systematic ErrorsCaused bytheScanning ofAntenna Arrays: Phase Shifters intheBranch Lines,IRETrailS.,vol.AP-4,pp.619-627, October, 1956. 81.Scudder, R.M.,andW.H.Sheppard: AN/SPY-I Phased-Array Antenna, MicrolVal'e J.,vol.17, pr.51-55,May,1974. ~Q.Cheston, T.C,andJ.Frank:ArrayAntennas, chap.IIofRadarHalldbook, M.I.Skolnik (ed.). 
 TRACK DIRECTION PRESENTS EVEN MORE OF A CHALLENGE 4HE SECOND PROBLEM IS RANGE SIDELOBES &ROM ORBITAL ALTITUDES AND FROM A REALISTIC  SPACECRAFT  IT IS NOT FEASIBLE TO TRANSMIT A SIMPLE SHORT PULSE THAT HAS SUFFICIENT ENERGY TO GENERATE USEFUL REFLECTIONS FROM DEPTH ,ONG MODULATED PULSES ARE THE ONLY PRACTICAL METHOD 5NFORTUNATELY  THE SPECULAR COMPONENT OF SURFACE REFLECTION USUALLY IS VERY STRONG AT THE LONG WAVELENGTHS REQUIRED FOR SUBSURFACE SOUNDING 0ULSE COMPRESSION OF THE SURFACE RETURN GENERATES RANGE SIDELOBES WHICH APPEAR AT DEPTHS THAT COULD EASILY OVERWHELM THE WEAKER REFLECTIONS FROM THE INTERNAL STRUCTURE 4HE STANDARD STRATEGY TO MITIGATE THIS PROBLEM IS RIGOROUS SIDELOBE CONTROL  REQUIRING SEVERE PULSE AMPLITUDE WEIGHTING AND STRICT CONTROL OF PHASE AND AMPLITUDE LINEARITY $UE TO THE LARGE FOOTPRINT OF A SPACE 
 ANE-I, no. 2, pp. 3-7, June, 1954. 
 It is necessary for us to use an entirely new type  of valve for oscillations at 3009 megacycles a second, and  . CENTIMETRIC TECHNIQUE 1i7  in these valves the electron stream is caused to excite the  oscillatory circuit by a mechanism which, indeed, makes  use of the finite times of travel of the electrons.  The general name of these generators is ‘hollow-space  oscillators,’ and in this class come the magnetrons, the  klystrons, Heil tubes, and other devices, detailed descrip-  tion of which is in many cases impossible, for, like the  precise details of the harnessing of atomic power, they  are still a part of secret State information. 
 ING TO A DIFFERENT AREA 3OME MILITARY SYSTEMS SUCH AS THE 0ATRIOT WITH THE  o CONE  OF INSTANTANEOUS VIEW IS FIXED ON ITS VEHICLE WITHOUT A PEDESTAL AND IS DEPENDENT ON  MOVEMENT OF ITS VEHICLE TO CHANGE THE REGION OF ANGULAR COVERAGE AS NEEDED 4HE ADVANTAGES OF SPACE FED ARRAYS ARE L #ONVENTIONAL MONOPULSE MICROWAVE HORN FEEDS ARE USED L !RRAY ELEMENTS ARE AVAILABLE  WITH SELECTABLE POLARIZATION OF THE RADIATED ENERGY WHEN  FED BY AN OPTIMIZED LINEAR POLARIZED MONOPULSE FEED SUCH AS IN &IGURE   AND SELECT 
 C. F. Winter. 
 The structure also would have to be stronger.  The effect of ice on the electrical characteristics of a mesh reflecting surface is twofold. 1 ij  On the one hand, ice which fills a part of the space between the mesh conductors may he  considered a dielectric. 
 lOb. Since the effective numbe·r of pulses integrated is equal to  ( I -k)-1, a value or k 0.9 corresponds to about 10 pulses integrated and k = 0.98 to about  50 pulses. However, when the recirculating-delay-line integrator is implemented with digital  circuitry, values of k approaching unity can be achieved.65 ·  The factor k in the recirculating-delay-line integrator of Fig. 
 The output of the feedback loop will be zero unless the feedback voltage exceeds a  prespecified minimum value V, .\In the block diagram the feedback voltage and the voltage  are compared in the d-c amplifier. If the feedback voltage exceeds V,, the AGC is operative,  while if it is less, there is no AGC action. The voltage V, is called the delay ~jolragr. 
 OF 
 A. Brown, P. De Mey, R. 
 An excellent discussion of over 20 weighting functions (not including Taylor) is  given by Harris.32 Signal-To-Noise Ratio (SNR).  For a real radar, for which the exact phase of the  target echo can never be known in advance, the greatest achievable signal-to-noise  ratio (SNR) is (Sullivan,1 Section 4.2.2)  SNR=E kTF0 (17.26)  E P tA=−Rxavg (17.27) where E = collected energy; k = Boltzmann’s constant = 1.38 × 10–23 joule/Kelvin;  T0 = standard temperature (290 K); F = “noise figure,” which is typically about 2;   PRxavg− = average received power; and tA = time to form the synthetic aperture.  (The denominator of Eq. 
 Available online: www.fs121.com/ foreportinfo.aspx?Id =132832 (accessed on 1 December 2016). ©2019 by the authors. Licensee MDPI, Basel, Switzerland. 
 2, April 1996, pp. 668–675. 38. 
 g's of 20,000 to 100,000 are normally employed. The action of the cavity is primarily that of an additional reactive element directly in parallel with the cavity in the klystron. With a high-quality reflex klystron having an FM noise 110 dB below the carrier in a 1-Hz band spaced 10 kHz from the carrier, use of the high-g cavity as a passive stabilizer reduces the corresponding FM noise 130 to 135 dB below the carrier. 
 Figure 4.17. Attenuator type 58, general view of hardware [ 6].Airborne Maritime Surveillance Radar, Volume 1 4-17. Figure 4.19. 
 3.6 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 TACCAR.  The MIT Lincoln Laboratory originally developed TACCAR to solve  the AMTI radar problem. The requirements and thus the implementation of TACCAR  change depending upon the type of clutter cancellation processing employed. 
 , and the largest with rank n − 1. Under the hypothesis that  all the samples are independent samples from an unknown density function, the test  sample has equal probability of taking on any of the n values. For instance, referring to  the ranker in Figure 7.20, the test cell is compared with 15 of its neighbors. 
 Such a phase error, for example,  might be caused by a deformation of the surface from its true value. Ruze'O ' showed in a simple  derivation that the gain of a circular aperture with arbitrary phase error is approxin~atcly  262INTRODUCTION TORADAR SYSTEMS 7.8EFFECT OFERRORS ONRADIATION PATIERNS7J•99101 Antenna-pattern synthesis techniques suchasthosediscussed inSec.7.6permittheantenna designer tocompute theaperture illumination required toachieve aspecified radiation pattern. However, whentheantenna isconstructed, itisusuallyfoundthattheexperimentally measured radiation patterndeviates fromthetheoretical one,especially intheregionofthe sidelobes. 
 Precision Tracking During Rapid Scan.2—.At the end ofSec. 6.12 weconsidered thedesign ofsystems forgeneral airsurveillance and control which offered fairly accurate information, renewed ever,y few seconds, onallthe positional coordinates ofalltargets inthe radar field ofview. This was claimed tobetheoperational ideal; and soitis,fora radar setwhose purpose istopermit thegeneral control ofaircraft. 
 Furthermore, theremustbenoobstructions inthevicinityoftheantenna thatcandivert energytothesidelobe regionsandappearashighsidelobes. Alowsidelobe antenna might havetobe20to30percentlargerthanaconventional antenna toachievethesamebeamwidth. Aperture efficiency. 
 The number of independent samples can be  found from Eq. 16.15 or Eq. 16.16 after suitable analysis. 
 Darlington, and W. J. Albersheim, “The theory and design of chirp  radars,” Bell Syst. 
 RANGE ERROR IS SLIGHTLY REDUCED BUT  THE CROSS 
 !'roe. World Con( 011 Bird Hazards co Aircraft, Canada, pp. 359-376, 1969. 
 Intcrfercricc froni otiicr radars might appear as one large return among the ten returns  normally processed. 111 the MTD, an interference eliminator compares the magnitude of each  of the 10 pi~lses against the average magnitude of the ten. If any pulse is greater than five times  tlie average, all inforination from that range-azimuth cell is discarded. 
 TO 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 17 .26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 In addition to this echo, the pixel containing the target will produce an additional echo  with a periodic phase error :  φπ λπ φ πe odf t f t = =42 2 sin( ) s in( )vib vib (17.42) We assume 4 p  d  l, thus fo  1. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 5.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 For example, the threshold scheme might be 15 dB SNR per PRI and 3 out of 8  for all PRIs. 
 Vertical Scan Only. A greatly simplified phased array system becomes pos- sible if there is no need for multifunction capabilities, including fire control, where a beam may have to be pointed in any given direction at any time. The array is scanned in the vertical plane only and mechanically rotated to give azi- muth coverage. 
 2. S. G. 
 binomial-weight canceler configurations. If the -6 dB response relative to nor- mal response is used as the measuring point, the rejection is 24 percent of all tar- get dopplers for the single canceler, 36 percent for the dual canceler, and 45 per- cent for the triple canceler. Consider the dual canceler, for example. 
 Judson produces several small models, one ofwhich israted 150watts 400 cps and weighs about 15lb. The general design issimilar tothat of the Jacobsen machine, except that the engine isbelt-connected tothe generator. There isnoway ofregulating theoutput voltage ofpermanent-magnet generators, but capacity inseries with the output will hold the output voltage constant toabout i5per cent despite changing load. 
 MINUTE TIME LAPSE OF TRACKS FORMED FROM DATA   IN &IGURE A  USING 'LOBAL .EAREST 
 582 PRIME POWER SUPPLIES FORRADAR [SEC. 14.9 rectifier cathodes may useupa)arge part ofthe50to60watts ofavail- able power. Two ormore vibrator power supplies can bedesigned foroperation in series orinparallel onthe d-c output side, sothat larger currents or voltages can beobtained from small vibrators. 
 SION OF %7 INVOLVING ACTIONS TAKEN TO PREVENT OR REDUCE A RADARS EFFECTIVE USE OF THE %- SPECTRUM %##- COMPRISES THOSE RADAR ACTIONS TAKEN TO ENSURE EFFECTIVE USE OF THE %- SPECTRUM DESPITE THE ENEMYS USE OF %7 4HE TOPIC OF %7 IS EXTREMELY RICH IN TERMS  SOME OF WHICH ARE ALSO IN GENERAL USE  IN OTHER ELECTRONIC FIELDS ! COMPLETE GLOSSARY OF TERMS IN USE IN THE %#- AND %##- FIELDS IS FOUND IN THE LITERATURE    Ó{°ÎÊ 
 The Performance ofRadar.-In discussing the performance of radar, one usually refers toitsrange pwforrnunce-that is,themaximum distance atwhich some target ofinterest will return asufficiently strong signal tobedetected. The factors that determine range performance are numerous and they interact inarather complicated way. Chapter 2is devoted toadiscussion ofthem, and Chap. 
 As part of that analysis, the waveforms of signals at a number of points in the radar system have been described. It is the purpose of this subsection to discuss a number of aspects of signal processing that are common to all mechanizations. Many fine-resolution radar systems employ both pulse compression and syn- thetic antenna generation. 
 STATE TRANSISTOR AMPLIFIER WILL BE THE CHOICE , 
 Table 7.4 summarizes the methods for tuning the Kalman filter. ch07.indd   30 12/17/07   2:14:16 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 SCAN RADAR WITH ESSENTIALLY THE SAME PERFORMANCE AS A CONICAL 
 Three-dimensional near-ﬁeld MIMO array imaging using range migration techniques. IEEE T rans. Image Process. 
 In general, the extremely low sidelobe antenna can be a  better solution, if the desired low sidelobe levels can be achieved and maintained economically.  In principle, the automatic tracking radar discussed in Chap. 5 is another example of an  adaptive antenna. 
 J. Alter: Automatic Detection and  Integrated Tracking System, Record of the IEEE 1975 International Radar Conference, pp. 391-395,  IEEE Publication 75 CHO 938-1 AES. 
 The latter measures the total path length from radar to target to receiver just as does the  bistatic radar. Since the two parts of the path are equal, the distance to the target is one-half  the total path length. The distance or range measurement in the monostatic radar locates tlic  target on the surface of a sphere. 
 Ê 
 Theweightofthemagnetic focusing systemisamajor portionofthetotalweightofaklystron. Thisweightcanrestricttheutilityofklystrons for airborne andportable applications. Klystrons cansometimes befocusedwithlightweight permanent magnets.l.8Permanent magnets requirenopowerinputorcooling, andthevariousprotective circuitsneededwith solenoids areeliminated. 
 14.3AIR-SURVEILLANCE RADAR2729,4649.103 Thefirstsuccessful application ofradarwasforthedetection andtracking ofaircraft. Air surveillance continues tobeoneofthemoreimportant radarapplications forbothcivilian (airtrafficcontrol) andmilitary purposes. Themilitary employsuchradarsforgeneralsurveil­ lanceoftheairspace, forproviding acquisition information toanti-air-warfare systems, andfor directing aircrafttoaninterception. 
 CHANNEL INTERFERENCE FOR /4( RADAR REFERS MAINLY TO OTHER TRANSMISSIONS IN THE (& SPECTRUM THAT EITHER FULLY OR  PARTIALLY OVERLAP THE RADAR BANDWIDTH e  4HE MAIN BEAM AND SIDELOBE CLUTTER RECEIVED BY AIRBORNE RADARS CAN HAVE QUITE DIFFERENT DOPPLER SHIFTS DUE TO  THE MOVEMENT OF THE PLATFORM WITH RESPECT TO THE GROUND RESULTING IN THE ANGLE 
 SCAN BASIS %ACH APPROACH HAS ADVANTAGES 4HE ADVANTAGES OF THE SCAN 
 Figure 11. Low pass (LP)-deformation of the two feature points, derived from a polynomial model: (a) CT1 and ( b) CT2 (with reference to 17 June 2014). 5.4. 
 S. Reed, “A brief history of adaptive arrays,” Subdury/Wayland Lecture Series , Raytheon   Div. Education, notes 23, October 1985. 
 The Gunn and LSA bulk-eflect diodes and the Trapatt and  Impatt a~wlnr~che diodes can be operated as oscillators or single-port negative-resistance  ar~i~lifiers.~~.~~ They liave been considered for use at the higher microwave frequencies where  the transistor amplifier has reduced capability, but they can also operate at L band or below.  Unfortunately, the peak and average powers of such devices are low, as is the efficiency and the  gain. An S-band Trapatt amplifier, for example, might have a peak power of 150 W, 1 ps pulse  width, 100 Hz pulse repetition frequency, 20 percent efficiency, 9 dB gain, and a 1 dB band-  width of 6.25 ~ercent.~~.~~ LSA diodes may be capable of somewhat greater peak power, but  their average power and efficiency are low. 
 PULSE CANCELER AFTER 4 - (ALL AND 7 7 3HRADER Ú )%%%  AND  ( 2 7ARD AND 7 7 3HRADER Ú )%%%   &)'52%  -EAN IMPROVEMENT FACTOR RESTRICTION VERSUS AMOUNT OF LIMITING AND CLUTTER  SPECTRAL SPREAD FOR A THREE 
 If this clutter sequence were 40 dB stronger and passed through a 10 V IF limiter,  only the phase information would remain. Each pulse would have a 10 V amplitude.  When the resulting limited clutter sequence is passed through a three-pulse canceler  (coefficients 1, –2, 1), the output residue appears as in Figure 2.69 a. 
 Tech. Mem. 588. 
 A cornplex target such as an aircraft or a ship may be considered as a  nuniber of independent scattering elements. The echo signal can be represented as the vector  addition of the contributions from the individual scatterers. If the target aspect changes with  respect to the radar-as might occur because of motion of the target, or turbulence in the case  of aircraft targets-the relative phase and amplitude relationships of the contributions from  the individual scatterers also change. 
 The pulse-compression radar,  although widely used as a substitute for a short-pulse radar, has some limitations of its own,  as will be discussed later in this section. 422 INTRODUCTION TO RADAR SYSTEMS  There are at least two ways of describing the concept of a pulse-compression radar. One is  based on an approach similar to that of the ambiguity function of Sec. 
 The clutter echo from a single ground patch has a doppler frequency that  depends on the angle between the clutter patch and the platform flight direction; clutter  from all angles lies on a diagonal ridge across the space-time frequency plane. A main- beam target competes with both main-beam and sidelobe clutter as well as jamming.   ch24.indd   21 12/19/07   6:00:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 L.=“squirted inductance” arising from nonuniform current dis- tribution due tothecharging ofCm Current charging CDmust HOW through L.. Cc=effect ofelectrostatic energy stored between primary and core. Lc=effect ofmagnetic energy stored in“squirted flux” which comes from nonuniform current inprimary coil arising from the charging ofCc. 
 476–481, February 1958. 17. C. 
 At frequencies above Ka band most microwave techniques are inadequate,  so that new technology is required. Thus Ka band should not usually be included as part of  the millimeter-wave region.  Advantages of millimeter waves. 
 BEAM TECHNIQUE REDUCES THE RETURNS FROM VERY LOW ELEVA 
 704 RADAR RELAY @EC. 17.7 illustrates such amethod. The stators ofthescanner synchro areexcited byequal-amplitude signals offrequencies f,and f,,asarethetwo equal primaries ofatransformer whose secondary isinseries with the synchro rotor. 
 Powell, “Terrain Integrated Rough Earth Model (TIREM),” Rep. TN-83-002, Electromagnetic  Compatibility Analysis Center, Annapolis, MD, September 1983.  9. 
 As a complex image, the SAR image contains amplitude and phase information. We can get the deformation of the scenes by di ﬀerential interferometric SAR (D-InSAR). Therefore, SAR is widely used in the ﬁeld of ground deformation monitoring [ 3–5]. 
 S.: The Theory of Antenna Arrays, " Microwave Scanning Antennas, vol. [I," R. C. 
 Zrnic ′85 gives the more  general following expression for the variance of the mean frequency estimate f for the  pulse-pair estimation technique and a gaussian-shaped spectrum  var(ˆ)( )(/fT T TTN SN STf = + + −1 82 21 22 023 22 2π ρπ σ ρ ) ) [ ]     (19.46) where r is the correlation coefficient and N/S is the noise-to-signal ratio. Equation  19.46 applies a single PRF with interpulse period T and assumes that all pulses in the  interval T0 are used in the estimation algorithm. It reduces exactly to Eq. 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°£Ç FOR  PULSES INTEGRATED AND  D" FOR  PULSES INTEGRATED !N IMPLEMENTATION  OF THE LOG #&!2 IS SHOWN IN &IGURE  )N MANY SYSTEMS  THE ANTILOG SHOWN IN  &IGURE  IS NOT TAKEN 4O MAINTAIN THE SAME #&!2 LOSS AS FOR LINEAR VIDEO  THE  NUMBER OF REFERENCE CELLS -LOG FOR THE LOG #&!2 SHOULD EQUAL   -LOG   -LIN  
 Different ways of oper- ation refer to the change of the transmitted frequency in frequency-agility or frequency-diversity modes or to the use of wide instantaneous bandwidth.61"64 Frequency agility usually refers to the radar's ability to change the transmitter frequency on a pulse-to-pulse or batch-to-batch basis. The batch-to-batch ap- proach allows doppler processing, which is not compatible with frequency agility on a pulse-to-pulse basis. In a waveform with pulse-to-pulse frequency agility, the center frequency of each transmitted pulse is moved, in either a random or a programmed schedule, between a large number of center frequencies on a pulse- to-pulse basis. 
 LIMINARY AND USEFUL INDICATION OF PERFORMANCE UNDER %#- THREAT AND %##- DESIGN EFFECTIVENESS THAT PRODUCES BASELINE VALUES PRIOR TO SIMULATION AND OPERATIONAL TESTS ! CLASSICAL BOOK PRESENTS ACCURATE DETECTION RANGE EQUATIONS IN A VARIETY OF PRACTICAL SITUATIONS  )N THE SECOND PART OF THIS SECTION  A REVIEW OF SOFTWARE TOOLS AVAILABLE FOR  THE PREDICTION OF RANGE EQUATION IN JAMMING AND CHAFF CONDITIONS IS GIVEN /F COURSE  THE RADAR EQUATION IS A SIMPLIFICATION IN ASSESSING  %#- 
 RELATED AIRCRAFT ACCIDENTS v  "ULL !M  -ETEOROL 3OC  VOL   PP n    4 &UJITA  h4HE DOWNBURST v 3ATELLITE AND -ESOMETEOROLOGY 2ESEARCH 0ROJECT  $EPARTMENT OF THE  'EOPHYSICAL 3CIENCES  5NIVERSITY OF #HICAGO    4 &UJITA  h4HE $&7 MICROBURST v 3ATELLITE AND -ETEOROLOGY 2ESEARCH 0ROJECT  $EPARTMENT OF  THE 'EOPHYSICAL 3CIENCES  5NIVERSITY OF #HICAGO  . 
 111. Leichter, M.: Beam Pointing Errors of Long Line Sources. Hughes Aircraft Co. 
 73-78, January, 1970.  33. Nathansdn, F. 
 WINDOW DETECTOR FOR BINARY INTEGRATION v  )%%% 4RANS  VOL )4 
 TRACKING PERFORMANCE &ORTUNATELY  MOST ARE INSIGNIFICANT EXCEPT FOR VERY HIGH 
 345-348. 37. Rhodes, D. 
 163, January, 1970.  36. Holl. 
 D., M. Perry, and D. H. 
 To produce an ambiguity diagram such as that shown in  Fig. 11.8, the transmissions must be noiselike.  The synthesis of the waveform required to satisfy the requirements of accuracy, ambigu­ ity, and resolution as determined by the ambiguity diagram is a difficult task. 
     PP n  *UNE   $ + "ARTON   -ODERN 2ADAR 3YSTEM !NALYSIS AND -ODELING   #ANTON  -! !RTECH (OUSE )NC     #HAP   P    & % .ATHANSON  * 0 2EILLY  AND - . #OHEN   2ADAR $ESIGN 0RINCIPLES 3IGNAL 0ROCESSING AND  THE %NVIRONMENT  ND %D .EW 9ORK -C'RAW 
 TO 
 Ciiriztori: Reflectiori (.'oefiicients of Irregular Terrain at 10 Cln, Proc.. IR1:'.  vol. 
 If there exists,  however, inherent instabilities in the radar system there can result noiselike time-sidelobes . EXTRACTION OF INFORMATION AND WAVEFORM DESIGN 433  accompanying the pulse"'compression wavefoFm, Such system.instabilities might be .caused by  noise on local oscillators, noise on transmitter power supplies, transmitter time jitter, and  transmitter tube noise. These noise sidelobes will not cancel in the MTI system and, if  sufficiently large, they can result in uncancelled residue that will appear on the radar display. 
 Practically, this isnot always possible, because ofclutter fluctuations, the finite perfection ofcancellation, etc. Under these circumstances, it appears desirable toadjust theresidual clutter, after cancellation, sothat itresembles receiver noise inamplitude and texture when itispresented onthe scope. Clutter fluctuations already have anamplitude distribution like that ofnoise, whether they aredue toscanning ortotheaction ofthewind. 
 TO 
 Zahm, C. L.: Application of Adaptive Arrays to Suppress Strong Jammers in the Presence of Weak  Signals, IEEE Trans., vol. AES-9, pp. 
 SCALE LEVEL 3IMILAR TO )-$ FOR AMPLIFIERS  THE MOST SIGNIFICANT DISTORTION IS USUALLY SECOND ORDER OR THIRD ORDER )-$ PRODUCTS (OWEVER  DUE TO THE COMPLEX NATURE OF THE DISTORTION MECHANISM IN !$ CONVERTERS  THE AMPLITUDE OF )-$ PRODUCTS IS NOT EASILY CHARACTERIZED AND PREDICTED BY THE MEASUREMENT OF AN INPUT INTERCEPT POINT )NPUT .OISE ,EVEL AND $YNAMIC 2ANGE  !CCURATE SETTING OF THE !$ CON 
 This implies that the  rriiriir~iuni rrrls range error for a perfectly rectangular pulse is zero and that the range measure-  nient can be made with no error. In practice, however, pulses are not perfectly rectangular  since a zero rise time or a zero fall time requires an infinite bandwidth. Finite bandwidths  result in finite rise times and finite D2. 
 MINED BY WHAT THE RADAR IS REQUIRED TO DO /THERS MAY BE DECIDED UPON UNILATERALLY BY THE CUSTOMERBUT THAT SHOULD BE DONE WITH CAUTION 4HE CUSTOMER USUALLY SHOULD BE THE ONE WHO STATES THE NATURE OF THE RADAR TARGET  THE ENVIRONMENT IN WHICH THE RADAR IS TO OPERATE  RESTRICTIONS ON SIZE AND WEIGHT  THE USE TO WHICH THE RADAR INFORMATION IS TO BE PUT  AND ANY OTHER CONSTRAINTS THAT HAVE TO BE IMPOSED &ROM THIS INFORMATION  THE RADAR SYSTEMS ENGINEER DETERMINES WHAT IS THE RADAR CROSS SECTION OF THE TARGET  THE RANGE AND ANGLE ACCURACIES NEEDED TO MEET THE RADAR USERS NEEDS  AS WELL AS THE ANTENNA REVISIT TIME 3OME PARAMETERS  SUCH AS ANTENNA GAIN  MIGHT BE AFFECTED BY MORE THAN ONE NEED OR REQUIREMENT &OR INSTANCE  A PARTICULAR ANTENNA BEAMWIDTH MIGHT BE INFLUENCED BY  THE TRACKING ACCURACY   RESOLUTION OF NEARBY TARGETS  THE MAXI 
 J.: "Radar Observation of the Atmosphere," Unit). of Chicugo Press, Chicago, Ill., 1973.  71. 
 E., 29  KIPP RELAY, 93  Kiystron, I17, E19 ef seg.  LAGGING EDGE, 39  Lander, Harold, 26  Leading edge, 39  r'73  . 174 Lewis, Dr W. 
 Soc. Am., vol. 44, pp. 
 If the stable clocks are slaved to a second source, estimated timing accuracies of 0.5 |ms for loran-C and <0.1 jxs for Navstar GPS are reported.82 Phase Synchronization and Stability. As with monostatic radars, doppler or MTI processing can be used by the bistatic receiver to reject clutter or chaff. If noncoherent MTI is acceptable for clutter rejection, the bistatic receiver can use a clutter reference, exactly as a monostatic radar would, given that clutter patches are illuminated by the transmitter. 
 Inthissection, theradarmaybethought ofascarriedbyan aircraft. butsimilararguments applyforsatellites orothermoving vehicles. Figure14.1showsanaircrafttraveling withaconstant velocityvalongastraight path.Its radarantenna ismounted soastoradiateinthedirection perpendicular tothedirection of motion. 
 This is just what has been observed.51 It should be remarked,  however, that shadowing  at low grazing angles is a complex phenomenon (see below),  and the physical origin or even the existence of a critical angle is still open to ques - tion. Moreover, there is relatively little good data on very low-angle clutter for other  than X-band frequencies, so the general behavior of sea clutter in this angular regime  remains uncertain. ch15.indd   18 12/15/07   6:17:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 This “perfectly rough” assumption was soon found wanting, although it is a  fair approximation for the return from many vegetated surfaces over the midrange of  angles of incidence. Clapp18 described three models involving assemblies of spheres, with different  spacings and either with or without a reflecting ground plane. These models yield  variations from s 0 independent of angle through s 0 ∝ cos q  to s 0 ∝ cos2 q. 
 SIDED SIGNAL BANDWIDTH  "   THE BANDWIDTH CONSIDERING COMPONENTS AT BOTH POSITIVE AND NEGATIVE FREQUENCIES 3AMPLING BELOW THE .YQUIST RATE ALWAYS RESULTS IN ALIASING  BUT SAMPLING ABOVE IT DOES NOT GUARANTEE ALIAS 
 Theoretical predictions in the end-on  region closely match the measured pattern for this particular body . A metal plate is a more elementary structure than the ogive shown in Figure 14.6,  but its RCS pattern is no less complex. Sample patterns are reproduced in Figure 14.7  for four different incident and received polarization combinations. 
 The phase stability of the STC attenuator is also an impor - tant consideration as excessive phase variation as a function of attenuation can have a  dramatic impact on range sidelobes. Clutter Map Automatic Gain Control.  In some radars, mountain or urban clut - ter can create returns that would exceed the dynamic range of the receiver. 
 R-274,  March, 1954.  6. Kretschmer, F. 
 White, W. D.: Pattern Limitations in Multiple-Beam Antennas, I RE Trall\., vol. AP-10, pp. 
 In the example of Fig. 11.20, the output of the 6th and 7th stage are  combined. In modulo-two addition, the output is zero when the inputs are alike [(O, 0) or ( l, 1 )]  and is one when the inputs are different. 
 Waters: The Estimation of Tropospheric Electrical Path  Length by Microwave Radiometry, Proc. IEEE, vol. 58, pp. 
 If the designer has some flexibility in either  the IF center frequency or ADC sample rate, a simplified DDC architecture, direct  digital downconversion, can be considered.4,5 If the ADC sample rate is four times  the center of the IF band, then the sampling process can also shift the spectrum  to baseband, and the NCO and associated multipliers of the general DDC are not  needed. In general, direct conversion to baseband is a simple and cost-effective  DDC method that can be used when the signal being sampled is always centered at  a single frequency. The standard DDC architecture might need to be used when the  center frequency of the signal being sampled dynamically changes, which forces the  DDC’s LO to change accordingly. 
 CIES IS THAT THE OSCILLATOR SPECTRAL DENSITY IS MORE NEARLY CONSTANT AND THE AVERAGE OVER ONE PERIOD OF THE -4) RESPONSE IS UNITY &OR OTHER BINOMIAL COEFFICIENT -4) CANCELERS  THE BREAK FREQUENCIES FOR THE START OF THE RESPONSE FALLOFF ARE  F 4    FOR ONE DELAY    FOR TWO DELAYS   FOR THREE DELAYS  AND  FOR FOUR DELAYS &OR EXAMPLE  CONSIDER AN OSCILLATOR WITH SINGLE 
 SURFACE VECTOR WINDS BY 3TOKES PARAMETER ANALYSIS OF THE MICROWAVE EMISSIVITY FROM THE OCEAN SURFACE   7IND3AT IS ONE OF TWO INSTRUMENTS ABOARD THE  #ORIOLIS SATEL 
 'UIDE  -ODE  4HEORY  OF  7AVE  0ROPAGATION  )NGLEWOOD #LIFFS    .* 0RENTICE 
 Scharroo and P. Visser, “Precise orbit determination and gravity field improvement for the ERS  satellites,” J. of Geophysical Research , vol. 
 TERN CONSISTS OF SIDELOBES  WHICH RESULT IN SIDELOBE CLUTTER 4HIS CLUTTER IS GENERALLY MUCH SMALLER THAN THE MAIN 
 Any difference in  the relative phase between the direct and the reflected waves can be attributed to the difference  in the path length and the change in phase that occurs on reflection. The reflection coefficient  of the surface may be considered as a complex quantity r = peM. The real part p describes the  change in amplitude, while the argument $ describes the phase shift on reflection. 
 OF 
 Then from Eq. (16) wehave v,=206mph. For astorm cloud traveling radially at30mph, the ratio inEq. 
 This is the standard DPCA case. The performance holds to 1.5 wavelengths per interpulse-period platform motion, then decreases slightly, and drops off sharply above 3.5 wavelengths per interpulse period. The shaded region is where the improvement factor varies within the limits. 
 One RSP steps across the even-numbered beams, and the other RSP steps across the odd-numbered beams, so that returns in beam pairs are processed simultaneously: (1,2), (2,3), (3,4), etc. This leapfrog sequence is required to capture all returns in the common-beam area. A second concept uses two beams and two RSPs step-scanning over the vol- ume covered by the n-beam antenna. 
 STATE TRANSMITTER IS USED 4HE RECEIVED SIGNALS ARE AMPLIFIED IN A LOW 
 II.:" Man and Radar Displays," Macmillan Company, New York, 1962.  :m Luxenberg. II. 
 H.: The Fast Fourier Transform and the Butler Matrix. I EEE Trat~s.. vol. 
 Observations with SIR-B indicated that this lack of angular variation of cr° also is present at 1.25 GHz, but lack of calibration prohibited learning the level of scatter at this frequency. TABLE 12.2 Constants for Linear Scattering Model (Summer)* * After Moore, Soofi, and Purduski.82Eq. 12.24« 12.246Polarization V V V H H H V and// V and H V and// V and// V and// V and HAngular range,0 20-60 20-50 20-70 20-60 20-50 20-70 O O O 10 10 10Frequency range, GHz 1-6 (1975) 1-6 (1976) 6-17 1-6 (1975) 1-6 (1976) 6-17 1-6 (1975) 1-6 (1976) 6-17 1-6 (1975) 1-6 (1976) 6-17Constant A or M, dB -14.3 -4.0 -9.5 -15.0 -1.4 -9.1 7.6 6.4 0.9 -9.1 -3.6 -6.5Angle slope B or N, dB -0.16 -0.35 -0.13 -0.21 -0.36 -0.12Frequency slope C, dB/GHz 1.12 -0.60 0.32 1.24 -1.03 0.25 -1.03 -0.73 0.10 0.51 -0.41 0.07Slope cor- rection D, dB/ (° • GHz) 0.0051 0.036 0.015 0.040 . 
 (13.15) to account for the fact that the  effective volume or uniform rain illuminated by the two-way radar antenna pattern is less than  that indicated when the half-power beamwidths are used to define the volume. Assuming a  gaussian-shaped antenna pattern, the volume given by Eq. (13.15) must be reduced by a factor  of 2 In 2 to describe the equivalent volume that accounts for the echo power received by the  two-way antenna pattern from distributed clutter.69 Thus the radar equation of Eq. 
 Mark: Design of a Volumetric Frequency Scanning Antenna, Proceedings  Elrrop~arr Microwar%e Conference, Sept. 8- 12, 1969, IEE Conference Publication No. 58, pp. 
 Greenwood: A Within-Pulse Scanning Height-Finder, lnternatiottal Cor~fer-  er1c.e on Rotlor-- Pre~ettt ancl Fltt~~re, IEE Conference Publication, no. 105, pp. 50-55, 1973. 
 .I. Basic  T·.111/n/. vol, 82. 
 9.17); orbyspinning the. SEC. 9.10] R-F TRAA’SMISS1O.V LIVES 283 paraboloid about anaxis passing through thefeed, theparaboloid being a fewdegrees “drunk” inrelation tothis axis (A>-/APG-15); orbyspinning anelectrically asymmetrical feed about the axis ofthe fixed paraboloid (SCR-584, Fig. 
 Itisimportant, therefore, that the nonlinear element beasefficient aspossible, and that aminimum amount ofadded noise beintroduced. The most satisfactory device that has been found isthe rectifying contact between ametallic point and acrystal ofsilicon.’ For protection and stability thesilicon and the “cat whisker” aresealed upinacartridge. The term “crystal” ordi- narily refers tothe whole assembly, across-section view ofwhich is shown inFig. 
 1.4. Some  or the nomenclature employed to designate the various frequency regions is also shown.  Early in the development of radar. 
 ( d)α=0.0272, Γ0/υ=12π,Vmax=1 m/s, and the current ﬁeld is clockwise. T able 1. The simulation parameters in Figure 2. 
 Generally, the implementation of the chirp pulse­ compression has been less complex than that of the phase-coded pulse.  Although definite differences exist between these two basic waveforms, it would be  difficult to provide precise guidelines describing where one is preferred to the other. Each  apt>lication must he examined individually to determine the best form of pulse compression to  use. 
 called a rotodome. They have been used in ground-based systems as well as in airborne  aircraft-surveillance radars such as the 24-ft-diamctcr radome in the U.S. Navy's E-2C  (Fig. 
 Res ., vol. 107, no. C9, p. 
 8, pp. 827 - 844, Aug. 1991 . 
 Kay, A. F.: Electrical Design of hlletal Space Frame Radomes, IEEE Trans., vol. AP-13, pp. 
 BANDWIDTH PRODUCTS  SPURIOUS SIGNALS ARE LESS CRITICAL AS THEY ARE EFFECTIVELY REJECTED IN THE PULSE COMPRESSION PRO 
 4.3f. The moving targets produce, with time, a  "butterfly" effect on the A-scope.  Although the butterfly effect is suitable for recognizing moving targets on an A-scope, it is  not appropriate for display on the PPL One method commonly employed to extract doppler  information in a form suitable for display on the PPI scope is with a delay-line canceler  (Fig. 
 Harmonics are generated by any component that becomes nonlinear when sub - jected to the power level created by the transmitter and that passes those harmonics to  the antenna. Gaseous or diode receiver-protectors are designed to be nonlinear during  the transmitted pulse and reflect the incident energy back toward the antenna. Isolators  or circulators are often employed to absorb most of the reflected fundamental, but they  are generally much less effective at the harmonics. 
 Automatic- frequency-control Circuit.-The AFC subunit provides automatic control ofthe radar and beacon local-oscillator frequencies. The schematic view oftheeight-tube circuit isshown inFig. 12.21. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 11.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 In the corporate-combined solid-state bottle, high power levels are generated at a  single point by combining the outputs of many power amplifier modules. 
 The airframe aerody- namic response will vary with missile speed and altitude, and the autopilot must compensate for this variation. The final value of ig is a compromise between the rapid desired speed of response to counter target maneuvers and a long desired smoothing time to minimize glint. Moreover, the variations in TS brought about by parasitic feedback effects, such as radome aberration and imperfect antenna stabilization, must be controlled to avoid guidance loop instability. 
 Hydrometeorol. , vol. 4, pp. 
 Theloaded-line phaseshifter,Fig.8.8,consists ofatransmission lineperiodically loaded withspaced.switched impedances, orsusceptances. Diodesareusedtoswitchbetween thetwo stalesofsusceptance. Thespacing between diodesisapproximately one-quarter wavelength at theoperating frequency. 
 299-330, March, 1973.  8. Lien, E. 
 AGE BECAUSE THE FEED IS WITHIN THE &/6 OF THE REFLECTOR ! CONSEQUENCE OF BLOCKAGE IS HIGHER SIDELOBES  THE LEVELS OF WHICH DEPEND UPON THE BLOCKAGE AREA !NOTHER CON 
 COMPRESSION SIDELOBES )F THE PULSE 
 Uncertainty relation. Theso-called" uncertainty" relation ofradarstatesthattheproduct of theeffective bandwidth fJoccupied byasignalwaveform andtheeffective timeduration amust begreaterthanorequalton;thatis,4 ;pa~n (11.34) Equation (11.34),theradar"uncertainty" relationship, maybederivedfromthedefinitions of fJandIXgivenbyEqs.(11.16)and(11.28)andbyapplying theSchwartz inequality. Itisa consequence oftheFourier-transform relationship between atimewaveform anditsspectrum andmaybederivedwithout recourse tonoiseconsiderations. 
 '(Z  TRACKING RADAR THAT IS TRACKING AN AIRCRAFT TARGET WITH A BEACON AT  
 DERIVED DATA  ADDING TO THE INTEGRITY OF THE PRESENCE  POSITION  AND VELOCITY OF TARGETS AND ALSO GIVING INCREASED TARGET INFORMATION )N PRINCIPLE  A CONVENTIONAL SECONDARY RADAR SOLUTION COULD HAVE BEEN ADOPTED BUT INTERNATIONAL CONSENSUS FAVORED THE 3/4$-! APPROACH  AS IT WAS  CAPABLE OF PROVID 
 7.3). COORDINATION WITH THE SCANNER Under various circumstances several different sorts ofelectrical information must bedelivered from thescanner totheindicator. (Some ofthese have already been illustrated inSec. 
 Vander Schurr and P. G. Tomlinson, “Bistatic clutter analysis,” Decision-Sciences  Applications, Inc., RADC-TR-79-70, April 1979. 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°££ ANGLES MORE ACCURATELY THAN THE BINARY INTEGRATOR &OR INSTANCE  IF THERE WERE  PULSES  ON TARGET  ONE COULD BATCH  PULSES  QUANTIZE THIS RESULT TO A  OR A   AND DECLARE A TARGET WITH A  
 Palamutcuoglu, O., J. G. Gardiner, and D. 
 Protection mustbeprovided againstoverload orsaturation. andburnout fromnearbyinterfering tr~nsmitters. Timingand. 
 (From  Gunn and East,71 Quart. J. Roy. 
 Data were downlinked each orbit ( ∼9 MBytes)  and then processed in ground-based facilities. Each imaging pass generated 3200 radar  images that were combined into a survey strip of 120 km wide by 7500 km long. These  were subsequently combined into mosaics. 
 50–52, September 5, 2005. 12. Image Courtesy Raytheon Company, cleared for public release, 265-SPR127.05. 
 KM WIDE SWATH 4HE #/3-/ BUS IS BASED ON THE DESIGN BUILT AND FLIGHT 
 W. Stimson, Introduction to Airborne Radar , 2nd Ed., Mendham, NJ: SciTech, 1998.  6. 
 11. Cochrane, J. B., and F. 
 CESSED THROUGH DOPPLER FILTERING COHERENT INTEGRATION  PRIOR TO DETECTION PROCESSING 7ARD  DESCRIBES THE POSSIBLE 34!0 ARCHITECTURES IN THE CONTEXT OF A GENERALIZED  TRANSFORMATION MATRIX FOLLOWED BY THE ASSOCIATED 34!0 PROCESSING 4HE FOUR CATEGORIES OF 34!0 ARCHITECTURES ARE ORGANIZED IN &IGURE  4HE TRADES FOR AN APPROPRIATE 34!0 DESIGN SOLUTION MUST BE MADE IN THE CONTEXT OF THE TYPE AND SIZE OF THE ANTENNA APERTURE UNDER CONSIDERATION  THE WAVEFORMS UNDER CONSIDERATIONPARTICULARLY THE NUMBER OF PULSES PER #0)AND MOST IMPORTANTLY  THE INTERFERENCE TO BE CANCELLED CLUTTER AND JAM 
 NOISE RATIO OF THE WAVEFORM GENERATOR &OR EXAMPLE  NOISE SPECTRAL DENSITY AT  (Z FROM A CARRIER MAY NEED TO BE AS LOW AS n D"C IN ORDER TO DETECT SOME TARGETS OF INTEREST &OR DESIGNS EMPLOYING AN AMPLIFIER FOR EACH . Óä°Ó{  2!$!2 (!.$"//+  ANTENNA ELEMENT  THE RADIATED PHASE  NOISE WILL GENERALLY ADD NO NCOHERENTLY AND THUS  BE SUPPRESSED BY ^ D" RELATIVE TO BEAMFORMED NOISE POWER FOR A  
 TANCES 0RECISE RANGE MEASUREMENTS ARE MADE WITH THE USE OF A  VARIABLE RANGE MARKER  62-  !T LEAST TWO 62-S ARE NEEDED  EACH WITH NUMERICAL READOUT IN THE DATA AREA OF THE DISPLAY !N ACCURACY OF  IS REQUIRED BUT NOT BETTER THAN  METERS  ! BEARING SCALE AROUND THE PERIPHERY OF THE OPERATIONAL DISPLAY MUST BE VISIBLE 4HIS SCALE CAN HELP USERS DETERMINE THE SHIPS DIRECTION FROM VIEWING THE  HEADING LINE (,   WHICH  HAS TO BE SHOWN ON THE DISPLAY ONLY TEMPORARY EXTINGUISHING OF THE (, IS PERMITTED )N ADDITION  A SHIPS HEADING IS NORMALLY AVAILABLE WITHIN A DATA BOX OUTSIDE OF THE OPERATIONAL AREA 4HE RADAR ORIGIN CAN BE OFFSET FROM THE CENTER OF THE OPERATIONAL AREA BY THE USER THE BEARING SCALE ADJUSTS ACCORDINGLY 4WO OR MORE  ELECTRONIC BEARING LINES  %",S  HAVE TO BE PROVIDED WITH CONTINUOUS  NUMERICAL READOUT !LTHOUGH THESE ARE NORMALLY CENTERED ON THE SHIP AT THE ##20   THEY CAN ALSO BE OFFSET TO ANY POSITION 2EADOUTS RELATIVE TO OWN SHIPS HEADING OR TRUE NORTH CAN BE SET 4HE %", ORIGIN CAN ALSO BE SET SUCH THAT IT FOLLOWS OWN 
 Jones and P. Brown, “Sporadic meteor radiant distributions: orbital survey results,” Mon. Not. 
 21. Pfister, G.: The Series 320 Radar, Three Dimensional Air Surveillance Radar for the 1980's, IEEE Trans., vol. AES-16, pp. 
 STATE DEVICES IS QUITE LIMITED COMPARED TO TYPICAL RADAR REQUIREMENTS .EVERTHELESS  TRANSMITTER DESIGNERS HAVE LEARNED THAT THE REQUIRED HIGHER POWER LEVELS FOR RADAR TRANSMITTERS CAN BE ACHIEVED WITH A SOLID 
 ANTENNA SUM 
 Oceanographers have not always been in complete agreement about the form of  the frequency spectrum. Nonequilibrium wave conditions, inadequate sampling times,  poor ground truth, etc., can contaminate the data set from which empirical spectra  are derived. However, by careful selection of data from many sources, ensuring that  only equilibrium (fully developed) sea conditions were represented and the wind was  always measured at the same reference height (usually taken as 10 meters), Pierson  and Moskowitz17 established a simple empirical spectrum that has proven popular and  useful. 
 PORT DEVICES IS DESCRIBED IN #HAPTER  OF 3HERMAN  4HE SUBTRACTOR OUTPUTS ARE CALLED  DIFFERENCE SIGNALS  WHICH ARE ZERO WHEN THE TARGET  IS ON AXIS  INCREASING IN AMPLITUDE WITH INCREASING DISPLACEMENT OF THE TARGET FROM THE ANTENNA AXIS 4HE DIFFERENCE SIGNALS ALSO CHANGE  n  IN PHASE FROM ONE SIDE OF CENTER  TO THE OTHER 4HE SUM OF ALL FOUR 
 RECEIVERS COHERENTSIGNALPROCESSING (c) XMTRANTENNATRANSMITTER CIRC. LOW-NOISEAMPLIFIERRCVR 1 CSP PHASEDETECTMONOPULSETABLE RCVR 2 CSP LOW-NOISEAMPLIFIERRECEIVERS COHERENTSIGNALPROCESSING . where/ = /(G) = A(0)/2(6), x = signal-to-noise ratio in the sum beam, and Various authors have defined the monopulse sensitivity factor in different ways.38 For the purposes of this chapter, the monopulse sensitivity factor is de- fined as the constant of proportionality required in the denominator of the rmse to convert the square root of twice the boresight signal-to-noise ratio in the beam to the rmse. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 25.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 Writing that impulse response as h(n) = hI(n) + jhQ(n), using real functions hI(n) and  hQ(n), the line 4 operation becomes  [line 5] = [line 3] ∗ h(n)   = [line 3] ∗ [hI(n)   + jhQ(n)]   = ([line 3] ∗ hI(n))   + j([line 3] ∗ jhQ(n))   = I5   + jQ5  where the fact that line 3 is real in the time domain was used in the last step. 
 The second most important item forthe operator tomonitor isthe radar crystal current. Ifthis maintains itsoriginal value, itisknown that thelocal oscillator isfunctioning and thecrystal hasnotchanged its properties. Adecrease may indicate aburned-out ordamaged crystal. 
 Sofarasthe authors ofthis book areconcerned, theword m.dar implies not only pulse radar, ashas already been remarked, but microwave pulse radar. Though itistrue that theefforts ofthe Radiation Laboratory were devoted exclusively to microwave pulse radar, this attitude isnot entirely parochialism. The fact isthat fornearly every purpose served byradar, microwave radar ispreferable. 
 The controls on indicator unit type 162 were: PPI brightness; PPI vertical shift (preset); PPI horizontal shift (preset); PPI focus control; Height tube brightness control; Height tube vertical shift (preset); Height tube focus (preset); Main tuning control; Mixer current control; Mixer coupling adjustment; Local oscillator coarse frequency control (inside unit). The local oscillator (LO) was installed in this unit because it was believed that it might require adjustment by the operator beyond simple tuning. The LO controlscomprise the mixer current control, the adjustment of the LO coupling and LO tuning. 
 Geosci. Remote. Sens. 
 414-464, September 1968. 18. Steenson, B. 
 CAL SOUNDERS AND OBLIQUE BACKSCATTER SOUNDERS FOR TRANSMISSION 
 ,/" - 4HIS SECTION ADDRESSES TOPICS THAT NEED TO BE CONSIDERED IN THE DESIGN OF RADAR $30 SYSTEMS AS WELL AS IMPLEMENTATION ALTERNATIVES 4IMING $EPENDENCIES  )N COHERENT RADAR SYSTEMS  ALL LOCAL OSCILLATORS ,/S   AND CLOCKS THAT GENERATE SYSTEM TIMING ARE DERIVED FROM A SINGLE REFERENCE OSCILLA 
 MM PHOTOGRAPHIC FILM  WHICH WAS PROCESSED THROUGH A COMBINATION OF OPTICAL AND DIGITAL MEANS FOLLOWING RETURN OF  !POLLO  TO %ARTH /PTICAL PROCESSING WAS THE  STATE 
 43, pp. 689-693, November, 1973.  21. 
 51–56, April 22, 1960.  4. P. 
 The  Woodward-Levinson synthesis technique consists in determining the amplitude and phase of  the uniform aperture distribution corresponding to each of the sample values and performing  a summation to obtain the required overall aperture distribution.  The aperture distribution may be found by substituting the antenna pattern of Eq. (7.26)  into the Fourier-transform relationship given by Eq. 
 IT-2, pp. 66-71, June, 1956. , .,  45. 
 PLES  NOT ON THE TOTAL NUMBER OF SAMPLES 4HE NUMBER OF INDEPENDENT SAMPLES CAN BE FOUND FROM %Q  OR %Q  AFTER SUITABLE ANALYSIS 4HIS  ANALYSIS ASSUMES THAT  ONLY DOPPLER FADING CONTRIBUTES TO INDEPENDENCE BUT MOTION FROM ONE CELL TO ANOTHER ALSO ADDS INDEPENDENT SAMPLES 4HUS  THE TOTAL NUMBER OF SUCH SAMPLES IS APPROXI 
 It is an iterative method that is a generalization of the k-means clustering algorithm. The K-SVD algorithm alternates between two stages: (1) sparse coding stage, and (2) dictionary update stage. In the ﬁrst stage, a pursuit algorithm is used to sparsely code the input data based on the current dictionary. 
 19.15  Active Seekers  ..................................................  19.15  Passive Seekers  ................................................  19.17 Other System Considerations  ............................ 
 5.4 Angular Resolution   The angular resolut ion can be calculated in a similar way as the range resolution, if pulse echoes  are replaced with the maximum of the directivity.  As a good approximation the half -power  beamwidth   γBWof the antenna can be utilized.  This is illustrated in Figure 5.6. 
 The electron-density distribution is the major control over the propagation of HF radio waves. Ground illumination over the horizon is enabled by refraction in the ionosphere. When an oblique-incidence radio wave traverses a path where elec- tron density is increasing with altitude, the ray is bent away from the vertical; if NOISE (dBW) IN A 5-kHz BAND FIXED STATIONAMA-TEURFIXEDMARINEMOBILEBROAD-CASTAEROFIXANDMOB. 
 I I, pp. 44-48, August,  1972.  36. 
 13.3, the value of a0 is seen to be  essentially independent of frequency for vertical polarization, except at low grazing angles.  With horizontal polarization, the clutter echo decreases with decreasing frequency. This is  most pronounced at the lower grazing angles. 
 Geophys. Res ., vol. 100, pp. 
 Z COORDINATE SYSTEM IS GIVEN IN 3ECTION  OF 7ILLIS  /THER COORDINATE SYSTEMS  INCLUDING THREE 
 deg/s the time waveform may be found from  Eq. (4.29) by dividing both the numerator and denominator of the exponent by {},. Letting  0/()1 = t, the time variable, and noting that 08/fJ1 = t0, the time on target, the modulation of  the received signal due to the antenna pattern is  ( ) k ( 2.776 t2 ) s11 t = exp -2 to (4.30) . 
 Here radar signals are rapidly attenuated. Very few microwave radars have  the capahilit~of penetrating the diffraction region to any great extent because of the severe  losses.  The effect of the round earth on radar coverage can be predicted by analytical means for  the idealized case of a "smooth" earth of known, uniform properties. 
 [ CrossRef ] 10. Pastina, D.; Colone, F.; Lombardo, P . E ﬀect of apodization on SAR image understanding. 
 -(Z STEPS OVER THE RADARS OPERATING BAND )N  THE PRESENT EXAM 
 Step 4 : Obtain Rlby Fourier transform ln (|I(k,n)|)·I∗(k,n)and calculate the w(m). Step 5 : Update phase error estimation ˆφ(m)and l=l+1, go back to Step 2. Update           ,        Calculate    Obtain Initial  Generate ISAR Image      llEI E I T!   wm ˆ  mI  ll NO EndYESCompensate Phase Error Calculate Entropy ˆ  mIRaw Data-like Data   Figure 4. 
 15.3.—Radar performance survey, 1943–1 944. July 1945. war. 
 A common strategy is to adopt the azimuth-range decouple operators in the algorithm. In this paper, the BP based azimuth-range decouple operators are adopted. The memory cost is reduced from O(n2)toO(n). 
 Fishbein, and 0. E. Rittenback: Continuous-Wave Radar with High Range Resolu- tion and Unambiguous Velocity Determination, I RE Trans., vol. 
 Young, Jr.: The Evolution of Ferrite Control Components, Micro\vui.t~ J..  vol. 21, pp. 
 The requirements forsatisfactory transmission ofthe outgoing pulse arerather easily met. 1.The loss inthe discharge across the gaps must beasmall fraction ofthe magnetron power. 2.The line must bematched when the gaps arefired. 
 2001 ,27, 23–30. [ CrossRef ] 8. Reinisch, B.W.; Huang, X.; Galkin, I.A.; Paznukhov, V .; Kozlov, A. 
 ELECTRONIC COUNTER-COUNTERMEASURES  24.676x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 190. S. L. 
 Figure 7.6illustrates the latter. The cathode-ray tube, whose face isprecisely spherical, ismounted with this face concentric with the spherical mirror ofthe optical system. Light from anintense mercury- arcortungsten source isconcentrated onthetube face bythelens-and- mirror arrangement shown. 
 71-79,  1958.  49. Brown. 
 BEAM CLUTTER  OVER THE )00S  AND SELECTING OR COMPUTING THE BEST WEIGHTING TO APPLY ACROSS THE #0) !NOTHER TECHNIQUE THAT IS APPLICABLE TO HIGH 
 ( from G. V . Trunk7) ch07.indd   5 12/17/07   2:12:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 It is equivalent to ordinary base-two addition with  only the least significant bit carried forward. A modulo-two adder is also called an exclusive-or  gate. An 11-stage shift register has a total of 2" different possible states. 
  
 RECEIVE POLARIZATION COMBINATIONS /NLY THE COPOLARIZED 66 AND CROSS 
 8.2, it is called a corporate feed, since it resembles (when turned upside  down) the organization chart of a corporation. Equal lengths of line transmit the energy to  each element so that no unwanted phase differences are introduced by the lines themselves. (If  the lines are not of equal length, a con~pensation in the phase shift must be made.) The proper  phase change for beat11 steering is introduced by the phase shifters in each of the lines feeding  the elements. 
 One procedure that  overcomes this limitation is known as common depth point surveying, which utilizes two  antennas in bistatic operation at a number of transmit and receive positions. The velocity of propagation is given by n  = (mo  mr eo er)–1/2; hence in a material  with mr = 1, the velocity becomes n  = c/(er)1/2. The phase velocity is given by n  = w  /b  and as  b=′+′′ ′  +      ωµε ε ε 21 12 (21.10) The phase velocity is also dependent on the factor e″/e′, which is also tan d. 
 The computer is needed in a phased-array radar to provide beam-steering commands for  the individual phase shifters; signal management by determining the type of wavdorm, the  number of observations, data rate, power, and frequency; the corresponding signal processi11g  and data processing in accordance with the mode of operation; outputs of processed daltl to \ ) . THE ELECTRONICALLY STEERED PHASED ARRAY ANTENNA IN RADAR 323  users. including the generation of displays;" housekeeping" functions of performance monitor­ ing. 
 Ó°£È  2!$!2 (!.$"//+  !NTENNA SCANNING ALSO CAUSES A SPREAD OF THE CLUTTER POWER SPECTRUM DUE TO THE  AMPLITUDE MODULATION OF THE ECHO SIGNALS BY THE TWO 
 Crowbars arc  usually required for high-power, hard-tube modulators because of the large amounts of stored  energy. They are also used with d-c operated crossed-field amplifiers and mod~anode pulsed  linear-beam tubes which are connected.directly across a capacitor bank. The line-type modu­ lator does not usually require a crowbar since it stores less energy than the hard-tube modula­ tor and it is designed to discharge safely all the stored energy each time it is triggered. 
 830–841, 2001. 128. J. 
 $OPPLER  "EAM 
 The background ionospheric effect can be mitigated using the split-spectrum method or using the ionospheric prior knowledge acquired from the global navigation satellite system (GNSS)/BeiDou system [ 15–18]. In recent papers, the multi-squint (MS) interferometry methodology is proposed [ 5], which provides a new ionospheric mitigation approach for SAR system with limited bandwidth. The scintillation effect is caused by small scale ionospheric turbulent irregularities, which typically occurs after the sunset in the equatorial and polar regions [ 14]. 
 AREA SURVEILLANCE  FREQUENT FREQUENCY CHANGES ARE  REQUIRED IN ORDER TO COVER THE VARIOUS RANGE EXTENTS )N ADDITION  RELATIVE PHASE OR TIME 
 A duplexer is included  in the sum arm for the protection of the receiver. The output of the phase-sensitive detector is . TRACKING RADAR 161  m M  (al (CI  fl  +  Angle  (bl {d)  Figure 5.7 Monopulse antenna patterns and error signal. 
 STATE POSITION  VELOCITY  AND ACCELERATION  +ALMAN FILTER  ESTIMATES TARGET MOTION IN AN INERTIAL COORDINATE SYSTEM -ULTIPLE 
 The RF signal to be amplified enters via the input coilpler and propa-  gates along the slow-wave structure. A helix is depicted as the slow-wave structure in Fig. 6.1 I,  but TWTs for radar usually use a structure better suited for high power. 
 £Î°Ç{  2!$!2 (!.$"//+    , 2 7HICKER AND # 7 9OUNG  h4HE EVOLUTION OF FERRITE C ONTROL COMPONENTS v  -ICROWAVE *   VOL   NO   PP n     * $I"ARTOLO  7 * )NCE  AND $ ( 4EMME  h! SOLID STATE @FLUX DRIVE CONTROL CIRCUIT FOR LATCHING 
 METER MAIN REFLECTOR  APERTURE 4HIS REFLECTOR  SHOWN IN &IGURE   IS USED FOR AN  3 
 4 OR MAGIC 
 THE 
 Stat. 2007 , 35, 2313–2351. [ CrossRef ] 16. 
 25.7  Isorange Contours  .............................................  25.8  25.5 Area Relationships  .................................................  25.9  Location  ............................................................ 
 BAND  AND IN 
 WEIGHT RATIO THAT MIGHT BE TWO TO THREE TIMES GREATER THAN THAT OF AN EQUIVALENT SINGLE 
 SITE REGION SEE 4ABLE   P2CAN VARY FROM nMS NEAR THE  BASELINE TO nMS WHEN  24   22   , 4YPICAL P2CONTOURS ARE SHOWN IN *ACKSON  4HESE RATES AND RATE CHANGES REQUIRE AN INERTIALESS ANTENNA  FOR EXAMPLE  A PHASED ARRAY WITH DIODE PHASE SHIFTERS .ORMALLY  A PHASED ARRAY ANTENNA USED FOR SURVEILLANCE IS PROGRAMMED TO SWITCH BEAMS IN INCREMENTS OF A BEAMWIDTH &RACTIONAL SHIFTS OF A BEAMWIDTH CAN BE ACHIEVED BY CHANGING THE PHASE OF A FEW SYMMETRIC  PAIRS OF PHASE SHIFTERS IN THE ARRAY )N THIS WAY  A PSEUDO 
 ALLY BEEN DETECTED BY THE RADAR !N AUTOMATIC RADAR TRACKING SYSTEM FORMS A TRACK WHEN ENOUGH RADAR DETECTIONS ARE MADE IN A BELIEVABLE ENOUGH PATTERN TO INDICATE A TARGET IS ACTUALLY PRESENT AS OPPOSED TO A SUCCESSION OF FALSE ALARMS  AND WHEN ENOUGH TIME HAS PASSED TO ALLOW ACCURATE CALCULATION OF THE TARGETS KINEMATIC STATEUSUALLY POSITION AND VELOCITY 4HUS  THE GOAL OF TRACKING IS TO TRANSFORM A TIME 
 BASED 3!2 AT  8 BAND )TS  M BY  M ANTENNA IS A TWO 
 17.14 and 17.15). When one orboth stations aremoving, onthe other hand, itisneces- sary either touse sufficiently wide antenna patterns toprovide coverage inallthe necessary directions, orelse toprovide forautomatic pointing ofthe antenna, with the consequent added complexity and weight. (If several receiving stations are involved the transmitting antenna must cover them all.)Asaresult, lower frequencies (100 to900 Me/see) have predominated insuch applications since more power isavailable and higher antenna gains can beobtained with agiven pattern. 
 DIGITAL CONVERTER .EARBY EMITTERS CAN SIGNIFICANTLY RAISE THE SYSTEM NOISE LEVEL  SIMPLY THROUGH SPEC 
 When the target was on axis, the two pulses were of equal amplitude (Fig. 18.20); when the target moved off axis, the two pulses became unequal (Fig. 18.2b). 
 CW AND FREQUENCY-MODULATED RADAR 97  Irorii tlic ~iietl~ocls descri1,ed ill Scc. 11.1. It ciiri be sllown that the tlreoretical rrils range error is  bet ere E = energy cor~tairled in received signal and No = noise power per hertz of bandwidth. 
 Bothaccurate andunambiguous range measurements canbeIlndebytransmitting threeormorefrequencies insteadofjusttwo. Forexample, iftht:threefrequencies I"12'and13aresuchthat13-I,=k(f2-II)'where kisafactoroftheorderof10or20,thepairoffrequencies 13,IIgivesanambiguous but accurate rangeme:')urement whilethepairoffrequencies 12,IIarechosenclosetoresolve theambiguities inthe13,IImeasurement. Likewise, iffurtheraccuracy isrequired afourth frequency canbetransmitted anditsambiguities resolved bythelessaccurate butunambiguous I/lCaSllrelllcnt ohtained fromthethreefrequenciesII'12,.f3'Asmorefrequencies areadded, thespectrum andtargetresolution approach thatobtained withapulseoral\FM-CW waveform. 
 Anintegrator basedonthetappeddelaylineisshownin Fig.to.9.Thetimedelaythrough thelineismadeequaltothetotalintegration time,andthe tapsarespacedatintervals equaltothepulse-repetition period.Thenumberoftapsequalsthe numberofpulsestobeintegrated. Theoutputsfromeachofthetapsaretiedtogether toform thesumoftheprevious npulses.Oneoftheadvantages ofthisintegrator isthatanytypeof weighting maybeappliedtotheindividual pulsesbysimplyinserting theproperattenuation ateachtapofthedelayline. Thisformofintegrator thatsumsthelastnpulsesisalsoknownasthemoping-window detector ortheanalogmoving-window detector.64'It,ofcourse,canalsobeimplemented in digitalcircuitry.Itissimilartothebinarymoving-window detector discussed above,butit doesnotuseadoublethreshold anditdoesnotsuppress theeffectsoflargeinterference spikes asdoesthebinarydetector.ItdoesnotsutTerthe1.5to2dBlossofthebinarydetector andit canbeemployed toestimate thetarget'sanglebybeamsplitting. 
 The master-condenser is C in the anode circuit  of valve Va. This condenser will, as we have seen,  charge in linear fashion through the pentode, thus  carrying the cathode of valve V6 more and more negative  with respect to its anode. The control grid of this valve  is, however, appreciably negative relative to the anode  due to the voltage drop in Re by the anode current of Vc. 
  ENJOYED ABOUT ONE YEAR OF  SIMULTANEOUS OPERA 
 COMPUTED DATA DISPLAYED THREE 
 W. Ganz, “CPCT antennas for AMTI radar, vol. 2: Theoretical study,” Air  Force Avionics Lab. 
 The noise figure of the ordinary "broadband" mixer whose image frequency is ter-  minated in a matched load is not shown in Fig. 9.4. It would lie about 2 dB higher than the  noise figure shown for the image-recovery mixer. 
 Itisalso possible toachieveamulticolor tubewithvariable persistence. Although colordisplays maybepleasing andattractive totheoperator, theapplications inwhichtheyhaveprovensuperior toproperly codedmonochromatic displays apparently arefewerinnumber thanmighthavebeenanticipated.58 Brightdisplays. Thereareapplications whereitisnotpossible orconvenient tousethe conventional CRTdisplaythatrequires adarkened environment; suchasinthecockpitofan aircraftoranairfieldcontrol tower.Oneformofbrightdisplay isthedirect-view storage ("he.31Itnotonlyoperates underambient lightconditions, butitcanprovide avariable persistence. 
 The letter T is used for ground equipment that is normally moved from place to place and is not capable of operation while being trans- . ported. The letter V is used for equipment installed in a vehicle designed for func- tions other than carrying electronic equipment (such as a tank). 
 This is accomplished by comparing signals received  simultaneously in two or more antenna beams, as distinguished from techniques such  as lobe switching or conical scanning, in which angle information requires multiple  pulses. Effective monopulse jamming techniques generally attempt to exploit the mon - opulse radar’s susceptibility to target glint or multipath signals.13 One jamming approach, known as cross-eye , used against monopulse radars gener - ates artificial glint into the monopulse tracking loop.13 The inventors of the cross-eye  technique are B. Lewis (NRL, USA) and D. 
 BEAM NOISE JAMMING  THE RECEIVED JAMMING POWER INCREASES DIRECTLY  AS 'T  RESULTING IN A NET INCREASE IN SIGNAL 
 Ahalf wavelength farther down the guide, and onthesame side astheAFC attenuator, is found theduplexer T. The TR cavity isiris-coupled, both ontheinput side from theend ofthewaveguide and ontheoutput toacoaxial mixer which isotherwise thesame astheAFC mixer. AsintheAFC case, i-f cables connect the mixer with the local oscillator and the proper parts ofthe receiver. 
 11.21), exhibiting the same kind of un- dulations noted earlier in the case of the metallic sphere. These undulations are caused by creeping waves that propagate around the rear of the cylinder just as they do around a sphere. However, the peaks and nulls of the sphere and cylinder interference patterns are not perfectly aligned with each another, suggesting that the relative phase angles between the creeping waves and specular contributions are slightly different for the two geometries. 
 Antennas for small craft are normally housed within a radome, which protects the  antenna and up-mast electronics of the radar environmentally and prevents the  antenna from snagging the rigging. In particular, it assures that there is no danger to  ch22.indd   11 12/17/07   3:02:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 2.2 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 at greatly extended ranges, which exacerbates the problems with birds and automobiles,  and can also cause the detection of fixed clutter hundreds of kilometers away. 
 The principal advantage of not using feedback is the  excellent transient response of the canceler, an important consideration in a phased  array or when pulse interference noise is present. If a phased array radar should use a  feedback canceler, many pulses would have to be gated out after the beam has been  repositioned before the canceler transient response has settled to a tolerable level.  An initialization technique has been proposed27 to alleviate this problem, but it pro - vides only partial reduction in the transient settling time. 
   Ç°{Î &)'52%   4HE RETROSPECTIVE PROCESS A  A SINGLE SCAN OF DATA   B  EIGHT SCANS OF DATA  AND  C  EIGHT  SCANS OF DATA WITH TRAJECTORY FILTERS APPLIED AFTER 0RENGAMAN ET AL Ú )%%%  . Ç°{{  2!$!2 (!.$"//+  WHERE K& IS THE RATIO OF THE SIZE OF THE POSSIBLE SPACE A TARGET CAN TRAVEL IN ONE DETECTION  INTERVAL TO THE SIZE OF ENTIRE CLUTTER REGION '   L&$6 '  -!8    AND K0 IS THE RATIO OF THE SIZE OF A RADAR RESOLUTION CELL TO THE SIZE OF THE ENTIRE CLUTTER  REGION '  LTT 0$ '     SI BEING THE RESOLUTION hDISTANCEv IN THE  ITH DIMENSION  AND  F¼$  .  -  BEING THE COM 
 DOPPLER COUPLING OF THE LINEAR 
 and its surface temperature falls, but there is little or no change in the temperature of the  upper atmosphere. This leads to conditions favorable to ducting, that is, a temperature inver­ sion at the ground and a sharp decrease in the moisture with height. Therefore, over land  masses ducting is most noticeable at night and usually disappears during the warmest part of  the day. 
 Another electro~neclianical phase shifter which has been used in array radar is the  rotatitig-arm nieclianical phase sIii~ter.".~~+~~ It consists of a number of concentric transmis-  siori lilies. E;icli line is a tliree-sided squiire trough with an insulated conductor passing down  the middle. A moving arrrl makes contact with each circular assembly. 
 The sidelobe structure of each half of the autocorrelation function has odd sym- metry about this value. The periodic autocorrelation function may be viewed as being constructed by the superposition of successive aperiodic auto- correlation functions, each displaced in time by AfT units. The odd symmetry exhibited by the aperiodic function causes the sidelobe structure for the peri- odic function to have a constant value of — 1. 
 The orbit’s  inclination should be near 50 °–63° to resolve north and east slopes nearly equally  and to cover the lower latitudes where existing data are inadequate. Note that oceano - graphic radar altimeter missions (TOPEX/Poseidon, Jason-1, ERS1/2, ENVISAT, and  Geosat ERM/GFO) are normally placed into exact-repeat orbits (10 to 35 days), and  as a consequence, have widely spaced (80 km to 315 km) ground tracks. Such orbits   cannot resolve the short-wavelength two-dimensional surface slopes required for use - ful geodesy. 
 The 'two signals  travel in opposite directions and arc received at each end of the feed. The phase difference  between the two signals (or the difference in travel time) depends on from which slot they  originated. which in turn depends on the elevation angle of arrival. 
 BASED IMAGING RADAR DATA  USED FOR AGRICULTURE AND FOREST MANAGEMENT  AND FOR MEASURING CHANGES IN ITS ALPINE GLA 
 C>7 Thestandard deviation ofangularestimates obtained withthesingledelay-line isabout15 percentgreaterthantheoptimum estimates hasedontheCramer-Rao lowerhound.C>C>Ifthe maximum valueoftheoutputisusedasanestimator ofthetargetlocation, thebiasis constant. However, thestandard deviation oftheestimates are100percentgreaterthanthe optimum.66Similarly thestandard deviation ofthedouble-loop integrator usingthemaxi­ mumvalueastheestimator produces astandard deviation 50totOOpercentgreaterthanthe optimum. Thetwo-pole filterofFig.IO.lOe,ontheotherhand,hasastandard deviation 15 percentgreaterthanoptimum, andtheestimator basedonthemaxiwumvaluehasaconstant bias.66Itsrelatively goodangle-estimating accuracy, gooddetection performance, alongwith therelativesimplicity ofafeedback integrator makesthetwo-pole filteragood...}choice asan automatic detector forscanning radars. 
 Each array of a 4-face array, for example, woulJ  scan ± 55°. To minimize the loss in gain, each face would be tilted back an angle of 35.3° from  the vertical. Elements are arranged in an equilateral triangular pattern with element separa- Table 8.3 Properties of hemispherical coverage arrays 123  Number of faces 3 4 s 6  Maximum scan angle 63.4° 54.7° 47.1° 40.7°  Tilt angle 26.6" ' 35.3° l S.5° 20.4°  Element spacing (wavelengths) 0.628 0.691 0.679 0.700  Maximum power reflected 14% 7% 4% J 0/  -lo  Maximum beam broadening 2.2 l. 
 Then there are two different types of  radars called, in the past, track-while-scan . (ii) One is a limited angle scan as in some  air-defense radars and aircraft landing radars, which search a limited angular sector  at a rapid rate (e.g., 10 or 20 times a second). (iii) The other type of track while scan  (TWS) was what is now called automatic detection and tracking (ADT). 
 202 -21 1, 1958.  67. Brennan, L. 
 ch05.indd   4 12/17/07   1:26:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 
 16. Villard, 0. G., Jr.: The Ionospheric Sounder and Its Place in the History of Radio Science, Radio  Science, vol. 
 37. Bottou, L. Large-scale machine learning with stochastic gradient descent. 
   !      $!   "   % !       !!         &)'52%     2-3 ANGLE SCINTILLATION BASED ON THE THEORETICAL RELATION TO THE RADIUS 
 In these systems, there is one receiver channel for each beam, and STC may be applied to the receiver channels independently. Consequently, the upper- beam receivers may be allowed to reach maximum sensitivity at short ranges, whereas the lower-beam receiver reaches maximum sensitivity only at long range. Most modern radars generate STC waveforms digitally. 
 Themonitoring ofthenoisefigurecanbeaccomplished eitherautomatically or manually bytheoperator. Thereceiver noise-figure canbemeasured withabroadband noisesourceofknown intensity, suchasagas-discharge tube22orasolid-~tate noisesource.Thenoisefigureis determined bymeasuring (1)thenoisepoweroutputN1ofthereceiver whenamatched impedance attemperature To=290Kisconnected tothereceiver inputand(2)thenoise poweroutputN2whenamatched noisegenerator oftemperature T2isconnected tothe receiverinput.2Thetemperature T2istheequivalent noisetemperature ofthebroadband noise ;enerator. Thenoisefigurecanbeshowntobe (9.10) whereY=N 2/N1• Themeasurement ofnoisefigurecanbemadeduringradaroperation withoutdegrading thereceiver sensitivity bypulse-modulating thenoisesourceinsynchronism withtheradar triggerandinjecting thenoiseintothereceiverduringthe"f1yback"or"deadtime"ofthe radar,justpriortothetriggering ofthenexttransmitter pulse.Themeasurement ofthe receiveroutputwiththenoisesourceon(N2)andthenoisesourceoff(Ndcanbemadeon alternate pulseperiods. 
 in a sense, used the principle of frequency scan without  the necessity of changing the radiated frequency. The introduction of digitally switched phase  shifters employing either ferrites or diodes in the early 1960s made a significant improvement  in the practicality of phased arrays that could he electronically steered in two orthogonal  angular coordinates.  8.2 BASIC CONCEPTS  ;\11 array antenna consists of a number of individual radiating elements suitably spac":d with  respect to one another. 
 The advent of radar to detect our own ships and to ﬁnd and ﬁght the enemy at sea would bring about major changes in the function of aircraft in maritime warfare. A comprehensive history of Coastal Command is given in the book by C Ashworth [ 2] and the story of its wartime years is given in the book by A Hendrie doi:10.1088/978-1-6432-7066-1ch1 1-1 ªMorgan & Claypool Publishers 2018. [3]. 
 BAR HAS BROADER BANDWIDTH AND HIGHER EFFICIENCY THAN THE COUPLED 
 E., and M. Bernfeld: "Radar Signals," Academic Press, New York, 1967.  25. 
 One is a normal video channel. In the other, the video signal experiences a  time delay equal to one pulse-repetition period (equal to the reciprocal of the pulse-repetition  frequency). The outputs from the two channels are subtracted from one another. 
 (1 1.53)]. The composite three-  dimensional ambiguity surface is shown in Fig. 11.9~. 
 Many theoretical models for radar return from the ground assume a rough boundary surface between air and an infinite homogeneous half space. Some include either vertical or horizontal homo- geneities in the ground properties and in vegetative or snow covers. *Angle of reflection equals angle of incidence.P BAND. 
 WAVE FREQUENCIES 4HE SOLID 
 Two examples of long-range radar applications generally requir - ing very high antenna gains are (1) missile defense radar and (2) space-based radar. Limited Scan Radars.  Some radars operate over a limited field-of-view and/or the  requirements dictate fast electronic scanning over a small FOV and slower mechanical  scanning over a larger field of view. 
 The Z plane is the comb-filter equivalent  of the S plane23 with the left-hand side of the S plane transformed to the inside of the unit  circle centered at Z = 0. Zero frequency is at Z = 1 + j0. The stability requirement is that  the poles of the Z transfer function lie within the unit circle. 
   .   NUMBER OF )00S IN #0)  RC   STANDARD DEVIATION OF CLUTTER SPECTRUM  +   FILTER NUMBER +    IS THE $# FILTER   4   INTERPULSE PERIOD #LUTTER 
 ≥ Sr ≥ .  ≥ SA rank-selection r with sum-values Sr. ∑ ∑∑∑∑ ∑∑∑ . 
 Kelleher, K. S., and C. Goatley: Dielectric Lens for Microwaves. 
 The delay lines should becapable of matching each other within this tolerance foratleast anhour atatime. Likewise the amplitudes ofthe signals inthe delayed and undelayed channels should match to4percent foranhour atatime. Modulator. 
 each withdifferent scattering properties. Also,interactions mayoccurbetween thescattcrers which affecttheresultant crosssection. Anexample ofthecrosssectionasafunction ofaspectangleforapropeller-driven Spherer-{------1 Sphere torget torget Rodar Figure2.14Geometry ortheIwo-scallcrcr complextarge!.. 
 "   
 (Reprinted in ref. 18.)  25. Hannan, P. 
 132- 148.  74. Carter, P. 
 1037–1044, 1980. 120. F. 
 The fluctuation isnow given bytheexpression Ay, =k yl ~’(8) where kisnolonger aconstant butdepends ontheratio ofmaximum input signal yOtothelimit level vI,asshown inTable 16.3. TABLE 16.3 yo ;1 k 10 5.1 100 7.2 1000 8.7 Itwillbenoticed that kdoes notchange much astheinput signal strength isvaried over awide range. This makes iteasy toobtain removal of clutter ofvarying size. 
 All practical integration techniques  employ some sort of storage device. Perhaps the most common radar integration method is  the cathode-ray-tube display combined with the integrating properties of the eye and brain of  the radar operator. The discussion in this section is concerned primarily with integration  performed hy electronic devices in which detection is made automatically on the basis of a  threshold crossing. 
 3.16] CITIES 107 portion ofNew York City inwhich immediate identification ispossible byreference tothe Hackensack, Hudson, Harlem, and East Rivers, together with Central Park andthe various bridges. Itissometimes possible todiscern afew prominent features ofthe street pattern ofacity. Acomplete presentation ofthe street pattern would beideal, but present radar equipment lacks the resolution which N FIG.3.32.—Obihiro, Hokkaido, Wavelength =3.2cm,3°beam, altitude 12,000ft, radius 15nautical mi. 
 Cooper: An Analysis of the Performance of Weighted Integrators, IEEE  Trans., vol. IT-10, pp. 296-302, October, 1964. 
 This autocorrelation func- tion for g is given by Eq. (21.24). It will be noted that the autocorrelation function of g is a function of the difference in range R-R'. 
 arid R. A. Ferrero: Clriderstanding AID atid D/A Converters, IEEE Spectrtrm, vol. 
 Strauch, R. G., D. A. 
 6ERTICAL 0ROBLEM  -OST PUBLISHED RADAR RETURN DATA PURPORTING TO INCLUDE  VERTICAL INCIDENCE GIVE VERTICAL 
 SCANNED ANTENNA  OR  INVERSE #ASSEGRAIN   PROVIDES USEFUL APPLICATIONS TO MONOPULSE RADAR 4HE TECHNIQUE  USES A RADOME 
 Considerations Related to Sub-array Adaptivity.  Tapering at the array element level  produces unequal noise power at sub-array outputs because of the different number of  elements in each sub-array. Adaptivity would try to equalize the noise between chan - nels, thus negating the tapering effect.119 The transformation T that encodes the sub-array   architecture * should be such that THT = I. 
 20.8  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 The long observation time for a skywave radar is needed to obtain the necessary echo  signal energy to ensure reliable target detection as well as to obtain the long integra - tion times needed for effective doppler processing. The ionosphere has a dominating  influence on skywave radar, whereas the normal atmosphere has very little effect on  microwave radar. The skywave radar’s frequency and other parameters are driven  primarily by the need to propagate via the ionosphere. 
 Figure 7.22 The "tin-hat" geodesic analog of a two-  dimensional Luneburg lens.  RADAR ANTENNAS 253 Thedielectric materials mustnotbetooheavy,yettheymustbestrongenoughtosupport theirownweightwithout collapsing. Theyshouldhave lowdielectric lossandnotbeaffected bytheweather orbychanges intemperature. 
 20° Limilfor-50°6 d=0,6A t~ --60°o95 ----------------- .._----------------.--.-,-,-,---..---,--,.--,--,---,----y-,- Figure8.15Scanangle00versusfrequency ..focorresponds to00=0_Dashedcurvegivesonsetofgrating lobeford=0.5Ao;dot-dash curveford=0.6Ao. traveldownthetransmission line.Thefinitetimeimpliesafinitebandwidth. Thegreaterthe wrap-up factor,thelessthefrequency bandrequired tosteerthebeamoveragivenangle; however, thelongeritwilltaketofillthearrayandthelesswillbethebandwidth thatthearray cansupport. 
 57. J. J. 
 A. Voyevodin, “Determining elements of drift of the ice cover and  movement of the ice edge by the aid of the ‘Toros’ side scanning radar station,” Probl. Arktiki  Antarkt  (in Russian), vol. 
 An example  of this type of antenna, produced by Kelvin Hughes, is illustrated in Figure 22.3. Small craft radars have used printed arrays for some years, as well as slotted  waveguide arrays. Small, horn-fed parabolic reflector systems have also been used. 
 93  11.4.2 Measurement of The Complex Polarization Scattering Matrix .............................. 93  11.4.3 Calibration and Error Correction for Polarimetric RCS Measurements ................. 95  11.5 Radar Cross- Section of Simple Objects ....................................................................... 
 PASS )N3!2  !LLEN  GIVES SEVERAL EXAM 
 But we shall find the working principles of radar simpler to follow if we begin at the receiver end. So let us go on to see what we need in a radar receiver, and how we Shali display the results on a CRT.  . 
 1.Since one pulse, the trigger, isinvolved inany method, adequate protection against pulse interference must beprovided inany case. 2.When time sharing isused within theradar cycle, thepulse methods require less complex r-fequipment than dothe c-w methods with their requirement foratleast one subcarrier. Were time sharing with thevideo signals abandoned and the pulses sent onasub- carrier, the additional complications would becompensated by considerable simplification and increased effectiveness ofthetermi- nalequipment. 
 46–48,   August 1982. 28. Editor, “Special series: Israeli Avionics-2,” Aviat. 
 This reverse-directed power results from mismatch at the CFA output that sends power back through the low-loss structure of the CFA. For example, a load with 1.5:1 VSWR reflects power 14 dB down. At cer- tain frequencies, this reflected power will combine with reflections inside the tube and may typically return to the input of the CFA at a power level only 8 dB down from full output power. 
 When the noise, or clutter, is  not described by a Rayleigh pdf, the receiver model of Chap. 2 is not optimum and can cause  degraded performance. The higher "tails" of the probability density function of non-Rayleigh  clutter mean that there will be a greater number of false alarms in the conventional receiver  designed on the basis of Rayleigh statistics. 
 and S. Weintraub: The Constants in the Equation for Atmospheric Refractive Index at  Radio Frequencies. Proc. 
 CHANNEL RADAR !DVANCED IMPLEMENTATION TECHNOLOGY AND EXPERIMENTAL RESULTS v  0ROC OF )NT  2ADAR 3YMP  )23  "ERLIN 'ERMANY   3EPTEMBER n    PP n  # - 2ADER  h7AFER SCALE INTEGRATION OF A LARGE SCALE SYSTOLIC ARRAY FOR ADAPTIVE NULLING v  4HE  ,INCOLN ,ABORATORY *OURNAL  VOL   NO   PP n    # - 2ADER  h6,3) SYSTOLIC ARRAY FOR ADAPTIVE NULLING v  )%%% 3IGNAL 0ROCESSING -AGAZINE     VOL   NO   PP n  *ULY   3 0 !PPLEBAUM  h!DAPTIVE ARRAYS v 3YRACUSE 5NIVERSITY 2ES EARCH #ORPORATION 2EPT 30, 42  n   4HIS REPORT IS REPRODUCED IN  )%%% 4RANS  VOL !0n  PP n  3EPTEMBER   , % "RENNAN AND ) 3 2EED  h4HEORY OF ADAPTIVE RADAR v  )%%% 4RANS  VOL !%3 
 #/5.4%2-%!352%3   Ó{°{x 4HE SCHEME IS BUILT AROUND TWO CLOSED LOOPS I  THE LOOP ENCOMPASSING THE RADAR  MODEL  THE TRACKING FILTER  AND THE SCHEDULER  AND II  THE TRACKING FILTER LOOP 4HE SCE 
 However,  some random selections may be better suited than others for radar application. 66 One criterion  for the selection of a good "random" phase-coded waveform is that its autocorrelation func­ tion should have equal time-sidelobes. (Recall from Sec. 
 17.22, converting gR/R0 to SNR9 and solving the resultant simultaneous equations. The cumulative probability of detection (probability of detecting the target at least once in k scans), Pck, is defined as k Pck=l- U[I - PM (17.26) /=i where PJ(i) is the probability of detection on the /th scan. The cumulation may occur over a variable number of scans, such as when it begins at a range where PJJ) is approximately zero, or over a defined number of scans, where a 1-out- of-N acquisition criterion must be satisfied. 
 Examples of cosecant-squared-pattern  synthesis are given in the literature.7•73•77•90  The cosecant-squared pattern may be approximated with a reflector antenna by shaping  the surface or by using more than one feed. The pattern produced in this manner may not be as  accurate as might be produced by a well-designed array antenna, but operationally, it is not  necessary to approximate the cosecant-squared pattern very precisely. A common method of  producing the cosecant-squared pattern is shown in Fig. 
 The  build-up of oscillations in a lightly loaded magnetron is more ideal; however, the magnetron In  this region may perform poorly by showing signs of instability which take the form of arcing  and an increase in the number of missing pulses. Poor performance is a result of the higher RF  voltages when operating in the antisink region, making RF discharges more likely.  In a radar with a rotating antenna, the phase and/or magnitude of the VSWR might vary  because the antenna will experience a different load impedance depending on the environment  it views. 
 I!.. and P. N. 
 In summary, the cases considered by Swerling are as follows: Case 1 Eq. (2.23), slow fluctuation Case 2 Eq. (2.23), fast fluctuation Case 3 Eq. 
 We note ascarcity ofexcessively high peaks: this isnot surprising asitisunlikely that very high peaks, being inany case infre- quent events, should occur atthesame place ontwo original traces. In Fig. 2.6c, four sweeps with noise have been averaged, and wenotice a further reduction inthemagnitude ofthefluctuations. 
 WAVEHEIGHT ASSUMPTION ON WHICH  THIS MODEL RESTS IS VIOLATED ON ANY REAL SEA SURFACE 4HE SMALL 
 I,.: f:val~rnliori of l'rack-While-Scan Cornputer Logics, chap. 29 of " Radar  ~l'cclirliqucs Tor 1)ctcctiori. -l'ri~ckirig, and Navigation." W. 
 BAND SYSTEMS + U  +  AND +A "ANDS  TO  '(Z   !S ONE GOES TO HIGHER RADAR FREQUENCY   THE PHYSICAL SIZE OF ANTENNAS DECREASE  AND IN GENERAL  IT IS MORE DIFFICULT TO GENERATE LARGE TRANSMITTER POWER 4HUS  THE RANGE PERFORMANCE OF RADARS AT FREQUENCIES ABOVE 8 BAND IS GENERALLY LESS THAN THAT OF 8 BAND -ILITARY AIRBORNE RADARS ARE FOUND AT + U  BAND AS WELL AS AT 8 BAND 4HESE FREQUENCY BANDS ARE ATTRACTIVE WHEN A RADAR OF SMALLER SIZE HAS TO BE USED FOR AN APPLICATION NOT REQUIRING LONG RANGE 4HE !IRPORT 3URFACE $ETECTION %QUIPMENT !3$%  GENERALLY FOUND ON TOP OF THE CONTROL TOWER AT MAJOR AIRPORTS HAS BEEN AT + U BAND  PRIMARILY BECAUSE OF ITS BETTER RESOLUTION THAN 8 BAND )N  THE ORIGINAL + BAND  THERE IS  A WATER 
 1112 magnetrons ofthis power; thus the tube isbetter able tofurnish the long 5-psec pulse without sparking. Itscooling blower also provides the general aircirculation inside ther-fhead. The waveguide fittings inside ther-fhead arenot airtight; they com- municate the head pressure tothe antenna waveguide run. 
 DOPPLER OFFSET FROM THE TRANSMIT CARRIER FREQUENCY 4HE SIDELOBE CLUTTER IS USUALLY SMALL COMPARED WITH MAIN 
 VIDE THE NECESSARY MEASUREMENT ACCURACIES REQUIRED BY THE TRACKER 4HIS ADAPTIVE TRACK UPDATE WAVEFORM ALLOWS THE SEARCH REVISIT TIME TO BE MAINTAINED WHILE TRACKING MULTIPLE TARGETS {°ÈÊ ,  
 For white noise [Ni(f )I2 = constant and the  N W N matched-filter frequency-response function of Eq. (10.19) reduces to that of Eq. (10.15). 
 FIELD STRENGTH OF THE INCIDENT WAVE IMPINGING ON THE TARGET AND  %S IS THE ELECTRIC 
 I.:-Ccun~nc!n! VII tI~~.c.A~~gu~.~r.I.I,R~_s_so!~~!ioQn~C.~, Pmc. IEEE, vol. 63, pp. 
 #7 3YSTEMS  4HE SIMPLEST SCATTEROMETER USES A STATIONARY #7  RADAR 3UCH SYSTEMS ARE NOT VERY FLEXIBLE  BUT THEY ARE DISCUSSED HERE IN SOME DETAIL TO ILLUSTRATE CALIBRATION TECHNIQUES THAT ALSO APPLY TO THE MORE COMPLEX SYSTEMS 4HE #7 SCATTEROMETER IS SHOWN IN BLOCK FORM IN &IGURE  4O EVALUATE  R   THE  RATIO OF TRANSMITTED TO RECEIVED POWER IS REQUIRED 4HE SYSTEM DEPICTED IN &IGURE  A  MEASURES TRANSMITTER POWER AND RECEIVER SENSITIVITY SEPARATELY 4HE TRANSMITTER FEEDS AN ANTENNA THROUGH A DIRECTIONAL COUPLER SO THAT A PORTION OF THE ENERGY MAY BE FED TO A POWER METER 4HE RECEIVER OPERATES  FROM A SEPARATE ANTENNA ELECTRICALLY ISOLATED  4HE  OUTPUT OF THE RECEIVER IS DETECTED  AVERAGED  AND DIGITALLY REC ORDED )TS SENSITIVITY MUST  BE CHECKED BY USE OF A CALIBRATION SOURCE 4HE CALIBRATED SIGNAL MAY BE FED THROUGH THE RECEIVER AT A TIME WHEN THE TRANSMITTER IS OFF &IGURE  B SHOWS A SIMILAR ARRANGE 
 During transmission (Fig. 9.7a) the ATR tubes located in a mount between the two  short-slot hybrids ionize and allow high power to pass to the antenna. Dashed lines show the  flow of power. 
 5“15and the operation may be described asfollows. If,asweshall assume forpurposes ofexplanation, only asingle target istobeobserved, the transmitter isturned onfor half the keying cycle and offduring the other half bymeans ofthe modulator, square-wave generator, TR and ATR tubes. Ifamul- tiplicity oftargets must behandled, the transmitter pulse ismade correspondingly shorter. 
 For example, when LI(RT + RR)] = 0.95, Pmax = 143.6° and (SIN)1 at pmax is 20 dB less than at Pmin- 25.5 AREARELATIONSHIPS Location.1'15'16'18'46-48'73'79-83 Target position relative to the receive site (0^, RK) is usually required in a bistatic radar. The receiver look angle 8^ is measured directly, or target azimuth and elevation measurements are converted directly to 8/?. Beam-splitting techniques can be used to increase the measure- ment accuracy. 
 BAND WAVEFORMS EMPLOYED  THE LOW FREQUENCIES  AND THE NATURE OF THE TRANS 
 Andrews, “HDTV-based passive radar,” presented at AOC 4th Multinational PCR Conference,  Syracuse, NY , October 6, 2005. 52. R. 
 With the BP based operators, the memory cost can be reduced dramatically. If we reconstruct the measurement matrix, the memory cost is O(PQMN ). With the BP based operators, the memory cost is O(MN). 
 ASPECT TARGET DETECTABILITY !LL 
 PASS COVERAGE OF SELECTED SITES IN GROUPS OF EIGHT OR MORE  
 TRACKING PROBLEMS INVOLVE TARGETS THAT DEVIATE FROM LINEAR MOTION IN MORE COMPLEX WAYS EG  COURSE CORRECTIONS  TERRAIN FOLLOWING  EVASIVE MANEUVERS  AND ATMOSPHERIC DRAG  4HE +ALMAN FILTER IS TUNED TO A PRACTICAL RADAR 
 SURFACE PARAMETERS FROM THE  %23 WIND SCATTEROMETER v  )%%% 4RANSACTIONS ON 'EOSCIENCE AND 2EMOTE 3ENSING   VOL     PP n    $ ' ,ONG  - 2 $RINKWATER  " (OLT  3 3AATCHI  AND # "ERTOIA  h'LOBAL ICE AND LAND CLIMATE  STUDIES USING SCATTEROMETER IMAGE DATA v  %/3  4RANS !MERICAN 'EOPHYSICAL 5NION  VOL     PP     - 2 $RINKWATER  $ ' ,ONG  AND ! 7 "INGHAM  h'REENLAND SNOW ACCUMULATION ESTI 
 DOPPLER RADAR NETWORK v*OURNAL  OF !PPLIED -ETEROLOGY  VOL   PP n  $ECEMBER   * 7URMAN  - 2ANDALL  # , &RUSH  % ,OEW  AND # , (OLLOWAY  h$ESIGN OF A BISTATIC DUAL 
 15. Cook. C. 
 8  WHICH IS MEANT TO BE A FUNCTIONAL COPY  4HESE TWO WILL CO 
 Simulated Experiment To test the performance of the proposed algorithm a simulated point target on a noise ﬂoor has been used. The simulated azimuth antenna beam pattern was shaped by a Hanning window. The simulated raw data matrix was affected by AWGN with a low SNR. 
 OFF %#- SYSTEMS EMPLOY HIGH 
   4HE DELETERIOUS EFFECTS OF PLATFORM MOTION CAN BE REDUCED BY PHYSICALLY OR ELECTRONI 
 TEMS MUST MEET )-/ REQUIRES THAT THE TREND IN A TARGETS CHANGE OF DIRECTION IS SHOWN WITHIN ONE MINUTE AND THE PREDICTION OF THE TARGETS MOTION SHOULD BE AVAILABLE WITHIN THREE MINUTES  AS GIVEN IN 4ABLE  )N PRINCIPLE  TARGET TRACKING COULD BE AIDED BY DATA FROM !)3 3ECTION    (OWEVER  !)3 DATA IS BEST LEFT OUT OF THE RADAR TRACKING PROCESS IN ORDER TO KEEP THEM ENTIRELY INDEPENDENT /NCE RADAR TRACKS HAVE BEEN FORMED  THEY  CAN THEN BE AUTO 
 $OPPLER 3CATTEROMETERS  ! CONVENIENT WAY FOR AN AIRBORNE MEASUREMENT  IS TO MEASURE THE SCATTERING COEFFICIENT AT MANY ANGLES SIMULTANEOUSLY WITH A #7 SYS 
 SPACE-BASED REMOTE SENSING RADARS  18.456x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 Venera 15/16 , simultaneous “twin” missions, were the first space-based SAR map - pers of another planet. They imaged the area from the north pole down to about 30 °N  latitude over 8 months of operations.100 Their radars had two modes, imaging and altim - etry, operating at 8-cm wavelengths. Imaging resolution was ∼1 km. 
 it is located at one other place named Houhu (Figure 4). Compared to the work of Bai et al. some places within major areas of subsidence exhibit a considerable increase in subsidence velocity. 
 Illerefore, over the grazing angles of usual interest. a radar  wliicll 11i11st clctcct titrgcts over land lias a more difficult task than one which must detect  targcts over tl~c sca. I;vcr~ tl~oi~gl~ :I sndur at sea might not be bothered by sea clutter., rie:tr~t,y  land clutter can be so large that it can enter the radar via the antenna sidelobes and degrade  performance. 
 ECHO ANALYSIS IS USED TO EVALUATE THE EFFECT OF AMPLITUDE AND PHASE DISTORTION ON THE TIME SIDELOBE LEVELS &REQUENCY DOMAIN AMPLITUDE AND PHASE DIS 
 163–168. 90. I. 
 14 INTRODUCTION TO RADAR SYSTEMS  REFERENCES  1. Guerlac, H. E.: "OSRD Long History," vol. 
 DIMENSIONAL  POINT 
 An effective suboptimal solution is the Auction  algorithm, which views the tracks as being “auctioned off” to the detections—   iteratively assigning higher costs to tracks competed for by more detections.60   Figure 7.33 provides a comparison61 of the Munkres, JVC, and Auction algorithms  optimized for sparse data. The JVC and Auction algorithms provide a significant  increase in computational speed. Although the Auction algorithm is simpler, requir - ing less lines of code, the JVC algorithm generally requires less computation time. 
 January, 1973.  104. Glover, K. 
 02& 2ANGE 
      "Y  APPLYING %QS  AND  TO THE SIMPLE CASE OF ONE AUXILIARY ANTENNA AND ONE  JAMMER  THE FOLLOWING RESULTS ARE FOUND   }[ ] [\ \] \ \7 
 TION !PPLICATION TO THE INTERPRETATION  OF METEOR BACKSCATTER A T MEDIUM FREQUENCY v  * 'EOPHYS  2ES  VOL !  PP     4 * %LKINS  h!  MODEL FOR HIGH FREQUENCY RADAR AURORAL CLUTTER v 2!$# 2EPT 42 
 Contours for fixed values of time delay are shown in Fig. 11.9b. The center contour corre-  sponding to TR = 0 is the spectrum of a rectangular pulse [Eq. 
 (2.17) is equal to J(4/n) - l times the  mean value. and for the exponential density of Eq. (2.18) the standard deviation is equal to w0. 
  
 (STC is also sometimes employed  in radar not bothered by clutter to make more uniform the target echo power with range.)  Another technique for reducing saturation is instantaneous automatic gain control (IAGC)  based on negative feedback controlling the gain of the IF amplifier. The response time of the  IAGC is adjusted so that echo pulses from point targets pass with little attenuation, but longer  pulses such as those from extended clutter are attenuated. That is, the automatic gain control  is made to act within the time of a few pulse widths: The IAGC acts something like a  pulse-width filter, permitting target pulses to pass and attenuating the longer pulses from . 
 The concept of searchlighting and lobe switching is illus- trated in Fig. 20. Ic. 
 In general, this is the paramount limitation since the noise floor of the phase detection circuitry is usually well below that of the internal or, for that matter, the external reference sources. This assumes that the AM noise on both sources used in the test is well below the phase-modulation noise. The only safe course is first to measure the AM noise on any unknown source with a simple amplitude detector available with the instrumentation. 
 This discussion will follow the analysis performed by  Allen. As previously mentioned, amplitude and phase errors take a fraction of the  energy from the main beam and distribute this energy to the sidelobes. This fraction  is, for small independent random errors,  σ σ σφ T A2 2 2= +   where sf = rms phase error, rad  sA = rms amplitude error, volts/volt (V/V) This energy is radiated into the far field with the gain of the element pattern. 
   . 
 Geosci. Remote Sens. 1985 ,1, 47–56. 
  .   4(% 2!$!2 42!.3-)44%2   £ä°Ç HIGH 
 DOMINANTLY BY THE ARRAY GEOMETRY 3ECTION    THE RADIATING ELEMENT MAY BE CHOSEN TO SUIT THE FEED SYSTEM AND THE PHYSICAL REQUIREMENTS OF THE ANTENNA &OR EXAMPLE  IF THE RADIATOR IS FED FROM A STRIPLINE PHASE SHIFTER  A STRIPLINE DIPOLE WOULD BE A LOGICAL CHOICE )F A WAVEGUIDE PHASE SHIFTER IS USED  AN OPEN 
 2ADAR  3ONAR .AVIG  VOL   NO   *UNE   ( $ 'RIFFITHS AND . 2 7 ,ONG  h4ELEVISION 
 Protection must be provided  against overload or saturation, and burnout from nearby interfering transmitters. Timing and  CHAPTER NINE RECEIVERS, DISPLAYS, ANDDUPLEXERS 9.1THERADAR RECEIVER Thefunction oftheradarreceiver istodetectdesiredechosignalsinthepresence ofnoise, interference. orclutter.Itmustseparate wantedfromunwanted signals,andamplify the wantedsignalstoalevelwheretargetinformation canbedisplayed toanoperator orusedin anautomatic dataprocessor. 
 ACTERISTIC SPECIFIED FOR A RADAR RECEIVER  YET FEW RADARS EMPLOY THE LOWEST 
 For example, when presented with the requirement  to track 20 targets, the designer may not realize that radar returns from the 20 targets of  interest may be embedded in similar returns from thousands of unwanted targets. A typical long-range air-traffic-control radar has sufficient sensitivity to detect a  single large bird, such as a crow, seagull, or vulture (approximate RCS of 0.01 square  meter) at a range of 50 miles. If there are many such birds in the resolution cell of the  radar, then the composite RCS increases. 
 FED REFLECTOR AS THE FEED IS MOVED OFF 
 127. G. Zhang, J. 
 A radar that can detect a 1 m2 target at 200 nmi can detect a 10-4 m2  target at 20 nmi because of the inverse fourth power variation of signal strength with range.  Therefore. small nearby targets such as birds and insects can clutter the output of a radar. 
 Correction of the data may still  270INTRODUCTION TORADAR SYSTEMS talvalueswere l~ssthanpredicted bytheQrysincetilewaterwasnotauniform film,but formedmanysmallstreaksthatrapidlyranofftheradome innarrowrivulets. Theperformance ofareflector withouttheprotection ofaradomecanalsobedegraded byrain.Theeffectissmall,however, atfrequencies belowXband.Waterimpinging onthe antenna feedcanhaveseriouseffects.Thewettingofsurfaces through whichsignalsare transmitted shouldbeavoided. Also,adequate drainage shouldbeprovided topreventthe accumulation ofwaterinthereflector. 
 Inboth cases theamplifier consists ofasingle tube onwhose grid the original signal isformed. The entire plate swing isapplied tothe condenser, sothat thefeedback ratio is1.Inthe case of suppressor switching, allofthecurrent goes tothescreen between sweeps. The control grid isheld against the cathode byvirtue ofitspositive bias. 
 (a) Uniform amplitude weights and (h) 25-dB Chebyshev weights. The average  improvement for all filters is indicated hy the dotted curve. (From Andrews.30) . 
 TO 
 For comparison, the improvement factor for an  N-pulse canceler is shown in Fig. 4.25. Note that the improvement factor of a two-pulse  canceler is almost as good as that of the 8-pulse doppler-filter bank. 
 10.14). The above reasoning suggests that, under theinfluence ofther-ffields, theelectrons inthis space charge which are inanaccelerating r-ffield travel back toward thecathode, while those in adecelerating r-ffield travel toward theanode. The result may beseen from Fig. 
 CONTROLLED TUBE KNOWN AS AN  )NDUCTIVE /UTPUT 4UBE    OR )/4 4HE #%! IS SIMILAR TO SOMETHING CALLED A +LYSTRODE  EXCEPT THAT THE #%!  EMPLOYS THE )/4 WITH A MULTISTAGE DEPRESSED COLLECTOR SIMILAR TO THAT USED IN KLYS 
 DETECTOR 
 LEVEL  RESTRAINTS MOTIVATED A SUPERB INNOVATIVE RADAR DESIGN #OST 4HERE WERE SEVERAL CONSEQUENCES TO THE SEVERE REDUCTION IN APPROVED  FUNDS RELATIVE TO FUNDS REQUESTED FOR THE ORIGINAL 6ENUS /RBITING )MAGING 2ADAR  6/)2  MISSION 2ATHER THAN A CONVENTIONAL CIRCULAR ORBIT   -AGELLAN WAS REDESIGNED  FOR AN ELLIPTICAL ORBIT &IGURE    WHICH HAD CONSIDERABLY LESS ASSOCIATED COSTS AND RISK !LSO  RATHER THAN THE ORIGINAL LARGE HIGH 
 BIGUOUS 02& OF  (Z FOR A 5(& RADAR 4HIS FIGURE HIGHLIGHTS  THAT EVEN WITH DOP 
 The platforms for such radars include satellites as well as aircraft.  La~v Erfircentenr. In addition to the wide use of radar to measure the speed of automobile  traffic by highway police, radar has also been employed as a means for the detection of  intruders. 
 The target signal in the auxiliary array that may result in nonnegligible steering of  the auxiliaries toward the main-beam direction  9. Multipath delay, often expressed in terms of delay-bandwidth product69–70 10. The presence of clutter that, if not properly removed, may capture the adaptive sys - tem, giving rise to nulls along directions different from those of the jammers37,71 11. 
 R. H. Delano, “A theory of target glint or angle scintillation in radar tracking,” Proc. 
 At first the  name is some what misleading.  It signifies the possibility to already determine the target with  one pulse.  As almost always there are, as normal, a vast number of pulses to integrate for i m- proving the signal- to-noise ratio. 
 Themodulator produces the synchronizing signals that trigger the transmitter the required number of times per second. It also triggers theindicator sweep and coordinates the other associated circuits. Thetransmitter generates the radio-frequency energy in the form of short powerful pulses. 
 CESSOR ARE OFTEN FITTED IN MINIMALLY ENCLOSED AREAS AND ARE SUBJECT TO VERY DAMP AND SALTY CONDITIONS )N THESE ENVIRONMENTS  THE RADAR HAS TO DETECT TARGETS THAT CAN HAVE ECHOING AREAS RANGING FROM LESS THAN ONE SQUARE METER TO MANY TENS OF THOUSANDS OF SQUARE METERS IMPORTANT TARGETS CAN HAVE RELATIVE SPEEDS RANGING FROM STATIONARY TO  KNOTS OR MORE THE TARGETS CAN BE SITUATED IN EXTREME PRECIPITATION AND SEA CLUTTER CONDITIONS AND THE RADAR ANTENNA IS NOT MOUNTED ON A STATIC NOR A STABLE PLATFORM 4HE RADAR IS USED TO PREVENT COLLISIONS AND GROUNDINGS AT SEA AND IS  THEREFORE  AN IMPORTANT SAFETY RELATED SYSTEM  REQUIRING INTEGRITY AND RELIABILITY &OR MOST COMMERCIAL SHIPS  THE RADAR NEEDS TO MEET STRINGENT  INTERNATIONALLY AGREED PERFORMANCE CRITERIA $ESPITE THESE REQUIREMENTS  SYSTEMS ARE SOLD IN A HIGHLY COMPETITIVE MARKET AND PRICES ARE  THEREFORE  KEPT KEEN 0RICES RANGE FROM AROUND   FOR A COMPLETE BUT BASIC  '(Z SYSTEM TO   AND ABOVE FOR A FULLY FEATURED  '(Z SYSTEM  2ADAR SYSTEMS SUIT 
 vol. AP-5. pp. 
 65, pp. 551–562, 1970. 60. 
 115. T. A. 
 This  limitation applies even though the system uses limiting before the canceler because  there is always much clutter present that does not reach the limit level. With most  transmitters, however, the amplitude jitter is insignificant after the frequency-stability  or phase-stability requirements have been met. Jitter in the sampling time in the A/D converter also limits MTI performance. 
 This detector incurs a CFAR loss of about 2 dB but achieves a fixed Pfa for any unknown noise density as long as the time samples are independent. This detector was incorporated into the ARTS-3A postprocessor used in conjunction with the Federal Aviation Administration airport surveillance radar (ASR). The major shortcoming of this detector is that it is fairly susceptible to target suppres- sion (e.g., if a large target is in the reference cells, the test cell cannot receive the highest ranks). 
 TION OF %GYPTIAN AND .ORTH !MERICAN )NDIAN SITES AS WELL AS CASTLES AND MONASTERIES  IN %UROPE 4HE QUALITY OF THE RADAR IMAGE CAN BE EXCEPTIONALLY GOOD  ALTHOUGH CORRECT UNDERSTANDING NORMALLY REQUIRES JOINT INTERPRETATION BY THE ARCHAEOLOGISTS AND RADAR SPECIALISTS 3INCE   THE 3QUARE 'EOPHYSICAL 3URVEY 0ROJECT  UNDER THE AUSPICES OF THE .ATIONAL -USEUM OF 3COTLAND AND THE 'LASGOW -USEUMS  HAVE BEEN CARRYING OUT GEOPHYSICAL AND ARCHAEOLOGICAL SURVEYS AT 3QUARE IN %GYPT 3QUARE FORMS PART OF THE NECROPOLIS OF THE ANCIENT %GYPTIAN CAPITAL CITY OF -EMPHIS 4HE BURIAL GROUNDS EXTEND FROM !BU 2OASH  JUST TO THE NORTH OF #AIRO  SOUTHWARD THROUGH 'IZA  !BUSIR  3AQQARA  AND $AHSHUR TO -EIDUM APPROXIMATELY  KM TO THE SOUTH 4HE FAMOUS 3TEP 0YRAMID OF THE RD $YNASTY RULER  +ING :OSER   DOMINATES THE SITE OF 3AQQAR A 4HE MAIN MONUMENT  IS KNOWN AS THE 'ISR EL 
 It was noted, 30 however, that the propaga­ tion of electromagnetic energy from antennas well below the duct is greater than would be  predicted from classical ray theory. One explanation postulated for explaining this  discrepancy is that energy can be scattered into and out of the elevated duct by irregularities in  the index-of-refract ion profile.  E,·aporation duct. 
 In looking at the per- formance index curves with radar range as the independent variable,• = R4fh Loss. = R4fh + L ° = Frequency* = El. Angle ^ 1 deg.« = NoiseLoss (dB) Noise (dBW)Frequency (MHz) or El. 
 Athigh altitude, low temperatures and airdensities areencountered. The low temperature tends tolower the speed byreducing the resistance ofthe motor field circuit, whereas low airdensity allows the speed LOincrease because oflower windage losses. The following test data indicate the conditions formaximum and mini- mum frequency ofthe 1500-va PE-218-C and PE-218-D inverters.. 
 37. Boyd. C. 
 A. Fabrizio, “Space-time characterization and adaptive processing of ionospherically-propa - gated HF signals,” Ph.D. dissertation, Adelaide University, Australia, July 2000. 
 1.26Thesearecallednlllitimode feeds.Theuseofhigher-order waveguide modesinmonopulse feedstogenerate therequired patterns resultsinfeedsthatan: ofhighefficiency, compact, simple,lowloss,lightweight,lowaperture blockage, andexcellent boresight stability independent offrequency. Thegreaterthesignal-to-noise ratioandthesteepertheslopeoftheerrorsignalinthe vicinityofzeroangularerror,themoreaccurate isthemeasurement ofangle.Theerror-signal slopeasafunction ofthesquintangleorbeamcrossover isshowninFig.5.11.Themaximum slopeoccursatabeamcrossover ofabout1.1dB. Automatic gaincontrol(AGC)isrequired inordertomaintain astableclosed-loop servo systemforangletracking. 
 The parameter C/L is the ratio of the rms clutter power to the receiver-IF  limit level.  The loss of improvement factor increases with increasing complexity of the canceler.  Limiting in ·the three-pulse canceler will cause a 15 to 25 dB reduction in the performance  predicted by linear theory.50 A four-pulse canceler (not shown) with limiting is typically only  2 dB better than the three-pulse canceler in the presence of limiting clutter and offers little  advantage. 
 TIONAL PARAMETERS OF HIGH 
 VERTICAL ERROR IN MEASURING  THE SCATTERING COEFFICIENT . 
 Sensors 2019 ,19, 516     ( a )  B c o s ș as a function of altitude.      (b) Electron density profile.     (c) Bcos ș as a function of TEC  Figure 3. 
 The antenna assembly, includ- ingthemount that supports itand makes itmove, iscalled a”mechanical seamer. ”The t6rm “electrical scanner” isreserved forcases where the beam ismoved notbyamotion oftheantenna asawhole, but rather by relatively subtle motions ofthefeed orother parts oftheantenna. The borderline between mechanical and electrical scanning isnotwell defined. 
 The three-dimensional result for an edge of fi- nite length € may be obtained by inserting Eqs. (11.22) and (11.23) in Eq. (11.21), using Eq. 
 way power pattern of interest with the gaussian approximation at a specific point on the pattern, determining the standard deviation of 6 by using statistical tech- niques, or fitting the pattern and using numerical methods. The calculation of the improvement factor / can be performed by averaging the resultant residue power, obtained by summing the signal phasors at specific values of 9, from null to null of the antenna pattern. Figure 16.8 shows the effect of platform motion on the MTI improvement fac- tor as a function of the fraction of the aperture displaced in the plane of the ap- erture per interpulse period Tp. 
       " !    # ,*+ (-,() ,*+ (-,()  /6 (-,()  8 /6 (-,()  /6 (-,()     2(15(.&7(',$. '           
 The simple modulator is scarcely less complex than the balanced modulator and requires a sharper filter for the necessary added carrier suppression. Phase lock- ing eliminates the need for high-frequency filtering altogether but requires a skillfully designed servo loop to impress the transmitter's FM noise faithfully on the local os- cillator. It may also require a search mechanism to pull in initially. 
 ART FOR TRANSISTOR PERFORMANCE IS DEFINED ON SEVERAL FRONTS IN THE SEMICONDUCTOR INDUSTRY BY THE FOLLOWING PERFORMANCES   PULSED POWER 
 STATE AMPLIFIERS 4HE POWER OUTPUT LEVEL FROM A PARTICULAR DEVICE IS A FUNCTION OF NOT ONLY THE CHOSEN  TECHNOLOGY  BUT ALSO  THE FREQUENCY AND OTHER CONDITIONS  SUCH  AS PULSE WIDTH  DUTY CYCLE  AMBIENT TEMPERATURE  OPERATING VOLTAGE  AND THE PRESENTED LOAD IMPEDANCE 4ECHNOLOGIES AND #ONSTRUCTION  3EMICONDUCTING MATERIALS USED IN THE FABRI 
 But so is a bowl of soup or a tank of water or a rushing  stream—all of which might share certain behaviors with a sea surface, while pre - senting a venue much more amenable to the comfortable investigation of scattering  phenomenology. While there is the obvious matter of scale , one might entertain the  notion that what is found to hold in the small compass of a laboratory wave tank might  transfer with little alteration to the open ocean. But this certainly cannot be true; the  sea surface is structured by large-scale wind systems, impossible to duplicate under  laboratory conditions. 
 An  additional 10 dB of isolatiorl might be obtained.12 The phase and amplitude of the leakage  signal, however, can vary as the antenna scans, which results in varying cancellation. There-  fore. when additional isolation is necessary, as in the high-power CW tracker-illuminator, a  ~I~II;III~~C C;IIICCIC~ L';\II t>e IISC~ tli;~t SCI~SCS the proper phase r71icI arnplittrdc required or the  nulling ~ignal.~.' Ilynarnic carlcelalion of the leakage by this type of " feedthrough nullirlg"  ca rl exceed 30 i3,3 '  'I'lie traris~liiltcr signal is never a pure CW waveform. 
 SCALE BREAKING WAVES DISPLAY TWO CHARACTERISTIC BEHAVIORS SPILLING  IN WHICH AN UNSTABLE WAVE PEAK UNRAVELS  AND  PLUNGING  WHERE THE PEAK CURLS  OVER ON ITSELF AND CRASHES ONTO THE FRONT FACE AS A CASCADE OF WATER MASSES  ENDING IN A CHAOTIC JUMBLE  !NOTHER DIFFERENT EVENT IS THE  MICROBREAKER  A SMALL  TRANSIENT SHOCK  FRONT INDUCED BY A PUFF OF WIND OR ANOTHER WAVE !S NOTED EARLIER  HIGHLY AVERAGED WAVE SPECTRA CANNOT DISCLOSE THE MORPHOLOGY OF SUCH SURFACE FEATURES  AND  UNFORTUNATELY  PHYSICAL OCEANOGRAPHY IS STILL UNABLE TO PROVIDE A GENERALLY SATISFACTORY DESCRIPTION OR CHARACTERIZATION OF WAVE BREAKING  .EVERTHELESS  THERE ARE TWO USEFUL HEURISTIC PARAM 
 Obviously, thereceiver shouldbe designed togenerate aslittleinternalnoiseaspossible, especially intheinputstageswherethe desiredsignalsareweakest. Although specialattention mustbepaidtominimize thenoiseof theinputstages,thelowestnoisereceivers arenotalwaysdesiredinmanyradarapplications if otherimportant receiverproperties mustbesacrificed. Receiver designalsomustbeconcerned withachieving sufficient gain,phase,andampli­ tudestability, dynamic range,tuning,ruggedness, andsimplicity. 
 610 2. 3. F,-EXAMPLES OF RADAR SYSTEM DESIGN [SEC. 
 In these cases, transmit and receive beams become more closely aligned in a  ch23.indd   26 12/20/07   2:21:43 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 
 Con~pulse~~ and "scan with compensation "" are the names given to  a hybrid tracking system that is a combination of monopulse and conical scan. Two squinted  beams, similar to those of a single angle-coordinate amplitude-comparison monopulse, are  scanned (rotated or nutated) in space around the boresight axis. (In the conical scan tracker,  only one squinted beam is scanned.) In conopulse, the sum and difference signals received in  the two squinted beams are extracted in a manner similar to that of the conventional monopulse  system. 
 K.: Trade-off Between Picture Element Dimensions and Non-Coherent Avrrag~ng In  Side-Looking Airborne Radar, IEEE Trans., vol. AES-15,, pp. 697-708, September, 1979. 
 20.70  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 section for hybrid multipath, Faraday rotation, and differential Faraday rotation—are  incorporated via parametric models derived from measurements or computational  electromagnetics and the distribution obtained by Monte Carlo simulation. APPENDIX: HF SURFACE WAVE RADAR General Characteristics and Capabilities.  Although skywave propagation  provides the unique capability of low altitude target detection at ranges of thousands  of kilometers, other forms of propagation at HF can be exploited in radar applications. 
 Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 11.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 30. G. 
 In addition to the default height versus range display, AREPS contains many other  display and data output options. For example, Figure 26.17 shows (for the same missile  detection example) a signal-to-noise ratio versus range display superimposed with a clutter-   to-noise ratio computed from an 8 meter-per-second wind speed. The display altitude is  100 feet above sea-level. 
 39-42, November, 1975. ·  26. Easton, R. 
 Thus the radar antenna is called upon to fulfill reciprocal but related roles. In  the radar equation derived in Chap. 1 [Eq. 
 S. V.: Planar Array Looks Through Lens to Provide Hemispherical Coverage, Microwat~es.  vol. 
    WHERE  F  IS THE RATIO OF THE INTERVALS 4HE APPAR 
 28 INTRODUCTION TO RADAR SYSTEMS  4 6 8 " 10 12 14 16 18 20  (S/N ), , signal-to-noise ratio, dB  Figure 2.7 Probability of detection for a sine wave in noise as a function of the signal-to-noise (power)  ratio and the probability of false alarm. .I  Both the false-alarm time and the detection probability are specified by the system require-  ments. The radar designer computes the probability of the false alarm and from Fig. 
 Many factors contribute to the selection of the orbit to be used for each type of SBR and particularly for a large surveillance-type SBR. The orbit parameters of period, altitude, and velocity are the first consideration. The velocity for a satellite in a circular orbit around the earth is given by16 Vc - ^ (22.D where r is the distance of the satellite from the center of the earth and u, is the product of the universal gravitational constant and the mass of the earth. 
 This bending usually results in an increase in the radar line of sight. Normal  atmospheric conditions can be accounted for in a relatively simple manner by considering the  earth to have a larger radius than actual. A "typical" earth radius for refractive effects IS  four-thirds the actual radius. 
 HALF OF THE RADAR WAVELENGTH  WITH ONE SOLUTION CORRESPONDING TO A WAVE DIRECTLY APPROACHING THE RADAR AND THE OTHER RECEDING FROM IT 4HE CORRE 
 Application lo measurement of sea conditions. The distinctive nature of the doppler frequency  shill from the sea allows information to be extracted regarding the· sea conditions and the  wm,ls driving the sea.i4·25 The major portion of the doppler-frequency spectrum from th.: <;ca . SJ4 lNTRODUCTlON TO RADAR SYSTEMS  o---- 10 ---------+--·--+------+-- 4i  l 20 a. 
 However, modern processors permit affordable thresholding algorithms of consider - able complexity. Manufacturers keep their own processes highly confidential because  of the effort that has gone into their empirical optimization. Theoretical clutter models  have been generally found unsuitable to be used for optimization. 
 Equation (2.4a)mayberewritten as (2.4b) Thenoisefiguremaybeinterpreted, therefore, asameasure ofthedegradation ofsignal-to­ noise-ratio asthesignalpassesthrough thereceiver. Rearranging Eq.(2.4").theinputsignalmaybeexpressed as (2.5) Iftheminimum detectable signal SmlnisthatvalueofSIcorresponding totheminimum ratioof output(IF)signal-to-noise ratio(So/No~lnnecessary fordetection. then (2.6) Substituting Eq.(2.6)intoEq.(2.t)resultsinthefollowing formoftheradarequation: (2.7) Beforecontinuing thediscussion ofthefactorsinvolved intheradarequation. 
 70. Maguire, W.W.: Application of Pulsed Doppler Radar to Airborne Radar Systems, Proc. Nari. 
 JPFS  3IGNAL TIME SHIFT   XT EXPJPFT  8  F  
 In the quantum-mechanical case, on the other hand, the observer does not  have controlrover his system as does the radar designer since'the Pa product of a quantum  particle is fixed by nature and not by the observer.  Angular accuracy. The measurement of angular position is the measurement of the angle of  arrival of the equiphase wavefront of the echo signal. 
 Sherwin, J. P. Ruina, and R. 
 in 1998 [ 23]. Authors used it in classifying digits, and it was applied by several banks to recognize hand-written numbers. The pixels of images were 32 ×32. 
 L. Fante, “Cancellation of specular and diffuse jammer multipath using a hybrid adaptive  array,” IEEE Trans ., vol. AES–27, no. 
 BAND  UNFILTERABLE MIXER PRODUCTS  OR LEAKAGE DUE TO INSUFFICIENT ISOLATION BETWEEN SIGNAL SOURCES WITHIN A RECEIVER OR EXCITER )N ADDITION TO EXTERNAL SOURCES OF INTERFERENCE  THE RADAR DESIGNER &)'52%  #LUTTER RESIDUE DUE TO ,/ PHASE NOISE  ( $ (  ) ' $,#$#+ '( $# ' &* #-. 
 A theta-thcta location technique uses the angles 6r and QR and an estimate of L, where 9r is typically provided by a monostatic radar, which acts as a cooperative bistatic transmitter. For an elliptic location system, target location errors typically increase as the target approaches the baseline, ignoring S/N changes. The principal source of er- rors is the geometry inherent in Eq. 
 BEAM TARGET COMPETES WITH BOTH MAIN 
 The second modulation might be a  linear frequency modulation which increases, rather than decreases, in frequency. This is  analogous to the FM-CW radar of Chap. 3, in which the doppler frequency shift is extracted as  well as the range. 
 ,I The effective radiation pattern of the radar located at A in Fig. 12.1 may be found in a  manner analogous to that of a two-element interferometer antenna formed by the radar  antenna at A and its image mirrored by the ground at A'. The difference between the reflected  path AMB and the direct path AB (or AUMB) is A = 2ha sin c, when R % ha. 
 The third simple motion ofthe beam isconical scan, inwhich the path described onthe sphere isacircle ofavery few degrees diameter. This scan isnot used forsearch, but finds wide useinaccurate tracking ofan individual target (see Sec. 6.14). 
 This can be demonstrated both experimentally and theoretically.37,38 A pair  of scatterers can be appropriately spaced to cause a tracking radar with closed-loop  tracking to align its antenna axis at a point many times the scatterer spacing away  from the scatterers. If the scatterers are stationary, the radar antenna will stay pointing  in the erroneous direction. Figure 9.20 shows experimental data demonstrating this  phenomenon with a two-reflector target. 
 SAFE REAL 
  D" SIDELOBES  A 4AYLOR ILLUMINATION  THAT PROVIDES  
 Thus successive I-ysec pulses, adjacent intime, appear atthe grids ofV8band VE~respectively. Their boundary time ismade coinci- dent with the mean time ofarrival ofthe azimuth pulse byadjustment ofthe slope ofthe sawtooth inthe delay circuit. The amplified pulse train from point X(plate ofVti)ofFig. 
 We may simplify the problem by assuming a rectangular illuminated area, R<bQ by cr/(2 sin 6). Fur- thermore, the curvature of the isodops may be neglected, and so the doppler fre-FIG. 12.7 Contours of constant doppler fre- quency shift on a plane earth due to horizon- tal motion.FIG. 
 Hence, there will be variation in the velocity of propa - gation with frequency. Dielectrics exhibiting this phenomenon are termed dispersive.   In this situation, the different frequency components within a broadband radar pulse would  travel at slightly different speeds, causing the pulse shape to change with time. 
 In contrast to airborne systems, the dynamics of most spacecraft are such that no  motion compensation is required for space-based SARs (unless extremely fine resolu - tion is to be generated). However, determining the doppler centroid of the azimuth  spectrum with respect to zero doppler emerges as a dominant issue. If the azimuth  antenna boresight is perfectly orthogonal to the inertial orbit plane, the Earth’s rota - tion imposes a doppler shift onto the received data.30 From low Earth orbit (LEO), the  magnitude of this shift is on the order of 3 °, and (to first order) varies sinusoidally  with latitude, with maximum magnitude at the equator, and with zero at the extreme  N and S latitudes. 
 However, even small errors of this magnitude  will cause significant errors in multilateration systems that determine target angle by  calculations using precise range measurements from separate locations. 9.10 INTERNAL SOURCES OF ERROR Receiver Thermal Noise.  The angle error caused by receiver thermal noise in a  monopulse tracking system is  σθ τ βtB m r n k B S N f= ( ) ( )/ / (9.10) where km is the angle-error-detector slope. 
 In each stage, the Q (or I) input is divided by a fac - tor of 2i by shifting the number to the right by i bits, and then added to or subtracted  from the I (or Q) input, depending on the sign of f. The variable i is incremented and  the process repeats until i > N, at which point the phase-shifted results are available. Figure 25.29 is a block diagram of an eight-stage CORDIC processor that imple - ments a phase shift, where each stage represents an iteration in the flow chart. 
 It is not surprising that the achievement of all these properties  cannot always be fully satisfied simultaneously. Antenna design is an important part of the  successful realization of a good monopulse radar.  The uniform aperture illumination maximizes the aperture efficiency and, hence, the  directive gain. 
 DOMAIN WEIGHTING  AND SPECTRAL ANALYSIS USING AN &&4 PADDED WITH ZEROS  0REVIOUS IMPLE 
 Phillips, “F-15 ESA medium PRF design,” Hughes Aircraft  IDC No. 2312.20/804, January 9, 1987, unclassified report. 34. 
 A., and R. T. Moller: The Effect of Normally Distributed, Random Phase Er- rors on Synthetic Array Gain Patterns, IRE Trans., vol. 
 STATE INPUT VALUE  4HIS IS  DONE BY CHANGING THE CANCELER GAINS SO THAT ALL DELAY LINES ACHIEVE THEIR STEADY 
 4ARGET 3URFACES  3OMETIMES CLUTTER HAS INTERNAL MOTION 4HIS CAN OCCUR  WHEN FIXED RADARS ARE USED TO OBSERVE MOVEMENT OF THE SEA AND THE LAND /N LAND  CLUTTER MOTION IS USUALLY DUE TO MOVING VEGETATION  ALTHOUGH MOVING ANIMALS AND MACHINES CREATE SIMILAR EFFECTS 4HE RADAR RETURN FROM AN ASSEMBLY OF SCATTERERS LIKE THOSE SHOWN IN &IGURE  CAN CHANGE BECAUSE OF MOTION OF THE  INDIVIDUAL SCATTERERS  JUST AS IT CHANGES BECAUSE OF MOTION OF THE RADAR 4HUS  IF EACH SCATTERER IS A TREE  THE WAVING OF THE TREES AS THE WIND BLOWS CAUSES RELATIVE PHASE SHIFTS BETWEEN THE SEPARATE SCATTERERS THE RESULT IS FADING &OR A FIXED RADAR  THIS MAY BE THE ONLY FADING OBSERVED  EXCEPT FOR VERY SLOW FADING DUE TO CHANGES IN REFRACTION )F THE SURFACE ELEMENTS ARE STIFF  THEY MAY NOT MOVE ENOUGH TO GET SIGNIFICANT DOPPLER SPREADING  AND THE FADING  DISTRIBUTION MAY NOT BE CLOSE TO 2AYLEIGH 3EE "ILLINGSLEY  AND OTHER PAPERS BY HIM  FOR MORE DISCUSSION OF THE SITUATION FOR FIXED RADARS OBSERVING GROUND TARGETS &OR A  MOVING RADAR  THIS MOTION OF THE TARGET CHANGES THE RELATIVE VELOCITIES BETWEEN TARGET ELEMENT AND RADAR SO THAT THE SPECTRUM IS DIFFERENT FROM THAT FOR A FIXED SURFACE 4HE WIDTH OF THE SPECTRUM DUE TO VEHICLE MOTION DETERMINES THE ABILITY OF THE RADAR TO DETECT THIS TARGET MOTION £È°xÊ 
 b THEMAPLEPRESSCOMPANY,YORK,PA.. RADAR SYSTEM ENGINEERING EDITORIAL STAFF LouIs N.RIDENOUR AVIS M.CLARKE CONTRIBUTING AUTHORS L.Y.BEERS B.Y.BOWDEN W.M.C.4DY R.E.CLAPP C,.B.COLLINS A.G.EMSLIE W.W.HANSEN L.J.HAWORTH R.G.HERB M.M.HUBBARD P.C.JACOBS M.H.JOHNSON W.H.JORDAN J.V.LEBACQZ F.B.LIXCOLX R.A.MCCONNELLF.J.MEHRINGER R.D.O’XEAL C.F.J.OVERH.WE E.C.POLLARD E.M.PURCELL L.N.RIDENOUR C.V.ROBINSON A.J.F.SIEGERT R.L.SIIWHEIMER D.C.SOPER G.F.TAPE L.A.TURNER M.G.WHITE A.E.WHITFORD J.M.WOLF C.L.ZIMIERMAN. Foreword THEtremendous research and development effort that went into the development ofradar and related techniques during World War II resulted not only inhundreds ofradar sets formilitary (and some for possible peacetime) usebut also inagreat body ofinformation and new techniques inthe electronics and high-frequency fields. 
 The fundame n- tal idea is to add a reciprocal ripple filter in series with the phase -only matched filter, such that  spectral ripple in the signal is cancell ed, as represented in Figure 12.26. The gray curve shows  the signal spectrum and the black curve is the combined response of the Bessel filter and r e- ciprocal ripple filter. It can be seen that the total filter response exactly counters the residual  spectra l ripple with the result that the signal spectrum at its output has a smooth chara cteristic  as shown in Figure 12.27. 
 Task 1 would require only  short CITs, 1–2 s, say, if the aircraft is assumed to be large, and would need revisits  perhaps every minute, as the flight is not expected to maneuver so the track will be  well-behaved and observed position errors would be due to ionospheric fluctuations.  Only the single DIR containing the aircraft need be interrogated. Task 2, barrier sur - veillance, if concerned with ship traffic, can afford to relax the revisit time to tens  of minutes as ships move so slowly, but in order to achieve detection, long CITs of  20–30 s are required to separate the ship echoes from the sea clutter in the doppler  spectrum. 
 $/7 $OPPLER ON 7HEELS  IS A MOBILE 8 
 )  6OL   !RTECH (OUSE  )NC  .ORWOOD  -!    PP n  2 3 2AVEN  #ORRECTION TO h2EQUIREMENTS FOR MASTER OSCILLATORS FOR COHERENT RADAR v IN  0ROCEEDINGS  OF THE )%%%  VOL   ISSUE   !UGUST   P . {°xÓ  2!$!2 (!.$"//+   - 'RAY  & (UTCHINSON  $ 2IDGELY  & &RUGE  AND $ #OOKE  h3TABILITY MEASUREMENT PROBLEMS  AND TECHNIQUES FOR OPERATIONAL AIRBORNE PULSE DOPPLER RADAR v  )%%% 4RANSACTIONS ON !EROSPACE  AND %LECTRONIC 3YSTEMS  VOL !%3 
 A common method of frequency measurement is to use a scanning superhetero - dyne receiver that has the advantage of high sensitivity, good frequency resolution,  and immunity with respect to the interference of nearby emitters.9 Unfortunately,  this type of receiver has a poor probability of intercept for the same reasons as the  rotating bearing measurement system. The situation is much worse if the emitter is  also frequency-agile (random variation) or frequency-hopping (systematic varia - tion). A common method to allow for wideband frequency measurements is based  on interferometric devices that provide instantaneous frequency measurement with  good accuracy and are able to reject signal interference with lower intensity. 
 WAY RADAR SIGNAL PATH  CAUSES A FULL  CHANGE IN RELATIVE PHASE !T 8 BAND  THIS IS ABOUT  CM  WHICH IS SMALL EVEN COMPARED WITH THE FLEXURE BETWEEN PARTS OF AN AIRCRAFT 4HE FIVE TYPES OF MODULATION CAUSED BY A COMPLEX TARGET ARE DISCUSSED NEXT !MPLITUDE .OISE  !MPLITUDE NOISE IS THE CHANGE IN ECHO SIGNAL AMPLITUDE CAUSED  BY A COMPLEX 
 6, pp. 1211-1220, Nov. 1.1957. 
 CAUSED RANGE 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 4.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 The system-level CW phase noise floor requirement ( −121.6 dBc/Hz) is allocated  to the contributing hardware units. 
 GTD and PTD are both based on the exact solution of the two-dimensional wedge problem, for which the directions of incidence and scattering are perpen- dicular to the edge. When extended to the case of oblique incidence, the direction of observation must lie along a generator of the Keller cone depicted in Fig. 11.26. 
 Typical vortex models which are qualiﬁed include the Rankine vortex [ 17], Oseen vortex [ 18], Burgers-Rott vortex [ 19–22], and Sullivan vortex [ 23]. The Rankine vortex model assumes that the vorticity of its core is discontinuous, which is not the case for shear-wave-generated eddies. The Oseen vortex model is hypothesized to be a plane ﬂow; however, shear-wave-generated eddies should be three-dimensional. 
 (31)into Eq. (30) will give thereceived signal S. Atmedium and long ranges (compared tothealtitude oftheairplane), the factor sec8isapproximately unity and can beneglected. 
 The Radar horizon is given by the  Earth’s curvature and the height of the Radar equipment & the target object, as shown in Figure  3.3.    Figu re 3.3  Location determination of an object under the horizon (RE = Earth’s radius)   Considering the geometry & optics, the following estimation for the range of coverage is yielded  by:  € Rgeom=R1+R2=(hT+RE)2−RE2+(h0+RE)2−RE2 ≈2hTRE+2h0RE=2RE⋅hT+h0 ( ) (3.13)  This estimation is derived under the fol lowing requirements:   -  € RE>>hT,h0  - Earth is flat and void of various elevations   - Refraction of the electromagnetic waves in the atmosphere is neglected   This estimation of the neglect of the refraction leads to an under -estimation of the rang e of cover- age.  While passing through atmosphere (expected to be thinner at each higher elevation) the  wave will be refracted towards the Earth as demonstrated in Figure 3.4. 
 13.1 wliicll depicts a radar illuminating the surface at a grazing  angle 4. It is assumed that ttie width of the area A, is determined by the azimuth beamwidth  0,. but that the dimension in the range ditiiension is detern~iricd by the radar pulse width r  rather than the elevation beamwidth. 
 BEAM INTERFERENCE CANCEL 
  1  =  1   COSP ;1   )TANP  =   COSP ;1   )  = 4ABLE  SHOWS THESE PARAMETERS FOR AN EIGHT 
 A plane orthogonal to the vertical axis will gener - ate a circular feature whose radius increases with depth. A typical example is given  in Figure 21.28, which shows the C-scans from an anti-tank mine buried at different  depths with the center of the mine shown as an overlay. These images represent an  unfocussed representation of the target as a result of the 3D spatial convolution of the  antenna pattern with the target. 
 PRESSION IS CONSEQUENTLY REDUCED&)'52%  0ROCESSING OF 0RIMITIVE 4ARGET DETECTIONS AND 2ADAR 4ARGET 2EPORTS IN -4$ ))                 
 J. Roy. Meteor. 
 Summary of errors. The contributions of the various factors affecting the tracking error  are summarized in Fig. 5.14. 
 Hirst, H., and K. E. McKee: Wind Forces on Parabolic Antennas, Microwaoe J., vol. 
 TIONALLY EFFICIENT 7E BEGIN WITH THE STRUCTURE IN &IGURE  A  WHICH SHOWS THE FILTERING  IN DETAIL USING  S  TO INDICATE EACH CLOCK 
 1–127. 20. Schmidhuber, J. 
 Although a computer can be programmed to recognize and reject false tracks, too many false  tracks can overload the computer and result in poor information. It is for this same reason of  avoiding computer overload that the radar used with &pT should be designed to exclude  unwanted signals, as from clutter and interference. A good ADT system therefore reqirires a  radar with a good-MTI and a good CEAE-(constant false alarm rate) receiver. 
 The last part ofthe duplexer section isanr-fswitch used intesting 1Microwave Duplaxrs, Vol.14.. 432 R-FCOMPONENTS [SEC. 1112 thereceiver sensitivity y. 
 AMBIGUOUS TARGET RETURN  WITHIN THE )00 4HE THIRD ROW OF PLOTS SHOWS THE OUTPUT IN TERMS OF RELATIVE POWER .O 2' /VERLAP TT   TG   TS  TB     )00   TG 4RANSMIT 0ULSE    -& /UTPUT h6OLTAGEv   -& /UTPUT h0OWERv  4IME .ORMALIZED BY 2ANGE 
 A prime motivation for the Canadian Radarsat SAR was monitor - ing of sea ice, which the system has been doing successfully since 1995.156,157 The  Russian X-band real-aperture radars in the Okean series have been used for similar  purposes.158–160 Snow cover on ice can mask ice scatter itself as with snow on land. Since the arctic  is relatively dry, most areas have little snow, but snow does make distinguishing ice  types difficult at times. This is particularly true in the Antarctic, where snow is more  prevalent on the sea ice.161 FIGURE   16. 
 MTIANDPULSEDOPPLER RADAR135 wherek=constant. Theangular frequency spectrum ofthistimewaveform isfoundbytaking itsFourier transform, whichis 00(2776t2 )SoU)=ktooexp- .t5exp(-j2nJt) dt In2J2t5]=klexp-2.776 (4.31) wherek1=constant. Sincethisisagaussian function, theexponent isoftheformJ2/2aJ where aJ=standard deviation. 
 33. Nathanson, F. E.: "Radar Design Principles," McGraw-Hill Book Co., New York, 1969. 
 Furthermore, the radar echo will depend on the moisture content of  the surf ace scatterers. snow cover. and the stage or growth of any vegetation. 
 N’one ofthese items can take preeminence over the others since adesign aerodynamically orstructurally poor can prevent theradar setfrom being useful, just aswould aradome that had faulty transmission characteristics. The radome design must, therefore, beacompromise ofthese three major factors ifaccuracy and effectiveness oftheairborne unit aretobesecured. 9.22. 
  AND SEA 
 This portion of the leakage pulse is  termed the flat. Damage to the receiver front-end may result when either the energy contained  within the spike or the power in the fiat portion of the pulse is too large. "Typical .. 
 Image fusion results of Range–Doppler algorithm. Compared with the traditional method, the method proposed in this paper does not require additional image registration, which simpliﬁes the process of image fusion. It also avoids the effects of mismatch between images. 
 Griffiths and C. Tseng, “Adaptive array radar project review,” Hughes  Aircraft IR&D, performed at USC, July 18, 1990. 30. 
 (b) 45° aspect angle, (c) Broadside. face. The clutter cell area is given for beam- and range-limited cases in Sec. 
 It shouldbe obvious that in measuring the time of travel of a radar pulse or signal fromone ship to a target ship, the measurement must be an extremely short timeinterval. For this reason, the MICROSECOND ( µsec) is used as a measure of time for radar applications. The microsecond is one-millionth part of 1 second,i.e., there are 1,000,000 microseconds in 1 second of time. 
 These targets can be resolved at a resolution probability of 0.9 at separations TARGET SEPARATION IN RANGE CELL DIMENSIONS AR FIG. 8.22 Resolution capability of a log detector which uses the half of the reference cells with the lower mean. (Copyright 1978, IEEE; from Ref. 
 DAY CYCLES IN SUP 
 83 to 2.87 clutter visibility factor (V oc), 2.23 definitions, 2.19 to 2.23 dynamic range, 2.78 to 2.80 environmental considerations, 2.94 to 2.100 feedforward canceler, 2.39 filter design, 2.25 to 2.46 filter design for weather radar, 2.46 to 2.51 filter mismatch loss, 2.22 to 2.23 hardware considerations, 2.92 to 2.94 improvement factor, 2.19 to 2.20, 2.23 to 2.25, 6.17 to 6.18 interclutter visibility (ICV), 2.22 limitation due to scanning, 2.23, 2.38 limiting in receiver, 2.59 to 2.65 one-delay canceler, 2.35 optimum clutter filter design, 2.25 to 2.33 performance degradation due to limiting, 2.59 to 2.65 pulse compression considerations, 2.75 to 2.78 purpose of, 2.2 radial velocity ambiguity resolution, 2.89 to 2.91 range ambiguity resolution, 2.89 to 2.91 rules for, 2.92 to 2.94 in  SAR, 17. 23 and STC, 2.96 to 2.98 sensitivity velocity control (SVC), 2. 87 to 2.91, 2.99 to 2.100 signal-to-clutter ratio improvement (I SCR), 2.21 to 2.22 stability requirements, 2.65 to 2.78 staggered PRF design, 2.39 to 2.46 subclutter visibility (SCV), 2.6, 2.22 superclutter visibility, 2. 
 For receiving, the output from each radiating element may be het - erodyned (mixed) to an intermediate frequency (IF). All the various methods of scan - ning are then possible, including the beam-switching system described below, and  can be carried out at IF, where amplification is readily available and lumped constant  circuits may be used. Digital Beamforming.30–32 For receiving, the output from each radiating element  may be amplified and digitized. 
 Its chief application  has been for tracking-radar antennas.  An asymmetrical beam shape can be obtained by using only a part of the paraboloid. This  type of antenna, an example of which is shown in Fig. 
 OF 
 When looking into an approximately  20 knot wind, values of svv° were found to be constant within a few decibels for operat - ing frequencies where the ocean wave spectrum was approximately fully developed;  these observations provided a confirmation of Barrick’s first-order theory.80 By using  the antenna gain conventions stated earlier and assuming a semi-isotropic sea directional  spectrum, the value of svv° was calculated as –29 dB; the measured values were grouped  between −7 and +3 dB of this value over a 5 to 20 MHz frequency span. This experiment  provided the first direct measurements of the sea surface scattering coefficient. Of course, when the Bragg resonant waves are not fully developed, the scattering  coefficient will be proportionately less, as shown in Figure 20.13, compiled from data  sets recorded looking upwind or downwind with the Jindalee radar.76 Occasions when  the wind speed was insufficient to arouse the Bragg resonant waves to saturation levels  yielded scattering coefficient values up to 20 dB below the peak values. 
 OFFSET FREQUENCY  USING AN OPEN 
  )NT 3YMP   * 3 !JIOKA  h&REQUENCY 
 V . Trunk7) TABLE 7.1  CFAR Loss for Pfa = 10−6 and PD = 0.9*   Number of Pulses  IntegratedLoss for Various Numbers of Reference Cells (in dB) 1 2 3 5 10 ∞ 1 . 15.3 7.7 3.5 0 3 . 
 R. Dickey, Jr., “Theoretical performance of airborne moving target indicators,” IRE Trans .,   vol. PGAE-8, pp. 
 GEAR LOCKER OF EVERY SAILING SHIP WOULD CONTAIN A BOTTLE OF OIL TO QUIET THE SEA IN A STORM !LTHOUGH THE EFFECTIVENESS OF THIS PROCEDURE HAS ALWAYS BEEN SOMEWHAT CONTROVERSIAL  THERE IS NO QUESTION THAT OIL CAN PRODUCE A  SLICK OF SMOOTH WATER AT RELATIVELY LOW WIND  SPEEDS )N FACT  BIOLOGICAL OILS  PRODUCED BY BACTERIA  ALGAE  AND PLANKTON  CAN BE FOUND EVERYWHERE ON THE WORLDS OCEANS AND FORM NATURAL SLICKS IN THOSE REGIONS THAT COMBINE THE GREATEST OIL CONCENTRATION WITH THE LOWEST WIND SPEEDS  EG  CLOSE TO CONTINENTAL SHORELINES  -AN 
 When the radar wavelength is large compared with the circumference of a scattering  particle of diameter I) (Rayleigii scattering region), the radar cross section is  where I K I* = (c - I)/(( + 2), and c = dielectric constant of the scattering particles. The value  of I K l2 for water varies with temperature and wavelength. At 10°C and 10 cm wavelength, it is  RADAR CLUTTER 499 Radarequation formeteorological echoes.6971Thesimpleradarequation is p,G2J..2(ip - -.._------ r-(4n)JR4(13.14) Thesymbols weredefinedinSec.1.2.Inextending theradarequation tometeorological targets. 
 SCOPE PRESENTATIONS      AND  THE PROBABILITY DISTRIBUTIONS ASSUME A DIFFERENT FORM  &IGURE  A AND B SHOW  THE PRESENCE OF SEA SPIKES IN  
 Figure \6.2\a15 shows the phase and amplitude distribution required to form a uniform virtual distribution displaced behind the physical aperture. It can be shown that if the phase of the illumination function is reversed <(>' = — <|>, the desired virtual distribution function is displaced ahead of the aperture as shown in Fig. 16.21&. 
 " AND 3)2 
 This linear func - tion is known as a standard  gradient and is characterized by a decrease of 39 N-units  per kilometer, or an increase of 118 M-units per kilometer. A standard gradient will  cause traveling EM waves to bend downward from a straight line. Gradients that cause  effects similar to a standard gradient but vary between 0 and −79 N-units per kilometer  or between 79 and 157 M-units per kilometer are known as normal  gradients. 
 , 
 Digital signal processors are sampled signal systems.  Sampling  is the process by which a continuous (analog) signal is measured at regular  intervals of time (the sampling interval ), producing a sequence of discrete numbers  (samples) that represents the values of the signal at the sampling instants. The sam- pling frequency  is the inverse of the sampling interval and is typically designated fs. 
 The post-detection integration loss described by Fig. 2.8 assumes a perfect integraior.  Many practical integrators, however, have a "loss of memory" with time. 
 1200-1201. July, 1959.  64. 
 MEDIUM 02&  WHICH IS CHARACTERIZED  BY THE WAVEFORMS DOPPLER COVERAGE BEING UNAMBIGUOUS IN DOPPLER MAGNITUDE  BUT  NOT DOPPLER SENSE  FOR THE MAXIMUM TARGET DOPPLER OF INTEREST 4HE RESULTING SINGLE BLIND SPEED DUE TO MAIN 
 The introduction of digitally switched phase  stlifters employing either ferrites or diodes in the early 1960s made a significant improvenient  ir~ [lie ~,r;icticality of l>li;tscd arrays t1i:it could be clcctroriically stccrcd in two orthogon;tl  iirigular coordi~lates.  8.2 BASIC CONCEP'TS  ,411 array atlterlna corisists of a nuniber of i~idividual radiating elen~ents suitably spac~d witti  rcqpcct lo one i~nollier. .l~mplitudeFF~nd phase of tksignaIs.applied to each of the  eleriie~~ts are co~ltrolled to obtai~i the desired radiation pattern from the conibined action of all  the eleriients. 
 , .. 'I,., } ...... ,... 
      &)'52%  4YPICAL DIGITAL RECEIVER FRONT END   
 1This is,perhaps, nomore surprising than the fact that anordinary piece ofpaper displays, at nearly grazing incidence, specular reflection oflight, and itcan bemade plausible bysome argument such asthis: InFig. 2.13, two parallel rays, ABand DE,strike a“rough” surface, the roughness consisting ofa single bump ofheight h. The reader will find with little trouble that the netpath difference between thetwo rays ~F—ABisjust 2hsinO.If IThereflection coefficient would have tobesubstantially lessthan 1tochange the result significantly, sofarastheradar problem isconcerned.. 
 pp.883884. May.1968. 64.Hollis.J.S..andM.W.Long:ALuneburg LensScanningSystcm, IRETraIlS.,vol.AP-5,pp.2125. 
 This results in the received signal being FIGURE  2.9 Suppression of multiple clutter sources by using a doppler filter bank ch02.indd   9 12/20/07   1:42:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 Lab. Rept. 8698, June 30, 1983. 
 LAPSE  DETECTION PICTURE SHOWN IN &IGURE A   CONSISTING OF TARGET DETECTIONS  FALSE ALARMS  AND CLUTTER  INTO A TRACK PICTURE SHOWN IN &IGURE  B   CONSISTING OF TRACKS ON REAL TARGETS  OCCASIONAL  FALSE TRACKS  AND OCCASIONAL DEVIATIONS OF TRACK POSITION FROM TRUE TARGET POSITIONS &IGURES A AND  B ALSO ILLUSTRATE SOME OF THE CHALLENGES OF AUTOMATIC TRACK 
 Ashadow gridtopulse-modulate theheamcan alsobeincluded. Afterdelivering theird-cenergytotheRFfield,theelectrons areremoved by thecollector electrode. TheRFsignaltobeamplified entersviatheinputcouplerandpropa­ gatesalongtheslow-wave structure. 
 TerraSAR-X.  TerraSAR-X is the first civilian dedicated space-based SAR at  X band. Its 4.8 m by 0.8 m antenna is a two-dimensional active array of 384 T/R  modules. 
 Radio Science, vol. 12, pp. 355 364, May-June. 
 DURES LINEAR DETECTOR WITH 4!  }}MS  LINEAR DETECTOR WITH 4" }M  AND LOG DETECTOR  WITH4#  }M  WHERE THE CONSTANTS  !  "  AND # ARE USED TO OBTAIN THE SAME  0FA FOR  ALL DETECTORS 4HE ESTIMATES }MAND}SOF L AND R WERE OBTAINED FROM EITHER   ALL THE  REFERENCE CELLS OR   THE LEADING OR LAGGING HALF OF THE REFERENCE CELLS  CHOOSING THE  &)'52%  -ODIFIED GENERALIZED SIGN TEST PROCESSOR AFTER ' 6 4RUNK ET AL  . Ç°Óä  2!$!2 (!.$"//+  HALF WITH THE LOWER MEAN VALUE 4HE FIRST SIMULATION INVOLVED TWO TARGETS SEPARATED BY        OR  RANGE CELLS AND A THIRD TARGET  RANGE CELLS FROM THE FIRST TARGET 7HEN THE TWO CLOSELY SPACED TARGETS WERE WELL SEPARATED  EITHER   OR  RANGE CELLS  APART  THE PROBABILITY OF DETECTING BOTH TARGETS  0 $  WAS    FOR THE LINEAR DETECTOR  WITH4!  }}MS    0$    FOR THE LINEAR DETECTOR WITH 4" }M AND 0$     FOR THE LOG DETECTOR ! SECOND SIMULATION  INVOLVING ONLY TWO TARGETS  INVESTIGATED THE EFFECT OF TARGET SUPPRESSION ON LOG VIDEO  AND THE RESULTS ARE  SUMMARIZED IN 4ABLE   4HE MAXIMUM VALUE OF  0 $ IS OBTAINED WHEN BOTH TARGETS HAVE AN  3. OF  D" )F ONE  OF THE TARGETS HAS A LARGER  3. THAN THE OTHER TARGET  SUPPRESSION OCCURSEITHER TARGET   SUPPRESSES TARGET  OR VICE VERSA !LSO  ONE NOTES AN IMPROVED PERFORMANCE FOR A SMALL 3.  TO  D"  WHEN CALCULATING THE THRESHOLD USING ONLY THE HALF OF THE REFERENCE  CELLS WITH THE LOWER MEAN VALUE 4HE RESOLUTION CAPABILITY OF THE LOG DETECTOR THAT USES ONLY THE HALF OF THE REFERENCE CELLS WITH THE LOWER MEAN IS SHOWN IN &IGURE  4HE PROBABILITY OF RESOLVING TWO  EQUAL 
 The probability-density function for  the envelope of II independent noise samples is the product of the probability-density function  for each sample. or  " Pn(11, t'i) = rJ Pn(v;) ( 10.33)  i= I  The prohahility-dcnsity function for ith noise pulse Pn(v1) is given by Eq. (2.21), rewritten  ( v~) Pn(v;) = V; exp -i (2.21)  where I'; is the ratio of the envelope amplitude R to therms noise voltage t/1//2. 
 On setting the cursor to bisect the pip, the cursor should be viewedfrom a position directly in front of it. Electronic bearing cursors used withsome stabilized displays provide more accurate bearing measurements thanmechanical bearing cursors because measurements made with the electroniccursor are not affected by parallax or centering errors. Heading Flash Alignment For accurate bearing measurements, the alignment of the heading ﬂash with the PPI display must be such that radar bearings are in close agreementwith relatively accurate visual bearings observed from near the radarantenna. 
 This limitation is a function of the antenna pointing angle, the MTI filter response, and the sidelobe pattern. If the sidelobes are relatively well distributed in azimuth, a measure of performance can be obtained by averaging the power returned by the sidelobes. The limiting improvement factor due to sidelobes is *P G4Ce) do /si limit = —^ (16.11) JV(GWB where the lower integral is taken outside the main-beam region. 
 By measuring  the direction in which the antenna is pointing when the echo is  received, both the azimuth and elevation angles from the radar  to the object or target can be determined. The accuracy of  angu lar measurement is determined by the directivity, which is  a function of the size of the antenna.  . 
 SCANNING OVER THE VOLUME COV 
 Many radars are designed to operate at microwave frequencies, where narrow beamwidths can be achieved with antennas of moderate physical size. The above functional description of radar antennas implies that a single an- tenna is used for both transmitting and receiving. Although this holds true for most radar systems, there are exceptions: some monostatic radars use separate antennas for the two functions; and, of course, bistatic radars must, by definition, have separate transmit and receive antennas. 
 Near surface  targets of interest will often have radial velocities of a few miles per hour for long  periods of time, which forces the detection of ground moving targets well into main- beam clutter. Phase monopulse, DPCA, or STAP processing allows the first order  cancellation of clutter for many slow-moving targets. Unfortunately, clutter does not  always have well-behaved statistical tails, and to maintain a constant false alarm rate,  the threshold must be raised for endoclutter targets. 
 The unwanted image is then rejected using the FIR filter with impulse response h(n)  producing output ˆ( )x n with spectrum ˆ( )Xw. Finally, the sample rate is reduced by  ch06.indd   41 12/17/07   2:04:09 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The data clearly show that measurement of radar backscatter at only one aspect  angle is not sufficient to determine wind speed and direction. The Seasat scatterometer  used two look angles (separated by 90 °), but the resulting retrievals had as many as  FIGURE 18.18  Typical backscatter strength (vertical axis) from a  wind-driven sea surface, as a function of wind speed (modeled data) and  the wind direction relative to the radar’s look direction (horizontal axis).  Similar families of curves correspond to the radar’s polarization (usually  HH or VV) and angle of incidence. 
 The occurrence of this type of clutter is greater at night and is much more prevalent in the auroral zones and around the magnetic equator. As stated earlier, Elkins32 has developed a model for HF auroral clutter that can be used to predict target obscuration when the transmis- sion path is through the auroral region. Lucas has provided spread-F maps for inclusion in ionospheric models so that spread doppler clutter can be predicted.40 Ionospheric irregularities that scatter back to the radar receiver occur much more often at night than by day at any latitude. 
 There is no need to include closed loop adjustments to  the TACCAR modulation frequency. The optimization of the AMTI clutter cancella - tion filter is achieved in the STAP processing as opposed to adjusting the location of  main-beam clutter to fit a fixed AMTI filter. In order to implement STAP and electronic scanning in this radar, all 18 elements  of the phased array antenna are processed on transmit and receive. 
 Comparative Analysis with other Non-Linear Time-Series Models We also conducted an experiment based on a polynomial model to generate the time-series deformation over this route, according to [ 25]. The temporal displacement over the two feature points are shown in Figure 11(we only showed the LP-deformation component). As Figure 11shows, we can see that in the early stage (the period from June 2014 to February 2015) the temporal variation characteristic was a stable deformation velocity, whereas an obvious signiﬁcant increase in deformation velocity was present in the later stage (the period from March 2015 to November 2015). 
 RADAR DIGITAL SIGNAL PROCESSING  25.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 required to realign the data in the two paths, and this causes the I and Q output values  to be effectively sampled at the same instants. Signal-Sampling Considerations.  Actual devices and signals introduce errors. 
 Photo-Optical /11s1rumen1atio11 Engineers, vol. 128, "Effective Utilization of Optics in Radar  Systems," pp. 155-164, 1977. 
 Forradar receivers thenoisefigureisthemorewidelyusedterm,andiswhatisusedinthistext. Measurement ofnoisefigure.Thenoisefigureofaradarreceivercandegrade inoperation and causereduced capability. Therefore somemeansformonitoring thenoisefigureshouldbe provided inoperating radarssothataworsening ofreceiversensitivity canbedetected and corrected. 
 2: random change in acceleration at  each measurement interval; model no. 3: random change in velocity at each measurement interval; and  model no. 5: constant deterministic acceleration. 
 The wavelength region between 8cmand 25cmappears tobebest on thebasis ofallthese considerations. Though anoptimum wavelength cannot safely bespecified, wecan make three general remarks con- cerning thebest wavelength foralong-range ground-based system forair surveillance and control: 1.The choice ofthe 10-cm region for the setdescribed here was excellent, although awavelength asshort as8cmmight have been more desirable. 2.IfMTI istoplay animportant role infuture system performance, and ifimprovement inMTI performance with increasing beam- width issufficiently great, longer wavelengths may bedesirable. 
 Al'pert. Ya. L.: " Radio Wave Propagation and the lonosphcrc." Consultants Ht~reair. 
 P.: Low-Cost Processing and Display System for Radar Tracking and Intercept, IEEE  EASCON '75 Com1entio11 Record, pp. 108-A to 108G, 1975.  37. 
 So just about ten years ago radio experimenters were  attracted to the possibility of using metal tubes filled  with some insulating dielectric as ‘guides’ for electro-  magnetic waves. Almost at once it was realized that a  ‘hollow’ tube—<.g., filled with air only—was satisfactory  for the purpose, and that waves could in reality be  . Outer inner conductor conductor  &  luli ill  TRANSMISSION LINES  For wavelengths above about 50 metres the length and nature of the line connecting the transmitter or receiver to the aerial is of little relative importance. 
  
 ATING AT THE APPROPRIATE HIGH FREQUENCY WITH GOOD EFFICIENCY  WHILE DEMONSTRATING USEFUL POWER GAIN WITH ADEQUATE THERMAL MANAGEMENT PROPERTIES TO ENSURE HIGH RELI 
 The sliding spotlight mode, while increasing the azimuth resolution, is particularly aﬀected by scintillation artefacts due to the long integration time. The theoretical analysis of scintillation e ﬀects on the P-band spotlight SAR images was performed by introducing a novel scintillation simulator based on the reverse back-projection algorithm. SAR raw data for the sliding spotlight mode were simulated for both pointy and extended targets, under di ﬀerent 3. 
 (a) (b) (c)  Figure 9. The geometrical features of refocusing ship01 and ship02. ( a) Lengths of ships; ( b) Widths of ships. 
 The operating wavelength is 23.5 cm. This antenna is very similar to the SIR-A. Both are significant developments in large deployable antennas.6'37 The SIR-B antenna is similar except that it was mechan- REFLECTORWElGHT (Ib) KILOGRAMS DENSITY VARIES LINEARLY BETWEEN 24-FT-DIAMETER AND100-FT-DIAMETER REFLECTORS 24-FT-DIAMETER, 3-PLY GRAPHITE FACE SHEETS, 0.5-IN CORE 100-FT-DIAMETER, 6-PLY GRAPHITE FACESHEETS, 2-IN CORE . 
 A. Mondelli, and R. K. 
 Solid-state limiters. Solid-state PNandPINdiodescanbemadetoactasRFlimitersandare thusofinterestasreceiver protectors.42-44Ideally,alimiterpasseslowpowerwithoutattenua­ tion,butabovesomethreshold itprovides attenuation ofthesignalsoastomaintain the outputpowerconstant. Thisproperty canbeusedfortheprotection ofradarreceivers intwo differentf'implementations depending onwhether thediodesareoperated unbiased (self­ actuated) orwithad-cforward-bias current.Unbiased operation isalsoknownaspassive.Itis usedforlow-power applications. 
 Early warning monitoring of natural and engineered slopes with ground-based synthetic-aperture radar. Rock Mech. Rock Eng. 
 The phase noise of oscillators and other components is typically specified as the  multiplicative noise that rides on a continuous waveform, or CW phase noise. In pulse  doppler radar, transmit gating interrupts the continuous waveform to produce a pulsed  waveform. Gated  phase noise is the result of gating CW phase noise. 
 LIKE OUT TO THE  &)'52%  #ELL 
 Another difficulty is that the phase as well as the magnitude of the element pattern varies with  position. As a result of the cylindrical geometry, the radiation pattern is only partially separ­ able in spatial coo1di11111cs. (11 can he considered as the product of a ring.array patlcrn and a  linear-array pattern.) Tl1c azimuth pattern of a vertical cylindrical array changes with both  azimuth and elevation as the beam is scanned in elevation. 
 NORMALIZED SINE-SPACE ANGLE (RELATIVE TO CROSSOVER) (a) FIG. 20.4 Fundamental accuracy, (a) Two-beam sequential lobing: uniform (sin irw/irw) sum beams transmit and receive; separation = Aw; nonfluctuating target; N = one pulse per beam. sion of the sensitivity factor k = K\/L versus a similarly normalized sine-space elevation angle of arrival, u = ZA sin (6). 
 MITTER APPLICATION #OMPROMISES NEED TO BE MADE DEPENDING ON THE APPLICATION 4HE RADAR EQUATION FOR A SURVEILLANCE RADAR ONE THAT HAS TO COVER A FIXED VOLUME  OF SPACE ON A REGULAR BASIS  INDICATES THAT THE MAXIMUM RANGE OF SUCH A RADAR IS PRO 
 6.13] HOMING 201 application, since thetarget speed ismuch higher (and much more nearly that oftheintercepting aircraft), and since homing must becarried outin two dimensions instead ofone. An early AIequipment was designed bytheBritish asanextension toAIofthe design principles ofASV Mark II. Itwas designated AI lMark IVbythe British; asimilar system made forthe U.S. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 operating procedure for planetary or lunar radars, for which high image resolution is  not required and the spacecraft-to-Earth data link is severely limited. 
 POLARIZATION  DOPPLER RESEARCH RADAR OPERATED BY THE .ATIONAL #ENTER FOR !TMOSPHERIC 2ESEARCH  .#!2  4HE SYSTEM PERMITS SIMULTANEOUS MEASUREMENTS OF THE REFLECTIVITY FACTOR ON TWO WAVELENGTHS  DOPPLER PARAMETERS ON THE 3 
 G •..  '-fJs{fp .· Os fp  11a = 7!;i = ~-~ ~~;;, (2.30)  where On = antenna beamwidth, deg  J~ pulse repetition frequency, Hz  (}5 antenna scanning rate, deg/s  w.,, antenna scan rate, rpm  Typical parameters for a ground-based search radar might be pulse repetition frequency  300 Hz, 1.5° beamwidth, and antenna scan rate 5 rpm (30°/s). These parameters result in  15 hits from a point target on eac:h scan. 
 12. i!ollis, R.: False Alarm Time in Pulse Radar, Proc. IRE, vol. 
 The development of the solid quartz delay iine for MTI  application in the 1950s offered greater convenience than the liquid lines.j3 The solid line is  constructed of many facets so that a relatively long delay time can be obtained with a small  volume by means of multiple internal reflections. In one popular design the quartz was cut as  a 15-sided polygon in which the acoustic signal made 31 internal passes to achieve a total  delay time of 1 ms.  Electrostatic storage tubes have also been used for MTI delay  line^.^^-^'' The signals are  stored in the form of electrostatic charges on a mosaic or mesh similar to that of a TV camera  tube. 
 Ewing and L. W. Dicken, “Some Applications of Bistatic and Multi-Bistatic Radars,” in Int. 
 Asinallcases oftransmission ofanonsymmetncal signal through an a-ccoupling, the d-ccomponent ofthesignal islost. This presents one ,i–”--~ APrimary signal (unbalanced) M------------ B%con&ry s,gnal _ (no clamping) B,Secondary wgnal (when clamped) 4Salanced waveform— (EXP:cdee time Automat,c trdgger { ‘-~-Sweep waveform — generation Modulator Ltr,aer 1 I I I FIG.1345.-Resolved-sweep PPI methods. ofthemost serious difficulties involved inthis technique. 
 SURE EXPERIMENTS.   42!#+).' 2!$!2   °Óx ! SIMILAR 8 
 It was also found that a0 was proportional to the elevation  angle over grazing angles from 2° to 10°, but was inversely proportional to grazing angle over  the region from 1 ° to 2°. (The increase of a0 with decreasing grazing angle is similar to the  behavior of land clutter but not sea clutter.) The scatterometer, a radar which measures cr0 as  a function of incidence angle in the region near vertical incidence, has been used as an ice sensor  and to differentiate between first-year and multi-year ice.65  Radar can also detect large icebergs, especially if they have faces that are nearly per­ pendicular to the radar direction of propagation.33 Icebergs with sloping faces can have a  small echo even though they may be large in size. Growlers, which are small icebergs large  enough to be of danger to ships, are poor radar targets because of their small size and shape. 
 These systems were very difficult to develop and mod - ify, but in order to achieve the required system performance, it was the only option  available. Many systems were built using Application-Specific Integrated Circuits  (ASICs), which are custom devices designed to perform a particular function. The  use of ASICs allowed DSP systems to become very small with high performance. 
 Other types of lenses based or? the principle of nonuniform index of refraction have been  d~scribed.~~.~".~~ Hornogerieoi~s sptierical lenses with uniform dielectric constant are also of  interest69 " if tlie index of refractiori is not too high and if the diameter is not greater than  about 30i. They can be competitive to the Lunebuig lens, especially for high-power  applications.'  Lens  tolerance^.'.^ In general, tlie mechanical tolerances for a lens antenna are less severe than  for a reflector. A given error in the contour of a mechanical reflector contributes twice to the  error in ttie wavefront because of the two-way path on refection. 
 In Sec. 10.2 it was  shown that the frequency-response function of the matched filter was given, except for a  constant and a time delay, by  where in the notation of Sec. 10.2, S*(f) is the complex conjugate of the Fourier transform of  the input signal in the absence of noise and N,(,f) is the spectrum of the input noihe (the  Fourier transform of the input noise voltage). 
 ' \  \.,  \ oo  I  :J \  ~ ----\---~\~  ,.,.-,- \  \ \ CTr/CTo __ 900 2 3 4  I ~-1---7;_- / ' /\ -- \  00  I  • • k 4A-..1  (c) 00  I  • •  ~ 2A k  (b) THE RADAR EQUATION 39  Figure 2.15 Polar plots of a,/a0 for the two-scatterer complex target (Eq. (2.37)]. (a) I= ,l.; (b) l = 2-l.;  (c) l = 4).. 
 7HILE 
 AMPLIFIER HAS USUALLY BEEN PREFERRED FOR RADAR APPLICATIONS FOR THE SAME REA 
 The filter sidelobes between 0.8 and 1.0 doppler provide the specified chaff rejection of 48 dB. A mirror image of this filter is used for the third moving doppler filter. (The mirror-image filter has coefficients that are complex conjugates of the original fil- ter coefficients.) Figure 15.26c shows the first filter designed for response at zero doppler. 
 36. Russia’s Arms Catalog, vol. 5, Air Defense, Moscow: Military Parade Ltd., 1997. 
 The correspond- ing autocorrelation function is RcM = PC exp (-4-ITOy2T2) exp (-jlitfrf (15.17) For two pulses separated in time by the interpulse period T the complex corre- lation coefficient between two clutter returns is pr = exp (-4ira/r2) exp ( - j2itfdT) (15.18) The second factor in this expression represents the phase shift caused by the doppler shift of the clutter returns. For a known target doppler shift the received target return can be represented by an Af-dimensional vector: s = Psf (15.19) where the elements of the vector f are/ = exp [/2ir/X]. On the basis of this de- 1 STAGGER (SCAN) <<*B) . 
 44.White,J.F.:"Semiconductor Control," ArtechHouse,Dedham, Mass.,1977. 45.Brown.N.J.:Control andProtection Devices, IEEENEREM 74Record, pt4:RadarSystems and Components, Oct.28-31,1974,IEEECatalog No.74CHO9340NEREM, Library ofCongress Catalog no.61-3748. 46.Kupke.W.F.,T.S.Hartwick, andM.T.Weiss:Solid-State X-Band PowerLimiter, IRETrans.,vol. 
 For an TV-transducer cascade, the system input noise temperature (with the antenna terminals considered to be the system input terminals) is then given by T.-T. + Z -£ .2.33, Here T0 is the antenna noise temperature, representing the available noise power at the antenna terminals, and G, is the available gain of the system between its input terminals and the input terminals of the /th cascaded component. (By this definition G1 = 1 always.) To illustrate these principles concretely, this formula will here be applied to a two-transducer cascade representing a typical receiving system (Fig. 
  cov 0 2re ery mintc R    The receiver does not listen during the transmitting pulse, because it needs to be disconnected from  the transmitter during transmission to avoid damage. In that case, the ech o pulse comes from a  very close target. Targets at a range equivalent to the pulse width from the radar are not detected. 
 (ILL    PP n. Î°£ÀLÀiÊ / >iÃÊ °Ê >Þ ,OCKHEED -ARTIN #ORPORATION Ài`Ê °Ê-Ì>Õ`> iÀI .AVAL 2ESEARCH ,ABORATORY RETIRED  Î°£Ê -9-/ 
 Although random errorsmayberelatively small,theireffectonthesidelobe radiation canbelarge.Systematic errorsareusuallythesame fromantenna toantenna inanyparticular designconstructed bysimilartechniques. Onthe otherhand,randomerrorsdifferfromoneantenna t<?thenexteventhoughtheybeofthesame designandconstructed similarly. Therefore theeffectofrandomerrorsontheantenna pattern canbediscussed onlyintermsoftheaverage performance ofmanysuchantennas orinterms ofstatistics. 
 Apart from the need to adapt to the changing ionosphere and noise environment,  HF radars are frequently tasked with a variety of missions to be conducted more or  less concurrently, with time-varying priorities. These will generally involve different  waveforms, task-specific constraints on frequency (in addition to propagation con - siderations), differing requirements in terms of acceptable propagation quality, and  so on. A common example is the desire to search for ships and aircraft concurrently. 
 Detailed requirements on electromagnetic emis - sions and immunity to the electromagnetic environment are mandated. IEC 60945 also  specifies general requirements on ergonomics, software development, and safety. A  further set of IEC standards contained within the IEC 61162 series,13 define the mes - sages used for navigation and radiocommunications equipment to interchange digital  data. 
 THRESHOLD SYSTEM THAT DOES NOT UTILIZE EXCELLENT COHERENT PROCESSING 4HREE MAIN APPROACHESADAPTIVE THRESHOLDING  NONPARAMETRIC DETECTORS  AND CLUTTER MAPSHAVE BEEN USED TO SOLVE THE NONCOHERENT  FALSE 
 The transmitter sends out pulses and during the off - time, the receiver listens for the return echo. The pulse -off  time is the period the receiver can listen for the reflected echo.  The longer th e off-time, the further away the target can be  without the return delay putting the received pulse after the  next transmitted pulse. 
 Sensors 2019 ,19, 346. [ CrossRef ][PubMed ] 16. Kanberoglu, B.; Frakes, D. 
 In digital beamforming (DBF), the RF signals  are digitized at either each individual element or each subarray. Once the signals   have been digitized, various weighted combinations of the digitized signals can  be used to form multiple simultaneous receive beams. Figure 13.38 shows array   architectures for analog beamforming and DBF at the element and subarray level. 
 III, the local oscillator was housed in the indicator unit, which also had the controls for adjusting the crystal mixer current and mechanically tuning theklystron. Con ﬁdence in the stability of the klystron had improved and it was now housed remotely from the operator in the TR unit. The mechanical tuning of the klystron was undertaken remotely by a motor, commanded from control unit type444. 
 The width  of the range gates depends upon the range accuracy desired and the complexity which can be  I tolerated, but they are usually of the order of the pulse width. Range resolution is established by  gating. Once the radar return is quantized into range intervals, the output from each gate may  be applied to a narrowband filter since the pulse shape need no longer be preserved for range  resolution. 
 TO 
   PP n  -ARCH   4 4 $EBSKI AND 0 7 (ANNAN  h#OMPLEX MUTUAL COUPLING MEASURED IN A LARGE PHASED ARRAY  ANTENNA v -ICROWAVE *  PP n  *UNE   0 7 (ANNAN AND - ! "ALFOUR  h3IMULATION OF A PHASED 
 N. Held, W. E. 
 TECTURE BASED EITHER ON #OMMERCIAL OFF THE 3HELF #/43  TECHNOLOGY OR CUSTOM 6ERY ,ARGE 3CALE )NTEGRATION 6,3)  DEVICES )N THE LITERATURE n IT HAS BEEN SHOWN THAT  A WIDE SPECTRUM OF TECHNOLOGIES CAN BE USED LIKE &IELD 0ROGRAMMABLE 'ATE !RRAYS &0'!   #OORDINATE 2OTATION $IGITAL #OMPUTER #/2$)#  IMPLEMENTED WITH 6,3) AND OPTICAL COMPUTERS 0IONEERING WORK ON THE USE OF #/2$)# FOR ADAPTIVE NULL 
 6, pp. 200–228, 1976.  86. 
 With the increase of the synthetic angle, because of the reﬂector geometry, shadowing, and coherent scintillation, the problem of aspect dependent scattering [ 1,2] arises. Traditional imaging methods are based on the isotropic assumption. It means that the scattering is constant in the synthetic aperture angle, which is not valid in WASAR. 
 48-55. January, 1977.  27. 
 Pun nett, M. S.: Developments in Ground Mounted Air Supported Radomes, I £EE 1977 Mechanical  Engineering in Radar Sj•mposiw11, Nov. 8-10, 1977, Arlington, Va., pp. 
 NOISE RATIO REQUIRED TO OBTAIN THE SAME PROBABILITY OF DETECTION WITH ECLIPSING AND STRADDLE  AS IN THE CASE WHERE THE TRANSMIT PULSE IS RECEIVED BY A MATCHED GATE WITH NO STRADDLE 3INCE THE DETECTION CURVE CHANGES SHAPE  THE  LOSS DEPENDS ON THE  PROBABILITY OF DET ECTION SELECTED  WHICH  IS DEPICTED IN &IGURE  &OR ACCURATE RESULTS  ECLIPSING AND RANGE GATE STRADDLE LOSS MUST BE COMPUTED TOGETHER ! LESS ACCURATE APPROXIMATION COMPARES THE AVERAGE SIGNAL 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 19.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 polarimetric measurements allow one to estimate the parameters of the gamma func - tion form of the DSD,127 which may further improve rainfall estimation. 
 (Percentage bandwidth = 100 Afg0 .)  A frequency-scan radar requires a considerable portion of the available band of a radarJo \ -  be devoted to beam steering. Although this is a simple method of electronic steering, it does  not usually allow the frequency band to be used for other purposes, such as for high range-  resolution or for frequency agility. \ \  If too short a pulse (too wide a signal bandwidth) is used in the frequency-scan array, the  pattern will be distorted. 
 Rogers: Signal-to-noise Improvement through Integration in a Storage  Tuhe. Proc. IRE, vol. 
 To prevent spectrum aliasing, a large PRF is required. Reference [ 8] gives a design to reduce the PRF, and the PRF is the sum of the Doppler bandwidth of multi-beam signals, but the method limits beam pointing. In addition, when using the ultrahigh speed platform, the Doppler bandwidth of the multi-beam signal becomes large. 
 LAG ERROR 4HERE IS AN OPTIMUM BANDWIDTH THAT MAY BE CHOSEN TO MINIMIZE THE AMPLITUDE OF THE TOTAL ERRONEOUS OUTPUTS INCLUDING BOTH TRACKING LAG AND RANDOM NOISE  DEPENDING  UPON THE TARGET  ITS TRAJECTORY  AND OTHER RADAR PARAMETERS 4HE OPTIMUM BANDWIDTH FOR ANGLE  TRACKING IS RANGE 
 81. Cantrell, B. H., G. 
 129. Peeler, G. D. 
 Also, the antenna gain can be greater at the higher frequencies, a factor  often favoring the radar when confronted with jamming, as seen by Eqs. (14.213) and (14.30).  f~urtl~crrnore. 
 Onthe other hand, iftheresponse oftheamplifier isrelativelyFIG.2.4.—Variation of output signal power a andoutput noise power b with bandwidth atcon- stant pulse duration. very “fast, theo-utput will quickly reach alevel determined solely bythe input power and the gain, and independent ofCB. Thus ifweplot peak output signal power against 6$forconstant (during thepulse) input power acurve like aofFig. 
 The diﬀerence of adjacent elements in Rgeis ﬁxed. 4. We acquire the element in the sequence Rgthat is numerically closest to the element Rge(j), which we deﬁne as Rne. 
 Picard Medal for Radar Technologies and Applications..     iii RADAR HANDBOOK Merrill I. Skolnik Editor in Chief Third Edition New York Chicago San Francisco Lisbon London Madrid Mexico City Milan New Delhi San Juan Seoul Singapore Sydney Toronto. 
 vol. 62.  pp. 
 107. ( ienl, 11.: The Bootlace Aerial, RRL J. (Royal Radar Establishment, Malvern. 
 also called the feedback integrator, adds each new sweep to the sum of all  the previous sweeps. To prevent unwanted oscillations, or" ringing," due to positive feedback,  the sum must be attenuated by an amount k after each pass through the line. The factor k is the  gain of the loop formed by the delay line and the feedback path. 
 The sensors may contain dedicated motion sensing, but long-term navigation is pro - vided by the vehicle management global positioning system and inertial navigation sys - tem (GPS/INS). The on-radar motion sensing must sense position to a fraction of the  transmitted wavelength over the coherent processing interval. This is usually done with  inertial sensors such as accelerometers and gyros with very high sampling rates. 
 SPACE 0ROPAGATION -ODEL  4HE SIMPLEST PROPAGA 
 LAGE OF THE FABLED -ACH 
 END DESIGN FROM  
 Subject tothis upper limit, the choice off, isdetermined by considerations ofbandwidth, response time, and apparatus convenience. The smaller j,,the narrower the band and the slower the response. Also, the beat frequency, which varies with ~,,should bekept inarange suitable forthefrequency meter tobeused. 
 13. Page, R. M.: Munopt~lsc Radar, IRE Natl. 
 I By 1938 the Admiralty was showing signi ﬁcant interest in the potential for air to surface vessel (ASV) radar. A basic design had been established using horizontally polarised side-looking Yagi arrays [ 1]. However, with the increase in international tension between September 1938 and the outbreak of war on 1st September 1939, ASV development was given lower priority than ground-based air defence and air- interception (AI) radar. 
 [ CrossRef ] 24. Meyer, F.; Chotoo, K.; Chotoo, S.; Huxtable, B.; Carrano, C. The inﬂuence of equatorial scintillation on L-band SAR image quality and phase. 
 Mass ..  1977.  86. 
 (d .k ) 0.00349r1 6 0.00224r tlcnuat1011 at 0°C Bi m = il4 · + A ( 13.29)  where r = snowfall rate (mm/h of melted water content). and ) = wavelength, cm.  10  E <10'  CD 'O . 
 8. That is the result of  putting a square wave-form through a differentiating  circuit. Now a rather different effect is obtained if the  circuit is arranged as in Fig. 
  
 ITY  PRECISION  AGILITY  AND VERSATILITY OVER ANALOG TECHNIQUES 4HE MAIN LIMITATIONS ARE THE NOISE AND SPURIOUS SIGNALS AS DESCRIBED BELOW 4HE GENERAL $$3 ARCHITECTURE IS SHOWN IN &IGURE  4HE DOUBLE ACCUMULATOR ARCHITECTURE  COMPRISING THE FREQUENCY AND PHASE ACCUMULATORS  ENABLES THE GENERATION OF #7  LINEAR &- CHIRP   NONLINEAR PIECE 
 BASED TRAPPING LAYER  4HIS DUCT IS REFERRED TO AS A  SURFACE DUCT AND IS ILLUSTRATED IN &IGURE  4HE DOTTED  LINE IN THE FIGURE SHOWS THE VERTICAL DIMENSION OF THE DUCT FROM BOTTOM TO TOP 4HE SECOND TYPE OF SURFACE DUCT IS CREATED FROM AN ELEVATED TRAPPING LAYER 4HIS DUCT IS COMMONLY REFERRED TO AS A  SURFACE 
 Complex, decimated       baseband signal–75 MHz FIGURE 25.15  Time-domain implementation of a direct digital downconverterREAL PART OF   COMPLEX FILTER  IMPULSE RESPONSE75 MHz IF  SAMPLED  @ 100 MHzI Q50 MHz IMAGINARY PART OF  COMPLEX FILTER  IMPULSE REPONSE2 2100 MHz +1, –1, +1, –1,... ch25.indd   12 12/20/07   1:39:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 47. Bates, D. J., R. 
 Implementation.  Figure 6.12 shows the basic block diagram of a I/Q demodual - tor. The IF signal described by Eq. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°È  9 1UILFEN  " #HAPRON  & #OLLARD  AND $ 6ANDEMARK  h2ELATIONSHIP BETWEEN %23 SCATTEROM 
 49. lllahy. F. 
 (IRE), 1958, p. 405.  20. 
 Therefore the frequency-response function of the portion of the receiver included'between the  antenna terminals to the output of the IF amplifier is taken to be that of the IF amplifier alone.  Thus we need only obtain the frequency-response function that maximizes the signal-to-noise  ratio at the output of the IF. The IF amplifier may be considered as a filter with gain. 
 K.: "Gallium Arsenide Technology," Howard W. Sams & Co., Indianapolis, 1985, pp. 189-300. 
 13.6 Sea clutter from a tower platform with power-law wind-speed dependence defined by linear regression. (From Chaudhry and Moore,31 © 1984, IEEE.) Nevertheless, the imposition of a power-law relation provides a convenient way to visualize trends in the behavior of sea clutter with wind speed. The var- ious aircraft measurements referred to above27"29 as well as data from a tower in the North Sea30'31 were all treated in this way, yielding plots of a° as a function of wind speed and grazing angle of the form shown in Fig. 
 Wickenden, B. V. A., and W. 
 If the atmospheric index of  refraction were to increase, rather than decrease, with increasing height, the rays would curve  upward and the radar range would be reduced as compared to normal conditions. This is  called srthrefractiott. Its occurrence is rare. 
  
 Moreover, even on a very small part of this curve  we do not get so near to linearity as we do with the flat  part of the anode-voltage and anode-current characteristic  of a screened pentode.  For the discharge we may arrange that the condenser  value of voltage is suddenly reduced by automatic dis~.  charge through a gas-filled triode such as a thyratron,  and we can set the circuit values so that the condenser  will continuously be charged and discharged, producing  a succession of saw-tooth wave-forms. 
 PROCESSOR  AND THE SPECTRUM WIDTH OF THE RETURNS FROM CLUTTER 4HE CONCEPT OF A HIGH 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 The radiating elements are not isotropic but have a radiation pattern Ee(q ), known  as the element factor  or element pattern ; then the complete radiation pattern E(q ) is  the product of the array factor and the element pattern:  E E E EN s Ne a e ( ) ( ) ( ) ( )sin [ ( /)sin] sin[q qqq= = θπ λ π( ( /)sin] sλq (13.3) An approximation to the pattern of Eq. 13.2 is in the form  Ea a( )sin [( / ) sin] ( / ) sinqq q=π λ π λ (13.4) where the effective aperture is a = Ns, which extends by s/2 beyond the centers of  the end elements. 
 (15.15). As shown by Capon,13 the weights of the optimum MTI are found as the eigenvector corresponding to the smallest eigenvalue of the clutter covariance matrix and the MTI improvement factor is equal to the inverse of the smallest eigenvalue. In Fig. 
  
 Because of lack of knowledge of actual autocorrelations, most theory has been developed with artificial functions that are chosen more for their integrability than for their fit with nature; selection among them has been on the basis of which ones yield the best fit between the- oretical and experimental scatter curves. The correlation function first used42 was gaussian: p(6) = e-?lj} (12.5) where L is the correlation length. Not only is this a function that makes the in- tegral analytically tractable, but it also gives exactly the same results as geomet- ric optics.43 Since it fails, like geometric optics, to explain frequency variation, it cannot be a truly representative correlation function, although it gives a scatter- ing curve that fits several experimental curves near the vertical. 
 The refle c- tion cross- section σ is defined in the respective far field.  For a Radar with the aperture diam e- ter a=10 cm of the antenna, this is:   € RFF=2⋅a2 λ=5m (13.2)  For an object, e.g. a truck, with a width d the range becom es considerably larger:  . 
 P2 codes are similar, but the phase is symmetric with the following characteristic:  φ π πi j M M M i j M j,{( )[( ) / ] ( ) ( ) }[ ] = − − − + − 2 1 1 2  (8.20) The P3 and P4 codes are derived by essentially converting an LFM waveform to  baseband.35 These tend to be more doppler tolerant than the Frank, P1, or P2 codes,  and are also more tolerant of precompression bandwidth limitations that appear in  radar systems. The phase of the P3 code is given as  ϕπ nNn =2    n = 0,…, N – 1  The P4 code phase relationship is similar:  φππnn Nk = −2     0 ≤ n ≤ N  Table 8.5 summarizes the phase and autocorrelation characteristics of the Frank  code and the Lewis and Kretschmer P1 through P4 polyphase codes.FIGURE   8. 20 Ambiguity function of a Frank code of length 64 ( M = 8) 001 −1−11 f/Bt/tp ch08.indd   21 12/20/07   12:50:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Because ofthelimitations ofsynthesis, theambiguity diagram hasbeen moreameasure ofthesuitability ofaselected waveform thanameansoffindingtheoptimum waveform. Singlepulseofsinewave.Theambiguity diagram forasinglerectangular pulseofsinewaveis showninFig.11.9.Contours forconstant valuesofdoppler frequency shift(velocity) are showninFig.11.9a.Thecontour forzerovelocity istriangular inshapeandrepresents the autocorrelation function ofarectangular pulsesuchaswouldbepredicted fromEq.(11.52). Contours forfixedvaluesoftimedelayareshowninFig.11.9b.Thecentercontour corre­ sponding toTR=0isthespectrum ofarectangular pulse[Eq.(11.53)]. 
 #&!2 IS USEFUL  EVEN FOR A SYSTEM WITH )& LIMITERS  BECAUSE THERE WILL BE SMALL VARIATIONS ON THE ORDER OF A FEW D"  IN THE COMBINATION OF CLUTTER RESIDUE AND SYSTEM NOISE 4O REEMPHASIZE  HOWEVER  WITHOUT THE LIMITERS  THERE MAY BE TENS OF D"S DIFFERENCE BETWEEN CLUTTER  RESIDUE AND SYSTEM NOISE Ó°£ÎÊ  9   Ê,  
 |  The transmitter is adjusted to broadcast what is  really not a continuous note, but a series of short, sharp ‘pips’ of energy. As each pip goes out into space a circuit linked with the CRT momentarily pulls the spot of light down out of its straight-line path; just as it is Starting on its journey. This happens many times a second, because in sending out radio waves for a radar job we must be careful to keep them in very small bursts or pulses, not lasting more than a few millionths of a: second, The reason for this is that if the pulses lasted- for a longer time they would drown the returning echo. 
 The  airborne radome must be strong enough to form a part of the aircraft structure and usi~ally  must be designed to conform to the aerodynamic shape of the aircraft, missile, or space vehicle  in which it is to operate.  A properly designed radome should distort the antenna pattern as little as possible. The  presence of a radome can affect the gain, beamwidth, sidelobe level, and the direction of the  (7.34)264INTRODUCTION TORADAR SYSTEMS Whenthesecondtermcanbeneglected (aswhenthecorrelation interval issmallcompared to thediameter oftheantennaandthephaseerrorisnottoolarge),thegaincanbewritten G- G -el2_(TCD) 2-(4"l/AI2-oe-PoTe where £.istheeffective reflector tolerance measured inthesameunitsasA;Le.,itistherms surfacetolerance ofashallow reflector (largefocal-Iength-to-diameter ratio)whichwillpro­ ducethephase-front variance,,2.Foragivenreflector sizeD,thegainincreases asthesquare ofthefrequency untiltheexponential termbecomes significant. 
 Figure 10.34 shows two views ofahigh- power hard-tube pulser rated at3Mw and Fig. 10.35 shows alightweight hard-tube pulser built forairborne use. The latter israted at144 kw output atpulse durations of0.5, 1,and 2psec; itemploys acircuit very similar toone given bycombining Figs. 
 POL MODE FOR EACH RESOLVED POINT IN THE SCENE  BUT THE SWATH WIDTH IS SMALLER BY A FACTOR OF TWO #ONSIDERABLE PROGRESS CONTINUES TO BE MADE IN THE DEVELOPMENT OF TOOLS FOR QUANTI 
 This result isaccomplished byvarying theperiod ofinsensitivity ofthe beacon following the emission ofitscoded reply. There isalways a finite minimum time between successive beacon replies; the maximum number ofpossible replies isthus the reciprocal ofthis time. Usually this maximum number istoogreat forsafety unless the“dead” time has deliberately been made greater than itwould naturally be. 
 Therefore, it is usually best to specify that the tube be tested in a way that will ensure proper performance in the system, including ad- equate tolerances on the RF drive. Naturally, the transmitter gain and leveling plan must cover all losses and tol- erances of components between the stages as well as the tube tolerances. It is also feasible to consider passive frequency-shaping networks to compensate for known deviations from flatness in the RF tube characteristics. 
 Next, the repetition frequency was chosen tobeashigh aspossible, consistent with getting areasonable fraction oftheextreme range signals toreturn during the time the receiver ison. Thus the value ofj,=1000 CPS, which was selected, lets the entire return signal into the receiver at r=46.5 miles and none at93miles, sothat at75miles about half is lost. The advantage ofahigh value off, isthereduction innumber of stop bands required inthefilter. 
 OBSERVING 3!2S  INCLUDING THE SIZE AND ASPECT RATIO OF THE ANTENNA  M BY  M   ITS RELATIVELY STEEP ANGLE OF INCIDENCE  ^n    ITS SWATH WIDTH  KM    AND USE OF A LINEAR &- CHIRP  MODULATED PULSE WAVEFORM   COMPRESSION RATIO  3EASAT 3!2S AVERAGE RADIATED POWER WAS RELATIVELY SMALL  7  ALTHOUGH ITS PEAK POWER WAS APPRECIABLE  K7  4HE ANTENNA WAS PASSIVE  CONSISTING OF EIGHT FLAT MICROSTRIP PANELS  RADIATING AND RECEIVING (( POLARIZATION 4HERE WAS NO ONBOARD RECORDER  SO DATA WERE DOWNLINKED  BUT ONLY  OF COURSE  WHEN IN RADIO VISIBILITY OF ONE OF THE FOUR GROUND STATIONS IN THE 5NITED 3TATES  #ANADA  AND THE 5NITED +INGDOM  THAT WERE EQUIPPED TO RECEIVE THE DATA 4ELEMETRY WAS 3ATELLITE3!2 52, #OUNTRY ,AUNCH 2ES M  "AND 0OLARIZATION +ONDOR 
 The Miller circuit isswitched bythedouble-diode clamp Vs,Vi,which inturn iscontrolled bythe cathode-coupled flopover VI, Vj. The latter is automatically terminated atafixed sawtooth amplitude bythe signal passed through the biased diode Vs. The Miller circuit islike that described inconnection with Fig. 
 The final output voltage isthen adirect measure oftheinstantaneous power output ofthei-famplifier. I,et this voltage bedisplayed, asafunction oftime, onanoscilloscope. Figure 245a shows atypical single trace which might heobtained inthis way. 
 CIES AND  -(Z  FOR EXAMPLESWITCHING AS OFTEN AS EVERY ONE OR TWO SECONDS WHILE CONFORMING TO STRICT SPECTRAL EMISSION STANDARDS 3UCH INSTANTANEOUS FREQUENCY CHANGES WOULD PLACE UNACHIEVABLE SWITCHING DEMANDS ON THE HIGH 
 31. Croney. J.. 
 TIME ADAPTIVE CALCULATIONS  AND FILTER WEIGHTING IS APPLIED TO REJECT SOME CLUT 
 §S NONLINEAR CHIRP PULSE THAT PROVIDES COVERAGE TO  NMI 4HE  
 NOISE RECEIVER AVAILABLE BECAUSE SUCH A CHOICE REPRESENTS TOO GREAT A SACRIFICE IN OTHER PERFORMANCE PARAMETERS #OST IS RARELY A CONSIDERATION IN REJECTING A LOWER 
 233–234, February 1968. 25. W. 
 All these characteristics will make the scintillation effect on sliding spotlight mode show different patterns. In this paper, we ﬁrstly introduce the observation geometry of sliding spotlight SAR system in Section 2. Then, in Section 3, the theoretical analysis of scintillation effect is performed based on the reﬁned GAF and TFTPCF model. 
 PLANE  BECAUSE OF THE DOUBLE 
 /  /  _Q 60 / 0  _Q / 0 50 L / CL 40 I  30 I  I Signal known 20 I  I ---Signal known  10 I except for phase  5 I  10-• 10-6 10-e 10-,o I0-12 Probobilify of folse olorrn  2  () 10 ?O 30 40 50 60 70 80 90 100  2t/No  Figure IO.!i Comparison of detection probabilities for signal known completely (coherent detector) and  for signal known except for phase (envelope detector). 386 INTRODUCTION TO RADAR SYSTEMS  more information than either the envelope or the zero-crossings detector, it is not surprising  that the signal-to.,noise.ratio from the coherent detector is better than from the other two. The  improvement in the signal-to-noise ratio might vary from l to 3 dB or more, over the range of  signal-to-noise ratios of interest in most radar applications. 
  
 It is employed in phase-lock servos and phase-monopulse receivers. An IF limiter is sometimes employed prior to doppler filtering to control the false-alarm rate when the clutter echo is stronger than the filter can suppress be- low noise level. This was widely used in early two-pulse MTI, but it has drastic impact on the performance of the more complex doppler filters of modern radars. 
 , vol. 93, pp. 14881-14892, 1988. 
 Rec., Washington, Sept. 19-21, 1983. 12. 
 II-scope. AB-scope modified toincludeindication ofangleofelevation. Thetargetappearsastwoclosely spacedblipswhichapproximate ashortbrightline,theslopeofwhichisinproportion tothesineof theangleoftargetelevation. 
 CHAPTER 17 RADAR RELAY BYL.J.HAWORTH AND G.F.TAPE INTRODUCTION From the standpoint oftheeffectiveness with which aradar collects information, the location ofitsantenna isofsupreme importance. In the useoftheinformation much depends upon the location oftheindi- cators. “Radar relay” isameans forseparating these two components sothat each can occupy themost favorable site orsothat indicators can beoperated atseveral places simultaneously. 
 BASED 3!2 4HESE ARE     3INGLE MONOSTATIC  POLARIZATION   4YPICAL OF ALL DEDICATED SPACECRAFT 3!2S  UNTIL THE LAUNCH OF %.6)3!4  WITH EITHER (( OR 66 POLARIZATIONS 4HIS CUSTOM 
 K.: "CW and Doppler Radars," vol. 7, Artech House, Norwood, Mass., 1978, sec. IV-7, pp. 
 The charge transfer device (CTD) is a sampled-data, analog shift-register that may be used  in MTI processors as delay lines, transversal filters, and recursive  filter^.^^-^' There are two  basic types of CTDs. One is the bucket-brigade device (BBD) which consists of capacitive  storage elements separated by switches. Analog information is transferred through the BBD at  a rate determined by the rate at which the switches are operated. 
 Thus, the beamwidth of the echo response of a flat plate is half the beamwidth of an antenna aperture of the same size. The prominent lobe in the horizontal pattern at 68° is a surface traveling-wave lobe closely related to the one appearing at nearly the same angle in the dipole pattern of Fig. 11.7. 
     7 # ,EE AND - - "ELL  h2APID INTENSIFICATION  EYEWALL CONTRACTION AND BREAKDOWN OF  (URRICANE #HARLEY   NEAR LANDFALL v  'EOPHYS 2ES ,ETT   VOL   ,  DOI ',    2 ! (OUZE *R  3  3 #HEN  7 # ,EE  2 & 2OGERS  * ! -OORE  ' * 3TOSSMEISTER  * ,  #ETRONE  7 :HAO  AND - - "ELL  h4HE (URRICANE 2AINBAND AND )NTENSITY #HANGE %XPERIMENT  2!).%8  /BSERVATIONS AND MODELING OF (URRICANES +ATRINA  /PHELIA  AND 2ITA   v  "ULL  !MER -ETEORO 3OC  VOL   PP n     2 * $ONALDSON  *R  h6ORTEX SIGNATURE RECOGNITION BY A DOPPLER RADAR v  * !PPL -ETEOROL    VOL   PP n    * 7ILSON AND ( 0 2OESLI  h5SE OF DOPPLER RADAR AND RADA R NETWORKS IN MESOSCALE ANALYSIS AND  FORECASTING v %3! *  VOL   PP n    4 &UJITA AND & #ARACENA  h!N ANALYSIS OF THREE WEATHER 
 Onanormal PPI itisdifficult todetermine accurately the direction toatarget whose range isasmall fraction ofthat covered bythedisplay. This difficulty isoften partly overcome byexpanding the zero-range origin ofthePPI into acircle sothat the radius vector tothe echo from a nearby target isgreatly increased. Such anarrangement isknown asan open-center PPI. 
 Mostcalculations forprobability of detection withsignal-to-noise ratioastheparameter applyequally wellwhentheratioof signal-energy tonoise-power-per-hertz isusedinstead.Theradarequation developed inthis chapter forpulseradarcanbereadilymodified toaccommodate CW,FM-CW, pulse-doppler, MTI.ortracking radar.47.56.57 Radarperformance figure.Thisisafigureofmeritsometimes usedtoexpresstherelative performancc ofradar.Itisdefined asthcratioofthepulsepoweroftheradartransmitter to theminimum detectable signalpowerofthereceiver.Itisnotoftenused. Blip-scan ratio,Thisisthesamcasthesingle-scan probability ofdetection. Itpredates the widcspread useofthetermprobability ofdetection andcameaboutbythemanner inwhich theperformance ofground-based search-r.adars waschecked. 
 2.8, it was stated that  the angular pattern of the cross section of targets has a many-lobed structure whose spacings  depend on the size and nature of the target. As the target moves relative to the radar, its aspect  changes and the lobed pattern of the target cross section results in a fluctuating received signal.  These amplitude fluctuations occur at a slow rate, compared with the much higher frequency  fluctuations of the engine modulations mentioned above. 
 86 INTRODUCTION TO RADAR SYSTEMS  greater the range, the greater the echo area illuminated hy the hcam. For extended targets,  therefore, the low-frequency amplifier gain should increase 6 dB/octave. A compromise  between the isolated (12-dB slope) and extended (6-dB slope) target echoes might be a  characteristic with a slope of 9 dB/octave. 
 MASTERS  ALTHOUGH THE ELLIP 
 TICS  CERAMICS  ELASTOMERS  AND MONOLITHIC FOAM 4HE OPTIMUM THICKNESS FOR A SINGLE LAYER IS A MULTIPLE OF A HALF WAVELENGTH IN THE DIELECTRIC MATERIAL AT THE APPROPRIATE INCIDENCE ANGLE  BUT MANY SINGLE 
 This will verify the limits of receiver  functionality. A generator of waveforms with arbitrary variation   of any part of a digitally  created  waveform  fills this need.     . 
 SHIFT ELEMENTS TO ELECTRONICALLY STEER A BEAM  B   OR MAY UTILIZE  TRANSMITRECEIVE MODULES WITH PHASE 
 It  follows that space-based radar sounders must choose a frequency and bandwidth that  balance the often conflicting requirements of penetration, reflectivity, and resolution,  under the constraints of available power and antenna aperture. The space-based radar sounders highlighted in Table 18.9 fall naturally into two  groups: subsurface and atmospheric/ionospheric. It is evident that the subsurface  sounders all are at relatively low frequency, in contrast to the atmospheric sounders at  much higher frequency. 
 2.1 ). This  might represent one sweep of the video output displayed on an A·scope. The envelope has a  fluctuating appearance caused by the random nature of noise. 
 Stepped frequency signal of radar transmission and system parameters setting are as shown in Table 1. Figure 3. Geometric distribution for scattering model of plane point. 
 In one system formula­ tion the range dependence varied as the sixth power instead of the fourth power.50 High peak  power is more important with such targets than is high average power.  Similar techniques have also been proposed for cooperative targets by deliberately pro­ viding the target with a passive transponder employing microwave diodes.49•50  Another related target effect that might be utilized for target recognition is the random  modulation of the scattered signal caused by the modification of the current distribution on  a metal target that results from intermittent contacts on the target.67 This modulation can  be detected by examining the frequency spectrum in the vicinity of the received carrier. The  acronym RA DAM, which stands for radar detection of agitated metals, has sometimes been  used to describe this effect.69  Inverse scattering. 
 Also, when multipath is important, by selecting the radar frequency properly, one might  reduce the jamming power received by being in a null of the jammer transmitting antenna. Chaff might not be as  easy to deploy at the lower frequencies.151 In conclusion, the lower radar frequencies might not be as vulnerable as  one might think by examining the traditional radar equation. ch24.indd   39 12/19/07   6:00:53 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 13.3.2  Automobile Radar System Parameters   13.3.2.1  Coverage   The area in front of the vehicle, which is around 1.5 the breaking distance, is identified as the  collision region.  The neighbouring lanes, left and right, are also considered and the functio n- ing of such a Radar system must also guarantee safety when driving in the curves.  This is  shown for a section of straight road in Figure 13.12. 
 15.12, it should be possible, at least in principle, to replace C(y) directly  by the Fourier transform of W(K) (the inverse of Eq. 15.14 for n = 1), thus providing  a direct functional relationship between the radar cross section and the sea wave spec - trum without the restrictions of a small-amplitude approximation. This cumbersome  approach involves extensive computations even to obtain limited results in individual  cases, as shown in work by Holliday et al.10 In another limiting case, the basic integral formulation of the GBVP is solved in  the optical approximation (large k), resulting in an expression commonly called the  ch15.indd   29 12/15/07   6:17:15 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 5. According to the position of Rnein the sequence Rg, the DEM data corresponding to the element Rnein the sequence DEMs can be found. We named these DEM data as Hne. 
 The wind vector is shown as a red arrow. In Figure 9, the ﬂight and look direction of ERS-2 SAR are indicated by black arrows. The wind vector was identiﬁed and shown as a red arrow. 
 The radar wavelengths are usually too short to be  responsive to these lorig water waves, but the effect of such waves is noted by the tilting  of the snialler water waves which are resonant with the incident radar energy. The tilting  effect of the large waves is especially important at low grazing angles since the grazing arigle  is deterniiried not only by tile arigle the radar energy makes with the mean sea surface, but  also by the angle of the resonant waves that ride on the large wave structure.  1 The composite-model theory of sea clutter seems to account for the experimental results  obtained witti vertical polarization better than with horizotital polarizatio~i.'~ Also, it is tnore  applicable to the midrange of grazing angles than to very low grazing angles or to near nornial  ir~cidcrice. 
 ,Ê " 
 19-27, March 1961. 16. Caspers, J. 
 KILL MISSILE  RADAR  LAUNCHER  AND "ATTLE -ANAGEMENT#OMMAND  #ONTROL  AND #OMMUNICATIONS "-#  SYSTEM 4HE 4(!!$ RADAR SEE &IGURE   IS AN 8 
 J.:" Microwave Homodyne Systems," Peter Peregrinus Ltd., Stevenage, Herts, England, 1978  (an Inst. Elect. Engs. 
 6," 
 The chi-square distribution with m = 1 (Swerling cases 1 and 2) is the Rayleigh, or  exponential, distribution that results from a large number of independent scatterers, no one of  which contributes more than a small fraction of the total backscatter energy. Although the  chi-square distribution with other than m = 1 has been observed empirically to give a reason­ able fit to the radar cross section distribution of many targets, there is no physical scallaing  mechanism on which it is based. It has been said that the chi-square distribution with m = 2  (Swerling cases 3 and 4) is indicative of scattering from one large dominant scatterer togel her  with a colJection of small independent scatterers. 
 Kelleher. and H. P. 
 PENDENT SAMPLES AVAILABLE IN THE DESIRED SPATIAL RESOLUTION CELL AND   THE ANTENNA MUST BE RAPIDLY SCANNED THROUGHOUT THE DESIRED ATMOSPHERIC VOLUME EITHER MECHANICALLY OR ELECTRONICALLY -ECHANICALLY SCANNED SINGLE FREQUENCY STANDARD  WEATHER RADARS USE A LONG DWELL TIME TO ACQUIRE AN ADEQUATE NUMBER OF INDEPENDENT SAMPLES TO ACCURATELY ESTIMATE THE SPECTRAL MOMENT DATA USED FOR METEOROLOGICAL MEASUREMENTS ! LARGE BANDWIDTH SYSTEM EG  PULSE COMPRESSION RADAR  CAN ACQUIRE INDEPENDENT SAMPLES IN RANGE IN A SHORT DWELL TIME THAT CAN BE AVERAGED  THUS REDUCING THE DWELL TIME FOR EACH BEAM AND REDUCING THE TOTAL VOLUME COVERAGE SCAN TIME &AST MECHANICAL SCANNING     DEGSEC  PRODUCES DELETERIOUS SPECTRUM BROADENING EFFECTS  THAT ELECTRONIC STEP  SCANNING EASILY AVOIDS SINCE THE BEAM IS FIXED IN SPACE DURING THE DWELL TIME ! FAVORED APPROACH IS TO UTILIZE  A ONE 
 623-650, May-June, 1968.  89. Levine, D.: "Radargrammetry," McGraw-Hill Book Co., New York, 1960. 
 When only the dominant TE10 mode was taken into account, the null could not be explained. When the TE20 mode (which was only slightly cut off) was taken into ac- count, the null showed up clearly. Since a null in the element pattern indicates in- phase addition of the mutually coupled signals, it appears that the array of open- ended waveguides causes the couplings between elements to have a phase variation corresponding to a velocity slower than that of free space. 
 ÊÊ *- 
 TENTH OF THE FULL 
 5, pp. 3753 – 3756. 183. 
 I. Skolnik, Introduction to Radar Systems , New York: McGraw-Hill, 2001, Fig. 2.6. 
 There are two different types of civilian air-survcillanci.:  radars used by the Federal Aviation Administration for the control of air traffic in thc lJnited  States. One is the S-band 60 nmi airport-surveillance radar (ASR ), Fig. 14.9, which prPvidi.:s  information on aircraft in the vicinity of airports. 
 NOISE RATIO OF STATE 
 Instead of  using two separate radars, the same result can be obtained with one radar which time-shares  its pulse repetition frequency between two or more different values (multiple prf's). The pulse  repetition frequency might be switched every other scan or every time the antenna is scanned a  half beamwidth, or the period might be alternated on every other pulse. When the switching is  pulse to pulse, it is known as a staggered prf. 
 This is the range at which the leakage signal and its  noise components (including microphony and vibration) are found. At greater ranges, where  the target is expected, the effect of the JO Bessel function is to reduce the echo-signal amplitude  in comparison with the echo at zero range (in addition to the normal range attenuation).  Therefore, if the JO term were used, it would enhance the leakage signal and reduce the target  signal. 
 Radar  waves are diffracted around the curved earth in the same manner that light is diffracted by a  straight edge. The ability of electromagnetic waves to propagate around the earth's curvature  by diffraction depends upon the frequency, or more precisely, upon the size of the object  compared with the wavelength. The lower the frequency, the more the wave is diffracted. 
 3  of the signal is the same as the IF midband frequencyhF. The outpul or the envelope detector  has a probability-density function given by9  where lo(Z) is the modified Bessei function of zero order and argument Z. For Z large, an  asymptotic expansion for io(Z) is  When the signal is absent, A = 0 and Eq. 
 ^min The examples of the radar equation given above are useful for rough compu- tations of range performance but they are overly simplified and do not give real- istic results. The predicted ranges are generally overly optimistic. There are at least two major reasons why the simple form of the radar equation does not pre- dict with any accuracy the range of actual radars. 
 Ê 
 SEC. 10,10] LINE-TYPE PULSERS 375 impedance, and the capacity ischosen small enough tobealmost com- pletely charged avery short time after theoscillator draws fullload cur- rent. Adamping network may also beprovided tohelp bring down the trailing edge ofthe voltage pulse and prevent post-pulse oscillations. 
 In this case,  module MTBF need only be 22,000 h to provide 90% confidence that the transmitter  FIGURE 11.2  Common solid-state transmitter configurations may combine many amplifiers in parallel  to a single antenna port ( a), or may use phase-shift elements to electronically steer a beam ( b), or may utilize  transmit/receive modules with phase-shift capability at every element to steer a beam ( c). ch11.indd   4 12/17/07   2:25:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 CHANNEL MONOPULSE  FOR MAIN BEAM NULLING AND TRACK 
 E. K. Livingstone, P. 
 Ocean. Technol. , vol. 
 These kinds of statistics are insufficient to define the requirements for detection and tracking. An example will be given on the basis of a long dwell on a target using a constant frequency. The data will be used to indicate the required dynamic range and pro- cessor size and to show the input of the detection and tracking process. 
 Even ifextreme winds are not encountered, a radome-enclosed antenna has  the advantage that it car1 be rotated wit11 a much smaller motor than if it were outside the  radorne exposed to even normal winds.  Solid reflector surfaces require more drive power in wind than do lattice or tubular  surfaces If tlie exposed antenna is subject to icing that can close the holes of a mesh reflector,  the mectlanical design rliigtit have to be made on the basis of a solid surface anyway. Since the  torque on ari antetitla depends 011 tlie wind direction, it will vary as the antenna rotates. 
 BASED SYS 
 LATE THE MEAN CLUTTER TO A LEVEL BELOW !$ SATURATION TYPICALLY BY THE AMOUNT OF THE EXPECTED CLUTTER FLUCTUATION LEVEL  7ITH #!'#  SENSITIVITY LOSS WILL BE LESS THAN OR EQUAL TO THE CALCULATED WORST 
 SANDWICH  E  MULTIPLE 
 (From Burrows a11d  Attwood' arid Straiton atrd Tolbert.46) . 460 INTRODUCTION TO RADAR SYSTEMS  0.51--,~~ ~~~~200  0.1 100  0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300  Rodar-to-target distance, nmi  (a)  5000  3000  2000  0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300  Radar-to-target distance, nmi  (b) ,,::  u  C  ~  0 !  5 -0  0 a:  N :r  L  ,,::  u  C  (I) :,  0  .f  0  ~  0 a:  Figure 12.lO Attenuation for two-way, radar propagation as a function or range and frequency for (a) zero  elevation angle and (b) S0 elevation angle. (From Blake.•1) . 
 STATE TRANSMITRECEIVE MODULE FOR THE 0!6% 0!73 PHASED ARRAY RADAR v  -ICROWAVE  *OURNAL  PP n  /CTOBER   + ,EE  # #ORSON  AND ' -OLS  h!  K7 SOLID 
 This suggests that a lightweight loaded foam material could be used. Dielectric slabs on the surface of an array can often create surface waves and array blindness. In this case, however, the dielectric constant is quite low. 
 ...592 153 Initial Planning and Objectives 592 15.4 The Range Equation. ,595 155 Choice ofPulse Length .596 15.6 Pulse Recurrence Frequency 598 15.7 Azimuth Scan Rate... ... 
 The radar cross section may be  expressed as a = Vm Lai, where Vm is the volume of the radar resolution cell. The volume Vm  occupied by a radar beam of vertical beam width ¢8, horizontal beamwidth 08, and a pulse  of duration r is approximately  (13.15)  where c = velocity of propagation. In the radar-meteorology literature, the radar pulse-extent I,  (in units of length) is often used instead of er in this equation. 
 TIME APPLICATIONS SUCH AS 24)- AND ARE INADEQUATE FOR SERIOUS RADAR DESIGN  WHICH SHOULD BE BASED ON MEASUREMENTS TAKEN AT THE PROPOSED DEPLOYMENT SITE  BUT THEY CAN BE USEFUL FOR ANSWERING CERTAIN QUESTIONS  SUCH AS h#AN MY SIGNAL BE HEARD AT 8 AND IF SO  AT WHAT 3.2 v &OR CALCULATIONS REQUIRING MODERATE ACCURACY  GEOMETRICAL OPTICS OR VIRTUAL RAY 
 Like VS, HRWS is a high-PRF waveform.  However, linear-carrier FM ranging is used to obtain a range measurement, as described  in Section 4.4. This range measurement comes at the expense of frame time with the  addition of various FM slopes for each dwell. 
  0ROGRAMMABLE #ALCULATOR   .ORWOOD  -!  !RTECH (OUSE  )NC    P   2 % :IEMER AND * ! :IEGLER  h-4) IMPROVEMENT FACTORS FOR WEIGHTED $&4S v  )%%% 4RANSACTIONS  ON !EROSPACE AND %LECTRONIC 3YSTEMS  VOL !%3 
 In addition, because so many radar resolution cells contain useful information, meteorological radars require high-data-rate recording systems and effective means for real-time display.8'9 Thus, while many radar applications call for discrimination of a rela- tively few targets from a clutter background, meteorological radars focus on mak- ing accurate estimates of the nature of the weather clutter itself. This poses some challenging problems for the radar system designer to address. The discussion here will refer to a number of useful texts and references for the reader to use. 
 Dual Polarization/Wavelength Radar.  It is clear that polarimetric doppler  radars provide a significant increase in the useful information that can be obtained  from meteorological targets. The detection of hail and more accurate rainfall esti - mates has primary significance. 
 W.B.,andW.L.Root:"Introduction toRandom SignalsandNoise," McGraw-Hili BookCo..NewYork.1958. 6.Bendat.J.S.:"Principles andApplications ofRandom NoiseTheory," JohnWiley&Sons,Inc.,New York,1958. 7.Helstrom, CW.:"Statistical TheoryofSignalDetection," Pergamon Press,NewYork,1960. 
 Theechofromthegrounddirectly beneath theaircraft is calledtheaitilllde relllm.Thealtitude returnisnotshiftedinfrequency sincetherelative velocity between radarandground isessentially zero.Cluttertoeithersideoftheperpendicu­ larwillhavearelative-velocity component andhencesomedoppler frequency shift;con­ sequently theclutterspectrum fromthealtitude returnwillbeoffinite width.Theshapeofthe. 146 INTRODUCTION TO RADAR SYSTEMS  I J Tronsmitter to receiver leokoge  I  Altitude return 7, , Main-lobe clutter   torg get echo (head-on)  to - 2 ;/A fo + 2v/~  Frequency  Figure 4.36 Portion of the received signal spectrum in the vicinity of rtie RF carrier frequency 11, fur a pul>  doppler AMTI radar. f Afier ~a~uire," Proc. 
 #7 PROBING SCATTEROMETER MEASUREMENTS OF A  CORN PLANT AT  4HE SOLID CURVE IS THE FULL PLANT THE DOT 
 OBSERVING SATELLITE 3!2 STAN 
 SANDWICH   WHICH CONSISTS OF TWO RELATIVELY DENSE THIN SKINS AND A THICKER LOW 
 G. Massey: Tilted Plane Optical Processor, Appl. Opt., vol. 
 20.5«, two complex (/, Q) samples are fully utilized to calculate a complex monopulse ratio statistic. This calculated statistic, the measured monopulse ratio, provides the basis for a computer table lookup of the target angle of arrival relative to the null in the delta beam. The computer lookup function is simply a tabulated version of the assumed monopulse ratio consisting of the assumed delta beam antenna pattern to that of the assumed sum beam ver- sus angle off-beam boresight. 
 The product of p...l  is the effective aperture Ae. A typical reflector antenna with a parabolic shape will produce a  beamwidth approximately equal to  (JO = 65).  l (2.50)  where I is the dimension of the antenna in the plane of the angle 0, and). 
 IEE, pt. III, vol. 93, pp. 
 the proper delay forthe R-sweep, either byinspecting the range scale orbydisplaying onthe A-sweep anelectronic marker which indicates thesetting oftheR-sweep delay. Such anindicator iscalled an“A-and- R-scope.” One form ofdeflection-modulated indicator which deserves special mention istheJ-scope, inwhich thesweep iscircular and thedeflections Transmitted Dulaa Ground FIG.30 S3?I ~ Echo signal 11 ~oRlndex (a)Reading inthousands ofyards. (b)Reading inhundreds ofyards. 
 Some use very wide  bandwidth to obtain fine range resolution to locate sources of scattering.96 Most have  multiple-polarization capability, and some are capable of polarimetry because the  phase of two received signals with orthogonal polarization can be measured.97 The basic elements of an FM-CW scatterometer are shown in Figure 16.20. The  swept oscillator must produce a linear sweep; this is easy with yttrium-iron-garnet  (YIG)–tuned oscillators but requires linearizing circuits if tuning uses a varactor. FIGURE   16. 
 Tests carried out on the Rhine River  had in principle yielded the  usefulness of this method.  . Radartutorial (www.radartutorial.eu)   4    Figure 3: Radar principle  Radar Basic Principles   The electronic principle on which radar  operat es is very similar to the principle of  sound -wave reflection. 
 Aircraft radomes, especially those used at supersonic speeds, are subject to mechanical  stress and aerodynamic heating so severe that the electrical requirements of radomes made of  dielectric materials nitrst be sacrificed to obtain sufficient mecl~anical strength. The radome  RADAR ANTENNAS 267 atransmission lossof0.5dBandcausetheantenna sidelobes toincreaseanaverageof1dBat the-25dBlevel.Theboresight mightbeshiftedlessthan0.1mr-adandtheantenna noise temperature mightincrease lessthan5K.'36Approximate formulas areavailable forpredict­ ingtheelectrical effects(gain.beamwidth. sidelobes, andboresight error)ofametalspace­ frameradome. 
 The Strait of Hormuz (PersianGulf)isparticularlyinterestingasthemonsoontherehastocontendwiththeshamal(anorthwesterlywind)overIraqandthePersianGulffromthenorth.Thestraititselfliesattheboundarybetweenthetwowindsystems;afrontisformed with the warm, dry shamal on top and the colder, humid monsoonunderneath. Consequently, conditions are favorable for the formation of anextensive duct, which is of great importance to radar operation in the Straitof Hormuz. Bay of Bengal (Area 5). 
 Vertical polarization might be preferred when complete vertical coverage is required. Horizon­ tal polarization might be specified when enhanced range capability is desired and complete  vertical coverage is not necessary. The theoretical curves of Fig. 
 Multiple PRFs may be used to move the target with respect to the clutter, thus avoiding completely blind ranges or blind frequencies due to high clutter levels. This relative motion occurs owing to the range and doppler foldover. If one PRF folds sidelobe clutter and a target to the same apparent range and doppler, a sufficient change of PRF will separate them. 
 electronics and redundant gimbal motor windings. The OMV system computer initiates the acquisition-search function to permit detection of a 1-m2 Swerling 1 target at a 4.5-nmi range (with 99 percent probability of detection and a false- alarm rate of one alarm per hour.) Monopulse tracking is performed to within a minimum range of 35 ft. Peak power is programmed over a 50 dB range during the rendezvous maneuver to minimize the RF radiation intensity on sensitive targets. 
 THE 
 TO 
 11.15a ). The frequency increases linearly from f1 to f2 over the duration of the pulse,  Fig. 11.15b. 
 For example, a typical MPRF set  for X band with range-doppler coverage of 150 km–100 kHz is shown in Figure 5.16.  This set is for a 3 ° antenna beamwidth, ownship (i.e., the radar carrying fighter)  velocity of 300 m/s, and an angle off the velocity vector of 30 °. The PRF set is 8.88,  10.85, 12.04, 12.82, 14.11, 14.80, 15.98, and 16.77 kHz. 
 26 of "Radar Handbook," M. I. Skolnik (ed.) McGchw-Hill Book  Company, New York, 1970. 
 Practical Corrections Terrain Height Adjustments. If the height of the target above local terrain is to be obtained, the height relative to mean sea level must be corrected by the height of the terrain below the target. This involves calculation of ground range from target slant range and elevation angle and computer lookup of terrain height versus ground range and azimuth. 
 ING THE RANGE OF THE !$ CONVERTERS    NORMALIZING -4) CLUTTER RESIDUE CAUSED BY SYSTEM INSTABILITIES  AND   NORMALIZING RESIDUE DUE TO THE SPECTRAL SPREAD OF hFIXED CLUTTERv CAUSED BY EITHER SCANNING OR WIND 
 Kept. 3074, Naval Research Laboratory, Washington, June 1975. 2. 
 February, 1948.  51. Baker, C. 
 The amount ofcoupling isusually fixed ata value that gives the best noise figure. This isnecessarily greater than critical coupling, and inthecase ofa6AC7 seems tobeabout transitional —that is,just before adouble hump appears inthe pass band. The bandwidth with this amount ofcoupling depends upon thecrystal resist- ance and the mixer and tube capacities. 
 LENGTH "LASS MATRIX  THE FEED CAN ACTUALLY COMPENSATE FOR THE APERTURE EFFECT  AND PRODUCE A BEAM DIRECTION THAT IS INDEPENDENT OF FREQUENCY (OWEVER  THE MORE CONVENTIONAL FEEDS TEND TO REDUCE THE BANDWIDTH OF THE ARRAY %ND 
 Geosci. 2013 ,58, 126–136. [CrossRef ] 17. 
 The number of lines depends on the degree of phase  quaritization that can be tolerated. The number is limited by the quality of the switches, as  riieastlred by the diuerence between their impedance in the "off" and "on " positions. With  many switches it1 parallel, the "off" impedance of each must be high if the combined im-  pedance is to be large corripared to tlie "on" impedance of a single switch. 
 Electronics 2019 ,8, 287. [ CrossRef ] 25. Yang, J.; Su, W.; Gu, H. 
 The degree of elliptical polarization is often described by  the axial ratio, which is the ratio of the major axis to the minor axis of the polarization ellipse.  Linear polarization is most often used in conventional radar antennas since it is the  easiest to achieve. The choice between horizontal and vertical linear polarization is often left to  the discretion of the antenna designer, although the radar systems engineer might sometimes  want to specify one or the other, depending upon the importance of ground reflections. 
 n°Ó  2!$!2 (!.$"//+  INCREASING THE WAVEFORM PULSEWIDTH WITHOUT EXCEEDING CONSTRAINTS ON TRANSMITTER PEAK  POWER 4HE AVERAGE POWER OF THE RADAR MAY BE INCREASED WITHOUT INCREASING THE PULSE  REPETITION FREQUENCY 02&  AND  HENCE  DECREASING THE RADARS UNAMBIGUOUS RANGE )N ADDITION  THE RADAR IS LESS VULNERABLE TO INTERFERING SIGNALS THAT DIFFER FROM THE CODED TRANSMITTED SIGNAL 4HE MAINLOBE OF THE  COMPRESSED PULSE AT THE  OUTPUT OF THE MATCHED FILTER HAS TIME   OR RANGE  SIDELOBES THAT OCCUR WITHIN TIME INTERVALS OF DURATION  4  BEFORE AND AFTER THE  PEAK OF THE PEAK OF THE COMPRESSED PULSE 4HE TIME SIDELOBES CAN CONCEAL TARGETS  WHICH WOULD OTHERWISE BE RESOLVED USING A NARROW UNCODED PULSE )N SOME CASES  SUCH AS PHASE 
 7.1.3  Range Measurement with CW Radar   Range measurement with CW Radar is only possible over the range of th e uniqueness of the  signal (meaning the range λ/2), however, when in this range, quite exact.  Thus CW Radar is  suitably outstanding for position control and/or range measurement in automatic control eng i- neering.  As an example, the measurement of the wear of a brake disc of a passenger car is represented in Figure 7.6. 
 TO 
 Graham, “Synthetic interferometers for topographic mapping,” Proc. IEEE , vol. 62, pp. 
 (3.12b )l  J,,(up) J,.-J.,  J,,(down) J,. + f4 (3.12a)  (3.12b)  The range frequency fr may be extracted by measuring the average beat frequency; that is,  ![Jb(up) + Jb(down)] J,.. Ir J,,(up) and J,,(down) are measured separately, for example, by  switching a frequency counter every half modulation cycle, one-half the difference between the  frequencies will yield the doppler frequency. 
 Solid circles apply to average  values t 20° around broadside, x's apply to  the avf"tafle' of the ± 20" sector about the  head and the ± 20° sector about the tail.  (Afcer Ho11yhtm1 arui Smith.93) . 510 INTRODUCTION TO RADAR SYSTEMS  19.5 Hz.97 The wing-beat frequency fin hertz and the length I or the wing in millimeters are  found98 to be related byjl0·827 = 572. 
 A cluster of five feeds might also be employed, with the central  feed used for transmission while the outer four feeds are used for receiving. High-power RF  switches are not needed since only the receiving beams, and not the transmitting beam, are  stepped in this five-feed arrangement.  One of the limitations of a simple unswitched nonscanning pencil-beam antenna is that  the angle accuracy can be no better than the size of the antenna beamwidth. 
 However, for the sake of convenience, the impulse response of the  matched filter is sometimes written simply as s(- t).  Derivation of the matched-filter characteristic, The frequency-response function of the  matched filter has been derived by a number of authors using either the calculus of varia-  tions' or the Schwartz ineq~ality.~ In this section we shall derive the matched-filter frequency-  response function using the Schwartz inequality.  I-,  (a)  I I-+ Figure 10.1 (a) Received waveform s(t); (b) impulse response  (b) It(t) of the matched filter. 
 Karelitz, and L.A. Turner (eds.): "Radar Scanners and Radomes," MIT  Radiation Laboratory Series. vol. 
 When the transmitter and receiver are stationary (VY = VR = O), the target's bistatic doppler at the receive site fa is fB = (2WX) cos 8 cos (p/2) (25.17) When p = 0°, Eq. (25.17) reduces to the monostatic case, where 8 is now the angle between the velocity vector and the radar-to-target LOS, which is colinearTARGET . with the bistatic bisector. 
 Earth Sci. 2014 ,72, 677–691. [CrossRef ] 16. 
 SARTs.  Search and Rescue Transponders33 (SART) form part of IMO’s Global  Maritime Distress and Safety System34 (GMDSS). These are 9 GHz radar transponders  that are mainly designed to be used on survival craft (such as life rafts) in emergency  conditions. 
 A. J. Butrica, To See the Unseen: A History of Planetary Radar , Darby, PA: Diane  Publications, 1997. 
 H., and S. J. Schmidt: Gross Errors in Height Indication from Pulsed Radar Altimetas  Operating over Thick Ice or Snow, Proc. 
 3. 4.The minimum range difference atwhich two targets canberesolved vanes directly with pulse length. With al-~sec pulse, aircraft inseparable inazimuth can beresolved ifthey differ inrange by more than 164 ydplus asmall distance which depends onthe characteristics ofthe receiver and the indicator. 
 Moreover, at frequencies above 6 GHz the frequency response is independent of angle, so that D = O. For lower frequencies, the fre- quency response is angle-dependent. For angles less than 20°, only two points were available, 0° and 10°; so sepa- rate frequency regressions were run at each of these angles. 
 2013 ,7, 071598. [ CrossRef ] 2. El-Darymli, K.; Gill, E.W.; McGuire, P .; Power, D.; Moloney, C. 
 5.8, the phase-locked filler, 1 7 or the phase-locked  loop.  If, in any of the above techniques, moving targets are to be dislinguished from stalionary  objects, the zero-doppler-frequency component must be removed. The zero-dopplcr-frequency  component has, in practice, a finite bandwidth due to the finite time on target, clutter tluclua­ tions, and equipment instabilities. 
 109. M. Valeri, S. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 For reference, the two distributions are given78:  p v dvve d v p v dvvv( ) ( ) ( )/ /= =− ψ ψψ 02 01 220 Rayleigh e e Iavv a− +   ( ) /2 202 0 0ψ ψ(sine w ave R ayl + e eigh)  where v = envelope voltage  y0 = mean square voltage  A = sine-wave peak voltage  I0(x) = Bessel function, first kind, zero order, imaginary argument In practice, the distribution from large targets may be more complicated than either  of the simple models described. 
 MONLY ASSOCIATED WITH FIGHTER RADARS 4HERE ARE USUALLY TWO RANGE 
 Woodward-Levinson method. Another method of approximating the desired antenna pattern  with a finite aperture distribution consists in reconstructing the antenna pattern from a finite  number of s,pnpled values. The principle is analogous to the sampling theorem of circuit theory  in which a time waveform of limited bandwidth may be reconstructed from a finite number of  samples. 
   (& /6%2 
 Clutter maps work well for stationary radars operating at fixed  frequencies, but are less effective for other radars. The CA-CFAR is useful, even  for a system with IF limiters, because there will be small variations (on the order of  a few dB) in the combination of clutter residue and system noise. To reemphasize,  however, without the limiters, there may be tens of dB’s difference between clutter  residue and system noise. 
 UP OR (EAD 
 SION ARE IN THE SAME PLANE  n NOSE 
 $   
 J. Martin, and C. Pepe, “Active impedance effects in low sidelobe and ultra  wideband phased arrays,” Proc. 
 Goward: "Aerials for Ccntirnetre Wavelengths." Cambridge University Press.  New York, 1950.  8. 
 The AGC maintains constant angle-tracking sensitivity (volts per  degree error), even though the target echo signal varies over a large dynamic range, by  controlling gain or dividing by Σ . AGC is necessary to keep the gain of the angle-  tracking loops constant for stable automatic angle tracking. Some monopulse systems,  such as the two-channel monopulse, can provide instantaneous AGC or normalizing  by use of log detectors as described later in this section. 
 Predetection integration requires that the phase of the echo signal be preserved if full  benefit is to be obtained from the summing process. On the other hand, phase information is  destroyed by the second detector; hence postdetection integration is not concerned with  preserving RF phase. For this convenience, postdetection integration is not as efficient as  predetection integration. 
 S ECHO IN A  NARROW BROADSIDE SECTOR OF ANGLES 4HE & 
 SHAPING THAT CAN BE USED TO REDUCE BOTH PRECIPITATION CLUTTER AND VERTICAL LOBING EFFECTS (OWEVER  THE RELATIVELY SHORT RANGE OF MOST TARGETS OF REAL INTEREST MEANS THAT THE VOLUME OF THE RADAR 
   NO   PP n    !PRIL  2EPRINTED IN +OVALY   * * +OVALY   3YNTHETIC !PERTURE 2ADAR   .ORWOOD  -! !RTECH (OUSE    4HIS IS A COLLECTION  OF EARLY CLASSIC PAPERS CONCERNING 3!2   $ # 3CHLEHER   -4) AND 0ULSED $OPPLER 2ADAR  .ORWOOD  -! !RTECH (OUSE    . ,EVANON  2ADAR 0RINCIPLES  .EW 9ORK 7ILEY 
 Marth, and J. G. Wall, “The GEOSAT radar altimeter,” Johns Hopkins  APL Technical Digest , vol. 
 TION OF THE TRANSMITTED WAVEFORMS  AND THE RADIATED PULSE TAKES THE FORM OF A hCHIRPv &)'52%    2ADIATED FIELD PATTERN FROM A RESIS 
 M. Thompson, R. J. 
 1)ornh. C'.. arid M. 
 It contains  a licated cathode that generates an electrori beam which strikes a semiconductor diode at high  RADAR TRANSMITTERS 217 technology. Although therehavebeensignificant advances inmicrowave solid-state devices andalthough theypossesspropertles thatdifferfromothermicrowave sources, thedegreeof application ofthesedevicestoradarsystems hasbeenlimited. Microwave transistor.28.35.46AtLbandtheCWpowerthatcanbeobtained fromasingle microwave transistor mightbeseveraltensofwatts.Unlikevacuum tubes,thepeakpowerthat callheachicved withIlarrowpulsewidthsisonlyahouttwiccthcCWpower. 
 L. Jones, and J. W. 
 Rept. PTR-6C, June 25, 1943 (AT1 14009). Reprinted in Proc. 
 PLY SWITCHES IN LENGTHS OF LINE IN BINARY INCREMENTS EG   n  n  AND  n  AND  REQUIRES A SET OF DIODES FOR EACH BIT 4HE DIODES ARE USED AS S WITCHES TO CONTROL WHICH  BITS ARE ACTIVATED TO ACHIEVE A PARTICULAR PHASE STATE 4HE HYBRID 
 TOR FILTER THAT CAN BE IMPLEMENTED WITHOUT MULTIPLIERS 4HESE FILTERS PROVIDE REJECTION IN THE STOPBAND AT FREQUENCIES THAT ALIAS TO THE PASSBAND AS A RESULT OF DECIMATION 3INCE THEY PROVIDE RELATIVELY LARGE PASSBAND DROOP AND SLOW STOPBAND REJECTION  THEY ARE GENERALLY FOLLOWED BY A &)2 FILTER THAT CAN BOTH CORRECT FOR #)# PASSBAND DROOP AND  &)'52%  $IGITAL DOWNCONVERSION ARCHITECTURE    
 / , , I '' :I. ; '• ; ' l .  I= (A¢)2 (4.17) . 
 [\ \] [\}\][\ \] [\ \]  76 22-24 
 SIGMA CONVERTERS DIFFER FROM CONVENTIONAL  .YQUIST RATE CONVERTERS BY COMBINING OVERSAMPLING WITH NOISE 
 The input has a dimension of 224 ×224 = 50176. The output was implemented using the softmax operation and consists of three classes. 2.2.2. 
 Farina, “Combined effect of phase and RGPO delay quantization on  jamming signal spectrum,” Proc. of IEEE Int. Conf. 
 CATION OF ITERATIVE OPTIMIZATION TECHNIQUES IN CONJUNCTION WITH PHYSICAL OPTICSnBASED PATTERN COMPUTATIONS 4HESE ANALYSIS METHODS AND SOFTWARE PACKAGES ARE SUMMARIZED IN 3ECTION  /FFSET 
 The modern integrated avionic suite concept blurs the boundaries  between traditional radar functions and other sensors, countermeasures, weapons, and  communications (see Figures 5.12 and 5.14 later in the chapter). There is a microwave  and RF suite; an electro-optical, infrared, ultraviolet (EO) suite; a stores management  suite; a controls and displays suite; a multiply-redundant vehicle management suite,  and a multiply-redundant processor complex. Each microwave and/or RF aperture may have some embedded signal conditioning  but then may be multiplexed to standardized common design RF, filter, frequency ref - erence, analog to digital conversion (A/D), input-output (I/O), and control modules. 
 PULSE FINITE 
 33935–33950, 2001. 130. L. 
 MeteoroL, vol. 12, pp. 238-244, 1955. 
 19.2 THE RADAR EQUATION FOR  METEOROLOGICAL TARGETS The received power Pr from a radar point target can be derived from any of a variety  of expressions that are applicable to radar in general.23,26,32 For a single point target, a  simple form that is readily derived is  Prr=βσ 4 (19.1) where b is a constant dependent upon radar system parameters (transmitted power Pt,  antenna system gain G, and wavelength l), r is the range to the point target, and s is  the radar cross section (RCS).* It is in the calculation of s for distributed meteorological targets that the radar  equation differs from that for point targets. For distributed targets like rainfall the RCS  may be written  s = hV (19.2) where h is the radar reflectivity in units of cross-sectional area per unit volume and V  is the volume sampled by the radar. h can itself be written as  η σ= =∑ i iN 1 (19.3) where N is the number of scatterers per unit volume and si is the backscattering cross  section of the ith point scatterer. 
 &   &)'52%  !PPROXIMATE -4) IMPROVEMENT FACTOR LIMITATION DUE TO PULSE 
 R.: 7'lic C;eograpliical and Height Distribution of the Gradient of Refractive Index, 1'r.oc.  IRE. vol. 
 (b) Vector diagram of the sum and difference signals.TARGET . by beating two of the signals with the frequency difference between their LOs and the LO of the third signal. The angle-error voltage is then determined by ei- ther a conventional phase detector or simply an amplitude detector.14 The effect of AGC action and normalizing is performed by hard limiting which causes a weak-signal suppression of the difference signal similar to the effects of hard lim- iting on a weak signal in noise.20 FIG. 
 P. Murray, “Electromagnetic compatibility,” Chap. 29 in Radar Handbook , 1st Ed., 1970,  pp. 
 TO 
 Because all these conditions . are not always satisfied, it is common to use the term Z6, the effective reflectivity factor, in place of Z. When Ze is used, it is generally understood that the above conditions are assumed. 
 FORMATION DECISIONS TO REDUCE DEGREES OF FREEDOM ARE DRIVEN BY THE INTERFERENCE RANK FOR THE RADAR PROBLEM /NE CAUTION IN THE DESIGN PROCESS IS THAT IF THE TRANSFORMATION IS FIXED IN THE RADAR DESIGN  IT IS IMPORTANT TO HAVE EXCESS DEGREES OF FREEDOM BEYOND THE TOTAL INTERFERENCE RANK )MPLEMENTATION #ONSIDERATIONS  !S DISCUSSED ABOVE  TRANSFORMATIONS AND TECH 
 288 INTRODUCTION TO RADAR SYSTEMS  {~ <>-0 (}-<'  D u A/16  >..18 \/4  lnd1v1duol  phase bit u  >.12 '  Figure 8.6 Cascaded four-hit digitally  switched phase shifler with A/ 16 quantiza­ tion. Particular arrangement shown gives  135° of phase shift (A wavelength).  of lines and switches required when it is necessary to minimize the quantization error. 
 ORDER FEATURES OF SKYWAVE RADAR SEA 
 The local oscillator uses a Gunn diode or an FET, giving a typical inter - mediate frequency of 60 MHz. Detection and Processing.  After the LNFE, a logarithmic amplifier reduces the  dynamic range of the received signal to prevent limiting. 
 height, ft LRASV forward Operational 34 6.3 2000 Practices 21 5.5 650Trials 17 6.9 1650 SRASV forward Operational 5 5.6 2000 Practices 37 4.3 800 LRASV beam Operational 22 6.9 2300 Practices 19 6.2 700Trials 36 8.0 1700Airborne Maritime Surveillance Radar, Volume 1 2-19. It was concluded the largest swept area was achieved by using the broadside aerials. Better performance than expected was achieved at low altitudes and it was concluded that operation at heights above about 2000 ft would not bring signi ﬁcant beneﬁt. 
 Altitude-Line Clutter Filtering. The reflection from the earth directly beneath an airborne pulse radar is called altitude-line clutter. Because of specular reflection over smooth terrain, the large geometric area, and the relatively short range, this signal can be large. 
 20, pp. 24 and 26, March, 1977.  98. 
 metres, instead of about 14 metres. Radar systems mus:  obviously work to fine limits if any attempt is to be made  to draw a map of the terrain below by means of a con.  centrated beam of energy. 
 The azimuth blanking circuit (v7b, V8,V9)Canalsobereplaced byasimPle cam-and-switch arrangement. Ifthe scanner executes only asector scan, even this isunnecessary. 13.15. 
 LOPE IS 2AYLEIGH DISTRIBUTED AND THE POWER IS EXPONENTIALLY DISTRIBUTED  -ARCUMS MOST IMPORTANT RESULT WAS THE GENERATION OF CURVES OF PROBABILITY OF DETECTION  0 $  VER 
 Some authors2 use a scattering cross section per unit projected area rather than  per unit ground area. Figure 16.2 illustrates by using a side view  the difference  FIGURE   16. 1 Geometry of the radar equation ch16.indd   2 12/19/07   4:54:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Thefirstmicrowave experiments werethoseofHertzin1886.Experiments at6-mmwavelength occurred in1895.80 Intheearly1920s,millimeter-wave research wasreported intheUnitedStates.Germany, and Russia,withwavelengths asshortas0.22mm.81Although manyimportant applications ofthe microwave regionhavebeendeveloped, therehasbeenalmostnocomparable activityinthe millimeter-wave region.Therearemanypossible reasons forthislackofactivity, including lackofadequate millimeter-wave components, smallantenna sizes,anddifficult MTI.But themostrestricting ofallhasbeentherelatively largeattenuations experienced whenpropa­ gatingthrough theclearatmosphere, aswellastheaddedattenuation duringrain.Thelarge attenuations arelikelytolimitmillimeter radartoshort-range applications wherethetotal attenuations aretolerable ortoapplications wheretheatmos'phere isabsent,suchasinspace oratveryhighaltitudes. Millimeter wavelengths mightalsofindapplication whenthepropa­ gationpathdoesnottraverse alargepartoftheearth'satmosphere, aswhenaground-based radardirectsitsenergyatornearthezenith.(At94GHzthetwo-way lossintransiting theentireatmosphere isabout1.7dBatzenith,3.5dBat60°fromthezenith,and10dBat80° fromthezenith.)82 Submillimeter wavelengths.83.84Theadvantages ofhighresolution, widebandwidth, and smallantenna aperture areevenmoreprevalent inthesubmillimeter proportion oftheelectro­ magnetic spectrum thanatmillimeters. Theattenuation intheclearatmosphere, however, is farworsethanatmillimeters andvariesfromabout10dB/kmatI-mmwavelength tomore than1000dB/kmatOJ-mm wavelength. 
  0$     AFTER - 3CHWARTZ  Ú )%%%   &)'52%   #OMPARISON OF VARIOUS DETECTORS IN LOG 
 NOISE RATIO 3.2  AND SPUR 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars.  SPACE-BASED REMOTE SENSING RADARS  18.616x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 mode was designed to measure subsurface horizons in the lunar dielectric constant  in both side-looking and down-looking viewing geometry. The instrument was based  on synthetic aperture radar (SAR) principles. 
 Transmission of long pulses permits a more efficient use of the average power capability of the radar. Generation of high peak power signals is avoided. The average power of the radar may be increased without increasing the pulse repetition frequency (PRF) and, hence, decreasing the radar's unambiguous range. 
 9Classification by Waveform Radars CW Pulsed Noncoherent Coherent Low PRF Medium  PRFHigh PRFFMCW ("Pulse doppler") CW = continuous wave  FMCW = frequency modulated continuous wave  PRF = pulse repetition frequencyNote: MTI                Pulse Doppler      MTI = moving target indicator. 10Plane Waves z1t2txE DIRECTION OF  PROPAGATIONoE oE−λ• Wave propagates in the z direction • Wavelength, λ • Radian frequency ω = 2π f  (rad/sec)  • Frequency, f(Hz) • Phase velocity in free space  is c (m/s) •x-polarized (direction of the  electric field vector) •Eo, maximum amplitude of  the waveElectric field vector. 11Wavefronts and Rays • In the antenna far-field the waves are  spherical • Wavefronts at large distances are  locally plane • Wave propagation can be accurately  modeled with a locally plane wave approximation PLANE WAVE FRONTS RAYSLocal region in the far field of  the source can be approximated by a plane wave ANTENNARADIATION PATTERN DR2(2 / )RDλ >. 
 In spite of it requiring no modulator, dc operation has  seldom been used because of its many limitations.30 Crossed-field amplifiers have been used in radars in the past, but they have signifi - cant disadvantages, as was described in the second edition of this Radar Handbook,   that make it less likely they will be widely used in the future. 10.5 GYROTRONS31,32,33 It has been noted previously that the power handling capability of the microwave  power tubes discussed thus far in this chapter decreases as the frequency is increased.  This results because the resonant structures of the slow-wave microwave circuitry of  these tubes become smaller with increasing frequency. 
 65. Trunk, G. V.: Detection Results for Scanning Radars Employing Feedback Integration, IEEE Trans.,  voi. 
 The transmitter  generates a continuous (unmodulated) oscillation of frequency fo, which is radiated by the  antenna. A portion of the radiated energy is intercepted by the target and is scattered, some of  it in the direction of the radar, where it is collected by the receiving antenna. If the target is in  motion with a velocity v, relative to the radar, the received signal will be shifted in frequency  from the transmitted frequency jo by an amount + fd as given by Eq. 
 W. J. Caputi, Jr., “Stretch: A time-transformation technique,” IEEE Trans ., vol. 
 For a time-delay measurement, k depends on the  shape of the frequency spectrurrl S(f), and M is the rise time of the pulse; for a doppler  frequency rneasurenient, k depends on ttie shape of the time waveform s(t) and M is the  spectral resolution, or the reciprocal of the observation time; and for an angle measurement k  depends on the shape of the aperture illumination A(x), and M is the beamwidth.  Range-accuracy - leading-edge measurement. The measurement of range is the measurement of  t irne delay TR = 2R/c, where c is the velocity of light. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars.  SPACE-BASED REMOTE SENSING RADARS  18.376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 The PRF is 4 kHz, approximately twice that of most conventional altimeters, slightly  larger than the pulse-to-pulse statistical independence condition of 3.75 kHz. 
 STRATE  METAL BASE  ETC  EXHIBITS BOTH A THERMAL RESISTANCE AND A THERMAL CAPACITANCE 4HEN  THERE EXISTS AN EQUIVALENT THERMAL TIME CONSTANT  S  FOR EACH PACKAGING MATERIAL  LAYER 4HIS THERMAL TIME CONSTANT HAS BEEN APPROXIMATEDED  AS   S        &Q#+4(      WHERE & IS THICKNESS CM    Q IS DENSITY GMCC    # IS SPECIFIC HEAT 7SECGM n#   AND  +4( IS THERMAL CONDUCTIVITY 7CMn#  &OR EXAMPLE  &IGURE  SHOWS THAT WHEN THE  PULSE WIDTH AND DUTY CYCLE FOR A GIVEN 'A!S TRANSISTOR IS INCREASED FROM  §S AND  TO  §S AND   RESPECTIVELY  THERE IS A  n# INCREASE IN THE OVERALL JUNCTION TEM 
  
 The variation of the potential  of G3 will in turn change the distribution of currents  between the electrodes (particularly G2 and the anode).  In general it will be found that if G3 is made a little  negative the anode current will be reduced. If less  current flows to the anode there will be more current  available for G2. 
 The output signal spectrum of this pulse shape may not meet spec - tral emissions requirements, and it may be necessary to slow the rise and fall times.  However, the amplifier operating region of optimum efficiency occurs as the tran - sistor is driven into saturation, and for a large transmitter, there may be numerous  tiers of cascaded saturated amplifiers. With so many cascaded saturating amplifiers, it  becomes very difficult to control the rise and fall times as a result of the nonlinearity  that is introduced into the power transfer function for the transmitter. 
 SURFACE FUNCTIONAL  SO THE RADAR ACTS AS A FILTER TUNED TO THE hSPATIAL FREQUENCYv K  COSX   EXTRACTING THAT LINE FROM THE SPECTRUM OF WHATEVER  ASSORTMENT OF SCATTERERS THE SEA SURFACE FUNCTIONAL EXPRESSES  WHETHER THEY BE LONG SWELL COMPONENTS  SHORT 
 In this case it is preferable to define the performance against clutter in terms of the signal-to-clutter improvement (/SCR) versus target doppler shift. This quantity is not included in the IEEE Dictionary,10 but common usage defines the /SCR> at each target doppler frequency, as the ratio of the signal-to-clutter ratio obtained at the output of the doppler filter bank (including all filters) to the signal-to-clutter ratio at the input of the filter bank. It should be noted that the signal-to-clutter improvement of any one filter is equal to the product of the MTI improvement factor of the filter as defined earlier and the coherent gain of the filter at the particular doppler frequency. 
 Thesharp cusp occurring atthe nulls lSee, forexample, Fig.4.2ofVol. 22.. 516 THERECEIVING SYSTEM—INDICATORS [SEC. 
 Ge, L.; Chang, H.-C.; Rizos, C. Mine subsidence monitoring using multi-source satellite sar images. Photogramm. 
 TIES WITH CHARACTERISTIC VELOCITY DISTRIBUTIONS  3OME SMALL 
 I. Katz and L. M. 
 These early radars served quite well the needs of the time and firmly established the utility of radar. Like the HF region, the VHF (very high frequency) region is crowded, band- widths are narrow, external noise can be high, and beamwidths are broad. How- ever, the necessary technology is easier and cheaper to achieve than at micro- wave frequencies. 
 43. Woerrlein, H. H.: Spurious Target Generation Due to Hard Limiting in Pulse Compression Radars,  IEEE Trans., vol. 
 Figure 4.26 shows the improvement factor for a three-pulse canceler and  an eight-pulse filter bank in cascade, as a function of the clutter spectral width. The upper  figure assumes uniform amplitude weighting (- 13.2 dB first sidelobe) and the lower figure  shows the elfect of Chebyshev weighting designed to produce equal sidelobes with a peak value  of -25 dB. It is found that doubling to 16 the number of pulses in the filter bank does not  offer significant -advantage over an eight-pulse More pulses do not necessarily mean  !nore gain in signal-to-clutter ratio, because the filter widths and sidelobe levels change relative  to the clutter spectrum as the number of pulses (and number of filters) is varied. 
             
 510 fl/lf ‘:27k ::lOk Negat,ve tr!gger Input T --OOutput FIG. 13.17 .—Phantastron delay circuit. The cathode-coupled multivibrator can also beused intheform ofa freely running oscillator, aflopover, orascale-of-two, but the Eccles- Jordan form ismost common forsuch purposes. 
 There are two general classes of angel echoes: dot angels, which are point targets due to  birds and insects, and distrihirtrd angels, which have siibstantial horirontal or vertical cxtc~lt  and are due to inhomogeneities of the refractive index of the atmosphere. Birds and insects in  s\\h~ti\ntial nt~mber can also appear as distrihi~tcd ai.rgcls, and can have a dcgracting cfkct on  radar. Since they are moving clutter to an MTI radar they are difficult to remove by dopplcr  filtering. 
 Note that  a conducting reflector will have low return loss whereas a nonconducting reflector  will have a high return loss. In Figure 21.4, the calculation has been derived from  1 meter to 10 meters as the radar range equation is not an accurate model in this  range less than 1 meter. and the purpose of the explanation is to provide a basic  introduction to first order signal estimation. 
 Also, in that month, the first radar measurement of the height of  aircraft above ground was made by measuring the elevation angle of arrival of the reflected  signal. In March, 1936, the range of detection had increased to 90 miles and the frequency was  raised to 25 MHz.  A series of CH (Chain Home) radar stations at a frequency of 25 MHz were successfully  demonstrated in April, 1937. 
 ' -/~re~uene~ agility and glint redu~tion.~~~~~~~' Th e angular error due to glint, which affects all  tracking radars, results from the radar receiving the vector sum of the echoes contributed by  the individual scattering centers of a complex target, and processing it as if it were the return  from a single scattering center. If the frequency is changed, the relative phases of the individual  ( rnonopulse  Receiver noise  (conical scan)  I 1 1 1 11 1111 I 1 1 11 1111 I 1 1 11 111  1 10 100 1,000  Relative radar range  Figure 5.14 Relative contributions to angle tracking error due to amplitude fluctuations, angle fluctua-  tions, receiver noise, and servo noise as a function of range. (A) Composite error for a conical-scan or  sequential-lobing radar; (B) composite error for monopulse. 
 SPACE TRANSFOR 
 The frequency of the local oscillator is generally driven by a  control signal, derived from within the IF amplifier. It includes facilities for manual  frequency control by the operator. The latter can be useful, for instance, when look - ing for SARTs in heavy sea clutter, as it allows returns from own transmissions to be  desensitized. 
 RESOLUTION MAPPING OF THE %- BACKSCATTER  FROM AN OBSERVED SCENE -ORE PRECISELY  THE RADAR DATA IS OBTAINED IN POLAR COORDI 
 LINE CLUT 
 r 1t // 1 It ~ L ‘( e—.! 1 1 I I, FIG, 8.6,—The .$N/UPN-l, aportable bnttery-operated 10-cm beacon.FIG. S..5.-Tbe AN/I’PX-2 beacon The AN/PPN-2 isa1.5-nl beacon de- signed foruseprincipally byparatroops. Such beacons have been used principally toindicate tosupporting aircraft the location ofisolated forward elements onthe ground, such asadvance parties ofparatroops orsecret agents.Figure 8.5shows the AN/PPN-2, a1.5-m beacon carried bypathfinder paratroopers; Fig. 
 TRACKING COORDINATE SYSTEM  DEPENDING UPON THE DIRECTION OF THE INITIAL ERROR THAT MOVED THE SOURCE OFF THE PRECISE ON 
 WATER CONTENT  GM   -AI I.    £  PR   . £°n  2!$!2 (!.$"//+    +M M   
 ESSARY TO PREVENT UNANTICIPATED DEGRADATION OF NOISE FIGURE OR DYNAMIC RANGE  )NADEQUATE DYNAMIC RANGE MAKES THE RADAR RECEIVER VULNERABLE TO INTERFERENCE   WHICH CAN CAUSE SATURATION OR OVERLOAD  MASKING OR HIDING THE DESIRED SIGNALS ! TABULAR FORMAT FOR SUCH A COMPUTATION A TYPICAL EXAMPLE OF WHICH IS SHOWN IN 4ABLE   WILL PERMIT THOSE COMPONENTS THAT CONTRIBUTE SIGNIFICANT NOISE OR RESTRICT THE DYNAMIC RANGE TO BE QUICKLY IDENTIFIED h4YPICALv VALUES ARE INCLUDED IN THE TABLE FOR PURPOSES OF ILLUSTRATION 5NITS )NPUT 34# !TTENUATOR !MPLIFIER "ANDPASS &ILTER -IXER "ANDPASS &ILTER !MPLIFIER !'# !TTENUATOR ,IMITER !$ #ONVERTER #OMPONENT     .OISE &IGURED"         #OMPONENT 'AIN D" 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 14.2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 from truly tactical objects. 
 Peak and Average Power Limitations.  A first-order limit on the RF power out - put capability of a transistor is its breakdown voltage and maximum current handling  capability. Within that limit, the maximum practical level of power output that can be  obtained from a single transistor over a given bandwidth is governed by the thermal  dissipation limit of the device. 
 R.: Monopulse Difference Slope and Gain Standards, IRE Trans., vol. AP- 10, pp. 343-344, May 1962. 
 FREE BANDWIDTH CENTERED AT  ,(    4HE AVAILABLE 2& PASSBAND IS FROM   TO   AND THE CORRESPONDING )& PASSBAND IS FROM  TO  (OWEVER  SPURI 
 (11.50), states that the maximum value of the ambigu­ ity function occurs at the origin and its value is (2E)2. where Eis the energy contained in the  echo signal. Equation ( 11.51) is a symmetry relation. 
 By using a model called Alexnet [ 24], the researchers achieved a remarkable result, which have reduced the error rates of 8.2% in top-one error rates and 8.7% in top-ﬁve error rates than the previous work [ 24,25]. Furthermore, CNNs have achieved many impressive results in computer the vision area, such as handwritten digits recognition [ 26], trafﬁc sign recognition [ 27], and face recognition [ 28]. Deep learning applications in SAR images have been gradually used. 
 Also. the  letter-band nomenclature widely employed by the radar engineer for designating the common  radar frequency bands (such as L, S, and X} has been officially adopted as a standard by the  IEEE.  The material in this book has been used as the basis for a graduate course in radar taught  by the author at the Johns Hopkins ·University Evening College and, before that, at several  other institutions. 
 PLING IS USUALLY PERFORMED AT THE MINIMUM RATE TO MEET THE .YQUIST CRITERIA 3INCE THE BASEBAND  ) AND  1 SIGNALS HAVE BANDWIDTHS "   EQUAL TO HALF THE  )& SIGNAL BANDWIDTH  A SAMPLE RATE JUST GREATER THAN THE )& BANDWIDTH IS REQUIRED SEE &IGURE   &)'52%  "ASEBAND SAMPLING  
  COURTESY OF THE 7HITE 3ANDS -ISSILE 2ANGE AND  ,OCKHEED -ARTIN A   B . 
 W. Hannon: A Cylindrical Phased-Array Antenna for ATC  Interrogation, Mic.rowar-e J., vol. 16, pp. 
           
 The line stretcher is often imple-  niented it1 coaxial line. A tnecliatiical line stretcher that gives niore phase shift for a given  arnoitnt of motion that1 a conventional line stretcher is the helical-line phase shifter due to  Stark.5'." The phase velocity on the helical transmission line is considerably less than tlie  velocity of light. For this reason a given mechanical motion produces more phase change than  would a line stretcher in conventional transmission line. 
 In Proceedings of the Asian-Paciﬁc Conference on Synthetic Aperture Radar (APSAR 2015), Singapore, 1–4 September 2015. 150. Sensors 2019 ,19, 2921 8. 
 In spite of its non- linear characteristic this waveform has retained the good Doppler tole rance of the linear chirp.  . Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  132          Figure 12.28  Compressed output of final pulse compression  system design using 5 -pole  Bessel filter and 360 tap digital FIR filter. 
 217–218, 1951.  7. H. 
 andJ. J.Campbell: Experimental Resultsofthe Complex Indicated AngleTechnique forMultipath Correction. JEEETrailS., vol.A£:S-IO. 
 Oct. 25 28. 1977. 
             .   (& /6%2 
 This is not always a practical technique, however, since the echo-signal  amplitude can fluctuate strongly for reasons other than a change in range. Instead, the range  ambiguities in a multiple prf radar can be conveniently decoded and the true range found by  the use of the Chinese remainder theorem4' or other computational algorithms."  2.1 1 ANTENNA PARAMETERS  Almost all radars use directive antennas for transmission and reception. On transmissiol~, tllc  directive antenna channels the radiated energy into a beam to enhance the energy con-  centrated in the direction of the target. 
 D. Steinberg, “Chapters,” Chaps.1–4 in Modern Radar: Analysis, Evaluation, and System  Design , R. S. 
 Therearcatleastthreetechniques whichmightbe usedtominimize theeffectofspherical aberration. Oneistoemployareflector ofsufficiently largeradiussothattheportion ofthesphere isareasonable approximation toa paraboloid.3032Thesecondapproach istocompensate forthespherical aberration with specialfeedsorcorrccting lenses.33.34Thesetechniques yieldonlyslightlylargerscanangles thanthesingleparaboloid reflector withmovable feed. i\.thirdtechnique toapproximate thespherical surfaceandminimize theeffectsofspheri­ calaberration istostepaparabolic reflector asshowninFig.7.15.7.35.36 Thefocallengthis reducedinhalf-wavelength steps,makingafamilyofconfocal paraboloids. 
 20. Ig. The V-beam radar has been referred to as a 3D radar by some authors.3'7'10 Technically, however, it should not be classified as a true 3D radar because it lacks resolution in the elevation dimension. 
 Forthisreason,therangecellssurround­ ingthetestcellareoftenomitted whenaveraging the background. Asmentioned inSec.5.10, theresolution oftargetsinrangeisdegraded bytheadaptive threshold process. Theabovedescription ofthecell-averaging CFARassumed thatthebackground from whichthethreshold wassetwasdetermined bysampling inrange.Inthoseradarswhich extractthedoppler frequency shift,aswithabankofdoppler filters,theestimate ofthe background fanbebasedonboththerangeandthedopplerdomains.77Itisalsopossible to utilizedatafromtheadjacent angle-resolution cellstoestablish thethreshold. 
 The number of  zeros of the adaptive MTI section is again determined by the required improvement  factor and the expected spectral spread of the clutter. The phase shift is applied to the  input data in the form of a complex multiply, which again requires the transformation  of the phase angle into rectangular coordinates. This transformation can easily be  performed by a table lookup operation in a read-only memory. 
 ON ASPECT OUT TO  ON EITHER SIDE OF THE TARGETS VELOCITY VECTOR 3IMILARLY  #ASES  THROUGH  SHOW CONDITIONS WHERE THE TARGETS SPEED IS     AND  TIMES THE RADARS SPEED  IN WHICH CASE THE TARGET CAN BE SEEN CLEAR OF SIDELOBE CLUT 
 8.6 FEEDS FOR  If a single transmitter and receiver are utilized in a phased array, there must be some form of  network to connect the single port of the transmitter and/or the single port of the receiver to  each of the antenna elements. The power divider used to connect the array elements to the  single port is called an array feed. Several examples of such networks for linear arrays where  shown in Figs. 
 £Ç°ÓÈ  2!$!2 (!.$"//+  )N ADDITION TO THIS ECHO  THE PIXEL CONTAINING THE TARGET WILL PRODUCE AN ADDITIONAL ECHO  WITH A PERIODIC PHASE ERROR   FP LPF PEODFT FT   SIN   SIN  VIB VIB   7E ASSUME  O  D  K  THUS EO   4HE NORMALIZED COMPLEX ECHO CORRESPONDING  TO THE PHASE ERROR IS   EEJJ F TEFF P  SIN  VIB      y JF TFPSIN  VIB             
 In this application, a pencil beam is scanned in elevation by use of  frequency and scanned in azimuth :by mechanical rotation of the entire antenna.  Linear array with phase scan., Electronic phase steering, instead of frequency scanning, in the  3D air-sur,veillance radar is generally more expensive, but allows the use of the frequency  domain for purposes other than beam steering. The linear array configuration is also used  to generate multiple, contiguous fixed beams (stacked beams) for 3D radar. 
 EFFICIENCY 0!%  OF  AT  6 AND  '(Z ON A  MM &%4  AND #7 POWER OF  7 AT  6 AND  '(Z ON A SINGLE  MM TRANSISTOR    POWER DENSITY  OF  7MM AT  '(Z   LESS THAN  D" POWER DEGRADATION AFTER   HOURS   2& OPERATION AT  6 WITH CHANNEL TEMPERATURES OF  n# 0OWER 
 Skolnik, M. I.: private communication, September 1986. 33. 
 For  hemispherical phased array coverage, the maximum scan angle can be upwards of   ± 60°, depending on the number of array faces used in the system configuration. Thus,  for an X-band array that requires scanning to large angles, the spacing between radiat - ing elements, and by implication, the maximum spacing available for T/R modules  when they are aligned behind the radiating elements must be on the order of 0.5 inches  or less. Alleviations in packaging may be allowable if the scan volume is not required  to extend to a full field of view. 
 Thereisnotheoretical limittothebandwidth ofaButlerarrayexceptforthebandwidth associated withthehardware makingupthenetwork, whichcanbegreaterthan30percent. Theyhaveevenbeenconstructed withbandwidths ofseveraloctaves.94Operating overtoo wideaband,however, changes thebeamwidth, shiftsthelocation ofthebeams,andcan introduce gratinglobesjustaswithanyotherarrayantenna. Thecomplexity oftheButlerbeamforming network increases withthenumberofele­ ments.A64-element network, forexample, requires 192directional couplers and160fixed­ phaseshifters. 
 Resolution and Contrast.—In order todistinguish between objects oramong different parts ofthe same object itisnecessary that they beresolved. The characteristics ofthe receiving equipment which influence resolution are the bandwidth ofthe signal channel, which affects range resolution, and thespot size and scale factor ofthedisplay, which also affect range resolution and toalesser extent angular resolution aswell. Since factors concerned with thedisplay areleast under control, and since their limitations often fixthe limit ofusefulbandwidth, they will bediscussed first. 
 Prop­ erly calibrated, the automatic gain control setting is a  measure of the backscatter coefficient at the surface that,  in turn, is dependent on wind speed.  In summary, the altimeter provides three basic mea­ surements with precisions specified as  1. Height: 3.5 centimeters for 2 meters significant  wave height (SWH),  Johns Hopkins APL Technical Digest, Volume 8, Number 2 (1987) . 
 M. Spetner: Phenomenological Vector Model of Microwave Reflection  from the Ocean, I RE Trans., vol. AP-4, pp. 
 Finally, sample-and-hold circuits must be added in AFC, AGC, and angle track loops. Either the conventional or the inverse receiver can be made to operate in the sampled-data mode. Sampled data can be used all the way to intercept or as a midcourse mode for an active terminal seeker. 
 We have already marked off a scale of miles above the  line of light, so by reading the number of miles opposite  the echo blip we can tell instantly how far away is the  aircraft. Think back for a moment, and you will realize  that there are two processes going on here simultan-  eously. There are the radio pulses being shot out into space at a speed of roughly 186,000 miles a second, and if an aircraft or a ship is 186 miles away, then we shall find that the pulse goesoutand-echoes back in #4ysecond. 
 LAYER MIRROR GRID CONFIGURATION /N 
 Middleton: A Theoretical Comparison of the Visual. Aural, and Meter  Reception of Pulsed Siprials in tlie Presence of Noise, J. Appl. 
 RATIONS FOR A VERY COMPACT COMPARATOR 4HE PERFORMANCE OF THESE AND OTHER SIMILAR FOUR 
 T .. W. H. 
 AGILE RADARS AND ON MOVING PLATFORMS EG  RADARS ON SHIPS   THEY ARE NOT NEARLY AS EFFECTIVE IN THESE ENVIRONMENTS 4ARGET 2ESOLUTION  )N AUTOMATIC DETECTION SYSTEMS  A SINGLE LARGE TARGET WILL PROB 
 J. Res. Nat. 
 The surrounding reference cells are then used to estimate the unknown  parameters, and a threshold based on the estimated parameters is obtained. The sim - plest adaptive detector, shown in Figure 7.12, is the cell-average CFAR (constant  false-alarm rate) investigated by Finn and Johnson.21 If the noise has a Rayleigh den - sity, p(x) = x exp ( −x2/2s2)/s2, only the parameter s (s2 is the noise power) needs to  be estimated, and the threshold is of the form T = KΣxi = Knπ σ/2ˆ, where ˆσis the  ch07.indd   11 12/17/07   2:13:11 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 A. W. Rudge, K. 
 TION 4HE BEAMS ALL LIE IN ONE PLANE 4HE SYSTEM MAY BE COMBINED WITH MECHANICAL ROTATION OF THE ANTENNA  GIVING VERTICAL 
 43. Sensors 2019 ,19, 2764 We deﬁned the azimuth mainlobe as the part of the azimuth proﬁle (see Figure 4b) in which the energy exceeds−4 dB (where the maximum value of the azimuth proﬁle is normalized to 0 dB). Setting 10 log⎭parenleftBig sin c2⎭parenleftBig y/prime 0/ρa⎭parenrightBig⎭parenrightBig =−4, (13) yields y/prime 0≈0.5ρa. 
 A novel adaptive wide-angle SAR imaging algorithm based on Boltzmann machine model. Muldimens. Syst. 
 ABLE ILLUMINATION FUNCTION THAT PROVIDES  LOW SIDELOBES AT A MINIMUM LOSS IN GAIN &OR  LOW 
 Sensors 2019 ,19, 2921 E  Tz' Figure 7. The model of interferometric ArcSAR. Then, we can acquire the complex conjugate result of G 1and G 2: G2G∗ 1=E2 sexp⎭parenleftbigg −j4π λRsp2⎭parenrightbigg ·exp⎭parenleftbigg j4π λRsp⎭parenrightbigg =E2 sexp⎭parenleftbigg j4π λ⎭parenleftBig Rsp−Rsp2⎭parenrightBig⎭parenrightbigg (22) According to Equation (22), the interferometric phase p1can be expressed as: p1=4π λ⎭parenleftBig Rsp−Rsp2⎭parenrightBig (23) Based on the work in [ 22], plane wave approximation is used to simplify the derivation process. 
 One ofrthe first techniques for achieving frequency-agile magnetrons was known as spin-  trtrrirrg. or rotary ttcrring. In this device a rotating slotted disk is suspended above the anode  resonators. 
 BAND  LOW 
 PULSE BINOMIAL 
 Understanding of the global climate requires that quantitative measurements of precipitation be made throughout the world, particularly in the tropics and over the oceans. Satellite observations ap- pear to offer the only practical mechanism for obtaining these measurements. Meneghini and Atlas79 describe a concept for a dual-wavelength radar for precip- itation measurements from space. 
 220. Sensors 2019 ,19, 743 Figure 7. Leveling data versus SBAS-InSAR method plots of land subsidence. 
 BASED DUCTS /VER THE OCEAN AND NEAR LAND MASSES  WARM  DRY CONTINENTAL AIR MAY BE ADVECTED  OVER THE COOLER WATER SURFACE %XAMPLES OF THIS TYPE OF ADVECTION ARE THE 3ANTA !NA OF SOUTHERN #ALIFORNIA  THE 3IROCCO OF THE SOUTHERN -EDITERRANEAN  AND THE 3HAMAL OF THE 0ERSIAN 'ULF 4HIS ADVECTION WILL LEAD TO A TEMPERATURE INVERSION AT THE SURFACE )N ADDITION  MOISTURE IS ADDED TO THE AIR BY EVAPORATION  PRODUCING A MOISTURE GRADIENT TO STRENGTHEN THE TRAPPING GRADIENT 4HIS TYPE OF METEOROLOGICAL CONDITION ROUTINELY LEADS TO A SURFACE DUCT CREATED BY A SURFACE 
 The most common element lattices have either a rectangular or a triangular grid. As shown in Fig. 7.8, the mnth element is located at (mdx, ndy). 
 The helical scan and the nodding scan can both be used to obtain hemispheric coverage  with a pencil beam. The nodding scan is also used with height-finding radars. 'The Palmer,  spiral, and raster scans are employed in fire-control tracking radars to assist in the acquisition  of the target when the search sector is of limited extent. 
 E. Rittenbach, “Clutter attenuation analysis,” US Army  Electronics Command, Fort Monmouth, NJ, Report No.ECOM-2808, March 1967.  9. 
 TEROMETER IN THE !-) SUITE )T COVERS SWATHS ON BOTH SIDES OF THE SATELLITE GROUND TRACK 4HE NEAR EDGE OF THESE  
 89. Moody. H. 
 However, RMA requires interpolation and is computationally intensive, which can cause real-time processing difﬁculties. Figure 17shows a multi-angle fusion result of two views in a large scenario area, in which red represent the components of forward-looking view and green represent the components of 22. Sensors 2019 ,19, 1701 backward-looking view. 
 BEAM CLUTTERe   ! POSSIBLE EXCEPTION TO THIS IS SHIPBORNE (& SURFACE 
 2013 ,10, 845–849. [ CrossRef ] 25. Pu, W.; Li, W.; Wu, J.; Huang, Y.; Yang, J.; Yang, H. 
 ,-lppl. Phys., vol. 25,  pp. 
 (The two are  related, however.) It is seen that actual clutter has a greater probability of a large value of sea  clutter than does· Rayleigh clutter~Statcd in other terms, the actual distribution has higher  "tails" than the Rayleigh.,This means that clutter seen by a high-resolution radar will have a  greater likelihood of false alarm' than ·.Rayleigh clutter if the receiver. is designed in the . a,  C 05  04  0.3  02  01  g 005  <IJ u  >< i O O?  >-0 01  ii 0005  0 E 0002  a._ 0 001  0005 RADAR CLUTIER 479  l.og ·normol  Clutter cross section in dB lo on arbitrary scale  Figure 13.5 Experimental statistics of vertical polarization, X-band sea clutter for two sea states. 
 Figure 5. Two defocused ships detected in a TerraSAR-X image (sub-images of ship01 and ship02). The red rectangles are the zoomed sub-images. 
 Computer Codes for Reflector Design and Analysis.  A number of commer - cial and university codes have been developed for the analysis and design of reflec - tor systems. Two of the more well-known and commonly used codes are GRASP  and the SATCOM Workbench with its NEC-REF module. 
 An indication of direction (left or right) could also be displayed on the height tube. This was achieved by taking the video output from the radarand feeding it back to the Lucero receiver. Here the signals were switched so that signals from the left-hand antenna de ﬂected the height tube trace to the left and signals from the right-hand antenna de ﬂected signals to the right. 
 J. Schmugge, “Effect of texture on microwave emission from soils,” IEEE Trans. , vol. 
  D" 4HEN   -33,    
 The penalty for this solution is a loss in the  peak antenna gain that can be achieved. An illustration of this approach is provided  in Figure 2.98, which shows both the ARSR-2 antenna pattern and the corresponding  free-space coverage. FIGURE 2.98  Antenna elevation pattern for the ARSR-2 antenna:  (a) compared with the cosecant-squared pattern and ( b) free-space  coverage diagram ch02.indd   98 12/20/07   1:52:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 When integration is not perfect, as is always the case practically, if the value of D0 used in the range equation is based on perfect integration, an imperfect- integration loss factor or factors must be included in the system loss factor L, as discussed in Sec. 2.7. Although the full benefits of predetection integration are realizable only for nonfluctuating targets, some benefit can be achieved by predetection integration of a moderate number of slowly fluctuating targets. 
 6806, November 1968. 26. G. 
 THAN 
 PULSE BASIS AND CAN SUPPORT PULSE REPETITION FREQUENCIES UP TO  K(Z  4HE HIGH VOLTAGE SOLID 
 Theappearance ofthethreetargetsonanA-scope is sketched inFig.2.26h.Themultiple-time-around echoesontheA-scope cannotbedistin­ guished frompropertargetechoesactually withinthemaximum unambiguous range.Onlythe rangemeasured fortargetAiscorrect; thoseforBandCarenot. Onemethodofdisting.uishing multiple-time-around echoesfromunambiguous echoesis tooperate withavarying pulserepetition frequency. Theechosignalfromanunambiguous rangetargetwillappearatthesameplaceontheA-scopeoneachsweepnomatterwhether the prfismodulated ornot.However, echoesfrommultiple-time-around targetswillbespread overafiniterangeasshowninFig.2.26c.Theprfmaybechanged continuously within prescribed limits.oritmaybechanged discretely amongseveralpredetermined values.The numher ofseparate pulserepetition frequencies willdependuponthedegreeofthemultiple­ timetargets.Second-time targetsneedonlytwoseparate repetition frequencies inordertobe resolved. 
 QUENTLY SPECIFIED BY THEIR TRANSFER FUNCTION ( Z  OR IMPULSE RESPONSE HN  +EY  PASSBAND CHARACTERISTICS ARE INSERTION LOSS  BANDWIDTH  PASSBAND AMPLITUDE  AND PHASE RIPPLE  AND GROUP DELAY "ANDWIDTHS ARE FREQUENTLY SPECIFIED IN TERMS OF A  D" BANDWIDTH HOWEVER  IF A LOW PASSBAND VARIATION IS REQUIRED  THE SPECIFIED .   2!$!2 2%#%)6%23   È°ÓÇ BANDWIDTH MAY BE  FOR EXAMPLE  SPECIFIED AS A  D" OR  D" BANDWIDTH 0ASSBAND  AMPLITUDE VARIATION RELATIVE TO THE INSERTION LOSS IS A KEY PARAMETER THAT HAS POTENTIAL IMPACT ON RANGE SIDELOBES AND CHANNEL 
 CANT CROSS 
 1. Provide a response of -66 dB in the clutter rejection notch (relative to the peak target response) of the moving-target filters. 2. 
 archrieflydescribed below. AirTrafficCOlltrol (ATC).Radarsareemployed throughout theworldforthepurpose of safelycontrolling airtrafficenrouteandinthevicinityofairports. Aircraftandground vehicular trafficatlargeairports arcmonitored bymeansofhigh-resolution radar.Radar hasbeenusedwithGCA(ground-control approach) systems toguideaircrafttoasafe landinginbadweather. 
 Gao, M.L.; Gong, H.L.; Chen, B.B.; Li, X.J.; Zhou, C.F.; Shi, M.; Si, Y.; Chen, Z.; Duan, G.Y. Regional land subsidence analysis in eastern beijing plain by insar time series and wavelet transforms. Remote Sens. 
 Three main approaches—adaptive thresholding, nonparametric detectors, and clutter  maps—have been used to solve the noncoherent, false-alarm problem. Both adaptive  thresholding and nonparametric detectors are based on the assumption that homo - geneity exists in a small region about the range cell that is being tested. The adap - tive thresholding method assumes that the noise density is known except for a few  unknown parameters (e.g., the mean and the variance). 
 20.1 Early radar height finding techniques, (a) Method of multipath nulls, (b) Am- plitude comparison using multipath lobes. erator would keep the antenna boresighted on the target with a handwheel while monitoring the target return strength. It was quickly learned that maximizing the signal strength of a target echo in a beam was not sensitive enough to provide the desired accuracies, and so alternative techniques were ultimately developed for this purpose. 
 PEAK  % FIELD !NOTHER  CONSIDERATION IS THAT THE  
 ( b) Pixel B of a vehicle. ( c) Pixel C of the top-hat. 257. 
 BASED SUBREFRACTIVE LAYERS MAY DEVELOP DURING THE NIGHT AND EARLY MORNING HOURS 4HESE LAYERS ARE CHARACTERISTICALLY CAUSED BY ADVECTION OF WARM  MOIST AIR OVER A RELATIVELY COOLER AND DRIER SURFACE 7HILE THE  . GRADIENT IS GENERALLY MORE  INTENSE THAN THAT DESCRIBED ABOVE  THE LAYER IS OFTEN NOT AS THICK 3IMILAR CONDITIONS MAY ALSO BE FOUND IN REGIONS OF WARM FRONTAL ACTIVITY. 
 If a radar is capable of good range-resolution it is also capable of good range  accuracy.  Cltarer red11ctio11. A short pulse increases the target-to-clutter ratio by reducing the clutter  contained within the resolution cell with which the target competes. 
 The half-power beamwidth in the plane of scan  increases as the beam is scanned off the broadside direction. The beamwidth is approximately  inversely proportional to cos 00, where 00 is the angle measured from the normal to the  antenna. This may be proved by assuming that the sine in tile denominator of Eq. 
 This relationship yields the non -calibrated RCS of the measuring objects.  With the  VNwa principle it is important that the obtained phase information remains and the crucial noise bandwidth for the sensitivity is determined by t he narrow filter width of the IF stage (in  the order of a few kHz) and not by the full measuring bandwidth (typically some GHz).   In principle the RCS measuring system is a CW Radar, however with substantially extended abilities. 
 11.29 RCS of a cone frustum, horizontal polarization. (Copyright 1966, IEEE.38) of the incremental length diffraction coefficient. Extending the example provided by Ufimtsev, he devised a set of diffraction coefficients for arbitrary directions of incidence and scattering. 
 MATED  RESPECTIVELY  AS   00 . N ++0 . 
 SIZE DISTRIBUTION CAN BE ATTACHED TO RAIN OF A GIVEN RATE OF FALL  2ESULTS OF THIS STUDY ARE SHOWN IN 4ABLE   WHICH GIVES THE PERCENTAGE  OF TOTAL VOLUME OF RAINFALL OCCUPIED BY RAINDROPS OF DIFFERENT DIAMETERS AND VARYING RAINFALL RATES MILLIMETERS PER HOUR  )N THE BASIS OF THESE RESULTS  THE ABSORPTION CROSS SECTION OF DIFFERENT RAIN RATES IS SHOWN IN 4ABLE  4HIS TABLE GIVES THE DECIBEL ATTENUATION PER KILOMETER FOR DIFFERENT RAINFALL RATES FOR RADAR WAVELENGTHS BETWEEN  AND  CM &)'52%     4HEORETICAL RAIN ATTENUATION IN D"MILE STATUTE   VERSUS RAINFALL RATE AFTER * 7 2YDE AND $ 2YDE  . £°£ä  2!$!2 (!.$"//+  3INCE THE TOTAL 
  AND EXOCLUTTER MOVING TARGETS  AND MISSILES OR BULLETS %ACH CLASS OF RETURN  BASED ON ITS RANGE AND DOPPLER LOCATION  IS SEPARATELY TRACKED AND GEOLOCATED  4HERE ARE SEVERAL COMMON TYPES OF GEOLOCATION MANY OF THEM ARE BASED ON USING  EITHER $4%$ OR CARTOGRAPHIC DATA /NE METHOD USING CARTOGRAPHIC DATA IS SHOWN  &)'52%  -ULTIREGION '-4 THRESHOLDING #OURTESY 3CI4ECH 0UBLISHING  .   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°{£ IN &IGURE  !N ERROR ELLIPSE AND ITS CORRESPONDING ECCENTRICITY ARE CALCULATED FOR  EACH TARGET )F THE ECCENTRICITY IS LESS THAN SOME ARBITRARY THRESHOLD EG   RELA 
 Large antennas must be used since the radar ranges are significantly greater than usual and the prime power in the radar is limited. The vacuum of space and the zero-g environment permit the deployment of antennas with low mass per unit antenna area. Antennas with large diameters, up to 1 km, have been discussed by United States developers.40"^8 In the U.S.S.R., antennas with diameters in the 1- to 10-km range have been discussed.49 In addition to being large and deployable, the SBR antenna must maintain its desired shape whether it be parabolic or planar. 
 AGE 4HE HIGHER THERMAL CONDUCTIVITY OF 3I# ENABLES MORE EFFICIENT THERMAL MANAGE 
 BASED DUCT. 
 LAW DETECTION  THE POST 
 Thegainofconventional pulsedcrossed-field amplifiers istypically between 10and 17dB.Bydesigning thecoldcathode asaslow-wave circuitandintroducing theRFdriveat thecathode emitting surfaceitself,ithasbeenpossible toachieveabout30dBofgainina high-power pulseCFAwithpower,bandwidth, andefficiency commensurate withconven­ tionaldesigns.43TheRFoutputistakenfromtheanodeslow-wave circuit.Thk:;typeofdevice hasbeencalledacathode-driven CFA6orahigh-gain CFA.19 Thetypeofcrossed-field amplifier principally considered inthissectioncanbedescribed asadistributed emission, oremitting sole,amplifier withareentrant, circular formatutilizing aforward-wave interaction without feedback. (Theelectron streamisdebunched toremove themodulation beforereentering theinteraction space.)ThereareothertypesofCFAs, however. TheAmplitron, oneofthefirstsuccessful CFAs,issimilartotheaboveexceptit employs abackward-wave interaction withfeedback. 
 POSITION MODULATION02&  PULSE REPETITION FREQUENCY07-  PULSE 
                         
 W.L.Gamble. andR.L.Hartman: SubmiJlimeter Research: i\ Propagation Bibliography, U.S.Arm.vMissileCommand. Redstone Arsenal. 
 CIERS #OUNTRIES SUCH AS "RAZIL GRACED WITH TROPICAL FORESTS RELY ON SPACE 
 TO 
 MTR-2762, AFAL -TR-73-334, January 1974. 110. J. 
 TIONS FOR AN AIRBORNE SEARCH RADAR .   '2/5.$ %#(/  £È°£Ç )N PRACTICE  ANTENNA BEAMS ARE NOT RECTANGULAR 4HE RESULT IS T HAT THE DOPPLER SPEC 
 The diameter ofthe circle described bythe center ofthe beam ischosen with this application inmind; itis commonly such that the intensity radiated tothe center ofthe circle is somewhat greater than half thepeak intensity. The scan rate isusuallY atleast 1200 rpm. 9.7. 
 This makes it difficult to achieve extremely  low sidclobes. In practice. the sidelobe level of a Luneburg lens seems to be in the vicinity of20  to22<lB. 
 THE ELECTRONICALLY STEERED PHASED ARRAY ANTENNA IN RADAR 299  The phase difference between two adjacent elements in the series fed arra) of Fig. 8.14 is  <P = 2rrf l/v = 2rr//). (8.16)  where f = frequency of the electromagnetic signal  I= length of line connecting adjacent elements (generally greater than the distance  between elements)  r· =-:: velocity of propagation in the transmission line  )_ = wavelength  For convenience of analysis, the velocity of propagation is taken to be equal to c, the velocity  of light. 
 Thus, we next transform the DEM image on the slant range to the ground range. Finally, with the assist of the DEM image on the ground range, the target in the scenes can be imaged on its actual height. The proposed method does not rely on external DEM data. 
 These two components are compensated by two different  techniques.  Ari MI'] radar on a movitig platforni is called AMTI. Altliougli the "A" originally stood  for airhorr~e, the term is now often applied to an MTI radar on any moving platform. 
 When the incident wave is planar and the direction of interest is back toward the source, the geometric optics RCS is simply (T = Tta\a2 (11.12)4s/X FIG. 11.23 Broadside RCS of a per- fectly conducting cube (s = edge length). (Copyright 1985, IEEE.26} . 
 RADAR SCANNING PATTERNS We have seen that although afew radars have been designed with radiation beams that arefixed indirection, the great majority ofradar beams aremade toscan. The motion ofthebeam maybe thought ofas the motion ofapoint onasphere that iscentered atthe scanner. The beam sweeps over acertain region onthesphere determined bytheopera- tional function ofthe radar; often itdoes soperiodically, and inaset geometrical pattern termed the “scan.” The great variety ofscans may bedivided into two categories, simple and complex. 
 Cumming, I.G.; Wong, F.H. Digital Processing of Synthetic Aperture Radar Data: Algorithms and Implementation ; Artech House: Norwood, MA, USA, 2005. 2. 
 VERTICAL DATA  #ALIBRATION OF THE SYSTEMS WAS GOOD  BUT THE ANTENNA EFFECT  DISCUSSED IN 3ECTION  MAKES THE VALUES FROM  TO  LOW %FFECTS OF 2OUGHNESS  -OISTURE #ONTENT  AND 6EGETATION #OVER  3CATTERING  FALLS OFF MORE RAPIDLY WITH ANGLES FOR SMOOTH SURFACES THAN FOR ROUGH SURFACES 3INCE THE ROUGHNESS THAT AFFECTS RADAR MUST BE MEASURED IN WAVELENGTH UNITS  A SURFACE SMOOTH AT LONG WAVELENGTHS MAY BE ROUGH AT SHORTER ONES 4HIS IS ILLUSTRATED IN &IGURE     WHICH SHOWS THESE EFFECTS WITH MEASUREMENTS FROM PLOWED FIELDS !T  '(Z  THE SIGNAL CHANGED  D" BETWEEN  AND  FOR THE SMOOTHEST FIELD AND ONLY  D" FOR THE ROUGHEST !T  '(Z THE SMOOTHEST FIELD WAS ROUGH ENOUGH TO REDUCE THE VARIATION TO  D" &OR MOST SURFACES  CROSS 
       \   ;     \   KKK K K K429H 8 TT 
 MENT  THESE SYSTEMS HAVE AN INHERENT LOW COST OF OWNERSHIP .ORTHROP  'RUMMAN  #ORPORATION  0HASED  !RRAY  2ADARS  #OURTESY  OF  .ORTHROP 'RUMMAN #ORPORATION  !7!#3 !IRBORNE 7ARNING AND #ONTROL 3YSTEM     4HE !IRBORNE 7ARNING  AND #ONTROL 3YSTEM !7!#3  PROVIDES ALL 
 BAND FREQUENCIES  SO THE GENERAL BEHAVIOR OF SEA CLUTTER  IN THIS ANGULAR REGIME  REMAINS UNCERTAIN. 
 Frank Codes.  The Frank code corresponds to a stepped-phase approximation of  an LFM waveform.31 Here, the pulse is broken up into M groups, each of which is  further broken up into M subpulses. Hence, the total length of the Frank code, is M2,  with a corresponding compression ratio of M2. 
 This approach gives IMO an indefinite period to assess the impact of the new regu - lations on the detection of targets in sea clutter before deciding what should happen  with radar, racons, and SARTs at 9 GHz. Another major change in the requirements of older standards is that all new radars  must include provision to display Automatic Identification System (AIS) targets and  that their related information can be accessed on the radar display. The requirements  for target tracking has also had a major revision, with automatic tracking facilities  being required for all radars. 
 SIDED BANDWIDTH  BOTH POSITIVE AND NEGATIVE FREQUENCIES  OF A SIGNAL THAT  IN GENERAL  IS COMPLEX WITH A REAL SIGNAL AS A SPECIAL CASE )S THE TWO 
 43–61, 2003. 51. C. 
 The primary exception is the antiship missile, which uses radar guidance and may be surface- (as well as air-) launched.4'5 The main users of radar guidance are the air defense systems—surface-to-air or air-to-air. These also can employ IR or laser radars, but we shall restrict our discussion to the microwave radar category. Air- to-surface systems for use against ships, armored vehicles, or hard fixed targets The author is indebted to the many colleagues at Raytheon who reviewed various sections of this chapter and especially to David Barthuli, John Curley, and Al Williams for their many valuable com- ments and suggestions. 
 The radar frequency is usually affected by  many things, including the availability of allowed frequencies at which to operate.  The radar frequency might be the last parameter of the radar to be selected—after  many other compromises have been made. ch01.indd   23 11/30/07   4:34:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 405 11.5 Duplexing and TR Tubes. 407. CONTENTS xv MICROWAVE COMPONENTS OFTHE RECEIVER 411 11.6 The Mixer Crystal .....................412 11.7 The Local Oscillator ....................414 11.8 The Mixer ........ 
 REPETITION FREQUENCY IS NOT INCREASED 3UCH A hDUAL 
 Digital Image Processing , 3rd ed.; Prentice-Hall: Upper Saddle River, NJ, USA, 2006. 28. Aharon, M.; Elad, M.; Bruckstein, A. 
 To achieve RF  impedance element  Energy  source  /  Charging path ' L~ircharge path Figure 6.12 Simple representation of a  crossed-field amplifier. (From Cla~~l-  pittV6 Electronic Progress, Raytheitt.)  RADAR TRANSMITTERS 209 Thecrossed-lick! amplifier isbased 011tilesameprinciple ofelectronic interaction astile magnetron. Thus,itscharacleristicsresemble 1110seof themagnetron, andmanyCFAsare cvensimilarinphysical appearance toamagnetron. 
 Two-pass InSAR : ● No special hardware is required; a conventional SAR may be flown twice over the  designated terrain. ● Motion compensation is challenging; the position of the antenna versus time in each  pass must be known with great precision. ● A long baseline (vertical distance between antenna paths) provides fine vertical  resolution (but challenging ambiguities). 
 297-301, April, 1965.  30. Andrews, (i. 
 ABILITY 4HERE IS NOT ONE TRANSISTOR TYPE OR ONE SEMICONDUCTOR MATERIAL THAT IS UNIVER 
 APERTURE PRODUCT /NE CAN OBTAIN A LONG RANGE BY HAVING A  LARGE ANTENNA  A LARGE TRANSMITTER  OR A COMBINATION OF BOTH )T IS NOT USUAL  UNDER MOST CIRCUMSTANCES  FOR A RADAR TO HAVE A HUGE  COSTLY ANTENNA AND A SMALL  INEXPENSIVE TRANSMITTER  OR VICE VERSA 4HERE HAS TO BE A REASONABLE BALANCE BETWEEN THESE TWO MAJOR SUBSYSTEMS OF A RADAR )N A SURVEILLANCE RADAR  STRAIGHTFORWARD CALCULUS WILL SHOW THAT UNDER SIMPLE ASSUMPTIONS THE MINIMUM TOTAL COST OF A RADAR OCCURS WHEN THE COST OF THE TRANSMITTER EQUALS THE COST OF THE ANTENNA BUT THIS IS TRUE ONLY WHEN THERE ARE NO CRITERIA  OTHER THAN MINIMUM COST  THAT HAVE TO BE SATISFIEDAND THERE ARE USUALLY OTHER CRITERIA THAT NEED TO BE CONSIDERED  !S IS WELL KNOWN IN RADAR  THE DOPPLER EFFECT IS EXTENSIVELY USED TO DETECT MOVING  TARGETS IN THE PRESENCE OF LARGE CLUTTER ECHOES )T IS THE BASIS FOR SEVERAL OF THE CHAPTERS IN THIS (ANDBOOK 3OME TRANSMITTER TYPES  HOWEVER  ARE FAR BETTER THAN OTHERS WHEN THE RADAR HAS TO EMPLOY THE DOPPLER 
 Ornstein, and M. C. Licitra, Millimeter Radar for Low-Angle Tracking, IEEE  EASCON '74 Record, pp. 
 For example, a wind speed of 5 kt might be reported  with waveheights of 6 ft, or 20-kt winds with 2-ft waves. These pairings are not  consistent with the values for an equilibrium sea described in Table 15.1 and indicate  the unnoticed or unrecorded presence of heavy swell or highly nonequilibrium wind  conditions or both. Even with all the variables properly specified, recorded clutter  data can be spread over a wide dynamic range, especially at low grazing angles. 
 N.J.,1961. 68.Hoare,E.,andG.Hine:Servomechanisms, chap.11of"Mechanical Engineering inRadarand Communications," C.J.Richards (ed.),VanNostrand Reinhold Co.,NewYork,1969. 69.Plowman, J.c.:Automatic RadarDataExtraction byStorageTubeandDelayLineTechniques, J. 
 TION IS THE SHIFT OF THE ELECTRICAL AXIS  WHICH IS CRITICAL FOR TRACKING RADAR  4RANSMISSION  LOSS IS THE MEASURE OF ENERGY LOST BY REFLECTION AND ABSORPTION 4HE  REFLECTED POWER  CAUSES ANTENNA MISMATCH IN SMALL RADOMES AND SIDELOBES IN LARGER RADOMES 2ADOME DESIGN IS A SPECIALIZED ART  AND MANY BOOKS   ARE DEVOTED TO ITS INTRICATE  DETAILS 4HIS SECTION MAKES NO ATTEMPT TO PROVIDE RADOME DESIGN  INFORMATION AS SUCH  BUT INSTEAD IS AIMED AT MAKING THE RADAR SYSTEM DESIGNER AWARE OF THE BASIC CONCEPTS BEHIND THE TYPES OF RADOMES AVAILABLE FOR VARIOUS APPLICATIONS 4HREE GENERAL CLASSES OF RADOME ARE OF INTEREST FOR REFLECTOR ANTENNA APPLICA 
 Theazimuth beamwidth is1.6°andthevertical beamwidth is4°with cosecant-squared shaping from6°to30°.Beingatransportable equipment. theantenna is self-erecting andisstowedinsidetheshelterthrough aroofhatch.Theradarsystemprovides coverage to60nmiand40,000feetwitha15rpmrotation rate. (7.28).6.. 
 PARAM 
 Frazer, and M. D. Turley, “STAP for Clutter and Interference Cancellation  in a HF Radar System,” IEEE Int. 
  @ 2  OCCURS AT THE TARGET RANGE  WHICH IS OFFSET IN FREQUENCY FROM THE )& CARRIER FREQUENCY BY @  2S2  
 Smaller size means that a tube cannot dissipate heat as well as a larger  tube, so that the power capability of microwave power tubes decreases approximately  inversely as the square of the frequency. The gyrotron, on the other hand, does not have  this type of frequency dependence since it uses what is called a fast-wave  structure.  This is usually a smooth waveguide or a large resonator. 
 Furthermore, there must be no obstructions in the vicinity of the antenna that can divert  energy to the sidelobe regions and appear as high sidelobes. A low sidelobe antenna might  have to be 20 to 30 percent larger than a conventional antenna to achieve the same beamwidtll.  Aperture efficiency. 
 When c-wsignals are used, the various components ofthe scanner data can bedistinguished from one another bysending each onaseparate subcarrier, orbyusing a different audio frequency foreach signal and transmitting them together onasingle subcarrier. The geometrical quantities transmitted canbechosen invarious ways, depending ontheapplication. The most important are: 1.Changes inthe orientation ofthe scanner can betransmitted by means ofawave train inwhich one cycle represents anadvance of the scanner through agiven small increment ofangle. 
 Another delay-line arrangement that isfeasible but hasnotseen field service isthemercury tank. Aquartz plate oscillating inalarge volume ofmercury will generate a“free-space” beam whose width can becal- culated from diffraction theory. Ifsuch abeam isincident upon awall ofthemercury container, itcan bespecularly reflected without appreci- able loss, providing theangle ofincidence issufficiently large. 
 Conf. Proc. Aeronaut, Electronics  (Dayton. 
 ANCE  OF THE STRONG RETURN FROM NADIR  MODEST RANGE RESOLUTION  AND RELATIVELY NARROW FIELDS OF VIEW 4HESE REQUIREMENTS LEAD TO HIGH POWER RADARS AT + U BAND OR ABOVE  A  SIMPLE PULSE WAVEFORM  AND SUBSTANTIAL ANTENNA AREA 2ADAR SOUNDERS SHOULD NOT BE CONFUSED WITH PASSIVE  MICROWAVE RADIOMETERS ALSO CALLED SOUNDERS  UNFORTUNATELYTHAT ARE USED BY OPERATIONAL METEOROLOGICAL SATELLITES TO ESTIMATE ATMOSPHERIC WATER DISTRIBUTION ! MULTIFREQUENCY RADIOMETER GENERATES COARSE WATER VAPOR DENSITY PROFILES FOR WHICH ALTITUDE IS A FUNCTION OF FRE 
 ................................ ...........  5  PULSE WIDTH ................................ 
 Proc. SPIE 2008 ,6970 .[CrossRef ] 16. Odendaal, J.W.; Joubert, J. 
 I I I ( IKONl('Al I Y SII.1 RI.1) l'flASI:11 ARRAY ANII NNA IN RAlJAH 295  Flux driveJ4 The toroid, or twin-slab. ferrite phase shifter may be operated in an analog  fasliiori t~y varying tlic crirrcnt of tlic drive pulse so as to provide different values of remanerit  rnagneti;l.atio~i. .l'liis is called ,fltr.u dr.ir-c~. 
  .EXT 
 T. Ulaby et al., “1-35 GHz microwave scatterometer,” Proc. IEEE/MTT-S 1979 Intl. 
 BAND FREQUENCIES  TYPICALLY 5(&  , BAND  AND INTO 3 BAND 4HESE DEVICES   ARE USUALLY MANUFACTURED AS DISCRETELY PACKAGED TRANSISTORS AND REQUIRE EXTERNAL IMPEDANCE 
 ARRAY  WHERE WI IS THE TAPERING WEIGHT IN THE ANALOGUE LAYER OF &IGURE &)'52%  %XAMPLE OF A 5,! WITH SUB 
 IRE,  vol. 40, pp. 1223-1231, October, 1952. 
 Most passive bistatic radar (PBR) concepts  and developments exploit commercial broadcast transmitters as their source of radar  illumination. FM and High Definition (HD) TV terrestrial broadcast transmitters are  particularly attractive due to their high-power, noise-like waveforms, and relatively  wide bandwidths.49–51 When these broadcast transmitters are appropriately sited and  operating, they can support many types of surveillance, particularly air surveillance,  which is often restricted for monostatic radars operating at VHF/UHF. The surveillance  can be covert because even the transmitter is unaware it is being exploited and can be  counter-stealth due to unavoidable aircraft resonances in the VHF/UHF region. 
 A tapped delay  Tllf.rUTTRONICAl.l.Y STEERED PHASED ARRAYANTENNA INRADARJOJ thetotalangular coverage. Thehandwidth t\f~,ofthesefiltersisdetermined bythefrequency changeneededtoscantheantcnna bcamonebealllwidth, thatis .til" elfA Nil=dOoOR=dOoD(X.22) \\herc (//1=heamwidth and/)=aperture dimension. Substituting Eq.(X.18)intotheabove gIves fcos00 t1fn=.f~(tjd)(Djc)(8.13) ThetimeIIIforthesignaltotransitthesnakefeedfromoneendtotheotherisequalto (l/d)(D/c). 
 Although TNC works only in a single unambiguous  range interval, it is said that it should be able to operate with some medium PRF  radars if significant clutter is not likely to extend over more than one PRF interval.   ch10.indd   20 12/17/07   2:19:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Some caution isnecessary inthe interpretation ofsuch displays; bright radial lines areoccasionally caused bydirectionally selective reflection from a mass ofbuildings with parallel surfaces. Such lines appear tomove along N FIG. 3.33.—Outer harbor, Boston, Mass. 
 4.2 if the antenna pattern is known in the lower hemisphere. In preliminary  system design, the exact gain function may not be known, so one useful approximation  is that the sidelobe radiation is isotropic with a constant gain of GSL. Sidelobe Discretes. 
 corresponds to 11 = + 0.443n: and {) _ lo 11 = -0.443n. The sin O -sin 00 term in the expres­ sion for 11 can be written 1 7  sin O -sin 00 = sin (0 -00) cos 00 -[1 -cos (0 -00)) sin 00 (8.11)  The second term on the right-hand side of Eq. (8.11) can be neglected when 00 is small (beam  is near broad side), so that  sin O -sin 00 ~ sin (0 -00) cos 00 (8.12)  Using the above approximation, the two angles corresponding lo the 3-dB points of the  antenna pattern are  . 
 Thetransmitter, receiver, duplexer, andphaseshiftersforeach elementofthearrayantenna canbeincorporated intoasingleintegrated package, ormodule. Although therehasbeenmuchdevelopment workinsolid-state phasedarrayswitheach element fedbyitsownintegrated module, thisapproach usuallyresultsinacosl1yand complex system.Thishastended,inthepast,toweighagainstthewidespread liseofsuch phased-array radarswhenthenumberofelements islarge. Thecombining ofthepowerfromalargenumber ofindividual solid-state devices is attractive whenusinganarrayantennasincethepoweris..combined inspace,"ratherthanby alossymicrowave network. 
 In the alternate $degree azimuth intervals another 10 pulses are transmitted at  a different prf to eliminate blind speeds and to unmask moving targets hidden by weather.  Changing the prf every 10 pulses, or every half beamwidth, eliminates second-time-around  clutter returns that would normally degrade an MTI with pulse-to-pulse variation of the prf.  A block diagram of the MTD processor is shown in Fig. 
 Itisoftenusedinpropagation workinsteadofnbecause itisamoreconvenient unit.The primedifference between opticalandmicrowave refraction isthatwatervaporhasanegligible effectontheformer;consequently thesecondtermofEq.(12.9)maybeneglected atoptical frequencies. Sincethebarometric pressure pandthewater-vapor contentedecrease rapidly withheight,whilethetemperature Tdecreases slowlywithheight,theindexofrefraction normally decreases withincreasing altitude. Atypicalvalueoftheindexofrefraction nearthe surfaceoftheearthis1.0003.Inastandard atmosphere theindexdecreases attherateofabout 4 x10-8m-1ofaltitude. 
 ION AND ELECTRON 
 TER IS WHEN THE RADARS HAVE A REDUCED PROBABILITY OF DETECTION SO THERE ARE POTENTIAL GAPS  IN THE DATA STREAM OR PERIODS WHERE THE DATA STREAM IS SPARSE )N THESE CASES  A MUCH MORE ACCURATE TRACK STATE CAN BE CALCULATED USING MULTIPLE DATA STREAMS THAN USING ONLY ONE BECAUSE MULTIPLE STREAMS WILL TEND TO FILL IN THE GAPS IN DETECTION AND RESTORE A HIGH CON 
 Stankwitz, H.C.; Dallaire, R.J.; Fienup, J.R. Nonlinear apodization for sidelobe control in SAR imagery. IEEE T rans. 
 The thin dielectric cylinder has been used to model the target support lines sometimes employed in RCS measurements.5 Note that the ^-polarized echo is barely 6 dB less than that for E polarization for this particular dielectric constant. The thin wire (a metal dipole) can have a complicated pattern, as shown in Fig. 11.6. 
 Any use is subject to the Terms of Use as given at the website. The Radar Transmitter. 10.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 Since the magnetron is an oscillator with a random starting phase on each pulse, it can - not be used to eliminate second-time-around clutter echoes—as can an amplifier trans - mitter. Similarly, combining the power outputs of multiple magnetrons has not been  attractive. 
 Sensors 2019 ,19, 1529 T able 6. The simulation parameters of Figure 14. Parameters V alues Radar look direction 180◦ Incidence angle 25◦ Radar frequency C-band Polarization HH Platform height 800 km Platform velocity 7455 m/s Wind direction 45◦, 135◦, 225◦, 315◦ Wind speed 6 m/s Rotation direction of current ﬁeld counterclockwise Maximum Current velocity 1 m/s ȱ (a)ȱ (b)ȱ ȱ (c)ȱ (d)ȱ Figure 14. 
 G. Kim, Z. F. 
 CLUTTER RATIO OBTAINED  AT THE OUTPUT OF THE DOPPLER FILTER BANK TO THE SIGNAL 
 Similarly. it is fouiid that tile use of a criterion which maximizes the clutter attenuation (ratio  of iili'i~t cluttcr power to tllc output clutter power) is also well approximated by a transversal  filter with binomial weights of alternating sign when the clutter spectrum can be represented  by a gairssian function whose spectral width is small compared to the pulse repetition  frequency.' Tlius the delay line cancellers with response sin" nfd Tare "optimum" in the sense  that they approximate the filters which maximize the average signal-to-clutter ratio or  the average clutter attentuation. It also approximates the filter which maximizes the probabil-  ity of detection for a target at the midband doppler frequency or its  harmonic^.^  In spite of the fact that such filters are "optimum" in several senses as mentioned above,  they do not necessarily have characteristics that are always desirable for an MTI filter. 
 The phase at each element is therefore 9, + t~4, where ttr = 0, I, 2, . ,  (N - I), and 4, is any constant phase applied to all elements. The norrnalizetl radiation  pattern of the array when the phase difference between adjacent elements is 9 is given by  sin2 [Nn(tl/l)(sin O - sin no)] G(B) = N~ sin2 [n(rl/l)(sin O - sin 001  The maximum of the radiation pattern occurs when sin 0 = sin OO. 
 §S  PULSEWIDTH IN THE SPECTRAL ANALYSIS PROCESSING IS   $2C "      MS -(ZMM  #OBRA $ANE 7IDEBAND 0ULSE #OMPRESSION 3YSTEM  4HE CHARACTERISTICS OF THE  WIDEBAND PULSE COMPRESSION SYSTEM DEVELOPED FOR THE #OBRA $ANE  RADAR ARE SUM 
 PULSE COMBINA 
 S. Sidhu, “Electromagnetic scattering from a layer of vegetation: a discrete  approach,” IEEE Trans. , vol. 
 § ©¨¶ ¸·; = S B AA B4r 
 Because of the exponential relation between the  false-alarm time and the threshold level [Eq. (2.26)], a slight change in the threshold can cause  a significant change in the false alarm time. In practice, therefore, it may be necessary to set (tit:  threshold level slightly higher than calculated so as to insure a tolerable false alarm time 111  the event of circuit instabilities. 
 Schwartzni;~n. L.. and J. 
 554 1NTRODUCTION TO RADAR SYSTEMS  Figure 14.12 Geometry of a bistatic radar.  ,o many separated receivers are employed with one transmitter, the radar system is called n~ltlrr- *%  static. Some of the characteristics, capabilities, and limitations of the bistatic radar w~ll be ,?  described in this section and compared with the more usual monostatic radar. 
 /- 3YSTEM )NSTABILITIES  .OT ONLY DO THE ANTENNA MOTION AND CLUTTER SPECTRUM AFFECT  THE IMPROVEMENT FACTOR THAT IS  ATTAINABLE  BUT SYSTEM INSTABILI TIES ALSO PLACE A LIMIT ON  -4) PERFORMANCE 4HESE INSTABILITIES COME FROM THE STALO AND COHO  FROM THE TRANS 
 10, pp. 204–221, 1953. 44. 
 Aswas explained ;nSec. 2.9, a reduction inpulse power, accompanied byacorresponding increase in pulse length and decrease inreceiver bandwidth, leaves the maximum range ofaradar system unaffected. Proceeding toalimit inthis direc- tion, imagine thepulse tobemade solong that itfills thewhole interval,. 
 LEVEL ATMOSPHERIC FEATURES THAT ARE DEEMED CRITICAL FOR THE AVIATION  WEATHER FORECASTING  TRANSPORTATION  AND LOCAL EMERGENCY RESPONSE USERS 4HE #!3! RADARS CAN COMMUNICATE WITH EACH OTHER FOR COLLABORATIVE USE OF THE DATA AND ADAPTIVELY CHANGE THEIR OPERATING PARAM 
 The spacing between the individual antennas in the interfer­ ometer system corresponds to the separation between frequencies in the multiple-frequency  distance-measuring technique. The minitrack system is an example of an interferometer in  which angular ambiguities are resolved in a manner stmilar to that described.64  The multiple-frequency CW radar technique has been applied to the accurate measure­ ment of distance in surveying and in missile guidance. The Tellurometer is the name given to a  portable electronic surveying instrument which is based on this principle.57-59 It consists of a  master unit at one end of the line and a remote unit at the other end. 
 BY 
 32, no. 3, pp. 1455–1467, 1997. 
 When the angle variation is not too large, and the rotation vector is sufﬁciently stable during radar imaging, the range Doppler (RD) algorithm is applied for reforming SAR or ISAR images with high accuracy after motion compensation. The polar grid in the spatial frequency domain can be taken as a nearly regularly sampled rectangular grid with no need for interpolations. The main advantage of this method is the low amount of computation and it is the reason why it has been employed in many references [ 26,29]. 
 HS, as we shall see later in this book, is the true  ‘television’ of radar, showing in an aircraft at night or  in fog a picture of the unseen ground over which it is flying. H2S made the ruins of Berlin and Hamburg its monuments, and now has beneficial peacetime applica-  tions in map-making of the new world. A. 
 Updating existing tracks with associated detections. 4. New track formation using unassociated detections. 
 NEUTRAL COLLISIONS THAT ARE FREQUENT AT THESE MODERATE ALTITUDES WHERE THE NEUTRAL SPECIES DENSITY IS STILL RELATIVELY HIGH )T IS NOT REPRESENTED EXPLICITLY IN SOME IONOSPHERIC MODELS WHERE ITS EFFECTS ARE ACCOUNTED FOR WITH AN EMPIRICALLY DERIVED PATH 
 Inaddition tothe fact that inalong line even amoderately low standing-wave ratio can cause instability yinthemagnetron, theextra junctions, bends, and elbows needed foralong line are themselves likely toadd tothe mismatch. Furthermore, asseen from Table 11”1, ther-fattenuation inalong line, particularly atthe higher microwave frequencies, results inthe loss of several decibels when two-way transmission isconsidered. The shortest possible r-fline isrealized bymounting the magnetron ontheback oftheantenna reflector (“back-of-the-dish system”). 
 TION IN ONE PLANE BUT ALLOWS THE USE OF A LINEAR ARRAY IN THE OTHER PLANE  THEREBY ALLOWING FLEXIBILITY IN EITHER STEERING OR SHAPING OF THE BEAM IN THAT PLANE )F BEAM SHAPING NOT SCANNING  IS THE GOAL  AN ALTERNATIVE METHOD USING A SINGLE FEE D  IN LIEU OF A LINEAR ARRAY   IS SHOWN IN &IGURE C  3HAPING OF THE SURFACE ALONG THE VERTICAL AXIS IS USED TO SPOIL  THE BEAM SHAPE IN THIS PLANE  BUT BECAUSE ONLY THE PHASE OF THE  WAVE ACROSS THE APERTURE  IS CHANGED  THERE IS LESS CONTROL OVER THE BEAM SHAPE THAN IN THE PARABOLIC ANDOR PHASE CYLINDER SHOWN IN &IGURE B  WHEREIN THE LINEAR ARRAY MAY BE ADJUSTED IN AMPLITUDE 6ERY OFTEN THE RADAR DESIGNER NEEDS MULTIPLE BEAMS TO PROVIDE INCREASED COVERAGE  OR TO DETERMINE ANGLE &IGURE  D SHOWS HOW MULTIPLE DISCRETE FEED LOCATIONS PRO 
 There aretwo reasons forthis: (1)fre- quency modulation of~he magnetron owing tovariations ofcurrent during thelong pulse can lead toaspectrum wider than theoretical; and (2)itisdifficult tomake apractical AFC that will hold asetintune toa small fraction ofamegacycle persecond. Nod-cpower supplies areprovided inther-fhead, except fortheTR- tube keep-alive supply. This isasmall half-wave supply with resistance- capacity filter, located under thereceiver chassis. 
 M HEIGHT RESOLUTION IN ALTIMETER MODE  AND  n# IN RADIOMETER  MODE !LL -AGELLAN DATA ARE AVAILABLE THROUGH THE 0LANETARY $ATA 3YSTEM  #ASSINI  A MULTIMODE RADAR MAPPER LEVERAGED FROM  -AGELLANS HERITAGE  WAS  INCLUDED IN THE  
 Range ghosts occur if the correlated range does not represent the  true target range and typically occur when there is more than one detection per look.  Range ghosts can also occur if a target detection on a single look correlated with other  dissimilar target(s), or if multiple range correlations occurred on a set of detections  corresponding to a single unique target (i.e., multiple unfolded ranges fell within the  correlation window). One method for efficiently scanning and correlating the unfolded detections  involves coarse binning , as shown in Figure 4.18. 
 A breaking wave, with plumes of water cas - cading down its face and perhaps a halo of spray above, is only one of the rich assort - ment of scattering elements appearing on the sea surface—including wedges, cusps,  microbreakers, hydraulic shocks, patches of turbulence, and gravity-capillary waves  (both wind-driven and parasitic)—any or all of which could contribute to the scattered  clutter signal. For example, the common Stokes wave20  has a quasi-trochoidal structure that resem - bles a wedge on the surface, so wedge scatter might describe an important aspect of sea  clutter.11,12,92,93 The scattering model is usually some variant of the familiar geometrical  theory of diffraction  (GTD),109 which is strictly applicable to the backscatter problem  only when the edge of the wedge is normal to the plane of incidence. Nevertheless, the  cross section predictions at the lower grazing angles for both polarizations show trends  similar to the predictions of the Bragg or composite-surface models.93 One major problem with all models based on scattering feature simulations is the  lack of reliable information about the shapes, sizes, orientations, speeds, lifetimes  and statistics of the features themselves. 
 pp.425-433, Apr.1,1947. 46.Straiton, A.W.,andCW.Tolbert: Anomalies intheAbsorption ofRadioWavesbyAtmospheric Gases,Proc.IRE,vol.48,pp.898-903, May,1960. 47.Blake,L.V.:Prediction ofRadarRange,chap.2of"RadarHandbook," M.1.Skolnik (ed.),McGraw­ HillBookCompany, NewYork,1970. 
 A waveguide ceramic window is  necessary to maintain the vacuum in the tube and yet couple power out efficiently. Waveguide  arcing or thermal stresses are common causes of window failures. High-power tubes  sometimes employ an arc detector looking directly at the output window that allows either the  drive power to be removed or the beam to be shut o!T within a few tens of microseconds after  the presence of an.' arc is detected. 
 C., J. T. Ransone, Jr., and W. 
 Either we can arrange the H2S displayed map to be  always with its top (on the tube) representing the  direction of flight, or we might link the H2S display with  the gyro-compass of the aircraft, so that the map is  _always pointed to true north. For civil aviation over  considerable areas of land the latter system is to be  preferred if it is possible. Over land H2S-type sys-  tems show up towns, large buildings, and prominent  - coastline formations. 
 If it is assumed tliat this gradient is constant with  height and equal to a value of 39 x per meter, the value of k is 4. The use of the 4 effective  earth's radius to account for the refraction of radio waves predates radar and, because of its  convenience, has been widely used in radio communications, propagation work, and radar.13  It is only an approximation, however, and may not yield correct results if precise radar  measuremetits are desired, as, for example, in a long-range height finder. The term sttrr~dar.ci  refiactiorl is applied whet1 tlie index of refraction decreases uniformly with altitude in si~cll a  rnatirier that k = 4 (Ref. 
 SCALE PLASMA INSTABILITIES  MAY ENDURE FOR A FRACTION OF A SECOND  OTHERS FOR TENS OF SECONDS  EVIDENT TO RADARS AS SPREAD 
 WISE DIRECTION AT AN ALTITUDE OF  M AND A SPEED OF  MS IT IS APPROXIMATELY . 
 BASED VERSION CALLED &,9 
 /Ê*,", - 5SING THE POWER OF THE PERSONAL COMPUTER IN CONJUNCTION WITH THE MATURITY OF  %- SYSTEM AND ENVIRONMENTAL PROPAGATION MODELING  ASSESSMENT PROGRAMS AND ASSOCIATED SOFTWARE ALLOW A USER TO DEFINE AND MANIPULATE REFRACTIVITY AND OTHER NATURAL ENVIRONMENT DATA  RUN PROPAGATION MODELS ON THAT DATA  AND DISPLAY THE  RESULTS IN TERMS OF EXPECTED PERFORMANCE ON ACTUAL OR PROPOSED ELECTROMAGNETIC  SYSTEMS 7HILE THERE ARE SEVERAL ASSESSMENT SYSTEMS IN USE WITHIN THE 53 AND IN VARIOUS OTHER COUNTRIES  THE FOLLOWING DISCUSSION IS LIMITED TO !2%03 )T IS USED EXTENSIVELY THROUGHOUT THE 53 $EPARTMENT OF $EFENSE $O$  AND OTHER FEDERAL GOVERNMENT AGENCIES  53 PRIVATE INDUSTRY  THEIR FOREIGN COUNTERPARTS  AND BY PRIVATE INDIVIDUALS !2%03 GREW OUT OF AN URGENT MILITARY OPERATIONAL REQUIREMENT FOR RADAR PERFOR 
 512 INTRODUCTION TO RADAR SYSTEMS  atmospheric turbulence which is detectable by radar. "Ring echoes " have been observed on  PPI displays that start at a point and form a rapidly expanding ring.100 After one ring grows  to a diameter of several miles, a second -ring forms. Other rings can form similarly. 
 Mayer, Radar Target Detection: Handbook of Theory and Practice.   New York: Academic Press, 1973. 68. 
 VI would have been the same. The performance of ASV Mk. VIIwould have been worse, due to increased clutter returns despite the reduced azimuth beamwidth, due to increased clutter re ﬂectivity at X-band. 
 ERROR SIGNALS 4HE MODULATION  CAUSED BY THE MICROWAVE RESOLVER IS OF CONCERN IN INSTRUMENTATION RADAR APPLICATIONS BECAUSE IT ADDS SPECTRAL COMPONENTS IN THE SIGNAL  COMPLICATING THE POSSIBLE ADDITION OF PULSE DOPPLER TRACKING CAPABILITY TO THE RADAR 4HIS SYSTEM PROVIDES INSTANTANEOUS !'# OPERATION WITH ONLY TWO )& CHANNELS AND  OPERATION WITH REDUCED PERFORMANCE IN CASE OF FAILURE OF EITHER CHANNEL (OWEVER  THERE IS A LOSS OF  
 The amplitude modulation is a(t) = A rect ( t/T ) and the phase modulation is a  quadratic function of time:  f (t) = pa t2 (8.3) The frequency modulation, defined as the instantaneous frequency deviation from  the carrier frequency f0, is expressed in terms of the phase modulation by  f td dti( )=1 2πφ (8.4) The frequency modulation for an LFM waveform is linear with slope equal to a  f t t B T t t Ti( ) ( / ) ,| | / = = ± ≤ α 2 (8.5) ch08.indd   3 12/20/07   12:49:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 
 R .. G. D. 
 61. Kelley, J. H.: Minutes of Space Nuclear Power Service Working Group Meeting, Sept. 
 We predict the forward and backward pulse by exploiting the observed echo information. Detailed forward and backward prediction algorithm will be given in the Section 3.2. The echoed signal of one range cell in the slow time domain is shown in Figure 3. 
 The result is thesame whether theconcave orconvex side isturned toward theradar transmitter. IFormore detailed discussion seeVol. 13ofthisseries, (’hap. 
 TRACING CAN BE PERFORMED ON ANALYTIC PROFILES FITTED TO 24)- DATABASES 4HE MOST ACCURATE PREDICTIONS COME FROM THE APPLICATION OF SOPHISTICATED RAY 
 pp.14921~01.August. I95R. 24.Crane.R.K.:Ionospheric Scintillation. 
 VIA 3 Wellington squadrons;ASV Mk. VIB No. 179 Squadron Warwicks;ASV Mk. 
 Theyactin apassivemannertochangetheenergyreflected backtotheradar.Examples ofpassiveECM arechafr.decoys,andradarcross-section redllction. Oneoftheearliestformsofcountermeasures usedagainstradarwas cJl(~frChaffconsists ofalargenumberofdipolereflectors, usuallyintheformofmetallic foilstripspackaged asa bundle.Themanyfoilstripsconstituting thechaffbundle,onbeingreleased fn,Hllanaircraft, arescattered bythewindandblossom toformahighlyreflecting cloud.Arelat!vely small bundleofchaffcanformacloudwitharadarcrosssectioncomparable tothatofalarge aircrart. Chaffisusedeithertodeceiveortoconfuse. 
 FIED USING THE SAME MEASURES  OR BECAUSE THEY CAN BE SPECIFIED  EXACTLY  THEY ARE FRE 
 2 Since the signal-to-noise ratio is proportional to l/ R4 (from the  radar equation), the angular error due to receiver noise is proportional to the square of  the target distance.  Servo noise is the hunting action of the tracking servomechanism which results from  backlash and compliance in the gears, shafts, and structures of the mount. The magnitude of  servo noise is essentially independent of the target echo and will therefore be independent of  range. 
 NOISE AMPLI 
 SPEED TARGETS(IGHER SENSITIVITY TO DOPPLER SHIFT 4IME SIDELOBES INCREASE WHILE MAINLOBE RESPONSE DECREASES FOR HIGHER DOPPLER CHARACTERISTIC OF A THUMBTACK 
 R., Jr.: A Dual-Mode Latching Reciprocal Ferrite Phase Shifter, I £EE Tran\.,  vol. MTT-18, pp. 1119-1124, December, 1970. 
 Radar Conf., pp. 12-16, Washington, 1985. CHAPTER 18 TRACKING RADAR Dean D. 
 901-920, August, 196S.  30. Olin, L D., and F. 
 FEED SYSTEM DIVIDES POWER VERY SIMPLY IN ONE  STEP FROM THE FEED TO THE MANY ELEMENTS ON THE APERTURE )N CONTRAST  THE CONSTRAINED 
 In active array systems, the receiver input is derived from the receive beam - forming network. Active array antennas include low-noise amplifiers prior to forming  the receive beams; although these are generally considered to be antenna rather than  receiver components, they will be discussed in this chapter. FIGURE 6.1  General configuration of a radar receiverSTC  Attenuator IF LimiterAGC  Attenuator COHODirect  Digital  SynthesizerSingle  Receiver  Channel  replicated  N timesReceiver InputExciter Output I I Q Q Data to Digital Signal ProcessorI/Q  DemodulatorReference  Oscillator A/DA/DSTAL O Direct  Digital  ConversionA/DIF Limiter Clock  Generator A/D Clocks STC = Sensitivity Time Control  AGC = Automatic Gain Control STALO = Stable Local Oscillator COHO = Coherent Local Oscillator A/D = Analog-to-Digital ConverterBandpass  Filter Bandpass  FilterBandpass  Filter Bandpass  Filter A/D ClocksA/D  ClockSTC &  AGC Control ch06.indd   2 12/17/07   2:02:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
     
 Clutter  maps store an average background level for each range-azimuth cell. A target is then  declared in a range-azimuth cell if the new value exceeds the average background level  by a specified amount. Optimal Detector. 
 Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 12.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 Feed arrays, such as that illustrated in the ARSR-4 reflector antenna shown in  Figures 12.31 and 12.32, have also been used to enable shaped beams and low side- lobe patterns. Passive combiner networks are used to generate multiple receive beams  stacked in elevation and a single transmit beam. 
 2011 ,49, 3703–3712. [ CrossRef ] 18. Zeng, T.; Wang, R.; Li, F. 
            
 II on different aircraft were issued by the Radio Department at RAE (e.g. [ 10,11]). Installations were also tested by CCDU [ 12]. 
 9.10). Specific electronic techniques take place in the main radar subsystems, namely, the antenna, transmitter, re- ceiver, and signal processor. Suitable blending of these ECCM techniques can be implemented in the surveillance and tracking radars, as discussed in Sec. 
 As thus defined, Vn is the open-circuit voltage at the resistor terminals. If an external impedance-matched load of resistance RL = R is connected, the noise power delivered to it will be Pn = kTBn (2.30) . which does not depend on the value of R. 
 Inmany applications, however, the presence onthe radar screen ofstorm echoes (that is,echoes from rain drops within astorm area) isobjectionable for either oftwo reasons. (1)Asmall isolated storm cloud atlong range may bemistaken foralegitimate target; airborne sea-search radar is especially vulnerable tothis kind ofconfusion. (2)Echoes from astorm area may mask orconfuse theechoes from targets atthesame range and azimuth. 
 S., and J. S. Marshall: The Distribution with Size of Aggregate Snow- flakes, J. 
 K. Moore, Traveling Wave Engineering , New York: McGraw-Hill Book Company, 1960. 54. 
 Wolde and A. Pazmany, “NRC Dual-frequency airborne radar for atmospheric research,”  presented at 32cd Conf. Radar Meteorol. 
 Forthisreasonthey arealsocalledt/tin1ledarrays. Thedesignofathinnedarrayconsistsofselecting thediameter oftheaperture togivethe desiredbeamwidth, selecting thenumberofelements togivethedesiredgain(gainisdirectly proportional tothenumber ofelements), andarranging theelements toachievesomedesirable property ofthesidelobes, suchasminimizing thepeaksidelobeorapproximating somedesired radiation pattern. Therehavebeenmanymethods proposed intheliterature fordetermining theelement spacings (orlocations withintheaperture) ofsucharrays.Onlytwowillbe mentioned here:dynamic programming anddensitytapering.. 
 For the remaining filters, a relative spac - ing of D = 1/25 = 0.04 was used, but this could be reduced in order to minimize  doppler straddling losses. The third filter in the filter bank is shown in Figure 2.60.  FIGURE  2.58 Doppler filter design constraints120 90 30 0 60 150 180 210 240 270 300−100−80−60−40−200 4 296Radial Velocity – vr (m/s)Maximum Response – R (dB) FIGURE  2.59 Leftmost FIR filter in doppler filter bank design0.4 0.3 0.1 0 0.2 0.5 0.6 0.7 0.8 0.9 1−100−80−60−40−200 Relative Doppler – fdTMaximum Response – A (dB) Mismatch loss = 1.2869 dB ch02.indd   57 12/20/07   1:45:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 In Proceedings of the Advances in neural Information Processing Systems, Lake Tahoe, NV , USA, 5–8 December 2013; pp. 2553–2561. 22. 
 SION  -AGELLAN HAD RETURNED MORE DATA THAN ALL PRIOR PLANETARY MISSIONS COMBINED  4HE RADAR OPERATED IN THREE MODESIMAGER  ALTIMETER  AND RADIOMETERINTERLEAVED DURING EACH PASS  4HE 8 BAND DATA DOWNLINK SUPPORTED DATA RATES OF  KBITS OR   KBITS 4HE  
 TABLE 15.1 Summary of Standard Deviations of the Clutter Spectrum* *From Barton.2 wind velocity with altitude). Their measurements indicate that good average val- ues are av = 1.0 m/s for turbulence and crv = 1.68 m/(s/km) for wind shear. A convenient equation is av = 0.04/?6el m/s for the effects of wind shear, provided the rain fills the vertical beam, where R is the range to the weather, in nautical miles; and vel is the one-way half-power vertical beam width, in degrees. 
   2!$!2 $)')4!, 3)'.!, 02/#%33).'   Óx°£x REQUIRED TO REALIGN THE DATA IN THE TWO PATHS  AND THIS CAUSES THE ) AND 1 OUTPUT VALUES  TO BE EFFECTIVELY SAMPLED AT THE SAME INSTANTS 3IGNAL 
 TERM OPERA 
 O. Sokal, “Power amplifiers and transmitters for RF and microwave,” IEEE Trans. Microwave  Theor. 
 (11.18) is to be expected. 6 (degrees) FIG. 11.25 The amplitudes of the principal-plane sidelobes of the RCS of a flat rectangular plate are independent of frequency. 
 Griffiths, H. D., et al.: Television-Based Bistatic Radar, Proc. IEE, vol. 
 More important, since very slight mechanical changes will spoil a60-db balance between two equal voltages, such bridge systems tend tobehighly microphonics. The second modification relates totheintermediate frequency ofthe crystal mixer. The reader will have observed that the system iswell described asasuperheterodyne with zero intermediate frequency, the leakage from thetransmitter constituting the local oscillator power and the modulation frequency being the doppler frequency. 
 DIMENSIONALLY SAMPLED SPACE WHEN THE  DATA ARE DECOMPOSED INTO hSLOW TIMEv IN THE AZIMUTH DIRECTION  AND hFAST TIMEv IN THE RANGE DIRECTION  )N AZIMUTH  THE 02& CREATES ALIASED VERSIONS OF THE DATA ILLUMINATED BY THE MAIN BEAM OF  THE ANTENNA 4HE SPECTRA  OF THESE ALIASES ARE LOCATED AT MULTIPLES  OF THE 02& TO EITHER SIDE OF THE DOPPLER CENTROID OF THE MAIN BEAM /F COURSE  WHEN SAMPLED THEY ARE FOLDED BACK INTO THE .YQUIST PASSBAND 4HESE ALIASES ARE AZIMUTH AMBIGUITIES  WHICH ARE SUPPRESSEDHENCE NOT VISIBLEIN A WELL 
 The line normally operates with end cells down- ward sothat small remaining airbubbles will collect above the corner. SEC. 16.18] THE SUPERSONIC DELAY LINE 669 reflect orsout ofthe path ofthebeam. 
 TRACKING CIRCUITS OF A CONICAL 
 ING  THREATENING LOW 
 .1.) The angular region hetween the interference region and the quasi•specular region  is the plateau, or ditfi,se, region. The chief scatterers are those components of the sea that are  of a dimension comparable to the radar wavelength (Bragg scatter). Scattering in this region  i, similar to that from a rough surface. 
 The receiver noise is expressed relative to the thermal noise that would be produced by an ideal receiver. The thermal noise is equal to kTB, where k is Boltzmann's constant, T is the temperature, and B is the receiver bandwidth. The receiver noise is the thermal noise multiplied by the factor Fn, the receiver noise figure. 
 NENT OF THE VECTOR WIND FIELD (ENCE  EXACT MEASUREMENTS OF VECTOR WINDS AT A POINT ARE GENERALLY NOT POSSIBLE (OWEVER  ROTATING WINDS OR VORTICES CAN BE DETECTED AND . 
 A block diagram illustrating the principle of the FM-CW radar is shown in Fig. 3.1 1. A  portion of the transmitter signal acts as the reference signal required to produce the beat  frequency. 
 3.25 isanexample ofastructure which casts ashadow. Seen broadside from arelatively low angle, the wires and supports of the overhead electrification system and the embankment upon which the tracks arelaid intercept energy and cast their shadows inthe same k1:1IJ.3.26.—Increased nngle intercepted byinclined target area. Thelength inrange ofa PUISC packet, AR,is~cr. 
 About10to20scansarerequired toestablish steady-clutter v31ues.Asrainmoves in~othearea,oraspropagation conditions resultinchanging ground­ clutterlevels,thecluttermapchangesaccordingly. Thevaluesstoredinthemaparemultiplied byanappropriate constant toestablish thethreshold forzero-relative-velocity targets.This eliminates theusualMTIblindspeedatzeroradialvelocity andpermits thedetection of crossing ~argetsinclutterifthetargetcrosssectionissufficiently large. Thus,inFig.4.28thezero-velocity filter(No.1)threshold isdetermined bytheoutputof thecluttermap.Thethresholds forfilters3through 7areobtained fromthemeanlevelofthe signalsinthe16rangecellscentered aroundtherangecellofinterest. 
 This circum- stance isperhaps one reason why the effective receiving cross section ofanordinary radio antenna isanumber oflittle interest and isindeed rarely discussed inradio engineering texts. More significantly, it explains why the emphasis inthe development ofradio receivers has been mainly onimproving discrimination against some ofthe external noise (for example, bygreater frequency selectivity) rather than on reduction ofnoise inherent inthereceiver. The situation isdifferent inthe microwave region. 
 I  1234567 Figure 11.20 Seven-bit shift-register for generating a pseudo-  outplf random linear recursive sequence of length 127.  EXTRACTION OFINFORMATION ANDWAVEFORM DESIGN429 Table11.2Barkercodes Codelength 2 .\ 4 <; 7 II 1.1Codeclements +-.++ ++- 1-1--+.4++- 1 I I I! I I .1-- I!I! .I-I·-+-t·Sidelobelevel,dB -6.0 -9.5 -12.0 -14.0 -16.9 .-20.R -22,3 isillustraled schematically alappeddelaylinethat generates thisBarker-coded waveform whenanimpulse isincident attheleft-hand terminal. Thesametappeddelaylinecanbeused asthereceiver matched filteriftheinputisappliedattheright-hand terminal. 
 the threshold if noise alone were present, but would exceed it if a strong  signal were present. If the signal were small, however, it would be more difficult to recognize its  presence. The threshold level must. 
 155. Garver, R. V.: "Microwave Diode Control Devices," Artech House, (nc., 1976. 
 ENGINE AIRCRAFT. 
 J. H. Dunn and D. 
  
 The lobing of the  elevation pattern due to ground reflections results in wider elevation nulls at the lower  frequencies and can cause long fade times of the target signals. The elevation angle of the first  rnultipath lobe varies inversely with frequency (Sec. 12.2), so that low-altitude coverage is  more difficult to acliieve at tlie lower frequencies. 
 Suitable frequency agility can  accomplish the same result. Tradeoffs exist between spatial resolution and measurement precision. The latter  can be used to define a gray-level resolution .181 One can then think of image resolution  in terms of a volume:  V = raryrg  (16.33) ch16.indd   55 12/19/07   4:56:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 PENETRATION 3!2 3ECTION   4HE SYNTHETIC APERTURE TIME T ! REQUIRED TO COLLECT THE DATA FOR A SPOTLIGHT 3!2 IMAGE  IS FOUND AS FOLLOWS  DLL L LCR 3! SQ SQyy   y  $PP P2 ,2 6T T2! !COS   COS    6DCR SQCOS  P   WHERE 6 IS THE PLATFORM SPEED )NTERFEROMETRIC  3!2  )NTERFEROMETRIC 3!2 )N3!2  SOMETIMES ALSO CALLED  h)&3!2v  REFERS TO THE USE OF TWO ANTENNAS WHOSE SIGNALS ARE COMBINED COHERENTLY )N3!2 WAS ORIGINALLY DEVELOPED BY THE *ET 0ROPULSION ,ABORATORY *0,  TO DETECT OCEAN CURRENTS OR MOVING TARGETS   4HE TWO ANTENNAS WERE DISPLACED HORIZONTALLY  ON THE PLATFORM ALONG A LINE PARALLEL TO THE GROUND  SO THAT THE RECEIVED ECHOES FROM A MOVING TARGET WOULD BE DIFFERENT FROM THE CORRESPONDING ECHOES FROM FIXED TAR 
 Two versions were developed, one using a240-ft mast and theother a120-ft mast, thelatter being intended forrapid installation. Such tall structures were necessary inorder to obtain anarrow beamwidt hinelevation atthis low frequency. The antenna system ona240-ft mast consists ofnine groups, each ofeight horizontal dipoles, spaced vertically one above another. 
 In addi - tion, phase shifting for beam steering can be implemented at low power levels on the  input feed side of an active array module; this avoids the high-power losses of the  phase shifters at the radiating elements and raises overall efficiency. Also, peak RF  power levels at any point are relatively low because the outputs are combined only  in space. Furthermore, amplitude tapering can be accomplished by turning off or  attenuating individual active array amplifiers. 
 M.: A Low Noise CW Doppler Technique, Natl. Cot$ Proc. Aeronaut, Electronics  (Dayton. 
 ANGULAR FUNCTION  WHICH PRODUCES A  SINC   FUNCTION  SINX X   WITH A  
 Sheen, D.M.; McMarkin, D.L.; Hall, T.E. Three-dimensional millimeter-wave imaging for concealed weapon detection. IEEE T rans. 
 T B. i\.: Radio Propagation over a Discontinuity in the Earth's Electrical Properties. Proc. 
 Therefore the theoretical conversion loss can never be less than 3 dB with this  configuration. (The image frequency is defined as that frequency which is displaced from the  local oscillator frequency fi.0 by the IF frequency, and which appears on the opposite side of  the local oscilfator frequency as the signal frequency !RF. It is equal to 2JLo -faF .)  Short-circuiting or open-circuiting the image-frequency termination results in a" narrow­ band " mixer. 
 Amplitude Quantization . When the aperture of a phased array is divided into  equal subarrays, then the amplitude distribution across each subarray is constant.  Aperture taper for the antenna is approximated by changing the amplitude from subar - ray to subarray, and quantization lobes arise from these discontinuities. 
 Schwartz, E. J. Szoke, and S. 
 COlll'.Record. vol.4.pI.I,pr.39-47,1956. IJ.Page.R.M.:Monopulse Radar.IRENatl.ConI'.Record,vol.3.pt.8,pp.132-134, 1955. 
 directive elements whkh radiate.little or no energy in the directions of the undesired lobes. For  example, when the element spacing d = 2,1,, grating lobes occur at O :;;; ± 30° and ± 90" in  addition to the main beam at O = 0°. If the individual elements have a beamwidth somewhat  less than 60°, the grating lobes of the array factor will be suppressed. 
 Radartutorial (www.radartutorial.eu)   3    Figure 2: Cover of the patent script     Figure 1: “Würzburg Riese”, World War II radar  produced in 1940 by Telefunken (Germany)  Historical Overview   Neither a single nation nor a single person is able to  say, that he (or it) is the inventor of the radar  method. One must look at the “Radar ” than an  accumulation of many developments and  improvements earlier, which scientists of  several  nations parallel made share. There are nevertheless  some milestones with the discovery of important  basic knowledge and important inventions:       1865  The Scottish  physicist James Clerk Maxwell  developed his electro -magnetic  light theory (Description  of the electro -magnetic waves and her propagation)   1886  The German physicist Heinrich Rudolf Hertz  discovers the electro -magnetic  waves and prove s the theory of Maxwell with that. 
 RESOLUTION 3POT3!2 BETTER THAN  M   
 Maisel, L.: Performance of Sidelobe Blanking Systems, IEEE Trans., vol. AES-4, pp. 174-180, March 1968. 
 L.G,Levoy, Jr.,“Parallel Operation ofMain Engine-driven 400-cycle Aircraft Generator,” AIEE‘l%msactions, 64,811-816 (December 1945). W.K.130ice andL.G.Levoy, Jr.,“Aircraft Alternator Drives,” .41EE Tran-r- acticms, 64,534-540 (July 1945). M.M,Hubbard, “Investigation of>phase 208/120-volt 400-cycle Aircraft Alternators)” RLGroup Report 56-061545.. 
 Staprans, W. McCune, and J. A. 
 AOSP program technical goals include (1) prime power of 100 W, (2) weight of 100 Ib, (3) volume of 2 ft3, (4) 5-year life with a probability of survival of 95 percent, and (5) an input rate of 50 million words per second.32'56 Prime Power. The performance of any SBR will ultimately be limited by the prime power system. The most frequently utilized source of prime power for satellites is the solar-battery configuration. 
 PLER FILTER BANK TRAILING OR LEADING  THE DETECTION FILTER BANK BY ONE PULSE REPETITION INTERVAL 02)  IS SAVED 4HIS EXPLAINS WHY A #0) OF  N    PULSES IS NEEDED TO IMPLEMENT  THE 36# CONCEPT &OR EACH PRIMITIVE DETECTION IN A #0)  CALCULATE THE SET OF ALL POSSIBLE TARGET RANGES OUT TO THE MAXIMUM INSTRUMENTED RANGE 2 MAX  }}      M AX 2RM 2 M MII I    02) WHERE 02) M2 2 II MAX MAX  INT                  WHERE 202) I IS THE AMBIGUOUS RANGE INTERVAL CORRESPONDING TO THE  ITH #0) !FTER THE  PRIMITIVE DETECTIONS FROM ALL #0)S IN THE PROCESSING DWELL HAVE BEEN PROCESSED  THE VALUES OF }2 I FROM ALL #0)S ARE SORTED INTO A SINGLE LIST ! FINAL RANGE DETECTION AND  ITS TRUE RANGE IS THEN FOUND AS A CLUSTER OF THREE PRIMITIVE DETECTIONS HAVING POSSIBLE RANGES WITHIN AN ERROR WINDOW OF TWO TO THREE TIMES THE STANDARD DEVIATION OF THE AMBIGUOUS RANGE ESTIMATE 4RUE 2ADIAL 6ELOCITY $ETERMINATION  &OR EACH TRUE TARGET DETECTION  AN UNAM 
 B. Goldberg: Applications of the Turnstile Junction, I RE Trans., vol. MTT-3,  pp. 
 Early evidence of the effect of rain on sea clutter was mainly anecdotal; for  example, radar operators would report that sea clutter tends to decrease when it starts  to rain. However, there has been little in the way of reliable, quantitative experimental  information about the interaction between rain and wind-driven sea clutter in the open  ocean. Laboratory measurements by Moore et al.67 with artificial “rain” suggested that  for light winds the backscatter level increased with the rain rate, while for heavy winds  rain made little difference. 
 2.6 Required signal-to-noise ratio (detectability factor) as a function of number of pulses noncoherently integrated, square-law detector, Swerling Case 1 fluctuating target, and 0.5 probability of detection. (From Ref. 13.) The distribution of Eq. 
 The coaxial  magnetron, however, with stabilization controlled by the outer cavity, permits stable  operation with a larger number of cavities, and thus with greater power. The anode  and cathode structures of a coaxial magnetron can also be bigger, which further allows  operation at higher power. The larger structures permit more conservative design, with  the result that it has longer life and better reliability than conventional magnetrons,  as well as more stable operation. 
 FEED NETWORK 3UM 
 Curve A represents the frequency-time history of the transmit- ter (and local oscillator) and curves B and C that of returns from two different ranges. Note that the vertical distance between curves (e.g., curves D and E) yields a heuristic picture of the average frequency behavior of the difference signal from the mixer. This is somewhat naive. 
 NALS )T SHOULD BE NOTED THAT FOR AMPLIFIERS  COMPRESSION POINT AND THIRD ORDER INTERCEPT ARE USUALLY SPECIFIED AT THEIR OUTPUT WHEREAS FOR MIXERS THESE PARAMETERS ARE USUALLY SPECIFIED AT THEIR INPUT !DDITIONAL SPECIFICATIONS FOR MIXERS INCLUDE ,/ DRIVE POWER  PORT 
 R. Cooke: Unsupervised Tracking of Maneuvering Vehicles, IEEE Trans.,  ml. AES-9. 
 46. Linde, G. J.: Improved Low-Elevation-Angle Tracking with Use of Frequency Agility, Nauul Research  Laboratory ~e~t. 
 VAPOR RADIOMETER 762  AT  AND  '(Z  DATA FROM WHICH ARE USED TO REDUCE THE CORRESPONDING PROPAGATION UNCERTAINTY TO  CM  o  &ULL DERAMP OR SIMPLY DERAMP  IS STANDARD TERMINOLOGY IN SPACE 
 PULSE INTERFERENCE IS PRESENT  THE INDIVIDUAL POWER RATIOS CAN BE SOFT 
 LEAVED WITH THE HIGHEST PERFORMANCE VELOCITY 
 24, pp. 25–114, October 1981. 14. 
 If  one assumes that the clutter signal is wavelength independent and the antenna beam - width is fixed, it can be shown that the weather-signal-power to clutter-power ratio is  inversely proportional to l2. Weather radars typically use digital signal processing techniques to implement  clutter filters that suppress near zero velocity clutter echoes.59 These filters may be  implemented using either a time domain clutter filter applied to the I and Q radar  video data (one form of which is sometimes called a delay line canceler  from its early  analog implementation) to suppress the zero velocity ground clutter components or a  frequency domain doppler power spectrum (a digital “filter bank”) to achieve the same  effect.32 The time domain filters for mechanically scanned weather radars are usually  infinite impulse response (IIR) filters with narrow, but adjustable, widths up to a few  m/s and having suppression levels of 40–60 dB and very steep transition regions.60  These time domain filters with a frequency notch centered at zero velocity (frequency)  ch19.indd   13 12/20/07   5:38:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 the larger the number of pulses integrated, the more likely it will  be for the fluctuations to average out. and cases 2 and 4 will approach the nonfluctuating case.  Curves exist ii .. 
 4(% 
 That is, the half-power beamwidth is given by . HPBW = K/(D/\) = KX/D (6.11) where D is the aperture dimension, X is the free-space wavelength, and K is a proportionality constant known as the beamwidth factor. Each amplitude distri- bution (assuming a linear phase distribution) has a corresponding beamwidth fac- tor, expressed either in radians or in degrees. 
                                    
  WITHOUT A TAILFIN !SIDE FROM THIS  IT IS INTERESTING THAT THE & 
 If (and  only if) the LOS remains perpendicular to the direction of flight, range resolution is  sometimes called cross-track resolution , and crossrange resolution is sometimes called  along-track resolution . With respect to SAR resolution, the preferred terms are fine and coarse . Better  resolution is finer , not greater ; poorer resolution is coarser , not less. 
 Care must be taken, however—if the array or reflector function is used without con - sidering the weighting of the elemental pattern or the feed distribution, the inherent  sidelobe pattern can obscure the main-beam compensation results. Again, the performance versus doppler frequency is important for evaluating  overall radar detection performance. Antenna sidelobe limited performance can be  approximated by performing the lower integral of Eq. 
 PULL CIRCUIT DESIGN "Y USING A PUSH 
 Sidelobe Clutter. As with a monostatic radar, a bistatic radar must contend with sidelobe clutter. When both transmitter and receiver are ground-based and separated by a baseline range L, only ground clutter from regions having an adequate line of sight (LOS) to both the transmitter and the receiver will enter the receiver antenna sidelobes. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 5.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 of the scatterer above the center of gravity. 
 X. Sciamhi. A. 
 The gain of a  typical cosecant-squared antenna used for ground-based search radar might be about 2 dB  less than if a fan beam were generated by the same aperture.  The maximum gain of an antenna is related to its physical area A (aperture) by  G _ 41tAp  -.A.2 (2.49)  where p = antenna efficiency and A= wavelength of radiated energy. The antenna efficiency  depends on the aperture illumination and the efficiency of the antenna feed. 
 For the 58-cm depth shown, much of the scatter at 1.6 and 2.5 GHz is probably from  the underlying surface. Some reports state that there are radar hot  spots in snow cover, particularly at  35 GHz. These reports result from improper interpretation of variations that are due  to normal Rayleigh fading of the signal. 
 1, New York: Wiley, 1999 (updated 13 July 2007), pp. 263–289. 94. 
 6.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 The primary function of RF filtering is the rejection of the image response due to  the first downconversion. Image rejection filtering can be alleviated using an image  reject mixer; however, the maximum rejection achievable by image reject mixers is  typically inadequate without the use of additional rejection through filtering. This  image-suppression problem is the reason why some receivers do not translate from the  received signal frequency directly to the final intermediate frequency in a single step. 
 [ CrossRef ] 41. Bai, L.; Jiang, L.M.; Wang, H.S.; Sun, Q.S. Spatiotemporal characterization of land subsidence and uplift (2009–2010) over wuhan in central China revealed by terrasar-x insar analysis. 
 TERS 4HE AVAILABILITY  RESOLUTION  AND ACCURACY OF THESE MEASUREMENTS MUST ALL BE TAKEN INTO ACCOUNT WHEN DESIGNING THE DEINTERLEAVING SYSTEM BECAUSE THE APPROACH USED DEPENDS ON THE PARAMETER DATA SET AVAILABLE /BVIOUSLY  THE BETTER THE RESOLUTION AND ACCURACY OF ANY PARAMETER MEASUREMENT  THE MORE EFFICIENTLY THE PULSE 
 The EBS is claimed to  be broadband and to have high gain (25 to 35 dB), high efficiency (50 percent), and long life. At  1 GHz, an EBS amplifier might be capable of a peak power of 2 to 3 kW, and an average  power of about 200 W. The EBS has decreasing capability at the higher frequencies. 
 GET IMAGE 4HE GROUND REFLECTIVITY HAS BEEN ASSUMED EQUAL TO THE TARGET REFLECTIVITY THIS IS QUITE A PESSIMISTIC ASSUMPTION  BECAUSE IN MANY CASES OF PRACTICAL INTEREST  THE TARGET REFLECTIVITY IS HIGHER  ! RECEIVER THERMAL NOISE   D" BELOW THE TARGET RETURN  HAS ALSO BEEN SUMMED TO THE RECEIVED SIGNAL 4HE GROUND ECHO IS FIRST CAN 
 For this reason, the statistical implications of experimental data can be properly compared only if the details of the sampling procedure are specified. However, the number of samples in the experimental results shown thus far have been suf- PERCENT EXCEEDED WIND SPEED: LOWMEDIUMHIGH SEA SPIKES . ficiently large that the differences between, for example, Figs. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 7 .10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 summed and compared with a second threshold M. 
 QUENCY INTERFERENCE v  0ROC )%%%  )NT 2ADAR #ONF   !RLINGTON 6!   53!  -AY n     PP n  , "6AN "RUNT  h0ULSE 
 Atargetisdeclared tobepresentonlyifthreshold crossings areobserved fromthesamerangecellonbothtransmissions. Thesecondtransmission mightalsobeof greaterresolution aswellashigherpower.Whenthetwothresholds areoptimized, ithasbeen foundthatasecondtransmission isemployed inaboutfourpercentofthebeampositions:oIt isclaimed thatapowersavingoffrom3to4dBcanbeobtained ascompared withuniform scanning.42 j to.5DETECTOR CHARACTERISTICS Theportionoftheradarreceiver whichextracts themodulation fromthecarrieriscalledthe detector. Theuseofthistermimpliessomewhat morethansimplyarectifying element. 
  +A n  (IGH 4#$, 8  
 Figure 8.17 (AN/SPS-48) shows a stack of slotted waveguides  for forming a beam that is frequency-scanned in elevation. The slotted guides forming the rows  of the antenna are sometimes called sticks. The power coupled out of the guide by the slot is a  function of the angle at which the slot is cut. 
   . 
 A. Houze Jr., S. S. 
 Rec .,  Arlington, V A, April 21–23, 1975, pp. 385–390. 42. 
 PATH TRANSMIT SIG NAL AS A REFERENCE IN  A CORRELATION RECEIVER  WHICH CROSS 
 If a pulse  doppler dwell is required to update the track in clutter, the waveform should be selected to  place the target near the center of the ambiguous range-doppler detection space. Finally,  the track can be updated with the ambiguous range-doppler detection because the track  state-vector can be used to remove the ambiguity. 7.4 NETWORKED RADARS Ideally, a single radar can reliably detect and track all targets of interest. 
 LOSS DESCRIPTORS SUCH AS THOSE SHOWN IN &IGURE  &OR EXAMPLE  CONSIDER A RADAR AT  -(Z WITH AN AVERAGE POWER OF  K7  D"7   A TRANSMIT 
 13.Neuf,D.:RadarRetrofit: Increase Receiver Sensitivity CostEffectively, Microwave SystemNews,vol. 5,pp.55-60,April/May, 1976. 14.Anand,Y.,andCHowell: ABurnout Criterion forSchottky-Barrier MixerDiodes,Proc.IEEE,vol. 
 As P increases, the peak-sidelobe-voltage ratio approaches (irP)"1. This corresponds to approximately a 10 dB improvement over pseudorandom sequences of similar length. The ambiguity response over the range-doppler plane grossly resembles the ridgelike characteristics associated with linear-FM waveforms, as contrasted with the thumbtack characteristic of pseudorandom sequences. 
 Burk, G. J., and A. J. 
 Military 3D radars can be found at L band, but they also are at S band. L band is also suitable for large radars that must detect extra- terrestrial targets at long range. S Band (2.0 to 4.0 GHz). 
 This enables adjustment ofthe depression angle ofthe radar beam tothe optimal value forany altitude. Atiltmeter calibrated inaltitude isprovided; itserves asanapproximate guide tothecorrect setting. 4.Asearch-beacon switch. 
 This subject is treated in Chapter 6 of Willis and Griffiths.2 ch23.indd   18 12/20/07   2:21:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 
      
 16.19 for a range of normalized plat- form motion Vn as a function of normalized scanning displacements Wn. The V TNORMALIZED PLATFORM MOTION Vn = , x pa FIG. 16.19 DPCA improvement factor versus normalized platform motion Vn as a function of normalized scanning motion Wn. 
 May,1959_ 50.Glegg.K.C.M.:ALowNoiseCWDoppler Technique, Natf.ConfProc.Aeronaut, Electronics (Dayton. Ohio).pro133-144. 1958. 
 J. Phys., vol. 45, pp. 
 This link in the chain  was, to a certain degree, wishful thinking in the year  1926, as there was then no known way of modulating  the light with the requisite degree of speed and precision.  But the patent boldly stated that a spot of light projected  from this source would “‘traverse a screen in synchron-  ism with the exploration of the object.” Although it is  very doubtful if such a system could be made to work  (the ‘scanning’ was to be done on the receiving side,  and not by the exploration of the object with the trans>  mitted radio-wave beam, as in modern H2S), this  British patent is nevertheless a step in radar develop-  ment.  French technicians were also early in the field of  radar,.and in 1933 were working on a system of ‘obstacle  detectors,’ using what was at that time thought to be  the fantastically short wavelength of 10 centimetres. 
 Staprans et al.18   © IEEE 1973 )Interaction structureP P IN Gun Interaction Impedance Distance (a)Out Collector Z0 Impedance (b) (c)Impedance Input Output load Impedance (d) ch10.indd   12 12/17/07   2:19:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. The Radar Transmitter. 
 D. B. Chelton, E. 
 Saunders, W. K.: Control of Surface Currents by the Use of Channels, I RE Trans., vol. A P-4,  pp. 
 The width of the spectrum due to vehicle motion determines the ability of the radar to detect this target motion. 12.5 MEASUREMENT TECHNIQUES FOR GROUND RETURN Special-purpose instrumentation radars and modified standard radars may be used to determine the ground return. Since the ground return is almost invariably due to scattering, these systems are termed scatterometers. 
 Some military systems such as the Patriot with the ±60° cone  of instantaneous view is fixed on its vehicle without a pedestal and is dependent on  movement of its vehicle to change the region of angular coverage as needed. The  advantages of space fed arrays are ● Conventional monopulse microwave horn feeds are used. ● Array elements are available with selectable polarization of the radiated energy when  fed by an optimized linear polarized monopulse feed (such as in Figure 9.7) and select - able receive-polarization as well. 
 WAY TRANSMISSION PATH 4O ACCOMPLISH THIS DISPLACEMENT  NEAR 
 Thus centimetric radar sets working up to I0  centimetres can have wave-guides which are, in fact, not  much bigger than household drain-pipes, and the energy  is literally ‘piped’ from T to aerial and from aerial to R. °  . CENTIMETRIC TECHNIQUE Irs  Electrical losses in these wave~guides are very small, and  their efficiency at such high frequencies is much better  than could be achieved with normal aerial transmission  lines. 
 W. HANSEN 6.1. General Considerations. 
 D. E. Barrick, “Remote sensing of sea state by radar,” Chapter 12 in Remote Sensing of the  Troposphere , V .E. 
 The most probable launch vehicle for the SBR is the STS (shuttle). Therefore, STS capabilities to put various payloads that include one or more SBR satellites (and the propulsion systems to place them into the desired orbits) must be considered. Figure 22.8 shows the STS cargo weight as a function of orbit inclination angle for various circular orbital altitudes and orbital-ORBlTALTlTUDE (nm)5-YEAR TOTAL-DOSE RAD(SI) . 
 Thepresence ofthesubreflector infrontofthemainreflector intheCassegrain configuration causesaperture blocking. Partoftheenergyisremoved, resulting inareduction ofthemain-beam gainandanincrease inthesidelobes.Ifthemainreflector iscircular and assumed tohaveacompletely taperedparabolic illumination, asmallcircular obstacle inthe centeroftheaperture willreducethe(power) gainbyapproximately [1-2(DbID)2]2,where D"isthediameter oftheobstacle (hyperbolic subreflector) andDisthediameter ofthemain aperture.19Therelative (voltage) levelofthefirstsidelobe isincreased by(2D"ID)2. For example ifD"ID=0.122,thegainwouldbelowered byabout0.3dBanda-20dBsidelobe wouldheincreased toabout-18dB. 
 at  some convenient height, the air temp·erature, relative humidity, and wind speed.18 These four  measurements have been found sufficient for the description of ducting conditions.  The above has been concerned with ,propagation beyond the normal horizon. Within the  horizon, the refractive· effects of the 'duct can lead to a modification of the normal lobing  pattern caused by the interference of the'.direct ray and the surface-reflected ray. 
 § ©¨ ¨¨ ¨ ¨¶ ¸· ·· · ·    &)'52%     (ISTOGRAM OF PEAK TIME SIDELOBE LEVELS FOR  
 CEDURE AND EFFICIENT IMPLEMENTATION OF THE FAST &OURIER TRANSFORM &&4  ALGORITHM IS PARTICULARLY ATTRACTIVE 4HROUGH THE USE OF APPROPRIATE WEIGHTING FUNCTIONS OF THE TIME 
 35, pp. 1010–1018, 1999. 82. 
 For general MTI use, thelimiting type ofreceiver istobepreferred. However, there isatype ofMTI system inwhich moving targets are detected inthe clutter bythe fluctuations which they produce inthe clutter amplitude. The lin-log receiver must beused insuch asystem, since thelimiting receiver cannot detect amplitude changes. 
 TIONAL RADAR COMPUTING IS SO ROBUST THAT 02& SETS CAN BE SELECTED IN REAL TIME BASED ON SITUATION GEOMETRY AND LOOK ANGLE 4HE SET  WHICH GENERATED &IGURE   ON THE AVERAGE IS CLEAR ON  OUT OF  02&S FOR A SINGLE TARGET %XCEPT FOR TWO SMALL DOPPLER REGIONS  ALL THE 02&S ARE CLEAR AT MAXIMUM  RANGE  WHICH PROVIDES MAXIMUM DETEC 
 P. Reilly, “Radar precipitation echoes—Experiments on temporal, spatial,  and frequency correlation,” The Johns Hopkins University, Applied Technology Laboratory,  Report No. Tech. 
 / Ê " 
 P. Swerling, “Maximum angular accuracy of a pulsed search radar,” Proc. IRE , vol. 
   30!#% 
     !         
 In Proceedings of the IEEE International Geoscience and Remote Sensing Symposium, Munich, Germany, 22–27 July 2012; pp. 5530–5533. 5. 
 (Afier BIore," IEEE Trans.) '  TilERADAR EQUATION 35 OJu 908070--- Measured - ---Calculated 30405060 Angular orientation 820\•I I I!., I / I / I I I /..,,/ 7-II I, 2-I I I-.r;c;, ~16­ Qj >o ~ ~11.5-o ::J 0" '"o l1J>o.0o o l1J Lo o.cu W Figure2.10Backscatter crosssectionofalongthinrod.(From!;eters,26 IRETrails.) downthelengthoftheobjectandreflectfromthediscontinuity atthefarend.Thisgivesriseto atraveling wavecomponent thatisnotpredicted byphysical opticstheory.26.3s ;\ninteresting radarscattering objectisthecone-sphere, aconewhosebaseiscappedwith aspheresuchthatthefirstderivatives oftheconeandspherecontours areequalatthejoin betweenthetwo.Figure2.11isaplotofthenose-onradarcrosssection.Figure2.12isaplotas afunction ofaspect.Thecrosssectionofthecone-sphere fromthevicinityofthenose-on direction isquitelow.Scattering fromanyobjectoccursfromdiscontinuities. Thediscontinui­ ties.andhencethebackscattering, ofthecone-sphere arefromthetipandfromthejoin hetween theconeandthesphere.Thereisalsoabackscattering contribution fcoma"creeping o br;!<-10·­ ~ 0­o o ~rv co-20f--f---------t------------::-­ (J=0.01>,,2 III '"1 ~-.30~e u (:; Uorr04 08 1.2 Diameter (Wavelengths) Figure2.11Radarcrosssectionofaconespherewith15°halfangleasafunction ofthediameter in wavelengths. (AfterBlore.27IEEETrailS.). 
 T arget LocationAspect Entropy without DenoisingAspect Entropy after Denoising Chevy Malibu (9.97, −5.22) 0.9469 0.5733 Ford Taurus Wag (12.43, −18.21) 0.9468 0.5567 Toyota Camry (20.66, −18.71) 0.9627 0.6118 Nissan Sentra (31.42, −28.87) 0.9460 0.5753 Hyundai SantaFe (22.68, −28.30) 0.9579 0.6024 Chevy Prizm (35.44, −41.72) 0.9536 0.5639 Trihedral 1 ( −24.39, 32.96) 0.8916 0.7918 Trihedral 2 ( −32.50, 33.41) 0.8887 0.7895 Trihedral 3 ( −32.14, 42.54) 0.8883 0.7915 Trihedral 4 ( −28.09, 38.67) 0.8868 0.7878 Trihedral 5 ( −13.86, 37.70) 0.8885 0.7918 Trihedral 6 ( −5.12, 22.98) 0.9001 0.7907 Dihedral 1 ( −15.55, 42.96) 0.8583 0.6805 Dihedral 2 ( −18.58, 33.53) 0.8587 0.7019 Dihedral 3 ( −26.15, 17.50) 0.8735 0.6841 Top-hat ( −17.00, 21.00) 0.9927 0.9927 (a)   (b)  Figure 15. Visual result of discrimination. ( a) Without denoising. 
 Effects of Motion Errors. In generating synthetic aperture antenna images, one needs to estimate the along-track and cross-track velocities of targets in order to derive the matched filter to use in imaging. If one has an error in the radial velocity of the target, one gets a rotation in target position. 
 If, on the other hand,fr < fd,  silcti as might occur with a high-speed target at short range, the roles of the averaging and the  difference-frequency measurements are reversed; the averaging meter will measure doppler  velocity, and the difference meter, range. If it is not known that the roles of the meters are 1  Indico tor Mixer -t Amplifier  ,- fionsmif fed s/gno/ Frequency  counter  Received signal  w 3 u  V C aI 3 H .+  C-  + 0 w Figure 3.12 Frequency-time relation-  ships in FM-CW radar when the  fr + fd received signal is shifted in frequency 0 by the doppler effect (a) Transmitted  m (solid curve) and echo (dashed curve)  (b) frequencies; (b) beat frequency.  CWANDFREQUENCY-MODULATED RADAR83 1ransmitfing antenna FM transmitterModulator Receiving. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 7 .6 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 where ∆q is the angular rotation between transmitted pulses. 
 RPVs can assist strike aircraft or missiles in penetrating radar-defended areas by jamming, ejecting chaff, dropping expendable jammers or decoys, acting as decoys themselves, and performing other related ECM tasks. According to the platform, the jammer can be classified as space-borne, air- borne, missile-borne, based on the ground, or based on the sea surface. A special class of missile-borne threat is the antiradiation missile (ARM), hav- ing the objective of homing on and destroying the victim radar. 
 X +E,HSIN   T A N QSQ 
 1326), thus connecting point Ttightly topoint Ssothat thecondenser ischarged totheinstan- taneous potential ofS. The leakage path from Ttoground ismade to have ahigh resistance sothat thepotential atTremains essentially con- stant until the new cycle, atwhich time itwill take anew value corre- sponding tothenew value ofthetime delay ofthesine pulse. Thus the potential atTwill gothrough thesame variations asthetime delay and will inthepresent case have theform A+Bsinoasdesired. 
 Anexample ofthedatastabilization isthecorrection appliedforyaw.IfaPPIwereto displayrelativebearing(azimuth) theapparent bearingwouldchangeastheplatform yawed. Withtheaidofahorizontal gyroscope toprovideanorthreference. acorrection signalcanbe ohtained whichcanbeappliedtotheindicator topermitthedisplayofthetargetinitstrue bearing ratherthanthebearing relative totheplatform heading. 
 266. Sensors 2019 ,19, 2605 The formulation that allows a linear transformation between the pixel brightness values is less restrictive, and can be written as: I(r+δr,t+δt)= M(r,t)I(r,t)+ C(r,t). (4) After using the Taylor series, the revised constraint equation can be obtained: It+Ir·rt−Im t−ct=0, (5) where mt=lim δt→0δm δtand ct=lim δt→0δc δt. 
 ,.! Figure12.13gives.theantenna, noisetemperature computed foratypicallO·ft-diameter parabolic reflector operating at1000MH2:asafunction oftheantenna elevation angle.61These dataassume(1)verticalpolarization, (2)theantenna locatedonaseacoast andlookingover. -10 9 +10 + 20  Antenna elevation angle, deg Figure 12.13 Computed antenna noise-temperature as a  function of elevation angle for a 10-ft-diameter (3 m)  parabolic-reflector antenna operating at a frequency of  1 GHz. (Afrer ~reene,~' courtesy Airborne Insrr~rtnen~s  Laboratory.)  the sea, (3) the antenna always pointing at the galactic center (4) no intense radio stars in the  antenna pattern, (5) resistive losses in the reflector, feed, and transmission line absorbing 2  percent of the incident power, and (6) the feed producing a parabolic illumination taper. 
 The air  in contact with the ocean’s surface is saturated with water vapor. A few meters above  the surface the air is not usually saturated, so there is a decrease of water vapor pres - sure from the surface to some value well above the surface. The rapid decrease of  water vapor initially causes the modified refractivity, M, to decrease with height, but  at greater heights the water vapor distribution will cause M to reach a minimum and,  thereafter, increase with height. 
 Dynamic range is 70 dB; minimum detectable  volumetric return is –26 dBZ. The PR mass is 230 kg; input power required is 270 W.  Peak power transmitted is 1.7 kW. 
 !XIS 4RACKING  4HE BEST RADAR TRACKING PERFORMANCE IS USUALLY ACCOMPLISHED  WHEN THE TARGET IS ESSENTIALLY ON THE RADAR ANTENNA AXIS 4HEREFORE  FOR MAXIMUM PRECISION TRACKING  IT IS DESIRABLE TO MINIMIZE LAG AND OTHER ERROR SOURCES AFFECTING THE BEAM POINTING ! TECHNIQUE CALLED  ON 
 Acker, A.: Selecting Tubes for Airborne Radars, Microwuc~e Sysrrrr~ News, vol. 7, pp. 55-60, May,  1977. 
 FREE REGION USUALLY DOES NOT EXIST WITH MEDIUM 02&S DUE TO DOPPLER FOLDING  4HE SIDELOBE CLUTTER REGION   6 2K IN WIDTH  CONTAINS GROUND  CLUTTER POWER FROM THE SIDELOBES OF THE ANTENNA  ALTHOUGH THIS CLUTTER POWER MAY BE BELOW THE NOISE LEVEL IN PART OF THE REGION 4HE MAIN 
 The  B-26 pattern in Figure 14.11 was measured at a frequency of 3 GHz. The polar format  is useful for display purposes but is not as convenient for detailed comparisons as is  a rectangular format like the one used in Figure 14.12. That rectangular pattern is of  a one-third scale model C-29 aircraft and was displayed in the early 2000s on a U.S. 
 Finally, the requirement of providing a high degree of clutter suppression at zero  doppler (land clutter) sometimes introduces special design constraints. When the number of pulses in a CPI is large ( ≥ 16), the systematic design pro - cedure and efficient implementation of the fast Fourier transform (FFT) algorithm  is particularly attractive. Through the use of appropriate weighting functions of the  time-domain returns in a single CPI, the resulting frequency sidelobes can be readily  controlled. 
 TENED DUE TO THE SLOWER SPEED OF IN SITU PROPAGATION !,3% 4HE !POLLO ,UNAR 3OUNDER %XPERIMENT   WAS A COMBINATION IMAGER  AND SOUNDER  OPERATING AT WAVELENGTHS OF  M   M  AND  M 4HE !,3% SOUNDER  &)'52%   4WO PROBLEMS THAT CHALLENGE SPACE 
 10. P. Mahapatra, Aviation Weather Surveillance Systems: Advanced Radar and Surface Sensors  for Flight Safety and Air Traffic Management,  London, UK: The Institution of Electrical  Engineers, 1999. 
 R.M.:Electronic Scanning: PastandFuture,Electronic Scanning Symposium. Apr.29-30. MayI.1958.AFCRC-TR-58-145(1). 
 SEC.8A] RADAR INTERROGATION VS. SPECIAL INTERROGATORS 253 systems beconceived asbroadly asthepossibilities forunified planning, control, and operation will permit. Let usfirst consider the planning ofbeacons foruse with airborne radar, which has been the subject ofsome controversy inthe past. 
 H. Knittel (eds.), Artech House, Inc., Dedham, Mass., 1972, pp. 240-242. 
 This collection of wave trains is described by a  two-dimensional spectrum (wave amplitude as a function of water-wavelength and direction or  travel). At grazing incidence the radar responds chiefly to the two wave trains which are  traveling toward and aw;1v from the radar, each with a water-wavelength Aw equal to half the  radar-wavelength Ar. For a grazing angle</>, this condition becomes Aw= (J..r/2) cos <f,. 
 FERENT PHASES OF CONVECTIVE AND TROPICAL RAINFALL AND ARE AVERAGED OVER SPACE OR TIME (OWEVER  THE hGAMMAv DROP 
 ING TO THE AVERAGE INTERPULSE PERIOD 4HE VELOCITY RESPONSE CURVE IS SYMMETRICAL ABOUT  ONE 
 Calculations for the element-steering phases are greatly simplified by the adop - tion of the direction cosine coordinate system. In this system, the linear-phase tapers  defined by the beam-steering direction (cos axs, cos ays) may be summed at each ele - ment so that the phasing at the mnth element is given by  ψmn xs ys = +mT nT   where Txs = (2p/l)dx cos axs = element-to-element phase shift in the x direction  Tys = (2p/l)dy cos ays = element-to-element phase shift in the y direction The array factor of a two-dimensional array may be calculated by summing the  vector contribution of each element in the array at each point in space. For an array  scanned to a direction given by the direction cosines cos axs and cos ays, the array fac - tor of an M × N rectangular array of radiators may be written  E A ea mM nN j mT(cos , cos ) | |[ (α αxs ys mn = =− =− ∑ ∑ 01 01 x x y T n T T − + −xs ys ) ( )]  where Tx = (2p/l) dx cos ax  Ty = (2p/l) dy cos ay  Amn = amplitude of mnth element An array may be visualized as having an infinite number of grating lobes only one  of which (namely, the main beam) is desired in real space. 
 Using fully polarimetric  data from a 33-GHz SAR, they showed that dihedral reflectors look quite different  from trihedral reflectors in fully-polarimetric SAR imagery. Few dihedrals exist in  Ka-band natural clutter; thus, if a portion of a SAR image corresponds closely to a  dihedral, then the region is likely to contain cultural (human-made) object(s).37 ch17.indd   22 12/17/07   6:49:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 2.55 Miscellaneous Losse s  ........................................  2.56  2.8 Jamming and Clu tter  ..............................................  2.56  Jamming  ............................................................ 
 In 1988, Dr. Sullivan had the privilege of working with Dr. Cutrona at the Environmental Research  Institute of Michigan, Ann Arbor (now General Dynamics, Ypsilanti), and is grateful for having learned much from  him concerning SAR. 
    ,AWRENCE 5NIVERSITY OF +ANSAS  2EMOTE 3ENSING ,AB    ' 0 DE ,OOR  0 (OOGEBOOM  AND % 0 7 !TTEMA  h4HE $UTCH 2/6% PROGRAM v  )%%% 4RANS   VOL '% 
 C  0  0 :,  C  !!  <l 0.1 "" '-0.90 X 0.40  "-.. 1.122 X 0.497  "-._1.372 X 0.622  ~ 1.872 X 0.872  ~""2.84 X 1.34  "" 3.4 X 1.7 .~  4.3 X 2.15 &  ~ ~ J>~  ~ 6.5x3.25 §  i;Oo'f. \. 
 STATE COMPONENT AND TRANSMITTER DESIGN WILL BE PRESENTED ££°ÓÊ  6 / 
 R. Ward and W. W. 
 TUDE AND RETAIN CONSTANT TRACKING LOOP GAIN ! TYPICAL !'# TECHNIQUE IS ILLUSTRATED IN &IGURE  FOR A ONE 
 Its purpose  is to preserve the short duration of the narrow impulsive spikes. These spikes are then clipped  by the limiter to remove a considerable portion of their energy. If the large noise spikes arc not  limited and arc allowed to pass they would shock-excite the narrowband IF amplifier and  produce an output pulse much wider in duration than the input pulse. 
 It was the magnetron thatmademicrowaveradarareality.Itwasthistechnologicaladvancethatmarksthe beginning of modern radar. Following the war, progress in radar technology slowed as post war prioritiesweredirectedelsewhere.Inthe1950snewandbetterradarsystemsbegan to emerge and the beneﬁts to the civil mariner became moreimportant. Although radar technology has been advanced primarily by themilitary, the beneﬁts have spilled over into many important civilianapplications,ofwhichaprincipalexampleisthesafetyofmarinenavigation.The same fundamental principles discovered nearly a century ago and thebasic data they provide, namely target range and bearing, still apply totoday’s modern marine radar units.. 
 The days when the radar screen was only viewable  in daylight on dim long-persistence monochrome CRTs through the aperture of a hood  are long gone. More recently, high brightness color CRTs are being replaced by Liquid  Crystal Display flat panel technology, which is helping to make the display more  user accessible—large stand-alone radar consoles are no longer necessary, allowing  improvements to the ergonomic layout of a ship’s bridge. User input devices vary by manufacturer. 
 The traveling-wave  slot antennag2 and the surface-wave antennag3 can also be designed to produce a cosecant-  squared antenna pattern.  The shaping of the beam is generally in one plane, with a narrow pattern of conventionai  258INTRODUCTION TORADAR SYSTEMS Although theTaylorpatternwasdeveloped asarealizable approximation totheDolph­ Chebyshev, itdoesnotresemble thetheoretical equal-sidelobe pattern. Valuesof'1arcnot largesothataTaylorpatternexhibitsdecreasing sidelobes overmostofitsrange.Decreasing sidelobes arenotundesired inradarapplication. 
 Instead ofweighting thereceived-signal spectrum toreducethetimesidelobes,itis possible, inprinciple, to·achievethesameaffectbyamplitude-weighting eithertheenvelope of transmitted FMsignalorthereceived signal.InthecaseoflinearFMwithlargepulse­ compression ratio,theamplitude weighting appliedtothetimewaveform isofthesameform astheweighting applied tothefrequency spectrum, forthesameoutput response.24 Amplitude-modulating thetransmitted signalisnotusuallypractical inhigh-power radar Tabletl.tProperties ofweighting functions Peak Mainlobe Sidelobe sidelobe Loss width decay Weighting function dB dB (relative) function Uniform -13.2 0 1.0 IIt 0.33+0.66cos!(nfIB) -25.7 0.55 1.23 III cos!(nIlB) -31.7 1.76 1.65 litJ Taylor(n=8) -40 1.14 1.41 III Dolph-Chebyshev -40 1.35 I 0.08+0.92cos2(nflB)(Hamming) -42.8 1.34 1.50 lit B=bandwidth. since most rnicrowave tubes should be operated saturated; i.e., either full-on or off. Generally,  weighting of the received frequency spectrum has been preferred over either time-weighting  alternative. 
 585–594, 2000. 175. S. 
 The ability to form many beams is usually  easier on reception than transmission. This is not necessarily a disadvantage since it is a useful  method of operating an array in many applications.  The simple linear array which generates a single beam can be converted to a multiple-  beam antenna by attaching additional phase shifters to the output of each element. 
 TION OF SINGLE 
 BANDWIDTH PRODUCT OF PULSE COMPRESSION        SYSTEM "S   UNITY FOR #7 PULSES          $07  PULSE 
 Consequently, it is necessary for the radar receiver to translate the frequency of the echo to that of the filter, in one or more steps, using local oscillators and mixers. Section 3.4 described how spurious responses are generated in the mixing pro- cess. Unwanted interference signals can be translated to the desired intermediate frequency even though they are well separated from the echo frequency at the input to the mixer. 
 and C. P. Wang: Standardization or the Definition or the Radar Ambiguity Function,  IEF.E Trans. 
 (a)line- type Pulser load line, (b)hard-tube pulser pulser isdesigned tooperate with (adequate emission available), (.)hard- minimum tube drop. Itispossible, ‘“be ‘tiser ‘ear ‘aturation however, bychoice ofswitch tubes with proper characteristics, tooperate onsuch aportion oftheir characteristic that thepower regulation near the operating point will beonly about 0.5. The pulser load line, orvariation inoutput voltage and current asa function ofload, isaplot ofload voltage vs.load current (see Fig 10.28). 
 C. Ko, “A fast adaptive null-steering algorithm based on output power measurements,” IEEE  Transactions on Aerospace and Electronic Systems , vol. 29, no. 
  WAS THE WORLDS FIRST TOTALLY SOLID 
 30, pp. 1417-1419, September, 1959.  52. 
 Peeler. G. D. 
 VERTER  TYPICALLY PROVIDE IMPROVED RESOLUTION AND LOWER INSERTION LOSS 'AIN CONTROL ATTENUATORS ARE OFTEN INCORPORATED WITHIN THE RECEIVER AT BOTH 2& AND  )& 2& ATTENUATION IS USED TO PROVIDE INCREASED DYNAMIC RANGE IN THE PRESENCE OF LARGE TARGET RETURNS "Y PLACING THE ATTENUATION AS CLOSE TO THE FRONT END AS POSSIBLE  LARGE SIGNALS CAN BE HANDLED BY MINIMIZING GAIN COMPRESSION  INTERMODULATION  OR CROSS 
 Paraboloid antennas areassumed atboth stations.. 724 RADAR RELAY [SEC. 17.14 TaLE 17.1.—MAxIMuM RANGE OFRELAY SYSTEMS Frequency, Me/see 300 1,000 3,000 10,OOOPower, watts 50 25 05 01Beamwidth, degrees 9-ft paraboloid =27 8 2.7 0.83-ft paraboloid =80 24 8 2.4Free-space range, miles 9-ft paraboloid 196 460 195 2923-ft paraboloid 22 ,51 22 32.5 When one considers the Dower involved, the decrease ofman-made interference with increased frequency, and the privacy and protection from interference provided bynarrow beams, microwave frequencies appear tobethemost desirable. 
 G. Cha:. Patterns md Polarizations ofSi~11uItaneously Excited Planar Arrays on  a Conformal Surface, IEEE Trans., vol. 
 11.5.3  Arbitrary Flat Disk   Again under the assumption that the dimensions are much larger than the wavelengths, one  obtains the corresponding equ ation from Equation (11.21):   € σ=4πAW2 λ2=G⋅AW AW=disk surface (11.22)   The Radar backscattering cross -section of the disk can be obtained from the consideration that  the gain is equal to 4 πAw/λ2 and this is to be multiplied with the area A w, which is taken from  the radiation field.   11.5.4  Radar Cross -Section of Further Simple Bo dies   . Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 104         . 
 Ithas been successfully used inconnection with various types ofdata transmission resulting inslowly varying sine and cosine voltages. Incontrast tothe reproduction ofmechanical motion, the fixed-coil PPI can best use slowly varying polarized direct current. 1Since alter- nating current can easily be rectified togive such voltages, any ofthe methods isapplicable tothis case. 
 TICAL POLARIZATION ,INEAR POLARIZATION OCCURS WHEN  BT   n  AND RIGHT AND LEFT CIRCULAR  POLARIZATIONS OCCUR WHEN  BT   on 7HEN THE MINIMUM IS ABOVE ZERO  THE PEDESTAL  BENEATH IT CORRESPONDS TO THE UNPOLARIZED SIGNAL 4HE OCEAN IMAGE IN &IGURE  A SHOWS THAT THE POLARIZATION IS ESSENTIALLY LIN 
 I £EE Tra11s., vol. A ES-3  Supplement, no. 6, pp. 
 The iritegration-improvernent factor in Fig. 2.24 is in some cases greater than ri, or in  other words, the integration efficiency factor Ei(n) > 1. One is not getting something for  nothing, for in those cases in which the integration-improvement factor is greater than ,I, the  signal-to-noise ratio required for n = 1 is larger than for a nonfluctuating target. 
 LINE LOOP )T IS IMPORTANT TO RECOGNIZE THAT TIMING JIT 
 02& WAVEFORM IS USED  THE CLEAR 
 J. Goldhirsh and J. R. 
 especially when the relationships derived a hove  arc taken into account. In the literature on S/\R, the radar equation is usually written with the  signal-to-noise ratio (S/N) 011 the left-hand side. we· start with the following  p A ian S/N = ----' -"--- (14.14) 4rr}..2kT 0 BF" R4 . 
 LINE CONFIGURATIONS USE THE SWITCHED &%4 PARASITICS AS CIRCUIT ELEMENTS TO INTRODUCE THE NECESSARY PHASE CHANGES 4HE TYPICAL PROCESSING AND CONSTRUCTION SEQUENCE FOR A --)# CHIP IS FAIRLY SIMILAR  AMONG THE 'A!S FOUNDRIES &IGURE   )N THIS FIGURE  THE ACTIVE CHANNEL REGION &)'52%   8 
 Since the DPCA applies the difference pattern in quadrature to the sum pattern to  compensate for phase error and step scan applies the difference pattern in phase to com - pensate for amplitude error, it is possible to combine the two techniques by properly  scaling and applying the difference pattern both in phase and in quadrature. The scaling  factors are chosen to maximize the improvement factor under conditions of scanning  and platform motion. The relationships for a double-delay (three-pulse) AMTI are shown in the phasor  diagram in Figure 3.16. 
 Recovery time was required to be less than 10 µs. The loss  on transmit was 0.15 dB and on receive it was 2 dB. (The receive loss could be reduced to  l dB with application of reverse bias to the diodes.) The device provided from 40 to 50 dB of  protection. 
 530–535, 1984. 143. F. 
 Cumming, I.; Wong, F. Digital Processing of Synthetic Aperture Radar Data: Algorithms and Implementation ; Artech House: Norwood, MA, USA, 2005. 2. 
 1579–1593, 1987. 102. G. 
 262 267.  29. Jakcman. 
 The cost of the transmitter may ultimately be reduced if the waveform can be altered to favor higher duty cycle, since the cost in dollars per average watt of the tran- sistor becomes lower as the duty cycle is increased. As long as this cost differ- ential is large enough to offset the added cost in signal processing to accommo- date long pulses, a less costly transmitter may be realized. Amplitude and Phase Sensitivities. 
 PUT OF THE MATCHED FILTER IS  S    "  FOR LARGE VALUES OF TIME 
 The reflection coefficient from a mismatched antenna with a voltage-  standing-wave ratio o is Jp I = (B - l)/(a + 1). Therefore, if an isolation of 20 dB is to be  obtained, the VSWR must be less than 1.22. If 40 dB of isolation is required, the VSWR must  be less than 1.02. 
 The target SNR is 20 dB; the JNR is 20 dB; the  target DoA is assumed to be evenly distributed in the main-beam angular interval  [–4°, 4°]; details on the numerical parameters used in the study case are in the   reference.73 It is noted that PTB is negligible for F = 0 dB, while PB ≥ 0.9. After a careful performance evaluation of the system depicted in Figure 24.4, it  might be necessary to always resort to either spatial or frequency diversity to improve  the SLB performance. The selection of one of the two diversity techniques depends  on overall system considerations related to the impact of adding more auxiliaries and/ or radiating, with the radar, proper carrier frequencies. 
 Aperture blocking canhemin­ imizedbydesigning theparabolic portionofthetorusasanoffsetparabola,just asinthecase ofaparaboloid. Otherfeed-motion scanners. Thereexistanumherofantennas inwhichthebeamisrapidly scanned overalimitedsectorbythemechanical motionofthefeed.Themotionofthefeedis generally circular. 
 SURE CRAFT 4HESE ARE CALLED RADAR TARGET ENHANCERS  24%  OR ACTIVE RADAR REFLECTORS. 
 In this case, the baseband samples of the  receive data and the reference transmit waveform are passed through fast Fourier  transforms (FFTs), the data FFT outputs are multiplied point-by-point by the complex  conjugate of the reference FFT outputs, and then the result is converted back to the  time domain by an inverse FFT. In general, it is more hardware efficient to perform  time-domain convolution for a small number of coefficients and frequency domain  convolution for a large number (more than 8 or 16) coefficients. ch25.indd   19 12/20/07   1:40:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 RUPTING EFFECTS OF THE IONOSPHERE PROVIDES EVEN GREATER SCOPE FOR EXPLOITING THE SCAT 
 Both tubes show frequency modulation when theheaters arerun ona-c power. The 2K28 was chosen forincorporation into thelocal oscillator unit shown inFig. 16.26. 
 UP 4HE hUPv DIRECTION REFERS TO THE VERTICAL   Y 
 This accuracy can be determined by Tobs, the amount of time over  which the object is observed and by basic parameters of the radar: T = the time between successive detections s  = the accuracy in a particular dimension of interest M = the number of detections used in forming the track N ≅ (Tobs / T ) + 1, which is the number of detection opportunities The velocity accuracy is given by the following equation:72  σσ vTN N N= ×− +  obs12 1 11 2( ) ( )/  (7.39) The dominant design parameters in the equation are the accuracy of the radar and  the observation time. (Better accuracy or longer observation time allows more accurate  measurement of velocity.) Making more detections in the observation time improves  the accuracy but only in a square-root sense. The approach to preventing falsely composed tracks from different objects in a  clutter region, G, is to require enough detections in a tight enough pattern to make  E[NFT], the expected number of false tracks, small. 
 ,______ ___ . [ I p‘1 ( II r I--.— ———______...._ LT (a) A(h) . .> l~lG. 
 These results apply to a ground-based array. If the array is on a ship, the lower limit of the  elevation scan angle rnust be less than 0" to allow for the roll and pitch of the ship. (A value of  - 20' rnigltt be a typical requirement.) The optirnurn tilt angle of the array would be different  than if the lower lirnit were 0". 
 IES SHOWN IN &IGURE  4HE DIAMETERS AND PROJECTED AREAS OF THE OBJECTS ARE IDENTI 
 Lewis and I. D. Olin, “Experimental study and theoretical model of high-resolution  backscatter from the sea,” Radio Sci ., vol. 
 Low-duty-cycle systems, therefore, must use range gating to optimize performance. In addition to retaining doppler resolution capability the range-gated system provides range resolution. Active Seekers.4'16 Active seekers can provide increased firepower as well as fire-and-forget (or launch-and-leave) operation. 
 ON VIEW OF THE  & 
 8, pp. 132- 134, 1955.  14. 
 xv PREFACE Radar is an important example of an electrical engineering system. In university engineering courses, the emphasis usually is on the basic tools of the electrical engineer such as circuit design, signals, solid state, digital processing, electronic devices, electromagnetics, automatic control, microwaves, and so forth. But in the real world of electrical engineering practice, these are only the techniques, piece parts, or subsystems thatmake up some type of system employed for a useful purpose. 
 [ CrossRef ] 39. Erten, E.; Rossi, C. The worsening impacts of land reclamation assessed with sentinel-1: The rize (Turkey) test case. 
 #  %)+ OPERATED OVER A FREQUENCY RANGE FROM  TO  -(Z  BANDWIDTH   WITH A PEAK POWER OF  -7 AND AN AVERAGE POWER OF  K7  AND AN EFFICIENCY OF  %)+ DEVICES HAVE BEEN OF INTEREST FOR MILLIMETER 
 2. They use a sufficiently high pulse repetition frequency (PRF) to be ambig- uous in range. 3. 
 However, if the only  difference between pulses is absolute phase (not intrapulse variations pulse to pulse),  some mitigation is possible. One method of compensating for small variations in the  phase of transmitter pulses follows. Lincoln Laboratory changed the original TDWR  waveform to an MTD type waveform. 
 Some research applications require faster scanning. These applications in- clude the study of finer-scale storm features, interactions between the kinematics and hydrometeor growth processes in the storms, and studies of electric-charge separation in clouds. Brook and Krehbiei76 were the first to discuss a very-rapid- scanning radar (although nondoppler) for effectively obtaining snapshots of con- vective storms. 
 ENCE SIGNALS ARE PROVIDED FOR THE TWO LINEAR 
 The resultant antenna  beam pattern points in the positive z-direction. For a round reflector of diameter D, the  edge or rim is a circle and the edge dimensions are on this circle defined by  x yD edge edge2 22 4+ =  (12.2) This reflector is shown in Figure 12.1. One frequently is interested in the angle a from the z-axis to points on the reflector  surface:  α=+    222 2 arctanx y f  (12.3) ch12.indd   3 12/17/07   2:30:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Rept. 171, Jan. 8, 1958. 
 Glazer, “Waveform analysis of transmissions of opportunity for passive  radar,” in Fifth International Symposium on Signal Processing and its Applications , Brisbane,  Australia, August 1999, pp. 511–514. 126. 
 F. Fabry and R. J. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.44  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 The monopulse null position is unaffected by the behavior of the subarrays as long  as they all respond in the same way. The null position is determined only by the time- delay networks behind the subarray and corresponds to the array-factor null, which is  unaffected when multiplied by the subarray pattern. 
 Torestore the energy tothe magnetic field, itisnecessary either topass large steady currents through the inductance between pulses, ortouseafairly complicated grid-modulating circuit whose function istostart thecurrent flowing through theinduct- ance ashort time before the moment ofinterruption. Ineither case, power losses intheswitch and auxiliary equipment are much larger than those inpulsers ofcomparable output using electro- static storage ofenergy. .4saresult, theuseofpulsers employing elec- tromagnetic energy storage hasbeen limited tospecial applications (such astrigger circuits) where itisnecessary toobtain avery high ratio between the pulse voltage and the supply voltage orwhere the load is mostly capacitive. 
 Scattering and diflractiorr are variations of the same physical process.15 When an object  scatters an electromagnetic wave, the scattered field is defined as the difference between the  total field in the presence of the object and the field that would exist if the object were absent  (but with the sources unchanged). On the other hand, the diffracted field is the total field in the  presence of the object. With radar backscatter, the two fields are the same, and one may talk  about scattering and diffraction interchangeably. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft.  MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 This limitation leads to the need for another mode interleaved with RGHPRF. 
 65. Leary, F.: Researching Microwave Health Hazards, Electronics, vol. 32, no. 
 Proctor, and L. D. Schultz: Predicting Long- Term Operational Parameters of High-Frequency Sky-Wave Communications Sys- tems, ESSA Tech. 
 Riis  accuracy decreases as the angle of intersect OF fo hhe  two constant-range circles through the target COCTCOESS mac |  The combination of Gee and H in G-Hisa lappy & try...  for in many operational circumstances Gee cin be US eg  for the general navigation, and then the sjil¢™ €—2eaq,  switch over so that the H{ part can be wed forthe & aromaqy  run-in.  Depending, as these systems do, on tht prec# me  measurement of the time differences in the arival aoe  pulses, either direct or triggered, Gee and the kindras «cq  systems have set a new standard of accusty in rad wo  navigation, but there are practical difficilis in usiraague  these systems for civil flying. 
 57 }Vhen j,<f~,the system asoutlined must bemodified byplacing infinite-attenuation filters after the second detector. The filters are designed toremove j,completely, ~vhile leaving allbut closely adjacent frequencies undisturbed. Inprinciple, this isnodifferent from the infinite-at tenuat ionfilters already present toremove the d-csignals due toclutter. 
 127 5.2 Transmitted Spectra. 129 5.3 Effect ofTarget. 130 5.4 Class ofSystems Considered 131 55 Utility ofCw Systems. 
 Ifathree-pulse code isused, a similar argument applies forthethird pulse and anadditional factor of 2TN will come intogive 4T2N3 asthe number ofrandom replies per second. The argument also applies totwo-frequency interrogation. IIere thenumber ofrandom interrogations will be2TNIN2 ifNIand Nzare the respective random rates atthe two frequencies, and the beacon is made sothat thetwo pulses have toarrive inacertain order fortrigger- ingtooccur. 
 An example of a grid-controlled tube that could be suitable for high-power radar applica­ tion at UHF is the Coaxitron.22 It has wider bandwidth and better performance than conven­ tional UHF grid-control tubes because it integrates the complete RF input and output circuits  and the electrical interaction system within the vacuum envelope. The RCA A15193, for  example. operates from 406 to 450 MHz with 1.5 MW peak power, a duty cycle of 0.0039, 47  percent plate efficiency, and 13 dB gain. 
 BUTION GENERALLY FITS THE AVERAGE OF SEVERAL DROP 
 Ship targets recognition by ships’ feature in SAR image. J. Shaanxi Norm. 
 #/5.4%2-%!352%3   Ó{°ÈÇ  3 , *OHNSTON  h4HE %##- IMPROVEMENT FACTOR %)&  ILLUSTRATION EXAMPLES  APPLICATIONS  AND  CONSIDERATIONS IN ITS UTILIZATION IN RADAR %##- PERFORMANCE ASSESSMENT v  )NT #ONF 2ADAR   .ANJING #HINA   .OVEMBER n    PP n  * #LARKE AND ! 2 3UBRAMANIAN  h! GAME THEORY APPROACH TO RADAR %##- EVALUATION v  0ROC  OF )%%%  )NT 2ADAR #ONF  !RLINGTON 6!   53!  -AY n    PP n  , .ENGJING  h&ORMULAS FOR MEASURING RADAR %##- CAPABILITY v  )%% 0ROC  VOL   PT &    PP n  *ULY   , .ENGJING  h%##- EFFICACY ASSESSMENT IN SURVEILLANCE RADAR ANALYSIS AND SIMULATION v  )23    )NT 2ADAR 3YMP  -UNICH  'ERMANY  3EPTEMBER n    PP n  $ ( #OOK  h%#-%##- SYSTEMS SIMULATION PROGRAM  ELECTRONIC AND AEROSPACE SYSTEMS  RECORD v )%%% #ONV 2EC %!3#/.   3EPTEMBER n    PP n  3 7ATTS  ( $ 'RIFFITHS  * 2 (OLLAWAY  ! - +INGHORN  $ ' -ONEY  $ * 0RICE  ! -  7HITEHEAD  ! 2 -OORE  - ! 7OOD  AND $ * "ANNISTER  h4HE SPECIFICATION AND MEASURE 
 W.. A. W. 
 (ILL "OOK #OMPANY    - ) 3KOLNIK  )NTRODUCTION TO 2ADAR 3YSTEMS  .EW 9ORK -C'RAW 
 The Principle of Interferometric DEM-Assisted High Precision Imaging Method for ArcSAR From the analysis of previous section, the ArcSAR imaging result on the reference plane is a ﬀected by the terrain ﬂuctuation. For acquiring high precision ArcSAR image, an interferometric DEM-assisted high precision imaging method for ArcSAR is proposed in this paper. The interferometric ArcSAR is 137. 
 VALS  SO THAT SUCH NOISE PULSES CAN APPEAR IN ANY PART OF THE RANGE SWATH 7HEN OBSERVED OVER A SUFFICIENT NUMBER OF SAMPLES  THE NOISE PULSES WILL OCCUPY ALL PARTS OF THE RANGE SWATH IN ONE SAMPLE OR ANOTHER 4HE AZIMUTH PROCES SOR FORMS THE SUM  OF THE NOISE POWER FROM ALL SAMPLES WITHIN ONE SYNTHETIC APERTURE LENGTH 4HAT SUM WILL BE EQUAL TO THE TOTAL NOISE POWER IN THE APERTURE  WHICH IS PROPORTIONAL TO THE AVERAGE JAMMER NOISE POWER !LSO  IN THIS CASE  THE SPECKLE DIMENSION WILL APPEAR STRETCHED IN RANGE  JUST AS IN THE SPOT JAMMER CASE (OWEVER  THE RANDOM PULSE JAM 
 POLARIZED ENERGY IS ZERO WHEN THE SOURCE IS PRE 
 The world’s first practical  radar scheme was drawn up on paper as a piece of pure  mathematics and scientific reasoning. Without even  bothering to draw a circuit diagram, Watson-Watt  showed how radar could be made to work. This is an  outstanding example of pure reasoning over practical  proof, but the responsible member of the Air Council  was not impressed, and said in effect, “‘ Numerical con-  siderations can be pretty much what scientists like to  make them. 
 The equivalent  solid angle of the antenna ΩAnt = 4 π/G is >> ΩB.  By aligning the antenna to the noise source,  the antenna noise temperature TAnt can be calculated within good a approximation according to  equation (6.9):  € TAnt=TBΩB ΩAnt (6.9)  An example for such a discrete noise source is the sun  € ΩH=6,5⋅10−5(sr) (solid angle in st e- radian).  The noise temperature of the sun lies in the frequency range from 2GHz at approx i- mately € 10000°K. 
 OilMilitary Llccfrtmics, PI'..10·.14,1%0. 109.Skolnik. M.I.:Nonuniform Arrays,chap.6of"Antenna Theory,pI.I."R.E.CoJ/inandF.J.Zucker (cds.).McGraw-Hili BookCo.,NewYork,1969,p.231. 
 TOR SYSTEMS 4WO OF THE MORE WELL 
 The reflector was fabricated of three triangular plywood panels,  metallized to enhance their surface reflectivities. The aperture exposed to the radar  was, therefore, an equilateral triangle, as shown in Figure 14.9. The eight patterns in  Figure 14.8 were measured with the plane of the aperture tilted above or below the  line of sight by the angle f. 
 The seven outputs are combined by using a single 7:1 air stripline combiner with 1.0-in ground-plane spacing. The 130-kW outputs of the two 56:1 combiners are combined in a single 2:1 isolated hybrid that is manufactured by using 31Xs-Jn coaxial transmission line. The adver- tised losses of the 2:1 and 56:1 combiners are 0.1 dB and 0.25 dB, respectively. 
  " "9 !NTENNAS !NTENNA MAXIMUM SIDELOBES ARE SPECIFIED FOR 3/,!3 AND NON 
 482 THERECEIVIA’GSYSTEM-INDICATORS [SEC.132 saturate too quickly. The number ofoverlapping pulses (which is often large) isgiven foraPM bytheexpression NS/ur atthecenter of thearc, where NisthePRF, Sisthespot size, uistheangular velocity ofthescan, and risthedistance from theorigin ofthedisplay totheecho spot. Thus fora30-sec scan and aPRF of400 (see Sec. 
 Caponi, C. L. Hindman, B. 
 As a rough rule of thumb, the intet~sity of tlie etiergy  $ 80-  er L  3 +  k 60.- a  D - 0  -40- U C  % U - .t ;5 20- -  0 I I I 1 Figure 7.8 Efficiency of a paraboloid as a function of  0 20 40 60 80 100 the half angle subtended by the paraboloid at the focus.  Holf angle subtended by paraboloid at focus (From C. ~utler,~ Proc. 
 Meitzler: Attenuation of Longitudinal and Flexural Wave Motions in Strips, IEEE Trans., vol. SU-12, pp. 65-70, June 1965. 
 Receiver noise generally limits the sensitivity of most microwave radars.  Raising the noise level by external means, as with a jammer, further degrades the sensitivity of  the radar. Noise is a fundamental limitation to radar performance and therefore can bi: an  dfoctive countermeasure. 
 CHAPTER 14 CW AND FM RADAR William K. Saunders Formerly of Harry Diamond Laboratories 14.1 INTRODUCTION AND ADVANTAGES OF CW The usual concept of radar is a pulse of energy being transmitted and its round- trip time being measured to determine target range. Fairly early it was recognized that a continuous wave (CW) would have advantages in the measurement of the doppler effect and that, by some sort of coding, it could measure range as well. 
 In many traditional cases, such as image classiﬁcation with a cats and dogs dataset, they usually have tens of thousands images for training and testing. When dealing with these problems, though using random crop may lose some information, but they could still keep the main information of images. This information is sufﬁcient for further work. 
 -"1, 
 FLYING TARGETS !S AN EXAMPLE  &IGURE  SHOWS THE MAXIMUM CLUTTER 
 Then, the refractive index, or refractivity, of the  atmosphere of these atmospheric paths may be determined.17 Refractivity is a func - tion of temperature, pressure, and moisture content. Consequently, if surface tem - perature and pressure are independently available, as they frequently are, then the  refractive index measurements may be converted to spatial fields of water vapor in the   surface boundary layer. Such water vapor measurements are critical for obtaining  accurate forecasts using numerical models and simulations of the atmosphere.150 This  experimental measurement technique can be used to ranges of about 40 km where the  Earth’s curvature prevents routine observation of ground clutter targets and is being  considered for operational use in Nexrad. 
 I. Marcum extensively developed the sta- tistical theory of detection with the aid of machine computation, referencing North's report. He computed probabilities of detection as a function of a range parameter related to signal-to-noise ratio, for various numbers of pulses inte- grated and for various values of a false-alarm parameter which he designated false-alarm number. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 points from the mean plane. 
 117,156 Braggscatter,480.534 Branch-type duplexer. 360 Brewster's angle,444 Brightband.502 Brightdisplays, 357-358 Brightness temperature. 461-462 Burnout. 
 TRAFFIC 
 STATE TRANSMITTER WAS SUPPOSED TO OCCUPY THE SAME FLOOR SPACE AS THE VACUUM TUBE TRANSMITTER  BUT IT OCCUPIED ABOUT THE SAME FLOOR SPACE AS THE ENTIRE !.303 
 At L band and below, the differ - ences between MY and FY ice are small even in winter. This means that imaging  radars can easily distinguish ice types by intensity alone at the higher frequencies  in winter but not in summer. This fact is the basis for operational ice-monitoring  systems by the Soviet Union [using the Toros Ku-band side-looking airborne radar  (SLAR)]154 and Canada155 (using a modified X-band APS-94 SLAR and the STAR-1   X-band SAR). 
 ) ch23.indd   8 12/20/07   2:21:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 
 STATE v IN TH  )NTERNATIONAL 6ACUUM %LECTRONICS #ONFERENCE  !PRIL n    PP n   2 3YMONS  h-ODERN MICROWAVE POWER SOURCES v  )%%% !%33 3YSTEMS -AGAZINE   PP n   *ANUARY    4 3ERTIC  h)DIOSYNCRASIES OF 474 AMPLIFIERS v PRESENTED AT 4HE &UTURE OF %LECTRONIC $EVICES  #ONFERENCE  )NSTITUTE OF 0HYSICS  -ARCH      - (ANCZOR AND - +UMAR  h 
 NALS  AND NO COMPARATORS ARE USED 'ENERALLY  MODE COUPLING DEVICES CAN GIVE GOOD  PERFORMANCE IN SEPARATING THE SYMMETRICAL AND UNSYMMETRICAL MODES WITHOUT SIGNIFI 
 6.2/,, stable oscillation can occur in the rr mode without the need  for straps. Since there arc no straps, the rising-sun geometry is more suitable for the shorter  wavelengths than are conventional resonators.  Coaxial ma~netron. 
 PROVEN FOR #ANADAS 2!$!23!4 
 3!2 OPERATED AT THREE BANDS # AND , 53!  AND 8 CONTRIBUTED THROUGH AN INTERNATIONAL PARTNERSHIP WITH 'ERMANY AND )TALY  $ATA FROM 3)2 
 Ê  Ê-/  /9Ê , 
 A typical metal space-frame radome of this type might have  266INTRODUCTION TORADAR SYSTEMS Figure7.29Rigidradomeforground-based antenna. (FromDavisandCohen,! Bcourtes}'Electronics wul MITLincolnLaboratory.) . 55-ft-diameter radome showninFig.7.29isdesigned sothattheplasticflangesbetween thepanelstaketheloadwhiletheplasticpanelsactasthindiaphragms whichmerelytransmit wind~pressure loadstotheframework towhichtheyareattached. 
 The entire clutter spectrum can be calculated for each range gate by Eq. (17.2) if the antenna pattern is known in the lower hemisphere. In preliminary system design, the exact gain function may not be known, so that one useful approximation is that the sidelobe radiation is isotropic with a constant gain of GSL. 
 Now we want to study, what kinds of factors are expr essed in  this radar equation.                Antenna Gain   The antenna gain of the radar is a known value. This is a  measure of the antenna's ability to focus outgoing energy into  the directed beam. 
 CONTROLLED COHERENT MASTER OSCILLATOR #/-/   WHICH DETERMINES THE TRANSMITTED FREQUENCY OF THE RADAR 4HE #/-/ IS SLAVED TO  &)'52%  .ORMALIZED BORESIGHT 
 The effect of this phase differential on the IF outputs of the mix- ers is a +90° shift in one sideband and a -90° shift in the other. The IF hybrid, adding or subtracting another 90° differential, causes the high-sideband signals to add at one output port and to subtract at the other. Where wide bandwidths are involved, the IF hybrid is of the all-pass type. 
 R.. arid C'. M. 
   PP n  !PRIL   0 3WERLING  h0ROBABILITY OF DETECTION FOR FLUCTUATING TARGETS v  )%%% 4RANSACTIONS ON )NFORMATION  4HEORY  VOL )4 
 CM  WAVELENGTH   WITH  
 SIBLE FREQUENCY SELECTION IS SET BETWEEN  AND  -(Z  AND ANTENNA RADIATION IS NOT CONSIDERED BELOW AN ELEVATION ANGLE OF  n 4HE ANALYSES WERE MADE FOR A RADAR OFF  THE MID 
 In Formula (15), optimization solving can be performed by applying the OMP method which not only guarantees reconstruction accuracy, but also has high computational efﬁciency. 3. Joint Sparsity Constraint Near-Field 3-D Imaging of Inisar Based on CS3.1. 
 Rummler, “Introduction of a new estimator for velocity spectral parameters,” Tech. Memo  MM-68-4121-5 , Bell Telephone Laboratories, Whippany, NJ, 1968. 85. 
 3.21.—.4irport runways atBedford, Mass. Wavelength =1.25cm,O.SObeam, altitude 1500 ft,radius 3nautical mi. Theblank sectors tothesouth areshadows castby thewheels oftheairc,aft. 
 ETERS  THE TARGET HAS MIGRATED OVER SIX RANGE CELLS 4HIS IS THE CAUSE FOR THE BROADEN 
 Or we can arrange  the circuit values so that after initial charge the con-  denser does not become discharged until another small  voltage change takes place, and this voltage change can  come from another circuit, so that the time~base display  . 76 HOW RADAR WORKS  on the CRT depends each time on this additional  _ triggering circuit.  For lower frequencies the discharge through a thyra-  tron is satisfactory. 
 Skolnik. M. I.: Survey of Phased Array Accomplishments and Requirements for Navy Ships,  ·· Phased Array Antennas," A. 
 6.U.S.Patent1,981,884, "System forDetecting ObjectsbyRadio,"issuedtoA.H.Taylor,L.C.Young, andL.A.Hyland,Nov.27,1934. 7.Vieweger, A.L.:RadarintheSignalCorps,IRETrans.,vol.MIL-4,pp.555-561, October, 1960. 8.OriginsofRadar:Background totheAwardsoftheRoyalCommission, Wireless World,vol.58, pp.95-99,March,1952. 
 Riblct, vol. 35. pp. 
 24,  pp. 128- 13 1, February, 1953.  21. 
 SIDEBAND NOISE  THE SUM OF THE POWER IN BOTH THE UPPER AND  LOWER SIDEBANDS  BUT MORE TYPICALLY REPORTED AND SPECIFIED AS SINGLE SIDEBAND 33"  VALUES $OUBLE 
 Performing the sampling analysis  described previously, we discover that setting the sample rate to the two-sided signal  bandwidth of 80 MHz would produce aliasing. However, a 100 MHz sample rate does  not cause aliasing and is used on the second line of the figure. Sampling the input  signal at 100 MHz replicates the signal spectrum at 100 MHz intervals as shown on  line 3. 
 R. Nevin, “AN/APG-67 multimode radar performance evaluation,” in IEEE NAECON 1987 , p. 317. 
 L., 27,  II2  Oscillator; Numans, 94  Oscillograph, Cossor, 77-78 a _*  PEAK POWER, 51  Permanent echoes (PE’s), 42  Plan position indicator (PPI),  26, IO7—108 |  Polfard, P. E., 26  Pollux, H.M.S., tests in, 130  Puckle, O. S., 77, 99  Pulse recurrence frequency  es (PRE), 50 Pulse-shaper, 85  QM (DEcCA), 127  ‘RADAR,’ meaning of the word,  32  Radio waves, speed of, 3  Randall, Professor J. 
 LAR POWER TRANSISTORS  OPERATED #LASS 
 It is significant that the extended targets are no longer very extended. The face of a mountain at 10 mi from 5 to 7 o'clock is only a line. If the MTI system were incapable of displaying an aircraft while it was over the mountain face, it would display the aircraft on the next scan of the antenna because the aircraft would have moved either farther or nearer. 
 RECEIVER ,/3 IS NOT  REQUIRED UNLESS PERIODIC CLOCK SYNCHRONIZATION IS IMPLEMENTED OVER THE DIRECT PATH 4HE TRADITIONAL METHOD FOR CONVERTING TARGET RANGE SUM INTO TARGET RANGE FROM THE  RECEIVER  22  IS   222 , 22 ,242 42 2 
 BASED 3HIP 
 BAND 6OLUME 3EARCH 2ADAR 632  PHASED ARRAY SEE  &IGURE   PROVIDES SEARCH AND !!7 CAPABILITY TO THE $UAL "AND 2ADAR 3YSTEM FOR $$8  )T HAS  RADIATING ELEMENTS WITH A 42 MODULE PER ELEMENT !LTHOUGH THE ACTIVE RADIATING APERTURE IS APPROXIMATELY CIRCULAR  THE CORNERS HAVE BEEN FILLED IN .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°ÈÎ WITH TERMINATED ELEMENTS TO FORM A RECTANGULAR APERTURE FOR PURPOSES OF MINIMIZING  ANTENNA RADAR CROSS SECTION !LL ACTIVE COMPONENTS ARE ACCESSIBLE FROM THE REAR FOR EASE OF MAINTENANCE ABOARD SHIP 'ROUND 
 North2 gives the exact func- tions that apply for single-pulse detection with a linear rectifier as detector and the approximations that apply when many pulses are integrated. The density functions appropriate to other situations, e.g., square-law detection and fluctua- tion of signals, are given by various authors.3"10 The decision as to the acceptable level of false-alarm probability is usually made in terms of a concept called false-alarm time, which will here be defined as the average time between false alarms. Other definitions are possible; Marcum3 defines it as the time for which the probability of at least one false alarm is 0.5. 
 (7.31).. 264 INTRODUCTION TO RADAR SYSTEMS  When the second term can be neglected (as when the correlation interval is small compared to  the diameter of the antenna and the phase error is not too large), the gain can be written  where c is the effective reflector tolerance measured in the same units as A; i.e., it is the rms  surface tolerance of a shallow reflector (large focal-length-to-diameter ratio) which will pro-  duce the phase-front variance d2. For a given reflector size D, the gain increases as the square  of the frequency until the exponential term becomes significant. 
 The out-of-phase components of mismatch reflections from the aperture and  of other unbalanced reflections are absorbed in the terminations. The in-phase and FIGURE 13.31  Series-feed networks ch13.indd   48 12/17/07   2:41:00 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 SIGHT SITUATIONS BECAUSE OF ITS LOWER FREQUENCY )T QUICKLY REPORTS A TARGETS CHANGE IN HEADING OR COURSE  INCLUDING RATE OF TURN DATA  IF IT IS AVAILABLE ON THE TARGET VESSEL !)3 IS NOT AFFECTED BY SEA CLUTTER AND CAN REPORT ABSOLUTE POSITION ACCURATELYTO NORMALLY BETTER THAN  METERS OR EVEN A METER OR TWO  IF REPORTING DIFFERENTIAL '.33 
 841–851, 2005. 183. G. 
 A detailed analysis of the accuracy of the phase-in-space technique is not available, but in  one implenientation it has been said3' to have a potential elevation accuracy of about 0.2".  Multipath reflections can also degrade the accuracy of this method, but since the phase-in-  spacc teclitlique employs rnt~ltiplc hen~ns to shape its elevatiot~ pattern. it might be possible to  control the radiation so as ro illurnir~ale tlle surface witli less energy than the conventional  fan-bearn antenna. 
 (after R. Coopermanr57 © Fifth International Conference on Information Fusion, vol. 2, 2002 )0.5 −0.511.5 00.5 −0.511.5 00.5 −0.511.5 0 1200 1000 800 600 400 200 0 1200 1000 800 600 Time (sec)400 200 050 01200 1000 800 600 400 200 01200 1000 800 600 400 200 0Probability in Re-entryTarget Acceleration (g’s)Probability in BoostProbability in Exo-Flight ch07.indd   37 12/17/07   2:14:35 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 J. Baker, and S. Watts, “Maritime surveillance radar Part 1: Radar scattering from  the ocean surface,” IEE Proc ., vol. 
 The azimuth angle 6, with minimum range as the 0° azimuth reference point, starts at about -90° and ends at about 4-90°, with its maximum rate of change 6(0 at minimum range. For target param- eters of a velocity of 500 kn, crossover range of 1000 yd, and altitude of 1500 ft, the derivatives of azimuth angle are 6 max = 18.6°/s, 6max = 4°/s2, and 0max = 4.2°/s3. Choosing example servosystem constants Kv = 100, Ka = 111, and Kj = 1111 results in a tracking-lag function ^ 0(0 8« e(r) a(f\ •=. 
 (2). As described in Section 4.1, with densely distributed ponds around the upper stretch of the highway, mucky clay and silt dominated the geological content of the clay, and the soft soil layer of the upper segment was relatively thicker (with a thickness of 12.93–19.50 m). In addition, the water system around this stretch was well-developed and, thus, the ground subsidence was more obvious. 
 It is simply a function computed from the reciprocal of a true adapted antenna pattern. Superresolution and adaptive antennas are identi- cal mathematically, use the same algorithms, and have identical hardware. Roughly speaking, the difference is that one produces a pattern with the nulls down (adaptive antenna for jammer cancellation) and the other with the nulls up (superresolution of jammers). 
 £n°£-«>Vi >Ãi`Ê,iÌiÊ -iÃ}Ê,>`>ÀÃ ,°Ê iÌ Ê,>iÞ *OHNS (OPKINS 5NIVERSITY !PPLIED 0HYSICS ,ABORATORY £n°£Ê * 
 Very high powers may be gener - ated from a multiplicity of amplifiers distributed across the aperture. Electronically  controlled array antennas can give radars the flexibility needed to perform all the vari - ous functions in a way best suited for the specific task at hand. The functions may be  programmed adaptively to the limit of one’s capability to exercise effective automatic  management and control. 
 Figure 2. Inverse synthetic aperture radar (ISAR) scenario: asteroid’s kinematics and geometry. 5. 
 BANDWIDTH PROD UCT AND PULSE COM 
 For this reason, control ofthe width ofthe reply arcs bydecreasing the interrogating power would be desirable. Inany case, iflarge traffic istobeexpected, itisdesirable tousesome sort ofinterrogation coding toensure that beacons will betriggered only bythose radar sets that want tolook atthem, and not byones uninter- ested ingetting replies from thebeacon. The effectiveness ofmultiple-pulse interrogation codes incutting down unwanted beacon replies can beseen asfollows. 
 DETECTION CIRCUITRY AS WELL AS TRANSMITTER TRIGGER AND PRE 
 ING IN BETTER RADAR SENSITIVITY &OR ANY GIVEN SET OF RADAR PARAMETERS   -. TRACK  FORMATION CRITERION  AND PROBABILITY DISTRIBUTION OF CLUTTER AMPLITUDES  THERE EXISTS  AN OPTIMUM FALSE 
 D. Burnside, C. W. 
 B., and P. Swerling: Sequential Detection in Radar with Multiple Resollition Elements,  IRE Trans., vol. IT-8, pp. 
 105. pp. 213 220. 
 02& PULSE DOPPLER WAVEFORM CYCLES THROUGH  . UNIQUE 02&S IN A PROCESSING DWELL  . TYPICALLY BEING  TO   4HE MEDIUM 02&S  GENERALLY COVER NEARLY AN OCTAVE IN FREQUENCY FOR GOOD DOPPLER VISIBILITY AND GROUND MOVING TARGET REJECTION (OWEVER  HIGH 
 1966.  83. Cantrell. 
 BASE EXTENDS OUT TO PERHAPS TEN MILES 4HE TERRAIN DATABASE CANNOT BE COMPLETELY CURRENT AND MAY CONTAIN CERTAIN SYSTEMATIC ERRORS &OR EXAMPLE  THE DATABASE CANNOT CONTAIN THE HEIGHT OF WIRES STRUNG BETWEEN TOWERS OR STRUCTURES ERECTED SINCE THE DATABASE WAS PREPARED &OR THE LOWEST POSSIBLE FLIGHT PROFILES WITH LESS THAN  n PROBABILITY OF CRASH  PER MISSION  THE PRESTORED DATA IS MERGED AND VERIFIED WITH ACTIVE RADAR MEASUREMENTS ,OW CRASH PROBABILITIES MAY ALSO REQUIRE SOME HARDWARE AND SOFTWARE REDUNDANCY )N ADDITION  AS THE AIRCRAFT FLIES DIRECTLY OVER A PIECE OF TERRAIN  COMBINED TERRAIN PROFILE IS VERIFIED BY A RADAR ALTIMETER FUNCTION 4%2#/-4%202/-  IN THE 2& AND PROCESSOR COMPLEX 5SUALLY THE PRESTORED DATA IS GENERATED AT THE REQUIRED RESOLUTION BEFORE A MISSION FROM THE WORLDWIDE DIGITAL TERRAIN ELEVATION DATABASE $4%$  3EA 3URFACE 3EARCH  !CQUISITION  AND 4RACK  3EA SURFACE SEARCH  ACQUISITION   AND TRACK ARE ORIENTED TOWARD THREE TYPES OF TARGETS SURFACE SHIPS  SUBMARINES SNORKEL 
 Ingeneral, thetwo-frequency MTIdoesnotofferanyobvious netadvantage over properly designed single-frequency MTIsystems formostMT[radarapplications. AreaMTI.ThisformofMTIdoesnotusedoppler information directlyasdotheotherMTI techniques discussed inthischapter. TheearlyareaMTIsystemsstoredacOl\lplete scanof radarvideoinamemory, suchasastoragetube,andsubtracted thestoredvideoscantoscan. 
 Thismaybeaccomplished withreservetransmitter powerorbydwelling longerinthedirection ofthejammer. Dwelling longer Oilatargetreduces thedatarate,andthuscandegrade theoverallradarperformance. A significant reduction indatarategenerally isnotdesirable. 
 121. J. Kerkmann, Review on Scatterometer Winds , Darmstadt, Germany: European Organization for  the Exploitation of Meteorological Satellites EUMETSAT, 1998, p. 
 STANT BRIGHTNESS AND DYNAMIC RANGE $EPENDING ON GRAZING ANGLE  AMBIGUOUS RETURNS MAY COMPETE WITH THE REGION TO BE IMAGED /FTEN  A COMBINATION OF SENSITIVITY TIME CONTROL 34#  AND PULSE TO PULSE PHASE CODING IS USED TO REJECT MULTIPLE TIME AROUND ECHOES -4!%      4HE AMOUNT OF PRESUMMATION 02%35-  AND POST DETECTION  INTEGRATION 0$)  AS A FUNCTION OF BEAM POSITION OFF THE VELOCITY VECTOR IS SHOWN IN THE LOWER RIGHT OF &IGURE  &OR EACH DIFFERENT ANGLE  THERE IS A DIFFERENT DOPPLER SPREAD ACROSS THE BEAM 4HEREFORE  IN ORDER TO MAINTAIN A CONSTANT BEAM 
 DIVERSE  AND WAVELENGTH 
 HAND SIDE ANTENNA IS A LOW 
 Ince, and D, H. Temme: A Solid State "Flux-Drive" rontrol Circuit for  Latching-Ferrite-Phaser Applications, Microware J., vol. 15, pp. 
 Asignificant restriction inattempting toutilizesolid-state devicesasadirectreplacement fortheconventional microwave-tube transmitter istherelatively lowpoweravailable froma singlesolid-state deviceorevenasinglepowermodule.Thesolid-state deviceormodulefinds application inthoseradarswherehighpowerisnotneeded,suchasaircraftaltimeters, CW policespeedmeters,andshort-range intrusion detectors. Higherpowercanbeobtained by combining theoutputsofalargenumberofindividual devices.Unfortunately, formanyradar applications hundreds orthousands ofdeviceswouldhavetobeemployed inordertoachieve therequisite powerlevels.Theresultant losswiththecombining ofalargenumberofdevices insomemicrowave circuitscansometimes negatetheadvantage achieved bycombining. Thus asadirectreplacement forconvention~l microwave tubes,solid-state deviceshavebeen limitedtolowormoderate powerapplications. 
 1578–1588, 1998. 92. J. 
 /N 
 Considerations here are that the doppler straddling loss of the filter bank be minimized   FIGURE 2.53  Six-pulse filters for targets at ( a) f T = 0.5, ( b) Ft = 0.3, f T = 0.8, and ( c) combined response  of complete bank of five six-pulse filters (a) (b) (c) (d) ch02.indd   53 12/20/07   1:45:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 This minimizes the required A/D converter -sampling rate.   Do not double the spectral ripple by including the amplitude characteristics of the  matched filter.  This could degrade the achievable time side lobes by as much as 6  dB. 
 (7.36) corre-  sponds to a diameter of about 1600 wavelengths for maximum gain. The beamwidth of such an  antenna would be about 0.04" with a gain of about 68 dB.  In practice, the construction tolerance of an antenna is often described by the "peak"  error, rather than the rms error. 
 The necessity for attenuation or  severs in the structure, as mentioned above, tends to make the traveling-wave tube less efficient  than the klystron. The slow-wave structure can also provide a limit to TWT capability. It  seems that those slow-wave structures best suited for broad bandwidth (like the helix) have  poor power capability and poor heat dissipation. 
 P. Beckmann and A. Spizzichino, The Scattering of Electromagnetic Waves from Rough Surfaces ,  New York: Macmillan Company, 1963. 
 20.8 in terms of a normalized sensitivity factor k = KKlL versus normalized sine-space angle-of-arrival u = L/\ sin 6. The elevation w-space angle of arrival u of target energy is referenced to the crossover point halfway between the beams. Various beam separations in u space are illus- trated. 
 10.1 and 10”2) byconducting bars called strapsSwhich connect alternate segments. Power isextracted from one resonator, one method being theuse ofacoupling loopLwhich forms apart ofthe output cir- cuit. The combination ofresonant cavities, end spaces, straps, and out- put circuit iscalled theresonant system. 
 TERED AT 2& TO PREVENT THEIR REACHING THE MIXER )F SUFFICIENT FILTERING CANNOT BE APPLIED PRIOR TO THE MIXING PROCESS  SPURIOUS PRODUCTS THAT FALL WITHIN THE OPERATING BAND WILL NO LONGER BE FILTERABLE  WHICH WILL SERIOUSLY DEGRADE SYSTEM PERFORMANCE 3PURIOUS RESPONSES NOT PREDICTED BY THE CHART OCCUR WHEN TWO OR MORE 2& INPUT SIG 
 Thomason are gratefully acknowledged. priate for aircraft and ship targets. In the upper left the ray-path sketch shows that at higher-elevation radiation angles the rays escape, causing a skip zone of range coverage, that energy is returned to the earth until the reflection height ho- rizon is reached, and that useful range coverage will lie between these limits. 
 They internally generate or amplify electromagnetic energy, which is then radiated. Passive  electronic countermeasures do not generate or amplify electromagnetic radiation. They act in  a passive manner to change the energy reflected back to the radar. 
 635 PERFORMANCE CRITERIA AND CHOICE OFSYSTEM CONSTANTS. 638 16.5 Stability Requirements. 638 16.6 Internal Clutter Fluctuations . 
 The receiver serves to (1) separate the desired signal from the ever-present noise and other interfering sig- nals and (2) amplify the signal sufficiently to actuate a display, such as a cathode- ray tube, or to allow automatic processing by some form of digital device. At mi- crowave frequencies, the noise at the receiver output is usually that generated by the receiver itself rather than external noise which enters via the antenna. The input stage of the receiver must not introduce excessive noise which would in- terfere with the signal to be detected. 
 In terms of the bistatic triangle, the required receive beam-pointing angle is73PULSEATt1 RECEIVE BEAM ATt1 PRFAND BEAM SYNCHRONIZATION . , / L cos 0-r \ 0,? = O7- - 2 tan'1 ) (25.25) R ! [RT + RR - L sin 0rj v ' The minimum receive beamwidth (A0^)m required to capture all returns from a range cell intersecting the common beam area is approximated by73 (A0*),,7 - (CTM tan (p/2) + M7R7)IRR (25.26) where TM is the uncompressed pulse width. The approximation assumes that re- spective rays from the transmit and receive beams are parallel. 
 The filter matching loss is less than 0.6 dB and typical time  ch08.indd   30 12/20/07   12:50:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 
 Hence each pulse travels adistance 2vT less than the preceding pulse. This is 2vT/h wavelengths, sothat thephase change is2r2vT/h between each pulse and thenext. The beat frequency isthen 2v/k, asbefore.. 
 WAVE SIGNAL TO THE OUTPUT TRANSDUCER 4HIS GRATING COUPLING DOES NOT HAVE A  SIGNIFICANT IMPACT ON THE SURFACE 
 Tlii~s this  sirnple two-elenlent array with a single 3-dB coupler produces two irldepericle~lt bea111s.  The two-element array is a trivial exarriple of the Butler beam-forming antenna. Figure  8.28 illustrates the circuit of a11 eight-clcrner~t array t1i:it generates eight incleperldent beams. 
 The Collaborative, Adaptive Sensing of the  Atmosphere (CASA) radar network will include many inexpensive, low power, scan - ning, short wavelength radars mounted on towers of opportunity, primarily cell phone  towers that blanket much of the U.S.153,154 Existing equipment on these towers will  FIGURE   19. 9 Vector wind fields in a horizontal  plane derived from dual-doppler radar observations of a  summertime convective storm near Denver, Colorado.  The dark, solid line is shown to indicate the length of a  typical jet aircraft runway. 
 Adifferent sequence isobtained withdifferent feedback connections. (The number ofstagesconnected modulo twomustbeevensinceanoddnumber ofmodulo-two additions takenfromtheall-ones statewillproduce aoneforthenexttermandthecontinued generation oftheall-ones state.Thisgenerates asequence oflength2"- 2andisnotan m-sequence.57)Table11.3liststhenur:nber ofpossible m-sequences obtainable froman II-stageshiftregister. Figure11.20Seven-bit shift-register forgenerating apseudo- Output random linearrecursive sequence oflength127.. 
 FT 
 Figure 1shows geometric relationship between antennas and the target, where antenna TR2 is located at origin O’. Antennae TR1and TR2form the vertical baseline along axis Z’. Deﬁne two coordinate systems, where T’(x’,y’,z’ ) is the radar coordinate system, axis y’is the line of sight of radar, x’ and y’ represent the horizontal and vertical directions, respectively. 
 1970.  30. Collins. 
 The similarity in performance requirements is still evident in the latest revisions of  the IMO performance standard. For instance, the 1946 proposed performance speci - fication included the need to give a clear indication of coastlines rising to 200 ft at  20 miles, of a 500 gross registered ton (“Imperial” units) vessel at 7 miles and of a  30 ft fishing vessel at 3 miles. The modern performance requirements, summarized in  Table 22.1, still use these figures but with parameters, except ranges, given in equiva - lent metric units. 
 More usu - ally, radar frequencies might be from about 5 MHz to over 95 GHz. This is a very large  extent of frequencies, so it should be expected that radar technology, capabilities, and  applications will vary considerably depending on the frequency range at which a  radar operates. Radars at a particular frequency band usually have different capabili - ties and characteristics than radars in other frequency bands. 
 Two phase-sensitive detectors extract the angle-error information, one for azimuth,  the other for elevation. Range information is extracted from the output of the sum channel  after amplitude detection.  Since a phase comparison is made between the output of the sum channel and each of the  difference channels, it is important that the phase shifts introduced by each of the channels be  almost identical. 
 LIKE AMBIGUITY FUNCTION  5SED  THEREFORE  FOR LOW 
 Horn emitter, for the creation of these four i n- dividual directivity patterns with a reflector antenna.  With phase controlled antennas the four  patterns can be realized by four different, however, simultaneous allocations.  Figure 13.2  shows a feeder system for a two -channel monopulse Radar consisting of eight log -periodic  monopole arrays. 
 Besides the imaging resolution, the peak power loss, peak to sidelobe ratio (PSLR) and integrated sidelobe ratio (ISLR) are considered to evaluate the imaging performance. T able 2. Radar System and Orbit Parameters. 
 1403–1413. 172. J. 
 160. L. Sevgi, Complex Electromagnetic Problems and Numerical Simulation Approaches,   Hoboken, NJ: IEEE Press, 2003. 
 The beams all lie in one plane. The system may be combined with mechanical rotation of the antenna, giving vertical switched scanning for 3D coverage. Much greater complexity is required for a system switching beams in both planes. 
 The rms value of the signal-level deviation  ch02.indd   73 12/20/07   1:46:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 The array element spacings decrease with increasing distance from the vertex of the right angle between the arrays. Thus only a positive slope of delay versus frequency can be produced. The bandwidth of the device is dictated by the array designs, and the delay is controlled by the size of the device. 
 A very readable .i  description of the history of radar development at TRE (Telecommunications Research Establish-  ment, England) and how TRE went about its business from 1935 to the end of World War 11.  11. Watson-Watt, Sir Robert: "Three Steps to Victory," Odhams Press, Ltd., London, 1957; "The Pulse of  Radar," The Dial Press, Inc., New York, 1959. 
 COUNTERMEASURES v  -IL  4ECHNOL    PP n  -AY   * ! !DAM AND - ! &ISCHETTI  h3TAR 7ARS 3$) 4HE GRAND EXPERIMENT v  )%%% 3PECTRUM    VOL   NO   PP n  3EPTEMBER   3 * 2OOME  h$IGITAL RADIO FREQUENCY MEMORY v  %LECTRONIC  #OMMUNICATION %NGINEERING  *OURNAL  PP n  !UGUST   * 7 'OODMAN AND - 3ILVESTRI  h3OME EFFECTS OF &OURIER $OMAIN 0HASE 1UANTIZATION v  )"- *  2ES $EVELOP  PP n  3EPTEMBER    - 'RECO  & 'INI  AND ! &ARINA  h#OMBINED EFFECT OF PHASE AND 2'0/ DELAY QUANTIZATION ON  JAMMING SIGNAL SPECTRUM v  0ROC OF )%%% )NT #ONF ON 2ADAR  2ADAR   7ASHINGTON  $#  53!   -AY n    PP n  3 $ "ERGER  h$IGITAL RADIO FREQUENCY MEMORY LINEAR GATE STEALER SPECTRUM v  )%%% 4RANS    VOL !%3n  NO   PP n  !PRIL . Ó{°Èä  2!$!2 (!.$"//+   ' 6 -ORRIS ET AL  h0RINCIPLES OF ELECTRONIC COUNTER 
 TRACING  SUCH AS THE CODE DESCRIBED BY *ONES AND 3TEPHENSON   WHICH CAN PROVIDE PATHS IN THREE DIMENSIONS   INCLUDING DELAYS AND LOSSES FOR BOTH ORDINARY AND EXTRAORDINARY RAYS SEE 3ECTION   !RGUING THAT SUCH COMPREHENSIVE CALCULATIONS ARE EXCESSIVE WHEN THERE ARE SIGNIFICANT UNCERTAINTIES IN THE ELECTRON DENSITY DISTRIBUTION  .2, -EMORANDUM 2EPORT   DESCRIBES THE BASIC TECHNIQUE USED FOR PATH DETERMINATIONS ! SIMPLE  CLOSED 
 Rubin and S. K. Kamen, Ref. 
 For example, in a fully developed sea, the larger waves will tend to move in the direction of the wind while the smaller waves will be more isotropic. Direc- tional spectra are more difficult to measure and are obtained by a variety of ex- perimental methods, such as an array of wave staffs to measure surface heights over a matrix of points, a multiaxis accelerometer buoy, and stereo photography, . and even by processing radar backscatter signals. 
 Sometimes one or two  additional fill pulses are added to the CPI in order to suppress range-ambiguous clutter  returns, as might occur during periods of anomalous propagation. The returns received  during one CPI are processed in the bank of N-pulse finite-impulse-response (FIR)   filters. Then the radar may change its PRF and/or RF frequency and transmit another  CPI of N pulses. 
 DEPENDENT ELEMENT OF THE FILTER WEIGHTING  AND HYPOTHESIS OF THE TARGET STEERING VECTOR )N GENERAL  AUXILIARY DATA TAKEN FROM RANGE BINS OTHER THAN THE CELL UNDER TEST IS USED TO ESTIMATE THE UNKNOWN  BUT CRITICAL  CLUTTER COVARIANCE MATRIX 7ITH COMPENSATION FOR NONSTA 
 Thus U.=coo+m.o, and wehave a carrier uoand anumber ofevenly spaced sidebands, asshown dia- grammatically inFig. 5.3, which shows aspectral distribution resulting from asequence ofpulses. Ofcourse the signal isnot strictly periodio unless tiochances tobeanintegral multiple ofco,. 
 34 INTRODUCTION TO RADAR SYSTEMS  Circumference /wovelength = 2 ~ra/ A  Figure 2.9 Radar cross section of the sphere. a = radius; 1 = wavelength.  interest to the radar engineer because the cross sections of raindrops and other meteorological  particles fall within this region at the usual radar frequencies. 
 Domville, A. R.: The Bistatic Reflection from Land and Sea of X-Band Radio Waves, pt. II, GEC (Electronics) Ltd., Memo SLM 2116, Stanmore, England, July 1968. 
 Smith, P. L., Jr., K. R. 
 PERATURE OR A NOISE FIGURE  IS ONE OF THE FUNDAMENTAL LIMITATIONS ON THE RADAR RANGE 4HE NOISE TEMPERATURE OR NOISE FIGURE OF THE RADAR RECEIVER HAS BEEN REDUCED  TO THE POINT THAT IT NO LONGER REPRESENTS A DOMINANT INFLUENCE IN CHOOSING BETWEEN AVAILABLE ALTERNATIVES )T IS A PARADOX THAT A NOISE PARAMETER IS USUALLY THE FIRST CHAR 
 By letting TI -, 0 in Eq. (11.21), the time-delay error for a triangular-shaped pulse is  obtained. Calling the width at the base of the triangle r, = 2Tz, the rms error is  8~~ =+ triangular pulse 12(2E/No)1'2  Consider a pulse described by the gaussian function  406INTRODUCTION TORADAR SYSTEMS a. 
 Figure 3.14 Unwanted signals in FM  ~apelli,'~ IRE Trans.)  Transmitter leakage. The sensitivity of FM-CW radar is limited by the noise accompanying  the transmitter signal which leaks into the receiver. Although advances have been made in  reducing the AM and FM noise generated by high-power CW transmitters, the noise is irsirally  of sufficient magnitude compared with the echo signal to require some means of minimizing  the leakage that finds its way into the receiver. 
 of Agriculture.  ..} . CHAPTER  FOURTEEN  OTHER RADAR TOPICS  14.l SYNTHETIC APERTURE RADAR 1 3  A synthetic aperture radar (SAR) achieves high resolution in the cross-range dimension by  taking advantage of the motion of the vehicle carrying the radar to synthesize the elTect or a  large antenna aperture. 
 (ed.): Special Issue on Active and Adaptive Antennas,/£££ Trans., vot. AP-12. no. 
 The instruments can provide a servo voltage to hold the two sources at the same frequency and in quadrature at the phase detector. If the sources are such that neither is readily voltage-tunable, then one source is chosen at a typical IF frequency away from the other, and an IF oscillator is locked, in the mean, to the difference frequency. This technique was originally employed in military test equipment designed to measure noise on radars in the field.15'16 The instruments provide a wide range of internal frequencies through a combination of synthesizer techniques at the lower frequencies and combs going up to 18 GHz. 
 At the proper time, the switch is closed and the stored energy is quickly  discharged through the load, or RF tube, to form the pulse. During the discharge part of the  cycle, the charging impedance prevents energy from the storage element from being dissipated  in the source.  Line-type modulator. 
 (From Hansen.51) tive to refractive inhomogeneities in the atmospheric boundary layer. Over dis- tances approaching and beyond the conventional optical horizon, such perturba- tions could produce strong focus-defocus variations along the illumination profile60 or a general rise in the local grazing angle.38 Figure 13.18 gives an ex- perimental example of the effect of ducting on very low angle sea clutter.42 Since the grazing angle given as the abscissa is actually a plot of inverse range, the lift- ing of the cross section by ducting over an order-of-magnitude span of ranges is very likely due to a rise in the mean grazing angle produced by refraction in the evaporative layer.38 Such effects should be suspected whenever the radar prop- agation path extends beyond the optical horizon. GRAZING ANGLE (degrees) FIG. 
 63  A complex target may be considered as comprising a large number of independent objects  that scatter energy in all directions. The energy scattered in the direction of the radar is of  prime interest. The relative phases and amplitudes of the echo signals from the individual  scattering objects as measured at the radar receiver determine the total cross section. 
 Grønlie, “Wave height measurements with a standard navigation ship radar,  results from field trials,” presented at Sixth International Conference on Remote Sensing for  Marine and Coastal Environments, Charleston, South Carolina, 2000. ch22.indd   34 12/17/07   3:02:41 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 K. Moore  37 © IEEE 1984 ) ch15.indd   14 12/15/07   6:17:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The main disadvantage of the diode phase shifter is that an additional  set of diodes is normally required for each additional bit. As lower-sidelobe antennas  are required, the number of bits increases. For low sidelobe antennas, 5, 6, or 7 bits  may be required. 
 The constituent  variables that appear in the equation have been discussed in Sections 20.4–20.11,  emphasizing the unique considerations that arise with HF skywave radar, so the tools  for performance modeling and analysis are available. By considering the case of  noise-limited detection, as applies especially to aircraft targets, the additional com - plications of clutter-limited detection are avoided. In the following paragraphs, two  different approaches to performance modeling for the case of noise-limited detection  are described in some detail. 
 To increase the power output, transistors may be operated in parallel. From 2 to 8 devices  arc ilsually cornhitied into a sitigle power rtrodrtl~. Too large a number cannot be profitably  par-allcled because of losscs tliat occitr on combining. 
 TER RANGE 
 The coupled signals add vectorially to produce a wave traveling toward the generator of element OO that appears to be a reflection from the radi- ator of element 00. As the phases of the neighboring elements are varied to scan the beam, the vector sum of the coupled signals changes and causes an apparent change in the impedance of element 00. For some scan angles the coupled volt- ages tend to add in phase, causing a large reflection and possibly the loss of the main beam. 
 TRACKING ERRORS IN MULTILATERATION TRACKING SYSTEMS THAT TRIANGULATE USING HIGH 
 When the melted mass reached about 10 to 20 percent, the attenuation was about twice that of a completely melted particle. These calcula- tions show that the attenuation in the melting of ice immediately under the O0C isotherm can be substantially larger than in the snow region just above and, underTABLE 23.2 Drop-Size Distribution* Drop di- ameter D, cm 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.700.25 1.25Precipitation rate p, mm/h 2.5 12.5 25 50 100 150 Percentage of a given volume containing drops of diameter D 28.0 50.1 18.2 3.0 0.710.9 37.1 31.3 13.5 4.9 1.5 0.6 0.27.3 27.8 32.8 19.0 7.9 3.3 1.1 0.6 0.22.6 11.5 24.5 25.4 17.3 10.1 4.3 2.3 1.2 0.6 0.21.7 7.6 18.4 23.9 19.9 12.8 8.2 3.5 2.1 1.1 0.5 0.21.2 5.4 12.5 19.9 20.9 15.6 10.9 6.7 3.3 1.8 1.1 0.5 0.21.0 4.6 8.8 13.9 17.1 18.4 15.0 9.0 5.8 3.0 1.7 1.0 0.71.0 4.1 7.6 11.7 13.9 17.7 16.1 11.9 7.7 3.6 2.2 1.2 1.0 0.3 *From Burrows and Attwood.27 TABLE 23.3 Attenuation in Decibels per Kilometer for Different Rates of Rain Precipi- tation at Temperature 180C* Precipi- tation rate p, mm/h 0.25 1.25 2.5 12.5 25.0 50 100 150X = 0.3 0.305 1.15 1.98 6.72 11.3 19.2 33.3 46.0X = 0.4 0.230 0.929 1.66 6.04 10.4 17.9 31.1 43.7X = 0.5 0.160 0.720 1.34 5.36 9.49 16.6 29.0 40.5Wavelength X, cm X = 0.6 0.106 0.549 1.08 4.72 8.59 15.3 27.0 37.9X = 1.0 0.037 0.228 0.492 2.73 5.47 10.7 20.0 28.8X = 1.25 0.0215 0.136 0.298 1.77 3.72 7.67 15.3 22.8X = 3.0 0.00224 0.0161 0.0388 0.285 0.656 1.46 3.24 4.97X = 3.2 0.0019 0.0117 0.0317 0.238 0.555 1.26 2.80 4.39X = 10 0.0000997 0.000416 0.000785 0.00364 0.00728 0.0149 0.0311 0.0481 . *From Burrows and Attwood.27 some circumstances, greater than in the rain below the melting level. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 3.8 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 was 3% of the PRF. 
 Delano and I. Pfeffer, “The effects of AGC on radar tracking noise,” Proc. IRE , vol. 
 To compensate for the inherent droop in gain of the TWT output section at the edges of the band, the klystron cavities were purposely tuned to boost the gain at those frequencies. Because it is part klystron and part TWT, Varian named the hybrid tube a Twystron.33 A 3 dB bandwidth of 14 per- cent has been demonstrated in the VA-145, or a 1 dB bandwidth of 12 percent; 48 percent efficiency has been shown at midband with 41 dB gain. Although more complex and expensive than most klystrons, the Twystron appears capable of equally high power with broader bandwidth than all but perhaps the clustered- cavity klystron. 
 Normally it would be expected that the decorrelation time would be  linearly proportio~lal to the frequency, since the doppler-frequency shift is also linearly related  to tlie frcqucltcy. ).lowever, experimental measurements show that the ratio of the decorrela-  tion tir~lc at L band to that at X band is less than would be expected if the linear relation  applietl. For exarnplc, if the decorrelation time at X band were 10 ms, then it would be about  60 tns at L band, instead of the 70 to 75 ms predicted on the basis of a linear law. 
 Signal modulation isapplied tothecontrol grid, and the second setofdeflecting plates receives a~-oltage that produces the azi- muthal deflection. This may befurnished, insimple cases, byalinear potentiometer geared tothescan axis. simplification may sometimes be necessary before applying theazimuth sweep voltage tothecathode-ray tube. 
 TION SYSTEMS ERODE MORE AND MORE PORTIONS OF THE SPECTRUM AT TH E EXPENSE OF MILITARY  %##- CAPABILITY  Ó{°nÊ , 
 14.12 arrives at the  receiver via two separate paths, one being the direct path from transmitter to receiver, the  other being the scattcr!'d path which includes the target. The measurements which can be  made at the bistatic receiver arc:  t. The total path length ([), + D,). 
 LIMITED SIT UATIONS IS A VITAL PART  OF THE RADAR DESIGNERS TASK  REQUIRING A DETAILED UNDERSTANDING OF THE PHENOMENA AND THEIR DISTRIBUTIONS Óä°ÎÊ  /",-Ê  1 
 The instrument weighs 68 kg (150 Ib) and occupies a volume of 0.119 m3 (4.2 ft3) including the antenna, which is a 0.6-m (24-in) diameter parabolic dish withAntenna Type Beamwidth Look angle Gain Polarization Weight Transmitter Type Efficiency RF carrier Peak power Pulse length PRF Duty cycle Average power Waveform Receiver Noise temperature Bandwidth System input noise AGC time constant STC gain variation Stalo stability Recorder System weight Total prime power Resolution Swath width Swath length Swath orientation Signal-to-noise ratioPlanar phased array (10.74 m x 2.16 m) 1.1° azimuth, 6° elevation (1 dB points) 20° depression, 90° with respect to the velocity vector 34.7 dB Horizontal 113kg Solid-state transistor 38 percent 1275 MHz 800 W (nominal), 1125 W (maximum) 33.8 |is 1463, 1540, 1645 pps 0.05 (maximum) 44.5 W (nominal), 62.6 W (maximum) Pulse, LFM, 19-MHz Bandwidth 55OK 22MHz - 127.42 dBW 5s 9dB 3 x 10~10in5ms 25 kb/s digital 110 kg (excluding antenna) 624 W (maximum) 25m 100km 2000 km per pass Right side of orbit path 9 dB (nominal)TABLE 22.3 Synthetic Aperture Radar . a 2.6° beamwidth and a 36 dB gain. The instrument is packaged in two basic sections: an RF section and an attached electronics section, which are both mounted to a center-cylindrical disk baseplate with a diameter of 0.65 m (26 in). 
 The quality parameters of the strong scattering target imaging result. Parameters Imaging on Reference Plane Imaging by Proposed Method Coordinates (m,deg) (220.91,185.19) (220.91,185.19) Height (m) 36.82 36.82 Range direction resolution (m) 1.00 1.00 Range direction PSLR (dB) −13.21 −13.22 Azimuth direction resolution (m) 1.92 1.91 Azimuth direction PSLR (dB) −8.63 −12.57 7. Conclusions In this paper, an interferometric DEM-assisted high precision imaging method for ArcSAR is proposed. 
 TION  AND ALSO A WIDER IMAGED AREA THAN A PURE 3POT3!2 CAN SUPPORT.   30!#% 
 These correspond to frequencies in the Rayleigh and the  low-resonance regions. The use of such frequencies is said to provide overall dimensions,  approximate shape, and material composition. Instead of the impulse response, the response of  a target to a ramp function is sometimes more convenient to work with, especially when the  longer wavelengths are used to obtain target classification. 
 TO 
 ERY  USUALLY VISUALIZED AS A BLACK 
 6.14. The charging impedance is  shown as an inductance. The pulse-forming network is usually a lumped-constant delay line. 
 SOID  CAN BE USED TO OBTAIN  6H  THE HORIZONTAL WIND SPEED  THE WIND DIRECTION WHERE COS  A IS MAXIMUM  AND  6F  THE MEAN PARTICLE FALL SPEED ALL PLOTTED AS A FUNCTION OF HEIGHT  4HIS TECHNIQUE IS REFERRED TO AS THE 6ELOCITY 
 4HE DIFFERENT TYPES OF %##- ARE RELATED TO THE PROPER USE AND CONTROL OF THE POWER  FREQUENCY  AND WAVEFORM OF THE RADIATED SIGNAL /NE BRUTE 
 13.2. Cathode-ray Tube Screens. Phosphorescent Screens.—The important characteristics ofthe screen areitsdecay properties, itseffi- ciency, and themanner inwhich itintegrates or“builds up” onrepeated signals. 
  D"   N    
 These have also been called linear recursive sequences (LRS), pseudonoise (PN)  sequences, and binary-shift-register sequences. Although the sequence is a series of zeros or  ones, for application to the phase-coded pulse-compression radar the zeros can be considered  as corresponding to zero phase and the ones to n radians phase.  Since an m-sequence takes on all possible states except the zero state, the initial state of  the shift register does not affect the content of the sequence, but will define the starting point of  the sequence. 
 A high rotation rate is needed for good target track-  ing. A low rotation rate is desired for more hits on target, which reduces tlie requiremcnts for  large transmitter power or antenna aperture. For a surveil!ance radar the product of average  power, antetitla aperture. 
 Conical scan or sequential lobing, to sense target direction, depend upon measuring the  amplitude of the signal for at least two different antenna beam positions for each tracking  axis. In azimuth tracking, for example, the antenna beam is displaced to the left of the  target and then to the right. If the target were on the antenna axis, the signal would drop  the same amount when the beam (assumed to be symmetrical) is moved an equal amount  in either direction. 
 475-492, March, 1933.  6. U.S. 
 12. Inthemanufacture ofcrystals tomeet thespecifications (which area considerable advance over those met bythecrystals used inearly micro- wave radars) careful attention must begiven totheoriginal purity ofthe silicon, to“doping” with small amounts ofthe proper impurity, tothe preparation ofthecrystal face, and tothesharpening and adjustment of the whisker. Crystals arestored inmetal containers toavoid burnout from stray r-ffields. 
 Some radar manufacturers provide a SART search mode that sets the  radar optimally for their detection, including inhibiting pulse-to-pulse correlation  and optimizing filter bandwidths. AIS-based SARTs have now been proposed. These  may eventually replace radar-based SARTs because the latter are difficult to detect  in adverse conditions. 
 CIRCLE GROUND DISTANCE 4HE APPARENT RANGE TO A PARTICULAR TARGET MAY TAKE ON MORE THAN ONE VALUE SINCE MULTIPLE PATHS MAY EXIST 7ITH THESE INTERPRETATIONS  THE RADAR EQUATION %Q   CAN BE USED TO MODEL  THE PERFORMANCE OF SKYWAVE RADARS WHEN NOISE  NOT CLUTTER  IS SETTING THE LIMIT TO  TARGET DETECTABILITY  NOTING THAT THE COMPLEXITY AND STATISTICAL NATURE OF IONOSPHERIC PROPAGATION AND THE EXTERNAL NOISE ENVIRONMENT MEANS THAT IT IS OFTEN NECESSARY TO APPLY THE EQUATION TO PROBABILITY DISTRIBUTIONS  NOT SCALAR  VALUES OF THE PARAM 
 TAPERED ANECHOIC  CHAMBER v )%%% 4RANS  VOL !0 
 ........................  14  Transmitters Power  ................................ ................................ 
 The Randell  and Boot magnetron operated at a wavelength of 10 cm and produced a power output of  about 1 kW, an improvement by a factor of 100 over anything previously achieved at cen-  timeter wavelengths. The development of the magnetron was one of tile most important  contributions to the realization of microwave radar.  The success of microwave radar was by no means certain at the end of 1940. 
 J. F. Ramsay, J. 
 In addition  to allowing the received signal to be separated from the transmitted signal, tho CW radar  provides a measurement of relative velocity which may be used to distinguish moving targets  from stationary objects or clutter.  3.2 CW RADAR  Consider the simple CW radar as illustrated by the block diagram of Fig. 3.2~~. 
 to.2 that the output of the matched  filter is the autocorrelation of the input signal for which it is matched, if noise>can be neg­ lected.) The binary phase-coded sequence of 0, n values that result in equal sidelobes after  passage through the matched filter is called a Barker code. An example is shown in Fig. l l. 
 In statistical terms it is  claimed to be a uniformly most powerful test and is an optimum one, no matter what the a  priori probabilities of signal and noise. 25 The Neyman-Pearson criterion is wen suited for  radar application and is usually used in practice, whether knowingly or not. DETECTION OF RADAR SIUNALS IN NOISE 377  Likelihood-ratio receinr. 
 TRICAL REQUIREMENTS ON THE PACKAGING  OF --)# COMPONENTS INTO A  42 MODULE IS FUN 
 SEC 
 It is worth noting that pulsar Crab emissions observed by Arecibo radio telescope are preliminary and coherently de-dispersed. In Figure 1a typical main pulse with three microbursts, registered between 2 and 10 GHz with 125 ns time resolution and 8 MHz frequency spectrum resolution using the Goldstone-Apple Valley radio telescope is presented. The bar at the top right illustrates the generalized, over all frequency channels, root mean square (RMS) power level in the time-frequency coordinates. 
 The concept of noise temperature of a radiating source is based on Planck's law or on the Rayleigh-Jeans approxima- tion to it, analogous to the relationship of resistor noise temperature to Nyquist's theorem. FIG. 2.8 Block diagram of a cascade receiving system.SOURCE(ANTENNA) T0PASSIVETRANSDUCER(TRANS. 
 BAND LOW 
 MITTER DEDICATED  COOPERATIVE  OR NONCOOPERATIVE   GIVEN AN ADEQUATE ,/3 BETWEEN TRANSMITTER AND RECEIVER )N THE INDIRECT METHOD  PRESYNCHRONIZED STABLE CLOCKS ARE USED BY THE RECEIVER AND A DEDICATED TRANSMITTER 4HE RECEIVER MEASURES THE TIME INTER 
 NOISE JAMMING ARE CONSIDERED AND THE SYSTEM REQUIREMENTS ARE DERIVED TO DETERMINE THE FEASIBILITY AND PRACTICALITY OF SUCH JAMMER 2ESULTS OF A COMPUTER SIMULATION OF AN ENGAGEMENT BETWEEN 3!2 AND REPRESENTATIVE JAMMING SYSTEM ARE GIVEN TO ENABLE THE EFFECTIVE 
 W. Crispin, Jr. et al., “A theoretical method for the calculation of radar cross section of aircraft  and missies,” University of Michigan, Radiation Lab. 
 121. G. F. 
 BASED 3!2 CAPABILITY 3INCE THE LAUNCH OF THE FIRST  %UROPEAN 2ADAR 3ATELLITE %23 
 Figure 14.6 shows the basic arrange­ ment of an optical processor. The film contains the superposition of the holographic signals  from all the individual scatterers illuminated by the radar. It is sometimes called the phase  l1istory or siqnal history. 
 FADING CASE AFTER 6 ' (ANSEN Ú )%%%  . 
 [ CrossRef ] 31. West, J.; Ventura, D.; Warnick, S. Spring Research Presentation: A Theoretical Foundation for Inductive T ransfer ; Brigham Young University, College of Physical and Mathematical Sciences: Provo, UT, USA, 2007. 
 West 114  © The American Geophysical Union 2003 )Meters Time(s) (a) (b)Arbitary Units0 0 0.1 0.2 0.3 0.4 0.5 0.6(Curvature)2SlopeRadar SurfaceRelative height or echo amplitude0.8 0.6 0.4 0.21.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 ch15.indd   35 12/15/07   6:17:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter. 
 TION CELL TO THE NEXT ! TYPICAL DISTRIBUTION OF  R   TAKEN FROM "ARTON  IS SHOWN IN  &IGURE  4YPICAL VALUES FOR  R  AND G  FROM THE SAME REFERENCE ARE GIVEN IN 4ABLE   !DDITIONAL RESULTS FOR CLUTTER REFLECTIVITY ARE FOUND IN "ILLINGSLEY 4!",%  4YPICAL 6ALUES OF #LUTTER 2EFLECTIVITY #LUTTER2EFLECTIVITY  K  M G  M n#ONDITIONS"AND  K  M#LUTTER 0ARAMETERS FOR  4YPICAL #ONDITIONS ,  3  #  8   ,AND EXCLUDING    POINT CLUTTER  SL  WORST  PERCENT         R  D"  n n n n 0OINT CLUTTER R    M       R  M   3EA "EAUFORT SCALE   + "  ANGLE % R  D"    
 Otherwise, the   FIGURE 25.23  Direct Digital Synthesizer (DDS)NCO DACANALOG SIGNAL ch25.indd   20 12/20/07   1:40:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 
 SUITED TO BEING EXPLOITED BY MATRIX DECOMPOSITION METHODOLOGY   &OR A GIVEN TRANSMITTED POLARIZATION  THE VALUES OF THESE 3TOKES PARAMETERS ARE  INVARIANT WITH RESPECT TO THE POLARIZATION BASIS OF THE RECEIVER )T FOLLOWS THAT THE OPTI 
 Also in an HF radar, the elevation beamwidth Or is often not  available as a design parameter because of the large cost of high antenna structures. Substituting  into Eq. ( 14.22) G, = G, = G = n2/000r, where 00 = azimuth beam width; and T.: = ts00/0r, ts=  revisit time (scan time) and Or = total azimuth angle coverage, we get  (" R4 _ ._. 
 This can be important in harbor, river, island, and estuary  regions, where shielding by the terrain or buildings can affect radar range. A shipborne AIS station broadcasts information divided into a number of sets.  These comprise static data, such as the ship’s name, type, length, and beam; dynamic  data, including position, SOG, COG, and heading; and voyage-related data, such as  destination port and ETA, depth under keel, and hazardous cargo type. 
  INSTRUMENTS )T IS A STAND 
 WAVE %CHOES  7HEN THE ANGLE OF INCIDENCE IS A SMALL GRAZING ANGLE OFF  THE SURFACE  A SURFACE TRAVELING WAVE CAN BE INDUCED 4HE SURFACE WAVE TENDS TO BUILD UP TOWARD THE REAR OF THE BODY AND IS USUALLY REFLECTED BACK TOWARD THE FRONT BY ANY DISCONTINUITY AT THE REAR 4RAVELING 
 BASED RADAR INSTRUMENTATION COMPLEX AS THE SHIP STEAMED IN A LARGE CIRCLE ON #HESAPEAKE "AY 4HE THREE TRACES IN THESE CHARTS ARE THE     AND  PERCENTILE LEVELS OF THE SIGNALS COLLECTED OVER ASPECT ANGLE hWIN 
 LINE OR A LOADED 
 FORM DIGITAL &)2 FILTER 4HE INPUT SAMPLE FEEDS A SHIFT REGISTER  WHERE EACH BLOCK LABELED  S   INDICATES A ONE 
 TION BY PRECIPITATION AND ATMOSPHERIC GASSES !T  CM WAVELENGTHS THE ATTENUATION IS USUALLY NOT SIGNIFICANT HOWEVER  AT     AND  CM AND ESPECIALLY THE YET SHORTER MM WAVELENGTHS  ATMOSPHERIC ATTENUATION MUST BE ACCOUNTED FOR IN THE RADAR EQUATION BY ADDING AN ADDITIONAL RANGE DEPENDENT TERM  , A 4HE FOLLOWING SECTION GIVES DETAILS ON  ESTIMATING THIS ATTENUATION IN COMMONLY ENCOUNTERED CONDITIONS &INALLY  IT IS IMPORTANT TO NOTE THE  : VALUES ARE OF METEOROLOGICAL SIGNIFICANCE  BECAUSE THEY ARE DIRECTLY RELATED TO CLOUD PROPERTIES AND ACTUAL RAINFALL RATES  2 AS  DESCRIBED LATER IN THIS CHAPTER  : VALUES IN NONPRECIPITATING CLOUDS AS SMALL AS   n D": ARE OF INTEREST FOR CLOUD PHYSICS STUDIES )N THE OPTICALLY CLEAR  LOWER ATMO 
 CAL A   B C   D   SPURIOUS COMPONENTS AT  
 SHAPED BEAMS POINTED TO  n AND n TO EITHER SIDE OF THE ORBIT  PLANE )NCIDENCE SPANNED  n TO n  COVERING A  
 Ê"ÊÊ *1 - 
 Bur. Stand. Monog. 
 Random errors include (1) errors in the machining or manufacture of the antenna as  a consequence of the finite precision of construction techniques, (2) RF measurement errors  incurred in adjusting an array, (3) wall-spacing errbrs in metal-plate lenses, (4) random distor-  tion of the antenna surface, and (5) mechanical or electrical phase variations caused by  temperature or wind gradients across the antenna. Although random errors may be relatively  small, their effect on the sidelobe radiation can be large. Systematic errors are usually the same  from antenna to antenna in any particular design constructed by similar techniques. 
 If care is taken in the construction of the model and in the pattern-range  instrumentation, it is possible to achieve reasonably representative measurements.  The radar cross section of an aircraft can also be obtained by computation.1 7 The target is  broken up into a number of simple geometrical shapes, the contribution of each (taking . 40 INTRODUCTION TO RADAR SYSTEMS  35 dB  Figure 2.16 Experimental cross section of the B-26 two-engine bomber at 10-cm wavelength as a function  of azimuth angle. 
 For citation purposes, cite each article independently as indicated on the article page online and as indicated below: LastName, A.A.; LastName, B.B.; LastName, C.C. Article Title. Journal Name Year ,Article Number , Page Range. 
 Because of theinterference pattern, the target must rise somewhat above the radar horizon. Size Up to certain limits, targets having larger reﬂecting areas will return stronger echoes than targets having smaller reﬂecting areas. Should a targetbe wider than the horizontal beam width, the strength of the echoes will notbe increased on account of the greater width of the target because the areanot exposed to the radar beam at any instant cannot, of course, reﬂect anecho.Sincetheverticaldimensionsofmosttargetsaresmallcomparedtotheverticalbeamwidthofmarinenavigationalradars,thebeamwidthlimitationis not normally applicable to the vertical dimensions. 
 42. Meuehe, C. E.: Digital Signal Processor for Air Traffic Control Radars, IEEE NEREM 74 Record,  Part 4: Radar Systems and Compotrents, pp. 
 44. C. A. 
 AIDED AND SKIN 
 58. Graf, W., R. N. 
 http://en.wikipedia.org/wiki/Space-Based_Radar 11. http://www.astronautix.com/craft/priroda.htm 12. http://www2.jpl.nasa.gov/srtm/ 13. 
 Now the marker scale could be changed to the more accurate 30 miles scale, by selecting the 30/30 position. The range marker would now change position but could be moved by the operator back to the previously identi ﬁed target position. Similarly, the scale could be moved in two steps through 30/10 to the 10/10 range scale. 
 Introduction The Synthetic Aperture Radar (SAR) [ 1–4] can acquire very-high-resolution images of the inspected area using high bandwidth of the transmitted coherent illumination signal by means of an accurate processing of the ground-received returns. In a standard structure, the system is composed of a platform (i.e., airborne or satellite) using the same antenna both for the transmitting and receiving phases; the target scene is repeatedly illuminated with pulses of radio waves. The signal echoes are emitted at equispaced positions along the satellite track, and their returns are received in the band of the transmitted pulse, converted, and IQ-sampled to produce the baseband complex raw data. 
 One 200-M c/sec beacon was used fortwo-way voice communication while still functioning foritsnormal use. For themost part, however, this usefor communications has been somewhat incidental. Much fuller use ofthe channels could bemade since the portion ofthe spectrum required for transmission ofbeacon signals ofasimple sort isample forconveying much more complicated intelligence. 
 L.. arid G. E. 
 13. Mie, G.: Beitrage zur Optik triiber Medien, speziell kolloidaler Metallosungen [Contri- bution to the optics of suspended media, specifically colloidal metal suspensions], Ann. Phys., vol. 
 63. Andrews, G. A.: Airborne Radar Motion Compensation Techniques, Evaluation of DPCA, NRL  Report 7426, Naval Research Laboratory, Washington, D.C., July 20, 1972. 
 One such web-based application is the Navy’s  Composable ForceNet, an application similar in nature to the GCCS-M. Figure 26.11  is an illustration of the Composable ForceNet application. For this illustration, the  background for the Composable ForceNet COP is a hypothetical ocean and island  operation area. 
 63. D. Trizna, “A model for doppler peak spectral shift for low grazing angle sea scatter,” IEEE   J. 
 JAMMED IMAGE BY ADAP 
  
  ORBITERS MAPPED  STRIPS OF THE SURFACE OF 6ENUS  RANG 
 FREQUENCY ALTIMETERS WITH NO 762  FURNISHED THE BEST RESOLUTION OCEANIC GEODESY AND BATHY METRY AVAILABLE UP  THROUGH AT LEAST  FOR THE OPEN OCEAN 4HEIR RESULTING BATHYMETRIC RESOLUTION IS LIM 
 Remote Sens. Environ. 2013 ,129, 132–143. 
   RADIO NOISE MODEL 4HE PROBABLE CAUSE v 2ADIO 3CIENCE  VOL   PP n    " * .ORTHEY AND 0 3 7HITHAM  h! COMPARISON OF $34/ AND $%2! (& BACKGROUND .OISE  MEASURING SYSTEMS WITH THE )NTERNATIONAL 2ADIO #ONSULTATIVE #OMMITTEE ##)2  MODEL DATA v  $34/ 4ECHNICAL 2EPORT $34/ 
 13.8) shows that, all other factors remaining constant, the shorter the pulse  width the greater will be the maximum' range. Decreasing the pulse width decreases the  amount of clutter with which the target must compete. There are three cautions to remember,  however, when considering the use of Eq. 
 LIKE SPECTRUM OF &- TRANSMISSIONS 4HE MODULATION CONTENT OF MANY BROADCAST TRANSMITTERS CHANGES AS A FUNCTION OF  TIME  THEREBY COMPLICATING MATCHED FILTERING BY THE 0"2S RECEIVER 3PECIFICALLY  THE RECEIVER MUST SAMPLE AND STORE A SEGMENT OF THE DIRECT PATH WAVEFORM AND THEN CROSS 
 $ SYSTEMS PROVIDE QUANTITATIVE AND AUTOMATED REAL 
 TARGET TRACK  MULTIPLE TARGETS CAN BE TRACKED SIMULTANEOUSLY OVER A LARGE VOLUME OF SPACE ! SECOND METHOD OF -ULTIPLE 
 L,( P) Psn(v)  Pn(v) ( 10.21)  It is a measure of how likely it is thal the receiver envelope vis due to signal-plus-noise as  compared with noise alone. It is a random variable and depends upon the receiver input. If the  likelihood ratio L,(11) is surficicntly large, it would be reasonable to conclude that the signal  was indeed present. 
 CALLY BY THE FOLLOWING SIMPLIFIED ONE 
 Frequency multiplication is frequently used in gen - erating local oscillator CW frequencies where all frequencies are typically based on a  ch06.indd   49 12/17/07   2:04:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 1.2 and Chap. 2) shows that the range of a radar is proportional to the fourth root of the transmitter power. Thus, to double the range requires that the power be increased by 16. 
 #AVITY +LYSTRONS  4HIS IS A GOOD EXAMPLE OF THE TECHNIQUE OF GROUPING  CAVITIES TO IMPROVE THE OPERATION OF A KLYSTRON 4HE INDIVIDUAL INTERMEDIATE CAVITIES OF  A MULTICAVITY KLYSTRON ARE EACH REPLACED BY A CLUSTER OF TWO OR THREE ARTIFICIALLY LOADED LOW 
 8.2 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 increasing the waveform pulsewidth without exceeding constraints on transmitter peak  power. The average power of the radar may be increased without increasing the pulse  repetition frequency (PRF) and, hence, decreasing the radar’s unambiguous range. In  addition, the radar is less vulnerable to interfering signals that differ from the coded  transmitted signal. 
 BEAM CLUTTER RETURN WILL BE ZERO OR $# #LUTTER 2ETURN 'ENERAL %QUATIONS  4HE CLUTTER 
 PERMANENT 
 BOUNCEv PROCESSES INVOLVING "RAGG SCATTER FROM FIRST ONE AND THEN ANOTHER WAVE TRAIN   WITH THE TWICE 
 Any radome extending beyond the fuselage line ofthe airplane should therefore bestreamlined. The drag foraprotuberance ofgiven shape increases inapproximate proportion toitsfrontal area. Itistherefore desirable toreduce the projected area ofthe radome asmuch aspossible even tothe extent of having the radome surface coincide with the skin oftheplane. 
 K. Hawkins, C. E. 
 The aspect entropy after denoising is closer to the result of simulation and it has a greater ability of discrimination and clustering. The aspect entropy of targets of the same type is concentrated in a limited range. The aspect entropy of vehicles is in the range [0.5567, 0.6418]. 
 Tlii~s ttle  sea in the North Atlantic is not that muchdifferent from the sea in the South Pacific if the wind  conditions are the same. Land clutter, on the other Iiand, is lligllly ~L'I)L'I~CICII~ i)ri (tic IlitItl1.C 01'  the terrain and the local conditions. Urban areas, cultivated fields, forests, mountains, desert,  and tundra all can produce different radar echoes. 
 It is sometimes called the whitening filter. The second is the matched filter described  by Eq. ( 10.15) when the input is white noise and a signal whose spectrum is S(/)/ Ni(/). 
 creating spurious targets on tlie radar display at directions other than that of the  true targct  A r.trrrccc~-qrto src~c~lt~r is a repeater jammer whose function is to cause a tracking radar to  " hrca k lock " or1 t lie target. It will be recalled from Sec. 5.6 that a tracking radar can track a  targct it1 range by generating a pair of range gates within tlie radar receiver and adjusting these  gates to center on tlic target. 
 Vingst, D. R. Carter, J. 
 BEAM CLUTTER IS POSITIONED AT ZERO DOPPLER FRE 
 (ILL    % "ROOKNER AND 2 * "ONNEAU  h3PECTRA OF ROUNDED TRAPEZOIDAL PULSES HAVING AN !-0-  MODULATION AND ITS APPLICATION TO OUT 
 This compels G3  to follow G2 in potential change as regards instantaneous  potential changes.  Two separate cases are met with:  (a) If the drop in the potential in G2 which would be  caused (in the absence of C) by the drop in the potential  of G3 is less than the drop in potential of G3, the circuit  will return to its original condition when the original  ‘cause’ is removed. This is the stable state. 
 Thus ifweconsider the earth asadiffuse reflector }\-e easily find thereceived power is(1/2m) (A/r2) times theearth’s reflection coefficient and times the transmitted power. Even for very small transmitter powers and reflection coefficients, this power islarge compared tothermal noise. Onthe basis ofexperience, then, itwas decided that the0.3watt available from anacorn tube would besufficient foraltitudes upto5000 ft,provided certain points ofapparatus detail were correct, asexplained below. 
 Asimilar American set(AY/TPS-10) islighter and simpler since it operates at3cm. This enables theantenna size tobereduced to10by 3ftwith thevery high gain of18,000. The range isover 50miles ona four-motored aircraft, although the radar setuses only 60-kw output power atl-~sec pulse width and 1000 pps. 
 BASED ELECTROMAGNETIC TECHNIQUE  DESIGNED PRIMARILY FOR THE LOCATION OF OBJECTS OR INTERFACES BURIED BENEATH THE %ARTHS  SURFACE OR LOCATED WITHIN A VISUALLY  OPAQUE STRUCTURE '02 IS A SUCCESSFUL EXAMPLE OF  THE EXPLOITATION OF ULTRAWIDEBAND RADAR AND TYPICALLY A '02 WITH A RANGE OF  M WOULD OPERATE OVER THE RANGE  '(Z TO  '(Z !LTHOUGH '02 HAS MANY SIMILARITIES TO RADAR SYSTEMS  THERE ARE SOME KEY DIFFER 
 WEST SLOPE COMPONENTS 4HESE RESULTS REFLECT THE LESS 
 RANGE INSTRUMENTATION )N BOTH APPLICATIONS  A HIGH DEG REE OF PRECISION AND AN  ACCURATE PREDICTION OF FUTURE POSITION OF THE TARGET ARE GENERALLY REQUIRED 4HE EARLIEST USE OF TRACKING RADAR WAS GUNFIRE CONTROL 4HE AZIMUTH ANGLE  ELEVATION ANGLE  AND THE RANGE TO THE TARGET WERE MEASURED  AND FROM THE RATE OF CHANGE OF THESE PARAMETERS  THE  VELOCITY VECTOR OF THE TARGET SPEED AND DIRECTION  WAS COMPUTED AND ITS FUTURE POSITION  PREDICTED 4HIS INFORMATION WAS USED TO MOVE THE GUN TO LEAD THE TARGET AND SET THE FUZE DELAY 4HE TRACKING RADAR PERFORMS A SIMILAR ROLE IN PROVIDING GUIDANCE INFORMATION AND STEERING COMMANDS FOR MISSILE CONTROL )N MISSILE 
 Thetworegionsof interestinradarpropagation aretheillte/.'(e/.'ellce regionandthedit/i'actiol/ region.Theinter­ ference.oroptical.regionislocatedwithinlineofsightoftheradar.Thedirectandrdkcled wavesinterfere toproduce alobedradiation patternsimilartoIhatdescribed fortheplane Free-spacecoverage contour 90°30°50,000T I45,000\ I .;:40'OOO-t 0"35,000 cc '"c30000 -- 0 '">0.025,000. 0 1: 0> V.c.20,000 Qj 0>aI-10° Range,nmi (a)horizontal polarization Figure12.4Exampleoravertical-plane coverage diagramfor(a)horizontal polarization and(b)vertical polarization. Frequency=1300MHz,antennaheight=50ft,antennaverticalbeamwidth =12°with heammaximum pointing onthehorizon, seasurfacewith4flwave-height andafreespace range=100nmi. 
 T able 3. D1, D2, and D3 dataset. D1 Dataset D2 Dataset D3 Dataset Label T rain V alidation Label T rain V alidation Label T rain V alidation Bulk Carrier 896 304 Bulk Carrier 6110 4560 Bulk Carrier 5595 4255 Container Ship 272 128 Container Ship 4080 1920 Container Ship 4114 1936 Oil Tanker 272 128 Oil Tanker 4080 1920 Oil Tanker 4114 1936 T able 4. 
 number )lots pertrack 5.4 5.6 5.9 7,8 6.3 6.6.4vg. number ,lotsperheight 8,7 8.7 5.0 10.4 9,0 5.4 The FDP “C” was equipped with one ofthe preproduction 10-cm radar sets designed forlong-range airwarning and control (see Chap. 15). 
 17.9  Ground Clutter in a Mo ving Radar  ......................  17.9  Clutter Return: General Equations  .....................  17.10 Sidelobe Clutter   ................................................. 
 Inthedevelopment ofradar, the beacons came asanafterthought. The result was that. SEC.83] GENERAL IL)ENTIFICA TIt)N SYSTEMS, IFF 251 beacon performance often was not sogood ascan beobtained. 
 It represents, by far, the largest use of radar.  THENATURE OFRADAR13 lines.andotherships,aswellasforobserving aircraft. Airborne radarmaybeusedtodetect otheraircraft, ships,orlandvehicles, oritmaybeusedformapping ofland,stormavoidance, terrainavoidance, andnavigation. 
 Result after image fusion. 4.2. Measured Data In order to validate the effectiveness of the proposed algorithm, the large-angle spotlight SAR measured data are processed using the proposed algorithm. 
 R. Vaughn, “Birds and insects as radar targets: A review,” Proc. IEEE , vol. 
 ARRAY    ARCHITECTURE  SHOULD BE SUCH THAT  4(4   ) )N THIS WAY  THE NOISE POWER AT SUB 
 inwhichatargetisindicated bythedeflection oftheelectron beam.Theotheristhe illtensit,l'-modtllated CRT,suchasthePPI,inwhichatargetisindicated byintensifying theelectron beamandpresenting aluminous spotonthefaceoftheCRT.Ingeneral, deflection-modulated displays havetheadvantage ofsimplercircuitsthanthoseofintensity­ modulated displays, andtargetsmaybemorereadilydiscerned inthepresence ofnoiseor interference. Ontheotherhand,intensity-modulated displays havethe'advantage ofpresent­ ingdatainaconvenient andeasilyinterpreted form.Thedeflection ofthebeamorthe appearance ofanintensity-modulated spotonaradardisplaycausedbythepresence ofa targetiscommonly referred toasablip. Thefocusing anddeflection oftheelectron beammaybeaccomplished electrostatically, electromagnetically, orbyacombination ofthetwo.Electrostatic deflection CRTsusean electricfieldappliedtopairsofdeflecting electrodes, orplates,todeflecttheelectron beam. 
 In a  pllascd array, tllc bcam is scanned by electronically varying the phase of the currents across  the aperture.  1.4 RADAR FREQUENCIES  Conventional radars generally have been operated at frequencies extending from about  220 MHz to 35 GHz, a spread of more than seven octaves. These are not necessarily the limits,  . 
 Wurman, J. Straka, E. Rasmussen, M. 
 REFLECTED  RAYS FROM REACHING THE TARGET FROM THE RADAR  AND VICE VERSA  B Y SHIELDING THE SPECULAR  ZONE ON THE GROUND FROM BOTH 4HE NEAR SIDES OF THE FENCES SHOULD BE SLANTED TO DEFLECT ENERGY UPWARD OUT OF THE TARGET TEST ZONE  AND MAY BE COVERED  WITH ABSORBING MATE 
 Sweeney, L. E.: Spatial Properties of Ionospheric Radio Propagation as Determined with Half-Degree Azimuthal Resolution, Stanford Electron. Lab. 
 Hansen, R. C.: Workshop on Conformal Arrays, Microwa,,e J., vol. 18, p. 
 48. D. Lynch, “SLOSH filter processing,” presented at IEEE AU Symposium on Digital Filters,  Harriman, NY , January 1970. 
 22.5 SBR at 5600-nmi orbital altitude and the sun angle progression.3212 NOON 12 MIDNIGHTSOLAR FLUX TITANIUM GRAPHITECOMPOSITE NOON MIDNIGHT NOONRMSDEVIATION (in) ORBITTIME (LOCATIONS) FIG. 22.4 Thermal distortion.29 CIRCULARORBIT (6h) TO EARTH UPPER STAYGROUND PLANESUNRIMLOWER STAY LOWER DIPOLEPLANE UPPER DIPOLEPLANESUNEARTH ECLIPSE 45 min . DEFLECTION WAVELENGTHS FIG. 
 SIZE REPLICA  OF A MISSILE  TRANSPORTER 
 WIDTH IS NOW  .S   THE NOMINAL COMPRESSED 
 The common tube becomesimpractical for certain functions and must be replaced by tubes of specialdesign. Among these are the klystron andmagnetron. Since it is very difﬁcult to amplify the radio-frequency echoes of the carrier wave, radio-frequency ampliﬁers are not used. 
 When the target-decision process is made by an operator viewing a cathode-ray-tube  display, it would seem that the criterion used by the operator for detection ought to be  arialogous to the setting of a threshold, either consciously or subconsciously. The chief differ-  ence between tlie electronic and the operator thresholds is that the former may be determined  with some logic and can be expected to remain constant with time, while the latter's threshold  might be difficult to predict and may not remain fixed. The individual's performance as part of  the radar detection process depends upon the state of the operator's fatigue and motivation, as  well as training. 
 Zheng, B.; Wei, Y. Improvements of autofocusing techniques for ISAR motion compensation. Acta Electron. 
 TO 
 Receiver design also must be concerned with achieving sufficient gain, phase, and ampli­ tude stability, dynamic range, tuning, ruggedness, and simplicity. Protection must be provided  against overload or saturation, and burnout from nearby interfering tr~nsmitters. Timing and . 
 The logic of  this approach is that the probability of detection is proportional to the average RCS  over a range of solid angles of observation, and if the width of the lobe is narrow  enough, its contribution to the average RCS may be less than if it were a wider but  less intense lobe. The required RCS pattern levels of specific vehicle concepts should  be established by means of mission analyses before deciding which shaping criterion  is applicable. Shaping is usually difficult to exploit or expensive to implement for vehicles or  objects already in production because the vehicle configuration and profile have been  selected and optimized for specific mission objectives. 
 MATIONS CREATED BY A LARGE IMPACT  COULD GENERATE FALSE WATER 
 FIELD RANGES TO PERFORM FACTORY  CALIBRATION ARE 4(!!$ AND 3!-03/.  .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°È£ &OR AN ACTIVE ARRAY  BOTH THE PHASE AND AMPLITUDE OF EACH ELEMENT MUST BE MEASURED  IN ORDER TO DETERMINE THE CORRECTION CONSTANTS FOR EACH ARRAY ELEMENT IN BOTH TRANSMIT  AND RECEIVE MODE &ULL CALIBRATION OF AN ACTIVE ARRAY IS MEASUREMENT INTENSIVE )T IS COM 
 loss(number greaterthanunity)andefficiency (number lessthanunity) areusedinterchangeably. Oneissimplythereciprocal oftheother. Plumbing loss.Thereisalwayssomefinitelossexperienced inthetransmission lineswhich cOllnect theoutputofthetransmitter totheantenna. 
 Antenna height = 2 x aper- ture height; lower beam boresighted at H0 = 0.5; upper beam boresighted at H, = 1.5; reflection coefficient = — 1. (d) Squinted-sum low-angle sensitivity factor. Antenna height = 2 x aperture height;U = L/X SIN O -NORMALIZED SINE-SPACE ANGLE (U-SPACE) (c)U = L/X SIN O *•NORMALIZED SINE-SPACE ANGLE (U-SPACE) (d)U = L/X SIN d *•NORMALIZED SINE-SPACE ANGLE (U-SPACE) (a)U = L/XSIN 6 *•NORMALIZED SINE-SPACE ANGLE (U-SPACE) (b) IN CLEARIN MULTIPATHIN CLEARWITH MULTIPATH . 
 The SAW device must provide a response that is centered on a carrier, as the lowest frequency of op- eration is about 20 MHz and is limited by the crystal. A matched-filter SAW pulse compression device can use variable finger lengths to achieve frequency weighting, and this internal weighting can correct for the Fresnel wiggles11 in the FM spectrum. With this correction, 43 dB time-sidelobe levels can be achievedINPUT INPUT INPUT OUTPUTDISPERSIVE TRANSDUCER MATCHING SIGNAL (a) (b)OUTPUT OUTPUT . 
 N FI~. 325-Mouth oftheSusquehanna Rilcr atHavrc deGIWC, lfd. Bll]l(iings of Edgewood Arsenal and.\ herdeen Pro\,ing Grour]d alevibible asbright patcllesst]~]tt1 ofthe electrified railway line. 
 STATE DEVICES BY CHANGING THE DRAIN VOLTAGE PULSE DURATION  WHILE HOLDING THE 2& PULSE CONSTANT ! SECOND 
 Figures 11and 12show that the reconstructed target information of traditional approach has a larger deviation. Regardless of complete data or insufﬁcient data provided, the target can be imaged effectively. What’s more, with the decrease of data quantity, the imaging performance gets worse. 
 For new radar systems, the system designers have been motivated by these considerations to choose as high a duty cycle as possible, both to reduce the peak power required and to permit using solid-state devices at a reasonable cost. With a 10 percent duty cycle, for example, the 500-W average power men- tioned earlier in the paragraph could be provided by only 25 to 50 of the 50-W transistors. The decision to use a high transmitter duty cycle, however, has significant im- pact on the rest of the radar system. 
 Inthesetests,the bestresultswereobtained whentheplaneofpolarization wasswitched insmallincrements (5.6to22.5°)atarategreaterthan500stepspersecond, whichismorethananorderof magnitude greaterthanthe40Hzconical-scan rate. ~-angle tracking.41-53,90- 94Aradarthattracksatargetatalowelevation angle,nearthe surfaceoftheearth,canreceivetwoechosignalsfromthetarget,Fig.5.15.Onesignalis reflected directlyfromthetarget,andtheotherarrivesviatheearth'ssurface. (Thisissimilarto thedescription ofsurfacereflections anditseffectontheelevation coverage, asinSec.12.2.) Thedirectandthesurface-reflected signalscombine attheradarto.J'.k1d-an anglemeasure­ mentthatdiffersfromthetruemeasurement thatwouldhavebeenmadewithasingletargetin theabsence ofsurfacereflections. 
 31, pp. 135–143, April 1988.  99. 
 KM SQUARE IMAGE FRAME  DUAL 
 LOOKING RADAR v * !TMOS /CEAN 4ECHNOL   VOL   PP n    , ,IANG AND 2 -ENEGHINI  h! STUDY OF AIRSPACE 
 For higher power levels, other kinds of slow- wave circuits with a higher RF velocity must be used, and the bandpass characteristics of those circuits can lead to band-edge oscillation problems. Furthermore, both forward waves and backward waves may propagate on the RF structures, leading to the possibility of backward-wave oscillations. Depending on the circuit used, other kinds of oscillations can also occur. 
 That part of the wave structure directly produced  by these winds is called sea. But waves propagate, so even in the absence of local  wind, there can be significant local wave motion due to waves arriving from far away,  perhaps from a distant storm. Waves of this type are called swell , and since the surface  over which the waves travel acts as a low-pass filter, swell  components often take the  form of long-crested low-frequency sinusoids. 
 NAS  FOR INSTANCE  CAN THEN BE BASED ON FREQUENCY RESPONSE OVER THE ANTICIPATED BAND OF INTEREST AND SUITABILITY FOR THE CHOSEN ARRAY GEOMETRY  AS WELL AS TERRAIN CONSTRAINTS SUCH AS THE SOIL CONDUCTIVITY 3TUDIES HAVE SHOWN THAT THIS ARGUMENT IS NOT NECES 
 Water-wave directions neither will be confined to the wind direction nor will they be semi-isotropic, but they will spread throughout 360°, with the spreading function depending upon frequency and other variables. Oceanographers generally treat the directional wave spec- trum in the wind direction half plane only.22 But HF radar has sufficient sensi- tivity to expose the waves running against the wind that have an RCS more than two orders of magnitude below those running with the wind. If the wave directional-spectrum distribution of Long and Trizna is used, the maximum value . 
 In phase-coded waveforms, the pulse is subdivided  into a number of subpulses each of duration d  = T/N where T is the pulsewidth and N  is the number of subpulses. Phase-coded waveforms are characterized by the phase  modulation applied to each subpulse.  Binary Phase Codes. 
 BOARD ACTIVE PHASED ARRAY MULTIFUNCTION RADAR )T IS AN 8 
 ING WAS ASSUMED TO INVOLVE MULTIPLE 02& INTERVALS BASED ON CLASSICAL LOW 02& RADARS USING A SINGLE -4) FILTER )T WAS FOR THIS REASON THAT THE -4) )MPROVEMENT &ACTOR DEFI 
 Wahl, D.E. Phase gradient autofocus—A robust tool for high resolution SAR phase correction. IEEE T rans. 
 4.8). Hard limiting also introduces an additional loss. The larger the  ratio of the bandwidths M, the less the loss. 
 TOR v )%%% 4RANS  VOL !%3 
 BASED 3!2 ARE THE SAME AS THOSE APPLICABLE TO AIRBORNE SYSTEMS  ALTHOUGH THEY PLAY OUT RATHER DIFFERENTLY 4HE FUNDAMENTAL REQUIREMENT IS THAT THE 02&  F P   BE SUFFICIENTLY HIGH TO SAMPLE UNAMBIGUOUSLY THE DOPPLER SPECTRUM OF WIDTH  "$OP   AND ALSO SUFFICIENTLY LOW SO THAT THERE IS TIME BETWEEN TRANSMISSIONS TO RECEIVE  THE DATA BACKSCATTERED FROM THE INTENDED SWATH OF SLANT RANGE TIME 
 News, pp. 119-136, October 1984. 55. 
 14.4. Motor-alternator Sets.—Table 143 gives common sizes of motor-alternator sets now inuse. T.mL~ 14,3.—~w@Io~ SIZM OF~lOTOW.ILTEhN.tTOI? S~Ts Capacity, va — 100 250 500 750 840” (1OOO) 1500 2500Frequency of output, Cps 400 400 400 400 800 400 400Phases 3 lor3 1 10r3 1 1 1l}-eight, lb 13 23 38 32t 5-.0 ’7519.2””” 21.8 19.8 262(31.5) 27.2 33,4 *840isnamqlat. 
 As depicted in Figure 11.1, this design  attribute helps to extend the solid-state performance envelope well into the region that  had previously been dominated by only vacuum electronics.1,2 It is not the intent of this  chapter to delineate the relative merits of these sometimes competing technologies,  but rather to describe the limits, design practices, and characteristics of the solid-state  technology for use in the common radar frequency ranges. The advantages of solid- state technologies will be described; some of the key semiconductor technologies and  devices will be discussed; and some examples of solid-state component and transmitter  design will be presented. 11.2 ADVANTAGES OF SOLID STATE Although the gap in performance capabilities between the solid-state and vacuum  electronics technologies can be wide, there still exist relevant trades involving cost,  maintainability, and reliability, and this design tradespace can be very complicated. 
 DEFINED CRITERION L $ETAILED DESCRIPTION OF THE SELECTED APPROACH   4HIS IS IN TERMS OF THE CHARACTERISTICS OF THE RADAR AND THE TYPE OF SUBSYSTEMS TO   BE EMPLOYED L !NALYSIS AND EVALUATION OF THE PROPOSED DESIGN   4HIS IS TO VERIFY THE CORRECTNESS OF THE SELECTED APPROACH !S ONE PROCEEDS THROUGH THIS PROCESS   ONE MIGHT REACH A hDEAD ENDv AND HAVE TO  START OVERSOMETIMES MORE THAN ONCE (AVING TO START OVER IS NOT UNUSUAL DURING A NEW DESIGN EFFORT /NE CANNOT DEVISE A UNIQUE SET OF GUIDELINES FOR PERFORMING THE DESIGN OF A RADAR  )F THAT WERE POSSIBLE  RADAR DESIGN COULD BE DONE ENTIRELY BY COMPUTER "ECAUSE OF THE USUAL LACK OF COMPLETE INFORMATION  MOST ENGINEERING DESIGN REQUIRES  AT SOME POINT  THE JUDGMENT AND EXPERIENCE OF THE DESIGN ENGINEER IN ORDER TO SUCCEED 4HE 2ADAR %QUATION IN #ONCEPTUAL $ESIGN  4HE RADAR EQUATION IS THE BASIS  FOR CONCEPTUAL RADAR SYSTEM DESIGN 3OME PARAMETERS OF THE RADAR EQUATION ARE DETER 
 1.3, the use ofacommon antenna for transmitting and receiving requires fast-acting switchesl todisconnect the receiving apparatus from the antenna during the transmitted tron pulse, and todisconnect the mag- netron during the period when echoes are being received. These two switches are called the TR (transmit-receive) switch and the anti-TR orATR switch, respec-W lhQ.11.14 .—Duplexing system ontw~wire tively. The duplexer isthat por- transmission line. 
 VIDES ONLY PARTIAL REDUCTION IN THE TRANSIENT SETTLING TIME )F FEEDFORWARD ONLY IS USED   ONLY THREE OR FOUR PULSES HAVE TO BE GATED OUT AFTER MOVING THE BEAM 4HE DISADVAN 
 The most cornrnoii is the rigid space-frame, Fig. 7.29, which consists of a three-  dimensional lattice of primary load-bearing members enclosed with thin dielectric panels. The  panels can be very thin, even for large-diameter radomes, since they are not required to carry  main loads or stresses. 
 However, antennas used for radar have an added severe demand to minimize mechanical motion that would cause signal modulation, and this requirement is easier to meet with low-antenna-height designs. Among the many factors that influence antenna design are: 1. The transmitter-receiver antenna gain product must be large enough to make its required contribution to sensitivity. 
 Galati, G.: Range-tracking in Tracking Radars: Analysis and Evaluation of the Accuracy, Rit:isru  Technica Selenia (Rome, Italy), vol. 2, no. 2, pp. 
 When thetwo signals areequal, the bisector ofthe angle between the two positions ofthe beam ispointed directly atthetarget. The signals from agiven target may becompared forthe two positions ofthe beam bypresenting them side-by-side onatype Kindicator or 1ByE.C.Pollard, L.N.Ridenour, andD.C.Soper.. 188 THEGATHERING ANDPRESENTATION OFRADAR DATA [SEC. 
 modulation requirements, and the method ofcooling. A transmitter is a  niajor part of a radar system; hence, its size, cost, reliability, and maintainability can  significantly affect the size, cost, reliability, ar~d maintainability of the radar system of which it  is a part. Not only does the transmitter represent a significant fraction of the initial cost of a  radar systetn, but it cat1 often take a large share of the operating costs because of the prime  power and the rieeds of maintenance. 
 coupling loop isintegral with the mixer. The crystal ismounted asa part ofthecenter conductor ofashort coaxial line and makes amatched termination with nospecial transformers. Since the i-fsignal must be extracted, theend ofther-fline cannot bead-cshort circuit. 
 I.  Skolnik (ed.), McGraw-Hill Book Co., New York, 1970.  48. 
 Thus  the threshold varies continuously according ''J the noise ur the clutter environment fo~md  within a range interval surrounding the range cell under observation. 76 This form of CF AR  has sometimes been called Adaptive Video Threshold, or A VT. The particular CF AR shown in  Fig. 
 SOLID-STATE TRANSMITTERS  11.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 ● Flexibility can be realized. A module with both transmit and receive path amplifiers  (T/R module) can be associated with every antenna element in phased array sys - tems. RF distribution losses that normally occur in a tube-powered system between  a point-source tube amplifier and the face of the array are thus eliminated. 
 Siegel:" Methods of Radar Cross-Section Analysis," Academic Press,  New York, 1968.  18. Rowman, J. 
 Clutter harmonic distortion, noise foldover, and (for the case of the illuminator) approach-recede ambiguity are eliminated. However, feedthrough rejection now requires a complex notch filter at the relatively high offset frequency rather than a simple high-pass filter. Also, clutter still controls the gain normalization in the doppler amplifier. 
 One of the most distinctive differences is around the eddy cores, where the NRCS of the simulated eddy should be darker. We believe that this is due to the incapability of the M4S model to take a three-dimensional current ﬁeld as input. The altitude change caused by the eddy will generate a vertical velocity component, and it gets larger near the eddy core. 
 ING CAN BE APPLIED AT THE OUTPUT SIGNALS OF EACH SUB 
 /",Ê 
 (Copyright 1968 IEEE.4} ka = 2?ra/X FIG. 11.5 RCS of a slender dielectric cylinder with er = 3.0.10 log (a/Tra2) . ANGLE FIG. 
 A,. ;~ritl K. W. 
 TO 
 With this display we do not see the comb pattern  clearly, because a screen is chosen which has a fairly  considerable afterglow, leaving a greenish-grey (or blue-  grey) faint square of light. On this background sudden  spots of light appear as the tracing-spot at that very  instant is strobed, indicating an echo. This display does  not show height, of course, but if you regard the picture  on the tube as a distorted sort of map of what is seen  ahead of the aircraft you will realize that at once, without  any mathematical interpretation, the pilot can see the  azimuth of his object, and its approximate range. 
 Care must betaken that surrounding fixed objects donot introduce alack ofrotational symmetry and that nomagnetizable material isincluded intherotating parts. Multiple coils are used for many different purposes. Their fields must occupy thesame axial region ofthetube inorder toavoid serious defocusing and distortion which otherwise take place when deflections 1) (g),,, l’1<; .13:3.-Deflertion ancl focwiug dr~ices for m:lgn?tir Cl{T. 
 476–481, February 1958. 69. J. 
 Crossed-Field Amplifiers (CFAs). High efficiency, small size, and relatively low-voltage operation make CFAs especially attractive for lightweight systems for transportable or airborne use, from UHF to K band. Having relatively low gain, CFAs are generally used only in the one or two highest-power stages of an amplifier chain, where they may offer an advantage in efficiency, operating voltage, size, and/or weight compared with linear-beam tubes. 
 °È  2!$!2 (!.$"//+  4HE THREE 
 450 INTRODUCTION TO RADAR SYSTEMS  Equations (12.11) have been used at times as a measure of the line-of-sight coverage of a  ground-based radar viewing a target at a height h. This may lead to incorrect results in some  cases since the optical line of sight does not necessarily correspond to the radar line of sight, as  explained in Sec. 12.6. 
 IRE, vol. 44, pp.  801-810, June, 1956. 
 Both kinds of detectors test whether the test cell has a return sufficiently larger than the reference cells. Clutter maps allow variation in space, but the clutter must be stationary over several (typically 5 to 10) scans. Clutter maps store an average background level for each range- azimuth cell. 
 ( 10.26) shows that the most probable  waveform si(t) is the one which has the least-mean-square deviation from the received  waveform y(t).  The computation of the a posteriori probability might be accomplished by computing the  cross-correlation function between the actual waveform and the various possible waveforms  that might be received. Expanding the integral in Eq. 
 17.9]COMPARISON OFSYNCHRONIZATION METHODS 711 The tracking circuits are similar tothe circuit shown inFig. 17.13c except forchanges made toprovide forascanconverter and forthefact that the switching voltages forthesawtooth delay circuits areprovided bythe same flip-flops that control the sine- and cosine-pulse switches. A-c signals forthescan converter areobtained bymodulating the60-cps line voltage with the sine and cosine voltages, asinFig. 
 Using the beam approach beacon system (BABS), only one antenna was used on the aircraft. The BABS transponder on the ground had a split beam and transmitted alternately on each beam. The two beams transmitted ﬁxed length pulses (possibly about 5 μs) but with one beam transmitting for a period of 0.2 s and the other for 1.2 s, known as dot and dash signals, respectively [ 4]. 
 4  There are other factors beside the noise figure which can influence the selection of a  receiver front-end. Cost, burnout, and dynamic range must also be considered. The selection of  a particular type of receiver front-end might also be influenced by its instantaneous band-  width, tuning range, phase and amplitude stability, and any special requirements for cool~ng. 
 The  better MTI performance results from the better match between the clutter filter characteristic  and the clutter spectrum. ·  4.5 OIGITAL SIGNAL PROCESSING  The introduction of practical and economical digital processing to MTI radar allowed a  significant increase in the options open to the signal processing designer. The convenience of  digital processing mcaus Iha\ multiple .~t!lay-li11~ canc~l-~rs_with ta_iloreJL[rco~1:1cncy-response  characteristics can he readily achieved. 
 (1)wemust $’: therefore relate thedifferent anwith— —.+ various known quantities. Aprecise, l,. f+ and complete connection forallpos-f. 
 5.4a in time so as to  cover the entire pulse-repetition period (Fig. 5.4b). This is possible only in a range-gatt:d  receiver. 
 G. Elford., “The meteor response function: theory and application to nar - row beam MST radar,” Planet. Space Sci. 
  
 Fuzzy Clustering With a Modiﬁed MRF Energy Function for Change Detection in Synthetic Aperture Radar Images. IEEE T rans. Fuzzy Syst. 
 Hutchison, P. T.: The Image Method of Beam Shaping, IRE Trans., vol. AP-4, pp. 
 Arelatively fast-acting average- current device issuitable forthis purpose. The electrostatic capacity ofthe load should nearly always bekept toaminimum, Not only isthe energy spent incharging this capacity. SEC. 
 .. 6 1.4 The Performance ofRadar. 8 1.5 Radar Systems .,..., . 
 244 INTRODUCTION TO RADAR SYSTEMS  Twist reflector  (90° polarization-rotation  mirror)  ·,.  ta .;1c  Rado me  Figure 7.14 Configuration of the mirror-scan antenna for obtaining 360° scanning without RF rotating  joints. (From B. 
 Donaldson, Jr., “Severe 5-cm radar attenuation of the Wichita  Falls storm by intervening precipitation,” in 19th Conf. Radar Meteorol. , AMS, Boston, 1980,   pp. 
      
 Higherfrequencies absorbed atorclosetothesurfaceofthe60dyaremore likelytobeperceived thaninterior heating. Therehavebeenfewauthenticated incidents whereradiations havebeenthecauseof biological damage inhumans. However, asradarpowersincrease, thelikelihood ofbiological damage becomes greater,andifseriousharmistobeavoided, propersafetyprecautions must beobserved. 
 CALLED ELECTRONIC COUNTER 
   
 Persistence of vision will thus give the effect of two  echo blips side by side, one of which will usually be  greater than the other. If we know our aerial polar  diagrams comparison of the respective heights will show  us in what area is the effective ‘line of shoot.’ Thus we  can ascertain the angle of elevation with respect to  ground-level, and so know the height of our aircraft.  Although a Split display gives the effect of two echoes  side by side {or in some systems one echo reversed, so  that it hangs beneath), we should never forget that it is  only persistence of vision which makes this picture on  the tube. 
 TION APPLIED  AND FABRICATION ERRORS IN THE 3!7 DEVICE 4IME SIDELOBE LEVELS OF n D" HAVE BEEN ACHIEVED FOR 4" BETWEEN  AND  4" PRODUCTS OF UP TO  HAVE BEEN ACHIEVED  WITH TIME SIDELOBES BETTER THAN n D" $YNAMIC RANGE IS LIMITED BY NON 
 The material in  this chapter is designed to be reasonably complete at a survey level; the discussion  zooms in on selected case examples to illustrate application-specific implementa - tions or technological innovations. An outstanding early example is the Seasat satel - lite launched in 1978 (Figure 18.1), which (as its name suggests) was designed for  oceanic observations. Three of its sensors were SBRs—a synthetic aperture radar, an  altimeter, and a scatterometer. 
 Ince, W. J., and D. H. 
 TIONS 4HE BIPOLAR JUNCTION TRANSISTOR "*4  IS SO NAMED BECAUSE THE CONDUCTION PATH THROUGH THE TRANSISTOR MAKES USE OF BOTH MAJORITY AND MINORITY  CHARGE CARRIERS TO ESTAB 
 PLANE PLOT OF FAR 
 13.4 there are techniques for receiver  detector-design that can avoid much of this loss.) A corollary consequence of high resolution  is a change in the probability dknsity function of the sea echo, as described next.  , '  Probability density function of sea clutter. The amplitude of sea clutter is characterized by  statistical fluctuations which8must4be described.iri terms of the probability density function. 
 The number of zeros  used in the fixed- (zero doppler) clutter-notch section of the MTI is determined by the  required improvement factor and the spectral spread of the land clutter. Typically, the  fixed-notch MTI would use two or three zeros. For the adaptive portion of the MTI,  a fully digital implementation is shown in which the pulse-to-pulse phase shift of the  clutter output from the first canceler is measured and averaged over a given number of  range cells. 
 80, pp. 522-545, 1954. 21. 
 DOWN ! SOLID 
 J. B. Billingsley et al., “Statistical analyses of measured radar ground clutter data,” IEEE Trans. 
 The waveforms  and clutter cancellation requirements are key drivers in the decision whether to per - form STAP on signals before or after doppler filtering. In addition, the overall trans - formation decisions to reduce degrees of freedom are driven by the interference rank  for the radar problem. One caution in the design process is that if the transformation  is fixed in the radar design, it is important to have excess degrees of freedom beyond  the total interference rank. 
 THE MAGIC EYE I4t  sent to, and echoes received from, the rotating H2S  scanner. A rheostat control regulates the speed of  rotation, as the wedge-shaped slice of illumination covers  the terrain, and the trace line, as in all normal PPI  techniques, rotates in step at the same speed. By dis-  playing echo returns the H2S tube trace paints and con-  tinually repaints a map on the tube end. 
 1.M.•andE.R.Graf:Frequency-Agility Processing toReduceRadarGlintPointing Error. IEEETrans.,vol.AES-IO,pp.811-820, November, 1974.. 31. 
 Ithasbeensaid75thatthemaximum increase innoise levelthatcanbetolerated withamanual systemusingdisplays anJoperators isfrom5to 10dB.Butwithanautomatic detection andtracking (ADT)system,thetolerable increase is lessthan1dB.Excessive falsealarmsinanADTsystemcausethecomputer tooverload asit attempts toassociate falsealarmswithestablished tracksortogenerate new,butfalse,tracks. Manual control istooslowandimprecise forautomatic systems. Someautomatic, instanta­ neousmeansisrequired tomaintain aconstant false-alarm rate.Devicesthataccomplish this purpose arecalledCFAR. 
 HAND PICTURE COULD NOT BE DETECTED  NO MATTER HOW LARGE ITS RADAR CROSS SECTION )N THE RIGHT 
 CUSSED IN 3ECTION  /THER APPROXIMATE METHODS NOT DISCUSSED HERE ARE EXPLORED IN DETAIL IN SOME OF THE REFERENCES LISTED AT THE END OF THIS CHAPTER 4HE PRACTICAL ENGINEER CANNOT RELY ENTIRELY ON PREDICTIONS AND COMPUTATIONS  AND  MUST EVENTUALLY MEASURE THE ECHO CHARACTERISTICS OF SOME TARGETS 4HIS MAY BE DONE BY USING FULL 
 R. J. Donaldson, Jr., “V ortex signature recognition by a doppler radar,” J. 
 ING 4HE DATA TO AND FROM THE  MISSILE IS OFTEN AN ENCRYPTED PHASE 
 16 (The burnout conditions for pulses 1 µs or greater is essentially  the same as for CW.) Crystal diodes can withstand several watts or more of peak power under  pulse conditions. For pulses shorter than 1 µs, the peak-power capability increases, but not at  a sufficient rate for constant energy.15  In addition to leakage through the duplexer, diode burnout can result from the accidental  reception of power from nearby radars or from (he discharge of static electricity through the  diode.  Noise figure due to RF losses. 
 Figure 8. I 5 is a plot of the beam direction as a function of the frequency for various  values of the ~·wrap-up fqcto,' t/d, as given by Eq. (8.18). 
 Thelargertheaperture (orthegreaterthenumber ofelements inthearray),the betterwillbetheapproximation. TheFourier seriesmaybeusedtosynthesize thepatternofadiscrete array,justasthe Fourier integral maybeusedtosynthesize thepatternofacontinuous aperture.74Similar conclusions apply.TheFourier-series method isrestricted inpractice toarrayswithelement spacing inthevicinityofahalfwavelength. Closerspacing resultsinsupergrain arrayswhich areno!practical.75.76Spacings largerthanawavelength produce undesired gratinglobes. 
 2.7 as a function of the signal-to-noise ratio with  the probability of a false alarm as a parameter.  Figure 2.6 Probability-density function for noise alone  arid for signal-plus-noise, illustrating the process of  tl~resl~old detection.  (2.28)THERADAR EQUATION 27 probability' ofdetection I'distherefore Pd=.(~{ls{R}dR=(~~~exp( -R2 2:oA2 )10(~:)dR Thiscannotheevaluated bysimplemeans,andnumerical techniques oraseriesapproxima­ tionmustbeuscd.1\sericsapproximation validwhenRANo ~1,A~IR -AI,andtermsin A-3andbeyondcanbeneglected is9 I( VI--A)I'd=I-err,.. 
 DEPENDENT IONOSPHERIC TILTS OR GRADIENTS  )N ADDITION TO MULTIPATH  EACH INTERFERENCE COMPONENT IS SUBJECTED TO TEMPORAL AND SPATIAL DISTORTIONS CAUSED BY THE DYNAMIC BEHAVIOR OF ELECTRON DENSITY IRREGULARITIES PRESENT IN THE INDIVIDUAL REFLECTING LAYERS  4HIS PHYSICAL PHENOMENON  IS KNOWN NOT ONLY TO DEFORM THE INTERFERENCE WAVEFRONTS RELATIVE TO THE ANTICIPATED PLANE WAVEFRONT  BUT ALSO TO INDUCE A SIGNIFICANT LEVEL OF SPATIAL NONSTATIONARITY ON THE VARIOUS INTERFERENCE COMPONENTS OVER TIME INTERVALS COMMENSURAT E WITH THE COHERENT  PROCESSING INTERVAL OF /4( RADARS IN THE ORDER OF A FEW TO TENS OF SECONDS    2ELEVANCE TO )NTERFERING 3IGNALS  3OURCES OF INTERFERENCE WITHIN THE RADAR COVERAGE  EG  ON AN AIRBORNE PLATFORM  CAN POTENTIALLY SCREEN THE PLATFORM IN RANGE AND IMPAIR THE DETECTION OF OTHER TARGETS WITH SIMILAR AZIMUTH BUT POSSIBLY AT DIFFERENT RANGES  . 
 There are two fundamental limits to the maximum effective length of the synthetic aper­ ture. One limit is determined by the width of the region illuminated at the range R by the real  antenna. The length of the effective aperture Le can be no greater than the width of the  illuminated region as given by Eq. 
 Themeasurement ofrangeisthemeasurement of timedelayTR=2R/c,wherecisthevelocity oflight.Onemethodofdetermining rangewitha pulsedwaveform istomeasure thetimeatwhichtheleadingedgeofthepulsecrossessome threshold I(Fig.11.1).Thepulseuncorrupted bynoiseisshownbythesolidcurve.Theshape ofthepulseisnotperfectly rectangular; theriseanddecaytimesarenotzero,forthiswould requireaninfinitebandwidth. Theeffectofnoiseistoperturb theshapeofthepulseandto shiftthetimeofthreshold crossing asshownbythedashedcurve.Themaximum slope(rateof rise)oftheleadingedgeofarectangular pulseofamplitude Aattheoutputofavideofilteris Figure11.1Measurement or timedelayusingtheleading(or trailing)edgeorthepulse.Solid curverepresents echopulseun­ corrupted bynoise.Dashed curverepresents theeffortof noise.__ _-....... 11 "/1 /h/ -- - - \Rectangular pulse \.~"Rectangular"pulse \"plusnoise \ A \Threshold--------\------- \ \ \ ""-..... 
 Therequired distance separation depends upon range. Assuming a 2˚ beamwidth, targets at 10 miles must be separated by over 0.35 nautical miles or700 yards to appear as separate pips on the PPI. At 5 miles the targets mustbe separated by over 350 yards to appear as separate pips if the beam widthis 2˚. 
 To enable tracking, the electrically asymmetrical dipole feed spins at1800 rpm, thus scanning the beam conically; this has the incidental effect of gyrating theplane ofpolarization oftheenergy. Five units, driven bya spring-loaded gear train, are provided forazimuth data transmission: four synchros, ofwhich one isgeared torotate at16-speed, and one potentiometer. Asiscommon practice indata transmission, each take- offmay beindividually adjusted byloosening itsmounting clamps and rotating the stator case for proper angular setting inrelation tothe antenna. 
 TION DISTORTION FROM DEGRADING RADAR PERFORMANCE È°£ÎÊ 76 
 Keeler, R. J., and C. L. 
 Guest editorial and invited papers in special issue on shortwave broadcasting, IEEE  Trans.  Broadcast., vol. 34, June 1988. 
 (a) SSN = 10. (b) SSN = 100.Ground Range (nmi) (a)• = R4th Loss• = R4fh + L 0 = Frequency* = El. Angle ^ 1 deg.» = Noise• = R4th Loss• = R4fh + L 0 = Frequency* = El. 
 Real radars do not produce cookie-cutter footprints, however, since the an- tenna beam will have, say, a Bessel or gaussian profile and the pulse might be shaped. For this reason, an effective A must be obtained from a surface integra- tion of the square of the actual amplitude profile of the footprint, which will al- ways result in a smaller value of A than that defined by Eq. (13.8) or Eq. 
 W.: Bistatic and Multistatic Radar, chap. 36 of" Radar Handbook," M. I. 
 17”2. The third pulse, originating inV2. ofthat figure (repeated inFig. 
 Bogotch, S. E .• and C. E. 
 Any  number of receivers may work off the Gee station with-  out fear of overloading. For civil aviation Gee offers a  very practical advantage in that we know it works  because it has been set up on a considerable scale all  over Europe. You will find most Gee transmitters  working on frequencies around 60 Mcs, but the possible  Gee range is from 20 to 85 Mcs. 
 A major objective for both of these radars is to look for evidence of ice deposits  in the permanently shadowed areas of the Moon’s polar regions. This requires that  they must measure the circular polarization ratio (CPR). Hence, they transmit circular  polarization, and they are dual-polarized on receive. 
 702-703, May 1976. 11. Judd, G. 
 Thenumber islimitedbythequalityoftheswitches, as measured bythedifference between theirimpedance inthe Hoff"and"on"positions. With manyswitches inparallel,the"off"impedance ofeachmustbehighifthecombined im­ pedance istobelargecompared tothe"on"impedance ofasingleswitch.Aparallel-line configuration with16lengthsoflineprovides aphasequantization of22.5°(±11.25°),assum­ ingthe11thlineisoflength1J.A./16.Asuitable formofswitchisthesemiconductor diode.The diodesattached totheendsoftheparticular lineselected areoperated withforward biasto present alowimpedance. Theremaining diodesattached totheunwanted linesareoperated withhack-hias topresent ahighimpedance. 
 Scanning or steering of a pencil-type narrow beam in elevation can be accomplished by means of electronically controlled phase shifters placed at the row feed outputs of an array antenna. This approach is the most flexible of the various 3D radar height finding techniques, allowing full use of the frequency band for purposes beyond beam scanning and allowing for com- . plete independence of waveform and beam position. 
 65. Weil, H., M. L. 
 11.24  11.4 RCS Measurement Techniques  .............................  11.34  General Requirements  .......................................  11.35 Outdoor Test Ranges  ........................................ 
 E., and L. Weinberg: Digital Multiple Beamforming Techniques for Radar, IEEE  EASCON '78 Record, pp. 152-163, Sept. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar.  GROUND PENETRATING RADAR  21.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21  es = low frequency limiting value of the permittivity  w   = radian frequency = 2p  f )  t   = relaxation time constant The frequency of maximum movement and loss occurs at w  = 1/t. 
 SHADOWING FUNCTION )T WOULD  APPEAR THAT A COMBINATION OF CONVENTIONAL SHADOWING WHICH GOES AS THE FIRST POWER OF THE GRAZING ANGLE  ACROSS  THE WIND  AND THRESHOLD SHADOWING  IN UPWIND AND DOWN 
 FREE  ISOTROPIC RECEIVING ANTENNA IS THE  POWER DENSITY OVER THE ENTIRE SPHERES SURFACE TIMES THE AREA OF THE SPHERE COVERED  BY THE RECEIVER ANTENNA  ALSO CALLED THE ANTENNAS EFFECTIVE APERTURE   !E 4HE EFFECTIVE  APERTURE IS RELATED TO THE WAVELENGTH K   OF RADIATION BY   !' E K O     4HUS   THE POWER AT THE RECEIVER   0R   FOR ISOTROPIC RADIATING AND RECEIVING ANTENNAS  'T   'R     IS   00 !0 RRA ET  K O      4HE  FREE 
 9.3 The adaptive array scheme.JAMMER TARGET COMPARISON WITHTHRESHOLD . pulses from each antenna of the array) to the enhancement of the target signal and to the cancellation of clutter, chaff, and jammer. Several generalizations of the basic theory have been considered, including: (1) the target model S is not known a priori, as it is assumed in deriving Eq. 
 The efficiency of an integrator that operates continuously without dumping is  Tlie rnaxin~irnl efficiency of a dumped integrator occurs for = 0, but for a continuous integra-  tor tl~c niaxitnunl cflicicticy occurs for II~ = 1.257.  2.7 RADAR CROSS SECTION OF TARGETS  The radar cross section of a target is the (fictional) area intercepting that amount of power  which. when scattered equally in all directions, produces an echo at the radar equal to that  from the target; or in other terms,  power reflected toward source/unit solid angle  6= Er - = lim 47rn2 f. 
 (Receiver detection-criteria for compensating the effects of a change in clutter sta-  tistics with high resolution are discussed later in this section.) Third, if the pulse is too short, it  might encompass only part of a large target such as a ship, and the target cross section might  be reduced. However, if the echoes from the various parts of a large target are displayed  without collapsing loss and if the operator knows the general shape of the target, there will be  little, if any, loss in detectability.  Antenna beamwidth. 
 However, it was also reported that following tuition from TRE (a Mr Mould, see authors of reference [3]o fc h a p t e r 8) the radar operator was able to learn how to manipulate the controls to successfully home in to a target down to short range in a heavy sea. The operator alsoreported that sometimes the target would disappear over an interval from 4 or 5 miles range down to about 2 miles range, before reappearing again. A possible reason for this is discussed in chapter 7, looking at theoretical performance predictions. 
 On the other hand, software developed for general-purpose pro - cessors may only need to be recompiled in order to move it to a new processor. Tools  currently exist that synthesize C or Matlab code into an FPGA design, but these tools  are typically not very efficient. The evolution of design tools for FPGAs to address  these problems is an area of much research and development. 
 There are three basic methods for employing semiconductor diodes in digital phase  shifters, depending on the circuit used to obtain an individual phase bit. These are: (I) the  switched-line, (2) the hybrid-coupled, and (3) the loaded-line. The switched line was shown in  Fig. 
  
 3, p. 269, 1987. 28. 
 Three different angular separations of the targets are ( a) 0.30  antenna beamwidth, ( b) 0.75 antenna beamwidth, and ( c) 0.85 antenna  beamwidth. ch09.indd   46 12/15/07   6:08:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 NESS OF GROUND TRUTH  CALIBRATION OF THE EQUIPMENT  AND THE EXPERIMENTERS EXPERI 
  AND   D" OF THIS VALUE OVER A  TO  -(Z FREQUENCY SPAN 4HIS EXPERIMENT  PROVIDED THE FIRST DIRECT MEASUREMENTS OF THE SEA SURFACE SCATTERING COEFFICIENT /F COURSE  WHEN THE "RAGG RESONANT WAVES ARE NOT FULLY DEVELOPED  THE SCATTERING  COEFFICIENT WILL BE PROPORTIONATELY LESS  AS SHOWN IN &IGURE   COMPILED FROM DATA SETS RECORDED LOOKING UPWIND OR DOWNWIND WITH THE *INDALEE RADAR  /CCASIONS WHEN  THE WIND SPEED WAS INSUFFICIENT TO AROUSE THE "RAGG RESONANT WAVES TO SATURATION LEVELS YIELDED SCATTERING COEFFICIENT VALUES UP TO  D" BELOW THE PEAK VALUES ,OW SCATTERING COEFFICIENT VALUES CAN ALSO ARISE BECAUSE THE ANGULAR SPECTRUM OF  THE WAVE SYSTEM IS NOT BEING SAMPLED ALONG A DIRECTION THAT PRESENTS THE MAXIMUM AMPLITUDE COMPONENT AT THE "RAGG RESONANT WAVENUMBER 4HE DIREC TIONAL WAVE SPEC 
 52. Ruze, J.: Wide-angle Metal-plate Optics, Proc. IRE, vol. 
 With these additions a complete signal-processing system is obtained for suppressing clutter returns in a modern surveillance radar. A typical implementation of such an MTD processing system is shown in Fig. 15.6. 
 Ferritelimiter.Theferritelimiter46followed byadiodelimiter,hasalsoheenemployed asa solid-state receiverprotector.40,45The-diode isnecessary toreducethespikeleakagetoasafe levelsincetheferriteactingalonedoesnotoffersufficient suppression ofthespikeleakageat highpeakpower.Theferritediodelimiterhasfastrecovery time(canbeaslowasseveraltens ofnanoseconds), andifthepowerratingisnotexceeded, thelifeshouldbeessentially un­ limited.Thespikeandflatleakage islow,buttheinsertion lossisusuallyhigherandthe package isgenerally longerandheavierthanotherreceiver protectors. Exceptfortheinitial spike,theferritelimiterisanabsorptive deviceascompared tothegas-tube TRorthe TR-limiter whicharereflective. Therefore, theincident powerisabsorbed intheferritesothat theaverage powercapability canbeaproblem. 
 Dif- ficulties may be encountered in matching the radiating elements and in maintain- ing polarization purity. This geometry has not yet found use in radar systems. The discussions in this chapter will concentrate on planar phased arrays. 
 AES-25, no. 6, pp. 854–860,  November 1989. 
 IIIC meant that the upgrade to higher power was more straightforward.The main units of ASV Mk. VIC are illustrated in ﬁgures 4.25and4.26. These were: Modulator, type 158A; Transmitter –receiver TR. 
 SHIPS THAT MUST BE SATISFIED BETWEEN THE FIELDS BOTH ELECTRIC  AND MAGNETIC  JUST INSIDE  AND JUST OUTSIDE THE SURFACE OF THE OBSTACLE 4HOSE BOUNDARY CONDITIONS ARE PARTICULARLY SIMPLE FOR SOLID CONDUCTING OR DIELECTRIC OBJECTS 4HE BOUNDARY CONDITIONS INVOLVE ALL THREE COMPONENTS OF THE VECTOR FIELDS  AND  THE SURFACE OF THE BODY MUST COINCIDE WITH A COORDINATE OF THE GEOMETRICAL SYSTEM IN WHICH THE BODY IS DESCRIBED &OR EXAMPLE  THE COORDINATE  R   CONSTANT COULD REPRESENT  A SPHERICAL SURFACE 4HE SOLUTION OF THE WAVE EQUATION IS MOST USEFUL FOR THOSE SYSTEMS IN WHICH THE EQUATION IS SEPARABLE INTO ORDINARY DIFFERENTIAL EQUATIONS IN EACH OF THE VARIABLES 4HE SCATTERED FIELDS ARE TYPICALLY EXPRESSED IN TERMS OF INFINITE SERIES  THE COEFFICIENTS OF WHICH ARE TO BE DETERMINED IN THE ACTUAL SOLUTION OF THE PROBLEM /NCE OBTAINED  THE SOLUTION ALLOWS THE FIELDS TO BE CALCULATED AT ANY POINT IN SPACE  WHICH IN 2#3 PROBLEMS IS THE LIMIT AS THE DISTANCE FROM THE OBSTACLE BECOMES INFINITE 4HE SOLUTION OF THE WAVE EQUATION MAY THEN BE USED IN %Q  TO DETERMINE THE SCATTERING CROSS SECTION !SIDE FROM A FEW VERY SIMPLE OBJECTS  SUCH AS THE SPHERE AND THE INFINITE CIRCULAR  CYLINDER  THE SOLUTION FOR %Q  IS MORE ACADEMIC THAN PRACTICAL 4HE SOLUTION FOR OTHER STRUCTURES  SUCH AS INFINITE PARABOLIC AND ELLIPTIC CYLINDERS  ARE DIFFICULT AT BEST  AND FOR MANY STRUCTURES WHOSE SURFACES MAY COINCIDE WITH A COOR DINATE SYSTEM  THERE  IS NO CONVENIENT METHOD OF SOLUTION 4HE MOST USEFUL AND PRACTICAL OF THE EXACT SOLUTIONS AVAILABLE IS THAT OF THE PER 
 wet snowcover on vegetation tends to lower the return by as much as 6 dB.40 Measure­ ments made over snowfields near Thule, Greenland, showed the backscatter to be propor­ tional lo the square of the frequency over the frequency range from UHF to X band and at  grazing angles from 5 to 20°.47  Frequency dependence. Figure 13. l 1 shows an example of the frequency dependence of land  clutter for a particular grazing angle.37 Clutter from urban areas in these measurements is  independent of frequency; rural terrain shows no frequency dependence from L to X band; . 
 The ocean’s reflectivity is also a function of other factors,  including surfactants (such as oil slicks, either natural or anthropogenic), the air-sea  temperature difference, or the presence of large waves such as oceanic swell, but these  are of less significance for the present discussion. The reflection coefficient s  0 is nonlinear with respect to the wind parameters.  Figure 18.18 illustrates the response for one polarization, where the horizontal axis  is the relative wind direction, and the vertical axis is the normalized radar cross sec - tion. 
 21<1< Tuning: klystron. 203 magnelron. 199200 Twin-slah toroidal phaseshiner.294 Twistreflector. 
 Hall and W. W. Shrader32 © IEEE 2007 )40 20 0 60 8 0 100 120 1400.0050.010.020.050.10.20.30.40.50.60.70.80.90.950.980.990.995Probability That Residue Samples Are Less Than A Given Value of I3 I3 (dB)I3 Mean for Hard Li mitI3 Mean for Linear CaseN = 5 σfT = 0.05 3 N = 10 σfT = 0.02 7 N = 20 σfT = 0.01 3N = 40 σfT = 0.007N = 80 σfT = 0.003 FIGURE  2.71 After MTI processing of the hard-limited distributed clutter  sequence ( N = 20) and a target superimposed on the clutter sequence, the residue  spikes are distinctly different from the target returns. 
 (/2):/. 2!$!2   Óä°nÎ  * , +ROLIK AND 2 ( !NDERSON  h-AXIMUM LIKELIHOOD COORDINATE REGISTRATION FOR OVER 
 1975 International Radar Conference , pp. 499–504. (Reprinted in Kovaly.15) 30. 
 3). only forcertain special cases canube calculated rigorously; formost targets uhastobeinferred from theradar data themselves. Usually this cannot bedone inany uniform way because ofthefluctuation referred to,and itmay bewell toassert atthis point that intelligent useoftheformulas which weshall derive, inallof which uappears, requires anappreciation ofthese limitations. 
 11.8  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 batch-processed monolithic microwave integrated circuitry (MMIC) fabrication tech - nology allow for circuit functions to be processed into very, very small, conveniently  packaged chips. The wide bandgap semiconductors, such as SiC and GaN, are also  compatible with MMIC processing but are also capable of very high power output  levels. These semiconductors have material properties that lead to high breakdown  voltage with commensurately high channel currents—an order of magnitude higher  power output than GaAs (Table 11.1). 
 D-scope.AC-scopeinwhichtheblipsextendvertically togivearoughestimateordistance.. RECEIVERS, DISPLAYS, AND DUPLEXERS 355  E-scope. An intensity-modulated rectangular display with distance indicated by the horizontal coordinate  and elevation angle by the vertical coordinate. 
 TIME OR NEAR 
 ch13.indd   72 12/17/07   2:41:17 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 DOPPLERv  TARGETS THROUGH THE  
 This is a simpler, albeit less accurate, method. It is based on calculating the reduction in  signal power and thus does not depend on the probability of detection. It applies for detection  probabilities in the vicinity of 0.50, but it is used as an approximation with other values as a  matter of convenience. 
 Conf ., Atlanta, GA, 1974, pp, 340–345. 26. R. 
 54. Carpentier, M. H.: "Radars: New Concepts," Gordon and Breach, New York, 1968, sec. 
 RANGE AIRBORNE AIR SURVEILLANCE IN THE PRESENCE  OF CLUTTER L 3TABLE COMPONENTS AND SUBSYSTEMS AND ULTRALOW SIDELOBE ANTENNAS THAT ALLOWED  HIGH 
 MTI ANU PULSE DOPPLER RADAR 113  used ti1e filter is called recursive. Using the Z-Lransform as the basis for design it is possible in  principle to synthesize almost any frequency-response function.2•11-13  The canonical configuration is useful for conceptual purposes, but it may not always be  desirable to design a filter in this manner. White and Ruvin2 state that the canonical  configuration may be broken into cascaded sections, no section having more than two delay  elements. 
 AnOTHradardesigned forthedetection ofaircraftatrangesoutto4000kmmighthave, forexample, anaverage powerofseveralhundreds ofkilowatts ormore,antenna gainsfrom about20to30dB,andoperating frequencies fromseveralmegahertz toseveral tensof megahertz. Antennas mustbelargeinordertoobtainreasonably narrow beamwidths. The antenna horizontal lengthmightbe300morgreater.Thetransmitted waveform canbepulse, CW,FM-CW, FM(chirp)pulse,orotherpulse-compression codedwaveforms. 
 Sensors 2019 ,19, 1649 On the other side, at a lower resolution achieved by RD in the range direction, a higher rejection of side lobes is obtained, showing that the clean aspect of the focused image is due to a higher smoothing of range lines. For the two focused images, a comparison of the amplitude statistics for the images focused with standard RD approach and B-SAR are plotted in Figure 11. What is evident is a close adherence of the statistics of the B-SAR image to the RD one, showing anyway a more compactness in the values, symptom of an imperfect focusing of highest peaks for this approximated method. 
 SIDELOBE LEVEL -33,   IT IS NECESSARY TO COMPARE  THIS ENERGY WITH THE PEAK OF THE PATTERN OF AN ARRAY OF  . ELEMENTS SO THAT THE MEAN 
 15, pp. 9–14, June 2000.  9. 
 8 Detection No. 9 1 4.2 1.2 ∞ 2 5.4 3.1 7.2 3 6.3 ∞ ∞ *(from G. V . 
 This method requires more complicated and wider-band transmitting and receiving equipment than dothepulsed methods which involve time sharing. THE RADIO-FREQUENCY EQUIPMENT Inselecting theradio-frequency equipment, therequirements tobemet and theoperational conditions must becarefully considered. Among the important factors are the station locations (land-, water-, orair-based), themaximum range required, thetypes ofinterference tobemet, and the nature ofthe data tobetransmitted. 
 This al- lows one to replace the gradient of Green's function with Vi); = /JkIIi0S (11.13) i|i0 = e~ikr ' seikR°I^R0 (11.14) where r is the position vector of integration patch dS and s is a unit vector point- ing from an origin in or near the object to the far-field observation point, usually . back toward the radar.29 R0 is the distance from the origin of the object to the far-field observation point. The second is the tangent plane approximation, in which the tangential field components n x E and n x H are approximated by their geometric optics val- ues. 
 Multiple beams from separate transmitter-receiver systems can be accurately settothe same azimuth angle. This property isvery desirable ifthe system istobeequipped for work with radar beacons. Open mesh oragrid structure can beused forthereflector surface toreduce wind resistance. 
  
 Often the airfrom the magnetron cooling blower can besodirected astodowhat additional cooling is needed. Subunits tightly enclosed forreasons ofelectrical shielding may, however, need additional circulation. Where thefree flow ofexternal airthrough ther-fhead isblocked off, asitmust bebyapressure housing, theproblem oftransferring theheat totheoutside aircan easily bealimiting factor indesign. 
 Richter: An Analytical Study of Tropospheric Structure as  Seen by High-Resolution Radar, J. Arm. Sci., vol. 
 Therefore any thermal noise generated in the antenna must be added to the noise represented by these curves. In most practical cases, a ground noise-temperature component must also be added because part of the total antenna pattern is directed toward the ground. (This will be true because of sidelobes and backlobes even if the main beam is pointed upward.) But then also the sky-noise component given by Fig. 
 Even a chopper receiver, in the simplest video version, may not give warning at sufficient range to prevent consequences. It should not be concluded that CW radar has all these advantages without corresponding disadvantages. Spillover, the direct leakage of the transmitter and its accompanying noise into the receiver, is a severe problem. 
 Ifitdoes, this signal will arrive 690 psec after thenext trans- mitted pulse, inexact imitation ofanecho from atarget at64miles Todecide how serious acomplication the possibility ofa“second time around echo, ”asitiscalled, presents, two cases must becarefully distinguished. 1.Targets beyond 186 miles are not ofinteresL The second-time- around echo isanuisance only. Itwould bewell toget rid ofitifthere were some way todoso;ifthere isnot, itwould be desirable toidentify itasaninterloper. 
 TIMES NECESSARY FOR MONOPULSE OPERATION 4HE #ASSEGRAIN DUAL REFLECTOR ANTENNA &IGURE    DERIVED FROM OPTICAL TELE 
 19,   O. M. Phillips and K. 
 PROPAGATION OF RADAR WAVES 469  66. Mumford, W W.: Heat Stress Due to RF Radiation, Proc. IEEE; vol. 
 9.6 ANTENNA-RELATEDECCM Since the antenna represents the transducer between the radar and the environ- ment, it is the first line of defense against jamming. The directivity of the antenna in the transmission and reception phases allows space discrimination to be used as an ECCM strategy. Techniques for space discrimination include antenna cov- erage and scan control, reduction of main-beam width, low sidelobes, sidelobe blanking, sidelobe cancelers, and adaptive array systems. 
                    
 4.25 Pulse Compression Systems  .............................  4.27  Stability Improvement by Feedback or  Feedforward  ....................................................  4.30  4.7 Transmitter Spectrum Control  ................................ 
 Early radio altimeters  were, in effect, a normal pulse-sender and echo-detector,  and measured heights with a considerable degree of  accuracy. But they fell into disuse because at any  . TRAVEL BY BEACON 163  distance from the ground less than about 400 feet they  proved unreliable. 
 NOISE AMPLIFIER AND A HIGH 
 Equipment considerations. The synthetic-aperture radar requires a coherent reference signal  and means for storing and processing the radar echoes. The coherent reference is necessary  since an angle measurement is a measurement of phase from spatially separate positions. 
 the signals will he reflected by the short circuits located farther down the transmission lines.  The signals at ports 2 and 3, arter reflection from either the diode switches or the short  circuits. combine at port 4. 
 At times, atmospheric conditions might cause more than usual  bending of the radar rays, with the result that the radar range will be considerably increased.  This condition is called superrefraction, or ducting, and is a form of anomalous propagaiion.  It is not necessarily a desirable conditioh since it cannot be relied upon. 
 ;;=-J 
 The microburst and its effects on an aircraft during takeoff or landing are depicted in Fig. 23.4. The microburst is simply a small-scale, short-duration downdraft emanating from a convective storm. 
 278 ANTENNAS, SCANNERS, AND STABILIZATION [SEC.94 Yagiarray has been widely used forwavelengths ofseveral decimeters; anexample isshown inFig. 6.30. Anend-fire antenna can also consist ofapolyrod (arodofpolystyrene) ofappropriate dimensions, into oneend i (a)E\\, \\\\ K\\(b)..Fm.9.1O.—A paraboloid reflector may bedistorted invarious ways inorder toproduce a fanbeam,. 
 IEEE 1975 l11cen1<1timwl Radar Conference. Arlington, Va .• Apr. 21-23, 1975. 
 MATION IS NECESSARY TO OBTAIN USEFUL QUANTITATIVE RESULTS FROM THEM 4HE METHODS OF APPROXIMATION RELATE TO THE TWO METHODS OF FORMULATING THE '"60  3MALL 
 Arlington. Va.,Apr.21--23.1975. IFFEPublication 75CHO93X-1AES. 
 Abeautiful example ofthe change ofsignal power with 1,aspredicted bythis formula, is given inFig. 3,6, which sho~vs sucmssive frames ofaphotographic recording ofanA-scope trace at+T-sec intervals. These recordings \rere ob- tained onDeer Island inBoston Harbor, The signal onthe right-hand side isreceived from theantenna towers ofRadio Station WBZ. 
 Larson, T. R., A Microstrip Honeycomb Array for the Low Altitude Space Based Ra- dar Mission, Ball Aerospace Systems Division, Rept. F81-06, August 1981. 
 ................................ ................................  14  MDS - Echo  ................................ 
 In this section, the radar may be thought of as carried by an  aircraft. but sirnilar argunie~its apply for satellites or other moving vehicles.  Figure 14.1 shows an aircraft traveling with a constant velocity o along a straight path. 
 Because the latter are much more significant in backscattering computations than the former, we focus here on edge diffraction. The theory assumes that a ray striking an edge excites a cone of diffracted rays, as in Fig. 11.26. 
 But linear frequency modulation isnot easy, and forsingle targets the operation isnot greatly affected byachange from linear tosinusoidal frequency modulation. The difference frequency then varies sinusoidally with time, but the important point remains, namely that themean magnitude ofthe difference frequency de- pends onthe range. Sinusoidal e frequency modulation istherefore ~radopted since itrequires simpler 2 apparatus and accomplishes the ~ same result. 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 resorting to frequency agility and/or frequency diversity. Some radars incorporate an  AFS device that allows the radar frequency to be tuned to that part of the spectrum  containing the minimum jamming energy.133,138 In accordance with the search-radar equation (see Section 24.12), ECCM perfor - mance appears (explicitly) to be insensitive to frequency. 
 Table 8.3 provides a comparison of NLFM waveforms with weighted and  unweighted LFM for different values of the target radial velocity in terms of peak  and average time sidelobe levels and SNR loss. The NLFM waveform shows better FIGURE   8. 11 Peak time sidelobe level for a sine-based NLFM waveform as  a function of k-factor ( Courtesy of Dr. 
 T,T2 Tl 2T3)112( 2E)'12 Zrc 1 2 + _1_2 + 2 + 1 __  3 3 15 3 N0 trapezoidal pulse (11.31)  This reduces to the expression for a rectangular pulse [Eq. ( l l.29)] as the trapezoidal pulse  becomes more rectangular, that is, when T1 = r/2 ~ T2•  For the triangular pulse, we set T1 = 0 in Eq. ( 11.31) and let 2 T2 r 8. 
 Hertz was able to show thatelectromagnetic waves travelled in straight lines and that they can bereﬂected from a metal object just as light waves are reﬂected by a mirror. In1904theGermanengineer,ChristianHulsmeyerobtainedapatentfora device capable of detecting ships. This device was demonstrated to theGerman navy, but failed to arouse interest probably due in part to its verylimited range. 
 TER ARISING FROM THE VARIATION OF WIND VELOCITY WITH HEIGHT #HAFF MOVES WITH THE LOCAL WIND  AND THERE ARE WAYS ADAPTIVE -4) AND OPTIMUM DOPPLER PROCESSING o  TO MAKE AN  -4) NULL OUT BOTH MOVING AND STATIONARY UNWANTED ECHOES   4HERE ARE TWO BASIC  DOPPLER FILTERING TECHNIQUES THAT ARE USED 4HE FIRST IS THE -4)  WHICH EMPLOYS A 02& THAT PROVIDES UNAMBIGUOUS RANGE COVERAGE WHILE USING A COMB DOPPLER FILTER WHOSE NULLS ARE TUNED TO THE AVERAGE RADIAL SPEED OF CHAFF  4HE SECOND IS THE PULSE DOPPLER   WHICH CAN USE A HIGH 02& TO PROVIDE UNAMBIGUOUS DOPPLER COVERAGE IN CONJUNCTION WITH A DOPPLER FILTER BANK  ALLOWING SEPARATION OF TARGET FROM THE CHAFF  ! PROBLEM WITH  CHAFF MIGHT BE WHEN THERE IS A SIGNIFICANT WIND SHEAR IN THE ATMOSPHERE 7ITH WIND SHEAR  THE DOPPLER SPECTRUM FROM CHAFF CAN HAVE A WIDE SPECTRAL WIDTH UNLESS THE ELEVA 
 Binary Integrator. The binary integrator is also known as the dual-threshold detector, M-out-of-N detector, or rank detector (see "Nonparametric Detectors" later in this section), and numerous individuals have studied it.14~18 As shown in Fig. 8.3d, the input samples are quantized to O or 1, depending on whether or not they are less than a threshold T1. 
 ENTRY  AFTER 2 #OOPERMANR Ú &IFTH )NTERNATIONAL #ONFERENCE ON )NFORMATION &USION  VOL                       
 523–530. 46. R. 
 Although it is  unachievable in practice, the objective is to create a high-resolution, thumbtack-like  central spike with a clear area around it. Measurement is then performed on the high- resolution central spike. The range resolution or compressed-pulse width is determined  by the total bandwidth of all the pulses, and the doppler resolution is determined by the  reciprocal of the waveform duration T. 
   PP n    % - "RACALENTE  7 , *ONES  AND * 7 *OHNSON  h4HE 3EASATA SATELLITE SCATTEROMETER v  )%%%  4RANS  VOL /% 
 R.: Quaternary Codes for Pulsed Radar, pp. 400-408.  9. 
 111  c = velocity of propagatiori, rn/s  A/'= frequeticy cxctlrsiori. t1z  Since the output of tlic freqitet~cy counter N is an integer, ttie rarige will be an integral multiple  of ci(4 A/ ) atid \\fill givc rise to a qitantizatiorl error equal to  IJ 6 R (rn ) = 41' (MHz)  Note tllat tile fixed error is iridepcndent of the range arid carrier frequency and is a fulictiotl of  tlie frequericy exct~rsiori only. Large frequency excursions are necessary if the fixed error is to  he sr11aIl. 
 Themeasure oftheerroristherootmeansquareofthedifference between themeasured valueandthetrue value.Thedisturbance limiting theaccuracy oftheradarmeasurement isassumed tobethe receiver noise.Itisfurthermore assumed thatbiaserrorshavebeenremoved. Itwillbeshownthatthermserror(jMofaradarmeasurement Mcanbeexpressed as kM(jM=---=fiE/No(11.1) whereEisthereceived signalenergy.No.isthenoisepowerperunitbandwidth, andkisa constant whosevalueisoftheorderofunity.Foratime-delay measurement, kdepends onthe shapeofthefrequency spectrum 5(1),andMistherisetimeofthepulse;foradoppler frequcncy measurement, kdepends ontheshapeofthetimewaveform s(t)andMisthe spectral resolution, orthereciprocal oftheobservation time;andforananglemeasurement k depends ontheshapeoftheaperture illumination A(x),andMisthebeamwidth. Range-accuracy -leading-edge measurement. 
 He received his doctorate in electrical engineering from Johns Hopkins University, where he also earned B.E. and M.S.E. degrees. 
 Conformal arrays would have application for flush-mounted airborne radar antennas,  especially on conical and ogive surfaces. The cylinder, truncated cone, and the hemisphere are  possible antenna shapes for shipboard or surface applications. Such conformal arrays have  been considered for radar but they do not appear suitable for general application. 
 BETWEEN 
 Practical three-dimensional Luneburg lenses have been constructed of a large number of  spherical shells, each of constant index of refraction. Discrete changes in index of refraction  approximate a continuous variation. In one example of a Luneburg lens 10 concentric spheri- + --  cal shells are arranged one within the ~ther.~~.~~ The dielectric constant of the individual shells  varies from 1.1 to 2.0 in increments of 0.1. 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°{Ç  $ETECTION 
 1801-1811. November, 1968.  104. 
 The only problem one is spared is the phase locking, which is usually required when working with sources. Fortunately, well-designed multipliers usually add little phase noise to a radar (above that to be expected from the increased FM deviation produced by the multiplication process). When 100 sources, consisting of a crystal oscillator plus a multiplier chain, were supplied by a subcontractor to a military radar program, the only ones that were unable to meet an extremely severe specifica- tion were ones that had substandard crystals in the oscillator.16 Because of the similarity of methods, measurement of noise in pulsed trans- mitters will merely be sketched. 
 Further, a high degree of automation is essential to keep up  with the changing environment. A comparison of principle design parameters of several current and former opera - tional HF skywave radars is presented in Table 20.2, illustrating the diversity of engi - neering solutions that have been implemented to meet specific mission objectives.  Jindalee  Stage BJORN- LavertonAN/FPS-118  ECRS/WCRSAN/TPS-71 ROTHR NostradamusSteel Yard (Komsomolsk  na Amur) Developer DSTO,  AustraliaTelecom  Australia GEC-Marconi  UK RLM  USA-AustraliaGeneral Electric  USARaytheon  USAONERA,  FranceNIIDAR,  Russia Year of first  target detections1982 2000 1983 1987 1994 1977 Configuration Quasi- monostaticQuasi- monostaticQuasi- monostaticQuasi- monostaticTrue  monostaticQuasi- monostatic Tx – Rx site  separation (km)100 80 160 100, 160 n/a Max. 
 568 INTRODUCTION TO RADAR SYSTEMS  43. McAttlay, R. I.: Intcrkrometer Design for 1llcv;ttion Atlglc l<stimation, II.:t-:l: .I'rtrtl.s.. 
 The upper beam, weighted to produce low sidelobes, is placed a degree or so above the lower beam so that the indirect-path echo is rejected by the sidelobes of the upper beam while the direct-path echo is received at high gain. This approach tends to minimize the amount of indirect-path energy in the two beams while maintaining coverage on the horizon. The performance of the low-angle squinted-sum-beam technique also differs from that of a conventional stacked-beam pair, for two reasons. 
 4(% 
 paraboloid has. SEC. 9.17] STABILIZATION OF’ THE BEAM 307 been removed from thegently curved support casting, which can beseen supported bet\veen the tilt bearings atthe tips ofthe yoke. 
 Madrigal Database made the incoherent scattering radar data available. We appreciate their works. Conﬂicts of Interest: The authors declare no conﬂict of interest. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.56  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 where ra is the along-track resolution, ry is the ground-range resolution, and rg is the  gray-level resolution. 
 In some devices. less noise is obtained under mismatched, rather than matched, conditions. In  spite of definitions. 
 In each case the comparator is arranged to use a different set of elements for the sum and differ- ence beams. In some cases this is accomplished with oversized feeds that permit two modes with the sum excitation. Hannan24 has tabulated results for several configurations, as summarized in Table 6.1. 
 UNIT I    Basics of Radar: Introduction, Maximum Unambiguous Range, Radar Waveforms, Simple form  of Radar  Equation, Radar Block Diagram and Operation, Radar Frequencies and Applicati ons,  Prediction of Range Performance, Minimum Detectable Signal, Receiver Noise, Modified Radar  Range Equation, Related Problems.   Radar Equation:  SNR,  Envelope Detector -False Alarm  Time and Probability, Integration of Radar  Pulses, Radar Cross Section of T argets (simple targets - sphere, cone -sphere),  Transmitter  Power, PRF and Range Ambiguities, System Losses (qualitative treatment), Related Problems.    UNIT -II  CW and Frequency Modulated Radar:  Doppler Effect, CW Radar – Block Diagram, Isolation  between  Transmitter and Receiver, Non -zero IF Receiver, Receiver Bandwidth Requirements,  Applications of CW  radar, Related Problems. 
 circulntor. alid 28-V power supply. Ttie antenna rotates mechanically iri  ;i~irnutll and scans clec~ronically in elevation. 
 17.4.2 Some form of signal generator—usually electromagnetic-geared tothe scanner pro- duces periodic signals offrequency proportional tothe scanner velocity and suitable forthepulse recurrence frequency. These signals control a blocking oscillator orsome other device toproduce sharp pulses which are then coded fortransmission over the relay link. The third pulse ofthe code (from point EofFig. 
 CONVERSION TECHNIQUES )N THIS APPROACH  THE COMPLEX ENVELOPE SEQUENCE IS EVALUATED BY DIGITAL SIGNAL PROCESSING OF !$ CONVERTER SAMPLES AT THE FINAL )& OUTPUT OF THE RECEIVER  RATHER THAN BY SEPARATE !$ CONVERSION OF BASEBAND ANALOG  ) AND 1 COMPONENTS n $IGITAL DOWN 
 Elec. Enyrs.,  vol. 49, pp. 
 At the same time, we deﬁne a slant range sequence Rn. It stores the slant range corresponding to each element in the sequence DEMs , which can be expressed as: Rn=⎭bracketleftBig Rs1,Rs2, ..., Rs j, ..., RsM⎭bracketrightBig (j=1, 2, ..., M ) (29) 2. We calculate the ground range sequence Rgusing the geometric relationship between the sequence DEMs and the sequence Rn. 
 Scptctttl~cr. 1972.  25. 
 This means that at these higher frequencies the  clutter signal will be strongly affected by atmospheric absorption effects, and conse - quently the surface-related cross section inferred from the received signal strength in  any given measurement will depend upon the path length. Moreover, the role of sea  spray  in both scattering and absorption will certainly be more important than at the  lower microwave frequencies. It is difficult to find clutter data at frequencies above Ka band, although H- and  V-polarized returns at 95 GHz at a grazing angle of 1° were reported, both with  values close to –40 dB.55,56 The Spectrum of Sea Clutter. 
 ENT GAIN   ' #  F    WHICH AT THE FILTER PEAK HAS A VALUE  '# MAX 4HE COHERENT GAIN OF  A DOPPLER FILTER IS EQUAL TO THE INCREASE IN SIGNAL 
 Then  MSSL = −47 dB  or  MSSL 2 1 0 = × =− + +−52 21( )P P PNA aσ σ ηφ  FIGURE 13.19  Sidelobe level to be held with probability P (after J. L. Allen73) ch13.indd   32 12/17/07   2:40:17 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The SSCM for ship characterization using polarimetric SAR. In Proceedings of the 2003 IEEE International Geoscience and Remote Sensing Symposium, IGARSS’03, Toulouse, France, 21–25 July 2003; Volume 1, pp. 194–196. 
 TER CANCELLATION PERFORMANCE IS DRIVEN BY MAIN 
 44 Measurement-based theoretical s 0 variations for first-year and  multiyear sea ice. Ranges are determined by using known variations of ice charac - teristics. ( after Y. 
 ING DESIGNANALYSES &IGURE  SHOWS A SNAPSHOT OF THE 7ORKBENCH '5) WINDOW  INCLUDING A RENDERING OF AN OFFSET 
 (Copyright 1966, IEEE.9)VERTICAL POLARIZATION HORIZONTAL POLARIZATION EXPERIMENTAL GEOMETRIC DIFFRACTION[THEORY PHYSICALOPTICSGEOMETRIC DIFFRACTION THEORY EXPERIMENTAL PHYSICALOPTICSRADAR CROSS SECTION a- (dBsrn) . These undulating patterns follow a sin x/x variation quite closely for aspect angles out to about 30°, but beyond that angle the two patterns differ by progres- sively wider margins. The sin x/x behavior is characteristic of a uniformly illumi- nated aperture, but unlike the one-way illumination function encountered in an- tenna work, the argument x for a flat plate includes a two-way (round-trip) illumination function. 
 This effect is caused by quartic and higher-order even terms in the series. Its effect will be noted, for example, when Vt^2 __ ^ Intermodulation is reduced in some mixer designs by forward-biasing the mixer diodes to reduce the higher-order curvature. The Balanced Mixer. 
 M. Greco, F. Gini, and A. 
 ACTING !'# IS GENERALLY THE PREFERRED CHOICE FOR MAXIMIZING OVERALL TRACKING ACCURACY (IGH 
 1964 Inrertrational Conv. Military Electronics, Sept. 14-16, pp. 
 A synthetic aperture mode can be used to observe limited regions with a resolution of about 200 m. Other missions using radar are planned for ocean scatterometry and altime- ters. Scatterometers are used to obtain accurate measurement of global surface winds for oceanography and meteorology. 
 The lock-follow functions on ASV Mk. VIA (from [ 8]).Airborne Maritime Surveillance Radar, Volume 1 4-9. pointing direction of the antenna in order to track the target in azimuth. 
 Changes of the binomial feedforward coefficients and/or the addition of feedback modify the filter characteristics. Within this chapter, refer- ence to binomial-weight cancelers refers to cancelers with the 2" sin" (^fdT) transfer function. Figures 15.21 to 15.23 represent typical velocity response curves obtainable from one-, two-, and three-delay cancelers. 
 ERROR 
 &- WAVEFORM /NE OF THE PRIMARY DISADVANTAGES OF THE NONLINEAR 
 The Royal Society has amassed a considerable amount  of data on the migration of birds, and now that we have  discovered that large flocks of birds give a quite reason-  able reading on the average radar equipment we could  use radar technique to plot the course of migratory  flocks, and thus discover much that organizations of  bird-watchers might never know, when flocks cross large  tracts of ocean. Ornithological research in the future  can hardly be dissociated from radar, any more than can  weather-forecasting.  Radar meteorology, however, must be along two lines  of development. 
 LENGTH SEQUENCES MAY BE  DETERMINED FROM A STUDY OF PRIMITIVE AND IRREDUCIBLE POLYNOMIALS !N EXTENSIVE LIST OF THESE POLYNOMIALS IS GIVEN BY 0ETERSON AND 7ELDON   !LTHOUGH MAXIMAL 
 Finally, the ﬁnal fan DBS image is formed by stitching all the DBS sub-images based on the a ﬃne transformation [ 9]. The comparison of di ﬀerent super-resolution methods is demonstrated in the following section. 4. 
 The IF sum-signal output is detected and provides the video input to . FIG. 18.8 Microwave-comparator circuitry used with a four-horn mono- pulse feed. 
 65D, pp. 101-l lO, 1961. 1111' FI.ITTRONICALI.Y STEERED PHASED ARRAY ANTENNA IN RADAR 341  102. 
 Anotl\cr radar area that has seen much development is that of the electronically steered  ptiased-array antenna. In tlie first edition, the radar antenna was the subject of a single  cliaptcr. I11 tliis edition, one chapter covers the conventional radar antenna (Chap. 
 Upon arrival atthefirst grid theelectrons have avelocity corresponding to300 volts. Itwillbeassumed that oscil- lations exist inthe cavity. Elec- trons will then alternately be accelerated and decelerated bythe r-ffield across thegrids. 
 If the output of the receiver is proportional to the logarithm of the input  envelope, it is called a logarithmic receiver. It finds application where large variations of input  signals are expected. It might be used to prevent receiver saturation or to reduce the effects  of unwanted clutter targets in certain types of non-MTI radar receivers (Sec. 
 The important difference—and, indeed,  the factor which makes the wave-guide a workable pro-  position for radar—is that the strength of the waves in  free space falls off as the reciprocal of the distance,  while, in a tube made of a perfect conductor, there would  be no reduction in strength as the wave-form travels  along the tube. In practice, using copper tubes as wave-  guides, the attenuation is about 20 per cent. for 50 yards  of the guide. 
 A. Walther, C. L. 
 Stagger tuning of a  klystron is not strictly analogous to stagger tuning a conventional IF amplifier because inter­ actions amoQ_g cavities can cause the tuning of one cavity to affect the tuning of the others. The  S band VA-87, a four-cavity klystron amplifier, has a synchronously tuned half-power band­ width of 20 MHz and a gain of 61 dB. When tuned for maximum power the bandwidth is  increased to 27 MIiz and the gain reduced to 57.6 dB.9 By stagger tuning the various cavities  the half-power bandwidth can be increased to 77 MHz (about 2.8 percent bandwidth), but  with a concurrent decrease in gain to 44 dB·. 
 Scanning Pencil-Beam Radars. Another method of achieving 3D volumetric coverage suitable for high-air-traffic situations is the scanning pencil-beam radar. The most common radars in this class obtain high volumetric coverage by em- ploying an antenna feed technique which electronically scans a narrow pencil- type beam through the elevation coverage as it rotates in azimuth, producing an azimuth-elevation scanning pattern similar to that of a TV raster scan. 
 114. Ewell, G. W., Bistatic Radar Cross Section Measurements, chap. 
 TION  WILL REDUCE THE SET OF DETECTIONS TO  THOSE WITHIN THE DOP PLER CORRELATION WINDOW  &OR CASES WHERE THIS IS NOT FEASIBLE GENERALLY THE LOWER MEDIUM 02&S   UTILIZING BOTH  RANGE AND DOPPLER CORRELATION WILL REDUCE GHOSTS 5SING MONOPULSE MEASUREMENTS TO  SEGREGATE AND BIN TARGETS THAT ARE DISTINGUISHABLE IN ANGLE CAN ALSO REDUCE GHOSTING WHEN THERE ARE A SIGNIFICANT NUMBER OF DETECTIONS IN A DWELL ! TYPICAL MEDIUM 
 10.19.—An array ofanode blocks showing theeffect ofwavelength andpulse power output. Top row—10 cm,pulse power 2500 to0.1kw;second row—3 cm,pulse power 600to0,025 kw;single block—1.25 cm,80kw. observed. 
 Polarization. Figure13.3indicates thathorizontal polarization resultsinlessseaclutterthan vertical, fortheseaconditions whichapplytothatdata.Themajority ofradarsthatoperate ov~rtheseausuallyemployhorizontal polarization. Air-surveillance radarswithhorizontal polarization achieve greater rangethanwithvertical polarization because ofthehigher renection coefficient ofhorizontal polarization (Sec.12.2).Afirmconclusion infavorofone polarization ortheotherisdifficult tomakeforacivilmarineradar,butmostsetsuse horizontal polarization.21Athighseastatesthedifference between horizontal andvertical polarization issaidtodisappear.22 Horizontal polarization, aswasmentioned inSec.13.3,hasaprobability densityfuncticn whichdeviates fromRayleigh morethandoesverticalpolarization whenthepulsewidthsare short.Thenon-Rayleigh natureofthecluttermustbeproperly considered inthedetector designiflargeincreases intheminimum detectable signal-to-clutter ratiosaretobeavoided, Pulsewidth.Theradarequation thatappliestothedetection oftargetsinsurfaceclutteratlow grazingangles(Eq.13.8)showsthat,allotherfactorsremaining constant, theshorterthepulse widththegreaterwillbethemaximum' range.Decreasing thepulsewidthdecreases the amount ofclutterwithwhichthetargetmustcompete. 
 aa  BBFOR     WHERE 4 IS THE PULSEWIDTH  " IS THE SWEPT BANDWIDTH  AND A  IS DEFINED AS    BA A a   c 
   EACH BEAM HAS BEEN SERVICED CONTINUOUSLY WITH ITS OWN RECEIVER "ACKGROUND NOISE DATA USED IN CONJUNCTION WITH THE BACKSCATTER DATA FOR THE %XCESS 0OWER ANALYSIS IS COL 
 229 Faraday rotator.296 FastFourierTransform. 123 andmultiple beams.317 fJDratio.antenna. 239 Feeds: arrayantenna. 
 ( 13.3) and taking  G = n2/08</J8,69 the clutter radar equation is  C = 3_~r__Aea0  64R2 sin <p ( 13.9)  The clutter power is seen to vary inversely as the square of the range. Equation (13.9) applies.  for example, to the signal received from the ground by a radar altimeter. 
 Thus, the processor must usually  correct for range migration . However, this is typically accomplished by modern SAR  processing methods.3 For spotlight SAR, the polar format algorithm3,11 is often used  to accomplish this correction. Other Processing Functions. 
 R. Soc. London , vol. 
 TRACKING CIRCUITS )N CONCLUSION  THESE DEVICES HAVE A PLACE IN THE RADAR BUT NOT AS MEANS FOR FIGHTING THE %#- BATTLE )N SUMMARY  THERE ISNT MUCH THAT HAS BEEN DONE IN THE RECEIVER TO COMBAT %#-  OTHER THAN TO INSURE THERE IS A GOOD RECEIVER THAT DOES ITS JOB 4ODAY  MODERN PHASED 
 332 INTRODUCTION TO RADAR SYSTEMS  One approach is to try all possible element locations with the given number of elements  and select that arrangement which produces the best result. This technique, called rota/  e1H1111eri11io11, is generally impractical because of the large number of possible solutions that  would need to be examined. An equivalent result, with less computation, is to apply dy11a111ic  programming, a method for determining the optimum solution to a multistage problem by  optimizing each stage of the problem on the basis of the input to that stage. 
 The propagating wave will be bent  downward from a straight line more than normal. As the refractivity gradient continues  to decrease, the radius of curvature for the wave path will approach the radius of cur - vature for the Earth. The refractivity gradient for which the two radii of curvature are  equal is referred to as the critical gradient . 
 FIGURE 17.10  SAR image of a moving target using multiple subapertures for clutter   cancellation (simulated data): ( a) adaptive processing and ( b) adaptive processing plus SAR  (after S. Barbarossa and A. Farina43 © IEEE 1994 ) ch17.indd   25 12/17/07   6:49:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Figure 4.26. Photographs of ASV Mk. VIC units at TRE [©Crown copyright, released under OGL v3.0; (a) A5274 and (b) A5275, MRATHS].Airborne Maritime Surveillance Radar, Volume 1 4-22. 
 MTT·l I. pp. 291-296, September, 1963. 
 OTHER RADAR TOPICS 519  The resolution or the unfocused SAR does not depend on the size of the real antenna. (In a  sidelooking SAR the cross-range resolution is also called the ,along-track or azimuth  resolution.)  The limit on resolution due to operation in the far field can be overcome by correcting the  received signal for the curvature of the spherical wavefront experienced when the target is  within the Fresnel region of the synthetic array. At each "element" of the synthetic array  antenna a phase correction A</> = 2nx2 / lR is applied, where x is the distance from the center of  the synthetic aperture. 
 One kind of error is  to mistake noise for signal when only noise is present. This occurs whenever the noise is large  enough to exceed the threshold level. In statistical detection theory it is sometimes called a  type I error. 
 The range beyond which targets appear as second-time-around  echoes is called the 111axi111111n 1111ambiguous range and is  C  Runamb = lfp (1.2)  where fr = pulse repetition frequency, in Hz. A plot of the maximum unambiguous range as a  function of pulse repetition frequency is shown in Fig. l.l. 
 Vandemark, “Relationship between ERS scatterom - eter measurement and integrated wind and wave parameters,” J. Atmospheric and Oceanic  Technology , vol. 21, pp. 
 W. Rihaczek, “Radar signal design for target resolution,” Proc. IEEE , vol. 
 COMPRESSION  TECHNIQUES !S SUGGESTED IN THE TABLE  NEITHER OF THESE TWO EARLY ALTIMETERS INCLUDED A  WATER 
 For a three-phase code, P = 3, and the sequence is O, O, O, O, 2ir/3, 4W3, O, 4W3, 2ir/3. The autocorrelation function for the periodic sequence has time sidelobes of zero. For the aperiodic sequence, the time sidelobes are greater than zero. 
 Frequency agility is possible with the frequency of transmission changing at will from pulse to pulse or, with coding, within a pulse. Very high powers may be generated from a mul- tiplicity of amplifiers distributed across the aperture. Electronically controlled ar- ray antennas can give radars the flexibility needed to perform all the various functions in a way best suited for the specific task at hand. 
 pp. 331-336, May, 1960.  37. 
 POLARIZED % 
 B. Sweetman and J. Goodall, Lockheed F-117A , Oseola, WI: Motorbooks International  Publishers & Wholesalers, 1990. 
 Ithas been shown’ that the rate ofchange ofoscillator frequency averaged over allmodulation frequencies can beused inplace ofthe simple d~/dt ofEq. (3)asafigure ofmerit forlocal-oscillator stability. Table 16.5 shows some typical figures onlocal-oscillator stability. 
 The number of meander loops required is greater than £AJ. Other microwave dispersive networks include a waveguide operated near its cutoff frequency and stripline all-pass networks. If a section of rectangular waveguide is operated above its cutoff frequency, the time delay through the waveguide decreases with frequency. 
 especially if the clutter is stationary relative to the radar. Receiver noise  is usually decorrelated in a time equal to 1/B, where B = receiver (IF) bandwidth. The decor­ relation time of clutter is usually much greater than this. 
 0HASING #ALCULATIONS  ! COMPUTER IS USUALLY REQUIRED TO PERFORM THE  STEERING COMPUTATIONS FOR A PHASED ARRAY ANTENNA )T CAN COMPENSATE FOR MANY OF THE KNOWN PHASE ERRORS CAUSED BY THE MICROWAVE COMPONENTS  THE OPERATING ENVIRON 
 75--80, December, 1969.  46. Qucrido, 11. 
 7.4. It is generated by moving the parabolic contour over an arc of a circle  whose center is on the axis of the parabola. It is useful where a scan angle less than 120" is  required and where it is not convenient to scan the reflector itself. 
 88. Croney. J.: The Reduction of Sea and Rain Clutter in Marine Radars, J. 
 (13.2X) Attenuation (dB/km)=0.434l~; (~D3 )1m(-K)jAttenuation byprecipitation. Inthefrequency rangeforwhichRayleigh scattering applies (particles smallinsitecompared withthewavelength) theattenuation duetoabsorption is givenl1y wherethesummation isover1rn",Vistheparticle diameter incentimeters. ).isthe wavelength incentimeters, 1m(-K)istheimaginary partof-K,andKisafactorwhicll depends uponthedielectric constant oftheparticle. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar.  BISTATIC RADAR  23.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 The available database for terrain  and sea clutter at microwave frequen - cies consists of nine measurement  programs, which are summarized in  Table 23.4. 
 31•51•62 The name pipology is sometimes applied to the art of designing  and operating the radar display so as to optimize the operator's ability to detect target pips. (A  target pip is also called a blip.) It has also been found from experience that an operator should  not, in general, be required to perform his duties for more than one-half hour at one sitting.51 . 388 INTRODUCTION TO RADAR SYSTEMS  10.7 AUTOMATIC DETECTION  The function of the radar operator viewing the ordinary radar display is to recognize the  presence of targe_ts and extract their location. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft.  MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 Air-to-Surface Mode Suite. 
 Tuners. High-power magnetrons can be mechanically tuned over a 5 to 10 percent frequency range routinely, and in some cases as much as 25 percent. Rotary Tuning. 
 In Proceedings of the Igarss IEEE International Geoscience & Remote Sensing Symposium, Fort Worth, TX, USA, 23–28 July 2017. 2. Dreschler-Fischer, L.; Lavrova, O.; Seppke, B.; Gade, M.; Bocharova, T.; Serebryany, A.; Bestmann, O.Detecting and Tracking Small Scale Eddies in the Black Sea and the Baltic Sea using High-Resolution Radarsat-2 and Terrasar-x Imagery (dteddie). 
 To be useful in a radar transmitter amplifier, the transistor must be capable of oper - ating at the appropriate high frequency with good efficiency, while demonstrating  useful power gain with adequate thermal management properties to ensure high reli - ability. There is not one transistor type or one semiconductor material that is univer - sally useful across all the common radar bands from UHF through W band. In fact,  among the radar bands, there is often a different dominant device type, along with its  attendant design and fabrication methodologies, that offers the optimum performance  for that band. 
 The technique is referred to as the velocity-azimuth-display (VAD) technique. Browning and Wexler73 later showed how the technique could be extended to measure other parameters of the wind field including divergence and deformation. Baynton et al.49 show how the VAD can be applied in real time by using a color-enhanced radial velocity display. 
 The developmental characteristics of karst in Wuhan urban development area. Urban Geotech. Investig. 
 7\73Thecoherent component hasareflection coefficient whose amplitude andphasearefixedbyagivengeometry andseastate.Theterm"reflection coefficient" asusuallyfoundintheliterature isgenerally thatofthecoherent component. The incoherent, orfluctuating, component ofasurface-scattered signalischaracterized bya random phaseandamplitude. Theincoherent component oftheforward-scattered signalfrom aroughsurfacebehavesdifferently fromthecoherent component asafunctionofroughness. 
 Lett. 2016 ,13, 616–620. [ CrossRef ] 8. 
 CIVIL MARINE RADAR  22.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 requirements for the electronic navigation of ships, including VTS reporting systems,  are being examined by IMO and IALA, with the intention of determining a future   e-Navigation concept ( e for electronic /enhanced ). The continued need for racons or  a replacement technology will inevitably form part of this program. If the continuous  availability of precise positional information cannot be totally relied upon, then it is  probably essential that some form of ship-relative system to identify fixed naviga - tional marks is available. 
 Ur~forti~rlately, tlrc tl~iri ski11 required for good electrical properties is not consistent with good  rnecliar~ical ~voperties. 7'11is liniits the size arid the frequency of operation of thin-wall rigid  rado~lics.  (;round-based radonies rtiay utilize foam materials, such as polyester polyuretliane, of  low dielectric constarit and low loss tangent in a relatively thick-wall construction to meet  strtlctural requiremerits with excellent electrical performance over a wide frequency band. 
 BASED MULTISTATIC SITES ATTEMPT TO MEA 
 The frequency ofthe sweep sinusoid may bemany times the pulse repetition frequency, inwhich case the intensity grid ofthe. SEC. 6.51 REPRESENTATION OFTHEHORIZONTAL PLANE 167 CRT isused toblank the trace onallbut one sweep cycle; adelayed expanded sweep isthus produced (see Fig. 
 R. E.: Radiatiori Patterns of a Splierical Luneburg Lens with Simple Feeds, IRE Traru.,  vol. AP-6, pp. 
 E. Brookner, “Radar performance during propagation fades in the Mid-Atlantic region,” IEEE  Transactions on Antennas and Propagation , vol. 46, No. 
 BOLIC DISH ANTENNA FOR THE RADAR ALTIMETER !FTER THE ORBITS WERE ACCURATELY DETERMINED  THE ALTIMETERS WERE SWITCHED TO HIGH 
 (4.1) to (4.:1) represent sine-wave carriers upon which the pulse modulation is  imposed. The difference frequency is equal to the doppler frequencyfd. For stationary targets  the <loppler frequency shift/d will be zero; hence Vd;rr will not vary with time and may take on  any constant value from + .'14 to -/14• including zero. 
 Silicon bipolar power transistors have been under de- velopment far longer than their silicon FET equivalents; consequently, many of the earliest solid-state transmitter designs utilized the bipolar devices. However, the silicon power FET is a viable alternative device type for the amplifier de- signer. Unlike bipolar transistors, which are minority carrier devices, FETs are . 
 D. J. Donohue, H-C Ku, D. 
 36, p. 359, footnote 1). 38. 
 3YNCHRONOUS  /RBITS  3UN 
 The optically fed technique results in feed energy spillover around the aperture;  however, these resultant spillover sidelobes can be eliminated by an absorbing cone  between the feed and the array aperture. The absorbing cone is observed in the AN/ MPQ-39 (Figure 9.1 b). However, cooling is also necessary and provided, as observed  by the cooling coils around the absorbing cone. 
 Sensors 2019 ,19, 3073 where vis the linear deformation rate, which is regarded as a constant parameter over each time-adjacent interferometric period, and tdeﬁnes the temporal baseline for the i-th interferogram. 2.2. Rheological Model Based on the Kelvin Model As discussed above, a Linear rheological model can express the complex mechanical properties of the rheological deformation easily and directly. 
 Another important application ofradardesigned forthedetection ofweather echoesisinairborne weather-avoidance radars,whosefunction istoindicate totheaircraft pilotthedangerous stormareastobeavoided./'.. RADAR CLUTTER 499  Radar equation for meteorological echoes.69 " The simple radar equation is  The symbols were defined in Sec. 1.2. 
 As the target moves off axis in either direction, there is a change in relative phase. The amplitudes of the signals in each aperture are the same so that the output of the angle error phase detector is determined by the relative phase only. The phase-detector circuit is adjusted with a 90° phase shift in one channel to give zero output when the target is on axis and an output increasing with increasing angular displacement of the target with a polarity corresponding to the direction of error.3'4 Typical flat-face corporate-fed phased arrays compare the output of halves of . 
 D.: Low-Angle Radar Tracking in the Presence of Multipath, lEEE T/.iins., vol. AES-10, pp.  835-852, November, 1974. 
 In particular, these included measurements with the Skylab radiometer-scatterometer RADSCAT83 and with truck-mounted microwave active spectrometers (MAS)81 by the University of Kansas. Two dif- ferent models were developed based on the same data, one a linear model and one a more complicated formulation. Here we present only the linear model. 
 POLARIZED RADAR THAT RETAINS THE RELATIVE PHASE BETWEEN THE TWO RECEIVED POLARIZATIONS IS A SIGNIFICANT DEPARTURE FROM TRADITIONAL DUAL 
 The ptiase  of tlie rnodulatioii depends on the angle between the target and the rotation axis. The conical-  scan tnodulatiori is extracted from the eclio signal and applied to a servo-control system which  coiitini~ally positions the antenna on the target. [Note that two servos are required because  tl~c tr;\ckirig prot7lctti is two-ditnctisiorial. 
 By M.I Skolnik, 2nd Edition, Tata McGraw Hill.   5. ‘Understanding Radar Systems’ by Simon Kinsley and Shaun Quegan, Scitech Publish ing,  McGraw -Hill. 
 (i. 1). M.. 
 J. W. Maresca, Jr. 
 Ifthe line ofsight isnearly horizontal, strong signals are sometimes observed bydirect specular reflection from vertical surfaces without the benefit ofmirror reflection from’ anintermediate horizontal surface. Special cases oftarget directivity inazimuth arise when, forinstance, large groups ofbuildings have parallel walls. The signals indirections perpendicular tothese walls are often intensified, ascan beseen in Fig. 
 AXIS AND SHOWING THAT THE IMAGE LOCATION  OF THE TOWER TOP IS LOCATED A DISTANCE THE  LAYOVER DISTANCE   D   H(2G COS PSQ  FROM  THE IMAGE LOCATION OF THE TOWER BASE &IGURE  C THEN DEPICTS THE VIEW IN IMAGE  COORDINATES X  Y  4HE IMAGE COORDINATES OF THE TOWER TOP ARE   X   X   D SIN PSQ  Y   Y  
 FREQUENCY 3YNTHESIS $$3  !$ CONVERTERS AND CONTROL INTERFACE MODULES ARE THE FINAL CLASS "USSING PROTOCOLS AND SPEEDS MUST HAVE ADEQUATE RESERVES TO INSURE FAIL 
 2.8a. These curves were derived from data  given by Marcum. The integration loss is shown in Fig. 
 ,UPE 'ERMANY HAS FIVE IDENTICAL 8 
 T., D. E. Barrick, W. 
 91. Konrad. T. 
 16.14 .—R-f locking, r-f addition. (a) R-f locking by transmitter, r-f addition. (b) R-f locking by oscillator, r-f addition. 
 GFO  was designed to replicate as much  as possible the Geosat exact-repeat  mission, in support of operational  requirements for the U.S. Navy. GFO  represents the current state-of-the- art in small dedicated radar altimeter  missions. 
 Breakdown inthe con- nectors limits the peak power toafew kilowatts; the most common use ofsuch cable isintest equipment. Attenuation data are given in Table 11.1. 11.3. 
 Suppose that the horizontal width ofthe antenna aperture has been fixed byother design considerations atthevalue a. The maximum gain possible will beobtained iftheillumination oftheantenna aperture isuniform horizontally, and inthis case itcan beshown that inany plane such asACEF, Fig. 2“2, the gain asafunction ofthe angle @ willbel ()7ra+sin2 — G+=G(~=o)A (-)2“rra+ x Asafunction of8and @then, thepattern iscompletely described by ()CSC28‘in2‘+4 G=GosO (-)2’7ra+ A(8) (9) . 
 Glackin, B. Holt, L. Jones, W. 
   LOBES  BUT AT THE EXPENSE OF A SOMEWHAT BROADER MAINLOBE  A PRICE THAT THE USER IS TYPICALLY WILLING TO PAY -ANY TYPES OF WEIGHTING EXIST )F NO WEIGHTING IS APPLIED  THE 03& IS A SINC   FUNCTION OF THE FORM  SINX X  )N THAT CASE  THE FORMULAS ABOVE FOR 3!2 RESOLUTION .   39.4(%4)# !0%2452% 2!$!2   £Ç° REPRESENT THE DISTANCE FROM THE MAINLOBE PEAK TO THE FIRST NULL .OTE THAT THIS DEFINITION OF  3!2 RESOLUTION IS DIFFERENT FROM THE MORE COMMON DEFINITION OF THE HALF 
 In an attempt to resolve this, some work has been performed to try to better formal - ize marine radar clutter performance tests, including some research performed on behalf  of the UK Maritime and Coastguard Agency.36  This approach was aimed to minimize  any special configuration of the radar under test. It is based on a system that generates  simulated target and clutter waveforms. These are picked up by the antenna of the radar  under test from a nearby transmitting source, typically situated about 100 meters from  the radar antenna. 
 0ROTECTION 33* 3ELF 
 One other method should be mentioned of achieving coherent MTI. If the number of  cycles of the doppler frequency shift contained within the duration of a single pulse is  sufficient, the returned echoes from moving targets may be separated from clutter by suitable  RF or IF filters. This is possible if the doppler frequency shift is at least comparable with or  greater than the spectral width of the transmitted signal. 
 The difference in the phases of  the echoes received from the point target observed by the two antennas is now  ∆φπ ψ λ22 2=nLsin (17.54) We consider the quantity  ∆ ∆ ∆ φ φ φπ λψ ψ ≡ − = − | | |sin sin |2 1 2 12nL (17.55) We assume that h  R and thus y2 ≈ y1 ≈ (y2 + y1)/2 = y . Then, where ∆y  =   |y 2 − y1| , from Figure 17.14,  ∆ ∆ φπ λψ ψπ λψψπ λ≈ = =2 2 2 nL nL h RnLh Rcos coscos (17.56)FIGURE 17.14  InSAR—-vertical antenna separation: Vertical antenna separation enables estimation of the  height of a target above the average ground height or, more generally, terrain height versus location. ( Courtesy  of SciTech Publishing, Inc .)Point Target b  above Ground  Plane Point Target a  on Ground  PlaneLA B RR z h = z cos ψs ψ ψψ ψ2 ψ2 ≈ ψ1 ≈ ψψ1 ∆ψ ch17.indd   31 12/17/07   6:50:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 waveform is a constant-frequency pulse with an offset of fd + a^ (T^ — Tin). A spectrum analysis of this IF signal will yield the relative target range (TR — Tin) information. This frequency offset (exclusive of the target doppler) can be rewrit- ten as B (AT/7), where B is the transmitted waveform bandwidth and AJ is the time separation between the two waveforms. 
 Since the clutter varies inphase aswell as amplitude, itsphase variations areconverted bythedetector, when the reference signal ispresent, into amplitude variations, which unfortunately arenotindependent ofthesize oftheclutter. Itcan beshown, however, that noserious harm results ifthereference signal level iskept somewhat smaller than themaximum amplitude ofthelinear portion ofthereceiver characteristic. The second method ofobtaining uniform output fluctuations depends onthefact that therms phase variation oftheclutter isindependent of thesize oftheclutter. 
 999-RH-35, April. 1969.  hH Special Issr~c or1 iliological Effects of Micrownvcs. 
 Huba, G. Joyce, and J. A. 
 Multiple-reflector systems, typified by the Cassegrain antenna of Fig. 6.3/, of- fer one more degree of flexibility by shaping the primary beam and allowing the feed system to be conveniently located behind the main reflector. The symmet- rical arrangement shown has significant blockage, but offset arrangements can readily be envisioned to accomplish more sophisticated goals. 
 Both difference channels dete rmine the angles in azimuth and elev a- tion.  For the transmitting case (arrows in opposite directions), the power is fed into the su m- mation channel and the difference channels are decoupled and remain without power.  Three parallel receiving channels are re quired for monopulse Radar, which must be synchronized  with one another. 
 Ungated contacts generally represent clutter. Gated con - tacts generally represent targets. Re-thresholding, in this case, successfully  eliminates large numbers of clutter detections while preserving most target  detections. 
 McCue, J. J. G.: Suppression of Range Sidelobes in Bistatic Radars, Proc. 
 T. W. Bristol, “Acoustic surface-wave-device applications,” Microwave J ., vol. 
 506 THERECEIVING SYSTEI-INDICA TORS [SEC. 139 two diagrams indicating clamps ofopposite polarities. They will, of course, close only ifthepotential ofpoint Xisinthespecified direction from li’O,and even when closed they will offer noimpediment topotential changes intheopposite direction. 
 §S PULSE   A     AND  "    -(Z    1UADRIPHASE #ODE2ECTANGULAR  3UBPULSE #ODE 2ADIATED 3PECTRUM  
 •Dictionary update stage: For each column k=1, 2, ..., KinDJ−1, –Deﬁne the group of samples that use this atom, wk={i|1≤i≤N,xk T(i)/negationslash=0} –Compute the overall representation error matrix, Ek,b y Ek=Y−∑ j/negationslash=kdjxj T –Restrict Ekby choosing only the columns corresponding to wk, and obtain ER k. –Apply SVD decomposition ER k=UΔVT. Choose the updated dictionary column /tildewidedkto be the ﬁrst column of U. 
 A digital correlator in a later stage of the receiver completes the matched filter. Filtering Problems Associated with Mixer Spurious Responses. The approx- imation of a matched filter is generally most easily accomplished at some DEVIATION FROM CENTER FREQUENCY PER 6 dB BANDWIDTH (AfXB6) FIG. 
 PERIOD STAG 
 TION MAY BE LACKING  FOR EXAMPLE  DUE TO HEAVY SEA CLUTTER  THE ADDITIONAL INFORMATION  TRANSMITTED ON !)3 CAN BE EXTREMELY USEFUL &OR INSTANCE  A TAR GETS HEADING IS TRANS 
 Radar  Conf ., Alexandria (V A), USA, May 7–12, 2000, pp. 187–192. 151. 
 COMBINING TECHNIQUES IN AIR 
 ( 10.33) or ( 10.34 )] more closely describes the output of the receiver.  The ratio of the density function for signal-plus-noise to that for noise alone is the  likelihood ratio. It may be used to decide whether or not the signal is present. 
 TRAFFIC CONTROL RADARS 0ULSE 
 Ê-- 
 The phased array antenna is a 26 ft by 4.5 ft  elliptically shaped, ultra-low sidelobe array, consisting of 28 slotted waveguides with  over 4000 slots (see Figure 13.45). Mounted atop the aircraft fuselage in a rotating  dome, the S-band antenna scans mechanically over 360 ° in azimuth, and scans elec - tronically in elevation through 28 reciprocal beam-steering phase shifters. In addition,  28 nonreciprocal beam offset phase shifters provide offset of the receive beam from  the transmit beam during elevation scanning to compensate for time delay between  transmit and receive of long-range aircraft returns. 
 Thus, the WSR-74C is a C-band weather radar introduced in 1974. GENERAL BOOKS ON RADAR 1. Skolnik, M. 
 3CHWARZ INEQUALITY F X G X DX F X DX G X DX   \ \ \ \ 
    -ARCH   6 ' (ANSEN AND * 2 7ARD  h$ETECTION PERFORMANCE OF THE CELL AVERAGE LOG#&!2 RECEIVER v  )%%% 4RANS  VOL !%3 
 The  Babs equipment on the aerodrome consists of a small -  transponder (transmitter and receiver), situated at the ©  . TRAVEL BY BEACON 159  end of the runway, and accurately aligned so that the  major beam of transmission is correct for landing con- ditions. The fixed installation is erected for the main runway, and the other runways are usually served by mobile equipment. 
 Other aircraft in ﬂight could be observed at a range of 10 miles and their approximate direction of ﬂight determined. Reliable maximum ranges against a fully-surfaced submarine were 12 miles at 500 ft and 10 miles at 250 ft. The 50 cm equipment was installed in an Anson with a 100 kW transmitter similar to that used in the 1.5 m radar. 
 LINE FIT LINEAR  REGRESSION  BETWEEN CLUTTER CROSS SECTIONS IN DECIBELS AND THE LOG OF THE WIND SPEED OR SOME OTHER PARAMETER  4HIS  OF COURSE   IMPOSES A POWER 
 £Ç°£{  2!$!2 (!.$"//+  3IMILARLY  THE RELATIVE VELOCITY OF POINT " ON THE OPPOSITE SIDE OF THE BEAM IS   VR6 22 $6 $"  ¤ ¦¥³ µ´¤ ¦¥³ µ´  7LL     4HUS  THE RANGE OF RELATIVE VELOCITIES IN THE SCENE IS   $7 7 7VR R R6 $ 
 DELAY ELEMENTS !LL SUBARRAYS ARE STEERED IN THE SAME MANNER 4HE  TOTAL RADIATION PATTERN IS THE PRODUCT OF THE ARRAY FACTOR AND THE ELEMENT FACTOR ! CHANGE  IN FREQUENCY GIVES RISE TO GRATING LOBES RATHER THAN SHIFTS OF THE BEAM POSITION 4HIS CAN BE SEEN FROM &IGURE  4HE SUBARRAY PATTERN IS SHOWN AT THE DESIGN FREQUENCY  F  AND  IS SEEN TO HAVE A NULL AT THE POSITION OF THE GRATING LOBE !S FREQUENCY IS CHANGED BY  C  F   THE PATTERN IS SCANNED )T IS SHOWN DASHED IN A POSITION WHERE IT HAS BEEN SCANNED BY A LITTLE MORE THAN HALF OF ITS BEAMWIDTH 4HIS IS CLEARLY TOO MUCH  FOR THE PRODUCT OF ARRAY AND ELEMENT FACTORS GIVES TWO BEAMS OF EQUAL AMPLITUDE 4HE LOSS IN GAIN AND THE MAGNITUDE OF THE GRATING LOBE ARE FUNCTIONS OF THE FRACTIONAL  SUBARRAY BEAMWIDTH THAT HAS BEEN SCANNED AS A RESULT OF THE CHANGE IN FREQUENCY 4HE RESULTS MAY BE EXPRESSED IN TERMS OF THE BANDWIDTH FACTOR  + REFERRED TO AS THE  SUBARRAY  BROADSIDE BEAMWIDTH  &IGURE  SHOWS THESE VALUES AS FUNCTIONS OF + FOR A SCAN OF n 4HE VALUE PREVIOUSLY USED FOR SCANNING  n WAS +    AND THIS VALUE APPEARS  ACCEPTABLE HERE  WHERE THE RELEVANT BEAMWIDTH IS THE BROADSIDE BEAMWIDTH OF THE SUBARRAY 4HUS  IF THE APERTURE IS SPLIT INTO  . SUBARRAYS IN ONE PLANE  WITH TIME 
 Introduction Ionospheric variations have been studied for earthquake prediction, solar activity analysis, radar image modiﬁcation and geomagnetic storm research [ 1–5]. Among all kinds of ionospheric characteristics, the total electron content (TEC) is one of the most used parameters. For TEC evaluation, widely used instruments include Incoherent Scatter Radar (ISR), ionosonde, and Global Navigation Satellite Systems (GNSS). 
 vol. PS-30, pp. 865–875, June 2002. 
 TACCAR. The MIT Lincoln Laboratory originally developed TACCAR to solve the AMTI radar problem. After many other approaches, it was recognized that if one used the clutter return rather than the transmit pulse to phase-lock the radar to the clutter filter, one could center the clutter in the filter stopband. 
 Lipka, A. Mays, and E. Ornstein, “TRAKX: A dual-frequency tracking  radar,” Microwave J ., vol. 
   PP n  -ARCH   ( - &INN  2 3 *OHNSON  AND 0 : 0EEBLES  h&LUCTUATING TARGET DETECTION IN CLUTTER USING SID 
 02& &IR &ILTERS &),4%2 #OEFFICIENT  #OEFFICIENT  #OEFFICIENT  #OEFFICIENT  #OEFFICIENT   D"  n n n    D"  n n     D"  n     n D"  n     n D"  n   n n D"  n   n  . 
 Aportionoftheradiated energyisintercepted bythetargetandisscattered, someof itinthedirection oftheradar,whereitiscollected bythereceiving antenna. Ifthetargetisin motionwithavelocity Vrrelativetotheradar,thereceived signalwillbeshiftedinfrequency fromthetransmitted frequency 10byanamount±!cJasgivenbyEq.(3.2).Theplussign associated withthedoppler frequency appliesifthedistance between targetandradaris decreasing (closing target),thatis,whenthereceived signalfrequency isgreaterthanthe transmitted signalfrequency. Theminussignappliesifthedistance isincreasing (receding target).Thereceived echosignalatafrequency 10±fdenterstheradarviatheantenna andis heterodyned inthedetector (mixer)withaportionofthetransmitter signal/o toproduce a doppler beatnoteoffrequencyId'ThesignoUdislostinthisprocess. 
 It can also simulta - neously provide the lower data rate tracking of multiple targets similar to that  performed by ADT. Imaging radar . This radar produces a two-dimensional image of a target or a scene,  such as a portion of the surface of the earth and what is on it. 
 foE 1'_•f\fVVV\.f\f\."'<=1~.::.:>~ > Beat-frequency amplifier (al (1) <Il Co 0.. <Il (1) 0:: Frequency (b) Figure3.2(a)SimpleCWradarblockdiagram; (b)response charactcristic ofhcat-frcLJlIcm;y amplifier.. The purpose of the doppler amplifier is to eliminate echoes from stationary targets and to  an~plify the doppler eclio signal to a level where it can operate an indicating device. 
 A suggested conventional value for Ttr is 290 K. Receiver Noise Temperature. The effective input noise temperature of the receiver Te may sometimes be given directly by the manufacturer or the designer. 
 0OINTING !CCURACY  4HE ACCURATE DETERMINATION OF THE DIRECTION OF TARGETS IS  MADE WITH THE MONOPULSE DIFFERENCE PATTERN 4HE ACCURACY OF THE NULL POSITION OF THE  DIFFERENCE PATTERN IS  THEREFORE  OF INTEREST 7ITH QUANTIZED PHASE SHIFTERS  THE POSITION OF THIS NULL CAN BE MOVED WITH A GRANULARITY THAT IS A FUNCTION OF THE BIT SIZE &OLLOWING THE ANALYSIS OF &RANK AND 2UZE   &IGURE  SHOWS AN APERTURE WITH  AN EVEN NUMBER OF ELEMENTS  .  SEPARATED BY DISTANCES  S !LL ELEMENTS ARE EXCITED WITH .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°Îx EQUAL AMPLITUDE AND ANTISYMMETRIC PHASE TO GIVE A DIFFERENCE PATTERN 4HE STEERING  INCREMENT IS SHOWN TO BE   DQP  .0"SCANNED   0 ERIODIC %RRORS 0ERIODIC !MPLITUDE AND 0HASE -ODULATION  "OTH AMPLITUDE AND PHASE QUANTIZA 
 Because the GBVP approach leads  to the analytical expression of the Bragg scattering hypothesis that has dominated the  theory of sea scatter since the late 1960s, a brief explanation of some of the central  ideas is included below. Theories Based on Global Boundary-Value Problems.  General formulations  of the GBVP, though elegant, are of little practical value, and some kind of approxi - mation is necessary to obtain useful quantitative results from them. 
 4. Interpulse noise: Unlike the above three factors, interpulse noise is the noise produced by an RF tube when it is supposed to be completely off; that is, between pulses. Noise generated at this time is of concern because, in almost all radar system configurations, this noise will feed directly into the radar receiver and may either produce false targets or mask real targets. 
 SISTORS ARRANGED IN A  
   NO   !UGUST &)'52%   !2%03 SIGNAL 
    B. 
 The range resolution is obtained with either a conventional short-pulse or pulse-compression  waveform, and resolution in cross range is obtained by synthesizing the effect of a large  antenna aperture. It is used chiefly for mapping of the ground and imaging of stationary  objects on the ground.  Inverse synthetic aperture radar. 
 OF 
 40-45, IEEE Publication  77Cf.11250-0 AES.  136. Sangiolo. 
 For an ideal (lossless), uniformly illuminated aperture of area A operating at a wave- length X, the directive gain is given by G0 = 4-TrA/X2 (6.7) This represents the maximum available gain from an aperture A and implies a perfectly flat phase distribution as well as uniform amplitude. Typical antennas are not uniformly illuminated but have a tapered illumination (maximum in the center of the aperture and less toward the edges) in order to reduce the sidelobes of the pattern. In this case, the directive gain is less than that given by Eq. 
 !IR -ODE 3UITE  3IMILARLY  THE ! 
 If narrowbeamwidthsaretobeachieved, theradarantenna mustbeaphysically largephased array.Aone-degree beamwidth, forexample, requires anaperture ofabout1200mata frequency of15MHz.Sincethetransmitting antenna musthandlehighpower,itismore costlytoobtainthanlargereceiving apertures. InonetypeofOTHradardesign,a(rela­ tively)smalltransmitting antenna withbroadazimuth beamwidth isusedalongwithalarge receiving aperture consisting ofanumber ofnarrowcontiguous beamscovering theangle illuminated bythewidetransmitting beam.Thusthecomplexity ofalargetransmitting antenna istradedforanumber ofparallel receiving channels. Itisalsopossible toutilizea common aperture forbothtransmit andreceive,withequaltransmit andreceivebeamwidths. 
 UP AND .ORTH 
 LEVEL $"& $"& CAN PROVIDE MORE EFFICIENT TIME 
 169. Sensors 2018 ,18, 3750 Figure 11. InISAR imaging results of Backhoe with complete data. 
 25 28. 1977. IFF {London) Conf. 
 HEATING 4HE !&# C AN BE APPLIED TO THE  MAGNETRON ITSELF TO KEEP IT OPERATING ON ITS ASSIGNED FREQUENCY  WITHIN THE LIMITS OF THE ACCURACY OF THE TUNING MECHANISM ! MAGNETRON CAN BE MECHANICALLY CHANGED IN FREQUENCY OVER A  TO  FREQUENCY  RANGE AND  IN SOME CASES  AS MUCH AS  2APID MECHANICAL TUNING CAN BE ACHIEVED WITH A SLOTTED DISK SUSPENDED ABOVE THE ANODE CAVITIES 7HEN ROTATED  IT ALTERNATELY PROVIDES INDUCTIVE AND CAPACITIVE LOADING OF THE CAVITIES TO RAISE AND LOWER THE FRE 
 It is also useful as a sanity check ; because at these limits, all bistatic  radar equations must reduce to an equivalent monostatic equation. 23.3 BISTATIC RADAR EQUATION Benchmark Range Concept.  Unlike a monostatic radar, the range performance  of a bistatic radar is a function of the geometry, specifically the baseline range L and  an antenna look angle, either qT or qR. 
 H., and S. T. Cost: The Bistatic Echo Area of Terrain of 10 GHz, WESCON 1968, sess. 
 I>. C.: Radar Detection in Log-Normal Clutter, lEEE 1975 l~~terttatio~tal Radar Cot~fi~re~tcr,  Arlinptoti. Va.. 
 This is a popular frequency band for military weapon control (tracking) radar and for civil applications. Shipboard navigation and piloting, weather avoidance, doppler navigation, and the police speed meter are all found at X band. Radars at this frequency are generally of con- venient size and are thus of interest for applications where mobility and light weight are important and long range is not. 
 109.Brown,1. S.,andK.E.McKee: WindLoadsonAntenna Systems, Microwave J.,vol.7,pp.41-46, September, 1964. 110.Thorn,H.:Distribution ofExtreme WindsintheUnitedStates,ASCETrans.,vol.126,pI.II,paper 3191,1961. 
 It should be expected that with a book in print as long as the Radar Handbook  has been, not all chapter authors from the previous editions would be available to do the third edition. Many of the previous authors have retired or are no longer with us.  Sixteen of the twenty-six chapters  in this edition have authors or coauthors who were not involved in the previous editions. 
 The 1Chap 6,Vol. 17;Chap 24,Vol. 19,Chaps. 
 Navy's t!-3('  (Fig. 7.30) or the 30-ft-diameter radome of AWACS. Tlie E-2C radome weighs just over  2000 1b. 
 Thanks to the mission design, however,  Magellan  image quality is surprisingly consistent, pole to pole. The reasons provide  an important object lesson. Since the Magellan radar was operated in burst mode, it was convenient (as well  as necessary) prior to each burst to set the mode parameters, which, in general, varied  from burst to burst. 
 36–45, 1989. 173 Touzi et al., “Polarimetric discriminators for SAR images,” IEEE Trans. on Geosc. 
 Griffiths, “A four-element VHF adaptive array processor,” Proc. 2 nd IEE Int. Conf. 
 Another radar area that has seen much development is that of the electronically steered  phased-array antenna. In the first edition, the radar antenna was the subject or a single  chapter. In this edition, one chapter covers the conventional radar antenna (Chap. 
 4.6.  74. Nathanson, F. 
 This permits a given scan angle to be obtained with a  smaller frequency change. Denote by the integer m the n':!!Jlber of 2n radians added. By equating  this phase difference to the phase shift obtained from a line of length/, as given by Eq. 
 Further comments on Table 4.1 are given below. Voltage. Voltage affects the size and cost of the HVPS and modulator as well as x-ray severity. 
 In practice, the joints between the "linear" segments are not abrupt, and the best fit to the log- arithmic curve may have less than the theoretical error. Logarithmic detectors and amplifiers are frequently designed with adjustments in each stage. This allows for adjustment of the slope and/or length of the seg- ment for a better fit. 
 Signal-to-noise ratio can be measured quite  easily on a radar set, for it can be done with an inch tape.  When we have switched on the set we notice that the  steady noise causes a layer of grass on the tube, and  although it will appear to be shimmering slightly, we  tah, fo within about an eighth of an inch, make a prac-  . THE ECHO COMES HOME 47  tical measurement of this with a straight-edge. 
 W., Jr., and K. M. Siegel: "Methods of Radar Cross-Section Analysis," Academic Press,  Inc., New York, 1968, chap. 
 The effect can be offset by yaw-steering the spacecraft so that the  antenna’s boresight is always directed toward zero doppler. This orients the vertical  plane of the azimuth boresight to be orthogonal to the nadir track on the surface, rather  than to the orbit plane. Whereas SAR data from both arrangements can be processed  into satisfactory imagery, more demanding applications such as radar interferometry  are better served by yaw-steered systems. 
 Bomber Command and U.S. [Xth Air Force  were made in Britain, and all the miniature centimetric  transmitters and the special Oboe transmitting valves  needed by the British and American forces were made  in-the United States. With this sort of apparatus jam-  ming is very difficult, and it appears from numerous tests  that the accuracy of the range measurement is of the  order of yards, and is substantially independent of range. 
 % SERIES  SINCE THEY  ARE BOTH OUTGROWTHS OF A BILATERAL DEVELOPMENT PROGRAM BASED ON THE ARCHITECTURE OF THE 0RIRODA 3 BAND RADAR 4HE (* 
 Woodhouse and D. H. Hoekman, “Determining land-surface parameters from the  ERS wind scatterometer,” IEEE Transactions on Geoscience and Remote Sensing , vol. 
 M. Rader, “VLSI systolic array for adaptive nulling,” IEEE Signal Processing Magazine ,   vol. 13, no. 
 Each 4000 kg  spacecraft was a cylinder 5 m in length. The synthetic aperture radar antenna was a  6 × 1.4 meter parabolic cylinder reflector, powered by an 80-watt traveling wave tube  amplifier. Rather than pulse or chirp modulation, Venera  used a continuous transmission  modulated by a coded sequence of 180 ° phase shifts. 
 Aradaroperating atLhand (1.3GHz),forexample, mightexperience about34dBlessprecipitation cluttcr..than aradarat Xband(9GHz).Thuswhenprecipitation isofconcern, thelowerfrequencies aretobe preferred. Atthehighermicrowave frequencies, precipitation cluttercanhereduced bymeansor highresolution inrangeandinangle.Sincerainisrelatively uniform, thestatistics ofthe backscatter aredescribed bytheRayleigh probability densityfunction, evenwhentheradaris ofhighresolution. Therefore theproblem ofnon-Rayleigh statistics withitsdeleterious effect onthefalse-alarm probability asoccurswithhigh-resolution radarviewing seaclutterand landclutter(Secs.13.3and13.5),doesnotusuallyoccurwithprecipitation clutter. 
 11.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 Figure 11.23. The transmitter portion of the T/R module contains seven silicon bipo - lar power transistors, operated Class-C from a 31 V dc power supply. The transmit  amplifier chain consists of a predriver transistor feeding two driver transistors, in turn  feeding four final transistors, i.e., a 1-2-4 configuration. 
 COMBINED DESIGN IS THE hSOLID 
 4, pt. I, pp. 39-47, 1956. 
 VERTER ADDITIVE THERMAL NOISE IS INDEPENDENT OF OUTPUT SIGNAL FREQUENCY AND PRODUCES BOTH PHASE AND AMPLITUDE NOISE COMPONENTS &REQUENCY -ULTIPLIERS  &REQUENCY MULTIPLICATION ALLOWS SIGNALS TO BE INCREASED  IN BOTH FREQUENCY AND BANDWIDTH &REQUENCY MULTIPLICATION IS FREQUENTLY USED IN GEN 
 According to SAR imaging theory, the high resolution along the ﬂight direction is realized by synthesizing a large virtual aperture within the synthetic aperture time. However, the 326. Sensors 2019 ,19, 1529 best resolution along the ﬂight direction is restricted by its actual antenna aperture length, which is half of the antenna aperture. 
 Substituting Eq. (14.2) into (14.1) gives the cross-range resolution as , +- . 2%  3  The beamwidth of a synthetic aperture antenna of effective length L, is similarly  The factor 2 appears in the denominator because of the two-way propagation path from the  'irltenna "element" to the target and back as compared with the one-way path of a conven-  tional antenna. 
      6n n     
 Effect ofStorage onRadar Performance.-How istheintegra- tion process, oritsequivalent, actually carried outinaradar set? The earliest and simplest radar indicator istheA-scope, thehorizontal range sweep with vertical deflection bythe signal. Usually the screen ofthe cathode-ray tube does not give apersistent glow but the picture decays immediately. Itisdithcult toseeany integrating orstorage mechanism here, and indeed there isnone. 
 Evans and G. H. Pettengill, “The scattering behavior of the moon at wavelengths of 3.6, 68,  and 784 centimeters,” J. 
 Such an array, which conforms to the geometry  of a nonplanar surface, is called a conformal array.  In principle, the elements of an array located on any nonplanar surface can be made to  radiate a beam in some given direction by applying the proper phase, amplitude, and polariza-  tion at each element. In practice, however, it is difficult to control the beamshape and obtain  low sidelobes from an arbitrary surface, especially if the beam is electronically scanned. 
 May, 1959.  50. Glegg. 
 Atrue{Jogarithmic characteristic cannotbemaintained downtozeroinputsince I'.'UI--4-00as"in--4O.I\tsomepointthereceivercharacteristic mustdeviatefromlogarithmic andgothrough theorigin.Thepractical logarithmic receiver willhavealawgivenby ,'out=alog(I+hl'in)'Thereceivercharacteristic islinearatlowsignallevelsandlogarithmic atlargesignals.Thisiscalledalin-logreceiver.Thelogarithmic characteristic mustbemain­ tainedtoabout20dBbelowthermsnoiselevel.88Avariation ofthelog-FTC isthelog-CFAR receiverinwhichtheorderoftoresolution cellscontaining clutterareaveraged byanarrow­ handvideofilterwithasymmetrical impulseresponse.90 Although thelogarithmic receiver actssimilarly toanautomatic STC,itdoesnot suppress properly, asdoesSTC,thenearbyclutterechoeswhichenterviathesidelobes. STC turnsdownthegainatcloseranges,therebyreducing sidelobe cluttersignals.Clutterlarge enoughtoappearinthesidelobes ofalogarithmic receivermightnotbesuppressed andmay confusetheradardisplay.ForthisreasonSTCandlogarithmic receivers aresometimes used together. TheSTCactionshouldbeintheRFportionofthereceiver ratherthaninthe logarithmic amplifier.. 
 THE 
 Corlsider a CW radar radiating a single-frequency sine wave of  the form sir1 2?/;, t. (The amplitude of tile signal is taken to be unity since it does not influence  tllc rcsr~lt.) l'lic sig~lal travels to tllc target at a range R and returns to the radar after a time  'I' = 2R/(., wl~ere (. is tile velocity of propagation. 
 Geophys. Res. , vol. 
 35. J. W. 
 98. J. O. 
  %XCITER!-  
 The  two overlapping antenna beams may be generated with a single reflector or with a lens  antenna illuminated by two adjacent feeds. (A cluster of four feeds may be used if both  elevation- and azimuth-error signals are wanted.) The sum of the two antenna patterns of  Fig. 5.7a is shown in Fig. 
 TION SIGNAL  4HE SIGNAL RECEIVED IS COMPARED  TO A STORED REFERENCE OBTAINED DURING FACTORY TESTS /NLY ONE ELEMENT TRANSMITS AT A GIVEN TIME  AND THIS PROCEDURE IS REPEATED UNTIL ALL THE ELEMENTS ARE MEASURED #ALIBRATION USING MUTUAL COUPLING CAN BE INTERSPERSED WITH NOR 
 Frequency [GHz]  σ [m2]  0,41 0,03 - 2  1,12 0,1 - 1  2,89 0,15 - 1  4,8 1,37 - 1,9  9,4 0,5 - 1,2  35 1-10  11.8 Reduction of the Radar Backscattering Cross - Section   The dream of ships and airplanes invisible to Radar is as old as Radar tec hnology itself, known  as stealth technology.  Since it is known that one can locate objects with electromagnetic  waves, especially in military applications, possibilities to reduce the Radar backscattering cross- section have been sought.  Earlier even alch emy was looked to for a solution. 
 . Radar System Engineering  Chapter 12 – Selected Radar Applications  156        Figure 13.25  ACC on MMIC (Layout from Infineon).   13.3.10  Problem Areas   Despite the recognized effectiveness of Radar sensors in street traffic it may not be misco n- ceived that there exist certain problems. 
 SCAN WOULD NORMALLY HAVE TIME 
 The specular point is where  the surface normal points toward the radar. ch14.indd   21 12/17/07   2:47:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Iterate the receiver filter design to  reduce aliasing at a minimal cost in pulse compression perfor mance.  Finally any such design needs to be evaluated relative to implementation tolerances and v aria- tions in transmitter distortion versus frequency, or from module to module, in order to verify  the practicality of the design.   References:   [1] Klauder, J.R., et al, "The Theory and Design of Chirp Radars", Bell System  Technical Jouma/,  Vol.XXXlX, No.4,  pp.745- 809, July 1960. 
 ~-1~------_._-- 0.01 Clutterspectral width!radarprf140 120 aJ100 "0 080U -2 c I1lE60-I1l::-ea..§ 40 20_.-.------- 0 0.001 Figure4.25Improvement factorforanN-pulsedelay-line canceler withoptimum weights(solidcurves) andbinomial weights(dashedcurves),asafunctionoftheclutterspectralwidth.(AleerAndrews.31.32). 5  416  '- ave.  3,7  0 01  (:lutl~r speclrol widtti/rodor prf  (11)  5  ove. 
 Forthemagnctron whoseRiekediagram isshowninFig.6.7,thepulling figureisapproximately 4 MIll.Thepullingfiguresofcoaxialmagnctrons arelowerbyafactor of.1to5thanthoseofconventional magnetrons. Tuning.Thefrequcncy ofaconventional magnetron canbechanged bymechanically inserting atuningclement, suchasarod.intotheholesofthehole-and-slot resonators tochangethe inductancc ofthercsonant circuit. 1\tllncrthatconsistsofaseriesofrodsinserted intoeach cavityresonator soastoaltcrtheinductance iscalledacrown-ol-thorns tuner,orasprocket tllllcr.Theamount ofmechanical motionofthetuningelement neednotbelarge(perhaps a fraction ofaninchatLband)totunethefrequency overa 5to10percentfrequency range.A frcqucncy changeinaconvcntional magnetron canalsobeobtained withachangeincapacity. 
 TO 
 Taylor, S. A., and J. L. 
 BOARD  3%,%.% SPACECRAFT v IN 0ROCEEDINGS  TH #/30!2 !SSEMBLY  0ARIS  &RANCE  PP     % )M  %  3 , $URDEN  3 4ANELLI  AND + 0AK  h%ARLY RESULTS ON CLOUD PROFILING RADAR POST 
  FIGHTER AIRCRAFT AT     AND  -(Z  COMPUTED FOR (( POLAR 
 4(% 
 Materials include single-ply neoprene­ coated tcrylene or nylon fabric, Hypalon-coated Dacron, and Teflon-coated fiberglass.  lnnation pressures are in the vicinity of0.5 lb/in2 gauge. Air-supported radomes can be folded  into a small package which make them suitable for transportable radars requiring mobility  and quick erection times. 
 For  phased arrays, the amplitude of each element may be controlled individually, and  therefore, good sidelobe control can be achieved. The process of designing a low- sidelobe antenna can be considered in two parts: 1. Choose the correct illumination function to achieve the desired design (error-free)  sidelobes. 
  F  3IGNAL FREQUENCY SHIFT   XT4 \ 4\8  F4  4IME SCALING  XT YT     8  F   9  F   4IME DOMAIN CONVOLUTION  XT YT  8F 9F     4IME DOMAIN MULTIPLICATION REP4XT;  = \\ ;  =48 F4COMB7OODWARDS REPETITION OPERATOR COMB4XT;  =\\ ;  =48 F4REP7OODWARDS COMB OPERATOR  8T  XnF    4IME 
 Power outputs can beestimated byassuming anefficiency of40percent. TARJ.E10,2.—INFuT CUAEACTERISITCS OFMICMW.*VE MAGN ETROM I I 1 Tube No. IInput pulse IPulse voltage, 1Input impedance, power, kw kv ohms I I I 4J60 2 15 1125 2J38 25 5 1000 2J32 250 15 900 4J31 2500 30 360 HP1OV 6000 50 415 Byvarying themagnetic field inwhich themagnetron operates, any given design can bemade tooperate satisfactorily over arange ofpulse voltage ofroughly 50percent. 
 SURFACE WINDS COVER n MS WITH ACCURACY  o  MS AND  o n  4HE RADAR OPERATES AT  '(Z   RADIATING  MS LINEAR FREQUENCY 
 The tube VI serves the same function asbefore and Vjacts asad-crestorer. The presence oftheresistor RIincreases therequirement foralow-impedance source. Ifthewaveform source has high impedance, itisnecessary tointro- duce acathode follower asshown inFig. 
 ANGLE CLUTTER FOR ORTHOGONAL WIND DIRECTIONS  3C IS A CONVENTIONAL SHADOWING FUNCTION 34 IS A THRESHOLD 
 If the correlator operates in its linear  region, the echo plus its interference convolved with the reference plus its interference  produces the desired echo with full matched-filter gain plus interference with gain  reduced by mismatch. These signals add vectorially to modify the pattern-propagation  factor. However, if the correlator operates in its nonlinear region, which can frequently  happen, cross-products are generated, which reduce the echo’s matched-filter gain. 
 Also great progress has been made with indoor near-field antenna ranges,16 where computer-controlled precision two-dimensional radia- tion patterns are derived at multiple frequencies, and with scanning. Phased arrays are very expensive. As technology advances, costs are re- duced, particularly in the areas of phase shifters and drivers. 
 -   3 , *OHNSTON  h7ORLD 7AR )) %##- HISTORY v SUPPL TO  )%%% )NT 2ADAR #ONF 2EC  -AY n     PP n    ! % (OFFMANN 
 [ CrossRef ] 17. Long, T.; Lu, Z.; Ding, Z.; Liu, L. A DBS Doppler Centroid Estimation Algorithm Based on Entropy Minimization. 
 PLE  IF OPERATING AT AN AVERAGE 2& FREQUENCY OF  -(Z  AT AN AVERAGE 02& OF  (Z AMBIGUOUS VELOCITY OF  KNOTS   AND COVERING A VELOCITY RANGE OF INTEREST OF o KNOTS  THERE ARE APPROXIMATELY  DOPPLER AMBIGUITIES TO COVER 5SING THE  FACTORS OF n    n    AS USED IN 02& STAGGER SELECTION  THE  INTERPULSE PERIODS OF THE  FOUR DIFFERENT 02&S WOULD BE IN THE RATIO OF        4HE AVERAGE OF THESE RATIOS IS  4HE 02&S ARE CALCULATED AS q  q  q  AND q 4HE 02&S WOULD BE ABOUT       AND  (Z Ó°£ÇÊ  " - 
 Curve A is the sum of all effects and is representative  of conical-scan and sequential-lobing tracking radars. Curve B does not include the amplitude  fluctuations and is therefore representative of monopulse radars. In Fig. 
     ' * &RAZER AND  3 * !NDERSON  h7IGNER 
 TheIllonostatic radariswellsuitedtovolumetric coverage. Ifthebistaticradarwereto provide volumetric coverage withdirective antenna beams.thetransmitting andreceiving heamswouldhavetohescanned insynchronism. Ifthereceiving beamisalwaystoobservethe volumeofspaceilluminated hythetransmitted pulsepacket.thereceiving beammusthe scanned rapidly. 
 As a technique for finding target height, digital beamforming involves placing a receiver on each element of a vertical array of elements, or rows of elements. By digitally weighting and linearly combining the analog-to-digital (A/D) converted receiver outputs, a stack of receive beams or a single scanning receive beam in elevation can be generated. In this form, a digital beamforming radar is a special case of a stacked-beam radar, implemented in a technology that offers several advantages over conventional stacked-beam tech- nology. 
 RF gain is typically required to provide a sufficient drive  level to the transmitter or phased array antenna. Almost all modern radar systems use digital signal processing to perform a variety  of functions, including pulse compression and the discrimination of desired targets from  interference on the basis of velocity or the change in phase from one pulse to the next.  Previously, pulse compression was performed using analog processing with dispersive  delay lines, typically surface acoustic-wave (SAW) devices. 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 Centimeter-scale range accuracy is supported in the oceanographic application  by averaging over the range response of many returns. The range resolution of each  return waveform is typically on the order of 0.5 meters. 
 SCATTER QUADRANT  A   n   &OR OTHER ASPECT ANGLES AND TARGETS WITH COMPLEX SHADOW APERTURES  CALCULATION OF THE  FORWARD 
 THE 
 This is a weather observation radar that employs the dop - pler frequency shift caused by moving weather effects to determine the wind; the  wind shear (when the wind blows in different directions), which can indicate a  dangerous weather condition such as a tornado or a downburst of wind; as well as  other meteorological effects. Target recognition . In some cases, it might be important to recognize the type of target  being observed by radar (e.g., an automobile rather than a bird), or to recognize the par - ticular type of target ( an automobile rather than a truck, or a starling rather than a spar - row), or to recognize one class of target from another (a cruise ship rather than a tanker). 
 What the radar can do against DECM is discussed later; see Section 24.1 1. In the deployment of ECM, several classes can be singled out.3 In the stand-off  jammer  (SOJ) case, the jamming platform remains close to but outside the lethal range  of enemy weapon systems and jams these systems to protect the attacking vehicles.  Stand-off ECM systems employ high-power noise jamming that must penetrate through  the radar antenna receiving sidelobes at long ranges. 
 -" 1/"  )N THIS SECTION  WE DISCUSS 3!2 RESOLUTION IN MORE DETAIL "Y hRESOLUTION v IN KEEPING WITH  COMMON USAGE  WE MEAN THE PRECISION TO WHICH WE CAN MEASURE THE LOCATION OF A POINT  TARGET AND NOT NECESSARILY THE ABILITY TO RESOLVE TWO POINT TARGETS &OR A DISCUSSION OF THIS ISSUE  SEE 7OLFE AND :ISSIS   (OW WE DO THIS WILL BE DISCUSSED IN MORE DETAIL BELOW 3INCE FINE RANGE RESOLUTION IS TYPICALLY ACHIEVED WITH A SINGLE PULSE  THE CORRE 
 4IME 
 124. Krnetrn. J. 
 TARY DISPLAYS TO AUTOMATIC ALGORITHMS AND MODERN MULTIDIMENSIONAL DISPLAYS TO ASSIST HUMAN INTERPRETATION %XPERT SYSTEM APPROACHES   THAT ATTEMPT TO REPRODUCE HUMAN  INTERPRETIVE LOGICAL PROCESSES HAVE BEEN EMPLOYED EFFECTIVELY 4HE DEGREE TO WHICH AUTOMATION CAN BE APPLIED IS EVIDENT IN THE .EXRAD RADAR SYSTEM DESIGN THAT PRODUCES THE AUTOMATED METEOROLOGICAL PRODUCTS SHOWN IN 4ABLE  4!",%  0ARTIAL ,IST OF .EXRAD !UTOMATED 0RODUCTS "ASE RADAR REFLECTIVITY ALL RANGES  EACH SCAN  "ASE RADIAL VELOCITY"ASE SPECTRUM WIDTH#OMPOSITE MAXIMUM AT ALL HEIGHTS  REFLECTIVITY0RECIPITATION ECHO TOPS3EVERE WEATHER PROBABILITY6ELOCITY !ZIMUTH $ISPLAY 6!$  7IND 0ROFILE3TORM RELATIVE MEAN RADIAL VELOCITY6ERTICAL INTEGRATED LIQUID3TORM TRACKING INFORMATION(AIL POTENTIAL-ESOCYCLONE AND 4ORNADO 6ORTEX 3IGNATURE3URFACE RAINFALL ACCUMULATION  HR   HR  TOTAL STORM 2ADAR %CHO #LASSIFIER. £°ÓÈ  2!$!2 (!.$"//+  0RECIPITATION  -EASUREMENT  !MONG THE MORE IMPORTANT PARAMETERS TO BE  MEASURED IS RAINFALL  HAVING SIGNIFICANCE TO A NUMBER OF WATER RESOURCE MANAGEMENT  PROBLEMS RELATED TO AGRICULTURE  FRESH 
 94.Dunbar, A.S.:Calculation ofDoubly Curved Rellectors forShapedBeams,Proc.IRE,vol.36, pp.1289-1296, October, 1948. 95.Carberry, T.F.:Analysis Theory fortheShaped- BeamDoubly Curved Retlector Antenna, lEEE Trans.,vol.AP-17,pp.131-138, March, 1969. 96.Brunner, A.:Possibilities ofDimensioning Doubly Curved Rel1ectors forAzimuth-Search Radar Antennas, IEEETrans.,vol.AP-19,pp.52-57,January, 1971. 
 TERM STABILITY ,ONG 
 R. C., arid R. M. 
 If -30 dB is used for the effective scattering coefficient and a resolution cell is considered to be a square 10 nmi on a side, the surface area A is 85 dBsm and the RCS is 85 - 30 = 55 dBsm. A 12 dB path enhancement will be effective owing to constructive multipath addition, which will increase the resolution cell effective RCS to 67 dBsm. The receiver and processor must be able to handle both the high-level signal due to this large RCS and those much smaller signals due to targets. 
 However, this may not always be true. Propeller-driven aircraft produce  modulation components at the blade frequency and harmonics thereof and can cause a sub­ stantial increase in the spectral energy density at certain frequencies. It has been found ex per­ imentally that the tracking accuracy of radars operating with pulse repetition frequencies from  1000 to 4000 Hz and a lobing or scan rate one-quarter of the prf are not limited by echo  amplitude fluctuations. 
 OFF INTERFERENCE SOURCES  WHICH ARE LOCATED ARBITRARILY WITH RESPECT TO THE SURVEILLANCE REGION EG  A GROUND 
 The other terms produce spurious products, which represent an unwanted ability to convert off-frequency signals to the IF of the re- ceiver. The efficiency of conversion of these unwanted frequencies, except for the image frequency, is sufficiently poor that the system noise temperature is not signif- icantly degraded, but the mixer is vulnerable to strong out-of-band interference. The best radar receiver is one with the narrowest RF instantaneous bandwidth commen- surate with the radiated spectrum and hardware limitations, and with good frequency and impulse responses. 
 NICAL AND TEST STANDARDS BASED ON THE )-/ RADAR PERFORMANCE STANDARDS )%# STANDARDS ALSO UNDERGO REGULAR REVISION !N AVERAGE RADAR INSTALLATION HAS A LIFE NORMALLY EXCEED 
 BEAM SYSTEMS ARE ROUTINELY USED TO OBTAIN CONTINUOUS PROFILES OF HORIZONTAL WINDS  WHEREAS SPACED 
 - Ê " - 
    6ICKSBURG  -3    , + 7U  2 + -OORE  2 :OUGHI  & 4 5LABY  AND ! !FIFI  h0RELIMINARY RESULTS ON THE DETER 
 When those leaves were absent, the signals scattered from the soil and lower parts  of the plant were about equal to each other and were much larger than when leaves  were present. FIGURE   16. 28 Boundaries of measured radar data: ( a) horizontal polar - ization and ( b) vertical polarization ( Courtesy of I. 
 POWER SYSTEMS REMAIN USEFUL FOR DYNAMIC TESTING OF TARGETS FLYING OR SAILING PAST THEM ON DYNAMIC TEST RANGES 3TEPPED 
 DETECTED OUTPUTS OF THE TWO CHANNELS  IDEALLY  IDENTICAL EXCEPT FOR THE ANTENNA PATTERNS  ARE COMPARED 4HE COMPARISON IS MADE AT EACH RANGE BIN FOR EACH PULSE RECEIVED AND PROCESSED BY THE TWO PARALLEL CHANNELS 4HUS  THE 3," DECIDES WHETHER OR NOT TO BLANK THE MAIN CHANNEL ON A SINGLE 
 10.7 Waveform limits for a SAW device. for a linear-FM waveform with a BT as low as 15. The dynamic range is limited to under 80 dB by nonlinearities in the crystal material. 
 \K 
 Trunk and  J.D. Wilson80 © IEEE 1987 ) ch07.indd   52 12/17/07   2:15:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The transmitter power is 200 mW and the antenna is a  snlall paraboloid with crossed feeds to make the polarizations of the transmitted and received  CWANDFREQUENCY-MODULATED RADAR97 fromthemethods described inSec.11..\.IIcanbeshownthatthetheoretical rmsrangeerroris c()R=.....--...-.-- 4rr~1(2E/N0)112(3.24) ,,"ereE=energycontained inreceived signalandNo=noisepowerperhertzofbandwidth. II,hisiscompared withtherillsrangeerrortheoretically possible withthelinearFMpulse­ c(npression waveform whosespectrum occupies thesamebandwidth ~r.theerrorobtained wIththetwo-frequency CWwaveform islessbythefactor0.29. Fquation (3.24)indicates thatthegreatertheseparation ~rbetween thetwofrequencies, thelesswillbethermserror.However, thefrequency difference mustnotbetoolargeif unambiguous measurements arctobemade.Theselection of~rrepresents acompromise between therequirements ofaccuracy andambiguity. 
 TRUM SPREAD OUT TO A FEW HUNDRED (Z  DEPENDING ON THE TYPE OF AIRCRAFT 4HE RMS NOISE DENSITY IS TYPICALLY A FEW PERCENT OF MODULATION PER (Z 4HE PERIODIC MODULATION APPEARING AS SPIKES IN THE &IGURE  SPECTRUM ARE  CAUSED BY RAPIDLY ROTATING PARTS OF AN AIRCRAFT  SUCH AS THE PROPELLERS !S THE ECHO FROM A PROPELLER BLADE CHANGES WITH ASPECT WHEN IT ROTATES  A PERIODIC MODULATION  &)'52%     4YPICAL AMPLITUDE SPECTRAL VOLTAGE DISTRIBUTION SHOWING THE PROPELLER MODULATION MEASURED  ON A PROPELLER 
 #OVERED 'ROUND 4HE FIGURE IS ONLY FOR VERTICAL POLARIZATION BECAUSE RESULTS ARE SO SIMILAR FOR  VERTICAL AND HORIZONTAL 5LABY DEVELOPED A DIFFERENT  MORE COMPLEX MODEL FROM THE +ANSAS VEGETATION  DATA 4HIS MODEL FITS CURVES RATHER THAN STRAIGHT LINES TO THE MEASURED DATA &OR MOST  PURPOSES  THE STRAIGHT 
 Ê,,9Ê / 
 !  SATELLITE SCATTEROMETER INSTRUMENT EVALUATION v  )%%% *OURNAL OF /CEANIC %NGINEERING   VOL /% 
 That is relatively easy for the receiver,  which only needs to have two channels that capture simultaneously the phase and  amplitude of two orthogonal polarizations of the backscattered field. On the other  hand, only one polarization can be transmitted at a time. Illuminating the scene with  two polarizations requires the transmitter to be toggled between orthogonal polariza - tion states. 
 TRACK  3!2 INTERFEROMETRY ! SIGNAL 
 L.: Fvaluation of Track-While-Scan Computer Logics. chap. 29 of "Radar  Techniques for Detection. 
 D. L.. and F. 
 ERED CAREFULLY BEFORE APPLICATION OF  A PARTICULAR PROCESSING SCHEME )DEALLY THE SIGNAL  APPLIED TO THE ANTENNA SHOULD BE A $IRAC FUNCTION BUT PRACTICALLY IT IS MORE LIKE A  SKEWED GAUSSIAN IMPULSE OF DEFINED TIME DURATION -OST ANTENNAS USED IN SURFACE PENETRATING APPLICATIONS HAVE A LIMITED LOW FREQUENCY RESPONSE AND TEND TO ACT AS HIGH 
 74. Gunn, K. L. 
 A rotating directional antenna could be used for direction finding (DF); however, an interferometric system with more than one antenna is preferred because the probability of interception is higher than with the system having only one antenna. The carrier frequency is the next most important pulse parameter for deinterleaving. A common method of frequency measurement is to use a scan- ning superheterodyne receiver that has the advantage of high sensitivity and good frequency resolution.4 Unfortunately, this type of receiver has a poor probability of intercept for the same reasons as the rotating bearing measurement system. 
 The targets can be either smooth or complex structures and, from the application of Babinet's principle, can be totally absorbing.37'91 For (3 < 180°, the forward-scatter RCS rolls off from o>. The rolloff is approxi- mated by treating the shadow area A as a uniformly illuminated antenna aperture. The radiation pattern of this shadow aperture is equal to the forward-scatter RCS rolloff when (TT - p) is substituted for the angle off the aperture normal. 
   4S    S FOR TARGETS WITH ESTIMATED SPEED LESS THAN  MS %VEN THOUGH THE TARGET MAY ACCELERATE OR MANEUVER  FOR THE SAKE OF SIMPLICITY  THE  SAMPLING PERIOD IS SELECTED ONLY ON THE BASIS OF THE TARGET ESTIMATED SPEED 3ELECTION OF THE $ETECTION 4HRESHOLD  4HE PRESENCE OF A JAMMING SIGNAL CAN  INCREASE THE NUMBER OF FALSE ALARMS AND WRONG PLOT 
 However, TUNNETT (tunnel injection transit time) devices and BARITT (barrier injection transit time) devices are also used. When an extremely short gate length is used, a MESFET con- struction can be employed at these frequencies, but fundamental limitations on charge carrier velocities and processing tolerances on physically short gate lengths limit the practical operation of MESFET oscillators to below 50 GHz. IMPATT diodes have been made from silicon, gallium arsenide (GaAs), orGate Metal Ohmic Contact, n-f- Implant Drain Metal Source Metal Plated Metal, Source Air Bridge Plated Metal, Backside Via Holes Semi-Insulating GaAsVia HoleN-Type Channel Via Hole . 
  ,  4WO /VALS  2-  2-^O 2- ;2-,= ^O 2- ;2-,= ,  
 CUSSED !DVANCES IN DIGITAL SIGNAL 
 W.  Sutton.  ‘There are peacetime applications to many radar  devices conceived during war, notably H2S, Gee, Oboe,  and Rebecca. 
  RADAR  THIS SYSTEM IMPLEMENTS FREQUENCY 
 Another issue is the choice of transmit polarization. Nearly all operational skywave  radars radiate with vertical polarization, based on the ease of achieving good verti - cal coverage at moderate cost by means of the widely used log-periodic broadband  antenna. The large curtain arrays of the former Soviet radars used horizontal dipole  elements whereas the USAF AN/APS-118 used inclined dipoles to adapt to ground  conditions. 
 Hertz showed that radio waves could be reflected L  ,I  by metallic and dielectric bodies. It is interesting to note that although Hertz's experiments  were performed with relatively short wavelength radiation (66 cm), later work in radio engin-  eering was almost entirely at longer wavelengths. The shorter wavelengths were not actively  used to any great extent until the late thirties. 
 Ifj,>l/(r m, current in. SEC. 10.11] MISCELLANEOUS COMPONENTS 383 theinductance does notreach zero atthetime offiring, and “straight line” charging results. 
 P. Beckmann, “Scattering by composite rough surfaces,” Proc. IEEE , vol. 
 The constant output produced by shaping the  doppler-amplifier frequency-response characteristic is not only helpful in lowering the dy­ namic range requirements of the frequency-measuring device, but the attenuation of the low  frequencies effects a reduction of low-frequency interfering noise. Lowered gain at low alti­ tudes also helps to reduce interference from unwanted rellections. The response at thc uppcr  end of the frequency characteristic is rapidly reduced for frequencies beyond that correspond­ ing to maximum range. 
 This approach maximizes the coherent signal integration in each doppler filter and provides clutter attenuation over a larger range of doppler frequencies than achievable with a single MTI filter. Thus one or more clutter filters may suppress multiple clutter sources located at different doppler frequen- cies. An example of the use of an MTD doppler filter bank against simultaneous land and weather clutter (Wx) is illustrated in Fig. 
 Thus Sec. 15.8 will discuss the design and performance of doppler filter banks, and a detailed discussion of clutter maps will follow in Sec. 15.14. 
 Above frequencies of 3000 Me/see, space-charge tubes such astriodes cease entirely tobe practical sources ofr-fpower, while magnetrons produce pulse powers 320. SEC. 10.1] CONSTRUCTION 321 ofthe order ofhundreds ofkilowatts atfrequencies ashigh as24,000 Me/see. 
 This results in a different doppler frequency for each scatterer. If we assume the lo- cations to be random, as most theories do, the received signal is the same as one coming from a set of oscillators with random phases and unrelated frequencies. This same model of a group of randomly phased, different-frequency oscillators is used to describe noise; thus the statistics of the fading signal and the statistics of random noise are the same. 
 R. Valenzuela and R. Laing, “On the statistics of sea clutter,” Naval Res. 
 SEARCH 63  MODE TO RANGE ON PREVI 
 PULSE COMPARISONS  THE MEASURED TRANSMITTER ERRORS ARE USED TO DERIVE A DIGITAL FILTER THAT COMPENSATES FOR THE TRANSMITTER NOISE THAT ARRIVES IN THE RECEIVER DIGITAL SIGNAL PROCESSOR 4.# COMPENSATES FOR INTRA 
 TION MODEL IS SPHERICAL SPREADING WHERE THE TRANSMITTER AND RECEIVER ARE FAR REMOVED &)'52%  %LEVATED DUCT 
 Figure 3shows two change map results with different dictionary sizes. Algorithm 3 Generating change maps •Difference Image: Xdi f=|Re f erence −Mission| •T raining Data: Divide Xdi finto hxhnon-overlapping blocks. •Dictionary Generation: Use the K-SVD algorithm to generate an overcomplete dictionary. 
 TRACKING RADAR 187  10. Field. J. 
 (5) The DEM image in slant range is transformed to the ground range by proposed polar coordinate transformation method. (6) The DEM of the scenes is used to assist ArcSAR imaging. A ﬂow chart of the above method is shown in Figure 6. 
 Stated clearly in words the Rada r cross- section  € σ of a target is the projected area of metal  sphere (where the projected area of a sphere is a circle with A= πr2) which would return the  same amount of power to the Radar as the actual target.  . Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 88        € x,y,z Coordinates   € θi,φi Azimuth and elevation angle of the incident wave front   € θi,SφS Azimuth and elevation angle of the scattered wave front   € Rr Range from origin to the receiving antenna   € Rt Range from origin to the transmitting antenna      €   E t Radiated electric field strength      €   E i Electric field strength of the incident wave front      €   E r Electric field strength at the receiving ante nna  € Pt,Pr Transmitting and receiving power   € Gt,Gr Gain of the transmitting and receiving antennas   € Lt,Lr Losses at the transmitter and receiver   € Lp Losses due to polarization effect (not shown)  Figure 11.1  Transmission scheme and coordinate system with abbreviations for the illustration  of the Radar equation for an object according to Equation (11.1). 
 L., and G. E. Uhlenbeck (eds.): "Threshold Signals," MIT Hadialion Laboratory Series,  vol. 
 17.17a. Provi- sion ismade forgrid modulation byallofthe signals and foradditional plate modulation bysynchronization pulses. Negative video and syn- chronization signals are amplified byathree-stage broadband video amplifier. 
  HAD IN COMMON  ^ 
 In order to approach a  thumbtack-like ambiguity function, the order of the frequencies needs to be more ran - dom in nature. The order of frequencies is the code, and it is generated via a special class  of M × M Costas arrays. Costas41,44 suggested a technique for selecting the order of these  frequencies to provide more controlled range and doppler sidelobes. 
 This allows all construction details, including those  required for polarization filtering, to be incorporated into the slot characterization;  sufficient accuracy is difficult to achieve using numerical analysis. Provided the char - acterization is done carefully and good manufacturing techniques can guarantee toler - ances, it is reasonably straightforward to produce affordable antennas that meet IMO  requirements. The required vertical beamwidth is normally obtained by a linear flare. 
   2!$!2 #2/33 3%#4)/.   £{°ÎÇ 4HE RESULTING IMAGINARY PART OF THE PROPAGATION CONSTANT ATTENUATES WAVES TRAVELING  THROUGH THE MATERIAL -OST OF THE COMMERCIAL VERSIONS OF $ØLLENBACH ABSORBERS ARE FLEXIBLE AND CAN BE  APPLIED TO MODESTLY CURVED SURFACES 4HE DIELECTRIC ABSORBERS ARE TYPICALLY MADE OF A RUBBERY FOAM  SOMETIMES URETHANE  IMPREGNATED WITH CARBON PARTICLES )MPREGNATION MAY BE PERFORMED BY DIPPING A COMPRESSED SLAB OF MATERIAL IN A GRAPHITE SUSPENSION BATH  THEN WRINGING IT OUT AND DRYING IT -AGNETIC $ØLLENBACH LAYERS CAN BE ROLLED FROM A MIXTURE OF NATURAL OR SYNTHETIC RUBBER LOADED WITH CARBONYL IRON OR FERRITE POWDERS 4HE LOWER THE POWDER CONTENT  THE MORE FLEXIBLE THE SHEET BUT THE LESS EFFECTIVE ITS ELEC 
 FIGURE 18.15  Artist’s impression of Magellan observing the surface  of Venus, backlit by the sun, featuring the radar (and high-gain communi - cations) antenna and the smaller horn antenna for the altimeter ( Courtesy  of NASA ) ch18.indd   48 12/19/07   5:15:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 There are some problems, however, in the use of  solid-state devices for ratlar systems other than cost.  RADAR TRANSMITTERS 219 ;r;;: .,!;', , .., .l~;••'.';',I,\.\.'\'. I••( Figure6.15AN/TPS-59 L-nand radar.The30ftby15ftantenna consists of54rowsof24elements each. 
 TERMINAL SEMICONDUCTOR DEVICES THAT ALLOW A SMALL VOLTAGE OR  CURRENT TO CONTROL A LARGER VOLTAGE OR CURRENT 3OME CROSS SECTIONS OF COMMON TRANSISTOR TYPES USED IN  THE DESIGN OF RADAR TRANSMITTERS ARE THE  A  'A!S -%3&%4   B  'A!S 0(%-4  C   3ILICON -/3&%4   D   3ILICON ,$-/3 &%4  E   3ILICON "*4  AND  F  'A. (%-4 ON 3I# 3UBSTRATE .   3/,)$ 
 Nail. Electronics Con/. (Chicago). 
  62 COSX   WHICH IS CONSISTENT WITH THE  DEFINITION FOR DOPPLER SHIFT STATED AT THE BEGINNING OF THE CHAPTER  &IGURE  ILLUSTRATES THE VARIOUS CLUTTER DOPPLER FREQUENCY REGIONS AS A FUNCTION  OF THE ANTENNA MAIN 
 13.6; and for strong winds (above about 30 kn) there is a tendency for it to level off. In fact, the con- vergence of the lines in Fig. 13.90 and b with increasing wind speed suggests that the reflectivity of the sea surface is tending toward Lambert's law, for which there is no dependence on grazing angle, frequency, or polarization but only on surface albedo. 
 and tilerefore is more applicable to the phased array, has been called the fi.ued-hmru.  approach; or more descriptively, thea~ism~~~eu/se.48 Two asymmetrical patterns are  generated and squinted above the horizon to minimize response to the surface-reflected signal.  ?'he two patterns are constrained so that their ratichhas an even-order symmetry about the  horizon. 
 A RADAR PULSE COMPRESSION SIGNAL  WITH UNIQUE CHARACTERISTICS v  )%%% 4RANS !EROSPACE AND %LECTRONIC 3YSTEMS   VOL   NO     PP n  -ARCH   ( * "LINCHIKOFF  h2ANGE SIDELOBE REDUCTION FOR THE QUADRIPHASE CODES v )%%% 4RANS !EROSPACE  AND %LECTRONIC 3YSTEMS  VOL   NO   !PRIL   PP n  . ,EVANON  h3TEPPED 
 Kenington, Z. B. Popovic, N. 
 Rarton. D. K. 
 Thus it was proved that the system was  extremely accurate, and that the tying-up of the German  and British maps had been done successfully. When you  realize that the bombing in this case, as with all similar  Oboe ventures, was done really by the ground operator,  some hundreds of miles away from the target, or from  the operator dropping the bombs, the system appears all  the more remarkable.  How do the ‘cat’ and ‘mouse’ stations get their ranges  by radar? Remember that the aircraft carries only a  mobile transmitter-receiver, and no measuring device. 
 CALLED DAWN 
 7, 1959,   pp. 27–41.  96. 
 TOR IT IS STEERED BY PHASE SHIFTERS IN THE DESIRED DIRECTION  BUT IT SCANS WITH FREQUENCY AS INDICATED BY %Q  4HE ARRAY FACTOR IS SCANNED BY ADJUSTING THE FREQUENCY 
 All radars are susceptible to off- frequency interference, which, unless it is filtered before reaching the mixer, may create a detectable output in the desired IF band. The ability of MTI or pulse doppler processing to suppress clutter may be de- graded if the receiver filter is not perfectly stable. The receiver's transfer char- acteristic (gain, time delay, and bandpass or impulse response) must be constant so that its effect on each echo pulse is identical. 
 Knott, “RCSR Guidelines Handbook,” Final Technical Report on EES/GIT Project   A-1560-001,” Engineering Experiment Station, Georgia Institute of Technology, April 1976. ch14.indd   46 12/17/07   2:47:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 (Distribution unlimited.)  74. Cogdell, l R .. et al.: High Resolution Millimeter Reflector Antennas. 
 TIie multiple-time-around echoes on the A-scope cannot be distin-  guislied from proper target echoes actually within the maximum unambiguous range. Only the  rarige measured for target A is correct; those for B and C are not.  One method of distingwishing multiple-time-around echoes from unambiguous echoes is  to operate with a varying pulse repetition frequency. 
 TIES SUCH AS THE !RECIBO RADAR TELESCOPE   %XPERIENCE HAS SHOWN THAT THERE IS  RELATIVELY LITTLE ADDED VALUE IN THE PHASE BETWEEN THE LIKE 
 MeteoroL, vol. 15, pp. 452-466, 1958. 
 GRAZING ILLUMINATION AND SHADOWING OF ROUGH SURFACES v  2ADIO 3CI  VOL    NO   PP n  -AY 
 IV-12, pp. 303-312. 46. 
 10  n8 = 50 n8 = 20 n8 = 10 n8 5  o~~--'-~~-'-~----'-~--'-~-'-~'-'-~_.___.___.~~~~~~~~~~~  0·001 0 01  (a) . m u  I  E u  l?  c a.,  E a.,  > 0 0 E 50  40 - 30  20  10 "  0  0001 MT! AND PULSE DOPPLER RADAR 137  001  Figure 4.32 Effect or limit level on the improvement factor ror (a) two-pulse delay-line canceler and  (b) three-pulse delay-line canceler. C/L = ratio of rms clutter power to limit level. 
 L.: Genesis or a Generator: The Early History of the Magnetron, J. Fra11kli11 lflst.,  vol. 255, pp. 
  .KFT  TO  -KM OR  TO  -KFT .ORMAL 
 L. Mitchell, and W. L. 
 21.18  Antenna  .............................................................  21.18 Receiver-Transmitter  .........................................  21.19 Storage and Recording  ...................................... 
 The chaff is made of elemental passive reflectors that can be floated or  otherwise suspended in the atmosphere or exoatmosphere for the purpose of confusing,  screening, or otherwise adversely affecting the victim electronic system. Examples are  metal foils, metal-coated dielectrics (aluminum, silver, or zinc over fiberglass or nylon  ch24.indd   5 12/19/07   6:00:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Spot beams inherently imply loss of covera ge, and  the overall power efficiency is quite low. The antenna sy stems have large space and weight re- quirements, and necessitate large -area solar panels for power generation. Nevertheless, SAR- systems with T/R modules are the best avai lable with the presen t technology and will continue to  be launched during the next few years. 
 and J.R. Barnum, “Theoretical limitation of the sea on the detection of low  doppler targets by over-the-horizon radar,” IEEE Trans. Ant. 
 MS PULSE LENGTH AND A  BEAMWIDTH  WOULD NEED  D" MORE SUBCLUTTER VISIBILITY THAN A RADAR WITH A  
             .   -4) 2!$!2  Ó°x£ 3ELECTION OF FILTERS IS BASED ON CLUTTER AMPLITUDE INFORMATION STORED IN A CLUTTER MAP  4HE FILTERS ARE SELECTED ON A RANGE 
 33-37, November, 1978.  342INTRODUCTION TORADAR SYSTEMS 134.Hansen, R.c.:Workshop onConformal Arrays,MicrowalJe J.,vol.18,p.28,October, 1975. 135.Hsiao,J.K.,andA.G.Cha:Pallerns aodPolarizations ofSimultaneously ExcitedPlanarArrayson aConformal Surface,IEEETrans.,vol.AP-22,pp.81-84,January, 1974. 
 D. Blair, and G. A. 
 For example, in one particular design of a four-bit  microstrip X-band phase shifter, using a sapphire substrate, it proved expedient to use the  loaded-line construction for the 22.5 and 45° bits, and to use the hybrid coupled circuit for the  90 and 180" bits to obtain minimum insertion loss with reasonable bandwid~Jt and power  handling capability. 21 The switching times of phase shifters utilizing PIN diodes can be as low  as 50 ns. Typically, switching of the order of one microsecond is suitable for most applications. 
 11. L. B. 
 22.Paoli,L.:SeaClutterCancellation &Attenuation inModern MarineRadars,RivistaTeclliaSelt'nia, (Rome,Italy),vol.3,no.4,pp.1-9,1976. 23.Croney,J.:Improved RadarVisibility ofSmallTargets inSeaClutier,TheRadioandElecrrollic Engineer, vol.32,pp.135-148, September, 1966.. 24. 
 Any use is subject to the Terms of Use as given at the website. Sea Clutter. 15.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 the fact that the excitation of the surface-wave system depends on the local apparent  wind  at the surface, so there can be significant differences in waveheight according  to whether the wind is blowing with or against the current. According to Eq. 
 ASV Mk. VIA, transmitter (A) and attenuator (B) mounted on the port side in the nose of the aircraft [ 10].Airborne Maritime Surveillance Radar, Volume 1 4-19. 4.6 ASV Mk. 
 4.16. The pulse . MTI AND PULSE DOPPLER RADAR 115  Q,.\ 1.0  Vl  § 0.8 a  ~ 0.6  .E: 0.4 -¥ 0.2  0::  1/,; 2/r; 3/,; 4/Tj  rrequency  (a)  1.0 - Q,.\ .,,  g 0.8 - 0. 
 66.Howard, D.D.:HighRange-Resolution Monopulse Tracking RadarandApplications, EASCON '74 Record.pp.86-91,IEEEPublication 74CHO883-1AES. 67.Provejsil, D.J.,R.S.Raven,andP.Waterman: "Airborne Radar," D.VanNostrand Co.,Inc.. Princeton. 
 781--789, July, 1978.  68. Williams, P. 
 K. R. Roth, M. 
 We should by now be able to understand the basic  points of the range-amplitude radar display. We see a  faint greenish or blue line (depending on the afterglow-  factor type of tube employed), with perhaps a large blip  at one end of the line representing the transmitter pulse,  surrounded by a group of PE’s, the permanent echoes  from neighbouring objects; or the outfit may more  likely be of the type where the pulse and perhaps the  PE’s too are suppressed. As the gain control of the  radar receiver is turned up we see the thin time-base line  increase in thickness and take the appearance of a grass  carpet, as the noise background of the receiver causes  thousands of little impuises across the Y plates. 
 R. C. Burgener, and S. 
 Intheexample ofFig.4.16,theblindspeedsarecoincident for4fTI=5/T2• Although thefirstblindspeedmaybeextended byusingmorethanoneprf,regionsoflow sensitivity mightappearwithinthecomposite passband. TheclosertheratioT1:T2approaches unity,thegreaterwillbethevalueofthefirstblind speed.However, thefirstnullinthevicinityofId=1fTIbecomes deeper.Thusthechoiceof T1/T2isacompromise between thevalueofthefirstblindspeedandthedepthofthenulls withinthefilterpassband.Thedepthofthenullscanbereduced andthefirstblindspeed increased byoperating withmorethantwointerpulse periods.Figure4.17showstheresponse ofafive-pulse stagger(fourperiods) thatmightbeusedwithalong-range airtrafficcontrol radar.8Inthisexample theperiodsareintheratio25:30:27:31andthefirstblindspeedis 28.25timesthatofaconstant prfwaveform withthesameaverageperiod.Iftheperiodsofthe staggered waveforms havetherelationship nllTI=n2IIi=.,.=nNITN,wherent.n1.•...,nN areintegers, andifVBisequaltothefirstblindspeedofanonstaggered waveform witha. 116 INTRODUCTION TO RADAR SYSTEMS  Figure 4.17 Frequency response of a five-pulse (four-period) stagger. 
 Iftheradardesigner hasachoice,itis preferred thatthehighsidelobes benearthemainbeam,wheretheyarceasiertorecognize, ratherthantohaveisolated highsidelobes elsewhere. Thisisonetimenatureiscooperative sinceitisnaturalforthesidelobes tobelargeinthevicinityofthemainbeam. TheTayloraperture illumination hasalsobeenappliedtosynthesizing thepatterns of circular, two-dimensional antennas.86.87Ithasbeenwidelyusedasaguideforselecting antenna aperture illuminations. 
 Limited in-plane sea clutter measurements have been taken.43' *109 The Domville data1 contains a broad range of B1-, 6^ measurement conditions but unfortunately estimates only wind conditions and not sea state. For vertical polarization, the Domville X-band data109 and the Pidgeon C-band data43 show spreads of about 10 dB, and their averages match within ±5 dB. For horizontal polarization, the Domville X- band data109 and the Pidgeon X-band data107 again show spreads of about 10 dB, but the match is only about ±10 dB. 
 SELECTED THREAT IS SERVICED FIRST 0ASSIVE MODES ARE INTERLEAVED WITH ACTIVE OPERATION TO IMPROVE SURVIVABILITY AND PASSIVE TRACKING AND )$ %ACH MODE SHOWN IN &IGURE  IS OPTIMIZED IN REAL TIME FOR THE PARTICULAR COMBI 
 oxygerl tnolcc~~lc Ilas resotlatices at 60 (;11~ (0.5 cril wavelctigth) and 118 GHz.~~ At frequen-  cies below about 1 C; tiz (L bard) tlie effect of atmospheric attenuation is negligible. Above  10 Gf 17. it ~CCOII~CS ilicr~asi~~gly ir~lj~ort;tl~t. 
 An example of a simple  transformation of this type would be sidelobe canceler architecture where the beam  transformation would generate a sum channel main beam and select elements from the  aperture as sidelobe cancellers. Post-Doppler, Element Antenna STAP.  The second type of transformation  leads to what are called post-doppler STAP architectures. 
 The synchro secondary and thedeflec- tion coil (which iswound inastandard synchro stator form) have 3-phase rather than 2-phase windings. The equipment islight inweight, com- paratively simple and economical. Its principal drawbacks are the limited duty ratio, the precision required inthe triggering circuit, and the limited off-centering attainable. 
 Boston. May11--14,1976,paper30-5,Reprinted inMierolVtll'e JOllrl/al. vol.21,pp.5963.March. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section.  RADAR CROSS SECTION  14.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 FIGURE 14.13  Measured RCS of a large naval auxiliary ship for horizontal incident polarization. 
 Samczynski, P .; Kulpa, K. Coherent mapdrift technique. IEEE T rans. 
 18. R. H. 
 VIDES FLEXIBILITY FOR CONVENIENTLY GENERATING ACQUISITION GATES FOR AUTOMATIC 
 Santa, and G. M. Kirkpatrick. 
 STATE CONDITION WILL BE ACHIEVED WHERE THE WIND PROVIDES JUST ENOUGH ENERGY TO THE WAVES TO BALANCE THAT LOST BY BREAKING AND OTHER DISSIPATION MECHANISMS -OREOVER  IN THIS STATE OF DYNAMIC EQUILIBRIUM  ENERGY WILL BE TRANSFERRED &)'52%   3CHEMATIC REPRESENTATION OF BLIND SPEED BANDS IN WHICH SHIP ECHOES ARE OBSCURED  BY SEA CLUTTER                
 Substituting the approximated Laplacians into the Euler–Lagrange equations, a single matrix equation can be derived: Af=g(¯f), (8) where A=⎛ ⎜⎜⎜⎝I2 x+λs IxIy−IxI−Ix IxIy I2 y+λs−IyI−Iy −IxI−IyII2+λm I −Ix−Iy I 1+λc⎞ ⎟⎟⎟⎠,f=⎛ ⎜⎜⎜⎝u v mt ct⎞ ⎟⎟⎟⎠,g(¯f)=⎛ ⎜⎜⎜⎝λs¯u−IxIt λs¯v−IyIt λm¯mt+ItI λc¯ct+It⎞ ⎟⎟⎟⎠. These equations have to be solved iteratively. The solution is given by: f=A−1g(¯f), (9) where A−1=1 α⎛ ⎜⎜⎜⎜⎜⎜⎜⎜⎝λcλmλs+λmλs+ I2λcλs+I2 yλcλm−IxIyλcλm IxIλcλs Ixλmλs −IxIyλcλmλcλmλs+λmλs+ I2λcλs+I2 yλcλmIyIλcλs Iyλmλs −IxIλcλs IyIλcλs(I2 x+I2 y)λcλs+ λcλ2 s+λ2 s−Iλ2 s Ixλmλs Iyλmλs −Iλ2 s(I2 x+I2 y)λmλs+ λmλ2 s+I2λ2 s⎞ ⎟⎟⎟⎟⎟⎟⎟⎟⎠ and α=λmλ2 s+I2λcλ2 s+( I2 x+I2 y+λs)λcλmλs. 
 When the pulse is  reflected it is simultaneously reversed in polarity, so the  resultant wave-form at the input end consists of a  number of square waves, each of a duration twice the  . 500 HOW RADAR WORKS  time taken for the pulse of energy to travel from the  input end of the line to the short-circuited end. Another  delay line may be used to provide a second series of  square pulses, at time intervals delayed with respect to  the first. 
 It lias the further advantage of having reduced  temperature sensitivity. Instead of using a number of individual toroids of different lengths in  cascade. a single long section of toroid is used that is capable of providing the total differential  phase shift of 360". 
 Until 2004,  such radars did not have an internationally recognized standard for manufacturers to  follow. IEC 6225215 is now the agreed international radar standard for “craft not in  compliance with IMO SOLAS Chapter V” and was initially issued at the instigation  of manufacturers. Now an increasing number of national maritime administrations  are insisting that all new small craft radars sold in their jurisdiction conform to this  standard. 
 Our proposed RCS curve denoising method can preserve the useful information and obtain a good denoising effect. 258. Sensors 2019 ,19, 346      (a) (b) (c) (d)  Figure 12. 
 SUPPLIED DATA  ESPECIALLY FOR CHART RADARS RADARS UTILIZING AN ELECTRONIC CHART 
 38.  pp. 1053-1056, September, 1950. 
 Zhu, S.; Ran, D. Multi-angle SAR image fusion algorithm based on visibility classiﬁcation of non-layover region targets. In Proceedings of the 2017 International Conference on Security, Pattern Analysis, and Cybernetics (SPAC), Shenzhen, China, 15–17 December 2017; pp. 
 Transmitted Spectra. -Consider now aradar system ofageneral type, asdescribed from the Fourier-analysis point ofview, either bya diagram such asFig 52 or,more precisely, byaFourier series (or integral) forsome transmitter voltage orcurrent. Such aseries might be written as E= z~new, (2) and weknow that ifCO.=nu, such aseries can represent any periodic’ function. 
 This may lead to incorrect results in some  cases since the optical line of sight does not necessarily correspond to the radar line of sight, as  explained in Sec. 12.6. ·  The four-thirds earth approximation has several limitations. 
 TO 
 16, pp. 49–51,  December 1983. 40. 
 Other de- sign principles involved in low antenna sidelobes are the use of radar-absorbent material (RAM) about the antenna structure, the use of a fence on ground instal- lations, and the use of polarization screens and reflectors. This means that very low sidelobe antennas are costly in terms of size and complexity when compared with conventional antennas of similar gain and beamwidth characteristics. Sec- ond, as the design sidelobes are pushed lower and lower, a point is reached where minor error contributions to scattered energy (random errors) or misdirected ra- diation (systematic errors) become significant. 
 R. Wyatt, “A relaxation method for integral inversion applied to HF radar measurement of the  ocean wave directional spectrum,” Int. J. 
 74 CHO 934-0  NEREM.  43. Muehe, C. 
 MERCIAL SYSTEMS FOR  YEARS !LSO  IT WAS OBSERVED THAT SUCH DISPLAY SYSTEMS COULD ACCOMPLISH MORE THAN ONE FUNCTION AND NOT JUST BE USED FOR SHOWING RADAR ON A CHART 4HIS ANTICIPATED THE CONCEPT OF MULTIFUNCTION DISPLAYS  NOW IN USE ON SOME INTEGRATED BRIDGE SYSTEMS )T IS INTERESTING TO NOTE THAT +ELVIN (UGHES AND $ECCA OBTAINED THE FIRST TYPE  APPROVAL FOR COMMERCIAL MARINE RADAR IN  EFFECTIVELY  BOTH ARE STILL SUPPLYING .   #)6), -!2).% 2!$!2   ÓÓ°ÎÎ MARINE RADAR TODAY +ELVIN (UGHES HAS RETAINED ITS NAME AND $ECCA IS INCORPORATED  INTO THE 3PERRY -ARINE ORGANIZATION OF .ORTHROP 'RUMMAN #ORPORATION 4HE  +ELVIN (UGHES 4YPE  RADAR HAD A PEAK POWER OF  K7   §S PULSE WIDTH  AND A 02& OF   (Z 4HE  FT  METER  CHEESE ANTENNA HAD HORIZONTAL AND VERTICAL BEAMWIDTHS OF  AND   RESPECTIVELY  ROTATING AT  RPM 4HERE WAS AN ANTENNA HEATER TO PREVENT ICING  AND THE TRANSMITTER AND THE RECEIVER TO )&  WERE hUPMASTv INTEGRATED WITHIN THE ANTENNA TURNING UNIT  4HE DISPLAY WAS A  IN  CM  CATHODE RAY TUBE PLAN POSITION INDICATOR 4HE SIMILARITIES WITH SYSTEMS BEING SOLD IN THE ST CENTURY ARE PERHAPS MORE SURPRISING THAN THE OBVIOUS DIFFERENCES  -/Ê"Ê ,/ 
 M. S.: Developments in Ground Mounted Air Supported Radomes, IEEE 1977 Mechatlical  Engineering in Radar Sympositon, Nov. 8-10, 1977, Arlington, Va., pp. 
 The next person, who recognized the importance of the Radar effect, was Marconi.  As a young  man Marconi had exhaustiv ely pursued the work of Heinrich Hertz and had constructed his  communication experiments upon it.  In 1922 he gave a fiery speech before the Institute of Radio  Engineers (IRE) in London. 
 172 Squadron, Chivenor, ﬂying Wellington XII with Leigh Light (taken from the pooled maintenance scheme of 172 Figure 3.11. Sea return discriminator circuit.Airborne Maritime Surveillance Radar, Volume 1 3-17. and 407 squadrons), were undertaken by CCDU in May 1943 [ 13], when the radar had been in service for only about two months. 
  
 NOISE RATIO COMPUTED FROM AN  METER 
 BEAM TUBES 4WYSTRON 4HE BANDWIDTH OF A CONVENTIONAL KLYSTRON IS LIMITED PRIMARILY BY  THE BANDWIDTH OF THE OUTPUT RESONANT CAVITY )F A COUPLED CAVITY SLOW 
 Itactsasthecoherent reference neededtodetectthedopplerfrequency shift.Bycoherent itismeantthatthephaseof thetransmitted signalispreserved inthereference signal.Thereference signalisthedistin­ guishing featureofcoherent MTIradar. IftheCWoscillator voltageisrepresented asA1sin2rrt;r,whereA1istheamplitude and .r,thecarrierfrequency.thereference signalis Vrer=A1sin2rr.f;r andthedoppler-shifted echo-signal voltageis V .[2(rt')4rrt;Ro]echo=A3Sillrr.ll±.dr--~.-- whereA1=amplitude ofreference signal A3=amplitude ofsignalreceived fromatargetatarangeRo ,f.J=doppler frequency shift t=time c=velocityofpropagation Thereference signalandthetargetechosignalareheterodyned inthemixerstageofthe receiver. Onlythelow-frequency (difference-frequency) component fromthemixerisofinter­ estandisavoltagegivenby ,(a)(4.3) (b)Figure4.1(a)SimpleCWradar;(b) pulseradarusingdoppler informa­ tion.. 
 IMENTS v $IG )NT 'EOSCI 2EMOTE 3ENSING 3YMP )'!233    )%%% #( 
 GAUSSIAN NATURE OF CLUTTER REQUIRES HIGHER THRESHOLDS IN  THE MAIN BEAM AND NEAR SIDELOBES 4HRESHOLD CROSSINGS ARE CORRELATED IN RANGE AND  DOPPLER AND BUFFERED ALONG WITH CORRESPONDING PHASE CENTER DISCRIMINANTS  WHICH ARE PRESENTED TO TRACKING FILTERS OR ACTIVITY COUNTERS 4HERE ARE THREE REGIONS OF THRESHOLDING MAIN 
 • A Doppler shift only occurs when  the relative velocity vector has a radial component.  In general there will be both radial and tangential components to the velocity•• •123 vr  wave fronts expanded1 2 4 3 4  wave fronts compressed1 2 4 3 4 WAVE FRONT  EMITTED AT  POSITION 1WAVE FRONT  EMITTED AT  POSITION 2 R decreasing ⇒dR dt<0⇒fd>0 (closing target) R increasing ⇒dR dt>0⇒fd<0 (receeding target)  r v t   r v r  r v  • R2/drfvλ =−. 33Doppler Filter Banks • The radar’s operating band is divided into narrow sub-bands. 
 ESA and its member states authorized a replacement.  The CryoSat orbit has a high-inclination (92 °) and a long-repeat period (369 days, with  a 30-day subcycle), designed to provide dense interlocking coverage over the polar  regions. Its aim is to study possible climate variability and trends by determining the  variations in thickness of the Earth’s continental ice sheets and marine sea ice cover. 
 69-76, 1976. 60. Zawadzki, L: Factors Affecting the Precision of Radar Measurements of Rain, Preprints, 22d Conf. 
 Theaverage powerrequired fortheplanararrayofthedome antenna isapproximately thesumoftheaverage powersrequired foreachoftheindividual arrays,assuming comparable performance. Ithasbeenclaimed thatthedomeantenna isoflesscostthanfourarraysofconventional designcovering thesamevolume. However, anycomparison ofthistechnique withconven­ tionalantennas mustbedoneonthebasisoftheentireradarsystemanditsintended applica­ tion,notjusttheantenna. 
 ONLY MEMORY &)'52%  "LOCK DIAGRAM OF CLOSED 
 6.1d to minimize the area and especially to minimize the torque required to turn(a) (b) (c)f/D FIG. 6.6 Edge taper due to the spreading of the spherical wave from the feed ("space loss"). DECIBELS . 
 T. Root and J. M. 
 This is usually true for commercial aircraft  and for satellites with nearly circular orbits. A radar whose purpose is the measurement of  elevation angle, and which usually does not measure the azimuth angle, is called a height-finder  radar. A radar which measures the elevation angle along with the azimuth angle (and range) is  called a JD radar. 
 The Venera  spacecraft were in approximately ∼24-hour polar orbits with a periapsis ∼1000 km,   at 62 °N latitude, and apoapsis ∼65,000 km. Magellan  mapped over 98% of the surface of Venus (Figure 18.14) with imag - ing resolution an order of magnitude better than the earlier Venera  missions.101  FIGURE 18.14  The impact crater Golubkina on the surface of Venus imaged  by Magellan  (S band, HH-polarized). The 30 km (19 mile) diameter crater is  characterized by terraced inner walls and a central peak, typical of large impact  craters on Earth, the Moon, and Mars. 
 BAND NOISE MAY BE ADDED TO WHITEN THE !$ CONVERTER QUANTIZATION NOISE AND SPURIOUS SIGNALS 4HE OUT 
 LAYER PROPAGATION IS ONLY ^ KM  THOUGH NORMALLY THE LAYER IS NOT TOTALLY REFLECTING  SO SOME ENERGY CONTINUES UPWARD TO THE & 
 Beste, D. C.: Design of Satellite Constellations for Optimal Continuous Coverage, IEEE Trans., vol. AES-14, pp. 
 LIMITED ALTIMETERS IDEALIZED MEAN  &)'52%  A  4HE ALTIMETERS PULSE TYPICALLY  M LONG AFTER  COMPRESSION  SEQUENTIALLY ENCOUNTERS OCEANIC SURFACE WAVES OF HEIGHT  UP TO  M OR MORE   B  3EA 
 DOMAIN CONVOLUTION FILTERING WITH  AN IMPULSE RESPONSE     ;LINE =   ;LINE =   HT       ;)      J1=   HT       )   HT        J1   HT        )      J1  7HEN THE FILTER OUTPUTS ARE VIEWED AS COMPLEX SIGNAL ;LINE =    )   J1   !EJP  THE  COMPLEX MAGNITUDE  ! AND ANGLE  P GIVE THE AMPLITUDE GIVE OR TAKE A SCALE FACTOR  AND  PHASE OF THE )& SIGNAL  BECAUSE THE ORIGINAL )& SIGNAL COULD BE RE 
 The drive wire is oriented for minimum RF  coupling. It is also important to have proper mechanical contact between the toroid and the  waveguide wall since an air gap can give rise to the generation of higher-order modes that can  result in relatively large narrow-frequency-banJ, insertion-loss spikes. Cardul allention must  be paid to eliminating these gaps without excessive mechanical pressure that coulJ cause  magnetostriction which changes the magnetic properties of the material. 
 For the same reason (i.e., RF drive is already present) there is little starting-time delay in the desired CFA operating mode; but the ir-mode oscillation has a finite starting time and will pro- duce little energy if the voltage passes quickly enough through the range in which it can occur. In a de-operated CFA, the ir-mode oscillation should not occur at all because the cathode voltage is at full value all the time. Klystrons. 
 The  assumption of a perfectly reflecting plane earth applies in but a few cases. Also assumed was an  omnidirectional antenna pattern in the elevation plane. Since radars utilize directive antennas,  the idealized antenna lobe structure as given by Eq. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar.  BISTATIC RADAR  23.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 26. 
 H., and R. H. Sekhon: Objective Determination of the Noise Level in Doppler Spectra. 
 The more directive the element, the fewer that are needed  to fill a given aperture.  Another important consideration· in the selection of an antenna element and the design of  an array, is the mutual coupling between the radiating elements. When thei field intensity  pattern of an array antenna was .considered previously [Eq. 
 The radar range equation is derived initially for a point target, and when that equation or the subsequent equations derived from it are used to predict the detection range for distributed targets, complications arise. In many cases, however, the point-target equation can be used for distributed targets by em- ploying a suitable "effective" value of a (Sec. 2.8). 
 (The radiation intensity is the power radiated per unit solid angle in a given  direction.) The power density at the target from an antenna with a transmitting gain G is  Power density from directive antenna = :;;~2 (1.4)  The target intercepts a portion of the incident power and reradiates it in v~rious directions. 4 INTRODUCTION TO RADAR SYSTEMS  The measure of the amount of incident power intercepted by the target and reradiated back in  the direction of the radar is denoted as the radar cross section a, and is defined by the relation  Power density of echo signal at radar = P, G2 ~ 4rrR 4n:R ( 1.5)  The radar cross section a has units of area. It is a characteristic of the particular target and is a  measure of its size as seen by the radar. 
 Next, one determines the modulation orrepetition frequency j,. Asinpulse systems, this depends onthemaximum range. But whereas inpulse systems j,may actually beasmuch asc/2r, inthepresent systems one must have f,markedly less than c/2r inorder that not too large a fraction ofthetime will bewasted while thesign ofthebeat frequency is changing. 
 P4, and n1. (After Marcum.to courtesy IRE  Tra11s.) . 32 INTRODUCTION TO RADAR SYSTEMS  and probability of false alarm, or false-alarm number, since there is no standardiLution of  definitions. 
 62 COSX   WHICH MAKES  THE LATER EQUATION FOR DOPPLER SHIFT CONSISTENT WITH THE ONE PRESENTED AT THE BEGINNING OF THE CHAPTER  )LLUSTRATED IN &IGURE  IS THE RECEIVED PULSED SPECTRUM WITH RETURNS FROM DISTRIBUTED CLUTTER  SUCH AS THE GROUND OR WEATHER  AND FROM DISCRETE TARGETS  SUCH AS AIRCRAFT  AUTOMOBILES  TANKS  ETC &IGURE  SHOWS THE UNFOLDED SPECTRUM IE  NO SPECTRAL FOLDOVER FROM ADJACENT  02& LINES  IN THE CASE OF HORIZONTAL MOTION OF THE RADAR PLATFORM  WITH A SPEED  6 2  4HE CLUTTER 
 (ii) A wideband backscatter sounder, that is, a low- power, low-resolution radar that sweeps across the HF band, measuring echo strength  versus time delay (group range), to see which frequencies are illuminating any given  region. (iii) A mini-radar, similar to a backscatter sounder, that employs a narrowband  waveform to study the doppler structure of the echoes as a function of group range  for selected frequencies. (iv) A network of remote beacons or transponders to provide  coordinate registration. 
 LENGTH "LASS MATRIX OR A  2OTMAN LENS &OR $ SCANNING THESE TECHNIQUES BECOME QUITE COMPLEX !NOTHER TECHNIQUE FOR IMPROVING THE BANDWIDTH BY A CONSIDERABLE FACTOR IS TO USE AN  ARRAY OF SUBARRAYS 4HE RADIATING ELEMENTS OF A PHASED ARRAY MAY BE GROUPED INTO SUBAR 
 Z PLANE.   2%&,%#4/2 !.4%..!3   £Ó°x WHERE K IS THE WAVELENGTH &OR A ROUND REFLECTOR OF DIAMETER  $  THIS APERTURE GAIN  LIMIT IS  AP'$ ¤ ¦¥³ µ´P L    )N PRACTICE  IT IS SOMETIMES USEFUL TO DESCRIBE REFLECTOR GAIN BY DECREMENTING THE  APERTURE GAIN BY SUBTRACTING VARIOUS APERTURE RADIATION LOSSES SUCH AS SPILLOVER  TAPER  EFFICIENCY  FEED BLOCKAGE  REFLECTOR LEAKAGE  SURFACE DISTORTION  STRUT BLOCKAGE  FEED ALIGN 
 5.1 the amplitude  fluctuations are assumed to be larger than servo noise. If not, the improvement of monopulse  tracking over conical scan will be negligible. In general, the tracking accuracy deteriorates at  r~,both short and long target ranges, with the best tracking occurring at some intermediate range. 
 CLEAR REGIONS VERSUS TARGET ASPECT ANGLE .OTE THE TARGET IS AT THE CENTER OF THE  PLOT WITH THE RADAR PLATFORM ON THE CIRCUMFERENCE                    
 The signal power S returned from a target with cross section a, is  Combining Eqs. (13.5) and (13.6), the signal-to-clutter ratio for a target in a background of  surface clutter at low grazing angle is  S - - d,  C - a0ROB(cr/2) sec 4  If the maximum range R,,, corresponds to the minimum discernible signal-to-clutter ratio  then the radar equation can be written  In this equation, the clutter power C is assumed large compared to receiver noise power. This  is an entirely different form of the radar equation than when the target detection is dominated  by receiver noise alone. 
 34, no. 46, pp. 114, 115, 117. 
 1948.  79. Rllodes. 
 ALIAS FILTERING L 2EDUCED COMPONENT COST  SIZE  WEIGHT  AND POWER DISSIPATION 4HE USE OF A HIGH )& FREQUENCY IS DESIRABLE AS IT EASES THE DOWNCONVERSION AND  FILTERING PROCESS HOWEVER  THE USE OF HIGHER FREQUENCIES PLACES GREATER DEMANDS ON THE PERFORMANCE OF THE !$ CONVERTER $IRECT 2& SAMPLING IS CON SIDERED THE ULTI 
 Insome cases, thetimer exerts precise control of exact firing time ofthernodulat orbysendingit atriggerpulse;in others, itresponds toatrigger from themodulator. Inthelatter case, thesys- tem issaid tobe‘iself-synchronous. ”1Although certain advantages can often bederived bygiving control tothe timer, this cannot always bedone,z and itissometimes inconvenient inamultiple-display system. 
 This configuration is generally  restricted to true-lime-delay circuits and to low-power, miniaturized phase shifters where loss  is not a major consideration. For a four-bit phase shifter, covering 360°, the minimum number  of diodes needed in the periodically loaded line is 32, the switched line requires 16, and the  hybrid-coupled circuit needs only 8. The theoretical peak power capability of the switched line  is twice that of the hybrid-coupled circuit since voltage doubling is produced by the reflection  ,-!' ·I f.. 
 Zheng, X.C.; Tang, H.M.; Qin, Z.M. Study on the imperilments of soft foundation and land subsidence in Wuhan. Geol. 
 Sir Robert Watson-Watt pioneered  and developed radar, and it is possible to draw a parallel  between his magnificent work in this branch of radar  physics and the pioneer work of the Stephensons father  and son, in the development of the locomotive‘ If the  name of Watson-Watt should rank equal with that of  Edison, Alexander Graham Bell, or of other pioneers it  is partly because radar now at this moment in the world’s  history holds a potentiality at least as great as that“facing  these earlier men of science.  Before taking up the threads of the recent story of  radar it is interesting to look back to the year 1926,  when British Patent No. 292,285, applied for by John  Baird, described an arrangement which now bears a  striking resemblance to H2S,! which we now know to  be one of the most advanced radar techniques. 
 184 6.12 Height-6nding with aFree-space Beam. 187 6.13 Homing .......... .196 6,14 Precision Tracking ofaSingle Target 203 6.15 Precision Tracking during Rapid Scan 210 CHAP. 
 ON TARGET  6 4  COSX4      IS CLEAR OF SIDELOBE  CLUTTER  WHEREAS IF THE RADAR IS IN TRAIL BEHIND THE TARGET  X4    AND  X      THE  TARGETS RADIAL VELOCITY HAS TO BE GREATER THAN TWICE THAT OF THE RADAR TO BECOME CLEAR OF SIDELOBE CLUTTER 4HE SIDELOBE CLEAR AND CLUTTER REGIONS CAN ALSO BE EXPRESSED IN TERMS OF THE ASPECT  ANGLE WITH RESPECT TO THE TARGET  AS SHOWN IN &IGURE   (ERE  COLLISION GEOMETRY  IS ASSUMED IN WHICH THE RADAR AND TARGET AIRCRAFT FLY STRAIGHT 
 Report 7725. June 7. 1974. 
 BASED QUAD 
 Lett. 2009 ,6, 772–776. [ CrossRef ] 14. 
 In addition, Brennan’s rule22 indicates that to achieve an  adaptive solution within 3dB of the optimum answer requires 2 N (N is the number of  degrees of freedom) independent interference samples contributing to the adaptive  weight estimate. With antenna array sizes in tens to hundreds of elements and CPI  lengths of tens to hundreds of pulses, the number of degrees of freedom can quickly  get quite large, resulting in not only fairly complex adaptive weight processing but  also the more difficult problem of obtaining adequate sample support from clutter and  jamming interference for a given adaptive weight solution. As such, it is important to explore various STAP architecture options imbedded in a  radar design solution. 
 Beyer: V-Ream Antennas for tfeight Finding, AFCRC-TR-56-115. Air Force Canthridge Xrsrurclr  Center, December, 1956. AD 1 1701 5. 
 Henceitmaybeconcluded thatforsmallsignal-to-noise ratiosthesquare-law detector maybeasuitable approximation totheoptimum detector, whileforlargesignal-to-noise ratiosthelineardetector ismoreappropriate. Inpractice, itmakeslittledifference whichofthe twodetector lawsisused.Thedifference between thesquare-law andthelineardetectors was shownbyMarcum43toproduce lessthan0.2dBdifference intherequired signal-to-noise ratio.Ifonehasachoice,thelinearlawmightbepreferred because ofitslinearity and,hence, itslargedynamic range.Thelineardetector, likeanydetector law,approaches thesquare-law characteristic forsmallsignal-to-noise ratios. Logarithmic detector. 
 CIALLY INCLUDING INTERFEROMETRY  AND POLARIMETRY 4HIS IS PARTICULARLY RELEVANT TO  SPACE 
 This near field sensing is illustrated in Figure 13.13.  The near field is also referred as the cut - in zone and here a higher resolution is required than in the far field.  At present the ACC R a- dar detectors do not provide special measu res for a particular detection or acquisition at close  range. 
 30·3 1  (This assumes that the normal log-FTC has a logarithmic characteristic from -20 d 8 below  the receiver noise to + 80 dB above noise.) In the log-log receiver the higher clutter values  (tails of the distribution) are subjected to greater suppression.  Adaptive video threshold. Other receiver techniques than the log-FTC were discussed in  Sec. 
 The use of waveguide simulators as developed by Wheeler Laboratories has made it possible to determine the matching structure experimentally without the need of building an array. A waveguide, operating in a TE10 mode, may be considered to contain two inclined-plane waves propagating down the guide. The angle that each of the plane waves makes with the longitudinal direction (Fig. 
 The non-Rayleigh nature of the clutter must be properly considered in the detector  design if large increases in the minimum detectable signal-to-clutter ratios are to be avoided.  Pulse width. The radar equation that applies to the detection of targets in surface clutter at low  grazing angles (Eq. 
 Substitution of Eq. (21.17) into Eq. (21.18) gives a fourfold integral for the out- put, namely, eQ = J JJJp(*0^)/[' ~ y] f\t - ^] dt dx dy dz (21.19) If the order of integration can be inverted so that the integration with respect to t is performed first, one can define a quantity x(x,y,z;x',y'tz'). 
  
 E. Hiatt: Butler Network Extension to Any Number of Antenna Ports, I EE£  Trnns., vol. AP-18, pp. 
 LINE 
 PLE AT A RATE THAT IS CONSIDERABLY LOWER THAN THE ANALOG FREQUENCIES BEING SAMPLED  IT MIGHT SEEM ATTRACTIVE TO DO AWAY WITH THE RECEIVER ALTOGETHER AND SAMPLE THE 2& SIGNAL DIRECTLY !LTHOUGH THIS IS POSSIBLE  !$# LIMITATIONS RESTRICT THE PERFORMANCE OF SUCH ARCHITECTURES &IRST  THE ANALOG FRONT END OF AN !$# HAS A LOWPASS  D" CUTOFF FREQUENCY SPECIFIED BY THE MANUFACTURER !$# INPUT FREQUENCIES SHOULD BE KEPT WELL BELOW THIS CUTOFF 3ECOND  AS SHOWN PREVIOUSLY IN &IGURE   SAMPLING THE 2& SIGNAL DIRECTLY WILL DRAMATICALLY INCREASE THE SLEW RATE OF THE SIGNAL PRESENTED TO THE !$#  THUS REQUIRING VERY LOW LEVELS OF 2-3 CLOCK JITTER !LSO  THE !$# HAS INHERENT NONLINEARITIES THAT PRODUCE SPURS IN THE !$# OUTPUT  A PROBLEM WHICH TYPICALLY WORS 
 Figure 12.33 shows a typical waveguide feed horn model and its  associated local coordinate system. Based on an appropriate application of equivalence principle and the induction  theorem,42–44 the currents induced on the reflector can be determined from the feed  FIGURE 12. 33 Waveguide feed horn model  and coordinate system ch12.indd   31 12/17/07   2:31:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 £Ç°Ó  2!$!2 (!.$"//+  K DIVIDED BY THE APERTURE DIAMETER  P" y K  $ 4HE CORRESPONDING LINEAR CROSSRANGE  RESOLUTION AT RANGE 2 IS THEN   DL CRy2 $    REAL APERTURE     &OR EXAMPLE  IF  K    CM 8 BAND  AND  $    M  P" y  RADIANS !T A RANGE OF  2     KM  THE CROSSRANGE RESOLUTION WOULD BE  2 P" y  KM  HARDLY FINE ENOUGH TO RESOLVE  SUCH TARGETS AS BUILDINGS AND VEHICLES (OWEVER  BY USING APPROPRIATE COHERENT PROCESS 
 25.14  Pseudo-Monostatic RCS Region  ........................  25.15  Bistatic RCS Region  ..........................................  25.17  Glint Reduction in the Bistatic RCS Region  ........ 
 D.C. Dec. 11, 1969. 
 2.4will beobtained. The average noise power, however, isjust proportional to@according toEq. (16) and isrepresented bytheline bofFig. 
 The x's in the figure represent  the position of the ra<lar a11tc1111a each time a pulse is transmitted. If the echo received at each  position is stored and if the last II pulses are combined (added together), the effect will be  similar to a linear-array antenna whose length is the distance traveled during the transmission  of the n pulses. The "clement" spacing of the synthesized antenna is equal to the distance  traveled by the aircraft between pulse transmissions, or de vTP = v/f~, where TP is the pulse­ repetition period and./~ is the pulse-repetition frequency. 
 17.7 illustrates analternative c-wmethod which avoids this difficulty. Here thephase-shifted signal isaharmonic ofthereference signal and is derived from itbyafrequency multiplier. Thus thetwo signals can be transmitted without confusion onthesame subcarrier. 
 When a new detection is received, an attempt is made to associate it with existing  tracks.96 This is aided by establishing for each track a small search region, or gate, within  which a new detection IS predicted based on the estimate of the target speed and direction. It is  desired to make the gate as small as possible so as to avoid having more than one echo fall  within it when the traffic density is high or when two tracks are close to one another. However,  a large gate area is required if the tracker is to follow target turns or maneuvers. 
 L.: Genesis of a Generator: The Early History of the Magnetron, J. Fru~ililitl Itist.,  vol. 255, pp. 
 Avariable lowercutoffmightbe advantageous whenthewidthoftheclutterspectrum changes withtimeaswhentheradar receives unwanted echoesfrombirds.Arelatively widenotchatzerofrequency isneededto removemovingbirds.Ifthenotchweresetwideenoughtoremovethebirds,itmightbewider thannecessary forordinary clutteranddesiredtargetsmightberemoved. SinceIheappear­ anceofbirdsvarieswiththetimeofdayandtheseason,itisimportant thatthewidthofIhe notchbecontrolled according tothelocalconditfons . • J w iI!},fLJL[ w0 ~='1r 2~' 3~ a: .,Frequency Figure4.20Freq!Jency-response characteristic ofanMTIusingrangegatesandfilters.. 
 2.5  Pulse Radar Equation  ........................................  2.6  Detectability Fact or  ............................................  2.6  Probabilistic Notati on  ......................................... 
 HORIZON DETECTION v  0ROC  )%%% )NT 2ADAR #ONF    PP n . 
 The f1-score is then given as f1score =2×Precision ∗Recall Precision +Recall, (4) The results of the experiment are summarized in Table 8. 306. Sensors 2019 ,19,6 3 T able 8. 
 Spectral Characteristics.  The spectral characteristics of clutter, as discussed in  most references, implicitly assumes that the radar transmits a continuous, constant PRF  waveform. The spectrum of the output of a pulsed transmitter using a simple rectangular  pulse of length t  is shown in Figure 2.11. 
 The cooperative transmitter is controlled by allied or friendly  forces; the noncooperative transmitter, by hostile or neutral forces. Table 23.2 sum - marizes bistatic radar applications in these operating regions. * Entries in the dedicated transmitter/co-site category represent a complete bistatic  radar suite—radars with all components including the transmitter designed for  bistatic operation. 
 MerrillI.Skolnik. CHAPTER  ONE  THE NATURE RADAR  1.1 INTRODUCTION  Radar is an electromagnetic system for the detection and location of objects. It operates by  transmitting a particular type of waveform, a pulse-modulated sine wave for example, and  detects the nature of the echo signal. 
 SEA CLUTTER  15.396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 17. O. M. 
 The chapter sections are organized by measure - ment theme, taken in a broad sense. These themes are Earth-orbiting synthetic aperture  radar (SAR), radar altimetry (which in the SBR context almost always implies obser - vation of the Earth’s oceans and larger surface water bodies), planetary radars (where  “planet” includes planetoids such as large moons), scatterometers (whose data associ - ate a geophysical parameter such as oceanic wind speed to the observed calibrated  radar backscatter properties of the illuminated surface), and sounders (which includes  both atmospheric and subsurface radar systems). Each section includes an overview of  all relevant SBRs, noting key turning points or watershed innovations in the theme’s  history. 
 It has been suggested that the compromise value of  Q,/OB be abbut 0.28, corresponding to a point on the antenna pattern about 1.0 dB below the  peak.'.I  Other considerations. In both the sequential-lobing and conical-scan techniques, the measure-  ment of the angle error in two orthogonal coordinates (azimuth and elevation) requires that a  minimum of three pulses be processed. In practice, however, the minimum number of pulses in  sequential lobing is usually four-one per quadrant. 
 Why Pulsed? Radar transmitters would be much less complex and costly if they could simply operate CW (continuous-wave) like broadcast stations. Having to generate very high pulsed RF power leads to much higher operating voltages (both dc and RF), energy storage problems, and the necessity for high- power switching devices. Some RF devices, like Class C amplifiers (tube or solid-state), are self-pulsing and draw current only when RF drive is applied, but most microwave tubes require some type of pulse modulator (Sec. 
 37. S. A. 
 ,",  
 Thus, for comparable geometries, the intrinsic gain for a GaAs device will be substantially higher than for a silicon device. The cell design and geometry configuration of power GaAs FETs follow design rules similar to those used by designers of silicon bipolar devices. Fig- ure 5.5 shows the cross section of a power GaAs FET that uses air bridge construction and via holes to ground the source terminal of the FET. 
 IEEE Geosci. Remote Sens. Lett. 
 (Courtesy of Raytheon Company ) PATRIOT.116 The PATRIOT is a multifunction phased array radar system devel - oped by Raytheon for the Army in the form of a lens using an optical feed, as shown  previously in Figure 13.30. Sum and difference patterns are separately optimized with  a monopulse feed. The aperture is round and contains approximately 5000 elements. 
 128,   pp. 275–295, 1981. 158. 
 Phased Array Radars  Radars with fixed electronically scanned antennas designed  for many functions such as missile detection and air traffic control, and used con - currently for measuring precipitation rates. As an example, the design of elliptic MTI filters as used in the TDWR will be  described. TDWR is a C-band radar used at airports for detection of downbursts,  microbursts, and prediction of wind direction. 
 thesystemresponse maybedegraded. Forexample, irtheenergy (al (b)Figure8.4Seriesarrangements for applying phaserelationships inan array.(0)fedfromoneend: (b)center-fed.. were to arrive in a direction other than broadside, the entire array would not be excited  simultaneously. 
 29. Lyzenga, D.R. Effects of Wave Breaking on Sar Signatures Observed Near the Edge of the Gulf Stream.In Proceedings of the International Geoscience & Remote Sensing Symposium, Lincoln, NE, USA, 31 May 1996. 
 VARYING WEIGHTS IS DESIRABLE DEPENDS ON WHETHER THE STAGGER . 
 4.29. These data apply  at a frequency of 1000 MHz. The experimentally measured power spectra of clutter signals  rnay he approximated by  where lV(f) = clutter-power spectrum as a function of frequency  g(,f) = Fourier transform of input waveform (clutter echo)  .fb = radar carrier frequency  a = a parameter dependent upon clutter  Values of the parameter a which correspond to the clutter spectra in Fig. 
 Thus, if the best noise figure over the band is used in the radar equation, a loss factor has to be  introduced to account for its poorer value elsewhere within the band.  If the receiver is not the exact matched filte.r for the transmitted waveform, a loss in  signal-to-noise ratio will occur. Examples are given in Table 10.1. 
 For reflectors of cqilal gain (saliie ciinlitctcr it1  w:ivelerigtlis) Eel. (7.32) shows that the relative sidelobe level causccl by errors will increase  -;IS [tic foilrtll power of (lie freqilency, or 12 d~/octave.'  ,411 i~iiportant co~iclusion is that the details of the radiation pattern, especially in the  region outside tlie ~iiairi beam, are more likely to be determined by the accuracy witti which tlie  antenna is constructed than by the manner in which the aperture is illuminated. Thus  the tiiecltatiical crlginecr aiid the skilled tuacllitiist and tccllnician are just as i~i~portarit as  the :lntentia tiesigner in realizing the desired radiation pattern. 
 (4) Careful attention must  be paid to unplanned voltage stresses on the power amplifier, either from transient  induced effects or load impedance variations in order to maintain the desired reli - ability. (5) For efficient multiple-stage designs, it is necessary that the final stage of  the amplifier reach saturation before the preceding stages. This must be addressed in  the circuit design. 
 S{'riesl's.parallel feeds.Therelativephaseshiftbetween adjacent elements ofthearraymust he1>=2rr(cljA)sin00inordertoposition themainbeamoftheradiation patternatanangle (/0'Thenecessary phaserelationships between theelements maybeobtained witheithera series~recl oraparallel-fed arrangement. Intheseries-fed arrangement, theenergymaybe transmitted fromoneendoftheline(Fig.8.4a),oritmaybefedfromthecenterouttoeach end(Fig.8.4h).Theadjac~nt elements areconnected byaphaseshifterwithphaseshift1>.All thephaseshiftersareidentical andintroduce thesameamountofphaseshift,whichislessthan 2rrraJians. Intheseriesarrangement ofFig.8.4awherethesignalisfedfromoneend,the position ofthebeamwillvarywithfrequency (Sec.8.4).ThusitwiIlbemorelimitedin handwiJth thanmostarrayfeeJs.Thecenter-fed feedofFig.8.4bdoesnothavethisproblem. 
 MAGNETIC 00-  SYSTEM THAT CONSISTS OF A SERIES OF MAGNETIC LENSES ! MULTICAVITY KLYSTRON CAN HAVE ITS BANDWIDTH INCREASED BY STAGGER TUNING THE  CAVITIES  SIMILAR TO THE MANNER IN WHICH STAGGER TUNING IS DONE IN AN )& AMPLIFIER OF A SUPERHETERODYNE RECEIVER TO OBTAIN BROADER BANDWIDTH )T IS MORE COMPLICATED  HOWEVER  TO DO THIS IN THE KLYSTRON SINCE THE VELOCITY MODULATION THAT APPEARS AT EACH INTERACTION GAP CONTRIBUTES A COMPONENT TO THE EXCITING CURRENT AT THE SUCCEEDING GAPS  SOMETHING THAT DOES NOT OCCUR IN AN  )& AMPLIFIER 4HE EARLY 6! 
 SEVEN DESIGN AIDS FOR ANTENNAS  PROPAGATION EFFECTS AND SYSTEMS PLANNING v  -ICROWAVES  PP n  -AY .   0(!3%$ !22!9 2!$!2 !.4%..!3   £Î°ÇÎ  & * (ARRIS  h/N THE USE OF WINDOWS FOR HARMONIC ANALYSIS WITH THE DISCRETE &OURIER TRANSFORM v  0ROC )%%%  VOL   PP n  *ANUARY   4 4 4AYLOR  h$ESIGN OF LINE SOURCE ANTENNAS FOR NARROW BEAMWIDTH AND LOW SIDELOBES v  )%%%  4RANS  VOL !0 
 ARRAY RADAR IS  M LONG  MOUNTED ON A  (EAVY %XPANDED  -OBILE 4ACTICAL 4RUCK AND CAPABLE OF BEING TRANSPORTED IN A # 
 One method of determining range with a  pulsed waveforrtl is to measure the time at which the leading edge of the pulse crosses sonie  threshold' (Fig. 11.1). The pulse uncorrupted by noise is shown by the solid curve. 
 The persistence can be varied from a fraction of a second to several  minutes, or 10nger.~' From five to seven gray-scale ranges are typical.2b The direct-view  storage tube can also be obtained with two colors and the shades in between."  The direct-view storage tube generally is capable of less resolution than a conventional  CRT. Also, the continuous buildup on the storage medium of strong, fixed clutter echoes  when the persistence is long can result in a loss of picture quality due to a loss of resolution  and a loss of contrast caused by the brightening of the dark area immediately surrounding  the blip.  Another method for achieving a bright display is the scan converter. 
 140. Skolnik, M. I.: Resolution of Angular Ambiguities in Radar Array Antennas with Widely-Spaced  Elements and Grating Lobes, IEEE Trans., vol. 
 75, pp. 551 563, Jan. 20. 
 Figure 4.4. Attenuator schematic, type 53 and type 58 [ 6].Airborne Maritime Surveillance Radar, Volume 1 4-6. 4.2.6 Switch unit The layout of switch unit 207B is shown in ﬁgure 4.7. 
 Sensors 2019 ,19, 2161 By substituting the equations above and considering the Fresnel assumption (which means ∂2U/slashbig ∂z2≈0), the PWE in geomagnetic coordinate is expressed as ∇2 ⊥U=−k2 0ΔεrU+2j∂U ∂xk0sinθcosϕ+2j∂U ∂yk0sinθsinϕ+2j∂U ∂zk0cosθ (15) Please note that the dispersion induced by background ionosphere is not considered in the simulator, so the ﬂuctuating part Δεrin Equation ( 15) is neglected in the following derivations. Since the ionosphere irregularities are considered to be a very thin phase screen, the diffraction effect is neglected within the irregularity layer and the propagation path is considered to be a straight line for SAR signals. Based on the aforementioned assumptions, the complex amplitude of transmitted waves which has penetrated the phase screen is expressed as U(ρ⊥,0+)=U(ρ⊥,0)·ejφ(ρ⊥), where ρ⊥is the distance vector in the x-y plane and the φ(ρ⊥)is the scintillation phase corresponds to the penetration point on phase screen. 
 With a HF emitter successive horizontal and vertical polarized si g- nals are send, while both polarizations are simultaneously fed into the measuring channels.  In  the receiver the signals of the test and reference channel are converted to IF in a phase - preserving way.  Then, the ratio of both signals according to magnitud e and phase is calcu- lated. 
 Instead of the uniform panel sizes of Fig. 7.29, the space-frame radome can use a  quasi-random selection of different panel sizes to minimize periodic errors in the aperture  distribution which can give rise to spurious sidelobes. It also tends to make the radome  insensitive to polarization. 
 Aperture Radar Technol. Conf., Las Cruces, N. Mex., Mar. 
 1)uplexers would be required as in a microwave phased-array radar. The antenna might also  support several simultaneous, irldcpendellt radar beams; or multiple beams can be generated  sequentially (a pulse burst). A narrow, steerable beam in the elevation plane is desired for  OTH radar in order to avoid multipath propagation and to concentrate the energy at the  desired range. 
 CARRIER &- RANGING IS USED TO OBTAIN A RANGE MEASUREMENT  AS DESCRIBED IN 3ECTION  4HIS RANGE MEASUREMENT COMES AT THE EXPENSE OF FRAME TIME WITH THE ADDITION OF VARIOUS &- SLOPES FOR EACH DWELL 4HE ACCURACY OF THIS RANGE MEASUREMENT IS DEPENDENT UPON THE LINEAR &- RANGING SLOPES !LERT#ONFIRM 4HE BEAM AGILITY OF %3! 
                   #! &%    $"( #!$  %      '"(  #!$  %  '              . 
 27. H. McNairn et al., “Identification of agricultural tillage practices from C-band radar backscatter,”  Canadian Journal of Remote Sensing , vol. 
   NO   PP n  .OVEMBER   2 .ITZBERG  h#LUTTER MAP #&!2 ANALYSIS v )%%% 4RANS  VOL !%3 
 ORDER THEORY  "Y USING  THE ANTENNA GAIN CONVENTIONS STATED EARLIER AND ASSUMING A SEMI 
 TO 
 SELS  AND MANY ARE REQUIRED TO CARRY MORE THAN ONE RADAR 4HREE OR EVEN MORE RADARS ARE SOMETIMES CARRIED VOLUNTARILY BY LARGE SHIPS 2ADAR FORMS AN IMPORTANT PART OF A VESSELS TOTAL NAVIGATION EQUIPMENT FIT )NCREASINGLY  THE BRIDGE OF A SHIP IS DESIGNED AS AN INTEGRATED CONCEPT  COVERING NAVIGATION  COMMUNICATIONS  ENGINE CONTROL  AND CARGO MONITORING FACILITIES &IGURE  ILLUSTRATES A MODERN  INTEGRATED BRIDGE SYSTEM   )"3  AS FITTED ON A CRUISE SHIP 4HE RADAR DISPLAYS ARE SEEN TO FORM A PROMINENT PART OF THE SYSTEM 2ADARS FITTED ON SMALLER FISHING VESSELS AND LEISURE CRAFT SHARE MANY OF THE FEATURES OF RADARS DESIGNED FOR SHIPS BUT ARE NECESSARILY MORE COMPACT A TYPICAL SMALL BOAT RADAR IS SHOWN IN &IGURE  3PECIFIC REQUIREMENTS FOR THESE RADARS  WHERE THEY DIFFER TO ANY EXTENT FROM THE DESIGN OF SHIPBORNE RADARS  ARE DISCUSSED WITHIN RELEVANT PARTS OF THE CHAPTER 2ADAR FOR 643 IS SEPARATELY COVERED IN 3ECTION  4HE CHALLENGES FACING DESIGNERS OF SHIPBORNE RADAR ARE DETAILED WITHIN 3ECTION   4HESE RADARS HAVE TO MEET CERTAIN INTERNATIONAL STANDARDS  WHICH ARE DISCUSSED IN 3ECTION  3ECTION  CONCENTRATES ON THE TECHNOLOGY  AND 3ECTION  LOOKS AT TARGET TRACKING 2ADAR TARGETS ARE BEING INCREASINGLY DISPLAYED WITH ELECTRONIC CHART DATA AS AN UNDERLAY 4HIS IS OUTLINED IN 3ECTION   TOGETHER WITH OTHER USER INTERFACE ISSUES 3ECTION  LOOKS AT THE LINKS BETWEEN RADAR AND THE RELATIVELY NEW  !UTOMATIC  )DENTIFICATION 3YSTEM !)3   WHICH REPLICATES SOME FUNCTIONS PREVIOUSLY PROVIDED SOLELY BY RADAR -ARINE RADAR BEACONS  INCLUDING RACONS   3EARCH AND 2ESCUE 4RANSPONDERS   3!24S   AND  2ADAR 4ARGET %NHANCERS  24%S   ARE DESCRIBED IN 3ECTION  4HERE IS  A SHORT DISCUSSION IN 3ECTION  ON SHIPBORNE RADAR PERFORMANCE VALIDATION TESTING  &)'52%  3HIPS INTEGRATED BRIDGE SYSTEM #OURTESY OF 3!- 
 M. E. Parke, R. 
 4, p. 237, 1922.  4. 
 R. Smith, C. M. 
   PP n   *ULY   2 " -ACK  h"ASIC DESIGN PRINCIPLES OF ELECTROMAGNETIC SCATTERING MEASUREMENT FACILITIES v  2OME !IR $EVELOPMENT #ENTER 2EPT 2!$# 
  A6 )  
 PATTERN OUTPUTS ARE AVAILABLE  BUT THEY HAVE  CONTRADICTORY REQUIREMENTS FOR OPTIMUM AMPLITUDE DISTRIBUTIONS THAT CANNOT BOTH BE SATISFIED !S A RESULT  EITHER GOOD SUM OR GOOD DIFFERENCE PATTERNS CAN BE OBTAINED !T THE COST OF SOME ADDITIONAL COMPLEXITY  THE DIFFICULTLY CAN BE OVERCOME BY THE METHOD SHOWN IN &IGURE  C 4WO SEPARATE CENTER 
 F. Gabriel, “Adaptive digital processing investigation of DFT sub-banding vs. transversal  filter canceler,” Naval Research Laboratory, NRL Report 8981, July 28, 1986, Washington,  DC (USA). 
 Oct.25-28.1977, pp.145-149, lEE(London) Conference Publi­ cationno.155.. CHAPTER  SIX  RADAR TRANSMITTERS  6.1 INTRODUCTION  The radar system designer has a choice of several different transmitter types, each with its own  distinctive characteristics. The first successful radars developed prior to World War I1  employed the conventional grid-controlled (triode or tetrode) vacuum tube adapted for opera-  tion at VHF, a relatively high frequency at that time. 
 WAY  HALF 
 The superiority of the monostatic radar even seems to extend to the application of the radar  fence. Although less equipment is needed with the bistatic-radar fence, this advantage is offset  to a large extent by the difficulties involved in extracting the target's position.  The bistatic radar deserves credit for its historical role in the early days of radar in leading  to the development of monostatic radar. 
 104. J. Capon, “High resolution frequency-wavenumber spectrum analysis,” Proc. 
 [ CrossRef ] 20. Li, L.L.; Li, F. SAR imaging degradation by ionospheric irregularities based on TFTPCF analysis. 
 Most of these mea - surements were in the 10° to 80° range of incidence angles. Measurements near verti - cal are scarcer.15,16 Well-controlled experiments near grazing are also scarce except for  a major Lincoln Laboratory program.17 Airborne measurements are necessary to make larger scattering areas accessible.  Although airborne programs for special purposes have been legion, curves of scatter - ing coefficient versus angle for a known homogeneous area are scarce. 
 Guerlac, H. E.: "Radar in World War II," vols. I and II, Tomask/American Institute of Physics, New York, 1987. 
 Tlie tracking radar is said to be " locked on " the target when the  echo is rnaitiiained between tlie two range gates. As the target moves, the range gates automat-  ically follow. The range-gate stealer operates by initially transmitting a single pulse in synchro-  nism with each pulse received from the radar, thereby strengthening the target echo. 
 ONLY ANTENNA FEED HORN FOR THE HIGH BEAM 4HE EFFECTIVE TWO 
 Ê/1 
 118 INTRODUCTION TO RADAR SYSTEMS  Phase  detector Range  gate  No. 1  Range  gate  No.2  Range  gate  Na.3  Range  gate  No.n Boxcar  generator  Boxcar  generator  Boxcar  generator Bandpass  (Doppler)  filter Full-wave  linear  detector Low poss  filter  (integrator)  Figure 4.19 Block diagram of MTI radar using range gates and filters. Threshold  Threshold  To data ____.. 
 Track.  Target tracking is done by making range, range rate, and azimuth and eleva - tion angle measurements on targets. Range measurements are obtained using range gat - ing and centroiding on the target return with range ambiguities being resolved within the  tracker. 
 However, for an evaporation duct,  it is not the vertical extent of the duct that is important but the refractive gradient within  the duct. Changes of refractive gradients over vertical heights less than a few millimeters  may have a significant impact upon the duct’s trapping ability. Thus, assessment of the  evaporation duct is best performed by making surface meteorological measurements and  inferring the duct height from the meteorological processes occurring at the air/sea inter - face and not from direct measurements using the traditional radiosonde, rocketsonde, or  microwave refractometer. 
 2. Simulation Method of SAR Images of Oceanic Shear-Wave-Generated Eddies The simulation process was divided into two steps: Firstly, the current ﬁeld of eddy was established on the basis of the Burgers-Rott vortex model. Then, the established current ﬁeld of the eddy and sea surface wind ﬁeld were inputted into an oceanic SAR imaging simulation model, and the simulated image was obtained. 
 As l increases, there is greater risk of false association decisions; however,  the effect of this is reduced if gtrack is small. At the other extreme, when l and gtrack are  large, the tracking problem is essentially unsolvable without basic changes to the radar  design parameters to reduce them. There is an intermediate region where sophisticated  association has value. 
 The frequency does not appear explicitly in the search-radar range  equation. However, the lower frequencies are preferred for a search radar since large power  and large aperture are easier to obtain at the lower frequencies, it is easier to build a good MTI  capability, and there is little effect from adverse weather.  Different radar range equations can .be derived for different applications, depending on  the particular constraints imposed. 
 The ionospheric de- scription that has been used is for what has been termed the quiet ionosphere', there will be a few hours per year when performance is very inferior to that pre- dicted.• = CNR • =SNR o = SIZECNR or SNR (dB) Cross Section (dB above 1 Sq. Meter) . Loss (dB) Frequency (MHz) or El. 
 1, 1950.  16. Lee, Y. 
 CLUTTER  RATIO )N MILITARY SYSTEMS  HIGH RANGE RESOLUTION MAY BE EMPLOYED FOR COUNTING THE NUMBER OF AIRCRAFT FLYING IN CLOSE FORMATION AND FOR RECOGNIZING AND THWARTING SOME TYPES OF DECEPTION COUNTERMEASURES 4UNABLE BANDWIDTH OFFERS THE ABILITY TO CHANGE TUNE  THE RADAR SIGNAL FREQUENCY  OVER A WIDE RANGE OF THE AVAILABLE SPECTRUM 4HIS CAN BE USED FOR REDUCING MUTUAL INTER 
 Since the sense ofthis ine- quality isanimportant factor in allthe systems tobedescribed from here on, this section closes with afew further remarks con- cerning it. The doppler frequency is,by Eq. (l), dependent only ontho wavelength and theradial velocit]. 
 Microwave System for Point -to-point Service.-The two equipments described inSees. 17.12 and 17”13 were developed primarily forair-to-surface work involving theuseofomnidirectional antennas; an upper limit was therefore settothepossible radio frequency. The pres- entsection will describe equipment designed forusebetween fixed ground stations which permit theuse ofdirectional antennas. 
 Figure 8. The propagation coordinate system of sliding spotlight SAR signal. 190. 
 Taper is applied by introducing one amplitude ripple (n = 1) in the fre- quency domain to form W1(J). By pairs 1 and 2, the time function is the superposition of the three time-displaced and weighted (sin x)/x functions.39 Low time sidelobes are attainable in the resultant function W1(O by the proper choice of the coefficient F1. In particular, F1 = 0.426 corresponds to Hamming weighting40"42 and to the time function whose magnitude is represented by the solid curve B in Fig. 
 The GEOS-C satellite (its designation was changed to GEOS-3 after successful orbit had been achieved) was launched on Apr. 9, 1975. The nominal orbit pa- rameters were as follows: mean altitude, 843 km; inclination angle, 115°; eccen- tricity, 0.000; and period, 101.8 min. 
 44. pp. 68-72, June 21, 1971. 
 291–310, 1990. 59. W. 
 PHASED ARRAY RADAR ANTENNAS  13.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 The pattern maximum is noted to occur at less than 60 ° because the gain of the element  pattern increases toward broadside. The element pattern value at 60 ° is cos 60 ° = 0.5  in power or 0.707 in amplitude, relative to the maximum at broadside, as expected.  The sidelobes in the general region of broadside are not reduced because in that region   the element pattern is approximately unity. 
 17.19 becomes  Vfc RRδcr≤ <2 (17.20) This leads to the condition  R c V δcr≤2 (17.21) Thus, the unambiguous range Ru and the resolution of a stripmap SAR cannot be  selected independently of one another. Skolnik further points out, quoting Bayma and  McInnes,29 that more sophisticated reasoning leads to the condition  R c Vu δcr≤4 7. (17.22) ch17.indd   14 12/17/07   6:49:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 A focal-point feed is usually small to produce a broad pattern and must be compact to avoid blockage of the antenna aperture. In some cases the small size required is below waveguide cutoff, and dielectric loading becomes neces- sary to avoid cutoff. A more practical approach to monopulse-antenna feed design uses higher- order waveguide modes rather than multiple horns for independent control of sum- and difference-signal E fields. 
 S. S. Blackmun, Multiple Target Tracking with Radar Applications , Dedham, MA: Artech House,  1986, pp. 
 Magnetron frequency pulling with antenna scanning canbeobjection- able with any type oftube. Itmay becaused either byimperfect rotary joints orbyobstacles infront oftheantenna. Ifthepulling isslow com- pared with 10Mc/sec2 (see Table 16.1), ground clutter will remain can- celed atallazimuths. 
 pp. 31-36, October,  1972.  26. 
 PROTECTORS IONIZE UNDER TRANSMITTER POWER LEVELS  BUT THERE IS SOME SMALL STATISTICAL VARIATION IN  THE INITIATION OF IONIZA 
 E. Brookner, “Radar of the 80’s and beyond,” IEEE Electro 84 , May 1984.FIGURE 13.51  AN/SPY-3 Multi-Function Radar ( Courtesy of Raytheon  Company ) ch13.indd   70 12/17/07   2:41:16 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 A. I., arid C. P. 
 1," R. C. Hansen (ed.),  Academic Press. 
 +3C0 Rll~k 0,1 Ill 240k 001 0.05 ; 0.1 ... --- 6?N 7 Sk 10k 5’0 10 k 2k ‘Osollaior -N 20ma IOh●mIOGsynchm T GI chm I 311 V* 6SN7 Rotating i“+ D_ synchronism w,th antenna I +3CUU 2W ~ , *——B!as for6L6 driver I 7I4, IIAngle indicesmI I - IMixer RangeindicesinQ .....— I I I ., — dq,sweep 6AG7c%% I --- ---: 510 f 50k IOkCKCUII 1I +1 10JT I 51Nl@Ok+lW IIll i 1 T1 J-1–w -’”1+/1 a. Trngger d,scr!mmatorSweep delay muilivibfalm a-fiip’mp I Geared wifh S1 ‘Inverfer Verfical centering * sawtooth generator FIG,13.43b.—Magnetic B-SCOW, circuit details.. 
 442 INTRODUCTION TO RADAR SYSTEMS  12.2 PROPAGATION OVER A PLANE EARTH  Although there are but few situations where accurate predictions of radar propagation effects  can be made by assuming a flat rather than round earth, it is nevertheless instructive to  examine this special case. The assumption of a flat earth simplifies the analysis and illustrates  the type of changes introduced in radar coverage by a reflecting ground or sea surface.  Consider the earth to be a plane, flat, reflecting surface with the radar antenna located at  height ha. 
 It was not clear at that time that X-band would prove more suitable than S-band for the detection of schnorkel (seediscussion in chapter 7) but the schnorkel was recognised as a serious threat. In theAirborne Maritime Surveillance Radar, Volume 1 5-2. event, the war ended before this threat became signi ﬁcant but it may also be noted that post-war ASV development for Coastal Command continued with ASV Mk VII. 
 Range Innautical miles FIc, 17.16,—Field intensity vs. range for propagation ofvertically polarized signals over sea water atvarious receiving antenna heights. Transmitter antenna height, 5000 ft; frequency, 300 Mc/8ec. 
 The seeker's primary function is to generate an estimate of the inertial LOS rate. To accomplish this, it must track the target in angle and stabilize the an- tenna LOS against missile body motions, which could be erroneously interpreted as target motions. It is the accuracy of the resulting LOS rate estimate that will determine how well the missile performs. 
 POLARIZED ENERGY IS USUALLY A SMALL FRACTION OF THE RECEIVED POLARIZATION FROM TYPICAL TARGETS  AND IT IS NORMALLY REDUCED BY ABOUT  D" BY THE ANTENNA DESIGN (OWEVER  IN SPECIAL CASES  THE RESULTANT CROSSTALK CAN BE VERY HIGH AND MAY CAUSE A  LARGE TRACKING ERROR AND POSSIBLE LOSS OF TRACK &OR EXAMPLE  POLARIZATION OF A LINEARLY  POLARIZED BEACON ON A TARGET COULD ROTATE WITH TARGET ASPECT CHANGE AND  IN THE WORST CASE  APPROACH A CROSS 
 Res. Space Phys. 2014 ,119, 8648–8659. 
 When the radar  resolution is sufliciently small it is found that the sea echo is not spatially uniform, but is  corn posed of "occasional" individual targetlike echoes of short duration that result in a spiky  appearance on a radar display. On an A-scope display it is found that sea clutter appears more  spiky for horizontal than for vertical polarization, when the radar looks up or downwind  rattier than crosswind, at low radar freqitcticies rather than for high, and for low grazing angles  rather tliarl for high grazing  angle^.^ To resolve the individual spikes tlie radar pulse widtli  should be several tells of nanoseconds ratlier than microseconds. An individual spike might  have a radar cross section at X band of the order of magnitude of one square meter (tnore  or less). 
 ch02.indd   96 12/20/07   1:52:16 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 Curves of cross section as a function of aspect and a knowiedgc of  the trajectory with respect to the radar are needed to obtain a true description of the dynami-  cal variations of cross section. The probability-density function gives the probability of finding  any particular value of target cross section between the values of a and a + (10, while the  autocorrelation function describes the degree of correlation of the cross section with time or  number of pulses. The spectral density of the cross section (from which the autocorrelation  function can be derived) is also sometimes of importance, especially in tracking radars. 
 They must be sheltered if they are to continue to survive and perform under advcrse  weather conditions. Antennas which must be operated in severe weather are usually enclosed  for protection in a sheltering structure called a radome. Radomes must be mechanically strong  if they are to provide the necessary protection, yet they must not interfere with the normal  operation of the antenna. 
 The variability of ground conditions, as well as the physics of EM wave propa - gation and reflection, must be carefully taken into account in attempting to classify  targets even after image processing. For example, the depth image of a void is always  apparently smaller than its physical size; corner reflectors of any reasonable size gen - erate large apparently discontinuous reflection images; and conductive targets, which  reverberate by means of stored energy, create extended depth images. The image of  a buried target generated by a GPR will not, of course, correspond to its geometrical  representation. 
 Therefore, the aspect entropy will be lower than the truth value. Although there is a rebound, the percentage error is still lower than it without denoising when the SNR is high. The simulation result shows that our denoising method is effective. 
 Interpolation is the process by which the sample rate of a  signal is increased, for example in preparing the signal to be upconverted to an IF,  as shown in Figure 25.25. Interpolators are typically FIR filters with a lowpass filter  response. To increase the sample rate by a factor R, R –1 zeroes are first inserted  between the low-rate data samples, creating a data stream at a sample rate R times  faster than the input rate (upsampling). 
 58. S. Satoh and J. 
 CF—crest factor; FF—form factor.. SEC. 14.3] DIRECT-DRIVEN ALTERNATORS 559 For loads approaching 1kw, particularly inthe case ofsystems with heavy current demands, weight savings can beappreciable if3-phase generation isemployed. 
 Larson, R. W., et al.: Bistatic Clutter Data Measurements Program, Environmental Research Institute of Michigan, RADC-TR-Il-389, AD-A049037, November 1977. 112. 
 During reception, the transmitter is off and neither the TR nor the A TR is fired. The open  circuit of the A TR, being a quarter wave from the transmission line, appears as a short circuit  across the line. Since this short circuit is located a quarter wave from the receiver branch-line,  the transmitter is effectively disconnected from the line and the echo signal power is directed to  the receiver. 
 Any use is subject to the Terms of Use as given at the website. Radar Receivers. 6.6 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 Spurious Free Dynamic Range (SFDR).  SFDR is the ratio of the maximum sig - nal level to that of largest spurious signal created within the receiver. 
 A plot of the single-polarization brightness temperature or space temperature due to both  cosmic noise and atmospheric· absorption is shown by the solid curves of Fig. 12.11. An  ambient temperature of 260 K is· assumed in the computation of atmospheric-absorption  noise. 
   2!$!2 2%#%)6%23   È°££ 4HE RECEIVER FRONT END MAY ALSO INCLUDE A LIMITER  USED TO PROTECT THE RECEIVER CIR 
 ( a) Traditional imaging processing; (b) imaging processing of proposed approach (mixed Euclidean norm); complex images of channels 1 and 2 (ﬁrst and second layers); interferometric phase images (third layer); ﬁnal 3-D imaging results (last layer). 176. Sensors 2018 ,18, 3750 From Tables 5and 6, it can be found that by applying the traditional approach, position consistency of all scattering points in images of different channels cannot be ensured. 
 67. Hiatt. R. 
 INDUCED CROSS SEC 
 39-47, 1956.  U. Page, R. 
 Therefore, the coherent integra - tion time available during each CPI is reduced from the total CPI time by the sum of  the space charge time and the transient settling time. The canceler settling time can  be eliminated by precharging  the canceler with the steady-state input value.39 This is  done by changing the canceler gains so that all delay lines achieve their steady-state  values on the first IPP of data. If no canceler is used, signals can be passed to the filter bank after the space charge  is complete, so that the coherent integration time is the total CPI time minus the space  charge time. 
 availability (fraction oftimetheradarworksproperly). andmaintainability (somctimesthese lastthreeare calledRAM);elcctromagnetic compatibility (EMC)requirements; restrictions onsize.weight, cost,anddelivery: typeofprime-power available; restrictions onwarm-up timeandshut­ downprocedures; andtheforminwhichtheoutputinformation fromtheradarisdesired.The user(orbuycr)shouldattclllpt tolimilthcrequircments tostatcments ofperformance rather thangivetheminterlllsofspecificradarcharacteristics whichrestricttheradardesigner inthe choices availahle. Characteristics ofalon~-range air-surveilla'nce radar.Toillustrate thenatureofalong-range air-surveillancc radar,theARSR-J (Tablc14.1)willbedescribcd. 
 3.Selridge, H.:Proximity FuzesforArtillery, Electronics, vol.19,pp.104-109, February, 1946. 4.Bonner, H.M.:TheRadioProximity Fuse,Elec.Eng.,vol.66,pp.888-893, September, 1947. 5.Saunders, W.K.:CWandFMRadar,chap.16of"RadarHandbook," M.I.Skolnik(ed.),McGraw­ HillBookCo.,NewYork,1970. 
  
 Zverev, Handbook of Filter Synthesis , New York: John Wiley and Sons, Inc., 1967.  9. A. 
 PAVE PAWS. The PAVE PAWS (AN/FPS-115) system is a UHF solid-state active aperture phased array radar that was built for the Electronic Systems Di- vision of the U.S. Air Force by the Equipment Division of the Raytheon Company.23 The radar is a long-range system with a primary mission to detect and track sea-launched ballistic missiles. 
 INFINITE PLANES  AND FIELDS OF HEMISPHERI 
 42. T. E. 
 Substituting this velocity into the classical formula for doppler  frequency shift (Eq. (32)], and u,ing the resonant condition Aw= ).,/2, gives the doppler shift  for the resonant sea waves at gr mng incidence as  ./~ = ± .jg1i[, (14.23)  The plus sign applies to the appr,)arhing resonant wave, and the minus sign corresponds to the  receding resonant wave. When tl1e wind is hlowing toward the radar the approaching-wav~  spectral line 1s the larger of the two. 
 ARRAY LEVELS ONLY "EAM 3WITCHING  7ITH PROPERLY DESIGNED LENSES OR REFLECTORS  A NUMBER OF INDE 
 An MTI radar that measures the average doppler frequency shift of clutter qver a sampled  range interval and uses this measurement to cause the clutter mean-doppler-frequency to  coincide with the null of the MTI doppler-filter-frequency response over the remainder of the  range of observation is called a clutter-lock MTI.  One version of a clutter-lock MTI is TACCAR, which stands for time-averaged-clutter  coherent airborne radar.' Although the name was originally applied to a particular airborne  MTI radar system developed by MIT Lincoln Laboratory, it continues to be used to refer to  the clutter-lock technique that was the special feature of that system. The name is even  retained when the technique is applied to a shipboard radar or when the radar is on land and  used for the compensation of moving clutter. 
  
 Geosci. Remote Sens. 2011 ,49, 3694–3702. 
 BANCE COVARIANCE MATRIX INTO THE  5 FUNCTIONAL  A #ONSTANT &ALSE !LARM 2ATE #&!2   DETECTOR IS OBTAINED  4HUS  THE COMPARISON OF THE  5 FUNCTIONAL WITH A SUITABLE  THRESHOLD PERMITS THE TARGET DETECTION MAINTAINING THE PRESCRIBED #&!2 /NLY FOR THE RANGE CELL IN WHICH THE DETECTION OCCURRED  THE RADAR SIGNALS ARE TAKEN AND FURTHER PROCESSED BY THE -, ALGORITHM TO PRODUCE THE TARGET $O! ESTIMATE 4HE PERFORMANCE OF THE -, ESTIMATION ALGORITHM OF TARGET $O! CAN BE STUDIED  BY RESORTING TO THE #RAMER 
 A,. arid J. R. 
 J. V . DiFranco and W. 
 VARYING WEIGHTS A   PULSE TRAIN  B  TWO 
 Usually when a radar transmits a pulse at a particular polariza - tion (e.g., horizontal—H), it receives the echoes at the same polarization. Some radars  are capable of transmitting at one polarization and receiving at two orthogonal polar - izations (e.g., horizontal [H] and vertical [V] or right-circular [R] and left-circular [L]).  Furthermore, some radars can transmit at either of two orthogonal polarizations and receive  at either of the transmitted polarizations; and the choice of transmitted and received polar - izations can be varied from pulse to pulse. 
 If there is a reflecting object at a distance R, an echo signal will return after a time  T = 2Rlc. The dashed line in the figure represents the echo signal. If the echo signal is  heterodyned with a portion of the transmitter signal in a nonlinear element such as a diode, a  beat note fb will be produced. 
 . Ó{°£n  2!$!2 (!.$"//+  THE MAIN AND SIDELOBE BLANKING CHANNELS 4HE CENTER ANTENNA IS THE HIGH 
 AP-16, pp. 554–568, 1968. 67. 
 The near-field amplitude and phase are calculated at a given distance from  the origin. If this field is used as the actual illumination function, a virtual aperture is  created with the desired distribution function at the same distance behind the physical  antenna. Figure 3.21 a15 shows the phase and amplitude distribution required to form  a uniform virtual distribution displaced behind the physical aperture. 
 The goal was toprovide every friendly military ship and aircraft with atrans- ponder that would give anidentifying reply signal inresponse toproper interrogation. Since thelocation ofthe ship oraircraft inquestion was almost always determined byradar, the problem was actually one of determining thefriendly orhostile character ofradar targets. The IFF interrogating equipment was thus used inthe great majority ofcases as anadjunct toaradar set. 
 Gray, “Anti-jamming techniques for multi-channel SAR imaging,”   IEE Proc ., pt. F, vol. 133, no. 
 FACTORS AFFECTING BEARING RESOLUTION Bearing resolution is a measure of the capability of a radar to display as separate pips the echoes received from two targets which are at the samerange and are close together. The principal factors that affect the bearing resolution of a radar are horizontal beam width, the range to the targets, and CRT spot size. Horizontal Beam Width As the radar beam is rotated, the painting of a pip on the PPI begins as soon as the leading edge of the radar beam strikes the target. 
 34. A. Farina, Antenna Based Signal Processing Techniques for Radar Systems , Norwood, MA:  Artech House, Inc., 1992. 
 Î°Ó{  2!$!2 (!.$"//+  TO THE ANTENNA ELEMENTS  4EMPORAL ADAPTIVE ARRAY PROCESSING COMBINES AN ARRAY OF  SIGNALS RECEIVED AT THE SAME SPATIAL LOCATION EG  THE OUTPUT OF A REFLECTOR ANTENNA   THAT ARE SAMPLED AT DIFFERENT INSTANCES OF TIME  SUCH AS SEVERAL INTERPULSE PERIODS FOR AN ADAPTIVE -4) 3PACE 
 The antenna is a fixed array with an integral radome producing four receive  beams and four transmit beams with a minimum of 70 dB of isolation between transmit and  receive. The one-way! beamwidths are· approximately 2.5° (fore-aft) by 5° (lateral). The four  beams are displaced symmetrically'at an outward angle of 25° from the vertical. 
 being measured in the same units. At a distance given by D2/J.., the gain of  a uniformly illuminated antenna is 0.94 that of the Fraunhofer gain at infinity. At a distance of  2D2 / l. 
 TRAL PROCESSING FOR ARTIFACT REMOVAL AND SENSITIVITY IMPROVEMENT /NE OF THE MORE  IMPORTANT TASKS IS ESTIMATING THE NOISE FLOOR SO AS TO REMOVE ITS EFFECT ON THE SPECTRAL MOMENT ESTIMATES 4WO OBJECTIVE TECHNIQUES ARE COMMON   #ONSTANTLY IMPROVING  PROGRAMMABLE DIGITAL SIGNAL PROCESSING CHIPS AND SIGNAL PROCESSING COMPUTERS MAKE IT POSSIBLE FOR RADAR METEOROLOGISTS TO IMPLEMENT VARIOUS TYPES OF SPECTRUM PROCESS 
 ,., ,. ,,. SEC. 
 1290-1296, July, 1960.  47. Knott, E. 
 Academic Press. N.Y .. 1964. 
 DIGITAL !$  CONVERTER OF AT LEAST  
 This is patterned after the uni- versal curve presented in Ref. 47, except that here it is for a nonfluctuating tar- get. It is accurate to within 1 dB over the entire range (and closer over most of the range) of integration samples N from 1 to 100, probability of false-alarm val- ues PFA from 10~3 to 10~8, and probability from 1 to 99 percent. 
 If the target is within the area of rainfall, any echoes fromraindrops will further decrease its detection range. Weaker target responses,as from small vessels and buoys, will be undetectable if their echoes are notstronger than that of the rain. A very heavy rainstorm, like those sometimesencountered in the tropics, can obliterate most of the (X-band) radar picture. 
 Dyer and (i. W. Ewell: Characteristics of Snow at Millimeter Wavelcngtlts, IV76  IEEE A11te1111as a11d Propagation Sodef}' Symposium, Oct. 
 A block diagram of a digital pulse compression system is given in Fig. 10.12. The code generator generates the binary sequence, which is sent to the RF modulator and transmitter and to the correlators. 
 BASED RADAR SYSTEMS FACE FUNDAMENTAL CHALLENGES 4HE PERMISSIBLE OPTIONS  FOR THE VALUE OF SEVERAL PARAMETERS SUCH AS PULSE REPETITION FREQUENCY  ARE MORE RESTRICTED FOR 3"2 THAN FOR AIRBORNE SYSTEMS ,IKEWISE  THE HARDWARE ENVIRONMENT IMPOSES MORE RIGOROUS CONSTRAINTS ON IMPLEMENTATION  AND 3"2 SYSTEMS DO NOT ENJOY THE LUXURIES OF HANDS 
 A planar array is capable of steering the beam in two dimensions. In a spherical-coordinate system the two coordinates 6 and <(> define points on the surface of a unit hemisphere. As shown in Fig. 
 17.9 Such amethod would beextremely advantageous ifmultiple sets ofangular data were toberelayed. 3.Pulse methods are inherently more accurate than c-w methods since they involve either” counting” orthemeasurement oftime probably the most accurate types ofphysical measurements that can bemade. Furthermore, nodependence whatever isplaced on the linearity ofr-fmodulators, amplifiers, detectors, etc., incon- trast tothec-w methods where allsuch devices must beextremely linear and free from dk.tortion. 
 504- 507.  77. Austin, P. 
 An array of spiral elements makes a simple scanning antenna. It is  primarily useful in those applications where a broadband element is required and the power is  not too high. The entire assembly, including the spiral radiators and feed networks, but  possibly excluding the rotary joint, can be manufactured with printed circuit techniques. 
 This makes it .. more conve­ nient to operate the radar at a remote site, and permits the outputs from many radars to be  communicated economically to a central control" point.  It should be noted that the adaptive thresholding of the automatic detector can cause a  worsening of the range-resolution._B.y analggy_~o the angular.J1!~9Jµti~n the angk  coordinate88 it wo~ seem a priori that tw_o_t;!rgets might be resolved in range if their  separation is abou~)>fthe pulse width. 
 GPR systems that transmit an impulse and receive the  reflected signal from the target using a sampling receiver can be considered to operate in  the time domain. GPR systems that transmit individual frequencies in a sequential man - ner and receive the reflected signal from the target using a frequency conversion receiver  can be considered to operate in the frequency domain. The latter systems often recon - struct the downconverted frequencies to recover a time-domain replica of the signal. 
 Both cases of apparent motion can result in 2CMV detection, but they obviously differ greatly in terms of meaning. Investigation of the state-of-the-art in SAR image processing indicates that differentiating between these two general cases is a problem that has not been well addressed. Algorithms that mitigate speckle noise effects well and distinguishing between actual motion and misregistration can lead to better change detection. 
 Another rolled parallel-plate scanning antenna, similar tothe type described inSec. 9“15inthe respect ofhaving asingle rotary waveguide feed, and also capable ofrapid scan, has been developed. The equiva- ~Moving waveguide horn CyhnderQ-- –-g elements\ forroll\ ‘P\@> >. 
 Figure 10.46 shows thevariation insize ofa pulse transformer with power output. Asinthe case ofpulse networks, FIG. 10.46.—Pulse transformers, the size and weight ofapulse transformer depends not only upon the pulse power tobehandled, but also upon the~ulse length and therepeti- tion rate. 
 (/2):/. 2!$!2   Óä°x OF MINUTES  BUT A LONG #)4 OF PERHAPS n S IS REQUIRED IN ORDER TO SEPARATE THE SHIP  ECHOES FROM THE SEA CLUTTER IN THE DOPPLER SPECTRUM $URING THIS TIME  4ASK S REQUIRE 
 (5.3).  Frequency agility, as described here for the reduction of glint, applies to the monopulse  tracking radar. It also reduces the glint in a conical scan or a sequentia.1-)obing radar. 
 Jasik (ed.),  Mc(iraw-flill Rook Company. New York, 1961.  123. 
 The much larger variation at s 0 apparently results from  the larger effect at vertical of the soil and consequently its moisture content. The  rapid 12 dB swing between May 25 and June 1 results from drying of the soil. Even  at 50°, where attenuation through the canopy masks the soil effect, the seasonal  variation exceeds 8 dB. 
 0.6 Transmit 1 dB/V 4°/VPhase, deg 5.0 4.0 4.6 6.0Size, in3 4.0 2.4 2.9 0.25 0.7weight, OZ 4.0 2.4 3.6 N.A. 0.7 Receive 1 dB/V 2°/V . 5.4 TRANSMITTERSYSTEMDESIGN Solid-state amplifiers are usually used in space-combined configurations, corporate-combined configurations, or a hybrid combination of the two. 
 (10) 54. Sensors 2019 ,19, 213 After the cross-correlation of two sub-view images is computed and the position of the correlation peak is searched, the estimated value of the offset Δˆfd,ijbetween two sub-view images can be obtained, then Δˆfd,ijis taken into (9) to estimate the errors of the Doppler parameters by the least squares principle./bracketleftBigg ˆedr 3 2ˆe3rd/bracketrightBigg =/parenleftBig TT acTac/parenrightBig−1 TTacΔˆf. (11) In practice, since the sub-view images are defocused and the defocus conditions of the different sub-view images are not exactly the same, there is certain error in the position of correlation peak of the sub-view image, so the MAM methods often require multiple iterations to achieve better estimate accuracy. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°ÈÎ #LOUD3AT ,AUNCHED IN !PRIL   #LOUD3AT INCLUDES AS ITS PRIMARY PAYLOAD  THE #LOUD 0ROFILING 2ADAR #02  #LOUD3AT FLIES IN A SUN 
 The sensitivity of a NLFM waveform to doppler shift can be seen in Figure 8.13,  which shows the matched filter output for a sine-based NLFM waveform in the pres - ence of doppler shift. The ambiguity function of a NLFM sine-based waveform is shown in Figure 8.14.  It can be noted that this ambiguity function is more thumbtack-like in nature than for  an LFM waveform, indicating that this waveform is more doppler sensitive than the  LFM waveform. 
 Also the power is usually not uniform over the operat-  ing band of the device. Thus, for one reason or another, the transmitted power may be other  than the design value. To allow for this, a loss factor may be introduced. 
 Radar System Engineeri ng Chapter 8 – Pulse Radar  64       Figure 8.20  Echoes of neighboring targets: left: before the compression, right: after the  compression.     Figure 8.21  Typical block diagram for Radar with FM pulse compression.   All filters with frequency dependent delay times are suitable for use as compression filters. 
 76-80.  December. 1968. 
 SIS MUST HAVE SUFFICIENTLY LOW SIDELOBES WHEN TRANSFORMS ARE TO BE APPLIED DIRECTLY TO HIGH DYNAMIC RANGE DATA 4HE BASIC STEPS OF RANGE  AZIMUTH  AND DOPPLER ANALYSIS ARE NOT THE ONLY STAGES OF  SIGNAL PROCESSING !S EXPLAINED IN 3ECTION   (& SKYWAVE RADAR SIGNALS ARE SUBJECT   &)'52%   .ONCOHERENTLY AVERAGED POWER SPECTRA FROM THREE CONTIGUOUS TIME INTERVALS  PLOTTED WITH  AN OFFSET FOR CLARITY 4HE TARGET LIES WELL OUTSIDE THE CLUTTER REGION WHERE THE "RAGG LINES ARE CLEARLY VISIBLE  SO  THE SIGNAL 
 A.: "Aerials for Metre and Decimetre Wave-lengths," Cambridge University Press.  London. 1949. 
 Conf. on Acoustics , Speech, and Signal Processing 2006 ,  ICASSP 2006, Toulouse, France, May 2006. 189. 
 101-110, 19S7. RADAR TRANSMITTERS 221  10. Beaver. 
 resolution isolates the individual scattering centers and therefore eliminates the glint problem.  With aircraft targets an effective pulse width of several nanoseconds (less ttiarl a riletcr range-  resollttion) can resolve the individual scatterers. Once the scatterers are resolved in rangc, an  angle measurement can be obtained on each one by use of monopulse. 
 DIMENSIONAL ARRAYS  UP TO  M HIGH AND  M WIDE IN THE CASE OF THE 3OVIET RADARS !T LOW ELEVATION ANGLES  THE ANTENNA PATTERN IS STRONGLY INFLUENCED BY THE ELECTRI 
 These factors are applied whenever the  target is not at the peak of a beam. Propagation factors customarily include the effects of multipath, diffraction, and  refraction, with atmospheric absorption effects included in the loss terms. As with a  monostatic radar, bistatic radar propagation requires a suitable path from the transmit - ter to the target and the target to the receiver. 
 Because of their poor stability and noisy transmissions, magnetrons  are limited in the amount of MTI Improvement Factor they can achieve to about 30 or  perhaps 40 dB. Many radar applications require greater MTI Improvement Factors.  Some radars also require the use of pulse-compression waveforms to obtain the reso - lution of a short pulse with the energy of a long pulse. 
 Skolnik (ed.), McGraw-  Hill Book Co., New York, 1970.  6. Barlow, E. 
 IT-3,  pp. 10-18, March, 1957.  24. 
 113. K. L. 
 revised the paper. Funding: This research was funded by [National Natural Science Foundation of China] grant number [61472324, 61771369] And The APC was funded by [61472324]. Acknowledgments: The authors would like to thank the journal manager, the handling editor, and the anonymous reviewers for their valuable and helpful comments. 
 An attack on the corner  problem has been suggested by Sikta et al.46 14.4 RCS MEASUREMENT TECHNIQUES RCS measurements may be required for any of several reasons, ranging from scientific  inquiry to verification of compliance with product specifications. There are no formal  standards governing instrumentation and measurement methods, but informal stan - dards of good measurement practice have been recognized for decades. Depending  on the size of the test object, the frequencies to be used, and other test requirements,  measurements may be made in indoor test facilities or on outdoor ranges. 
 (Courtesy of Varian Associ- ates.) these reasons, high-power TWT development lagged that of klystrons and is still more expensive. By 1963, however, Varian had produced multimegawatt pulsed TWTs using the cloverleaf circuit, as shown in Fig. 4.9,29 a structure that can be made heavy and rugged enough to handle power comparable with that of klystrons. 
 23  5.1 Measurement Accuracy and Sine Wave Oscillations ...................................................... 23  5.2 Accuracy and Range Measurement ................................................................................. 24  5.3 Range Resolution of Two Neighbouring Targets ............................................................ 
 ITY MAGNITUDE ONLY  IE   F2 MIN    ;MAX64 MAX CLOSING  64 MAX OPENING    6G=  K  AND RELY ON  DETECTIONS IN MULTIPLE 02&S DURING THE TIME ON TARGET TO RESOLVE THE SIGN AMBIGUITY IN  DOPPLER 4HESE RADARS CAN BE DESCRIBED AS  HIGH 
 (a)Two dipoles, mean height 220ft.(b)One dipole at90ft.(c)Ratio of(a)to(b) onanarbitrary scale.bymaking use ofthe lobe pattern of the receiving antennas. Figure 6.16 shows the vertical pattern produced bytwo receiving antennas, respec- tively at220 and 90ftabove ground. Ifone compares the signals received inthese two antennas asafunction of angle ofelevation, oneobtains acurve shown dotted inFig. 
 Neglecting the earth’s curvature, thetime tatwhich anindex ofconstant height hshould appear onanindividual sweep isdefined bytheequation h= Rsin4=~t sin& or2ht=—csin6’ where Risslant range, @iselevation angle, and cthe velocity oflight. The timing can most easily bedone bymeans ofalinear-sawtooth delay circuit. Avoltage proportional tosin@isused asthesupply potential forthe sawtooth generator. 
 PLER RADAR HAS A BETTER CHANCE  BUT IT HAS PROBLEMS OF ITS OWN BECAUSE OF THE FOLDOVER OF THE CLUTTER THAT MIGHT OCCUPY A LARGE RANGE EXTENT #OHERENT DOPPLER PROCESSORS MIGHT REQUIRE RELATIVELY LARGE AMOUNTS OF PULSES EG   MORE THAN    WHICH MUST BE  TRANSMITTED AT A STABLE FREQUENCY  AND 02& ! RESPONSIVE  JAMMER COULD MEASURE THE FREQUENCY OF THE FIRST TRANSMITTED PULSE AND THEN CENTER THE JAMMER TO SPOT 
 PREDICTED  EDGE 
 However, the axis of the ellipse is tilted at an angle to both the time and frequency axes. This . 418 INTRODUCTION TO RADAR SYSTEMS  8 \IT -T  Va  T Figure 11.12 Ambiguity diagram for a single frequency­ modulated pulse. 
 HORIZON RADAR WITH A STATISTICAL  IONOSPHERIC MODEL v )%%% 4RANS 3IG 0ROC  VOL   PP n  .OVEMBER   ' 7 0ULFORD  h/4(2 MULTIPATH TRACKING WITH UNCERTAIN COORDINATE REGISTRATION v  )%%% 4RANS  !%3  VOL   PP n    3 * !NDERSON  & * -EI  AND * 0EINAN  h%NHANCED /4(2 SHIP DETECTION VIA DUAL FREQUENCY  OPERATION v 0ROC #HINA )NSTITUTE OF %LECTRONICS )NT #ONF ON 2ADAR  "EIJING  /CTOBER   ' & %ARL AND " $ 7ARD  h&REQUENCY MANAGEMENT SUPPORT FOR REMOTE SEA 
 Ir~tc~r~rnt~ott(~l Cor!/i~rer~c~> R ADA R-77, pp. 559- 563, IEE (London) Conf.  P~thl. 
 ABLE PERFORMANCE %XAMPLES OF AN , BAND TWO 
 TION 7HEN THE RADAR ECHOES FROM LAND  SEA  OR WEATHER CLUTTER ARE GREATER THAN THE RECEIVER NOISE  THE RADAR EQUATION HAS TO BE MODIFIED TO ACCOUNT FOR CLUTTER BEING THE LIMITATION TO .   !. ).42/$5#4)/. !.$ /6%26)%7 /& 2!$!2   £°£Î DETECTION RATHER THAN RECEIVER NOISE )T CAN HAPPEN THAT THE DETECTION CAPABILITY OF A RADAR  MIGHT BE LIMITED BY CLUTTER IN SOME REGIONS OF ITS COVERAGE AND BE LIMITED BY RECEIVER NOISE IN OTHER REGIONS 4HIS CAN RESULT IN TWO DIFFERENT SETS OF RADAR CHARACTERISTICS  ONE OPTIMIZED FOR NOISE AND THE OTHER OPTIMIZED FOR CLUTTER AND COMPROMISES USUALLY HAVE TO BE MADE IN RADAR DESIGN ! DIFFERENT TYPE OF RADAR EQUATION IS ALSO REQUIRED WHEN THE RADAR CAPABILITY IS LIMITED BY HOSTILE NOISE JAMMING £°xÊ , ,Ê, 
 Thelobingofthe elevation patternduetoground reflections resultsinwiderelevation nullsatthelower frequencies andcancauselongfadetimesofthetargetsignals.Theelevation angleofthefirst multipath lobevariesinversely withfrequency (Sec.12.2),sothatlow-altitude coverage is moredifficult toachieveatthelowerfrequencies. Inspiteoflimitations, thelowerfrequencies arcattractive whenlowcostandlongrangearcmoreimportant thanotherfactors. 14.4HEIGHT-FINDER AND3DRADARS Inmanyapplications aknowledge oftargetheightmightnotbeneeded.Anobvious example iswherethetargetisknowntolieonthesurfaceoftheearth,anditslocation isgivenbythe rangeandazimuth coordinates. 
 DUCT SUCH A TEST MAY BE UNACCEPTABLE AT OTHERS IN THIS CASE  A MICROWAVE DELAY LINE CAN BE EMPLOYED TO FEED A DELAYED SAMPLE OF THE TRANSMITTER PULSE INTO THE RECEIVER !LL SOURCES OF INSTABILITY ARE INCLUDED IN THIS SINGLE MEASUREMENT EXCEPT FOR ANY CONTRIBUTORS OUTSIDE THE DELAY 
 Wuhan city has experienced rapid economic growth since the China’s reform and opening up policy in 1979. It has become a megacity with a population in excess of 10 million. 214. 
 EMPIRICAL ELECTRON DENSITY PROFILES  OR BETTER  STORED hSNAPSHOTSv OF THE IONOSPHERE GENERATED BY AN 24)- !LTERNATIVELY  ANALYTIC RAY 
 Target Cindicates anintermediate case. The display issurprisingly easy tointerpret after ashort period of observation. 6.8. 
 Unexpected  outputs can range from unintended signals related to the  desired pulse (such as harmonics, sub -harmonics, image  mixing products, etc.), as well as spurious outputs unrelated to  the desired pulse, such as radiation of internal local  oscillators, coupling from digital clocks, spurious oscillations  within RF circuitry, pulse errors, and so forth   In the modern wor ld of "software defined" radar, modulated  pulses, chirps, and other waveforms are usually  not generated   with traditional analog circuitry, but with  Digital Signal  Processors  (DSP) and Direct Digital Synthesis (DDS)  techniques . These digital techniques  gene rate complicated  signals directly at intermediate frequencies ( IF) or RF  frequencies. The signals  only become analog when the  synthesized digital data is passed  through a digital -to-analog  (D/A) converter. 
 The experimentally found blip-scan ratio curves are subject to many  limitations, but it represents one of the few methods for evaluating the performance of an  actual radar equipment against real targets under somewhat controlled conditions.  THERADAR EQUATION 63 whereHill"'=maximum radarrange, III (i=antcnna gain .4=antenna aperture, 1112 I'a=antenna efficiency /I=numberofhitsintegrated Ej(/l)=integration efficiency (lessthanunity) LJ=systemlosses(greater thanunity)notincluded inotherparameters fT=radarcrosssectionoftarget,m2 Fn=noisefigure k=Boltzmann's constant =1.38x10-23J/deg 70=standard temperature =290K B=receiver bandwidth, Hz r=pulsewidth.s .If'=pulserepetition frequency, Hz (51N)\=signal-to-noise ratiorequired atreceiveroutput(basedonsingle-hit detection) Thisequation canalsohewrittenintermsofenergyratherthanpower.Theenergyinthe transmitted pulseisEr=Pa\!/~=PIrandthesignal-to-noise powerratio(SIN)Icanbe replaced bythesignal-to-noise energyratio(EIN0)1,whereE=Siristheenergyinthe received signal.andNo=NIBisthenoisepowerperunitbandwidth, orthenoiseenergy.Also notethatBr~1,andToFn=~isdefinedasthesystemnoisetemperature. Thentheradar equation becomes R4=ErGAPalJ1lEi(l1) max(4rr)2kI;(EIN o)1Ls(2.55) Although Eq.(2.55)wasderived forarectangular pulse,itcanbeappliedtootherwaveforms aswell,provided matched-filter detection isemployed. 
 807-808, May. 1966.  23. 
 At an angk  <J>, the contribution from a particular point on the aperture will be advanced or retarded in  phase by 21r(z/l) sin</> radians. Each of these contributions is weighted by the factor A(z). The  field intensity is the integral of these individual contributions across the face of the aperture. 
 (ALL     2 ' ,YONS   5NDERSTANDING $IGITAL 3IGNAL 0ROCESSING   ND %D  5PPER 3ADDLE 2IVER  .*  0RENTICE (ALL     * / #OLEMAN  h-ULTI 
 Even more important, it  allows the student to research the literature and to be a bit more creative than is possible by  simply solving standard problems.  A book of this type which cover~ a wide variety of topics cannot be written in isolation. It  would not have been possible.withoutthe many contributions on radar that have appeared in  the open literature and which have been used here as the basic source· material. 
 (ed.): " Propagation of Short Radio Waves," MIT Radiation Laboratory Series, vol. 13.  pp. 
 Since the probability that one ofthese will coincide with apulse onthe suppressor grid isn7,1the total number ofpulses triggering V,each second is2n’rz. This istobecompared with the number nofinter- fering signals originally present, theratio ofimprovement being n/2n3r2 =l/2n2r2. If,forexample, r=1psec and n=10,000, this ratio is5000. 
 One example isvegetation, which covers most ofthe land over which anairplane islikely tofly. Another isthediffuse return from irregularities onthe surface ofthesea. Let usexamine briefly the processes involved inthe reception ofa radar signal from alayer ofscatterers, such asthe layer ofvegetation onthe ground. 
 149. H. Kushel, “VHF/UHF. 
 In this context, it is the bandwidth of the received signal that is  important, rather than that of the transmitted wavelet. The material acts as a low pass  filter, which modifies the transmitted spectrum in accordance with the electrical prop - erties of the propagating medium. There are some applications of GPR, such as road  layer thickness measurement, where the feature of interest is a single interface. 
 OF 
 With the "greater-of" technique the  oss is itlcreased to I. l dB.75)  Typically the number of taps used in a cell-averaging CFAR might vary from 16 to 20.  The CFAR may be thought of as using the outputs of the sampled cells to estimate the  unknown amplitude of the background noise or clutter. 
 A receiving system can be represented as a cascade of two-port transducers, preceded by a source (the antenna) and terminated by a load. [However, in the discussion of system noise temperature, only those parts of the receiver that precede the detector (demodulator) are of significance, for the noise level at that point determines the signal-to-noise ratio for signal-detection-calculation purposes.] Noise may arise at any and all points in this cascade, so that the noise level changes from point to point. The important quantity is the output noise power Pno. 
 For instrumentation radar, where  the time of a tracking event is known, final calibration is performed just preceding the  event to minimize drift errors. 9.11 SUMMARY OF SOURCES OF ERROR Angle Measurement Errors.  An inventory of angle measurement errors is  given in  Table 9.2. 
 LOW SIDELOBE ARRAY  CONSISTING OF  SLOTTED WAVEGUIDES WITH OVER  SLOTS SEE &IGURE   -OUNTED ATOP THE AIRCRAFT FUSELAGE IN A ROTATING DOME  THE 3 
 T. L. Wilfong, D. 
 The difference in the phase  of the signals in adjacent elements is \I/ = 2n(d/A) sin 0, where 0 is the direction of the incoming  radiation. It is further assumed that the amplitudes and phases of the signals at each element  are weighted uniformly. Therefore the amplitudes of the voltages in each element are the same  and, for convenience, will be taken to be unity. 
 The useoftwo tubes intheway described inthenext paragraph ismore satisfactory. Two such switches can beused inparallel toalternate signals from two sources, asshown inFig. 13”28. 
 For example, for a 0.5 probability of detection and  a 10-3 probability of false alarm, the loss is LO dB for M = 100, 2.2 dB for M = 20, and 7 dB  for M = 10.73 In essence the Dicke fix (that uses wideband limiting) samples the adjacent  resolution cells in the frequency, domain, as compared to the cell·averaging CF AR that  samples the background in the adjacent resolution cells in the time domain.  When the product of the bandwidth Band the pulse width t is greater than unity, as in a  pulse compression radar, the loss is determined by the product M Bt rather than M. Thus, a  loss of LO dB corresponds to M Br = · 100. 
 Radar System Parameter. Parameters V alue Time width 24 us Band width 40 MHz Pulse repetition frequency 2500 Hz Scanning area 45◦~135◦ Coherent pulses 128 Range gate number 4096 The DBS imaging results using different algorithms (i.e., the conventional FFT-based, Relax-based, APES-based and the proposed KA-DBS algorithm) are given in Figure 8. In KA-DBS, the predicted forward and backward pulse number is half of the pulse number in one CPI. 
 maybeconsidered asabroadband directional couplerwithacoupling ratioof3dB.Inthe transmit condition (Fig.9.6a)powerisdividedequallyintoeachwaveguide bythefirstshort­ slothybridjunction. BothTRtubesbreakdownandreflecttheincidentpowerouttheantenna armasshown.Theshort-slot hybridhastheproperty thateachtimetheenergypassesthrough theslotineitherdirection, itsphaseisadvanced 90°.Therefore, theenergymusttravelas indicated bythesolidlines.Anyenergywhichleaksthrough theTRtubes(shownbythe dashedlines)isdirected tothearmwiththematched dummyloadandnottothereceiver. In addition totheattenuation provided bytheTRtubes,thehybridjunctions provideanaddi­ tional20to30dBofisolation. 
 (13.17) varies as the fourth power of the frequency. A radar operating at L band  (1.3 GHz), for example, might experience about 34 dB less precipitation cluttcr...than a radar at  X band (9 GHz). Thus when precipitation is of concern, the lower frequencies are to be  preferred. 
 In  a recirculating delay-line integrator, e-.., is the attenuation around the loop. ln an RC  low-pass filter y = Tp/RC, where Tp is the pulse repetition period and RC is the filter time  constant.  In order to find the signal-to .. 
 Ontheotherhand,astowscanratemeansalongertime hetween looksatthetarget.Scanratesofpractical searchradarsvaryfrom1to60rpm,5or 6rpmbeingtypicalforthelong-range surveillance ofaircraft. Thecoverage ofasimplefanbeamisusuallyinadequate fortargetsathighaltitudes close totheradar.Thesimplefan-beam antenna radiates verylittleofitsenergyinthisdirection. However. 
 "Radar Systems Analysis," Prenticc-Ilall, inc., Ncw Jcrscy, 1964.  3. James, H. 
 As target speeds increase, it is increasingly difficult for an operator to perform at the  necessary levels of efficiency over a sustained period of time, and automatic tracking becomes  a necessity. Indeed, there are many tracking applications where an operator has no place, as in  a homing missile or in a small space vehicle.  The technique for automatically tracking in range is based on the split range gate. 
 ORDER SPECTRAL FILLING AROUND THE LINES THAT WERE MENTIONED IN THE EARLIER SECTION ON (& SEA CLUTTER /N THE OTHER HAND  THE VARIOUS INTEGRAL FORMULATIONS REFERENCED ABOVE USUALLY BEGIN  WITH A VERY GENERAL EXPRESSION FOR THE FIELDS SCATTERED FROM THE SEA SURFACE  WHICH ARE SQUARED AND ENSEMBLE 
 The changescanhaveaprofound effectonradarperformance. Theindividual resolved spikescan causefalsealarms.Raisingthereceiverthreshold leveltoreducethefalsealarmscanresult inasignificant lossinsensitivity todesiredtargets.Thisnegatesthebenefitoftheincreased signal-to-clutter ratio achieved byhighresolution asexpressed byEq.(13.8)forthedetection oftargetsinclutter.(Aswillbediscussed inSec.13.4therearetechniques forreceiver detector-design thatcanavoid ~uchofthisloss.)Acorollary consequence ofhighresolution isachangeintheprobability densityfunction oftheseaecho,asdescribed next. Probability densityfunction ofsea.clutter.Theamplitude ofseaclutterischaracterized by statistical fluctuations which,must:be described.in termsoftheprobability densityfunction. 
 A transmitter is a  major part of a radar system; hence, its size, cost, reliability, and maintainability can  significantly affect the size, cost, reliability, and maintainability of the radar system of which it  is a part. Not only does the transmitter represent a significant fraction of the initial cost of a  radar system, but it can often take a large share of the operating costs because of the prime  power and the needs of maintenance. The classical radar range equation (Chap. 
  ! NEXT  GENERATION SOLID 
 Naturally, it  is not surprising that such a desirable ambiguity diagram is not possible. The fundamental  properties of the arribiguity function prohibit this type of idealized behavior. The two chief  restrictions are that the rnaxinium height of the IX I2 function be (2~)~ and that the volume  under the surface be finite and equal (2E)2. 
 4.1 1 with the weights given by  Eq. (4.13) is  The Fourier transform of the impulse response is the frequency response function  The magnitude of the frequency response function is the amplitude passband characteristic of  the filter. Therefore  N  &2rt(i- 1 )IfT-klNI = I I sin [nN(.jT - k/N)]  I Hk(.f) 1 = 1  i= I sin [n(,fr - k/N)]  By analogy to the discussion of the array antenna in Sec. 
 (From Davis and Cohen, 125 courteS}' Electronics a,ul  MIT Lincoln Laboratory.) ·  55-ft-diameter radome shown in Fig. 7.29 is designed so that the plastic flanges between  the panels take the load while the plastic panels act as thin diaphragms which merely transmit  wind-pressure loads to the framework to which they are attached. The supporting framework  can also be of steel or aluminum members rather than plastic. 
 17, pp. 508–514, 1978. 38. 
 A 10 ft range cell size is often used  to match the smallest vehicle of interest and to reduce background clutter. Ground  moving target recognition may require 0.25 ft resolution. Antenna illumination  must be ground stabilized since the aircraft will engage in both intentional and  unintentional maneuvers.94 Ground Moving Target Thresholding. 
 SOR ARCHITECTURE IS NOT NECESSARILY REQUIRED !LSO  &0'! DESIGNS TEND TO BE AIMED AT A PARTICULAR FAMILY OF DEVICES AND TAKE FULL ADVANTAGE OF THE RESOURCES PROVIDED BY THAT FAMILY (ARDWARE VENDORS ARE CONSTANTLY INTRODUCING NEW PRODUCTS  INVARIABLY INCORPORATING NEW AND IMPROVED CAPABILITIES /VER TIME  THE OLDER DEVICES BECOME OBSOLETE AND NEED TO BE REPLACED DURING A  TECHNOLOGY REFRESH CYCLE 7HEN A TECHNOL 
 47. McMalion. F. 
 248. Oct. 30,  1952. 
 At the ground station, the data line demodulator recovered the radar sensor stalo and the radar return signal. The recovered synchronously demodulated video radar signal was then converted into digital form by the radar data recorder and formatter subsystem. Upon conversion, the signal was buffered and recorded by a high-density magnetic tape recorder. 
 Weiss, H. G.: The Haystack Microwave Research Facility, Spectn1111, vol. 2, pp. 
 June. 1971  16. A 11011 ymous: Introduction to Pulsed Crossed-Field Amplifiers, brochure published by Varian. 
 AES-12, pp.  405 408. May. 
 “Regulations regarding the minimum requirements and test conditions for radar equipment used  for River Rhine and inland waterways,” Central Commission for the Navigation on the River  Rhine, Strasbourg, 1989. 15. “Maritime navigation and radiocommunication equipment and systems—Radar for craft  not in compliance with IMO SOLAS Chapter V,” IEC 62252, International Electrotechnical  Commission, Geneva, 2004. 
 'Tliravcs. J.: A Yitw Stahililcd S.A.H. Acrii~l. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar.  METEOROLOGICAL RADAR  19.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 Wilson and Brandes114 give a comprehensive treatment of how radar and rain- gauge data can be used to complement one another in measurements of precipitation  over large areas. 
 Center of  torus \ _l_i  ..... ' \  ('"' of teed  positions Generoting  porobolo  Figure 7.16 Principle of the parabolic-torus antenna. RADAR ANTENNAS 247  The advantage of the parabolic torus is that it provides an economical method for rapidly  scanning the beam of a physically large antenna aperture over.a relatively wide scan angle with  110 deterioration of the pattern over this angle of scan. 
 QUALITY MICROWAV E DIELECTRIC MATERIAL  MUST BE INTEGRAL TO THE MICROWAVE ELECTRICAL AND MECHANICAL DESIGN OF THE MODULE !TTENTION TO THE COEFFICIENT OF THERMAL EXPANSION AND MANUFACTURABILITY ISSUES WILL IMPACT THE CHOICE OF USABLE MATERIALS 42 MODULES ALSO GENERAL LY REQUIRE AS MANY AS  n CONTROL OR BIAS CONNECTIONS IN ORDER TO INTERFACE WITH AMPLIFIERS  CONTROL CIRCUITRY  AND PHASE SHIFTERS 4HE INTERCONNECTION DENSITY  ESPECIALLY AT HIGHER FREQUENCIES  CAN BECOME A PACKAGING DESIGN CHALLENGE !T FREQUENCIES ABOVE  '(Z  THE USE OF CON 
 OF 
 Con-  versely, a loud-speaker wired to the output of a radar  set produces a particularly obnoxious noise, the speech~  coil of the speaker vainly trying to follow the sharp  impacts and cut-offs of the square-wave pulses.  So now let us have a look at our complete radar chain  of apparatus. We need a modulator (‘Mod’) to produce  a nice, sharp-edged pulse. 
   3!2 SYSTEM v IN 0ROCEEDINGS OF %53!2   $RESDEN  'ERMANY  6$% 6ERLAG     7 - "OERNER  ( -OTT  % ,UNEBURG  # ,IVINGSTONE  " "RISCO  2 * "ROWN  AND * 3 0ATERSON   h0OLARIMETRY IN RADAR REMOTE SENSING BASIC AND APPLIED CONCEPTS v IN  0RINCIPLES AND !PPLICATIONS OF  )MAGING 2ADAR  & - (ENDERSON AND ! * ,EWIS EDS   .EW 9ORK *OHN 7ILEY  3ONS  )NC     , 'RAHAM  h3YNTHETIC INTERFEROMETERS FOR TOPOGRAPHIC MAPPING v  0ROC )%%%  VOL   PP n     2 'ENS AND *  VAN'ENDEREN  h2EVIEW ARTICLE 3!2 INTERFEROMETRYISSUES  TECHNIQUES  APPLICA 
 The array factor has also been called the space . 282 INTRODUCTION TO RADAR SYSTEMS  factor. Grating lobes caused by a widely spaced array may therefore be eliminated with  .. 
 Dillard26 © IEEE 1977 ) ch07.indd   16 12/17/07   2:13:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 B. R.: The Geographical and Height Distribution of the Gradient of Refractive Index, Proc.  IRE. 
 Conf. on Interact. Info. 
 Phase shifters based on diode devices can be  of relatively high power and low loss, and can be switched rapidly from one phase state to  another. They are relatively insensitive to changes in temperature, they can operate with low  control power, and are compact in size. They lend themselves well to microwave integrated  circuit construction, and are capable of being used over the entire range of frequencies of  interest to radar although their losses are generally less and their power handling is generally  higher at the lower frequencies. 
 TRAST IF IT WERE NOT COMPENSATED BY APPLYING A CORRESPONDING POST DETECTION INTEGRATION 0$)  FOR EACH ANGLE  AS SHOWN IN &IGURE  -ULTIPLE FREQUENCY LOOKS ARE USED TO REDUCE SPECKLE IN THE IMAGE AND SO SEVERAL  DIFFERENT FREQUENCIES ARE 0$)ED 4HE #0) IS THE PRESUM RATIO TIMES THE NUMBER OF FILTER SAMPLES n IS TYPICAL  %ACH #0) MAY HAVE MINOR CHANGES IN THE 02& TO SIM 
 Solid circles apply to average  values ?- 20" around broadside, x's apply to  the average of the 4 20" sector about the  head and tile k20" sector about the tail.  (.4fier Holyhton arld Smith.93)  RADAR CLUTIER 509 Table13.3Radarcrosssectionsofbirds91 BirdFrequency bandMeanradar crosssectionIcm2)Median radar crosssection(cm2) (jracklc Srarrow Pigeonx S UHF X S UHF X S UHF16 25 0.57 1.6 14 0.02 15 XO II6.9 12 0.45 0.8 II 0.02 6.4 32 8.0 described statistically. Thereissomeevidence toindicate thattheprobability densityfunction fortheradarcrosssectionof(orreceived powerfrom)asinglebirdinflightislog-normal. 
 237–252, March 1973. 85. B. 
 The refocusing results of ship03 are presented in Figure 11. The result of the proposed method is better than the DCT and PGA method results in Figure 11d. The left side regions of the ship are obviously well-focused and become clear in Figure 11d. 
 II in ASR Warwick Aircraft, Technical Note No. 140, Radio Department RAE, 21 August 1943 (TNA AIR 6/12340) [12] Performance of ASV Mk. II in Hampden Aircraft, CCDU Report 42/43, August 1943 (TNA AIR 65/37) [13] A.S.V. 
   2!$!2 2%#%)6%23   È°Îx $# /FFSET 3MALL SIGNALS AND RECEIVER NOISE CAN BE DISTORTED BY AN OFFSET IN  THE MEAN VALUE OF THE !$ CONVERTER OUTPUT UNLESS THE DOPPLER FILTER SUPPRESSES THIS  COMPONENT &ALSE 
 Most of  the interest in AMTI, however, is for airborne radar.58  Compensation for clutter doppler shift. When the clutter doppler frequency is other than at  de, the null of the frequency response of the MTI processor must be shifted accordingly. The  effect on the improvement factor when the center of the clutter doppler frequency is shifted by  an amount./~ is shown in Fig. 
 MATION IS THAT THE CURRENT FLOWING AT EACH POINT IN A LOCALLY CURVED OR ROUGH  SURFACE  IS THE SAME AS WOULD FLOW IN THE SAME SURFACE IF IT WERE FLAT AND ORIENTED TANGENT TO THE ACTUAL SURFACE 4HIS ASSUMPTION PERMITS CONSTRUCTION OF SCATTERED FIELDS BY ASSUMING THAT THE CURRENT OVER A ROUGH PLANE SURFACE HAS THE SAME MAGNITUDE AS IF THE SURFACE WERE SMOOTH  BUT WITH PHASE PERTURBATIONS SET BY THE DIFFERING DISTANCES OF INDIVIDUAL  &)'52%     .ORMAL 
 24.3 TRANSMITTERS Most of the radar designs and missions require transmitter average power levels between 10 kW and 1 MW. Antennas are generally arrays of elements, and the common trend is to drive each element with a separate amplifier. This approach permits beam steering at a low level in the amplifier chain. 
 Figure 4.2 shows the unfolded spectrum (i.e., no spectral foldover from adjacent  PRF lines) in the case of horizontal motion of the radar platform, with a speed VR.  The clutter-free region is defined as that portion of the spectrum in which no ground  clutter can exist. (A clutter-free region usually does not exist with medium PRFs  due to doppler folding.) The sidelobe clutter region, 4 VR/l in width, contains ground  clutter power from the sidelobes of the antenna, although this clutter power may be  below the noise level in part of the region. 
 Scharf man, H.: Scattering from Dielectric Coated Spheres in the Region of the First Resonance, J.  Appl. Pltys .. 
 However, to understand the effect that the radar seeker's ability to measure the target's radar observables has on the performance of the missile (miss distance), a brief overview of guidance principles is presented here. Virtually all homing systems employ some form of proportional navigation (PN), although modern control theory (such as Kalman filtering) has been used extensively to optimize performance of later-generation systems. The important fact to note is that PN can be accomplished with angle-only measurements and can thus become a fallback mode even if range or doppler (range rate) informa- tion—required for advanced guidance techniques—is unobtainable. 
 TIAL IMPROVEMENTS IN SPURIOUS 
 and Siq11al l'mcessinq. Apr. 12 -14. 
 W.: Radar Technology Applied to Air Traffic Control..IEEE Trutrs., vol. COM-?I.  pp. 
 -ARTINEZ  % 0OTTIER  AND 3 2 #LOUDE  h3TATISTICAL ASSESSMENT OF %IGENVECTOR 
 Other consequences follow in turn: the wide  transmitted pulse used with pulse compression blinds the radar at short ranges, so a  “fill-in” pulse must also be transmitted and processed. To prevent points of strong clut - ter from masking small moving targets, the signal processor must achieve low pulse  compression time sidelobes and high clutter cancellation ratio. As a result, it is much  easier to design a solid-state transmitter as part of a new system than it is to retrofit one  into an old system that usually does not have all these features. 
 IEE Conference Publica­ tion no. 28, pp. 41-44. 
 There was an antenna  heater to prevent icing, and the transmitter and the receiver (to IF) were “upmast”  (integrated within the antenna turning unit.) The display was a 9 in (23 cm) cathode  ray tube plan position indicator. The similarities with systems being sold in the 21st  century are perhaps more surprising than the obvious differences. LIST OF MARITIME RADAR-RELATED  ABBREVIATIONS AIS Automatic Identification System AtoN Aid to Navigation CCRP Consistent Common Reference Point CMR Civil Marine Radar COG Course Over Ground CPA Closest Point of Approach EBL Electronic Bearing Line ECDIS Electronic Chart Display and Information System ENC Electronic Navigational Chart (The data for ECDIS) FTC Fast Time Constant (differentiator) GNSS  Global Navigation Satellite System GPS Global Positioning System gt Gross tonnage (metric tonnes) HL Heading Line IALA International Association of Lighthouse Authorities IBS Integrated Bridge System IEC International Electrotechnical Commission IMO International Maritime Organization ITU International Telecommunications Union MFD Multi-function Display PI Parallel Index line NT Radar  New Technology Radar (Marine term for coherent solid-state radars) nm Nautical mile ( = 1842 meters) SART Search and Rescue Transponder SOG Speed Over Ground SOTDMA  Self Organizing Time Division Multiple Access STW Speed Through the Water TCPA Time to Closest Point of Approach VTS Vessel Traffic Services UTC Universal Time Coordinated VRM Variable Range Marker ch22.indd   33 12/17/07   3:02:41 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Comparison ojtheTWO TypesofPulsers.—The basic circuit ofFig. 10.26 applies, ashas been shown, totwo types ofpulse generators. In one type asmall amount oftheenergy stored inacondenser isallowed to bedissipated intheload during each pulse. 
 Itisareciprocal deviceinthatthephaseshiftisthesameforbothdirections of propagation. Whenitwasintroduced, theReggia-Spencer phaseshifterhadahigherfigureof merit(defined asthedegreesofphaseshiftperdBofloss)thanprevious analogferritephase shifters, andwasmorecompact. Sincetherodofferriteislocatedatthecenteroftheguideout ofcontactwiththewalls,thereisnomeansfordissipation ofheatotherthanbyradiation. 
 .--~~-, 0-- Receiver Deloy-line  T= 1/prt Subtroctor  circuit  Figure 4.4 MTI receiver with delay-line canceler. Full·wove  rectifier . MTI AND PULSE DOPPLER RADAR 105  video. 
 ofplywood; and the copper-coated plywood reflector, 2by12ft,hinged tothe deck ofthehousing (Fig. 9.25). The reflector isahalf parabolic cylinder ofl-ft focal length, and isfed bythe 1l-ft by1.4-in. 
 WIDTH  + PULSES ARE SUMMED BATCHED  AND EITHER A  OR A  IS DECLARED  DEPENDING  ON WHETHER OR NOT THE BATCH IS LESS THAN A THRESHOLD  4 4HE LAST  . ZEROS AND ONES ARE &)'52%  !NGULAR ACCURACY FOR TWO PULSES SEPARATED BY  BEAMWIDTHS . 
 Reintjes. J. F., and G. 
 22. D. J. 
 Assume a doppler filter bank of n-pulse FIR filters and assume a process - ing dwell that consists of three CPIs. The CPIs must use different PRFs and may also  employ different RF frequencies. (The different RF frequencies change target RCS  statistics from Swerling 1 to Swerling 2, and thus less radar energy is required for high  probability of detection.) The CPIs must have (1) sufficient transmitted pulses so that  n returns (enough to fill an n-pulse filter) will be received from the most distant target  of interest and the most distant clutter and (2) one additional pulse to enable velocity  determination (more on this later). 
 target , positionJ (12.9)(b) Figure12.5{(I)Extension oflheradarhorizonductorefraction ofradarwavcshylhcatmosph~r~: (h) angularerrorcausedbyrefraction. thLradarcoverage (Fig.12.5a).Another effectistheintroduction oferrorsinthemeasurement ofelevation angle(Fig.12.5h).Bending, orrefraction, ofradarwavesintheatmosphere is causedbythevariation withaltitudeofthevelocityofpropagation. ortheilldexofI'el;·(/ctioll. 
 The image is still cognizable in the case of p=3. However, in Figure 13d for p=5, the scintillation-contaminated image is nearly unable to recognize. The image blur can be seen from the houses and trees in the middle of the scene. 
 Therefore, for a period of 2 microseconds a peak power of 200 kilowatts issupplied to the antenna, while for the remaining 1998 microseconds thetransmitter output is zero. Because average power is equal to peak power timesthe duty cycle, High peak power is desirable in order to produce a strong echo over the maximum range of the equipment. Low average power enables thetransmitter tubes and circuit components to be made smaller and morecompact. 
 The function of the  horizontal branches is to complete the magnetic circuit.  By introducing the applied magnetic field from within the waveguide via the single-turn  drive wire. the shorted-turn efTect that limits the switching speed of 1111' Reggia-SPL'IICC~ PII;ISC  shifter is eliminated. 
 Electron., (London), vol. 1, pp. 389-404, 1956. 
 BAND SIGNALS THAT CANNOT BE READILY CANCELLED  THROUGH LINEAR CANCELLATION TECHNIQUES  RESULTING IN SUSCEPTIBILITY TO JAMMERS )NTERMODULATION DISTORTION OCCURS THROUGHOUT THE RECEIVER CHAIN #ONSEQUENTLY  THE  RECEIVER WILL HAVE A SIGNIFICANTLY DIFFERENT INPUT INTERCEPT POINT  DEPENDING ON THE  SIGNAL FREQUENCY RELATIVE TO THE RADIO FREQUENCY 2&   )&  AND VIDEO FILTER BANDWIDTHS )T IS  THEREFORE  IMPORTANT TO DISTINGUISH BETWEEN THE REQUIREMENTS FOR IN 
 This is the type of decision  probably made (subconsciously) by a human operator on the basis of the information present  at the radar indicator. When the detection process is carried out automatically by electronic  means without the aid of an operator, the detection criterion cannot be left to chance and must  be carefully specified and built into the decision-making device by the radar designer.  In Chap. 
 Since the phenomenon occurs near the ground and oftentimes in very light or no precipitation, ground clutter mitigation is necessary. C band seems to be the preferred operational frequency for several reasons. First, a C-band antenna will be physically smaller than an S-band antenna for the same beamwidth, an important consideration for use near airports. 
 8 Common reflector surface materials for reduced wind resistance: ( a) tubing, ( b) expanded  metal, ( c) rectangular, ( d) double layer, and ( e) screen ch12.indd   11 12/17/07   2:31:13 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 
 Cases 3 and 4, described by Eq. (2.39b ),  are equivalent to m = 2 in the chi-square distribution. The ratio of the variance to the average  value of the cross section is equal tom-112 for the chi-square distribution. 
 SAR Acquisition and Data Processing A total of 17 repeat-pass TerraSAR X-band Stripmap images were collected (orbit no. 119, descending), with a spatial resolution of 3 m (3.29 m along azimuth, 2.64 m along range, average incidence angle of 26.4◦). These acquisitions covered the period from 17 June 2014 to 27 November 2015. 
 Through multi-angle image fusion, we can obtain more detailed information about the target, which improves the target detection and recognition ability of SAR images. SAR image matching fusion can be achieved quickly by imaging in a uniﬁed coordinate system. In order to maximize the use of the spectrum, it is necessary to make the interpolated spectrum as rectangular as possible. 
 Direction determi nation   Bearing   The direction to the target is determined by the directivity of  the antenna. Directivity, sometimes known as the directive  gain, is the ability of the antenna to concentrate the  transmitted energy in a particular direction. An antenna with  high directivity is also called a directive antenna. 
 Small steam engines and gas turbines areattractive because oftheir ease ofcontrol and flexibility. Further development would probably produce some worth-while small prime movers. 14.14. 
 1, pp. 191–205, January 2006. 168. 
 TRACKING RADAR  9.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 The major difference between noise and a target echo is that noise spikes exceeding the  threshold are random, but if a target is present, the threshold crossings are more regular.  One typical system simply counts the number of threshold crossings over the integration  period, and if crossings occur for more than half the number of times that the radar has  transmitted, a target is indicated as being present. If the radar pulse repetition frequency  is 300 Hz and the integration time is 0.1 s, the radar will observe 30 threshold crossings  if there is a strong and steady target. 
  3.2  F     04  
 The persistence of these sea-clutter spikes makes difficult the detection of  small targets. such as buoys and small boats. A single "snapshot" of a PPI would not likely  differentiate the echo of a small target from that of the sea spikes. 
 10.6 changing difficulties arise asystematic attack ispossible. The important conclusions ofthis study aregiven here. Mode changes areoftwo types. 
 15.11  Signal-to-Clutter Ratio Improvement (I SCR)  .........  15.11  Subclutter Visibilit y (SCV)  ..................................  15.13  Interclutter Visib ility (ICV)  ................................... 
 16.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 FIGURE   16. 27 90% range of pixel amplitude versus resolution FIGURE   16. 26 Angular patterns of the mean, upper decile, and lower decile of Skylab  scatterometer observations over North America during the summer season ( from Moore et al.,  University of Kansas Remote Sensing Laboratory Technical Report 243-12, 1975 ) ch16.indd   34 12/19/07   4:56:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 252-253, June, 1967.  96. Shelton, J. 
 (/2):/. 2!$!2   Óä°Ó£ -ODELS OF )ONOSPHERIC 2ADIOWAVE 0ROPAGATION  &ROM THE (& SKYWAVE RADAR PER 
 The block diagram of a monopulse Radar device is represented in Figure  13.8.  sum θ sum ψ sum θ+ψψψ θ θ difference  ψdifference  θ processing     Figure 13.8  Block diagram of a monopulse Radar device.  . 
  
 A  2.5° azimuth resolution is also required. All these performance figures are considered  to be peak errors, which can be assumed to mean 95% values, measured with stan - dardized point targets. The IMO performance standards recognize that the detection  performance of radars working within conditions of clutter will not necessarily give  the performance defined for clear conditions. 
  AIR 
 Unlike  the line-type modulator, the switch in the active-switch modulator controls both the  beginning and end of the pulse. Since the energy storage device is a capacitor, the  pulse can droop, something that can be prevented by extracting only a small fraction  of the stored energy from the capacitor. This requires a large capacitance, which may  be obtained with a collection of capacitors called a capacitor bank . 
 Baker, R. A. Hutchins, and C. 
 Thus there isalways afinite chance of getting ahigh noise peak. For example, theprobability that atagiven time Pisgreater than 5Po ise-5or0.0068. For the discussion that follows itisconvenient tosimplify the problem somewhat bydividing the time base into discrete intervals each l/CB long. 
 Wetzel, “HF sea scatter and ocean wave spectra,” presented at URSI Spring Meet., National  Academy of Sciences, Washington, April 1966. 101. A. 
 TRACING PROCEDURE v $34/ 4ECHNICAL 2EPORT   32, 
 Peak  transmitted powers are 700 W and 140 W. Mass and input power of the two radars are  450 kg and 330 kg and 384 W and 326 W. The only other instrument in the payload  is a microwave radiometer. 
 Mitchell: A Lightweight and Self-contained Airborne Navigational System, Proc. IRE, vol. 47,  pp. 
 Thus if the  gating pulse coincides with the pulses on the control  grid there is change in anode voltage, and the resulting  output form is controlled at those instants only by both  FIG. 18  FIG. 19  FIG. 
 ................................ ................................ .. 
 Indeed, when we come right down to  wavelengths only an inch or so in length we can employ  aerials and reflectors to beam the rays just as we should  beam light rays. There is a similarity even in appear-  ance, for the great bowl-shaped ‘dishes’ of wire-netting  and the metal parabaloids used as reflectors are like  giant searchlights. Something like the same ° optics’  apply, but, of course, we do not use radar waves as short  as light waves. 
 Increasing the size of a  magnetron, however, requires increasing the number of resonators. The greater the number of  resonators the more difficult the problem of mode separation. Since the mode separation in a  coaxial magnetron is controlled in the TEoll stabilizing cavity rather than in the resonator  area, the coaxial magnetron can operate stably with a large number of cavities. 
 However, the frequency difference must not be too large if  unambiguous measurements arc to be made. The selection of ~f represents a compromise  between the requirements of accuracy and ambiguity. Both accurate and unambiguous range  measurements can be nnde by transmitting three or more frequencies instead of just two. 
 The radiating  elements might also be mounted on the surface of a sphere, or indeed on an object or any . 280 INTRODUCTION TO RADAR SYSTEMS  shape, provided the_phase at each element .is that .. needed to give a plane wave when the  radiation from all the. 
 The amount of storage required can be reduced signif- icantly by using a feedback integrator shown in Fig. 8.3&: Si = KS^1 + xf (8.9) For a feedback value of K, the effective number of pulses integrated M is M = 1/ (1 - K)9 and for optimal (maximum PD) performance M = 0.63 N9 where N is the number of pulses between the 3-dB antenna beamwidth.11 The detection per- formance is given by the detection curves for M pulses with ABSF = 1.6 dB. Al- though the feedback integrator applies an exponential weighting into the past, its detection performance is only 1 dB less than that of the optimal integrator.8 Un- fortunately, difficulties are encountered when using the feedback integrator to es- timate the azimuth position.11 The threshold-crossing procedure yields estimates only 20 percent greater than the lower bound, but the bias is a function of SIN and must be estimated. 
 Regardless of the model used to describe a ground surface, signals are, in fact,  returned from different positions not on a plane. As a radar moves past a patch of ground  ch16.indd   12 12/19/07   4:54:50 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 There are very differing implementations for the individual function blocks.  Examples will be shown in the proceeding sections.  . 
 The angular fluctuations produced by small targets at long  range may be of little consequence in most instances. However, at short range or with rela-  tively large targets (as might be seen by a radar seeker on a homing missile), angular Hilctua-  tions may be the chief factor limiting tracking accuracy. Angle fluctuations affect all tracking  radars whether conical-scan, sequential-lobing, or monopulse. 
 When the doppler-shifted echo signal is known to lie somewhere within a relatively wide  band of frequencies, a bank of narrowband filters (Fig. 3.6) spaced throughout the frequency  range permits a measurement of frequency and improves the signal-to-noise ratio. The  76INTRODUCTION TORADAR SYSTEMS .<:::n ~ D Co D '0 N I "­ >-e' QJ CW'-- ---'--- _ fa Frequency (a):: D ~ D Co D '0 N I "­ >-e' QJ C W'--- ---""-'LLL.L..-LLLLJ""- __ fa Frequency (b) Figure3.5Frequency spectrum ofCWoscillation of(u)infiniteduration and(b)finiteduration. 
 R. C. Johnson and H. 
 Keeler and Frush157 discuss design consid - erations for a more capable rapid-scanning doppler radar. Any rapid-scanning approach generally must encompass two features: (1) the trans - mit waveform must have a relatively large bandwidth to increase the number of inde - pendent samples available in the desired spatial resolution cell; and (2) the antenna must  be rapidly scanned throughout the desired atmospheric volume either mechanically or  electronically. Mechanically scanned single frequency (standard) weather radars use a  long dwell time to acquire an adequate number of independent samples to accurately  estimate the spectral moment data used for meteorological measurements. 
 It is for this reason that some means of automatic  monitoring of receiver noise-figure is necessary if the radar is to be maintained in prime  operating conditions.  A degradation in the noise figure of a predetermined amount usually is cogsidered as the  criterion for diode failure when defining burnout. Sometimes an increase in noise figure of  3 dB has been used as the criterion.lg In other cases, a I-dB increase has been used.''  However, with Schottky and point-contact diodes, there is an increase in Ilf noise and a  decrease in the breakdown voltage at lower power levels than would be indicated by the above  criteria.14  One of the causes of diode burnout in radar receivers has been the increased RF leakage  through a conventional duplexer due to aging of the TR tube. 
 On some PPI’s, range can only be estimated by reference to the ﬁxed range rings. When the pip lies between the range rings, the estimate isusually in error by 2 to 3 percent of the maximum range of the range scalesetting plus any error in the calibration of the range rings. Radar indicators usually have a variable range marker (VRM) or. 
 This doppler compensation is in the form of inverting data bits, i.e., changing Is to Os and Os to Is, at time intervals cor- responding to 180° phase shifts of the doppler frequency. As an example, the first doppler channel corresponds to a doppler frequency which results in a 360° phase shift over the pulse width. The bits are inverted after every half pulse width and remain inverted for a half pulse width. 
 Davis, M. E., J. K. 
 Using Coherent  and Noncoherent Radars, Proc. IEEE, vol. 62, pp. 
 CLE  OR SITE GROUND 
 The uppermost feedhorn is located at the focal point  of the paraboloid. The azimuth beamwidth is 1.6" and the vertical beamwidth is 4" with  cosecant-squared shaping from 6" to 30". Being a transportable equipment, the antenna is  self-erecting and is stowed inside the shelter through a roof hatch. 
 The height H must produce a vertical beamwidth which illuminates only the swath S.., that is  to be covered. With such constraints, Eq. (14.15) becomes  S/N = 2Pav p;(J0 bcr b;  nf kTo Fn RS.., sin t/J (14.16)  where!= radar frequency. 
 Although the fluctuations in r and f alter the actual tracking from the theoretical, the  equation gives a good indication of the errors to be expected when tracking a point  source such as a beacon. However, skin tracking of an aircraft at low elevation may  result in a departure from the classic periodic error versus elevation, as illustrated in  Figure 9.27, because of an interaction between target angle scintillation and multipath  error that can change the characteristics of the multipath error . When tracking a point source target at close range, the radar main beam is  above the image, but the image is seen by the difference-pattern sidelobes. 
 An Azimuth-Variant Autofocus Scheme of Bistatic Forward-Looking Synthetic Aperture Radar. IEEE Geosci. Remote Sens. 
 The first order con - siderations on hardware that are characteristic of (and essentially unique to) the space  environment include radiation and energetic particles, vibration (especially during  the launch phase), harsh and contrasting thermal environments, often challenging  mass limitations, and a premium on payload power. In Earth orbit and, perhaps sur - prisingly, also at the Moon, a space-based radar must comply with internationally  agreed spectral allocations. These limit both the available bands and the bandwidths,  which impact system design and may constrain certain performance objectives, such  as resolution. 
 H.: Experimental Study of a Diffraction Reflector, IRE Trtrt~s., vol. AP-8.  pp. 
 49.Peebles, P.Z.,Jr.:Multipath AngleErrorReduction UsingMultipk-Target Methods, IEEETrailS, vol.AES-7,pp.1123-1130, November, 1971. .• 50.Howard, J.E.:ALowAngleTracking SystemforFireControl Radars,IEEE1975Illlenl£ltiullal RadarCOI,{erence, pp.412-417. 51.Dax,P.R.:Accurate Tracking ofLowElevation TargetsOvertheSeawithaMonopulse Radar, IEEEColif.PubI.no.105,"Radar-Present andFuture," Oct.23-25,1973,pp.160-165. 
 Unfortunately, the reporting of radar sea echo measurements is seldom  accompanied by a complete description of the sea and wind conditions.  Variation with grazing angle. There are usually identified three scattering regions according  to the grazing angle. 
 SCAN FALSE 
 This form of anomalous propagation over the sea tends to be  more prominent on the leeward side of land masses. Ducting occurs during either the day or  night and can last for long periods of time. It is most likely to occur, however, in the late  afternoon and evening when the warm afternoon air drifts out over the sea. 
 ORDER MODES FOR  ERROR SENSING AND  % 
 A knowledge of tlie transmitted signal is necessary at the receiver site if the maximum  information is to be extracted from the scattered signal. The transmitted frequency is needed to  determine tlie doppler frequency shift. A time or phase reference is also required if the total  scattered patti lengtli (D, + D,) is to be measured. 
   NO   PP n  .OVEMBER    $ 0 3CHOLNIK AND  * / #OLEMAN  h)NTEGRATED ) 
 Figure 1.15 - Principles of a parabolic reﬂector. Figure 1.16 - Slotted waveguide antenna. 21Indicator The primary function of the indicator is to provide a visual display of the ranges and bearings of radar targets from which echoes are received. 
 10. G. V . 
 1 EEE. vol. 56, p. 
 14, no. 3, pp. 101–111, June 2002. 
 6.13 WAVEFORM GENERATION   AND UPCONVERSION The exciter function of waveform generation and upconversion is often tightly coupled  with the receiver function. The requirement for coherence between the receiver and  exciter is a major factor for this tight coupling and the use of the same LO frequen - cies within the receiver and exciter usually results in hardware savings. Similar to  the migration to digital receiver architectures, the exciter functionality is increasingly  being implemented using digital approaches.FIGURE 6.23  Diplex operation improves the sensitivity of the receiver ch06.indd   47 12/17/07   2:04:27 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The primary surveillance radar operates . FIG. 5.16 NAVSPASUR transmitter design tradeoffs. 
 DOMAIN WAVEFORM 4HE BASIC &-#7 RADAR SYSTEM IS PARTICULARLY SENSITIVE TO CERTAIN PARAMETERS )N PARTICULAR  IT REQUIRES A HIGH DEGREE OF LINEARITY OF FREQUENCY SWEEP WITH TIME TO AVOID SPECTRAL WIDENING OF THE )& AND HENCE DEGRADATION OF SYSTEM RESOLUTION $ENNIS AND 'IBBS  MADE AN ASSESSMENT OF THE  SENSITIVITY OF TIME SIDELOBE LEVEL TO LINEARITY AND SHOWED THE RATIO OF SIDELOBE TO PEAK LEVEL WAS DEPENDENT ON THE SWEEP LINEARITY 0RACTICALLY  THE EFFECT OF A NONLINEARITY OF A FEW PERCENT IS TO CAUSE SIGNIFICANT TIME SIDELOBES  AS THIS NEEDS TO BE COMPENSATED IN THE TRANSMITTER MODULATOR DESIGN 4HE 3&#7 RADAR TRANSMITS A SERIES OF INCREMENTAL FREQUENCIES AND STORES THE  RECEIVED )& SIGNAL TO THEN CARRY OUT A &OURIER TRANSFORM RECONSTRUCTION OF THE TIME 
 9.13). Allthese methods and others areinwide use. Ofthe complex motions, the spiral scan has been mentioned as derived from conical scan, and more particularly from three varieties just listed. 
 Scharrr11an, H.: Three New Ferrite Phase Shirters, Proc. IRE, vol. 44, pp. 
 The clock generator  provides clocks to the A/D converters and the direct digital synthesizer and provides  the basis for the signals that define the radar transmit and receive intervals. The direct digital synthesizer in Figure 6.1 is used to generate the transmit wave - forms at an IF frequency prior to upconversion to the RF output frequency. Filtering  in the exciter is required to reject aliased signals from the direct digital synthesizer and  unwanted mixer products. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 14.44  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 12. 
 BASED PLATFORM )TS PRECESSING  
 The most extensive analysis ofthis sort has been carried out byJ.W.and D.Ryde, upon \vhose~\,ork' thecurves ofFig. 2.17 arebased. The direct measurements ofattenuation and rainfall which ha~’e been made confirm these predictions satisfactorily. 
 '(Z  CROPLAND DATA FOR TWO YEARS OBTAINED WITH A MICROWAVE  ACTIVE SPECTROMETER AFTER 2 + -OORE  + ! 3OOFI  AND   3 - 0URDUSKI  Ú )%%%   .   '2/5.$ %#(/  £È°Î£ 4HE BASIS FOR THE LINEAR MODEL IS A COMBINATION OF THE 3KYLAB RESULTS OVER .ORTH  !MERICA AND THOSE FROM +ANSAS CROPLAND MEASUREMENTS OVER THREE COMPLETE SEASONS  WITH THE MICROWAVE ACTIVE SPECTROMETER -!3  4HE  
 Richter, J.H.,andH.V.Hitney:TheEffectoftheEvaporation DuctonMicrowave Propagation, Nal'alElectronics Lahoratory Center,SanDiego,California, Technical Report1949,Apr.,171975. Hitney.H.V..andJ.H.Richter: Integrated Refractive EffectsPrediction System(IREPS), Naval Engi/H'l'rs JO!lntal, vol.2,pp.257262,April,1976. Hitney,H.V.,andJ.H.Richter: Integrated Refractive EffectsPrediction System(IREPS), URSI Commission FOpenSymposium, Propagation inNon-Ionized Media,LaBaule,France,Apr.28to May6,1977. 
 STAGE #)# FILTER RESPONSE  AND THE MAIN PASSBAND HAS MORE ATTENUATION TOWARD THE EDGES )N TYPICAL APPLICATIONS  A #)# DECIMATOR IS FOLLOWED BY A &)2 LOWPASS FILTER AND A FINAL DECIMATION BY  4HAT IS  A DECIMATE 
 MTI RADAR  2.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 The clutter attenuation against point clutter based on this definition will be the same  before or after pulse compression and will also be identical to the value of CA obtained  against distributed clutter with identical spectral characteristics. For the practical measurement of CA against a single piece of point clutter (i.e.,  corner reflector), the total energy must be integrated, per the above definition, at the  input and output of each doppler filter. The calculation of the energy is best performed  prior to pulse compression since the precise duration of the uncompressed pulse, and  therefore the integration window, is accurately known. 
 24. We must there- fore expect aminimum intheratioofnoise output topeak signal output, atsome value of@closely related tol/T. Itisnot obvious that such a minimum should represent precisely thebest condition forthe detection ofthesignal. 
 1, pt. 2, pp. 56-58, 1953. 
 Allan, A. Brand, and R. Ste-Mari, “Description  of RADARSAT-2 synthetic aperture radar design,” Canadian J. 
 BINATORIAL TERM  G      $.- .. -$$ - 
 SWATH INCIDENT ANGLES IS  n nn  .OTE THAT THE *APANESE  USUALLY CITE THESE ANGLES AS hOFF 
 LOOKING IN 3!2 JARGON !DDITIONAL LOOKS REQUIRE PROPORTIONALLY MORE BANDWIDTH )T FOLLOWS THAT LARGE TWO 
 TIONS OF ALL ASPECTS OF CLUTTER BEHAVIOR UNDER ALL POSSIBLE ENV IRONMENTAL CONDITIONS )N  SPITE OF OVER  YEARS OF EFFORT  THE THEORY OF SEA CLUTTER DOES NEITHER OF THESE TASKS VERY WELL  AS WE WILL SEE IN THIS SECTION )N THE DEVELOPMENT OF MODELS OF SEA SCATTER BASED ON PHYSICAL THEORY  THERE ARE  ESSENTIALLY TWO BASIC AND DISTINCT APPROACHES (ISTORICALLY  THE FIRST APPROACH ASSUMED SEA SCATTER TO HAVE ITS ORIGIN IN SCATTERING  FEATURES  OR OBSTACLES  ACTUALLY PRESENT ON OR  NEAR THE SEA SURFACE %ARLY SCATTERING MODELS INCLUDED RAIN TO MODEL SPRAY    SMOOTH  CIRCULAR METALLIC DISKS   ARRAYS OF SEMI 
 The over-all receiver bandwidth (i.e., the. SEC. 12.4] I-FAMPLIFIER DESIGN 445 mediate frequency considerably greater than this isrequired inorder that i-fsine waves can befiltered out ofthevideo amplifier. 
 VERSIONS WITHIN THE RECEIVER USING ,/ FREQUENCIES GREATER THAN THE 2& FREQUENCY WILL CAUSE A DOPPLER FREQUENCY INVERSION  SO EACH CONVERSION MUST BE CONSIDERED IN ORDER TO ACHIEVE THE CORRECT SENSE OF  ) AND 1 AT THE RECEIVER OUTPUT &ORTUNATELY  AN INCORRECT  ) AND 1 RELATIONSHIP CAN EASILY BE FIXED EITHER IN THE RECEIVER OR THE SIGNAL PROCESSOR   BY SWITCHING THE ) AND 1 DIGITAL DATA OR BY CHANGING THE SIGN OF EITHER ) OR 1 'AIN OR 0HASE )MBALANCE  )F THE GAINS OF THE  ) AND 1 CHANNELS ARE NOT EXACTLY  EQUAL OR IF THEIR #/(/ PHASE REFERENCES ARE NOT EXACTLY  DEGREES APART  AN INPUT SIGNAL AT FREQUENCY  V WILL CREATE AN OUTPUT AT BOTH THE DESIRED FREQUENCY  V 
 At that time the term ‘radar ’had not been adopted and these systems were known as Air-to-Surface Vessel (ASV). The ﬁrst system, building on experiment work undertaken in the late 1930s, was ASV Mk. I, which entered service in early 1940. 
 1 2 3 4 5 6 7 8 9 0 DOC DOC 0 1 9 8 ISBN 978-0-07-148547-0 MHID 0-07-148547-3 Sponsoring Editor  Wendy Rinaldi Editorial Supervisor  Janet Walden Project Editor  LeeAnn Pickrell Acquisitions Coordinator  Mandy Canales Copy Editor  LeeAnn Pickrell Proofreader  Susie Elkind Production Supervisor  Jean Bodeaux Composition  International Typesetting & Composition Illustration  International Typesetting & Composition Art Director, Cover  Jeff Weeks Cover Designer  Mary McKeon Information has been obtained by McGraw-Hill from sources believed to be reliable. However, b ecause of the possib ility of human or mechanical error by our sources, McGraw-Hill, or others, McGraw-Hill does not guarantee the accuracy, adequacy, or completeness of any information and is not responsible for any errors or omissions or the results obtained from the use of such information..     v CONTENTS Contributors xiii Preface xv Chapter 1 An Introduction and Overview of Radar Merrill Skolnik1.1 1.1  Radar in Brief / 1.1 1.2  Types of Radars / 1.5 1.3  Information Available from a Radar / 1.7 1.4  The Radar Equation / 1.10 1.5  Radar Frequency Letter-band Nomenclature / 1.13 1.6  Effect of Operating Frequency on Radar / 1.14 1.7  Radar Nomenclature / 1.18 1.8  Some Past Advances in Radar / 1.19 1.9  Applications of Radar / 1.20 1.10  Conceptual Radar System Design / 1.22 Chapter 2 MTI Radar William W. 
 Hard or soft limiters can also be used to counter jamming signals. They are nonlinear  memoryless devices that cut jamming signals having wide amplitudes. The Dicke-Fix  receiver counters high rates of swept-frequency CW jamming and swept spot noise jam - mers.29,139 In a radar receiver, the Dicke-Fix uses a wideband intermediate-frequency  (IF) amplifier and a limiter ahead of the narrow-bandwidth IF amplifier. 
 RETICAL 03& BUT IS SOMEWHAT DIFFERENT FROM IT  ESPECIALLY IN THE SIDELOBES  DUE TO PHASE  NOISE  MOTION COMPENSATION IMPERFECTIONS  AND OTHER hREAL 
 These results are consistent with predicted scattering coefficient variations based on  the topography and the electrical properties of the surfaces. Subsequently, observa - tions over the Indian Ocean with the Jindalee radar, employing carefully calibrated  transponders, revealed ~25 dB variations in the ocean scattering coefficient, depend - ing on sea state.76 Land Clutter.  Mapping of skywave backscatter from terrestrial (land) surfaces  is of interest for two main reasons. 
 A block diagram of a monopulse radar with provision for extracting error signals in both  elevation and azimuth is shown in Fig. 5.9. The cluster of four feeds generates four partially  overlapping antenna beams. 
 Real parts of ﬁrst right and ﬁrst left singular vectors for the SAR raw data matrix decomposition. The range amplitude results almost constant, as the transmitted chirp is assumed to be. The azimuth singular vector is shaped by the azimuth antenna beam pattern. 
 492 13.7 The Generation ofRectangular Waveforms. 496 13.8 The Generation ofSharp Pulses. 501 13.9 Electronic Switches ... 
 24.16 SNR is given as a function of frequency and range in the form of an oblique sound- ing, as in Fig. 24.15, but for 0800 GMT (night). selected antenna gain patterns, transmitted powers, target RCS, and coherent in- tegration times (CIT). 
   -4) 2!$!2  Ó°Î )N THEORY  IT IS POSSIBLE TO SYNTHESIZE ALMOST ANY VELOCITY RESPONSE CURVE WITH DIGI 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar.  CIVIL MARINE RADAR  22.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 If slots were spaced at the guide wavelength in an attempt to get an equi-phase  wavefront at the antenna face, then large grating lobes would be generated in the far- field pattern. 
 95 97  'Two-frequency MTI. 147 148  Twystron. 208  Type I1 servo system, 178. 
 Stability Requirements. Frequency oftheBeating Oscillators.— The amplitude ofthevideo signal from astationary target canbewritten. SEC.165] STABILITY REQUIREMENTS 639 as y=y~Cosl+, (1) where VOisthe i-famplitude and 1#1isthe phase difference between the i-fecho signal and the reference signal. 
 High-range-resolution with monopuhe. The inclusion of a monopulse angle-measurement to a  high-range-resolution radar was mentioned briefly in Sec. 5.8. 
 S. Johnson: Adaptive Detection Mode with Threshold Control as a Function of  Spatially Sampled Clutter-Level Estimates, RC A Rev., vol. 29, pp. 
                     
 ELS FOR AVERAGE BACKSCATTER FROM LARGE AREAS )N PARTICULAR  THESE INCLUDED MEA 
 An alternative AGC filter design would maintain the AGC loop gain up to frequencies  much higher than the conical-scan frequency. The scan modulation would be effectively sup­ pressed in the output of the receiver, and the output would be used to measure range in the  normal manner. In this case, the error signal can be recovered from the AGC voltage since it  varies at the conical-scan frequency. 
 FRIENDLY INTERFACES RUN  ON LOW 
 GENERATED COMPONENT  OF THE RMS SLOPE OF hOILEDv W ATERS IS SIGNIFICANTLY .   3%! #,544%2  £x°ÓÇ SMALLER THAN THAT OF hCLEANv WATER 4HE HEAVY COMMERCIAL OILS USED IN THEIR EXPERIMENT  WERE EFFECTIVE IN SUPPRESSING SMALL 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section.  RADAR CROSS SECTION  14.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 Differential Equations. 
 1348–1351. 9. Rödelsperger, S.; Coccia, A.; Vicente, D.; Meta, A. 
 “Dark Trace” S’creen.s.--Certain normally white salts, notably the alkali halides such asKC1, have theproperty ofdarkening foratime ata point where they have been struck byanelectron beam ofsufficient energy. 1This phenomenon hasbeen made useofinoneform ofcathode- raytube, known asthe “skiatron” (screen type isP-10) used forpro- jection purposes. Bymeans ofanintense external light source, opaque projection ofthe tube face magnified several diameters ispossible. 
  D  
 D. Wilson: Track Initiation in a Dense Detection Environment, Naval Researclr  Lahoratory (Washington, D.C.) Rept 8238, July 28. 1978. 
          &)'52%  !NTENNA POINTING ANGLES WHERE CLUTTER DOPPLER  MAP TO A SINGLE DOPPLER FILTERS PASSBAND. 
 "EAM-APn n n n n n n n $OPPLER"EAM3HARPn n n n n n n nK 3!2 n n n n n nK n nK ! 
 IN  TIME SIDELOBE LEVELS ON ONE SIDE OR THE OTHER BEGIN TO INCREASE .OTE THAT AN  F" RATIO  OF  CORRESPONDS TO A DOPPLER SHIFT ASSOCIATED WITH APPROXIMATELY A -ACH  TARGET  AT A 3 BAND CARRIER FREQUENCY )N GENERAL FOR  0N  K  WAVEFORMS  THE INTEGRAL OF THE WEIGHTING FUNCTION PROVIDES  THE RELATIONSHIP BETWEEN TIME AND FREQUENCY MODULATION AS SHOWN IN %Q    T 4KKX D XNF " 
 197-201. December, 1957.  47. 
   DESIGNED AROUND AN ARRAY OF  HORIZONTAL SLOTTED WAVEGUIDES  EACH OF WHICH WAS CENTER 
 Strings are of interest at RCS test facilities because they  sometimes are used as “invisible” target supports. FIGURE 14.3  RCS of a lossy dielectric sphere with n = 2.5 + i0.01 ( after J. Rheinstein5  © IEEE 1968 ) ch14.indd   6 12/17/07   2:46:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 TO 
 G. Long, “Spaceborne radar measurement of wind velocity  over the ocean––An overview of the NSCAT scatterometer system,” Proceedings of the IEEE ,  vol. 79, pp. 
 design in the orthogonal plane. The parabolic cylinder antenna fed from a line source is  convenient for obtaining independent control of the patterns in the two orthogonal planes.  This type of antenna, however, is generally bulkier and heavier than a reflector fed from a  si~iglc poirit source. 
 Doppler-based  techniques are applicable to the along-track direction.142 However, the orbit’s alti - tude-velocity parameter (Table 18.1) may be so large that the available ambiguity-free  range-doppler window is too small to be useful. Narrowing the effective antenna pat - tern in the cross-track direction presents even more of a challenge. The second problem is range sidelobes. 
 The Burgers-Rott vortex model is actually an exact solution obtained from the Navier-Stokes equation with the assumption that the vortex is stationary and axisymmetric, and the radial velocity Vrand the circumferential velocity Vθare independent of the axial coordinate z[19–22], i.e., Vr=Vr(r),Vθ=Vθ(r),Vz=Vz(r,z) (1) The continuity equation of the incompressible ﬂow is ∂(rV r) ∂r+∂(rV z) ∂z=0 (2) The projection of the N-S equation in the circumferential direction can be expressed as Vr∂Vθ ∂r+VrVθ r=υ(∂2Vθ ∂r2+1 r∂Vθ ∂r−Vθ r2) (3) where υis the kinematic viscosity coefﬁcient of the molecule. Providing the circulation of velocity Γ=2πrVθ, Equation (3) can be rewritten as d2Γ dr2=(1 r+Vr υ)dΓ dr(4) Since the radial velocity Vris only a function of the radial coordinate r, the general solution of Equation (4) can be expressed as Γ=c1H(r)+ c2 (5) 313. Sensors 2019 ,19, 1529 where c1and c1are constants, and H(r)=r/integraldisplay 0xexp⎧ ⎨ ⎩x/integraldisplay 0[Vr(s)/υ]ds⎫ ⎬ ⎭dx (6) Considering r→0at the vortex core, Γ→0should be ensured. 
 The  normal antenna pattern is depicted in Fig. 7.26a as a square beam extending from (J = 0 to  0 = 00. The cosecant-squared pattern in Fig. 
 VIEW ARRAYS -ANUFACTURABILITY #ONSIDERATIONS  "Y DEFINITION  THE USE OF --)# COMPONENTS  INVOKES A MICROELECTRONIC ASSEMBLY  TEST  AND HANDLING MANUFACTURING INFRASTRUCTURE 4HE MANUFACTURING OF LOW 
 The Nyquist rate is a minimum  sampling frequency for a signal, a bound, and  meeting the bound is necessary, but not sufficient, to ensure that no aliasing occurs.  Consider the case presented in Figure 25.7 a, which is the same bandlimited bandpass  signal shown in Figure 25.5, but shifted in frequency so that it doesn’t begin exactly  at B. The sampled signal spectrum in Figure 25.7 b shows that, although the sampling  rate satisfies the Nyquist bound, the sampled signal is still aliased. 
 Katsaros, and D. Vandemark, “A unified directional spectrum for  long and short wind-driven waves,” J. Geophys. 
 CASE BASIS "ISTATIC 3CATTERING #OEFFICIENT  6ALUES OF THE SCATTERING COEFFICIENT  S" VARY AS A  FUNCTION OF THE SURFACE COMPOSITION  FREQUENCY  AND GEOMETRY AND ARE OBTAINED THROUGH FIELD MEASUREMENT PROGRAMS )N   - - 7EINER  DOCUMENTED AND EVALUATED ALL  UNCLASSIFIED MEASUREMENTS OF  S" HOWEVER  ITS USE WAS RESTRICTED TO 53 GOVERNMENT  AGENCIES )N   7ILLIS USED 7EINERS REFERENCES TO RECONSTRUCT AND EVALUATE TYPICAL DATA FROM 7EINERS WORK   WHICH BECAME AVAILABLE FOR PUBLIC USE IN 7ILLIS  )N    7EINERS WORK WAS CLEARED FOR PUBLIC RELEASE  MAKING AVAILABLE IN ONE DOCUMENT ALL  UNCLASSIFIED  S" DATA AND ANALYSIS THROUGH  7EINER THEN UPDATED HIS WORK WITH DATA  AVAILABLE THROUGH  AND REPUBLISHED IT IN #HAPTER  OF !DVANCES IN "ISTATIC 2ADAR  4HIS SECTION SUMMARIZES AND COMMENTS ON ESSENTIAL ELEMENTS OF 7EINERS WORK &)'52%  3IMULATED BISTATIC 2#3  REPLOTTED AS A FUNCTION OF BISTATIC ANGLE FOR A CONDUCTING CYLINDER    BY  CM AT  '(Z  (( POLARIZATION  AFTER 2 # 0ADDISON ET AL  A  NEAR END ON   B   ASPECT  ANGLE  AND C  BROADSIDE.   ")34!4)# 2!$!2   ÓÎ°ÓÎ 4HE AVAILABLE DATABASE FOR TERRAIN  AND SEA CLUTTER AT MICROWAVE FREQUEN 
 The enormous wartime investment ofmoney, skill, and productive facilities inradar paid theAllies handsome dividends with thefleet, inthe air, and onthebattlefield. 1The uses ofradar inapeaceful world were jusb beginning tobeworked out in1946. Some ofthese aredealt with inVol. 
 Other pulse-compression waveforms. Other pulse-compression methods include nonlinear  FM, discrete frequency-shift, polyphase codes, compound Barker codes, code sequencing,  complementary codes, pulse burst, and stretch. Each will be discussed briefly. 
 Simple pulsed systems used analog  RF switches to gate the LO on and off. Frequency modulated signals were generated  by surface acoustic wave (SAW) devices. Simple binary phase modulation schemes  like pseudo-random noise waveforms were also possible. 
 The rendezvous radar set (RRS) will be an X-band coherent, range-gated, pulse doppler radar with redundant . PERFORMANCE (Ib) (THOUSANDS) (a) PERFORMANCE(Ib)(THOUSANDS) (b) FIG. 22.16 Cost per pound to low earth orbit, (a) Eastern Test Range launch due east, (b) Western Test Range launch into polar orbit.SCOUT (15789) CONESTOGA MA (10714) ATLAS H (7955) CONESTOGA IV A (5484) MEDIUM LAUNCH VEHICLE (5161) ATLAS G/CENTAUR (4444) ATLAS K/CENTAUR (4483) DELTA 392OA(4070) TITAN 34D (2232)TITAN IV (2545)STS (1636) SCOUT (19565) CONESTOGA MA (12500) AT LAS H (14000) TITAN Il (8333) CONESTOGA IVA (7083) ATLAS E (8235)STS(2813) TITAN 34D (2727)TITAN IV (3226)COST PER POUND ($/lb) (THOUSANDS) COSTPER POUND ($/lb) (THOUSANDS) . 
 If reciprocal phase shifters are used, the energy reflected from the radiating aperture will pick up equal additional phase shift on reflection from the radiating aperture, resulting in a beam at the input aperture that is phased to scan to twice the original scan angle (in sin 6 space). Some energy will undergo secondary re- FIG. 7.16 Nonisolating feed showing spurious lobes when reciprocal phase shifters are used.INPUT APERTURERADIATING APERTURE COLLIMATINGLENS PHASE SHIFTERS2 sin 93 sin 6 sin 9 . 
 TheIFamplifier shouldbe designed asamatc/tedfilter;i.e.,itsfrequency-response functionH(f)shouldmaximize the peak-signal-to-mean-noise-power ratioattheoutput.Thisoccurswhenthemagnitude ofthe frequency-response function [H(f)Iisequaltothemagnitude oftheechosignalspectrum IS(f)I.andthephasespectrum ofthematched filteristhenegative ofthephasespectrum of theechosignal(Sec.10.2).Inaradarwhosesignalwaveform approximates arectangular pulse.theconventional IFfilterbandpass characteristic approximates amatched filterwhen theproductoftheIFbandwidth Bandthepulsewidthtisoftheorderofunity,thatis,Bt~1. Aftermaximizing thesignal-to-noise ratiointheIFamplifier, thepulsemodulation is extracted bytheseconddetector andamplified bythevideoamplifier toalevelwhereitcanbe Dupleller Antenna Low-noise RF amplifierIFamplifier (matched filter) Figure1.2Blockdiagram ofapulseradar.. Figure 1.3 (a) PPI presentation displaying range vs. 
 ING THE PRODUCT   0!R OF AVERAGE TRANSMITTER POWER BY THE EFFECTIVE ANTENNA APERTURE  ! MILITARY RADAR SHOULD ALWAYS HAVE  D" MORE POWER 
 S. Gunn and J. S. 
 Meteorol., vol. 16, pp. 6-l l, February, 1959. 
 M RESOLUTION   
 96 HOW RADAR WORKS  opposite direction until the original stable state is  reached.  Quite a number of radar circuits are coupled through  . a device known as a ‘cathode-  follower.’- To see why this is  necessary consider Fig. 
 Chu, and L. Peters, Jr., “First-order equivalent current and  corner diffraction scattering from flat plate structures,” IEEE Trans ., vol. AP-31, pp. 
 Since, inround numbers, there are10’wavelengths contained intwice the maximum range, itisapparent that theoperation will not even approxi- mate the above description unless the short-time frequency stability. 154 C-W RADAR SYSTEMS [SEC. 5.11 exceeds one partin 10’. 
 Another sourceofnoisepredominant atthelowerradarfrequencies isurbannoise,also knownasman-made noise.Noisefromautomobile ignition, electricrazors,powertools,and fluorescent lightsareexamples. Itisoflittleconcern atUHForhigherfrequencies.55 Solarnoise.Thesunisastrongemitterofelectromagnetic radiation, theintensity ofwhich varieswithtime.Theminimum levelofsolarnoiseisduetoblackbody radiation atatempera­ tureofabout6000K.56.57Thesolarnoiseisunlikemostothernoisemechanisms inthatits powerincreases withincreasing frequency. Solarstorms(sunspots andflares)canincrease the solar-noise levelseveralordersofmagnitude overthatofthe"quiet,"orundisturbed sun. 
 LUTION /BVIOUSLY  EACH MODE MUST NOT COMPROMISE SOME REQUIRED LEVEL OF MISSION STEALTH n ! MODERN FIGHTER IS NET 
 Therefore, the conventional unit of Z is  in mm6/m3. For ice particles, Di is sometimes expressed as the diameter of the water  droplet that would result if the ice particle were to melt completely. However, the radar  scattering process for the many shapes and temperatures of ice particles is extremely  complicated and a definitive generalized expression cannot be given. 
 (2) 251. Sensors 2019 ,19, 346 Haranges from 0 to 1. As shown in equation (2), Hais normalized by the sum of P(k)and is not concerned with RCS amplitude. 
 MESH  OR METALIZED FABRIC SURFACE IN ORDER TO MINIMIZE WIND RESISTANCE  REDUCE WEIGHT  ANDOR ENABLE STOWAGEDEPLOYMENT 3OME COMMON REFLECTOR MESH SURFACE PATTERNS ARE            
 Abramovich, S. J. Anderson, and N. 
 8.: The Design or Airborne Doppler Velocity Measuring Systems, IRE Trans., vol. ANE-4.  pp. 
 (Courtesy S. Applebaum and P. W. 
 3  CONTINUOUS WAVE AND PULSED RADAR  ................................ .. 4  PULSED RADAR  ................................ 
 Farina, P. Lombardo, and L. Ortenzi, “A unified approach to adaptive radar processing  with general antenna array configuration,” Special Issue on “New trends and findings in  antenna array processing for radar,” Signal Processing , Elsevier, vol. 
 /\ small aircraft or missile decoy can be designed to have a radar cross section comparable  with that of a large aircraft by fitting it with radar signal enhancement devices such as corner  rcOcctors, Luneburg renectors, or active repeaters. The decoy could also be outfitted with a  small jammer to mimic jammers on the target aircraft in order to make the two appear  identical.  Decoys might be carried on board attacking bomber aircraft and launched outside the  normal radar detection ranges. 
 J. H.. and I). 
 41-51. Jan .• 1971.  126. 
 On both radars the anti-sea clutter control has been carefully adjusted to remove sea clutter. The close range targets are clearly visible on the 10 cm. right, whereas they are missing on the 3 cm. 
 BEAM SYSTEMS ALLOW ONE TO DETERMINE THE QUALITY  OF THE MEASURE 
 Hannan and P. A. Loth, “A monopulse antenna having independent optimization of the sum  and difference modes,” IRE Int. 
 (Courtesy of I. D. OUn and F. 
 54. Carpentier, M. H.: " Radars: New Concepts," Gordon and Rrcucli, New York, 1968, scc. 
 The numbers shown do not include heater power, solenoid power, or cooling-system power, which may be significant. Ion Pump. Residual outgassing in a microwave tube can spoil its vacuum and cause RF or dc breakdown. 
 F., F. T. Ulaby. 
 , AMS, Norman, 1993, pp. 393–395. 160. 
 Figure 10.38a shows typical pulse- forming networks, the ratings for which are given inTable 10.6. Figure 10.38b shows anetwork used inanexperimental 20-Mw pulser, the largest designed at Radiation Laboratory. Two of the smallest networks used are shown forsize comparison: theone onthe left has arating of5kw pulse power output; the other one iselectrically equivalent tothe net- work (1)ofFig. 
 40. Bearse, S. V.: Knitted Antenna Solving Knotty Problems, Microwaves, p. 
 ,. Figure14.10Photograph oftheARSR-3, airroutesurveillance radar.(Col/rtt'sy ofWeslillyhollst', IlIc.) Table14.1Characteristics oftwoairtrafficcontrolradars28.46.56 Frequency band Frequency Instrumented range Peakpower Averagepower Noisefigure Pulsewidth Pulserepetition frequency Antenna rotation rate Antenna size Azimuth beamwidth Elevation coverage Antenna gain Polarization Blindspeed MTIimprovement factorARSR-3 L 1250-1350 MHz 200nmi(370km) 5MW 3.6kW 4dB 2/IS 310-365Hz 5rpm 12.8mby6.9m 1.250 400 34dB hor,vert,orcircular 1200knots 39dBASR-8 S 2700-2900 MHz 6Onmi(lllkm) 1.4MW 875W 4dB 0.6jlS 700-1200 Hz 1040Hz(ave) 12.8rpm 4.9mby2.7m 1.35° 30° 33dB vertorcircular 800knots 34dB. OTIiER RADAR TOPICS 539  vehicle on wliicli tile radar is carried; rcliahility (mean tinie betwceti failures), availability  (fraction of time tlie radar works properly). 
 SHIP TO THE %ARTHS SURFACE 4HE TRAPPING LAYER IS INDICATED GRAPHICALLY BY THE SOLID BLACK - 
 A. L. C.: 7'racking arid Associated. 
 DETERMINED MARINE RADAR SPECTRUM LIMITS SEE  FOR EXAMPLE  7ILLIAMS   3INCE THE PEAK TRANSMITTED POWER FROM  SOLID 
 64. P. H. 
 BASED  AIRBORNE  OR SPACE 
 Interferometry . Interferometry by radar (Figure 18.6) implies measurements that  are based on phase differences sensed through two different observations of the same  phenomena.42–45 Phase differences arise from microwave-scale changes that are due  either to differential viewing aspect or to elements of motion in the scene. In general  terms, the sensitivity of phase measurements depends to first order on (1) the radar’s  wavelength, (2) the spatial or temporal baseline of the contributing data sets, and  (3) the scale of spatial or temporal differential signals. 
 for the purpose of obtaining some knowledge of distance and velocity. This was  THENATURE OFRADAR9 radiateorprojectadivergent beamoftheseraysinanydesireddirection, whichrays,ifcoming acrossametallic object,suchasanothersteamerorship,wouldbereflected backtoareceiverscreened fromthelocaltransmitter onthesending ship,andthereby, immediately revealthepresence and bearingoftheothershipinfogorthickweather. Although Marconi predicted andsuccessfully demonstrated radiocommunication be­ tweencontinents, hewasapparently notsuccessful ingainingsupport forsomeofhisother ideasinvolving veryshortwaves.Onewastheradardetection mentioned above;theotherwas thesuggestion thatveryshortwavesarecapableofpropagation wellbeyondtheopticallineof sight-a phenomenon nowknownastropospheric scatter.Healsosuggested thatradiowaves beusedforthetransferofpowerfromonepointtotheotherwithouttheuseofwireorother transmission lines. 
 Thus a  bistatic-radar system might be more expensive than a monostatic radar of comparable detec­ tion ability since the cost of developing the additional site (building roads, sleeping quarters,  mess facilities, etc.) can be a significant fraction of the total.  Although the bistatic radar cannot readily imitate the hemispherical coverage of mono­ static radar, it is possible for the monostat.ic radar to give fence coverage by using fixed, rather  than rotating. antennas. 
 If the target carries a beacon or some  other form of echo-signal augmentor, the doppler frequency shift may be simulated by trans­ lating the echo frequency, as with a single-sideband modulator.  The two frequencies of the two-frequency radar were described as being transmitted  simultaneously.63 They may also be transmitted sequentially in some applications by rapidly  switching a single RF source.  A large difference in frequency between the two transmitted signals improves the accuracy  of the range measurement since large /:if means a proportionately large change in 6.<j) for a  given range. 
 Given a time T0 allocated to the mea- surement and a signal bandwidth Oy(Hz), there will be approximately oy70 inde- pendent samples of the square of the signal envelope. It follows, therefore, that an estimate P1. of the mean power for this process will have a variance or mean square error given by P2 var (Pr] « ^- (23.36) OyJ0 Substituting for oy from the expression oy = 2ov/X, where CTV is the width of the doppler spectrum, Eq. 
 'ATE $URATION 2' /VERLAP TT   TG   TS  TB     )00   TG 4RANSMIT 0ULSE              -& /UTPUT h6OLTAGEv      -& /UTPUT h0OWERv  4IME .ORMALIZED BY 2ANGE 
 GRADIENT HENCE THE LONG BOOM AND COUNTER 
 &UNCTION  %LECTRONICALLY 3CANNED   !DAPTIVE 2ADAR  v  0ROC OF )NT #ONF 2ADAR   %DINBURGH  /CTOBER n    0UBLICATION NO    ,ONDON  5+ )%%  PP n  $ 'IULI  h0OLARIZATION DIVERSITY IN RADARS v 0ROC )%%%  VOL   PP n  &EBRUARY   , -AISEL  h0ERFORMANCE OF SIDELOBE BLANKING SYSTEMS v  )%%% 4RANS  VOL !%3n  NO     PP n  -ARCH   0 / !RANCIBIA  h! SIDELOBE BLANKING SYSTEM DESIGN AND DEMONSTRATION v  -ICROWAVE *  VOL    PP n  -ARCH  REPRINTED IN 2EF     $ ( (ARVEY AND 4 , 7OOD  h$ESIGNS FOR SIDELOBE BLANKING SYSTEMS v  )%%% )NT 2ADAR #ONF  2EC  !PRIL   PP n  - /3ULLIVAN  h! COMPARISON OF SIDELOBE BLANKING SYSTEMS   )%% )NT #ONF 2ADARn   #ONF   0UB   ,ONDON  5+  /CTOBER n    PP n  ! &ARINA AND & 'INI  h#ALCULATION OF BLANKING PROBABILITY FOR THE SIDELOBE BLANKING 3,"  FOR  TWO INTERFERENCE STATISTICAL MODELS v  )%%% 3IGNAL 0ROCESSING ,ETTERS   VOL   NO   PP n   !PRIL   ! &ARINA AND & 'INI  h"LANKING PROBABILITIES FOR 3," SYSTEM IN CORRELATED CLUTTER PLUS THERMAL  NOISE v )%%% 4RANS  VOL 30n  NO   PP n  -AY   ! &ARINA AND & 'INI  h$ESIGN OF 3," SYSTEMS IN PRESENCE OF CORRELATED GROUND CLUTTER v   )%% 0ROC  VOL   PT &  NO   PP n    ! $E -AIO  ! &ARINA  AND & 'INI  h0ERFORMANCE ANALYSIS O F  THE SIDELOBE BLANKING SYSTEM FOR  TWO FLUCTUATING JAMMER MODELS v )%%% 4RANS  VOL !%3n  NO   PP n  *ULY   $ ! 3HNIDMAN AND 3 3 4OUMODGE  h3IDELOBE BLANKING WITH INTEGRATION AND TARGET FLUCTUATION v  )%%% 4RANS  VOL !%3n  NO   PP n  *ULY    0 7 (OWELLS  h)NTERMEDIATE &REQUENCY 3IDELOBE #ANCELER v 53 0ATENT       !UGUST     3 0 !PPLEBAUM  0 7 (OWELLS  AND # +OVARIK  h-ULTIPLE ) NTERMEDIATE &REQUENCY 3IDE 
 MENT IS THAT THE DATA MUST BE MUTUALLY COHERENT 4HAT IS RELATIVELY EASY FOR THE RECEIVER  WHICH ONLY NEEDS TO HAVE TWO CHANNELS THAT CAPTURE SIMULTANEOUSLY THE PHASE AND AMPLITUDE OF TWO ORTHOGONAL POLARIZATIONS OF THE BACKSCATTERED FIELD /N THE OTHER HAND  ONLY ONE POLARIZATION CAN BE TRANSMITTED AT A TIME )LLUMINATING THE SCENE WITH TWO POLARIZATIONS REQUIRES THE TRANSMITTER TO BE TOGGLED BETWEEN ORTHOGONAL POLARIZA 
 TO 
 Hunter and T. B. A. 
 X-rays affect transmitter weight because of the shielding required to protect personnel (and sensitive semiconductors). Efficiency. This strongly affects transmitter weight, cost, and cooling re- quirements as well as prime power. 
 Held, “Imaging radar polarization signatures: Theory and  observation,” Radio Sci. , vol. 22, pp. 
 A phase change of the error signal is equiva-  lent to a rotation of the reference axes and introduces cross coupling, or "cross talk," between  the elevation and azimuth angle-tracking loops. Cross talk affects the stability of the tracking  and might result in an unwanted nutating motion of the antenna. In conventional tracking-  radar applications the phase change introduced by the feedback-loop filter should be less than  loQ, and in some applications it should be as little as 2".1° For this reason, a tilter with a sharp  attenuation characteristic in the vicinity of the conical-scan frequency might not be desirable  because of the relatively large amount of phase shift which it would introduce. 
 The dynamotor suffers from poor regulation. Furthermore, varia- tions ininput voltage may beasgreat as10percent. The dynamotor. 
 1 32. See Sec. 12.10 of rd. 
 ART 34!,/ OSCILLATOR PERFOR MANCE AND THE STRIN 
 Atypical narrow-band video amplifier and amarker signal mixer areincluded forcompleteness. Incoming video signals of8to10volts areamplified byV6and applied tothe cathode ofthe CRT. The tube VT.provides d-crestoration toassure the proper operating level. 
 However, since the radar images are due to microwave reflectivity,  not optical reflectivity, the interpreters must understand the differences and that  the images at the different wavelengths are, in fact, complementary. Moreover, the  geometrical distortions for radar images are those of a side-looking range measure - ment system, whereas those of aerial photos are those of a down-looking angle  measurement system—a difference that the interpreter must understand. At low  grazing angles, the distortions are small for radar, but at low incidence angles, they  are large. 
 Mem. 560,  Aug. 1, 1957, Culver City, Calif. 
 VAL $4 TT BETWEEN THE TRANSMISSION OF A SIGNAL AND RECEPTION OF THE TARGET ECHO )T THEN  CALCULATES THE RANGE SUM AS  24   22    C$4TT ! TRANSMITTER 
 Several conclusions may be derived from the various studies of errors described above  and from Sec. 7.8. For array antennas the following seem to apply:  I. 
 ETERS RELATING ELEMENTS OF A BREAKING WAVE SCENE TO WIND SPEED 7HITECAP DENSITY IS A VISIBLE TRACER OF BREAKING WAVE ACTIVITY AND HAS A POWER 
 3 -ODES  2ADAR -ODES02& K(Z 0ULSE7IDTHMSEC $UTY#YCLE 0ULSE#OMP2ATIO&REQ,OOKS0ULSES0ER #0)4RANSMITTED"ANDWIDTH-(Z 4OTAL0ULSES  IN 4 /4 2EAL 
 (6.7): GD = 4TrA6A2 (6.8) where Ae is the effective aperture or capture area of the antenna, less than the physical aperture A by a factor pa usually called the aperture efficiency. Ae = paA (6.9) This aperture efficiency would better be called aperture effectiveness because it does not involve RF power turned into heat; i.e., it is not a dissipative effect but only a measure of how effectively a given aperture is utilized. An antenna with an aperture efficiency of, say, 50 percent (pa = 0.5) has a gain 3 dB below the uniformly illuminated aperture gain but does not dissipate half the power in- volved. 
 WAY  
 36 HOW RADAR WORKS  inertia, and we can start it right at the beginning of the  line at full speed, stop it effortlessly at the end, and send  it back again at the same speed. If we adjust it thus, at  constant speed all along the line, we can regard it as a  true scale. We should be quite justified in marking and  subdividing the whole scale into miles, starting at o and  ending with 186. 
  A      WHERE A IS OBTAINED BY SOLVING THE BISTATIC TRIANGLE  FOR EXAMPLE  BY  USING MONO 
 Accordingly, Figure 16.28 shows an earlier  summary based mostly on X-band data. One should be cautious in using this data, but  the figure gives a feel for the overall variations. Figure 16.29 is a similar presentation  for near-vertical data.132 Calibration of the systems was good, but the antenna effect  discussed in Section 16.5 makes the values from 0 to 5° low. 
 I RE Trans .. vol. AP-5. 
 6. Conclusions This article proposed a novel MPS SAR mode and a method to process MPS SAR data together with parameter selection criteria that can be used to optimize system design. Based on the MPS SAR mode, this is a novel application to suppress azimuth sidelobes using some of the existing algorithms, which were already adjusted to meet the new mode. 
 Apr.21-23.1975.IEEEPubli­ cation75CHO938-1AES. 127.Bearse,S.V.:PlanarArrayLooksThrough LenstoProvide Hemispherical Coverage. Microwal'es, vol.14.pp.9-10,July,1975. 
 ING AMPLITUDE WEIGHTING AND DISPLAY COMPRESSION  AS HAS BEEN DONE IN THIS IMAGE )NTEGRATION OF MULTIPLE )3!2 IMAGES DRAMATICALLY IMPROVES QUALITY !IR 
 INTERVAL RATIO &)'52%  6ELOCITY RESPONSE CURVE THREE 
 13.3 SEA CLUTTER 3  The echo from the surface of the sea is dependent upon the wave height, wind speed, the length  of time and the distance (fetch) over which the wind has been blowing, direction of the waves  relative to that of the radar beam, whether the sea is building up or is decreasing, the presence  of swell as well as sea waves, and the presence of contaminants that might affect the surface  tension. The sea echo also depends on such radar parameters as frequency, polarization.  grazing angle, and, to some extent, the size of the area under observation. 
 BAND RADARS BEGAN DURING 7ORLD 7AR ))  WHICH IS WHY BOTH + U AND +A BANDS WERE LATER INTRODUCED 4HE RADAR ECHO FROM RAIN CAN LIMIT THE CAPABIL 
 The tube was given its name in the  very early days of electron research, certainly before  radar was dreamed possible, and when all manner of  rays were being discovered and tested. ‘X-rays,’ ‘gamma  rays, and ‘anode rays’ were the labels given to emana~  tions from various forms of tubes, and the name ‘cathode  ray’ was then appropriately given to the type of valve  in which ‘rays’ from the heated cathode were caused to  display their presence on a fluorescent screen. But  obviously what we are displaying are not ‘rays’ in the  normal sense, but fluorescence set up by electrons shot  off from a heated cathode; and therefore it is just as  correct to describe an ordinary radio valve and quite a  number of similar devices as ‘CRT.’ They are all tubes  which utilize the flow of electrons from a heated cathode. 
 When the MTI performance is limited by the antenna scanning fluctua-  tions, Shrader8 suggests letting Voc = 6 dB. (Although not stated by Shrader, it seems this  value is for a single pulse.) The improvement factor is the preferred measure of MTI radar  performance.  Still another term sometimes employed in MTI radar is the intercllctter visibility. 
 At each element the signal is heterodyned in a mixer with  the signal from a single series-fed array at frequency f, to provide the elevation phase 4,. The  sum signal at frequency f, + f2 is used as the carrier frequency. It has the proper phase 4, + 9,  at each element to steer in the two directions. 
 BEAM SCANNING IS PERFORMED IN ELEVATION 4HE TRANSMISSION UTILIZES TWO TIME 
 IET Radar Sonar Navig. 2012 ,6, 627–637. [ CrossRef ] 25. 
 POWER TO CLUTTER 
 10.7. All practical integration techniques  ernploy some sort of storage device. Perhaps the most common radar integration method is  tlic catliode-ray-tube display combined wit11 the integrating properties of the eye and brain of  tlic radar operator. 
 When the footprint is smaller, more variability occurs. This is shown in Fig. 12.28 from a study of the variation of scatter observed by SIR-BTime of day Day Day Day Day Night Night Night NightPolarization V V H H V V H HFrequency range, GHz 1-8 13-17 1-8 13-17 1-8 13-17 1-8 13-17Constant A,dB -10.0 0.02 -11.9 -6.6 -10.0 -10.9 -10.5 -16.9Angle slope B, dB/° -0.29 -0.37 -0.25 -0.31 -0.33 -0.13 -0.30 -0.024Frequency slope C, dB/ GHz 0.052 -0.50 0.55 0.0011 -0.32 0.70 0.20 1.036Slope correc- tion D, dB/ (° • GHz) 0.022 0.021 0.012 0.013 0.033 0.00050 0.027 -0.0069MEAN SCATTERING COEFFICIENT a° (dB) based on 1975 data based on 1976 data Model based on extrapolationfor0 = 80°f>6GHz . 
 14.8  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 Figure 14.6 is the RCS pattern of a 39 l long, 15 ° half-angle ogive recorded for hori - zontal polarization (incident electric field in the plane of the ogive axis and the line of  sight). The large lobe at the right side of the pattern is a specular echo in the broadside  sector, and the sequence of peaks at the left side is the contribution of the surface trav - eling wave near end-on incidence. Note that the RCS is extremely small (not measur - able in this case) at precisely end-on incidence. 
 F. Gabriel, “Adaptive processing array systems,” Proc. of the IEEE , vol. 
 AES-15,  pp. 37a;,396, May, 1979. ,  104. 
 STATE DEVICES EG  -%3&%4  WHERE INCREASED DYNAMIC RANGE IS REQUIRED 4HE RESULTING OUTPUT SIGNAL FREQUENCIES F ,   F2 AND F, n F2  ARE THE SUM AND DIFFERENCE  OF THE TWO INPUT FREQUENCIES )N PRACTICE  ALL MIXERS PRODUCE UNWANTED INTERMODULATION . È°£Ó  2!$!2 (!.$"//+  SPURIOUS RESPONSES WITH FREQUENCIES   NF,  MF2 WHERE M AND N ARE INTEGERS   AND THE  DEGREE TO WHICH THESE SPURIOUS PRODUCTS IMPACT THE RADAR PERFORMANCE DEPENDS UPON THE  TYPE OF MIXER AND THE OVERALL RADAR PERFORMANCE REQUIREMENTS !NALYSIS OF MIXER SPURI 
 Hayes: Some Properties or Radar Returns from Rain at 9.375, J5.  70. and 95 Gllz, IEEE 1975 111/('/'llatimwl Radar Confi_,rence, Apr. 
 One form ofstandard attenuator utilizes thisfact.. i?EC. 11.3] WAVEGUIDE 401 too gradual anattenuation ofthe higher modes inevitably excited at discontinuities such asT-junctions and diaphragms. 
 D. Sahr, “Remote sensing with passive radar at the University of Washington,” IEEE Geoscience  and Remote Sensing Society Newsletter , pp. 16–21, December 2005. 
 Target classiﬁcation using the deep convolutional networks for SAR images. IEEE T rans. Geosci. 
 "  #   #                 .   -4) 2!$!2  Ó°Ç 0ART OF THIS IMPROVEMENT WAS DUE TO THE USE OF DOPPLER FILTER DESIGNS UTILIZING  EIGHT PULSES  INSTEAD OF JUST THREE FOR THE -4)  AND PART WAS THE RESULT OF ALLOWING A  LARGER DYNAMIC RANGE INTO THE -4$ PROCESSOR AND RELYING ON A CLUTTER MAP TO SUPPRESS RESIDUES IN REGIONS WHERE THE CLUTTER LEVEL EXCEEDS THE MAXIMUM CLUTTER SUPPRESSION OF THE RADAR 4HE BLOCK DIAGRAM OF THE -4$ )) SIGNAL PROCESSOR IS SHOWN IN &IGURE  0ARALLEL  PROCESSING CHANNELS ARE PROVIDED FOR MOVING TARGETS THROUGH THE TWO 
 May 4, 1964.  40. Bean, B. 
 21. Barrick, D. E., J. 
 The curve of Fig. 13.10 illustrates the behavior of land clutter at low graring angles.'"he  value of a0 decreases with decreasing grazing angle until, in this case, at about 3.5" the value of  a0 actually increases as the grazing angle is lowered. This behavior is said to be due to the  stronger backscatter from vertically oriented structures (trees, buildings, crops) as the grazing  angle approaches zero. 
 With a long coded-pulse signal, the  repeater can also put energy into the radar ahead of the compressed pulse, or coincident with  it, if sufficient power is used to overcome the mismatch of the repeater signal to the pulse-  compression filter.  In spite of its limitations, pulse compression has been an important part of radar systems  technology.  Spread spectrum. 
 BAND  ANTENNA WILL HAVE A SMALLER BEAMWIDTH THAN AN 3 
 OFFS  IN MOST CASES  CONVERGING ON SCHEMES IN WHICH n RECEIVE BEAMS ARE FORMED WITHIN A BROADER TRANSMITTED BEAM FOOTPRINT 4HE REDUCED TRANSMITTING ANTENNA GAIN MAY BE COMPENSATED BY INCREASING POWER OR COHERENT PROCESSING TIME %VEN UNDER BENIGN CONDITIONS  THE IONOSPHERE SELDOM SUPPORTS HIGHLY COHER 
 The local oscillator of the noncoherent radar does not have  lo he as frequency-stable as in the coherent MTI. The transmitter must be sufficiently stable  over the pulse duration to prevent beats between overlapping ground clutter, but this is not as  severe a requirement as in the case of coherent radar. The output of the amplitude detector is  followed by an MTI processor such as a delay-line canceler. 
 TO 
 They are also called emitter  locators . Target location is by means of combined angle measurements from each site  (e.g., triangulation) or time-difference-of-arrival and/or differential doppler measure - ments between sites (e.g., multilateration). These systems usually are not designed to  detect and process the echoes from targets illuminated by the transmitter. 
 Available Scattering Information. Prior to 1972 the lack of coordinated research programs over the necessary long period resulted in only one really usable set of measurements, that at Ohio State University.2'4 Since that time extensive measurements have been made from trucks and helicopters by the University of Kansas,6'7 a group in the Netherlands,8 and several groups in France.9 These measurements concentrated especially on vege-FIG. 12.1 Geometry of the radar equation. 
 BAND DUAL POLARIZATION RADAR MEASUREMENTS v  "ULL !-3  VOL     PP n    & &ABRY  # &RUSH  ) :AWADZKI  AND ! +ILAMBI  h/N THE EXTRACTION OF NEAR 
 136. B. L. 
 So more current flows to G2, which  consequently becomes less positive, because of the  increased voltage drop across Rr. The second difference  from the usual pentode arrangement is that.a condenser  . ‘IMPOSSIBLE’ CIRCUITS 95  is connected between G2 and G3. 
 WIDTH OF THE DOPPLER FILTERS THAT OCCURS BECAUSE OF FILTER SIDELOBE WEIGHTING 4HE LOSS CAN ALSO BE ACCOUNTED FOR BY AN INCREASE OF THE DOPPLER FILTER NOISE BANDWIDTH INSTEAD OF AS A SEPARATE LOSS $OPPLER &ILTER 3TRADDLE ,OSS  4HIS LOSS IS DUE TO A TARGET NOT ALWAYS BEING IN THE  CENTER OF A DOPPLER FILTER )T IS COMPUTED BY ASSUMING A UNIFORMLY DISTRIBUTED TARGET DOP 
 Rept.  R81-152, Santa Barbara, CA, 1981.  83. 
 For this reason, the extrac-  tion of the higher-order modulation frequencies is not practical with a stationary target, such  as in an altimeter.  In order to use the properties of the Bessel function to obtain isolation in an FM-CW  altimeter, when tlie doppler frequency is essentially zero, the role of the doppler frequency shift  may be artificially introduced by translating tlie reference frequency to some different value.  This rriiglit he accor~iplistied with a single-sideband generator (frequency translator) inserted  hetwcerl tllc directional coupler and tile RF rnixer of Fig. 
 A typical pulse amplitude time function is  a slowly varying echo amplitude.32 The low-frequency amplitude noise contributes the  largest portion of the noise modulation density and is concentrated mainly below about  10 Hz at X band. The amplitude-noise spectrum is similar for both large and small  targets. This is because the rate of relative range change is a function of both angular  yaw and distance from the center of gravity of the aircraft. 
 The receiver noise figure is measured relative to a reference tem- perature TQ = 290 K (approximately room temperature), and the factor kT0 be- comes 4 x 10~21 W/Hz. The minimum detectable signal in the radar equation can be written 5min = MoBFn^ (1.4) Sometimes the factor T0Fn is replaced with J5, the system noise temperature. The above discussion of the radar equation was in terms of the signal power. 
 Nevertheless, a single value of cross section is sometimes given for specific aircraft targets for  use in computing the radar equation. There is no standard, agreed-upon method for specifying  the single-valued cross section of an aircraft. The average value or the median might be taken. 
 RECEIVERS, DISPLAYS, AND DUPLEXERS 347  In making a measurement of the receiver noise-figure, the noise source or signal generator  is usually inserted by a directional coupler ahead of the duplexer and other RF components so  that the overall noise-figure of the system is measured rather than that of the receiver alone.  h1:tny radar superheterodyne receivers do not employ a low-noise RF amplifier. Instead, the  first stage is simply the mixer. 
  
 It is difficult to phase or fre - quency modulate the waveform of a magnetron, as is needed for pulse compression.  Thus, power amplifiers are almost always used for pulse compression applications.  Magnetrons are not stable enough to be suitable for very long pulses (e.g., 100 µs), and  starting jitter limits their use at very short pulse widths (e.g., 0.1 µs), especially at high  power and at the lower frequency bands. 
 STATE DEVICES IS INFLUENCING 3"2 3!2 DESIGN 2ADARS BUILT AROUND 474!S HAVE ESTABLISHED IMPRESSIVE LONGEVITY RECORDS  WITNESS 2!$!23!4 
 26. Gostin, J. J.: The GE592 Solid State Radar, EASCON '8O Rec., pp. 
 These simplified versions of the ·radar equation do not adequately describe the perfor­ mance of practical radar. Many important factors that affect range are not explicitly included.  In practice, the observed maximum radar ranges are usually much smaller than what would be  predicted by the above equations, sometimes by as much as a factor of two. 
 Actual antenna patterns produce somewhat less favorable transients than the gaussian shape. Limiting in the receiver is equivalent to altering the shape of the beam.9 For any antenna pattern there is a definite limitation on the scanning speed of a narrow-beam antenna. Actually, mechanical limitations usually pre- vent trouble except with the very slowest targets, but with nonmechanical scan- ning methods degradations may occur. 
 Vector Wind Retrieval.  The normalized backscatter coefficient s  0 from a wind- roughened oceanic surface depends foremost on the radar’s wavelength, the local angle  of incidence, and the polarization, respectively. The wind parameters to be estimated  are its speed, the relative angle in the horizontal plane between the wind direction,  and the radar line-of-sight. 
 Hence. the optimum antcnna heights might vary.  Theoretical models of propagation in evaporation ducts confirm tlic gcncral experimental  observations presented above.I7 When multiple modes of propagation arc trnppcd in thc i!t~cl. 
 TIVELY BROADBAND 4HE DEGREE OF TRACKING REQUIRED FOR SIDELOBE CANCELER OPERATION WAS PREVIOUSLY ACHIEVED BY PROVIDING MATCHED SETS OF FILTERS WITH TIGHTLY TRACKING AMPLITUDE AND PHASE RESPONSES -ODERN DIGITAL SIGNAL PROCESSING ALLOWS THE CORREC 
 F. M. Henderson and A. 
 The two RFMs  are independently generated for the main and  auxiliary signals and the testing of the main and auxiliary received power values is  performed for all range cells and all doppler filters. This is different from a conven - tional SLB approach (such as the one illustrated in Figure 24.1) operating so that  if interfering/repeater jammer power is detected at a particular range cell, then that  range cell has to be effectively blanked. The RFM-based SLB logic greatly reduces  ch24.indd   13 12/19/07   6:00:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Bussey, E. J. Fremouw, and Sa. 
 When scanning interrupts thepicture, thescreen must have sufficient persistence (’(afterglow”) topermit observations and measurements on theechoes and insofaraspossible tofurnish acontinuous picture. On theother hand, theimage must not persist solong astocause confusion onachanging picture. Interms ofthe scanning rate, three cases may beconsidered: 1.Cases inwhich little ornopersistence isneeded, either because the frame time isless than theretentivity time oftheeye (about ~see) orbecause observations are made inthe absence ofscanning. 
 The update interval typically ranges from a minimum of the transmitter's interpulse period to a maximum of the transmitter's antenna scan period. The former usually requires a dedicated link between transmitter and re- ceiver; the latter can be implemented whenever the transmit beam scans past the receive site, given an adequate LOS, and is sometimes called direct breakthrough.™ Temperature-controlled crystal oscillators can often satisfy these requirements. However, when direct-breakthrough time synchronization is used, multipath and other propagation anomalies, as well as radio-frequency interference (RFI), will de- grade the accuracy of updating. 
 Specular reflection is defined as reflection from a smooth plane and obeys the  Fresnel reflection laws.53 At normal incidence, the specular-reflection coefficient is  therefore  ΓRg g=− +η η η η0 0  where h0 and hg are the intrinsic impedances of air and earth, respectively. The fraction  of total incident power specularly reflected from a rough surface is7  eh −2 22( )πσ λ/  where  sh = standard deviation of surface height variations, and  l = wavelength Since this proportion is down to 13.5% when sh = l/2p and to 1.8% when  σ λ πh=/( ), 2 2  significant specular reflection is seldom found for the centimeter  wavelengths generally used for radar. Nevertheless, a simplified model like this is  convenient for some purposes. 
 For example, the digital data rate for the ERS-1/2 and  RADARSAT Earth-observing SARs is on the order of 120 Mbit/s. Newer designs  claim up to 400 Mbit/s. Since the Magellan  objective was to image a substantial por - tion of the surface of the entire planet at 120-m resolution within the length of the  primary mission, the DSN data-rate capability emerged as the toughest requirement  on the entire system. 
 This radar uses 25,344 X-band solid-state transmit/receive modules in  the phased array. X-Band Radar (XBR).  The nine-story-high XBR is the world’s largest X-band  radar, weighing four million pounds (see Figure 13.50). 
 OF 
 .. Free - space coveroge conlour -7 PROI'A(;A.I'ION 01.' RADAR WAVES 447  (b) vertical polarization  eartli. Lobing. 
 TO 
 Tragically, Blumlein andtwo key EMI associates (C O Brown and F Blythen), together with ﬁve RAF crew, were killed testing the prototype magnetron H 2S in a Halifax bomber in the Wye Valley on 7 June 1942 [ 2,3]. However, work on the manufacture of H 2Sa tE M I continued, led by E L C White, for the remainder of the war. During 1942, various approaches to improving the performance of ASV were investigated. 
 POLARIZATION MODE IS ACTUALLY  ALTERNATING 
 'RADIENT - 
 9.2 NOISE FIGURE  In Sec. 2.3 the noise figure of a receiver was described as a measure of the noise produced by a  practical receiver as compared with the noise of an ideal receiver.1.2 The noise figure I\ of a  linear network may be defined as  F = Sin/Nin = Nout  " SoutfNout kTo BnG  where Sin = available input signal power  Nin = available input noise power (equal to kT0 Bn)  S0u, = available output signal power  N0u, = available output noise power (9. l)  "Available power" refers to the power which would be delivered to a matched load. 
   -4) 2!$!2  Ó°ÇÇ IS SHOWN IN &IGURE  4RANSMITTER NOISE WILL BE USED IN THE FOLLOWING DISCUSSION  TO REPRESENT ALL POSSIBLE SYSTEM INSTABILITIES THAT CREATE NOISE 
 However, the airport surface detection radar for the location and control of ground traffic at airports is at Ku band because of the need for high resolution. The disadvantages that characterize this band are not important in this particular application because of the short range. Millimeter Wavelengths (above 40 GHz). 
 WATER CONTENT BY RADAR v  * -ETEOROL    VOL   PP n     ( + 7EICKMANN AND ( * AUFM +AMPE  h0HYSICAL PROPERTIES OF CUMULUS CLOUDS v  * -ETEOROL   VOL   PP n    + , 3 'UNN AND 4 7 2 %AST  h4HE MICROWAVE PROPERTIES  OF PRECIPITATION PARTICLES v  1 * 2  -ETEOROL 3OC  VOL   PP n    * 7 2YDE AND $ 2YDE   !TTENUATION OF #ENTIMETER 7AVES BY 2AIN  (AIL  &OG  AND #LOUDS    7EMBLEY  %NGLAND 'ENERAL %LECTRIC #OMPANY    " 2 "EAN AND 2 !BBOTT  h/XYGEN AND WATER VAPOR ABSORPTION OF RADIO WAVES IN THE ATMO 
 UHF wind profilers operating at 915 MHz in the U.S. and 1200–1300 MHz   ch19.indd   39 12/20/07   5:39:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 13.7), inwhich circuit thelatter tube isnormally off. After theflip-flop hasbeen triggered, the current through VWlifts the cathode ofVia,cutting this tube offbyan amount greater than the signal level. The flip-flop istimed toreverse shortly before the next desired signal isexpected. 
 Wide-angle SAR imaging. Proc. SPIE 2004 ,5427 , 164–175. 
 The frequency coverage for the four ranges of the transmitter and receiver for Lucero Mk. II are shown in table 6.2. Any receiver range and any transmitter range doi:10.1088/978-1-6432-7066-1ch6 6-1 ªMorgan & Claypool Publishers 2018. 
 R., and C. M. Rader (eds.): "Digital Signal Processing," IEEE Press, New York. 
 The individual resolved spikes can  cause false alarms. Raising the receiver threshold level to reduce the false alarms can result  in a significant loss in sensitivity to desired targets. This negates the benefit of the increased  signal-to-clutter ratio achieved by high resolution as expressed by Eq. 
 B. L. Lewis and F. 
 Purves: Radar Imagery of Oil Slicks, IEEE Trans., vol. AES-9, pp. 630 636,  September, 1973. 
 W.: Radar Technology Applied to Air Traffic Control, IEEE Trutrs., vol. COM-21,  pp. 591-605, May, 1973. 
 40, no. 7, pp. 1670–1680. 
 As discussed in Sec. 2.10, the radar pulse repetition frequency (prf) must be  low enough to avoid range ambiguities and multiple-time-around echoes. An additional con-  straint on the prf occurs in a synthetic aperture radar. 
 The transmitter unit included a meter to monitor thecurrent taken by the valves. Typically the valves took 1.5 A each whilst oscillating. With a pulse length of 2.5 μs and a PRF of 400 c/s the average current consumption should have been about 3 mA and the average current was then an indication ofPRF. 
 TORS  TYPICALLY FORM A TRIPOD  AS SHOWN IN &IGURE  3TRUT SCATTERING IS A COMPLEX  PHENOMENA THAT DEPENDS ON STRUT SIZE  STRUT GEOMETRY  FIELD POLARIZATION  AND OTHER FAC 
 Although the boundaries of the radar receiver are somewhat arbitrary, this chapter  will consider those elements identified in Figure 6.1 as the receiver. The radar exciter  generates the transmit waveforms as well as local oscillator (LO), clock, and timing  signals. Since this function is usually tightly coupled to a radar receiver, it is also  shown in Figure 6.1 and will be discussed in this chapter. 
 Asthevoltage toberegulated is 115 volts alternating current, rectification and voltage-dropping are necessary. Rectification isprovided byaselenium dry-disk rectifier, inseries with a“globar” resistor which provides some temperature 1Although the35-watt carbon-pile regulator can bemade tooperate over arange ofresistance from 2to60ohms, ithasbeen found desirable touse onlytherange from 2to30ohms since thehigh-resistance endoftherange hasatendency tobeunstable. 2Mr.C,.Neild, “(?arhon.pile Regulators for.kircraft, ”AIEE Transactions, 63, 839-842 (November. 
 Bylettingrbecomeverylarge(essentially infinite), Fig.11.10mayalsobeusedtorepre­ sentaCWradar.Similarly, bylettingrbeverysmall(infinitesimal), thediagram appliestoan impulse radar. Periodic pulsetrain.Consider asinusoid modulated byatrainoffivepulses,eachofwidthr. Thepulse-repetition peri09isTp,andtheduration ofthepulsetrainis1d(Fig.1l.l1a).The ambiguity diagram isrepresented inFig.ll.llb.Withasinglepulsethetime-delay- and frequency-measurement accuracies dependononeanotherandarelinkedbythepulsewidthr. 
 76-85, August, 1962.  67. Jolinson. 
 Figure 11.5 illustrates the scattering behavior of very thin dielectric cyl- inders. Integral Equations. Maxwell's equations may also be manipulated to gener- ate a pair of integral equations (known as the Stratton-Chu equations24), E8 = ${ikZ0(n x H)I)I + (n x E) x Vi|/ + (n • E)Vi|/}dS (11.9) H8 = #{ - ikYQ(n x E)<|i + (n x H) x Vi|/ + (n • H)Vi|i}dS (11.10) where n is the unit surface normal erected at the surface patch dS and the Green's function fy is ty = eikr/4Tir (11.11) The distance r in Eq. 
 Observation of reflected sunlight from rippled water, from roads, and from other  smooth surfaces leads to the postulation of a facet theory.54,55 The only sunlight reach - ing the observer from smooth surfaces such as water is that from facets for which angle  of incidence equals angle of reflection. Thus, the observed light may be described by  methods of geometric optics . When geometric optics is used to describe radar scatter, the surface of the ground  is represented by small flat-plane segments. 
   %,%#42/.)# #/5.4%2 
 Mechanical movement limits the acquisition speed of the SAR image. There is a need for faster acquisition time as it plays an important role in correcting rapidly varying atmospheric effects. Also, a fast imaging radar can extend the applications to the measurement of vibrations of large structures. 
 The value of N' is chosen to optimize performance in the face of initial errors or disturbances which would increase miss distance: heading error, target maneuver, system biases, and noise. For example, increasing values of N' cause early correc- tion of collision course errors, reserving the missile's maneuver capability near inter- cept for countering target maneuvers and noise. Too high a value of TV', however, re- sults in too great a sensitivity to noise inputs, especially glint, which increases with decreasing range. 
  AND K0    
 Navy )OSCILLATORSBASELINE SIGNAL RECEPTION DETECTIONALERT SIGNAL RECEPTION AND THRESHOLD DETECTION I kHz REFERENCE PHASE CONDITIONING I kHz BASELINE PHASE ADDAS ENCODER DIGITAL DATA  SET  TELEPHONE LINES TO NAVSPASUR HQLOGICAL COMBINERACTUATIONI kHz PHASE SIGNAL (one for each bseline) COMMAND CONTROLS 2 PILOT, RESYNCHRONIZATION CALIBRATION COMMAND21 COMBINER SOLUTION,BASELINE PHASE DATA,ALERT, CALIBRATION1 ch23.indd   12 12/20/07   2:21:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 
 Array calibration  waveform Description  250 JIS, FM  10 /IS  250 /IS, FM  \ /tS  40-pulse burst of 125- JIS pulses; burst dur­ ation I s  40-pulse burst of 25-J~S  pulses; burst durn­ tion 0.2 s  40-pulse burst of 5-;is  pulses, stepped fre­ quency; burst dura­ tion 1.2 ms  60 JIS Primary function  Long-range search and  track acquisition  Short-range search and  track acquisition  Long-range track  Short-range track and  short-range SLBM  search  Extended-range I rack  and signature  Intermediate doppler  and signature  Precision-range  tracking  Transmitter and re­ ceiver module cali­ bration . TIIE Fl.l:CTRONICAI.LY STEERED PHASED ARRAY ANTENNA IN RADAR 325  ing on the compu!er resources, hence it is necessary to exclude information that is of no  interest to the system. Such unwanted inrormation may be from clutter, interference, or  jamming. 
 DELAY SYSTEM  THE DISPLACEMENT HAS TO BE HELD TO  FOR A   D" PERFORMANCE LIMIT Î°xÊ * /",  "/" ÊÊ  " * 
 Rept. 2591-1-H, July 1959. 70. 
 oflargeclutterreturnscaneffectively appearasalargestepinputtothefilterwiththeresult thatsevereringingisproduced inthefilteroutput.Theringingcanmaskthetargetsignaluntil thetransient response diesout.Inthe.usualsurveillance radarapplication, thenumber of pulsesfromanytargetislimited,hence'theoperation ofanMTIfilterisalmost'alwaysinthe transient stateformostrecursive filters.16Ithasbeensaidthatafrequency response character­ isticwithsteepsidesmightallow15to30ormorepulsestobegenerated atthefilteroutput becauseofthefeedback.14Thismightmakethesystemunusable insituations inthepresence oflargediscrete clutter,andwhereinterference fromnearbyradarsorintentional jamming is encountered. Thepoortransient response mightalsobeundesirable inaradarwithastep-scan antenna (asinaphasedarray),sincetheseextrapulsesmighthavetobegatedoutafterthe beamismovedtoanewposition. Inthestep-scan antenna ithasbeensuggested thatthe undesirable transient effectscanbemitigated byusingtheinitialreturnfromeachnewbeam position, oranaverageofthefirstfewreturns,toapplyinitialconditions totheMTIfilterfor processing theremaining returnsfromthatposition.15Theclutterreturnscanbeapproxi­ matedbyastep-input equalinmagnitude tothefirstreturnforthatbeamposition sothatthe steady-state valuesthatwouldnormally appearinthefiltermemory elements afteran infinitely longsequence oftheseinputscanbeimmediately calculated andloadedintothefilter tosuppress thetransient response. 
 TRACK ASSOCIATION IS USUALLY DOMINATED BY THE MORE DIFFICULT CONDITIONS OF CLOSELY SPACED TARGETS OR CLOSELY SPACED TARGETS AND CLUTTER &IGURE  SHOWS A COMMON SITUATION FOR CLOSELY SPACED TARGETS ANDOR CLUTTER 4HREE ASSOCIATION GATES ARE CONSTRUCTED AROUND THE PREDICTED POSITIONS OF THREE EXISTING TRACKS 4HREE DETECTIONS ARE MADE  BUT ASSIGNMENT OF THE DETECTIONS TO THE TRACKS IS NOT OBVIOUS TWO DETECTIONS ARE WITHIN GATE  THREE DETEC 
 1976.  52. Ulaby, F. 
 STRATE 2EACTIVE COMPONENTS THAT ARE NECESSARY AS IMPEDANCE 
 89. C'ror~cy. J : ('lr~ttcr. 
 (From Whicker and Jones,156 courtesy IEEE.) . THE ELE(TRONIC'ALLY STEERED PHASED ARRAY ANTENNA IN RADAR 293  saturation before a new value of phase shift can be applied. The phase shift of a ferrite device is  especially sensitive to temperature. 
 Inthis case approximately –800 volts should be applied tothe cathode and 1000 volts tothe third anode. The second grid and the focus electrode arekept atsuitable intermediate voltages. Auxiliary facilities, such asrange-measuring circuits orsweep delays, can beadded, butwhen these aredesired itisusually preferable touseamore elegant basic indicator. 
 Although aphasecomparison isapartoftheamplitude-comparison-monopulse radar, theangular-error signalisbasically derivedbycomparing theechoamplitudes fromsimulta­ neousoffsetbeams.Thephaserelationship between thesignalsintheoffsetbeamsisnotused. Thepurpose ofthephase-sensitive detector istoconveniently furnishthesignoftheerror signal. Ablockdiagram ofamonopulse radarwithprovision forextracting errorsignalsinboth elevation andazimuth isshowninFig.5.9.Theclusteroffourfeedsgenerates fourpartially overlapping antenna beams.Thefeedsmightbeusedwithaparabolic reflector, Cassegrain antenna, oralens.Allfourfeedsgenerate thesumpattern.Thedifference patterninoneplane isformedbytakingthesumoftwoadjacent feedsandsubtracting thisfromthesumoflhe othertwoadjacent feeds.Thedifference patternintheorthogonal planeisobtained byadding thedifferences oftheorthogonal adjacent pairs.Atotaloffourhybridjunctions generate the sumchannel, theazimuth difference channel, andtheelevation difference channel. 
 The antenna feed is located at the focal point to receive maximum energy from a target on axis. An amplitude-comparison monopulse feed is designed to sense any lateral dis- placement of the spot from the center of the focal plane. A monopulse feed using the four-horn square, for example, would be centered at the focal point. 
 PERTURBATION METHOD ORIGINALLY PROPOSED BY  2ICE BECAME THE MOST POPULAR WAY TO DESCRIBE OCEAN SCATTER )TS APPLICATION TO LAND  SCATTER WAS NOT FAR BEHIND 4HE TERM  "RAGG SCATTER IS OFTEN USED TO DESCRIBE THE MECHANISM FOR THE SMALL 
 Note that the distance to the radarhorizon is the distance at which the radar rays graze the surface of the earth. In the preceding discussion standard atmospheric conditions were assumed. The standard atmosphere is a hypothetical vertical distribution ofatmospheric temperature, pressure, and density which is taken to berepresentative of the atmosphere for various purposes. 
 12. Moore. R. 
 Unfortunately. the thin skin required for good electrical properties is not consistent with good  mechanical properties. This limits the size and the frequency of operation of thin-wall rigid  rad om cs. 
 19.42 reduces to  var(ˆ)f Tf=σ π40 (19.43) Noting that var(ˆ) ( / )var(ˆ), v f =λ22 we can write  var(ˆ)v Tv=λσ π80 (19.44) ch19.indd   22 12/20/07   5:38:58 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 
 SHARED BASIS 4HERE ARE MANY OTHER WAYS TO DESCRIBE RADARS  INCLUDING LAND  SEA  AIRBORNE  SPACE 
 The development of a single track file by use of the total  available data from all radars reduces the likelihood of a loss of target detections as might be  caused by antenna lobing, fading, interference, and clutter since integrated processing pernlits  the favorable weighting of the better data and lesser weighting of the poorer data.  REFERENCES  1. Dunn, 3. 
 Blinchikoff, “Range sidelobe reduction for the quadriphase codes,” IEEE Trans. Aerospace  and Electronic Systems, vol. 32, no. 
 21.pp.314-318,1966. 127.ScIby,R.P.:PowerDrives,chap.9of"Mechanical Engineering inRadarandCommunications," C. J.Richards (ed.),VanNostrand Reinhold Co.,NewYork,1969. 
 LAUNCH CALIBRATION AND OPERATIONS v IN  0ROCEEDINGS OF THE )%%% )NTERNATIONAL 'EOSCIENCE AND  2EMOTE 3ENSING 3YMPOSIUM  $ENVER  #/    ' , 3TEPHENS AND $ ' 6ANE  h4HE #LOUD3AT MISSION v IN  0ROCEEDINGS )%%% )NTERNATIONAL  'EOSCIENCE AND 2EMOTE 3ENSING 3YMPOSIUM  4OULOUSE  &RANCE    ! 2OITMAN  $ "ERRY  AND " 3TEER  h3TATE 
 Thebackscatter fromsnow-covered terraindepends onthenatureoftheunderlying surfaceaswellasthedepthandwetnessofthesnow.Radarenergycanpropagate insnowwith butmoderate attenuation sothatthebackscatter willbedetermi,ned bytheenergyreflected fromthesnow'ssurfaceaswellastheenergyreflected fromthesurfacebeneath thesnow.The amountofattenuation inpropagating through thesnowwillalsobeimportant. Thebackscat­ terfromsnow-covered terrainisdependent onthewetness, oramount ofliquidandsolid waterinthesnow,moresothanthethickness ofthesnow.Itwasfound,4b forexample, that 15cmofdrypowderlike snowhadnoeffectonthemeasured backscatter overthefrequency range1to8GHz.Anybackscatter contribution bythesnowwascompletely dominated by thecontribution oftheunderlying soil.With12cmofwetsnow,aOdecreased approximately 5 to10dBatgrazinganglesbetween 30and800 •At30°grazingangle,forexample, thevariation ofaOasafunction ofthewatercontentofthesnowisintherange-0.3to-0.6dB/O.lgjcmZ overthefrequency rangefromLtoCbands.Othermeasurements indicate thatthepresence of. HORIZONTAL POLARIZATION d  0 --  -10 - - a, = -20  b  O -30.1 ii  - 4 0 CITY  VTA CULTIVATED  -50 .- TERRAIN ASPHALT 71 CONCRETE  -60L. 
 Equation (11.20) is the same as Eq. (11.5) but is derived in a totally different manner. This  is a rather interesting result, for it seems to imply that the value of time delay obtained with a  straightforward method like the leading-edge technique can be as accurate as the optimum  processing technique described above. 
 Under most circumstances, the important units oftest equipment should bebuilt into theradar inaway that permits their most convenient use. Iflimitations ofweight and bulk donot permit theuse ofbuilt-in test equipment, suitable test points should beprovided to permit convenient and adequate tests tobeperformed frequently onthe important parts ofthesystem. RadarPerformance Figure.—The ratio ofP,the pulse power ofthe radar transmitter, toSmin, the power ofthe minimum detectable signal, isameasure oftheradar performance. 
 For itsmaximum value, using anotation defined belo\v, weget Subscript i–interrogation leg. Subscript r–response leg. Subscript T–transmitting components. 
 H. S. Hayre and R. 
 Ennlope detector-optimum-detector law. The function of the envelope detector is to extract  the modulation and reject the carrier. By eliminating the carrier, all phase information is lost  and the detection decision is based solely on the envelope amplitude. 
 ch04.indd   33 12/20/07   4:53:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 W.: Radar Observatio~~s of lr~sect Fligi~t, chap. 8, of" lnsect Flight," R. C. 
 Rept.   75-549, July 1975. 35. 
 5. International Telecommunication Union, www.itu.int.  6. 
 TION OF %Q   AND OF MORE GENERAL AND POWERFUL ADAPTIVE ARRAY CONCEPTS EG  '3,# GENERALIZED 3,#   #LEARLY THE EFFICIENCY OF THE ADAPTIVE ARRAY DEPENDS  ON THE NUMBER OF DEGREES OF FREEDOM DOF  AND THE ACCURACY OF RECEIVING CHAN 
 8.Lewis,B.L.,andI.D.Olin:SomeRecentObservations ofSeaSpikes,International Confert!lIce RADAR-77, pp.115-119, Oct.25-28,1977,lEE(London) Conference Publication no.155. 9.Long,M.W.:"Radar Reflectivity ofLandandSea,"Lexington Books,D.C.HeathandCo., Lexington, Mass.,1975. 10.Lewis,B.L.,J.P.Hansen,I.D.Olin,andV.Cavaleri: High-Resolution RadarScattering Character­ isticsofaDisturbed SeaSurfaceandFloating Debris,NavalResarch LtJ!Joratory ReportX131, Washington, D.C.,July29,1977. 
 By providing more than one sampling signal, multiple simultaneous beams  can be generated which can either be fixed or independently steered.  The local oscillator signals of Fig. 8.29 are derived coherently by mixing the two frequen­ ciesf1 and.f~ and filtering the desired mixer products/, + nfs, 11 = 1, 2, ... 
 The main design principles (e.g.,  selection of transmitter power, frequency, waveform, and antenna gain) as dictated by  the ECM threat are also discussed in some detail.Chapter 24 *  A list of acronyms is at the end of the chapter before the list of references. ch24.indd   1 12/19/07   5:59:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 VxTpa FIG. 16.8 Effect of platform motion on the MTI improvement factor as a function of the fraction of the horizontal antenna aper- ture displaced per interpulse period, VxTp/a. 16.4 PLATFORM-MOTIONCOMPENSATION ABEAM The deleterious effects of platform motion can be reduced by physically or elec- tronically displacing the antenna phase center along the plane of the aperture. 
 It is assumed that the width of the area Ac is determined by the azimuth beamwidth  On, but that the dimension in the range dimension is determined by the radar pulse width r  rather than the elevation beamwidth. Using the simple radar equation of Sec. 1.2, the power  C received from the clutter is  Radar(. 
 maximum radiation intensityGaverage radiation intensity   Antenna gain describes the degre e to which an antenna concentrates electromagnetic energy in a  narrow angular beam. The two parameters associated with the gain of an antenna are the directive  gain and directivity. The gain of an antenna serves as a figure of merit relative to an isotropi c source  with the directivity of an isotropic antenna being equal to 1. 
 This ismade totake the direction onthetube face that corresponds tothe instantaneous antenna orientation bysome form of electromechanical repeater. Except forthis modification inthe deflee-. 440 THERECEIVING SYSTEM—RADAR RECEIVERS [SEC. 
 While all ionospheric properties are time-varying, from  an OTHR perspective, it is useful to separate the “fast” processes or “dynamics” from  the “slow” or “structural” variability. A phenomenon is termed dynamical  relative to  a radar observation process if it occurs on a timescale commensurate with the corre - sponding process timescale, such as (i) pulse/waveform repetition interval, (ii) coherent   integration (dwell) time, (iii) scan revisit time, or (iv) mission / track lifetime.  Dynamical processes impact directly on how one should process the received signals  or perform tracking. 
 !Parameters per array face. ^Upgraded with 100-W peak power modules. high. 
 PERIODIC ANTENNA AND II   
 SCINTILLATING TARGET HAS A  PROBABILITY  OF DETECTION AT A  D" 
 1 and 21, see Figure 10a. The intersection is near subway Station A and B that are situated at the center of subsidence area. The rate of subsidence reaches up to −44.30 mm/yr. 
 EARTH 
 13. p. 39, April, 1970. 
 When the weapon is near the target,  the signal-to-jam ratio can be very unfavorable. Antenna jammer nulling is usually  required since transmitting more power to burn through may not be possible. Clearly,  the data from and to a weapon must also be sufficiently encrypted to prevent take-over  of the weapon in flight.8 Time synchronized with a radar transmission on a different set of beams and/or fre - quencies, messages are sent to one or more missiles on the fly to the targets. 
 Coherent dual polarization has not been exploited in orbital SARs  (although it is standard practice in Earth-based radar astronomy through facili - ties such as the Arecibo radar telescope58). Experience has shown that there is  relatively little added value in the phase between the like-polarized and cross- polarized returns under the condition of H or V transmit polarization. However,  an innovative alternative is to transmit circular polarization and receive coher - ently two orthogonal linearly polarized components. 
 AVERAGING #&!2  RATIO DETECTORS  LOG  INTEGRATOR  AND BINARY INTEGRATOR 2AYLEIGH  PULSE 
 280 ANTENNAS, SCANNERS, AND STABILIZATION [SEC. 95 byusing sheet-metal ribs orchannels formed bythehydropress method, and boxed inattherear asinFig. 9“8, orbyusing astamped outer frame made bythe drop-hammer method, asinthe 8-ft reflector shown in Fig. 
 J. M. Headrick, “Looking over the horizon,” IEEE Spectrum , vol. 
 Brookner, E., and T. F. Mahoney: Derivation of a Satellite Radar Architecture for Air Surveillance," IEEEEASCON '83 Conf. 
 FUNCTION PASSBAND  IT CAN SERVE AS A PRELIMINARY GUIDELINE FOR THE -4) FILTER DESIGN &)'52%  #LUTTER POWER IN TWO 
 115. Ulaby, F. T., et al.: Millimeter-Wave Bistatic Scattering from Ground and Vegetation Targets, IEEE Trans., vol. 
 TRACK SPACING /BSERVATION OF OCEANIC AND  e  4HE AVERAGE SEA LEVEL IN THE ABSENCE OF DYNAMIC PERTURBATIONS OF THE SURFACE ELEVATION DUE TO TIDES AND CURRENTS    )N THE FIELD OF OCEANOGRAPHY  MESOSCALE FEATURES HAVE SCALES  OF SEVERAL HUNDRED KILOMETERS  AS OPPOSED TO THE MUCH  LARGER BASIN SCALE THE .ORTH !TLANTIC OCEAN  FOR EXAMPLE . 
 Radar System Engineeri ng Chapter 8 – Pulse Radar  61     - Binary integration   With tapped delay line integration, accordin g to Figure 8.16, analog or digital signals are fed  into a tapped delay line, whose length corresponds to the number of hits per scan n B.  At the  output one obtains a maximum if n successive echoes are received from a target.  The exec u- tion of an analog tapped delay line can be realized by RLC bandpass resonators, RC elements,  static memory elements or mechanically circulating samplers. 
 ON 
 SEC. 16.19] DELA Y-LINE SIGNAL CIRCUITS 673 originating inthe radar receiver. The high cost ofdelay-line input power makes necessary thecareful conservation ofoutput signal. 
 CENTERED OVALS AT LARGE BASELINE RANGES ARE DICTATED BY OPERATIONS AND COST BOTH COOPERATIVE AND NONCOOPERATIVE TRANSMITTERS 
 Thematched-filter receiver, oranapproximation, has beengenerally preferred inthevastmajority ofapplications. lOADETECTION CRITERIA.J Thedetection ofweaksignalsinthepresence ofnoiseisequivalent todeciding whether the receiver outputisduetonoisealoneortosignal-plus-noise. Thisisthetypeofdecision probably made(subconsciously) byahumanoperator onthebasisoftheinformation present attheradarindicator. 
 R.: Principles and Performance Analysis of Doppler Navigation Systems, IRE Trans.,  vol. ANE-4, pp. 176-196, December, 1957. 
 STATE POWER AMPLIFIER MODULE COMBINES MANY SINGLE STAGE AMPLIFIERS TOGETHER WITH  MATCHED PHASE AND AMPLITUDE USING RESISTIVELY ISOLATING COMBINING TECHNIQUES .   3/,)$ 
 A typical value of loss for a  nonmatched receiver might be about l dB. Because of the exponential relation between the  false-alarm time and the threshold level [Eq. (2.26)], a slight change in the threshold can caus1.:  a significant change in the false alarm time. 
 1.. , Mechanical beam-scanning withplanartwist-reflector. Theantennaconfiguration shownin Fig.7.13maybeemployed to'rapidly scanabeamoverarelatively wideanglebymechanical motionoftheplanarmirror.Thisconfiguration hasbeencalledamirrorscanantenna(bythe NavalResearch Laboratory), polarization twistCassegrain andflatplateCassegrain (by Westinghouse Electric), andaparabolic: reflector withplanarauxiliary mirror(byRussian authors138).Theparabolic reflector isniadeup ofparallelwiresspacedlessthanahalf- 'I' •. 
 Unlike radio waves atfrequencies lower than about 30Me/see, microwaves are not reflected from the ionosphere. This means that the maximum range ofaradar setwhose performance isnot otherwise limited will besetbythe optical horizon which occurs because the earth isround. This isinfact thelimitation onthe performance ofthe best radar Sets developed during the war. 
 A gaussian antenna pattern is assumed in this figure. The  calculated improvement factor for the sequence shown (total clutter power into the  filter divided by total residue power out of the filter, normalized by the noise gain of  the filter) is 58 dB. A sin( x)/x antenna pattern is assumed for the following three figures, but the lessons  to be gained from these figures is essentially independent of the assumed beam shape. 
 TIAL RESOLUTION   BUT IT TAKES MORE TRANSMITTER POWER 3UITABLE FREQUENCY AGILITY CAN  ACCOMPLISH THE SAME RESULT 4RADEOFFS EXIST BETWEEN SPATIAL RESOLUTION AND MEASUREMENT PRECISION 4HE LATTER  CAN BE USED TO DEFINE A  GRAY 
 These assumptions, usually met, amount to assuming that values of the noise voltage separated by the pulse duration are statistically independent; this independence occurs for times separated by 1/Bn, sometimes called the Nyquist interval. Since ordinarily Bn = I/T and tg = T, 1/Bn is sometimes used in place of T or t in the false-alarm-time equations. Marcum's false-alarm number ri is related to the false-alarm probability by the equation DETECTABILITY FACTOR D0 (DECIBELS) . 
 At S band the cross section of a cabbage looper moth is about 2 x 10-l cm2, and  for an adult field cricket it is 0.1 cm2 .103 The cross section of insects bdow X band is  approximately proportional to the fourth-power of the frequency. 104· 1°5 Appreciable echoes  are obtained only when insect body lengths are greater than a third of the radar wavelength.  Insects observed broadside have echoes 10 to 1000 times greater than when viewed  end-on.116  Heavy angel activity can be readily produced by insect concentrations that would scarcely  cause visual awareness. 
 KM WIDE SWATHS WERE COVERED  AT  
 Soc. , vol. 54, pp. 
 The surface descriptors generally used in connection with sea clutter—sea state, wind speed, and its associated equilibrium waveheight—are given in Table 13.1, with the wind speed in knots, the significant waveheight in feet, and the duration/fetch required for a fully de- veloped sea in hours/nautical mile. It is of interest to note that the median wind speed over the world's oceans is about 15 kn, corresponding to sea state 3. TABLE 13.1 Sea-Surface Descriptors 13.3 EMPIRICAL BEHAVIOR OF SEA CLUTTER Sea clutter is a function of many parameters, some of them showing a compli- cated interdependence; so it is not an easy task to establish its detailed behavior with a great deal of confidence or precision. 
  TWO 
 This estimated phase shift is added to the phase shift, which is applied to the  data on the previous sweep, and this new phase shift is applied to the current data. The range averaging must be performed separately on the I and Q components of  the measured phase in each range cell due to the 2 p ambiguity of the phase representa - tion itself. The accumulation of the applied phase shift from sweep to sweep, however,  must be performed directly on the phase and is computed modulo 2 p. 
 TAINING THE EXPECTED SIGNAL SAMPLES IN THE ARRAY FROM A TARGET ALONG A CERTAIN DIRECTION  OF ARRIVAL 4HE SIMILARITY OF %Q  TO %Q  GOVERNING THE 3,# IS IMMEDIATELY RECOGNIZED 7ITH RESPECT TO 3,#  ADAPTIVE ARRAY TECHNIQUES OFFER THE CAPABILITY OF ENHANCING  THE TARGET SIGNAL WHILE CANCELING THE DISTURBANCE 4HE ADAPTIVE SYSTEM ALLOCATES IN AN OPTIMUM FASHION ITS DEGREES OF FREEDOM TO THE ENHANCEMENT OF THE TARGET SIGNAL AND TO THE CANCELLATION OF JAMMER 3EVERAL GENERALIZATIONS OF THE BASIC THEORY HAVE BEEN CONSIDERED  INCLUDING I   THE TARGET MODEL  3 IS NOT KNOWN A PRIORI  AS IT IS ASSUMED IN DERIVING %Q  II  IN  ADDITION TO SPATIAL FILTERING  DOPPLER FILTERING IS PERFORMED TO CANCEL CLUTTER AND CHAFF AND III  THE RADAR PLATFORM IS MOVING AS IN SHIPBORNE  AIRBORNE  OR EVEN SPACEBORNE APPLICATIONS ! RELEVANT ADVANCEMENT OF THE ADAPTIVE ARRAY CONCEPT IS SPACE 
 The surrounding reference cells are then used to estimate the unknown parameters, and a threshold based on the estimated parameters is obtained. The simplest adaptive detector, shown in Fig. 8.12, is the cell- averaging CFAR (constant false-alarm rate) investigated by Finn and Johnson.22 If the noise has a Rayleigh density, p(x) = x exp (-Jt2/2a2)/a2, only the parameter a (a2 is the noise power) needs to be estimated, and the threshold is of the form T = KZxj = £>xVir/2<T, where a is the estimate of a. 
 Streamlining. -There isnosimple foolproof answer tothe aerodynamical problem. Each installation has peculiarities ofitsown, depending upon itslocation ontheairplane inquestion, the plane itself, the speed ofthe plane, and the size and shape ofthe radome. 
 J.: Sequential Methods in Radar Detection, Proc. IEEE, vol. 58, pp. 
 To reduce the number of false alarms when narrow-pulse interfer- ence is present, the individual power ratios can be soft-limited25 to a small enough value so that interference will cause only a few false alarms. A compar- ison of the ratio detector with other commonly used detectors is shown in Figs. 8.15 and 8.16 for nonfluctuating and fluctuating targets. 
 Wetzel, Naval Research Laboratory (CHAPTER 13) Nicholas J. Willis, Technology Service Corporation (CHAPTER 25) . PREFACE This edition has been thoroughly revised to reflect the advances made in radar over the past two decades. 
  AND  6 
 If the VCO has a defined nonlinearity characteristic, the voltage into the integrator can be varied during the pulse so that the voltage ramp compensates for the VCO nonlinearity. Precompensation of this type is often employed. The char- acteristics of several common VCO devices are given in Table 10.3. 
 Both the thickness and the weight may be reduced considerably by stepping or zoning  the lens (Fig. 7. t 811). 
 An example of the shape of a bandwidth-limited  rectangular pulse is shown in Fig. 11.5. The integrals in the expression for P2 [Eq. 
 The low- noise amplifier (LNA) is either a cooled maser or a field effect transistor and may be switched between the  antenna and an ambient load, allowing amplitude calibration of the input. During bistatic operations, a signal  from the low-level noise diode, previously calibrated against the ambient load, may be injected to monitor  real-time performance of the system. Microwave inputs (1–10 GHz) are mixed to a 300 MHz intermediate  frequency (IF) for amplification. 
 AES-5, pp. 632-637, July 1969. 42. 
 The use of multiple simultaneous receive beams will reduce the search frame  time, since many beam positions are searched at the same time. When using multiple  simultaneous receive beams, the transmit beam can be broadened by beam spoiling so  that the 3-dB beamwidth is larger than that of a uniformly illuminated array with a linear  phase front. Broadening the beam on transmit reduces the gain of the transmit beam,  but this loss in gain may be necessary to produce the search frame time required. 
 This is a method for  achieving the equivalent of a multiple-beam array.  There have been at least two different variations of within-pulse scanning which have  314INTRODUCTION TORADAR SYSTEMS Thelowcrossover leveloftheButlerarrayisoneofitsdisadvantages. Ifalosslessnetwork couldbeachieved withacosineillumination soastoreducethesidelobelevelscompared to thoseobtained withauniformillumination, thecrossover levelwouldbeevenworse(alevelof -9.5dB). 
 This law, which has been derived invarious forms byNyquist’ and others, isbased ontheequipartition law ofstatistical mechanics and not onany special assumption astothedetails ofthemechanism responsible fortheobserved fluctuations. B k!- Z r“- FIG.2,3.—Schematic diagram ofanideal receiving system. Other sources ofnoise are tobefound inreceivers—notably shot noise invacuum tubes—which dodepend onaspecial mechanism. 
 SCAN PROBABILITY OF DETECTION  WAS FOU ND TO BE  UNDER A  PARTICULAR SET OF OBSERVATIONS 7HEN THE RADAR OPERATED AT FOUR DIFFERENT WIDELY SEPA 
 modulation cycle. If,however, the modulation frequency isadjusted sothat one cycle corresponds tothetransmission delay time, the differ- ence frequency will always just equal the doppler frequent yand soa large output signal will result. Thus, asthe modulation frequency is varied, output occurs whenever n/f,=2r/c with nany integer and r the distance toatarget. 
 39-44, December. 1965.  71. 
 ch13.indd   19 12/17/07   2:39:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 DUCING VERY HIGH OUTPUT POWER LEVELS WITH ACCEPTABLE GAIN AT THE FREQUENCIES USED IN MOST RADAR APPLICATIONS 4RANSISTORS ARE THREE 
 The supporting structure is known asthe“pedestal,” and theentire assembly istermed the“antenna mount” or“scanner.” 1Airplanes and ships are notoriously unsteady vehicles, whose motions disturb the direction ofaradar beam ofenergy transmitted from them. The compensation forsuch motions iscalled “stabilization.’ ) 9.1. The Antenna Equation.’—Two ofthe salient requirements of most radar sets arethat they beable toreveal distant objects and beable togive accurately the direction ofsuch objects. 
 180-184, February, 1952.  39. Jones, C. 
 Standard-design low-impedance synchros are used. Transmitter and repeater areidentical except fortheinclusion ofamechanical damper onthe shaft ofthe repeater. The maximum speed ofrotation ofthe synchros isabout 400 rpm, restricting a10-speed system to40rpm. 
 TARGET TRACKING PROBLEMS v  )%%% 4RANS  VOL !# 
   AN 3 
        4HESE WEIGHTS HAVE BEEN DERIVED BY ASSUMING THAT THE CANCELERS SHOULD PERFECTLY  CANCEL A LINEAR WAVEFORM  6T    C   AT  SAMPLED AT THE STAGGER RATE  INDEPENDENT OF THE  VALUES OF THE CONSTANT  C OR THE SLOPE  A !S MENTIONED AT THE BEGINNING OF THIS SECTION  A  MULTIPLE 
 £x°ÓÓ  2!$!2 (!.$"//+  4HE DETAILS OF THE CLUTTER SPECTRUM SHOW LITTLE DEPENDENCE ON EITHER THE RADAR FRE 
 3.3.2 Transmitter –receiver (T2R unit) TR. 3191 or TR. 3159 3-5 3.3.3 Receiver unit 3-8 3.3.4 Indicator unit type 162 3-8 3.3.5 Switch unit type 207 3-11 3.3.6 Scanner type 51 3-13 3.3.7 Power unit, type 280 3-14 3.3.8 Setting up and operating the radar 3-14 3.4 ASV Mk. 
 244–254,  Algorithms for Synthetic Aperture Radar Imagery, D. A. Giglio (ed.), 1994. 
 If the diode is housed in a package, the parasitic elements introduced by the  package degrade the switching action and influence the voltage breakdown and thermal  characteristics.  The variable capacitance senliconductor element, or rlaracror diode, also can be used as  the switch in a diode phase shifter. It is capable of very rapid switching, of the order of a  nanosecond, but can handle only low power. 
 5.6, except that the sampling gates described here are  of infinitesimal width whereas they are usually of the order of a pulse width in range tracking.  Substituting the optimum gating signal into the expression for accuracy gives (Ref. 3,  Eq. 
 TION  CAN BE ESTABLISHED WITH SUFFICIENT ACCURACY   7HEN TAKING SEQUENTIAL DOPPLER MEASUREMENTS  THE TARGETS VELOCITY VECTOR REMAINS CONSTANT  OR PREDICTABLE &OR  EXAMPLE  MANY DOPPLER 
 NATES THE HYPERBOLOIDAL SUBREFLECTOR  WHICH IN TURN ILLUMINATES THE PARABOLOIDAL MAIN REFLECTOR 4HE FEED IS PLACED AT ONE FOCUS OF THE HYPERBOLOID  AND THE PARABOLOID FOCUS IS COINCIDENT WITH THE SECOND FOCUS OF THE HYPERBOLOID 4HE USE OF A SUBREFLECTOR ALSO ALLOWS THE FEED TO BE LOCATED BEHIND THE MAIN REFLECTOR AND CLOSER TO THE TRANSMITTER AND RECEIVER IN ORDER TO MINIMIZE TRANSMISSION LINE LOSSES &URTHERMORE  IF THE FEED IS LOCATED BEHIND THE MAIN REFLECTOR  THE CENTER OF GRAVITY WILL BE BIASED CLOSER TO THE MAIN REFLECTOR VERTEX THEREBY SIMPLIFYING THE DESIGN OF BOTH THE STRUCTURE AND THE GIMBAL  PRECISION MECHANICAL POSITIONING SYSTEM  4HE 'REGORIAN DUAL REFLECTOR ANTENNA SYSTEM NOT SHOWN IN &IGURE   IS SIMILAR  TO THE #ASSEGRAIN  BUT IT USES AN ELLIPSOIDAL SUBREFLECTOR IN LIEU OF A HYPERBOLOID RESULT 
 O’Sullivan, “A comparison of sidelobe blanking systems, IEE Int. Conf. Radar–87 , Conf. 
 BASED WAVEFORM WITH  MS RADIAL VELOCITY  #OURTESY OF %DWIN -  7ATERSCHOOT  ,OCKHEED -ARTIN -ARITIME AND 3ENSOR 3YSTEMS  3YRACUSE  .9           
 7, pp. 41--46,  September, 1964.  llO. 
 Hammer, I. W.: Frequency-Scanned Arrays, chap. 13 of Skolnik, M. 
 Rollistheside-to-side angularmotionaroundthelongitudinal (fore-and-aft) axisoftheshipor aircraft. Pitchisthealternating motionoftheforeandaft(bowandstern)partsofthevehicle. Yawisthemotionoftheplatform aroundtheverticalaxis. 
 The tilted beam provided a second set of detections to the radar operator as the antenna rotated. The azimuth sep- aration of the center of the two sets of detections corresponding to a single target, correlated by the operator using range, was directly proportional to the height of the target, to within flat-earth and normal propogation approximations. The con- cept of the V-beam radar is illustrated in Fig. 
 Here the device is called the boxcar grtterr~ror.8 The boxcar  generator was also mentioned in the discussion of the MTI receiver using range-gated  filters (Sec. 4.4). ln essence, it clamps or stretches the video pulses of Fig. 
 pp. 323-331. May, 1966. 
 SPHERICAL SEARCH WITH AUTOMATIC TARGET SELECTION AND HANDOVER TO TRACKING )T MAY EVEN ACT AS A COMMUNICATION SYSTEM  DIRECTING HIGH 
 7.1.—Schematic diagram ofchart moves; when this hasbeen accom-projector. plished the direction and speed ofthe ship, aswell asitsinstantaneous position, areknown. Few such chart-projection devices have been built. 
 Main Step Operation Complexity SI: Achieving two sub-view images FFT 10 Nalog2Na SII: Estimating ˆedr(fdc) (Loperations of sliding windowing manipulation, window width: Nw)STFT 10 LN wlog2Nw Complex conjugate multiplication 7 LN w IFFT 5 LN alog2Na Modulus 9 LN a SIII: Estimating the ﬁtting coefﬁcients ofˆedr(fdc)Curve ﬁtting 16 L Scom: Total10Nalog2Na+ (10Nwlog2Nw+7Nw+5Nalog2Na+9Na+16)L Assuming that the number of iterations Kis three, the window width Nwin the IMAM method and the EMAM method is 100, and the number of sliding windowing manipulations LisNa/50, then the complexity of the different methods can be compared as shown in Figure 8. It can be clearly seen that the complexity of the EMAM method is larger than the basic method and the IMAM method due to further estimating and compensating the ﬁrst-order component of the spatially-dependent derivative of the Doppler rate, which increases the data processing time. When Nais 4096, the complexities of the basic method, the IMAM method, and the EMAM method are 9.437 ×106, 7.196×107, and 59. 
 ShapedbeamsandSTC.t\radarthatcandetecta 1 m2targetat200nmicandetecta10-4m2 targetat20nmibecauseoftheinversefourthpowervariation ofsignalstrength withrange. Therefore, smallncarby targctssuchasbirdsandinsectscancluttertheoutputofaradar.To avoidthis,thcreceivcr gaincanbcreduced atshortrangeandincreased duringtheperiod bctwecn pulsessothatthcreceived signalfromatargetofconstant crosssectionremains unchanged withrange.Theprogrammed controlofthereceiver gaintomaintain aconstant echosignalstrength iscallcdsl'lIsitil';ty t;1IIecolltro[(STC).Itisaneffective method for eliminating radarechoesduetounwanted birdsandinsects. STCmakesuseoftheinversefourthpowervariation ofsignalstrength withrange.The cosecant-squared shaping oftheantenna alsoutilizestheinversefourthpowervariation with range(Sec.2.11).Thus,whenSTCisusedwithacosecant-squared antenna pattern, the high-angle coverage oftheradarisreduced. 
 16.46  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Programs to learn microwave properties of sea ice have been numerous because  of the importance of arctic operations and meteorology. Microwave remote sensing  is necessary to monitor ice properties in the arctic owing to the long winter night,  frequent cloud cover, and inaccessibility. 16.8  POLARIMETRY Several synthetic-aperture imaging radars are capable of measuring the full com - plex polarization matrix. 
 D. C. Cross, D. 
 NOISE RATIO FROM A SINGLE  CLUTTER PATCH WITH INCREMENTAL AREA D! AT A RANGE 2 IS   #.0'' D ! 2,K 4"42 #SN AVLS P      WHERE  0AV   AVERAGE TRANSMIT POWER  '4    TRANSMIT GAIN IN PATCH DIRECTION  '2    RECEIVE GAIN IN PATCH DIRECTION  K    OPERATING WAVELENGTH  R      CLUTTER BACKSCATTER COEFFICIENT  ,#    LOSSES APPLICABLE TO CLUTTER  K    "OLTZMANNS CONSTANT    r  
 Res. , vol. 85, pp. 
 Surface-Wave Pulse Compression. A SAW pulse compression unit consists of an input transducer and an output transducer mounted on a piezoelectric substrate. These transducers are usually implemented as interdigital devices which consist of a metal film deposited on the surface of the acoustic medium. 
 M RESOLU 
 Rearranging terms, forcompactness, S=P=.(47r)3R4(3b). 22 THERADAR EQUATION [SEC. 25 Again wecall attention tothefact that Eq. 
 Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar.  SYNTHETIC APERTURE RADAR  17 .236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 Moving Targets in a SAR Image. Displacement of a Moving Target. 
 For· purposes of the present discussion,  however, the exact origin of the extra noise components is not important except to know that  it exists. No matter whether the noise is generated by a thermal mechanism or by some other  mechanism, the total noise al the output of the receiver may be considered to be equal to the  thermal-noise power obtained from an "ideal" receiver multiplied by a factor called the noise  figure. The noise figure F 11 of a receiver is defined by the equation  F n NO noise out of practical receiver --~--= ------------------k T0 B11 Ga noise out of ideal receiver at std temp T0 (2.4a)  where NO noise output from receiver, and Ga = available gain. 
 Thus, theonly gaskets that might affect alignment arethose beneath theend cells. Airisremoved from the line; thermal expansion isaccommodated byabellows within thecylindrical housing ontheside oftheline. Apositive pressure ismaintained sothat any leakage isoutward. 
 LAR AMBIGUITY FUNCTIONS AND DOPPLER SHIFT CHARACTERISTICS 4HE AUTOCORRELATION FUNCTIONS ARE SIMILAR  WITH A PEAK TO SIDELOBE RATIO OF ABOUT  . &RANK #ODES 4HE &RANK CODE CORRESPONDS TO A STEPPED 
 This would appear to be  the ideal navigation system, needing no co-operation  from the ground, and being controlled entirely by the  pilot.or navigator, so necessitating no interpretation of  instructions. It seems unlikely at present that H2S-  type systems will offer great scope for civil aviation,  owing to cost and weight of equipment, but for special  tasks H2S may be the only solution. For radar carto-  graphy, for instance, H2S is an accurate check. 
 Conf ., vol. 15, October 1959. 38. 
 The AIS transceiver does not have to be situated on the actual mark and  could be shore-based to ease maintenance. Used in this way, they are known as Virtual  AIS AtoNs.29 Up-to-date information concerning the mark and its integrity can be  automatically or manually fed-in by port authorities. Such systems can also be used  for alerting mariners of the position of recent wrecks and other temporary and perhaps  visually unmarked navigation hazards. 
 *-Ê, ,Ê-9-/ 
 Radar Conf. Publ. 281, pp. 
 Óx°Ó{  2!$!2 (!.$"//+  4HE COSP I  COLUMN SHOWS THE COSINE OF THIS ANGLE  WHICH SHOULD BE MULTIPLIED BY  THE RESULT OF EACH ITERATION  AS SHOWN IN THE EQUATIONS ABOVE )N ACTUAL APPLICATIONS   HOWEVER  THIS COSINE MULTIPLICATION IS NOT PERFORMED AT EVERY ITERATION !T EACH STAGE  THE IMPLIED FACTOR THAT NEEDS TO BE MULTIPLIED BY THE )1 OUTPUTS OF THE STAGE IN ORDER TO PROVIDE THE CORRECT ANSWER IS THE PRODUCT OF ALL OF THE COSINES UP TO THAT POINT  AS SHOWN IN THE 0;COSP  I = COLUMN &OR A LARGE NUMBER OF ITERATIONS  THIS PRODUCT OF COSINES  CONVERGES TO A VALUE OF  )N MOST CASES  THIS SCALING CAN BE COMPEN 
 RITHMS SUCH AS MODERN SPECTRAL PROCESSING AND ADAPTIVE FILTERING TO BE IMPLEMENTED  £°xÊ "* 
 Takimoto, M. Kotaki, Automotive AnticollisionRadar, Applied Microwave , Fall  1992  13.3.12  Exercises for ACC Radar   Given specification:     € R=100m F=75GHz σ=1m2 ΔR=1,5m Δx=1,75m Δy=1,75m Runamb =1000m S/n=14dB NF=10dB LRF=12dB    Check whether all the required specifications are present.  Expand the specification if nece s- sary by assigning meaningful and appropriate values. 
 PULSE OR DWELL 
 This results instanding waves intheline. These can beobserved bysliding asmall probe along aslot intheline after themanner shown foraconcentric line inFig. 11.1. 
 LATE THE ACTUAL AMPLITUDE RESPONSE OF REAL TARGETS AND  HENCE  ARE MORE EFFECTIVE OVER TRANSPONDER 
  D"  OR LOW  
 one on the  intermittent pulsed signal which will show like a beacon  on the radar display of searching craft.  Among the numerous track guides and instrument —  approach systems predominant is Babs, the beam- -  approach beacon system. It enables aircraft to be  brought to the boundary of an airfield with precision,  - and with most types comes into operation first when the  navigator is about 20 miles away from the field. 
 Almost all radars have a receiver which closely approximates the matched filter. The second detector in the receiver is an envelope detector which eliminates the IF carrier and passes the modulation envelope. When doppler processing is employed, as it is in CW (continuous-wave), MTI, and pulse doppler radars, the envelope detector is replaced by a phase detector which extracts the doppler fre- quency by comparison with a reference signal at the transmitted frequency. 
 24.8. Each of these soundings was made at the same hour but on a different day of the month. In this figure each trace shows the virtual height of a vertical sounding versus probing frequency for the ordinary ray. 
 For linearly polarized radar applications, aperture  blocking can be significantly reduced by using a polarization-twist reflector and a  subreflector made of parallel wires.24 This twist reflector design enables a 90° rotation  of the polarization such that the polarization of the beam upon reflection from the main  reflector is orthogonal and transparent to the gridded subreflector . Blockage can also be eliminated by offsetting both the feed and the subreflector  (Figure 12.23 c). With blockage and supporting struts and spillover virtually elimi - nated, this geometry is useful for very low sidelobe applications.24 As described earlier, the aperture efficiency of single reflector systems is maxi - mized by balancing the feed taper and the feed spillover and minimizing other losses,  but is typically 55–65%. 
 DOPPLER RESPONSE OF  
 Section 2presents an introduction of the theory for CNNs, transfer learning and components of our method. The details of the experiments are described in Section 3, we also present our discussion in this section. Finally, Section 4offers the conclusion. 
 The size of the images were 256 ×256 for this test. The change maps of the methods can be seen in Figure 8. The results of the quantitative metrics are given in Table 2. 
 The radar system and orbit parameters are shown in Table 2. The contrast simulation on stripmap mode SAR system also follows the parameters in Table 2. The simulations are performed by using the ReBP–based SAR–SS which is shown in Figure 9and the detailed process is described as follow: The SLC image is used as the input and the image scene is deﬁned in the earth-centered earth-ﬁxed (ECEF) coordinate. 
 M., and D. L. Moffatt: Transient and Impulse Response Approximations, Proc. 
 Limitations. In spite of their wide capabilities, magnetrons may not be suitable for various reasons: . 1. 
 21. Craig, C. W. 
 V . Trunk7) ch07.indd   38 12/17/07   2:14:39 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 STATE&)'52%   #OMPARISON OF -4) IMPROVEMENT FACTOR OF BINOMIAL 
 SURVEILLANCE RADAR v  )%%% 4RANS  VOL !%3 
 TO 
 An example of such a bipolar  video (either I or Q), received from a single transmitted pulse and including both clut - ter and point targets is sketched in Figure 2.4. If the point targets are moving, the super - imposed bipolar video from several transmitted pulses would appear as in Figure 2.5. The remainder of the block diagram in Figure 2.3 shows the remaining process - ing required so that the moving targets can be displayed on a PPI or sent to an auto - matic target extractor. 
 This is usually a radar on a missile that allows the missile to  “home in,” or guide itself, to a target. Weather (meteorological) observation . Such radars detect, recognize, and measure  precipitation rate, wind speed and direction, and observe other weather effects  * Coherent  implies that the phase of the radar signal is used as an important part of the radar process. 
 Both the sampling  and quantization process produce errors that must be minimized in order to limit the  radar performance degradation. In addition, a variety of other errors such as additive  noise, sampling jitter, and deviation from the ideal quantization, result in non-ideal  A/D conversion. Applications. 
 [ CrossRef ] 15. Meyer, F.J. Performance Requirements for Ionospheric Correction of Low-Frequency SAR Data. 
 TO 
 SinceBgmustbegreaterthanorequaltoBntoavoidgratinglobes,thefollowing condition isobtained 2vv fp?-D=~ Ocr(\4.8) Theright-hand portionoftheequation appliesforafocusedSAR,sinceber=D/2. Combining therestriction onprfduetounambiguolls rangeRuwiththatofEg.(14.8) yields (14.9). This leads to the condition  Tllrrs tlic rrnanibigi~or~s rilligc arid tile resolution cannot be selected independently of one  ariotlier. 
 02& AND CAN BE CONSIDERED  TO BE IN THE HIGH 
 This assumption of a linear system may be unrealistic for some practical MTI systems with relatively few hits per beamwidth, as discussed in Sec. 15.10. The scanning limitation does not apply to a system that can step-scan, such as a phased array. 
  n 4OTAL INTEGRATED NOISE POWER E 
   -ARCH   7 7ASYLKIWSKYJ AND 7 + +AHN  h%LEMENT PATTERN BOUNDS IN UNIFORM PHASED ARRAYSv  )%%%  4RANS  VOL !0 
 By assuming that the target is small with respect to the pulse width and that the pulse shape is known, the resolution capability can be improved by fitting . TABLE 8.2 Probability of Detecting with Log Video Two Targets Separated by 1.5, 2.0, 2.5, or 3.0 Range Cells* *S/N of target 1 is 20 dB. S/N of target 2 is 10, 13, 20, 30, or 40 dB. 
 121. pp. 1460-1466, December, 1974. 
 The target RCS is labeled “size” and is  treated as constant. ch20.indd   63 12/20/07   1:17:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 In a high- PRF radar, there is little if any range region clear of sidelobe clutter, such that the sidelobe clutter portion of the doppler spectrum is often not processed (since target detectability is severely degraded in this region). Further, in a high-PRF radar, especially at higher altitudes, the relative amplitudes of the distributed sidelobe clutter and the discrete returns are such that the discretes are not visible in the sidelobe clutter. The apparent radar cross section (RCS), crapp, of a sidelobe discrete with an RCS of cr is aapp = a GSL2, where GSL is the sidelobe gain relative to the main beam. 
 G. Ingerson, and W. C. 
 The SCR-584 Radar, Electronics, pt. 1, vol. 18, pp. 
 This scattering problem relies on  the same two equations, but instead of measuring the total fields over a closed surface  surrounding the body, one determines the fields induced on the body surfaces them - selves by the incident wave and then solves a system of linear equations. These surface  fields become unknowns to be determined. The two equations are coupled because the  unknowns appear on both sides of both equations. 
 Inoneimplcmcntation, aninterferometer wasattached totherotating antenna ofa2D S-handair-surveillance radar.42The20radarprovided therangeandazimuth aswellasthc transmilled cnergyforthereceiving interferometer. Theinterferometer consisted offourlinear horizontally oriented arrays.orsticks,withonestickmounted belowthe2Dradarantenna andtheotherthreesticksmounted above. Theelevation beamwidths ofeachoftheindividual antennas oftheinterferometer are generally broadsothatmultipath duetoground reOections cancauseerrors.Shaping the underside orthe2Dtransmitting anlenna tominimize theenergyilluminating thesurfacecan. 
 Snow.  When snow covers the ground, much of the scatter is from the snow  rather than the underlying ground. Snow is both a volume-scattering and an attenuat - ing medium. 
 These are sometimes called cleaned-up displays since the noise and background clutter are removed. Radar Control. A modern radar can operate at different frequencies within its band, with different waveforms and different signal processing, and with dif- ferent polarizations so as to maximize its performance under different environ- . 
 HORIZON SEPARATION 7HILE MANY ORDERS OF MAGNITUDE ATTENUATION ARE POSSIBLE WITH THESE MASKING AND SHIELDING TECHNIQUES  ADDI 
 NOISE RATIOS 4HE EXPECTED PERFORMANCE OF A PARTICULAR RADAR DESIGN CAN BE EXPLORED WITH THESE GRAPHS BECAUSE SUMMER AND WINTER DO GIVE GOOD COVERAGE OF THE IMPORTANT VARIABLES 4HE PERFOR 
 Spetner, “Polarization and depression angle dependence of radar terrain return,”  J. Res. Nat. 
 This spectral spread prevents perfect cancellation of clutter in the MTI system. FIG. 15.9 Pulse transmitter spectrum. 
 O. Carhoun, J. D. 
 (After Daley, et al.3) ._;) . RADAR CLUTTER 477  which such measuremen ls can be made. The solid curves of Fig. 
 Geosci. Remote Sens. 2014 ,62, 4664–4673. 
 FORMS DEFINED OVER TWO OR MORE SEPARATE SUBBANDS ARE READILY SYNTHESIZED -OST EARLY (& SKYWAVE RADARS EMPLOYED PULSE WAVEFORMS  IN PART  BECAUSE THE TECH 
 K. Mains: Detection and Discrimination of Radar Targets, lEEE Trans, vol  AP-23, pp. 358-367, May, 1975. 
 IRE ,  vol. 21, pp. 420–433, May 1961. 
 FORMS v )%%% 4RANS  VOL !%3 
 Vertical Beam Width Small surface targets may escape the lower edge of the vertical beam when close. FACTORS AFFECTING RANGE ACCURACY The range accuracy of radar depends upon the exactness with which the time interval between the instants of transmitting a pulse and receiving theecho can be measured. Fixed Error A fixed range error is caused by the starting of the sweep on the indicator before the r-f energy leaves the antenna. 
 Main channel detections are examined for  GMTs and centroided in range and doppler (because a return in range or doppler may  straddle multiple bins, the centroid of those returns in multiple bins must be estimated  from the amplitude in each bin and the number of bins straddled). The guard channel  is detected and the thresholded results are used to gate the main channel results for the  final hit-miss count. Genuine targets are resolved in range and doppler, presented to a  display and used for TWS correlation and tracking.8 False alarms are a critical issue in most radar modes. 
 OF 
 ANGLE MULTIPATH REGION AND THE AVAILABIL 
 3RLReport No.809, Sept. 28,1945.. SEC.109] THEHARD-TUBE PULSEh? 367 Figure 10.28 shows how differing internal impedances can affect mode stability: operation intheunwanted %mode isimpossible inthecase ofa pulser load line such asB,but may occur iftheload line has theform of AorC. 
 A. Campbell, L. M. 
 TO 
 P.: Adaptive Arrays, IEEE Trans., vol. AP-24, pp. 585-598, September 1976. 
 DOMAIN SIGNATURES THE REFLECTIONS WILL MERGE TOGETHER !S THE ANTENNAS GENERALLY USED FOR '02 HAVE POOR DIRECTIVITY  THE PATTERN OF THE  REFLECTED WAVEFORM IN THE " 
 Hanle, E.: Pulse Chasing with Bistatic Radar-Combined Space-Time Filtering, in Schussler, H. W. (ed.): "Signal Processing II: Theories and Applications," Elsevier Science Publishers B.V., North Holland, pp. 
 Moore, “SOURCESCAT: A very fine resolution radar scatterom - eter,” Microwave J. , vol. 28, pp. 
 2X AVG    WHERE %   COLLECTED ENERGY  K   "OLTZMANNS CONSTANT     ¾ n JOULE+ELVIN  4   STANDARD TEMPERATURE  +   &   hNOISE FIGURE v WHICH IS TYPICALLY ABOUT    02X AVG 
 6165–6168. 15. Lu, X.; Yuan, Y.; Zheng, X. 
 Thk iscommon inthe 10-cm region. The large 1~-in. OD line and the doorknob transitions just mentioned are used. 
 tlic sl~ectrunl itrid target rcsolutio~l approach that oblai~led wit11 a pulsc or all ITM-C'W  waveform.  -I'l~c ~licirstrreillcrlt of range by ~neasuring tlic phase difference between separated frequeri-  cies is analogous to tlie measurement of angle by measuring the phase diflerence betwee11  widely spaced antennas, as in an interferometer antenna. The interferometer antenna gives an  accurate but ambiguous measurement of angle. 
 Battan, W. G. Harper, B. 
 Furthermore, the operator  is probably better able to recognize and interpret patterns relating groups of associated echoes  than can automatic devices.4 7  It has been shown experimentally that when an operator views a display in which the  pulses received from successive sweeps are displayed side-by.side without loss of memory  (fading of the recorded signals with time), the integration improvement achieved by an opera­ tor is equivalent to what would be expected from classical detection theory.48·49 This is  illustrated by the data of Fig. 10.6, which plots the experimentally observed signal-to-noise  ratio necessary to achieve a probability of detection of 0.50 as a function of the number of  pulses available on the display. Curve A applies to a chemical recorder which makes a  permanent record, and curve B applies to an intensity modulated B·scope of long persistence. 
 For example, the filter may delay the  starting frequency of the LFM more than the ending frequency  of the LFM, causing the leading edge of the pulse to be  delayed more tha n the trailing edge .  When the  pulse passes  through a receiver signal processor, the chirp will transform  from a frequency chirp pulse to a narrow pulse containing all  the frequencies overlapped. The width of the resulting pulse is  dependent on the frequency resolution of the receiver  processor. 
 SCAN II  /NE IS A LIMITED ANGLE SCAN AS IN SOME  AIR 
 I'his is a good conipro~nise frequency for a long-range air-surveillance radar.  iliglicr frcque~lcies can provide tlic sitme angular bearnwidths with smaller antennas, but the  snlallcr apertures ~ilust be co~npc~isnted by greater power if tlie maximum ranges are the same.  Alrllol~pl~ Iiigh-power transtilitters are available at S band, the peak power that can he  rraris~iiitted is less because of the s~naller waveguide sizes. 
 CENTERED AT  
 Thus, at 40 hits per beamwidth, these two  zeros are too far removed from the origin to be very effective.) FIGURE 2.37  Improvement factor limitation due to scanning for cancelers with feedback ch02.indd   38 12/20/07   1:44:39 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 Hybrid junctions can also be used. These  produce a 180" phase difference between the two output signals and require a slightly different  design procedure. loo  It is of interest to note the relation of the Butler network to the Fast Fourier Transform  (FFT). 
 FEEDBACK RMS RESPONSE  FOR THREE SCANS AT A TARGET VELOCITY OF  6 "  WOULD BE  
 " 1 /",- !PPLICATIONS 4HE )1 DEMODULATOR  ALSO REFERRED TO AS A QUADRATURE CHANNEL  RECEIVER  QUADRATURE DETECTOR  SYNCHRONOUS DETECTOR  OR COHERENT DETECTOR  PERFORMS FRE 
 DIGITAL CONVERTER !$#  4HE SAMPLES  STORED IN MEMORY  CAN BE MANIPULATED IN AMPLITUDE  FREQUENCY  AND PHASE TO GENERATE A WIDE RANGE OF JAMMING SIGNALS 4HE STORED SAMPLES ARE LATER RECALLED  PROCESSED BY THE DIGITAL 
 5.The conveying ofsine and cosine bya-fsignals ofdifferent fre- quencies. Certain qualitative comparisons among these arepossible. The method ofrelaying angular increments bymodulator-pulse timing isbyfarthe simplest ifitcan beused, which isonly when the scanner rotates very uniformly and can beexactly synchronized with the modu- lator. 
 TER REJECTION WITH SHORT DWELLS  &ACT  4RANSMITTER INTRAPULSE ANOMALIES HAVE NO AFFECT ON -4) PERFORMANCE IF  THEY REPEAT PRECISELY PULSE TO PULSE 4RANSMITTED PULSES SHOULD BE IDENTICAL )T DOES NOT MATTER IF THERE IS INTRAPULSE AMPLITUDE OR FREQUENCY MODULATION OF THE TRANSMITTED  PULSE  AS LONG AS IT REPEATS PRECISELY FROM PULSE TO PULSE )F THE VOLTAGE OF THE TRANS 
 Figure 8. Estimated model parameters: ( a)elasticity ,E;(b)viscocity ,η;(c): linear velocity, v; and ( d) height correction, ΔZ. Figure 9shows the overall time-series deformation results obtained for the test highway. 
 Image Process. 2010 ,19, 141–153. 9. 
 69. Kroszczynski, J.: Efficiency of Attenuation of moving Clutter. Tlre Rudio utrd Elrctrotric Enyr.. 
 Thetworeceived signalsaremixedinanonlinear deviceandthedifference frequency isextracted fornormal MTIsignalprocessing. Theadvantage ofthegreaterfirstblindspeedobtained withthetwo-frequency MTI is accompanied byseveraldisadvantages.73Iftheratioofthetwofrequencies is,.<1,the standard deviation oftheclutterdopplerspectrum a,forasingle-frequency MTIisincreased tofT<(1I-,.2)''2inatwo-frequency MTI.(Thisassumes thattheclutter-velocity spectrum width fT,.isthesameforbothcarriers. orat=/'(}2wherea,anda2aretheclutterdoppler­ frequency spreads. 
 Trunk et al., “False alarm control using doppler estimation,” IEEE Trans. Aerospace and  Electronic Systems , vol. AES-26, pp. 
 D" 4AYLOR WEIGHTING 4HESE RESULTS ASSUME THAT THE TIME 
 (2.57). This must be  modified for an HF radar since the coherent integration tim'e T, is fixed in an HF radar by the  doppler processing requirements. Also in an HF radar, the elevation beamwidth 0, is often not  available as a design parameter because of the large cost ofhigh antenna structures. 
 Óä°£ä  2!$!2 (!.$"//+  (ENCE  TO ACHIEVE  ,    KM AT  KM RANGE WHEN THE FREQUENCY IS  -(Z  AND  THUS A RESOLUTION CELL NOT TOO ECCENTRIC IN SHAPE  REQUIRES AN ARRAY APERTURE OF ABOUT   M &EEDING ARRAYS OF THIS SIZE CAN REQUIRE HUNDREDS OF KILOMETERS OF CABLES OR  IN SOME SYSTEMS  FIBER OPTICS  AND RAISES CHALLENGING PROBLEMS IN ARRAY CALIBRATION 4HE TRANSMITTING ARRAY APERTURE  ASSUMING  y  RECEIVE BEAMS TO BE FITTED INTO THE TRANSMIT  BEAM  NEED BE ONLY ^  M AT THIS FREQUENCY )T FOLLOWS FROM THE RADAR EQUATION AND THE CONSIDERATIONS JUST  DISCUSSED THAT TRANS 
 CAVITY 474 CAN BE  TO  4HE RING 
 III, a slant to plan range converter was provided in the form of curves on a drum on the switch unit. Once the height had been set, the range pointer on the drum indicated the plan range. Thisfeature was removed on ASV Mk. 
 Candes, E.; Tao, T. The Dantzig selector: Statistical estimation when p is much larger than n. Ann. 
 90. J. F. 
 TEXT BOOK:    1. Introduction to Radar Systems – Merrill I. Skolnik, TMH Special India n Edition, 2nd Edition,       Tata McGraw -Hill, 2007. 
 V . Hitney, “Refractive effects from VHF to EHF, part B: propagation models,” Advisory Group  for Aerospace Research & Development, AGARD-LS-196, pp. 4A1–4A13, September 1994. 
 Clarke, and R. S. Peters: Weibull Distribution Applies to Sea Clutter, lnter11acio11al  Co,!ference RADAR-77, pp. 
 All of these are well described in standard texts on optics and  electromagnetic theory. In summary, these descriptions allow the state of an electro - magnetic wave to be described in terms of linear, elliptical, and circular polarization  (left-handed or right-handed). It is well known that linear targets such as wires act  as depolarizing features and that a linearly polarized crossed dipole antenna rotated  about an axis normal to a linear target such as a wire or pipe produces a sinusoidal  variation in received signal. 
 AES–29, no. 2, pp. 725–735, April 2003. 
 The received levels are kept below saturation levels, typically with a clutter AGC in search and a target AGC in single-target track, to prevent spurious signals, which degrade per- formance, from being generated. Clutter Positioning. A voltage-controlled oscillator (VCO), usually part of the stable local oscillator (stalo), is used to heterodyne main-beam clutter to zero frequency, or dc. 
 Free-space Propagation.  The simplest case of electromagnetic wave propaga - tion is the transmission of a wave between a transmitter and a receiver in free space.  Free space is defined as a region whose properties are isotropic, homogeneous, and  loss-free, i.e., away from the influences of the Earth’s atmosphere and surface. 
 RESOLUTION  BACKSCATTER FROM THE SEA v 2ADIO 3CI  VOL   PP n    * 0 (ANSEN AND 6 & #AVALERI  h(IGH RESOLUTION RADAR SEA SCATTER  EXPERIMENTAL OBSERVATIONS AND  DISCRIMINANTS v .AVAL 2ESEARCH ,ABORATORY 2EPORT .O   . 
  +NOWN ALTERNATIVELY AS 2EMOTE 3ENSING 3ATELLITE 
 We can increase our accuracy, first of all, by realizing  that the exact distance between the two blips (marking  the transmitted-pulse instant and the echo-return  instant) is the distance between the leading edges of the  two V-shaped blips. We must not cause confusion by  measuring between, say, one leading edge and one  lagging edge. We must take our measurements from the  . 
 Letting  P* = S(f) exp (jZnfl,) and Q = H(f)  and recalling that  372INTRODUCTION TORADAR SYSTEMS Wewishtoshowthatthefrequency-response function ofthelinear,time-invariant filter whichmaximizes theoutputpeak-signal-to-mean-noise ratiois H(J)=GaS*(J) exp(-j2nft1) whentheinputnoiseisstationary andwhite(uniform spectraldensity). Theratiowewishto.. .maxImIze IS (to.7) wherejso(t)lmax =maximum valueofoutputsignalvoltageandN=meannoisepowerat receiveroutput.TheratioRfisnotquitethesameasthesignal-to-noise ratiowhichhasbeen considered previously intheradarequation. 
 Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 14.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 Frequency, GHz RCS, m2 0.41 0.033–2.33 1.12 0.098–0.997 2.89 0.140–1.05 4.80 0.368–1.88 9.375 0.495–1.22TABLE 14.3  Measured RCS of a Man16Insect Length, mm Width, mmBroadside  RCS, dBsmEnd-on   RCS, dBsm Blue-winged locust 20   4 −30 −40 Armyworm moth 14   4 −39 −49 Alfalfa caterpillar butterfly 14 1.5 −42 −57 Honeybee worker 13   6 −40 −45 California harvester ant 13   6 −54 −57 Range crane fly 13   1 −45 −57 Green bottle fly  9   3 −46 −50 Twelve-spotted cucumber beetle  8   4 −49 −53 Convergent lady beetle  5   3 −57 −60 Spider (unidentified)  5 3.5 −50 −52 NOTE:   Original values reported in square centimeters have been converted here to dBsm, which is decibels  relative to a square meter.TABLE 14.2  Measured Insect RCS at 9.4 GHz15 FIGURE 14.10  Sample of measured RCS of insects  as a function of insect mass at 9.4 GHz, based on Riley’s  summary. The dashed line is the calculated RCS of water  droplets for comparison. 
 Thisisamethodfor achieving theequivalent ofamultiple-beam array. Therehavebeenatleasttwodifferent variations ofwithin-pulse scanning whichhave. TIlE t:l.l:('7'RONI('AI.I.Y STEERED PIIASED ARRAY ANTENNA IN RADAR 315  been demonstrated experimentally. 
 This data was also  obtained from an aircraft in flight. (The T-38 is a twin-jet trainer with a 7.7 m wing span and a  14 m length.) . Ll .. 
 But if the second set of pulses  (Fig. 19), usually Known as the ‘gating’ pulses, are  G  . 98 HOW RADAR WORKS  applied to the suppressor they may be arranged to be of  sufficient potential at peak to permit an anode current  flow for the duration of each gating pulse. 
 RESOLUTION  CLOUD MEASUREMENTS WITH HIGH SENSITIVITY IS ONE OF THE TECHNICAL GOALS FOR ACQUIRING NEW INFORMATION REGARDING CLOUD EFFECT ON THE %ARTHS CLIMATE #LEAR 
 J.M .. and M. I. 
 BEAM CUR 
 310-317.  105. Bachman, C. 
 Cooper et al. [ 16] used the inertial instability model and the Environmental Research Institute of Michigan (ERIM) Ocean Model to simulate SAR images of ﬁlm-generated eddies and analyzed the effects of radar parameters and wind ﬁelds on eddy imaging. However, SAR image simulation for shear-wave-generated eddies has rarely been performed, and the inﬂuence of different radar parameters and wind ﬁeld conditions on imaging characteristics of these eddies has not been discussed systematically. 
 Although the bright band is relatively thin,  considerable attenuation can occur'when radar observations are made through it at low  elevations.  The bright band is due to changes in snow falling through the freezing level.7L At the  onset of melting the snow changes from flat or needle-shaped particles which scatter fcehly to  similarly shaped particles which, owing to a water coating, scatter relatively strongly. As  melting progresses, the particles lose their extreme shapes, and their velocity of fall increases  causing a decrease in the number of particles per unit volume and a reduction In the  backscatter. 
 Actually, if any other model is developed for the topside proﬁle, the proposed TEC modiﬁcation strategy could also be taken as an auxiliary process. One should note that the proposed method could only detect the TEC under the altitude of the satellite. However, it is still reliable to expand the modiﬁed ionosonde proﬁle beyond this altitude, since TECs under 700 km cover the majority of TECs under 10,000 km. 
 or reflectivity, is defined as  (TC  If= 1 ·  ( (IJ.2)  where l'Tc in this case is the radar cross section from the volume V,..  IJ.2 SURFACE-CLUTl'ER RADAR EQUATIONS  Consider the geometry of Fig. 13.1 which depicts a radar illuminating the surface at a grazing  angle </>. 
 Any use is subject to the Terms of Use as given at the website. Reflector Antennas.  REFLECTOR ANTENNAS  12.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 12.5 REFLECTOR ANTENNA ANALYSIS Reflector antenna analysis methods can generally be lumped into three classes or catego - ries: (1) Physical Optics (PO), or induced current methods, (2) Geometrical Optics (GO)  methods, with and without diffraction terms, and (3) rigorous, or full-wave, methods. Physical Optics (PO) Reflector Analysis. 
 TO 
 TO 
 JAMMING SPATIAL ADAPTIVE TECHNIQUES INCLUDING ALSO THE SPACESLOW 
 1471–1483, 2002. 130. R. 
 PULSE  STAGGERED -4)    "IAS AS USED HEREIN REFERS TO THE ERROR IN MEASURING RADAR REFLECTIVITY DUE TO THE CLUTTER NOTCH AND LACK OF FLATNESS  OF THE -4) FILTERS 7HEN WEATHER HAS A WIDE SPECTRAL SPREAD AND THE CLUTTER NOTCH OF THE FILTERS IS NARROW  THERE IS MINIMAL MEASUREMENT ERROR INDUCED BY THE -4) FILTERS #ONVERSELY  WHEN THE WEATHER SPECTRAL WIDTH IS NARROW AND THE RADIAL  VELOCITY OF THE WEATHER IS NEAR ZERO  SIGNIFICANT E RROR IN THE WEATHER REFLECTIVITY MEASUREMENT WILL EXIST  4HERE ARE OTHER CAUSES OF ERROR BETWEEN RADAR ESTIMATES OF PRECIPITATION RATES AND RAIN GAUGE MEASUREMENTS THAT ARE NOT ADDRESSED HEREIN  SUCH AS THE SPATIAL AND TEMPORAL DISTRIBUTION OF RAIN.   -4) 2!$!2  Ó°{Ç %XAMPLES OF WEATHER RADAR APPLICATIONS FOR WHICH -4) FILTERS ARE USED  7EATHER $OPPLER 2ADARS .%82!$732 
 8.18) in contrast to a phase-phase array which uses phase  shifters to steer in both angular coordinates. The antenna may be considered as a number of  frequency-scan arrays placed side by side. In an N by M element planar array there might be a  separate snake feed for each of the N rows to obtain frequency steering in one coordinate. 
 Good ECCM performance is achieved by radiating as large an average transmitter  power at the highest transmitter frequency practicable, coupled with as low a sidelobe  level as achievable. Increasing the transmitter frequency, for a fixed antenna size,  increases the antenna gain Gt, which, in turn, increases the received target power as  Gt2. For main-beam noise jamming, the received jamming power increases directly  as Gt, resulting in a net increase in signal-to-jamming power by a factor proportional  to the antenna gain Gt. 
 A B-scope display is similar to the PPI except that it utilizes rectangular,  rather than polar, coordinates to display range vs. angle. Both the B-scope and the PPI, being  intensity modulated, have limited dynamic range. 
 The final local oscillator, generally referred to as a coherent local oscillator (coho), is often utilized for introducing phase corrections which compensate for radar plat- form motion or transmitter phase variations. Stalo Instability. The stability requirements of the stalo are generally defined in terms of a tolerable phase-modulation spectrum. 
 MINATED  OR AT LEAST ARE ILLUMINATED ONLY VERY WEAKLY 4HIS REQUIREMENT IMPOSES A MINIMUM AREA CONSTRAINT ON THE 3!2S ANTENNA 4HE LOWER AND UPPER BOUND 02& CONSTRAINTS OF " $OP AND 42 LEAD TO  $$ 2 6 C%L !Z 3# )NC      T A NLP    WHERE THE ANTENNA AREA IS THE PRODUCT OF ITS LENGTH  $!Z AND HEIGHT  $%L  AND P  )NC IS THE  MEAN INCIDENT ANGLE IN THE IMAGED SWATH 4HE RANGE 
 The variation of  potential applied to the grid is imparted to the current traveling to the anode. The process by  which tlie electron stream is modulated in a grid-controlled tube to produce amplification is  called cfc~rlsity ~~tocfrtlatiorr.  When the discovery of the cavity magnetron led to the successful development of micro-  wave radar early in World War 11, interest in lower frequency radars waned. 
 TER  ANTENNA  RECEIVER  SIGNAL PROCESSING  AND SO FORTH  THAT MIGHT BE EMPLOYED 4HE RADAR EQUATION IS USED AS AN IMPORTANT GUIDE FOR DETERMINING THE VARIOUS TRADEOFFS AND OPTIONS AVAILABLE TO THE RADAR SYSTEM DESIGNER SO AS TO DETERMINE A SUITABLE CONCEPT TO MEET THE DESIRED NEED 4HIS SECTION  BRIEFLY SUMMARIZES HOW A RADAR SYSTEMS ENGINEER  MIGHT BEGIN TO APPROACH THE CONCEPTUAL DESIGN OF A NEW RADAR 4HERE ARE NO FIRMLY ESTABLISHED PROCEDURES TO CARRY OUT A CONCEPTUAL DESIGN %VERY RADAR COMPANY AND EVERY RADAR DESIGN ENGINEER DEVELOPS HIS OR HER OWN STYLE 7HAT IS DESCRIBED HERE IS A BRIEF SUMMARY OF ONE APPROACH TO CONCEPTUAL RADAR DESIGN 'ENERAL 'UIDELINE  )T SHOULD BE MENTIONED THAT THERE ARE AT LEAST TWO WAYS BY  WHICH A NEW RADAR SYSTEM MIGHT BE PRODUCED FOR SOME PARTICULAR RADAR APPLICATION /NE METHOD IS BASED ON EXPLOITING THE ADVANTAGES OF SOME NEW INVENTION  NEW TECHNIQUE  NEW DEVICE  OR NEW KNOWLEDGE 4HE INVENTION OF THE MICROWAVE MAGNETRON EARLY IN 7ORLD 7AR )) IS AN EXAMPLE !FTER THE MAGNETRON APPEARED  RADAR DESIGN WAS DIFFERENT FROM WHAT IT HAD BEEN BEFORE 4HE OTHER  AND PROBABLY MORE COMMON METHOD FOR CON 
 This  method allows flexibility in optimizing the transmitter aperture distribution, perhaps  for maximum power on the target, and separately optimizing the receiver sum and  difference patterns for low sidelobes. Since a change in feed position corresponds  to scanning with time delay, additional feeds may be added to provide several time- delay-compensated directions of scan for a corresponding increase in bandwidth. The phasing of the antenna has to include a correction for the spherical phase front. 
 A. Wiley, “Synthetic Aperture Radars—A paradigm for technology evolution,” IEEE  Transactions on Aerospace and Electronic Systems , vol. AES-21, pp. 
 S. Gunn, “Scattering of microwaves by a melting spherical  ice particle,” J. Meteorol ., vol. 
  -44 
 DIMENSIONAL RADAR WITH STACKED BEAMS IN ELEVATION   SO THAT IT IS DIFFICULT TO  CANCEL MOVING CHAFF ECHOES ! PULSE DOP 
 In these cases, a much more  accurate track state can be calculated using multiple data streams than using only one  because multiple streams will tend to fill in the gaps in detection and restore a high con - sistent data rate during periods of reduced probability of detection. Figure 7.40 illustrates  the sensitivity to target fades by plotting the track region of uncertainty (ROU) versus the  probability of detection for single radar tracking and multiple radar tracking. The ROU is  defined as the distance that contains the error with 99 percent probability and is ROU = 2.3(tracking error due to detection noise ) + (tracking error due to maneuver ) This can be calculated for any case of interest using the formulas in Table 7.3. 
 TERM RATHER THAN LONG 
 (ILL    3 -USMAN  $ +ERR  AND # "ACHMANN  h!UTOMATIC RECOGNITION OF )3!2 SHIP IMAGES v  )%%%  4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS   VOL   NO   PP n  /CTOBER   7 , 7OLFE AND ' :ISSIS EDS    4HE )NFRARED (ANDBOOK  REV ED  !NN !RBOR  -) %NVIRONMENTAL  2ESEARCH )NSTITUTE OF -ICHIGAN NOW 'ENERAL $YNAMICS  9PSILANTI  -)     - 2ICHARDS  &UNDAMENTALS OF 2ADAR 3IGNAL 0ROCESSING  .EW 9ORK -C'RAW 
 The CF A can be pulse-modulated by turning on and off the high voltage between the  anode (at ground potential) and the cathode (at a large negative potential). This is called  cathode pulsing. The RF drive is usually applied to the CF A before the high voltage is applied  since an RF signal is needed to start the emission process in a secondary-emission cathode. 
 /Ê "- 
 14.2) is also useful for this purpose since it can observe a large  portion of the target track and might even be capable of observing where the target track  originates (airport or seaport), which can be an important classification clue in some  applications.  REFERENCES  l. Goldman, S.: "Frequency Analysis, Modulation, and Noise," p. 
 PULSE DOPPLER FILTER BANK Î°ÈÊ -     "/" Ê " * 
 10. Rowe, A. P.: "One Story of Radar," Cambridge University Press, New York, 1948. 
 STAGE #)# DECI 
 ANGLE CLUTTER FOR OTHER  THAN 8 
 AGE BANDWIDTH AND FAST SETTLING IS REQUIRED  THE MOST COMMON TECHNIQUE IS TO CASCADE A SERIES OF FREQUENCY DOUBLERS OR LOW ORDER MULTIPLIERS 4HIS TYP E OF MULTIPLIER CAN ALSO  PROVIDE NEAR IDEAL PHASE NOISE PERFORMANCE  BUT HAS SIGNIFICANT PHASE MODULATION AS A FUNCTION OF FREQUENCY AS IT CONTAINS FILTERS BETWEEN EACH STAGE OF MULTIPLICATION 0REDISTORTION OF THE MULTIPLIER INPUT WAVEFORM IS OFTEN USED IN ORDER TO PRODUCE  WIDEBAND CHIRP WAVEFORMS WITH LOW RANGE SIDELOBE PERFORMANCE )F THE MULTIPLIER IS CHARACTERIZED BY AN OUTPUT PHASE DISTORTION AS A FUNCTION OF INPUT FREQUENCY GIVEN BY E V   THEN A PREDISTORTION OF THE INPUT SIGNAL BY PHASE  
 66. Howard, D. D.: High Range-Resolution Monopulse Tracking Radar and Applications, EASCON '74  Record, pp. 
 TION KNOWN AS THE  #ASSEGRAIN  THE FOCUS IS A VIRTUAL ONE LYING BEHIND THE SUBREFLECTOR  4HE 'REGORIAN CONFIGURATION PERMITS THE CONSTRUCTION OF A SMALLER APERTURE BETWEEN THE  MAIN CHAMBER AND THE SUBREFLECTOR GALLERY THAN DOES THE #ASSEGRAIN CONFIGURATION ,ARGE COMPACT RANGES SUCH AS THE ONE SHOWN IN &IGURE  ARE VERY COSTLY AND  CAN BE AFFORDED BY ONLY THE LARGEST OF COMPANIES OR THE GOVERNMENT   THUS RANGE TIME IS PREMIUM 3OME COMPANIES KEEP THEIR COMPACT RANGES BUSY  HOURS PER DAY 4ARGETS MEASURED INDOORS ARE PLACED MUCH CLOSER TO  THE RADAR THAN THOSE MEASURED  OUTDOORS  AND USEFUL MEASUREMENTS MAY BE MADE BY USING MUCH LESS RADIATED POWER %ARLY INDOOR INSTRUMENTATION RADARS RELIED ON SIMPLE #7 SOURCES  AND UNDESIRED CHAM 
 Above I-W, the TR tube ionizes  to protect the diode limiter from burnout. More than one diode may be used to provide  greater attenuation or larger bandwidth.  Before the introduction of the solid-state diode limiter, a low-power gas TR-tube, known  as a protector TR, was often used as added protection for the receiver. 
 MODULATED #7 THAT IS TYPICALLY A LINEAR 
 GAIN LOW 
 D. Bilitza, “International reference ionosphere,” http://modelweb.gsfc.nasa.gov/ionos/iri.html. 36. 
 Brunkow, P. C. Kennedy, and D. 
 The lai:ge apertures required for long-range detection result in narrow beamwidths, one of  the prime characteristics of radar. Narrow beamwidths are important if accurate angular  measurements are to be made or if targets close to one another are to be resolved. The  advantage of microwave frequencies for radar application is that with apertures of relatively  small physical size. 
 A tapped delay . 304 INTRODUCTION TO RADAR SYSTEMS  Variable  frequency  signal  Figure 8.18 Volumetric scanning of a planar array using frequency scan in one coordinate and phase-shift  scan in the other.  1 st  mixer  Deloy  T 2d fo L¢  mixer  Fixed t0 frequency >---+---<  oscillator  Variable fc  frequency 1----+---'  oscillator Figure 8.19 Schematic representation of the Huggins  phase shifter. 
 E., et al.: Forward Scattering by Coated Objects Illuminated by Short Wave- length Radar, Proc. IRE, vol. 48, pp. 
 The adversary can achieve this  by choosing any combination of course and speed that makes the velocity component  toward the radar equal to the equivalent phase velocity of the Bragg peak. The radar  operator must counter this by exploiting his understanding of the detailed structure of  the spectrum and its variation with radar frequency to unmask the tar get. Radar Oceanography. 
 7–12. 168. D. 
 22.14 Seasat-A Synthetic Aperture Radar  ...................  22.15  Shuttle Imaging Radar  .......................................  22.15 . 
 The history of radar substantiates this  conclusion. The monostatic radar is the more versatile.of the two. because of its ability to scan  a large volume in space and because of the relative ease with which usable information  concerning the target's position and relative velocity can be extracted from the received signal. 
 I and 2,”  Radio  Science, vol. 6, pp. 517–533, May 1971. 
 These  errors can result in a decrease in gain, increase in the sidelobes, and a shift in the location of the  main beam.  Since it is not always possible to know the exact nature of the errors that might be  encountered in a specific antenna, the properties of the antenna must be described in statistical  terms. That is, the average, or expected, value of the radiation pattern of an ensemble of  antennas of similar type can be computed based on the statistics of the random errors. 
 The electrons follow helical paths around the magnetic field lines when in  the presence of an electromagnetic wave with a transverse component of electric field.  Electrons that lose energy to the electromagnetic wave become lighter and accumulate  phase lead and then catch up with the electrons that gain energy and become heavier  and accumulate phase lag. Thus, electrons become phase-bunched in their cyclotron  orbits as a result of the relativistic mass change of the electrons. 
 Toseethat this isnot sowecanconsider theintegral {f[j’(e)]z de}~~,which isproportional totherms pulse-to-pulse fluctuation TO. Inthecase ofauniform distribu- tion ofscattering elements, thelimits ofintegration arefrom –ccto+~. When there isadiscontinuity yatanangle O,from thecenter ofthebeam, the limits areO,tom,and theintegral will beless than before since the integrand iseverywhere positive. 
 The issue of Do ppler sensitivity was finally considered as shown in Figure  12.30 where a  10 kHz Doppler shift was added to the signal. At S -band this Doppler shift represents a radial  target velocity of 1000knots. For this Doppler shift side lobes have increased but are still b e- low the -55 dB level, while the mismatch loss has increased to 0.59  dB. 
  
 F. L. Fleming and N. 
  PAYLOAD DATA 
 Mechanical Enginet:r­ ing in Radar and Communications," C. J. Richards (ed.), Van Nostrand Reinhold Co., New York,  1969. 
 The autocorrelation function, or output of the matched filter, is shown in (b ). There are six  equal time-sidelobes to either side of the peak, each at a level -22.3 dB below the peak. In (c)  --·----- T = 13 r-------,,..1  r ,._I ;..., r !  1 1+1+1+1+1+1-1-1+1+1-l+l-l+L __  Input to _A_  generate  tronsrn1!  waveform I -r O r  Filler matched  to pulse of  width r (a)  Input for  matched  f ,lier  (cl (b)  13 r  Figure 11.19 (a) Example of a phase-coded pulse with 13 equal subdivisions of either 0°( +) or 1800( -)  phase. 
 Roy. Meteor. Soc., vol. 
 The likelihood ratio is primarily useful in the analysis of the statistical-detection problem.  It is difficult to conceive, however, of a receiver that computes the likelihood ratio directly as  defined by Eq. (10.21). 
 Analternate approach, whichisusuallyeasiertoimplement. istoemploy them-out-of-n detector (thedoublethreshold orbinaryintegrator ofSec. 10.7) withthesecond threshold setatm=(n-1)/2.Themediandetector is..robust," inthatthethreshold values andthedetection probabilities donotdependonthedetailed shapeoftheclutterpdf.butonly onthemedianvalue. 
 []     £    M I N ;     =QQ SN N EK JKJ TT  £ 
 BAND RADARS HAVE USED AN OFFSET PARABOLOID FED BY A RIDGED HORN 4HIS ARRANGEMENT WAS DESIGNED TO FOCUS THE RADIATION INTO THE GROUND AT A SLANT ANGLE TO REDUCE THE LEVEL OF THE REFLECTION FROM THE GROUND #ARE NEEDS TO BE TAKEN IN SUCH  ARRANGEMENTS TO MINI 
 1956-1660, October, 1969.  111. Tatarski, V. 
 A compromise must generally be  made between these conflicting requirements. A target at long range has low angular rates and  a low sigrial-to-noise ratio. A narrow tracking bandwidth is indicated in such a case to increase  sensitivity and yet follow the target with minimum lag. 
 Trunk, and J. D. Wilson, “Tracking system for two asynchronously scanning  radars,” Naval Res. 
 ANE-6, p. 37. Marclr. 
 Waveguide simulators provide a means for determining the element imped- ance in an infinite array with the use of only a few elements. The effectiveness of a matching structure based on these measurements may also be determined in the simulator. 2. 
 Among the advantages of CW radar are its apparent simplicity and the poten- tial minimal spread in the transmitted spectrum. The latter reduces the radio in- terference problem and simplifies all microwave preselection, filtering, etc. A corollary is the ease in the handling of the received waveform, as minimum band- width is required in the IF circuitry. 
 A modulo-two adder is also called an exclusive-or  gate. An rr-stage shift register has a total of 2" different possible states. However, it cannot have  the state in which all the stages contain zeros since the shift register would remain in this state  and produce all zeros thereafter. 
 POWER   WIDTH $ OF THE CLUTTER  VELOCITY SPECTRUM IS QUITE VARIABLE   DEPENDING ON SUCH THINGS AS RADAR POLARIZATION AND SEA CONDITIONS )T SEEMS MOST CLOSELY RELATED TO THE PEAK ORBITAL VELOCITY GIVEN BY %Q  .ATHANSON SHOWS A PLOT CONTAINING SPECTRAL WIDTHS AT BOTH POLARIZATIONS FROM SEVERAL INVESTIGATORS OVER A WIDE ASSORTMENT OF UNSPECIFIED SEA CONDITIONS  4HE POINTS ARE WIDELY  SCATTERED  BUT THE DEPENDENCE ON WIND SPEED IS GIVEN ROUGHLY  WITH A RATHER LARGE VARIANCE  BY THE EXPRESSION  $ ^  5 MS   WHICH IS JUST THE ORBITAL VELOCITY IN  %Q  WITH A COEFFICIENT ABOUT HALFWAY BETWEEN THE VALUES FOR VERTICAL ^    AND HORIZONTAL  ^  POLARIZATION &OR LOOK DIRECTIONS AWAY FROM UPWIND  THE  PEAK DOPPLER FOLLOWS A COSINE DEPENDENCE QUITE CLOSELY  GOING TO ZERO AT CROSSWIND ASPECTS AND TURNING NEGATIVE DOWNWIND  4HE WIDTH OF THE SPECTRUM APPEARS TO  REMAIN RELATIVELY CONSTANT&)'52%    1UALITATIVE BEHAVIOR OF DOPPLER  SPECTRA OF SEA CLUTTER LOOKING UPWIND AT LOW GRAZING  ANGLES AFTER # 
 ofthesignalisthesameastheIFmidband frequencyJ.F'Theoutputof[heenvelope detec~or hasaprobability-density function givenby9 (2.27) R(R2+A2)(RA) pAR)="'0exp-2"'010"'0 where10(Z)isthemodified Besselfunction ofzeroorderandargument Z.ForZlarge,an asymptotic expansion for10(Z)is 10(Z)~-&(1+_1+...)v2nZ 8Z Whenthesignalisabsent,A=0andEq.(2.27)reducestoEq.(2.21),theprobability-density function fornoisealone.Equation (2.27)issometimes calledtheRiceprobability-density function. Theprobability thatthesignalwillbedetected (whichistheprobability ofdetection) isthe sameastheprobability thattheenvelope Rwillexceedthepredetermined threshold VT•The. probability' of detection f', is therefore  This cannot he evaluated by sirnple nleans, and numerical techniques or a series approxima-  tion must be used. 
 6.2 Cosmic and Background Noise   Broadband noise comes from outer space in the form of plane waves.  The antennas then a l- ways receive this noise if the directivity of the main or side lobes poi nts to outer space.  The  noise results from our galaxy, the Milky Way, other galaxies, “Radio Stars and Clusters”, and  from the Sun. 
 Appleton and the Department of  Scientific and Industrial Research had been working  along parallel lines. Appleton had trained a number of  ionosphere workers, who are now continuing and ex-  pandmg ionospheric research in many parts of the  Commonwealth and Empire. The Department had  gathered together and trained a team of young research-  workers, which at the Radio Research Station at Slough  and in the National Physical Laboratory at Teddington  had done work of the highest quality on other aspects  of the physics of radio communication. 
 Later a refinement was made as the target traversed the higher-elevation multipath nulls or "fades." This technique, illustrated in Fig. 20.1«, was extensively employed on early shipborne radars, where advantage could be taken of the highly reflective nature of the sea surface. Of course, the technique was limited in performance by such uncontrollable factors as sea state, atmospheric refraction, target radar cross section, and target maneuvers.1'2 Reflections from the earth's surface were also used by other early contempo- rary ground-based radars, such as the British Chain Home (CH) series, which was employed in World War II for the defense of Britain. 
 Armstrong, and J. Duthie, “The microwave power module: A versatile building  block for high-power transmitters,” Proc. IEEE , vol. 
 Brandwood, “Fourier Transforms,” in Radar and Signal Processing , Boston: Artech House,  2003. 71. G. 
 POWER SWITCH THAT PREVENTS THE TRANSMITTER OUTPUT FROM THE ANTENNAS DUPLEXER  FROM DAMAGING THE SENSITIVE RECEIVER FRONT END &AST RECOVERY IS REQUIRED TO MINIMIZE  DESENSITIZATION IN THE RANGE GATES FOLLOWING THE TRANSMITTED PULSE 20S CAN BE IMPLE 
 The binary code consists of a sequence of either Os and Is or +Is and —Is. The phase of the transmitted sig- nal alternates between 0° and 180° in accordance with the sequence of elements, . TABLE 10.3 Characteristics of VCO Devices *Deviation from an exponential frequency-versus-voltage curve.CommentsMaximum center-frequency stabilityMaximum linearity as percent of deviation, %Maximum frequency devia- tion as percent of center frequency, %Center-frequency range VCO device Requires anode- voltage-control range of 750 to 3000 V. 
 The level of sophistication  used in interpretation varies broadly, ranging from human interpretation of rudimen - tary displays to automatic algorithms and modern multidimensional displays to assist  human interpretation. Expert system approaches106,107 that attempt to reproduce human  interpretive logical processes have been employed effectively. The degree to which  automation can be applied is evident in the Nexrad radar system design that produces  the automated meteorological products shown in Table 19.7. 
 There are two main types of frequency domain radar, Frequency  Modulated Carrier Wave (FMCW) and Stepped Frequency Carrier Wave (SFCW).  FMCW radar transmits a continuously changing frequency over a chosen frequency  range on a repetitive basis. The received signal is mixed with a sample of the transmit - ted waveform and results in a difference frequency, which, although fundamentally  related to the phase of the received signal, is a measure of its time delay and hence  range of the target. 
 (ILL    - 3KOLNIK ED  2ADAR (ANDBOOK  ST %D  .EW 9ORK -C'RAW 
 24.King,D.D.:TheMeasurement andInterpretation ofAntenna Scattering. Proc.IRE,vol.37, pp.770-777, July,1949. 25.Siegel.K.M.:FarFieldScaltering fromBodiesofRevolution, Appl.Sci.Research, sec.B,vol.7, pp.293-328, 1958.. 
 When receiving beams are formed in networks placed after  the RF amplifiers, as in Fig. 8.25, the antenna is sometimes called a poscamplification beam­ forming array, abbreviated PABF A. A separate transmitting antenna may be used to illumin­ ate the volume covered by the multiple receiving beams or, alternatively, it is possible to  transmit multiple beams identical to the multiple receiving beams, using the radiating elements  of the same array antenna. 
 Shaping the frequency resporrs;   on recursive filters employ only feedforward loops. If feed-  back loops are used, as well as feedforward loops, each delay line can provide one pole as well  as one zero for increased design flexibility. The canonical configuration of a time-domain filter  with feedback as well as feedforward loops is illustrated in Fig. 
 Itisolates onetarget.excluding targetsatotherranges.Thispermits theboxcar generator tobeemployed. Also.rangegatingimproves thesignal-to-noise ratiosinceitelimin­ atesthenoisefromtheotherrangeintervals. Hencethewidthofthegateshouldbesufficiently narrowtominimize extraneous noise.Ontheotherhand,itmustnotbesonarrowthatan appreciahle fraction ofthesignalenergyisexcluded. 
 UNAMBIGUOUS 02&S &URTHERMORE  WHEN OPERATING IN THE TRANSMIT 
 Surface Discontinuities.  Most airframes have slots or gaps where control surfaces  meet the stationary airframe. Slots, gaps, and even rivet heads can reflect energy back  to the radar. 
 Clutterfence.Reflections fromnearbymountains andotherlargecluttercansometimes beof suchamagnitude thatitisnotpractical tocompletely suppress theirundesirable effectsby eithcrMTIorrangegating.Onetechnique forreducing themagnitude ofsuchlargecluttcr. 498 INTRODUCTION TO RADAR SYSTEMS  seen by a fixed-site radar is to erect an electromagnetically opaque fence around the radar (or  simply between the radar and the clutter source) to prevent the radar from viewing the clutter  directly. The two-way isolation provided by a typical fence with a straight edge might be about  40 dB, where the isolation is given by the ratio of the clutter signal in the absence of a fence to  that in the presence of the fence. 
 Sensors 2019 ,19, 213 6. Conclusions In this study, an EMAM method has been proposed for DPEC of the VHS airborne SAR imaging. Comparing with the existing MAM-based DPEC methods, the EMAM is superior in achieving higher accuracy beneﬁting from the additional estimation and compensation for the spatial dependence of the third-order Doppler phase, corresponding to the derivative of the Doppler rate. 
 IET Microw. Antennas Propag. 2015 ,9, 1009–1014. 
 MATION HENCE  IT IS VERY  IMPORTANT IN MANY RADAR APPLICATIONS  4HERE ARE TWO TYPES OF  BANDWIDTH ENCOUNTERED IN RADAR  /NE IS THE  SIGNAL BANDWIDTH  WHICH IS THE BANDWIDTH  DETERMINED BY THE SIGNAL PULSE WIDTH OR BY ANY INTERNAL MODULAT ION OF THE SIGNAL 4HE  OTHER IS TUNABLE BANDWIDTH 'ENERALLY  THE SIGNAL BANDWIDTH OF A SIMPLE PULSE OF SINE  WAVE OF DURATION  S IS S 0ULSE COMPRESSION WAVEFORMS  DISCUSSED IN #HAPTER   CAN  HAVE MUCH GREATER BANDWIDTH THAN THE RECIPROCAL OF THEIR PULSE  WIDTH  ,ARGE BAND 
 It can be seen that the point target in side-looking beam is well focused. The proﬁles of range and azimuth-spread function of the target are presented in Figure 12c,d. The PLSR along the range direction shown in Figure 12bi s−13.2231. 
 TEST ")4  SENSORS  OR ADAPTIVE CONTROL COMPONENTS  MAY BE INCLUDED !MPLIFIER  -ODULE $ESIGN  3OLID 
 , vol. 58, pp. 1164–1181, 1977. 
 '(Z PERFORMANCE CURVES FOR A  MM  PERIPHERY 'A. (%-4 &%4 OPERATING AT    6 USING A #7   DUTY  WAVEFORM. 
 This assumes.fr> fa. If, on the other hand,!,. <fa,  such as might occur with a high-speed target at short range, the roles of the averaging and the  difference-frequency measurements are reversed; the averaging meter will measure doppler  velocity, and the difference meter, range. 
 G. V . Trunk, “Survey of radar ADT,” Naval Res. 
 0OLARIZED %NERGY  4ARGET ECHO ENERGY CROSS 
 Those imposed on both transmit  and receive are common . Amplitude instabilities caused by AM tend to be considered independent since  the LOs drive the mixers in the receiver into compression. Also, transmitters work  most efficiently when driven into compression (i.e., where the power amplifier is satu - rated and provides a constant output power level regardless of small deviations on the  input). 
 Therefore the frequency-response function of the portion of the receiver included' between the  antenna terminals to the output of the IF amplifier is taken to be that of the IF amplifier alone.  Thus we need only obtain the frequency-response function that maximizes the signal-to-noise  ratio at the output of the IF. The IF amplifier may be considered as a filter with gain. 
 By proper design, the transformer used between generator and network can incorporate sufficient leakage inductance toresonate with the network capacity at thegenerator frequency. Pulsers ofthis type have been very successful; they arerecommended forcases inwhich specifications arefirmly fixed, suitable repetition rates correspond with available a-c generators, and theuncertain yinfiring time ofarotary spark gap can betolerated.. 384 THEMAGNETRON ANDTHEPULSER [SEC. 
 BAND COUNTERMEA 
 Contents Preface x A note on units xii Acknowledgements xiiiAuthor biography xiv List of abbreviations xv 1 ASV radar development 1-1 1.1 Introduction 1-1 1.2 RAF Coastal Command 1-1 1.3 Airborne radar development and trials organisations 1-2 1.3.1 Post WWII 1-3 1.4 The first airborne radar 1-3 1.5 Outline of the book 1-5 References 1-6 2 ASV Mk. I and II 2-1 2.1 ASV Mk. I 2-1 2.2 ASV Mk. 
 WIDTH OF THE DATA BY A FACTOR 2 WITHOUT AFFECTING THE SIGNAL OF INTEREST  THEN THE 3.2 INCREASE IN D" IS GIVEN BY LOG 2 )N OUR EXAMPLE  A ¾ REDUCTION IN BANDWIDTH  RESULTS IN APPROXIMATELY A  D" INCREASE IN 3.2 7ITH EACH BIT REPRESENTING ABOUT   D" OF 3.2  THE MINIMUM NUMBER OF BITS REQUIRED TO REPRESENT THE FILTERED SIGNAL  COULD GROW FROM  TO  )N AN ACTUAL APPLICATION  THE SYSTEM DESIGNER NEEDS TO ANALYZE  THE EFFECTS OF SAM 
 -Ê  Ê, 
 PLANE DIAGRAM OF A  FEEDFORWARD 
 62. Armstrong, G. M., and R. 
 Describe the field of functions of a duplexer and state a case on that condition given radar  can work without a duplexer.                   3. A frequency -diversity radar with two identically transmitters use one transmitter only. 
 Eachpower­ generating devicehasitsownparticular advantages andlimitations thatrequiretheradar systemdesigner toexamine carefully alltheavailable choiceswhenconfiguring anewradar design. Thetransmitter must beofadequate powertoobtainthedesiredradarrange,butitmust alsosatisfyotherrequirements imposed bythesystemapplication. Thespecialdemands of MTI(moving targetindication), pulsedoppler, CWradar,phased-array radar,EMC 190. 
 Thus, a frustrating paradox of the millimeter-wavelength region is that some of its  claimed good points are also its weaknesses.  Clutter at millimeter wavelengths. In chap. 
 CORRELATION IS APPROXIMATELY EQUAL TO ZERO  3UCH A RADAR IS LESS SUSCEPTIBLE TO A $2&- REPEATER BECAUSE I  THE JAMMER CANNOT ADAPT EASILY SINCE THE RADAR SIGNAL IS VARYING IN THE 02) DOMAIN  AND II  THE SIGNAL TRANSMITTED BY A $2&- REPEATER JAMMER AT A GIVEN 02) IE  THE RADAR SIGNAL THAT IS USED BY THE 3!2 AT THE PREVIOUS 02)  IS APPROXI 
 40Low Observability GROUND TARGET AIR  DEFENSE  RADAR ATTACK APPROACH• Detection range depends on RCS,                   , and therefore RCS  reduction can be used to open holes in a radar network. • There are cost and performance limitations to RCS reduction.   Rmax∝σ4. 
  AIRCRAFT v  *  !TMOS  /CEANIC 4ECHNOL  VOL   PP n    , ,I  ' - (EYMSFIELD  0 % 2ACETTE  , 4IAN  AND % :ENKER  h!  
 Therefore the theory of Fourier transforms can be applied to the  calculation of the radiation or field-intensity patterns if the aperture distribution is known.  The Fourier transform of a function f (t) is defined as  F(f) = I 00  f(t) exp (-j2nft) dt (7.12)  • -00  and the inverse Fourier transform is  f (t) = r 00  f(f) exp (j2nji) df  ·-oo (7.13)  The limits of Eq. (7.10) can be extended over the infinite interval from -oo to + oo since the  aperture distribution is zero beyond z = ± a/2. 
 One book takes uptheuseofradar innavigation, one concerns thedesign ofradar scanners and radomes, one treats thedesign and construction of beacons, and onedescribes hyperbolic navigational systems—in particular Loran. This book isintended toserve asageneral treatise and reference book onthedesign ofradar systems. Noapology seems tobeneeded forthe fact that itdeals primarily-though bynomeans altogether-with micro- wave pulse radar. 
 2.4, Fig. 2.3.) The average-power formulation is especially useful for CW or pulse doppler radars. Antenna Gain, Efficiency, and Loss Factor. 
 7. a = radius of edge contour. 8. 
 ITY OF THE FEEDHORN 4HE SOLUTION WAS TO ADD A SMALLER SUBREFLECTOR IN A SUBTERRANEAN GALLERY BUILT ESPECIALLY FOR IT  AS SUGGESTED IN &IGURE    4HE SUBREFLECTOR HAD THE EFFECT OF GREATLY INCREASING THE FOCAL LENGTH OF THE MAIN  REFLECTOR  MAKING IT EASIER TO OPTIMIZE ITS ILLUMINATION 4HIS PARTICULAR CONFIGURATION IS KNOWN AS A  'REGORIAN SYSTEM  CHARACTERIZED BY A FOCUS  BETWEEN THE TWO REFLECTORS &)'52%   ! COMPACT RANGE USING AN OFFSET PARABOLOIDAL REFLECTOR &)'52%   'ENERIC DUAL 
 RADAR RECEIVERS  6.476x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 Both linear and asymmetrical nonlinear FM produce a range error as a function  of doppler due to range-doppler coupling. These range displacements must match in  the two receivers to within a small fraction of the compressed pulse width; otherwise,  the sensitivity benefits of diplex operation are not fully achieved and range accuracy  may be degraded. Implementation . 
 DETECTED AND PROCESSED THROUGH A CELL 
 TO 
 BAND IMAGING OF A FOREST 4HE FIGURE IS A PLOT OF  F  RATHER THAN  R  F   R COS P    !T LOW FREQUENCIES SUCH AS 6(&  THIS CONDITION CHANGES BECAUSE THE ATTENUATION THROUGH  THE LEAVES AND BRANCHES IS LESS 3OIL -OISTURE  &IGURE  SHOWS THE SIZE OF THE EFFECT OF SOIL MOISTURE ON  R   3OIL MOISTURE EFFECTS DIFFER FOR DIFFERENT SOILS $OBSON AND 5LABY SHOWED THAT THIS  USE OF MOISTURE EXPRESSED IN PERCENT OF  FIELD CAPACITY IMPROVED THE FIT BETWEEN  R  AND  MOISTURE CONTENT &IELD CAPACITY IS A MEASURE OF HOW TIGHTLY THE SOIL PARTICLES BIND THE  WATER THE UNBOUND WATER AFFECTS  D  MORE !N EMPIRICAL EXPRESSION FOR FIELD CAPACITY  &#  IS   &#     
 The vibrations ofthe crystal are communicated tothe mercury asasuper- sonic wave which travels down the tube ataspeed of4700 ft/see, Inputoutput corresponding toadelay of17.6 psec/in. Onarriving attheother +4- Delaylength~ end ofthe line the wave causes17.6pseclin. $ the receiving crystal tovibrate, and this vibration produces an alternating voltage between the faces ofthe crystal.15Me/see X.cutquartzplates, The mercury end cells, inaddi- oneinchdiameter tion toacting aselectrodes, serve also toprevent reflection ofthe Mercury Mercury supersonic wave bythe crystals. 
 Shaping the  underside of tlie 211 transmitting antenna to minimize the energy illuminating the surface can  OTHER RADAR TOPICS545 oftime.Thisissimilartotheeffectofamplitude fluctuations ontracking radar,asdiscussed in Sec.5.5.Iffrequency scanisused.thereisevenrnorelikelihoodofecho fluctuations because of thechange intargetechowithfrequency. Another method forobtaining 3Dcoverage withascanning pencilbeamistoemploy helicalscan.asintherenowned SCR-584 ofWorldWarII.Asinglepencilbeamisrotated in azimuth withitselevation angleincreased onebeamwidth perrevolution soastotracea helicalpattern.Itisasimpletechnique. butisnotofhighaccuracy sinceitisdifficult to interpolate hetween adjacent elevation beampositions. 
 2, June, 1954.  2. Van Vleck, J. 
 Care must be taken inantenna installation tomake sure that the axis ofequal signal coincides with the direction offlight ofthe aircraft. “Squint,” which Left Right antenna ntenna Leftantenna Sightantenna (a)(b) FIQ. 629.-Beam patterns ofASV Mark II(SCR-521). 
 ch07.indd   50 12/17/07   2:15:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 Benedict72suggests thattominimize theoutputnoisevariance atsteadystateandthetran­ sientresponse toamaneuvering targetasmodeled byarampfunction, theex-pcoefficients are relatedbyf1=ex2/(2-ex).Theparticular choiceofexwithintherangeofzerotoonedepends uponthesystemapplication, inparticular thetracking bandwidth. Acompromise usually mustbemadebetween goodsmoothing oftherandommeasurement errors(requiring narrow handwidth) andrapidresponse tomaneuvering targets(requiring widebandwidth). Another criterion forselecting theex-fJcoefficients isbasedonthebestlineartrackfittedtotheradar datainaleastsquaressense.Thisgivesthevaluesofexand/3as74 2(2n-I)ex=--_._-- 11(11+I)6 /3=n(1I+1) whereIIisthenumber ofthescanortargetobservation (11>2). 
 Theoperation oftheFM-CW radardescribed earlierinthissection doesnotemployoptimum signalprocessing, suchasdescribed inChap.10.Thereceiver isnot designed asamatchedfilterfortheparticular transmitted waveform. Therefore, thesensitivity oftheFM-CW receiver described hereisdegraded andtheabilitytooperate withmultiple targetsisusuallypoor.Foraradioaltimeter whosetargetistheearth,theselimitations usually presentnoproblem. Whenusedforthelong-range detection ofairtargets,forexample, the nonoptimum detection oftheclassical FM-CW radarwillseriously hinderitsperformance whencompared toaproperly designed pulseradar.Itispossible, however, toutilizematched­ filterprocessing intheFM-CW radarinamannersimilartothatemployed withFM(chirp) pulsecompression radarasdescribed inSec.11.5,andthusovercome thelowersensitivity and multiple-target problems. 
 G. Bath, “A retrospective detection algorithm for extrac - tion of weak targets in clutter and interference environments,” in IEEE Int. Radar Conf ., London,  1982, pp. 
 Radar System Engineeri ng Chapter 8 – Pulse Radar  49     8 Pulse Radar  8.1 The History of Pulse Radar   The first pulse Radars had a very low pulse repetition rate.  On one side, one could not create a  higher pulse rate and on the other side, one could not process it.  After the Second World War  the pulse repetition rate could be incrementally increased as much as the demanded, unique  range of coverage permitted. 
 T. Blackband (ed.). Gordon and Breach Science Publishers, New  York. 
 2002 ,11, 1260–1270. 26. Coupe, P .; Hellier, P .; Kervrann, C.; Barillot, C. 
 [ CrossRef ][PubMed ] 12. Wang, C.; Guo, W.; Zhao, H.; Chen, L.; Wei, Y.; Zhang, Y. Improving the Topside Proﬁle of Ionosonde with TEC Retrieved from Spaceborne Polarimetric SAR. 
 A  o 01 r I I r r 1111 I I I 11 111 I I I 11 111  0.1 1.0 10 100  Frequency, gigacycles  Figure 2.28 Theoretical (one-way) attenuation of RF transmission lines. Waveguide sizes are inches and  are tlie inside dimensions. (Data ,from Armed Services Index of R.F. 
 However, the classic Radar Observation of the Atmosphere  by Lou Battan20 deserves  special mention for its clarity and completeness and remains a standard for courses in  radar meteorology. The Battan Memorial and 40 th Anniversary Radar Meteorology   Conference  produced a collection of review papers, Radar in Meteorology,21 covering  the first four decades of radar meteorology from the historical, technological, scientific,  and operational perspectives. Bean et al.22 in Skolnik’s first Radar Handbook  addressed  the problem of weather effects on radar. 
 As time passed, the demands for improved radar performance outran the capabilities  available from the magnetron. Fortunately, other tube types were invented that over - came the limitations of the magnetron. Although the magnetron has had important applications in the past, it has also had  serious limitations that constrain its usefulness for radar. 
 ELEMENT ARRAY  IT IS CLEAR THAT THE GAIN VARIA 
 Reintjes, J. F .. and G. 
 FIG. 23.4 Artist's depiction of a microburst and its effect on an aircraft during takeoff. The loss of airspeed near to the ground can be extremely haz- ardous. 
 TRACK ASSOCIATION IS TO CORRECTLY ASSIGN RADAR DETECTIONS TO EXISTING TRACKS SO THE TRACK  STATES IN THE TRACK FILE CAN BE CORRECTLY UPDATED 4HE BASIS FOR ASSIGNMENT IS A MEASURE OF HOW CLOSE TOGETHER THE DETECTION AND TRACK ARE  IN TERMS OF MEASURABLE PARAMETERS SUCH  AS RANGE  ANGLE  DOPPLER  AND  WHEN AVAILABLE  TARGET SIGNATURE 4HE STATISTICAL DISTANCE IS CALCULATED AS A WEIGHTED COMBINATION OF THE AVAILABLE DETECTION 
 LEVEL POWER REGULATION  FILTERING  LOGIC  CALIBRATION TABLES AS WELL  AS THE OBVIOUS 2& FUNC 
 Ê­- 1 / 
 For a round reflector of diameter D, this aperture gain  limit is  apGD=  π λ2  (12.7) In practice, it is sometimes useful to describe reflector gain by decrementing the  aperture gain by subtracting various aperture radiation losses such as spillover, taper  efficiency, feed blockage, reflector leakage, surface distortion, strut blockage, feed align - ment, etc., from Gap. These loss factors are described in detail later within this section. Directive Gain and Feed Losses. 
 MINATION OF THE SOURCES OF SCATTERING FROM VEGETATION CANOPIES AT  '(Z v PTS ) AND ))   )NT *  2EMOTE 3ENSING  VOL   PP n    , + 7U  2 + -OORE  AND 2 :OUGHI  h3OURCES OF SCATTERING FROM VEGETATION CANOPIES AT    '(Z v )%%% 4RANS  VOL '% 
 ORDER CONTRIBUTIONS&)'52%   #ALIBRATED MEASUREMENTS OF THE RATIO OF THE MEASURED SCATTERING COEFFICIENT TO THE  SATURATED SEA SCATTERING COEFFICIENT  PLOTTED AS A FUNCTION OF THE RATIO OF WIND SPEED TO THE PHASE SPEED OF  THE "RAGG 
 AGE 4HIS CHANGES THE NUMBER IN THE RANGE REGISTER TOWARD THE VALUE CORRESPONDING TO THE RANGE OF THE TARGET 2ANGE READOUT IS ACCOMPLISHED BY READING THE NUMBER IN THE REGISTER  WHERE  FOR EXAMPLE  EACH BIT MAY CORRESPOND TO A  
 AP-33, pp. 286–294, March 1985. 31. 
 8.4.  tiie echo from a target is freqi~ency niodulated when illuminated by such a frequency-scanned  bcarn. Pulse-compression filtering (similar to chirp) can be used to achieve a range resolution  equal to the reciprocal of tiie one-way group delay along tlie dispersive delay line (snake feed)  feeding the frequency-scar1 array. 
 1/PRF 1/fp. 35Low, High, Medium PRF • If fdis increased the true target Dopple r shifted return moves out of the  passband and a lower sideband lobe ente rs.  Thus the Doppler measurement is ambiguous. 
 INDUCED ERRORS &OR EXAMPLE  A TYPICAL  
 will give little or no return. The radar cross  section of a farnler's ficld will differ before and after ploughing, as well as before and after  tlarvesting. It will also depend on tlie direction of tlie radar beam relative to the direction of  tlie ploughed furrows. 
 It is important to recognize that timing jitter does not produce equal impact on all . parts of the echo pulse and generally has minimal effect on the center of the pulse; so it is essential to collect data samples at a multiplicity of points across the echo, including leading and trailing edges. The total radar instability is the ratio of the sum of the multiplicity of residue powers at the output of the doppler filter to the sum of the powers at its input, divided by the ratio of receiver noise at these locations. 
 IZED TO THE RADAR ANTENNA CAUSES CROSSTALK CROSS COUPLING  IN RADARS IE  THE AZIMUTH ERROR CAUSES OUTPUT FROM THE ELEVATION 
 A hyperbolic measurement system can be used, in which a receiver measures the difference in propagation times from two separate transmitters. The locus of target position now lies on a hyperbola, and the inter- section of the receiver's AOA (angle of arrival) estimate with the hyperbola es- tablishes the target position. Use of a third transmitter provides a full hyperbolic fix on the target. 
 Hence it does not preserve the shape of the input waveform. (There is no reason to  wish to preserve the shape of the received waveform so long as the output signal-to-noise ratio  is maximized.)  Let us return to tlie receiver output as represented in Fig. 2.1. 
 Typically, a 50-ft radome can be installed at a prepared site in about  one or two hours.1 35 They are also of interest on static sites where wideband frequency  operation is desired. One of the largest examples o( an air-supported radome was the 210 ft  diameter radome for the Bell Telephone System Telstar satellite communication antenna at  Andover, Maine.  Air-supported radomes have a number of disadvantages. 
 The  angles 0, </J are those usually employed in classical antenna theory and are defined in Fig. 7.28.  They are not to be confused with the usual elevation and azimuth angles. 
 E.: Statistical Parameters for Scattering from Randomly Oriented Arrays, Cylinders, and  Plates, IEEE Trans., vol. AP-18, pp. 68-75, January, 1970. 
 L. MacArthur, "The Navy  GEOSAT Mission Radar Altimeter Satellite Program , Monitoring Earth's  Ocean, Land and Atmosphere from Space-Sensor s, Systems and Applications,"  Prog. Astronaut. 
 Initial configuration of the Space Station will have limited tracking-system re- quirements that include tracking of cooperative vehicles within a 37-km control zone.63 This is based upon the assumption that all vehicles will provide accurate position and velocity data to the space station tracking system by way of the space-to-space link. Automatic tracking of an extravehicular (EV) astronaut is not required. For growth configurations of the Space Station, the tracking systemTABLE 22.7 Space Radiation Environment Summary* *From Ref. 
 DOM IN NATURE 4HE ORDER OF FREQUENCIES IS THE CODE  AND IT IS GENERATED VIA A SPECIAL CLASS OF - ¾ - #OSTAS ARRAYS #OSTAS   SUGGESTED A TECHNIQUE FOR SELECTING THE ORDER OF THESE  FREQUENCIES TO PROVIDE MORE CONTROLLED RANGE AND DOPPLER SIDELOBES !N EXAMPLE OF A #OSTAS CODE OF LENGTH  IS SHOWN IN &IGURE   AS IT COMPARES TO THE STEPPED ,&- 4ABLES SHOWING THE SEQUENCE ORDER FOR EACH WAVEFORM ARE ALSO PROVIDED  n°ÎÊ  /",-Ê 
 Any use is subject to the Terms of Use as given at the website. Bistatic Radar.  BISTATIC RADAR  23.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23Year  reportedRef Organization Author Surface Composition# Data  Curves /  FiguresFrequency  (GHz)Measurement Angles (degrees) Polarization      qi      qs     f 197797  197898  197999 The University  of Michigan  (ERIM)Larson,  Heimiller,  et al. Grass with cement  taxiway     Weeds and scrub trees Orchard, weeds, scrub   trees w/ snow cover16 / 8       10 / 5   146 / 1461.3, 9.4       1.3, 9.4   1.3, 9.4HH HV       HH HV   HH HV50 – 80   70,75, 80   70, 75, 80   50 – 80   60, 70, 80   60 – 8085  80  70  85  60 – 84   60 – 800 – 105   0 – 180  0 – 105   0 – 105   0 – 180  0 – 180 1979100 Raytheon Co. 
 Itisalsopossible tousetheamplitude fluctuations torecognize thedopplercomponent produced byamovingtarget.MTIradarwhichusesamplitude insteadofphasefluctuations is callednoncoherent (Fig.4.33).Ithasalsobeencalledexternally coherent, whichisamore descriptive name.Thenoncoherent MTIradardoesnotrequireaninternalcoherent reference signaloraphasedetector asdoesthecoherent formofMTI.Amplitude limitingcannotbe Tocancellation circuits Figure4.33Blockdiagramofanoncoherent MTIradar.. en~ployed in tile ~ioncollere~it MTI receiver, else the desired anlplitude fluctuations would be  lost. Therefore tile IF amplifier must be linear, or if a large dynamic range is required, it can  be logarithmic. 
 of observation lies on the diffraction cone, no value is assigned the diffracted field. The scattering direction in backscattering problems is the reverse of the di- rection of incidence, whence the diffraction cone becomes a disk, and the scat- tering edge element is perpendicular to the line of sight. The amplitude of the diffracted field is given by the product of a diffraction coefficient and a divergence factor, and the phase depends on the phase of the edge excitation and on the distance between the observation point and the dif- fracting edge element. 
 The switched-line pllase  shifter uses rriore diodes than the other types and has an undesirable phase-frequency response  which can k corrected at the expense of a higher insertion loss. This configuration is generally  restricted to true-time-delay circuits and to low-power, miniaturized phase shifters where loss  is not a rrlajor curlsideration. For a four-bit phase shifter, covering 360°, the minimum number  of diodes needed in the periodically loaded line is 32, the switched line requires 16, and the  hybrid-coupled circuit needs only 8. 
 IEEE Geosci. Remote Sens. Lett. 
 This insures aconstant intermediate frequency and avoids any tuning problems. Frequency-doubling isemployed inthe modulator toavoid difficulties inkeeping leakage from the crystal oscillator out ofthe i-famplifier. Transmitting Receiving antennaantenna 3000Me/see I Oscillator30Mclsec2ndi.fdetectoramplifler1 FIG.5.5.—Block diagram ofsimple doppler-type radar system. 
 False Alarm Rate   A false alarm is “an erroneous radar target detection decision caused by noise or other interfering  signals exceeding the detection threshold ”. In general, it is an indication of the presence of a radar  target when there is no valid target. The False Alarm Rate (FAR) is calculated using the following  formula:     false targets per PRTFARnumber of  rangecells   False alarms are generated when th ermal noise exceeds a pre -set threshold level, by the presence  of spurious signals (either internal to the radar receiver or from sources external to the radar), or by  equipment malfunction. 
 TO 
 8.6shows theAN/UPX-l, a10-cm beacon that was similarly used. Similar beacons have been used formarking liferafts atsea.. 250 RADAR BEACONS [SEC. 
 Refocused images of ship02 sub-image. ( a) Sub-image of ship02; ( b) Refocused image with the DCT method; ( c) Refocused image with the PGA method; ( d) Refocused image with the proposed method. 285. 
 Radar Senso rData Processin gObjec t ListTracking , Histor yTarget : Range SpeedVehicl e Contro l Vehicl e Speed Accel . Torqu eDynamic :DataRaw    Figure 13.20  Scheme for processing with ACC Radar sensors.   13.3.6  Reflection Cross -Section in Street Traffic at 76 GHz   Obstacles in traffic can range from stones to trucks with flat, metallic rear walls. 
 OF 
 HANDED CIRCULARLY POLARIZED 2(#0  WAVE WILL BE REFLECTED AS A LEFT 
 Thus the saturation limit of !he  computer will be reached if it is given too many data points per unit time. This is more likely to  occur with short-range targets since they generally require a higher data rate !han long-range  targets.  In order to maintain maximum effectiveness of the radar and its computer when overload­ ing occurs, some sort of priority system is required. 
 AP-26, pp. 618-62 1,  July, 1978.  68. 
 Another option is to install a series  of low radar fences  across the range. The design objective is to block ground-reflected  rays from reaching the target from the radar, and vice versa, by shielding the specular  zone on the ground from both. The near sides of the fences should be slanted to deflect  energy upward (out of the target test zone) and may be covered with absorbing mate - rial. 
 36, pp. 222-226, April,  1964.  66. 
 SCATTERING CROSS 
 X D"   4HE RANGE RESOLUTION IS EQUAL TO  C TIMES THE CORRESPONDING TIME DELAY RESOLUTION  WHERE C IS THE SPEED OF LIGHT 4ABLE  CONTAINS A SUMMARY OF THE RESOLUTION WIDTHS  FOR THE ,&- WAVEFORM ,&- 7AVEFORM %XAMPLES  &IGURE  SHOWS THE MAGNITUDE OF THE AUTOCORRELA 
 6. The slope of the leading edge varies with wave  height, and the half-power point corresponds to mean  sea level. The tracker operates to center the fast-rising  leading edge of the ocean return within the 60 samples. 
 4.Bennett. W.R.:Methods ofSolving NoiseProblems, Proc.IRE,vol.44,pp.609-638, May.1956. 5.Davenport. 
 LIERS IE  LARGE ERRORS NOT DESCRIBED BY THE GAUSSIAN DENSITY   4RUNK AND 7ILSON ARGUED THAT THE DECISION SHOULD BE BASED ON THE PROBABILITY  0 J   PROBABILITY : q DJ     WHERE : HAS A CHI 
 The  destination port and ETA can sometimes be useful in determining the likely intentions  of targets, although such assumptions must be treated warily. A significant advantage of radar is that it does not need cooperative targets. It  attempts to detect all objects of potential interest. 
 J. Chappell, and R. Batty: The Measured and Calculated RCS ofa Resistive Target  Model, IEE (Londorr) Radar-77, pp. 
 18.48  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 phase so that the radiated polarization is circular (either left or right). The received  linear polarizations are maintained through the remainder of the system to the image  processor output products. This results in the hybrid-polarity architecture111 that is  outlined below. 
 Rade·r (eds.): "Digital Signal Processing," IEEE Press, New York, 1972.  17. Gardner, F. 
 Syst. 1996 ,32, 1185–1191. [ CrossRef ] 22. 
 4. T. D. 
 Angle (deg) Noise (dBW)• = R4th Loss• = R4th + L 0 = Frequency* = Q. Angle ^ 1 deg.* = Noise• = R4th Loss. = R4th + L 0 = Frequency* = El. 
 ARRAY OUTPUTS WEIGHT RESCALING   !S AN EXAMPLE CONSIDER A LINEAR ARRAY OF  ELEMENTS AND RAISED  COSINE TAPERING &IGURE  DEPICTS THE FOLLOWING #ONTINUOUS CURVE PATTERN OF ARRAY      4HE SUB 
 When heavy clutter is present, the SLC and adaptive  array will attempt to minimize the power in the adapted output without differentiat - ing between clutter and other forms of interference. In other words, the adapted pat - tern will contain nulls steered in the direction of the main-beam antenna. A number  of techniques may be used to avoid the problems raised by the presence of clut - ter. 
 FIG. 12.2 Ground area and projected area.RADAR PROJECTED AREA GROUND AREA . tation, with the Kansas measurements also including some work on snow and extensive work on sea ice. 
 Theinformation writtenontheinsulator storage surfaceformsachargepatternthatismadevisiblebytheactionofthefloodbeam.Atthose pointswheretheactionofthewritingbeamreducesthepotential ofthestoragemedium sufficiently, theelectrons fromthefloodbeamareallowed topassthrough andreachthe viewingscreen.Thedisplayiscontinuous sincethephosphor iscontinuously excitedinthe writtenareasbythefloodbeam. .J Aresolution ofabout80linesperinchwithascreenbrightness of200foot-lamberts canbeobtained. Thepersistence canbevariedfromafraction ofasecondtoseveral minutes, orlonger.31Fromfivetosevengray-scale rangesaretypical.26Thedirect-view storagetubecanalsobeobtained withtwocolorsandtheshadesinbetween.3o Thedirect-view storagetubegenerally iscapableoflessresolution thanaconventional CRT.Also,thecontinuous buildup onthestoragemedium ofstrong,fixedclutterechoes whenthepersistence islongcanresultinalossofpicturequalityduetoalossofresolution andalossofcontrast causedbythebrightening ofthedarkareaimmediately surrounding theblip. 
 Publ. 281, pp. 22-25, 1987. 
 It becomes  *  Sky noise consisting of sun, galactic, and atmospheric noise is another source of RFI, which can increase the  receiver’s noise temperature by a factor of 2–4 at frequencies below ~400 MHz.30 However, this increase is usually  orders of magnitude smaller than RFI from other sources and can be ignored. ch23.indd   30 12/20/07   2:21:53 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Papathanassiou, “Polarimetric SAR interferometry,” IEEE Trans  Geoscience and Remote Sensing , vol. 36, pp. 1551–1565, 1998. 
 Gray, Jr., “Computer-aided fault determination for an advanced phased  array antenna,” presented at Proc. Antenna Application Symp., Allerton, IL., September 1979. 23. 
 ADC datasheets specify the spur-free dynamic  range (SFDR) of the device, which is typically defined as the dB difference in signal  level between the desired signal and the largest spur measured at the ADC output  with a single tone applied to the input. The SFDR of a typical ADC is higher than its  specified SNR. Unfortunately, there are many definitions of SFDR, so the designer  is advised to read manufacturers’ datasheets carefully in this regard. 
 (2.8) is the optimum-bandwidth (matched-filter) value of (S/N)min, which North showed to be equal to D0. It is this fact that al- lows the range equation to be written, as desired, in terms of the signal-to-noise ratio at the detector input terminals (filter output) rather than the ratio at the an- tenna terminals. North deduced that Bnopi = I/T exactly. 
 In addition to the improved sensitivity, the variable scanner speed (see comment above) of ASV Mk. VI was considered an advantage when searching and a speed of 30 rpm was recommended for normal use. 4.7.1 ASV Mk. 
 MUTH  BUT THE EXISTENCE OF MULTIPLE PATHS FOR SIGNAL RECEPTION  TYPICALLY VIA THE %  &  AND & LAYERS  HAS MOTIVATED SOME DESIGNERS TO EMPLOY TWO 
 Remote Sens. Environ. 2012 ,117, 429–439. 
 DOMAIN  WEIGHTING IN STRETCH PROCESSING AND PROVIDES DETAILS ON COMPENSATION TECHNIQUES FOR  HARDWARE ERRORS 4HE EFFECT OF TIME MISMATCH BETWEEN THE SIGNAL AND THE WEIGHTING FUNCTION IS ANALYZED BY 4EMES . 
 §©¶¸ 
 FREQUENCY OSCILLATOR TO INCREASE OR DECREASE THE COUNT IN THE RANGE REGISTER  DEPENDING ON THE POLARITY OF THE ERROR VOLT 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°£x IS SOMEWHAT MORE DIFFICULT TO IMPLEMENT CONSEQUENTLY  THE MEAN DEVIATE DEFINED BY  SM £ 
 17, no. 2, pp. 25-33,  Summer. 
 The direction of propagation  is along the tube, and contours of equal phase are perpendicular to it. In a lossless  medium, all the energy entering the tube at one end must come out the other end, but  energy losses within the medium may also be accounted for. An incident wave may be  represented as a collection of a large number of rays, and when a ray strikes a surface,  part of the energy is reflected and part is transmitted across the surface. 
 The most  important facts concerning these detectors are the following: ● The detection performances of the linear and square-law detectors are similar, dif - fering only by less than 0.2 dB over wide ranges of PD, Pfa, and n. ● Because the signal return of a scanning radar is modulated by the antenna pattern, to  maximize the S/N when integrating a large number of pulses with no weighting (i.e.,  Ai = 1), only 0.84 of the pulses between the half-power points should be integrated,  and the antenna beam-shape factor (ABSF) is 1.6 dB.4 The ABSF is the number by  which the midbeam S/N must be reduced so that the detection curves generated for  equal signal amplitudes can be used for the scanning radar. ● The collapsing loss for the linear detector can be several decibels greater than the  loss for a square-law detector5 (see Figure 7.1). 
 ELEMENT GRID CONTAINING    ELEMENTS B  0ATTERN FOR A THINNED ARRAY  3! IS THE AVERAGE SIDELOBE LEVEL  AFTER    2 % 7ILLEY Ú )2%  #OURTESY OF  "ENDIX 2ADIO  . 
 Eng., vol. 93, pt. IIIA,  pp. 
 Parashar, S. K., R. M. 
 THIRD SCALE MODEL # 
 To combine data from multiple radars, the data must be placed in a common coor - dinate system. This process is called grid locking  and involves specifying the location  of the radars and estimating radar biases in range and angle. The previous difficult  problem of radar location is solved trivially by the global positioning system. 
 12. Bean, B. R., E. 
 NOISE AMPLIFIERS ,.!S  ARE INCLUDED IN THE ANTENNA  PRIOR TO FORMING  THE RECEIVE BEAMS  THE ANTENNA SIDELOBE LEVELS ACHIEVED ARE DEPENDENT UPON THE DEGREE TO WHICH GAIN AND PHASE CHARACTERISTICS ARE SIMILAR IN ALL ,.!S $YNAMIC RANGE HAS AN EXAGGERATED IMPORTANCE IN SUCH CONFIGURATIONS BECAUSE MATCHING NONLINEAR CHAR 
 / 
 383-386, McGraw-Hill Book Company, New York, 1948.  6. Palma-Vittorelli, M. 
 KM SWATHS ARE OFFSET  KM FROM NADIR  SPANNING  nnn n INCIDENCE 4HE  D" RADIOMETRICALLY ACCURATE DATA ARE AVERAGED TO ACHIEVE  + P  FROM  HIGH UP 
 The impedance of an ele - ment in an array has been discussed and has been shown to vary as the array is scanned.  An array that is matched at broadside can be expected to have at least a 2:1 VSWR at  a 60° angle of scan. To compensate for the impedance variation, it is necessary to have  a compensation network that is also dependent on scanning. 
 DOPPLER  COUPLING. n°È  2!$!2 (!.$"//+  &)'52%    ,&- WAVEFORM AUTOCORRELATION FUNCTION 4    §S   "    -(Z    4"     &)'52%    ,&- WAVEFORM AUTOCORRELATION FUNCTION  4    §S   "    -(Z    4"     TO  -(Z§S )N THIS CASE  A DOPPLER SHIFT OF  -(Z SHIFTS THE PEAK OF AUTOCOR 
 BISTATIC RADAR  23.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 If Eq. 23.8 is satisfied, extraordinary measures are usually required to suppress the  direct path signal to a level where targets can be detected, as outlined in Section 23.9. 23.4 APPLICATIONS Ovals of Cassini can be used to define three operating regions for a bistatic radar, co- site, receiver-centered , and transmitter-centered .1 Co-site corresponds to Figure 23.2 b;  receiver-centered to the right oval in Figure 23.2 d; and transmitter-centered to the   left oval in Figure 23.2 d. 
 Now that we have studied the basic principles of radar  . 134. HOW RADAR WORKS  equipment we can progress to a more detailed investiga-  tion of practical systems. 
 Squint mode increases the di ﬃculty of SAR signal processing and can also provide more possibilities in terms of applications with corresponding imaging methods. In this paper it is a novel application for azimuth sidelobes suppression based on MPS SAR mode; it can Sensors 2019 ,19, 2764; doi:10.3390 /s19122764 www.mdpi.com /journal/sensors 39. Sensors 2019 ,19, 2764 suppress azimuth sidelobes signiﬁcantly and improve the azimuth resolution slightly simultaneously. 
 For a  medium-resolution X-band radar at low grazing angles, the time required for the sea clutter  echo to decorrelate is about 10 ms.16•21 Any pulses received from sea clutter during this time  will be correlated and no improvement in signal-to-clutter ratio will be obtained by intl.!gra­ tion. (This is unlike receiver noise since integration of signal pulses and noise can provide  significant improvement in signal-to~noise ratio, as described in Sec. 2.6.) Although the clutter  received during a single scan past a target wilt be correlated, the sea surface will usually chang~  by the time of the next antenna scan so that the clutter will be decorrelated from scan to scan. 
 Therearethreegeneral classesofambiguity diagrams, Fig.11.13.Theknifeedge,orridge,isobtained withasinglepulseofsinewave.Itsorientation isalongthetime-delay axisforalongpulse,alongthefrequency axisforashortpulse,oritcan berotatedtoanydirection intheTR,Jdplanebytheapplication oflinearfrequency modula­ tion.ThebedofspikesinFig.11.13bisobtained withaperiodic trainofpulses.TheinternaI structure ofeach ~fthemajorcomponents, illustrated figuratively bythesimplearrows, depends onthewaveform oftheindividual pulses.Thethumbtack ambiguity diagram, Fig.11.13c,isobtained withnoiseorpseudonoise waveforms. Thewidthofthespikeatthe centercanbemadenarrowalongthetimeaxisandalongthefrequency axisbyincreasing the bandwidth andpulseduration, respectively. However, theplateauwhichsurrounds thespikeis morecomplex thanillustrated inthesimplesketch.Withrealwaveforms, thesidelobes inthe plateauregioncanbehigherthanmightbedesired.Furthermore, theextentoftheplatform increases asthespikeismadenarrower sincethetotalvolumeoftheambiguity function must beaconstant, aswasgiven'byEq.(1L54).Therecanbemanyvariations ofthesethreeclasses, asillustrated inRef.11. 
 STANT SHOULD BE SIGNIFICANTLY LESSER OR GREATER THAN THE HOST SOIL 4YPICALLY  MOST SOILS EXHIBIT A RELATIVE DIELECTRIC CONSTANT  WHICH RANGES BETWEEN  TO  &RESH WATER HAS A RELATIVE DIELECTRIC CONSTANT OF APPROXIMATELY  )T SHOULD BE NOTED THAT THE GROUND AND SURFACE ARE QUITE LIKELY TO BE INHOMOGENEOUS AND CONTAIN INCLUSIONS OF OTHER ROCKS OF VARIOUS SIZE AS WELL AS MANMADE DEBRIS 4HIS SUGGESTS THAT THE SIGNAL TO CLUTTER PER 
 A. Marki: Thin-Film Mixers Team Up To Block Out Image Noise, Micro­ waves, vol. 11, pp. 
 Tamama, and N. Yamauchi: A Japanese 3-d Radar for Air Traffic Control.  Electronics, vol. 
 Note now thesignificance ofthethree curves inthat figure which correspond todifferent pulserepetition jrequew”es with the same total time ofobservation. Anincrease inPRF byafactor of16, from one curve tothe one below, reduces the signal power required by very nearly afactor of4. Itisnatural toassume that, whatever the effective number ofintegrations, itisproportional tothe PRF, for constant observation time, and wemay regard theexperiments described byFig. 
 Metal spheres are used rou - tinely as calibration targets for RCS measurements because an exact solution is  available; metal spheres are not very hard to build; and efficient computer codes are  available for obtaining the exact solution. No other scattering body affords all these  conveniences. Integral Equations. 
 PULSE FREQUENCY AGILITY  THE CENTER FREQUENCY OF EACH TRANSMITTED PULSE IS MOVED  IN EITHER A RANDOM OR A PROGRAMMED SCHEDULE  BETWEEN A LARGE NUMBER OF CENTER FREQUEN 
  
 Typical examples of radar images at  various scales are shown in Figure 21.32 and Figure 21.33. GPR has been used for surveying many different types of geological strata rang - ing from exploration of the Arctic and Antarctic icecaps and the permafrost regions  of North America, to mapping of granite, limestone, marble, and other hard rocks as  well as geophysical strata. The radar data shown in Figure 21.34 were collected at  Finsterwalderbreen glacier, Svalbard, Norway, which is an island almost 80° north  of Norway. 
 OBSERVING 3"2S  SUCH AS 3!2S  TEND TO OPERATE FROM SPACECRAFT IN NEAR 
 A. S.: The Radechon. A Barrier Grid Storage Tube, RCA Rev., vol. 
 Their 770 kg mass (total dry mass of the spacecraft and the radar) is less than  the mass of RADARSAT-2’s antenna! The SAR-Lupe design also is cost-conscious,  based on rigid (nondeployed) reflector antennas (“borrowed” from a commercial  communications satellite production line) that are inherently more efficient and less  massive than an active array. The radar electronics are directly descended from a  commercial product line. RISAT . 
 ACTERISTIC !S AN EXAMPLE  THE !NALOG $EVICES !$ $IRECT $IGITAL 3YNTHESIZER  USES A   
 RANGE CONSIDERATIONS MUST TAKE INTO ACCOUNT AT LEAST SOME THREE ORDERS OF MAGNITUDE FOR RANGE VARIATION AND THREE ORDERS OF MAGNITUDE FOR SCAN PATTERN VARIATIONS )N PRACTICE   D" INSTANTANEOUS DYNAMIC RANGE SOUNDS LIKE A MINI 
 00 0! ASS HF  &OR GA     THIS ARRAY CAN TOLERATE  0     OR  R!    D"  OR  RE   n .ATURALLY   EACH TYPE OF ERROR MUST BE ANTICIPATED  AND ONE MUST ALLOW A BUDGET FOR FAILED ELE 
 Silicon BJTs that operate in the HF through S-band frequency ranges are commonly  biased either Class-B or Class-C. Class-C operation is the preferred mode because  the RF output power of the amplifier is maximized for a given prime power input. In  general, the base-emitter junction is reverse-biased, and collector current is drawn for  less than half of an RF cycle. 
 Toobtainthetargetsizeorshaperequires resolution inrangeandinangle.Goodrange resolution isgenerally easiertoachievethancomparable resolution inangle.Insomeradar applications itispossible toutilizeresolution inthedoppler frequency shiftasasubstitute for resolution inangle,ifthereisrelativemotionbetween thedistributed targetandtheradar. Resolution ispossible sinceeachelement ofthedistributed targethasadifferent relative velocity. Thisprinciple hasbeenusedinsynthetic aperture radarsforgroundmapping, inverse SARforSOlandtheimaging ofplanets,andinthescatterometer formeasuring thegroundor seaechoasafunction ofincidence angle. 
 Clutter echoes may not always be present over the range at which detection is desired. The  clutter serves the same function as does the reference signal in the coherent MTI. If clutter  were not present, the desired targets would not be detected. 
 Wheeler, “Simple relations derived from a phased-array antenna made of an infinite current  sheet,” IEEE Trans ., vol. AP-13, pp. 506–514, July 1965. 
  
 5.2. Extended T arget Simulation The extended target simulations are carried out by using a 2000 ×2000 pixels real SAR image acquired from a P-band air-borne SAR system working at 600 MHz as is shown in Figure 13a. Since the observation geometry is redeﬁned in the beam projection and interpolation process of the ReBP algorithm, the geometry difference between two systems can be neglected in the simulation. 
 Singleton, H. E.: A Digital Electronic Correlator, Proc. IRE, vol. 
 TO 
 Broadcast., vol. 34, June 1988. 12. 
 For many purposes, the number of independent  samples is important because these  may be treated by using the elementary statistics of uncorrelated samples. For continu - ous integration, the effective number of independent sample is78 FIGURE   16. 10 Spectrum of fading from a homogeneous small patch   (a) before and ( b) after detection ch16.indd   17 12/19/07   4:55:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 {°£{  2!$!2 (!.$"//+  FILTER BANK 4HE ADVANTAGE OF PULSE COMPRESSION AFTER THE FILTER BANK IS THAT THE EFFECTS OF  DOPPLER ON PULSE COMPRESSION CAN BE LARGELY REMOVED BY TAILORING THE PULSE COMPRES 
  TO  
 When the scene is sparse and the measurement matrix satisﬁes the restricted isometry property (RIP) condition, Equation ( 2) can be solved via L1 regularization [ 18] minsi/bardblri−Φi·si/bardbl2 2+λ/bardblsi/bardbl1. (4) where λis the regularization parameter. For Equation ( 4), the optimality condition is 2ΦH i(Φisi−ri)+λp=0, (5) where (·)His the conjugate transpose and p=∂/bardblsi/bardbl1. 
 Installation ofAirborne Scanners.-In discussing antenna installations wewill treat first theairborne case. Here, one ofthepress- ingproblems isthechoice oflocation. The radar must have theunob- structed “vision” required foritsoperation, and itsantenna should beso installed that itmay behoused inanaerodynamically acceptable radome. 
 With these . FlG. 13.3 Comparison of X-band clutter data from different sources for a nominal wind speed of 15 kn. 
 Some of these technologies are briefly reviewed here. Antennas. The development of SBR is strongly dependent upon the technology of large space-deployable antennas. 
 [ CrossRef ] 28. Li, D.; Rodriguez-Cassola, M.; Prats-Iraola, P .; Wu, M.; Moreira, A. Reverse Backprojection Algorithm for the Accurate Generation of SAR Raw Data of Natural Scenes. 
 P.: Multibeam Planar Arrays, Proc. I £EE, vol. 56, pp. 
 V . N. Bringi and V . 
 The black tubular construction ofthe scanner yoke can beseen, together with the silver-plated +in. coaxial transmission line. The 29-in. 
 Now @depends, aswehave already seen, only onthe number ofcycles executed bythe stable local oscillator and thecoherent oscillator during theecho-t ime t1.Thus where wand warethe angular frequencies ofthe stable local oscillator and the coherent oscillator, respectively. The positive sign istobe taken when thelocal oscillator istuned below themagnetron frequency, thenegative sign when itisabove. Ifeither oscillator varies infrequency between pulses byanamount Au,thephase change produced isthen Ifthefrequency drifts atauniform rate, then where Tistherepetition period. 
 VELOCITY RATIO   6"2  COS COSCOSA YF     WHERE E IS THE DEPRESSION ANGLE OF THE ANTENNA CENTERLINE FROM THE HORIZONTAL &IGURE   SHOWS THE VARIATION OF THE NORMALIZED BORESIGHT 
 (n), andareplaced byk/a, weobtain,forS, S=PLahtanz 0, 4uh3(12) When O,issmall, asisusually thecase, itispermissible toreplace h/tan 00 byRti, themaximum range, which leads tothefinalr elation (13) The appearance ofXin this formula, which isto becontrasted with theresult obtained forthesimple fanbeam and point target, Eq. (5), can betraced totheinfluence ofthehorizontal beamwidth upon theeffective cross section ofthe extended target. Itwill beobserved that once the other system parameters, P,L!&,and a,ale specified, the quantity hR2isfixed. 
 IZE THE FILTER BEFORE USEFUL OUTPUTS MAY BE OBTAINED &OR EXAMPLE  WITH A THREE 
 There are many additional radome design issues and application specific consider - ations and design drivers, but these are beyond the scope of this chapter . ACKNOWLEDGMENTS The authors wish to acknowledge and thank Helmut Schrank, Gary Evans, and Daniel  Davis (also co-author of this chapter) for Chapter 6, “Reflector Antennas,” in the second  (1990) edition of this handbook.55 We are grateful for their contributions and portions of  the second edition chapter have been retained. Portions of the material in the “Radome” subsection were adapted from  Chapter 14,“Radomes,” in the first (1970) edition of this handbook,56 which was  authored by Vincent J. 
 SHIFT DELAYS AND SETTLING TIMES -OVING 4ARGET )NDICATION -4)  CAN BE USED WITH ANY OF THESE PULSE CHASING IMPLE 
 This iscalled amatching transformer. Or, ifaquarter-wave line isterminated byashort circuit, the input impedance isinfinite, i.e., equivalent toanopen circuit. Conversely, anopen-circuited quarter-wave line appears atthe input terminal tobe ashort circuit. 
 Skolnik, M. L: Fifty Years of Radar, Proc. IEEE, vol. 
 Therefore, these operations usually occur at RF or IF. Digital  compensation can be used if synchronous detection and analog to digital (A/D)  conversion are performed and the components are treated as complex phasors.  Furthermore, the operations must be linear until the sum signal and difference sig - nals have been processed by the hybrid amplifier. 
 Pluses and Minuses Denote  Relative Phases (+ and – Differ by 180 Degrees)  FIGURE 12. 28 Four-element monopulse feed with dum, delta az, and delta el ports ch12.indd   27 12/17/07   2:31:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Coherent complex image of the full scene. When using the sub-aperture method to obtain the RCS curves, we found that using 360 sub-apertures offered a good compromise between the azimuth resolution and the preciseness of the RCS amplitude. As shown in Figure 8, three pixels were selected to show the result of the RCS curve extraction. 
 W.: Millimeter Wave Research: Past, Present. and Future, 1\1/T Unco/11 Lah. Tl'cli. 
 MITTED SIGNALS OFTEN ARRIVE IN THE TARGET ZONE WITH A ROTATED AXIS OF POLARIZATION BUT STILL ESSENTIALLY LINEARLY POLARIZED 3INCE MANY TARGETS HAVE 2#3 THAT VARY WITH POLARIZATION  AN IMPORTANT RESULT IS THAT THE MOST FAVORABLE POLARIZATION WILL ILLU 
 The average, or root-mean-square (rms), sidelobe level is often more important.  For example, if 10% of the radiated power is in the sidelobes, the average sidelobe  level is −10 dB, where dB refers to the number of decibels by which the average  sidelobe level is below the gain of an isotropic (ideal) radiator. In theory, extremely  low sidelobes can be achieved with aperture illumination functions that are appro - priately tapered. 
 2.12 that rough surfaces like the ground can serve assatisfactory mirrors formore distant targets when theangle ofincidence issufficiently low. Because double-corner directivity depends onthe mirror-like properties ofahorizontal surface infront of vertical structures, weshould expect strongest signals from these struc- tures when they areseen from low angles. Many buildings orgroups of buildings return strong signals atlong ranges but tend tofade atshorter ranges when the higher angle ofincidence reduces their retrodirectivity. 
 J. V . Harrington, “An analysis of the detection of repeated signals in noise by binary integration,”  IRE Trans ., vol. 
 WAVEGUIDE HANDBOOK—MarCUrIitZ 11. TECHNIQUE OF?YIICROWAVE ME,4sumnmsw-Montgomery 12. MICROWAVE ANTENNA THEORY AND DEs~Gix-Siker 13. 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 25.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 Careful inspection of the decimator architecture reveals a potential problem with  the integrator. The input samples continually get added to the running sum, producing a  definite overflow condition. 
 When the wind is blowing away from the radar, the  receding-wave spectral line is the larger. When the wind 1s blowing perpendicular to  the direction of the radar beam, the two spectral lines are equal. Thus the relative magnitude  of the two major components of the doppler spectrum can provide a measure of the direction  of the wind. 
 n°Î{  2!$!2 (!.$"//+  5NEQUAL 4RANSMIT AND 2EFERENCE 7AVEFORM 3LOPES  ! STRETCH PROCESSOR WITH  UNEQUAL FREQUENCY 
 19Figure 1.14 - A basic radar system. 20The feedhorn at the upper extremity of the waveguide directs the transmitted energy towards the reﬂector, which focuses this energy into anarrowbeam.Anyreturningechoesarefocusedbythereﬂectoranddirectedtoward the feedhorn. The echoes pass through both the feedhorn andwaveguide enroute to the receiver. 
 This simple result means that  simple clutter models may be developed and used, although more complex models  may be necessary for some remote-sensing applications. FIGURE   16. 22 General characteristics of scattering coefficient variation  with angle of incidence ( after F . 
 B. Smith, and D. H. 
 TO 
 NANCES AT ODD MULTIPLES OF A HALF WAVELENGTH  WITH PLATEAUS OF NEARLY CONSTANT RETURN BETWEEN THE RESONANT PEAKS 4HESE PLATEAUS RISE WITH INCREASING DIPOLE LENGTH AND BECOME LESS DISTINCT AS THE DIPOLE BECOMES THICKER AND LONGER  4HEY EVENTUALLY DISAP 
 (13.18) is less for ice than for rain, and snowfall rates are generally less than rainfall rates.  Scattering from water-coated ice spheres. Moisture in the atmosphere at altitudes where the  temperature is below freezing takes the form of ice crystals, snow, or hail. 
 (2.27) reduces to Eq. (2.21), the probability-density  function for noise alone. Equation (2.27) is sometimes called the Rice probability-density  function. 
 Item 4, cosine-squared-plus-pedestal weighting, becomes equivalent, after normalization and use of a trigonometric identity, to the weighting function W1(J) of pair 3 in Table 10.7. The normalized ped- estal height H is related to the taper coefficient F1 by H = (1 - 2F1)/ (1 + 2F1). The Hamming function produces the lowest sidelobe level attain- able under category 4 of Table 10.8. 
 Douglas sea State Description Wave height h1/3ft Wind speed kts Fetch nmi Duration hr 1 Smooth 0 –10 –6 2 Slight 1 –36 –12 50 5 3 Moderate 3 –51 2 –15 120 20 4 Rough 5 –81 5 –20 150 23 5 Very Rough 8 –12 20 –25 200 25 6 High 12 –20 25 –30 300 27 7 Very high 20 –40 30 –50 500 30 8 Precipitous >40 >50 700 35Airborne Maritime Surveillance Radar, Volume 1 7-8. the subsequent signal processing. For these radars, the processing was essentially the non-coherent integration of Npulses through the action of the long-persistence phosphor in the radar PPI displays. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar.  AN INTRODUCTION AND OVERVIEW OF RADAR  1.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 X band (8 to 12.0 GHz). 
 D. R. Brunfeldt and F. 
 LosAngeles. Sept.14-17,1976,paper24/1. 23.Lipka.M.:PulseCompression FilterandWideband Receiver Evaluation. 
 FIG. 5.11 An integrated X-band transceiver module. (Photograph courtesy of Raytheon Company/Texas Instruments; development work sponsored by RADC, Griffiss Air Force Base,)Frequency L band* S band S band S/X bandt X bandPerformance characteristics Transmit mode RF power, W 11 10 2 2 2.5Gain, dB 35 31 23 30 30Efficiency, percent 30 16 22 25 15Gain, dB 30 25 27 22Receive mode Noise figure, dB 3.0 4.1 3.8 4.0 Performance sensitivities Parameter Gain sensitivity to drain voltage Phase sensitivity to drain voltagerms phase error Gain, dB 0.8 0.5 N.A. 
 IMPULSE 
 16.3. APractical MTI System.—Figure 169 isablock diagram ofa practical ,MTI system. Itcanberegarded asarefinement ofthearrange- ment ofFig. 
 [ CrossRef ] 14. Zhang, L.; Hu, M.; Wang, G.; Wang, H. Range-Dependent Map-Drift Algorithm for Focusing UAV SAR Imagery. 
 clutter residue ohscures part of the display. Hit is set too low there may be a" black  hole" effect on the display. The limiter provides a constant false alarm rate (CFAR) and is  essential to usable MTI performance.50  Unfortunately, nonlinear devices such as limiters have side-effects that can degrade  performance. 
 Bracalente, F. B. Beck, and W. 
 With a5-psec pulse, this limit for resolution becomes 820 ydplus the same additive constant. The intensity ofcloud return relative tosignal return from planes varies directly with pulse length (Sec. 3.10). 
 51 Hongmeng Chen, Zeyu Wang, Jing Liu, Xiaoli Yi, Hanwei Sun, Heqiang Mu, Ming Li and Yaobing Lu Knowledge-Aided Doppler Beam Sharpening Super-Resolution Imaging by Exploiting theSpatial Continuity Information Reprinted from: Sensors 2019 ,19, 1920, doi:10.3390/s19081920 .................... 69 Cataldo Guaragnella and Tiziana D’Orazio A Data-Driven Approach to SAR Data-FocusingReprinted from: Sensors 2019 ,19, 1649, doi:10.3390/s19071649 .................... 87 Andon Lazarov Pulsar Emissions, Signal Modeling and Passive ISAR Imaging Reprinted from: Sensors 2019 ,19, 3344, doi:10.3390/s19153344 .................... 
 Thayer: Models of Atmospheric Radio Refractive Index. Proc. I RE. 
 "  % !    
 Oct. 25 2U. 1977. 
 AZIMUTH  CELL IF THE NEW VALUE EXCEEDS THE AVERAGE BACKGROUND LEVEL BY A SPECIFIED AMOUNT !DAPTIVE 4HRESHOLDING  4HE BASIC ASSUMPTION OF THE ADAPTIVE THRESHOLDING TECH 
 If target returns are processed coherently, the phase of the LO signal  must be controlled such that each time it switches to a particular frequency, the phase of  the LO is the same phase that it would have been had no frequency switching occurred.  This requirement drives the architecture used to generate LO frequencies. Generating  all the frequencies from a single reference frequency does not guarantee phase coher - ence when frequency switching occurs. 
 2005 ,31, 122–131. [ CrossRef ] 10. Touzi, R.; Charbonneau, F. 
 This class of models is referred to as waveguide models. The use  of waveguide models dates back to the early 1900s when they were used to explain the  propagation of long wavelength radio waves around the surface of the Earth in a wave - guide formed by the Earth and the ionosphere. A description of waveguide models is  beyond the scope of this chapter but may be found in a publication by Budden.11 ch26.indd   15 12/15/07   4:53:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Whenthedoppler-shifted echosignalisknowntoliesomewhere withinarelatively wide bandoffrequencies, abankofnarrowband filters(Fig. 3.6) spacedthroughout thefrequency rangepermits ameasurement offrequency andimproves thesignal-to-noise ratio.The. CW AND FREQUENCY-MODULATED RADAR 77  Mixer -- -- El Ld-Eicx-[&k  Filler No. 
 M.: "Probability and Information Theory, with Applications to Radar," chap. 6,  McGraw-Hill Book Co., New York, 1953.  6. 
 IEEE T rans. Antennas Propag. 1997 ,45, 1664–1668. 
 ................................ .............................  13  External and Internal Losses  ................................ 
 PRIATE THEORETICAL BASISIE  THE hTHEORY OF THE EXPERIMENTv )F YOU GO TO SEA WITH A #7 RADARAN hAVERAGING WAVE SPECTROMETERvYOU WILL BE SELECTING A SPECTRAL LINE BY LONG INTEGRATION TIMES AND INTERPRET THE ORIGIN AS A WAVE EFFECT  NAMELY A h"RAGG RESONANCEv /N THE OTHER HAND  IF YOU USE A HIGH RESOLUTION PROBEA RADAR MICROSCOPETHE CLUTTER SCENE WILL BE POPULATED BY HIGHLY LOCALIZED SCATTER 
 32.Lyon,I.0.:Scan-Converted BrightDisplays forAirTrafficControl Systems, Conference onAir TrafficCOlllrol Systems Ellgineering andDesign,London, Mar.13-17,1967.lEEConference Publica­ tionno.28,pp.41-44. 33.O'Neal, N.V.,andP.M.Thiebaud: AScanConverter RadarDisplay System, NavalResearch Laboratory Memorandum Report2979,Washington, D.C.,January, 1975. .34.Robertson, J.W.,andF.J.Savill:RearPortDisplays: TheirAdvantages, Limitations, andDesign Problems forRadarApplications, International Conference onRadar-Present andFuture,Oct.23-25. 
   30!#% 
 Ifthe interference issevere, the higher peak powers and narrower bandwidths possible with ampli- 1This isusually accomplished bycombining grid modulation byboth the video and the pulse signals with plate modulation bypulses only.. SEC. 17.12] 30Q-MC/SEC A-MEQUIPMENT 71!3 tude modulation make itpreferable; if,onthe other hand, the interference isatlow level itcan bemore completely suppressed byfrequency-modulation methods. 
 BAND MONOPULSE PRECISION TRACKING RADAR INSTALLATION AT THE .!3!  7ALLOPS )SLAND 3TATION  6! )T HAS A  
  
 The British realized the advantages to be gained from the better angular  resolution possible at the microwave frequencies, especially for airborne and naval applica-  tions. They suggested that the United States undertake the development of a microwave A1  THENATURE OFRADAR11 aircraftradioaltimeter wasprobably thefirstcommercial application oftheradarprinciple. Thefirstequipments wereoperated inaircraftasearlyas1936andutilizedthesameprinciple ofoperation astheFM-CW radardescribed inSec.3.3.Inthecaseoftheradioaltimeter, the targetistheground. 
 xiii CONTRIBUTORS James J. Alter Naval Research Laboratory (CHAPTER 25) Stuart J. Anderson Australian Defense Science and Technology Organisation (CHAPTER 20) W. 
 Fluids , vol. 14, pp. 466–474, 1971. 
 II A summary of ASV Mk II given in [ 2] states that after three years of intensive research, development and war experience of airborne radar, there had been developed in ASV Mk. II an invaluable radar search device. As discussed in section 2.2.7, until the advent of the German radar warning receiver, the use of ASV had increased the number of daylight attacks against U-boats by 20%. 
 SHORT, SHARP SHOUTS 33  and back must be +%3:°°° miles, which is 372 miles. If we  halve that for the single journey we see that the aircraft  is 186 miles away from our station. It would be very  convenient if all radar calculations were as simple as  that! We shall find, however, if we go sufficiently deep  into radar mathematics, that the figures of the subject  become extremely involved, especially where we find  ourselves on the threshold of nuclear physics. 
 Sources of unwanted modulation are mechanical or acoustic vibration from fans and motors, power supply ripple, and spurious frequencies and noise generated in the stalo. In general, the tolerable phase deviation decreases with increasing modulation frequency because the doppler filter is less efficient in suppressing the effects. In a radar having two-pulse MTI, there is a linear relationship between the tolerable phase deviation and the period of the modulation. 
 This results from different path lengths through the dielectric material (different curvature) as well as local differences in thickness or dielectric constant. A constant error would present no difficulty, since the tracking and guidance loops are driving the boresight error (LOS rate) to zero. It is the variations of the radome error with gimbal angle—radome error slope—which cause the problem by creating a feed- back path. 
 Goodman, and R. M. Majewski, Spotlight Synthetic Aperture Radar ,  Norwood, MA: Artech House, 1995. 
 Similar to the RHi in which target height or altitude is  the vertical coordinate.  f'-Scope A rectangular display in which a target appears as a ceiltralizcd blip when the radar anterlna is  alnled at it. iiorizontal and vertical aiming errors are respectively indicated by the horizontal and  vertical displacement of the blip. 
 Allomorphic Forms. A binary code may be represented in any one of four allomorphic forms, all of which have the same correlation characteristics. These forms are the code itself, the inverted code (the code written in reverse order), the complemented code (Is changed to Os and Os to Is), and the inverted com- plemented code. 
 < 0°C)  z = 1600r2 for wet snow (ave temp.> 0°c) .J (13.26a)  (13.26b)  A lower surface temperature results in a lower value of the coefficient a. Still another value that  has been suggested is 77  z = 1000,1.6 ( 13.27)  There does not seem to be any agreed-upon value; the reader can take his pick. In all of the  above, the snowfall rate rat the ground is in millimeters per hour of water measured when the  snow is melted. 
 Ifweselect any column (w=constant) weobserve that the variation ofsignal power with nis something intermediate between 1/n and 1/fi. For large nand par- ticularly forwnot toosmall, thevariation isnot farfrom l/~~. This implies that doubling thenumber ofsweeps integrated, other things being equal, allows the signal power tobereduced byafactor l/~2. 
 Another problem istoknowwhengraceful degradation has gonetoofarandmaintenance isneeded. Thefulltestingofanarrayradarsystemisoftenmorecomplicated thanwithconven­ tionalradarsystems. Also,theincorporation ofIFFcanbemorecomplicated thanwith rotating antennas. 
 J. A,: Large Radomes, cliap. 5 of" Microwave Scaririing Antennas, vol. 
 J.  Roy. Meteor. 
 30.  1952.  113. 
 Willwerth, G. Meurer, L. Leibowitz, C. 
 32, pp. 1802–1814, December 1993. 43. 
 However, thecomplete absorber was arigid structure 2+in.thick, and it was never actually used. SEC.3.8] RET UliN FltOM 1W’O iSoTRoPl CTARGETS 73 When absorbent materials areapplied totargets whose cross section ismainly specula~, thecross section isreduced bythefactor \R\~—a result that isconfirmed byfield tests. The manner inwhich absorbent materials influence the diffraction cross section isshown inFig. 
 17  4 Information Content in Radar Signals ................................................................................ 19  4.1 Range ............................................................................................................................... 19  4.2 Velocity ........................................................................................................................... 
 294-297, July-October 1965. 23. Friedlander, A. 
 Figure 11: Calculation of height  . Radartutorial (www.radartutorial.eu)   9 Accuracy   Accuracy is the degree of conformance between the estimated or measured position and/or the  velocity of a platform at a given time and its true position or velocity. Radio naviga tion performance  accuracy is usually presented as a statistical measure of system error. 
 Long-term stability is typically character - ized by aging and environmental effects, specified in terms of frequency drift and  measured using an Allan Variance5 technique. Requirements are typically specified  in terms of an absolute frequency tolerance or a maximum frequency deviation over  some time interval. ch06.indd   14 12/17/07   2:03:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Acta Geod. Cartogr. Sin. 
 Pulse-limited space-based radar altimeters work  best over relatively mild topographic relief of mean slope zero, such as the ocean’s  surface. Over ice sheets or terrestrial surfaces, performance is degraded. Unwanted  characteristics include footprint dilation over rougher terrain, height errors in propor - tion to surface mean slope, and the tendency of the minimum range measurement to  hop from one elevated region to another (without the control or knowledge of the data  analyst). 
 ARRAYS 4HE CHOSEN WEIGHT IS A 4AYLOR TAPERING WITH  D" OF 03,2  4HERE ARE ONLY  DIGITAL DEGREES OF FREEDOM THIS MEANS THAT MARGINAL IMPROVEMENT OF PERFORMANCE IN TERMS OF 03,2 CAN BE ACHIEVED .EVERTHELESS  A 03,2 OF  D" WAS OBTAINED FOR THE COMBINATION OF  ANALOGUE WEIGHTS AND  DIGITAL WEIGHTS &OR THE SAME 5,! ABOUT  D" OF 03,2 WAS OBTAINED FOR THE DIFFERENCE CHANNEL #ONSIDERATIONS 2ELATED TO 3UB 
 ZONE IS CLEARLY SEEN IN ADDITION TO THE TARGETS FLIGHT PATTERN  ALLOWING THE OPERATOR TO SEE HOW THE PROBABILITY OF DETECTION OF THE TARGET WILL VARY WITH RANGE AND HEIGHT 7ITH THIS KNOWLEDGE  A DECISION ABOUT WHEN TO ATTEMPT AN ATTACK ON THE MISSILE CAN BE MADE &)'52%   !2%03 HEIGHT VERSUS RANGE COVERAGE FOR SURFACE 
 Marchais, and E. Normant, Air and Spaceborne Radar  Systems: An Introduction , Norwich, NY: William Andrew Publishing, 2001, pp. 329–335,  371–425, 171–176, 469. 
 Since only one main lobe is normally desired in real space, an appropriate de- sign will place all but one maximum in imaginary space for all angles of scan. With scanning, lobes that were originally in imaginary space may move into real space if the element spacing is greater than X/2. As the array is scanned away from broadside, each grating lobe (in sin 6 space) will move a distance equal to the sine of the angle of scan and in a direction determined by the plane of scan. 
 Thisis mostpronounced atthelowergrazingangles.Theeffectofpolarization on0'0alsodepends on thewind,asmentioned below. Variation withwind.!-4 Exceptatgrazing anglesnearnormal incidence, thevalueof0'0 increases withincreasing windspeed.Thebackscatter isquitelowwithwindslessthanabout 5knots,increases rapidlywithwindspeedsfromabout5toabout20knots,andincreases lessrapidlyathigherwindspeeds.! Anexample isshowninFig.13.4.3Thisisacomposite' plotofexperimental X-band dataobtained atthreedifferent locations andatthreedifferent timesforagrazing angleoftoO,(Thedatarepresented bythesolidcircleswereobtained intheBermuda area;thex'sintheNorthAtlantic; andthetriangles, off.puerto Rico.) Thedashedcurveineachfigureisdrawnasifallthreesetsofdatawerefromasingle population. Thiscurveisoftheformexp(-c/U)wherecisanarbitrary constant andUis thewindspeed.Whenallthreesetsofdataareconsidered asone,thedashedcurveshowsa saturation of0'0withwindspeedaboveabout20knots.However, conclusions drawnfrom viewingthethreesetsofdataasawholemaynotbefullyvalidbecause oftheaccuracy with - 20,------.---.,---,------.--...-----.---,-----r---,---,.,/ -30- -40iii "0 o b-50 -60_--e-----'-x-x- ..eJt x xx x -700=-----:5:-----:-10'::---:-'15=---2='0=-------:2::-'::5:------:3=-'=0:-------:3=-=5:---4:':0:---4:':5:-----='50 Windvelocity(knots) (0) - 20,----.,---.,---,---,---,-------.---.,-----,---,-,--, - --30f- -40 CD "0 t5'-50 -60- 66 X 66 6__----- ....-"---X-X---X-X-----X-- ....--. 
 BEAM SINGLE 
 CW Proximity Fuzes. The basic proximity fuze23'24 is a CW homodyne device whose only range sensitivity is in the rise of the doppler voltage signals as ground is approached or in the behavior of the signal when the antenna pattern intercepts an aircraft. Commonly a single element is used as both oscillator and mixer-detector. 
 SQUAR REDDISTRIBUTIONWITHDEGRESSOFFREEDOM    FOR3WERLING)6TARGETCHI 
 Banerjee, A.; Burlina, P .; Chellappa, R. Adaptive target detection in foliage-penetrating SAR images using alpha-stable models. IEEE T rans. 
 ALARM PROBABILITIES ALLOW TRACKS TO BE FORMED QUICKLY  (OWEVER  IF A LONGER DELAY IS TOLERABLE  THEN DETECTION THRESHOLDS CAN BE LOWER  RESULT 
 1Acoilusually consists ofatleast twoseparate windings symmetrically placed withrespect tothetube. They maybe connected either inseries orinparallel.. 478 THE RECEI VI.YG SYJSTEM-1.VDICA TORS [SEC. 
 7.30) or the JO-ft-diameter radome of AW ACS. The E-2C radome weighs just over  2000 lb. The entire unit rotates at a 6 rpm rate. 
 MERS   )N A RADAR RECEIVER  THE $ICKE 
 Stability Requirements. To achieve the theoretical clutter rejection and target detection and tracking performance of a pulse doppler system, the reference frequencies, timing signals, and signal-processing circuitry must be adequately stable.39"42 In most cases, the major concern is with short-term stability rather than long-term drift. Long-term stability mainly affects velocity or range accuracy or spurious signals (due to PRF harmonics) but is relatively . 
 Ulahy. F. T.. 
 Blake, L. V.: Prediction of Radar Range, chap. 2 of "Radar Handbook," M. 
 MATES  THE CONVERSION OF MEASURED REFLECTIVITY FACTOR TO RECEIVED ECHO POWER MUST BE WELL KNOWN 4HE GAINS OR CONVERSION CONSTANTS  OF THE VARIOUS RADAR COMPONENTS CAN BE MEASURED USING ENGINEERING TEST EQUIPMENT  MANUFACTURER SPECIFICATIONS  AND FIELD MEASUREMENTS #ALIBRATING WEATHER RADAR USUALLY MEANS TO ACCURATELY SPECIFY THE RADAR CONSTANT IN THE RADAR EQUATION AND TO ACCURATELY ESTIMATE THE RECEIVED POWER .   -%4%/2/,/')#!, 2!$!2   £°£ MEASURED BY THE RADAR SYSTEM )T ALSO ENCOMPASSES ITEMS SUCH AS KNOWING WHERE THE  SCATTERING VOLUME IS IN $ SPACE BY KNOWING ANTENNA POINTING ANGLES AND ACCURATELY DETERMINING RANGE !LTHOUGH FLOATING SPHERES  TETRAHEDRAL REFLECTORS  AND OTHER TARGETS OF KNOWN RADAR  CROSS SECTION MAY BE USED    THE IMPORTANT hSOLAR CALIBRATIONv TECHNIQUE USES THE  SOLAR POSITION TO ADJUST ANTENNA POINTING AND THE RADIATED SOLAR FLUX TO DETERMINE ANTENNA GAIN   !LONG WITH OTHER RADAR PARAMETER MEASUREMENTS  ONE CAN READ 
 7−8. See also  P. A. 
 J. Eccles and D. Atlas, “A dual-wavelength radar hail detector,”  J. 
 MALIZED HERE TO ALIGN WITH THE MEASUREMENTS AT A RANGE OF  KM )T IS CLEAR THAT  WITH THIS NORMALIZATION  THE PREDICTIONS MATCH REASONABLY WELL OVER THE WHOLE RANGE EXTENT  WITH SMALL BUT SYSTEMATIC DEPARTURES '27!6% SEEMS TO UNDERESTIMATE ATTENUATION SLIGHTLY AT  -(Z BUT OVER 
 S.: The Theory of Antenna Arrays," Microwave Scanning Antennas, vol. II," R. C. 
 Wider radar bandwidth, with appropriate  coding, forces the jammer to spread its energy over a wider band, thereby diluting the  effective jamming energy.3 ECCM design principles for main-beam noise jamming also apply to sidelobe  noise jamming, with the addition that the sidelobe response in the direction of the  jammer must be minimized. Ultralow sidelobes in the order of, say, 45 dB below  the antenna’s main-beam peak response are feasible by using advanced technology.  Sometimes the control of sidelobe noise jamming by using ultralow-sidelobe anten - nas is not proper; this is true because the main-beam width might be increased two  to three times. 
 The base circum- ference is 12.575X.. The heavy horizontal line indicates 10\2. (Courtesy of University of Michigan Radiation Laboratory.*}RELATIVE POWER (dB) . 
 Extraction is performed by an adaptive thresholding method that is similar to the one used in [ 32]. In this stage, the thresholding is performed on the original images to extract/label objects. The resulting two thresholded images are processed in two ways. 
 B., Jr., and W. L. Root: .. 
 All phase information is destroyed. It is  also possible to design a detector which utilizes only phase information for recognizing targets.  An example is one which counts the. 
 Figure 16.40150 illustrates how fast  this can be and also shows that the effect is much greater at the higher frequencies  where attenuation is greater. Figure 16.41151 shows the angular variation seen for  snow-covered ground. Off-vertical scattering is much greater at higher frequencies. 
 R. Pengelly, “Improving the linearity and efficiency of RF power amplifiers,” High Frequency  Electronics , September 2002. 20. 
 This explains why the operating condi- tions ofmagnetrons are not very critical with respect tothe magnetic field, anode voltage, orother quantities which might affect the velocity oftheelectrons, FIQ.10.14.—Space charge innonoscillating magnetron. Appreciable energy isassociated with the rOrotation. This motion takes place, however, inasubstantially constant r-ffield, since the RO rotation keeps the electron instep with the“variations ofthe r-ffield. 
 The factor-! appears before the integral  because the limits extend from -oo to + oo, whereas NO is defined as the noise power per cycle  of bandwidth over positive values only. Substituting Eqs. (10.8) and (10.9) into (10.7) and  assuming that the maximum value of !s0(t)l2 occurs at time t = ti, the ratio R1 becomes  R, -IL: S(f)H(f) exp (j2nji1) df 1  Nofoo IH(J)l2df  2 - 00  Schwartz's inequality states that if P and Q are two complex functions, then  f P* P dx J Q*Q dx ~ If P*Q dx 12  The equality sign applies when P = kQ, where k is a constant. 
 RADAR  SIMILAR TO A BACKSCATTER SOUNDER  THAT EMPLOYS A NARROWBAND WAVEFORM TO STUDY THE DOPPLER STRUCTURE OF THE ECHOES AS A FUNCTION OF GROUP RANGE FOR SELECTED FREQUENCIES IV  ! NETWORK OF REMOTE BEACONS OR TRANSPONDERS TO PROVIDE COORDINATE REGISTRATION V  3PECTRUM MONITORING RECEIVERS TO LOCATE CLEAR CHANNELS FOR POSSIBLE USE AND TO ASSESS THEIR PROPERTIES ! DETAILED DESCRIPTION OF THE SUITE OF AUXIL 
 By this point, it should be apparent that the application of radar absorbing materi - als to vulnerable targets is not a very effective way to enhance their survivability.  These materials are heavy, demand undue surface care and maintenance, suffer limited  bandwidth, and not least, are costly. A far more viable option, target shaping, is usually  available if one is willing to consider it at the onset of system development. 
 N.: "Radar System Engineering," MIT Radiation Laboratory Series, vol. 1, sec. 2.12,  McGraw-Hilt Book Company, New York, 1947. 
      
 NAL MOTION   THE PROCESSING TECHNIQUES USED TO ENHANCE TARGET DETECTION AND MAXIMIZE CLUT 
 The bandwidth can also be increased by  combining the best features of the klystron and the traveling wave tube to obtain better  bandwidth, efficiency, and gain flatness than either the conventional klystron or the  TWT. In these tubes, the basic structure is that of a klystron, but instead of a number  of single cavities being used, the single cavity is replaced by a more complex multiple  cavity. Three such variants are the Twystron,  extended interaction klystron,  and the  clustered cavity klystron . 
 The remaining equipment, apart from thenecessary power supplies, ismainly concerned with the display and measurement ofgeometrical quantities other than range.. 438 THE RECEIVING SYSTEM—RADAR RECEIVERS [SEC. 122 Since time isalways measured with respect totheinstant atwhich the modulator fires, synchronization between themodulator and thetimer is ofbasic importance. 
 SIDED BANDWIDTH ALWAYS TWICE THE ONE 
 [ CrossRef ][PubMed ] 6. Guaragnella, C.; D’Orazio, T. A Data-Driven Approach to SAR Data-Focusing. 
 J., R. S. Raven, and P. 
 5SThestandard deviation ofthedriftanglecan belessthan0.25°.Overwatertheaccuracies areslightlyworse.Thebackscatter energyover water,exceptfornearverticalincidence, isgenerally lessthanoverland,thuslowering the signal-to-noise ratio.Alsothereisanapparent increase intheangleofdepression sincethe rapidvariation ofseaecho(0"0)asafunction ofthedepression angleyfavorsreturnsfrom thelowerhalfoftheincident beam.Itresultsinthecenterofthedoppler spectrum being shifted,sothatthedirection asdetermined fromthedopplerspectrum willdifferfromthatof thecenteroftheantenna beam.Thisissometimes calledthecalibration-shift error.Thiserror canbecorrected bylobeswitching; thatis,byperiodically switching theantenna beamasmall amount inthey-direction atalowrate(perhaps 20HZ).55Twodisplaced doppler-frequency spectraareproduced atthetwoantenna positions, Anarrowtracking filtertracksthecross-] overofthetwospectra. Thefrequency ofthiscrossover isthesameforwaterasforland. Hence,therewillbenobiaserroroverwater.Averynarrowantenna beamwillalsoreducethe over-water biaserrorwithouttheneedforlobeswitching. 
 This information has been gleaned from the technical manuals of the time, the Air Publications, and many contemporaneous reports issued by TRE and the various RAF trials organisations. The radars developed inthe USA, also ﬂown by the RAF on American aircraft, and the radars developed for the RN Fleet Air Arm are also covered in the book, but in less detail. In a companion volume to this book I describe how this war-time work was continued in the UK with the development of airborne maritime surveillance radars for the RAF, up to the beginning of the twenty- ﬁrst century. 
 275. sensors Article Refocusing Moving Ship T argets in SAR Images Based on Fast Minimum EntropyPhase Compensation Xiangli Huang1,2, Kefeng Ji1,2,*, Xiangguang Leng2, Ganggang Dong3and Xiangwei Xing4 1State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System, National University of Defense Technology, Changsha 410073, China; huangxiangli_2008@126.com 2School of Electronic Science, National University of Defense Technology, Changsha 410073, China; luckight@163.com 3National Laboratory of Radar Signal Processing, Xidian University, Xi’an 710071, China; dongganggang@xidian.edu.cn 4Beijing Institute of Remote Sensing Information, Beijing 100192, China; xingxiangwei@nudt.edu.cn *Correspondence: jikefeng@nudt.edu.cn; Tel.: +86-731-8457-6384 Received: 15 January 2019; Accepted: 4 March 2019; Published: 7 March 2019/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: Moving ship targets appear blurred and defocused in synthetic aperture radar (SAR) images due to the translation motion during the coherent processing. Motion compensation is required for refocusing moving ship targets in SAR scenes. 
 —Radar wavesarereflected bytargets ofdifferent sizes regardless oftheir importance totheuser ofaradar set. The echo from anaircraft may belost inmuch larger echoes from near-by mountains, or itmay become tooweak tobefollowed toranges asgreat asdesired. The echo from afriendly aircraft islike that from ahostile one. 
 8.8 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 (matched filter processing); Curve C is for Taylor weighting with –40 dB peak time  sidelobe level ( n=6); and Curve B is for Hamming weighting where  W f Fmf B F( ) cos .= +   =1 2 2 042591 1π   (8.13) The Taylor coefficients for –40-dB Taylor weighting ( n=6) are listed here:5  F1 = 0.389116  F2 = −0.00945245  F3 = 0.00488172  F4 = −0.00161019  F5 = 0.000347037 Table 8.2 shows the peak time sidelobe level, 3-dB and 6-dB compressed-pulse  widths, and filter matching loss for the three weighting function types. The application  of –40-dB Taylor weighting reduces the peak time sidelobe level from –13.2 dB to   –40 dB and increases the filter matching loss from 0 dB to 1.15 dB. The 3-dB com - pressed-pulse mainlobe width increases from 0.886/ B to 1.25/ B when –40-dB Taylor  weighting is used. 
 AP-8, pp. 268-275, May, 1960.  I 12. 
 POLARIZATION  MEDIUM RESOLUTION 3CAN3!2  M AT  KM  DUAL 
 RMSE comparison on benchmarks (mm). BMK4 BMK5 RMSE Linear velocity model ±10.3 ±11.0 ±10.7 Rheological model ±3.4 ±6.5 ±5.0 245. Sensors 2019 ,19, 3073 6. 
 2ECEIVE /NLY ,0) ,OW 0ROBABILITY OF )NTERCEPT -"# -AIN "EAM #ANCELER -%- -AXIMUM %NTROPY -ETHOD -, -AXIMUM ,IKELIHOOD -4$ -OVING 4ARGET $ETECTOR -4) -OVING 4ARGET )NDICATOR. 
 TO 
 23.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 Furthermore, this approach is less costly and when exploiting noncooperative trans - mitters, more covert and less risky than using a dedicated transmitter. Consequently,  dedicated transmitters are not usually considered for these applications. Entries in the cooperative and noncooperative transmitter columns are called  hitchhikers when the transmitter is a monostatic radar. 
 WIND SPEED  TO  LOW SPEED  CROSS 
 (ANSEN  h#OMMENTS ON @#OEFFICIENTS FOR FEED 
 3.50  Clutter Map CFAR  .............................................  3.53  3.14 Diplex Operation  .....................................................  3.54  Benefits  ............................................................. 
 BEAM TUBES TO INTERACT WITH A MICROWAVE CIRCUIT TO PRODUCE AMPLIFICATION OF AN INPUT SIGNAL 4HE MAJOR DIFFERENCE AMONG THE SEVERAL TYPES OF LINEAR 
 The theory that follows isapplicable only tospecularly reflected radiation, and therefore tothespecular cross section. Absorbers ingeneral areoftwo types. Inthe first kind, reflections occurring atthe front surface oftheabsorber arecanceled bydestructive interference with the wave that enters the layer and subsequently reemerges. 
 FORM &&4  IS APPLIED TO THIS SET OF  . COMPLEX SAMPLES OF FREQUENCY 
 The CE mark may only be applied when the requirements of all other   relevant EU Directives, such as safety, have also been demonstrated. In the U.S.  the FCC web site30 provides current information and the limits are shown in  Figure 21.37.FIGURE 21.36  UWB SAR image of buried AT mines in the Yuma Desert, aircraft at 400 m altitude  (Courtesy SRI International USA, Dr. 
 The above has been concerned withrpropagation beyond the normal horizon. Within the  horizon, the refractive'effects of the 'duct can lead to a modification of the normal lobing  pattern caused by the interference of theldirect ray and the surface-reflected ray. The relative  phase between the direct and reflected rays can be different in the presence of the duct, and  454INTRODUCTION TORADAR SYSHMS heightandstrength oftheductwasfoundtovarywithwindspeed.Stronger windsgenerally resulted instronger signalsandlowerattenuation rates.Windspeedsfrom8to15knots produced alow,moderately strongduct,andwindsfrom20to30knolsproduct'd ahigher, butweakerduct.Passing squallsandrainshowers didnotwipeoultheductordecrease thepropagated signals. 
 SPECIFIC MODELS )N ADDITION  OTHER USERS IN THE (& SPECTRUM MUST BE OBSERVED CONTINUOUSLY AND OPERATING FREQUENCIES SELECTED TO AVOID INTERFERENCE 4HE ESSENTIAL FEATURES OF SKYWAVE PROPAGATION CAN BE SEEN IN &IGURE  4HE  IONOSPHERE  BEING AN IONIZED GAS WITH FREE ELECTRONS  WILL REFLECT ALL RADAR SIGNALS WHEN THE RADAR FREQUENCY IS LESS THAN THE PLASMA FREQUENCY GIVEN BY   F.0E r 
 Figure 6.13 shows how blockage can be virtually eliminatedPARABOLAFEED FIG. 6.11 Reflector shaping. VIEW FROM ELEVATION 0 . 
 This particular distribution is representative of clutter from a relatively large radar footprint (pulse length about 0.5 JJLS) measured at in- termediate grazing angles (20 to 70°) for moderate wind speeds (about 15 kn). It is Rayleigh-like but shows a tendency toward log-normal behavior for the larger cross sections. From a detailed statistical analysis of the NRL 4FR data, Valenzuela and Laing22 concluded that, for this data at least, the distributions of sea clutter cross sections were intermediate between the exponential (which is the power distribution corresponding to Rayleigh-distributed scattered-field am- plitudes) and log-normal distributions. 
 $&#  %   #!$$!# #!  '# %    '# #!%%!#           )& 
 Alternatively, the tracking radar might employ a multigate range-tracking  ch24.indd   41 12/19/07   6:00:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 ,. Singlefrequency-modulated pulse.Ambiguitic'i maybeavoided withasingle-pulse waveform ratherthanaperiodic-pulse waveform. Although theaccuracy ofsimultaneously measuring timeandfrequency withasimplepulse-modulated sinusoid wasseentobelimited,itis possible toobtainsimuItaneous timeandfrequency measurements toashighadegreeof accuracy asdesiredbytransmitting apuIselongenoughtosatisfythedesiredfrequency accuracy andonewithenoughbandwidth tosatisfythetimeaccuracy. 
 242 THE EMPLOYMENT OF RADAR DATA [SEC. 7.8 appears bright when thebeacon isbeing interrogated. Since thebeacon isinterrogated on!y when theradar ispointing atit, thebright line passes through the signal pip representing the individual plane carrying the equipment.. 
 When energy can pass through the surface, transmitted rays are bent toward the surface normal in crossing a surface into an electrically denser medium (higher index of refraction) and away from the surface normal into a less dense medium. This bending of rays is known as refraction. Depending on surface curvature and body material, reflected and transmitted rays may diverge from one another or they may converge toward each other. 
 Ê *  
 Let Wn represent weighting applied to Sn, and let <$>n represent the phase adjustment required for focusing. The operation of synthetic antenna generation then consists of taking the vec- tor sum of the signals Sn, adjusting their phases, and multiplying by weighting factors. The sum of this operation is given by 2SHe**nWH = focused pattern (21.62) In the case of unfocused synthetic antenna generation the phase adjustments <|>rt are not made. 
 One of the early radars combining 2D surveillance with height finding was the AN/CPS-6B, which utilized the V-beam principle. The V-beam radar consisted of a primary and a secondary antenna aperture mounted on the same rotating shaft. The primary aperture operated as a conventional 2D radar, generating a vertical cosecant-squared fan beam which provided detections and the range and azimuth coordinates of targets in the surveillance volume. 
 Neither ther-fhead northewaveguide ispressurized. The moisture problem intheturret issolved byelectric heaters which come onwhen- ever the radar shuts down. Only afew degrees rise above general atmosphere temperature prevents condensation. 
 K. Lee, C. Corson, and G. 
 POWER WIRELESS BASE 
 1500 1$+ Air!vays ..... 2500 ld Eclipse* .... 8401+Frequency, cps St]-le26volts 29volts fullload +load ]~123_l-A 410 410 1?121-1-.4 MO 410 10596 395 475 PU-16 390 403 MG- 153 340 395 PI?-21S-C 395 450 PB21S-D 395 440 IT-7 410 430 800-1-C 730 900Remarks LeeRegulator LeeRegulator Compound-wound Carbon-pile regu- lator Resonant Shunt-wound Shunt-wound Regulating field Compound-wound ●Nominal rated frequency 800 CDS. 
 Since the peak of the primary beam from a steered line source lies on a cone, the corresponding intercepts on the right and left corners of the top of reflector are farther out at/sec2 i|/0/2 tan 6. For this reason, the corners of a parabolic cylinder are seldom rounded in practice. Parabolic cylinders suffer from large blockage if they are symmetrical, and they are therefore often built offset. 
 TRACKING POINT WILL MOVE TO THE OTHER AIRCRAFT 4HE DWELL ON EACH TARGET WITH RANDOM SWITCHING BETWEEN THE TWO AIRCRAFT CAUSES THE DOUBLE 
 1200-1201, July 1959. 92. Siegel, K. 
 Barton, CW and Doppler Radars,   Section V-3, V ol. 7. Norwood, MA: Artech House, Inc., 1978, pp. 
 C. Oliver and S. Quegan, Understanding Synthetic Aperture Radar Images , Norwood, MA:  Artech House, 1998. 
 B. Wetzel, “A minimalist approach to sea backscatter—the wedge model,” in URSI Open  Symp. Wave Propagat.: Remote Sensing and Communication , University of New Hampshire,  Durham, preprint volume, July 28–August 1, 1986, pp. 
 FACTOR  MODEL PROPERLY IMPLEMENTS MULTIPATH PROPAGATION FOR OVER 
 AIR MISSILE 3!-  SYSTEMS -ONOPULSE 
 MODULATION DISTORTION WITHIN THE RECEIVER )F THE RECEIVER OPERATING BANDWIDTH IS A LARGE PERCENTAGE OF THE 2& FREQUENCY  SOME  FORM OF SWITCHED OR TUNABLE 2& FILTERING MAY BE REQUIRED SO THAT THE IMAGE RESPONSE IS REJECTED AS IT MOVES THROUGH THE OPERATING BANDWIDTH 4HE CHOICE BETWEEN USING SWITCHED OR TUNABLE FILTERING DEPENDS ON THE SWITCHING SPEED  LINEARITY  AND STABILITY REQUIREMENTS OF THE RECEIVER 3WITCHED FILTERS PROVIDE THE FASTEST RESPONSE TIME  WITH EXCELLENT LINEARITY AND STABILITY BUT CAN BE BULKY AND SUFFER FROM THE ADDITIONAL LOSS OF THE SWITCH COMPONENTS !N ALTERNATE APPROACH THAT IS SOMETIMES USED WITH LARGE OPERATING BANDWIDTHS IS  TO FIRST UPCONVERT THE INPUT 2& SIGNAL TO AN )& FREQUENCY HIGHER THAN THE 2& OPERATING BAND 4HIS PROCESS VIRTUALLY ELIMINATES THE IMAGE RESPONSE PROBLEM  ALLOWING THE USE OF A SINGLE 2& FILTER SPANNING THE ENTIRE OPERATING BANDWIDTH .ARROW BANDWIDTH FILTER 
 Such radomes can operate with high  t I ansmissiorl efficiency at almost all radar frequencies. Materials include single-ply neoprene-  coated terylene or nyloti fabric, Hypaloti-coated Dacron, and Teflon-coated fiberglass.  Inflation pressures are it] the vicinity of0.5 Ib/in2 gauge. 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°£ WHERE 3I IS THE AVERAGE BACKGROUND LEVEL   8I IS THE RETURN IN THE  ITH CELL  + IS THE FEED 
 When the MTI performance is limited by the antenna scanning fluctua­ tions, Shrader8 suggests letting V0c = 6 dB. (Although not stated by Shrader, it seems this  value is for a single pulse.) The improvement factor is the preferred measure of MTI radar  performance.  Still another term sometimes employed in MT[ radar is the interclutter visibility. 
 This  difference represents the average increase in signal-to-noise ratio required to obtain  the same probability of detection with eclipsing and straddle, as in the case where  the transmit pulse is received by a matched gate with no straddle. Since the detection  curve changes shape, the loss depends on the probability of detection selected, which  is depicted in Figure 4.21. For accurate results, eclipsing and range gate straddle loss  must be computed together. 
 8, p. 424, 1951. 56. 
 In general, the inﬂuence of the radar look direction, wind direction and wind speed on SAR eddy imaging will be analyzed from four aspects: (1) the brightness variation along eddy spirals and (2) the brightness variation of the SAR image, which can be directly distinguished from simulated images; (3) the visibility of eddy spirals and (4) the brightness contrast of the SAR image, which can be quantiﬁed using ΔσandΔσrrespectively. 4.1. Inﬂuence of Radar Look Direction During the simulations, the radar look directions are deﬁned as the angle counterclockwise from the xaxis of the current ﬁeld in degrees, and they were selected as 0◦,9 0◦, 180◦, and 270◦respectively. 
 TORTION INCLUDES ALL SPECTRAL COMPONENTS  EXCLUDING $# AND THE FUNDAMENTAL UP TO THE .YQUIST FREQUENCY 3).!$ IS A USEFUL FIGURE OF MERIT FOR !$ CONVERTERS  BUT IN DIGITAL RECEIVER APPLICATIONS  WHERE THE WORST SPURIOUS COMPONENTS MAY FALL OUTSIDE OF THE BANDWIDTH OF INTEREST  IT IS NOT NECESSARILY A KEY DISCRIMINATOR BETWEEN COMPETING CONVERTERS FOR A SPECIFIC APPLICATION %FFECTIVE .UMBER OF "ITS %./"   4HE TERM  EFFECTIVE NUMBER OF BITS  IS OFTEN USED  TO STATE THE TRUE PERFORMANCE OF AN !$ CONVERTER AND HAS BEEN STATED IN THE LITERATURE   IN TERMS OF 3).!$ AND 3.2  AS GIVEN BELOW #ONSEQUENTLY  IT IS IMPORTANT TO DIFFER 
 Combined Effects. Some idea of the complexity within a clutter scene due to other effects may be obtained from Fig. 13.19, which shows a digitized PPI dis- play of clutter in the Sargasso Sea, under light wind conditions and near a thermal oceanic front.71 Although all possible contributing effects were not identified, ob- servers noted the presence of human-made detritus organized by the currents at the edges of the thermal front, slicks probably of both natural and artificial origin, fronds of seaweed close to the surface, and the presence of light and variable winds. 
 A.:" Electromagnetic Theory," McGraw-Hill Book Company, New York. 1941.  5. 
 ITY CHARACTERISTICS 4HE DIFFERENTIAL REFLECTIVITY BETWEEN THE HORIZONTAL AND VERTI 
 25Range Gates • Typical pulse train and range gates • Analog implementation of range gates     L123 M   L123 M  L123 M  L123 M  LDWELL TIME =N/PRF M  RANGE GATESt TRANSMIT PULSES RECEIVER.   M   M..... ..... 
 '+ ," $*#%$%)** ($      $ #(!) -  (   #. 
 The relative gain is also called the aperture efficiency [Eq. (7.9)].  The aperture efficiency times the physical area of the aperture is the effective aperture. 
 oneforeachbeam.Thiscanrepresent anexpensive trade.Ifinsteadofonereceiver perbeam.onlyoneorafewreceivers aretime-shared overthetotalcoverage, someformor switchingisrequired.rftherequirements forswitching speedandflexibilityaresimilartothose ofaconventional electronically steered phased-array radar,theproblem ofswitching a receiver between portsofthebeam-forIlling arraymaybeasdifficult asthatofproviding the phaseshifting inaconventional arrayradar.los Inprinciple, asurveillance radarwithafixedtransmitting beamofwidth0/andanumber Noffixed,narrow receiving beamsofwidthOrcovering thesamevolume(NOr=0,),has performance equivalent toaradarwithasinglescanning transmit-receive beamofwidthOr' provided thecomparison ismadeonasimilarbasisandthereceived signalsareprocessed in theoptimum manner ineachcase.Thetransmit antenna gaininthemultiple-beam systemis IINththatofthescanning single-beam system.Thereduction oftransmit antenna gainina multiple-beam radariscompensated, however, intheidealcasebytheincreased number of hitsavailable forintegration. Thegainofthetransmitting antenna inthemultiple-beam systemisOrlO,=IINthatofthetransmitting gainofthescanning-beam antenna. Thusthe signal-to-noise ratioperpulseofthemultiple-beam radarislessthanthesignal-to-noise ratio ofthescanning-beam radar.IftheseNpulsesareintegrated without lossasinaperfect predetection integrator, thetotalsignal-to-noise ratiointhemultiple-beam radarjustcompen­ satesforthelessertransmit gain.Thusthemultiple-beam ffidarandthescanning-beam radar haveequivalent detection capability, provided thedataratesarethesameandintegration is without loss.Datarateisdefinedhereastherevisittimeinascanning-beam radar,andina multiple-beam radaritisthetimeoverwhichthetotalnumber ofpulsesareintegrated. 
 131. Green, T. J.: The Influence of Masts on Ship-Borne Radar Performance, RADAR-77, Oct. 
 BER OF RECEIVERS IN THE $"& ARRAY  )F ADAPTIVE BEAMFORMING IS IMPLEMENTED USING  DIGITAL BEAMFORMING  ELEMENT 
 17.3 and 17.4, target detectability is limited only by thermal noise, independently of radar alti- tude, speed, and sidelobe level. This requires system stability sidebands to be well below noise for the worst-case main-beam clutter. Thus, although medium PRF provides all-aspect target coverage, the target is potentially competing with sidelobe clutter at all aspects, whereas with high PRF a target can become clear of sidelobe clutter at aspect angles forward of the beam aspect. 
 Two-coordinate angle information is obtained by scanning the beams about the bore-  sight axis similar to the extraction of azimuth and elevation angle information in the conical-  scan tracker. Amplitude fluctuations of the target echo signal do not in principle degrade the  tracking accuracy as in the conical-scan tracker because a difference signal is extracted from  the simultaneous outputs of the two squinted beams. However, the need to scan the two beams  means that a single pulse angle-estimate is not obtained as in a true monopulse. 
 E.: "Radar Design Principles," McGraw-Hill Book Co., New York, 1969.  34. Rihaczek, A. 
 117.Hlcvis.R.c.:LossesDuetoRainonRadomes andAntenna Reflecting Surfaces, IEEETrailS., vol.AP-I\rr175176.January. 1965. llHRUIl·.J.C:Mort:onWetRadollles, IEEE'{'railS.,vol.AP-IJ.pp.X23X24,Septcmhcr, 1965. 
   PP n    2 "ERNARD  - % &REZAL  $ 6IDAL 
 A.: "Instruments of Darkness," Charles Scribner's Sons, New York. 1977.  8. 
 The unsteady motions of the platform can cause errors in the angular measurement' and  distortion of the data on indicators like the PPI. Corrections can be applied in some cases to  account for these distortions. This is called data stabilization. 
 As the frequency is changed, the phase across the aperture tilts linearly, and the  beam is scanned. Frequency-scanning arrays are relatively simple and inexpensive   FIGURE 13.2  Generation of scanned beams: ( a) phased array, ( b) time-delay array, ( c) frequency-scanned  array, and ( d ) Blass-type array ch13.indd   7 12/17/07   2:38:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
       )0    WHERE 0F D"M    POWER OF INPUT SIGNAL AT FREQUENCY F IN D"M  0F D"M    POWER OF INPUT SIGNAL AT FREQUENCY F IN D"M  0)0D"M    THIRD ORDER INTERCEPT POINT IN D"M )NTERMODULATION CAN RESULT IN A VARIETY OF UNDESIRABLE EFFECTS SUCH AS L )NTERMODULATION OF CLUTTER RETURNS CAUSING BROADENING OF CLUTTER DOPPLER WIDTH   RESULTING IN THE MASKING OF TARGETS L 5NWANTED IN 
 The picture soobtained would, ineffect, bedivided into anumber of elements equal tothe ratio ofthe total solid angle scanned tothe solid angle included inthebeam itself. Thus thenumber ofpieces ofinforma- tion that the system can collect per second issimply the number of picture elements multiplied bythenumber ofcomplete scans persecond, exactly asintelevision. Inthe radar system giving hemispherical coverage which was used asanexample inthe preceding section, this number comes to1500 elements persecond, which isnotvery impressive bytelevision standards. 
 S. Berkowitz (ed.), New York: John Wiley & Sons, 1965, chap. 7, p. 
 STATE TRANSMITTERS CONSIST OF AMPLIFIER MODULES THAT FEED EITHER ROWS  COLUMNS  OR SINGLE ELEMENTS OF AN ARRAY ANTENNA %SPECIALLY IN THE LAST 
 They areswitched by the same flip-flop (rectangular-wave generator) that controls the saw- tooth generator and arethus closed during the entire interval between. SEC. 13.16] RESOLVED TIMEBASE 537 ‘“’’*”’’” mi?vh,v%~ i%?. 
 S. O. Rice, “Reflection of electromagnetic waves from slightly rough surfaces,” in Theory   of Electromagnetic Waves,  M. 
 PROTECTION  30  DECOY JAMMING IS AN OFF 
 DANCE WITH NATIONAL AND INTERNATIONAL REQUIREMENTS 5SERS SHOULD CONSULT WITH THEIR NATIONAL AUTHORITIES TO DETERMINE THE REGULATORY ENVIRONMENT 7ITHIN THE %UROPEAN 5NION %5   THERE ARE TWO MAIN CONSIDERATIONS GOVERN 
 Hajovsky. R. (3.. 
 J., and D. V. Morgan (eds.): "Microwave Devices," John Wiley & Sons, New York, 1976. 
 TEM GAIN FACTOR RADOME  WAVEGUIDE  ROTARY JOINTS  ETC  SINCE ALL THE MEASUREMENTS  MUST BE REFERENCED TO THE SAME POINT IN THE RADAR SYSTEMUSUALLY AT A COUPLER NEAR THE CIRCULATOR "ECAUSE THE ANTENNA GAIN IS NOT UNIFORM OVER THE BEAMWIDTH  ASSUMING A UNIFORM GAIN CAN LEAD TO ERRORS IN THE CALCULATION OF  : 5SING A SIMILAR DERIVATION   0ROBERT 
 9. Sanders, W. K.: Post-war Developments in Continuous-wave and Frequency-modulated Radar, f RE  Trans., vol. 
 14.11 minimum oftwo hours per month atfull load. For such emergency service asthat outlined, gasoline-powered prime movers arereliable and satisfactory. Voltage Stability ofSupply.—If the service isobtained from asource unstable involtage, Iocalvoltage stabilization must reemployed. 
 As a result, it is not necessary to implement multiple matched filters to  cover the range of expected target doppler shifts. LFM Waveform Definition.  The LFM waveform is a single-pulse bandpass signal  defined as  x(t) = A rect ( t/T) cos [2p  f0 t + pa t2] (8.1) where T is the pulsewidth,  f0 is the carrier frequency, a  is the LFM slope, and the rect  function is defined as  rect( )xx x=< >  1 1 2 0 1 2, || / , || / (8.2) The LFM slope is given by a = ± B/T, where the plus sign applies for a positive  LFM slope (termed an up-chirp ) and the minus sign for a negative LFM slope (a down- chirp ). 
 15.14  15.6 Optimum Design of Clutter Filters  ...........................  15.16  15.7 MTI Clutter Filter Design  .........................................  15.23  15.8 Clutter Filter Bank Design  ....................................... 
 UNITS PER KILOMETER  OR BETWEEN  AND  - 
 In contrast to Ku band, the C band data  were less degraded by rain and proved to be more reliable for higher wind speeds.119  The antenna swaths spanned 500 km, from which the averaged data from the three-look  directions were colocated into 50-km resolution cells, posted on a 25-km grid. ASCAT , the Advanced Scatterometer135 aboard MetOp-1, is essentially an improved  version of the ERS-1/2 instruments. It is a stand-alone radar designed for operational  use; it does not have to time-share onboard electronics as was the case with the scat - terometer in the AMI suite. 
 The applicability of these particular tests to the usual  PPI display can be questioned since a 5-inch-diameter CRT was used with simulated echoes  placed at an azimuth unknown to the operator at a distance of 1 inch from the center of the  scope. The conclusion that might be drawn from such experiments is that somewhat less than  theoretical integration improvement will be obtained if the pulses are not displayed properly;  that is, the persistence of the display should be sufficient to prevent excessive "loss of  memory," the dynamic range of the display must be large enough not to lose signal informa-  tion, and the display resolution should be consistent with the radar resolution to avoid  collapsing loss. Since the dynamic range of most displays is limited to a relatively small valus,  the pulses received from a target should be displayed side by side (as is usually the case on a  PPI or B-sbpe) rather than piled up at a single point on the display. 
 25.Weil.T.1\.:SurveyofRaytheon PulsedRadarTransmillers, Electronic Progress, vol.17,no.2. pp.1424,Summer. 1975. 
 02& CENTRAL 02& SELECTION EXAMPLE &)'52%  %XAMPLE 2'(02& ECLIPSING AND STRADDLE NEAR MAXIMUM RANGE . x°Óä  2!$!2 (!.$"//+  &OR EXAMPLE  THE THRESHOLD SCHEME MIGHT BE  D" 3.2 PER 02) AND  OUT OF   FOR ALL 02)S /FTEN MULTIPLE AND DIFFERENT THRESHOLDS ARE USED FOR EACH #0) AND 02)  ,OWER THRESHOLDS ARE ALLOWABLE FOR HIGHER NUMBERS OF TOTAL HITS )T SHOULD BE NOTED  THAT ECLIPSING AND STRADDLING  AND SO ON  HAVE MUCH LESS EFFECT AT CLOSER RANGES WHERE THERE IS USUALLY MORE THAN ENOUGH 3.2 !NOTHER SERENDIPITOUS EFFECT OF THIS SELECTION TECHNIQUE IS THAT AS AN INDIVIDUAL 02) RANGE CLEAR REGION GETS SMALLER  THE DOPPLER CLEAR REGION GETS LARGER  FILLING 
 NOMENA  AND THEY ARE EACH SIGNIFICANT TO DIFFERENT FUNCTIONS OF THE RADAR ,OW 
 Dax, P. R.: Keep Track of that Low-Flying Attack, Microwuues, vol. 15, pp. 
  
 Automatic Frequency Control.-Radar automatic frequency control (AFC) isascheme inwhich the difference infrequerwy between themagnetron and thelocal oscillator iscompared inadiscriminator cir- IInanexact calculation, account must betaken ofthedifference intheimpedance ofthevarious branches atsignal andlocal-oscillator frequencies. Asismentioned inthenext paragraph, thisisconsiderable forthehighly resonant TRcavity. QUali- tatively, however, thereciprocity yargument isvalid. 
 Sin. 1996 ,24, 74–79. 14. 
 45. Martindale, J.P. A.: Lens Aerials at Centimetric Wavelengths, J. 
 I~crkclcy, 1964.  54. Peeler. 
 However, transmitting tubes are not all uniform  in quality, nor should it be expected that any individual tube will remain at the same level of  performance throughout its useful life. Also the power is usually not uniform over the operat­ ing band of the device. Thus, for one reason or another, the transmitted power may be other  than the design value. 
 Thus a small antenna requires a large transmitter power. Since large power  is not easy to achieve at millimeter wavelengths, it is not likely that radars in this portion of the  spectrum will find wide application for long-range surveillance.  The characteristic wavelengths of the millimeter region are responsive to individual scat-  terers of size comparable to the wavelength. 
 The heading  of the aircraft, as might be obtained from a compass, must also be known for proper naviga­ tion. The vertical reference may be used either to stabilize the antenna beam system so as to  align it with the horizontal, or alternatively, the antennas might be fixed relative to the aircraft  and the ground velocity components calculated with a computer.  A practical form of doppler-navigation radar might have four beams oriented as in  Fig. 
 Its response is e~uivalent to a triple canceler consisting  of a cascade of three single-delay-line cancelers. (Note the potentially confusing nomenclature.  A cascade configuration of three delay lines, each con.nected as a single canceler, is called  a triple canceler, but when connected as. 
 49,  pp. 24–46, January 2006. 113. 
 IRE, vol. 36,  pp. 18CL 196. 
 The general Idea onwhich this calculation isbased isasfollows: Ifthe system scans atauniform rate, the system output signal asa function oftime asitscans across afixed target depends onthedirectivity asafunction ofangle. The frequency spectrum isthen the Fourier transform ofthe directivity function. But this directivity depends ontheillumination ofthedish and isinfact theFourier transform ofthe illumination asafunction ofdistance across the dish. 
 46 to 9.47 nth-time-around tracking, 9.24 on-axis tracking, 9.25 to 9.26 range tracking in, 9. 21 to 9.24 sequential lobing, 9.16 to 9.17 servosystems for, 9.17 to 9.19 sources of error in, 9.26 updating tracks, 7.26 to 7.30 TRAKX, dual band monopulse radar, 9.24 Transmit/receive module characteristics, 11.29 to 11.31 Transmit signal digital processing, 25. 20 to 25.22 Transmitter-related ECCM, 24.31 to 23.32 Transmitters, 1.2, 1.4 clustered-cavity klystrons, 10.12 to 10.13 constant efficiency amplifier, 10.21 to 10.22, 10.26 crossed-field amplifiers (CFA), 10.16 to 10.17 extended interaction klystron (EIK), 10.11 grid-controlled tubes, 10.21 to 10.23, 10.25 g yrotrons, 10.17 to 10.19, 10.26 for HF OTH radar, 20. 
 Series vs. parallel feeds. ?'he relative phase shift between adjacent elements of the array must  be d, = 2n(tl/A) sin 0, in order to position the main beam of the radiation pattern at an angle  0,. 
 Thewaveform maybegenerated bya number ofmeansincluding avoltage-controlled oscillator whosefrequency ismadetovary. 424 INTRODUCTION TO RADAR SYSTEMS  with an applied voltage; the so-called serrasoiti motii~lator'~ which generates a qilatlratic  waveform and compares this with a repetitive sawtooth wave to generate pulses that have a t2  variation in spacing which are filtered to form a linear-FM waveform; a tapped delay-line with  nonuniform tap spacings determined by the positive-going zero crossings of the desired linear-  FM waveform, followed by a filter to form the output waveform; a synthesizer1' which  combines a staircase frequency waveform with the average desired slope, and a sawtooth  frequency waveform which fills-in the steps with a short linear FM; or by digital means in  which an algorithm performs a double integration to produce a phase at the output of the  generator which varies as the square of time, as required for a linear FM.I8 The digital  generator has the advantage of flexibility in the selection of bandwidth and time duration, as  well as good stability and low residual generation errors. The above are sometimes called  actiue methods for generating waveforms. 
 Improvement bythis factor of10would increase the range ofaradar setonly bythe factor 1.8; and further receiver improvement can today bewon only by themost painstaking and difficult attention todetails ofdesign. WhyMicrowave s?-The reader will have observed that when radar is discussed inwhat has gone before, microwave radar isassumed. This is true ofthe balance ofthis book aswell. 
 FLYING AIRCRAFT  THEY CANNOT ELEVATE THEIR ANTENNA BEAM TO ELIMINATE THE CLUTTER 4HESE CONSIDERATIONS HAVE LED TO THE DEVELOPMENT OF AIRBORNE -4) !-4)     RADAR SYSTEMS SIMILAR TO THOSE USED IN  SURFACE RADARS  n DISCUSSED IN THE PRECEDING CHAPTER 4HE MISSION REQUIREMENTS FOR AN !%7 RADAR DRIVE THE NEED FOR  AZIMUTHAL COV 
 Williams: Circular Polarization in Radars, Rudio i111d Elrctro~ric  Engineer, vol. 47, no. 1/2, pp. 
 7.7 Ten-element linear array scanned to 60°. Element spacing s = X/2.ELEMENT FACTOR E6 (6) = /cos8 ARRAY FACTOR _ ... sin 57r(sin 6-0.866)ta »"/ z 'IO sini( sine-0.866) PATTERN E(6) = E0(O) x Ee.C6)RELATIVE FIELD STRENGTH . 
 (The sign of the doppler may  be determined in the video by other means, as described later.) One advantage of the foldover  in the video is that only half the number of filters are required than in the IF filter bank. The  equivalent of a bank of contiguous bandpass filters may also be obtained by converting the  analog If or video signal to a set of sampled, quantized signals which are processed with  digital circuitry by means of the fast Fourier transform algorithm.16  A hank of overlapping doppler filters. whether in the IF or video, increases the complexity  f the receiver. 
 The ﬂow chart of the calculation process is shown in Figure 9. Sequence Rgstores the ground range corresponding to each DEM data in the sequence DEMs . 3. 
 F, no. 5,   pp. 303–308, October 1993. 
 Whenthereceiver videooutputisfirst processed byanautomatic detector orautomatic detection andtracking processor (ADT),the outputdisplayed issometimes calledsynthetic video. Thecathode-ray tube(CRT)hasbeenalmostuniversally usedastheradardisplay.There aretwobasiccathode-ray tubedisplays. Oneisthedeflection-modulated CRT,suchasthe A-scope. 
 Ingenerai, theplate and screen voltage should below (75to120volts arecommon) and the cathode current should beashigh asispermitted bythetube ratings. The noise figure that can beobtained byuse ofthe circuit shown in Fig. 12.4 depends upon the intermediate frequency and the over-all receiver bandwidth. 
 It can be of a shape and size most suited for satisfying the average  or peak power requirements without regard for conducting RF currents, since none arc  present.  The design flexibility available with the klystron is not present in other tuhe types con­ sidered in this chapter, except for the traveling-wave tuhe. In most other tubes the functions of  electron emission, RF interaction, and collection of electrons usually occur in the same region. 
 Walt Hausz of the General Electric Company, and J. Koehler, at that time with Philco Corporation. Subsequently, it came to the author's attention that Carl Wiley and the Goodyear Aircraft Company had already undertaken some work and had made substantial progress in the synthetic-antenna area. 
 CAVITY KLYSTRON AMPLIFIER  
 Winter, M. J. Schlangen, and C. 
 This occurs for flat and singly curved surfaces. Physical Optics.  The theory of physical optics (PO) is a suitable alternative  for bodies with flat and singly curved surface features. 
 Baker, J. J. Douglass, and A. 
 Tsuda, M. Yamamato, T. Sato, and S. 
 (25.8) is less than 10 percent for 0° < 6^ < 180° and L > 4.6 ckTrt. Other target location techniques are possible.16'18 The transmitter beam- pointing angle 0r can be used in place of QR. Unless the transmitter is also a monostatic radar tracking the target, target location accuracy is degraded, since beam splitting is sacrificed. 
 £n°{ä  2!$!2 (!.$"//+  RANGE DELAY COARSE AND FINE VALUES  CORRECTED BY THE REMAINING HEIGHT ERROR MEASURED  FROM THE WAVEFORMS POSITION IN THE TRACKER 3URFACE WIND SPEED AND SIGNIFICANT WAVE HEIGHT  ARE DERIVED FROM THE !'# VALUES AND THE WAVEFORMS SHAPE  RESPECTIVELY 4HE PRECISION OF AN INDIVIDUAL HEIGHT MEASUREMENT IS DETERMINED BY THE COMBINATION  OF RANGE RESOLUTION AND INCOHERENT WAVEFORM AVERAGING )F A SINGLE SIMPLE SHORT PULSE WERE TRANSMITTED  THEN THE HEIGHT RESOLUTION WOULD EQUAL THE PULSE LENGTH 4HE PRINCIPAL DISADVANTAGE OF A SHORT PULSE IS THAT IT CONTAINS LITTLE ENERGY 4HE INHERENT RESOLUTION OF A PULSE IS INVERSELY PROPORTIONAL TO ITS BANDWIDTH 3PACE 
 A range of only a few decibels of pulse shaping is feasible with a magnetron, and even then frequency pushing may prevent obtaining the desired benefits. 6. If lowest possible spurious power levels are required. 
 There­ fore. when additional isolation is necessary, as in the high-power CW tracker-illuminator, a  dynamic canceler can he used that senses the proper phase and amplitude required of the  nulling signal. 5• 13 Dynamic cancelation of the leakage by this type of" feed through nulling"  can exceed .10 dB.·"  The transmitter signal is never a pure CW waveform. 
 RESOLUTION MODE !  
     PP n  !PRIL    0 3WERLING  h0ROBABILITY OF DETECTION FOR FLUCTUATING TARGETS v  )2% 4RANS  VOL )4 
 -*" - 
 Daley, J. T. Ransone, J. 
 Querido. H.J., J. Frank, and T. 
 Power droop , pulse  top amplitude , and overshoot are also of interest. ELINT  experts sometimes scrutinize these characteristics, as they  provide additi onal information about a radar's characteristics .  . 
 Thesizeofthesmallgate wouldbedetermined bytheaccuracy ofthetrack.Whenatargetdoesnotappearinthesmall gate,alargergatewouldbeusedwhosesearchareaisdetermined bythemaximum accelera­ tionexpected ofthetargetduringturns. Onthebasisofthepastdetections thetrack-while-scan radarmustmakeasmoothed estimate ofatarget'spresentpositionandvelocity, aswellasapredicted position andvelocity. Onemethodforcomputing thisinformation istheso-called ex-fJtracker(alsocalledtheg-II tracker84),whichcomputes thepresentsmoothed targetposition\xnandvelocityIbytht: following equations 72 ' Smoothed position:xn=xpn+ex(xn-xpn) Smoothed velocity:xn=xn-1+~(xn-xpn)(5.8) (5.9) wherexpn=predicted positionofthetargetatthenthscan,Xn=measured positionatthenth scan,ex=position smoothing parameter, fJ=velocity smoothing parameter, andTs=time between observations. 
 It  is possible, however, with a suitable transmitted waveform to employ a single matched filter  that will accept doppler-shifted echoes with minimum degradation.  It has been shown that the waveform which allows a single pulse-compression filter to be  rnatched for all doppler-frequency sfiifts (all target velocities) isZcZ8  The arriplitude A(t) of Eq. (1 1.55) represents modulation by a rectangular pulse of width T. 
   PP n    2 + -OORE ET AL  h3IMULTANEOUS ACTIVE AND PASSIVE MICROWAVE RESPONSE OF THE %ARTHTHE  3KYLAB 2!$3#!4 EXPERIMENT v IN  0ROC .INTH )NT 3YMP  2EMOTE 3ENSING %NVIRON   5NIVERSITY  OF -ICHIGAN  !NN !RBOR    PP n  2EF  3EE SUMMARIES IN VOL ))  CHAP   AND VOL )))  CHAP   & 4 5LABY  h6EGETATION CLUTTER MODEL v )%%% 4RANS  VOL !0 
 (/2):/. 2!$!2   Óä°È THE PREDICTED DISTRIBUTION OF THE RESULTANT RADAR CROSS SECTION WHEN MULTIPATH AND  &ARADAY ROTATION ARE TAKEN INTO ACCOUNT 4HE RELEVANT PHYSICSROUGH SURFACE FORWARD SCATTERING COEFFICIENT  BISTATIC IN THE VERTICAL PLANE  FREE 
 (:l/ic7r Trrttrk cz~rd (;rorgc.' 2,  custorrlary way based on gaussian noise. To avoid false alarms, the threshold detector at the  output of such a teceiver must be set to a higher value than when the clutter is Rayleigh.  The increased threshold needed to avoid false alarms is significant (10 to 20 dB, or more, in  some cases). 
 Another  consideration is that the 12-horn feed is not  practical for focal-point-fed parabolas or  reflectarrays because of its size. A focal- point feed is usually small to produce a  broad pattern and must be compact to avoid  blockage of the antenna aperture. In some  cases, the small optimum size required is  below waveguide cutoff, and dielectric  loading of the horn apertures becomes nec - essary to avoid cutoff. 
 Typically, the beam can be switched in several microseconds, but it can be considerably  shorter j.f desired.  M ultip/e, independent beams. A single aperture can generate many simultaneous independent  beams. 
 !RRAY 3YSTEMS  AND 4ECHNOLOGY  "OSTON 53!   /CTOBER n    PP n  ! 2 -OORE  $ - 3ALTER  AND 7 + 3TAFFORD  h-%3!2 -ULTI 
 STATE DEVICES WITH A HIGH DUTY 
 0ERTURBATION AND 4WO 
 2.. 112 PROPERTIES OF RADAR TARGETS [SEC. 317 miles onlarge targets areobserved with 3-cm systems such asthe AA”/- APQ-13 and AN/APS-15, while with 1.25-cm systems like theAX/APS- 22the ranges available atpresent areabout 15miles onground return and 30miles onlarge targets, foraverage atmospheric conditions inthe Eastern United States. 
 The phenomenon being measured is a low-level divergent outflow (or microburst). Figure 23.8 shows another example of air motion fields in a vertical plane orthogonal to an intense squall line in California.75 Rapid Scanning. The use of multiple-doppler radars has provided dramatic new information on the internal winds in large precipitating systems- information that can be obtained in no other way. 
 IRE Trnns., vol. MIL-6. pp. 
 Triangular arrangement of elements.• 5 2-154 If the elements of a planar array are arranged in a  pattern of equilateral triangles rather than squares, a savings can be had in the total number of  elements needed. This assumes that the number of elements in an array is determined by the  requirement that no spurious beams (grating lobes) appear in the radiation pattern. The  reduction in the number of elements depends on the solid angle over which the main beam is  positioned. 
 An esti - mate of radar biases between two radars can be obtained from a long-term average of  the difference between predicted and measured coordinates on all tracks that have a  substantial number of detections from both radars.78 7.5 UNLIKE-SENSOR INTEGRATION A number of sensors can be integrated: radar, identification friend or foe (IFF), the  air traffic control radar beacon system (ATCRBS), infrared, optical, and acoustic. The  sensors that are most easily integrated are the electromagnetic sensors, i.e., radar, IFF,  and strobe extractors of noise sources or emitters. FIGURE 7.41  Comparison of detection fusion and track fusion approaches. 
 (4a)forthe maximum range ofdetection, R~..: 4PuA‘jzR J.s,=—4~S~,.A2”(4b) Atthis point itmay bewell togetanidea oftheorder ofmagnitude ofthe quantities involved byinserting numbers not unusual inwartime pulse-radar practice. Ifwechoose X=0.10 ft(=3.0 cm), P=10’ watts, A=10ft2,j=0.6, u=100 ftz (typical for small aircraft), & =5X10–12 watts, weobtain R~..=155,000 ftor29statute miles. Weobserve that a16-fold increase intransmitted power isrequired to double themaximum range; ontheother hand, itwould appear that R~.. 
 79· 1°2 Deviations from Rayleigh were found at 70 and  95 GHz. and the backscatter at 95 GHz was observed to be less than at 70 GHz. The back­ scatter ~t .. 
 LOOP TRACKING MAY CONTINUE !LTHOUGH THE ELEVATION 
 BUTION &OR A BROADSIDE BEAM P    AND   '   O .G    AND THE ELEMENT GAIN IS 'E   O &IGURE  SHOWS A THEORETICAL EXAMPLE OF THE ARRAY AND ELEMENT FACTORS AND THE  RESULTING PATTERN FOR A  
 LATE THE POWER SCATTERED IN SOME OTHER DIRECTION THAN BACK TO THE TRANSMITTER  A  BISTATIC  SITUATION ! BISTATIC 2#3 MAY BE DEFINED FOR THIS CASE AS WELL AS FOR BACKSCATTERING  PROVIDED IT IS UNDERSTOOD THAT THE DISTANCE  2 IS MEASURED FROM THE TARGET TO THE RECEIVER . 
 11.4  11.3 RCS Prediction Techniques  ...................................  11.18  Exact Methods  ...................................................  11.20 Approximate Met hods  ........................................ 
 Marchant: Structural Aspects: pt 1, Elementary Design Considerations.  ctiap. 7 of " Meclianical Engineering in Radar and Communications." C. 
 The boundaries of the various regions are wide to indicate the wide  variation of the data within the classes of terrain. Figure 13.9 illustrates airborni./data at X and  L bands obtained by the Naval Research Laboratory.37 The azimuth beamwidth was 5° and  the pulse width was 0.5 µs at each frequency. The lack of smoothness of the data is due, in  part, to the fact that the data was not all taken at the same time. 
 .”  Britain had for many years been a prominent leader in  pure research on the travel of radio waves, on the things  which make long-distance radio communication pos-  sible, and on the things which still cause it to be imper-  fect. The Department of Scientific and Industrial  Research had followed the very enlightened policy of  accepting the advice of its Radio Research Board that the  best contribution which it could make to better radio  communication was the long-term and fundamental  investigation of the basic processes, rather than the  short-term search for individual remedies to individual  problems. Whether this pure research should be  fostered and supported by industry, by scientists them-  selves, or by the State has now become not only a political  but an international matter. 
 L. Gray, “Estimating the effect of feed support member blocking on antenna gain and sidelobe  level,” Microwave J ., pp. 88–91, March 1964. 
 ................................  6  Digital Modulation  ................................ ................................ 
 Guard Blanking Loss. This is the detectability loss in the main channel caused by spurious blanking from the guard channel. (See Fig. 
 Ê 
 Phillips: "Theory of Servomechanisms," MIT Radiation  Laboratory Series, vol. 25, McGraw-Hill Book Company, New York, 1947.  4. 
 26. Ward, H. R.: The RAMP PSR, A Solid State Surveillance Radar, IEE Int. 
 IRE, vol. 44, pp. 1713-1718, December 1956. 
 The log-FTC has the property that when the input clutter or noise is described by a  Rayleigh pdf, the outptrt clutter or noise is a constant independent of the input amplitude.  Thus the log-FTC receiver has a constant false-alarm rate. As with any CFAR, the false-alarm  rate is maintained constant by a sacrifice in the probability of detection. 
 Since each phase shifter in the series-fed linear array of Fig. 8.4~ has the same value of  phase shift, only a single control signal is needed to steer the beam. The N-element parallel-fed  linear array similar to that of Fig. 
 News, vol. 8, pp. 49-54, September 1978. 
 6.12). Without these precautions off-axis sidelobes can be generated by banana-shaped sections. Most shaped reflectors take advantage of the shaping to place the feed outside the secondary beam. 
 RATION  SUCH AS FREQUENCY  CELL SIZE  POLARIZATION  GRAZING ANGLE AT THE SURFACE  ETC  CAN BE SPECIFIED  SELECTING AND QUANTIFYING THE ENVIRONMENTAL PARAMETERS IS QUITE ANOTHER MATTER &IRST  IT HAS NOT  ALWAYS BEEN CLEAR WHICH ENVIRONMENTAL PARAMETERS ARE IMPOR 
 RESISTANCE CHARGIN G TIME (IGH 
 which is  OD 2.776t2  exp ( -j2nfr) dt . -a3  n2f2ti = k, exp ---- 1 2.776 1  where k, = constant. Since this is a gaussian function, the exponent is of the form f 2/2a; where  aI = standard deviation. 
 TARGET ENERGY RATIOS IN EXCESS OF  D" 4HIS PLACES SEVERE DEMANDS ON THE SPECTRAL PURITY AND DYNAMIC RANGE OF THE RADAR WAVEFORM GENERATOR  TRANSMITTING  AND RECEIVING SYSTEMS (IGH SENSITIVITY HAS THE SIDE EFFECT OF REVEALING THE ECHOES FROM  MANY NATURAL SCATTERERS IN THE IONOSPHERE  AS WELL AS THE SPECTRUM OF GROUND CLUTTER THAT  HAS BEEN SPREAD IN DOPPLER BY THE FLUCTUATIONS OF THE SIGNAL PROPAGATION PATH )N ORDER TO RECOGNIZE AND SUPPRESS THESE UNWANTED RETURNS  WHICH CAN OBSCURE TARGET ECHOES  AN UNDERSTANDING OF THE UNDERLYING PHYSICS IS ESSENTIAL ! DISTINCTIVE REQUIREMENT OF A SKYWAVE RADAR IS A SUITE OF AUXILIARY SYSTEMS TO MON 
 End-Fed Series Feed . An end-fed series array is shown in Figure 13.31 a later   in this chapter. The radiating elements are in series and progressively farther and far - ther removed from the feed point. 
 Because of the  usual lack of complete information, most engineering design requires, at some point,  the judgment and experience of the design engineer in order to succeed. The Radar Equation in Conceptual Design.  The radar equation is the basis  for conceptual radar system design. 
 4.2 are called bipolar, since they contain both positive and negative  amplitudes.  Moving targets may be distinguished from stationary targets by observing the video  output on an A-scope (amplitude vs. range). 
 Levush, and D. Abe: “A review of the development of multiple-beam  klystrons and TWTs,” Naval Research Laboratory, Washington, DC, MR/6840-03-8673,  March 17, 2003. 10. 
 W.: Broad-Band Balanced Duplexers, IRE Trans., vol. MTT-5, pp. 4-12, January, 1957. 
 ARRAY ELEMENTS THAT REDUCES NUMBER NEEDED v  )2% 4RANS  VOL !0 
 IthastheproperphasecPm+¢n ateachelement tosteerinthetwodirections. Themixerwouldbefollowed byapower amplifier ifatransmitter, oritmightbeused.toobtainthelocaloicillator frequency ifa receiver. OnlyM+N-2phaseshiftersarerequired, butthemixerandpoweramplitler required ateachelement addstothecomplication. 
 and Remote  Sensing , vol. 30, pp. 973–980, 1992 174. 
 ” Rapid photographic projection. The last two methods mentioned are the only ones developed fully enough during thewar towarrant further description. I .-+Image plane1A Spherical mirror arclamp,“1~ Fieldlens FIG-.7.6.—Schmidt projection system forskiatron. 
 AVERAGING CONSTANT FALSE ALARM RATE #! 
 49. Kock, W. E.: Metallic Delay Lens, Bell Sysrrm Tech. 
 464–466, 1999. 37. F. 
 Many theoretical models for radar return from the  ground assume a rough boundary surface between air and an infinite homogeneous  half space. Some include either vertical or horizontal homogeneities in the ground  properties and in vegetative or snow covers. Surface descriptions suitable for use in mathematical models are necessarily greatly  idealized. 
 SEC.1.6] THEEARLY HISTORY OFRADAR 13 information afforded byradar isusually atleast asimportant asisthe radar itself. Agood organization can make excellent useeven ofinferior radar information, aswas proved bythe success ofthe British Home Chain ofradar stations, thefirst large-scale radar installation tobemade. An inadequate organizational set-up can doapoor job, even though provided with splendid radar from thetechnical standpoint. 
 Integration may be accomplished in the radar receiver either before the second detector  (in the IF) or after the second detector (in the video). A definite distinction must be made  hctween these two cases. Integration before the detector is called predetection, or coherent,  integration, while integration after the detector is called postdetection, or noncoherent, integra­ tion. 
   !)2"/2.% -4)  Î°ÓÇ FREEDOM IN 34!0 WHILE STILL PROCESSING THE FULL APERTURE SPATIALLY 4HIS IS SIMILAR TO  A CONVENTIONAL -4) OR $0#!  ARCHITECTURE CASCADED WITH DOPPLER FILTERING 7E CALL THIS ARCHITECTURE A PRE 
 Franklin, J. H. Ganton, and J. 
 TheCassegrain principle iswidelyusedintelescope designtoobtainhighmagnification witha physically shorttelescope andallowaconvenient rearlocation fortheobserver. Itsapplication tomicrowave reflector antennas permitsareduction intheaxialdimension oftheantenna,just asinoptics.Butmoreimportantly iteliminates theneedforlongtransmission linesandallows greaterflexibility inwhatcanbeplacedatthefocusoftheantenna. Theprinciple oftheCassegrain antenna isshowninFig.7.11.Itisatwo-reflector system withthelarger(primary) reflector havingaparabolic contouranda(secondary) subreflector withahyperbolic contour. 
 R. Boorstyn, “Single-tone parameter estimation from discrete-time observations,”  IEEE Trans. Information Theory , vol. 
 1975.  XO Kanynck. t\ J.: Tiansirnt Re,ponse of Tracking Filters with Randomly Interrupted Data. 
 EST TO CALCULATE THE DEGRADATION OF THE DETECTION RANGE WITH RESPECT TO SELF 
 ¯ ¯  \  \ \   QQ QQQQ QQ Q     \ 
 First, microwave receivers, even asthis iswritten, have been brought soclose tothe pinnacle ofideal performance that itiswell forthe radar engineer to appreciate the nearness, and the finality, ofthe goal. Second, thermal noise, although itisnot wholly toblame forthe noise background in microwave receivers, provides avery convenient standard interms of which theperformance ofanactual receiver can bespecified. Weshall define, astheover-all noisejigureNofareceiver, theratio of signal power available from the antenna tokZ’@,2when the mean noise power and the signal power areequal asobserved atsome stage inthe receiver where both have been amplified sohighly astooverride com- pletely any noise introduced bysucceeding stages. 
 The sea echo also depends on such radar parameters as frequency, polarization,  grazing angle, and, to some extent, the size of the area under observation. Although there is  much that is known about the nature of sea clutter, the quantitative, and sometimes even the  qualitative, effects of many of the 'above factors are not known to the degree often desired. The  relative uniformity of the sea over the oceans of the world makes it easier to deal with sea  clutter than with land clutter, but it is difficult to collect data at sea under the controlled and  reproducible conditions necessary to establish quantitative causal relationships. 
 FED &ERRITE PHASE 
 20.44  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 then rapidly falls. Figure 20.19 b is for nighttime. All the curves are the same as in  Figure 20.19 a except for atmospheric noise. 
 A coinparison of the nose-on cross section of several cone-shaped objects is given  in Fig. 2.13.  Shaping of the target, as with the cone-sphere, is a good method for reducing the radar  cross section. 
 BASED HIERARCHI 
 28. Rowlands, R. 0.: Detection of a Doppler-Invariant FM Signal by Means of a Tapped Delay Line, J. 
 Ice clouds  give attenuations about two orders of magnitude smaller than water clouds of the  same water content. The attenuation of microwaves by ice clouds can be neglected for  practical purposes. Attenuation by Rain. 
 Moaveni, M. K.: Radio Interference in Helicopter-Borne Pulse Doppler Radars, IEEE Trans., vol. AES-14, pp. 
 Two-dimensional inverse fast Fourier transform is performed to generate the ISAR image. Step 3 : Calculate entropy of the ISAR image and set tolerance Twhich is used to stop the iterations. IfEl(I)−El−1(I)is greater than the T, the iteration continues; otherwise, the process terminates. 
 18, no. I. June­ .July. 
 Thecrossed-field amplifier iscapableofpeakpowerscomparable tothoseoflinear-beam tubes,andaverage powersonlyslightlylessthanthoseachieved withlinear-beam tubes. II> Efficiencies greaterthan50percentarecommon. Thebandwidths aresimilartothoseobtained withthetraveling-wave tube.Forward-wave CFAsgenerally havebandwidths from10to25 percent; backward-wave CFAs,lessthan10percent. 
   05,3% #/-02%33)/. 2!$!2   n°{£ 4HE MATCHED FILTER OUTPUT SIGNAL  YT  IS FOUND BY CONVOLUTION OF  ST  WITH THE  MATCHED FILTER IMPULSE RESPONSE HMFT    YT UT U T TE D TJF TD        `` 
 MODE FEED AFTER 0 7 (ANNAN Ú )%%%   . 
 FIGURE  2.95 Anomalous propagation (ducting): ( a) 100-nmi maximum  range and ( b) 50-nmi maximum range ch02.indd   95 12/20/07   1:52:15 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 RACY  /RBIT SELECTION FOR AN OCEAN ALTIMETER REQUIRES CONSIDERATION OF THE IMPACT OF AN  ORBITS INCLINATION  REPEAT PERIOD  AND ALTITUDE &OR EXAMPLE  IF THE OBJECTIVE IS ABSOLUTE SEA 
 The contraction imp lies that the quantity measured is range.  While this is correct, modern radars are also used to measure range and angle.   The following figure shows the operating principle of primary radar. 
 A waveform satisfies the requirements of detection if its energy is  sufficiently large and if the receiver is designed in an optimum manner, such as a matched-filter  receiver. Waveform shape is important only as it affects the practical design of the matched  filter. The ability of a particular waveform to satisfy the requirements of accuracy, ambiguity,  resolution, and clutter rejection may be qualitatively determined from an examination of the  ambiguity diagram. 
 By slightly sacrificing the accuracy of  angle tracking (due to less slope sensitivity), lower sidelobes can be achieved. Such a pattern  whicli sacrifices slope sensitivity for lower sidelobes has been called a tempered double-trull  rii/l>rrttce pattert~.~~  The tempered double-null is more suited to mechanically steered trackers than to phased-  awince it is basically a null balance technique that does not achieve full accuracy  until it goes through a settling process. A technique that can operate on the basis of a single  pi~lse. 
 Ê " *, 
 These readings  are then translated into figures by switching on the timing  “Cal’ (calibrator) pips, which the navigator can match with the  received signals. These figures relate not to mileage or bear-  ings direct, but to numbered lines on the Gee charts. In the  fmal picture this position is seen being ascertained and marked  with an X. 
 Graf: The Reduction of Radar Glint by Diversity Techniques, IEEE Trans., vol.  AP-19, pp. 462-468, July, 1971. 
 However, SAR imaging is affected by various radar parameters and environmental factors, which makes it quite difﬁcult to learn directly from SAR eddy images. In order to interpret and evaluate eddy images, developing a proper simulation method is necessary. However, seldom has a SAR simulation method for oceanic eddies, especially for shear-wave-generated eddies, been established. 
 [ · t/11 sin (Ni/J/2)  " 2 sin (t/1/2) (8.2)  Incoming signal  -d----d ---d r  Figure 8.1 N-element linear array. 1111' t:11:CIRONl('Al.l.Y STEERED PIIASl'D ARRAY ANTENNA IN RADAR 281  The first factor is a sine wave. of frequency w with a phase shift (N -I )lj;/2 (if the phase  reference were taken at the center of the array, the phase shift would be zero), while the second  term represents an amplitude factor of the form sin (Nlj;/2)/sin (tj,/2). 
 3. J. Neyman and E. 
 This is an important aspect of  the detection process since the initiation of a track after a new target is detected requires a  sequence of radar dwells that can consume the resources of the radar and the computer.  The 1rack-i11iriatio11 process after a new detection has been established is a demanding one.  The radar must observe the target a significant number of times within a modest time interval  to quickly cstahlish the target's direction of travel and speed. 
 An Efﬁcient Solution to the Factorized Geometrical Autofocus Problem. IEEE T rans. Geosci. 
 A similar technique using anode-voltage control with two phosphors having the same  color but different decay times can provide a CRT display with variable persistence. It is also  possible to achieve a multicolor tube with variable persistence.  Although color displays may be pleasing and attractive to the operator, the applications  in which they have proven superior to properly coded monochromatic displays apparently  are fewer in number than might have been anticipated."  Bright displays. 
 Feedback energy might  arise in the TWT from the renection of a portion or the forward wave at the output coupler.  The feedback must be eliminated if the traveling-wave amplifier is to function satisfactorily.  Energy traveling in the backward direction may be reduced to an insignificant level in most  tubes by the insertion of attenuation in the slow-wave structure. 
 Figure2.10isaplotofthebackscatter crosssectionofalongthinrodasafunction of aspect. 26Therodis39A.longandA./4indiameter, ~ndismadeofsilver.Iftherodwereofsteel insteadofsilver,thefirstmaximum wouldbeabout5dBbelowthatshown.Theradarcross sectionofthethinrod(andsimilar:objects)issmallwhenviewedend-on(0=0°)sincethe physicalareaissmall.However, atnearend-on,wavescoupleontothescatterer whichtravel. Measured ---- Colculoted  F-igure 2.10 Backscatter cross section of a lotig thin rod. 
 It guaranties the Doppler displacement in the spectrum of the ISAR signal to realize the necessary azimuth resolution of the asteroid’s image. Considering that the ISAR signal from the asteroid is very weak in comparison with the thermal noise, the experiment is carried out assuming the signal is obscured by additive white Gaussian noise, an appropriate model of signal disturbances in deep space navigations and communications. Assume as follows: number of imaging segments n=100, S=10−26⎭bracketleftBigW m2·Hz⎭bracketrightBig ,ΔF=0.15×109Hz, Dpr=300 m, λ=0.03 m, asteroid’s diameter D=29 m, Tint=10−6s, then the signal to noise ratio calculated by (7) is equal to−15 dB. 
 These effects are prevented by a technique known as sensitivity time control, which causes the radar receiver sensitivity to vary with time in such a way that the amplified radar echo strength is independent of range. Search radars often employ a cosecant-squared antenna pattern whose gain diminishes with increasing elevation angle. The pattern restricts the power at high elevation angles, since an aircraft at a high elevation angle is necessarily at close range and little power is required for detection. 
 [ CrossRef ] 8. Liu, J.; Kuga, Y.; Ishimaru, A.; Pi, X.; Freeman, A. Ionospheric effects on SAR imaging: A numerical study. 
 Ducting occurswhentheupperairisexceptionally warmanddryincomparison withthe airatthesurface.Thereareseveralmeteorological conditions whichmayleadtotheformation ofsupcrrefracting ducts.31.32Overland,ducting isusuallycausedbyradiatiorVof heatfrom theearthonclearnights,especially inthesummer whentheground ismoist.Theearthloses heat.anditssurfacetemperature falls,butthereislittleornochangeinthetemperature ofthe upperatmosphere. Thisleadstoconditions favorable toducting, thatis,atemperature inver­ sionatthegroundandasharpdecrease inthemoisture withheight.Therefore, overland massesducting ismostnoticeable atnightandusuallydisappears duringthewarmest partof theday. Another common causeofducting isthemovement ofwarmdryair,fromland,over coolerbodiesofwater.Warmdryairblownoutoverthecoolerseaiscooledatthelowest layersandproduces atemperature inversion. 
 CATES THAT OUR !$# PRODUCES  BITS OF DIGITAL OUTPUT !$#S PROVIDE APPROXIMATELY  D" OF DYNAMIC RANGE PER BIT  SO OUR  
 Atthe same time, the amplifier must becapable ofamplifying pulses several hundred microseconds inlength and yet befully sensitive toa weak signal immediately following. Itmust recover immediately from a signal thousands oftimes stronger than theminimum discernible signal. Frequently special requirements are placed onthe receiver. 
 III and most subsequent marks operated with a wavelength of 3 cm. A prototype 3 cm ASV radar was ASV Mk. VII, described in chapter 5and this would form the basis for long-range ASV development after WWII. 
 DIVIDING STEPS HAS TO BE WELL MATCHED OVER THE BAND )F MISMATCHES ARE PRESENT  THEY WILL BE SEPARATED BY MANY WAVELENGTHS AND WILL ADD UP TO GIVE FREQUENCY 
 ch14.indd   29 12/17/07   2:47:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 
 The nutating feed requires a flexible joint. If the antenna is small, it  may be easier to rotate the dish, which is offset, rather than the feed, thus avoiding the problem  or a rotary or fiexible RF joint in the feed. A typical conical-scan rotation speed might be  30 r/s. 
 SOURCE CAPACITANCE WILL AFFECT THE /&& 
   PP n  -AY   * " +ELLER  h$IFFRACTION BY AN APERTURE v  * !PPL 0HYS  VOL   PP n  !PRIL   * " +ELLER  h'EOMETRICAL THEORY OF DIFFRACTION v  * /PT 3OC !M  VOL   PP n    2 ' +OUYOUMJIAN AND 0 ( 0ATHAK  h! UNIFORM THEORY OF DIFFRACTION FOR AN EDGE IN A PERFECTLY  CONDUCTING SURFACE v 0ROC )%%%  VOL   PP n  .OVEMBER    * * "OWMAN  0 , % 5SLENGHI  AND 4 " ! 3ENIOR EDS    %LECTROMAGNETIC AND !COUSTIC 3CATTERING  BY 3IMPLE 3HAPES  !MSTERDAM .ORTH 
 ccEEEEE WTAIIS       WHERE @  DESCRIBES THE BREADTH OF THE TIME CONSTANT DISTRIBUTION FROM A SINGLE RELAXATION   @      TO AN INFINITELY BROAD DISTRIBUTION   @      WITH A COMMON PROCESS $IFFERENT  POLARIZATION PROCESSES MAY BE DESCRIBED BY A SERIES OF #OLE 
 LISH UPPER BOUNDS ON THE ACHIEVABLE PERFORMANCE IN A PRECISELY SPECIFIED CLUTTER ENVIRONMENT )T SHOULD BE NOTED  HOWEVER  THAT OWING TO THE EXTREME VARIABILITY OF THE CHARACTERISTICS OF REAL CLUTTER RETURNS POWER LEVEL  DOPPLER SHIFT  SPECTRUM SHAPE  SPECTRAL WIDTH  ETC  ANY ATTEMPT TO ACTUALLY APPROXIMATE THE PERFORMANCE OF SUCH OPTIMUM FILTERS FOR THE DETECTION OF TARGETS IN CLUTTER REQUIRES THE USE OF ADAPTIVE METHODS 4HE ADAPTIVE METHODS MUST ESTIMATE THE UNKNOWN CLUTTER STATISTICS AND &)'52%   -4) IMPROVEMENT FACTOR AS A FUNCTION OF THE RMS VELOCITY SPREAD OF CLUTTER FOR   A TWO 
 °£Ó  2!$!2 (!.$"//+  INDIVIDUAL APERTURE WOULD BE IN PHASE !S  THE TARGET MOVES OFF AXIS IN EITHER DIREC 
 L..andP.M.Liebman: AReportontheSperryDomeRadar.Microwal'e J.•vol.22. PI'·6569.March,1979. UO.Hansen, R.c.:Conformal Arrays,MierOl\'(/l'e J.,vol.13,p.39,April,1970. 
 For example, with a constant amplitude distribution, the difference-pattern array factor calculated by the exact vector addition of all radiating elements is 1 - cos Mr(s/X)(sin B - sin B0) E1 /A\ _ _ N sin Tr(,s/X)(sin B - sin B0) The Fourier transform gives the same expression with the sine in the denomina- tor replaced by its argument, giving (in the denominator) ir(fl/\)(sin B - sin B0), where a = Ns. For small scan angles B0 and small values of B the expression sin B - sin B0 may be approximated by B - B0. For larger values of B0, the expression sin B - sin B0 may be expanded to give the response in the general direction of the (narrow) scanned beam in terms of the small angle (B - B0): sin B - sin B0 * aB - B0) cos B0 (7.13) This gives, with Eq. 
 Thedipoleisalwaysused overarenecting groundplane,oritsequivalent, inordertoconfinethemainbeam'radiation to theforward direction. Slotscutintothewallsofawaveguide aresimilarinmanyrespectstothedipolesincethe slotistheBabinet equivalent ofthedipole.Aslotarrayisgenerally easiertoconstruct atthe highermicrowave frequencies thananarrayofdipoles. Although theslotsmaybeineither thebroadorthenarrowwallofthewavegu'ide, thenarrowwallisgenerally preferred (edge slots)sothat~.thewaveguides maybestacked sufficiently closetoobtainwide-angle scan without gratinglobes.Thewaveguide slotarrayantenna ismoresuitedforone-dimensional scanning thanscanning intwocoordinates. 
 Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters.  SOLID-STATE TRANSMITTERS  11.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 deliver the power. Higher numbers of paralleled fingers necessarily lead to decreasing  input and output impedances, further complicating the ability to provide the desired  impedance match over the desired bandwidth. 
 C. MacDonald: Terrain Clutter Measurements in the Far North. Report o{  NRL l'royress. 
 1949.. 12. Hansen, R. 
 1992 ,30, 403–411. [ CrossRef ] 197. Sensors 2019 ,19, 2161 3. 
 DIRECTIVE JAMMERS OPERATING AGAINST THEIR HOST RADAR  "ECAUSE THE JAMMER USES A HIGH 
 DERIVED POLYPHASE 0# CODES v  )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONICS 3YSTEMS   VOL   NO  PP n  *ULY .   05,3% #/-02%33)/. 2!$!2   n°{Î  " , ,EWIS AND & & +RETSCHMER  *R  h,INEAR &REQUENCY -ODULATION $ERIVED 0OLYPHASE 0ULSE  #OMPRESSION #ODES v  )%%% 4RANS ON !EROSPACE AND %LECTRONICS 3YSTEMS   !%3 
 STATE TRANSMITTER USING TRANSISTOR AMPLIFIERS BECAUSE IT ALREADY USED A LONG PULSE WAVEFORM WITH A HIGH DUTY CYCLE AND PULSE COMPRESSION  WHICH IS WHAT SOLID 
 Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 4.44  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 CFAR Loss.  This loss is caused by an imperfect estimate of the detection thresh - old compared with the ideal threshold. 
 Nevertheless, our proposed method is mainly focused on the features along the eddy spirals, since fully simulating the eddy features is too complicated; besides, eddy spirals are usually the only features which are detectable from actual SAR images.Our conclusions of the eddy spiral features may facilitate eddy detection, such as supervised or semi-supervised machine learning of shear-wave-generated eddy detection. We believe that the main results of this study are quite robust and not very sensitive to future model modiﬁcations. 320. 
 300.  March, 1967.  47. 
 27, pp. 375–383, 1989. 116. 
 SCALE 
 NOISE RATIO 4HUS FOR THESE RANGES  THE RADAR RETURN IS OVERWHELMED WITH CLUTTER &)'52%   !2%03 HEIGHT VERSUS RANGE COVERAGE FOR SURFACE 
 1961 96.Tischer, F.J.:HGuideandLaminated Dielectric Slab.IEEETrails.•vol.MIT-18. pp.9-15.Janu­ ary.1970. 97.Millimeter Waveguide Systems. 
 Goto. N., and D. K. 
 Also, more information on tracked targets may need to be easily available.  Much of this additional data can be automatically supplied by AIS. The radar data  often has to be relayed many miles, to perhaps a number of operational centers. 
 Gross: Beam Shape Loss and Surveillance Optimization for Pencil Beam  Arrays, lEEE Trans., vol. AES-5, pp. 674-675, July, 1969. 
 3.21  Filtering Problems Associated with Mixer  Spurious Responses  .......................................  3.22  3.8 Logarithmic Devices  ...............................................  3.25  Characteristics  ................................................... 
 TERS AND AGRICULTURAL IRRIGATORS  -OST AREAS HAVE LARGE NUMBERS OF VEHICLES AND SCATTERERS THAT COULD BE VEHICLES )T IS  TYPICAL TO HAVE UP TO   BONA FIDE '-4S IN THE FIELD OF VIEW 0ROCESSING CAPACITY  MUST BE ADEQUATE TO HANDLE AND DISCRIMINATE THOUSANDS OF HIGH  3.2 THRESHOLD CROSSINGS  AND HUNDREDS OF MOVING TARGETS OF INTEREST 5SUALLY MULTI 
 Rast, Jr.: The Measurement of Noise in Microwave Transmitters,  IEEE Trans., vol. MTT-25, pp. 294-318, April, 1977. 
 AVG ,OSS  LS PH      S PL2T! ,OSS   . 
 In the absence of nonlinearities, the two techniques in Fig. 20.5a and b are mathematically identi- cal because Im (—^-) = ImU + j|j = Im | cos 4> (20.17) Hence, they both provide the fundamental accuracy performance of full-vector monopulse processing, given by 11 wA -/W2IIrmse - —: — (20.18) l/l(2;t)1/2 . FIG. 
 S HS4 4.             rr 
 V. Jakowatz, D. E. 
 LATION OF REFLECTIONS " 
 Furthermore in GT, the frequency  over the effective area of the antenna is cont ained quadratically.  Consequently, for the estimation  of the frequency dependence of the range of coverage, the influence of frequency on the follo w- ing characteristics must be considered:    Antenna gain    Propagation attenuation    Cross- section of the reflectio n . Radar System Engineering  Chapter 3 – The Radar Equation  15      3.2 Radar Equation for Extended Targets   For extended targets, meaning targets that are located in the far field,  € Rmax is proportional  € 2  to € 4, depending on the distance and characteristics of the t arget. 
 Then A’=azbz=a2A2/~2, and inserting this inEq. (4b) wehave J4Puf‘azR—m..=4iTSmirJ32”(5) The range nolonger depends explicitly onthewavelength. From what hasbeen said itshould beclear that anexcess ofantenna gain, inany direction, over what isneeded tomeet any requirement for _——-— FIG.2.1.—A radiation pattern ofthisshape iscalled a“fanbeam. 
 7.9b produces an asymmetrical pattern since the  transmission line is not in the center of the dish. A rear feed not shown is the Cutler feed,g a  dual-aperture rear feed in which the waveguide is in the center of the dish and the energy is  made to bend 180" at the end of the waveguide by a properly designed reflecting plate. The rear  feed has the advantage of compactness and utilizes a minimum length of transmission line. 
 63. Donaldson, R. J., Jr.: Vortex Signature Recognition by a Doppler Radar, J. 
 The efficiency quoted for most tubes is the RF conversion efficiency, defined as the RF  power output available from the tube to the d-c power input of the electron stream. This is the  efficiency of interest to the tube designer. The system engineer, however, is more concerned  with the overall transmitter efficiency, which is the ratio of the RF power available from the  transmitter to the total power needed to operate the transmitter. 
 they can operate with low  control power, and are compact in size. They lend themselves well to microwave integrated  circuit construction, and are capable of being used over the entire range of frequencies of  interest to radar although their losses are generally less and their power handling is generally  higher at the lower frequencies.  There are three basic methods for employing semiconductor diodes in digital phase  shifters, depending on the circuit used to obtain an individual phase bit. 
 The major benefit of a phased array with respect to tracking is in the area of  track initiation.75,76 Phased arrays use a confirmation strategy to initiate tracks rapidly.  That is, after the association process, all unassociated detections generate confirmation  dwells to confirm the existence of a new track. The initial confirmation dwell uses the  same waveform (frequency and PRF, if a pulse-doppler waveform) but may increase the  energy. 
 This returned energy is called an ECHO, just as it is in sound terminology. Radar sets use the echo  to determine the direction and  distance of the reflecting object.   The word radar is a contraction of   RAdio Detecting And Ranging   As implied by this contraction, radars are used to detect the presence of an aim (as object of  detection) and to determine its location. 
 357–362. 113. L. 
 Analysis of recent ground subsidence in the sibari plain (Italy) by means of satellite sar interferometry-based methods. Int. J. 
 Thus (referring toFig. 10.16), ifthe magnetron isoperated ataconstant magnetic field, say 2100 gauss, the relations ofvoltage and current aregiven bypoints on theH=2100 gauss line. (At20kv,thecurrent drawn will be48amp.) Onthe same chart are plotted the lines ofconstant power output. 
 Not only must therectifier-filter power supplies fortheradar circuits operate atany frequency from 400 to2400 cps; they must also tolerate poor voltage regulation and poor waveform intheprimary power supply. The presence inthe same aircraft ofhigh-power radio transmitters, sensitive radio receivers, and ahigh-voltage ignition system makes it necessary toshield and filter theradar setadequately toprevent itfrom interfering with other equipment, and toprotect itfrom interference arising inother equipment. Limitations Imposed byPersonnel.—A radar fornavigational use in allsorts ofaircraft must bemanufactured ingreat quantity with ease and economy, must besosimple touseand understand that only ashort period oftraining isnecessary tooperate itadequately, and must beso easy tomaintain that itcan bekept insatisfactory condition with little maintenance effort. 
 42. Cook, C. E., and M. 
 NESS OF %#- TO BE ASSESSED 4HE THREATS TO A 3!2 ARE BARRAGE JAMMING  SPOT JAMMING  RANDOM  PULSE JAMMING   AND REPEATER JAMMING 2EPEATERDECEPTION JAMMING IS A MAJOR THREAT BECAUSE IT MIGHT NOT BE RECOGNIZABLE  WHEREAS THE OTHERS ARE  AT LEAST IN PRINCIPLE  RECOGNIZABLE 4HE IMPACT OF EACH THREAT AND THE POSSIBLE COUNTERMEASURES ARE DESCRIBED IN THE REMAINING PART OF THIS SECTION u "ARRAGE JAMMER 4HE DISTURBANCE NOISE EXTENDS OVER THE ENTIRE SWATH OF THE 3!2  IMAGE  AND IT SHOWS GENERALLY A UNIFORM INTENSITY 4HE RADAR IMAGE OF BARRAGE JAM 
 STATE TRANSMITTER CANNOT )N THE PAST  AVERAGE POWERS OF RADAR TRANSMIT 
 I-iuyge~is' principle may be applied it1 the far field by dividing the plane  wave across the circular aperture into a great many spherical wavelets, all of the same phase  but of different amplitude. To find the field intensity at a point a distance R from the antenna,  the amplitudes of all the waves are added at the point, taking account of the proper phase  relationships due to tlie difference in path lengths. Th'e field intensity at a distance R is thus  proportional to  where ro is tlie radius of the aperture. 
 Usually the doppler shift of clutter returns is caused by the wind field, and early  attempts of compensating in the MTI have varied the coho frequency sinusoidally as a  function of azimuth based on the average wind speed and direction. This approach is FIGURE  2.84 Available Nyquist bandwidth vs. A/D converter sampling rate0 1.5 1 0.5 2 2.5 3 3.5 4 4.5 500.050.10.150.20.250.30.350.40.450.5 M = 1 M = 2 Relativ e A/D sampling rate –fAD/fIFRelative Nyquist Bandwidth – BNQ/fAD ch02.indd   80 12/20/07   1:46:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 7.28.  They are not to be confused with the usual elevation and azimuth angles. The antenna lies in  the x-!! plane of Fig. 
 Both the operating and thedynamic orincremental impedance areimportant; the former determines the rate at\vhich po\ver will beabsorbed from the. 364 THEMAGNETRON ANDTHEPULSER [SEC. 10.8 pulser, and the latter determines insome cases the variation inpower output with small incremental changes inapplied voltage. 
 Passive ISAR Scenario and Asteroid Kinematics and Geometry Consider a 3D regular grid, where the asteroid’s geometry is described. The grid is deﬁned in Cartesian system O/primeXYZ and moves on a rectilinear trajectory at a constant speed in the coordinate system Oxyz . The mass-center of the object, the geometric center of the 3D grid and the origin of the coordinate system O/primeXYZ coincide in point O’ Figure 2. 
 M .. K. S. 
 .The two antennas are  separated by d = vT. [v = platform speed , T = pulse repetition interval.] A SAR image  is then formed by conventional techniques. The result is shown in Figure [17.10 a]. 
 POWER  NOISE 
 The 100 kW ASV Mk. IIA systems onSunderlands were used for this purpose. However, the number of aircraft required for this was excessive and the use of ﬂooding was abandoned. 
 The operator can communicate in an interactive manner with the computer by such  means as a keyboard, light pen, track ball, or even voice entry. Sometimes an auxiliary  CRT display is mounted adjacent to the main radar display to provide tabular data and  other information that would otherwise clutter the main display.  The characters and symbols that constitute the synthetic information may be inserted  on a CRT during the radar dead time at the end of the sweep prior to the triggering of the  next pulse. 
 Such adevice iscalled a“single stroke” generator or. SEC. 13.7] GENERA TION OF RECTANGULAR WAVEFORMS 497 “flip-f lop.” Ithaswide application both incases where thewave- form isdirectly used and intiming or“delay” circuits. 
 Robinson, T. A.: Application of Electronic Distance Measuring Equipment in Surveying, IRE Trans.,  vol. MIL-4, pp. 
 FREE   SIDELOBES  #ONTROL THE PHASE AND AMPLITUDE ERRORS THAT CONTRIBUTE TO THE RANDOM SIDELOBES /F THE TWO  CONTROLLING ERRORS FUNDAMENTALLY LIMITS SIDELOBE PERFORMANCE 4HE  EFFECTS OF ILLUMINATION FUNCTION AND ERRORS ARE DISCUSSED BELOW )LLUMINATION &UNCTIONS  4HE RELATION BETWEEN APERTURE ILLUMINATION AND THE  FAR 
 This corresponds toaFelative humidity of66per cent atatemperature of18°C, forexample. Over the range ofabsolute humidities normally encountered inthe atmosphere one may assume that the attenuation issimply proportional tothe absolute humidity. The rapid rise ofthe curve below 3mm isevidence ofthe powerful absorption displayed bywater vapor throughout the farinfrared. 
 Studies have shown that this argument is not neces - sarily valid when advanced adaptive spatial and temporal processing techniques are  employed because interference rejection efficacy is enhanced by higher interference- to-internal noise ratios. It has been widely argued that the inevitability of time-varying polarization trans - formation in the course of ionospheric propagation greatly reduces the possible utility  of being able to measure the polarization state of the signals arriving at the receiving  array. This is an open question at this time, though experiments aimed at assessing  skywave radar polarimetry are underway.116 Receivers. 
 Therefore small disturbances such as  screws and rivets on the surface of the re!lector will have little elTect on the antenna  rndiation rattern.  3. ;\11 increase i11 rrequency increases both the phase errors and the correlafio11 interval in  terms of wavelengths. 
 38. MacWilliams, F. J., and N. 
 8 Velocity-Azimuth-Display geometry for  measuring horizontal wind with a single doppler radar.  Measurement of the radial velocity for a complete azimuthal  scan (b) at elevation angle a permits an estimate of the  vertical profile of horizontal winds. ( Courtesy of University  Corporation for Atmospheric Research © 2007 , Boulder, CO ) ch19.indd   32 12/20/07   5:39:12 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Hehas aconsole patchboard bywhich hecan communicate with any of the operators, maintenance men, tellers, orplotters. Infront ofthe plotting board isafilter officer who decides which plots aretobetold to theFCC. The large vertical plotting board isshown inmore detail inFig. 
 The relationship between Z and snowfall rate r is as given by Eq. (1 3.20) for rain, but  with different constants a and b. There have been less measurements of the 2-r relationship for  snow than for rain, and there have been several different values proposed for the constants u  and b. 
 In a military radar, the coding can be changed to help  counter repeater jammers that attempt to simulate the waveform. The chirp waveform is more  vulnerable to repeater jamming than is the phase-coded pulse. The chirp waveform is n~ore  likely to be used when a wide bandwidth, or very narrow compressed pulse, is required. 
 Clutter signals from long ranges have both AM and FM noise that is essentially decorrelated, and feedthrough nulling of these signals may increase their deviation by a factor of 2 or their power by a factor of 4. See Eq. (14.3). 
 C. Goutelard, “STUDIO father of NOSTRADAMUS. Some considerations on the limits  of detection possibilities of HF radars,” Int. 
 Another benefit of . 528 INTRODUCTION TO RADAR SYSTEMS  this mode is that the scene to be imaged is observed over a range of incidence angles which  averages the speckle and makes a smoother image.  Since the synthetic-aperture radar is coherent, the image produced will have speckle; i.e.,  there will be constructive and destructive interference which results in a "break up" of dis­ tributed scatterers. 
 0.2   0.6   2.3   3.5   6.7   9.0 11.9 0.45 .   0.2   1.2   2.1   3.3   5.8   7.7 0.50 .   0.6   1.1   1.8   3.0   3.6 0.55 . 
 02& RADAR AS A FUNCTION OF RADAR ALTITUDE AND THE RANGE OF THE INTERSECTION OF THE PEAK OF THE MAIN 
 CIVIL MARINE RADAR  22.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 FIGURE 22.4  Ice feature detection using IIR filtering on Rutter Sigma 6 radar processor ( Courtesy of Transport Canada ) ch22.indd   15 12/17/07   3:02:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 
 POWER BEAMWIDTH  AND  N  IS THE NUMBER OF HITS PER BEAMWIDTH 4HE APPROXIMATION  PA y KA IS REPRESENTATIVE OF  AN ANTENNA DISTRIBUTION YIELDING ACCEPTABLE SIDELOBE LEVELS )T CAN BE SEEN THAT THE ANTENNA PATTERN PULSE 
 Results and Discussions In this section, experiments are carried out to evaluate the performance of the proposed method. Besides, the comparison with other methods indicates the outperformance of the proposed method. We will discuss the results after our experiments. 
 RIAL OF THE TARGET AND ITS SURROUNDINGS '02 IS VULNERABLE TO EXTREMELY HIGH LEVELS OF CLUTTER AT SHORT RANGES AND THIS  RATHER THAN SIGNALNOISE RECOVERY  IS ITS MAJOR TECHNICAL CHALLENGE 4HE SYSTEM TO BE SPECIFIED SHOULD TAKE THIS INTO ACCOUNT !LL THESE ASPECTS POSE SPECIAL DESIGN PROBLEMS FOR '02  WHICH IS DESCRIBED IN DETAIL BY $ANIELS  4HIS  CHAPTER IS A SUMMARY OF THAT MATERIAL AND IS REFERENCED BY COURTESY OF THE )%% ! TYPICAL '02 SYSTEM IS SHOWN IN &IGURE  AND CONSISTS OF A PAIR OF ANTENNAS   ONE FOR TRANSMIT AND ONE FOR RECEIVE  CONNECTED TO THE TRANSMITTER RECEIVER AND PROCES 
 #7 SCATTEROMETER 2& SECTION &)'52%     "ASIC BLOCK DIAGRAM OF AN &- 
 E.: Complementary Series, IRE Trans., vol. IT-7, pp. 82-87, April, 1961. 
 The transmitting-antenna gain and receiving-antenna aperture are functions of the  elevation and azimuth angles:  Gt = Gt(q, f)   Ar = Ar(q, f) (16.2 a) The differential scattering cross section itself is a function of both look angle  (q, f)  and ground location:  s 0 = s 0 (q, f, location ) (16.2 b) The integral of Eq. 16.1 must be inverted when s 0 is measured. With narrow beams  and short pulses, the inversion is relatively easy, but with the wider beams and lon - ger pulses used in many measurements, the values obtained are sometimes poorly  defined. 
 A compromise usually  niilst be made between good sniootliing of the random measurement errors (requiring narrow  haridwidtll) arid rapid response to marieuverir~g targets (requiring wide bandwidth). Another  criterion for selecting the a-fl coefficients is based on the best linear track fitted to the radar  data in a least squares sense. This gives the values of a and fl asT4  where rl is the number of the scan or target observation (n > 2). 
 W. Bordner: Synthesis of an Optimal Set of Radar Track-While-Scan Smooth-  ing Equations, IRE Trans., vol. AC-7, pp. 
   3TANFORD  5NIVERSITY  *UNE   * 4 ,YNCH  h!PERTURE SYNTHESIS FOR (& RADIO SIGNALS PROPAGATED VIA THE & 
 TIONS ARE ASSUMED 0RACTITIONERS IN THE FIELD OF RADAR METEOROLOGY OFTEN USE  :E AND :  INTERCHANGEABLY  ALBEIT INCORRECTLY !NOTHER FACTOR WE HAVE IGNORED IN THE DERIVATION OF THE RADAR EQUATION IS ATTENUA 
 Geophys.  Res., vol. 91(C11), pp. 
 85. D. R. 
 16. , ari ;ilgor.itll~il is available tllat requires approximately (N/2) log2 N multiplications  i~lstc.;~rl of (N 1 )2, wl~icli I.CSIIIIS ill ;I cotlsic!c~-able saving it1 processi~ig tirnc. This is tlie,jirst  I.'orrr.ic~r trtrrrs/or-~,r (1-f:'I'), wllicll tias bee11 widely described in the literature.".27 29  Sirice cacll filtcr occi~pies approximately 1/Nth the bandwidth of a delay-line canceler, its  signal-to-~loisc ratio will be greater than tliat of a delay-line canceler. 
 A ten to one hetr~~l  splitting would not be unusual for a typical radar. Some radars can measure angular accuracy  considerably better than this. An rms error of 0.1 mrad is possible with the best tracking  radars. 
   2!$!2 2%#%)6%23   È°Ó 2ANGE 3IDELOBES  %RRORS IN FILTER RESPONSES CAN PRODUCE DEGRADATION IN PULSE  COMPRESSION RANGE SIDELOBES 4HE EFFECT OF A FILTER RESPONSE ON RANGE OR TIME SIDELOBES  CAN BE SEEN BY TAKING THE FILTER IMPULSE RESPONSE  HT  AND ADDING TO THIS A DELAYED  IMPULSE RESPONSE LOG@  D" BELOW THE MAIN RESPONSE TO PRODUCE THE MODIFIED  RESPONSE HgT   WHICH IS GIVEN BY   HgT    HT    @  HT 
 The target lies well outside the clutter region where the Bragg lines are clearly visible, so  the signal-to-noise ratio, not the signal-to-clutter ratio, determines detectability. Note the ~10 dB variation  in target echo strength due to changes in the ionosphere over 128 seconds. ch20.indd   50 12/21/07   10:43:54 AMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Since acoustic waves travel with a speed about 10-s that of electromagnetic waves, an  acoustic line can be of practical size whereas an electromagnetic delay is not. However,  acoustic delay lines are larger and heavier than digital lines and must usually be kept in a  temperature-controlled environment to prevent unwanted changes in delay time. They  typically operate at frequencies from 5 to 60 MHz. 
 BEAM AREA ! SECOND CONCEPT USES TWO BEAMS AND TWO 230S STEP 
 29.  84. F. 
 ,,.,envelope  K detector  '°[ _L 5o 2 _ _,_.___....,,_._ _ _,_...___  999  998  995 ·  99  98  95 - 90  80  70  60 - 50  40 - 30  20  10  5 -4 6 8 10 12 14  Signal/ median clulter (dB)  (o)  ·,----- T  Rayleigh Che mo ff  hneor bound  detec!or line or  envelope  defector  Median  detector  Log  envelope  detec:lor 16 18  2 4 6 8 10 12 14 16 18 20  Signo1 I median cluller (dB}  (b) RADAR CLUTTER 487  Figure 13.7 Comparison of various  detectors in (a) log-normal clutter  with a mean-to-median ratio of 1  dB, a== 0.693 and (b) Weibull  clutter with a = 1.2 in Eq. ( 13. I 2 ). 
 /4( RADAR PERFORMANCE RESULTS v .AVAL 2ES ,AB 4ECH 2EPT  .2,-2 
 TIME ADAPTIVE PROCESSING FOR BISTATIC AIRBORNE -4) SEE 3ECTION    (OWEVER  TWO PROB 
 The two-way doppler shift is given by fd = (2VR/\) cos v|/0, where X is the radar wavelength, VR is the radar platform velocity, and i|/0 isRadar application Airborne or spaceborne surveillance Airborne interceptor or fire control Ground-based surveillance Battlefield surveillance (slow-moving tar- get detection) Missile seeker Ground-based weapon control Meteorological Missile warningRequirements Long detection range; accurate range data Medium detection range; accurate range, velocity data Medium detection range; accurate range data Medium detection range; accurate range, velocity data May not need true range information Short range; accurate range, velocity data High velocity and range data resolution Short detection range; very low false- alarm rate MTI- low PRF PD- medium PRF PD- high PRFAdvantages Can sort clutter from targets on basis of range. No range ghosts. Front-end STC sup- presses sidelobe detections and reduces dynamic range requirements. 
 PROPAGATION OF RADAR WAVES 445  .,  0 on  : 0 6  9 u .,  ~ () ~l  0  '" 0 4  0  J  ()?  () I ·f!o,,znnfol  · r,olorl1otion  Ver !,col  rflfl}t 1/0l·~fl •  0 L~-'-~.J--~'----'-~-' ,~ ., 160  ~ 140  C: ., Hor i1onlol polorirnt,on  ~ 120 :,-Vertical polori rnfion .,  8  g 100  V  ~  ~ 80  0  :;: nO  £'  Q 3.00() MHl'  100 MH;  0 10 20 30 40 50 60 70 80 90 10 20 30 40 so 60 10 ao 90  Groz,nq onqlr. rleq  (al Gro11ng angle, deg  (b)  Figure 12.J (<1) Magnitude of the rellection coefficient as a function of the grazing angle (for sea­ water). (h) Phase of the rellection coefficient as a function of the grazing angle (for seawater). 
 670 MOVINGTARGET INDICATION [SEC. 16.18 The end cell shown inFig. 16.10 ishighly efficient asanacoustic absorber butisuseless outside ofthelaboratory because theunsupported quartz plate canbecracked bystanding theline onend. 
 Theprocess isequivalent tothecomputa­ 1iOltoradiscrete Fourit'r trails/in.",. Ilowever, whenNisSOIllCpowerof2,thatis,N=2,4,H. 16.....analgorithm isavailable thatrequires approximately (N/2)log2Nmultiplications insteadof(NI)1.whichresultsinaconsiderable savinginprocessing time.Thisisthe/lISt Four;('/' tl'll/ls/im" (FFT),whichhasbecnwidelydescribed intheliterature.ll.n29 Sinceeachfilteroccupies approximately l/Nththebandwidth ofadelay-line canceler, its signal-to-noise ratiowillbegreaterthanthatofadelay-line canceler. 
 B.: The Nature of Doppler Velocity Measurement, IRE Trans., vol. ANE-4, pp. 103-112,  September. 
 The value of the frequency  excursion is then a measure of the altitude and may be substituted into Eq. (3.1 1).  When used in the FM altimeter, the technique of servo-controlling the frequency excirr-  sion is usually applied at all altitudes above a predetermined minimum. 
 The aim of  the consideration is to minimize the sum of reflections through the existence of two or more layered reflection locations.  Today in optics these procedures are commonly applied.  It is assumed that:   The wavelength is known,   The wave incidence takes place at a defined angle. 
 J. Dodds, T. Moreno, and W. 
 AllT Rudiutioti  Laboratory Rttpt. 1024, April. 1946. 
 DUCTOR TECHNOLOGIES %ACH 42 CHANNEL HAS SELF 
             
 In cross wind directions, with the radar looking along the troughs of the major waves, a much milder shadowing function will apply; so there should be a clear distinction between the upwind-downwind and crosswind behavior of sea clutter at very low grazing angles. Examples of clutter behavior at these angles may be found in independent measurements at relatively high wind speeds by Hunter and Senior off the south coast of England39 and by Sittrop off the west coast of Norway.40 Their results for orthogonal directions relative to the wind are shown in Fig. 13.13, along with the predictions of a conventional shadowing function41 and the threshold-shadowing function.38 It would appear that a combination of con- ventional shadowing (which goes as the first power of the grazing angle) across the wind and threshold shadowing in upwind and downwind directions accounts for the observed behavior of this very low angle clutter quite well. 
 Orthogonal circular-polarization components can also be used  to describe the polarization matrix. By transmitting two orthogonal polarizations and measur­ ing the amplitude and phase of the received echoes on each polarization, as well as the  cross-polarization component, a means of target discrimination, or classification, can be  provided. Some information about the target can be obtained from the amplitude only, and  not the phase, of the· polarization components. 
 Ifthesame antenna isusedforbothtransmitting andreceiving, theantenna isnotresponsive tothe opposite senseofrotation andtheechoenergywillnotappearatthereceiver. Atargetsuchas anaircraft, however, willreturnsomeenergywiththecorrectpolarization aswellasenergy withtheincorrect polarization. Energyincident ontheaircraft maybereturned afterone "bounce," asfromaplanesheetorasrherical surface; oritmightmaketwoormorebounces between variousportions ofthetarget(similar toacornerreflector) beforebeingreturned to theradar.Oneachbounce thedirection ofpolarization rotation isreversed. 
 Thesetechniques providesomeadvantage inthisregardbutthey canresultinundesired coupling between theazimuth andelevation channels andalossin signal-to-noise ratio. Themonopulse antenna mustgenerate asumpatternwithhighefficiency (maximum boresight gain).andadifference patternwithalargevalueofslopeatthecrossover oftheoffset beams.Furthermore, thesidelobes ofboththesumandthedifference patterns mustbelow. Theantenna mustbecapableofthedesiredbandwidth, andthepatterns musthavethedesired polarization characteristics. 
 WAY LOSSES ALONG THE PATH   TRAVERSED  INCLUDING IONOSPHERIC ABSORPTION AND GROUND 
 3X. K;tt7. I.. 
 Increased reproducibility: Circuitry that is batch-processed or circuits that originate from the same wafer exhibit consistent electrical characteristics from component to component. 4. Small size and weight: Integration of active and passive components onto a single chip results in high-density circuitry with multiple functions on a single chip. 
 Spatio-temporal evolution of accumulated subsidence in Wuhan city derived from Radarsat-2 images. Only 6 of the 20 subsidence maps are shown. 219. 
 Ê,,9Ê-9-/ 
 Phys., vol. 17, pp. 940-971, November,  1946. 
 The error-signal  slope as a function of the squint angle or beam crossover is shown in Fig. 5.1 1 The maximun~  slope occurs at a beam crossover of about 1.1 dB.  Automatic gain control (AGC) is required in order to maintain a stable closed-loop servo  system for angle tracking.'s2 The AGC in a monopulse radar IS accompllslled by ernploylng a  voltage proportional to the sum-channel IF output to control the gain of all three rcccivcr  channels. 
 These are combined into a beam -forming network of the type that form c ir- cularly polarized sum and difference patterns.  . Radar System Engineering  Chapter 12 – Selected Radar Applications  137        Figure 13.2  Two-channel monopulse antenna system. 
 OF 
 These comments are elaborated in Section 18.3. As discussed in several chapters of this book, the performance of doppler-sensitive  radars is conditional upon the velocity of their host platform. The velocity of a space - craft in orbit at altitude h above a planet of radius RP and mass MP is given by  V M G R hP P SC= + / ( ) (18.1) *  Nadir  is the point below the spacecraft on the surface intersected by the radius vector from the Earth’s center to  the spacecraft. 
 B., and P. D. L. 
 /75. 76. 77. 
 M. Shimada and A. Freeman, “A technique for measurement of spaceborne SAR antenna  patterns using distributed targets,” IEEE Transactions on Geoscience and Remote Sensing ,  vol. 
 If the quantity p(x,y,z) represents the reflectivity of the terrain being mapped, the signal received by a radar system can be described by *W = f f ff>(x,y,z)f\t - —} dx dy dz (21.17)JJJ L CJ The integration extends over the illuminated patch, and R is the range between a point (x,y,z) on the ground and the radar position (v/,0,/z). This equation shows that the received signal is the superposition of a large number of reflections . within the illuminated pattern of the antenna and within the range gate which ar- rive simultaneously at the radar antenna. 
 2.3) is 40,000GD ^ ^- (6.6) ^az^el where Baz and Z?e, are the principal-plane azimuth and elevation half-power beamwidths (in degrees), respectively. This relationship is equivalent to a 1° by 1° pencil beam having a directivity of 46 dB. From this basic combination, the ap- proximate directivities of other antennas can be quickly derived: for example, a 1° by 2° beam corresponds to a directivity of 43 dB because doubling one beamwidth corresponds to a 3 dB reduction in directivity. 
 H. Stiles and  F . T. 
 STATE !LTHOUGH ANY OF THE 2& POWER SOURCES MENTIONED HERE COULD BE USED IN FUTURE  RADAR SYSTEMS  IT SEEMS LIKELY THAT THE LINEAR 
 W. P.. and T. 
 53. Marshall, J. S., and W. 
 Ducoff  Byron W. Tietjen Lockheed Martin MS2 8.1 INTRODUCTIO N* A pulse compression radar transmits a long pulse with pulsewidth T and peak power  Pt, which is coded using frequency or phase modulation to achieve a bandwidth   B that is large compared to that of an uncoded pulse with the same duration.1 The  transmit pulsewidth is chosen to achieve the single-pulse transmit energy, given  by Et1 = PtT, that is required for target detection or tracking. The received echo  is processed using a pulse compression filter to yield a narrow compressed pulse  response with a mainlobe width of approximately 1/B that does not depend on the  duration of the transmitted pulse. 
 C'.. A. P. 
 In Section 12.3, reflector architectures are discussed and compared, and  in Section 12.6, mechanical and environmental design considerations are addressed. Chapter Synopsis.  The balance of this chapter is divided into five sections. 
 F. Yuen, “Study of SAW pulse compression using 5×5  Barker codes with quadriphase IDT geometries,” 1988 IEEE Ultrasonics Symposium , pp. 219–222. 
 10ne exception tothis statement should bementioned. Inana-cresonance charge modulator, thegenerator must produce agood sinewave.. ...0.9 P~- 860-’CPS CFover 2FF1.24Full load 800 CpS CF 1.40 FF1.09Fullloadwithchokeinput PS0.9PF 800 CPS CF1.47FF1.12 Chok~input PS114load 0.9PF1200CPS CFover2FF1.19Fullload1.0PF 1200Cps CF1.47FF1.11FullIoaclwithchokeinput PS0.9PF1200CPS CF 1,62FF1.14 ChokeinputPS1/4load 0.9PF1600CIM CF1.86FF1.15Full load1.0PF 1600CPS CF1.45FF1.09Fulllo-dwithchokainput PS0,9PF1600CPS CF1.59FF1.12 FIC+.14.I.—Voltage wave shape ofEclipse NEA-6 generator. 
 According to Nathan~on,'~ the discrete frequency-shift waveforms are preferable instead  of linear FM when the pulse-compression ratio and the signal bandwidth are large. The  resulting thumbtack ambiguity diagram means there will be no rangedoppler coupling to  cause erroneous measurements. The order in which the discrete frequencies are transmitted  can be varied so that each radar can have its own code, and interference between radars will be  reduced. 
 The shorter the pulse the more informa-  tion there is available from the radar, and therefore the greater will be the demands on the  information processing and display. In some high-resolution radars the number of resolution  cells might 6e greater than the capability of conventional displays to present the information  without overlap, so that a collapsing loss can result. The wide bandwidth might also mean less  dynamic range in some radar designs. 
 7)—-a sudden  increase in voltage, maintained at a steady higher value  for a certain time, then dropped almost instantaneously  to zero. Let us say that the time interval is 50 micro-  seconds, and that such a series of pulses be applied across  the differentiating circuit just examined. The sudden  . 
 Therefore, in this basic radar system theupper portion of the waveguide, including the feedhorn, and the reﬂector areconstructed so that they can be rotated in the horizontal plane by a drivemotor. This rotatable antenna and reﬂector assembly is called theSCANNER. Figure1.16illustratesaSLOTTEDWAVEGUIDEANTENNAandnotice that there is no reﬂector or feedhorn. 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.516x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 noise jammer leading to a JNR in the raw data of about 30 dB when the jammer  passes the center of the main beam, is depicted. The de-jammed image by adap - tive spatial suppression is also shown demonstrating the good performance of  adaptive spatial cancellation. 
 SPOTTED CUCUMBER BEETLE       #ONVERGENT LADY BEETLE       3PIDER UNIDENTIFIED       ./4%  /RIGINAL VALUES REPORTED IN SQUARE CENTIMETERS HAVE BEEN CONVERTED HERE TO D"SM  WHICH IS DECIBELS  RELATIVE TO A SQUARE METER4!",%  -EASURED )NSECT 2#3 AT  '(Z &)'52%    3AMPLE OF MEASURED 2#3 OF INSECTS  AS A FUNCTION OF INSECT MASS AT  '(Z  BASED ON 2ILEYS  SUMMARY 4HE DASHED LINE IS THE CALCULATED 2#3 OF WATER DROPLETS FOR COMPARISON AFTER * 2 2ILEY  Ú )%%%   . 
 The screen voltage issetatsuch a value that thetube draws approximately 10maofcurrent with nosignal; this puts 1volt across the 100-ohm line. N“egative signals from the detector may drive thegrid tocutoff, thereby reducing the cathode volt- age tozero. The video signals atthe cathode are then negative and limited to1volt inamplitude. 
 Th us a single, short-du rat ion current pulse sets l he  phase. Continuous application of drive power is not needed as in other phase shifters. A  ··square" hysteresis loop is desired for such a phase shifter. 
 To prove this statement the range compressing will be illustrated assuming that the frequency diﬀerence between channels, Δftends to zero. It allows discrete time and continuous frequency approach to be applied in the ISAR signal’s range compressing. The range compressed signal can be expressed as a frequency integration of a pulsar ISAR signal, i.e., ˆS(k,p)=fc+ΔF 2⎭integraldisplay fc−ΔF 2⎭summationdisplay g∈G⎭tildewideag[ˆtg(p)]·exp⎭bracketleftBig j·2π·f·ˆtg(p)⎭bracketrightBig df, (8) where⎭tildewideag[ˆtg(p)] = ag·rect⎭parenleftbiggˆtg(p) T⎭parenrightbigg exp⎭bracketleftBigg −2·[ˆtg(p)]2 T2⎭bracketrightBigg is the time dependent amplitude ,fc=f0+(ΔF/2)is the central channel frequency, ΔF=R.Δfis the frequency bandwidth. 
 LIMITED IE  CLUTTER 
 "ASED?2ADAR HTTPWWWASTRONAUTIXCOMCRAFTPRIRODAHTM HTTPWWWJPLNASAGOVSRTM HTTPENVISATESAINTOBJECTINDEXCFM FOBJECTID  HTTPWWWSPACECOMSPACENEWSARCHIVESPYARCH?HTML HTTPWWWEORCJAXAJP!,/3ABOUTPALSARHTM HTTPWWWSINODEFENCECOMSTRATEGICSPACECRAFTJIANBINGASP HTTPWWWCAFDLRDETSXSTART?ENHTM HTTPWWWSPACEGCCAASCENGSATELLITESRADARSATINF?OVERASP HTTPDIRECTORYEOPORTALORGPRES?#/3-/3KY-ED#ONSTELLATIONOF3!23ATELLITESHTML HTTPWWWIAICOIL$EFAULTASPX DOC)$ &OLDER)$ LANG ENRES POS   HTTPWWWNPOMASHRUSPACEENSPACEHTM  HTTPWWWEOHANDBOOKCOMEOHBPDFSMISSIONS?ALPHABETICALPDFSEARCH  #HINA(* 
 If the two waves arrive together out of phase, they  destructively interfere, and the resultant field strength is weakened. As the geometry of the transmitter and receiver change, the relative lengths of the  direct path and reflected path also change, which results in the direct and reflected  wave arriving at the receiver in varying amounts of phase difference. The received sig - nal strength, which is the vector sum of the signal strengths of the direct and reflected  wave, may vary up to 6 dB above and 20 dB or more below the free-space value. 
 The value of the aspect entropy helps us to analyze the scattering anisotropy of the CSAR image. At the pixel level, aspect entropy can discriminate isotropic and anisotropicscattering. At the target level, it can discriminate different types of targets from each other. 
 The Class- AB operated amplifier is biased just above 50% conduction using a trickle quiescent  current and is also commonly used as a push-pull amplifier. Class-C amplifiers are  biased such that conducting current in the transistor flows for less than 50% of the  incident input voltage signal. This allows for the highest efficiency at the expense  of power gain and with the highest level of nonlinear operation. 
 Burgers, J.M. A mathematical model illustrating the theory of turbulence. Adv. 
 Chapron, “A semiempirical model of the normal - ized radar cross-section of the sea surface 1. Background model,” J. Geophys. 
 37,  rp. 770-777. July, 1949. 
 VI are more straightforward as they both operated at the same frequency, with similar antennas and radar waveforms. In respect of detection performance,ASV Mk. VI principally differed from ASV Mk. 
 IEEE T rans. Aerosp. Electron. 
 TARGET INDICATORS  AND  SYNTHETIC 
 (4.21), except that the power spectrum W,(f) describing the spectrum  produced by tpe finite time on target is used. The clutter attenuation is  where H(f) is the frequency response function of the MTI signal processor. If the antenna  main-beam pattern is approximated by the gaussian shape, the spectriim will also be gaussian. 
 J. Alter: Automatic Detection and  Integrated Tracking System, Record of the IEEE 1975 International Radar Conference, pp. 391-395,  IEEE Publication 75 CHO 938-1 AES. 
 Khwaja, A.; Ferro-Famil, L.; Pottier, E. Efﬁcient SAR raw data generation for anisotropic urban scenes based on inverse processing. IEEE Geosci. 
 Harrys, “On the use of windows for harmonic analysis with the Discrete Fourier Transform,”  Proc. IEEE , vol. 66, pp. 
 For a single sensor on each sat- ellite with no grazing-angle limitations, a constellation of six satellites can pro- vide the required continuous coverage from polar orbits. The satellites would be equally distributed in two orbital planes, using the study results given by Harney.28 However, if the sensor in the SBR was limited to grazing angles be- tween 3 and 60°, then the required coverage could be provided by a constellation of 10 satellites. This constellation consists of 1 satellite in each of 10 equally spaced orbit planes at an inclination of 49.4°, resembling the Walker 10/10/8 constellation. 
 Lucas, S. McCammon, R. Hanson, and J. 
 L. Waruszewski, Jr., “Apparatus and Method for an Aircraft Navigation System Having  Improved Mission Management and Survivability Capabilities,” U.S. Patent 5,086,396,  2/4/1992. 
 16–28, 1955. 70. T. 
 In this prediction, SNR in decibels is plotted as a function of operating frequency and great-circle time delay or ground range. The numbers just above the abscissa (at 1-ms delay) are the noise powers in decibels below 1 W/Hz. For this plot the UTC time is 1800, SSN = 50, Pt = 200 kW, GtGr = 50 dB, T = 1 s, and a = 20 dBsm. 
 To obtain the gain of the array, it is necessary to sum all the different el- ement gains G^77(G). Thus G(0) = SG^(G) n Impedance Variation of Free Space. It is of interest to examine the case of a large continuous aperture which may be considered to be the limiting case of an array of many very small elements.57 The free-space impedance EIH varies as cos 0 for scanning in the E plane and as sec 9 for scanning in the H plane. 
 This is a much shorter pulse than is commonly  employed in radar. Although the required range-resolutions for a ground-based radar are  achievable in principle, it is usually not applicable in practice.  The use of frequency diversity, as described previously for reducing glint, can also reduce  the multipath tracking error. 
 Moore, “Resolution of vertical incidence radar return into random and specular compo - nents,” University of New Mexico, Eng. Exp. Sta., Albuquerque, 1957. 
 Sensors 2019 ,19, 2605 In a previous work, this stage was replaced by adaptive thresholding [ 32]. 2.5.2. Second Stage: Optical Flow Figure 4displays a 2CMV image after the ﬁrst stage wherein it is clear that additional processing is needed to improve results because the ridges of the building in both images are slightly misregistered and they are shown as changes in both images. 
 1, Naval Space Surveillance System,  Dahlgren, V A, July 1, 1976. 13. M. 
 III..1973. 71.Gunn,K.L.S.,andT.W.R.East:TheMicrowave Properties ofPrecipitation Particles. Quurt.J. 
 The possibility oftwo modes ofpropagation existing simultaneously inasingle lineleads toserious complications. The high- estpowers arebest transrnitted byFIG. 11.7.—Coaxial cable and matched type Nfittings. 
 17.3 isapplied tothecathodes of Va.and VW.Because ofthebias thetubes can conduct only during the coincidence oftheazimuth pulse with thepulses onthegrids. Condenser C,ischarged negatively bythesignal from v8b acting through diode VW and positively bythe signal from V%which forces negative charge to ground through Vg~. Ifthe coincidence time isequal onVSC and V%, the net result iszero. 
 The range at acquisition and the magnitude of the closing veloc- ity are such that the rendezvous-phase duration can be several minutes. A rea- sonably long period is essential to an accurate rendezvous, since sufficient time must be allowed for smoothing the inherently noisy radar tracking data as well as for correcting measured errors. A period of as much as 10 to 20 min is still short compared with the overall mission duration. 
 For small droop this loss is given by i r TT AK]2Fractional power loss = - TT^MTTT (17.18) where K^ = transmitter phase sensitivity (degrees phase change/percent voltage) AK/K = fractional voltage droop on modulator pulse Pulse-to-Pulse Random Modulation. In addition to the sinusoidal or narrowband-noise modulation, pulse-to-pulse random modulation may also be present. The predominant effect is clutter spreading noise into the detection filter. 
 BASED 3!2 FROM )SRAEL  4EC3!2 IS A FEATURED ELEMENT  OF THEIR NATIONAL SATELLITE TECHNOLOGY DEVELOPMENT PROGRAM  ,AUNCHED BY )NDIA   4EC3!2S NOMINAL STRIP 
 For example, ifpulse synchronization signals arereceived atalevel appreciably above that of interference, amplitude-selection methods can entirely exclude theinter- ference, regardless ofthetype ofmodulation. This gives theamplitude- modulation method adefinite advantage because the low duty ratio of the synchronization pulses makes itpossible totransmit them atpeak powers several times higher than the permissible averagel and thus assists these signals tooverride the interference. Afairly high ratio of peak toaverage power can also bemaintained forvideo signals since, except inextreme cases, echoes arereceived foronly asmall fraction ofthe time. 
 Mostradar receivers usedinconjunction withanoperator viewingaCRTdisplaymeetthiscondition and IFSecondVideo ~amplifier1-- r-----amplifier (BIt)detector(Bv)Figure2.3Envelope detector.. 24 INTRODUCTION TO RADAR SYSTEMS  may be considered envelope detectors. Either a square-law or a linear detector may be  assumed since the effect on the detection probability by assuming one instead of the other is  iisually small. 
 /\comparison orthenose-on crosssectionofseveralcone-shaped objectsisgiven inFig.2.13. Shaping orthetarget,aswiththecone-sphere, isagoodmethod forreducing theradar crosssection. Materials suchascarbon-fiber composites, whicharesometimes usedinaero­ spaceapplications, canfurtherreducetheradarcrosssectionoftargetsascompared withthat produced byhighlyreflecting metallic materials.62 Figure2.13Radarcrosssectionof asetof40°cones,double-backed cones, cone-spheres, double­ rounded cones,andcircularogives asafunction ofdiameter inwave­ lengths. 
 SURFACE MODE SUITE  FOR FIGHTER RADAR  AS SHOWN IN &IGURE  %ACH GENERAL CAT 
 WAVELENGTH TWO 
 PULSE FILTERS    . Ó°x{  2!$!2 (!.$"//+  THIS DICTATES THE LOCATION OF THE PEAK   THAT THE RESPONSE TO CHAFF AT  DOPPLER BE  DOWN  D"  AND THAT THE MISMATCH LOSS BE MINIMIZED -INIMIZING THE MISMATCH LOSS IS ACCOMPLISHED BY PERMITTING THE FILTER SIDELOBES BETWEEN  AND  TO RISE AS HIGH AS NEEDED LOWER SIDELOBES IN THIS RANGE INCREASE THE MISMATCH LOSS  4HE SECOND ZERO 
 Blake, L. V.: The Effective Number or Pulses Per Beamwidth for a Scanning Radar, Proc. IRE, vol. 
 SES OF THE  #LEMENTINE DATA FAILED TO REPRODUCE THE ORIGINAL RESULT    CONSIDERABLE  CONTROVERSY WAS GENERATED AS WELL $ISCOVERY ANDOR VERIFICATION OF POLAR ICE DEPOSITS ON THE -OON EMERGED AS A MAJOR OBJECTIVE OF .!3!S EXPLORATION PROGRAM   AND IF  PROVEN  WOULD BE AN ESSENTIAL RESOURCE FOR HABITABLE OUTPOSTS AT THE -OON 2ADAR %XPLORATION FOR 0LANETARY )CE   6OLUMETRIC ICE GIVES RISE TO TWO UNUSUAL  RADAR RESPONSES 7HEN ILLUMINATED BY A CIRCULARLY POLARIZED FIELD  THE PREDOMINANT BACKSCATTER FROM MOST NATURAL SURFACES HAS THE OPPOSITE SENSE OF CIRCULAR POLARIZATION )N THE CASE OF VOLUMETRIC ICE  HOWEVER  THE BACKSCATTER HAS THE SAME SENSE OF CIRCU 
 NOMENA CAN BE OBSERVED SUCH AS THE FREE SPACE PATH LOSS AND THE REDUCTION IN VELOCITY OF PROPAGATION IN THE GROUND )T SHOULD BE NOTED THAT THE  PROCESS OF PHYSICALLY SCANNING THE ANTENNA SYSTEM OVER  THE TARGET CREATES A HYPERBOLIC IMAGE OF THE TARGET  AS SHOWN IN &IGURE  &OR THE TWO 
 New York: McGraw-Hill, 1991. chap. 8, p. 
 BEAM AND SIDELOBE CLUTTER RETURNS OCCUR AT ZERO 
 H. Knittel (eds.), Artech House, Inc., Dedham, Mass., 1972, pp. 240-242. 
 MANCE HOWEVER  THE RELATIVE GROUP DELAY BETWEEN CHANNELS MUST BE TIGHTLY CONTROLLED OR COMPENSATED IN MONOPULSE  SIDELOBE CANCELER  AND DIGITAL BEAMFORMING SYSTEMS !LTHOUGH STOPBAND REJECTION IS CLEARLY A KEY PARAMETER  FILTERS WITH FAST ROLL 
 LEAVING AND TIMING 4HE ANSWER TO  WHAT IS PROVIDED BY TYPICAL WAVEFORM VARIATIONS  AND A FEW EXAMPLES 4HE EXAMPLES ARE NOT FROM ANY SINGLE RADAR BUT ARE A COMPOSITE OF MODERN RADARS 4HE GENERAL -&!2 IDEA IS ILLUSTRATED IN &IGURE  )T SHOWS TIME MULTIPLEXED OPERATIONS FOR AIR 
 In one embodiment of the phase-comparison principle as applied to missile g~~idance the  phase difference between the signals in two fixed antennas is measured with a servo-controlled  phase shifter located in one of the armsz7 The servo loop adjusts the phase sllifter ilntil 111e  difference in phase between the two channels is a null. The amount of phase shift which \\as to  be introduced to make a null signal is a measure of the angular error.  The phase- and amplitude-comparison principles can be combined in a single radar to  produce two-dimensional angle tracking with only two, rather than four, antenna beams.2B  The angle information in one plane (the azimuth) is obtained by two separate antennas placed  side by side as in a phase-comparison monopulse. 
 at  200 nmi. all targets below 8 km altitude arc beneath the radar line of sight and normally  would not be detected. Most commercial aircraft have a cross section greater than the 2 m2  specified for this radar. 
 80, no. 1,  January 1982. 46. 
 L. Herr and J. Williams (eds.), November 21,  1986, pp. 
 Theyseldomreporta detection thefirsttimeitisobserved, asisimpliedinthedefinition ofcumulative probability. Instead, thecriterion forreporting adetection mightbeathreshold crossing ontwosuccessive scans,orthreshold crossings ontwooutofthreescans,threeoutoffive,orsoforth.In track-while-scan radarsthemeasure ofperformance mightbetheprobability ofinitiating a targettrackratherthanacriterion basedondetection alone. Surveillance-radar rangeequation. 
 Schultz et al., “Measurement of the radar cross-section of a man,” Proc. IRE , vol. 46,  pp. 
 CLUTTER COHERENT AIRBORNE RADAR 4!##!2  4HIS  TECHNIQUE ATTEMPTS TO CENTER THE LARGEST RETURN FROM MAIN 
 U.S. Patent no. 2,624,876. 
 106.Konrad, T.G.:TheDynamics oftheConvective Process inClearAirasSeenbyRadar.J.Atm.Sci.• vol.27/pp.1138-1147, November. 1970. 107.Gossard, E.E..D.R.Jensen,andJ.H.Richter: AnAnalytical StudyofTropospheric Structure as SeenbyHigh-Resolution Radar,J.Atm.Sci.,vol.28.pp.794-807, July.1971. 
 CUITS THAT OBSERVE EACH RANGE INTERVAL TO DETERMINE WHICH INTERVAL HAS THE TARGET ECHO ! TYPICAL TECHNIQUE IS TO SET A VOLTAGE THRESHOLD SUFFICIENTLY HIGH TO PREVENT MOST  NOISE PEAKS FROM CROSSING THE THRESHOLD BUT SUFFICIENTLY LOW THAT A WEAK SIGNAL MAY CROSS !N OBSERVATION IS MADE AFTER EACH TRANSMITTER PULSE AS TO WHETHER  IN THE RANGE INTERVAL BEING EXAMINED  THE THRESHOLD HAS BEEN CROSSED 4HE INTEGRATION TIME ALLOWS THE RADAR TO MAKE THIS OBSERVATION SEVERAL TIMES BEFORE DECIDING IF THERE IS A TARGET PRESENT . 
 26.12 and LdB is the propaga - tion loss in dB as computed by APM. As a convenience for the radar engineer, AREPS  will also display the APM output in terms of propagation factor. Thus, Figure 26.15  displayed in terms of radar probability of detection as a percentage will appear as  shown in Figure 26.16 when displayed in terms of propagation factor . 
 ................................ ................................ ................................ 
 vol. /\FS-11. pp. 
 A. I. Leonov and K. 
 QUENCY OR THE GRAZING ANGLE  AT LEAST FOR ANGLES LESS THAN ABOUT  )N REVIEWING THE  RESULTS OF MEASUREMENTS AT FOUR FREQUENCIES5(&  ,  #  AND 8 BANDS6ALENZUELA AND ,AING  NOTED A RELATIVELY WEAK TENDENCY OF CLUTTER BANDWIDTH TO DECREASE WITH  INCREASES IN FREQUENCY BETWEEN THE 5(& AND 8 BANDS AND GRAZING ANGLES BETWEEN  AND  3INCE BOTH OF THESE VARIATIONS CAN LIKELY BE ACCOMPANIED BY A CHANGE IN THE SIZE OF THE RADAR FOOTPRINT ON THE SURFACE  THEY MIGHT BE DUE TO A DEPENDENCE ON RESOLU 
 1967.  54. Hatcher, J. 
 The detector output then contains anumber offrequencies, one corresponding toeach target range present. Preferably these fre- quencies are detected bysome device such asaFrahm vibrating-reed frequency meter, which indicates allfrequencies simultaneously. If, however, time isnoobject, adevice that scans the frequency range may beused. 
 The principle isidentical with that discussed inSec. 112 forthe outer conductor ofacoaxial rotary joint. The diameter ofthe radial section spreading out atright angles totherectangular tube ischosen so that the average oreffective distance from the inner surfaces ofthe waveguide isaquarter wavelength. 
 )& SIGNAL DIRECTLY (OWEVER  WHEN FASTER !$#S BECOME AVAILABLE  WHICH CAN ACCOMMODATE HIGHER ANALOG INPUT FREQUENCIES WHILE PROVIDING ADEQUATE 3.2 AND 3&$2  SYSTEMS WILL BE DESIGNED THAT SAMPLE THE 2& DIRECTLY  AS SHOWN IN &IGURE  !T THIS WRITING  !$# TECHNOLOGY ALLOWS DIRECT SAMPLING SYSTEMS WITH RESPECTABLE PERFOR 
 Rept. 248, Oct. 20,  1952. 
 52.Alday.J.R.:Microwave PlasmaBeamSweeping Array,IRETrans,vol.AP-IO.pp.96-97,January. 1962. 53.Pringle.D.H..andE.M.Bradley: SomeNewMicrowave Control ValvesEmploying theNegative GlowDischarge. 
 510  Conversion efficiency, 19 l  Conversion loss, mixer, 347  Cookie cutter tuner, 199  Corporate feed, 285  Correlation detection, 375-376  Correlation function, 373  Correlation time, sea echo, 484-485  Cosecant-squared antenna, 55-56, 258-261  Cosmic noise, 461  COSRO, 159  Coupled cavity TWT, 207  Coverage pattern, elevation, 446-447  Cross-correlation receiver, 375  Cross level, antenna, 273  Cross section (see radar cross section)  Cross talk, in tracking radar, I 58  Crossed-field amplifiers, 208-213  Crossed linear polarization, 506  Crowbar, for tube protection, 216  Crown-of-thorns tuner, 199  CRT screens, 355-357  Cumulative probability of detection, 64  CW radar, 68-81  CW wave-interference radar, 9  Data stabilization, antenna, 270  d-c operation, of CF A, 211  Decorrelation time, sea echo, 484-485  Decoy, 553  Delay-line canceler, 104, 106-114  Delay lines, pulse compression, 424-426 Delta-a scanner, 298  Density modulation. 213  Density taper, 332  Detection criteria, 376-382  with non-Rayleigh clutter, 485-486  Detector characteristics, 382-386  Dicke fix, 394, 549-550  Dielectric lenses, 248-250  Diffraction, it56-459  Digital phase shifters, 287 -288  Digital processing:  MTI. t 19-125  SAR, 526  Diode burnout. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter.  SEA CLUTTER  15.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 be added a wind-drift velocity of about 3% of U and a fixed scatterer  velocity (which  appears to be about 0.25 m/s in the X- and C-band measurements60,61,63). 
 WAVELENGTH  SINGLE 
 Type 301 was a horizontal quarter wave swept back at 45 °, mounted on the skin of the aircraft and covering 172 –189 Mc/s. The same aerials were used for both transmission and reception. Aerial type 184 was a vertical half-wave with a director on a streamlined spar which spaced it off from the aircraft skin. 
 3,5. The diffraction pattern ofasmall plate exhibits astrong maximum atanangle corresponding tothat for specular reflection, and atother angles fails offwith theoscillations shown. Ifthe plate iscovered with absorbing material ofhigh refractive index, theprincipal diffraction maximum isgreatly reduced whereas thesecond- ary maximum isingeneral only slightly changed. 
 1965.  115. Vitale. 
 The purposeofthedelayvoltageistoprovideareference fortheconstant outputsignalandpermit receivergainforweaksignals.Ifthedelayvoltagewerezero,anyoutputwhichmightappear fromthereceiverwouldbeduetothefailureoftheAGCcircuittoregulate completely. Inmanyapplications ofAGCthedelayvoltageisactually zero.Thisiscalledundelayed AGe.InsuchcasestheAGCcanstillperformsatisfactorily sincetheloopgainisusually(ow forsmallsignals.ThustheAGCwillnotregulateweaksignals.Theeffectissimilartohavinga delayvoltage,buttheperformance willnotbeasgood. Therequired dynamic rangeoftheAGCwilldependuponthevariation inrangeover whichtargetsaretrackedandthevariations expected inthetargetcrosssection.Iftherange variation were10to1,thecontribution tothedynamic rangewouldbe40dB.Thetarget crosssectionmightalsocontribute another 4O-dBvariation. 
 Brit.IRE,vol.17,pp.319-329, June,1957. 49.Skolnik M.I.,andD.G.Tucker: Discussion on"Detection ofPulseSignalsinNoise:Trace-to-Trace Correlation inVisualDisplays," J.Brit.IRE,vol.17,pp.705-706, December, 1957. 50.Payne-Scott, R.:TheVisibility ofSmallEchoes onRadarPPIDisplays, Proc.IRE,vol.36, pp.180-196. 
 Marcum, J. L: A Statistical Theory of Target Detection by Pulsed Radar, IRE Trans., vol. IT-6, pp. 
  
 VII 35 (max) +5.9Airborne Maritime Surveillance Radar, Volume 1 7-3. against Grassholm on an individual trial. The average normalised detection ranges against U-class submarines were also assessed and are shown in table 7.2. 
 Inamilitary radar,alow-noise receivercanmaketheradarmoresusceptible totheeffects ofdeliberate electronic countermeasures (ECM).Whenpractical. itmaybepreferred todelib­ eratelyemploy aconventional receiver withmodestsensitivity andtomakeupforthe reducedsensitivity bylargertransmitter power.Thisisnotthemosteconomical waytobuilda radar.butitdoesmakethetaskofthehostileECMdesigner moredifficult. Avarietyoflow-noise radarreceivers areavailable totheradarsystemdesigner. 
 Anglefluctuations affectalltracking radarswhether conical-scan, sequential-Iobing, ormonopulse. Consider arathersimplified modelofacomplex radartargetconsisting oftwoindepen­ dentisotropic scatterers separated byanangular distance 0IJ,asmeasured fromtheradar. Although suchatargetmaybefictitious andusedforreasonsofmathematical simplicity, it mightapproximate atargetsuchasasmallfighteraircraftwithwing-tip tanksortwoaircraft targetsflyinginformation andlocatedwithinthesameradarresolution cell.Itisalsoaclose approximation tothelow-angle tracking problem inwhichtheradarseesthetargetpillSits imagereflected fromthesurface.Thequalitative effectsoftargetglintmaybeassessed from thismodel.Therelativeamplitude ofthetwoscatterers isassumed tobea,andtherelative phasedifference isCt..Differences inphasemightbeduetodifferences inrangeortorel1ccting properties. 
 Frorri Eq. (8.3), E,(O) = E,(n - 0). Therefore an antenna of isotropic elements has a  siniilar pattern in the rear of the antenna as in the front. 
 Theantenna mayberotatedat constant rateshigherthanwouldbepractical withothermounts requiring application ofa correction foravariable platform-tilt. Thisthree-axis stablebaseantenna hasnoelevation angleandislimitedtoapplications whichscanthehorizonorafixedangleofelevation with respecttothehorizon.Ifelevation scanning athighratesisrequired, asinheightfindersor 3-Dradar,afourthaxiscanbesupplied asin(i).Thisconfiguration, although itrequires no computer. isrelatively massive andheavybecause ithasfourservosystems forcontrolling. 
 inMTI.1.10131 Errors: inarrayantcnnas. 31R322 inrcnector antennas. 262--264 rvaporation ducl,453455 F:llponcntial prohahility densityfunction. 
 The time difference between the forward-looking beam and the side-looking beam is Δt=LAB/v (5) The repetition frequency of the transmitted pulse is PRF and the data are received in the strip mode. For a same target, it is located at different azimuth sampling units, and the difference of azimuth sampling units between different beams is Δnan=Δt·PRF =LAB·PRF /v (6) The data of each beam are processed independently to obtain images. When fusing the images from different beams, it is necessary to ensure the matching of the position of the target. 
 If we wish to prevent range migration  (movement of a  point target from one range bin to the next during the time required to collect the data  for image formation), we would require that ∆R, the variation of range during the data  collection (over the synthetic aperture), be less than dr. We consider the formation of a SAR image after collecting data over an aperture  time tA. The SAR flight path is a straight line at constant speed and altitude over a flat  ground. 
 (8.18). Note that the beam position is not  symnletrical with frequency. To scan the beam +45" about broadside requires a bandwidth of  almost 30 percent with a wrap-up factor of 5, and 7 percent for a wrap-up factor of 20. 
 If the large echo is considerably stronger than the mean of the remaining contributors to the return, this approaches a normal distribution about the value for the large echo. In practice, the distribution from large targets may be more complicated than either of the simple models described. For reference, the two distributions are given:55 p(v)dv = — e~v2/2^dv (Rayleigh) *°p(v)dv = -^- e~(v2 + "2)/2*%( — |dv (sine wave + noise) v|;o1/2 Wo/ where v = envelope voltage v|>0 = mean square voltage a = sine-wave peak voltage IQ(X) = Bessel function, first kind, zero order, imaginary argument Fading-Rate Computations. 
 Radar Conf ., Alexandria (VA), USA,  May 9–12, 2005, pp. 663–668. 159. 
 IRE, vol. 34, pp. 828 836, November, 1946. 
 85-102. January, 1978.  95. 
 13) the connexions differ from the  usual pentode arrangement in two respects. First, the  suppressor grid G3 is connected to cathode (earth)  through a resistance R2, instead of the usual direct con-  nexion to cathode. The insertion of this resistance  allows G3 to take up varying potentials depending on the  other circuit conditions. 
 The effective two-way antenna patterns are  shown in Figure 2.100. As previously mentioned, the above techniques (STC, two-beam antennas, and  some variation of MTD) are currently used on many air-traffic-control radars. The  two-beam antennas also utilize some high-angle gain enhancement to counter the  high-angle effects of STC. 
 The lines ofcurrent flow inthe. 400 R-F COMPONENTS [SEC. 11.3 walls are also shown. 
 Estimates for noise power  spectral density are derived from CCIR Report 322-3, as described in Section 20.9.  In this prediction, SNR in decibels is plotted as a function of operating frequency and  great-circle time delay or ground range. The numbers just above the abscissa (at 1-ms  delay) are the noise powers in decibels below 1 W/Hz. 
 Simulated Experiment In order to verify the feasibility and accuracy for solving the aforementioned models, a simulated experiment was designed and implemented. The elastic modulus coe ﬃcient was set up by investigating the design materials and the structural morphology of the test highway. It was controlled within the interval [0, 50]MPa .The v iscosityηwas set within the interval [0, 8]×106Mpa. 
 THE ELECTRONICALLY STEERED PHASED ARRAY ANTENNA IN RADAR 337  been of considerable interest, but it can also be a serious liability in some applications. The  preferred frequency for a ground-based aircraft surveillance radar is al the lower portion of the  microwave region (UHF or L band). The major factors of importance that favor the lower  frequencies for surveillance radar are the large average power and the large antenna aperture. 
 Another approach that depends on additional antenna feeds, or degrees  of freedom, employs a monopulse tracker with a difference pattern containing a second null  wliicli is independently steerable. This null is maintained in the direction of the image, as  computed by Snell's law for the measured target range. The use of the classical maximum  likelihood solution for the optimum double-null difference pattern results in relatively large  sidelobes at the horizon and at angles below the image. 
 11309, 2004. 104. T. 
 TRACING TECHNIQUES FALL INTO TWO CATEGORIES ANALYTIC AND NUMERICAL !NALYTIC METH ODS ARE FAST BUT RELY ON FIT 
 NOISE RATIO IN THE RECEIVER WILL EXCEED THE IMPROVEMENT FACTOR LIMIT OF THE SYSTEM EVEN WHEN TECHNIQUES SUCH AS SENSITIVITY TIME CONTROL 34#   IMPROVED RADAR RESOLUTION  AND REDUCED ANTENNA GAIN CLOSE TO THE HORIZON ARE USED TO REDUCE THE LEVEL OF CLUTTER RETURNS 4HE RESULTING CLUTTER RESIDUES AFTER THE -4) CANCELER MUST  THEREFORE  BE FURTHER SUPPRESSED TO PREVENT SATURATION OF THE 00) DISPLAY ANDOR AN EXCESSIVE FALSE 
 157 CHAP. 6. THE GATHERING AND PRESENTATION OF RADAR DATA 160 6.1 Influence ofOperational Requirements. 
 S. A. Hovanessian, Introduction to Synthetic Array and Imaging Radars , Norwood, MA:  Artech House, 1980.FIGURE 17.16  Conventional and FOPEN SAR62 images: In the conventional image, target vehicles   cannot readily be seen, whereas in the FOPEN image they are quite prominent. 
 Line-type pulsers forradar applications have been built and operated successfully tocover arange ofpulse power output of1kwto20Mw. The following photographs show typical pulsers designed forairborne service. Figure 10.47 shows ahydrogen-thyratron pulser designed tosupply. 
 J. Dome, J. Sweet, and G. 
 BASED BACKSCATTER MEASUREMENTS OF THE SEA v  )%%%    * /CEANIC %NG  VOL /% 
 OUSLY COLLECTED COMPLEX IMAGES  SUCH THAT THE PHASES OF THE CORRESPONDING PIXELS IN THE FOUR IMAGES BEAR A SPECIFIC RELATIONSHIP TO EACH OTHER  DEPENDING ON THE TARGET TYPE .OVAK ET AL  DEVELOPED AN OPTIMAL  POLARIMETRIC WHITENING FILTER FOR ENHANCED TAR 
 1The pulses may beseparated from thevideo signals byamplitude selection, or bytime separation asinFig. 174.. SEC. 
 The basic theory for scattering from homogeneous and isotropic turbulent media was  first given by Tatarsk i.111 · 112 The scattering mechanism from turbulent media is similar to  Bragg scatter in that a radar of wavelength A. scatters from that particular component of the  turbulence with eddy sizes equal to ,l../2. The volume renectivity, or radar cross section (m2) per  cubic volume. 
 A receiver with a reactance input such as a parametric amplifier need not have any  significant ohmic loss. The limitation in this case is the thermal noise seen by the antemu. and  the ohmic losses in the transmission line. 
 An innovative methodological approach in the frame of Marine Strategy Framework Directive: A statistical model based on ship detection SAR data for monitoring programmes. Mar. Environ. 
 For small beamwidths, the doppler  frequency decreases linearly as the point-scatterer position changes relative to the radar and  goes to zero when the scatterer is at the center of the beam, after which the frequency increases.  The time-varying doppler frequency can be shown to be approximately'  where to is the time when the point scatterer is at the center of the beam, and H is the range to  the scatterer at that time. The total width Af, of this doppler signal as the scatterer progresses  through the beam is 2v2Td/AR, where & is the time during which the scatterer is within tlie  beam. 
 BEAM KLYSTRON 4HEY CAN ALSO HAVE REDUCED NOISE AND LESS PHASE SENSITIVITY TO DEVIATIONS IN VOLTAGE  WHICH AIDS IN THE  DETECTION OF LOW CROSS 
 75.Sekhon, R.S.,andR.C.Srivastava: SnowSizeSpectraandRadarReflectivity. J.Almos.Sci.,vol.27. pp.299-307, 1970. 
 Ideally the signal  applied to the antenna should be a Dirac function but practically it is more like a  skewed gaussian impulse of defined time duration. Most antennas used in surface  penetrating applications have a limited low frequency response and tend to act as  high-pass filters, effectively differentiating the applied impulse and hence creating a  time-limited function. In most cases, near identical antenna are used, and if these are  spaced sufficiently far from the ground surface, then saf(t) = sar(t). 
 West, “Numerical study of shadowing in electromagnetic scattering  from rough dielectric surfaces,” IEEE Tran. in Geosci. and Remote Sensing , vol. 
 = Ta+ Te= To Fs  where Fs is the system noise-figure including the effect of antenna temperature. (9.8)  The effective noise temperature of a receiver consisting of a number of networks m  cascade is  (9.9)  where ~ and Gi are the effective noise temperature and gain of the ith network.  The effective noise temperature and the noise figure both describe the same characteristic  of a network. 
 They can also be made to operate with  constant efficiency when shaping of the pulse amplitude is used to reduce interference  caused by its far-out spectrum, something not as practical to do with other types of  microwave tubes. Coaxitron.  The performance of conventional grid-control tubes at the higher fre - quencies is limited by the time it takes for the electrons to transit from the cathode to  the anode of the tube. 
 ELS HAVE SEPARATE VALUES OF THE CONSTANTS FOR  AND  4HE YEAR  WAS  VERY DRY IN +ANSAS THEREFORE  THE  VALUES ARE PROBABLY MORE REPRESENTATIVE  BUT BOTH ARE GIVEN HERE 6ALUES OF THE CONSTANTS ARE IN 4ABLE  &IGURE  SHOWS THE CLUTTER MODEL FOR THE MIDRANGE OF ANGLES AS A FUNCTION OF FREQUENCY  %Q 0OLARIZATION!NGULAR  2ANGE &REQUENCY 2ANGE  '(Z#ONSTANT  ! OR -  D"!NGLE 3LOPE " OR .  D"&REQUENCY 3LOPE #  D"'(Z3LOPE #ORRECTION $  D" ¾ '(Z  A6 n n  
 Since the rod of ferrite is located at the center of the guide out  of contact with the walls, there is no means for dissipation of heat other than by radiation. This  lack of a convenient thermal path to dissipate heat limits its power handling capability.  However, in one de~ign,~'-~* the heat transfer problem was overcome by having the axially  IIII'RITIRONI('AII.Y STHRI'D !'IIASED ARRAY ANTENNA INRADAR291 anohmwithtensofmilliamperes biascurrent. 
 Extensions  of this model into what might be called a three-scale model  are guided by the same  ideas that led to the two-scale model .72,106 An additional ad hoc spectral partition is  introduced between the longest and shortest wave components of the sea spectrum, but  this produced only modest improvement.106 ch15.indd   30 12/15/07   6:17:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter. 
 4.22a. Figure 4.22b shows the in-phase, or /, channel with the pulse train such  Doppler  frequency  ,....""' >'/ '\  I \  01 Oz /­ <I)  u I '\ ::, I \.  a. 
 When the ion oscillations appear, they  usually have a magnitude about 40 dB below the carrier, or else they are not mea~urable.~~ 1  Thus there is no need to specify a measurement of this noise to a level better than 40 dB below  the carrier to insure the required noise levels. Since ion oscillations may occur at some  combination of tube parameters and not at others, the CW radar tube should be tested for  noise-free operation over the expected range of beam voltage, heater voltage, RF drive level,  and load VSWR. Noise-free operation also requires well-filtered beam power-supplies and a  dc heater supply. 
 The tube is 76 cm long, 42 cm in  diameter and weiglis 63.5 kg.  Low-power grid-control tubes have been used in phased array radars at UHF and have  proven to be an economical arid reliable source of power. In the AN/FPS-85 satellite-  surveillance radar built by Beridix Corporation for the U.S. 
 The refocused results of ship02 are shown in Figure 7. The image quality of the proposed method result is also superior to the other results.      (a) (b)       (c) (d)  Figure 6. 
 13.24b accomplishes thesame results more simply. Figure 13.24 illustrates one-way clamps using asingle triode. 1In both cases the clamping isdone through the tube impedance asviewed from X. 
 41.Mortley, W.S..andS.N.Radcliffe: PulseCompression andSignalProcessing, IEEECorif.Publica­ tionNo.105,"Radar-Present andFuture:' Oct.23-25,1973,pp.292-296. 42.Bogotch, S.E.,andC.E.Cook:EffectsofLimiting ontheDetectability ofPartially TimeCoincident PulseCompression Signals,IEEETrans.,vol.MIL-9,pp.17-24,January, 1965. 43.Woerrlein, H.H.:Spurious TargetGeneration DuetoHardLimiting inPulseCompression Radars, IEEETrans.,vol.AES-7,pp.1170-1178, November, 1971. 
 If the FM-CW radar is used for sing1e targets only, such as in the radio altimeter, it is not  necessary to employ a 1inear modulation waveform. This is certainly advantageous since a  sinusoidal or almost sinusoidal frequency modulation is easier to obtain with practical equip­ ments than are linear modulations. The beat frequency obtained with sinusoidal modulation is  not constant over the modulation cycle as it is with linear modulation. 
  
 (1 1.34) is useful, however, as an indication of the accuracy with which  time delay and frequency may be measured simultaneously. The product of the rms time-  delay error [Eq. (1 1.17)] and ttie rrns frequency error [Eq. 
 IEEE S.E. Region 3 Conf , 1976, pp. 48–50. 
 Withaphasedarraydividedintotwo overlapping subarrays, aconstant pulserepetition frequency canbeusedandthehorizontal separation ofthetwooverlapping subarrays canbecontrolled electronically tocompensate for platform motion. However, itispossible tochangetheeffective phasecenterofarellector antenna byemploying twofeedstoproduce twosquinted overlapping beams,asinan amplitude-comparison monopulse radar(Sec.5.4).Theoutputsofthetwofeedsarecombined usingahybridjunction toproduce asumpattern1:andadifference pattern L\.Bytaking 1:±jkL\,theeffective phasecentercanbeshifteddepending onthevalueofk.(Thefactorj multiplying thedifference patternsignifies a90°phaseshiftaddedtothedifference signal relativetothesumsignal.)Theuseofthistechnique inanAMTIradartocompensate forthe effectsofplatform motioniscalledDPCA,whichstandsforDisplaced PhaseCenterAntenna. Thesumanddifference patterns canbeobtained byconnecting ahybridjunction tothe outputsofthetwoantenna feedsasdescribed inSec.5.4.Thesumpatternisusedo~transmit andboththesumandthedifference patterns areextracted onreceive.Thesignalreceived on thedifference patternisweighted bythefactork,shiftedinphaseby90°andisaddedtothe sum-pattern signalinthedelayedchannel andsubtracted fromthesum-pattern signalinthe undelayed channel. 
 FIGURE 9.1  (a) AN/FPQ-6 C-band monopulse precision tracking radar installation at the NASA  Wallops Island Station, VA. It has a 29-ft-diameter dish and a specified tracking precision of 0.05 mrad rms.   (b) AN/MPS-39 C-band electronic scan phased-array Multi Object Tracking Radar (MOTR) installed at  the White Sands Missile Range. 
 BANDWIDTH PRODUCT  4"   4IME SIDELOBE LEVEL  n D"4ARGET RANGE WINDOW  FT.UMBER OF RANGE SAMPLES 2ANGE SAMPLE SPACING  FT&IRST )& AT OUTPUT OF CORRELATION MIXER   -(Z3ECOND )&  -(Z 3TRETCH PROCESSING BANDWIDTH  " P   K(Z !$ CONVERTER SAMPLING FREQUENCY  -(Z IN ) AND 1 BASEBAND CHANNELS 4!",%    #OBRA $ANE 7IDEBAND 0ULSE #OMPRESSION 3YSTEM #HARACTERISTICS ADAPTED FROM &ILER  AND (ARTT Ú )%%%      %XCLUDES PULSEWIDTH AND SWEPT BANDWIDTH EXTENSION DUE TO  
 - 4HE PRIMARY OBJECTIVE OF %##- TECHNIQUES WHEN APPLIED TO A RADAR SYSTEM IS TO  ALLOW THE ACCOMPLISHMENT OF THE RADAR INTENDED MISSION WHILE COUNTERING THE EFFECTS OF THE ENEMYS %#- )N GREATER DETAIL  THE BENEFITS OF USING %##- TECHNIQUES MAY BE SUMMARIZED AS FOLLOWS   PREVENTION OF RADAR SATURATION    ENHANCEMENT OF THE SIGNAL 
 Wind speeds from 8 to 15 knots  produced ii low, moderately strong duct, and winds from 20 to 30 knots produced a higher,  but weaker duct. Passing squalls and rain showers did not wipe 0111 the duct or decrease  the propagated signals.  The thicker the duct. 
 517 . 518 INTRODUCTION TO RADAR SYSTEMS  ,,  Figure 14.l Geometry of the synthetic aperture radar  traveling with a velocity v. The radar transmits a pulse at  each position marked by an x. 
 At shorter ranges, the large solid angle that must be scanned in order to cover all regions of a storm requires total scanning times of the order of 3 to 5 min even for ideally situated storms. This is a consequence of the on-target time necessary for accurate radial velocity measurements. Finally, the storm itself is evolving and moving during this measurement time. 
 n   FOR RIGHT 
 17,  pp. 71–83, May 1985.  5. 
 Transmission Lines and Fittings,  ASESA. 49-28.} . 58 INTRODUCTION TO RADAR SYSTEMS  gas-tube duplexer also introduces loss when in the fired condition (arc loss); approximately  1 dB is typical. 
 i# <. :;c, I v3b 1Point E’~ (c) Deta(fs of’comparison circuitr FIQ. 17.13.—Tracking methods: (a) simple tracking methods; (b) circuit.regenerative trarking method; (c) details ofcomparison. 
 M. Bradley: Some New Microwave Control Valves Employing the Negative  Glow Discharge. J. 
 The resulting angular error persists until itismanually removed. When amplitude selection ofthe. Ehc. 
 MOVING VEHICLES HAVE FAST 
  
 The AN/TPS-59 was the  world’s first totally solid-state antenna/array. The AN/FPS-117 was developed shortly  thereafter and is typically installed and operated at a fixed site, but it can also be con - figured on a trailer for deployment. The AN/TPS-77 is a mobile/transportable series  of solid-state radar systems. 
 The Radar System Improvement  Program (RSIP) provides the most significant upgrade to the AWACS radar since its  development in the early 1970s. RSIP introduces new waveforms and processing,  providing improvements in detection range, angular accuracy, as well as range and  angular resolution. AN/TPS-78. 
 PULSE DOPPLER FILTER BANK  WHERE  7I ARE THE DOP 
 Studer, “A review of CFAR detection techniques in radar systems,”  Microwave Journal , pp. 115–128, September 1986. 143. 
 Calibration of the bombsight was done in advance on training runs with dummy bombs. The exact timing of bomb release was dependent on bomb type and airspeed. 4.3.3 Strobe control unit type 454 The strobe control unit is illustrated in ﬁgure 4.12. 
 Communication bytheInterrogation Link.—So far, methods ofinterro- gation coding have been discussed which determine whether ornot the beacon will reply when interrogated. More complicated schemes for coding theinterrogating beam enable thetransmission ofinformation to thevehicle carrying thebeacon. Such schemes areusually applied only incases where the interrogating antenna points continuously atthe beacon. 
 October, 1959, and pp. 33-38, November, 1959; also discussion  hy F. J. 
 Theprincipal advantage ofaCWdoppler radaroverother(nonradar) methods ofmeas­ uringspeedisthatthereneednotbeanyphysical contactwiththeobjectwhosespeedisbeing measured. Inindustry thishasbeenappliedtothemeasurement ofturbine-blade vibration, the peripheral speedofgrinding wheels,andthemonitoring ofvibrations inthecablesofsuspen­ sionbridges. - Mostoftheaboveapplications canbesatisfied withasimple,solid-state CWsourcewith powersinthetensofmilliwatts. 
 R. Forrest, “Principles of independent receivers for use with co- operative radar transmitters,” Radio Electron. Eng ., vol. 
 114 order toobtain amuch lower beat frequency which can beamplified. Amore complete and integrated discussion ofmicrowave receivers is reserved forthenext chapter, but forthesake ofcontinuity thecompo- nents ofthe receiver which handle microwaves aretreated here incon- junction with other r-fcomponents. 11.6. 
 On the other hand, fine  crossrange resolution requires multiple pulses, and the corresponding processing is,  therefore, often termed slow-time processing  (Carrara,3 Richards,24 and Klemm25). Range Resolution.  Strictly speaking, SAR refers to a method for improving  crossrange resolution, not range resolution. 
 MATE OF RADAR BIASES BETWEEN TWO RADARS CAN BE OBTAINED FROM A LONG 
 The peak transmitted power at S band is 1 MW and 50 kW at X band. The pulse widths are approximately 1 n,s, and the PRF is typically 1000 s"1. The system is characteristic of the technologies currently in place in the re- search community in this field. 
 This surface wave  is important because it can cause a large reflection (and an accompanying loss of the  beam) for some angles of scan. This can best be seen by examining the condition of  ch13.indd   24 12/17/07   2:39:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 BAND )NTER 
 48, pp. 663-669.  April, 1960. 
 BANDWIDTH PRODUCTS ARE TYPICALLY LESS SENSITIVE TO $$3 SPURIOUS SIGNALS SINCE THE $$3 SPURIOUS SIGNALS CHIRP AT A DIFFERENT RATE TO THAT OF THE WANTED SIGNAL 4HE SPURIOUS SIGNALS ARE THUS REJECTED DURING PULSE COMPRESSION )N PULSE DOPPLER APPLICATIONS  SPURIOUS  SIGNALS ARE OF MUCH GREATER CONCERN HOWEVER   THEIR EFFECTS CAN BE MITIGATED BY ENSURING THAT THE $$3 GENERATES EACH WAVEFORM FROM THE SAME INITIAL CONDITIONS 2ESTARTING THE $$3 FOR EVERY PULSE GUARANTEES THAT THE SAME DIGITAL SEQUENCE WILL BE INPUT TO THE $! CONVERTER FOR EACH PULSE 4HE RESULT IS A $$3 OUTPUT THAT ONLY CONTAINS SPECTRAL COMPONENTS AT MULTIPLES OF THE 02& 4ECHNIQUES HAVE BEEN PROPOSED OR INCORPORATED INTO $$3 DEVICES  THAT REDUCE SPU 
 TION 4HIS EXTENDS THE TIME SIGNATURE OF THE RADIATED WAVEFORM AND DEGRADES THE RANGE RESOLUTION OF THE SYSTEM 4HIS EFFECT IS SHOWN IN &IGURE  WHERE THE RADIATION PAT 
 12.6  Descriptions of a Surface  ...................................  12.6  Simplified M odels  ..............................................  12.7  Physical Optics Models  ...................................... 
  SYSTEM FAILURE !  HIGH 
 17.13 Filter improvement factor versus clutter width. If a clutter canceler is used, the output cannot begin to settle to steady-state value until space charging is complete. Some settling time must be allowed before signals are passed to the filter bank. 
 MEDIUM 
 N.: "Radar System Engineering," MIT Radiation Laboratory Series, vol. 1, McGraw-  Hill Book Co., New York, 1947.  13. 
 Therefore, the system improves the efﬁciency of data recording. An improved range migration algorithm (RMA) is used for data processing, and imaging is made in a uniﬁed imaging coordinate system. The resolution of different view images is the same, and there is a ﬁxed delay between the images. 
 This results from the nature of the noise voltage that is always present in the receiver circuits. This voltage is randomly varying or fluctuating, and when it is intermixed with a radar echo signal, it becomes impossible to tell with certainty whether a momentary increase of the receiver output is due to a signal or to a chance noise fluctuation. However, it is possible to define probabilities for these two possibilities and to discuss the detection process in terms of them in a quantitative manner. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.716x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 Much of the discussion relating to skywave radar carries over directly to HFSWR,  but there are a few areas where differences are significant: • The antennas must be designed and positioned to achieve high efficiency in  coupling to the surface wave mode. 
 3191; Switch unit, type 207; Waveform generator, type 26 or 27; Receiver, type 3516 or 3515 ( IF ampli ﬁer, detector and video ampli ﬁer); Indicator unit, type 163 or 162; Scanning unit, Type 51 ( for Halifax and Wellington XII aircraft of Coastal Command ); Power unit, type 224 or 280; Heading control unit, type 218; Voltage control panel type 5 or type 6 ( control of 80 V AC from engine generator ). Also included were the Lucero transmitter –receiver type TR. 3190 (Lucero Mk. 
    
 Therefore the amplitudes of the voltages in each element are the same  and, for convenience, will be taken to be unity. The sum of all the voltages from the individual  elements, when the phase difference between adjacent elements is t/J, can be written  Ea= sin wt+ sin (wt+ 1/1) + sin (wr + 2tjJ) +···+sin [wt+ (N -l)t/11 (8.1)  where w is the angular frequency of the signal. The sum can be written  E = sm wt + (N l) ·· ····· · · · . 
 This is sometimes called apodization. Weighting of the amplitude, as discussed later  in this section, is sometimes desired so as to reduce the time sidelobes accompanying the  compressed waveform.  The renective-array compressor (RAC) form of SAW device, shown schematically in  Fig. 
 Weather clutter, however, can be a  serious factor in limiting the performance of microwave radars even at frequencies as low as 1-  band. Good radar design must include methods for maintaining performance in the presence  of precipitation.  The most effective method for reducing the effects of precipitation is to operate at a low  frequency to'take advantage of the significant decrease in backscatter from precipitation with  decrease in frequency. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.616x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 The time-domain illustration shown previously in Figure 2.69 leads to the conclu - sion of Hall and Shrader32 that using an M out of N binary detector at the output of an  MTI filter will preclude false alarms from the clutter residues caused by limiting. Figure 2.71 shows, in addition to clutter residue, the returns from a target that was  superimposed on the distributed clutter prior to the clutter-plus-target sequence pass - ing through the IF limiting process. 
 Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft.  MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 the pilot on an azimuth-range display (shown in the lower right of Figure 5.25). The  terrain avoidance scan pattern shows all the terrain that is near or above the flight  altitude and one cut below at a set clearance altitude (500 ft. 
 {°Ó  2!$!2 (!.$"//+  4IME GATING ALLOWS THE BLANKING OF DIRECT TRANSMITTER LEAKAGE INTO THE RECEIVER 4HIS  PERMITS THE USE OF A SINGLE ANTENNA FOR TRANSMIT AND RECEIVE  WHICH OTHERWISE WOULD NOT BE FEASIBLE FOR #7 RADAR DUE TO EXCESSIVE TRANSMITRECEIVE ISOLATION REQUIREMENTS 0ULSED RADARS CAN ALSO USE RANGE GATING  A SPECIFIC FORM OF TIME GATING  WHICH DIVIDES THE INTERPULSE PERIOD INTO CELLS OR  RANGE GATES 4HE DURATION OF EACH CELL IS TYPICALLY  LESS THAN OR EQUAL TO THE INVERSE OF THE TRANSMIT PULSE BANDWIDTH 2ANGE GATING HELPS ELIMINATE EXCESS RECEIVER NOISE FROM COMPETING WITH TARGET RETURNS AND ALLOWS RANGE MEASUREMENT WITH PULSE DELAY RANGING IE  MEASURING THE TIME BETWEEN TRANSMISSION OF A PULSE AND RECEPTION OF THE TARGET ECHO  0ULSED TRANSMISSION DOPPLER RADARS HAVE HISTORICALLY BEEN CATEGORIZED AS  MOVING  TARGET INDICATION -4)  OR  PULSE DOPPLER -4) TYPICALLY ELIMINATES CLUTTER BY PASSING  THE RECEIVED RETURNS FROM MULTIPLE COHERENT PULSES THROUGH A FILTER WITH A STOPBAND PLACED IN SPECTRAL REGIONS OF HEAVY CLUTTER CONCENTRATIONS -OVING TARGETS WITH DOP 
 29. C. E. 
 Thevalueof(X2foraperfectly rectangular pulseisfiniteeventhoughitsvalueoffJ2is infinite.Thevalueofa2willbeinfinite,however, forawaveform withaperfectly rectangular frequency spectrum, corresponding toa(sinx)lxtimewaveform (x=nBt)ofinfiniteduration. Inpractice, anywaveform mustbelimitedintime,anda2willtherefore befinite.The frequency error(or(2)forawaveform withrectangular spectrum maybefoundinamanner similartothatemployed forcomputing fJ2forabandwidth-limited rectangrllar pulse.The frequency errorwillbelikethatofEq.(11.20)butwiththerolesofBandrreversed. Thermserrorinthemeasurement ofdoppler frequency withatrapezoidal pulseis (11.31) trapezoidal pulseb_ (2T2/3+2T1)1/2 '1-(2TfT2TIT~ T~2Tl)1/2(2E)1/22n+--+- +- 0- 3 3 153No Thisreduces totheexpression forarectangular pulse[Eq.(11.29)]asthetrapezoidal pulse becomes morerectangular, thatis,whenT1=r/2~T2• Forthetriangular pulse,wesetT1=0inEq.(11.31)andlet2T2=rB'Thermserroris {1O)1/2 . 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 7 .32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 Maneuver Model Q-submatrixSteady-state Gain Relation and  Tracking Index Tuning Method Characteristics Model no. 
 The airborne part of the Babs equipment, the interro- gator, sends out signals which are received by the trans- ponder at the end of the runway and retransmitted in a very sharply defined beam, the central axis of which  is switched rapidly first slightly to the left for a short interval, then slightly to the right for a longer  . tLoterval.  When the homecoming aircraft is ‘in’ the beam—that  is, exactly in line with the runway—signals from the  Babs beacon will appear level on the CRT screen, and if  pips are being injected into the intercom, then a con-  tinuous, steady howl will be heard. 
 The process of summing all the radar echo pulses for  the purpose of improving detection is called integration. MaRy techniques might be employed  for accomplishing integration, as discussed in Secs. 10.7. 
 4.31  4.8 Pulse Modulators  ....................................................  4.32  Line-Type Modulat ors  ........................................  4.33  Active-Switch Modul ators  ................................... 
 NETIC SERVICES 4HE LETTER 
 CORRELATED  THEY ARE SUBJECTED TO POSTDETECTION 34#  OR 2#3 THRESHOLDING  APPLIED INSIDE THE RANGE CORRELATION PROCESS 4ARGET RETURNS THAT RANGE CORRELATE INSIDE THE 34# RANGE  BUT FALL BELOW THE 34# THRESHOLD  ARE LIKELY SIDELOBE DISCRETES AND ARE BLANKED OR REMOVED FROM THE CORRELATION PROCESS AND KEPT FROM GHOSTING WITH OTHER TARGETS  4HE BASIC LOGIC IS SHOWN IN &IGURE   "ASICALLY  THE #&!2 OUTPUT DATA IS  CORRELATED RESOLVED  IN RANGE THREE TIMES %ACH CORRELATOR CALCULATES UNAMBIGUOUS RANGE USING  - OUT OF THE  . SETS OF DETECTION DATA EG  THREE DETECTIONS REQUIRED  OUT OF EIGHT 02&S  .O DOPPLER CORRELATION IS USED SINCE THE DOPPLER IS AMBIGUOUS  4HE RESULTS OF THE FIRST TWO CORRELATIONS ARE USED TO BLANK ALL OUTPUTS THAT ARE LIKELY TO BE SIDELOBE DISCRETES FROM THE FINAL RANGE CORRELATOR (ERE  THREE RANGE CORRELA 
 With these additional losses, the overall loss becomes 1.91 dB or 64% aperture  efficiency (typical for a single reflector system). Sidelobe requirements must also be considered. As shown in Figure 12.5, for the  same center-fed reflector system, the sidelobe level can be reduced by increasing the  feed pattern edge taper.−2−1.8−1.6−1.4−1.2−1−0.8−0.6−0.4−0.20 −20 −17.5 −15 −12.5 −10 −7.5 −5 Feed Pattern Edge Taper in dBLoss in dB TotalFeed Blockage Spillover Taper Efficiency FIGURE 12. 
  
 Bothrealandartificial dielectrics arenotalwaysperfectly uniform from sampletosampleorevenwithinthesamesample. Figure7.22The"tin-hat" geodesic analogoratwo­ dimensional Luneburg lens.. Evaluation of lenses as antennas. 
 Another application, in which ground clutter is serious, relates to the detection of low- level wind shear. While ground clutter cannot be eliminated, its effects can be mitigated through careful design. The most straightforward approach is to use antennas with low sidelobes, particularly in elevation. 
 IRE, vol. 36, pp. 1364-1370,  November, 1948. 
 ~--o o".§.et'3.0",­ fL L(J,)e> L0 (1)II> '0e2.0 <1JUa.......20 '"x1.0 ~ 234 Beamcrossover, dB5FigureS.1lSlopeoftheangular-error signalatcrossover foramonopulse andconical-scan trackingradar.08= 6halr·power beamwidth. Oq=squint angle.. TRACKING RADAR 165  squinted beams is not an easy task. 
 Spot cl~irl'l'is clr.opl>cd its  individual bundles which appear as additional targets on the radar in an effort to deceive the  operator as to their true nature.  A chaff corridor is produced by airscraft continuously releasing chaff to form a long  corridorlike cloud through which following aircraft can fly undetected. Tlie effect is to mask  tile aircraft, much like a smoke screen. 
 SCAN42  TRANSMITRECEIVE63  VELOCITY SEARCH , 
 Purduski114 © IEEE 1980 NOTE : q  = 20 to 70 °. Values of coefficients in this table are also considered those of the model.TABLE   16. 3 Regression Results for Ground-Based Measurements of Snow-Covered Ground*The figure is only for vertical polarization because results are so similar for  vertical and horizontal. 
 Oct. 23 -25, 1973, pp. 227-232. 
  
 As indicated in Fig. 10.16a, larger values of F1(^T < 0.08) increase the sidelobe level. For a given peak sidelobe level, Taylor weighting offers theoretical advantages in pulse width and SNR performance, as illustrated in Fig. 
 The value of o0 for sea clutter at low grazing angle and low winds has been rep~rted'~ to  "not increase with frequency much above X band," but also77 the "trend of increasing  reflectivity with decreasing wavelength also holds for sea clutter although the effect is not  nearly as pronounced as for land clutter." However, both references state that for higher sea  states (the maximum wind speed was 14 knots) the value of a0 at 94 GHz is less than that at X  hand. Another observation is that vertical polarization seems to produce lower values of a0 at  OTHER RADAR TOPICS563 appliesfortheregionaround183GHz.Therelativeminimum at94GHzwithanattenuation of0.3dB/kmisalikelyfrequency formillimeter radarapplications. Note,however, thatthe 94-GHz"window" hasevengreaterattenuation thanthe22-GHz water-vapor absorption line (0.16dB/km). 
 ARRAY LEVEL                        "       !  #"          
 NO. Ijolpl\. C'. 
 Spetner, LM.:Incoherent Scattering ofMicrowaves fromtheOcean,RadioSciellce, vol.10, pr.585-587, June,1975. Brown,B.P.:RadarHeightFinding, chap.22of"RadarHandbook," M.I.Skolnik(ed.),McGraw­ HillBookCompany. NewYork.1970. 
 Radiometric resolution determines how fine a  sensor can distinguish between objects with similar EM reflection properties. It is a  parameter of great importance, especially for those applications oriented to extended  target exploitation like polarimetry and classification. Thus, the radiometric resolu - tion should be optimized mainly for good extended target interpretation, accounting  for all kind of back-scatterers. 
 Rec ., San  Francisco, 1979, pp. 1–20. 34. 
 ERROR METHOD OF SCANNING THE JAMMING MODULATION UNTIL A NOTICEABLE REACTION OCCURS IN THE TRACKING RADAR BEAM 4HIS JAMMING TECHNIQUE IS CALLED JOG  DETECTION   ! SEQUENTIAL LOBING 
 BEAM AZIMUTH ANGLE IS GREATER THAN HALF OF THE AZI 
 Imbriale, W. A., P. G. 
 SIGNAL % FIELD &)'52%    &OUR 
 3.6 Detection performance of ASV Mk. III Trials of the performance of ASV Mk. IIIA in No. 
 To an observer looking In the  direction of propagation, a clockwise-rotating electric field is known as right-hand circular  polarization, and a counterclockwise rotation is known as left-hand circular polarization.  Right-hand and left-hand circular polarization are said to be orthogonal polarizations since an  antenna capable of accepting one will not accept the other. Similarly, horizontal and vertical  linear polarizations are orthogonal. 
 INTERVAL RATIO . Ó°{{  2!$!2 (!.$"//+  THERE WILL BE A VOLTAGE RESIDUE FROM THE CANCELERS THAT IS PROPORTIONAL TO THE SLOPE    A AND INVERSELY PROPORTIONAL TO  F   
 IfN*isrequired tobe,forexample, 10,therate of rotation ofthe antenna inthe previous example must berestricted to 0.14 rpsorabout 9rpm.1 The numbers arrived atinthis example are typical oflong-range ground-based microwave radar. Any considerable improvement inall three characteristics—range, scanning speed, and angular resolution— will beblocked byirreconcilable requirements aslong asasingle radar set isrelied upon for the entire coverage. But the restriction falls even more severely onradar systems designed tosearch rapidly iritwo angular coordinates rather than inone. 
 This causes an azimuthal variation of s 0, as shown  in Figure 16.38.148 The modulation shown is the ratio of s 0 looking parallel to the rows  (more vegetation) to that looking normal. This phenomenon is much more pronounced  at the lower frequencies. Some general properties of vegetation scatter are visible in Figure 16.39.149 At low  frequencies, the decay with q  is rapid out to about 20° and then more gradual; most  of the steep part results from surface echo. 
 This switching is necessary because  the high -power pulses  of the transmitter would destroy the receiver if energy were allowed to enter the receiver.    The antenna transfers the transmitter energy to signals in space with the required  distribution and efficiency. This process is applied in an  identical way on reception. 
 The object usually isto increase the angular region covered atone time. Anexample ofsuch a radiation pattern isthe simple “fan beam” sketched inFig. 2.1. 
 It is a frequency-scan radar used on many U.S. Navy ships for the  measurement of the elevation and azimuth of aircraft targets. It is sometimes called a 30 radar,  *ith range being the third coordinate, in addition to the two angles. 
 William Blair)  USA, NRL XAF Ship Radar 200 MHz, 6 kW, 50 Miles.   Radar technology underwent rapid development during the years of the Second World War.  An exam ple for this is the founding of the Radiation Laboratory at MIT (Massachusetts Institute of  Technology). 
 This also improves  the reliability. The tritium-activated TR is usually followed by a diode limiter. The combina­ tion of the two is called a passive TR-limiter and is widely used as a receiver protector. 
 66, no. 12, pp. 1592–1618, December 1978. 
 In this situation, it might be proper to resort to auto - matically applied ECCM techniques; this is the tendency today. However, a possible  concern is that this could, sometimes, hurt the ECCM capability of the radar since a  well-trained operator can often figure out what is happening; but the automatic proces - sor can only make decisions based on preprogrammed logics installed in its computer  and might not recognize when something unusual (as in jamming) occurs. This is a  possible adverse effect of the absence of a decision-making operator. 
 4.8). Phase-Modulation Sensitivity. This indicates how hard the transmitter de- signer must work to ensure that system phase-stability requirements will be met (Sec. 
 The typical average radi - ated power, integrated over the band of interest, may be in the order of a milliwatt, but  the power per Hz may be as low as picowatts. GPR is usually operated so that the target, which is within a lossy dielectric, is  only a few wavelengths from the aperture of antenna. The total path losses within a  few wavelengths may reach 100 dB or more depending on the material. 
 The Cassegrain principle is widely used in telescope design to obtain high magnification wit\\ a  physically short telescope and allow a convenient rear location for the observer. Its application  to microwave reflector antennas permits a reduction in the axial dimension of the antenna, just  as in optics. But more importantly it eliminates the need for long transmission lines and allows  greater flexibility in what can be placed at the focus of the antenna. 
 Thus the correct value is uncertain. The  ambiguity diagram permits a visual indication of the ambiguities possible with a particular  waveform. The ambiguity problem is characteristic of a single target, as is the detection and  accuracy requirements of a waveform, whereas resolution is concerned with multiple targets. 
   LOBE CANCELLATION SYSTEM OR BY USING DIGITAL BEAMFORMING )N A  $"& SYSTEM  ADAPTIVE  BEAMFORMING IS ACCOMPLISHED EITHER WITH THE USE OF SUBARRAY RECEIVERS OR WITH AUX 
 These are reactil'e feed systems. They are basically used with a linear array and would have to  be stacked to feed a planar array.  Subarra)·s. 
 Improved global range alignment for ISAR. IEEE T rans. Aerosp. 
 CONTINUUM BACKGROUND NOISE AT THE LOWER FREQUENCIES  IS LIGHTNING DISCHARGES IONOSPHERICALLY PROPAGATED FROM ALL OVER THE WORLD  SFERICS   !T THE HIGH 
 Survivability and Vulnerability. SBR system survivability and vulnerability must be demonstrated and tested. The natural space radiation environment will cause a significant total dose on a T/R module depending upon its shielding. 
 thatthisisnotfundamental andthatequipment shortcomings eventually canbeovercome withsufficient effort.Thereexistsadequate technology toeither sideofthemillimeter wavespectrum: atthelongerwavelengths (microwaves) andatthe shorter wavelengths (IRandvisual).Also,therearecomponent developments atmillimeter wavelengths whichindicate thattechnology isnotbasically limited.Forexample, highpower hasbeendemonstrated withthegyrotron, orelectron cyclotron maser,comparable tothat achieved withmicrowave devices. Kilowatts ofCWpowercanbeobtained inthevicinityof I-nUllwavelength andseveraltensofkilowatts at3-mmwavelength.72Overamegawatt of pulsepowerisclaimed atJ-mmwavelength. Millimeter-wave gyrotrons requireextremely highvoltages (theelectrons travelatrelativistic velocities) andsuperconducting magnets. 
 However, only hth the total range interval can be processed. This disadvantage may be  I~othersome in a surveillance radar, but it might be well suited to a tracking radar or to a  high-range-resolution radar used for target classification. The technique uses elements similar  to those of the linear-FM pulse-compression radar. 
 It is noted that the magnitude of the height error is directly related to the surface refractivity and that above approximately 40° elevation angle the height error is independent of the surface refractivity. The height error is given in Table 20.2 as a function of slant range. TABLE 20.1 Estimates of Height Error at an Altitude of 100,000 Ft Based on the CRPL Reference Refractivity Atmosphere—1958 TABLE 20.2 Estimate of Height Error at Slant Ranges of 100, 200, and 300 nmi Based on the CRPL Reference Refractivity Atmosphere—1958 * Approximate slant range. 
 CHANNEL  RECEIVING SYSTEM SHOULD DELIVER A SINGLE OUTPUT  ASSIGNED TO THE CORRECT DIRECTION  FOR A PLANE WAVE INCIDENT ON THE ANTENNA ARRAY )NEVITABLE VARIATIONS IN GAIN AND PHASE ARIS 
 MENTS EVEN UNDER THE BEST CIRCUMSTANCES )NERTIAL SENSORS ARE EXTREMELY GOOD OVER SHORT SPAN TIMES  BUT VELOCITY DRIFT IS A MAJOR LONG 
 Recycling takes place when therotor passes through thesector inwhich there isnostator. The shaft isgeared insuch away that the condenser rotates 360° during onescanning cycle. Since C’isnever zero, theoutput voltage hasaconstant term which must beremoved insome way. 
 151.Gabriel, W.F.(ed.):SpecialIssueonAdaptive Antennas, IEEETrans.,vol.AP-24,September, 1976. 152.Sharp,E.D.:ATriangular Arrangement ofPlanar-Array Elements thatReduces theNumber Needed, IRETrans.,vol.AP-9,pp.126-129, March,1961. 153.Cheng,D.H.S.:Characteristics ofTriangular LatticeArrays,Proc.IEEE,vol.56,pp.1811-1817, November, 1968. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.60  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 spherical assumption from the 700-km downrange position will give paths that are  slightly long for one-hop ranges. 
 Because the chart is intended only to display the  wide range in RCS that may be encountered in practice, the locations of targets on the  chart are approximate at best. Within given target classes, the RCS may be expected  to vary by as much as 20 or 30 dB, depending on frequency, aspect angle, and specific  target characteristics. Readers seeking more explicit detail than this should consult  referenced material at the end of this chapter.FIGURE 14.12  Measured RCS of a one-third scale model C-29 military aircraft20 ch14.indd   14 12/17/07   2:46:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The basic receiver described above folds the spectrum around feedthrough, which occurs at dc. Although in the moving missile this does not produce an ambiguity, in the tracking illuminator the inbound targets must be distinguished from the outbound. This unfolding of the spectrum was initially achieved by use of a quadrature receiver (Chap. 
 Synthesizer.  The synthesizer generates the transmit carrier frequency and the  first local oscillator (LO1) frequency. Frequency agility is provided to the transmit  and LO1 signals. 
 F. Shaeffer, and M. T. 
 For accurate matching, images need to have a uniform scale. The bandwidth of ky represents the range bandwidth after interpolation. In order to have the same range resolution of multiple-angle images in the time domain, the bandwidth of kyis required to be the same. 
 TION AND SUBSEQUENT DIGITAL SIGNAL PROCESSING  AT MORE READILY ACHIEVABLE SAMPLE RATES "Y APPLYING A SUITABLY MATCHED CHIRP WAVEFORM TO THE RECEIVER FIRST ,/  COINCIDENT WITH THE EXPECTED TIME OF ARRIVAL OF THE RADAR RETURN  THE RESULTANT )& WAVEFORM HAS A SIGNIFICANTLY REDUCED BANDWIDTH FOR TARGETS OVER A LIMITED RANGE 
 CAL MISSION PROFILE FOR AIR 
 02& WAVEFORM WITH RANGE AND DOP 
 F WILL BE OCCUPIED BY SPECTRAL COMPONENTS ALSO  SO THE TWO 
  
 3.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 for the given platform motion, these three apertures appear as if they are stationary  with respect to each other. Clutter cancellation across these three pulses is no longer  limited by platform motion effects—the primary goal of platform motion compensation  techniques. Of course, this simplest condition is only illustrative, as generally the antenna ele - ments do not behave exactly the same, and the platform motion compensation must deal  with motion not only in the plane of the aperture but also orthogonal to the aperture. 
  
 Datasets using Resnet-50 model. Dataset Accuracy (%) D1 94.67 D2 95.43 D3 98.52 As shown in Table 6, these results show that the deep networks with transfer learning have better performance than the traditional CNN models when dealing with the three datasets. We can achieve at least 3% higher accuracies for classiﬁcation when compared with dataset using traditional CNN model. 
 TENTH OF FULL SCALE  FOR EXAMPLE  IT SHOULD BE MEASURED AT ONE 
 This thought has the advantage of easily locating moving ships in SAR images and the data size of sub-image is also smaller than the entire raw data. To deal with these problems, a refocusing method for moving ships based on fast minimum entropy phase compensation is proposed in this paper. The processing data are sub-images containing moving ships rather than the raw echo data, and the ISAR technique is based on fast minimum entropy phase compensation. 
 13. May, J. E., Jr.: Ultrasonic Traveling-Wave Devices for Communications, IEEE Spec- trum, vol. 
 At 0 7 0 (bc;t~l~ I)rooclside to lllc array) a syrl~~ttctrical pcticil I)c:trtt of  lialf-power width 11" is assumed. The shape of the beam at the other angular positions is the  prc!jection of tlic circular I,earr~ shape ott the surface of the unit sphere. It call be seer1 that as  the hcarn is scarlrled in tlie O direction, it broadens in that direction, but is constant in the 4  direction. 
 The discussion of HF RCS and sea clutter in  Sections 20.7 and 20.8 applies equally to HFSWR; indeed, the absence of the cor - rupting effects of the ionosphere provides even greater scope for exploiting the scat - tered signals. Furthermore, although the increased rate of decay of the surface wave at  higher frequencies imposes a limit on the range of frequencies that might be used to  detect a target at a given range, the situation is by no means as restrictive as for sky - wave propagation. This raises the possibility of exploiting multiple frequencies more  effectively, so as to extract additional target and sea-state information and unmask  targets hidden in clutter. 
 The MTI cancellation may also be done at IF rather than in the video after the phase  detector.' Although there may be some advantages in IF cancellation (such as no blind  phases), it is more complicated than video cancellation. It is difficult for IF cancelers to  compete with the flexibility and convenience of digital processing containing I and Q channels.  FM delay-line cancelers have also been considered for MTI application. 
 For this situation the variability from place to place is small, particularly in the midrange of angles. Figure 12.27 shows the mean and upper and lower decile val- ues measured by the Skylab RADSCAT over North America. The larger varia- tion near vertical apparently results from the effect of nearly specular reflection from water bodies. 
 Not only main-lobe but also sidelobe clutter must be con- sidered. The spectrum of Fig. 19.3« shows the case of a ground-to-air missile. 
 16, pp. 29-33, March, 1973.  40. 
 Conformal arrays.130 135 One of the desires of the radar systems engineer is to be able to  place array elements anywhere on an arbitrary surface and achieve a directive beam, with good  side lobes and efficiency, which can be conveniently scanned electronically. An array of radiat­ ing elements arranged along the nose of an aircraft, on the wing, or the fuselage would thus be  an attractive option for the systems designer. Such an array, which conforms to the geometry  of a nonplanar surface, is called a conformal array. 
 Lewis, “Range-time-sidelobe reduction technique for FM-derived polyphase PC codes,”  IEEE Transactions on Aerospace and Electronics Systems , vol. 29, no.3, pp. 834–863, July 1993. 
 16-2A to 16-2F. Sept. 26-28. 
 MUTH SECTOR CONTAINING THE JAMMER OR REDUCING THE SCAN SECTOR COVERED ARE MEANS TO PREVENT THE RADAR FROM LOOKING AT THE JAMMER #ERTAIN DECEPTION JAMMERS DEPEND ON ANTICIPATION OF THE BEAM SCAN OR ON KNOWLEDGE OR MEASUREMENT OF THE ANTENNA SCAN RATE 2ANDOM ELECTRONIC SCANNING EFFECTIVELY PREVENTS THESE DECEPTION JAMMERS FROM SYNCHRONIZING TO THE ANTENNA SCAN RATE  THUS DEFEATING THIS TYPE OF JAMMER ! HIGH 
 If a blue filter were used instead, the persisterlt afterglow of  the second layer wou1d be removed, leaving only the short-duration flash. Thus a single  cascade screen can give either a short or a long persistence display, depending upon the filter  employed.  In Table 9.1 the color emitted by the screen during both fluorescence (short duration) and  phosphorescence (long duration) is given. 
   .   !)2"/2.% -4)  Î°Ç THE SYSTEM REFERENCE OSCILLATOR FREQUENCY VIA THE AUTOMATIC FREQUENCY CONTROL !&#   LOOP SHOWN IN &IGURE  4HIS PROVIDES A STABLE REFERENCE IN THE ABSENCE OF CLUTTER !N INPUT FROM THE AIRCRAFT INERTIAL NAVIGATION SYSTEM AND THE ANTENNA SERVO PROVIDE A PREDICTED DOPPLER OFFSET 4HESE INPUTS ALLOW THE 4!##!2 SYSTEM TO PROVIDE A NARROW 
 Inthe circuit ofFig. 13”26, the transformer-coupled grid circuits form closed loops which draw no current whatever from thereference point. This circuit iswidely used asademodulator incases where thephase ofthecarrier with respect tothereference signal isofimportance. 
 OF 
 79. Sclloolcr. (' C'.: 0l~tiri1:il 7-11 1:iltcrs for Systcrns with Modeling Iriaccuracics, IEEE Tt~rtu.. 
 The first  heavy bomber installed with H2S crashed on an experi-  mental flight, and all the crew and five of the pioneer  experimenters were killed.  What the H2S picture may show is not the scene  immediately below the aircraft, but at some slant range  ahead. Thus if the slant is known the height of the  aircraft itself can be calculated, which is an additional  navigational aid. 
 ", Ê 
 Headrick, R. W. Bogle, and D. 
  
 The beam scans a60°azimuth sector in~see, or1to-and-fro cycle inl+sec. The range ofthe Eagle system forground-mapping isabout 50miles. The antenna isaslender linear array 16ftlong, which fits into a streamlined housing (vane) hung laterally beneath theaircraft that uses it(Fig. 
 &- WAVEFORMS .   05,3% #/-02%33)/. 2!$!2   n°£Î WHERE THE COEFFICIENTS ARE  +    
 98–100,  April 1998. 47. A. 
 The modulation and demodulation to obtain range arc the same as used in CW radar, but the transmission remains pulsed. Assume that the dwell time is divided into two periods. In the first period, no FM is applied, and the doppler shift of the target is measured. 
 5, pp. 292–307,  April 1926.  4. 
 Abrief account oftheir properties and uses, though not oftheir design, will be found inChap. 8. Toward theend ofthewar, two major’ developments occurred which promised toextend greatly theapplicability ofpulse radar under unfavor- able conditions. 
 312 INTRODUCTION TO RADAR SYSTEMS  Crossed-line  directional coupler  ~  . c \  \ \,  !... !... 
 40.Jensen. A.S.:TheRadechon. ABarrierGridStorage Tube,RCARev.,vol.16.pp.197-213, June, 1955. 
 Johnson, “The Seasat—a satellite scatterometer,” IEEE  Trans. , vol. OE-2, pp. 
 Aircr~fi Navigation. The weather-avoidance radar used on aircraft to outline regions or preci­ pitation lo the pilot is a classical form of radar. Radar is also used for terrain avoidance  and terrain following. 
 Specific electronic techniques take place  in the main radar subsystems, namely, the antenna, transmitter, receiver, and sig - nal processor. Table 24.1 shows a categorization of some ECCM techniques along  with the ECM techniques that are used to counter.5,28 Suitable blending of these  ECCM techniques can be implemented in the various types of radars, as discussed  in Section 24.11. The ensuing description is limited to the major ECCM techniques; the reader should  be aware that an alphabetically listed collection of 150 ECCM techniques and an ency - clopedia of ECCM tactics and techniques can be found in the literature.8,29 Many other  references describe the ECCM problem, among which Slocumb and West,5 Maksimov  et al.,21 Gros et al.,30 and Johnson and Stoner31 are worth noting. 
 FED  OFFSET  SINGLE  DUAL  ETC  AS LONG AS THE REFLECTOR SIZE IS APPROXIMATELY  K OR  LARGER -ORE DETAILED DESCRIPTIONS OF '4$54$ CAN BE FOUND IN VARIOUS REFERENCES   &ULL 
 271-288, April, 1953.  4. Collins, G. 
 Therefore (4.32) Thisappliestothevoltagespectrum. Sincethestandard deviation ofthej.)owerspectrum is lessthanthatofthevoltagespectrum byfl,thepowerspectrum duetoantenna scanning can bedescribed byastandard deviation 50 rn "0 a40- u 2 C '"E30- '"> 0a E 20-1.178 1 a$=J2nto=3.77to ~.numberofhitswithin(4.33) Figure4.31Limitation toimprovement factorduetoascanning antenna. Antenna patternassumed tobe ofgaussian shape.. 
 The defocused area and focused area of imaging result on the reference plane. The imaging results by the two imaging methods in Cartesian coordinate system are shown in Figure 22. It can be seen that the ArcSAR imaging result of the scenes on the reference plane showed severe defocusing, and the ArcSAR image obtained by the proposed imaging method was not defocused. 
 The value of cr2 will be infinite, however, for a waveform with a perfectly rectangular  frequency spectrum, corresponding to a (sin x)/x time waveform (x = nBt) of infinite duration.  In practice, any waveform must be limited in time, and a2 will therefore be finite. The  frequency error (or a2) for a waveform with rectangular spectrum may be found in a manner  similar to that employed for computing P2 for a bandwidth-limited rectangdlar pulse. 
 (d) Flexible waveguide, corrugated wall. Bends inwaveguide such asthose inFig. 11.1 lacause inappreciable mismatch ifthe inside radius isgreater than twice the free-space wave- length. 
 (2.9)20INTRODUCTION TORADAR SYSTEMS 2.4PROBABILITY-DENSITY FUNCTIONS Thebasicconcepts ofprobability theoryneededinsolvingnoiseproblems maybefoundin anyofseveralreferences.4-8 Inthissection weshallbrieflyreviewprobability andthe probability-density function andcitesomeexamples. Noiseisarandom phenomenon. Predictions concerning theaverage performance of random phenomena arepossible byobserving andclassifying occurrences, butonecannot predictexactlywhatwilloccurforanyparticular event.Phenomena ofarandomnaturecanbe described withtheaidofprobability theory. 
 In a rank- selection process, the “r- th” largest amplitude is chosen as a repre- sentative of the clutter. The TV is calculated using a multiplicative α or add itive factor β as  described for the CAGO- CFAR above. Target detection is accomplished by comparing the  SUT with the TV. 
  4HE LARGEST ECHO SOURCE IN THE 32 
 The false-alarm probability depends upon the miss probability in the case of the Ideal  Observer. This is unlike the Neyman-Pearson Observer in which Pf, was fixed. The function of  the Ideal Observer is to minimize the total probability of error. 
 An intensity-modulated rectangular display with azimuth angle indicated by the horizontal  coordinate and elevation angle by the vertical coordinate.  D-scope. A C-scope in which the blips extend vertically to give a rough estimate or distance. 
 DOMAIN MULTIPLEXING  REQUIRES ADDITIONAL LOGIC TO CONTROL THE SYSTEM AND PROVIDE  THE CORRECT OPERANDS TO THE MULTIPLIER AT THE RIGHT TIME 3INCE AN &0'! CAN INCORPORATE HUNDREDS OF MULTIPLIERS  ONE CAN APPRECIATE THE POWER OF THIS TECHNIQUE /N THE NEGATIVE SIDE  UTILIZING AN &0'! TO ITS BEST ADVANTAGE TYPICALLY REQUIRES THE  DESIGNER TO HAVE A THOROUGH UNDERSTANDING OF THE RESOURCES AVAILABLE IN THE DEVICE 4HIS TYPICALLY MAKES EFFICIENT &0'! 
 Inthe opposite limiting case (A<<a)the cross section approaches thegeometrical cross section ~az. Between these limits are theresonance maxima. 0.05 0.1 0.2 0.4 0.6 1.0 2 4 a/~ ~.3.1.—Bark scattering from ametallic sphere. 
 174. D. P. 
 49. Peebles, P. Z., Jr.: Multipath Angle Error Reduction Using Multiple-Target Methods, IEEE Trans.,  vol. 
 A sample rate of 360o/sec and a 2o half- power bandwidth result in a  dwell time of 1/180 sec.  That means tha t the integration filter has a bandwidth of 180 Hz.   The integration effect is obtained by the energy storage in the filter. 
 It could also interrogate centimetric beacons. ASV Mk. XIIIA was intended for all-round search, using scanner type 75 (re ﬂector size 18 ″×12″) which was unstabilised. 
 These echoes will beat with thereference signal. The presence ofcycles within theechoes, when viewed onanexpanded A-scope, will show when thelocal oscillator isout oftune. Since the coherent oscillator isunlikely todrift, the tuning ofthelocal oscillator togive maximum receiver response needs to bechecked only rarely. 
 12.Graham, L.c.:Stereoscopic Synthetic ArrayApplication inEarthResource Monitoring. /EEE NAECON '75Record, pp.125-132, 1975. 13.Bair,G.L.,andG.E.Carlson: Comparative Evaluation ofStereoRadarTechniques UsingCom­ puterGenerated Simulated Imaginary, IEEENAECON '74Record, pp.220-227,1974.. 
 M.: History of the Directional Antenna in the Standard Broadcast Band for the  Purpose of Protecting Service Area of Distant Stations, IRE Trans., vol. PGBTS-7, pp. 51 55. 
 An altimeter’s revisit period is ten days or more, in contrast to tides with approxi - mately 1 or 2 cycles per day driven primarily by lunar and solar gravity. As a result,  all tidal signals sensed by an altimeter are undersampled. Altimetric data retain the  resulting aliases, which over the course of a year or so can be identified, quantified,  and calibrated out. 
 POWER 3 
 The outer metal case ofthis component islined with sound-proofing material. The parts within are mounted onametal base-plate which isinturn supported byfour circular shear rubber shock mounts ofconventional design, notvisible inthephotograph.. 660 MOVING-TARGET INDICATION [SEC. 
 D" 4AYLOR WEIGHTING REDUCES THE PEAK TIME SIDELOBE LEVEL FROM  n D" TO n D" AND INTRODUCES A  D" LOSS IN 3.2 4HE  
 Maintenance of  the internal pressure in high winds can sometimes be difficult. Another problem is that costly  maintenance is requirccJ at frequent intervals.  The limitations of air-supported radomes are overcome by the use of rigid seir-supporting  radomes. 
 59. Mallett, J. D., and L. 
 Ulaby developed a different, more complex model from the Kansas vegetation data.85 This model fits curves rather than straight lines to the measured data. For most purposes the straight-line model is adequate, and it is much easier to use. A straight-line model for snow-covered grassland similar to that for vegetation depends on a more limited data set.86'87 The data was for only one season in Colorado when the snow was only about 50 cm deep. 
 The various  lengths of line arc inserted and removed by high-speed electronic switching. Semiconductor  diodes and ferrites arc the devices commonly employed in digital phase shifters.  There are at least two methods for switching lengths of transmission lines. 
 2. Basic Multiple Aperture Mapdrift Method The core strategy of the MAM method divides the data along the azimuth into multiple blocks and generates multiple sub-view images. By searching the offsets between two different sub-view images, it is possible to estimate the higher order Doppler parameters. 
 The various methods for interfering electronically with radar are  called t~lectrotlic. cotr~rtrrri~c~cistrt~es, or ECM. Actirtcj ECM is sometimes referred to as ,jrir~rrtti~~g. 
 9, no. 4, pp. 89-90, Feb. 
 Themeasured MTIimprovement factoroftheMTDonanASRradarwasabout45dB,whichrepresented a20dBincreaseover theASR'sconventional three-pulse MTIprocessor withalimitingIFamplifier. Inaddition, theMTDachieves anarrower notchatzerovelocityandattheblindspeeds. Theprocessor ispreceded byalargedynamic rangereceivertoavoidthereduction in improvement factorcausedbylimiting(Sec.4.8).TheoutputoftheIFamplifier isfedtoIand Qphasedetectors. 
 $OPPLER "LIND -AP  &OR EXAMPLE  A TYPICAL -02& SET  FOR 8 BAND WITH RANGE 
 BASED OCEANOGRAPHIC ALTIMETER  THE DECEPTIVELY SIMPLE PROPORTIONALITY OF RANGE TO DELAY 
 ON  CONDITION AND  FOR A TAIL CHASE 4HE ASPECT ANGLE CORRESPONDING TO THE BOUNDARY BETWEEN THE SIDELOBE CLUTTER REGION AND THE SIDELOBE CLEAR REGION IS A FUNCTION OF THE RELATIVE RADAR 
 The production scanner weighs 165lb; thehousing vane weighs 247lb,including thegear box and motor. Thus theentire assembly, exclusive ofthetwo mounting struts, weighs 412 lb.mentioned above and sketched ‘-1 4-~[~~:.~0.100”0.660”Tomagnetron O.uo - 1:“ ‘k+To~ples 4(a) AL }Choke I1.200”Tom~etron I 1;“ - Todipdes1 F1c+. 9.23.—Jog transition from therigid totheexpandable guide. 
 BASED FACILITIES %ACH IMAGING PASS GENERATED  RADAR IMAGES THAT WERE COMBINED INTO A SURVEY STRIP OF  KM WIDE BY  KM LONG 4HESE WERE SUBSEQUENTLY COMBINED INTO MOSAICS 4HE SPACECRAFT INCLUDED A  
 Conopulse provides the monopulse advantage of avoiding errors caused by amplitude scintillation, and it requires only two receivers. However, it has the disadvantage over conventional monopulse radar of lower angle data rate and the mechanical complexity of providing and coupling to a pair of rotating antenna feedhorns. 18.4 SERVOSYSTEMS FOR TRACKING RADAR The servosystem of a tracking radar is the portion of the radar that receives as its input the tracking-error voltage and performs the task of moving the antenna beam in a direction that will reduce to zero the alignment error between the an- tenna axis and the target. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.58  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 The mismatch loss has now been reduced to 0.71 dB. 
 21. M. V . 
 AMPLITUDE h"RAGG SCATTERING WAVELETSv WHOSE INTEGRATED RMS WAVEHEIGHT SATISFIES THE CONDITIONS OF %Q  AND ANOTHER THAT CONTAINS ONLY THE LONGER WAVES THAT TILT AND STRETCH AND OTHERWISE MODULATE THE "RAGG WAVES  AFFECTING THE "RAGG SCATTERERS THROUGH A  MODULATION TRANSFER FUNCTION    AS WELL AS PROVIDING A SPECULAR COMPONENT  RESEMBLING %Q  /THER ASSUMPTIONS INCLUDE THAT   THE CORRELATION LENGTHS OF THE SHORT "RAGG WAVES BE LONG ENOUGH THAT A RESONANT INTERACTION IS POSSIBLE  BUT SHORT ENOUGH THAT ADJACENT AREAS ON THE SURFACE CONTRIBUTE TO THE TOTAL SIGNAL IN RANDOM PHASE NOTE HOW h"RAGG WAVESv ARE VIEWED HERE AS PHYSICAL OBJECTS  AND   THE LONG WAVES THAT TILT AND MODULATE THE SHORT WAVES HAVE RADII OF CURVATURE SUFFICIENTLY LARGE THAT THE CURVATURE OVER THE CORRELATION LENGTH OF THE h"RAGG PATCHESv IS SMALL IN SOME SENSE )N ITS SIMPLEST AND MOST COMMONLY USED hTILTv FORM  IT INTERPRETS  R    X   IN %Q   AS  THE CROSS SECTION OF A PATCH WITH  LOCAL GRAZING ANGLE  X    R     @   WHERE  @  IS THE LOCAL  WAVE SLOPE AND  X  IS THE MEAN GRAZING ANGLE &OR THE SIMPLE ONE 
 Although this is a rather simple example of a "complex" target, it is complicated  enough to indicate the type of behavior to be expected with practical radar targets.  The radar cross sections of actual targets are ~ar more complicated in structure than the  simple two-scatterer target. Practical targets are composed of many individual scatterers, each  with different scattering properties. 
 Consider first the case wlicre P # 18U0, for which the following theorem applies: " in tlic  limit of vanishing wavelengtl~ the bistatic cross section for the transmitter direction k^ and  rcceiver direclion ;I, is cqilal to the monostatic cross section for the transmitter-receiver  direction k + ;I, with k^ i: il,, for bodies which are sufficiently smooth." In the preceding. is  the unit vector directed from the transmitter to the target and ;lo is the unit vector directed  from the receiver to tlic target. The target is assumed to be located at the origin of the  coordinate systern. 
 When the radar transmitter and receiver are colocated, the doppler frequency fd obeys the relationship , 2vr/r fd = ~ where fT = transmitted frequency c = velocity of propagation, 3 x 108 m/s vr = relative (or radial) velocity of target with respect to radar Thus when the relative velocity is 300 m/s, the doppier frequency at X band is about 20 kHz. Alternatively, 1 ft/s corresponds to 20 Hz at this frequency. Scal- ing is a convenient way to handle other microwave frequencies or velocities. 
 and Remote Sensing , vol. 35, pp. 5–17, 1997. 
 Proper normalization requires that the angular dispersion bekept proportional tothe range tothecenter ofthedisplay. The vertical analogue ofthetype Bdisplay, known as“type E,” will bedescribed inthenext section. 6.6. 
 To use Fig. 17.21, a value of g(PFA,N) is first found from Fig. 17.20; this can then be used to convert gR/R0 values to RIR0 or signal-to-noise-ratio values. 
 GATION ENVIRONMENT !2%03 COMPUTES AND DISPLAYS A NUMBER OF %- SYSTEM PERFORMANCE ASSESSMENT  TACTICAL DECISION AIDS 4HESE ARE RADAR PROBABILITY OF DETECTION  %3- VULNERABILITY  ,& TO %(& COMMUNICATIONS  SIMULTANEOUS RADAR DETECTION AND %3- VULNERABILITY  AND SURFACE 
 The panels should be non-erosive,  water repellent, and designed to reject much of the incident solar radiation. In some radomcs,  the exterior surface is coated with a white radar-transparent paint, such as Hypalon, to reduce  the interior temperature rise caused by solar radiation.  A metal space-frame radorne might consist of individual triangular pands madc up of a  frame of aluminum extrusions encapsulating a low-loss dielectric reinforced plastics laminate  membrane. 
 This approach is generally successful  in reducing the amount of required weighting and ther efore the resulting mismatch loss, but  the residual Fresnel ripple in the sp ectrum often limits the resulting pulse compre ssion side  lobes [7]. Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  126          Figure 12.18  Matched filter compressed output (gray) and matched filter with added  Gaussian weighting.       Figure 12.19  Compressed output using phase -only matched filter with Gaussian wei ghting  filter. 
 MONOSTATIC REGION OCCURS AT  A   n  BISTATIC AT  n   A   n   AND FORWARD SCATTER AT  A   n 4HE OTHER TWO GEOMETRIES SHOW A SIMILAR BUT BROADER  FORWARD 
 6.34  6.7 Design Considerations  ...........................................  6.34  Feed Blockage  ..................................................  6.34  Feed Spillover and Diffr action  ............................ 
 MENTS DO NOT APPLY FOR THE SOLID 
 The early developments of pulse radar were primarily concerned with military applica-  tions. Although it was not recognized as being a radar at the time, the frequency-modulated  toINTRODUCTION TORADAR SYSTEMS nevercarriedout,however. ThelimitedabilityofCWwave-interference radartobeanything morethanatripwireundoubtedly tempered whatlittleofficialenthusiasm existedforradar. 
 RATE ESTIMATORS 3ELIGA AND "RINGI  AND 3ACHIDANANDA AND :RNIC SHOW HOW THE  CO 
 Thewide-angle scanning capability ofalenswouldbeofinterestinradarasacompetitor foraphasedarrayiftherewereavailable apractical meansforelectronically switching the transmitter andreceiveramongfixedfeedssoastoachievearapidlyscanning beam. 7.6PATIERN SYNTHESIS Theproblem ofpatternsynthesis inantennadesignistofindtheproperdistribution ofcurrent acrossafinite-width aperture soastoproduce aradiation patternwhichapproximates the desiredpatternundersomecondition ofoptimization. Pattern-synthesis methods maybe dividedintotwoclasses,depending uponwhether theaperture iscontinuous oranarray.The currentdistributions derivedforcontinuous apertures maysometimes beusedtoapproximate thearray-aperture distributions, andviceversa,whenthenumberofelements ofthearray­ antenna islarge.Thediscussion inthissectionapplies,forthemostpart,tolinearone­ dimensional apertures ortorectangular apertures wherethedistribution isseparable, thatis, whereA(x,z)=A(x)A(z). 
 Butler, “The microwave tube reliability problem,” Microwave J ., vol. 16, pp. 41–42,   March 1973. 
 List of the interferometric pairs and their parameters with image number 7 as the master (orbit no. 119, descending). Image No. 
  AND AZIMUTH ANGLEnDEPENDENT ATMOSPHERIC REFRACTIVITY  DATA DERIVED FROM THE UPPER 
 120–130. ch02.indd   101 12/21/07   10:19:31 AMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Hoisington, D. B., and C. E. 
 Focusing action is a result of the difference in the velocity of  propagation inside the dielectric as compared with the velocity of propagation in air. The  index of refraction 17 of a dielectric is defined as the speed of light in free space to the speed of  light in the dielectric medium. It is equal to the square root of the dielectric constant. 
 Despite the power of this technique, the spatial  resolution in the derived three-dimensional motion fields is generally not better than FIGURE   19. 10 Radar reflectivity contours and  air flow vectors superposed on photograph of a rap - idly growing Alabama thunderstorm cell. The data  depicts a 30 m/s updraft originating in an extremely  strong 60 dBZ rain or hail core. 
 8. D. B. 
 16.8. Receiver Characteristics. -Ideally, an MT1 system would remove allclutter signals from thescope, maintaining thegreatest possi- blesensitivity formoving targets both inthe clear and inthe clutter. 
 TION LOSSES ARE MINIMIZED  THOUGH THIS BENEFIT MUST BE BALANCED AGAINST ANTENNA SIZE  THE HIGHER NOISE ENVIRONMENT  AND OFTEN  REDUCED TARGET 2#3 AND II  THE RAPIDLY ACCELERATING FALL 
 The facet model for radar return is extremely useful for qualitative discussions,  and so modification to make it fit better with observation is appropriate. Two kinds  of modification may be used, separately or jointly: considering the actual reradiation  pattern of finite-size facets at finite wavelengths55 and considering the effect of wave - length on establishing the effective number of facets.56 Thus, the scatter from a facet  may actually occur in directions other than that requiring that angle of incidence equal  angle of reflection. Figure 16.5 illustrates this. 
 SIGNAL  % FIELD  CONCENTRATED  AS DESIRED  TOWARD THE CENTER OF THE FEED APERTURE 4HIS SHAPING OF THE SUM 
 From the output  of the IF amplifier the signal is split into two channels. One is denoted I, for in-phase channel.  The ottler is denoted Q, for q~tadrature charrt~el, since a 90" phase change (n/2 radians) is  two detectors to be 90" out of phase. 
 18.2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 This chapter does not cover the Type I short-range specialized SBR systems  reviewed in earlier editions, such as terminal guidance or rendezvous radars. Also not  covered are Type III SBRs, such as multi-spacecraft systems for space-based radar  surveillance of the Earth’s surface or airspace. (Although these large SBR concepts are  interesting in principle, their implied costs remain a disincentive, particularly if their  erstwhile sponsors expect their performance to approach the current state-of-the-art in  airborne search or surveillance radars.) Except for the mention of a few basic concepts,  this chapter does not delve into the extensive subjects of orbitology, implementation  of space-qualified hardware, nor system integration and test, for which the interested  reader is directed to standard references.3,4 Basic Orbit Characteristics. 
 E. Wimperis, then Director of Scientific Research at  the Air Ministry. In the last days of 1934, pressed by  Dowding (at that time Air Member for Research and  Development of Air Council) to bring new scientific aid  to the stark problem of protecting Britain’s skies and  shores in the event of war, he admitted that the task  should not be the responsibility of any one man, but  that the finest team of experts available should be called  together. 
 FIELD PATTERN HAS BEEN STUDIED EXTENSIVELY AND IS WELL DOCUMENTED IN THE LITERA 
 66, McGraw-Hill Book Company, New York, 1948.  61. Symonds, M. 
 Savill: Rear Port Displays: Their Advantages, Limitations, and Design  Problems for Radar Applications, International Conference on Radar-Present and Future, Oct. 23-25.  1973, London, IEE Conference Publication no. 
 Since the two ways in which an error might be made are (I) false alarm and (2) missed  detection, the of ari error is.  where p(N) and p(SN) = a priori probabilities of obtaining noise and signal-plus-noise, re-  spectively [p(N) + p(SN) = 11  p,, = conditional probability of a false alarm, given that noise is present  J p, = conditional probability of a miss, given that signal 1s present (a, B  are often used in mathematical references for pf, and p,)  The a priori probability is the probability of obtaining either noise alone or signal-plus-noise  before the detection decision is made. These probabilities must be known beforehand in the  Ideal Observer. 
 11.13c, is obtained with noise or pseudonoise waveforms. The width of the spike at the  center can be made narrow along the time axis and along the frequency axis by increasing the  bandwidth and pulse duration, respectively. However, the plateau which surrounds the spike is  more complex than illustrated in the simple sketch. 
 The thresholds for fiJters 3 through 7 are obtained from the mean level of the  signals in the 16 range cells centered around the range cell of interest. Both a mean-level  Filter number 5 6  pr f -I  prf -2  Aircraft aliases 8  0 2 3 4 5  True  aircraft  velocity  Radial velocity Figure 4.28 Detection of aircraft in  rain using two prf's with a doppler  filter bank, illustrating the effect of  doppler foldover. (From Muehe,43  Courtesy IEEE.) . 
 (11.16) and (11.28) and by applying the Schwartz inequality. It is a  consequence of the Fourier-transform relationship between a time waveform and its spectrum  and may be derived without recourse to noise considerations. The use of the word "uncer­ tainty" is a misnomer, for there is nothing uncertain about the "uncertainty" relation of  Eq. 
 TION FORM OF THE $3$  WHICH MAY FURTHER IMPROVE RAINFALL ESTIMATION !ND  SELF  CONSISTENCY CONSTRAINTS OF THE POLARIMETRIC PRECIPITATION COVARIANCE MATRIX IMPOSE  RELATIVELY STRICT BOUNDS ON THE ABSOLUTE REFLECTIVITY MEASUREMENTS  ALLOWING ONE TO CALIBRATE THE REFLECTIVITY MEASUREMENT AND MAKE IMPROVED RAINFALL RATE ESTIMATES   &OR SHORT WAVELENGTH RADARS  ONE MUST CONSIDER -IE SCATTERING EFFECTS WHEN MEASUR 
 TO 
 FIES THE &- RATE !S A CONSEQUENCE  THE NOMINAL SINGLE 
 CONDUCTIVITY THERMAL PATH TO THE COOLING 
 O. Quijano, “Concept study of a 35m spherical reflector  system for NEXRAD in space application,” presented at 47th AIAA/ASME/ASCE/AHS/ASC  Structures, Structural Dynamics, and Materials Conference, Newport, RI, May 1–4, 2006. 52. 
 Ferri magnetic phase shirlers. A ferrite is a magnetizable metal-oxide insulator which contains  magnetic ions arranged to produce spontaneous magnetization while maintaining good dielec­ tric properties. 2 7 •29 In contrast to ferromagnetic metals, rerrites are insulators and have a high  resistivity which allows electromagnetic waves to penetrate the material so that the magnetic  field component or the wave can interact with the magnetic moment of the ferrite. 
  WAS AN EXISTING 5(&   TUBE 
 Any use is subject to the Terms of Use as given at the website. Bistatic Radar.  BISTATIC RADAR  23.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 The foregoing definitions are broad and traditional13–16 but are by no means uni - formly established in the literature. Terms such as quasi-bistatic , quasi-monostatic ,  pseudo-monostatic , tristatic , polystatic , real multistatic , multi-bistatic , and netted  bistatic  have also been used.17–20 They are usually special cases of the broad defini - tions given above. 
 Some  of the night-day contrasts, such as available frequencies and difference in noise level  for the same range, are evident. Also note that at night the 5-MHz lower frequency  limit does not provide coverage closer than about 900 km. It should be remembered  that this is a median SSN 50 calculation, and if consistent performance for ranges as  close as 900 km is required during nights, a lower frequency limit should be selected  to deal with periods of lower solar activity and the critical frequency distribution. 
 ENCES THE NATURE OF THE AMBIGUITY FUNCTION OF THE BURST )F THE FREQUENCIES ARE MONOTONI 
 6,  pp. 56 60. December, 1967. 
 TO 
 The output power is coupled from the stabilizing coaxial cavity. The cavity operates  in the TE011 mode with the electric field lines closed on themselves and concentric with the  circular cavity. The RF current at every point on the circumference of the cavity has the same  phase, so that the alternate slots which couple to the stabilizing cavity are of the same phase as  required for 1t mode operation. 
 Blind SAR Data-Focusing Algorithm The acquired data are the result of backscattering contribution of the ground at the SAR frequency. As a coherent illuminating source is used, the received data refer to several observations of the same scene taken in different points along the sensor platform trajectory. The radar transmitted pulses are stable in time, so the received returns show a strong azimuth correlation; several subsequent range lines in the raw data matrix contain roughly the same information so that the exploitation of coherence of the received signal can be attempted. 
 JKRO¼R TERM ACCOUNTS FOR THE PROPAGATION PHASE AND SPACE LOSS FROM THE FEED  TO THE REFLECTOR SURFACE &)'52%   'ENERALIZED REFLECTOR GEOMETRY.   2%&,%#4/2 !.4%..!3   £Ó°ÎÎ 4HE FINAL STEP IN THE 0/ 
 FACES SIMILAR TO THAT SHOWN IN &IGURE  IS SHOWN IN &IGURE   WHERE THERE ARE MULTIPLE REDUNDANT PROCESSING ARRAYS THAT CONTAIN STANDARDIZED MODULES CONNECTED IN A NON 
 Microstrip is a quasi-TEM mode transmission-line medium that  requires photolithographically defined lines on a low-loss, high-quality dielectric sub - strate. Reactive components that are necessary as impedance-matching elements can  be approximated in the microstrip format. An inexpensive reactive matching network  can be formed by using an interconnected pattern of microstrip elements. 
 THE RADAR TRANSMITTER  10.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10  4. R. J. 
 23.2; ( GR)T is the receiving antenna power  gain in the direction of the transmitter; B is the input RF bandwidth; and L is the  baseline range. For example, if the PBR exploits a typical FM broadcast transmitter located at a  50 km LOS from the receiver, PT GT = 250 kW, l = 3 m, B = 50 kHz, and L = 50 km.  Assuming a fixed receiving antenna beam tailored in elevation and covering a wide  azimuth sector, which includes the transmitter site, ( GR)T might be 8 dBi. 
 3, pp. 85 92, January. 1968. 
 NOUS WITH THE CUTOFF FREQUENCY THE SO 
 TRONS  TO SOLID 
 It does not take account of dissipative losses. The power gain, which will be denoted  by G, includes the antenna dissipative losses, but does not involve system losses arising from  mismatch of impedance or of polarization. It can be defined similarly to the definition of . 
 B. Ringel, “An advanced computer calculation of ground clutter in an airborne pulse doppler  radar,” in NAECON ’77 Record,  pp. 921–928 and reprinted in D. 
 R.. and M. B. 
 M. Greenblatt: Medium PRF Radar Design and Performance, 20th Tri-Service Radar Symp., 1974. Reprinted in Barton, D. 
 (16.2) dominates as the antenna approaches within a few beamwidths of the aircraft's ground track. In this region 4V3, 0 Vv62fd «—^ sin 2^ «-f- (16.22)A. ZA. 
 CIES 4HE FREQUENCY OF THE NEXT PULSE CANNOT GENERALLY BE PREDICTED FROM THE FREQUENCY OF THE CURRENT PULSE  &REQUENCY DIVERSITY REFERS TO THE USE OF SEVERAL COMPLEMENTARY  RADAR TRANSMISSIONS AT DIFFERENT FREQUENCIES  EITHER FROM A SINGLE RADAR EG  A RADAR HAV 
 Within this region, the target is in the main lobe of each of the two beams, and its angle is uniquely and unambiguously determined by the ratio of the echo strengths in the two beams. Outside this region the target is in the sidelobes of at least one of the beams, and its angle of incidence cannot be unambiguously estimated with the technique. In practice, sidelobe responses to a target are eliminated by the use of sidelobe blanking. 
 3.12] SPECULAR A.IJLJ DIF’FC’SE ILYII’LECTIO.Y 91 airport runways stand out clearly against the grass-covered ground between the runways. Atthe wavelength of1.25 cmthe grass isthor- oughlyrough and therunways quite smooth, resulting instrong contrast. The contrast isreduced atmuch shorter wavelengths (ordinary light), forwhich the runways aswell asthe grass appears rough. 
 Only that portion of the spectrum in the vicinity of the carrier frequencyfo is  sllown since tlie prf of a pulse-doppler radar is chosen to avoid overlap of target signals from  adjacent spectral lines (no blind speeds). Thus the prf is at least twice the maximum target  doppler-frequency. The leakage of the transmitter signal into the receiver produces the spike at  a frequency fo and the spikes at fo + nfp where 11 is an integer andf, is the pulse repetition  frequency. 
 The tracking filter updates the previous target state estimate Xk-1|k-1,  and its covariance matrix Pk-1|k-1 at time tk providing the new estimates Xk|k and Pk|k and  the values rk+1|k, bk+1|k and ek+1|k at the next time instant tk+1. The scheduler provides the  waveform to radiate Wk+1 and the threshold bk+1 to apply for target detection at tk+1. Selection of the Sampling Period. 
 22 HOW RADAR WORKS  Tuve, and other scientists had made radar possible. No  circuit then existed of any transmitter or receiver suitable  for radar as a navigational aid; nobody could even  attempt to draw up a mathematical plan. The spark  that brought the world’s first radar system out of this  gloom of academic experiment was an act of high  scientific statesmanship and courageous modesty by  H. 
 6. 10. H. 
 164 INTRODUCTION TO RADAR SYSTEMS  microwave combining circuitry.'~~~ These are called ni~rltittiodr /eCds. Tl~c iise of Itlgll~r-or~lcr  waveguide modes in monopulse feeds to generate the required patterns results in feeds that arc:  of high efficiency, compact, simple, low loss, light weight, low aperture blockage, and exczllsnt  boresight stability independent of frequency.  The greater the signal-to-noise ratio and the steeper the slope of the error signal in the  vicinity of zero angular error, the more accurate is the measi~rement of angle. 
 Sensing of Earth from Satellites , 1965,   pp. R1–R26.  93. 
 An example of the AGC portion of a tracking-radar receiver is shown in Fig. 5.5. A  portion of the video-amplifier output is passed through a low-pass or smoothing filter and fed  hack to control the gain of the IF amplifier. 
 FOOT RESOLUTION CLEARLY SHOWS THE OUTLINE OF THE CAB AND TRAILER OF THE TRUCK 6IBRATING 4ARGETS IN A 3!2 )MAGE  #ONSIDER A 3!2 OBSERVING A  SCENE THAT CON 
 A jammer whose noise energy is concentrated within the radar receiver bandwidth is  called a spot jammer. The spot jammer can be a potent threat to the radar if it is allowed to  concentrate large power entirely within the radar bandwidth. The radar systems designer must  prevent this by forcing the jammer to spread its power over a much wider band. 
 The chapter o~i radar clutter (Ctiap. 13) has been reorganized to include methods for the  detection of targets in the presence of clutter. Generally, the design techniques necessary for  ttie detection of targets in a clutter, background are considerably different from.those necessary  for detection in a noise background. 
 RIPPLE 
 Pi, X.; Freeman, A.; Chapman, B.; Rosen, P .; Li, Z. Imaging ionospheric inhomogeneities using spaceborne synthetic aperture radar. J. 
 D" WIDTH  OF  CPN WHERE CPN   PEAK 
   !PRIL   % & +NOTT  h4HE RELATIONSHIP BETWEEN -ITZNERS ),$# AND -ICHAELIS EQUIVALENT CURRENTS v  )%%%  4RANS  VOL !0 
 WAY  
 7. Meyer, M. A., and A. 
 London. 1976. 516 INTRODUCTION TO RADAR SYSTEMS  117. 
 § ©¨¶ ¸·  ; = S B AA B4r 
 POLARIZATION COMPONENTS  WHICH ARE  COMBINED BY THE SWITCH MATRIX TO SELECT HORIZONTAL  VERTICAL  OR CIRCULAR POLARIZATION . °£ä  2!$!2 (!.$"//+  -ULTIBAND MONOPULSE FEED CONFIGURATIONS ARE PRACTICAL AND IN USE IN SEVERAL SYS 
 The other two networks operate at very high frequencies and depend upon distributed pa- rameters for delay. An all-pass time-delay network18'19 is ideally a four-terminal lattice network with constant gain at all frequencies and a phase shift that varies with the square of the frequency to yield a constant delay slope. The networks have equal input and output impedances so that several networks can be cascaded to increase the differential delay. 
 The details of feed-motion scanners may be found in the literature.1 ·42•43 Many of these,  such as the Robinson, Foster,44•134 Lewis, and Schwarzchild, were developed during World  War II. Various types of lenses, pillboxes, and trough waveguides have also been used for  mechanically scanning a beam over an angular sector. Another mechanical scanner is a coaxial  line with radiating slots cut in its side.1 The inner conductor is corrugated and eccentric with  respect to the outer conductor. 
 502 THERECEIVING SYSTEM—INDICATORS [SEC, 138 TheBlocking Oscillator.—The blocking oscillator isaninductively coupled regenerative amplifier used inthe generation ofshort pulses. In thewaveform diagrams ofFig. 1319, consider themoment h. 
 L., and G. E. Carlson: Comparative Evaluat~on of Stereo Radar Techniques Us~ng Com-  puter Generated Simulated Imaginary, IEEE NAECON '73 Record, pp 220 -227, 1974. 
 The scheme ofFig. 16.13b, which uses i-flocking and i-fadding, isinconvenient because itrequiresa power amplifier. PERFORMANCE CRITERIA AND CHOICE OFSYSTEM CONSTANTS The primary objective ofmoving-target indication is,ofcourse, to attain ahigh degree ofdiscrimination infavor oftheechoes from moving targets compared tothose from fixed ones. 
 The lowest beam is made as narrow as  practical in elevation. It illuminates the low angles. No monopulse angle measurement would  be attempted with this beam. 
 Mack: Introduction to Radar Cross-Section Measurements,  Proc. IEEE, vol. SJ, pp. 
 One of the fundamental principles of many radar  beacons is that of the ‘transponder.’ Once it was estab-  lished that pulses from a radar transmitter could be  received and used to trigger automatically another pulse  transmitter with uniformly negligible time delay (not  necessarily repeating the original pulse form, nor re-  transmitting on the same frequency) it became clear  that such a ‘transponder’ could be set up at any con-  venient place and would act as a radar beacon. An  operational advantage of such a beacon is that it main-  tains ‘wireless silence’—in effect, speaking only when  being spoken to. Moreover, it is capable of being made  to respond only to certain coded sequences of pulses on  a given frequency, and to give accurate information of  | 156  . 
 Figure 9. Receiving antenna module block diagram. 125. 
 Classes of ambiguity diagrams. There are three general classes of ambiguity diagrams,  Fig. 1 1.13. 
 In actual situations one encounters target fades (changes in signal strength due to multipath propagation, blind speeds, and atmospheric conditions), false alarms (due to noise, clutter, interference, and jamming), and poor radar parameter es- timates (due to noise, unstabilized antennas, unresolved targets, target splits, PROBABILITY OF RESOLUTION . CHAPTER 9 ELECTRONIC COUNTER- COUNTERMEASURES A. Farina Radar Department Selenia S.p.A. 
 ENTRY 4HE SYSTEM WAS PROJECTED TO MEASURE THREE 
 (21.4), one obtains » _ *• o _ M D - D ot ^ 8«~ 2Z^*-T J^ "I (2L5) It will be noted that Eq. (21.5) indicates an azimuth linear resolution independent of both range and wavelength. Moreover, the result indicates that finer resolution is achievable with smaller rather than larger physical apertures. 
 The maximum gain of an antenna is related to its physical area A (aperture) by  where p = antenna efficiency and A = wavelength of radiated energy. The antenna efficiency  depends on the aperture illumination and the efficiency of the antenna feed. The product of p.4  is the effective aperture A,. 
 It is clear, therefore, that the doppler spectrum contains the in- formation necessary to measure important signal parameters. In the most general case, quadrature phase detection is used to obtain the real and imaginary parts of the complex signal envelope.8 These are usually digitized in a large number of range gates (—1000) at the radar's pulse repetition frequency. The resultant complex time series in each gate can then be processed by using a fast Fourier transform (FFT) to obtain an estimate of the doppler spectrum from which the mean velocity and spectrum variance can be obtained. 
 The AN/APY-9 radar addresses the AEW radar surveillance coverage requirements  discussed at the beginning of this chapter, utilizing a mechanically and electronically  steerable antenna located in a rotodome. There are three scanning modes of operation:  FIGURE 3.29  MTI improvement factor for a double-notch canceler  tracking two spectra as a function of the normalized spectra separation  ∆f/fr. Normalized spectral width sc /fr = 0.01. 
 AP-12, pp. 142-49, March,  1964.  144. 
 Aimaiti, Y.; Yamazaki, F.; Liu, W.; Kasimu, A. Monitoring of land-surface deformation in the karamay oilﬁeld, Xinjiang, China, using sar interferometry. Appl. 
 ¤ ¦¥³ µ´¤ ¦¥³ µ´ 
 Another important application of radar designed for the detection of weather  echoes is in airborne weather-avoidance radars, whose function is to indicate to the aircraft  pilot the dangerous storm areas to be avoided. RADAR CLUTTER 499  Radar equation for meteorological echoes.69 71 The simple radar equation is  P,G2).2a p -·--···---- r -(4n)3R4 (13.14)  The symbols were defined in Sec. l.2. 
 GER REGULAR RETURNS THAN RADARS AT OTHER ANGLES (ORIZONTALLY POLARIZED WAVES ARE REFLECTED BETTER BY HORIZONTAL WIRES  RAILS  ETC  THAN ARE VERTICALLY POLARIZED WAVES 6ERTICALLY POLARIZED WAVES ARE REFLECTED BETTER FROM VERTICAL STRUCTURES SUCH AS TREE TRUNKS  AT LEAST WHEN THE WAVELENGTH IS COMPARABLE OR LARGER THAN THE TRUNK DIAMETER )F THE GEOMETRY OF TWO RADAR TARGETS WERE THE SAME  THE RETURNS WOULD BE STRONGER  FROM THE TARGET WITH HIGHER COMPLEX PERMITTIVITY BECAUSE LARGER CURRENTS DISPLACEMENT OR CONDUCTION  WOULD BE INDUCED IN IT "ECAUSE IDENTICAL GEOMETRIES WITH DIFFERING PERMIT 
 (21.27) and (21.28).AIRCRAFT . (21.28) and (21.29) are used to evaluate the sum appearing in Eq. (21.26), one obtains <£e-i<w(2R/c - 2R1Ic] _ ££-/(2a>o/c)(2xjt' - x'2)/2RQ (21.30) Thus far, the summation index has not been defined. 
 J. Cantafio (ed.), Space-Based Radar Handbook , Chapter 5, Norwood, MA: Artech House, 1989. 28. 
 ch22.indd   9 12/17/07   3:02:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 
 Deep learning in neural networks: An overview. Neural Netw. 2015 ,61, 85–117. 
        
  RANGE FROM  M BY  M  SINGLE LOOK   
 3.14 antenna pattern isdiscussed inSec. 2.5, where anexpression forthe ideal antenna pattern isderived from anapproximate expression foru: u=(Ra)(L) sin0. (34) InSec. 
 SCAN IS A  REPRESENTATION USUALLY IN GRAYSCALE OR COLOR 
 (13.14)  can he written  (13.16)  In the above. the relationship G = n2/0n<Pn for a gaussian beamshape69 was substituted. The  har over 11. 
 wrote the paper. Funding: This work was supported in part by the National Natural Science Foundation of China (NSFC) under Grant Nos. 61501477 and 61171123 and in part by the International Science and Technology Cooperation Program of China (ISTCP) under Grand No. 
 If the radome surface absorbs moisture it can seriously degrade its performance in rain.  Colien and Smolskil l9 attribute most of the measured loss in the Bell Telephone air-inflated  radome at Andover, Maine to this effect. In immersion tests, the Hypalon-coated Dacron  fabric of the Andover air-inflated radome was found to absorb 13.2 percent water while the  fibrous glass-reinforced laminate of rigid radomes absorbed less than 0.5 percent. 
 LESS SERVICES HAVE REDUCED THE AVAILABLE SPECTRUM AVAILABLE TO MICROWAVE RADARS TO THE POINT WHERE IT IS LIMITING PERFORMANCE  4HE SENSITIVITY OF MICROWAVE RADARS IS LIMITED BY RECEIVER NOISE  BUT THE SENSITIVITY OF  (& RADARS IS LIMITED BY EXTERNAL NOISE THAT ENTERS THE RECEIVER THROUGH THE ANTENNA 4HIS EXTERNAL NOISE IS DUE NOT ONLY TO NATURAL MECHANISMS SUCH AS THUNDERSTORMS BUT TO THE SIG 
 4.2. The net loss LT used to com - pute SNR for a target is generally higher than the net loss LC used to compute CNR  in Eq. 4.2. 
 AES , vol. 34, pp. 1271–1292, October 1998. 
 Geophys. Res., vol. 82, pp. 
 ! "" !   # ' !  ( ! !         !    &!$!#$!  &!"  !"#    #!! .   30!#% 
 Schafer, Digital Signal Processing , Englewood Cliffs, NJ: Prentice-Hall,  Inc., 1975, p. 223. 29. 
 Any use is subject to the Terms of Use as given at the website. Bistatic Radar.  BISTATIC RADAR  23.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 The term fB also defines the doppler beat frequency , which is produced by mix - ing the target’s doppler with the direct path signal in the receiver. Willis1 provides an  expression for fB when all three sites are in motion. 
 1R.Bowman, J.J.,T.B.A.Senior,andP.L.E.Uslengh: ..Electromagnetic andAcoustic Scattering by SimpleShapes," North-Holland Publishing Co.,Amsterdam, andJohnWiley&Sons,Inc.,NewYork, 1969. 19.Ruck,G.T..D.E.Barrick, W.D.Stuart,andC.K.Krichbaum:" RadarCross-Section Handbook," (2 vols.),Plenum Press,NewYork,1970. 20.Siegel.K.M.•F.V.Schultz, B.H.Gere,andF.B.Sleator:TheTheoretical andNumerical Determina­ tionoftheRadarCrossSectionofaProlateSpheroid, IRETrans.,vol.AP-4,pp.266-275, July,1956. 
 The primary objectives of the SAR experiment on Seasat-A included (a) to obtain radar imagery of ocean wave patterns in deep oceans, (b) to obtain ocean wave patterns and water-land interaction data in coastal regions, and (c) to obtain radar imagery of sea and fresh-water ice and snow cover. The secondary objec- tives included (a) to obtain radar imagery of land surfaces; (b) to obtain data for mapping of the earth's surface; (c) to obtain data for estimates of land and sea surface roughness, ice type, differentiation of surface materials, vegetation, and landforms; (d) to obtain data for monitoring changes in the environment; (e) to obtain a demonstration of all-weather, day-night measurement capability; and (/) to obtain data useful for designing future high-resolution spaceborne radar sys- tems. GEOs-3. 
 AES-7, pp. 1170-1 178, November, 1971.  44. 
 The “nadir line” shown  in Figure 17.4 is the locus of subradar points as the platform flies along its path. FIGURE 17.4  Range and velocity contours on the Earth’s surface:  (a) Collection geometry. ( b) Constant- range contours are concentric circles with the subradar point at the center; “nadir line” refers to the locus of  subradar points. 
  WAS THE FIRST MISSION TO IMPLEMENT THEN TO PERFECT  OPERATIONAL 3CAN3!2  WHICH HAS BEEN ADOPTED AS A STANDARD MODE ON MANY SPACE 
 The exact methods are restricted to relatively simple or relatively small objects in the Rayleigh and resonant regions, while most of the approximate methods have been developed for the optics region. There are exceptions to these general limitations, of course; the exact solutions for many objects can be used for large bodies in the optics region if one uses arithmetic of sufficient precision, and many of the optics ap-AZlMUTH ASPECT ANGLE (degrees) (a)ELEVATION ASPECT ANGLE (degrees) (b) AZIMUTH ASPECT ANGLE (degrees) (c)ELEVATION ASPECT ANGLE (degrees) (d)<r (dB above 1 ft2) o- (dB above 1 ft2) o- (dB above 1 ft2) o- (dB above 1 ft2) o (dB above 1 ft2) o- (dB above 1 ft2) . (b) FIG. 
 Stimson, Introduction to Airborne Radar,  2nd Ed. Mendham, NJ: SciTech Publishing, Inc.,  1998, pp. 506–507. 
 Cliadwick. R. B.. 
 Contreras, W. J. Plant, W, C. 
 3. James, H. M., N. 
 Teague, G. L. Tyler, and R. 
 The lane width of streets is normally around 3 – 3.4 m.  Thus there is an angular range of ±5°, which must be additionally acquired  during curving.  Presently the antenna patterns are not adjusted with the turning of the steering wheel. 
 For N = 255, the peak sidelobe varies from  -21.3 dB to -22.6 dB, instead of the -24 dB predicted. 29  The binary codes generated in this manner fit many of the tests for randomness. (Ran­ domness, however, is not necessari.ly a desirable property of a code used for pulse compres­ sion.) The number of ones in each sequence differs from the number of zeros by at most one  (the balance property). 
 10.10  Other Passive Linear-F M Devices  ......................  10.12  Voltage-Controlled O scillator  .............................  10.15  10.6 Phase-Coded Wave forms  ...................................... 
 Intermediate conditions areillustrated inFigs. 3.31 and 3.32, which show two Japanese towns asseen with medium-resolution. SEC. 
 LATIONS %XAMPLES OF SUCH UNDESIRED SINUSOIDAL MODULATIONS ARE IN 
 K.: FFT Doppler Filter Performance Computations, NRL Memorandum Report 2744, Naval  Researcf, Laboratory, Washington, D.C., March, 1974.  40. Jensen. 
 Ateach end of thecathode there isanend shield, orhat H,whose purpose istoprevent electrons from leaving thecathode structure inadirection parallel tothe axis ofthemagnetron. These end shields must bekept atatemperature toolow tocause theemission ofelectrons.. 322 THEMAGNETRON ANDTHEPULSER [SEC.10.1 The dimensions oftheinteraction space depend upon thewavelength and voltage atwhich the magnetron istooperate and also upon the number ofresonant cavities, oroscillators. 
 J., E. N. Leith, C. 
 TION MEASUREMENTS  /N THE OTHER HAND  IF THE SIGNAL IS WEAK  NOISE ENHANCEMENT WILL  DOMINATE THE WHITENING PROCESS AND ANY ADVANTAGE IS LOST (IGHLY IMPORTANT IS THE FACT THAT THE TRANSMIT PULSE AND ITS BANDWIDTH ARE NOT CHANGED CONS EQUENTLY  INCREASED FRE 
 JAMMING MODE 4HI S CAN BE OBTAINED BY  e  /F COURSE  SUCH RADARS HAVE TO SEE ALSO TARGETS AT SHORTER RANGES WHERE CLUTTER ECHOES CAN MASK THE TARGETS ECHO FOR  THIS REASON  ALL LONG RANGE CIVIL AIR TRAFFIC CONTROL RADAR EMPLOY DOPPLER PROCESSING.   %,%#42/.)# #/5.4%2 
 (Reprinted in Kovaly.15) 14. C. W. 
 Htheechofromstationary clutter onthefirstpulseisrepresented t>yAcoswtandfromthesecondpulseisAcos(wt+!itt», where!itt>isthechangeinoscillator phasebetween thetwo,thenthedifference between the twoaftersubtraction isAcoswt-Acos(wt+tic/»=2Asin(tic/>/2)sin(wt+!ic/>/2).For smallphaseerrors,theamplitude oftheresultant difference is2Asintic/>/2::::Atitt>.Therefore thelimitation ontheimprovement. fa~tordue.tooscillator instability is ..{ ,,~" :I, ' ,;'1' I=(tic/>)2(4.17). This woiild apply to tile coho locking or to the phase change introduced by a power amplifier. 
 TUDES WITHIN THE RANGE BETWEEN  6 TO  6 AND PULSE WIDTHS WITHIN THE RANGE BETWEEN  PS TO  NS AT A PULSE REPETITION INTERVAL OF BETWEEN SEVERAL HUNDRED MICROSECONDS TO ONE MICROSECOND  DEPENDING ON THE SYSTEM DESIGN 4HE IMPULSE GENERATOR IS GENERALLY BASED ON THE TECHNIQUE OF RAPID DISCHARGE OF THE STORED ENERGY IN A SHORT TRANSMISSION LINE 4HE MOST COMMON METHOD OF ACHIEVING THIS IS BY MEANS OF A TRANSISTOR OPERATED IN AVALANCHE BREAKDOWN MODE USED AS THE FAST SWITCH AND A VERY SHORT LENGTH OF TRANSMISSION LINE )T IS QUITE FEASIBLE TO GENERATE PULSES OF SEVERAL HUNDRED K6 ALBEIT AT LONG REPETITION INTERVALS 4HE OUTPUT FROM THE RECEIVE ANTENNA IS APPLIED TO A FLASH !$ CONVERTER OR A SEQUENTIAL SAMPLING RECEIVER 4HE LATTER NOR 
 € σ∝ r'=0r ∫ d ϕ=02π ∫df d=f(r',ϕ,θ),θ=aspect angle (11.19)    . Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 103     The result of the integration reads:   € σ=r2πcos2θJ124πr λsinθ         (11.20)   For orthogonal incidence one obtains the following from Equation (11.20)   € σ=4π3r4 λ2=G⋅AW (11.21)  Where A w = surface of the disk and the disk is assumed to be infinitesimally  thin.  A disk with  a diameter of 1 m has a Radar backscattering cross -section of 8610 m2 with a frequency of 10  GHz. 
  
 94. Mrstik. A. 
 39,  pp 172 176, March. 1970.  79. 
 ANALOG $!  CONVERTER 4HE FREQUENCY  RESOLUTION IS DEPENDENT ON THE NUMBER OF BITS AND THE CLOCK FREQUENCY OF THE PHASE ACCUMULATOR 4HE OUTPUT FREQUENCY IS GIVEN BY   F-FF .OUTCLK F    WHERE  -F   FREQUENCY WORD  INPUT TO THE PHASE ACCUMULATOR  FCLK   PHASE ACCUMULATOR CLOCK FREQUENCY  .E   NUMBER OF BITS OF PHASE ACCUMULATOR ,INEAR &- OR CHIRP WAVEFORMS ARE GENERATED BY APPLYING A CONSTANT CHIRP SLOPE  WORD DIGITIZED CHIRP SLOPE REPRESENTATION  TO THE INPUT OF THE FREQUENCY ACCUMULATOR  CREATING A QUADRATIC PHASE SEQUENCE AT THE OUTPUT OF THE PHASE REGISTER 0IECEWISE 
 Asecond range ofOto4000 ftisobtained byreducing Ajto 4Me/see. This completes themajor specifications, except forthepower. Prac- tically speaking, power must bedecided onthe basis ofexperience, calculations ofavailable power and thermal noise power being quite useless since, inpractice, the limitation isnot thermal noise but micro- phonics, etc. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 19.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 mass reached about 10 to 20%, the attenuation was about twice that of a completely  melted particle. 
 The underestimation can be reduced via LS on the support. The missed detections can be reduced when more information is adopted. In the next section, we will propose a novel method for WASAR subaperture imaging. 
 The  monostatic-radar signal increases quite rapidly as the target approaches the radar because of  the inverse relationship between the echo signal P, and R4 [Eq. (14.35)]. The bistatic radar  signal also increases as either end of the fence is approached since the echo signal is inversely  proportiodal lo D:D: [Eq. 
 The echoes from cavities such as intake ducts, exhaust ducts, and  cockpits are large and tend to persist over aspect angles as wide as 45 ° or 60 °. This is  because most of the internal duct surfaces (i.e., compressor stages and turbine faces)  are metallic, and any radar wave that finds its way into the structure will likely find  its way back out toward the radar. This is also true of internal reflections from within  cockpit canopies. 
 The zeros are controlled by the feedforward paths, and the poles by the feedback paths. Velocity response shaping can be accomplished by the use of feedforward only, RESPONSE (dB) 14.4 HITS PERBEAMWIDTH Z-PLANE TRIPLE-DELAYCANCELER POLE - ZERO LOCATION SHOWN FOR K|= 0.98, K2 = 0.7I, K3=-0.25, K4 = 0.500ONE ZEROATORIGIN TWO ZEROS ON UNIT CIRCLE £ = ARC COS K1 ONE POLEON X AXIS DISTANCE FROM CENTER =K4 TWO POLES AT DISTANCE OFx^7KJ FROM CENTER AT ANGLES OF 10 9 = ARC COS -^- 2V1K?_e_o_ _ (Z-I) (Z2-2K| Z-H) "em ~ (Z-K4)(Z2-K2 Z-K3) . HITS PER BEAMWIDTH FIG. 
   PP n    ! 2 %DISON  h!N ACOUSTIC SIMULATOR FOR MODELING BACKSCATTER OF ELECTROMAGNETIC WAVES v 0H$  DISSERTATION  5NIVERSITY OF .EW -EXICO  !LBUQUERQUE    " % 0ARKINS AND 2 + -OORE  h/MNIDIRECTIONAL SCATTERING OF ACOUSTIC WAVES FROM ROUGH SUR 
 The 30-Mc/sec i-fsignal from theconverter isamplified bysixstages, gain control being applied tothe first three. The i-fbandwidth isabout 3Me/see between half-power points. The output ofthedetector, a6AC7 connected asadiode, isapplied tothefirst video stage. 
 The factthat asignal ofthesame intensity isreceived from atarget at anyposition ononesuch contour does notdepend ontheinverse-square laworany other lawofpropagation butonly ontheReciprocity Theorem.. 56 THERADAR EQUATION [SEC. 2.14 and adiffusion ofthe vapor upward into the overlying airmass. 
 The accuracy of this range measurement  is dependent upon the linear FM ranging slopes. Alert/Confirm.  The beam agility of ESA-based radars allows the use of sequen - tial detection techniques.58 A simplification of such techniques is known as Alert/ Confirm.59,60 The goal of Alert/Confirm is to provide high sensitivity while managing  false alarms and minimizing the search frame time. 
 27. Woodward, P. M., and I. 
 LAW DETECTORS v  0ROC  )%%%  VOL   PP n  *UNE    0 3WERLING  h-AXIMUM ANGULAR ACCURACY OF A PULSED SEARCH RADAR v  0ROC )2%  VOL   PP n   3EPTEMBER    ' 6 4RUNK  h3URVEY OF RADAR !$4 v .AVAL 2ES ,AB 2EPT   *UNE      ' 6 4RUNK  h#OMPARISON OF TWO SCANNING RADAR DETECTORS 4HE MOVING WINDOW AND THE FEEDBACK  INTEGRATOR v )%%% 4RANS  VOL !%3 
 Consequently, one would prefer to use a large number of reference cells. However,  if one does this, the homogeneity assumption (i.e., all the reference cells are statisti - cally similar) might be violated. A good rule of thumb is to use enough reference cells  so that the CFAR loss is below 1 dB and at the same time not let the reference cells  extend over a range interval that violates the homogenous background assumption. 
  N      N        x   -  
 Satoh, K. Furukawa, M. Koiima, H. 
   42!#+).' 2!$!2   °{Ç 4HIS APPROACH CAN REDUCE ERRORS BY TWO EFFECTS &IRST  AS OBSERVED IN &IGURE   THE  MAGNITUDE OF THE ELEVATION MULTIPATH ERROR REDUCES IN DIRECT PROPORTION TO THE BEAM 
 S. Bol'shakov: "Questions of the Statistical Theory of Radar, vol. II," chaps 10 and  11. 
 Ulaby, “8–18 GHz radar spectrometer,” University of Kansas, Remote  Sensing Lab., vol. TR 177-43, Lawrence, September 1973.  96. 
 POLE INTEGRA 
 The crystals require an external magnetic field, and the band- width and center frequency increase with the field strength. The delay of a YIG is determined by the crystal length. The maximum crystal length is limited to about 1.5 cm, corresponding to a delay of about 10 jxs. 
 Cao, N.; Lee, H.; Zaugg, E.; Shrestha, R.; Carter, W.E.; Glennie, C.; Lu, Z.; Yu, H. Estimation of Residual Motion Errors in Airborne SAR Interferometry Based on Time-Domain Backprojection and Multisquint Techniques. IEEE T rans. 
 The shortcomings were corrected, and the first radar echoes obtained at  NRL using pulses occurred on April 28, 1936, with a radar operating at a frequency of  28.3 MHz and a pulse width of 5 ,US. The range was only 24 miles. By early June the range was  25 miles. 
 The mathematical derivation of the collapsing loss, assuming a square-law detector. may  be carried out as suggested by Marcum10 who has shown that the integration of m noise  pulses. along with 11 signal-plus-noise pulses with signal-to-noise ratio per pulse (S/ N)n, is  equivalent to the integration of m + n signal-to-noise pulses each with signal-to-noise ratio  n(S/ N),, /(m + 11 ). 
 The following two sections will describe methods ofproviding directly viewed electronic indices; auxiliary optical aids have already been described inChap. 7. 13.11. 
 If the temperatiire T is taken to be  290 K, which corresponds approximately to room temperature (62"F), the factor kT is  4 x lo-" W/Hz of bandwidth. If the receiver circuitry were at some other temperature, ttie  thermal-noise power would be correspondingly different.  A receiver with a reactance input such as a parametric amplifier need not have any ::!  significant ohmic loss. 
 The feed, transmission line, and supporting  structure intercept a portion of the. radiated energy and alter the effective antenna pattern.  Some of the energy reflected by the paraboloid enters the feed and acts as any other wave  traveling in the reverse direction in the transmission line. 
 CAVITY 3 
 TYPE BASE REGION HAS BEEN DIFFUSED OR IMPLANTED INTO THE COLLECTOR  THE  . 
 The  output delivers 2 × N elements, as demonstrated in Figure 8.26.  - . Radar System Engineeri ng Chapter 8 – Pulse Radar  69     + + + + + + - - + + - + - + - - - - - - + + - - + - + - C  + + + + + + - - + + - + - + C  -   - - - - - + + - - + - + - C  +     + + + + + - - + + - + - + C  -       - - - - - + + - - + - + - C  +         + + + + + - - + + - + - + C  +           + + + + + - - + + - + - + C  -             - - - - - + + - - + - + - C  -               - - - - - + + - - + - + - C  +                 + + + + + - - + + - + - + C  +                   + + + + + - - + + - + - + C  +                     + + + + + - - + + - + - + C  +                       + + + + + - - + + - + - + C  +                         + + + + + - - + + - + - +n -n n n n nn n n n-n -n -nC Cn -n  1 0 1 0 1 0 1 0 1 0 1 013 0 1 0 1 0 1 0 1 0 1 0 1t t  Figure 8.25  Signals at the summing unit of the Barker Decoder for N=13. 
 Van Nostrand Company, Princeton, N.J., 1965. 11. Steinberg, B. 
   05,3% $/00,%2 2!$!2   {°xÎ  $ -OONEY AND ' 2ALSTON  h0ERFORMANCE IN CLUTTER OF AIRBORNE PULSE -4)  #7 DOPPLER AND PULSE  DOPPLER RADAR v IN   )2% #ONVENTION 2ECORD   VOL   PART     PP n AND REPRINTED IN  $ + "ARTON   #7 AND $OPPLER 2ADARS   3ECTION 6) 
 contributed to the organization of the paper and also the experimental analysis. Funding: This research was supported by the National Natural Science Foundation of China (61331020). Acknowledgments: We would like to thank the anonymous reviewers for carefully reading the manuscript and providing valuable comments and suggestions. 
 Target motion is described by  X(tk+1) = f(tk) X(tk) + A(tk) + Ap(tk) (7.22) where X(tk) is the target state at time tk, consisting of position and velocity components;  f(tk) is a transition matrix that moves the target linearly over an elapsed time, Tk = tk+1 − tk,  from time tk to time tk+1; A(tk) is the target state change due to an unknown acceleration  caused by a maneuver or atmospheric drag; and Ap(tk) is target state change due to a known  acceleration that can be corrected, such as gravity for a falling object or Coriollis accelera - tion. The components of the state vector and transition matrix for this problem are44  X tx t x t y t y t z t z ttkk k k k k kk ( )( )( ) ( ) ( ) ( ) ( )( =• • •φ) )=1 0 10 00 00 00 0 0 00 0 10 10 00 0 0 00 00 00 0 10 1T T Tk k k  (7.23) The unknown acceleration A(tk) is zero-mean and is characterized by its covariance  matrix Q(tk). If one views the unknown maneuver as a white-noise process with spec - tral density q g/Hz, then the acceleration is sampled by each radar detection producing  a discrete covariance matrix:  Q t qT T T T T T kk k k k k k( )/ / / /=3 2 2 33 2 20 0 0 00 0 0 0 0 00 0 32 2 2 3 2 22 20 0 0 0 0 00 00 00 03 2 2/ / / / /T T T T T Tk k k k k k (7.24) The observation equation relates the actual radar measurements Yk at time tk to the  target state  Yk = h(X(tk)) + nk (7.25) where nk is the radar measurement noise having a covariance matrix  ℜ =kr Dσ σ σ σθ ϕ2 2 2 20 0 0 0 0 0 0 0 0 0 0 0 (7.26) ch07.indd   28 12/17/07   2:14:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 FORM 34!0 ON SIGNALS BEFORE OR AFTER DOPPLER FILTERING )N ADDITION  THE OVERALL TRANS 
 Thus,itcausestargetstobemissed.Furthermore, theoperator isusually givennoindication thattheremaybemisseddetections. InradarswithasimpleCFAR, interference orhostilejamming canlowerthesensitivity oftheradarwithouttheoperator even beingawarethatitishappening sincethejamming isnotvisibleonthescope.Thussome meansshouldbeincluded toinformtheoperator whenthedetection probability hasbeen lowered because oftheCFARaction. Itisbettertoincorporate inthedesignofaradarmeansforeliminating unwanted signals heforetheyentertheADTthantodependonCFARtoeliminate them.Examples ofsignal processing techniques thateliminate unwanted signalswithoutaseverepenaltyindetectability includeMTIforclutterechoes,thelowsidelobe antenna and/orsidelobe cancelers forjam­ mingnoise,andthesidelobeblankerortheprffilterforpulseinterference. 
 SIGMA ELLIPSE !S SHOWN IN THE FIGURE  THE PERPENDICULAR INTERCEPT MAY NOT LIE INSIDE THE ROAD SEGMENT AND WILL BE DISCARDED 4HE MINIMUM DISTANCE FOR VALID ROAD SEGMENT DISTANCES WILL BE SELECTED AS THE '-4 LOCATION )F THE ECCENTRICITY IS GREATER THAN THE THRESHOLD  THE ROAD SEGMENTS THAT HAVE A MAJOR ELLIPSE AXIS INTERCEPT INSIDE  SIGMA ARE COMPARED  AND THE MINIMUM DISTANCE IS SELECTED /BVIOUSLY  SOME OTHER SCREENING MUST ALSO BE APPLIED &OR EXAMPLE  SOME ROADS CANNOT SUPPORT HIGH SPEEDS AND TANKS DO NOT HAVE TO BE ON ROADS ! COMMON 3!2 
 38.  pp. 1053-1056, September, 1950. 
 The two-antenna scheme is difficult to mechanize, and additional errors can occur if the antennas are mounted one above the other because of antenna field variations. These variations are caused by the difference in physical location due to vertical displacement, the effect of the different near-field environments, and fabrication errors. Furthermore, the PRF is effectively cut in half by having to receive during the unique alternate transmission-path configurations. 
 The Kalman filter 78 is similar to the classical cx.-{3 tracker except that it inherently pro­ vides for the dynamical or maneuvering target. In the Kalman filter a model for the measure­ ment error has to be assumed, as well as a model of the target trajectory and the disturbance or  uncertainty of the trajectory. 81 Such disturbances in the trajectory might be due to neglect of  higher-order derivatives in the model of the dynamics, random motions due to atmospheric  turbulence, and deliberate target maneuvers. 
 Green diamonds denote slave images. 216. Sensors 2019 ,19, 743 3.2. 
 The maximum  slope occurs at a beam crossover of about 1.1 dB.  Automatic gain control (AGC) is required in order to maintain a stable closed-loop servo  system for angle tracking. 1 ·2 The AGC in a monopulse radar is accomplished by employing a  voltage proportional to the sum-channel IF output to control the gain of all three receiver  channels. 
 13.3SEACLUTTER Theechofromthesurfaceoftheseaisdependent uponthewaveheight,windspeed,thelength oftimeandthedistance (fetch)overwhichthewindhasbeenblowing, direction ofthewaves relativetothatoftheradarbeam,whether theseaisbuilding uporisdecreasing, thepresence ofswellaswellasseawaves,andthepresence ofcontaminants thatmightaffectthesurface tension. Theseaechoalsodepends onsuchradarparameters asfrequency, polarization, grazingangle,and,tosomeextent,thesizeoftheareaunderobservation. Although thereis muchthatisknownaboutthenatureofseaclutter,thequantitative, andsometimes eventhe qualitative, effectsofmanyofthe'abovefactorsarenotknowntothedegreeoftendesired.The relativeuniformity oftheseaovertheoceansoftheworldmakesiteasiertodealwithsea clutterthanwithlandclutter,butitisdifficulttocollectdataatseaunderthecontrolled and reproducible conditions necessary toestablish quantitative causalrelationships. 
 SAMPLING RATE 4HE  )T  COMPONENT MODULATES A n CARRIER SIGNAL  AND THE  1T  COMPO 
 ch24.indd   59 12/19/07   6:01:16 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 This is on the order of 75 times smaller than the sci - ence requirement of 120 meters azimuth resolution. It followed that single-look 120-m  data could be collected by operating the radar only 1/75 of the time. If NL looks were  required, then the implied operating duty factor would be NL/75, larger by a factor of  NL. 
 TIMES IN DOPPLER  THE ERRORS IN EACH OF THESE TARGET PARAMETERS MUST BE CONSIDERED ON MOST ERROR BUDGETS 4HE REST OF THIS CHAPTER WILL PROVIDE A GUIDE FOR DETERMINING THE SIGNIFICANT ERROR SOURCES AND THEIR MAGNITUDES )T IS IMPORTANT TO RECOGNIZE WHAT THE ACTUAL RADAR INFORMATION OUTPUT IS &OR A  MECHANICALLY MOVED ANTENNA  THE ANGLE 
  IN (ENDERSON AND ,EWIS   IN THE FORMER ,ET US CONSIDER A PARTICU 
 13.5 for sea state 1 by proper  selection of the parameters. Other pdf's that have been suggested for approximating non-  Rayleigh sea clutter include the Ricean13 [Eq. (2.27)], the chi-square1 [Eq. 
 34-37, April, 1976.  69. Acker, A. 
 The coherent integration  time is maximized within the limits of the maximum expected target radial acceleration.  VS is optimized for Swerling I and III target amplitude fluctuation statistics and the  cumulative probability of detection of incoming targets over several search frames. High-PRF Range-While-Search. 
 In these diagrams a curve is drawn in a time-frequency plane to represent each of the signals of interest. A typical plot, that for a sinusoidally modulated altimeter, is shown in Fig. 14.15. 
 6.9. At the  left-hand portion of the figure is the cathode, which emits a stream of electrons that is focused  into a narrow cylindrical beam by the electron gun. The electron gun consists of the cathode. 
 ONLY CONTROL AT  EACH ELEMENT . 
 Ithas been found very profitable toadjust variations inthe effective guide. 294 ANTENNAS, SCANNERS, AND STABILIZATION [SEC. 9.13 width (orthe phasing) bymeans ofscrew adjustments onthetoggles of the squeeze mechanism. 
 The reflector  surface is defined as  zy ff = −2 4 (12.23) where z is the distance from the focal plane, f is the focal length of the cylindrical  reflector, and y is the horizontal dimension. For the parabolic cylinder, the surface does  not vary with x, the height. The feed is generally on the focal line, and in many ways,  the design of parabolic cylinder reflectors is similar to that of paraboloidal reflectors. 
 By  employing the principle of multipacting, a recovery time as short as 5 ns is possible.44•51 A  multipactdr is a vacuum tube which contains surfaces capable of a high yield of secondary  emission upon impact by an electron. Th·e secondary emission surfaces are biased with a d-c  potential. The presence of RF energy causes electrons to make multiple impacts to generate by  secondary emission a large electron cloud. 
 J. Anderson, “Estimating the frequency interval of a regularly spaced multi- component harmonic line signal in colored noise,” in Defence Applications of Signal Processing ,  D. A. 
 The altimeter is an essential flying instrument, and for  many years the only indication of height was the reading  of an aneroid barometer which had been set before  take-off to the height above sea-level of the airfield from  which the flight started. Even if the weather conditions  did not change during the flight the best that could be  expected was that while over water or land at sea-level  the aneroid would register ‘true clearance.’ The same  reading would be obtained in level flight if} a few  minutes later, the aircraft flew over mountain-peaks  10,000 feet high, with disastrous results if the flight  altitude were only 9000 feet. This is not a fanciful  possibility, for only too often have aircraft flown into  mountain-sides in weather so ‘thick’ that disaster was  upon them before the air-crew could take evasive action. 
 JAMMING ADAPTIVE FILTERING FOR 3!2 IMAGING v  0ROC OF )23   )NT 2ADAR  3YMP  -UNICH  'ERMANY  3EPTEMBER n    PP n  * ! 4ORRES  2 - $AVIS  * $ 2 +RAMER  AND 2 , &ANTE  h%FFICIENT WIDEBAND JAMMER  NULLING WHEN USING STRETCH PROCESSING v  )%%% 4RANS  VOL !%3n  NO   PP n   /CTOBER   , 2OSENBERG AND $  'RAY  h!NTI 
 The delay-line canceler acts as a filter to eliminate the d-c component of fixed targets  and to pass the a-c components of moving targets. The video portion of the receiver is tfividetl  into two channels. One is a normal video channel. 
 Eq. (8.10) states that the element spacing should be less than 0.54A. Note that antenna  elernetlts used in arrays are gelierally comparable to a half wavelength in physical size. 
 Shaping includes specific design configurations, such as the placement of  engine intakes, which can have large radar echoes, where they may be shielded from  the incident wave by other parts of the target. The purpose of radar-absorbing materials  (RAM) is to absorb the incident radar energy so as to minimize the energy scattered  back to the radar. Both methods have advantages and disadvantages. 
 For this reason, artificial dielectrics are often preferred when the size of the antenna is  large, as, for example, at the lower radar frequencies. Artificial-dielectric lenses may he  designed in the same manner as other dielectric lenses.  Metal-plate lens.49-5 2 An artificial dielectric may be constructed with parallel-plate wave­ guides as snown in Fig. 
 Extremely wide bandwidth can be realized. While high-power microwave radar tubes can achieve 10 to 20 percent bandwidth, solid-state transmitter mod- ules can achieve up to 50 percent bandwidth or more with good efficiency. 7. 
 13.49. When thegrid ofVIisreleased byopening the switch, itquickly rises tocutoff and anegative sawtooth begins ontheplate. The form ofthis wave ispractically independent of theload impedance, which isinthis case made upoftheinductance L,V2, and R2inseries, and thevarious capacities. 
 6RELATIVEK  WHERE K   CF IS THE WAVELENGTH   C IS THE SPEED OF  LIGHT  AND  F IS THE CARRIER FREQUENCY 7HEN THE TARGET IS MOVING AWAY FROM  THE RADAR   THE RELATIVE RADIAL VELOCITY  OR RANGE RATE  IS DEFINED TO BE POSITIVE AND RESULTS IN A NEGATIVE DOPPLER SHIFT $OPPLER RADARS CAN BE EITHER CONTINUOUS WAVE #7  o OR PULSED RADARS #7 RADARS  SIMPLY OBSERVE THE DOPPLER SHIFT BETWEEN THE CARRIER FREQUENCY OF THE RETURN SIGNAL RELATIVE TO THE TRANSMIT SIGNAL 0ULSED SYSTEMS MEASURE DOPPLER BY USING A COHERENT TRAIN OF PULSES WHERE THERE IS A FIXED OR DETERMINISTIC PHASE RELATIONSHIP OF THE CARRIER FREQUENCY BETWEEN EACH SUCCESSIVE RADIO FREQUENCY 2&  PULSE #OHERENCE CONCEN 
 and D. D. Crombie: Sea Backscatter at HF: Interpreta­ tion and Utilization of the Echo. 
 The simplest propaga - tion model is spherical spreading where the transmitter and receiver are far removed FIGURE 26.7  Elevated ductTrapping layer Elevated duct Modified refractivityHeight ch26.indd   13 12/15/07   4:53:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation. 
 SIDERED AS RECEIVING A DOPPLER 
 SUREMENT OF MISSILE AND TARGET POSITION  VELOCITY AND ACCELERATION TO ALLOW STATISTICALLY INDEPENDENT MEASUREMENTS FOR TRANSFER ALIGNMENT  AS WELL AS MISSILE STATE 
 See sea clutter Sea ice, 16.44 to 16.46, 16.48, 22.14 Sea spikes, 15. 2, 15.16 to 15.17, 15.35 Sea state, 15.6, 22.14 Sea surface, 15.3 Sea surface search, 5.30 to 5.31 Seawinds scatterometer, 18.58 Sensitivity time control (STC), 2.96 to 2.98, 6.22 to 6.24, 19.6 in CMR, 22.5, 22.13 and cosecant-squared antenna, 2. 98 in pulse doppler, 4.22 Sensitivity velocity control (SVC), 2. 
 FORM RESOLUTION  TYPICALLY  KM  #ONSEQUENTLY WHEN THESE LOW 
 The display shows a radar probability of detection in a range versus height depiction,  radar probability of detection versus range at a constant altitude depiction, and radar  probability of detection versus height at a constant range depiction. This display is  courtesy of the 84th Radar Evaluation Squadron, Hill Air Force Base, Utah. The radar  depicted is the ARSR-1E (U.S. 
 The conicalsurfaceasaradiating structure foraconformal arrayisalsoofinterestsincemissiles aresometimes ofthisshape. Theogive,whichisthetypeofsurfacefoundonthenoseofsomeaircraft, bearsa resemblance tothecone.Aconformal arrayarranged ontheaircraftnosewouldallowwide coverage, provide agoodaerodynamic shape,eliminate thedistortion ofthepatternofa mechanically scanned antenna causedbytheconventional nose-radome, andwouldpermit largerantenna apertures thantheconventional nose-antenna configuration. Thehemispheri-. 
 A convenient met hod for achieving two-dimensional scanning is to use frequency scan in  one angular coordinate and phase shifters to scan in the orthogonal angular coordinate, as was  diagrammed in Fig. 8.18. This is an example of a parallel-series feed. 
  R    WHERE R IS THE RADIAL DISTANCE NORMALIZED TO THE REFLECTOR RADIUS AND  GR  DROPS TO ZERO  AT THE EDGE 4HE USE OF THIS TAPER FUNCTION LEADS TO A SIMPLE BLOCKAGE LOSS EQUATION  0 0GR D R GR R D R$ $ 'B MB M ¯ ¯        P P B B MB M'$ $  H   WHERE G IS THE EFFICIENCY  AS GIVEN IN %Q  5SING %Q  AND %Q  LEADS  TO THE SIMPLE EXPRESSION FOR BLOCKAGE LOSS TYPICALLY FOUND IN THE LITERATURE  % %$ $ % %B MB M B M 
 When pulse-to-pulse staggering  is employed, the effect of feedback is reduced. Staggering causes a modulation of  the signal doppler at or near the maximum response frequency of the canceler. The  amount of this modulation is proportional to the absolute target doppler so that, for an  aircraft flying at VB, the canceler response is essentially independent of the feedback  employed. 
 One of the major changes is in the treatment of MTI (moving target indication) radar  (Chap. 4). Most of the basic MTI concepts Gat have been added were known at the time of tlie  first edition, but they had not appeared in the open literature nor were they widely used i11  practice. 
 WIDEBAND  OVER THE HORIZON  INSTRUMENTATION  LASER OR LIDAR   BY THE FREQUENCY BAND AT WHICH THEY OPERATE 5(&  ,  3  AND SO ON   BY THEIR APPLICATION  AND SO FORTH £°ÎÊ  ", /" Ê6  
 Since noopportunity has arisen for testing with aproper radar and with coded pukes, itisdifficult tomake an accurate assessment, but the comparative success under unfavorable conditions indicates that when properly applied the method can be satisfactory. Ifthescanning isfairly uniform but cannot besynchronized with the modulator, the method ofthe sinusoidally varied pulse (Sec. 17.5) gives very satisfactory results with aminimum ofcomplexity asproved bya reasonable amount oftesting (See. 
 Range ambiguities are avoided with a low sampling rate (low pulse  repetition frequency), and doppler frequency ambiguities are avoided with a high sampling  rate. However, in most radar applications the sampling rate, or pulse repetition frequency,  cannot be selected to avoid both types of measurement ambiguities. Therefore a compromise  must be made arid the nature of tlie compromise generally determines whether the radar is  called an MTI or a pitlsc doppler. 
 Intrapulse frequency or phase variations do not interfere with good MTI operation  provided they repeat precisely from pulse to pulse. The only concern is a loss of sen - sitivity if phase run-out during the transmitted pulse or mistuning of the coho or stalo  permits the received pulses to be significantly detuned from the intended IF frequency.  If a 1-rad phase run-out during the pulse is permitted, the system detuning may be as  large as 1/(2 pt ) Hz with no degradation of MTI performance. 
 In particular this means that the alignment be exact by 0.1°.   Sensor Blindness Recognition:  The function of the sensors must be continually checked to  ensure the immediate detection of sensor blindness due to wetness, snow, dirt, pollution, d e- fect, etc.  . 
 MATICALLY COMPARED TO !)3 DATA AND ASSOCIATED INTO A SINGLE TRACK  IF DESIRED BY THE OPERATOR 4HIS GIVES COMPLETE INDEPENDENCE TO RADAR 
 SCALE COMPOSITE SURFACE TO INCLUDE BREAKING WAVES  A PRESUMED SOURCE OF THESE RETURNS /NE OF THE LATEST OF THESE TWO 
 The Spectrum of Sea Clutter. The scattering features producing sea clutter are associated with a surface subject to several types of motion. The features may themselves be moving with small group or phase velocities over this surface while the surface, in turn, is moved by the orbital velocities of the larger waves passing across it. 
 Oceanic Eng ., vol. OE-9, pp. 309–316, December 1984. 
 On the other hand, as the radar frequency increases, the values of ΔσandΔσrincrease gradually. It is apparent that the eddy features in the SAR images become clearer at higher radar frequencies. In summary, the radar look direction mainly affects brightness variations and the visibility of eddy spirals. 
 CODED 2ADAR  7ORK HAS BEEN CARRIED OUT ON PSEUDO 
 Consequently, they will not be further considered here. Multiple Discrete PRF Ranging. Ranging by use of several (usually two or three) fixed PRFs involves sequential measurement of the ambiguous range in each PRF, followed by comparison of the measurements to eliminate ambiguities.36'37 Figure 17.14 illustrates the principle of multiple-PRF ranging for a two-PRF, high-PRF radar. 
 (Other examples of radar block diagrams can be found throughout the handbook.) The radar signal, usually a repetitive train of short pulses, is generated by the transmitter and radiated into space by the antenna. The duplexer permits a single antenna to be time-shared for both transmission and reception. Reflecting objects (targets) intercept and reradiate a portion of the radar signal, a small amount of which is returned in the direction of the radar. 
 TION  ORGANIZED BY %3! TO CHASE EACH OTHER SO THAT THEIR JOINT REPEAT VISIT WAS ONLY ONE DAY 4HIS LEAD TO THE ACCUMULATION OF A UNIQUE DATA SET  ESPECIALLY VALUABLE FOR COHERENT CHANGE DETECTION MEASUREMENTS  TWO 
 WARFARE SYSTEM !NOTHER VERSION  '/!, 
 R. Domville, ”The bistatic reflection from land and sea of X-band radio waves, Part II-   supplement,” GEC (Electronics) Ltd., Stanmore, England, Memorandum SLM2116  (Supplement), July 1969.  97. 
 18.10 with twice the dimension for the dif- ference signals in the plane of error sensing than that for the sum signal.7 A technique used by the MIT Lincoln Laboratory to approach the ideal was the 12-horn feed (Fig. 18.11). The overall feed, as illustrated, is divided into small parts and the microwave circuitry selects the portions necessary for the sum and difference signals to approach the ideal. 
 Int Symp. Ant. and Prop. 
 The  mechanism of diffraction is especially important at very low frequencies (VLF) where it  provides world-wide communications. However, at radar frequencies the wavelength is small  456INTRODUCTION TORADAR SYSTEMS refraction atthesurface,20.21 obtained witheitheramicrowave refractometer orfrommeteor­ ological measurements oftemperature, pressure, andhumidity. Animprovement totheeleva­ tionanglecorrection canbehadbymakingameasurement ofthebrightness temperature of theatmosphere withamicrowave radiometer, alongwithasurface refractive-index measurement.22Sincerefractive bending andradiometric brightness-temperature measure­ mentsbothdependontheatmospheric profile,theuseoftheradiometer provides information thataidsinthecorrection ofelevation angle.Ithasbeenestimated thatthebrightness­ temperature measurement madewitharadiometer operating nearthewatervaporabsorption lineof22GHz,alongwithameasurement ofsurfacerefractivity, canresultinanimprovement inangleaccuracy ofalmost50percent'ascompared withasurfacerefractivity measurement alone.22Theground-based microwave radiometer canalsobeusedtoprovideacorrection for theerrorintimedelayintroduced bytheatmosphere, hymaking hrightness-temperature measurements nearthe22-GHzwatervaporabsorption lineandthe60-GHza3sorption line ofoxygen.42 Ifnootherinformation isavailable, acorrection fortheelevation anglecanbehadonthe hasisoftheyearlystatistics ofthemeteorological datathatentersintoEq.(12.9)fordetermin­ ingtheindexofrefraction.22 Itispossible toautomate, bymeansofacomputer, thenecessary calculations fordeter­ miningtherefractive effectsoftheatmosphere onthecoverage oftheradar.Suchcomputa­ tionscouldbemadeattheradarsitetoprovidetheoperator withtheinformation neededto knowhowaradarisaffected bythenaturalenvironment. 
 Plant, “A new interpretation of sea surface slope probability density functions,” J. Geophys.  Res., vol. 
 Every listener to an ordinary broadcast  receiver knows that no matter how well designed is the  outfit there is always some appreciable background  hum from the power unit, or amplified hiss coming through  from the high-frequency side. Valve noise, resulting  from many combinations of mechanical and electrical  variation inside the valves, also adds to the slight back-  ground noise, but in aural reception the noise can be  filtered out, for all practical purpose, so that it does not  offend the ear. This noise presents itself on the CRT  of a radar receiver, however, and it is not so easy to trick  the eye as the ear. 
 6. H. Gautier and P. 
 Thus the design of the radar for maximum performance  will differ from that when receiver thermal noise sets the limit. In addition to satisfying the  needs for an adequate signal-to-noise ratio, there must be adequate signal-to-clutter ratio.  OTIIER RADAR TOPICS531 G,=receiving antenna gain A=wavelength a=targetcrosssection Fp=factortoaccount fortheone-way propagation effects Tc=coherent processing time No=receiver noisepowerperunitbandwidth (SfN)=signal-to-noise (power) ratio L,=systemlosses Thetransmitting andreceiving antenna gainsareshownseparately inEq.(14.22)sinceit issometimes convenient iilOTHradartohaveseparate antennas forthesetwofunctions. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.56  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 another role—as a real-time monitor of what is expected under the prevailing condi - tions, so as to alert the radar operator if a discrepancy emerges, which might be indica - tive of natural, equipment-related, or intentional events warranting attention. An issue one encounters when discussing radar performance is the choice of  performance criterion. 
 In decimation or interpolation appli - cations where the rate change factor is large (typically 8 or greater), a FIR filter  implementation might be prohibitively costly due to the large number of filter taps  that would be required. CIC filters are a class of filters introduced by Hogenauer9  that provide a very efficient means of implementing these filter functions that do  not require multipliers. Excellent descriptions of this class of filter are provided by  Lyons2 and Harris,10 which form the basis for the following discussion. 
 MODATE SUCH WEIGHTING .ADIR 2ETURN ! POTENTIALLY TROUBLESOME RANGE AMBIGUITY ARISES FROM THE SURFACE  DIRECTLY BELOW THE SPACECRAFT 4HIS NADIR RETURN IS ALWAYS RELATIVELY STRONG  PARTICULARLY  IF THERE ARE SPECULAR BACKSCATTERING COMPONENTS 3INCE ANY REALISTIC ANTENNA PATTERN HAS A NON 
 VELOCITY AMBIGUITY MITIGATION SCHEMES FOR THE ENHANCED TERMINAL DOPPLER  WEATHER RADAR v IN ST #ONFERENCE ON 2ADAR -ETEOROLOGY  3EATTLE  7!    PP n  7 7  3HRADER  h2ADAR TECHNOLOGY APPLIED TO AIR TRAFFIC CONTROL v  )%%% 4RANS #OMMUNICATIONS   VOL   NO   PP n  -AY   7 7 3HRADER  h-4) RADAR v #HAP  IN  2ADAR (ANDBOOK  - ) 3KOLNIK ED   .EW 9ORK  -C'RAW 
 87-89, American Meteorological Society, Boston, 1980. 17. Eccles, P. 
 theory predicts considerable signal fades due to interference between tlie several modes. Fades  can be of the order of 70 dB. In one example. 
 89. Gupta, D. V., J. 
 <lJ 3 g 15 ~ 300  6 w  > 3!  X 0  ~ 10 a 200  Q ti  <l) [l  5 100  0  I){)( l Peokvolloge  Ellicienc  . ---------- 200 400 600  • Average power input (Watts)  -29  --+----t--+--~--+--;28  Frequency (GHz) 25  24 5.9  +2r---.---,----,--,---,---,---,---,,---,----,  O'  C:  >­u  C  (I.) ::,  C1  ~ -1  tL ----·-------------·  I I -2~~-~~-~-~~-~-~~~  0 2 4 6 8 10 12 14 16 18 20  Peak current {A) (c) ·-----------· ·-·  800 RADAR TRANSMITTERS 197  50  40 ;:e  ~  >- 30 u (a) C  (I)  0  (;;;.  20 w  "-------10  1000°  Figure 6.6 Performance characteristics of the coaxial magnetron. 
 F. G. Bass, I. 
 QUENCY BANDWIDTHS  TO  PERCENT OF RADAR CENTER FREQUENCY  THAN LOWER FREQUENCY RADARS 4HUS  MAIN 
 j88.  April. 1959; also IRE 7'rc111s., vol. 
 44. Barghausen, A. L., J. 
 The pulse length and PRF were the same as used on ASV Mk. III. In ASV Mk. 
 TOR BASICALLY CONSISTS OF AN ENERGY STORAGE DEVICE  WHICH MAY BE A CAPACITANCE OR A PULSE FORMING NETWORK  AND A SWITCH FOR TRIGGERING THE DC PULSE 4HE SWITCH IN THE PAST MIGHT HAVE BEEN A VACUUM TUBE  THYRATRON  IGNITRON  SILICON 
 9Ê" Ê, , 2ADARS HAVE BEEN OPERATED AT FREQUENCIES AS LOW AS  -(Z JUST ABOVE THE !- BROAD 
 The point  at which ionization occurs is determined, not unnatur-  " ally, by combination of grid bias and anode voltage.  The initial anode current is very small usually, but  immediately the grid bias is reduced beyond a pre-  determined point, or the anode current is sufficiently  increased, ionization occurs and the anode-current curve  rises sharply.  In the normal thyratron-type time-base generally the  grid bias remains fixed, and the anode voltage is con-  trolled by the voltage across the condenser. 
 NOISE VOLTAGE LEVEL AT THE !$ CONVERTER  QUANTA 4HE RMS THERMAL 
 Nishikawa, and K. Tanaka, “Japanese  earth resources satellite-1 synthetic aperture radar,” Proceedings of the IEEE , vol. 79,   pp. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 • Equatorial plasma bubbles often appear after sunset and convect upward through the  F region where they contribute to strong diffuse doppler-spread scattering referred  to as spread-F.26 Detection of all targets is difficult when this effect occurs. 
 The story of how radar came to be invented must also  include the names of scientists such as Dr W. B. Lewis,  of Cambridge, who at the Malvern research centre con-  tributed to almost every step of radar progress, and of  J. 
 POWER OSCILLATOR 5NFORTUNATELY  THE POWER OUTPUT AND EFFICIENCY OF THESE DEVICES ARE  IN GENERAL  VERY LOW IN FACT  THE EFFICIENCY IS SIGNIFICANTLY LOWER THAN THAT OF THEIR TUBE COUNTERPARTS (OWEVER  #7 AND PULSED POWER OUTPUT ARE ATTAINABLE UP TO  '(Z 0EAK AND !VERAGE 0OWER ,IMITATIONS  ! FIRST 
 When ACisonly slightly greater than A,the guide-wavelength becomes very long and varies rapidly with changes inX.This greatly increases thefrequency sensitivity ofquarter- wave sections ofguide used induplexers and mixers (Sees. 115 and 11“8) and handicaps broadband design. The other extreme ofaclose approach totheboundary ofthe higher mode, corresponding toawide dimension ofnearly awhole free-space wavelength, runs into difficulty because of 1Inawaveguide beyond cutoff thevoltiage orcurrent falls offexponentially with distance, with constants exactly calculable from thedimensions andfrequency. 
 WHILE 
 With narrow beams and short pulses the inversion is relatively easy, but with the wider beams and longer pulses used in many measurements the values obtained are sometimes poorly defined. Some authors2 use a scattering cross section per unit projected area rather than per unit ground area. Figure 12.2 illustrates by a side view the difference between ground area and projected area. 
 Zeros may be anywhere .FIGURE  2.33  Nth order FIR MTI canceler block diagramb1 b2 bN Z−1Z−1y(n) Z−1bN−1 x(n)G FIGURE 2.34  One-delay canceler ch02.indd   35 12/20/07   1:44:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 TION IS APPLIED 4HE FERRITE PHASE SHIFTER IS THEN LATCHED TO THE REFERENCE PHASE n   4HIS CHANGE IN PHASE WITH A CHANGE IN CUR 
 A. C. Koivunen and A. 
 The smaller the device the more  difficult it is to dissipate the heat that is generated. Thus, the power output decreases  approximately inversely as the square of the radar frequency. The gyrotron RF power generator, however, does not have this limitation because  it does not employ slow-wave resonant microwave structures. 
 (ILL     7 ' #ARRARA  2 3 'OODMAN  AND 2 - -AJEWSKI   3POTLIGHT 3YNTHETIC !PERTURE 2ADAR    .ORWOOD  -! !RTECH (OUSE      * #URLANDER AND 2 -C$ONOUGH   3YNTHETIC !PERTURE 2ADAR   .EW 9ORK *OHN 7ILEY AND 3ONS     ' 7 3TIMSON   )NTRODUCTION TO !IRBORNE 2ADAR  ND %D  -ENDHAM  .* 3CI4ECH     # * *AKOWATZ  *R  $ %  7AHL  0 ( %ICHEL  $ # 'HIGLI A  AND 0 ! 4HOMPSON   3POTLIGHT 
 25. hfcteorological Aspects of Radio-Radar Propagation. Nary Weather Researclt Facility, Norfolk, VA,  N W R F 3 1-0660-035. 
 The elec-  tron optics is similar to the klystron. Both employ the principle of velocity modulation to  density-modulate the electron beam current. Electrons emitted by the cathode of the traveling-  wave tube are focused into a beam and pass through the RF interaction circuit known as the  slow-wave structure, or periodic delay line. 
     FOR TWO 
 The beamwidth is widened, the gain  lowered, and the network is no longer theoretically lossless. The addition of two adjacent  beanis of a Butler array, with the proper phase correction, resi~lts in an array wi~h a cosine  illumination. The crossover is lower than the lossless network, but the first sidelobe is - 23 dB  instead of - 13.2 dB. 
 SURFACE  HEIGHT MEASUREMENT ABOUT ITS MEAN VALUE (EIGHT MEASUREMENT PRECISION IS DETER 
 TEM WITH  HITS PER BEAMWIDTH AND A RATIO OF STAGGER INTERVALS OF  4HE FEED 
 If he regards stations  A and B, synchronized, as ‘blue’ stations, he merely  looks at his Gee chart of curves and notes that he is  somewhere on ‘blue 20.”  Now he turns to another pair of stations—although  let us note here for convenience that one may be simul-  taneously the second station of the first pair—é.e.,  station B—and takes a reading from this second, or  ‘red,’ group of stations. His map or Gee grid chart  will have ruled on it intersecting ‘families’ of confocal  curves, coloured blue and red respectively, and numbered  at intervals just like the contour curves or isobars of a  weather map.  . 
 The position of the larger of the two scatterers corresponds to  AOlO,, = 0, while the smaller-scatterer position is at AO/OD = + 1. Positive values of A0 corre-  spond to an apparent radar center which lies between the two scatterers; negative values lie  outside the target. When the echo signals from both scatterers are in phase (a = O), the error  reduces to a/(a + I), which corresponds to the so-called "center of gravity" of the two scat-  terers (not to be confused with the mechanical center of gravity). 
 11,1ofthisvolume.. 340 THEMAGNETRON ANDTHEPULSER [SEC. 10.5 diagram, which corresponds toamatched load, represents areasonable compromise between efficiency and frequency stability. 
 [Notethatthepeakpowerasusedttereisactually thepeakinstantaneous power,whereas thepeakpowerreferred tointhediscussion ofthe radarequation inChap.2wastheaveragevalueofthepowerovertheduration ofapulseof sinewave.TheratioRfistwicetheaveragesignf:ll-to-noise powerratiowhentheinputsignal s(t)isarectangular sine-wave pulse.]Theoutputvoltageofafilterwithfrequency-response functionH(J)is Iso(t)I= ,f:a?S(J)H(J) exp(j2nft)dfI (to.8) whereS(J)istheFourier transform oftheinput(received) signal.Themeanoutputnoise poweris (10.9) whereNoistheinputnoisepowerperunitbandwidth. Thefactor-1appearsbeforetht:integral becausethelimitsextendfrom-00to+00,whereasNoisdefinedasthenoisepoweri>er cycle ofbandwidth overpositive valuesonly.Substituting Eqs.(to.8)and(to.9)into(to.7)and assuming thatthemaximum valueofIso(t) 12occursattimet=tl>theratioRfbecomes R f~It:S(J)H(f) exp(j2nft,)df' NoJa?IH(f)12df 2 - a? Schwartz's inequality statesthatifPandQaretwocomplex functions, then Ip*PdxJQ*Qdx~IIP*Qdx12 Theequality signapplieswhenP=kQ,wherekisaconstant. Letting p*=S(f)expU2nfc1)andQ=H(J) andrecalling that fp.Pdx=fIP12dx(to.10) (10.11). 
 General.4ince beacon replies are much like radar echoes, the considerations involved inchoosing the fre- quency region forasystem inorder togetthedesired resolution aremuch the same. Ingeneral, the higher thefrequency, the better theazimuth discrimination for agiven tolerable size ofantenna system. This advantage ofimproved angular separation with increased frequency is somewhat offset byatendency toward increased size and weight oftrans- mitters needed foragiven range performance.. 
 By the end of WWII Coastal Command had under its control six squadrons of Leigh Light Liberators, one squadron of VLR (very long-range) Liberators, together with six squadrons of USNLiberators and one Czech squadron of Liberators. There were also four squadrons of Catalinas. The VLR Liberator in particular played a very important role in the Battle of the Atlantic, being able to prosecute the ﬁght against U-boats at ranges beyond the capabilities of other Coastal Command aircraft. 
 These indi- cators are useful only with a stationary orvery slowly rotating antenna. At norm a1rates of scanning, itisnecessary todisplay signals onaPPI insuch away that only moving targets appear onthe scope. This can bedone bythe method ofpulse-to-pulse cancellation illustrated inFig. 
 Better assignments are possible  with more sophisticated processing algorithms. The three types of more sophisticated  algorithms most frequently used are 1. Global Nearest Neighbor (GNN)  Consider the whole matrix of statistical dis - tances simultaneously, and minimize a metric such as the sum of all statistical  distances for a complete assignment solution. 
 A fine  graticule can be placed over the end of the CRT screen  so that these essential figures can be read at once.  A kindred display is the Type C, where again the  aerial is rocked mechanically, and the spot moved in step,  so that a rough map is drawn. This time it is an eleva-  tion-azimuth display, and the form is what is known as  helical scanning. 
 THE 
 112. D. M. 
 Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 11.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 power output and provides radar coverage to 80 nmi and to an altitude of 23,000 ft with  an 80% probability of detection for a 2 m2 target; with azimuth and range resolution to  2.25° and 0.25 nmi, respectively. The receiver-exciter efficiently utilizes the transmit - ter solid-state devices with a high duty-cycle waveform. 
 Average velocity during the mission was 0.7 ft/s. The rendezvous radar provides the tracking function for a guidance system. The rendezvous phase of the mission begins after the radar acquires the target. 
 FERENCE SIGNALS 4HE LONGER PATHS FROM THE ANTENNA OUTPUTS TO THE COMPARATOR CIR 
 Because of the noisy nature of the clutter signal, the need to have the control system  bridge regions of weak clutter return, and the requirement not to respond to the dop - pler shift of a true target, the control system usually tracks the azimuth variation of  a specific radar range interval. The maximum range of this interval is chosen so that  clutter will be the dominant signal within the interval. The minimum range is chosen  to exclude signals whose average frequency differs substantially from the frequency  in the region of interest. 
 ducer. Amplitude shaping can be controlled by varying the overlap of the electrodes, as in  Fig. 11.18. 
 D. H. Hoekman et al., “Land cover type and biomass classification using AirSAR data for evalu - ation of monitoring scenarios in the Columbian Amazon,” IEEE Trans. 
 6 
 A medium-wave broad-  cast receiver has tuning coils of normal dimensions,  with probably a hundred turns of wire on a former an  inch or so in diameter. In a short-wave set the tuning  H  . 114 HOW RADAR WORKS  coils may have only a dozen turns of wire. 
 ( a) Proﬁle in the azimuth-elevation plane after elevation processing; ( b) contour plots of the impulse response function (IRF) with the proposed method; (c) comparison of azimuth proﬁles using the proposed method (red) and the classical 2D focusing algorithm with a rectangular window (blue); ( d) as for ( c) but with a Taylor window (blue). T able 2. Imaging quality indicators for a single point target along azimuth. 
 Integration maybeaccomplished intheradarreceiver eitherbeforetheseconddetector (intheIF)oraftcrtheseconddetector (inthevideo).Adefinite distinction mustbemade hetween thesetwocases.Integration beforethedetector iscalledpredetection, orcoherent, integration, whileintegration afterthedetector iscalledpostdetection, ornoncoherent, integra­ tion.Predetection integration requires thatthephaseoftheechosignalbepreserved iffull benefitistobeobtained fromthesumming process.Ontheotherhand,phaseinformation is destroyed bytheseconddetector; hencepostdetection integration isnotconcerned with preserving RFphase.Forthisconvenience, postdetection integration isnotasefficient as predetection integration. If11pulses,allofthesamesignal-to-noise ratio,wereintegrated byanidealpredetection integrator, theresultant, orintegrated, signal-to-noise (power) ratiowouldbeexactlyntimes thatofasinglepulse.Ifthesame 11pulseswereintegrated byanidealpostdetection device,the resultant signal-to-noise ratiowouldbelessthanntimesthatofasinglepulse.Thislossin integration efficiency iscausedbythenonlinear actionoftheseconddetector, whichconverts someofthesignalenergytonoiseenergyintherectification process.. 30 INTRODUCTION TO RADAR SYSTEMS  The comparison of predetection and postdetection integration may be briefly sumrnari~cd  by stating that although postdetection integration is not as efficient as predetection integr-a-  tion, it is easier to implement in most applications. 
 568 INTRODUCTION TO RADAR SYSTEMS  43. McAulay, R. J.: Interferometer Design for Elevation Angle Estimation, IEEE Tram., vol. 
  AIR SURVEILLANCE RADAR AT 3 BAND WAS DEVELOPED BY .ORTHROP 'RUMMAN THEN 7ESTINGHOUSE  FOR USE AT MAJOR AIRPORTS TO CONTROL LOCAL AIR TRAFFIC  )T WAS AN EXCELLENT RADAR THAT USED A . £ä°Ón  2!$!2 (!.$"//+  WELL 
 "%!- /2 /04)#!,,9   $%&).% '!4% 0!44%2.   '!4% 2%#%33  !.$ '!4% -%4!, $%0/3)4)/. 
 The target-reflected illu- mination is received in the missile, but instead of being processed on board it is retransmitted to the illuminating radar. Here the complex waveform is processed, guidance information extracted, and steering commands transmitted to the mis- sile as in a command guidance system. Multimode Systems.2'4'16 The early CW semiactive systems were generally designed to home all the way from launch to intercept. 
 The pilot can tell by quite a number of other  means where he is over the airfield; all he needs to know  for a safe landing is how high he is at any moment.  Height and the more ready appreciation of a number  of other operational points compel us to use in practice  more complex radar tube pictures than the simple  Type A, but if we have grasped the idea well so far we  need not hesitate to consider some of.the more advanced  displays.  . 
 The capability of this device depends on the quality of the medium used as the delay line. The  delay line must introduce a time delay equal to the pulse repetition interval. For typical  ground-based air-surveillance radars this might be several milliseconds. 
 Although it is easy for mod - ern systems to perform this correlation digitally, the difficulties in having an antenna  rotating at this speed (mainly now a cost issue) have prevented this from becoming  established practice. However, more recent work in Canada has resurrected this idea  for detecting floating ice hazards, where antenna rotation rates of 500 rpm and PRFs  of 12 KHz have been proposed.7 Terma A/S, a Danish company involved in supplying  high performance marine radars, mainly in the noncommercial market, produces the  ScanterTM radar, which has an option that simultaneously transmits on two frequen - cies from a squinting slotted waveguide array. This produces two beams separated by  a few degrees in azimuth. 
 vol.39. pp.ROR7.June27.1966. 34.Mavroides. 
 Frequently these must bedesigned toreject aparticular frequency being radiated byanear-by antenna. Conversely, itisoften necessary tofilter the r-foutput ofthe relay transmitter in order tominimize theradiation ofharmonics that interfere with near-by receivers. The specific filters required foragiven installation must be designed tomeet theoperational requirements ofaspecific system involv- ing agiven complement ofradar, communication, and navigational equipment. 
 IN GROUND 
   ")34!4)# 2!$!2   ÓÎ°ÓÇ PSEUDO 
 lo  ~~.::.:>~  fo ± l,i  (1)  <I)  C  0 a.  <I)  (1)  0:: fa CW  H------1 transmitter  fo±0 fr: fo  Detector  (mixer)  (al  Frequency  ( b) Beot-frequency  amplifier Indicator  Fiaure 3.2 (a) Simple CW radar block diagram; (b) response characteristic of hcat-fmiucncy amplifier. CW AND FREQUENCY-MODULATED RADAR 71  The purpose of the doppler amplifier is to eliminate echoes from stationary targets and to  amplify the doppler echo signal to a level where it can operate an indicating device. 
 Thus, with the use of a computer  simulation to determine the proportionality constant, the limitation on I due to stag - gering is approximately  In≈−   202 5 1log. γdB (2.37) which is plotted in Figure 2.23. These curves, which apply to all multiple-delay cancelers, give answers that are  fairly close to the actual limitation that will be experienced for most practical stagger  ratios. 
 ARRAY MANIFOLD WITHOUT HAVING ANY CONNECTION TO THE 42 MODULE ITSELF&)'52%   3"8OVER  FT TALL AND DISPLACING MORE THAN   TONS  #OURTESY OF 2AYTHEON #OMPANY  . £Î°Çä  2!$!2 (!.$"//+  , 
 DELAY CANCELER AND   A NONSCANNING ANTENNA !NDREWS USED THE PROCEDURE TO MINIMIZE THE RESIDUE POWER  OVER THE FULL ANTENNA PATTERN  WHICH INCLUDES THE MAIN 
 IEEE , vol. 53, pp. 929–936, August 1965. 
 R. Graf: Frequency-Agility Processing to Reduce Radar Glint Pointing Error,  IEE E Trans., vol. AES- 10, pp. 
 W. Bogle: Directional Sea Spec- trum Determination Using HF Doppler Radar Techniques, IEEE Trans., vol. AP-25, pp. 
 Because the velocity oflight ishigh, the intervals oftime that must bemeasured inradar are short. Numerically, the range corre- sponding toagiven delay time is164 ydforeach microsecond elapsing between thetransmission ofthepulse and thereception oftheecho. If itisdesired tomeasure range toaprecision of5yd,which isnecessary in some applications ofradar, time intervals must bemeasured with a precision better than &psec. 
 12. Shroeder, K. G.: Beam Patterns for Phase Monopulse Arrays, Microwaves, pp. 
 LOOKING OCEAN SURFACE IS REPRESENTED AS THE &OURIER SUM OF AN INFINITE NUMBER OF SINUSOIDAL WAVE TRAINS  EACH WITH ITS  CHARACTERISTIC WAVE 
 BAND SIDE 
 Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 19.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 will also suppress weather echo power that may exist in the same velocity region and  bias all the estimates of reflectivity, velocity, and width. Spectral domain clutter filters implemented by a discrete Fourier transform (DFT),  on the other hand, suppress the near zero clutter components in the frequency domain  and may interpolate the remaining spectrum across this region to retain most of the  underlying (signal or noise) spectral information. 
 Curve bapplies toanatmosphere which isone fifthoxygen, atatotal pressure of76cm Hg. due toindependent causes, such aswater vapor and oxygen, aredirectly additive. Water drops inthe atmosphere can affect the passage ofmicrowave radiation intwo ways. 
 Theshortwavelengths allownarrow beamwidths ofhighdirectivity withphysically smallantennas. Narrow beamwidths areimpor­ tantforhigh-resolution imaging radarandtoavoidmultipath effectswhentracking low­ altitude targets.Theshortwavelengths ofmillimeter wavesarealsousefulwhenexploring scattering objectswhosedimensions arecomparable tothemillimeter wavelengths, suchas insectsandcloudparticles. Theseareexamples ofscatterers whoseradarcrosssections are greateratmillimeter wavelengths thanatmicrowaves sincetheyaregenerally intheresonance region(Fig.2.9)atmillimeter wavelengths, butintheRayleigh regionatmicrowaves (where thecrosssectionvariesasthefourthpowerofthefrequency). 
 Ê  Ê76 
 (Published by Raytheon Co., Lexington, Mass.)  60. Barton, D. K.: Sputnik II as Observed by C-Band Radar, 1959 IRE National Conv. 
 howc~cr, this is. SEC 13.2] CATHODE-RAY TUBESCREENS 479 wasteful ofpower—for example, when asteady deflection istobeadded toahigh-frequency sweep that requires acoiloflowinductance and there- fore low sensitivity. Itisthen worth while tousetwo separate coils ora permanent magnet and asingle coil. 
  #HINA   CONICAL SCAN +U 66  ((!3#!4 -ET/P 
 Teclr. J .. vol. 
 2.1 , is assumed to be from a matched-filter receiver  (Sec. 10.2). A matched filter is one designed to maximize the output peak signal to average  noise (power) ratio. 
 There also have been hybrids  of the klystron and the TWT that have been of interest  for radar applications, and which have interesting characteristics. The crossed-field amplifier , like the magnetron, is a crossed-field tube that employs  a magnetic field orthogonal to the electric field. It is capable of wide bandwidth and  generally is of smaller size and does not require the very high voltages of the linear- beam tube. 
 PLANE DIFFERENCE SIGNAL TO COUPLE TO  ALL FOUR HORNS AND USES THE FULL HEIGHT OF THE FEED 4HE SUM SIGNAL USES ONLY THE CENTER TWO HORNS TO LIMIT ITS  % FIELD IN THE  % 
 BAND ACTIVE PHASED ARRAY RADAR DESIGNED TO MEET ALL HORIZON SEARCH AND FIRE CONTROL REQUIREMENTS FOR THE .AVY -&2 IS DESIGNED TO DETECT LOW 
 INVARIANT PERFORMANCE MEASURE  WHICH IS OBTAINED BY SETTING  ,    OR 2 4   22 AND A     4HE  RESULT IS DEFINED AS AN  EQUIVALENT MONOSTATIC RANGE  OR  BENCHMARK RANGE  AND IS DETAILED  IN 3ECTION  )T IS ALSO USEFUL AS A  SANITY CHECK BECAUSE AT THESE LIMITS  ALL BISTATIC  RADAR EQUATIONS MUST REDUCE TO AN EQUIVALENT MONOSTATIC EQUATION ÓÎ°ÎÊ  -// Ê, ,Ê 
 9, pp. 399–416, 1852. 117. 
 The  notches at dc, at the prf, and the harmonics of the prf are increasingly broad with increasing  number of delay lines. Although added delay lines reduce the clutter, they also reduce the  number of moving targets detected because of the narrowing of the passband. For example, if  the - 10 dB response of the filter characteristic is taken as the threshold for detection and if  the targets are distributed uniformly across the doppler frequency band, 20 percent of all  targets will be rejected by a two-pulse canceler (single delay-line canceler), 38 percent will be  rejected by a three-pulse canceler (double canceler), and 48 percent by a four-pulse canceler  (triple canceler). 
 AES, vol. 40, pp. 38–56, 2004. 
 Howard, D. D.: High Range-Resolution Monopulse Tracking Radar and Applications, EASCON '74  Record, pp. 86-91, IEEE Publication 74 CHO 883-1 AES. 
 9.2 TERMINOLOGY Electronic warfare is defined as a military action involving the use of electromag- netic energy to determine, exploit, reduce, or prevent radar use of the electro- magnetic spectrum.3"6 EW is organized into two major categories: electronic warfare support measures (ESM) and electronic countermeasures (ECM). Basi- cally, the EW community takes as its job the degradation of radar capability. The radar community takes as its job the successful application of radar in spite of what the EW community does; the goal is pursued by means of ECCM tech- niques. 
 11)is encountered forafrequency change of2percent. The beamwidths are 1°inthe vertical dimension and 6°inthe horizontal dimension. The pulse width is2psec, theoutput power 500 kw. 
 Solid-state microwave devices hold great promise for future systems where a solid-state module is associated with each radiating element; improvements in terms of aperture control, reliabil- ity, and efficiency continue. Phased arrays can be controlled adaptively, partic- ularly for sidelobe cancellation. This is an area where theory and understanding have advanced much. 
 If the new detection is adjacent to any detection in the set of adjacent detections, it is added to the set. Two detec- tions are adjacent if two of their three parameters (range, azimuth, and elevation) are the same and the other parameter differs by the resolution element: range cell A/?, azimuth beamwidth 6, or elevation beam width y. A simulation36 was run to compare the resolving capability of three common detection procedures: linear detector with T = (L + Aa, linear detector with T = B(L9 and log detector with T = C + (L. 
 Sensors 2019 ,19, 2605 space is created by performing principle component analysis (PCA) on the difference image and k-means algorithm classiﬁes the projections onto the eigenvector space into two classes: e.g., change and no-change. The basic steps are given in Algorithm 3. It should be noted that, in our framework, PCA was replaced with K-SVD because one can adjust the dictionary size and the sparsity constraint to obtain change maps with different levels of details. 
 SIDED TAILS OF THE GAUSSIAN AND EXPONENTIAL SPECTRA  OUTSIDE  A MULTIPLE   K  OF THE STANDARD DEVIATION OF THE SPECTRA  A ROUGH  BUT CONSERVATIVE   ESTIMATE CAN BE FOUND OF HOW WIDE THE -4) NOTCH MUST BE TO ACHIEVE A REQUIRED IMPROVEMENT FACTOR  ) 3UCH A CURVE IS SHOWN IN &IGURE  BASED ON THE CLUTTER  SPECTRA SHOWN IN &IGURE  !LTHOUGH THIS APPROACH WOULD ONLY BE STRICTLY CORRECT FOR AN IDEAL -4) FILTER WITH A STEP 
 AMBIGUOUS 02&S  FOR EXAMPLE  WHEN TRANSMITTED FROM AN AIRBORNE RADAR %XAMPLES ARE GIVEN IN 7ILLIS .   ")34!4)# 2!$!2   ÓÎ°Ó /THER IMPLEMENTATIONS OF PULSE CHASING ARE POSSIBLE )N ONE CONCEPT  THE FIXED  MULTIBEAM RECEIVE ANTENNA IS USED AND TWO 230S ARE TIME 
 Mem. RM-1008,  December 17, 1952. 15. 
 Hanle, “Pulse chasing with bistatic radar-combined space-time filtering,” in Signal Processing  II: Theories and Applications , H. W. Schussler (ed.), North Holland: Elsevier Science Publishers  B. 
 Some examples were discussed earlier in connection with the behavior of sea clutter at low grazing angles in Fig. 13.13. In fact, the sharp falloff of the nonducting data in Fig. 
 Fried(eds.).JohnWileyandSons.Inc..NewYork.1969. 56.Andreone. V.M..andC.N.Bates:Doppler RadarBoastDesignInnovations, Microwal'es. 
 STC works quite well for unwanted biological returns near the peak  of the radar beam, but when used with a cosecant-squared antenna beam it solves one  problem but creates another: it also decreases sensitivity to desired targets at high  elevation angles where the antenna gain is low. The solution to this problem is to boost  the antenna gain at high elevation angles to be considerably higher than the require - ment for the cosecant-squared pattern. Not only does this compensate for the use of  STC, but also enhances the target-to-clutter signal ratio for targets at high elevation  angles, thus improving MTI performance. 
 PULSE TRANSMIT ENERGY OF  * .ONLINEAR FREQUENCY MODULATION IS USED WITH A PULSE COMPRESSION RATIO OF  TO ACHIEVE RANGE 
 Such  interest in solid state has also been due, in part, to its completely replacing vacuum  tubes in receiver and computer applications. The solid-state transmitter is discussed in  Chapter 11, and a brief comparison of it with the vacuum tube transmitter is given at  the end of this chapter. The chief advantages of a solid-state radar transmitter are that  it can operate with wide bandwidths; it has the potential for long life; and it is favored  by some buyers of radar. 
 &IX RECEIVER CONCEPT REQUIRES THE  USE OF A COHERENT HARD LIMITER THAT PRESERVES THE PHASE OF THE  SIGNAL WHILE KEEPING THE  AMPLITUDE AT A CONSTANT VALUEp 4HE COHERENT LIMITER IS INSERTED UPSTREAM OF THE PULSE  COMPRESSION FILTER IN A RADAR THAT USES PHASE 
 697-708, June, 1964.  23. White, J. 
 (ILL    0 - 7OODWARD   0ROBABILITY AND )NFORMATION 4HEORY WITH !PPLICATION TO 2ADAR   0ERGAMON  0RESS    $ "RANDWOOD  h&OURIER 4RANSFORMS v IN  2ADAR AND 3IGNAL 0ROCESSING   "OSTON !RTECH (OUSE     ' 7 $ELEY  h7AVEFORM DESIGN v IN  2ADAR (ANDBOOK  - ) 3KOLNIK ED   ST %D  .EW 9ORK  -C'RAW 
 The tan(q i) column  shows the factor by which the I and Q values are multiplied for each iteration. Note that  these values are fractional powers of 2, so the multiplication can be realized by shifting  the binary I and Q values right by i places. The q i  column shows the arctangent of this  factor, which can also be thought of as the phase shift applied during each iteration. 
 SCAN SYSTEM BECAUSE OF THE LONG TRANSIENT SETTLING TIME OF THE FILTERS 4HE LIMITATION ON  ) DUE TO INTERNAL 
 1, table 6.2, and in Ref. 5, table 1.  Aperture blocking. 
  %UROPE      #  +U 9ES . 
 Kock, W. E.: Related Experiments with Sound Waves and Electromagnetic Wavcs. /'roc,. 
 PORT OF )N3!2 OBJECTIVES 3PACE 
 Widrow, B.. P. E. 
 WAVE /4( RADARS  EXPLOIT VERTICALLY POLARIZED (& SIGNALS n -(Z  AND THE CONDUCTIVE PROPERTIES OF SEA WATER TO DETECT TARGETS AT RANGES LIMITED TO ABOUT  KM 4HIS UPPER LIMIT GENERALLY APPLIES TO LARGE SHIPS AND FREQUENCIES IN THE LOWER (& BAND   %#- TO /4( 2ADAR  &OR BOTH SKYWAVE AND SURFACE 
 advantages and disadvantages of large surveillance radar in space should also be considered. Target characteristics and requirements for coverage, track data rate, and re- visit rate are important parameters. The radar subclutter visibility capability, an- tenna size, scan rate, and grazing-angle limitations also determine the orbit se- lected for the SBR. 
 Compensation is possible only for echoes from the most recent transmission; echoes from prior transmissions (multiple-time-around clutter) cannot be suppressed by doppler filtering in pulsed oscillator radars, and for this reason alone such radars are no longer popular. Those readers interested in the methods employed to compensate the coho in these older radars are referred to Sec. 5.5 of the 1970 edition of this handbook. 
 Electron density proﬁles for ISR and ionosonde. 5. Conclusions This paper ﬁrst validated the ability of PolSAR as an effective device in measuring the TEC of the ionosphere, and then demonstrated the feasibility of using known TEC to help improve the topside proﬁle of ionosonde. 
 16, pp. 41-42, March, 1973.  45. 
 ABLE  A BINARY INTEGRATOR SHOULD BE USED TO AVOID FALSE ALARMS DUE TO INTERFERENCE 7HEN A MODERATE NUMBER OF PULSES  TO   ARE AVAILABLE  A BINARY INTEGRATOR OR A MOV 
 An example is  shown in Figure 15.6.37 On the other hand, while the totality of the NRL 4FR results  appeared to show saturation for wind speeds above about 20 kt, the high and low-to- moderate wind-speed data were collected at different times in different places under  different conditions of sea-surface development, and discrepancies between the two  data sets for common wind speeds have weakened the evidence for saturation.38  Other investigators deny that it is even possible to express wind dependence in the  form of a power law, proposing the existence of a kind of threshold wind speed,  below which clutter virtually vanishes and above which the clutter level rises rapidly  toward a saturation value.18 This is indicated by the curves in Figure 15.7, where  the straight lines correspond to various power laws and the curved lines derive from FIGURE 15.5  Frequency dependence of sea clutter for wind  speeds of about 15 kt: 5.3 GHz, Feindt;34 13.9 GHz, Schroeder;35  and 34.4 GHz, Masuko31 ch15.indd   12 12/15/07   6:17:00 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter. 
 (3.16) requires fewer bits than that of Eq. (3.15) because its maximum value is 3 dB. The PROM address also is unipolar and may be limited at a ratio where the PROM output drops to zero. 
 9.3; the first strategy to be adopted by radar designers is to try to avoid interception by the opponent electronic devices. Section 9.4 is dedicated entirely to the anal- ysis of the major ECM techniques and strategies. It is important to understand the ECM threat to a radar system in order to be able to efficiently react to it. 
 Another CF AR technique is the hard limiter, sometimes  called the Dicke fix. 12-74 This consists of a broadband IF filter followed by a hard limiter and  a narrow-band matched filter. The hard limiter is set low enough to ensure thjt receiver noise  is limited. 
 Energywastappedfromeachwaveguide attheappropriate pointsbydirectional couplers to formbeamsatvariouselevation angles.Considerable waveguide wasusedinthisdesign.To produce the333independent beams,theBlassheightfinderemployed 30milesofS-band waveguide. Butlerbeam-forming array.Rfi 100Another RFbeam-forming deviceistheparallel network attributed toButler.andindependently discovered byShelton. Thisisalosslessnetwork which utilizes3-dBdirectional couplers. 
 229  Faraday rotator. 296  Fast Fourier Transform. 123  and multiple beams. 
 SCALE WIND SYSTEMS  IMPOSSIBLE TO DUPLICATE UNDER LABORATORY CONDITIONS 4HEREFORE  THE LABORATORY IS USED ALMOST EXCLUSIVELY TO STUDY IN DETAIL HOW AN ELECTROMAGNETIC WAVE INTERACTS WITH SOME RESTRICTED AND WELL 
 .ktthis altitude, since topographical features areof little interest, nothing isshown except other aircraft, towns, airports, airways, frequency channels inusebyTeleran ground stations, and the direction and velocity ofthewind. Toassist thepilot inflying acourse, the compass reading isrepeated onadisk mounted over theface ofthe indicator and ruled with parallel lines showing theheading oftheaircraft. These lines areshown dashed inFig. 
 L., and I. D. Olin: Some Recent Observations of Sea Spikes, Internatiotral Cotfir~~~rc~. 
 3, pp. 157-159, September, 1967.  70. 
 r¤ ¦¥³ µ´   LOGLOG GL SLR R V GS 
 It  gives a display on three PPI tubes, and, although  originally designed to give warning of enemy ships, has  now been harnessed to give warnings of icebergs and of  other craft approaching at night or in bad weather.  One weakness in early systems was a difficulty of  distinguishing between ships and buoys, but experts of  the Admiralty Signal Establishment carried out tests on  board H.M.S. Pollux in the Thames Estuary, using  buoys provided with radar corner reflectors. 
 The filter design process consists of placing the zeros to obtain a filter bank response that conforms to the specified constraints. The example that follows was produced with an interactive computer program with which the zeros could be moved until the desired response was obtained. The assumed filter requirements are as follows: . 
 The echo  signal will be modulated at a frequency equal to the rotation frequency of the beam. The  amplitude of the echo-signal modulation will depend upon the shape of the antenna pattern,  the squint angle, and the angle between the target line of sight and the rotation axis. The phase  of the modulation depends on the angle between the target and the rotation axis. 
 However, by applying L'Hopital's rule (differentiating  tiulnerator and denon~inator separately) it is found that 1 E,I is a rnaxirnum whenever sin 0 =  + rl/l/tl. These rliaxinia all have the same value and are equal to N. The tnaximuni at sin 0 = 0  defiles ttie rl~iii~l heccrll. 
 MTI AND PULSE DOPPLER RADAR 139  employed in the noncoherenl MTI receiver,.else the desired amplitude fluctuations would be  lost. Therefore the IF amplifier must be linear, or if a large dynamic range is required, it can  be logarithmic. A logarithmic gain characteristic not only provides protection from saturation,  but it also tends to make the clutter fluctuations at its output more uniform with variations in  the clutter input amplitude [Sec. 
 "ASED 2ADARS !.403 
 POWER MULTICAV 
  
 530 INTRODUCTION TO RADAR SYSTEMS  same as those of interest to microwave radar and include aircraft, missiles, and ships. In  addition, the long wavelengths characteristic of HF radar also provide distinctive information  regarding the sea, as well as aurora, meteors, and land features. (Although the HF hand is  officially defined as extending from 3 to 30 MHz, for radar usage the lower frequency limit  might lie just above the broadcast band, and the upper limit can extend to 40 MHz or more.)  The ability to see a target at long range by means of ionospheric refraction depends on the  nature of the ionosphere (the density of electron concentration) and the radar frequency, as  well as the normal parameters that enter into the radar range equation. 
 Landing radars used for UC/\ (ground control of approach) and some missile control radars  are of this type.  When the term tracking radar is used in this book. it generally refers to the continuous  tracker, unless otherwise specified. 
 2-10, January 1972. 20. Pierson, W. 
 pp. 180-199. February, 1977. 
 Platform Location, Orientation, and Stabilization. The calculation of target height with a radar on a moving platform, such as a ship, aircraft, or satellite (all of which are subject to uncertainties in location and orientation) is somewhat more complicated. Coordinate conversion of measured target range, azimuth, and elevation is necessary to determine the target height. 
 The additional degrees or freedom available in the design of recursive delay-line filters  olTer a steady-state response that is superior to that or comparable nonrecursive filters. How­ ever the feedback loops in the recursive filter result in a poor transient response. The presence  -1 0  10[  0.5  0 I  0  (l)  "' C  0  5t 1 0 -t . 
 NIENTLY BLOW UP JUST WHEN NEEDED MOST ! CURSORY EXAMINATION OF %QS  AND  WILL SHOW WHY 4HE DENOMINATORS OF BOTH EXPRESSIONS CONTAIN THE DIFFERENCE OF TWO COSINE TERMS  THAT BECOME EQUAL IN TWO DIFFERENT CASES 7HEN THE SCATTERING DIRECTION  E S IS ALIGNED  ALONG THE SHADOW BOUNDARY WHERE  EI  
 POWER NOISE JAMMING THAT MUST PENETRATE THROUGH THE RADAR ANTENNA RECEIVING SIDELOBES AT LONG RANGES  %SCORT JAMMING IS ANOTHER %#-  TACTIC IN WHICH THE JAMMING PLATFORM ACCOMPANIES THE STRIKE VEHICLES AND JAMS RADARS TO PROTECT THE STRIKE VEHICLES -UTUAL 
 3.1 General configuration of a radar receiver. receiver discussed here serves only to provide the individual pulse signals in proper form for such doppler filtering. Section 3.12 will discuss data distortions in the synchronous detector or analog-to-digital (A/D) converter which affect these doppler filters. 
 A threshold voltage V7/t/tr/2 = 2.5 is shown. The crosshatched  area to the right or V7/t/tA12 under the curve for signal-plus-noise represents the probability of  detection. while the double-crosshatched area under the curve for noise alone represents the  probability of a false alarm. 
 75.Hayes,R.D.,f.H.Dyer.andN.C.Currie: Backscatter fromGround Vegetation atFrequencies Between 10and100GHz.1976IEEEAlltellllas WIdPropagatioll SocietySymposium. Oct.II15. 1976.pp.93·96.IEEECat.no.76CH1121-3AP. 
 The five types of modulation caused by a complex target are discussed next. Amplitude Noise.  Amplitude noise is the change in echo signal amplitude caused  by a complex-shaped target, excluding the effects of changing target range. 
 .. 355 10.7 Pulser Circuits .,..... ...” ............356 10.8 Load Requirements,. 
 Then, an external DEM is used to remove the topographic phase and, consequently, phase unwrapping is carried out for each interferometric pair. For each high coherence point Pin the i-th interferogram, the wrapped interferometric phase can be expressed as [ 31]: Δϕp i=4π λΔdi+Δϕtopo,p i+Δϕres,p i(1) whereλis the radar wavelength (the X band is used in our real data experiment, and the corresponding λ is 3.2 mm); Δdis the line-of-sight cumulative deformation over the time period of the i-th interferogram, indicating the low-pass (LP) component of the total deformation; Δϕtopo,p irepresents the residual topographic phase component, which can be expressed a Δϕtopo,p i=4πBi λRpsinθΔZp,where Bideﬁnes the vertical baseline, θis the incident angle, Rprepresents the distance between the sensor and the target P,andΔZpdeﬁnes the residual elevation, which is an unknown parameter; and Δϕres,p iis the residual phase component, including phase noise, atmospheric delay, and the high-pass (HP) deformation component. Taking the pure linear model as an example, Δdiin Equation (1) can be written as Δdi= vt, (2) 231. 
 PLANE  IS EQUAL 4HIS EXPRESSION IS DECEPTIVELY SIMPLE AND ACCURATELY ACCOUNTS FOR THE FEED 
 11.1 the parallel-fed array of Fig. 8.2, the energy to be radiated is divided between the  elements by a power splitter. When a series of power splitters are used to create a tree-like  str~lcture, as in Fig. 
 Echo signals received after an interval exceeding the  pulse-repetition period are called 11111/tiple-time-arormd echoes. They can result in erroneous or  confusing range measurements. Consider the three targets labeled A, B, and C in Fig. 
 5.5). With a high tuning rate, the pulse-to-pulse frequency can be made to  appear pseudorandom, especially if the pulse repetition frequency or the tuning rate is varied  rapidly. Many of the advantages of frequency agility can be obtained if the radar frequency  shifts pulse-to-pulse the minimum amount required to decorrelate successive echoes. 
 L. Holloway, “Design of a bistatic dual- doppler radar for retrieving vector winds using one transmitter and a remote low-gain passive  receiver,” invited paper, Proc. of the IEEE , vol. 
 - Ê " - 
 Thisfollowsfromtheproperties oftheFourier transform. Therefore afinitespectrum mustofnecessity betransmitted iftransittimeorrange istobemeasured. Thespectrum ofaCWtransmission canbebroadened bytheapplication ofmodulation, eitheramplitude. 
 Barrett. R. M.: Electronic Scanning: Past and Future, Electronic Scanning Symposium, Apr. 
 ( a) The Doppler rate; ( b) the derivative of the Doppler rate. 57. Sensors 2019 ,19, 213   (a) (b)  Figure 7. 
  -ASTERING THE  /CEANS 4HROUGH 4ECHNOLOGY  0ROC   VOL   /CTOBER n    PP n  $ * -C,AUGHLIN  % "OLTNIEW  9 7U  AND 2 3 2AGHAVAN   h,OW GRAZING ANGLE BISTATIC .#23  OF FORESTED CLUTTER v %LECTRONICS ,ETTERS 
 Correspon d-. Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 93     ingly an object oriented polarization scattering matrix [ So] can be introduced by means of  Equation (11.8b), for which applies:  € S0[]=σ m2         (11.9)  11.4 RCS M easurement Techniques   It is possible to distinguish between the following principle procedures in RCS measurement  techniques:   - Scalar RCS measurements   ⇒  € σ,S  - Complex RCS measurements   ⇒  € σ,S  - Polarimetric RCS mea surements ⇒  € σ[],S[]  These types of modulation have a considerable influence on the measurement system:   - Pulse modulation,   - FM- CW modulation,   - Stepped frequency (CW)   Measurements can be carried out in closed, low -reflective rooms, so -called anechoic cha m- bers, and in open -air.   11.4.1  Measurement of the Scalar Radar Cross -Section σ  RCS measurements have been common since the introduction of Radar technology. 
 It must be of sufficient magni- tude to achieve reliable detection. The clutter statistics generally differ from the statistics of thermal noise but, as a first guess when no other information is avail- able, the required values of SIC might be taken to be those of EIN0. It is signifi- cant that the range dependence enters linearly rather than as the fourth power. 
 2018 ,12, 988–997. [ CrossRef ] 27. Li, J.; Hu, P .; Zhang, Y.; Chen, Z. 
 The normalization condition is equivalent to  the assumption that the energy of the bandpass transmit waveform equals 0.5 J. Matched Filter Time Response.  The matched filter time response to a target  with doppler shift fd can be expressed in terms of the autocorrelation function. 
 Ifany interrogator orradar setofagiven type istobeable tolocate a beacon readily, thebeacon must transmit atsome known frequency and the receiver forthe signals must bereadily tunable tothat precise fre- quent y,whether thebeacon replies arerewived ornot. When thelWa- tion ofthebeacon isunknown (asisusually thecase) and theinterrogator isscanning, itisnot tolerable toincrease the general uncertainty about. 262 RADAR BEACONS [SEC,86 the beacon byhaving tosearch over aband 01frequencies. 
 Thus the amount of power absorbed by the atmosphere is kT, B,(1 - IIL)  and is equal to the noise power AN radiated by the atmosphere itself. From the definition of  effective noise temperature and the fact that l/L is the "gain" (less than unity), the following ,  equation is obtained:  Hence Te = T,(L - 1 ) (12.15)  If the atmospheric loss were 1 dB at a temperature of 260 K, the effective noise tempera-  ture would be 68 K; a 3-dB loss results in Te = 260 K, while a 10-dB loss gives Te = 1340 K.  A plot of the single-polarization bright'ness temperature or space temperature due to both  cosmic noise and atmospheric absorption is shown by the solid curves of Fig. 
 In addition, it seems likely that a slower scanner speed (30 rpm) would Figure 4.33. Detection range versus height for ASV Mks III and VI against a U-class submarine [ 9].Airborne Maritime Surveillance Radar, Volume 1 4-27. have been used on ASV Mk. 
 Note that a diflerent correction must be applied for each range R. When  this correction is applied at each element of the synthetic array, the antenna is said to be  jbcused at a distance R and all the received echo signals from a target at that range are in  phase. The angular resolution when the antenna is focused in the Fresnel region is equivalent  to that in tlic far field. 
 TERM STABILITY FOR A DOPPLER RADAR 2EQUIREMENTS  MEASURE 
 3–7,  February 2006. 176. L. 
 Further, if the specified target RCS is reduced, the dynamic-range requirement for the same desired Pd in- creases as the /Vversus-range curve in Fig. 17.18 shifts to the left. In a PD radar using digital signal processing, the dynamic range is most often limited by the A/D converters. 
 It is usually a collection of capacitors known as a capacitor bank.  The hard-tube modulator permits more flexibility and precision than the line-type modu­ lator. It is readily capable of operating at various pulse widths and various p~lse repetition  frequencies, and it can generate closely spaced pulses. 
 8067, 2003. 19. A. 
     &)'52%  %FFECT OF LIMITING ON ELLIPTIC FILTER RESPONSE                  
 Solid-state transmitters can generate high power at UHF as well as offer the advantages of maintainability and wide bandwidth. L Band (1.0 to 2.0 GHz). This is the preferred frequency band for land- based long-range air surveillance radars, such as the 200-nmi radars used for en route air traffic control [designated ARSR by the U.S. 
 DOMAIN WEIGHTING FILTER IS GENERALLY  REQUIRED FOLLOWING THE MATCHED FILTER TO PROVIDE REDUCED TIME SIDELOBE LEVELS  AT THE  COST OF REDUCED 3.2 AND AN INCREASE IN THE WIDTH OF THE COMPRESSED PULSE !S AN  EXAMPLE  THE USE OF  
 TURBANCE POWER RATIO AND DETECTION PROBABILITY AND RADAR RANGE AND HEIGHT ACCURACY CALCULATION  RADAR RESOLUTION EVALUATIONS EMPLOYING SUITABLE DATA EXTRACTING LOGICS 4HE 273 SUITE CONSISTS OF THE FOLLOWING MAIN MODULES #<#   AND &ORTRAN TO CALCU 
 The radiating  elements rriight also be mounted on the surface of a sphere, or indeed on an object of any  IIII'1'1ITIIUINJ<'A' IYSIITRI'I> ""ASH) ARRAYANII'NNA INRADAR279 .calledtheManllllut. wasJOO·ftwiJeand36fthighandscanned a100beamovera1200sector. Amajoradvance inphased-array technology wasmadeintheearly1950swiththe replacement ofmcchanically actuated phaseshifters byelectronic phaseshifters. 
 - ! NUMBER OF PHASED ARRAY RADAR SYSTEMS HAVE BEEN BUILT  AND A REPRESENTATIVE SELEC 
 This  procedure results in a conservative prediction of radar range and has the advantage of simpli­ city. The minimum cross section of typical aircraft or missile targets generally occurs at or near  the head-on aspect.  However, to properly account for target cross-section fluctuations, the prohahility­ density function and the correlation properties with time must be known ror the particular  target and type of trajectory. 
 M. Lake, H. Rungaldier, J. 
 Circular polarization canbeselectedtoreduceweather clutter.MTJandthelog-CFAR. OTHER RADAR TOPICS 541  receivers also reduce weather clutter at the radar output. However, in air-traffic-control opera-  tions, it is important that tlle coritroller kriow the locations of tlie bad weather so as not to  vector aircraft througll it. 
 OF 
 D. Hoffmeyer, and J. O. 
 The Kalman filter can, in principle, utilize a wide  variety of models for measurement noise and trajectory disturbance; however, it is often  assumed that these are described by white noise with zero mean.75 A maneuvering target does  not always fit such an ideal model, since it is quite likely to produce correlated observations.  The proper inclusion of realistic dynamical models increases the complexity of the calcula­ tions. Also, it is difficult to describe a priori the precise nature of the trajectory disturbances. 
 TIAL ISOLATION WITH SPATIAL ANDOR SPECTRAL CANCELLATION TO REDUCE THE TRANSMITTERS DIRECT 
 This may be verified by comparing the nose-on values in the two figures. At this angle the entire ring of the base of the cone is excited, but as the aspect angle swings away from nose- ANGLE FIG. 11.9 Measured RCS of a 15° half-angle cone (horizontal polarization). 
 11–19. 188. G. 
 DOPPLER MAP FOR A #0)  SIMILAR TO THAT  SHOWN IN &IGURE  3EVERAL #0)S WITH THE SAME 02&  BUT POSSIBLY DIFFERENT TRANSMIT CARRIER FREQUEN 
 BASED TRAPPING LAYER DOES NOT HAVE THIS SKIP ZONE PHENOMENON (EIGHT 
 This tube delivers a peak power of 100 kW  with a 0.005 duty cycle at a frequency between  34,512 and 35.208 GHz. The efficiency is  about 25 percent. ( Courtesy Varian Associ- ates, Inc., Beverly, MA.) . 
 A degradation in the noise figure of a predetermined amount usually is co9sidered as the  criterion for diode failure when defining burnout. Sometimes an increase in noise figure of  3 dB has been used as the criterion. 19 In other cases, a 1-d B increase has been used.15  However, with Schottky and point·contact diodes, there is an increase in 1/f noise and a  decrease in the breakdown voltage at lower power levels than would be indicated by the above  criteria. 
 Geosci. Remote Sens. 2007 ,45, 1115–1122. 
 AGED RADAR RETURNS       
 A PPI has a rotating vector with the radar at th e origin, which  indicates the pointing direction of the antenna and hence the bearing of targets. It shows a map -like  picture of the area covered by the radar beam.   Signal Timing   Most functions of a radar set are time -dependent. 
 JAM ¾,EADINGTRAILING EDGE TRACK ¾.ARROWBAND DOPPLER NOISE DETECTOR ¾ ¾6ELOCITY GUARD GATES ¾ ¾ 3IGNAL  PROCESSING RELATED6'0/ RESET ¾ ¾ 3IGNAL REALISM ¾ ¾ ¾!CCELERATION LIMITING ¾ ¾ ¾#ENSORED OR ORDERED STATISTIC #&!2 ¾ ¾$OPPLERRANGE RATE COMPARISON ¾ ¾4IME AVERAGE #&!2 ¾4OTAL ENERGY TEST ¾. Ó{°£ä  2!$!2 (!.$"//+  Ó{°ÈÊ  / 
 Deformation modeling has a signiﬁcant impact on the subsequent processing steps, including high coherence point identiﬁcation, unknown parameter estimation, and phase unwrapping. It can also provide a reference for the interpretation of the ﬁnal deformation results. Among traditional time-series models, the most commonly used is the linear velocity model, which simply assumes that temporal displacement follows linearly varying characteristics, and treats the deformation rate as a constant parameter over each time-adjacent interferometric period. 
 It has much lower power than a  gyroklystron (discussed later) at this frequency, but its 18 cm by 10 cm (diameter) size  is considerably smaller and it costs considerably less than a gyroklystron. A similar EIK, also built by CPI, has been used in the NASA CloudSat spaceborne  radar that provides the vertical profile of clouds for understanding cloud effects on  both the weather and climate.20 It operates at a center frequency of 94 GHz with a  250 MHz bandwidth, 1.5 kW peak power, 3.3 µs pulse duration, 4300 Hz prf, and an  efficiency of 32%. It is conduction cooled. 
 This linearly frequency-modulated signal is then fed into mixer 1, instead of the LO signal, for the case of pulse compression. Waveforms other than linear frequency modulation may be used for pulse compression. In Fig. 
 ", !Z !Z $OP A 3    WHERE A  IS THE AZIMUTH BEAMWIDTH   2 IS SLANT RANGE   ., IS THE NUMBER OF LOOKS HERE  ASSUMED TO BE TAKEN IN THE AZIMUTH DOMAIN   AND  4!Z "$OP  IS THE AZIMUTH TIME 
 D. Prichard, The Radar War: The German Achievement , 1904–1945 , Cambridge, UK: Patrick  Stephens Ltd., 1989. 54. 
 NRL Report 7533, Naval Researclz Laboratory, Washington, D.C., Mar. 27, 1973.  31. 
 PERFORMANCE RADAR 4HERE WAS  AT ONE TIME  A SINGLE 
 *  CW  transmitter (24 k rb  ' Detector  (mixer) 6 = Beat-frequency  amplifier Indicator  70INTRODUCTION TORADAR SYSTEMS important earlyapplications oftheCWradarprinciple weretheproximity (VT)fULeandthe FM-CW altimeter. TheCWproximity fuzewasfirstemployed inartilkry projectiles during WorldWarIIandgreatlyenhanced theeffectiveness ofbothfieldandantiaircraft artillery. Thefirstpractical modeloftheFM-CW altimeter wasdeveloped bytheWeskrn Electric Company in1938,although theprinciple ofaltitude determination usingradio-wave reflections wasknowntenyearsearlier,in1928.1 TheCWradarisofinterestnotonlybecauseofitsmanyapplications. 
 CALLED APERTURE GAIN ' AP   '! AP  P L           &)'52%  0ARABOLIC REFLECTOR IN X 
 Alldata voltages and power voltages fortheindicators aresupplied from acentral. point, the so-called ‘(power console, ”which houses the antenna rotation controls, the transmitter switches, aservo-driven. SEC. 
 C.: "Physics in Meteorology," Sir Isaac Pitman & Sons, Ltd., London, 1957. 34. Saxton, J. 
 But the  needs of radar, which compel us to use very high fre-  quencies, have caused investigation to be made into the  attenuation limits at extremely high frequencies, and  thus it is that for most radar systems we use very short  wavelengths, handled by aerial systems which at first  appear to follow optical laws more than the normal  practice of electromagnetic-wave propagation.  When Watson-Watt first conceived a practical radar  system the ‘floodlight’ system was devised. In this a  high-power transmitter kicked a series of pulses out into  space in every direction. 
        
 The other limit is determined by the far field of the synthetic  apaturc:; i.e., by the need to restrict the aperture size so that the phase front can be considered  as a plane wave. When this condition applies, the SAR is called unfocused. Figure 14.2 defines  the maximum aperture of an unfocused SAR s,t.:h that the difference between the minimum  and maximum (two-way) paths is a quarter wavekngtl; From this geometry it can be derived  that the eITective length Le of the synthesized antenna h jRJ.., so that the cross-range resolu­ tion for the unfocused synthetic antenna is  '5cr = jRJ../2 (14.5)  Figure 14.2 Geometry of the unfocused SAR. 
 The accuracy isdetermined entirely bytheprecision ofthescanning PPI and bythe geometrical relationship between the PPI and the map. Slight changes inparallax between the center and the edge ofthetube can be compensated byusing asuitably nonlinear range sweep. Ifthe radar site ismoving, acompensating motion must beapplied tothe map inorder tomaintain the proper relationship onthe final displays. 
 Werner, “The SIR-C/X-SAR synthetic aperture radar  system,” Proceedings of the IEEE , vol. 79, pp. 827–838, 1991. 
 Figure 2.80 b shows a  sketch of this effect. To ensure that the noise-like pulse-compression sidelobes will not exceed the system  noise after the MTI canceler, the system stability budget must ensure that the instability  sidelobe level is lower than the dynamic range of the receiving system. The receiving  system dynamic range is ultimately determined (in a well-designed system) by the IF  †  All signal processing following the A/D detector is done digitally. 
 Therefore, when the external load is constant, the stress can be considered a constant, and the higher the elastic modulus is, the lower the deformation performs. The physical parameter viscosity (also known as the viscosity coe ﬃcient) is a measure to describe the viscosity of a ﬂuid, which is a demonstration of the ﬂuid ﬂow dynamics for its internal friction phenomenon [ 38]. Higher viscosity reﬂects greater friction in ﬂuid. 
 inwhichthedielectric ofaferroelectric material isafunction oftheapplied electric field.arealsopossihle.49TheyseembettersuitedforVHFandUHFthanforhigherfrequencies. Electromechanical phase-shifting delices. Inaddition toelectronic phaseshifters, electrome­ chanical devicesforchanging phasehavebeenusedinphased-array radars,especially inthc earlymodels. 
 7.5, McGraw-Hill Book Company, New York, 1950.  32. Middleton, D.: Statistical Theory of Signal Detection, IRE Trans., no. 
 BASED  OR GROUND 
 Previously, a variety of limiting or logarithmic  receiver approaches were used to perform various signal-processing functions. These  receivers must define an allowable error in their outputs relative to their ideal nonlin - ear response. Receivers that include some form of gain control must distinguish between instan - taneous dynamic range and the total dynamic range that is achieved as a result of  programmed gain variation. 
 Ifthe echopulse-train didcontainadditional modulation components, caused,forexample, bya fluctuating targetcrosssection, thetracking accuracy mightbedegraded, especially ifthe frequency components ofthefluctuations wereatorneartheconical-scan frequency orthe sequential-Iobing rate.Theeffectofthefluctuating echocanbesufficiently seriousinsome applications toseverely limittheaccuracy ofthosetracking radarswhichrequiremanypulses tobeprocessed inextracting theerrorsignal. Pulse-to-pulse amplitude fluctuations oftheechosignalhavenoeffectontdcking accur­ acyiftheangularmeasurement ismadeonthebasisofonepulseratherth"anmany.Thereare severalmethods bywhichangle-error information mightbeobtained withonlyasinglepulse. Morethanoneantenna beamisusedsimultaneously inthesemethods, incontrast tothe conical-scan orlobe-switching tracker, whichutilizesoneantenna beamonatime-shared basis.Theangleofarrivaloftheechosignalmaybedetermined inasingle-pulse systemby measuring therelativephaseortherelativeamplitude oftheechopulsereceived ineachbeam. 
 TRACKING RADAR 181  measured hy tile radar is ohlained artcr correction is made for the <liffcre11ce in atmospheric  refraction ror optical and RF propagation. This type of dynamic calibration requires the radar  to be large enough to track satellites.  There is nothing unique about any of the individual processes that enter into on-axis  tracking. 
 This waveform does not result in ambiguities since there  is only one peak, but the single peak might be too broad to satisfy the requirements of  accuracy and resolution. The peak might be narrowed, but in order to conserve the volume  under its surface. the function rnust be raised elsewhere. 
 Acommon formofradarantenna isareflector withaparabolic shape,fed(illuminated) fromapointsourceatitsfocus.Theparabolic reflector focusestheenergyintoanarrowbeam, justasdoesasearchlight oranautomobile headlamp. Thebeammaybescanned inspaceby mechanical pointing oftheantenna. Phased-array antennas havealsobeenusedforradar.Ina phasedarray.thebeamisscanned byelectronically varyingthephaseofthecurrents across theaperture. 
 Thus,radiation patterns withextremely lowsidelobesorwithashapedmainbeammaybeachieved. Separate monopulse sumand difference patterns, eachwithitsownoptimum shape,arealsopossible. Graceflll degradation. 
 A number of hits are received as the antenna scans by each  target. The detection decision is based on the energy from all the hits received and not just on  the energy received when the center of the beam· illuminates the target. Thus it is not the  maximum directivity which is important, but the total directivity integrated over the number  of hits processed by the radar. 
 Atthistime.thesignalprocessor canbesettoaccommodate thenextdwell.Ifthearray antenna employs nonreciprocal phaseshifters, thecomplementary phasedistribution needed forreceptionissetjustafterthetransmission ofthepulse.Whilethesystemisbeingsetforthe nexttransmission, thedatareceived fromthelasttransmission canbeloadedintobuffer storage fortransfer totheradarcontrolcomputer. Thus,duringtheNthsequence ofdwell executions, thereturnsfromthe(N-l)stsequence areprocessed andcommands aregen­ cratedforthc(N+I)stsequence. Timcandradarpower(orenergy)aretworesources thatmustbeproperly handled ina. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.436x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 these networks are expensive and lossy and contain errors. An alternative is to use a  broadband beam-switching technique such as the equal-line-length Blass matrix84 or a  Rotman lens.83 For 2D scanning these techniques become quite complex. 
 21. Bean. B. 
 RADIATION FROM THE EDGE OF THE REFLECTOR THAT CAUSES RADIATION LOBES BEHIND THE REFLECTOR &OR A CENTER 
 It is also possible to use the amplitude fluctuations to recognize the doppler component  produced by a moving target. MTI radar which uses amplitude instead of phase fluctuations is  called noncoherent (Fig. 4.33). 
 This is accomplished in the radar  system diagramed in Fig. 4.5 by generating the transmitted signal from the coho reference  signal. The function of the stalo is to provide the necessary frequency translation from the IF  lo the transmitted (RF) frequency. 
 The output signal-to-noise ratio thus  ohtained may be substituted into Eq. (2.6) to find the minimum detectable signal, which, in  turn. is used in the radar equation, as in Eq. 
 (23.13) will have di- mensions of m6/m3. Conversion to the more commonly used units of mm6/m3 re- quires that the result be multiplied by the factor 1018. Because Z values of interest can range over several orders of magnitude, a logarithmic scale is often used, where dBZ = 10 log Z (23.14) Equation (23.13) can be used to measure the reflectivity factor Z when the an- tenna beam is filled, when the Rayleigh approximation is valid, and when the scatterers are in either the ice or the water phase. 
 45. R. F. 
 At low angles where the ranges are long, a low prf is used. At the higher angles  where the ranges are short, a high prf can be used. If an increase in complexity can be tolerated,  a number of multiple elevation beams can be scanned simultaneously to increase the data rate,  unambiguous range, and/or number of pulses per beam position. 
 But it  would equally be possible to earth the valve anodes.  Then the body would experience no shock on touching  them, but all other negative parts would produce a  sensation of shock, because they would be 150 volts  “below earth,’ as we say in radar parlance. A layman  usually thinks of the risk of getting a shock off only a  ‘positive’ voltage, but, as the body is usually at earth  potential, with the feet standing on the ground, what  really matters is the voltage with respect to earth. 
 J.: A Simplified Calculation for Dolph·TschcbyschdT Arrays, J. Appl. Phys., vol. 
 The beam of an antenna points in a direction that is normal to the phase front. In phased arrays, this phase front is adjusted to steer the beam by individual control of the phase of excitation of each radiating element. This is indicated in Fig. 
 AP-17, pp. 308-314, May, 1969  52. Kennaugh, E. 
 This is an important reason for its use for UHF-TV with its time-varying-amplitude  waveform. It also should be an advantage for radar applications that require shaped  waveforms at frequencies up to 1000 MHz, when it is required to reduce the far-out  spectral energy. A CEA, such as manufactured by L-3 Communications, can operate within the  UHF-TV band from 470 to 806 MHz with an 8 MHz bandwidth (the spectral width  of a TV channel), 130 kW peak power at 60% efficiency, and an average power of  6 kW or greater. 
 3, pp. 827–834, March 2002. 32. 
 SORS IN GENERAL  INCLUDING THE ANTENNA  0LATFORM IS A GENERIC TERM REFERRING TO THE  VEHICLE WHERE THE RADAR AND ANTENNA ARE INSTALLED 4YPICAL RADAR PLATFORMS INCLUDE PEDESTAL FIXED SITE   GROUND VEHICLES  SHIPS  AIRPLANES  5!6S  AND SPACECRAFTSATELLITES 4HE FOLLOWING SHORT SECTION IS DEVOTED TO PLATFORM IMPACTS AND SOME KEY ASSOCIATED DESIGN DRIVERS 4HESE INCLUDE MASS  VOLUME STOWAGEDEPLOYMENT   GIMBALS PRECISION MECHANICAL POSITIONING SYSTEMS   MATERIALS  AND MECHANICAL TOLERANCES &INALLY  THERE IS A BRIEF DISCUSSION OF ENVIRONMENTAL DESIGN CONSIDERATIONS AND RADOMES  XY Z 
 Therefore  I'liis applies to the voltage spcctrum. Since the standard deviation of the power spcctrum is  less than that of the voltage spectrum by fi, tile power spectrum due to antenna scanning can  be described by a standard deviation  %, number of hits within 3 dB beamwidth  Figure 4.31 Limitation to improvement factor due to a scanning antenna. Antenna pattern assumed to be  of gaussian shape. 
 One other method should be mentioned of achieving coherent MTI. If the number of  cycles of the doppler frequency shift contained within the duration of a single pulse is  sufficient, the returned echoes from moving targets may be separated from clutter by suitable  RF or IF filters. This is possible if the doppler frequency shift is at least comparable with or  greater than the spectral width of the transmitted signal. 
 396-401, IEEE Publication 75 CHO 938-1 AES.  64. Clark, B. 
 105, pp. 178-183.  73. 
 APERTURE 
 ENTRY  &IELD TESTS SHOWED THAT --3 RANGE DATA COMBINED WITH  42!$%8S MONOSTATIC  RANGE DATA IN A TRILATERATION NET PROVIDED THE MOST ACCURATE ESTIMATE OF EXO 
 I{. R.: Pcrft~rriiance Measures arid Optimization Condition for a Third-Order Sampled-  Ihta Tsnckcr. /EKE Trtrrr.r.. 
 Rl. Kaurman. I.: The Band Retween Microwave and Infrared Regions. 
 DIRECTIONALCOUPLERS . phase shifters, as shown in Fig. 7'.Ib, providing an incremental delay from ele- ment to element of t = (sic) sin 60, where c = velocity of propagation. 
 ' ARE HIGH EFFICIENCY SWITCHING AMPLIFIER CONFIGURATIONS THAT REQUIRE SPECIALIZED TERMINATION OF THE SIGNAL HARMONICS FILTERING  IN ORDER TO MAXIMIZE THE AMPLIFIER EFFICIENCY 4HESE CAN BE COMPLICATED HARDWARE IMPLEMENTATIONS BUT MAY BE WARRANTED WHERE INCREMENTAL IMPROVEMENT IN EFFICIENCY BRINGS BENEFIT TO THE TRANSMITTER SYSTEM 3ILICON "*4S THAT OPERATE IN THE (& THROUGH 3 
 Remote Sens. 1994 ,32, 786–799. [ CrossRef ] 17. 
 DIMENSIONAL COVARIANCE MATRIX OF THE OVERALL DISTURBANCE  NOISE AND JAMMER   6 RECEIVED BY THE ARRAY  AND  3 IS THE . 
 G.: Continuous Whole Earth Coverage by Circular Orbit Satellite Patterns, R. Aircr. Estab. 
 Themeasurement ofangular position isthemeasurement oftheangleof arrivaloftheequiphase wavefront oftheechosignal.Thetheoretical rmserroroftheangle measurement maybederived inamanner similartothederivations oftime(range)and frequency errorsdiscussed above.Theanalogy between theangularerrorandthetime-delay orfrequency errorcomesaboutbecause theFourier transform describes therelationship between theradiation patternandtheaperture distribution ofanantenna inamannersimilar totherelationship between thetimewaveform anditsfrequency spectrum. Forsimplicity theangularerrorinonecoordinate planeonlywillbeconsidered. The analysiscanbeextended toincludeangularerrorsinbothplanes,ifdesired.Itisassumed that thesignal-to-noise ratiosarelargeandthatthenoisecanbedescribed bythegaussian probability-density function. 
 PERTURBATION MODEL 4HE IDEA COMES FROM THE CONCEPT ILLUSTRATED IN &IGURE B  ! SINGLE SINUSOIDAL COMPONENT OF A COMPLEX SURFACE IS SHOWN WITH AN INCOMING  RADAR WAVE AT ANGLE OF INCIDENCE  P 4HE RADAR WAVELENGTH IS  K  AND THE SURFACE 
 3TATE 4RANSMITTERS   .ORWOOD  -! !RTECH  (OUSE    . 
 Dissipated power: The thermal conductivity of GaAs is poor. The dissi- pated power from larger devices will result in extremely high channel tempera- tures on the die surface, and reliability will be impacted. Silicon Power FETs. 
 VARYING WEIGHTS IN THE CANCELER FORWARD PATHS INSTEAD OF BINOMIAL WEIGHTS 4HE USE OF TIME 
 It is now desperately  essential that he remains a peaceful civilian.  . APPENDIX  NOTES ON THE PLATES  Plate I (frontispiece). 
 In particular, the azimuth taper of the primary beam can be included, FIG. 6.12 Three-dimensional shaped-reflector design. and the section of the reflector aimed at elevation 6 can be focused in azimuth and have a proper outline when viewed from elevation 6 (Fig. 
 The shoulders on the  response with peaks at -32 to - 33 dB would hardly affect any real aspect of Radar perfor m- ance.  . Radar System Engineering  Chapter 11 – Selected Areas in Radar Signal Processing  128          Figure 12.21  Spectrum of non -linear chirp using circle -φ function with response of 5 -pole  Bessel filter with B3=0.7  MHz (dotted line). 
 ING OPERATE WITH HIGH EFFICIENCY HAVE WIDE BANDWIDTH AND BE EASILY TUNABLE BE READILY MODULATED IN AMPLITUDE  FREQUENCY  OR PHASE AS NECESSARY HAVE HIGH RELIABILITY AND LONG LIFE REQUIRE MINIMUM MAINTENANCE HAVE NO DANGEROUS 8 
 607-615, September, 197b.  68. Volts. 
 429-441, 1946.  5. Woodward, P. 
 occurswhendll/dlzisgreaterthan-1.57x10-7m-I.Theradarrangeswithductedpropaga­ tionaregreatlyextended. Holescanalsoappearinthecoverage.Iftheatmospheric indexof refraction weretoincrease. ratherthandecrease. 
 F,  August 1980. 32. H. 
  D"  MEANS  THAT THE PEAK OF THE HIGHEST SIDELOBE IS  D" BELOW THE PEAK OF THE MAIN BEAM 4HE AVERAGE  OR ROOT 
 Received power, radial veloc- ity, and spectrum width can be calculated and are directly related to meteorological variables. where/and v are related by/ = (2/X)v. The mean velocity is given by the first moment of the spectrum fvS(v)dv v — (23.30) J S(v)dv The second central moment crv2 is given by f (v - v)2S(v)dv 2 J "v TJ S(v)dv (23.31) where av is the velocity width. 
 It accomplishes this by  adjusting the threshold, which in turn affects both the false alarm and the miss probabilities.  The dependence of the two errors upon one another is probably the chief limitation of the  Ideal Observer as a radar detection criterion. MiddletonZ5 states that when the probability of  false alarm is 0.05, the probability of detection is 0.90. 
 This consists ofRinparallel with theimpedance oftheline, Z,orwhat amounts tothesame thing inthis case, inparallel withtheradiation resist ante oftheantenna. That is, RZR,.=~z. (17) What temperature istobeassociated with theresistance Z? Ortoput amore restricted question, under what circumstances can wesay that R and Zare atthe same temperature? Clearly this isthe case ifall surroundings oftheantenna with which theantenna iscapable ofexchang- ingenergy areatthesame temperature TasisR.Letusassume forth. 
 &REQUENCY "ANDS   )%%% 3TD  
 PASS )N3!2 L "ASELINE IS RELATIVELY WELL KNOWN  PROVIDING CONSISTENCY THROUGHOUT SYNTHETIC APERTURE L 3CENE IS SAME FOR BOTH IMAGES SINCE DATA FOR EACH ARE COLLECTED SIMULTANEOUSLY L /N 
 TRAFFIC CONTROL RADARS L !32  !IRPORT 3URVEILLANCE 2ADAR L !232  !IR 2OUTE 3URVEILLANCE 2ADAR L !3$%  !IRPORT 3URFACE $ETECTION %QUIPMENT L 4$72  4ERMINAL $OPPLER 7EATHER 2ADAR 4HE NUMERAL FOLLOWING THE LETTER DESIGNATION INDICATES THE PARTICULAR RADAR MODEL    IN SEQUENCE  7EATHER RADARS DEVELOPED BY THE 5 3 7EATHER 3ERVICE ./!!  EMPLOY THE DES 
 IEEE Pub!. 75 CHO 938-l AES.  22. 
 With a matched resistance at the receiver input, the output power is due to receiver  noise alone. The signal generator power is then applied to the receiver input and adjusted until  the signal-plus-noise power is equal to twice the receiver noise power read with the matched  resistance. The input signal under this condition is sometimes said to be the minimum discern-  ible signal. 
 False-alarm control in receivers without doppler filters is sometimes degraded by  errors of a small fraction of the least significant bit (LSB), so correction is preferably  applied at the analog input to the A/D. DC offsets can be measured using digital pro - cessing of the A/D converter outputs and a correction applied using D/A converters,  as shown in Figure 6.13. DC offset correction can also be performed effectively in the  digital domain, provided that the DC offset at the input of the A/D converter is not so  large that it results in a significant loss of available dynamic range. 
 In practice, however, the echo signal  from a target in motion is almost never constant. Variations in the echo signal may be caused  by meteorological conditions, the lobe structure of the antenna pattern, equipment instabili­ ties, or variations in the target cross section. The cross sections of complex targets (the usual  type of radar target) are quite sensitive to aspect.30•36 Therefore, as the target aspect changes  relative to the radar, variations in the echo signal will result. 
 HOP RANGES  THE NO 
 ON 
 This chart allows identification of  those combinations of input frequencies and bandwidths that are free of strong low- order spurious components. Such charts are most useful in determining optimum IF and  LO frequencies during the initial design phase. Once the frequency plan has been deter - mined, computer analysis of spurious responses is typically used to ensure spurious free  performance over the entire range of LO frequencies and RF and IF bandwidths. 
 The  tracking circuits also eliminate false hit-reports which do not form logical tracks. The output  of the automatic tracker is what is displayed on the scope. Since the MTD processor eliminates  a large amount of the clutter and has a low false-detection rate, its output can be reliably  rcmotcd via narrow bandwidth telephone circuits. 
 TYPE RADARS THUS MAKE VERY INEFFICIENT USE OF THE AVERAGE POWER CAPABILITIES OF MICROWAVE TRANSISTORS 4O REPLACE THE OLD  WELL 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 offset corresponding to the PRF. 
 (IGARSS’88) , Edinburgh,  September 12–16, 1988, pp. 1089–1090. Published by Noordwijk, Netherlands: European  Space Agency, ESTEC, 1988. 
 vol. AP-IJ. rr 175 176. 
 GROUND ECHO  16.496x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Some of the return signals from a resolution cell maintain their polarization charac - teristics over time and space, whereas others have a random polarization. This occurs, as  for sunlight, when the polarization ellipse changes its properties randomly and rapidly  with time or with small differences in angle. When both the persistent and random parts  FIGURE   16. 
   -AY    7 ( 0EAKE AND 34 #OST  h4HE BISTATIC ECHO AREA OF TERRAIN AT  '(Z v IN  )%%% 7%3#/.    3ESSION   PP n   6 7 0IDGEON  h"ISTATIC CROSS SECTION OF THE SEA v  )%%% 4RANS !0 
 , .  The largest isolations are obtained with two antennas-one for transmission, the other for  reception-physically separated from.one another. Isolations of the order of 80 dB or more  are possible with high-gain antennas. 
 These include mass, volume (stowage/deployment), gimbals (precision  mechanical positioning systems), materials, and mechanical tolerances. Finally, there  is a brief discussion of environmental design considerations and radomes.  xy z −180 −90 0 90 180 Theta−30−142183450Magnitude (dB)Maximum = 46.987999  FIGURE 12. 
 5.1~. The difference in amplitude  between the voltages obtained in the two switched positions is a measure of the angular  displacement of the target from the switching axis. The sign of the difference determines tlie  TRACKING RADAR153 aproceuure lIsuallyresultsincertainoperational limitations. 
 46 to 16.52. in ground penetrating radar, 21.10 to 21.11 in meteorological radar, 19.18 for planetary radar, 18.52 Polarization-twist reflector, 12.23 Polyphase codes, 8.19 to 8.24 Power-aperture product, 10.1 Power supply, for AESA, 5.10 Practical detectors, 7.4 to 7.11 Precipitation measurement, 19.26 to 19.28 Precision velocity update, 5.33 to 5.34 Probabilistic data association, 7.39 to 7.40 Probability of detection, in pulse doppler, 4.46 to 4.48 Probability of false alarm, in pulse doppler, 4.44 to 4.46 Propagation, anomalous, 26.6 to 26.13 Propagation factor, 26. 1 Propagation, in free space, 26.13 to 26.15 Propagation loss, 4.40 Propagation modeling, 26.13 to 26.17 Propagation, standard, 26.4 to 26.6 Pseudo coherent radar, 6.20 Pulse chasing in bistatic radar, 23.28 to 23.29 Pulse compression block diagram, 8. 
 Low two-way antenna  sidelobes along with the combination of techniques discussed in Section 4.2, such as  guard channel blanking and postdetection STC, are used to mitigate sidelobe clutter  discrete false alarms. MRWS also uses pulse compression to decrease the amount of sidelobe clutter that  targets must compete with. The lower PRF reduces eclipsing and the amount of clut - ter range-folding. 
 TION FOR THOSE DESIGNING A MODERN SURVEILLANCE RADAR TO DETECT MAN 
 A. Benavoli, and Dr. S. 
 This assumption permits construction of scattered fields by assuming that the current over a rough plane surface has the same magnitude as if the surface were smooth, but with phase perturbations set by the differing distances of individual points from the mean plane. For surfaces assumed to be azimuthally isotropic, the usual approach yields integrals of the form _J_ [e-(2k*h cos 6)2[1 - P(C)]J (2^ cos e)W£ cos3 6 J where p(0 = spatial autocorrelation function of surface heights 0 = angle with vertical (T1 = standard deviation of surface heights k = 2WX J0 = first-order, first-kind Bessel functionROUGH SURFACE WITH TANGENTS RETURN FROM INDIVIDUAL FACETS INCIDENTRAYRADARNORMAL ANGLE OFREFLECTION RERADIATIONPATTERN FACETS REFERENCEPLANE MAXIMUM POSSIBLE CONTRIBUTION(IF FACET IS NORMAL TO INCIDENT RAY) ACTUAL CONTRIBUTION . The autocorrelation function of height with distance is seldom known for ter- rain, although it can be determined on a large scale by analysis of contour maps,41 and it has been found for some areas by careful contouring at close in- tervals and subsequent analysis. 
 Inthefirst method, thesensitivity ofthebeacon receiver isdecreased asthe average number ofreplies increases. Weaker interrogations are thus rejected and thereplies arelimited tostronger interrogate msupto the maximum number tolerable. For navigational beacons, ingeneral, this isnot agood scheme since ittends toeliminate replies tothe more distant interrogators, which are likely tobethe ones most inneed of getting them. 
 The data on the synthetic display must be refreshed at a sufficiently high rate to obtain  a high brightness and lo avoid flicker. When a number of displays are used with the output  of a single radar, a dedicated minicomputer can be used at each display position for the  rdresh of data so as to reduce the data-transfer rate from the radar central processor.  9.6 DVPLEXERS AND RECEIVER PROTECTORS  The duplexer is the device that allows a single antenna to serve both the transmitter and the  receiver. 
 CFAR is important since, without it, clutter can excite the radar display and  obscure the presence of desired targets even if the targets are of greater strength than the  clutter. CFAR prevents obscuration of detectable targets by weaker clutter by maintaining  the clutter output from the receiver at a constant .value well below the saturation level of  the display. This is especially important in track-while-scan, or automatic detection and  tracking (ADT) systehs, where even small increases in background clutter could result in  excessive false alarms that overload the capacity of the tracking computer. 
 At the same time, the quest for better performance with lower sidelobes and wider bandwidth keeps the costs high. The greatest potential for cost reductions is believed to lie in the application of solid-state systems with a transmit/receive module at each element. Phased Array Antennas. 
 SPEED TASKS SUCH AS DETEC 
 ASPECT AND  !LL 
  
 Proc IEEE. vol. 54. 
 This is true because microwave semiconductor devices have much shorter ther- mal time constants than RF tubes (milliseconds rather than seconds). The result is that a microwave transistor that is capable of perhaps 50-W average power can- not handle much more than 100 to 200 W of peak power without overheating dur- ing the pulse. The short pulse lengths and low duty cycles typical of older tube- type radars would thus make very inefficient use of the average power capabilities of microwave transistors. 
 The first experimen-  tal detections of aircraft used this radar principle rather than a monostatic (single-site) pulse  radar because CW equipment was readily available. Successful pulse radar had to await the  development of suitable components, especially high-peak-power tubes, and a better under-  standing of pulse receivers.  The first detection of aircraft using the wave-interference effect was made in June, 1930, by  L. 
 ORDER DIFFERENTIAL EQUATION THAT MAY BE SOLVED AS A BOUNDARY 
 Rainey (ed.),  Blackwell Scientific P~~blicatior~s. Londoii. 1976. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.536x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 to control each bit individually. Other phase shifters use a single toroid and a single  driver.94,95 In this configuration, the phase shifter is latched on a minor hysteresis loop  by only partially magnetizing the ferrite. 
 ! )3!2 EXAMPLE 4! 
 ZERO AVERAGE SURFACE SLOPE IN BOTH THE ALONG 
 Keywords: joint sparse reconstruction; interferometric inverse synthetic aperture radar; compressed sensing; near-ﬁeld 3-D imaging; wide angle 1. Introduction Near-ﬁeld 3-D imaging is a microwave imaging technique that is developed on the basis of two-dimensional (2-D) synthetic aperture imaging. As it has higher spatial resolution capability, and has easy availability for engineering realization, near-ﬁeld 3-D imaging is widely applied in Radar Cross Section (RCS) [ 1], non-destructive testing and evaluation (NDTE) [ 2,3], security check [ 4], concealed weapon detection [ 5–7], through-wall and inner wall imaging [ 8,9], breast cancer detection [ 10,11], etc. 
 Theperiodic trainofpulses,however,.does notsufferthislimitation. Thetime-delay erroris determined bythepulsewidthrasbefore,butthefrequency accuracy isdetermined bythe totalduration ofthepulsetrain.Thusthetime-andfrequency-measurement a<:.curacies may bemadeindependent ofoneanother. Fortheprivilege ofindependently controlling thetimeandfrequency accuracy witha periodic waveform, additional peaksoccurintheambiguity diagram. 
 is tlic rr~otirtlnrirrq rrrrotic. .l'lic ativa~it:~gc of the ti~odulating anode is that it reqi~ires little control  power to rnodulate the beam. 'I'lw power necessary is that required to charge and discharge the  capacitance of the klyst roll guri and its associated circuitry, and this is independent of the pulse  lerlgtli The cutoff characteristics of the modulating anode permit only a few electrons to  e4capc Troll\ the clcctrori gu11 during tile interpulse period when tlie beam is turned off. 
 Also, a gaussian representation is often more convenient to  manipulate mathematically. The gaussian density function has a bell-shaped appearance and  is defined by  1 -(x -x0)2  p(x) = J 2 exp 2 2 2m, a (2.15)  where exp [ ] is the exponential function, and the parameters have been adjusted to satisfy the  normalizing condition of Eq. (2.10). 
 ¯ ¯  \  \ \     QQ QQQQ QQ Q\\DQFORSINGLE 
 The output of the range gates is  stretched in a circuit called the boxcar generator, or sample-and-hold circuit, whose purpose is  to aid in the filtering and detection process by emphasizing the fundamental of the modulation  frequency and eliminating harmonics of the pulse repetition frequency (Sec. 5.3). The clutter­ rejection filter is a bandpass filter whose bandwidth depends upon the extent of the expected  clutter spectrum. 
 16,30. The arrangement isone that might ,be appropriate toasystem employing al-psec pulse width and aninter- mediate frequency of30Me/see. The requirement that theamplitude response show noinversion above thelimit level isonenotordinarily met 1V.A.Oleon, “AMoving Coho Conversion Unit, ”RLReport No.975, Apr. 
 Limitations of puke compression. Pulse compression is not without its disadvantages. It re-  quires a transmitter that can be readily modulated and a receiver with a matched filter more  EXTRACTION OFINFORMATION ANDWAVEFORM DESIGN433 accompanying thepulse-compressionwavefoFffi; Suchsystem.instabilitiesmight becausedby noiseonlocaloscillators, noiseontransmitter powersupplies, transmitter timejitter,and transmitter tubenoise.Thesenoisesidelobes willnotcancelintheMTIsystemand,if sufficiently large,theycanresultinuncancelled residuethatwillappearontheradardisplay. 
 Characteristics of Amplifiers and Mixers Noise Temperature. The most frequently cited figure of merit for a mixer or amplifier is its noise figure. However, the concept of noise temperature has proved more useful. 
 Height-finding radars which measure  Ver11(0' rrdorllOI'r"!fl' --- '"o ~06 9 U ~()~ o '"0~o 2 co rl'()~ u :" O? OJ o'Io102030405060708090 (,rOllnq anqlc,rleq (alPROPAGATION OFRADAR WAVES445 2001-,,--,---,---,-----.--,------,--,----,,---, 3.00(1M/{?"- lAOI-----------------~1\ Horizontal polarization 100MH?! ~160\ \ =.140 :i.120 ~.~-Verti(al polarization ~ .~ 8" g100 u '" ~80 0 '"nO ~ 1"n. 40-k 20_3,000 MIf? IOOMH?a I a102030405060708090 Grazingangle,deg fbI FigureILl(a)Magnitude ofthereflection coefllcient asafunction ofthegrazing angle(forsea­ water) (/1)Phaseofthereflection coefficient asafunction ofthegrazing angle(forseawater). Phaseof thereflected wavelagsthephaseofthe/incident wave.(FromBurrows alldAttwood,S courresy Academic Press.l/le) Forarough,perfectly conducting surface,suchasthesea,Ament 70derivedthereflection coefficient as Poexp[-2k2hZsin2rJ;] wherepo=complex reflection coefficient forasmoothsurface k=2rr/}., ~=wavelength 112=mean-square surfaceheight(meanvalueofIt=0) t/J=grazingangle Experimental datatakenovertheseafitthisexpression well;exceptforlargevaluesofthe roughnessp;rameter [(Itsint/!)IA~Itt/!/A>0.11],wherethetheoryunderestimates theexperi­ mentalobservations,7ton Thereflection ofelectromagnetic wavesfromtheseamaybeseparated intoacoherent and an;lIcolrerellt component. 
 The effect of wind at C band is  like that at X band. At lower frequencies, however, the variation of <1° with wind is less  pronounced.  The energy backscattered from the sea will depend on the direction of the wind relative  to the direction of the radar antenna beam. 
   !.401 
 SIDED TAILS OF SPECTRUM VS MULTIPLE OF STANDARD DEVIATION .   -4) 2!$!2  Ó°£Ç !MPLITUDE #HARACTERISTICS  4O PREDICT THE PERFORMANCE OF AN -4) SYSTEM  THE  POWER OF THE CLUTTER RETURNS WITH WHICH A TARGET MUST COMPETE SHOULD BE KNOWN 4HE  AMPLITUDE OF THE CLUTTER RETURNS DEPENDS ON THE SIZE OF THE RESOLUTION CELL OF THE RADAR  THE FREQUENCY OF THE RADAR  AND THE REFLECTIVITY OF THE CLUTTER 4HE EXPECTED RADAR CROSS SECTION OF CLUTTER CAN BE EXPRESSED AS THE PRODUCT OF A REFLECTIVITY FACTOR AND THE VOLUME OR AREA OF THE RESOLUTION CELL &OR SURFACE CLUTTER  AS VIEWED BY A SURFACE 
 Holloway, “Cross correlations and cross spectra for spaced  antenna wind profilers,” Radio Sci ., vol. 31, pp. 157–180, 1996. 
 approach. Passive processing involves the use of a compression network that is the conjugate of the expansion network and is a matched-filtering approach. Al- though a combination of active and passive techniques may be used in the same radar system, most systems employ the same type for generation and processing; e.g., a passive system uses both passive generation and passive processing. 
 Lobe switching, which has been described inthelast Section, isemployed bytheSCR-268 forangle-error determi- nation; infact, the SCR-268 was the earliest production radar touse this technique. The general appearance ofthesetisshown inFig. 6.34, 1ByE.C.Pollard andL.N.Ridenour.. 
 This is probably a reasonable  approximation to the behavior of real targets, provided the angular extent of the target is not  too large compared with the antenna beamwidth. Since 00 varies inversely with distance for a  fixed target size, the tracking error due to glint also varies inversely with distance.  I\ slightly more complex model than the two-scatterer target considered above is one  consisting or many individual scatterers, each of the same cross section, arranged uniformly  along a line or length L perpendicular to the line of sight from the radar. 
 G.: "Laser Radar Systems and Techniques," Artech House, Inc., Dedharn, Ma, 1979.  570INTRODUCTION TORADAR SYSTEMS 95.Tischer. F.J.:TheGroove Guide.aLow-Loss Wav~guide forMillimeter Waves.IEEETrails.. 
 ”Ifany dimension ofthe target issmaller than awave- length, orifthebackward radiation arises from thesecondary maxima in thediffraction pattern, thecross section will bereferred toasa“diffrac- tion cross section. ”When both types ofbackward scattering arepresent, thespecular cross section isusually much greater. Inconsidering theuse ofabsorbent materials, this distinction must always beborne inmind. 
 DIMENSIONAL WINDS 3INCE  IN PRINCIPLE  TWO INDEPENDENT LOOKS CAN MEASURE ONLY TWO COMPONENTS OF VECTOR AIR MOTION  THE ASSUMPTION OF ATMOSPHERIC MASS CONTINUITY IS INVOKED 4HIS  EQUATION OF  MASS CONTINUITY    6IS USED TO OBTAIN THE THIRD 
 Target returns were d i s p l a y e di nA - s c o p ef o r m a t ,s h o w i n g amplitude versus range over a 10 mile range scale [ 7]. The transmitter wavelength was then increased to 1.5 m in order to increase the power and about 1 kW output was achieved. Separate transmit and receive antennas were used and these were initially simple dipoles. 
 Wavelength =1.25 cm,O.SO beam, altitude 7000 ft.radius 24naut]cal mi, 42°16’N. 71°4S’\V. center ofthe picture, with the Toride railroad bridge appearing asa strong signal just south oftheaircraft. 
 +200V — — )k N 1.5 + 1- 200— LlkJ < 1<< 160k. 2W , ~. P6AC7 :. 
 However, fundamental conceptual problems in applying the Bragg hypothesis in microwave scattering, along with recent questions about the validity of its predictions and the possibility of alter- native scattering hypotheses, have reopened inquiry into the physical origins of sea scatter and how best to model it.9"14 This being the case, speculation about physical models will be kept to a minimum in the sections on the empirical be- havior of sea clutter. The problem of modeling sea scatter will be discussed sep- arately in a later section. 13.2 DESCRIPTION OF THE SEA SURFACE Close observation of the sea surface discloses a variety of features such as wedges, cusps, waves, foam, turbulence, and spray, as well as breaking events of all sizes and masses of falling water. 
 Each time that V,isturned on,thesurge ofcurrent through itsplate circuitz triggers the single-stroke blocking oscillator formed by V5,giving rise tothe desired pulse. Itshould benoted that aslight delay isinherent inthe production ofthe first pulse, since ashort but finite time isrequired toturn onVq.Later pulses arealldisplaced by 1Forexample, inthecaseof1-mile markers thisfrequency is93.12 kc/see. *Thecurrent necessary tocharge C?increases thepositiveness ofthisaction.. 
 ● The mechanical packaging of the power combiner should allow modules to be  repaired easily. The packaging should also provide short, equal phase and low-loss  interconnections between the amplifier modules and the combiner. Power combiners may be either isolative or reactive designs. 
 377–389, April 1964.  4. T. 
 2,for theover-all receiver noise figure. N..,rd, =~(Ni-[ + T’–1)1 where g=gain oftheconverter, T=noise temperature oftheconverter, Ni., = noise figure ofthei-famplifier.(1) Agood crystal inawell-designed mixer will have anoise temperature Tthat isonly slightly more than 1.This means that the over-all noise figure isreduced indirect proportion tothe reduction ini-fnoise figure. Hence itisimportant todesign thei-famplifier tohave anoise figure that approaches asnearly aspossible thetheoretically perfect value of1.. 
 Through processing with the proposed method, the PSLR and ISLR of the image reached−31.07 dB and−29.36 dB, respectively, which were much lower than the other two images. Overall, it could be concluded that the proposed method can suppress azimuth sidelobes splendidly with the maintained azimuth resolution. Simulations with three point targets with di ﬀerent RCSs illustrate the advantages of the proposed method for detecting weak scatterers. 
 PLER RADARS  #OURTESY OF !MERICAN -ETEOROLOGICAL  3OCIETY &ROM $% +INGSMILL AND 2 - 7AKIMOTO  h+INEMATIC  $YNAMIC  AND 4HERMODYNAMIC !NALYSIS OF  A  7EAKLY  3HEARED  3EVERE  4HUNDERSTORM  OVER .ORTHERN  !LABAMA v  -ONTHLY  7EATHER  2EVIEW   VOL   P     . £°ÎÈ  2!$!2 (!.$"//+  OF THE ORDER OF  KM 4HERE ARE SEVERAL REASONS FOR THIS 4HE FINITE BEAMWIDTH LIMITS THE  RESOLUTION AVAILABLE AT LONGER RANGES !T SHORTER RANGES  THE LARGE SOLID ANGLE THAT MUST BE SCANNED IN ORDER TO COVER ALL REGIONS OF A STORM REQUIRES TOTAL SCANNING TIMES OF THE ORDER OF  TO  MIN EVEN  FOR WELL 
 An antenna having multiple beams can also be . used to allow deletion of the beam containing the jammer and still maintain de- tection capabilities with the remaining beams. Increased angular resolution of jammers in the main beam can be reached by resorting to spectral analysis algo- rithms, commonly referred to as superresolution techniques. 
 Under  disturbed conditions, performance may be markedly inferior to that predicted. The Jindalee Radar Performance Model . The Jindalee Radar Performance  Model draws on several unique databases. 
 Inpractice thisisonlyanapproxima­ tion.Electromagnetic radiation doesn'talwaysrespectsllchanassumption. Current inone clement willaffectthephaseandamplitude ofthecurrents inneighboring elements. Ina planararray.thecurrentataparticular element mightbeinfluenced significantly byarela­ tivelylargenumberofitsneighbors (perhaps from20to100).Sincethephasesandamplitudes ofthecurrents ateachoftheelements changewiththescanangle,theeffectsofmutual coupling alsochangewithscanangleandcomplicate theproblem ofcomputing andcompen­ satingcoupling effects.Mutualcoupling, therefore, causestheactualradiation patterntodiffer fromthatwhichWOUld.bepredicted fromanarrayofindependent radiators. 
 CLUDES THE USE OF PULSE 
 and from adjacent range gates. As many as 20 hit-reports might be generated by a single  large target.43 A post processor groups together all reports which appear to originate from the  same target and interpolates to find the best azimuth, range, amplitude, and radial velocity.  The target amplitude and doppler are used to eliminate small cross section and low-speed  angel echoes before the target reports are delivered to the automatic tracking circuits. 
 Itisapparent from Eq. (1)that another consequence ofthe inde- pendence ofthetwo links isadifferent law fortherelation between signal strength and range. Radar echoes vary inpulse power asthe inverse fourth power ofthefree-space range, whereas beacon replies vary only as the inverse square. 
 S. L. Johnston, “Philosophy of ECCM utilization,” Electron. 
 Lopez, A. R., and W. W. 
 Ascope photograph showing the ability ofthe equipment toresolve closely-spaced targets isshown asFig. 6.38. FIG.6.3S—ROW ofsmall ships (LCI’S information offHonolulu) shown onmicro-B of .4N/TPG-l. 
 27, 1934.  7. Vieweger, A. 
 2ADAR 3ONAR .AVIG  VOL   NO   PP n  *UNE   0 % (OWLAND  h&- 
 MATE WHOSE STANDARD DEVIATION IS ON THE ORDER OF CENTIMETERS WHICH  IN PRACTICE  DEGRADES WITH INCREASING SIGNIFICANT WAVE HEIGHT  /NE 
 Similarly, other types offilters could beused toregulate with respect tothe average value ofoutput voltage, ortosome chosen value between peak and average. The filter introduces atime constant that, insome cases, istoo long toachieve the desired rate ofresponse. The second voltage-sensitive element, developed byBell Telephone Laboratories, was abridge network made ofthermistors and excited from alternating current. 
 ING SIGNALS IS GIVEN BY   3.2 D"0# .) !$# !$#  L O G ¤ ¦¥³ µ´     WHERE  0)   INTERFERENCE POWER AT !$ CONVERTER INPUT  #   CREST FACTOR  .!$#   !$ CONVERTER NOISE 4HE CREST FACTOR IS THE PEAK LEVEL THAT CAN BE HANDLED WITHIN THE FULL 
 3. Westerfield, E. C., R, H. 
 BER OF DATA POINTS TO OBTAIN AN ANSWER VALID FOR CLUTTER DISTRIBUTED IN RANGE )N ADDITION TO THE AMPLITUDE AND PHASE NOISE OF THE RECEIVER 
 Ground based SAR interferometry: A novel tool for Geoscience. In Geoscience and Remote Sensing New Achievements. InT ech 2010 .[CrossRef ] 4. 
 Wu, The Scattering and Diffraction of Waves , Cambridge, MA: Harvard  Universities Press, 1959. 79. R. 
 267-270, July, 1957.  24. King. 
 TION WILL ALSO NOT BE DISTURBED  0HASED 
 It can be even greater at higher frequencies. Therefore, to penetrate 10 miles  within the diffraction region, the radar power at 500 MHz must be increased by at least 20 dB  over that required for free-space propagation.  The decrease in radar coverage due to the attenuation of electromagnetic energy in the  diffraction region is illustrated by Fig. 
 Leith, “Side-looking airborne radar,” Scientific  American , vol. 237, pp. 84–95, 1977. 
 MENT THEME  TAKEN IN A BROAD SENSE 4HESE THEMES ARE %ARTH 
 Not all of these mechanisms are revealed in the characteristics of the selection of  simple and complex targets, as shown in the next section. 14.2 THE CONCEPT OF ECHO POWER Definition of RCS . An object exposed to an electromagnetic wave disperses  incident energy in all directions. 
 In the series arrangement of Fig. 8.4~ where the signal is fed from one end, the  position of the beam will vary with frequency (Sec. 8.4). 
 LeeReaulator.—The Lee speed regulator isacentrifugal device which alternately opens and closes ashort circuit across afixed resistor in series with the motor field. The short-circuiting contacts are onthe centrifugal device and can besettoopen and close atany predetermined speeds within 5per cent ofeach other. Speed regulation istherefore good; itcan bemaintained atapproximately 5per cent. 
 TION SHAFTS AND UPDRAFT CORES  WITH HORIZONTAL DIMENSIONS OF THE ORDER  TO  KM  A n  BEAM IS REASONABLY WELL MATCHED TO THESE ATMOSPHERIC PHENOMENA BEING OBSERVED OUT TO RANGES OF A FEW HUNDRED KM 3HORTER 
 Inorder tomap the ground the transmitted energy must be directed toward the ground, and rather than having the energy beamed like asearchlight, a“fan beam” must beemployed asshown inFig. 9.6 forcomplete coverage. Auniformly intense map isdesired, which will display ground objects that lieatdepression angles between, forexample, 5°and 70°below thehorizontal. 
    . È°Óä  2!$!2 (!.$"//+  ! TRULY COHERENT RADAR GENERATES ALL FREQUENCIES  INCLUDING ITS INTER 
 Antweiler, “Polyphase Barker sequences,” Electronics Letters , vol. 25, no. 23,   pp. 
 IEE Proc. Radar Sonar Navig. 2006 ,153, 279–288. 
 As mentioned, the  Luneburg lens can be used as a beam-forming network to form multiple beams in conjunction  with a circular or spherical array, 108 or the lens can be used directly to generate multiple  beams. Since the Luneburg Jens is not generally capable of high power, it is primarily a  receiving antenna. For transmission, it can acl at low power as an analog computer for the  high-power spherical lens. 
 402--408, D. Van Nostrand Company, Inc., Princeton, N.J., 1955.  12. 
 TO 
 Sensors 2019 ,19, 1529 4. Inﬂuence of Radar Look Direction and Wind Field on SAR Eddy Imaging In this section, the images under different radar look directions, wind directions and wind speeds were generated by the proposed simulation method to analyze their inﬂuence on SAR eddy imaging. Brightness varies not only along the eddy spirals but also throughout the SAR eddy image. 
 They can also  have reduced noise and less phase sensitivity to deviations in voltage, which aids in the  detection of low cross-section moving targets in clutter. Compared to a crossed-field  amplifier, they have a larger dynamic range. Compared to a TWT, they are capable of  higher peak and average powers, and they are less sensitive to vibrations. 
  
 Alternatively, it may be accept - able to employ a dual-purpose waveform, able to support two distinct missions, though  with suboptimal performance, or for the transmit system to radiate multiple orthogonal  waveforms for simultaneous reception and processing at a proportional loss of average  power on each transmission but without loss of spatial directivity. But even if these  approaches are sometimes applicable, it is almost always necessary to schedule the  various tasks such that acceptable revisit times are maintained on important missions,  with low priority tasks, such as weather monitoring, activated less frequently, and  challenging tasks activated when suitable propagation conditions occur .151 One other important issue arises with resource management and that is the abil - ity to diagnose faults and failures as soon as they occur. Not only is this necessary   to hasten the repair procedure, but also it enables the radar to adapt its configuration to  do the best it can with impaired equipment. 
 The  feed-support structure and the reflector stiffening structure must maintain the feed  location and surface dimensions while the antenna is being rotated. This dimensional  stability must be maintained through wind loading, temperature variations, or other  environmental factors to ensure that pattern performance is maintained.−1.50−1.25−1.00−0.75−0.50−0.250.00 −25 −20 −15 −10 −5 Transmission Loss in dBLeakage Loss in dB FIGURE 12. 9 Reflector leakage loss vs. 
 . Radar System Engineering  Chapter 9 – Synthetic Aperture Radar  73            Figure 9.5  Comparison of analog and Digital Beam -forming.     . 
 Thesupporting framework canalsobeofsteeloraluminum members ratherthanplastic.Metalspace-frame radomes can beoflargesize,150-ftdiameter beingquitepractical. Designs upto500-ftdiameter havebeen considered. Thecrosssectionofmetallic members canbesmallerthanthatofdielectric members ofequivalent strength; hence, t~eeffectofaperture blocking isless.Metalmembers arenotonlysuperior inelectrical performance totheequivalent dielectric members butmetal space-frame radomes aregenerally cheaperandeasiertofabricate, transport, andassemble, andcanbeusedforlargerdiameter configurations. 
 tais the azimuth slow time. The deramping function is described as (2). s(ta)=rect/parenleftbiggta Ts/parenrightbigg exp/parenleftBig −jπfdr,bt2 a−jπf3rd,bt3 a/parenrightBig , (2) where fdr,band f3rd,brepresent the calculated Doppler rate and the derivative of the Doppler rate, respectively, which are inaccurate. 
 164  Constant-false-alarm-rate receiver (srr CFAR)  Const rained feed, 306-308  Constrained lens. 25 1  Control electrode, CFA. 2 1 1  Convective cell, 5 10  Conversion efficiency, 19 1  Conversion loss, mixer, 347  Cookie cutter tuner, 199  Corporate feed, 285  Correlation detection, 375-376  Correlation function, 373  Correlation time, sea echo, 484-485  Cosecant-squared antenna, 55-56, 258-261  Cosmic noise, 461  COSRO, 159  Coupled cavity TWT, 207  Coverage pattern, elevation, 446-447  Cross-correlation receiver, 375  Cross level, antenna, 273  Cross section (see radar cross section)  Cross talk, in tracking radar, 158  Crossed-field amplifiers, 208-2 13  Crossed linear polarization, 506  Crowbar, for tube protection, 216  Crown-of-t horns tuner, 199  CRT screens, 355-357  Cumulative probability of detection, 64  CW radar, 68 -8 1  CW wave-interference radar, 9  Data stabilization, antenna, 270  d-c operation, of CFA, 21 1  Decorrelation time, sea echo, 484-485  Decoy, 553  Delay-line canceler, 104, 106- 1 14  Delay lines, pulse compression, 424-426 Delta-a scanner. 
 Taylor. S. A., and J. 
 The disadvantages of phase-comparison monopulse compared with amplitude-comparison mono- pulse are the relative difficulty in maintaining a highly stable boresight and the difficulty in providing the desired antenna illumination taper for both sum and difference signals. The longer paths from the antenna outputs to the comparator circuitry make the phase-comparison system more susceptible to boresight change due to mechanical loading or sag, differential heating, etc. A technique giving greater boresight stability combines the two antenna out- puts at RF with passive circuitry to yield sum and difference signals, as shown in Fig. 
 Kovaly, J. J.: "Synthetic Aperture Radar," Artech House, Inc., Dedham, Mass., 1976. (A colIcction of  33 reprints covering the development, theory, performance, effect of errors, nlotion compensation,  processing, and application of SAR.)  2. 
 TEN AS 7+X  +Y  4HIS IS CALLED THE  DIRECTIONAL WAVE SPECTRUM  AND EXPRESSES THE ASYM 
       .   '2/5.$ 0%.%42!4).' 2!$!2   Ó£°£x &)'52%   'RAPH OF PROBABILITY OF DETECTION AS A FUNCTION OF TARGET RANGE IN MILLIMETERS AND  TARGET DIAMETER  MM LEFT 
 It was noted,jO however, that the propaga-  tion of clectrornagrietic energy from antennas well below the duct is greater than would be  predicted from classical ray theory. One explanation postulated for explaining this  discreparicy is that energy can be scattered into and out of the elevated duct by irregularities in  the iridex-of-refractio~i profile.  Evaporation duct. 
 7.5, McGraw-Hill Book Company, New York, 1950.  32. Middleton, D.: Statistical Theory of Signal Detection, IRE Trans., no. 
 The connection between gain and beamwidth iseasily seen. Using anaperture ofdimensions dinboth directions, abeam may beformed whose angular width, 1determined bydiffraction, isabout X/dradians. The radiated power isthen mainly concentrated inasolid angle ofX2/dZ. 
 10.1. Construction.-Microwave magnetrons, orcavity magnetrons asthey arefrequently called, arebasically self-excited oscillators whose purpose istoconvert thed-cinput power into r-foutput power. Figures 10.1 and 10.2 show aparticular design ofa10-cm magnetron which is typical ofthk class oftransmitting tubes. 
 Usinganargument similartothenonscanning arraydescribed previously, gratinglobes appearatanangleOqwhcnever thcdcnominator iszero,orwhen n:~(sinOg-sinOu)=±lin: (H.lOa) IsinOg-sin00I=A(R.IOh) or +11-d IIagratinglobeispermitted toappearat-90°whenthemainbeamissteeredto+90°,itis foundfrollltheabovethatd=A/2.Thustheelement spacing mustnotbelargerthana halfwavelength ifthebeamistobesteeredoverawideanglewithout havingundesirable grating lobesappear. Practical arrayantennas donotscan±90°.Ifthescanislimitedto -1.:60°.Eq.(H.IO)statesthattheelement spacing shouldbelessthan0.54,tNotethatantenna elements usedinarraysaregenerally comparable toahalfwavelength inphysical size. Changeofbeamwidth withsteering angle.Thehalf-power beamwidth intheplaneofscan increases asthebeamisscanned offthebroadside direction. 
 J. D.: "Antennas." McGraw-Hill Book Company, New York, 1950 .  . 
 D. K. Barton, Radar Systems Analysis , Englewood Cliffs, NJ: Prentice-Hall, 1964. 
            
 The Rayleigh is actually a member of the Weibull family, and results when  a = 2. The exponential pdf is also a member of the Weibull family when a = I. (Further  discussion of the Weibull pdf is given in Sec. 
 Unfortunately, this will also cause  the ratio detector to declare false alarms in the presence of narrow-pulse interference.  To reduce the number of false alarms when narrow-pulse interference is present, the  individual power ratios can be soft-limited24 to a small enough value so that interfer - ence will cause only a few false alarms. A comparison of the ratio detector with other  commonly used detectors is shown in Figures 7.15 and 7.16 for nonfluctuating and  fluctuating targets. 
 CESSING  WHICH CAN INCLUDE THE FORMATION OF MULTIPLE SIMULTANEOUS BEAMS FORMED WITH APPROPRIATE APERTURE ILLUMINATION WEIGHTING  AND ADAPTIVELY DERIVED NULLS IN THE BEAM PATTERNS TO AVOID SPATIAL INTERFERENCE OR JAMMING ,IMITATIONS ARE DUE TO THE AVAILABILITY AND COST OF ANALOG 
 Asacorollary, itisalso true that many troubles attributed tomagnetrons result from afailure touseproperly theinformation pro- vided byaRieke diagram. 10.5. Magnetron Characteristics Affecting Over-all Systems Design. 
 (2.1) but which have an effect on  the radar performance are the meteorological conditions along the propagation path and thc  performance of the radar operator, if one is employed. The statistical nature of these several  parameters does not allow the maximum radar range to be described by a single number. Its  specification must include a statement of the probability that the radar will detect a certain  type of target at a particular range. 
 It has been reported'' that at X band, small ships stand  out much better with a 2" horizontal beamwidth antenna than when illuminated by a 0.85"  beamwidth antenna. This is contrary to what would normally be expected if the clutter were  uniform. 3  Thus, as the resolution cell size is decreased the nature of the sea clutter changes. 
 The basic theory of SAR assumes that the  ground (scene) is stationary. A moving target in the scene will have a “wrong” rela - tionship between its location and its line-of-sight velocity. If the target motion is in a  straight line at constant speed, the target image will be displaced in crossrange by  rV V R VdisplLOS L OS= =Ω (17.40) where Ω is the apparent rotation rate of the scene relative to the radar and VLOS is the target  velocity component along the radar line-of-sight. 
 = × −  −2 5 10 0 5730 5 1 5 N tt (26.7) where lmax is the maximum frequency trapped, dN is the refractive index change  across the duct, and t is the duct thickness.4 In addition to extended radar ranges, atmospheric ducts (and other propagation  effects such as multipath interference) have other significant impacts upon radar per - formance. These effects may be visualized with the aid of a height versus range graphic  available from an assessment system such as AREPS. Such a graphic is shown in  Figure 26.2. 
 BAND SLOTTED ARRAY )T IS MOUNTED INSIDE A RADOME UNDERNEATH THE FUSELAGE OF AN % 
 Analysis shows that when the drive output irn-  pedance is srnall, the effect of temperature-caused variations in the increment of magnetization  will l>c s111:1Il.  Ilual-niode ferrite phase shifters, There are sorne applications which require a reciprocal pliase  sliifter. Ac t~leritioned previously the Reggia-Spencer phase shifter is reciprocal but has limita-  tions such as slow switching speed. 
 With deep networks, the images with data augmentation can be trained effectively. Theseresults in Table 6suggest that the proposed method is able to give more target details of the input image for training, it has 3% higher accuracies compared to the method which used random crop and have almost 4% higher accuracies compared to the method which used traditional ways of data augmentation. These results proved that our method is partly corrected. 
 ch16.indd   6 12/19/07   4:54:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars.  SPACE-BASED REMOTE SENSING RADARS  18.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 where TR is the (slant) range swath depth of the antenna pattern and BDop is the cor - responding doppler bandwidth. To first order, the azimuth resolution is given by  rRN BL Az Az Dop=b T (18.8) where b is the azimuth beamwidth, R is slant range, NL is the number of looks (here  assumed to be taken in the azimuth domain), and ( TAz BDop) is the azimuth time- bandwidth product, comprised of the illumination time of the target, and its doppler  bandwidth. 
 Thatis,iftheregionfrom0to1200isscanned first,thenext regiontobescanned isfrom240to360°,followed bytheregionfrom120to240°.. Figure 7.14 Configuration of the mirror-scan antenna for obtaining 360" scanning without RF rotating  jo~nts. (From B. 
 TARGET TRACK  TO PREVENT SPURIOUS SIGNALS  WHICH DEGRADE PERFOR 
 W.: Aperture-antenna Analysis, chap. 9 of "Radar Handbook," M. I. 
 D" BEAM 
 wAvE~oR~s—Chance, Hughes, Mac.NTichol,. Sayre, and Williams 20. ELECTRONIC TIME Measurements—Chance, Hulsizer, .Wac.Yichol, and Williams 21. 
 They may be subject to considerable variation and  uncertainly. Although the loss associated with any one factor may be small, there are many  possible loss mechanisms in a complete radar system, and their sum total can be significant.  In this section, loss (number greater than unity) and efficiency (number less than unity)  are used interchangeably. 
 M.: DOPLOC Uses Phase-locked Filter, Electronic Ind., vol. 18, pp. 96-99, October,  1959. 
 E'x0 E'y0y xz IεI Ex0τ Ey0   Figure 11.2  Polarization ellipse.   The angle of ellipticity ε is defined b y the axial relationship m between the semi -major and  semi- minor axes of the ellipse.  . 
 H. V., and J. H. 
 The i-famplifier band- width isnot animportant factor in the choice ofthe intermediate fre- quency. Itisjust aseasy toachieve abandwidth of,forexample, 5Me/seeI atacenter frequency of5Me/see asit=E+ FIG. l?.6.—Single-tuncd i-famplifier. 
 Considerations such asthese ledtothe development ofmeans for reproducing radar displays atadistant point bytransmitting the radar video signals and appropriate synchronizing information bymore orless conventional radio practice. The technical problems of“radar- relay, ” asthis iscalled, have been worked out, and systems forthe purpose are discussed indetail inChap. 17. 
  
 The standard deviation of the clutter power spectrum crc, in hertz, is 2avac = — Hz (15.4) A. where X is the transmitted wavelength, in meters; and av is the clutter standard deviation, in meters per second. Antenna scanning also causes a spread of the clutter power spectrum because of amplitude modulation of the echo signals by the two-way antenna pattern.2 The resulting clutter standard deviation is ac = ^El x£ = 0.265 ^ Hz (15.5)TT n n where/,, is the PRF and n is the number of hits between the one-way 3 dB points of the antenna pattern. 
 2. Extremely wide bandwidths achievable.Comments . FIG. 
 ENT IN THIS PROPAGATING ENERGY AS A DISTORTION OF THE PHASE FRONT 4HEORETICAL PLOTS OF A DISTORTED PHASE FRONT FROM DUAL SOURCES COMPARE VERY CLOSELY WITH PHOTOGRAPHS OF THE PHASE FRONT OF THE RADIATING SURFACE RIPPLES IN THE RIPPLE 
 46, pp. 476-481, February 1958. 36. 
  
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°Î AND FOR LARGE SIGNALS !I    R   IT REDUCES TO THE LINEAR DETECTOR  !X 4II IN  £     &OR CONSTANT SIGNAL AMPLITUDE IE   !I   !   THESE DETECTORS WERE FIRST STUDIED BY  -ARCUM AND WERE STUDIED IN SUCCEEDING YEARS BY NUMEROUS OTHER PEOPLE 4HE MOST  IMPORTANT FACTS CONCERNING THESE DETECTORS ARE THE FOLLOWING L 4HE DETECTION PERFORMANCES OF THE LINEAR AND SQUARE 
 The most difficult ofthese operations isamplification. If statistical noise and weak moving-target signals are tobefully visible, they must reach thefinal video rectifier atalevel sufficient tocause linear operation ofthat detector. Since the noise level atthe cancellation detector may beasmuch as40dbbeneath the signal peak, again of several hundred may berequired between cancellation and rectification. 
 Second, theamplifier that precedes thelimiter isgiven aresponse that is arising function offrequency. The spurious signals, being largely of. SEC, 59] ML’LTIPLE-TARGET F-M RANGE JIEALSCRE.llEIVT 147 frequency Iowerthan thedesired signals, arethus discriminated against. 
 After delivering their d-c energy to the RF field, the electrons are removed by  the collector electrode. The RF signal to be amplified enters via the input coupler and propa·  gates along the slow-wave structure. A helix is depicted as the slow-wave structure in Fig. 
 PLES ARE ACQUIRED OVER AN INTERVAL  4  WHICH MAY EXCEED  S  THOUGH IT IS USUALLY  IN THE RANGE OF n S 7AVELENGTH  K  4HE WAVELENGTH OR OPERATING FREQUENCY MUST BE SELECTED SO THAT  THE TRANSMITTED ENERGY IS REFLECTED BY THE IONOSPHERE TO ILLUMINATE THE DESIRED AREA  OF THE %ARTH 4HE SPECTRUM OF THE EMISSIONS MUST BE CONSTRAINED NOT TO INTERFERE WITH OTHER USERS "ECAUSE BOTH THE IONOSPHERE AND THE (& 
  AND FOUR 
 BASED 3!2S 0!,3!2S  MODES &IGURE   INCLUDE STANDARD SINGLE 
 Considerable waveguide was used in this design. To  prodtrce the 333 iridependent beams, the Blass height finder employed 30 miles of S-band  waveguide.  Butler beam-forming array." loo Another RF beam-forming device is the parallel network  attributed to Butler, and independently discovered by Shelton. 
 Similar  translational effects can occur. The polarization produced by an applied field (such as  a propagating radar wave) is closely related to the thermal mobility of the molecules  and is, therefore, strongly temperature dependent. Note that polarization in this context  is different from the polarization of EM waves. 
   -   I  
 Interferometry with ALOS-2 full-aperture ScanSAR data. IEEE T rans. Geosci. 
 M. Purduski, “A radar clutter model: average scattering coef - ficients of land, snow, and ice,”  IEEE Trans. , vol. 
 The antenna is mounted so that it can be positioned in both azimuth and  elevation by separate motors, which might be either electric-or hydraulic-driven. The antenna  beam is offset by tilting either the feed or the reflector with respect to one another.  One of the simplest conical-scan antennas is a parabola with an offset rear feed rotated  about the axis of the reflector. 
 The middle stages are usually the  ones controlled since the first stage gain should remain high so as not to influence the noise  figure of the mixer stage. It is also best not to control the last IF stage since the maximum  undistorted output of an amplifying stage is reduced when its gain is reduced by the applica-  tion of a control voltage.  An alternative AGC filter design would maintain the AGC loop gain up to frequencies  much higher than the conical-scan frequency. 
 136. F. M. 
 Soc ., vol. 74, pp. 1669–1687, 1993. 
 53. A. Ferretti, C. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 For two pulses separated in time by the interpulse period T, the complex correlation  coefficient between two clutter returns is  ρ π σ πT f d T j f T = − ( ) ⋅ − exp exp( ) 4 22 2  (2.32) The second factor in this expression represents the phase shift caused by the doppler  shift of the clutter returns. For a known target doppler shift, the received target return can be represented by  an N-dimensional vector:  s f= ⋅AS (2.33) where AS is the signal amplitude and the elements of the vector f are fi = exp [ j2pfsti]. 
 Such a diode is ordi- narily used as the second detector of a superheterodyne radar receiver. Also, ap- preciable RF and IF gain usually precedes the second detector, so that the volt- age applied to it is usually large enough (typically, an appreciable fraction of a volt) to ensure this "linear" type of operation. A square-law detector is one that has the nonlinear characteristic /O = CtV;2 (2.26)DETECTABILITY FACTOR D0 (DECIBELS) . 
 TARGET RETURNS MUST USUALLY FOLLOW THE RETURN  FROM THE JAMMER 
 This is probably justified when operators are alert, motivated, and well trained. It is also  justifled when automatic (electronic) detections are made without the aid of an operator.  When the operator does introduce loss into the system, it is not easy to select a proper value to  account for it. 
 72. Haddock, F. T.: Scattering and Attenuation of Microwave Radiation Through Rain. 
 IEEE, vol. 65, pp. 1470-1504, October, 1977. 
 Phase-comparison monopulse. The tracking techniques discussed thus far in this chapter were  hased on a comparison of the m1111lit11des of echo signals received from two or more antenna  posit ions. The sequential-lobing and conical-scan techniques used a single, time-shared  a11tl'1111a hcam. 
 SIDELOBE ANTENNAS &OR THE CASE IN WHICH THE DESIGN SIDELOBES ARE  WELL BELOW THE SIDELOBES CAUSED BY ERRORS  !LLEN HAS DEVELOPED THE SET OF CURVES SHOWN IN &IGURE  !N EXAMPLE WILL ILLUSTRATE THE USE OF THESE CURVES )F YOU DESIRE TO HOLD THE SIDELOBE AT A GIVEN POINT IN SPACE TO LESS THAN  D" BELOW THE PEAK OF THE BEAM WITH A PROBABILITY OF   DRAW A VERTICAL LINE FROM  
 Asthe beam sweeps over theground, new elements areilluminated and theoldones pass outofthe beam. Thus the signal fluctu- ates inboth amplitude and phase, asshown in Fig. 16.20, where Risthe signal voltage ata given instant and R’thevalue after onerepeti- tion period. 
 RANGE SUR 
 pp. 30-34, June/July, 1975.  20. 
 Point K is located on a stable surface. Points H, I and J subside greatly over time compare to point K. In addition, there is a correlation between subsidence and impervious surface fraction, see Figure 13. 
 LAW VARIATION OF INTENSITY THAT IS  THE DIFFERENTIAL SCATTERING COEFFICIENT VARIES AS COS P  WITH P  BEING THE ANGLE OF INCI 
 IEEE T rans. Geosci. Remote Sens. 
 MITS THAT IS  THE RECEIVER NOISE FIGURE SHOULD BE GOOD ENOUGH TO MAKE ENVIRONMENTAL NOISE THE LIMITATION !N EXAMPLE OF THE ##)2 2EPORT  DATA WILL NOW BE DISCUSSED &IGURE   WAS DRAWN FROM ,UCAS AND (ARPER  .OISE POWER IN A  
 Tlie height resolution depends on the antenna beamwidth, as in a conventional frequency-  scan aritenna; but the range resolution is determined by the frequency spectral components.  received froni a given elevation angle, that corresporid to one beaniwidth. As stated in Sec. 
 df df l  Nn = d00 On = dOo D (8.22)  where (18 = heamwidth and IJ = aperture dimension. Substituting E4. (8.18) into the above  gives  f cos 00  ti.fR = .f~ {//d)(D/c) (8.23)  The time 111 ror the signal to transit the snake reed from one end to the other is equal to  (//d)(D/c). 
 Newliouse: A Terrain Clearance Indicator. Bell Sys. Teclr. 
 The gain is that due to the actual number of elements NGe(Q), but the beamwidth is that of the full aperture. For example, if the array has been thinned so that only 10 percent of 6 (degrees) (b) FIG. 7.13 (a) Thinned array with a 4000-element grid containing 900 elements, (b) Typical pattern for a thinned array. 
   OR OR       !N EXAMPLE IS SHOWN IN 4ABLE  )F MORE THAN TWO TARGETS ARE ENCOUNTERED DURING A DWELL TIME  GHOSTS AGAIN RESULT  AS  ONLY .  
 Inorder that the trigger signal shall beproperly timed when decoded atthe receiver, the 1Since this interval istoo narrow toallow rapid “looking in” initially orafter tracking has been lost, the circuits arearranged inamamcr not shown sothat inthe abaence ofpulses the grid remaine on.. t?iEc.17.8]PULSE METHOD FORRELAYZIVGSINEANDCOSINE i I I I I I I I I I I I I I I I I I I I I I I I+++ I I IiI I }-i .——----- I I i L--_-l——-----—--- J ----------,. 710 RADAR RELAY [SEC.17.8 actual modulator trigger isdelayed from thesignal tothecoder byatime equal tothat occupied bythe code. 
 Cahoon: Tlic Use of Surface Weather Observations Lo Predict the Total  Atmosplieric Rending of Radio Rays at Snlall Elevation Angles, Proc. IRE, voi. 45, pp. 
 TIONS IN THE FORM OF THE LIQUID 
 C. Currie: Backscatter from Ground Vegetation at Frequencies  Between lO and 100 GHz. /976 IEEE Antennas and Propagation Society Sj•mposi11m. 
 44. P. Rosen, S. 
 (From  Brisrol, l2 Courtesy Proc. 1 EEE.)  424INTRODUCTION TORADAR SYSTEMS withanapplied voltage; theso-called serrasoid modulator 16whichgenerates aquadratic waveform andcompares thiswitharepetitive sawtooth wavetogenerate pulsesthathaveat1 variation inspacingwhicharefilteredtoformalinear-FM waveform; atappeddelay-line with nonuniform tapspa~ings determined bythe positive-going zerocrossings ofthedesiredlinear­ FMwaveform, followed byafiltertoformtheoutputwaveform; asynthesizer 17which combines astaircase frequency waveform withtheaverage desiredslope,andasawtooth frequency waveform whichfills-inthestepswithashortlinearFM;orbydigitalmeansin whichanalgorithm performs adoubleintegration toproduce aphaseattheoutputofthe generator whichvariesasthesquareoftime,asrequired foralinearFM.18Thedigital generator hastheadvantage offlexibility intheselection ofbandwidth andtimeduration, as wellasgoodstability andlowresidual generation errors.Theabovearesometimes called activemethods forgenerating waveforms. ThelinearFMwaveform mayalsobegenerated bypassivemethods suchasbyexcitinga dispersive delaylinewithanimpulse. 
  -ULTI 
 Thus no feedback or feedforward path need span more than two delay elements. This  type of corifiguratiorl is sometimes preferred to the canonical configuration.  The synthesis technique described by White and Ruvin may be applied with any k~iown  low-pass filter characteristic, whether it is a Butterworth, Chebyshev, or Bessel filter or one of  the filters based on the elliptic-function transformatibn which has equal ripple in the rejection  band as well as in the passband. 
 Hitschfeld: The Interpretation of the Fluctuating Echo for Ran- domly Distributed Scatterers, pt. I, Can. J. 
 227-232. ·  44. Valenz~la. 
 New York, 1968.  31. Nairn. 
 SARY FOR THE FILTER NOTCH TO TRACK THE DOPPLER 
 From orbital altitudes and from a realistic  spacecraft, it is not feasible to transmit a simple short pulse that has sufficient energy  to generate useful reflections from depth. Long modulated pulses are the only practical  method. Unfortunately, the specular component of surface reflection usually is very  strong at the long wavelengths required for subsurface sounding. 
  
 PHASE )   AND QUADRATURE 1  COMPONENTS AT BASEBAND REPRESENT THE REAL AND IMAGINARY PARTS   RESPECTIVELY  OF A COMPLEX NUMBER WHOSE COMPLEX ARGUMENT IN PHASOR NOTATION IS THE PHASE DIFFERENCE BETWEEN THE TRANSMITTED AND RECEIVED PULSES 4HE COMPLEX MODULUS  OR MAGNITUDE  IS PROPORTIONAL TO THE RECEIVED ECHO STRENGTH&)'52%  0ULSE DOPPLER DWELL TIMELINE      
 THE 
 Ruf, “Foreword to the special issue on the WindSat Spaceborne  Polarimetric Radiometer—calibration/validation and wind vector retrieval,” IEEE Transactions  on Geoscience and Remote Sensing , vol. 44, pp. 467–469, 2006. 
 The stabiliza-  272INTRODUCTION TORADAR SYSTEMS Elevation axjs aXIs-\cr05s­ elevallon 01'.15 Train axisTrain aXIs (0)One-axis mount (b)Two-axis mount Type1(c)Two-axIs mounl Type2 .,l Roll axisElevation axis (level) Train axisElevallon axis ---------TrOinaxis ld)Two-axis mount Type3(e)Three-axis mount Type1(f)Three-axis mount Type2 Elevation axis Cross­ -----.,H--!---elevation axis Train axisTrain ~--axis Pitch axis Roll mdsTrain axis __ EI~vation aXIs __PIlCh \_axis Roll axis (g)Three-axis mount Type3(II)Three-axis mount Type4(i)Four-axis mount Figure7.31Arrangements ofaxesforstabilized antenna mounts.(FromCady,Karelitz, andTurtler: .. chap.4,courtesyMcGraw-Hill BookCompany.) rotationabouteachofthefouraxes.Thethree-axis mountof(h)issimpler, butalsohassimilar disadvantages becauseofweightandsize. Intheabove,thestabilization ofthemountwasassumed tobebysomeformofmechanical compensation. 
 These results apply to a ground-based array. If the array is on a ship, the lower limit of the  elevation scan angle must be less than 0° to allow for the roll and pitch orthe ship. (A value of  -20° might be a typical requirement.) The optimum tilt angle of the array would be dilTerent  than if the lower limit were 0°. 
 Also, the radar is more  subject to interference from nearby friendly transmitters.  The first sidelobe nearest the main beam is generally the highest. A typical parabolic  reflector antenna fed from a waveguide horn might have a first sidelobe 23 to 28 dB below the  main beam. 
 is not found at zero frequency as is the case for land backscatter, but is centered at two discrete  frequencies symmetrically spaced around zero, Fig. 14.8. The sea may be thought of as  composed of a large n1Jmbtr of individual wave trains, each with a differl!nt wavelength and  amplitude and traveling in different directions. 
 30. Preprints and Proceedings of Conferences on Radar Meteorology , 1947–present, Boston: AMS. 31. 
 The plane in which monopulse information is measured rotates. Consequently,log (22+ A2) «2 log I.2 VIDEOTO RANGESERVOANDDISPLAYS MIXERLOG DETECTOR HYBRID MIXERLOG DETECTOR , /2 + A\ 2A log IT^A )*-r MlCROWAVERESOLVERA= SAZ cos ^s1" "*" ^EL s'n ^s"1" REFERENCE SIGNAL ANGLEDEMODULATORCOMPARATOR . elevation and azimuth information is sequential and must be separated for use in each tracking coordinate. 
 57. I3rnun. t! i I.: Ratliatic,n ('liaracteristics of the Spherical Luneburg Lens, IRE Trnrls.. 
 The sidelobe level for the periodic case is constant at a value of — 1. The periodic autocorrelation function is repetitive with a period of NT and FIG. 10.10 Autocorrelation functions for (a) the periodic case and (b) the aperiodic case.(a)(b)Number of stages, n 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20Length of maximal sequence, N 3 7 15 31 63 127 255 511 1,023 2,047 4,095 8,191 16,383 32,767 65,535 131,071 262,143 524,287 1,048,575Number of maximal sequences, M 1 2 2 6 6 18 16 48 60 176 144 630 756 1,800 2,048 7,710 7,776 27,594 24,000Feedback-stage connections 2,1 3,2 4,3 5,3 6,5 7,6 8,6,5,4 9,5 10,7 11,9 12,11,8,6 13,12,10,9 14,13,8,4 15,14 16,15,13,4 17,14 18,11 19,18,17,14 20,17 . 
 15.8 Further decrease ofbearnwidth below 1°should beadvantageous operational}+, although improvements due toincreased resolution may not beasmarked inthis region asthey were intheregion above 1°. If wavelength isdecreased below the 10-cm region tosharpen the beam, coverage requirements will become more difficult tomeet, even with the assumption that component performance isindependent ofwavelength. Because ofcoverage demands and forother reasons tobediscussed later, adecrease ofwavelength belo\\- abo~~t 8cmtosharpen the beamwidth does not appear desirable. 
 The plasma panel has also been considered as a bright radar  display capable of incorporating alphanumeric labels.59  Types of display presentations. The various types of CRT displays which might be used for  surveillance and tracking radars are defined as follows:  A-scope. A deflection-modulated display in which the vertical deflection is proportional to target echo  strength and the horizontal coordinate is proportional to range. 
 A radar is usua11y Jess affected by snow and ice than by rain because the factor I K 12 in  Eq. {13.18) is less for ice than for rain, and snowfall rates are generally less than rainfall rates.  Scattering from water--coated ice spheres. 
 Ó£°£ä  2!$!2 (!.$"//+  4HE INTRINSIC IMPEDANCE  G OF A MEDIUM IS THE RELATIONSHIP BETWEEN THE ELECTRIC  FIELD  %  AND THE MAGNETIC FIELD  (  AND IS A COMPLEX QUANTITY GIVEN BY   HWM SWE 
 By October 1942 the ASV Radar Committee had de ﬁned the requirements reproduced from [ 1] in the box below. This re ﬂected the lessons learned from the use of ASV Mk. II and at this time extensive work was underway to improve the performance of ASV systems, as discussed below. 
 C.: Losses Due to Rain oil Radomes and Antenna Reflecting Surfaces, IEEE Trans.,  vnl. Af-I?. pp. 
 Attwood: "Radio Wave Propagation, Consolidated Sum- mary Technical Report of the Committee on Propagation, NDRC," Academic Press, New York, 1949, p. 219. 28. 
 The scale of probabil-  ity ranges from 0 to 1.t An event which is certain is assigned the probability 1. An impossible  event is assigned the probability 0. The intermediate probabilities are assigned so that the  more likely an event, the greater is its probability. 
 285  signal matiagemerit in, 324  sriakc feed for. 301  space-fcd, 308 -309  strharrays in, 309 310  switched-line phasc shiftcr for, 288  thinned, 309, 319, 331 -332  triangular element spacing in, 333-334  twin-slab phase shifters for, 294  unequally spaced, 331-332  ARSR-3, 538-541  Artificial dielectric lenses, 249-252  ASR. 536-537  Asymmetric monopulse, 175  Atmospheric attenuation, 459-461  Atmospheric noise, 461-463  Attenuation in waveguides, 57  Automatic detection, 183-184, 388-392  Automatic detection and track (ADT), 153,  183-186, 392  Automatic gain control, 157- 158  and amplitude fluctuations, 168  and angle fluctuations. 
 When a series of power splitters are used to create a tree-like  structure, as in Fig. 8.2, it is called a corporate feed, since it resembles (when turned upside  down) the organization chart of a corporation. Equal lengths of line transmit the energy to  each element so that no unwanted phase differences are introduced by the lines themselves. 
 degree in Physics from the University of Bari (Italy) in 1997 and 2005, respectively. He was at theUniversity of Bari until 2007, after which he joined the Italian Research Council, where he ispresently a researcher at IREA in Bari. His main research interests include advanced processingtechniques for Synthetic Aperture Radar (SAR) imaging and SAR interferometry and the applicationof multi-temporal/multi-frequency analysis to ground monitoring. 
 The geometry of the inverted coaxial  magnetron makes it suitable for operation at the higher frequencies. Figure 6.5 is an example.  Performance chart and Rieke diagram. 
 2017 ,14, 2280–2284. [ CrossRef ] 13. Zhuge, X.D.; Yarovoy, A.G. 
 So we changed its last layer with output of 3, as shown in Figure 10. The classiﬁer and the fully connected layers should be changed as required. Figure 10. 
 O'Hara, F. J., and G. M. 
 The frequency-response characteristics of many practical radar receivers are such that  tile J-dB and tile noise bandwidths do not differ appreciaoly. Therefore the 3-dB bandwidth  may be used in many cases as an approximation to the noise bandwidth.2  The noise power in practical receivers is often greater than can be accounted for by  thermal noise alone. The additional noise components are due to mechanisms other than the  thermal agitation of the conduction electrons. 
 PALSAR’s 132 modes (Figure 18.4) include  standard single-polarization mapping, ScanSAR, a variety of dual- and quadrature- polarized modes,‡ and experimental or demonstration modes including SpotSAR.  The L band (23 cm) baseline frequency (1270 MHz) has two bandwidths, 28 MHz  (fine-beam single-polarization mode), and 14 MHz (dual-, quad-pol, and ScanSAR  modes). The span of mid-swath incident angles is (7.9 ° –60°). 
 Rampazzo, and G. Rodriguez, “Anticlutter and ECCM design criteria for a low  coverage radar,” Proc. Int. 
 Geophys. Res ., vol. 73, pp. 
 THE 
 In Formula (17), data cannot be processed directly by applying the traditional CS optimal reconstruction algorithm. In [ 28], an improved convex optimization approach was proposed to solve the joint sparse imaging problem of interferometric channels. As sparse reconstruction is only performed for azimuth, the computational complexity is not high. 
 VECTOR IS  PROPORTIONAL TO 2-  K  WHERE THE ROTATION MEASURE 2- IS A FUNCTION OF IONOSPHERIC  ELECTRON DENSITY 4HE IONOSPHERE ALSO INTRODUCES DISPERSION AND  UNDER CERTAIN UNFA 
 ORDER SPURIOUS COMPONENTS 3UCH CHARTS ARE MOST USEFUL IN DETERMINING OPTIMUM )& AND ,/ FREQUENCIES DURING THE INITIAL DESIGN PHASE /NCE THE FREQUENCY PLAN HAS BEEN DETER 
 Furthermore  tlie fibrous-glass-reinforced laminate took about two minutes to dry but the air-inflated  radome material required about 30 to 45 min.  The losses due to rain can be reduced significantly by treating the radome surface to make  it notiwetting. or water repellent."9 I*' Experiments at 4.2 GHz with a 554 rigid metal  space-frame radome at a simulated rain rate of 40 mm/h (a very high rate) had a measured loss  of from 1.0 to 1.7 dB.' l9 When treated to decrease its wettability the loss was less than 0.3 dB. 
 Burrows. C. R.. 
 The larger the squint angle, the more ﬂexible the data acquisition and hence the more information a single observation can achieve. For the very-high-squint (VHS) airborne SAR imaging, targets at different positions have spatially-variant Doppler histories, as shown in Figure 1. While in range (along the direction of electromagnetic wave propagation), the spatial variance can be easily estimated and compensated by range blocking, it is not that convenient to estimate and compensate the azimuth spatially-variant Doppler parameters (along the direction perpendicular to the direction of electromagnetic wave propagation). 
 Airborne weather radars are constrained by size and weight limitations. Ground-based radars may be constrained by cost considerations. Severe storm warning radars require long range and high unambiguous velocity, and they must penetrate very heavy rain, thus dictating long wavelengths. 
 Since the rainfall rate depends upon  two parameters, N0 and Λ, it is not surprising that Eq. 19.47 is not universal. Despite  this fact, Battan20 lists four expressions as being “fairly typical” for the following four  types of rain:    Stratiform rain110 Z = 200 R1.60 (19.50)  Orographic rain111 Z = 31 R1.71 (19.51)            Thunderstorm rain112 Z = 486 R1.37 (19.52)             Snow113 Z = 2000 R2.00 (19.53) Stratiform53 refers to widespread, relatively uniform rain and uses the well-known  Marshall-Palmer drop-size distribution. 
 JPL D-22997, NASA  Earth Science Instrument Incubator Program, JPL, Calif. Inst. Tech., Pasadena, CA, 2002. 
 8.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 Pulse Compression Radar Michael R. 
 P. Howson: Image-Cancelling Mixers at 2 GHz, Electronic  Letters, vol. 10, no. 
 1 I. Rabiner, L, R., and C. M. 
 379 392. August/September 1976.  85. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar.  AN INTRODUCTION AND OVERVIEW OF RADAR  1.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 HF (3 to 30 MHz). 
 Some of these dish antennas employed conical scanning of a single beam to provide the elevation error signal required to accurately center the beam on the target. The accuracy of such a technique is very good but obviously is limited to one target at a time. Conical scanning and lobe switching are special cases of a general technique for developing off- boresight error signals called sequential lobing. 
 1971.  7X. K;rlrr~;irl, R I!: A Ncw Approncl~ lo I .irie;~r 1-ilteritig ant1 Predictiori I'rohler~is, 7'rtrtrs. 
 N. Bringi, and D. Brunkow, “Studies of the polarimetric covariance matrix. 
 BEAM CLUTTER AS LONG AS SOME PART OF THE MAIN BEAM STRIKES THE GROUND 4HE CLUTTER CAN BE CALCULATED AS IN A PULSED RADAR  THEN FOLDED IN RANGE AS A FUNCTION OF THE 02& 'ROUND #LUTTER IN A -OVING 2ADAR  7HEN THE RADAR IS MOVING WITH A VELOCITY  6 2  THE CLUTTER IS SPREAD OVER THE FREQUENCY DOMAIN AS ILLUSTRATED IN &IGURE  FOR THE  SPECIAL CASE OF HORIZONTAL MOTION 4HE FOLDOVER IN RANGE AND DOPPLER IS ILLUSTRATED  IN &IGURE  FOR A MEDIUM 
 Inshipborne radar ithasbecome evident that forcertain applications athird axis should beadded toensure atrue and undistorted display ofthe radar signals. The nature ofthese dis- tortions will beclear from the following considerations. When aship and itstwo-axis antenna mount arerolled totheright and theelevation axis momentarily setathwartship sothat theantenna islooking for- ward, iftheelevation angle ofthe beam isvaried thebeam thereupon describes onthe sky the arcofa great circle which isnot vertical but which isinclined toward the right. 
 Uslengh: "Electromagnetic and Acoustic Scattering by  Simple Shapes." North-Holland Publishing Co., Amsterdam, and John Wiley & Sons, Inc., New York,  1969.  19. Ruck, G. 
 POWER VOLTAGE SUPPLY  BUT THESE VOLTAGES NEED NOT BE AS WELL REGULATED AS THE MAIN 
 These point targets typ- ically have a radar cross section of 103 to 104 m2. Figure 15.1 Ia shows a PPI display of all clutter observed with a surveillance radar with a 1.3° by 2-fxs resolution cell in the mountainous region of Lakehead, Ontario, Canada. (The PPI range is set for 30 nmi.) Clutter that exceeds the minimum- discernible signal (MDS) level of the radar by 60 dB is shown in Fig. 
 12. Ridenour, L. N.: "Radar System Engineering," McGraw-Hill Book Co., New York, 1947. 
 The phase-detection AMTI method allows slowly moving t'argets to be  detected when the aircraft velocity is large.  Ground relief, such as due to hills or mountains, stands out on SAR imagery because of  the shadows they form, especially when viewed at low grazing angles. Shadows help emphasize  topographic and geologic features that permit a trained interpreter to learn much about the  nature of the terrain. 
 1947.  4. Strallon. 
 BAND  PHASED ARRAY  SOLID 
 Ê  1// 
 2, p. 2, June, 1954.  2. 
 This conclusion is further warranted by the statistical nature of the "noise" which is usually the limiting factor in the signal detection process. In other words, even if all the envi- ronmental factors were precisely known, a range prediction would not be likely to be verified exactly by the result of a single experiment. A statistical prediction refers to the average result of many trials. 
 In general, both papers conclude that the cross-beam resolution possible is inherently limited by the decorrelation time of the targets due to their turbulent motion. Consequently, SAR offers little advantage over real aperture systems for meteorological applications from aircraft. However, space-borne systems can effectively use SAR because of the high speed of the orbiting spacecraft. 
 H. F. Smith, “Bathymetric estimation,” in Satellite Altimetry and Earth  Sciences , L.-L. 
 In recent years, integration methods based on digital circuitry have become practical and are now perhaps the method of choice in many if not most cases. The benefit of integration is a function of the number of pulses integrated. If integration is performed in the predetection stages of a receiver, ideally the ad- dition of M equal-amplitude phase-coherent signal pulses will result in an output (integrated) pulse of voltage M times the single-pulse voltage. 
 4, pp. 736–739, November 1982. 44. 
 They also lend themselves toagreater efficiency, not only because thecircuit initself ismore efficient, but because the overhead— auxiliary circuits, cathode power, etc.—is less. Insize and weight, fora given sebofoutput conditions, the advantage isdecidedly with the line- type pulser. For airborne pulsers, these advantages inefficiency, size, and weight outweigh any advantage offlexibility yorpulse shape which the hard-tube pulser may offer. 
 Davies. D. E. 
 xvi - Operational use of HF over-the-horizon radar - Improved methods for detecting moving targets in clutter, including space-time adaptive processing - Operational use of inverse synthetic aperture radar for target recognition - Interferometric synthetic aperture radar, or InSAR, to obtain the height of a resolved scatterer or to detect moving ground targets as well as provide a SAR image of a scene - High precision space-based altimeters, with accuracy of a few centimeters, to measure the Earth’s geoid- Ultrawideband radar for ground penetrating and similar applications- Improved high power, wide bandwidth klystron power sources based on clustered cavity resonators, as well as the multiple-beam klystron - The appearance of wide bandgap semiconductors that allow better performance because of high power and high operating temperatures - The availability of high-power millimeter-wave generators based on the gyroklystron- Nonlinear FM pulse compression with low sidelobe levels- The replacement, by the computer, of the operator as information extractor and decision maker The above are not listed in any particular order, nor should they be considered a complete enumeration of radar developments since the appearance of the previous  edition.  There were also some radar topics  inprevious editions of the Radar Handbook  that are of lesser interest and so were not included in this edition. The chapter authors, who are experts in their particular field, were told to consider the reader of their chapter as being knowledgeable in the general subject of radar and even an expert in some other particular area of radar, but not necessarily knowledgeable about the subject of the particular chapter the author was writing. 
 iswhat shouldguidcthemilitary systcms planncr andtheradarsystems dcsigner. Thisbroader concept, however. isnotappropriate fordiscussion here.Instead. 
 POWER LAW  AS RANGE INCREASES 4HIS HAS THE EFFECT OF NOT PERMITTING DETECTION OF TARGETS WITH APPARENT RADAR CROSS SEC 
 0.51 V and H 10 1–6 (1976)  −3.6   . −0.41 V and H 10 6–17  −6.5   .   0.07 * After R. 
 Corrr.. Kt.corr1, vol. 7, pt. 
 A. Farina and E. Hanle, “Position accuracy in netted monostatic and bistatic radar,” IEEE Trans .,  vol. 
 I3 Inprinciple, thetraveling-wave tubeshouldbecapable ofaslargeapoweroutputasthe klystron. Thecathode, RFinteraction region,andthecollector areallseparate andeachcan hedesigned toperform theirrequired functions independently oftheothers.Inpractice, however. itisfoundthattherearelimitations tohighpower.Thenecessity forattenuation or seversinthestructure, asmentioned above,tendstomakethetraveling-wave tubelessefficient thantheklystron. 
 The introduction of Metox was a serious setback for ASV operation and shipping losses started to increase again. A possible mitigation strategy proposed for submarines detected in the forward beam was to immediately reduce height to about 100 ft and approach the submarine in the lower part of the multipathinterference lobe. The strength of the signal received by a warning receiver from a radar at a height hshould vary as hat a given range, in the same manner as the suggested variation with height for radar returns. 
 NOISE DENSITY IS OB TAINED BY DIVIDING THIS  POWER BY THE 02& BANDWIDTH 4HE MAXIMUM GATED PHASE NOISE FLOOR IS SET TO BE  D" BELOW THE THERMAL NOISE FLOOR FOR AT MOST A  D" SENSITIVITY LOSS 4HE #7 PHASE NOISE FLOOR IS THEN OBTAINED BY MULTIPLYING BY THE 02& TO TRANSMIT BANDWIDTH RATIO 4!",%  #7 0HASE .OISE $ENSITY &LOOR #ALCULATION 0ARAMETER 6ALUE ;D"= 5NITS #OMMENT 4HERMAL .OISE 0OWER AT !$ 
 Although airborne centimetric radar has great possi-  bilities in peacetime civil aviation, it must be remem-  bered that H2S, ASV, and other systems, which were  among the most spectacular developments of war, are  limited for civilian use. Military-type H2S 1s too com-  plex, too heavy, and too costly for civilian use. At first  sight it appears to offer the ideal radio aid te navigation,  for it is a continuously running ‘television’ map of the  ground, being a direct replacement for contact flying. 
  
 Peak data rates are on the order  of 360 kbit/s. All modes operate at Ku band (13.8 GHz). In its most favorable lower  altitude imaging geometry, ground range and azimuth resolutions are on the order of  0.5 km, at 4 looks. 
 Thedoppler iszerowhenthetrajectory isperpendicular to theradarlineofsight(0=90°). Thetypeofradarwhichemploys acontinuous transmission, eithermodulated orunmod­ ulated.hashadwideapplication. Historically, theearlyradarexperimenters worked almost exclusively withcontinuous ratherthanpulsedtransmissions (Sec.1.5).Twoofthemore 10,000 1,000 Radarfrequency, MHz1,000--. 
 itsfUllction maybeperformed byastableclockorreference oscillator synchronized tothetransmitter. Itwillbeassumed, therefore. thataknowledge ofthetrans­ mittedsignalisalwaysavailable atthereceiver, whether fromthedirectsignalorfroma suitahlc reference clock. 
 PULSE DIFFERENTIAL GAIN IS  $$'D' DD' D4P     QQ QQQ QQ       &)'52%  !NTENNA SCANNING EFFECTS  A  AS SEEN BY THE ANTENNA RADIATION PATTERN  DUE TO THE APPARENT  CHANGE IN AZIMUTH OF THE SCATTERER  QQ Q 
           
 YEAR HISTORY OF SCATTEROMET 
 SENSITIVE  RADARS IS CONDITIONAL UPON THE VELOCITY OF THEIR HOST PLATFORM 4HE VELOCITY OF A SPACE 
 &  !PRIL   # # &REENY  h4ARGET SUPPORT PARAMETERS ASSOCIATED WITH RADAR REFLECTIVITY MEASUREMENTS v  0ROC  )%%%  VOL   PP n  !UGUST   % & +NOTT ET AL  2EF   P  7 ( %MERSON  h%LECTROMAGNETIC WAVE ABSORBERS AND ANECHOIC CHAMBERS THROUGH THE YEARS v  )%%% 4RANS  VOL !0 
 The problem isshown inmore detail inFig. 10.13. Consider an electron atpoint Aattheinstant forwhich thefields areasshown. 
 40-45, IEEE Publication  77CM 1250-0 AES.  136. Sangiolo, J. 
 Uniitations of millimeter waves. The application of millimeter wavelengths has been limikd  hy the availability of suitable components. Transmitter powers are low, receiver noise figures  are high, transmission lines lossy. 
 SUMMINGvCOHERENTLY ADDING  N ADJACENT RETURNS 4HE CON 
 Kelleher, K. S.. and H. 
 Randall, of Birmingham, produced a magnetron,  ‘ which was the first high-power generator of centimetre-  length waves, The magnetron remains the very heart  . 28 HOW RADAR WORKS  of much modern radar transmitting equipment. This  new tool was eagerly seized upon by radar researchers,  the only setback (for this was during wartime) being that  caused by some operational heads of the Fighting  Services, who recognized the vital need for the mag-  netron, but refused to allow aircraft carrying the new  valve to fly over enemy territory, lest one complete  magnetron be disclosed in a crashed aircraft. 
 The scanning fan-heam search radar can also provide tracking information to determine  the path of the target and rrec.lict its future position. Each time the radar beam scans past the  target. its coordinates arc obtained. 
 From this range profile, an estimate of the target size can be made.  The profile obtained by the radar is the projection in the direction of propagation. A complete  "image" of the target would require multiple looks from different directions. 
 , 
 6.8. The  tuning piston can be positioned mechanically from outside the vacuum by means of a vacuum  bellows. This tuning mechanism may be adapted to provide narrowband frequency agility at a  rapid tuning rate for frequency-agile radar. 
 The true scattering mechanisms of the targets can be restored well by the RCS curves after denoising. Thus, the aspect entropy values are close to the true value. In the experimental results, the aspect entropy values of dihedral are around 0.69 and the aspect entropy values of trihedral is around 0.79. 
 22-28, February, 1977.  46. Dilorenzo, J. 
 Any use is subject to the Terms of Use as given at the website. Meteorological Radar.  METEOROLOGICAL RADAR  19.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 Figure 19.3 shows an example of radar reflectivity data from the Frederic, Oklahoma,  radar as a line of intense thunderstorms and associated rainfall pass through the cover - age area. The processing techniques used to generate the various weather images and  products are discussed later in this chapter. 
 When tighter channel tracking is  required, such as for sidelobe canceler or digital beamforming applications, FIR  filter equalization can be used to correct for frequency dependent variations across  the receiver bandwidth. FIR filter equalization can be performed either subse - quent to the FIR filtering used to generate I/Q data or combined with these filters.  It should be noted that to correct for frequency and phase variation across the  receiver bandwidth requires FIR filters with complex coefficients, applied equally  to I and Q data. 
 The equation for the power spectral density of any one segment as a func - tion of frequency is  S f Sf ff f f ( )= ⋅   ≤ ≤1 11 2α  (2.42) Here f1 and f2 are the start and end frequencies of the segment, respectively;   S1 (Hz–1) is the phase noise spectral density relative to the carrier at the beginning of  the segment and a  is the slope of the segment in log10-units per decade. Note that the FIGURE 2.76  Single-sideband phase-noise spectral density of a microwave oscillator and the effective  noise density FIGURE 2.77  Adjustments, based on system parameters (see text), to the phase noise of a microwave  oscillator ch02.indd   69 12/20/07   1:45:42 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Although theairborne refractometer maygiveexcellent dataonthevariation oftheindexof refraction. itisnotalwayssuitable formanyapplications sinceitrequires anaircraftor helicopter. Theindexofrefraction profilecanalsobedetermined bymeasuring thepressure, temper­ ature.andhumidity asafunction ofaltitude andusingEq.(12.9)tocompute therefrac­ tivity.Theradiosonde isaballoon-borne package ofinstruments forobtaining such measurements.40Thedataistelemetered backtotheground.Onedrawback oftheradiosonde isthatitisgenerally aslow-response instrument, andisnotalwaysabletodetectwith surtlcient accuracy thesignificant refractive indexgradients neededforobtaining anaccurate description oftheraypaths. 
 ch20.indd   44 12/20/07   1:16:53 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 
 The simple helix was used as the slow-wave structure in the early TWTs and is still  preferred in traveling-wave tubes at power levels up to a few kilowatts. It is capable of wider  bandwidth than other slow-wave structures, but its power limitations do not make it suitable  for most high-power radar applications. A modification of the helix known as the ring-bar  circuit has been used in TWTs to achieve higher power and efficiencies between 35 and 50  percent."*12 The Raytheon QKW-1671A, which utilizes a ring-bar circuit, has a peak power  of 160 kW, a duty cycle of 0.036,"p'ulse width of 70 ps, gain of 45 dB, and a 200 MHz band-  width at L band. 
 26.9 AREPS RADAR DISPLAYS By default, the results of the propagation model calculations are shown in terms appro - priate for a tactical radar operator, i.e., a height versus range display of radar probability  of detection as a percentage, as illustrated in Figure 26.15. This display is referred to  as a tactical decision aid because it will allow the radar operator to make some sort of  tactical decision. For example, superimposed on this tactical decision aid is the flight  profile of a target missile (the solid line sloping downward to the origin from right to  left). 
         &)'52%  $IGITAL DOWNCONVERSION SPECTRA                      .   2!$!2 2%#%)6%23   È°{Î (ILBERT 4RANSFORMER  !N ALTERNATIVE DIGITAL RECEIVER ARCHITECTURE IS SHOWN IN  &IGURE  WITH THE RELEVANT SIGNAL  SPECTRA SHOWN IN &IGURE  4HE !$ CONVERTER  OUTPUT SIGNAL  XN  IS PROCESSED USING A (ILBERT TRANSFORMER COMPRISING &)2 FILTERS  HN  AND HN   WHERE THE FREQUENCY RESPONSES ARE GIVEN BY    \   \ \   \((  VVyy   \\VV 
 S. D. Solomon, D. 
 The data was plotted as a ratio of bistatic to monostatic RCS, VD/<JM. The measurements match KeIFs model: of the 27 data points, 24 show bistatic RCS lower than monostatic RCS. The bistatic RCS reduction starts at about (3 = 5° and trends downward to VB!VM = -15 dB at p = 50°. 
 Generally speaking, most me- teorological doppler radars are operated in a single mode, compromising the ra- dar's ability to unambiguously resolve either range or velocity. More recent designs, however, may use a dual pulse repetition period38 (PRT) to resolve both range and velocity. Another approach39 is to employ a transmitted-pulse se- quence with random phases from pulse to pulse. 
 ______ ...L ___ _  a a+b X  (al  0  ( C) 0 Xo  ( b)  (d) X  w  f<igure 2.2 Examples of probability-density functions. (a) Umform; (b) Gaussian; (c) Rayleigh (voltage);  (d) Rayleigh (power) or exponential. 22 INTRODUCTION TO RADAR SYSTEMS  where k is a constant. 
 SENSITIVE MODEL OF ATMOSPHERIC NOISE AND ITS APPLICATION TO THE  ANALYSIS OF (& RECEIVING ANTENNAS v 2ADIO 3CIENCE  VOL   PP n    9U ) !BRAMOVICH  . + 3PENCER  AND 3 * !NDERSON  h%XPERIMENTAL STUDY OF THE SPATIAL  DYNAMICS OF ENVIRONMENTAL NOISE FOR A SURFACE 
  
 FORMANCE CHARACTERISTICS -IXER 3PURIOUS 
 Table 7.1. Radiation-pattern characteristics produced by various aperture distributions  1 = wavelength; a = aperture width  Type of distribution, I z I < 1  Uniform; A(z) = 1  Cosine; A(z) = cos" (nz/2):  It = 0  11= 1  n=2  n=3  n = 4  Parabolic; A(z) = 1 - (1 - A)z2  A = 1.0  A = 0.8  A = 0.5  A = 0  Triangular; A(z) = 1 - 1 z /  Circular; A(z) = Jz2  cosine-squared plus pedestal;  0.33 + 0.66 cos2(nz/2)  0.08 + 0.92 cos2(nz/2), Hamming Relative  gain Half-power  beamwidth,  deg Intensity of first sidelobe,  dB below maximum ~ntenslty  (7.17)232INTRODUCTION TORADAR SYSTEMS Thenormalized radiation patternis E(¢)=~[sin(IjJ+nil)+sin(IjJ-nI2)] 4IjJ+nl2 IjJ-nl2 whereIjJ=n(all)sin¢.InFig.7.3thegainsofbothpatterns arenormalized. However, the maximum gainofthepatternresulting fromthecosinedistribution is0.9dBlessthanthegain ofauniform distribution. 
 Knott, “A progression of high-frequency RCS prediction techniques,” Proc. IEEE , vol. 73,  pp. 
 A frequency-scan radar can radiate undesirable grating lohes, just as can any other array,  if the electrical spacing between elements is too large. From Eq. (8.IOh), the relationship  between the angle 09 at which the first grating lobe appears, and the angle 00 to which th.:! main  beam is steered, is given by  !sin of/ -sin Oo I )../d  If we assume that the grating lobe can be tolerated if it is located at ± 90°, then  j l + sin 00 I ~ )../d (8.20)  (8.21)  The limiting scan angle for the appearance of grating lobes is shown by the dashed curves in  Fig. 
 The AGC, required for gain normalization, is made faster than the bandwidth of the filters and thus acts as an instantaneous AGC. Its dynamic range has to cope only with target signal variations. The normalized monopulse error signals are then demultiplexed and used for closing the guidance loops. 
 Apotentiometer isalmost invariably used asthe azimuth data transmitter for anelectrostatic tube. Itmay drive the deflecting plates directly, inwhich case itmust have two brushes delivering peak potentials offrom one totwo hundred volts. Alternatively, apush-pull direct-coupled amplifier isinserted. 
 Also, an interferometric pair has been processed and the interference fringes have been extracted to show the good performance and phase stability of the proposed technique. 2. Materials and Methods The proposed approach aims to show that the information needed to obtain the focused image can be extracted from the raw data itself when a point scatterer (either natural or manmade) is present in the scene. 
 Purduski114  © IEEE 1980 ) ch16.indd   33 12/19/07   4:56:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 When f = 180°,  b = |qs − qi|. In the monostatic case,   f  = 180°, b = 0, and qs = qi. In-plane  data is shown in bold type on the table. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.68  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18  95. 
 116. Scllacfer. (i. 
    
 F:0t, t, t;t; C2 c, .-— y;(2)Plate1 l-rl_rLB+ (3)Grid2 --~m-+~~f I(4) Plate 2 —rul_rB+ FIG. 13.13.—Eccles-Jordan multivibrator. Aside from the squaring amplifier, which will not bediscussed here, there arethree principal forms ofrectangular-wave generators. 
 When the phase of the first element is taken as the reference, the phase shifts  required in the succeeding elements are 4, 24, 34, . , (N 5 I)$.  The maximum phase change required of each phase shifter in the parallel-fed array is  many times 2n radians. 
 The duplexers described above using passive receiver protec-  tors have recovery times from a fraction of a microsecond to several tens of microseconds. By  employing the principle of multipacting, a recovery time as short as 5 ns is pos~ible.~~*~~ A  multipact& is a vacuum tube which contains surfaces capable of a high yield of secondary  emission upon impact by an electron.   he secondary emission surfaces are biased with a d-c  potential. 
 6. Barlow, E. J.: Doppler Radar, Proc. 
 WISE COMBINING OF THESE IMAGES WITH THE PROPER RELATIVE COMPLEX WEIGHTING TO NULL THE CLUTTER CAN BE CONSIDERED AS AN )N3!2  PROCESS /N THE OTHER HAND  TO AVOID CONFUSION WITH THE TYPE OF INTERFEROMETRIC 3!2  THAT IS USED FOR TARGET HEIGHT MEASUREMENT  THE *OINT 34!23 TEAM TYPICALLY REFERS TO THEIR PROCESS AS h#LUTTER 3UPPRESSION )NTERFEROMETRYv OR SIMPLY h#3)v p "ARBAROSSA AND &ARINA SHOW THAT  BY USING MULTIPLE SUBAPERTURES  DETECTION AND  REPOSITIONING OF MOVING TARGETS CAN BE CONSIDERABLY IMPROVED  IN AN EXTENSION OF THE REAL 
 (21.15) is less than or equal to the synthetic antenna length for the unfocused case as given by Eq. (21.12), only a limited improvement in resolution is achievable for the fo- cused case. However, if a resolution finer than that given by Eq. 
 TIONAL  SUCH AS THOSE PRODUCED BY OTHER RADARS OR CLUTTER  MAY SIGNIFICANTLY DEGRADE THE . £Î°xn  2!$!2 (!.$"//+  PERFORMANCE OF STATIC 
 Ideally,  STC should make the average clutter power always equal to the noise power. Thus its range  variation should be identical to the clutter-power range variation. It has been suggested that  STC for a civil-marine radar have a gain proportional to R -3 out to a range of 8h0 hw /3J.., after  which it is proportional to R-7, where R = range, h0 = radar antenna height, hw = wave  height from peak to trough, and J.. 
 In this cutaway sketch, four  polarization sensitive parabolic reflectors surround a rotating twist-reflector mirror. For  convenience, tb.e entire structure is shown enclosed within a radome. Fixed feeds illuminate  each reflector. 
 PULSE  WIDE 
 The LNAs are wideband devices, vulnerable to interference over  the entire radar operating band and often outside this band; although off-frequency  interference is filtered in subsequent stages of the receiver, strong interference signals  can cause clutter returns in the LNA to be distorted, degrading the effectiveness of  doppler filtering and creating false alarms. This phenomenon is difficult to isolate as  the cause of false alarms in such radars owing to the nonrepetitive character of many  ch06.indd   7 12/17/07   2:03:00 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The maximum phase error acceptable for SAR image is π/4[21]. If the phase error exceeds π/4, the SAR image will severely defocus (when the phase error is less than π/4, this error is too small for SAR imaging to be ignored). Therefore, the condition for severe defocusing of the ArcSAR imaging result on the reference plane is: Δpmax≥π/4 4πfc c·ΔRmax≥π/4 ΔRmax≥λ 16(16) whereλrepresents the wavelength. 
 20–25,  1962. 103. M. 
 FED PARABOLAS OR REFLECTARRAYS BECAUSE OF ITS SIZE ! FOCAL 
 InFig. 10.17 thecircles about points Aand Brepresent theVSWR =1.5 circle when displaced different distances from the center ofthe diagram. The load points Aand B,with their associated variations inload in the above example, are especially simple cases. 
 S. Noblit, “Reliability without redundancy from a radar monopulse receiver,” Microwaves ,   pp. 56–60, December 1967. 
 Normally the azi muth values are in particular dissatisfactory for large ranges, as they arise for  Earth exploration by Radar from satellites.  With a range of 300 km and a half -power ban d- width of 1°, the resolution is ∆z = 5,2 km.   10.2 Procedures for Improving the Resolution   10.2.1  Range Resolution with Pulse Compression   The range resolution can be improved with shorter pulse duration and/or a larger FM ban d- width. 
 THE 
 E. F. Knott, Radar Cross Section Measurements , New York: Van Nostrand Reinhold, 1993,  pp. 
 8.2 Comparison of angular estimates with the Cramer-Rao lower bound, a is the standard deviation of the estimation error, and N is the number of pulses within the 3-dB beamwidth, which is v. The S/N is the value at the center of the beam. (Copyright 1956, IEEE; after Ref. 
 This calculation will now include the effect of a target doppler  ch02.indd   21 12/20/07   1:44:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 Khattatov, M. Murphy, M. Gnedin, T. 
 ch19.indd   3 12/20/07   5:37:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 
 Theimaging oftheearth'ssurface bySARtoprovide amaplike displaycanbeappliedtomilitary reconnaissance, measurement ofseastateandoceanwave conditions. geological andmineral explorations, andotherremotesensingapplications.98 Theresolution inthecross-range dimension ofaconventional antenna is (14.1) whereRistherangeandOnisthebeamwidth. Thenarrower thebeamwidth, thebetterthe resolution (smaller /5e,).Thereisalimit,however, totheminimum beamwidth ofapractical microwave antenna because ofthedifficulty ofachieving andmaintaining thenecessary mechanical andelectrical tolerances (Secs.7.8and8.8).Iftheantenna beamwidth werea!> smallasO.r,the rcsolution ()c,atarangeof100kmwouldbeabout350m,whichisfarlarger thanthefraction ofameterresolution possible intherangecoordinate withtheuseof pulse-compression radar.S/\Rpermitstheattainment ofhighresolution byusingthemotion ofthevehicletogenerate thcantcnna aperture sequentially ratherthansimultaneollsly aswitha conventional arrayantenna. 
 Austin, A. Benedetti, C. Mitrescu, and the  CloudSat Science Team, “The CloudSat mission and the A-train: a new dimension of space-based  observations of clouds and precipitation,” Bull. 
 Keeler and L. J. Griffiths, “Acoustic doppler extraction by adaptive linear prediction filter - ing,” J. 
 An example of such a facility is the dynamic radar cross-section range of the U.S.  Naval Research Lab~ratory.~' Radars at L, S, C and X bands illuminate the aircraft target in  flight. The radar track data is used to establish the aspect angle of the target with respect to the  radar. 
 SQUARE METER OR GREATER  4ECHNIQUES  AND  ARE USED WHEN THE DESIRED TARGETS MAY HAVE RADAR CROSS SECTIONS SIMILAR TO  OR SMALLER THAN  A BIRD 4ECHNIQUE  34# IS THE TRADITIONAL METHOD OF SUPPRESSING BIRDS AND INSECTS IN A  RADAR WITH AN UNAMBIGUOUS RANGE  02& A 02& LOW ENOUGH SO THAT T HE RANGE TO TARGETS  AND CLUTTER IS UNAMBIGUOUS  34# DECREASES THE SENSITIVITY OF THE RADAR AT SHORT RANGE AND THEN INCREASES SENSITIVITY  USUALLY USING A FOURTH 
 E., I. S. Reed, and P. 
 A. Scholtz: Generalized Barker Sequences, IEEE Trans., vol. IT-Il, pp. 
 AP-9, pp. 1715–1727,  October 1960. 44. 
 The returned echo signal is collected by the radar antenna and amplified by the receiver. If the output of the radar receiver is sufficiently large, detection of a target is said to occur. A radar generally determines the location of a target in range and angle, but the echo signal also can provide information about the nature of the target. 
 Synchronizer .......... Synchronizer power supply.,,., Scanner *....,.. Indicator and visor.....,..,,.. 
 For a radar  height of 30 m, a target height of 100 m and a range of 10 km, the range-resolution must be  0.6 m, corresponding to a pulse width of 4 ns. This is a much shorter pulse than is commonly  employed in radar. Although the required range-resolutions for a ground-based radar are  achievable in principle, it is usuaHy not applicaple in practice. 
 POLE DATA COLLECTION  THE TELEMETRY TRANSFERRED THE ACCUMULATED DATA TO ONE OF THE THREE $EEP 3PACE .ETWORK $3.  RECEIVING STATIONS  SO THAT  IN CONSE 
 Shrader Shrader Associates, Inc. Vilhelm Gregers-Hansen Naval Research Laboratory 2.1 PREFACE This chapter addresses surface-based radars; e.g., radars sited on land or installed  onboard ships. For airborne radar, rapid platform motion has a significant effect on  design and performance as discussed in Chapters 3, 4, and 5 of this Handbook. 
 The  altimeter contains an on-board calibrate mode, currently  invoked twice a day, that is designed to track long-term  drifts. In the discussion that follows, only the essential  aspects of the processing steps have been included for  clarity.  Waveform Sample Gain Correction  The altimeter on-board tracker operates on a set of  60 waveform samples that are the power spectrum out­ puts of a digital filter bank, as discussed previously. 
   ,&- WITH n D" 4AYLOR WEIGHTING    
 An axial magnetic field is provided to maintain the  electron-beam focus, just as in the klystron. A shadow grid to pulse-modulate the beam can  also be included. After delivering their d-c energy to the RF field, the electrons are removed by  the collector electrode. 
 Figure 17.13 a illustrates a perspective view. Because Rg  H, the isodop ( y1 – axis)  makes an angle qsq with the y-axis. The image center is a distance S ≅ Rg cos qsq from  the x-axis, where Rg = ground range. 
 IOR OF CLUTTER SIGNALS TRACE ESSENTIALLY FROM THE WORK PURSUED DURING 7ORLD 7AR )) AND DESCRIBED IN THE WELL 
   PP n  . 
 CALLED WIZARDS IN ADDITION TO THE GENERALIZED '/'4$ 
 BASED DEPLOYABLE , 
 However, it may be  shown that the average beat frequency measured over a modulation cycle, when substituted  into Eq. (3.1 1) yields the correct value of target range. Any reasonable-shape modulation  waveform can be used tb measure the range, provided the average beat frequency is  meas~red.~'.~~ If  he target is in motion and the beat signal contains a component due to the -  doppler frequency shift, the range frequency can be extracted, as before, if the average  frequency is measured. 
 11.1);but since theprobe does notdiffer much from anopen circuit, theload forthelocal oscillator isstill agood match. The voltage atthe probe isthe same asthat atthedisk. Itisnecessary tohave theprobe spaced aquarter wavelength onthe signal line from the effective plane ofthecoupling loop. 
 ilarrington, J. V., and T. F. 
 The frequency response curve hasitsmaximum attheresonant frequency ofthecrystal and falls tozero atzero frequency. Thus itisnotpossible totransmit video pulses directly through thedelay line without distortion. Instead, the pulses are used tomodulate a carrier whose frequency isthat forwhich the crystal isresonant. 
 Following the A/D is typically a delay-line clutter can- celer and doppler filter bank for main-beam clutter rejection and coherent inte- gration. The filter bank is usually realized by using the fast Fourier transform . FIG. 
 LYZED IN THE LITERATURE FOR MANY DIFFERENT CONDITIONS !N ANALYSIS OF THE CLUTTER MAP LOSS FOR SINGLE 
 583-589, November, 1976.  56. Goggins, W. 
 Briggs, “Target detection by marine radar,” Institution of Electrical Engineers (now the  Institution of Engineering and Technology), London, 2004.  9. “The international convention for the safety of life at sea (SOLAS), 1974,” International Maritime  Organization, London, as amended. 
 FICATION ON RECEIVE $IODE PHASE SHIFTERS ARE  THEREFORE  QUITE PERMISSIBLE EVEN WITH MANY BITS EG      OR  BITS FOR LOW SIDELOBES  6ARIATIONS IN INSERTION LOSS MAY BE COMPENSATED FOR DYNAMICALLY WITH THE GAIN ADJUSTMENT 4HE CIRCULATOR AT THE HIGH 
 Rawer, S. Ramakrishnan, and D. Bilitza, “International reference ionosphere 1978,”  International Union of Radio Science, URSI Special Report, pp. 
 This isthesole adjustment. The local-oscillator input fitting contains aresistor disk which ter- minates the 50-ohm cable. Since the probe ishalf awavelength away from the disk, the load atthe probe will beinparallel with the disk (Sec. 
 As such, this imaginary sphere would have to expand and contract with changing target orientation to represent the amplitude fluctuations displayed by most objects. The limiting process in Eq. (11.1) is not always an absolute requirement. 
 SCATTER FROM THE SEA SURFACE IN THE ABSENCE OF WIND 
 In general, modern commercial instrumentation is vastly superior to the ear- lier cavity bridges for making routine measurements on low-power sources. It can measure phase noise very close to the carrier if the servo is tailored to force the two sources to track in the mean, without effectively locking them together, at the offset frequency of interest. By knowing the servo's characteristics, the instrumentation can adjust the data to reflect the phase noise actually present. 
 Polar plots of a,/a0 for various values of //J... arc shown in  Fig. 2.15. 
 SIGNAL OUTPUT IS DETECTED AND PROVIDES THE VIDEO INPUT TO THE RANGE TRACKER 4HE RANGE TRACKER MEASURES AND TRACKS THE TIME OF ARRIVAL OF THE DESIRED TARGET ECHO AND PROVIDES GATE PULSES THAT TURN ON THE RADAR RECEIVER CHANNELS ONLY DURING THE BRIEF PERIOD WHEN THE DESIRED ECHO IS EXPECTED 4HE GATED VIDEO IS USED TO GENERATE THE DC  &)'52%   -ICROWAVE 
 McGraw-Hili BookCo.,NewYork,1970. 83.Hill,R.T.:PhasedArrayFeedSystems, ASurvey," PhasedArrayAntennas, Proceedings ofthe197() PhasedArrayAntenna Symposium," A.A.OlinerandG.H.Knittel(eds.),ArtechHouse,Dedham. Mass.,1972,pp.197-211. 
 Olson.’ 16.17. The Receiver.—Two types ofreceiver characteristic have been discussed inSec. 168. 
 THE 
 Torok, N. Gordner-Kalani, M. Batista-Carver, and T. 
 HORIZON RADAR v  2ADIO 3CIENCE  VOL   PP n     ' & %ARL  h2ECEIVING SYSTEM LINEARITY REQUIREMENTS FOR (& RADAR v  )%%% 4RANS )NSTRUM -EAS   VOL   PP n    ' & %ARL  0 # +ERR  AND 0 - 2OBERTS  h/4( RADAR RECEIVING SYSTEM DESIGN USING SYNOPTIC  (& ENVIRONMENTAL DATABASE v  0ROC TH )NT #ONF (& 2ADIO 3YSTEMS AND 4ECHNIQUES   *ULY    PP n  3 * !NDERSON  h3IMULATION AND MODELING FOR THE *INDALEE OVER 
 POWER KLYSTRONS FOR THE NEXT LINEAR COLLIDER v  0ROC )%%%   VOL   PP n  -AY    2 ( !BRAMS  " ,EVUSH  ! ! -ONDELLI  AND 2 + 0ARKER  h6ACUUM ELECTRONICS FOR THE ST  CENTURY v )%%% -ICROWAVE -AGAZINE  PP n  3EPTEMBER    ' 3 .USINOVICH  " ,EVUSH  AND $ !BE h! REVIEW OF THE DEVELOPMENT OF MULTIPLE 
 The IF was 31 Mc/s with a bandwidth of about 2 Mc/s. The receivers of the Pye design used an anode bend second detector, giving a negative output signal, while the Cole designed receivers used a diode second detector, giving a positive output. This meant that different indicating units were required. 
 SOR AND CONTAINED WITHIN A SEALED ENCLOSURE  A BATTERY AND CONTROL PROCESSOR  AND DIS 
 CENTERED OVALS REFER TO 4ABLE   A HITCHHIKER CAN OPERATE WITH RANGE 
 Tuner life is no . 204 INTRODUCTION TO RADAR SYSTEMS  problem, but the tuner increases the cavity capacitance and thus decreases the cavity im­ pedance so that there is reduced bandwidth at the low-frequency end of the tuning range.  Tuning ranges of 10 to 15 percent can be obtained without a compromise in impedance by  using a sliding-contact movable cavity wall, but at the expense of increased mechanical  complexity. 
 The difference in signal-to-no~se  ratio might be from 2 to 4 dB. For the same size aperture, the beamwidth of a conical-scan  radar will be slightly greater than that of the monopulse because its feed is offset from the  foc11s.  The tracking accuracy of a monopulse radar is superior to that of the conical-scan radar  because of the absence of target amplitude-fluctuations and because of its greater s~gnal-to-  noise ratio. 
 Any use is subject to the Terms of Use as given at the website. Radar Receivers.  RADAR RECEIVERS  6.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 DC Offset.  Small signals and receiver noise can be distorted by an offset in  the mean value of the A/D converter output unless the doppler filter suppresses this  component. 
 FINDING RADARS USUALLY DETERMINE HEIGHT FROM ENERGY PATH ASSUMPTIONS  WITHIN A NORMAL ENVIRONMENT .ONSTANDARD REFRACTIVE CONDITIONS AS DISCUSSED EARLIER  WILL CAUSE THE ENERGYS PATH TO DEVIATE FROM THESE ASSUMPTIONS  RESULTING IN ERRORS IN  ALTITUDE CALCULATIONS &IGURE  SHOWS THE DOWNWARD DEVIATED PATH ASSOCIATED WITH A SURFACE DUCTING CONDITION COMPARED TO THE PATH UNDER NORMAL CONDITIONS )T CAN BE SEEN THAT ACTUAL ALTITUDE OF THE RADAR TARGET IS LOWER THAN CALCULATED BY THE HEIGHT 
 They sliowed that  the median dctc~ctoi- gave better performance in non-Rayleigh clutter than the conventional  receiver (which can be called a mcJu1l dc~tecrot-). In this detector, the median vglue of the 11  received pulses is found and compared against a threshold. This requires that the amplitt~des  of the tl individual samples (pulses) be stored and then arranged (ranked) in order of amplitude  to find the median. 
 Therefore, the average TEC of the scene can be represented by the PolSAR TEC. Second, the derived PolSAR TEC increases along with the altitude of the magnetic ﬁeld, which can be easily explained from Equation (1). Since /angbracketleftBcosθ/angbracketrightdecreases with an increase in altitude, the derived TEC will get larger. 
 The Fortresses had been found unsuitable for operation by Bomber Command and so were released to Coastal Command. However, in common with the Wellington, Sunderland and Whitley already in service they were not long-range aircraft in the context of the Battle of the Atlantic. Then, despite the inter est in DMS.1000 the United States War Department cancelled the productio n order in favour of SCR.517B, which had been selected as the standard equipment for the United States Army Air Corps. 
 PLER 4HE FUNCTION  H IS THE COORDINATE TRANSFORM THAT RELATES THE MEASUREMENTS TO THE  STATE AT TIME  TK ACCORDING TO THE COORDINATE FRAME DESIGN CHOICES SEE 4ABLE   LATER IN  THE CHAPTER  )N ORDER TO USE THE +ALMAN FILTER   H IS APPROXIMATED AS A LINEAR FUNCTION  IN THE VICINITY OF THE PREDICTED TRACK STATE  H8 H8T T (8 8T T 8 8TKK KK    \  ;  \  =  
 ch09.indd   13 12/15/07   6:07:15 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 
 1977. X6Sakamoto. II..andP.Z.Peebles, Jr.:Conopulse Radar.IEEETrailS.vol.AES-14. 
 CAVITY KLYSTRON BOTTOM  #OURTESY OF THE )%%%                    
 TRACKING RADAR 183  The monopulse radar is the rnore complex of the two. Three separate receivers are  necessary to derive the error signal in two orthogonal angular coordinates. Only one receiver  is needed in the conical-scan radar. 
 Figure 2.12 is a plot as  a function of aspect. The cross section of the cone-sphere from the vicinity of the nose-on  direction is quite low. Scattering from any object occurs fro& discontinuities. 
 In many engineering endeavors, optimum does not mean the best since the best  might not be affordable or achievable in the required time. Optimum , as used here,  means the best under a given set of assumptions. Engineering often involves achiev - ing a near-optimum, not the optimum. 
 57, pp.  1260- 1266, July. 1969. 
 Pattern Anal. Mach. Intell. 
 But it is seldom used in reference to sea clutter. There are, then, two numbers commonly used to indicate the activity of the sea surface: a subjective sea state and a measured wind speed. Only when the wind has sufficient fetch and duration to excite a fully developed sea, can a wave height be unambiguously associated with it. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 19.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 Microburst detection, like tornado detection, is accomplished by estimating shear. 
 Regardless of the model used and the approach applied to determining the field strength, theoretical work only guides understanding. Actual earth surfaces are too complex to be described adequately in any of the models, and the effects of signals that penetrate the ground and are scattered therein are too little known to permit its evaluation. 12.4 FADINGOFGROUNDECHOES The amplitude of ground echoes received by radars on moving vehicles fluctuates widely because of variations in phase shift for return from different parts of the illuminated area. 
 Both versions of the equivalence  theorem are valid when the positions of the transmitter and receiver are interchanged,  given that the target-scattering media are reciprocal. Most media are reciprocal.  Exceptions are gyrotropic media, such as ferrite materials and the ionosphere. 
 x°Ó{  2!$!2 (!.$"//+  4HE FUSION OF THE RECOGNITION OF EACH OF THE SIGNATURES ABOVE PROVIDES EXCELLENT  NONCOOPERATIVE RECOGNITION 7EATHER  !VOIDANCE  -ANY AIRCRAFT HAVE SEPARATE WEATHER RADARS 7EATHER  AVOIDANCE IS NORMALLY INCORPORATED INTO MODERN FIGHTER RADARS 4HE NORMAL OPERATING FREQUENCY FOR A FIGHTER RADAR HAS NOT BEEN CONSIDERED OPTIMUM FOR WEATHER DETECTION AND AVOIDANCE PRIMARILY DUE TO LACK OF PENETRATION DEPTH INTO A STORM AND REDUCED  OPERATING RANGE (OWEVER  WITH COMPLEX ATMOSPHERIC ATTENUATION  COMPENSATION AND  DOPPLER METHODS  WEATHER CAN BE DETECTED WELL ENOUGH TO ALLOW WARNING AND AVOID 
 SCAN RADAR  ILLUSTRATED IN &IGURE   IS TYPICALLY A SINUSOID AMPLITUDE MODULATION OF THE RECEIVED TARGET ECHO PULSES 4HE AMPLITUDE OF THE MODULATION IS A MEASURE OF THE MAGNITUDE OF THE ANGLE ERROR  AND THE PHASE  RELATIVE TO THE SCANNING 
 IEEETrailS.•vol.AP-12. pp.781782.Novemher. 1964. 
 This is a missell  detection to the radar engineer. The setting of the threshold represents a compromise between  these two types of errors. A relatively large threshold will reduce the probability of a false  alarm, but there will be more missed detections. 
 DEPENDENT "Y THE END OF   2!$!23!4 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.64  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 The main feature of these systems is the planar phased array, which has modular  construction with distributed all-solid-state electronics, including RF power genera - tion and electronic steering in the elevation axis. 
 In radar there can be no boundaries, and in the long  run, as with the harnessing of atomic power, no secrets.  From the pioneering days of Appleton and Watson-Watt  with experiments in the ionosphere and in pure research  on the reflections of radio waves from solid bodies we  have progressed to a multitude of navigational and  directional radar devices. This multitude Combis to  . 
 At HF and Millimeter-Wave Frequencies. All the measurements described above were made at microwave frequencies between UHF (428 MHz) and Ka band (35 GHz). High-frequency (HF) radars usually operate in the frequency range between about 5 and 30 MHz, corresponding to wavelengths between 60 and 10 m, respectively. 
 Fuller- Rowell, and V . Yudin, “Advanced modeling of  the ionosphere and upper atmosphere,” Environmental Research Technologies Report , A550924,  June 2004. 47. 
 706-709, July, 1971.  73. Carpentier, M. 
 SAMPLING RADAR DIGITAL RECEIVER 
 2. In  addition to data quality checks, engineering unit con­ versions, and editing for gaps, overlaps, and out-of­ sequence data, the main thrust of the processing is the  generation of height, height-rate, attitude, sea-state, and  temperature corrections. Also, initial bias offsets, derived  from preflight testing, that are expected to change slowly,  if at all, are included in the header of each tape. 
 Inprinciple, this impedance, orsome similar quantity, might be measured onanabsolute scale, and the deviations from the normal, or no-targrt value, ascribed tothepresence ofatarget. Practically, this procedure isimpossible because thereturned signals areoften 10–9 times aslarge, onavoltage basis, asthe outgoing signals, with the result that the variations inimpedance might beofthe order ofapart in10’. Such variations can hardly bemeasured inthelabora- tory atlowfrequencies, letalone inthefield and atmicrowave frequencies. 
 Thus each value of the  index k defines a separate filter response, as indicated in Fig. 4.23, with the total response  covering the region from j'= 0 to f= 1/T =.f,. Each filter has a bandwidth of 2/NT as  measured between the first nulls. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 3.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 factors for the DPCA main-beam and the sidelobe regions in the same manner as paral - lel impedances are combined:  1 1 1 I I Isl total DPCA= +  (3.11) If the aperture distribution is used, the sidelobe effects are inherent in the analysis. 
 In this paper, both the imaging performance and scintillation effect for P-band sliding spotlight mode are studied. The theoretical analysis of scintillation effect is performed based on a reﬁned model of the two-frequency and two-position coherence function (TFTPCF). A novel scintillation simulator based on the reverse back-projection (ReBP) algorithm is proposed to generate the SAR raw data for sliding spotlight mode. 
 The surrounding reference  cells are then used to estimate the unknown parameters, and a threshold based on the  estimated density is obtained. Nonparametric detectors obtain a constant false-alarm  rate (CFAR) by ranking (ordering the samples from smallest to largest) the test sample  with the reference cells. Under the hypothesis that all the samples (test and refer - ence) are independent samples from an unknown density function, the rank of the test  sample is uniform; and consequently, a threshold that yields CFAR can be set. 
 Nosatisfactory descriptive term exists forthis auxiliary equipment, but incombination with the indicator itisknown asthe “indicating (or indicator) equipment. ”The echo signals must be amplified greatly and demodulated before being presented tothe indica- tor, usually intheform ofvideo signals. The path which they follow in this process will bespoken ofasthe“signal channel,” and theequipment involved asthe “receiver.” Onsome occasions thesystem also contains computers orother devices which aidintheultimate disposal ofthedata. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 
 Albrecht, and F. Marks, Jr., “Why Mie?,” Bull. Amer. 
 For example, suppose v=300 mph, VI=800 mph, EI=2°=&radian, e=90°, Then AU=10mph and thefluctuation is8percent.. 658 When o=Othe insteadMOVING-TARGET 1NDICA TION [SEC. 16.14 above equation forAUnolonger holds and wehave AU=@z for8=O. 
 BAND MAGNETRON THAT OPERATES AT A FIXED FREQUENCY WITHIN THE BAND FROM  TO  -(Z WITH A PEAK POWER OF  K7 AND AN EFFICIENCY OF  )T OPERATES WITH AN ANODE VOLTAGE OF  K6 AND AN ANODE CURRENT OF  AMPS 4YPICALLY  ITS PULSE  WIDTH MIGHT BE  §S WITH A DUTY CYCLE OF   4HE MANUFAC 
 CODED SIGNAL  THE ELEMENTS OF THE RECEIVER PRECEDING THE DECODER WILL NOT RESTRICT THE DYNAMIC RANGE OF A POINT TARGET AS SEVERELY AS THEY WILL FOR DISTRIBUTED CLUTTER THE TIME 
 and Terrain. Proc. IEE. 
 Mumford, W. W.: Some Technical Aspects of Microwave Radiation Hazards, Proc. I RE, vol. 
 BAND 3!2  DATA v 0ROCEEDINGS )%%% 'EOSCIENCE 2EMOTE 3ENSING 3YMPOSIUM )'!233   (AMBURG   'ERMANY  VOL     P n !LSO SEE ,- 5LANDER ET AL  h$ETECTION OF CONCEALED GROUND TARGETS IN #!2!"!3 3!2 IMAGES USING CHANGE DETECTION v  0ROCEEDINGS 30)%  VOL     P n  !LGORITHMS FOR 3YNTHETIC !PERTURE 2ADAR )MAGERY 6)   % ' :ELNIO ED     % - 7INTER  - * 3CHLANGEN  AND # 2 (ENDRIKSON  h#OMPARISONS OF TARGET DETECTION IN CLUT 
 Res. Oceans 1997 ,102, 25251–25267. [ CrossRef ] 26. 
 IEEE, vol. 73, pp. 970-996, June 1985. 
 MODULATION NOISE DENSITY IN VICINITY OF SCAN RATE  KS   CONICAL 
 Rowland, “A tutorial assessment of atmospheric height uncertainties  for high-precision satellite altimeter missions to monitor ocean currents,” IEEE Transactions  Geoscience and Remote Sensing , vol. 20, pp. 418–434, 1982. 
 Equation (2.40) may be rewritten as  The noise figure may be interpreted, therefore, as a measure of the degradation of signal-to-  noise-ratio as the signal passes through the receiver.  j Rearranging Eq. (2.417). 
 The non-Rayleigh nature of the clutter must be properly considered in the detector  design if large increases in the minimum detectable signal-to-clutter ratios are to be avoided.  Pulse width. The radar equation that applies to the detection of targets in surface clutter at low  grazing angles (Eq. 
 K. Barton, Radar , vol. 6, Frequency Agility and Diversity , Norwood, MA: Artech House,  Inc., 1977. 
 In this example, the correlated target range  has an ambiguity number of 4 (5th time around echo) on PRF 1, and an ambiguity   Unambiguous Range Interval D1 D2 D3PRF 2 PRF 3PRF 1D1, D2, D3 = Ambiguous range measurements for looks 1, 2, 3 Range correlation: M of N = 3 (of 3)Unfolded ranges= Transmit and receive blank time FIGURE 4.17  Range correlation example with 3 PRFs ch04.indd   31 12/20/07   4:53:00 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 The five narrow hyperbolic bands define the area that contributes to clutter in the selected doppler filter. The shaded intersections represent the area that contributes to the range-gate-doppler-filter cell. Each area contributes clutter power dependent on antenna gain in the direction of the area and the reflectivity of the area. 
 The  K f; c;tvitics, wliicli co~-r.csl,or~tl to tile LC rcsoriarit ci~.cuits oflowcr-frequerlcy amplifiers. are at  a~iode poteritial. I~lcctror~s are not interitionally collected by the anode as in other tubes;  instead, the electrons are removed by the collector electrode (shown on the right-hand side of  tlie diagram) after the beam Iias given up its RF energy to the output cavity. 
 Randall, and A. Zahrai, “Design and deployment of  a portable, pencil-beam, pulsed, 3-cm doppler radar,” J. Atmos. 
 TION  THE !$ CONVERTER INPUT SIGNAL NOISE BANDWIDTH MAY BE SIGNIFICANTLY LESS THAN THE  .YQUIST BANDWIDTH 4HIS IS A SIGNIFICANT FACTOR IN )& SAMPLING APPLICATIONS WHERE THE )& NOISE BANDWIDTH IS OFTEN LESS THAN  OF THE .YQUIST BANDWIDTH )N THIS CASE  THE TOTAL INPUT AND !$ CONVERTER NOISE MUST BE SUFFICIENT TO WHITEN THE QUANTIZATION NOISE  AND THE POWER SPECTRAL DENSITY OF THE INPUT NOISE SHOULD BE SUFFICIENTLY GREATER THAN THAT OF THE !$ CONVERTER  AS ILLUSTRATED IN &IGURE  )N SOME CASES  OUT 
 0!,3!2 SENSOR v IN  0ROCEEDINGS )%%% 'EOSCIENCE  AND 2EMOTE 3ENSING 3YMPOSIUM )'!233  !LASKA  )%%%    - 3HIMADA  - 7ATANABE  4 -ORIYAMA  AND 4 4ADONO  h0!,3!2 CHARACTERIZATION AND INITIAL  CALIBRATION v IN  0R OCEEDINGS )%%% )NTERNATIONAL 'EOSCIENCE AND 2EMOTE 3ENSING 3YMPOSIUM  )'!233  $ENVER  #/  )%%%    ! -OREIRA  ' +RIEGER  $ (OUNAM  - 7ERNER  3 2IEGGER  AND % 3ETTELMEYER   h4AN$%- 
 BEAM CLUTTER 2ANGE ACCURACIES ON THE ORDER OF  OR  MILES CAN BE REASONABLY ACHIEVED {°xÊ  " 
 The interesting property of the matched filter is that no matter what the shape of the  input-signal waveform, the maximum ratio of the peak signal power to the mean noise power  is simply twice the energy E contained in the signal divided by the noise power per hertz of  band width No. The noise power per hertz of bandwidth, No, is equal to kTo F where k is the  Roltzmann constant, To is the standard temperature (290 K), and F is the noise figure.  The matched filter and the correlation function. 
 16.29  17. Pulse Doppler Radar   ............................................... 17.1  17.1 Characteristics and Ap plications  ............................ 
 The number of taps equals the  number of pulses to be integrated. The outputs from each of the taps are tied together to form  the sum of the previous n pulses. One of the advantages of this integrator is that any type of  weighting may be applied to the individual pulses by simply inserting the proper altenuation  at each tap of the delay line. 
 19. R. M. 
 ,/1, 
 Alimitedtuningrange,oftheorderof1percent, canbeobtained byascrewinserted in thesideofoneoftheresonator holes.Thistypeofadjustment isusefulwhenthenormalscatter offrequencies expected ofuntuned magnetrons requires thefrequency tobefixedtoaspecified value. Infrequency-agile radarsystems, themagnetron frequency mightbechanged pulse-to­ pulseinsuchamannerthattheentiretuningrangeiscovered. Suchradarsmightbeemployed forECCM,improving thedetection oftargetswithfluctuating crosssectionandreducing the effectsofglint(Sec.5.5).Withahightuningrate,thepulse-to-pulse frequency canbemadeto appearpseudorandom, especially ifthepulserepetition frequency orthetuningrateisvaried rapidly. 
 NALS #ONTINUING ADVANCES IN SAMPLING SPEEDS ARE LEADING TO SAMPLING AT INCREASING FREQUENCIES  SOMETIMES ELIMINATING THE NEED FOR A SECOND DOWNCONVERSION  WITH THE POSSIBILITY APPROACHING OF SAMPLING DIRECTLY AT THE RADAR 2& FREQUENCY 4HE BENEFITS OF )& SAMPLING OVER CONVENTIONAL ANALOG )1 DEMODULATION ARE L 6IRTUAL ELIMINATION OF ) AND 1 IMBALANCE L 6IRTUAL ELIMINATION OF $# OFFSET ERRORS L 2EDUCED CHANNEL 
 WAVE IMPLEMENTATION AND INNOVATIVE SIGNAL PROCESSING /VERVIEW 4HE SURFACE 
 The factors are interdependent, and mutual compatibility is essential. A set of definitions that are believed to be mutually compatible will be given here. Also, information needed for evaluating these factors will be given in- sofar as is practicable. 
 PHASE  )  AND QUADRATURE  1  SIGNAL SAMPLES SAMPLED  AT THE RADAR 024  AT A GIVEN RANGE AND  SK  IS ITS COMPLEX CONJUGATE )T IS CLEAR THAT THIS  ALGORITHM REQUIRES  . COMPLEX MULTIPLICATIONS FOR A TIME SERIES OF  . SAMPLES WHEREAS  THE &&4 REQUIRES  . LOG . 4HIS SO 
 Owing to this high degree of range  foldover, all range gates will have approximately equal clutter. FIGURE 4.9  Plan view of range-gate and doppler-filter areas. Radar altitude = 10,000 ft; velocity =  1000 kt to right; dive angle = 10°; radar wavelength = 3 cm; PRF = 15 kHz; range gate width = 6.67 µs;  range gate = 4; doppler filter at 2 kHz; bandwidth = 1 kHz; beamwidth = 5° (circular); main-beam azimuth =   20°; depression angle = 5°. 
 The sidelobes arc all of equal magnitude. Dolph80 derived the aperture  illumination with this property by forcing a correspondence between the Chebyshev poly­ nomial and the polynomial describing the pattern of an array antenna. Although a radiation  pattern with the narrowest beam width for a given sidelobe level seems a reasonable choice for  radar. 
 TO 
 UNITS "ECAUSE THE BAROMETRIC PRESSURE AND WATER VAPOR CONTENT OF THE ATMOSPHERE DECREASE  RAPIDLY WITH HEIGHT WHILE THE TEMPERATURE DECREASES SLOWLY WITH HEIGHT  THE INDEX OF  REFRACTION  AND THEREFORE REFRACTIVITY  NORMALLY DECREASES WITH INCREASING ALTITUDE 7HILE A RADAR ENGINEER MAY LIKE TO CONSIDER REFRACTION IN TERMS OF  . 
 It is informative to compare measurements by different investigators in differ- ent parts of the world under similar wind conditions. Figure 13.5 displays mea- surements of vertically polarized sea clutter down to a grazing angle of 20° for wind speeds of about 15 kn.from three independent experiments using airborne radars at C-, X-, and K-band frequencies.27'29 While there is no assurance that all these measurements were made over fully developed seas, it is clear that there is a rather strong consistency among them, which reinforces the observation made in reference to Fig. 13.4 that the frequency dependence of sea clutter at interme- diate grazing angles is weak at microwave frequencies from L to K band. 
 The Cassegrain antenna (Fig. 6.21), derived from telescope designs, is the most common antenna using multiple reflectors. The feed illuminates the hyperboloidal subreflector, which in turn illuminates the paraboloidal main re- flector. 
 FREQUENCY CONTOURS ARE GIVEN IN -(Z  EXTENDING FROM THE RADAR  TO A POINT EAST  NMI DOWNRANGE  FOR A *ANUARY NIGHT EXAMPLE &)'52%   0LASMA 
 93–100, January 1998. 121. D. 
 ENERGY DISTRIBUTIONS AND PROB 
 Other reported measurements at low grazing angles of heavily wooded,  rolling hills typical of New England show o0 at these angles to be unaffected by changes in  season or weather.39  There also exists much experimental data of the a0 of crops such as corn, soybeans, milo,  alfalfa, and The radar backscatter depends not only on the type of crop, and  frequency, but also on the state of its growth, the moisture content of the soil, and the time of  day.  There is wide variability in the clutter measurements made by different experimenters  under supposedly similar conditions. Some of these differences are due to lack of adequate  ground-truth data, accurate system calibration, or accurate data proce~sing.~~ There is usirally  a practical limit as to how well the significant ground-truth can be measured and how accilrate  a system can be calibrated. 
 PUT &IGURE    THAT ARE COMBINED TO PRODUCE THE GREATER THAN  K7 PEAK POWER LEVEL 4WO MODULES AND A  6 DC POWER SUPPLY MAKE UP A SINGLE TRANSMITTING GROUP 4HE MODULE CONSISTS OF A  
 PASS FILTERING  THIS GIVES THE DC ERROR VOLTAGE OUTPUT TO THE SERVO AMPLIFIER TO CORRECT THE ANTENNA POSITION &)'52%   "LOCK DIAGRAM OF A CONVENTIONAL MONOPULSE TRACKING RADAR. 
 POLARIZED GAIN ANYWHERE IN THE ANTENNA PATTERN SHOULD BE GREATER THAN  D" TO PROVIDE PROTECTION AGAINST COMMON CROSS 
 A uniformly illuminated monopulse array12 has the difference signal ∆ in quadra - ture with the sum and has the amplitude relationship  ∆( ) ( )tan s in θ θπ λθ = ∑  W  (3.9) where W is the distance between the phase centers of the two halves of the antenna.  Hence, a choice of W = 2VxTp and k = 1 would ideally result in perfect cancellation. In practice, a sum pattern is chosen based on the desired beamwidth, gain, and  sidelobes for the detection system requirements. 
 N. Levanon and E. Mozeson, Radar Signals , New York: John Wiley & Sons, Inc., 2004. 
 RATE $30 BEFORE DISCRETE 
 The line of sight to the  Figure 5.12 Wavefront phase relationships in phase-  comparison monopulse radar.  TRACKING RADAR165 squinted beamsisnotaneasytask.Nutation, whichpreserves theplaneofpolarization, iseven moredifficult. Rotation oftheheamscauses theplaneofpolarization torotatewhichcan causeundesirahle targetamplitude lluctuatiolls atthescanrate.Although suchrtuctuations aretheoretically removed bythemOl1opulse typeofprocessing, inpractice theremoval isnot complete andangular errorcanresult.R6Withmodern solid-state technology, theneedfora thirdreceiver intheconventional mOl1opulse tra,ckermightnotbeasdifficult-to realizein practice astilecomplexity ofproperly scallning apairofsquinted beams.Generally itcanhe saidthaItheamplitude-comparison 111OIlopulse tracking systemisusuallypreferred overthis hyhridtechnique, Phase-comparison monopulse. 
 D" BEAMWIDTH IS LARGER THAN THAT OF A UNIFORMLY ILLUMINATED ARRAY WITH A LINEAR PHASE FRONT "ROADENING THE BEAM ON TRANSMIT REDUCES THE GAIN OF THE TRANSMIT BEAM  BUT THIS LOSS IN GAIN MAY BE NECESSARY TO PRODUCE THE SEARCH FRAME TIME REQUIRED /N RECEIVE  MULTIPLE BEAMS ARE SIMULTANEOUSLY FORMED IN A CLUSTER THAT COVERS THE VOLUME ILLUMINATED BY THE TRANSMIT BEAM %ACH RECEIVE BEAM HAS THE FULL GAIN AND BEAMWIDTH OF A SINGLE BEAM ARRAY WITH THE SAME APERTURE DIMENSIONS )N THE CLUSTER OF RECEIVE BEAMS  EACH OF THE RECEIVE BEAMS MAY BE OFFSET IN VARIOUS DIRECTIONS FROM THE CENTER OF THE SPOILED TRANSMIT BEAM !N EXAMPLE OF FOUR SIMULTANEOUS RECEIVE BEAMS IN A CLUSTER IS SHOWN IN &IGURE  4O SEARCH THE SAME VOLUME COVERED BY THIS FOUR BEAM CLUSTER WITH A SINGLE BEAM RADAR WOULD TAKE APPROXIMATELY FOUR TIMES AS LONG SINCE THE TRANS 
 This is rarely the case for radar systems. However, many ASICs have been devel - oped to support the communication industry, such as digital up- and downconverters,  which can be utilized in radar systems. The introduction of the Field Programmable Gate Array (FPGA) in the 1980s  heralded a revolution in the way real-time DSP systems were designed. 
 STATE TRANSMITTER  4HIS APPROACH  ALLOWS FOR VERY FLEXIBLE ELECTRONIC SCANNING OF THE BEAM ./!!  OPERATES A NET 
 20,.pp. 1-28, January, 1948.  34. 
 MUM VALUE IN MANY APPLICATIONS  IT SHOULD BE LARGER 4HE AMPLITUDE MEASUREMENT IS USED ALONG WITH 4O!  FOR DERIVING THE SCAN PATTERN OF THE EMITTER  4HE CLASSIFICATION OF RADAR INTERCEPTION SYSTEMS IS BASED ON THE TYPE OF REPRESEN 
 Blake, Electronics Consultant (CHAPTER 2) Michael T. Borkowski, Raytheon Company (CHAPTER 5) Leopold J. Cantafio, Space and Technology Group TRW (CHAPTER 22) Theodore C. 
 KNOWN 2AYLEIGH CRITERION  WHICH STATES THAT TWO EQUAL 
 2012 ,9, 75–79. [ CrossRef ] 20. Wakabayashi, H.; Matsuoka, T.; Nakamura, K.; Nishio, F. 
 Milne, K.: The Combination of Pulse Compression with Frequency Scanning for Three-dimensional  Radars. The Radio and Electronic E,rgr., vol. 28. 
     WHERE 0D SS;K= IS THE SINGLE 
 Taking these factors into account, the clutter returns atPoint 1,Fig. 5.15, may bevery crudely. SEC, 5.11] PULSE-MODULATED DOPPLER SYSTE.\f 155 estimated as100dbabove thenoise ina103-cycle band, or130dbabove that inal-cycle band. 
 For best performance the velocity of the surface wave should be very close to that of free space. If the array contains waveguides or horns loaded with dielectric, the velocity will decrease slightly. Further, if the dielectric protrudes from the radiators or if a dielectric sheet is used in front of the array, the velocity of the surface wave may decrease dramatically. 
 The antenna isaparaboloid 18in.indiameter, fedatthe3-cm band bya. 290 ANTENNAS, SCANNERS, AND STABILIZATION [SEC. 9.12 pressurized allthe way from the transmitter-receiver unit through a flexible section tothe scanner, the azimuth rotary joint, and the tilt joint tothe feed, which isenclosed inahollow Styralloy ball. 
 The method of locating the target position is similar in either radar. Both require the  measurement of a distance arid the angle of arrival in two orthogonal angular coordinates. The  distance measured by the bistatic radar is the sum S = D, + D,, the total scattered path. 
 WAVE TUBES 4HE CHARACTERISTIC  SIZE OF THE INCREMENTS OF THE 2& STRUCTURE OF SLOW 
 Eng. 2018 ,43, 258–266. [ CrossRef ] 18. 
 Ifthe frequency issufficiently low,thecrosssectionofsmallaircraftormissiles mightbesmaller thantheirmicrowave values. Itwasmentioned thatexternal sourcesofinterference fromotherHFuserscanlimitthe sensitivity oftheHFradarreceiver. Thusthedesignoftheradarformaximum performance willdifferfromthatwhenreceiver thermal noisesetsthelimit.Inaddition tosatisfying the needsforanadequate signal-to-noise ratio,theremustbeadequate signal-to-c1utter ratio.. 
 BULENCE EFFECTS ON TARGET MOTION AND TARGET ASPECT !N EXAMPLE OF A MEASURED ANGLE  SCINTILLATION SPECTRUM IS SHOWN IN &IGURE  4YPICAL VALUES OF  " AT 8 BAND  IN RELA 
 forazimuth and elevation, ashave spiral scanners. 9.11. Data Transmission .-The continuous transmission ofinforma- tion from thescanner totheindicator, giving theattitude oftheantenna inrelation toitsbase, isknown as‘fdata transmission. 
 25. Dyck, J. D., and H. 
 A challenge problem for 2D/3D imaging of targets from a volumetric data set in an urban environment. Proc. SPIE 2007 ,6568 . 
 13.4). The persistent phosphors, which emit apredominantly yellow ororange light, are composed ofcopper-activated zinc-cadmium sulphides, the zinc-. SEC. 
 and 10 cm. radars showing the effects of sea clutter. On the 10 cm. 
 Logical designofanentireradarsystembycom­ puteristherefore difficult anddangerous. Experience andeducated guessesarestillnecessary inmanycases,justasistrueofotherengineering disciplines inwhichreasonable design decisions mustbemadeonthebasisofincomplete information orconflicting constraints. Itis forthesereasonsthatdifferent designgroups, inmeeting thesameuser'srequirements, often produce different radardesigns thatbearlittleoutward resemblance tooneanother, yet accomplish thesameobjectives.. 
 (a) Comparison with the cosecant-squared pattern; (b) free-space coverage  diagram. {From Sl,rader,91 co11rtesy McGraw-Hill Book Company.) . 262 INTRODUCTION TO RADAR SYSTEMS  7.8 EFFECT OF ERRORS ON RADIATION PATTERNS73·99 101  Antenna-pattern synthesis techniques such as those discussed in Sec. 
  AND  %23 
 For the filter design, a clutter attenuation 10 dB below  these requirements will be needed to keep the sensitivity loss due to the clutter residue  below 1 dB and also because each doppler filter will have a coherent gain of around  10 25 1410⋅ =log ( ) d B, this must be added to the filter design specification as well. The  total S-band doppler space for the above radar parameters is 300 m/s, and assuming that  the land clutter suppression region has to be ± 4 m/s and that the moving clutter suppres - sion region has to be ± 30 m/s, the constraint for all doppler filter designs normalized to  their peak is as shown in Figure 2.58. Using a signal processing toolbox developed by Dr. 
 This allows cancellation to be made every interpulse period, maintaining the effective PRF equal to the basic PRF. The two-way patterns from the antenna at A1 and A2 must be nearly identical; otherwise, cancellation will be degraded. This degradation may be calculated by measuring the two antenna patterns, G1(Q) and G2(O), and then calculating the correlation coefficient [/G12WGf(OWe]2 P = -7 ^ (16.6) J [G1(O)]Ve J [G2(O)]Ve The resultant cancellation ratio is then CR = 10 log [1/(1 - p)] (16.7) IfG2(O) is nearly identical to G1(O), then p is approximately equal to 1 and the cancellation ratio is large. 
 However, echoesmay be reﬂected to the antenna if the conical surface is rough. Texture The texture of the target may modify the effects of shape and aspect. A smoothtexturetendstoincreasethereﬂectionqualities,andwillincreasethestrength of the reﬂection, but unless the aspect and shape of the target aresuch that the reﬂection is focused directly back to the antenna, the smoothsurface will give a poor radar echo because most of the energy is reﬂected inanother direction. 
 In addition, a ship’s heading is normally available within a data box outside of the  operational area. The radar origin can be offset from the center of the operational area  by the user; the bearing scale adjusts accordingly. Two or more electronic bearing lines  (EBLs) have to be provided with continuous  numerical readout. 
 The probability margin R ensures the selection of the proper DF radar association  (avoiding rapidly changing decisions) when there are two or more radar tracks close  to one another. The correct selection is reached by postponing a decision until the two  highest association probabilities differ by R. The value for R is found by specifying a  probability of an association error Pe according to Pe = P (Pmax ≥ Pnext + R), where  Pmax corresponds to an incorrect association and Pnext corresponds to the correct  association. 
 Zambresky: The Fleet Numerical Oceanogra- phy Center Global Spectral Ocean Wave Model, Bull. Am. Meteorol. 
 Disagreements  often result from the oversimplifying nature of the assumptions or in the model used in  formulating the calculations. A good radar design is one which is not overly sensitive to small  variations in the model or the assumptions.  Atmospheric and urban noise. 
 BASED REMOTE SENSING RADARS IS SUBJECT TO RAPID CHANGE 4HIS CHAPTER PROVIDES THE VIEW FROM  THE EARLY ST CENTURY 2EADERS ARE ENCOURAGED TO SEEK CURRENTLY TOPICAL INFORMATION THROUGH ONLINE RESOURCES  +EYWORDS  SUCH AS THE NAMES OF THE MISSION  NATIONALITY  AND RADAR  ARE USUALLY SUFFICIENT TO LOCATE SEVERAL REFER 
 The coherent procedures r e- quire a good short -time stability of the tr ansmission signals (see pulse Radar, chapter 8).   4.3 Direction (Azimuth, Elevation)   Antennas generate a plane wave in the far field.  They also mainly receive the plane wave from the  far field, which corresponds to the alignment of the antenna. 
 Thus when the system instabilities are high, the detection of targets in clutter can be seriously  degraded. One approach for operating under such conditions is to use two limiters. 39 One  limiter is placed before the pulse-compression filter and has an output dynamic range equal to  the difference between the peak transmitter power and transmitter noise in the system band­ width. 
   4AYLOR N     
  
 PULSE BINOMIAL CANCELER   PULSE 
 When more directivity is required than can be obtained with a simple open-ended  waveguide, some form of waveguide horn may be used. The waveguide horn is probably the  most popular method of feeding a paraboloid for radar application.  Optimum feed illumination angle. 
 It should not have any flat, cylindrical, or conical surfaces which  might be illuminated by the incident radar wave from a direction along the normal to the  surface. The cone-sphere, described in Sec. (2.7), is a good example of a target shape that yields  a low val,ue of cross section over a wide range of angles. 
 Microwave Monolithic Integrated Circuits (MMICs).  During the 1990s, it  was the reduction-to-practice of the microwave monolithic integrated circuit (MMIC)  that enabled most high frequency phased arrays to be realized. MMIC use in T/R  module design has enabled bold new module configurations, and hence phased array  systems, to be envisioned. 
 The auxiliary  antennas provide replicas of the jamming signals in the radar antenna sidelobes.  To this end, the auxiliary patterns approximate the average sidelobe level of the  radar receiving pattern. In addition, the auxiliaries are placed sufficiently close to  the phase center of the radar antenna to ensure that the samples of the interference  that they obtain are statistically correlated with the radar jamming signal. 
 FED SERIES FEED  IT IS NECESSARY TO CONSIDER BOTH THE FEED  EFFECT AND THE APERTURE EFFECT 4HE TOTAL FREQUENCY SCAN OF THIS FEED WILL BE   $$$PPP  oF FF FGTANCOSL LRAD #7   #ENTER 
 237-245, April, 1962.  39. Caspers, 3. 
 Radar–87 ,  Conf. Pub. 281, London, October 19–21, 1987, pp. 
 The 55-W transistors provide a minimum of nearly 7.0-dB gain from 1215 through 1400 MHz from a 28-V dc power supply. All three devices are beryllia- based transistors that are soldered into a metal-ceramic hermetic enclosure, a photograph of which is shown in Fig. 5.12. 
 SBR System Costs. The author uses a cost-estimating ratio for SBR satellites of $64,000 per kilogram in 1988 dollars that is based upon informal study of many satellites that have been placed into orbit. Launch costs are not included; they depend upon the launch vehicle. 
 Yueh, “Microwave remote sensing modeling of ocean surface salinity and winds using  an empirical sea surface spectrum,” in Proceedings IEEE Geoscience and Remote Sensing  Symposium , Anchorage, AK, 2004. 142. S. 
 ENTIATE BETWEEN DEFINITIONS WHEN USING THIS TERM   . EFF   ;3).!$D"   
 It is only compatible with phase-discrimination constant false-alarm rate (CFAR; Sec. 3.13), but it serves a useful purpose in radars utilizing this CFAR process after doppler filtering. Characteristics. 
 SCAN DATA CORRECTED FOR SPREADING LOSS AND ATTENUATION #OURTESY )%%  . 
 DOPPLER CELL &IGURE  SHOWS THE SIGNAL PROCESSING THAT MIGHT BE FOUND IN $"3 MODE )T  CONSISTS OF MULTIPLE TIME AROUND ECHO -4!%  SUPPRESSION  AMPLITUDE WEIGHTING TO IMPROVE SIDELOBES  PRESUMMATION  AN &&4 FILTER BANK  MAGNITUDE DETECTION IN EACH USABLE FILTER OUTPUT  PLACEMENT OF EACH FILTER OUTPUT IN THE CORRECT GROUND STABILIZED LOCATION FOLLOWED BY POST DETECTION INTEGRATION  AND SCALING FOR THE DISPLAY FOR CON 
 332-337, American Meteorological Society, Boston, 1981. 47. Mueller, E. 
 MONOSTATIC REGION &OR EXAMPLE  A n BISTATIC ANGLE CORRESPONDS TO A   SHIFT IN WAVELENGTH AND USUALLY CAN BE IGNORED "OTH VERSIONS OF THE EQUIVALENCE THEOREM ARE VALID WHEN THE POSITIONS OF THE TRANSMITTER AND RECEIVER ARE INTERCHANGED  GIVEN THAT THE TARGET 
 This requires a large frequency range of operation, high power to overcome  propagation losses, and diagnostics of the ionospheric conditions to determine proper radar  parameters.  Example capabilities. The following describe the nominal performance capabilities that might  be achieved with an over-the-horizon radar operating in the HF band :20  Range coverage-1000-4000 km; longer ranges are possible with multihop propagation, but  with degraded performance. 
 SHAPED HIGHLY EFFICIENT GRID OF WIRES REFLECTIVE TO PARALLEL POLARIZA 
 14. Greene, J. C., and J. 
 91. Hutchison, P. T.: The Image Method of Beam Shaping, I RE Trans., vol. 
 304 9.17 Stabilization ofthe Beam. 305 9.18 Data Stabilization. 311 9.19 Installation ofAirborne Scanners 312 9.20 Installation ofSurface-based Scanners 313 9.21 Radomes ......... 
 REFERENCES  I. Southworth, G. C.: "Forty Years of Radio Research," Gordon and Breach. 
 , 
 AGE OF   HOURS FOR ALL NINE CLASSES OF TUBES (E ALSO SAYS THAT 474S FOR SPACE APPLICATION  WHICH ARE OF LOWER POWER THAN RADAR 474S  HAVE -4"&S OF THE ORDER OF ONE MILLION HOURS  $EPRESSED #OLLECTOR  4HE EFFICIENCY OF A 474 OR A KLYSTRON CAN BE IMPROVED  BY THE USE OF A SO 
 Applying this  algorithm to Table 7.6 results in detection no. 8 updating track no. 1, detection no. 
 7.3 FIG.7.9.—Photograph transmitted byvideo mapping techniques.. SEC. 7.4] THE RELAY OF RADAR DISPLAYS 225 orofany deliberate oraccidental deformation ordistortion. 
 The noise level calibration algorithm must be designed to  tolerate external interference and returns from rainstorms or mountains at extreme range. Another concern with amplification prior to STC is that the noise level at the output  of the STC attenuator varies with range. At close range, the noise level into the A/D  converter may fall below the quantization interval. 
 20, 1975.  72. Hsiao, J. 
 -ADJAR  h# 
 Under conditions ofhigh atmospheric humidity, N FIG.3.37.—Detroit, Mich. TheFord Rouge River plant shows asabright patrh 7mi southeast oftheamcraft. Wavelength =1.25cm,0,8°beam, altltude 4000 ft.radius 10 IMUtiCal mi. 
 on  Advanced A/D and D/A Conversion Techniques , July 1999. 119. G. 
 FREQUENCY WAVEFORM BECAUSE  IT PROVIDES A MUCH SIMPLER EXAMPLE FOR EXPLAINING THE PRINCIPLE OF RANGE RESOLUTION .   39.4(%4)# !0%2452% 2!$!2   £Ç°Ç ,ET US ASSUME THAT THE RADAR TRANSMITS A STEP 
 E. Green, Jr., “Radar measurements of target scattering properties,” In Radar Astronomy ,   J. V . 
 8.16. This type of feed is known as a snake feed, serpentine, or sinuous feed. Other  slow-wave transmission lines can be used for the feed, including helical wa~eguide~~.'~ and  corrugated waveguide." The configuration of Fig. 
 BAND TUBES IS REPLACED BY A WIDEBAND CLUSTERED 
 Both gain and  noise figures are highly depen - dent on the pinch-off voltage  when the FET is biased close to  pinch-off. Because the pinch-off  voltage can vary among devices  from the same wafer, the bias  condition must be chosen care - fully. Gain and noise figures are  usually traded off against repeat - able performance. 
 A more generic pair of principal planes for antennas in general are the so-called E and H plane of a linearly polarized antenna. Here the E-plane pattern is a principal plane containing the direction of the electric (E-field) vector of the radiation from the antenna, and the H plane is orthogonal to it, therefore containing the magnetic (//-field) vector direction. These two principal planes can be independent of earth-oriented directions such as azimuth and elevation and are widely used. 
 Under these conditions, the location of the  target position is indeterminate other than that it lies somewhere along the line joining the  transmitter and receiver. .)  Locating a target with bistatic radar is not unlike locating a target with monostatic radar.  The latter measures the total path length from radar to target to receiver jusl as doi.:s thi.:  bistatic radar. 
 The combi111,tion of a linear array and parabolic cylinder can also generate a pencil beam.  The endfire array is a special case of the linear or the planar array when the beam is  directed along the array. Endfire linear arrays have not been widely used in radar applications. 
 64. J. R. 
   
 TrackIIICl;llte'IllIlCl'. ortrackupdate.byacquiring newdataandconsolidating itwithexisting tracks. Userserrices, whereby thespecificinformation desiredbytheuserisacquired, suchasobtain­ ingasatellite ephemeris orthesolution ofafire-control problem.. 
                                                 
 DIMENSIONAL MEASUREMENTS OF TERRAIN SHAPE  WITH A RESOLUTION OF n KM 0IONEER 6ENUS WAS HOST TO  EXPERIMENTS WITH A TOTAL MASS OF  KG   INCLUDING A  RADAR ALTIMETER /2!$   WHICH ALSO PRODUCED RUDIMENTARY SURFACE MAPS AS THE RADAR BEAM WAS SCANNED IN THE PLANE ORTHOGONAL TO THE ORBIT BY THE SPACECRAFTS  20- SPIN 
 At approximately ±5% from the design doppler, the perfor - mance starts to fall significantly below the optimum.FIGURE 2.24  Approximate MTI improvement factor limitation due to pulse-to-pulse staggering  and internal-clutter motion (all canceler configurations): I(dB) = 20 log [0.33/( l − 1) (g   fr /sv)];   g  = maximum period/minimum period ch02.indd   29 12/20/07   1:44:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 For simplicity, assume the Benedict-Bordner constant relationship41 [b  = a2/(2 - a)]  between a  and b. 
 MODULATION COMPONENTS BY  D"  THE CRITICAL FREQUENCIES BEING THOSE WHICH CHANGE PHASE BY ODD MULTIPLES OF  DURING THE TIME PERIOD BETWEEN TRANSMISSION AND RECEPTION OF THE CLUTTER RETURN FROM A SPECIFIED RANGE. È°£È  2!$!2 (!.$"//+  4HIS RANGE 
 SANDWICH IS NOT COMMONLY USED BECAUSE THE CORE DIELECTRIC CONSTANT IS QUITE HIGH FOR A PROPER MATCH # 
 They are com- plicated, bulky, and expensive, and thefunction they perform can rather simply bedone byother means. Dead-reckoning Computers.—The direct comparison ofthe PPI with anappropriate chart isanunnecessary elegance ifitisdesired merely to take occasional fixes and toproceed between fixes bytheusual methods ofdead reckoning. This is,inany event, theonly safe means ofnaviga- tion. 
 MERS CAN DESIGN THE SYSTEM WITHOUT KNOWING THE INTIMATE DETAILS OF THE HARDWARE !LSO  THE SOFTWARE DEVELOPED TO IMPLEMENT THE SYSTEM CAN TYPICALLY BE MOVED RELA 
 There are also  "point" clutter echoes, such as towers, poles, and similar objects. The echo from a single  bird is also an example of point clutter. When clutter echoes are sufficiently intense and  extensive, they can limit the sensitivity of a radar receiver, and thus determine the range  performance. 
 As seen in Fig. 5.16, the angle errors due to multipath at low  angle are cyclical. This is a result of the direct and surface-reflected signals reinforcing and  174INTRODUCTION TORADAR SYSTEMS image.Thetracking hasbeendescribed as"wild"andcanbegreatenoughtocausetheradar tobreaktrack.Theeffectismostpronounced overasmoothwatersurfacewherethereflected signalisstrong.Theeffectcanbesogreatthatitcanbecomeimpossible totrackta'rgetsatlow elevation angleswithaconventional tracking radar.Inaddition tocausing errorsinthe elevation-angle tracking, itisalsopossible forsurface-reflected multipath 'tointroduce errors intheazimuth-angle tracking; eitherby"cross-talk" intheradarbetween theazimuth and elevation errorchannels, orbythetarget-image planedeparting fromtheverticalaswhenover slopinglandorwhentheradarisonarollingandpitching ship. 
 45, no. 2, pp. 261–266, 1995. 
 F.: A Solution to the Problem of Rapid Scanning for Radar Antennas, J. Appl. Pli_vs .. 
 Hanuise, “An HF phased array radar for  studying small-scale structure in the high latitude ionosphere,” Radio Science , vol. 20, pp. 63–79,  January–February 1985. 
 WAVE APPLICATIONS !CCORDING TO  THE #OMMUNICATIONS  0OWER )NDUSTRIES #0)  BROCHURE  ITS 6+"  MILLIMETER 
 V IF V   O  OR  
 .AVIGATION CONCEPT  E FOR ELECTRONICENHANCED  4HE CONTINUED NEED FOR RACONS OR  A REPLACEMENT TECHNOLOGY WILL INEVITABLY FORM PART OF THIS PROGRAM )F THE CONTINUOUS AVAILABILITY OF PRECISE POSITIONAL INFORMATION CANNOT BE TOTALLY RELIED UPON  THEN IT IS PROBABLY ESSENTIAL THAT SOME FORM OF SHIP 
 Atlas, R. C. Beal, R. 
 (In practice.  the resoluticfn is said to be about 500 m.46) If limitations on peak power require a co.nsidcrably  longer pulse width in order to achieve the necessary energy within the pulse. some form of  pulse compression could be used. 
 AGED ERROR SIGNAL CONTROLS A VOLTAGE 
 INCH CENTERS -OUNTED DIRECTLY BEHIND EACH ROW FEED IS A DEDICATED ROW TRANSMIT 
 K. M., F. V. 
 CAUSED ERRORS 4HE DATA ILLUSTRATES WHICH ERROR SOURCES DOMINATE AT DIFFERENT REGIONS OF THE RADAR RANGE AND THEIR CHARACTERISTICS VERSUS RANGE 4HE TARGET 
 tClustered-cavity klystron can achieve 10 to 15 percent bandwidth at higher cost. JIn 1-MHz bandwidth. Weight. 
 itisusuallydesiredtohavetherangeresolution equaltothealong-track, orcross-range resolution. Whenopticalproces"ing isemployed, the linearFM.orchirp.pulse-compression waveform readilylendsitselftothesametypeof processing asdescribed forthecross-range signa!.7Theformofthelinea'FMsignalinthe rangedimension issimilartotheformofthesignalinthecross-range dim~nsion. Thelinear FMsignalhasaphasethatvariesast2(t=time),andthecross-range signaihasaphasethat variesasx2(x=distance alongthegroundtrack).Justasthephasehistory)fthe cross-range signalrecordsonfilmasaFresnel zone-plate, whichthenhasafocusing actionwhenjHu­ minated hycoherent light,sodoesthesignalofthelinearFMwaveform alsorecordasa Fresnelzone-plate. 
 McGraw-Hill Book Company, New York, 1970.  6. IEEF Test Procedures for Antennas. 
 it  is \CCII ill rlie I;IIIIC II~;II tlic 4-f;~ce ;IrI;ly requires the fewest eler~ie~its. However, if tlie healii-  widtli~ at tile ~naxiriiurrl scan are to be the sanie, the 6-filce array requires the fewest total  riilriiher of eletnents. When tlie criterion is to maintain either the average gain or the average  he;~~~lwidtti tlie s;~nic otrer (lie scan, the 4-face array yields the minimum total number- of  elements. 
 lt is probably the  preferred tube for most high-power radar applications if its high operating voltage and large  size can be tolerated. The traveling-wave tube is similar to the klystron. It differs from  the klystron in having wider bandwidth, but at the expense or less gain. 
 The greatest efficiency is obtained  with a reflector in which the radiation from the feed in the direction of the edges is between 8  and 12 dB below that at the center. As a rough rule of thumb, the intensity of the energy  ;;.!? 80 - OJ  L  :::, ...  !;; 60 - a. 
 If no targets are correlated, it sug - gests that own ship has a significant problem, perhaps with its radar, GNSS position,  or more commonly, a gyrocompass offset. If there is good positional tie-up or even an understanding of why radar informa - tion may be lacking, for example, due to heavy sea clutter, the additional information  transmitted on AIS can be extremely useful. For instance, a target’s heading is trans - mitted by AIS. 
 contrast, the bias errors introduced by the multipath in the low-angle squinted- sum-beam technique are kept to peaks on the order of 0.15 in u space, corre- sponding to an rmse of approximately 4.7 msines for a radar of the same aperture. Further reduction might be possible with an optimization of the beam placement and aperture illumination functions. REFERENCES 1. 
 6 (Supplemerit), pp. 226-235, November, 1967.  85. 
 This  requirement naturally leads to extreme stability master oscillators and ultra low-noise  synthesizers.44 Air-to-Air Mission Profile.  Just as with an air-to-surface mission, the mode  structure of a modern fighter aircraft air-to-air mission arises from its profile.45 A typi - cal mission profile for air-to-air (A-A) is shown in Figure 5.12. The mission profile  ch05.indd   12 12/17/07   1:26:43 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 DUE POWER CAUSED BY THESE CONTRIBUTORS 4HESE PROCEDURES ARE EMPLOYED TO DIAGNOSE THE SOURCE OF RADAR INSTABILITY IN AN EXISTING RADAR OR TO PREDICT THE PERFORMANCE OF A RADAR IN THE DESIGN STAGE AND TO ALLOW THE ALLOCATION OF STABILITY REQUIREMENTS TO CRITICAL COMPONENTS OR SUBSYSTEMS WITHIN THE RADAR -EASUREMENT OF TOTAL RADAR INSTABILITY CAN BE CONDUCTED WITH THE RADAR ANTENNA  SEARCH 
 Bickmore, R. W.: A Note on the Effective Aperture of Electrically Scanned Arrays, I RE Trans.,  vol. A P-6, pp. 
 The RCS curve of the target must be deﬁned to calculate the aspect entropy. Targets of the same type are supposed to have similar aspect entropy, while the aspect entropy of different types of targets are diverse. Thus, targets can be discriminated from each other by using the aspect entropy value. 
 Thus, although we can develop average  models like those described in  Section 16.6, details are much more complex. The s 0 varies with season, moisture  content, state of growth, and time of day. Figure 16.37147 shows the seasonal variation for corn compared with a model  presented in the reference. 
 Ten large birds in a resolution cell will have  an RCS of 0.1 square meter. When multipath reflections occur, such as over the ocean  when the radar beam is centered at the horizon, there can be up to a 12 dB enhancement  of the RCS of the birds, giving an apparent RCS greater than one square meter to the  flock of 10 birds. If there is 1 bird (or bird flock) per square mile, there will be about  3000 bird returns within 30 miles of the radar. 
 Instead, mini joysticks or simple four-way rocker  switches are typically used. The operational area of a radar display is normally circular, although this is no  longer a mandatory requirement. It originates from the historical use of conical display  tubes but is retained by most manufacturers as it gives additional space outside of the  operational area for the display of data and menus (see Figure 22.6). 
 AXIS TRACKING IS LIMITED WHEN TRACKING TARGETS WITH UNANTICIPATED MANEUVERS °ÇÊ -"1, 
  
 Electronics Conf (Chicago). vol. 11, pp. 
 39,   pp. 1715–1726, 2000. ch19.indd   45 12/20/07   5:39:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 ÊÊ  "/" Ê " * 
 For example, with a particular X-band Varian backward-wave CF A, 16 a  constant-voltage modulator produces a variation in output power from 505 kW at 9.0 GHz to  240 kW at 9.5 GHz, a change of 3.2 dB. A constant-current modulator with the same tube  results in a power variation of only 0.3 dB over the same frequency range. Since most practical  modulators are neither constant-current nor constant-voltage devices, actual performance is  somewhere in between. 
 È°În  2!$!2 (!.$"//+  INPUT SIGNAL FREQUENCY AND AMPLITUDE 4HE FREQUENCY OF SPURIOUS SIGNALS IS ALSO DEPEN 
 This collection of wave trains is described by a  two-dimensional spectrum (wave amplitude as a funct~on of water-wavelength and d~rect~on ol'  travel). At grazing incidence the radar responds chiefly to the two wave trains whlch are  traveling toward and aw.iv from the radar, each with a water-wavelength A, equal to half thc  radar-wavelength A,. For ,I grazing angle 4, this cond~tlon becomes A, = (,?,/2) cos 4 The  scattering from these two " resonant" wave components is similar to that from a diffract~on  grating. 
 Wiesbeck, A. Moreira, "Versatile receiver subsystem with digital beamforming on receive only", Proc. 5th International Conference on Radar Systems, Brest, France, Poster Session, May 18- 20, 1999  − Y. 
 The most notori - ous case being in the United Kingdom in 1994, when the gravesites, under concrete  and in the house of Fred West, of the victims of the serial murderer were pinpointed.  In Belgium, the gravesites of the victims of the pedophile, Duteous, were detected  in 1996. FIGURE 21.29  Typical radar image of concrete floor showing rears, joints, mesh, etc: 1 ns pulse - width, horizontal markers every 10 cm, vertical scale 0.5 m ( Courtesy IEE ) Joints Steel Reinf orcing MeshRebar ch21.indd   35 12/17/07   2:51:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 TION OF THE SURFACE OF THE ENTIRE PLANET AT  
 IRE.) . RADAR ANTENNAS 235  Broadband signals. The Fourier-integral-transform relationship between the radiation pattern  E(<J,) and the aperture distribution A(z) as expressed in Eqs. 
 H R YXZ v θ ϕθΔ ()Rt PP Figure 1. Geometry of DBS imaging. 70. 
 T ech. J. 1948 ,27, 623–656. 
 The average vertical temperature gradient of the troposphere varies  between 6° and 7° Celsius per kilometer. The concentrations of gas components of the troposphere vary little with height,  except for water vapor. The water vapor content of the troposphere comes from evap - oration of water from oceans, lakes, rivers, and other water reservoirs. 
 POWER 474 THAT PROVIDES MOST OF THE GAIN OF THE TOTAL AMPLIFIER CHAIN 7HEN  COMPARING THE #&! WITH THE  LINEAR 
 15-20, January, 1975.  49. Cohn. 
 140. T. Fujita, “The downburst,” Satellite and Mesometeorology Research Project, Department of the  Geophysical Sciences, University of Chicago, 1985. 
 ON INCIDENCE .OTE  THAT THE 2#3 IS EXTREMELY SMALL NOT MEASUR 
 102  11.5.3 Arbitrary Flat Disk ................................................................................................ 103  11.5.4 Radar Cross- Section of Further Simple Bodies .................................................... 103  11.6 Calibration Standards for Free Space Measurements ................................................... 
 STATE RADAR WITH PULSE COMPRESSION ^ §S   THE TEMPERA 
 I.: Nonuniform Arrays, chap. 6 in "Antenna Theory, pt. I," R. 
 308-314, May, 1969.  52. Kennaugh, E. 
 The near side of the hill will give a large return, while the far side, which is  relatively hidden from the view of the radar, will give little or no return. The radar cross  section of a farmer's field will differ before and after ploughing. as well as before and after  harvesting. 
 Proc. IEEE 1998 ,86, 2278–2324. [ CrossRef ] 24. 
 Ê*,"*/"  4HE SOLAR ACTIVITY THAT DRIVES THE IONIZATION OF THE %ARTHS UP PER ATMOSPHERE IS VARIABLE  ON A DIURNAL  SEASONAL  AND LONG 
 TOURS ARE CONCENTRIC SPHERES WITH THE RADAR AT THE CENTER  B  #ONSTANT 
 ING FREQUENCY  AND TEMPERATURE AS NEEDED -EASUREMENTS OVER TIME CAN ALSO BE USED TO ASSESS COMPONENT AGING AND POTENTIALLY PREDICT RECEIVER FAILURE PRIOR TO DEGRADATION BEYOND ACCEPTABLE LIMITS !CCURATE GAIN CONTROL IS ESSENTIAL FOR RECEIVER CHANNELS USED TO PERFORM MONOPULSE ANGLE MEASUREMENTS  WHERE AMPLITUDES RECEIVED IN TWO OR MORE BEAMS SIMULTANEOUSLY ARE COMPARED TO ACCURATELY DETERMINE THE TARGETS POSITION IN AZIMUTH OR ELEVATION 2ECEIVER DYNAMIC RANGE IS MAXIMIZED WITH ACCURATE GAIN CONTROL AS TOO LITTLE GAIN CAN RESULT IN NOISE FIGURE DEGRADATION AND TOO MUCH GAIN RESULTS IN LARGE SIGNALS EXCEEDING THE !$ CONVERTER FULL 
 OUT EXCESSIVE COST OR RISK 5NFORTUNATELY  INTERACTION BETWEEN THE POTENTIAL USER OF THE RADAR AND THE RADAR SYSTEMS ENGINEER IS NOT ALWAYS DONE IN COMPETITIVE PROCUREMENTS L )DENTIFICATION AND EXPLORATION OF POSSIBLE SOLUTIONS   4HIS INCLUDES UNDERSTANDING THE ADVANTAGES AND LIMITATIONS OF THE VARIOUS POS 
 (External noiseis discussed inSec.12.8.)Themeasure ofreceiverinternalnoiseisthenoise-figure (introduced previously inSec.2.3). Goodreceiver designisbasedonmaximizing theoutputsignal-to-noise ratio.As described inSec.10.2,tomaximize theoutputsignal-to-noise ratio,thereceiver mustbe designed asamatched filter,oritsequivalent. Thematched filterspecifies thefrequency response function oftheIFpartoftheradarreceiver. 
 FIGURE 6.2  Downconverter spurious-effects chart: H = high input frequency; L = low  input frequency ch06.indd   12 12/17/07   2:03:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 frequency, or phase. An example of an amplitude modulation is the pulse  radar. The narrower the pulse, the more accurate the measurement of range and the broader  the transmitted spectrum. 
 ARRAY CONFIGURATIONS BOTH HAVING  -    SUB 
 BAND SIGNALS DUE TO OUT 
 Root: "Introduction to Random Signals and Noise," McGraw-Hill  Book Co.. New York, 1958.  6. 
 The magnetrons discussed above are referred toas“strapped”. 330 THEMAGNETRON AND1’HEPULSER [SEC. 103 magnetrons. 
 Repeater/deception jamming is a major threat because it might  not be recognizable, whereas the others are, at least in principle, recognizable. The  impact of each threat and the possible countermeasures are described in the remaining  part of this section. • Barrage jammer . 
 Also significant is the fact that the achievable resolution for a given antenna size is independent both of the range and of the wavelength used. A graph of Eq. (21.8) is also shown in Fig. 
 With only one beam at a time, there may not be enough time  available to perform all of the required functions. A digital beamformer allows the  formation of multiple simultaneous beams, allowing the volume surveillance func - tion to be performed much more quickly, allowing more time to do other things. Of  course, in order to form multiple simultaneous receive beams, the transmitted beam  must be made broader to encompass the receive beams, which might require a more  powerful transmitter or more integration on receive to provide the same performance  as a single-beam system. 
 FIFTIETH OF A SCANNED  BEAMWIDTH HAVE BEEN MEASURED WITH SCANS UP TO  n  4HE ACCURACY IS  LIMITED BY PHASE AND AMPLITUDE ERRORS 3INCE PHASE SHIFT RATHER THAN TIME DELAY IS USED  AS THE FREQUENCY IS CHANGED  THE DIRECTION OF THE NULL OF THE SCANNED BEAM IS ALSO CHANGED  AND THE BEAM MOVES TOWARD BROADSIDE WITH AN INCREASE IN FREQUENCY 3HAPED "EAMS  4HE RADIATION PATTERN OF AN ARRAY MAY BE SHAPED BY MODIFYING  THE APERTURE DISTRIBUTION 'OOD PATTERN APPROXIMATIONS CAN BE OBTAINED BY USING PHASE ONLY )N PARTICULAR  THE BEAM MAY BE BROADENED BY APPLYING A SPHERICAL PHASE DISTRIBU 
 2.8] RECEIVERS, IDEAL ANDREAL 31 Weareinterested inthemagnitude of~intheabsence ofsignal, which wedenote by~. Inorder toapply Eq. (16) wemust know theresistance R,cbetween Band C. 
 1 is that a small portion of the CW oscillator power that generates the transmitted  pulses is diverted to the receiv'er to take the place of the local oscillator. However, this CW  signal does more than function as a replacement for the local oscillator. It acts as the coherent  reference needed to detect the doppler frequency shift. 
 SURFACE PREDICTION 3PECULAR REFLECTION IS DEFINED AS REFLECTION FROM A SMOOTH PLANE AND OBEYS THE  &RESNEL REFLECTION LAWS  !T NORMAL INCIDENCE  THE SPECULAR 
   PP n     & ' "ASS AND ) - &UKS   7AVE 3CATTERING FROM 3TATISTICALLY 2OUGH 3URFACES   .EW 9ORK  0ERGAMON 0RESS     # %CKART  h4HE SCATTERING OF SOUND FROM THE SEA SURFACE v  * !COUST 3OC !M   VOL     PP n    0 "ECKMANN AND ! 3PIZZICHINO   4HE 3CATTERING OF %LECTROMAGNETIC 7AVES FROM 2OUGH 3URFACES    .EW 9ORK -ACMILLAN #OMPANY    , " 7ETZEL  h(& SEA SCATTER AND OCEAN WAVE SPECTRA v PRESENTED AT 523) 3PRING -EET  .ATIONAL  !CADEMY OF 3CIENCES  7ASHINGTON  !PRIL   ! + &UNG AND ' 7 0AN  h! SCATTERING MODEL FOR PERFECTLY CONDUCTING RANDOM SURFACES   ) MODEL DEVELOPMENT v )NT * 2EMOTE 3ENSING  VOL   NO   PP n    ' 2 6ALENZUELA  h4HEORIES FOR THE INTERACTION OF ELECTROMAGNETIC AND OCEANIC WAVESA  REVIEW v "OUNDARY 
 4.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 If the main beam were scanned 360° in azimuth with the same radar platform  kinematics, the main-beam clutter would scan in doppler frequency so that it would  appear in the selected filter ten times (twice for each hyperbolic band). In between,  the filter would receive sidelobe clutter from all darkened intersections. With the use  of the proper clutter offset (which would vary as a function of main-beam azimuth)  on the transmit frequency, as described in Section 4.1, the doppler of the main-beam  clutter return will be zero or DC. 
 VERTICAL ANTENNA SEPARATION 6ERTICAL ANTENNA SEPARATION ENABLES ESTIMATION OF THE  HEIGHT OF A TARGET ABOVE THE AVERAGE GROUND HEIGHT OR  MORE GENERALLY  TERRAIN HEIGHT VERSUS LOCATION  #OURTESY  OF 3CI4ECH 0UBLISHING  )NC          
 26–31. 157. R. 
 proximations can be extended to bodies of modest electrical size in the resonance region. Low-frequency approximations developed for the Rayleigh region can ex- tend nearly into the resonance region. Exact Methods Differential Equations. 
 Seliga, and V. Balaji: Remote Sensing of Hail with a Dual Linear Polarization Radar, J. dim. 
 Intheradar operating position astraight piece ofwaveguide with achoke-flange joint ateach end transmits the power direct totheantenna. There is,ofcourse, appreciable r-fleakage atthe airgaps ofthe two junctions. Accurate construction keeps this small enough nottoaffect theAFC mixer inthesame compartment. 
 334 radiation patternof.280-282 randomerrorsin,318-322 reflectarray.309 Reggia-Spencer phaseshifterfor.291-293 series-fed. 285 signalmanagement in,324 snakefeedfor.301 space-fed. 3U8-309 suharrays in.309310 switched-line phaseshifterfor,2R8 thinned, 3U9.319.331-332 triangular elementspacingin,333-334 twin-slah phaseshiftersfor.294 unequally spaced.331-332 ARSR-3,538-541 Artificial dielectric lenses,249-252 ASR,536-537 Asymmetric monopulse. 
 Lynch: Principles and Techniques of Satellite Navigation  Using the Timation II Satellite, Naval Research Laboratory Rep. 7252, June 17, 1971, Washington,  D.C.  67. 
 BAND  ANGLE 
 STATE VALUE  )F THE VOLTAGE AND CURRENT THRESHOLD OF THE TRANSISTOR HAS NOT BEEN REACHED  THE SHORTER PULSE WIDTH OPERATION COULD ALLOW FOR SIGNIFICANTLY LARGER POWER CAPABILITY TO BE DEM 
 Toensure that the weakest signals that areatalldetectable arenot missed, theover-all gain ofthereceiver ishigh enough sothat thermal noise originating inthereceiver (Sec. 2.7) isperceptible onthe display. The two signals that rise significantly above this noise inFig. 
 Scan rates of hundreds of r/min are frequently used—in some instances, as high as 2400 r/min, as in the AN/APN-58 target seeker. In the target seeker application the PRF can be high since the target is at short range. The coming of the jet aircraft caused additional problems for lobing systems be- cause jet turbines cause significant modulations at high frequencies in regions near the maximum practical mechanical or electronic lobing rates. 
 Most of the early workers considered an unfocused synthetic antenna. How- ever, Dr. Sherwin indicated that finer resolution should be achievable by using focusing because this technique removed what would otherwise be a restriction on the maximum length of synthetic antenna that could be used. 
 TION AND RELATED EQUATIONS AND THE GENERAL CHARACTERISTICS OF THE SUBSYSTEMS TRANSMIT 
        
 Óä°ÈÈ  2!$!2 (!.$"//+  4HESE PERFORMANCE ESTIMATION CURVES CAN BE USED TO SHOW EXTREMES IN 3.2 VARIATION   ANTENNA ELEVATION ANGLES REQUIRED  AND EXPECTED CLUTTER 
 The inﬂuence of different scintillation parameters is analyzed from the TFTPCF curves. Based on the reﬁned ACF in (11), the TFTPCF curves with different scintillation parameters are given in Figures 3–5, and Table 1presents the default value of irregularity parameters. (a)( b) Figure 3. 
 There have been a number of devices used as dispersive delay lines, or  pulse-compression filters, for linear FM waveforms. 16 They may be classed as ultrasonic,  electromagnetic, or digital. Ultrasonic delay lines include those of aluminum or steel strip,  piezoelectric materials such as quartz with propagation taking place through the bulk (or  volume) of the material, piezoelectric materials with the propagation taking place along the  surface (surface acoustic wave), and YIG (yttrium-iron-garnet) crystals. 
 In the  simplest case, the down-range error sdr is proportional to [ √2 cos (a /2)] −1 and cross- range error scr is proportional to [ √2 sin (a /2)] −1. *  Isorange contours intersect at other locations as well. These nontarget locations are called ghosts,  which must be  excised. 
 FED ALTERNATIVES ARE SOMETIMES USED#LASS "EAMWIDTH-INIMUM  $ISPLAY 3IZE#OAST 
 where r is the hair-power pulse width:·The· gaussfan-shaped pulse is sometimes specified in  those applications where interference with equipments operating at nearby frequencies is to be  avoided. The gaussian pulse is well suited for this purpose since its spectrum decays rapidly on  either side of the carrier frequency. Its rms range error is  . 
  ELIMINATES THE OPPORTUNITY FOR A SECOND 
 The acquisition scenario from the SPARX point of view is shown in Figure 10, while in Figure 11 the same scenario from the top view is shown. In both images the reﬂecting targets were highlighted in various colors to better distinguish them; in particular it is possible to recognize a paved road R (in yellow), various metallic poles P1, P2, P3, P4 and P5 (in purple) and some structures S1, S2 and S3 (in light blue). In range, all the relevant targets are located between 140 m (P1) and 450 m (S1), while in azimuth they are included between −35◦(P2) and +20◦(S3). 
 NOsaving intransformer weight isusually so v-..—____ .-..“’--xl FIG.14.2.—Eclipse NEA-7 dual-voltage generator. FIG.143.-General Electric dual-output gear box and generators for 3-phase a-c radar power and aircraft d-c supply. obtained, but thealternator islighter ormore reliable, and filters forthe higher ripple frequency are appreciably smaller and lighter. 
 SPEED DEPENDENCE DEFINED BY LINEAR REGRESSION ANGLE OF INCIDENCE      GRAZING ANGLE  AFTER ! ( #HAUDHRY AND 2 + -OORE  Ú )%%%   . £x°£{  2!$!2 (!.$"//+  .EVERTHELESS  THE IMPOSITION OF A POWER 
 AES–37, no. 4, pp. 1163–1175, October 2001. 
 J. P .. Jr .. 
 In this paper, an in-depth analysis of scintillation effect is performed on P-band sliding spotlight SAR. Based on the reﬁned TFTPCF model, the theoretical analysis indicate that the beam scanning and longer IPL will aggravate the signal decorrelation and make the sliding spotlight mode more sensitive to the ionospheric scintillation than stripmap mode. To accommodate the sliding spotlight geometry, a novel ReBP-based SAR-SS is proposed to generate the scintillation-contaminated SAR echo. 
 Thereafter, the tracking function provides data on range, range rate, and the two components of the line-of-sight inertia! rate. A digital guidance computer calcu- lates relative velocity perpendicular to the line of sight, using range and angular rate data. The closing component of velocity is obtained from the doppler or by differentiation of radar range measurements. 
 Afour-bitphaseshifter,forexample wouldgive1:100/OB=0.049. Smallsteering increments arepossible withquantized phaseshifters.Forexample, alinear arrayof100elements canbesteeredinincrements ofabout0.01beamwidth with3-bitphase shifters.82 8.9COMPUTER CONTROL OFPHASED-ARRAY RADARl16.121 Acomputer isanecessary partofaphased-array radar.Itisvitalinapplications where flexible,multifunction operations aredesired,asinsatellitesurveillance, airdefensesystems, ballisticmissiledefense,andmultifunction airborne radar.Thecomputer permitstheinherent flexibility ofanarraytobeexploited byefficiently controlling theradarandscheduling its operations. However, thecostofachieving thiscapability isnotinsignificant andhasbeenone ofthemajorfactorsinmakingthearrayradarexpensive. 
 The second property ofcavities that isimportant inmicrowave work istheir Q. Asinlumped-constant circuits, the value ofQisameasure ofthe sharpness ofthe resonance, and isdetermined bythe dissipative elements loading theresonant circuit. If~0istheresonant frequency and ~,and ~2arethe “half-power points,” —that is,thetwo frequencies, one above joand one below jo,atwhich thevoltage (orcurrent) inthecavity is0.707 asgreat asitisatresonance—then (5) Anequivalent, but somewhat more general, formula forQinvolves theamount ofelectromagnetic energy stored intheoscillating field within the cavity, and the rate atwhich energy isdissipated inthe walls orin any other way. 
 IEEE ,  vol. 53, pp. 822–833, August 1965. 
 16. R. Gangeskar and Ø. 
 If the target's relative velocity is not constant, a further widening of the received signal  spectrum can occur. If a, is the acceleration of the target with respect to the radar, the signal  will occupy a bandwidth  ( 3.3)  Ir, for example, a, is twice the acceleration of gravity, the receiver bandwidth must be approxi­ mately 20 Hz when the radar's wavelength is 10 cm.  When the doppler-shifted echo signal is known to lie somewhere within a relatively wide  band of frequencies, a bank of narrowband filters (Fig. 
 Triode and  tetrode grid-controlled tubes may be modulated by applying a low-power pulse to the grid.  Plate modulation is also used when the radar application cannot tolerate the interpulse noise  that results from those few electrons that escape the cutoff action of the grid.  The basic elements of one type of radar modulator are shown in Fig. 
 BASED PATTERN SOLUTION IS TO CALCULATE THE REFLECTOR FAR FIELDS  VIA A VECTOR INTEGRATION OF THE PRODUCT OF THE SURFACE CURRENT AND THE FREE SPACE 'REENS  FUNCTION 4HE MAGNETIC VECTOR POTENTIAL  ! IS DEFINED BY THE EQUATION  !*E DR RRJK R R  ` 
 A further development of the TEM horn is given by Martel21 in which  the antenna is composed of a set of spread “fingers” forming the shape of a horn as  shown in Figure 21.22. Each finger is a wire with a diameter of 1 mm and is resis - tively loaded at different locations along the length of the antenna. The feed compo - nent for the antenna is comprised of a 50 Ohm coax, feeding a tapered parallel plate  waveguide with a width of 30 mm and a height of 7 mm. 
 Some of  the papers using the term polarimetric  really refer to the use of just HH, VV , and HV  polarizations without regard for the phase. In this sense, they are using these images in  the way that like- and cross-polarized images have been used since the start of imaging  radars.167 Others, however, take full advantage of the full polarization matrix. One way to use the full matrix is to synthesize polarizations that either emphasize  or suppress particular classes of targets. 
 P.: Radar Height Finding, chap. 22 of" Radar Handbook," M. I. 
 When Sensitivity Time Control (which has a varying receiver gain  with range) is used with a long pulse and pulse compression, distortion can result in  the compressed pulse. It has also been said that solid-state transmitters are often less  efficient, they might be heavier, and their cost might be greater than an equivalent  vacuum tube radar system. The above have all been said at one time or another, but  there is not universal agreement about the importance of these characteristics for all  radar applications. 
 If a coherent radar is used, improved sensitivity and resolution can be obtained by using doppler filter banks or digital fast Fourier transform (FFT) processing. If the platform motion compared with the aperture length is sufficiently large, platform-motion compensation will be required.TRIPLE CANCELER PRIMARY RESPONSE SECONDARY RESPONSE PRIMARY AND SECONDARY RESPONSE, DOUBLECANCELERIMPROVEMENT FACTOR (dB) . Ship detection can be improved by rapidly scanning the antenna so that sea clutter is decorrelated and surface-target returns are integrated or leave a pattern of returns indicating their track. 
 M.: Bistatic and Multistatic Radar, chap. 36 in Skolnik, M. I. 
 For present  purposes. it suffices to state that a change in the applied d-c magnetic field produces a change  in the propagation properties because of a change in permeability, which results in a phase  shift.  A ferrite phase shifter is a two-port device that permits variation of the phase shirt between  input and output by changing the magnetic properties of the ferrite. 
 KNOWN &OURIER TRANSFORM OF A CONTINUOUS CONSTANT 
 J. S.: "Principles and Application:; of Random Noise Theory,'' John Wiley & Sons, Inc., New  York, 1958.  7. 
 TARGET DETECTOR -4$  USED A CLUTTER MAP FOR THE ZERO 
 Li32 has described experiments  using a 10-ft-diameter spherical reflector at a frequency of 11.2 GHz. The focal length was  29.5 in. If the phase error from the sphere is to differ from that of a paraboloid by no more  than A/ t 6. 
 PLED WITH hSPOTLIGHTINGv THE RADAR ANTENNA ON THE TARGET  RESULTS IN AN INCREASE OF THE RADARS DETECTION RANGE 3POTLIGHTING OR BURNTHROUGH MODES MIGHT BE EFFECTIVE  BUT A PRICE MUST BE PAID !S THE RADAR DWELLS IN A PARTICULAR DIRECTION  IT IS NOT LOOKING ELSEWHEREWHERE IT IS SUPPOSED TO LOOK )N ADDITION  THE BURNTHROUGH MODE IS NOT EFFECTIVE AGAINST CHAFF  DECOYS  REPEATERS  SPOOFERS  AND SO ON -ORE EFFECTIVE IS THE USE OF COMPLEX  VARIABLE  AND DISSIMILAR TRANSMITTED SIGNALS THAT  PLACE A MAXIMUM BURDEN ON %3- AND %#- $IFFERENT WAYS OF OPERATION REFER TO THE CHANGE OF THE TRANSMITTED FREQUENCY IN FREQUENCY 
 Several processing  ch24.indd   15 12/19/07   6:00:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 January. 1973.  104. 
 Moffett, C. E. Schenstcd, and I. 
 TO 
 7.4), the radiating element may be cho- sen to suit the feed system and the physical requirements of the antenna. For example, if the radiator is fed from a stripline phase shifter, a stripline dipole FIG. 7.1 Guided missile cruiser showing two out of four phased array antennas. 
 Transmissions are usu - ally non-overlapping in time to avoid a 6 dB increase in peak power and because most  radar transmitters are operated in saturation and simultaneous transmission at multiple  frequencies would produce significant transmitted intermodulation distortion. The sensitivity benefit of diplex operation for detecting Swerling 1 targets is shown  in Figure 6.23, increasing with probability of detection ( PD). For example, diplex oper - ation achieves 90% PD with 2.6 dB less total signal power than simplex. 
 pp. 290 -202. 1958. 
 Remote Sens. 2009 ,1, 266–277. [CrossRef ] 28. 
 the effective centerofradarrellection mayalsochange. Bothoftheseeffects-amplitude fluctua­ tionsandwandering oftheradarcenterofreflection-as wellasthelimitation imposed by receiver noisecanlimitthetracking accuracy. Theseeffectsarediscussed below. 
 B. L. Lewis, “Range-time-sidelobe reduction technique for FM-derived polyphase PC codes,”  IEEE Transactions on Aerospace and Electronics Systems , vol. 
 The triple canceler has a double-delay canceler tracking the primary spectra and a  single-delay canceler tracking the secondary spectra. The performance of the primary  system varies from that of a triple canceler to a level less than that of a double canceler.  The secondary-system performance varies from that of a triple canceler to a perfor - mance level lower than that of a single canceler. 
 240 CHAP. 8. RADAR BEACOhW. 
 OUTPUT FIG. 9.2 Principle of SLC operation (connection a only in the closed-loop im- plementation techniques). dimensional covariance vector R = E(VMV*). 
 Skinner, of Bristol, inspired their co-  workers by their insistence upon the need for centi-  metric waves, and by their own experimental skill. A  tremendous drive followed, until in July 1940 Professor  \ J. T. 
 Geosci. Remote Sens. 1999 ,37, 2192–2197. 
 Ê /  ÊÊ   Ê 1/1 Ê "1*  Ê{x 3IGNIFICANCE OF !PERTURE -ATCHING  !N ANTENNA IS A DEVICE THAT ACTS AS A TRANS 
 Azimuth Scan Rate .—Although therelation Smim - dazimuth scanning rate was notyetestablished atthetime ofthedevelopment here described, it was roughly understood; and itput ahigh premium onslow scanning rates. Mechanical problems inconnection with the antenna mount are greatly simplified byaslow scan rate. Strongly opposing these considerations isthe operational need for more complete and up-to-the-second information, inorder tofollow continuously the movement ofhigh-speed aircraft and tocontrol their movements intelligently. 
 radar left. Onbothradarstheanti-rainandanti-seaclutterdevicesareswitchedin.Thethreeshipsareclearlyvisibleonthe10cm.radarright.Thereareno targets visible on the 3 cm. radar left as the echo power has been absorbed by rain. 
 The dynamic range (peak sig- nal to rms noise) is limited to about 20 dB for a PPI display. Moving-Target Detector (MTD) Block Diagram. In the moving-target de- tector (MTD) the basic MTI principle, as described above, is enhanced by increasing the linear dynamic range of the signal processor, using a number of parallel doppler filters followed by constant-false-alarm-rate (CFAR) pro- cessing, and adding one or more high-resolution clutter maps to suppress point clutter residues. 
 These caused  “blackouts” on early 9 GHz systems—defined as an effective range of less than 1 mile.  As a consequence, the U.S. favored operation at 3 GHz. 
 86.Taylor,T.T:DesignofCircular Apertures forNarrow Beamwidth andLowSidelobes, IRETraIlS., vol.AP-8,pp.17-22,January, 1960. 87.Hansen, R.c.:TablesofTaylor Distributions forCircular Aperture Antennas, IRETrailS., vol.AP-8,pp.23-26,January, 1960. 88.Bayliss, E.T.:DesignofMonopulse Antenna Difference Patterns withLowSidelobcs, BellS}'stem Tech.J.,vol.47,pp.623-650, May-June, 1968. 
 8and 10ofComponents Handbook, Vol. 17ofthisseries. *War Department Technical Manual TM-1524.. 
 SIVE WEAPON SYSTEMS FOR A CONSIDERABLE TIME 4HEREFORE  ONLY THE USE OF RELATIVELY LOW 
 In early MTI systems, the IF lim - iter served the purpose of deliberately restricting the dynamic range to reduce clutter  residues at the MTI output. The received signals are then converted into in-phase and  quadrature components (I & Q) through the A/D converter, either using a pair of phase  detectors or through direct sampling as discussed in Section 2.13. The in-phase (I) and  quadrature (Q) outputs are a function of the amplitude and phase of the IF signal and  FIGURE 2.3  MTI system block diagram I QTRANSMITTERWAVEFORM GENERA TOREXCITER RECEIVERIF LIMITER VIDEO OUTPUTTIMING & CONTR OLLNADUPLEXER MIXERANTENNA A/D CONVER- SIONMAGNI- TUDEVIDEO INTE- GRATORTΣ+− TΣ+ − MTI FIL TER ch02.indd   4 12/20/07   1:42:45 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 no. 75  Cfi0 938-1 AES.  87. 
 MUM 
 FEED REFLECTOR IMPLEMENTATIONS  FLARED WAVEGUIDE HORNS ARE THE MOST COMMON 4HE FEED IN CONJUNCTION WITH THE REFLECTOR  MUST ALSO SATISFY THE ANTENNA POLARIZATION REQUIREMENTS AND HANDLE REQUIRED PEAK AND AVERAGE POWER LEVELS UNDER ALL OPERATIONAL ENVIRONMENTS /THER FEED DESIGN CONSIDERATIONS INCLUDE THE OPERATING BANDWIDTH AND THE POTENTIAL IMPLEMENTATION OF ANY ADDITIONAL MODESPATTERNS  EG  DIFFERENCE OR SQUINTED BEAMS &OR SINGLE 
 TO 
 Infiguring ripple itisusually satisfactory toassume aconstant rectifier drain equal totheaverage current required bythepulser. The ripple must bekept below that which would cause achange inmagnetron current sufficient toproduce either amode shift orundue frequency modulation. Apart from thk consideration, amplitude modulation is. 
 Shaw and S. C. Pohlig, “I/Q baseband demodulation in the RASSP SAR benchmark,”  Project Report RASSP-4, Massachusetts Institute of Technology, Lincoln Laboratory, 25 August  1995, http://www.ll.mit.edu/llrassp/documents.html. 
 SCALE CURVATURE MIGHT INTRODUCE AN ORGANIZING PRINCIPLE FOR THE MANY BITS AND PIECES THAT PRESENTLY MAKE UP THE THEORY OF SEA SCATTER )N THE LAST EDITION OF THIS (ANDBOOK    THE FINAL STATEMENT IN THIS CHAPTER WAS  h)T WILL BE INTERESTING TO SEE WHAT PROGRESS WILL HAVE BEEN MADE IN THE THEORY OF SEA CLUTTER BY THE PUBLICATION OF THE NEXT EDITION OF THIS HANDBOOKv )T APPEARS THAT THE ANSWER ISNOT MUCH "UT THERE IS SOME EVIDENCE THAT THE THEORY OF SEA SCATTER IS  GRADUALLY BEING FREED FROM THE PARALYZING MONOTHEISM OF "RAGG SCATTER  SO THERE IS  HOPE FOR THE FUTURE , 
 H.W.:AnImproved Simultaneous PhaseComparisOl1 Guidance Radar.IRETrans.•vol. ANE-3, pp.67-70,June,1956. 2R.Haus7.,W.•andR.A.Zachary: Phase-Amplitude Monopulse System,IRETrans.,vol.MIL-6, pp. 
 A  separate a posteriori probability is computed for each hypothesis. That hypothesis which  results in the largest a posteriori probability is selected as the most likely to explain the event.  This method has been applied by Woodward and Davies to the reception of signals in  noise.26-28 It is based upon the application of Bayes' rule for the probability of causes.29 The  joint probability of two events x and y is  p(x, y) = p(x)p(yjx) = p(y)p(xjy)  where p(x) and p(y) = probabilities of events x and y, respectively (10.22)  p(y Ix)= conditional probability that event y will occur, given that event x has  occurred  r,{y I,.) -r()nrlitinnnl nrnhnhilitv nf PVPllf Y P-ivf"'n ffrnt ,. 
 RESPONDING SQUARE OF THE SURFACE CURVATURE BELOW B  7AVE 
 DIFFERENCE ESTIMATION PROCEDURE IS BEST WHEN MODERATE 4AYLOR WEIGHTING FUNCTIONS ARE USED &OR UNIFORM WEIGHTING  THE PROCEDURE WOULD BE SUBSTANTIALLY INFERIOR TO THE MAXIMUM LIKELIHOOD APPROACH 4HE INCREASE IN THE CONSTANT  K FOR THE MORE SEVERE WEIGHTING CASES IS THE  RESULT OF THE 3.2 LOSS RESULTING FROM THE USE OF WEIGHTING 5SING AN APPROACH SIMILAR TO THAT USED TO RESOLVE THE RANGE AMBIGUITY  ALL POSSIBLE  RADIAL VELOCITIES ARE THEN ENUMERATED TO THE MAXIMUM NEGATIVE AND POSITIVE RADIAL VELOCITY OF INTEREST ON EACH OF THE #0)S  }}         M AX MAX 6VM 6 M M MII " I   
   PP n     2 !NDRAKA  h! SURVEY OF #/2$)# ALGORITHMS FOR &0'! 
 The better action is to take steps to correct loss in operator performance rather  than tolerate it by including it as a loss factor in the radar equation.  Field degradation. When a radar system is operated under laboratory conditions by engineer-  ing personnel and experienced technicians, the inclusion of the above losses into the radar  equation sllould give a realistic description of the performance of the radar under normal  corlditioris (ignoring anomalous propagation effects). 
 24-29, November 1982. 7. Williams, F. 
 K.: "Modern Radar System Analysis," Artech House, Norwood, Mass., 1988, pp. 121-123. 106. 
 Ifrearward vision isnotrequired, anantenna with circular scan canbemounted just behind and below thenose oftheairplane, where theradome can becompletely faircd in. Scanning ofonly aforward sector ispossible iftheantenna ismounted inthenose. Such alocation isimpossible insingle-engine airplanes, and external housing becomes necessary. 
 15.14] DETAILED DESIGN OF THE ANjAPS-10 619 pressure pump. The weight, power consumption, and size ofthe units aresummarized inTable 15.1. Table 15.2 gives more detail onthe design ofthevarious units. 
 Burkett, and J. R. Duncan: Upwind-Downwind-Crosswind  Sea-Clutter Measurements, Naval Research Laboratory Report 6881, Washington, D.C., Apr. 
  OR FOUR 
 Lee, “An array-fed, dual-reflector antenna system (of offset confocal  paraboloids) for satellite antenna applications,” IEEE Symp. Antennas Propag ., pp. 1586–1589,  1989. 
 Asuccessful flight test ofa working “breadboard” model ofanairborne radar intended forAIuse was made onMarch 10,inaB-18A furnished bythe Army Air Corps. Inthis fight itwas found that theequipment was extremely effective in searching forships and surfaced submarines atsea. Inthe late spring of1941, anexperimental microwave sea-search radar equipped with aPPI was installed onthe olddestroyer U.S.S. 
 Atmos. Ocean. Technol., vol. 
 Although this frequency region is of large extent,  most of the interest in millimeter wave radar has been in the vicinity of 94 GHz  where there is a minimum (called a window ) in the atmospheric attenuation.   (A window is a region of low attenuation relative to adjacent frequencies. The win - dow at 94 GHz is about as wide as the entire microwave spectrum.) As mentioned  previously, for radar purposes, the millimeter wave region, in practice, generally  starts at 40 GHz or even at higher frequencies. 
  KLYSTRON  EXCEPT THAT THE 6! 
 G. W. Ewell, “Techniques of radar reflectivity measurement,” Chapter 7 in Bistatic Radar Cross- Section Measurements , 2nd Ed., N. 
 IZED APPLICATION 
 Therefore, the results previously derived for a gaussian clutter spectrum can be readily applied.  Equations 4.25 and 4.26 derived for the clutter fluctuation improvement factor apply for the  antenna scanning fluctuations by proper interpretation of a,, the standard deviation, or the  rms spread of the frequency spectrum about the mean.  The voltage waveform of the received signaJ is modulated by the square of the antenna  electric-field-strength-pattern, which is equal to the (one-way) antenna power pattern G(O),  described by the gaussian function as  ( 2.77682 ) G(8) = G0 exp -Di (4.29)  Since the antenna is scanning at a rate of tJ. 
 TIME 34!0 CAN IMPROVE THE FINAL IMAGE QUALITY u &REQUENCY AGILITY 3!2 PROCESSING NEEDS PHASE COHERENCE FOR OBTAINING THE SYN 
 TIONAL FEEDS 4HE PHASE SHIFTER MUST BE RECIPROCAL SO THAT THERE IS A NET CONTROLLABLE PHASE SHIFT  AFTER PASSING THROUGH THE DEVICE IN BOTH DIRECTIONS 4HIS RULES OUT FREQUENTLY USED NONRECIPROCAL FERRITE OR GARNET PHASE SHIFTERS #ONSTRAINED &EEDS  4HE OPTICAL 
 The modulator, type 64, provided a 3.3 kV pulse which was applied to a pulse transformer in the TR, providing 10 –15 kV to the magnetron. The output of the magnetron was fed by coaxial cable to the waveguide feed of the scanner. Figure 3.2. 
 V  WOULD BE PROPORTIONAL TO INPUT SIGNAL AMPLITUDE 3PURIOUS AT ZERO DOPPLER  IS NOT DUE TO DC OFFSET IT IS THE RESULT OF EVEN 
 The choice of  range as the independent variable may seem artificial, but it is a useful approach for  performance examination. With these curves, the impact on radar SNR performance  can be estimated for selected antenna gain patterns, transmitted powers, target RCS,  and coherent integration times (CIT). Figure 20.30 is an example for January with moderate solar activity, SSN = 50, in  daytime. 
 AES-IO. pp. 25-33, January, 1974. 
 SHARPENING RATIO  DIFFERENT AMOUNTS OF PRESUMMING MUST BE USED FOR EACH BEAM POSITION  0RESUMMING  IS THE FORMATION OF AN UNFOCUSSED SYNTHETIC BEAM IE  THERE IS LITTLE OR NO ATTEMPT TO MATCH THE EXACT PHASE HISTORY OF  SURFACE POINTS  INSIDE THE REA L ANTENNA BEAM BY WHAT  IS ESSENTIALLY A LOWPASS FILTER 4HIS WOULD RESULT IN DIFFERENT TARGET BRIGHTNESS AND CON 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar.  TRACKING RADAR  9.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 The ratio was pushed to a very minimum of about 3 to obtain servosystem bandwidth  of the specified 3.5 Hz. A smaller radar with a 12-ft dish, for example, can provide a  servosystem bandwidth up to 7 or 8 Hz with conventional design. 
 bonded Au contacts lnterdigital  electrode  transducers  Figure 11.16 Schematic of a simple surface  acoustic wave (SAW) delay line. (From  Bristol, 22 Courtesy Proc. IEEE.) . 
 K. L. Felch et al., “Characteristics and applications of fast-wave gyrodevices,” Proc. 
 FREQUENCY COMPONENTS AS SHOWN IN THE FINAL GRAPH ON THE RIGHT  4HE DESIRED SAMPLED  COMPLEX ENVELOPE REPRESENTATION HAS NOW BEEN REALIZED  BUT AT THE ORIGINAL SAMPLING RATE OF F !$ )F DESIRED  THE OVERSAMPLING CAN FINALLY BE REMOVED THROUGH DECIMATION  BY A FACTOR OF  AS SHOWN IN THE LAST STEP IN THE FIGURE&)'52%  )MPLEMENTATION OF !$ CONVERSION USING DIRECT SAMPLING OF THE )& SIGNAL  
 CORRELATED SIGNAL #ONTROL OF THE CROSS 
 The damping network reduces the trailing edge of the pulse and prevents  post-pulse oscillations which could introduce noise or false targets.  Hsrd-tube rn~dulator.~ The hard-tube modulator is essentially a high-power video pulse  amplifier. It derives its name from the fact that the switching is accomplished with " hard-  vacuum" tubes rather than gas tubes. 
 It was realized by the NRL experimenters that higher radar frequencies were desired,  especially for shipboard application, where large antennas could not be tolerated. However,  the necessary components did not exist. The success of the experiments at 28 MHz encouraged  the NRL experimenters to develop a 200-MHz equipment. 
 197-213, June,  1955.  41. McKee. 
 M. Glover: Applications of Radar to Meteorological Opera­ tions and Research, Proc. IEEE, vol. 
 TIME MONITOR OF WHAT IS EXPECTED UNDER THE PREVAILING CONDI 
 TERN IN THE CROSS 
 usuallyattheoutputoftheIFamplifier beforethenonlinear seconddetector. Thereceiver bandwidth BnisthatoftheIFamplifier inmostreceivers. Theavailable gainGois theratioofthesignaloutSotothesignalinSj,andkToBnistheinputnoiseNjinanideal receiver. 
 PLE  PRESENTLY AVAILABLE AS VERSION )2) 
 Sirice the fixed error is due to the discrete nature of the frequency counter, its effects can  he reduced by wobbling tlie modulation frequency or the phase of the transmitter output.  Wobblirlg the transmitter phase results in a wobbling of the phase of the beat signal so that an  average reading of the cycle coutiter somewhere between N and N + 1 will be obtained on a  riormal meter rhovement. In one altimeter,jO the modulation frequency was varied at a 10-Hz  rate. 
 Receiver  protectors also serve to protect against power reflected by mismatches at the antenna.  Ferrite limiter. The ferrite limiter46 followed by a diode limiter, has also been eruploycd as a  solid-state receiver protect~r.~~*~~ The-diode is necessary to reduce the spike leakage to a safe  level since the ferrite acting alone does not offer sufficient suppression of the spike leakage at  high peak power. 
 Scanning can be in the form of phase scanning or beam switching, or multiple simultaneous beams may be used on receive with a wide antenna pattern on transmit. Many systems of this type have been devel- oped for both naval and land-based use (Sec. 7.11). 
 3. Signal Processing The signal model was built and the proposed method for suppressing azimuth sidelobes was derived based on the imaging geometry described in Section 2. It contained four main steps: 2D focusing, image registration, elevation processing, and incoherent addition, as indicated in Figure 2. 
 Both the transmitted signal and the returned signal are periodic waves, as is their difference. Hence there cannot be a continuum of dif- ference frequencies; there can be only harmonics of the fundamental modulation fre- quency. Diagrams such as Fig. 
 It is used by SPASUR12 as a brute-force, satellite location technique. However,  because of the large aperture sizes (or array lengths) required for sufficiently accu - rate DOA measurements at useful ranges, triangulation is seldom considered for  other applications. Concepts, data, and expressions developed for bistatic radars often apply to multi - static radars, for example, the range equation, target doppler, target radar cross section,  and surface clutter. 
 A filter can be used to exclude the  clutter but pass the target echo. Similarly, if the targets are receding from one a not her along  headings 180° apart, the target doppler frequency shift will again lie outside the clutter spec­ trum and may be readily separated. from the clutter energy by filters. 
 under the action of the crossed electric alid  rliag~lctic fields. fo1.111 illto rotating electrori (space-charge) bu~icties, or spokes. These bunclles  drift alorig tlie slow-wave circuit it1 phase with the RF signal and transfer energy to the KF  lvavc to provide aniplificatio~i. 
 Typical dimensions (radiuses) of white dwarfs which pulsate with period τ=1 s, and neutron stars with pulsation period 10−2s are in the interval (1−5)×106m[1]. The pulsar can be considered as a massive freely spinning top and a powerful particle accelerator since the rotating magnetic field generates enormous electric fields that accelerate charged particles. These accelerated particles emit electromagnetic waves at spin frequency (across the spectrum, from radio waves to gamma-rays). 
 Wodward-Levinson method. Another method of approximating the desired antenna pattern  with a finite aperture distribution consists in reconstructing the antenna pattern from a finite  number ofs9,mpled values. The principle is analogous to the sampling theorem of circuit theory  in which a time waveform of limited bandwidth may be reconstructed from a finite number of  samples. 
 With a single-sided planar mirror, the two time intervals  between observations correspond to the time· it takes for the planar mirror to rotate !th and  Jth of a revolution. If the mirror is double-sided, the times between observations correspond to  ijlh and ith of a revolution.  Three renectors can be used instead of four to produce a uniform target observation rate. 
 Meas. 1996 ,45, 948–954. [ CrossRef ] 17. 
 14.8. The considerable improvement since 1970 in crystal-oscillator multiplier *The adjective residual sometimes appears in the literature. It is not an apt choice in radar, where the source is usually the element that sets the phase-noise floor. 
 217-223.  157. Ward, H. 
 When existing waveforms must be used, this can present challenges. Existing  aperture scheduling algorithms can then allocate time for transmission or reception.81 To achieve very high throughputs, phase linearity in transmit and receive paths  is critical since data transmission waveforms rely on modulation that is every bit as  complex as many radar modes. This can also impact choice of taper function because  angular variations in phase across the main-beam wavefront may incur performance  penalties. 
 Accordingly, airborne or spaceborne WAS radar is widely applied in civilian and military ﬁelds [ 3–7], and Doppler beam sharpening (DBS) technique is a very e ﬀective tool to accomplish the WAS ability [ 8–11]. However, the large surveillance region in WAS radar is at the expense of low cross-range resolution. The low cross-range resolution limits its further application. 
 WARD OF THE BOUNDARY WHERE THE %ARTHS GEOMAGNETIC FIELD LINES CHANGE FROM CLOSED CONNECTED TO THEIR IMAGES IN THE OPPOSITE HEMISPHERE  TO OPEN  THAT IS  CONNECTED TO THE INTERPLANETARY MAGNETIC FIELD ! WIDE VARIETY OF PLASMA WAVES AND INSTABILITIES POPULATE THESE REGIONS  PRODUCING IRREGULARITIES THAT ACHIEVE HIGH ELECTRON DENSITIES AND HENCE  PROVIDE STRONG SOURCES OF SPREAD 
 September. 1961 100.Crispin,J.W.,Jr.,andK.M.Siegel:..Methods ofRadarCross-Section Analysis." Academic Press, Inc.,NewYork,1968,chap.7. 101.Graf,G.:OntheOptimization oftheAspectAngleWindows fortheDoppler Analysis oftheRadar ReturnofRotating Targets,IEEETrans.,vol.AP-24,pp.378-381. 
 The  Moving Target Detector, described in Sec. 4.7, is an example of an MTI radar designed  specifically to cope with the special problems or precipitation clutter.  Polarization. 
 M SURFACE HEIGHT ERROR  WHICH IS UNACCEPTABLE IF CM 
 BAND 4WYSTRON HAS A BANDWIDTH OF  WITH  A  EFFICIENCY   D" GAIN AT MIDBAND  PEAK POWER OF  -7   AND AVERAGE POWER  OF  K7  %XTENDED )NTERACTION +LYSTRON %)+   )N THE %)+  THE SINGLE 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°Ó£ 3!2 SYSTEMS AS A RULE DO NOT IMPLEMENT IMAGE FORMATION ONBOARD FOR SEVERAL REASONS   INCLUDING HIGH DATA RATES 0ROCESSING FROM RAW 3!2 DATA TO IMAGERY INCREASES DATA VOLUME SUBSTANTIALLY  THUS INCREASING THE DOWNLINK DATA TRANSFER BURDEN 0ERHAPS MORE PERSUASIVE  ONCE PROCESSED INTO DETECTED IMAGES  THE OPTIONS ARE LIMITED FOR SPECIAL 
 (a)ȱ (b)ȱ Figure 7. Comparison of ( a) the simulated SAR eddy image and ( b) the ENVISAT-1 ASAR image under the same radar parameters and wind ﬁeld conditions. The radar look and wind direction are indicated by black arrows. 
 It also subtracts the output of the top pair from the output of the bottom pair to sense any unbal- ance in the elevation direction. The Fig. 18.8 comparator is the circuitry which performs the addition and sub- traction of the feedhorn outputs to obtain the monopulse sum and difference sig- nals. 
 D. Brown, D. N. 
 The transmitting oscillator (LO for Local Oscillator) is added on the tran s- mitting end and is again taken out at the  receiving end.  In comparison to the Doppler fr e- quency, which can be measured, both oscillators must be sufficiently stable for the entire time.  In Figure 8.5, an example of coherent pulse Radar, a quadrature modulator is employed to  additionally determi ne the direction of the target movement. 
 Resolution is possible since each element of the distributed target has a different relative  velocity. This principle has been used in synthetic aperture radars for ground mapping, inverse  SAR for SOI and the imaging of planets, and in the scatterometer for measuring the ground or  sea echo as a function of incidence angle.  Internal motions of the target such as the rotation of aircraft engines, vibrations of vehi­ cles, the spinning of a satellite, or the rotation of antennas can also provide information abou!  the target. 
 (11.1) to compute the RCS. Equation (11.2) and the two-dimensional coun- terparts of Eqs. (11.9) and (11.10) must be used for two-dimensional geometries, of course. 
 The primary advantage of the two-beam system is a reduction in equipment. However, the  accuracy is not as good as with systems using three or four beams.  In principle, the CW radar would seem to be the ideal method of obtaining doppler­ navigation information. 
 The operator then switched toheight-finding, turned thegoniometer again and pressed abutton, whereupon theheight was displayed infront oftheteller. If theheight measurement was ambiguous orunreliable, that fact was shown bythe machine, and the operator could try again onthe “B” height system. Operational useofradar information isdiscussed inChap. 
 The bearing angle to the radar target may also be measured in a  clockwise direction from the centerline of your own ship or aircraft and is referred to as the relative  bearing .  The ra pid and accurate transmission of the bearing information between the turntable with the  mounted antenna and the scopes can be carried out for    servo systems and    counting of azimuth change pulses.     Servo systems are used in older radar antennas and missil e launchers and works with help of  devices like synchro torque transmitters and synchro torque receivers. 
 Remote Sens. 2017 ,55, 159–172. [ CrossRef ] 26. 
 182. S. J. 
 The second graph uses components of the  received signal that are orthogonal  to the transmitted signal. Figure 16.46 gives a widely quoted example of this type of display for images of  San Francisco.166 The axes in the horizontal plane are the orientation angle for the  synthesized transmitted signal yt and its ellipticity angle ct. The vertical axis is relative  power. 
 The price will be crucial for the future.  The  lenses are excited by patch -antennas (λ/2 emitter) or by diel ectric shaft emitter.  The polariz a-. 
 Processing of circular SAR trajectories with fast factorized back-projection. In Proceedings of the 2011 IEEE International Geoscience and Remote Sensing Symposium, Vancouver, BC, Canada, 24–29 July 2011; pp. 3692–3695. 
 The main-beam clutter region, located at  f0 + (2VR/l)cos(y0), contains the strong return from the main beam of the antenna TABLE 4.3  Typical Values for an X-band (10 GHz) Airborne Fire-Control Radar Pulse Doppler Waveform PRF Transmit Duty Cycle Medium PRF   10 −40 kHz  5−10% High-medium PRF  60−100 kHz 10−20% High PRF 120−300 kHz 15−50% FIGURE 4.1  Clutter and target frequency spectrum from a horizontally moving platform ch04.indd   4 12/20/07   4:51:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 As a spacecraft, Geosat  was one of the few Earth-observing  missions to rely on the purely passive  gravity-gradient means of attitude con - trol,74 as evidenced by the extended  (vertical) boom in Figure 18.9. The  attitude was stable to less than 1 °, to  which the altimeter’s pulse-limited  range measurement was robust. Geosat Follow-On (GFO). 
 I'roc,. IEEE. vol. 
 Hydraulic Eng. 2014 ,45, 171–179. 48. 
   
 [ CrossRef ] 13. Alpers, W.; Brandt, P .; Lazar, A.; Dagorne, D.; Sow, B.; Faye, S.; Hansen, M.; Rubino, A.; Poulain, P .M.; Bremer, P . A small-scale oceanic eddy off the coast of West Africa studied by multi-sensor satellite and surface drifter data, and by a numerical model. 
 The radar is instrumented to a range of 240 nmi and operated with six PRFs averaging 250 Hz. The receive beams in the stack are 1.1 in azi- muth and variable in elevation beamwidth in such a way that the six span the 20° of total elevation coverage. Subsequent versions of the radar provided pulse compression and improved MTI waveforms and processing.13 The AN/TPS-75 is an upgraded version of this radar with a planar array low-sidelobe antenna. 
 B. fl.. and D. 
 68. Urkowitz, H.: Analysis and Synthesis of Delay Line Periodic Filters, IRE Trans., vol. CT-4, pp. 
 la Radar cross section (square meters) of the T-3866  Head-on aspect ( ± 1.0 degree)  x,.,. X I.R Svv Lvv  Percentile 20 50 80 20 50 80 20 50 80 20 50 80  Landing  gear up 0.33 0.83 l.7 0.21 0.53 1.2 1.6 3.1 4.7 1.5 1.8 2.2  Landing  gear extended 0.53 J .6 3.5 0.24 0.80 2.1 1.1 2.3 4.4 0.99 2.6 4.5  Table 2.lb Median cross section (X ,.,_) for aspects near nose-on  Azimuth angle (degrees) Azimuth angle (degrees)  Elevation Elevation  angle 0 2 5 7 angle 0 2 5 7  () lUn 16 0.72 0.45 0.90 1.2  (i 0.68 0.61 0.99 0.82 18 . 0.43 0.44 1.3 0.84  8 1.2 0.94 1.7 2.2 20 0.43 0.52 0.63 0,64  10 1.4 1.6 :u I .4 22 0.45 0.66 l.l l.1  12 U.70 1.0 1.6 2.1 24 0.65  14 0.79 0.60 0.63 1.5  Xu.: Transmit left circular polarization, receive left circular (X band). 
 IIF radar equation. The simple 0TH radar equation of Eq. (14.22) does not account for the  fact that a surveillance radar must cover a specified angular sector in a specified time. 
 18.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 offered an advantage when attempting to distinguish new ice from calm sea at C band  and moderate incidence. The applications diversity implied a span of preferred inci - dence from ∼20° to more than 50 °. In response, the antenna was required to steer its  beam in elevation, which evolved into seven different standard elevation beam pat - terns, electronically steered and shaped. 
 BAND NATIONAL ASSET 3!2 FLEET  INCLUDING 4EC3!2  )SRAEL  AND THE )'3 
 or turbulent air can also average out the fixed error provided the time  constant of the indicating device is large compared with the time between fluctuations. Over  smooth terrain, such as an airport runway, the fixed error might not be averaged out. Note that  even if the fixed error were not present, the accuracy with which the height can be measured  will depend on the signal-to-noise ratio, as discussed in Sec. 
 Barrick. D. E .. 
 Good design is based on maximizing the ratio of the signal energy to noise  power per hertz (EIN,), as well as employing techniques to reduce mutual interference. It is  important to avoid receiver saturation, or overloading. A wide dynamic range is desired. 
 The gain of a uniformly illumi- nated and lossless aperture of area A, with a broadside beam, is G(0) = 4irA/X2. With a nonuniform aperture distribution and with losses present, the gain is re- duced by the efficiency term r\ to G(O) = 4v-2T] (7.17) A. If the aperture is considered as a matched receiver, then the amount of energy arriving from a direction G0 is proportional to its projected area. 
 N. Chrisman and C. A. 
 363-374. 24. Ringel, M. 
 CAL MISSILE IN &IGURE  IS ITS EXHAUST DUCT AT THE REAR  BUT JET INTAKE DUCTS BEHAVE MUCH THE SAME WAY 4HE ECHOES FROM CAVITIES SUCH AS INTAKE DUCTS  EXHAUST DUCTS  AND COCKPITS ARE LARGE AND TEND TO PERSIST OVER ASPECT ANGLES AS WI DE AS n OR n 4HIS IS  BECAUSE MOST OF THE INTERNAL DUCT SURFACES IE  COMPRESSOR STAGES AND TURBINE FACES   ARE METALLIC  AND ANY RADAR WAVE THAT FINDS ITS WAY INTO THE STRUCTURE WILL LIKELY FIND  ITS WAY BACK OUT TOWARD THE RADAR 4HIS IS ALSO TRUE OF INTERNAL REFLECTIONS FROM WITHIN COCKPIT CANOPIES 3PECULAR 3CATTERERS  ! SPECULAR SCATTERER IS ANY TARGET SURFACE THAT IS ORIENTED PER 
 KNOWN  COSECANT 
 Relationships between threshold levels, probabilities of  detection and false alarm, signal-to-noise ratio, and number of pulses integrated were obtained  using as a model a receiver with the following characteristics: (1) the envelope of the receiver  noise at the output of the IF filter was described by the Rayleigh probability density function  (pdf); (2) the envelope detector had either a linear or a square-law characteristic; (3) the  integrator consisted of a linear addition of the pulses in the video portion of the receiver; and  RADAR CLUTIER 485 madetodecorrelate thetwopulsesreceived fromatargetwiththehigh-speed rotation rateby transmitting eachofthetwopulses'a{ adifTerentfrequency.Unex.pectedly, nodiscernible improvement wasnotedwhenthetwofrequencies wereusedinsteadofasinglefrequency, even thoughthetwofrequencies were60MHzapart.Thiswouldindicate thatthereisaslowly fadingcomponent oftheclutterechowhichcannotbedecorrelated andisprobably similarto theclutterspikesdiscussed inSec.13.3. Thedecorrelation timeoftheclutterisapproximated bythereciprocal ofthewidthofthe clutterdoppler spectrum. Itisfoundthatthewidthorthefrequency spectrum decreases with decreasing frequency sothatthedecorrelation timeisgreateratthelowerfrequencies thanat thehighfrequencies. 
 Remote Sens. 2015 ,7, 1540–1564. [ CrossRef ] 34. 
 Inthe forward-bias (conducting) state,whenappreciable currentispassed,theinjection ofholesand electrons fromthePandNregionsrespectively, createsanelectron-hole plasmainwhatwas formerly thedielectric region.Theslightlylossydielectric ischanged toafairlygoodconduc­ torwiththeapplication offorward bias.Thecapacitive component ofthecircuitdisappears andtheequivalent circuitbecomes asmallresistance whichdecreases invaluewithincreasing forward current.Theresistance canvaryfromthousands ofohmsatzerobiastoafraction of + Intrln~iC{ regIOn conducting Forward stale Forward-bias resistance Package inductance}lntrinsiC region dielectric + Reverse state MJUnCliOn capacitance ~paCkage capacitance Back-bios resistanceFigure8.9PINdiodesandsimplified equivalent circuitsforforwardandreversestates.. at1 ohm with tetis of triilliatnperes bias currerlt. 1-llus with forward bias the diode resembles a  low-value resistor. 
 At any slant range r, the diameter of the region scanned is r cos a, and the height of the measurement is r sin a, where a is the elevation angle (see Fig. 23.5). If p is the azimuth angle, Vh is the horizontal wind speed, and Vf is the fall speed of the particles, the radial velocity at range r is given by yr(p) = vh cos p cos a + Vf sin a (23.50) FIG. 
 It is computed by assuming a uniformly distributed target doppler over one filter spacing and is a function of the FFT sidelobe weighting. Amplitude-Weighting Loss. This loss results from the increased noise band- width of the doppler filters that occurs because the filter sidelobe weighting. 
 For that purpose, the target is ascribed  an effective area called the radar cross section , or RCS. The RCS is the projected area  of a metal sphere that would return the same echo signal as the target, had the sphere  been substituted for it. Unlike the echo of the sphere, however, which is independent of the viewing angle,  the echoes of all but the simplest targets vary significantly with orientation. 
 /6 
 TO 
 This invention, with its limitless applications in the  air and at sea, was born simultaneously with the accession  ‘to power of the Nazi party in Germany. Had British  scientists not been working upon this invention long  before Europe burst afresh into the flame of war it is  .very doubtful indeed whether we in these islands would  have been able to hold out in the critical times of our  lonely struggle in 1940-41. From those grim war years  ‘radar has risen from the obscurity of an untested  iscientific trick of unknown operational value to a peace-  time system in which radio is used in a diversity of ways  as a navigational aid. 
 The elevation angle of the target corresponds to the elevation readout on the antenna mount. In early radar systems employing this technique, an op- . (b) FIG. 
 24.12 GROUND-WAVE RADAR PERFORMANCE Ground-wave propagation as defined here will include all but sky-wave paths. That is, the paths or illumination considered are direct line-of-sight and by sea- Range (nmi) FIG. 24.28 Curves for estimating ground-wave radar performance are given as a function of range and are parametric in frequency. 
 This discussion has not considered the electromagnetic and magnetic loss tangent,  and these may need to be considered in special cases. It can be seen from the above expressions that the attenuation constant of a mate - rial is, to a first order, linearly related (in dBm–1) to frequency. It is not sufficient to  consider only the low frequency conductivity when attempting to determine the loss  tangent over the frequency range 107 to 1010 Hz. 
      
 22.24  22.5 Critical Issues  .........................................................  22.26  SBR System Costs  ............................................  22.26 Survivability and Vuln erability  ............................ 
 NIFICANT 4HE MAJOR BENEFIT OF A PHASED ARRAY WITH RESPECT TO TRACKING IS IN THE AREA OF  TRACK INITIATION   0HASED ARRAYS USE A CONFIRMATION STRATEGY TO INITIATE TRACKS RAPIDLY  4HAT IS  AFTER THE ASSOCIATION PROCESS  ALL UNASSOCIATED DETECTIONS GENERATE CONFIRMATION DWELLS TO CONFIRM THE EXISTENCE OF A NEW TRACK 4HE INITIAL CONFIRMATION DWELL USES THE SAME WAVEFORM FREQUENCY AND 02&  IF A PULSE 
 Andrews14 has developed an optimization procedure for platform-motion compen - sation that rotates the phasors directly rather than by using a quadrature correction. The  procedure determines the antenna feed coefficients for two compensation patterns, one  of which, C1(q ), is added to the sum pattern Σ(q ) and fed to the undelayed canceler  FIGURE 3.17  Sum and difference patterns used to determine DPCA performance ch03.indd   19 12/15/07   6:03:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Barton, CW and Doppler Radars,  Section VI-2, Vol. 7. Norwood, MA: Artech House, Inc., 1978,  pp. 
 17.8. Atthetransmitter themaster pulse triggers asquare-wave generator (flip-flop a)which switches a shock-excited oscillator (Fig. 13.41). 
 , n -ODERATEn(IGH *4)$3 , n -ODERATE *4)$3 ,%4 , n  -ODERATE *423 6(& 
 SWEEP FALSE 
 WHILE 
 WAY  TRANSMISSIONS FROM POWERFUL RADIO STATIONS AROUND THE WORLD  AS DISCUSSED IN THE PREVIOUS SECTION )MPERFECTIONS IN THE RECEIVER RESULT IN SOME OF THIS .   (& /6%2 
 RESOLUTION RADAR (IGH RESOLUTION CAN BE OBTAINED IN THE RANGE  ANGLE  OR DOP 
 The current literature is quite large; and, because of the limitations of -space, only a much  smaller proportion of what is available could be cited.  In addition to changes in radar technology, there have been changes also in style and  nomenclature. For example, db has been changed to dB, and Mc is replaced by M HL. 
 RANGE DOMAIN MUST BE PERFORMED OFFLINE IN  THIS EXAMPLE 4HE FAST &OURIER TRANSFORM &&4  IS INVARIABLY EXPLOITED TO EXPEDITE    THE PROCESSING 4HE IMAGE DATA PRESENTED IN &IGURE  WERE COLLECTED FOR A STEPPED 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas.  REFLECTOR ANTENNAS  12.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 outputs to form a high-gain low-sidelobe beam and the difference of the two squinted  beams to form a precise, deep null at boresight. 
 (The length of the  line can be made proportional to target speed.) The use of a computer to generate the  graphics and control the CRT display offers flexibility in the choice of such things as range  scales. off center display. blow-up of selected areas, physical map outlines, grid displays, airport  runways. 
 If a determined adversary is willing to pay the resultant price, sufficient ECM can be  brought to bear against any single radar to significantly reduce its effectiveness. This should  not evoke pessimism on the part of the radar designer since it can be said that any military  objective can be accomplished by a determined force if the force is skillful and large enough,  and if cod is of no consequence. Tlle goal of ECCM is to raise the cost of ECM' to the point  where it is prohibitive. 
 Battan, Radar Observation of the Atmosphere , Chicago: University of Chicago Press, 1973. 21. D. 
 That is, the playback speed is increased in proportion to the  number of time-delay intervals T, that are to be tested.  Since the cross-correlation receiver and the matched-filter receiver are equivalent math-  ematically, the choice as to which one to use in a particular radar application is determined by  which is more practical to implement. The matched-filter receiver, or an approximation, has  been generally preferred in the vast majority of applications. 
 DOPPLER 
 As the wavelength is increased, the category of a given facet changes from large to small', eventually the facet is smaller than a wavelength, and its reradiation pattern shape remains almost isotropic from that point. Many fac- ets that would be separate at, say, a 1-cm wavelength are combined at a 1-m wavelength; the result may be a transition from rough- to smooth-surface be- havior. Figure 12.6« shows a number of facets of different sizes contributing to a radar return. 
 Eng. Rept. 3648-1-7, 1961. 
 5 The vertical gradient of the  refractive index d11/dh is normally negative. Ir it is assumed that this gradient is constant with  height and equal to a value of 39 x 10-6 per meter, the value of k isl The use of the j effective  earth's radius to account for the refraction of radio waves predates radar and, because of its  convenience, has been widely used in radio communications, propagation work, and radar.13  It is only an approximation, however, and may not yield correct results if precise radar  measurements are desired, as, for example, in a long-range height finder. The term standard  refi·actio11 is applied when the index of refraction decreases uniformly with altitude in such a  manner that k = j (Ref. 
 18. Donaldson, R. J., Jr.: The Measurement of Cloud Liquid-Water Content by Radar, J. 
 WIDTH CAN BE IMPROVED BY CASCADING SEVERAL SHEETS  AS SHOWN IN &IGURE  4HIS CREATES WHAT IS KNOWN AS A  *AUMANN ABSORBER 4HE BANDWIDTH RISES WITH THE NUMBER  OF LAYERS AND CAN ATTAIN A RESPECTABLE  FOR A FOUR 
 ALARM PROBLEM !DAPTIVE THRESHOLDING AND NONPARAMETRIC DETECTORS ASSUME THAT THE SAMPLES IN THE  RANGE CELLS SURROUNDING THE TEST CELL CALLED  REFERENCE CELLS  ARE INDEPENDENT AND IDENTI 
 This  scheme is vulnerable to variations in the soil electrical and magnetic properties, such  as those resulting from seasonal changes in soil moisture levels. • Injection of a calibration waveform at the antennas, or at the receiver inputs behind  the antenna array, by means of an independent “open loop” signal feeder network.125  This scheme cannot calibrate the antennas and initial feeders; it applies only from  the point where the signal is injected. • Use of a distant radiating source that illuminates the array via skywave or even  a discrete target echo. 
 SIGHT OR  BEAM POSITION 4ARGET REPORTS ARE GENERATED  FOR EACH DWELL ! BAR REFERS TO A LINE OF BEAM POSITIONS AT A CONSTANT ELEVATION )N SEARCH  A MULTI 
 Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 11.2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 11 for future system requirements. For example, microwave power tubes continue to pro - vide significantly higher power output and efficiencies than solid-state power ampli - fiers for high performance millimeter-wave radars.5 Compared with tubes, solid-state  devices offer the following advantages: ● No hot cathodes are required; therefore, there is no warmup delay, no wasted heater  power, and virtually no limit on transistor operating life. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 6.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 A truly coherent radar generates all frequencies, including its inter-pulse periods, from  a single frequency reference. 
 32 MU), which had been given the task of installing the newly developed ASV and AI radars into Hudson and Blenhe im aircraft, respectively [ 4]. No. 32 MU was subsequently involved with developing installations of new ASV radars in differ- ent aircraft throughout WWII. 
 The  resulting blind speeds will be the same as if the radar transmitted the difference frequency  rather than the carrier. For example, if llf = O.lf0, the first blind speed corresponding to the  difference frequency is 10 times that of an MTI radar at the carrier frequency Jo. Thus, it would  seem that the advantages of a VHF or UHF MTI might be obtained with radars operating at  the higher microwave frequencies. 
 CALLED SPACED ANTENNA TECH 
  
 606-612, September, 1971.  59. Baars, J. 
 BAND KLYSTRONS IN THE !7!#3 RADAR 7HEN EACH OF THE TWO NARROW 
 WAVE FREQUENCIES 4HE LARGE MAGNETIC FIELDS NEEDED FOR MILLIMETER 
 WIDTH IS THE BEAMWIDTH OF THE ELEMENT IN THE ARRAY RATHER THAN THE ARRAY BEAMWIDTH 7ITH CIRCULAR POLARIZATION  THE SIGNAL RETURNED FROM A SINGLE 
 There are several sources of  mismatching; the imperfect matching of the analogue receiving channels is one of the  main limitations to the interference cancellation. The effect of this mismatch on the  JCR has been studied in the literature; see Farina57 and references therein. For contemporary presence of amplitude and phase mismatches, the JCR has an  expression that is derived in Appendix 2.57 A numerical application of this equation is  shown in Figure 24.3; the parameter values of the study case are quoted in Farina.57  Figure 24.3 shows the JCR contour curves versus the normalized amplitude an and the  phase b (degrees) mismatches of the analogue receiving channels (see Farina57 for the  precise definition of these parameters). 
 II.Meyer,D.PooandH.A.Mayer:"Radar TargetDetection," Academic Press,NewYork,1973. 12.Hollis.R.:FalseAlarmTimeinPulseRadar,Proc.IRE,vol.42,p.1189,July,1954. 13.Trunk,G.V.:Detection ResultsforScanning RadarsEmploying Feedback Integration, IEEETrailS.. 
 B. J. Slocumb and P. 
 STATE TRANSMITTERS 4HE MOST IMPORTANT OF THESE  IS THAT AFFORDABLE MAGNETRON 
 S. Reed: An Analysis of Signal Detection and Location by Digital Means, I RE  .j Trans., vol. IT-2, pp. 
 5.2). The angle between  the axis of rotation (which is usually, but not always, the axis of the antenna reflector) and the  axis of the a111c1111a hca111 is called the squint angle. Consider a target at position A. 
 This error signal isamplified byvacuum-tube circuits and used todrive themotor that turns theload. Proper phasing isdeter- mined byreference tothe line voltage, usually byusing the latter to provide field current forthemotor. Asinthedouble-synchro direct-drive system, ‘[gearing up” isoften used. 
 63. 64 PROPERTIES OFRADAR TARGETS [SEC. 3.3 ofback scattering from asphere ofradius asmall compared totheradar wavelength. 
 ALLY SWITCHED INTO USE AND SET BY BEARING  BEAM RANGE  AND LENGTH 0)S ARE TYPICALLY USED TO ENSURE THAT A SHIP IS MAINTAINING A SAFE GROUND TRACK  WITH REFERENCE TO A GROUND 
 It had a peak transmitter power in X-band of about 50 kW, with pulse lengths of 0.5μs at a PRF of 1200 c/s, 1 μs at 1200 or 600 c/s and 2.25 μs at 350 c/s. Range scales of 10, 20, 40, 80 and 160 miles were provided, with automatic selection of pulse length and PRF. The radar included strobe unit type 67, for accurate ranging on targets, and Lucero TR 3505 (see chapter 6andﬁgure 6.2). 
 36.  pp. 1289-1296, October, 1948. 
 The amplification takes place at the doppler frequency. At 10,525 MHz, one of the frequencies currently approved by the Federal Communications Commission (FCC), 50 m/h corresponds to 1570 Hz, which is in a convenient range. A squelch circuit is used to prevent random or noisy signals from reaching the counter. 
 This condition is not as commonassuper-refraction.Sub-refractioncanoccurinpolarregionswhereArcticwindsblowoverwaterwhereawarmcurrentisprevalent.Ifalayerofcold, moist air overrides a shallow layer of warm, dry air, a condition knownas SUB-REFRACTION may occur (see ﬁgure 1.8). The effect of sub-refraction is to bend the radar rays upward and thus decrease the maximumranges at which targets may be detected. Sub-refraction also affects minimum ranges and may result in failure to detect low lying targets at short range. 
 TANEOUS DYNAMIC RANGE AND THE TOTAL DYNAMIC RANGE THAT IS ACHIEVED AS A RESULT OF PROGRAMMED GAIN VARIATION 2ECEIVER )NPUT .OISE ,EVEL  "ECAUSE MANY RADAR SYSTEMS INCLUDE LOW 
 POLE  FILTER OF THE FORM  YI YI XI         
 1977, IEE (London) C'onf. Pitbl. no. 
 Another factorthatcomplicates operation ishysteresis whichcauses thevalueofpermeability todifferforincreasing anddecreasing current.Toeliminate hyster­ esiserrorsacurrentpulsemustbeappliedtothephaseshiftersolenoid todrivetheferrite10 Ferrite tOrOid (a) Dielectric Dielectric matching spacers transformer Latching Ferrite conductor toroid (Drivewire) (b) Figure8.10(a)Singlebitofalatching ferritephase-shifter mounted inwaveguide; (b)skelchoffive-bit latching ferritephase-shifter. (FromWhicker andJones, 156courtesy 1EEE.). 1.HF ELdECTRONICALLY STEERED PHASED ARRAY ANTENNA IN RADAR 293  saturatiorl before a new value of phase shift can be applied. 
 8.6), since the electromagnetic energy must  travel in both directions. Their use is also not practical in short-range radar or with high-duty  cyde waveforms like those used in some pulse-doppler radars, since the switching between the  two states is too slow.  The value of remanent magnetization is affected by temperature. 
 2.11. Evidently the detection ofsuch atarget will depend critically onitsrange and altitude. lfanairplane flies intoward the radar atconstant altitude hZwemust expect the signal tovanish and reappear repeatedly, asthelobe structure istraversed. 
 England). 110. 40. 
 ch17.indd   28 12/17/07   6:49:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 
 R.: "Introduction to Monopulse," McGraw-Hill Book Company, New York, 1959.  18. Barton. 
 Layover.  SAR processing sorts target returns into bins (pixels) depending on the  range R and velocity v of the target relative to the platform. If two or more targets have  the same R and v, then they will be placed at the same location in the SAR image. 
   '2/5.$ %#(/  £È°xÎ 4HE RESULTS WERE DESCRIBED IN TERMS OF  R &  WHICH WAS CALLED  CLUTTER STRENGTH  & IS A PROPAGATION FACTOR THAT ACCOUNTS FOR MULTIPATH  ATTENUATION  ETC  BUT COULD NOT  BE MEASURED SEPARATELY 7HEREAS  ANGLE OF INCIDENCE IS USED TO DESCRIBE RESULTS IN STUDIES WHERE POINTING  IS NEARER VERTICAL  DEPRESSION OR GRAZING ANGLE IS A MORE APPROPRIATE DESCRIPTION WHEN DEALING WITH ANGLES WHERE INCIDENCE IS CLOSER TO HORIZONTAL 'RAZING ANGLE IS THE COM 
 BASED RADAR DETECTION OF LOW 
 FORCE REMEDY IS TO PHYSICALLY BLOCK THE TRANSMIT SIGNAL FROM THE RECEIVER WITH A SHROUD OR STRUCTURE  OR IF COVERAGE ALLOWS  OVER 
 Other Modeling Approaches.  The models described above are formulated in the  context of the radar equation (Eq. 20.2). 
 It is  not represented explicitly in some ionospheric models where its effects are accounted  for with an empirically derived path-loss calculation. E Region.  This ionization region extends between about 90 and 130 km in alti - tude with a maximum near 110 km when sunlit. 
 POWER BEAMWIDTH  RADIANS  S   COMPRESSED PULSE WIDTH  @   GRAZING ANGLE AT CLUTTER PATCH 4HE REMAINING TERMS ARE AS DEFINED FOLLOWING %Q  )F THE MAIN BEAM IS POINTED BELOW THE HORIZON  THE MAIN 
 Figure 10.48 shows ahydrogen-thyratron pulser designed tosupply 225 kwtothe magnetron, atpulse durations of0.25, 0.5, 2.6, and 5.2 psec. The weight ofcomponents isabout 40lb. Figure 10.49 shows afixed-gap pulser designed tosupply 2Mw tothe magnetron atapulse duration of2~sec. 
 LAW WIND 
 Analyze the principle of FM -CW radar and apply it in FM -CW Altimeter.   3. Differentiate between a MTI Radar and a Pulse D oppler Radar based on their working  principle. 
 QUANTIZATION LOBES 3ECTION   3PACE PROBLEMS MAY BE ENCOUNTERED IN ASSEMBLING AN ACTUAL SYSTEM  ESPECIALLY AT HIGHER FREQUENCIES  BECAUSE ALL CONTROL CIRCUITS HAVE TO BE BROUGHT OUT AT THE SIDE OF THE APERTURE OF THE LENS ARRAY -ULTIPLE BEAMS MAY BE GENERATED BY ADDING FURTHER PRIMARY FEEDS !LL THE BEAMS  WILL BE SCANNED SIMULTANEOUSLY BY EQUAL AMOUNTS IN SIN P 4HE REFLECTARRAY SHOWN IN &IGURE B HAS GENERAL CHARACTERISTICS SIMILAR TO THOSE  OF THE LENS (OWEVER  THE SAME RADIATING ELEMENT COLLECTS AND RADIATES AFTER REFLECTION  !MPLE SPACE FOR PHASE 
 STATE TRANSMITTERS AND  VACUUM TUBE TRANSMITTERS HAVE SIGNIFICANT DIFFERENCES  YET THEY ARE BOTH EMPLOYED  .   4(% 2!$!2 42!.3-)44%2   £ä°ÓÇ IN RADAR 3OME OF THESE DIFFERENCES ARE MENTIONED IN 3ECTION  OF #HAPTER  h3OLID 
 BIT BINARY SEQUENCES )T CAN BE SEEN THAT THE "ARKER CODE PROVIDES THE LOWEST TIME SIDELOBE LEVELS OF ALL POSSIBLE CODES   !LLOMORPHIC &ORMS  ! BINARY CODE MAY BE REPRESENTED IN ANY ONE OF FOUR ALLO 
 25.38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 faster and more powerful ADCs, DSP devices, and general-purpose processors, more  and more of the radar system front end will move from analog to digital designs. For  example, Figure 25.2 shows a typical digital receiver for a radar front end, which requires  two stages of analog downconversion to bring the RF signal down to an IF that can be  sampled by an ADC. This is required because of the characteristics of the ADC, which  typically has poorer signal-to-noise ratio (SNR) and spur-free dynamic range (SFDR)  when the input analog signal is too high, as would be the case if it were presented with  the RF or high-IF signal directly. 
 &OURIER TRANS 
 TION WITH SCANNING IS DRAMATICALLY GREATER THAN COS P 4HE SMALL ARRAY CAN ALSO BE USED TO MEASURE COUPLING COEFFICIENTS AS DEMONSTRATED  BY &IGURE  4HESE COUPLING COEFFICIENTS CAN BE USED TO CALCULATE THE IMPEDANCE VARIATION AS THE ARRAY IS SCANNED 'ROVE  -ARTIN  AND 0EPE  HAVE NOTED THAT FOR THE ELE 
 TION WIDTH IS   $2C "     4 IME 
 IEEE, vol. 57, pp. 468-480, April, 1969. 
 TO 
 It is  important in a paraboloid that the phase of the radiation emitted by the feed be independent of  the angle. The radiation pattern produced by the feed is called the primary pattern; the  radiation pattern of the aperture when illuminated by the feed is called the second,iry pattern.  A simple half-wave dipole or a dipole with a parasitic reAector can be used as the feed for  a paraboloid. 
 FLYING AIRCRAFT AND HELICOPTERS AS A GAP 
 19.5 is representative of the earliest systems developed in the late 1940s and early 1950s. The simplest implementation of a CW missile seeker, it consists of a rear receiver, a front receiver, a signal processor (speedgate), and a tracking loop to control the gimballed front antenna. The missile also contains an autopilot to guide it and stabilize the airframe, a fuze to detonate the warhead at the optimum time, and a source of electrical and (in most missiles) hydraulic power. 
 70. IEEE Standard Letter Designations for Radar-Frequency Bands,/£££ Std 521-1976, Nov.30.1976.  71. 
 All decision aids are displayed as functions of range,  azimuth angle, and/or height. Detection probability, ESM vulnerability, and communi - cations assessments are based on EM system parameters stored in a user-defined and  changeable database. In addition to normal radar parameters, a user may completely  define the antenna radiation pattern to account for sidelobe considerations. 
 ING OF THE ELEMENTS WITH A NONUNIFORM AMPLITUDE  GA  7HEN SCANNING TO AN ANGLE IS  P  THE GAIN OF A PLANAR ARRAY IS REDUCED TO THAT OF THE PROJECTED APERTURE   'P  y O .G   COS P  3IMILARLY  THE SCANNED BEAMWIDTH IS INCREASED FROM THE BROADSIDE BEAMWIDTH  EXCEPT IN THE VICINITY OF ENDFIRE  P   n    PP P"" COSSCANNED BROADSIDE y   4HE TOTAL NUMBER OF BEAMS  - WITH BROADSIDE BEAMWIDTH AND SQUARE STACKING   THAT FIT INTO A SPHERE IS APPROXIMATELY EQUAL TO THE GAIN AND WITH  G  y  IS THUS SIMPLY  RELATED TO . BY   - y O .  !N ARRAY WHERE THE ELEMENTS ARE FED IN PARALLEL SEE 3ECTION   AND SCANNED BY  PHASE SHIFT  MODULO  O  HAS LIMITED BANDWIDTH FOR WIDEBAND OPERATION  CONSTANT PATH  LENGTHS RATHER THAN CONSTANT PHASES ARE REQUIRED 4HE LIMIT IS GIVEN BY   "ANDWIDTH   y BEAMWIDTH n   4HIS IS EQUIVALENT TO LIMITATIONS GIVEN BY   0ULSE LENGTH    r APERTURE SIZE  7ITH THESE CRITERIA  THE SCANNED RADIATION PATTERN AT  n IS STEERED BY  o ONE 
 (Thisandotherautomatic detectors aredescribed in Sec.10.7andinRef.70.)Bylocating thecenterofthenpllls_es,anestimate ofthetarget's angulardirection canbeobtained. Thisiscalledbeantsp/ittiJW. Ifthereisbutonetargetpresentwithintheradar'scoverage, thendetections ontwoscans areallthatisneededtoestablish atargettrackandtoestimate itsvelocity. 
 200INTRODUCTION TORADAR SYSTEMS Figure6.8Schematic vieworacoaxialmagnetron showing thetuningpistonmechanically actuated byavacuum bellows...RF output waveguide• \Outputvacuum window Vacuumbellows Innercircuitmode allenuator Cathode TuningpistonMagnetic fieldlines Coupling slol Vaneresonator Cavitymode attenuator TEollmode Electricfield lines TEallstabilizing ~~kr:F="'i'l cavily Therapidtuningoveranarrowband forpurposes ofproviding frequency agilityis sometimes calleddithertuning.39Inaddition tobeingcapableofrapidtuningoveranarrow­ band,thesetubesalsocanbetunedtoafrequency overabroadband inthenormalmanner usingageareddrive.Thetuningmechanism maybecontrolled byaservomotorsoastoselect electrically anyspecificfrequency withintheoperating bandeithermanual.ly oronanautoma­ tic,programmed basis.Withservo-motor control,thetubecanhetunedfromonefrequency 10 another inunder0.1second. Dither-tuning ofacoaxialmagnetron mayalsobeobtained byamechanical tuning elementcalledaringtuner.5,6Thisconsistsofanarrowringinstalled inanannulargroovecut intotheouterwallofthecavity.Theringprojectsslightlyintothecavity.Theringissplit,with thesplitdiametrically opposite theoutputcavity.Theringisalsocuttoaccommodate the outputcoupling slot.Neartheoutput,onbothsidesoftheoutputcoupling, theringisfirmly attached tothecavitywall,butisunattached otherwise. Bydeforming theringinwardfrom mechanical motionappliedtothefree-hanging endsofthering,thetuningofthecavi:yis changed. 
 Wimberley, F. T .. and J. 
 DOPPLER COUPLING 4HESE RANGE DISPLACEMENTS MUST MATCH IN  THE TWO RECEIVERS TO WITHIN A SMALL FRACTION OF THE COMPRESSED PULSE WIDTH OTHERWISE  THE SENSITIVITY BENEFITS OF DIPLEX OPERATION ARE NOT FULLY ACHIEVED AND RANGE ACCURACY MAY BE DEGRADED )MPLEMENTATION  $IPLEX OPERATION CAN BE IMPLEMENTED WITH A VARIETY OF  APPROACHES #OMPLETE REPLICATION OF THE RECEIVER CHANNELS IS TYPICALLY THE MOST EXPEN 
 15.20 the improvement factor of an MTI using the optimum weights is compared with the binomial coefficient MTI for different values of the relative clutter spectral spread and shown as a function of the number of pulses in the CPI. These results again assume a gaussian-shaped clutter spectrum. For typicalAVERAGESCR IMPROVEMENTOPTIMUM FILTERWEIGHTSFIXEDATASCR IMPROVEMENT ISCR (dB) . 
 _., or else complete independence from pulse to pulse (fast fluctuation). These represent two  extreme cases. In some instances, there might be partial correlation of the pulses within a scan  (moderate nuctuation ). 
       $AY (n   
 TEC retrieval from spaceborne SAR data and its applications. J. Geophys. 
 For purposes of illustration it is shown in Fig. 4.36 as a  uniform spectrum.  The altitude return may be eliminated by turning the receiver off (gating) at that range  corresponding to the altitude of the aircraft. 
  -ULTIFUNCTIONAL !%3! 2ADAR  #OURTESY 2AYTHEON  #OMPANY    &)'52%  -&!2 INTERLEAVES ! 
 This page has been reformatted by Knovel to provide easier navigation. Contents     xv   Small Arrays  ......................................................  7.35  7.5 Low-Sidelobe Phas ed Arrays  ................................. 
 #7  A FREQUENCY 
 Britt: Phantom Radar Targets at Millimeter Radio  Wavelengtlis. IRE Trclrts.. vol. 
 STATE DEVICES AND IS NOT DISCUSSED  FURTHER IN THIS CHAPTER  4HE KLYSTRON IS AN EXAMPLE OF  A LINEAR 
 M. (MITRE Corporation): private communication, April 1988. 104. 
 (a)kω=−0.005 rad/s ( b)kω=−0.007 rad/s. Figure 7. Coherent length with different spectral index. 
 L., and L. J. Greenstein: A Generalized Clutter Computation Proce- dure for Airborne Pulse Doppler Radars, IEEE Trans., vol. 
 While the formula for the distance to the radar horizon is based upon a wavelength of 3cm, this formula may be used in the computation of the distance to the radar horizon for otherwavelengths used with navigational radar. The value so determined shouldbe considered only as an approximate value because the mariner generallyhas no means of knowing what actual refraction conditions exist. Sub-refraction The distance to the radar horizon is reduced. 
 DAMENTAL 4HE PERIODIC NATURE OF DIGITAL PHASE SHIFTING AT EACH RADIATING ELEMENT CAN CREATE MULTIPLE DISTINCT LOCATIONS IN SPACE WHERE PARASITIC BEAMS GRATING LOBES  CAN OCCUR )N ARRAY DESIGN  THIS IS AVOIDED IF THE RADIATING ELEMENT SPACING  D  IS LESS THAN  THAT DESCRIBED BY   D   K    SINP 
 This isaccomplished bymoving arange sweep laterally across thetube face in synchronism with theantenna motion sothat the origin isstretched out into aline. Inrange and azimuth these rectangular displays areoftwo different sorts: 1.Displays inwhich noattempt ismade tominimize thedeformation, either because itisunimportant inthe particular circumstances, orbecause certain advantages canbegained byneglecting it. Any desired range interval and azimuthal sector may becovered, although inpractice more than 180° israrely used. 
 pp. 80-94, April, 1961.  17. 
 REPEAT MIS 
 strong, overriding receiver noise, but target angle scintillation errors proportional to the angular span of the target are large. A wider servo bandwidth is needed at close range to keep tracking lag within reasonable values, but it must not be wider than necessary or target scintillation errors become excessive. The low-pass closed-loop characteristic of a servosystem is unity at zero fre- quency, typically remaining near this value up to a frequency near the low-pass cutoff, where it may peak up to higher gain, as shown in Fig. 
 R.K..N.F.Moody. P.M.Thompson, R.J.Bibby,C.A.Franklin, J.H.Ganton, and1. Mitchell: ALightweight andSelf-contained Airborne Navigational System, Proc.IRE,vol.47, pp.778-807. 
 Imaging results obtained by adopting traditional approach and proposed approach respectively under 5 dB Noise. ( a) Traditional imaging processing; ( b) imaging processing of proposed approach (mixed Euclidean norm); interferometric phase images (top layer); complex images of channels 1 and 2 (second and third layers); ﬁnal 3-D imaging results (last layer). Figure 7describes MSE estimated by heights of four compressed sensing approaches under different SNRs. 
 69. Kroszczynski, J.: Efficiency of Attenuation of moving Clutter, TIie Radio a11d E/l!ctro11ic £11gr., vol. 34. 
 FIELD ANTENNA RANGES   WHERE  COMPUTER 
 308 309  suharrays in, 309 3 IO  switched-line phase shifter for, 288  thinned, 309, 319, 331-332  triangular element spacing in, 333-334  twin-slab phase shifters for, 294  unequally spaced, 331-332  ARSR-3, 538-541  Artificial dielectric lenses, 249--252  ASR, 536-537  Asymmetric monopulse, 175  Atmospheric attenuation, 459-461  Atmospheric noise, 461-463  Attenuation in waveguides, 57  Automatic detection, 183-184, 388-392  Automatic detection and track (ADT), 153,  183-186, 392  Automatic gain control, 157-158  and amplitude fluctuations, 168  and angle fluctuations, 169  in monopulse, 164  Automobile, radar cross section of, 44  Az-el mount, 271  B sandwich radome, 267  Balanced duplexers, 360-361  Balanced mixers, 348-349  RAM, 510l  Bandwidth:  CW radar, 75-76  effective, 404-405  klystron, 203  noise, 18  tracking, 178  Barker code, 428-429, 432  Bayes' rule, 377-378  Bayliss pattern, for monopulse, 258  Beam shape loss, 58-59  Beam-sharpening mode, SAR, 527  Beam splitting, 184, 390, 392, 400  Beam steering. array, 282-285  Beam-steering computer, 323  Bed of spikes ambiguity diagram, 418-419  Binary moving-window detector, 388-390 Binomial coefficients, in MTI, 110  Bipolar video, 103-104  Birds, 508-510  Bistatic radar, 553-560  Black-hole effect, in MTI, 137  Blass beam-forming array, 311-312  Blind phases, MTI, 119  Blind speeds, MT[, 108  Blip-scan ratio, 63 INDEX 573  Blocking, of antenna aperture, 223-224, 239  Bootlace antenna, 316  Boxcar generator, 117, 156  Bragg scatter, 480, 534  Branch-type duplexer, 360  Brewster's angle, 444  Bright band, 502  Bright displays, 357-358  Brightness temperature, 461-462  Burnout, diode, 350  Burnthrough, 549  Butler beam-forming array, 311-314  C sandwich radome, 267  Cancellation ratio, MTI, 130  Canonical MTI comb filter, 112  Capillary waves, 480  Cassegrain antenna, 240-242  in Hawk system, 73  Cathode-driven CF A, 212  Cathode pulsing, of CF A, 210  Cathode ray tube display, 353-359  Cell-averaging CFAR, 392-393  CFAR, 392-395  in ECCM, 550  log-FTC, 506  and pulse compression, 433  Chaff, 552-553  Channel tuning, klystron, 204  Charge transfer device (CTD}, for MTI, 126  Chi-square probability density function, 49-51  Chirp pulse compression, 422--427  Circular polarization, and rain, 504-506  Circulator, in duplexer, 365  Clear-air turbulence, 510-511  Clouds, scattering from, 502-503  Clutter, 470-512  angel, 508-512  land, 489-498  at millimeter wavelengths, 563-564  sea, 474-489  weather, 498-508  Clutter attenuation, MTI, l lJ, 130  Clutter doppler spread, AMTI, 142-145  Clutter fluctuations, MTI, 131-134 . 574 INDEX  Clutter-Jock MTI, 142  Clutter map, 184  in MTD, 127  Coaxial magnetron. 
 27. N. W. 
 Frush, J. Testud, and F. Baudin, “The ELDORA/ ASTRAIA airborne doppler weather radar: goals, design and first field test,” Proc. 
 SOURCE MECHANISMS AFTER % & +NOTT Ú !MERICAN  )NSTITUTE OF !ERONAUTICS AND !STRONAUTICS    . 
 RELATED CROSS SECTION INFERRED FROM THE RECEIVED SIGNAL STRENGTH IN  ANY GIVEN MEASUREMENT WILL DEPEND UPON THE PATH LENGTH -OREOVER  THE ROLE OF SEA  SPRAY IN BOTH SCATTERING AND ABSORPTION WILL CERTAINLY BE MORE IMPORTANT THAN AT THE LOWER MICROWAVE FREQUENCIES )T IS DIFFICULT TO FIND CLUTTER DATA AT FREQUENCIES ABOVE + A BAND  ALTHOUGH  ( 
 Potentiometers. -Potentiometers are principally used toprovide voltages whose only frequency components arethose resulting from the scanning. Because even thebest potentiometers have acertain amount ofbrush ‘(jitter” which can beremoved only byfiltering, they arenot very satisfactory forresolving range sweeps. 
 350  Diode phase shifters, 288-291  Diodes, microwave, 217  Directive gain, antenna. 224  Dispersive delay lini.:s, 424 426 .)  Displaced Phase Center Antenna (DPCA).  143 144  Displays, 353 359  dd1nitions of, 354 355  Dither tuning, of magnetron, 200  Dolph-Chcbyshev array, 257  Dome antenna, 329-330  D,oppler filter bank, MTD. 
 The binary quantization of line lengths makes it convenient to apply digital tcchniqu~s  for actuating the shifter.  Figure 8.6 shows the schematic of a four-bit digital phase shifter consisting of four  cascaded modules. Each module contains a switch that inserts either" zero" phase changi: or a  phase change of 360/2n degrees, where n = I, 2, 3, 4. 
 5,  McGraw-Hill Book Company. New York, 1948.  25. 
 . Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 112     € r=0⇒µ0µr ε0εr=µ0 ε0=120πΩ orεr=µr (11.26)   Coatings of this type have been used with airplanes for a few years.  Ferrite (thin layer absor b- ing) is primarily used in the coating material. 
 AES-10. pp. 811-820, November, 1974. 
 Much of the discussion regarding t he statistics of  sea clutter applies as well to land clutter, except that the physical mechanisms may be difTerent.  The statistical variation of crO from homogeneous terrain such as deserts and some types of  farmland can sometimes be described by the gaussian probability density function (pdf), so  that the envelope of the radar receiver output is given by the Rayleigh pdf (Eq. 13.1O).~~Some  urban areas, rural areas with buildings and silos, and mountainous terrain approximate the  log-normal pdf (Eq. 
 14.5 thea-cvoltage, which inaradar setshows upasspoking and blurring of the indicator scope (see Fig. 14.11). The frequency ofthe modulation isnormally 30or40cps. 
 MOVING WAVE STRUCTURES   4HE HALF 
 W.: Technique for Realizing Low Time Sidelobe Levels in Small Compression Ratio Chirp Waveforms, Proc. IEEE Ultrasonics Symp., pp. 478-481, 1973. 
 , .- ttuctuations -- when --  sequential rather than simultaneous angle measurements are made. Changes in echo ampli- .  tilde cause errors since the sequential measurements are necessarily made at different instants  .J544INTRODUCTION TORADAR SYSTEMS fromafundamental pointofviewsinceitusessimultaneous pencil-beam radiation patterns fromasingleaperture tocovertheelevation anglesofinterest. 
 Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 17 .8  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 target with a range resolution of c/2B. Let us also assume that the SAR is moving in a  straight line at a constant altitude H and constant speed V for a time T along a direction  normal to the LOS. 
 C. H. Gager, “The impact of waveform bandwidth upon tactical radar design,” IEE Int. 
 F. T. Ulaby, T. 
 37.Sollenberger, T.E.:Multipath PhaseErrorsinCW-FM Tracking Systems. IRETrans.,vol.AP-3, rr.185-192. October. 
 W. Burlage, “Improved MTI performance for phased array in severe clutter  environments,” in IEEE Conf. Publ. 
 Any use is subject to the Terms of Use as given at the website. Radar Cross Section.  RADAR CROSS SECTION  14.436x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 that spoil the corner-reflector effect. Surface tilting also moves the radar angle of  incidence well into the far sidelobes of most surfaces on the vessel. 
 IEEE T rans. Antennas Propag. 1998 ,46, 730–735. 
 S. Brown, and G. S. 
 In general, it is not possible to make a reliable estimate of propagation velocity or rela - tive permittivity in a medium from a single measurement without trial holing (inserting a  probe into a predrilled hole) or other supplementary information. Even in the case where  a measurement is carried out at one location, it is often found that significant variations in  velocity will occur within comparatively short distances from the original location. This  can lead to significant errors in the estimation of depths of reflectors. 
 More than 83.81% of persistent scattered (PS) points obtain a standard deviation of less than −6 mm/yr, and the difference between SBAS-InSAR method and leveling data is less than 5 mm/yr. Thus, we conclude that SBAS-InSAR method with Radarsat-2 data is reliable for longtime monitoring of land subsidence covering a large area in Wuhan city. In addition, land subsidence is caused by a combination of natural conditions and human activities. 
 A three-pulse MTI filter using binomial weights has a filter mismatch loss of 0.51 dB.  The mismatch loss for the binomial-weighted four-pulse canceler is 0.97 dB. Clutter Visibility Factor ( Voc) The IEEE definition is clutter detectability factor:  The predetection signal-to-clutter ratio that provides stated   probability of detection for a given false alarm probability in an automatic detection circuit. 
 789–797, November  1984. 36. G.V . 
               .   %,%#42/.)# #/5.4%2 
 DOPPLER DETECTION SPACE &INALLY  THE TRACK CAN BE UPDATED WITH THE AMBIGUOUS RANGE 
 The phase shift associated with the return  signal is (4TCfRo/c)/(l - v/c), where R, is the range at time r = 0.  Applications of CW radar.24s25 The chief use of the simple, unmodulated CW radar is for the  measurement of the relative velocity of a moving target, as in the police speed monitor or in  the previously mentioned rate-of-climb meter for vertical-take-off aircraft. In support of auto-  mobile traffic, CW radar has been suggested for the control of traffic lights, regulation of toll  booths, vehicle counting, as a replacement for the " fifth-wheel" speedometer in vehicle testlng,  as a sensor in antilock braking systems, and for collision avoidance. 
 Any use is subject to the Terms of Use as given at the website. Bistatic Radar.  BISTATIC RADAR  23.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 with the monostatic caveats cited above. Thus, this oval (or ovals) provides a   convenient—but at times over-simplified—view of bistatic range coverage and  must be used with care. 
 However, it was noted that the toneheard by a receiver would increase when the radar was diving towards it and this might serve to offset the decrease in PRF due to the attenuator, preventing a receiver operator being alerted to any changes. It was found that power could be reduced to about 1/3 of its maximum value (from 35 W mean power to about 13 W mean power, as measured on test set 28),while the PRF changed from 315 c/s at maximum power to 255 c/s at minimum power. The report recommended that Vixen be installed in all ASV Mk. 
 31 (The term" Ideal" does not  necessarily imply that this criterion is the ideal criterion.) The criterion of the Ideal Observer  maximizes the total probability of a correct decision (or minimizes the total probability of an  error). Since t~e two ways in which an error might be made are (l) false aJarm and (2) missed  detection, the probability of ari error is.  p(E) = p(N)pra + p(SN)pm ( I0.32)  where p(N) and p(SN) a priori probabilities of obtaining noise and signal-plus-noise, re­ spectively [p(N) + p(SN) = l]  Pra = conditional probability of a false alarm, given that noise is present  Pm = conditional probability of a miss, given that signal is present (a, fJ  are often used in mathematical references for P,a and Pm)  The a priori probability is the probability of obtaining either noise alone or signal-plus-noise  before the detection decision is made. 
 The switch shown in Fig. 6.14 is a hydrogen thyratron, but it can also be a mercury  ignitron, spark gap, silicon-controlled rectifier (SCR), or a saturable reactor. A gas tube such  Energy  source Charging  impedance  f------ 1  l  I Switch  I.__ --- Charging path Energy  storage  element  ------) (-----i I  t r t  I I I '-____ _) __ _)  Discharge path load  Fi1ure 6.13 Basic elements of one type  of radar pulse modulator. 
 204 INTRODUCTION TO RADAR SYSTEMS  problem, but the tuner increases the cavity capacitance and thus decreases the cavity im-  pedance so that there is reduced bandwidth at the low-frequency end of the tuning range  Tuning ranges of 10 to 15 percent can be obtained without a compromise in impedance by  using a sliding-contact movable cavity wall, but at the expense of increased mechanical  complexity.  To simplify the tuning of a klystron it is desirable to have a "gang tuner " by which all the  cavities are controlled by a single knob when changing frequency. Gang tuning is complicated,  however, since the resonant cavities do not generally have the same tuning rates. 
 A discrete target return in the main beam is shown at fr = /o + (2V/A) cos i|;0 + (2V7JK) cos i|ir, where the target velocity is VT, with an angle i|/r between the target velocity vector and the radar target line of sight. FIG. 17.2 Unfolded spectrum (with no clutter tracking). 
 Similarly, the reflectivity  is a function of the polarization of the transmitted wave. Thus, if the scattering func - tion itself is to be fully characterized, two orthogonal polarizations must be transmit - ted as well. Increasingly, polarimetric diversity is being implemented in space-based  SARs.41,57 Implementation of a fully polarimetric radar always implies greater data  channel capacity, more transmitted power, and less range swath coverage. 
 A limiter may be necessary to ensure  this. An N-bit converter divides the output of the phase detector into 2N - 1 discrete intervals.  According to Shrader,' the quantization noise introduced by the discrete nature of the A/D  converter causes, on the average, a limit to the improvement factor which is  This is approximately equal t6 6 dB per bit since each bit represents a factor of two in  amplitude resolution.22 When a fixed signal of maximum level is present, a possible error of  one quantization interval is possible. 
 Phased Arrays Symp ., 1985, pp. 187–206. 62. 
 LOCKED  FREQUENCY 
 FIGURE   16. 43 Example of frequency response of s 0 for different kinds of sea ice ( from Y. S. 
 257 262. I EE Conference  Puh. no. 
 RESPONSE &)2  FILTER OR AN INFINITE 
 Meteorol ., vol. 6, pp. 243–248, 1949. 
 Consider anabsorbing atmosphere atanambient temperature 1;,surrounded byan imaginary blackbody atthesametemperature. ThelossListhefactorbywhichenergyis. 462 INTRODUCTION TO RADAR SYSTEMS  Frequency, MHz  Figure 12.11 Maximum and minimum brightness temperatures of the sky as seen by an ideal single-  polarization antenna on earth. 
 ORBITING FORMATION 4HE BASIC 3!2 INTERFEROMETRIC ENVIRONMENT IS ONE IN WHICH THERE IS A PAIR OF  MUTUALLY COHERENT IMAGES THAT HAVE EMBEDDED PHASES THAT DEPEND ON THE DETAILS OF VIEWING GEOMETRY AND SCENE STRUCTURE 4HE COHERENTLY COMBINED IMAGES ARE KNOWN AS AN INTERFEROGRAM  WHICH TYPICALLY CONTAINS FRINGES THAT EXPRESS THE INTERACTIONS BETWEEN THE PHASE STRUCTURE OF THE TWO DATA SETS 3IGNAL PROCESSING IS DESIGNED TO ESTIMATE THESE PHASE DIFFERENCES  AND TO DEDUCE GEOPHYSICAL PARAMETERS OF INTEREST FROM THE RESULTING MEASUREMENT  4HE INTERFEROMETRIC SIGNAL MODEL IS SIMPLE IN CONCEPT &OR ANY NEIGHBORHOOD IN THE  SCENE  THE INPUT SIGNAL PAIR MAY BE DESCRIBED BY   ST A J  EXP; = 
 Although the disorganized-looking ocean surface is represented as the Fourier sum  of an infinite number of sinusoidal wave trains, each with its characteristic wave - number and direction, the principal “first-order” contributions to the scattered field  arise from only two ocean wave trains,82 namely those whose wave vectors satisfy  the relation    k±= ± − ( )k kscat inc (20.7) For the simple case of backscatter at grazing incidence, the geometry for mono - static surface wave radar,   k kscat inc = − , so these resonant ocean waves have a wave - length equal to one-half of the radar wavelength, with one solution corresponding  to a wave directly approaching the radar and the other receding from it. The corre - sponding doppler shifts are those associated with the phase velocity of the resonant  waves, that is  fg g f cf MHzd= ± = ± ≈ ±π πl0102. ( ) (20.8) where the doppler shift fd is in Hz;  g is the gravitational acceleration (9.8 ms-2), f is the  radar frequency, and c the velocity of light. 
 But with the introduction of PPI technique the beacons  show up as ‘winking’ spots or arcs of light in their  positions relative to the interrogator, on the scale of the  map-like PPI picture.  Comparison can be made between these transponder  beacons, which blip only when blipped at, and the  reflecting signs on our main roads, which glisten and  warn motorists only when the car headlamps illuminate  their midget reflectors.  Beaconry in radar offers a wide scope, for we can have  fixed marker beacons or we can arrange to drop beacons  on parachute harness or fit them to buoys at sea. 
 The MTI  response has a peak value of 4 6 4 26 / .≈ dB, resulting in an average noise gain of  unity, and the straight line approximation follows the low frequency asymptote up to  the 0 dB level, which occurs at f T = 0.249, and stays constant at the 0 dB level at all  higher frequencies. The justification for the 0 dB approximation at the higher frequen - cies is that the oscillator spectral density is more nearly constant and the average over  one period of the MTI response is unity. For other binomial coefficient MTI cancelers,  the break frequencies for the start of the response falloff are f T = 0.225 for one delay,  0.249 for two delays, 0.262 for three delays, and 0.271 for four delays. 
 A low-power signal is applied to the input of the first cavity and  appears at the interaction gap . Those electrons in the beam that arrive at the first  interaction gap when the input signal voltage is at a maximum (the positive peak  of the sine wave) are speeded up compared to those electrons that arrive at the gap  when the input signal voltage is a minimum (the negative trough of the sine wave).  FIGURE 10.1  Representation of the principal parts of a three-cavity klystron amplifierRF ca vities Electron beam Cathode Heater Modulating anode Electron gunRF inDrift space RF out RF section CollectorAnodeInteraction gaps Collector ch10.indd   5 12/17/07   2:19:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
   PP n    0 7 'AISER AND # 3 2UF  h&OREWORD TO THE SPECIAL ISSUE ON THE 7IND3AT 3PACEBORNE  0OLARIMETRIC 2ADIOMETERCALIBRATIONVALIDATION AND WIND VECTOR RETRIEVAL v  )%%% 4RANSACTIONS  ON 'EOSCIENCE AND 2EMOTE 3ENSING  VOL   PP n    ) ( 7OODHOUSE AND $ ( (OEKMAN  h$ETERMINING LAND 
 This is a deflection-modulated display. It is more suited for tracking-radar applica-  tion than for surveillance radar.  The block diagram of Fig. 
 32 THERADAR EQUATION [SEC. 28 first amplifier stage-are taken into account, together with thefact that theinput impedance ofmicrowave receivers isnotunlimited, theoptimum value ofRturns out tobefinite. The condition R=Zis,infact, not unusual. 
 CROSSRANGEv PRINCIPLE  /FTEN OPTICAL AND 3!2 IMAGES OF THE SAME TARGET REGION DO NOT LOOK THE SAME TO A HUMAN OBSERVER #OURTESY OF 3CI4ECH 0UBLISHING  )NC  . 
 FIELD REFLECTOR ANALYSIS  METHOD IS BASED UPON RAY 
 ON WITH THE INCIDENT POLARIZATION IN THE PLANE OF THE PLATE   THEY YIELD THE EDGE 
 The resolution of the unfocused SAR does not depend on the size of the real antenna. (In a  sidelooking SAR the cross-range resolution is also called the ,along-track or azimuth  resolution.)  The limit on resolution due to operation in the far field can be overcome by correcting the  rcceived signal for the curvature of the spherical wavefront experienced when the target is  wrthin the Fresnel region of the synthetic array. At each "element" of the synthetic array  antenna a phase correction A4 = 2nx2/1R is applied, where x is the distance from the center of  the syntl~etic aperture. 
 M RESOLUTION WAS SPECTACULAR FOR ITS TIME  GIVEN THAT THE BEST RESOLUTION THAT COULD BE EXPECTED FROM AN OTHERWISE COMPARABLE REAL 
 They seem to be more detectable with radar having a moderate resolution rather than a high  resolution. 66 . 482 INTRODUCTION TO RADAR SYSTEMS  The backscatter from ice at high grazing angles is complicated by the relative ease of  penetration of radar energy into the ice. 
 A block diagram of the amplitude-comparison-monopulse tracking radar for a single  angular coordinate is shown in Fig. 5.8. The two adjacent antenna feeds are connected to the  two arms of a hybrid junction such as a "magic T," a " rat race," or a short-slot coupler. 
 W. Miller, Introduction to Adaptive Arrays , New York: John Wiley &  Sons, 1980. ch03.indd   34 12/15/07   6:03:35 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 15 of" Radar Handbook," M. I. Skolnik (ed.),  McGraw-Hill Book Co., Inc., New ~ork, 1970. 
 TOR 4HE #LASS 
 945–959, 1997. 145. M. 
 A shore-based HF 0TH radar can  cover large areas of the ocean and detect and track aircraft so as to provide air-traffic control.  For example. an 0TH radar with 120° angle coverage and a range interval extending rrom  1000 to 4~ km can survey an area of almost sixteen million square kilometers·. 
 TENTH THE 2/5 OF THE OTHER IN THIS DIMENSION  THEN THE MORE ACCURATE RADAR IN THIS DIMENSION WILL DOMINATE AND ESSENTIALLY DETERMINE THE RESULT !T LEAST IN STEADY STATE  IT IS RELATIVELY EASY TO PRODUCE THIS DOMINANCE BY ANY OF THE FUSION METHODS /F  MORE INTEREST IS THE CASE  WHERE THE RADARS ARE COMPARABLE IN TERMS OF ACCURACY AND UPDATE RATE  PRODUCING COMPA 
 •  Cooling system  design to maintain  feed temp can be a  challenge.•  A major driver, need  sophisticated modeling  to predict solar heating  throughout orbit. •  Passive cooling systems   are generally employed,  e.g., heat pipes. Vibration •  Typically not a major  driver. 
 Fung, M. R. Shah, and S. 
  RADAR 5SING MORE PULSES MAKES POSSIBLE NARROWER REJECTION NOTCHES AND THUS LESS BIAS FOR ESTIMATES OF PRECIPITATION WITH ZERO RADIAL VELOCITY &)'52%  2ESPONSE OF !32 
 This can be an integral part of  the radar hardware so as to rnininiize the problem of communicating the large number of  phase-shifter orders. 71'tie general-purpose radar-control cotnputer provides the beam-steering  cornputer with the desired elevatiori angle and azimuth angle. The beamsteering computer  tratislates this into cornniatids necessary for each phase shifter. 
 BAND MULTICAVITY KLYSTRON CAPABLE OF  -7 PEAK POWER AND  K7 AVERAGE POWER FOR USE IN A LINEAR ACCELERATOR 4HIS WAS A GREAT ACCOMPLISHMENT IN ITS TIME 4HE HIGH POWER  HIGH EFFICIENCY  GOOD STABILITY  AND WIDE BANDWIDTH AT HIGH POWER  OF THE MICROWAVE KLYSTRON AMPLIFIER HAVE CAUSED SOME RADAR DESIGN ENGINEERS TO SAY THAT THE KLYSTRON SHOULD BE THE FIRST MICROWAVE POWER SOURCE TO CONSIDER WHEN DESIGNING A NEW HIGH 
 DEPENDENT  o  3LIP 
 M. Dillard, “A moving-window detector for binary integration,” IEEE Trans ., vol. IT-13,   pp. 
 S. Stacy, “No evidence  for thick deposits of ice at the lunar south pole,” Nature , vol. 443, pp. 
 TER FREQUENCY CORRESPONDING TO THE CHANGE IN  @  WITH RANGE 7HEN THE ANTENNA IS POINTING  &)'52%  $EFINING GEOMETRY  @¼   ANTENNA POINTING ANGLE  @   LINE 
 Often PRFs are ambiguous in both range and doppler but unambiguous inside  the main beam and near sidelobes (i.e., there is only one range or doppler ambigu - ity interval in the main beam and near sidelobes). PRF selection is similar to A-A  MPRF. Usually fewer PRFs are used; four or five are typical.97 A range ambigu - ity may be in the main beam at low grazing angles. 
 J.: Doppler Radar, Proc. IRE, vol. 37, pp. 
 ( a) The Doppler rate; ( b) the derivative of the Doppler rate. Figure 14shows the residual spatial variance of the Doppler parameters after compensation based on the estimation results of the EMAM method. It can be seen that the ﬁrst- and second-order spatial variance of the Doppler rate and the ﬁrst-order spatial variance of the derivative of the Doppler rate are basically eliminated; only the higher order spatial variance is left, which does not affect the focus of the image. 
 Beam  switclling was performed separately from beam forming on both transmit and receive. This  example ofa radar based on multiple-beam-forming is a system that is probably more conlplex  tha~l would he needed now to accomplish the same radar mission.  Another approach to multiple-beam antennas utilized a planar lens array fed by a con-  stri~ined lens consisting of two connected hemispherical surfr~ces and a henlisplleric~~l feerl  surface.82 The details of this antenna will not be described here. 
 , /" Ó )NDEX OF 2EFRACTION  4HE TERM  REFRACTION REFERS TO THE PROPERTY OF A MEDIUM  TO BEND AN ELECTROMAGNETIC WAVE AS IT PASSES THROUGH THE MEDIUM ! MEASURE OF THE AMOUNT OF REFRACTION IS THE INDEX OF REFRACTION   N  DEFINED AS THE VELOCITY   C  OF PROPAGA 
 M. Herman, M. Kerker, and E. 
 1611] COMPENSATION FOR VELOC’I TY OF SYSTEM 655 Togetthegreatest cancellation ofanundesirable moving object, the first blind speed, v,,should bemade aslarge aspossible. For exampie, if U1is30times theradial speed oftheobject theresponse will be10percent ofthemaximum value, byEq. (20). 
 V., and D. D. Khandelwal: "GaAs FET Principles and Technology," Artech House, Norwood, Mass., 1982, pp. 
 In both these systems accuracy is inversely proportional to range from the radar, since a fixed angular error at the radar becomes an increas- ing linear error at increasing ranges. Homing provides the highest accuracy at the cost of complexity of the missile- borne hardware. Whereas the beam rider and command systems require only a single receiver in the missile, to sense the beam or receive commands, the hom- ing system perceives the target with its own radar (called the seeker), extracts tracking data from the received signal, and computes its own steering commands. 
 Billingsley, Low-Angle Radar Land Clutter: Measurements and Empirical Models . Norwich,  NY: William Andrew Publishing, 2002. 18. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar.  CIVIL MARINE RADAR  22.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 The minimum detection performance required in clear conditions is tabulated in  Table 22.1. 
   05,3% $/00,%2 2!$!2   {°x STRIKING THE GROUND AT A SCAN ANGLE OF  X  MEASURED FROM THE VELOCITY VECTOR 2AIN AND  CHAFF CLUTTER MAY ALSO BE LARGE WHEN THE MAIN BEAM ILLUMINATES A RAIN OR CHAFF CLOUD  -OTION DUE TO WINDS MAY DISPLACE ANDOR SPREAD THE RETURN IN FREQUENCY !LTITUDE 
 The first attempt with pulse radar at NRL was at a frequency of 60 MHz. According to  Guerlac! the first tests of the 60-MHz pulse radar were carried out in late December, 1934,  and early January, 1935. These tests were" hopelessly unsuccessful and a grievous disappoint­ ment." No pulse echoes were observed on the cathode-ray tube. 
 Rept. 8321,  August 20, 1979. 23. 
 THRESHOLDING  IN THIS CASE  SUCCESSFULLY ELIMINATES LARGE NUMBERS OF CLUTTER DETECTIONS WHILE PRESERVING MOST TARGET DETECTIONS AFTER 7 ' "ATH ET AL  . Ç°ÓÈ  2!$!2 (!.$"//+  OF THIS PROCESS WHEN LARGE NUMBERS OF RAIN CLUTTER DETECTIONS ARE POTENTIALLY OVERLOAD 
 E. Morriello: Development of a Multistatic Measurement System, IEEE Int. Radar Conf., pp. 
 3 Boxcar --t- +  Figure 4.19 Block diagram of MTI radar using range gates and filters. Ronge  gate  No. 1 +  Following the doppler filter is a full-wave linear detector and an integrator (a low-pass  filter). 
 Geophys. Res. Oceans 1996 ,101, 6651–6667. 
 1971 12.Piltack.U..andR.A.Handy: Progress inHelixTraveling-wave TubesforRadarSystems, MicrowQl'e SystemNews.vol.5.pp.6975.February/March, 1975. I.lNnlos.F.J.:PresentStaleofArtinHighPowerTraveling-Wave Tubes.pI.l,MicrOlvar'e i..vol.2. rrJ1JR.Decemher.1959;pI.IIfiticrow(/('l' i..vol.3.pp.4652,January. 
 59. McLoughlan, S. D., M. 
   -4) 2!$!2  Ó°£ .OTE THAT THE CLUTTER IN &IGURE  B IS VERY SPOTTY IN CHARACTER  INCLUDING THE  STRONG FIXED 
 AREA SURFACE FEATURES  SUCH AS DETERMINATION OF SEA ICE COVERAGE  MAPPING THE BOUNDARIES BETWEEN THE PRINCIPAL ICE ZONES OF 'REENLAND  OR GLOBAL ESTIMATION OF TROPICAL DEFORESTATION )N ALL SUCH APPLICATIONS  THE EMPHASIS IS ON MEASUREMENT OF MEAN REFLECTIVITY OVER LARGE AREAS  RATHER THAN MAPPING FINE SPATIAL DETAIL 4HESE RADARS TYPICALLY HAVE RESOLUTIONS ON THE SCALE OF S OF KILOMETERS  SUP 
 3.14 Dual-gain IF stage.FIG. 3.15 Dual-gain-stage voltage character- istic. The size of the PROM can be substantially reduced by comparing the two variables to determine the larger (L) and smaller (S): Iog2 (I2 + Q2) = Iog2 L + Iog2 (1 + S2IL2) (3.16) The latter term of Eq. 
 TION  AND THE RELATIVE ANGULAR SPEEDS 4HE JAMMER TRACK IS INITIALIZED BY USING THE FIRST TWO MEASUREMENTS PROVIDED BY THE RADAR u *AMMER POWER LEVEL ESTIMATION  !N ESTIMATE OF THE POWER LEVEL CAN BE OBTAINED BY  THE FIRST 
 We have seen that the characteristics of the receiving equipment which influence this matter most profoundly are the noise figure and bandwidth ofthe receiver, the integrating properties ofthecathode-ray tube screen, and thetype ofdisplay. Toa lesser extent the cathode-ray-tube spot size and the scale-factor ofthe display also play arole. Section 12.8 points out methods ofincreasing the signal discernibility inthe presence ofvarious forms ofradiant interference bytaking advantage ofdifferences between the desired and the undesired signals, and shows that tosome extent these same techniques aid indistinguishing apoint target from more diffuse ones. 
 The larger the value  of m, the more constrained will be the fluctuations. The limit of tn equal to infinity corresponds  to the nonfluctuating target.  The chi-square distribution is a mathematical model used to represent [tie statistics of the  fluctuating radar cross section. 
 This type of processing—or similarly derived from the generalized likelihood ratio  test (GLRT)—has been used in some practical radar. Furthermore, any self-respecting radar system should make the operator aware of  higher noise levels due to jamming even though they may not be visible on the CFAR  display; the act of performing CFAR should not exclude the operator from knowing  that jamming is present and that the detection threshold has been raised. 24.10 OPERATIONAL-DEPLOYMENT  TECHNIQUES To this point in the chapter, only electronic ECCM techniques have been considered. 
 Also, adequate drainage should be provided to prevent the  accumulation of water in the reflector. Ice coating a reflector surface does not usually cause a  problem. When ice is in the process of melting, however, the water surface can distort the  pattern and in some instances can completely destroy the main beam. 
 low.:power.! applications thisdecrease insensitivity mightbe ••• c••~••'.tolerated sinceitcan,becompensated byamodest'increase inantenna aperture and/or additional transmitt~r power,But:for'm~"imum efficiency withCWradar,thereduction in sensitivity causedbythesimple dopplei:r~ivefwithzero IF,cannotbetolerated . .Theeffe.ctsofflicker,:~ol~e~it~:'~Y~~m~in then~~·alsuper.heterodyne receiver b~using anmtermedlate frequencyJ~lgh~eJ1oughJo·render. theflickernOisesmallcompared Withthe normalreceiver noise~:'Thk, re~uli~ifrom: the'inverse.frequency dependence offlickernoise.,."....... 
 TICAL GROUPS OF PULSES  EACH GROUP CONSISTING OF  .    hSINGLE 
 GATE STEALERS BY SWITCHING RADAR MODES !NGLE 
 20.50, in that after low-noise am- plification to establish the system noise figure, an RF quadrature hybrid device is used to combine the delta and sum beam signals 90° out of phase, i.e., as 2 + y'A. The purpose of this combining in the difference channel is to bring the signal strength in the difference channel to approximately the same amplitude at that in the sum channel. This causes unavoidable receiver nonlinearities to have nearly the same effect in the two channels, resulting in less degradation in accuracy per- formance attributable to receive-string nonlinearities. 
 It is also potentially useful for vulnerable vessels such as chemical carriers to ensure  that appropriate action in heavy weather can be taken, particularly at night or in poor  visibility. Ocean oil rig operations can also benefit from such systems. Information  can be displayed to the user in the form of digital readouts of the primary parameters,  as well as graphically displayed data. 
  &IGURE   USES A VERTICAL ARRAY TO PRO 
 ch19.indd   19 12/20/07   5:38:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 
 As the inner conductor rotates the wavelength in the linc  varies, causing the beam to scan.  7.5 LENS ANTENNAS  The most common type of radar antenna is the parabolic reflector in one of its varioi~s forms.  The microwave paraboloid reflector is analogous to an automobile headlight or to a searcti-  light mirror. 
 OUSLY             ETC 4HIS  LEAPFROG SEQUENCE IS REQUIRED TO CAPTURE ALL RETURNS  IN THE COMMON 
 Ideal ambiguity diagram If there were no theoretical restrictions, the ideal ambiguity diagram  would consist of a single peak of infinitesimal 'thickness at the origin and be zero everywhere  else, as shown in Fig. 11.7. The single spike eliminates any ambiguities, and its infinitesimal  412INTRODUCTION TORADAR SYSTEMS complex-modulation function whosemagnitude Iu(e) 1istheenvelope oftherealsignal.andfo isthecarrierfrequency. 
 *  The field of space-based remote sensing radars is subject to rapid change. This chapter provides the view from  the early 21st century. Readers are encouraged to seek currently topical information through online resources. 
 It could be seen that the targets were focused at di ﬀerent range positions due to their di ﬀerent heights. The targets in Figure 7b were all well focused, and had lower azimuth sidelobes and better azimuth resolutions than those in Figure 7a. 5DQJH P $]LPXWK P       DEF  5DQJH P $]LPXWK P       DF E   (a) ( b)  Figure 7. 
 CF As can be used as a power booster following a magnetron oscillator, as the high-power  stage in master-oscillator power-amplifier (MOPA) transmitters with other CF As or a TWT  as the driver stage, or as t.he individual transmitters of a high-power phased-array radar. RADAR TRANSMITTERS 209  The crossed-lick! amplifier is based 011 tile same principle of electronic interaction as tile  magnetron. Thus, its characteristics resemble those of the magnetron, and many CF As are  even similar in physical appearance to a magnetron. 
 Specular Scatterers.  A specular scatterer is any target surface that is oriented per - pendicular to the line of sight to the radar. Flat surfaces offer particularly large echoes  in the specular direction, but the echoes drop off sharply away from that direction. 
 MTI RADAR  2.796x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 an A/D converter sampling rate as given by Eq. 2.60, but other values will result in an   available Nyquist bandwidth less than fAD/2. This is shown in Figure 2.84 where  the normalized Nyquist bandwidth is shown as a function of the relative A/D converter  sampling rate. 
 For this reason, Faraday rotation compensation should be considered. On the other hand, Faraday rotation could also be retrieved from distorted echoes. Moreover, combining Faraday rotation with the radar parameters and the model of magnetic ﬁeld, we could derive the total electron content (TEC) along the signal path. 
 LIFED COMPONENTS SUCH AS MAGNE 
 K. Barton, CW and Doppler  Radars,  Section IV–11, V ol. 7. 
 The delay time can be varioo  by changing either the number of stages (a capacitive storage element and its associated  switch) or by changing the switching frequency controlled by a digital clock. CCDs provide a  similar function except that charge packets are transferred to adjacent potential wells by  clocked voltage gradients. The sampling frequency must be such as to obtain one or two  samples per range resolution cell. 
 S. Baker, and S. M. 
 ON 
 It is necessary to operate these lines below about 5 MHz if differential delays of over 50 JJLS are required. Aluminum lines have a midband delay of 7 to 10 jxs/in. Steel strip delay lines have high losses but operate at higher center frequen- cies, permitting wider bandwidths. 
 Okamoto, M. Shimada, and S. Niwa, “Measurement of microwave backscattering  signatures of the ocean surface using X band and Ka band airborne scatterometers,” J. 
 I. Skolnik (ed.). McGraw-Hill  Rook Co .. 
 WIDTH TO AVOID A LOSS IN 3.2 CAUSED BY TARGET ECHOES THAT ARE NOT CONTAINED WITHIN THE REFERENCE WAVEFORM  %QUAL 4RANSMIT AND 2EFERENCE 7AVEFORM ,&- 3LOPES  &OR THE CASE WHERE THE  TRANSMIT AND REFERENCE WAVEFORM ,&- SLOPES ARE EQUAL  @    @  2   THE )& SIGNAL IS AN  UNCODED PULSE WITH FREQUENCY OFFSET GIVEN BY   DA T TFFD2 
 705-706, December, 1957.  50. Payne-Scott, R.: The Visibility of Small Echoes on Radar PPI Displays, Proc. 
 If a reflector is illuminated with a group of four feed elements, a conflict arises . (a) <b> FIG. 6.17 Extended feeds off the focal plane, (a) Geometry. 
 It also requires an application where a short minimum range  is not important since reception cannot take place during the transmission of the burst of . 318 INTRODUCTION TO RADAR SYSTEMS  pulses. Thus this approach would be suitable for radars whose targets are at long range, such  as satellite surveillance or BMD (Ballistic Missile Defense). 
 Such a mount, however, transfers the problem of excessive accelerations to some  other direction; in this case, in the direction of the elevation axis. A three-axis mount avoids  the problem of excessive acceleration.  The two-axis mount of (d) is similar to (c) except that it is arranged to provide roll  stabilization. 
 SAR imaging of eddies is mainly determined by four mechanisms. The ﬁrst one is the shear-wave mechanism [ 8–12], which is associated with the wave/current interactions in the zones of current shear, and the eddy manifests itself in the form of regions of modulated normalized radar cross section (NRCS) and twisted into spirals in SAR images. The second one is the ﬁlm mechanism [ 8–10,13], which is caused by the suppression of gravity-capillary waves by surface ﬁlms of natural origin. 
 TIVE WAVELENGTH PROJECTED ONTO THE GROUND PLANE IS SLIGHTLY DIFFERENT FOR THE TWO CASES )NTERFERENCE IS SUPPORTED ONLY IF THE RANGE BANDWIDTH OF THE RADAR SIGNAL IS SUFFICIENT TO SPAN THE PROJECTED WAVELENGTHS  WHICH  BECOMES MORE DEMANDING AS THE ORBIT SEPARA 
 Typically, thebeamcanbeswitched inseveralmicroseconds, butitcanbeconsiderably shorterifdesired. Multiple, indepelldent beams.Asingleaperture cangenerate manysimultaneous independen t beams.Alternatively, thesameeffectcanbeobtained byrapidlyswitching asinglebeam through asequence ofpositions. Potetttialfor largepeakand/oraveragepower.Ifnecessary, eachelementofthearraycanbefed byaseparate high-power transmitter withthecombining oftheoutputsmadein"space.. 
 4.1) shows thetwo beams and thedirection ofrotation ofthe antenna mount. The 45” Vreproduces the value of theheight asthehorizontal distance between thevertical and slant beams attheappropriate range and height. This isexpressible interms ofD, theground range tothetarget. 
 RECEIVE ONLY ,/2/  SYSTEM CONCEALS THE LOBING RATE FROM A POTENTIAL JAMMER  #ONICAL SCAN AND SEQUENTIAL LOBING ARE GOING TO BE REPLACED BY THE MONOPULSE TECH 
 I.  Skolnik (ed.), McGraw-Hill Book Co., New York, 1970.  58. 
 ¤ ¦¥³ µ´)MP L    WHERE THE  AI ARE DROPLET RADII   Q IS THE DENSITY OF WATER  AND )M IS THE IMAGINARY PART  6ALUES OF  + FOR ICE AND WATER CLOUDS  ARE GIVEN FOR VARIOUS WAVELENGTHS AND TEMPERA 
 34, pp. 528-578, August 1946. 7. 
 1 1Mw-4.v-Video Intensity Focus amplifier control control FIG. 13.41.—Simple A-acopa.;6Sk > ‘470k,. Trigger 4 I I I I I1 .Automatic Square turnoff wave ASawtooth ~Inverter c ampl(fler generatorgenerator +2000V v,V3V4v V25. 
 7ATT )T WAS SEEN  THAT RADAR ON COM 
 TO 
 "ECAUSE THE ANTENNA REPRESENTS THE TRANSDUCER BETWEEN THE RADAR AND THE ENVIRON 
 34. Love, A. W.: Scale Model Development of a High Efficiency Dual Polarized Feed for the Arecibo  Spherical Reflector, IEEE Trans., vol. 
 SIDELOBE ANTENNA IS ONE OF REDUCING EACH OF THE AMPLITUDE ERRORS TO A FEW TENTHS OF A DECIBEL AND THE PHASE ERRORS TO A FEW DEGREES 4HE FEWER THE NUMBER OF ELEMENTS USED  THE TIGHTER THE TOLERANCE BECOMES 4HE INDIVIDUAL EFFECTS OF PHASE AND AMPLITUDE ERRORS AND FAILED ELEMENTS ARE SUM 
 andH.Gravestein: TheRadarBackscatter fromSelected Agricultural Crops.IEEETrailS..vol.CiE-I2.pp.70-77,April,1974.. 54. Bush, T. 
 13. V . G. 
 (ed.): Special Issue on Active and Adaptive Antennas, IEEE Tratls., voL AP-12, no. 2,  March, 1964.  143. 
 http://en.wikipedia.org/wiki/Venera_16 4. http://www2.jpl.nasa.gov/magellan/ 5. http://filer.case.edu/ ∼sjr16/advanced/20th_close_clementine.html 6. 
 14.7 MINIMIZATIONOFFEEDTHROUGH All major ground-based CW radars have two antennas to minimize spillover. Iso- lation may be improved further by the use of various absorbers or of an inten- tional feedthrough path that is adjusted in phase and amplitude to cancel spillover energy. In free space such solutions are all that would be required. 
 GROUND SURFACE INTERACTION 3OME OF THE ANCILLARY REQUIREMENTS OF AN OPERATIONAL '02 SYSTEM NEED TO BE CON 
 The defocused ship targets of TerraSAR-X images are depicted in Figure 5. The two ships are numbered as ship01 and ship02. The ships are still blurred and defocused due to their motion, and need motion compensation. 
 The first method ofestimation istocalculate the largest possible ground return onthe assumption that the return isfrom amountain so large astofillthe beam completely. Such amountain iscertainly possible, and assuming ittobehemispherical itsreturns will belarger than those from atarget ofcross section ainthe ratio r2A/k’u with A the dish area. Inthe present case, this comes out atabout 110 db. 
 Thus, the loss in signal-to-noise ratio associated with weighting by the usual mismatching tech- niques is eliminated. If a symmetrical FM modulation is used with time weighting to reduce the frequency sidelobes, the nonlinear-FM waveform will have a near- ideal ambiguity function. A symmetrical waveform typically has a frequency that increases (or decreases) with time during the first half of the pulse and decreases (or increases) during the last half of the pulse. 
 When large and small slots are alternated, as in the rising-sun  niagrictron structure of Fig. 6.2h. stable oscillation can occur in the ~t. 
 Earth Obs. G éoinf. 2019 ,75, 54–67. 
 The symmetrical arrangement shown has significant blockage, but offset geometries  mitigate feed blockage. In modern reflector antenna design, combinations and variations of these basic  types are widespread; however, design goals generally stress beam gain(s), shape(s),  location(s), etc., while stipulating minimal losses and low sidelobe levels. Paraboloidal Reflector Antennas. 
 Thechiefcharacter­ isticoftheTWTofinteresttotheradarsystemengineer isitsrelatively widebandwidth. A widebandwidth isnecessary inapplications wheregoOdrange-resolution isrequired orwhere itisdesiredtoavoiddeliberate jamming ormutualinterference withnearbyradars.Although lowpowerTWTsarecapable ofoctavebandwidths, bandwidths oftheorderof10to20 percentaremoretypicalatthepowerlevelsrequired forlong-range radarapplications. The gain,efficiency, andpowerlevelsofTWTsarelikethoseoftheklystron; but,ingeneral, their valuesareusuallyslightlylessthancanbeobtained withaklystron ofcomparable design. 
 that an amplitude ripple results in time sidelobes around the compressed pulse. Pair 8 of Table 10.7 shows that a phase ripple also results in time sidelobes around the compressed pulse. Figure 10.20 shows the amplitude and phase tolerances versus sidelobe level. 
 Since itvaries considerably with individual tubes ofthesame type and manufacture itisdesirable toquote average figures. Some representative values aregiven inTable 12.1. Ithas long been realized that alarge portion ofthe shot noise ina pentode isdue totheinterception ofelectrons bythescreen grid. 
 III and ASV Mk. VI radars was documented in various trials undertaken by TRE and CCDU, as discussed in the earlier chapters. CCDU also undertook a series of trials aimed at directly comparing the two radars[2]. 
 #HEBYSHEV DISTRIBUTION CAN BE FOUND IN THE ANTENNA LITERATURE !N EXAMPLE OF A FILTER DESIGN FOR A #0) OF  PULSES AND A SIDELOBE REQUIREMENT OF  D" IS SHOWN IN &IGURE  4HE PEAK FILTER RESPONSE CAN BE LOCATED ARBITRARILY IN FREQUENCY BY ADDING A LINEAR 
 Numerical Experiment In order to validate the mathematical derivation of asteroid’s ISAR geometry, kinematics and signal models, a numerical experiment with a signal model of one microburst is carried out based on the following pulsar’s signal parameters: central channel frequency fc=10.075 GHz; frequency channels bandwidth ΔF=150 MHz; spectral resolution Δf=1MHz; fmin=10 GHz, fmax=10.15 GHz; number of frequency channels R=150; main pulses time repetition period Tp=0.033 s, microburst time width T=10−6s; number of range samples in microburst K=128; sample’s time width ΔT=0.8×10−8s; number of azimuth measurements N=128 in one imaging segment deﬁned by the number of main pulses used for aperture synthesis; initial coordinates of asteroid’s detection x0/prime=1 km, y 0/prime=350 km, z0/prime=103km; distance to the mass-center R0/prime=1.06×106km; asteroid’s velocity V=35 km/s; velocity anglesα=π/6,β=π/4,γ=π/2. The geometry of the asteroid is depicted in a 3-D grid with dimensions 64×64×64, and grid cell dimensions ΔX=ΔY=ΔZ=0.5 m, Relative intensity of scattering points isag=10−3. In order to obtain an asteroid’s image of high resolution the apparent rotation angle between the asteroid’s vector velocity and mass-center’s line-of-sight vector has to be no less than 100. 
  D" IN THE CLUTTER REJECTION NOTCH RELATIVE TO THE PEAK TARGET  RESPONSE  OF THE MOVING 
 The darkened fan-shaped area extending upward over the island represents  the radar’s probability of detection of a certain target as the radar sweeps southward  over the island. For a target located in the forefront of the island and at a sufficiently  low altitude, the display shows the target is not detectable by the radar as the target is  masked by the intervening terrain. ch26.indd   20 12/15/07   4:53:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 105, pp. 93-108, March, 1958.  11. 
 LOOKING RADAR LIKE THAT SHOWN IN THE EXAMPLE IS NOT RECTANGULAR BUT  RATHER HAS THE SHAPE OF THE ANTENNA ALONG 
 MUM VARIANCE ACROSS THE  - DETECTIONS  OR USING MAXIMUM LIKELIHOOD TECHNIQUES  4HE COMPUTED RADAR CROSS SECTION 2#3  OF CORRELATIONS CAN ALSO BE USED IN THE   CORRELATION PROCESS TO REJECT SIDELOBE DISCRETE DETECTIONS AS DESCRIBED IN 3ECTION  POSTDETECTION 34#  4HE GHOSTING PROBLEM CAN BE MITIGATED FURTHER BY A COMBINATION OF DOPPLER ANDOR  MONOPULSE BINNING 2ESOLVING THE DOPPLER AMBIGUITIES FIRST PRIOR TO RANGE CORRELA 
 Waveforms consisting of more than two phases may also be used.31' The phases of the subpulses alternate among multiple values rather than just the 0° and 180° of binary phase codes. The Frank polyphase codes33 derive the sequence of phases for the subpulses by using a matrix technique. The phase sequence can be written as <|>M = 2m(n - I)//*2, where P is the number of phases, n = O, 1, 2,..., P2 - 1, and / = n modulo P. 
 339-345. May, 1973. 274 INTRODUCTION TO RADAR SYSTEMS  18. 
 60.Jay,F.(ed-in-ch.): "IEEEStandard Dictionary ofElectrical andElectronics Terms," 2ded.,Inst.of Electrical andElectronics Engineers, Inc.,NewYork,1977. 61.Anonymous: NewsiteminAviation WeekandSpaceTechnology, vol.109,no.13,p.61,Sept.25,1978. 62.Tenenholtz, R.:Designing Megawatt DiodeDuplexers, Microwave J.,vol.21,pp.30-34,Dec.,1978, andvol.22,pp.63-68,Jan.,1979. 
 Both contractors also devised measurement techniques that would provide a 50-mil rms accuracy required for the measurement of antenna deformation. General Dynamics has designed space-erectable antennas and parabolic graphite-epoxy reflectors for space applications.43'46 A 2.44-m-diameter reflector was built and tested. It has a surface tolerance of 0.0635 mm rms and a specific mass of 4.4 kg/m2. 
 pp. 1229 1232. October. 
 9). Elevation Scanning.—The height-finding methods sofar described arealllimited inaccuracy, inspeed ofheight-reading, orinthenumber of targets which can bedealt with atonce byasingle height-finding radar. The advantages ofasystem inwhich anarrow beam scans inelevation and the signals are displayed directly onanintensity-modulated tube whose coordinates arederived from range and elevation angle areappar- ent. 
 Queen, J. D. Wilson, and J. 
 It is the preferred technique for precision tracking. However, both monopttlse and  conical-scan radars are degraded equally by the wandering of the apparent position of the  target (glint).  182INTRODUCTION TORADAR SYSTEMS resolution isolatestheindividual scattering centersandtherefore eliminates theglintproblem. 
   THOMSONA FLASHNET  * % 3ALAH AND * % -ORRIELLO  h$EVELOPMENT OF A MULTISTATIC MEASUREMENT SYSTEM v IN  )%%%  )NTERNATIONAL 2ADAR #ONFERENCE    PP n  h-ULTISTATIC MODE RAISES RADAR ACCURACY v  !VIATION 7EEK AND 3PACE 4ECHNOLOGY   PP n   *ULY     * 7URMAN  3 (ECKMAN  AND $ "OCCIPPIO  h! BISTATIC MULTIP LE 
 28 to 23.29.     I_3 range equation, 23.5 to 23.6 SAR, 23.17 scattering coefficient, 23.22 to 23.25 surface clutter in, 23.22 to 23.26 target cross section, 23.19 to 23.21 target location, 23.17 to 23.19 with TV transmitter, 23.29 to 23.31 Blind speeds, 2. 9 to 2.10 Block diagram digital receiver, 25.2 medium PRF air-to-air pulse doppler, 5.17 monopulse tracking radar, 9.4 to 9.5 Moving Target Detection, 2.6 to 2.7 multifunctional fighter aircraft radar, 5.3 pulse compression, 8.1 to 8.2 pulse doppler, 4.11 radar, 1.3 SBR altimeter, 18.40 Bodies of revolution radar cross section, 14.39 to 14.40 Bragg scatter, 15.2, 15.28 to 15.32, 15.38, and ground echo, 16. 
 1024, April. 1946.  56. 
 180-35. 70. J. 
 Sensors 2019 ,19, 2921. [ CrossRef ][PubMed ] 10. Fang, Y.; Wang, B.; Sun, C.; Wang, S.; Hu, J.; Song, Z. 
 When the horns and switch arerotated the effect istocause the beam ofthe antenna toscan a10°azimuth sector each FIG. 9.25.—Perspective ofhorn, reflector, andfeed ofSchwarzschild antenna used in AN/MPG-l. time ahorn runs itsW“ course. 
 prepare the individual chapters. I appreciate their hard work in commit- ting to writing their knowledge and experience, and I am grateful that they have shared this with us. Merrill Skolnik . 
 The R4 loss is the fourth power of range to the target in meters, expressed in  decibels. R4 + L adds nondeviative absorption, deviative absorption, sporadic-E obscu - ration, and ground-reflection losses if there is more than one hop. The sharp increase in  loss just before 2000 nmi is caused by transition from one to two hops; for two hops,  the lossy D region is transited twice as many times, ground-reflection loss is added, and  required operation at a lower frequency increases loss. 
 C, M.I.T. Press, Cambridge, Mass., 1972. 27. 
 To evaluate s 0 the  ratio of transmitted to received power is required. The system depicted in Figure 16.12 a  measures transmitter power and receiver sensitivity separately. The transmitter feeds an  antenna through a directional coupler so that a portion of the energy may be fed to a  power meter. 
 and G. D. Thayer: "A World Atlas of Atmospheric Radio  Refractivity." L1.S. 
 The relationship between the gain and the beamwidth of an antenna depends on the  distribution of current across the aperture. For a "typical" reflector antenna the following  expression is sometimes used:  where OB and +B are the half-power beamwidths, in degrees, measured in the two principal  planes. This is a rough rule of thumb that can be used when no other information is available,  but it should not be a substitute for more exact expressions that acount for the actual aperture  illumination. 
 TO 
 tto. 66  on .4dl*atrced Rudur Systert~s, November. 1970. 
  
 The maximum insertion loss was 40 dB. Other designs have  resulted in pulse widths as long as 100 µs and pulse-compression ratios as high as 10,000.22  The SAW dispersive delay line is one of the more important of the many devices that have  been employed for pulse-compression radar. They have been claimed to be simple, low cost,  '1'11111111111111111111, 1 Figure H.18 lnterdigital transducer (nondispersive) showing  overlap of comb fingers, or electrodes, to provide an amplitude  weighting along the pulse. 
 Selection of the Detection Threshold.  The presence of a jamming signal can  increase the number of false alarms and wrong plot-track associations up to an unac - ceptable level, thus increasing significantly, the probability of loosing a target under  track. It is, therefore, important that the radar receiver be equipped with a CFAR. 
 Advances in mixer technology have resulted in a wide variety of commercially  available devices employing balanced, double balanced, and double-double balanced  topologies covering a wide range of RF, LO, and IF frequencies and a range of per - formance characteristics. Mixer Spurious-Effects Chart.  A graphical display of mixer spurious compo - nents up to the sixth order is shown in Figure 6.2. 
 AGING  SAY  FOUR PIXELS TOGETHER AFTER DETECTION 4RANSMITTING MORE BANDWIDTH THAN NEEDED FOR RANGE RESOLUTION ACCOMPLISHES THIS PURPOSE WITHOUT LOSS OF NEEDED SPA 
 G.: Postdetection Integration Loss for Logarithmic Detectors, JEEE Trans., vol. AES-8,  pp. 386-388, May, 1972. 
 •  Cooling system  design to maintain  feed temp can be a  challenge.•  Can be a major  driver. •  Radars are  typically high  power. •  High power  densities at  feed or feed  array are  common. 
 2.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 Because of the imprecision in predicting s 0 and h, these equations do not include  an antenna beam-shape factor. For the measurement of the reflectivity of rain, refer - ences on radar meteorology present more precise equations.13 In addition to distributed clutter targets, there are many targets that appear as  points,  such as radio towers, water tanks, and buildings. These point targets typically  have a radar cross section of 103 to 104 m2 with typical densities as shown later in  Figure 2.18. 
 Byheterodyning inamixingelementtheechosignalreceived intheforeandaft beams, the dopplerfrequency isextracted. Thedifference frequency resulting fromthemixing operation istwicethedoppler frequency. Astabletransmitter frequency isnotneededinthis systemasitisinthecoherent system.Coherence isobtained onarelativebasisintheprocess ofcomparing thesignalsreceived fromtheforward andbackward direction. 
 4.35 show the improvement in MTJ processing that is theo­ retically possible with DPCA and a three-pulse delay-line canceler. (Note that the DPCA  corrects only one canceler of a multiple-stage MTl.63) The curve for x = 0 applies for no  platform motion and represents the maximum improvement offered by an idea platform­ motion cancellation method. It is seen that when the clutter spectral width is small, as for  overland clutter, a significant improvement is offered by DPCA. 
 Ultraviolet Radiation, and Radiation from Lasers and Television Receivers-An An- 11olaled Bihliography," U.S. Dept of Health, Education, and Welfare, Public Health Service Publica­ tion no. 999-R H-35. 
 Urkowitz, H.: Analysis and Synthesis of Delay Line Periodic Filters, IRE Trans., vol. CT-4, pp. 41 -53,  June, '1957. 
 ORDER DELAY 
 ING IN %Q   ARE SHOWN IN &IGURE  )NITIALLY  AN AIRCRAFT OF OPPORTUNITY HAS THE HIGHEST ASSOCIATION PROBABILITY HOWEVER  A FIRM DECISION IS NOT MADE BECAUSE  0MAX  DOES NOT EXCEED  0NEXT BY THE PROBABILITY MARGIN !FTER THE TH $& DETECTION  THE  EMITTER IS FIRMLY CORRELATED WITH THE CONTROL AIRCRAFT (OWEVER   AT THE TH $& DETEC 
 306 INTRODUCTION TO RADAR SYSTEMS  waveguide may be used for the same purpose. If wide-angle scan is not required, the open­ ended waveguides may be flared to form a horn with greater directivity. An array of open­ ended waveguides quite often will be covered with a thin, flat sheet of dielectric to serve as a  means for better matching the array to free space, as well as to act as a radome to protect the  array from the weather. 
 TABLE 18.9  Radar Sounders Instrument URL Spacecraft Years Objective Frequency ALSE 1 Apollo-17 1972 Lunar subsurface 5, 15, 150 MHz MARSIS 2 Mars Express 2003– Mars subsurface 1.8, 3, 4, 5 MHz SHARAD 3 MRO 2005– Mars subsurface 15 - 25 MHz LRS 4 SELENE 2007 Lunar subsurface 5 MHz PR 5 TRMM 1997– Rain 13.8 GHz MARSIS 6 Mars Express 2003– Mars ionosphere 0.1–5.4 MHz CPR 7 CloudSat 2006 Earth cloud profiles 94 GHz DPR 8 GPM – Rain 13.6, 35.5 GHz 1. http://nssdc.gsfc.nasa.goc/database/MasterCatalog?sc =1972-096A&ex =4 2. http://sci.esa.int/science-e/www/area/index.cfm?fareaid =9 3. 
 POL DATA SET CAN BE TRANSFORMED TO REPRESENT ALL POSSIBLE COMBINATIONS OF TRANSMIT ANDOR RECEIVE POLARIZATIONS 0ITFALLS AWAIT THE UNWARY  HOWEVER  INCLUDING TRICKY COORDINATE CONVENTIONS   AN INITIALLY CONFUSING VARIETY OF hSTANDARDv FORMS FOR .   30!#% 
 R-F COMPONENTS, ...................391 11.1 The R-f Transmission Problem 391 11.2 Coaxial Lines ..... .393 11.3 Waveguide ... .398 11.4 Resonant Cavities. 
 This is particularly useful in cloudy environments, but radar is also useful  even in clear weather because performance is independent of time of day so sun angle  does not matter. Moreover, radar ground signatures differ from those in the visible and  infrared. Radar has been applied to agriculture, forestry, geology, hydrology, urban  geography, regional studies, oceanography, and ice mapping. 
 Since the roughness that affects radar must be measured in wavelength units, a surface smooth at long wavelengths may be rough at shorter ones. This is illustrated in Fig. 12.31,94 which shows these effects with measurements from plowed fields. 
 96. F. O’Hora and J. 
 TORS PRIOR TO RETRIEVING THE DESIRED INFORMATION 4HE CONVENTIONAL MODE IS USED FOR THE OPEN OCEAN FOR CALIBRATION AND SEA 
 change iri signal-to-rioise ratio is much greater than this for a given change in detection  probability, as discussed in Sec. 2.8.) Also, the signal-to-noise ratio required for detection is  not a serisitive functioti of the false-alarm time. For example, a radar with a 1 -MHz bandwidth  requires a signal-to-rioise ratio of 14.7 dl3 for a 0.90 probability of detection and a 15-min  false-alarni irne. 
 Thisunit would have been designed for a speci ﬁc transmitter frequency and would have introduced additional losses if the transmitter frequency was appreciably off tune. Aerial switch unit type 98A rotated at 600 rpm or 10 rps. The switch segments each operated over 45 °, giving an effective switch rate of 20 rps, the same as in the internal aerial switch unit in the receiver. 
 SUPPORT  BLOCKAGE TO SOME DEGREE &OR CENTER 
 LEVEL /NE CAN SEE THE EFFECTS OF MULTIPATH INTERFERENCE BETWEEN A RANGE OF  AND ABOUT  NAUTICAL MILES "EYOND THE MULTIPATH INTERFERENCE REGION  ONE CAN SEE A MAJOR FALL OFF OF SIGNAL 
 In order to reduce the level of additive white Gaussian noise in signals and enlarge the signal to noise ratio in the ﬁnal image, coherent summation of multiple complex images is applied. To prove the correctness of the geometry, signal models and theoretical analysis, results of numerical experiments are provided. Keywords: passive ISAR asteroid imaging; pulsar emission signal modeling 1. 
 An example of a waveform for a medium-range radar that detects  aircraft might be described as a short pulse one millionth of a second in duration  (one microsecond); the time between pulses might be one millisecond (so that the  pulse repetition frequency is one kilohertz); the peak power from the radar transmit - ter might be one million watts (one megawatt); and with these numbers, the average  power from the transmitter is one kilowatt. An average power of one kilowatt might  be less than the power of the electric lighting usually found in a “typical” classroom.  We assume this example radar might operate in the middle of the microwave† fre- quency range such as from 2.7 to 2.9 GHz, which is a typical frequency band for civil Chapter 1 *  This chapter is a brief overview of radar for those not too familiar with the subject. 
 E. Austin, D. J. 
 P. Clark, Chapter 12 in Radar Handbook , M. I. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 7 .14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 identify the presence of narrow-pulse interference, a detection performance approxi - mately halfway between the limiting and nonlimiting ratio detectors can be obtained. 
 The  parameter a. is called the effective time duration or the signal, and (a./21t)2 is the normalized  second moment of s2(r) about the mean epoch, taken to bet= 0. If the mean is not zero, but  some other value t0, the integrand in the numerator of(ll.28) would be (2n)2(t -c0)2s2(t). 
 S. Kogon (MIT, Lincoln Laboratory, U.S.). ch24.indd   58 12/19/07   6:01:16 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 φi(PQ,1)φi(PQ,2)... φi(PQ,MN)⎤ ⎥⎥⎥⎥⎥⎥⎥⎦, (3) where φi(pq,mn)=exp{− j4πfp c(xmcos(θq)+ ynsin(θq))}. 29. 
 A conventional short-pulse radar may be desired for the  following purposes:  Range resolutio11. It is usually easier to separate multiple targets in the range coordinate than  in angle.  Ra11ge accuracy. 
 Theresolution cellisnotlikelytobecompletely fiiledatlongrangeor whenthebeamisviewing theedgeofaprecipitation cell.Ifthe"brightband"(tobedescribed later)iswithintheradarresolution cell,theprecipitation alsowillnotbeuniform. Whentheradarwavelength islargecompared withthecircumference ofascattering particleofdiameter D(Rayleigh scattering region), theradarcrosssection is (13.17) where IK12=(£-1)/(£+2),and£=dielectric constant ofthescattering particles. Thevalue ofIK12forwatervarieswithtemperature andwavelength. 
 1818-21, November, 1968.  92. Nester, W. 
 BEAM ELLIPSE  SO THE MAIN 
 Researchers also proposed some methods to get high-classiﬁcation accuracy [ 13–15], these methods have high requirements for on features and classiﬁers, so these methods could not applied in other datasets. With the development in neural networks, researchers now focus on processing SAR images with deep neural networks (DNNs) [ 16–18]. Sensors 2019 ,19, 63; doi:10.3390/s19010063 www.mdpi.com/journal/sensors 295. 
 pulse-forming network arerequired. Thebypassdiodeandtheinductance L8connected inparallelwiththethyratron serveto dissipate anychargeremaining inthecapacitance duetotubemismatch.Ifthischargewere allowedtoremain,thepeakvoltageonthenetwork wouldincrease witheachcycleandbuild uptoahighvaluewiththepossibility ofexceeding thepermissible operating voltageofthe thyratron. Themismatch ofthepulse-forming network tothenonlinear impedance ofthetube mightalsocauseaspiketoappearattheleadingedgeofthepulse.Thedespiking circuithelps minimize thisefTect.Thedamping network reducesthetrailingedgeofthepulseandprevents post-pulse oscillations whichcouldintrQduce noiseorfalsetargets. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.42  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 center-fed series feed. Because the bandwidth performance of each is comparable, the  optical-feed criterion is  Bandwidth (%) = bandwidth ( °) (CW)  Table 13.2 summarizes the bandwidth criteria for the various feed networks. 
 16.37.—Subclutter visibility meter.-PAttenuator 7Matching network Toreceiver amplitude byacontrolled amount atacontrolled doppler frequency, so that itimitates amoving target inclutter. The minimum percentage modulation for threshold signal visibility isameasure ofsubclutter visibility. Although the simple modulation scheme shown does not provide anexact duplication ofamoving-target echo, itisbelieved tobe equivalent fortest purposes. 
 This changes the number in the range register toward the value corresponding to  the range of the target. Range readout is accomplished by reading the number in the  register, where, for example, each bit may correspond to a 2-yd range step. FIGURE   9.16  Early- and late-gate range-error-sensing circuit ch09.indd   22 12/15/07   6:07:25 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
  
 31)  Figure 2.23 Additional signal-to-noise  ratio required to achieve a particular  probability of detection, when the  target cross section fluctuates, as com- _5 '--...l.--..1..----1.._--1.._..___.___._-1--..1._..1..-_.i.___--1.._-1-.,....J pared with a non fluctuating target;  0.01 0.05 0.1 0.2 0.3 0.5 0.7 0.8 0.9 0.95 0.99 single hit, n = L (To be used in con- Probability of detection junction with Fig. 2.7 to find (S//\1) 1.) . 30  ro  "O  0 25 u  .E  c  <lJ  E 20 <I.I > e a. 
 460 THE RECEIVING SYSTEM—RADAR RECEIVERS [SEC. 12.8 itisnecessary toprevent earlier stages from becoming overloaded, they can beshunted byanother similar loop. The gain ofthefeedback 100p can beincreased either byusing aplate detector instead ofadiode, orby converting the cathode follower into ad-c amplifier. 
 The moving window in Figure 7.3 a performs a running sum of  n pulses in each range cell,  Si = Si−1 + xi − xi−n (7.5) where Si is the sum at the ith pulse of the last n pulses and xi is the ith pulse. The per - formance12 of this detector for n ≈ 10 is only 0.5 dB worse than the optimal detector  given by Eq. 7.3. 
 61.Pettengill, G.H.:RadarAstronomy, chap.33of"RadarHandbook," M.I.Skolnik(ed.):McGraw­ HillBookCo.,NewYork,1970. 62.Lin,Y.-T.,andA.A.Ksienski: Identification ofComplex Geometrical ShapesbyMeansofLow­ Frequency RadarReturns, TheRadioandElectronic Engineer, vol.46,pp.472-486, October, 1976. 63.Frank,R.L.:Polyphase CodeswithGoodNonperiodic Correlation Properties, IEEETrans.,vol. 
   
 They investigated many of the statistical  problems associated with the noncoherent detection of targets in gaussian noise.  (Note: If the inphase and quadrature components are gaussian distributed, the enve - lope is Rayleigh distributed and the power is exponentially distributed.) Marcum’s  most important result was the generation of curves of probability of detection ( PD) ver- sus signal-to-noise ratio ( S/N) for a detector that sums N envelope-detected samples  (either linear or square-law) under the assumption of equal signal amplitudes. Whereas  for a phased array, the equal amplitude assumption is valid; for a rotating radar, the  returned signal amplitude is modulated by the antenna pattern as the beam sweeps over Chapter 7 7 .1 ch07.indd   1 12/17/07   2:12:45 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 PULSE STAGGERING  IS EMPLOYED  THE EFFECT OF FEEDBACK IS REDUCED 3TAGGERING CAUSES A MODULATION OF THE SIGNAL DOPPLER AT OR NEAR THE MAXIMUM RESPONSE FREQUENCY OF THE CANCELER 4HE AMOUNT OF THIS MODULATION IS PROPORTIONAL TO THE ABSOLUTE TARGET DOPPLER SO THAT  FOR AN AIRCRAFT FLYING AT  6 "  THE CANCELER RESPONSE IS ESSENTIALLY INDEPENDENT OF THE FEEDBACK  EMPLOYED &IGURE  SHOWS A PLOT OF  THE EFFECTS OF FEEDBACK O N A DUAL 
 In the denoising step, an Enhanced Frost ﬁlter, as described in Section 2.1,w i t ha5 ×5 window size was ﬁrst used to mitigate the speckle noise effects. Then, a 9 ×9 low pass ﬁlter was used to smooth the test areas in order to obtain more uniform ﬂow ﬁelds in the optical ﬂow processing step. The remaining steps are grouped in three stages and described in the following subsections. 
 Inverse SAR. Instead of moving a radar relative to a stationary object, it is possible to  generate an image by moving the object relative to a stationary radar Imaging with a station-  ary radar and moving target is called inverse SAR or ronge-doppler imaging. It has been applied  528INTRODUCTION TORADAR SYSTEMS thismodeisthatthescenetobeimagedisobserved overarangeofincidence angleswhich averages thespeckleandmakesasmoother image. 
 34!4% 42!.3-)44%23   ££° MAINTAIN LONG 
 It is the projected area of a metal sphere which would return the same echo signal as the target had the sphere been substituted for the target. Unlike the echo of the sphere, however, which is independent of the viewing angle, the echoes of all but the simplest targets vary significantly with orienta- tion. As such, one must mentally allow the size of this fictitious sphere to vary as the aspect angle of the target changes. 
 A single sinusoidal component of a complex surface is shown with an incoming  radar wave at angle of incidence q. The radar wavelength is l, and the surface- component wavelength is Λ. When the signal travels an extra distance l = 2∆R  between the source and two successive wave crests, the phase difference between  the echoes from successive crests is 360°; so the echo signals all add in phase. 
 Barton: Antenna Pattern Loss Factor for Scanning Radars, Proc. l EEE.  vol. 
 BASED RAIN 
 Tile ovi.:rall effect on lhe  tracker is somewhat analogous to "glint" (Sec. 5.5).  12.3 THE ROUND EARTH .J  In general. 
 Memo. Rept. 5741, May 1986. 
 It is possible to estimate the fo l- lowing standard values:       1) Losses ~ 2*1,75  dB, T/R -Hybrid ~ 6.5  dB, power losses ~ 3  dB, total =  13 dB  2) Integration coherent over 512 pulses, processing losses accounted for to 10dB   3) (POD  > 80%; POF  < 2%)    The minimum receiving power PRmin is: Objekt  σmin/dBm2 σmax/dBm2  car (from the rear)  0 20  truck (from the rear)  0 40  motorbike  -10 10  bicycle  -10 5  person  -10 0  stone  -10 -  Table 13.2  Typical reflection cross -section values for 76 GHz ACC  Radar.   Noise bandwidth  BN 150 MHz   RF losses1 LRF 13 dB  Phase noise (at 100  kHz)  PN <-85dBc/Hz   Noise figure  F 12 dB  Processing gain2 GI 17 dB  Signal -to-Noise ratio3 S/N 8 dB  Thermal noise  kTBN -92,5 dBm   Antenna gain  GT, GR 35 dB  Range  R 150 m  Reflection cross -section  σ 1 m2  Table 13.3  Typical values of a p ower budget for a 76 GHz ACC sensor.  . 
 An IMM filter can be used to systematically transition  between these different phases of flight, providing a single filter output. Figure 7.31  shows the model probabilities for such an IMM filter application. FIGURE 7.31  Model probabilities resulting from the application of an IMM filter to a ballistic   missile tracking problem: ( a) probability that target motion is “boost phase,” ( b) probability that target  motion is “exo-atmospheric” flight, ( c) probability that target motion is “endo-atmospheric” re-entry. 
 How- ever, most of the basic principles and limitations of monopulse apply for all ap- plications. A more general coverage is found in Refs. 3 and 4. 
 J. Smith: Radar Echoing Areas of Birds. Royal Radar Estahlishmellt  /\fe111ora11d11m no. 
   NO   PP n   -AY   ' 2 !RMSTRONG AND - !XELBANK  h$ESCRIPTION OF THE LONG 
 The next link in our chain is the aerial—the aerial at  the transmitting end and the aerial at the receiving end.  For an appreciation of radar technique it is necessary  to change our normal conception of the propagation of  electromagnetic waves. In a broadcast receiver we use  an aerial of an indefinite length and a ‘lead-in’ of any  reasonable proportions to link receiver to aerial, without  worrying unduly about the electrical constants of the  aerial-earth circuit. 
 After the machine has run foranhour or longer, the moisture isusually driven offand the voltage returns to normal. During this drying-out period the carbon disks are often. sm.145] VOLTAGE REGULATORS 569 burned because, asthe film ofmoisture isgradually reduced, itmay break down atone particular point ontheface ofthedisk and the high current-density atthat point may besufficient toburn the disk. 
 The fixed  targets with unchanging amplitudes from pulse to pulse are canceled on subtraction.  flowcvcr, the amplitudes of the moving-target echoes arc not constant from pulse lo pulse, and  subtraction results in an uncanceled residue. The output of the subtraction circuit is bipolar  Bipolar video .--~~--. 
 Union , 1943, pp. 452–460. 49. 
 xx     Contents   13.3 Empirical Behavior of Sea Clutter  ...........................  13.6  Dependence on Wind Speed, Grazing Angle,  and Frequency  ................................................  13.8  The Spectrum of Sea Clutter  .............................. 
 It has been  found that the use of the four-lobed antenna pattern in addition to the conventional  monopulse beams (sum, difference in azimuth, and elevation) can improve the estima - tion of the target DoA in presence of a jammer. Joint Adaptive Jammer and Clutter Cancellation.  Clutter, always present in  a radar, negatively affects the performance of the adaptive jammer cancellation;  therefore, means have to be adopted to effectively contrast the contemporaneous  presence of clutter and jammer. 
 99. Sheleg, B.: Butler Submatrix Feed Systems for Antenna Arrays, IEEE Trans., vol. AP-21, pp. 
 II. A signiﬁcant change was to reduce the aperture of the re ﬂector (mirror) from 36 inch to 28 inch, in order to be able to mount the scanner in the nose of the Wellington aircraft[2]. This would have given an azimuth beamwidth of about 10 °. 
 TO 
 ING THE RESULTING DATA BURDEN TO SHARE THE COMMUNICATIONS LINK WITH THE TWO OTHER HIGH DATA 
 SIVE MEASUREMENTS HAVE BEEN MADE FROM TRUCKS AND HELICOPTERS BY THE 5NIVERSITY OF +ANSAS    GROUPS IN THE .ETHERLANDS   AND SEVERAL GROUPS IN &RANCE   4HESE  MEASUREMENTS CONCENTRATED ESPECIALLY ON VEGETATION  WITH THE +ANSAS MEASUREMENTS ALSO INCLUDING SOME WORK ON SNOW AND EXTENSIVE WORK ON SEA ICE -OST OF THESE MEA 
 RECEIVE SITE  AVOIDING THE COST AND COMPLEXITY OF ACQUIRING SUITABLE LAND  DUPLICATING MANY FACILITIES AND SYNCHRONIZING TWO WIDELY SEPARATED SITES 3ECOND  THE ABILITY TO GATE THE ECHOES IN TIME MEANS THAT THE ONLY CLUTTER POWER THAT IMPACTS ON THE RANGE FOOTPRINT SPANNED BY A PULSE IS CLUTTER ORIGINATING IN THAT FOOTPRINT 4HIS RELAXES THE WAVEFORM GENERATOR DYNAMIC RANGE REQUIREMENTS SOMEWHAT  ESPECIALLY WHEN PHENOMENA SUCH AS AURORAL CLUTTER MAY  CAUSE PROBLEMS  THOUGH TO ACHIEVE THE SAME PROBABILITY OF DETECTION  PEAK POWER MUST INCREASE TO MAINTAIN EQUIVALENT AVERAGE POWER 4HIRD  AS A CONSEQUENCE OF REDUCED DYNAMIC RANGE REQUIREMENTS AND ASSUMING FOR THE MOMENT THAT STRICT SPECTRAL EMISSION CONTROLS ARE NOT AN ISSUE  MORE EFFICIENT AMPLIFIERS CAN BE USED  AS DISCUSSED IN THE FOLLOWING SECTION &OURTH  PULSE WAVEFORMS MAY BE LESS SUSCEPTIBLE TO SOME FORMS OF JAMMING.   (& /6%2 
 MITTED TO TRANSMIT ANY WAVEFORM AT  '(Z  PROVIDING THE SPECTRUM LIMITATIONS ON  MARINE RADAR ARE NOT EXCEEDED 4HE LIMITS HAVE BEEN AGREED WITHIN THE )NTERNATIONAL  4ELECOMMUNICATION 5NION )45   A 5NITED .ATIONS AGENCY BASED IN 'ENEVA 4HIS CHAPTER CONCENTRATES ON THE REQUIREMENTS AND DESIGN OF RADARS FOR COMMER 
 CM WAVELENGTH RADIO WAVE WAS BEAMED AT THE SURFACE BY THE TELEMETRY ANTENNA  AND BOTH THE DIRECT AND REFLECTED SIGNALS WERE RECORDED BY %ARTH 
   2%&,%#4/2 !.4%..!3   £Ó°£Î 2EFLECTOR ANTENNA GAIN LOSS DUE TO SURFACE ROUGHNESS HAS BEEN DISCUSSED BY *OHN  2UZE  USING A STATISTICAL POINT OF VIEW 4HE LOSS OF GAIN DUE TO SMALL ROUGHNESS ERRORS  IS APPROXIMATELY  ' ' y 
 As will be seen, this effect can result in very considerable increase or decrease of the radar detection range compared with the free-space range. In this chapter, the basic ideas of pattern-propagation-factor calculation and some typical multipath-interference results will be presented. Additional details are given in Ref. 
 38. F. T. 
 A typical performance in sidelobe jamming when the jamming level varies by 20 dB per pulse is shown in Fig. 8.17. By employing a second test to identify the presence of narrow-pulse interference, a detection performance approximately halfway between the limit- ing and nonlimiting ratio detectors can be obtained. 
 Hayne, and C. L. Purdy, “NASA radar altimeter for the  TOPEX/Poseidon project,” Proceedings of the IEEE , vol. 
 WL1630.22, AD 51858, June 1970. (Not readily available.) 16. Brennan, L. 
 60, pp. 735-736, June,  1972.  88. 
 Domville reports109 that at low 9/ no significant variation in aB° was observed for rural and forest terrain when measured at a small out-of-plane angle, <)> = 165°. Also at low 9, no significant variation between horizontal, vertical, and crossed polarizations was observed for rural and forest terrain. For semidesert, cr^0 was measured110 at -40 dB for both horizontal and ver- tical polarization at 9, < ~ 1° and for all 9S > ~ 1°. 
 BAND 3!2 ! SIMULATION EXPERIMENT SHOWED THAT ONE  CAN ESTIMATE SOIL MOISTURE WITHIN  FOR  OF THE PIXELS IN AN IMAGE -OREOVER   IT SHOWED THAT RESOLUTIONS BETWEEN  AND  M WERE SUPERIOR TO FINER RESOLUTIONS  &)'52%     -EASURED SCATTERING VARIATION OF A FOREST PARCEL OF OLD BEECH  TREES .OTE USE OF  F  WITH AN ARBITRARY REFERENCE  INSTEAD OF  R  FOR THE ORDINATE  AFTER $ ( (OEKMAN  . 
 McGraw-Hill  Rook Co.. New York, 1970.  36. 
 The multipactor has the disadvantage of being complex, and it  offers no protection if the power is turned off.  With fast-rise-time, high-power RF sources, the receiver protector may be required to  self-limit in less than one nanosecond. This can be achieved with fast-acting PN (varactor)  diodes. 
 This5“ light isyellowish and does notaffect4“ the persistence oftheradar signals3“ onthePPI. Inaddition there isa2“ color contrast between itand the1“echoes. By rotating the antenna0“oftheType 13until this’ ‘azicator” line cuts thecenter ofthesignal on the PPI, the Type 13can becor-Ground echoes rectly enough pointed toclisplay the IkG. 
 223-224. 239 Bootlace antenna. 316 Boxcargenerator. 
 The absence of the fre- quency in this expression implies that the noise is white—that the spectrum is uniform and extends to infinitely high frequency. But this also implies infinite en- ergy, an obvious impossibility, indicating that Eq. (2.29) is an approximation. 
 13.5. Electromechanical Repeaters.—Two types ofelectromechanical devices are used torepeat the motion ofarotating shaft ataremote point. },;1 1 eI I 0I A.cline~Repeater shaff FIG. 
 By applying the convolution theorem to Eq. ( 11.6), the Fourier transform of the  output S0(J) is equal to Sg(f )S*(J), or  j2nf I S(J) 12  So(J)=· 1N:C/Y12·· (11.10)  This is a transform of an odd function.  The gating signal and the matched filter are related to one another. 
 CESSING  SEE &IGURE    OR BY USING A FORWARD 
 AI) Aircraft Radio Laboratory, 15 Airways, 574 Alternator, airborne, direct-driven, 557- 561 wave shape of,557 aircraft, alternatives todirect-driven, 56JI inductor, performance of,557 voltage regulators for (see Voltage regulators) (See also Motor-alternator) Altimeter, radio, 143-147 Altitude signal, 88 Alvarez, L.W., 291 A.M.E.S.,Type 7,186 Type 13,190 Amplified back-bias, 459 Amplifier, gated, 50s510 i-f,8 design of,442-449 double-tuned, 446 single-tuned, 445Amplifier, negative feedback, 492 phase-splitting, 495 squaring, 497 two-channel, for MTI, 672–675 video, 8,45&453 cutoff frequency of,451 rise time of,450 Amplitude factor, 557 Amplitude modulation (see Modulation, amplitude) AN/APA-15, 306 AN/APG-1, 202 AN/APG-2, 202 AN/APG-15, 206 AN/APQ-7 scanner, 291-295 AN/APs-3, 199 AN/APs-4, 199 AN/APs-6, 203 spiral scanner, 290 AN/AP&lO, detailed design of, 61& 625 detailed specifications of,619 general design of,614 performance of,622 scanner, 288 units of,618 AN/APs-15, 199 Angle indices, 514-518 fixed electronic, 514 movable electronic, 516 AN/MPN-l (see GCA) Antenna, beamwidth of(see Beamwidth) cosecant-squared, 23-27 end-fire, 277 gain of(see Gain, ofantenna) mechanical construction of,279-280 nonscanning, 277–279 paraboloid, 272–274 polyrod, 278 forradar relay, 713-719 receiving cross section of(nee Cross section, effective receiving) 737. 738 RADAR SYSTEM ENGINEERING Antenna, rolled parallel-plate scanning, 304 Schwartzschild, 29$298 ofSCIheight finder, 298-302 stabilization of(see Stabilization; Sta. bilizer) Yagi, 277 Antenna equation, 271-272 Antemafeedj 272–274 Antenna iilterfor radar relay, 720 Antenna mount, 271 Antenna pattern for airborne ground- mapping, 23 Antenna temperature, 32 Anticlutter circuits, 460 Antijamming, 457–460 AN/TPG-1, 210, 211 AN/TP$lO, 191 antenna mount of,286 Array, corrugated coaxial line, 303 ofpolyrod radiators, 303 A-and-R-scope, 166 ASB, 197 A-scope, 164 design of,524-528 ASD, 199 ASD-1, 199 ASE, 196 ASG, 199 ASH, 199 Aspect function, 88 ASV Mark II,196 ATR switch, 7,407411 ATR tube, 407 Attenuation, byfog orcloud, 60,62 ofmicrowaves inatmosphere, 58 byrain, 61 bywater droplets, 60 inwaveguide (see Waveguide, attenua. 
 Siegel, “Bistatic radars and forward scattering,” in Proc. Nat. Conf. 
 NATED  BUT NOT  &IGURE  SHOWS THE EFFECT OF 34# AGAINST BATS AND INSECTS o  o  $AYTIME BIRD RETURNS AND NIGHTTIME BAT AND INSECT RETURNS CAN OFTEN BE SEEN IN REAL TIMETHE EXTENT DEPENDS ON THE  WEATHER AND TIME OF YEARON THE .%82!$ 732 
 Geophys. ANGEO 2005 ,23, 707–721. [ CrossRef ] 2. 
 - Ê"Ê  1// 
 The jagged curve in the transi - tion region is due to the parameter selection process; in radar operation, the frequency  would be selected to minimize transition effects. The frequency, radiation angle, and  noise power per hertz that go with this site and look direction are also plotted. FIGURE 20.30  Radar performance-controlling variables plotted as a function of  range for January, 1800 UTC, SSN 50. 
 1970.  I?. Sinsky. 
 The values change by about an order of magnitude, for a change of A. from 1 to 3 cm. The data presented here also shows that attenuation in water clouds increases with decreasing tem- perature. 
 RATE CAPABILITY EMERGED AS THE TOUGHEST REQUIREMENT ON THE ENTIRE SYSTEM 2AW 3!2 DATA RATE IS PROPORTIONAL TO THE IMAGE QUALITY FACTOR   SWATH WIDTH  SPACE 
 0.1 1.0 10 100  Frequency, gigacycles  Figure 2.28 Theoretical (one-way) attenuation of RF transmission lines. Waveguide sizes are inches and  are the inside dimensions. (Data .from Armed Services Index of R.F. 
 The parameters (S/ N)1 and 11£;(11) are substituted into the radar equation (2.33)  along with <Ta,.  The integration-improvement raclor in Fig. 2.24 is in some cases greater than 11, or in  other words, the integration efficiency factor E1(n) > 1. 
 Antennas Propag ., pp. 466–469, 1990. 30. 
 Peck and G. W. Goodman, Jr., “Agile radar beams,” C4ISR Journal , pp. 
   &H      3PECIFIC DIFFERENTIAL PHASE +DP   D &DP   DR      #O 
 If the radar were to integrate additional noise samples along with the wanted  signal-to-noise pulses, the added noise results in a degradation called the collapsing loss. It can  occur in displays which collapse the range information, such as the C-scope which displays  elevation vs. azimuth angle. 
 The reflector was fabricated of three triangular plywood panels, metallized to enhance their surface reflectivities. The aperture exposed to the ra- dar was therefore an equilateral triangle, as shown in Fig. 11.13. 
 Movable Electronic AngleIndices.-The methods ofproducing fixed electronic angle indices can beextended toprovide movable ones. This can most easily bedone, with thesynchro method ofFig. 13.34, bvUsiw. 
 They employ coherent processing to reject main-beam clutter, enhance tar- get detection, and aid in target discrimination or classification. Applications. PD is applied principally to radar systems requiring the detection of moving targets in a severe clutter environment. 
 I. Skolnik (ed.).  McGraw-Hill Book Company, New York. 
 When a radar is performing volume search and jamming power enters from a particular direction via the sidelobes, the maximum range can be written -4 _P»v± « R/Bj * max - gs flElN~0PjGj U'°; where gs = sidelobe level relative to main beam (number less than unity) Rj = jammer range Bj = jammer bandwidth Pj = jammer power Gj = jammer antenna gain and EIN0 is the ratio of signal energy to noise power per unit bandwidth nec- essary for reliable detection. The parameter of importance is the average power. The antenna sidelobes are also important. 
 The receiver is usually of the superheterodyne type. The first stage might be a low-noise  RF amplifier, such as a parametric amplifier or a low-noise transistor. However, it is not  always desirable to employ a low-noise first stage in radar. 
 Braun, i: JI.: Radiation Characteristics or the Spherical Luneburg Lens, I RE Trans .. vol. AP-4. 
 W.: A Broadband Microwave Noise Source, Bell System Tech. J., vol. 28, pp. 
 At near vertical incidence (4> ~ 90°) the radar echo is relatively large.  This is called the quasi-specular region and seems to be the result of specular scatter from  facetlike surfaces oriented perpendicular to the direction of the radar. At the other extreme,  when the grazing angles are. 
 Consequently, a wide servo bandwidth which reduces lag errors allows the noise to cause erroneous motions of the tracking system. Therefore, for best overall performance it is necessary to limit the servo bandwidth to the minimum necessary to maintain a reasonably small tracking-lag error. There is an optimum bandwidth that minimizes the rms of the total erroneous outputs includ- ing both tracking lag and random noise, depending upon the target, its trajectory, and other radar parameters. 
 TRACKING SYSTEM &URTHERMORE  THE PATHS ARE  ALMOST EQUAL  AND IN MOST CASES  THEY CANNOT BE RESOLVED BY HIGH 
 ING ON SEA STATE  ,AND #LUTTER  -APPING OF SKYWAVE BACKSCATTER FROM TERRESTRIAL LAND  SURFACES   IS OF INTEREST FOR TWO MAIN REASONS &IRST  A LOCALIZED AREA OF ENHANCED BACKSCATTER  SUCH AS A CITY IN THE CENTRAL PLAINS OF THE 53 OR A MOUNTAIN RISING FROM A TROPICAL &)'52%  -ONOSTATIC 2#3 OF THE & 
 Fried, W. R.: New Developments in Radar and Radio Sensors for Aircraft Navigation, IEEE Trans.,  vol. AES-10. 
 Painted rather than bright surfaces areworth while, however. Fins arehelpful inincreasing effective area, especially with natural con- vection, though not inproportion toactual surface. Ifthe forced con- vection isnotalong thefins they donothelp atall,because theincreased area iscompensated byimpediment toairflow. 
 Denenberg, Serafm, and Peach42 give the following ex- pression for the variance of mean-frequency estimates of the doppler spectrum var(/) = -J- ff2S2(f + f }df (23.38) P2T0J This is an interesting result, showing that the variance of the estimate/is a func- tion only of the shape of the doppler spectrum and the integration time T0. If the spectrum has a gaussian shape, with variance oy2, Eq. (23.38) becomes var(/) = ^ (23.39)4V^r0 Noting that var(v) = (X/2)2 var (/), we can write var (v) = —— (23.40)8V^r0 If we multiply numerator and denominator by crv, Eq. 
 With thedipole spacing actually used, this occurs when the inside width aoftheguide is1.200 in. Let usassume that the energy ispropagated inthe wave- guide from left toright. Then, asthe guide isnarrowed to0,660 in., the beam moves 30° toward the left, that is,inthe backfire direction. 
 The delay between  the true echo and the false echo can be lengthened or shortened to such an extent that the . 552 INTRODUCTION TO RADAR SYSTEMS  range servo limits in the radar receiver are exceeded, or else the repeater can be turned off,  leaving the tracker without a target and forcing it to revert to the search mode.  CW radars sometimes employ a tunable filter called a velocity gate to track the dopplcr  frequency shift. 
 Consequently, elevation and azimuth information is sequential  and must be separated for use in each tracking coordinate. Conopulse provides the  monopulse advantage of avoiding errors caused by amplitude scintillation, and it  requires only two receivers. However, it has the disadvantage of lower angle data  rates and the mechanical complexity of providing and coupling to a pair of rotating  antenna feedhorns. 
 --" Ê * 
 AMPLITUDE INTERNAL WAVES OBSERVED OFF THE NORTHWEST COAST  OF 3UMATRA v * 'EOPHYS 2ES  VOL   PP n     7 !LPERS AND ) (ENNINGS  h! THEORY OF THE IMAGING MECHANISM OF UNDERWATER BOTTOM TOPOGRAPHY  BY REAL AND SYNTHETIC APERTURE RADAR v * 'EOPHYS 2ES  VOL  PP n    7 'ARRETT  h0HYSICOCHEMICAL EFFECTS OF ORGANIC FILMS AT THE SEA SURFACE AND THEIR ROLE IN THE  INTERPRETATION OF REMOTELY SENSED IMAGERY v IN  /.2, 7ORKSHOP 0ROC2OLE OF 3URFACTANT &ILMS  ON THE )NTERFACIAL 0ROPERTIES OF THE 3EA 3URFACE  & , (ERR AND * 7ILLIAMS EDS   .OVEMBER      PP n  ( (UHNERFUSS  7 !LPERS  7 $ 'ARRETT  0 ! ,ANGE  AND 3 3TOLTE  h!TTENUATION OF CAPILLARY  AND GRAVITY WAVES AT SEA BY MONOMOLECULAR ORGANIC SURFACE FILMS v  * 'EOPHYS 2ES  VOL     PP n    * # 3COTT  h3URFACE FILMS IN OCEANOGRAPHY v IN  /.2, 7ORKSHOP 0ROC2OLE OF 3URFACTANT &ILMS  ON THE )NTERFACIAL 0ROPERTIES OF THE 3EA 3URFACE  & , (ERR AND * 7ILLIAMS EDS   .OVEMBER     PP n  . 7 'UINARD  h2ADAR DETECTION OF OIL SPILLS v PRESENTED AT *OINT #ONF 3ENSING OF %NVIRONMENTAL  0OLLUTANTS  !)!! 0AP n  0ALO !LTO  #!  .OVEMBER n    ( (ÓHNERFUSS  7 !LPERS  ! #ROSS  7 $ 'ARRETT  7 # +ELLER  0 ! ,ANGE  7 * 0LANT     &   3CHLUDE  AND $ , 3CHULER  h4HE MODIFICATION OF 8 AND , BAND RADAR SIGNALS BY MONOMOLECULAR  SEA SLICKS v * 'EOPHYS 2ES  VOL   PP n    # 3 #OX AND 7 ( -UNK  h3TATISTICS OF THE SEA SURFACE DERIVED FROM SUN GLITTER v  * -AR 2ES   VOL   PP n    7 !LPERS AND ( (ÓHNERFUSS  h2ADAR SIGNATURES OF OIL FILMS FLOATING ON THE SEA SURFACE AND THE  -ARANGONI EFFECT v * 'EOPHYS 2ES  VOL   PP n  !PRIL     ( -ASUKO AND ( )NOMATA  h/BSERVATIONS OF ARTIFICIAL SLICKS BY 8 AND +A BAND AIRBORNE SCAT 
 In order to maintain good bearing estimates in the dead-ahead position for homing onto a target, the actualAirborne Maritime Surveillance Radar, Volume 1 3-15. switch-over took place at 15 °to port of the dead-ahead position, so that the starboard scanner covered 195 °. The main conclusions of the early CCDU trials were that detection performance compared well with that in a Wellington, previously reported in [ 13], with an important advantage of having a full 360 °azimuth coverage. 
 PLANE PLOT OF FAR 
 LAG 
 Since the transmitter and the receiver local oscillator are frequency- modulated in synchronism, the deviation of the IF difference signal is dependent on the range delay. Droop. Although it does not cause new spectral sidebands and therefore was not included in Table 17.5, pulse droop on the transmitter modulator pulse is also of interest. 
 RATE CONDITIONS  ARE LESS THAN PER 
 FREQUENCY  DEVICES REQUIRE SHALLOW  NARROW  HIGH 
 Range information is also extracted from the sum channel. A duplexer is included  in the sum arm for the protection of the receiver. The output of the phase-sensitive detector is  160INTRODUCTION TORADAR SYSTEMS 5.4MONOPULSETRACKING RADAR1.2.13-18 Theconical-scan andsequential-Iobing tracking radarsrequireaminimum numberofpulses inordertoextracttheangle-error signal.Inthetimeintervalduringwhichameasurement is madewitheithersequential lobingorconicalscan,thetrainofechopulsesmustcontainno amplitude-modulation components otherthanthemodulation produced by"scanning. 
 The angle corresponding to the minimum reflection coefficient is called Brew-  ster's angle.  The different reflection coefficients with the two polarizations result in different coverage  patterns. The nulls are not as deep with vertical polarization, nor are the lobe maxima as great. 
 The beat frequency obtained bymixing asmall part ofthe transmitter power with local-oscillator power isamplified bytwo i-fstages and then applied tothediscriminator. The video pulses from the disitiminator undergo one stage ofamplifica- tion before reaching thecontrol tube, Vb(Fig. 12.23). 
 From the 1970s, the range of  applications has been expanding steadily, and now includes those given in Table 21.1.  Purpose-built equipment for each of these applications has been being developed, and  the user now has a better choice of equipment and techniques. GPR has advanced rapidly as a result of a variety of applications, but as the require - ments have become more demanding, so the equipment, techniques, and data process - ing methods have been developed and refined. 
 SIGHT VELOCITY )F THE TARGET MOTION IS IN A  STRAIGHT LINE AT CONSTANT SPEED  THE TARGET IMAGE WILL BE DISPLACED IN CROSSRANGE BY   R66 2 6DISPL,/3 ,/3  7    WHERE 7 IS  THE APPARENT ROTATION RATE OF THE SCENE RELATIVE TO THE RADAR AND 6,/3 IS THE TARGET  VELOCITY COMPONENT ALONG THE RADAR LINE 
 239-244.  67. Waite, A. 
 Bayma, R. W., and P. A. 
 Eng., 1974,  pp. 213–232.  6. 
 OFF NOISE 2EALIZING MAXIMUM PERFORMANCE REQUIRES CAREFUL ATTENTION TO DESIGN DETAILS $IRECT $IGITAL $OWNCONVERSION  )F THE DESIGNER HAS SOME FLEXIBILITY IN EITHER  THE )& CENTER FREQUENCY OR !$# SAMPLE RATE  A SIMPLIFIED $$# ARCHITECTURE  DIRECT DIGITAL DOWNCONVERSION  CAN BE CONSIDERED   )F THE !$# SAMPLE RATE IS FOUR TIMES  THE CENTER OF THE )& BAND  THEN THE SAMPLING PROCESS CAN ALSO SHIFT THE SPECTRUM TO BASEBAND  AND THE .#/ AND ASSOCIATED MULTIPLIERS OF THE GENERAL $$# ARE NOT NEEDED )N GENERAL  DIRECT CONVERSION TO BASEBAND IS A SIMPLE AND COST 
 Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 5.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 Each bar consists of multiple beam positions of a few tens of milliseconds each, which  are computed on the fly to optimally cover the selected volume. Each beam cycle, in turn,  may contain one or more radar modes or submodes, such as those contained in Tables 5.1  or 5.2 and depicted in the lowest line of Figure 5.6. 
 STATE TRAN 
 Synthetic Aperture Radar (SAR) Techniques and Applications    •   Fabio Bovenga Synthetic Aperture  Radar (SAR)  Techniques and  Applications Printed Edition of the Special Issue Published in Sensors www.mdpi.com/journal/sensorsFabio BovengaEdited by. Synthetic Aperture Radar (SAR) T echniques and Applications. 
 +1/" - ! REVIEW OF THE BASIC EQUATIONS OF 3!2 FOLLOWS L 2ANGE RESOLUTION   CR   C" C   SPEED OF LIGHT  "   PULSE BANDWIDTH  L #ROSSRANGE RESOLUTION   CCR   K  $P  K   WAVELENGTH  $P   ANGLE SUBTENDED BY SYNTHETIC APERTURE  L 0HYSICAL BEAMWIDTH   K  $ $   ANTENNA DIAMETER &)'52%  3!2 IMAGE OF THE 7ASHINGTON -ONUMENT 4HE 3!2 IMAGE SHOWS THE SIDE OF THE -ONUMENT  THAT IS ON THE OPPOSITE SIDE OF THE SHADOW  WHICH MAY APPEAR COUNTERINTUITIVE TO A HUMAN OBSERVER  #OURTESY  OF 'ENERAL $YNAMICS  9PSILANTI  -ICHIGAN  . £Ç°ÓÓ  2!$!2 (!.$"//+  L #ROSSRANGE RESOLUTION FOR STRIPMAP 3!2   DL QL LCRyy    $ $$    L )MAGE #OLLECTION 4IME T!   K26CCRCOSPSQ  L 02& F2   02& q 6$ 6   PLATFORM VELOCITY  L 02& LIMITS FOR UNAMBIGUOUS RANGE  F2   C2   6 $FC 22a       &OR STRIPMAP 3!2    3C 6 DYCRa COS   L 3IGNAL 
 TION OF THE FIRST KIND OF ORDER  %QUATIONS  THROUGH  ALL REDUCE TO THE VALUE  LISTED IN 4ABLE  FOR NORMAL INCIDENCE &OR FURTHER COMPARISON  THE 0/ PATTERNS OF TWO SQUARE PLATES AND A CIRCULAR DISK ARE PLOTTED IN &IGURE . 
 Trew, “SiC and GaN transistors—Is there one winner for microwave power applications?”  Proceedings of the IEEE , vol. 90, no. 6, pp. 
 5  Signal Timing  ................................ ................................ ................................ 
 112. U. Nickel, “Overview of generalized monopulse estimation,” IEEE AES Magazine , vol. 
 FED PARABOLIC REFLECTORS ARE OFTEN USED TO MITIGATE FEED BLOCKAGE (OWEVER   REFLECTOR SHAPING CAN ALSO BE USED TO MITIGATE BLOCKAGE AND IS SOMETIMES APPLIED TO REDIRECT THE REFLECTED ENERGY AWAY FROM THE FEED  AS SHOWN IN &IGURE  &IGURE  ILLUSTRATES HOW SHAPING CAN BE APPLIED TO VIRTUALLY ELIMINATE BLOCKAGE EVEN THOUGH THE FEED APPEARS TO BE WITHIN THE &/6 OF THE REFLECTOR 4HE !32 
 M LONG .OTE THAT THE SPACECRAFT HAD TO  BE YAW 
 For this system, if the receiving-transmission-line noise temperature is repre- sented by Tr and its loss factor is Lr (=1/G2) and if the receiver effective input noise temperature is Te, Eq. (2.33) becomes T5 = Ta + TV + LrTe (2.34) It now remains to discuss evaluation of T0, Tr, Lr, and Te. Antenna Noise Temperature. 
 One of the earlier 3D radar techniques that has found application for the air surveillance mission is frequency scanning. Frequency-scanned arrays utilize the frequency-dependent phase characteristics of a length of transmission line, usually waveguide, to scan a pencil beam.16 The waveguide is folded into a serpentine configuration on the side (or sides) or back of the array to provide output taps at the locations of the closely spaced antenna elements. A controlled change of transmit/receive RF frequency produces a dif- ferent phase gradient across the aperture, electronically steering the beam to the desired elevation angle. 
 MODULATION DISTORTION OF IN 
 KM RESOLUTION )N ORDER TO SUPPORT  
 [ CrossRef ] 3. Soumekh, M. Synthetic Aperture Radar Signal Processing ; Wiley: New York, NY, USA, 1999. 
 MANCE )N PRACTICE  THE MAXIMUM GATE WIDTH CAN BE FOUND TO APPROACH APPROXIMATELY  §M   §M  OR  §M FOR 3 BAND  8 BAND  OR + A BAND FREQUENCIES  RESPECTIVELY 7ITH A LIMITATION ON MAXIMUM GATE WIDTH  ADDITIONAL CURRENT AND HENCE POWER  CAPABILITY CAN ONLY BE ACHIEVED BY COMBINING MULTIPLE GATE ELECTRODES IN PARALLEL 'ATE ELECTRODES  OR  FINGERS AS THEY ARE OFTEN REFERRED TO  ARE GENERALLY GROUPED IN LOGICALLY  CONVENIENT SUBSTRUCTURES CELLS  THAT ARE STEPPED AND REPEATED TO FORM A SYMMETRIC COR 
 Dewey, R.: Corrugated Waveguide Frequency Scanning Aerials, Proceedings International Confer­ ence on Radar-Present and F11t11re, Oct. 23-25, 1973, IEE Conference Publication no. 105. 
 Substituting  Eq. (2.31) into (2.32} gives  4 P,GAeanE;(n)  Rmax = (411:)2kT0BnFn(S/N)1 (2.33)  The value of (S/N)1 is found from Fig. 2.7 as before, and nE;(n) is found from Fig. 
 It is claimed14 to be preferred for tubes in the  power range from 1 to 20 k W, as for lightweight airborne radar or as drivers for high-power  tubes. The ring-loop circuit is not bothered by the backward-wave oscillations of the ordinary  helix or the "rabbit ear" oscillations which can appear in coupled-cavity circuits.  The I~elix tlas heen operated at high average power by passing cooling fluid through a  lielix constructed of copper tubing.43 The bandwidth of this type of fluid-cooled helix TWT  can be alrnost an octave, arid it is capable of several tens of kilowatts average power at L band  with ;\ duty cycle suitable for radar applications. 
 The patterns are not symmetrical, especially at the higher frequency. Note that the RCS can exceed 1 mi (64.1 dBsm). An empirical formula for the RCS of a naval ship is a = 52/1/2D3/2 (11-4) where/is the radar frequency in megahertz and D is the full-load displacement of the vessel in kilo tons.2d'21 The relationship is based on measurements of several ships at low grazing angles and represents the average of the median RCS in the port and starboard bow, and quarter aspects, but excluding the broadside peaks. 
 The combined temperature of  cosmic noise and atmospheric noise [T, + (L,, - l)T,,] is called the space temperature, the  hriglttrress temperature, or the artterzrta temperature of an ideal antenna. The RF losses L,[  indicated in the figure are meant to include the antenna, radome, and duplexer losses, as well  as transmission-line loss. The effective noise temperature of the receiver is denoted T, . 
 ISTICS AND DEVICES $* ,$+ !# -$(* %( !% 0&&        
 CALLED THERMAL NOISE FROM AN IDEAL OHMIC CONDUC 
 ch06.indd   10 12/17/07   2:03:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 RESOLUTION OCEAN TOPOGRAPHY TO OCEAN TIDES v IN  2EPORT OF THE  (IGH 
 Thiz: is called the  syrti~lt nrodr. The signal processor must be modified to account for the averagc doppler fre-  quency riot being zero. Recorders and displays must beldesigned to account for lh!. 
 Since the information ontarget position isnormally transmitted to the antiaircraft computer bymeans ofsynchros oraccurate potentiom- eters (Sec. 13.4), itisnecessary toprovide asupplementary method of displaying target position thenable thesettobeused forground control. This was first done bymeans ofthe 180° plotting board shown inusein Fig. 
 253–262, 1998.  5. J. 
 BAND  CM  DUAL 
 If saturations occur, spurious signals that degrade performance may be gener - ated. For example, if main-beam clutter saturates, spurious frequencies can appear  in the doppler passband normally clear of main-beam clutter, and this may generate  false-target reports. An automatic gain control (AGC) function is often employed to  prevent saturations on either main-beam clutter in search or the target in Single-Target  Track mode. 
 Appl. Phys., vol. 17, pp. 
 2. A fault-tolerant architecture has led to a system availability of near unity. With a module MTBF of 100,000 h, the maintenance for failed modules can be neglected for nearly 2 years before the transmitter power output degrades by 1 dB. 
 89. Y . Hisaki, “Nonlinear inversion of the integral equation to estimate ocean wave spectra from HF  radar,” Radio Science, vol. 
 in the IF portion of the receiver were A, cos (L),~[, the difference signal woirld be either  A, cos WIFt or -Ad cos WtFC (As > 0, Ad > O), depend~ng on which side of center is the target.  Since -Ad cos qFt = Ad cos wF(t + n), the sign of the difference signal may be measured by  determining whether the difference signal is in phase with the sum or 180" out of phase.  Although a phase comparison is a part of the amplitude-comparison-monopulse radar,  the angular-error signal is basically derived by comparing the echo amplitudes from simulta-  neous offset beams. 
 Choose 53 dBW for Pav, 20 dB for Gt, 30 dB  for Gr, 0 dBs for T, 20 dBsm for RCS, and 6 dB for Fp. Substituting in Eq. 20.2,  SNR dB = + + + + + + − − − − = 532030230 20 6 33260 182 41 ( )   Figure 20.31 shows the performance indicated with these assumptions for all ranges. 
 April. 1973.  19 llill. 
 Kramer and G. Lavas, “Radar System with Target Illumination by Different Waveforms,” U.S.  Patent 3866219, 2/11/1975. 
 ING TWO LESSER POWER AMPLIFIERS TOGETHER TO ACHIEVE THE SAME PERFORMANCE 4HESE REPRESENT COST  CAPABILITY  AND AVAILABILITY TRADES THAT MIGHT BE EXERCISED BY THE 42 MODULE ARCHITECT -ICROWAVE -ONOLITHIC )NTEGRATED #IRCUITS --)#S   $URING THE S  IT  WAS THE REDUCTION 
 This wide variation in sensitivity would have made it more dif ﬁcult for the operator to control the gain when tracking a target through sea returns at short ranges. The scanner rotated at a ﬁxed speed of 60 rpm. It was not stabilised against pitch or roll of the aircraft, nor could the tilt be adjusted. 
 The characteristic  feature of a linear beam tube is that the electrons emitted from the cathode are formed into a  long cylindrical beam which receives the full potential energy of the electric field before the  beam enters the RF interaction region. Transit-time effects, which limit the operation of  conventional grid-controlled tubes at the higher frequencies, are used to good advantage in the  klystron. As the electron beam of the klystron passes the input resonant cavity, the velocity of  the electrons is modulated by the input signal. 
 The  Figure 7.15 Stepped parabolic reflector.  RADAR ANTENNAS 245 diameter) isreduced to80percent ofitsmaximum valuewhenthebeamisscanned ± 3 beamwidths offaxis.AparaboloidwithflD= 0.50canbescanned ±6.5beamswidths offaxis beforethegainisreducedto80percentofmaximum (Ref.1,p.488).Theantenna impedance alsochanges withachangeillfeedposition. Hencescanning asimpleparaboloid antenna by scanning thefeedispossible, butisgenerally limitedinanglebecauseofthedeterioration in theantenna patlernafterscanning butafewbeamwidths offaxis. 
 Since the receiver is tuned by changing the LO frequency, the narrowband filter milst be  tunable also.  A method of eliminating local-oscillator noise without the disadvantage of a narrow-  bandwidth filter is the balanced mixer (Fig. 9.2). 
 RANGE SEARCH  IS  INTERLEAVED WITH (02& 63 AND 273  AS SHOWN IN &IGURE   TO PROVIDE ALL ASPECT DETECTION 5NFORTUNATELY  BOTH 273 AND 623 HAVE POORER MAXIMUM DETECTION RANGE 2'(02& CAN PROVIDE ALL ASPECT DETECTION BUT TAIL PERFORMANCE IS  DRAMATICALLY POORER  DUE TO SIDELOBE CLUTTER %VEN WITH 34!0  WHICH SIGNIFICANTLY IMPROVES SIDELOBE CLUTTER REJECTION  LOW ALTITUDE TAIL ASPECT DETECTION FOR 2'(02& IS POORER   &)'52%  2'(02& RANGE 
 10.4) consists of a reference oscillator feeding a  balanced mixer. The input to the mixer is a signal of known frequency/ 0 and known phase ¢0  plus its accompanying noise. The reference-oscillator signal is assumed to have the same  frequency and phase as the input signal to be detected. 
 Rapid Scan (Phased Array) Radar.  Doppler weather radars that use phased array  antennas and complex waveform design may be applied to some of the more difficult  radar meteorology observations. The use of multiple doppler radars has provided dra - matic new information on the internal winds in large precipitating systems—information  that can be obtained in no other way. 
 T able 2. The simulation parameters of Figure 4. Parameters V alues Radar look direction 180◦ Incidence angle 23◦ Radar frequency C-band Polarization HH Platform height 800 km Platform velocity 7455 m/s 3. 
 SIDELOBE BEAM AND  THE DIFFERENCE OF THE TWO SQUINTED  BEAMS TO FORM A PRECISE  DEEP NULL AT BORESIGHT 4HE SUM BEAM IS USED ON BOTH TRANS 
 Tracking Radar   ........................................................ 18.1  18.1 Introducti on  .............................................................  18.1  18.2 Scanning and Lobi ng  .............................................. 
 In Proceedings of the 1994 IEEE National Radar Conference, Atlanta, GA, USA, 29–31 March 1994; pp. 132–137. 5. 
 The radar equation will also be considerably different if  clutter echoes or external noise, rather than receiver noise, determine the background with  which the radar signal must compete. Some of these other forms of the radar equation are  given elsewhere in this text.  Accuracy of the radar equation. 
 BISTATIC EQUIVALENCE v  0ROC )%%%   PP n  *ANUARY    h"ISTATIC RADARS HOLD PROMISE FOR FUTURE SYSTEMS v  -ICROWAVE 3YST .EWS   PP n   /CTOBER    - - 7EINER  h-ULTISTATIC RADAR PHENOMENOLOGY TERRAIN  SEA SCATTER v 2!$# 
 THE RADAR EQUATION 39  (c)  1  Figure 2.15 Polar plots of a,/a, for the two-scatterer complex target [Eq. (2.37)]. (a) I = 1; (b) 1 = 21;  (c) 1 = 4A. 
 Salmond, “Mixture reduction algorithms for target tracking in clutter,” SPIE , Signal and  Data Processing of Small Targets , vol. 1305, pp. 434–445, 1990. 
 7.6, is a more popular model for antenna design than the analytical models of  Table 7.1.)  An examination of the information presented in this table reveals that the gain of the  uniform distribution is greater than the gain of any other distribution. It is shown by Silver'  that the uniform distribution is indeed the most efficient aperture distribution, that is, the one  which maximizes the antenna gain. Therefore the relative-gain column may be considered as  the efficiency of a particular aperture distribution as compared with the uniform, or most  efficient, aperture distribution. 
 LATED QUITE ACCURATELY BY NUMERICAL METHODS  SUCH AS THE METHOD 
 The cross-range resolution cell dimension L(R) at range R is given  by LR D≈l where D is the receiving array aperture and l is the radar wavelength.  I. M ICROWA VE  RADAR II. 
 19.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 Precipitation Measurement.  Among the more important parameters to be  measured is rainfall, having significance to a number of water resource management  problems related to agriculture, fresh-water supplies, storm drainage, and warning of  potential flooding. The rainfall rate can be empirically related to the reflectivity factor  by an expression of the form108  Z = aRb (19.47) where a and b are constant and R is the rainfall rate, usually in millimeters per hour. 
 F. G. Bass, I. 
 Aircraft at  any altitude within this region can be detected, located, and tracked so as to provide a  cost-effective over-ocean air-traffic-control capability. Target height is not obtained with this  0TH radar. (Nor is height obtained with the usual microwave air-traffic-control radars.) It is  possible to utilize modified HF communications equipment as transponders on each aircrart  which can relay back to the radar the height of the aircraft as determined by the onboard  altimeter, as well as the identity of the aircraft. 
 ETRATING A MICROBURST FIRST EXPERIENCE AN INCREASE IN HEAD WIND AND THEN A CONTINU 
 It is convenient to plot the position of the grating lobes when the beam is phased for broadside and observe the motion of these lobes as the beam is scanned. Figure 7.10 shows the grating-lobe locations for both rectangular and triangular spacings. For a rectan- gular array the grating lobes are located at ^ Xcos axs - cosax = ± — p dxXcos oiys — cos ay = ± — q p, q = O, 1, 2,... 
 FIELD DISTRIBUTION THAT CAUSES HIGH SIDELOBES SINCE IT LOOKS  LIKE A TWO 
 The slope control determines the range scale and the zero-set resistors balance out the combined effects ofthe starting time ofthe switching square wave, the starting voltage ofthe sawtooth, and the conduction point ofthe diode. The critical circuit elements inaddition tothose in. Negative squareo- waveinput/ u$4.7k-lw “4100k.lw .&t, T0.01 1 24k.15w 10k.2w 500-2w !500.2w -2iv fl S,oy ~e~;--i$iyii--~ FIG.13.36.—Sawtooth delay circuit.;.E.type BOG156 t . 
 l ransmitfinq  onter1no  FM  I ransmitter  Receiving. Reference signal  on!enno  ~ Mi~er -Amplifier Li mil.er  Figure 3.11 Block diagram of FM-CW radar. CW AND FREQUENCY-MODULATED RADAR 83  Frequency  counter Indicator  Ideally, the isolation between transmitting and receiving antennas is made sufficiently large so  as to reduce to a negligible level the transmitter leakage signal which arrives at the receiver via  •.he coupling between antennas. 
 Thefrequency-response function ofthe matched filterhasbeenderived byanumber ofauthors usingeitherthecalculus ofvaria­ tions1ortheSchwartz inequality.9 Inthissectionweshallderivethematched-filter frequency­ response function usingtheSchwartz inequality. 5(t) t,t--- (a) h(t) (b)t-Figure10.1(a)Received waveforms(t);(b)impulseresponse h(r)ofthematched filter.. 372 INTRODUCTION TO RADAR SYSTEMS  We wish to show that the frequency-response function of the linear, time-invariant filter  which maximizes the output peak-signal-to-mean-noise ratio is  when the input noise is stationary and white (uniform spectral density). 
 The ring projects slightly into the cavity. The ring is split, with  the split diametrically opposite the output cavity. The ring is also cut to accommodate the  output coupling slot. 
 A fixed bandwidth technique for increasing range resolution  and the number of independent samples is the process of sampling the transmit pulse at  an interval several times shorter than its duration and using a linear predictive whitening  filter  97 to remove the correlated information from the oversampled data.98,99 This whit - ening process increases the number of independent samples for range averaging that  allows improved parameter estimation accuracy but at a cost of significantly reduced  SNR. The higher noise bandwidth in the receiver required by the higher rate sampling  and the whitening filter noise enhancement cause the SNR to be reduced by a factor of  approximately L2 where L is the increased sampling factor.100 Stated another way, the  whitening filter effectively shortens the transmit pulse (by L) while passing the increased  receiver noise power (by L) thereby trading range resolution for SNR. Fortunately, for  precipitation echoes and typical weather radars, the SNR is quite high, and even after  the whitening process, it remains high enough to effectively utilize the larger number  of independent samples for improved base data estimates or improved range resolu - tion measurements.101 On the other hand, if the signal is weak, noise enhancement will  dominate the whitening process and any advantage is lost. 
 An example of the accuracy is as follows: A system with 14.4 hits per beam - width, a four-pulse binomial weight canceler, and a 6:9:7:8 pulse-interval ratio has an  improvement factor limitation of 36.5 dB due to staggering. The curve gives a limita - tion of 37.2 dB for this case. But if the sequence of pulse intervals were to be changed  from 6:9:7:8 to 6:8:9:7, the actual limitation would be 41.1 dB, which is 3.9 dB less  than that indicated by the curve. 
 The output of the matched filter consists of the compressed pulse accompa- nied by responses at other ranges, called time or range sidelobes. Frequency weighting of the output signals is usually employed to reduce these sidelobes. This results in a mismatched condition and leads to a degradation of the signal- to-noise output of the matched filter. 
 This equation was derived for a gaussian beam shape but is essentially independent of the actual beam shape or aperture illumination func- tion used. The clutter spectral spread due to scanning, normalized to the PRF, isSource of clutter Sparse woods Wooded hills Wooded hills Wooded hills Wooded hills Sea echo Sea echo Sea echo Sea echo Chaff Chaff Chaff Rain clouds Rain cloudsWind speed, kn Calm 10 20 25 40 8-20 Windy 25a v, m/s 0.017 0.04 0.22 0.12 0.32 0.7 0.75-1.0 0.46-1.1 0.89 0.37-0.91 1.2 1.1 1.8-4.0 2.0Reference Barlow1 Goldstein,3 pp. 583-585 Barlow1 Goldstein,3 pp. 
 But there is no point in considering shape  control unless a specific threat direction can be identified in azimuth or elevation  or both. If all directions are equally likely, then the advantage of choosing favor - able surface orientations for one threat direction is canceled by an accompanying  enhancement in another. In many situations, however, the general direction of the  threat can be forecast. 
 Time shift of fdT/B is  introduced by range- doppler coupling for a  nonsymmetrical NLFM  waveform. Common,  therefore, in ATC  radars. Multiple tuned  pulse compressors  required for high-speed  targets.Higher sensitivity to  doppler shift. 
 It would have been easy to double the size of this edition even without increasing the number of chapters. The limitation on size was one of the reasons a number of chapters found in the first edition do not appear here. Some of the omitted chapters were concerned with subjects for which there is not as much interest as there had been or whose technology has not advanced as much as other areas of radar. 
 6 
 The art advanced sorapidly inthe early years that manufacturers were often called upon tomake major changes during the course ofproduction in order totake account ofnew lessons from both thelaboratories and the battlefields. The growth oftheradar industry, which scarcely existed before 1940, isindicated bythe fact that bythe end ofJune 1945, approximately $2,700,000,000 worth ofradar equipment had been delivered totheArmy and the Navy. Atthe end ofthe war, radar equipment was being produced atarate ofmore than $100,000,000 worth permonth. 
 HEIGHT MEASUREMENT OBJECTIVES OF SPACE 
 Full details onthe phase-shift unit can befound ina report byV.A.Olson. 1 The doppler frequency depends ontheradial component ofvelocity and istherefore proportional tothe cosine ofthe azimuth angle. Itis necessary tovary the frequency ofthe doppler oscillator automatically astheantenna scans. 
 pp. 151-160, May, 1977.  66. 
 NOISE RATIO 3.2  !S DISCUSSED BELOW  THE MATCHED FILTER IS FOLLOWED BY A WEIGHTING FILTER IF REQUIRED FOR REDUCTION OF TIME SIDELOBES 4HE OUTPUT OF THE PULSE COMPRESSION FILTER IS APPLIED TO AN ENVELOPE DETECTOR  AMPLIFIED BY THE VIDEO AMPLIFIER  AND DISPLAYED TO AN OPERATOR 4HE RATIO OF THE TRANSMIT PULSEWIDTH TO THE COMPRESSED PULSE MAINLOBE WIDTH IS  DEFINED AS THE PULSE COMPRESSION RATIO 4HE PULSE COMPRESSION RATIO IS APPROXIMATELY 4"  OR  4"  WHERE  4" IS DEFINED AS THE TIME 
 21.1. In order to achieve the resolution indicated by Eq. (21.8), the synthetic ap- erture length required is Lef[=™ (21-14) The considerations used in arriving at Eq. 
 OF 
 TRACKING PORT ION OF THE RADAR HAS THE  ADVANTAGE OF SEEING ALL TARGETS WITHIN THE BEAM FROM CLOSE RANGE OUT TO THE MAXIMUM RANGE OF THE RADAR )T TYPICALLY BREAKS THIS RANGE INTO SMALL INCREMENTS  EACH OF WHICH MAY BE SIMULTANEOUSLY EXAMINED FOR THE PRESENCE OF A TARGET 7HEN BEAM SCANNING IS NECESSARY  THE RANGE TRACKER EXAMINES THE INCREMENTS SIMULTANEOUSLY FOR SHORT PERIODS  SUCH AS  S  MAKES ITS DECISION ABOUT THE PRESENCE OF A TARGET  AND ALLOWS THE BEAM TO MOVE TO A NEW LOCATION IF NO TARGET IS PRESENT 4HIS PROCESS IS TYPICALLY CONTINUOUS FOR MECHANICAL 
 TERED  HOWEVER  QUAD 
 1975.. CHAPTER  FIVE  TRACKING RADAR  5.1 TRACKING WITH RADAR  A tracking-radar system measures the coordinates of a target and provides data which nlay be  used to determine the target path and to predict its future position. All or only part of the  available radar data-range, elevation angle, azimutll angle, and dopplcr f~.cqi~crlcy sllift  may be used in predicting future position; that is, a radar might track in range, in aoglu. 
 Fox, A. P. Luscombe, and A. 
 FORM   BUT IN GENERAL  NUMERIC INTEGRATION IS REQUIRED -AIN 
 the improvement factoris (4.25) (4.26)Similarly. foradoublecanceler. whoseaverage gainis6,theimprovement factoris f/ fp4).4a2fp412c""_.._-=--~-=-- -8rr4a: l28rr4a~ 2n4fo4 !\plotofEq.(4.26)forthedouhlecanceler isshowninFig.4.30.Theparameter describing the curvesisfpA.Example pre'sandfrequencies areshown.Several" representative" examples of clutterareindicated, basedonpublished dataforav,whichforthemostpartdatesbackto WorldWar11.46.49Although eachtypeofclutterisshownataparticular valueofav,natureis morevariable thanthis.Actualmeasurements coverarangeofvalues.Thespectral spreadin velocity iswithrespecttothemeanvelocity, whichforgroundclutterisusuallyzero.Rainand Sparse woods 60- 50rou 240uo- C Ql ~30- >o....0. 
 , 
 Simulations have predicted the following maximum and minimum temperatures for selected parts of the space-fed lens antenna: By choosing the proper materials, the design of this class of antenna will experi- ence low distortions compared with those allowable. Figure 22.632'33 shows the loss in relative gain for a 71-m-diameter space-fed antenna as a function of theERROR CORRELATION INTERVAL » XLOSS OF GAIN (dB) Location Ground plane Rim Upper stays Lower stays Upper dipole plane Lower dipole planeTemperature, K Maximum 264 182 231 217 314 274Minimum 224 160 186 201 201 220 . FIG. 
 The bandwidth ofthe amplifier must besufficient toavoid serious impairment ofsystem resolution and the loss ofsystem signal-to-noise. 1 Inaddition, thebandwidth ofthedelayed and undelayed channels must besufficient tomake the interchannel balance noncritical. Bandpass unbalance will have relatively little influence upon pulse shape ifthe bandwidth ofeach split channel isperhaps twice that ofthe over-all system. 
 Radar backscatter by its very nature is a quantity having a large  standard deviation that can be reduced only by extensive averaging. Because the geophysical interpretation of scat - terometric data often depends on distinguishing between two similar values of s  0, the results depend critically on  reducing the uncertainty in the estimated value as well as getting the average value right. ch18.indd   53 12/19/07   5:15:14 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 One major advantage of pulse doppler over CW systems is the time blanking of transmitter leakage so that receiver sensitivity is not degraded owing to saturation effects or to noise sidebands on the transmitter. Harmonic Frequencies. Extreme care is required to prevent spurious signals from appearing in the system output. 
 PLATE SCATTERING FROM THE INDIVIDUAL FACES !LONG THE AXIS OF SYMMETRY OF THE TRIHEDRAL REFLECTOR IN &IGURE   P   n  E   n   THE  2#3 IS O, K  WHERE , IS THE LENGTH OF ONE OF THE EDGES OF THE APERTURE .OT  SHOWN ARE THE ECHO REDUCTIONS OBTAINED WHEN THE TRIHEDRAL FACES ARE NOT PERPEN 
 23-52, January 1980. 9. Ausherman, D. 
 WA-5, pp. 1.1–1.5, 1982. 31. 
 (1.7)] these two roles were expressed by the trans-  mitting gain and the effective receiving aperture. The two parameters are proportional to one  another. An antenna with a large effective receiving aperture implies a large transmitting gain. 
 OTI-IER RADAR TOPICS 533  Range resolurion-could be as low as 2 km, but is more typically 20 to 40 km.  R~lati~~e rairge accurac~~--typically 2 to 4 km for a target location relative to a known location  ohserved by tlie same radar.  Ahsolrtte rurtye ucc.~rac)~-- IO to 20 kin, assutning real-time analysis of tlie propagatiori path is  made. 
 Spurious responses not predicted by the chart occur when two or more RF input sig - nals produce other frequencies by intermodulation that lie within the RF passband. Image-Reject Mixer.  A conventional mixer has two input responses at points  above and below the LO frequency where the frequency separation equals the IF. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 1.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 ● The use of the doppler frequency shift to detect moving targets in the presence of  much larger echoes from clutter. 
 The surface wave tends to build  up toward the rear of the body and is usually reflected back toward the front by any  discontinuity at the rear. Traveling-wave echoes at low grazing angles are nearly as  significant as specular echoes at normal incidence. Tip, Edge, and Corner Diffraction. 
 The rate of subsidence is shown in Figure 11and severe subsidence are detected. Four typical PS points (i.e., H, I, J, and K) are selected to analyze the subsidence (Figure 11). Figure 11. 
 J. Doviak, M. Sachidananda, and D. 
 If exact knowledge of the  doppler frequency is not necessary, earphones are especially attractive provided the doppler  frequencies lie within the audio-frequency response of the ear. Earphones are not only simple  devices. but the ear acts as a selective bandpass filter with a passband of the order of 50 Hz  centered about the signal frequency.2 The narrow-bandpass characteristic of the ear results in  an effective increase in the signal-to-noise ratio of the echo signal. 
 KM DISTANCE  &OR GEODETIC SIGNALS THAT ARE EXPRESSED THROUGH STATIC SEA 
 The meter does not measure the loss of subclutter visibility due tofluctuations intheclutter produced byscan- ning orthewind. Itmeasures only thequantity K,inEq. (28).. 
 (13.8). Another effect is re- lated to the fact that the excitation of the surface-wave system depends on the apparent wind; so there can be significant differences in waveheight according as the wind is blowing with or against the current. According to Eq. 
 This loss in the forward wave can be avoided by the use of  discontinuities called severs, which are short internal terminations designed to dissipate the  reverse-directed power without seriously afTecting the forward power.13 The number of severs  depends on the gain of the tube; one sever is used for each 15 to 20 dB of gain. In addition lo  reflection-type oscillations, backward-wave oscillations can occur. These frequently occur  outside the p~ssband so that they can be reduced by loss that is frequency selective.13  In principle, the traveling-wave tube should be capable of as large a power output as the  klystron. 
 Pioneer Venus  was host to 17 experiments (with a total mass of 45 kg), including a  radar altimeter (ORAD), which also produced rudimentary surface maps as the radar  beam was scanned in the plane orthogonal to the orbit by the spacecraft’s 5 RPM spin- stabilization. The radar package required an average 18 W input power and had a mass  of 9.7 kg. Peak transmitted power was 20 W. 
 Busli, T. F., and F. T. 
 DELAY CANCELER . 
 TIONS WITH EXISTING TRACKS !LSO  THE ABILITY TO CORRECTLY ASSOCIATE DETECTIONS WITH EXISTING TRACKS AFFECTS THE TRACKS ACCURACY AND THE ABILITY TO CORRECTLY DISTINGUISH BETWEEN AN EXIST 
 Shaping of the high-resolution central spike area as well as the gross structure of the  ambiguity surface can be accomplished by variations of the basic waveform param - eters, such as amplitude weighting of the pulse train, staggering of the pulse repetition  interval, and frequency or phase coding of the individual pulses.39  Costas Codes.  Costas codes are a class of frequency-coded waveforms that  have near ideal range and doppler sidelobe behavior.40,41 In other words, their ambi - guity function approaches the ideal thumbtack, providing both doppler and range  information (Figure 8.25). All sidelobes, except for a few near the origin, have  an amplitude of 1/ M. 
 For simplicity, weshall assume that the antenna Aconstitutes a matched load onthetransmission line ofcharacteristic impedance Z,the latter being terminated atthe other end intheresistor BC, whose resis- tance Rneed not beequal toZ. The box Disanideal amplifier of bandwidth c%,equipped with anoutput meter E,whose reading ispropor- tional tothe mean square voltage ~across BC. The bar asbefore denotes atime average, or,more explicitly, anaverage over atime long compared with 1/@. 
 S. Chang and V . V . 
 The radars were soon upgraded to ASV Mk. IIIA, designated ARI 5153, which is described here. A good technical description can be found in [ 4], produced by the Air Ministry in November 1943. 
 IT- 10, pp.61- 67, January 1964.  [6] Key, E.L., Fowle, E.N., and Haggarty, R.D., "A Method of Designing Signals of Large Time Bandwidth Product", IRE International Co nvention Record , Part 4,  pp.146- 154,1961.  [7] Worley, J.C., "Implementation of Nonlinear FM Pulse Compression Filters U sing  Surface Wave Delay Lines", Proceedings IEEE , vol. 
 ORDERv CONTRIBUTIONS TO THE SCATTERED FIELD ARISE FROM ONLY TWO  OCEAN WAVE TRAINS   NAMELY THOSE WHOSE  WAVE VECTORS SATISFY  THE RELATION  FFF Jo o 
 Ta~ lor aperture illumination. The Taylor aperture illumination is a r ~alizable approximation to  the Dolph-Chcbyshev illumination.84 It produces a pattern with uniform sidelobes of a  specified value. but only in the vicinity of the main beam. 
 NOISE RATIO 4HE AMPLITUDE AND PHASE WEIGHT FOR THE SIGNAL AT EACH RECEIVER IS ADAPTIVELY COMPUTED AND IMPLEMENTED SO THAT THE DESIRED SIGNAL COMBINES COHERENTLY WHEREAS THE INTERFERENCE COMBINES INCOHERENTLY &)'52%   $ETERMINISTIC ANTENNA PATTERN WITH AND WITHOUT  NULLING FOR A  
 200–206, 1977. ch16.indd   59 12/19/07   4:56:49 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 To save memory, the cells are usually  updated by using a simple recursive (single-pole) filter of the form  y i y i x i ( ) ( ) ( ) ( ) = − ⋅ − + ⋅ 1 1α α (2.61) where y(i − 1) is the clutter map amplitude from the previous scan, y(i) is the updated  clutter map amplitude, x(i) is the radar output on the present scan, and the constant   a  determines the memory of the recursive filter. The test for detecting a target based  on the output x(i) is  x i k y iT ( ) ( ) ≥ ⋅ −1 (2.62) where the threshold constant kT is selected to give the required false-alarm rate.  Alternatively, the radar output can be normalized on the basis of the clutter map  content to obtain an output z ix i y i( )( ) ( )=−1, which can be processed further if required. 
 090 - r;: 0 80  g O 70  u % 060  "O  -050  0  :;;::. 0 40 ·  15 o 30 ·  0 .0  !:.' 0 20 a.  010  0  0  0 01  -10 -i- 0 5 15 20 25 30  Signal to noise roho per pulse dB  Figure 2.25 Comparison of detection probabilities ror Rice, log normal, chi-square with m = 2 (Swerling  case J) and nonfluctuating target models with "= 10 hits and false-alarm number n1 = 106• Ratio of  dominant-to-background equals unity (s = 1) for Rice distribution. 
 21.8 SIGNAL AND IMAGE PROCESSING The three basic permutations of GPR data presentation are shown in Figure 21.24. The  most basic GPR data record is an A-scan. An A-scan provides amplitude-time record  of a single measurement over a target. 
 11.29 aspart ofanr-ftransmitting and receiving system. The TR-tube input window isincontact with thenarrow side ofthe waveguide. From the resemblance ofawaveguide toastub- supported two-wire transmission line, illustrated inFig. 
 h–σpdcurve. σpdrepresents the phase error due to the di ﬀerence in phase distortion of the SAR image pair. 5.1.3. 
 A. Alperin, R. R. 
 On striking the diode, which is reverse biased well below the  avalanche threshold, each impacting electron gives rise to thousands of additional carrier pairs  to provide a current amplification of 2000 or more. A control grid is inserted between the  cathode and the diode to density-modulate the electron beam. (The basic geometry is similar  to that of the classic triode vacuum tube, but with a semiconductor diode as the plate.)  The EBS can also be deflection-modulated by varying the position of the beam relative to two  or more separated semiconductor targets whose outputs are combined. 
 J. Remote Sens. 2017 ,38, 6457–6476. 
 Mission objectives include  polarimetric diversity and interferometry. The two baseline multi-look resolutions are  3 m (40-km swath) and 20 m (100-km swath), over a variety of incident angles. Its  antenna is an active phased array. 
 Onsome occasions, however, thereduc- tion ofechoes from certain areas ofthestorm hasbeen negligible despite atangential wind velocity. The wooded terrain isthat ofNew England insummer. Limited evidence suggests that there islittle change with theseasons. 
 Frequency is 1300 MHz (L band) with linear  polarization. V V = vertical polar~rat ion,  HH = horizontal polarization. (b) Eleva- I  tion-variation nose-on (azimuth = 0") (c)  Elevation-variation tail-on (azimuth=  180"). 
 It is less efficient than ideal postdetection  integration, but it has the advantage of simplicity. It is called the binary moving-window  detector, but it has also been called double-threshold detector, m-out-of-n detector, coinci­ dence detector, sliding-window detector, and binary integrator.  A bloc!< diagram of the binary moving-window detector is shown in Fig. 
 2014 ,22, 98–109. [ CrossRef ] 20. Dekker, R.J. 
 The velocity response curve is symmetrical about  one-half of the value from Eq. 2.36. Feedback and Pulse-to-Pulse Staggering. 
 The distance from the aircraft to the point target can be expressed as: R(tm)=/radicalBig R2 b+( vtm−Xi)2(7) where tmis the azimuth slow-time. Assuming that the transmitted signal is a LFM signal, the received baseband echo signal is [ 17]: s0(tr,tm)= A0ωr/parenleftbigg tr−2R(tm) c/parenrightbigg ωa(tm−tmc)exp/braceleftbigg −j4πfcR(tm) c/bracerightbigg exp/braceleftBigg jπγ/parenleftbigg tr−2R(tm) c/parenrightbigg2/bracerightBigg (8) where A0is the amplitude of the signal, ωr(·)is the range envelope, tris the range fast time, ωa(·) is the azimuth envelope, tmcis the center of synthetic aperture time, fcis the center frequency of the transmitted signal, and γis the chirp rate of the chirp signal. A two-dimensional FFT is applied to the echo signal, and the two-dimensional frequency domain expression can be obtained: S2DF(fr,fa)=A1Wr(fr)Wa(fa−fac)exp{jθ2DF(fr,fa)} (9) where θ2DF(fr,fa)=−4πRb(fc+fr) c/radicaltp/radicalvertex/radicalvertex/radicalbt1−(cfa)2 4(fc+fr)2v2−πf2 r γ−2πfaXi v(10) Wa(fa)=wa⎛ ⎝−cR0fa 2(fc+fr)v2/radicalbigg 1−c2f2a 4v2(fc+fr)2⎞ ⎠is the envelope of the azimuth spectrum, and Wr(fr)=ωr(fr γ) is the envelope of the range spectrum. 
 Radar Conf. Rec ., pp. 5.22–5.29, May 6–9, 1985. 
 One is the incident field, and the other is the scat- tered field. The formation of the shadow implies that the forward scattering is large, which is indeed the case. The fields behind the target are hardly ever pre- cisely zero, however, because some energy usually reaches the shadow zone via diffraction from the sides of the target. 
 SHIFTED SIGNAL DUE TO THE RELATIVE MOTION OF THE CLUTTER 4HE POWER RECEIVED BY THE ELEMENT IS PROPORTIONAL TO THE TWO 
 Theaperture illumination function thatwouldnormally beconsidered foraconventional antenna isusedasthemodelfordetermining thedensityofequal-amplitude elements. Thatis, thedensityofequal-amplitude elements ismadetoapproximate thedesiredaperture illumina- ,.; tion.Thechoiceofelementlocations toachievethedesireddensitydistribution maybemade oneitherastatistical basisordeterministically. Onepossibleapplication ofdensitytaperisin atransmitting arraywhereitisdesiredtoradiateequalpowerfromeachelement, butwhere thehighpeak-sidelobe oftheuniform illumination isnotacceptable. 
 23-25, 1973, IEE Conf Plthl. no. 105, pp. 
 In contrast to the array factor, this pattern has only one maximum and is nonrepetitive. It is the well-known Fourier transform of a con- tinuous constant-amplitude distribution and is a reasonable approximation for small values of 9 when the aperture is greater than several wavelengths. The half- power beamwidth is obtained from Eq. 
 when used for this purpose. it called ari c~cqtristiott rcldclr. The acquisitiori radar ciesig-  rwtes targets to the tracking radar by providing tlie coordinates where the targets are to be  fourid. 
 Inc.  The coriiputer riiust be capable of responding to the immediate demands of high-priority  tasks with061 throwing away the results of partially completed lower-priority tasks. The r.xucrc-  lircl proyrclrtl must recognize the presence of a high-priority task and initiate it properly. 
 Few modern receivers have been designed for CW target illuminators since many installations avoid the use of a separate receiver. With space in the nose of an aircraft at a premium, it is usual for airborne missile systems to employ a com- mon antenna for both the tracking radar and the illuminator.71 In some shipboard weapon systems, the illuminator does not require a receiver since the illuminator antenna is pointed to the direction of the target from information obtained by the tracking radar of the weapon control system rather than have the illuminator track the target itself. Generation of the Local-Oscillator Signal. 
 MENT OF THE 3TRETCH TECHNIQUE   WHICH IS KNOWN AS  FULL DERAMP IN THE FIELD OF SPACE 
   * (ARMON  h4RACK BEFORE DETECT PERFORMANCE FOR A HIGH 02& SEARCH MODE v IN  )%%% .ATIONAL  2ADAR #ONFERENCE   PP n  * 2 'UERCI   3PACE 
 The ideal image demonstrates the excellent performance of sliding spotlight mode in high-resolution SAR imaging. The scintillation strength in Figure 11b,c are CkL=1033and CkL=1034which refers to the moderate and strong strength of scintillation. Other ionospheric parameters are shown in Table 1as the default value. 
 In Fig. 10. Ia9 the coded signal is obtained by exciting the coding filter //(<*>) with a unit impulse. 
  
 Air Force,   AFR 55-44; U.S. Army, AR 105-86; and U.S. Marine Corps, MCO 3430.1. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 19.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 Since the total-attenuation cross section52 depends on the temperature (because of  its effects on the dielectric properties of water), it is important to evaluate the attenu - ation of rains whose drops are at different temperatures from those in the preceding  tables. 
 The minimum level of solar noise is due to blackbody radiation at a tempera­ ture or about 6000 K.56Y7 The solar noise is unlike most other noise mechanisms in that its  power increases with increasing frequency. Solar storms (sunspots and flares)can increase the  solar-noise level several orders of magnitude over that of the "quiet," or undisturbed sun.  The solar noise can sometimes be of significant magnitude to affect the sensitivity of low-noise  radar receivers from energy received in the antenna sidelobes. 
 (a) General case; (b)cathode followers; (c)cable-matching. Several types ofnegative-feedback amplifiers are used inindicator circuits. Cathode Feedback.—A simple variety ofnegative-feedback circuit uses anunbypassed cathode resistor toprovide the feedback voltage (Fig. 
 Examples of the theoretical bistatic cross section of a sphere are shown in Fig. 14.13.  Comparison of bistatic and monostatic radars. 
 The transmitted spectrum of a pulse doppler radar con - sists of discrete lines at the carrier frequency f0 and at sideband frequencies f0 ± ifR, where  fR is the PRF and i is an integer. The envelope of the spectrum is determined by the pulse  shape. For the rectangular pulses usually employed, a sin( x)/x spectrum is obtained. 
 14”25); (2)only the voltage toberegulated has abooster winding; and (3)thevoltage tobe regulated isgenerated entirely inthe windings ofthe booster armature. The third method ispractical only forlow voltages, because ofthelarge number ofturns and relatively high field current required togenerate a high voltage. 1 Over ranges ofinput voltage from 25to29volts, from noload to full load onthe dynamotor, the output-voltage change will beapproxi- mately 3per cent. 
 7.6 permit the antenna  designer to compute the aperture illumination required to achieve a specified radiation  pattern. However, when the antenna is constructed, it is usually found that the experimentally  measured radiation pattern deviates from the theoretical one, especially in the region of the  sidelobes. Generally, the fault lies not with the theory, but in the fact that ii is· not possible 10  reproduce precisely in practice the necessary aperture illumination specified by synthesis  theory. 
 ALLY OCCURS IN THE  (Z TO  K(Z OFFSET REGION &REQUENCY 3YNTHESIS 4ECHNIQUES  4HE MOST COMMON TECHNIQUES ARE DIRECT  SYNTHESIS  DIRECT DIGITAL SYNTHESIS  AND FREQUENCY MULTIPLICATION $IRECT SYNTHESIS IS THE PROCESS OF GENERATING FREQUENCIES THROUGH THE MULTIPLICATION AND MIXING OF A NUMBER OF SIGNALS AT DIFFERENT FREQUENCIES TO PRODUCE THE REQUIRED OUTPUT FREQUENCY &REQUENCY MULTIPLICATION AND DIRECT DIGITAL SYNTHESIS ARE DESCRIBED IN 3ECTION  #ONVENTIONAL PHASE LOCKED LOOP SYNTHESIZERS ARE OCCASIONALLY USED  BUT THEIR FRE 
 7.3 AUTOMATIC TRACKING A track represents the belief that a physical object or “target” is present and has actu - ally been detected by the radar. An automatic radar tracking system forms a track when  enough radar detections are made in a believable enough pattern to indicate a target is  actually present (as opposed to a succession of false alarms) and when enough time has  passed to allow accurate calculation of the target’s kinematic state—usually position  and velocity. Thus, the goal of tracking is to transform a (time-lapse) detection picture  (shown in Figure 7.24 a), consisting of target detections, false alarms, and clutter, into  a track picture (shown in Figure 7.24 b), consisting of tracks on real targets, occasional  false tracks, and occasional deviations of track position from true tar get positions. 
 15.3 and discussed in detail in Sec. 15.2 uses a single-delay canceler. It is possible to utilize more than one delay and to introduce feedback and/or feedforward paths around the delays to change the MTI system response to targets of different velocities. 
 Ferrite limiter. The ferrite limiter46 followed by a diode limiter, has also been employed as a  solid-state receiver protector.40•45 The·diode is necessary to reduce the spike leakage to a safe  level since the ferrite acting alone does not offer sufficient suppression of the spike leakage at  high peak power. The ferrite diode limiter has fast recovery time (can be as low as several tens  of nanoseconds), and if the power rating is not exceeded, the life should be essentially un­ limited. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation. 26.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 While waveguide models are most useful for conditions where the vertical refractiv - ity profile does not change along the propagation path (homogeneous environments),  they can be applied to inhomogeneous environments by breaking the waveguide up  into slabs in a technique known as mode conversion . 
 PENDENT OF CLUTTER SPECTRAL SPREAD 4HE FIVE 
 S ANTENNA 4HE 3!2 
 This equation was derived by substituting for kT0Fn in Eq. (1.7) the jamming noise power per unit band- width that would enter the radar receiving-antenna sidelobes. It applies only when the normal receiver noise is negligible compared with the jamming noise. 
 - /bw to /t + /bw 2/JO.h'!)1" /m(0.1i!)w No requirement (for natural sampling)ymQ fmQNo require- mentTarget SNR loss [/!V ' K5I(CIN)]1HClutter spreadingl/trT; to £„/2 2/JO.l/!)17'' /m(0.1/!)^ No requirement (for natural sampling) 2/mC /«GNo require- mentTarget SNR loss D'V^/IC/N)]1"'Clutter spreading^/2to/min . 2iG T(2 2TC 2/mC /mG 20 V^/(maxSA«) False targets 5Bn to/min 2r(2 TS 2rC 2/mG /mG 2G ^/ KJ(CIN)Clutter spreading /,,,in and higher /bw = tracking-loop noise bandwidth, Hz ^TA/ = modulation sensitivity (fractional modulation/ beamwidth or pulse-width error) VE = rnis tracking error due to modulation sidebands 6 = antenna beamwidth max SNR = maximum target power SNR that does not cause automatic gain control or limiting i = integer part of [(BJ2) + /m]//m ; = integer part of (/^1n + /m)//m 8A = peak fractional pulse-amplitude modulationM = peak fractional carrier amplitude modulation 8F = peak carrier frequency deviation, Hz /m = modulating frequency, Hz Tc = two-way delay for main-beam clutter, s 8n/ = peak pulse-width deviation, s ^min = minimum target signal duty cycle when partly eclipsed (sny, T/R/5) S7, = peak pulse-position deviation, s Kx = safety factor of modulation power sidebands relative to system noise (Kx < 1) fL = tracking subcarrier frequency, Hz . Applying all these constraints to the various types of modulations expected gives the sinusoidal modulation allowances of Table 17.5 where 0.1 dB tolerable loss was assumed in SNR. 
 42,  pp. J 262-126 7, August, 1954.  14. 
 The latter is called a coherent (heterodyne) receiver or photomixer. When the  background noise is low and for short-pulse modulation the laser envelope detector can  operate as a quantum-limited device and give essentially the same detectivity (inverse of the  noise equivalent power) as heterodyne detectors.85 (This is unlike microwaves where the video  detector is far less sensitive.) The heterodyne, or photomixing, receiver can have a narrow  passband and significantly reduce the effects or background noise. Its sensitivity also can  approach that of an ideal quantum detector. 
 14.5 of ref. 47.  61. 
 !   2 7 ,ARSEN  ! , -AFFETT  2 # (EIMILLER  ! & &ROMM  % , *OHANSEN  2 & 2AWSON  AND & ,  3MITH  h"ISTATIC CLUTTER MEASUREMENTS v )%%% 4RANS !0 
 BAND RADAR ITSELF  WHICH SITS ON TOP OF THE FLOATING PLATFORM  IS THE LARG 
 .3I7,3.18, 319, and 320. inFig. 317, forexample, the positi(m ofthe aircraft (given bythe spot atthe center ofthe pict~lre) c:tn immetii:~tely be identifie(l I)yrcfrr(,nr(’ tothe ()akl:ln(l 1!att,rfrt)nt. 
 Considerable bandwidth (perhaps 50 percent) can be obtained, even with patch radiators, provided they are fed similarly to a dipole.25 For limited scanning (say, less than 10°), it is possible to use directive radia- tors having dimensions of height and width of several wavelengths. With such separation, the mutual coupling effects can be small, and the pattern and imped- ance of an element in the array approach those of the isolated element. The element must be chosen to give the desired polarization, usually vertical or horizontal. 
 DELAY NETWORKS WILL CHANGE WITH FREQUENCY AND THE BEAM WILL REMAIN STATIONARY 7HEN PHASE SHIFT INDEPENDENT OF FREQUENCY  IS USED TO STEER THE BEAM  THE BEAM IS  STEERED TO A DIRECTION P  WITH A PHASE OF   YP LP    XX CFSIN SINPP   ON  THE ELEMENT LOCATED A DISTANCE  X FROM THE ARRAY CENTER !T FREQUENCY  F THIS SAME  PHASE SETTING STEERS THE BEAM TO A NEW DIRECTION   P   $P  WHICH IS SHOWN IN &RANK  TO BE   $$PP F FTAN RAD     !S  THE FREQUENCY IS INCREASED  THE BEAM SCANS TOWARD BROADSIDE BY AN ANGLE  THAT IS INDEPENDENT OF THE APERTURE SIZE OR BEAMWIDTH (OWEVER  THE PERMISSIBLE  AMOUNT THAT THE BEAM MAY SCAN WITH FREQUENCY IS RELATED TO THE BEAMWIDTH BECAUSE PATTERN AND GAIN DETERIORATIONS ARE A FUNCTION OF THE FRACTIONAL BEAMWIDTH SCANNED  4HE ANGLE THAT THE BEAM ACTUALLY SCANS  ON THE OTHER HAND  IS RELATED TO THE PER 
 8.3 PHASE SHIFTERS  The difference in phase 4 experienced by an electromagnetic wave of frequency f propagating  with a velocity r through a transmission line of length I is  4 = 27tf'll~ (8.15)  The velocity 1: of an electromagnetic wave is a function of the permeability 1, ancl the dielectric  constant ( of the medium in which it propagates. Therefore, a change in phase can be had by a  change in the frequency;length of line, velocity of propagation, permeability, or dielectric  constant. The use of frequency to effect a change of phase is a relatively simple technique for  electronically scanning a beam. 
 A target located at the maximum of a  Figure 12.2 Vertical. lobe structure caused by the presence  of a plane reflecting surf ace. 444 INTRODUCTION TO RADAR SYSTEMS  particular lobe will be detected at a range twice that of the same radar located in free space. 
 Sim ilarly, multifunctional software -defined radios  (SDR), fulfilling the process ing needs of diffe rent mobile communications standards and ser v- ices, are under development at many places worldwide. SDRS and SD -SAR will benefit from  them.   The future of Radar remote sensing hardware will be digital. 
 This restricts the sector that is blanked by main- beam jamming and also provides a strobe in the direction of the jammer. Strobes from  a few spatially separated radars allow the jammer to be located. The availability of solid-state transmitter technology36–40 allows the generation of  high duty cycle waveforms, which may be of some help to realize LPI radar . 
 3 x 103 x 0.1 x 103 x 0.1 = 3.0 x 104m2 or 45 dB Suppose that there is present a target at a greater range and that a +22-dB signal-to-noise ratio in a 1-kHz bandwidth is needed to have a suitable probability of detection with an acceptable probability of false alarm (this includes allowance for a + 10-dB receiver noise figure). If the target produces a 10-kHz doppler sig- nal, the noise of the clutter signal must not exceed -144 dBm* + 22 dB = -122 dBm at the 10-kHz offset. If a transmitter is assumed in which the noise sidebands in a 1-kHz bandwidth are 103 dB below the carrier, the clutter signal must not exceed -19 dBm. 
 MENTS WILL BE WIDEBAND  HARMONIC FILTERS MAY BE REQUIRED &OR EXAMPLE  ONE TRANSMIT 
 Golino, L. Timmoneri, and G. Tonelli, “Digital equalisation in adaptive spatial  filtering for radar systems: Application to live data acquired with a ground-based phased-array  radar,” Radar 2004 , Toulouse, France, October 19–21, 2004. 
 ATED FROM ABOUT  TO OVER  -(Z IN  VARIOUS MODELS 2ADARS AT SUCH FREQUENCIES  WERE NOT AFFECTED BY THE COUNTERMEASURE CALLED CHAFF ALSO KNOWN AS WINDOW  5(&  TO  -(Z   -ANY OF THE CHARACTERISTICS OF RADAR OPERATING IN THE  6(& REGION ALSO APPLY TO SOME EXTENT AT 5(& 5(& IS A GOOD FREQUENCY FOR !IRBORNE -OVING 4ARGET )NDICATION !-4)  RADAR IN AN !IRBORNE %ARLY 7ARNING 2ADAR !%7   AS DISCUSSED IN #HAPTER  )T IS ALSO A GOOD FREQUENCY FOR THE OPERATION OF LONG 
  D" RESULTS IN AN APPROXIMATELY  D"  SENSITIVITY LOSS 4HIS ASSUMES A WORST 
 C'osgriff, R. L.. W. 
 BASED PULSE COMPRESSION SYSTEMS FOR RADAR APPLICATIONS v  %LECTRONICS   #OMMUNICATIONS %NGINEERING *OURNAL  $ECEMBER   2 # 7ILLIAMSON   h0ROPERTIES AND APPLICATIONS OF REFLECTIV E 
 This picture was taken in 1944 at TRE and was an experimental installation in one of three Fortresses based at RAF Defford at that time for radar countermeasures and bombing research being undertaken by TRE. Figure 3.6. Indicator unit type 162 [ 4].Airborne Maritime Surveillance Radar, Volume 1 3-9. 
 % AS - MEDIAN   , LOWER DECILE   AND 5 UPPER DECILE  CRITICAL FREQUENCIES  IN MEGAHERTZ. 
 The impedance measurements are made by looking into  a waveguide simulator that is terminated with dummy elements. This is equivalent  to looking at an infinite array from free space at a scan angle given by Eq. 13.21. 
 A typical multistage low-noise amplifier chip design, for example, may easily consume a year's worth of effort before a final design is realized. The cost of wafers and the processing costs in general are very high, such that low-yielding circuit designs may still result in high- cost components. Little circuit trimming can be accommodated in the MMIC ap- proach; consequently, designs must be made tolerant to processing variations or lower performance standards must be accepted for a given design. 
 Jorgensen, T. R. Shepherd, and A. 
 Again theneed forkeeping thestray capacity toaminimum isapparent. This issometimes difficult when large coupling condensers orlohg leads areinvolved. There are other coupling networks that will increase the cutoff fre- quency and yet preserve the same gain. 
 ASPECT 3EARCH IS DESIGNED TO DETECT  HEAD 
 Incertain other respects radar isdefinitely inferior totheeye. The detailed definition ofthepicture itoffers isvery much poorer than that afforded bythe eye. Even the most advanced radar equipment can on]yshow thegross outlines ofalarge object, such asaship; theeye can—if itcan seetheship atall—pick out fine details such astherails onthedeck and thenumber orcharacter oftheflags at the masthead. 
 One, track-while-scan, is to use the normal search mode with FM or multiple-PRF ranging and store the range, angle, and doppler of the reported detections in the computer. These detections are then used to form track files. The antenna scans in a normal search pattern, and a scan-to-scan correlation is made on the detections which update the track files. 
 wliilc tlic tllor~ol,ulsc tccl~riiqt~c ~tscd two or 111orc sinit~lta~icous beatiis. Tlle  clil'lcrctice in a~nplitudes in tlic several antenna positions was proportional to the angular error.  l'lic :tnglc of ar rival (in one coordinate) rnay also be determined by comparing the phase  diflerericc hetween the sigtlals frotn two separate antennas. 
 Ground deformation associated with post-mining activity at the french-german border revealed by novel insar time series method. Int. J. 
 II, chap. 11, and vol. III, chap. 
 Week Space Technol ., pp. 38–49, April 17, 1978. 29. 
 Karimova, S.; Gade, M. Improved statistics of sub-mesoscale eddies in the baltic sea retrieved from SAR imagery. Int. 
 Inthe interest ofsim- plicity the flip-flop isnot switched, being left onforthe duration ofthe slower sweep. When thefaster sweep isused, thebeam isswept entirely offthetube face and remains offuntil termination oftheflip-flop. The video amplifier illustrated has abandwidth ofabout 1Me/see, the exact value depending upon the stray capacity introduced bythe connecting circuits. 
 The feature that causes this propagation to be considered is that vertical polarization provides useful illumination down to the sea surface beyond the optical horizon. Figure 24.28 gives an example of ground-wave radar performance, parametric in fre- quency for the case in which both the radar antenna and the target are near the sea surface. These curves are for a smooth surface and use a 4A earth radius to approximate atmospheric refraction effects. 
 EWWWAREAINDEXCFM FAREAID  HTTPCLOUDSATATMOSCOLOSTATEEDU HTTPGPMGSFCNASAGOVDPRHTML o  4HE TERM  SOUNDER USUALLY ASSOCIATED WITH ACOUSTIC ECHO SOUNDING  DERIVES FROM MANY CENTURIES OF OCEANIC DEPTH  MEASUREMENTS USING LEAD LINES AND THE LIKE 4HE LOGICAL EXTENSION FROM ACOUSTIC TO ELECTROMAGNETIC METHODOLOGY IS A SMALL STEP IN COMPARISON. £n°Èä  2!$!2 (!.$"//+  )N ADDITION TO THE USUAL '02 CONSIDERATIONS  TWO SPACE 
 J. Shi et al., “Estimation of soil moisture with L-band multipolarization radar,” Proc.  IGARSS04 , vol. 
 London, 1976.. 117. Pecbles. 
 The greater the  wrap-up factor, the less the frequency band required to steer the beam over a given angle;  however, the longer it will take to fill the array and the less will be the bandwidth that the array  can support. For example, if the array antenna had an aperture of 5 m and if the wrap-up  factor were 15, it would take 0.25 JlS to fill the array. The pulse width should be long compared  to this time if distortion is not to result. 
  
 ARRAY ANTENNAS v  )%% )NT #ONF ON !NTENNAS AND 0ROPAGATION )#!0     -ARCH n !PRIL     PP n  5 .ICKEL  h3UB 
 172–197 97. D. Lynch, et al., “LPIR phase 1 review,” Hughes Aircraft Report, 1977, unclassified report. 
 such as bridges, can use the visible spectrum (TV), IR, laser, or radar. Only the last-named category will be discussed. Whether they are used against airborne or surface targets, guided missiles are intended to achieve a much higher accuracy than conventional artillery, which relies on open-loop prediction (even when optical or radar target tracking is em- ployed for fire control). 
 TRACKING RADAR  9.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 units of meters of error measured at the target location. The results show that the rms  value of angle noise sang is equal to Ro/2, where Ro is the radius-of-gyration* (taken  along the angular coordinate of interest) of the distribution of the reflecting areas of the  target.33 For example, if a target’s reflecting areas have a cos2 (pa/L)-shaped distribu - tion, where a is a variable and the target span is from +L/2 to – L/2, calculation of the  radius of gyration divided by 2 gives a value of sang of 0.19 L. Typical values of sang  on actual aircraft fall between 0.15 L and 2.0 L, depending upon the distribution of the  major reflecting areas such as engines, wing tanks, and so on. 
 QUENCY LOWER BY A FACTOR OF COS A    +ELLS COMPLEX TARGETS ARE DEFINED AS AN ASSEMBLY OF DISCRETE SCATTERING CENTERS  SIMPLE CENTERS SUCH AS FLAT PLATES  REFLEX CENTERS SUCH AS CORNER REFLECTORS  SKEWED REFLEX CENTERS SUCH AS A DIHEDRAL WITH CORNER  w n  AND STATIONARY PHASE REGIONS FOR  CREEPING WAVES  7HEN THE WAVELENGTH IS  SMALL COMPARED TO TARGE T DIMENSIONS  THESE  COMPLEX TARGET MODELS APPROXIMATE CONVENTIONAL AIRCRAFT  SHIPS  GROUND VEHICLES  AND  SOME MISSILES 4HE TARGETS CAN BE COMPOSED OF CONDUCTING AND DIELECTRIC MATERIALS !T SMALL BISTATIC ANGLES  THE COS A    FREQUENCY REDUCTION TERM HAS LITTLE EFFECT IN  +ELLS PSEUDO 
 TIME 
 Itwill beuseful todistinguish between compound targets distributed throughout avolume (rain, “window”) and those distributed over a surface (vegetation, waves). Inthis section thefirst class isconsidered, the second being deferred toSec. 3.11. 
 PROCESSING  SYSTEM SORTS THE RANGE AND CROSS 
 368 INTRODUCTlON TO RADAR SYSTEMS  55. Reynolds, J. F., and M. 
 This  is i~~iportar~t in radar applicatio~l since the receiver sensitivity will be degraded if suficient  electrons are preserit during the interpulse period to cause the stray electron-current noise to  cvcccrl I cccivcr ~lclisc.  'I'lie Iiigli-power klystron rnay also be pulsed with a grid it1 the electron gun so designed  tliat tlle grid does not intercept the  electron^.^^' Such nonintercepting gridded guns can switch  tile hearn witti low-power modulators. This technique actually uses two closely spaced and  aligned grids. 
 Theoretical calculations ofthenecessary gradients required toaccount forthe observed angelreflections wereexcessively largecompared towhatisfoundintherealatmo­ sphere.Instead, itisbelieved thattheobserved backscattering canbeexplained asrefleclions fromatmospheric turbulence associated withinhomogeneities intherefractive indexThese inhomogeneities mightbecausedbydifferences inthewatervapor,temperature, andpressure. Atlowaltitude, variations inthewater-vapor pressure (humidity) areprobably thedominant effect.Athighaltitude, thereislittlewatervapor,andchanges intemperalure havethemost effectontherefractive index. Reflections fromclear-air turbulence arethusapotential sourceofradarangelechoes. 
 since phase coherence can be maintained over a train of pulses in an amplifier- type transmitter, second-time-around clutter can also be canceled, whereas in an oscillator-type system, second-time-around clutter will be noise-modulated by the random starting phase of the oscillator tube. Amplifier chains also allow full coherence, in which the PRF, IF, and RF frequencies are all locked together; this is sometimes necessary to keep PRF harmonics out of IF doppler bands. Instabilities. 
 COMBINING CIRCUITRY WAS A RELATIVELY NEW ART 4HESE PROBLEMS WERE OVERCOME AND MONOPULSE  RADAR  WITH MOD 
 ¤ ¦¥³ µ´§ ©¨ ¨¶ ¸· ·COSQ    AND THE PHASE ADVANCE BETWEEN THE SECOND PAIR OF PULSES SECOND AND THIRD PULSE FOR  THE THREE 
 104-109, December, 1945; pt. 3, vol. 19, pp. 
 KM RESOLUTION  THEIR WIDE SWATH AND FREQUENT REVISIT INTERVALS ARE WELL SUITED TO SYNOPTIC COVERAGE OF GLOBAL 
 SIGHT TO HELP SUSTAIN NEAR 
 The decrease in water vapor pressure is approximately logarithmic, which  contributes a logarithmic decreasing term to the index of refraction.  The evaporation duct exists over the ocean, to some degree, almost all of the time. The  lieigl~t of the duct, which is usually within the range from 6 to 30 m, varies with the geographic  location. 
 Stretch Processing.  In stretch processing, the LO signal frequency is modulated  with a chirp waveform similar to that of the received signal to reduce the bandwidth  of the IF signal as described in Section 6.3. The wideband chirp waveform is typically  generated by passing a narrower bandwidth linear frequency modulation (LFM) wave - form through a frequency multiplier that increases both the operating frequency and  bandwidth of the chirp waveform. 
 An extension of the standard atmosphere to 120,000 meters was  prepared in 1947. ch26.indd   2 12/15/07   4:52:49 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 In either case, it is neces - sary to trade energy for time in order to achieve the desired search frame time. FIGURE 13.37  A spoiled transmit beam and a  cluster of four simultaneous receive beams ch13.indd   55 12/17/07   2:41:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Thus, PE models allow for a single model assess - ment in many important applications. Three such PE models are the Terrain Parabolic  Equation Model (TPEM),15 the Tropospheric Electromagnetic Parabolic Equation  Routine (TEMPER),16 and the Variable Terrain Radio Parabolic Equation (VTRPE).17 Hybrid Models.  While PE models are very attractive, they also have their disad - vantages. 
 I. Skolnik (ed.),  McGraw-Hill Book Company, New York, 1970.  3. 
 28, pp. 7-10.  32. 
 Backlash may also be reduced with conventional motors by duplicate  parallel drives with a small residual opposing torque when near zero angle rate.  Amplifier gain and filter characteristics as well as motor torque and inertia deter - mine the velocity and acceleration capability or the ability to follow the higher-order  motion of the target. It is desired that the antenna beam follow the center of the target as closely as pos - sible, which implies that the servosystem should be capable of moving the antenna  quickly. 
 J. Percival and K. A. 
 S. Pak, and R. L. 
  
 PLANE SHOWN .   2%&,%#4/2 !.4%..!3   £Ó°Ó ! PHASED ARRAY %3!  TYPE FEED COVERING THE FOCAL REGION PLANAR OR CURVED IN  SHAPE   SUCH AS THAT SHOWN IN &IGURE  B  CAN PROVIDE IMPROVED CAPABILITY )T OFFERS  TWO ENHANCEMENTS THAT EXTEND THE CAPABILITY ABOVE AND BEYOND THAT OF A MULTIPLE FEED  ARRAY WITH SWITCHED BEAMS 4HE PHASED ARRAY FED REFLECTOR CAN TRANSMIT OR RECEIVE BEAMS OVER CONTINUOUS ANGLES WITHIN THE &/6 WHEREAS THE MULTIPLE FEED ARRAY IS LIMITED TO DISCRETE BEAM POSITIONS )T ALSO PROVIDES GREATER APERTURE EFFICIENCY BECAUSE IT ALLOWS FOR ADJUSTMENT OF THE ELEMENT AMPLITUDES AND PHASES TO REDUCE SCAN LOSSES DUE TO ABERRATIONS )F WE VIEW THE REFLECTOR  AS A COLLECTOR OF PARALLEL RAYS FROM A RANGE  OF ANGLES COVERING THE &/6 AND EXAMINE THE CONVERGING RAY PATHS  &IGURE  A   IT  IS EVIDENT THAT AN APPROPRIATELY SIZED  FEED REGION CAN BE FOUND THAT INTERCEPTS MOST OF  THE ENERGY )F THE PHASED 
 It consists of a transmitter, receiver, indicator, and the necessary antennas. In princi­ ple, the CW radar may be converted into a pulse radar as shown in Fig. 4.lh hy providing a  power amplifier and a modulator to turn the amplifier on and off for the purpose of generating  pulses. 
 Furthermore, the mechanical assembly put constraints on the transportability and weight of the system. To overcome these limitations an electronically switched array would be preferable, which however faces enormous technological and cost difﬁculties associated to the large number of array elements needed. Imaging Multiple-Input Multiple Output (MIMO) radars can be used as a signiﬁcant alternative to usual mechanical SAR and full array systems. 
 G. Spiridonov, Radiolokatsia Poverchnosti Zemli   Iz-Kosmoca  (Radar Observation of the Earth from Space) , Leningrad: Hydrometeoizdat,  1990. (In Russian.) 161. 
 TRIP DELAY  NOT DISTANCE !T THE ACCURACY REQUIRED OF A SPACE 
 Thegainofaparaboloid withliD=0.25(f=focaldistance,D=antenna. KAljAK ANTliNN AS 245  diameter) is reduced to 80 percent of its rnaximum value when the beam is scanned L-3  beamwidths off axis. A paraboloid wit11 f/V = 0.50 can be scanned k6.5 beamswidths off axis  before the gain is reduced to 80 percent of maxitnum (Ref. 
 When optical proces-;ing is employed, the  linear FM. or chirp. pulse-compression waveform readily lends itself to the same type or  processing as described for the cross-range signal.7 The form or the linea· FM signal in the  range dimension is similar to the form or the signal in the cross-range dim~nsion. 
 AES-7. pp. lot) 110, Jan. 
 ETERS ARE WELL 
 Haralick, R. K. Moore, and A. 
 WIDTH DISCRIMINATION TECHNIQUE CAN HELP IN REJECTING CHAFF IN FACT  ECHO RETURNS FROM CHAFF CORRIDORS ARE MUCH WIDER THAN THE TRANSMITTED PULSE (OWEVER  IF A TARGET IS WITHIN THE CHAFF CORRIDOR THE PULSE WIDTH DISCRIMINATOR MIGHT ALSO ELIMINATE THE TARGET #OHERENT 0ROCESSING  4HE MOST EFFECTIVE ANTI 
 1958.  59. Webster. 
  
 BISTATIC RADAR  23.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 analogous to that for a monostatic radar. The equation is then solved for the bistatic  maximum range product , (RT RR)max. Next, an equivalent monostatic maximum range,   (RM)max, is defined omitting the max subscript for convenience, as shown here:  RM = (RT RR)1/2 (23.1) This equivalent monostatic maximum range, also known as the geometric mean  range,  represents performance of the bistatic radar when transmitter and receiver are  co-located; i.e., when L = 0. 
 ING DEPARTMENT ARE NOT ALWAYS THE SAME )T IS APPRECIATED  HOWEVER  THAT SOMETIMES THE MARKETING MANAGERS OPINION HAS TO PREVAIL IF THE COMPANY IS TO REMAIN IN BUSINESS ! NUMBER OF DIFFERENT 2& POWER SOURCES HAVE BEEN CONSIDERED THAT  AT ONE TIME OR  OTHER  HAVE BEEN EMPLOYED IN RADAR .OT ALL MIGHT BE POPULAR OR DESIRED AT SOME PARTIC 
 0.3TABLE 19.2  Drop Size Distributions at Different Precipitation Rates51 TABLE 19.3  Attenuation in Decibels per Kilometer for Different Rates of Rain Precipitation at a  Temperature of 18 °C Using the Drop-size Distributions in Table 19.251 Precipitation  Rate R, mm/hWavelength l, cm l = 0.3l = 0.4l = 0.5l = 0.6l = 1.0l = 1.25l = 3.0l = 3.2l = 10      0.25   0.305    0.230   0.160   0.106   0.037    0.0215 0.00224 0.0019 0.0000997   1.25   1.15    0.929   0.720   0.549   0.228    0.136 0.0161 0.0117 0.000416   2.5   1.98    1.66   1.34   1.08   0.492    0.298 0.0388 0.0317 0.000785  12.5   6.72    6.04   5.36   4.72   2.73    1.77 0.285 0.238 0.00364  25.0 11.3 10.4   9.49   8.59   5.47    3.72 0.656 0.555 0.00728  50 19.2 17.9 16.6 15.3 10.7    7.67 1.46 1.26 0.0149 100 33.3 31.1 29.0 27.0 20.0 15.3 3.24 2.80 0.0311 150 46.0 43.7 40.5 37.9 28.8 22.8 4.97 4.39 0.0481 ch19.indd   10 12/20/07   5:37:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 
 RACY OF THE DISPLAYED RADAR IMAGE IN HAVING TO COMPENSATE FOR A SHIPS HEADING WITH COMPASS INPUT )N PARTICULAR  TARGET TRACKING IS PERFORMED FROM A STABLE AND STATIC PLAT 
 DETECTION HARDWARE &IGURE  ILLUSTRATES TWO DIGITAL SIGNAL 
 60,  pp. 557-563, May, 1972.  68. 
 Y . I. Abramovich, V . 
 99. Ruze, J.: The Effect of Aperture Errors on the Antenna Radiation Pattern, Slippl. a1 Nuotto cinrenro,  vol. 
 BAND IN (( 
 Radar  Meteorol ., AMS, Tallahassee, 1989, pp. 619–622. 75. 
 But that separation is small compared with the target location of thousands of kilometers,1'2 and the radar operates with monostatic characteris- tics. When two or more receive sites with common spatial coverage are employed and target data from each site is combined at a central location, the system is called a multistatic radar. Thinned, random, distorted, and distributed arrays,3"6 interferometric radars,7"10 the radio camera,11'12 and the multistatic measurement system13'14 are sometimes considered a subset of multistatic radars. 
 The three traces in these charts  are the 80, 50, and 20 percentile levels of the signals collected over aspect angle “win - dows” 2 ° wide. The patterns are not symmetrical, especially at the higher frequency.  Note that the RCS can exceed 1 mi2 (64.1 dBsm).FIGURE 14.11  Measured RCS pattern of a B-26 bomber at a frequency of 3 GHz19 ch14.indd   13 12/17/07   2:46:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 This very simple method issatisfactory provided little ornointerference isencoun- tered. Aninterfering pulse will, however, cause Ttotake apotential corresponding toitstime ofappearance. This effect can bereduced by filtering sothat nosingle pulse can cause any very great change, but this filtering may cause troublesome phase lags inthe desired output. 
 REAL 
 THRESHOLD SIGNALs—Lawson and Uhlenbeck 25. THEORY OFSERvoiuEcIIANIsivs-James, Nichols, and Phillips 26. RADAR SCANNERS AND RADOXES—CUdrJ, Karelitz, and Turner 27. 
 ING THE USE OF '02 4HESE ARE THE USE FIRST OF THE EQUIPMENT AS A DELIBERATE RADIO FREQUENCY RADIATOR AND SECOND AS AN EQUIPMENT THAT MUST SATISFY THE %-# REQUIRE 
 ERS IN A PHASE SCANNED ARRAY MUST BE CHANGED ON AN INTRA 
 Repeat Steps 2 and 3 until the centroid locations converge to a ﬁxed value. 2.3. K-SVD K-SVD is a dictionary learning algorithm that is used for training overcomplete dictionaries for sparse representations of signals [ 28,29]. 
 Zadeh, L.A., and J. R. Ragazzini: Optimum Filters for the Detection of Signals in Noise, Proc. 
 SCALE EXPERIMENTAL MEASUREMENTS CAN BE MADE IN SOME CIRCUM 
 RADAR CROSS SECTION  14.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 target aspect angle as seen from the radar. Some are dominant scattering mechanisms  whereas others are weak. Not all are significant on other kinds of platforms, such as  warships or military ground vehicles. 
 REPEAT MISSION  IN SUPPORT OF OPERATIONAL REQUIREMENTS FOR THE 53 .AVY '&/ REPRESENTS THE CURRENT STATE 
 STAGE SOLID 
 ALLY OMNIDIRECTIONAL IN AZIMUTH BUT CAN HAVE A RESTRICTED ELEVATION BEAMWIDTH AND TYPICALLY HAVE AN OVERALL GAIN OF ABOUT  D" 0RIME POWER CONSUMPTION IN AVERAGE TRAFFIC CAN BE LESS THAN  WATT 4HE MODULATION ON THE RESPONSE SIGNAL OF A RACON PAINTS A -ORSE CODE IMAGE ON THE  RADAR DISPLAY 4HE CODE IDENTIFIES A PARTICULAR !TO. AND APPEARS IN THE RADIAL DIRECTION  CONVENTIONALLY COMMENCING WITH A DASH 4HIS DASH STARTS A SHORT DISTANCE BEYOND THE ACTUAL POSITION OF THE !TO. BECAUSE OF INHERENT DELAYS IN THE RESPONSE TIME OF THE RACON (OWEVER  DELAYS GIVING AN ERROR OF LESS THAN  METERS ARE READILY ACHIEVABLE )N GOOD CONDITIONS  THE !TO. PRIMARY RADAR IMAGE WILL BE DISPLAYED ON THE RADAR SCREEN  HELPED IF A PASSIVE RADAR REFLECTOR IS ALSO A PART OF THE !TO. 2ACONS HAVE TO INCLUDE MUTING PERIODS TO ALLOW SHIP RADARS TO LOOK FOR SMALL TARGETS IN THE VICINITY OF THE RACON IDENTIFIER 4HE LONG 
 , .. , . t  · .. 
 An estimate of the target's angular position may be made by locating the center of the  group of tr pulses.s6 This operation is called beunr splitting. The moving-window detector has  no prior knowledge of the target beginning. It must be sufficiently sensitive to quickly detect a  region of increased density of Is, yet it must not be so sensitive that it initiates false alarms due  to noise. 
 For a surveillance radar, this increased power is  collected for a proportionally shorter time, since the radar must search more cells in  the same time because of the narrower antenna beamwidth. With sidelobe jamming, the received jamming power is proportional to the sidelobe  antenna gain, ( Gsl) resulting in a net increase in signal-to-jamming power ratio by  the factor GtGsl−1. As with surveillance radars, sidelobe noise jamming and deception  can be further attenuated by the use of SLC in conjunction with SLB, as described in  Section 24.6. 
 It was observed that with a large enough duct more than one mode can he propagated  and there can be more than one antenna height suitable for low-loss propagation. For  example,3 7 one set of X-band data showed the minimum attenuation to occur with an antenna  height of 2 m. Increasing the antenna height increased the loss to a maximum at ahout 10 m  height. 
 Amphibious R. Receiving M. Mobile (ground) S. 
 Anonymous: News item in Aviation Week and Space Technology, vol. 109, no. 13, p. 
      $*  
            
 Ó°ÇÓ  2!$!2 (!.$"//+  VALUES SHOWN IN THESE EQUATIONS CAN BE REPLACED BY THE RMS PULSE 
 4ARGET )NDICATION -4)  3!2  7ITH RESPECT TO CON 
 STATE FILTERING AND SMOOTHING PERFORMANCE v  )%%% 4RANS !EROSPACE AND %LECTRONIC 3YSTEMS  VOL !%3 
  
 PONENTS  IN THEIR OPERATIONAL CONFIGURATION  BE TESTED FOR PHASE STABILITY IN THE VIBRATION ENVIRONMENT IN WHICH THEY WILL BE USED &ACT  4HE BASIC -4) CONCEPT DOES NOT REQUIRE SUFFICIENT TIME 
 9.1 ). Let F 1, GI be  the noise figure and available gain, respectively, of the first network, and F 2, G2 be similar  parameters for the second network. The problem is to find F O, the overall noise-figure of the  two circuits in cascade. 
 As a step forward, we propose a simulation method for oceanic shear-wave-generated eddies. The Burgers-Rott vortex model is used to specify the surface current ﬁeld of the simulated eddies. Images are then simulated for a range of different radar frequencies, radar look directions, wind speeds, and wind directions. 
 This phase difference may be used as a measure of the elapsed time. When the two  signals slip in phase by 1 cycle, the measurement of phase, and hence range, becomes  ambiguous.  The two-frequency CW radar is essentially a single-target radar since only one phase  difference can be measured at a time. 
 (a) reference image; ( b) mission image; ( c) two-color multiview (2CMV) image. In both images, there is an airplane visibly parked next to an airport building near the bottom center. In the second image ( b), the airplane seems rotated by a small degree. 
 When the duration of the transmitted radar signal, whether CW or a repetitive train  of N identical pulses, is comparable with or greater than the reciprocal of anticipated  target doppler shifts, the difference between a conventional white-noise matched fil - ter (or coherent integrator) and a filter optimized to reject the accompanying clutter  becomes significant. The characteristics of the clutter are characterized by the covari - ance matrix ΦC of the N clutter returns. If the power spectrum of the clutter is denoted FIGURE 2.21  MTI improvement factor as a function of the rms velocity spread of clutter for   a three-pulse binomial-weight canceler ch02.indd   26 12/20/07   1:44:17 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 If the surface has an underlying curvature, the number of illuminated crests sat- isfying the resonance criterion may be limited by the length of the essentially flat region; otherwise it is limited by the radar resolution. The theoretical expression for the scattering coefficient is48 o-^o = sk^2 CQS4 eia^|2W(2£ Sin 05o) (12.7) where p,q = polarization indices (H or V) k = 2ir/\ (the radar wavenumber) GLHH = R1 (Fresnel reflection coefficient for horizontal polarization) sin2 6 - €r (1 + sin 2 9)OLVV = (er-l) —— [er cos 6 + (er - sin 2 0)1/2]2 where er is the relative permittivity e' - ye" and OLVH = aHV = O. W(2 A: sin 6, O) is the normalized roughness spectrum (the Fourier transform of the surface autocorrelation function). 
 BLANKER THAT REMOVES THESE REPORTS FROM THE FINAL OUTPUT )N THE CASE OF THE TRACKER 
 ASTIA ATI 46616.  60. Kaiser. 
 ORDER REQUIREMENT RESULTS FROM THE NEED FOR   ! "  #   ! "  #    " $   " $  &  "          "$ "    "   &$       "   #"  "  ""         "         "         "         "         "         "    
 Jollnson. R. C.: The Geodesic Lttnebt~rg Lens. 
 The largest isolations are obtained with two antennas-one for transmission, the other for  reception-physically separated from one another. Isolations of the order of 80 dB or more  are possible with high-gain antennas. The more directive the antenna beam and the greater the  spacing between antennas, the greater will be the· isolation. 
 Since the 1980s, the power output  capability among various solid-state technologies has increased to the point where they  are actively pursued as replacements for some vacuum electronics in radar transmitters;  this is not, however, a universally attractive solution. The transition from high-power  klystrons, traveling wave tubes (TWTs), crossed-field amplifiers (CFAs), and magne - trons, to solid-state electronics has actually been very gradual because the power output  of individual solid-state devices is quite limited compared to typical radar requirements.  Nevertheless, transmitter designers have learned that the required higher power levels  for radar transmitters can be achieved with a solid-state technology because transis - tors and transistor amplifier modules can be readily combined in parallel to achieve  a composite higher equivalent power output. 
 SNR is the ratio of rms signal amplitude to rms  A/D converter noise power. For an ideal A/D converter, the only error is due to quan - tization. Provided that the input signal is sufficiently large relative to the quantization  size and uncorrelated to the sampling signal, the quantization error is essentially ran - dom and is assumed to be white. 
 BY 
 availability ofcolorallowsanintensity-modulated CRT,whichisnormally of limiteddynamic range,todisplaytargetamplitude information bycolorcodingthetargetblip according tothemagnitude ofthetargetcrosssection. Studiesshowthatthreeorperhaps fourcolorsistheoptimum number forcolordisplayapplication.s7,58Aparticular four-color displaytestedforair-traffic-control radarutilizedyellowtopresenttheaircraftdatablocks, gleenforthearea-sector maplines,redfornavigation aids,andorange forshowing precipitation.61 Thetricolorshadow-mask cathode-ray tubecommonly usedforcolortelevision hasa phosphor screenthatconsists ofaseriesofthreecolordots.Although itmaybewellsuited forcommercial TV.itisnotalwaysagooddisplayforradarsinceitsresolution islimited bythesizeandspacingofthedots.Another colorCRTofinteresttoradaristhepenetration color(liheusingamulti-layer screen.Thecoloriscontrolled bytheanodevoltagewhich determines thedepthofpenetration oftheelectron beamintoaseriesofphosphor layers. Varying theanodevoltagevariesthedepthofpenetration andtheparticular phosphor layer thatisexcited.Typically, thedifference between penetration ofthelayersisabout4kVper layer.·,nAsingle-electron-gun. 
 Vol. AES-IO. pp. 
 CAL MULTIPATH INTERFERENCE PATTERN 4HIS IS EASILY ACCOMPLISHED BY MOUNTING THE RADAR ANTENNAS ON CARRIAGES THAT CAN BE RAISED OR LOWERED ALONG RAILS INSTALLED ON THE SIDE OF A BUILDING OR A TOWER 4HE IDEAL GROUND PLANE OFFERS A THEORETICAL SENSITIVITY ENHANCEMENT OF  D" OVER  IDENTICAL MEASUREMENTS MADE IN FREE SPACE 4HE ACTUAL ENHANCEMENT IS USUALLY LESS THAN THIS  PRIMARILY BECAUSE OF THE DIRECTIVITY OF THE ANTENNAS AND IMPERFECTIONS IN THE GROUND PLANE !NTENNA DIRECTIVITY PRECLUDES THE TARGET EVER BEING SQUARELY ALIGNED ON THE BORESIGHTS OF BOTH THE REAL ANTENNA AND ITS IMAGE IN THE GROUND PLANE AT THE SAME TIME  AND THE REFLECTION COEFFICIENT OF TYPICAL GROUND PLANES VARIES FROM  TO AS LOW AS  OR LESS &OR ALL EXCEPT VERY HIGH AND VERY LOW FREQUENCIES MILLIMETER WAVE 
 (i.. J. J. 
 At'-4. pp 3x5 302.  July, 1956. 
 #&!2  WHERE ALL REFERENCE SAMPLES ARE EQUALLY WEIGHTED )F MORE THAN ONE  NOISE ANDOR CLUTTER AMPLITUDE IS USED TO UPDATE THE CLUTTER MAP CONTENT ON EACH SCAN   THE VALUE OF  ,EFF SHOULD BE INCREASED PROPORTIONALLY )T SHOULD ALSO BE NOTED THAT MOST  RADARS BASE THEIR TARGET DETECTION ON MULTIPLE HITS USING SOME  FORM OF VIDEO INTEGRA 
 Instead, the frequencyof the incoming signals (echoes) is mixed (heterodyned) with that of a localoscillator in a crystal mixer to produce a difference frequency called the intermediate frequency. This intermediate frequency is low enough to be ampliﬁed in suitable intermediate frequency  ampliﬁer stages in the receiver. Pulse Repetition Frequency The Pulse Repetition Frequency (PRF), sometimes referred to as Pulse RepetitionRate(PRR)isthenumberofpulsestransmittedpersecond.Somecharacteristic values may be 600, 1000, 1500, 2200 and 3000 pulses persecond. 
 1290- 1296, July, 1960.  47. Knott, E. 
 (f'lii~sctl-array radars and sorne surveillarlce radars, however, [night use the  rnorlopulse prirlciplc to extract an ar~gle ~neasurement on the basis of a single pulse.) I11  practice. the two radars utilize essentially the same number of pulses to obtain an error signal  if the servo tracking bandwidths and pulse repetition frequencies are the same. The monopulse  radar first makes its angle measurement and then integrates a number of pulses to obtain  the required signal-to-noise ratio and to smooth the error. 
 Feasible satellite altitudes are  limited below by the prevailing atmospheric density. The final column of the table  lists the altitude-velocity product hVSC corresponding to each entry. This product is a  scaling factor that characterizes the range-doppler space confronting an SBR intended  to be deployed in that environment. 
 In that  same month the detection of an aircraft was carried out, using 6-MHz communication equip-  ment, by observing tlie beats between the echo signal and the directly received signal (wave  interference). The technique was similar to the first United States radar-detection experiments.  The transmitter and receiver were separated by about 5.5 miles. 
 If the antenna is below a duct, it is improbable that targets above the duct will be detected. Ininstances of extremely low-level ducts when the antenna is above the duct,surface targets lying below the duct may not be detected. The latter situationdoes not occur very often. 
 7HILE 
 H.: Theory of Absorbers in Scattering, Trans. IEEE, vol. AP·l I. 
 OF 
 The description, method ofoperation, and characteristics ofthis type of magnetron arethe subject ofthe first part ofthis chapter. Asasource ofhigh-power microwaves the multicavity magnetron represents avery great advance over both theconventional space-charge and the velocity-modulated orklystron-tube types. Afew numerical comparisons will emphasize this superiority. 
 Operational disadvantages put  forward by some navigators are that the CRT is rather  bulky if the range is to be effective, and the presentation  is not so ‘pictorial’ as that given by, say, a PPI display.  British and American scientists have made valuable  contributions to the technique and practice of beaconry,  and an interesting American development is the blind-  approach system known as SCS-51, which a usually  around 100 Mcs.  In most commercial forms of this equsinent there is  a ‘localizer,’ a ‘glide-path,’ and three marker beacons. 
 These magnetrons generate peak powers from 3 to 75 kW and have relatively low  average powers of a few watts to a few tens of watts. An example of a magnetron for  a civil marine radar is the MG5241 manufactured by EEY of Chelmsford, England.  It is an 18 cavity X-band magnetron that operates at a fixed frequency within the  band from 9380 to 9440 MHz with a peak power of 12.5 kW and an efficiency of  43%. 
 Thedifference frequency isequaltothedoppler frequencYfd' Forstationary targets thedoppler frequency shiftldwillbezero;henceVdiffwillnotvarywithtimeandmaytakeon anyconstant valuefrom1-.'14to-/14,including zero.However, whenthetargetisinmotion relative totheradar.!d hasavalueotherthanzeroandthevoltagecorresponding tothe difference frequency fromthemixer[Eq.(4.3)]willbeafunction oftime. Anexample oftheoutputfromthemixerwhenthedoppler frequencY!d islargecompared withthereciprocal ofthepulsewidthisshowninFig.4.2b.Thedoppler signalmaybereadily discerned fromtheinformation contained inasinglepulse.If,ontheotherhand,fd issmall compared withthereciprocal ofthepulseduration, thepulseswillbemodulated withan amplitude givenbyEq.(4.3)(Fig.4.2c)andmanypulseswillbeneededtoextractthedoppler information. Thecaseillustrated inFig.4.2cismoretypicalofaircraft-detection radar.while thewaveform ofFig.4.2bmightbemoreapplicable toaradarwhoseprimary function isthe detection ofextraterrestrial targetssuchasballistic missilesorsatellites. 
 Each will be discussed briefly.  The rtonlinear-FM waveform with constant-amplitude time envelope provides a com-  pressed waveform with low time-sidelobes at the output of the receiver matched-filter without  the 1- to 2-dB penalty obtained with the linear-FM waveform and mismatched filter. '6*24.32  The nonlinear variation of frequency with time has the same effect as amplitude-weighting the  transmitted-signal spectrum, while maintaining the rectangular pulse-shape desired for  efficient transmitter operation. 
 ABLE MOISTURE NEAR THE TOP OF THE LAYER 4HIS IN TURN CREATES A POSITIVE  . GRADIENT OR  SUBREFRACTIVE STRATUM ALOFT 4HIS LAYER MAY RETAIN ITS SUBREFRACTIVE NATURE INTO THE EARLY EVENING HOURS  ESPECIALLY IF A RADIATION INVERSION DEVELOPS  TRAPPING THE WATER VAPOR BETWEEN TWO STABLE LAYERS &OR AREAS WITH SURFACE TEMPERATURES BETWEEN  AND  #ELSIUS AND RELATIVE  HUMIDITIES ABOVE  IE  THE WESTERN -EDITERRANEAN  2ED 3EA  )NDONESIAN 3OUTHWEST 0ACIFIC   SURFACE 
 Ground-based radars used for severe storm research or warning will normally use S-band («3 GHz) or C-band («5.5 GHz) transmitters. Air- borne storm avoidance radars will use either C-band or X-band («10 GHz) transmitters. Al0 beam width is commonly used for longer-range radars. 
 The second row of plots shows the relative voltage of the maximum pulse matched filter (MF) output as a function of range-ambiguous target return  within the IPP. The third row of plots shows the output in terms of relative power .1No RG Overlap: τt = τg = τs ; τb = 0 ; IPP = 5τg 0Transmit Pulse 0 1 2 3 4 5 1 0.5 0MF Output “Voltage” 0 1 2 3 4 5 0.51 0MF Output “Power” 0 1 2 Time Normalized by Range-Gate Duration3 4 5150% RG Overlap: τt = τg = 2τs ; τb = 0 ; IPP = 5τg 0Transmit Pulse 0 0.5 1.5 2.5 3.5 4.5 1 2 3 4 5 0.5 1.5 2.5 3.5 4.51 0.5 0MF Output “Voltage ” 0 1 2 3 4 5 0.5 1.5 2.5 3.5 4.50.51 0MF Output “Power ” 0 1 2 Time Normalized by Range-Gate Duration3 4 5 ch04.indd   42 12/20/07   4:53:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 * *&(   *    !#* (  !  *!%   '+(  , 
 VIEW THAT MAY BE  MOVED BY PEDESTAL DRIVE TO  CENTER ON A MULTITAR GET EVENT OR FOLLOW AN EVENT PROGRESS 
 TO 
 II IF frequency. Mc/s H2S/ASV.S in 24 V machines TR 3190 TR 3160 13.5 ASV.X, AI.X in 24 V machines TR 3196 TR 3505 45ASV.X, AI.X in 12 V machines TR 3197 TR 3507 45 Figure 6.2. Lucero Mk. 
 WAVE EMISSION AND BACKSCATTERING v )%%% 4RANS  VOL '% 
 (Courtesy of Ingalls Shipbuilding Division of Litton.) . would be a logical choice. If a waveguide phase shifter is used, an open-ended waveguide or a slot might be convenient. 
 BASED  RADAR  AN EXTENDED INTERACTION KLYSTRON  4HE KLYSTRON IS DRIVEN BY  M7 SIGNALS  FROM A SOLID 
 12.22 Independent Samples Required for  Measurement Accuracy  ...................................  12.23  Near-Vertical Problem  .......................................  12.23 Ground and Helicopter Scatterometers and  Spectrometers  ................................................. 
 With the clutter at dc the in-phase (/) and quadrature (Q) chan- nel amplitude and phase-balance requirements are eased, as the images resulting from unbalance also fall near dc and can be filtered out along with the main-beam clutter. Transmit Pulse Suppressor. Further attenuation of transmitter leakage is provided by the transmit pulse suppressor in the receiver IF, which is a gating device. 
 .#*( (% "%*( ( %&)   #)"+ !( (% /"   '-   '  ( &)'52%   &OUR 
 There is a lack of published methods for efﬁcient generation of 2CMV products from SAR images, which serves as another motivating factor for this work. The paper is organized in four sections. Following this introduction, Section 2gives a brief background on the ﬁltering, unsupervised feature learning, and optical ﬂow techniques that were used and describes the stages of the proposed framework. 
 -   * $ +RAUS  !NTENNAS  ND %D  .EW 9ORK -C'RAW 
 HANDED CIRCULARLY .   '2/5.$ 0%.%42!4).' 2!$!2   Ó£°££ POLARIZED ,(#0  WAVE FROM A PLANAR SURFACE  BUT SOME PROPORTION OF 2(#0 WILL BE  REFLECTED FROM A THIN PIPE OR WIRE 4HIS ENABLES THE GROUND 
    
 Ametalspace-frame radomemightconsistofindividual triangular pandsmade.:upofa frameofaluminum extrusions encapsulating alow-loss dielectric reinforced plasticslaminate membrane. Insteadoftheuniform panelsizesofFig.7.29,thespace-frame radomecanusea quasi-random selection ofdifferent panelsizestominimize periodic errorsintheaperture distribution whichcangiverisetospurious sidelobes. Italsotendstomakethe~adome insensitive topolarization. 
 QUENCY MODULATION WAVEFORM IS USEFUL IN A TRACKING SYSTEM WHERE RANGE AND DOPPLER FREQUENCY ARE APPROXIMATELY KNOWN  AND THE TARGET DOPPLER SHIFT CAN BE COMPENSATED IN THE MATCHED FILTER 4HE NONSYMMETRICAL  .,&- WAVEFORM IS USED IN THE --2 SYSTEM   FOR EXAMPLE  WHICH DETECTS AND TRACKS ORDNANCE SUCH AS MORTARS  ARTILLERY  AND ROCKETS 4O ACHIEVE A n 
 DOMAIN RADAR  THE DISPERSIVE PROPERTIES OF THE ANTENNA USED MUST BE COMPENSATED BY SUITABLE POST 
 whose average gain is 6, the improvement factor is  f/ J/ ,l 4 a2f/ lie"'--·--=--~-= ---8rr4a: 128n4<r! 2n4f04 (4.26)  !\ plot of Fq. (4.26) for the double canceler is shown in Fig. 4.30. 
 Expressed in terms of power ratio, the latter conventiondeﬁnes beam width as the angular width between QUARTER-POWERPOINTS. The half-power ratio is the most frequently used convention. Which convention has been used in stating the beam width may be identiﬁed fromthe decibel (dB) ﬁgure normally included with the speciﬁcations of a radarset. 
 Alargedifference infrequency between thetwotransmitted signalsimproves theaccuracy oftherangemeasurement sincelargeI1fmeansaproportionately largechangeinAcPfora givenrange.However, thereisalimittothevalueof4f,since11<jJcannotbegreaterthan2n radiansiftherangeistoremainunambiguous. Themaximum unambiguous rangeRunambis, ) c Runamb=2I1f (3.23) Therefore I1fmustbelessthanc/2Runllmb.Note thatwhenI1fisreplaced bythepulserepetition rate,Eq.(3.39)givesthemaximum unambiguous rangeofapulseradar. Aqualitative explanation oftheoperation ofthetwo-frequency radarmaybehadby considering bothcarrierfrequencies to'beinphaseatzerorange.Astheyprogress outward fromtheradar,therelative phasebetween thetwoincreases because oftheirdifference in frequency. 
 For example, a well-designed vertical-polarization antenna may also radiate small amounts of the orthogonal horizontal polarization in some directions (usually off the main-beam axis). Similarly, an antenna designed for RHCP many also radiate some LHCP, which is mathematically orthogonal to RHCP. The desired polar- ization is referred to as the main polarization (COPOL), while the undesired or- thogonal polarization is called cross polarization (CROSSPOL). 
 LEVEL TRACKING IN  SATELLITE ALTIMETRY v *OURNAL OF !TMOSPHERIC AND /CEANIC 4ECHNOLOGY   VOL   PP n    7 * * #APUTI  h3TRETCH A TIME 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 depicts the presence of the target as well as of the jamming. It has been demonstrated  that Monte Carlo simulation is in close agreement with CRLB analysis. 
 Acquisition Date (yyyy /mm /dd) Normal Baseline (m) T emporal Baseline (Days) 1 2014 /06/17 −71.50 198 2 2014 /08/22 −137.97 132 3 2014 /09/13 −286.33 110 4 2014 /10/05 −110.85 88 5 2014 /10/27 −249.06 66 6 2014 /11/18 −74.56 44 7 2015 /01/01 0 0 8 2015 /02/14 −133.14 44 9 2015 /03/08 −106.99 66 10 2015 /05/13 −271.51 132 11 2015 /06/26 −122.85 176 12 2015 /08/09 −149.22 220 13 2015 /08/31 −65.63 242 14 2015 /09/22 −253.29 264 15 2015 /10/14 −159.34 286 16 2015 /11/05 −233.83 308 17 2015 /11/27 −11.87 330 237. Sensors 2019 ,19, 3073 Figure 5. Temporal and perpendicular baselines of the available pairs. 
 Tuner life: Because of cost and size tradeoffs, tube life may be limited by the finite fatigue life of the bellows required to allow actuating tuners inside the vacuum. Tuners that operate outside the vacuum must still have adequate gear and bearing design if they are not to limit tube life; in particular, backlash may be a limit. 4.3 AMPLIFIER CHAIN TRANSMITTERS It was the limitations of magnetrons that eventually pushed radars to use ampli- fier chain transmitters, which are more capable but also more complex. 
 The sand may be piled up at the center (origin) to as narrow  a pile as one would like, but its height can be no greater than a fixed amount (2£)2• If the sand  in the center is in too narrow a pile, the sand which remains might find itself in one or more  additional piles, perhaps as big as the one at the center.  The optimum waveform is one which has the desired ambiguity diagram for a given  amount of" sand" (energy). The usual pulse radar or the usual CW radar, as we shall see, does  not result in an ideal' diagram. 
 25. Barrick. D. 
 U .. and II. N. 
 (eds.): "Electronic instruments," MIT  Radiation Laboratory Series, vol. 21, pp. 383-386, McGraw-Hill Book Company, New York, 1948. 
 Harper, “A numerical representation of CCIR Report 322 high frequency  (3-30 Mcs) atmospheric radio noise data,” Nat. Bur. Stand. 
 Within the digital signal processor, detection  thresholds for each of the filters within the bank are calculated adaptively, aiming at  providing optimum control of false alarms while maximizing clutter suppression and  target detection. Manual control of the thresholds is also provided to be compliant  with IMO requirements. Modern, fully solid-state radars need little analog circuitry within their designs;  they operate on low voltages and have no time-lifed components such as magne - trons. 
 This calibration accounts for bias in  azimuth and elevation, mislevel, skew, droop, and nonorthogonality. Tracking a visible satel­ lite with the radar permits the position of the RF axis relative to the mechanical (optical) axis  to be determined. The difference between the position measured by the optics and that . 
 We can also describe the scattering using the Mueller matrix that is related to the  Stokes matrix. The reader is referred to the literature for further descriptions of the  Mueller matrix.162,165 ch16.indd   50 12/19/07   4:56:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 (Ina sidelooking SARthecross-range resolution isalsocalledthe,along-track orazimuth resolution. ) Thelimitonresolution duetooperation inthefarfieldcanbeovercome bycorrecting the received signalforthecurvature ofthespherical wavefront experienced whenthetargetis withintheFresnelregionofthesynthetic array.Ateach"element" ofthesynthetic array antennaaphasecorrection At/J=2nx2/A.Risapplied,wherexisthedistance fromthecenterof thesynthetic aperture. Notethatadifferent correction mustbeappliedforeachrangeR.When thiscorrection isappliedateachelementofthesynthetic array,theantenna issaidtobe focusedatadistance Randallthereceived echosi'gnalsfromatargetatthatrangearein phase.Theangularresolution whentheantennaisfocusedintheFresnelregionisequivalent tothatinthefarfield.Hence,the cross-range resolution ofthefocusedsynthetic aperture using Eq.(14.4)with L~=RA.IDis D <5cr=RO,="2 (14.6) Focused SARTheresolution ofthefocusedSARisindependent oftherangeandthewavelength, and depends solelyonthedimension Doftherealantenna. 
 87. W. A. 
 HOLE CONNECTIONS  TO GROUND 0HOTOGRAPH COURTESY OF  2AYTHEON #OMPANY  . 
 Z. Peebles, Jr., “Signal Processor and accuracy of three-beam monopulse tracking radar,” IEEE  Trans ., vol. AES-5, pp. 
 27.2 FACTORS AFFECTING RESOLUTION OF A RADAR SYSTEM In the following paragraphs a brief comparison of the conventional antenna, the unfocused synthetic antenna, and the focused antenna is given.3'4 The language of synthetic apertures is used, and a comparison of the resolution capability for three cases is given. A more sophisticated derivation of simultaneous resolution in range and azimuth will be given later in this chapter. Three cases are compared for their azimuth resolution capability: (1) the con- ventional technique, in which azimuth resolution depends upon the width of the radiated beam; (2) the unfocused synthetic antenna technique, in which the syn- thetic antenna length is made as long as the unfocused technique permits; and (3) the focused synthetic antenna technique, in which the synthetic antenna length is made equal to the linear width of the radiated beam at each range. 
 SOURCE TARGET 4HE RESULTANT IS   \\\\EK o$ 3     
 It has also been called externally coherent, which is a more  descriptive name. The noncoherent MTI radar does not require an internal coherent reference >I  signal or a phase detector as does the coherent form of MTI. Amplitude limiting cannot be  TR Power  oscillator  LO  To cancellation circuits Modulator  Figure 4.33 Block diagram of a noncoherent MTI radar. 
 The other spurious products of a mixer generally become more serious if the ratio  of input to output frequencies of the downconverter is less than 10. The spurious- effects chart (Figure 6.2) shows that there are certain choices of frequency ratio that  provide spurious-free frequency bands, approximately 10% of the intermediate fre - quency in width. By the use of a high first IF, one can eliminate the image problem  and provide a wide tuning band free of spurious effects. 
 #/5.4%2-%!352%3   Ó{°Ó£ SIGNALS ANDOR TO EMPHASIZE THE DESIRED SIGNAL OR SIGNALS IN THE SUMMING NETWORK  OUTPUT /UTPUT SIGNAL  : IS ENVELOPE 
 September, 1963.  96. Tischer, F. 
 ING AND 2 FOR RECEDING 4HE CURVES PLOT RECEIVED POWER VERSUS NORMAL 
 H. Cantrell, G. V . 
  AND  2!$!23!4 %ARTH 
 Although  the effectiveness of this procedure has always been somewhat controversial, there  is no question that oil can produce a slick of smooth water at relatively low wind  speeds. In fact, biological oils, produced by bacteria, algae, and plankton, can be  found everywhere on the world’s oceans and form natural slicks in those regions  that combine the greatest oil concentration with the lowest wind speeds, e.g., close  to continental shorelines.80 Man-made contaminants can, of course, have the same  effect. A layer of oil only one molecule thick will significantly affect the ability of  the surface to support wave motions, but this layer must be continuous. 
 Irregular (pseudorandom) jumping of the frequency can be obtained by varying the modulator PRF or by vary- ing the motor speed rapidly. First-order tracking information for the receiver lo- cal oscillator (LO) is obtained from anMAGNETICCOUPLING TUNINGDISK ANODESTRUCTURE FIG. 4.3 Magnetron rotary tuner. 
 MENT  INSTRUMENTS  THEIR PHENOMENAL ACCURACY AND PRECISION REQUIRES ELEGANT MICRO 
 Dax, P. R.: Accurate Tracking of Low Elevation Targets Over the Sea with a Monopulse Radar,  I EE£ Conj. Publ. 
 LAYER DESIGN CONSISTING OF OUTER SKINS  A  CENTER SKIN  AND TWO INTERMEDIATE  CORES 4HE SYMMETRICAL # 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.66  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 These performance estimation curves can be used to show extremes in SNR variation,  antenna elevation angles required, and expected clutter-to-noise ratios. The expected  performance of a particular radar design can be explored with these graphs because  summer and winter do give good coverage of the important variables. 
     PP n  n  $ECEMBER   DECLASSIFIED   + 2OGERS  h%NGINEERS UNLOCK MYSTERY OF CAR 
 To counter this, ASV Mk. VI was ﬁtted with an attenuator (known as Vixen) that allowed the transmitted power to be reduced by the radar operator as the target was approached. ASV Mk. 
 LAR TO THAT OF A SMALL AIRCRAFT WITH HIGH YAW RATES BUT SMALLER WINGSPAN (OWEVER  THE LARGER AIRCRAFT TYPICALLY HAS THE BROADER NOISE SPECTRUM BECAUSE OF THE DIFFERENCE IN DISTRIBUTION OF DOMINANT REFLECTORS. °Ón  2!$!2 (!.$"//+  4HE RADAR FREQUENCY AFFECTS THE LOW 
 LEVEL DEVIATION . Ó°Ç{  2!$!2 (!.$"//+  INTRODUCED BY THE !$ CONVERTER IS   ;   =. 
 22 Typical digital beamformer COMPLEX SUMPHASE SHIFT 1 PHASE SHIFT MBEAM 1 BEAM MDDC2 MCSPS RF FR OM 100 ELEMENTSCHAN 1 COMPLEX SUM CHANNEL PR OCESSOR 100CHANNEL PR OCESSOR 1ADC100 MSPS 16I Q20 20 RF RCVR75 MHz IF CHAN 100RF RCVR23 I/Q 23 I/Q100 MHzEQU FIR ch25.indd   18 12/20/07   1:40:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 
 Thus, because the echo signal increases with the square of the load- carrying capacity, string suspension techniques are best suited for measurements of  light objects at low frequencies. The metal target support pylon was first suggested in 1964,54 but a practical imple - mentation of the concept did not appear until 1976. The configuration of the pylon is  shown in Figure 14.22, and it owes its electromagnetic performance to the sharpness of  its leading edge and its tilt toward the radar (to the left in the diagram). 
 In an S-band (3000 MHz) radar, for example, the plumbing losses might be as follows:  100 ft of RG-113/U A1 waveguide transmission line (two-way) 1.0 dB  Loss due to poor connections (estimate) 0.5 dB  Rotary-joint loss 0.4 dB  Duplexer loss 1.5 dB  Total plumbing loss 3.4 dB  Beam-shape loss. The antenna gain that appears in the radar equation was assumed to be a  constant equal to the maximum value. But in reality the train of pulses returned from a target  with ascanning radar is modulated in amplitude by the shape of the antenna beam. 
 DELAY IMPROVEMENT FACTOR TO  D" 4HIS COR 
 Instead, the criterion for reporting a detection might be a threshold crossing on two successive  scans, or threshold crossings on two out of three scans, three out of five, or so forth. In  track-while-scan radars the measure of performance might he the probability of initiating a  target track rather than a criterion based on detection alone.  Surveillance-radar range equation. 
  
 2014 ,7, 1642–1650. [CrossRef ] 20. Guo, J.M.; Zhou, L.; Yao, C.L.; Hu, J.Y. 
 If the target is in  motion with a velocity v, relative to the radar, the received signal will be shifted in frequency  from the transmitted frequency Jo by an amount ± J;i as given by Eq. (3.2). The plus sign  associated with the doppler frequency applies if the distance between target and radar is  decreasing (closing target), that is, when the received signal frequency is greater than the  transmitted signal frequency. 
 As stated earlier, it also contains all the information necessary to  account for natural environmental effects. Thus, if the functional form of F is known,  then the propagation loss at any point can be determined because the calculation of the  free-space field is quite simple. The propagation loss, including antenna parameters,  is equivalent to  L L F = −fs2010log ( ) (26.14) Effective-earth-radius Model. 
 All other error sources  being fixed, compliance with the far-field requirement is generally felt to yield data  with an accuracy of 1 dB or better.49 Figure 14.20 illustrates the far-field requirement  for a variety of frequencies and target sizes. Errors attributable to radar instrumentation should be held to 0.5 dB or less, which  requires careful design and selection of components. The drift in system sensitivity  should not exceed this value for the time it takes to record a single RCS pattern, which  sometimes may approach an hour. 
 The change from pulse topulse is/r R’ R FIG113.20 .-f5canning fluctuation ofthe echo from anextended target. represented bythevector r.Ifitisassumed that thescattering elements areequal insize and randomly distributed, itisnothardl tocalculate the ratio oftherms values ofRand r.The result is (9) 1A.G.Emslie, “Moving Target Indication onME~T, ”RLReport No. 1080, Feb. 
 Õ}iiÊ°Ê ÌÌ 4OMORROWS 2ESEARCH £{°£Ê  /," 1 /"  ! RADAR DETECTS OR TRACKS A TARGET  AND SOMETIMES CAN CLASSIFY IT  ONLY BECAUSE THERE  IS AN ECHO SIGNAL )T IS  THEREFORE  CRITICAL IN THE DESIGN AND OPERATION OF RADARS TO BE ABLE TO QUANTIFY OR OTHERWISE DESCRIBE THE ECHO  ESPECIALLY IN TERMS OF SUCH TARGET CHARACTERISTICS AS SIZE  SHAPE  AND ORIENTATION &OR THAT PURPOSE  THE TARGET IS ASCRIBED AN EFFECTIVE AREA CALLED THE  RADAR CROSS SECTION   OR 2#3 4HE 2#3 IS THE PROJECTED AREA  OF A METAL SPHERE THAT WOULD RETURN THE SAME ECHO SIGNAL AS THE TARGET  HAD THE SPHERE BEEN SUBSTITUTED FOR IT 5NLIKE THE ECHO OF THE SPHERE  HOWEVER  WHICH IS INDEPENDENT OF THE VIEWING ANGLE   THE ECHOES OF ALL BUT THE SIMPLEST TARGETS VARY SIGNIFICANTLY WITH ORIENTATION !S WILL BE SHOWN LATER  THIS VARIATION CAN BE QUITE RAPID  ESPECIALLY FOR TARGETS MANY WAVELENGTHS IN SIZE 4HE ECHO CHARACTERISTICS DEPEND IN STRONG MEASURE ON THE SIZE AND NATURE OF THE  TARGET SURFACES EXPOSED TO THE RADAR BEAM 4HE VARIATION IS SMALL FOR ELECTRICALLY SMALL TARGETS TARGETS LESS THAN A WAVELENGTH OR SO IN SIZE  BECAUSE THE INCIDENT WAVELENGTH IS TOO LONG TO RESOLVE TARGET DETAILS /N THE OTHER HAND  THE FLAT  SINGLY CURVED AND DOUBLY CURVED SURFACES OF ELECTRICALLY LARGE TARGETS ALL GIVE RISE TO DIFFERENT ECHO CHARACTERISTICS 2EENTRANT STRUCTURES SUCH AS JET ENGINE INTAKES AND EXHAUSTS GENERALLY HAVE LARGE ECHOES  AND EVEN THE TRAILING EDGES OF AIRFOILS CAN BE SIGNIFICANT ECHO SOURCES 4HE RADAR CROSS SECTIONS OF SIMPLE BODIES CAN BE COMPUTED EXACTLY BY A SOLUTION OF  THE WAVE EQUATION IN A COORDINATE SYSTEM FOR WHICH A CONSTANT COORDINATE COINCIDES WITH THE SURFACE OF THE BODY 4HE EXACT SOLUTION REQUIRES THAT THE ELECTRIC AND MAGNETIC FIELDS JUST INSIDE AND JUST OUTSIDE THE SURFACE SATISFY CERTAIN CONDITIONS THAT DEPEND ON THE ELECTROMAGNETIC PROPERTIES OF THE MATERIAL OF WHICH THE BODY IS MADE 7HILE THESE SOLUTIONS CONSTITUTE INTERESTING ACADEMIC EXERCISES AND CAN  WITH SOME  STUDY  REVEAL THE NATURE OF THE SCATTERING MECHANISMS THAT COME INTO PLAY  THERE ARE NO KNOWN TACTICAL TARGETS THAT FIT THE SOLUTIONS 4HUS  EXACT SOLUTIONS OF THE WAVE EQUA 
 K. Moore, and J. C. 
 Any use is subject to the Terms of Use as given at the website. Bistatic Radar.  BISTATIC RADAR  23.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 particularly severe when the receiver is located in direct LOS of the transmitter, which  must occur when surveillance of low-altitude air targets is required (Eqs. 23.5–23.8). 
 3.2. The Relationship between Height Di ﬀerence Threshold and System Parameters In this part, we calculate the height di ﬀerence threshold for determining whether the ArcSAR imaging result on the reference plane will severely defocus, and analyze the relationship between the height diﬀerence threshold and the system parameters. We deﬁne the height of the reference plane as href, which the value is 0 m. 
       
 117533. CHAPTER  THREE  CW AND FREQUENCY-MODULATED RADAR  3.1 THE DOPPLER EFFECT  A radar detects the presence of objects and locates their position in space by transmitting  electromagnetic energy and observing the returned echo. A pulse radar transmits a relatively  short burst of electromagnetic energy, after which the receiver is turned on to listen for the  echo. 
 , 
 14.14 becomes kw. The physical optics integral is not dependent on the polar - ization of the incident wave and is unreliable for angles much greater than 30 ° from  broadside incidence. By way of comparison, the physical optics formula for the RCS of a circular metal  disk is  sq lq q=1612 πA J kd kdcos ( sin) sini  (14.15) where A is the physical area of the disk, d is its diameter, and J1(x) is the Bessel func - tion of the first kind of order 1. 
 02& RANGE 
 Mortley, W. S., and S. N. 
 When adding time delay to the sample clock, care must be  taken to avoid adding jitter, which could degrade the A/D converter SNR performance.  Time-delay correction can also be implemented effectively in the digital domain, and  if frequency dependent phase and amplitude imbalance correction is required, this is  most easily and effectively performed in the digital domain using FIR filtering of the  I and Q data or by performing corrections in the frequency domain data as part of the  radar signal processing. Nonlinearity in I and Q Channels. 
 Rangeinformation isextracted fromtheoutputofthesumchannel afteramplitude detection. Sinceaphasecomparison ismadebetween theoutputofthesumchannelandeachofthe dilTerence channels, itisimportant thatthephaseshiftsintroduced byeachofthechannels be almostidentical. According toPage,l JthephasedilTerence between channels mustbemain­ tainedtowithin25°orbetterforreasonably properperformance. 
 TO 
 Even with these limitations, astepped lens is usually  to be preferred because of the significant reduction in weight.  The larger the dielectric constant (or index of refraction) of a solid dielectric lens, the  thinner it witt be. However, the larger the dielectric constant, the greater will be the mismatch  between the lens and free space and the greater the loss in energy due to reflections at the  surface of the lens. 
 Fortunately, satisfactory pulse transformers areavailable tomatch theimpedance of the load tothat ofthe generator. While the elementary theory ofthe pulse transformer isquite manageable, great care indesign must be exercised topreserve good wave shape with fast rates ofrise, aminimum ofextraneous oscillation, and high efficiency. The ideal transformer is shown inFig. 
 4 in Radar Handbook , 2nd Ed., New York: McGraw-Hill, 1990,  Sec. 4.8, “Pulse modulators.” 49. T. 
 Indeed, a phase change ofonecyclethat is,aradial motion ofone-half wavelength between pulses—is equivalent tonochange atall. Thus there arecertain “blind” velocity intervals inwhich the mass motion ofthe target does not lead toadiscernible indication. Since the velocities about which these intervals arecentered aredetermined bythe wavelength and the pulse repetition rate oftheset,itispossible, within limits, toarrange that they fallaslittle aspossible intherange ofvelocities tobeexpected forthe targets ofinterest. 
 But if the output lies between the two thresholds, no decision is possible  :~r)cl ;~r~otl~cr obscrv;~!ion is r~~ntfe.  i 11e Sequerrtial Observer perr~tits a sigrlificarit reductiori in tl~e merage nuniber of sa~liples  (pulses) needed for making a decision. The improvement depends upon whether a signal is  present or not. 
 What is actually happening is that at one  instant a pulse is transmitted and an echo received back,  and this sequence is displayed on a trace; then, the next  . PICTURE ON THE TUBE 163  instant, another pulse is transmitted through a different  aerial (or through the same aerial in a different position),  and the display of the resulting echo along this different  line of shoot is given by a trace and blip display on the  CRT a little distance away from the first display. As  these two displays are being made alternately, probably  more than a hundred times a second, the effect is to show  two echoes simultaneously. 
 Although such events are relatively rare in a fixed area of 10 m2, they should occur  quite frequently within a large surveillance cell and might often have large scatter - ing cross sections associated with them. Similar records may be found in reference  Ward et al.29 Other Environmental Effects. Rain. 
 ALLY LIMITED TO THAT NECESSARY FOR TRACKING TO MINIMIZE LOSS OF TRACK TO FALSE TARGETS AND COUNTERMEASURES -ANY OTHER ELECTRONIC RANGE 
 THETIC APERTURE  THUS FREQUENCY AGILITY HAS  TO BE USED WITH CAR E &REQUENCY CHANG 
 These plans were laid aside for atime when itbecame clear inthis country that several months offighting remained intheEuropean war. When work ontheSeries was resumed intheearly summer of1945, the books planned, asbefore, dealt with basic matters and with techniques. Every effort was made topoint outthegeneral applicability ofthework reported and toavoid special emphasis onitsapplication toradar, since radar itself was thought tohave only alimited importance. 
 TABLE 105.-RELATION OF PCLSE LENGTH TON’UMBER OFh’fESHES Pulse length, Ksec Number ofmeshes 0,14.5 1–3 0.5-2.5 2-5 2,,%5 >8 The greatest obstacle todesign ofacompact high-power network is the bulk ofthe necessary condensers. High-voltage condensers are inordinately large and expensive incomparison with the job they have toperform; allelectronic equipment would profit from a major improvement incondenser design. Though afew new di- electrics have shown promise of increasing the energy stored per unit volume, mica, paper, and oil arestill theprimary dielectrics for high-voltage con dens ers. 
 The difference pattern in the orthogonal plane is obtained by adding  the differences of the orthogonal adjacent pairs. A total of four hybrid junctions generate the  sum channel, the azimuth difference channel, and the elevation difference channel. Three  separate mixers and IF amplifiers are shown, one. 
 SHIFTED IN FREQUENCY  AND THEN SAMPLED WITH A HIGH 
 § ©¨¶ ¸·       WHERE 0N IS THE NOISE POWER 4HIS ESTIMATOR HAS BEEN WIDELY USED IN THE PAST FOR MEAN 
 However, the accuracy isnotasgoodaswithsystems usingthreeorfourbeams. Inprinciple, theCWradarwouldseemtobetheidealmethod ofobtaining doppler­ navigation information. However, inpractice, leakage between transmitter andreceiver can limitthesehsitivity oftheCWdoppler-navigation radar,justasitdoesinanyCWradar.One methodofeliminating theilleffectsofleakageisbypulsingthetransmitter onandturningthe receiver offfortheduration ofthetransmitted pulseinamanner similartothepulse-doppler radardescribed inSec.4.10.Thepulse-doppler modeofoperation hasthefurtheradvantage in thateachbeamcanoperate withasingleantenna forbothtransmitter andreceiver, whereas a CWradarmustusuallyemploytwoseparate antennas inordertoachievetheneededisolation. 
 BEAM CLUTTER  AND SELECTING THE DOPPLER WEIGHTING DYNAMICALLY )F PULSE COMPRESSION MODULATION IS USED ON THE TRANSMIT PULSE TO INCREASE ENERGY ON  TARGET  PULSE COMPRESSION CAN BE PERFORMED DIGITALLY EITHER BEFORE OR AFTER THE DOPPLER . 
 TRANSMIT  SWITCHING !LSO  IF PULSE COMPRES 
 POLARIZED GAINS ARE HIGH  %##- TECHNIQUES SUCH AS 3,# AND 3," MAY NOT BE EFFECTIVE AGAINST CROSS 
   
 Among the single-chip circuit designs that have been reported from UHF through millimeter-wave frequencies are power amplifiers, low-noise amplifiers, wideband amplifiers, phase shifters, atten- uators, T/R switches, and other special function designs. Component Characteristics. Performance characteristics for monolithic cir- cuits vary significantly and are the result of processing variations, layout consid- erations, yield optimization, or circuit complexity. 
 AsimpleCWradarsuchaswasdescribed inSec.3.2isshownin Fig.4.ta.Itconsistsofatransmitter, receiver, indicator, andthenecessary antennas. Inprinci­ ple,theCWradarmaybeconverted intoapulseradarasshowninFig.4.thbyproviding a poweramplifier andamodulator toturntheamplifier onandoffforthepurposeofgenerating pulses.Thechiefdifference between thepulseradarofFig.4.thandtheonedescribed in Chap.1isthatasmallportionoftheCWoscillator powerthatgenerates thetransmitted pulsesisdiverted tothereceiv"ertotaketheplaceofthelocaloscillator. However, thisCW signaldoesmorethanfunction asareplacement forthelocaloscillator. 
 /",Ê / 
 The sampling period is chosen among a finite  number of possible different values based on kinematic considerations on the target  (estimated speed) as well as on whether missed detections have occurred. If there  is no measurement to be associated to the target, the sampling period is set equal to   Ts = 0.1 s and the waveform of highest energy is selected, so as to possibly avoid a  second missed detection due to the possibly low target-RCS. Conversely, the sam - pling period is selected as follows: - Ts = 0.5 s for targets with estimated speed greater than 400 m/s - Ts = 2 s for targets with estimated speed between 100 and 400 m/s - Ts = 3 s for targets with estimated speed less than 100 m/s Even though the target may accelerate or maneuver, for the sake of simplicity, the  sampling period is selected only on the basis of the target estimated speed. 
 Septembcr, 1975. 50.LJlaby.F.T..andP. P.Batlivala: Diurnal Variations ofRadarBackscatter fromaVegetation Canopy. 
 When the  antenna points in tile direction of tile platform velocity (0 = 0), the doppler shift of the clutter  is maximum, but the width of the doppler spectrum llfd is a minimum. On the other hand,  when the antenna is directed perpendicular to the direction of the platform velocity (0 = 90°),  the clutter doppler center-frequency is zero, but the spread is maximum. This widening of the  clutter spectrum can set a limit on the improvement factor. 
 95. A. R. 
 [1(1.130!)I~06.Novemher. 1975. xoKanyuck. 
 ING CAN BE USED ON THE HIGH )& AS DEFINED BY THE SIGNAL BANDWIDTH BEFORE DOWNCONVER 
 For example, in the simplified case of a single  dimension and constant tracking conditions, the measurement covariance matrix is  simply a single, constant measurement variance, ℜk = s�2 m, and the time between detec - tions is a constant Rk = T. In this case, the Kalman filter described in Eqs. 7.29 to 7.33  has gains that are a function of the dimensionless track-filtering parameter gtrack:  γσtrack=qT m3 2  (7.36) Because the radar measurement accuracy, as represented by the covariance matrix  ℜ, and the time between detection opportunities, T, are parameters of the radar design  itself, the selection of Q(tk) is the degree of freedom available to the tracking filter  design. 
 £CENTROID EXTENTSQUARE%$ 0#RI I RR\\ DD TERRAINTOPESTIMATE  4# %RR  r   WHERE 3I IS A SINGLE SUM MONOPULSE MEASUREMENT   $I IS THE CORRESPONDING ELEVATION  DIFFERENCE MONOPULSE MEASUREMENT 5SUALLY THE RANGE 
 RANGE REQUIREMENTS 4HE P ORT 
 TANEOUSLY  LONG 
 Independent control of the  sum arid the difference patterns is required in order to obtain simultaneously the optimum  patterns.  The approximately "ideal" feed-illuminations for a monopulse radar is shown in  Fig. 5.10. 
   NO   PP  
 The  effective length of the synthetic aperture can be limited by the stability of the transmitter or the  receiver.  The heart of the SAR is the processor which must provide the proper amplitude and phase  weights to the stored pulses, and sum them to obtain the image of the scene. Optical processors  and digital processors have both been used. 
 SQUARED  PROFILE BELOW 4HE CLUTTER CROSS 
 The smallest signal  that can be detected by the r adar  is called Minimum Discernible Signal . Smaller powers  than this PMDS aren't usable si nce they are lost in the  noise of the receiver  and its environment . The  minimum power is de tect at the maximum range Rmax  as seen from the equation. 
 31.Stark,L.,R.W.Burns,andW.P.Clark:PhaseShiftersforArrays,chap.12ofRadarHandhook, M.I. Skolnik(ed.),McGraw-Hili BookCo.,NewYork,1970. 32.Clark,W.P.:AHighPowerPhaseShifterforPhased-Array Systems.nEETr£lll\..vol.MTT-I3, pp.785-788, November, 1965. 
 972–982, 1957. 25. Guinard et al., “Variation of the NRCS of the sea with increasing roughness,” J. 
 For short lengths, convolutions small compared with thewave-length can beformed hydraulically, and thereby give flexibility toacontinuous metal tube. Figure 11.1 la!shows anexample. Transitions between waveguide and cooxial lines usually take the form ofaquarter-wave stub antenna onthe coaxiai line projecting into thewaveguide aquarter guide-wavelength from anendplatej asshown in FIG. 
 Resolution= 12 m; aircraft altitude= 40,000 ft (12 km)  This is a mosaic covering approximately 19 by 32 km. (Courtesy Goodyear Aaospace a11.d Litco11 Aero  Service.) (b) A bend in the Huron river (center)just east of Ann Arbor, Michigan. Note football stadium  (with lights) top left center, and large orchard in upper right center. 
 FEED MONOPULSE ARRAYS  INCLUDE THE LENS ARRAY AND REFLECTARRAY #HAPTER   THAT ARE OPTICALLY FED BY A CONVEN 
 CEPTUAL RADAR SYSTEM DESIGN  IS TO START WITH WHAT THE NEW RADAR HAS TO DO  EXAMINE THE VARIOUS APPROACHES AVAILABLE TO ACHIEVE THE DESIRED CAPABILITY  CAREFULLY EVALUATE EACH APPROACH  AND THEN SELECT THE ONE THAT BEST MEETS THE NEEDS WITHIN THE OPERATIONAL AND FISCAL CONSTRAINTS IMPOSED )N BRIEF  IT MIGHT CONSIST OF THE FOLLOWING STEPS.   !. ).42/$5#4)/. !.$ /6%26)%7 /& 2!$!2   £°ÓÎ L $ESCRIPTION OF THE NEED OR PROBLEM TO BE SOLVED   4HIS IS FROM THE VIEWPOINT OF THE CUSTOMER OR THE USER OF THE RADAR L )NTERACTION BETWEEN THE CUSTOMER AND THE SYSTEMS ENGINEER   4HIS IS FOR THE PURPOSE OF EXPLORING THE TRADEOFFS  WHICH THE CUSTOMER MIGHT NOT  BE AWARE OF  THAT MIGHT ALLOW THE CUSTOMER TO BETTER OBTAIN WHAT IS WANTED WITH 
 ASPECT TARGET COVERAGE IS ACHIEVED 3INCE THE SIDELOBE CLUTTER GENERALLY COVERS THE DOPPLER REGION OF INTEREST  THE RATIO OF THE REGION WITH SIDELOBE CLUTTER BELOW NOISE RELATIVE TO THE TOTAL RANGE 
 DUCTORS FOR INSTANCE  USING 'ALLIUM .ITRIDE TECHNOLOGY   PRECISION DIGITALLY CONTROLLED SIGNAL GENERATORS  AND FAST DIGITAL SIGNAL PROCESSORS #OHERENT #-2S ARE DISCUSSED UNDER h3OLID 
 0ULSE )NSTABILITY ,IMIT ON )MPROVEMENT &ACTOR /SCILLATOR PHASE NOISE 3EE DISCUSSION IN TEXT 4RANSMITTER FREQUENCY )    LOG ;O $F  S   = 3TALO OR COHO FREQUENCY )    LOG ;O $F 4 = 4RANSMITTER PHASE SHIFT )    LOG $E  #OHO LOCKING )    LOG $E  0ULSE TIMING )    LOG ;    =TT$T" 0ULSE WIDTH )   LOG ;    =TT$07 " 0ULSE AMPLITUDE )    LOG !$!  !$ JITTER )    LOG ;   =TT*" !$ JITTER WITH PULSE COMPRESSION FOLLOWING !$ )    LOG ;    =TT*" WHERE $F  INTERPULSE FREQUENCY CHANGE         S  TRANSMITTED PULSE LENGTH         4  TRANSMISSION TIME TO AND FROM TARGET         $E  INTERPULSE PHASE CHANGE         $T  TIME JITTER         *  !$ SAMPLING TIME JITTER         "S  TIME 
 The availability of color cathode-ray tubes provides another "dimension" for  the display of target inforrnat ion. Target altitude, cross section, or identity might be color  coded. The outputs from more than one radar or the outputs from each beam of a stacked-  beam radar may be displayed on the same CRT in different color, as can alphanumeric data  or synibols. 
 33. Arenberg, D. L.: Ultrasonic Solid Delay Lines, J. 
 The “negative-going” edge ofthis square wave isthen used totrigger a single-stroke blocking oscillator. The frequency ofthe sinusoidal oscil- lator, and therefore ofthepulses, ismade equal tothat ofthemost closely. SEC.K3.121RANGE ANDHEIGIiT INDICES; SYNCHRONIZATION 521 spaced markers desired.’ Lower-frequency markers are provided by scaling circuits. 
 Table 7.1shows the reported average detection rage, R, for the different radars. Also shown is the implied detection sensitivity (proportional to R 4) relative to ASV Mk. III. 
 AXIS PRODUCES AN ODD 
 DETECTOR OUTPUT TO GENERATE AN ERROR TREND FROM WHICH IT CAN UPDATE THE ASSUMED SET  . °ÓÈ  2!$!2 (!.$"//+  OF ORBITAL PARAMETERS TO CORRECT THE RADAR BEAM MOVEMENT TO UPDATE THE ORIGINAL   SET OF ORBITAL PARAMETERS  AND BY THIS MEANS  THE RADAR ANTENNA AXIS CAN BE HELD ON TARGET WITH MINIMUM ERROR )MPROVED TRACKING CAN ALSO BE PROVIDED ON OTHER TARGETS WHERE THE APPROXIMATE  TRAJECTORY CAN BE ANTICIPATED (OWEVER  PERFORMANCE OF ON 
 The VHF band is crowded with important civilian services such as TV and FM  broadcast, further reducing the availability of spectrum space for radar. External noise  levels that can enter the radar via the antenna are higher at VHF than at microwave  frequencies. Perhaps the chief limitation of operating radars at VHF is the difficulty of  obtaining suitable spectrum space at these crowded frequencies. 
 9.12 and 9.14. 9.4. Nonscan.ning Antennas.-There are certain types ofradar antenna which arenot ordinarily required toscan. 
 '"'"a ca +-­o L0' Q) +-­cen10----------+---- ------+-----------t-r7''----75,<--y<'7''-------j -0 Fi~ureVI(ellIntegration-improvement factor,squarelawdetector, Pd=probability ofdetection. IIf=1/1;.B=falsealarmnumber, 1;-.=averagetimebetweenfalsealarms,B=bandwidth; (b)integra­ tionlossasafunction ofII,thenumberofpulsesintegrated, Pd'andIIf.(AfterMarcum,lo courtesyIRE TrailS.). 32 INTRODUCTION TO RADAR SYSTEMS  and probability of false alarm, or false-alarm number, since tilere is no stantfat-ci~~atiotl ol'  definitions. 
 AIR OBSERVATIONS OF RADIOSONDES  OTHER SENSORS  OR MESO 
   PP n    0 (ARTL  - 2EICH  AND 3 "HAGAVATHULA  h!N ATTEMPT TO CALIBRATE AIR 
 Aerosp. Electron. Syst. 
 Figure 23.9 shows a photograph of the antenna of the airborne doppler radar mounted on the tail of the P-3 aircraft operated by the National Oceanic and Atmospheric Administration (NOAA). The antenna, covered by a cylindrical radome in flight, scans in range- height-indicator (RHI) mode, in vertical planes orthogonal to the aircraft fuselage. The aircraft is flown on orthogonal tracks in order to synthesize dual- doppler observations and therefore to obtain vector winds. 
 CIRCUIT AMPLIFIER TO DRIVE A MODERATE 
 4, pp. 36-48, 1987. 37. 
 In comparison, the CA -, CAGO-  and also,  to some extent the OS - and the CAOS- CFAR, react esse ntially more delayed to these clutter  level changes. This is the reason why the CFAR -loss of the CASH -CFAR is a little higher than  that of the other CFAR methods. CFAR adder circuits favorably influence CFAR- loss. 
 In practice, the radar designer attempts to select the  pulse-repetition period T, so that all targets of interest occur only in the vicinity of the central  peak, all other peaks being far removed from the region occupied by the targets. The periodic-  pulse waveform is a good one from the point of view of accuracy if the radar application is  416INTRODUCTION TORADAR SYSTEMS (al (b)Figure11.10Two-dimensional am­ biguitydiagrlim forasinglepulseof sinewave.(a)Longpulse;(0)short pulse. .} Itisusuallyinconvenient todrawathree-dimensional plotoftheambiguity diagram. 
 The gap inthe TRtube inthereceiving branch likewise breaks down, and ifitisdesigned sothat the discharge takes negligible power tomaintain, puts ashort circuit across theline tothereceiver. The delicate input circuits ofthe receiver arethereby protected. Since theshort circuit isaquarter wave- length from the T-junction, the impedance put inparallel with the antenna line atthe junction isvery high and does not affect the wave traveling toward theantenna. 
 18. Li, H.; Celik, T.; Longbotham, N.; Emery, W.J. Gabor Feature Based Unsupervised Change Detection of Multitemporal SAR Images Based on Two-Level Clustering. 
 (Colrrtesy Raythrorr Con~pntry.)  Figure 7.26 Idealized anlcana pat-  tern assumed in the cortlpcrtatior~ of  the loss in gain incurred with a  cosecant-squared antenna pattern.  (a) Normal antenna pallern; (h)  cosecant-squared pattern.  260INTRODUCTION TORADAR SYSTEMS ·J~!}~l ;,.:..: .,~,...... 
 The maximum power per unit solid angle is obtained simply by inspection,  and the total power radiated is found by integrating the volume contained under the radiation  pattern. Equation (7.2) can be written as  where B is defined as the beam area:  The beam area is the solid angle through which all the radiated power would pass if the power  per unit solid angle were equal to P(O, +),,,,, over the beam area. It defines, in effect, an equivalent  antenna pattern. 
 HF OVER-THE-HORIZON RADAR  20.456x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 these is the spread doppler clutter discussed in Section 20.8, sometimes referred to as  active or multiplicative  noise . The occurrence of this type of clutter is greater at night  and is much more prevalent in the auroral zones and around the magnetic equator . 20.10 THE RECEIVING SYSTEM The receiving system is defined here to embrace only the receiving antenna array and  the receivers that convert the antenna outputs to discrete time series, usually at base - band. 
 *ONES  TOOK THIS INTO ACCOUNT  ASSUMED A GAUSSIAN SHAPE FOR THE ANTENNA BEAM   AND DERIVED THE FOLLOWING EQUATION FOR THE RECEIVED POWER   00' C RRT I I.    £   LQ FT PSL N     WHERE LN IS THE CORRECTION FOR THE GAUSSIAN 
 WEIGHT RATIOS 4HE SKINS ARE GENERALLY FIBERGLASS 
 Inthelast case, the. SEC. 66] PLANE DISPLAYS INVOLVING ELEVATION 173 the display isexpanded inthe vertical dimension, sothat the height interval tobecovered occupies approximately the same distance onthe tube face. 
 The difference in insertion loss between the two paths may be  equalized by padding the shorter arm. The various problems have been comprehen - sively assessed and analyzed by Lincoln Laboratory.45 On transmitting, the tolerances are less severe because the requirements are usually  for power on target rather than for accurate angle determination or low sidelobes. Figure 13.29 b shows another configuration that has the advantage of simplicity. 
 56. Gunn, K. L. 
 Other operator controls adjusted focus and brilliance. Pre-set operator controls for horizontal and vertical shift were also provided on the front panel. Calibration and other alignmentfacilities were pre-set controls within the unit. 
 3CIENCES  !PPLICATIONS  )NC  2!$# 
 Doppler filter banks are satisfactory for acquisition and for track-while-scan radars. They are not commonly used in tracking radars or illuminators to improve SNR since the use of a doppler tracker (speedgate) is far less complex. The usual speedgate circuit is identical with the AFC circuit in an FM radio. 
 Wanted signals shall on the  one hand  reach the indication as of minimal amplitude ; on the other hand the false alarm rate may not  increase.      100%Ddetected targetsPall possible blibs   The system must detect, with greater than or equal to 80% probability at a defined range, a one  square meter rada r cross section.  Radar Range Equation Parameter    Metric units  Decibels   Radiated Power Ptx 1· 10 6 W 60 dBW   Antenna Gain G 1900  32.8 dB   Transmitters Wavelength λ (at 2,700 MHz)  0.11m   Radar Cross Section σ (e.g. 
 J. T. Rickard and G. 
 86. Case, Jr. et al., “Radar for Automatic Terrain Avoidance,” U.S. 
 In general, for most applications of radar at microwave frequencies, the attenuat~on in  propagating through either the normal atmosphere or through precipitation is usually not  sufficient to affect radar performance. However, the reflection of the radar signal from rain  (clutter) is often a limiting factor in the performance of radar in adverse weather.  The decreasing density of the atmosphere with increasing altitude results in a bending, or  refraction, of the radar waves in a manner analogous to the bending of light waves by an  optical prism. 
 8. Shrader, W.W.: MTI Radar, chap. 17 of" Radar Handbook," M. 
 FREQUENCY COMPONENTS ARE LIGHTLY SHADED 4O SEE THE EFFECT OF SAMPLING THIS SIGNAL AT .YQUIST RATE  "  THE LONG  SHEET IS CUT INTO SMALLER SHEETS  WITH THE FIRST CUT AT ZERO FREQUENCY AND SUBSEQUENT CUTS AT SAMPLE 
 AES-9, pp 84 -92. January. 1973. 
 H ichigan Radiation Lah. Swdies in Radar Cross Sections X, Rept. 2255-20- T on Con! racl :\ F  30(602)-1070, July, 1956. 
 Insects are examples of the latter. ANGLE 9 (degrees) FIG. 11.12 RCS patterns of a trihedral corner reflector. 
 H. Von Aulock, “Properties of phased array,” IRE Trans . Vol. 
 It has also been suggested that the cross-  polarized component of the backscattered echo from simple axially symmetric objects (such as  disks, cones, and cone-spheres) can provide an estimate of a transverse dimension of the body  and give an indication of the severity of the edges, or "edginess."47  436INTRODUCTION TORADAR SYSTEMS Synthetic aperture radar.Thesyntheti<;: aperture radar,whichisdiscussed inSec.14.1,isa radarinamovingvehiclethatprovides ahighresolution imageinbothrangeandina direction paralleltothevehiclemotion.Thelatterdimension issometimes calledcrossrange whentheradaruses aside-looking antenna ~irected. perpendicular tothedirection ofmotion. Therangeresolution isobtained witheitheraconventional short-pulse orpulse-compression waveform, andresolution incrossrangeisobtained bysynthesizing theeffectofalarge antenna aperture.Itisusedchieflyformapping ofthegroundandimaging ofstationary objectsontheground. 
 asmightbeobtained fromacompass, mustalsobeknownforpropernaviga­ tion.Thevertical reference maybeusedeithertostabilize theantenna beamsystemsoasto alignitwiththehorizontal. oralternatively, theantennas mightbefixedrelativetotheaircraft andthegroundvelocity components calculated withacomputer. 1\practical formofdoppler-navigation radarmighthavefourbeamsoriented asin Fig.3.19b.Adoppler-navigation radarwithforward andrearward beamsiscalledaJanlls system, aftertheRoman godwholookedbothforward andbackward atthesametime. 
 GROUND ECHO  16.376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 FIGURE   16. 29 Boundaries of measured radar return near vertical incidence,  based on Sandia Corporation data ( from F . J. 
 Fast recovery is required to minimize de- sensitization in the range gates following the transmitted pulse. RF Attenuator. The RF attenuator is used both for suppressing transmitter leakage from the R/P into the receiver (so that the receiver is not driven into sat- uration, which could lengthen recovery time after the transmitter is turned off) and for controlling the input signal levels into the receiver. 
 "1-Ê "  ® 4HE SUSCEPTIBILITY OF CONICAL SCANNING AND SEQUENTIAL LOBING TRACKING TECHNIQUES TO  ECHO AMPLITUDE FLUCTUATIONS AND AMPLITUDE JAMMING AS DESCRIBED IN 3ECTION    WAS THE MAJOR REASON FOR THE DEVELOPMENT OF TRACKING RADAR THAT PROVIDES SIMULTANE 
 As mentioned earlier, most HF skywave radars employ a broad  transmit beam to illuminate a zone of interest, and then process the echoes via a num - ber of much higher resolution simultaneous “finger” beams. It is well known that the  classical resolution of an array improves linearly with aperture up to some limiting  value determined by the environment. Horizontal apertures of 2–3 km and even greater FIGURE 20.20  Diurnal variation of HF noise, measured in dBW/Hz, at latitude 23.6 S, longitude   133.1 E, 5 November 1995 Frequency (MHz)40 35 30 25 20 15 10 ++++ +++++ +++ −180−185 −170 −165 −160 −160−155−165−175 −175 −180 −185 0 5 10 15 20 Time of da y (UT) ch20.indd   45 12/20/07   1:16:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 J.: A noise Silencing 1.F. Circuit for Superheterodyrn: Receivers, QST, vol. 2ll. 
 Contents     xxxi   Severe Storm Warning  .......................................  23.19  23.6 Research Applications  ............................................  23.23  Multiple-Parameter, Radar  ................................. 
 The  wider a pulse, the greater the energy contained in the pulse  for a given amplitude. The greater the transmitted pulse  power, the greater the reception range capability of the radar.   Greater pulse width also increases the average transmitted  power. 
 ,Ê 
 ARRAY ANTENNAS THAT SUPPORT A VARIETY OF MODES INCLUDING  
 18-44~50 Other bistatic radar concepts were identified and tested at this time, such as clutter tuning from an airborne transmitter and receiver. 51~53 One potential im- plementation of this concept allows the receiver to generate a synthetic aperture radar (SAR) map of modest resolution directly on its velocity vector—an impos- sible task for the monostatic SAR. Clutter tuning combined with the sanctuary concept protects the transmitter while allowing the receiver platform to fly to- ward the target with no radar emissions. 
 TION AND RADAR REMAIN THE PRIMARY METHODS FOR DETERMINING THE RISK OF COLLISION WITH OTHER VESSELS AND ALSO WITH FLOATING DEBRIS AND ICE !UTOMATIC )DENTIFICATION 3YSTEMS !)3SEE 3ECTION   OFFER POTENTIAL TO ASSIST WITH COLLISION AVOIDANCE OF COOPERA 
 QUENCY SPACING OF  FCLK  .E &OR EXAMPLE  WITH A  '(Z CLOCK AND  
 Geosc. Electron. ,  vol. 
 The solution was the same: embed the engines’ intakes in the top side of the airframe.  Possibly because the B-2 had a different mission than the F-117 did, Northrop did  not install egg-crate grillwork over the engine intakes. Indeed, Northrop designers  devised hinged cowlings that open up at landing and takeoff speeds to increase air - flow into the engines. 
 This shaping is accomplished by increasing the rate of change of frequency  modulation near the ends of the pulse and decreasing it near the center. This serves  to taper the waveform spectrum so that the matched filter response has reduced time  sidelobes.16 Thus, the loss in signal-to-noise ratio associated with frequency domain  weighting (as for the LFM waveform) is eliminated. If a symmetrical FM modulation is used (Figure 8.9 a) with time-domain amplitude  weighting to reduce the frequency sidelobes, the nonlinear-FM waveform will have a  thumbtack-like ambiguity function (Figure 8.10). 
 Iftheoutputofthereceiver isproportional tothelogarithm oftheinput envelope, itiscalledalogarithmic receiver.Itfindsapplication wherelargevariations ofinput signalsareexpected.Itmightbeusedtoprevent receiver saturation ortoreducetheeffects ofunwanted cluttertargetsincertaintypesofnon-MTI radarreceivers (Sec.13.8). Thedetection characteristics (probability ofdetection asafunction oftheprobability of falsealarm,signal-to-noise ratio,andthenumber ofhitsintegrated) forthelogarithmic receiver havebeencomputed byGreen,44 following themethods ofMarcum.43For10pulses integrated, thelosswiththelogarithmic receiver isabout0.5dB,whilefor100pulsesin­ tegrated, thelossisabout1.0dB.Asthenumber ofpulsesincreases, thelossduetoalogarith­ micdetector approaches amaximum value'of1.1dB.45 Zero-crossings detector. Theinformation contained inthezerocrossings ofthereceived signal can,inprinciple, beusedfordetecting thepresence ofsignals innoise.Thegreaterthe signal-to-noise ratiothelesswillbetheaveragenumberofzerocrossings. 
 This is an unknown value of the radar, but it is one that is directly calculated. To detect a  target, this po wer must be greater than the minimum detectable signal of the receiver.   . 
 When thetwo areequal, anazimuth mark isput ontheradar indicator electronically. The range information provided bythe resolver ismeasured hori- zontally along the ground; itmust becorrected forthe altitude ofthe aircraft if,asisusual, slant range isdisplayed by.the radar indicator. This isdone bymeans oftheelectrical triangle-solver labeled ‘‘Slant range circuit, “into which thevalue ofaircraft altitude issetbythe operator. 
 PONENTS N r % AND N r ( ARE APPROXIMATED BY THEIR GEOMETRIC OPTICS VALUES 4HAT IS   A TANGENT PLANE IS PASSED THROUGH THE SURFACE COORDINATE AT THE PATCH  D3  AND THE TOTAL  SURFACE FIELDS ARE TAKEN TO BE PRECISELY THOSE THAT WOULD HAVE EXISTED HAD THE SURFACE AT D3 BEEN INFINITE AND PERFECTLY FLAT )N ESSENCE  WE DO NOT KNOW THESE FIELDS  BUT WE  TAKE OUR BEST GUESS AS TO WHAT THEY ARE AND INSERT THAT ESTIMATE INTO EITHER OF THE TWO INTEGRALS 4HAT DONE  THE ESTIMATE OF THE UNKNOWN FIELDS IN THE INTEGRALS OF %QS  AND  MAY BE EXPRESSED ENTIRELY IN TERMS OF THE KNOWN INCIDENT FIELD VALUES 4HE PROBLEM THEN BECOMES ONE OF EVALUATING THE CHOSEN INTEGRAL AND SUBSTITUTING THE RESULT INTO %Q  TO OBTAIN THE 2#3&)'52%   4HE GEOMETRIC OPTICS 2#3 OF A DOUBLY CURVED SURFACE DEPENDS  ON THE PRINCIPAL RADII OF CURVATURE AT THE SPECULAR POINT 4HE SPECULAR POINT IS WHERE  THE SURFACE NORMAL POINTS TOWARD THE RADAR . £{°ÓÓ  2!$!2 (!.$"//+  )F THE SURFACE IS A GOOD CONDUCTOR  THE TOTAL TANGENTIAL ELECTRIC FIELD IS VIRTUALLY ZERO  AND THE TOTAL TANGENTIAL MAGNETIC FIELD IS TWICE THE AMPLITUDE OF THE INCIDENT TANGENTIAL  MAGNETIC FIELD   N%r       NN NIr r(( ILLUMINATEDSURFACES SHADEDSURFACEESª«¬   .OTE THAT THE TANGENTIAL COMPONENTS OF BOTH THE ELECTRIC AND THE MAGNETIC FIELDS  ARE SET TO ZERO OVER THOSE PARTS OF THE SURFACE SHADED FROM THE INCIDENT FIELD BY OTHER  BODY SURFACES /THER APPROXIMATIONS MAY BE DEVISED FOR NONCONDUCTING SURFACES )F THE INCIDENT WAVELENGTH IS LONG ENOUGH  FOR EXAMPLE  THE SURFACE OF A SOAP BUBBLE OR THE LEAF OF A TREE MAY BE  MODELED AS A THIN MEMBRANE  OVER WHICH NEITHER THE ELECTRIC  NOR MAGNETIC FIELDS ARE ZERO 4HE PHYSICAL 
 BANDWIDTH PRODUCT OF THE ,&- WAVEFORM IS  MUCH GREATER THAN UNITY SO THAT THE TIME SIDELOBE PERFORMANCE IS NOT LIMITED BY THE &RESNEL AMPLITUDE RIPPLE IN THE SPECTRUM OF THE ,&- WAVEFORM #OOK AND 0AOLILLO   AND #OOK AND "ERNFELD HAVE ANALYZED THE EFFECT OF THE &RESNEL AMPLITUDE RIPPLE AND  PULSE RISE 
 # *APANS 0!,3!2 IS THE FIRST OPERATIONAL SPACE 
 The Fourier series may be used to synthesize the pattern of a discrete array, just as the  Fourier integral may be used to synthesize the pattern of a continuous aperture.74 Similar  conclusions apply. The Fourier-series method is restricted in practice to arrays with element  spacing in the vicinity of a hair wavelength. Closer spacing results in supergrain arrays which  are not practical.75·76 Spacings larger than a wavelength produce undesired grating lobes. 
 OF 
 IEEECat.no.75 CliO938-1AES. 117.Guenther, BD.,J. J.Bennett. 
 TION BECAUSE CLUTTER CANCELLATION IS INADEQUATE . x°{ä  2!$!2 (!.$"//+  !N EXAMPLE THRESHOLDING SCHEME BASED ON THESE CONCEPTS IS SHOWN IN &IGURE   4HE RANGE 
 320, pp. 431–433, 1986. 146. 
 Therefore, radar range prediction is not an exact science. (In fact, the lesson of quantum mechanics seems to be that there is no such thing as an exact science in the strict sense.) Nevertheless, calculations to predict radar range are useful. However inexact they may be on an absolute basis, they permit meaningful comparisons of the ex- pected relative performance of competing system designs, and they indicate the relative range performance change to be expected if the radar parameters or en- vironmental conditions are changed. 
 GRAZING ANGLES TEND TO BE EXTREMELY hPATCHYv BECAUSE ANY  PROJECTIONS ABOVE THE SURFACE TREES  HILLS  BUILDINGS  FENCES  POWER LINES  MACHINERY  AND VEHICLES  PRESENT SURFACES MORE NEARLY NORMAL TO THE BEAM 4HUS NEARBY PIXELS MAY HAVE CLUTTER STRENGTH DIFFERING BY TENS OF D" -OREOVER  SMALL SLOPES FACING THE RADAR INCREASE THE GRAZING ANGLE  RESULTING IN STRONGER ECHOES  WHEREAS SLOPES AWAY FROM THE RADAR DECREASE THE SIGNAL OR MAY OBLITERATE IT BY SHADOWING "ECAUSE OF THIS EFFECT  THE PROBABILITY DISTRIBUTIONS OF NEAR 
 553 556, May. 1971.  28. 
 MATCHED APERTURES "ETTER COMPONENTS SUCH AS RADIATING ELEMENTS  PHASE SHIFTERS  AND POWER DIVIDERS ARE NOW AVAILABLE -ORE ECONOMICAL SOLID 
 1.6 England, France, and Germany, about tenyears after theoriginal work ofBreit and Tuve. The research agencies oftheAmerican Army and Navy have along and complicated history ofearly experiment, total failure, and qualified suc- cess inthe field ofradio detection. The interested reader will find this dealt with atlength inDr. 
 Special mention should be made, however, of the many contributions in two volumes (13 and 24) of the MIT Radiation Labo- ratory Series, edited by Kerr15 and by Lawson and Uhlenbeck.16 Much use is made in this chapter of results originally published in those volumes. 2.2 RANGEEQUATIONS Radar Transmission Equation. The following equation, in the form given in Kerr,15 is called the transmission equation for monostatic radar (one in which the transmitter and receiver are colocated): P1. 
 IT-14, no. 5, pp. 734–743, September 1968. 
 Lett. 2011 ,8, 661–665. [ CrossRef ] 16. 
 (11.26) and (11.27). And because surface terms have been sup- pressed explicitly by the subtraction of the PO coefficients, the effects of surface currents (as distinguished from filamentary edge currents) must be accounted for independently. Those surface terms may be obtained, for example, by using geo- metrical optics or, paradoxically, the theory of physical optics after the edge terms themselves have been computed. 
 FIGURE 25.4 3 Phase shifts inferred by various twiddle factorsW 8 = π/4 1W 8  = 0W 4  = 00 W 8  = 2W 4  = π/21 W 8 = 3π/43 W 8  = 4W 4  = π2W 8 = 5π/45W 8= 6W 4  = 3π/23W 8 = 7π/47 ch25.indd   34 12/20/07   1:40:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 
 AMPLITUDE CLUTTER BACKGROUND .OMENCLATURE  2ADARS THAT RELY ON THE DOPPLER EFFECT TO ENHANCE TARGET DETEC 
 Okean, H. C., and A. J. 
 Against a conically scanning tracking radar, an inverse-gain repeater jammer has the  effect of causing positive feedback, which pushes the tracking-radar antenna away  from the target rather than toward the target. Inverse-gain jamming and RGPO are  combined in many cases to counter conical-scan tracking radars.3 The vulnerability of  conical scan to such countermeasures motivates the use of monopulse trackers that are  almost always used in military tracking radars. A different form of DECM used against the main beam of surveillance radar  attempts to cover the target’s skin return with a wide pulse in order to confuse the  radar’s signal-processing circuitry into suppressing the actual target return. 
 Radar resolution is  usually divided into two categories; range resolution and angular (bearing) resolution.   Angular Resolution   Angular resolution is the min imum angular  separation at which two equal targets at the same  range can be separated. The angular resolution  characteristics of a radar are determined by the  antenna beam width represented by the -3 dB  angle Θ which is defined by the half -power ( -3 dB)  points. 
 SPEED FRONT END OF RADAR SIGNAL PROCESSORS  PERFORMING DEMAND 
 12.10. The synchronizer unit includes the primary timing circuits, and the sweep, range-mark, and intensifier circuits. Onitsfront panel arethe operating controls forthe system. 
 175-178, September, 1957.  46. Scholtz, R. 
 .. r 
 In some cases, they can be used to measure the height of elevated objects above  a flat terrain. FIGURE 17.12  SAR scene containing vibrating target: Crossrange is hori - zontal; range is vertical. The paired echoes in crossrange are characteristic of a  vibrating target (truck with engine running) in a SAR image. 
 Anerror signal ineither coordinate will cause theantenna tomove inthedirection neces- sary toreduce. theerror. This so-called “automatic angle tracking” was. 
 The bearnwidth inradians isA/Wtoa good approximation; substituting this expression forewehave Rm!..=~2JJ”%x>+, (8) From Eq. (8)weseethat ifthebeamwidth issharpened bvdecreasing the\vavelengt hand holding the antenna width constant, R~.,decrrases slowly, The variation ofR~.,with antenna width iscomparati~rely rapid, Ifthebearnw-iclth issharpened tothepoint where thenumber of pulses perscan onthetarget (IV,.) issmaller than about 10,Eq. (8]no longer holds. 
 Vi\. rr.215220,liTECal.no.75CliO938-1i\ES. RO.Meyer, J.W.:Millimeter WaveResearch: Past.Present, andFuture.IHITLillcolllLah.Tech. 
 Ifitwerepractical toamplitude-weight thetransmitted waveform toreducethetime sidelohes, thereceiver canbedesigned withtheappropriate matched filtersothatnotheoreti­ callossinsignal-to-noise willresult.Thisimpliesthatthetransmitted signalener.gyisthesame withorwithout weighting, asfollowsfromthediscussion inSec.10.2oftheoutputsignal-to­ noiseratioofamatched filter.However, whenthetransmitter ispeak-power limited, itis preferable touseaconstant-amplitude transmitted signalandperform theweighting inthe receiver, inspiteofthemismatched filterwithitsreduction insignal-to-noise ratio.25Inone example,24 transmitting alinear-FM waveform withagaussian envelope andamatched-filter receiver togive-40dBsidelobes resulted in2.2dBgreaterpenalty indetection capability thanwhenauniform amplitude istransmitted withHamming weighting onreceiveina mismatched filter. Itispossible toachieve lowtime-sidelobes withuniform-amplitude transmitted wave­ formsandnotheoretical lossinsignal-to-noise ratiobymeansofnonlinear FM,asdis­ cussedlaterinthissection. Doppler-tolerant waveform. 
 REFERENCES 1. Serafin, R. J.: New Nowcasting Opportunities Using Modern Meteorological Radar, Proc. 
 8-10, 1977, Arlington, Va,  pp. 46-51. IEEE Publication 77CH1250-0 AES. 
 #OUNTER -EASURE %#- %LECTRONIC #OUNTER -EASURE %,).4 %,ECTRONIC ).4ELLIGENCE %-#/. %-ISSION #/.TROL %0 %LECTRONIC 0ROTECTION %20 %FFECTIVE 2ADIATED 0OWER %3 %LECTRONIC 3UPPORT %3- %LECTRONIC WARFARE 3UPPORT -EASURE %7 %LECTRONIC 7ARFARE &&4 &AST &OURIER 4RANSFORM &0'! &IELD 0ROGRAMMABLE 'ATE !RRAYS  &4# &AST 4IME #ONSTANT '! 'ENETIC !LGORITHM '3,# 'ENERALIZED 3IDE ,OBE #ANCELER (/* (OME /N *AM (& (IGH &REQUENCY )& )NTERMEDIATE &REQUENCY )-- )NTERACTING -ULTIPLE -ODEL )3!2 )NVERSE 3YNTHETIC !PERTURE 2ADAR *#2 *AMMER #ANCELLATION 2ATIO *$O! *AMMER $IRECTION OF !RRIVAL *.2 *AMMER 
 Gill, T. P.: "The Doppler Effect," Academic Press, New York, 1965.  24. 
 This is well known to be untrue. To remedy this difficulty, several factors must be considered. It is convenient to do this in terms of a particular transmitted waveform. 
 LAYER OF THE ION 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°Î WITHIN THE TRACKING GATES AND THE STATISTICAL DISTANCE BETWEEN THE DETECTION AND TRACK )F  THE DETECTION IS OUTSIDE THE TRACK GATE  THE STATISTICAL DISTANCE IS SET TO INFINITY .EAREST 
 BIT FLUX 
 R. L. Mitchell, Radar Signal Simulation,  Chapter 11, Norwood, MA: Artech House, Inc., 1976. 
 an algorithm is available that requires approximately (N/2) log2 N multiplications  instead of (N I )2. wlticlt results in a considerable saving in processing time. This is the.f<1st  Fo11ria trw1sfi1r111 (FFT), which has been widely described in the literature.11·27 29  Since each filter occupies approximately 1/Nth the bandwidth of a delay-line canceler, its  signal-to-noise ratio will be greater than that of a delay-line canceler. 
 I. Skolnik, Introduction to Radar Systems , 3rd Ed., New York: McGraw-Hill, 2001. 142. 
 REAL 
 A more exact expression, which has frequency dependence, must be used if the ra- tio flT exceeds about 108, where/is the frequency in hertz and T is the kelvin temperature of the resistor. Thus Eq. (2.29) is sufficiently accurate at a frequency of 30 GHz if the temperature is at least 300 K. 
 POLAR VERTICAL REFLECTIVITY  : CX V  NORMALIZED BY THE  CO 
 Design. and Performance of Over-the-Horizon Radars. l11tcmati,111al  Co11frrc11cc R:1/J:1R-77. 
 BACK RADAR  4RANSMITTERS 
 3. I'he frequency of tlie direct arid tlie scattered signals. These will be differknt if the target is in  motion (doppler effect). 
 This in turn requires the computation of Bessel functions of complex argument, not an insignificant undertaking. Quite simple formulas for the scattering width may be obtained in the Rayleigh region, how- ever, for which the cylinder diameter is much smaller than the incident wave- . length. 
 Estimation and interpretation of this modulation yields  information on the time-varying sea surface geometry with major implications for ship  detection as discussed below. It transpires that a relatively simple model accounts for the observed properties of  sea clutter with remarkable fidelity, provided the sea is not too rough. This model is  based on two assumptions: 1. 
 of the 1989 Southeastcon , session 10B6, pp. 85–89.  41. 
 Such asystem isdescribed inthe following section.. SEC. 7.6] THEU.S.TACTICAL AIRCOMMANDS 229 706. 
 768-773, November, 1966. J  62. ~ecker, J. 
 The minus sign applies if the distance is increasing (receding  target). The received echo signal at a frequency Jo ±.fd enters the radar via the antenna and is  heterodyned in the detector (mixer) with a portion of the transmitter signal Io to product: a  doppler beat note of frequency fd. The sign of.fj is lost in this process. 
 IEEE Trans .. vol.  t\FS-11. 
 S. (ed.): "Microwave Antenna Theory and Design," MIT Radiation Laboratory Series.  vol. 
 M. Phillips and K. Hasselmann (eds.), New York:  Plenum Press, 1986, pp. 
 s = ). tl1c i11dex of refraction is equal to 0.866. The closer the spacing, the less will be  the index of refractio11 and the thi1111er will be the Jens. 
 4(% 
 Zrnic, and D. S. Sirmans, “Doppler weather radar,” in Proceedings of the  IEEE,  vol. 
 TO 
 M. Radar:" Digital Signal Processing," IEEE Press, New York, 1972.  12. 
 (23a) isalso the arithmetical average forthe case ofanoncoherent signal from asignal generator. Measurements can therefore bemade without appreciable error byusing thesignal from asignal generator instead ofthat due toan actual target. Amoving-target orsignal-generator pipcan beexpected tobevisible onthe PPI if?isatleast three times the rms clutter fluctuation r~. 
 SITIVITY IF PHASE RUN 
 TION WHEN WORKING ON DIFFERENT SHIPS 4HE RADAR DISPLAY SHOULD ALSO COMPLY WITH )-/S PERFORMANCE STANDARDS FOR NAVIGATIONAL DISPLAYS  #ERTAIN RANGE SCALES MAXIMUM DISPLAYED RANGES  ARE MANDATORY  COVERING  TO   NM )N PRACTICE  RANGE SCALES ABOVE  NM ARE NORMALLY PROVIDED  TYPICALLY UP TO  NM 2ANGE RINGS MAY BE OPTIONALLY SWITCHED IN BY THE OPERATOR TO HELP ESTIMATE DIS 
 ¤ ¦¥³ µ´ 
   
 J. C.. Jr.: A 1)iscrrssion of Iligital Processing in Synthetic Apcrturc Radar. 
 ELEVATION PROFILE IS MEASURED IN MULTIPLE SEGMENTS WITH SEPARATE  02&S AND PULSEWIDTHS 4HE LOWEST 02& IS USED TO MEASURE THE LONGEST 
 A second correlator, the B correlator, resolves the range ambiguities out to the same range, but before a target can enter the B correlator, its amplitude is thresholded by a range-varying threshold (the STC threshold). A range-cell by range-cell compar- ison is made of the correlations in the A and B correlators, and if a range gate correlates in A and not in B, that gate is blanked out of the third correlator, the C correlator. The C correlator resolves the range ambiguities within the maximum range of interest. 
 18. Kalmus, H. P.: Direction Sensitive Doppler Device, Proc. 
 The tradeoff that has to be sought between the accuracy of weights estimation and  the reaction time of the adaptive system 12. The limited number of time samples available to estimate the jammer covariance  matrix; usually 3 N sample should be available if N is the number of adaptive  channels101 13. The antenna rotation rate that might produce a fast time varying power and  jammer DoA101 Joint SLB and SLC. 
 DOM AND IS ASSUMED TO BE WHITE 4HE RMS QUANTIZATION NOISE IS  1   AND SIGNAL 
 £Ó°În  2!$!2 (!.$"//+  &)'52%   'ROUND 
 A practical for111 of dol~pler-riavigatiori radar nliglit liavc four beams oriented as in  Fig. 3.19h. A doppler-navigation radar with forward and rearward beams is called a Jarllrs  system, after the Roman god who looked both forward and backward at the same time. 
 3,   pp. 1816–1819, 1989. 170. 
 lector. The output of the phase detector is a function of the relative phase of the signal and the coho, and it is also a function of the amplitude of the signal. At the output of the phase detector, the signal phase and amplitude information has been converted into bipolar video. 
 LATION AND POOR RANGE SIDELOBE PERFORMANCE  D" #OMPRESSION 0OINT  4HE INPUT  D" COMPRESSION POINT OF A RECEIVER  IS A MEASURE OF THE MAXIMUM LINEAR SIGNAL CAPABILITY AND IS DEFINED AS THE INPUT POWER LEVEL AT WHICH THE RECEIVER GAIN IS  D" LESS THAN THE SMALL SIGNAL LINEAR GAIN 2ECEIVER GAIN COMPRESSION CAN RESULT FROM COMPRESSION IN AMPLIFIERS  MIXERS  AND OTHER COMPONENTS THROUGHOUT THE RECEIVER CHAIN 4YPICALLY  THE RECEIVER IS DESIGNED TO PROVIDE CONTROLLED GAIN COMPRESSION THROUGH A LIMITING STAGE AT THE FINAL )& AS DESCRIBED IN 3ECTION  !NALOG 
 However, thesignal can bemissed iftheclutter issostrong astosaturate thereceiver com- pletely. This can beavoided byreducing therccciver gain tothepoint where theclutter isbelow saturation. Such aprocedure would besatis- factory ifthecl~ltter ]vere everywhere uniform, which itnever is. 
 Through adoptionof the proposed imaging approach, clear target images are available, provided with the shapes and location information of the knife, full bottle of water, half bottle of water and bottles of Coco-cola in the chamber. Figure 20. InISAR imaging results of anechoic chamber target with 20% data. 
 or mountains produce echo signals that are constant in both phase and amplitude as a  function of time, there are many types of clutter that cannot be considered as absc,lutely  stationary. Echoes from trees, vegetation, sea, rain, and chaff fluctuate with time, and these  fluctuations can limit the performance of MTI radar.  Because of its varied nature, it is difficult to describe precisely the clutter echo signal. 
 1.5 RADAR DEVELOPMENT PRIOR TO WORLD WAR II  Although the development of radar as a full-fledged technology did not occur until World War  II, the basic principle of radar detection is almost as old as the subject of electromagnetism  itse1f. Heinrich Hertz, in 1886, experimentally tested the theories of Maxwell and demonstrated  the similarity between radio and light waves. Hertz showed that radio waves could be reflected  by metallic and dielectric bodies. 
 Artificial-dielectric lensesmaybe designed inthesamemanner asotherdielectric lenses. Metal-plate lens.49-52Anartificial dielectric maybeconstructed withparallel-plate wave­ guidesassl\OwninFig.7.19.Thephasevelocity inparallel-plate waveguide isgreaterthanthat infreespace;hencetheindexofrefraction islessthanunity.Thisisopposite totheusual opticalrefracting medium. Aconverging metal-plate lensistherefore thinneratthecenterthan attheedges,asopposed toaconverging dielectric lenswhichisthinnerattheedges.The metal-plate lensshowninFig.7.19isanE-plane lenssincetheelectric-field vectorisparallelto theplates.Snell'slawisobeyedinanE-plane lens,andthedirection oftheraysthrough the lensisgoverned bytheusualopticallawsinvolving theidexofrefraction. 
 Sullivan is grateful to SciTech for permission to quote  considerable material from the chapters on SAR. He is also grateful to Mr. Michael Tuley (Institute for Defense  Analyses) for reviewing the manuscript prior to publication and suggesting many improvements. 
 Radar’s ability to separate returns from different  ranges can be used advantageously along with directive antenna beams to simplify the  scattering measurements. Most ranging scatterometers use either pulse modulation or  FM, although more exotic modulations could also be used. The discussion here treats  pulse systems, but since all other range-measuring systems can be reduced to equiva - lent pulse systems, most results are general. 
 July. 1970.  71. 
 A number of plan-position-indicator (PPI) photographs, taken years ago, are  included in this chapter to provide a better understanding of the environment that is  difficult to appreciate with many modern radars. These photographs show MTI opera - tion, birds, insects, and ducting better than can be described in words. Attention is especially directed to the final section in this chapter, “Considerations  Applicable to MTI Radar Systems,” which provides insight into both hardware and  environmental lessons learned during many decades of MTI system development. 
 44 INTRODUCTION TO RADAR SYSTEMS  Table 2.2 Example radar cross sections at microwave frequencies  Conventional, unmanned winged missile  Small, single engine aircraft  Small fighter, or 4-passenger jet  Large fighter  Medium bomber or medium jet airliner  Large bomber or large jet airliner  Jumbo jet  Small open boat  Small pleasure boat  Cabin cruiser  Ship at zero grazing angle  Ship at higher grazing angles  Pickup truck  Automobile  Bicycle  Man  Bird  Insect Square meters  0.5  I  2  6  20  40  100  0.02  2  10  See Eq. {2.38)  Displacement tonnage  expressed in m2  200  100  2  1  o.oi  10-s  where er= radar cross section in square meters,!= radar frequency in megahertz, and Dis the  ship's (full load) displacement in kilotons.31 This expression was derived from measurements  made at X, S, and L bands and for naval ships ranging from 2000 to 17,000 tons. Although it  is probably valid outside this size and frequency range, it does not apply to elevation  angles other than grazing inc;idence. 
 On reception, a separate receive  beam must be generated for each direction of transmission. In a surveillance application this  could require the complication of some sort of beam-forming. In a tracking phased-array  radar, however, a single time-shared receive beam can be used simultaneously to track many  targets at different angular directions. 
 Thelinearanalysis ofMTIsignalprocessors istherefore notadequate whenIimit­ ing,isemployed andcanleadtodisappointing differences between theoryandmeasurement of actualsystems. Limiters neednotbeusediftheMTIislinearovertheentirerangeofcluttersignalsandif theprocessor hassufficient improvement factortoreducethelargestcluttertotrenoiselevel. Toaccomplish thisthesignalprocessor mustprovide atleast60dBimprovement factor, whichisadifficulttask.56Notonlymustthesignalprocessor bedesigned toreducetheclutter bythisamount, butthereceivermustbelinearoverthisrange,theremustbeatleasteleven bitsintheAIDconverter ofthedigitalprocessor, theequipment mustbesufficiently stable, andthenumber ofpulsesprocessed (forreducing antenna scanning modulation) mustbe sufficient toachievethislargevalueofimprovement factor. 
 Handbook," M. 1. Skolnik (ed.). 
 The  crossed-field amplifier (CFA) is often cathode-pulsed, requiring a full-power modulator. Some  CFAs are d-c operated, which means they can be turned on by the start of the RF pulse and  turned off by a short, low-energy pulse applied to a cutoff electrode. Some CFAs can be turned  on and off by the start and stop of the RF pulse, thus requiring no modi~lator at,itll. 
 The effects of flicker nois$a"e ov&@pe in the normal superheterodyne receiver by using  an intermediate frequen~y.high;khoight$ci.ender *, . !is the flicker noise small compared with the  normal receiver noise. Thisv. 
 Shmidman, “Generalized radar clutter model,” IEEE Trans. on Aerosp. Elec. 
 Instead, thephaseshiftersofasinglefeedprovide theazimuth steering whiletheMfeedsat eachcolumn provide theelevation steering. Intheseries-series planararrayallseriesphase shiftersintheelevation planetakethesamevalueandallseriesphaseshiftersintheazimuth planetakethesamevalue.Thusonlytwocontrolsignalsarerequired. Thesteeringcommands aresimplified attheexpense ofM - Iadditi.onal phaseshiftersandtheaddedlossofaseries arrangement. 
 IEEE , vol. 79, pp. 1538–1550, 1990. 
 The aircraft carrier–based E-2D aircraft (Figure 3.1) uses AEW radar as the primary   sensor in its airborne tactical data system. These radars with their extensive field of  view are required to detect small airborne targets against a background of sea and  land clutter. Because their primary mission is to detect low-flying aircraft, they cannot  elevate their antenna beam to eliminate the clutter. 
  6 AND ( n           
 However, the expected benefit may not be realizable unless jitter and noise during the starting time of each pulse are low enough, and these characteristics vary considerably among the different types of stabilized magnetrons. Common Problems. The classic problems of magnetron operation still exist, but they now tend to be better understood, specified, and controlled. 
 TION AND ANTENNA SIDELOBE LEVELS  A SECOND 
 Imperatore, P .; Pepe, A.; Lanari, R. Spaceborne Synthetic Aperture Radar Data Focusing on Multicore-Based Architectures. IEEE T rans. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 24.44  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 150 km from the radar. 
 BISTATIC RADAR  23.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 For example, when the target is surrounded on three sides by a receive site, a  transmit site, and another receive site such that a = 90º, sdr = scr = 1. This geometry  represents the optimum case of a unity GDOP factor, yielding a circular error ellipse  with radius equal to the range error of one transmit-receive pair. In contrast, when the  target is located some distance from the three sites, a is reduced. 
 9.Cutler.CC:Parabolic-antenna DesignforMicrowaves, Proc.IRE, vol.35,pp.1284-1294. Novem­ her.1947. ~. 
 Because the pulsing rate  typically determines the sampling frequency for doppler quantities on a constant puls - ing rate radar, the unambiguous doppler frequency (Nyquist frequency) for a fixed  pulse-repetition-frequency (PRF) radar is given by  FNyq = ± PRF/2 (19.20) where PRF is the pulse repetition frequency. Simultaneously, the unambiguous range  interval is given by  Rc a=⋅2 PRF (19.21) TABLE 19.5  Attenuation Caused by Clouds or Fog Temperature = 0°C57 Attenuation, dB/km Visibility, m l = 1.25 cm l = 3.2 cm l = 10 cm   30 1.25 0.20 0.02   90 0.25 0.04    0.004   300   0.045    0.007    0.001 ch19.indd   12 12/20/07   5:38:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Whicker, L. R. (ed.):" Ferrite Control Components, vol. 
 Thus some  means should be included to inform the operator when the detection probability has been  lowered bccausc of the C17AR actiori.  It is better to incorporate in the design of a radar means for eliminating unwanted signals  before they eriter the ADT than to depend on CFAR to eliminate them. Examples of signal  processing techniques that eliminate unwanted signals without a severe penalty in detectability  include MTI for clutter echoes, the low sidelobe antenna and/or sidelobe cancelers for jam-  ming noise, and the sidelobe blanker or the prf filter for pulse interference. 
 204  tube, 191  Electromechanical phase shifters, 297-298  Electron-bombarded semiconductor (EBS)  device, 217 21 R  Electron gun, 201  Electronic counter-countermeasures, 542,  547 553  Elevated ducts, 453  Endfire array, 279  Engine modulations. 435  Envelope detector. 2:\. 
 ( .. ).σ πα 42 22  (21.7) ch21.indd   8 12/17/07   2:51:14 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Government Printing Office, \Vashington, D.C.. CHAPTER 2 THE lU.DAR EQUATION BY E.M.PURCELL The operation ofaradar setdepends onthe detection ofaweak signal returned from adistant reflecting object. The factors which control thestrength ofthesignal soreceived areclearly offirst importance indetermining the maximum range ofdetection ofagiven target bya specified radar set. 
 In this text, Pra will be taken as the reciprocal or Tra B = 111, unless stated otherwise. Some  authors 11 prefer to define a false-alarm number n'.r that takes account the number of pulses  integrated, such that n1 = n 1 /n. Therefore, caution should be exercised when using d ilTerent  authors' computations for the signal-to-noise ratio as a function of probability of detection . 
 3.11. Extended Surface Targets.’—In many cases the individual scatterers inacompound target are confined toarelatively thin layer, which can betreated asanextended surface target. Nearly allofthe signals received byairborne radar are from targets that fall into this classification. 
 Identification and recognition U. General utility Y. Surveillance and control   (both fire control and air control) V. 
 Electron., pp. 37-40, 1961. Reprinted in Barton, D. 
 AdI'QlJCt's illMicroll'£Ires. vol.4. Academic Press,NewYork,1969. 
 May. 1959. ·  lX. 
 Mostlow-noise receivers alsohavelessdynamic rangethanonewitha· mixerfront-end. Sincethejammerpowerreceived attheradarvariesinversely asthesquareofthedistance between radarandjammer (one-way propagation), whiletheradarechopowervarieswith distance inversely asthefourthpower(two-way propagation), therewillbesomedistance belowwhichtheradarechowillexceedthejammer signal.Thisiscalledthest'~rscr('etlitlg ratlge,orthecrossover range,andisapproximately R2_P,rGraBjJ $I- -------PoGj41tBrS(14.2H) whereP,r=radartransmitter power J>,j=jammer transmitter power Gr=radarantenna gain Gj=jammer antenna gain a=targetcrosssection Bj=jammer bandwidth Br=radarsignalbandwidth J/S=jammer-to-radar signal(power) ratioattheoutputoftheIFrequired tomaskthe radarsignal Ajammer locatedonatargetofcrosssectionawilloverpower theradarifthejammer isata rangeRssorgreater.. OTHER RADAR TOPICS 551  A radar equation for detecting a target in the presence of jamming noise large compared  to receiver noise can be derived by substituting the jammer noise power per hertz received at  the radar for the receiver noise power per hertz, or kT, F,. 
 14.3 AIR-SURVEILLANCE  RADAR^' 29.46 49,103  The first successful application of radar was for the detection and tracking of aircraft. Air  surveillance continues to be one of the more important radar applications for both civilian  (air traffic control) and military purposes. The military employ such radars for general hurveil-  lance of the airspace, for providing acquisition information to anti-air-warfitre systems, and for  directing aircraft to an interception. 
 BASED SITES 4HE LATTER GROUP ARE NORMALLY KNOWN AS  VESSEL TRACKING SERVICE 643 o  RADARS 2ADARS ARE AVAILABLE FOR  LEISURE CRAFT  FISHING VESSELS AND MERCHANT SHIPS  AND ALL OPERATE EITHER IN THE  '(Z OR  '(Z BANDS -ANY NAVIES ALSO USE STANDARD OR SPECIALLY MODIFIED #-2 FOR NAVI 
 PLER SPECTRUM #OHERENT BEACONS WHICH RECEIVE  AMPLIFY  AND TRANSMIT RECEIVED RADAR PULSES  CAN PROVIDE A DOPPLER 
 Thepassivediode-limiter alsofindsimportant application whenusedwith aradioactive-primed gastubeTR.Thecombination isknownasapassiveTR-limirer. The passiveTR-limiter protects thereceiverfromnearbytransmissions evenwhentheladarisshut offsinceitrequires noactivevoltages foreithertheradioactive-primed TRtubeorthediode limiter.Thepresence ofthediodelimiterfollowing theTRtubeconsiderably reducesthespike leakage, increasing thelifeofthedeviceitselfaswellasthereceiverfronl-end itissupposed to protect.ThepassiveTR-limiter, however, hasahigherinsertion lossthantheTRtubebutit generates noexcessnoisebecauseitdoesnotemployakeep-alive discharge. Itsrecovery time issuperior totheconventional TRtube,butinferiortothediodelimiteractingaloneorthe ferritediodelimiter.40 ThepassiveTR-limiter haslowleakage overawiderangeofinputpower.Asan example,40 below1mWpeakpowertheoutputpowerislinearlyrelatedtotheinputpower. 
 This display has been used inair-to-air homing (AX/APS-6). The“Radial TimeBase”Indicator.-The radial-time-base indicator isathree-dimensional display which, like thedouble-dot display, isbeat. SEC. 
 Image-Reject Mixer. The single-ended mixer has two input responses which are derived from the square-law term in the power series. The responses occur at points above and below the LO frequency where the frequency separation equals the IF. 
 Tol- erable limits are shown in Table 15.4, but these limits may be loosened if coho locking is based on an effective average of the transmitter frequency during the pulse length. For an amplifier chain, pulse-to-pulse phase stability depends on HVPS ripple, and intrapulse phase variations depend on droop and ringing; tol- erable limits are also shown in Table 15.4. An interesting compromise is also feasible: if a locked coho is used with an amplifier chain, then pulse-to-pulse phase variations in the chain are not signifi- cant (except on second-time-around clutter). 
 The unwanted  signals include:  1. The reflection of the transmitted signals at the antenna caused by impedance mismatch.  2. 
 In case of failure of one channel, the radar can be operated as a scan-on-receive-only conical-scan radar with essentially the same performance as a conical-scan radar. The advantage of two channels with opposite-sense angle-error information on one with respect to the other is that signal fluctuations in the received signal areMIXER LO MIXER LO MIXERBANDPASSFILTER *1MIXER IFAMPLIFIER HARDLIMITER BANDPASSFILTER *2PHASE-SENSITIVEDETECTOR AMPLITUDEDETECTOR . TOANGLESERVOS FIG. 
 [ CrossRef ] 10. Jalilvand, M.; Li, X.Y.; Zwirello, L.; Zwick, T. Ultra wideband compact near-ﬁeld imaging system for breast cancer detection. 
 in J. Appl.  Phys., January, 1954. 
 13.4 magnetic field inthe same direction asthe magnetic axis ofthe trans- mitter rotor coil. There will beinduced inthe receiver rotor avoltage proportional toVsin(t%–%)where 131and 02arethe respective orien- tations ofthetwo rotors. Ifthereceiver isprovided with asecond rotor coil orthogonal tothe first, itwill experience avoltage proportional to Vcos (0,–e,). 
 “ The indicator was soarranged that itsdisplay was projected into the reflector sight, enabling the gunner tousethe same technique foreither optical orradar tracking. This equipment became available solate in the war that ithad substantially nooperational use, but itsproving- ground tests indicated that itsperformance would have been quite satis- factory. The attainable angular accuracy was about +0.5°. 
 436 THERECEIVING SYSTEM—RADAR RECEIVERS[SEC. 122 .=! r--l &lj m:r-----. SEC. 
 47. Dax, P.R.: Keep Track of that Low-Flying Attack, Microwaves, vol. 15, pp. 
 TO 
 The radiation pattern of an array may be shaped by modify- ing the aperture distribution. Good pattern approximations can be obtained by using phase only. In particular, the beam may be broadened by applying a spher- ical phase distribution to the aperture or by approximating it with a gable (trian- gular) phase distribution. 
 FUNCTION RADARS ARE TYPICALLY CAPABLE OF UTILIZING WAVEFORMS FROM THE VARIOUS 02& CATEGORIES IN ORDER TO CARRY OUT THEIR DIVERSE MISSIONS 0ULSE $OPPLER 3PECTRUM  4HE TRANSMITTED SPECTRUM OF A PULSE DOPPLER RADAR CON 
 Arguing that such comprehensive calculations are excessive when there are  significant uncertainties in the electron density distribution, NRL Memorandum  Report 2500152 describes the basic technique used for path determinations. A simple  closed-form virtual path trace, Snell’s law for a spherically symmetric medium,  is sequenced through elevation radiation angles in 1 ° increments. This process is  incremented in 1-MHz steps over the radar’s operating band. 
 Eng., vol. OE-Il, pp. 196-210, April 1986. 
 74.Quigley. A.L.c.:Tracking andAssociated Problems. Internatiollal Colit:OilRadar-···Pr/:'sellt alld FJ/t/l/'t'.Oct.2325.19D.London. 
 The deionization process can be speeded up by the  addition of water vapor or a halogen. The life of TR tubes filled with a mixture of a noble gas  (argon) and a gas with high electron affinity (water vapor) is Jess than the life of tubes filled  with a noble gas only.  To ensure reliable and rapid breakdown of the TR tube upon application of the RF pulse,  an auxiliary source of electrons is supplied to the tube. 
 . Radar System Engineering  Chapter 9 – Synthetic Aperture Radar  71     9 Beamforming      Figure 9.1  Beamforming concepts.         Figure 9.2  Single channel Phased Array. 
 The  attenuation by precipitation is a function of precipitation intensity  and wavelength. For atmospheric gases, it is a function of  elevation angle, range, and wavelength. Since all of th is is  taken in account for e.g. 
 Sutherland. J. W.: Marconi S600 Series of Radars. 
 42–43, January 17, 2005. 90. F. 
 GENERATION AIR TRAFFIC CONTROL !4#  RADAR  AS PART OF THE -ULTI 
 MEDIUM 02& WAVEFORMS USUALLY USE MULTIPLE DISCRETE 02& RANGING TO RESOLVE RANGE AMBIGUITIES  WHILE LINEAR &- RANGING IS COMMONLY EMPLOYED WHEN HIGH 
 contained inthetwo-way pathbetween theradarandthetarget is2RjA..ThedistanceRandthewavelength), areassumed tobemeasured inthesameunits. Sinceonewavelength corresponds toanangular excursion of2nradians, thetotalangular excursion cPmadebytheelectromagnetic waveduringitstransittoandfromthetargetis 4nRj).radians. Ifthetargetisinmotion,RandthephasecParecontinually changing. 
 The  succeeding stage must also have a small noise figure, or else the gain of the first stage must be  high enough to swamp the noise of the succeeding stage. if the first network is not an amplifier  but is a network with loss (as in a crystal mixer), the gain GI should be interpreted as a number  less than unity.  The noise figure of N networks in cascade may be sbwn to be  Similar expressions may be derived when bandwidths and/or the temperature of the individual  networks aremot the same.3  Noise temperature. 
 Pierson and Moskowitz have derived the following relation for a fully developed spectrum based upon empirical data.20 . (b) FIG. 24.2 (a) Ocean-waveheight power spectral density (PSD) is given as a function of water- wave frequency. 
 The last paper [ 19] of this special issue concerns SAR imaging of oceanic eddies generated by shear-waves. The authors developed a method for simulating the current ﬁeld of an ocean eddy according to the Burgers–Rott vortex model. These simulated ocean eddies were then used to generate SAR images through a simulation tool. 
 However, the direct signal can serlo~isly  interfere with the measurement of the angle of arrival, just as does a multipath signal. To  extract the angular location of the target, the direct signal must be separated in some manner  from the target signals. This is not an easy task since the angles of arrival of the direct anti  scattc~.cd sig~lals are generally close to one anotller wllen tlie histatic radar is alru~igod lo  provide fence coverage. 
 DOPPLER SPACE IS BROKEN UP INTO A GRID OF RANGE BINS AND DOPPLER FILTERS  AS  SHOWN IN THE FIGURE %ACH CELL IN THE GRID MIGHT BE  ¾  RANGE 
 The standing-wave pattern on the cable feeding the reference signal to the receiver, due to  poor mixer match .  . l The leakage signal entering the receiver via coupling between transmitter and receiver  antennas. 
 pp.121-124, January, 1954. 84.Taylor,TT:DesignofLine-source Antennas forNarrow Beamwidth andLowSideLohes,IRE TrailS.,vol.AP-3,pp.16-28,January, 1955. 85.Hansen, R.c.:GainLimitations ofLargeAntennas, IRETrailS.,vol.AP-8,pp.490-495, Seplc:=mha, 1960. 
 9.7  9.6 Antenna-Related ECCM  .........................................  9.7  Sidelobe-Blanking (SLB ) System  .......................  9.9  Sidelobe Canceler (SLC ) System  ....................... 
 Diode Phase Shifters.87–90 Diode phase shifters are typically designed by using  one of three techniques: (1) switched-line, (2) hybrid-coupled, and (3) loaded-line.  These are shown diagrammatically in Figure 13.34. The switched-line technique sim - ply switches in lengths of line in binary increments (e.g., 180 °, 90°, and 45 °) and  requires a set of diodes for each bit. 
 SYNCHRONOUS ORBITS AT  ^ KM ALTITUDE 4HE RADARS  MASS IS ^ KG 3!2 
 Y . Bar-Shalom and T. Fortmann, Tracking and Data Association , Orlando, FL: Academic Press,  1988. 
 It is also important to understand the effect of the ground scattering coef - ficient and the topography when interpreting echoes from targets above the ground. Sea Clutter.  In contrast with the abrupt changes in scattering behavior that  occur at coastlines or over complex terrain, the magnitude of the radar echo from  the open ocean, that is, the scattering coefficient s ° tends to vary slowly with range  and azimuth as a consequence of the scale lengths of typical oceanic meteorological  systems and the response time of the ocean surface to varying wind stress. 
 GAIN REPEATER JAMMER HAS THE EFFECT OF CAUSING POSITIVE FEEDBACK  WHICH PUSHES THE TRACKING 
 1976.  82. L.cili-lispcriscii. 
 Ahlockdiagram oftheanglc-tracking portionofatypicalconical-scan tracking radaris showninFig.5.3.Theantenna ismounted sothatitcanbepositioned inbothazimuth and elevation byseparate motors, whichmightbeeitherelectric-orhydraulic-driven. Theantenna beamisoffsetbytiltingeitherthefeedorthereflector withrespecttooneanother. Oneofthesimplest conical-scan antennas isaparabola withanoffsetrearfeedrotated abouttheaxisofthereflector.Ifthefeedmaintains theplaneofpolarization fixedasitrotates, itiscalleda1Itltatillg feed.Arotating feedcausesthepolarization torotate.Thelattertypeof feedrequires arotaryjoint.Thenutating feedrequires aflexiblejoint.Utheantenna issmall,it maybeeasiertorotatethedish,whichisoffset,ratherthanthefeed,thusavoiding theproblem ofarotaryorfiexibleRFjointinthefeed.Atypicalconical-scan rotation speedmightbe 30r/s.Thesamemotorthatprovides theconical-scan rotationoftheantenna beamalsodrives at\\oJ-phase reference generator withtwooutputs90°apartinphase.Thesetwooutputsserve asareference toextracttheelevation andazimuth errors.Thereceived echosignalisfedtothe receiver fromtheantenna viatworotaryjoints(notshownintheblockdiagram). 
 Although they may not always be thought of as radars, the radio  altimeter (either FM/CW or pulse) and the doppler navigator are also radars. Sometimes  ground-mapping radars of moderately high resolution are used for aircraft navigation  purposes.  Ship Sa(ety. 
 02/ VERSION   HTTPWWWSPACEWCOMWWWPROPLABHTML  " 4 2OOT AND * - (EADRICK  h#OMPARISON OF 2!$!2# (IGH 
 74.4 SOURCES Master Oscillator Power Amplifier (MOPA) Chains. Requirements peculiar to CW radar are the use of extremely quiet tubes throughout the transmitter chain, very quiet power supplies, and, often, stabilization to reduce the total noise of the system. In theory, any of the methods for measuring FM and AM noise to be discussed in Sec. 
 Trial Report No. 44/24, 3rd April 1944 (TNA AIR 65/92) [13] Performance of A.S.V. Mk. 
 REACHING CONSEQUENCES 4HE  THEORETICAL SINGLE 
 AMPLITUDE !PPROXIMATION  )N THE LIMIT OF SMALL RATIOS OF RMS WAVEHEIGHT TO  RADAR WAVELENGTH OR  MORE SPECIFICALLY    KH       ONLY THE FIRST TERM IN THE SERIES IN %Q  SURVIVES  AND THE CROSS SECTION ASSUMES  THE VERY SIMPLE FORM   SY P Y Y     C O S   `K& 7 KP    .   3%! #,544%2  £x°Ó WHERE THE CONSTANT  ! HAS BEEN MADE EXPLICIT AND  &P HAS ABSORBED A SIN TERM FROM THE  SERIES 7  IS THE &OURIER TRANSFORM OF THE SURFACE CORRELATION FUNCTION  WHICH MAKES  IT THE SEA WAVENUMBER SPECTRUM DISCUSSED IN 3ECTION   EVALUATED AT TWICE THE  SURFACE 
 NADIR   LOOK ANGLE OF CERTAIN 3"2S  CAN BE ADJUSTED TO INCREASE THE EFFECTIVE REVISIT RATE .OTE THAT ORBIT MANEUVERS ARE NOT A PRACTICAL MEANS TO IMPROVE THE FREQUENCY OF SITE COVERAGE  SINCE A LARGE CHANGE IN ALTITUDE HENCE VELOCITY   OR ESPECIALLY ANY CHANGE OF ORBIT INCLINATION THE ANGLE OF  THE INERTIAL ORBIT PLANE WITH RESPECT TO THE %ARTHS EQUATOR   WOULD REQUIRE A SUBSTANTIAL  EXPENDITURE OF PRECIOUS ONBOARD FUEL RESOURCES  4HE %ARTH IS FLATTENED AT THE POLES  DUE PRIMARILY TO ITS RELATIVELY RAPID ROTATION 4HE  RESULTING LACK OF SPHERICAL SYMMETRY IN THE GRAVITY FIELD AT ORBITAL ALTITUDE IMPOSES SMALL LATERAL FORCES ON AN INCLINED ORBIT PLANE  WHICH CONSEQUENTLY PRECESSES IN INERTIAL SPACE 4HE AMOUNT  DIRECTION  AND RATE OF ORBIT PRECESSION CAN BE CONTROLLED BY CHOICE OF THE INCLINATION AND THE MEAN ALTITUDE OF THE ORBIT -ANY SATELLITE PLATFORMS USE THIS DEGREE OF FREEDOM TO GENERATE A SUN 
 BILITIES  POWER SUPPLY RIPPLE AND NOISE   F NOISE  TIMING JITTER  AND UNWANTED MIXER  PRODUCTS DISCRETES OR  SPURS  -ULTIPLICATIVE NOISE MODULATES  RADAR RETURNS BY VARYING  THEIR AMPLITUDE OR PHASE AND IS PRESENT ON ALL RADAR RETURNS BEING MOST APPARENT ON LARGE RETURNS SUCH AS MAIN 
 These ﬁrst airborne radars were quite primitive by modern standards but made an immediate impact onthe conduct of naval warfare. Over the next ﬁve years of war there was an extraordinary development in technology, both in the UK and in the USA. ASV went from simple systems operating at VHF through to complex microwave radars. 
 84 restricted scope. Mention should bemade, however, ofthemore general problem ofidentification, which gave rise toasystem known asIFF— Identification ofFriend orFoe. This system was probably the most important single field ofapplication ofradar beacons inthe war. 
 MODULATED CARRIER AND THE  n 
 13 it was implied that knowledge of radar clutter  characteristics at microwaves was less than desired. There is even less information on clutter at  frequencies above 10 GHz. Details will not be given here, but the general trends will be  summarized for the several types of clutter that have been measured. 
 2.6 PATTERNPROPAGATIONFACTOR The pattern propagation factors Ft and Fr in the range equation account for the facts that (1) the target may not be in the beam maximum of the vertical-plane antenna pattern and (2) non-free-space wave propagation may occur. This single factor, rather than two separate factors, is designed to account for both of those effects. This is necessary because they become inextricably intertwined in the calculation of multipath interference, which is the most important non-free-space effect. 
 Spetner, L. M.: Incoherent Scattering of Microwaves from the Ocean, Radio Science, vol. 10,  pp. 
 Guide to Convolutional Neural Networks: A Practical Application to T rafﬁc-Sign Detection and Classiﬁcation ; Springer: Heidelberg, Germany, 2017. 28. Lawrence, S.; Giles, C.L.; Tsoi, A.C.; Back, A.D. 
 Hodgens: Propagation of'Millimeter and Submillimeter Waves, U.S. Anny  Missile Research and Der·elopment Command. Tec/1. 
 TIONS CAUSED BY THE TARGET ONLY  EXCLUDING ATMOSPHERIC EFFECTS AND RADAR RECEIVER NOISE CONTRIBUTIONS  ARE CALLED TARGET NOISE. 
 Solid-state devices, suchastransistors andmicrowave diodegenerators, havealsobeenconsidered forradaroperation. Theirproperties differsignificantly from .../ microwave tubesandrequiremajorchanges insystemdesignphilosophy whentheyareused. 6.2THEMAGNETRON OSCILLATOR Morethananyothersingledevice, thehigh-power magnetron oscillator invented in 19392madepossible thesuccessful development ofmicrowave radarduringWorldWarII. 
 The median detector is "robust," in that the threshold values  and the detection probabilities do not depend on the detailed shape of the clutter pdf, but only  on the median value.  The conventional receiver may be considered as comparing the 111ra11 value of the II pulses  to a predetermined threshold. Trunk has shown that the trimmed-mean detector ~an be better  than either the mean or the median detectors.26·27 If there are II pulses available from which to  make a detection decision, the trimmed-mean detector discards the smallest and the largest of  the II pulses berore· taking the mean. 
 The research organisations also continued to evolve. In 1953 TRE was merged with the British Army ’s Radar Research and Development Establishment (RRDE) to become the Radar Research Establishment (RRE). In 1957 its name was further changed to the Royal Radar Establishment, also RRE. 
 These  errors typically cause pattern grating lobes because these  error cusps are normally several wavelengths apart.   The grating lobes are easily recognizable based on their −4−3.5−3−2.5−2−1.5−1−0.50 0 0.01 0.02 0.03 0.04 0.05 0.06 Roughness, ε/λLoss in dB FIGURE 12.10  Surface roughness, e/l, vs. loss FIGURE 12.11  Systematic dis - placement between supports with  a cusp between supports ch12.indd   13 12/17/07   2:31:17 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 If the radar is to perform wide-area surveillance, frequent frequency changes are  required in order to cover the various range extents. In addition, relative phase or time- delay changes are required in each amplifier chain to accomplish azimuthal steering.  A broad-bandwidth performance and a tolerance to a variable voltage standing-wave  ratio load are, therefore, essential features in an HF radar transmitter. 
 HALF OF THE INCIDENT WAVELENGTH  IE  TO BE OF THE "RAGG TYPE  2EINFORCED BY THE THEORETICAL IMPLICATIONS OF VARIOUS SMALL  WAVEHEIGHT APPROXIMATIONS AND WAVE 
 Thesis, University of Karslruhe, Karslruhe, Germany, 2001; pp. 15–43. 15. 
 SPEED ANALOG 
 3.2. Example 2: The Experimental Validation Using ERS-2 SAR Image To further verify the feasibility of the method, we performed a similar simulation experiment of an ERS-2 SAR image. Figure 8is an ERS-2 SAR image acquired in the Luson Strait, on 11 June 2010 at 01:25:47 UTC. 
 Any use is subject to the Terms of Use as given at the website. Meteorological Radar.  METEOROLOGICAL RADAR  19.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 for quantitative precision in interpreting the weather echoes. Modern weather radars  require large dynamic range to sense strong echo at short range and weak echo at  long range. 
 A. Scheer and J. L. 
 CONTROLLED TUBES  SOLID 
 Kerker, M., M. P. Langleben, and K. 
 The in-plane Domville land clutter data can be divided into three regions: a low-grazing-angle region, where 0, < ~ 3° or 6, < ~ 3°, the hatched area in Fig. 25.10; a specular-ridge region, where 140° < (8, + 6,) < 220°, the dotted area; andFORWARDSCATTER (0J^O0, 0S«180°) SPECULAR-RIDGE REGION BISTATIC SCATTER REGION LOW-GRAZING-ANGLE REGIONSPECULARRIDGE (0; +0S^180°)0B (DEGREES) 0j (DEGREES)MONOSTATIC (0i = 0S) . a bistatic scatter region, where (S1-, 0J assume values shown as the shaded areas in Fig. 
 1975.  128. Schwartzman. 
 CONTROLLED TUBES ARE CAPABLE OF HIGH POWER  WIDE BANDWIDTH  GOOD EFFICIENCY  AND INHERENT LONG LIFE  BUT THEY ARE OF LOW OR MODERATE GAIN 4HEIR CHIEF LIMITATION IS THAT THEY ARE NOT CAPABLE OF OPERATING AT HIGHER FREQUEN 
 Both the loss in  performance and the difficulty in obtaining large isolations have limited the application of the  hybrid junction to short-range radars.  Ferrite isolation devices such as the circulator do not suffer the 6-dB loss inherent in the  hybrid junction. Practical devices have isolation of the order of 20 to 50 dB. 
 LECTION OF DISCRETE PATCHES  AS SUGGESTED IN &IGURE  4HE PATCHES MUST BE SMALL ENOUGH TYPICALLY LESS THAN  K  THAT THE UNKNOWN CURRENTS AND CHARGES OVER EACH PATCH  ARE CONSTANT OR AT LEAST CAN BE DESCRIBED BY SIMPLE FUNCTIONS ! WEIGHTING FUNCTION MAY BE ASSIGNED TO EACH PATCH  AND THE PROBLEM IS ESSENTIALLY SOLVED WHEN THE AMPLITUDE AND PHASE OF THOSE FUNCTIONS HAVE BEEN DETERMINED )F THE POINT OF OBSERVATION IS FORCED DOWN TO A GENERAL SURFACE PATCH  THE FIELDS ON  THE LEFT SIDES OF %QS  AND  ARE THOSE DUE TO THE CONTRIBUTIONS OF THE FIELDS ON ALL OTHER PATCHES  PLUS THE INCIDENT FIELDS AND A hSELF 
 The beam  may be scanned by positioning a single feed anywhere on the surface of the lens or by locating  many feeds along the surface of the sphere and switching the radar transmitter or receiver from  one horn to another. The Luneberg lens can also generate a number of fixed beams.  The index of refraction q or the dielectric constant c varies with the radial distance in a  Luneburg lens of radius r,, according to the relationship  The iadex of refraction is a maximum at the center, where it equals fl, and decreases to a  valuc of 1 on the periphery. 
 The visibility of eddy spirals under two parallel look directions is also the same and the spirals are more obvious under radar look directions of 0◦or 180◦. SAR images simulated under different wind ﬁelds show that wind direction and wind speed mainly affect the SAR imaging of the whole eddy area. Wind direction affects the brightness variations throughout the SAR image, and half of the image with the current ﬁeld direction opposite to the wind direction is brighter, whereas the other half is darker. 
 Farina, A., and E. Hanle: Position Accuracy in Netted Monostatic and Bistatic Radar, IEEE Trans., vol. AES-19, pp. 
 TheRayleigh prohabilily t1ensityfunctioll aswasgiveninSec.13.3is I'>(} (lJ.J(}) whererr2isthemeansquarevalueof1'.TheRayleigh pdfhastheproperty thattherms amplilude oftheIluctuations aboutthemean(t1enoted by(5Ilin)isproportional tothemeanf'in. or(5"ln=kl\n'Alogarithmic receiverhasthecharacteristic 1'0111=IIloghVin Theslopeofthelogarithmic receivercharacteristic atVinis ~I'OUI II ~I'in Vin(13.31) (13.32) Iftheinputclutterfluctuations (h'inaresmallcompared tothetotalrangeofthelogarithmic characteristic. theOlitPUtIluctuations (5vOIIIarcapproximately II (51'0111=slopex(51'in=_()Vin=ak Vin(13.33) Thustheoutputfluctuations areconstant, independent oftheinputmean. 
 &- ,&-  WAVEFORM SEE 3ECTION  OF #ARRARA    AND IS SELDOM USED ,INEAR 
 SENSING ALTIMETERS 4HESE COMMENTS ARE ELABORATED IN 3ECTION  !S DISCUSSED IN SEVERAL CHAPTERS OF THIS BOOK  THE PERFORMANCE OF DOPPLER 
 This action is cumulative, and the master-condenser  C therefore discharges rapidly through Vé until, when it  becomes discharged, no further current flows through  Rb. Then the cycle repeats. The value of Rb affects  the amplitude of the triggering pulse present in the grid  circuit of Vc, and also modifies the flyback period due to  its presence in the discharging path, and this, of course,  provides us with a trigger control. 
 NOISE AMPLIFIERS  DUPLEXERS  SWITCHES  AND CONTROLS TO ENABLE ON 
 SCAN PROBABILITY OF DETECTIONS IS STARTED AT A RANGE WHERE THE TARGETS  0D SS  IS APPROXIMATELY  4HERE IS AN OPTIMAL SEARCH FRAME TIME FOR  CUMULATIVE DETECTION  PERFORMANCE ! BALANCE MUST BE ACHIEVED ! SHORT FRAME TIME LIMITS THE AMOUNT OF  ENERGY PLACED ON TARGET PER DWELL AND LOWERS THE SINGLE 
 79, pp. 791–799, 1991. 15. 
 Probert-Jones, J. R.: The Radar Equation in Meteorology, Q. J. 
 THERMAL 
 In terms of the effective bandwidth. the time-delay error becomes  I  ,n~ = //(2E/No)i1i (11.17)  and the range error is ()R = (c/2) f>1~.  The effective bandwidth as defined hy Eq. 
 A,. K. E. 
 The CPR’s high-power amplifier (HPA) is the first of its kind for a space-based  radar, an extended interaction klystron.155 The klystron is driven by 200 mW signals  from a solid-state preamplifier. The klystron requires 20 kV , provided by a high-voltage  power supply system that also is a space first. The HPA is fully redundant. 
    #ANADA         # ((%23 
 Spurious doppler spectra levels are dictated by requirements to suppress clutter interference through doppler filtering. Harmonics are generated by any component which is nonlinear at the power level created by the transmitter and which passes those harmonics to the an- . tenna. 
 East ofTokyo isFunabashi, astrong signal atthe head ofTokyo Bay. Numerous small towns intheKanto plain areshown asindividual arcs, particularly tothe west ofthe aircraft. The Tone River isvisible just below the N FIG, 3.29.—Small towns near Worcester, Mass. 
 DOMAIN WEIGHTING REDUCES THE PEAK TIME SIDELOBE LEVEL FROM n D" TO n D" WITH AN INCREASE IN THE  
 46 TRANSMITTERS  A HIGHLY COMPETITIVE INDUSTRY CONCERNED WITH COST )T HAS BEEN SAID THAT IN 5(& 
 INTERACTION STRUCTURE CONSISTED OF A CYLINDRICAL ARRAY OF  ESSENTIALLY INDEPENDENT GROUNDED 
 In the HF skywave  radar case, the inevitability of Faraday rotation that occurs during ionospheric propa - gation has been used to argue that a fully polarimetric treatment is unnecessary, so it  is common practice to represent the scattering behavior in terms of scalar radar cross  section (RCS). Fully polarimetric formulations are relevant when modeling complex  scattering processes69,70 and for target classification studies.71 In general, aircraft and ships have dimensions that put them within the resonant  scattering regime, though the smallest aircraft and cruise missiles will lie in the  Rayleigh scattering regime for the lower half of the HF band. Here, the RCS displays  limited aspect sensitivity and a strong dependence on the target’s gross dimensions. 
 In practice Gee can  use three transmitters, A being related both to B and C.  On the Gee tube in the aircraft transmissions from these three  stations are seen as spikes of light on the trace.  (Left to right, below.) The Gee receiver time-base is adjusted  to align the ‘blips’ in relation to the strobe. 
 Helical radiating elements have also been used in arrays to obtain phase shift~ by rotation of  the elements.62  A change in phase in the waveguide transmission may be obtained by mechanically  changing the dimensions of the guide.20•59 One such device that has been applied to practical  radars is the Eagle scanner, or delta-a scanner. The latter term is descriptive of the fact that the  velocity of propagation, and therefore the phase, of a signal propagated through a waveguide  depends on the width of the guide, or its "a" dimension. This phase shifting technique has  been used for GCA (ground control approach) radars to mechanically scan fan beams in  azimuth and elevation. 
 48. W. D. 
 Barrick, D. E. Normalization of Bistatic Radar Return, Ohio State University, Res. 
 H.: Tracking of Formation Flying Aircraft. I~rternational Conference RADAR-77, Oct. 25-28,  1977. 
      . 
 The circuit issoarranged that the 180° shift inphase oftheaudio signal pro- duces phase agreement, thereby providing pulses ofplate current on alternate half cycles oftheaudio signal. These pulses, further amplified inVs,then trigger thyratron V4tostop thesweep. The change from search tobeacon operation isperformed remotely byrelays which switch the grid input toV~, switch from the reflector voltage-control potentiometer PItoPz, change over the plate power from thesearch tothebeacon local oscillator, and superpose thesinusoidal modulation onthesawtooth. 
 L. Frank, “Polyphase codes with good nonperiodic correlation properties,” IEEE Trans .,   vol. IT-9, pp. 
 Theseawasdeveloped bya25-lI.not approaching .....ind.Radarfrequency was .13.4MHzproducing .1resonant doppler frequency shiftof0.37HI.Thedoppler frequency scalehashecn Ilormaltzed sothattileJominant components areat±I.ARW=approach resonant wave;RRW= recederesonant wavecalibration signalisatleftoffigure. isnotfoundatzerofrequency asisthecaseforlandbackscatter, butiscentered attwodiscrete frequencies symmetrically spacedaround zero,Fig.14.8.Theseamaybethought ofas composed ofalargenlJmberofindividual wavetrains,eachwithadifferent wavelength and ampli~ude andtraveling indifferent directions. Thiscollection ofwavetrainsisdescribed bya two-dimensional spectrum (waveamplitude asafunction ofwater-wavclength anddirection or travel).Atgrazing incidence theradarresponds chieflytothetwowavetrainswhichare traveling towardandaWJVfromtheradar,eachwithawater-wavelength Awequaltohalfthe radar-wavelength Ar.Foritgrazingangle4>,thiscondition becomes Aw=(J..r/2)cos4>.The scattering fromthesetwo..resonant" wave component~ issimilartothatfromadiffraction grating. 
 FALL SPEED DATA OF 'UNN AND +INZER  THE RAINFALL RATE CAN ALSO BE OBTAINED  AND : RELATED TO  2 AS SHOWN IN %Q  4HE EXPONENTIAL FORM OF THE DROP 
 The result of the proposed method is still better than the DCT and PGA method results. 289. Sensors 2019 ,19, 1154      (a) (b)       (c) (d)  Figure 16. 
               
 Tlie STC action should be in the RF portion of the receiver rather than in the  logarittimic amplifier.  RADAR CLUTTER 507 tionoftargetsinseac1utter.RR.HQitisprohahly moreusefulforoperation inprecipitation clutter.SuchclutterismorelikelytoheRayleigh thanse,tclutter(Sec.13.3)orlandclutter (Scc.13.5)thatortcncxhibitnon-Rayleigh characteristics. espccially withhigh-resolution radar.Thelog-FTC hassometimes heencalledwelltlrerfix. 
 Most  cameras produce separate images that are approximately square. Strip film cameras  and optical-infrared scanners produce strip images like those of radars, but with differ - ent distortions because they are angle-, not range-, measuring devices. Every pure and applied science that uses aerial photography can also use radar  images. 
    
 349-357, 1966. 59. Seliga, T. 
 Angle ^ 1 deg.* = Noise . Loss (dB) Frequency (MHz) or El. Angle (deg) Noise (dBW) Lx>ss (dB) Frequency (MHz) or El. 
 $ RADARS WILL ALLOW MORE ACCURATE  PRECIPITATION MEASUREMENTS AND ICE 
 SQUARED PATTERN .OT ONLY DOES THIS COMPENSATE FOR THE USE OF 34#  BUT ALSO ENHANCES THE TARGET 
 3.8. In channel .4 the signal  is processed as in the simple CW radar of Fig. 3.2. 
 Figure 13. Time-series deformation results compared with leveling measurements on benchmarks: (a) BMK 4 in Figure 3a, and ( b) BMK 5. T able 3. 
 574 PRIME POWER SUPPLIES FOR RADAR [SEC. 146 to+10”C shall be390 to410 cps; over the same range ofvoltage and load, the frequency limits foratemperature range of–55°C to+70”C shall be380 to420 cps. Table 14.5 gives thefrequency range ofinverters now ingeneral use, and inthe column headed “Remarks” the motor type ormethod of speed control isindicated. 
 RELATION AND AMBIGUITY FUNCTION DEFINITIONS USED ARE SUMMARIZED IN THE !PPENDIX AT THE END OF THIS CHAPTER&)'52%    "LOCK DIAGRAM OF A BASIC PULSE COMPRESSION RADAR 
 Stiles, “The active and passive microwave response to snow parameters,  part II: water equivalent of dry snow,” J. Geophys. Res. 
 For a  pulse radar, the spectrum is sampled by the pulse repetition frequency (PRF). If the  PRF is high enough so that the entire spectrum can be reproduced (the PRF is higher  than the Nyquist frequency, 2 ∆fd), the diagram indicated is that of the spectrum of the  samples of a received pulse at a given range. Figure 16.11 shows a series of actual  pulses from a moving radar, followed by a series of samples at range R1. 
 http://mars.jpl.nasa.gov/mro/overview/ 4. http://www.jsfws.info/selene_sympo/en/text/overview.html 5. http://trmm.gsfc.nasa.gov 6. 
 The default  unit for peak power is Kilowatts. By right-clicking on the label associated with peak  power, you may select other units of input. AREPS will even convert the input number  automatically from one unit to the other unit. 
 For agiven transmitted power, thesignal discernibility isalways directly proportional tothe gain ofthe transmitting antenna. Atthe receiving station the signal-t o-internal-noise ratioisalso proportional tothe antenna gain. and considerable interference reduction isaccomplished bythedirection- ality that accompanies high gain. 
 P. Gogineni et al., “Application of plane waves for accurate measurement of microwave  scattering from geophysical surfaces,” IEEE Transactions on Geoscience and Remote Sensing ,   vol. 33, pp. 
 Adaptive Arrays, An adaptive array (Fig. 9.3) is a collection of N antennas, feeding a weighting and summing network, with automatic signal-dependent weight adjustment to reduce the effect of unwanted signals and/or emphasize the desired signal or signals in the summing network output. Output signal z is envelope-detected and compared with a suitable threshold a to detect the presence of a useful target. 
 The scan frequency also must be at least an order of magnitude greater than the  tracking bandwidth.  A conical-scan-on-receive-only (COSRO) tracking radar radjates a nonscanning transmit  beam, but receives with a conical scanping beam to extract the angle error. The analogous  operation with sequential lobing is called lobe-on-receive-only (LORO). 
 Hence the width of the gate should be sufficiently  narrow to minimize extraneous noise. On the other hand, it must not be so narrow that an  appreciable fraction of the signal energy is excluded. A reasonable compromise is to make the  gate width of the order of the pulse width. 
 Referring to ﬁgure 7.6, this suggests that ASV Mk. VI might be expected to detect Grassholm Island at 40 nmi and ASV Mk. VII is Figure 7.5. 
 This allows us to replace the  gradient of Green’s function with  ∇ =ψ ψikos (14.9)  ψ πoR o e e Ro =− ×ik ik rs/4  (14.10) where r is the position vector of integration patch dS and s is a unit vector pointing  from an origin in or near the object to the far-field observation point, usually back  toward the radar. Ro is the distance from the origin of the object to the far-field obser - vation point. The second is the tangent plane approximation , in which the tangential field com - ponents n × E and n × H are approximated by their geometric optics values. 
 E. Pellon, “A double Nyquist digital product detector for quadrature sampling,” IEEE Trans.  on Signal Processing , vol. 
 Adt~nncc~s in hlic.ro~~art~s, vol. 4.  Academic Press, New York, 1969. 
 SEC. 922] STREA MLIA”ING 315 function, radome materials, transmission ofradar energy, structural requirements, aerodynamics, access tothe radome cavity, and specifica- tion and test. Inthis discussion only the three major items—aerodynamics, elec- trical transmission, and structural design—will bediscussed, and these only briefly. 
 TIME RECORD OF A SINGLE MEASUREMENT OVER A TARGET /NLY AMPLITUDE 
 n°Ón  2!$!2 (!.$"//+  n°{Ê *1 - 
 6.2 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 bandwidth at the IF frequency. These advantages have proven to be so significant  that competitive forms of receivers have virtually disappeared. In conventional antenna systems, the receiver input signal is derived from the  duplexer, which permits a single antenna to be shared between transmitter and  receiver. 
 1.2. Tlle transtnitter may be an oscillator, such as a magnetron, that is " pulsed"  (turned on and on) by the rnodulator to generate a repetitive train of pulses. The magnetron  has prohnhly been the most widely used of the various microwave generators for radar. 
 Now that radar employs very high  . 58 HOW RADAR WORKS  frequencies the normal transmission-line links are not  very efficient or practical, and it has been found possible  literally to ‘ pipe’ the transmitter and receiver to the aerial !  These midget wavelengths appear to travel almost without  loss through pipes or conduits of suitable shapes and  dimensions, and the conduits, which we call ‘wave-  guides,” are all part of the ordinary radar very-high-  frequency technique.  Now we come to the final link in our chain—the  magic eye with which we hope to display our received  echo, and gain operational information from its position. 
 18-26, IEEE Catalog no. 74 CHO 934-0 NEREM.  65. 
 E. Frezal, D. Vidal-Madjar, D. 
 AP-6, pp. 129-133, January, 1958.  36. 
 For most purposes, it is more convenient to deal with virtual height, because there are two theorems that  dramatically simplify practical calculations. Martyn’s theorem shows that complicated oblique skywave ray paths  via the true reflection point can be replaced to good approximation with simple rectilinear geometry via the virtual  reflection point. The theorem of Breit and Tuve demonstrates that, to good approximation, the time-of-flight is  unchanged by this substitution. 
 274-280, March, 1974.  61. Trunk, G. 
 PARAMETER THRESHOLD IS LARGER THAN THOSE ASSOCIATED WITH A ONE 
 A. W.: A Study of the Double Modulated FM Radar. Itrst. 
 W. Howells, General Electric Co., Heavy Military Electronics Depart­ ment, Syracuse, N. Y.) . 
 Andrews, G. A .. Jr.: Optimal Radar Doppler Processors, NRL Report 7727, Naval Research Labora­ tory. 
 Gens and J. vanGenderen, “Review article: SAR interferometry—issues, techniques, applica - tions,” Int. J. 
 For this reason, the range cells surround­ ing the test cell are often omitted when averaging the background. As mentioned in Sec. 5.10,  the resolution of targets in range is degraded by the adaptive threshold process. 
  RADAR  WHICH USED A VACUUM TUBE !LSO THE SOLID 
 TYPE CLOUDS IN DRY CLIMATES INDICATES THAT CONVECTIVE SHOWER RAINFALL PROFILES ARE MUCH MORE DIFFICULT TO MODEL !TTENUATION BY (AIL  2YDE  CONCLUDED THAT THE ATTENUATION CAUSED BY HAIL IS  ONE 
 34 Generalized reflector geometry ch12.indd   32 12/17/07   2:31:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 
 168-174, November, 1968.  54. Grasso, G.: Improvement Factor of a Nonlinear MTI in Point Clutter, IEEE Trans., vol. 
 The STC attenuator is followed by an RF amplifier, often referred to as a low-noise  amplifier (LNA). This amplifier provides sufficient gain with a low noise figure to  minimize the subsequent degradation of the overall radar noise figure by subsequent  components. If sufficient gain is provided in the antenna prior to the receiver, it may  be possible to eliminate this gain stage. 
 At the other end of the spectrum, millimeter radars  have operated at 94 GHz. Laser radars operate at even higher frequencies.  The place of radar frequencies in the electromagnetic spectrum is shown in Fig. 
 MATED "OTH TYPES OF )N3!2 ARE DISCUSSED IN 3ECTION  4HE FORMER IS DISCUSSED IN h)NTERFEROMETRIC 3!2 FOR -OVING 4ARGET )NDICATION -4)  v AND THE LATTER IS DISCUSSED IN h)NTERFEROMETRIC 3!2 FOR 4ARGET (EIGHT -EASUREMENTv )NVERSE 3!2 3KOLNIK  PRESENTS A DISCUSSION OF )NVERSE 3!2 )3!2  (E STATES   h)N 3!2  THE TARGET IS ASSUMED STATIONARY AND THE RADAR IS IN MOTION )N )3!2  THE TARGET MOTION PROVIDES THE CHANGES IN RELATIVE VELOCITY THAT CAUSE DIFFERENT DOPPLER SHIFTS TO OCCUR ACROSS THE TARGETv PP n  3KOLNIK ALSO INCLUDES A DISCUSSION OF )3!2 IMAGES OF SHIPS OBTAINED BY THE 5 3 .AVAL 2ESEARCH ,ABORATORY .2,  -USMAN ET AL   !N AIRBORNE RADAR OBTAINS A SERIES OF IMAGES OF A SHIP THAT  IS EXPE 
 Clear-Air Radars. Another form of doppler radar that has become popular in the research community is the so-called wind profiler. Wind profilers usually . 
 The center frequency of a meander loop is the frequency at which the tape length is X/4. The time delay per meander loop is a function of the dimensions of the loop and the distance from the ground plane. To achieve a lin- ear delay-versus-frequency curve, several loops with staggered delay character- istics are used in series. 
 For example, Figure 11.5 shows that when the  pulse width and duty cycle for a given GaAs transistor is increased from 20 µs and 10%  to 3000 µs and 25%, respectively, there is a 70 °C increase in the overall junction tem - perature. Although the transistor may operate reliably at a desired output power level  for the shorter pulse width, it would suffer from a decrease in long-term reliability   if operated at the same power level for the longer pulse width. Thus, if required to Units Silicon GaAs InP SiC GaN Bandgap Energy eV  1.1  1.4  1.3 3.2 3.4 RF Power Density W/mm 0.6–0.8 0.8–1.8 0.2–0.4 2.0–4.0 3.0–10.0 Dielectric Constant — 11.8 12.8 12.5 9.7 9.0 Breakdown Field 106 V/cm  0.6  0.7  0.5 2.5 3.5 Thermal Conductivity W/m°C 130 46 68 370 170 Electron Mobility cm2 /Vsec 700 4700 5400 600 1600 Saturated Velocity 107 cm/sec  1.0  2.0  0.9 2.0 2.5TABLE 11.1  Key Semiconductor Characteristics of the Primary Semiconductors Used for Power  Generation in Solid-state Transmitters (The high saturated velocity, breakdown field, and thermal  conductivity of SiC and GaN make them attractive for high-power-amplifier applications.) ch11.indd   8 12/17/07   2:25:25 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The plate issimilarly manufactured. The plate islinked tothechannel byasystem of10pairs oftoggles and atierod, asshown inFig. 9.20. 
 Theregionfrom1000to4000kmmighttherefore requiretheradiation ofthreedifferent frequencies forfullcoverage. Ontheotherhand,there mightbetimeswhenionospheric. conditions allowthisregiontobecovered byonlyasingle frequency, whileatothertimesfiveorsixfrequencies mightberequired. 
 (2.3). The product kTo 4 x W/Hz. The purpose for  defining a standard temperature is to refer any measurements to a common basis of compari-  son. 
   PP n     & ' "ASS  ) - &UKS  ! ) +ALMYKOV  ) % /STRUVSKY  AND ! $ 2OSENBERG  h6ERY HIGH  FREQUENCY RADIO WAVE SCATTERING BY A DISTURBED SEA SURFACE v  )%%%  4RANS  VOL !0 
 38INTRODUCTION TORADAR SYSTEMS Complex targets.J2.JJTheradarcrosssectionofcomplex targetssuchasships,aircraft,cities, andterrainarecomplicated functions oftheviewing aspectandtheradarfrequency. Target crosssections maybecomputed withtheaidofdigitalcomputers, ortheymaybemeasured experimentally. Thetargetcrosssectioncanbemeasured withfull-scale targets,butitismore convenient tomakecross-section measurements onscalemodels attheproperscaled frequency.63 Acomplex targetmaybeconsidered ascomprising alargenumberofindependent objects thatscatterenergyinalldirections. 
 10, pp. 823–837, September 1991. 71. 
 REFERENCES  1. Skolnik, M. I.: Sea Echo, chap. 
 2AYLEIGH SEA CLUTTER v  )%%% 4RANS  VOL !%3 
 Therefore thedwelltimeinanydirection isdetermined notby theaverage number ofobservations madebyeachsequential detector, butbythatrange interval whichrequires thelargestnumberofobservations. Thiscanresultinrelatively long dwelltimes,anditispossible forthesavingsobtained withtheSequential Observer tobe negated. Th~required dwelltimemightbeevenlongerthanthatofthefixedsample-number Neyman-Pearson Observer. 
 VARYING 34# WITH AN EQUIVALENT 2#3 THRESHOLD INSIDE THE RANGE CORRELATION PROCESS 4HE 2#3 IS COMPUTED FOR EACH POSSIBLE UNFOLDED RANGE STARTING FROM THE SHORTEST RANGE  AND COMPARED TO THE 2#3 THRESHOLD $ETECTIONS THAT RANGE CORRELATE  BUT ARE BELOW THE 2#3 THRESHOLD  ARE PREVENTED FROM COR 
 1977..  Arlington, VA, IEEE Puhlicatio~r 77 CH 1255--9 EASCON; see atso' Microwave Systettt News, vol. 7,  pp. 
 Porcello: Optical Data Processing and Filtering  Systems, pp. 386-400.  8. 
 For small beamwidths, the doppler  frequency decreases linearly as the point-scatterer position changes relative to the radar and  goes to zero when the scatterer is at the center of the beam, after which the frequency increases.  The time-varying doppler frequency can be shown to be approximately1  (14.17)  where t0 is the time when the point scatterer is at the center of the beam, and R is the range lo  the scatterer at that time. The total width !l.fd of this doppler signal as the scatterer progresses  through the beam is 2v2Tj/lR, where Ta is the time during which the scatterer is within the  beam. 
 TARGET  DWELL TIME NECESSARY FOR ACCURATE MEASUREMENTS &INALLY  THE STORM ITSELF IS EVOLVING AND MOVING DURING THIS MEASUREMENT TIME  THUS COMPLICATING THE DATA REGISTRATION IN SPACE AND TIME 3OME OPERATIONAL AND MANY RESEARCH APPLICATIONS REQUIRE FASTER SCANNING THAN  CONVENTIONAL MECHANICALLY SCANNED RADARS CAN PROVIDE  4HESE APPLICATIONS INCLUDE  LONGER LEAD TIMES FOR TORNADO WARNINGS  THE STUDY OF FINER SCALE STORM FEATURES  INTERAC 
 WIDTH  SOLID 
 201-276. 8. Browne, J.: RF Devices Gain Higher Power Levels, Microwaves & RF, p. 
 Be- cause the frequency of the feedthrough is the same as the rear signal, for a system in which the front and rear signals are mixed directly (baseband conversion), feedthrough would occur at dc (zero frequency), with the approaching and receding spectra folded around it. As will be shown later, it is usually desirable to unfold the spectrum, to separate the approach and recede portions, so that feedthrough will oc- cur at some arbitrary offset frequency. Figure 19.3 illustrates the latter case. 
 The unused response, known as the image, is suppressed by the image- reject or single-sideband mixer shown in Fig. 3.3c. The RF hybrid produces a 90° phase differential between the LO inputs to the two mixers (which may be bal- anced mixers). 
 For example, if do = 6" and  0, = 20". the gain is reduced by 2.2 dB compared with a fan beam 6" wide. If 8, is made 40°,  the loss is 2.75 dB. 
 Fabrizio, D. A. Gray, and M. 
 POINT  THE CHALLENGE IS CONSIDERABLE  REQUIRING RADAR DESIGNERS TO DEVELOP COHERENT WAVEFORM  POLARIZATION 
   2!$!2 #2/33 3%#4)/.   £{°Ó THE CHART  4HE CHART SHOWS THAT IF THE ERROR DUE TO BACKGROUND SIGNALS IS TO BE  D" OR  LESS  THE BACKGROUND MUST BE AT LEAST  D" BELOW THE SIGNAL BEING MEASURED 4HREE DIFFERENT KINDS OF SUPPORT STRUCTURES HAVE BEEN DEMONSTRATED TO BE USEFUL IN  2#3 MEASUREMENTS 4HEY ARE THE LOW 
 CFAR or its equivalent is necessary when automatic tracking computers cannot handle large numbers of echo signals, but it should be avoided if possible. When an operator is used to make the threshold decision, CFAR is not a necessity as in limited- capacity automatic systems because the operator can usually recognize echoes due to clutter or to increased noise (such as jamming) and not confuse them with desired targets. Displays. 
 MEASURES EFFORT OFF GUARD BECAUSE THEY HAD NO IDEA THAT THE 5NITED +INGDOM AND THE 5NITED 3TATES COULD PRODUCE MICROWAVE RADAR 4HE SUCCESS OF THE MAGNETRON WAS A LARGE FACTOR IN THE EFFECTIVE APPLICATION OF MILITARY RADAR BY THE 5NITED 3TATES AND THE 5NITED +INGDOM DURING 7ORLD 7AR )) 4HE MAGNETRON IS AN EXAMPLE OF WHAT IS CALLED A  CROSSED 
 L. Frush, E. Loew, and C. 
 67. K. M. 
 In most other tubes the filnctions of  electron emission, RF interaction, and collection of electrons usually occur in the same region.  The design of such tubes must therefore be a compromise between good RF performance and  good heat dissipation. Unfortunately, these requirements cannot always be satisfied simulta-  neously. 
 BASED ENVELOPE DETECTOR  CONVERTING THE SIGNAL TO BASEBAND FOR SUBSEQUENT THRESHOLD PROCESSING 3ETTING THE THRESHOLD HAS BECOME INTIMATELY CONNECTED WITH THE SENSITIVITY TIME CONTROL 34#  OF THE RADAR 4HE FUN 
 "AND 3ATELLITES v  !)!! 3YMP     PP n  * + ( ,IN  ( &ANG  % )M  AND 5 / 1UIJANO  h#ONCEPT STUDY OF A M SPHERICAL REFLECTOR  SYSTEM FOR .%82!$ IN SPACE APPLICATION v PRESENTED AT TH !)!!!3-%!3#%!(3!3#  3TRUCTURES  3TRUCTURAL $YNAMICS  AND -ATERIALS #ONFERENCE  .EWPORT  2)  -AY n    2 &OWELL AND 7ANG  (  h0RECISION POINTING OF THE 4HURAYA SATELLITEv PRESENTED AT TH !!3  'UIDANCE AND #ONTROL #ONFERENCE  "RECKENRIDGE  #/  &EBRUARY n    2 # (ANSEN   -ICROWAVE 3CANNING !NTENNAS   .EW 9ORK !CADEMIC 0RESS  .EW 9ORK   ,OS  !LTOS  #! 0ENINSULA 0UBLISHING    * $ 7ALTON  *R ED   2ADOME %NGINEERING (ANDBOOK  .EW 9ORK -ARCEL $EKKER    - 3KOLNIK ED  2ADAR (ANDBOOK  ND %D  .EW 9ORK -C'RAW 
 LITE LAUNCHED IN  &IGURE    WHICH AS ITS NAME SUGGESTS  WAS DESIGNED FOR OCEANIC OBSERVATIONS 4HREE OF ITS SENSORS WERE 3"2SA SYNTHETIC APERTURE RADAR  AN ALTIMETER  AND A SCATTEROMETER !S THE READER WILL DISCOVER IN THIS CHAPTER  THESE THREE 3EASAT INSTRUMENTS ESTABLISHED THE INITIAL PARADIGM FOR VIRTUALLY ALL SUBSEQUENT RADARS OF THEIR RESPECTIVE CLASSES  #HAPTER . £n°Ó  2!$!2 (!.$"//+  4HIS CHAPTER DOES NOT COVER THE 4YPE ) SHORT 
 Thecrosssectioninoneplane(theverticalplaneinFig.7.16)isparabolic, whilethe crosssectionintheorthogonal planeiscircular. Thebeamanglemaybescanned bymoving thefeedalongacirclewhoseradiusisapproximately halftheradiusofthetoruscirck. Theradiusofthetorusismadelargeenoughsothattheportionofthecircularcrosssection illuminated bythefeedwillnotdifferappreciably fromthesurfaceofatrueparabola. 
 8, pp. 79-84, August, 1965.  9. 
 The threshold device is characterized by a value of receiver output voltage Vt (the threshold, equivalent to Marcum's3 bias level), which, if exceeded, results in the decision report that a signal is present. If the threshold voltage is not exceeded at a particular instant, the detector reports "no signal." There is always a definite probability that the threshold voltage will be ex- ceeded when in fact no signal is present. The statistics of thermal random-noise voltage are such that there is a usually small but nonzero probability that it can attain a value at least equal to the saturation level of the receiver. 
 18.34 Angle Noise (Glint)  ............................................  18.37  Range Noise (Range Glint)  ................................  18.43  Doppler Scintilla tion  ........................................... 
 LINE  CONSTANT 
 LEVEL LANGUAGES  SUCH AS # AND #    ! RELATED ADVANTAGE IS THAT PROGRAM 
 SYNCHRONOUS ORBIT  $IAGRAM COURTESY OF  *!8!  *APAN        #  &$!(' $#$  ) $!% " '% $  ) #$               " "      " (' !! '  % 
 805–820, April 1995. 157. S. 
 32. Schultz, F. V., R. 
 AP- 12, pp. 479-490, July, 1964.  I. 
 .. 583 1411Large Systems Where NoCommercial Power IsAvailable, 584 1412 Smaller Mobile Units 585 14.13 Ultraportable Units 5s5 14.14 Ship Radar Systems. 586 CHAP. 
 (a) Long-radius bend inwaveguide. (b) Miter elbOw. (c) Short-radius bend, electroformed fitting. 
 TAP &)2 FILTER WITH  SYMMETRIC COEFFICIENTS        &)'52%   )LLUSTRATION OF INTERPOLATION FILTERING    
 Canadian radar experts have done  much useful work with a modification of ASV designed  to locate shoals of fish swimming near the surface of  . THE TASK AHEAD 133  great Canadian lakes. It would be premature to antici-  pate too much success for underwater investigation by  radar, and when the main job is locating submerged  objects, then there may be a greater future for super-  sonic rather than electronic aids. 
 Substituting for doppler bandwidth in the underspread condition leads to  the constraint  T R N rR Lb TAzAz<1 (18.9) which shows how resolution and target illumination time may be traded against each  other while still respecting the fundamental ambiguity constraint. The following four  cases are important in practice. Strip Map. 
 PLEXITY AND EFFICIENCY )T HAS BEEN USED IN SEVERAL INSTRUMENTATION RADARS INCLUDING THE !.&01 
 However, it is more  sensitive lo variations in polarization and angle of incidence. The electrical characteristics of  the adhesive used for bonding the skins to the core must be taken into account in the design  since it can make the skin look (electrically) thicker than its physical length. The structure  must be pro\i,erly sealed against moisture absorption. 
 The eddy shape and brightness variations along eddy spirals in the simulated image appear to be consistent with the ENVISAT-1 ASAR image. Under the counterclockwise direction (the cyclonic eddy in the northern hemisphere rotates counterclockwise), the spirals show brightness variations from the outside to inside. The brightness variations along the longest spiral line A follow the order bright-dark-bright-dark, while spiral line B and C follows bright-dark. 
 Shore, and R. L. Haupt, “Methods for null control and their effects on the  radiation pattern,” IEEE Trans. 
 1262 - 1267, August, 1954.  14. Amitay, N., V. 
 I9Also,itismorc applicable tothemidrange ofgrazinganglesthantoverylowgrazinganglesortonearnormal incidence. Thereareothereffectsthatshouldprobably bepartofanycomplete theoryofsea c1utter.Suchfactorsinclude: theshadowing ofthewaveswhenthesurfaceisviewedatlow grazingangle;thespecular reflection fromplanefacetswhenviewedatnearnormalincidence; theeffectofbreaking waves,whitecaps, andfoam,especially whenthewindsaregreaterthan about15to20knots;andthepresence ofrefraction effects,suchasthatduetotheevaporation ductoverthesurfaceofthesea,whichenhance thepropagation ofradarwavesnearzero grazing anglesothatseaclutterisincreased atthelongerrangescompared tonormal propagation conditions. Backscatter fromseaice.Atlowgrazingangles,asmightoccurwithashipbo~~d radar,there islittlebackscattered energyfromsmooth, flatice.OnaPPIorsimilardisplaytheareasof icewillbedarkexceptperhaps attheedges.Ifareasofwaterarepresentalongwiththeice, '\theseaclutterseenonthedisplaywillberelatively brightincontrast totheice.Backscatter fromroughice,suchasfloesandpackice,canproduce aneffectontheradardisplaysimilar toseaclutter.However, thebackscatter fromroughicecanbedistinguished fromseaclutter sinceitspafTernonthedisplaywillremainstationary fromscantoscanbuttheseaclutter patternwillchangewithtime.33Measurements madeovericefieldsintheregionofThule, Greenland,41 indicated theradarbackscatter (0-°)tovarylinearlywithfrequency overarange ofgrazinganglesfromIto10°.Itwasalsofoundthat0-°wasproportional totheelevation angleovergrazinganglesfrom2°to10°,butwasinversely proportional tograzingangleover theregionfrom1°to2°.(Theincrease of0-°withdecreasing grazingangleissimilartothe behavior oflandclutterbutnotseaclutter.)Thescatterometer, aradarwhIchmeasures 0-°as afunctionofincidence angleintheregionnearverticalincidence, hasbeenusedasanicesensor andtodifferentiate between first-year andmulti-year ice.6s Radarcanalsodetectlargeicebergs, especially iftheyhavefacesthatarenearlyper­ pendicular totheradardirection ofpropagation.33Icebergs withslopingfacescanhavea smallechoeventhoughtheymaybelargeinsize.Growlers, whicharesmallicebergs large enoughtobeofdangertoships,arepoorradartargetsbecauseoftheirsmallsizeandshape. 
 If the frequency of the doppler-shifted echo signal were known beforehand, a  narrowband filter-one just wide enough to reduce the excess noise without eliminating a  significant amount of signal energy-might be used. If the waveform of the echo signal were  known, as well as its carrier frequency, the matched filter could be specified as outlined in  See. 10.2. 
 Relatively small changes (on the order of cm) in mean sea-surface  height may correspond to substantial differences in the corresponding geophysical  parameters. It follows that range measurement accuracy  and precision  are the driving  requirements for this class of radar. The accuracy of an altimeter’s height measurement  depends to first order on knowledge of the spacecraft’s height along its orbit and on  correction of the propagation delays suffered by the radar’s round-trip waveform. 
 An example of four simultaneous receive beams in a cluster  is shown in Figure 13.37. To search the same volume covered by this four beam cluster  with a single beam radar would take approximately four times as long since the trans - mit and receive beams would need to be sequentially scanned to each beam position.  Increasing the number of beams in the receive cluster, while also increasing the transmit  beam spoiling by an equivalent amount, reduces the search frame time. 
 THE PROPAGATION FACTOR, FP, IN THE RADAR EQUATION  26.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 Ducts not only give extended radar detection ranges for systems within the duct,  but they may also have a dramatic effect upon transmitter/receiver systems that tran - scend duct boundaries. For example, an air target that would normally be detected may  be missed if the radar is within or just above the duct and the target is just above the  duct. This area of reduced coverage is known as a radar hole  or shadow zone . 
 If a linear voltage ramp is applied to an ideal VCO, a linear-FM waveform is generated. A linear voltage ramp can be generated by applying a voltage step to an analog integrator. The integrator must be reset at the end of the generated pulse. 
 received from a given elevation angle, that correspond to one beamwidth. As stated in Sec. 8.4. 
 and the received signal is passed through a bank  of matched filters. each filter corresponding lo a ditTerent angular direction. This was men­ I ioned in Sec. 
 2004 ,42, 1344–1350. [ CrossRef ] ©2019 by the authors. Licensee MDPI, Basel, Switzerland. 
 TION IS THE TRANSMISSION OF A WAVE BETWEEN A TRANSMITTER AND A RECEIVER IN FREE SPACE &REE SPACE IS DEFINED AS A REGION WHOSE PROPERTIES ARE ISOTROPIC  HOMOGENEOUS  AND LOSS 
 Dolph-( 'lwhyslH.'\' arrays. Ro R ·1 This pattern produces the narrowest beamwidt h for a spcci lied  sidelohe le\'el. The beamwidth is measured by the distance between the first nulls that straddle  the main beam. 
 Nonstandard refractive conditions as discussed earlier  will cause the energy’s path to deviate from these assumptions, resulting in errors in  altitude calculations. Figure 26.3 shows the downward deviated path associated with  a surface ducting condition compared to the path under normal conditions. It can be  seen that actual altitude of the radar target is lower than calculated by the height- finding radar. 
 lnsrrumentation Papers no. 163, January, 1970.  36. 
 END THERMAL NOISE AT THE CANCELER OUTPUT 4HIS ALLOWS MAXIMUM SENSITIVITY WITHOUT AN EXCESSIVE FALSE 
 The difficulties are compounded when mixed paths  are involved; that is, when part of the propagation path lies over land, as happens  where islands are present in the coverage area. Focusing attention here on over-the-horizon detection, Figure 20.40 shows how the  surface wave decays with range, parametric in frequency for the case in which both  the radar antenna and the target are near the sea surface. These curves are for a smooth  surface and use a 4/3 earth radius to approximate atmospheric refraction effects. 
 1However, analternator furnishing voltage ofpoor waveform may show very marked changes inwaveform when itsload ischanged. Since astable d-cvoltage isthefinal require- ment inmost radar power supplies, itisnecessary tomaintain afixed relationship between the maximum voltage and the rms voltage, whose ratio iscalled the “crest” or*‘amplitude factor. ”The output d-c voltage forrectifier circuits employing condenser input will beafunction ofthe crest voltage. 
 R. Griffiths, “Video integration in radar and sonar systems,” J. Brit. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 FIGURE   16. 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 and phase are needed to force to zero the main antenna receiving pattern in N given  directions. The auxiliaries may be individual antennas or groups of receiving ele - ments of a phased-array antenna. 
 S1w1d(lrds (U.S.) J. Researc/1, vol. 64D. 
 C., and J. J. Bowman: Will Tactical Aircraft Use Bistatic Radar?, Microwave Syst. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft.  MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 main-beam clutter and ground moving target filter rejection notch. 
 The  particular example shown is tracking that might be used in FTT, GMTT, PVU, or A-G  Ranging, as shown previously in Figure 5.10, and later in Figures 5.32 and 5.38. It  consists of a frequency change; settling time; passive receiving to be sure the band isn’t  jammed; calibrate that doesn’t intentionally radiate but often there is some RF leakage  radiated; an automatic gain control (AGC) interval in which a number of pulses are  transmitted to set the receiver gain; and finally two intervals in which range, doppler, and  angle discriminants are formed. These CPIs often but not always have constant power,  frequency sequence, PRF sequence, pulsewidth, pulse compression, and bandwidth.7,8,9 5.3 A-A MODE DESCRIPTIONS & WAVEFORMS Air-to-Air Search, Acquisition and Track — Medium PRF. 
 53.Luneburg. R.K.:"Mathematical TheoryofOptics" (mimeographed lecturenotes),pp.212--213. BrownUniversity (/r<lduate School.Providence, R.I.,1944.Published byUniversity ofCalifornia Press,Berkeley. 
 The klystron was  followed by the traveling-wave tube, a close cousin with similar properties to the klystron  except for its wider bandwidth. The 1960s saw the availability of the crossed-field amplifier, a  tube related to the magnetron, There are several variations of crossed-field amplifiers, each  with its special properties; but they are all characterized by wide bandwidth, modest gain, and  a compactness more like that of the magnetron than the klystron or the traveling-wave tube.  Solid-state devices such as the transistor and the bulkcffect and avalanche diodes can  also be employed as radar transmitters. 
 Ulaby et al., “Millimeter-wave bistatic scattering from ground and vegetation targets,”  IEEE Trans. Geosc. & Rem. 
 * Increasing the radar fre - quency does not affect the signal-to-interference energy ratio within a radar resolution  cell when the antenna aperture and the radar data rate are held constant. The increased  frequency increases both the antenna gain and the number of radar resolution cells that  must be searched by equivalent amounts; the net effect is that the target return power  is increased by the same amount by which the target dwell time is decreased, thereby  holding the target-to-jamming energy ratio constant. Nevertheless, in practice, the  effect of main-beam noise jamming can be reduced with high radar frequency. 
 12.1, isusually provided bythesame square wave that turns onthecathode-ray tube. The timer generates asetofdiscrete range markers: sharp video pulses occurring atregular, precisely known intervals. Inaself-synchronous system, the markers must berecycled oneach transmitter pulse; this requires atransient oscillator. 
 The exact methods depend upon cir- cumstances and inparticular upon whether ornot the marker circuit provides the synchronization. Figure 13.37 gives atypical example in which itdoes so;Fig. 13.38, one inwhich itdoes not. 
 L. Jordan, J. Plaut, A. 
 )Acontrollable height marker can be derived, ifdesired, byapplying themodulated sawtooth toabiased-diode delay circuit, asexplained inSec. 13.12. V-beam Height Indicator.—In the V-beam height indicator (Fig. 
 TIONS FEED COVERS  WHICH OFTEN HAVE TO ENDURE PRESSURE  HIGH VOLTAGE  AND HEATIN G  COVERS ATTACHED TO THE REFLECTOR   WHICH ALTER THE PATTERN IN A FIXED MANNER AND  EXTERNAL RADOMES  WITHIN WHICH THE ANTENNA MOVES %XTERNAL RADOMES ARE THE MOST COMMON AND WILL  THEREFORE  BE EMPHASIZED 7ITHIN EACH CLASS  A VARIETY OF SKIN AND SKIN 
 The solution is in the form of a power series in the ratio of sea waveheight to radar  wavelength, and it predicts the first-order Bragg lines and second-order spectral filling  around the lines that were mentioned in the earlier section on HF sea clutter . On the other hand, the various integral formulations referenced above usually begin  with a very general expression for the fields scattered from the sea surface, which are  squared and ensemble-averaged over realizations of the sea surface to provide the  average power returned to the radar antenna, and then normalized to the illuminated  area as in Eq. 15.7. 
 40 Diurnal patterns of s 0 and liquid-water content  for snow at several frequencies. Note the extreme variation of the  Ka band as the sun starts to melt the surface. ( after W. 
 Long-term stability  mainly affects velocity or range accuracy or spurious signals (due to PRF harmonics)  but is relatively easy to make adequate. Short-term stability refers to variations within  the round-trip radar echo time or during the signal coherent integration time. The most  severe stability requirements relate to the generation of spurious modulation sidebands  on the main-beam clutter, which raise the system noise floor or can appear as targets at  the detectors. 
 superheterodyne Transmit/Receive/Device . spark gap *      Range accuracy wit hout calibration of range dial. **    Consisting of dipoles, 8 high and 4 wide. 
 The data for land clutter is usually reported in terms of oO, the cross section per unit area,  just as for sea clutter. However, it is sometimes given by a parameter y which equals cro/sin 4,  where 4 is the grazing angle. For ideal rough terrain, y is approximately independent of the  angle 4, except at low grazing angles and near perpendicular incidence. 
 Ambiguities in the  rneasuremerit ofdoppler frequency can occur in the case of the discontinuous measurement of  Fig. 4.2~. hut not when the measurement is made on the basis of a sing!e pulse. 
 Wilson: Radio Refraction in a Cool Exponential Atmosphere, MIT Lincoln Laboratory, Tech. Rept. 186, August 1958. 
 Dixon, R. C.: "Spread Spectrum Systems," Wiley Interscience, N.Y., 1976.  69. 
 5, no. 2, pp. 106–115, 1987. 
 Clutter to either side of the perpendicu-  lar will have a relative-velocity component and hence some doppler frequency shift; con-  sequently the clutter spectrum from the altitude return will be of finite width. The shape of the  MTIANnPliLSF DOPPLER RAnAR145 ispossihle tocomhinc tllctwotechniqucs forcompcnsating platform motionandscanning modulation. 5R Iftheantenna sidelobes ofanairborne MTIradararenotsufficiently low,theclutterthat entersthereceiver viathesidelobes cansetalimittotheimprovement factorequalt058 (4.40) whereG(O)istheonc-way powergainoftheantenna intheplaneofthegroundsurface.The lowerintegral istakenoutside themain-beam region.Thisassumes thesideJobes arewell distrihuted inazimuth. 
 RANGE RESOLUTION WOULD BE MAINTAINED AT ^ M OVER ALL BASELINE INCIDENT ANGLES !S A COROLLARY  THE WIDER BANDWIDTH AT  SHALLOWER INCIDENCE WOULD RESULT IN FINER RANGE RESOLUTION 4HE ANTENNA DESIGN WAS BASED ON HORIZONTAL RUNS OF  WAVEGUIDES  EACH CENTER 
 Radar Basics    . WHAT IS RADAR?  ................................ ................................ 
 Porcello: Optical Data Processing and Filtering System, IRE Trans., vol. IT-6, pp. 386-400, June 1960. 
 The unknown fields may be found by inverting the resulting ma- trix and multiplying the inverted matrix by a column matrix representing the in- cident field at each patch. The surface fields are then summed in integrals like Eqs. (11.9) and (11.10) to obtain the scattered field, which then may be inserted in . 
  AND SWEPT 
 The overall noise-  figure depends not only on the mixer stage, but also on the noise figure of the IF stage and the  mixer conversion loss. It may be determined from the expression for the noise figure of two  networks in cascade [Eq. (9.4)]. 
 METRIC 3!2  MOVING TARGETS  VIBRATING TARGETS  MEASUREMENT OF OBJECT HEIGHT  AND FOLI 
 POWER GYROTRONS OPERATE AT THE FUNDAMENTAL FREQUENCY OR ITS SECOND HARMONIC  "ECAUSE THE FREQUENCY OF A GYROTRON IS DETERMINED BY THE MAGNETIC FIELD AND  NOT BY THE SIZE OF THE FAST 
 tliatt. R. E., K. 
 19.2, the rear, or reference, doppler is a function of the radial velocity of the missile with respect to the illuminator. The/rowf, or target, doppler frequency, depends on the radial velocities of the illuminator, missile, and target. The resulting spectrum, when the front signal is coherently detected ILLUMINATOR FIG. 
 RECEIVE AND RECEIVE 
 and P. N. Pusey: A Model for Non-Rayleigh Sea Echo, IEEE Trans .• vol. 
 36. CCIR (International Radio Consultative Committee): World Distribution and Charac- teristics of Atmospheric Radio Noise, CCIR Rept. 322, International Telecommunica- tions Union, 1964. 
 Ê* 
 750-755, September.  1978.  90. 
 'Thus L, S ROB. Note that the maximum effective  length varies directly as the range. The other limit is determined by the far field of the synthetic  aperture; i.~., by the need to restrict the aperture size so that the phase front can be considered  as a plane wave. 
 -   ! ( 4AYLOR AND % / (ULBERT  h4HE PROPAGATION OF RADIO WAVES OVER THE EARTH v  0HYSICAL 2EVIEW   VOL   &EBRUARY    , ! 'EBHARD  h%VOLUTION OF NAVAL RADIO 
 5>- d d d d d  ( cl sin ¢  sin ¢  sin¢ ..  Figure 7.23 (a) Radiation pattern  £(</>) with sampled values A.jd radians  apart, where d = aperture dimen­ sion; (b) sampled values E,(n).Jd),  which specify the antenna pattern of  (a); (c) reconstructed paltern Ea(ef>)  using (sin i/J)N composing function  to approximate the desired radiation ·  pattern £( 4> ).  theory to construct the time waveform from the sampled values. 
 Similar results for a  two-dimensional model consisting or equal-cross-section scatterers uniformly spaced over a  circular area indicate that the probability that the apparent radar center lies outside this target  is 0.20.  Angle fluctuations in a tracking radar are reduced by increasing the time constant of the  AGC system (reducing the bandwidth).29·33·34 However, this reduction in angle fluctuation is  accompanied by a new component of noise caused by the amplitude fluctuations associated  with the echo signal; that is, narrowing the /\GC bandwidth generates additional noise in the  vicinity of zero frequency, and poorer tracking results. Amplitude noise modulates the  tracking-error signals and produces a new noise component, proportional to true tracking  errors. 
 Further, many phase shifters are of the digital type and require a driver and control signal for each bit. The prob- lems are eased somewhat in the system described above with two RF phase shifters in series, since many elements may use the same steering commands and the same drivers. In other systems it may be necessary to provide each element in the array with an independent phase command. 
 or ill~ir~rirr~~tiori, may be written as a complex quantity, including both the ampli-  tilde arid pllase. or  42) = I 44 l exp jy(zj (7.1 1)  / E(4)  _/ --  ' Y  Figure 7.2 Rectangular aperture and  coordinate system for illustrating the  relationship between the aperture dis-  tribution and the far-field electric-field-  intensity pattern.  RADAR ANTENNAS 229 severalantenna diameters fromtheaperture and,forthisreason,isusuallyoflittleimportance totheradarengineer. 
 27. Purves. c. 
 119.Johnson. C.M.:Ballistic-Missile DefenseRadars,IEEESpectrum, vol.7,pp.32-41,March,1970. 120.Weinsl<lck. 
 Other methods to avoid clutter saturation. The dynamic range ofa radar display, whether PPI  or A-scope, is far less than the range of echo-signal amplitudes that can be expected from  clutter. It is necessary, therefore, to keep the large clutter echoes from saturating the display  and preventing the detection of wanted targets. 
 SCALE BREAKING  OR OTHER STRONGLY NONLINEAR EVENTS  IS THE APPEARANCE OF hPARASITICv OR hBOUNDv CAPILLARIES ATTACHED TO THE EVENT AND MOVING WITH IT   4HEY TEND  TO BE SMALL 
 The resultant loss with the combining of a large number of devices  in some microwavedrcuits can sometimes negate the advantage achieved by combining. Thus  as a direct replacement for convention?} microwave tubes, solid-state devices have been  limited to low or moderate power applications.  A phased-array transmitting- antenna combines in space the power from each of many  transmitting sources. 
 The coherent detector does not destroy phase information as does the envelope detector,  nor does it destroy amplitude information as does the zero-crossings detector. Since it utilizes I 1 Balanced  mixer  Figure 10.5 Cotnparison of detection probabilities for signal known completely (coherent detector) and  for signal known except for phase (envelope detector). Low-pass  filter -  DETECTION OFRADAR SIGNALS INNOISE385 Input fa'epa Figure10.4Basicconfiguration ofacoherent detector. 
 SKOLNIK Second Edition Boston, Massachusetts Burr Ridge, Illinois Dubuque, Iowa Madison, Wisconsin New York, New York San Francisco, California St. Louis, Missouri . Library of Congress Cataloging-in-Publication Data Radar handbook / editor in chief, Merrill I. 
 LOBE CLUTTER LIMITED CASE SHOULD INCLUDE THE PROPER CLUTTER 2#3 FLUCTUATION MODELS AND #&!2 TECHNIQUES   -/Ê"Ê  , 
 •  Reliability of  deployment is a major  concern; mission  depends on it. Other •  Is transportability  a requirement?  Are there multiple  environments to  which the radar  antenna will be  exposed?•  Where on the  ship is the radar  antenna? Is it  covered with a  radome? Will it  be exposed to  water or wave  slap?•  V olume is a major  constraint, not  much room for  antenna apertures.•  Specialized  environments.     •  Launch drives  vibration and  acoustic loads. 
 B  Thus the character of ducting· is likely to differ over land and sea. Land masses change  temperature much more quickly than·does the sea. As a result, there is much more of a diurnal  variation of ducting over land than over sea, where it is likely to be more continuous and  widespread. 
 PLANE RANGE RESOLUTION IS COARSER THAN SLANT 
 aircraft28 is shown in Fig. 2.16. The aircraft is the B-26, a .World War II medium-range  two-engine bomber. 
 The data augmentation of all images allows the network to produce better feature representations. 2.3.2. Transfer Learning and Fine-Tuning Transfer learning is a learning technique that apply the known knowledge from one problem to other related problem [ 31]. 
 IN 
 The absolute accuracy ofthe circuit from the shaft ofthe doppler oscillator isabout. SEC.16.17] THERECEIVER 665 ~mph at10cm. Full circuit information can befound kareport byV.A. 
 282 9,8 The Kinematics ofMechanical Scanners 282 9.9 The Weight ofMechanical Scanners. 283 910 R-fTransmiesion Lines. 283 9,11 Data Transmission. 
 TION ACROSS THE CONTINUOUS APERTURE   %A A   COS  SIN   SIN SIN     PPPP 
 One such feature, perhaps the only one unique torain, isthat the raindrops are round; thus the intensity and phase ofthe reflection from asingle drop donot depend onthe direction inwhich theincident beam ispolarized. This cannot besaid ofmost radar targets, which, being complicated objects usually not rotationally symmetrical about the line ofsight, show very large variations, with polarization, ofthe total (complex) reflection coefficient. Anexperimental verification ofthe theory that this property ofsymmetry which ispeculiar toraindrops can beused todistinguish atarget signal inthemidst ofrain clutter hasbeen carried out. 
 The use ofsuch aninput circuit would require one more tube orthe equivalent thereof. Asanexperi- ment, oneofthestandard receivers was modified tousethis input circuit, thefirst seven tubes being inthe i-famplifier. The detector tube was replaced bya1>”34 germanium crystal, which allowed theunit tobecon- U FIG.1220.-Video amplifier for .\N/.lPS-lO. 
 The power amplifier is often preferred over the  power oscillator as the transmitter power source in high power, high performance  radar systems. In an amplifier, the signal to be transmitted is precisely generated at  a low power level and is then amplified to achieve the required power to be radi - ated from the antenna. Amplifiers have the advantage of being able to provide stable  waveforms, coded or frequency modulated pulse compression waveforms, frequency  agility, as well as combining and arraying. 
 TO 
 DIMENSIONAL ARRAY "ECAUSE OF THE LARGE NUMBER OF INDIVIDUAL MODULES IN A TYPICAL  SOLID 
 To  avoid this, the receiver gain can be reduced at short range and increased during the period  between pulses so that the received signal from a target of constant cross section remains  unchanged with range. The programmed control of the receiver gain to maintain a constant  echo signal strcnglh is called sensiti11it_v time comrol (STC). It is an effective method for  eliminating radar echoes due to unwanted birds and_ insects. 
 While in burst  mode, it is customary to use each burst as a single-look data take, setting the burst rep - etition frequency so that the desired number of looks is collected during the synthetic  aperture length of the azimuth beam pattern. The challenge is to calibrate the antenna  pattern such that the framelets from all bursts may be combined to assemble a continu - ous image along track. Mismatches appear as “scalloping”—systematic brightness  modulations at boundaries between each of the framelets. 
 The ScanSAR mode requires only half  that rate, 120 Mbit/s, which can be downlinked directly to ground stations. ALOS has  an onboard 96 Gbyte solid-state recorder to buffer data output from the radar, as well  as from the rest of the payload. PALSAR’s voluminous variety of modes is a curse as well as a blessing. 
 TOR IS SHOWN IN &IGURE   AGAIN AS A FUNCTION OF THE 2-3 RELATIVE SPECTRUM WIDTH  ASSUMING ZERO MEAN FOR THE SPECTRUM &)'52%  /PTIMUM IMPROVEMENT FACTOR FOR GAUSSIAN SPECTRUM MODEL . Ó°ÎÓ  2!$!2 (!.$"//+  &)'52%  /PTIMUM IMPROVEMENT FACTOR FOR POLYNOMIAL CLUTTER SPECTRUM MODEL &)'52%  /PTIMUM IMPROVEMENT FACTOR FOR "ILLINGSLEYS EXPONENTIAL SPECTRUM MODEL . 
 L. I. Parad and R. 
 OF 
 Electron. Syst. 2007 ,43, 1070–1075. 
 This also includes a compressive receiver which is ideal for CW signals. In this approach, the local oscillator is swept rapidly (chirped) to impress linear FM on the signal. A matched compressive delay-line filter then compresses the signal, producing a short pulse, the time of occurrence being indicative of RF frequency.25'26 Home-on-Jam.3'4'27 The HOJ mode is an essential part of a semiactive or ac- tive seeker. 
 High power and large antennas are readily practical. The stable transmitters and oscillators required for good MTI are easier to achieve than at higher frequencies, and there is relative freedom from the blind speeds that limit the effectiveness of MTI as the frequency is increased. Reflections from rain are not a problem. 
  
 5, pp. 248–257, October 2002. 175. 
 The RF power is extracted by placing a coupling  192INTRODUCTION TORADAR SYSTEMS Theklystron amplifier provides theradarsystemdesigner withhighpower,highgain, goodefficiency, andstability forMTIandpulse-compression applications. Ilisprobably the preferred tubeformosthigh-power radarapplications ifitshighoperating voltageandlarge sizecanbetolerated. Thetraveling-wave tubeissimilartotheklystron. 
 8-10, 1978. 38. Kalmykov, A. 
 Opt. Eng. 1995 ,34, 1599–1610. 
 1973.  RADAR ANTENNAS 273 tionofaphascdarrayantcnna capablc ofelcctronically scanning thebeamisaccomplished in thecomputer thatgenerates thesteering orders. Sometimes theterms{cI'dandcrossl('l'c{areusedtorefcrtotheanglesinastabilized system.14Thelcre{allyleistheanglebetween thehorizontal planeandthedeckplane, measured inthevertical planethrough thelineofsight.Thecross-level allgleistheangle. 
 24, McGraw-Hill Book Company, New York, 1950.  9. Oliver, B. 
 Radar has been helpful to both the ornithologist and entomologist  for better understanding the movements of birds and insects. It has also been dem - onstrated that radar can detect the gas seepage that is often found over underground  oil and gas deposits.10 1.10 CONCEPTUAL RADAR SYSTEM DESIGN There are various aspects to radar system design. But before a new radar that has not  existed previously can be manufactured, a conceptual design  has to be performed to  guide the actual development. 
 DEFENSE RADARS AND AIRCRAFT LANDING RADARS  WHICH SEARCH A LIMITED ANGULAR SECTOR AT A RAPID RATE EG   OR  TIMES A SECOND  III  4HE OTHER TYPE OF TRACK WHILE SCAN 473  WAS WHAT IS NOW CALLED AUTOMATIC DETECTION AND TRACKING !$4  4HE !$4  SYSTEM GENERATES TRACKS OF MORE THAN ONE TARGET BY USING A SERIES OF SCAN 
 13,  McGraw-Hill Book Company, New York, 1951.  17. Goldstein, H.: Frequency Dependence of the Properties of Sea Echo, Phys. 
 &- WAVEFORM WITH 4" AS LOW AS  4HE LEVEL OF SIDELOBE SUPPRESSION DEPENDS UPON THE TIME BANDWIDTH PRODUCT  THE WEIGHTING FUNC 
 PLER SPECTRUM IS OFTEN NOT PROCESSED SINCE TARGET DETECTABILITY IS SEVERELY DEGRADED IN THIS REGION  &URTHER  IN A HIGH 
 RADAR TRANSMITTERS 217  technology. Although there have been significant advances in microwave solid-state devices  and although they possess properties that differ from other microwave sources, the degree of  application or these devices to radar systems has been limited.  Microwave transistor.28 · 35·46 At L band the CW power that can be obtained from a single  microwave transistor might be several tens of watts. 
 4-7, 1986. 11. Guest editorial and invited papers in special issue on shortwave broadcasting, IEEE Trans. 
 TRIP DISTANCE FROM A RADAR TARGET TO THE CENTER OF THE SYNTHETIC ARRAY DIFFERS BY  K  FROM THE  ROUND 
 8 reflector analysis, 12.33 Geometric theory of diffraction, 14.24 to  14.25 Ge osat, 18.41 to 18.42 Ghosts, 2.88, 4.33, 14.35 Glint in bistatic radar, 23.20 to 23.21 in tracking radar, 9.30 to 9.35 Global Nearest Neighbor (GNN), 7.39 to 7.40 Graceful degradation, 13.4 Graded absorber, 14. 37 Grating lobes, 13.10 to 13.12 Gregorian antenna, 12.21, 12.25 Gregorian system, 14.33 to 14.34 Grid-controlled vacuum tubes, 10.21 to 10.23, 10.25 Grid locking, 7. 49 Ground echo available information from, 16.4 bistatic, 16.29 fading of, 16.12 to 16.19 at HF, 20.29 to 20.30 imaging radar interpretation, 16.55 to 16.56 at low grazing angle, 16.52 to 16.55 measurement techniques for, 16.19 to 16.29 in meteorological radar, 19.13 to 19.14 models for scattering coefficient, 16.29 to 16.34 near-g razing angle, 16.52 to 16.55 near-vertical, 16.25 number of independent samples, 16.24 parameters affecting, 16.4 to 16.7 polarimetry, 16.46 to 16.52 scattering coefficient data, 16.35 to 16.46 scattering coefficients from radar images, 16. 
 The transmitter signal can be sent via landline, via a communication link, or directly at the transmitter's RF if an ade- quate line of sight (LOS) exists between transmitter and receiver. If an adequate LOS is not available, it can be sent via a scatter path, where the scatterer has adequate LOS to both the transmitter and the receiver.49 In this case, the scatterer must lie in the common-coverage area, as defined by Eq. (25.12). 
 Its inherent Relative Motion mode  of operation makes it ideally suited for collision avoidance use—particularly as in this  mode it has no requirement to need own ship’s geographical position. However, radar  is basically confined to line-of-sight operation; its performance can be significantly Ship Dynamics Reporting Interval (seconds) At anchor or moored and not moving faster than 3 knots 180 With a speed of between 0–14 knots  10 With a speed of between 0–14 knots and changing course    3.33 With a speed of between 14–23 knots   6 With a speed of between 14–23 knots and changing course   2 With a speed of greater than 23 knots   2  With a speed of greater than 23 knots and changing course   2TABLE 22.5  AIS Position Reporting Intervals ( Courtesy of IMO ) ch22.indd   24 12/17/07   3:02:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Most fighter  radars are frequency agile since they will be operated in close proximity to similar or  identical systems. The frequency usually changes in a carefully controlled, completely  coherent manner during a CPI.8 This can be a weakness for certain kinds of jamming  since the phase and frequency of the next pulse is predictable. Sometimes to counter - act this weakness, the frequency sequence is pseudorandom from a predetermined set  with known autocorrelation properties, for example, Frank, Costas, Viterbi, P codes.16  A major difficulty with complex wideband frequency coding is that the phase shift - ers in a phase scanned array must be changed on an intra- or inter-pulse basis greatly  complicating beam steering control and absolute T/R channel phase delay. 
 For example, a block of numbers from 500 to 599 and 2500 to 2599 is reserved for Canadian use. The radars used in the air traffic control system of the FAA utilize the follow- ing nomenclature: ASR airport surveillance radar ARSR air route surveillance radar ASDE airport surface detection equipment TDWR terminal doppler weather radar The numeral following the letter designation indicates the particular radar model of that type. Weather radars in use by the U.S. 
 Very loosely, these three regions are ● Rayleigh region: typical body size < l ● Resonance region: l < typical body size < 3l ● Optics region: 3 l < typical body size The boundaries separating the three regimes are diffuse at best. The utility of our  RCS estimation and computation methods depends in large measure on where in this  size scheme we find our target. Although the complexity and size of most scattering objects preclude the applica - tion of exact methods of radar cross-section prediction, exact solutions for simple  bodies provide valuable checks for approximate methods. 
 Sensors 2017 ,17, 2683. [ CrossRef ][PubMed ] 7. Zheng, M.; Yan, H.; Zhang, L.; Yu, W.; Deng, Y.; Wang, R. 
 H. Staelin, and J. W. 
 8  IT WILL BE JOINED BY A COMPANION  4ANDEM 
 Spectral bandwidths of from  approximately 5 kHz to 100 kHz might be used, corresponding to effective pulse widttts of  200 /is and 10/is, respectively. (Actual pulse widths can be much longer, especially if pulse  compression is used.) The lower bandwidth limit of 5 kHz is set by the desire to be able to  operate in the quieter "holes" of the HF spectrirm. The wider the spectral width the less likely  that regions of the spectrum can be found without significant interference. 
 ALIASING FILTER  WHICH IS AN ANALOG LOWPASS OR BANDPASS FILTER THAT PLACES AN UPPER  LIMIT ON THE SIGNAL BANDWIDTH 4HE FILTER NEEDS TO PROVIDE ENOUGH STOPBAND REJECTION THAT ANY ALIASED COMPONENTS ARE INSIGNIFICANT /F COURSE  PRACTICAL FILTERS DO NOT HAVE &)'52%   A  .ON 
 7.23~.  The (sin $)/I) composing function is well suited for reconstructing the pattern. Its value at  a particular sample point is unity, but it is zero at all other sample points. 
 BACK ! 
  
 STATE DEVICES 7HILE HIGH 
 For horizontally or vertically polarized waves at low grazing angles,  the phase change upon reflection is approximately 180°. Whenever two or more wave  trains traveling over different paths intersect at a point in space, they are said to inter - fere (multipath interference). If two waves arrive at the same point in phase, they  constructively interfere, and the electric field strength is greater than either of the two  component waves taken alone. 
 Lhermitte152 was among the first to describe how two or more doppler  radars could be used, scanning together, to obtain the full three-dimensional air motion  ch19.indd   33 12/20/07   5:39:13 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 
  
     $ & !! "('  % #!  #(  # $  ##   &)'52%  #OMPLETE DOPPLER FILTER BANK DESIGN             
 ANGLE SEA CLUTTER  4HE GRAZING ANGLE GIVEN AS THE ABSCISSA  IS ACTUALLY A PLOT OF  INVERSE RANGE  SO THE LIFTING OF THE CROSS SECTION BY DUCTING OVER  AN ORDER 
 The drop across the cathode resistor ofVe,which isdue almost entirely tothe deflecting current, isfedback tothe cathode ofVsa. Because ofthe high gain in the feedback 106P, this voltage faithfully reproduces the form ofthe original sawtooth, thus assuring thedesired linear increase inthecurrent. Since any current through VCbetween sweeps would result inacircular rather than apoint origin forthesweep, this tube isbiased beyond cutoff. 
 If, for example, the RF  efficiency of a microwave tube were 40 to 50 percent, the transmitter efficiency might be 20 to  25 percent. (The actual number, of course, varies considerably with tube type and application.)  There are two basic radar-transmitter configurations. One is the self-excited oscillator,  exemplified by the magnetron. 
 The higher the frequency, the less the power available from an individual  solid-state device and the more difficult will be the combining problem because of the larger  number of devices required. At the lower microwave frequencies, the transistor is one oft he  better available solid-state sources. Since the transistor cannot operate efficiently with the low  duty-cycles characteristic of 'conventional radars, radars using transistors must operate with  long pulses or high pulse repetition frequency. 
 ii.. Effective aperture. Another usefulantenna parameter relatedtothegainistheeffective receiv­ ingaperture, oreffective area.Itmayberegarded asameasure oftheeffective areapresented. 
 AES-I I, pp. 647 649, July, 1975. (See also comment on p. 
 3. Clarke, J., D. E. 
 ( A  typical antenna pattern plotted as a function of one angular coordinate is shown in Fig. 7.1.)  Antenna beam shapes most commonly employed in radar are the pencil beam (Fig. 2.27£1) and  the fan beam (Fig. 
 88, pp. 485-495, 1962. 15. 
 I'lie standard @-/I tracker tloes not handle the maneuvering target. However, an adaptive  sc-/I tracker is one wllicll varies the two smootliitig parameters to achieve a variable bandwidth  so as to follow maneuvers. The value of a can be set by observing the measurement error  un - urn. 
 ,111glc resolrrtiotr detcrrniricd by tlie bearnwidtli; it car1 be less that1 lo which corresporids to  50 kni at a distatice of 3000 km.  I cry " he;itn splittirig" of orie part in 10 should be possible if tlie signal-to-noise  ratio is sufficierlt ; iotiosplieric effects rniglit lir~iit the angle measurement accuracy to some  fraction of a degree.  1)oppIer rcsol~ctiotr-resolution of targets wliose doppler frequencies differ by 0.1 Hz or less is  generally possible: at a radar frequeticy of 20 MHz, 0.1 Hz corresponds to a difference in  relative velocity of about 1.5 knots. 
 Duty  ratio is 10% with 15 dB required detection SNR. Averaged over all possible target posi - tions and closing dopplers, the losses for this mode are a surprisingly small 0.4 dB. The range-doppler blind zones plot is shown in Figure 5.19 corresponding to the  Figure 5.18 waveform. 
 ING BEHAVIOR IS DIFFERENT FROM THAT OBSERVED AT HIGHER FREQUENCIES 3CATTERING ALSO OCCURS FROM THE ENVIRONMENTCLUTTERSO MODELS OF THE SCATTERING COEFFICIENT PER UNIT AREA OF LAND AND OCEAN SURFACES  OR PER UNIT VOLUME OF THE TURBULENT IONOSPHERE  ARE USED TO PROVIDE EFFECTIVE 2#3 VALUES FOR %Q  WHEN THOSE NATURAL SCATTER 
 TATIONS OF SEVERAL TERMS )N THIS SECTION  THE MAJOR DEFINITIONS WILL BE REVIEWED AND ANNOTATED TO ATTEMPT TO CLARIFY SOME OF THESE POTENTIAL AMBIGUITIES &OR EACH TERM  THE )%%% DEFINITION  WHEN AVAILABLE  WILL BE QUOTED ALONG WITH A SUBSEQUENT DISCUSSION )MPROVEMENT &ACTOR  4HE )%%% DEFINITION OF )MPROVEMENT &ACTOR READS MOVING 
 Randall, “An inexpensive, mobile, rapid scan radar,” in 30th Int. Conf. on  Radar Meteorol. 
 73. D. Atlas, “Radar calibration: some simple approaches,” Bull. 
 FREE TAR 
 14. Brown, W. M.. 
 21. Croney, J.: Civil Marine Radar, chap. 31 of" Radar Handbook," M. 
 Skillman Westinghouse Electric Corporation 17.1 CHARACTERISTICSANDAPPLICATIONS Nomenclature. For the purpose of this chapter, the term pulse doppler (PD) will be used for radars to which the following apply: 1. They utilize coherent transmission and reception; that is, each transmitted pulse and the receiver local oscillator are synchronized to a free-running, highly stable oscillator. 
 Another reasonforpreferring thehigherfrequencies insomeapplications, inspiteofthelargerclutter, isthatgreaterrange-resolution andazimuth-resolution (shorter pulsewidthandnarrower beamwidths) areeasiertoobtainthanatlowerfrequencies. Thehigherresolution usually resultsingreatertarget-to-clutter ratio.Civilmarineradarsareavailable atbothSband (10emwavelength) andXband(3em).Although bothbandshavedistinctive advantages for shipapplication, whenonlyasi~gleradarisemployed itisusuallyatXbandforthereasons givenabove. 2\Thusthefactthatseaclutterislessatthelowerfrequencies isbutoneofseveral factorstobeconsidered intheselection oftheoptimum frequency foraparticular radar application. 
 V . Trunk, “Range resolution of targets using automatic detectors,” IEEE Trans ., vol. AES-14,  pp. 
 TION ANGLE MEASUREMENTS ON TARGETS 2ANGE MEASUREMENTS ARE OBTAINED USING RANGE GAT 
 4.6.  55. Severin, H.: Nonretkcting Absorbers for Microwave Radiation, I RE Tra11s., vol. 
 0ACIFIC v  $EFENCE  4ODAY   HTTPWWWAUSAIRPOWERNET  $4 
 Bogle, and D. D. Crombie: Sea Backscatter at HF: Interpretation and Utilization of the Echo, Proc. 
 80. A. Farina, A. 
 G.: A Broad-band Twist Reflector, IEEE Trans., vol. AP-19, pp. 552-554, July, 1971. 
 96 INTRODUCTION TO RADAR SYSTEMS  Since the two RF frequencies/ 1 andfi are approximately the same (that is.Ji = /1 + A/, where  flf 4:fd the doppler frequency shifts /di and fd2 are approximately equal to one another.  Therefore we may write /.t1 = I.ti = h.  The receiver separates the two components of the echo signal and heterodynes each  received signal component with the corresponding transmitted waveform and extracts the two  doppler-frequency components given below:  The phase difference between these two components is  Hence fl</> = 41t(/2 -/1 )Ro = 4n 4{R0  C C  C fl</>  Ro= 4n flf  which is the same as that of Eq. 
 D. L. Malone, “FLYCATCHER,” Nat. 
 Quadrature errors in synchronous (i.e., I, Q) detectors64–66 ch24.indd   16 12/19/07   6:00:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 This is accomplished by use of microwave hybrids to subtract outputs of pairs of horns, providing a sensitive device that gives signal output when there is an un- balance caused by the target being off axis. The RF circuitry for a conventional four-horn square (Fig. 18.8) subtracts the output of the left pair from the output of the right pair to sense any unbalance in the azimuth direction. 
 — sm,ArA”(1) shows that allfactors except Pand tl~,n areeither invariable orbeyond our control once theradar has been designed. Aquantity closely related toSmin isusually measured rather than Sti~ itself. This maybe thepower oftheweakest test signal that can be detected, orofatest signal that produces some other easily reproducible effect. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 22.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 The tracking problem is complicated by the fact that basic radar measurements  are made relative to the ship’s motion, but the display may be set to relative or true  motion. 
 Therefore(α,γ) α=360−φ γ=90−θCONSTANT   ELEVATION xyz θ φγZENITH HORIZON  P αrTarget  Constant El cut Constant Az cut  Radar. 21Radar Display Types RANGE (TIME)RECEIVED POWERTARGET  RETURN AZIMUTH RANGE 0 -180 180TARGET  BLIP"A" DISPLAY "B" DISPLAY "C" DISPLAYPLAN POSITION  INDICATOR (PPI) AZIMUTHELEVATION 0 -180 180TARGET  BLIP 090RANGE  UNITS RADAR AT  CENTERAZIMUTH TARGET  BLIP. 22Pulsed Waveform • In practice multiple pulses are transmitted to: 1. 
 38 INTRODUCTION TO RADAR SYSTEMS  Complex targets.32·33 The radar cross section of complex targets such as ships, aircraft, cities,  and terrain are complicated functions of the viewing aspect and the radar frequency. Target  cross sections may be computed with the aid of digital computers, or they may be measured  experimentally. The target cross section can be measured with full-scale targets, but it is more  convenient to make cross-section measurements on scale models at the proper scaled  frequency. 
 OUTPUT LEVELS !S SHOWN IN &IGURE   THE SMALLEST PHYSICAL CONSTRUCTION DIMENSION  OF THE GATE ELECTRODE IS CALLED THE  GATE LENGTH THE LONGER OF THE DIMENSIONS IS CALLED  THE GATE WIDTH 4HE CURRENT CARRYING CAPABILITY  AND HENCE THE POWER CAPABILITY  OF THE  &%4 IS INCREASED AS THE GATE WIDTH IS INCREASED 4HERE IS A LIMIT AS TO HOW LONG THE GATE WIDTH CAN BE INCREASED BEFORE PHASE DIFFERENTIAL AND SIGNAL ATTENUATION ALONG THE LONGER DIMENSION OF THE GATE WIDTH BEGIN TO HAVE A DELETERIOUS IMPACT ON AMPLIFIER PERFOR 
 All the known Barker codes are listed in Table 10.4 and are the codes which have a minimum peak sidelobe of 1. These codes would be ideal for pulse compression radars if longer lengths were avail- able. However, no Barker codes greater than 13 have been found to exist.22"24 A pulse compression radar using these Barker codes would be limited to a maxi- mum compression ratio of 13. 
 19-24, December, 1976.  93. Howard, D. 
 In practice, stagger tuning enables the bandwidth  of the multicavity klystron amplifier to be increased from a synchronously tuned bandwidth of  ! to l percent to values of more than 5 percent. Multicavity klystrons can be designed with  bandwidths as large as 10 to 12 percent or greater.7•10•41•50  Tuning. Although conventional klystrons are of narrow bandwidth, they may be tuned over a  wide frequency range. 
 The loop gain of the AGC filter measured at the conical-scan frequency should be low so that  the error signal will not be affected by AGC action. (H the AGC responds to the conical-scan  frequency, the error signal might be lost.) The phase shirt or this filter must be small ir its phase  characteristic is not to influence the error signal. A phase change of the error signal is eq uiva­ lent to a rotation of the reference axes and introduces cross coupling, or" cross talk," between  the elevation and azimuth angle-tracking loops. 
 CORRELATES THE RECEIVED WAVEFORM WITH A SUITABLY TIME 
  D"C  
 16. Sensors 2019 ,19, 1701   Figure 8. Scale difference of two methods. 
 The computer analysis described measures the colored modulation spectrum of the stalo, modifies it in conformance with the range-dependent effect and re- ceiver filters of the radar, and integrates the output residue power. It is a valid procedure for determining stalo stability that requires no assump- tions, but the resulting value must be considered merely a figure of merit to com- pare different stales for a given application. The same stalo would have a differ- ent stability value in another application with different receiver filters. 
 . 
 Thus the sea or  a metallic object may appear very cold if it is oriented to reflect radiation from the sky to the  antenna. The choice of polarization also influences the ainount of sea or land absorption.  Vertical polarization is absorbed more than horizontal. 
 LOBE AMPLITUDE AS FUNCTIONS OF BANDWIDTH PHASED  SUBARRAYS WITH TIME DELAY  SCANNED n   4HE VALUE OF THE GRATING LOBE WILL BE MODIFIED BY THE  ELEMENT PATTERN . 
 60, pp. 735-736, June,  1972.  88. 
 Some skywave radar designs call for up to six bands.  A related issue is the occurrence of mutual coupling between antenna elements in the  transmit array.65 Energy coupled back into an amplifier from its neighbors can reach  levels that result in intermodulation distortion, as well as causing load resonances that  stress the amplifier chain. Antennas. 
 1036. Like the hard-tube pulser, theline-type pulser isbest analyzed byseparate consideration of Isolation orchargingPulseformingnetwork---—— ----- - impedance I Pulsetransmission cable Damping ,----, d== Despiking ‘ circuit ●m!!?i,/i““--1 I IILoad m, I:’a’ II II1, * l__–_l + FIa. 1036.-Basic circuit for aline-type pulser. 
 DOMAIN DIGITAL PULSE COMPRESSION PROCESSING -ULTI 
 /,"  Ê "1 / 
   
 If a high-PRF waveform is used, the clear-range region disappears because the sidelobe clutter folds in range into the unambiguous range interval (assuming the target doppler is such that it still competes with the sidelobe clutter). However, in64-POI NT FFT MAIN-BEAMCLUTTER SIDELOBECLUTTER ALTITUDE LINE(CLUTTER + NOISE)/NOISE (dB) . those doppler regions free of sidelobe clutter, as shown in Figs. 
 M. Chow, “Range and doppler resolution of a frequency-scanned filter,” Proc. IEE , vol. 
 I. Skolnik: Over-the-Horizon Radar in the HF Band, Proc. IEEE, vol. 
 While Fig. 25.8 shows the clear dependency of bistatic RCS on both aspect and bistatic angle, it also serves to caution attempts to use oversimplified bistatic RCS models, especially in the bistatic region. 25.8 CLUTTER The bistatic radar cross section of clutter uc is a measure, as is the monostatic radar clutter cross section, of the energy scattered from a clutter cell arzaAc in the direction of the receiver. 
 NIQUE DOES NOT APPLY TO RADARS OPERATING IN HIGH 
 19,   pp. 413–430, 2002. 132. 
 This confusion of concepts might be avoided by  visualizing the radar as extracting the “Bragg line” from the spectral compositions of  those surface features that contain a wave of length l /2cosy  in their Fourier repre - sentation , independent of the existence of such a wave as a real object. Nevertheless, this direct linear relation between radar cross section and the ocean - ographers’ descriptor of the sea surface has had a powerful influence on thinking about  the physical origins of sea clutter. It is appealing in its simplicity, and it suggests a  direct way both to predict radar clutter from measurements or forecasts of the sea spec - trum and, inversely, to use radar backscatter measurements to provide remote sensing  of the sea surface for oceanographic and meteorological applications—provided, of  course, that it correctly describes this relationship. 
   #)6), -!2).% 2!$!2   ÓÓ°£Ç )N PREVIOUS YEARS  SHIPS WERE REQUIRED TO HAVE A RADIO OFFICER  WHO COULD CARRY OUT  RADAR REPAIRS AT SEA 4HIS IS NO LONGER THE CASE 2ELIABILITY IS A PRIME CONCERN  AS A NON 
 Experimentation with millimeter wavelength radiation and  microwave radiation both date back to the end of the nineteenth century. The first microwave  experiments were those of Hertz in 1886. Experiments at 6-mm wavelength occurred in 1895.80  In the early 1920s, millimeter-wave research was reported in the United States, Germany, and  Russia, with wavelengths as short as 0.22 mm.81 Although many important applications of the  microwave region have been developed, there has been almost no comparable activity in the  millimeter-wave region. 
 % g.gt~. ~$ w+ mIG+ %.1Q.s ~I o0 1 2 3 4Elevationangleindegrees ~lG.6.21.—Ratio ofsignals inlower and upper beams. ratio between thesignal strength inthelower beam and that intheupper asafunction ofelevation angle. 
 PURPOSE PRO 
 N. Radcliffe: Pulse Compression and Signal Processing, International Confer­ ence on Radar-Present and Future, Oct. 23-25, 1973, pp. 
 J. Hydraul. Eng. 
 DIMENSIONAL  PHASED 
 The rainfall rate can be empirically related to the reflectivity factor12 by an expression of the form Z = aRb (23.43) where a and b are constants and R is the rainfall rate, usually in millimeters per hour. Battan10 devotes three full pages of his book to the listing of dozens of Z-R relation- ships derived by investigators at various locations throughout the world, for various weather conditions and in all seasons of the year. The fact that no universal expres- sion can be applied to all weather situations is not surprising when one notes that rainfall drop-size distributions are highly variable. 
 The required digital phase increment is obtained by operating on a minor  hysteresis loop. :is ill Fig. 8.12. 
 Kat7, arid L. M. Spetner: Phenomenological Vector Model of Microwave Reflection  frorn tile Ocean, IRE Trans., vol. 
 A.: 3 cm and 10 cm Wavelength Radiation Backscatter from Rain, Proc. Fifth Weather Radar Conf., pp. 281-285, American Meteorological Society, Boston, 1955. 
 J. 1997 ,10, 171–186. 25. 
 Zappa, “QR versus IQR  algorithms for adaptive signal processing: performance evaluation for radar applications,”  IEE Proc ., vol. 143, pt. F, no. 
 ABSORBING MATERIAL TO SUPPRESS THE ECHOES FROM THE LEADING AND TRAILING EDGES 4HE OBVIOUS ADVANTAGE OF THE METAL PYLON IS ITS SUPERIOR WEIGHT 
 TIME DOMAIN PROCESSING MAY BE PERFORMED VIRTUALLY IN REAL TIME A SECOND OR TWO FOR PROCESSING AND DISPLAY ON A VIDEO SCREEN   BUT THE CONVERSION  &)'52%   2ADAR IMAGE OF A SMALL DRONE AIRCRAFT 0LANFORM  OUTLINE HAS BEEN ADDED FOR CLARITY  #OURTESY $ , -ENSA  53  .AVY 0ACIFIC -ISSILE 4EST #ENTER   . 
 OFFS  VACUUM ELECTRONICS VS SOLID 
 Because of the phase relationships between the lobes of the difference  pattern and the sum pattern, the resu1t is an apparent forward displacement of the pattern on  the first transmission, and a displacement to the rear on the second transmission. When th~  gains of the sum and difference channels are properly adjusted, and when the distance between  the phase centers of the two antenna beams is 2Tpvx the combined sum and difference p~tterns  on successive pulses illuminate the same region and the antenna appears stationary. 511 (The  factor 2 appea·rs in the distance between phase centers. 
 NOISE RATIOS  THE ACCURACY RMS ERROR  OF THE BEAM 
 Separate antennas are needed since it is . TRACKING RADAR 167  difficult to illuminate a single rellector with more than one feed and produce independent  antenna patterns which illuminate the same volume in space.  Although tracking radars based upon the phase-comparison monopulse principle have  been built and operated, this technique has not been as widely used as some of the other  angle-tracking methods. 
 REFERENCED PARALLEL INDEX 0)  LINES TO BE HIGHLY USEFUL ! 0) IS A STRAIGHT LINE ON THE RADAR DISPLAY THAT IS USER 
 Since the two orbits are separated,  each area is observed at a slightly different incident angle. This implies that the effec - tive wavelength projected onto the ground plane is slightly different for the two cases.  Interference is supported only if the range bandwidth of the radar signal is sufficient to  span the projected wavelengths, which becomes more demanding as the orbit separa - tion increases.51 Fortunately, the range pulse has sufficient bandwidth (usually more  than 15 MHz) so that mutually coherent range bandwidths can be chosen from the data  at the time of processing. 
 itis necessary todigressandreviewbrieflysometopicsinprobability theoryinordertodescribe thesignal-to-noise ratioinstatistical terms.. 20 INTRODUCTION TO RADAR SYSTEMS  2.4 PROBABILITY-DENSITY FUNCTIONS  The basic concepts of probability theory needed in solving noise problems may be found in  any of several In this section we shall briefly review probability and the  probability-density function and cite some examples.  Noise is a random phenomenon. 
 ING THERMAL NOISE  !N .2! IS AN AREA WITH ESSENTIALLY ZERO RETURNFOR EXAMPLE  A SHADOW AREA  A VERY SMOOTH AREA SUCH AS A CALM LAKE  OR A SPECIALLY CONSTRUCTED LARGE SHEET OF ALUMINUM !NOTHER  SIMILAR 3!2 IMAGE QUALITY METRIC )1-  IS THE  CONTRAST RATIO #2    DEFINED AS THE RATIO OF THE  AVERAGE INTENSITY OF A TYPICAL BRIG HT REGION IN A 3!2 IMAGE  TO THE INTENSITY OF AN .2! )F THERMAL NOISE IS NEGLIGIBLE  THEN #2   -.2 #OMPARISON OF 3!2 )MAGERY AND /PTICAL )MAGERY  4HE HUMAN EYE IS  OF  COURSE  A SYSTEM FOR PRODUCING IMAGES USING VISIBLE LIGHT 4HE LIGHT HITS THE LENS AND IS FOCUSED UPON THE RETINA  AND THE RESULTING IMAGE IS TRANSMITTED TO THE BRAIN /VER MANY MILLENNIA  HUMANS HAVE BECOME FULLY ACCUSTOMED TO SEEING AND PROCESSING THIS VIS 
 Great care must be taken, therefore, tocool thegrid byfins, heavy rods, and other means, for itcan emit afew milliamperes even atasub-visible temperature. Afew milliamperes may sound small incomparison with several amperes pulse current, but afew milliamperes flowing allthe time can cause serious heating ofthe anode and screen, which areatrelatively high potentials. Usually the result isarunaway condition inwhich grid control islost. 
 1968.  12. Moore. 
 SPECIFIC AND PROGRAMMABLE PROCESSORS $EDICATED PROCESSORS  SUCH AS &0'!S OR !3)#S  ARE TYPI 
 22.29  Global Air Traffic Su rveillance  ............................  22.30  Military SBR Systems  ........................................  22.31  23. 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .456x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 a track from three (out of five) to five (out of eight) increases the density of false  alarms that can be tolerated by more than an order of magnitude. Forward- and  backward-tracking algorithms produce similar numbers of false tracks. 
 The performance of the log-  arithmic receiver in non-Rayleigh clutter is almost as good as the trl-out-of-,] detector and is  probably easier to implcment.14.28  A comparison of the performance of the various receivers for a specific case is shown in  Fig. 13.7.  Log-FTC and log-log receivers. 
 IEEE, vol. 73, pp. 198-204, February 1985. 
 ¤ ¦¥³ µ´ 
 RANGE INSTRUMENTATION 
 Some of the indicated ITU bands  are restricted in their usage; for example, the band between 4.2 and 4.4 GHz is reserved  Band Designation Nominal Frequency RangeSpecific Frequency Ranges for Radar Based  on ITU Frequency Assignments   for Region 2 HF 3 MHz–30 MHz VHF 30–300 MHz 138–144 MHz 216–225 MHz UHF 300–1000 MHz 420–450 MHz 890–942 MHz L 1.0–2.0 GHz 1215–1400 MHz S 2.0–4.0 GHz 2.3–2.5 GHz 2.7–3.7 GHz C 4.0–8.0 GHz 4.2–4.4 GHz 5.25–5.925 GHz X 8.0–12.0 GHz 8.5–10.68 GHz Ku 12.0–18.0 GHz 13.4–14.0 GHz 15.7–17.7 GHz K 18.0–27.0 GHz 24.05–24.25 GHz 24.65–24.75 GHz Ka 27.0–40.0 GHz 33.4–36.0 GHz V 40.0–75 GHz 59.0–64.0 GHz W 75.0–110 GHz 76.0–81 GHz 92.0–100 GHzTABLE 1.1  IEEE Standard Letter Designations for Radar-Frequency Bands5 ch01.indd   13 11/30/07   4:34:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 
 butin oneimplementation ithasheensaid34tohaveapotential elevation accuracy ofabout0.20 • Mullipath reflections canalsodegrade theaccuracy ofthismethod. butsincethephase-in­ spacetechnique employs multiple beamstoshapeitselevation pattern. itmighthepossible to control theradiation soastoilluminate thesurfacewithlessenergythantheconventional fan-beam antenna. 
 4IME !DAPTIVE 0ROCESSING   RD %D  ,ONDON  5+ )%4 2ADAR   3ONAR AND .AVIGATION 3ERIES     2 +LEMM ED    !PPLICATIONS OF 3PACE 
 AXIS PEDESTAL 4YPICAL INSTANTANEOUS  ELECTRONIC ANGLE COVERAGE IS  o TO AN ALMOST  o CONE FIELD 
 105] MAGNETRON CHARACTERISTICS 349 Frequency Pulling bytheR-jLoad. -Magnetrons are self-excited oscillators whose frequency depends onoutput loading. Inthe process ofscanning bythe radar antenna, itisinevitable that variations inthe magnetron loading will occur asaresult ofchanging reflections from rotary joints, antenna housings, and large near-by reflecting objects. 
 NOISE RATIO SEE 3ECTION   4HUS  THE THEORETICAL ACCURACY  FOR TERRAIN ALTITUDE MEASUREMENT IS 6ERTICAL ANTENNA SEPARATION NO BANKING    DL PH2 N,  3.2    &)'52%   )N3!2 
 Signals which  make single reflections (or any odd number) will be rejected by the circularly polarized antenna  that transmitted it, but those which make two reflectio~is (or any even number) will be  accepted. In addition to the mechanism of the double bounce, depolarization (or generation  of the orthogonal component) can occur when the objects causing the scattering are not sym-  metrical. With most targets of interest, the scatterers are asymmetrical and backscatter energy  appears in both orthogonal polarization components. 
 R., and C. W. Young, Jr.: The Evolution of Ferrite Control Components. 
 SEC. 14.6] SPEED REGULATORS 575 FIG.14.18.–I!Ehl‘tt$$ F?---Carbon.pileIRegulating MOioShuntvoltagefieldregulator ,field ~i: i1---- J Alternator -‘~field I \ I -=_J = Stabilizing transformer-Alternator = armature P ~“ -Schematic wiring diagram ofPU-7 aircraft motor-alternator, 2500 400Cps.Va. 115 Volta. 
 ASV Mk. IIIA parameters. Transmitter –receiver (TR. 
 B.: An Advanced Computer Calculation of Ground Clutter in an Airborne Pulse Doppler Radar, NAECON '77 Rec., pp. 921-928. Reprinted in Barton, D. 
 (12.1)442INTRODUCTION TORADAR SYSTEMS 12.2PROPAGATION OVERAPLANE EARTH Although therearebutfewsituations whereaccurate predictions ofradarpropagation effects canbemadebyassuming aflatratherthanroundearth,itisnevertheless instructive to examine thisspecialcase.Theassumption ofaflatearthsimplifies theanalysis andillustrates thetypeofchanges introduced inradarcoverage byareflecting groundorseasurface. Consider theearthtobeaplane,flat,reflecting surfacewiththeradarantenna locatedat heightha•Thetargetisataheighth,andatadistance Rfromtheradar.Figure12.1illustrates thatenergyradiated fromtheradarantenna arrivesatthetargetviatwoseparate paths.Oneis thedirectpathfromradartothetarget;theotheristhepathreflected fromthesurfaceofthe earth.Theechosignalreradiated bythetargetarrivesbackattheradarviathesametwo paths.Thusthereceived echoiscomposed oftwocomponents traveling separate paths.The magnitude oftheresultant echosignalwilldepe~dupontheamplitudes andrylativephase difference between thedirectandthesurface-reflected signals. Modification ofthefield strength (voltspermeter)atthetargetcausedbythepresence ofthesurfacemaybeexpressed bytheratio fieldstrength attargetinpresence ofsurface rt=fieldstrength attargetifinfreespace-. 
 The output of the phase detector is then chopped at the radar's pulse rep- etition frequency and duty factor. The folding, thus produced, accurately repro- duces the radar's demands on its source. The required I//2 frequency response of the servo is a convenient and stable choice. 
 124. Walton. J. 
 [ CrossRef ][PubMed ] 15. Teng, F.; Hong, W.; Lin, Y. Aspect Entropy Extraction Using Circular SAR Data and Scattering Anisotropy Analysis. 
 New York, 1948.  2. Torrieri, D. 
 The arms are rotated to  prodilce a cotitiriuous arid utiiforni variation of phase across the elements of the array. Wlien  the phase at one end of tlie concentric line is increasing, the phase at the other end is  decreasing. Hence one line car1 supply the necessary phase variation to two elements, one on  either side of array center. 
 10.2] THERESONANT SYSTEM 325 magnetron with radial cathode supports. Another type ofmagnetron construction, favored forthehigher-frequency magnetrons where magnet weight isofimportance, isshown inFig. 10.4b. 
 The strategy was also used in modi ﬁed form in much more con ﬁned areas, but was superseded by the advent of centimetric ASV. 2.2.8 The Vixen attenuator One possible countermeasure to the Metox warning receiver was to reduce the transmitted power as the radar approached the U-boat, so that it would appear not to be getting closer. Equipment for achieving this was designed in a squadron and tested by CCDU in June 1943 [ 15]. 
 E.: Multipath Phase Errors in CW-FM Tracking Systems, IRE Trans .• vol. AP-3,  pp. 185-192. 
 .   -4) 2!$!2  Ó°n£ UNSATISFACTORY BECAUSE THE WIND FIELD RARELY IS HOMOGENEOUS OVER A LARGE GEOGRAPHICAL  AREA AND BECAUSE THE WIND VELOCITY USUALLY IS A FUNCTION OF ALTITUDE DUE TO WIND SHEAR IMPORTANT FOR RAIN CLUTTER AND CHAFF  !GAINST A SINGLE CLUTTER SOURCE  AN IMPLEMENTA 
 C. J. Sletten, “The theory of reflector antennas,” Air Force Cambridge Res. 
 A comparison of these five models for a false-alarm number "I= 108 is shown in Fig. 2.22  for 11 = 10 hits integrated. When the detection probability is large, all four cases in which the  target cross section is not constant require greater signal-to-noise ratio than the constant cross  section of case 5. 
 DOPPLER FILTER IS THE MIRROR IMAGE OF THIS ONE &IGURE D SHOWS THE COMPOSITE RESPONSE OF THE FILTER BANK .OTE THAT THE FILTER  PEAKS ARE FAIRLY EVENLY DISTRIBUTED 4HE DIP BETWEEN THE FIRST ZERO 
 The  matched filter impulse response with k1 = 1 and t1 = 0 is   h t u tmf( ) ( )*= −  (8.53) The matched filter input signal is assumed to have zero time delay and a doppler  shift fd:  s t u tej f td ( ) ( )=2π (8.54) †  The terminology for this function is not standardized in the literature. Woodward69 uses the term correlation func - tion. The term time-frequency autocorrelation function is used by Spafford.80 The signs associated with t  and fd  within the integrand also differ in the literature. 
 Hanado, N. Takahashi, T. Iquchi, and  K. 
 1.17  X Band (8.0 to 12.5 GHz)  ...................................  1.17 K u, K, and K a Bands (12.5 to 40.0 GHz)  .............  1.17  Millimeter Wavelengths ( above 40 GHz)  ............ 
 At  VHF and UHF, grid-controlled power tubes have been widely used in high-power radar  systems. They are capable of operation at frequencies as high as 1000 to 2000 MHz, but they  do not seem to be competitive to the linear-beam and crossed-field microwave tubes at radar  frequencies much above 450 MHz. At low-power levels, gridded tubes must compete with the  solid-stale transistor. 
 Lowsidelobe antennas requireunobstructed sitingifreflections 1'1'011\nearbyobjectsarcnottodegrade thesidelobe levels. Byemploying someoralloftheabovetechniques, theeffectofthesidelobe noisejammer canbesignificantly reduced. Someoftheabovetechniques canalsoreducethejamming that entersviathemainbeam.Theeffectsofmain-beam jamming canbefurther reduced by employing anarrow beamwidth tolimittheregionoverwhichthejamming appears.Ifthe mainbeamcannot hemadenarrow because ofconstraints ontheantenna size,anauxiliary antenna canbeemployed tocreateanotchinthemain-beam radiation pattern inthedirection ofthejammer. 
 267-278, Washington, Mar. 1-2, 1956. 32. 
 Geernaert  and W. J. Plant (eds.), Dordrecht, Netherlands: Reidel, 1988. 
 LIZE EITHER A SWITCHED 
 The plot for a single  pulse shows a single elliptically shaped region in which I x IZ is large. This is what would have  been expected from our previous discussions since a single measurement does not result in  ambiguity if the threshold is chosen properly. Range error is proportional to the pulse width 7,  while doppler error is proportional to l/r. 
 TIVE IF IT IS   THE VALUE IS NEGATIVE 4HE REPRESENTATION OF VOLTAGE IN S COMPLEMENT FORM  IS GIVEN BY   %   K 
 502–505, 1983.  93. L. 
 The two-way isolation provided by a typical fence with a straight edge might be about  40 dB, where the isolation is given by the ratio of the clutter signal in the absence of a fence to  that in the presence of the fence. The isolation is limited by the diffraction of the electromag­ netic energy behind the fence. Greater isolation than that provided by a straight-edged fence  can be had by incorporating two continuous slots near to, and parallel with, the upper edge of  the fence to cancel a portion of the energy diffracted by the fence. 
 Any use is subject to the Terms of Use as given at the website. Ground Echo.  GROUND ECHO  16.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Physical Optics Models.  Theories based on applications of the Kirchhoff- Huygens principle have been thoroughly developed.37,55,57–59 The Kirchhoff approxi - mation is that the current flowing at each point in a locally curved (or rough) surface  is the same as would flow in the same surface if it were flat and oriented tangent to the  actual surface. 
 Consider anIFamplifier withbandwidth BtFfollowed byaseconddetector andavideo amplifier withbandwidth 8,.(Fig.2.3).Theseconddetector andvideoamplifier areassumed toformanenvelope detector, thatis,onewhichrejectsthecarrierIrequency butpassesthe modulation envelope. Toextractthemodulation envelope, thevideobandwidth mustbewide enoughtopassthelow-frequency components generated bytheseconddetector, butnotsowide astopassthehigh-frequency components atorneartheintermediate frequency. Thevideo bandwidth Bt•mustbegreaterthanB1F/2inordertopassallthevideomodulation. 
 2ofthis series. But the technical achievement represented by the wartime development ofradar seems very nearly unparalleled. In terms ofthe time intervening between ‘the reception ofthe first radar signals and thelarge-scale useofradar inthewar, itisasif,seven years after thefirst faltering flight oftheWright brothers atKitty Hawk, the airplane had been developed into apowerful weapon ofwhich thousands were inconstant use. 
 613 6.30). Asingle Yagi oneach side isused asacommon transmitting and receiving antenna. The indication and themethod ofuse ofthis equip- ment arethesame asthose oftheASV Mark II. 
 Inthis manner, the points yielding the brightest returns are presented over a “base map” which shows the location ofthe aircraft and which partici- pates inany geometrical distortions ofthe radar presentation. Studies ofthis type ofpresentation show that (1)the location ofthe brightest N Fm. 3.27.—Boston, M2ss., ~th “three-tOm” presentation (Sec. 
 19.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 a variety of weather radars. However, it will be useful herein to include some of the  important characteristics of the Nexrad WSR-88D radar, which illustrate the perfor - mance of modern operational weather radars. Table 19.6 contains some of the more  relevant original Nexrad design features. 
 I. Skolnik, Introduction to Radar Systems , 3rd Ed., New York: McGraw-Hill, 2001, p. 117. 
 ● Small size and weight  Integration of active and passive components onto a  single chip results in high-density circuitry with multiple functions on a single  chip. Overall, the T/R module can be made much smaller than with discrete  components. The partitioning of T/R module circuit functions onto monolithic chips usually rep - resents a tradeoff among several design issues, and the resultant circuit configurations  represent a compromise among the goals of optimum RF performance, high levels of  integration, and fabrication yields that are consistent with processing capabilities of  GaAs MMICs. 
 Determining Optical Flow. Artif. Intell. 
 Avariable frequency can beadded tothesignal frequency and observations made when the sum frequency falls inthe pass band ofa resonant circuit. l“ariants ofthis idea sweep either j,orAjand observe when thetarget frequency falls inthepass band ofaresonant circuit. Any ofthese scanning devices greatly increases the time required to obtain the desired information. 
 M DIAMETER HIGH 
 For targets overhead, the angular accelerations required are quite  high. It is not practical to use such a mount, therefore, for tracking targets through the zenith,  as in the tracking of satellites. The rearrangement of the two axes as in (c) takes care of this  problem. 
 W. V . Rusch, “The current state of the reflector antenna art,” IEEE Trans. 
 Wilson and Schreiber have found that about 90% of the thunder - storms that occur in the Front Range of the Rockies in the summertime develop  over such “boundaries” between two different air masses. Since these boundaries  can be detected before any clouds are present and it is possible to infer the air mass  convergence (or coming together of two air masses) where insects are forced to  accumulate along these boundaries by doppler radar measurements, more precise  prediction of thunderstorm occurrence is possible. From the radar designer’s stand - point, such applications dictate the use of antennas with very low sidelobes (along  with low-phase noise transmitters and receiver components) and signal processors  having significant ground clutter rejection capability. 
 6.13. Energy from an  external source is accumulated in the energy-storage element at a slow rate during the inter­ pulse period. The charging impedence limits the rate at which energy can be delivered to the  storage element. 
 andpreselector filtermightnotbe insignificant. Insomenonradar applications, asforexample radioastronomy, mostofthese lossycomponents arenotnecessary asth'eyate 'inradar,sothatalownoisefigurefront-end canbeusedeffectively. However, anextremely lowreceivernoise-figure isnotusuallywarranted inradarbecauseoftheunavoidable RFlossesfoundinmostradars.Evenifthenoisefigureof thereceiver wereessentially 0dB.theoverallreceivernoise-figure wouldstillbeequaltothe lossesintheRFportionofthesystem. 
 WHAT LOOSER FORMATION WITH !QUA  !URA  4ERRA  AND 0!2!3/, 4AKE N TOGETHER  THESE  SIX ENVIRONMENTAL SATELLITES CONSTITUTE THE SO 
  
 1325–1334, November 1982. 16. A. 
 POWER HELIX TRAVELING WAVE TUBE  ALONG WITH AN INTEGRATED CIRCUIT POWER CONDITIONER  ALL IN A LIGHTWEIGHT PACKAGE )T CAN PROVIDE HIGH EFFICIENCY  WIDE INSTANTANEOUS BANDWIDTH  LOW NOISE  AND AVERAGE POWER LEVELS FROM SEVERAL TENS TO SEVERAL HUNDREDS OF WATTS )T IS SAID TO BE SMALLER AND LIGHTER THAN COMPARABLE 474 AND SOLID 
 INDUCED SURFACE CURRENTS 4HIS  PEAK  ORBITAL VELOCITY IS TAKEN TO BE THAT OF THE MAJOR WAVES AND MAY BE OBTAINED IN TERMS OF  THE SIGNIFICANT HEIGHT (  AND PEAK PERIOD 4  ` 3ECTION   FROM THE EXPRESSION   6ORB   O (  4 `    5 MS     4HE APPROXIMATE DEPENDENCE ON WIND SPEED  5 WAS FOUND BY SUBSTITUTING  (    HRMS  FROM %Q   ASSUMING A  FULLY DEVELOPED SEA   AND 4 ` FROM %Q  4O THIS  THERE MUST .   3%! #,544%2  £x°Ó£ BE ADDED A WIND 
 The lens may be omitted and the  correction applied at the phase shifters. With nonreciprocal phase shifters, a fraction  of the power reflected from the aperture will then be reradiated (as sidelobes) rather  than returned to the input. The amplitude distribution across the horn is given by the  waveguide mode. 
 20ofthis series. Movable HeightMarker.—The indices used fordetermining height on the RHI orthe type Edisplay are usually engraved mechanical ones. Often, however, amovable electronic index isprovided. 
 Motion- compensation equipment must include sensors capable of detecting the deviation of the flight path from a linear path. The output of these sensors is used in a variety of ways. For motion compensation proper, the received-signal phase must be adjusted to compensate for the displacement of the real antenna from the location of the ideal synthetic antenna being generated. 
 As will be discussed later, some ra- dar detection experiments with human observers have subsequently suggested that the constant of proportionality may not be exactly unity. However, North's analysis is theoretically correct for pulses of rectangular shape and for the defi- nition to be given in Sec. 2.3 for the noise bandwidth Bn. 
 BAND  KLYSTRON HAD A  -(Z BANDWIDTH AND A GAIN OF  D" WHEN ITS FOUR CAVITIES WERE SYNCHRONOUSLY TUNED  BUT WHEN STAGGER 
   
 Parameter selections are made on the basis of the best SNR in each nominal 50-nmi interval, but the selection is adjusted to come from the ad- jacent lower frequency to avoid an optimistic bias. Then parameter plots are made as a function of range. The variables shown are losses, frequency, noise, and elevation radiation angle. 
 65. Bogomolov et al.: Venera 15 and 16 Synthesized Aperture Radar in Orbit around Venus, /zv. Vyssh. 
 Johannessen, J.A.; Shuchman, R.A.; Digranes, G.; Lyzenga, D.R.; Wackerman, C.; Johannessen, O.M.; Vachon, P .W. Coastal ocean fronts and eddies imaged with ERS 1 synthetic aperture radar. J. 
 6/" - !%3!  ACTIVE ELECTRONICALLY SCANNED ARRAY!$  ANALOG 
 On the other hand, if the angle subtended by the paraboloid at the focus is large, more of  the radiation from the feed will be intercepted by the reflector. The less the spillover, the higher  the efficiency. However, the illumination is more tapered, causing a reduction in the aperture  efficiency. 
 E.. J. M. 
 BER OF MUCH HIGHER RESOLUTION SIMULTANEOUS hFINGERv BEAMS )T IS WELL KNOWN THAT THE CLASSICAL RESOLUTION OF AN ARRAY IMPROVES LINEARLY WITH APERTURE UP TO SOME LIMITING VALUE DETERMINED BY THE ENVIRONMENT (ORIZONTAL APERTURES OF n KM AND EVEN GREATER &)'52%   $IURNAL VARIATION OF (& NOISE  MEASURED IN D"7(Z  AT LATITUDE  3  LONGITUDE    %   .OVEMBER  &REQUENCY -(Z    
 4(% 
 The waveform tobedemodulated isapplied totheinput terminal ofthecir- cuit and the transformer isexcited byanunmodulated wave which is exactly inorexactly out ofphase with the carrier. Because ofgrid current, thetwo tubes will bias themselves tosuch apoint that they are turned ononly atthepeak ofthekeying wave- form; hence the device isapeak detector. The polarity oftherectified signal attheout- ~ putterminal willdepend upon which ofthetwo phase relationships exists. 
 Achoice oftwo time constants isavailable inthe grid circuit ofthis stage, 0.47 secand 2.4~sec. The longer one isnormally used; itgives good response tovery low video frequencies. The short time constant, when used, serves the same function against extended or c-w interference assimilar circuits doinaradar receiver (Sec. 
 The sense of the linear polarization of the energy radiated by the feed is  rnade tile same as the orientation of the wires of the parabolic reflector. The feed in the center  of the figure illuminates the parabolic reflector and the reflected energy is incident on a planar  mirror constructed as a twist reyector. As mentioned previously a twist reflector reflect5 the  incident energy with a 90" rotation of the plane of polarization. 
 A. A. Oliner and R. 
 A. Oliner and G. H. 
 Insupportofauto­ mobiletraffic,CWradarhasbeensuggested forthecontroloftrafficlights,regulation oftoll booths,vehiclecounting, asareplacement forthe"fifth-wheel" speedometer invehicletesting, asasensorinantilock brakingsystems, andforcollision avoidance. Forrailways, CWradar canbeusedasaspeedometer toreplacetheconventional axle-driven tachometer. Insuchan application itwouldbeunaffected byerrorscausedbywheelslip onaccelerating orwheelslide whenbraking.Ithasbeenusedforthemeasurement ofrailroad-freight-car'velocity during humping operations inmarshalling yards,andasadetection devicetogivetrackmaintenance personnel advance warning ofapproaching trains,CWradarisalsoemployed formonitorinf thedocking speedoflargeships.Ithasalsoseenapplication forintruder alarmsandforthe measurement ofthevelocity ofmissiles, ammunition, andbaseballs. 
 Geophys. Res., vol. 76, pp. 
 PENDENT TRACKING SYSTEM )T IS AN !IR 4RAFFIC #ONTROL 2ADAR "EACON 3YSTEM ARRAY ANTENNA THAT TRANSMITS AND RECEIVES NARROW AZIMUTH SUM  DIFFERENCE  AND GUARD BEAMS  ALL SHAPED IN ELEVATION )T REQUIRES A TRANSPONDER ABOARD THE AIRCRAFTS TARGETED  AS IT HAS LOW GAIN &)'52%   2EFLECTOR SHAPING &)'52%   %LIMINATION OF BLOCKAGE.   2%&,%#4/2 !.4%..!3   £Ó°Ó£ -ULTIPLE 
 F. Harwell: RASSR Array Comes or Age, Microwaves, vol. 11, pp. 
 When ,ti = 1, the  chi-square distribution of Eq. (2.40) reduces to the exponential, or Rayleigh-power, distribu-  tion of Eq. (2.39~) that applies to Swerling cases 1 and 2. 
 ANGLE OF INCIDENCE FIG. 12.17 Examples of the variation with angle of incidence of the number of independent samples for a scatterometer. measuring beamwidth or pulse width usually encompasses signals from regions having values for cr° many decibels apart. 
 REFERENCES 1. Headrick, J. M., and M. 
 Temporal coherence applies primarily to the scene. In order for the two signals to  act as an interferometric pair, their respective phase structures must be relatively stable  over the time interval between satellite observations. In short, there must exist mutual  coherence between the two scattering signals, even though they are observed at differ - ent times. 
 REFLECTION LOSS IS ADDED  AND REQUIRED OPERATION AT A LOWER FREQUENCY INCREASES LOSS 4HE JAGGED CURVE IN THE TRANSI 
 J. Geopl1ys. Re.~ .•  vol. 
 133. M. Sachidananda and D. 
 DETECTOR OUTPUT IS FROM  
 LOOK 3!2 AZIMUTH RESOLUTION  IS PROPORTIONAL TO ONE OVER THE DOPPLER BANDWIDTH GENERATED BY  THE AZIMUTH BEAM 
 1  I ' Range gate  No.2 Second  threshold  Binary  counter Target  Count pulse  sampler  Figure J0.7 Block diagram of a binary moving window detector, or binary integrator. DF!ECTION OF RADAR SIGNALS IN NOISE 389  gates, and lhc Is and Os from the last II sweeps are stored and counted in the binary counter. If  there are at least m ls within the lasf II sweeps, a target-is said to be present. 
 Hence fmT = 0.2, which is beyond the region of noise correlation. An unmodulated CW radar must contend with clutter almost down to zero range. Without the correlation effect, this would generally be impossible. 
 Thompson, “The correction of I and Q errors in a coherent  processor,” IEEE Trans ., vol. AES–17, no. 1, pp. 
 Acker, A. E.: Eliminating Transmitted Clutter in Doppler Radar Systems, Microwave /., vol. 18, pp. 
 This property js useful insuch applications asthe demodula- tion ofacarrier wave modulated byasynchro. Aspointed out inSec. 13.4, the output signal J.E& atagiven phase oftheinput signal has oppo- Flo. 
 (13.1) and having a phase velocity C = 2ir x flK equal to the wind speed U. By using Eq. (13.1), the period T and wavelength A thereby defined take the form T = 0.64*7 A = Q.64U2 (13.5) where U is in meters per second. 
   !)2"/2.% -4)  Î°£x )N ORDER TO TREAT SCANNING MOTION IN THE FREQUENCY DOMAIN  THE APPARENT CLUTTER  VELOCITY SEEN BY THE SCANNING ANTENNA IS EXAMINED TO DETERMINE THE DOPPLER FREQUENCY  %ACH ELEMENT OF AN ARRAY OR INCREMENTAL SECTION OF A CONTINUOUS APERTURE CAN BE CON 
 17.10 between fixed ground stations since they can bepermanently oriented in the correct direction. Very high, even microwave, frequencies are desirable forsuch applications since directional antennas can then be small, rugged, and easily constructed and installed. Atleast one micrw wave equipment has been successfully used inexperimental tests (Sees. 
 It is not  practical to provide a time-delay network at each element in a phased array because FIGURE 13.25  Center-fed series array ( after J. Frank79 © Artech House  1972 ): (a) center-fed series feed and ( b) gabled phase due to feed Feed CW Bandwidth (%) Pulse Bandwidth (%) Equal line length Beamwidth 2 × beamwidth End-fed series 1 1+×  λ λgbeam width2 1+×  λ λgbeam width Center-fed series λ λg×beam width 2λ λg×beam width Space-fed (optical) Beamwidth 2 × beamwidth * After Frank79 NOTE: All beamwidths are in degrees and refer to the broadside beamwidth:  lg = guide wavelength and l = free- space wavelength.TABLE 13.2  Bandwidth Criteria for Several Feed Networks* ch13.indd   42 12/17/07   2:40:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 7. R. K. 
 WAVE GYROTRONS OFTEN HAVE TO BE GENERATED BY SUPERCONDUCTING MAGNETS 4HE GYROTRON WITH A SINGLE CAVITY OPERATES AS AN OSCILLATOR )T IS SOMETIMES CALLED  A GYRO 
 The shallow reflector is easier to support and  move mechanically since its center of gravity is closer to the vertex, but the feed must be  supported farther from the reflector. The farther from the reflector the feed is placed, the  narrower must be the primary-pattern beamwidth and the larger must be the feed. On the  other hand, it is difficult to obtain a feed with uniform phase over the wide angle necessary to  properly illuminate a reflector with smallflD. 
 PENDENTLY DETERMINED BY THE PULSE COMPRESSION WAVEFORM DESIGN PARAMETERS ! NOTE OF CAUTION IS IN ORDER WHEN CONSIDERING PULSE COMPRESSION FOR METEORO 
 (f,·om Jolmson103 Courtesy Proc. IEEE.) . 316 INTIH)l)UCTION TO RADAR SYSTEMS  sampling signal. 
 2.9. For Tag = 36 K and Ttg = Tta = 290 K, this becomes 0.876 Ti - 254 Ta = + 290 (2.35« La and if L0 = 1 (lossless antenna), it further simplifies to Ta = 0.876 JJ + 36 (2.35c) Transmission-Line Noise Temperature. Dicke26 has shown that if a passive transducer of noise bandwidth Bn connected in a cascade system is at a thermal temperature Tt and if its available loss factor is L, the thermal-noise power available at its output terminals is Pno = kTfln(\ - UL) (2.36) A transmission line is a passive transducer. 
 Any use is subject to the Terms of Use as given at the website. Civil Marine Radar.  CIVIL MARINE RADAR  22.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 Because precipitation clutter is distributed in a relatively uniform manner, passing  the received waveform through a differentiator gives prominence to targets embedded  within the clutter by ensuring that the average clutter level is kept well below satura - tion. The differentiator has minimal effect on normal targets because of their small  extent in the time domain. 
 SOURCE INTERFEROMETER WHOSE ANTENNAS USUALLY ARE .   %,%#42/.)# #/5.4%2 
 the first grating lobe (rl = fI I) does not appear in real space since sin 0 > I, which cannot be.  Grating lobes appear at +90° when ti = 1. For a nonscanning array (which is what is con-  sidered here) this condition (rl = A) is usually satisfactory for the prevention of grating lobes. 
 Figure 12.7 shows such a set of constant- doppler-shift contours. The spectrum of fading can be calculated by a slight rearrangement of the ra- dar equation (12.1). Thus, if Wr(fd) is the power received between frequencies fd and fd + dfd, the radar equation becomes U7,fw l f PfitAr</>dA dfd r/>,G,Ara0/ dA\Wr(fd}dfd = I = I - — (12.12) (4<7r)2j R4 (47T)2 J R4 \ dfj Illuminated area between fd and fd + dfd This is an integral in which the area element between/^ and fd + dfd is expressed in terms of coordinates along and normal to the isodops. 
 TO 
 ● Three of the five filters will reject fixed clutter and respond to moving targets. Two  filters will respond to targets at zero doppler and its ambiguities. (With good fixed  clutter rejection filters, it takes two or more coherent filters to cover the gap in  response at zero velocity.) With the above considerations, a filter bank can be constructed. 
 Figure 6a shows the result of sorting and the red line represents W=67. Second, calculate the mean value μand the standard deviation σfor all remaining amplitudes, which are the noise. The red line shown in Figure 6b isμ=0.0954. 
 Pierson and M. A. Donelan18 © American  Geophysical Union 1987 ) FIGURE 15.6  Sea clutter from a tower platform with power-law wind- speed dependence defined by linear regression (angle of incidence = 90°  grazing angle) ( after A. 
 Complex baseband   signal 8. Decimate by two   (Re-sample @ 50 MHz) 9. Complex decimated   baseband signal–75 MHz FIGURE 25.11  Digital downconversion architectureIFLPF LPFADCI QANALOG   DIGITAL NCO   (75 MHz)–SIN  COS 100 MHz  CLOCK2 2I Q50 MCSPS DDC1617 1717 17 ch25.indd   9 12/20/07   1:39:54 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The organization that employs radar data may bealmost entirely mechanized and automatic, asis,forexample, theArmy system forradar antiaircraft fire control. Inthis system, the azimuth, elevation, and range ofatarget are transmitted directly and continuously from the radar toanelectrical computer. The computer solves the fire-control problem, determines the future position ofthe target, and transmits azimuth, elevation, and range (fuze time) information tothe guns ofthe battery. 
  O ARITHMETIC AND OVERFLOWS ARE AUTOMATICALLY TAKEN CARE OF  SINCE A  O PHASE SHIFT IS THE SAME AS O &OR EXAMPLE  ASSUME WE HAVE A  
 Conﬂicts of Interest: The authors declare no conﬂict of interest. References 1. Brusch, S.; Lehner, S.; Fritz, T.; Soccorsi, M.; Soloviev, A.; van Schie, B. 
 10.4 Digital matched filter, (a) Correlation processor, (b) Stretch processor.REFERENCE WRVEFORMFFT WITH ZERO FILL MULTIPLY LIKE COMPONENTSINVERSE FFTCOMPRESSED PULSE RECEIVED WRVEFORMFFT U) RECEIVED WRVEFORM DELRYED WRVEFORM GENERRTORSPECTRUM RNRLYZER OR REDUCED BRNDWIDTH CORRELRTION PROCESSORCOMPRESSED PULSE . stretch processor for a linear-FM waveform. The delayed waveform has a band- width that is equal to or somewhat less than the transmitted waveform and a length that exceeds the duration of the transmitted waveform. 
 Therefore, we can remove the noise out of the RCS curve. Then we propose a denoising method for the RCS curve. The result of simulations shows that aspect entropy is more accurate after denoising. 
 Blair, “IMM algorithm for tracking targets that maneuver through coordi - nated turns,” SPIE, Signal and Data Processing of Small Targets , vol. 1698, pp. 236–247, 1992. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.48  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 Reciprocal Mixing.  Analog receivers of heterodyne design generally involve a  number of local oscillators for signal mixing and perhaps a waveform generator used  to implement a matched filter. 
 ACFARmaybeobtained byobserving thenoiseorclutterbackground inthevicinilYof thetargetandadjusting thethreshold inaccordance withthemeasured background. Figure 10.11illustrates thecell-averaging CFARwhichutilizesatappedde}.1y-line tosamplethe rangecellstoeithersideoftherangecellofinterest,ortestcell.T11eoutputofthetestcellisthe radaroutput.Thespacingbetwe-m thetapsisequaltotherange;esolution. Theoutputsfrom thedelaylinetapsaresummed. 
 SION HAS LARGELY BEEN REPLACED BY PULSE COMPRESSION USING DIGITAL SIGNAL PROCESSING  . È°{  2!$!2 (!.$"//+  )N THE CASE OF VERY WIDEBAND WAVEFORMS  ANALOG STRETCH PROCESSING SEE 3ECTION   MAY  BE USED TO REDUCE THE SIGNAL BANDWIDTH BEFORE SUBSEQUENT DIGITAL SIGNAL PROCESSING 4HE RECEIVER DISCUSSED HEREIN FOCUSES ON THOSE FUNCTIONS THAT PROVIDE ANALOG PRO 
 Thedecor­ relation timesat95GHzvariedfromabout3.4msat5mm/hrainrateto1.4msat100mm/h. AtXbandthedecorrelation timeswerelongerandvariedfrom14msat5mm/hto5.4msat 100mm/h. Utilityofmillimeter waves.Experimentation withmillimeter wavelength radiation and microwave radiation bothdatebacktotheendofthenineteenth century. 
 145. Sensors 2019 ,19, 2921 For the convenience of analysis, we take the deformation monitoring accuracy at h=100 m as the example. Referring to the curve in Figure 17, the deformation monitoring accuracy of the traditional ArcSAR imaging algorithm is 1.78 ×10−4m. 
 pp. 864 866. November, 1974. 
 Dielectrics are generally poor conductors of heat. Unless materials are of  low loss and can operate at elevated temperatures,63 dielectric lenses such as the Luneburg  lens are more suited to receiving, rather than transmitting, applications.  The Luneburg principle may also be applied to a two-dimensional lens which generates a  fan beam in one plane. 
   
 At C band and higher frequencies,  most of the signal returned from trees is usually from the upper and middle branches  when the trees are in leaf,46–50 although in winter the surface is a major contributor to  the signal. At L band, and especially at VHF, the signal penetrates farther, so trunks and  the ground can be major contributors even when the trees are leafed out.51 Additional problems occur near grazing incidence.17,52 Because of the low angle  with the surface, shadowing frequently occurs—some parts of the target are obscured  by intervening projections such as hills and buildings. Parts of the area that are some - what elevated have the signal modified by the effect of multipath interference between  FIGURE   16. 
 1968.  JO. Ridenour. 
 The  precision of an ocean-viewing altimeter is proportional to the radar’s range resolution  and inversely proportional to the square root of the number of statistically independent  measurements (looks) combined for each data point. Ocean-viewing altimeters, in  general, have large SNR. Thus, bandwidth and looks become the driving requirements  on system design. 
 15, 1964. 86. Peake, W. 
 5.4~ in time so as to  cover the entire pulse-repetition period (Fig. 5.46). This is possible only in a range-gated  rcccivcr. 
 TIME PARALLEL 
 It should be appreciated, therefore, that radio alti-  meters of this type do not depend on pulse and echo, but  on frequency difference. A continuous-wave signal is  continuously, rhythmically changed slightly in fre-  quency, and this is fed into a receiver as well as into the  frequency-modulation side of the transmitter. The echo  is received back from the ground, and its frequency  difference is measured from that of the signal which is  at that same instant being transmitted. 
 -Phe attenuation produced by icc particles in the atmospl~erc, whether occurring as hail.  snow, or ice-crystal clouds, is mucli less than that caused by rairl of an equivalent rate of  pre~ipitation.'~ Gunn and East" state that the attenuatio~i in snow is  .  where r = snowfall rate (rnm/ll of nielted water content). 
 The upper  figure assumes uniform amplitude weighting ( -13.2 dB first sidelobe) and the lower figure  shows the effect of Chebyshev weighting designed to produce equal sidelobes with a peak value  of -25 dB. It is found that doubling to 16 the number of pulses in the filter bank does not  offer significant -advantage over an eight-pulse filter.30 More pulses do not necessarily mean  more gain in signal-to-clutter ratio, because the filter widths and sidelobe levels change relative  to the clutter spectrum as the number of pulses (and number of filters) is varied. If the sidelobes  of the individual fllters of the doppler filter bank can be made Jow enough, the inclusion of  the delay-line canceler ahead of it might not be needed. 
 24 Reduced dimension STAP architectures ch03.indd   26 12/15/07   6:03:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 
 By isotropic scattering is  meant that the radar cross section of each object is independent of the viewing aspect. The  separation I is assumed to be less than 1x12, where c is the velocity of propagation and r is the  pulse duration. With this assumption, both scatterers are illuminated simultaneously by  the pulse packet. 
 STATE CONDITIONS ARE ASSUMED IN THIS DERIVATION  THUS THE CONDITION FOR  ORTHOGONALITY IS   %[R D  ]       WHERE %[] IS THE EXPECTATION   D IS THE ESTIMATION ERROR  AND   IS THE COMPLEX CONJUGATE  4HE ADAPTIVELY WEIGHTED ESTIMATE IS OBTAINED BY WEIGHTING THE R ECEIVED SIGNAL VECTOR  BY THE ESTIMATE OF THE ADAPTIVE WEIGHTS  }}gSW R     7ITH D DEFINED AS THE DESIRED SIGNAL A MAIN 
 141, issue 2, pp. 75–82, 1994. 55. 
 IRE, vol. 47, pp. 430-435, March, 1959. 
 Doppler-Limited Clutter Cell Area. The doppler-limited clutter cell area (A,.),, has been determined by numerical integration techniques when it is bounded by a range resolution cell.51'89 No convenient algebraic expression has been developed for the cell area since the doppler cell size and orientation with respect to the baseline change as the transmitter and receiver velocity vectors and look angles change. In the special case where the transmitter and receiver velocity vectors are equal and the bistatic angle is large, the isorange and isodoppler contours are essentially parallel, creating very large clutter cell areas.59 25.6 DOPPLERRELATIONSHIPS Figure 25.5 defines the geometry and kinematics for bistatic doppler when the target, transmitter, and receiver are moving. 
 TERN PROPORTIONAL TO CSC P  WHERE P IS THE ELEVATION ANGLE )N PRACTICE  THE WELL 
 15.16) as  the cross section of a patch with local  grazing angle y  = s  0 + a , where a  is the local  wave slope and y 0 is the mean grazing angle. For the simple one-dimensional case,  this quantity is averaged over the sea slope angle distribution p(a ), yielding  σ ψ σ ψ α α α0 0 0 ( ) ( ) ( ) = + −∞∞ ∫p d  (15.18) For a more general two-dimensional sea, the local grazing angle is a function of the  slopes in and normal to the plane of incidence, so for each polarization p, the angle  function Fp(y ) in s  0 (y ) becomes a complex mixture of the angle functions of both  polarizations. Plant104 provides a comprehensive discussion of this model. 
 Initially, an aircraft of opportunity has the  highest association probability; however, a firm decision is not made because Pmax  does not exceed Pnext by the probability margin. After the 14th DF detection, the  emitter is firmly correlated with the control aircraft. However, at the 18th DF detec - tion, a very bad detection (outlier) is made, and the firm correlation is downgraded  to a tentative correlation if limiting is not used. 
 ANGLE DEPENDENCE OF THE SFERICS FIELD IS INEVITABLE EXAMINATION OF MAPS PRODUCED BY SATELLITES   INDI 
 In order to carry out an accurate comparison, we transferred the generated Line of Sight (LOS) deformation into vertical displacement according to the equation SLOS=Svcosθ, and extracted the eight dates of the measurement data that coincided temporally with our SAR acquisition dates. The total reference point of leveling and all the SBAS processing methods were the same pixel, which was selected according to our in situ investigation and registered deformation material collection. The comparison results are shown in Figure 13, where the blue solid squares represent deformation results obtained by the rheological model, and the purple solid triangles illustrate the linear model results. 
 Phased-array developments, which do scan electronically, also  foresee fairly good sidelobe performance; see the following references36–40 for a  view of relevant developments. Two additional techniques to prevent jamming from entering through the radar’s  sidelobes are the so-called sidelobe blanking (SLB) and sidelobe canceler (SLC). An  example of the practical effectiveness of the SLB and SLC devices is presented in the  literature, where the plan position indicator (PPI) display is shown for a radar, subject  to an ECM, equipped with and without the SLB and SLC systems.31 Other discrimination means are based on polarization. 
 The SBX platform that it sits on  stands more than 250 ft tall and displaces more than 50,000 tons. It consists of a semi- submersible oil production platform, topped with the XBR. XBR is the primary payload  on the semi-submersible platform supporting the Ground-Based Midcourse Defense  (GMD) phase of the Missile Defense Agency (MDA) Ballistic Missile Defense System  (BMDS). 
 SEQUENCE IS LOSS DUE TO BLOCKAGE AND DEPENDS UPON THE BLOCKED ELECTRIC FIELD TO MAIN ELECTRIC FIELD RATIO   % B%M  WHICH  IN TURN  IS DETERMINED FROM THE RATIO OF BLOCKED POWER  TO TOTAL POWER ON THE MAIN REFLECTOR   0B0M  AND RATIO OF THE GAIN OF THE BLOCKING OBJECT  TO THE GAIN OF THE MAIN REFLECTOR  'B'M  % %0 0' 'B MB MB M¤ ¦¥³ µ´    . 
 8.8.  7.9 RADOMES14,103,11s.122-124  Antennas for ground-based radars are often subjected to high winds, icing, and/or temperature  extremes. They must be sheltered if they are to continue to survive and perform under ad vase  weather conditions. 
 FRAME DESIGNERS AND NAVAL ARCHITECTS "UT THERE IS NO POINT IN CONSIDERING SHAPE CONTROL UNLESS A SPECIFIC THREAT DIRECTION CAN BE IDENTIFIED IN AZIMUTH OR ELEVATION OR BOTH )F ALL DIRECTIONS ARE EQUALLY LIKELY  THEN THE ADVANTAGE OF CHOOSING FAVOR 
 A slightly more complex model than the two-scatterer target considered above is one  consisting of rnatiy individual scatterers, each of the same cross section, arranged uniformly  along a line of length L perpendicular to the line of sight from the radar. The resultant cross  scctiori froin sucll a target is assumed to behave according to the Rayleigh probability distribu-  tion. Tlie probability of the apparent radar center lying outside the angular region of LIR  radians (in one tracking plane) is 0.134, where R is the distance to the target.j2 Thus 13.4 per-  cent of the time the radar will not be directed to a point on the target. 
 Figure 11.17 repre- sents the Radar backscattering diagram of an airplane.     Figure 11.17  Measured Radar backscattering diagram of an airplane (B 26), λ = 10 cm,  horizontal polarization.  The fluctuations of σ amount up to 20 dB. 
 TIME FREQUENCY MODULATION  FUNCTION OF A NONSYMMETRICAL .,&- WAVEFORM OF BANDWIDTH " IS    FT "T 4+NT 4N N  SIN   ¤ ¦¥³ µ´  £ P    &)'52%    3YMMETRICAL AND NONSYMMETRICAL NONLINEAR 
 103 Alberto Michelini, Francesco Coppi, Alberto Bicci and Giovanni Alli SPARX, a MIMO Array for Ground-Based Radar Interferometry Reprinted from: Sensors 2019 ,19, 252, doi:10.3390/s19020252 ..................... 119 Yanping Wang, Yang Song, Yun Lin, Yang Li, Yuan Zhang and Wen Hong Interferometric DEM-Assisted High Precision Imaging Method for ArcSAR Reprinted from: Sensors 2019 ,19, 2921, doi:10.3390/s19132921 .................... 131 Yang Fang, Baoping Wang, Chao Sun, Shuzhen Wang, Jiansheng Hu and Zuxun Song Joint Sparsity Constraint Interferometric ISAR Imaging for 3-D Geometry of Near-Field Targets with Sub-Apertures Reprinted from: Sensors 2018 ,18, 3750, doi:10.3390/s18113750 .................... 
 IRE.) Theclutterspectrum canalsobeexpressed intermsofanrmsclutterfrequency spread (I,. inhertzorbythermsvelocity spread(Jvinm/s.46ThusEq.(4.18)canbewritten ((2)((2).2)W(f)=Woexp-2(J;=Woexp-'8(J~ (4.19) whereWo=Igol2,(Jc=2(Jv!).,).=wavelength =clfo,andc=velocity ofpropagation. Itcan beseenthata=c2/8(J~.Thermsvelocity spread (Jvisusuallythepreferred method for describing theclutterfluctuation spectrum. 
 , vol. GE-26, pp. 144–152, 1988. 
 Whicker, L. R., and C. W. 
 Zoughi, “Sources of scattering from vegetation canopies at   10 GHz,” IEEE Trans. , vol. GE-23, pp. 
 (The radar might rotate around the fixed object, or the radar can be fixed and the object rotated about its own axis.) Range resolution is not necessary with the coherent tomographic radar method. As mentioned earlier, comparison of the scattered fields for different polariza- tions provides a measure of target asymmetry. It should be possible to distinguish targets with different aspect ratios (shapes), as for example, rods from spheres and spheres from aircraft. 
 The feedback connections that provide the maximal-length sequences may be determined from a study of primitive and irreducible polynomials. An extensive list of these polynomials is given by Peterson and Weldon.26 Table 10.5 lists the length and number of maximal-length sequences obtainable from shift-register generators consisting of various numbers of stages. A feed- back connection for generating one of the maximal-length sequences is also given for each. 
 No. OSSA-I-SS, Jan. 19, 1988. 
  
 V . Virts, and M. F. 
 , /"  Ê-/  , - 3PECTRUM USE ASPECTS OF ALL RADARS  INCLUDING FREQUENCY BAND OF USE AND 2& EMISSION CONSTRAINTS  ARE CONTROLLED BY THE )45  &OLLOWING )45 REQUIREMENTS  MARINE RADARS  ARE PERMITTED TO OPERATE IN THE  TO  '(Z BAND 8 BAND  AND IN THE  TO  '(Z BAND 3 BAND . 
 A systematic method for calculating the gains depending on the situation is the  FIGURE 7.27  Example of the tuning of an a-b radar range-tracking filter by selecting the gain that mini - mizes total error (radar parameters: range accuracy, 50 meters; update interval, 2 seconds; target parameter,  1 g unknown acceleration; gain relation, [ b = a2/(2 - a)]) ch07.indd   27 12/17/07   2:14:00 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
  
 L. Drake, and C. M. 
 SCAN RADARS PROVIDES SIMILAR CONSTANT ANGLE ERROR  SENSITIVITY /NE MAJOR LIMITATION IN CONICAL 
 TIONS ARE NOT ALWAYS SATISFIED  IT IS COMMON TO USE THE TERM  : E  THE EFFECTIVE REFLECTIVITY  FACTOR  IN PLACE OF  : 7HEN :E IS USED  IT IS GENERALLY UNDERSTOOD THAT THE ABOVE CONDI 
 (ORIZON 2ADAR   IN 2USSIAN  2ADIO I SVYAZ    !LSO A TRANSLATION BY 7 & "ARTON  .ORWOOD  -! !RTECH (OUSE    2 ! 'REENWALD  + " "AKER  2 ! (UTCHINS  AND # (ANUISE  h!N (& PHASED ARRAY RADAR FOR  STUDYING SMALL 
 E.: Another type of complementary series, IEEE Trans., vol. AES-Il, pp. 916-920, September 1975. 
 77. Sirigcr. K. 
 (8.28) with Pe= l. ~2 = O. and c52 small. 
 One reason is the broad elevation beamwidths. (The rms error of an angle  measurement is proportional to the beamwidth.) Another limitation is the effect of multipath  due to reflection from the earth's surface, also a consequence orthe broad fan beams. The effect  of multipath is similar lo the cffcc:t of glint discussed in Sec. 
  
 The excited synchro isrotated insynchronism with the scanner, the second being manually oriented toselect the desired sector (Sec. 13.4). Asmany asfive orsix B-scopes with independent sector selection can beoperated inthis way from asingle oscillator and antenna synchro. 
 16.5, 35, and 95 GHz, /974 IEEE  A111!wws and Propagation Society Symposium, June l0-12. 1974, pp. 319-322, IEEE Cat. 
 UHF is a good frequency for Airborne  Moving Target Indication (AMTI) radar in an Airborne Early Warning Radar (AEW),  as discussed in Chapter 3. It is also a good frequency for the operation of long-range  ch01.indd   15 11/30/07   4:34:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 4 5. The digital processor, however, does not experience degradation due to time jitter of  the transmitted pulse since the system clock controlling the processor timing may be started  from the detected rf envelope of the transmitted pulse.  Internal fluctuation of clutter.48 Although clutter targets such as buildings, water towers, bare  llills. 
 This is understandable, if one multiplies the  matrix product in Equation (11.11) out and arranges the quadratic matrices in vector form, as  is presented in Equation (11.12).  All measurements result from a product Rξη . Tξη of the  transmitting and receiv ing path. 
 Monopulse. In general, the term monopulse refers to a radar technique to estimate the angle of arrival of a target echo resulting from a single-pulse trans- mission by using the amplitude and/or phase samples of the echo in a pair of si- multaneously formed receive beams (Sec. 18.3). 
 To obtain time sidelobes of 40 dB be- low the compressed pulse, the amplitude and phase tolerances are 2 percent and 1.15°, respectively. Equalization. The transversal filter51'52 is widely used in the equalization of cumulative amplitude and phase distortion. 
 5.6TRACKING INRANGE3,55-58 Inmosttracking-radar applications thetargetiscontinuously trackedinrangeaswellasin angle.Rangetracking mightbeaccomplished byanoperator whowatches anA-scope or J-scopepresentation andmanually positions ahandwheelinordertomaintain amarkerover thedesiredtargetpip.Thesettingofthehandwheel isameasure ofthetargetrangeandmaybe (;onverted toavoltagethatissupplied toadataprocessor. Astargetspeedsincrease, itisincreasingly difficult foranoperator toperform atthe necessary levelsofefficiency overasustained periodoftime,andautomatic tracking becomes anecessity. Indeed,therearemanytracking applications whereanoperator hasnoplace,asin ahomingmissileorinasmallspacevehicle. 
 When the target ismoving, its range will change from pulse topulse and afluctuating output signal results from the corresponding change inthe phases traversed bythe oscillators during the echo-time.. SEC.163] APRACTICAL MTI SYSTEM 633 Asimple laboratory type ofdelay line isshown inFig. 16.10. 
 Richard, “Digital I/Q,” Section 3.7.3 in Fundamentals of Radar Signal Processing ,   New York: McGraw-Hill, 2005. 54. L. 
 Thefirstdetection ofaircraftusingthewave-interference effectwasmadeinJune,1930,by L.1\..HylandoftheNavalResearch Laboratory.l Itwasmadeaccidentally whilehewas working withadirection-finding apparatus locatedinanaircraftontheground.Thetransmit­ teratafrequency of33MHzwaslocated2milesaway,andthebeamcrossedanairlanefrom anearbyairfield.Whenaircraftpassedthrough thebeam,Hylandnotedanincrease inthe received signal.Thisstimulated amoredeliberate investigation bytheNRLpersonnel, butthe workcontinued ataslowpace,lackingofficialencouragement andfundsfromthegovern­ ment.although itwasfullysupported bytheNRLadministration. By1932theequipment was demonstrated todetectaircraftatdistances asgreatas50milesfromthetransmitter. TheNRL workonaircraftdetection withCWwaveinterference waskeptclassified until1933,when severalBellTelephone Laboratories engineers reported thedetection ofaircraftduringthe courseofotherexperiments.5TheNRLworkwasdisclosed inapatentfiledandgrantedto Taylor,Young,andHyland6ona"SystemforDetecting ObjectsbyRadio."Thetypeofradar described inthispatentwasaCWwave-interference radar.Earlyin1934,a6O-MHz CW wave-interference radarwasdemonstrated byNRL. 
 The process of DEM image from slant range to ground range in linear scanning GBSAR is generally achieved in Cartesian coordinate system. This is because the range direction and azimuth direction of 139. Sensors 2019 ,19, 2921 the linear scanning GBSAR are along the coordinate axes of the Cartesian coordinate. 
 Complete reflection atthe end ofthe line, such aswould beexpected from anopen circuit orashort circuit, results inzero voltage athalf-wave intervals and aVSWR of infinity. The mismatch may also beexpressed asapower ratio (PSWR), orindecibels. The relations between these three measures are PSWR =(VSWR)Z SWR, db=10log,, (PSWR). 
 IEEE.)  comb fingers, or electrodes, or the IDT are spaced one-half the wavelength of the acoustic  signal propagating along the SAW material.22 Thus the frequency response of the delay line  depends on the periodicity of the electrode spacings. A dispersive delay line for linear FM  pulse compression is obtained with a variable electrode spacing, as illustrated in Fig. 11.17 a or  b. 
 14.1 is not always an absolute requirement. In both mea - surement and analysis, the radar receiver and transmitter are usually taken to be in the  far field of the target (discussed in Section 14.4), and at that distance, the scattered field  Es decays inversely with the distance R. Thus, the R2 term in the numerator of Eq. 
 or mountains produce echo signals that are constant in both phase and amplitude as a  function of time, there are many types of clutter that cannot be considered as absolutely  stationary. Echoes from trees, vegetation, sea, rain, and chaff fluctuate with time, and these  fluctuations can limit the performance of MTI radar.  Decause of its varied nature, it is difficult to describe precisely the clutter echo signal. 
 If the MTI system were incapable of displaying an air - craft while it was over the mountain face, it would display the aircraft on the next scan  of the antenna because the aircraft would have moved either farther or nearer. The  PPI does not have a resolution that approaches the resolution of the signal processing  circuits of this radar. Thus, the apparent extended clutter has many weak areas not  visible in these photographs, where targets could be detected by virtue of an MTI  radar’s interclutter visibility (defined in Section 2.5). 
 vol. AP-20, pp. 129-136, March, 1972. 
 Michiyatr Rtidirrtiotr Llrh. Kept., 2591 - 1 -H on  Contract AF' 19(604)- 1949. July, 1959. 
 2.44  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 there will be a voltage residue from the cancelers that is proportional to the slope   a and inversely proportional to g  − 1, where g  is the ratio of the intervals. The appar - ent doppler frequency of the residue will be at one-half the average repetition rate  of the system and thus will be at the frequency of maximum response of a binomial- weight canceler. The rate of change of phase or amplitude of clutter signals in a scanning radar is  inversely proportional to the hits per beamwidth, n. 
 (In a magic T the LO  would be applied to the H-plane arm, and the RF signal would be applied to the £-plane arm. Y  The diode mixers would be mounted at equal distances in each of the collinear arms.) The  two diode mixers should have identical characteristics and be well matched. The IF signal is  LO RF  t J  RF  IF ou!pul Figure 9.2 Principle of the balanced mixer based on the magic T. 
 OND TO A GUARD ANTENNA THE  3 AND 'UARD CHANNEL IN &IGURE   RESPECTIVELY   TO  DETERMINE WHETHER A RECEIVED SIGNAL IS IN THE MAIN BEAM OR THE SIDELOBES n 4HE  GUARD CHANNEL USES A BROAD 
 C.: Rairi E3Tects on Radomes and Antenna Reflectors, " Design and Construction of Large  Steerable Aerials." IEE (Lottdon) Cor!fererence P~rhlication no. 21, pp. 148-151, 1966. 
 I.: Large Antenna Systems, chap. 28 of "Antenna Theory, pt. 2," K. 
 SO K;ir,y\tc.k. A J.: ~l'r;irtsii.t~t Hc.;l,o~~sc of 7'rncki1\g I:iltcrs with Ka~ldoriily Intel-ruptcd Data. IEEE  11.trrr.c. 
 BATCH BASIS 4HE BATCH 
 Summing these  components yields the virtual doppler velocity at the peak of the clutter spectrum for  the particular case of a vertically polarized X- or C-band  radar looking upwind at low  grazing angles:  Vvir = 0.25 + 0.18 U (m/s) (15.11) (As noted earlier, care must be taken whenever wind speed is used to parameterize  a process that depends on waveheight. There is an unambiguous relation only for a  fully developed sea in the absence of swell.) The remaining properties of the clutter  spectrum can now be discussed in terms of Vorb and Vvir . For example, the spectral  peak for horizontal  polarization follows a similar linear dependence on U, only with  a coefficient lying somewhere between 0.20 and 0.30, as may be noted in the sketch  shown in Figure 15.14. 
 Since the range of coverage is dependent on the aperture with  1/a2, there are in practice, even aside from the complexity of the processing, limits placed upon  the resolution.  For the derivation of resolution there also exist  other approximations.   10.6 Analysis Procedures   When describing possible analysis methods it is useful to regard the progression of the Dop-pler frequencies according to Equation (9.14). 
 Third, the absolute value of each pixel as the RCS amplitude is used to obtain the RCS curve of each pixel. Finally, the aspect entropy of each pixel is calculated. Details of the procedure are explained in the text below. 
 A. Schaefer, F. W. 
 R. Duncan: Upwind-Downwind-Crosswind  Sea-Clutter Measurements, Naval Research Laboratory Report 6881, Washington, D.C., Apr. 14, 1969. 
 Jonas, and L Alexander, The Electronic Chart , 2nd Ed,  Lemmer, Netherlands: GITC, 2006. 26. “Operational use of AIS,” Model Course 1.34, International Maritime Organization, London, 2006. 
 Although only one threshold is described, two are actually used  before hits and their corresponding discriminants are passed to the track files. All low  threshold hits are passed to activity counters. As complex as this thresholding scheme  seems to be, it is very detection power efficient. 
 FIGURE 13.40  Deterministic antenna pattern with and without  nulling for a 25-element linear array. Interfering source is located at  +21 degrees. ch13.indd   59 12/17/07   2:41:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 This switching, thedecoding ofthemodulator pulse, and the derivation ofthe scanner information from the azimuth pulse, aredone bymethods similar tothose ofFigs. 17.2 and 17.5. The upper-beam video signals and thebeacon video signals areseparated bya video switch which consists essentially ofapair ofout-of-phase switches similar tothat made upbytubes V1~and VlbinFig. 
 BEAM TUBES THAT ARE NORMALLY OPERATED AS AMPLIFIERS  THE MAGNETRON  IS AN OSCILLATOR !S EXAMPLE OF A COMMONLY USED EARLY MAGNETRON WAS THE *  AN , 
 IfR.=Zo,itcan beshown easily that allthe energy stored inthe transmission line isdissipated inthe load. Again, from elementary theory, Z,=~L/C =-; 6=lm=m0, where 1isthelength oftheline, Land Citsinductance and capacity per unit length, Lo=lLthetotal inductance oftheline, and Co=lCitstotal capacity. The energy stored isgiven by w=+Cov:, but Ontheother hand, theenergy dissipated intheload isgiven by v; ‘0=FL‘0’or,since v.=: and R==20, w,=~goto=w; therefore alltheenergy stored inthe line isdissipated intheload. 
 THE PROPAGATION FACTOR, FP, IN THE RADAR EQUATION  26.196x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 AREPS considers range- and azimuth angle–dependent atmospheric refractivity  data derived from the upper-air observations of radiosondes, other sensors, or meso - scale meteorological models such as the U.S. Navy Coupled Ocean/Atmosphere  Mesoscale Prediction System (COAMPS).26 Radiosonde data may be manually  entered or automatically decoded from either the World Meteorological Organization  (WMO) observational message format or a free-form column format, obtained from  a number of different data sources. In addition, climatological refractive condi - tions may be selected from a 921 WMO station, worldwide reporting database. 
 TIES 4HIS CHARACTERISTIC REDUCES THE EFFECTIVE BANDWIDTH  TENDING TO BALANCE OUT THE CHANGE SO THAT WITHIN CERTAIN BOUNDS THE RESOLUTION IS APPROXIMATELY INDEPENDENT OF LOSS WITHIN THE PROPAGATING MATERIAL&)'52%  4WO RESOLVED 2ICKER WAVELETS                   &)'52%  4WO UNRESOLVED 2ICKER WAVELETS                . 
 ,0) RADAR DESIGN WITH HIGH !2- RESISTANCE v IN  $'/. TH 2ADAR #ONFERENCE     P   $ ,YNCH  h2EAL TIME RADAR DATA PROCESSING v PRESENTED AT )%%% 3OLID 3TATE #IRCUITS   #OMMITTEE  $IGITAL &ILTERING -EETING  .EW 9ORK  /CTOBER     $ #RAIG AND - (ERSHBERGER  h&,!-2 OPERATOR TARGET/!0 RECOGNITION STUDY v (UGHES !IRCRAFT  2EPORT .O 0 
 Sens. 2002 ,40, 2543–2552. [ CrossRef ] 13. 
 Skolnik (ed.), 1st Ed., New York:  McGraw-Hill, 1970. 72. A. 
 PROPAGATION FACTOR (OWEVER  IF THE CORRELATOR OPERATES IN ITS NONLINEAR REGION  WHICH CAN FREQUENTLY HAPPEN  CROSS 
 For  the standard atmoshphere  € dndh≈−40⋅10−6/km and for the correction factor:   € k≈1,34=4/3 (3.16)  One speaks of a 4/3 Earth radius.  With that the range of coverage is enlarged by approximately  15.7%.  3.4 Bistatic Radar Equation   In the previously derived Radar equation it presupposes that transmitters and receivers  are at the  same place (i.e. 
 When the pulse compression filter is  considered as a matched filter, the output (neglecting noise) is the autocorrelation function of  Antenna  TR  LO Transmitter  IF  amplifier Frequency  modulotor  Pulse  compression  filter  Figure 11.14 Block diagram of an FM pulse compression radar. Video  amplifier To  indicator . i r !Ar  '--(  f?  /1  }1 EXTRACTION OF INFORMATION AND WAVEFORM DESIGN 423  ·-i  fl  i  t,  -,1---,  a I T  (al  /2  (b)  (cl  (d)  _L_~-----Time  Time  Time  l--~~-'-~~~~~~---'-~~~~~~.-Time  t1 t2  ( el Figure l l.15 Linear FM pulse com­ pression. 
 (The increase of a0 with decreasing grazing angle is similar to the  behavior of land clutter but not sea clutter.) The scatterometer, a radar which measures a0 as  a function of incidence angle in the region near vertical incidence, has been used as an ice sensor  and to differen tiate between first-year and multi-year ice.6s  Radar can also detect large icebergs, especially if they have faces that are nearly per-  pendicular to the radar direction of pr~pagation.~~ Icebergs with sloping faces can have a  small echo even though they may be large in size. Growlers, which are small icebergs large  enough to be of danger to ships, are poor radar targets because of their small size and shape.  They seem to be more detectable with radar having a moderate resolution rather than a high  RADAR CLUTTER 481 Figure13.6Composite rough-surface modelofthesea withthesmallresonant waterwavesridingontopofthe largerwaterwaves,resulting inatiltingoftheresonant wavesfromthehorizontal. 
 Improved RMA based on Nonuniform Fast Fourier Transforms (NUFFT’s). In Proceedings of the 2008 9th International Conference on Signal Processing, Beijing, China, 26–29 October 2008; pp. 2489–2492. 
 Inclusion in the first edition would have'been largely academic since the analog  delay-line technology available at that time did not make it practical to build the sophisticated  signal processors that were theoretically possible. However, subsequent advances in digital  technology, originally developed for applications other than radar, have allowed the practical  implementation of the multiple delay-line cancelers and multiple pulse-repetition-frequency  MTI radars indicated by the basic MTI theory.  Automatic detection and tracking, or ADT (Secs. 
 Coherent (doppler) processing provides the necessary processing gain, but the  processing times required—from 1 to 100 s—mean that revisit rates when conducting  surveillance over an extended region will fall below acceptable levels unless multiple  receive beams are processed in parallel. Designers have explored different trade-offs,  in most cases, converging on schemes in which 15–30 receive beams are formed  within a broader transmitted beam footprint. The reduced transmitting antenna gain  may be compensated by increasing power or coherent processing time. 
 First, the authors assessed the precision of SAR-based TEC retrieval by comparing measurements derived from L-band PolSAR data acquired by the ALOS satellite, and from very accurate incoherent scatter radars. Then, the TEC of the topside proﬁle was estimated by subtracting from the TEC derived by PolSAR, the TEC of the bottom side proﬁle measured by an ionosonde observing the same space of the satellite. This procedure allows reﬁning the topside TEC estimations and thus improves the modelling of the electron density topside proﬁle. 
 INTO 
 Because of the constraint of having only five  zeros available, this filter could not provide −46 dB rejection to ±20%. Figure 2.53 b shows the filter that responds to targets as near as possible to zero  doppler, while having a zero-doppler response of −66 dB. Two zeros are placed near  0, providing −66 dB response to clutter at 0. 
 IN METAL  SPHERE TARGET SUPPORTED INSIDE A BALLOON TO MINIMIZE TARGET MOTION ESTIMATED  AT  IN RMS  AN   SERVO BANDWIDTH #OMPONENT "IAS .OISE 2ADAR 
 7  Slant Range ................................ ................................ ................................ 
 Stark, L.: Microwave Theory of Phased-Array Antennas-A Review, Proc. I £EE, vol. 62,  pp. 
 This near match of velocities is what causes the cumulative interac - tion that transfers dc energy from the electron beam to amplify the electromagnetic  wave propagating on the helix. After delivering its energy to the RF field, the spent  electrons are removed by the collector, usually a multistage depressed collector. An  axial magnetic field keeps the electron beam from dispersing as it travels down the  tube, just as in the klystron. 
 For example, if the outputs of 100 ADCs were combined  to form a beam, assuming that each ADC induces noise that is of equal amplitude  and uncorrelated with the others, there would be a 20 dB increase in system dynamic  range, compared to a single-receiver system using the same ADC. Figure 25.22 shows a block diagram of a typical digital beamforming system. Each  antenna output port, be it from an element or a subarray, is followed by a digital  FIGURE 25. 
 Satcllitc-borne radars have also been used for remote sensing as meritioried  below.  Rer~rote Setrsirrg. A11 radars are remote sensors; however, as this term is used it implies the  sensing of geophysical objects, or the "environment." For some time, radar has been used  as a remote sensor of the weather. 
 VELOCITIES FOR THE TARGETS OF INTEREST &OR  CASES WHERE THERE ARE ONLY A FEW AMBIGUITIES IN DOPPLER  DOPPLER CORRELATION MAY BE PERFORMED PRIOR TO OR IN CONJUNCTION WITH RANGE CORRELATION TO MINIMIZE GHOSTING (IGH 
  AND 6 
 SYNTHESIZED SOURCES NOW  MAKES IT ATTRACTIVE TO COLLECT WIDEBAND 2#3 DATA  WHICH CONTAIN FAR MORE TARGET 
 Vincent: Radar-Tracking Accuracy increased, Elcclronrcs, vol 37, pp 73 75,  May 4, 1964.  40. Bean, B. 
 Alternatively, the problem might besolved byphase-locking thecarrier oscillator tothetransmitted pulse trigger, thereby insuring aconstant relative phase between each echo and the carrier. Oscillator isolation would still benecessary, since otherwise astrong moving target might destroy the phase coherence. The Two-channel Amplifier.-The signal level atthe input terminals ofthetwo-channel amplifier must begreat enough sothat the statistical noise generated therein isconsiderably smaller than the statistical noise 1vol.20.. 
 J of "Radar Handbook," M, L Skolnik (ed.). McUraw-llill  Uook Company, New York. 1970. 
 Figure 14.1 Geometry of the synthetic aperture radar  traveling with a velocity o. The radar transmits a pulse at  each position marked by an x. .fp= pulse repetition  frequency. 
 The Rayleigh density function is  Tliis is plottetf iri Fig. 2.2~. Tlie parameter .u might represent a voltage, and (.u2),, the mean, or  average, valirc of tlic voltage squar-ed. 
 AROUND TRACKING   WHICH AVOIDS TRANSMITTING AT THE TIME THAT AN  ECHO IS EXPECTED TO ARRIVE AND CAN RESOLVE THE RANGE AMBIGUITY 4HIS ALLOWS THE RADAR TO OPERATE AT HIGH 02& AND TRACK UNAMBIGUOUSLY TO LONG RANGES WHERE SEVERAL PULSES MAY BE PROPAGATING IN SPACE TO AND FROM THE TARGET 4HE TECHNIQUE IS USEFUL ONLY WHEN A TARGET IS BEING TRACKED $URING ACQUISITION  THE RADAR MUST LOOK AT THE REGION BETWEEN TRANSMITTER PULSES  AND UPON INITIAL ACQUISITION  IT CLOSES THE RANGE 
 DOPPLER  ELEMENTAL 
 UTED AMONG MANY FIXED ELEMENTS OF A PLANAR TWO 
 2007 ,10, 26–38. [ CrossRef ] 3. Yang, X.H.; Zheng, Y.R.; Ghasr, T.; Donnell Kn, M. 
 2013 ,32, 419–432. 46. Guan, S.; Tao, L.; Xie, J.; Xia, D. 
 The total cycle count  is a discrete- number since the. counter is unable to measure fractions of a cycle. The  discreteness of the frequency measurement gives rise to an error called the fixed t:rror, or !itt:p  error. 
 FREQUENCY 5(&  RADARS  THIS EFFECT IS NEGLIGIBLE  AND COMPENSATION IS NOT REQUIRED &)'52%  /PTIMIZED $0#! PHASE COMPENSATION. Î°ÓÓ  2!$!2 (!.$"//+  7HEN IT IS NECESSARY TO COMPENSATE FOR THIS EFFECT  THE PHASE CENTER OF THE ANTENNA  MUST BE DISPLACED AHEAD OF THE APERTURE AND BEHIND THE APERTURE FOR ALTERNATE RECEIVE  PULSES SO THAT THE PHASE CENTERS ARE COINCIDENT FOR A MOVING PLATFORM 4HIS TECHNIQUE CAN BE EXTENDED TO MORE THAN TWO PULSES BY USING THE NECESSARY  PHASE 
 /,1 Ê " /,"  4HE INCREASING DEMAND FOR ELECTROMAGNETIC SPECTRUM FOR BOTH CIVILIAN AND MILITARY  APPLICATIONS HAS ACCENTUATED THE NEED TO CONTROL THE SPECTRUM OF RADAR TRANSMITTERS  TO AVOID INTERFERENCE WITH USERS OF THE ELECTROMAGNETIC SPECTRUM OPERATING AT OTHER FREQUENCIES 4HE ASPECTS OF CONCERN HERE ARE THOSE THAT AFFECT 2& TUBE SELECTION AND ACHIEVEMENT OF MINIMUM SPECTRUM OCCUPANCY BY THE TRANSMITTERS DISCUSSED PREVIOUSLY IN THIS CHAPTER 2EDUCTION OF 3PURIOUS /UTPUTS  2& TUBE SPURIOUS OUTPUTS MAY BE GROUPED INTO  THREE KINDS HARMONICS  ADJACENT 
 Pierson, W. A., et al.: The Effect of Coupling on Monostatic-Bistatic Equivalence, Proc. IEEE, pp. 
 Phys ., vol. 45, pp. 833–850, 1984. 
 Third, we can keep both aerial and reflector fixed, and  obtain the necessary beam-shift by electrical means.  This method is useful where one needs to scan only a  small sector, and techniques have been worked out for  electrical scanning by such methods as phase-shifting.  The alternation of effective angle of the beam is small,  but the scheme is useful where for operational reasons  we must have a very rapid rate of scan, and it would be  physically impossible to rotate or vibrate the aerial array  itself at such a speed. 
 (6) TEC To pis the TEC of the topside proﬁle of the ionosonde. When we can measure the TEC through other equipment precisely, TEC To pis simply obtained by subtracting TEC Bott=/integraltexthmF2 0Nedh from TEC. Substituting Equation (6) into the left side of Equation (4) gives 0.66 Nemax TEC To p (NmF2)2=/integraldisplayHs hmF2e1−z−e−zdh. 
 and 5r = (1.4c)/(2irfl) (21.45) Ambiguities. It is the objective of this subsection to make some observations regarding the possibility of multiple peaks (ambiguities) in the ambiguity function as given by Eq. (21.37) and its effect on system performance as given by Eq. 
 Because oftheavailability ofaverification pulse,the powertransmitted bythenormalsearch-pulse canbelessthanifthedetection decision hadto bemadeonthebasisofonlyasipgleobservation. Thereisalwaysalimittotheinformation thatcanheprocessed byanygeneral-purpose radarcontrolcomputer. Theprocessofinitiating andmaintaining trackcanheverydemand- Table8.1Waveforms usedinAN/FPS-85 satellite surveillance radar I1M 5.Cohcrent extended 40-pulse burstof125- rangetrack /ISpulses;burstdur- ationI s O.Cohcrent intermedi- 40-pulse burstof25-/'ls atedoppler pulses;burstdura- tion0.2s 7.Cohcrent precision 40-pulse burstof5-/ls range pulses,steppedfre- quency;burstdura- tion1.2ms 8.Arraycalibration 60/ls waveformNamc I.Searchchirppulse 1Searchsimplepulse l.Trackchirppulse 4.TracksimplepulseDescription 250Jls,FM 10/IS 250/IS,FM IpsPrimary function Long-range searchand trackacquisition Short-range searchand trackacquisition Long-range track Short-range trackand short-range SLBM search Extended-range lrack andsignature Intermediate doppler andsignature Precision-range tracking Transmitter andre­ ceivermodulecali­ bration. 
 The latter were often more convenient when ﬂying from RAF Chivenor (situated on the north coast of Devon) to operations in the Bay of Biscay, as Lundy Island was too close. For more formal CCDU analysis of sensitivity [ 2] with trials undertaken from RAF Angle (near Pembroke in south west Wales), GrassholmAirborne Maritime Surveillance Radar, Volume 1 7-2. Island was used. 
 The tracking has been described as "wild" and can be great enough to cause the radar  to break track. The effect is most pronounced over a smooth water surface where the reflected  signal is strong. The effect can be so great that it can become impossible to track ta·rgets at low  elevation angles with a conventional tracking radar. 
 134 INTRODUCTION TO RADAR SYSTEMS  chaff, however, as well as sea echo, can have a nonzero mean velocity4 7 which must be  properly accounted for when designing MTI signal processors.  The frequency dependence of the clutter spectrum as given by Eqs. (4.25) and (4.26)  cannot be extended over too great a frequency range since account is not taken of any  variation in radar cross section of the individual scatterers as a function of frequency. 
 Thevariousbeampositions canbeobtained bysampling theoutputatthepropertime.In Fig.8.29onebeamsampling channel isillustrated. Thesampling signalSaisatrainofshort pulsesatarepetition rateiswhichcanbetime-phased togatethescanning signal61:according tothedesiredbeamdirection. Thebeam-steering phaseisindicated byexinthefigure.Ifais variable. 
 Staprans et al.2,18 state that the high-power V A-812C  EIK operated over a frequency range from 400 to 450 MHz (12% bandwidth), with a  peak power of 8 MW and an average power of 30 kW, and an efficiency of 40%. EIK devices have been of interest for millimeter-wave applications. According to  the Communications & Power Industries (CPI) brochure, its VKB 2475 millimeter- wave EIK when operating at a center frequency of 94.5 GHz with a 1 GHz bandwidth,  has a peak power of 1.2 kW, average power of 150 W, about 10% duty cycle, gain  of 47 dB, pulse width of 20 µs, and is liquid cooled. 
 12.7. The primary istuned toresonate with the capacity inthe plate cir- cuit, the secondary with the capacity inthe grid circuit. The coupling. 
 Transmitting antenna module. The radiating elements are stacked microstrip patch antennas with vertical polarization, properly designed by IDS’ laboratories in order to have 1 GHz bandwidth with a VSWR < 1.5 an da3d B beamwidth of 80◦in the azimuth plane and 60◦in the elevation plane. The total gain of the module including the power ampliﬁer gain and transmission line losses is 15.7 dB. 
 At these heights there can  appear at times patches of high-density ionization called sporadic E which, when available,  can be quite effective in providing stable propagation. The multiple refracting regions give rise  to multipath propagation which can result in degraded performance because of the simulta­ neous arrival of radar energy at the target via more than one propagation path, each with  different time delays. The effects of multipath can be reduced by the proper selection of  frequency and by use of narrow elevation beamwidths which allow the energy to travel to the  target via only a single path. 
 System Implementation. Active seekers have used both conical scan and monopulse angle tracking, and the receivers have evolved from the conventional to the inverse configuration, just as with the semiactive. Because of the limitation on achievable antenna size as well as transmitter power, the range performance of an active seeker will be considerably less than for a comparable size of semiactive seeker operating with a high-power large- antenna illuminator.5 Thus active systems are used in short-range homing-all-the- way applications or as the terminal guidance mode of a multimode long-range system. 
 640 MOVING TARGET INDICATION [SEC. 16.5 Sofarwehave assumed that thecoherent oscillator isexactly intune with thei-fecho signals. Ifthis isnotso,thevideo signals arenolonger square pulses but contain anumber ofcycles ofthe beat frequency, as shown inFig. 
 It consists of a rapid circular scan  (conical scan) about the axis of the antenna, combined with a linear movement of the axis of  rotation. When the axis of rotation is held stationary. the Palmer scan reduces to the corrical  TRACKING RADAR177 (al Time-- torIy gateLofe gate Time -~ (r)Earlygate signal L.ategafe signalTime-+Fi~ure5.17Split-range-gate tracking. 
 PULSE  WHOSE SHAPE CONVERGES ON THE FLAT 
 2.6 IMPROVEMENT FACTOR CALCULATIONS Using Barton’s approach,17 the maximum improvement factor I against zero-mean  clutter with a gaussian-shaped spectrum for different implementations of the finite- impulse-response binomial-weight MTI canceler (see Section 2.8) is  Ifr f12 22≈  πσ (2.23)  Ifr f24 22≈  πσ (2.24)  Ifr f364 3 2≈  πσ (2.25) where I1 is the MTI improvement factor for the single-delay coherent canceler; I2 is the  MTI improvement factor for the dual-delay coherent canceler; I3 is the MTI improve - ment factor for the triple-delay coherent canceler; sf is the rms frequency spread of  the gaussian clutter power spectrum, in hertz; and fr is the radar repetition frequency,  in hertz. When the values of sf for scanning modulation in Eq. 2.15 are substituted in  the above equations for I, the limitation on I due to scanning is  In 12 1 39≈. 
 D. L. Lucas and G. 
 The key  factors or specifications that typically drive the design or procurement of the gimbal  are scan rate, slew requirements, acceleration/deceleration requirements, torque and  load (reflector mass) requirements, power requirements, etc. It is important for the  radar system engineer to understand these factors and associated practical gimbal  design limits. Environmental Factors and Considerations. 
 In Fig. 7.17 the feeds are shown on a straight line, but in the parabolic torus they would  lie on the arc of a circle.  The many feed horns plus all the transmission lines of the organ-pipe scanner result in a  relatively large structure with significant aperture blocking. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 18.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 statistical independence requirement evaluated for the TOPEX indicates that the maxi - mum PRF should be 2.5 kHz, yet it was 4.5 kHz in practice. 
 TRACKING TECHNIQUES ALSO OFFERING MOST OF THESE ADVANTAGES ARE USED  NTH 
 J. R.: Microwave Plasma Beam Sweeping Array, IRE Trans, vol. AP-10, pp. 
 This is applicable to coaxial lines or similar structures which propagate the TEM mode.  If the beam is to point in a direction 00, the phase difference between elements should be  2rr(d/).) sin 00. In a frequency-scan array it is usually necessary to add an integral numbe_!:_~  2rr radians of relative phase difference. 
 COMPARISON MONOPULSE SIMUL 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.876x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 It is seen from Figure 2.92 that the velocity response characteristic of the clutter  map from stopband to passband is somewhat gradual in this particular implementation. 
 Lucero was not designed to work on any American variety of centimetric equipment, although equivalentsystems were developed by the Americans. Lucero Mk I was developed to interrogate beacons and IFF Mk III on 176 Mc/s, so that existing coastal beacons could be used. Provision for operation with the BeamApproach Beacon System (BABS) was made by enabling the receiver only to be switched to 173.5 Mc/s, the frequency of the ASV/BA beacons. 
 The linear  FM signal has a phase that varies as t2 (t = time), and the cross-range signal has a phase that  varies as x2 (x = distance along the ground track). Just as the phase history -)fthe cross-range  signal records on film as a Fresnel zone-plate, which then has a focusing action when iHu­ minatcd hy coherent light, so does the signal of the linear FM waveform also record as a  Fresnel zone-plate. The range and the cross-range recorded signals may be treated as orthog­ onal aspects of a single two-dimensional filtering operation. 
 DOPPLER BIN CAN  BE MATCH FILTERED USING THE HYPOTHESIZED MOTION FOR EACH SCATTERER AND AN IMAGE CAN BE FORMED ON THE SHIP %ACH RANGE BIN MAY CONTAIN MULTIPLE SCATTERERS FROM THE SHIP IN A GIVEN ROLL PLANE  AND THEY MAY BE DISTINGUISHED BY THEIR DIFFERING PHASE HISTORY (OWEVER  SCATTERERS IN THE PITCH AXIS AT THE SAME RANGE AND ROLL HEIGHT CANNOT BE SEPA 
 pp. 367-371. May, 1967. 
 QUENCY 02&  AND AT A FIXED RADAR FREQUENCY 4HIS SET OF PULSES IS USUALLY REFERRED TO AS THE  COHERENT PROCESSING INTERVAL #0)  OR  PULSE BATCH 3OMETIMES ONE OR TWO  ADDITIONAL FILL PULSES ARE ADDED TO THE #0) IN ORDER TO SUPPRESS RANGE 
 Pulse cornpressiotl can be used to  cornpensate for the reduced peak power, but at tile price of additional complexity. At the  Iiiglicr frc~luencics tlie backscatter from rain is greater, and tlle MTI blind speeds are more ofa  ~xohleni. IJecause of the smaller apertures and tlie greater effect of rain clutter, S-band radars  arc likely to have less range capability than radars at lower frequencies. 
 J. Richards (ed.), Van Nostrand Reinhold Co., New York, 1969.  69. 
 15.18. There would be little sensible effect on the more constant  vertical returns. Finally, the polarization differences themselves have been shown to  derive entirely from the behavior of the reflection coefficients at the underlying surface  (see, for example, Wright6 and Wetzel12), and so are not an intrinsic part of the Bragg  hypothesis and would apply to any small perturbation on the surface. 
 A.. and I. S. 
 Equipment Group, August, 1976.  57. Skolnik, M. 
 Booker, H. G.: Elements of Radio Meteorology: How Weather and Climate Cause Unorthodox  Radar Vision beyond the Geometrical Horizon. J. 
 S. Candidas, and M. I. 
 Noelectronic beam­ steering isemployed. Thisisaneconomical approach toair-surveillance radarsatthe lowerradarfrequencies, suchasVHF.Itisalsoemployed athigherfrequencies whena preciseaperture illumination isrequired, astoobtainextremely lowsidelobes. Atthe lowerfrequencies, thearraymightbeacollection ofdipolesorYagis,andatthehigher frequencies thearraymightconsistofslottedwaveguides. 
 The  peak errors are severe and can be many times the angular separation between the target and its  Antenna beam ____------- -- - Radar __---- -- -- - ,Direct path ,  _------  --- --- 7 - - - - _ _--_-_ '--%-.3 lmoge  Surface - reflected path  Figure 5.15 Low-angle tracking illustrating the surface-reflected signal path and the target image.  172INTRODUCTION TORADARSYSTEMS changing frequency canresultinamplitude fluctuations whichcanaffecttheangktracking accuracy ifthespectrum -ofthefluctuations attheconicalscanorthelobingfrequencies is increased. Thus,frequency agilitymightcauseanincrease intheanglcerrorduetoamplitude lluctuations inthesesystems whiledecreasing theerrorduetoglint.Theoveralleffectof frequency agilityinconicalscanorsequential lobingsystems istherefore morecomplicated to analyzethanmonopulse systems whichareunaffected byamplitude fluctuations. 
 In this chapter some aspects of  the problem of detecting radar signals in the presence of noise will be considered. Noise  ultimately limits the capability of any radar. The problem of extracting information from the  received waveform is described in the next chapter. 
 P. C. Marth, J. 
 40.Craig.S.E..W.Fishbein. andO.E.Rittenback: Continuous-Wave RadarwithHighRangeResolu­ tionandUnambiguous Velocity Determination. IRETrans.,vol.MIL-6,pp.153-161, April,1962. 
 GAIN ANTENNAS  0LANAR NEAR 
 Mcl~itics: 011 tlic Specification of;tti Antenna Pattcrn Torn Syritlictic Apcrtirrc  Radar. I~rrc~r~rt~rio~~~~l C'oir/c~rc,rrt.c, R:lDAK-77, pp. 39 I 395. 
 ANALOG CONVERTER $!#  &IGURE  DEMONSTRATES HOW AN .#/ OPERATES TO PRODUCE A SINE WAVE 4HE  N 
 SWITCH MODULATOR  THE hHARD 
 Typical values of C are 65 to 75 dB for the  operational weather radars. It is clear that for fixed range and received power, a lower  value of the radar constant C allows a smaller reflectivity value in dB Z to be observed.  Thus, smaller values of C correspond to more sensitive radars. 
 GAIN BEAMS TOWARD DISTANT RECEIVERS AND TRANSMITTERS #OMPLETE FLEXIBILITY IS POSSIBLE SEARCH AND TRACK RATES MAY BE ADJUSTED TO BEST MEET PARTICULAR SITUATIONS  ALL WITHIN THE LIMITATIONS SET BY THE TOTAL USE OF TIME #HAPTER     0ORTIONS OF THIS CHAPTER THAT APPEARED IN EARLIER EDITIONS OF THE  2ADAR (ANDBOOK WERE WRITTEN BY THE LATE  4HEODORE # #HESTON  A PIONEER IN PHASED ARRAY ANTENNAS. £Î°Ó  2!$!2 (!.$"//+  4HE ANTENNA BEAMWIDTH MAY BE CHANGED TO SEARCH SOME AREAS MORE RAPIDLY WITH LESS  GAIN &REQUENCY AGILITY IS POSSIBLE WITH THE FREQUENCY OF TRANSMISSION CHANGING AT WILL FROM PULSE TO PULSE OR  WITH CODING  WITHIN A PULSE 6ERY HIGH POWERS MAY BE GENER 
 Thus the net loss of aircraft-echo power:on changing from linear to circular polarization is  about 2.5 dB. In some cases, however, a.greater value of radar cross section may be obtained  with circular polarization rather, than with linear.79  An alternative to circular polarization is to transmit any linear polarization and receive  on the orthogonal linear polari~ation.'~.~' Spherical raindrops will give no retiirn in the  orthogonal channel if no cross-polarization distortion takes place in the radar or the propaga-  tion medium. There is some evidence to indicate that crossed linear polarization may give  better rain rejection than conventional circular polarization. 
 WORLD ENVIRONMENT IN WHICH THEY MUST OPERATE 4HE 2ADAR %QUATION IN *AMMING AND #HAFF #ONDITIONS  !N EXAMPLE OF RADAR  RANGE PERFORMANCE UNDER NOISE JAMMING IS REPORTED ON PP n OF &ARINA   WHERE  THE IMPORTANT ROLE PLAYED BY A RADAR WITH LOW SIDELOBE ANTENNAS IS ALSO NOTED 4ODAY THE USE OF COMPUTER PROGRAMS FOR PREDICTING RADAR PERFORMANCE UNDER JAMMING  CLUT 
 AES-18, no. 4, pp. 731–736, November 1982. 
 9.5 was one of the  earliest duplexer configurations employed. It consists of a TR (transmit-receive) switch and an  ATR (anti-transmit receive) switch, both of which are gas-discharge tubes. When the transmit-  ter is turned on, the TR and the ATR tubes ionize; that is, they break down, or fire. 
 21.Mathur, P:N.,andE.A.Mueller: RadarBack-scattering CrossSections forNonspherical Targets, IRETrailS.,vol.AP-4,pp.51-53,January, 1956. 22.Scharfman, H.:Scattering fromDielectric CoatedSpheres intheRegionoftheFirstResonance, J. I1rr/.Pl,ys.,vol.25,pp.1352--1356. 
 The heavy horizontal line indicates 1OX2. (Courtesy of University of Michigan Radiation Laboratory.8) TABLE 11.1 RCS Approximations for Simple Scattering Features NOTES: 1. LOS = line of sight. 
 71. Gunn, K. L. 
 The former is usually called directivity, while the latter is often called gain. It is important that the distinction between the two be clearly understood. Directivity (directive gain) is defined as the maximum radiation intensity (watts per steradian) relative to the average intensity, that is, _ maximum radiation intensity _ maximum power per steradian D average radiation intensity total power radiatedMir This can also be expressed in terms of the maximum radiated-power density (watts per square meter) at a far-field distance R relative to the average density at that same distance: _ maximum power density _ pmax D ~ total power radiated/4-ir R2 ~ P/4ir R2 Thus the definition of directivity is simply how much stronger the actual maxi- mum power density is than it would be if the radiated power were distributed isotropically. 
 The Doppler frequency  is  similarly subdivided into frequency regions.  A block diagram of the entire arrangement is  shown in Figure 8.13.  IF Amplifier Range Gate 2 Range Gate mFilter 1 Filter 2Filter 2Filter 2 Filter nFilter n Filter 1Detector 2 Detector n Detector 2Detector 2 Detector n Detector 1Detector 1Range Gate 1 Filter 1 Detector 1    Figure 8.13  Range gates and Doppler filter arrays. 
 vol.9,no.3,pp.364-380, 1952;alsoreprinted inProc.Symposium onCommullicatioll Theoryalid Antenna Design,AFCRC Tech.Rept.57-105, ASTIADocument 117067,January, 1957. 100.Bracewell, R.N.:Tolerance TheoryofLargeAntennas, IRETrailS.,vol.AP-9,pp.49-58,1anuary, 1961. IOI.Ruze,1.:Antenna Tolerance Theory-A Review, Proc.IEEE,vol.54,pp.633-640, April,1966. 
 The major differences in sea clutter for the two polarizations are seen to lie in the range of grazing angles be- tween about 5 and 60°, where the horizontally polarized returns are smaller. This difference is found to be emphasized at both lower wind speeds and lower fre- quencies. The cross sections approach each other at high angles (>50°) and, for the higher microwave frequencies, at low angles (<5°) as well. 
 SEARCH)  INPHASE)&  INTERMEDIATE FREQUENCY).3  INERTIAL NAVIGATION SYSTEM)00  INTERPULSE PERIOD,.!  LOW 
 COBRA.  The COunter Battery RAdar (COBRA) C-Band solid -state phased  array radar (see Figure 13.42) locates rocket launchers, artillery batteries, mortars,  shell impact points, and jamming directions. The antenna, which is mechanically  trained, has 2720 radiating elements, each fed by a solid state T/R module to provide  wide electronic scan coverage. 
 3.3. The Cassegrain receiving antenna is on the right. Both antennas  have a "tunnel" around the periphery for further shielding. 
 When p = 180°, the forward-scatter case, fB - O for any 5. Equation (25.17) shows that: • For a given 8, the magnitude of the bistatic target doppler is never greater than that of the monostatic target doppler when the monostatic radar is located on the bistatic bisector. • For all p, when -90° < 8< +90°, the bistatic doppler is positive; under this definition a closing target referenced to the bistatic bisector generates a posi- tive, or up9 doppler. 
 (More ;-\recisely, ~t determines the direction of the waves driven by the wind since  the wave and wind djrections are not exactly coincident.) Note that In Eq. (14.23) the doppler  534lNTRODUCTlON TORADAR SYSTEMS 0----ARW 10--------+---+------/-- II.J o} \ ./2./3 2RRW --_.- --I---H-----+----~ --++--U--+--+H-l 40 50_.4i ~20a. 4l.2 ~30 a:: Figure14.8Spectrllm llfIheradarechofromthe,eaobtained fromanareaabout9.5by7.5kmvia groundwave propag;.tion. 
 BAND DATA ILLUSTRATED PREVIOUSLY IN &IGURE  A B CAN ALSO  BE SHOWN TO CORROBORATE THE PREDICTIONS OF THIS MODEL FOR A SIMILAR WIND SPEED AND GRAZING ANGLE  THUS FURTHER SUPPORTING THE SUSPICION THAT BREAKING 
 It may  be considered as the degradation of the signal-to-noise ratio caused hy the network (receiver),  or it may be interpreted as the ratio of the actual available output noise power to the noise  power which would be available if the network merely amplified the thermal noise. The  noise figure may also be written ·  ~To BnG + l!:.N = l + l!:.N  kToBnG kToBnG (9.2)  where l!:.N is the additional noise introduced by the network itself.  The noise figure is commonly expressed in decibels, that is, JO log F n. 
 (c) Bulk Carrier image with rotate. 304. Sensors 2019 ,19,6 3 These three datasets were trained with models as shown in Section 2.1. 
 MODULATED CONTINUOUS 
    
 92 INTRODUCTION TO RADAR SYSTEMS  techniques can be similar. Pseudorandom phase-coded waveforms40 and random noise  waveforms41•42 may also be applied to CW transmission. When the modulation period is long,  it may be desirable to utilize correlation detection instead of matched filter detection. 
 With automation, r eproducibility of  test results can be maintained regardless of production  personnel changes  and training requirements can  be  significantly reduced.   Signal Monitoring   Signal monitoring  is a different challenge. For Signal  Monitoring, t here is less need to verify a specification, but  more to identify si gnals that may be present in the surrounding  area or show t hemselves only very rarely. 
 TO 
 /\1.:TI<lIlsil'nl Response ofTracking FilterswithRandomly Interrupted Data.IEEE III/liS.vol/\1:S-6.pp.313323.May.1970. XI.Morgan. ()R.:ATargetTrajectory NoiseModelforKalman Trackers. 
 ,  In practice, long-range MTI radars that operate in the region of L or S band or higher and  are primarily designed for the detection of aircraft must usually operate with ambiguous  doppler and blind speeds if they are to operate with unambiguous range. The presence of hl~nd  speeds within the doppler-frequency band reduces the detection capabilities of the radar. Blind  speeds can sometimes be traded for ambiguous range, so that in systems applications which  require good MTI performance, the first blind speed might be placed outside the range of  expected doppler frequencies if ambiguous range can be tolerated. 
 Finitebandwidths resultinfiniterisetimesandfinitefJ2. Inordertocompute f12(andtherangeerror)forapractical" rectangular" pulse,itwillbe assumed thatthepulsespectrum isoftheformSU)=(sinnfr)/nf,justaswiththeperfectly rectangular pulseofwidthr,butthatthebandwidth islimitedtoafinitevalueBasshownin Fig.[1.4.(,Thisisequivalent topassing aperfectly rectangular pulsethrough afilterofwidth B.Thetimewaveform oftheoutputwillbeapulseofwidthapproximately t,buttheslopesof theleadingandtrailing edgesarefinite.Anexample oftheshapeofabandwidth-limited rectangular pulseisshowninFig.11.5.Theintegrals intheexpression for{32[Eq.11.16] extend, inthisinstance, from-B/2to+B/2insteadoffrom-00to+00.Thustheeffective handwidth is R/2 (2rrrrf2(sin2rrfr)/rr2f2tlfnBr-sinnBrf12= ~/-i8/!- ------------- =----------- ----".--,--- rt25i(nBt)+(cosnBr-1)/nBr (sin2rrfr)/n2f2tlf • -R/2 whereSixfsthesineintegral function defined byr(sinu)/uduoAsBr~00,theproduct • 0 22Bf1:::::--- rforlargeBr (11.19) t a. E <[--B----------~ rrnn1lnnr'J __-.Figure11.4Spectrum ofaband­ width-limited "rectangular pulse.". 
 VAPOR IN THE ATMOSPHERE ARE VARI 
 Heating is more dangerous in the brain, the testes, the hollow  iscera, and the eyes, where there is little opportunity for the exchange of heat with the  urrounding tissue.  Many instances have been reported where cataracts have been deliberately formed in the  eyes of animals by exposure to microwave radiation. The viscous material of the eyeball is  PROPAGATION OFRADAR WAVES465 200 '"3150--o L- '"0- E '" l1J100-- Vl oc Figure12.13Computed antenna noise-temperature asa function ofelevation anglefora10-ft-diameter (3m) parabolic-reflector antenna operating atafrequency of 1GHz.(AfterGreene,61 courtesy Airborne lllstrllmellts Laboratory. 
 21, Verlag Leemann, Zurich, 1955.  29. Luck, D. 
 LOG ;    =.   4HIS IS TABULATED IN 4ABLE   4HIS DISCUSSION OF !$ QUANTIZATION NOISE HAS ASSUMED PERFECT !$ CONVERTERS  -ANY !$ CONVERTERS  PARTICULARLY UNDER HIGH 
 . Radar System Engineering  Chapter 7 – CW and FM -CW Radar  42     Figure 7.1  Block circuit diagram of a simple CW Radar.     The mixture on an IF Band in MHz range gives some relie f, since the NF noise of the sem i- conductors approximately decreases by 1/f. 
 46 RCS Reduction Methods • Shaping (tilt surfaces, align edges, no corner reflectors) • Materials (apply radar absorbing layers)• Cancellation (introduce secondary scatterers to cancel the “bare” target) From Fuhs. 47AN/TPQ-37 Firefinder • Locates mortars, artillery, ro cket launchers and missiles  • Locates 10 weapons simultaneously  • Locates targets on first round  • Adjusts friendly fire   • Interfaces with tactical fire • Predicts impact of hostile projectiles • Maximum range: 50 km  • Effective range:  Artillery: 30 km, Rockets: 50 km • Azimuth sector: 90° • Frequency: S-band, 15 frequencies • Transmitted power: 120 kW• Permanent storage for 99 targets; field exercise mode; digital data  interface . 48SCR-270 Air Search Radar  . 
 The decor­ relation times at 95 GHz varied from about 3.4 ms at 5 mm/h rain rate to 1.4 ms at 100 mm/h.  At X band the decorrelation times were longer and varied from 14 ms at 5 mm/h to 5.4 ms at  100 mm/h.  Utility of millimeter waves. 
 All of this  complex motion shows up in a doppler shift imparted to the scattered electromagnetic  wave. Unfortunately, there is as yet little detailed physical understanding of the com - plicated phenomenology of sea clutter spectra. Measurements of microwave clutter spectra for real seas have been reported in the  literature for aircraft measurements of the spectral shape alone,58,59 fixed-site shore  measurements showing a shift in the spectral peak,60,61 and measurements from ships  at intermediate grazing angles.45 Other measurements of sea clutter spectra include  those made at much lower frequencies in the HF band, as described in the last section;  those made under artificial conditions in wave tanks,62 whose application to real-sea  conditions is uncertain; and those from other fixed-sites at high resolution and short  averaging times, to be discussed later. 
 46. DiLorenzo, J. V.: GaAs FET Development-Low Noise and High Power, Microwave J., vol. 
  
 OMNIDIRECTIONAL PATTERN IS FORMED FOR SIDELOBE DETECTION BLANKING AS DISCUSSED IN 3ECTION  2ECEIVER0ROTECTOR 20   4HE RECEIVERPROTECTOR IS A LOW 
 Modulation methods include varying the PRF, either continuously or in discrete steps; varying the RF carrier, with either linear or sinusoidal FM; or some form of pulse modulation such as pulse-width modulation (PWM), pulse-position modulation (PPM), or pulse-amplitude modulation (PAM). Of these modulation techniques, PWM and PPM may have large errors because of clipping of the received modulation by eclipsing or straddling (discussed in Sec. 17.7), and PAM is difficult to mechanize in both the transmitter and the receiver. 
 ERATIVE TRANSMITTERS )N THE NONCOOPERATIVE TRANSMITTER COLUMN  IF A NONCOOPERATIVE TRANSMITTER AND A  HITCHHIKER WERE LOCATED IN OR NEAR A BATTLE AREA  A HITCHHIKER COULD USE THAT TRANSMITTER IN THE CO 
 For such cases Eqs. (2)and (3)would bemodified bysubstituting thetransmitted and received values ofthe energies per pulse forthe respective pulse- power values. Itissensible todesign the system sothat R;NR:since there isno useinhaving replies that aretoo weak tobeobserved even though the beacon isbeing interrogated, ascan bethe case ifR:<R?.Likewise nothing isgained bymaking provision forstrong replies ifthey areabsent because ofthe failure ofthe interrogation. 
 TO 
 Ionospheric tomography by combining vertical and oblique sounding data with TEC retrieved from a tri-band beacon. J. Geophys. 
 19.47. The exponential form of the drop-size distri - bution generally fits the average of several drop-size distributions that occur over dif - ferent phases of convective and tropical rainfall and are averaged over space or time.  However, the “gamma” drop-size distribution represents a better fit to instantaneous,  natural variations of the drop-size distribution under different conditions. 
 Houts. R. C., and D. 
 The output generates the pulsed radio frequency (RF) transmit  signal, which is the transmit drive signal that is amplified by the power amplifier prior  to being fed to the transmit antenna. Antenna.  The antenna can be mechanically or electronically scanned. 
 3.13 where Kisanumerical constant which canbeinterpreted asthereflection coefficient ofthe ground. Equation (32) isbased onthe assumption that every bitofthe incident energy that isheaded foranarea onthe ground will strike some object inthat area, where afraction, (1–K), will beabsorbed, and afraction, K,will bereradiated, alldirections of reradiation being assumed equally probable. Some experimental N FIG. 
 Kaplan: Bistatic Surface Clutter Resolution Area at Small Grazing Angles, MITRE Corporation, RADC-TR-82-289,ADA\2366Q, Bedford, Mass., November 1982. 88. Moyer, L. 
 ERED -OST TARGETS GIVE RETURNS THAT VARY MORE RAPIDLY OVER PART OF THE INCIDENCE 
 Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar.  PULSE COMPRESSION RADAR  8.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 performance in terms of SNR loss and peak time sidelobe level (TSL) than the LFM  waveform. The TSL level does not degrade appreciably for the LFM waveform for  higher radial velocities, demonstrating the higher doppler tolerance of LFM.FIGURE   8. 
 Beckmann and A. Spizzichino, The Scattering of Electromagnetic Waves from Rough Surfaces ,  New York: Macmillan Company, 1963. 59. 
 CAST THUS  THE BROADCAST TRANSMITTER MODULATION GOES TO ZERO AND RANGE MEASUREMENT ERRORS INCREASE WITHOUT LIMIT 4HIS CONDITION CAN OCCUR WHEN BROADCASTING A TALK SHOW OR CLASSICAL MUSIC  BUT OCCURS LESS OFTEN WITH POPULAR OR ROCK MUSIC  4HE FREQUENCY  OF THIS TYPE OF OUTAGE IS NOT INSIGNIFICANT  OCCURRING ROUGHLY ONCE PER SECOND FOR TALK BROADCASTS  #ONSEQUENTLY  ONCE A TRACK HAS BEEN ESTABLISHED A NONLINEAR TRACKING FILTER  MAY BE NEEDED TO EDIT OUT LARGE ERROR SPIKES SEE #HAPTER  OF 7ILLIS AND 'RIFFITHS  2ADIO &REQUENCY )NTERFERENCE  0ASSIVE BISTATIC RADAR PERFORMANCE IS SUBJECT TO  DEGRADATION BY RADIO FREQUENCY INTERFERENCE 2&)  FROM BOTH THE EXPLOITED BROADCAST TRANSMITTER AND OTHER EMITTERS IN SPATIAL OR FREQUENCY PROXIMITY 4HESE EMITTERS CAN INCLUDE BROADCAST  COMMUNICATIONS  AND NAVIGATION TRANSMITTERS  AS WELL AS POWER TOOLS  FLUORESCENT LIGHTS  COOLING FANS  AND OLD  AUTOMOBILE I GNITIONS  WHICH TYPICALLY  GENERATE IMPULSIVE NOISE   2&) CAN ARRIVE VIA A DIRECT PATH OR MULTIPATH AND INCLUDES  SCATTERING FROM TERRAIN OR SEA SURFACES  ALSO CALLED CLUTTER (OWEVER  THE SIGNAL FROM AN EXPLOITED TRANSMITTER ARRIVING OVER THE DIRECT TRANSMITTER 
 LAR 
 Thus the choice of  T1 /T2 is a compromise between the value of the first blind speed and the depth of the nulls  within the filter pass band. The depth of'the nuJ1s can be reduced and the first bJind speed  increased by operating with more than two interpulse periods. Figure 4.17 shows the response  of a five-pulse stagger (rour periods) that might be used with a long-range air traffic control  radar. 
 The average  inlprnvement for all filters is indicated by t lie dotted curve. (From ~t~drews.~~)  MTIi\NDPULSE DOPPLER RADAR125 o L 0001~ ~60----- ! >o D. E-~rTr!-----r II I ~ I Ii 01I 0.01II I 5 I 4,6l---ave. 
 of the doppler filter-bank. The fast Fourier tra~lsform algorittl~n 1s ilsed to in~plenlcnt the  doppler filter-bank. Since the first two pulses of a three-pulse canceler are n~eaningless, only  the last eight of the ten pulses output from the canceler are passed to the filter-bank. 
 The letter G is used for equipment capable of being used in two or more different types of ground installations. Equipment specifically designed to operate while being car- ried by a person is designated by the installation letter P. The letter U implies use in a combination of two or more general installation classes, such as ground, air- craft, and ship. 
 150INTRODucnON TORADAR SYSTEMS 47.Nathanson, F.E.:"Radar DesignPrinciples," McGraw-Hili BookCo.,NewYork,1969. 48.Goldstein, H.:TheEffectofClutterFluctuations onMTl,MJTRadiacion Lab.Repc.700,Dec.27, 1945. 49.Barlow, E.J.:Doppler Radar,Proc.IRE,vol.37,pp.340-355, April,1949. 
 Skolnik (ed.),McGraw-Hili BookCo.,NewYork,1970. 34.Rheinstein, J.:Backscatter fromSpheres: AShortPulseView,IEEETrans.,vol.AP-16,pp.89-97, January, 1968. 35.Miller,E.K.,G.1.Burke,B.J.Maxum. 
 Geosci. Remote Sens , vol. 32, pp. 
 -1, 
 Hine: Servomechanisms, chap. 11 of" Mechanical Engineering in Radar and  Communications," C. J. 
  
 orbinary integrator, wasoriginally employed inradarasanautomatic integrator, hutithasother properties ofinterest. Theoptimum number m(orthesecondthreshold) willdependonthe natureofthepdf.Whentheoptimum misusedwithnon-Rayleigh-clutter. them-ollt-of-II detector seemstobebetterthantheotherreceivercriteria.l,ut! Thelogarithmic receiver hasanoutputvoltagewhoseamplitude isproportional tothe logarithm oftheinputenvelope. 
 D. White, “Techniques for tracking low-altitude radar targets in the presence of multipath,”  IEEE Trans ., vol. AES-10, pp. 
 On the ground, the con - stant-range contours are the intersections of concentric spheres with the ground—a set  of concentric circles with the subradar point at the center (Figure 17.4 b). The contours  of constant LOS velocity (called isodops ) correspond to the intersections between the  set of cones and the flat ground—a set of nested hyperbolas (Figure 17.4 c). Figure 17.4 d  shows the combination of constant-range circles and the isodops . 
 APPROVED RADARS )N PRACTICE  ANTENNAS FOR EXISTING  SHIPBORNE RADARS NORMALLY ROTATE AT n RPM ON HIGH 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 5.44  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 31. 
 14. D. Middleton and H. 
 Substituting Equation (8) into Equation (2), d(rVr)/dr=−αr can be obtained, and the general solution is Vr=−α 2r+c/r. Considering r→0at the vortex core, a ﬁnite velocity is ensured. Therefore, the integral constant cis zero, and Vr=−α 2r (9) By substituting Equation (9) into Equation (6), H(r)can be obtained. 
 4.6 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 which is defined as a collision course. The target aspect angle is zero for a head-on  condition and 180° for a tail chase. The aspect angle corresponding to the boundary  between the sidelobe clutter region and the sidelobe clear region is a function of the  relative radar-target velocity ratio and is shown in Figure 4.4 for four cases. 
 NOISE RATIO  AN   SERVO BANDWIDTH /THER )NTERNAL 3OURCES OF %RROR  4HERE ARE MANY OTHER SOURCES OF INTERNAL ERRORS  THAT ARE SMALL IN WELL 
 310. sensors Article Simulation and Analysis of SAR Images of Oceanic Shear-Wave-Generated Eddies Yuhang Wang1,2,3, Min Yang1,2and Jinsong Chong1,2,* 1National Key Lab of Microwave Imaging Technology, Beijing 100190, China; wangyuhang15@mails.ucas.ac.cn (Y.W.); minyang993@126.com (M.Y.) 2Institute of Electronics, Chinese Academy of Sciences, Beijing 100190, China 3School of Electronics, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 101408, China *Correspondence: iecas_chong@163.com; Tel.: +86-010-5888-7125 Received: 23 February 2019; Accepted: 26 March 2019; Published: 29 March 2019/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: Synthetic Aperture Radar (SAR) is widely used in oceanic eddies research. High-resolution SAR images should be useful in revealing eddy features and investigating the eddy imaging mechanism. 
 centre-zero  type, and are placed in a balancing network so that all  the pilot has to do is set a course on which the milliam-  meter needle shows a centre reading. Deviation from  the true course—that is, head-on to the appropriate  radar beacon—will be shown by corresponding milliam-  meter needle swing. Each. 
   NO   PP n  3EPTEMBER . °£/À>V}Ê,>`>À  i>Ê °ÊÜ>À` #ONSULTANT TO )44 )NDUSTRIES  )NC °£Ê  /," 1 /"  4YPICAL TRACKING RADARS HAVE A PENCIL BEAM TO RECEIVE ECHOES FROM A SINGLE TARGET AND  TRACK THE TARGET IN ANGLE  RANGE  ANDOR DOPPLER )TS RESOLUTION CELLDEFINED BY ITS ANTENNA BEAMWIDTH  TRANSMITTER PULSE LENGTH EFFECTIVE PULSE LENGTH MAY BE SHORTER WITH PULSE COMPRESSION   ANDOR DOPPLER BANDWIDTHIS USUALLY SMALL COMPARED WITH THAT OF A SEARCH RADAR AND IS USED TO EXCLUDE UNDESIRED ECHOES OR SIGNALS FROM OTHER TARGETS  CLUTTER  AND COUNTERMEASURES %LECTRONIC BEAM 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 It should be noted that for a rectangular array a different illumination may be  chosen for each plane. This is appropriate if the sidelobe requirements in each of  the planes are different. 
   42!#+).' 2!$!2   °£x RATE OF ROTATION 4HE  3   $ AND 3 n $ OUTPUTS EACH LOOK LIKE THE OUTPUT OF A CONICAL 
 The frequency response’s symmetry about 1/4 of the  sampling rate causes the even-and odd-numbered coefficients to be purely real and  purely imaginary, respectively, so the even-and odd-numbered coefficients are used  to, respectively, create I and Q, as shown in Figure 25.16 b and c. After the filters, the complex signal is decimated by 2 to produce a 50 MHz output  sample rate. The final spectral convolution by a –75 MHz tone is accomplished by  negating every other sample. 
 Oceanic  Technol ., vol. 11, pp. 1184–1206, 1994. 
 The advantage of the modulating anode is that it requires little control  power to modulate the beam. The power necessary is that required lo charge and discharge the  capacitance of the klystron gun and its associated circuitry, and this is independent of the pulse  length. The cutoff characteristics of the modulating anode permit only a few electrons to  escape from the electron gun during the interpulse period when the beam is turned off. 
 2.Both systems arerelatively simple, and design problems encoun- tered intheir development are more basic innature and more generally applicable than inthe case ofamore elaborate system, where usually alarge proportion ofthe system isvery specialized innature. 3.These two systems represent opposite extremes inrequirements. Limitations onfactors such assize, \veight, and power requirements fortheground-based setwere largely subordinated totherequire- ment forthe best possible radar performance. 
 RAE installed a common T & R using an antenna coupling box type 9, and removed the transmit antenna, which solved the problem. Antenna coupling box type 9 wassimilar to the type 8, but used for common T & R from the broadside arrays of ASV Mk. II, such as on the Liberator III, ARI 5184 (see section 2.2.2.2 ). 
  
 Shelton, J. P., and K. S. 
 Moore The University of Kansas (CHAPTER 16) Andy Norris Consultant in Navigation Systems (CHAPTER 22) Wayne L. Patterson Space and Naval Warfare Systems Center (CHAPTER 26) Keith Raney The Johns Hopkins University Applied Physics Laboratory (CHAPTER 18) John D. Richards The Johns Hopkins University Applied Physics Laboratory (CHAPTER 13) Robert J. 
 MENT FACTOR THAT CAN BE OBTAINED WITH A MAGNETRON IS NOT AS GOOD AS CAN BE OBTAINED WITH A LINEAR 
 For further study, we also compared our method with other popular models. • Traditional CNN models The ﬁrst model we used is traditional CNN models, as shown in Figure 1a. These models consist of four convolution layers, four max pooling layers and two fully connected layers. 
 Choice offrequency depends upon the’ delay-line attenuation, and on thefact that thenumber ofcarrier cycles perpulse must besufficient to allow accurate demodulation. Itwas mentioned earlier that the quartz-mercury combination has adequate inherent bandwidth. Inareflecting end cell the response is actually flat over afrequency range equal to40per cent ofthe carrier frequency. 
                      
 OF 
 Diode phase shifters have been built in practically all transmission line media, including  waveguide, coax and stripline. Microstrip is useful for medium-power devices because of the  ease of manufacture, circuit reproducibility and its reduced size, weight, and production costs.  The diode chips may be mounted directly on the substrate without the parasitic reactances of  the diode packages. 
 The echo signal reradiated by the target arrives back at the radar via the same two  paths. Thus the received echo is composed of two components traveling separate paths. The  magnitude of the resultant echo signal will depend upon the amplitudes and rlative phase  difference between the direct and the surface-reflected signals. 
 1025. Asthe phenomenon ofmode-changing isbecoming better understood, improvements which alleviate the troubles are being incorporated into both magnetrons and pulsers. The radar designer should become fully familiar with the requirements that amagnetron places onpulse shape and pulser impedance. 
 J.: Wirid Torques or, Rotating Radar Aerials, Mut.corri Reu., VOI. 28, pp. 147-l70,2d qtr.. 
 Hardy, T. G. Konrad, W. 
 Special attention had to be paid to theelectrical screening in the aircraft, par ticularly the engine ignition, to prevent interference with the radar. Theﬁrst Hudson installation was quite experimental. The wavelength was still a nominal 1.5 m, as it had been for the pre-war work on RDF 2, and used a frequency of 214 Mc/s. 
 E. Nathanson, J. P. 
  &)'52%   !XIAL VIEW OF  TRIPOD STRUT BLOCKAGE INTERFERENCE  PATTERNS   
 With the above system parameters, a receiver system that will provide  the maximum obtainable performance is shown in Figure 2.82. At the output of the  pulse-compression network, the system instability noise will be equal to or less than  thermal noise for either distributed clutter or point clutter, and the peak clutter signals  will vary from about 28 dB above thermal noise for evenly distributed clutter to 58 dB  above thermal noise for strong point clutter. Because the MTI canceler is expected to attenuate clutter by 30 dB, the second lim - iter is provided to prevent the residue from strong clutter from exceeding the threshold. 
 This  illustrates why most radars operating at microwave or UHF frequencies are limited to cover­ age within the geometrical line of sight.  12.7 ATTENUATION BY ATMOSPHERIC GASES5•12·28  The attenuation of radar energy in a clear atmosphere in the absence of precipitation is due to  the presence of oxygen and water vapor. Attenuation results when a portion of the energy  incident on the molecules of these atmospheric gases is absorbed as heat and is lost. 
 Effects of phase shifter quantizatior~.R2.1 '" The discrete value of phase shift that results from  tlie use of qua~itized phase shifters introduces an "error" in the desired aperture illumination.  Phase quantization can cause a loss in antenna gain, an increase in the rms sidelobe level, the  generation of spurious sidelobes, and a shift in the pointing of the main beam. The effect of  quantized phase shifters on the radiation pattern is similar to the effect of random errors. 
 Its design is based  upon the fact that, over limited angular regions, a spherical surface viewed from any  point halfway between the center of a sphere and its surface is nearly parabolic. This  means that if a feed is moved along an inner spherical surface of constant radius R/2,  where R is the radius of the spherical reflector, the secondary beam can be steered. The  range of beam steering is limited by the size of the spherical reflector, i.e., the portion  of a full sphere realized by the reflector. 
 2002 ) Ward Model Urban (1 Site;  179 km2) Mountains (1 Site;  58 km2) Rural (Aggregate of 5 Sites; Various Terrain Types; 2,087 km2) Receiv er Saturation RCS (m2)10010−410−310−210−1100101102103104 101102103104105Number of cells per km2 with RCS > Abscissa ch02.indd   19 12/20/07   1:43:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 If we are using centimetric waves we can make  our reflector so small (as the aerial may be a rod only a  few inches in length) that it is a parabolic mirror focusing  the energy into a beam. Even longer-wave trans-  missions can be similarly beamed, using reflectors made  of wire-mesh or similar light-weight material. If itis not  practical to use such reflectors and directors we can use  a number of aerials, suitably placed and phased to con-  _centrate energy in one direction. 
 In the last edition of this Handbook (1990), the final statement in this chapter was  “It will be interesting to see what progress will have been made in the theory of sea  clutter by the publication of the next edition of this handbook.” It appears that the  answer is—not much. But there is some evidence that the theory of sea scatter is  gradually being freed from the paralyzing monotheism of Bragg scatter, so there is  hope for the future. REFERENCES  1. 
 Transmitter pulse shapes and spectra generally deviate significantly from gaussian. 6 dB Definitions. Although antenna beamwidths (and number of echoes re- ceived) are often specified between the 3 dB points, this actually represents a 6 dB definition of the echo response as the radar antenna scans past the target; in those radars whose transmitting and receiving beams are not identical, the 6 dB points of the two-way pattern are usually specified. 
 The reference waveform applied to the LO port of the CM has  LFM slope equal to BR/TR = B/T.  The instantaneous frequency at the correlation mixer output is the difference  between the instantaneous frequencies at the CM input and LO ports. As a result, the  CM output signals for the three target signals are uncoded pulses (pulsed CW signals)  with frequency offset from the mixer IF output fIF given by   δfB Ttd = −   (8.24) FIGURE   8. 
 Geosci. Remote Sens. 2011 ,49, 3730–3736. 
 -ÊÊ   Ê/ 
 Knight, The Handbook of Antenna Design , V ol. 2,  London: Peter Peregrinus, Ltd., 1983. 10. 
 POLARIZATION MAPPING MODES  A 3CAN3!2 MODE  A VARIETY OF DUAL 
 VATION OF THE %ARTHS OCEANS AND LARGER SURFACE WATER BODIES   PLANETARY RADARS WHERE hPLANETv INCLUDES PLANETOIDS SUCH AS LARGE MOONS   SCATTEROMETERS WHOSE DATA ASSOCI 
 TO 
 TO 
 The density modulated electrons  thus form bunches, and RF energy is extracted by passing the beam through the  resonant cavity. The CEA has been widely used for UHF-TV transmitters, a highly  competitive industry concerned with cost. It has been said that in UHF-TV, the use  of a CEA reduces the required prime power by one-half compared to a conventional  tube transmitter45 and by one-third of the prime power of a silicon-carbide solid- state transmitter.46 The CEA achieves these efficiencies since there is no loss of effi - ciency when using shaped pulse waveforms, as there is with other microwave tubes. 
 INv PULSE MUST ALSO BE TRANSMITTED AND PROCESSED 4O PREVENT POINTS OF STRONG CLUT 
 606-612, September, 1971.  59. Baars, J. 
 1.  31. Craig, C. 
 Am., vol. 22, pp. 78-82, March 1984. 
 SIDERATION 5NDER STANDARD OR NORMAL ATMOSPHERIC CONDITIONS  THE RADIO RAY CURVES DOWNWARD WITH A CURVATURE LESS THAN THE %ARTHS SURFACE 4HE EFFECTIVE 
 (28) istobreak upthe original radiation pattern ofthe source atAinto alo’be structure, as sketched inFig. 2.11; atleast this isanappropriate description ofthe effect ataconsiderable distance from thesource. The lowest maximum inFig. 
 GAUSSIAN  BEHAVIOR MAY BE ACCOMMODATED BY ONE OF THE MULTIPARAMETER OR COMPOUND DISTRIBU 
 A change in the power input voltage, phase, or frequency is identified by the addition of the let- ters X, Y, or Z to the basic nomenclature. When the designation is followed by a dash, the letter T, and a number, the equipment is designed for training. The let- ter V in parentheses added to the designation indicates variable systems (those whose functions may be varied through the addition or deletion of sets, groups, units, or combinations thereof). 
 Union, 24th Annual Meeting, pp. 452-460, 1943. 25. 
 For a particular system of mixed units, the following equation is obtained from Eq. (2.10): P - 1?0 ?[/>/(kW)TM<sfi^r^/2^r211/4 r? -n *--129'2[ /MHz2W,L J (2J1) The subscript notation Rm&x is now meant to imply the range corresponding to specified detection and false-alarm probabilities. For this equation, the range is given in international nautical miles. 
 SCALE DISPLACEMENT SUCH AS THE SUBSIDENCE OF URBAN AREAS OR THE SWELLING OF VOLCANOES PRIOR TO THEIR ERUPTION  #ANADAS REQUIREMENT TO MAINTAIN NEAR 
 This technique finds itsgreat- est utility inthe vertical plane where vertical stretching isused toenhance theaccuracy ofaircraft height determination (see discus- sion ofRHI, Sec. 6.6). Rectangular Presentation of Range and Angle.—A plane sur- face isoften represented inade- formed manner by combining range and angle incartesian rather than inpolar coordinates. 
 T.: Radar Response to Vegetation, IEEE Trans., vol. AP-23, pp. 36-45, January, 1975. 
 "ELLO  , $ATASHVILI  ( "AIER  - - 1UINTINO DA  3ILVE  AND 7 0ARADELLA  h4HE -!03!2 MISSION /BJECTIVES  DESIGN  AND STATUS v IN  0ROCEEDINGS  OF %53!2  $RESDEN  'ERMANY  )4' 6$%    ( +IMURA AND . )TOH  h!,/3 0!,3!2 4HE *APANESE SECOND 
 10.8. (Sirnilar resi~lts are available for fluctuating  target^.^^*^*.^^) This curve  is approximate sirlce there is some slight dependence upon the false-alarm probability, but it  appears to be irldeperldent of the signal-to-noise ratio. The actual value of rtt can diner  sig~~ific.;~~~tiy frot~l ttr,,,, witl~otrt a large penalty in signal-to-noise ratio. 
 Met,raw-Hill BookCompany, NewYork,1951. 29.Ringwalt. D.L..andF.C.Macdonald: Elevated DuctPropagation intheTradewinds, IRETrailS., vol.AP-9,pp.377-383, July,1961. 
 BASED  AIRBORNE  AND SPACEBORNE PLATFORMS -ASS  6OLUME  3TOWAGE  $EPLOYMENT  AND 'IMBALING  4HE DEGREE TO WHICH  THESE FIVE FACTORS   MASS  VOLUME  STOW AGE  DEPLOYMENT  AND GIMBALING DRIVE THE REFLEC 
 Mack: On Measuring the Radar Cross Sections of Ducks and Chickens,  Proc. IEEE. vol. 
 TIME CORRECTIONS TO THE TARGET COORDINATES  TRACKING ACCURACY WILL BE SEVERELY IMPAIRED 4O ADDRESS THESE VARIOUS NEEDS  IT IS ADVANTAGEOUS TO ADOPT CORRESPONDING DESCRIP 
 It is obtained by recording the round trip travel time of a pulse, TR,  and computing range from: where  c= 3x108m/s is the velocity of light in free space. TIME TRAMPLITUDETRANSMITTED  PULSE RECEIVED   PULSEBistatic:  tr RRR c T+ = Monostatic:  ( )2RtrcTR RRR = ==. 8Classification by Function Radars Civilian Military Weather Avoidance Navagation & Tracking Search & Surveillance Space Flight SoundingHigh Resolution  Imaging & Mapping Proximity Fuzes Countermeasures. 
 TION  THE SIGNAL IS SHIFTED TO AN INTERMEDIATE FREQUENCY )&  BY MIXING WITH A LOCAL 
 19, 1908.  92. flor~gl~tori. 
 This implies the continued use of short pulse radars.  However, for the 2008 standards, IMO has encouraged improvements in sea clut - ter performance by dropping the need for racon compatibility at 3 GHz, thereby  allowing other forms of modulation that would enable affordable coherent pro - cessing techniques. Because all ships above 300 gt need to carry at least a single  9 GHz radar, it means that racon (and SART) detection capability is maintained. 
 , vol. 71, pp. 2929–2943,  1966. 
 RADAR TRANSMITTERS 217  technology. Although there liave been significant advances in microwave solid-state devices  and altliougli they possess properties that differ from other microwave sources, the degree of  application of these devices to radar syste~ns has been limited.  h.licrowave transist~r.~~~~.~~ At L band tlie CW power that can be obtained from a single  microwave transistor might be several tens of watts. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.46  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 have been shown to support spatially coherent processing.113,114 Hence, the receiving  array apertures of skywave radars may range from ~ 0.3 km for systems concerned  only with aircraft and ballistic missiles to more than 4 km in systems designed for ship  detection and tracking. 
 Figure 11“31shows theinterior detail ofoneofthese compartments; intheother, theitems arethesame but aremounted the other end up. The pulse from themodulator comes inthrough thepulse connector onthe end ofthe case. For the long-range search setthe power from themodulator isabout 2Mw, orabout 10kvonthe50-ohm cable. 
 The  time sidelobes accompanying the compressed pulse are objectionable since they can mask  desired targets or create false targets. When limiting is employed, there can be small-target  suppression and possibly spurious false-targets as well. The long uncornpressed pulse can  restrict the minimum range and the ability to detect close-in targets. 
 The  power gain and the directive gain may be related by the radiation efficiency factor p, as follows:  G = ~,GD (7.7)  The radiation efficiency is also the ratio of the total power radiated by the antenna to the net  power accepted by the antenna at its terminals. The difference between the total power  radiated and the net power accepted is the power dissipated within the antenna. The radiation  efficiency is an inherent property of an antenna and is not dependent on such factors as  impedance or polarization match. 
 Since it is not always possible to know the exact nature of the errors that might be  encountered in a specific antenna, the properties of the antenna must be described in statistical  terms. That is, the average, or expected, value of the radiation pattern of an ensemble of  antennas of similar type can be computed based on the statistics of the random errors. The  statistical description of the antenna properties cannot be applied to any particular antenna,  but applies to the collection of similar antennas whose errors are specified by the same  statistical parameters. 
 6. Palma-Vittorelli, M. M., M. 
 L., and R. N. Bracewell: "Radio Astronomy," Oxford University Press, London, 1955. 
 DEGREES DEGREES (c) W FIG. 6.2 Various representations of the same sin xlx pattern. POLAR-RELATIVE AMPLITUDERELATIVE POWER RELATIVEAMPLITUDEDECIBELS RELATIVE TO PEAK DEGREES (b) (a) . 
 Burns, and W. P. Clark: Phase Shifters lor Arrays, chap. 
 LIKE COMPONENT OF THE SIDELOBES IS DOWN  D" FROM THE  PEAK TRANSMITTED SIGNALS 4HIS NOISE 
 Atlas, “Precipitation motion by pulse doppler radar,” in 9th Weather  Radar Conf ., AMS, Boston, 1961, pp. 218–223. 147. 
 In this case the signal operations required have the form ZSnWn = unfocused synthetic pattern (21.63) There are many mechanizations possible to carry out the operations indicated by Eqs. (21.62) and (21.63). Some of them are described below. 
 CM DEPTH SHOWN  MUCH OF THE SCATTER AT  AND  '(Z IS PROBABLY FROM THE UNDERLYING SURFACE 3OME REPORTS STATE THAT THERE ARE  RADAR HOT SPOTS IN SNOW COVER  PARTICULARLY AT   '(Z 4HESE REPORTS RESULT FROM IMPROPER INTERPRETATION OF VARIATIONS THAT ARE DUE TO NORMAL 2AYLEIGH FADING OF THE SIGNAL 3CATTER FROM SNOW COMES FROM MANY CEN 
 LOSS INTERCONNECTIONS BETWEEN THE AMPLIFIER MODULES AND THE COMBINER 0OWER COMBINERS MAY BE EITHER ISOLATIVE OR REACTIVE DESIGNS )N ISOLATIVE DESIGNS   ANY IMBALANCE OR DIFFERENCE BETWEEN THE PHASE AND AMPLITUDE OF THE VOLTAGES THAT ARE BEING COMBINED IS DIRECTED TO A RESISTIVE TERMINATION 4HE  NET RESULT IS THAT A CON 
 P. Royan, “Seek Igloo radar clutter study,” Rome Air  Development Center, Report No. Rept. 
 Finally, the work in [ 10] proposes improving the interferometric near-ﬁeld 3D imaging by using a multichannel joint sparse reconstruction. The basic idea consists in deriving multichannel signals by dividing the two observed full apertures into sub-apertures. Then, by exploiting the sparsity of the target echo in each channel, the imaging problem is set up as a multichannel joint sparse reconstruction, and the 3D target image of each sub-aperture target is obtained through the improved orthogonalmatching pursuit method. 
 POINT CONNECTION S )N ORDER TO COMMUNI 
 The ionospheric models that have been extensively used in . HF radar performance analysis are in programs called ITSA-I, ITS-78, RADAR C, IONCAP, and AMBCOM.43^7 Lucas48 provides some detail on these models and their origins. In summary, they all draw on the large database of recorded ionospheric soundings made during the International Geophysical Year of 1957-1958 and the International Year of the Quiet Sun of 1964-1965. 
 A. Woroncow. and B. 
 TION -OREOVER  THERE IS RELATIVELY LITTLE GOOD DATA ON VERY LOW 
 J. Miller, “Minimizing the effects of phase quantization errors in an electronically scanned  array,” in Proc. Symp. 
   
 It is also possible to derive velocity from multiple measurements scanning over a  target, but this works well only in relatively uncluttered situations where the media has  no anisotropic characteristics. Dispersion.  The frequency dependent nature of the dielectric properties of the mate - rial causes the phase velocity of the component frequencies of a wideband signal to suffer  differential propagation values. 
 WATER MEASUREMENTS FAR LESS ACCURATE 4HIS VELOCITY MEASUREMENT PROVIDES IN 
 HORIZON RADAR THAT EXTENDED THE RANGE OF DETECTION  OF AIRCRAFT AND SHIPS  BY AN ORDER OF MAGNITUDE L $IGITAL PROCESSING  WHICH HAS HAD A VERY MAJOR EFFECT ON IMPROVING RADAR CAPABILI 
 ING WORD IS ADDED TO THE OUTPUT OF A RUNNING SUM  IMPLEMENTED AS AN ADDER FOLLOWED BY A REGISTER 2%'  4HIS PRODUCES A UNIFORMLY INCREASING PHASE  INCREMENTED AT THE SYSTEM CLOCK RATE 4HE  M -3"S OF THE RUNNING SUM ARE SENT TO A PHASE 
 # OPERATION IS THE PREFERRED MODE BECAUSE THE 2& OUTPUT POWER OF THE AMPLIFIER IS MAXIMIZED FOR A GIVEN PRIME POWER INPUT )N GENERAL  THE BASE 
 The last tube isacathode follower which supplies negative video. SEC. 12.10] LIGHTH”EIGIIT AIRBOR.YE RECEIVER 467 signals atl-volt peak, through a75-ohm line, tothe video amplifiers at thecathode-ray tubes. 
 Slater, Near-field Antenna Measurements , Norwood, MA: Artech House, 1991. 111. H. 
 We shall, therefore, consider thereceiver asbeginning atthepoint where thesignal channel branches from that which isshared with thetransmitter. R-fsignals from theantenna byway oftheTR switch enter acrystal mixer where they are combined with the c-w output ofatuned local oscillator toform aheterodyned signal atthe desired intermediate fre- quency, usually 30to60IUc/sec. This signal isledfrom themixer into anintermediate-frequency amplifier ofvery special characteristics, where 1Ifthenormalizations areequal thedisplay is,ofcourse, equivalent toCategory a. 
 When the power in the cells drops to the noise  level, those cells behind it are declared blind. Since penetration range into a storm is  not great, the MFAR weather mode usually has provisions to mark the last visible or  reliable range on the weather display. This is so the pilot does not fly into a dark area  believing there is no weather. 
 Cohen, E. D.: Trapalis and lmpatts: Current Status and Future Impact on Military Systems, IEEE  EASCVN'75, pp. 130-A to 130-G. 
 Theaverage savingsalsodependuponwhether detection isperformed coherently or noncoherently. Assuming coherent detection (pulsesintegrated predetection) andPv=0.90 andPra=10-8,theSequential Observer isabletodetermine, ontheaverage, thatnoisealone ispresentwithlessthanone-tenth thenumber ofobservations required fortheNeyman­ Pearson Observer.9oInthepresence ofathreshold signal,theSequential Observer requires, ontheaverage, aboutone-half thenumber ofobservations oftheequivalent fixed-sample observer. Againassuming Pv=0.90andPra=10-8,anoncoherent Sequential Observer (pulsesintegrated postdetection) requires onlyone-fourteenth thenumber ofobservations whenonlynoiseispresent. 
 IEEE, vol. 73, pp. 182-197, February 1985. 
 15.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 Numerical Methods.  With rapid increases in computer speed, it has become  practical to solve certain scattering problems by numerical methods, thereby side - stepping the introduction of the approximations required by the analytical solutions  described above. In surface scattering, particularly for the continuous sea surface, the  method of choice appears to be some variant of the Method of Moments.117 An exact  integral equation for the surface currents  excited by an illuminating field is solved  numerically over a grid of points, where the flexibility and accuracy of the solution  depends, essentially, on the grid spacing, the size of the surface features compared to  the illuminating wavelength, the extent of the surface over which the grid is laid, and  the efficiency of the computing algorithms used in what are extensive calculations. 
 The Palmer,  spiral, and raster scans are employed in fire-control tracking radars to assist in the acquisition  of the target when the search sector is of limited extent.  5.8 OTHER TOPICS  Servo system. The automatic tracking of the target coordinates in angle, range, and doppler  frequency is usually accomplished with a so-called Type I I servo system.1.2·3•67•68 It is also  referred to as a zero velocity error system since in theory no steady-state error exists for a  constant velocity input. 
 1970.  26. 'Trunk, (i. 
 48. Sensors 2019 ,19, 2764 Conﬂicts of Interest: The authors declare no conﬂict of interest. References 1. 
 l’reciscly the same law describes the distribution inintensity of thermal noise po!rer asamplified bythe i-famplifier ofthe radar set, and this isone reason forthestriking similarity between rain clutter ancl receiver noise asseen onaradar oscilloscope. There is,however, onc LThis point isdiscussed ingreater detail inChap. i’,Vol. 
 A very wideband series feed with equal path lengths is shown in Figure 13.31 d.  If the bandwidth is already restricted by phase scanning, then very little advan - tage is obtained at the cost of a considerable increase in size and weight. The  network in Figure 13.31 e gives simplicity in programming because each phase  shifter requires the same setting. 
 BASED .,&- WAVEFORM WITH  @       AND AN ,&- WAVEFORM 4HE SENSITIVITY OF A .,&- WAVEFORM TO DOPPLER SHIFT CAN BE SEEN IN &IGURE    WHICH SHOWS THE MATCHED FILTER OUTPUT FOR A SINE 
 Long9pointsoutthat"twoflightsoverapparently thesame typeofterrainmayattimesdifferbyasmuchastodBin0"0."Suchvariation anduncertainty inthevalueoflandcluttermustbeaccounted forbyconservative radardesign. Thedataforlandclutterisusuallyreported intermsof0"0,thecrosssectionperunitarea, justasforseaclutter.However, itissometimes givenbyaparameter ywhichequalsO"°/sintjJ, wheretjJisthegrazing angle.Foridealroughterrain, yisapproximately independent ofthe angletjJ,exceptatlowgrazing anglesandnearperpendicular incidence. Anexample ofclutter 0"0forseveralbroadclassesofterrainisshowninFig.13.8.This appliestoX-bandclutter.Theboundaries ofthevariousregionsarewidetoindicatethewide variation ofthedatawithintheclassesofterrain.Figure13.9illustrates airbornt/data atXand Lbandsobtained bytheNavalResearch Laboratory.3? Theazimuth beamwidth was5°and thepulsewidthwas0.5J.lsateachfrequency. 
 -   2 * 3ERAFIN AND * 7 7ILSON  h/PERATIONAL WEATHER RADAR IN THE 5NITED 3TATES 0ROGRESS AND  OPPORTUNITY v "ULL !M -ETEOROL 3OC  VOL   PP n  !-3  "OSTON     2 * 3ERAFIN  h.EW NOWCASTING OPPORTUNITIES USING MODERN METEOROLOGICAL RADAR v IN  0ROC  -ESOSCALE !NALYSIS &ORECAST 3YMP  %UROPEAN 3PACE !GENCY  0ARIS    PP n   4 $ #RUM AND 2 , !LBERTY  h4HE 732 
  
 TIME 
 Since these boundaries can be detected before any clouds are present and because it is possible to infer the air mass convergence that is taking place along these boundaries through doppler measurements, more precise prediction of thunderstorm occurrence appears to be possible. From the radar designer's standpoint, such applications dictate the use of antennas with very low sidelobes and signal processors with significant ground clutter rejection capability. The NEXRAD radar system, with 50 or more dB of clutter rejection, is well suited to this eventual operational task. 
 B.: Rotating Wave Radar, Electronics, vol. 19, pp. 130-133, July, 1946. 
 77-180. 19. Sanders, B. 
    
 7.Krishnan, S.:DiodePhaseDetectors, Electronic andRadioEngr.,vol.36,pp.45-50,February, 1959. 8.Lawson, J.L.,andG.E.Uhlenbeck (eds.):..Threshold Signals," MITRadiation Laboratory Series, vol.24,McGraw-Hill BookCompany, NewYork,1950. 9.Oliver,B.M.:Automatic VolumeControlasaFeedback Problem, Proc.IRE,vol.36,pr.466473, April,1948.. 
 The altitude ofthetarget, which iscomputed electrically astheproduct ofrange and sine ofelevation angle, isshown directly onameter calibrated infeet. When SM equipment isused onshipboard, angles between the antenna and the structure ofthe ship must beproperly corrected with respect toastable vertical, maintained byagyro, inorder toyield the true angles which would have been measured with respect toalevel structure. Considerable attention has been paid tothe stabilization of radar antennas onships and aircraft, and tothedata correction that can sometimes beused asasubstitute (see Chap. 
 142.Hansen, R.C.(ed.):SpecialIssueonActiveandAdaptive Antennas,lEEE Trans.,vol.AP-12,no.2, March,1964. 143.Skolnik, M.I.,andD. D.King:Self-Phasing Arrays,IEEETraIlS.,vol.AP-12,pp.142-49,March, 1964. 
  HAD  
 Each cavity is a short piece of resonant  slow-wave structure based on ladder geometry. The tube weighs 6.2 kg and can oper - ate over a temperature range from −15 to +60oC. It was predicted that this EIK would  be capable of two years of continuous operation with a 92% confidence level. 
 1959.  17. Crispin, J. 
 Figure 8c was the image obtained using the proposed method. The targets now had low azimuth sidelobes and the mainlobes had not been widened, compared with those in Figure 8a,b (for example, see the target in the red circle). 47. 
 HEIGHT RATIO 2( AND AZIMUTH ANGLE X. Î°È  2!$!2 (!.$"//+  4!##!2 4HE -)4 ,INCOLN ,ABORATORY ORIGINALLY DEVELOPED 4!##!2 TO SOLVE  THE !-4) RADAR PROBLEM 4HE REQUIREMENTS AND THUS THE IMPLEMENTATION OF 4!##!2  CHANGE DEPENDING UPON THE TYPE OF CLUTTER CANCELLATION PROCESSING EMPLOYED !FTER MANY OTHER APPROACHES  IT WAS RECOGNIZED THAT IF ONE USED THE CLUTTER RETURN RATHER THAN THE TRANSMIT PULSE TO PHASE 
 BRIGHT RESPONSE FROM -ERCURYS POLAR CRATERS  FOR EXAMPLE  AS OBSERVED BY %ARTH 
 DIMENSIONAL COMPRESSION RATIO OF THE 3!2 DATA 4HUS  THE DYNAMIC RANGE CAPACITY AFTER PROCESSING FOR -AGELLAN IMAGERY WAS IN EXCESS OF  D" 4HIS WAS WELL ILLUSTRATED IN THE MANY  THOUSANDS OF IMAGE FRAMES FORMED FROM -AGELLANS 3!2 DATA (YBRID 
 24.3 governing the SLC is immediately  recognized. With respect to SLC, adaptive array techniques offer the capability of enhancing  the target signal while canceling the disturbance. The adaptive system allocates in an  optimum fashion its degrees of freedom to the enhancement of the target signal and to  the cancellation of jammer. 
 STATE  4RACK %RROR )N 0OSITION )N 6ELOCITY 2ADAR DETECTION NOISE STANDARD DEVIATION 
 CIES BELOW ( n , (      THE SPURIOUS FREQUENCIES ORIGINATE FROM HIGH 
 140. Skolnik, M. I.: Resolution of Angular Ambiguities in Radar Array Antennas with Widely-Spaced  Elements and Grating Lobes, 1 EEE Trans., vol. 
 The radiation  efficiency is an inherent property of an antenna and is not dependent on such factors as  impedance or polarization match.  The relationship between the gain and the beamwidth of an antenna depends on the  distribution of current across the aperture. For a .. 
 pp. 47 58. October. 
 The first  blind speed is at V/VB = 56.25. ch02.indd   42 12/20/07   1:44:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The rest of this chapter will provide a guide for determining the  significant error sources and their magnitudes. It is important to recognize what the actual radar information output is. For a  mechanically moved antenna, the angle-tracking output is usually obtained from the  shaft position of the elevation and azimuth antenna axes. 
 Library of Congress Cataloging In Publlcatlon Data  Skolnik, Merrill Ivan, date  Introduction to radar systems.  Includes bibliographical references and index.  1. 
 Another useful modification is to separate the beams at zero elevation so that the data from  the vertical and the slant beam do not appear close in time. OTHER RADAR TOPICS 543  Monopulse. An elevation angle measurement can be made similar to that of the monopulse  radar described in Sec. 
 GET !PPROPRIATE TIMING PULSES PROVIDE  RANGE GATING SO THE ANGL E 
 FIELD PATTERN 4HIS WOULD OCCUR BECAUSE THEY WOULD BE SPACED AT A FREE 
 arranges them inproper form tomodulate the. 682 RADAR RELAY [SEC. 172 transmitter. 
  AND " 
 . 132 HOW RADAR WORKS  But many civil air experts believe that it is unnecessary  to go to such lengths to produce a self-contained navi-  gational aid which demands no co-operation from the  ground. Absence of ground organization is essential in  war, but in peace air lines travel over well-known routes,  and can obtain all ground assistance. 
 A scan-to-scan integration imjlrovcmc~~t  can be achieved with the high-speed antenna if the storage properties of the CKT screen permit  efficient integration (as with a storage tube) or if some form of automatic integration is used.  Experimental measurements using civil-marine radar with a lo beamwidth and 5000 Hz  pulse repetition frequency show that increasing the antenna rotation rate from 20 to  420 rpm improves the target-to-clutter ratio from about 4 to 8 dB depending on the sea  state." (The smaller improvement corresponds to the higher sea state.) An attempt was also  484INTRODUCTION TORADAR SYSTEMS function) withshortpulsewidths,asdiscussed inSec.13.3.Thechanges inclutterstatistics mustbeaccounted forinthedetector design,elsethelargesignal-to-c1utter ratiosrequired ofa conventional threshold detector mightnegateanybenefitoftheshortened pulse.Asmentioned previously, aradarwithaveryshortpulse(ornarrowbeamwidth) mightprovetobeworse thanonewithalongerpulse(orawiderbeamwidth) because ofthechange inclutter statistics. (Receiver detection-criteria forcompensating theeffectsofachangeincluttersta­ tisticswithhighresolution arediscussed laterinthissection.) Third,ifthepulseistooshort,it mightencompass onlypartofalargetargetsuchasaship,andthetargetcrosssectionmight bereduced. 
 Watkins: The Plasma Panel as a Potential Solution to the  Bright Labelled Radar Display Problem, International Conference on Displays for Man-Machine  Systems, Apr. 4-7, 1977, IEE (London) Conference Publication no. 150, pp. 
  
 (a) PolSAR Scene of group 1.      (b) PolSAR Scene of group 2.     (c) PolSAR Scene of group 3. 
 Maxwell’s four differential equations constitute a suc - cinct statement of the relationship between electric and magnetic fields produced by  currents and charges and by each other.23 The four equations may be manipulated for  isotropic source-free regions to generate the wave equation:  ∇ + =2 20 F Fk (14.4) where F represents either the vector electric field or the vector magnetic field.  Equation 14.4 is a second-order differential equation that may be solved as a boundary- value problem when the fields on the surface of the scattering obstacle are specified.  The fields are typically represented as the sum of known and unknown components  (incident and scattered fields), and the boundary conditions are the known relation - ships that must be satisfied between the fields (both electric and magnetic) just inside  and just outside the surface of the obstacle. 
 MERIT FOR A DOPPLER PROCESSOR  4O SIMPLIFY THIS CALCULATION THE  AVERAGE SIGNAL 
 SUM EDGETAPER (dB) FIG. 6.20 Conflicting taper requirements for sum and difference horn designs (H plane illustrated). between the goals of high sum-beam efficiency and high difference-beam slopes. 
 Those figures will act as signposts  for other mental calculations.  The early chain warning system of radar stations in Britain used what radar experts now regard as ‘very long’ wavelengths, between 10 and 13 metres. The special Chain Home Low equipment for detecting low- flying aircraft worked on 200 Mcs. 
 51.Tollefson. R.D.:Application ofFrequency Modulation Techniques toDoppler RadarSensors, Natl. CalifProc.Aeronaut. 
 TRARILY MODULATED TRANSMIT WAVEFORMS TO BE MODIFIED PULSE 
 This technique  depends upon the fact that for tumbling hail the differential reflectivity, the ratio of  horizontal to vertical reflectivity, is near unity ( ≈0 dB). This differs sharply from  heavy rain, where this ratio can be as large as 5 dB because large water droplets are  horizontally oriented. The combination of absolute reflectivity factor and the dual  polarization differential reflectivity gives unique signatures for hail and heavy rain,  each of which is characterized by a high reflectivity factor. 
 17.13] 10&MC/SEC F-M EQUIPMENT 721 aninsertion loss ofless than 2dbfrom 290 to320 Me/see, and aloss of more than 40dbabove and below this band. The design isconventional: three T-sections are matched tothe line with air-section ateach end. Inductors areused asseries elements, and combinations oflines asthe shunt elements. 
 Lloyd: A Global Ionospheric Model, Naval Res. Lab. Rept., 8321, Aug. 
 Transponder jammers gener - ally send the same amplitude reply to all signals they receive above a threshold and,  therefore, do not simulate actual target fluctuation responses. In addition, they usually  appear wider in azimuth than real targets owing to the modulation effect of the radar  scanning antenna’s response on the real target. Repeater jammers can be made to simu - late the actual amplitude response of real targets and, hence, are more effective over  transponder-type jammers from an ECM viewpoint. 
 PLANE DATA SHOW GOOD CORRELATION  L !TTEMPTS TO MODEL  R" DATA HAVE BEEN MADE USING GEOMETRICAL  STATISTICAL  AND SEMI 
 LIMITING AMPLIFIER  THE PEAK EXCURSION OF THE PHASE 
 l), the noise figure FL due to the RF losses is simply  FL = LR F (9.14)  350INTRODUCTION TORADAR SYSTEMS Diodeburnout. Acrystaldiodewhichissubjected toexcessive RFpower may sufferbUrtlOlj[. Thisisaratherlooselydefinedtermwhichisappliedtoanyirreversible deterioration inthe detection orconversion properties ofacrystaldiodeastheresultofelectrical overload.If excessive RFenergyisappliedtothediodetheheatgenerated cannotbedissipated properly andthediodecanbedamaged. 
 (1.8) can  be substituted into Eq. (1.7), first for A, then for G, to give two other forms of the radar  equation  These three forms (Eqs. 1.7, 1.9, and 1.10) illustrate the need to be careful in the inter-  pretation of the radar equation. 
 7.22, below). If accurate prediction of the array performance is required, many more elements are needed than are indicated above.49'50 It is often convenient to assume that the array is infinite in extent and has a uniform amplitude distribution and a linear-phase taper from element to element. In this manner every element in the array sees exactly the same environment, and the calculations for any element apply equally to all. 
 See Billingsley17 and other papers by him  for more discussion of the situation for fixed radars observing ground targets. For a  moving radar, this motion of the target changes the relative velocities between target  element and radar so that the spectrum is different from that for a fixed surface. The  width of the spectrum due to vehicle motion determines the ability of the radar to  detect this target motion. 
   PP n    7 ( 3TILES AND & 4 5LABY  h4HE ACTIVE AND PASSIVE MICR OWAVE RESPONSE TO SNOW PARAMETERS   PART ) WETNESS v * 'EOPHYS 2ES  VOL   PP n    & 4 5LABY AND 7 ( 3TILES  h4HE ACTIVE AND PASSIVE MICR OWAVE RESPONSE TO SNOW PARAMETERS   PART )) WATER EQUIVALENT OF DRY SNOW v * 'EOPHYS 2ES  VOL   PP n    ) * "IRRER  % - "RACALANTE  ' * $OME  * 3WEET  AND  ' "ERTHOLD  h3IGNATURE OF THE !MAZON  RAIN FOREST OBTAINED WITH THE 3EASAT SCATTEROMETER v )%%% 4RANS  VOL '% 
 The lower  trace in Figure 10 is a spectrum analyzer detected envelope  of  a single RF pu lse seen in the voltage waveform of  Figure 9.  A spectrum analyzer can also show the frequency spectrum of  the pulse. The sin(x) / x (pronounced "sine x over x ") classic  pulse spectrum plot is seen in the upper trace. 
 269 -308,  April, 1960.  38. Nathanson, F. 
 The result is that the horizontally polarized component is  cancelled to a greater extent than the vertical component so that the original circi~lar polariza-  tion is converted to elliptical polarization with the vertical component pred~minating."~  Assuming a 3.2" vertical beamwidth with cosecant-squared shaping up to 10". theoretical  calculations give the following maximum cancellation ratios as limited by surface rellcctions:  20.2 dB for sea, 23.6 dB for marsh, 27.2 dB for average land, and 34.1 dH for dd~rt.~~ Otller  calculations for ground-mapping radars, such as those used for airport surface-tratfic control,  indicate significantly worse cancellation limitations. A 3" vertical beamwidth, pointed 0.7"  below the horizon, with cosecant-squared shaping up to 30' will result in the cancellat ion ratio  being limited to about 13 dB over water and 17 dB over moist soil." To minimize the  problem, narrow vertical beamwidths should be employed. 
 The minor lobe approximately 180° from the main lobe is called the backlobe. Sidelobes can be a source of problems for a radar system. In the transmit mode they represent wasted radiated power illuminating directions other than the desired main-beam direction, and in the receive mode they permit energy from undesired directions to enter the system. 
 512–520, 1988. 94. R. 
 1Thestory ofradar’s operational useinthewaristold, inaway that issomewhat blurred about theedges bythecensorship obtzining just before theendofthewar with Japan, inapamphlet entitled “Radar: AReport, onScience atWar,” released bytheJoint Board onScientific Information Policy onAug. 15,1945. Itisobtain- able from the Superintendent ofDocuments, U.S. 
 One member of each pair is due to the total surface current  on the diffracting edge (including the assumed filamentary edge currents), and the  other is due to the uniform physical optics currents. Mitzner subtracted one member  of each pair from the other, thereby retaining the contributions from the filamentary  edge currents alone. The results have the identical form of Ufimtsev’s expressions, in which the PO  coefficients are subtracted from the non-PO coefficients. 
 302-310, July 1940. 52. Pratt, W. 
 77 CH 1271-6 AES.  94. Mrstik. 
 Collin and f. l  Zucker (eds.), McGraw-Hill Book Co., New York, 1969.  l 03. 
 The short waveleng'ths allow narrow  beamwidths of high directivity witli pt~ysically small antennas. Narrow beamwidths are impor-  tant for high-resolution imaging radar and to avoid multipath effects when tracking low-  altitude targets. The short wavelengths of millimeter waves are also useful when exploring  scattering objects whose dimensions are comparable to the millimeter wavelengths, such as  insects and cloud particles. 
 RANGE SIGNAL IS   ).. 
 A. L. Barghausen, J. 
 However, for the case  of a linear frequency modulation waveform, the matched filter is generally followed  by a weighting filter to provide a reduction in time sidelobe levels. In this case, the  weighting filter results in a signal-to-noise ratio loss compared to that of matched filter  processing alone.  8.2 PULSE COMPRESSION WAVEFORM TYPES The following sections describe the characteristics of the linear and nonlinear fre - quency modulation waveforms, phase-coded waveforms, and time-frequency coded  waveforms. 
 MTI RADAR  2.976x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 FIGURE  2.96 STC can greatly reduce the number of birds displayed. Range 25 nmi. ( a) Birds seen with  MTI and ( b) birds seen with MTI and STC. 
 ABLE AZIMUTH REGION 4HE TRANSMIT WAVEFORM INCLUDES 4!##!2 MODULATION TO CENTER MAINBEAM CLUTTER  AT ZERO DOPPLER FREQUENCY (OWEVER  BECAUSE THE RADAR IMPLEMENTS ADAPTIVE CLUTTER CANCELLATION 34!0   THE REQUIREMENTS ON 4!##!2 ARE SIGNIFICANTLY LESS COMPLEX THAN FOR LEGACY RADAR SYSTEMS 4HERE IS NO NEED TO INCLUDE CLOSED LOOP ADJUSTMENTS TO THE 4!##!2 MODULATION FREQUENCY 4HE OPTIMIZATION OF THE !-4) CLUTTER CANCELLA 
 Radartutorial (www.radartutorial.eu)   8    Figure 9: Definition of elevation angle     Figure 10: Altitude vs. Height  The True Bearing  (referenced to true north) of a radar target is the angle between true north and a  line pointed directly at the target. This angle is measur ed in the horizontal plane and in a clockwise  direction from true north. 
 Dobson, F. Kouyate, and F. T. 
 The four commonly used controls are: 1.Arange-selector switch that enables theoperator tochoose either acontinuously variable, 4-to25-mile sweep ora50-mile sweep for search operation, oraO-to90-mile or70- to160-mile sweep primarily intended forbeacon operation. Two-mile range marks are provided onsweeps shorter than 14miles, 10-mile marks on. SEC. 
 TechnoL, vol. 3, pp. 400-413, 1986. 
 LINE DISTANCE BETWEEN THE TRANSMITTER AND RECEIVER IS JUST TANGENT TO THE %ARTHS SURFACE &OR A HOMOGENEOUS ATMOSPHERE  THIS POINT OF TANGENCY WITH THE %ARTH IS REFERRED TO AS THE  GEOMETRICAL  HORIZON &OR AN INHOMOGENEOUS ATMOSPHERE USING AN EFFECTIVE EARTH RADIUS  AND AT RADAR AND OPTICAL FREQUENCIES  THIS POINT OF TANGENCY IS REFERRED TO AS THE  RADAR AND  OPTICAL HORIZON  RESPECTIVELY 4HE ABILITY OF THE ELECTROMAGNETIC WAVE TO PROPAGATE BEYOND THE HORIZON BY DIFFRAC 
 The ratio of signal energy to noise energy, denoted EIN0, is a more fundamental parameter than the signal-to-noise (power) ratio in theoretical analyses based on statistical detection theory. No matter what the shape of the received waveform, if the receiver is designed as a matched filter the peak signal-to-noise (power) ratio at the output of the matched filter is 2EIN0. For a rectangular pulse of width T the signal power is Eh and the noise power is N0B9 where E = signal energy, N0 = noise energy, or noise power per unit bandwidth (provided the noise is uniform with frequency), and B - receiver bandwidth. 
 SURFACE HEIGHT SIGNALS OF LESS THAN  ^  KM IN LENGTH 2ATHER THAN ABSOLUTE 33( ACCURACY  THESE SHORTER 
 Kawamoto, H .. H.J. Prager. 
 The appearance oftheA-scope isshown inFig. 16”5, where one moving target t C.w f Power transmitter amplifieri ‘‘f 1’ Pulse I F1m16,4,—Doppler effect with pulsed system suitable for low frequencies. isseen among several stationary ones. 
 The filter configuration must be  more complex, however, than the single, narrow-bandpass filter. A narrowband filter with a  passband designed to pass the doppler frequency components of moving targets will " ring"  when excited by the usual short radar pulse. That is, its passband is much narrower than the  reciprocal of the input pulse width so that the output will be of much greater duration than the  input. 
 SIZE DISTRIBUTIONS THAT OCCUR OVER DIF 
 Symmetrical targets, such as  spheres or pipes, cause migration of the reflected energy to a hyperbolic pattern. GPR  images can be processed to compensate for these effects, and this is usually carried  out offline. A GPR can be designed to detect specific targets such as interfaces in  roads, pipes, and cables by means of polarized radiation and localized objects such  as cubes, spheres, and cylinders. 
 This spatial distribution of energy is called scatter - ing, and the object itself is often called a scatterer . The energy scattered back to the  source of the wave (called backscattering ) constitutes the radar echo  of the object. The  intensity of the echo is described explicitly by the radar cross section of the object, for  which the acronym RCS has been generally recognized. 
 Figure 5shows the spatial and temporal baseline for all the interferometric combinations in our experiment. The numbers 0–16 in Figure 5correspond to each SAR image, and number 7 represents the index of the selected super master image (acquired on 14 February 2015). In the two-pass D-InSAR processing, all the rest of the images were registered and resampled to the super master image. 
 R. S. Symons, “Tubes: Still vital after all these years,” IEEE Spectrum , vol. 
 A., and R. Tsu: Theory and Performance of Perpendicular Diffraction De- lay Lines, Proc. IEEE, vol. 
 Likewise, target information without target detection is meaningless. Range.  Probably the most distinguishing feature of a conventional radar is its ability  to determine the range to a target by measuring the time it takes for the radar signal to  propagate at the speed of light out to the target and back to the radar. 
 GAUGE COMPARISON TO OPERATION PRECIPITATION PROFILE  CORRECTIONS v * !PPL -ETEOROL  VOL   PP n    5 'ERMANN AND * *OSS  h-ESOBETA PROFILES TO EXTRAPOLATE RADAR PRECIPITATION MEASUREMENTS  ABOVE THE !LPS TO GROUND LEVEL v * !PPL -ETEOROL  VOL   PP n    " 6IGNAL  ' 'ALLI  * *OSS  AND 5 'ERMANN  h4HREE METHODS TO DETERMINE PROFILES OF REFLECTIV 
 Repr. 2255-70-T or1 Contract :It-.  30(60?1)- 1070, July, 1956. 
 V ﬁtted with AN/APS-15 would be made available to Coastal Command starting in December 1943. The Coastal Command version ofAN/APS-15 became known as ASV Mk. X. 
 Atnetit, W. S.: 'I'oward a 'I'lieory of Reflection by a Rough Surface, Proc. IRE, vol. 
 64. Mengel, J. T.: Tracking the Earth Satellite and Data Transmission by Radio, Proc. 
 These include the following: ch11.indd   22 12/17/07   2:25:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 
 2.6). Antenna Beamwidth. This property of the antenna does not appear explicitly in the range equations, but it affects the range calculation through its effect on the number of pulses integrated when the antenna scans. 
 GENEOUS  SO THAT FIXED THRESHOLDS COULD BE USED (OWEVER  A REALISTIC RADAR ENVIRON 
  B    ! C  
 1022–1028, 1977. 10. J. 
 A multiple-bit diode phase shifter need not be constructed with all of the  same types of phase bits. The loaded-line circuit is often preferred for small phase increments  because of its compact size. It is not as suitable for large phase steps because it is difficult to  match in both states under this condition. 
 The CASH -CFAR threshold very acc urately fits the  clutter sce nario. Moreover, because of the special maximum -minimum process, the threshold  follows steep jumps in clutter level with almost no time displacement. F inally, because of the  selection of the clutter -representative by means of the special maximum -minimum pr ocess the  CASHCFAR requires much less processing power than the OS- CFAR with its rank- selection  method. 
 . È°£n  2!$!2 (!.$"//+  AND THE LIMIT ON THE -4) IMPROVEMENT FACTOR DUE TO THE 34!,/ PHASE NOISE IS  GIVEN BY   )0 
 PANYING TEMPERATURE CHANGE CAN ALSO LEAD TO A TRAPPING REFRACTIVITY GRADIENT 4HE AIR IN CONTACT WITH THE OCEANS SURFACE IS SATURATED WITH WATER VAPOR ! FEW METERS ABOVE THE SURFACE THE AIR IS NOT USUALLY SATURATED  SO THERE IS A DECREASE OF WATER VAPOR PRES 
 [ CrossRef ] c/circlecopyrt2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). 
 The rms noise power  at the output is smaller than the peak power from a point target by the factor BT. A dei~ction  threshold is set somewhere within this range or possible amplitude to allow point targets that  are larger than the background to.be detected. This dispersive CFAR may be placed either  before or after the matched filter. 
 Onthese itisgood practice touseaircraft construction methods. The selection of materials used depends upon the size ofthe reflector and the stresses involved. Magnesium oraluminum alloy will serve forairborne equip- ment. 
 68. Loughren. A. 
 Calibrating weather radar usually means to accurately specify  the radar constant in the radar equation and to accurately estimate the received power  ch19.indd   18 12/20/07   5:38:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 
 thebeamissteerable. Thegeneration ofmultiple fixedbeamsoranumber of independent steerable beamsrequires aduplication ofthesampling pulsegenerators and sampling mixers. Otherbeam-forming methods. 
 Nevertheless, the InSAR method suffers from temporal decorrelation and atmospheric disturbance [ 22–24]. Therefore, many advanced InSAR methods based on multi-interferograms such as persistent scatterer interferometry (PS-InSAR) and small baseline subset interferometry (SBAS-InSAR) have been proposedto overcome these limitations [ 25–29]. Furthermore, high-resolution SAR images are gradually applied such as ALOS-PALSAR and Radarsat-2 images [ 30,31]. 
 Lame, and C. Winn, “NASA scatterometer on NROSS—a system for  global observations on ocean winds,” Dig. IGARSS ’84 , 1984. 
 Target recognition is another example. It is best to use automatic tracking with a good radar that eliminates most of the unwanted signals so that the automatic tracker only has to deal with desired target detections and not undesired clutter. When a radar cannot eliminate all nuisance echoes, a means to maintain a con- stant false-alarm rate (CFAR) at the input to the tracker is necessary. 
 The radar equation with n pulses integrated can be written  where the parameters are the same as that of Eq. (2.7) except that (SIN), is the signal-to-noise  ratio of one of the n equal pulses that are integrated to produce the required probability of  detection for a specified probability of false alarm.'To use this form of the radar equation it is  necessary to have a set of curves like those of Fig. 2.7 for each vaiue of 11. 
 (3.15). The doppler-shifted  echo is heterodyned with the transmitted signal to produce the beat-frequency signal of  Eq. (3.16). 
 SEC. 9.12] EXAMPLES OF MECHANICAL SCANNERS 285. 286 ANTENNAS, SCANNERS, AND STABILIZATION [SEC. 
 WIDTH  HORIZONTAL MARKERS EVERY  CM  VERTICAL SCALE  M #OURTESY )%%   
 LEVEL DIVERGENT OUTFLOW OR MICROBURST  JUST TO RIGHT OF THE CENTER &IGURE  SHOWS ANOTHER EXAMPLE OF PRECIPITATION INTENSITY AND AIR MOTION FIELDS SUPERPOSED ON A PHOTOGRAPH OF A CONVECTIVE THUNDERSTORM CELL 4HE DATA ARE TAKEN FROM THREE DOPPLER RADARS SPACED ABOUT  KM APART ! DEVELOPING NETWORK OF SHORT RANGE DOPPLER RADARS NOT RANGE LIMITED BY THE %ARTHS  CURVATURE WILL PROVIDE MORE DETAILED OBSERVATIONS CLOSE TO THE  SURFACE THAN THE RELA 
 8. A. I. 
 THE 
 The state of the sea is determined primarily by the  Rodar /:.  ·, ··, Dep,ess,on  angle  '·  Grazing ··,,  angle·-· Incidence angle  Figure 13.2 Angles used in describing geometry of  the radar and surface clutter. 474 INTRODUCTION TO RADAR SYSTEMS  strength of the wind and the distance and time over which the wind has been blowing. 
 264. Sensors 2019 ,19, 2605 In [22], it was proposed to divide images into areas of three classes. The ﬁrst class is comprised of homogeneous areas. 
 K : "Radars. vol. 6. 
 77.Dyer.F.B..N.C.Currie.andM.J.Applegate: RadarBackscatter fromLand.Sea.Rain.andSnowat Millimeter Wavelengths. IlItematiO/wl COII(i.'rellce RADAR-n. pp.559-563. 
 1959.  11. Mendel. 
 Grating lobesappearat±90°whend=A.Foranonscanning array(whichiswhatiscon­ sideredhere)thiscondition (d=A)isusuallysatisfactory fortheprevention ofgratinglobes. Equation 8.3appliestoisotropic radiating elements, butpractical antenna elements thatare dcsignedto maximize theradiation at0=0°,generally havenegligible radiation inthedirec­ tion(1=±90°.ThustheefTectofarealisticelement patt~rnistosuppress thegratinglobesat ±90°.Itisforthisreasonthatanelementspacingequaltoonewavelength canbetolerated for anonscanning array. FromEq.(8.3),Ea(O)=Ea(rr-0).Therefore anantenna ofisotropic elements hasa similarpatternintherearoftheantennaasinthefront.Thesamewouldbetrueforanarrayof dipoles. 
 18.)  26. Howard, D. D.: Single Aperture Monopulse Radar Multi-Mode Antenna Feed and Homing Device,  Proc. 
 2, pp. 6-13,  Summer, 1975.  7. 
 I>. Howard: Precision Tracking with Monopulse Radar, Electrorrics, vol. 33, no. 
 T11E iI'l.li(~~TKONI('AI.1.Y STf:ERF:I> I'IIASED ARRAY ANTENNA IN RADAR 325  ing oli the conlputer resources, herice it is necessary to exclude information that is of no  iriterest to the systeni. Such unwanted iriforniation may be from clutter, interference, or  ian~riling. Iii principle, the computer can be progranirned to recognize and reject these un-  \v;~riteri signiils. 
 For railways, CW radar  can be used as a speedometer to replace the conventional axle-driven tachometer. In such an  application it would be unaffected by errors caused by wheelslip on accelerating or wheelslide  when braking. It has been used for the measurement of railroad-freight-car'velocity during  humping operations in marshalling yards, and as a detection device to give track maintenance  personnel advance warning of approaching trains. 
 Mirror-Scanned Antenna (Inverse Cassegrain).  An antenna technique that  uses a movable RF mirror for scanning the beam, called a mirror-scanned antenna  or  inverse Cassegrain,  provides useful applications to monopulse radar. The technique  uses a radome-supported wire-grid paraboloid that reflects parallel-polarized feed  energy. 
 Although thisregion hasbeen until now ofnointerest forradar applications, onecan anticipate thedevelopment ofshort-range, very-high-resolution radar forwhich thc nearzone, sodefined, willbe.ofprimary importance.. 20 THERADAR EQUATION [SEC. 22 radiate awell-defined beam. 
 D.  Warner132) FIGURE   16. 30 Angular response of the scattering coefficient for five moist fields with different roughness at  (a) 1.1 GHz, ( b) 4.25 GHz, and ( c) 7.25 GHz ( after F . 
 Consideration ofallthese points leads tothe conclusion that apulse length greater than about 2psec istobeavoided. Upper limits imposed onpulse power and onthe pulse recurrence frequency have been such that adecrease inpulse length below 1~sec would require adecrease inaverage power below the maximum safe value, resulting inadecrease ofR-,.Further, asweshall see, al-psec pulse yields adiscrimination inrange which is,formost ofthe area covered bythe radar, roughly equal tothe azimuth discrimination afforded bythe beamwidth chosen. This isdesirable from the stand- point oftheindicator. 
 He also  reviews more recent empirical data. The greatest uncertainty in prediction of attenuation rates caused by rainfall,  when theoretical formulas are used as a basis for calculation, is the extremely lim - ited knowledge of drop-size distributions in rain of varying fall rates under differ - ing climatic and weather conditions. Lhermitte25 and Uijlenhoet et al.50 thoroughly  review the evolution of analytic expressions for drop-size distributions, describing  the Marshall-Palmer experiment and their resulting exponential distribution and the  more general three-parameter Gamma distribution. 
 I EE£ J 975  International Radar C01!f"erence, Arlington, Va .. Apr. 21-23, 1975, pp. 
 (Approved for public release.) . CHAPTER  TWELVE  PROPAGATION OF RADAR WAVES  12.l INTRODUCTION  The propagation of radar waves is affected by the earth's surface and its atmosphere. Complete  analysis or prediction or radar performance must take into account propagation phenomena  since most radars do not operate in "free space" as was as~umcd in the ideal formulation of  the radar equation in Chaps. 
 This correlation is amplified and subtracted from the appropriate quiescent weight Wqli or Wq2i to obtain the slowly varying weight Wn or W12. The quiescent weight is the product of the antenna illumination factor for the /th element that will yield the desired antenna pattern and the MTI weight for the delayed or undelayed pulse. This would include the phase component required to steer the beam in a given direction. 
 ,- 3PACE 
             .   39.4(%4)# !0%2452% 2!$!2   £Ç°ÓÇ 4HE CORRESPONDING VELOCITY SEPARATION IS  $V   o FVIB K   AND THE CROSSRANGE  DISPLACEMENT IS THEN   $$ 7$RVV 62F2     oVIB AVG 6L     WHERE K AVG   AVERAGE WAVELENGTH ASSUMING LOW FRACTIONAL BANDWIDTH  4HE RELATIVE  AMPLITUDE OF EACH OF THE PAIRED ECHOES IS   6OLTAGE   FP LOD   AVG      0OWER   F P LO D ¤ ¦¥³ µ´ ¤ ¦¥³ µ´AVG    4HUS  THE AMPLITUDE OF THE PAIRED ECHOES IS  PROPORTIONAL TO THE SQUARE OF THE VIBRA 
 Dig., pp. 941-944, June 1987. 17. 
 EXTRAC71ON OF INFORMATION AND WAVEFORM DESIGN 437  Nonlinear-contact effects (METKRA).~' When metals come in contact with each other it is  possible for their junctions to act as nonlinear diodes. The nonlinear properties of such  junctions can be used to recognize metallic from nonmetallic reflectors when illuminated by  radar. This technique lias sometimes been called METRRA, which stands for Metal Reradiat-  ing Radar.48 Most solid, meclianical, metal-to-metal bonds and properly made solder joints  do not show nonlinear effects. 
 Sidelobe-Blanking (SLB) System. The purpose of an SLB system is to prevent the detection of strong targets and interference pulses entering the radar receiver via the antenna sidelobes.21"24 A method of achieving this is to employ an auxiliary antenna coupled to a parallel receiving channel so that two signals from a single source are available for comparison. By suitable choice of the antenna gains, one may distinguish signals entering the sidelobes from those entering the main beam, and the former may be suppressed. 
 Repeater "false echoes" can be unmasked as such by  tltilizing in an unpredictable manner different pulse repetition frequencies, rf freqirencies, pt~lse  widths, internal pulse modulations, or polarizations. Sidelohe bliinkers can prcvent repeater  signals from entering the radar via the antenna sidelobes and appearing on the display ill  directions different from that of the jammer. In a tracking radar, circuitry can be devlscri to  prevent range-gate stealers from capturing the range gate. 
 FICIENTLY ACCURATE TO PLACE THE PENCIL BEAM ON THE TARGET  OR IT MAY REQUIRE THE TRACKER TO SCAN A LARGER REGION OF UNCERTAINTY 4HE RANGE 
 The easiest way tokeep transmitter power out ofthe receiver isto useseparate transmitting and receiving antennas, and this was thecourse adopted. With amoderate amount ofwork ontheantennas, theleakage from transmitter toreceiver can bemade tobeofthe order l(FS orlees inpower. Another power of10iscanceled byanadjustable leakage path from transmitter toreceiver. 
 Pierson, W. J., G. Neumann, and R. 
 TUNING DRIFT 3TRETCH 0ROCESSING  )N STRETCH PROCESSING  THE ,/ SIGNAL FREQUENCY IS MODULATED  WITH A CHIRP WAVEFORM SIMILAR TO THAT OF THE RECEIVED SIGNAL TO REDUCE THE BANDWIDTH OF THE )& SIGNAL AS DESCRIBED IN 3ECTION  4HE WIDEBAND CHIRP WAVEFORM IS TYPICALLY GENERATED BY PASSING A NARROWER BANDWIDTH LINEAR FREQUENCY MODULATION ,&-  WAVE 
 In prac-  tice, phase variations across the aperture, poor polarization characteristics, and antenna mis-  match reduce the efficiency to the order of 55 to 65 percent for ordinary paraboloidal-reflector  antennas.  Feed support. The resonant half-wave dipole and the waveguide horn can be ahanged to fed  the paraboloid as shown in Fig. 
 Early papers on the subject called it the echo area or the effective area, terms still found occasionally in contemporary technical literature. The formal definition of radar cross section is . \E I2 a = Hm 4ir/?2 -^- (11.1) /?-+oc If0"2 where E0 is the electric-field strength of the incident wave impinging on the target and Ex is the electric-field strength of the scattered wave at the radar. 
 26. Berg, A. A.: Radar Indicators and Displays, chap. 
 Again, the trade-off must be performed  between system dynamic range and noise figure. Definitions.  Dynamic Range represents the range of signal strength over  which the receiver will perform as expected. 
 The portions of the output waveform other than the spike are called  tin~r sitlelobes.  The binary choice of 0 or n phase for each subpulse may be made at random. However,  some random selections may be better suited than others for radar application.66 One criterion  for the selection of a good "random" phase-coded waveform is that its autocorrelation func-  tion should have equal time-sidelobes. 
 SURFACE SOUNDING ARE   RANGE 
 6,  pt. 4, pp. 5- 14, 1958. 
 174–180, March 1968. 42. H. 
 HIGH APERTURE PROVIDED SUFFICIENT GAIN  AND ANGULAR RESOLU 
 IEEE J. Sel. T op. 
 The authors introduced the concept and the design of the system, and presented ﬁrst results derived by using the developed prototype. The work in [ 9] concerns a GBSAR system consisting of an antenna on a rotating boom that performs a 360-degree scanning of the surrounding scene, namely, an ArcSAR system. In order to improve the quality of the ArcSAR imaging, the authors propose a reﬁnement of the image focusing by using a digital elevation model (DEM) derived through interferometric processing. 
 The height of the reference plane was 0 m. Based on Equations (17)–(19) in Section 3.2, we found the defocused area and focused area of the distributed scenes imaging results on the reference plane, as shown in Figure 21.   Figure 21. 
 THE 
 andreducetheimprovement factorthatcanbeachieved inMTIprocessors. Itshouldtherefore be used withcaution asanECCMdevice.Ifincorporated inaradar,provision shouldbe included forswitching itoutofthereceiver whenitdoesmoreharmthangood'J Acollstalltfalse-a/arm ratt'(CFAR)receiver isusedwithautomatic detection systcms to keepthefalse-alarm rateconstant asthenoiselevelatthereceiver varies(Sec.10.7).Without CFARthecomputer inautomatic systems canquickly become overloaded andceaseto function. CFARissometimes classedasanECCM, butinrealityitisnotinthesamecategory asotherECCM.CFARdoesnotgiveimmunity tojamming; itmerelymakesoperation inthe presence ofjamming moreconvenient byautomatically reducing theeffective sensitivity ofthe receiver.Ifthejamming issevereenough,CFARcanproduce almostthesameeffcctasturning offthereceiver. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Cross Section. 14.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 The high-power instrumentation of yesteryear has been largely replaced on static test  ranges with coherent stepped-frequency radars that are far more versatile, but high- power systems remain useful for dynamic testing of targets flying or sailing past them  on dynamic test ranges. 
 Variations involtage, tem- perature, and pressure allproduce frequency changes. Frequent tune-up bythe operator, using echoes, isnot dependable since serious deteriora- tion inthe sensitivity ofaradar, such asthat caused bydrifting out of tune, isnot immediately obvious onthe scope. Also, inaship onthe open ocean orinanairplane over the ocean, there may often beno ‘WtargetsFor these reasons, anautomatic- frequency-control circuit, AFC, has come tobeastandard part ofallradar sets. 
 FREQUENCY TRANSMITTER POWER SUPPLY RIPPLE 4HESE LIMITER SETTINGS CAUSE THE RESIDUE DUE TO TRANSMITTER NOISE AND THE RESIDUE DUE TO OTHER INSTABILITIES  SUCH AS QUAN 
 DESIGNED DISPLAYS ARE VIEWABLE OVER A WIDE VARIATION OF AMBIENT LIGHTING THEY MAKE EFFECTIVE USE OF COLOR AND GIVE EASY AND CLEAR ACCESS TO THE RADAR IMAGE AND ASSOCIATED DATA 4HE DAYS WHEN THE RADAR SCREEN WAS ONLY VIEWABLE IN DAYLIGHT ON DIM LONG 
 Weijers, “Fully polari - metric bistatic radar scattering behavior of forested hills,” IEEE Trans . AP-5O(2), pp. 101–110,  February 2002. 
 Variation withgrazingangle.Thereareusuallyidentified threescattering regionsaccording tothegrazingangle.Atnearverticalincidence (4)~90°)theradarechoisrelatively large. Thisiscalledthequasi-specular regionandseemstobetheresultofspecular scatterfrom facetlike surfaces oriented perpendicular tothedirection oftheradar.Attheotherextreme, whenthegrazinganglesare.lowt' oftheorderofseveraldegreesorless,0'0decreases very rapidlywithdecreasing angle.Thisiscalledtheinterference regionsincethedirectwaveand. RADAR CLUTTER 475  X AND L  (VERT. 
 For short-range operation (down to 100 ft) the TWT is by- passed to reduce the power on the target. Five RF frequencies are used in the radar mode to decorrelate Swerling 1 (slowly fluctuating) target returns and im- prove detection. A 16-point digital Fourier transform (DFT) processor is em- ployed to coherently integrate multiple pulse returns and to provide fine- resolution measurements of target relative velocity. 
 The  spacecraft off-nadir angle is also estimated from the  V A IT. The measurement is only valid over the ocean  where the waveforms are well behaved and predictable.  A distribution of altimeter-derived off-nadir pointing for  a typical day is shown in Fig. 
 When the swath is significantly less than the unambig-  uous range, a buffer can be inserted after the AID convertors to read the data out at a slower  speed so as to process at a lower data rate than if the entire unambiguous range had to be  imaged. Digital processing also allows the use of a nonlinear sweep to convert slant range to  ground distance so as to make distances correct on the image.  Doppler-frequency model. 
 Case2.Theprobability-density function forthetargetcrosssectionisalsogivenbyEq.(2.39£1), hutthefluctuatioJls arcmorcrapidthanincase1andarctakcntobeindependent from pulsetopulseinsteadoffromscantoscan. ClISt'3.Inthiscase.thefluctuation isassumed tobeindependent fromscantoscanasincase I.huttill'plohahility-dcnsity function isgivcnby (2.39b) ./Cast'4.Thefluctuation ispulsetopulseaccording toEq.(2.39b) Theprobability-density function assumed incases1and2appliestoacomplex target consisting ofmanyindependent scatterers ofapproximately equalechoingareas.Although, in theory,thenumber ofindependent scatterers mustbeessentially infinite, inpractice the numbermaybeasfewasfourorfive.Theprobability-density function assumed incases 3and 4ismoreindicative oftargetsthatcanberepresented asonelargerellector together withother smallrellectors. Inalltheabovecases,thevalueofcrosssectiontobesubstituted intheradar equation istheaverage crosssection eTav•Thesignal-to-noise rationeededtoachievea specified probability ofdetection withoutexceeding aspecified false-alarm probability canbe calculated foreachmodeloftargetbehavior. 
 FEED RADAR REFLECTOR ANTENNAS SUCH AS THOSE DEPICTED IN &IGURES    MECHANICAL SCANNING IS GENERALLY ACHIEVED VIA A GIMBAL A PRECISION MECHANICAL POINT 
   ,UNAR SUBSURFACE      -(Z -!23)3  -ARS %XPRESS n -ARS SUBSURFACE        -(Z 3(!2!$  -2/ n -ARS SUBSURFACE   
 781-789, July, 1978.  68. Williams, P. 
 There it is stated  that “one of the principal advantages of an AESA is the ability to manage both power  and spatial coverage on a short-term basis (10s of ms).” It is also said that “bandwidth  of several GHz on transmit” is required, and this is within the capability of solid-state  transmitters. The reader is referred to Section 5.1, Chapter 11, and Section 13.10 for  further information about this important application of solid-state. Although any of the RF power sources mentioned here could be used in future  radar systems, it seems likely that the linear-beam amplifier, particularly one of the  variants of the klystron, might be the first RF power source to consider for a high  performance microwave radar that employs a mechanically steered antenna or a con - ventional phased array radar that does not employ the active aperture. 
 , (211 + 1 )rr/2, where n = 0, 1, 2, .... The maxima are therefore defined by  41ta Ii, = 211 + 1  )..R maxima (12.6)  The minima, or nulls, occur when the sine term is zero, or when  i 2h0h, )jf=n mm1ma (12.7)  Thus the presence of a plane reflecting surface causes the continuous elevation coverage to  break up into a lobed structure as indicated in Fig. 12.2. 
 BINER FOR A RANGE OF AMPLITUDE AND PHASE IMBALANCES BETWEEN TWO COMBINED AMPLIFIERS 7ITH AN  AMPLITUDE IMBALANCE OF  D" AND A PHASE IMBALANCE OF n  APPROXIMATELY  D" OF POWER WILL BE LOST TO THE ISOLATING TERMINATION OF THE POWER COMBINER#ONTOURS OF 6ECTORAL 0OWER ,OST    !MPLITUDE )MBALANCE D" 0HASE )MBALANCE DEG  D"D" D" D" D" D" D" D" D" D"D"D". ££°ÓÓ  2!$!2 (!.$"//+  )N GENERAL  THE REQUIREMENTS FOR A POWER COMBINER ARE L 4HE COMBINER SHOULD HAVE LOW INSERTION LOSS TO MAXIMIZE TRANSMITTER EFFICIENCY L 4HE COMBINER SHOULD HAVE 2& ISOLATION AMONG PORTS  SUCH THAT FAILED MODULES DO NOT  AFFECT THE LOAD IMPEDANCES OR COMBINING EFFICIENCY FOR THE REMAINING FUNCTIONING  MODULES L 4HE COMBINER SHOULD PROVIDE A CONTROLLED 2& IMPEDANCE TO THE AMPLIFIER MODULES   SUCH THAT THE AMPLIFIER CHARACTERISTICS ARE NOT DEGRADED L 4HE DISSIPATED POWER CAPABILITY OF THE POWER COMBINER TERMINATIONS SHOULD BE SUF 
 £  MAX     TO WHICH THE DOPPLER STRADDLING LOSS WOULD HAVE TO BE ADDED 3UBCLUTTER 6ISIBILITY 3#6    4HE )%%% DEFINITION OF SUBCLUTTER VISIBILITY IS 3UBCLUTTER VISIBILITY  4HE RATIO BY WHICH THE TARGET ECHO POWER MAY BE WEAKER THAN COINCIDENT  CLUTTER ECHO POWER AND STILL BE DETECTED WITH SPECIFIED DETECTION AND FALSE 
 vol. 110. pp. 
  
 The procedure was developed for a single-delay canceler and a nonscanning antenna. Andrews used the procedure to minimize the residue power over the full antenna pattern, which includes the main-beam and sidelobe regions. 76.7 PLATFORM-MOTION COMPENSATION, FORWARD DIRECTION The previous sections discussed the compensation for the component of platform motion parallel to the antenna aperture. 
 SCAN PHASED ARRAY RADAR  )N SOME CASES  TRACKING LAG IS MEASURED BY CONVERTING TRACKING 
 In the transmission equation, Eq. (2.1), Pt and Pr are the transmitted and re- ceived powers at the antenna terminals. As was mentioned in Sec. 
 In both the sequential-lobing and conical-scan techniques, the measure­ ment of the angle error in two orthogonal coordinates (azimuth and elevation) requires that a  minimum of three pulses be processed. In practice, however, the minimum number of pulses in  sequential lobing is usually four-one per quadrant. Although a conical scan radar can also be  operated with only four pulses per revolution, it is more usual to have ten or more per  revolution. 
 Radar. I. Title. 
 1960.  26. Rattan. 
 V.. and J. D. 
           
 CENTERED OVAL OF #ASSINI )T HAS AN ^ D" GREATER LINK MARGIN  WHICH WAS FIRST USED FOR -ARS /DYSSEY AND IS PLANNED FOR FUTURE PROBES )N BOTH CONFIGURATIONS  EVEN THOUGH TWO LEGS OF THE BISTATIC TRIANGLE ARE EXTRAORDINARILY LONG    MILES   THE THIRD LEG IS SUFFICIENTLY SHORT  ^ MILES  TO PRODUCE STRONG ECHOES AT THE RECEIVER 4HESE PIGGYBACK BISTATIC RADARS HAVE PROVIDED USEFUL DATA IN SIMPLE  INEXPENSIVE  SURVEYS OF PLANETARY SURFACE PROPERTIES AS A PRELUDE TO ROBOTIC OR HUMAN EXPLORATION  SPECIFICALLY CENTIMETER 
 47. Knerr, R.H.: An Annotated Bibliography of Microwave Circulators and Isolators: 1968-1975, /EEE  Trans .. vol. 
 If the main reflector is circular and  assumed to have a completely tapered parabolic illumination, a small circular obstacle in the  center of the aperture will reduce the (power) gain by approximately [l - 2(Db/D)2]2, where  I),, is the diameter of the obstacle (hyperbolic subreflector) and D is the diameter of the main  aperture.19 The relative (voltage) level of the first sidelobe is increased by (2Dh/D)2. For  exariiple if D,/D = 0.122. the gain would be lowered by about 0.3 dB and a -20 dB sidelohe  would hc increased to about - 18 dB. 
 In order to create the change maps, images are cross-correlated pixel-by-pixel to detect the changes. 2CMV products show changes at the pixel level and are often misleadingly dominated with red and cyan colors. Figure 1 shows a portion of a sample 2CMV image. 
 Ifnlexceeds n.zbysome very small amount ~,both nland nzbeing very nearly unity, awave incident ontheboundary CDatagrazing angle a wader than V% will experience total internal reflection. Under such conditions theregion between ABand CDcanberegarded astheinterior ofawaveguide bounded bytwo reflecting surfaces. But inanordinary ,.. 
 Thereisnostandard, agreed-upon methodforspecifying thesingle-valued crosssectionofanaircraft.Theaveragevalueorthemedianmightbetaken. Sometimes itisa"minimum" value,perhapsthevalueexceeded 99percentofthetimeor95 percentofthetime.Itmightalsobethevaluewhichwhensubstituted intotheradarequation assuresthatthecomputed rangeagreeswiththeexperimentally measured range. Table2.2lists"example" valuesofcrosssectionforvarious targetsatmicrowave frequencies. 
 Maher: Effect of Surface Reflections on Rain Cancellation of Circularly  Polarized Radars, IRE Trans., vol. AP-7, pp. 199-201, April, 1959. 
 23.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 23.8 SURFACE CLUTTER The bistatic radar cross section of surface clutter, sc, is a measure, as is the monostatic  radar clutter cross section, of the energy scattered from a clutter cell area, Ac, in the direc - tion of the receiver. It is defined as σ σc B cA =0, where σB0 is the scattering coefficient,  or the clutter cross section per unit area of the illuminated surface. The clutter cell area  Ac has been developed for beam- and range-limited cases and is reported elsewhere.1,2  Doppler-limited cases are a function of platform motion, which, in turn, depend on a  specific scenario. 
   %XPLORER 
 FEED SYSTEM USES MANY STEPS &OR A HIGH 
 STAGGERED DOPPLER FILTER OUTPUTS ARE REQUIRED TO MAINTAIN A SET OF TEMPORAL DEGREES  OF FREEDOM IN THIS ARCHITECTURE 4HE BLOCK DIAGRAM IS MODIFIED TO THAT SHOWN IN &IGURE   WITH MULTIPLE DOPPLER FILTER BANKS ON EACH ANTENNA ELEMENT AND 02) DELAY 0OST 
 CONCEPT INSTRUMENT THAT HAD A SOLID 
 V . W. Hammond and K. 
 The output fluctuation Ayisgiven by Ay=$Ax, and werequire ittobeindependent oftheclutter amplitude z. Thus we have dy= K z kx+N’ where Kisthe(constant) value ofAy. Integrating this equation with the condition that y=Owhen z=O,wegetthefollowing expression forthe characteristic ofthei-famplifier: (12) For values ofxgiving afluctuation kxconsiderably less than noise,the characteristic islinear. 
 M.: Monopulsc Radar. IRE Natl. Conv. 
 M. Kirkpatrick: Effect of Internal Fluctuations and Scanning on  Clutter Attenuation in MTI Radar, IRE Trans., vol. ANE-2, pp. 
 - !LTHOUGH THE 2& POWER 
 Denenberg, J. N., R. J. 
 CALLED !& #OAXITRON  DESCRIBED IN 6INGST ET AL   OPERATED OVER A  FREQUENCY RANGE FROM  TO  -(Z WITH A PEAK POWER OF  -7  A PULSE WIDTH OF  §S  A DUTY CYCLE OF   AN AVERAGE POWER OF JUST UNDER  K7  AND A PLATE EFFICIENCY OF  4HE #OAXITRON HAS BEEN SUCCESSFULLY EMPLOYED FOR 5(& RADARS  INCLUDING AIRBORNE #ONSTANT %FFICIENCY !MPLIFIER #%!   )T HAS BEEN SAID  THAT hA CONSTANT 
 BASED DEPLOYABLE REFLECTOR 4HE MESH REFLECTOR   SHOWN IN BOTH STOWED AND DEPLOYED CONFIGURATIONS IN &IGURE   IS AN OFFSET REFLEC 
 The learning rate often been reduced by a factor of 0.1 or 0.5. 2.3. Proposed Method with T ransfer Learning 2.3.1. 
 Paige: Surface-Acoustic-Wave Devices for Signal Processing Applications,  Proc. IEEE, vol. 64, pp. 
 So this quantity is used as squared in the  equation.   External and Internal Losses   This is  the sum of all loss factors of the radar. This is a value  that is calculated to compensate for attenuation by precipitation,  atmospheric gases, and receiver detection limitations. 
 1l.2INFORMATION AVAILABLE FROMARADAR Aradarobtainsinformation aboutatargetbycomparing thereceived echosignalwiththe transmitted signal.Theavailability ofanechosignalindicates thepresence ofareflecting target;butknowing atargetispresentisoflittleusebyitself.Something moremustbeknown. Therefore, aradarprovides thelocationofthetargetaswellasitspresence.Itcanalsoprovide information aboutthetypeoftargetThisisknownastargetclassification. Thetimedelaybetween thetransmission oftheradarsignalandthereceiptofanechoisa measure ofthedistance, orrange,tothetarget.Therangemeasurement isusuallythemost significant aradarmakes.Noothersensorhasbeenabletocompete withradarfordetermin­ ingtherangetoadistanttarget.Atypicalradarmightbeabletomeasure rangetoanaccuracy 399. 
 LAR RANGE OF FREQUENCIES HAS BEEN CHOSEN  (OWEVER  IT CAN BE SHOWN THAT CONSIDERABLE  VARIATIONS n D"  IN THE SENSITIVITY OF COMPETING SYSTEM DESIGNS ACTUALLY TRANSLATE TO RELATIVELY SMALL CHANGES IN DEPTH PERFORMANCE IN LOSSY SOILS 4HE SELECTION OF A SUITABLE WAVEFORM FOR TRANSMISSION  AT LEAST IN TERMS OF RESOLU 
 Johnson: Clutter Suppression by Use of Weighted Pulse Trains, RC.4 Rev.,  vol. 32, pp. 402-428, September, 1971. 
 % RADAR AND  THROUGH A BILATERAL TECHNOLOGY EXCHANGE PROGRAM  THE (* 
  COTA  ]      6   K F"  COSC   K F-   COSC  
 ZERO DIAGRAMS 4HE  : PLANE IS THE COMB 
 More detailed discussions of the characteris - tics of these architectures are included in Section 12.3 wherein each of these architectures  is afforded a dedicated subsection. Another means of classification is via platform (vehi - cle) or site (ground-based, ship-based, airborne, or space-borne). The platform frequently  drives mechanical and environmental requirements and often either enables or constrains  the reflector size. 
 The high-resolution SAR image inversion needs to be investigated in future work. Author Contributions: X.H. and X.L. 
 P. Meyer and H. A. 
 Frisch, C. G. Little, D. 
 The boundaries of the various regions are wide to indicate the wide J variation of the data within the classes of terrain. Figure 13.9 illustrates airborne data at X and  L bands obtained by the Naval Research Lab~ratory.~' The azimuth beamwidth was 5" and  the pulse width was 0.5 1s at each frequency. The lack of smoothness of the data IS due, in  part, to the fact that the data was not all taken at the same time. 
 A more satisfactory method of  operation is to form the sum and difference patterns in the RF and to process the signals as in a  conventional amplitude-comparison monopulse radar.  In one embodiment of the phase-comparison principle as applied to missile guidance the  phase difference between the signals in two fixed antennas is measured with a servo-controlled  phase shifter located in one of the arms.27 The servo loop adjusts the phase shifter until the  difference in phase between the two channels is a null. The amount of phase shift which has to  be introduced to make a null signal is a measure of the angular error. 
 They are also limited by their inability  to handle magnetoionic effects on propagation. Nevertheless, they provide closed form  expressions for group range, phase path, ground range, and other parameters, and there - fore, can be very useful for computationally intensive studies such as system optimiza - tion. The multi-quasi-parabolic (MQP) model of Hill47 based on Croft’s QP technique48  is widely used, while quasi-cubic models have been proposed by Newton et al.49 Numerical ray-tracing codes are versatile and able to accommodate almost arbi - trary ionospheric structure, at the expense of computational burden. 
 M., and E. R. Graf: Frequency-Agility Processing to Reduce Radar Glint Pointing Error,  IEEE Trans., vol. 
 Any use is subject to the Terms of Use as given at the website. The Radar Transmitter.  THE RADAR TRANSMITTER  10.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 and the nature of the interaction that produces amplification. Transit-time effects, which  limit the high frequency performance of grid-controlled tubes, are taken advantage of in  linear-beam tubes to velocity modulate the uniform electron beam to create bunches of  electrons from which RF energy can be extracted at the output of the tube. 
 2.8 is thefcllse-alarm n~tnihrr, as introduced by  Marcum.1° It is equal to thereciprocal of the false-alarm probability P,, defined previously by  Eqs. (2.24) and (2.25). Some authors, like Marcum, prefer to use the false-alarm number  instead of the false-alarm probability. 
 The AN/SPS-40 was an existing UHF, tube-type, long-range, 2D shipboard search radar system, for which a new solid-state transmitter, built for the Naval Sea Systems Command by the Westinghouse Electric Corporation, replaced the tube transmitter.10 The existing waveform from the original trans- . mitter was not changed, and the solid-state unit was installed as a direct retrofit. This was not quite as difficult as usual, because the tube-type system already used long pulses and pulse compression, with a duty cycle of nearly 2 percent, which is a lot higher than older 0.1 percent duty cycle systems. 
 11 2  2. The rise in the sidelobe level due to random errors is independent of the beam scan  angle.110  3. The lower the design sidelobe level, the greater will be the rise in the sidelobes, assuming a  given antenna size and a given error tolerance. 
 259–264, June 2004. 20. D. 
 4. W. V . 
 TERM COHERENT CHANGE DETECTION IS A METHOD IN WHICH TWO COHERENT 3!2 MAPS TAKEN WITHIN A FEW HOURS OF ONE ANOTHER AT THE SAME FREQUENCY ARE REGISTERED AND CROSS 
 BEAM PEAK FOR ALL RESPONSES BEYOND THREE IMPULSE WIDTHS OF THE COMPRESSED SIGNAL !MPLITUDE AND PHASE LINEARITY WERE CON 
 2014 ,155, 366–376. [CrossRef ] 13. Sowter, A.; Amat, M.B.; Cigna, F.; Marsh, S.; Athab, A.; Alshammari, L. 
 Input Input High precision  ArcSAR imageOutput DEM im age of the scenesOutputAntenna rises  a distanceArcSAR Image 1 ArcSAR  Image 2 Using polar coordinate  transformation method to  transform DEM image from  slant range to ground rangeExtracting DEM  of scenesDEM assisted  ArcSAR imaging Figure 6. Flow chart of the proposed high precision ArcSAR imaging method. 4.1. 
 J. Ward, Space-Time Adaptive Processing for Airborne Radar , Technical Report 1015, Lexington,  MA: Lincoln Laboratory, Massachusetts Institute of Technology, 1994. 46. 
 363–374. 30. M. 
 REGULATOR FEEDBACK LOOPS &IGURE   4HE FIRST LOOP IS A SECOND 
 andbinary-shift-register sequences. Although thesequence isaseriesofzerosor ones.forapplication tothephase-coded pulse-compression radarthezeroscanbeconsidered ascorresponding tozerophaseandtheonesto1tradiansphase. Sinceanm-sequence takesonallpossible statesexceptthezerostate,theinitialstateof theshiftregisterdoesnotaffectthecontentofthesequence, butwilldefinethestartingpointof thesequence. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 8.40  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 Ambiguity Functions .2,71,72,77 –79 The autocorrelation† function for a transmit  waveform with complex envelope u(t) is defined as   χ τ τπ u dj f tf u t u t e dtd ( , ) ( ) ( ) = +∗ −∞∞ ∫2  (8.48) where t is the relative time delay and fd is doppler shift. 
 For example, if the three frequencies/1,/2, and/3 are such that/3 -/1 = k(f2 -/1), where  k is a factor of the order of 10 or 20, the pair of frequencies /3, /1 gives an ambiguous but  accurate range me: -;urement while the pair of frequencies /2, f, are chosen close to resolve  the ambiguities in the /3, f1 measurement. Likewise, if further accuracy is required a fourth  frequency can be transmitted and its ambiguities resolved by the less accurate but unambiguous  r11cas11rcmcnt ohtained from the three frequencies .f1, /2, /3• As more frequencies are added.  the spectrum and target resolution approach that obtained with a pulse or an FM-CW  waveform. 
 The exact methods are based on either the integral or differential form of Maxwell's equations. Maxwell's four differential equations con- stitute a succinct statement of the relationship between electric and magnetic fields produced by currents and charges and by each other.22 The four equations may be manipulated for isotropic source-free regions to generate the wave equation V2F + ^2F = O (11.5) where F represents either the electric field or the magnetic field. Equation (11.5) is a second-order differential equation which may be solved as a boundary-value problem when the fields on the surface of the scattering obstacle are specified. 
 SCANNING RATE MUST BE AT THE TRANSMITTERS  PULSE PROPAGATION RATE  MODIFIED BY THE USUAL GEOMETRIC CONDI 
 Transmitted waveform and the ambiguity function. The particular waveform transmitted by a  radar is chosen to.satisfy the requirements for (I) detection, (2) measurement accuracy,  (3) resolution, (4) ambiguity, and (5) clutter rejection. The ambiguity function and its plot, the  418INTRODUCTION TORADAR SYSTEMS Figure11.12Ambiguity diagram forasinglefrequency­ modulated pulse.(Alsocalledthechirppu""e-compression waveform.) particular waveform isnotentirelysatisfactory. 
 vol.III,"R.CHansen (ed.),Academic Press,NewYork,1966,pp.217-288. l)l.Shelton, J.P.:Multibeam PlanarArrays,Pro£'.IEEE,vol.56,pp.1818-21, November, 1%8. 92.Nester,W.H.:TheFastFourierTransform andtheButlerMatrix,IEEETrailS.•vol.AP-16,p.360. 
 Ê/, - // Ê-9-/ 
 47.Dax,P.R.:KeepTrackofthatLow-Flying Attack,MicrowalJes, vol.15,pp.36-42,4753, April,1976. 48.White,W.D.:Low-Angle RadarTracking inthePresence ofMultipath, IEEETraIlS.,vol.AES-lO,pp. 835-852, November, 1974. 
 Occasionally HF radar systems also find applications in  line-of-sight applications at short range. This chapter focuses predominantly on skywave  radar, though much of the discussion applies equally to surface wave radar. Rather than  amalgamate discussion of the two radar configurations throughout the chapter, the  distinctive features of HF surface wave radar are treated separately in an appendix at  the end of the chapter. 
 The parameters obtained by the genetic algorithm are taken as the input initial value of the simplex method, and the output optimized searching results are determined as the ﬁnal solutions. 233. Sensors 2019 ,19, 3073 3. 
 Previous Studies Data Method Subsidence Rate Reference Zhou et al.15 C-band Sentinel-1A images, interferometric wide TOPS acquisition mode, VV polarization, ascending orbit, covering most of Wuhan citySBAS-InSAR −82–18 mm/yr [ 5] Bai et al.12 X-band TerraSAR-X images, stripmap acquisition mode, HH polarization, ascendingorbit, covering major urban areas of Wuhan cityPS-InSAR −63.7–17.5 mm/yr [ 41] Costantini et al.45 X-band COSMO-SkyMed images, stripmap acquisition mode, HH polarization, covering most of HKPS Pair InSAR−80–40 mm/yr [ 42] Benattou et al.36 C-band Sentinel-1A images, interferometric wide TOPS acquisition mode, VV polarization, ascending orbit, covering major urban areas of Wuhan cityPS-InSAR −127–23 mm/yr [ 53] Zhou et al. [ 5] obtained the rate of subsidence in Wuhan city by using SBAS-InSAR method with 15 Sentinel-1A images (April 2015 and April 2016) with 5 m ×20 m (range ×azimuth) spatial resolution. Their results showed that subsidence rates varied from −82 mm/yr to 18 mm/yr, and the maximum rate of subsidence was detected in Houhu of HK. 
 signals changes from instant toinstant, and (2)the great majority of these highlights cannot beidentified with any particular prominent structures inthe city. These bright signals, therefore, must beacci- dental strong reflections produced atrandom byfavorable illumination ofparticular surfaces and byconstructive interference ofreflections from different surfaces within asignal pulse packet ortarget area. “City return” issimilar toground return and seareturn inthat each. 
 An intensity-modulated rectangular display with azimuth angle indicated by the horizontal  coordinate and elevation angle by the vertical coordinate.  D-scope. A C-scope in which the blips extend vertically to give a rough estimate of distance. 
 Inasimple cylindrical cavity made ofcopper and resonant at3000 Me/see initslowest mode, the unloaded Qisabout 15,000. Generally, theQofacavity loaded only bytheresistance ofitswalls depends onthe ratio ofthe volume ofthe cavity tothe product ofthe internal surface area and the skindepth. For cavities ofsimilar shape, theresonant fre- quency joisinversely proportional toalinear dimension ofthe cavity; theskin depth varies asl/fro. 
 The transmitter may be an oscillator, such as a magnetron, that is" pulsed"  (turned on and off) by the modulator to generate a repetitive train of pulses. The magnetron  has prohahly heen the most widely used of the various microwave generators for radar. A  typical radar for the detection of aircrart at ranges of 100 or 200 nmi might employ a peak  power or the order or a megawatt, an average power of several kilowatts, a pulse width of  several microseconds. 
 Radars are employed throughout the world for the purpose of  safely coritrollit~g air traffic en route and in tlic vicinity of airports. Aircraft and ground  vcllicular traffic st large airports are monitored by tliearis of high-resolution radar. Radar  has been used with GCA (ground-control approach) systems to guide aircraft to a safe  landing in bad weather. 
 The half angle of this diffraction cone is equal to the angle between the incident ray and the edge. Unless the point FIG. 11.26 The Keller cone of diffracted rays. 
 PERTURBATION THEORY COULD BE APPLIED 4HE PRINCIPAL PROBLEM WITH THIS APPROACH IS DECIDING WHERE IN THE SURFACE SPECTRUM LIES THE BOUNDARY BETWEEN THE LARGER COMPO 
 Filter covariance  more exact  than traditional  methods— particularly for  long extrapolation  times.More complex  but not  necessarily  more  computation.TABLE 7.5  Advantages and Disadvantages of Employing the Kalman Filter in Dif ferent  Coordinate Frames ch07.indd   35 12/17/07   2:14:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 THE RADAR EQUATION 53  In this form, the range does riot depend explicitly on either the wavelength or the pulse  repetitiori frequency. The irnportarit parariieters affecti~ig range are the total transmitted  energy ~IE,, the transmitting gain ti, tlie erective receiving aperture A,, and the receiver noise  figure F, .  2.10 I'U I SIC I~l<l'l<'l'l'l'iON 1'RISQUII:NCY AN11 UANCrl: AMBICU ITIES  Tlie pillse repetition frequericy (prf) is determined primarily by tlie maximum range at which  targets arc cxl,ectcd. 
 Timing Dependencies.  In coherent radar systems, all local oscillators (LOs)  and clocks that generate system timing are derived from a single reference oscilla - tor. However, this fact alone does not ensure that the transmitted waveform starts  at the same RF phase on every pulse, which is a requirement for coherent systems. 
 DELAY FEEDFORWARD CANCELERS ARE CASCADED IN SERIES   THE OVERALL FILTER VOLTAGE RESPONSE IS  KN SINN O FD4   WHERE  K IS THE TARGET AMPLITUDE    N IS THE NUMBER OF DELAYS   FD IS THE DOPPLER FREQUENCY  AND  4 IS THE INTERPULSE PERIOD  4HE CASCADED SINGLE 
 Under these circumstances, itiscustomary tomount the magnetron anode and thepulse transformer case outside thepressurized shell, with anexternal blower tocool them. The cathode connection tothemagne- tron ismade inapressurized inner compartment, into which gasketed bushings bring thepulse transformer output and themagnetron cathode leads. The waveguide r-fline ispressurized from themagnetron output tothepressurized compartment which houses theduplexer, aswell ason theantenna side. 
 The eddy shape and brightness variations along the eddy spiral in the simulated image appear to be consistent with the ERS-2 SAR image. Under the clockwise direction (the anticyclonic eddy in the northern hemisphere rotates clockwise), the brightness variations along the spiral from the outside to the inside follow the order dark-bright. This result is consistent with the imaging geometry for an idealized anticyclonic eddy in Figure 1. 
 13.3.3  Circuit and Switching Concepts   The main components of an ACC Radar sensor are:   RF frontend  Signal processing   Vehicle interface   The RF frontend contains the oscillator, the transmitting/rece iving duplexer and the receiver.   Today the oscillators are normally constructed at frequencies of 19 GHz or 38 GHz with d u- plication or triplication.  The pulse modulation takes place via the switching. 
 A. Merritt, K. P. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 4.52  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 51. 
 Int. Telemetry  Council , November 1987. 16. 
 The comparative results imply the feasibility and reliability of the aforementioned model and parameter estimation method. Figure 2. Estimated rheological parameters compared with real values in the simulation (the noise level is 0.5 rad). 
 ch10.indd   23 12/20/07   11:09:01 AMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. The Radar Transmitter. 
 l., 1952. (Reprinted in ref. 18.)  24. 
 D" GAIN -EASUREMENTS MADE ON THE MIDDLE !TLANTIC COAST OF THE 5NITED 3TATES SHOW (&  BROADCAST 
 MTT-23, pp. 276-281, March, 1975.  18. 
 Pierson and   L. Moskowitz16 © American Geophysical Union 1968 ) ch15.indd   5 12/15/07   6:16:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 286-296, May 1982. 13. Aronoff, E., and N. 
 A further step in feed development is the four-horn triple-mode feed illustrated in Fig. 18.14.7 This feed uses the same approach as described above but with the addition of a top and bottom horn. This allows the E-plane difference signal to couple to all four horns and uses the full height of the feed. 
 Beverly. Mass .. no date. 
 IEEE Geosci. Remote Sens. Lett. 
 2. pp. 27-33. 
 It requires the specification of three parameters: 1. Minimum signal of interest: This is usually defined as the input signal that produces unity signal-to-noise ratio (SNR) at the receiver output. Occasionally, a minimum-detectable-signal definition is employed. 
 21 Velocity modulation. 2002UI Visihility factor.forclutter.l30INDEX581 VSWR. andisolation inCWradar.72 Wave-interference radar,554 Weather clutter,498-507 Weather effects,onradomes. 
 IEEE, vol. 51, pp. 230-231, January 1963. 
   IDENTICAL HORIZONTAL PASSIVE ROW 
 TION 4O DETERMINE THE COMPOSITE EFFECT OF THE COMPONENTS  IT IS NECESSARY TO ADD THE FAR 
 4  -AY    , 0ETERS  *R  h%ND 
 The modes may not be invoked each  time depending on the geometry between the aircraft and the intended target set. The mode time is broken up into coherent processing intervals (CPI’s). A coher - ent processing interval is segmented, as shown in the bottom row of Figure 5.14. 
 W. L. Gamble, and R. 
 Thistime relationship is called the DUTY CYCLE and may be represented asfollows: Foraradarhavingapulselengthof2microsecondsandapulserepetition rate of 500 cycles per second (pulse repetition time = 2,000 microseconds),the Figure 1.12 - Relationship of peak and average power.average power peak power-----------------------------------------pulse length pulse repetition time------------------------------------------------------------ - = duty cyclepulse length pulse repetition time------------------------------------------------------------ - = duty cycle2µsec 2000µsec,-------------------------- 0.001==. 17Likewise, the ratio between the average power and peak power may be expressed in terms of the duty cycle. In the foregoing example assume that the peak power is 200 kilowatts. 
 The discrepancy reaches a value of about 88 ft for a measured target range of 10 nmi. Spherical Earth: Exact Geometry. Again with reference to Fig. 
 This ' 'burst" of air spreads out radially as it strikes the ground, forming a ring of diverging air about 0.3 to 1 km deep and of the order of 2 to 5 km in diameter. Aircraft, penetrating a microburst, experience first an in- crease in head wind and then a continuous, performance-robbing decrease in head wind, which can cause the plane to crash if encountered shortly before touchdown or just as the aircraft is taking off. More complete descriptions of microbursts and their effects on aviation safety are given by Fujita66'67 and McCarthy and Serafm.68 . 
 The computed hrightness temperatures of Fig. 12.11 do not agree in detail with those  prcscn ted hy others. 4 7 · 5 u 2 The fact that such computations made by different authors do not  always agree precisely need not he a limitation to the radar systems engineer. 
 63. Schelonka, E. P.: Adaptive Control Techniques for On-Axis Radars, IEEE 1975 lmernational Radar  Conference, Arlington, Va., April 21-23, 1975, pp. 
 Dunsmore, M. R. B.: Bistatic Radars for Air Defense, IEE Int. 
 The large-angle spotlight SAR measured data contains information about multiple perspectives of the target. After dividing the data into two parts according to the two viewpoints of forward-looking and backward-looking, the fusion image of multi-angle SAR is obtained by using the algorithm proposed in this paper. The parameters of the system are shown in Table 1. 
 CATIONS 4HE DRAWBACK OF THE GRID 
 It was also noted in[3] that ‘immense trouble ’was experienced in the design of the moving contacts for this turret. These contacts had to carry peak currents of up to 20 A and early designs broke down within a few minutes. Air breakdown across the transmitter capacitorswas also encountered. 
 Palmer, D. S., and D. C. 
  
 33  6.5 False Alarm Rate and Probability of Detection ............................................................... 35  6.6 Radar Detectors ............................................................................................................... 38  7 CW-  and FM- CW Radar ...................................................................................................... 
 ECCM. 1\short-pulse radarcannegatetheoperation ofcertainelectronic countermeasures suchasrange-gate stealersandrepeater jammers, iftheresponse timeoftheECMis greaterthantheradarpulseduration. Thewidebandwidth oftheshort-pulse radaralso hassomeadvantage againstnoisejammers. 
 H. Liu and V . Chandrasekar, “Classification of hydrometeors based on polarimetric radar mea - surements: development of fuzzy logic and neuro-fuzzy systems and in-situ verification,” J. 
 ByMarch 1938, allthese stations—the nucleus ofthefinal Chain-were complete and inoperation under thecharge ofRAF personnel. British radar development effort was then brought tobear onairborne radar equipment. Two types were envisaged: asetforthedetection of surface vessels bypatrol aircraft (called ASV, forairtosurface vessel), 1op.ant.. 
 HOUR ORBIT PERIOD  'RAPHIC  COURTESY OF .!3!  . 
 SYNCHRONOUS ORBITS ARE LESS THAN OPTIMUM FOR MOST ALTIMETRIC APPLICATIONS  DUE PRIMARILY TO THE FACT THAT FOUR OF THE EIGHT DOMINANT TIDAL CONSTITUENTS ARE SUN 
 17.Sondergaard. r.:ADualModeDigital Processor forMedium Resolution Synthetic Aperture Radars. IIIC('I'/fClCioll<l1 COIl/('/'('II("(' IU/UR-77. 
 CATIONS WHERE THE RATE CHANGE FACTOR IS LARGE TYPICALLY  OR GREATER   A &)2 FILTER  IMPLEMENTATION MIGHT BE PROHIBITIVELY COSTLY DUE TO THE LARGE NUMBER OF FILTER TAPS THAT WOULD BE REQUIRED #)# FILTERS ARE A CLASS OF FILTERS INTRODUCED BY (OGENAUER   THAT PROVIDE A VERY EFFICIENT MEANS OF IMPLEMENTING THESE FILTER FUNCTIONS THAT DO NOT REQUIRE MULTIPLIERS %XCELLENT DESCRIPTIONS OF THIS CLASS OF FILTER ARE PROVIDED BY ,YONS  AND (ARRIS  WHICH FORM THE BASIS FOR THE FOLLOWING DISCUSSION &IGURE A SHOWS A SINGLE 
 r-^Kl>' it f———^^mm^—yl*\~mmm^—m—m+———*^-^ ~H OETKTOR r-*| TAPPED DELAY LINE | M 11 yNJ I *'' I FIG. 8.19 Block diagram of cell-averaging log-CFAR receiver. (Copyright 1972, IEEE; from Ref. 
 (15) The ﬁrst zero point is y/prime 1=ρa, so the following relationship must hold: y/prime 1cotα/sinθ−0.5ρe≥h. (16) Inserting (9) and (14) into (16), we have: y/prime 1=ρaBcosα≥λr/(2Nρa). (17) 4.3. 
 Early mission calibration and validation studies verified that the radar is performing  as intended. More on PALSAR appears later in this section.TABLE 18.3 Rsat-2 Modes  Mode Width W Access Resolution Looks 1/QSAR W QSAR Selective polarization km km m, Rg × Az Rg × Az Standard 100  250–750 25 × 26 1 × 4  162 0.62 Wide 150  250–650 30 × 26 1 × 4  195 0.77 Fine  50  525–750 8 × 8 1 × 1  64 0.78 ScanSAR Wide 500  250 –750 100 × 100 4 × 2 1250 0.40 ScanSAR Narrow 300  250–720 50 × 50 2 × 2  625 0.48 Single polarization Low incidence 170  125–300 40 × 26 1 × 4  260 0.65 High incidence  70 750–1000 18 × 26 1 × 4  117 0.60 Polarimetry Standard QuadPol  25  250–600 25 × 8 1 × 4  50 0.50 Fine QuadPol  25  400–600 9 × 8 1 × 1  72 0.35 Selective Single Pol Multi-look Fine  50  400–750 8 × 8 2 × 2  64 3.12 Ultra-Fine  20  400–550 3 × 3 1 × 1   9 2.2 Experimental MODEX (GMTI) Very High Resolution 3 × 1 1 × 1 ‡  Advanced Land Observation Satellite, JAXA, Japan. §  Discussed later in this section. 
 6 
 Lewis and D. H. Howard, “Security Device,” U.S. 
 Moreover, at frequencies above 6 GHz the frequency response is independent of angle,  so that D = 0. For lower frequencies, the frequency response is angle-dependent. For angles less than 20°, only two points were available, 0° and 10°, so separate  frequency regressions were run at each of these angles. 
 Again weareoverlooking the difference between adiscrete andacontinuous random process.. 40 THERADAR EQUATION [SEC. 2.10 taining thesignal. 
 ING VECTORS FOR NEAR 
 BASED BISTATIC RADAR v  )%% 0ROC     0T &   PP n  $ECEMBER   - ) 3KOLNIK  )NTRODUCTION TO 2ADAR 3YSTEMS  RD %D  .EW 9ORK -C'RAW 
 Ingeneral, thevideo sections will have abandwidth between 1and 3Me/see, with corresponding r-fand i-fbandwidths from 2to6Me/see, when normal search radar systems are used. Since therelay link isonly one section oftheover-all channel, the bandwidths ofitscomponents must besomewhat greater than would be necessary ifitalone were involved. Animportant decision isthechoice between amplitude and frequency modulation. 
 In addition, FFT estimates of mean velocity and spectrum width are biased by receiver noise. If the FFT approach is used, the bias due to noise can be removed by estimating the noise threshold in the spectral domain and truncating the derived spectrum.41 For most applications, the pulse-pair processor has become the technique of choice. However, in some research applications it remains advantageous to have access to the full doppler spectrum. 
 PROFILER RADARS THAT DETERMINE WIND SPEED AND DIRECTION AS A FUNCTION OF ALTITUDE  BY DETECTING THE VERY WEAK RADAR ECHO FROM THE CLEAR AIR ,OCATED AROUND AIRPORTS ARE THE 4ERMINAL $OPPLER 7EATHER 2ADAR 4$72  SYSTEMS THAT WARN OF DANGEROUS WIND SHEAR PRODUCED BY THE WEATHER EFFECT KNOWN AS THE  DOWNBURST  WHICH CAN ACCOMPANY SEVERE STORMS  4HERE IS USUALLY A SPECIALLY DESIGNED WEATHER AVOIDANCE RADAR IN THE NOSE OF SMALL AS WELL AS LARGE AIRCRAFT TO WARN OF DANGEROUS OR UNCOMFORTABLE WEATHER IN FLIGHT !NOTHER SUCCESSFUL REMOTE 
 Wismann, R. Romeiser, and W. Alpers, “Simultaneous measurements of the  ocean wave radar modulation transfer function at L, C and X bands from the research platform  Nordsee,” J. 
 -(Z BANDWIDTH WAVEFORM WITH    A    AND FD    4HE TIME SIDELOBE LEVELS ARE SEEN TO BE BELOW n D"  4HE AMBIGUITY FUNCTION IS SIMILAR TO THAT PROVIDED IN THE DISCUSSION OF .,&-   WHICH IS EXPANDED IN &IGURE  TO SHOW IN MORE DETAIL THE IMPACT OF DOPPLER SHIFT ON THE PULSE COMPRESSED WAVEFORM FOR PRACTICAL VALUES OF DOPPLER SHIFTS&)'52%    COSN ON PEDESTAL WEIGHTING FUNCTION SHOWN FOR N          &)'52%     
 This may berepeated ontheinner wall ofthepressure housing.. SEC. 11.11]DESIGN CONSIDERATIONS FORTHER-FHEAD 423 TypesojContainer.—If ther-fhead isnotpressurized, thesupporting framework forthe parts will bearectangular affair consonant with the standard construction practices used ontherest oftheradar. 
 27 of the French War Ministry in April 1918).  This particular ingenious application of the ‘lampes-  valves’ makes use of two resistance-coupled valves, back  . ‘IMPOSSIBLE’ CIRCUITS OI  to back. 
 400  Ii  I, I  I  I  .:u 300 I  I  I  I Figure 12.8 Contours or "radar  coverage" for radar height or 200 ft  above curved earth. (I) Geometrical  line-of-sight contour for k = J; (2)  constant-radar-signal contour in the  diffraction region, assuming a radar  capable or a free-space range of 220  nmi, vertical polarization, seawater,  k = i,f = 500 MHz; (3) same as (2),  but for 110 nmi free-space range;  (4) same as (2), but for 55 nmi free­ space range; (5) same as (2), but for -0 §  0  100 /  /  / I  6;1 5  / I I  I  o 1.....----l.----"-------'-----'------' 27.5 nmi free-space range; (6) contour o 1 o 20 30 40 50 defining start of diffraction region.  Range, nautical miles (Courtesy Proc. 
 LIKE GLINT ERROR  DISTRIBUTION IS OBSERVED 7ITH THE WIDER SEPARATION OF THE AIRCRAFT  THE TRACKING 
 Thomson, “Astromesh Deployable Reflectors for Ku and Ka-Band Satellites,” AIAA Symp .,  2002, pp. 1–4. 51. 
 Ref. 37, vol. II, pp. 
 Goodman and M. Silvestri, “Some effects of Fourier Domain Phase Quantization,” IBM J.  Res. 
 where dQ is the magnitude of the insertion phase ripple. The corresponding limit on improvement factor caused by amplifier amplitude instability is 7 = 20 log (dA/A) (5.3) where dA and A are the amplitude ripple and the magnitude of the amplitude volt- age, respectively. Time jitter of the RF output pulse envelope can also result from power supply ripple, as a result of Class-C operation of the module, and will also limit the MTI improvement factor. 
 Bannister, “The specification and measure - ment of radar performance,” IEE Int. Conf. Radar 2002 , Conf. 
 Frequency drift Magnetron ................Frequency change within pulse Modulator andmagnetron. Pulse length variation from pulse topulse Coherent oscillator. Detuning from intermedi- atefrequency Modulator .................Stability relative totrigger Delay lines ................Relative drift indelay timeXfaximum allowable value 20kc/secl 20kcjsecx 10Jfc/sec2 ~L1c/secZ (andprobably much more) 4y. 
 METEOROLOGICAL RADAR  19.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 Medhurst49 shows that α = 1 is a good assumption in many cases. The path loss  per mile for the three frequency bands of 4, 6, and 11 GHz is shown in Figure 19.1.  Lhermitte25 extends this early work to higher frequencies, confirming the relationship  and describing the effect of the drop-size distribution on the attenuation rate. 
 NIGHT CYCLE PRODUCES DRASTIC CHANGES IN THE ION 
 DOMAIN AMPLITUDE  WEIGHTING TO REDUCE THE FREQUENCY SIDELOBES  THE NONLINEAR 
 Lab. Rept. 9099, May 1988. 
 ERROR VALUES IN THIS REGION 4HE CURVES ARE CALCULATED MULTIPATH ERRORS BASED ON AN ASSUMED GAUSSIAN 
 P. King and T. T. 
 ING HIGHER LEVELS OF DATA EXCHANGE  PARTICULARLY TO AID 643 AND  SECURITY ACTIVITIES !N  IMPORTANT ADVANTAGE OF THE CHOSEN !)3 SOLUTION IS ITS RADIO FREQUENCY )T IS SUFFICIENTLY LOW SO THAT REASONABLE COMMUNICATIONS  ARE MAINTAINED IN SITUATIONS WHERE THERE IS NO  VISUAL OR RADAR LINE 
 de=element spacing M=number ofelements alongonedimension ofsquarearray Thephaseangleisassumed uniformly distributed. Equation (8.29)indicates anerrorof 0.22x10-4radian(-0.001°) foralOO-by-lOO-element uniformly illuminated arraywitha beamwidth ofapproximately 1°when (J=0.4.. Leichter's analysis1 ' of beam-poin ting errors was performed for a continuous line  source, but may be applied to a linear array. 
 95-99, March, 1952.  9. Wilkins, A. 
 LEVEL OBJECTIVE OF A RADAR DES 
 For example, if a radar’s clut - ter cancellation performance is driven by main-beam clutter residue due to platform  motion effects, the beam responses must span the radar’s main-beam and provide  degrees of freedom to allow for motion compensation in the array main-beam. In addi - tion, to cancel direction interference (jamming or casual EMI), the beam responses Tx Aper ture (1) Rx Aper ture (1) Shut OffTime Tx Aper ture (2) Rx Aper ture (2) Tx Aper ture (3) Rx Aper ture (3) Shut OffTransmit/Receiv e effective  phase centers aligned  across multiple PRIsVelocity Vector VT 2VT FIGURE 3. 26 Aperture control for platform motion compensation ch03.indd   28 12/15/07   6:03:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 How- ever, itisusually less troublesome tosuppress radio noise inavibrator supply than inasmall dynamotor. Vibrators can beobtained inhermetically sealed containers, making it possible todesign power supplies foroperation under extreme conditions ofaltitude and humidity. Production-type small vibrators are available with reed frequencies from about 100to115cps. 
 Fromm, “Measurements of bistatic  clutter cross section,” Environmental Research Institute of Michigan, Final Technical Report  RADC-TR-79-15, May 1979, AD-A071193. 100. P. 
 726, May 1981.) 35. Rihaczek, A. W.: "Principles of High-Resolution Radar," McGraw-Hill Book Com- pany, New York, 1969, chap. 
 Itcan bemounted with the control panel either vertical orhorizontal, aseach installation may demand. The indicator unit contains avideo amplifier, inaddition tothe cathode-ray tube and itsdeflection yoke and focus magnet. The synchronizer power supply provides the necessary voltages for theindicator and thesynchronizer. 
 There are at least two types of turbulent atmospheric  formations that can result in angel activity. One is the co,wective all or p/11me 1ha1 occurs in  the lower part of the atmosphere. The other is the atmospheric hori::011ta/ layer that can occur  at any altitude. 
 The radar in this case will be more sensitive to targets within  the duct than those outside it.  The extension of the radar range within the duct results in a reduction of coverage in  other directions. The regions with reduced coverage are called radar, or radio, holes. 
 Since in Radar techno l- ogy one, almost exclusively, directs the radiation, the power density at the range R increases with  the antenna gain GT:  € St=PT⋅GT 4πR2 (3.2)  The following can be considered: The transmitting antenna gain GT relates only to the maximum  of the antenna main lobe. Consequently, GT indicates the increase of the power density at a di s- tance R through Radar antennas based upon isotropic emitters with the same sending power. G  comprises the antenna losses and is calculated with the directivity D and the a ntenna efficiency η:  € G=η⋅D (3.3) . 
 750-10,000 .......Vibrator 400cps1@mOtOr-alter- nator Direct engine-driven lbalternator 400cps orhigher Direct engine-driven 3@alternator 400cps orhigher.41temate choice Dynamotor Dynamotor’ 400cps1dmotOr-alter- nator Forranges upto2300 watts, 400cps1+ motor-alternator Aircraft electrical systems today are normally 12-volt or24-volt direct current. Afew aircraft have 110-volt d-c supply. Ratings are nominal; a“24-volt” aircraft system usually supplies 27.5 +2.0volts. 
 D. Barter, K. L. 
 Tliere is also a general decrease of the refractivity gradients to the west. Off the  soutlicrn California coast. in (lie vicinity of San Diego, the boundary between moist and dry  air is relatively stable and exists at an average altitude of 300 to 500 meters. 
 The analogy of an optical lens is also found in radar. Three types of microwave  lenses applicable to radar are (1) dielectric lenses, (2) metal-plate lenses, and (3) lenses with  noni~nif~rm index of refraction.  Dielectric lenses. 
 !  AND AUDIO AMPLIFIERS MAY BE ALSO BE BIASED #LASS 
 4.3, but in this case, they ride on top of the clutter echoes.  Except for the inclusion of means to extract the doppler amplitude component, the noncoher-  ent MTI block diagram is similar to that of a conventional pulse radar.  The advantage of the noncoherent MTI is its simplicity; hence it is attractive for those  applications where space and weight are limited. 
 461-474, July, 1973.  60. Staelin, D. 
 An example will be treated. It will be convenient to write the radar equation (24.1) in decibels: SNR = Pav + Gt + Gr + X2 + T + RCS + Fp - (4-rr)3 - (R4 + L)-N Select 1000 nmi as the range. Then the frequency is 17.5 MHz (wavelength = 17.1 m and X2 = 25 dB), noise power = - 175 dB, and R4 + L = 261 dB. 
 PHASED ARRAY RADAR ANTENNAS  13.676x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 It uses 4-bit flux-driven nonreciprocal ferrite phase shifters and waveguide-type radia - tors at both apertures. The antenna is shown in Figure 13.48. It is mounted on a vehicle  and folds flat for transportation.FIGURE 13.47  Joint STARS antenna and aircraft ( Courtesy of Northrop Grumman Corporation ) FIGURE 13.48  PATRIOT multifunction phased array ( Courtesy  of Raytheon Company ) ch13.indd   67 12/17/07   2:41:15 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Moore, and A. K. Fung37) ch16.indd   37 12/19/07   4:56:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 PULSE BASIS AND THUS WILL CANCEL IN THE -4) CANCELER )T IS ASSUMED THAT THE RADAR SYSTEM IS FULLY COHERENT AS REQUIRED BY RULE  IN 3ECTION  4HE SECOND CAUSE OF PULSE COMPRESSION SIDELOBES IS SYSTEM INSTABILITIES  SUCH AS NOISE ON LOCAL OSCIL 
 This is opposite to the usual  optical refracting medium. A converging metal-plate lens is therefore thinner at the center than  at the edges, as opposed to a converging dielectric lens which is thinner at the edges. The  metal-plate lens shown in Fig. 
 This also serves tovary the current through the motor regu- lator field intheproper sense tomaintain constant speed. The motor is designed toobtain proper division offlux between the main field and the regulating field. The resistances ofthe regulating field and ofthe. 
 THE TASK AHEAD I29  camouflage. The enemy does not post convenient radar  beacons all along the route, but, of course, in civil  aviation the ustmost co-operation can be expected from  ground aids, and there is an entirely different prospect  for aids such as radar beacons.  Wartime necessity for the radar navigation of British  and Allied bombers at night over Germany brought  about the Gee system, perhaps in its day the most  extensively used of all radar non-echo navigational  systems. 
 #7 WAVE 
 M. B. Ringel, “Detection range analysis of an airborne medium PRF radar,” in IEEE 1981  NAECON Record,  Dayton, OH, 1981, pp. 
 (Ajier Greene and Lebenba~m,~' Microwave J.)  attenuated in passing through the atmosphere. The noise power available over a bandwidth B,  from the imaginary blackbody is kT, B,. The noise power after passing through the atmos-  phere is kT, B JL. 
 IOP Concise Physics Airborne Maritime Surveillance Radar, Volume 1 British ASV radars in WWII 1939–1945 Simon Watts Chapter 7 Comparative performance assessment 7.1 Introduction The previous chapters have described the metric ASV Mk. I, II and IIA, together with the centimetric ASV Mks III, IIIA, IIIB and IIIC and ASV Mk. VI, VIA, VI B and VI C. 
 •  However, must  consider vibration  during transport  (truck, airplane,  other?).•  Typically not a  major driver.•  Typically a major  driver.•  Typically a major  driver, driven by launch  vehicle (rocket).TABLE 12.3  Mechanical Design Drivers for Reflector Antenna Systems as a Function of Platform ch12.indd   36 12/17/07   2:31:58 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 
 EXCITERS AND SIGNAL PROCESSORS 4HE PRIMARY SURVEILLANCE RADAR OPERATES BETWEEN  AND  -(Z WITH A  
 Class B systems will  delay their own transmissions if slots are not available. (There is an additional option  of an SOTDMA-based Class B system.) Importantly, Class A and B systems receive  each others’ transmissions. The combination of AIS and radar-derived data gives benefits to navigation because  of the complementary nature of the two systems. 
 The possibility was investigated in October 1941 [13] but at that time it was concluded that there was no disadvantage to the use of ASV. However, by late 1942 it was apparent that there was a signi ﬁcant problem. A report published in April 1943 [ 14] analysed the results of 350 disappearing contacts taken from observations recorded in operators ’log books. 
   
 TRAL SPILLOVER FROM ADJACENT OR NEARBY BANDS )N THE 53 THE &## MANDATES A GAUSS 
 The last monopulse implementation illustrated (Fig. 20.5J) is termed phase- only monopulse. This processing is to be distinguished from the technique of phase interferometry, which has also been called by some authors36'37 phase- comparison monopulse. 
 The transition is matched bymeans ofthe.joatran.sformerl illustrated inFig. 9“23. The transmissi~n line contains ~he r-fs-titch inFig. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 processor designs as discussed in Section 2.9. 
 LIKE MODE BASED ON SQUINTED 3!2 )N   THE 5NIVERSITY OF )LLINOIS DEMONSTRATED THE 3!2 CONCEP T )N   DURING  A SUMMER STUDY THAT LAUNCHED A PROGRAM KNOWN AS 0ROJECT -ICHIGAN  IDEAS RELATED TO SYNTHETIC APERTURES WERE DISCUSSED BY , * #UTRONA OF THE 5NIVERSITY OF -ICHIGAN 7ILLOW 2UN ,ABORATORIES  # 7 3HERWIN OF THE 5NIVERSITY OF )LLINOIS  7 (AUSZ OF 'ENERAL %LECTRIC  AND * +OEHLER OF 0HILCO #ORPORATION  4HIS RESULTED IN A SUCCESSFUL  3!2 PROGRAM BY THE -ICHIGAN GROUP 4HE )LLINOIS GROUP ALSO DEMONSTRATED SUCCESS 
 Thelackofsmoothness ofthedataisdue,in part,tothefactthatthedatawasnotalltakenatthesametime.Foraparticular grazingangle thetwofrequencies hadtobeobtained byreflying theaircraftalongthesameflightpath. Different grazinganglesalsorequired reflying theaircraftoverthesamearea.Eachpointon thecurveisanaverage over1to2milesofgroundtrack. ThecurveofFig.13.10illustrates thebehavior oflandclutteratlowgrazingangles. 
 TO 
 The SNR is ﬁxed as 10 dB, and the pitch angle of antenna TR1 is ﬁxed as 0.05◦. Carry out Monte-Carlo simulation for 100 times to every sparsity sampling scheme, and calculate the MES estimated on the basis of height. Figure 8shows that application of the traditional approach fails to perform effective imaging of target given 80% under-sampling rate. 
 /Ê / .UMEROUS PROGRAMS TO GATHER SCATTERING COEFFICIENT DATA EXISTED PRIOR TO   BUT  SIZABLE DATA COLLECTIONS WITH ACCOMPANYING hGROUND TRUTHv WERE RARE 3INCE   HOWEVER  SEVERAL MAJOR PROGRAMS HAVE CHANGED THE SITUATION SO THAT MUCH INFORMATION IS NOW AVAILABLE )NDEED  THIS INFORMATION IS SO WIDESPREAD THAT AN ADEQUATE SUMMARY  OF THE LITERATURE IS IMPOSSIBLE (ENCE  THIS SECTION CAN ONLY GIVE HIGHLIGHTS OF THE  RESULTS AND MAJOR PROGRAMS 4HE READER SHOULD CONSULT THE THREE MAJOR COMPENDIA OF SUCH DATA FOR MORE INFORMATION BOTH ON RESULTS AND ON BIBLIOGRAPHY    NOTE THAT  INFORMATION IS SPREAD THROUGH MANY CHAPTERS OF THESE VOLUMES  3OME EARLY SCATTERING 
 It was found,46 for example, that  15 cm of dry powderlike snow had no effect on the measured backscatter over the frequency  range 1 to 8 GHz. Any backscatter contribution by the snow was completely dominated by  the contribution of the underlying soil. With 12 cm of wet snow, o0 decreased approximately 5  to 10 dB at grazing angles between 30 and 80". 
 12)  '5 T ~ = oo --~~- -·-·- 4 f (2nf )2  I S(J)/2 I I N;(J) 12 df  0 (11.14)  If the noise spectrum is a constant with spectral energy equal to NO watts/Hz of bandwidth,  the mean square error is  2 No ('5TR) = -a:,----~-- 4 f (2nf )2  I S(J) 12 df  0 (11.15)  An effective bandwidth p may be defined such that  a:, f (21tf)2 IS(J)l2 df 00  p2 = -00 00 = k f (2nf )2  I S(J) 12 df f IS(f)l2dfl -a:, (11.16)  -a:,  where E is the signal energy. This definition of bandwidth is unlike those discussed previously . EXTRACTION OF INFORMATION AND WAVEFORM DESIGN 405  in this hook and is not simply related to either the half-power bandwidth or the noise band­ width. 
 17 15 - 1729, December, 1976.  39. Shrader, W. 
 Farina, and M. D. Turley, “Spatial adaptive subspace detection in OTH radar,”  IEEE Trans ., vol. 
 K.: " Mathenlatical Tlteory of Optics " (mimeograplied lecture notes), pp. 2 12--213.  f3rown l lriiversity Graduate Scliool. 
 PLANE EFFECT /NE OPTION IS  TO INSTALL A BERM SHAPED LIKE AN INVERTED  6 RUNNING  BETWEEN THE RADAR AND THE TARGET 4HE PURPOSE OF THE BERMS SLANTED TOP IS TO DEFLECT THE GROUND 
 The separation Db between transmitter  and receiver is assumeq kn.9wn .. Equation (14.32} may he. written  S2 -Dl D =---- r 2(S -Db cos ljl.,) (14.33)  The above equation locates the target in the plane of the angle t/J, .. 
 Active-switch pulse modulators can be cathode p11lsers that  control the full power of the RF tube, mod-anode p11lsers that are required to switch at the full  hcam voltage of the RF tuhe but with little current, or grid pulsas that opcralc at a far smaller  voltage than that of the RF beam.  The chief functional difference between a hard-tube modulator and a line-type modulator  is that the switching device in the hard-tube modulator controls both the beginning and the  end of the pulse. In the line-type modulator, the switch controls only the beginning of the  pulse. 
 J. Doviak, and D. S. 
 It was found that 23% of aircraft needed attention after 10 days and 41% after 20 days. A change in crystal resistance occurred in 9 out of 10 cases in which sensitivity dropped and was constant in 10 out of 12 cases where the sensitivity remained constant. It was recommended that daily crystal checks be undertaken, with full sensitivity checks ateach minor inspection (presumably these occurred every few days) and whenever a TR box was changed. 
 The vertical gain ofthis latter antenna improved somewhat theratio ofsignal toinherent and to local noise, but didnot reduce interference appreciably since little inter- ference comes from high angles. Inatest ofa100-M c/sec relay equip- ment, the transmitting antenna was aquarter-wave vertical radiator mounted onthe skin ofanaircraft and acorresponding vertical quarter- wave receiving antenna was used atthe ground station. When alink was established ‘at800 to900 Me/see, itwas found very desirable toincrease the gain ofthetwo antennas inorder toextend the usable range oftheequipment. 
 It isimportant iftheelectromagnetic spectrum, considered asanaturalresource, istobeeffec­ tivelyandefficiently utilizedforthebenefitofall.Military radars,however, mustalsooperate inahostileenvironment wheretheymaybesubjected todeliberate interference designed to degrade theirperformance. Thevariousmethods forinterfering electronically withradararc calledelectronic COlll1temH'CISlIres, orECM. Aclil~eECMissometimes referred toas.iammillq. 
 When using an ultra-high speed platform, the azimuth bandwidth of the signal becomes large, and a very large PRF is required. The wide beam angle SAR increases the beam width and obtains echoes of targets from different angles. The wide beam SAR increase the imaging scope, but the two-dimensional spectrum is a sector. 
 The technique called on-axis  tracking,   described in Section 9.6, is a means of placing a computer in the tracking loop to  minimize lag and provide optimum angle-error filtering. Accurate system calibration also greatly reduces internal sources of error. Frequent  calibration corrects for drift in component gain and phase and pedestal flexure. 
 Although the technique of lobe rycognition is  reiativcly 'simple and has been reported to have been used in World War 11,'' ~ts poor  reliability, low target capacity, and poor accuracy, make it unattractive.  Timedifference height finding. The several height-finding techniques included in this section  were described in terms of a ground-based radar. 
 NOISE AMPLIFIER ,.!  AND  BANDPASS FILTER FOLLOWED BY A DOWNCONVERTER 4HE RADAR FREQUENCY IS DOWNCONVERTED  TO AN )&  WHERE FILTERS WITH SUITABLE BANDPASS CHARACTERISTICS  ARE PHYSICALLY REALIZ 
 The method of locating the target position is similar in either radar. Both require the  measurement of a distance and the angle of arrival in two orthogonal angular coordinates. The  distance measured by the histatic radar is the sum S = D, + D,, the total scattered path. 
  A   IS SUBSTITUTED FOR THE ANGLE OFF THE APERTURE NORMAL ! SPHERE OF RADIUS  A WILL ROLL OFF  D" AT  O  
 The bistatic radar can also use a  portion of the residual or uncancelled direct-path transmit signal as a reference in  a correlation  receiver , which cross-correlates the received and transmitted signals,  emulating matched filter operation.Chapter 23 ch23.indd   1 12/20/07   2:21:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 
 Lutz, and J. Vivekanandan, “S-Pol—NCAR’s polarimetric doppler research  radar,” in Proc. Int. 
 Thetransmitter noisethatenterstheradarreceiverviabackscatter fromtheclutteris sometimes calledtransmitted clutter.69Itcanappearatthesamefrequencies asthedoppler shiftsfrommovingtargetsandcanmaskdesiredtargetsorcausespurious responses. This extraneous noiseisproduced byionoscillations inthetube(usuallyaklystron amplifier) ratherthanbythethermalnoise,ornoisefigure.Whentheionoscillations appear,they usuallyhaveamagnitude about40dBbelowthecarrier,orelsetheyarenotmeasurable.69 Thusthereisnoneedtospecifyameasurement ofthisnoisetoalevelbetterthan40dBbelow thecarriertoinsuretherequired noiselevels.Sinceionoscillations mayoccuratsome combination oftubeparameters andnotatothers,theCWradartubeshouldbetestedfor noise-free operation overtheexpected rangeofbeamvoltage,heatervoltage,RFdrivelevel, andloadVSWR.Noise-free operation alsorequireswell-filtered beampower-supplies anda dcheatersupply. .. 
 Any use is subject to the Terms of Use as given at the website. Civil Marine Radar.  CIVIL MARINE RADAR  22.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 that the system is adversely affected if set up close to large radar-reflecting objects,  such as buildings, and so needs to be located ideally in relatively open spaces, similar  to that found on an antenna far-field test range. To enable tests to be more easily carried  out, direct injection of test targets and clutter into the RF path is feasible. 
 The distance traveled between pulses is generally less than  the antenna dimension so that the two antenna beams might be generated with two  overlapping reflector antennas or with a phased array divided into two overlapping  sub array^.^^ The effective separation between the antennas, Tpox, varies with the angle  6, as well as the aircraft velocity v. With reflector antennas, it is not convenient to change  the antenna physical separation to compensate for changes in 0, or o. The pulse repetition  period Tp might be varied to provide compensation, but this can introduce other complica-  tions into the radar design and the signal processing. 
 E. J. Barlow, “Doppler radar,” Proc. 
 ARRAY OUTPUT ADAPTIVE BEAM FORMING AND LOW SIDE  LOBE SUM AND DIFFERENCE BEAMS v  )%%% 3YMP ON 0HASED 
 Pap. , vol. 2,  no. 
 V !C  
 For multilook processing, the geometric resolution will  degrade as the number of looks increases and the speckle statistics of the intensity  image obey a gamma distribution, where the standard deviation decreases with the  square root of the number of independent looks.163 SAR images are useful for surveillance and reconnaissance applications. However,  jamming could make SAR images unusable. The use of ECCM is, therefore, essen - tial to reducing the vulnerability of SAR to jammers. 
 Pulse durations asshort as0.25 psec have been used successfully, particularly with high-frequency magnetrons whose starting times areshort. Tuning ofMagnetrons.-To change the frequency ofamagnetron more than afew megacycles per second requires that achange bemade inthe resonant circuits ofthe anode. Either the effective capacity or effective inductance must bevaried, and, since the resonant circuits are within theevacuated portion ofthetube, variation ofeither ofthem isa troublesome problem. 
 Vi- bration or power supply ripple can cause gain and phase modulation, particularly in RF amplifiers. Such modulation will degrade clutter attenuation unless the rip- ple frequency is a harmonic of the PRF. 3.8 LOGARITHMICDEVICES Characteristics Accuracy. 
 Horizon­ talpolarization mightbespecified whenenhanced rangecapability isdesiredandcomplete vertical coverage isnotnecessary. Thetheoretical curvesofFig.12.3assumeasmooth reflecting surface.Inpractice, thiscondition isseldommet,andthedifference inthecoverage diagrams obtained witheachofthetwotypesofpolarization isoftennotaspronounced as mightbeexpected onthebasisoftheoretical computations. Roughness ismoreimportant than theelectrical properties indetermining whether reflection isspecular ornot.Measurements haveshownthatthereflection coefficient forn~rmal(nonsmooth) groundterrainisinthe range0.2to0.4andisseldomgreaterthanO.S.atfrequencies above1500MHzexceptforlow anglesofincidence.2•3'" .'.•. 
 1.1 is shown as a power am- plifier, such as a klystron, traveling-wave tube, crossed-field amplifier, or solid- state device (Chap. 5). A power oscillator such as a magnetron also can be used as the transmitter; but the magnetron usually is of limited average power com- pared with power amplifiers, especially the klystron, which can produce much larger average power than can a magnetron and is more stable. 
 [ 42] obtained subsidence information from high-resolution X-band COSMO-SkyMed data (June 2013 to June 2014) with 2.21 m ×1.63 m (range ×azimuth) spatial resolution using PS pair InSAR method. Subsidence rates of most PS points in HK varied from −80 mm/yr to 40 mm/yr. Benattou et al. 
 IRE.) ofaO.84,t-diameter circularwaveguide isshowninFig.7.7.Ifonewishedtoobtainrelatively uniform illumination acrossaparaboloid aperture withafeedofthistype,onlyasmall angular portionoflhepatternshouldbeused.Anantenna withalargeratiooffocaldistance toantenna diameter wouldbenecessary toachievearelatively uniform illumination acrossthe aperture. Also.asignificant portionoftheenergyradiated bythefeedwouldnotintercept the paraboloid andwouldbelost.Thelost"spillover" energyresultsinalowering oftheoverall efficiency anddefeatsthepurpose oftheuniform illumination (maximum aperture efficiency). Ontheotherhand,iftheanglesubtended bytheparaboloid atthefocusislarge,moreof theradiationfromthefeedwillbeintercepted bythereflector. 
 This common path is an electrical conductor known as a WAVEGUIDE. A waveguide is hollow copper tubing, usually rectangular in cross section,having dimensions according to the wavelength or the carrier frequency, i.e.,the frequency of the oscillations within the transmitted pulse or echo. Because of this use of a common waveguide, an electronic switch, a TRANSMIT-RECEIVE (TR) TUBE capable of rapidly switching fromtransmit to receive functions, and vice versa, must be utilized to protect thereceiver from damage by thepotent energy generated by the transmitter. 
 QUENCIES IS LIMITED BY THE TIME IT TAKES FOR THE ELECTRONS TO TRANSIT FROM THE CATHODE TO THE ANODE OF THE TUBE 4HIS TRANSIT TIME MUST BE SMALL COMPARED TO THE PERIOD OF THE 2& SIGNAL TO BE AMPLIFIED 4O MINIMIZE THE UNDESIRED TRANSIT 
 R.: Radar Target Classification by Polarization Properties, Proc. IRE, vol. 48, pp. 
 MeteoroL, vol. 8, p. 424, 1951. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 A comparison between the gaussian and the exponential models on a linear scale,  as shown in Figure 2.14, indicates that the difference in spectral width at even very  low levels (–80 dB) is no more than about a factor of 2. 
    PP n  3EPTEMBER   ' 6 4RUNK  h2ANGE RESOLUTION OF TARGETS v  )%%% 4RANS  VOL !%3 
 5.Change from search tobeacon AFC. (Sec. 12.7.) 6.Stretching ofbeacon reply pulses inthe video amplifier. 
 It can usually be traded for  some more important characteristic.  7.2 ANTENNA RADIATION PATTERN AND APERTURE DISTRIBUTION  The electric-field intensity E(4) produced by the radiation emitted from the antenna is a  function ofthe amplitudeand the phase ofthecurrent distribution across the  aperture.'^'.^ E(4)  may be found by adding vectorially the contribution from the various current elements con- : 1 stituting the aperture. The mathematical summation of all the contributions from the current  elements contained within the aperture gives the field intensity in terms of an integral. 
 The target is at a height h, and at a distance R from the radar. Figure 12.1 illustrates  that energy radiated from the radar antenna arrives at the target via two separate paths. One is  the direct path from radar to the target; the other is the path reflected from the surface of the  earth. 
 TRACK DIRECTION  WHICH CAN BE EXERCISED IN A TWO 
    &$  &&!'&"$   $&   &  *!& % +$ !   ($  !!  $#  & &  % ($ 
 TRACK SURFACE SLOPE  COMPONENT "OTH OF THESE ADVANCED ALTIMETER MODES HAVE BEEN DEMONSTRATED WITH THE $0 AIRBORNE ALTIMETER  5NLIKE PREVIOUS RADAR ALTIMETER MISSIONS  #RYO3AT WILL DOWNLINK ALL ALTIMETRIC  DATA WITH ESSENTIALLY NO ONBOARD PROCESSING $ATA FROM EACH OF THE THREE MODES ARE . 
 WAVE PATHS OVER WHICH THE PLANE OF POLARIZATION CAN BE ROTATED BY THE %ARTHS MAGNETIC FIELD   THE CROSS SECTION IS MUCH SMALLER AND SHOWS THE CHARACTERISTIC FOURTH 
 P.: "Engineering Psychology in Radar," JPRS-55522, Joint Publications Research Service,  Washington, D.C., 23 March, 1972.  63. Trunk, G. 
 In the fast-wave device, however, the magnetic field determines the  frequency; but the frequency of a conventional slow-wave device is determined by  the circuit dimensions. An electron in an applied axial magnetic field Bo will rotate at  what is called the electron cyclotron frequency,  which is given by wc = eBo/mγ, where  e = electron charge, m = electron rest mass, and γ is the relativistic factor, which is   [1 + ( e/mc2)Vo], where c = velocity of light and Vo = beam voltage. The beam voltage  and the corresponding electron velocity in a gyrotron are high enough to cause relativ - istic effects. 
 £       WHERE THE  SK ARE THE COMPLEX IN 
 Furthermore, the batch processor requires less storage, detects better, and estimates angles more accurately than the binary integrator. For instance, if there were 80 pulses on target, one could batch 16 pulses, quantize this result to a O or a 1, and declare a target with a 3-out-of-5 (or 2-out-of-5) binary integrator. With an 8-bit analog-to-digital converter, the storage requirement per range cell is 17 bits (12 bits for the batch and 5 for the binary integrator) for the batch proces- sor as opposed to 80 bits for the binary integrator and 640 bits for the moving window. 
 Second, with certain detector tubes there issome “blackout effect”- that is,thesensitivity does notrecover immediately after thetransmitted pulse orafter other very strong signals. Third, care must beemployed int,he design ofthe power supply toreduce plate-supply ripple because such ripple isamplified bytheentire video amplifier. The detector has anoutput test point forconvenience inchecking thepass band. 
 beamwidth, sidelobes, and boresight error) of a metal space-  franie radome, assuming a uriiform or nearly uniform distribution of space-frame elements  over the surface of the radorne.lo4  Tl~c rrlhhcri7cd air-sr~pported radome is an example of a tllir~ wall radome in which the  tl~ick~lcsc of tl~c wrtll is ~11la1l coit~pu~ccl to a wnvclc~igtl~. A tl~i~i-wall radorlic c:111 itlso I,c  constructed of plastic with low dielectric constant and low loss tangent. This type of radonie  ;ipl1rc~.uir11;1tcs ;I tt~ir~ sl~cll wl~crc the loacis arid stresses are carried iri the sllell membrane itself. 
 Contours for fixed values of time delay are shown in Fig. 11.9b. The center contour corre­ sponding to TR = 0 is the spectrum of a rectangular pulse [Eq. 
 SIDERED !CCURATE  HIGH 
 Thishasbeencalleda parallel-li1Je configuration. Intheother,theproperlengthoflineismadeupoftheseries combination ofarelatively fewselected lengthsofline.Thisisaseries-li1Je, oracascaded, configuration. Although thediscrete natureofthedigitally switched phaseshiftermeansthat theexactvalueofrequired phaseshiftcannotbeachieved without aquantization error,the errorcanbemadeassmallasdesired. 
 TO 
 3, pp. 107–115, June 2005. 114. 
 MATCHING CIRCUITRY IN ORDER TO FUNCTION APPROPRIATELY IN AN AMPLIFIER (IGH PERFORMANCE TRANSISTORS AT HIGHER FREQUENCIES THAN 3 BAND ARE USUALLY BUILT USING COMPOUND SEMICONDCTORS 3UCH TRANSISTORS CAN RESULT IN HIGH CUTOFF FREQUENCIES AND DEMONSTRATE GAIN AT FREQUENCIES MUCH HIGHER THAN SILICON &OR EXAMPLE  ELECTRONS IN GALLIUM ARSENIDE 'A!S  TRAVEL APPROXIMATELY TWICE AS FAST AS THEY DO IN SILICON )T HAS A HIGHER SATURATED ELECTRON VELOCITY AND HIGHER ELECTRON MOBILITY  ALLOWING IT TO FUNC 
 Ship Safety. Radar is used for enhancing the safety of ship travel by warning of potential  collision with other ships, and for detecting navigation buoys, especially in poor visibility.  I11 terms of numbers, this is one of the larger applications of radar, but in terms of physical  size and cost it is one of the smallest. 
 Any use is subject to the Terms of Use as given at the website. Sea Clutter. 15.20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 At the other end of the potentially useful radar spectrum, in the millimeter-wave  band, the few published measurements of radar clutter lead to the conclusion that  millimeter-wave backscatter behaves in much the same manner as backscatter at the  lower microwave frequencies. This was suggested by the K-band curves shown in  Figure 15.5 for moderate wind speeds and further supported by some older shipboard  data at frequencies between 9 and 49 GHz.54 It should be noted that for maritime  radars clutter signal paths lie close to the sea surface, where the atmospheric and  water-vapor densities are highest. 
 Pulse Time vs  Frequency Characteristics   . 6  www.tektronix.com/radar   Pulse Modulation   While unmodulated  pulsed  radar are relatively simple to  implement, they have drawbacks . As described  previous ly,  unmodulated  pulses have relatively poor range  resolution . 
 Reducing the PRF reduces the number of intervening range-ambiguous clutter patches which fold into the target doppler cell, further improving SIC. To maximize range performance (not clutter-limited) average transmitter power must be the maximum practically achievable. Within the constraints of a tactical missile—small size, limited weight—this will tend to drive the design to higher-duty-cycle lower-peak-power systems. 
   -4) 2!$!2  Ó°ÈÎ .OTE THAT THIS DISCUSSION OF BINARY DETECTION IS ADDRESSED TO THE SPECTRAL DISTRIBUTION  OF REAL CLUTTER  THAT  WHEN VIEWED IN THE TIME DOMAIN BEFORE LIMITING  HAS A SMOOTHLY  VARYING CHANGE OF THE AMPLITUDE AND PHASE OF THE CLUTTER VECTOR  4HIS IS DISTINCT FROM  CLUTTER VARIATIONS DUE TO SYSTEM INSTABILITIES THAT ARE NOISE 
 Electronically steered phased array antennas (Chap. 7) are also used. The narrow, directive beam that is characteristic of most radar an- tennas not only concentrates the energy on target but also permits a measurement of the direction to the target. 
 CLUTTER IMPROVEMENT IS   )44 4 #3#2OPT OPT OPT OPT  WS S W WW  &    WHERE THE ASTERISK DENOTES COMPLEX CONJUGATION AND SUPERSCRIPT  4 IS THE TRANSPOSITION  OPERATOR  !N EXAMPLE WHERE THE OPTIMUM PERFORMANCE IS DETERMINED FOR THE CASE OF  CLUTTER AT ZERO DOPPLER HAVING A GAUSSIAN 
 For example, it is certainly true that a mechanically scanned reflector antenna cannot  switch a beam from one direction to another as fast as can a phased-array antenna. However,  it is seldom, if ever, that the operational requirements do not permit the system designer to  configure a system to do an equic:alent job with a mechanically scanned antahna.  An N-element array can, in principle, generate N independent beams. 
 The Heil tube is another form of velocity-modulated  radio-frequency oscillator. Electrons are emitted from a  cathode and pass through a grid on their way to the col-  lector, this grid playing no part in the creation of ultra-  high-frequency ocsillations, but controlling the total  current. The beam of electrons passes through two slots  in two concentric tubes placed at right angles to the  flow. 
 REFLECTION LOSSES IF THERE IS MORE THAN ONE HOP 4HE SHARP INCREASE IN  LOSS JUST BEFORE  NMI IS CAUSED BY TRANSITION FROM ONE TO TWO HOPS FOR TWO HOPS  THE LOSSY $ REGION IS TRANSITED TWICE AS MANY TIMES  GROUND 
 Moriyama, and T. Tadono, “PALSAR characterization and initial  calibration,” in Proceedings IEEE International Geoscience and Remote Sensing Symposium  IGARSS2006 , Denver, CO, IEEE, 2006. 24. 
 The SSG is probably the most cumbersome, since the suppression of the carrier and unwanted sidebands is seldom better than 20 dB and filtering must be employed to suppress these signals further. The balanced modulator is much simpler and sup- presses the carrier as well as the SSG. The filter needed for further carrier suppres- sion usually suppresses the unwanted sideband to the desired level without added poles. 
 QUALITY INSTALLATIONS  THE RIPPLE MAY BE OBJECTIONABLY LARGE 2OLLED 
 SCATTERING MODEL HAS  BEEN DEVELOPED BY %LKINS THIS CAN BE USED TO PREDICT TARGET OBSCURATION WHEN THE  TRANSMISSION PATH IS THROUGH THE AURORAL REGION 0ROVIDED THE RADAR IS WELL REMOVED FROM THE AURORAL ZONE  THE WAVEFORM CAN OFTEN BE CHOSEN SO AS TO MANIPULATE THE CLUT 
 When limiters prevent A/D saturation, the signals are limited in a controlled  manner that still enables good clutter rejection about 90% of the time. Rule 5.  Be wary of vibration and acoustic noise. 
 Pmc.Soc. Photo-Oplical IlIslrumen/alioll Ellgineers. vol.128,"Effective Utilization ofOptics inRadar Systems," pp.155-164. 
      
 159. 1311 274 ZHO. Jan. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°{ 4HE VERTICAL DIMENSION OF THE ANTENNA TOGETHER WITH RANGE  INCIDENCE  AND WAVE 
 FIELD AMPLIFIER #&!  THAT HAS BEEN USED IN SOME RADARS IN THE PAST  BUT IT ALSO SUFFERS LIMITATIONS FOR IMPORTANT RADAR APPLICATIONS  ESPECIALLY FOR THOSE REQUIR 
 PROPAGATION OF RADAR WAVES 463  maximum occurs when the antenna is directed along the horizon. The noise is greater along  the horizon than at the zenith since the antenna" sees" m.ore atmosphere. The antenna beams  must be oriented at elevation angles greater than about 5° to avoid excessive atmospheric­ ahsorption noise in the main beam. 
 Operation atthat frequency isalmostuselessforradarapplications withintheearth'satmosphere. Thesame 10mm lmm 01mm 10IJ.m 1fJom I I I J I 100 N 35GHz941402200 '"If)ClearatmosP"ere attenuation0NN::r:r<lgreaterthan30dB/kmin...'..Nt::>,,- ~1111thisregion , r<lII" "0CD "<.D" E10 -"Clear "- atmosphereen VIsible'tJ cregion .2Rain5mm/hr~~I '0 ::J C ~ 4 10. riain025mm/hr Figure14.15One-way attenuation ofelectromagnetic energypropagating intheclearatmosphere87 (oxygen andwatervaporat7.5gjm3,1atmosphere pressure, andabsolute temperature equal293K), rain88at293K,thetotalattenuation offogwithavisibility of300mandat293K(includes attenuation through aclearstandard atmosphere). 
 Buying radar range with transmitter power  alone can therefore be costly.  'l'llus tlierc alc Illany diverse rcquiren~et~ts and systelri constraints that enter illto tlie  selectior~ arid design of a transmitter. This chapter briefly reviews the various types of transmit-  tcr tu hcs atld their ct~aractcristics. 
 Tlie slim D, + D, locates the target somewhere on the surface of a prolate spheroid (an ellipse  rotated ahout its major axis) wliose two foci are at the location of the transmitter and receiver.  To further localize the target position the scattered-signal angle of arrival is required at  tlie receiver. The intersection of the ray defined by the angle of arrival and the surface of  tlle prolate splieroid dctcrnii~ics tl~ position of tlie target ill space. 
 3!2 IS A MODIFIED 3CAN3!2  MODE  IN WHICH THE ANTENNA PATTERN IS DRAGGED ALONG THE SURFACE AT A SLOWER RATE  THAN IN THE CONVENTIONAL STRIP 
 (a) ----------~ v Figure3.19(a)Aircraft withsingle dopplernavigation antenna beamatan angleytothehorizontal; (b)aircraft employing fourdoppler-navigation beamstoobtainvectorvelocity.. ('W AND I'REQIJENCY-MOI)IJI,ATED RADAR 93  frequericy is f, = 2(/,/c)v cos I-, wherc is the carrier frequency, v is the aircraft velocity, and c  is the velocity of propagation. Typically, the depression angle might be in the vicinity of 65 to  70". 
 795–809, 1996. 173. L. 
 27. Barton, D. K.: Historical Perspective on Radar, Microwave J., vol. 
 A generalized model of the main pulse with three microbursts with Gaussian envelopes registered in a particular frequency channel is presented in Figure 3. Figure 3. Main pulse with three microbursts measured in a particular frequency channel. 
 Burl, and W. W. Irving, “Optimal polarimetric processing for enhanced target  detection,” IEEE Transactions on Aerospace and Electronic Systems , vol. 
 (13.2) results in a spectrum of similar form, only with a ^-minus-4 asymptote. Phillips17 derived this asymptotic behavior on dimensional grounds, and a widely used simplification, obtained by replacing the smooth peak in Fig. 13.1 by a sharp cutoff, is generally referred to as the Phillips spectrum and in wavenumber space is written W(K) = 0.005//T4 K > g/U2 ni A. 
   2!$!2 #2/33 3%#4)/.   £{°Ç 4HE BEHAVIOR OF SHORT WIRE DIPOLES IS MARKEDLY DIFFERENT FROM THAT OF LONG DIELECTRIC  STRINGS !S SHOWN IN &IGURE   THE BROADSIDE ECHO OF A METAL WIRE EXHIBITS RESO 
 Lab. Memo. Rept. 
 61701012. National Natural Science Foundation of China (NSFC) under Grant No. 61671043 and Fundamental Research Funds for the Central University under Grant No.YWF-19-BJ-J-304. 
 Howard, I). D.: Predicting Target-Caused Errors in Radar Measurements, Electronic Warfare Defense  Elecrrotric.s, vol. 10. 
 LINE  CONSTANT 
 N. M. Greenblatt, J. 
 DWELL  !LERT HAS DETECTED .   05,3% $/00,%2 2!$!2   {°ÎÇ TARGETS  !LERT#ONFIRM PROVIDES THE RANGE MEASUREMENT OF CLASSIC (273 WAVEFORMS  WITHOUT THE FRAME TIME EXPENSE OF TRANSMITTING LINEAR &- RANGIN G DWELLS EVERY BEAM  POSITION 4HE #ONFIRM DWELL CAN ALSO BE USED TO CONTROL FALSE ALARMS  PERMITTING THE !LERT DWELL TO BE MORE SENSITIVE THAN CLASSIC 63 4HE !LERT PHASE IS USED TO SEARCH EACH BEAM POSITION OF THE FRAME FOR THE PRESENCE  OF A TARGET ! 63 WAVEFORM IS USED WITH A LOW DETECTION THRESHOLD AND A CORRESPONDING FALSE ALARM TIME ON THE ORDER OF A FEW SECONDS 4HE LOWER DETECTION THRESHOLD INCREASES SENSITIVITY 7HEN AN !LERT DWELL DECLARES A DETECTION  A #ONFIRM DWELL IS SCHEDULED FOR THAT !LERT DWELLS BEAM POSITION )F MONOPULSE MEASUREMENTS ARE AVAILABLE ON THE !LERT DETECTION  THE #ONFIRM BEAM CAN BE CENTERED ON THE DETECTION TO DECREASE BEAM 
 Radar grows and is viable since it satisfies important societal, economic, and military needs. It has no serious competitor for most of its many applications. The size of this edition of the handbook is smaller than the original edition. 
 PERPENDICULAR OR PERPENDICU 
 The large amount of range ambiguity  inherent in pulse doppler waveforms results in the possible eclipsing of target returns  ch04.indd   40 12/20/07   4:53:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 Tech. Rept.  NRL/MR/5325-93-7326, 1993. 
 This low value is necessary. however. if small general-aviation aircraft  are also to be detected. 
 DOWSv n WIDE 4HE PATTERNS ARE NOT SYMMETRICAL  ESPECIALLY AT THE HIGHER FREQUENCY .OTE THAT THE 2#3 CAN EXCEED  MI   D"SM &)'52%   -EASURED 2#3 PATTERN OF A " 
 TO 
 STATE AIR TRAFFIC CONTROL RADAR v )%%%  2ADAR #ONFERENCE  PP n   7 * #APUTI  *R  h3TRETCH ! TIME 
 Thus every piece of the connecting wire will act like a  portion of a transmitting line, and may radiate, with  consequent loss of energy. Normal transmission lines  between aerial and transmitter or receiver (as referred  to in Chapter III) cannot easily be used, so we employ  a long, hollow tube of metal as a conduit down which  the electromagnetic energy flows as in a pipe—or, rather,  one would like to t#ink as in a pipe: the actual direction  of flow of the energy in such a conduit is extremely  complicated, and is the object of much difference of  opinion among radar technicians. Conduits of this  nature are known as wave-guides, and their cross-  sectional dimensions are of the order of half a wave-  length, for mathematical reasons we need not explore  here. 
 A central element is excited, and all other elements are terminated. The pattern of this central element is the active element pattern. Diamond76 has examined the number of elements required in a small array to pro- vide a reasonable approximation to an element in an infinite array. 
 Theapproximately "ideal" feed-illuminations foramonopulse radarisshownin Fig.5.10.Thishasbeenapproximated insomeprecision tracking radarsbyafive-horn feed consisting ofonehorngenerating thesumpatternsurrounded byfourhornsgenerating the difference patterns. IOtherapproximations totheidealdesignsincludeatwelve-horn feed24 andafeedconsisting offourstacked hornsinoneplanewitheachhorngenerating three waveguide modesintheotherplane.2sHigher-order waveguide modesareusedtoobtainthe desiredsumanddifference patterns fromasinglehornwithout thenecessity ofcomplex () FRONT/~ fLEVATlON~ ~ OlfFERENCE SUM'1-~ AZIMUTH~ DIFFERENCEFigure5.10Approximately" ideal"feed-aperture illumi­ nationformonopulsesumanddifference channels. I. 
 78. Walther, C., C. Frush, and P. 
 In certain radar applications,  corrections must he made to the radar data to obtain a better estimate of elevation angle,  range, or height.19 Surface observations of refractivity often suffice for ascertaining the  effects of refraction.20-22  Refraction is troublesome primarily at low angles of elevation, especially at or near the  horizon. It can usually be neglected at angles greater than 3 to 5° in most radar applications.  Although more refined models of. 
 However, a quadrature splitter network, i.e., a power divider that provides a  3 dB split as well as a 90 ° phase offset, can be used to provide a constant impedance  at the input to the splitter regardless of the individual amplifier input impedances  (Figure 11.16). This ensures that a driver amplifier stage is presented with a well- matched load. Typical RF transmission media that are used in the construction of high-power  combiners include coaxial transmission lines, microstrip or stripline transmission  lines, or waveguide. 
   2%&,%#4/2 !.4%..!3   £Ó°{£ LAMINATES AND LOW 
 Each doppler channel consists of the single-bit / and Q correlators and the combiner, e.g., square root of the sum of the squares. After initial detection occurs, linear doppler processing may then be used to reduce the SNR loss. For example, the LO signal in Fig. 
 3 )NTERNATIONAL -ICROWAVE 3YMPOSIUM $IGEST    *UNE n    PP n  3 - 3HERMAN   -ONOPULSE 0RINCIPLES AND 4ECHNIQUES   .ORWOOD  -! !RTECH (OUSE  )NC    , % 0ELLON  h! DOUBLE .YQUIST DIGITAL PRODUCT DETECTOR FOR QUADRATURE SAMPLING v  )%%%  4RANSACTIONS ON 3IGNAL 0ROCESSING  VOL   ISSUE   PP n  *ULY   ' -INKLER   #&!2 4HE 0RINCIPLES OF !UTOMATIC 2ADAR $ETECTION IN #LUTTER  "ALTIMORE  -$  -AGELLAN "OOK #OMPANY    2 .ITZBERG   2ADAR 3IGNAL 0ROCESSING AND !DAPTIVE 3YSTEMS   #HAPTER   .ORWOOD  -! !RTECH  (OUSE  )NC    - 7EISS  h!NALYSIS OF SOME MODIFIED CELL 
 25-27, 1978, IEEE Publication 78 CH 1352-4 AES.  161. Ricardi, L. 
 202 ·21 l, 1958.  67. Brennan, L. 
 229 Filterbank: CWradar.76-77 digital.forMTI.121-125 Fixederror.FM-CW altimeter. 86-87 Flickernoise.74.347-348 Fluid-cooled helixTWT.207 Fluxdriveferrilephaseshifler.295 FM-CW radar.82-92 FMpulsecompresiion. 422-427 Foamshellradome. 
 1 Figure 13.13 illustrates the free-running multivibrator, which isa form ofrelaxation oscillator. Inorder tounderstand itsaction, assume aninitial condition (for example, atLOonthe waveform diagram) with thegrid ofV1beyond cutoff and that ofVzatcathode potential. Then V2istemporarily quiescent with itsplate atalow value; theplate ofV, isatB+, and grid g1isrising exponential ytoward bias potential asCl isdischarged through RI.Attime t,,glreaches thecutoff point and VI starts toamplify. 
 oneknownasaTR(transmit-receive) andtheotheranATR (anti-transmit-receive). TheTRprotects thereceiverduringtransmission andtheATRdirects theechosignaltothereceiver duringreception. Solid-state ferritecirculators andreceiver protectors withgas-plasma TRdevicesand/ordiodelimitersarealsoemployed asduplexers. 
 The echo power received by a radar from a target can  vary over a wide range of values, but we arbitrarily assume a “typical” echo signal  for illustrative purposes might have a power of perhaps 10−13 watts. If the radiated  power is 106 watts (one megawatt), the ratio of echo signal power from a target to the  radar transmitter power in this example is 10–19, or the received echo is 190 dB less  than the transmitted signal. That is quite a difference between the magnitude of the  transmitted signal and a detectable received echo signal. 
 In a speech delivered before the Institute of Radio  Engineers, he said :3  As was first shown by Hertz, electric waves can be completely reflected by conducting bodies. In  some of iny tests J have noticed the effects of reflection and detection or these waves by metallic  objects miles away.  It ~eems to me that it should be possible to design apparatus by means of which a ship could . 
 284 INTRODUCTION TO RADAR SYSTEMS  The half-power beamwidth is  B _ B _ B "' ~-~86A _  B -+ - ....., Nd cos 00 (8.13)  Therefore, when the beam is positioned an angle 00 otT broadside, the beamwidth in the plane  of scan increases as (cos Bot 1• The change in beam width with angle B0 as derived above is not  valid when the antenna beam is too far removed from broadside. It certainly does not apply  when the energy is radiated in the endfire direction.  Equation 8.13 applies for a uniform aperture· illumination. 
 C. (ed.): "MTI Radar," Artech House, Inc., Norwood, Mass., 1978. 7. 
  &)2 FILTERS LOW 
 It is our opinion that no single topic in radar meteorology has received more  attention than rainfall rate measurement. Although useful empirical expressions have  evolved and dual-polarization techniques show significant improvements in accu - racy, a completely satisfactory approach remains to be developed. Polarimetric measurements by the WSR-88D radars will allow more accurate  precipitation measurements and ice-water phase knowledge that is important for  making improved forecasts, separating winter precipitation into regions of rain and  snow, and detecting hazardous aircraft icing conditions.130 Implementation of phase- coding algorithms allow these radars to separate multiple time around (or multi - ple trip) echoes67,131,132 and to compute dealiased velocities in the range dealiased  echoes133; to classify and separate precipitation echoes from artifacts as ground clut - ter, sea clutter, and insects echoes72; to accommodate flexible scan strategies; and  to incorporate improved data resolution in range and azimuth. 
 If the sand  in the center is in too narrow a pile, the sand which remains might find itself in one or more  additional piles, perhaps as big as the one at the center.  The optimum waveform is one which has the desired ambiguity diagram for a given  amount of" sand " (energy). The usual pulse radar or the usi~al CW radar, as we shall see, does  not result in an ideal'diagram. 
 A number of operational and experimental HF systems  have accumulated their own noise databases and compared them with CCIR model  data; the report of Northey and Whitham gives a detailed analysis.109 An HF radar is generally designed to take advantage of what the environment per - mits; that is, the receiver noise figure should be good enough to make environmental  noise the limitation. An example of the CCIR Report 322 data will now be discussed. Figure 20.19  was drawn from Lucas and Harper.107 Noise power in a 1-Hz band relative to 1 W  (dBW) is given as a function of frequency for three different sources of noise: galactic,  atmospheric, and anthropogenic. 
 The measured MTI improvement  factor of the MTD on an ASR radar was about 45 dB, which represented a 20 dB increase over  the ASR 's conventional three-pulse MTI processor with a limiting IF amplifier. In addition,  the MTD achieves a narrower notch at zero velocity and at the blind speeds.  The processor is preceded by a large dynamic range receiver to avoid the reduction in  improvement factor caused by limiting (Sec. 
   
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 22.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 Class B systems to use only slots unallocated to Class A users. 
 Target and clutter powers are measured on a single pulse return and all target radial velocities are assumed equally likely." The SCV of two radars cannot necessarily be used to compare their performance while operating in the same environment, because the target-to-clutter ratio seen by each radar is proportional to the size of the radar resolution cell and may also be a function of frequency. Thus a radar with a 10-fjts pulse length and a 10° beamwidth would need 20 dB more subclutter visibility than a radar with a 1-JJLS pulse and a 1° beamwidth for equal performance in a specified clutter environment. The subclutter visibility of a radar, when expressed in decibels, is less than the improvement factor by the clutter visibility factor V00 (see definition below). 
 Urban infrastructure health monitoring with spaceborne aperture radar interferometry. Acta Geod. Cartogr. 
 AESA 
 The total range. i%C. 13121 RANGE ANDHEIGHT INDICES; SYNCHRONIZATION 523 tothecenter ofthesweep corresponds tothesum ofthetwo delays, but thefixed delay can beincluded inthecalibration. 
 AIR ! 
 FULLY 'AIN AND NOISE FIGURES ARE USUALLY TRADED OFF AGAINST REPEAT 
 The usual practice istochange thepulse lengths inversely with thepulse rate, thus keeping average power constant. But, because ofthe com- plications inherent inchanging pulse length byswitching pulse networks, the pulser designer isalways inclined tostick toone pulse width. If pulse rate must bechanged without acompensating change inpulse width, itisusually necessary tocontrol therectifier output byswitching pgwer transformer taps orbyvarying aseries primary impedance. 
 Eventhoughitmaybe arelatively simpleshapecompared totheothersmentioned aboveortothegeneralized nonplanarsurface. theproperties ofthecylindrical arrayarenotassuitable ingeneralasthose oftheplanararray.Inacylindrical array,theradiation patterncannotbeseparated intoan element factorandanarrayfactorasinplanararraytheory.Eachelement pointsinadifferent direction.Thuscomputations ofpatterns mustinclude bothelement andarraytogether. Another difficulty isthatthephaseaswellasthemagnitude oftheelement patternvaricswith position. 
 geometry  of tlie omset beam. Compensation might also be necessary for" range walk" which is the result  of the target " walking" through one or more range-resolution cells during the time osobserva-  tion. The achievable cross-range, or along-track, resolution worsens as the squint angle in-  creases from br.oadside (S,, 2 l/sin 0, where U = angle between aircraft heading and squinted  antenna beam direction). 
 (14.8) by 2 so that Eq. (14.10) becomes  R C  u < - <)., -4!1  Similarly, the right-hand side of Eq. (14.1 lh) is also reduced by a factor of 2. 
 TO 
 18-in. paraboloid; j= 5.67 in; 7000-ft cosecant-squared pattern Feed .............. .................Two-dipole type Gain ........... 
 MING  OR OTHER FUNCTIONS OVER A FREQUENCY RANGE COVERING SEVERAL DECADES  4HERE ARE  APERTURES DISTRIBUTED OVER THE AIRCRAFT THAT POINT FORWARD AND AFT  RIGHT AND LEFT  AS WELL AS UP AND DOWN 3OME APERTURES WILL BE SHARED FOR COMMUNICATIONS  RADIO NAVIGATION  AND IDENTIFICATION #.)  AS WELL AS IDENTIFICATION  FRIEND OR FOE )&&  DUE TO COMPATIBLE FREQUENCIES AND GEOMETRIES $ATA LINKS  SUCH AS *4)$3,INK  AN D ,INK  CAN SHARE  APERTURES WITH '03 AND , BAND SATELLITE COMMUNICATIONS , 3!4#/-  %7 APERTURES MUST BE BROADBAND BY NATURE AND CAN BE SHARED WITH RADAR WARNING RECEIVERS 272   RADAR AUXILIARIES  AND SOME TYPES OF #.)S &)'52%  -&!2 2& APERTURES SHARE LOW 
 A. Gray, and M. D. 
 TIVE STORMS v * !TMOS /CEAN 4ECHNOL   VOL   PP n    - "ROOK AND 0 +REHBIEL  h! FAST 
 2006 ,54, 4311–4322. [ CrossRef ] 29. Rubinstein, R.; Zibulevsky, M.; Elad, M. 
 COMPRESSION RADAR v  )2% 4RANS    VOL -), 
 Coaxial ma~ne'ron. ;\significant improvement inpower,efficiency, stability, andlireoverthe conventional magnetron isobtained whenthestrapsareremoved andthe7lmodeiscontrolled bycoupling alternate resonators toacavitysurrounding theanode.Thisisknownasacoaxial 11IOO"ctroll sincethestabilizing cavitysurrounds theconventional resonators. assketched in. 
 Frequency scanning may be accomplished from pulse to pulse by changing the transmitter and receiver frequency sequentially from one pulse to the next, or "within" the pulse, by transmitting a chirp linear-frequency- modulated (LFM) pulse or sequence of contiguous subpulses each stepped in fre- quency, and by processing each of a stack of receive beams in elevation each at one of the subpulse frequencies.17 The AN/SPS-39 S-band shipborne radar used a parabolic-cylinder reflector antenna fed by a line source to produce the change in phase with frequency necessary to scan its beam electronically in elevation. Up- graded with a planar array, this radar evolved into the AN/SPS-5218 (Fig. 20.26). 
 This definition does not include any doppler averaging across the individual  filters, and the definition does not provide a single figure of merit for a radar dop - pler processor because each filter may have different values of clutter attenuation  and coherent gain. Since each doppler filter has a coherent gain that is a function of target doppler, an  average value of signal-to-clutter improvement can be defined by averaging all filters  over its respective range of target dopplers:  If fCA G f df CA G f NC ff C f SCR=−⋅ ⋅ + ⋅ ∫ 1 00 0 1 1 01 , , ( ) ( ) 1 12 11 1f N C N fdf CA G f N∫⋅ + + ⋅− − −.............. ( ),f fN df ∫⋅             (2.21) The specific frequencies could logically be chosen as the crossover between indi - vidual doppler filters. 
 .4special system ofprecision bombing, known asthe “Oboe. sm.51] TYPES OF RADAR-BEACON SYSTEMS 247 system, ”involved simultaneous determination bytwo ground stations ofthe ranges ofabeacon-carrying aircraft with great accuracy. Coded signals forguiding the navigation ofthe plane were given bythe radar sets bysuitable modulation ofthe inter- rogating pulses. 
 G.: Weather Tracking with the AFCL Experimental 3-D Radar, AFCRL-70-0006. Air  Force Camhridge Research Lahoratories. Instrumentation Papers no. 
 ................................ ................................ .. 
 A normal short dipole antenna fed with a very short current impulse will radiate from  the feed points and the end of the element because of the latter’s discontinuity as far  as current flow is concerned. The current impulse will be reflected from the end of  the dipole and travel up and down the dipole causing a series of impulses of radia - tion. This extends the time signature of the radiated waveform and degrades the range  resolution of the system. 
 One wishes to use more pulses per CPI to enable the  use of better filters, but one also wishes to have as many CPIs as possible. Multiple  CPIs (at different PRFs and perhaps at different RF frequencies) improve detection  and can provide information for true radial velocity determination.30 The design of the individual filters in the doppler filter bank is a compromise between  the frequency sidelobe requirement and the degradation in the coherent integration gain  of the filter. The number of doppler filters required for a given length of the CPI must be  balanced between hardware complexity and the straddling loss at the crossover between  filters. 
 PUTED RADAR PROBABILITY OF DETECTION  PROPAGATION LOSS  OR PROPAGATION FACTOR  TO AN EXTER 
 In early radar the readout was a calibrated dial or display. In 3D radars, computers provide elaborate lookup tables to relate the ratios to the target elevation angle. The envelope-detected target returns in each of the beam positions are cor- rupted by thermal noise even in the most ideal of circumstances. 
 W. Attema, “The Dutch ROVE program,” IEEE Trans. ,  vol. 
 ORDER DOPPLER EFFECTS  THEN MIXES THE )& SIGNAL TO BASEBAND  AND DIGITAL SAMPLES ARE STORED FOR LATER PROCESSING !LTHOUGH AN ANALOG 
 TRIP TIME FROM THE RADAR TO A POINT R TO  ON THE SURFACE   R  TO    "X   S TO  #CTO  COSX      WITH " A COMPLICATED TRIGONOMETRIC FUNCTION OF GRAZING ANGLE  X   SURFACE SLOPE  S   AND TO 4HE FACTOR  " PEAKS AT POINTS OF SPECULAR REFLECTION  SO %Q  EXPRESSES THE  EFFECTS OF SPECULAR GLINTS AS WELL AS SHARP CURVATURES !LTHOUGH THE ORIGINAL THEORY  IS BASED ON A PHYSICAL OPTICS FORMULATION FOR A SCALAR FIELD SEE 3ANGSTON FOR THE  VECTOR FORM   SOME SUPPORT FOR ITS IMPLICATIONS CAN BE GAINED FROM A PLOT OF THE SQUARE OF SURFACE CURVATURE OVER A REAL SEA SURFACE &IGURE  A SHOWS THE  SURFACE SLOPE  MEASURED OVER A SHORT SEGMENT OF SURFACE IN THE 'ULF 3TREAM   WITH THE CORRESPOND 
 BASED AND TANGENT 
 The  radar computer’s resource manager must ensure that the maximum frame time is not  exceeded with the inclusion of these other functions during a search frame. For airborne pulse doppler radars, Autonomous Search can have two submodes:  Forward-aspect  and All-aspect Search . Forward-aspect Search is designed to detect  head-on engagement targets with high closing speeds that are not competing against  main-beam or sidelobe clutter. 
 The more filters used to cover the band, the less will be the maximum loss  experienced, but the greater the probability of false alarm.  A bank of narrowband filters may be used after the detector in the video of the simple CW  radar of Fig. 3.2 instead of in the IF. 
 RESOLUTION TWO 
 RANDOM 
 2016 ,52, 1559–1561. [CrossRef ] 23. Pieraccini, M.; Miccinesi, L. 
 MENTATIONS  AS LONG AS THE RECEIVE BEAM PRECISELY RETRACES ITS  SCAN PATTERN ON SUCCES 
 TH ELEMENTARY RADIATOR  DOES NOT BELONG TO THE J 
 Remote Sens. 2017 ,55, 4545–4557. [ CrossRef ] 25. 
 Although its performance may be good. it is difficult to  implement in practice because the 11 pulses must be rank-ordered to find the smallest and the  largest.  Although the median detector is superior to the mean detector (conventional receiver), it  is inferior to both the m-out-of-n detector and the logarithmic receiver when clutter can he  described by the log-normal28 or the' Weibull14 models. 
 51. Lewis, R. M.: Physical Optics Inverse Diffraction, IEEE Trans., vol. 
 35. Schneider, A.: Oversea Radar Propagation Within a Surface Duct, IEEE Truns., vol. AP-I 7,  pp. 
 Such an occurrence is called a false alarm. Therefore, if the threshold is set too  low. false target indications are obtained, but if it is set too high, targets might be missed. 
 Nonetheless, AESA performance is usually superior inside  FIGURE 5.9  Example AESA management comparison ( adapted 9 ) ch05.indd   9 12/17/07   1:26:41 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 
 The clutter phase varies from range cell to range cell owing to the distribution of the location of the scatterers in azimuth. Hence it is necessary to average the return for as long an interval as possible. Other processing features, such as phase comparison cancellation, were included in this radar (AN/APS-70). 
 THROUGH TO ACCEPTABLE LEVELS 4HE BISTATIC RADAR CAN ALSO USE A  PORTION OF THE RESIDUAL OR  UNCANCELLED DIRECT 
 TRANSPORT JITTER2EADING ERROR'RANULARITY ERROR6ARIATION IN OPTICAL PARALLAX   &ROM $ + "ARTON IN h-ODERN 2ADAR v 2 3 "ERKOWITZ ED   .EW 9ORK *OHN 7ILEY  3ONS    CHAP   P 4!",%    )NVENTORY OF !NGLE 
 -- 
 The search radar detects returns of widely dif - fering amplitudes, often so great that the dynamic range of a fixed-gain receiver will  be exceeded. Differences in return strength are caused by differences in radar cross  ch06.indd   22 12/17/07   2:03:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Barrick, “Near-grazing illumination and shadowing of rough surfaces,” Radio Sci ., vol. 30,  no. 3, pp. 
 SURFACE HEIGHT IS A FUNCTION OF MANY GEOPHYSICAL PARAMETERS  SUCH AS CURRENT FLOW  AN %L .I¶O EVENT  AND VARIATIONS IN THE OCEANS DEPTH 2ELATIVELY SMALL CHANGES ON THE ORDER OF CM  IN MEAN SEA 
 Vanderhill, J.V . Zolotarevsky, and T. Fariss, “Low illumination angle  bistatic sea clutter measurements at X-band,” in IEEE Int. 
 Current in one  clement will affect the phase and amplitude of the currents in neighboring elements. In a  planar array, the current at a particular element might be influenced significantly by a rela­ tively large number of its neighbors (perhaps from 20 to 100). Since the phases and amplitudes  of the currents at each of the elements change with the scan angle, the effects of mutual  coupling also change with scan angle and complicate the problem of computing and compen­ sating coupling effects. 
 10  It has been reported 11 that the -isolation between two X-band horn antennas of 22 dB  gain can be increased from a normal .value of 70 dB to about 120 dB by separating the two  with a smooth surface covered by a sheet of radar-absorbing material and providing screening  ridges at the edges of the horns. A common radome enclosing the two antennas should be  avoided since it limits the amount of isolation that can be achieved. CW AND FREQUENCY-MODULATED RADAR 73  The separate antennas of the AN/MPQ~46 CW tracker-illuminator of.the Hawk missile  system are shown in Fig. 
 way aswould asmall hillorridge. This type ofcontrast isless effective \vhcn thetarget isviefvcd from ahigher angle, forthesame reasons that make mountain contrast Icss effective athigh angles ofincidence. Natural structures also show radar contrast. 
 Furthermore the “corners” were atthe45°rather than the90°positions.. SEC. 13.17] RESOLVED-CURRENT PPI 541 practice because ofthe finite time forsweep “recovery.” Byusing a trapezoidal waveform, inorder that thetime spent atmaximum ‘‘nega- tive” current become appreciable, sweep duration can beincreased to about 60percent inpractice. 
 C. Wilson: A High-Resolution Rapid-Scan Antenna, J. Res. 
 OPPORTUNITY ARE OFTEN PRESENT AND CAPABLE OF SUPPORTING BISTATIC OPERATION IN THESE SMALL AREAS OF INTEREST     ! MULTISTATIC RADAR WITH ITS REQUIREMENT FOR COMMON SPATIAL COVERAGE NEARLY ALWAYS OPERATES IN THE CO 
 Theunambiguous rangeinthiscasecorresponds to ahalfwavelength atthedifference frequency. Thetransmitted waveform isassumed toconsistoftwocontinuous sinewavesof frequency IIand.l~separated byanamountI1fForconvenience, theamplitudes ofallsignals arcsetequaltounity.Thevoltagewaveforms ofthetwocomponents ofthetransmitted signal I'llandl'21maybewrittenas I'll=sin(2~(1t+4>d PH=sin(2n/2t+4>2)(3.18a) (3.18b) where4>Iand4>2arearbitrary (constant) phaseangles.Theechosignalisshiftedinfrequency bythedoppler effect.Theformofthedoppler-shifted signalsateachofthetwofrequenciesII and.l2maybewritten "IR=SIll [2n(f1±Iddt- 4n/~Ro+4>1] (3.l9a) "2R=Sill[2rr(f2±fll2)t-4n/~Ro+4>2] (3.19b) whereRo=rangetotargetataparticular timet=to(rangethatwouldbemeasured if targetwerenotmoving) .(."=doppler frequency shiftassociated withfrequency/1 .(.12=doppler frequency shiftassociated withfrequency /2. % INTRODUCTION TO RADAR SYSTEMS  Since the two RF frequencies f, and f2 are approximately the same (that is, f2 =/, + AS, where  Af 4 fl) the doppler frequency shifts fd, and fd2 are approximately equal to one another. 
 pp. 80-83, July-Aug., 1964.  32. 
 Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 94     The requirements of the measuring system for an as complete as possible description of the  scattering object result accordingly:   Broadband, if possible more than an octave ,  Coherent, for measuring a complex Radar cross -section σ   Measurement of the complex polarimetric RCS Matrix,   Variable aspect angle ( θ i, φ i, θ s, φ s)  Additionally, possibilities for the separation of disruptive influences, for calibrating the RCS Matrix as well as for acquiring the measurement data, must be available.  Present Radar sy s- tems inadequately fulfill these demands.   Since 1984 there has been a new generation of modern vector -network analyzers, conceived  for the measurement of microwave compone nts. 
 0 v sm ( 14.19)  where the symbols have been defined previously. As O decreases in the doppler beam­ sharpening mode. Tis made to increase. 
 BANDWIDTH PERFORMANCE AND A TOLERANCE TO A VARIABLE VOLTAGE STANDING 
 ESSARY TO AVOID CUTOFF &)'52%    !PPROXIMATELY IDEAL FEED 
 CHANNEL 3!2 IMAGING v   )%% 0ROC  PT &  VOL   NO   PP n  *UNE   0 % 0ACE  $ * &OUTS  3 %KESTROM  AND # +AROW  h$IGITAL FALSE TARGET IMAGE SYNTHESIZER FOR  COUNTERING )3!2 v )%% 0ROC  PT &  VOL   NO   PP n  /CTOBER   0 % 0ACE  $ * &OUTS  AND $ 0 :ULAICA  h$IGITAL IMAGE SYNTHESIZER !RE ENEMY SENSORS REALLY  SEEING WHATS THERE  v  )%%% !EROSPACE AND %LECTRONIC 3YSTEMS -AGAZINE  VOL   NO   PP n   &EBRUARY   , 3EVGI  ! 0ONSFORD  AND ( # #HAN  h!N INTEGRATED MARITIME SURVEILLANCE SYSTEM BASED ON  HIGH 
 A typical conical-scan rotation speed might be  30 r/s. The same motor that provides the conical-scan rotation of the antenna beam also drives  a tv.3-phase reference generator with two outputs 90" apart in phase. These two outputs serve  as a reference to extract the elevation and azimuth errors. 
 £Î°£n  2!$!2 (!.$"//+  FEWER ELEMENTS ARE REQUIRED )F THE TRIANGULAR LATTICE CONTAINS ELEMENTS AT  MDX  NDY    WHERE M   N IS EVEN  THE GRATING LOBES ARE LOCATED AT  COS COS COS COSAAL AALXS YS 
 (ILL  "OOK #OMPANY    #HAP   $ #ROSS  $ (OWARD  - ,IPKA  ! -AYS  AND % /RNSTEIN  h42!+8 ! DUAL 
 The am- plitude of the pulse is taken as the peak value. Dynamic-range considerations must take into account at least some three orders of magnitude for range varia- tion and three orders of magnitude for scan pattern variations. In practice, 60-dB instantaneous dynamic range sounds like a minimum value; in many applications it should be larger. 
 Nitzberg, Radar Signal Processing and Adaptive Systems , Norwood, MA: Artech House,  1999, pp. 199–202, 207–236, 267–290. 15. 
 3 )NTERNATIONAL -ICROWAVE 3YMPOSIUM  *UNE    PP n  4HOMAS +AZIOR PERSONAL COMMUNICATION   2AYTHEON 2& #OMPONENTS  !UGUST   9 7U AND 0 0ARIKH  h(IGH 
 I. Glaser, “Bistatic RCS of complex objects near forward scatter,” IEEE Trans ., vol. AES-21,  pp. 
 W. Ganz, and L. O. 
 Although a nominal 50-ohm load impedance may be assumed, the typical loading effect from the microwave power combiners and the circulator will produce variations in the load impedance presented to the transistor stage that may vary by ±50 percent from the nominal level. Depending on the phase of this mismatch, which can vary among adjacent devices, the port-to-port characteristics of an amplifier can vary dramatically. An important facet of Class-C design is that the response of the single-stage amplifier to these external perturbations must be addressed. 
 This reflector, shown in Figure 12.37, is used for an S-band meteorological  radar application.48 The panelized aluminum reflector is mechanically scanned via use  of a gimbal (not shown). The feed, a dual-polarized waveguide horn, is also shown in  Figure 12.37. The structural design of this large reflector was a significant task driven  by the need to maintain low reflector surface distortion (less than 50 mils) with severe  wind and gravity-loading forces and thermal gradients. 
  "  
 SAMPLE DELAY &)'52%    $IRECT DIGITAL DOWNCONVERTER  A  BASELINE IMPLEMENTATION   B  DECIMATING BEFORE FILTERS   AND C  INVERTING EVERY OTHER SAMPLE AFTER DECIMATION 
 ( Photograph courtesy of Raytheon Company ) ch11.indd   27 12/17/07   2:25:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 
 In the same manner single -beam, wide- beam,  spot- beam, and multi -beam are possible.  Because of modularity, transm itters of different sizes as  well as different number of elements can easily be configured baseband si gnals.  Control and  power supply lines are the only connections to each module. 
 D.: The NEXRAD Program—An Overview, Preprints, 20th Conf. Radar MeteoroL, pp. 757-761, American Meteorological Society, Boston, 1981. 
 King, and W. E. Kock: Microwave Antenna Measuretnents, Proc. 
 DELAY SCANNING IS INDEPENDENT OF FREQUENCY $ELAY LINES ARE USED INSTEAD OF PHASE SHIFTERS  AS SHOWN IN &IGURE B  PROVIDING AN INCREMENTAL DELAY FROM ELEMENT TO ELEMENT OF  S    SC  SIN P   WHERE C   VELOCITY OF PROPAGATION )NDIVIDUAL TIME 
 The threshold settings are a tradeoff between false alarms due to sidelobe returns and detectability loss in the main channel. An example is shown in Fig. 17.9 for a nonfluctuating target, where the ordinate is the probability of detection in the final output and the abscissa is the signal-to-noise ratio (SNR) in the main channel. 
 Either sort ofstabilization requires thevehicle tocarry gyroscopes orother devices which aresensi- tive todirection inspace and “know” the direction ofnorth orup. There are several ways ofmore orless completely mechanizing the stabilization ofthe beam. The most obvious and perhaps the most elegant istoprovide astable base forthescanner. 
 and Yu. B. Molochkov: "Proektirovanie Linzovykx, Skaniruyushchikx, Shirokodiapa­ zommykx Antenn i Fidernykx Ustroistv" (Design of Lenses, Scanning Antennas, Wideband  Antennas, and Transmission Lines.) Energiya, Moscow, 1973, pp. 
 ATED FROM A SURFACE 
 [ 53] measured the rate of subsidence using 36 sentinel-1A images (June 2015 and April 2017) with 5 m ×20 m (range ×azimuth) spatial resolution. The average deformation ranged from−127 mm/yr to 23 mm/yr and a new center of subsidence areas (Jiufengxiang) was found. In our study, four major areas of subsidence are clearly identiﬁed, namely, HK, QSIZ, NSL, and BSZ, which are consistent with earlier research conducted by Zhou et al. 
 86 PROPERTIES OF RADAR TARGETS [SEC. 311 Aswecan seefrom Fig. 3.15, this group ofscatterers will liewithin a patch ofsurface ofnearly rectangular shape, with itsarea approximately given by A=(Rci)(+cT secO). 
    
 Thisisprobably justified whenoperators arealert,motivated, andwelltrained.Itisalso justified whenautomatic (electronic) detections aremadewithout theaidofanoperator. Whentheoperator doesintroduce lossintothesystem,itisnoteasytoselectapropervalueto account forit.Thehelleractionistotakestepstocorrectlossinoperator performance rather thantolerate itbyincluding itasalossfactorintheradarequation. Fielddegradation. 
 D. A. Boutacoff, “Backscatter radar extends early warning times,” Defense Electronics ., vol. 
 -Ê  Ê " 
 MISS COUNT 'ENUINE TARGETS ARE RESOLVED IN RANGE AND DOPPLER  PRESENTED TO A DISPLAY AND USED FOR 473 CORRELATION AND TRACKING  &ALSE ALARMS ARE A CRITICAL ISSUE IN MOST RADAR MODES 4HESE ARE USUALLY SUPPRESSED  FOR THERMAL NOISE BY CONSTANT FALSE ALARM RATE THRESHOLDING  COINCIDENCE DETECTION  AND POST 
 SAR permits the attainment of high resolution by using the motion  oft he vehicle to generate the antenna aperture sequentially rather than simulta11eo11sly as with a  conventional array antenna. In this section, the radar may be thought of as carried by an  aircrart. but similar arguments apply for satellites or other moving vehicles. 
 Theklystron amplifier, in­ troduced toradarinthe19505,offeredthesystemdesigner higherpoweratmicrowaves than available fromthemagnetron. Beinganamplifier, theklystron permitted theuseofmore sophisticated waveforms thantheconventional rectangular pulsetrain.Theklystron was followed bythetraveling-wave tube,aclosecousinwithsimilarproperties totheklystron exceptforitswiderbandwidth. The19605sawtheavailability ofthecrossed-field amplifier, a tuberelatedtothemagnetron, Thereareseveralvariations ofcrossed-field amplifiers, each withitsspecialproperties; buttheyareallcharacterized bywidebandwidth, modestgain,and acompactness morelikethatofthemagnetron thantheklystronorthetraveling-wave tube. 
 Inparticular, thestrong ground clutter mentioned above was completely eliminated, targets being tracked regardless ofrange orposition. Allother known systems that have been developed tothe field-trial stage were tried atthis same site; none ofthem eliminated theground clutter. The only deficiency ofthis system, ashas been pointed out, isits inability tofunction properly when there areanumber oftargets inthe beam. 
 or other hydrometeors may be represented as a large number  of independent scatterers of cross section a1 located within the radar resolution cell. Let La;  denote the average total backscatter cross section of the particles per unit of volume. The  indicated summation of <T; is carried out over the unit volume. 
 The reason that these letter designations might  not be easy for the non-radar engineer to recognize is that they were originally selected  to describe the radar bands used in World War II. Secrecy was important at that time so  the letters selected to designate the various bands made it hard to guess the frequencies  to which they apply. Those who work around radar, however, seldom have a problem  with the usage of the radar letter bands. 
 Some ofthese, such astherocks, prefixed. Others, such asthebranches and leaves, move inthewind. InFig. 
 19.37  Signal Processing  ..............................................  19.37  Transmitter  ........................................................  19.38 Power  ................................................................ 
 153-155, January, 1974.  7. Benning, C., and D. 
 If we had to read this  distance in inches, centimetres, or any other fraction of  a standard measure we should need some way of trans-  lating this distance into true range.  In one type of coast-watching radar we do not bother  to estimate the physical distance between the blips  shown on the tube, but we move a control which shifts  a definite strobe spot along the trace until the spot  coincides with the echo blip on which we are taking a  reading. As this control is moved to regulate the posi-  tion of the strobe another circuit is simultaneously put  out of balance, and thus, entirely independently, can  give us a reading. 
 Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 12.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 OSU codes such as NEC-REF (OSU Reflector Code). The SATCOM Workbench is  available to members of the USA Satellite Industry Code Consortium.47 TICRA GRASP is a generalized PO-based code intended for both reflector system  design/analysis and scattering analyses. 
 However, most man-made targets are anisotropic. Therefore, anisotropy should be considered when the viewing angle is large. From another perspective, anisotropy is also a useful feature. 
 Aerosp. & Electron. Sys. 
 Rubin, W. L., and S. K. 
 (ed.): "Propagation of Short Radio Waves," MIT Radiation Laboratory Series, vol. 13,  McGraw-Hill Book Company, New York, 195 1.  17. 
 In the hybrid design, any imbalance or difference between the phase and amplitude of the voltages that are being combined is directed to a resistive termina- tion. The net result is that a constant load impedance is presented to the amplifier module under all conditions even when an adjacent module in a combining tier has failed. In a reactive combiner design, any imbalance in power or phase between two input signals results in reflected power and increased VSWR to the module driving it. 
  
 - 2#3 MEASUREMENTS MAY BE REQUIRED FOR ANY OF SEVERAL REASONS  RANGING FROM SCIENTIFIC INQUIRY TO VERIFICATION OF COMPLIANCE WITH PRODUCT SPECIFICATIONS 4HERE ARE NO FORMAL STANDARDS GOVERNING INSTRUMENTATION AND MEASUREMENT METHODS  BUT INFORMAL STAN 
 719 17.13 A100-Mc/sec Frequency-modulated Equipment. 721 17.14 Microwave System forPoint-to-point Service. 723 RA~AR RELAY SYSTEMS ......... 
 Inspecting Equation (16), we can ﬁnd that increasing the equivalent number of pulses at each CPI in one look direction may be e ﬀective to improve the cross-range resolution. In the following section, we will consider an alternative strategy to increase the sharpening ratio Kato improve the DBS imaging performance. 3. 
 1971 76.Thorp.J.S.:Optimal Tracking ofManeuvering Targets, IEEETrans.,vol.AES-9,pp.512-519, July, 1973 77Singer.R1\..andK.WBehnke: RealcTillle Tracking FilterEvaluation andSelection forTactical Applications. IEEET'·lIllS..vol.AF5-7.pp.100110,Jan.1971. 7R.Kallllan. 
 Lab. Rept. 4088, 1952. 
 The second gimbal system isheld parallel tothe plane ofthe gyro wheel, that is,horizontal, bymeans ofaservomechanism; and from this gimbal system two push-rods extend upward and provide roll and pitch inputs tothe mechanical computer located immediately over the gyro unit. The force tomove these rods isprovided bythe servomechanism rather than bythegyro itself. Inaddition toroll and pitch, timdesired angular position ofthe beam inspace isfedtothe co.{.puter asanother mechanical input provided byaservomechanism. 
  AIRPORT SURVEILLANCE  RADAR  WHEN THE THREE 
 P. Gogineni and K. Jezek, “Ultra-wideband radar measurements over bare and snow-covered  saline ice,” Proc. 
 However, with the proposed approach, accurate imaging of target can be performed. Figure 9shows that the height estimation performance of processing based on global sparsity is still superior to that of results obtained on the basis of independent processing under sparsity sampling condition. Even when the measurement quantity is low (10% of full data), the overall sparsity constraint can still ensure a better interferometric imaging performance. 
 (28) Here wehave used R=R’–; AR, (29) which istherange toapoint inthecenter ofthe“target area,”thearea shaded inFig. 3“15. - -Rainecho Without A14plate sweep: 33small div/mi With A/4 plate sweep &gain same as above Land targets Without 2/4 plate sweep: 9.5small div/mi Rain visible only atclose range With A/4 plate gain increased 6db Broad pipatcenter isartificial signal FIG.3.14.—A-scope observations ofrainandland targets. 
 30-33,  100-103, June, 1947.  63. Boyer, W. 
 VARYING SEA SURFACE GEOMETRY WITH MAJOR IMPLICATIONS FOR SHIP DETECTION AS DISCUSSED BELOW )T TRANSPIRES THAT A RELATIVELY SIMPLE MODEL ACCOUNTS FOR THE OBSERVED PROPERTIES OF  SEA CLUTTER WITH REMARKABLE FIDELITY  PROVIDED THE SEA IS NOT TOO ROUGH 4HIS MODEL IS BASED ON TWO ASSUMPTIONS  4HE SEA SURFACE CAN BE REPRESENTED TO A GOOD APPROXIMATION AS A SUPERPOSITION OR  SPECTRUM  3 FJ OF SURFACE GRAVITY WAVES SATISFYING THE DISPERSION RELATION   VJJ  GDTANH        WHERE  V IS THE WAVE ANGULAR FREQUENCY   G IS THE ACCELERATION DUE TO GRAVITY   J  IS  THE WAVE NUMBER OF THE WATER WAVE  AND  D IS THE WATER DEPTH &OR DEEP WATER  THIS  REDUCES TO   VJ G     FROM WHICH THE WATER WAVE PHASE VELOCITY CAN BE WRITTEN   VG,x § ©¨¶ ¸·V J P       WHERE , IS THE WAVELENGTH OF THE WATER WAVE  )N TERMS OF (& WAVELENGTHS  THE SEA SURFACE CAN BE REGARDED AS ONLY SLIGHTLY ROUGH   THEREFORE ADMITTING AN APPROXIMATE SOLUTION FOR THE SCATTERED F IELD IN THE FORM OF A  PERTURBATION SERIES EXPANSION IN THE PARAMETER  KA  WHERE  K IS THE RADIO WAVENUM 
 - !S SHOWN IN &IGURE   SCATTERING OBSTACLES ARE GENERALLY SORTED INTO THREE DIFFERENT  REGIMES BASED ON THEIR BODY SIZE IN WAVELENGTHS 6ERY LOOSELY  THESE THREE REGIONS ARE L 2AYLEIGH REGION TYPICAL BODY SIZE   K L 2ESONANCE REGION K   TYPICAL BODY SIZE   K L /PTICS REGION K   TYPICAL BODY SIZE 4HE BOUNDARIES SEPARATING THE THREE REGIMES ARE DIFFUSE AT BEST 4HE UTILITY OF OUR  2#3 ESTIMATION AND COMPUTATION METHODS DEPENDS IN LARGE MEASURE ON WHERE IN THIS SIZE SCHEME WE FIND OUR TARGET !LTHOUGH THE COMPLEXITY AND SIZE OF MOST SCATTERING OBJECTS PRECLUDE THE APPLICA 
 J Jamming, 5.27, 24.5 Jaumann absorber, 14. 36 to 14.37 J-ERS SAR, 18.9 Jet-engine modulation, 5.23 JianBing-5 SAR, 18.12 Jindalee OTH radar, 20.3, 20.22 performance model, 20.67 to 20.70 Joint STARS, 13.66 to 13.67, 17.23 to 17.24 JORN OTH, 20.12, 20.19 KK band, 1.17 Kalman filter, 7.28 to 7.35 Klystrode, 10.22 Klystron, 10.5 to 10.8, 10.26 origin of, 10.2 to 10.3 LL band, 1.16 Land clutter. See ground echo Laser radar, 1.18. 
   -%4%/2/,/')#!, 2!$!2   £°{Ç  * -C#ARTHY AND 2 3ERAFIN  h4HE MICROBURST HAZARD TO AVIATION v  7EATHERWISE  VOL     PP n    2 $ 2OBERTS AND * 7 7ILSON  h! PROPOSED MICROBURST NOWCASTING PROCEDURE USING SINGLE   DOPPLER RADAR v * !PPL -ETEOROL  VOL   PP n    + !YDIN  4 ! 3ELIGA  AND 6 "ALAJI  h2EMOTE SENSING OF HAIL WITH DUAL LINEAR POLARIZATION  RADAR v * #LIM !PPL -ETEOROL  VOL   PP n    ! * )LLINGWORTH  * 7 & 'ODDARD  AND 3 - #HERRY  h$ETECTION OF HAIL BY DUAL POLARIZATION  RADAR v .ATURE  VOL   PP n    2 - ,HERMITTE AND $ !TLAS  h0RECIPITATION MOTION BY PULSE DOPPLER RADAR v IN  TH 7EATHER  2ADAR #ONF  !-3  "OSTON    PP n  + ! "ROWNING AND 2 7EXLER  h! DETERMINATION OF KINEMATI C PROPERTIES OF A WIND FIELD USING  DOPPLER RADAR v * !PPL -ETEOROL  VOL   PP n    * $ 4UTTLE AND ' " &OOTE  h$ETERMINATION OF THE BOUNDARY LAYER AIRFLOW FROM A SINGLE DOPPLER  RADAR v * !TMOS /CEAN 4ECHNOL   VOL   PP n    * 7 7ILSON AND 7 % 3CHREIBER  h)NITIATION OF CONVECTIVE STORMS AT RADAR 
 TO 
  TO METER 
 References 1. Bao, Z.; Xing, M.; Wang, T. Radar Imaging T echnology ; Publishing House of Electronic Industy: Beijing, China, 2005. 
 VHF (30 to 300 MHz).  At the beginning of radar development in the 1930s,  radars were in this frequency band because these frequencies represented the frontier  of radio technology at that time. It is a good frequency for long range air surveillance  or detection of ballistic missiles. 
 Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 1.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 radars for the detection and tracking of satellites and ballistic missiles. At the upper  portion of this band there can be found long-range shipboard air-surveillance radars  and radars (called wind profilers ) that measure the speed and direction of the wind. 
 IZED RECEIVED SIGNALS AND  :DR IS EXPRESSED IN D"  WHEREAS  &H AND &V ARE THE MEASURED  PHASES OF THE SAME POLARIZED RECEIVED SIGNALS  +DP IS THE SUITABLY SMOOTHED RANGE  DERIVATIVE OF THE MEASURED DIFFERENTIAL PHASE   &DP  AND IS USUALLY EXPRESSED IN DEGKM  QHV IS THE CO 
   39.4(%4)# !0%2452% 2!$!2   £Ç°££ BECAUSE WE DEFINE ,/3 VELOCITY AS  D2DT  WHERE  2 IS THE RANGE TO THE TARGET 4HUS  A  POSITIVE D2DT CORRESPONDS TO A RECEDING TARGET AND RESULTS IN A NEGATIVE DOPPLER FRE 
 If supply voltage varies from itsnominal value, ranges indicated on the radar may be unreliable. Thisﬂuctuation usually happens only momentarily, however, and after a shortwait ranges normally are accurate. Frequency Drift Errors in ranging also can be caused by slight variations in the frequency of the oscillator used to divide the sweep (time base) into equal rangeintervals. 
 The development of the software can be an especially.,1-lemanding  task that cannot be considered minor.  8.10 OTHER ARRAY TOPICS  Hemispherical coverage.123 -125 A single planar phased-array antenna might typically provide  coverage of an angular sector ± 45° from the array normal; however, it is possible to achieve a  scan coverage of ± 60° or greater. The amount of scan depends on the loss of gain, the amount  of beam broadening, and the rise in sidelobes that can be tolerated. 
 Ifthis back-bombardment power exceeds the normal heater power ofthe cathode (which isfre- quently turned offwhile the magnetron isoscillating) abnormally short tube liferesults. Back bombardment usually limits the average power output. This limit can beraised bydesigning cathodes with very large thermal dissipation, but the average power ofmagnetrons designed for radar use rarely exceeds 0.2percent ofthe pulse power output. 
 ATION OF MICROWAVES BY RAIN AND DEDUCED  BY USING ,AWS AND 0ARSONSS DROP SIZE  DISTRIBUTIONS  THAT THIS ATTENUATION IN DECIBELS PER KILOMETER CAN BE APPROXIMATED BY   ++ 2 R D R2R ¯;  =A     WHERE +2   TOTAL ATTENUATION  D"      2R    RAINFALL RATE ALONG PATH  R  R   LENGTH OF PROPAGATION PATH  KM  +   CONSTANT DEPENDENT ON FREQUENCY AND TEMPERATURE  A   CONSTANT DEPENDENT ON FREQUENCY 4!",%    /NE 
 The clutter doppler  frequency will also be other than at dc if the radar is stationary and the clutter has a compo-  nent of velocity relative to tile radar, as when tlle clutter is due to rain storms, chaff, or birds.  Many of the AMTI tecliriiques described above can be applied to the stationary MTI radar  that must cope with moving clutter. Most conventional techniques fail, however, when both  stationary and moving clutter are within the same range resolution cell. 
 37, no. 7, July 1989. 33. 
 IRE, vol. 35, pp. 891-905, September, 1947. 
 VIEW ANDOR THE  REQUIREMENTS DICTATE FAST ELECTRONIC SCANNING OVER A SMALL &/6 AND SLOWER MECHANICAL SCANNING OVER A LARGER FIELD OF VIEW %3! 
 The amount of reduction is only 9.2 percent in covering a + 45 by + 45" "square" angular  region, and 7.7 percent for a +45 by +25 region. The smaller the angular region, the less the  saving. One caution in the use of triangular spacings is that, compared to square spacings, it is  more likely to produce high sidelobes in some portions of space. 
 AFAL-TR-73-296, April 1974. 42. E. 
 A performance margin is built in to the radar system to allow for  field degradation of the distributed array components between scheduled mainte - nance periods. Since array component failures induce only a gradual degradation,  maintenance can be performed on a planned basis. Online system sensitivity and  performance level is checked and displayed by the performance monitoring and fault  isolation (MFI) function.FIGURE 13.44  Ground-based radar system configurations ( Courtesy of Lockheed Martin Corporation ) AN/TPS-59  AN/FPS-117 AN/TPS-77 ch13.indd   64 12/17/07   2:41:09 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 LOWS THE ECHO 
 JAMMING RATIO APPROACHES UNITY IN WHICH CASE  THE CASCADE OF A SPATIAL AND A TEMPORAL ADAPTIVE PROCESSORS MAY PERFORM POORLY )N SUCH SITUATIONS  A JOINT TWO 
 The losses due to water layers on radomes have  been calculated by Blevis.116• 117  Theory predicts that a ~lh--Fain will produce a layer of water 0.142 mm thick on a  55-ft diameter radome. The theoretical loss through such a water layer is 1.5 dB at 4.2 GHz  and 4.4 dB at 9.36 GHz. Ruze118 confirmed Blevis's calculations and noted that a nonuni­ formly wet radome can cause significant phase perturbations in the aperture illumination, as  well as a transmission loss. 
 BASED REFLECTORS HAVE ALSO BEEN DEVELOPED BY THE (ARRIS #ORPO 
 LOBING TRACKING RADARS )T IS FOR THIS REASON THAT SUCH TRACKERS CANNOT BE USED IN MILITARY APPLICATIONS 4HE FUNDAMENTAL PROBLEM WITH THESE RADARS IS THAT ANGLE TRACKING IS ACCOMPLISHED BY DEMODULATING THE AMPLITUDE MODULATION IMPOSED ON THE TARGET RETURN PULSES OVER A COMPLETE SCANNING OR LOBING CYCLE 4O JAM THIS TYPE OF RADAR EFFECTIVELY  THE RADARS ANGLE 
 As in a pulse radar, a CW radar that uses a rapid rate of frequency modula- tion, in order to sample the doppler, must have this rate twice the highest ex- pected doppler frequency if an unambiguous reading is to be obtained. If the rate falls below the doppler frequency itself, there are problems of blind speeds as well as ambiguities. (A blind speed is defined as a relative velocity that renders a target invisible.) This will be discussed in more detail in Sec. 
 Solid-state microwave devices for radar generally operate Class-C, which is self-pulsing as the RF drive is turned on and off. 5. Graceful degradation of system performance occurs when modules fail. 
 The ASAR alter - nating polarization mode provides dual-polarized images that are similar to those that  have been available from many airborne systems for decades, although not available  from an SBR (except for SIR-B and SIR-C) until ENVISAT. PALSAR.  In contrast to the incoherent polarimetric options of ASAR, the Phased- Array L-band Synthetic Aperture Radar (PALSAR) aboard Japan’s ALOS‡ (launched  in January 2006) includes full quadrature§ polarimetry.22,23 The PALSAR modes  include standard single-polarization mapping modes, a ScanSAR mode, a variety of  dual- and quadrature-polarized modes, and experimental modes, including SpotSAR. 
 M. R. Keller, B. 
 An adaptive ship detection scheme for Spaceborne SAR imagery. Sensors 2016 ,16, 1345. [ CrossRef ][PubMed ] ©2019 by the authors. 
 (When comparing the CFA with the linear-beam tube, the  entire transmitter system needs to be compared and not just the tube itself.) The CFA  has also been considered as a means to boost the power output of previously existing  radar systems that employed magnetrons. There have been both backward-wave and  forward wave CFAs. The backward-wave CFA is also known as the Amplitron . 
 Atransversal filterwiththreedelaylineswhoseweightsare1,-3, 3,- 1givesasin3nfdT response. Thisisafour-pulse·canceler. Itsresponse ise~uivalent toatriplecancelerconsisting ofacascadeofthreesingle-delay-line cancelers. 
 -ro ( 10.16)  The output y0(t) of a filter with impulse response h(t) when the input is Yin(t) = s(t) + n(t) is  00  Yo(t) = J Yin(l)h(t -A.) dA.  -00  If the filter is a matched filter, then h(11.) = s(t1 -,l) and Eq. (10.17) becomes  Yo(t) = J 00  Y1n(A.)s(t 1 -t + ,l) d). 
 For small footprints the scatter var- ies over a wide range, and system designers must account for this. 72.7 SCATTERINGCOEFFICIENTDATA Numerous programs to gather scattering coefficient data existed prior to 1972, but sizable data collections with accompanying "ground truth" were rare. Since 1972, however, several major programs have changed the situation so that much information is now available. 
 Gossard. E. E., and W. 
 NENTS OF AN IMPULSE TO BE RADIATED AT DIFFERENT TIMES  HENCE DISPERSING THE IMPULSE )F SUCH ANTENNAS ARE USED WITH TIME 
 The ionospheric sounding mode of MARSIS is a special case,  elaborated below. Subsurface Sounding –flight Systems.  Subsurface sounding from a space- based radar is considerably more challenging than from a surface-mounted GPR  (Chapter 21) or a very low altitude aircraft. 
 MODAL DISTRIBUTIONS CAN BE USED AS PRIOR AND REALIZED AS POSTERIOR DISTRIBUTIONS (OWEVER  PARTICLE FILTERS REQUIRE QUITE A BIT OF COMPUTATION 4HE UNSCENTED +ALMAN FILTER  MORE EFFICIENTLY CALCULATES THE TRACKING ACCURACY BY  PROPAGATING SELECTED CARDINAL POINTS THROUGH THE FILTER 4HE UNSCENTED +ALMAN &ILTER APPROXIMATES THE COVARIANCE MATRIX WITH A SET OF  ,    SAMPLE POINTS  WHERE  , IS THE  NUMBER OF STATE DIMENSIONS 4HE SAMPLE POINTS ARE PROPAGATED THROUGH AN ARBITRARY TRANSFORM FUNCTION AND THEN USED TO RECONSTRUCT A GAUSSIAN COVARIANCE MATRIX 4HIS TECHNIQUE HAS THE ADVANTAGE OF REPRESENTING THE COVARIANCE ACCURATELY TO THE THIRD ORDER OF A 4AYLOR SERIES EXPANSION !S A RESULT  THE CALCULATED TRACKING ACCURACY IS AT LEAST TO THIRD ORDER  UNCONTAMINATED OR hUNSCENTEDv  BY THE NONLINEARITY !DAPTING &ILTER TO $EAL WITH #HANGES IN 4ARGET -OTION  4HE +ALMAN FILTER  ASSUMES LINEAR TARGET MOTION PERTURBED BY A RANDOM MANEUVER MODEL AS A MATHEMATI 
 Even though the bandwidth ofthese channels islarge, itmay still benecessary tomake anapproximate compensation fortwo types of unbalance. The smaller gain intheundelayed channel would ordinarily result inagreater bandwidth. This channel should therefore benar- rowed tomatch the other bythe addition ofcapacity toground inthe low-level stages. 
 FALSE 
 It also took important  advantage of advances in digital receivers and digital processing that occurred since the  development of the ASR-9 to significantly improve what could be accomplished with  this radar.55 As mentioned, solid-state transmitters require the use of long pulses. The  ASR-12 employed a 55 µs pulse duration at a peak power of 21 kW. This means that  targets out to a range of about 5 nmi would be masked, or eclipsed, by the long pulse  and might not be detected. 
 For  the CASH- CFAR, a special maximum -minimum circuit is applied. Using this variant, the “A”  sum- values are first halved by a special efficient pair -wise maximum calculation. Then (using  α/L an d or β/L the threshold value results as the smallest of the remaining sum -values. 
 CELL PROBABIL 
 while the unwanted signals are shown by the broken arrows. The unwanted  signals ir~clude:  I. The reflection of tlie transmitted signals at the antenna caused by impedance mismatch. 
 The target trails that used  to be provided by the designed-in persistence of original radar monochrome CRTs  have to be provided electronically. The trail length is required to be user selectable in  units of time. When True Motion is selected, trails can be chosen by the operator to  be shown in either true or ship-relative reference frames. 
 E. Baldwin, and W. D. 
 This is a small uninhabited island situated 7 nmi off the west coast of Wales. It is a bare rock with an area of about 10 ha, about 300 m by 300 m in extent and with a highest elevation of 42 m (138 ft). Its radar response was similarfor all directions and its radar cross section (RCS) was suf ﬁciently large for radar returns not to be affected by local sea conditions. 
 ODICALLY 4HE EFFECT ON THE GAIN AND RADIATION PATTERN OF RANDOM ERRORS IN THE ANTENNA EXCITATION FUNCTION IS DISCUSSED IN 3ECTION  0HASE  1UANTIZATION  0HASE SHIFTERS SUITABLE FOR STEERING PHASED ARRAYS ARE  DESCRIBED IN 3ECTION  -OST OF THESE PHASE SHIFTERS ARE DIGITALLY CONTROLLED AND CAN BE SET WITH AN ACCURACY THAT IS A FUNCTION OF THE NUMBER OF BITS ! SMALL NUMBER OF BITS IS DESIRED FOR SIMPLICITY OF PHASE 
 Thelaserradarcanemploytheequivalent ofeitherthemicrowave videoreceiverorthe superheterodyne receiver. Theformeriscalledanincoherent (envelope) receiver ordirect photodctection. Thelatteriscalledacoherent (heterodyne) receiverorphotomixer. 
 Approach Channel Ball 1 Ball 2 Ball 3 Ball 4 Ball 5 Initial Traditional approach–( −0.20,−0.20) (0.20, −0.20) (0.00, 0.00) ( −0.20, 0.20) (0.20, 0.20) 1( −0.20,−0.20) (0.19, −0.19) ( −0.04, 0.01) ( −0.22, 0.19) ( −0.14, 0.20) 2( −0.21,−0.20) (0.18, −0.19) ( −0.04, 0.00) ( −0.20, 0.17) (Null, Null) Proposed approach1( −0.20,−0.20) (0.19, −0.19) ( −0.01, 0.01) ( −0.20, 0.19) (0.20, 0.21) 2( −0.20,−0.20) (0.19, −0.19) ( −0.01, 0.01) ( −0.20, 0.19) (0.20, 0.21) One of the practical applications of the proposed approach is security check. Here we conduct detecting and imaging on closed chamber in the anechoic chamber. The chamber is used to simulate luggage carrier, which is placed with one knife, two bottles of water (one is full and the other is half-full) and two bottles of Coco-cola. 
 Remote Sens. 2015 ,36, 4550–4569. [ CrossRef ] 2. 
 Since solid-state transmitters are covered in Chap. 5, we will limit this chapter to discussions of RF tubes for radar systems, as described in the next section. 4.4 RFAMPLIFIERTUBES Until the mid-1970s, radar transmitters used only vacuum tubes of one kind or another for microwave power generation. 
 Also, the signal-to- noise ratio required for detection, ( S/N)req = E/No when Bt  ≈ 1, where B is the receiver  bandwidth and t  is the pulse width. The signal processing time, to, is sometimes set by the amount of doppler spread - ing or velocity-walk, ∆fd generated by a moving target. Specifically, ∆fd = (to)−1 = Bn,  ch23.indd   5 12/20/07   2:21:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Variable Condensers. -Certain types ofrapid scanners (see Sees. 9“14 to916) operate insuch away that, asadriving shaft rotates con- ,. 
 It is also possible to obtain weak echoes from a deep, intense fog at millimeter.  wavelengths, but at wavelengths of 3 cm and longer, echoes due to fog may generally be  regarded as insignificant.  Attenuation by precipitation. 
 CM RADIATION IS APPROXIMATELY  OF THE VALUE THAT WOULD BE SCATTERED BY AN ALL 
 Figure 3.16 shows a plot of  several of the Bessel functions. The argument D of the Bessel function is proportional to range.  The Jo amplitude applies maximum response to signals at zero range in a radar that extracts  the d-c doppler-frequency component. 
 K. Raney, “Hybrid-polarity SAR architecture,” in Proceedings IEEE Geoscience and  Remote Sensing Symposium , Denver, CO, IEEE, 2006. 112. 
 It can  occur in displays which collapse the range information, such as the C-scope which displays  elevation vs. azimuth angle. The echo signal from a particular range interval must compete in a  collapsed-range C-scope display, not only with the noise energy contained within that range  interval, but with the noise energy from all other range intervals at the same elevation and  azimuth. 
 Fortunately, the minima of the curves (Fig. 2.2) are very broad and flat, and therefore the exact value of a does not make much difference for the usual range of values of .BnT. The interpretation of CB as a factor that accounts only for nonoptimum width of the predetection filter is permissible for simple pulse shapes and approximate results, but in principle it must also account for the complete amplitude-phase characteristic of the filter: its departure from a matched-filter characteristic. 
 If n pulses are summed in an  ideal integration, then the S/N ratio at the output of the integrator improves by a factor n.  This  practically cannot be ac hieved by incoherent integration, since additional noise develops when  rectifying.  The improvement, which can be achieved by an operator with a storage tube, is  approximately proportional to  € n. 
 25.) mean and the variance, and a threshold of the form T = jx + Kv is used. Though the mean is easily obtained in hardware, the usual estimate of the standard devi- ation a = \±2(Xi - JC)2] 2 (8.18) where x = jj**' (8'19)CELL AVERAGE CFAR RATIO DETECTORS LOG INTEGRATOR BINARYINTEGRATORNOJAMMINGPROBABILITYOF DETECTION PROBABILITY OF DETECTION NO JAMMING PFA "O"6 . S/N (dB) FIG. 
 FREQUENCY CUTOFF TO LOWER FREQUENCIES ALONG THE HIGH 
 KM SWATH  TO  
 It is the frequency where one can find long-range precision instrumentation radars used for the accurate tracking of missiles. This frequency band has also been used for multifunction phased array air defense radars and for medium-range weather radars. X Band (8 to 12.5 GHz). 
 R.: Radar Target Classification by Polarization Properties, Proc. I RE, vol. 48, pp. 
 Thereflected energytherefore willhaveapolarization perpendicular tothewiresoftheparabolic reflector andwillpass through withnegligible attenuation. Thetwistreflector canbemaderelatively broadband. An attractive featureofthisantenna configuration isthatthebeamcanbereadilyscanned overa wideanglebymechanical motionofthelowinertiaplanarreflector. 
 9.14, 9.15, and 9.16). Itisassumed that sin0=dand. l-ruuLr A/vvL II Trigger Delaycircuit Fhp-flopSawtooth Phase generatorAmphfler..sphtfer I I T W+--- .F—.LFlipflop T /;T_ I I Oscillator% — b T=Scanperiod 7 —— FIG. 
 SQUARED  AND A GENERIC HEIGHT 
 Walton, E. K., and J. D. 
 9.28) mounted onthe same pedestal and rotating together inazimuth at4 rpm. The other antenna isused for long-range search and azimuth IC.V.Robinson, “Tbe SCI Rapid Scan Heigh&6nding Antenna,” RLReport No.6S8. SEC. 
 FEED SYSTEM PROVIDES THE PROPER  APERTURE ILLUMINATION 4HE LENS HAS INPUT AND OUTPUT RADIATORS  COUPLED BY PHASE SHIFT 
 FREQUENCY AMPLITUDE NOISE  BECAUSE THE TARGET CONTROLS THE PERIODICITY OF THE MODULATION  WHICH IS DEPENDENT ONLY ON THE AIRCRAFT PROPELLER ROTATION RATE AND NUMBER OF BLADES *ET AIRCRAFT MAY ALSO CAUSE ECHO AMPLITUDE MODULATION OF RADAR SIGNALS REFLECTED FROM ROTATING FAN BLADES FROM WITHIN THE JET ENGINES 4HE JET ENGINE CAUSED MODULATION IS CALLED *ET %NGINE  -ODULATION *%-  SPECTRAL MODULATION LINES 4HE HIGH 
 The coupled  signals add vectorially to produce a wave traveling toward the generator of element  00 that appears to be a reflection from the radiator of element 00. As the phases of  the neighboring elements are varied to scan the beam, the vector sum of the coupled  signals changes and causes an apparent change in the impedance of element 00. For  some scan angles, the coupled voltages tend to add in phase, causing a large reflection  and possibly the loss of the main beam. 
 The dashed lines are plotted by summing the Rayleigh  cross section or Eq. (13.17) over unit volume and substituting Eq. ( 13.21) to give  '1 =La;= 7J4rt.6 x 10 12 m2/m3  i (13.23)  where f is the radar frequency in GHz and r the rainfall rate in mm/h. 
 2.l. Reed, J.E.: The AN/FPS-85 Radar System, Proc. IEEE, vol. 
 This problem may be reduced by allowing some aperture  overlap but at the price of loss of angle sensitivity and antenna gain. Electronic Scan Phased Array Monopulse.  Tracking radars dedicated to single  target tracking can provide very high precision long range performance, such as the  AN/FPQ-614,15,16 (Figure 9.1 a) with a specified precision of 0.05 milliradian. 
 A.: The lnnuence of Atmospheric Conditions ·on Radar Performance, J. Inst. Navigation  (Lo11do11). 
 Prengaman, R. E. Thurber, and W. 
 NOISE 
 T able 1. Parameters of the system. Parameters V alue Velocity 102 m/s Frequency band 9.6 GHz Bandwidth 600 MHz PRF 312 Hz Angle range −30◦–30◦ Reference range 34 km Figure 15a,b are images of six vehicles with forward-looking and backward-looking views. 
 Civil marine radars are available at both S band  ( 10 cm wavelength) and X band (3 cm). Although both bands have distinctive advantages for  ship application. when only a single radar is employed it is usually at X band for the reasons  given above. 
 114, John  Wiley & Sons, Inc., New York, 1957.  30. Peterson, W. 
 When a linear-FM waveform is desired, the phase samples follow a quadratic pattern and can be generated by two cascaded digital integrators. The input dig- ital command to the first integrator defines this quadratic phase function. The dig- ital command to the second integrator is the output of the first integrator plus the desired carrier frequency. 
 Instead, MTI systems reject fixed clutter through a subtraction process  while retaining moving targets. 2. Transmitter intrapulse anomalies have no affect on MTI performance if they repeat  precisely pulse-to-pulse. 
 1996 ,34, 212–218. [ CrossRef ] 13. Liang, C.; Fielding, E.J. 
 Otherwise,transmission would occur during reception of the reﬂected echo of theprecedingpulse.Usingthesameantennaforbothtransmittingandreceiving,the relatively weak reﬂected echo would be blocked by the relatively strongtransmitted pulse. Sufﬁcient time must be allowed between each transmitted pulse for an echo to return from any target located within the maximum workable rangeof the system. Otherwise, the reception of the echoes from the more distanttargets would be blocked by succeeding transmitted pulses. 
 PLING  OR PERHAPS BECAUSE OF IT  THE MORE CLOSELY THE DIPOLES WERE SPACED  THE SMALLER THE IMPEDANCE VARIATION WITH SCANNING !LTHOUGH THE IMPEDANCE VARIATION DECREASED  THE ABSOLUTE IMPEDANCE OF THE DIPOLES ALSO DECREASED  MAKING THEM MORE DIFFICULT TO MATCH AT BROADSIDE )T IS EXPECTED THAT TO OBTAIN AN IMPEDANCE VARIATION SMALLER THAN THAT OF FREE SPACE SOME IMPEDANCE COMPENSATION MUST BE EMPLOYED -UTUAL #OUPLING AND 3URFACE 7AVES  4HE MUTUAL COUPLING BETWEEN TWO SMALL  ISOLATED DIPOLES  SHOULD DECREASE AS  R IN THE ( PLANE AND  R IN THE % PLANE % AND  ( PLANES ARE INTERCHANGED FOR SLOTS  #OUPLING MEASUREMENTS HAVE SHOWN THAT IN THE  ARRAY ENVIRONMENT THE RATE OF DECAY IS SLIGHTLY GREATER THAN PREDICTED ABOVE  INDICATING THAT SOME OF THE ENERGY IS DELIVERED TO OTHER ELEMENTS IN THE ARRAY AND MAY BE DIS 
 TIME RADAR $30 SYSTEMS  WERE BUILT USING DISCRETE LOGIC 4HESE SYSTEMS WERE VERY DIFFICULT TO DEVELOP AND MOD 
 Xiong, T.; Wang, S.; Hou, B.; Wang, Y.; Liu, H. A resample-based SVA algorithm for sidelobe reduction of SAR/ISAR imagery with noninteger Nyquist sampling rate. IEEE T rans. 
 WAVE PROPAGATION PRIMARILY THROUGH THE SPACE 
 Note:  Target and clutter powers are measured on a single pulse return and all target velocities  are assumed equally likely. The subclutter visibility (SCV) of a radar system is a measure of its ability to detect  moving-target signals superimposed on clutter signals. A radar with 20 dB SCV can  detect an aircraft flying over clutter whose signal return is 100 times stronger. 
 ARRAY RADAR CONSIDERED HERE IS A MULTIFUNCTIONAL ONE  IT HAS ALSO  A TRACKING MODE THAT MIGHT BE AFFECTED BY THE 2'0/ FOR THIS REASON  AN ! 
  
 CIFICALLY IN THE CONTEXT OF THE KEY PERFORMANCE LIMITERS TO AIRBORNE -4) RADAR CLUT 
 August/September 1976.  85. Johnson, C. 
 J. C. Hubbert, V. 
 The apertures would normally be tilted back from the vertical to balance the scan angles. Radiating Elements. The most commonly used radiators for phased arrays are dipoles, slots, open-ended waveguides (or small horns), and printed-circuit "patches" (originally called Callings radiator after their inventor24). 
 2.3 2.6 2.7   2.15  O  Ogive, radar cross section of 11.9  On-axis tracking 18.33  Operator and ECCM 9.21  Optimum clutter filters 15.16  Orbit selection for SBR 22.5  This page has been reformatted by Knovel to provide easier navigation. I.28  Index terms  Links   Oscillator versus amplifier 4.9  Outdoor test ranges 11.38  Ovals of Cassini 25.6  Over-the-horizon radar ( see HF OTH radar)  P  Paired echoes in pulse compression 10.27  Parabolic-cylinder antenna 6.10 6.11 6.15  Parabolic reflector antenna 6.10  Passive ECM 9.5  Passive tracking and radar 8.44  Patriot phased array radar 7.69  Pattern propagation factor 2.31 2.61  Pattern ranges 6.52  PAVE PAWS    5.3 5.4 5.7   5.25 7.75  Peak power 2.10  Pedestals in CFAs 4.13  Personnel detection with CW radar 14.39  Phamp        3.31  Phase-coded CW radar 14.29  Phase-coded waveforms 10.15  Phase-comparison monopulse 18.17  Phase detectors 3.32  Phase-discrimination CFAR 3.49  Phase noise in oscillators 15.48  Phase-sensitive detector 3.33  Phase shifters 7.63  Phase tracker 3.33  Phased array radar:  adaptive     9.14  This page has been reformatted by Knovel to provide easier navigation. I.29  Index terms  Links   Phased array radar:  (Continued)   aperture matching of 7.22  bandwidth of 7.49  bandwidth limitation in 7.3  beam-pointing accuracy of 7.43  beam steering in 7.13 7.17  circular polarization in 7.6  conformal    7.3  constrained feeds for 7.58  digital beamforming in 7.8  diode phasers for 7.63  dual-mode phasers for 7.66  element impedance in 7.27  element pattern in 7.25  element phasing in 7.21  errors in    7.38  feed networks for 7.58  ferrite phasers for 7.64  frequency scanning of 7.8  fundamental relationships in 7.2  grating lobes in 7.10 7.19  height finding with 20.11  illumination functions for 7.37  lens array 7.48  linear       7.10  low sidelobes in 7.37  monitoring of 7.4  monopulse    7.4 18.19  multifunction 7.1  mutual coupling in 7.23  optical feeds for 7.58  parallel feeds for 7.60  This page has been reformatted by Knovel to provide easier navigation. 
 Root: '4An Introduction to the Theory of Random Signals and Noise," McGraw-Hill Publishing Company, New York, 1958. 44. Zrnic, D. 
 Thedifference between theposition measured hytheopticsandthat. IRACKING RADAR 181  nlcasurcd by tlic radar is ol,tai~lcd after correctio~i is made for tl~c dini're~ice ill atmosplic~.ic  refractior~ for optical arid KF propagation. This type of dynarnic calibratiorl requires ttie radar  to f7e I;irgc CI~OLI~II to track satellilcs. 
 [ CrossRef ] 25. Romeiser, R.; Alpers, W. An improved composite surface model for the radar backscattering cross section of the ocean surface: 2. 
 PLANE IMAGERY WITH  MINIMAL DISTORTION IS NECESSARY IF COMPARISON IS TO BE MADE WITH MAPS OR WITH IMAGING TAKEN FROM OTHER SENSORS  SUCH AS OPTICAL SENSORS OR OTHER 3!2S.   39.4(%4)# !0%2452% 2!$!2   £Ç°£Î 0ULSE 2EPETITION &REQUENCY 02&  2EQUIREMENTS FOR 3!2  &OR BROADSIDE  OPERATION  THE APPARENT ANGULAR VELOCITY OF THE SCENE ROTATION IS   7 6 2    7 ITH RESPECT TO THE RADAR  THE RELATIVE VELOCITY OF POINT  ! SEE &IGURE   AT THE  FIRST NULL OF THE MAIN BEAM IS   VR6 22 $6 $! 
 If this should change byanamount ATfrom one pulse tothenext, there will beanuncanceled spike ofwidth A,. Thus weshould not allow A,/r to exceed 4percent. Variation inpulse length can also cause anindirect effect onthephase ofthecoherent oscillator when thelatter isnot intune with thei-fecho signals. 
 FIELD RANGE IS THAT  THE AMPLITUDE AND PHASE OF EACH ELEMENT CAN BE MEASURED AND A FULL HEMISPHERIC ANTENNA PATTERN CAN BE GENERATED .EAR 
 SEC. 9.25] EXAMPLES OF RADOMES 317 will determine whether theproblem isone ofstrength orstability. The stability problem isadifficult one tomeet, since noribs orother means ofreinforcement can beused forthe extensive transparent area because ofpossible distortion ofthe electrical pattern. 
 58. Caspers. J. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 12.8  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 For feeds with conducting walls, the effective H-plane width, w', is at least l/4 and  increases with depth D:  ′= + { } w w D max / , /λ λ4 2 (12.16) where max indicates taking the larger of the two values. 
 For example, in Figure 16.46 c, one could syn - thesize a 20 ° orientation angle for a linear polarization to emphasize this class or use  vertical polarization to suppress the dominant class in the image. Various authors168,169  have shown that one can synthesize an elliptical polarization that increases the target- to-clutter ratio where the target is, for example, a manmade object. Swartz et al.169  found a polarization that gave a 9.4 dB target-to-clutter ratio where the target was an  urban area and the clutter was represented by a park in the San Francisco image used  to produce Figure 16.46. 
 Willis23.1 23.1  Concept and Definitions / 23.1 23.2  Coordinate Systems / 23.3 23.3  Bistatic Radar Equation / 23.4 23.4  Applications / 23.9 23.5  Bistatic Doppler / 23.14 23.6  Target Location / 23.17 23.7  Target Cross Section / 23.19 23.8  Surface Clutter / 23.22 23.9  Unique Problems and Requirements / 23.26 Chapter 24 Electronic Counter-Countermeasures Alfonso Farina24.1 24.1  Introduction / 24.1 24.2  Terminology / 24.2 24.3  Electronic Warfare Support Measures / 24.2 24.4  Electronic Countermeasures / 24.5 24.5  Objectives and Taxonomy of ECCM Techniques / 24.8 24.6  Antenna-related ECCM / 24.10 24.7  Transmitter-related ECCM / 24.31 24.8  Receiver-related ECCM / 24.32 24.9  Signal-processing-related ECCM / 24.33 24.10  Operational-deployment Techniques / 24.36 24.11  Application of ECCM Techniques / 24.37 24.12  ECCM and ECM Efficacy / 24.54   Acronym List / 24.56   Acknowledgments / 24.58. Chapter 25 Radar Di gital Si gnal Processin g James J. Alter and Jeffrey O. 
 6. Microwave Engineers Handbook and Buyers Guide , New York: Horizon House, 1964, p. 143. 
 on Antennas and Propagation , IEE Conf. Pub. no. 
  
 If a canceler is used, filter weighting can be relaxed over that with a filter bank alone, since the canceler reduces the dynamic-range requirements into the FFT (if the main-beam clutter is the largest signal). Without a canceler, heavier weighting is needed to reduce sidelobes to a level so that the filter response to main-beam clutter is below the thermal-noise level. This weighting increases the filter noise bandwidth and hence increases the loss in signal-to-noise ratio. 
 23. Croney, J.: Improved Radar Visibility of Small Targets in Sea Clutter, The Rudio und Electrot~ic  Engineer, vol. 32, pp. 
 Althougi~ it is  ltttractivc for opcratiori ill aircraft wliere space and weight must be kept to a mininli~ltl, its  MI'I performance is limited, as is its ground-based counterpart, by the lack of spectral purity  of the clutter when used as a reference signal, and by the spatial inhomogeneity (or patchiness)  of tlie clutter.  hloving clutter and stationary radar. The discussion in this section has been concerned with  tlie operation of an MTI radar wlien the clutter doppler-frequency was not at dc but had some  - lirlitc vnluc hccausc of tlre n~otioti of the vehicle carrying tlie radar. 
 However, one cannot ignore the RF portion of the receiver merely by making it have wide bandwidth. Section 3.2 discussed . TABLE 3.1 Noise and Dynamic-Range Characteristics * CW output-CW input on the center frequency, not coded pulse. 
 210 INTRODUCTION TO RADAR SYSTEMS  amplification, the phase velocity must be near the velocity of the electron stream.) A htrckward-  wave interaction takes place when the phase velocity is in the direction opposite that of the  group velocity. The forward-wave CFA can operate over a broad range of frequency with a  constant anode voltage, with only a small variation in the output power. On the other hand,  the power output of a backward-wave CFA, with a constant anode voltage, varies with  frequency. 
  %ACH -273  DWELL IS MADE UP OF . LOOKS EACH WITH A  DIFFERENT 02&  $ETECTION IS REQUIRED ON AT LEAST  - LOOKS TO RESOLVE TARGET  RANGE AND RANGE RATE UNAM 
 This is applicable only when the first blind speed is high (a low radar  frequency and/or high prf) and when the platform speed is low, as it would be with a ship­ mounted radar.  Generally, most clutter-lock MTI techniques· do not adequately eliminate both stationary  and moving clutter when they appear simultaneously within the same range resolution cell. A  TACCAR, for example, might be designed to reject ground clutter close in, and weather or  chaff at a different doppler at ranges beyond the ground clutter; but not to cancel two different  clutter doppler frequencies simultaneously.8 An exception is the adaptive MTI62•65 which can  adapt to any type of clutter. 
 # GENERALLY REFER TO ANALOG AMPLIFIERS WHEREAS #LASS 
 ( a) The result of sorting the RCS amplitudes into descending order and calculation of the energy concentration. ( b) The result of mean value calculation for the noise. ( c) The result of threshold value calculation. 
 Decreasing  sidelobes are not undesired in radar application. If the radar designer has a choice, it is  preferred that the high sidelobes be near the main beam, where they are easier to recognize,  rather than to have isolated high sidelobes elsewhere. This is one time nature is cooperative  since it is natural for the sidelobes to be large in the vicinity of the main beam. 
 Occasionally, a  second order intercept point specification is also required for very wide bandwidth sig - nals. It should be noted that for amplifiers, compression point and third order intercept  are usually specified at their output whereas for mixers these parameters are usually  specified at their input. Additional specifications for mixers include LO drive power, port-to-port isolation,  and single tone intermodulation levels. 
 Time sidelobe levels of –35 dB  have been achieved for TB between 5 and 15. TB products of up to 2000 have been  achieved12 with time sidelobes better than –40 dB.13 Dynamic range is limited by non - linearities in the crystal material, but dynamic ranges over 90 dB have been achieved.  The most common SAW materials are quartz, lithium niobate, and lithium tantalite . 
 $ IS THE .EXRAD DOPPLER RADAR THAT FIRST ENTERED SERVICE IN  4HE LETTER $ INDICATES IT IS A DOPPLER WEATHER RADAR.   !. ).42/$5#4)/. !.$ /6%26)%7 /& 2!$!2   £°£ £°nÊ -" 
 RADIATION MISSILE !2-   HAVING  THE OBJECTIVE OF HOMING ON AND DESTROYING THE VICTIM RADAR 4HE SORTING AND ACQUISITION OF RADAR SIGNALS IS PRELIMINARILY MADE BY AN %3- SYSTEM AFTERWARD IT CUES THE !2-  WHICH CONTINUES HOMING ON THE VICTIM RADAR BY MEANS OF ITS OWN ANTENNA  RECEIVER  AND SIGNAL PROCESSOR !CQUISITION DEPENDS ON THE DIRECTION OF ARRIVAL $O!   OPERATING BAND  CARRIER FREQUENCY  PULSE WIDTH  02)  SCAN RATE  AND OTHER PARAMETERS OF THE VICTIM RADAR !N !2- HOMES ON THE CONTINUOUS RADIATION FROM THE RADAR SIDELOBES OR ON THE FLASH OF ENERGY FROM THE MAIN BEAM !2- BENEFITS FROM THE ONE 
 Seaborne radar may have to be several  hundred feet away from its aerials, and the pulse system  and high frequencies used are such that a single linking-  wire, such as the ‘lead-in’ of a broadcast receiver from  its aerial, is quite impracticable. To carry the radio-  frequency energy from the radar transmitter to the  aerial, and the echo back from the aerial to the receiver,  we must have feeders, or transmission lines, as they are  sometimes called, carefully balanced to the circuits they  link. This system of feeders is similar in theory to the  transmission-line theory used for commercial and broad-  cast transmitters. 
 10”3a), each ofwhose cavities may bethought ofasaquarter-wave line (see also Fig. 10.22). Itisalow-impedance oscillator having alarge Cand small L.The vane type (Fig. 
 IRE, vol. 46, p. 2a, May, 1958. 
 Geosci. Remote Sens. 2014 ,52, 640–650. 
 28. Ruze, J.: Lateral Feed Displacement in a Paraboloid, IEEE Trans., vol. AP-13. 
 Microwat•e J .. vol. 16, pp. 
 LOOKING ANGLE MEASUREMENT SYSTEMA DIFFERENCE THAT THE INTERPRETER MUST UNDERSTAND !T LOW GRAZING ANGLES  THE DISTORTIONS ARE SMALL FOR RADAR  BUT AT LOW INCIDENCE ANGLES  THEY ARE LARGE -OREOVER  THE SPECKLE IN RADAR IMAGES IS NOT PRESENT IN PHOTOGRAPHS -ODERN IMAGING RADARS USE DIGITAL RECORDING AND PROCESSING  AND THE IMAGES ARE  PRODUCED ON FILM OR MANIPULATED DIGITALLY "ECAUSE THE SIDE 
 WELL DERRICKS  PER UNIT AREA  IS NOT IMPORTANT  BECAUSE THE -4) RADAR DESIGNER MUST CREATE A ROBUST SYSTEM THAT WILL FUNCTION WELL NO MATTER THE ACTUAL DEVIATION FROM THE CLUTTER MODELS OF REAL CLUTTER ENCOUNTERED -4) RADARS MAY USE ROTATING ANTENNAS OR FIXED APERTURES WITH ELECTRONIC BEAM SCAN 
 a"    AND  ( J" J"    \\  \ \V 'VV V VV  y 
 TERING FROM SOIL INCLUDES TWO 
 revised and polished the paper. Funding: This work is supported by the National Natural Science Foundation of China, grant numbers 61372163, 61331015 and 61601035. Acknowledgments: The authors would like to thank the anonymous reviewers for their competent comments and helpful suggestions.Conﬂicts of Interest: The authors declare no conﬂict of interest. 
 MENTS OF THE %5 4HE %UROPEAN 4ELECOMMUNICATIONS 3TANDARDS )NSTITUTE %43)  REGULATORY BODY IS IN THE PROCESS OF DRAFTING SPECIFICATIONS AND INFORMATION CAN BE FOUND AT HTTPWWWETSIORG THAT WILL COVER THE USE OF SUCH EQUIPMENT AS A DELIBER 
                                     
 IEEE, vol. 56.  pp. 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars.  SPACE-BASED REMOTE SENSING RADARS  18.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 Seasat . The generally acknowledged space-based synthetic aperture radar pio - neer was the 1978 Seasat SAR (Figure 18-1). 
 TRATES THE TRACKING OF A SINGLE TARGET USING MULTIPLE HYPOTHESIS TECHNIQUES )N THIS EXAMPLE  MANY HYPOTHESES ARE FORMED AND  OVER SUCCESSIVE MEASUREMENT INTERVALS  SUCCESSFULLY PRUNED AWAY LEAVING ONLY ONE CORRECT TRACK 4HE REGION OF APPLICABILITY FOR THE MORE SOPHISTICATED ALGORITHMS IS DETERMINED BY TWO  PARAMETERS THE DENSITY OF EXTRANEOUS DETECTIONS  K DETECTIONS PER UNIT AREA OR VOLUME    &)'52%  ! COMPARISON OF THE EXECUTION TIME FOR  THE -UNKRES OPTIMUM   *6# OPTIMUM   AND !UCTION  SUBOPTIMUM  ALGORITHMS SHOWS THE RAPID INCREASE IN COMPUTATION REQUIRED FOR -UNKRES AS THE NUMBER OF ROWS IN THE ASSIGNMENT MATRIX INCREASES 4HE *6# AND AUCTION ALGORITHMS SHOW MUCH MORE GRADUAL GROWTH AFTER ) +ADAR ET AL  Ú 30)%  &)'52%   %XAMPLE OF THE USE OF MULTIPLE HYPOTHESIS TRACKING ON  SCANS OF SIMULATED RADAR DATA  CONTAINING A SINGLE TARGET AND MANY FALSE ALARMS  A  SHOWS ALL HYPOTHESES FORMS AND  B  SHOWS THE SINGLE  HYPOTHESIS SELECTED 0RUNED HYPOTHESES ARE GRAYED OUT  AFTER 7 +OCH Ú )%%%  . 
 ART DEINTERLEAVING SIGNAL PRO 
 12.5 makes the values from O to 5° low. Effects of Roughness, Moisture Content, and Vegetation Cover. Scattering falls off more rapidly with angle for smooth surfaces than for rough surfaces. 
 The characteristic feature of a fog is the reduction in visibility. Visibility is defined as the greatest distance in a given direction at which it is just possible to see and identify with the unaided eye (1) in the daytime a prominent dark object against the sky at the horizon and (2) at night a known, preferably unfocused, moderately intense light source.32 Although the visibility depends upon both drop size and number of drops and not entirely upon the liquid-water content, in practice the visibility is an approx- imation of the liquid-water content and therefore may be used to estimate radio- wave attenuation.33 On the basis of Ryde's work, Saxton and Hopkins34 give the figures in Table 23.5 for the attenuation in a fog or clouds at O0C temperature. The attenuation varies with the temperature because the dielectric constant of water varies with temperature; therefore, at 15 and 250C the figures in Table 23.5 should be multiplied by 0.6 and 0.4, respectively. 
 49. Di Nardo, U.: Adaptivity Criteria of a Modern Air Traffic Control Radar, RiPista Ternirn Sele11ia  (Rome), vol. 2, no. 
 6.40  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 A/D Converter Sample Clock Stability.  The stability of the sample clock is  critical to achieving the full capability of an A/D converter. Sample-to-sample varia - tion in the sampling interval, called aperture uncertainty  or aperture jitter , produces  a sampling error, proportional to the rate of change of input voltage. 
 STATE TRANSMITTERS EFFECTIVELY )T ALSO TOOK IMPORTANT ADVANTAGE OF ADVANCES IN DIGITAL RECEIVERS AND DIGITAL PROCESSING THAT OCCURRED SINCE THE DEVELOPMENT OF THE !32 
 In the case of two beams, the aperture phase slope has the average inclination and varies periodically from O to TT. It should be noted that when a multilobed radiation pattern is received or transmitted in one channel, the gain is shared between the lobes. When the beams are contained in separate (beamforming) channels, however, each channel has the full gain of the aperture. 
 A feasible technique for separating the received signal from the transmitted signal  when there is relative motion between radar and target is based on recognizing the change in  the echo-signal frequency caused by the doppler effect.  It is well known in the fields of optics and acoustics that if either the source of oscillation  or the observer of the oscillation is in motion, an apparent shift in frequency will result. This is  the dopplrr eJfect and is the basis of CW radar. 
 DIMENSIONAL AIR MOTION . £°Î{  2!$!2 (!.$"//+  FIELDS IN PRECIPITATION 4HIS PIONEERING WORK LED THE WAY TOWARD THE USE OF NETWORKS  OF DOPPLER RADARS FOR STUDIES OF INDIVIDUAL CLOUDS TO EXAMINE THE THREE 
 The synchronism between  the electromagnetic wave propagating along the stow-wave structure and the d-c electron  beam results in a cumulative interaction w~ich transfers energy from the d-c electron beam to  the RF wave, causing the RF wave to be amplified.  The simple helix was used as the slow-wave structure in the early TWTs and is still  preferred in traveling-wave tubes at power levels up to a few kilowatts. It is capable or wider  bandwidth than other slow-wave structures, but its power limitations do not make it suitable  for most high-power radar applications. 
 EDGE RIDGE  CHARACTERISTIC ASSOCIATED WITH ,&- WAVEFORMS  AS CONTRASTED WITH THE THUMBTACK CHARACTERISTIC OF PSEUDORANDOM SEQUENCES &IGURE   (OWEVER  FOR SMALL RATIOS OF DOPPLER SHIFT TO WAVEFORM BANDWIDTH  A GOOD DOPPLER RESPONSE CAN BE OBTAINED FOR REASONABLE TARGET VELOCITIES ,EWIS AND +RETSCHMER #ODES 0  0  0  0   ,EWIS AND +RETSCHMER HAVE STUD 
 Someformofadaptation tomaneuvers isrequired.76TheKalman filterissophisticated and accurate, butismorecostlytoimplement thantheseveralothermethods commonly usedfor thesmoothing andprediction oftracking data.77Itschiefadvantage overtheclassical ex-fi trackerisitsinherent abilitytotakeaccountofmaneuver statistics. If,however, theKalman",filterwererestrictedtomodeling thetargettrajectory asastraightlineandifthemeasurement noiseandthetrajectory disturbance noiseweremodeled aswhite,gaussian noisewithzero mean,theKalman filterequations reducetotheex-pfilterequations withtheparameters exand {1computed sequentially bytheKalman filterprocedure. Theclassical ex-f3tracking filterisrelatively easytoimplement. 
 Thecurvelabeled ..Rayleigh lineardetector" applies totheconventional receiver with Rayleigh clutterornoise.Thecurve labeled..Chernoff bound"provides anupperboundtotheoptimum detector fortheparticular clutter modelindicated. (After Scltlelter.14•Z8collrteS)' IfEE.)995 99- 98-Chernoff bound'-----' 95·- 90.c 9Rayleighu Linearv80- linearenvelope/envelope 4i l:J70deteclor 'detectora"~. >-60 nSU0na40-'-Q 30-Binary 20inlegrolor , m=7 '-- 10· 5024 18 999 998 Rayleigh Chernoff 995. 
 TRIP RANGE AT TWO DIFFERENT FREQUENCIES 4HE DELAYS IMPOSED BY THE ATMOSPHERE ARE COMPRISED OF TWO COMPONENTS THE DRY ATMOSPHERE AND WATER 
 23.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 Bistatic Radar Nicholas J. Willis Technology Service Corporation (retired) 23.1 CONCEPT AND DEFINITIONS A bistatic radar uses antennas at separate sites for transmission and reception. 
 92–93, April 1980.  7. A. 
 5.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 looks in each beam create as many as 64 independent looks. The shortest range at the  bottom of the elevation scan uses a short pulse with no pulse compression and a much  higher PRF, but the same number of looks. The pulses in a TOT are all the pulses that  illuminate a single spot from the overlapping beams. 
 ALARM CONTROL IN RECEIVERS WITHOUT DOPPLER FILTERS IS SOMETIMES DEGRADED BY  ERRORS OF A SMALL FRACTION OF THE LEAST SIGNIFICANT BIT ,3"   SO CORRECTION IS PREFERABLY APPLIED AT THE ANALOG INPUT TO THE !$ $# OFFSETS CAN BE MEASURED USING DIGITAL PRO 
 BASED SOUNDERS  TOTAL ELECTRON CONTENT 4%#  DERIVED FROM '03  56 AIRGLOW DATA  AND IN SITU MEASUREMENTS OF ELECTRON DENSITY FROM SATELLITES AND OTHER SOURCES /FTEN THE ASSIMILATION IS  PERFORMED WITHIN AN EXTENDED  +ALMAN FILTER FRAME 
 This circuit then commands the PRF to change value in an attempt to bring the target out of eclipse. The problems with this approach are that target scintillation can cause PRF cycling and that there is no accurate way to predict which PRF will prevent eclipse. The latter problem can be reduced, if crude FM range data is available, by selecting the PRF from groups of PRFs, each group having values appropriate for a particular region of ranges. 
 J. Bennett, W. L. 
 Decrease of total power gain: Uniform current distribution among gate fingers becomes increasingly difficult to manage as the number of paralleled gates increases. Combining inefficiencies result, and the overall device gain decreases. 4. 
 The center of the feed is placed at the focus of  the parabola, but t11c Iior~t is tipped wit11 respect to tlie parabola's axis. The major portioti of  the lower half of the parabola is removed, leaving that portion shown by the solid curve it1  Fig. 7.10. 
 K.: A Digital Mean-Clutter-Doppler Compensation System, NRL Mmioratidrtnl Reporl  2772, Naval Research Laboratory, Washington, D.C., April. 1974.  73. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers.  RADAR RECEIVERS  6.36x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 The block diagram shown in Figure 6.1 includes sensitivity time control (STC)  attenuation at the RF input. 
 Likewise, the  probability-density function for the envelope of 11 signal-plus-noise pulses is  " P.,(11, v;) = n Ps(v;) (10.34)  i= I  The probability-density function for signal-plus-noise, Ps(v;), 1s the Rice distribution of  Eq. (2.27)  (2.27)  where a = ratio of signal (sine-wave) amplitude to rms noise voltage and I 0(x) = modified  Bessel function of zero order. The detection process is equivalent tt, determining which of the  two density functions [Eq. 
 A large  measure of gratitude must be expressed to those radar engineers who have taken the time and  energy to ensure that the results ,of their work were made available hy publication in  recognizecj journals.  On a more personal note, neither edition of this book could have been written without the  complete support and patience of my wife Judith and my entire family who allowed me the  time necessary to undertake this work.  Merrill I. 
  D"   
 LAR ABSORBERS )NTENDED PRIMARILY FOR SUPPRESSION OF SURFACE TRAVELING 
 Spotlight SAR data processing using the frequency scaling algorithm. IEEE T rans. Geosci. 
 Ill.129 equipment instahilities. 130-131 limiting, lJ6-138 quantization. 120 interclutter visibility, 130.494-495 limiting in,136-138 Moving TargetDetector, 127-129 multiple prf's,114-117 noncoherent, 138-139 nonrecursive filter.110 phasedetector, 105 quadrature channel, 119 quantization, 120 recursive filter,113 reference gain,III second-time-around echoes,117 staggered pr~114-117 stalo,105 storagetube,126 suhclutter visibility, 129-130 TACCAR,142 three-pulse canceler, 109--110 transient response, 113 114 transversal filter,110-114 two-frequency, 147-148 visibility factor,130 Mubisantenna, 316 Multifunction array,323 Multifunction radar,337 Multimode feeds,inmonopulse, 164 Multipactor duplexer, 365INDEX577 Multipath: andantenna lobing,442-447 intracking radar,172 Multiple beams,inarrays,310-318 Multiple-frequency CWradar,95-98 Multiple prf,inMTI,114-117 Mutualcoupling, 306 n-barscan,178 Nearfield,antenna,228 Neyman-Pearson observer, 376 Nodding-beam heightfinder,541-542 Nodding scan,178 Noise: inangletracking, 167-170 atmospheric, 461-463 environmental, 461-465 inrangetracking, 177 Noisebandwidth, 18 Noisefactor,344 Noisefigure,344-347, 350-351 Noisejamming, 548-551 Noisetemperature, 345-346 Noise-temperature ratio,347 Nomenclature, letterband,8 Noncoherent AMTJ,J47 Noncoherent integration, 29-32 Noncoherent MTI,138-139 Nonlinear-contact scattering effects,437 Nonlinear FMpulsecompression, 431 Nonmatched filter,374-375 Nonparametric detector, 393 Nonrecursive filter,110 Nonwhite noisematched filter,375 O-typetube,200 Off-axis tracking, 174 Offsetfeed,239 Oilslicks,482 On-axis tracking, 180-181 Operator loss,60-61 Operator, radar,386-387 Optical processing, 523-526 Optimum detector law,382-384 Organ-pipe scanner, 247-248 Over-the-horizon (OTH)radar,529-536 Overall noisefigure,345 Palmerscan,177 Parabolic cylinder, 235-236 Parabolic reflector antennas, 235-243 Parabolic torus,236,246-247 Paraboloid, 235 Parallel-fed array,283,285. 
 Iftherate ofrotation were much faster than 1/0.72 secor1.4rps, aretentive screen could beused toaccumulate information over several revolutions until allgaps were filled. butthetime forcollecting acomplete picture would again be0.72 secorlonger. Asamatter offact, rotation atarate higher than 1.4rpsisruled out byquite another consideration. 
 SIDELOBE ANTENNAS 4HESE COM 
 The protection of Quartu Sant’Elena and its territory Andrea Pirinu, Raffaele Argiolas and Nicola Paba Drop weight impact measurements of HE sensitivity: modified detection methods D N Preston, G W Brown, B C Tappan et al.. Airborne Maritime Surveillance Radar, Volume 1 British ASV radars in WWII 1939–1945. Airborne Maritime Surveillance Radar, Volume 1 British ASV radars in WWII 1939–1945 Simon Watts Morgan & Claypool Publishers. 
 A "typical" earth radius for refractive effects is  four-thirds the actual radius. At times, atmospheric conditions might cause more than usual  bending of the radar rays, with the result that the radar range will be considerably increased.  This condition is called superrefraction, or ducting, and is a form of anomalous propagation. 
 GRASS PRAIRIE v  2EMOTE 3ENSING %NVIRON   VOL     PP n    2 :OUGHI  , + 7U  AND 2 + -OORE  h)DENTIFICATION OF MAJOR BACKSCATTERING SOURCES IN TREES  AND SHRUBS AT  '(Z v 2EMOTE 3ENSING %NVIRON  VOL   PP n    * & 0ARIS  h0ROBING THICK VEGETATION CANOPIES WITH A FIELD MICROWAVE SPECTROMETER v  )%%% 4RANS   VOL '% 
 The cell area is a minimum at (3 = 90°. FIG. 25.4 Geometry for clutter cell areas. 
 The maximum PRF and, consequently, maximum scan rate are limited by the maximum range of targets to be tracked by the radar. At a PRF of 1000 Hz the unambiguous range extends to about 80 nmi (at this range the echo is returning at the time when the radar is ready for its next transmission). The radar can track beyond this range by using Aith-time-around tracking as described in Sec. 
 ING RATE RADAR  THE UNAMBIGUOUS DOPPLER FREQUENCY .YQUIST FREQUENCY  FOR A FIXED PULSE 
 XIII Developed from ASV Mk. XI; Mk XIIIA was used by the FAA and in Mosquito aircraft of Coastal Command; Mk. XIIIB was used inBeaufighter and Brigand aircraft of Coastal Command. 
  57" 3!2v  0ROCEEDINGS 30)%  VOL   P n    , - ( 5LANDER AND 0 / &ROLIND  h0RECISION PROCESSING OF #!2!"!3 (&6(& 
 DICTS WHERE IT SHOULD BE THE NEXT TIME THE BEAM LOOKS AT THE TARGET 4HE LAG ERROR  IN THIS CASE  IS DEPENDENT ON MANY FACTORS  INCLUDING THE ACCURACY OF THE VALUE OF ANGLE SENSITIVITY USED TO CONVERT ERROR VOLTAGES TO ANGULAR ERROR  THE SIZE OF THE PREVIOUS TRACKING ERROR  AND THE TIME INTERVAL BETWEEN LOOKS &)'52%    A  #LOSED 
 J.: The Systematic Design of the Butler Matrix. lEEE TIIJIIS.. vol. 
 SIGNAL RATIO INCREASES WITH RANGE AND IS  D" AT  NMI ,ARGE CLUTTER 
 10 dB over the range 0.4 to 0.2 nmi at 1000 ft (or between 1 and 0.8 nmi at 3000 ft), compared with the modi ﬁed ASV Mk. VI pattern. A good approach to designing the elevation pattern is to use a cosec2shape, starting from about the −3 dB gain point in the downward direction (positiv e depression). 
 The original fa)se-alarm time of Marcum 10 is different from that used in this text. He  defined it as the time in which the probability is l/2 that a false alarm will not occur. A  comparison of the two definitions is given by Hollis.12 Marcum's definition of false-alarm time  is seldom used, although his definition of false-alarm number is often found. 
 Kelleher, K. S., and H. H. 
 6 COS P  &IGURE  B  )N $ SPACE  SURFACES OF CONSTANT  6,/3 ARE CIRCULAR CONES WITH  AXIS 6 AND GENERATING ANGLE  P  WITH THE RADAR AT THE VERTEX 4HE NEGATIVE SIGN OCCURS  &)'52%   2ANGE AND VELOCITY CONTOURS IN $ SPACE  A  #ONSTANT 
 M RESOLUTION IN 3!2 MAPPING MODE   
 Electron. 2017 ,28, 199–211. [ CrossRef ] 9. 
 A standard additive coherent summation (overlaying) of consecutive complex images is applied to reduce the level of the additive white Gaussian noise. The process of the noise depression and image quality improving by additive coherent summations of 3, 8, and 10 complex images is illustrated in Figures 9–11, respectively. 113. 
 Other subjects that are new or which have seen significant  cliaiiges in the current edition include low-angle tracking, " on-axis" tracking, solid-state RF  ources, the mirror-scan antet~na, antenna stabilization, computer control of phased arrays,  olid-state duplexers, CFAR, pulse compression, target classification, synthetic-aperture radar,  ver-the-horizon radar, air-surveillance radar, height-finder and 3D radar, and ECCM. The  bistatic radar and millimeter-wave radar are also included even though their applications have  PREFACE Although thefundamentals ofradarhavechanged littlesincethepublication ofthefirst edition. therehasbeencontinual development ofnewradarcapabilities andcontinual im­ provements tothetechnology andpracticeofradar.Thisgrowthhasnecessitated extensive revisions andtheintroduction oftopicsnotfoundintheoriginal. 
 TO 
 ! SATELLITE SCAT 
 # BIASED "*4 AMPLIFIER WILL TYPICALLY EXHIBIT A VERY NARROW hLINEARv TRANSFER CHARACTERISTIC THE LINEAR REGION MAY  EXIST OVER ONLY A NARROW   
 RESOLUTION CENTRAL SPIKE AREA AS WELL AS THE GROSS STRUCTURE OF THE  AMBIGUITY SURFACE CAN BE ACCOMPLISHED BY VARIATIONS OF THE BASIC WAVEFORM PARAM 
 0LUS 
 V . Twersky, “On the scattering and reflection of electromagnetic waves by rough surfaces,”  Trans. IRE , vol. 
 Several nonarray techniques using reflectors or lenses have  been considered for the generation of multiple beams. The Luneburg lens and the torus  reflector with multiple feeds as described in Chap. 7 are examples. 
 IEEE Std 52 1 - 1976. Nov. 30. 
 The multiple PRFs move the relative  location of the clear regions so that all-aspect target coverage is achieved. Since the  sidelobe clutter generally covers the doppler region of interest, the ratio of the region  with sidelobe clutter below noise relative to the total range-doppler space is a function  of the radar altitude, speed, and antenna sidelobe level. If a high-PRF waveform is used, the clear-range region disappears because the  sidelobe clutter folds in range into the unambiguous range interval (assuming the tar - get doppler is such that it still competes with the sidelobe clutter). 
 Aisthemaximum signaiamplitud~, and “Tisthetime interval over which theclamp istobeopened. IfE,isnot ground potential, the voltage t+ (a)iR, Ex2EO +-..!.. (b)(c) FIG. 
 Δθis the 3 dB width of the radar beam. The Doppler bandwidth of the scatterer can be derived as: Δfd=⎭vextendsingle⎭vextendsingle⎭vextendsinglefdh−fdl⎭vextendsingle⎭vextendsingle⎭vextendsingle=⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsinglef d⎭parenleftbigg θ0−Δθ 2⎭parenrightbigg −fd⎭parenleftbigg θ0+Δθ 2⎭parenrightbigg⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle=2vcosθ0cosϕ λΔθ (7) The Doppler bandwidth illustrated in Equation (7) is the frequency excursion experienced by the scatterer during the dwell time in which the scatter is illuminated by the 3 dB width of the antenna. Assuming that pulse compression and range migration correction [ 23] are performed, then the echoed signal can be written as: s(τ,t)=σ·rect⎭parenleftbiggt Ta⎭parenrightbigg sin c⎭bracketleftbigg B⎭parenleftbigg τ−2R0 c⎭parenrightbigg⎭bracketrightbigg exp⎭parenleftBigg −j4πR(t) λ⎭parenrightBigg (8) 71. 
 Radar reflector antennas can be classified in  various ways. One useful classification criteria is electrical design, i.e., the reflector optics  configuration. Table 12.1 provides a summary level comparison of some common radar   Single Reflector  ParabolicCylindrical  Reflector Dual Reflector  (Cassegrain or  Gregorian)Confocal  ParaboloidsSpherical and  Torus Electronic  Scanning (Escan)•  Limited in both  Azimuth and  Elevation •  Achieved via  Feed switching•  Wide 1D  scanning •  Uses ESA  line source  for wide 1D  scanning•  Limited in both  Azimuth and  Elevation •  Achieved via  feed switching•  Uses planar  ESA source •  Typically  limited, but  tradable  by varying  magnification•  Potential for  very wide 1D  scanning (torus)  or 2D Scanning  (spherical) •  Achieved via  feed switching  Aperture  Efficiency Feed  Type(s)•  Medium to high •  No escan : Single  horn •  Escan : Array  (switched feeds)•  Medium to  high •  1D ESA line   source• High •  No escan :   Single horn •  Escan : Array  (switched feeds)• High •  2D ESA  planar source•  Modest to low •  Switched  beam array on  circular arc  (torus reflector)  or spherical  arc (spherical  reflector) Blockage  Concerns•  Mitigate feed  blockage via  offset geometry•  Mitigate feed   blockage  via offset  geometry•  Mitigate feed  blockage via   offset geometry •  Can move feed  behind reflector•   Mitigate feed  blockage  via offset  geometry•  Serious  concern for  very wide scan  configurationsTABLE 12.1  Comparison of Key Features of Reflector Architectures ch12.indd   2 12/17/07   2:30:49 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 SLB performance can be expressed in terms of the following probabilities: (i) The  probability PB of blanking a jammer in the radar sidelobes, which is the probability of  associating the received signals ( u, v) with H2 when the same hypothesis is true; PB  is a function of the jammer-to-noise ratio (JNR) value, the blanking threshold F, and  the gain margin b = GA/Gsl of the auxiliary antenna with respect to the radar antenna  sidelobes. (ii) The probability PFA of false alarm, which is the probability of associat - ing the received signals ( u, v) with the hypothesis H1 when the true hypothesis is H0;  PFA is a function of the detection threshold a normalized to the noise power level and  of the blanking threshold F. (iii) The probability PD of detecting a target in the main  beam, which is the probability of associating the received signal ( u, v) with H1 when  the same hypothesis is true; PD depends, among other things, on the signal-to-noise  power ratio SNR, PFA, and the blanking threshold F. 
 ROW 
 Tlie frequeticy of a cotiventiorial magnetron can be changed by mechanically inserting  a ti~tiitlg C~CIIIC~~~. S~ICII as a roc!, into the iloles of the hole-and-slot resonators to change the  iridirctance of tlic resonant circuit. A titrier that consists of a series of rods inserted into each  cavity resoriator so as to alter the inductance is called a crown-of-thorns tuner, or a sprocket  trrlltlr.. 
 FIELD AMPLITUDE AND PHASE ARE CALCULATED AT A GIVEN DISTANCE FROM THE ORIGIN )F THIS FIELD IS USED AS THE ACTUAL ILLUMINATION FUNCTION  A VIRTUAL APERTURE IS CREATED WITH THE DESIRED DISTRIBUTION FUNCTION AT THE SAME DISTANCE BEHIND THE PHYSICAL  ANTENNA &IGURE A  SHOWS THE PHASE AND AMPLITUDE DISTRIBUTION REQUIRED TO FORM  A UNIFORM VIRTUAL DISTRIBUTION DISPLACED BEHIND THE PHYSICAL APERTURE )T CAN BE SHOWN  THAT IF THE PHASE OF THE ILLUMINATION FUNCTION IS REVERSED  E`    
 Hall and W. W. Shrader32 © IEEE 2007 )30 20 10 0 40 5 0 6 0012345Amplitude (Volts) (a) 10 0 20 3 0 4 0 5 0 6 0–100–50050100150200Phase (Degrees) Pulse Nu mber (b) FIGURE  2.69 (a) Three-pulse canceler residue and ( b) improvement factor for hard-   limited clutter sequence for N = 20 hits per beamwidth ( after T. 
 VERTER SAMPLING PROCESS  PRODUCING AN  UNWANTED DEGRADATION OF RECEIVER NOISE FIGURE  6IDEO AMPLIFICATION IS OFTEN REQUIRED TO INCREASE THE SIGNAL LEVEL TO THE FULL 
 (7.27) and  tcprcscrits ;I liric;~r pliasc cii;~rigc of rrn radialis across the aperture. Tlle number of sarnldes  required to approxinlatc tlie radiation pattern from a finite aperture of width d is 2dlA.  Tlic esseritial cliffererice hetween Fourier-integral synthesis and the Woodward-Levinsc-V;I  tllcthotl is tlint tlic forriicr gives a radiation pattcrn whose mcari-square deviation from 111,  desired pattern is a niiriitiiurn. 
 TheTR tube, as shown in ﬁgure 1.14 blocks the transmitter pulses from thereceiver. During the relatively long periods when the transmitter is inactive,the TR tube permits the returning echoes to pass to the receiver. To preventanyoftheveryweakechoesfrombeingabsorbedbythetransmitter,anotherdevice known as an ANTI-TR (A-TR) TUBE is used to block the passage ofthese echoes to the transmitter.. 
 9, 5  10 1023 60 10, 7  11 2047 176 II, 9 J  For large 2" -1 = N, the peak sidelobe is approximately 1/ N that of the maximum  response, measured in power. The actual values vary with the particular sequence. For exam­ ple, with N = 127, the peak sidelobe is between -18 and -19.8 dB, instead of the -21 dB  predicted on the basis of the code length. 
 IL and D. D. Howard: Precision Tracking with Monopulse Radar, Electrordcs, vol. 
 A.: Airborne Radar Motion Compensation Techniques, Evaluation of DPCA. NRL  Report 7426, Naval Research Laboratory, Washington, D.C., July 20, 1972.  64. 
 112. Tatarski, V. I.: The Effects of the Turbulent Atmosphere on Wave Propagation, TT68-50464, Na-  tional Technical Information Service, Springfield, VA, 1971. 
 The Design ofA-scopes.—This section will describe two methods for synthesizing type Adisplays, one ofextreme simplicity intended only fortest and monitoring purposes, and theother ofamore elegant form. ASimple A-scope.—In Fig. 13.41 simplicity ofdesign hasbeen carried tothe extreme inproducing anindicator intended only fortesting or monitoring applications inwhich brightness and sweep linearity arenot ofgreat importance. 
 With suitable inter-  national agreement both systems could be used with  advantage, but, of course, in civil aviation we have no  need to rely on the Gee or Loran lattices if the ground  below can be adequately covered with radar or other  beacons. The need for the lattice system is greater in  war, except over large tracts of ocean where beacons  cannot be installed except on bouys. It is too early yet  in the history of radar development to tell if a sufficient  number of radar beacons can be placed over the earth’s  surface to make other long-range navigational systems  obsolescent under civilian conditions of air travel. 
 VERTICAL AND MIDRANGE REGIONS  &IGURE  SHOWS AN EXAMPLE OF THIS VARIATION .O THEORY GIVES EXACTLY THIS RESULT  . 
 499-505, May, 1971. (Also available in ref. 1.)  9. 
 Consider a rather simplified model of a complex radar target consisting of two indepen-  dent isotropic scatterers separated by an angular distance O,>, as measureti from the ratiar.  Although such a target may be fictitious and used for reasons of mathematical simplicity, it  might approximate a target such as a small fighter aircraft with wing-tip tanks or two aircraft  targets flying in formation and located within the same radar resolution cell. It is also a close  approximation to the low-angle tracking problem in which the radar sees the target pltis its  image reflected from the surface. 
 X fr (CENTIMETERS PER SECOND) FIG. 15.17 Approximate MTI improvement factor limitation due to pulse-to-pulse stag- gering and internal-clutter motion (all canceler configurations). 7(dB) = 20 log [0.33/ (-/ - l)(X/yo-v)]; -Y = maximum period/minimum period. 
 EXCITER REQUIREMENTS 0HASE LOCKED  LOOPS ARE MORE LIKELY  USED TO LOCK FIXED HIGH 
 J. G. Fleischman, S. 
 R. Ward: Detection Performance of the Cell Averaging LOG/e'F AR Receiver,  IEEE Trans., vol. AES-8, pp. 
 If the range  variation were 10 to 1, the contribution to the dynamic range would be 40 dB. The target  cross section might also contribute another 40dB variation. Another 10 dB ought to be  allowed to account for variations in the other parameters of the radar equation. 
 A. Eshleman, and J. M. 
 133) either toproduce entirely indepcndrnt dcfkctions (winzt~qm Bdispl:~}-’). ortopro~-idc a single radial ckflcction (such asarange m~-eep~ LJ-addin~ itstwo rectangu- larcomponents ~-ectoriall~-. The latter tt,chniquc isl~sed intheRH1, the fixed-coil PPI, and inother applications. 
 WAVE 3!7  DEVICES !NALOG PULSE COMPRES 
 Inc.) . 458 INTRODUCTION TO RADAR SYSTEMS  wavelengths, the geometrical horizon represents the approximate boundary between the re­ gions of propagation and no propagation. As the frequency decreases (increasing wavelength),  Fig. 
 Itenters therange equation through itseffect onthe value ofS~~; this quantity normally varies inversely with pulse length since the receiver bandwidth, ifchosen foroptimum performance, isan inverse function ofpulse length. Before proceeding further with the analysis, adiscussion ofother quantities ~hat influ~nce the value of approximation forthe problem under varies inversely with thesquare root of thetarget.Stim will beuseful. Toagood consideration, the value ofS~~ thenumber ofpulses perscan on. 
 £  PL  4HE FACTOR . SHOWS THAT EACH ELEMENT IS ENERGIZED WITH  . OF THE UNITY  INPUT  POWER .ORMALIZING THE GAIN TO UNITY AT BROADSIDE  P       GIVES THE PATTERN   %.S .SA SIN;   SIN = SIN;   SIN =PP P PL PL     %AP   GIVES THE RADIATION PATTERN FOR ISOTROPIC RADIATORS AND IS KNOWN AS THE  ARRAY  FACTOR )T IS SHOWN IN &IGURE  FOR  .    4HIS PATTERN IS REPETITIVE  AND THE  LOCATIONS OF THE ADJACENT GRATING LOBES AT ANGLES  P  AND P  ARE SEPARATED BY  O SK    SIN P   
 It also allows the antenna to be tested in either role (Sec. 6.10). Examples of nonreciprocal radar antennas are phased arrays using nonreciprocal ferrite components, active arrays with amplifiers in the transmit/receive (TfR) modules, and height finding antennas for 3D (range, azimuth, and elevation) radars. 
 14.3. Direct-driven Alternators.-Since all power isultimately derived from the rotation ofthe aircraft engine, fewer devices that can cause trouble are required ifmechanical rotation isused directly to drive analternator. Adirect-driven alternator will normally furnish alternating current whose frequency varies with engine speed. 
 SEC. 3.10] COMPOUND TARGETS 81 effect onthereceived power ofthevariation ofillumination foravertical rectangular sheet and uses the formula thus obtained asadefinition of cross section. 3.10. 
 It is usually desirable to keep W1 in the region from about 8 to 50. Thus the unambiguous range of a two-PRF system is seen to be rather limited, whereas three PRFs give much larger ranges. Some of the consid- erations influencing the choice of W1 to this range are as follows:Item Ranging parameters: Yn1 > m2 > m3 Number of range-gated channels PRFs f*i JR2 (jR3 > JR2 ^* JRl ~ JRmIn) /* Unambiguous range (Rmax) Transmitter duty cycle, d Ratio of highest and lowest PRFTwo-PRF /Wj, m2 /W1-I 1//W1T8 Um2T5 ™2cl2fRl T,//?2 In1Im2Three-PRF /Wj, m2, m$ Wj — 1 1//Tl1T8 1//W2T8 1//W3T8 m2m3c/2fm T,//?3 ml/m3GATES GATE 2 GATE 1 TRANSMITACTIVE RECEIVETIME TRANSMITTIMERECEIVER RECOVERYTIME BLANKED RECEIVE TIME . 
 AGC (Automatic Gain Control).  To maintain a stable closed-loop servosystem for  angle tracking, the radar must maintain essentially constant loop gain independent of  target echo size and range. The problem is that monopulse difference signals from the  antenna are proportional to both the angle displacement of the target from the antenna axis  and the echo signal amplitude. 
 Image with random crop. If we control our crop frame to make sure that the main parts of the pictures haven’t been cut, as shown in Figure 7, it should be noticed that these pictures can be seen as one image and its translations. This method may have good performance in some simple models, which can extract most of the features of the images by training with that data. 
 Figure 9.7shows how well such apattern isrealized inpractice, with anantenna 12in.inheight (shown inFig. 9.8) used atthe 3-cm band. Inthis polar diagram the square root ofthepower isplotted rather than thepower itself, since the desired distribution isthen given byastraight line asshown. 
 2AO ,OWER "OUND #54 #ELL 5NDER 4EST #7 #ONTINUOUS 7AVE $!# $IGITAL 
 7.27  Analytical Techniques  ........................................  7.29 Nonisolating F eeds  ............................................  7.30  Mutual Coupling and Surface Waves  ................. 
 GENERATION -4$ )) PROCESSOR  IS SHOWN IN &IGURE  &)'52%  3UBCLUTTER VISIBILITY COMPARISON BETWEEN THREE 
 (Fl.orn  Guttn and East," Quart. J. Roy. 
 C. Hanson: Experiments on the Radar Backscatter of  Snow, IEEE Tratts.. vol. 
 To achieve a –40-dB Taylor compressed pulse response, for example, the fre - quency-versus-time (frequency modulation) function of a nonsymmetrical NLFM  waveform of bandwidth B is14  f t Bt TKnt Tn n( ) sin = +   =∑2 17π (8.14) FIGURE   8. 9 Symmetrical and nonsymmetrical nonlinear-FM waveforms ch08.indd   12 12/20/07   12:49:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 These signals are then multiplied FIGURE 25.24  NCO block diagram REG+TUNING WORDn+ + nPHASE ACCUMULA TOR MSBsm SINE LOOK-UP MEMOR YPHASE TO AMPLITUDE CONVER TER REG SAMPLE CLOCKk TO DAC CLEAR FIGURE 25.2 5 Digital upconverter (DUC)LPF LPF NCO 25 MHz SINE WAVE–SINCOS100 MHz CLOCK50 50I Q2 MCSPS DUCDAC IF 1414 SUMBPF ch25.indd   21 12/20/07   1:40:25 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 
 This isparticularly true when theloading isonone side only, sothat this arrangement isordinarily used only invery wideband ampli- fiers (15Me/see orover). Another means ofachieving large bandwidth isbyusing stagger- tuned circuits. 1Consider two cascaded single-tuned circuits ofthetype previously described, choosing theload resistors sothat each hasaband- width of4Me/see asshown inFig. 
 Blass, “The multi-directional antenna: a new approach to stacked beams,” in Proc. IRE Conv .,  vol. 8, pt. 
 Barrios, “A Terrain Parabolic Equation Model for Propagation in the Troposphere,” IEEE  Transactions on Antennas and Propagation , vol. 42, no. 1, pp.90–98, January 1994. 
 15 20.  5. Ridenour. 
 A change  in frequency gives rise to grating lobes rather than shifts of the beam position. This can  be seen from Figure 13.27. The subarray pattern is shown at the design frequency f0 and  is seen to have a null at the position of the grating lobe. 
 (/?) Feed de- tail. FIG. 6.18 Low-sidelobe reflector using an extended feed. 
 15.41  15.11 Radar System Stability and A/D Quantization  Requirements  .........................................................  15.45  System Instabilit ies  ............................................  15.45  Effect of Quantization Noise on Improvement  Factor  .............................................................. 
 Forpurposes ofcomparison, thenonnuctuating crosssectionwillbccalledcasi.'5. Acomparison ofthesefivemodelsforafalse-alarm number IIf=108isshowninFig.2.22 for11=10hitsintegrated. Whenthedetection probability islarge,allfourcasesinwhichthe targetcrosssectionisnotconstant requiregreatersignal-to-noise ratiothantheconstant cross sectionofcase5.Forexample, ifthedesiredprobability ofdetection were0.95,asignal-to­ noiscratioof6.2dB/puIsI..' isnecessary ifthetargetcrosssectionwereconstant (case5),butif thetargetcrosssectionfluctuated withaRayleigh distribution andwerescan-to-scan uncor­ related(caseI),thesignal-to-noise ratiowouldhavetobe16.8dB/pulse. 
 The antenna may also be fed in the manner shown in Fig. 7.9~. This is an example of a  front feed. 
 42°21’N, 83001 ‘TV, the absorption ofenergy bywater vapor becomes animportant factor limiting the maximum range ofaradar setat1.25 cm (see Sec. 2.15). Even strong signals from large cities are attenuated below noise level ifthe cities are much beyond the maximum range forground return. 
 &-  &- 
 The Cassegrain principle is widely used in telescope design to obtain high magnification with a  physically short telescope and allow a convenient rear location for the observer. Its application  to microwave reflector antennas permits a reduction in the axial dimension of the antenna.just  as in optics. But more importantly it eliminates the need for long transmission lines and allows  greater flexibility in what can be placed at the focus of the antenna. 
 33. Whicker. L. 
 The high prf, although it gives  unambiguous doppler, usually results in ambiguous range. But more important, a pulse radar  with ambiguous prf can result in lost targets. If the transmitter is pulsed just when the ground  echo arrives back at the radar, it will not be detected. 
 RADAR RECEIVERS  6.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 6.3 BANDWIDTH CONSIDERATIONS Definitions.  The instantaneous bandwidth of a component is the frequency band  over which the component can simultaneously process two or more signals to within a  specified accuracy. When the term instantaneous bandwidth  is used as a radar receiver  parameter, it refers to the resulting bandwidth set by the combination of RF, IF, video,  and digital filtering that occurs within the receiver. 
 It does not  matter whether the distribution is produced by a reflector antenna, a lens, or an array.  Onedimensional aperture distribution Perhaps the simplest aperture distribution to conceive  is the uniform, or rectangular, distribution. The uniform distribution is constant over the  aperture extending from -a12 to +a12 and zero outside. 
 PLANE ERROR SENSING AND COMBINED 4%  AND 4- MODES FOR  % 
 RENT PULSE IS PASSED THROUGH EACH BIT  AND THE FERRITE TOROID IS SATURATED 7HEN THE  CURRENT IS REMOVED  THE FERRITE TOROID IS SAID TO BE LATCHED AND RETAINS ITS MAGNETIZATION  OWING TO ITS HYSTERESIS PROPERTIES )F THE CURRENT IS IN A FORWARD DIRECTION  THE FER 
 The latter is the form of ttrrbulent effect that aircraft encounter at the higher  510INTRODUCTION TORADAR SYSTEMS 19.5HZ.97Thewing-beat frequency finhertzandthelengthIofthewinginmillimeters are found98toberelatedbyfio.827=572.ThetermbirdactilJitymodulation (BAM)hasbeenapplied tothedistinctive waveforms obtained frombirds.92Thespectral components oflheBAM patternofabirdinflightaresaidtoberemarkably stable97andsuitedfordetamining identity. Insects. I20Eventhoughtheyaresmall,insectsarereadilydetected byradar,andinsufficienl numbers canclutterthedisplayandreducethecapability ofaradartodetectdesiredtargetsA radarcrosssectionof0.1cm2,whichmightcorrespond toaninsectthesizeofahousetly atKg band(8.6cmwavelength),99 canbedetected atarangeofabout11nmibyaradarcapableof seeinga I m2targetat200nmi.Evenmodestinsectconcentrations (oneinsectin104m.J)can causeangelactivitywhichcanbeclassedasmoderate.loo AtX.band,radarcrosssectionmeasurements ofavarietyofinsectsrangC)from 0.02to 9.6cm2withlongitudinal polarization, andfrom0.01to0.96cm2fortransverse polarization.lolAdesertlocustl02orahoneybeelOImighthaveacrossseclionofaboutIcml atXband.AtSbandthecrosssectionofacabbage loopermothisabout2x10-~cml,and foranadultfieldcricketitis0.1cm2.103Thecrosssection ofinsectsbdowXbandis approximately proportional tothefourth-power ofthefrequency. 
 W-hen themarker onthe32jO00-yd tube isput over the signal echo tobetracked, the2000-yd tube displays arange interval 1000 ydoneither side ofthetarget range. The marker onthe 2000-yd tube can then besetexactly onthe leading edge ofthetarget signal. When this adjustment ismade the marker iskept inregister with the desired signal, and continuous target-range information issent tothe computer. 
 10.8CONSTANT-FALSE-ALARM-RATE (CFAR) RECEIVER Thethreshold attheoutputofaradarreceiver, asdiscussed inSec.2.5,ischosensoasto achieveadesiredfalst·alarm probability. Thefalse-alarm rateisquitesensitive tothethresh­ oldlevel.Forexample, a 1dBchangeinthethreshold canresultinthreeordersofmagni­ tudechangeinthefalsealarmprobability (Fig.2.5).Itdoesnottakemuch");' adriftinthe receiver gain,achangeinreceivernoise,orthepresence ofexternal noiseorclutterechoesto inundate theradardisplaywithextraneous responses. [fchanges inthefalse-alarm ratearegradual, anoperator viewingadisplaycancompen­ satewithamanualgainadjustment. 
 As a simple example, consider small and uncorrelated phase and amplitude errors on every transmitting and receiving element. From array theory it is well known that the effect of this kind of errors is to add to the sidelobes a uniform power level proportional to the mean square error: /angbracketleft|δFTX|2/angbracketright=σ2 TX/nTX;/angbracketleft|δFRX|2/angbracketright=σ2 RX/nRX. (6) Using these relations to compute the MIMO SideLobe Level it is possible to gather that, in a MIMO array, small and uncorrelated phase and amplitude errors generate a non-uniform SideLobe Level: SLL MIMO/similarequal|FRX|2σ2 TX nTX+|FTX|2σ2 RX nRX. 
 BEAM NOISE JAM 
 POWER 474S GENERALLY SHOW AN APPRECIABLE FALLOFF OF  POWER OUTPUT TOWARD THE BAND EDGES  SO THAT THE RATED BANDWIDTH DEPENDS VERY MUCH ON HOW MUCH POWER FALLOFF CAN BE TOLERATED BY THE SYSTEM. £ä°£ä  2!$!2 (!.$"//+  )F A 474 USING A COUPLED 
 di .. ·,, ., •. ·l,,  Figure 12.13 gives.the antenna.noise.temperature computed for a typical IO-ft-diameter  parabolic reflector operating at 1000 MHz as a function of the antenna elevation angle. 
 If  the receiving and sending antennas are not the same, one then speaks of quasi -monostatic R a- dar if the antennas are close to one another, meaning  € θi≈θS and  € φi≈φS.  For further consi d- eration it is important that σ characterizes the target for only one frequency and one polariz a- tion at given aspect angles  € θi,φi,θS,φS( ) and it doesn’t contain any phase information of the  scattering.  . 
 53, pp. 581-591, June 1965. 17. 
 July. 1964.  110. 
 ATED &OR EXAMPLE  IF MAIN 
 SCALE TARGET MAY BE OBTAINED FROM THE SCALE 
 Thebeam-shape lossconsidered abovewasfor.abeamshapedinoneplaneonly.It appliestoafanbeam,ortoapencilbeamifthetargetpassesthrough itscenter.Ifthetarget passesthrough anyotherpointofthe.pencilbeam,themaximum signalreceivcd willIlOt correspond tothesignalfromthebeamcenter.Thebeam-shape lossisreduced bytheratioof thesquareofthemaximum antenna gainatwhichthepulsesweretransmitted dividedbythe squareoftheantcnna gainatbeamcenter.Theratioinvolves thesquarebecause ofthc two-way transit. Whentherearealargenumberofpulsesperbeamwidthintegrated, thescanning lossis generally takentobe1.6dBforafanbeamscanning inonecoordinate and3.2dRwhen two-coordinate scanning isused.49-Sl Whentheantenna scansrapidlyenoughthatthegainontransmit isnotthesameasthe gainonreceive,anadditional losshastobecomputed, calledthescanningloss.Thetechniquc. TSIE RADAR EQLJATION 59  for computing scanning loss is similar in principle to that for computing beam-shape loss. 
 Basic Configuration. Figure 17.6 shows a representative configuration of a pulse doppler radar utilizing digital signal processing under the control of a central computer. Included are the transmitter suppression circuits, main-beam and sidelobe discrete rejection circuits, and ambiguity resolvers. 
 167  15.5 Antennenarrays ............................................................................................................. 168  15.6 RCS ............................................................................................................................... 168  15.7 Digital Beamforming .................................................................................................... 
 FIGURE 16.2 5 Regressions for vertical-polarization  clutter model for snow: ( a) day and ( b) night. Note the  large differences. Horizontal polarization is similar. 
 TER  WHICH HAS ALSO BEEN WIDELY USED IN RADAR ! QUESTION THAT NATURALLY ARISES IS WHICH 2& POWER SOURCE SHOULD BE USED FOR SOME PARTICULAR RADAR APPLICATION 2ADAR SYSTEM DESIGN USUALLY INVOLVES MAKING CHOICES AMONG THE VARIOUS POSSIBILITIES AVAILABLE 7HEN TRYING TO DETERMINE WHICH 2& POWER SOURCE TO USE  A CHOICE CAN BE MADE BY DOING A SEPARATE SYSTEM DESIGN WITH EACH 2& POWER SOURCE THAT SEEMS PROMISING 4HE DECISION AS TO WHICH TO USE CAN BE BASED ON HOW WELL EACH SYSTEM DESIGN PERFORMS THE DESIRED TASK ACCORDING TO SOME PRE 
 IER 1 ITSA 1 , U.S. Department of  Commerce, 1966. 28. 
 [ 41] investigated the rate and spatial patterns of subsidence in major urban areas in Wuhan city using PS-InSAR method with TerraSAR-X images (October 2009 and August 2010) with 2.0 m×3.3 m (range ×azimuth) spatial resolution. Subsidence rates varied from −63.7 mm/yr to 17.5 mm/yr, and HK is the largest subsidence area. Costantini et al. 
 TRACING THROUGH A MODEL IONOSPHERE  SHOWING THE VARIATION OF THE RADAR FOOTPRINT  WITH CARRIER FREQUENCY 4HE CONTOURS MAP THE PLASMA FREQUENCY OR ELECTRON DENSITY.   (& /6%2 
 9.4] NONSCANNING ANTENNAS 277 perpendicular polarization, posts scatter theradiation badly and arenot generally used; but fortunately the wavefronts are not disturbed by gentle variations inthe spacing ofthe sheets. Both polarizations are used inpractice. FIG.9,9.— Photograph ofPPIscope of3-cm airborne radar: Cape Codarea. 
 ( 1.9)] may be written with the propagation  factor 17 included to illustrate the effect of the plane earth:  for small angles  .J ( 12.8)  The received signal power for targets at low angles (on the lower side of the first lobe) varies as  the eighth power of the range instead of the more usual fourth power. This phenomenon has  been experimentally verified for ship targets at short ranges where the plane-earth approxima­ tion has some validity.1 Another difference between Eq. (12.8) and the normal radar equation  is the factor G/)., which appears in place of the factor Gk  The analysis in this section is based on many simplifying assumptions; therefore care  should be exercised in adapting the results and conclusions to more realistic situations. 
 Ifthejammer isradiating, HOJisgenerally abetter guidance technique thanisradarguidance. Stand-ofT jammers arealsosubjecttodirectattack hyinterceptor aircraft. Increasing theradarenergyinthedirection ofthejammer inthehopeofincreasing the radarechopowerabovethejamming noiseiscalledbumthrough. 
 As mentioned  earlier, the SNR of a sampled signal can be increased by filtering to eliminate noise  in parts of the spectrum that are otherwise unused. However, the spurs generated  by an ADC may lie in the band of interest, where filtering would be inappropriate.  Therefore, spurs lower than the unfiltered noise level can become relatively signifi - cant after ADC noise is reduced through filtering. 
 A cascaded digitally switched phase shifter with four phase bits  capable of switching in or out lengths ofline equal to ..l/16, ..l/8 . ..l/4, and ..l/2 yields a phase shift  with a quantization of l/16. just as the parallel line shifter with 16 lengths of line described  above. 
 Large clutter energy is desired  since the "clutter" is the target.  The detection a( terrain featllres such as hills and mountains ahead of an aircraft to warn of  approaching high ground (terrain cwoida11ce) or to allow the aircraft to follow the contour  oft he land (terrai11_followi11g ).  Mapping. 
 The most common approach [ 1–3] imposes a weighting on the signal spectrum, such as the Taylor and Hamming windows, but such methods tend to widen the mainlobe. Another method, known as spatially variant apodization (SVA) [ 4,5], and its modiﬁed versions [ 6–9], can reduce the sidelobes without degrading mainlobe resolution. However, nonlinear apodization modiﬁes the statistical distribution of the pixel intensities, thushindering the extraction of information from homogeneous regions [ 10]. 
 The 5 rpm rotation rate of the antenna corresponds to a 12-second interval between  target observations (scan time). This is about the longest interval that can usually be tolerated  between observations of aircraft targets. A high rotation rate is needed for good target track­ ing. 
 SQUARED BEFORE APPLYING TOOLS  SUCH AS SPECKLE FILTERS  THAT ARE DESIGNED FOR  R    DIMENSIONALITY 3ECOND   R   IMPLIES THAT THE DATA ARE CALIBRATED  NOT  ONLY WITH RESPECT TO THE RADIOMETRIC PARAMETERS OF THE RADAR AND PROCESSOR  BUT ALSO WITH RESPECT TO THE LOCAL INCIDENT ANGLE AT THE PIXEL LOCATION  X Y  !LTHOUGH DATA FROM  %23 
 Also, interactions may occur between the scatterers which  affect the resultant cross section.  An example of the cross section as a function of aspect angle for a propeller-driven  Rodar Figure 2.14 Geometry or the two-scatterer complex target. r \ \'\. 
      
 4.23, with the total response  covering the region from f= 0 to f = 1/T =fp· Each filter has a bandwidth of 2/NT as  measured between the first nulls. Because of the sampled nature of the signals, the remainder of  the frequency band is also covered with similar response, but with ambiguity. A bank of filters,  as in Fig. 
 36.)  41. 1)yer. F. 
 BAND 3"2 IMAGERY OF THE %ARTHS SURFACE 4HE TECHNOLOGY BEHIND THIS AND RELATED 2USSIAN SYSTEMS CONTINUED TO BE DEVELOPED  CULMINATING IN THE +ONDOR 
 TER OR 2& POWER AMPLIFIER AND THE ANTENNA RADIATOR  WHICH CAN INCLUDE LOSSES FROM  CONNECTORS  CIRCULATORS  AND RADIATING ELEMENTS 2ADOME ,OSS -OST RADARS REQUIRE A RADOME TO PROTECT THE ANTENNA FROM ENVIRON 
 Henceitdoesnotpreserve theshapeoftheinputwaveform. (Thereisnoreasonto wishtopreserve theshapeofthereceived waveform solongastheoutputsignal-to-noise ratio ismaximized.) LetliSreturntothereceiveroutputasrepresented inFig.2.1.Athreshold levelisestab­ lished.asshownbythedashedline.Atargetissaidtobedetected iftheenvelope crossesthe threshold. IfthesignalislargesuchasatA,itisnotdifficult todecidethatatargetispresent. 
 The closer the spacing, the less will be  tlie index of refractiori arid tlic tliiritier will be the ieris. However, the spacing, and therefore the  index of refractiori. cannot bc made arbitrarily small since the reflection from the interface  between the lens arid air will increase just as in the case of the solid-dielectric lenses. 
 - 
 This choice permits the antenna to have a relatively small vertical dimension. The AN/FPS 118 radar module uses a nominal 7.5° transmitter footprint filled with five receive beams; this combination is stepped as a surveillance barrier within a potential coverage area 500 to 1800 nmi in distance by 60° in width. The antennas and power amplifiers used in HF broadcast station service have much in common with an HF radar transmitter-antenna combination; that is, the broadcast-service aim is to obtain a specified level of illumination over some se- lected area. 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 within the tracking gates and the statistical distance between the detection and track. If  the detection is outside the track gate, the statistical distance is set to infinity. 
 TIONS v )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS   VOL !%3 
 J.E.: The AN/FPS-85 Radar System, Proc. IEEE. vol. 
 FORM 4HOSE DESIRING MORE INFORMATION MIGHT EXAMINE #HAPTER  IN , 3IVANS BOOK ON TRANSMITTERS   THE CHAPTER BY 4 ! 7EIL IN THE SECOND EDITION OF  2ADAR (ANDBOOK   THE #ONFERENCE 2ECORDS OF THE )NTERNATIONAL 0OWER -ODULATOR 3YMPOSIA  AND THE #ONFERENCE 0ROCEEDINGS OF THE )%%% 0ULSE 0OWER #ONFERENCES 4HE TYPE OF TUBE DETERMINES  TO SOME EXTENT  THE TYPE OF MODULATOR ! MODULA 
 131. R. K. 
 12.3] SPECIAL PROBLEMS INRADAR RECEIVERS 441 Ifelevation angle issubstituted forazimuth, the device becomes an RHI. Usually, inthis case, the gain ofthe vertical amplifier ismade greater than that ofthehorizontal, sothat thedisplay is“stretched” in the vertical direction. Since direct-coupled push-pull sweep amplifiers areusually used, they can bebiased insuch away astoproduce the “off-centering” shown. 
 McCandless, “Synthetic aperture radar imaging systems,”  IEEE AES Magazine , pp. 15−23, November 1995. 10. 
   0 ;ONE GIVEN SIDELOBE    D"=       0 ;ONE GIVEN SIDELOBE    D"=       0 ;ONE GIVEN SIDELOBE    D"=  4HAT IS  TO KEEP ALL  SIDELOBES BELOW  
 A reduction of the minimal received power of the receiver gets an increase of the  maximum range.     For every receiver there is a certain receiving  power as of which the receiver can work at all.  This smallest wor kable received power is  frequently often called MDS - Minimum  Discernible Signal or Minimum Detectable Signal  in radar technology. 
  
 Using Eq. 12.14 and Eq. 12.15 leads  to the simple expression for blockage loss typically found in the literature5:  E ED D E Eb mb m b m= = −  = −2 1 12 2 2 BlockageLoss 2 22 22D Db m    (12.15) where Db and Dm are the diameter of the blockage and reflector, respectively. 
 OVER 
 Target motion can  cause an error in range equal to v, T0, where v, is the relative velocity and T0 is the observation  time. A.t short ranges the residual path error can also result in a significant error unless  compensated for. The residual path error is the error caused by delays in the circuitry and  transmission lines. 
 22, 1983. 23. Walker, J. 
 0 (DEGREES) FIG. 6.10 Pillbox structure used to test a low-sidelobe parabolic cyl- inder and its measured pattern. (Courtesy Ronald Fante, Rome Air Development Center.} a linear array for low-sidelobe azimuth patterns and shaped in height for elevation coverage. 
 When the aircraft is at B, the center of the side-looking beam points to the target Pi, the beam-width of side-looking beam is θBW2, and the Doppler bandwidth of side-looking beam is BW2=2v λ/bracketleftbigg sin(θBW2 2)−sin(θBW2 2)/bracketrightbigg ≈2v λθBW2 (2) 11. Sensors 2019 ,19, 1701 Finally, the echo data of target Pifrom backward -looking beam is obtained. When the aircraft is atC, the center of the backward-looking beam points to the target Pi, the backward-looking beam-width isθBW3, and the Doppler bandwidth of backward-looking beam is BW3=2v λ/bracketleftbigg sin(−θ+θBW3 2)−sin(−θ−θBW3 2)/bracketrightbigg ≈2v λcosθ·θBW3 (3) The beam-width of the phased array antenna is θBW=θ/prime BW/ cos θ, where θ/prime BWis the beam-width of the side-looking beam, and substitute it into Equations (1)–(3). 
 However, if  the displacement is random, say caused by vibration, the beam pointing error can be  a problem. The reflector beam will be steered by q radians if the feed is displaced off  axis by an amount e  q = arctan(e /f), radians  (12.21) where f is the focal length. So if the lateral feed displacement error is e, the beam  pointing error, ∆q, is  ∆θε ε=+/ ( /)f f 12, radians  (12.22) Strut Blockage. 
 RONMENT OF INTEREST BE COLLECTED AND ANALYZED AND THAT VARIOUS DETECTION PROCESSES BE SIMULATED ON A COMPUTER AND TESTED AGAINST THE RECORDED DATA &)'52%   2ESOLUTION CAPABILITY OF A LOG DETECTOR THAT USED HALF OF THE REFERENCES CELLS WITH   LOWER MEAN AFTER ' 6 4RUNK Ú )%%%   &)'52%   0ROBABILITY OF RESOLUTION AS A FUNCTION OF RANGE SEPARATION PROBABILITY OF FALSE ALARM   IS  SAMPLING RATE  $2    SAMPLES PER PULSE WIDTH TARGET STRENGTHS  NONFLUCTUATING  !    !     D" PHASE DIFFERENCES           AND  AFTER ' 6 4RUNK Ú )%%%  . Ç°ÓÓ  2!$!2 (!.$"//+  -ANY MODERN RADARS USE COHERENT PROCESSING TO REMOVE CLUTTER &OR THE PURPOSE OF  APPLYING THE PREVIOUS DISCUSSIONS ON NONCOHERENT PROCESSING TO COHERENT PROCESSING   THE INTEGRATED OUTPUT IN A RANGE 
 Its degree of applicability, however, is not clear.  It is not unusual to find no account of the operator loss being taken in the radar equation.  This is probably justified when operators are alert, motivated, and well trained. 
 79. Knittel. G. 
 J. M. Headrick and M. 
 There are also no restrictions on the spacing between the elements as long as the coupling coefficients are measured for the spacing and environment to be used. A considerable simplification is obtained by assuming that each of the ele- ments sees the same environment and has the same voltage excitation. Then \Vpq\l\Vmn\ will always be unity, and the reflection coefficient at element mn is merely the sum of the mutual-coupling coefficients with the excitation phase at each element taken into account: r = V C J(m-p)TX5J(n-q)Tys 1 mn /j ^mfiipq*- *•- attpq where ^m~p^Txs and e^n~q)Tys give the relative phase excitations in the x and y di- rections of the pqth element with respect to the mnth element. 
   PP n    7 $ "LAIR AND 9 "AR 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 22.6  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 Nowadays, it normally involves sophisticated adaptive thresholding techniques, which  are discussed in Section 22.4. 
 Cross-section fluctuations. In the discussion of radar cross section in Sec. 2.8, it was stated that  the angular pattern of the cross section of targets has a many-lobed structure whose spacings  depend on the size and nature of the target. 
 The results are shown in Fig. 8.2, where a normalized standard devia- tion is plotted against the midbeam S/N. This result holds for a moderate or large number of pulses integrated, and the optimal estimate involves finding the location where the correlation of the returned signal and the derivative of the antenna pattern is zero. 
 6.14). InMay 1937 the Air Corps requested’ the development ofa“long-range detector and tracker. ”One laboratory version oftheresulting equipment was demonstrated inNovember 1939 and showed arange ofmore than 100miles onbombers. 
 NOISE RATIO WITH A GUARD CHANNEL &)'52%  -AIN AND GUARD ANTENNA PATTERNS . {°ÓÓ  2!$!2 (!.$"//+  " IS SMALL FOR A TARGET IN THE MAIN BEAM AND LARGE   D" OR SO  FOR A TARGET AT THE  SIDELOBE PEAKS )N THE EXAMPLE SHOWN  THERE IS A  D" DETECTABILITY LOSS DUE TO  THE GUARD BLANKING FOR TARGETS IN THE MAIN BEAM )DEALLY  THE GUARD ANTENNA GAIN PATTERN EXCEEDS THAT OF THE MAIN ANTENNA AT ALL ANGLES  IN SPACE EXCEPT FOR THE MAIN BEAM  TO MINIMIZE DETECTIONS THROUGH THE SIDELOBES )F NOT  HOWEVER  AS ILLUSTRATED IN &IGURE  AND &IGURE   RETURNS THROUGH THE SIDELOBE PEAKS OF THE MAIN PATTERN ABOVE THE GUARD PATTERN HAVE A SIGNIFICANT PROBABILITY OF DETECTION IN THE MAIN CHANNEL AND WOULD REPRESENT FALSE DETECTIONS 0OSTDETECTION 34#  )N THE AMBIGUITY RESOLUTION  AS THE OUTPUT RETURNS ARE  RANGE 
 J.: Frequency Insensitive Phase-Shift Networks and their use in a Wide-Bandwidth  Butler Matrix, Electronics Letters, vol. 5, No. 20, pp. 
 TUDE AND PHASE SPECIFIED BY THE MAGNITUDE AND ANGLE OF THE COMPLEX AMPLITUDE 4HE LATTER RELATIONSHIP IS SO MUCH A PART OF THE ENGINEERING CULTURE THAT THE TERMS  AMPLITUDE  AND PHASE ARE COMMONLY  IF IMPRECISELY  USED TO REFER TO THE MAGNITUDE AND ANGLE OF A  COMPLEX SIGNAL AT AN INSTANT IN TIME 4HE FOLLOWING FIGURES ILLUSTRATE THE ORIGIN OF THE .YQUIST RATE )MAGINE THAT A REAL  SIGNAL WITH A  LOWPASS SIGNAL SPECTRUM OF TWO 
 FLFCTRONICALLY STF.f.Rf.D PUASF.D ARRAY ANTENNA IN RADAR 327  Table 8.2 Example of priorities for a tactical system 121  0 Dedicated mode  Burn through  Target definition  Special test  Engagements  Engaged hostile  Own missile  Preen gaged hostile  1 Time-critical Previously scheduled events  that capture radar ror  long periods of time  High-priority transition  High-priority confirmation  Horizon search  Special request  Burn through  Target definition  Special ,cans  Target acquisition  4 High-priority tracks  Confirmed hostile  Assumed hostile  Unevaluated  Controlled friendly  Confirmation  Track transition  5 Low-priority track  Assumed friendly  Confirmed friendly  Above-horizon search  All coverages  Special test  7 Simulation, diagnostics, and dummies  Table courtesy RCA. Inc.  The computer must be capable of responding to the immediate demands of high-priority  tasks withojut throwing away the results of partially completed lower-priority tasks. 
 The input RF signal at fre - quency fR is frequency shifted or modulated by the LO signal at frequency fL. Balanced  mixers are used to minimize conversion loss and unwanted spurious responses. In  active mixers, modulation is performed using transistors, and in passive mixers, the  modulation is performed using Schottky-barrier diodes or other solid-state devices  (e.g., MESFET) where increased dynamic range is required. 
 The linear  FM signal has a phase that varies as tZ (t = time), and the cross-range signai has a phase that  varies as .uZ (.u = distance along the ground track). Just as the phase history >f the cross-range  signal records on film as a Fresnel zone-plate, which then has a focusing action when iliu-  minated by coherent light, so does the signal of the linear FM waveform also record as a  Fresnel zone-plale. The range and the cross-range recorded signals may be treated as orthog-  onal aspects of a single two-dimensional filtering operation. 
 HORN AND  AS SUCH  ARE ESPECIALLY USEFUL FOR TRACKING APPLICATIONS -ONOPULSE &EEDS n -ONOPULSE IS FREQUENTLY  USED IN RADAR TRACKING AND SURVEILLANCE SYSTEMS TO EITHER KEEP THE BEAM POINTED ON THE TARGET TRACKING  OR TO ACCURATELY MEASURE THE ANGLE TO THE TARGET SUR 
 In practice, most radars operate at microwave frequencies, but there are notable exceptions. Radar engineers use letter designations, as shown in Table 1.1, to denote the general frequency band at which a radar operates. These letter bands are univer- sally used in radar. 
 Geophys. Res. , vol. 
 Thebandoccupied bythesignalisB,andthecarrierfrequency isfo.Thisexpression forthe doppler-tQlerant waveform isdifficult tointerpret asitstands,butifthenatural-log factoris expanded inaseries,Eq.(11.55)becomes (11.56) Whentermsgreaterthanthefirsttwocanbeneglected (whichapplieswhen2rr.B2t3<{3foT2), Eq.(11.56)reduces totheclassical linearFMwaveform. ThusthelinearFM,orchirp,pulse­ compression waveform isapractical approximation tothetheoretical doppler-tolerant waveform. Differentiating, withrespecttotime,theargument ofEq.(11.55), thefrequency of thedoppler-tolerant waveform isfoundtobe2rr.f'5T/(foT-Bt).Inverting toobtainthe period, itcanbeseenthatthedoppler-tolerant waveform isonewithalinearperiod modulation. 
 CALLED  SKIP OR DEAD ZONE WITHIN  WHICH THE %ARTHS SURFACE IS NOT ILLUMINATED "EYOND THIS SKIP ZONE  ENERGY IS RETURNED TO  THE %ARTH  REACHING A MAXIMUM RANGE WHEN THE RAYS LEAVING THE ANTENNA ARE HORIZONTAL 5SEFUL RANGE COVERAGE WILL LIE BETWEEN THESE LIMITS  WHICH DEFINE THE  ONE 
 74 Unconventional transmission lines have also been  developed.95 97  Thus the advances in components made in the past as well as technology evident to either  side of the millimeter region give reason to believe that Nature has not ruled out attainment or  adequate capabilities at millimeter wavelengths.  Unfortunately, the limited availability of suitable millimeter wave components is not the  major reason for the lack of significant applications. The problem with millimeter wavelengths  is that several of its favorable characteristics are also factors that limit its performance; in  particular, the small antenna size and the consequences of its characteristic wavelengths. 
 Any use is subject to the Terms of Use as given at the website. Radar Receivers. 6.42  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 selecting every Dth sample. Provided the filter response H(w) has sufficient rejection  for frequencies | | /w≥πD, there will be negligible aliasing and loss of information in  the decimation process.FIGURE 6.17  Digital downconversion architectureI(m) A/D x(t)~x(n) xI(n)h(n) D cos(w0n)sin(w0n) h(n) DFIR Filter with  Impulse Response h(n) y(m) = I(m) + jQ(m) Q(m)Decimation by  Factor D  y(m) = x(mD)^ x(n)^ FIGURE 6.18  Digital downconversion spectra B F0−F0F w0w~X(w)X(F) −w0 p −p 2p − 2w0w p wX(w) Y(w)p w p−p −p −p(a) (b) (c) (d) (e)X(w) ^ ch06.indd   42 12/17/07   2:04:13 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 If the envelope of the receiver output exceeds a pre-established threshold,  a signal is said to be present. The purpose of the threshold is to divide the output into a region  of no detection and a region of detection; or in other words, the threshold detector allows a  choice between one of two hypotheses. One hypothesis is that the receiver output is due to  noise alone; the other is that the output is due to signal-plus-noise. 
 25–36, 1989. ch16.indd   56 12/19/07   4:56:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 31. H. Masuko, K. 
 Herice the false-alarm  probability of any one pulse must be small ( < 10-6) if false-alarm times greater than 1 s are to  be obtained.  The specification of a tolerable false-alarm time usually follows from the requirements  desired by the customer and depends on the nature of the radar application. The exponential  relatjonship between the false-alarm time Tra and the threshold level Vr results in the false­ alarm time being sensitive to variations or instabilities in the threshold level. 
 This time delay, which istheobserved quantity, may then beregarded asameasure ofthe rate ofchange ofphase with frequency ofthereturned components. 5.4. Class ofSystems Considered.—In this chapter wewill consider that class ofsystems inwhich the modulation issuch that energy is emitted all, ornearly all,the time. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas.  REFLECTOR ANTENNAS  12.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 where l is the wavelength. 
 -(Z 6#8/  WHICH IS  IN TURN  LOCKED TO '03 TIMING SIGNALS 3YNCHRONIZATION AND OTHER HOUSEKEEPING DATA ARE SENT OVER TELEPHONE LINES 3IGNAL AND DATA PROCESSING IS 0# 
 106–116,  1961. 43. L. 
 Range-Limited Clutter Cell Area. The range-limited clutter cell area (Ac)r has been evaluated at small grazing angles for all geometries of interest. At small grazing angles and at large range sums (RT + RR » L), a two-dimensional approximation to (Ac)r is a parallelogram shown as the double-hatched area in Fig. 
 The goal of ECCM is to raise the cost of ECM. to the point  where it is prohibitive. The effect of ECM on a single radar can seldom be considered in  isolation since it is seldom that a single radar acts as an entity in itself. 
 Lasers can produce usable power at optical frequencies and in the  infrared region of the spectrum. They can utilize wide bandwidth (very short pulses)  and can have very narrow beamwidths. Antenna apertures, however, are much smaller  than at microwaves. 
 FED PARABOLIC DISH ANTENNAS WITH FOCAL 
 12.5a. (Variations of the refractive index in the  tiorizontal plarie may also exist, but they do not materially alter the bending.)  Refractio~i of radar waves in the atmosphere is atialogous to bending of light rays by an  optical prism. The patli of the radar waves through the atmosphere may be plotted using  ray-tracing techtliqucs, provided the variation of refractive index is known. 
 Remote Sens. 2016 ,54, 4806–4817. [ CrossRef ] 30. 
 Providence, R.I.. 1944. Published by University of California  Press. 
 The vertical deflection of the CRT is in synchronism with the range  sweep of the radar. A lens focuses the CRT output on a moving strip of film whose rate of  travel is proportional to the speed of the vehicle carrying the radar. The vertical dimension on  the film represents tlie range and the horizontal dimension represents the cross-range, cr  along-track coordinate. 
 M. Roth: Ferrite Phase Shifters in Rectangular Waveguide. J. 
 The Radar Imaging Satellite, or RISAT, is India’s first space-based  SAR,27 following extensive programs in optical remote sensing satellites and airborne  imaging radar development. RISAT’s deployable antenna (6 m by 2 m) is an active  phased array comprised of 288 C-band (5.35 Ghz) TR modules, each capable of 10 W  peak power. The average output power (200 W) requires an average input dc power  of 3.1 kW. 
 An A-scope with a segment of the time base expanded near the blip for greater accuracy in  distanCf measurement.  RH I, or Range-Height Indicator. An intensity modulated display with height (altitude) as the vertical axis  and range as the horizontal axis. 
 Absolute target location  (relative to earth coordinates) will include the accuracy of the survey of the antenna  pedestal site. Phased array instrumentation radar, such as the Multi-object Tracking Radar  (MOTR), provide electronic beam movement over a limited sector of about  ± 45o to  approximately ± 60o plus mechanical movement of the antenna to move the coverage  sector.16–19 The output will be mechanical shaft positions locating the normal to the  array plus digital angle information from the electronic beam scan for each tar get. 9.8 TARGET-CAUSED ERRORS (TARGET NOISE) Radar tracking of targets is performed by use of the echo signal reflected from a target  illuminated by the radar transmit pulse. 
 However, with proper waveform design the doppler/bandwidth ratio can usually be minimized so that good doppler response is obtained over the target velocities of interest. The range-doppler response, or ambiguity diagram, over this velocity region then approximates the autocorrelation function. Barker Codes. 
   -4) 2!$!2  Ó°{x LIMITATION IS PREDOMINANT &OR TWO 
 STATE MODULE RELIABILITY HAS PROVEN TO BE EVEN BETTER THAN THE -), 
 LEVEL INSTRUMENT AND MISSION DESIGN 3ATELLITE ALTIMETERS DEDICATED TO DETERMINING THE OCEANS LARGE 
 02& WAVEFORMS INTERLEAVED WITH MEDIUM 
 The above expressions in Table 21.4 assume that the current source contacts the  dielectric, whereas a more general condition is when the antenna is just above the  dielectric. A significant practical problem for many applications is the need to main - tain sufficient spacing to avoid mechanical damage to the antenna. It can, therefore, be  appreciated that the effect of changes in distance between the antenna and half space is  to cause significant variation in the resultant radiation patterns in the dielectric. 
 The necessity ofproviding for avarying pulser load influences rectifier and power-supply design. Itisfrequently desirable tochange therepetition rate ofthepulser. This change iseasy inprinciple, but in 1RLReport No.S09, Sept. 
 I Eli (Londori) Conf. Puhl. no. 
 POWER 5(& KLYSTRON THAT HAD A  -7 PEAK POWER   -(Z  D" BANDWIDTH   D" GAIN  AND AN AVERAGE POWER OF  K7 AT A DUTY CYCLE OF  AND A  §S PULSE WIDTH 4HE 6! 
 The re- quirement for good cross-polarization design practice in a radar antenna system extends to any auxiliary ECCM antennas as well. If their cross-polarized gains are high, ECCM techniques such as SLC and SLB may not be effective against cross-polarized noise or repeater jammers.15 In the second use of polarization the radar antenna system purposely receives the cross-polarization component of the radar wave in addition to the copolarized component. The two orthogonally polarized components can be used to discrim- inate the useful target from chaff and jammer on the basis of their different polarizations.20 However, limited benefits (few decibels of cancellation ratio) can be obtained at the expense of a more complex antenna system (consider, for ex- ample, a phased array with radiating elements able to separately receive and pos- sibly transmit the two orthogonal components of a radar wave) and of a duplica- tion of the receiver and signal processing. 
 It results in the center of the doppler spectrum being  shifted, so that the direction as determined from the doppler spectrum will differ from that of  the center of the antenna beam. This is sometimes called the calibration-shift error. This error  can be corrected by lobe switching; that is, by periodically switching the antenna beam a small  amount in they-direction at a 1ow rate (perhaps 20 Hz).55 Two displaced doppler-frequency  spectra are produced at the two antenna positions. 
 wavefront can beused forthepurpose. InFig. 13.18atheadvent ofthe wavefront abruptly changes the potential ofpoint A.Immediately thereafter Cstarts todischarge through R,and pulses oftheshape shown result. 
 425-433, Apr. l, 1947.  46. 
 -00  Therefore we have  2E Rr < -­-No (10.12)  ( 10.13)  ( 10.14)  The frequency-response function which maximizes the peak-signal-to-mean-noise ratio Rr  may be obtained by noting that the equality sign in Eq. ( 10.11) applies when P = kQ, or  H(f) = GaS*(J) exp(-j2efti) (10.15)  where the constant k has been set equal to 1/Ga.  The interesting property of the matched filter is that no matter what the shape of the  input-signal waveform, the maximum ratio of the peak signal power to the mean noise power  is simply twice the energy E contained in the signal divided by the noise power per hertz of  bandwidth N0• The noise power per hertz of bandwidth, N0, is equal to kT0F where k is the  Boltzmann constant, T0 is the standard temperature (290 K), and F is the noise figure. 
 ROLOGICAL APPLICATIONS BECAUSE SHORT PULSE PEAK POWER HAS NOT BEEN A LIMITATION ON  WEATHER RADAR SYSTEM PERFORMANCE +EELER AND &RUSH  HOWEVER  DESCRIBED HOW ATMO 
 Rrldio S(~ic~trc~c~. vol. 1. 
 We are faced with a great blip of  light showing where the transmitter pulse is being sent  out, and a fainter one, or several fainter blips, showing  echoes received back. If the transmitter pulse is very  big it will hide some of our faint, very close echoes. As  the transmitter pulse serves no real purpose here we  can dispense with it, and in many radar systems we do  commonly black-out the blip. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Meteorological Radar. 19.44  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 72. 
 INDUCED JITTER  WHICH MAY EVEN EXCEED POWER 
 #ODED  7AVEFORMS  !  TIME 
 R. Laitig: Study of Iloppler Spectra of Radar Sea Eclio. J. 
 Thomson, and J. J. Campbell: Experimental Results of the  Complex Indicated Angle Technique for Multipath Correction, IEEE Trans., vol. 
 Itistherefore necessary tocause thereturned signals tovary insome manner sothat the variation can bemeasured, rather than toattempt such anabsolute measurement asthat described above. This desired variation iscaused byamodulation process ofsome sort. The word “modulation” isused herein ageneral sense toinclude changes induced bythe target aswell aschanges insignal introduced atthe transmitter. 
 A cos6 sin (*€ sine)„ = 4*— -^-—2 (1U7) where A is the physical area of the plate, e is the angle between its surface normal and the direction to the radar, and € is the length of the plate in the principal plane containing the surface normal and the radar line of sight. A more general physical optics formula is available for the bistatic scattering of a polygonal plate with an arbitrary number of sides.30'31 A rectangular plate has a pair of orthogonal principal planes, and the edge length € in Eq. (11.17) is that lying in the plane of measurement. 
 Bouman and H. W. J. 
 To validate the algorithm, the proposed approach is then tested both on simulated data and on real data images. Focusing results have been carried out on several ERS1/2 raw data images showing the feasibility of the approach. 2.1. 
 19. R. L. 
 The frequency  excursion of the modulation waveform can be adjusted by a servomechanism to maintain the  maximum of the Bessel function at the aircraft's altitude. The frequency translator is not  needed in an airborne doppler navigator since the antenna beam is directed at a depression  angle .:,ther than 90° and a doppler-shifted echo is produced by the motion of the aircraft.  !\latched filter detection. 
 Cantrell, and F. D. Queen, “Modified generalized sign test processor for 2-D  radar,” IEEE Trans ., vol. 
 WAVE %- MODELS THAT CAN BE USED AS SOURCES FOR REFLECTOR AND SCATTER 
 Often this SNR  is not as high as one would expect based on the number of bits used by the A/D   converter. Sometimes the actual performance of an A/D converter is characterized by  an effective number of bits, smaller than the actual number of bits and correspond - ing to the achievable SNR. The SNR of an A/D converter sets an upper limit on the  achievable improvement factor. 
 PULSE  FLUCTUATIONS  M    REFERENCE CELLS   0FA    
 Ducoff Lockheed Martin Corporation (CHAPTER 8) Alfonso Farina SELEX Sistemi Integrati (CHAPTER 24) William G. Fedarko Northrop Grumman Corporation (CHAPTER 4) Joe Frank The Johns Hopkins University Applied Physics Laboratory (CHAPTER 13) Vilhelm Gregers-Hansen Naval Research Laboratory (CHAPTER 2) James M. Headrick Naval Research Laboratory, retired (CHAPTER 20) Dean D. 
 IRE, vol. 36, pp. 1205-1214, October, 1948. 
 Therefore the peak at the origin is of fixed height  and the function encloses a fixed volume. A reasonable approximation to the ideal ambiguity  diagram might appear as in Fig. 1 1.8. 
 To simplify the transformation process of ArcSAR DEM image, we propose a transformation method in polar coordinate system. The DEM image in polar coordinate system is shown in Figure 8. Theθ-axis of the coordinate system represents the azimuth direction. 
 Since the relative permittivity of  water is in the order of 80, even small amounts of moisture cause a significant increase  of the relative permittivity of the material. A large number of workers have investi - gated the relationships between the physical, chemical, and mechanical properties of  materials and their electrical and, in particular, microwave properties. In general, they  have sought to develop suitable models to link the properties of the material to its elec - tromagnetic parameters. 
 This blockage pattern is subtracted from unperturbed (unblocked) aperture  fields, as shown in Figure 12.6. The associated patterns, with and without blockage, are shown in Figure 12.7. The  alternating large, small, large, and so on, sidelobe progression is characteristic of a  blocked aperture. 
 ........  3  RADAR APPLICATIONS  ................................ ................................ 
 INSTRUMENT PAYLOAD INCLUDES THE 0RECIPITATION 2ADAR  02   WHICH WAS DESIGNED AND  BUILT BY *!8! THEN .!3$!   AND WAS THE FIRST OF ITS KIND ON A SPACE 
 Staudaher, F. M.: Airborne MTI, chap. 18 of" Radar Handbook," M. 
 Lindauer, J. T., and N. K. 
 CONDUCTING MAGNET WITH A CLOSED 
 BIGUOUSLY 4HE DETECTION THRESHOLDS ARE SET TO PROVIDE APPROXIMATELY ONE FALSE ALARM PER MINUTE 4HE EFFECTIVENESS OF -273 IS DEPENDENT ON THE ABILITY TO DETECT TARGETS AT THE REQUIRED  RANGES WHILE SIMULTANEOUSLY REJECTING DISCRETE CLUTTER DETECTIONS ,OW TWO 
  -ULTIMODE 2ADAR 0ROGRAM v IN  )%%% .!%#/.      P    2 .EVIN  h!.!0' 
 J. Capon, “Optimum weighting functions for the detection of sampled signals in noise,” IRE  Trans. Information Theory,  vol. 
 If the waveform of the echo signal were  known, as well as its carrier frequency, the matched filter could be specified as outlined in  Sec. 10.2.  Several factors tend to spread the CW signal energy over a finite frequency band. 
 Each kind of target was clustered well. Therefore, aspect entropy can discriminate between dihedral B and the trihedral despite their scattering mechanisms being similar. Therefore, different targets can be discriminated from each other according to the value of the aspect entropy. 
 Because oftheslow rate ofScan, itisimpera- tive touseasecond radar todetermine theapproximate direction ofthe target. The Type 7equipment was widely used forthis function. The azimuth position oftheType 13radar isshown onthePPI oftheType 7 bymeans ofabeam oflight pr~20°15” 10” 8“jected from behind the phospho-6“ rescent screen ofthe PPI. 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars.  SPACE-BASED REMOTE SENSING RADARS  18.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 conventional interferometric SAR measurements from one spacecraft platform usually  are not practical, since the implied spatial or temporal separations of the measurements  are much larger than one satellite could support. (An alert reader may note the obvious  exception to this rule, SRTM described previously, which mounted its second inter - ferometric antenna on a 60-m extendable strut.) Satellite orbits tend to be well-known, and follow very similar trajectories over  subsequent repeat periods. 
 PERSISTENCE MONOCHROME #24S THROUGH THE APERTURE OF A HOOD ARE LONG GONE -ORE RECENTLY  HIGH BRIGHTNESS COLOR #24S ARE BEING REPLACED BY ,IQUID #RYSTAL $ISPLAY FLAT PANEL TECHNOLOGY  WHICH IS HELPING TO MAKE THE DISPLAY MORE USER ACCESSIBLELARGE STAND 
 Intell. 1980 ,P AMI-2 , 165–168. [ CrossRef ] 24. 
 FREQUENCY POLARIMETRIC SNOW DISCRIMINATION  IN ALPINE AREAS v 0ROC )'!233  VOL 6)  PP n    , , (ESS ET AL  h$ELINEATION OF INUNDATED AREA AND VEGETATION ALONG THE !MAZON FLOODPLAIN  WITH THE 3)2 
 Hansen, V. G., and B. A. 
 In a cylindrical array, the radiation pattern cannot be separated into an  element factor and an array factor as in planar array theory. Each element points in a dilTerenl  direction. Thus computations of patterns must include both element and array together. 
 M. Headrick Naval Research Laboratory 24.1 INTRODUCTION Beyond-the-horizon ranges up to thousands of nautical miles can be achieved by radar operation in the high-frequency (HF) band (3 to 30 MHz). The longer-range performance is achieved by using sky-wave propagation. 
 The helix TWT is capable of bandwidth in excess of an octave (2 to 1), which is  much higher than other radar tubes. The TWT is often thought of as a very broadband  tube, but the broad bandwidth of a helix TWT is not of great significance in radar  applications since the helix TWT is limited in its peak power to a few kW. This means  that the helix TWT is best used in CW or high duty cycle radar applications, if at all. 
 9. Eaves, J. L., and E. 
 The other cliannel is similar, except for a 90" phase delay introduced in the reference signal.  7'lte outpt~t of tlte chan~lel B mixer is  If the target is approaching (positive doppler). the outputs from the two channels are  On the other hand, if the targets are receding (negative doppler),  Tlie sign of (I), and the direction of the target's motion may be determined according to  whether the output of channel B leads or lags the output of channel A. 
 WIDTH IS FIXED  IT CAN BE  SHOWN THAT THE WEATHER 
 25.3. For a 4/3 earth model, the radius of these cov- erage circles, in kilometers, is approximated by16 rR = 130(Vfc~, + Vh~R) (25.9) . FIG. 
 L. Bovino, “Bistatic radar for weapons location ,” U.S. Army Communications Electronics  Command, Fort Monmouth, NJ, 1994. 
 Following the threshold detector, the outputs from  each of the range channels must be properly combined for display on the PPI or A-scope or for  any other appropriate indicating or data-processing device. The CRT display from this type of  MTI radar appears "cleaner" than the display from a normal MTI radar, not only because of  better clutter rejection, but also because the threshold device eliminates many of the unwanted  false alarms due to noise. The frequency-response characteristic of the range-gated MTI might  appear as in Fig. 
 Rajopadhyaya, and S.K. Avery, “Radar reflectivity  calibration using differential propagation phase measurement,” Radio Sci. , vol. 
 BASED PATTERN REFLECTOR ANALYSIS METHODS  ALL OF WHICH ARE ROOTED IN RAY TRACING AND SOME OF WHICH ARE AUGMENTED WITH DIFFRACTION TERMS FOR IMPROVED ACCURACY !LTHOUGH THE SIMPLE '/ METHOD NO DIFFRACTION TERMS  WORKS REASONABLY WELL  IT IS NOT GENERALLY AS ACCURATE AS 0/ (OWEVER  TWO OF THE MORE COMMON ENHANCED METHODS  'EOMETRICAL 4HEORY OF $IFFRACTION '4$  AND 5NIFORM 4HEORY OF $ IFFRACTION 54$     INCLUDE EDGE DIFFRACTION AND ARE MUCH MORE ACCURATE 54$ IS ESSENTIALLY AN ENHANCE 
 E.: A Matched-Filter Pulse-Compression System Using a Nonlinear FM Waveform, IEEE  Trans., vol. AES-6, pp. 73-78, January, 1970. 
 Patent 2,599,944,   June 10, 1952. 68. W. 
 A variation of the equivalence theorem developed by Kell74 applies to small  bistatic angles, in some cases as small as 5 °: the bistatic RCS of a complex target is  equal to the monostatic RCS measured on the bisector of the bistatic angle at a fre - quency lower by a factor of cos ( b /2). Kell’s complex targets are defined as an assembly of discrete scattering centers  (simple centers such as flat plates, reflex centers such as corner reflectors, skewed  reflex centers such as a dihedral with corner ≠ 90°, and stationary phase regions for  creeping waves). When the wavelength is small compared to target dimensions, these  complex target models approximate conventional aircraft, ships, ground vehicles, and  some missiles. 
 290 303. 1958. 468 INTRODUCTION TO RADAR SYSTEMS  34. 
 (/)  'D 10 c::  ~  5  O~ ______ ~ ______ ~ ________ ~ ______ ~  o 5 10 15 20  Backscatter coefficient (00, decibels)  Figure 9-The derivation of wind speed from the corrected back­ scatter coefficient.  Johns Hopkins APL Technical Digesl, Volume 8, Number 2 (/987) . justment to reference the altimeter height measurement  to the center of gravity of the spacecraft, and the atti­ tude/sea-state correction already discussed. 
 LOOP ADAPTIVE -4) MUST  THEREFORE  BE OPERATED FOR A FINITE SET BATCH  OF PULSES TO ENSURE THAT THIS WILL NOT HAPPEN 3UCH BATCH 
 Component tolerances often lead to some - what different nonlinearities in I and Q, which can generate the variety of spurious  doppler components. The ideal input signal is  V A e I jQj td = = +w  (6.31) Each video channel response can be expressed as a power series. For simplicity,  only symmetrical distortion will be considered. 
 None of the reflected energy appears at port 1. The difference in  path length with the diode switches open and closed is D./. The two-way path D./ is chosen to  correspond to the desired increment of digitized phase shift. 
 The front and rear sig- nals are coherently detected against each other, resulting in a spectrum which contains the doppler-shifted target signal at a frequency roughly proportional to closing velocity. A narrowband frequency tracker searches the spectrum, locks onto the target return, and extracts guidance information from it. The use of CW provides the capability of discriminating against clutter on the basis of doppler frequency and thus allows low-altitude operation. 
 l 1.1 the slope  of the pulse in noise may be written as n( t )/ L\ TR, where n(t) is the noise voltage in the vicinity of  the threshold crossing and L\ TR is the error in the time-delay measurement. Equating the two  expressions for the slope gives \''  or L\TR = 1~1 Aft,  [(L\ TR)2]'12 = bTR = -~---- -__ !,:_ __ (A2/n2)112 -(2S/N)112 ( 11.2)  (l l.3)  where A 2/n2 is the video signal-to-noise (power) ratio. The last part of Eq. 
 RAYS AND ULTRAVIOLET RADIATION RAISE $ 
 For active  aperture phased array radars, it is likely that the solid-state transistor amplifier will  be the choice. REFERENCES  1. M. 
 World CON/: OII Bird Huzards ro Aircruii, Cunuda, pp. 359-376. 1969. 
 and tlie mean square value is THE RADAR EQUATION 21  'Tlie quantities in, and l,lz are sometimes called the first and second moments of the random  variable .u. If .u represents an electric voltage or current, inl is the d-c component. It is the value  read by a direct-curretlt voltmeter or ammeter. 
 !PERTURE *AMMING  4HE BASIC NOTION BEHIND -&!2 HIGH POWER 
 The ground area is proportional to ∆r, and  the projected area is smaller. Thus, or σ γ γ θ σ γ θ0 0A d dA = = =( cos cosprojected area)  (16.3) Since both g  and s 0 are called scattering coefficients, readers of the literature must be  especially careful to determine which is being used by a particular author . Radar astronomers use a different s3:  total returnpowerfrom entire surface powerreturn nedfrom perfectisotropicsphereofsameradius (16.4) The resulting value for s  is usually much smaller than s 0 for the planet at vertical  incidence and is larger than the values of s 0 near grazing incidence (return from the  limb of the planet). 
 Dynamotors have been built i FIG.14.23 .—Eicor Inc. aircraft dynamotor, togive voltages ashigh as2000 volts, but such machines meet severe difficulties with commutation and insulation. Dual- and triple-output dynamotors arevery common, and several machines having four outputs (Fig. 
 RELATED VARIABLE #RYO3AT 4HIS WAS THE FIRST %ARTH %XPLORER /PPORTUNITY -ISSIONS  WHICH WAS PART  OF THE %UROPEAN 3PACE !GENCYS ,IVING 0LANET 0ROGRAMME 4HE MISSION CONCEPT   WAS SELECTED IN  AND SUBSEQUENTLY LAUNCHED IN /CTOBER  5NFORTUNATELY  THE LAUNCH VEHICLE MALFUNCTIONED %3! AND ITS MEMBER STATES AUTHORIZED A REPLACEMENT 4HE #RYO3AT ORBIT HAS A HIGH 
 DOPPLER COVERAGE OF  KMn K(Z IS SHOWN IN &IGURE   4HIS SET IS FOR A  n ANTENNA BEAMWIDTH  OWNSHIP IE  THE RADAR CARRYING FIGHTER   VELOCITY OF  MS  AND AN ANGLE OFF THE VELOCITY VECTOR OF  n 4HE 02& SET IS                AND  K(Z (ISTORICALLY  A 02& SET WAS CALCULATED DURING DESIGN AND REMAINED FIXED DURING DEPLOYMENT  -ODERN MULTIFUNC 
 Trafﬁc loading also has much more inﬂuence on land subsidence because it can cause foundation deformation. Region 2 (Figure 9) is a new central business district (CBD) of the city where many high-rise buildings concentrated in, such as Wuhan Center Tower (438 m). Many new buildings and transport facilities have been constructed or being constructed. 
 Methods for dealing with the cross sections of  complicated targets are discussed in the next section.  2.8 CROSS-SECTION FLUCTUATIONS  The discussion of the minimum signal-to-noise ratio in Sec. 2.6 assumed that the echo signal  received from a particular target did not vary with time. 
 LIMITED CONDITIONS EG  CONTINUOUS 
 1, vol. 18, pp. 104-109, November, 1945; pt. 
           
 133. S. Strappaveccia, “Spatial jammer suppression by means of an automatic frequency selection  device,” IEE Int. 
 An additional advantage of these long wavelength  radars is their ability to measure not only the radial vertical wind components directly,  but also the mean horizontal wind that is transverse to the vertical beam without  scanning that beam off zenith. These profilers use the so-called spaced antenna tech - niques with multiple receivers to process the amplitude and phase differences of  the echo structures as they translate over two adjacent antennas (usually subarrays  of the same array antenna) to measure components of the horizontal or transverse  wind.190 In this manner, two orthogonal subarrays can measure components of the  horizontal wind using cross-spectral or correlation processing techniques.191 Since  the measurement is made in pairs of overlapping beams directly above the radar, it is  no longer necessary to assume or require horizontal homogeneity of the wind field in  the larger area above the radar and/or the long integration times necessary to assure  this homogeneity. These spaced antenna techniques are most frequently used when  high spatial and temporal resolution measurements are required such as estimating  detailed boundary layer turbulence fields. 
 Signal Processing. The analog output of the receiver is downconverted to baseband (dc) via quadrature mixing. The in-phase and quadrature signals are passed through a matched filter and converted to digital words by an analog-to- digital (A/D) converter. 
 At any  particular antenna position a radar normally observes many range resolution intervals, per­ haps several hundred. At each range interval within ~he beamwidth of the antenna a decision  has to be made concerning the presence or absence of a target before the antenna beam can be  positioned to a new direction. Therefore the dwell time in any direction is determined not by  the average number of observations made by each sequential detector, but by that range  interval which requires the largest number of observations. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.86  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 by using radar returns in adjacent cells in range and azimuth. Through the use of such  spreading, an additional degree of control over the clutter map velocity response can  be achieved. 
 S. D. Robertson, “Targets for microwave navigation,” Bell Syst. 
 ● Because of saturation effects, amplitude errors in cascaded stages do not simply add.  However, amplitude errors in driving stages will cause drive-induced phase varia - tions in the following stages, as noted above, all of which must be counted. ● Time jitter in cascaded stages simply adds unless the stages are arranged to cancel or  to be root-sum-squared. 
 Figure12.7isaplotoftheelectricfieldstrength (relative tofreespace)atthetargetasa function ofthedistance fromthetransmitting antenna. Boththeradarantenna andthetarget arcassumcd tohcatafixedheight(100IIIinthisexample). Thecomputed curvesapplyto propagation ovcranidealized smoothcarthintheabsenceofanatmosphcre. 
 STATE TRACKING GAINS 4HE TRADEOFFS FOR EMPLOYING A +ALMAN FILTER FOR RADAR TRACKING GENERALLY ARE TUNING  THE FILTER FOR THE DESIRED DEGREE OF FILTERING  SELECTING THE TRACKING COORDINATES  AND  ADAPTING THE FILTER TO DEAL WITH CHANGES IN THE TARGET MOTION EG  MANEUVERS  DIFFERENT PHASES OF BALLISTIC FLIGHT  AND SO ON  4UNING THE +ALMAN &ILTER  4HE GREATEST ADVANTAGE OF THE +ALMAN FILTER FOR RADAR  TRACKING IS THAT IT PROVIDES A SYSTEMATIC WAY OF CALCULATING GAINS (OWEVER  A DISADVAN 
 59. A. E. 
 Yang, Z; Yanfang, L.; Yi, L. Spatial and Temporal Patterns Analysis of Impervious Surface in Wuhan City. Sci. 
 This is discussed more fully in Sec. 7.7. Shaped Beams. 
 33, pp. 83--96. April, 1956. 
 Soc. Ser. B 1996 ,58, 267–288. 
 417–423, July 1984. 193. L. 
 PRESSION RATIO ARE EQUAL TO THE NUMBER OF SUBPULSES IN THE WAVEFORM IE  THE NUMBER OF ELEMENTS IN THE CODE /PTIMAL "INARY #ODES  /PTIMAL BINARY CODES ARE BINARY SEQUENCES WHOSE PEAK  SIDELOBE OF THE APERIODIC AUTOCORRELATION FUNCTION IS THE MINIMUM POSSIBLE FOR A GIVEN CODE LENGTH #ODES WHOSE AUTOCORRELATION FUNCTION  OR ZERO 
 ING MECHANISMS   4HE SIGNAL PROCESSING STAGE MAY ALSO BE TASKED WITH EXTRACTING  ENVIRONMENTAL INFORMATION FROM THE RADAR ECHOES  AS MENTIONED IN 3ECTION  4HIS INCLUDES REMOTE SENSING OF OCEAN WINDS AND SEA STATE  LAND 
 Geopkys. Rtps..  vol. 
 Only the part that passes the low-pass  filters in a detector is shown in the figure. The rectangular RF spectrum  has become  a triangular video spectrum . This spectrum describes the fading of the detector output for a CW radar. 
 The advantage of long life claimed for solid-state transmitters seems matched  by the long life obtained with linear beam tube transmitters.  The transistor amplifier, and the bulk-effect and avalanche diodes have important appli-  cations in radar; but in the form in which they have been known, it is not likely that they will  cause the high-power microwave tubes to disappear in the way their lower frequency counter-  parts have displaced the receiver vacuum tube.  REFERENCES  I. 
 COMPONENT WAVELENGTH IS  , 7HEN THE SIGNAL TRAVELS AN EXTRA DISTANCE  K   $2  BETWEEN THE SOURCE AND TWO SUCCESSIVE WAVE CRESTS  THE PHASE DIFFERENCE BETWEEN THE ECHOES FROM SUCCESSIVE CRESTS IS  SO THE ECHO SIGNALS ALL ADD IN PHASE )F THIS CONDITION IS SATISFIED FOR A PARTICULAR  , AND P  IT FAILS TO BE SATISFIED FOR OTHERS  4HUS  THIS IS A RESONANT SELECTION FOR A GIVEN  P  OF A PARTICULAR COMPONENT OF THE  SURFACE , 4HE STRENGTH OF THE RECEIVED SIGNAL IS PROPORTIONAL TO THE HEIGHT OF THIS  COMPONENT AND TO THE NUMBER OF CRESTS ILLUMINATED BY THE RADAR )F THE SURFACE HAS AN UNDERLYING CURVATURE  THE NUMBER OF ILLUMINATED CRESTS SATISFYING THE RESONANCE CRITERION MAY BE LIMITED BY THE LENGTH OF THE ESSENTIALLY FLAT REGION OTHERWISE  IT IS LIMITED BY THE RADAR RESOLUTION 4HE THEORETICAL EXPRESSION FOR THE SCATTERING COEFFICIENT IS   SS Q A QPQ PQ     K7 K C O S \ \  S I N     WHERE P  Q   POLARIZATION INDICES ( OR 6      K   OK THE RADAR WAVENUMBER   @((   2 &RESNEL REFLECTION COEFFICIENT FOR HORIZONTAL POLARIZATION   AEQE Q EQ E66 
 H.: Passive Remote Sensing at Microwave Wavelengths, Proc. IEEE, vol. 57, pp. 
 R.: Microwave Plastna Beam Sweeping Array, IRE Trans, vol. AP-10, pp. 96-97, January,  1962. 
 F. Shaeffer, and M. T. 
 The principal factors that affect the range resolution of a radar are the length of the transmitted pulse, receiver gain, CRT spot size, and the rangescale. A high degree of range resolution requires a short pulse, low receivergain, and a short range scale. Pulse Length Two targets on the same bearing, close together, cannot be seen as two distinct pips on the PPI unless they are separated by a distance greater thanone-half the pulse length (164 yards per microsecond of pulse length). 
 DOPPLER WINDOW IS TOO SMALL TO  BE USEFUL .ARROWING THE EFFECTIVE ANTENNA PAT 
 Appl. Math., vol. 3, pp. 
 If the phase y  is constant with frequency, the scan  angle q0 is frequency-dependent. Time-Delay Scanning.  Phase scanning was seen to be frequency-sensitive; how - ever, time-delay scanning is independent of frequency. 
 Plumbing loss. There is always some finite loss experienced in the transmission lines which  co~~rlect tlle oirtpi~t of tile tratist~litter to the antenna. The losses in decibels per 100 ft for radar  transmissio~~ lines are sllowri ill Fig. 
 WATT TRAVELING WAVE TUBE  AMPLIFIER 2ATHER THAN PULSE OR CHIRP MODULATION   6ENERA USED A CONTINUOUS TRANSMISSION  MODULATED BY A CODED SEQUENCE OF  n PHASE SHIFTS 4HE RECEIVED SIGNAL WAS DIGITIZED  INTO  COMPLEX NUMBERS  BITS )   BITS 1  ! RADAR LOOK WAS TAKEN EVERY  SECONDS AND STORED IN A 2!- MEMORY BUFFER 4O KEEP UP WITH THIS DATA RATE  RECORDING ALTERNATED BETWEEN TWO ONBOARD TAPE RECORDERS $ATA WERE DOWNLINKED EACH ORBIT  ^ -"YTES   AND THEN PROCESSED IN GROUND 
 For  convenience, tb.e entire structure is shown enclosed within a radome. Fixed feeds illuminate  each reflector. A single radar transmitter and receiver is switched among the four sets of feeds  on a time-shared basis every 90" rotation of the mirror. 
 l>--··0-----~~ >--~-Phase  ,hif fer  Figure 8.23 Reflectarray.  may be placed ofT-axis lo avoid reflections from the back face of the lens, if desired. It is  possible in a lens array lo reduce the number of phase shifters by "thinning" the number or  output radiators. 
 TRACK ASSOCIATION IS CLEARLY BET 
 Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 5.46  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 85. D. 
 The above methods of target classification depend on extracting some-  thing about the target other than its location. However, the target track, which is obtained  from location data alone, can provide significant information that can be used in the  identification process, especially in a military situation. The speed, course, and maneuver of a  target can indicate something about its intent; and therefore a form of target classification is  possible. 
 Foreachtargetthe necessary information tobepresented mightconsistofperhaps tenalphanumeric characters andanumber oflinesegments.J5Whentheamount ofdataislarge,writingtimemight havetobetakenfromtheradartimebyblanking oneoutofeverynsweepsorwritingthe synthetic information duringarandom interruption ofthesweep.Itisalsopossible toutilize asecondelectron gunintheCRTtominimize theamount oftimetakenfromtheradarto insertthesynthetic data.Another methodforachieving thenecessary timetodisplayalpha­ numeric dataistostorethevideoinashiftregisterandthenreaditoutatahigherrate. TheCCD,orchargecoupled device,isonepossibility asashiftregister. Thedataonthesynthetic displaymustberefreshed atasufficiently highratetoobtain ahighbrightness andtoavoidl1icker.Whenanumberofdisplays areusedwiththeoutput ofasingleradar,adedicated minicomputer canbeusedateachdisplayposition forthe refreshofdatasoastoreducethedata-transfer ratefromtheradarcentralprocessor. 
 is the beat frequency due only  to the target's range. If the rate of change of the carrier frequency is Jo, the beat frequency is  . 2R . 
 PULSE DOPPLER RADAR  4.376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 targets, Alert/Confirm provides the range measurement of classic HRWS waveforms  without the frame time expense of transmitting linear FM ranging dwells every beam  position. The Confirm dwell can also be used to control false alarms, permitting the  Alert dwell to be more sensitive than classic VS. The Alert phase is used to search each beam position of the frame for the presence  of a target. 
 One obtains the baseband around the zero frequency directly by mixing the osci l- lator and receiving signal. The lower frequency limit is critical with this method, since it d e- termines the smallest meas urable velocity.  Additionally, the baseband is influenced by the  FM noise of the oscillator and by the sensitivity to spot & flicker noise. 
 The  data processing is usually so applied that a certain number of point targets in the distance (> 32) and the stored angles (history) are tracked and are evaluated in their significance for th e  same lane as the traveling automobile.  For range determination almost all well -known proce- dures are employed, such as Pulse Radar, FM -CW, Pseudo Noise and Multifrequency CW  procedures, whereby the FM -CW is the most frequently used procedure.  The antenn as are  usually quasi -optically formed and the individual directivities are switched electronically. 
 Barrick, “Extraction of wave parameters from measured hf radar sea-echo spectra,” Radio  Science, vol, 12, no. 3, p. 415, 1977. 
 Fortunately, a close relation - ship between radar and oceanography has grown up in the fields of remote sensing,  leading to the accumulation of a large amount of information, both experimental  and theoretical, about how scattering at radar frequencies relates to oceanographic  variables. In many ways, this information serves as the basis of much of our current  understanding of sea clutter. In modeling sea clutter, there is a difference between a theory,  which relates the  physical scattering properties of the sea surface to the received signal, and a charac - terization,  which provides a description of the sea clutter data in terms of a statistical  model (e.g., Rayleigh, lognormal, Weibull, and K-distribution) that, although some - times suggestive of physical processes in the underlying scattering, is of greater direct  interest to the radar system designer in providing detection probabilities and false  alarm rates. 
 d: 2  ha($) = ( A(z) exp  ' -dl2  Suhstituririg Eq. (7.14) irito tlie above and changing the variable of integration from b, to 5' to  avoid corifi~siori. ti\c :triteriria patter11 hecornes  Intcrclinrigirig tlie order of integration, the approximate antenna pattern is ~~(4) = I id" la E(i) exp (sin d, - sin <) .I. 
 OF 
 PAIR PROCESSOR WAS THE TECHNIQUE OF  CHOICE (OWEVER  IN MANY RESEARCH APPLICATIONS  IT REMAINS ADVANTAGEOUS FOR IMPROVED DATA QUALITY CONTROL PURPOSES TO ACCESS THE FULL DOPPLER SPECTRUM AND REMOVE ARTIFACTS PRIOR TO COMPUTING THE SPECTRAL MOMENTS CORRESPONDING TO THE METEOROLOGICAL DATA OF INTEREST   4HE WIND PROFILING RADAR COMMUNITY HAS MADE EXTENSIVE USE OF SPEC 
 Kraus. J. D.: "Antennas." McGraw-Hill Book Co.. 
 These can be undesirable in some military applications since they might  provide a distinctive feature for recognizing a particular radar.  An example of a traveling-wave tube designed for radar applications is the S-hand Varian  VA-125A. It is a broadband, liquid-cooled TWT which uses a clover leaf coupled-cavity  slow-wave structure. 
 LUTION CELL IS   MS  N    PULSES ARE NONCOHERENTLY  INTEGRATED  THE FILTERING CONSTANT  IS  @      THE UPDATE INTERVAL IS  S  AND THE  3.2    D" /N EACH SCAN  THE CLUTTER  MAP CELL IS UPDATED WITH THE RADAR AMPLITUDES IN THE FIVE RANGE CELLS FALLING WITHIN THE CLUTTER MAP CELL AND WITH THE AMPLITUDE FROM ONE ADDITIONAL RADAR RESOLUTION CELL BEFORE AND AFTER THE CLUTTER MAP CELL&)'52%  5NIVERSAL CURVE FOR DETERMINING DETECTABILITY LOSS CAUSED BY THE  CLUTTER MAP &)'52%   4RANSIENT RESPONSE OF CLUTTER MAP DUE TO  3WERLING #ASE  POINT CLUTTER MODEL .   -4) 2!$!2  Ó°nÇ )T IS SEEN FROM &IGURE  THAT THE VELOCITY RESPONSE CHARACTERISTIC OF THE CLUTTER  MAP FROM STOPBAND TO PASSBAND IS SOMEWHAT GRADUAL IN THIS PARTICULAR IMPLEMENTATION  4HIS IS PARTLY DUE TO THE LARGE SIZE OF THE CLUTTER MAP CELL RELATIVE TO THE RADAR RESOLU 
 Even these can be quite difficult to locate in  adverse sea clutter conditions. The first dash displayed on the radar screen could be up to 0.8 nm away from the  actual SART position and so search craft have to take precautions not to run down  the survival craft when bearing down on the signal. At short ranges, the swept gain  of the radar may truncate the nearer dashes. 
 IN METAL SPHERE THAT PROVIDES A POINT SOURCE TARGET TO ELIMINATE TARGET 
 HORN FEED HAS BEEN USED AS ILLUSTRATED IN &IGURE  4HE FIVE 
 DELAY CANCELER WITH BINOMIAL WEIGHTS IN AN UNSTAGGERED SYSTEM WILL PERFECTLY  CANCEL 6T    C   AT  4HE CHOICE OF  !    IN BOTH CASES IS ARBITRARY )N THE THREE 
 BASED PRECEDENT  RESULTED FROM USE OF THE SAME 2& HARDWARE AS  THE 3!2 MODE !S A CONSEQUENCE   SIMULTANEOUS 3!2  AND SCATTEROMETER OPERATIONS WERE NOT POSSIBLE )N CONTRAST TO  + U BAND  THE # BAND DATA  WERE LESS DEGRADED BY RAIN AND PROVED TO BE MORE RELIABLE FOR HIGHER WIND SPEEDS  4HE ANTENNA SWATHS SPANNED  KM  FROM WHICH THE AVERAGED DATA FROM THE THREE 
 TRACKING PROBLEM THROUGH THE SELECTION OF THE COVARIANCE MATRIX   1T K   OF THE  UNKNOWN RANDOM MANEUVER 4HE GOAL OF THIS SELECTION IS TO OBTAIN THE BEST POSSIBLE TRACKING PERFORMANCE FOR THE MORE COMPLEX CASES OF INTEREST WHILE STILL USING THE SIM 
 The disturbance noise extends over the entire swath of the SAR  image, and it shows generally a uniform intensity. The radar image of barrage jam - mer noise will exhibit speckle, i.e., a brightness variation from one resolution cell to  another. In addition, because a large number of noise samples are added noncoher - ently, the multiple looks of jammer noise tend to smooth out the intensity variation  from pixel to pixel, just as in the case of thermal noise. 
 POLE  FILTER  ARE DETECTORS THAT MINIMIZE THE DATA STORAGE REQUIREMENTS 7HILE THESE DETEC 
 1–6. 6. Meyer, F.; Bamler, R.; Jakowski, N.; Fritz, T. 
 Iftheseparation between the individual scattering objectsislargecompared withthewavelength-and thisisusuallytrue formostradarapplications-the phasesoftheindividual signalsattheradarreceiverwillvary astheviewing aspectischanged andcauseascintillating echo. Consider thescattering fromarelatively" simple" complex targetconsisting oftwoequal. isotropic objects(suchasspheres) separated adistanceI(Fig.2.14).Byisotropic scattering is meantthattheradarcrosssectionofeachobjectisindependent oftheviewing aspect.The separation Iisassumed tobelessthancr/2,wherecisthevelocity ofpropagation andristhe pulseduration. 
 1972.  17. Gardner, F. 
 Atlas et al. went even further by comparing  the measured and theoretical RCS of Plexiglas spheres in their attempts to understand  the scattering by hailstones.6 The RCS of very slender dielectric bodies does not exhibit this complexity, how - ever, because the sources of reflection (front and back sides of a dielectric cylinder, for  example) are too close to each other to be resolvable by the incident wave. An example  is the broadside RCS of a thin string shown in Figure 14.4. 
 Fujita and Caracena139 first identified the microburst phenomenon  as the cause of an airliner crash that took place in 1975. The microburst and its effects  on an aircraft during takeoff or landing are depicted in Figure 19.7. The microburst is  simply a small-scale, short-duration downdraft emanating from a convective storm. 
 ING PULSE COMPRESSION WAVEFORMS ARE DISCUSSED IN THE SECTION ON PULSE COMPRESSION IMPLEMENTATION IN THIS CHAPTER $ISCUSSIONS HERE WILL CONCENTRATE ON THE WAVEFORM ITSELF 4HE PRIMARY FACTORS INFLUENCING THE SELECTION OF A PART ICULAR WAVEFORM ARE USU 
 13, no. I, pp. 10-11, Jan. 
 32  . Superrefracting ground ducts may also be produced by the diverging downdraft under a  thunderstorm.31 The relatively cool air which spreads out from the base of a thunderstorm  results in a temperature inversion in the lowest few thousand feet. The moisture gradient is  also appropriate for the formation of a duct. 
 Roycil Radar Esrtrhlisl~t~~c~~~t  Atcv~torcrtrdrr~r~ no. 2557. July. 
 The actual enhancement is usually less  than this, primarily because of the directivity of the antennas and imperfections in the  ground plane. Antenna directivity precludes the target ever being squarely aligned on  the boresights of both the real antenna and its image in the ground plane at the same  time, and the reflection coefficient of typical ground planes varies from 95% to as low  as 50% or less. For all except very high and very low frequencies (millimeter wave - lengths and VHF), typical sensitivities are of the order of 7 to 10 dB above free space  instead of the ideal 12 dB. 
 Gcncrally it can hc  said t1i:it tllc ar~~~,litirtlc-cor111,ar is011 nio~iopulsc trackirig system is ~isually preferred over tliis  Iiyhrid techriiquc  I'haw-con~parisotr nio~ropt~lse. Tlie tracking teciiniques disc:i~ssed thus far in this chapter were  i,;~s~tl on it corlljvtr is011 01 tlic III)IIIII'III(ICS of eclio signals received from two or Inore antenna  positionr. .l'lie sequerltial-lobing arid conical-scan techniques used a single, time-shared  itritcriri:i I~ciit~l. 
 NOISE AMPLIFIER --)# 3HOWN  HERE ARE THE SPIRAL INDUCTORS  METAL 
 Cook, “Status of ground-probing radar and some recent experience,” in Proc. Conf.  Subsurface Exploration for Underground Excavation and Heavy Construction , Amer. 
 OUSLY DEGRADED THAN IF THE FAILURE WERE TO OCCUR IN A RECEIVER CONNECTED TO AN ELEMENT AT THE END OF THE ARRAY !UTOMATIC DETECTION OF SUCH A FAILURE AND REALLOCATION OF AN END ELEMENT RECEIVER TO THE MIDDLE ELEMENT OF THE ARRAY WOULD MINIMIZE THE DEGRADATION Óä°£ÎÊ , ,Ê* 
  # 
 PHASE OVER GAIN STATES 4HEREFORE  IT IS DESIRABLE TO CALIBRATE THE ATTENUATOR FIRST 4HE PHASE SHIFTER CAN THEN BE CALIBRATED WITH 
 The elements ofasystem for transmitting this information are indicated inFig. 17.1. The radar data are delivered from the settoa “synchronizer” which. 
 The CFA can be pulse-modulated by turning on and off the high voltage between the  anode (at ground potential) and the cathode (at a large negative potential). This is called  cathode pulsing. The RF drive is usually applied to the CFA before the high voltage is applied  since an RF signal is needed to start the emission process in a secondary-emission cathode. 
 Aseach type ofcontrast isdiscussed, itwill beillustrated byradar scope photographs. 3.12. Specular and Diffuse Reflection.-0f theseveral ways inwhich airborne radar gives itsinformation, the most important isthrough the contrast between rough and smooth surfaces. 
 4.13 to 4.14. 50. M. 
 Figure 18. Imaging test for closed chamber. ( a) Imaging system and target scene; ( b) distribution of targets. 
 CORRELATION SIDELOBES IS VITAL TO ACHIEVE GOOD RANGE RESOLUTION AND THE SIDELOBES ARE AFFECTED BY THE ANTENNA AND SYSTEM CHARACTERISTICS AS WELL AS THE DURATION AND RANDOMNESS OF THE TRANSMITTED WAVEFORM &URTHER INFORMATION IS GIVEN BY .ARAYANAN  AND 3ACHS ET AL  Ó£°ÇÊ  / 
 LEVEL RISE TO AN ACCURACY OF  MILLIMETER PER YEAR )N ADDITION TO SEA 
 , vol. 50, pp. 170–175, 1966. 
 A beacon on a cooperative target can provide a point source (single-pulse response)  to eliminate range error caused by the target. However, very stable circuitry is required  to avoid pulse jitter and drift. Doppler Scintillation and Spectral Lines. 
 Mitnik, L.M.; Dubina, V .A.; Shevchenko, G.V . Ers sar and envisat asar observations of oceanic dynamic phenomena in the southwestern okhotsk sea. In Proceedings of the 004 Envisat & ERS Symposium, Salzburg, Austria, 6–10 September 2004. 
 Even though aneffort hasbeen made toreduce ther-fpulse amplitude, this trouble may persist inasubtle form. Iftheattenuator preceding thelocking mixer isofthesimple ‘‘waveguide-beyond-cutoff” variety, itmay allow harmonic frequencies, generated bythetransmitter, 1S.Roberts, “AMethod ofRating theStability ofOscillators forMTI,” RL Report No.819, Oct. 16,1945.. 
 NOISE RATIO THAT IS OF INTEREST !CCORDINGLY  A DIFFERENT FORM OF THE RADAR EQUATION MUST THEN BE EMPLOYED  0ROPAGATION  FACTORS  & P  3EVERAL PROPAGATION PHENOMENA  INCLUDING &ARADAY  POLARIZATION ROTATION  GROUND 
 46 BAND FROM  TO  -(Z WITH AN  -(Z BANDWIDTH THE SPECTRAL WIDTH OF A 46 CHANNEL    K7 PEAK POWER AT  EFFICIENCY  AND AN AVERAGE POWER OF  K7 OR GREATER 4HE SINGLE INPUT CAVITY CAN BE MADE TO TUNE OVER THE ENTIRE BAND WITH LOW 6372 4HUS  THE CONSTANT EFFICIENCY AMPLIFIER IS A GRID 
 21. Fenster. W.: The Application. 
 LEVEL STAGES OF SIGNAL AMPLIFICATION CAN GENERALLY BE DESIGNED TO ADD ESSENTIALLY ZERO NOISE  BUT MECHANICAL VIBRATION IN THE HIGH 
 9.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 T racking Radar Dean D. 
 66. McCaskill, T. B., J. 
 AES-7,  pp. 147–159, May 1971. 43. 
 Nat. Hazards 2016 ,84, 271–291. [ CrossRef ] 52. 
 TION BEAM 
 WALK   $FD GENERATED BY A MOVING TARGET 3PECIFICALLY   $FD   TO 
 FIG. 14.4 Marsh and Wiltshire microwave bridge. At resonance the cavity is nearly a perfect absorber, and the residual reflec- tion is tuned out with the variable short and variable attenuator. 
 Therefore, αwas set to be −0.001486 according to Equation (11). Γ0/υwas set to be 10 π, adjusting the simulated eddy spirals to ﬁt well with the actual eddy shape. The radar parameters were set with reference to the ENVISAT-1 ASAR parameters listed in Table 3. 
 STATE  AMPLIFIER USING A &%4 AS THE SEMICONDUCTOR DEVICE IS GIVEN BY THE RELATIONSHIP   02&-!8   )-!8   6$'"  
 92-99, April 1952. 3. Dickey, F. 
 Repeaters usually require some form of memory for microwave signals to allow anticipatory returns to be generated; this is usually implemented by using a microwave acoustic memory or a digital RF memory (DRFM).12 The most common type of deception jammer is the range-gate stealer, whose function is to pull the radar tracking gate from the target position through the in- troduction of a false target into the radar's range-tracking circuits. A repeater jammer sends back an amplified version of the signal received from the radar. The deception jammer signal, being stronger than the radar's return signal, cap- . 
 1974.  99. Tolbert, C. 
 SCATTERED RADIOWAVE DIRECTED TOWARD THE RECEIVER /F COURSE  THERE ARE  IN PRINCIPLE  INFINITELY MANY PAIRS OF WAVE TRAINS THAT CAN SATISFY THIS CONDITION  HENCE  THE INTEGRAL !ND THERE IS ANOTHER COMPLICATION 4HE INDIVIDUAL OCEAN WAVE TRAINS ARE NOT COMPLETELY INDEPENDENTTHEY INTERACT WEAKLY AND PRODUCE EVANESCENT NONLINEAR PRODUCT WAVES THAT  WHILE NOT FREELY PROPAGATING  CHANGE THE GEOMETRY OF THE SEA SURFACE AND CONTRIBUTE TO THE SCATTERED FIELD AT SECOND ORDER  ALSO VIA "RAGG SCATTERING 4HUS  AS SHOWN FIRST BY "ARRICK   THE SECOND 
 4.Small ultraportable mobile sets. Inselecting aspecific engine-generator set, orany specific alternator, serious consideration must begiven tothe specifications ofthe set(the alternator inparticular) ifsatisfactory performance and characteristics aretobeobtained. One good tabulation ofstandard Army power sup- plies isSignal “Corps Manual TM 11-223. 
 4(% 
    B. 
 Ê  Ê "** 
 Itsorigin ismade clear byanexample, Fig. 9.36, which represents aship heading north toward the reader, listing tostarboard. The circle represents alarge. 
 T ectonophysics 2012 ,514, 1–13. [ CrossRef ] 23. Li, S.S.; Li, Z.W.; Hu, J.; Sun, Q.; Yu, X.Y. 
 The STC onset  range represents the range at which a large discrete target in the sidelobes exceeds the  CFAR threshold. ch04.indd   22 12/20/07   4:52:43 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 55. D. O. 
 CALLY A VERY SHEER FABRIC 
 Instead. it is believed that the observed backscattering can be explained as reflections  from atmospheric turbulence associated with inhomogeneities in the refractive index These  inhomogeneities might be caused by differences in the water vapor. temperature, and pressure. 
 TO 
 77.4 RANGE-AMBIGUITYRESOLUTION Several methods of ranging are commonly employed in high PRF, while medium PRF is usually confined to multiple discrete PRF ranging. High-PRF Ranging. Range-ambiguity resolution in high PRF is performed by modulating the transmitted signal and observing the phase shift of the modulation on the return echo. 
 For the airborne WAS radar, the antenna usually works in a scanning mode, where the antenna illuminates the surveillance region continuously by steering the antenna beam from one azimuth viewing angle to another. Therefore, the echoes reﬂected from the scatterers on the ground may be coherent in the space. The space coherence property means that more spatial information about the echoes may be mined if proper means are used. 
 By employing some or all of the above techniques, the effect of the sidelobe noise jam mer  can be significantly reduced. Some of the above techniques can also reduce the jamming that  enters via the main beam. The effects of main-beam jamming can be further reduced by  employing a narrow beamwidth to limit the region over which the jamming appears. 
 Inotherexperiments withthePPI,theintegration improvement hasbeenreported tobe proportional to1.5dBperdoubling ofthenumberofpulses,whichcorresponds ton1/2•SO Improvements ashighas1.8dBperdoubling werealsoobserved, butthisislessthanthe2.2to. Number of pulses integrated  Figure 10.6 Improvement of operator detection threshold (signal-to-noise ratio per pulse) as a function of  the number of pulses (sweeps) for side-by-side displays. Curve A, chemical recorder; curve B, cathode-ray-  tube B-scope display; curve C, line of slope 1.5 dB/doubling (m nil2); curve D, line of slope 3 dB/doubling  (cc n) lor perfect predetection integration. 
 TEST SUBPROGRAM IS INVOKED BY THE OPERATIONAL FLIGHT PROGRAM /&0  EXECUTIVE ! SEQUENCE OF SUBROUTINES IS EXECUTED THAT MEASURES PHASE AND GAIN UNBALANCE BETWEEN CHANNELS USING A SIGNAL INJECTED ON THE ANTENNA 4HIS IS USUALLY DONE OVER A RANGE OF INPUT AMPLITUDES  FREQUEN 
 The success of  SeaWinds (discussed later in this section) suggests that the conical scan paradigm will  be the basis for future vector wind scatterometer design. That said, there are two space-based alternatives for measuring vector winds by  microwave means, active and passive. Radars often are unpopular on spacecraft that  host other instruments, of which some may be compromised by radio frequency inter - ference (RFI) generated by a nearby microwave transmitter. 
 COMPRESSION -4) SYSTEM CAN BE 3YSTEMS HAVE BEEN BUILT IN WHICH TRANSMITTER NOISE AND LONG UNCOMPRESSED PULSES COMBINED TO MAKE THE SYSTEMS INCAPABLE OF DETECTING AIRCRAFT TARGETS IN OR NEAR LAND CLUTTER 3OME EXISTING PULSE 
 Ruze, J.: Antenna Tolerance Theory-A Review, Proc. IEEE, vol. 54, pp. 
 Conversely, a  narrow PW supports less  range, but better resolution . This  relationship constitutes one of the  fundamental trade -offs in radar engineering. Pulse  compression with a modulated carrier is often  used to  enhance resolution while maintaining a narrow PW allowing  for higher power  and longer  range . 
 Ltd., London. 1968.  34. 
 Wheeler, H. A.: A Survey of the Simulator Technique for Designing a Radiating Element in a  Phased-Array Antenna,·· Phased Array Antennas, Proceedings of the 1970 Phased Array Antenna  Symposium," Artech House, Inc., Dedham, Massachusetts, 1972, pp. 132 148. 
 Skinner, of Bristol,  ‘inspired their co-workers by their insistence upon the  urgent need for centimetric wavelengths, and by their  own experimental skill. A tremendous drive followed,  until in July 1940 Professor J. T. 
 []M I N  ;     =QQ S          4HE PREVIOUSLY DESCRIBED PROCEDURE CAN THEN BE USED  WITH  DJ BEING DEFINED BY   %Q  INSTEAD OF %Q  , 
 (Thisistheopposite ofNo.2.) 4.Fromradartotargetviareflection fromthesurfaceandreturnbythesamepath (AMB-BMA). Path1istheshortest, path4isthelongestandpaths2and3areequal.Thus,therecanbethree separate responses fromatarget,asillustrated intheidealized sketchofFig.14.11.The relativeamplitudes ofthethreeechoesareintheratioof1,2pandp2,wherep=surface reflection coefficient. Ameasurement oftiletimedelaytDalongwiththerangeRtothetarget andknowledge oftheheighthaoftheradarantenna yieldstheheightofthetarget.This technique worksbestoversurfaces withlargereflection coefficient, andwhenthepulsewidths 2p 1--10 "I~p2 10---~Figure14.11Idealized echoresponse ofapointtarget locatedaboveareflecting surface, forthecasewhere thepulsewidthislessthanthetimeseparation tvbe­ tweenthedirectandsurface-reflected signals.Thesur­ facereflection coefficient isp.. 
 9, 1977. RECEIVERS, OISPLA YS, AND DUPLEXERS 367  24. Watson, H. 
 -Ê",Ê- // 
 BASED .,&- WAVEFORM REDUCES TO AN ,&- WAVE 
 The,%rvomechanism. -Scanner position can berepeated atadistance with anangular error assmall asdesired bymeans ofaservomechanism. >Antenna uCompassRepeater shaft l!mq y~ -~output Amplifier TransmitterRepeater I Differential mqGears---Motor ACllne- FIG,139.-Servo system including compass-dri~-en differential, This term refers toadevice that isarranged toreduce tozero an“error signal” present ~vhen misalignment between transmitter and repeater exists. 
 14.3), or by changing the prf each time the  antenna scans half-a-beamwidth (as in the MTD of Sec. 4.7), or by changing the prf every scan  period (rotation of the antenna).  4.4 RANGE-GATED DOPPLER FILTERS  The delay-line canceler, which can be considered as a time-domain filter, has been widely used  in MTI radar as the means for separating moving targets from stationary clutter. 
 In fact,  pulse-off time may actually be a better indication of the radar  system's maximum design range.   Traditional  radar systems employ a Transmit/Receive (T/R)  switch to allow the transmitter and receiver to share a single  antenn a. The transmitter and receiver take turns using the  antenna. 
 Fog In most cases fog does not actually produce echoes on the radar display, but a very dense fogbank which arises in polar regions may produce asigniﬁcant reduction in detection range. A vessel encountering areas known for industrial pollution in the form of smog may ﬁnd a somewhat higher degree of attenuation than sea fog.. 14Clouds The water droplets which form clouds are too small to produce a detectable response at the 3cm wavelength. 
 A.: Relative Motion in the Terminal Phase of Interception of a Satellite or Ballistic Missile, NACA TN 8399, September 1958. 18. Functional Requirements for the Seasat-A Synthetic Aperture Radar System, Jet Pro- pulsion Lab., FR No. 
 12.11. An Extremely Wideband Receiver.—The receiver shown in Figs. 12.22 and 12.23 isagood example ofadesign forareceiver having a very wide bandwidth. 
 For example, it can be used as a means of target  classification or recognition, as a precision vector miss-distance indicator for uninstritmentsd  targets, as a counter (ECCM) to repeater jammers, as an aid in low-angle tracking, and as a  means for discriminating unwanted clutter or chaff from the desired target.  Tracking in doppler. Tracking radars that are based on CW, pulse-doppler, or MTI principle5  can also track the doppler frequency shift generated by a moving target. 
 SENTATION  INDEPENDENT OF THE EXISTENCE OF SUCH A WAVE AS A REAL OBJECT .EVERTHELESS  THIS DIRECT LINEAR RELATION BETWEEN RADAR CROSS S ECTION AND THE OCEAN 
 /Ê " /"  "ISTATIC ,OCATION  ! BISTATIC RECEIVER TYPICALLY USES RANGE SUM  24   22  FOR TAR 
 BEAM SLOPE  AS A FUNCTION OF ASSOCIATED EDGE TAPERS ( 
 22, pp. 63-68, Jan., 1979. .J . 
 Renau and J. A. Collinson, “Measurements of electromagnetic backscattering from known  rough surfaces,” Bell Syst. 
 The appropriate architecture solution depends upon the radar design constraints.  The number of antenna elements and beamforming requirements are key drivers in the  (a) UHF, low PRF (300 Hz) (b) UHF, higher PRF (2000 Hz)  FIGURE 3. 27 Antenna pointing angles where clutter doppler map to a single doppler filter’s passband ch03.indd   29 12/15/07   6:03:33 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 This 200-MHz radar utilized mechanically adjustable phase shifters to con- trol the relative phase of nine groups of eight dipoles on a 240-ft mast. The re- sulting elevation beamwidth was approximately 1° in width and was phase- scanned over an elevation interval slightly more than 6° in extent. A technique which has seen limited service for radar height finding is a verti- cal receive-only line array mounted on a conventional 2D surveillance radar as shown in Fig. 
 FIGURE 26.15  AREPS height versus range coverage for surface-search radar and small missile target— probability of detection ch26.indd   25 12/15/07   4:53:34 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation. 
 Fox. J. (ed.): " Proceedings of the Symposium on Submillimeter Waves," Polytechnic Press of the  Polytechnic Institute of Brooklyn, Brooklyn, New York, 1971. 
 SCANS FROM AN ANTI 
 155.  17. Sondcrg;~;lrd. 
 Auniform line terminated atany point initscharacteristic impedance behaves asiftheline were infinitely long; there isnoreflection. Power introduced atthe input terminals disappears into the termination with small losses inthe line. However, any discontinuous change along the 1Xfl-... 
 and D. E. Walker: Reflector Surfaces for Communications and Radar Aerials, " Design and  Construction of Large Steerable Aerials," 11tsrirttti011 of Elecrrical Engineers (London) 1EE Corifere~rcr  Prrhlic.crtiorr no. 
 12.3a and b ). The calculated amplitude and phase of the  reflection coefficient are plotted for a smooth sea surface at 100 and 3,000 MHz. It is seen that  the reflection coefficient for vertically polarized energy is less than that for horizontally po­ larized energy. 
 ALARM RATE  !LTERNATIVELY  THE RADAR OUTPUT CAN BE NORMALIZED ON THE BASIS OF THE CLUTTER MAP CONTENT TO OBTAIN AN OUTPUT  ZIXI YI    
 the  itnproven~ent faclor is  Si~nilarly. for a tlor~ldc carlcclcr. wllose average gain is 6, the improvement factor is  A plot of I'q. 
 This implies  that very high antenna towers are often needed, in some cases up to 100 meters. This  exacerbates vertical lobing effects, which may need to be reduced by the use of verti - cal pattern shaping. The long-range requirement often means that greater transmitter  power than that used on shipborne radars is needed, even though VTS antenna gains  can be higher. 
 1One exception tothisstatement must bemade. Echoes from spherical water drops (rain clutter) accurately preserve thepolarization oftheincident wave, andit hasbeen demonstrated that rainclutter canbealmost entirely eliminated bymaking useofthisfact (Sec. 3.10),. 
 Alterna-  tively. A1 + N control signals can be transmitted to the array if an adder is provided at each  phase shifter to corrlbirie the azimuth and elevation phases.  In the sct.io.5-seric.~ ,feet/ each of the M columns of an M by N array utilizes a series  arrangenlent to produce steering in one coordinate (say elevation). 
 ING   GENERALLY FOLLOW THE PRECEPTS DESCRIBED IN 3ECTION  4HE MAIN DIFFERENCE  HERE IS THE AVAILABILITY OF PATH 
 AP-12, pp. 35-43, January, 1964.  138. 
 Timmoneri, Dr. L. Ortenzi, and Dr. 
 TUBE  MODULATOR TO DISTINGUISH IT FROM THE GAS 
 This type of antenna is known as a helisphere . If wide angle scanning in only one plane, i.e., azimuth or elevation, is required, a sim - ilar design called the parabolic torus32 is more applicable. The parabolic torus reflector is  a surface that is spherical in one plane (azimuth or elevation) and parabolic in the other  plane. 
 H.: Optimization of Tilt Angle and Element Arrangement for Planar Arrays, Microwar•e  .I .• vol. 14. pp. 
 The control electrode needs only a short, medium-power  pulse, typically one-third of the anode voltage and one-third of the anode peak current.  Since the control electrode is insulated and since some energy is dissipated on the  control electrode, it can be difficult to cool. This can limit the maximum pulse repeti - tion frequency that can be used. 
 608-621, July 1983. 20. Hansen, V. 
 TION CAUSES MORE DISTORTION )N GENERAL  ERRORS OF THIS NATURE HAVE LITTLE IMPACT ON PERFORMANCE PREDICTION (OWEVER  NEAR 
 IEEE Sens. J. 2018 ,18, 8311–8317. 
 A,: "Aerials for Metre and Decimetre Wave-Lengths," Cambridge Universit~ Press.  London. 1949. 
 TIME ERROR SOURCE  EG   KMH ACCUMULATES  M ERROR PER MINUTE ! RADAR MODE MAY REQUIRE POSITION TO  KM FOR PROPER OPERATION 065 GENERALLY USES THREE OR MORE ANTENNA BEAM POSITIONS IN WHICH IT MAKES A  VELOCITY MEASUREMENT  AS SHOWN IN &IGURE   4HIS MODE DIRECTLY EMULATES DEDI 
 Figure 4.34 compares the results for Lundy Island and the radar training (RT) buoy, both approached from the West. The overall conclusion was that ASV Mk. VI provided a60% increase in detection ranges, which represents about 8.2 dB better sensitivity. 
 This is the  characteristic wave-form of the ‘integrated’ pulse.  FIG. I0  How do we obtain our square wave in the first place?  There are several methods, but one basic system is  interesting because it takes a sine wave and turns it into  . 
 In the optically clear boundary layer, Z values of the order -20 dBZ to 10 dBZ are of interest. In rain, Z may range from about 20 dBZ to as much as 60 dBZ, with a 55 to 60 dBZ rain being of the type that can cause severe flooding. Severe hailstorms may produce Z values higher than 70 dBZ. 
 (6.1 1 ).  46. Westinghouse Brochure: The ARSR-3 Story, no date. 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .556x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 19. D. 
 Ocean. Phys. 2012 ,48, 1006–1013. 
 PULSE CANCELER IMPROVEMENT FACTOR FROM EQUATION   FOR  A LINEAR SYSTEM WITH  .    IS )    N    D" )N &IGURE  B  IT IS SEEN THAT  THIS LEVEL OF  ) IS ACHIEVED FOR MOST OF THE PULSES  WITH ONLY TWO PULSES HAVING VERY  LOW VALUES OF  ) 4HE STATISTICS FOR THE DISTRIBUTION OF  ) FOR THE THREE 
 properly displayed, usuallyonacathode-ray tube(CRT).Timingsignalsarealsosupplied to theindicator toprovidetherangezero.Angleinformation isobtained fromthepointing direction oftheantenna. Themostcommon formofcathode-ray tubedisplayistheplan position indicator, orPPI(Fig.1.3a),whichmapsinpolarcoordinates thelocation ofthe targetinazimuthandrange.Thisisanintensity-modulated displayinwhichtheamplitude of thereceiveroutputmodulates theelectron-beam intensity (zaxis)astheelectronbeamismade tosweepoutward fromthecenterofthetube.Thebeamrotatesinangleinresponse tothe antenna position.AB-scopedisplayissimilartothePPIexceptthatitutilizesrectangular, ratherthanpolar,coordinates todisplayrangevs.angle.BoththeB-scopeandthePPI,being intensity modulated, havelimiteddynamic range.Another formofdisplayistheA-scope, showninFig.1.3b,whichplotstargetamplitude (yaxis)vs.range(xaxis),forsomefixed direction. Thisisadeftectiort':inodulated display.Itismoresuitedfortracking-radar applica­ tionthanforsurveillance radar. 
 The resulting methods can beroughly separated into two classes depending onwhether the reflection ofenergy from the level surface surrounding theradar antenna isimportant tothescheme ofheight-find- ing used. Inthis section are considered methods which doinvolve ground (orsea) reflection; inthe next, free-space beam methods which donot. Iftheantenna ofaradar ofmedium wavelength, forexample, about one meter, isless than about fifty wavelengths above the ground, the reflected energy from the part ofthe beam that strikes the ground will produce maxima and minima intheelevation pattern. 
 119-141, September, 1954.  34. Middleton, D., and D. 
 TO 
 -ARI  h$ESCRIPTION  OF 2!$!23!4 
    .OVEMBER   ( 2 7ARD AND 7  7 3HRADER  h-4) PERFORMANCE DEGRADATION  CAUSED BY LIMITING v IN  %!3#/.   4ECH #ONV 2EC   SUPPLEMENT TO )%%% 4RANS VOL !%3 
   -ARCH   2 " $YBDAL  h2ADAR CROSS SECTION MEASUREMENTS v  0ROC  )%%%  VOL   PP n   !PRIL   2 ' +OUYOUMJIAN AND , 0ETERS  *R  h2ANGE REQUIREMENTS IN RADAR CROSS SECTION MEASUREMENTS v  0ROC )%%%  VOL   PP n  !UGUST   % & +NOTT ET AL  2EF   P   - ! 0LONUS  h4HEORETICAL INVESTIGATION OF SCATTERING FROM PLASTIC FOAMS v  )%%% 4RANS  VOL !0 
 2.3. SAR Raw Data SVD Decomposition When the Xmatrix to be decomposed is the raw SAR data matrix, the row index is the along track direction (azimuth) while the column index represents the slant range. The coherent illumination due to the transmission of the chirp produces very correlated information; in particular, in the azimuth direction the correlated information is the doppler phase history due to the scanning process. 
 Angle coverage--can be 360° in azimuth from a single site, if desired; 60 to 120° is more typical.  Targets-aircraft, missiles, and ships; also nuclear explosions, prominent surface features  (such as mountains, cities, and islands), sea, aurora, meteors, and satr.llites. OTHER RADAR TOPICS 533  Range resolution-could be as low as 2 km, but is more typically 20 to 40 km. 
  3 
 The required dynamic range of the AGC will depend upon the variation in range over  which targets are tracked and the variations expected in the target cross section. If the range  variation were 10 to 1, the contribution to the dynamic range would be 40 dB. The target  cross section might also contribute another 40-dB variation. 
 The noise mainly comes from the side lobes of clutters. During the coherent imaging process of a CSAR image, the value of a pixel from the image is actually affected by the side lobes of pixels around it. For example, a target pixel scatters the wave around θand some clutters around this pixel scatter the wave in other angles. 
 Figure 3a shows the study area, featured at di ﬀerent scales. As Figure 3a shows, the red rectangle outlines the spatial coverage of the selected TerraSAR-X images, while the green rectangle shows the subset for generating the interferometric results. Figure 3b shows the location of the Lungui Highway with the average intensity map as background. 
 #ODED  7AVEFORMS. 
 NEOUS CONDUCTING EARTH HAS BEEN MODELED BY 7AIT  AND +ING  AND THE DISPERSION OF  RECTANGULAR SOURCE PULSES SUGGESTS THAT THE TIME 
 DEFINED MAPS )T IS ALSO COMMONLY USED TO SET RANGE AND BEARING MARKERS ! CONSISTENT COMMON REFERENCE POINT  ##20  TO WHICH ALL RADAR AND OTHER NAVIGA 
 This advection will lead to a temperature inversion at the surface. In  addition, moisture is added to the air by evaporation, producing a moisture gradient to  strengthen the trapping gradient. This type of meteorological condition routinely leads  to a surface duct created by a surface-based trapping condition. 
 These are  (single canceler) (4.34)  (double canceler) (4.35)  These are plotted in Fig. 4.31.  A stepped-scan antenna that dwells at a particular region in space, rather than scan  continuously, also is limited in MTI performance by the finite time on target t0• The time  waveform is constant so that it will have a different spectral shape and a different improvement  factor than that produced by the gaussian beam assumed in the above. 
 Harmon, “Track before detect performance for a high PRF search mode,” in IEEE National  Radar Conference  1991, pp. 11–15. 71. 
 OF 
 Valcn7llela. G. R .. 
 157. Sensors 2018 ,18, 3750 In order to obtain the target images of each channel, the problem of interferometric near-ﬁeld imaging can be converted into an optimization and reconstruction problem of two independent channels according to CS theory and sparse space distribution characteristics of the target scene: /braceleftBigg min/bardblg1/bardbl0s.t./bardbls/prime 1−A/prime 1g1/bardblF≤ξ1 min/bardblg2/bardbl0s.t./bardbls/prime 2−A/prime 2g2/bardblF≤ξ2(15) where,/bardbl•/bardbl0refers to the zero norm of vector, namely the number of non-zero elements in the vector, /bardbl•/bardblFrefers to the Frobenius norm of matrix, and ξiis a positive number which depends on the noise level. In Formula (15), it is quite important to select an appropriate noise level for the ﬁnal optimization result: too high noise level will lead to the loss of some weak scattering points, while too low noise level will make it difﬁcult to suppress strong noises. 
 Three clutter cell cases are usually of interest: bcamwidth-limited, range-limited, and doppler-limited. Deamwidth-Limited Clutter Cell Area. The beamwidth-limited clutter cell area (Ac)b is the bistatic footprint. 
 NOISE  RATIO FOR A SIGNAL RECEIVED IN WHITE NOISE 4HE MATCHED FILTER FREQUENCY RESPONSE FOR   A SIGNAL UT  IS    (FK 5 F EJF T MF   
 SBX’s floating platform, a modified oil-drilling vessel, was designed for  FIGURE 13.49  THAAD radar ( Courtesy of Raytheon Company ) ch13.indd   68 12/17/07   2:41:15 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 The length of the strip is a linear function of the differential delay required, but the band- width is independent of length. The differential delay corresponds to the timeAluminum strip delay line Steel strip delay line All-pass network Perpendicular diffraction delay line Surface-wave delay line Wedge-type delay line Folded-tape meander line Waveguide operated near cutoff YIG crystalB, MHz 1 20 40 40 40 250 1000 1000 1000T, >xs 500 350 1000 75 50 65 1.5 3 10BT 200 500 300 1000 1000 1000 1000 1000 2000/o, MHz 5 45 25 100 100 500 2000 5000 2000Typical loss, dB 15 70 25 30 70 50 25 60 70Typical spuri- ous, dB -60 -55 -40 -45 -50 -50 -40 -25 -20 . separation between the initial frequency and the final frequency of the waveform and is usually equal to the expanded pulse width T. 
 The dot product of each of these unit vectors with J gives the field in the main and cross-polarized directions. This pattern solution is found by a compromise between the number of grid regions and the time to compute all the parameters for each grid point. When the pattern is desired far off the pattern peak, one must consider the artificial grating lobes created by the computation method itself, in which case the grid density must be increased. 
 Figure 23.6 is a photograph of the S (10-cm)- and X (3-cm)-band polarization-diverse doppler radar operated by the National Center for Atmospheric Research (NCAR). The system permits simultaneous measurements of the reflectivity factor on 2 wavelengths—the doppler parame- . FIG. 
 408 lNTRODUCTION TO RADAR SYSTEMS  For a bandwidth-limited "rectangular" pulse as described by Fig. 11.5, the value of a2 is  cos nBr - 3 8(cos nBr - 1) 2 sin nBr - -- - -  n2r2 nBr (n BT)~ (~BT)~ + Si (~BT)  a2 = -  3 Si (~BT) + (cos nBr - l)/nBr (1 1.30)  In the limit as Br -, co, the value of a2 approaches n2r2/3, which is the same as that obtained  for the perfectly rectangular pulse.  The value of a2 for a perfectly rectangular pulse is finite even though its value of b2 is  infinite. 
 The limit  on ISCR (dB) is I (dB) plus target integration gain (dB).FIGURE 2.78  Composite adjustments and adjusted phase-noise spectral density TABLE 2.4  Integration of the Phase-Noise Spectral Density of Figure 2.76 with Adjustments of  Figure 2.77 as Shown in Figure 2.78 Segment f1, Hz f2, HzSlope,  dB/dekSlope   a S1 dBc/Hz S2 dBc/HzIntegrated  powerIntegrated  power, dBc 1 1 90  30.0  3 –149.4  –90.8 0.188e-7 –77.25 2 90 365 –10.0 –1  –90.8  –96.9 0.105e-6 –69.80 3 365 1,000 –30.0 –3  –96.9 –110.0 0.323e-7 –74.91 4 1.0e3 1.0e4 –20.0 –2 –110.0 –130.0 0.900e-8 –80.46 5 1.0e4 5.0e5   0.0  0 –130.0 –130.0 0.490e-7 –73.10 6 5.0e5 1.0e7 –40.0 –4 –130.0 –182.0 0.167e-7 –77.78 Total integrated noise power 0.231e-6 –66.37 ch02.indd   70 12/20/07   1:45:49 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 7 .4 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 are shown in Figure 7.2, where a normalized standard deviation is plotted against the  midbeam S/N. This result holds for a moderate or large number of pulses integrated,  and the optimal estimate involves finding the location where the correlation of the  returned signal and the derivative of the antenna pattern is zero. Although this esti - mate is rarely implemented, its performance is approached by simple estimates. 
 Conopulse. Conopulse (also called scan with compensation) is a radar tracking technique that is a combination of monopulse and conical scan.23'24 A pair of antenna beams is squinted in opposite directions from the antenna axis and rotated like a conical-scan-radar beam scan. Since they exist simul- taneously, monopulse information can be obtained from the pair of beams. 
 The PSLR/ISLR before the autofocusing 194. Sensors 2019 ,19, 2161 are−6.26 dB and −2.33 dB in Figure 12a. After the minimum-entropy autofocusing the PSLR/ISLR become−10.76 dB and −5.65 dB, respectively. 
 2ECEIVER /NLY #/43 #OMMERCIAL /FF 4HE 3HELF #2) #OHERENT 2EPEATER )NTERFERENCE #2," #RAMER 
 CORRELATED WITH A SAMPLE OF THE TRANSMITTED SIGNAL 4HE RANGE OF THE TARGET IS GIVEN BY THE TIME POSITION OF THE CROSS 
  %23 
 mode without the need  for straps. Since tlielc are no straps, the rising-sun geometry is more suitable for the shorter  waveletlgt hs than are coriveti tiorial resonators.  ('oauial magnetron. 
 For an aircraft, the span of the wings, the fuselage length, the tail and elevator span,  the vertical stabilizer and rudder height, and their relative locations are the main  features that influence the RCS. Target shaping on a scale size much less than a  wavelength will have little effect. Accurate measurements of radar scattering at HF  frequencies is challenging, but facilities for making scale model measurements are  ch20.indd   26 12/20/07   1:15:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 RANGE  SOLID 
 46  BROADCAST TRANSMITTER  THE LATTER TWO CONFIGURED FOR AIR SURVEILLANCE %XAMPLES OF  0"2S OPERATING WITH COOPERATIVE COMMUNICATIONS TRANSMITTERS IN THE RECEIVER 
 CONSTANT VERTICAL DIS 
 14, 17, and 25. Briefly, available power at an output port is that which would be delivered to a load that matches (in the complex-conjugate sense) the impedance of the source. Available gain of a two-port transducer or cascade of transducers is the ratio of the available power at the output port to that available from the source connected to the input port, with the stipulation that the available output power be mea- sured with the actual input source (not necessarily impedance-matched) con- nected. 
 no. 76 CH 1151-OED.  49. 
 the- chemical structure does, in fact, change in -  opacity under the impact of the beam. A beam of light —  is passed through the tube end, and projected by rela-  tively simple optical means on to a ground-glass screen.  The radar display drawn out by the electron pencil is  thus enlarged up to the size of the screen. 
 ch13.indd   14 12/17/07   2:39:31 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 it  is seen in the tahlc that the 4-face array requires the fewest clements. However, if the beam­ widths at the maximum scan are to be the same, the 6-face array requires the fewest total  number of elements. When the criterion is to maintain either the average gain or the average  heamwidth the same over the scan, the 4-face array yields the minimum total number of  elements. 
 lEE(London) Conf. Puhl.no.155. 78.Currie:N.C..F.B.DyerandG.W.Ewell:Characteristics ofSnowatMillimeler Wave1engtlls. 
 The log IF performs essentially as an instantaneous AGC, giving the desired constant  angle-error sensitivity of the difference signals normalized by the sum signal. The  detected ∆ information is a bipolar video where the error information is contained in  the sinusoidal envelope. This signal is separated into its two components, azimuth-  and elevation-error information, by an angle demodulation. 
 FACE TO TARGET  "Y A LOBED STRUCTURE  WE MEAN THAT THERE WILL BE REDUCED COVERAGE AT SOME ELEVATION ANGLES NULLS  AND INCREASED SIGNAL STRENGTH AT OTHER ANGLES LOBES  ! CHANGE IN FREQUENCY WILL CHANGE THE LOCATION OF THE NULLS AND LOBES SO THAT BY OPERATING OVER A WIDE FREQUENCY RANGE  THE NULLS IN ELEVATION CAN BE FILLED IN  AND THE RADAR WILL BE LESS LIKELY TO LOSE A TARGET ECHO SIGNAL &OR EXAMPLE  MEASUREMENTS WITH A WIDEBAND EXPERIMENTAL RADAR KNOWN AS 3ENRAD  WHICH COULD OPERATE FROM  TO  -(Z  SHOWED THAT WHEN ONLY A SINGLE FREQUENCY WAS USED  THE BLIP 
 56-60, 1961. (Reprinted in ref. 18.)  26. 
 RANGE  THREE 
 42.Rarton. D.K..andShrader, W.W.:Intcrc1utter Visibility inMTISystems, IEEEEasconRecord. 1969.pr.294297. 
 BASED SEARCH AND TRACK RADAR $ AZIMUTH ELECTRONIC SCANNING SUFFICES FOR SOME OF THESE APPLICATIONS  #LASSIFICATION OF 2EFLECTOR !NTENNAS  2ADAR REFLECTOR ANTENNAS CAN BE CLASSIFIED IN  VARIOUS WAYS /NE USEFUL CLASSIFICATION CRITERIA IS ELECTRICAL DESIGN  IE  THE REFLECTOR OPTICS CONFIGURATION 4ABLE  PROVIDES A SUMMARY LEVEL COMPARISON OF SOME COMMON RADAR   3INGLE 2EFLECTOR  0ARABOLIC#YLINDRICAL 2EFLECTOR $UAL 2EFLECTOR #ASSEGRAIN OR 'REGORIAN #ONFOCAL 0ARABOLOIDS3PHERICAL AND 4ORUS %LECTRONIC 3CANNING%SCAN s  ,IMITED IN BOTH  !ZIMUTH AND %LEVATION s  !CHIEVED VIA  &EED SWITCHINGs  7IDE $  SCANNING s  5SES %3!  LINE SOURCE FOR WIDE $ SCANNINGs  ,IMITED IN BOTH  !ZIMUTH AND %LEVATION s  !CHIEVED VIA  FEED SWITCHINGs  5SES PLANAR  %3! SOURCE s  4YPICALLY  LIMITED  BUT TRADABLE BY VARYING MAGNIFICATIONs  0OTENTIAL FOR  VERY WIDE $ SCANNING TORUS  OR $ 3CANNING SPHERICAL  s  !CHIEVED VIA  FEED SWITCHING  !PERTURE %FFICIENCY&EED 4YPES s  -EDIUM TO HIGHs  .O ESCAN 3INGLE  HORN s  %SCAN !RRAY  SWITCHED FEEDS s  -EDIUM TO HIGH s  $ %3! LINE   SOURCEs (IGHs  .O ESCAN   3INGLE HORN s  %SCAN !RRAY  SWITCHED FEEDS s (IGHs  $ %3!  PLANAR SOURCEs  -ODEST TO LOWs  3WITCHED  BEAM ARRAY ON CIRCULAR ARC TORUS REFLECTOR  OR SPHERICAL ARC SPHERICAL REFLECTOR  "LOCKAGE #ONCERNSs  -ITIGATE FEED  BLOCKAGE VIA OFFSET GEOMETRYs  -ITIGATE FEED   BLOCKAGE VIA OFFSET GEOMETRYs  -ITIGATE FEED  BLOCKAGE VIA  OFFSET GEOMETRY s  #AN MOVE FEED  BEHIND REFLECTORs   -ITIGATE FEED  BLOCKAGE VIA OFFSET GEOMETRYs  3ERIOUS  CONCERN FOR VERY WIDE SCAN CONFIGURATIONS 4!",%  #OMPARISON OF +EY &EATURES OF 2EFLECTOR !RCHITECTURES.   2%&,%#4/2 !.4%..!3   £Ó°Î REFLECTOR ARCHITECTURES FROM THIS PERSPECTIVE -ORE DETAILED DISCUSSIONS OF THE CHARACTERIS 
 This implies that an equation can be written with pulse length in the numerator rather than with bandwidth in the denom- inator. North also showed that signal detectability is improved by integrating successive signal and noise samples in the receiver and that the detectability is a function of the total integrated signal energy. (The integration process is dis- cussed in Sec. 
 h~any other functions, some ofwhich will appear inlater sections, are performed bythe timer incomplex situations. The functions ofthose indicator circuits not included inthe timer vary widely with thedifferent display types. For illustrative purposes, Fig. 
 An equally valid def- inition of the RCS results when the electric-field strengths in Eq. (11.1) are re- placed with the incident and scattered magnetic-field strengths. It is often neces- sary to measure or calculate the power scattered in some other direction than back to the transmitter, a bistatic situation. 
 The crit-ALLOWABLESPEEDGATE SEARCHRANGE APPROX 40 kHz FEEDTHROUGH CLUTTER (MAIN LOBE)2D HARMONICOF CLUTTER3D HARMONIC OFCLUTTER FREQUENCY (kHz) (a) ALLOWABLE SPEEDGATE SEARCH RANGE (NOT LIMITED BY HARMONICS) CLUTTER FEEDTHROUGH2D HARMONICOF CLUTTER . FIG. 19.7 Offset video receiver block diagram. 
 J2 I J2X. 1956.  5. 
 The doppler frequency is initially of high value,  decreases to zero beat, and then increases again. When this signal is recorded on film the  rcsu lting intensity modulation is a one-dimensional hologram, or Fresnel zone-plate, and has  focusirlg properties. If the film were illuminated by a coherent, collimated beam of light like  that from a laser. 
 2.26a.  Target A i~ located within the maximum unambiguous range Runamb [Eq. (1.2)] of the radar,  target B is at a distance greater than Runamb but less than 2Runamb, while target C is greater  than 2Runarnh but less than 3Runarnh. 
 In this case, discrete-time  convolution is done in the time domain by convolution of the complex envelope input  sequence following digital down-conversion with the matched filter impulse response  sequence. Because time-domain convolution can be computationally intensive, a more  economical approach from a computational standpoint is shown in Figure 8.27 b, in  which frequency-domain processing is used to implement the convolution. The frequency-domain digital pulse compression processor operates on the princi - ple that the discrete Fourier transform (DFT) of the time convolution of two sequences  is equal to the product of the discrete Fourier transforms of each of the sequences. 
 [ CrossRef ] 6. Reinisch, B.W.; Galkin, I.A. Global ionospheric radio observatory (GIRO). 
 15. Lee, Y. W.: Application of Statistical Methods to Communication Problems, MIT Research Lab. 
 The -103-dB (double sideband at 10 kHz) transmitter used as an example above has a peak deviation of 0.1 Hz. These numbers are all equivalent only when referred to a particular band- width, 1 kHz in this case. (The description in hertz is convenient only when the noise is expressed in the bandwidth of interest in a particular radar.) The concept of a peak signal is properly associated only with a sine wave. 
 51. 388 INTRODUCTION TO RADAR SYSTEMS  10.7 AUTOMATIC DETECTION  The function of the radar operator viewing the ordinary radar display is to recognize the  presence of targets and extract their location. When the function is performed by electronic  decision circuitry without the interventiotl of an operator, the process is known as u~cton~c~tic  detection. 
 PLANE DATA IS SHOWN IN BOLD TYPESEE SUBSEQUENT TEXT    AFTER - - 7EINER  #HAPTER   COURTESY 3CI4ECH .   ")34!4)# 2!$!2   ÓÎ°Óx9EAR  REPORTED2EF  /RGANIZATION !UTHOR 3URFACE #OMPOSITION $ATA  #URVES   &IGURES&REQUENCY  '(Z -EASUREMENT !NGLES DEGREES  0OLARIZATION      PI     PS    E      4HE 5NIVERSITY  OF -ICHIGAN %2)- ,ARSON  (EIMILLER  ET AL 'RASS WITH CEMENT TAXIWAY  7EEDS AND SCRUB TREES/RCHARD  WEEDS  SCRUB  TREES W SNOW COVER                    (( (6   (( (6 (( (6 n            n        n      n   n  n   n   n   n   n   n     2AYTHEON #O  7AYLAND  -!#ORNWELL  ,ANCASTER "EACH AND SAND DUNES3EA SEA STATE  .ONE  66 ,OW GRAZ  ANGLE,OW GRAZ ANGLE A   n     'EORGIA )NST OF 4ECH %%3%WELL  :EHNER 3EA  
  
 The monolithic approach to circuit design inherently offers  several advantages: ● Low-cost circuitry  Component assembly is eliminated because complex circuit  configurations using both active and passive components are batch processed on the  same substrate. ch11.indd   24 12/17/07   2:25:35 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 21.3. The components that determine the radiated waveform are shown within the dotted lines in the upper left-hand corner of the diagram. This equipment consists of two stable oscillators. 
 157-158 andamplitude fluctuations, 168 andanglefluctuations. 169 inmonopulse. 164 Automobile, radarcrosssectionof,44 Az-e!mount,271 Bsandwich radome, 267 Balanced duplexers. 
 Dull, “MPRF Interpulse Phase Modulation for Maximizing Doppler Clear  Space,” U.S. Patent 6518917, 2/11/2003. 64. 
 Two cases are recognized, depending whether the incident field is polarized parallel or perpendicular to the edge. The diffracted field is given by the formula Y Jks JTT/4 Ed= (X+Y) (11.21) VT/nks sin p where T is a divergence factor, X and Fare diffraction coefficients, (3 is the angle between the incident ray and the edge, and s is the distance to the observation point from the point of diffraction. The difference of the two diffraction coeffi- cients is used when the incident electric field is parallel to the edge (TM polar- ization) and the sum when the incident magnetic field is parallel to the edge (TE polarization). 
 Ausherman, D. A.: Digital versus Optical Techniques in Synthetic Aperture Radar (SAR) Data Processing, Opt. Eng., vol. 
 This page has been reformatted by Knovel to provide easier navigation. Contents     xxiii   Depth of First Null in Ve locity Respons e  ............  15.40  15.10 Improvement Factor Restriction Caused by  Limiting  ................................................................... 
 FIXED  CONSPICUOUS RADAR TARGET #HART 2ADARS  4HE CAPABILITY AND RELATIVELY LOW COST OF MODERN PROCESSING AND  DISPLAY SYSTEMS ALLOW GREAT FLEXIBILITY IN THE PRESENTATION OF INFORMATION TO USERS &OR  MANY YEARS  3/,!3 
 NOISE AMPLIFIER ,.!  AND SUBSEQUENTLY DOWNCONVERTED THROUGH ONE OR MORE INTERMEDIATE FREQUENCIES )&  BY MIXING WITH STABLE LOCAL OSCILLATORS ! BANDPASS )& LIMITER AT THE RECEIVER OUTPUT PROTECTS THE !$ CONVERTER FROM DAMAGE BUT ALSO PREVENTS LIMITING FROM TAKING PLACE IN THE !$ CONVERTER )N EARLY -4) SYSTEMS  THE )& LIM 
 ÓÎ°Îä  2!$!2 (!.$"//+  7AVEFORMS 4HE EFFECTIVE RADIATED POWER %20  OF BROADCAST TRANSMITTERS  CAN VARY  FROM A MAXIMUM OF ^ -7 FOR 46 TRANSMITTERS TO A MINIMUM OF ^ 7 FOR CELL 
 Most detector laws  approximate either a linear or a square-law~characteristic. In the linear detector the output  signal is directly proportional to the input envelope. (Actually, the so-called linear detector is a  nonlinear device, or else it would not be a detector.) Similarly, in the square-law detector, the  output signal is proportional to the sciuare'of the input envelope. 
 I'tte log-normal probability density function has been proposed to model the clutter  echo with very high-resolution radar and at the higher sea states. If the clutter cross section  is log normal, the probability density function describing its statistics is  1 1 p(ac)= . exp[-i(ln)2 aC>0 (13.1 la)  J2n on,  1 where a, = clutter cross section  a, = median value of a,  a = s-tandard deviation of In a, (natural logarithm)  The probability density function that describes the statistics of the voltage amplitude at the  output of the envelope detector when Eq. 
 The receiver input can simply be  the mixer stage, especially in military radars that must operate in a noisy environment.  Although a receiver with a low-noise front-end will be more sensitive, the mixer input can  have greater dynamic range, less susceptibility to overload, and less vulnerability to electronic  interference.  The mixer and local oscillator (LO) convert the RF signal to an intermediate frequency  (IF). 
 MICRORADIAN PRECISION    
  
 Inc .. New York,  1949.  6. 
 However, the same radiating element collects and radiates after reflection.  Ample space for phase-shifter control circuits exists behind the reflector. To avoid  aperture blocking, the primary feed may be offset as shown. 
 E. Ryan, C. P. 
 Clutter Map Automatic Gain Control. In some radars, mountain clutter can create echoes which would exceed the dynamic range of the subsequent stages of the receiver (A/D converter, etc.) if the STC attenuation at that range allows detection of small aircraft. The spatial area occupied by such clutter is typically a very small fraction of the radar coverage; so AGC is sometimes considered as an alternative to either boosting the STC curve (a performance penalty affecting detectability of small aircraft in areas of weaker clutter or no clutter) or increasing the number of bits of the A/D converter and subsequent processing (an economic penalty). 
 April.1962. 27.Kroszcynski,J.J.: PulseCompression byMeansofLinear-Period Modulation, Proc.IEEE,vol.57,pp. 126O-1266,July.1969. 
 E. Uhlenbeck (eds.): "Threshold Signals," MIT Radiation Laboratory Series,  vol. 24, sec. 
 Puhl. no. 155. 
 ART  RADAR  RECEIVERS ARE OFTEN CLASSIFIED AS EITHER WIDEBAND OR HIGH DYNAMIC RANGE $IFFERENT RADAR FUNCTIONS PUT A GREATER EMPHASIS ON ONE OR THE OTHER OF THESE PARAMETERS &OR EXAMPLE  IMAGING RADARS PUT A PREMIUM ON WIDE BANDWIDTH  WHEREAS PULSE DOPPLER RADARS REQUIRE HIGH DYNAMIC RANGE "ECAUSE RADARS ARE OFTEN REQUIRED TO OPERATE IN A VARIETY OF MODES WITH DIFFERING BANDWIDTH AND DYNAMIC RANGE REQUIREMENTS  IT IS NOT UNCOMMON TO USE DIFFERENT TYPES OF !$ CONVERTER  SAMPLING AT DIFFERENT RATES FOR THESE DIFFERENT MODES $ATA &ORMATS  4HE MOST FREQUENTLY USED DIGITAL FORMATS FOR !$ CONVERTERS ARE  S COMPLEMENT AND OFFSET BINARY  4HE S COMPLEMENT IS THE MOST POPULAR METHOD OF DIGITAL REPRESENTATION OF SIGNED  INTEGERS AND IS CALCULATED BY COMPLEMENTING EVERY BIT OF A GIVEN NUMBER AND ADDING ONE . È°ÎÈ  2!$!2 (!.$"//+  4HE MOST SIGNIFICANT BIT IS REFERRED TO AS THE SIGN BIT )F THE SIGN BIT IS   THE VALUE IS POSI 
 26. Harvey, D. H., and T. 
 provides coverage of tlle elevation sector with the equivalent of parallel  rcceivitig beams. The elevation angle of tlie target is determined by which receiver is excited.  'I'his teclirtiquc lias beer1 called witllirr-l~lrlsc' scanning. 
 Sensors 2019 ,19, 3344 In the present work only one microburst was applied for aperture synthesis. The author states all microbursts can be used for inverse aperture synthesis in order to improve the image quality through a superposition of all images obtained for each microburst inside the main pulse. In addition, a new ISAR procedure can be developed based on the whole structure of the main pulse. 
 18.3 Conical-scan tracking. AZIMUTH SERVO CHANNEL FIG. 18.4 Block diagram of a conical-scan radar. 
 Salisbury, W. W.: The Resnatron, Electronics, vol. 19, pp. 
 30. Martorella, M.; Acito, N.; Berizzi, F. Statistical CLEAN technique for ISAR imaging. 
 W .. Jr., and K. M. 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.436x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 mounted on the aircraft’s wingtip as far apart as possible. The signals received in each  wingtip antenna are repeated in the opposite wingtip antenna, except for a 180 ° phase  shift, which is inserted in one line to direct an interferometric null toward the victim  radar. 
 GENCE OF %#$)3 AND RADAR DISPLAYS #ERTAINLY  THIS IS TRUE AT A BASIC DESIGN LEVEL  BUT )-/ IS KEEN TO DIFFERENTIATE BETWEEN THE TWO !N %#$)3 IS USED TO PLAN AND MONITOR PASSAGES A RADAR IS USED PRIMARILY AS A COLLISION AVOIDANCE TOOL BUT ALSO TO AID POSI 
 The geometrical features of refocusing ship05 and ship06. ( a) Lengths of ships; ( b) Widths of ships. ( c) Areas of ships. 
 LINED EARLIER &URTHERMORE  INTERFERENCE FROM THE HOST EMITTER  AND OTHER EMITTERS  ESPE 
 11.5. Since longitudinal currents cross the junction plane onboth inner and outer conductor, good contact must beassured. For theouter conductor this isdone bypulling together two mating cones ofdiffering taper by means ofthe strong outer clamping rings. 
 (2)wegetfortheallowable rate ofdrift of frequency df= 1 z100Tt,”(3) For example, this has the value 20kc/see’ forT=1000~sec(PRF of 1000) and t,=500 psec (target atrange of50miles). Itwill beseen later that such alow rate ofdrift cannot beobtained inalocal oscillator without some special means ofstabilization. Inthecase ofthecoherent oscillator, ontheother hand, thefigure isreadily attainable with awell- constructed oscillator circuit.. 
 SIONS OF hNO DETECTIONv AND hTARGET DETECTION v RESPECTIVELY 4HE BLANKING COMMAND IS  DELIVERED WHEN ( IS DETECTED 3," PERFORMANCE CAN BE EXPRESSED IN TERMS OF THE FOLLOWING PROB ABILITIES I  4HE  PROBABILITY  0" OF BLANKING A JAMMER IN THE RADAR SIDELOBES  WHICH IS THE PROBABILITY OF  ASSOCIATING THE RECEIVED SIGNALS  U  V  WITH ( WHEN THE SAME HYPOTHESIS IS TRUE  0"  IS A FUNCTION OF THE JAMMER 
 It  may need to be combined with data from a number of radar heads and, therefore, will  be quite synthetic when displayed on operators’ screens, reducing the possibilities of  individual operator adjustment. Extensive data communications networks become a  critical aspect in the performance of the VTS. High reliability of the system is required  because of safety, environmental protection, and security aspects. 
 In transmit mode, the antenna launches a guided wave  from the transmitter into free space and typically focuses this radiated energy over a  limited angular range or beamwidth. In receive mode, the reflector antenna operates in  a reciprocal manner, receiving reflected radar target energy, i.e., echoes, from a limited  angular range. These received echoes are then converted into guided waves that are  amplified and subsequently processed in the radar receiver. 
 Furthermore  the fibrous-glass-reinforced laminate took about two minutes to dry but the air-inflated  radome material required about 30 to 45 min.  The losses due to rain can be reduced significantly by treating the radome surface to make  it non wetting, or water repellent.119 121 Experiments at 4.2 GHz with a 55-ft rigid metal  space-frame radome at a simulated rain rate of 40 mm/h (a very high rate) had a measured loss  of from 1.0 to l.7 dB.119 When treated to decrease its wettability the loss was less than 0.3 dB.  The theoretical loss calculated by the method described by Blevis was 3.4 dB. 
 WAVELENGTH SYSTEMS ATTEMPTING TO  ACHIEVE HIGH UNAMBIGUOUS VELOCITIES 'ENERALLY SPEAKING  MOST METEOROLOGICAL DOP 
 ON OF THE  HIGH 
 3  )NT -ICROWAVE 3YMP  )%%% #( 
 Lower first sidelobes require a highly tapered aperture illumination, one with the  illumination at the edge of the aperture considerably less than that at the center. It is not easy to  obtain with a reflector antenna the precisely tapered aperture illuminations necessary for low  sidelobe radiation. Because of its many radiating elements, an array antenna is better suited for  achieving the low-sidelobe aperture illumination than is a reflector. 
 FORMER TO PROVIDE A GOOD MATCH BETWEEN A SOURCE OF POWER AND FREE SPACE )F THE  ANTENNA IS NOT MATCHED TO FREE SPACE  POWER WILL BE REFLECTED BACK TOWARD THE GENERA 
 The spectral convolution on line 6 corresponds  FIGURE 25.8  Analog downconversion in the frequency domain 0 MHz75 MHz 1. Real IF signal 2. Frequency shifting   (–75 MHz complex   tone) 3. 
 Ê76 
 94. Dunbar, A. S.: Calculation of Doubly Curved Reflectors for Shaped Beams, Proc. 
 SPECIFIC POST PROCESSING )N CONTRAST TO AIRBORNE SYSTEMS  THE DYNAMICS OF MOST SPACECRAFT ARE SUCH THAT NO  MOTION COMPENSATION IS REQUIRED FOR SPACE 
 STATE TRANSMITTERS 4HE READER IS REFERRED TO 3ECTION   #HAPTER   AND 3ECTION  FOR FURTHER INFORMATION ABOUT THIS IMPORTANT APPLICATION OF SOLID 
 3 $ATA  ,INKn n n n n n n KnK &)'52%  4YPICAL ! 
 PHASE AND QUADRATURE )1  4HE ANALOG 
 Performance chartandRiekediagram. Fourparameters determine theoperation ofthe magnetron. l'heseare(1)themagnetic field,(2)theanodecurrent, (3)loadconductance, and Figure6.5Photograph oftheSFD-319 KG­ bandfixedfrequency invertedcoaxialmagnet­ ron.Thistubedeliversapeakpowerof100kW witha0.005dutycycleatafrequency between 34,512and35.208GHz.Theefficiency is about25percent.(Courtesy Varia"Associ- ates,Inc.,Beverly,MA.). 
 R. W. P .. 
 The theory is based on two approximations in the application of Eqs. (11.9) and (11.10), both of which are reasonably effective approximations in a host of practical cases. The first is the far-fleld approxima- tion, which assumes that the distance from the scattering obstacle to the point of observation is large compared with any dimension of the obstacle itself. 
 6 Ê-9-/ 
 Ewell: Radar Seaclutter at 9.5. 16.5, 35, and 95 GHz, 1974 IEEE  Arrr tvrrrus ur~d Propugof io/i Socirfy Symposiii~n, June 10-.I 2. 1974, pp. 
         &)'52%    !'# IN MONOPULSE TRACKING.   42!#+).' 2!$!2   °££ #OMPLEX TARGETS CAN CAUSE OTHER PHASE RELATIONS AS A PART OF THE ANGLE SCINTILLATION  PHENOMENON 4HE ABOVE ERROR VOLTAGE  PROPORTIONAL TO THE RATIO OF THE DIFFERENCE  SIGNAL DIVIDED BY THE SUM SIGNAL  IS THE DESIRED ANGLE 
 SPAWNED REFLECTIONS OF SURFACE TRAVELING WAVES THAT MIGHT BUILD UP ALONG THE WINGS LEADING EDGES !NOTHER IS THE USE OF THIN ABSORBER COATINGS THAT ARE SERRATED AROUND THE EDGES OF HATCHES  COVERS  AND CANOPIES TO SUPPRESS REFLECTIONS FROM EDGE DISCONTINUITIES 9ET ANOTHER IS THE FACT THAT THE " 
 OF 
 t 111 . 102 INTRODUCTION TO RADAR SYSTEMS  Description of operation. A simple CW radar such as was descrihed in Sec. 
 Pure  Appl. Math. , vol. 
 Most models have this nondeviative absorption as a median value plus a distribution. 2. E region: This ionization region extends between about 90 and 130 km in altitude with a maximum near 110 km when sunlit. 
 Such a phase error, for example,  might be caused by a deformation of the surface from its true value.Ruze101 showed in a simple  derivation that the gain of a circular aperture with arbitrary phase error is approximately  G = G0(1 -P) (7.30) . RADAR ANTENNAS 263  where G0 is the gain of the antenna in the absence of errors, and 1J is the phase error, in radians,  calculated from the mean phase plane. This simple expression is valid for any aperture illumin­ ation and renector deformation. 
 TION  AND ELIMINATING THAT DETECTION AND TRACK ROW AND COLUMN  FROM THE TABLE 4HIS PROCESS IS REPEATED UNTIL THERE ARE EITHER NO TRACKS OR NO DETECTIONS LEFT !PPLYING THIS ALGORITHM TO 4ABLE  RESULTS IN DETECTION NO  UPDATING TRACK NO   DETECTION NO  UPDATING TRACK NO   AND TRACK NO  NOT BEING UPDATED "ETTER ASSIGNMENTS ARE POSSIBLE WITH MORE SOPHISTICATED PROCESSING ALGORITHMS 4HE THREE TYPES OF MORE SOPHISTICATED ALGORITHMS MOST FREQUENTLY USED ARE   'LOBAL .EAREST .EIGHBOR '..   #ONSIDER THE WHOLE MATRIX OF STATISTICAL DIS 
 Two schemes involving theuseofapartially reflecting mirror toplace avirtual image ofascreen inoptical superposition with thedis- play areillustrated inFigs. 7.4and 75. The device ofFig. 
 £Ó°£ä  2!$!2 (!.$"//+  &IGURE  ALSO SHOWS THAT FEED BLOCKAGE INCREASES THE SIDELOBE LEVEL FOR EXAMPLE   WITH A n D" EDGE TAPER  ONE OBTAINS n D" SIDELOBES RATHER THAN  
 shown at(a)and(c). FIc.6.12.—Three-dimensional displays. A,B,andCaretargets, dimensional displays [asdistinguished from error indicators (Sec. 
 Avoltmeter will certainly work, but experience has shown that aspeaker orpair of earphones, inconjunction with the operator’s hearing sense, ismuch more effective provided the frequencies tobedetected lieinthe range between afew hundred and afew thousand cycles persecond. 1Within this range, the ear easily recognizes pure tones inthe presence ofhiss even when thepure note ismuch tooweak tobeseen onanoscillograph. This phenomenon isanalogous tothe averaging performed bythe eye when looking atanA-scope, asdiscussed inChap. 
 Optimal Binary Codes.  Optimal binary codes are binary sequences whose peak  sidelobe of the aperiodic autocorrelation function is the minimum possible for a given  code length. Codes whose autocorrelation function, or zero-doppler response, exhibit  low sidelobes are desirable for pulse compression radars. 
    
 DICULAR TO EACH OTHER 4HOSE REDUCTIONS DEPEND ON THE SIZE OF THE FACES EXPRESSED IN WAVELENGTHS   4HE 2#3 OF MOST OF THE SIMPLE SCATTERING FEATURES DISCUSSED IN THIS SECTION MAY BE  ESTIMATED BY USING THE SIMPLE FORMULAS LISTED IN 4ABLE  4HE 2#3 OF SOME COM 
 Range gate straddle loss can be  reduced by the use of overlapping gates at the expense of extra hardware and process - ing. The rightmost plots represent the use of 50% range gate overlap ( ts = tg/2). The  maximum pulse matched filter output as a function of return delay is shown in terms of  relative voltage and power. 
 ANGLE FIG. 11.10 Measured RCS of a 15° half-angle cone (vertical polarization). The base circumfer- ence is 12.575X. 
 40. Brown, N. J.: Modern Receiver Protection Capabilities with TR-Limiters, Microwave}., vol. 
 The a-ccomponent ofcur- rent inthe coil isatany instant given by. 542 THE REG’EI VI.VG SYSTE,JI—I.VDICA TORS [SEC. 13.17 and istherefore proportional tothetime integral ofE.When Ereaches the desired maximum value, theswitch isclosed and V1isdisconnected. 
 Thelimitofmequaltoinfinitycorresponds tothenonftuctuating target. Thechi-square distribution isamathematical modelusedtorepresent thestatistics ofthe fluctuating radarcrosssection.Thesedistributions mightnotalwaysfittheobserved data,but theyarefairapproximations inmanycasesandareusednevertheless forconvenience. The chi-square distribution isdescribed bytwoparameters: theaverage cross sectionanandthe number ofdegrees offreedom 2m.Analysis39ofmeasurements onactualaircraft Hying straight, levelcoursesshowsthatthecross-section fluctuations ataparticular aspectarewell fittedbythechi-square distribution withtheparameter mrangingfrom0.9toapproximately 2 andwithaayvaryingapproximately 15dBfromminimum tomaximum. 
 W. G. Bath, M. 
 KM SWATH  
 15.4 presented a very difficult problem. Because ofuncertainty inmeasurements and intheoutcome ofcomponent development, there was nofirm assurance that itcould bemet. The success oftheundertaking, however, was not dependent onmeeting this coverage fully, since maximum range and altitude values within 20per cent ofthe values ofFig. 
 There are several other details that have not been included in Figure 4.21. As shown  in Figure 4.6, a portion of the first valid receive range gate (and possibly a portion  of the last range gate in the IPP) is typically blanked to avoid receiving transients of  the transmit-to-receive (and receive-to-transmit) switching. Also, if pulse compres - sion modulation is used on the transmit pulse, the range gate duration will be reduced  to match the transmit pulse bandwidth. 
 BASED SYSTEM ARE DIRECTLY  RELATED TO ITS HEIGHT ABOVE THE %ARTHS SURFACE &OR AIRBORNE SYSTEMS  THE EFFECTS OF A SUPERREFRACTIVE LAYER DEPEND UPON THE POSITION OF THE TRANSMITT ER AND RECEIVER RELATIVE  TO THE LAYER "OTH OF THESE FACTORS ARE RELATED TO THE ELECTROMAGNETIC WAVES ANGLE OF LAYER PENETRATION 4HE STEEPER THE PENETRATION ANGLE  THE LESS OF AN EFFECT THE LAYER WILL HAVE UPON PROPAGATION 4RAPPING 4RAPPING IS AN EXTENSION OF SUPERREFRACTION BECAUSE THE METEOROLOGICAL  CONDITIONS FOR BOTH ARE THE SAME 3HOULD THE REFRACTIVITY GRADIENT DECREASE BEYOND THE CRITICAL GRADIENT  THE RADIUS OF CURVATURE FOR THE WAVE WILL BECOME SMALLER THAN THE %ARTHS CURVATURE 4HE WAVE WILL EITHER STRIKE THE %ARTH AND UNDERGO SURFACE REFLECTION  OR ENTER A REGION OF STANDARD REFRACTION AND BE REFRACTED BACK UPWARD  ONLY TO REENTER THE AREA OF REFRACTIVITY GRADIENT THAT CAUSES DOWNWARD REFRACTION 4HIS REFRACTIVE CONDITION IS CALLED TRAPPING BECAUSE THE WAVE IS CONFINED TO A NARROW REGION OF THE TROPOSPHERE 4HE COMMON TERM FOR THIS CONFINEMENT REGION IS A  TROPOSPHERIC DUCT OR A  TROPOSPHERIC WAVEGUIDE )T  SHOULD BE NOTED THAT A TROPOSPHERIC WAVEGUIDE IS NOT A WAVEGUIDE IN THE TRUE SENSE OF THE WORD BECAUSE THERE ARE NO RIGID WALLS THAT PREVENT THE ESCAPE OF ENERGY FROM THE GUIDE 4HE REFRACTIVITY GRADIENTS AND THEIR ASSOCIATED REFRACTIVE CONDITIONS ARE SUMMA 
 To properly  take into account the pulse-train modulation caused by the beam shape, the computations  of the probability of detection (as given in Secs. 2.5.2.6, and 2.8) would have to be performed  assuming a modulated train of pulses rather than constant-amplitude pulses. Some authors do  indeed take account of the beam shape in this manner when computing the probability of  detection. 
 N. Davies: Wide Band.width Butler Matrix, Eircrrot~ics Lrrrers, vol. 3,  pp. 
 The pattern produced in this manner may not hc as  accurate as might be produced by a well-designed array antenna, but operationally, it is riot  necessary to approximate the cosecant-squared pattern very precisely. A common method of  producing the cosecant-squared pattern is shown in Fig. 7.24. 
 VARYING  FROM  AN /4(2 PERSPECTIVE  IT IS USEFUL TO SEPARATE THE hFASTv PROCESSES OR hDYNAMICSv FROM THE hSLOWv OR hSTRUCTURALv VARIABILITY ! PHENOMENON IS TERMED  DYNAMICAL RELATIVE TO  A RADAR OBSERVATION PROCESS IF IT OCCURS ON A TIMESCALE COMMENSURATE WITH THE CORRE 
 Turner, and   K. Sarabandi, “SIR-C data quality and calibration results,” IEEE Transactions on Geoscience   and Remote Sensing , vol. 33, pp. 
 Water-vapor gradients are more efkc-  tive than temperature gradients alone; thus superrefraction is usually more prominent over  oceans, especially in warm climates.  Ducting occurs when the upper air is exceptionally warm and dry in comparison with the  air at the surface. There are several meteorological conditions which may lead to the formation  of s~~perrefracting Over land, ducting is usually caused by radiatioaof heat from  the earth on clear nights, especially in the summer when the ground is moist. 
 The D1 dataset has a total of 2000 images for training, so the simple network can produce features pretty well, while when consider with D2 and D3 dataset, the simple network cannot give good expression. Therefore, they had lower accuracy. Furthermore, when using traditional CNN models, it may take more than 1000 epochs when the results become steady. 
 NOISE AMPLIFIER 'A!S --)# AND AN 8 BAND POWER AMPLIFIER 'A!S --)# ARE SHOWN IN &IGURE  AND &IGURE   RESPECTIVELY &)'52%   , 
 Daniell, L.D. Brown, D. N. 
 27. Trunk. (j. 
 That is,  a tangent plane is passed through the surface coordinate at the patch dS, and the total  surface fields are taken to be precisely those that would have existed had the surface  at dS been infinite and perfectly flat. In essence, we do not know these fields, but we  take our best guess as to what they are and insert that estimate into either of the two  integrals. That done, the estimate of the unknown fields in the integrals of Eqs. 
 Therefore, after the bottomside electron density proﬁle of ionosphere has been precisely measured by an ionosonde, the corresponding PolSAR TEC can be used to calculate the TEC To pfor the ionosonde. Resorting to Equation (9), we can derive the parameter HT. Then, the topside proﬁle could be easily calculated from Equation (3). 
 1, 1980. 27. GE-592 Solid State Radar Systems, brochure, General Electric Company. 
 17. flcan. U. 
 48-50.  Hh. Shelton, J. 
 Problems are not included in this book. Although the author  assigns problems when using this book as a text, they are not considered a major learning  technique. Instead, the comprehensive term paper, usually involving a radar design problem or  a study in depth of some particular radar technology, has been found to be a better means for  having the student reinforce what is covered in class and in the text. 
 If the transmitted waveform is  a train of rectangular pulses of width 1 and pulse-repetition period TP = ljf P, the average  power is related to the peak power by  (2.43)  The ratio Pav/ P,, r/Tp, or rf11 is called the duty cycle of the radar. A pulse radar for detection of  aircraft might have typically a duty cycle of 0.001, while a CW radar which transmits contin­ uously has a duty cycle of unity.  Writing the radar equation in terms of the average power rather than the peak power, we  get  R4 _ Pa.,GAeanEi(n)  mu -(4n)2kTo Fn(Bn r)(S/N)i fp (2.44u)  The bandwidth and the pulse width are grouped together since the product of the two is  usually of the order of unity in most pulse-radar applications. 
 MING  )N GENERAL  FOR THE TRANSFORMATION AND DEGREES OF FREEDOM REDUCTION TO BE USEFUL  THE RESULTANT DEGREES OF FREEDOM MUST BE GREATER THAN THE INTERFERENCE RANK 0RE 
 This effect is averaged  out except for the noise spectral energy near the scan rate. For example, a periodic  modulation spike near the scan rate will cause the tracking radar to drive its antenna  in a circular motion around the target at a rate equal to the difference in frequency  between the scan rate and the frequency of the spectral line. The direction, clockwise  or counterclockwise, depends upon whether the spectral line is above or below the  scan rate and whether the scan is clockwise or counterclockwise. 
 PHASE AND QUADRATURE OUTPUTS FROM THE !$ CONVERTER ARE STORED IN A 02) MEMORY AND ALSO SUBTRACTED FROM THE OUTPUT FROM THE PREVIOUS TRANS 
 D. Burnside, and J. S. 
 LOADING TECHNIQUES  ARE EMPLOYED IN WHICH CASE BANDWIDTH IS INCREASED AT THE EXPENSE OF RADIATION EFFI 
 25-28, 1977.  63. Sinclair, G.: Theory of Models of Electromagnetic Systems, Proc. 
 STATE INFORMATION  INCLUDING SIGNIFICANT WAVE HEIGHT AND PERIOD  DIRECTION  AND SPEED  4HE -IROS !3 7AVEX4- SYSTEM DETERMINES DIRECTIONAL  WAVE SPECTRA SCALED IN M(Z AND PARAMETERS SUCH AS SIGNIFICANT WAVE HEIGHT AND  AVERAGE WAVE PERIOD !N &&4 IS PERFORMED ON DATA COLLECTED ON A SCAN 
 1957.  65. Rinehart, R. 
 The Kelvin rheological model, a typical one-dimensional linear rheological model, is adopted to form a functional relationship between radar line-of-sight deformation and the rheological parameters (elastic modulus and viscosity). The method of rheological parameter estimation is also illustrated in this paper. The proposed model is tested by a simulated experiment and a real data experiment. 
 DOPPLER CLUTTER 4HEY HAVE BEEN KNOWN TO IMPACT SKYWAVE RADAR SYSTEMS SEVERELY )ONOSPHERIC 6ARIABILITY  7HILE ALL IONOSPHERIC PROPERTIES ARE TIME 
 LOBE PATTERNS 0ASSIVE COMBINER NETWORKS ARE USED TO GENERATE MULTIPLE RECEIVE BEAMS STACKED IN ELEVATION AND A SINGLE TRANSMIT BEAM 4HE RECEIVE BEAMS REQUIRE LOW AZI 
 DIMENSIONAL GRAPHS &OR THE FIRST  GRAPH  CALLED COPOLARIZED  ONE USES THE COMPONENTS OF THE RECEIVED SIGNAL THAT ARE  THE  SAME AS THE TRANSMITTED 
 VELOCITY COMPONENT ALONG THE ANTENNA CENTERLINE BORESIGHT  AND IS GIVEN AS n6 G COS @   )F THE CLUTTER SURFACE WERE COPLANAR WITH THE AIRCRAFT  THIS COMPONENT  WOULD BE EQUAL TO  
 38.Lain.C.M.,andE.J.Gersten: AN/TPS-59 System,IEEE1975International RadarConf.,April21-23, 1975.pp.527-532,IEEEPuhlication 75CHO938-1AES. 39.Gerard, W.A.:Frequency-Agile Coaxial Magnetrons, Microwave i.,vol.16,pp.29-33,March, 1973. 40.Day,W.R..Jr..andT.H.Luchsinger: NewDevelopments inElectrostatically Focused Klystrons, MicrowQ('(' i..vol.13,pp.5963,April.1970.. 
 The circuit is quite  impossible.” On being told that no sport with his feel-  ings was intended, and that the circuit was, in fact, an  accurate delineation of a piece of commercial radar  equipment, he remained puzzled and suspicious, and  kept repeating, ‘‘But it couldn’t work. The circuit is  impossible.”  Perhaps this is an extreme case, but nevertheless it is  borne out by instructors who have to prepare radar  mechanics and service engineers to handle civil and  military radar. These instructors find that newcomers  to the techniques of radio are prepared to take the ad-  mittedly strange radar circuits at their face-value, and  will reason out for themselves the manner of the circuit’s  functioning. 
 Antenna gain is directly proportional to aperture. An isotropic  antenna has an aperture of λ² / 4π . An antenna with a gain of G has an aperture of G • λ² / 4π . 
 TION DATA v )%%% 4RANS VOL !%3  P     0 +ALATA  h4HE TRACKING INDEX ! GENERALIZED PARAMETER FOR  @  
 (This assumes the lowest frequency is determined by the condition that the  element spacing be not less than one-half wavelength.) With d = 0.6,l0, the beam can be  scanned from -48° to + 36° without the appearance of grating lobes, for l/d = 15. 1 IIE FUTTRONICALLY SlEERElJ PHASED ARRAY ANTENNA IN RADAR 301  It is possible for a frequency-scan array lo employ different frequencies lo radiate over the  same angular region, assuming that the antenna.feed· and.· elements are sufficiently  broadband. 64 This can be seen from an examination of Eq. 
 58, pp. 1164-1181, 1977. 66. 
 The 1-m SpotSAR resolution  constrains the design, one consequence of which is the symmetrical body-mounted  3-m diameter umbrella-style mesh reflector (0.5 kg) driven by one of ten feed horns  slightly offset from the focal point. This unity-aspect ratio antenna is a notable depar - ture from the rectangular antennas so typical of most space-based SAR precedents.  ch18.indd   12 12/19/07   5:13:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
  AND THREE 
 A block diagram of a guard channel mechanization is shown in Fig. 17.8. After the CFAR circuits (which ideally would be identical in both channels), there are three thresholds: the main channel, guard channel, and main-to-guard-ratio threshold. 
 Conv. Record.)  112INTRODUCTION TORADAR SYSTEMS 2.0,--,-----.---.-----,---,--,----,----,----,-----, (1) LJ.. :I: I \1)1.2 VIco0­ VI \1)... 
 VEILLANCE  IF CONCERNED WITH SHIP TRAFFIC  CAN AFFORD TO RELAX THE REVISIT TIME TO TENS OF MINUTES AS SHIPS MOVE SO SLOWLY  BUT IN ORDER TO ACHIEVE DETECTION  LONG #)4S OF n S ARE REQUIRED TO SEPARATE THE SHIP ECHOES FROM THE SEA CLUTTER IN THE DOPPLER SPECTRUM %VEN SO  THE RADAR CAN STEP ACROSS THE BARRIER ARC  WITH PLENTY OF TIME TO INTERLEAVE A 4ASK  DWELL BETWEEN ADDRESSING SUCCESSIVE $)2S IN 4ASK  )F THE BARRIER 4ASK  WERE CONCERNED WITH AIRCRAFT  WITH A #)4 OF n S  THE REVISITS WOULD NEED TO BE FREQUENT ENOUGH TO ACHIEVE THE DESIRED PROBABILITY OF DETECTION BEFORE THE AIRCRAFT HAD TIME TO CROSS THE BARRIER /NE APPROACH IS TO WIDEN THE BARRIER BY PROCESSING MORE RANGE CELLS OR BY REDUCING THE WAVEFORM BANDWIDTH AND ALLOWING THE RANGE CELLS TO GROW WIDER  BUT THIS MAY FAIL IF THE IONOSPHERE DOES NOT SUPPORT PROPAGATION OVER THE INCREASED RANGE DEPTH !NOTHER POSSIBILITY IS TO INCREASE THE REVISIT INTERVAL OVER A SUBSET OF THE $)2S 4HE RELATIVE PRIORITY OF 4ASKS  AND  WOULD ALSO NEED TO BE TAKEN INTO ACCOUNT 4ASK  BALLISTIC MISSILE LAUNCH DETECTION  WOULD REQUIRE MUCH MORE FREQUENT SUR 
 SUREMENTS OF LASER RADIATION HAVE BEEN MADE AT "ELL 4ELEPHONE ,ABORATORIES  AND  # 
 I_17 resolution, 17.5 to 17.10 resolution (crossrange) examples, 17.5 to 17.6 shadows in, 17.28 signal-to-noise ratio, 17.16 to 17.17 slow-time processing, 17.6 for space applications, 18.5 to 18.29 specific aspects of, 17.22 to 17.34 spotlight, 17.4 to 17.5 squinted stripmap, 17.4 stereo, 17.29 to 17.30 stripmap, 17.3 to 17.4, 17.14 to 17.15 types of, 17.2 to 17.6 vibrating targets in, 17.25 to 17.27 unfocused, 17.3 Washington monument image, 17.18 to 17.21 System instabilities and MTI, 2.65 to 2.73 System noise, 6.5 T TACCAR, 3.4 to 3.9, 3.33 Target acquisition, in tracking radar, 9.20 to 9.21 Target caused errors in tracking, 9.26 to 9.37 Target cross section. See radar cross section Target noise, in tracking radar, 9.26 to 9.37 T arget recognition, 1.7 cooperative, 5.22 to 5.23 noncooperative 5.22 to 5.24 Target resolution, in automatic detection, 7.19 to 7.20 Taylor weighting or illumination, 8. 7 to 8.9, 13.29 TecSAR, 18.12 TEM horn, 21.27 to 21.30 Terminal Doppler Weather Radar (TDWR), 19.1, 19.30 to 19.31 MTI filter design for, 2.47 to 2.50 Terrain avoidance, 5.28 to 5.29 Terrain-bounce jamming, 24. 
 80. Kurtz. L. 
 Gray, Y . I. Abramovich, and S. 
 TAL EFFECTS AGAINST CLUTTER WHEN DOPPLER PROCESSING IS USED ! LOG RECEIVER IS A DEVICE WHOSE VIDEO OUTPUT IS PROPORTIONAL TO THE LOGARITHM OF THE ENVELOPE OF THE 2& INPUT SIGNAL OVER A SPECIFIED RANGE )T MIGHT BE USEFUL IN PREVENTING RECEIVER SATURATION IN .   %,%#42/.)# #/5.4%2 
 IEEE Geosci. Remote Sens. Lett. 
 ORDER DOPPLER  SPECTRUM CHARACTERISTICS v .AVAL 2ES ,AB 2EPT   -AY     2 / 0ILON AND * - (EADRICK  h%STIMATING THE SCATTERING COEFFICIENT OF THE OCEAN SURFACE FOR  HIGH 
 1976.  80. Hitney, kl. 
 2of this series.. SEC. 317] NA VIGA TIO.V 109 Airborne radar isbest used asasupplement tostandard navigational methods, rather than asasubstitute forthem. 
 A second correlator, the B correlator, resolves the range  ambiguities out to the same range, but before a target can enter the B correlator,  its amplitude is thresholded by a range-varying threshold (the STC threshold).  A range gate by range gate comparison is made of the correlations in the A and B  correlators, and if a range gate correlates in A and not in B, that gate is blanked  out of the third correlator, the C correlator. The C correlator resolves the range  ambiguities within the maximum range of interest. 
 McGraw-  tiill Book Company. New York. 1970. 
 SAW technology has expanded because of the invention of the interdigital transducer,3 which provides efficient transformation of an electrical signal into acoustic energy and vice versa. In spite of these advanced technologies, the most commonly used pulse compression waveforms are still the linear-FM and the phase-coded signals. Improved tech- niques have enhanced the processing of these "old standby" waveforms. 
 The limitation to the improvement factor due to antenna rotation, or scanning modula-  tion, can be reduced 'by a method,similar to DPCA.51.58166 DPCA applies the difference  pattern in quadrature (900 phase shift) to thesum pattern while compensation for scanning  modulation requires the difference pattern to be applied in phase with the sum pattern. Thus it  144INTRODUCTION TORADAR SYSTEMS twoseparate antennas withthedistance between themequaltoTpVx=TpvsinOa,where Oa=anglebetween velocity vectorofthevehicleandtheantenna beam-pointing direction, andTp=pulserepetition period.Onepulseistransmitted ontheforward antenna, andthe otherpulseistransmitted ontherearantenna sothatthetwopulsesfromthetwodifferent antennas aretransmitted andreceived atthesamepointinspace.Theresultisasifthe radarantenna werestationary. Thedistance traveled between pulsesisgenerally lessthan theantenna dimension sothatthetwoantenna beamsmightbegenerated withtwo overlapping reflector antennas orwithaphasedarraydivided intotwooverlapping subarrays.64 Theeffective separation between theantennas, TpVx'varieswiththeangle 8aaswellastheaircraftvelocity v.Withreflector antennas, itisnotconvenient tochange theantenna physical separation tocompensate forchanges inOaorv.Thepulserepetition periodTpmightbevariedtoprovidecompensation, butthiscanintroduce othercomplica­ tionsintotheradardesignandthesignalprocessing. 
 SeveralfactorstendtospreadtheCWsignalenergyoverafinitefrequency band.These mustbeknownifanapproximation tothebandwidth required forthenarrowband doppler filteristobeobtained. Ifthereceived waveform wereasinewaveofinfiniteduration, itsfrequency spectrum wouldbeadeltafunction (Fig.3.5a)andthereceiverbandwidth wouldbeinfinitesimal. Buta sinewaveofinfiniteduration andaninfinitesimal bandwidth cannotoccurinnature.The morenormalsituation isanechosignalwhichisasinewaveoffiniteratherthaninfinite duration. 
 I. Skolnik (ed.), McGraw-Hill  Book Company. New York. 
 The purpose of an SLB system is to prevent  the detection of strong targets and interference pulses (as they might appear after  pulse compression) entering the radar receiver via the antenna sidelobes. Thus, SLB  is mainly used to eliminate interference from other pulse transmissions and deliber - ate pulse-like jamming. Also, SLB is effective against coherent repeater interference  (CRI); here “coherent” means that the interference tries to mimic the coded waveform  radiated by the radar appearing as a spike signal after pulse compression.42–45,34 A  method of achieving this is to employ an auxiliary antenna coupled to a parallel receiv - ing channel so that two signals from a single source are available for comparison. 
 WAVE TUBES IS TYPICALLY A FRACTION OF A WAVELENGTH 4HEY BECOME SMALLER AS THE FREQUENCY IS INCREASED WAVELENGTH IS DECREASED  3MALLER SIZE MEANS THAT A TUBE CANNOT DISSIPATE HEAT AS WELL AS A LARGER TUBE  SO THAT THE POWER CAPABILITY OF MICROWAVE POWER TUBES DECREASES APPROXIMATELY INVERSELY AS THE SQUARE OF THE FREQUENCY 4HE GYROTRON  ON THE OTHER HAND  DOES NOT HAVE THIS TYPE OF FREQUENCY DEPENDENCE SINCE IT USES WHAT IS CALLED A  FAST 
 Bythis term is meant the addition totheradar signals ofsignals which, byappropriate intensity-modulation ofthe indicator, reproduce onthe display itself a map, agrid, orany pattern that may bedesired. The position ofradar echo signals can becompared with this electronic map with complete freedom from parallax, and, inaddition, any distortions orimperfections ofthedisplay affect thegrid and thesignals equally and thus produce no reading error. Avery satisfactory method ofaccomplishing this has been given thename of“video mapping. 
 232 INTRODUCTION TO RADAR SYSTEMS  The normalized radiation pattern is  where +b = n(a/il) sin 4. In Fig. 7.3 the gains of both patterns are normalized. 
 BAND NOISE IS THEN REJECTED THROUGH SUBSEQUENT DIGITAL SIGNAL PROCESSING 4HE RESULTING 3.2 OF THE SYSTEM AFTER DIGITAL FILTERING WITH RECEIVER BANDWIDTH  " 2  AND SAMPLE RATE FS IS GIVEN BY  3.2 D" 3.2 D"F "3 2393 !$#    L O G  ¤ ¦¥³ µ´ 
 If the detection does not  contain doppler information, the new detection is usually used as the predicted  position (in some military systems, one assumes a radially inbound velocity), and  a large correlation region must be used for the next observation. The correlation  region must be large enough to capture the next detection of the target, assuming  that it could have the maximum velocity of interest. A common track initiation FIGURE 7.35  The applicability of different detection-to-track association algorithms  is determined by the density of false alarms and the dimensionless tracking parameter  gtrack. 
 IIIC in the Sunderland achieved 20 –30% better detection range than ASV Mk. III in the Wellington against a submarine beam-on and 50 – 100% better performance against a submarine end-on. This improved performance was reported in [ 11] without further comment. 
 13.11).44.45 In general, neither the Rayleigh nor the log-normal pdf's  accurately describe the statistics of real clutter, which usually lies between the two. The  Weibull pdf (Eq. 13.12), which is intermediate between the Rayleigh and the log normal, has  been suggested as applicable to land clutter. 
 SHAPED DISTRIBU 
 POSITIONING COMPUTER ON AN ELECTRONIC 
 G. R., and M. B. 
 ING SYSTEM  2ADAR ANTENNA GIMBAL DESIGNS VARY GREATLY DEPENDING UPON SCAN RATE  &/6  TRACKING REQUIREMENTS  ANTENNA SIZE  MASS  ETC "ASIC &EEDS   &OR RADARS REQUIRING A SIMPLE PENCIL BEAM  BASIC SINGLE MODE  WAVEGUIDE HORN FEEDS SUCH AS PYRAMIDAL 4% MODE  AND CONICAL 4% MODE  HORNS ARE  WIDELY USED 3INGLE 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 The term quasi-monostatic is used to denote configurations in which the transmit and  receive sites are separated, as is often done with radars employing FM-CW wave - forms, but not so far apart that the angle subtended at the target is more than ~5 °, so  the scattering behavior is close to what is observed for exactly monostatic geometry . 
 One-dimensional Deflection-modulated Display s.—Since one- dimensional displays yield little geometrical information, their only justification isthat they permit the use ofdeflection modulation, which gives amaximum ofinformation about the intensity and form ofthe echo signals. For this purpose, itisbest todisplay the signals asa function oftime orrange, and thus the only displays using deflection modulation arethose inwhich the deflections areapplied perpendicular toarange sweep (Fig. 6“1). 
 BEAM CLUTTER DISCRIMINANTS ONLY AND ARE OTHERWISE DISCARDED 4HE BINS   IN THE EXAMPLE  IN EACH GRID CELL ARE ENSEMBLE AVERAGED %!  IN SUM AND  DIFFERENCE CHANNELS 4HE POWER IN EACH BIN IN A GRID CELL IN THE CLEAR THERMAL NOISE LIMITED  REGION IS COMPARED TO A THRESHOLD  0 4(%!   WHICH IS A FUNCTION OF THE %!  IN THAT GRID CELL )N THE ENDOCLUTTER NEAR SIDELOBE REGION  A DISCRIMINANT   #S  IS FORMED  AND USED TO PROVIDE ADDITIONAL CLUTTER CANCELLATION PRIOR TO THRESHOLDING !GAIN  THE THRESHOLD  0 4(%!   IS A FUNCTION OF THE %! IN THAT GRID CELL AND A PRIORI KNOWLEDGE OF  THE CLUTTER STATISTICS !LTHOUGH ONLY ONE THRESHOLD IS DESCRIBED  TWO ARE ACTUALLY USED BEFORE HITS AND THEIR CORRESPONDING DISCRIMINANTS ARE PASSED TO THE TRACK FILES !LL LOW THRESHOLD HITS ARE PASSED TO ACTIVITY COUNTERS !S COMPLEX AS THIS THRESHOLDING SCHEME SEEMS TO BE  IT IS VERY DETECTION POWER EFFICIENT 4YPICAL '-4 7EAPON $ELIVERY  !S MENTIONED PREVIOUSLY  MISSILE GUIDANCE  REQUIRES TRACKING OF BOTH TARGETS AND MISSILES ALSO BULLETS IN GUN LAYING RADAR  GUN LAY 
 STATE MODULES AS  PART OF THE TRANSMITTER  ITSELF  SO THAT TIME TO REPAIR WAS REDUCED !N EXAMPLE OF THE SECOND APPROACH TO ACHIEVING A SOLID 
 An example of  an .Y-barid rrietal-plate zoned leris is shown in Fig. 7.20.  Atlottier class of rr~etal-plate lerls is the constrained lens, or path-length lens, in which the  rays are guided or constrairled by the metal plates. 
 ~-angle tracking.41 53•90-94 A radar that tracks a target at a low elevation angle, near the  surface of the earth, can receive two echo signals from the target, Fig. 5.15. One signal is  retkcted directly from the target, and the other arrives via the earth's surface. 
 Hoogasian, “Exact ray calculations in a quasi-parabolic ionosphere with no  Magnetic Field,” Radio Science , vol. 3, pp. 69–74, 1968. 
 In spite of these  limitations, the HF region of the spectrum is of special interest for radar because of its unique  property of allowing propagation to long distances beyond the curvature of the earth by  means of refraction from the ionosphere. A single refraction allows radar ranges to be ex­ tended to almost 4000 km. The targets of interest to HF over-the-horizon (0TH) radar are the . 
 With pulse radar we can  choose suitable transmitting frequencies and introduce  other methods, so that scatter from the ionosphere and  reflections from near-by objects can be ignored.  It is possible to suppress PE’s to a certain extent on  the pulse system, so for some navigational purposes  ranging and direction-finding by pulse radar are to be  preferred.  In summing up the relative advantages of radar  systems a Ministry of Aircraft Production Telecom-  munications official has pointed out:  We have to remember that there are essential differences  between war and peace transport needs. 
 PRIATE FOR A TACTICAL RADAR OPERATOR  IE  A HEIGHT VERSUS RANGE DISPLAY OF RADAR PROBABILITY OF DETECTION AS A PERCENTAGE  AS ILLUSTRATED IN &IGURE  4HIS DISPLAY IS REFERRED TO AS A TACTICAL DECISION AID BECAUSE IT WILL ALLOW THE RADAR OPERATOR TO MAKE SOME SORT OF TACTICAL DECISION &OR EXAMPLE  SUPERIMPOSED ON THIS TACTICAL DECISION AID IS THE FLIGHT PROFILE OF A TARGET MISSILE THE SOLID LINE SLOPING DOWNWARD TO THE ORIGIN FROM RIGHT TO LEFT  4HE ATMOSPHERIC ENVIRONMENT IS SURFACE 
 The sum signal has higher sidelobes because the separation between  the phase centers of the separate antennas is large. (These high sidelobes are the result of  qratinq lohes. similar to those produced in phased arrays.) The problem of high sidelobes can  he reduced hy overlapping the antenna apertures. 
   '2/5.$ %#(/  £È°Î BETWEEN GROUND AREA AND PROJECTED AREA 4HE GROUND AREA IS PROPORTIONAL TO  $Q  AND  THE PROJECTED AREA IS SMALLER 4HUS  OR SG G Q SG Q !D D !     C OS COSPROJECTEDAREA      3INCE BOTH  F  AND R  ARE CALLED SCATTERING COEFFICIENTS  READERS OF THE LITERATURE MUST BE  ESPECIALLY CAREFUL TO DETERMINE WHICH IS BEING USED BY A PARTICULAR AUTHOR 2ADAR ASTRONOMERS USE A DIFFERENT R  TOTALRETURNPOWERFROMENTIRESURFACE POWERRETURN NEDFROMPERFECTISOTROPICSPHEREOFSAMERADIUS    4HE  RESULTING VALUE FOR  R  IS USUALLY MUCH SMALLER THAN  R  FOR THE PLANET AT VERTICAL  INCIDENCE AND IS LARGER THAN THE VALUES OF  R  NEAR GRAZING INCIDENCE RETURN FROM THE  LIMB OF THE PLANET  2ELATIVE )MPORTANCE OF 4HEORY AND %MPIRICISM  4HE THEORY OF RADAR GROUND  RETURN HAS BEEN THE SUBJECT OF MANY PUBLICATIONS  4HE VARIOUS THEORIES  INSOFAR AS  THEY CAN BE CONFIRMED BY EXPERIMENT  PROVIDE BASES FOR JUDGING  THE EFFECTS OF VARIA 
 Pulsar Emissions, Signal Modeling and Passive ISAR Imaging. Sensors 2019 ,19, 3344. [ CrossRef ] [PubMed ] 8. 
 EYE  USED AGAINST MONOPULSE  RADARS GENER 
 Rept. 21. Verlag Leemann, Zurich, 1955. 
 The detection signal characteristics (such as amplitude or signal-to-noise) are  then re-thresholded to reduce sensitivity in regions of unacceptably high activity. In  no circumstances are detections eliminated if they fall within a track gate (i.e., a gate  centered on the predicted position of a firm track). Figure 7.26 illustrates an example  FIGURE 7.26 Histogram of detection signal-to noise ratio detection  illustrating the effectiveness of the activity control using the signal-to-noise  test in rain clutter. 
 177. Sensors 2018 ,18, 3750 Figure 19. InISAR imaging results of anechoic chamber target with complete data. 
 H., and W. A. Skillman: Pulse-doppler Radar, chap. 
 RADAR TRANSMITTERS 211  drive-pulse by mounting an electrode in the cathode, but insulated from it, in the region of the  drift space between the RF input and output ports. This is known as a cutoff, or co11trol,  electrode. A positive potential is applied to this cutoff electrode at the termination of the pulse  to collect, or q11e11clr, the remaining electron current. 
 Unlike conventional  microwave radar, the specific frequency to be used by an 0TH radar is a function of the range  that is desired and the character of the. ionosphere. Since the ionosphere varies with time of  day, season, and solar activity, the optimum radar frequency will vary widely. 
 The total rms phase error is 5.7 °. It  should be noted that there are numerous sources of phase and amplitude errors that  are induced by the phase shifters, the feed network, the radiating elements, and the  mechanical structure. The task of building a low-sidelobe antenna is one of reducing  each of the amplitude errors to a few tenths of a decibel and the phase errors to a few  degrees. 
 The use of the classical maximum  likelihood solution for the optimum double-null difference pattern results in relatively large  sidelobes at the horizon and at angles below the image. By slightly sacrificing the accuracy of  angle tracking (due to less slope sensitivity), lower sidelobes can be achieved. Such a pattern  which sacrifices slope sensitivity for lower sidelobes has been called a tempered double-null  ditference pattern.48  The tempered double-null is more suited to mechanically steered trackers than to ehased­ a~~since it is basically a null balance technique that does not achieve full accuracy  until it goes through a settling process. 
 47. Harvey, A. F.: Optical Techniques at Microwave Frequencies. 
 The spurious signal magnitudes are  less predictable as the magnitudes of the dominant spurious signals are a function of  the D/A converter nonlinearity. When generating CW waveforms, the D/A converter sequence repeats after 2K  samples where 2K equals the greatest common divisor of 2Nf and Mf . Thus, spurious  signals occur only at frequencies:   fnf K spurclk=2, n = 0,1,2,... 
 Figure 7.29  shows a bank of multiple parallel filters all fed by the same stream of associated mea - surements. At each detection time, tk, one of the several filter outputs must be selected  to be the track state used for detection to track association. A systematic way of employing multiple target motion models is the Interacting  Multiple Model (IMM) approach diagrammed in Figure 7.30.56 Multiple models run  simultaneously; however, they do not run independently. 
 ATES . COMPLEX NUMBERS AS OUTPUT  WHERE THE OUTPUT SAMPLES REPRESENT  THE FREQUENCY  CONTENT OF THE INPUT DATA SEQUENCE &OR A SAMPLE RATE  F S  EACH OUTPUT FREQUENCY SAMPLE  BIN  HAS A WIDTH OF  FS. 4HE MTH OUTPUT SAMPLE   8M   REPRESENTS THE AMPLITUDE AND  PHASE OF THE FREQUENCY CONTENT OF THE FINITE 
 RELATION FUNCTION IS   20 J F## F D   E X P  E X P  TP ST P T 
 Often, power converters are operated at switching frequencies up to several hundred  megahertz to reduce the size of magnetics and filter components, and sometimes, the  switching frequencies are synchronized to the radar master clock. 5.2 TYPICAL MISSIONS AND MODES Air-to-Surface Mission Profile . The mode structure of any modern fighter air - craft arises from mission profiles.7,9 One typical mission profile for an air-to-surface  (A-S) strike is shown in Figure 5.10. 
 R. H. Abrams, B. 
 BASED REMOTE 
   -%4%/2/,/')#!, 2!$!2   £°Ó£ !N EFFICIENT MOMENT ESTIMATION TECHNIQUE WAS ORIGINALLY DESCRIBED BY 2UMMLER   AND REINTERPRETED BY $OVIAK AND :RNIC 4HIS ESTIMATOR MAKES USE  OF THE FACT THAT THE  COMPLEX AUTOCORRELATION FUNCTION OF THE RECEIVED SIGNAL HAS THE GENERAL FORM   2 N4 0 N4 JVN4R    E X P § ©¨¶ ¸·RP L    WHERE QN4   IS THE CORRELATION COEFFICIENT OF THE TIME SERIES DATA AND  N4 IS THE   TIME LAG )T CAN BE SHOWN THAT  V  THE MEAN VELOCITY  IS A FUNCTION OF THE FIRST LAG 24    V424  L PARG;   =    )T CAN ALSO BE SHOWN THAT   SL PV N 424 20 y 
 TYPE IMPLANT 4HE RESULTING SHORT CHANNEL CONTRIBUTES TO IMPROVED HIGH FREQUENCY RESPONSE IN SPITE OF THE LOWER MOBILITY OF SILICON 4HE MEASURED BREAKDOWN VOLTAGES CAN BE IN EXCESS OF  6  SO OPERATION AT HIGHER VOLTAGES IS POSSIBLE  OR CONVERSELY  A HIGHER LEVEL OF MARGIN IN RUGGEDNESS CAN BE ACHIEVED FOR A GIVEN OPERATING VOLTAGE THE LATTER IS A KEY ADVANTAGE FOR HIGH 
 H. Cooper, “Binary quantization of signal amplitudes: effect for radar angular accuracy,” IEEE  Trans ., vol. Ane-11, pp. 
 (Courtesy of Texas  J nst rnmcnts. Inc.)  User's requirements. Since the design or a radar is strongly influenced by the task it is to  accomplish, the radar designer should start with the user's requirements. 
 PULSE CANCELER !LSO SHOWN ARE THE VELOCITY RESPONSES OF A FIVE 
 58. W. Long and K. 
 The direction of reflection s can be written s = v - 2 (n • v) n (6.25) and the differential surface reflection at each grid region is modified by a pattern factor represented by a uniformly illuminated reflection steered in the direction of unit vector s and determined in the pattern direction unit vector p by 4irc/A sin irbx(sx - px) sin TrAy(sy - py)Pattern factor = — (6.26) \2\n - s\ TiAx(Sx - Px) TrAy(sy - py) This factor modifies the surface current / as seen in the far field, projected in the direction of interest. At a distant spherical surface, vector p is normal to the sur- face. Two vectors are determined at the surface for the polarizations of interest, both perpendicular to p and perpendicular to each other, considered main and cross-polarized directions. 
 It  is important if the electromagnetic spectrum, considered as a natural resource, is to be effec­ tively and efficiently utilized for the benefit of all. Military radars, however, must also operate  in a hostile environment where they may be subjected to deliberate interference designed to  degrade their performance. The various methods for interfering electronically with radar arc  cal led elect ro11ic cow1terme£Js11res, or ECM. 
 6. P. Renoult, E. 
 Another practical  advantage of subarray-level DBF is that less digital data, which must be processed to  form the receive beams, is produced than for element-level DBF. DBF can provide more efficient time-energy management than a single-beam ana - log beamforming array. Since DBF can produce multiple simultaneous beams, energy  can be traded off for improved search frame times as was discussed in Section 13.11. 
 TION OF EMISSIONS CONTROL TO MINIMIZE THE ABILITY OF THE ADVERSARY TO DETECT  TRACK  AND ATTACK USING THE RADAR EMISSION  7ITHOUT CARE  THESE EMISSIONS CAN EASILY SERVE AS A  STRONG GUIDANCE SIGNAL FOR A HOSTILE ANTIRADIATION MISSILE !2-   !NTENNA APERTURES  THAT HAVE MULTIPLE INDEPENDENT PHASE CENTERS CAN PERFORM BOTH ADAPTIVE CLUTTER CANCEL 
 1032–1047, June 2002. 24. S. 
 73, pp. 182-197, February 1985. 2. 
 3.45  DC Offset  ..........................................................  3.46  3.13 CFAR Detection Processes  ....................................  3.46  Application  ......................................................... 
 L. Stone, J.E. Clark, and W. 
 LOOK &INE    n  r   r      5LTRA 
 The spark gaps were VI507, having tungsten electrodes with 0.7 mm gap. The glass envelope was ﬁlled with argon at 600 mmHg, with 5 mg of mercury. A ceramic Figure 2.18. 
 5. D. Crombie, “Doppler spectrum of sea echo at 13.56 Mc/s,” Nature , vol. 
 Since Nrandom pulses arrive per second the number of triggering persecond will beNtimes this probability, or2TN2. Thus, theratio ofthenumber ofbeacon replies tothenumber ofrandom pulses persecond is2TN. If,forexample, T=5psec and N=500 pps, the product 2TN has avalue of~~, the number ofrandom triggerings per second being reduced from 500 to2.5. 
 The radar could scan in azimuth at a rate of 45° per second. It transmitted 2-fxs pulses with pulse repetition frequencies (PRFs) from 300 to 400 Hz, and operated with a peak power of 4.5 MW. *Nodding-antenna height finders have also been used for raid counting. 
 boresiglit (pointirig directioti), as well as cliange the VSWR and the antenna noise tempera-  ture. Sometimes in tracking radars, tlie rate of change of the boresight shift can be important.  (;cnerally, an antenna situated witliin a large ground-based radome sees the same approxi-  mate rado~ne envirorinierit rio rnattcr wlicre tlie beam points within its normal coverage. 
 ELEMENT ANTENNA AND TWO TIME SAMPLES  4HE TWO ANTENNAS ARE SEPARATED BY  D   V4 ;V   PLATFORM SPEED  4    PULSE REPETITION INTERVAL= ! 3!2 IMAGE  IS THEN FORMED BY CONVENTIONAL TECHNIQUES 4HE RESULT IS SHOWN IN &IGURE ; A=  4HE SMEARING OF THE MOVING POINTLIKE TARGET IS EVIDENT 'IVEN THE MOTION PARAM 
 A separate command  must be computed by the beam-steering computer and distributed to each phase shifter. The  power distribution to the columns is by parallel feed. The power in each column is shown  being distributed by a series feed to the vertical elements. 
 When aircraft passed through the beam, Hyland noted an increase in the  received signal. This stimulated a more deliberate investigation by the NRL personnel, but the  work continued at a slow pace, lacking official encouragement and funds from the govern-  nrent. although it was fully supported by the NRL administration. 
 DEFINED MAPS AS AN UNDERLAY TO THE RADAR IMAGE -ANY MAPS CAN BE CREATED AND STORED FOR FUTURE USE !LTHOUGH THIS FACILITY IS STILL WIDELY USED  THE USE OF VECTORIZED ELECTRONIC CHART DATA AS A RADAR UNDERLAY IS BECOMING MORE COMMON )N )-/ TERMS  THEY ARE KNOWN AS  CHART RADARS !LL APPROVED CHART RADARS HAVE TO BE CAPABLE OF DISPLAYING  OFFICIALLY RECOGNIZED VECTOR DATA 4HIS DATA IS KNOWN AS THE  %LECTRONIC .AVIGATIONAL  #HART %.#  )T IS ISSUED ON NATIONAL AUTHORITY AND COMPLIES WITH AN )NTERNATIONAL (YDROGRAPHIC /RGANIZATION  )(/  STANDARD KNOWN AS 3 %.# DATA IS NORMALLY  DISPLAYED ON APPROVED ELECTRONIC CHART SYSTEMS CALLED  %LECTRONIC #HART $ISPLAY AND  )NFORMATION 3YSTEMS %#$)3   AND MAY BE USED BY SHIPS IN PLACE OF PAPER CHARTS  %.# DATA IS KEPT UP 
 Mitzner, “Incremental length diffraction coefficients,” Northrop Corporation, Aircraft Div.  Tech. Rept. 
 .l'lle rrc1c.k-rrltrir~tertc~rtc~e function deterriiines when new observations should be nlade on  existing tracks in order to update the entries in the track file: Track maintenance not only  establishes when tile next radar observation must be made, but takes the steps necessary to  obtain it. In perforniing this function it is often convenient to obtain the target position  estiniate in radar coordinates. Radar errors can be readily handled in this coordinate system. 
 The same tapped delay line can be used as the  receiver matched filter by inserting the received echo at the opposite end (the right-hand side of the delay  line in this illustration). FXTRACTION OF INFORMATION AND WAVEFORM DESIGN 429  Table 11.2 Barker codes  Code length Code elements Side lobe level, dB  ----- 2 + ++  J + + ·- 4 + + +. 1 +-+ -6.0  9.5  -12.0  14.0  16.9  --20.8 <; I I I  7 I-' I  11 ! I +- LI ! I I I I I I-+-+ -22.3  is illustrated schematically a lapped delay line that generates this Barker-coded waveform  when an impulse is incident al the left-hand terminal. 
 A radar operates by radiating electromagnetic energy and detecting the echo returned from reflecting objects (targets). The na- ture of the echo signal provides information about the target. The range, or dis- tance, to the target is found from the time it takes for the radiated energy to travel to the target and back. 
 Theuseoftheword"uncer­ tainty"isamisnomer, forthereisnothing uncertain aboutthe"uncertainty" relation of Eq.(11.34).Itstatesthewell-known mathematical factthatanarrowwaveform yieldsawide. spectrum and a wide waveforrn yields a narrow spectrum and both the time waveform and the  frequency spectrum cannot be rnade arbitrarily small simultaneously.  The relation of Eq. 
 The synchronization pulses areamplified bya4-stage video amplifier oper- ating into apulse transformer connected tothecathode ofadiode through which ther-famplifiers draw their power. Intheabsence ofpulses, the diode isconducting and the plates ofthe r-famplifiers areconnected to the high-voltage supply (800 volts). The arrival ofapulse disconnects thediode and raises theplate potential oftheamplifier byseveral hundred volts, resulting inavery high instantaneous power. 
 A narrow, steerable beam in the elevation plane is desired for  0TH radar in order to avoid multipath propagation and to concentrate the energy at the  desired range. However, the large vertical. apertures to achieve such a capability are quite  costly, so that HF 0TH radars seldom have as large a vertical aperture, or as narrow an  elevation beamwidth, as might be desired. 
 • The use of the doppler filter bank and the clutter map in MTI radar. • The reduced dependency on operators for extracting information from a radar and the incorporation of CFAR in automatic detection and tracking systems. • The emergence of the analog SAW dispersive delay line as the preferred technique for wideband (high-resolution) pulse compression; the use of digital processing for the pulse compression filter when the bandwidth permits; and the introduction of Stretch pulse compression, which allows high resolution, over a limited range interval with considerably reduced processing bandwidth. 
 The general method may beexplained bythe block diagram of Fig. 511 and thegraphs ofFig. 512. 
 Figure 2.5shows the Yagi homing antennas on a Lockheed Hudson and ﬁgure 2.6shows the antenna installations on a Vickers Wellington. 2.2.2.3 Transmitters The transmitter T.3040 and variants, together with T.3069 (operating on 214 Mc/s), were similar in design. The power supply for the transmitter was housed in the samebox and fed from the 80 V AC supply from the aircraft generator and supplying a nominal 7.5 kV at 4 mA. 
 11.12. The heat generated inthemagnetron rises astheaverage power level isincreased, but the generation ofheat inthe receiver components is substantially constant from one radar settoanother. Ifthetransmitter power ismore than about 50kw, the thermal load forany pressurized. 
 Thisisduetotherelativel.Y.J~~ pulse~(sometimes onlyonepulse)p.e.rAream QOsiJip_n, aswellastheerrorintroduced bythe_.!<lrg~t echo aJ11pljtlld,~_,!~.!£!uations when ~...•---, ..-,. - sequential ratherthansimultaneous anglemeasurements aremade.Changes inechoampli- tudecauseerrorssincethesequential measurements arenccessarily madeatditTerent instants. OTHER RADAR TOPICS 545  of time. 
 Although a well-designed modern radar  can usually extract more information from the target signal than merely range, the measure-  ment of range is still one of radar's most important functions. There seem to be no other  competitive techniques which can measure range as well or as rapidly as can a radar.  The most common radar waveform is a train of narrow, rectangular-shape pulses modu-  lating a sinewave carrier. 
 Figure 9.2 shows a surface, which is illuminated by R a- dar from an altitude or height h at an angled incidence.  With pulse compression a region in  the range can be resolved, from here according to Equati on (9.3), as shown:     Figure 10.2  Illumination and region of resolution.   In order to achieve the azimuth resolution, as shown, θH must be decreased accor dingly. 
 392 INTRODUCTION TO RADAR SYSTEMS  the angular location of the target. The target can be found, as in beam splitting, by taking the  midpoint between the start and end of the threshold crossing. There will be a bias in the angle  estimate that depends on the signal-to-noise ratio, but this bias can be estin~ated acc~rately.~'  The standard deviation of angular estimates obtained with the single delay-line is about 15  percent greater than the optimum estimates based on the Cramer-Rao lower bot~nti.'~ If tire  maximum value of the output is used as an estimator of the target location, the bias is  constant. 
 Indeed, this information is so widespread that an adequate summary of the literature is impossible. Hence, this section can only give highlights of the results and major programs. The reader should consult the three major compendia of such data for more information both on results and on bibliography21-23'114 (note that information is spread through many chapters). 
 TIVE PHASES #ONSEQUENTLY  THE VECTOR SUM FLUCTUATES RANDOMLY  4YPICALLY  TARGET RAN 
 Thesimplelineararraywhichgenerates asinglebeamcanbeconverted toamultiple­ beamantenna byattaching additional phaseshifterstotheoutputofeachelement. Eachbeam tobeformedrequires oneadditional phaseshifter,asshowninFig,8.25.Thesimplearrayin thisfigureisshownwithbutthreeelements, eachwiththreesetsofphaseshifters.Onesetof phaseshiftersproduces abeamdirected broadside tothearray(0=0).Another setofthree phaseshiftersgenerates abeaminthe0=+00direction. Theangle00isdetermined bythe relationship 00=sin-1(1i¢)'/2rrd). 
 The radar design delivers high power output and beam/waveform agility in order to  support the long-range functional requirements of the THAAD mission. The THAAD  element components work in concert to detect, assign, and destroy incoming short- to  medium-range ballistic missiles by providing the firing battery with target acquisi - tion, interceptor support, and intercept assessment functions. These functions include  surveillance, THAAD missile track, in-flight data uplink/downlink, target classifica - tion/typing/identification, and intercept assessment. 
 Ifthe target isvery close tothe system, FIG, 5.8.—The upper figure shows thefrequencies present inthetrans- mitter spectrum. Thelower gives the same information for the receiver. Frequencies foandfo+/,inthereceiver areduetoleakage from thetransmitter; thesame frequencies ffDcomefrom the target.thenumber ofwavelengths from trans- mitter totarget and back will bethe same, even though thetwo transmitter wavelengths differ slightly. 
 Subsequently, geocoding in the line of sight (LOS) direction with a resolution of 10 m is employed to calculate SBAS. Finally, subsidence rate and subsidence time series are obtained and mapped across the study area. 3.5. 
 .. 14.7MILLIMETER WAVES ANDBEYOND Radarhasbeenapplied primarily inthemicrowave portionoftheelectromagnetic spectrum, withKgband(35GHz)representing thenominal upperlimitfortraditional radarapplica­ tions.Therehasbeencontinual interest, however, intheextension ofradartohigherfrequcn­ ciesinthemillimeter waveportion ofthespectrum. Figure 14.14illustrates the electromagnetic spectrum abovethemicrowave region,showing theplaceofmillimeter waves inrelationtotheinfrared andvisibleregions. 
 4HE RADAR RANGE EQUATION IS USED TO DETERMINE THE PERFORMANCE OF PULSE DOPPLER RADAR 4HE RADAR RANGE EQUATION MUST INCLUDE LOSSES  BOTH SYSTEM AND ENVIRONMENTAL  THAT WILL DEGRADE THE STRENGTH OF RETURN SIGNALS AT THE DETECTOR 0ROBABILITY OF DETECTION  0 D   DEPENDS ON TARGET SIGNAL 
 RGHPRF can provide all aspect detection but tail performance is dramatically poorer  due to sidelobe clutter. Even with STAP, which significantly improves sidelobe clutter  rejection, low altitude tail aspect detection for RGHPRF is poorer .44,45,55FIGURE 5.19  RGHPRF range-velocity blind zones, corresponding to Figure 5.18 waveforms FIGURE 5.20  High and medium PRF interleave for all aspect detection45 ch05.indd   21 12/17/07   1:26:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 v. Set the BRIGHTNESS, GAIN and CONTRAST controls: a. Switch on scanner motor and set gain and contrast fully anti- clockwise. 
 t$Ec. 9,18] DATA STABILIZATION 311 lettheantenna scan umi’ormly during search and tocontrol thedeflecting coil ofthe indicator tocorrect the deck-tilt error. This isaspecies of data stabilization; itisnot commonly used. 
 MT/ improvement factor. The signal-to-clutter ratio at the output of the MTI system divided  by the signal-to-clutter ratio at the input, averaged uniformly over all target radial veloci:  ties of interest.  Suhclutter visihility. 
 An example of a solid-state coherent radar is the Kelvin Hughes SharpEyeTM—the  first introduction of such an IMO-compliant system to the CMR market. It has a peak  output power of 170 W and a duty cycle of 10%. Figure 22.5 shows a photograph of  the transmitter electronics. 
 Following  the filter-bank, weighting is applied in the frequency domain to reduce the filter sidelobes.  Although unweighted filters with - 13.2-dB sidelobes might be satisfactory for most ground  clutter, the frequency spectrum of rain and other windblown clutter often requires lower  sidelobe levels. The magnitude operation forms (1' + Q')"'. 
 KO, H. C.: The Distribution ofcosmic Radio Background Radiation, Proc. IRE, vol. 
 POLARIZED SEA CLUTTER 4HESE RETURNS TENDED TO HAVE A WEAK DEPENDENCE ON GRAZING ANGLE AND WERE ALWAYS SMALLER THAN EITHER OF THE LIKE 
 DARD MONOSTATIC RADAR PROCESSING TECHNIQUES &)'52%   "ISTATIC ISODOPPLER CONTOURS FOR TWO DIMENSIONS AND A FLAT  EARTH #OURTESY ,EE 2 -OYER  4ECHNOLOGY 3ERVICE #ORP  .   ")34!4)# 2!$!2   ÓÎ°£Ç 2ESEARCH WAS STARTED IN THE S TO IMPROVE THE QUALITY OF BISTATIC 3!2 IMAGES   WHICH WERE CONSTRAINED TO COHERENT INTEGRATION TIMES OF A FEW SECONDS AND CONSE 
 The course on which this book is based is a proven method for introducing  the student to the subject of electronic systems. It integrates and applies the hasic concepts  found in the student's other courses and permits the inclusion of material important to  the practice of electrical engineering not usually found in the traditional curriculum.  Instructors of engineering courses like to use texts th~t contain a variety or problems that  can be assigned to students. 
 70, pp. 1174-1209, October 1982. 6. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 for target detection and estimation, realizability in hardware, susceptibility to interfer - ence, efficiency, and the electrical properties of the scatterers of interest. In addition: • HF radar waveforms must fit within available clear channels in the HF frequency  band, complying with stringent constraints on leakage into channels occupied by  other users. 
 Comment by V. G. Hansen, p. 
 The larger  along-track resolution reflects the 0.3-sec integration time of the returns. Antenna gain  is 63 dB. Average data rate is 15 kbits/s. 
 ONLY WEIGHTS AT EACH ELEMENT ARE SHOWN IN &IGURE  $ETERMINISTIC 2& NULLING USING AMPLITUDE AND PHASE CONTROL AT EACH ELEMENT PRO 
 On a conventional shipborne radar, an experienced operator can manually set the  detection threshold to give the best setting over any given area, but this is often only  effective over a small proportion of the total radar image. The use of automatic thresh - olding is able to give better detection over a complete scan but often cannot compete  with a skilled operator optimizing detection over a restricted area. In some conditions,  no existing radar gives the performance that a user ideally needs, despite the use of  50 ns pulses and sophisticated clutter processing technology. 
 In principle, a single antenna may be  employed since the necessary isolation between the transmitted and the received signals is  achieved via separation in frequency as a result of the doppler effect. In practice, it is not  possible to eliminate completely the transmitter leakage. However, transmitter leakage is not  always undesirable. 
 As the name implies, the  antenna element signals are first doppler filtered and then processed through STAP.  The motivation for this type of architecture is that the resultant STAP solutions can  independently address a subset of the clutter interference problem isolated to clutter  that remains in a single doppler filter. This technique may be more effective for radar  systems where the clutter environment and waveform selection lead to unambiguous  clutter returns within the radar’s PRF. 
 T able 3. The related parameters of ENVISAT-1 ASAR. Platform Polarization Band Boresight Incidence Angle Platform Height Platform V elocity ENVISAT-1 HH C 23.1◦800 km 7455 Figure 6. 
 Between the cylindrical cathode Cand anode block Aisaninteraction space Iinwhich thecon- version ofd-ctor-fpower takes place. Aconstant and nearly uniform magnetic field ismaintained inthis interaction space inadirection parallel tothe axis ofthe tube. Inoperation, the cathode ismaintained ata negative potential while the anode block isusually atground potential. 
 In addition to the changes in the shape of the main beam, the sidelobes also change in  a ppca ranee and posit ion.  Series l'S. parallel feeds. 
 2.13 DYNAMIC RANGE AND A/D CONVERSION  CONSIDERATIONS The accurate conversion of the radar IF signal into a digital representation of the  complex envelope is an important step in the implementation of a modern digital sig - nal processor. This analog-to-digital (A/D) conversion must preserve the linearity of  amplitude and phase over the required dynamic range, have a small effect on overall  radar system noise temperature, and be free from undesired spurious responses. Advances in A/D converter technology is now making it possible to directly con - vert an analog IF signal into a corresponding digital complex representation, rather  than going through the intermediate step of first downconverting the IF signal into  baseband in-phase (I) and quadrature (Q) components and subsequently using a sepa - rate A/D converter in each of these two channels. 
 M., and C. E. Antoniak: A Pnctical Distribution-Free Detection Procedure for Multiple­ Range-Bin Radars, IEEE Trans., vol. 
 The  kernel Γ k k1 2,( )  is discussed below. Eq. 20.6 reveals that the Barrick-Rice solu - tion has a simple interpretation in terms of spatial resonance or Bragg scattering. 
 #IRCUITS $EVICES 3YST  VOL   NO   PP n  *UNE   $ -ILLER AND - $RINKWINE  h(IGH VOLTAGE MICROWAVE DEVICES !N OVERVIEW v PRESENTED AT  )NTERNATIONAL #ONFERENCE ON #OMPOUND 3EMICONDUCTOR -FG    * :OLPER  h3CANNING THE SPECIAL ISSUE  SPECIAL ISSUE ON WIDE BANDGAP SEMICONDUCTOR DEVICES v  0ROCEEDINGS OF THE )%%%  VOL   NO   PP n  *UNE   5 -ISHRA  0 0ARIKH  AND 9 7U  h!L'A.'A. (%-4S!N OVERVIEW OF DEVICE OPERATION AND  APPLICATIONS v 0ROCEEDINGS OF THE )%%%  VOL   NO   PP n  *UNE   2 4REW  h3I# AND 'A. TRANSISTORS)S THERE ONE WINNER FOR MICROWAVE POWER APPLICATIONS v  0ROCEEDINGS OF THE )%%%  VOL   NO   PP n  *UNE   3 !LLEN  2 3ADLER  4 !LCORN  * 0ALMOUR  AND # #ARTER  h3ILICON CARBIDE -%3&%4S FOR HIGH  POWER 3 
 A. Cameron, “ The Jindalee operational radar network: its architecture and surveillance  capability,” Proc. IEEE Int. 
 Either the cookie cutter or the crown-of-thorns mechanisms can  achieve a 10 percent frequency change. The two can be used in combination to cover a larger  tuning range than is possible with either one alone.  A limited tuning range, of the order of 1 percent, can be obtained by a screw inserted in  the side of one of the resonator holes. 
 The angle in a clockwise direction from this reference axis is proportional to  the distance (in wavelengths) of the standing-wave-pattern minimum from the reference point.  An advantage of the Smith chart for plotting the effects of the load on the magnetron parameters  is that the shapes of the curves are practically independent of the position of the reference  point used for measuring the phase of the VSWR.  An example of a Rieke diagram for a coaxial magnetron is shown in Fig. 
 AES-9, pp. 649-653, September, 1973.  67. 
 For a large phased array type of radar operating in space, the thermal and natural radiation environments have significant influence on the design of an SBR. Particular effects depend on the orbital altitude and the materials used in the structure. THERMAL ENVIRONMENT EFFECTS. 
 9, pp. 121-122, Mar. 22, 1973. 
 ANE-8, pp. 19- 27, March,  1961.  62. 
 1040.—Trigatron. using anatmosphere ofrelativel yhigh-pressure hydrogen, thetemperature variation ofmercury vapor pressure ismade unimportant.Since the ordinary series. gap islimited inoperation bypitting and spike growth, the mercury cathode provides better operation over awide range of. 
 The samples,  stored in memory, can be manipulated in amplitude, frequency, and phase to generate a  wide range of jamming signals. The stored samples are later recalled, processed by the  digital-to-analogue converter (DAC), up converted, and transmitted back to the victim  radar.24 The information content of an intercepted radar signal is mainly carried in the  phase of the signal, and then the amplitude is usually discarded and only the phase  contribution is quantized and processed.25 The phase quantization is performed by the  DRFM by means of M bits into N = 2M levels. After the phase quantization, introduced  on the signal by the DRFM, the jamming signal is transmitted back to the victim radar  with an increasing delay with respect to the received radar signal. 
 The total  amount of sand in the box is fixed and corresponds to a fixed signal energy. No sand can be  added, and none can be removed. The sand may be piled up at the center (origin) to as narrow  a pile as one would like, but its height can be no greater than a fixed amount (2E)2. 
 AP-17, pp. 131-138, March, 1969.  96. 
 However, the five-horn feed is a E-PLANE TRANSMITTER TRDEVICE RECEIVER AZIMUTHDIFFERENCE ELEVATIONDIFFERENCE FRONT ELEVATIONDIFFERENCE SUM AZIMUTHDIFFERENCE . practical choice between complexity and efficiency. It has been used in several instrumentation radars including the AN/FPQ-6, AN/FPQ-10, AN/TPQ-18, and AN/MPS-369'10 and in the AN/TPQ-27 tactical precision-tracking radar.11 The multimode feed techniques can be expanded to other higher-order modes for error sensing and E-field shaping.12'13'14 The difference signals are contained in unsymmetrical modes such as the TE20 mode for //-plane error sensing and combined TE1, and TM11 modes for /i-plane error sensing. 
 The C/Lratio oftheresonators and ther-floading also affect the circuit efficiency. Circuit efficiencies forthe usual r-floading vary from close to100 per cent forthe 10oo- Mc/sec range to50percent forthe25,000-Mc/sec range. Realization ofhigh magnetron efficiency affects system design intwo ways. 
 FLYING AIRCRAFT  AS CLAIMED OR REPORTED FOR SEVERAL ESTABLISHED (&372 SYSTEMS 4!",%  .OMINAL OR #LAIMED -AXIMUM $ETECTION 2ANGES KILOMETERS  OF 3OME (&372  3YSTEMS   3EA3ONDE IS A COMPACT LOW 
 there is much more of a diurnal  variation of ducting over land than over sea, where it is likely to be more continuous and  wide~pread.~'  . Superrefracting ground ducts may also be produced by the diverging downdraft undcr a  tlii~nderstorm.~' The relatively cool air which spreads out from tlie base of a thunderstorm  results in a temperature inversion in the lowest few thousand feet. The moisture gradient is  also appropriate for the formation of a duct. 
 p. 592.  McGraw-Hill Book Company. 
 45, no. 1, January 1997. 42. 
 This will befurther discussed incon- nection with specific types ofdisplay. Indices orScaleMarkers.-Both mechanical and electrical means areused formaking geometrical meamrements onthedisplays. Inmeasuring range, “electronic” range markers are practically always used. 
 ARRAY v  0ROC OF )NT #ONF ON 2ADAR  2ADAR   7ASHINGTON  $#  53!  -AY n    PP n  , 4IMMONERI  ) + 0ROUDLER  ! &ARINA  AND * ' -C7HIRTER  h12$ 
 - 4HE OBJECTIVES OF AN %#- SYSTEM ARE TO DENY INFORMATION DETECTION  POSITION  TRACK INITIATION  TRACK UPDATE  AND CLASSIFICATION OF ONE OR MORE TARGETS  THAT THE RADAR SEEKS OR TO SURROUND DESIRED RADAR ECHOES WITH SO MANY FALSE TARGETS THAT THE TRUE INFORMATION CANNOT BE EXTRACTED n %#- TACTICS AND TECHNIQUES MAY BE CLASSIFIED IN A NUMBER OF WAYS  IE  BY MAIN  PURPOSE  WHETHER ACTIVE OR PASSIVE  BY DEPLOYMENT  BY PLATFORM  BY VICTIM RADAR  OR BY A COMBINATION OF THESE n  !N ENCYCLOPEDIA OF %#- TACTICS AND TECHNIQUES CAN  BE FOUND IN THE LITERATURE  (ERE DESCRIPTION IS LIMITED TO THE MOST COMMON TYPES  OF %#- %#- INCLUDES BOTH JAMMING AND DECEPTION  *AMMING IS THE INTENTIONAL AND DELIB 
 When the rising buoyant air is  separated from the ground it may break away and form a freely floating thermal (convective  cell). especially if there is a wind. Near the ground the convective cells might he a few tens of  meters in diameter. 
 RADAR CROSS SECTION  14.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 The plate is presented broadside to the incident wave at the center of the chart (0 °)  and is seen edge-on at the left and right sides (90 °). The large specular return from the  plate at the center of the chart is predicted with quite good accuracy by the flat-plate  formula given in Table 14.1, later in this section. The edge-on return for VV polariza - tion is well predicted by the straight-edge formula, also given in Table 14.1. 
 41. pp. 77 80, Fchruary, 1971. 
 STATE SWITCHES ARE BUILT FROM MODULES THAT MIGHT CONTAIN FROM  TO  INDIVIDUAL TRANSISTORS CONNECTED IN SERIES TO PROVIDE THE REQUIRED TRANSMITTER CATHODE VOLTAGE 2ISE TIMES CAN BE AS LOW AS  NS £ä°Ê 7 Ê,Ê*"7 
 By using Eq. 15.1, the period T ′ and wavelength Λ′ thereby  defined take the form  T ′ = 0.64 U   Λ′ = 0.64 U 2 (15.5) where U is in meters per second. For example, the largest waves in a fully developed  sea for a 15 kt (8 m/s) wind will have a wavelength of about 135 ft (41 m) with a  period of 5 s. 
 TARGET DICTATES THE NEED FOR A BATCH PROCESSING APPROACH 4HERE ARE MANY DIFFERENT COMBINATIONS OF SUCCESSFUL -4) TECHNIQUES  BUT ANY SPE 
 The echoes of all scattering objects, and not just the perfectly conducting sphere, can be grouped according to the electrical-size characteristics of the ob- ject. The dimensions of a Rayleigh scatterer are much less than a wavelength, and the RCS is proportional to the square of the volume of the body. Resonant scatterers are generally of the order of one-half to 10 wavelengths in size, for which neither Rayleigh nor optics approximations may be very accurate. 
 However, with complex atmospheric attenuation compensation and  doppler methods, weather can be detected well enough to allow warning and avoid - ance of storms. The principal challenge is compensating for backscatter from the  leading edge of a storm and adjusting for attenuation to see far enough into a storm to  evaluate its severity. The backscatter from each cell is measured, the power remaining  is calculated, the attenuation in the next cell is estimated, and then the backscatter in  the next cell is measured, and so on. 
 WAVELENGTH DIMENSION OR WITH THE FIRST RESONANCE &)'52%  4HE FREQUENCY DEPENDENCE OF THE 2#3 FOR AN  M LONG BY  M DIA METER  PERFECTLY  CONDUCTING CYLINDER  PRESENTED FOR VARIOUS ILLUMINATION GEOMETRIES 4HE % VECTOR AND THE  M DIMEN 
 TheareaAcinEq.(13.1)is(n/4)ROsR</>8 sin4>,where4>=grazing angle.Thefactornj4 accounts fortheelliptical shapeofthearea.Substituting AcintoEq.(13.3)andtaking G=n2jOs4>8,69theclutterradarequation is C='nPIAe(Jo 64R2sin4> Theclutterpowerisseentovaryinversely asthesquareoftherange.Equation (13.9)applies. forexample, tothesignalreceived fromtheground byaradaraltimeter. Anequation for detecting atargetinthistypeofclullerbackground couldbederived, butitisasituation not oftenfoundinpractice. 
 PARALLEL  PERPENDICULAR 
 M DIAMETER UMBRELLA 
 As stated previously, the radiated field of an antenna is related to the illuniination  across the aperture by the Fourier transform. Shelt~n~~ has pointed out that the flow diagram  of the FFT is basically similar to the diagram of the Butler network. Thus the Butler network  is a manifestation of the FFT. 
 FAN 
 ENT DATA RATES COMES THE NEED TO ADJUST THE RECEIVER FILTERING IN ORDER TO AVOID ALIASING SIGNALS BEYOND THE .YQUIST RATE !LTHOUGH THESE RADARS ADJUST THEIR FILTERING TO THE WAVEFORM BANDWIDTH  THEY DO NOT TYPICALLY IMPLEMENT THE MATCHED FILTERING WITHIN THE RECEIVER 4HIS FUNCTION IS USUALLY IMPLEMENTED IN DIGITAL SIGNAL PROCESSING 2ECEIVER &ILTERING  &ILTERING IS REQUIRED AT VARIOUS POINTS THROUGHOUT THE RECEIVER  CHAIN INCLUDING 2&  )&  BASEBAND IF USED  DIGITAL FILTERING PRIOR TO DECIMATION REDUC 
 The ISLR along the azimuth direction is −9.8859.  $]LPXWK5DQJH   (a) Imaging result of targets (b) Interpolation of a single point target     (c) Profiles of range-spread function (d) Profiles of azimuth-spread function  Figure 13. Imaging result of the backward-looking beam. 
   PP n    , " 7ETZEL  h%LECTROMAGNETIC SCATTERING FROM THE SEA AT L OW GRAZING ANGLES v IN  3URFACE 7AVES  AND &LUXES #URRENT 4HEORY AND 2EMOTE 3ENSING   CHAP   ' , 'EERNAERT AND 7 * 0LANT EDS    $ORDRECHT  .ETHERLAND 2EIDEL    , " 7ETZEL  h! TIME DOMAIN MODEL FOR SEA SCATTER v  2ADIO 3CI  VOL   NO   PP n   -ARCHn!PRIL   $ -IDDLETON AND ( -ELLIN  h7IND 
 Ó°{È  2!$!2 (!.$"//+  $EPTH OF &IRST .ULL IN 6ELOCITY 2ESPONSE  7HEN SELECTING SYSTEM PARAMETERS   IT IS USEFUL TO KNOW THE DEPTH OF THE FIRST FEW NULLS TO BE EXPECTED IN THE VELOCITY  RESPONSE CURVE !S DISCUSSED EARLIER  THE NULL DEPTHS ARE ESSENTIALLY UNAFFECTED BY FEEDBACK 4HEY ARE ALSO ESSENTIALLY INDEPENDENT OF THE TYPE OF CANCELER EMPLOYED  WHETHER SINGLE  DUAL  OR TRIPLE  OR OF THE NUMBER OF HITS PER BEAMWIDTH &IGURE  SHOWS APPROXIMATELY WHAT NULL DEPTHS CAN BE EXPECTED VERSUS THE RATIO OF MAXIMUM TO MINIMUM INTERPULSE PERIOD Ó°Ê  /Ê / 
 LOOP ELEVATION TRACKING RESUMES ! VERY EFFECTIVE AND DIRECT APPROACH TO MULTIPATH 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 
 HF receivers can employ direct digital conver - sion at RF, avoiding some of the limitations of analog devices. Issues such as recip - rocal mixing are still present, though in slightly modified form. Comparisons with  analog receivers have demonstrated that little or no penalty is incurred with such  designs if a band preselector filter is installed at the front-end. 
 SEA CLUTTER  15.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 Although such composite-surface models may leave the impression that they have  emerged as a rigorous product of an integral formulation of the GBVP, it is clear that  they are not really scattering theories , but instead scattering pictures  assembled from  a group of more or less plausible assumptions. But with the failure of the more formal  GBVP theories to provide a general framework for predicting and understanding sea  clutter, these models have become the basis for most analytical approaches to micro - wave scattering from the sea. Figure 15.19 compares a sample of NRL 4FR data taken at high wind speeds   (> 22 kn) with the predictions of the pure SPM Bragg  model (in the form of Eq. 
 Thusamedium resolution radarmighthavea 20dBadvantage overlow-resolution radarsinthedetection oftargetsinlandclutter.The. RADAR CLUTTER 4%  Downtown phoenix  Highest med~on value  SS = 1000  Phoerr~x SS > 25.000  N J residenlial  Ar~zona mountainous  T~rlzono culllvated farmland N J morshland I  - 50 -  10 I I I -60% I I I I I  UHF 1000 L C X 10,000  Frequency (MHz)  0  UJ 0 -10-  0 b  6 w  -601 I I I I I I UHF 1000 L C X 10,000  Frequency,(MHz)  (b) I I -  Downtown phoen~x  Hlqhest med~on volue  - SS = 1000  Phoenix, SS .25,000  N J residential 8 I  6 -20 - -  C 3  L w 0  c 30 0 - +- U  w VI  VI  -40 u  -50  Figure 13.1 1 Median valries of no as a function of frequency. Grazing angle = 8". 
 J. J. Hennelt. 
 AROUND ECHOES FROM METEOR IONIZATION AND AURORA 4HE RADAR CROSS SECTION OF AIRCRAFT AT 6(& IS GENERALLY LARGER THAN THE RADAR CROSS SECTION AT HIGHER FREQUENCIES 6(& RADARS FREQUENTLY COST LESS COMPARED TO RADARS  WITH THE SAME RANGE  PERFORMANCE THAT OPERATE AT HIGHER FREQUENCIES !LTHOUGH THERE ARE MANY ATTRACTIVE ADVANTAGES OF 6(& RADARS FOR LONG 
 SIDERATIONS ON HARDWARE THAT ARE CHARACTERISTIC OF AND ESSENTIALLY UNIQUE TO  THE SPACE ENVIRONMENT INCLUDE RADIATION AND ENERGETIC PARTICLES  VIBRATION ESPECIALLY DURING THE LAUNCH PHASE   HARSH AND CONTRASTING THERMAL ENVIRONMENTS  OFTEN CHALLENGING MASS LIMITATIONS  AND A PREMIUM ON PAYLOAD POWER )N %ARTH ORBIT AND  PERHAPS SUR 
 It generates a highly concentrated high-energy  linear beam of electrons that interacts with the microwave structure (two or more micro - wave cavities) to achieve amplification. Another example of the linear-beam tube is the  traveling wave tube  (TWT) amplifier. It generally can do almost what a klystron can  do, but it is capable of very wide bandwidth at low powers, which the klystron is not. 
 218-223, American Meteorological Society, Boston, 1961. 73. Browning, K. 
 TION IS KNOWN AS A  STANDARD GRADIENT AND IS CHARACTERIZED BY A DECREASE OF   . 
 Table 13.3 Radar cross sections of birds9'  Frequency Mean radar Median radar  Rird batid cross section (cm2) cross section (cm2)  Sparrow ,Y  S  0111:  described statistically. There is some evidence to indicate that the probability density function  for the radar cross section of (or received power from) a single bird in flight is log-normal. The  nican-to-median ratio of the cross section, which is a measure of the amount of fluctuation in  the cross section, is found to be independent of the magnitude of the radar cross section but is  a function of the physical size of the bird relative to the radar ~avelength.~' Thus measure-  ments of the mean-to-median ratio might be used to determine the size of the bird b-ing  observed. 
 MS RESOLUTION CELL IN THE MOUNTAINOUS REGION OF ,AKEHEAD  /NTARIO  #ANADA  4HE 00) RANGE IS SET FOR  NMI  #LUTTER THAT EXCEEDS THE MINIMUM 
 23 to 13.24 3D search, 13.4 theory, 13.9 to 13.15 time-delay networks, 13.44 to 13.45 time-delay scanning, 13.7 tracking with, 7.46 Volume Search Radar (VSR), 13.62 to 13.63 wide bandwidth operation, 13.6 Phase shift in DSP, 25.22 to 25.25 Physical optics, 14.21 to 14.24 and ground echo, 16. 9 to 16.10 reflector analysis, 12.31 to 12.33 Physical theory of diffraction, 14.25 to 14.26 Pilotage and CMR, 27.31 Pioneer Venus, 18.44 Planar array, 13.15 to 13.19 Planetary radars, 18.43 to 18.53 atmospheric sounding, 18.62 to 18.63 Cassini, 18.46 Clementine, 18.46 to 18.47 cloud profiling, 18.63 fl ight systems, 18. 43, 18.56 to 18.58 ice exploration, 18.47 to 18.48 ionospheric sounding, 18.62 Magellan, 18.45 to 18.46, 18.48 to 18.52 polarization, 18.52 rainfall measurement, 18.62 scatterometers, 18.53 to 18.58 sounders, 18.59 to 18.63 table of, 18.44 Venera, 18.43 to 18.45 Plasma frequency, 20.2 Platform motion, in AMTI, 3.3 to 3.14 compensation abeam, 3.10 to 3.14 forward direction, 3.21 to 3.23 and scan compensation, 3.18 to 3.21 P(n,k) polyphase codes, 8.22 to 8.24 Point-clutter scatterers, 2.18 to 2.19 Polarimetric SAR, 17.22 Polarization and ground echo, 16. 
 Li32hasdescribed experiments usingalO-ft-diameter spherical reflector atafrequency of11.2GHz.Thefocallengthwas 29.5in.Ifthephaseerrorfromthesphereistodifferfromthatofaparaboloid bynomore thanA/16.themaximum permissible diameter oftheilluminated surfaceshouldbe3.56ft.The heamwidth required oftheprimary feedpatternisdetermined bytheilluminated portionof theaperture.Liusedasquare-aperture hornwithdiagonal polarization inordertoobtainthe required primary beamwidth andlowprimary-pattern sidelobes (betterthan25dB).The Centerof sphere Figure7.15Stepped parabolic reflector.. 246 INTRODUCTION TO RADAR SYSTEMS  resulting secondary beamwidth from the sphere was about 1 .8" (39.4 dB gain) with a relative  sidelobe level of 20 dB. A total useful scan angle of 140" was demonstrated. 
 (ILL     , % -ERTERS AND 2 ( 4ABELING  h4RACKING INSTRUMENTATION AND ACCURACY ON THE %ASTERN 4EST  2ANGE v )%%% 4RANS  VOL 3%4 
 .13 16 Sub-array 4  formation. .17 24 Digital tapering for difference beam formation Σ ∆Tapering wi at element level RX & ADC RX & ADC RX & ADC RX & ADCj j j j j j j . .Analogue sectionPhase shifters ch24.indd   27 12/19/07   6:00:43 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Repeat tolerance usually is the condition that motivates active  orbit maintenance maneuvers. Non-Repeat Orbit.  The precedent for this is Geosat71; its first 18 months were  devoted to geodesy for which a non-repeat orbit is optimal. 
 The use of a fan beam with such a system permits  the simultaneous measurement of scattering coefficients at points ahead of and behind  the aircraft carrying the radar. Figure 16.15 shows this. The pattern of the antenna illu - mination on the ground is shown intersected by two isodops (lines of constant doppler  frequency), with the width of the spectrum between them shown on the diagram. 
 SENTED PERPENDICULAR TO THE INCIDENT WAVE IS  R   , O (OWEVER  THIS ESTIMATE IS SOME   D" LOWER THAN THE PEAK AMPLITUDE ATTAINED IN &IGURE  BY THE LEADING 
 ING OF THIS DETECTOR IS THAT IT IS FAIRLY SUSCEPTIBLE TO TARGET SUPPRESSION EG  IF A LARGE TARGET IS IN THE REFERENCE CELLS  THE TEST CELL CANNOT RECEIVE THE HIGHEST RANKS  )F THE TIME SAMPLES ARE CORRELATED  THE RANK DETECTOR WILL NOT  YIELD #&!2 ! MOD 
 A peak occurs when the platform motion is a multiple of a quar- ter wavelength. The clutter-to-noise-ratio limitation results in cusping not beingADAPTED UNADAPTED ADAPTED UNADAPTEDIMPROVEMENT FACTOR (dB) IMPROVEMENT FACTOR (dB) . FRACTIONAL ENVELOPE SHIFT 8/T0 FIG. 
 ATION FOR THE CYLINDER INCLUDES FICTITIOUS CONTRIBUTIONS FROM THE SHADOW BOUNDARIES AT THE SIDES OF THE CYLINDER THAT DO NOT APPEAR IN A STATIONARY PHASE APPROXIMATION  4HE AMPLITUDE OF THE ELEMENTAL SURFACE CONTRIBUTIONS CHANGES SLOWLY OVER THE SURFACE  OF INTEGRATION WHEREAS THE PHASE CHANGES MUCH MORE RAPIDLY !S SUCH  THE NET CONTRIBU 
 THE 
 ARRAYS AND A NUMBER  . OF ROWS EQUAL TO THE NUMBER OF ELEMENTARY RADIATORS 4HE ELEMENT  TIJ OF THE MATRIX IS  DEFINED EITHER AS  WI IF THE I 
 25.27  Time Synchronization  ........................................  25.27  Phase Synchronization and Stability  ..................  25.28  Index   ............................................................................... 
 S’ubchdter Vi.sibik@-From Eq. (28) we see that the subclutter visibility can beincreased byincreasing nand A.f,,but that nothing much isgained bygoing greatly beyond thepoint where thescanning and wind fluctuations are equal tothose due tosystem instability. Awell-de- signed system might have anrms instability of2percent, inwhich case, from Eq. 
 SHARED BASIS FOR BOTH TRANSMITTING AND RECEIVING 4HE FUNCTION OF THE  DUPLEXER IS TO ALLOW A SINGLE ANTENNA TO BE USED BY PROTECTING  THE SENSITIVE RECEIVER FROM BURNING OUT WHILE THE TRANSMITTER IS ON AND BY DIRECTING THE RECEIVED ECHO SIGNAL TO THE RECEIVER RATHER THAN TO THE TRANSMITTER 4HE ANTENNA IS THE DEVICE THAT  ALLOWS THE TRANSMITTED ENER GY TO BE PROPAGATED INTO  SPACE AND THEN COLLECTS THE ECHO ENERGY ON RECEIVE )T IS ALMOST ALWAYS A DIRECTIVE ANTENNA  ONE THAT DIRECTS THE RADIATED ENERGY INTO A NARROW BEAM TO CONCENTRATE THE POWER AS WELL AS TO ALLOW THE DETERMINATION OF THE DIRECTION TO THE TARGET !N ANTENNA THAT PRODUCES A NARROW  DIRECTIVE BEAM ON TRANSMIT  USUALLY HAS A LARGE AREA ON RECEIVE  TO ALLOW THE COLLECTION OF WEAK ECHO SIGNALS FROM THE TARGET 4HE ANTENNA NOT ONLY CONCENTRATES THE ENERGY ON TRANSMIT AND COLLECTS THE ECHO ENERGY ON RECEIVE  BUT IT ALSO ACTS AS A SPATIAL FILTER TO PROVIDE ANGLE RESOLUTION AND OTHER CAPABILITIES p  )N RADAR   RANGE IS THE TERM GENERALLY USED TO MEAN DISTANCE FROM THE RADAR TO THE TARGET 2ANGE IS ALSO USED HERE IN  SOME OF ITS OTHER DICTIONARY DEFINITIONS. 
 pp.  177 183. April. 
 If H stands for linear horizontal polarization, t/ for linear vertical, and if the first  letter of a two-letter grouping denotes the transmitted polarization and the second lzttzr  denotes the polarization of the received signal, then the polarization matrix requires knowl-  edge of the amplitudes and phase of the following components: HH, V V, H V and V H. H V  and VH are sometimes called the cross polarization components. In general H V = VH so that  only one need be determined. 
 8  AND 2)3!4 )T IS ARGUED THAT ACTIVE ARRAYS SET THE STAGE FOR hGRACEFUL FAILUREv SINCE THE LOSS OF A FEW 42 ELEMENTS WOULD HAVE LITTLE EFFECT ON THE NET PERFORMANCE OF THE SYSTEM )N PARALLEL  AN ALTERNATIVE 3!2 ANTENNA PARADIGM STRESSES SIMPLICITY AND LOWER MASS AND LOWER COST  OVER TWO 
 FINDING RADAR 4HIS ERROR COULD LEAD TO SIGNIFICANT TACTICAL CONSEQUENCES IN A SHIPS SELF 
 CIALLY AT HIGHER RADAR CARRIER FREQUENCIES 4HIS LOSS IS A FUNCTION OF RANGE  ALTITUDE  AND WEATHER )T IS ALSO A TWO 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation.  THE PROPAGATION FACTOR, FP, IN THE RADAR EQUATION  26.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 While a graphic may be useful for visual inspections, it may not be useful for an  engineering analysis task. 
 60. L. M. 
 This simple system can lead tooccasional unnecessary interference ofone interrogator with another. Let usassume, for example, that there arebut twointerrogators and that thebeacon could readily reply toboth steadily. Ifthedead time islong, there will never- theless betimes when the interrogations from one beacon will arrive in thedead time following thereply totheother. 
 Gossard. E. E., D. 
 On the night of July 25th, the USS  Mississippi gained radar contact with what was believed to be Japanese fleet units mov - ing toward Attu in order to withdraw troops. Radars onboard the USS New Mexico,  the USS Portland, and the USS Wichita confirmed the radar contacts. On the orders of  Admiral Giffen, the U.S. 
 In addition to the radar system designer, it is hoped that those who are responsible for procuring new radar systems, those who utilize radars, those who maintain radar systems, and those who manage the engineers who do the above, also will find the Radar Handbook  to be of help in fulfilling such tasks. The third edition of the Radar Handbook  is evidence that the development and application of radar for both civilian and military purposes continue to grow in both utility and in improved technology. Some of the many advances in radar since the previous edition include the following: - The extensive use of digital methods for improved signal processing, data processing, decision making, flexible radar control, and multifunction radar - Doppler weather radar - Ground moving target indication, or GMTI-  An extensive  experimental  database  describing low-angle  land  clutter,  as  obtained  by  MIT  Lincoln Laboratory, that replaced the previously widely used clutter model that dated back to World War II - The realization that microwave sea echo at low grazing angles is due chiefly to what are called “sea spikes”- The active-aperture phased array radar system using solid-state modules, also called active electronically scanned arrays (AESA), which is attractive for some multifunction radar applications that need to manageboth power and spatial coverage - Planetary exploration with radar - Computer-based methods for predicting radar propagation performance in realistic environments. 
 Itisthis ratio, which weshall callF,that wewant now tocompute. The difference inlength between thepaths All and AMB, iftheangle oissmall, isgiven quite closely by Xim-m=y. (24) This isresponsible foradifference inelectrical phase of4rhlh,/RA radians between thetwo waves arriving atB,towhich wemust add any phase klG.29.-Pr0pagati0n over aflatreflecting surface shift ~resulting from the reflection ofthe one wave atM. 
 FED FOCAL FEED EXAMPLE SHOWN IN &IGURE   THE SIMPLER  APERTURE 
 CONVERSION WITH THE MATCHED FILTER IMPULSE RESPONSE SEQUENCE "ECAUSE TIME 
 OUT CAN COMPLETELY INCA 
 356–365, November 1967. 44. A. 
 WAY ANTENNA BEAMWIDTH  A   SERVO BANDWIDTH  (Z ! SAMPLE CALCULATION FOR AN  FS OF  (Z  WHERE  !FS  FROM MEASURED DATA TAKEN ON A  LARGE JET AIRCRAFT IS APPROXIMATELY  (Z  P" IS  MILS  AND  A IS  (Z  GIVES A  RS  OF  MIL RMS )N THE CASE OF A PERIODIC MODULATION  WHERE A SPECTRAL LINE FALLS WITHIN THE BAND   FS o A  THE RMS NOISE IS  RS   P" !FS   WHERE !FS  IS THE RMS FRACTIONAL MODULATION  CAUSED BY THE SPECTRAL LINE 4HE RESULTANT RMS TRACKING ERROR  RS WILL BE PERIODIC AT THE  FREQUENCY FS  FT WHERE FT IS THE FREQUENCY OF THE SPECTRAL LINE 4HE EFFECTS OF AMPLITUDE NOISE ON TARGET DETECTION AND ACQUISITION ARE OF CONCERN IN  ALL TYPES OF RADARS  PARTICULARLY AT LONG RANGES WHERE THE SIGNAL IS WEAK 4HE AMPLITUDE  FLUCTUATIONS CAN CAUSE THE SIGNAL TO DROP BELOW THE NOISE LEVEL FOR SHORT PERIODS OF TIME   THUS AFFECTING THE CHOICE OF THRESHOLDS  ACQUISITION SCAN RATE  AND DETECTION LOGICn !NGLE .OISE 'LINT   !NGLE NOISE CAUSES A CHANGE WITH TIME IN THE APPARENT  LOCATION OF THE TARGET WITH RESPECT TO A REFERENCE POINT ON THE TARGET 4HIS REFERENCE POINT IS USUALLY CHOSEN AS THE  CENTER OF hGRAVITYv OF THE REFLECTIVITY DISTRIBUTION ALONG  THE TARGET COORDINATE OF INTEREST 4HE CENTER OF GRAVITY IS THE LONG 
 The signal-to-noise ratio of the initial signal synthesizer must meet the requirements. The lower-level signal amplification can generally be designed to add no noise. Mechanical vibra- tion in the high-power amplifiers can add noise, and care must be exercised in the air or liquid coolant flow system design. 
 26 to 22.27 Radar applications of, 1.20 to 1.22 bandwi dth in, 1.8 to 1.9 basic parts of, 1.2 beacons, in CMR, 22.25 blinking for ECCM, 24.37 block diagram, 1. 3 in brief, 1.1 conceptual system design, 1.22 to 1.23 cross section of aircraft, 14.13 to 14.14 approximate methods, 14.19 to 14.27 approximations for simple scatterers, 14.10. basic echo mechanisms, 14.2 to 14.4 of birds, 14.11 bistatic, 23.19 to 23.21 of bodies of revolution, 14.39 to 14.40 characteristics, 14.5 to 14.16 of complex objects, 14.11 to 14.16 of a corner reflector, 14.9 to 14.11 definition of, 14.4 to 14.5 exact methods, 14.16 to 14.19 at HF, 20.26 to 20.29 general, for various target types, 14.16 of insects, 14.11 to 14.12 of a man, 14.11 to 14.12 measurement ranges, 14.30 to 14.35 measurement techniques, 14.27 to 14.35 of a metal plate, 14. 
  AND # 
 South is in the up direction.  Resolution is 5 ft (l.5 m) in azimuth and 7 ft (2.l m) in range. (Courtesy £1wiro11.me11tal Research lnstit11te  of Michigan.) . 
 Jn a military radar, a low-noise receiver can make the radar more susceptible to the effects  of deliherate electronic countermeasures (ECM). When practical, it may be preferred to delib­ erately employ a conventional receiver with modest sensitivity and to make up for the  reduced sensitivity by larger transmitter power. This is not the most economical way to build a  radar. 
 Trunk, “Detection results for scanning radars employing feedback integration,” IEEE Trans .,  vol. AES-6, pp. 522–527, July 1970. 
 RANGE CIRCLES AND THE  ISODOPS 4HE hNADIR LINEv SHOWN  IN &IGURE  IS THE LOCUS OF SUBRADAR POINTS AS THE PLATFORM FLIES ALONG ITS PATH &)'52%  2ANGE AND VELOCITY CONTOURS ON  THE %ARTHS SURFACE  A  #OLLECTION GEOMETRY  B  #ONSTANT 
 Any use is subject to the Terms of Use as given at the website. Ground Echo. 16.16  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 A pulse of length t  is transmitted from an antenna of beamwidth f0. We may simplify  the problem by assuming a rectangular illuminated area, Rf0 ct/(2 sin q). 
 15.4. Increasing theelevation angle ofsection AD ofthecontour does notadd greatly tothe radar coverage requirements, since the region issmall; but practical difficulties ofantenna design are encountered. Since close-in regions have been inthepast largely masked out bypermanent echoes, anangle of30°was considered acceptable. 
 This is clearly illustrated in the side view of the AN/TPS-43 antenna of Fig. 6.16. If that feed is examined carefully, one can also see that off-axis feeds become progressively larger so as to form progressively wider elevation beams that main- tain a nearly constant number of beamwidths off axis. 
 TIONAL TOOLS TO RADAR ENGINEERS AS WELL AS THE GENERAL PUBLIC SINCE THEIR INTRODUCTION BY  THE 5NITED 3TATES .ATIONAL 7EATHER 3ERVICE .73  IN THE S AND ARE WIDELY USED BY WEATHER FORECASTERS IN THE PUBLIC AND PRIVATE SECTORS -AJOR TECHNICAL IMPROVEMENTS WERE INTRODUCED IN THE S WHEN THE .73  THE &EDERAL !VIATION !GENCY &!!   AND THE 53 !IR &ORCE JOINED TOGETHER TO INSTALL THE NEXT GENERATION NATIONAL NETWORK OF 732 
 608 618, September, 1975.  50. Illahy. 
 Lilrlitilig in the radar receiver can lower the probability of detection. Altllougl~ a  well-tlcsigtlcd and cngirlcered receiver will not limit the received signal under normal circum-  starices. ir~tensity rrlodulated CR'T displays such as the PPI or the B-scope have limited dyna-  mic range and may limit. 
 £n°xn  2!$!2 (!.$"//+  SINUSOIDALLY OVER  -(Z DURING EACH ANTENNA ROTATION )NSTRUMENT MASS IS  KG  REQUIRED INPUT POWER IS  7 4HESE NUMBERS ILLUSTRATE THE PRINCIPAL ADVANTAGES OF THE ARCHITECTURE  PROVIDING GREATER COVERAGE WITH LESS MASS AND POWER  IN CONTRAST TO THE STICK 
 Majewski, Spotlight Synthetic Aperture Radar —Signal  Processing Algorithms , Boston: Artech House, 1995. 36. C. 
 Analysis has shown that a 3-dB increase in the transmitted confirmation energy  (additional energy is also available by placing the target in the center of the confirma - tion beam) can significantly increase the probability of confirmation.76 Furthermore,  the confirmation dwell should be transmitted as soon as possible to maintain a Swerling   I fluctuation model. (That is, if the target was originally detected when the target fluc - tuation produced a large return, the confirmation dwell will see this same large return.)  After confirmation, a series of initial track maintenance dwells over several seconds is  used to develop an accurate state vector. A complete discussion of priority associated  with tracking within the scheduler of a phased array is beyond the scope of this brief  discussion. 
 P. Hyberg, “Assessment of modern coherent jamming methods against synthetic aperture radar  (SAR),” Proc. of EUSAR ’98 , European Conf. 
 Aerosp. Electron. Syst. 
 (13.8) that should be noted. The transmitter  power does not appear explicitly. Increasing the transmitter power will indeed increase the  target signal, but it will also cause a corresponding increase in clutter. 
 The average value or the median might be taken.  Sometimes it is a " minimum" value, perhaps the value exceeded 99 percent of the time or 95  percent of the time. It might also be the value which when substituted into the radar equation  assures that the computed range agrees with the experimentally measured range. 
 In  addition, as the aircraft flies directly over a piece of terrain, combined terrain profile is  verified by a radar altimeter function (TERCOM/TERPROM) in the RF and processor  complex. Usually the prestored data is generated at the required resolution before a  mission from the worldwide digital terrain elevation database (DTED). Sea Surface Search, Acquisition, and Track. 
 2011 ,91, 2359–2370. [ CrossRef ] 26. Giurcaneanu, C.; Saip, F.A.A. 
 TORS OR A ,UNEBURG LENS TO SIMULATE FIGHTER OR BOMBER AIRCRAFT 4HE OBJECTIVE OF DECOYS IS TO CAUSE A DILUTION OF THE ASSETS OF THE DEFENSIVE SYSTEM  THEREBY INCREASING THE SUR 
 L. R., et al.: Terminology in Digital Signal Processing, IEEE Trans., vol. AU-20,  pp. 
 BE AM CLUTTER IS THE LARGEST  SIGNAL  7ITHOUT A CANCELER  HEAVIER WEIGHTING IS NEEDED TO REDUCE SIDELOBES TO A LEVEL SO THAT THE FILTER RESPONSE TO MAIN 
 TRIBUTION OF NOISE FROM THUNDERSTORMS  INDUSTRIAL SITES AND OTHER SOURCES IS FAR FROM  UNIFORMLY DISTRIBUTED &URTHERMORE  EVEN SO 
 Because this basic material may beofgreat value toscience and engineering, itseemed most important topublish itassoon assecurity permitted. The Radiation Laboratory ofMIT, which operated under the super- vision oftheNational Defense Research Committee, undertook thegreat task ofpreparing these volumes. The work described herein, however, is the collective result ofwork done atmany laboratories, Army, Navy, university, and industrial, both inthis country and inEngland, Canada, and other Dominions. 
 The fighter  aircraft pulse doppler geometry is centered around the aircraft traveling at a velocity,  Va, and at an altitude, h, above the Earth’s surface. The radar pulse repetition frequency FIGURE 5.7  MFAR priority scheduling ch05.indd   7 12/17/07   1:26:39 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 has been limited by its  relatively high cost. The phase-phase array is what is generally implied when the term  electrn11ically steered phased array is used.  The phased array antenna has seen application in radar for such purposes as aircrart  surveillance from on board ship (AN/SPS-33), satellite surveillance (AN/FPS-85). 
 The entire measuring system can be described with the scattering m a- trices upon this basis:     € Sm[]=I[]+R[]Sc[]T[] (11.10)  In component form Equation (11.10) reads:  . Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 97     € ShhmShvm SvhmSvvm        =IhhIhv IvhIvv        +RhhRhv RvhRvv        ShhcShvc SvhcSvvc        ThhThv TvhTvv         Sc[]=correct, wanted magnitudes Rξη=receiving path Tξη=Transmission path Iξη=isolation Sm[]=maesurable magnitudes (11.11)  Indices describe the respective polarizations (horizontal a nd vertical).  Same indices mean co - polarization and different indices mean cross -polarization. 
 SCAN BASIS  SCANS OF DATA ARE TYPICALLY USED IN THE ANALYSIS 4HE RESULTANT INFORMATION CAN BE HIGHLY USEFUL FOR LARGE HIGH 
 BEAM ILLUMINATION PATTERN AND B   USE WITH A FAN BEAM.   '2/5.$ %#(/  £È°ÓÎ &IGURE B SHOWS AN ANTENNA PATTERN THAT TAKES BETTER ADVANTAGE OF THE POSSIBILI 
 Conf.  Radar-82 , London, October 18–20, 1982, pp. 278–282. 
 21. S. W. 
 3HALOM AND 4 &ORTMANN   4RACKING AND $ATA !SSOCIATION   /RLANDO  &, !CADEMIC 0RESS     2 7 3ITTLER  h!N OPTIMAL ASSOCIATION PROBLEM IN SURVEILLANCE THEORY v  )%%% 4RANS  VOL -), 
 39. Gerard, W. A.: Frequency-Agile Coaxial Magnetrons, Microwave J., vol. 
 For an array, samples are taken of the continuous  distribution at each of the discrete locations. Some typical illumination functions are  given in Table 13.1. It is seen that uniform illumination (constant amplitude) results  in the highest gain and the narrowest beamwidth but at the cost of high sidelobes. 
 TRACK  FUSION IS CONSIDERABLY MORE ACCURATE 4HIS IS EASILY EXPLAINED BY THE FACT THAT THE PROB 
 AP-8,  pp. 347-349, May, 1960.  27. 
 TOR PROBLEMS  SO THAT ITS SENSITIVITY NOISE 
 E. Barrios, “Advanced Propagation Model (APM) Computer Software Configuration Item  (CSCI),” Space and Naval Warfare Systems Center TD 3145, August 2002. 19. 
 Radar Target Enhancers.  Radar target enhancers35 (RTEs) are used increas - ingly by small craft because, for their size, they offer a better enhancement in radar  cross section than can be given by a passive reflector. In principle, they are simple  devices. 
 The ambiguity function is defined on page 55 using the standard - ized definition given by Sinsky and Wang. 80. L. 
 This is known as radar signal management and is an important function of  the computer. In the AN/FPS-85 satellite-surveillance radar, for example, seven different radar  waveforms were available for performing the target detection and tracking mission as shown  in Table 8.1.118 An eighth waveform was used for alignment of the transmitter and receiver  modules.  The search and detection function requires that the computer generate the angular coor­ dinates of !he region to be searched, the type of transmitted waveform to be used, the length of  the dwell period, and the time assigned for the execution of the dwell by the radar. 
 Lopes, A.; Nezry, E.; Touzi, R.; Laur, H. Maximum a Posteriori Filtering and First Order Texture Models in SAR Images. In Proceedings of the 10th Annual International Symposium on Geoscience and Remote Sensing, College Park, MD, USA, 20–24 May 1990; pp. 
 € σξn=lim R→∞4πR2⋅Sξn2 (11.5)   The polarization scattering matrix additionally contains phase and polarization information.   As is to see from Equation (11.4) and (11.5), the observation distance R is also a parameter, whereby in practice it is only possible to evaluate the parameters relative to each other.  In  order to eliminate the disadvantages of the conventional definitions of σ and [ S ], which were  introduced in the previous sections, in the following section 2 new terms will be derived, which more adequately fulfill the requirements of coherently measuring Radar systems. 
 DOTTED LINE TWO 
 The surface of the cube was divided into 384 patches (64 patches per face), which was about the limit of the central memory of the Cyber 750 computer used in the computations. It required more than 2 h for the Cyber 750 to generate the data plotted in the figure.26 Approximate Methods. Approximate methods for computing scattered fields are available in both the Rayleigh and the optics regions. 
 and G. Brunins: Long Range Surveillance Radars for Automatic Control Systcms.  I EEE 1975 Itttc~r.ttcrriot~ul Rtrdur: C'or~l~rctrc.r~. 
 GAIN ANTENNA AS SHOWN IN &IGURE   FOR THE 3," 4HE RADAR OPERATES IN FREQUENCY DIVERSITY MODE  IE  IT RADIATES A BURST OF  , PULSES 4 SECONDS APART   WITH SLIGHTLY DIFFERENT CARRIER FREQUENCIES  4HE GRATING LOBES IN THE ADAPTED MAIN  AND THE , 3," PATTERNS WILL CHANGE AS A FUNCTION OF THE CARRIER FREQUENCY 4AKING  THE MAX OF THE OUTPUT OF THE  , 3," SIGNALS IS EQUIVALENT TO A SMOOTHING OF THE GRAT 
 10.11 does not sum all the range cells as described above, but sums the cells ahead of the  test cell separately from the sum of the cells following the test cell. The threshoid is determined  by whichever of the two sums is the greater. This is done to minir ize the generation of false  alarms at the leading and trailing edges of abrupt clutter regions.: <\. 
 elevation angle increases, the transmitted power is decreased as the elevation angle is in­ creased. (This is sometimes called power programming.) In a shipboard application, the eleva­ tion scanning control can be used to electronically stabilize the beam position to compensate  for ship's motion.  In a normal frequency-scan radar, the beam dwells at each angular resolution cell (beam­ width) for one or more pulse repetition intervals. 
 SYNTHETIC APERTURE RADAR  17.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 17.7 SUMMARY OF KEY SAR EQUATIONS A review of the basic equations of SAR follows: ● Range resolution = dr ≅ c/2B (c = speed of light, B = pulse bandwidth) ● Crossrange resolution = dcr ≅ l  /2∆q  (l = wavelength, ∆q = angle subtended by synthetic aperture) ● Physical beamwidth ≅ l  /D (D = antenna diameter)FIGURE 17.9  SAR image of the Washington Monument: The SAR image shows the side of the Monument  that is on the opposite side of the shadow, which may appear counterintuitive to a human observer. ( Courtesy  of General Dynamics, Ypsilanti, Michigan ) ch17.indd   21 12/21/07   2:44:07 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The kind of clutter environment,  the system instabilities, and the signal processing utilized determine where the system  performance will fall between the above two extremes. Unless provision is incorpo - rated for coping with system instabilities and clutter spectral spread, the MTI pulse  compression system may fail to work at all in a clutter environment. Ideally, a pulse compression receiver coupled with an MTI would appear as in  Figure 2.80 a.‡ If the pulse compression system was perfect, the compressed pulse  would look as if the radar had transmitted and received a short pulse, and MTI pro - cessing could proceed as if the pulse compression had not existed. 
 FadingoftheHFsignalscanoccurduetotherotation oftheplaneofpolarization overthe ionizedregionofthepropagation path.Multipath interference frommorethanonerefracting region,aswellasdynamic irregularities intheionospheric propagation path,aretwoother sourcesoffading. Thespecificregionontheearth'ssurfaceilluminated byanHFradardepends oniono­ sphericconditions. A..typical" patchofthegroundilluminated byasinglefrequency mightbe about1000kmintherangecoordinate. 
 MISSION TO REPRODUCE INFORMATION FROM ITS )NTERNATIONAL 3TANDARD )%#  ED   !LL SUCH EXTRACTS ARE COPYRIGHT OF )%#  'ENEVA  3WITZERLAND !LL RIGHTS RESERVED &URTHER INFORMATION ON THE )%# IS AVAILABLE FROM WWWIECCH )%# HAS NO RESPONSIBILITY FOR THE PLACEMENT AND CONTEXT IN WHICH THE EXTRACTS AND CONTENTS ARE REPRODUCED BY THE AUTHOR  NOR IS )%# IN ANY WAY RESPONSIBLE FOR THE OTHER CONTENT OR ACCURACY THEREIN , 
 Ogg: Statistically Designed Density-tapered Arrays, I £EE  Trans., vol. AP-12, pp. 408-417, July, 1964. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 Inthe case ofbeacon reception, automatic frequency control main- tains the local oscillator atapredetermined frequency that ishigher or lower than the frequency ofthe distant beacon transmitter byjust the intermediate frequency. RadarAFC,—A1l forms ofradar AFC work onthe same basic prin- ciple. Part ofthe local-oscillator power ismixed, inacrystal, with a small fraction ofthe magnetron power drawn out during transmission ofthe pulse. 
 First, allamplitudes aregreatly re- duced, asisdiscussed indetail in Chap. 2. Second, the scattering cross section ofthe target is,in general, afunction ofo;thevarious amplitudes are therefore not equally reduced. 
 Careful observation of performance-monitoring instru-  ments and timely preventative maintenance can do much to keep radar performance up to  design level. Radar cllaracteristics that might be monitored include transmitter power, receiver  noise figure, the spectrum and/or shape of the transmitted pulse, and the decay time of the TR  tube.  A good estimate of the field degradation is difficult to obtain since it cannot be predicted  and is dependent upon the particular radar design and he conditions under which it is  operating. 
 One of the harmorlics of.f, is selected (in this case the third) by a filter centered at  the harmonic. The filter bandwidth is wide enough to pass both doppler-frequency sidebands.  The filter output is mixed with the (third) harmonic of,fm. 
 T able 10. Comparison with other method. Method Accuracy (%) f1-Score Our Method 98.52 0.9715 Method in [ 5] 97.62 0.9565 Method in [ 17] Unknown 0.9443 Method in [ 38] Unknown 0.9404 3.9. 
 Tracking bandwidth is usu - ally limited to that necessary for tracking to minimize loss of track to false targets and  countermeasures. Many other electronic range-tracking techniques also offering most of  these advantages are used.22 nth-Time-Around Tracking.  To extend unambiguous range by reducing the  PRF increases the acquisition time and reduces the data rate. 
 ING IN BETTER SENSITIVITY IN NON 
 The tracking data from a radar tracking a target with a beacon is plotted in  Figure 9.27, showing a typical multipath error illustrating the phenomenon from the  region where the image enters the sidelobes to the region where it enters the main  beam. There are three methods used for predicting multipath errors, depending  upon where the reflected target image enters the antenna pattern. At the far range,  FIGURE   9.27  Measured elevation-tracking error of an S-band radar using an AN/FPS-16 radar for a target  elevation reference ch09.indd   38 12/15/07   6:07:48 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 On reception, the frequency-modulated echo is passed through the  pulse-compression filter, which is designed so that the velocity of propagation through the  filter is proportional to frequency .. When the pulse-compression filter is thought of as a  dispersive delay line, its action can be described as speeding up the higher frequencies at the  trailing edge of the pulse relative to the lower frequencies at the leading edge so as to compress  the pulse to a width 1/ B, where B = f2 -/1 (Fig. 11.15d). 
 COORDINATE MEASUREMENT OF THE RADAR TYPICALLY  WITH HIGH 3.2   IT CAN  BE WITHIN A FEW METERS AT HUNDREDS 
 Proc.IEEE.vol.53.p.1125,August, 1965. 95.Flock.W.L.:Monitoring BirdMovements byRadar,IEEESpectruIII. vol.5,pp.62-66.June.1968. 
 The Fourier split-step method is used to the PWE to solve the second-order derivative terms in Equation ( 16). Then, we derive the complex amplitude for the SAR signal as follow U(ρ⊥,z)=U(ρ⊥,0)·T(ρ⊥) (16) T(ρ⊥)=F−1/braceleftbigg exp/bracketleftbigg j/parenleftbiggκ2·z 2k0secθ/parenrightbigg/bracketrightbigg ·F/braceleftBig ejφ(ρ⊥)/bracerightBig/bracerightbigg (17) where κ=/parenleftbig κx,κy/parenrightbig is the transverse wavenumber. The spherical wave propagation is considered in the simulator by scaling the horizontal coordinate and the propagation distance with the factor z=z1z2/slashbig(z1+z2), where z1is the distance between the radar platform and the ionospheric height, z2is the ionospheric height, secθis applied to convert the vertical distance to the oblique distance. 
 Proceedings International Radar Conference IEEE Radar 05, pp. 435  – 440, Arlington, VA, USA, May 2005   − K. Schuler, M. 
 These short dwell time AR spectra may then be used to  estimate weather spectral moments the same as the Fourier data model spectrum esti - mators from which the weather parameters are derived.87 Processor Implementations.  Modern meteorological radars use digital signal  processing techniques on programmable platforms and interactive color displays  ch19.indd   24 12/20/07   5:39:06 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 In these roles, the emphasis is on fidelity. In HF skywave radar systems, modeling has  ch20.indd   55 12/21/07   10:44:32 AMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The pilot completes the interception bykeeping the spot centered onhisscope, and closing the range until the wings of thespot have grown tothedesired size. 6.14. Precision Tracking ofaSingle Target. 
 AMBIGUOUS CLUTTER RETURNS  AS MIGHT OCCUR DURING PERIODS OF ANOMALOUS PROPAGATION 4HE RETURNS RECEIVED DURING ONE #0) ARE PROCESSED IN THE BANK OF  . 
 157 175. December. 1957. 
 The complexity of the main steps of the basic MAM method. Main Step Operation Complexity SI: Achieving three sub-view images FFT 15 Nalog2Na SII: Estimating ˆedrand ˆe3rdFFT 30 Nalog2Na Complex conjugate multiplication 21 Na IFFT 15 Nalog2Na Modulus 27 Na Scom: Total 15 Nalog2Na+30Nalog2Na+21Na+15Nalog2Na+27Na T able 3. The complexity of the main steps of the improved MAM (IMAM) method. 
 175, pp. 681-682, 1955. 19. 
 The other term depends on both the amplitude  error and the phase error as well as the fraction of elements remaining operative. It also  depends on the aperture illumination, as given by the currents i,, . Note that this second term  is independent of the angular coordinates 8, #. 
 WhentheditTerence patternofamonopulse antenna canbeselectedindependent Iyofthe sumpattern, asinaphasedarray,thecriterion foragooddifrerence patternistoobtain maximum anglesensitivity commensurate withagivensidelobe level.Bayliss8!1txlsdescribed amethod forobtaining suitable monopulse difference patterns onthisbasis.Itparallels Taylor's approach tothesumpattern. 7.7COSECANT-SQUARED ANTENNA PATfERN ItwasshowninSec.2.11thatasearchradarwithanantenna patternproportional tocsclO, where8istheelevation angle,produces aconstant echo-signal powerforatargetllyingat constant altitude, ifcertainassumptions aresatisfied. Manyfan-beam air-sea~ch radars employthistypeofpattern. 
 Howard. D. D.: Single Aperture Monopulse Radar Multi-Mode Antenna Feed and Homing Device,  Proc 1964 fnternational Conv. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI.  AIRBORNE MTI  3.156x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 In order to treat scanning motion in the frequency domain, the apparent clutter  velocity seen by the scanning antenna is examined to determine the doppler frequency. 
 V., and S. F. George: Detection of Targets in Non-Gaussian Sea Clutter, IEEE Trans.,  vol. 
 PULSE BINOMIAL WEIGHT CANCELER  AND A  PULSE 
 It determines the incoming waves ah & av and the outgoing waves bh & bv, whereby h  and v respectively symbolize horizontal and vertical  polarization.  The correct scattering m a- trix [Sc] can consequently not be directly determined.  The matrix is measured [ Sm], which  additionally to [Sc] still considers the transmission and receiving paths Tξη & Rξη, as well as  the direct isolation Iξη. 
 Key passband characteristics are: insertion loss, bandwidth, passband amplitude  and phase ripple, and group delay. Bandwidths are frequently specified in terms of  a 3 dB bandwidth; however, if a low passband variation is required, the specified  ch06.indd   26 12/17/07   2:03:25 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 SITE REGION WAS DEVELOPED BY THE 5NIVERSITY OF 7ASHINGTON #ALLED THE -ANASTASH 2IDGE 2ADAR -22   IT IS DESIGNED TO STUDY TURBULENCE IN THE IONO 
 The co-ordinates of the  map are easy to appreciate. Horizontally is azimuth—  say, 90 degrees either way of the central point. Vertically  the radar ‘graph’ shows range up to, say, 25 miles. 
 RO.Dolph.C.L:ACurrcnt Distrihution forBroadside' ArraysWhichOptimizes theRelationship hetween Bcamwidth andSideLoneLevel.I'roc.IRE.vol.34.pp.335-348. Junc.1946;alsodiscus­ sionbyII.J.Rinlet,vol.35.pp.489-492. RI.Drane.C.J.:Dolph-Chehyshcv Excitation Coefficient Approximation. 
 Radio emission physics in the Crab pulsar. J. Plazma Phys. 
 Group 1 Group 2 Group 3 Poker Flat ISR 1.484 5.700 7.365 PolSAR (300 km) 1.514 (0.324) 4.646 (0.444) 6.812 (0.351)PolSAR (400 km) 1.586 (0.340) 4.864 (0.465) 7.112 (0.367) PolSAR (500 km) 1.660 (0.355) 5.092 (0.487) 7.434 (0.384) Deviation (400 km) 0.102 0.836 0.253 Poker Flat ISR (average) 1.46 5.71 7.86 GNSS 6 12.5 10.7 From Table 3, some phenomena are observed. First, the standard deviation of TEC in each PolSAR scene is small. This feature demonstrates that no strong variation occurred in the ionosphere during the observations. 
 A crystal diode which is subjected to excessive RF power may suffer brrrnour.  This is a rather loosely defined term which is applied to any irreversible deterioration in the  detection or conversion properties of a crystal diode as the result of electrical overload. If  excessive RF energy is applied to the diode the heat generated cannot be dissipated properly  and the diode can be damaged. 
 LOSOPHY  AS WELL AS THE HARDWARE  IS USUALLY DEPENDENT ON THE TARGET TYPE AND THE MATE 
 Cent. South Univ. 2013 ,20, 2498–2509. 
 02& RADAR  THERE IS LITTLE IF ANY RANGE REGION CLEAR OF SIDELOBE CLUTTER  SUCH THAT THE SIDELOBE  CLUTTER PORTION OF THE DOP 
 25.17  Forward-Scatter RCS Region  .............................  25.17  25.8 Clutter  .....................................................................  25.18  In-Plane Land Clutter Scatte ring Coefficient  ....... 
 This value of signal-to- noise ratio ( S/N)1 is that required if only one pulse is present. It has to be large enough  to obtain the required probability of false alarm (due to noise crossing the receiver  threshold) and the required probability of detection (as can be found in various radar  texts3,4). Radars, however, generally process more than one pulse before making a  detection decision. 
   42!#+).' 2!$!2   °ÎÎ !LTHOUGH THE RMS VALUE OF ANGLE NOISE IS ESSENTIALLY A CONSTANT FOR A GIVEN TARGET AND  ASPECT  THE SPECTRAL DISTRIBUTION OF THIS ENERGY IS DEPENDENT ON RADAR FREQUENCY AND THE  RANDOM TARGET MOTION ! TYPICAL SPECTRUM SHAPE IS   .F" "F    SPANG     WHERE . F    SPECTRAL NOISE POWER DENSITY  POWER(Z  "   NOISE BANDWIDTH  (Z  F   FREQUENCY  (Z 4HE VALUES OF  " ARE PROPORTIONAL TO RADAR FREQUENCY AND DEPENDENT UPON AIR TUR 
 ;= 
 Inthe double-threshold detector theycontribute thesameasanythreshold-crossing signalnomatter whattheiramplitude. Ananalysis oftheproblem ofdetection ofsignalsinclutter(ornoise) thatisnongaussian, indicates thatadetector basedonthemedianvaluecrossing athreshold is significantly moreefficient thantheusualdetection criterion basedontheme(lIIvalue.61The implementation ofthebinarymoving window detector issimilartothatofthemedian detector. Anestimate ofthetarget'sangular position maybemadebylocating thecenterofthe groupof11pulses.56Thisoperation iscalledbeamsplitting. 
 If a is not a constant over  the path R, the total attenuation must be expressed as the integrated value over the two-way  path. .J  Scattering from rain. Equation (13.18), which applies for Rayleigh scattering, may be used as a  basis for measuring with radar the sum of the sixth power of the raindrop diameters in a unit  volume. 
 The expected result is that the ﬁrst left singular vector should closely be related to the doppler history of the SAR system. As in Ethe transformed vectors are independent, the mostly correlated information in the signals in the columns of Xis stored in the ﬁrst singular vector in E, while the remaining part is in the others. Also, accordingly to the SVD decomposition scheme, the right singular vectors contain the mixing coefﬁcients able to orthogonalize the raw data matrix. 
 D. Potter, “Application of spherical wave theory to Cassegrainian-fed paraboloids,” IEEE  Trans ., vol. AP-15, pp. 
 Szondy, D. How to Navigate Deep Space by Pulsar 2016. Available online: https://newatlas.com/pulsars-gps- space-navigation /44978/(accessed on 30 November 2017). 
 The beam intercep-  tion on tile coritrol grid of practical nonintercepting gridded guns might be less than a few  lli~ridredtlis of one percent of beam current.' The shadow grid can also be used in the  traveling-wave tube.  Bandwidth. The frequency of a klystron is determined by the resonant cavities. 
 EDGE OR MULTIGATE RANGE TRACKING SHOULD BE AN EFFECTIVE %##- TECHNIQUE AGAINST CROSS 
 ING ALGORITHM  OFTEN USED IS THE ADJACENT 
 Thetwo cavities arcfedhytheseunemicrowave sourcewhichissweptinfrequency. Themeasured difference intheresonant frequencies ofthetwocavities isduetothedifferent dielectric properties (orindexofrefraction) ofthegaseswithinthetwocavities. Thisfrequency difference canbecalibfilted intermsoftheindexofrefraction oftheatmosphere inthesampling cavity. 
 Suppose that ther-f signal pulse consists ofawave train with arectan- gular envelope, ofduration rseconds. The re- sponse ofanamplifier (orfilter) tosuch apulse depends onthe width ofitspass band, which is ineffect aninverse measure ofthetime ofresponse oftheamplifier. Ifthis response time, inorder of magnitude 1/63, isvery much longer than T,the peak output signal power will beproportional to the square ofthe bandwidth @’. 
 However, the spacing, and therefore the  index of refractio11. cannot be made arbitrarily small since the reflection from the interface  between the lens and air will increase just as in the case of the solid-dielectric lenses. For a  value of s = ,1./2. 
 Heidrich; S. Riegger; W. Wiesbeck, "The signal flow error cube for pola rimetric  antenna and RCS measurements," in Proc. 
 Balanced duplexers. Thebalanced duplexer, Fig.9.6,isbasedontheshort-slot hybridjunction whichconsistsoftwosections ofwaveguides joinedalongoneoftheirnarrowwallswithaslot cutinthecommon narrowwalltoprovidecoupling between thetwO.3MTheshort-slot hybrid Antenna Figure9.5Principle ofbranch-lype duplexer.TransmitterI-------,---+--'t---.-----+-_--------,. '. 
 2.1I.—Lobes caused byinterference transmitter and target, theinterfer-ondirect andreflected wares.ence must affect the return ofthe radar echo inthesame degree asitaffects thepulse transmission. There- fore therequired modification oftheradar equation isobtained bymulti- plying byF’theexpression given inEq. (3)forthereceived signal po~ver S;that is, ()ll=P~,16sin4 * (29) To discuss the practical consequences ofthis wefirst distinguis!l between the problems of“high coverage” and “low coverage, ”In the former case weare concerned with targets sohigh orsoclose that 2rh,hZ/kR >1;that is,with targets lying well upin,orabove, the lowest lobe ofFig. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas.  REFLECTOR ANTENNAS  12.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 Multiple-Reflector Antennas.20–30 There are both difficulties and advantages  associated with adding a secondary, or subreflector, to a paraboloidal reflector system. 
 dar system are to be determined. Even with the use of the Shuttle to reduce the cost per pound of payload into orbit, large investment costs are expected to be required for the SBR system. 22.3 SBRSYSTEMDESCRIPTIONS The United States and the U.S.S.R. 
 38 Space-based deployable L-band ASTROMesh reflector with 12.25 meter  circular projected aperture ( Courtesy Northrop Grumman Corporation ) ch12.indd   38 12/17/07   2:32:00 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 
 TO 
 There was then no radio valve which could  produce such high-frequency oscillations.  Professor M. L. 
 BIT METHODv WAS BASED ON A "LOCK 
  TO  
 Of these adjustments, the most important (after the  attitude/sea-state correction) is the temperature correc­ tion. The receiver gain varies about 4 decibels over the  nominal temperature range and measurement repeata­ bility to better than 0.2 decibel is desired. A second-order  polynomial was derived from ground test data collected  during thermal/vacuum testing to relate gain control  changes to the observed receiver temperature. 
 Repeated signals have avery objectionable tendency to“burn in,” becoming stronger than transient signals and remaining on thetube long ,after theradar echo that created them has moved away or disappeared. This difficulty can beconsiderably alleviated byocca- sionally raising thetube temperature and scanning thescreen with aweak electron beam, both ofwhich measures tend tobleach the screen. A fairly intense burned-in pattern can thus beremoved inone ortwo minutes. 
 The feedback connections that provide the maximal-length sequences may be  determined from a study of primitive and irreducible polynomials. An extensive list of  these polynomials is given by Peterson and Weldon.27  Although maximal-length sequences have some desirable autocorrelation char - acteristics, a maximum length sequence does not guarantee lowest time sidelobes  when compared to other binary codes. An example of this is provided for a 15-bit  sequence. 
 J. aufm Kampe, “Physical properties of cumulus clouds,” J. Meteorol .,  vol. 
 Prac~ically, it-is preferable toemploy conventional salient-pole rotating-field synchronous alter- nators designed for400 cps, rather than high-impedance inductor alter- nators operating athigher frequencies. Although the reactance ofan inductor alternator canbeneutralized byaseries capacitance (asisdone in theModel 800-1-C Bendix 800-cps motor-alternator) such balance iscom- pletely effective only atone value ofaload exhibiting fixed power factor. Changes inload cause changes inwave shape. 
 Wiesbeck, "Planar microwave doppler -sensors for car  speed monitoring", Proc. of the 21st Europ. Microwave Conference, EuMC, pp. 
 Lynch, “System for Addressing and Address Incrementing of Arithmetic Unit  Sequence Control System,” U.S. Patent 4,075,688, 2/21/1978.  6. 
 . Radar System Engineering  Chapter 10 – Characteristics of Radar Target s 96     ahbh avbvEhs Evs Ehi EviReceive Path Transmit PathCoherent  Multifrequency  Transmit/Receive  SystemScattering  ObjectDirect CouplingSm 1234 5 cS   Figure 11.6  Schematic block diagram of a polarimetric RCS measurement system.   There are two distinguishable error categories with measurement systems: systematic errors  and statistical errors. 
 VIEWING  RADAR ALTIMETER 0RINCIPAL FEEDBACK LOOPS INCLUDE RANGE 
 58. Morgan. S. 
  &)2 FILTER 4HE &)2 FILTER CAN BE TAILORED TO REMOVE THE UNDESIRED RESIDUAL COMPONENTS BEFORE THE FINAL DECIMATION 4HE &)2 FILTER CAN ALSO BE CONFIGURED TO COMPENSATE FOR THE DROOP IN THE PASSBAND RESPONSE &IGURE  SHOWS AN EQUIVALENT FORM FOR A #)# DECIMATION FILTER  WHERE THE DECI 
 £Ó°Ón  2!$!2 (!.$"//+  !RRAY &EEDS ! SINGLE FEED AT THE FOCAL POINT OF A PARABOLA FORMS A BEAM PARALLEL  TO THE FOCAL AXIS !DDITIONAL FEEDS DISPLACED FROM THE FOCAL POINT FORM ADDITIONAL BEAMS  AT ANGLES FROM THE AXIS SEE %Q   4HUS  ONE CAN EMPLOY A MULTIPLE FEED ARRAY WITH APPROPRIATE ELECTRONICS TO FEED A REFLECTOR AND PROVIDE EITHER MULTIPLE DISPLACED BEAMS OR ELECTRONIC BEAM SWITCHING  IE  BEAM SCANNING TO DISCRETE ANGLES ! REFLECTOR SYSTEM SUCH AS THIS CAN EFFECTIVELY PROVIDE ELECTRONIC SCANNING OVER A NARROW &/6 (OWEVER  THIS TYPE OF ARRAY 
 The homogeneous single-layer radome has been used in many  radome applications. Materials for this type have included fiberglass-reinforced plas - tics, ceramics, elastomers, and monolithic foam. The optimum thickness for a single  layer is a multiple of a half wavelength in the dielectric material at the appropriate  incidence angle, but many single-layer radomes are simply thin-wall approximations  to the zero-thickness case. 
 but tl~is is nri irielficier~t rliettioci for elitiiiriating the~ii. It is niore convenierit to  eliriiir~i~te theni iri the ratl:ir sigr~itl-processor by either analog hiilk-processi~~y or its special-  ~~rrr.~~osc tligiti~l cclrriv;~lcrit. St1c11 sipr~:~l ~~roccssirig ir~cltrcles ~natctletl filterit~g, cloppler (M-1'1)  filtcri~~g. 
 295 Yuhang Wang, Min Yang and Jinsong Chong Simulation and Analysis of SAR Images of Oceanic Shear-Wave-Generated EddiesReprinted from: Sensors 2019 ,19, 1529, doi:10.3390/s19071529 .................... 311 vi. About the Special Issue Editor Fabio Bovenga (Ph.D.): Fabio Bovenga received the Laurea degree and the Ph.D. 
 Oneothermethod shouldbementioned ofachieving coherent MTI.Ifthenumber of cyclesofthedoppler frequency shiftcontained withintheduration ofasinglepulseis sufficient, thereturned echoesfrommovingtargetsmaybeseparated fromclutterbysuitable RForIFfilters.Thisispossible ifthedoppler frequency shiftisatleastcomparable withor greaterthanthespectral widthofthetransmitted signal.Itisnotusuallyapplicable toaircrafl targets,butitcansometimes beappliedtoradarsdesigned todetectextraterrestrial targets suchassatellites orastronomical bodies.Inthesecases,thetransmitted pulsewidthisrela­ tivelywideanditsspectrum isnarrow.Thehighspeedofextraterrestrial targetsresultsin doppler shiftsthatareusuallysignificantly greaterthanthespectral widthofthetransmitted signal. 4.11MTIFROMAMOVING PLATFORM Whentheradaritselfisinmotion, aswhenmounted onashiporanaircraft, thedetection ofa movingtargetintheprescnce ofclutterismoredifficultthaniftheradarwerestationary. The doppler frequency shiftoftheclutterisnolongeratdc.Itvarieswiththespeedoftheradar platform, thedirection oftheantenna inazimuth, andtheel.evation angletotheclutter.Thlls theclutterrejection notchneededtocancelcluttercannotbefixed,butmustvary.Thedesign ofanMTIismoredifficult withanairborne radarthanashipborne radarbecause thehigher speedsandthegreaterrangeofelevation anglesresultinagreatervariation oftheclutter spectrum. 
 24.10, ( ⋅)H stands for the com - plex conjugate transpose operation. The amplitude b can be separately estimated by  nulling the first derivative of the function to be minimized. By replacing the ampli - tude estimationˆbinto the function to be minimized, the following DoA estimator  is obtained:   (ˆ,ˆ) { ( ,)}S ( , , , θ φ θ φθ φ θ φ θ φ T TH U = = argmax argmax) ) S ( , ) S(, )i i i iM V Md H d− −   12 1θ φ θ φ   (24.11) It can be noted that the numerator of the functional U( q, f) is the squared adapted  output (|( ,) | ) SH d θ φi iM V−1 2 of a generalized array of high and low gain antenna  patterns; the denominator [ ( , ) ( ,)] S MH dS θ φ θ φ i i−1 is a normalizing term that, as we  will see in a moment, plays a key role. 
 For example, to replace the old, well- proven 5J26 L-band magnetron that develops 500 W of average RF power at 0.1 percent (typical) duty cycle would require 2500 to 5000 of the 50-W transistors just mentioned. In other words, microwave transistors are much more cost- effective when the required radar system average power can be provided by a lower peak power at a higher duty cycle. As a result, there have been relatively few direct replacements of older low-duty-cycle transmitters by solid-state trans- mitters; the AN/SPS-40 is an interesting exception to this rule and will be dis- cussed later. 
 Serafin and J. W. Wilson, “Operational weather radar in the United States: Progress and  opportunity,” Bull. 
 TIES  FERRITE PHASE SHIFTERS ARE ALMOST NEVER USED AT FREQUENCIES BELOW  '(Z $IODE PHASE SHIFTERS  IN CONTRAST  IMPROVE AS THE FREQUENCY GETS LOWER 4HERE ARE THREE BASIC TYPES OF PHASE SHIFTERS THAT TYPICALLY COMPETE FOR USE IN A  PHASED ARRAY 4HEY ARE   THE DIODE PHASE SHIFTER    THE NONRECIPROCAL FERRITE PHASE SHIFTER  AND   THE RECIPROCAL DUAL 
 range, is approximately:   € ΔR≈c0τ 2 (10.1)   Then orthogonal to that in azimuth, i.e. cross range, is given with the  half- power bandwidth:  € Δz≈θ3dB⋅R; θ3dB≈68°⋅λ a for cos2-taper         (10.2)  Presently it is assumed that two targets can be separated if their echoes overlap at the 3 dB  points (half power).  With various new algorithms an increased resolution can be achieved. 
 PHASE CONDITIONS )F THE BACKGROUND SIGNAL IS EQUAL TO THE TARGET SIGNAL RATIO OF  D"  AND THE TWO ARE IN PHASE  THE TOTAL RECEIVED POWER IS FOUR TIMES THE POWER DUE TO EITHER ONE 4HIS IS THE VALUE SHOWN AT THE UPPER LEFT OF THE CHART  D"  )F THE TWO ARE OUT OF PHASE  THEY CANCEL EACH OTHER  AND THERE IS NO SIGNAL AT ALL OFF THE LOWER LEFT OF  &)'52%   4HE FAR 
 3  53. Ksienski, A. A., Y. 
 Such stations include the Arecibo Observatory  and the NASA Deep Space Network. Subsequent measurements were made using  Lunar Orbiter-1 , Explorer-35 , and Apollo 14–16 . Mars bistatic radar measurements  were made using Mariner-6 , -7, Viking-1 , -2, Mars Global Surveyor , and Mars  Express . 
 FREQUENCY CONVERTERS ARE SYNCHRONIZED TO A MULTIPLE OF THE 02&  IN WHICH CASE F DOP    !SSUME THAT THE NOISE 
 MITTER BEAM 4HIS MAY BE OBTAINED EFFICIENTLY FROM THE SAME ANTENNA WITH A GABLED OR SPHERICAL PHASE DISTRIBUTION 7ITH IDENTICAL SUBARRAYS  A DESIRED APERTURE AMPLITUDE TAPER FOR LOW SIDELOBES  IS  APPLIED WITH A GRANULARITY THAT DEPENDS ON THEIR SIZE AND SHAPE 4HE RESULTING AMPLI 
 Pleasure craft systems typically have peak powers of 2 – 4 kW and  utilize antennas with horizontal apertures as small as 450 mm and gains of about 24 dB.  These all operate at 9 GHz. The greatest technical challenge in designing marine radars  is to maintain good target detection in high levels of sea and precipitation clutter. 
 The smearing of the moving pointlike target is evident. Given the motion param - eters, the target has migrated over six range cells. This is the cause for the broaden - ing of the target image even in range, as well as in cross range. 
 The propagation code is due to Berry FD j~G V ^X FIG. 24.29 Examples of a target T are shown when approaching (right) and receding (left) in the presence of the sea echo. The for- mat is of received power versus normalized doppler for seven ra- dar operating frequencies. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar.  BISTATIC RADAR  23.216x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 large discrete scattering centers, for example, through shadowing, target glint is often  reduced. 
 8. Hofmeister, E. L., et al.: GOES-C Radar Altimeter, vol. 
 ANTENNA GAIN OF THE 272  K  IS THE RADAR WAVELENGTH THE QUANTITY  K4S" IS THE TOTAL SYSTEM NOISE POWER OF THE 272  AND , IS THE LOSSES.   %,%#42/.)# #/5.4%2 
 Conv. Record, vol. 3, pt. 
 '(Z AIRBORNE CLOUD RADAR  FOR THE $# 
 10.1] CONSTRUCTION 323 later resides mainly inthe circular hole, and the capacitance mainly between theparallel plane surfaces oftheslot. The dimensions ofthese cavities determine toalarge degree the oscillation frequency ofthe magnetron. Since thefrequency isafunction oftheproduct LC,thesame frequency can beobtained from avariety ofshapes which have the. 
 SURFACE 'REENS &UNCTION  METHOD FOR COMPUTING  TRANSMISSION LOSSES IN AN INHOMOGENEOUS ATMOSPHERE OVER IRREGULAR TERRAIN v  )%%% 4RANSACTIONS  ON !NTENNAS AND 0ROPAGATION  VOL  NO  P n  2 " 2OSE  h!DVANCED PROPHET (& ASSESSMENT SYSTEM v .AVAL  /CEAN 3YSTEMS #ENTER  3AN $IEGO   *ANUARY   2 % $ANIEL  *R  , $ "ROWN  $ . !NDERSON  - 7 &OX  0 ( $OHERTY  $ 4 $ECKER  * * 3OJKA   AND 2 7 3CHUNK  h0ARAMETERIZED IONOSPHERIC MODEL ! GLOBAL IONOSPHERIC PARAMETERIZATION  BASED ON FIRST PRINCIPAL MODELS v 2ADIO 3CIENCE  VOL   PP n    + 2AWER  3 2AMAKRISHNAN  AND $ "ILITZA  h)NTERNATIONAL REFERENCE IONOSPHERE  v  )NTERNATIONAL 5NION OF 2ADIO 3CIENCE  523) 3PECIAL 2EPORT  PP   "RUXELLES  "ELGIUM    h0ROPAGATION IN .ON 
 Air surveillance radars can be of long range at S band, but long range usually is more difficult to achieve than at lower frequencies. The blind speeds that occur with MTI radar are more numerous as the frequency increases, thus making MTI less capable. The echo from rain can significantly reduce the range of S-band radars. 
 andA.D.Rosenherg: VeryHighFrl:qul:ncy Radiowave Scattering byaDisturbed SeaSurace.IEEETrails..vol.AP-16.pp.554·568. Septl:lllhl:r. 196H. 
 Any use is subject to the Terms of Use as given at the website. Radar Digital Signal Processing. 25.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 Since additions are performed in each stage, the magnitude of each output stage  sample could be a factor of two or more greater than the input samples. If fixed-point  computations are used, then this increased dynamic range results in a growth in the  number of bits required to represent the values, and there needs to be a strategy to  accommodate it. 
 1904  The German high frequency engineer Christian Hülsmeyer  invents the  “Telemobiloskop ” to the traffic supervision on the water. He measures the running  time of electro -magnetic waves to a metal object (ship) and back. A calculation of  the distance is thus possible. 
 PLANE PLOT OF FAR 
 The scattering direction in backscattering problems is the reverse  of the direction of incidence, whence the diffraction cone becomes a disk, and the scat - tering edge element is perpendicular to the line of sight. The amplitude of the diffracted field is given by the product of a diffraction coeffi - cient  and a divergence factor , and the phase depends on the phase of the edge excitation  and on the distance between the observation point and the diffracting edge element.  Two cases are recognized, depending on whether the incident field is polarized parallel  or perpendicular to the edge. 
 5.18 Block diagram of the NAVSPASUR transmitter amplifier module.Gain/loss (dB) -0.60 -0.03 + 9.2 -0.06(-0.2) -0.10 -020 -0.30 + 9.70 -05 Power (watts) 300 344 (4x94) 11.5 52 5.7 62 . FIG. 5.19 RAMP transmitter amplifier module. 
 T. M.: Solid-state Radar, Chap. 30 of" Radar Handbook," M. 
 Radar Conf ., Paris, 1978, pp. 222–231. 19. 
 Schwartnnan. L., and P. M. 
 Asuitable site should belevel within afew feet forahalf-mile radius around theradar. Even seareflection can betroublesome, because tides cause aprofound change inthe calibration ofthestation asaheight finder. For these reasons, a free-space-beam height finder, not depending onground reflection, is usually preferred. 
 Figure 13. The correlation between subsidence rate and impervious surface fraction. In this city, soft soils or carbonate rocks are widespread, but only these areas with intensive human activities show severe subsidence, so natural conditions provide a basis for subsidence and make subsidence possible. 
 This was achieved by the 20 μs priming pulse from the modulator being applied after suitable ampli ﬁcation to their screen grids. The IF signals were detected with a valve diode (VR92). The video was ampli ﬁed and then mixed with the course marker and range marker. 
 Nurl. B~tr.. Srurrdirrds (U.S.) J. 
 In principle, target tracking could be aided by data from AIS (Section 22.7).  However, AIS data is best left out of the radar tracking process in order to keep them  entirely independent. Once radar tracks have been formed, they can then be auto - matically compared to AIS data and associated into a single track, if desired by the  operator. 
 Reprinted with permission from  AT&T Technical Journal.) FIGURE 14.9  Coordinate system for the RCS patterns in  Figure 14.8. ( S. S. 
 Typical radar values of the  MDS echo lie in the range of -104 dBm to  -113 dBm.       Noise   The value of the MDS echo depends on t he Signal -to-Noise -Ratio, defined as the ratio of the signal  energy to the noise energy. All radars, as with all electronic equipment, must operate in the  presence of noise. 
 The bistatic radar is not a new concept. Its principle was known and  demonstrated many years before the development of practical monostatic radar. In Sec. 
 Performance ofrotating equipment must beconsidered, aswell as that oftransformers. For stable performance and minimum weight ofalternators and a-cmotors, 400 cps ispreferable to800 cps. (See Sec. 
 SION HAS NOT BEEN AS POPULAR AS THE AMPLIFIER FOR RADAR APPLICATIONS 4HIS MIGHT BE DUE TO THE AMPLIFIER BEING BETTER ABLE TO PRODUCE THE DESIRED RADAR WAVEFORMS £ä°ÈÊ /, - // 
 (Not generally available.)  9. Slepian, D.: Estimation of Signal Parameters in the Presence of Noise, I RE Trans., no. PGIT-3, pp. 
 C.  Hansen (ed.), Academic Press, New York, 1966, chap. I. 
 S. Symons, “Tubes: Still vital after all these years,” IEEE Spectrum , vol. 35, pp. 
 EN V   BSX XPONENTIALSPECTRUM    !SSUMING  A VALUE OF  SV  MS  CORRESPONDING TO WINDY CONDITION  THE THREE 
 He obtained a patent in 1904 in several countries for an  obstacle detector and ship navigational device.2 His methods were demonstrated before the  German Navy, but generated little interest. The state of technology at that time was not  sufficiently adequate to obtain ranges of more than about a mile, and his detection technique  was dismissed on the grounds that it was little better than a visual observer.  Marconi recognized the potentialities of short waves for radio detection and strongly  urged their use in 1922 for this application. 
 PASS )N3!2  OR BY THE SAME PLATFORM  MAKING TWO PASSES OVER THE SAME TERRAIN  TWO 
 OF 
 (4.36 ).] If the mean doppler-frequency shift of the clutter echo is perfectly com­ pensated, the limitations on the improvement factor due to clutter spread can be found by  assuming a gaussian spectral shape and substituting the standard deviation of Eq. (4.37) into  the expression of Eq. (4.27) to obtain  I pm = (; ( l.~n ~~~jJ 2N1 (4.38)  where N1 is the number of delay lines in the MTI processor. 
 Moran, and D. C. Welsh: The Precision and Relative Accuracy of Profiler Wind Measure- ments, J. 
 A. R. Domville, “The bistatic reflection from land and sea of X-band radio waves, Part I,” GEC  (Electronics) Ltd., Stanmore, England, Memorandum SLM1802, July 1967. 
 LENGTH OF THE RADIATION AND THE PHYSICAL DIMENSIONS OF THE TARGET )N MOST CASES FOR '02  THE RATIO IS CLOSE TO UNITY 4HIS COMPARES VERY DIFFERENTLY WITH AN OPTICAL IMAGE  WHICH IS OBTAINED WITH WAVELENGTHS SUCH THAT THE RATIO IS CONSIDERABLY GREATER THAN UNITY TYPICALLY    )N '02 APPLICATIONS  THE EFFECT OF COMBINATIONS OF SCAT 
 Cllittcrreductioll. Ashortpulseincreases thetarget-to-clutter ratiobyreducing theclutter contained withintheresolution cellwithwhichthetargetcompetes. Glilltreduction. 
 7.8). If an adder is located at each element, the row-and-column values mTxs and nTys may be summed at the element. It is also possible to put two phase shifters in series so that the summation can be done at microwave frequencies. 
 H. Tabeling: Tracking Instrumentation and Accuracy on the Eastern Test Range, IEEE Trans., vol. SET-Il, pp. 
 'I'lie effective baridwidtll of a waveforti1 with a uniform frequency spectrutn of width U is  /I = n~/ Jj. The wavefortli which gives rise to a uniform frequency spectrum is of the forni  (sill .x)/.u, wtiere .u = nllr. The rrns time-delay error is therefore  J3 67' - sin x  - rt B(~E/N~)"~ - waveform  X  The radar waveforni which yields the most accurate time-delay measurement, all other  factors being equal, is the one with tlie largest value ofeffective bandwidth 0. 
 ERROR 
 DIFFERENCE DOPPLER FREQUENCY ESTIMATOR FOR DIFFERENT  WEIGHTING FUNCTIONS OF THE DOPPLER FILTER BANK     
 J. Sullivan, A. D. 
 IBIS-ArcSAR: an Innovative Ground-Based SAR System for Slope Monitoring. In Proceedings of the IGARSS 2018 IEEE International Geoscience and Remote Sensing Symposium, Valencia, Spain, 23–27 July 2018; pp. 1348–1351. 
 PEDESTAL WEIGHTING &OR A GIVEN PEAK TIME SIDELOBE LEVEL  4AYLOR  WEIGHTING OFFERS THEORETICAL ADVANTAGES IN RANGE RESOLUTION AND 3.2 PERFORMANCE  AS ILLUSTRATED IN &IGURE B AND &IGURE C &)'52%    A  4APER COEFFICIENT AND PEDESTAL HEIGHT VERSUS PEAK TIME SIDELOBE  LEVEL B  #OMPRESSED 
 The result - ing vectors for near-surface winds cover 4–24 m/s with accuracy ± 2 m/s and ± 20°.  The radar operates at 5.255 GHz, radiating 10 ms linear frequency-modulated (LFM)  pulses at 120 W peak power from combined GaAs FET devices. Only one antenna is  active (for 0.2 s) at a time; the operation cycles around the six antennas in sequence. 
 Ifthe sethas beacon AFC, the radar-beacon switching relay should transfer the remote meter tothe beacon cavity crystal. Then asteady meter reading indicates not only that thebeacon AFC is locked, but that itislocked atthe correct frequency, since the crystal energy has come through thereference cavity. Ofthe test points usually provided forcover-off checking, the most essential isajack tomeasure thecrystal current atevery crystal, inorder topermit adjustment ofthe Iocal-oscillat orcoupling. 
 This dash starts a short distance beyond the  actual position of the AtoN because of inherent delays in the response time of the racon.  However, delays giving an error of less than 100 meters are readily achievable. In good  conditions, the AtoN primary radar image will be displayed on the radar screen, helped if  a passive radar reflector is also a part of the AtoN. 
 L  Figure 6.10 Pilotograph of the VA-87E 6-cavity S-band klystron mounted on a dolly. (Courtesy Varian  .Issociates. IIIC., Palo Alto, CA.)  beam voltage of 65 kV is required and its peak beam current is 34 amperes. 
 Microstrip is a quasi-TEM mode transmission-line medium that requires photolithographically defined lines on a low-loss, high-quality dielectric substrate. Reactive compo- nents that are necessary as impedance-matching elements can be approximated in the microstrip format. An inexpensive reactive matching network can be formed by using an interconnected pattern of microstrip elements. 
 In man yapplications this delay isnegligible, inothers itismade tohave a constant known value forwhich allowance can bemade. The delay can bekept down toafew tenths ofamicrosecond when necessary. Inthe special case where the radiated pulse issingle, has approximately the 243. 
 Doppler lolerance. Withasingleshortpulse,thedoppler frequency shiftwillbesmall compared tothereceiver bandwidth sothatonlyonematched-filter isneededfordetec­ tion.ratherthanabankofmatched filterswitheachfiltertunedforadifferent doppler shift. Ashort-pulse radarisnotwithoutitsdisadvantages. 
 The arrangement ofFig. 7.5permits the use ofonly one scale, but affords, asshown, the considerable advantage that awax pencil can be used forplotting theposition ofeach radar echo ofinterest, with amini- mum ofdifficulty from parallax. Asthe pencil point touches the edge- lighted plotting surface, itglows brightly over the small area ofcontact, and small corrections inthe position ofthe point can bemade before a mark isactually applied tothescreen. 
 It has been suggested that other forms of meteorological angels are the  mantle-shaped echoes (inverted U-or V-shape) associated with the upper surfaces of cu­ mulus clouds. and echoes believed to be produced by the boundary surfaces between differen­ tially moistened surface air over adjacent cold and warm water.113 Radar also can detect the  passage of an invisible sea breeze as it moves toward the shore.70·100 Occasionally radar  echoes may be obtained from large mineral or organic particles carried into the air by heavy  winds or thundcrstorms.100 Echoes have also been received from the vicinity of forest fires and  from the smoke plumes of dump fires.100 The reflectivity of smoke particles is too small to  account for these rcnections, but the echoes might be due to the numerous large particles and  debris sometimes present in the air above the fires. The heat from the fire also might cause . 
 10.3. Electron Orbits and the Space Charge.—An electron inthe interaction space ofamagnetron isacted onbyaconstant magnetic field parallel totheaxis ofthecathode, aconstant radial electric field resulting from the applied d-cpotential, and the varying electric field extending into theinteraction space from charges concentrated near theends ofthe. SEC. 
 VIB, ARI 5604 ASV Mk. VIB was intended for bulk production, replacing ASV Mk. VI and ASV Mk. 
 63. Frank, R. L.: Polyphase Codes with Good Nonperiodic Correlation Properties, IEEE Trans., vol  IT-9, pp. 
 26.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 For radar engineers, a display such as that shown in Figure 26.15 will most likely  not be very useful since propagation factor, Fp, is the desired quantity for the radar  range equation and not the propagation loss as computed by APM. However, there is a  simple relationship between propagation loss and propagation factor . This is  F L Lp= −fs dB (26.17) where  Lfs is the free-space propagation loss given by Eq. 
 Res. Lett. , vol. 
 Aerosp. Electron. Syst. 
 TO 
 Radant, M.E. The evolution of digital signal processing for airborne radar. IEEE T rans. 
 Any use is subject to the Terms of Use as given at the website. Radar Receivers.  RADAR RECEIVERS  6.496x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 Errors such as phase truncation and D/A converter quantization and nonlinearity  produce spurious signals due to their deterministic nature. The spurious signal fre - quencies generated by a DDS can be readily predicted16 as they are a function of the  digital architecture and programmed frequency. 
 In other radar units we find a  system of Azimuth -Change -Pulses (ACP). In every rotation of the antenna a coder sends many  pulses, these are then count ed in the scopes. Some radar sets work completely without or with a  partial mechanical motion. 
 TRANSFORM SOLUTIONS FOR CONTINUOUS APERTURES  MAY BE USED TO  APPROXIMATE PATTERNS FOR PRACTICAL AMPLITUDE AND PHASE DISTRIBUTIONS AS LONG AS THE  ELEMENT 
 Significant advances are evident in the digital and SAW techniques  that allow the implementation of a variety of pulse compression waveform types. The  digital approach has blossomed because of the manifold increase in computational  speed and also because of the size reduction and the speed increase of the memory  units. SAW technology has expanded because of the invention of the interdigital trans - ducer,45 which provides efficient transformation of an electrical signal into acoustic  energy and vice versa. 
 Chandrasekar, K. Droegemeier, S. Frasier, J. 
 Because ofthe close connection ofthe whole AFC problem with receiver design, consideration ofthis subject isdeferred toSec. 12.7. MOUNTING THE R-F PARTS Experience has demonstrated that good radar performance depends not only onawell-designed setofmicrowave components but also ona properly coordinated mounting ofthem, relative toeach other and rela- tive tothe other parts oftheradar. 
 The first exception to this rule  was RADARSAT-1, designed around an array of 32 horizontal slotted waveguides,  each of which was center-fed through a phase shifter so that the elevation beam pat - tern could be selected and shaped electronically. More ambitious (read “massive and  expensive”) systems tend to use two-dimensionally active electronic scanned arrays  (ESAs). These are populated by transmit/receive (T/R) modules, often incorporating  two polarizations (H and V). 
 150, pt. F, no. 1, pp. 
 vol. 35, pp. 1489-1498, Decem­ ber. 
  .IGHTHAWK  BY CONTRAST  ARE INSTALLED ABOVE THE WING AND WELL AFT OF THE LEADING EDGE THEY ARE THE LITTLE BLACK DIAMONDS SEEN IN  THE NOSE 
 \ .JFrequency agility and glint reduction. 35-4o,ss The angular error due to glint, which affects all  tracking radars, results from the radar receiving the vector sum of the echoes contributed by  the individual scattering centers of a complex target, and processing it as if it were the return  from a single scattering center. If the frequency is changed, the relative phases of the individual  c.. 
 87 to 2.91, 2.99 to 2.100 Sensor  integration, other than radar, 7.49 to 7.54 Senrad broadband radar, 24.31 Sequential lobing, 9.16 to 9.17 Servosystems, for tracking radar, 9.17 to 9.19 Shaped pulses for transmitter, 10.19 to 10.20 Shaped reflector antennas, 12.19 to 12.20.     I_15 Shaping, for radar cross-section reduction, 14.38 to 14.39 Ship, radar cross section, 14.13 to 14.15 Ships, low cross section, 14.42 to 14.43 Sidelooking airborne radar (SLAR), 1.6 17.3 Sidelobe blanking (SLB), 24.11 to 24.14 Sidelobe canceler, 24.14 to 24.20 Sigma zero (for clutter echo), 15.7, 16.1 to 16.3 Signal-to-clutter ratio improvement, 2.21 to 2.22 Signal-to-noise ratio, 1.9 in SAR, 17. 16 to 17.17 Signal processing, and ECCM, 24.33 to 24.36 Signal processing, for meteorological radar, 19. 
 TIME  SIGNAL PROCESSING 4HE REQUIRED OPERATIONS NEED TO BE SPLIT UP APPROPRIATELY AMONG THE AVAILABLE PROCESSORS  AND THE RESULTS NEED TO BE PROPERLY MERGED TO FORM THE FINAL RESULT ! MAJOR CHALLENGE IN THESE APPLICATIONS IS TO SUPPORT THE PROCESSING  LATENCY  REQUIREMENTS OF THE SYSTEM  WHICH DEFINES THE MAXIMUM LENGTH OF TIME ALLOWED TO PRODUCE A RESULT 4HE LATENCY OF A PROCESSOR IS DEFINED AS THE  AMOUNT OF TIME REQUIRED  TO OBSERVE THE EFFECT OF A CHANGE AT A PROCESSORS INPUT ON ITS OUTPUT !CHIEVING LATENCY GOALS OFTEN REQUIRES ASSIGNING SMALLER PIECES OF THE WORKLOAD TO INDIVIDUAL PROCESSORS  LEADING TO MORE PROCESSORS AND A MORE EXPENSIVE SYSTEM !NOTHER CHALLENGE FACING . 
 2a and b):  Wavelength  Power  Illuminated area  Direction of illumination (both azimuth and elevation)  Polarization (including the full polarization matrix when available) Ground parameters:  Complex permittivity (conductivity and permittivity)  Roughness of surface   Inhomogeneity of subsurface or cover to depth where attenuation reduces  waves to negligible amplitude ch16.indd   4 12/19/07   4:54:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 Results were also compared with other methods, showing improvements in presence of co-registration and perspective errors. 2.6. Sea Applications The last three papers [ 17–19] of the special issue present SAR imaging algorithms devoted to two sea applications, namely, ship detection and classiﬁcation, and oceanic eddy detection and analysis. 
 LOOKING ANTENNA 4HE CORRESPONDING LENGTH OF THE SYNTHETIC APERTURE IS EQUIVALENT TO THE ALONG 
 R. and B. /\. 
 Thisiscalledastaggered-prJ MTI.Operating atmorethanoneRF frequency canalsoreducetheeffectofblindspeeds.. 10 100  Maximum unombiguous range, nautical miles  Figure 4.8 Plot of MTI radar first blind speed as a function of maximum unambiguous range.  Double cancellation. 
 14.37  14.20 Personnel Detection Radar and Miscellaneous  FM-CW Systems  ....................................................  14.39  14.21 Tailoring the Range Response of FM-CW  Systems  ..................................................................  14.41 . 
 3CAN  PARTICULARLY  APPLICABLE TO %3! 
 This is accomplished by combining the sum and difference signals by some means so that they may be individually retrieved at the output. These techniques provide some advantages in AGC or other processing techniques but at the cost of SNR loss or of cross coupling between azimuth and elevation information. A single-channel monopulse system called SCAMP (single-channel monopulse processor)20 provides the desired constant angle error sensitivity by normalizing the difference signals with the sum signal in a single IF channel, as shown in Fig. 
 Hardy, and K. M. Glover: Applications of Radar to Meteorological Opera-  tions and Research, Proc. 
 It also meant that when changing range scales a few seconds would be neededfor the old display to fade and a new display to be established. As well as the radar returns, the PPI display could also show a line of ﬂight marker and an operator controlled range ring. For ASV operations, the PPI display was always orientated‘heading up ’.O nH 2S Mk. 
 Inatypicalduplexer application thetransmitter peakpowermightbeamegawatt or. 360 INTRODUCTION TO RADAR SYSTEMS  more and the maximum safe power that can be tolerated at the receiver might be less than a  watt. Therefore, the duplexer must provide, in this example, more than 60 dB of isolation  between the transmitter and receiver with only negligible loss of the desired signal. 
 Figure 5.6 Plot of the relative angle-  error signal from the conical-scan radar  as a function of target angle (eT/oB)  and squint angle (040,). 0, = half-  power beamwidth.  angle between the antenna-beam axis and the axis of rotation; and OB is the half-power  beamwidth. 
 Speckle Reducing Anisotropic Diffusion. IEEE T rans. Image Process. 
 The  effect of these techniques and the spurious signals that they are designed to mitigate  should be considered carefully as they may be detrimental to radar performance. The  use of dithering will randomize the spurious signal, resulting in pulse-to-pulse varia - tions in the digital sequence output to the D/A converter, a result that is undesirable in  pulse doppler applications. Truly random errors are not generated by the digital portion of the DDS. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°ÎÎ WAVEFORM IS A STEP FUNCTION  WHOSE RISE TIME IS EQUAL TO THE COMPRESSED PULSE LENGTH  AND WHOSE POSITION ON THE TIME 
 ALARM RATE AND A LOW TARGET DENSITY (OWEVER  ONE MAY REQUIRE A MUCH LARGER NUMBER OF DETECTIONS WHEN THE RADAR HAS THE FLEXIBILITY OF AN ELECTRONIC SCAN THAT CAN PLACE MANY DETECTION OPPORTUNITIES IN A SHORT TIME INTERVAL   "ACKWARD 
 ITY TO TRAP ENERGY IS HIGHLY DEPENDENT ON FREQUENCY 'ENERALLY  THE EVAPORATION DUCT IS  ONLY STRONG ENOUGH TO AFFECT ELECTROMAGNETIC SYSTEMS ABOVE  -(Z &OR SURFACE DUCTING CONDITIONS  THE  VERTICAL EXTENT OF THE DUCT IS SUFFICIENT TO ALLOW FOR  ITS MEASUREMENT USING AN ASCENDING RADIOSONDE  A DESCENDING ROCKETSONDE  OR A MICRO 
 In the sample images, there is an airplane visibly parked next to a building near the bottom center. It can be seen that many of the pixels in the 2CMV image are colored either red or cyan even if there is no change in the area. Useful interpretation of temporal changes represented in 2CMV AGI products can be challenging because of speckle noise susceptibility and false positives that result from small orientation differences Sensors 2019 ,19, 2605; doi:10.3390/s19112605 www.mdpi.com/journal/sensors 263. 
 Soderblom, “Magellan:  Radar performance and data products,” Science , vol. 252, pp. 260–265, 1991. 
 TO 
 The two mixers in Fig. 9.3 may be  single-ended, balanced, or double-balanced mixers. ' This mixer is capable of wide bandwidth,  and is restricted only by the frequency sensitivity of the structure of the microwave circuit. 
 DELAY SYSTEM IS SHOWN IN &IGURE  ! SINGLE 
 4.8LllVlITATIONS TOMTIPERFORMANCE Theimprovement insignal-to-clutter ratioofanMTIisaffected byfactorsotherthanthe designofthedoppler signalprocessor. Instabilities ofthetransmitter andreceiver, physical motions oftheclutter,thefinitetimeontarget(orscanning modulation), andlimiting inthe receiver canalldetractfromtheperformance ofanMTIradar.Beforediscussing theseeffects, somedefinitions willbestated. MTIil1lrrove111ellt factor.Thesignal-to-clutter ratioattheoutputoftheMTIsystemdivided hythesignal-to-c1utter ratioattheinput,averaged uniformly overalltargetradialveloci: tiesofinterest. 
 4.31.  A stepped-scan antenna that dwells at a particular region in space, rather than scan  continuously, also is limited in MTI performance by the finite time on target to. The rime  waveform is constant so that it will have a different spectral shape and a different improvement  factor than that produced by the gaussian beam assumed in the above. 
 A. S. Gilmour, Jr., Principles of Traveling Wave Tubes , Boston, MA: Artech House, 1994, Sec. 
 Delano, R. H.: A Theory of Target Glint or Angular Scintillation in Radar Tracking, Proc. I RE, vol. 
 I, pp. 174-187, 1959.  1 1 I. 
 819-828. November. 1976. 
 Milne, K.: The Combination of Pulse Compression with Frequency Scanning for Three Dimensional Radars, Radio Electron. Eng., vol. 28, pp. 
 Any use is subject to the Terms of Use as given at the website. Reflector Antennas. 12.38  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 FIGURE 12. 37 Ground-based S-band 9-meter dual reflector and dual-pol feed: a) photo of system; b)  mechanical CAD rendering showing panelized reflector surface and support structure; and c) dual-polarized  waveguide feedhorn ( Courtesy General Dynamics C4 Systems ) FIGURE 12. 
 BEAM CLUTTER -,# IN FIGURE  ARE USED FOR FORMING MAIN 
 24.9 over a month, the medians will approximate the curves of Fig. 24.9 closely. In addi- tion, the upper and lower decile values of the measured monthly families of F2 critical frequencies will deviate from the median by about ±25 percent. 
 The large cross section and the close range can result in considerable altitude ret Llrri  The clutter illuminated by the antenna sidelobes in directions other than directly benoatti  the aircraft may have any relative velocity from + v to - v, depending on the angle made by  the antenna beam and the aircraft vector velocity (v is the aircraft velocity). The clutter  spectrum contributed by these sidelobes will extend 2vlA Hz on either side of the transmitter  frequency. The shape of the spectrum will depend upon the nature of the clutter illuminated  and the shape of the antenna sidelobes. 
 BASED THEORETICAL  R  VARIATIONS FOR FIRST 
 BEAM CLUTTER OR GROUND MOVING TARGETS AND STILL NOT RESULT IN DOPPLER BLIND SPEEDS FOR TARGETS OF INTEREST  - 
 have deployed Type I and Type II space- based radars. This section describes some of these SBR systems. STS Rendezvous Radar.1'15'36 The Integrated Radar and Communications Subsystem (IRACS) was developed by Hughes Aircraft Company for use on the Space Transportation Systems (STS). 
 13.6  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 The element must be chosen to give the desired polarization, usually vertical or  horizontal. The special case of circular polarization is discussed below. If polarization diversity is required or if an array is required to transmit one polar - ization and receive the orthogonal or both polarizations, either crossed dipoles or  circular or square radiators seem suitable. 
 Skolnik, M. I.: An Empirical Formula for the Radar Cross Section of Ships at Grazing Incidence,  IEEE Trans., vol. AES-10, p. 
 The design ofthemounting oftheradome should have due considera- tion. Servicing requirements necessitate removal oftheradome. The means ofmounting theradome must bequick-fastening aswell asstrong. 
 1933.  14. Jay. 
 Gunn elements were used in the oscillators.  The device had only one  main beam direction.  Sample lines were constructed on various occasions, but it was recog- nizable that no cost -effective manufacturing was to be expected. 
 Furthermore, at the higher frequencies the antenna sidelobe levels can be lower, making it  more diflicull for sidclohe jamming. 1 lowever, the advantages of operating against jammers al  the higher frequencies arc balanced in part by the disadvantages of the higher frequencies,  especially a hove J, hand, for long-range air-surveillance radar.  The noise that enters the radar via the antenna sidelobes can be reduced by coherent  sidelohe cancelers. 
 Turley, “Adaptive  cancellation of nonstationary interference in HF antenna arrays,” IEE Proc ., vol. 145, pt. F,   no. 
 R. J. Lefevre, “Bistatic radar: New application for an old technique,” WESCON Conf. 
 POINT TRANSMITTERS  AND MANY OTHER SPECTRUM USERS HAVING REGULAR SCHEDULES  AS IS EVIDENT FROM &IGURE   WHICH PLOTS THE POWER SPECTRAL DENSITY AT K(Z RESOLUTION FOR HIGH AND LOW SOLAR ACTIVITY  SUMMER AND WINTER  DAY AND NIGHT &)'52%   (& ACTIVITY OVER THE n -(Z FOR LOW AND HIGH SUNSPOT NUMBERS L  H   SUMMER AND  WINTER S  W   AND DAY AND NIGHT D  N   AS MEASURED AT LATITUDE  3  LONGITUDE  % 4HE DATA IS  TAKEN FROM *ULIAN DAYS  AND  OF  AND  . 
 Of these dozen blocks, the public news media generally show only the antenna and displays. The rest of the blocks are ''unsung heroes," but they are equally important to the system and can be equally interesting from a design standpoint. FIG. 
 3.8and 39theobserved return powerl from aB-26 ]Ashby etal.,RLReports X’o.931, Apr. 8,1946, andNo.914, Mar. 28,1946,. 
 A common form of frequency-measuring device is the cycle counter, which mcasurcs thc  number of cycles or half cycles of the beat during the modulation period. Thc total cycle count  is a discrete number since the, counter is unable to measure fractions of a cycle. The  discreteness of the frequency measurement gives rise to an error called thefiurd error, or  st^'^)  error. 
 REFLECTOR EFFECTS HAVE BEEN USED TO DESCRIBE STRONG RETURNS  FROM BUILDINGS AT NON 
 ~lic flr~cttl;~tiv~l is assitrned to be independent from scan to scan as in case  1. I>(II lllc ~>rol>;~l>ility-dc~tsity f'r~rlctiort is givcn by  1)(4 = 4: ex,, (- on\  C'c~scl 4. 7'llc flilcttlatiori is prrlse to pulse according to Eq. 
 2202–2212, 2000. 54. T. 
 Another promising approach tothe condenser design problem isthe electrochemical formation ofvery thin insulating films onmetal (such asthose employed intheelectrolytic condenser) onwhich alayer ofmetal isthen deposited, High capacity per unit area results from the very small spacing, but the insulating film must beable towithstand the extremely high field strengths thus imposed. Further attention tothe details ofmechanical design ofcondenser fittings-containers, bushings, connectors, and thelike—is also required. using conventional dielectrics can still beconsiderably reduced. 
 V.: Prediction of Radar Range, chap. 2 of" Radar Handbook," M. I. 
 Gamble. W. L., and T D. 
 2.8b, Li(40) is 3.5 dB and Li(lO) is 1.7 dB, so that  the collapsing loss is 1.8 dB. 1 t is also possible to account for the collapsing loss by substituting  into the radar equation of Eq. (2.33) the parameter Ei(m + n) for Ei(n), since Ei(n) = 1/Li(tl). 
 ING AN OBLONG APERTURE  AS SHOWN IN &IGURE B 
 Iftherequired sca~anglecanbe limitedtoamuchsmallerangular regionthenumberofradiating elements andthenumberof phaseshifterscanbereduced. Thiscanresultinasimplerandcheaper phased-array radar thantheconventional arraythatmustscanawideangleintwoorthogonal coordinates. Although theconventional phased-array radarhasnotseenextensive application because of itshighcostandcomplexity, thelimited-scan arrayhashadsignificant application because itis morecompetitive inbothperformance andcosttomechanical scanning antennas. 
 LOG FREQUENCY PLOT 4HIS PROCEDURE BECOMES PARTICULARLY SIMPLE WHEN A -4) &)2 FILTER USING BINOMIAL COEFFICIENTS IS ASSUMED 4HE LOCATIONS ALONG THE FREQUENCY AXIS WHERE THE STRAIGHT LINES INTERSECT ARE CALLED  BREAK FREQUENCIES  4HIS SIMPLIFIED  PROCEDURE  WHICH IS SIMILAR TO THAT PRESENTED IN 6IGNERI ET AL   IS DESCRIBED IN THE  FOLLOWING PARAGRAPHS 4HE FIRST OF THE THREE ADJUSTMENTSOSCILLATOR NOISE SELF 
 This provides slow tuning over amuch wider frequency range (see Vol. 7ofthis series).. Ablock diagram ofatypical AFC system isshown inFig. 
 MOTION SPECTRUM  STAG 
 69. S. J. 
 364–464, 527–589, 590–593, 594–631.  4. L. 
 LINE CONFIGURATIONS RELY ON &%4 SWITCHES TO SWITCH LENGTHS OF TRANSMISSION LINE IN AND OUT OF THE CIRCUIT AND ARE TYPICALLY USED FOR HIGHER FREQUENCIES WHERE LESS CHIP AREA IS NEEDED ,OADED 
 over the grazing angles or usual interest. a radar  which must detect targets over land has a more dirficult task than one which must detect  targets over the sea. Even though a radar at sea might not be bothered by sea clutter. 
 13.50  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 preamplifier so that further processing may include lossy circuits. The receiving  channel may be split three ways, as indicated in Figure 13.33 b, into the sum and the  elevation and azimuth difference channels. These are then weighted and summed  with corresponding outputs from the other subarrays. 
 END /N THE OTHER HAND  THERE ARE MAJOR ADVANTAGES TO BE HAD  SUCH AS SIMULTANEOUS RECEPTION OF SEVERAL RADAR SIGNALS ON DIFFERENT FREQUENCIES  SO A SINGLE RECEIVER CAN SERVICE MORE THAN ONE RADAR TRANSMITTER #ALIBRATION 4HE CONVENTIONAL BEAMFORMING PROCESS IN AN IDEAL MULTI 
  +    !$ .OISE ,EVEL D"M(Z 
 Fair clutter rejection. Poor clutter rejection. Interference rejection No SNR loss. 
 TheE-2Cradome weighsjustover 2000lb.Theentireunitrotatesata 6rpmrate.Ithousesabroadside arrayofVagi-type endfireelements. Figure7.30E-2CAEWaircrartwithrotodome antenna.. Weather eflhcts. 
 J. Anderson, A. Y . 
 This has been done inadevice called the “Ground-position Indicator,” orGPI. The GPI provides anelectronic index forthe PPI tube ofthe radar intheform oftheintersection ofacircle ofconstant range and anazimuth. SEC. 
 When this condition applies, the S.4R is called unfocused. Figure 14.2 defines  the maximum aperture of an unfocused SAR srtch tlrat the difference between the minimum  and lnaxi~nl~rn (two-way) paths is a quarter wavelsngtl I From this geometry it can be derived  that the effective length Le of the synthesized anteri~la 1 m, so that the cross-range resolu-  t~on for I he unfocused synthetic antenna is  a,, = m/2 (14.5)  X  X ~-----------2=Zs Tarqet ,  Figure 14.2 Geometry of the unfocused SAR.  518INTRODUCTION TORADAR SYSTEMS x x :1 x­x~xlI/ip xFigure14.1Geometry ofthesynthetic aperture radar traveling withavelocity v.Theradartransmits apulseat eachposition marked byanx.fp=pulserepetition frequency. 
 Inmodulo-two addition, theoutputiszerowhentheinputsarealike[(0,0)or(I,1)] andisonewhentheinputsaredifferent.Itisequivalent toordinary base-two addition with onlytheleastsignificant bitcarriedforward. Amodulo-two adderisalsocalledanexclusive-or gate.AnII-stageshiftregisterhasatotalof2"different possible states.However, itcannothave thestateinwhichallthestagescontainzerossincetheshiftregisterwouldremaininthisstate andproduce allzerosthereafter. Thusann-stageshiftregistercangenerate abinarysequence oflengthnogreaterthan2"- 1beforerepeating. 
 STATE MICRO 
 AP-8, pp. 17-22, January, 1960.  87. 
 Amitay, N., V. Galindo, and C. P. 
 When the aircraft receded  froin the receiver, it was possible to detect the beats to about an 8-mile range.  By June, 1935, the British had demonstrated the pulse technique to measure range of an  aircraft target. This was almost a year sooner than the successful NRL experiments with pulse  radar. 
 Any decrease in time to scan the volume or any increase in the volume searched must be ac- companied by a corresponding increase in the product Pav Ae. Note that the fre- quency does not enter explicitly. Jamming. 
 94. pt. 111, 1717. 
 38, pp. 1422- 1428, December, 1950.  19. 
 There is no reference from the transmission oscillator to the  receiver, therefore non -coherent pulse Radar cannot measure Doppler and thus only the di s- tance and not the speed of a target can be determined.     Figure 8.4  Simple, non -coherent Radar.  . 
 3HALOM  h4HE INTERACTING MULTIPLE MODEL ALGORITHM FOR SYSTEMS WITH  -ARKOVIAN SWITCHING COEFFICIENTS v )%%% 4RANS  VOL !#n  NO   PP n  !UGUST   ! -OREIRA  h)MPROVED MULTILOOK TECHNIQUES APPLIED TO 3!2 AND 3#!.3!2 IMAGERY v  )%%%  4RANS ON 'EOSCIENCE AND 2EMOTE 3ENSING  VOL   NO   PP n  *ULY   7 'OJ  3YNTHETIC !PERTURE 2ADAR AND %LECTRONIC 7ARFARE   $EDHAM  -! !RTECH (OUSE  )NC    # * #ONDLEY  h4HE POTENTIAL VULNERABILITY TO INCREASED BACKGROUND NOISE OF SYNTHETIC APER 
 Typically, the pattern shaping is enabled by a doubly curved reflector  fed from a point-source primary feed. An example from Easat Antennas is illustrated  in Figure 22.7. This is a 7.5 meter reflector antenna with a 35 db gain at 9.3 GHz. 
 Although a  well-designed and engineered receiver will not limit the received signal under normal circum­ stances. intensity modulated CRT displays such as the PPI or the B-scope have limited dyna­ mic range and may limit. Some receivers, however, might employ limiting for some special  purpose, as for pulse compression processing for example. 
 45 4 7 Instead of using ordinary dielectric materials for lens antennas, it is  possible to construct them of artificial dielectrics. The ordinary dielectric consists of molecular  particles of microscopic size, but the artificial dielectric consists of discrete metallic or dielec­ tric particles or macroscopic size. The particles may be spheres, disks, strips, or rods imbedded  in a material of low dielectric constant such as polystyrene foam. 
 8.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 processed coherently. The order in which the frequencies are generated greatly influ - ences the nature of the ambiguity function of the burst. If the frequencies are monotoni - cally increasing or decreasing, the waveform is simply a stepped approximation to an  LFM, which has a ridge in its ambiguity function (Figure 8.25). 
 (13.8). First, the clutter echo power must be large  compared to the receiver noise power for Eq. ( 13.8) to be valid. 
 PULSE 4HE POINT BEING MADE HERE IS THAT -4) SYSTEM OPERATION DOES NOT DEPEND ON THE FREQUENCY RESOLUTION OF TARGETS FROM CLUTTER 4O PROVIDE FREQUENCY RESOLUTION WOULD REQUIRE MUCH LONGER DWELL TIMES ON TARGET THAN TWO PULSES SEPARATED BY A SINGLE 02) 3UCH EXTENDED DWELL TIMES IS ONE OF THE FUNDA 
 Remote Sensing , vol. 8, no. 11, pp. 
 ZONTAL RANGE IS VERTICAL 4HE PAIRED ECHOES IN CROSSRANGE ARE CHARACTERISTIC OF A  VIBRATING TARGET TRUCK WITH ENGINE RUNNING  IN A 3!2 IMAGE 4HE FREQUENCIES  (Z AND  (Z  ARE PECULIAR TO THE SPECIFIC TRUCK THAT WAS IMAGED  #OURTESY  OF .ORTHROP 
 Nutation, which preserves the plane ofpolarization, is even  rnorc difficult. Rotation of tlie hearris causes the plane of polarization to rotate which can  carlqc undcsirahle target :iniplttirdc fliictuatiotis at tlie scan rate. Altliougli such fluctuations  are theoretically removed by the rtionopulse type of processing, in practice the removal is not  corlij~lctc arid ntlgi~lat cr rot can rcsi~lt.~"itli nloderii solid-state tecllnology, the need for a  tliird receiver in tile conventio~ial tiiotiopi~lse tra,cker might not be as difficult to realize in  IJI;~CIICC ;iq 11ic cor~~l~lcxity of 11tol~c1 ly scii~iriirig a pair of sqt~ititcd hcanls. 
  %UROPE  
 Even with STAP, sidelobe clutter is a major limitation.67,68,93 Both sidelobe  and main-beam clutter can be minimized by narrow doppler and/or range bins (i.e.,  resolution cells), which imply longer dwell times and higher transmit bandwidth. One example method for selecting a set of PRFs for MPRF is given in Eq. 5.1. 
 This chapter is devoted to the description of the ECCM techniques and design prin - ciples to be used in radar systems when they are subject to an ECM threat. Section 24.2  starts with a recall of the definitions pertaining to EW and ECCM. The topic of radar  signals interception by EW devices is introduced in Section 24.3; the first strategy to  be adopted by radar designers is to try to avoid interception by the opponent electronic  devices. 
 To obtain n~oZiliZn oile pulse  per beam position and/or increase the unambigilous range rcqi~ires some comprornises or an  increase in complexity. The compromises require a fiittcr beamwidtit or a slower scau rate.  Some benefit can be obtained by using a pulse repetition frequency (prf) that varies with  elevation angle. 
 Also, a good MTI is easier to  ;icliicve aricl the efl'ects olweatlier are less at these frequencies. The preferred frequencv range  for an aircraft-tracking radar is the upper portion of the niicrowave band (C' or X bands) sitice  it is easier to obtain the wide bandwidths and narrow beamwidths for precision target tracking  than at the lower frequencies. TIlils tracking radars differ significantly from surveiilaticc  ratiars. 
 X band, horizontal po\ariLation. (from Kut: u11d  Spetner,38 Courtesy J. Res. 
 30. Kumlner, W. H.: Feeding and Phase Scanning, "Microwave Scanning Antennas, vol. 
 F.: Frequency Scanning Aerials, Electronic Engineering, vol. 36, pp. 222-226, April,  1964. 
 POWER AMPLIFIER (0!  IS THE FIRST OF ITS KIND FOR A SPACE 
 C. Dobson and F. T. 
 July,1959. 65.Wei!,H.,M.L.Barasch, andT.A.Kaplan: Scattering ofElectromagnetic WaveshySpheres. Ullit· .\1ichigall Radiatioll Lal>.Studies illRadarCrossSectiolls X.Rept.2255-20- TonConIract:\F 30(6ll2)-107ll, July,1956. 
 The three-pulse canceler is  even better. (As mentioned previously, maximizing the average improvement factor might not  be the only criterion used in judging the effectiveness of MTI doppler processors.)  If a two-or three-pulse canceler is cascaded with a doppler-filter bank, better clutter  rejection is provided. Figure 4.26 shows the improvement factor for a three-pulse canceler and  an eight-pulse filter bank in cascade, as a function of the clutter spectral width. 
 3.7  Spurious Distortion of Radiated Spectrum  ..........  3.7 . This page has been reformatted by Knovel to provide easier navigation. 
 Krauss, H. L., C. W. 
 Radford, M. F .. and R. 
 10.2 to be equal to the cross correla-  tion between the received signal and the transmitted signal [Eq. (10.18)]. When the received  echo signal from the target is large compared to noise, this may be written as  Output of the matched filter = sr(t)s*(t - TX) dt (1 1.46)  where sr(t) is the received signal, s(t) is the transmitted signal, s*(t) is its complex conjugate,  and Tk is the estimate of the time delay (considered a variable). 
 16.9&. The result is as though the aircraft were flying at a speed and heading such that the displacement A1 - A 2 occurs during an interpulse period. The TACCAR circuits could center the resultant spectrum at zero-doppler frequency. 
  AND TRANSMITTER 
 AP-8, pp. 17-22, January, 1960.  87. 
 FACTOR %##-  4HIS IS A GENERIC %##- TECHNIQUE THAT COVERS THE ABILITY OF  AN AIR DEFENSE OFFICER  A RADAR OPERATOR  A COMMANDING OFFICER  ANDOR ANY OTHER AIR DEFENSE ASSOCIATED PERSONNEL TO RECOGNIZE THE VARIOUS KINDS OF %#-  TO ANALYZE THE EFFECT OF THE %#-  TO DECIDE WHAT THE APPROPRIATE %##- SHOULD BE  ANDOR TO TAKE THE NECESSARY %##- ACTION WITHIN THE FRAMEWORK OF THE PERSONS COMMAND STRUCTURE (OWEVER  THE HUMAN OPERATOR IS LESS EFFECTIVE AGAINST A SIMULTANEOUS ATTACK OF MANY ENEMY VEHICLES SUPPORTED BY A STRONG %#- FORCE !N OPERATOR CONFRONTED WITH A LARGE MIX OF %#- TYPES AND A LAR GE NUMBER OF %##-  TECHNIQUES IS LIKELY TO DO THE WRONG  THING ANDOR REACT TOO SLOWLY )N THIS SITUATION  IT MIGHT BE PROPER TO RESORT TO AUTO 
 OF 
 Pylons as tall  as 95 ft have been built, and it is customary to treat them with radar-absorbing material  to suppress the echoes from the leading and trailing edges. The obvious advantage of the metal pylon is its superior weight-carrying capabil - ity compared with that of strings and plastic foam columns. However, because the  top of the pylon is small, the rotation mechanism needed to vary the aspect angle of  the target must be embedded in the target itself. 
 DUCE THE DESIRED SIDELOBE LEVELS "ECAUSE THIS AMPLITUDE WEIGHTING PRODUCES A TAPER LOSS ON RECEIVE  USING FULL AMPLITUDE AND PHASE CONTROL FOR NULLING THE RADIATION PATTERN IS LESS OF A CONCERN THAN ON TRANSMIT 4HE INCORPORATION OF ADAPTIVE NULLING INTO PHASED ARRAY ANTENNAS ALLOWS PHASED  ARRAYS TO HAVE ADAPTIVE ANTENNA PATTERNS ON RECEIVE !DAPTIVE TECHNIQUES ARE USED TO SENSE AND AUTOMATICALLY RESPOND TO A TIME 
 Thus,thegainssodefineddescribe themaximum concentration ofradi­ atedenergy.Itisalsocommon tospeakofthegainasafunction ofangle.Quiteoftenthe ordinate ofaradiation patternisgivenasthegainnormaliz~d tounityandcalledrelativegain. Unfortunately thetermgainisusedtodenoteboththepeakgainandthegainasafunction of angle.Confusion astowhichmeaning iscorrectcanusuallyberesolved fromthecontext. Thedefinitions ofpowergainanddirective gainweredescribed aboveintermsofa transmitting antenna. 
 29-30. May 1, 1958, AFCRC-TR-58-145(I), ASTIA Document 152409.  61. 
 INDICES Itisalways desirable and usually mandatory toprovide some form ofquantitative indices ormarkers forthe radar indicator. These may consist simply ofagridwork oflines or,when high accuracy isrequired, ofone ormore movable indices. Inaddition, itisoften desirable to superpose some form ofmap orchart onaradar display, inorder topro- vide accurate correlation with fixed echoes fornavigational purposes or toshow ataglance thegeographical position ofaship oraircraft target. 
 17.1  Nomenclature  ....................................................  17.1 Applications  .......................................................  17.1  PRFs  ................................................................. 
 14. R. Bernard and D. 
 (Whenreferredtotheradiation fromanisotropic antenna, thepeaksidelobes froma low-sidelobe antenna mightbeapproximately 10to15dBbelowtheisotropic level.)The. achievement of extremely low sidelobes requires the antenna to be well constructed so as to  maintain the necessary mechanical and electrical tolerances. It takes only a small deviation of  the antenna surface to have an increase of the peak sidelobe of a very low sidelobe antenna. 
 3519A; Switch unit, type 207B; Waveform generator, type 34; Receiver, type R3585; Indicator unit, type 163C; Scanning unit, type 12 and type 53; Attenuator, type 53 (or attenuator, type 58). Attenuator control unit, type 448 (or type 492 for attenuator, type 58); Tuning control unit, type 444; Wavemeter type 1632 (echo box); Lucero, TR 3566; Control unit, type 411 (for switch unit, type 247); Two amplifying units, type 171 (for control unit, type 411); Switch unit, type 247 (waveguide switch); Power unit, type 617A; Power unit, type 567; Monitoring unit, type 158A. It should be noted that ASV Mk. 
   .   2!$!2 2%#%)6%23   È°£ MUST BE CONCERNED WITH INTERNAL SIGNAL SOURCES -4) AND PULSE DOPPLER RADARS ARE  PARTICULARLY SUSCEPTIBLE TO ANY SUCH INTERNAL OSCILLATORS THAT ARE NOT COHERENT  IE  THAT DO NOT HAVE THE SAME PHASE FOR EACH PULSE TRANSMISSION 4HE EFFECT OF THE SPURIOUS SIGNAL IS THEN DIFFERENT FOR EACH RETURN  AND THE ABILITY TO REJECT CLUTTER IS DEGRADED  &)'52%  0HASE NOISE ALIASING IN A PULSE DOPPLER SYSTEM                   
 ALONE RADAR CONSOLES ARE NO LONGER NECESSARY  ALLOWING IMPROVEMENTS TO THE ERGONOMIC LAYOUT OF A SHIPS BRIDGE 5SER INPUT DEVICES VARY BY MANUFACTURER 3OME SOLUTIONS RELY ON LITTLE MORE THAN  A TRACKER BALL AND THREE CONTROL BUTTONS /THERS HAVE A NUMBER OF DEDICATED SWITCHES AND ROTARY CONTROLS  AS WELL AS A CURSOR CONTROL SUCH AS A TRACKER BALL OR JOYSTICK . 
 INVARIANT  IT BECOMES USEFUL WHEN COMPARING  BISTATIC TO MONOSTATIC RANGE PERFORMANCE &INALLY  AN OVAL OF #ASSINI IS ESTABLISHED AS A FUNCTION OF THE BASELINE RANGE   ,  NORMALIZED TO THE BENCHMARK RANGE   2 - "ASED  ON THIS OVAL  MAXIMUM AND MINIMUM DETECTION RANGES AND THE COVERAGE AREA ARE CALCULATED  ALL AS A FUNCTION OF  2 - 4HIS PROCEDURE IS ALSO USED TO DEFINE BISTATIC  OPERATING REGIONS 2ANGE %QUATION  4HE RADAR RANGE EQUATION FOR #7 OR COHERENT PULSE RADARS  IS MODIFIED FOR BISTATIC OPERATION AND THEN SOLVED FOR THE BISTATIC MAXIMUM RANGE PRODUCT  2 4 22 MAX      MAX220T'' & & K4& % .42O42 "4 2 ON AVL  R POO4 2,, § ©¨¶ ¸·    WHERE  24   4RANSMITTER 
 TIPLE 
 35, pp. 489 ·492.  8 t. 
 2.12).  The loss of the range information and the collapsing loss may be eliminated by first  quantizing the range (time) into small intervals. This process is called range gating. 
 Waveguide.—Although ametallic pipe ofalmost any shape will transmit orguide electromagnetic waves iftheir wavelength inairis short enough, rectangular tubing whose internal dimensions have aratio between 2.0and 2.5hasbeen almost universally adopted where theprob- lem issimply thetransfer ofmicrowave energy. (Use ofround guide in the special case where axial symmetry isrequired isdiscussed inalater paragraph.) Adetailed understanding ofthe propagation ofwaves ina region bounded byconducting walls can only beobtained from thesolu- tion ofMaxwell’s equations. Practically, however, the results ofthe mathematical analysisl have come tobeused inaprocedure which retains most oftheconcepts oftransmission-line theory, with equivalent lumped reactance connected atsuitable points toaccount forthe effects of discontinuities. 
 Brown. B. P.: Radar Height Finding. 
 Conservative design suggests that the measurement should  be concentrated near the reflection from that surface. Hence, ocean-viewing altim - eters have a small range window whose position tracks the delay and strength of the  §  The Geosat ERM orbit was chosen for political as much as for technical reasons. It followed the Seasat orbit  (1978) that had established a well-known precedent.70 ch18.indd   38 12/19/07   5:14:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
  
 SIDE  THE CENTER 
 FREE DETECTION PROCEDURE FOR MULTIPLE 
 R.: "Vacuum Tubes," McGraw-Hill Book Company, New York, 1948.  22. Ying<;!, T F .. 
 FLYING TARGET REACH AT LEAST  SAY  AN   0 D BEFORE ANY GAIN  LIMITING IE  THE USE OF !'#  OCCURS  THE DYNAMIC 
 CELL BY #0) BASIS 4HESE &)2 CLUTTER FILTERS HAVE THE NARROWEST REJECTION NOTCHES THAT CAN BE OBTAINED  WITH FIVE PULSES AND THE INDICATED LEVEL OF FIXED CLUTTER REJECTION (OWEVER  THE NOTCHES ARE SIGNIFICANTLY WIDER THAN THOSE OF THE ELLIPTIC FILTERS THUS  THEY WILL HAVE GREATER BIAS FOR MEASUREMENT OF WEATHER INTENSITY WHEN THE WEATHER RADIAL VELOCITY IS ZERO &OR PHASED ARRAY RADARS  &)2 FILTERS SIMILAR TO THOSE DESCRIBED FOR THE !32 
 F.: A Review of Ferrites for Microwave Application, Proc. I £EE, vol. 63, pp. 
 The s~called ‘{magic T”pro- vides amethod ofdecoupling thesignal and local-oscillator inputs that does not depend onanexcess oflocal-oscillator power. See Micrmuaue Mizsrs, Vol. 16, Chap, 6.. 
 6.7, the pulling  figure is approxiuiatcly 4 M 111. Tllc l>i~llirlg figures of coaxial magnetrons are lower by a factor  of 3 to 5 than tliose of convcritio~ial nlagrietroiis.  Tuning. 
 AP-13, pp. 141–149,  January 1965. 74. 
 Whetton, C. P.: Industrial and ~cie"tific ~~~lications of Doppler Radar, Micro\rsarr J.. vol. 
 Thus an n-stage shift register can generate a binary sequence  of length no greater than 2" - 1 before repeating. The actual sequence obtained depends on  both the feedback connections and the initial loading of the register. When the output se-  qucrlce of at1 t~-stage shift register is of period 2" - 1, it is called a maxintal lertgtll seqtcence, or  ??I-seqiter~ce. 
 7.5. Buildings in the vicinity of  ground-based radar, and masts and other obstructions in the vicinity of shipboard antennas  can also degrade the radiation pattern because of aperture blocking. 131  -20 C  0  -20 E !ij-e  Q)  ,,... 
 16.29 MTI improvement factor for a double-notch canceler tracking two spectra as a function of the normalized spectra sep- aration A//fr. Normalized spectral width <jc/fr = 0.01. frequency bands (X or K) are chosen to maximize the doppler shift. 
 Lett. 2016 , 7, 219–228. [ CrossRef ] 22. 
 SQUARES CHANNEL ESTIMATO R  4HESE NOISE FIGURES  ARE SIGNIFICANTLY HIGHER THAN THOSE OBTAINED IN THE 53 RADAR 
 PULSE OR DWELL 
 ING  WAVEGUIDE 
   PP n  3EPTEMBER    h&INAL REPORT ON INSTRUMENTATION RADAR !.&03 
 NAL PROCESSING v IN  .!%#/.  2ECORD   PP n AND REPRINTED IN $ + "ARTON   #7 AND  $OPPLER 2ADARS  3ECTION )6 
 F.: Performance Data for a Double-Threshold Detection Radar, IEEE Trans., vol. AES-7,  pp. 142-146, January, 1971. 
 2010. Available online: https://www.centauri-dreams.org /?p= 15475 (accessed on 30 November 2017). 4. 
 CLUTTER RATIO BY DESIGNING A MODIFIED OPTIMIZED FILTER IS USUALLY INSIGNIFICANT 7HEN THE DURATION OF THE TRANSMITTED RADAR SIGNAL  WHETHER #7 OR A REPETITIVE TRAIN  OF . IDENTICAL PULSES  IS COMPARABLE WITH OR GREATER THAN THE RECIPROCAL OF ANTICIPATED  TARGET DOPPLER SHIFTS  THE DIFFERENCE BETWEEN A CONVENTIONAL WHITE 
 Ground-based SAR interferometry for monitoring mass movements. Landslides 2004 ,1, 21–28. [ CrossRef ] 8. 
 A suitable device for switching low-level signals is a PIN diode modulator, but with it there is difficulty in obtaining an exact reproduction of the pulse shape produced by a high-power amplifier. On the other hand, the rather large phase perturbation produced by the PIN diode modulator on the leading edge of the pulse is repeated pulse to pulse and produces spectral energy only at multiples of the repetition frequency, where measurements are impossible in any case. Typical additive-noise measurements made on a variety of FM and CW sources at the Harry Diamond Laboratories17 and elsewhere are shown in Fig. 
 53-58, London, 1977. 18. Ewing, E. 
 Electrical Properties ofCathode-ray Tubes.—Cathode-ray tubes areclassified as“electrostatic” or“magnetic” inaccordance with themethod ofdeflection. Anexample ofeach isgiven inFig. 13.1. 
 Lax, B .. K. J. 
 ING DWELL THAT CONSISTS OF THREE #0)S 4HE #0)S MUST USE DIFFERENT 02&S AND MAY ALSO EMPLOY DIFFERENT 2& FREQUENCIES 4HE DIFFERENT 2& FREQUENCIES CHANGE TARGET 2#3 STATISTICS FROM 3WERLING  TO 3WERLING   AND THUS LESS RADAR ENERGY IS REQUIRED FOR HIGH PROBABILITY OF DETECTION  4HE #0)S MUST HAVE   SUFFICIENT TRANSMITTED PULSES SO THAT N RETURNS ENOUGH TO FILL AN  N 
 Tuley, Radar Cross Section , 2nd Ed., Boston: Artech  House, 1993. 110. M. 
 The radar receiver measures the time  between the leading edges of the last transmitting pulse and the echo pulse. It is possible that an  echo will be received from a long range target after the transmission of a second transmitting pulse.                 In this case, the radar will determine the wrong time interval and therefore the wrong range. 
 81-84, January, 1974.  136. Skolnik, M. 
 MITTED PULSE 4HIS IMPLEMENTATION REPRESENTS THE MOST BASIC TWO 
 Peeples, W. R. Sill, T. 
 Although it is difficult to generalize, the MTI radar seems to be the more  widely used of the two, but pulse doppler is usually more capable of reducing clutter.  When the prf must be so high that the number of range ambiguities is too large to be  easily resolved, the performance of the pulse-doppler radar approaches that of the CW doppler  radar. The pulse-doppler radar, like the CW radar, may be limited in its ability to measure  range under these conditions. 
 NUMBER OF PULSES FIG. 2.4 Required signal-to-noise ratio (detectability factor) as a function of number of pulses noncoherently integrated, linear detector, nonfluctuating target, and 0.5 probability of detection. (From Ref. 
 When the satel- lite is operating in midaltitude orbits, exposure to the earth's Van Allen belts will be predictable and its effect on radar electronics will be functions of the inherent hardness level of the components and the shielding used. (Reference 34 provides the trapped radiation data for proton and electron flux that has been measured as a function of altitude.) Figure 22.132 shows the total 5-year dose in rads (Si) that satellites in orbits between 350- and 6500-nmi altitudes will experience as a func- tion of the aluminum shielding used. It appears that current technology in integrated-circuit hardening should produce a total dose hardness of about 5(1O)5 rads (Si) for devices that are suitable for the SBR T/R modules. 
 OUTPUT LEVELS n WMM  &)'52%   4YPICAL TWO 
      SSQQ SSJJ QQPR      SS SSJJ 
 Figure 4.1226 shows the amplitude response for (1) a classical three-pulse canceler with  sin2 nfd T response, (2) a five-pulse "optimum " canceler designed to maximize the improve-  ment factor3 and (3) a 15-pulse canceler with a Chebyshev filter characteristic. (The amplitude  N  is normalized by dividing the output of each tap by the square root of w:, where  I- I  MTIANDPULSE'DOPPLER RADARtil Thetransversal filterwithalternating binomial weights iscloselyrelatedtothefilter whichmaximizes theaverageoftheratioIe=(SjC)outj(SjC)in, where(SjC)OU!isthesignal-to­ clutterratioattheoutputofthefilter,and(SIC);nisthesignal-to-clutter ratioattheinput.3•4 Theaverageistakenovertherangeofdopplerfrequencies. Thiscriterion wasfirstformulated inalimited-distribution reportbyEmerson.5TheratioIewascalledintheearlyliterature the referellce gaill,butitisnowcalledtheimprovement factorforclutter.Itisindependent ofthe targetvelocity anddepends onlyontheweights Wi,theautocorrelation function (orpower spectrum) describing theclutter,andthenumberofpulses.Forthetwo-pulse canceler (asingle delayline).theoptimum weightsbasedontheabovecriterion arethesameasthebinomial weights. 
 BASED RADAR 3"2  DUR 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar.  GROUND PENETRATING RADAR  21.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 Unprocessed GPR images often show “bright spots” caused by multiple inter - nal reflections as well as a distortion of the aspect ratio of the image of the target  caused by variations in the velocity of propagation. 
 -/6/96 
 PLER PROCESSOR BECAUSE EACH FILTER MAY HAVE DIFFERENT VALUES OF CLUTTER ATTENUATION  AND COHERENT GAIN 3INCE EACH DOPPLER FILTER HAS A COHERENT GAIN THAT IS A FUNCTION OF TARGET DOPPLER  AN  AVERAGE VALUE OF SIGNAL 
 Radar forms an important part of a  vessel’s total navigation equipment fit. Increasingly, the bridge of a ship is designed  as an integrated concept, covering navigation, communications, engine control, and  cargo monitoring facilities. Figure 22.1 illustrates a modern integrated bridge system   (IBS) as fitted on a cruise ship. 
 The second type ofunbalance arises from thefrequency dependence ofattenuation -inthe delay-line medium. The square-law factor generally predominates. Compensation canbeobtained byinsert- inginthedelayed channel anLC-circuit tuned toafrequency much higher than the carrier frequency. 
 D. T. Sandwell and W. 
 Coverage is increased with aperture weighting at the expense of monopulse sen- sitivity and fundamental accuracy. The effect on the boresight monopulse sensi- tivity of Taylor aperture weighting for the sum beam and Bayliss aperture weight- ing for the delta beam is illustrated in Fig. 20.6£. 
 (7.31) represents the no-error radiation pattern reduced by the  factor, exp -P". The second term describes the disturbing pattern and represents a source of  sidelobe energy which depends on the mean-square phase error and the square or the correla­ tion interval. For small phase errors, when only the first term of the series (n = 1) need be  considered. 
 57, pp.  1260-1266, July. 1969. 
 RANDOM 
 These limiter settings cause the  residue due to transmitter noise and the residue due to other instabilities, such as quan - tization noise and internal-clutter motion, each to be equal to front-end thermal noise  at the canceler output. This allows maximum sensitivity without an excessive false- alarm rate. Limiter 1 is a very efficient constant-false-alarm-rate device against system  instabilities because it suppresses the instability noise in direct proportion to the clutter  signal strength but does not suppress at any time when the clutter signal is not strong. 
 TRANSMITTER SYSTEM CONSISTS OF  CROSSED 9AGI RADIATING ELEMENTS  EACH WITH ITS OWN SOLID 
 TIME 34!0 CAN PROVIDE  AND HOW FAST 
  #ONFERENCE    PP n  2 0 0ERRY  2 # $I0IETRO  AND 2 , &ANTE  h3!2 IMAGING OF MOVING TARGETS v  )%%% 4RANSACTIONS  ON !EROSPACE AND %LECTRONIC 3YSTEMS  VOL   NO   PP n  *ANUARY   * 2ODRIGUEZ AND * - -ARTIN  h4HEORY AND DESIGN OF INTERFEROMETRIC SYNTHETIC APERTURE RADAR v  )%% 0ROCEEDINGS  0ART &  VOL   PP n  !PRIL   2 "AMLER AND 0 (ARTL  h3YNTHETIC APERTURE RADAR INTERFEROMETRY v  )NVERSE 0ROBLEMS  VOL     PP 2 TO 2  !UGUST   3EE ALSO  & 'INI AND & ,OMBARDINI  h-ULTIBASELINE CROSS 
 6.12. Height-6nding with aFree-space Beam.’ Searchlighting. —The simplest form offree-space-beam height finder isone which measures elevation angle ofthe desired target directly, bypointing anantenna producing anarrow beam directly atthetarget and measuring theeleva- tion angle atthe antenna mount. 
 The  unused response, known as the image , is suppressed by the image-reject or single- sideband mixer shown in Figure 6.3. The RF hybrid produces a 90 ° phase differential  between the LO inputs to the two mixers. The effect of this phase differential on the  IF outputs of the mixers is a +90° shift in one sideband and a −90° shift in the other. 
 Wireless E11w .• vol. .'\3, pp. 83 96. 
 SURFACE MODELS  MAY LEAVE THE IMPRESSION THAT THEY HAVE  EMERGED AS A RIGOROUS PRODUCT OF AN INTEGRAL FORMULATION OF THE '"60  IT IS CLEAR THAT  THEY ARE NOT REALLY SCATTERING  THEORIES  BUT INSTEAD SCATTERING  PICTURES ASSEMBLED FROM  A GROUP OF MORE OR LESS PLAUSIBLE ASSUMPTIONS "UT WITH THE FAILURE OF THE MORE FORMAL '"60 THEORIES TO PROVIDE A GENERAL FRAMEWORK FOR PREDICTING AND UNDERSTANDING SEA CLUTTER  THESE MODELS HAVE BECOME THE BASIS FOR MOST ANALYTICAL APPROACHES TO MICRO 
 3.11 Error in the approximation of a logarithmic curve by linear approximation.MAXIMUM ERROR (dB) PERFORMANCEOF PRACTICAL LOGARITHMICDETECTORS Vj V1-I-SdB INPUT VOLTS (dB) 3.12 Method of measuring logarithmic- amplifier bandwidth. OUTPUT VOLTAGE RESPONSE ATCENTERFREQUENCY FREQUENCYDEVIATION . Analog Logarithmic Devices Logarithmic Detector. 
 In this chapter the meaning will ordinarily be evident from the context. Where confusion might otherwise re- sult, the term detection-decision device may be used to denote an automatic detector. Range units Statute miles Kilometers Thousands of yards Thousands of feetConstant, Eq. 
 The  transmitting array aperture, assuming ≈ 20 receive beams to be fitted into the transmit  beam, need be only ~ 120 m at this frequency. It follows from the radar equation and the considerations just discussed that trans - mit power in the range of 200–1000 kW is generally appropriate for detecting small  aircraft targets over a wide range of conditions. In order to radiate power efficiently,  the transmitting antenna elements tend to be large, resonant structures; for example,  the vertical log-periodic antennas used in the JORN system are up to 43 m tall. 
 CENTERED#ARTESIAN %ARTH 
 In oneexperimental designofaconical-shape radome, periodic resonant slotswerecutintothe metallic surfacesothatapproximately 90percentoftheradome surfacewasmetal.Withinib designband(8.8-9.0GHz)thetransmission properties werenearlyidealandaccommodakd scanning antennas transmitting arbitrary polarized signals.Thereduced respotlse outsidethe designbandreduces theeffectsofout-of-band interference andcanreducethenose-on radar crosssectionoftheaircraftatfrequencies otherthanthatforwhichtheantenna isdesigned Inconventional application, theradome isfixedandtheantenna isscanned. Itissametimes ofadvantage toconstruct theantenna andradome torotatetogether asaunit.Thisis calledarotodome. Theyhavebeenusedinground-based systems aswellasinairhorne aircraft-surveillance radarssuchasthe24-ft-diameter radome intheU.S.Navy'sE-2C (Fig.7.30)orthe30-ft-diameter radome ofAWACS. 
 Platform Polarization Band Boresight Incidence Angle Platform Height Platform V elocity ERS-2 VV C 23◦780 km 7500 m/s Figure 9. Enlargement of the shear-wave-generated eddy in Frame B. The ﬂight and look direction of ERS-2 SAR are indicated by black arrows. 
 LAW RELATION BETWEEN  THE VARIABLES  R    ^ 5N  WHERE N IS DETERMINED BY THE SLOPE OF THE LINE !N EXAMPLE IS  SHOWN IN &IGURE  /N THE OTHER HAND  WHILE THE TOTALITY OF THE .2, &2 RESULTS  APPEARED TO SHOW SATURATION FOR WIND SPEEDS ABOVE ABOUT  KT  THE HIGH AND LOW 
  
 Skolnik (ed.), New York: McGraw Hill, 1990, pp. 14.37–14.39,  16.8–16.28, 17.33–17.35, 23.5–23.13. 16. 
 When the feed must be pressurized  in order to sustain high power it is often easier to do so with a paraboloid fed by a single  point-source than with the larger line feed of a parabolic cylinder.  Still another variation of the parabola is the parabolic torus shown in Fig. 7 .16 and  discussed in Sec. 
 56. W. H. 
 G. R. Valenzuela, “Depolarization of EM waves by slightly rough surfaces,” IEEE Trans .,   vol. 
 The presence of N cavities in the magnetron results  in N /2 possible modes of operation. Each of these N /2 modes corresponds to a different RF  field configuration made up of a standing wave of charge. All the modes except the 1t mode are  degenerate: that is. 
 OND SHORT  PULSE  §S IN DURATION  AND AT A DIFFERENT FREQUENCY FROM THE LONG PULSE  WAS TRANSMITTED ALMOST IMMEDIATELY AFTER THE LONG PULSE )T DETECTS TARGETS WITHIN THE RANGE FROM  NMI OR LESS TO A RANGE OF ABOUT  NMI 4HE LONG PULSE EMPLOYS NONLINEAR &- PULSE COMPRESSION WITH A  PULSE COMPRESSION RATIO TO ACHIEVE A RANGE RESOLUTION OF LESS THAN  NMI AS REQUIRED FOR AN AIR 
 The re- quired difference-pattern slope is deter- mined by the derivative of the scan pat- tern, which differs from the DPCA criterion. This technique is known as step-scan compensation because the sys- tem electronically points the antenna slightly ahead of and behind boresight each pulse so that a leading and lagging pair are taken from successive returns to obtain the effect of the antenna remain- ing stationary. Figure 16.15 shows the improvement obtained by Dickey and Santa7 for single-delay cancellation. 
 Barley, and G. J. Rasr, Jr.: The Measurement of Noise in Microwave Transmitters,  IEEE Trans., vol. 
 MENTATION OF THE -4$ CONCEPT 4HE PREDICTED SUBCLUTTER VISIBILITY IMPROVEMENT FOR THE !32 
 PARAMETER METEOROLOGICAL RADARS ARE PRESENTED IN "RINGI AND (ENDRY   "RINGI AND #HANDRA  AND  IN THE COLLECTION OF PAPERS EDITED BY (ALL 7HEREAS LONGER 
 342 THEMAGNETRON ANDTHEPULSER [SEC. 105 and the high efficiency ofmagnetrons even atvery short wavelengths. Thepulse powers available extend over arange of105(0.02 kwto2000 kw) Frequency inMe/see FIG. 
 + ahc/ ac Trigger1 L. (a)r-----liTrigger L. (b) FIG.13.15.—Double external triggering of Eccles-Jordan circuits. 
 # RADARS THEY REPLACED   THE 732 
 A feed array in that region driven with suitable phase and amplitude can therefore efficiently form beams at any of the angles. This ability has been used in various systems as a means of forming agile beams over a limited sector. It has also been used as a means of shaping beams and of forming very low sidelobe illumination functions. 
 (It is of interest to note that the Japanese invented the magnetron before the  UK did, and Soviet Union engineers published a paper describing their magnetron  in the March 1944 issue of Proceedings of the Institute of Radio Engineers,  now the  Proceedings of the IEEE ; but the wartime chaos in the military developments of both  the Soviet Union and Japan was such that these inventions were not fully exploited  by these two countries during WWII.) The invention of the magnetron was important  because it allowed radar to be developed for use at microwave frequencies rather than  be limited to VHF and UHF frequencies. It caught the German electronic counter - measures effort off guard because they had no idea that the United Kingdom and the  United States could produce microwave radar. The success of the magnetron was a  large factor in the effective application of military radar by the United States and the  United Kingdom during World War II. 
 The reader may correctly surmise, from what has been said, that theeffective tem- perature ofthis element ofthecircuit isthat ofany surroundings ofthe antenna with which theantenna can exchange energy byradiation—that istosay, itisthetemperature (orasuitable average ofthetemperatures) ofwhatever would absorb energy radiated bythe antenna asatrans- mitter. This hasindeed been demonstrated experimentally. Ithasbeen shown 1that amicrowave antenna pointed atthesky receives only avery small amount ofradiation, corresponding toanabsolute temperature of atmost afew degrees. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.96x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 from 3–15 km. 
 B. H. Cantrell and G. 
 Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation.  THE PROPAGATION FACTOR, FP, IN THE RADAR EQUATION  26.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 to be on the leeward side of land masses and may occur both during the day and at  night. In addition, surface-based ducts may extend over the ocean for several hundred  kilometers and may be very persistent (lasting for days). 
 1525–1538, 1971. 26. C. 
 Also included in the MTD implementation are “…area thresholds maintained  to control excessive false alarms, particularly from bird flocks. Each area of about  16 square nautical miles is divided into several velocity regions. The threshold in each  region is adjusted on each scan to achieve the desired limit on false alarms without  raising the threshold so high that small aircraft are prevented from being placed in  track status.”4 In subsequent sections, specific aspects of the design of an MTD system will be  discussed. 
 Carlson: Comparative Evaluation of Stereo Radar Techniques Using Com­ puter Generated Simulated Imaginary, IEEE NAECON '74 Record, pp. 220-227, 1974. OTHER RADAR TOPIC'S 567  14. 
  OSCILLATOR ,/  FREQUENCY -ORE THAN ONE CONVERSION STAGE MAY BE NECESSARY TO REACH THE FINAL )& WITHOUT ENCOUNTERING SERIOUS IMAGE 
 BAND N 
 Applications of these methods appear inthefollowing descriptions. TheUseofSeries Rectifiers.-Figure 13.47 illustrates those parts that must beadded tothe sweep generator and amplifier ofFig. 13.44 to produce acomplete PPI involving theuseofdisk rectifiers. 
 43.Rigden.C.1:HighResolution LandClutter Characteristics, lEEConf.Pub/.No.lOS,Radar-- Prcscnt(lIIdflltl/re,London, Oct.23-25,1973,pp.227-232. 44.Valcl1Z~la, G.R..andM.B.Laing:Point-Scatlerer Formulation ofTerrainClutterStatistics, Naral Researc11 La!Joratory Report7459,Sept.27,1972,Washington, D.C. 45.Warden, M.P.:AnExperimental StudyofSomeClutterCharacteristics, AGARD C01!(Proc.no.66 OilAdrllllced RadarSystems, November. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°x£ SPACE 
 Nickel (FGAN, Germany), Prof. L. Chisci,  Dr. 
 The ability of a transistor to demonstrate high power output is impacted by the  breakdown voltage, the current capability, and the knee voltage of the transistor. Silicon device types cost-effectively satisfy the requirements of reliability, elec - trical performance, packaging, cooling, availability, and maintainability at lower  radar-band frequencies, typically UHF, L band, and into S band. These devices   are usually manufactured as discretely packaged transistors and require external  impedance-matching circuitry in order to function appropriately in an amplifier. 
 (ilasoe. G. N .. 
 RANGE AIR TRAFFIC  CONTROL SUCH AS !232 
 R. Meeker, and A. H. 
 61. Pettengill, G. H.: Radar Astronomy, chap. 
 TO 
 PLEX PROPAGATION CONSTANT F     GA   IK IA   WHERE  F   PROPAGATION CONSTANT  K   WAVE NUMBER O  K   @   ATTENUATION CONSTANT ;NEPERSM=  A   PHASE CONSTANT ;RADIANSM=. Ó£°n  2!$!2 (!.$"//+  4HE FIELD AT A DISTANCE Z FROM THE SOURCE IS GIVEN BY   %ZT % E EZJ TZ      
 BEAM JAMMERS  AND OTHERS PROVIDE BENEFITS AGAINST SIDELOBE JAMMERS "LANKING OR TURNING OFF THE RECEIVER WHILE THE RADAR IS SCANNING ACROSS THE AZI 
 The autofocusing result indicates that the existing scintillation mitigation method does not work perfectly even in moderate scintillation condition. As is mentioned before, the MS interferometric method [ 5] shed some new light on the mitigation of ionospheric scintillation, especially for sliding spotlight mode with large squint angle variations. (a)( b) Figure 12. 
 2AO ,OWER "OUND #2,"  ANALYSIS AND -ONTE #ARLO  SIMULATIONS  n   )N THESE STUDIES  IT IS SHOWN THAT THE SHAPE OF THE  5 FUNCTIONAL   e  (ERE  JUST ONE JAMMER IS CONSIDERED BUT THE MATHEMATICAL APPROACH IS EASILY EXTENDED TO MORE THAN ONE JAMMER.   %,%#42/.)# #/5.4%2 
 The basic structure of the classical form of the magnetron is shown  in Fig. 6.1.4 The anode (1) is a large block of copper into which are cut holes (2) and slots (J).  The holes and slots function as the resonant circuits and serve a purpose similar to that or the  lumped-constant LC resonant circuits used at lower rrequencies. 
 Astabilizer may generally bebroken down into three main com- ponents: the gyroscope lvith itspotentiometer orsynchro take-offs, the 1‘~hetheorv andInethods ofstabilization mediscussed inVol.26ofthisseries 2ByF.B.Lincoln.. 306 ANTENNAS, SCANNERS, ANDSTABILIZATION [SEC. 9.17 servoamplifier, and thefollow-up system which includes theservomotor, the gear train orlinkage system, and atake-off actuated bythe con- trolled member. 
 The echo signals for each interpulse  period can be stored in the digital memory with reference to the time of transmission. This  allows more elaborate stagger periods. The flexibility of the digital processor also permits more  freedom in the selection and application of amplitude weightings for shaping the filters. 
 DOPPLER 
 After passing through these two switches, the transmitter pulse travels down the r-fline tothe antenna, where itisradiated. The. 8 INTRODUCTION [SEC. 
 TIME MAP OF POWER REQUIRED  RELATIVE TO A  02%& OF  K7  TO DETECT A SPECIFIC  TARGET  AS A FUNCTION OF RANGE AND TIME 
 Thus, it causes targets to be missed. Furthermore, the operator is usually  given no indication that there may be missed detections. In radars with a simple CFAR,  interference or hostile jamming can lower the sensitivity of the radar without the operator even  being aware that it is happening since the jamming is not visible on the scope. 
 J. Geotech. Eng. 
 M. Headrick, and D. B. 
 In January 1947, a Joint Anti-Submarine School (JASS) was set up in Londonderry, Northern Ireland. The role of JASS was to run courses to train RN and RAF crews of ships and aircraft on the broader aspects of anti-submarine warfare. In the 1950s, JASS had a ﬂight of Shackletons for trials use, but this was disbanded in 1957. 
 STATE hMINIATUREv RADAR ALSO CALLED AN  ACTIVE APERTURE PHASED ARRAY   %ACH TYPE OF ANTENNA HAS ITS PARTICULAR ADVANTAGES AND LIMITATIONS 'ENERALLY  THE LARGER THE  ANTENNA THE BETTER  BUT THERE CAN BE PRACTICAL CONSTRAINTS THAT LIMIT ITS SIZE £°ÓÊ /9* 
 Reflections from nearby mountains and other large clutter can sometimes be of  such a magnitude that it is not practical to completely suppress their undesirable effects by  either MTI or range gating. One technique for reducing the magnitude of such large clutter . 498 INTRODUCTION TO RADAR SYSTEMS  seen by a fixed-site radar is to erect an !!lectromagnetically opaque fence around the radar (or  simply between the radar and the clutter source) to prevent the radar from viewing the clutter  directly. 
 This random change of phase can be  accommodated in a MTI radar receiver by use of a coherent oscillator (coho) as the  reference signal in the phase-detector stage of the receiver. On each pulse, the phase  of the magnetron pulse sets the phase of the coho. In this manner, the received signal  appears to be coherent pulse to pulse. 
 U. Nickel, “Superresolution and jammer suppression with broadband arrays for multi-function  radar,” Chapter 16 in Applications of Space-Time Adaptive Processing , R. Klemm (ed.), London:  IEE, 2004, pp. 
 DIMENSIONAL ACTIVE ARRAY OF  42 MODULES )T HAS A VARIETY OF MODES  FROM 3CAN3!2  
 ~Acollapsing lossdoesnottakeplacesincenoisefromtheotherrangeintervals is excluded. Ablockdiagram ofthevideoofanMTIradarwithmultiple rangegatesfollowed by clutter-rejection filtersisshowninFig.4.19.Theoutputofthephasedetector issampled sequentially bytherangegates.Eachrangegateopensinsequence justlongenoughtosample thevoltageofthevideowaveform corresponding toadifferent rangeinterval inspace.The rangegateactsasaswitchoragatewhichopensandclosesatthepropertime.Therangegates areactivated onceeachpulse-repetition interval. Theoutputforastationary targetisaseries ofpulsesofconstant amplitude. 
 The antenna waveguide ofthe other radar goes through in front and thedirectional coupler isput inthis convenient place. Inthe central section are the two duplexer sections and the two receivers. The duplexer section forthesearch radar stretches across the lower part ofthe case. 
 10.10b. Since the effective number of pulses integrated is equal to  (I - k)- ', a value of k = 0.9 corresponds to about 10 pulses integrated and k = 0.98 to about  50 pulses. However, when the recirculating-delay-line integrator is implemented with digital  circuitry, values of k approaching unity can be achieved.6s ,  The factor k in the recirculating-delay-line integrator of Fig. 
  INSTRUMENTATION RADARS USE THESE DETECTION PARAMETERS WITH   CONTIGUOUS RANGE GATES OF  YD EACH FOR ACQUISITION 4HE  GATES GIVE COVERAGE OF A  
 QUENCY 0ASSIVE MICROWAVE SOUNDING UNITS  HAVE MASS AND POWER RE QUIREMENTS ON THE  ORDER OF  KG AND  7  MUCH LESS THAN THEIR ACTIVE RADAR COUNTERPARTS 42-- 4HE 4ROPICAL 2AINFALL -EASURING -ISSION WAS A JOINT UNDERTAKING  BETWEEN .!3! AND THE *APANESE !EROSPACE %XPLORATION !GENCY *!8!  4HE FIVE 
 Small Arrays.  The element pattern is the best single indicator of impedance  matching in a scanning array. One way of determining the element pattern is to build  a small array. 
 I). N. Thomson, and J. 
 ,/" - 2EFLECTOR MECHANICAL DESIGN IS A DETAILED DISCIPLINE UNTO ITSELF WITH A MULTITUDE OF FACTORS TO CONSIDER &URTHERMORE  DESIGNS VARY SIGNIFICANTLY DEPENDING UPON MANY FACTORS  INCLUDING PLATFORM  REFLECTOR SIZE  ENVIRONMENT  FREQUENCY OF OPERATION  SCAN&/6  AND COST CONSTRAINTS !LTHOUGH IT IS NOT WITHIN THE SCOPE OF THIS CHAPTER TO ADDRESS MECHANICAL DESIGN IN DETAIL  A BRIEF SURVEY OF DESIGN FACTORS AND CONSIDERATIONS PRO 
 L,.,. : Same for L band.  i 'I', .J -I '"I>Ig~'\l '0I 'gI ~,,·1•'~I 'I'("/R Inl I ~-::I)" ! !=.~i~1 ""ff1 ,,,?P 1(\-. 
 POLARIZATION COMPONENT OF THE RADAR WAVE IN ADDITION TO THE COPOLARIZED COMPONENT 4HE TWO ORTHOGONALLY POLARIZED COMPONENTS CAN BE USED TO DISCRIMINATE THE USEFUL TARGET FROM CHAFF AND JAMMER ON THE BASIS OF THEIR DIFFERENT POLARIZATIONS   (OWEVER  LIMITED BENEFITS A FEW DECIBELS OF CANCELLATION RATIO  CAN BE OBTAINED AT THE EXPENSE OF A MORE COMPLEX ANTENNA SYSTEM CONSIDER  FOR EXAMPLE  A PHASED 
 FIELD  ( 
 1043–1047, 1956.  90. W. 
 /7", -Ê­ 
 Theoutputofthemonopulse radarisusedtoperform automatic tracking. Theangular­ errorsignalactuatesaservo-control systemtoposition theantenna, andtherangeoutput fromthesumchannel feedsintoanautomatic-range-tracking unit. Thesignofthedifference signal(andthedirection oftheangularerror)isdetermined by comparing thephaseofthedifference signalwiththephaseofthesumsignal.Ifthesumsignal Transmitter Hybrid junction 6 Difference channelPhase­ sensitlve detectorAngle­ error signalRange signal Figure5.8Blockdiagram ofamplitude-comparison monopulse radar(oneangularcoordinate).. 
 IJI.Sureau,J.c.:Conformal ArraysComeofAge,Microwal'l' J.,vol.16.pp.23-26,October, 197). 132.Giannini. R.1.,1.H.Gutman, andP.W.Hannon: ACylindrical Phased-Array Antenna forATC Interrogation, MicrowQl'e J.,vol.16,pp.46-49,October. 
 One of the characteristics of this mode of operation is that devices will continue to draw collector current as the amplifier is driven harder; consequently, there exists an optimum operating point with regard to RF drive level. This generally occurs as the transistor is driven approximately 0.5 to 0.75 dB into saturation. At the chosen operating point and under the conditions of fixed RF input drive and fixed dc supply voltage, amplifiers of this type also exhibit sensitivities of insertion phase and power output to changes in the input drive level, collector voltage, temperature, and load impedance.13 Some of the common sensitivities of a Class-C-biased amplifier are given in Table 5.3. 
 Further, output power isconsumed bythe rectifier- tube cathodes. Where anumber ofd-c output voltages are required, IInanycase, itisseldom practical toregulate thehighest-voltage output since current-limiting resistors arerequired intheregulator coilcircuit, andathigh voltages thelossinthem isexcessive. Itisalsolessimportant toregulate thehigher vcdtages, focthiscanreadily bedone byregulating circuits intheradar setitself.. 
 0ALMER EXPERIMENT AND THEIR RESULTING EXPONENTIAL DISTRIBUTION AND THE  MORE GENERAL THREE 
 583-585 Goldstein,3 p. 583 Wiltseetal.,4p. 226 Goldstein,3 pp. 
 MENTS BETWEEN SITES EG  MULTILATERATION  4HESE SYSTEMS USUALLY ARE NOT DESIGNED TO DETECT AND PROCESS THE ECHOES FROM TARGETS ILLUMINATED BY THE TRANSMITTER 4HEY CAN  HOWEVER  BE USED BY A BISTATIC HITCHHIKER TO IDENTIFY AND LOCATE A SUITABLE TRANSMITTER 4HUS  ALTHOUGH THEY HAVE MANY REQUIREMENTS AND CHARACTERISTICS  COMMON TO MULTI 
 This is typically accomplished with a contiguous bank of doppler filters  formed between two of the coherent pulse train’s spectral lines, one of which is the  central line. Range gating precedes the doppler filter bank. The bandwidth of each  doppler filter is inversely proportional to the duration of the coherent pulse train that  is processed to form the doppler filter bank. 
 BEAM VOLTAGE )T IS USUALLY EASIER TO DESIGN A DEPRESSED COLLECTOR FOR A 474 THAN FOR A KLYSTRON SINCE THE SPENT ELECTRON BEAM OF A 474 MIGHT HAVE A  SPREAD IN VELOCITY  BUT THE KLYSTRON MIGHT HAVE A VELOCITY SPREAD OF ALMOST   "ECAUSE THE EFFICIENCY IN A CONVENTIONAL 474 IS  USUALLY LOWER THAN THAT OF A KLYSTRON  THE INCREASE IN EFFICIENCY IN THE 474 PROVIDED BY A DEPRESSED COLLECTOR HAS A GREATER RELATIVE EFFECT THAN WITH A KLYSTRON.   4(% 2!$!2 42!.3-)44%2   £ä°££ 6ARIANTS OF THE +LYSTRON AND THE 474  )T WAS MENTIONED THAT THE BANDWIDTH OF  A KLYSTRON INCREASES AS ITS POWER IS INCREASED 4HE BANDWIDTH CAN ALSO BE INCREASED BY  COMBINING THE BEST FEATURES OF THE KLYSTRON AND THE TRAVELING WAVE TUBE TO OBTAIN BETTER BANDWIDTH  EFFICIENCY  AND GAIN FLATNESS THAN EITHER THE CONVENTIONAL KLYSTRON OR THE 474 )N THESE TUBES  THE BASIC STRUCTURE IS THAT OF A KLYSTRON  BUT INSTEAD OF A NUMBER OF SINGLE CAVITIES BEING USED  THE SINGLE CAVITY IS REPLACED BY A MORE COMPLEX MULTIPLE CAVITY 4HREE SUCH VARIANTS ARE THE  4WYSTRON   EXTENDED INTERACTION KLYSTRON   AND THE  CLUSTERED CAVITY KLYSTRON -OST HIGH 
 MENTED IN THE CONCEPT DEFINITION STAGE BEFORE PRODUCTION DECISIONS HAVE BEEN MADE 2ADAR 
 - !IR 
 SCAN PULSE 
 80. J. Asenstorfer, T. 
 SIDELOBE  HIGH 
 NAS OPERATED IN CLOSE PROXIMITY TO THE GROUND  THEN BOTH  SAFT  AND SART  ARE VARIANT WITH  &)'52%    #OORDINATE  SYSTEM  FOR  SCAN  DESCRIPTION  #OURTESY )%%                     . Ó£°ÎÓ  2!$!2 (!.$"//+  CHANGES IN THE GROUND SURFACE ELECTRICAL PARAMETERS %SSENTIALLY THE IMPEDANCE OF THE  ANTENNA IS CHANGED BY ITS PROXIMITY TO THE GROUND HENCE IT CANNOT BE CONSIDERED TO HAVE A STABLE IMPULSE RESPONSE !NY PROCESSING SCHEME THAT RELIES ON INVARIANT ANTENNA PARAMETERS SHOULD TAKE INTO  ACCOUNT THE MODE OF OPERATION OF THE ANTENNAS AND THE DEGREE OF STABILITY THAT IS PRAC 
 and J. W. Tukey: An Algorithm for the Machine Computation or Complex Fourier  Series. 
 This is accomplished  in a r.cPpcJ~rrcrr. ictnrrrrrr.. I)claying tlic rctrans;i~ission causes tlie repeated signals to appear at a  range and,/or ajlinlutli diffc~etit fro111 that of the jammer. 
 228 THEEMPLOYMENT OFRADAR DA1’.4 [SEC. 75 from this point. The detailed control offighter interceptors was carried out from group and sector headquarters, where plots were maintained on thebasis ofinformation repeated from Fighter Command Headquarters. 
  00 0.! ASS HF  &)'52%   3IDELOBE LEVEL TO BE HELD WITH PROBABILITY 0 AFTER * , !LLEN  . 
 Except for the sphere, whose  geometric-optics RCS is shown by the uppermost trace, all the objects have the same  nose angle (40°), and of the six shapes, the ogive exhibits the lowest RCS. Thus, at  least along the axes of these particular bodies, the RCS can be minimized by selecting  the appropriate surface profile. However, the attainment of low echoes over a range of aspect angles is usually  accompanied by higher echo levels at other angles. 
 This waveform does not result in ambiguities since there  is only one peak, but the single peak might be too broad to satisfy the requirements of  accuracy and resolution. The peak might be narrowed, but in order to conserve the volume  under its surface. the function must be raised elsewhere. 
 Moore, “Compact range techniques and measurements,”  IEEE Trans ., vol. AP-17, pp. 568–576, September 1969. 
 Sherman, and F. C. Ogg: Statistically Designed Density-tapered Arrays, IEEE  Trans., vol. 
 Steinhardt, and S. Stoner, “Least squares adaptive processing in military applica - tions,” IEEE Signal Processing Magazine , vol. 19, no. 
 7.25, is widely used when fan beams are  desired.  Another means of producing either a symmetrical or an asymmetrical antenna pattern is  with the parabolic ~ylinder.'.~.'~ The parabolic cylinder is generated by moving the parabolic  contour parallel to itself. A line source such as a linear array, rather than a point source, must  be used to feed the parabolic cylinder. 
 CONTROLLED RECTIFIER THYRISTORS AND &%4S ARE ALSO USED &%4 MODULATORS ARE SOMETIMES DRIVEN DIRECTLY BY A PULSE INPUT RATHER THAN A 0&. &INALLY  A PULSE TRANSFORMER MATCHES THE 0&. TO THE IMPEDANCE SEEN AT THE MAGNETRON CATHODE  ! PULSE OF AROUND  K6 IS REQUIRED TO FIRE  THE MAGNETRON )N ORDER TO GET GOOD PERFORMANCE OVER A WIDE RANGE OF PULSE LENGTHS  DESIGNS UTILIZE A GREAT DEAL OF EMPIRICALLY DERIVED KNOWLEDGE  AND ACTUAL CIRCUITS CAN BE SURPRISINGLY COMPLEX !  NS PULSE HARDLY ACHIEVES ANY PERIOD OF STABILITYRISE TIMES ARE NORMALLY RESTRICTED TO ABOUT   NS IN ORDER TO LIMIT  OUT 
 BASED 3!2 FIELD  hLOOKSv REFER TO STATISTICALLY INDEPENDENT VERSIONS OF THE SAME SCENE  7HEN THESE ARE ADDED TOGETHER  THE NET RESULT IS TO REDUCE THE SPECKLE NOISE  WHILE REINFORCING THE IMAGED FEATURES %ACH SUCH LOOK IS FORMED FROM A SPECTRAL BAND THAT DOES NOT OVERLAP SPECTRA CORRESPONDING TO THE OTHER LOOKS 4HUS  FOR A GIVEN BAND 
 145-147, 1983. 4. Scares, R., J. 
 2 'vi2t/t() (2.29) wheretheerrorfunction isdcfincd as 2r7.erfZ=-7:e-u2du V1t·o 1\graphic illustration oftheprocessofthreshold detection isshowninFig.2.6.The prohahility dcnsityfornoisealone[Eq.(2.21)]isplottedalongwiththatforsignalandnoise [Eq.(2.27)]withANb!2=3.Athreshold voltageVTNlP =2.5isshown.Thecrosshatched areatotherightofVTNlPunderthecurveforsignal-plus-noise represents theprobability of detection. whilethedouhle-crosshatched areaunderthecurvefornoisealonerepresents the prohability ofafalsealarm.IfVTNbl2isincreased toreducetheprobability ofafalsealarm, theprobability ofdetection willbereduced also. Equation (2.29)maybeusedtoplotafamilyofcurvesrelating theprobability ofdetection tothethreshold voltageandtotheamplitude ofthesine-wave signal.Although thereceiver designer preferstooperate withvoltages, itismoreconvenient fortheradarsystemengineer to employ powerrelationships. 
 Daley, “Wind dependence of radar sea return,” J. Geophys. Res ., vol. 
 The curves of Fig. 2.9 apply to a lossless antenna that has no part of its pattern directed toward a warm earth. The lossless condition means that the curves rep- resent only the noise received from external radiating sources. 
 As shown in Figure 9, CT2 was located in the bottom, relatively stable area, and the corresponding time-series deformation obtained through 242. Sensors 2019 ,19, 3073 both models are shown in Figure 10b. Due to the relatively low residual phase component in the linear model and the low rheological deformation component estimated in the rheological model, the results for the two models at CT2 were consistent during the period of June 2014 to August 2015, with a maximum diﬀerence of only 7 mm, and a maximum subsidence of 32 mm for the rheological model. 
 TO 
 Although the purpose of testing often governs how the measure- . CHAPTER 12 GROUND ECHO Richard K. Moore The University of Kansas 12.1 INTRODUCTION Radar ground return is described by a°, the differential scattering cross section, or scattering coefficient (scattering cross section per unit area), rather than by the total scattering cross section a used for discrete targets.! Since the total cross sec- tion a of a patch of ground varies with the illuminated area and this is determined by the geometric radar parameters (pulse width, beamwidth, etc.), a° was intro- duced to obtain a coefficient independent of these parameters. 
 CURRENT INTERAC 
 14.3ELECTRONIC COUNTER-COUNTERl\'lEASURES Allradars.civilianandmilitary, mustbeabletooperate inthecrowded electromagnetic environment thatresultsfromthetransmissions ofotherradiating sources. bothintheradar's ownbandaswellasfrom.outside theband.50Theradarmustbedesigned torejectthese unwanted radiations andtominimize thelikelihood ofitsowntransmissions causing trouble tootherusersofthespectrum. ThisisthesubjectofEMC,orelectromagnetic compatihility. 
 DOPPLER FOR TWO MEASUREMENTS AND  MULTIPLE 
 (8.3 )] it was assumed that the  elemental radiators were independent of one another. In practice this is only an approxima­ tion. Electromagnetic radiation doesn't always respect such an assumption. 
 Radars that rely on the doppler effect to enhance target detec - tion are called doppler radars .1 The doppler effect manifests itself when there is   a relative range rate, or radial velocity, between the radar and the target. When the  radar’s transmit signal is reflected from such a target, the carrier frequency of the  return signal will be shifted. Assuming a monostatic radar (i.e., collocated transmit - ter and receiver), the roundtrip distance is twice the distance between the transmitter  and the target. 
 The pulse-compression radar,  although widely used as a substitute for a short-pulse radar, has some limitations of its own,  as will be discussed later in this section.  EXTRACTION OFINFORMATION ANDWAVEFORM DESIGN421 compresses thelongpulsetoaduration 11H,whereBisthemodulated-pulse spectral band­ width.Pulsecompression isattractive whenthepeakpowerrequired ofashort-pulse radar cannotbeachieved withpractical transmitters. Application ofshortpulsetoradar.Aconventional short-pulse radarmaybedesiredforthe following purposes: Rallge resolutioll. 
 There- fore, ifthegain isreduced tothepoint required bystrong clutter, itwill betoolow forregions ofless ornoclutter, and wcafi signals ~rill still be lost. The IAGC circuit previously described is~’ery ~aluable under such conditions and has been included inmany receivers primarily forthis reason. Inthecase ofseareturn, theclutter isfairly constant atallazimuths. 
 NewYork,1970. 27.Ryall.D.W.G..andJ.Wild:PresentandFutureRadarDisplayTechniques, International Conf.on Radar- I'resental/(IFlllllre,Oct.23-25,1973,pp.201-206, lEEConference Publication no.105. 28.Lawson, J.L.,andG.E.Uhlenbeck: "Threshold Signals," vol.24,M.I.T.Radiation Laboratory Series. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.996x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 The loss in peak gain for this example, due to the boost of coverage at high angles,  was about 2 dB. 
 A. Soofi, and S. M. 
 Itoh, T.; Sueda, H.; Watanabe, Y. Motion compensation for ISAR via centroid tracking. IEEE T rans. 
 Fox, G. A., S. E. 
 §S PULSEWIDTH   
 END ATTENUATION IS THAT IT WILL TYPICALLY HAVE A LARGER IMPACT ON RECEIVER NOISE FIGURE THAN ATTENUATION PLACED LATER IN THE RECEIVER 4HIS IS NOT USUALLY AN ISSUE WHEN THE INTENT OF ADDING ATTENUATION IS TO DESENSITIZE THE RECEIVER AS IS THE CASE FOR 34# "ACK 
 JAMMING SIGNALS INTO THE RADARS SIDELOBES -ANY RADARS EMPLOY THE 3," SEE 3ECTION   TO DEFEAT THIS TYPE OF %#- 4RUE 
 IEEE T rans. Neural Netw. 1999 ,10, 988–999. 
 The clutter spec- trum will extend into more of the filter passband, and the improvement factor will be degraded. Figure 16.7 shows the improvement factor for single- and double-delay can- celers as a function of the ratio of the notch-offset error to the pulse repetition frequency (PRF) for different clutter spectral widths. Fortunately, the platform- motion spectrum is narrow in the forward sector of coverage where offset error is 0Vf r FIG. 
 At the high elevation an- gles, however, the echo power becomes independent of range and varies instead with the inverse fourth power of the altitude. An STC characteristic that is cor- rect for the low-angle radar echoes restricts high-angle coverage. This incompat- ibility of the STC requirements at the elevation extremes severely limits the use- fulness of STC. 
 Krolik, “Robust altitude estimation for over-the-horizon radar using  a state-space multipath fading model,” IEEE Trans. AES , vol. 39, pp. 
 MATED BY THAT OF TWO CROSSED CYLINDERS  PERMITTING THE CORRECTION TO BE APPLIED SIMPLY  WITH ROW 
 PULSE IF DESIRED 4HIS SECTION DESCRIBES SEVERAL OF THE TECHNIQUES COMMONLY USED TO GENERATE THE RADAR TRANSMIT SIGNAL DIGITALLY $IRECT $IGITAL 3YNTHESIZER $$3   &IGURE  SHOWS A BLOCK DIAGRAM OF THIS  TECHNIQUE  IN WHICH A NUMERICALLY CONTROLLED OSCILLATOR .#/  GENERATES A DIGITIZED SINUSOID THAT IS CONVERTED TO AN ANALOG SIGNAL BY A DIGITAL 
 6.1 Beam Scanning and Target Tracking  .................  6.1 Height Finding  ...................................................  6.2  Classification of An tennas  .................................. 
 ALARM RATE IN AN AUTOMATIC TARGET DETECTION !4$  SYSTEM !GAINST SPATIALLY HOMOGENEOUS SOURCES OF CLUTTER SUCH AS RAIN   SEA CLUTTER  OR CORRI 
 Theimage-recovery mixerrepresents· apractical compromise whichtendstobalance its slightlygreaternoisefigurebyitslowercost,greaterruggedness, andgreaterdynamic range.l.l Utilityoflow-noise front-ends. Thelowerthenoisefigureoftheradarreceiver, thelessneedbe thetransmitter powerand/ortheantenna aperture. Reductions inthesizeofthetransmiuer andtheantenna arealwaysdesirable iftherearenoconcomitant reductions inperformance. 
 21  4.3 Direction (Azimuth, Elevation )....................................................................................... 21  4.4 Polarization Characteristics of the Target ....................................................................... 21  5 Resolution and Accuracy ...................................................................................................... 
 However, a monopulse  antenna with a uniform illumination for the sum-pattern will have a poor difference-pattern,  even if the high sidelobes can be tolerated. A compromise must be made, and something other  than a uniform illumination is generally selected.  Thus the parameter of aperture efficiency, which sometimes is held sacred by thc anteillla  designer and to some who write antenna specifications, is often ofsecondary importance to the  systems engineer wishing to optimize total radar performance. 
 A popular way to solve this problem is data augmentation, such as ﬂipping, brightening, and contrast [ 30]. Another way to solve this problem is transfer learning, which often been applied in natural images [ 31]. The application which using deep neural networks in SAR ship images worth paying attention in improving the performance in SAR ship detection and classiﬁcation. 
 32. G. Franceschetti and R. 
 STATE TRANSMITTER )TS OVERALL RADAR PERFORMANCE WAS SIMILAR TO THE !32 
 VCOs can be used to create a tunable LO but are usually  phase locked to another stable source for improved stability. The tuning voltage design  and filter capacitor technology used to achieve phase lock must be carefully designed  to ensure rapid voltage and stored charge transitions. Otherwise, the VCO may properly  acquire and achieve phase lock, but the residual voltage decay from the transition will  manifest itself in an insidious phase ambiguity called post-tuning drift . 
 SITE FENCE  IN 3OUTH 4EXAS WAS DEPLOYED TO EVALUATE THE USE OF BISTATIC RANGE MEASUREMENTS TO IMPROVE LOCATION ACCURACY   BUT IT NEVER ENTERED CONTINUOUS OPERATION&)'52%   2EAL 
 A. Wilmot: Bird Strike and the Radar Properties of Birds,  l11tcmt1tio11c1I Co11( 011 Rc1dc1r l'resellf a11d Future. Oct. 
 Ó{°xn  2!$!2 (!.$"//+  .,) .OISE ,IKE )NTERFERENCE /4( /VER 4HE (ORIZON 0!2 0HASED 
 Ó£°£ÀÕ`Ê*iiÌÀ>Ì}Ê,>`>À  >Û`Ê >iÃ %2! 4ECHNOLOGY Ó£°£Ê  /," 1 /"  4HE TERMS  GROUND PENETRATING RADAR '02   GROUND PROBING RADAR  SUBSURFACE RADAR   OR SURFACE PENETRATING RADAR 302   REFER TO A RADAR 
 J. M. Stiles and K. 
 %RROR 2EDUCTION  6ERY 
 P. Langleben, and K. L. 
 SPACE-BASED REMOTE SENSING RADARS  18.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 as from the three-day repeat orbit first used with Seasat data to prove the concept and  for stable terrain features, such as unvegetated rocky mountain slopes. It is not neces - sarily satisfied for scenes, such as ice or vegetation, that may undergo changes in the  details of reflection and scattering between observations. In certain natural and most urban scenes, there will be many corner-reflector-shaped  features whose phase remains stable over very long time scales. 
 , 
 Classiﬁcation via sparse representation of steerable wavelet frames on Grossmann manifold: Application to target recognition in SAR image. IEEE T ran. Image Process. 
 CESSING 4HE FIRST &)2 FILTER  H N  PROVIDES SUFFICIENT REDUCTION TO PREVENT ALIASING  IN THE FIRST DECIMATION BY FACTOR  $  THE SECOND FILTER  HN  PROVIDES ALIAS REDUCTION  FOR THE SECOND DECIMATION AND CAN ALSO BE USED TO CORRECT PASSBAND RIPPLE OR DROOP DUE TO FILTER  H N  &OR LARGE DECIMATION FACTORS  MORE THAN TWO DECIMATION STAGES  MAY BE USED ! POPULAR FILTER FOR THE FIRST STAGE IS THE #ASCADED )NTEGRATOR #OMB #)#  DECIMA 
 Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 13.2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 The antenna beamwidth may be changed to search some areas more rapidly with less  gain. Frequency agility is possible with the frequency of transmission changing at will  from pulse to pulse or, with coding, within a pulse. 
 ................................ ..............  5  Ranging  ................................ 
 686 RADAR RELAY [SEC. 17.4 excluded bythe receiver. If,however, theseinterferingp ulsesarenottoo numerous and strong, itispossible toprovide almost complete protection against them byusing a“coded” signal torepresent the pulse, orby excluding allpulses that donot come within the narrow time interval which follows thelast useful pulse bytheknown repetition period, orby doing both. 
 Ill.WindForcesonStructures, ASCETrans.,vol.126,pI.II,paper3269,1961. 112.Hirst,H.,andK.E.McKee: WindForcesonParabolic Antennas, Microwave J.,vol.8,pp.43-47, November, 1965.. 113. 
 Two additional switching positions are needed to obtain the angular error in the ortho-  gonal coordinate. Thus a two-dimensional sequentially lobing radar might consist of a cluster  of four feed horns illuminating a single antenna, arranged so that the right-left, up-down  sectors are covered by successive antenna positions. Both transmission and reception are  accomplished at each position. 
 PERFORMANCE )NSTRUMENTED  !IRBORNE 0LATFORM FOR %NVIRONMENTAL 2ESEARCH (!)0%2  A 'ULF 3TREAM ' 
 JIO Jl5. March. 1960. 
 Clutter echoes or interference  from other electromagnetic radiations can also be minimized by adaptive antennas. Adaptive  antenna techniques can automatically compensate for mechanical or electrical errors in an  antenna by sensing the errors and applying corrective signals,149 and can compensate for  failed elements, radome effects, and blockage of the aperture from nearby structures. Much of  the interest in adaptive antennas has been to reduce the effects of noise jamming in the antenna  332INTRODUCTION TORADAR SYSTEMS Oneapproach istotryallpossibleelementlocations withthegivennumberofelements andselectthatarrangement whichproduces thebestresult.Thistechnique, calledlOtal l'lllllller(lIio/l, isgenerally impractical becauseofthelargenumberofpossible solutions that wouldneedtobeexamined. 
 1256,  September 1963. 24. L. 
 However, it also has the disadvantage that the thresholding is often ineffective.   The reason for this is that the mean -value calculation inevitably raises the threshold in the  neighbourhood of targets. Consequently, closely spaced targets can mask each other, partic u- larly if a small target is located close to a large  or extended target. 
 The types of guidance are inertial, map-following, command, beam-riding, and homing. Types other than inertial can use the broadest range of the electromagnetic spectrum, from radio frequen- cies (RF) through infrared (IR) to the visible spectrum and beyond, to perform the guidance function. Within these general categories, the surface-to-surface types [especially the intercontinental ballistic missile (ICBM) and the shorter-range ballistic] are usu- ally inertially guided and fall outside the scope of this discussion. 
 Thus the bistatic radar  does not .. overdetect" at short ranges as does monostatic radar.  The monostatic radar is well suited to volumetric coverage. 
 3PACE 34!0  4HE FIRST TYPE OF TRANSFORMATION TO BE CONSID 
    
 Brookner and R. J. Bonneau, “Spectra of rounded trapezoidal pulses having an AM/PM  modulation and its application to out-of-band radiation,” Microwave J ., vol. 
 POWE RED SYSTEM BETWEEN  A POINT 
 For a single look with Npdi CPIs noncoherently integrated and a specified PFA per  range-doppler cell, the Pd as a function of SNR for a Marcum (nonfluctuating) target  can be approximated as  P P N P Pd( , , ) . ln[ ( ) ] SNR erfcFA pdi FA FA = − − +1 20 8 4 1N NNNpdi pdipdiSNR21 2 21 2− − + −        (4.22) where erfc(·) is the complementary error function. The required SNR as a function of  Pd for a Marcum target is approximated as  SNRreqd FA pdi pdi pdipdi( , , ) P P NN NN d = + −η η22 21 4 (4.23) where  η= − − − − − 0 8 4 1 0 5 0 8 4 . 
 ss The magnitude of the error signal is a measure of the difference between the center  of the pulse and the center of the gates. The sign of the error signal determines the direction in . (al  ( b)  ( r) Echo I pulse  tor ly  gate  Early gate  signal L otr,  gate  L.ote gate  signal Time - Time -~  Time-+ TRACKING RADAR 177  Figure 5.17 Split-range-gate tracking. 
     
 a much wider range than the specified operating frequency band to ensure that the amplifier tube will remain stable. Signal-to-Noise Ratio. The noise power output of an amplifier tube may be significant. 
 of· transit time, of the scattered signal.  2. The angle of arrival of the scattered signal. 
 This method of modulation in which  tlie d-c anode-cathode voltage is applied contirluously and the tube is turned on by the start of  tl~c 1I.F tirive-prllse atid turrled olT at tllc ctlci of the pulse by tllc aid of a cut-OK electrode to  I crilovc t lie elect r 011s. Iias bee11 called ti-(. operrrtiort. 
 DC AND DC 
 In particular the conical  shape car1 presetit a serious polarization problem since the polarization varies with the direc-  t~on of propagation. Another problem is that the radiating elements can see different environ-  ments depending on their location on the cone. The pattern of the conical array cannot be  separated into elevation and azimuth patterns. 
 12.44  12.8 Imaging Radar Inte rpretation  ..................................  12.45  13. Sea Clutter   ............................................................... 
 There are two sets of radiators in the lens array requiring matching (the front and the  back), thus increasing the matching problem and the potential for lower efficiency. The feed  ~ ~ ~ >-------%-<  ; ~ ~ Array  ; ~ ~~ment --EA-----_--~-- ·---·--··-- I I  Primary 1  feed /  I I  :, r_:---"t -Phase ~ shifter  >----f?J-<  Figure 8.22 Principle of lens array. ()ff,,..,,  µr 1111or y  fped JI IF FllTTRONICi\U Y STITRFD Plli\SFD i\RRi\ Y i\NTENNi\ IN Ri\Di\R 309  I  f'lrtoy , I  I I I "/I'm Pr ii  \, ... 
 CFARisimportant since,without it,cluttercanexcitetheradardisplayand obscure thepresence ofdesiredtargetsevenifthetargetsareofgreaterstrength thanthe clutter.CFARprevents obscuration ofdetectable targetsbyweakerclutterbymaintaining theclutteroutputfromthereceiver ataconstant 'valuewellbelowthesaturation levelof thedisplay. Thisisespecially important intrack-while-scan, orautomatic detection and tracking (ADT)syste·ms, whereevensmallincreases inbackground cluttercouldresultin excessive falsealarmsthatoverload thecapacity ofthetracking computer. AswithanyCFAR, theconstant false-alarm rateismaintained attheexpenseoftheprobability ofdetection. 
 Iowe anapology toallthe authors forthe liberty Ihave often taken inaltering their original text tofitthe final framework ofthe book and myown ideas ofstyle. Because most authors lefttheLabora- tory immediately onfinishing their writing, and much ofthe editorial work had tobedeferred until thebook was substantially complete, ithas notalways been possible toadjust with theauthors thealterations intheir manuscripts that have seemed desirable tome. The general acknowledgments Iowe asEditor-in-Chief oftheSeries are setforth inthe Series Index. 
 In a dual-frequency surveillance and track radar performing an air traffic control (ATC) mission, as mentioned in Sec. 22.6, it is possible to trade off the length of the surveillance fence against the number of targets in track as functions of the track data rate and the radar-beam grazing angle. In a high-resoiution-mapping radar mission it is possible to trade off the resolution against the orbital altitude as functions of radar wavelength and integration time. 
 DIGITAL CONVERTER !$#  AND DIGITAL 
 ING MACHINE  USING THOUSANDS OF HIGH PERFORMANCE INTEGRATED CIRCUITS )#S  4HESE MACHINES WERE VERY DIFFICULT TO DESIGN  DEVELOP  AND MODIFY $IGITAL TECHNOLOGY HAS ADVANCED TO THE POINT WHERE SEVERAL IMPLEMENTATION ALTERNATIVES EXIST THAT MAKE THE PROCESSOR MORE PROGRAMMABLE AND  HENCE  EASIER TO DESIGN AND CHANGE 0ARALLEL 'ENERAL 
 23.2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 Bistatic target location uses a process different from that of a monostatic radar. In a  typical implementation, the bistatic radar measures (a) the transmitter-to-target-to-receiver  propagation time, converted to a transmitter-to-target plus target-to-receiver range-sum ;  (b) the target direction-of-arrival (DOA) from the receiver; and (c) the transmitter-to- receiver distance, or baseline , to solve the transmitter-target-receiver triangle, called the  bistatic triangle . This triangle locates the target, usually in terms of a range and angle  referenced to the receive site. 
 53. “Advanced stand alone prediction system,” IPS Radio and Space Services, The Australian Space  Weather Agency, http://www.ips.gov.au/Products_and_Services/1/1. 54. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas.  PHASED ARRAY RADAR ANTENNAS  13.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13  EN s N sa( )sin ( / )(sin sin ) sin ( / )(sinqq q q=− π λ π λ0 − −sin )q0 (13.7) and the pattern is  E EN s N se ( ) ( )sin ( / )(sin sin ) / )q qq q=− π λ π λ0 sin[( ( (sin sin )] q q−0 (13.8) Equation 13.8 describes the fundamental response of a scanned array system. The  array will have only one single major lobe, and grating-lobe maxima will not occur  for −90° < q < +90° as long as  πλπs| sin sin |q q− <0  or  s λ<+1 10 | sin |q (13.9) which is always true if s/l < ½. 
 14.1.) Furthermore, individual machines ofthe inductor-alternator type show wide variation incharacteristics. Crest factors measured for different machines ofagiven type have shown variations intherange from 1.15 to1.75. When power istobederived from analternator ofthis type, transformers forradar rectifiers should beprovided with primary taps, and filament supplies should beobtained from separate transformers. 
 TACTS GENERALLY REPRESENT TARGETS 2E 
 3 v $IG )'!233   PP n    ( (IROSAWA AND 9 -ATSUZAKA  h#ALIBRATION OF CROSS 
 FIELD ANTENNA PRINCIPLES ARE UTILIZED ! DESIRED APERTURE DISTRIBUTION FUNCTION IS SPECIFIED 4HE NEAR 
 No analogous method ofazimuth-pulse removal exists for aself- synchronous modulator. Itisusually satisfactory toremove thepulse by anticoincidence methods, even though a“hole” isleft inthevideo signal train. Otherwise, itwillbenecessary tointroduce between themodulator pulse and the basic pulse adelay which islonger than the useful video- signal interval and totransmit both pulses. 
 154. S. L. 
 - 4HE CHOICE OF A PULSE COMPRESSION SYSTEM INVOLVES THE SELECTION OF THE TYPE OF WAVE 
 Theeffectistomask theaircraft, muchlikeasmokescreen. Chaffisarelatively slowmoving targetcompared withaircraft. Itsvertical descent is determined bygravityandbythedragcharacteristics oftheindividual foilstrips,Itshorizon­ talcomponent ofvelocity depends onthewind.Chaffmaybedistinguished frommoving aircrafttargetsonthebasisofitsslowervelocity. 
 The parameter m varies between 0.3 and 2, depending on aspect. These have sometimes been  called Weinstock cases.  The chi-square distribution with m = 1 (Swerling cases 1 and 2) is the Rayleigh, or  exponential, distribution that results from a large number of independent scatterers, no oric of  which contributes more than a small fraction of the total backscatter energy. 
 Meadows, and P. A. Matthews: Layer Structure of the Troposphere,  I'roc. 
 CryoSat is described in more detail in a subsequent section. AltiKa . AltiKa differs from other ocean-viewing altimeters in this section, due  primarily to its use of Ka band (35.75 GHz) rather than Ku band. 
 Common discretes are affected by the time-delay between the portion imparted  on the transmit and that on receive. The time-delay changes the correlation between  the phase of the spurious modulating frequency from the transmit path with the phase  from the receive path.54 This can relieve the common discrete level requirement for  low-PRF (or MTI) waveforms that are range unambiguous. However, for highly range  ambiguous medium-PRF and high-PRF waveforms, the assumption is made that the  noise common to transmit and receive adds noncoherently in the downconversion  process. 
 This property of“supernormal” buildup was atone time believed tobevery desirable from the signal- discernibility standpoint, onthe hypothesis that itwould give the repeating signal anadvantage over random noise. However, theprop- erty ismost exaggerated onaninitially unexcited screen, whereas in actual cases ofsuccessive scan integration the screen isinitially excited from previous scans. Furthermore, itisnot evident apriori that the 1When extended observations aretobemade cmasingle target orregion the display issometimes “frozen”; th~t is,thetarget motion relative totheradar iscom- pensated sothat thepicture remains stationary. 
 Ashutter issho\vn across one ofthewaveguides in the position itoccupies when the transmitter isoff. This shutter pro- vides crystal protection against signals picked uponthe antenna when theTR switch isnotfiring. At~heother end ofthereceiver areavideo- output jack and aterminal strip forbringing inpower and certain control voltages. 
 You can use pocket calculator, but  the chosen here numerical examples are optimized to perform with mental arithmetic.     1. Specify the flow of radar signals from the originating device in given radar set to the users  display!              2. 
 BEAM #7 
 There are also penalties from (i) filter switching time, (ii) set - tling time, (iii) distortion caused by group delay dispersion, and (iv) reduced reliability  when there are hundreds of receivers. Further, each channel will need to account for  the gain and phase variation for each filter, increasing the overheads on band switch - ing. It is better to zero in on the bandwidth of interest by nonswitched filters later in the  receiver, using a variable frequency local oscillator to position the desired subband(s)  over the selective filters. 
 Nevertheless,  agreement between measurement and prediction of the type illustrated in Figure 15.19  FIGURE 15.19  Comparison of the predictions of the Bragg hypothesis with NRL  4FR data (heavy lines) for higher wind speeds ( > 22 kt): dash-dotted lines, SPM  Bragg; dashed line, two-scale model for H-polarization only, assuming 10° mean  sea slopes ( after Valenzuela102) ch15.indd   31 12/15/07   6:17:18 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter. 
 Kielsy, “Parabolic cylinder aerials,” Wireless Eng ., vol. 28, pp. 73–78, March 1951. 
 TYPE RADIA 
 Relatively thin absorbers, however, can be obtained with magnetic materials  having appropriate dielectric proper tie^.^^.'^^.'^^  14.6 BISTATIC  RADAR^'.^^  Throughout this book, it has been assumed that a common antenna is used for both transmit-  ting and receiving. Such a radar is called ntotlostatic. A bistatic radar is one in which the  tranqrnitting arid receiving aritenrlas are separated by a considerable distance (Fig. 
 630-643, May, 1937.  75. Block. 
 ATING AT n VOLTS  ONE CAN EXPECT TO DELIVER n 7MM OF NORMALIZED POWER OUTPUT DENSITY 4HUS  TO ACHIEVE A POWER LEVEL OF  WATTS AT   '(Z  WHEN OPERATING  FROM  VOLTS  APPROXIMATELY  GATE FINGERS MUST SOMEHOW BE COMBINED IN PARALLEL TO  &)'52%   #ROSS SECTION OF A  §M DOUBLE GATEnRECESSED 'A!S  0(%-4 TRANSISTOR  SHOWING GATE  DRAIN  AND SOURCE METALS 0HOTOGRAPH  COURTESY OF 2AYTHEON #OMPANY  .   3/,)$ 
 AR 9^o FIG. 17.23 Generalized 85 percent cumulative probability of detection for scan-to-scan, Swerling Case 1, Rayleigh fluctuating target. The constants a and b can be found by substitution, using two pairs of Pd and gRIR0 values from Fig. 
 Note the  duct, identified by the dashed line, contains the trapping layer and “normal” gradient  layer below. The third type of surface duct is one created by a rapid decrease of relative  humidity immediately adjacent to the air-sea interface. This duct is referred to as an  evaporation  duct. 
 This rules out frequently used  nonreciprocal ferrite or garnet phase shifters. Constrained Feeds.  The optical-feed system divides power very simply in one  step from the feed to the many elements on the aperture. 
 3ANDWICH 4HE # 
 PULSE BINOMIAL CANCELER   PULSE 
 BASED DUCT MAY SLOPE UPWARD TO BECOME AN ELEVATED DUCT AS WARM  DRY CONTINENTAL AIR GLIDES OVER COOL  MOIST MARINE AIR 4HE TRADEWIND INVERSION MAY ALSO INTENSIFY  THEREBY TURNING AN ELEVATED DUCT INTO A SURFACE 
 These skewing and spreading effects, along with increased clutter levels, can greatly complicate the ability of a bistatic radar to detect targets in clutter. Rem- edies include conventional doppler filtering and high time-bandwidth waveforms; the judicious use of masking when available; control of the geometry, especially when a dedicated or cooperative transmitter is available; design of very low re- ceive (and transmit when possible) antenna sidelobe levels; sidelobe blanking of discrete clutter returns; range or range-doppler averaging in the constant false- alarm rate (CFAR) unit for homogeneous clutter; and spatial excision of clutter returns. One implementation of this last technique relies on knowledge of the ge- ometry and kinematics to predict the clutter doppler and spread in a given area. 
 ITY OF RADAR OBSERVATIONS TO DYNAMICAL PROCESSES 4HIS ARISES PRIMARILY BECAUSE OF THE EXTREMELY HIGH DYNAMIC RANGE REQUIRED TO ACCOMMODATE AND PRESERVE TARGET ECHOES IN THE PRESENCE OF STRONG CLUTTER AND EXTERNAL NOISE )ONOSPHERIC 3TRUCTURE  4HE BASIC PHYSICS OF IONIZATION AND RECOMBINATION PRO 
 57. Barrett. R. 
 (7.14).  A(z) = { J_'xi~ E(q,) exp (-j2n I sin q,) d(sin </>) (7.14) . RADAR ANTENNAS 255  where z = distance along the aperture and E(</>) = field-intensity pattern. 
 OTHER RADAR TOPICS559 frequency aloneandtheradarhasnoMTIcapability. Also,thelocation ofthetargetposition fromthemeasurement ofthetotalscattered'path lengthSisindeterminate, asmentioned previously. Itisconcluded thattheconditions forobtaining thelargeforward-scatter signalaretoo restrictive tobeapplicable inmostradarsituations. 
 Because of the  mechanical and voltage-breakdown problems associated with this tuner, it is more suited for  use at the longer wavelengths. Either the cookie cutter or the crown-of-thorns mechanisms can  achieve a 10 percent frequency change. The two can be used in combination to cover a larger  tuning range than is possible with either one alone. 
 Y XY ZV XY H  WHERE X  Y  Z  ARE UNIT VECTORS (ENCE    V2VY XY HR      V2   WHERE VR IS THE RELATIVE SPEED #URVES OF CONSTANT RELATIVE SPEED ARE ALSO CURVES OF  CONSTANT DOPPLER SHIFT 4HE EQUATION OF SUCH A CURVE IS   XYVV VHR R  
 22] ANTENNA GAINANDRECEIVING CROSS SECTION 19 2.Noalternate transmission path, via areflecting surface, can be followed byasubstantial fraction oftheradiated energy. 3.The intervening atmosphere ishomogeneous with respect toindex ofrefraction, atthefrequency used. 4.The intervening atmosphere istransparent, i.e., does not absorb energy from thewave, atthefrequency used. 
 Inother words, once attenuation takes hold, itisoflittle avail tostruggle against it. 1J.IV.Ryde andDRyde, Report 8670 of‘~hc Research Laboratory ofCxeneral Electric Company, Ltd. ‘~his isaBritish publication.. 
 For thepurpose offirecontrol ngainst ships, arapid-scan precision radar ismost desirable, because the 1.imilisathousandth ofaradian; thus 17.4roils =1’. ?By1,.>-.Ridencmr.. SEC. 
 7. Krishnan, S.: Diode Phase Detectors, Electronic and Radio Engr., vol. 36, pp. 
 Grisetti, R. S., M. M. 
 J. B., and A. B. 
 ALIAS REJECTION REQUIRED TO PREVENT ALIASING IN THE DECIMATION OF THE )1 DATA RATE $IGITAL FILTERING CAN BE PRECISELY CONTROLLED  TAILORED TO ALMOST ANY DESIRED PASSBAND AND STOP BAND REJECTION REQUIREMENTS 4HE DIGITAL FILTERS USED ARE TYPICALLY LINEAR PHASE &)2 FILTERS  BUT THEY CAN ALSO BE TAILORED TO COMPENSATE FOR VARIATIONS IN THE PASSBAND PHASE AND AMPLITUDE RESPONSES OF 2& AND )& ANALOG FILTERS &ILTER #HARACTERISTICS  &ILTER RESPONSES ARE CHARACTERIZED FULLY BY EITHER THEIR  FREQUENCY RESPONSE  (V  OR THEIR IMPULSE RESPONSE  HT  HOWEVER  THEY ARE USUALLY  SPECIFIED BY A VARIETY OF PARAMETERS AS DESCRIBED BELOW $IGITAL FILTERS MAY BE SPECI 
 Consider a sinusoid modulated by a train of five pulses, each of width r.  The pulse-repetition perio~ is Tp, and the duration of the pulse train is T.i (Fig. 11.1 la). 
 For stationary targets  tlie dopplcr frequcrlcy sliift will be 'ero; Iience Vdirr will not vary with time and may take on  ariy coilstant value fr-on1 1- .I, to - ,(I,, ir~cluding zero. However, when the target is iii rtiotioii  relative to the radar, ,/* lias a value other than zero arid the voltage corresponding to tlie  dilTcr-cncc freqrrcilcy froin tlie inixer [Eq. (4.3)) will be a functioii of time. 
 IEEE T rans. Geosci. Remote Sens. 
   BANDWIDTH PRODUCT )F PULSE COMPRESSION IS DONE SUBSEQUENT TO THE !$ CONVERTER   THEN THE LIMITATION IS   )*" LOGT TD"    4HE  LIMITATIONS ON THE ATTAINABLE -4) IMPROVEMENT FACTOR ARE SUMMARIZED IN  4ABLE  4HIS DISCUSSION HAS ASSUMED THAT THE PEAK 
 chaff,anddecoys. Intercept receivers anddirection finders(whichare calledelectronic sl/pport meaSl/res, orESM),aswellasantiradiation missiles (ARM)arealso aspectsofelectronic warFare (EW)thatmustbeofconcern tothemilitary radarsystems designer. Ifadetermined adversary iswillingtopaytheresultant price,sufficient ECMcanbe brought tobearagainstanysingleradartosignificantly reduceitseffectiveness. 
 and Tech. , vol. 50, pp. 
 The nonlinear distortions of the available amplifiers can be usually  neglected.  In Figure 8.1d the signals in the time and frequency domain for non -coherent pulse . Radar System Engineeri ng Chapter 8 – Pulse Radar  50     Radar are  represented. 
 KNOWN -)4 2ADIATION ,ABORATORY BOOK MENTIONED ABOVE   5NFORTUNATELY  THE SCATTERING MODELS DEVELOPED DURING THIS PERIOD  ALONG WITH MOST OF THOSE PUBLISHED OVER THE FOLLOWING DECADE  FAILED TO ACCOUNT IN ANY CONVINCING WAY FOR THE BEHAVIOR OF SEA BACKSCATTER )N   HOWEVER  #ROMBIE OBSERVED THAT AT HIGH 
 Major new information about the Moon  was provided from Clementine ’s data collected during its 71 days in lunar orbit. Clementine  is relevant to this chapter because of a unique bistatic radar experiment  conducted with the S band (13.19 cm) RF data system. The lunar south pole was illu - minated by Clementine ’s communications antenna (6 watts, circularly polarized), and  the reflections from the specular point were tracked by an antenna of the Deep Space  Network (DSN) over four passes. 
  
 PULSE COMPRESSION RADAR  8.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 sidelobe levels measured on production hardware are –58 dB. Digital pulse compres - sion is used. An uncoded 1.1-µs pulse is used to provide coverage for targets within  the range interval from 0.5 to 5.5 nmi. 
 ISBN  978-3-03936-122-9  (Hbk)  ISBN  978-3-03936-123-6  (PDF) c/circlecopyrt2020 by the authors. Articles in this book are Open Access and distributed under the Creative Commons Attribution (CC BY) license, which allows users to download, copy and build upon published articles, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. The book as a whole is distributed by MDPI under the terms and conditions of the Creative Commonslicense CC BY-NC-ND.. 
 The radar contacts were  actually returns from land that had been ducted over the horizon. Several meteorological conditions will lead to the creation of ducts. Where these con - ditions exist and what these conditions are determines the name and nature of the duct. 
 */Ê"Ê 
 By placing the attenuation as close to the front end as possible, large  signals can be handled by minimizing gain compression, intermodulation, or cross- modulation distortion in the majority of receiver components. The disadvantage of  using front-end attenuation is that it will typically have a larger impact on receiver  noise figure than attenuation placed later in the receiver. This is not usually an issue  when the intent of adding attenuation is to desensitize the receiver as is the case for  STC. 
 Ó£°{ä  2!$!2 (!.$"//+  , 
 FREE RANGES AT THE END OF  EACH 02) 4HIS TECH 
 The limitations ofAIradar were such that a coordinated attack onasingle bomber bymore than one nightfighter was notpossible, and theonly practicable attack was thestern chase. Under I these circumstances, the bomber can beprotected byasimple, short- range radar equipment mounted inthe tail turret. The B-29 was equipped with aradar ofthis sort, theAN/APG-15. 
 Ruetz, “High-power linear-beam tubes,” Proc. IEEE ,   vol. 61, pp. 
 £°£Ó  2!$!2 (!.$"//+  MASS REACHED ABOUT  TO   THE ATTENUATION WAS ABOUT TWICE THAT OF A COMPLETELY  MELTED PARTICLE 4HESE CALCULATIONS SHOW THAT THE ATTENUATION IN THE MELTING OF ICE IMME 
 The spectrum  shown in Figure 16.10 is the spectrum of the envelope of samples at R1 (after low-pass  filtering). The spectrum of fading at another range (or vertical angle) is different, in  accord with Eq. 16.13. 
 For the worst case, over-the-shoulder geometry, the requirement would be  to match LOS coverage on the extended baseline, rT = rR + L, so that  L = 130 ( √hT - √hR) (23.7) For example, when hT = 0.1 km and hR = 0.01 km, L = 28 km, which from Eq. 23.5  and 23.6 will provide LOS to an 8.5 m altitude target flying above the extended  baseline, 25 km from the receiver and 53 km from the transmitter. Baselines greater  than 100 km can pose severe target LOS problems. 
 Introduction One important use of synthetic aperture radar (SAR) imagery is in detecting changes between datasets from different imaging passes. Target and coherent change detection in SAR images have been extensively researched [ 1–4]. In two-color multiview (2CMV) advanced geospatial information (AGI) products, the changes are colorized and overlaid on an initial image such that new features are represented in cyan, and features that have disappeared are represented in red. 
 32. Chen, Z.Q.; Li, C.; Sanchez, R.V . Gearbox fault identiﬁcation and classiﬁcation with convolutional neural networks. 
 2000 ,9, 1088–1093. [ CrossRef ][PubMed ] 7. Castillo-Rubio, C.F.; Llorente-Romano, S.; Burgos-Garcia, M. 
 OFFS ARE RELATIVE TO THAT STARTING POSITION ! RADAR HAVING AN INHERENTLY SMALL RANGE SWATH  FOR EXAMPLE  WOULD REQUIRE 3CAN3!2 TO EXPAND THE RANGE SWATH TO A FEW TENS OF KM  WHICH MAY STILL BE MUCH LARGER THAN THE SAME RADAR COULD COVER WITHOUT AMBIGUITIES IN A STRIP 
 96. R. A. 
 DICT  TYPICAL WAVEFORM VARIATIONS CAN BE TABULATED BASED ON OBSERVED BEHAVIOR OF A NUMBER OF EXISTING ! 
 X band is a suitable frequency  for civil marine radars, airborne weather avoidance radar, airborne doppler navigation  radars, and the police speed meter. Missile guidance systems are sometimes at X band.  Radars at X band are generally of a convenient size and are, therefore, of interest for  applications where mobility and light weight are important and very long range is not  a major requirement. 
 MARIZED IN &IGURE   4HE RESULTANT RMS SIDELOBES ARE REFERENCED TO THE GAIN OF A  SINGLE ELEMENT SO THAT THE CURVE CAN BE USED FOR ANY NUMBER OF  ELEMENTS WITH INDEPEN 
 The low-pass filter smoothes (or interpolates) the analog signal components  between waveform samples to provide the equivalent of a much higher waveform- sampling rate. The I(t) component modulates a 0 ° carrier signal, and the Q(t) compo - nent modulates a 90 ° phase-shifted carrier signal. The desired waveform is the sum of  the 0 °-modulated carrier and the 90 °-modulated carrier. 
 A failure in one channel does not require the radar to  shut down. The radar operates with a single channel while repairs are being made. The  availability of dual-channel radars with built-in-test equipment and fault isolation has been  demonstrated to be considerably greater than 99 percent. 
 This implies that both the receiver inthe beacon and the one inthe interrogating system have abandwidth suffi- cient toinsure that both received signals rise toavalue that depends on thepulse po\ver and isindependent ofthelength ofthepulse \vithin wide limits. This condition isusually the desired one and the receivers are designed accordingly. Ifareceiver ofvery narrow bandwidth should beused, however, thepeak value ofitsoutput would then depend upon the energy ofthe pulse, rather than upon the pulse power. 
 The true map is shown on the right, and comparison  can thus be made between this and the radar image of the  characteristic English coastline of the Wash.  Plate IV Op. 128). 
 TION REQUIREMENT MEANS THAT !$ CONVERTER CLOCK SIGNALS FOR EACH CHANNEL MUST BE ALIGNED IN TIME AND DECIMATION MUST BE PERFORMED IN PHASE FOR EACH CHANNEL 0HASE AND AMPLITUDE IMBALANCE BETWEEN CHANNELS IS A RESULT OF VARIATION IN THE  &)'52%  $ECIMATION USING POLYPHASE FILTERS                 . È°{È  2!$!2 (!.$"//+  ANALOG CIRCUITRY PRIOR TO AND WITHIN THE !$ CONVERTER )F THE )& FILTER BANDWIDTH IS  WIDE RELATIVE TO THE DIGITAL RECEIVER BANDWIDTH  THE MAJORITY OF THE ERROR BETWEEN CHANNELS WILL BE A CONSTANT GAIN AND PHASE OFFSET ACROSS THE RECEIVER BANDWIDTH ! SINGLE CORRECTION  APPLIED AS A COMPLEX MULTIPLICATION OF  )1 DATA  WILL COR 
 Onthe other hand, intensity modulation permits the presentation ofa two-dimensional figure onwhich the signals appear asbright spots or patches, but offers only qualitative information about signal intensity. The CRT screen cannot present any true three-dimensional picture, ofcourse; this isthe most fundamental limitation ofthe cathode-ray tube asaradar indicator. Under very simple conditions, itispossibl~ topresent athird dimension inanunderstandable though unnatural way, but inany complicated three-dimensional situation one isforced touse more than one display. 
 By analogy to the linear-FM pulse-compression waveform, the linearly varying doppler  signal can be passed through a matched filter to produce a pulse of duration 1/AJd. This  526INTRODUCTION TORADAR SYSTEMS frequency, calledthe~trsetfrequency, alongwiththedcbias.(Theoffsetfrequency isequalto thedoppler frequency shiftassociated withascalterer locatedattheedgeoftherealantenna beam.)Theresult,whichissimilartoreconstructing theimageofahologram, isthatthe desiredrealimagecanthenbeseparated fromtheenergyassociated withthebiasandthe virtualimage.Theslitisdisplaced fromtheopticalaxisattheplacewheretheoffsetfrequency focusestherealimage.Arecording filmintheoutputplaneP2,whenmovedwithaspeed proportional tothatofthevehiclecarrying theradar,produces amapofthesceneoriginally viewedbytheradar. Ifamplitude weighting ofthesynthetic apenure isdesiredtoreducethesidelobcs, a shadedtransparency withuniform phasethickness canheinserted adjacent tothedatafilmin planePI' Digital processing. 
 In short, fix the beams and let the  satellites fly through them. It has been in continuous use since 1958. A hitchhiker using a cooperative radar transmitter in the co-site region was the  Multistatic Measurement System  (MMS ). 
 +1/" Ê",Ê 
 However, the aspect dependent scattering recovery of it is not accurate. The subaperture images of WASAR can be regarded as the SAR video. The support set among the different frames of SAR video are highly overlapped. 
 .'."  Assume the form of the transmitted signal to be  A f 2?fo t + sin 2?fm t ? fm  where .fo = carrier frequency  ,fm = modulation frequency  Af= frequency excursion (equal to twice the frequency derivation)  The difference frequency signal may be written  L'D = Jo(D) COS (2?fdt - 40) + 2J1(D) sin (2?fdt - $0) COS (2?fmf - (6,,,)  - 2J,(D) cos (2?fd t - 40) cos 2(27rfmt - (6,)  - 2J3(D) sin (2~fdt - (60) COS 3(2?fm t - (6m)  -k 2J4(D) COS (2?fdt - (60) COS 4(2?fm 1 - (6,) + 2J5(D) '' '  88INTRODUCTION TORADAR SYSTEMS Figure3.14Unwanted signalsinFMaltimeter. (Frv/II Capelli,30 IRETrans.) (3.15)Transmitter leakage. Thesensitivity ofFM-CW radarislimitedbythenoiseaccompanying thetransmitter signalwhichleaksintothereceiver. 
 164–173,  April 1986. 150. G. 
 35. Bussgang, J. J., and D. 
 ÓÓ°£{  2!$!2 (!.$"//+  34# AND THRESHOLDING IS A PROCESS THAT IS CONTROLLED IN THE DIGITAL DOMAIN BUT OFTEN  APPLIES ANALOG GAIN PROCESSES AT 2& AND )& AT BOTH PRE 
 The solid curves are  exact valuescomputed by Haddock.71•72 The Rayleigh scattering approximation is seen to be  satisfactory over most of the frequency range of interest to radar.  The reflectivity factor Z of Eq. (13.19), which was defined as the sum of the sixth power or  the particles' diameter per unit volume, was based on the assumption of Rayleigh scattering. 
 W.henthefunction isperformed byelectronic decision circuitry without theinterventioll ofanoperator, theprocess isknownasmttomatic detection. Oneofthechiefreasons foremploying automatic detection istoovercome the limitations ofanoperator duetofatigue,boredom, andoverload. Inaddition, theuseof automatic detection allowstheradaroutputtobetransmitted overtelephone linesratherthan bymoreexpensive broadband microwave links,sinceonlydetected targetinformation needbe transmitted andnotthefullbandwidth signal(rawvideo).Automatic detection isalsoan important partofautomatic detection andtrack(ADT)systems, asdiscussed inSec.5.10.The automatic detector hasalsobeencalledplotextractor anddataextractor. 
  AND DOWNCONVERTERS  WHICH CAN BE UTILIZED IN RADAR SYSTEMS 4HE INTRODUCTION OF THE &IELD 0ROGRAMMABLE 'ATE !RRAY &0'!  IN THE S  HERALDED A REVOLUTION IN THE WAY REAL 
 A. Fabrizio, W. L. 
 A firm conclusion in favor of one  polarization or the other is difficult to make for a civil marine radar, but most sets use  horizontal polarization.21 At high sea states the difference between horizontal and vertical  polarization is said to disappear. 22  Horizontal polarization, as was mentioned in Sec. 13.3, has a probability density functicn  which deviates from Rayleigh more than does vertical polarization when the pulse widths are  short. 
 2) shows that  the transmitter power depends on the fourth power of the radar range. To double the range of  a radar. the power has to be increased 16-fold. 
 §S TRANSMIT PULSEWIDTH AND  
 T. L.: Ttie Desigti of Radially Symmetric Lenses, 1EEE Trans., vol. AP-18, pp. 
  
 BINED IN PARALLEL WITHIN A FLANGED HERMETIC PACKAGE 3OME FORM OF INTERNAL IMPEDANCE PREMATCHING CIRCUITRY IS OFTEN INCLUDED  IN ORDER TO PRESERVE TH E INTRINSIC BANDWIDTH OF  THE SEMICONDUCTOR CHIP AND TO MAKE THE TASK OF EXTERNAL IMPEDANCE MATCHING EASIER 4HE INTERNAL MATCHING ALSO INCREASES THE TERMINAL IMPEDANCES OF THE PACKAGED DEVICE  TO A LEVEL WHERE THE COMPONENT LOSSES OF THE CIRCUITRY EXTERNAL TO THE TRANSISTOR BECOME LESS CRITICAL &IGURE  IS AN EXAMPLE OF A  
 R.. E. J. 
 The capacitance is independent of the reverse-bias voltage. The series resistance is  determined by the resistivity and geometry of the metallic-like P and N regions. In the  forward-bias (conducting) state, when appreciable current is passed, the injection of holes and  electrons from the P and N regions respectively, creates an electron-hole plasma in what was  formerly the dielectric region. 
 Detection* is said to be automatic if the decision concerning the presence or absence of a received signal is made by a purely *A note on various meanings of the words detect, detector, and detection is desirable here. In radio usage, a detector has come to mean either a frequency converter (e.g., a superheterodyne first detector) or a demodulator (often the "second detector" of a superheterodyne receiver, which is usually a linear rectifier). Then, detection means the waveform modification produced by such a device. 
 Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 5.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 where datalink transmission and reception are interleaved with other modes. The prin - cipal limitation of most general-purpose datalink equipment is the low power-aperture  performance associated with omnidirectional, often shared, antenna apertures and lim - ited power levels. 
 This is referred  to as the displaced phase center antenna (DPCA) technique .7–11 In addition, some forms  of space-time adaptive processing are expressly developed to improve clutter cancella - tion with an adaptive filter, electronically displacing the antenna phase center. Electronically Displaced Phase Center Antenna.  Figure 3.11 a shows the  pulse-to-pulse phase advance of an elemental scatterer as seen by the radar receiver. 
  Ó]Ç 2ADIO WAVE MODELING IS IMPORTANT FOR A NUMBER OF REASONS  ALL OF WHICH COULD BE SUMMARIZED INTO TWO LARGE CATEGORIES OF ENGINEERING STUDIES AND OPERATIONAL PERFOR 
 At any particular range the filter notch is effectively at one frequency and the center frequency of the clutter spectrum at another. The difference between these fre- quencies results in a doppler-offset error as shown in Fig. 16.6. 
 K. Moore, R. G. 
 In atidition to being used in high-power amplifier chains, the grid-controlled tube has  also seen service in large phased-array radars that operate in the lower radar-frequency bands.  An exarnple of a grid-controlled tube that could be suitable for high-power radar applica-  tion at UHF is tlie Coaxitr~n.~~ It has wider bandwidth and better performance than conven-  tiorla1 UHF grid-control tubes because it integrates the complete RF input and output circuits  arid the electrical interactiorl system within the vacuum envelope. The RCA A15193, for  exarnple. 
 A.: Airborne Radar Motion Compensation Techniques: Optimum Array Correction Patterns, Naval Res. Lab. Rept. 
               
 Periodic pulse train. Consider a sinusoid modulated by a train of five pulses, each of width T.  The pulse-repetition period is T', and the duration of the pulse train is T, (Fig. 
 - 4O THIS POINT IN THE CHAPTER  ONLY ELECTRONIC %##- TECHNIQUES HAVE BEEN CONSIDERED  (OWEVER  RADAR OPERATIONAL PHILOSOPHY AND DEPLOYMENT TACTICS MAY ALSO HAVE A SIG 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°x A RADAR  ESPECIALLY ABOARD A SPACECRAFT "ECAUSE A RADAR BY DEFINITION MUST TRANSMIT   ITS NEAR 
 Thccoherent detector doesnotdestroyphaseinformation asdoestheenvelope detector, nordoesitdestroyamplitude information asdoesthezero-crossings detector. Sinceitutilizes 708090100--- Signalknown - - - Signalknown exceptforphase Probability otfalsealarm/ / / / / / / / / / / / / / / / / / / / I ?O30405060 2['//NorProbability offalsealarm 10999- 998 995 99 98 c95- 0-u90-OJ-OJ u a80 ~70-- .D600.D 050L CL40- 30- 20 10 5 2 () Fi2ure IO.~Comparison ofdetection prohabilities forsignalknowncompletely (coherent detector) and forsignalknownexceptforphase(envelope detector).. more information than either the envelope or the zero-crossings detector, it is not surprising  that the signal-to-noise ratio from the coherent detector is better than from the other two. 
 The values used in table 7.5may be a bit low but are satisfactory for purposes of comparisons. 7.3.2.1 The radar range equation The received power levels from the target and sea clutter, together with the thermal noise level, can be assessed using the radar range equations, the parameters in table 7.5and models for the clutter re ﬂectivity [ 6]. The power received, P r, from a target at range Rwith radar cross section (RCS) σ, is given by: πσ πλ π= μPPG RRG LL 44 41(7.1)t r222 a where μLis the microwave loss and Lais the atmospheric loss, given for a radar frequency fHz by =×−L f 1.54 10 a80 . 
 If the sequence is compared term by term with any cyclic shift of  itself, the number of agreements differs from the number of disagreements by at most one (the  correlation property). These sequences are called linear since they obey the superposition  theorem.  The peak sidelobe levels of the linear recursive sequences and of Barker codes greater  than length 5 are lower than the - 13.2 dB of the linear FM waveform. 
 Tracks and detections can be accessed in vari - ous sectored, linked-list, and other data structures so that the association process can  be performed efficiently.39 In addition to the track file, a clutter file is maintained. A  clutter number is assigned to each stationary or very slowly moving echo. All param - eters associated with a clutter point are referred to by this clutter number. 
 MTT-19, February, 1971.  69 Justesen. I> R.: Diathermy Versus the Microwaves and Other Radio-frequency Radiations: A Rose by  lrnotl1er N:unc is a Cahhage. 
 533-537, October 1965. 32. Somaini, U., and M. 
 Thewidevarietyandcomplexity ofterrainandwhatgrowsorisbuilt uponit,makesitdifficult toformulate asatisfactory theoretical modeltodescribe theback­ scatterfromland.Addingtothedifficulty aretheeffectsofweather, timeofday,andseason,as Table13.2Weibullclutterparameters 14---------------c------- -.----~---.- ..----.---------- .. Terrain/Sea state Frequency Rockymountains S Wooded hills J.. Forest X Cultivated land X Seastate1 X Seastate3 K"Beamwidth (deg) 1.5 1.7 1.4 1.4 0.5 5Pulsewidth Grazing Weioull (JIS) angle paralllctn ~--~~_._--_ .. 
 of DMS.1000 in Liberator AL.507 was started. This Liberator arrived in the UK for trials in April and May 1942, when it performed well. Meanwhile, in the UK the Air Ministry had decided that centimetric ASV should be installed in Fortresses, not Lib erators. 
 Symp. [IGARSS-92] , IEEE,  Houston, 1992, pp. 125–127. 
 Sky-wave transmission characteristics are notably variable; however, the sea echo can be used as an amplitude reference when care is exer- cised. An elementary description of sea echo behavior and some applications fol- lows. Ocean wave generation and propagation are a complex and not completely un- derstood subject; a similar statement can be made about electromagnetic scatter- ing from the waves. 
 PLANE WIDTH   Wg  IS AT LEAST  K AND  INCREASES WITH DEPTH $  `  [] WW $MAX    LL   WHERE MAX INDICATES TAKING THE LARGER OF THE TWO VALUES 4HE INCREASE IN EFFECTIVE WIDTH  CAN SOMETIMES BE REDUCED BY ADDING CAPACITIVE LOADING  WHICH CAN CONSTRAIN THE EFFEC 
 29-30,  May I. 1958. AFCRC-TR-58-145(1), ASTIA Document 152409. 
 674-675, July, 1977.  71. King, R. 
 .. 503 13,10 Sawtooth Generators. 510 INDICES ............ 
 MENTS DO NOT BEHAVE EXACTLY THE SAME  AND THE PLATFORM MOTION COMPENSATION MUST DEAL WITH MOTION NOT ONLY IN THE PLANE OF THE APERTURE BUT ALSO ORTHOGONAL TO THE APERTURE 0RE 
 R. Bamler, M. Eineder, B. 
 S. Hovanessian, “An algorithm for calculation of range in multiple PRF radar,” IEEE Transactions  on Aerospace & Electronic Systems , vol. AES-12, no. 
 Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 rainforest, provides a geographical reference that can assist with the ever-present  problem of coordinate registration77 (uncertainties in the ray path traversed by the  radar signals can lead to target positioning errors of over 100 km under some circum - stances). Second, some regions experience strong seasonal variations in vegetation  and soil moisture content, which may be reflected in measurable changes to scattering  behavior. 
 These components are not allequally harmful toMTI performance. Afre- quency modulation exactly synchronized with the PRF orany multiple thereof would cause noMTI phase error whatsoever. The phase of ground clutter ataparticular range would beshifted byagiven amount from itsvalue intheabsence ofthefrequency modulation, but theshift would beconstant forsuccessive transmitted pulses. 
 In this case, the reduction  in peak quantization lobes is said to be equivalent to adding one bit to the phase shifters in a  100-element array, 2 bits in a 1000-element array, and 3 bits in a 5000-element array.  The maximum pointing error due to quantization, is 115  1t l  l:!Oo/0 8 = 4 is (8.35)  where 08 is the beamwidth. A four-bit phase shifter, for example would give l:!00/08 = 0.049. 
 The filler selects the lower sideband f0(t) -.fir and rejects the carrier and the upper  sideband. The sidehand that is passed by the filter is modulated in the same fashion as the  transmitted signal. The sideband filter must have sufficient bandwidth to pass the modulation,  but not the carrier or other sideband. 
 This radar employs a continuous sine wave. It almost  always uses the doppler frequency shift for detecting moving targets or for measur - ing the relative velocity of a target. FM-CW radar . 
 ,- &UNDAMENTALLY  REFLECTORS ARE ANTENNAS THAT WORK ON OPTICAL PRINCIPLES  ON RECEIVE  FOCUSING ENERGY TO A FOCAL POINT AS A LENS DOES FOR LIGHT /N TRANSMIT  POWER EMANAT 
 452–466, 1958. 114. J. 
 The  radius is somewhat larger within the medium, since the spherical wavefront is flat - tened due to the slower speed of in situ propagation. ALSE.  The Apollo Lunar Sounder Experiment144,145 was a combination imager  and sounder, operating at wavelengths of 60 m, 20 m, and 2 m. 
 It is also possible to turn the CFA on and off with the RF drive-pulse, without the need for  a positive pulse applied to the cutoff electrode at the end of the drive pulse. The cutoff  electrode can be designed to operate with an appropriate constant positive-bias that allows  sufficient reentrance of the electrons when the RF drive is on but be unable to maintain the  electron stream with the RF drive orT.17 This is called RF keying, or self-keying. In principle, it  is the simplest way to modulate the CF A. 
 The effect of range on signal strength impairs the measurement of target size. Yet determi- nation of target size is needed to discriminate against radar echoes from insects, atmospheric anomalies, or birds (which in some cases have radar cross sections only slightly less than that of a jet fighter). Also, many radar receivers exhibit objectionable characteristics when signals exceed the available dynamic range. 
 7. Taylor, J. W., Jr., and J. 
 Direct current excitation forthe alternator field isprovided bya controlled rectifier fedfrom thealternator output. The controlled recti- fiermay beacombination oftransformer and rectifier controlled byasat- urable reactor, oritmay have grid-controlled thyratrons forrectification.. SEC. 
 Independent multiple beams may be generated with a single beamformer by modifying both amplitude and phase at the aperture. This can be seen from Fig. 7.3, where, for example, two indepen- dent beams are generated. 
 `¯¯¯ 
 When compared our method with these studies, in [ 5,38], authors did not do data augmentation but training data with ﬁne-tune and a new CNN model. In [ 17], authors processed data with multiple resolution and used random crop for data augmentation. The result in Table 10shows that our method can get better performance compared with other proposed method by taking a compromise between data processing and CNN training, both in accuracy and f1-score. 
 ERROR 
 In this case, the estimated Doppler parameters are the averaged results of the real ones. Although such approximation is valid for the broadside or small-squint SAR imaging, it is no longer valid for the high-squint cases because the spatially-dependent components of the DPE will seriously degrade the image quality if left uncompensated. Although there exist some methods for the spatially-variant DPE, such as the improved MAM (IMAM) method [ 24,25], their accuracy is limited as they only deal with the spatial variance of the second-order Doppler phase. 
 Biallawons, O.; Klare, J.; Saalmann, O. Technical realization of the MIMO radar MIRA-CLE Ka. In Proceedings of the 10th European Radar Conference (EuRAD), Nuremberg, Germany, 9–11 October 2013; pp. 
 37.Lind,G.:ASimpleApproximate Formula forGlintImprovement withFrequency Agility.IEEETrans.• vol.AES-R.pp.854-855. November. 1972. 
 ARRAY GEOMETRIES  WITH SIMULATOR BOUNDARIES SUPERIMPOSED A  SQUARE ARRAY WITH  SIMULATOR SUPERIMPOSED AND B  TRIANGULAR ARRAY WITH SIMULATOR SUPERIMPOSED . 
 FLOWN SURFACE  6ENERA 
 In 1942, 30 Liberator GR Mk. V were received. Of these aircraft, seven were equipped withmodel-shop versions of DMS.1000, two with SCR.517B and 20 with ASG.1. 
 SURFACE MODELS USUALLY FAIL TO EXPLAIN THE RISE IN RETURN NEAR  VERTICAL INCIDENCE  OTHER SIMPLIFIED MODELS COMBINE ,AMBERTS LAW AND OTHER ROUGH 
 MODE     4!",%  -ONOPULSE &EEDHORN 0ERFORMANCE &)'52%   0LOTS OF SUM 
 ofHealingand Ventilating En~”neers Handbook,. 422 R-FCOMPONENTS [SEC. 1111 The increase inthe coefficient isdue mainly tocreating aturbulent layer where good mixing occurs close totheactual wall, and toreducing the thickness ofthe poorly conducting layer. 
 International Association of Marine Aids to Navigation and Lighthouse Authorities, www   .iala-aism.org.  4. “Technical characteristics of maritime radio-navigation radars,” ITU-R Recommendation  M.1313, International Telecommunication Union, Geneva. 
 $#      #  !  % !    #.   05,3% #/-02%33)/. 2!$!2   n°ÎÎ 4HE CORRELATION MIXER ACTS AS A BANDPASS MULTIPLIER WITH OUTPUT  XINT X2T  4HE )&  OUTPUT OF THE CORRELATION MIXER IS EVALUATED USING THE IDENTITY   COS X COS Y   COSX   Y    COS X  
 SIGNAL RATIO %QUATION   APPLIES A SINGLE 02& WITH INTERPULSE PERIOD  4 AND ASSUMES THAT ALL PULSES IN THE  INTERVAL 4 ARE USED IN THE ESTIMATION ALGORITHM )T REDUCES EXACTLY TO %Q  FOR A  LARGE 3.2 AND FOR NARROW SPECTRA  IE   Q4  y  4HE READER IS REFERRED TO :RNIC ` FOR  FURTHER DETAILS REGARDING THE ESTIMATION OF OTHER MOMENTS OF THE DOPPLER SPECTRUM 0ULSE #OMPRESSION  0ULSE COMPRESSION HAS BEEN INFREQUENTLY USED FOR METEO 
 Refocused images of ship06 sub-image. ( a) Sub-image of ship06; ( b) Refocused image with the DCT method; ( c) Refocused image with the PGA method; ( d) Refocused image with the proposed method. The ISAR processing is not able to produce a well-focused target from airborne SAR images and the refocusing are not as good as for spaceborne SAR sub-images. 
 8.20, can be utilized to obtain a series fed array. Two of these in a  rnixer-matrix array can provide steering in two angular coordinates. One delay line at  frequency f, might be used to obtain ttie elevation steering and a second line at frequency,f2  might obtain the azimuth steering. 
 II, pp. 487–492. 84. 
   2!$!2 #2/33 3%#4)/.   £{°££ #OMPLEX /BJECTS  /BJECTS SUCH AS INSECTS  BIRDS  AIRPLANES  SHIPS  AND ANTENNAS  CAN BE MUCH MORE COMPLEX THAN THOSE JUST DISCUSSED  EITHER BECAUSE OF THE MULTIPLIC 
 Y 
 PERFORMANCE RADAR APPLICATIONS (OWEVER  IT REQUIRES A LARGE VOLTAGE WHEN HIGH POWER IS NEEDED (IGH VOLTAGE RESULTS IN GREATER SIZE AND THE NEED FOR SHIELDING FROM THE 8 
 When the transmitter is from  a communications or broadcast system, i.e., not from a radar, entries are called a  passive bistatic radar (PBR). Examples of a hitchhiker operating with a cooperative transmitter in the co-site  region are the Multistatic Measurement System  operating with TRADEX  for increas - ing ballistic missile reentry measurement accuracy40,41 and the commercial, Binet Inc.,  bistatic receiver operating with monostatic doppler weather radars to measure three- dimensional vector wind fields.2,42,43 Figure 23.3 is a block diagram of the Binet Inc.- developed prototype. Examples of hitchhikers operating with a cooperative transmitter in the receiver- centered region are the  Covin Rest  program, operating with the space-shuttle radar for  synthetic aperture radar (SAR) ground mapping44; the TBIRD  program operating with  Joint STARS for silent air-to-ground attack via forward-looking bistatic SAR2,45; and  the BAC  program operating with AWACS  for alerting and cueing short range, mobile  air-defense systems.46,47 FIGURE 23.3  Simplified block diagram of the Binet Inc.-developed bistatic wind measurement prototype  system. 
 OF 
 Therefore, the incident power is absorbed in the ferrite so that  the average power capability can be a problem. Air or water cooling might be needed.  The ferrite material may be biased, as for example a latching-ferrite circulator, to permit  the handling of higher power.4s Since the latching-ferrite receiver protector is undamaged by  high power when in either state, protection from nearby transmitters can be had by inserting a  passive TR-limiter following the ferrite. 
   2!$!2 #2/33 3%#4)/.   £{°£x &)'52%   -EASURED 2#3 OF A LARGE NAVAL AUXILIARY SHIP FOR HORIZONTAL INCIDENT POLARIZATION 4HE  UPPER PATTERN A  IS FOR  '(Z  AND THE LOWER PATTERN B  IS FOR  '(Z 3HOWN ARE THE     AND   PERCENTILE LEVELS BASED ON THE STATISTICS OF THE DATA OVER n ASPECT ANGLE WINDOWS . £{°£È  2!$!2 (!.$"//+  £{°ÎÊ , -Ê*, 
 FIG. 8.14 Ratio detector. (From Ref. 
        &)'52%   2ADAR IMAGES USING  '(Z PULSE DURATION ALONG AN  
 NOISE RATIO LOSS IN M OVING TARGET INDICATOR v  0ROC )%%%   VOL   PP n  &EBRUARY   7 7 3HRADER AND 6 'REGERS 
 103, pp. 8113–8127, 1998. 83. 
 ATMOSPHERE SYSTEM  DIFFRACTION OCCURS WHERE THE STRAIGHT 
 Allhougll the above assutned a rand'ln distributiori of phase error across the aperture for  coriiputation of the rms sidelobe level, the actual phase distribution with quantized phase  stlifters is likely to he periodic. The periodic nature of the quaritized phase will give rise to  TilEFLHTRUNICALI.Y STEERED PIIASI:I) ARRAY ANTENNA INRADAR321 (rougher surface) willgivelowersidelobesthananantenna withalargercorrelation inter­ val.Anerrorstretchingmostofthe lengthoftheantenna islikelytohaveaworseeffectthan alocalized bumpordentofmuchgreateramplItude. Therefore smalldisturbances suchas screwsandrivetsonthesurface oftherellector willhavelittleeffectontheantenna radiation pattern. 
 For these reasons, Butler beam-forming  networks with large numbers of elements are not the general rule.  It is possible to construct planar arrays with Butler networks. A 2P by 2q element array (p,  q are integers) requires 2P + 29 networks to achieve 2P+q beams. 
 C. Srivastava (eds.), Radar and Atmospheric Science: A Collection of  Essay in Honor of David Atlas , Meteorological Monographs, V ol. 30, Boston: AMS, 2003. 
 LFM  has been successfully employed operationally (e.g., in the U. S. Navy AN/APS-116  and AN/APS-137) since the 1970s. 
 At low angles where the ranges are Jong, a low prl is used. At the higher angles  where the ranges are short, a high prf can be used. If an increase in complexity can be tolerated,  a number of multiple elevation beams can be scanned simultaneously to increase the data rate,  unambiguous range, and/or number of pulses per beam position. 
 Each of tlie  boxes labeled S represents a SPST switch. The N ports ofeach one-by-N switch are connected  to N lines of different lengths I ,, I*, . , I,,,. 
 HF OVER-THE-HORIZON RADAR  20.836x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 144. J. L. 
 REFLECTOR TARGET GLINT ERROR FOLLOWING APPROXIMATELY THE EQUATION   EH      RR F RRFCOS COS    WHERE E    ERROR  SAME UNITS AS H  MEASURED AT THE TARGET RANGE RELATIVE TO THE TARGET  Q   MAGNITUDE OF SURFACE REFLECTION COEFFICIENT  H   HEIGHT OF TARGET  E    RELATIVE PHASE DETERMINED BY GEOMETRY OF DIRECT AND SURFACE 
 GERING )F   NNF FR VR V r    PL SL S    FROM %QS  AND   IS SUBSTITUTED INTO %Q     )FFR V 
 andfairweather cumulus cloudwithamoderadiusof4jim,a watercontentof0.063g/mJ,andadropdensityoflOO/cm3.~9.9o. applies for the region around 183 Gtlz. Tlie relative minimum at 94 GHz with an attenuation  of 0.3 dB/km is a likely frequency for millimeter radar applications. 
 W. Schunk, “Parameterized ionospheric model: A global ionospheric parameterization  based on first principle models,” Radio Science , vol. 30, pp. 
 The imaging radar reference5  cited earlier provides an excellent review of many of these applications. 18.3 ALTIMETERS In its most general form, an altimeter is a radar device designed to measure the verti - cal distance between the radar and the surface below. In airborne applications, the  resulting “altitude” is a measure of the clearance beneath the aircraft. 
 Note that the improvement factor of a two-pulse  canceler is almost as good as that of the 8-pulse doppler-filter bank. The three-pulse canceler is  ever1 better. (As mentioned previously, maximizing the average improvement factor might not  be tlie only criterion used in judging the effectiveness of MTI doppler processors.)  If a two- or three-pulse canceler is cascaded with a doppler-filter bank, better clutter  rejection is provided. 
 In practice the repeater is limited in gain by the usual transmit/receive isolation (ring-around problem); so additional complex- ity must be added. At the same time, use of more complex pulse compression waveforms could be more easily accommodated by not requiring the sophisti- cated processing hardware to be missile-borne. TVM is essentially a variation of semiactive homing. 
 Figure 6.22 and  Eq. 6.50 define how the filter with impulse response h(n), followed with decimation  by factor D, is implemented in a polyphase structure. The input signal x(n) is divided  into D parallel paths by the “commutator,” which outputs samples in turn, rotating in a  counterclockwise direction, to each of the FIR filters operating at the reduced sample  rate. 
 If we are picking  up echoes from more than one aircraft, then we shall see  a number of small echo blips along the line. Some may  be moving away, some home.  Although this is ‘basic’ radar, it is, indeed, just the  sort of elementary display which was possible when  Mr A. 
 Airborne Search set. Figure 11.27 shows anexternal view ofther-fhead used ona3-cm search and navigation setofrecent design. Abroad flatcontainer was dictated bythe space available incertain aircraft. 
 Electron., vol. 17, pp. 71-83, May 1985. 
 RANGE POINTS  7ITH THIS ASSUMPTION   FV FVD DMAX MAX MIN MINSIN SIN    LQ LQ  4HUS  THE TOTAL WIDTH OF THE DOPPLER SPECTRUM IS  $FV D 
 W.:Computer Control ofaMultifunction Radar,RCAEllgilleer, vol.18,no.I,June­ .Iuly.1972. 121.Baugh.R.A.:"Computer Control ofModern Radars," Privately published byRCAInc.,1973. 122.Motkin. 
 With apassive and linear load, the long-time average ofboth the current through the secondary ofthesynchro and thevoltage across itmust bezero (Wave- form 1?,Fig. 13.45). Thus theabsolute current orvoltage atthebegin- ning ofthe modulated sawtooth will not beconstant, but will change with the modulation amplitude and will reverse sign when the sawtooth does. 
 The subtracter outputs are called difference signals, which are zero when the target is on axis, increasing in amplitude with increasing displacement of the tar- get from the antenna axis. The difference signals also change 180° in phase from one side of center to the other. The sum of all four horn outputs provides a ref- erence signal to allow angle-tracking sensitivity (volts per degree error) even though the target echo signal varies over a large dynamic range. 
 (When pulse compression is used, the pul1:,e . RADAR CLUTIER 473  width r in Eq. ( I 18} is that of the comprcssccf pulsc.f If the statistics of the clutter echoes arc  similar to the statistics of receiver noise, then the signal-to-clutter ratio in Eq. 
 Turin, G. L.: An Introduction to Matched Filters, pp. 311-329. 
 MONOSTATIC   PSEUDO 
 TIZATION LOBES CAN BE REDUCED BY DECORRELATING THE PHASE 
 There is, in fact, no greater similarity  between the early echo systems of radar (which pro-  tected the shores of the British Isles at the beginning of  the Second World War) and the latest radar navigational  was than there is between a carborundum-crystal  ears and a modern television receiver. They have | 15 ten  . radio communication as a common link, and that is  about all. 
 W. Ryde and D. Ryde45) ch19.indd   9 12/20/07   5:37:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The ﬁrst operational system was developed in the UK for the RAF at the start of WWII. Since then there has been a continuousevolution of technology and capability, which still continues today in many countries. This book describes the evolution of airborne maritime surveillance radars from a British perspective. 
 From Figure 9, it can be found that the proposed KA-DBS algorithm can focus the scene much clear than the other algorithms, and the texture information can be easily distinguished. For example, the roads in Figure 9d are much thinner than that in Figure 9a–c. This can be explained that the forward and backward predicted pulses in each CPI are well utilized to improve the cross-range resolution in KA-DBS imaging. 
 AZIMUTH SECTORS AND INCREASING DETECTION THRESHOLDS IN EACH SECTOR IF TOO MANY  DETECTIONS OCCUR  02&S HIGH ENOUGH SO THAT ALL TARGETS WITH RADIAL VELOCITIES BELOW  KNOTS CAN BE  CENSORED  3ENSITIVITY VELOCITY CONTROL 36#   WHICH CENSORS RADIALLY SLOW  SMALL TARGETS   WHILE ACCEPTING RADIALLY FAST TARGETS AND LARGE TARGETS #OMBINATIONS OF TECHNIQUES  THROUGH  ARE USED IN MOST AIR 
     PP n  *ULY   7 7ASYLKIWSKYJ AND 7 + +AHN  h%LEMENT PATTERNS AND ACTIVE REFLECTION COEFFICIENT IN UNIFORM  PHASED ARRAYS v )%%% 4RANS  VOL !0 
 16+3 theoscillator and amplifier shown inFig. 16.11 and tosend thei-fsignal, together with thereference signal, directly through thedelay line. The amplifier then works attheintermediate frequency used inthereceiver. 
 Bracewell, J. H. Deuter, and J. 
 Firm correlation  DF signal goes with radar track having largest Pj (i.e., Pmax)  when Pmax ≥ TH and Pmax ≥ Pnext + R. 2. Tentative correlation  DF signal probably goes with radar track having largest Pj  (i.e., Pmax) when TH > Pmax ≥ TM and Pmax ≥ Pnext + R. 
 H.  Taylor, L,. C. 
 .I.. vol. 27. 
 Equations (30) and (33), combined, give only the average level S ofground return. Particular signals vary widely. Onthe PPI, with a medium gain setting, ground return can beseen toconsist ofmany bright signals. 
 F. Cavaleri, “High resolution radar sea scatter, experimental observations and  discriminants,” Naval Research Laboratory Report No. 8557, 1982. 
 (1.3), it can appear as the cube, as the square, or as the first power in specific situations, some of which are described later in this section and in other chapters. In addition to its use for range prediction, the radar equation forms a good basis for preliminary system design by providing a guide to the possible tradeoffs among the various parameters that enter into radar performance. The minimum detectable signal 5min, which appears in the radar equation, is a statistical quantity and must be described in terms of the probability of detection and the probability of a false alarm. 
 SCATTER 2#3 ROLLOFF USUALLY REQUIRES SIMULATION 4HE FORWARD 
 ING IN PROGRESSIVELY TO SHOW A SECTION OF THE SPECTRUM WHERE A  K(Z CLEAR CHANNEL IS EVIDENT  CENTERED  ON  -(Z 4HE DATA WAS RECORDED AT LATITUDE  3  LONGITUDE  % . Óä°{Ó  2!$!2 (!.$"//+  !LMOST WITHOUT EXCEPTION  (& RADARS HAVE OPERATED ON THIS PRINCIPLE OF NONINTER 
 The image intensity for individual pixels with a single-look SAR  follows the Rayleigh distribution (actually the exponential distribution if square-law  detection is used). Most SAR processors sacrifice some spatial resolution by aver - aging, say, four pixels together after detection. Transmitting more bandwidth than  needed for range resolution accomplishes this purpose without loss of needed spa - tial resolution,180 but it takes more transmitter power. 
 The antenna ofthis set./’ .= \In , \isplaced very close tothe ground %’ I \ \ ,= , \\insuch away that the beam is .sg ,’\\ tilted upinelevation and lo\v-angle /’\ coverage deliberately sacrificed. A\\lobe pattern such asthat shown 0123456 Elevation angle,ndegreesinFig. 6.20 isthus produced. 
 The most useful form of the mixer chart1 is shown in Fig. 3.2. The heavy line shows the variation of normalized output frequency (H - L)IH with normalized input frequency LIH. 
 For these reasons, low sidelobes are desirable on both  receive and transmit (see Schrank,32 Patton,33 and Chapter 2 in Farina34). Sometimes  the increase in main-beam width that results from low sidelobes worsens the problem  of main-beam jamming; this consequence should be carefully considered in specifying  the antenna radiation pattern. Usually, specification of the sidelobes as a single number (e.g., −30 dB) means  that the peak of the highest sidelobe is 30 dB below the peak of the main beam. 
 Such “smooth” surfaces can be, for example, the sides of trucks of the  extended hulls of ships. Radar System Engineering  Chapter 3 – The Radar Equation  16     3.3 The Radar Horizon   The range of coverage of Radar equipment can be limited due to minimum received power PRmin  and as well due to the visibility (i.e. the Radar horizon). 
 ABLE DOPPLER SPACE&)'52%  !VERAGE 3#2 IMPROVEMENT FOR THE  D" #HEBYSHEV FILTER BANK SHOWN  IN &IGURE  #0)    PULSES /PTIMUM IS FROM &IGURE  .   -4) 2!$!2  Ó°xÇ 4HE MISMATCH LOSS OF THIS FILTER IS  ,M    D"  WHICH IS WELL BELOW THAT OF A  D"  $OLPH 
 Figure 7.34 illus - trates the tracking of a single target using multiple hypothesis techniques. In this  example, many hypotheses are formed and, over successive measurement intervals,  successfully pruned away leaving only one correct track. The region of applicability for the more sophisticated algorithms is determined by two  parameters: the density of extraneous detections l (detections per unit area or volume)   FIGURE 7.33  A comparison of the execution time for  the Munkres (optimum), JVC (optimum), and Auction  (suboptimum) algorithms shows the rapid increase in  computation required for Munkres as the number of  rows in the assignment matrix increases. 
 W. L. Wolfe and G. 
 Mixer --c LO Power  oscillator 1  T R  Figure 4.33 Block diagram of a noncoherent MTI radar. _,  138INTRODUCTION TORADAR SYSTEMS gaussian-shaped beamand118pulsesbetween thehalf-power beamwidth oftheone-way antenna pattern. Theparameter CIListheratioofthermsclutterpowertothereceiver-IF limitlevel. 
 The maximum efficiency of the single-tuned filter occurs for Br w 0.4. The correspond-  ing loss in signal-to-noise ratio is 0.88 dB as compared with a matched filter. Table 10.1 lists  Table 10.1 Efficiency of nonmatched filters compared with the matched filter  input signal  Rectangular pulse  Rectangular pulse  Gaussian pulse  Gaussian pulse  Rectangular pulse  Rectangular pulse  Rectangular pulse Loss in SNR compared  with matched filter, dB  0.85  0.49  0.49  0 (matched)  0.88  0.56  0.5  I Filter  Rectangular  Gaussian  Rectangular  Gaussian  One-stage,  single-tuned circuit  2 cascaded single-tuned  stages , .. 
 SERIES FED ARRAY ANTENNAS v IN  0HASED  !RRAY !NTENNAS  ! ! /LINERAND AND ' ( +NITTEL EDS   .ORWOOD  -! !RTECH (OUSE     PP n  ! 2 ,OPEZ  h-ONOPULSE NETWORKS FOR SERIES FEEDING AN ARRAY ANTENNA v IN  )%%% )NT 3YMP  !NTENNAS 0ROPAG $IG    , 3TARK  2 7 "URNS  AND 7 0 #LARK  #HAPTER  IN  2ADAR (ANDBOOK  - ) 3KOLNIK ED   ST %D   .EW 9ORK -C'RAW 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar.  HF OVER-THE-HORIZON RADAR  20.776x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 11. 
 SIGNAL  % FIELDS BECAUSE THE SUM HORN OCCUPIES SPACE  DESIRED FOR THE DIFFERENCE SIGNALS  'ENERALLY  AN UNDERSIZED SU M 
 SPHERE IS NEARLY AN EXPONENTIAL FUNCTION OF HEIGHT 4HE DECREASE OF  . WITH HEIGHT CLOSE  TO THE %ARTHS SURFACE WITHIN  KILOMETER  IS SUFFICIENTLY SMOOTH  HOWEVER  TO ALLOW AN APPROXIMATION OF THE EXPONENTIAL FUNCTION BY A LINEAR FUNCTION 4HIS LINEAR FUNC 
 40. J. E. 
 J. Sofko, “The CCRS ground-based microwave facility,”  IGARSS88 , vol. 1, pp. 
 In the receiver following the main-beam clutter filter, the clutter-spreading re- quirements are not germane. The SNR and false-target considerations then be- come the limiting factors at high-sideband frequencies as well as low-sideband frequencies. Narrowband Noise. 
 702–703, May 1976. 11. G. 
 ICE SURFACES HAVE SLOPES LESS THAN  ^n  WHICH  ALTHOUGH SMALL  IS SUFFICIENT TO TRICK A CON 
 LOOP LOW 
 Brennan, L. E., and l. S. 
 SQUARED DISTRIBUTION SURVIVAL FUNCTION +M 
 AES-25, July 1989. 89. Lord, D. 
 IEEE Microw. Mag. 2002 ,3, 48–56. 
 pp.199-208. January. 1978. 
 Lien, E. L.: Advances in Klystron Amplifiers, Microwave J., vol. 16, pp. 
 Such radars might be employed  for ECCM, improving tlie detection of targets with fluctuating cross section and reducing the  effects of glint (Sec. 5.5). With a high tuning rate, the pulse-to-pulse frequency can be made to  appear pseudorandom, especially if the pulse repetition frequency or the tuning rate is varied  rapidly. 
 There are a large number of broadcast stations that  have 500-kW transmitters and antennas with more than 20-dB gain. Measurements  made on the middle Atlantic coast of the United States show HF broadcast-band sig - nals with strengths of 5 to 10 mV/m. These ambient levels must be accommodated  in receiver design because a wideband front end is desirable for rapid and frequent  frequency changes. 
           
 It has also been called the quantization error, a more descriptive name. The average  number of cycles N of the beat frequency& in one period of the modulation cyclc 1, is rb /fm,  where the bar over6 denotes time average. Equation (3.1 1) may be written as  86INTRODUCTION TORADAR SYSTEMS greatertherange,thegreatertheechoareailluminated hytheheam.Forextended targets, therefore, thelow-frequency amplifier gainshouldincrease 6dB/octave. 
 MAP 3!2  THE BEAM REMAINS NORMAL TO THE FLIGHT PATH THE LATTER IS ASSUMED TO BE A STRAIGHT LINE AT CONSTANT ALTITUDE  AND CONTINUOUSLY OBSERVES A  SWATH OR  STRIP  OF TERRAIN  PARALLEL TO THE FLIGHT PATH EXTENDING FROM SOME MINIMUM RANGE  2 MIN TO SOME MAXIMUM  RANGE 2MAX FROM THE FLIGHT PATH. £Ç°{  2!$!2 (!.$"//+  &OR STRIPMAP 3!2  THE SYNTHETIC APERTURE ANGLE  $P  IS ESSENTIALLY EQUAL TO THE REAL 
 Historically, these waveforms were selected ahead of  time and built into the radar hardware and software. Most modern airborne radars  solve this geometry in real time and continuously select the best available frequency,  PRF, pulsewidth, transmit power, scan pattern, etc. Unfortunately, the specifics of the waveform are unpredictable even to the radar  without exact knowledge of the aircraft-target-earth velocity-geometry set and mode  of operation requested by the operator or mission software. 
 3.10 over those angles that map  into a given doppler filter’s passband. The noise normalization term, k, must also be  modified to reflect the cascaded noise gain of the MTI and doppler filter bank as N k W W W k N Wg i iN i i iN ( ) cos( ) = − + =+ =− ∑ ∑6 8 2 22 11 11 π/i i i iN W k N k N+ =− ∑ = −2 12 4 0 1 cos( ); , π/   (3.12) for three-pulse MTI and cascaded N-pulse doppler filter bank, where Wi are the dop - pler filter weights, or  N k W W W k N kg i iN i i iN ( ) cos( ); = − = =+ =− ∑ ∑2 2 02 11 11 π/ , ,N−1  (3.13) for two-pulse MTI and cascaded N-pulse doppler filter bank. 3.6 SCANNING-MOTION COMPENSATION Figure 3.14 a shows a typical antenna main-beam radiation pattern and the response of  a point scatterer for two successive pulses when the antenna is scanning. 
 E. M., arid E. L. 
 Both kinds of detectors test whether the test cell has a return sufficiently larger  than the reference cells. Clutter maps allow variation in space, but the clutter must be  stationary over several (typically 5 to 10) scans. Clutter maps store an average back - ground level for each range-azimuth cell. 
 ON REGION IS PROBABLY THE  ENGINE INTAKES BECAUSE THEY ARE THRUST WELL FORWARD OF THE WING LEADING EDGES 4HE INTAKES OF THE & 
   PP n    4 4 4AYLOR  h$ESIGN OF CIRCULAR APERTURES FOR NARROW BEAMWIDTH AND LOW SIDELOBES v  )%%% 4RANS   VOL !0 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°{£ AND THE DIMENSIONLESS TRACK FILTERING PARAMETER  FTRACK &IGURE  BOUNDS THIS REGION  OF APPLICABILITY 7HEN  K AND FTRACK ARE SMALL  THEN THERE IS NO NEED FOR ANY MORE THAN  SIMPLE NEAREST NEIGHBOR TRACKING  AND INDEED  MOST TRACKING SYSTEMS STILL USE THIS  APPROACH !S  K INCREASES  THERE IS GREATER RISK OF FALSE ASSOCIATION DECISIONS HOWEVER   THE EFFECT OF THIS IS REDUCED IF  FTRACK IS SMALL !T THE OTHER EXTREME  WHEN  K AND FTRACK ARE  LARGE  THE TRACKING PROBLEM IS ESSENTIALLY UNSOLVABLE WITHOUT BASIC CHANGES TO THE RADAR DESIGN PARAMETERS TO REDUCE THEM 4HERE IS AN INTERMEDIATE REGION WHERE SOPHISTICATED ASSOCIATION HAS VALUE 4HE WIDTH OF THIS REGION IS VERY SPECIFI C TO THE PARTICULAR PROB 
 Ê   , 
 The modulation and demodulation to obtain range are the same as  used in frequency-modulated continuous-wave (FM-CW) radar,56 but the transmission  remains pulsed. Suppose the dwell time is divided into two looks. In the first look, no FM is applied,  and the doppler shift of the target is measured. 
 The 1960s saw the availability of the crossed-field amplifier, a  tube related to the magnetron, There are several variations of crossed-field amplifiers, each  with its special properties; but they are all characterized by wide bandwidth, modest gain, and  a compactness more like that of the magnetron than the klystron or the traveling-wave tube.  Solid-state devices such as the transistor and the bulk--cffect and avalanche diodes can  also be employed as radar transmitters. They have some interesting properties as compared to  the microwave vacuum tube, but the individual devices are inherently of low power. 
 Satellite-borne radarshavealsobeenusedforremotesensingasmentioned below. RemoteSellsillg. Allradarsareremotesensors; however, asthistermisuseditimpliesthe sensingofgeophysical objects,orthe"environment." Forsometime,radarhasbeenused asaremotesensoroftheweather. 
 However, subsequent advances in digital  technology, originally developed ror applications other than radar, have allowed the practical  implementation of the multiple delay-line cancelers and multiple pulse-repetition-frequency  MTI radars indicated by the basic MTI theory.  Automatic detection and tracking, or ADT (Secs. 5)0 and 10.7), is another important  development whose basic theory was known for some time, but whose practical realization  ,iad to await advances in digital technology. 
 Yan, H.; Wang, R.; Li, F.; Deng, Y.; Liu, Y. Ground moving target extraction in a multichannel wide-area surveillance SAR /GMTI system via the relaxed PCP . IEEE Geosci. 
 Oseen, C.W. Ber die Stoke’sche Formel und Über Eine V erwandte Aufgabe in der Hydrodynamik ; Almqvist & Wiksell: Stockholm, Sweden, 1911. 19. 
 Schleher, Introduction to Electronic Warfare , Norwood, MA: Artech House, Inc., 1986.  4. D. 
 Atangles near 4°the variation isfast, but theillumination oftheplane bythelower beam may besoweak that no echo isobtained, and therefore noheight can beinferred. Ifboth the antennas arenearer the ground, the effective angle isincreased, but the beams areboth tipped upsomuch that coverage onaircraft atlow and medium altitude issacrificed. Even inthecase wehave considered, an aircraft 10,000 fthigh and 50miles away, orone 5000 fthigh atarange of25miles, would fallintheunmeasurable class. 
 A second approach is through the use of shorter wavelengths. Shorter wavelengths result in improved signal-to-clutter ra- tios owing to the fact that the backscattered weather signal power is inversely proportional to X4 while the ground clutter return is only weakly dependent on wavelength. If one assumes that the clutter signal is wavelength-independent and the antenna beamwidth is fixed, Eq. 
 Solid-state devicessuchasthetransistor andthebulk-effect andavalanche diodescan alsobeemployed asradartransmitters. Theyhavesomeinteresting properties ascompared to themicrowave vacuumtube,buttheindividual devicesareinherently oflowpower. Thereisnooneuniversal transmitter bestsuitedforallradarapplications. 
 PROCESSING ALGORITHMS  DEPEND 
 --  4O COMPUTE THE VARIOUS WEATHER PRODUCTS NECESSARY FOR FORECASTING  WARNING  AND OTHER OPERATIONAL ACTIVITIES  THE FIRST THREE SPECTRUM MOMENTS CORRESPONDING TO RECEIVED POWER  MEAN RADIAL VELOCITY  AND DOPPLER SPECTRUM OR VELOCITY WIDTH MUST BE ESTIMATED +EELER AND 0ASSARELLI  REVIEW STANDARD ESTIMATION TECHNIQUES AND ERRORS FOR SPECTRUM  MOMENT ESTIMATION &OR THE HIGHEST RESOLUTION MEASUREMENTS  THESE SPECTRAL MOMENTS MUST BE COMPUTED AT EACH RANGE GATE SENSED BY THE RADAR AND CONVERTED INTO MEANINGFUL METEOROLOGICAL INFORMATION 4HE NATURE OF THE DISTRIBUTED METEOROLOGICAL TARGET  WHICH SHALL BE DISCUSSED NEXT  IMPOSES SOME SPECIAL REQUIREMENTS NOT GENERALLY CONSIDERED FOR HARD  NONFLUCTUATING TARGETS ON THE PROCESSING TECHNIQUES TO ESTIMATE THESE MOMENTS )T CAN BE SHOWN THAT THE RECEIVED SIGNAL FROM METEOROLOGICAL TARGETS IS WELL REPRE 
 I>avis. J. K. 
  Ê-,Ê**  /" - )N THIS SECTION  WE BRIEFLY DISCUSS SEVERAL SPECIFIC ASPECTS OF 3!2  SPECIFICALLY POLARI 
  SYNTHETIC APERTURE RADAR DESIGN v  #ANADIAN  *  2EMOTE  3ENSING   VOL     PP n    0 ! &OX  ! 0 ,USCOMBE  AND ! ! 4HOMPSON  h2!$!23!4 
   &" &)'52%  34!0 BLOCK DIAGRAM ELEMENT SPACE PRE 
 NITION .#42  RADAR  AS COMPARED TO A COOPERATIVE RECOGNITION SYSTEM SUCH AS )&& IDENTIFICATION FRIEND OR FOE   WHICH IS NOT A RADAR 7HEN TARGET RECOGNITION INVOLVES SOME PART OF THE NATURAL ENVIRONMENT  THE RADAR IS USUALLY KNOWN AS A  REMOTE SENS 
 CONTROLLED TUBES USED FOR EARLY RADARS !S TIME PASSED  THE DEMANDS FOR IMPROVED RADAR PERFORMANCE OUTRAN THE CAPABILITIES AVAILABLE FROM THE MAGNETRON &ORTUNATELY  OTHER TUBE TYPES WERE INVENTED THAT OVER 
 With apower output greater than 50kwand a pulse width of7to15psec, thesetisvery conservatively designed, and can track targets much beyond itsrated range. Angular accuracies attainable inpractice with this equipment, about +1°,aretoo poor to permit good blind antiaircraft tfire, and because ofground reflections the equipment suffers from severe errors inreading elevation atangles smaller than about 10°. However, this versatile, rugged, and readily mobile equipment was available inquantity early inthe war, and served many useful roles, being used forfirecontrol, short-range search and warning, and searchlight control. 
 The Taylor aperture illumination has also been applied to synthesizing the patterns of  circular, two-dimensional antennas.86·87 It has been widely used as a guide for selecting  antenna aperture illuminations.  When the difference pattern of a monopulse antenna can be selected independently oft he  sum pattern, as in a phased array, the criterion for a good difference pattern is to obtain  maximum angle sensitivity commensurate with a given sidelobe level. Bayliss811 txis described  a method for obtaining suitable monopulse difference patterns on this basis. 
 Brown. R. M .. 
 Even more important, it  allows the student to research the literature and to be a bit more creative than is possible by  simply solving standard problems.  A book of this type which covers a wide variety of topics cannot be written in isolation. It  would not have been possible,without'the many contributions on radar that have appeared in  the open literature and which have been used here as the basic source -material. 
 It is encouraging, however, when theoreti-  cal considerations substantiate the qualitative, intuitive reasoning upon which most practic~l  engineering decisions must usually be based, for lack of any better criterion.  C  Single frequency-modulated puke. Ambiguitie5 may be avoided with a single-pulse waveform  rather than a periodic-pulse waveform. 
 Multi-sensor ISAR radar imaging and phase adjustment based on a combination of signal sparsity and total variation is considered in [ 25]. To improve the azimuth resolution of ISAR images a fractional sparse energy representation method combined with fractional Fourier transform is proposed in [ 26]. The clock jitter inﬂuence on the signal to noise ratio (SNR) of an analog-to-digital-converter of the ISAR signal acquired from the space object is analyzed in [ 27]. 
 21 23. 1975, pp. 527-532. 
 The  transmitter and receiver can be, and usually are, located at those sites to minimize  transmission line losses. In nearly all cases of bistatic operation, antenna separation  is selected to achieve some operational, technical, or cost benefit, and is usually a  significant fraction of the target range.1 Bistatic radars have been designed, devel - oped, tested, and in some cases, deployed for military, commercial, and scientific  applications. Typical military applications include air and space surveillance and range  instrumentation. 
  
 #7 WAVEFORMS HAS BEEN WIDELY ADOPTED  DRIVEN MAINLY BY CONSTRAINTS ON SPEC 
 A bistatic radar cross section ab is defined to apply for this situation. The symbol a in the preceding equations implies a monostatic cross section. Range equations for bistatic radar are obtained from the foregoing monostatic equations by replacing the range R and the target cross section a by the corresponding bistatic quantities. 
 -   ! 6 /PPENHEIM AND 2 7 3CHAFER   $IGITAL 3IGNAL 0ROCESSING   ND %D  %NGLEWOOD #LIFFS  .*  0RENTICE 
 ESES v 0HILOS 4RANS 2 3OC ,ONDON  VOL   SER !  P      , 6 "LAKE  h4HE EFFECTIVE NUMBER OF PULSES PER BEAMWIDTH FOR A SCANNING RADAR v  0ROC )2%    VOL   PP n  *UNE    ' 6 4RUNK  h#OMPARISON OF THE COLLAPSING LOSSES IN LINEAR AND SQUARE 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar.  SYNTHETIC APERTURE RADAR  17.336x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 Horizontal antenna separation :  δλ ψ π ψ γhR nL= +cos sin( ) 2SN R (17.62) Furthermore, when the phase moves through an interval of 2 p, an ambiguity occurs  in terrain altitude measurement. 
 SCAN PROBABILITY OF DETECTION. 
 POLARIZED STICK ANTENNAS  M LONG   FOUR OF WHICH WERE AIMED AT  o n  ( POLARIZED  AND  on 6POLARIZED  FROM THE SURFACE TRACK  AND THE TWO MIDBEAM  ANTENNA PATTERNS WERE ALIGNED AT  n AND n EACH ( AND 6 POLARIZED  4HE THIRD BEAM  ON EACH SIDE HELPED TO REMOVE THE FOURFOLD DIRECTIONAL AMBIGUITIES THAT PLAGUED 3!33 WIND RETRIEVALS 4WO  
 BASED 3/,!3 AND NON 
 3.10b. The modulation need not necessarily be triangular; it can be  sawtooth, sinusoidal·, or some other shape. The resulting beat frequency as a function of time is  shown in Fig. 
 LINEAR EFFECTS Óä°ÈÊ / 
 Another advantage isthat adeflection oftheplanarmirrorbyanangle0resultsinthebeamscanning through anangle 20. Asimilarprinciple isusedintheconfiguration showninFig.7.14toobtaina360° rOlating-beam antenna without theneedforRFrotaryjoints.Inthiscutaway sketch,four polarization sensitive parabolic reflectors surround arotating twist-reflector mirror.For convenience, tb.eentirestructure isshownenclosed withinaradome. Fixedfeedsilluminate eachreflector. 
 STATE TRANSMITTER MODULES CAN ACHIEVE UP TO  BANDWIDTH OR MORE WITH ACCEPTABLE EFFICIENCY&)'52%  "Y COMBINING THE OUTPUTS OF THOUSANDS OF TRANSISTOR AMPLIFIERS   THE CUMULATIVE AVERAGE POWER OUTPUT OF SOLID 
 For all practical purposes the feed is out of the path of the reflected energy, so that  there is no pattern deterioration due to aperture blocl~ing nor is there any significant amount  of energy intercepted by the feed to produce an impedance mismatch.  It should be noted that the antenna aperture of an offset parabola (or any parabolic  reflector) is the area projected on a plane perpendicular to its axis and is not the surface area.  The offset parabola eliminates two of the major limitations of rear or front feeds. 
 The output waveforms can beused directly forswitching purposes, or they can serve asameans ofgenerating pulses ofhalf thefrequency of theoriginal ones. Inalltheabove circuits itisfeasible touseEPP self-biasing, but care must betaken that the bias voltage isindependent ofduty ratio. This canbeassured byusing acommon self- Rc bias resistor forboth tubes, provided their loads arethesame.--- --- Cathode-coupled Multivibrator.—F igure V& 13.16 illustrates adifferent type ofsingle- Irk stroke multivibrator which isconsiderably = . 
 This sampled phase noise spectrum provides a method for  comparing different LO phase noise profiles and their relative impact on the overall  performance of the system.  ˆ( ) ( ) | ( ) | L f L f kf H f kf k= ′+ +  =−∞∞ ∑ PRF PRF2 (6.13) Sinusoidal Modulations.  Radar performance is affected by both random and sinu - soidal modulations. 
 96. Eastwood. L: "Radar Ornithology," Methuen & Co., Ltd., London. 
 Nearest the magnetron isthe AFC attenuator and mixer. The mixer isofthetype shown inFig. 11.25, Sec. 
 10.4. The related subject oflong-line effect isdiscussed inSec. 11”1.1 Because the interaction between the pulser and the magnetron has only recently been understood, many serious difficulties have been alleviated inthepast bytheunsatisfactory process ofcut-and-try. 
 22-24, 1980. 46. Forrest, J. 
  LQQSIN SIN  MAX MIN  &OR SHORT PULSES AND ANGLES AWAY FROM VERTICAL  THIS IS  $$FV Dy LQQCOS  )N TERMS OF PULSE LENGTH  IT BECOMES  $FVC HD T LQ QCOS SIN    )F THE ANGULAR DIFFERENCE ACROSS THE ILLUMINATED RECTANGLE IS SMALL ENOUGH SO THAT  R   IS ESSENTIALLY CONSTANT  THE DOPPLER SPECTRUM IS A RECTANGLE FROM FMIN TO FMAX&)'52%     'EOMETRY OF DOPPLER 
 The time of fall was set manually into the bombsight, as were correctionsfor ballistics and stick length. The blind bombsight calculated the range from the target at which to release the bombs. The line of attack was controlled by the pilot ﬂying the aircraft while observing the bearing of the target as revealed by the pilot ’s azimuth indicator. 
 Pair 8. Similarly to the amplitude variations of pair 1, sinusoidal phase vari- ation over the passband creates symmetrical paired echoes in the time domain in addition to the main signal g(t). The echoes are replicas of the main signal, de-r00g(t)=JG(f)exp(j27rft)df— 00 PAIRED ECHOES: HIGH SIDELOBES H3.2db): o t^.\ o sin TrBt2. 
 An average radar installation has a life normally exceed - ing 10 years, so radars designed and approved to previous standards will continue to be  used for some years after new standards have been put in place. Retrofitted equipment  must meet the latest standards. IMO radar performance standards previous to those in force on 1 July 2008  require compatibility with existing racons (radar beacons) and at 9 GHz, Search  and Rescue Transponders. 
 How this gain will besplit between the i-fand video amplifiers depends upon such considerations assecond-detector efficiency and the complication involved inbuilding high-gain video amplifiers. Inmost receivers thei-fgain isenough toamplify noise to1or2volts, thus bring- ingitinto the linear region where diode detectors have maximum effi- ciency. This requires again ofaround 106times atthe intermediate frequency. 
 CURRENT SHEARS ASSOCIATED WITH LARGE 
 2013 ,51, 4366–4377. [ CrossRef ] 3. Tan, L.; Ma, Z.; Zhong, X. 
 This might be accomplished with a single-sideband generator (frequency translator) inserted  between the directional coupler and the RF mixer of Fig. 3.17. The frequency translation in the  reference signal path is equivalent to a doppler shift in the antenna path. 
 %RROR #OMPONENTS . 
 The main beam will point in a  direction other than broadside if the relative phase difference between elernents is other than  zero. The direction of the main beam is at an angle 00 when the phase difforcncc is  </J 2rr(d/2) sin 00. The phase at each element is therefore <Pc+ 111¢, where m = 0, I, 2, ... 
 The exact frequencies over which a radar operates should be used in addition to or instead of the letter bands whenever proper to do so. TABLE 1.1 Standard Radar-Frequency Letter-Band Nomenclature* Band designation HF VHF UHF L S C X K11 K Ka V W mmNominal frequency range 3 MHz-30MHz 30 MHz-300MHz 300 MHz-IOOOMHz 1000 MHz-2000MHz 2000 MHz-^OOOMHz 4000 MHz-SOOOMHz 8000 MHz-12,000 MHz 12.0 GHz-ISGHz 18 GHz-27GHz 27 GHz-40GHz 40 GHz-75GHz 75 GHz-IlOGHz 110 GHz-300GHzSpecific frequency ranges for radar based on ITU assignments for Region 2 138 MHz-144MHz 216 MHz-225 MHz 420 MHz-^SOMHz 890 MHz-942MHz 1215 MHz-1400MHz 2300 MHz-2500MHz 2700 MHz-3700MHz 5250 MHz-5925MHz 8500 MHz-10,680 MHz 13.4 GHz-14.0GHz 15.7 GHz-17.7GHz 24.05 GHz-24.25GHz 33.4 GHz-36.0GHz 59 GHz-64GHz 76 GHz-Sl GHz 92 GHz-IOOGHz 126 GHz-142GHz 144 GHz-149GHz 231 GHz-235GHz 238 GHz-248GHz *From IEEE Standard 521-1984. The International Telecommunications Union (ITU) assigns specific fre- quency bands for radiolocation (radar) use. 
 Thegainofabroadside arrayofisotropic elements isapproximately Go= m n(8.26) (Notethatwhenimn=constant, Go=MN.)Thenthenormalized patternofEq.(8.25)canhe expressed as (8.27) (8.28)Thegreaterthegainoftheantenna, thelesstherelative effectoftheerrorsonthesidelobes. Bvsubstituting theradiation intensity ofEq.(8.24)intothedefinition ofgain(ordirecti­ vity)ofEq.(7.3)itcanbeshownthat p.. p.. 
 Also, compared with earlier  years, when racons were essential, many more navigational aids are becoming available  that assist positioning. These include multiple GNSS services, differential GNSS, AIS,  and enhanced VTS facilities. There are also great improvements in onboard naviga - tional aids such as electronic charts and integrated navigation systems. 
 BISTATIC   QUASI 
 Figure 15.22 a shows the surface slope   measured over a short segment of surface in the Gulf Stream,112 with the correspond - ing curvature-squared  profile below. The clutter cross-section defined for this profile  ch15.indd   34 12/15/07   6:17:20 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Dutton: Radio Meteorology, Nat. Bur. Stand. 
 We shall define a layover contour  as the locus of points in 3D space such that an  object at any of the points will be assigned to the same location in a SAR image.  As shown in Figure 17.13, a layover contour is the intersection of a constant-range  sphere of range R and a constant velocity cone of generating angle b  = cos–1 (v/V)  with axis along the platform direction, i.e., a circle of radius R sinb  ahead of the  platform. ( b  > 90 ° corresponds to targets behind the platform.) We shall, there - fore, call the contour the layover circle . 
 TO 
 15, no. 1, p. 10, Grumman Aerospace Corporation, 1979. 
   PP n  *ULYn/CTOBER .   05,3% $/00,%2 2!$!2   {°x£  ! , &RIEDLANDER AND , * 'REENSTEIN  h! GENERALIZED CLUTTER COMPUTATION PROCEDURE FOR  AIRBORNE PULSE DOPPLER RADARS v  )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS    VOL !%3 
 RECEIVE  SWITCHING CAN BE OBTAINED  BY COMBINING TWO HALVES OF A SUBARRAY WITH A FOUR 
 21. M. C. 
 1370–1371, September 1979. 11. B. 
 13.4S.—Reaolved-current PPIusing automatic transmitter triggering. isexactly atcutoff. Thus when asweep isbeing applied this grid will pass upward through itscutoff ppint atexactly the same time that the deflecting current ispassing through zero. 
 Sincethetargetsareundertrack,theirapproximate rangesareknownsothatabeamneedbeformedintheproperdirection onlyduringthetime thatatargetechoisexpected. Inthismanner, severaltargetscanbeheldintrackduringthe interpulse period,provided thephaseshifterscanswitchsufficiently rapidlyandacontrol computer isavailable totakeadvantage oftheinherent flexibility ofthearray. 8.8RANDOM ERRORS INARRAYS Intheanalysis oftheeffectsofreflector-antenna errorsinSec.7.8onlythephaseerrorwas considered. 
 from a turbulent medium is  11 = 0.38C~,l.. -113 (13.34)  where C~. the structure constant. 
 IIB and later H 2S variants, but not on ASV Mk. III. Fishpond [ 2] was used to indicate the presence of targets (enemy ﬁghters or other bombers) at ranges between the aircraft and the ground. 
 n I 1, 'E!ts.f'NJjj II5 I I III112.0-'•951I I"00 LJ,It,.,."41"'IjI[]"fC'rT-n IT["",~Itlr"I " ;I"I~'!"III 11" Ii..1.I·.I'.1...11~ -1.8U'I........a: '"....c2.0"'''·C'''''I.' ..·lii/'1" ',," "I;'1'q~:';'.. ,_~_I ir-J. ! I~_:..._.~.._...l:.'.I.,,'j'" I-r- ,. 
 They can be reflected and scattered; they can be split  up or combined. To the casual layman the ‘speed of  light’ is much the same thing as ‘instantaneous,’ but  the whole science of radar is built up on the microscopic  time intervals which elapse—intervals of so much less  than a second that we split the divisions up into ‘milli-  seconds’ (thousandths of a second) and ‘microseconds’  (millionths of a second). Just why such a fine division  is necessary you will easily see. 
 Ryzhkov, A. Zahrai, and D. Zrnic, “Considerations for polarimetric  upgrades to the operational WSR-88D radars,” J. 
 TION v IN )%%% )NT 2ADAR #ONF 2EC  PP n    $ + "ARTON  h4HE LOW 
 VERSUS 
 Other Ios.~factors. I\.radardesigned todiscriminate between movingtargetsandstationary objects(MTIradar)mayintroduce additional lossoveraradarwithoutthisfacility.TheMTI discrimination technique resultsincomplete lossofsensitivity forcertainvaluesoftarget velocity relativetotheradar. These arecalledblindspeeds.Theblind-speed problem andthe lossresulting therefrom arediscussed inmoredetailinChap.4. 
 38. Lucas, D. L., and J. 
 This is sometimes called apodization. Weighting of the amplitude, as discussed later  in this section, is sometimes desired so as to reduce the time sidelobes accompanying the  compressed waveform.  The reflective-array compressor (RAC) form of SAW device, shown schematically in  Fig. 
 Apr. 21 -23, 1975, Arlington, VA, pp. 128- 131, IEEE Cat. 
 Wu, and R. S. Raghavan, “Low grazing angle bistatic NCRS  of forested clutter,” Electronics Letters -30(18), pp. 
 The use of ASV ‘ﬂooding ’was also tried to overcome the effectiveness of radar warning receivers. This involved using a large number of aircraft at night over theBay of Biscay with ASV switched on, so that the U-boats could not afford to dive on every contact. Meanwhile, Leigh Light aircraft would use ASV only intermittently, in an attempt to catch a U-boat off guard. 
 TIME PROCESSING SEE THE LITERATURE       FOR A DISCUSSION OF 3PACE 
 Examples ofsuchdataaregiveninFigs.2.18to2.20.Theradarcross sectionoftheT-38aircraftathead-on incidence isshowninTable2.1.Thisdatawasalso obtained fromanaircraftinflight.(TheT-38isatwin-jettrainerwitha7.7mwingspananda 14mlength.). Figure 2.17 Comparison of the theoretical and model-measurement horizontal-polarization radar cross  sections of the B-47 medium bomber jet aircraft with a wing span of 35 m and a length of 33 m. Solid curve  is the average of the computed cross sections obtained by the University of Michigan Engineering  Rewarch Institute at a frequency of 980 MHz. 
 Korolyov, E. A. Gelvich, Y . 
 TION 4HIS ALSO MEANS THAT SWITCHABLE LINEAR AND CIRCULAR POLAR IZATION MODES ARE MORE  COMMON ON 643 SYSTEMS (OWEVER  BASIC LOW 
 Geophys. Res. Space Phys. 
 Ó£°{  2!$!2 (!.$"//+  ARE HIGH IN SALT CONTENT OR SALT WATER BECAUSE OF THE HIGH ABSORPTION OF ELECTROMAGNETIC  ENERGY OF SUCH MATERIALS &OR COMPARISON  THE TOTAL TWO 
 132. B. Bergkvist, “Jamming frequency agile radars,” Def. 
 2& LUNAR RADARS ON  #HANDRAYAAN 
 ( b) After denoising. The aspect entropy of the targets is affected by the frequency and polarization of the microwave. The aspect entropy of the targets is also significantly affected by the posture and size. 
 Itisnotusedasofteninmoderntracking-radar applications assomeoftheothertechniques to bedescribed.;Y. 5.3 CONICAL SCAN  A logical extension of the simultaneous lobing technique described in the previous section is to  rotate continuoi~sly an offset ariter~tia bean1 rather than discontinuously step the beam be-  t wceri four discrete positiotis. 'T'liis is kriown as cor~ical sca~rrritry (Fig. 
   
 P. M. Hall, “Effects of the troposphere on radio communications,” London: Institution of  Electrical Engineers, 1979, p. 
 Hardware Implementation Technology.  In the past, implementing a real- time radar digital signal processor typically required the design of a custom comput - ing machine, using thousands of high performance integrated circuits (ICs). These  machines were very difficult to design, develop, and modify. 
 FIG. 5.4 Circuit schematic of an internally input- and output-matched 100-W L-band power transistor. Microwave Field-Effect Transistors (FETs). 
 Haddock, F. T.: Scattering and Attenuation of Microwave Radiation Through Rain. Nat•al Research  Laboratory, Washington, D.C. 
 Ê 
 J. C. Curlander and R. 
 This isbecause the bandwidth for both crystals inseries ismore than ~ofthe carrier frequency. Itcan beshown that, foragiven bandwidth, the transfer impedance isamaximum when the crystal diameter ischosen sothat the active crystal capacity equals thetotal stray capacity. The carrier frequency for mercury lines may range from 5to30 Me/see, with the most usual values inthe range from 10to20Me/see. 
 LeToan et al., “Multitemporal and dual-polarization observations of agricultural vegeta - tion covers by X-band SAR images,” IEEE Trans. on Geosc. and Remote Sensing , vol. 
 typical" reflector antenna the following  expression is sometimes used:  G ~ 20,000  OB<PB (7.8)  where 08 and <J>8 are the half-power beamwidths, in degrees, measured in the two principal  planes. This is a rough rule of thumb that can be used when no other information is available,  but it should not be a substitute for more exact expressions that acount for the actual aperture  illumination.  The definitions of the directive and the power gains have been in terms of the maximum  radiation intensity. 
   
 Consider a CW radar radiating a single-frequency sine wave of  the form sin 2rrt;, r. (The amplitude of the signal is taken to be unity since it does not influence  the result.) The signal travels to the target at a range R and returns to the radar after a time  T = 2R/c. where c is the velocity of propagation. 
 As shown in Figure 9, several centers of severe subsidence areas are distributed along the metro lines such as Region 1. 223. Sensors 2019 ,19, 743 In Region 1 (Figure 9), the subway lines have a high density and two metro lines intersect, namely Metro Lines No. 
 SCALE WAVE MOTIONS ON THE SURFACE  WHILE THE LARGER MEANDERS ARE  INDUCED BY THE VELOCITIES OF LARGE WAVES MOVING THROUGH THE MEASUREMENT CELL 4HE WIND SPEED WAS ABOUT  MS  AND A DOPPLER SHIFT OF  (Z CORRESPONDS TO A RADIAL VELOCITY OF  MS 4HE AVERAGE CLUTTER SPECTRUM EXPECTED FOR THIS WIND SPEED AND GRAZING ANGLE  WITH BANDWIDTH ESTIMATED FROM %Q   IS INCLUDED IN THE SKETCH SHOWN IN &IGURE  4HE LARGE SPECTRAL SPIKE APPEARING IN THE CENTER OF THE DISPLAY IS NO DOUBT DUE TO A WAVE BREAKING IN OR CLOSE TO THE MEASUREMENT CELL 4HE DOPPLER VELOCITY FOR THIS SPIKE SUGGESTS A PEAK SCATTERER VELOCITY ABOUT EQUAL TO THE WIND SPEED  WHICH WOULD CORRESPOND TO THE VELOCITY OF THE LONGEST WAVES ON THE SURFACE !LTHOUGH SUCH EVENTS ARE  RELATIVELY RARE IN A  FIXED AREA OF  M   THEY SHOULD OCCUR  QUITE FREQUENTLY WITHIN A LARGE SURVEILLANCE CELL AND MIGHT OFTEN HAVE LARGE SCATTER 
 C, vol. 105, pp. 93-108, March, 1958. 
 TION OF  D" FOR THIS CASE "UT IF THE SEQUENCE OF PULSE INTERVALS WERE TO BE CHANGED FROM  TO   THE ACTUAL LIMITATION WOULD BE  D"  WHICH IS  D" LESS THAN THAT INDICATED BY THE CURVE 4HIS OCCURS BECAUSE THE PRIMARY MODULATION WITH A  PULSE 
 Ifone istobeused, separate square-wave generators areneces- sary toswitch the range-marker circuit and toperform the other func- tio&. The former square-wave generator must betriggered directly as 1Atrigger generator forthemodulator issometimes housed with theindicator equipment forconvenience, buttheactual synchroni~atiOn isaccomplished bYtrans- mitting themodulator pulse tothetimer proper. This case isfunctionally identical with that inwhich thetrigger source isphysically part ofthemodulator. 
 D. Campbell and S. H. 
 SCAN PROBABILITY OF DETECTION ON THE  KTH SCAN 4HE ACCUMULA 
 23.6 RESEARCHAPPLICATIONS Operational meteorological radars are designed for reliability and simplicity of operation while providing the performance needed for operational applications. Research radars are considerably more complex, since cutting-edge research re- quires more detailed and more sensitive measurements of a multiplicity of vari- ables simultaneously. In the research community, multiple-parameter radar stud- ies, multiple-doppler radar network studies, and plans for airborne and space- borne radars are all receiving considerable attention. 
 OFF BETWEEN PICTURE ELEMENT DIMENSIONS AND NONCOHERENT AVERAGING IN  SIDE 
 Gambardella, A.; Nunziata, F.; Migliaccio, M. A physical full-resolution SAR ship detection ﬁlter. IEEE Geosci. 
 IT-6, pp. 269·308,  April, 1960.  38. 
 RECEIVER PAIR AT EACH ELLIPSE FOCI 4HE INTERSEC 
 The latter is the more usual of the two possible coordinate systems since it is easier for the  microwave engineer to measure the VSWR and the position of the voltage-standing-wave  minimum (or phase) than it is to measure the conductance and susceptance directly. The  radial coordinate can also be specified by the reflection coefficient r of the load since the  VSWR p and reflection coefficient are related by the equation Ir I = (p - 1 )/(p + 1 ). The  center of the Smith chart (Rieke diagram) corresponds to unity VSWR, or zero reflection  coefficient. 
 I!.. and <;. Randig: Terrain Backscattering Characteristics at Low Grazing Angles for .Y-  arid S-13and. 
 The above attributes of the millimeter-wave region suggest as potential applications  low-angle tracking, interference-free radar, ECCM, cloud-physics radar, high-resolution radar,  f uzes, and missile guidance. These, as well as other applications. have not been widely  employed because or the concomitant limitations that occur with operation at millimeter  waves. 
 Consider alinearin-phase receiving antenna oflengthD,orarectangular receiving aperture ofwidthDasshowninFig.11.6.Theamplitude distribution acrosstheaperture asa. Figure 11.6 Rectangular receiving  apcrtilrc of width D and arnplitudc  distribt~tion A(.r) giving rise to radiated  I pattern G,,(O)  function of x is denoted A(x). The (voltage) gain as a function of the angle 0 (od-dimensional  radiation pattern) in the xz plane is proportional to  When the angle 0 is small, sin 0 0, and Eq. 
 LIKE CHARACTERISTICS AND THE RECEIVED SIGNAL IS  CROSS 
 ltd)  of merit. A more suitable reciprocal device that overcomes the limitations of previous recipro­ cal ferrite phase shifters in the d11al-mode phase shifter based on the principle of the Faraday  rotor.25·33·35-37 It is competitive with the toroid phase shifter, especially at the higher micro- wave frequencies. ,~  In the dual-mode phase shifter the linearly polarized signal in rectangular waveguide at  the left-hand port in Fig. 
 Many aircraft have approximately this characteristic at microwave frequencies, and large complicated targets are usually of this nature. (This result is predicted, for such targets, by the central limit theorem of probability theory.) The second distribution, Eq. (2.24), corresponds to that of a target having one main scattering element that predominates together with many smaller independent scattering el- ements. 
 A simple example is a combined X-band and Ka-band monopulse pa- raboloid antenna radar. Separate conventional feeds are used for each band, with the Ka-band feed as a Cassegrain feed and the X-band feed at the focal point.15 The Cassegrain subdish is a hyperbolic-shaped grid of wires reflective to parallel polarization and transparent to orthogonal polarization. It is oriented to be trans- parent to the X-band focal-point feed behind it and reflective to the orthogonally polarized Ka-band feed extending from the vertex of the paraboloid. 
 Klystrons and TWTs are called linear-beam tubes because the direction of the dc electric field that accelerates the electron beam coincides with the axis of the magnetic field that focuses and confines the beam. This is in contrast to crossed- field tubes, such as magnetrons and CFAs, in which the electric and magnetic fields are at right angles to each other. Since there are a number of excellent references that describe the theory and operation of RF amplifier tubes,2^-16~18 this discussion will be limited primarily to system considerations in selecting and using microwave amplifier tubes in ra- dar transmitters. 
 26.6  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 to the Earth’s dimensions, and little energy is diffracted. At optical frequencies or  very short radar wavelengths, the optical horizon represents the approximate boundary  between regions of propagation and no propagation. Tropospheric Scatter. 
 R. L.: Passive ECM Applied to False Target Elimination, Record oftlre IEEE 1975 It~terrrci-  tic~rrtll Radar Cot!leretrce. pp. 
 Aslow rate ofcharge iseasily obtained byusing alarge inductance LO, which isalso needed toprevent avirtual short circuit across theenergy source every time thenetwork isdischarged. Induct- ance charging isused inpractically allline-type pulsers, because ithas the advantage ofhigh efficiency and permits charging thepulse-forming network toavoltage nearly double that ofthepower supply, asshown below. Consider first ad-cpower supply voltage ofnegligible resistance, in series with aninductance, aswitch, and acapacity Coriginally dis- charged, The energy supplied bythe source inatime Tafter closing Itheswitch isV.S~~idt. 
 ch08.indd   44 12/21/07   10:24:08 AMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 
 CLUTTER ENVIRON 
 Davies, D. E. N., and H. 
 ERS AMPLIFIERS ARE COMBINED INTO MODULES AND MODULES ARE COMBINED INTO SYSTEMS 'ENERALLY  THE COMBINING TAKES ON ONE OF TWO DIFFERENT CONFIGURATIONS USING EITHER SPACE 
 r  \SIN \P    %QUATION   MAY AGAIN BE APPROXIMATED BY THE &OURIER TRANSFORM OF THE ILLUMINA 
 FORM VIRTUAL PATH TRACE  3NELLS LAW FOR A SPHERICALLY SYMMETRIC MEDIUM  IS SEQUENCED THROUGH ELEVATION RADIATION ANGLES IN  n INCREMENTS 4HIS PROCESS IS  INCREMENTED IN  
 The solid curves are  exact valuefcomputed by Hadd~ck.".~~ The Rayleigh scattering approximation is seen to be  satisfactory over most of the frequency range of interest to radar.  The reflectivity factor Z of Eq. (13.19), which was defined as the sum of the sixth power of  tlie particles' diameter per unit volume, was based on the assumption of Rayleigh scattering. 
 In spite of this fact, the radar or part of its aperture is often  used for a data link, especially to missiles on the fly and in response to peacetime  air traffic control interrogations. Pulse amplitude (including on-off), pulse position,  phase shift, and frequency shift modulation are commonly used. Links may be unidi - rectional or bidirectional. 
 Frequency  (b)  Frequency  (c)  Figure 4.16 (a) Frequency-response of a single-delay-line canceler for f, = 1/T,; (b) same for fp = l/Tz;  (c) composite response with TIIT, = $.  repetition frequencies are in the ratio of 5 : 4. Note that the first blind speed of the composite  response is increased several times over what it would be for a radar operating on only a single  pulse repetition frequency. 
 Ryde and Ryde45 calculated the effects of rain on microwave  propagation and showed that absorption and scattering effects of raindrops become  more pronounced at the higher microwave frequencies, where the wavelengths and  the raindrop diameters are more nearly comparable. In the 10-cm band and at shorter  wavelengths, the effects are appreciable, but at wavelengths in excess of 10 cm, the  effects are greatly decreased. It is also clear that suspended water (cloud) droplets and  rain have an absorption rate in excess of that of the combined oxygen and water-vapor  absorption.46 In practice, it has been convenient to express rain attenuation as a function of the  precipitation rate R, which depends on the liquid-water content and the fall velocity of  the drops, the latter in turn depending on the size of the drops. 
 They soon appreciated that the new airborne systen  with very little modification might be used to detect no  air targets, but ground targets. ‘Ground returns,’ th  . THE MAGIC EYE 137  wasteful, troublesome echo returns from the ground,  inseparable from early types of airborne fighter equip-  ment, where part of the radiation reaches the horizon  and the ground, and so clutters up part of the display  by unwanted ‘earthy’ echoes, might at last be harnessed  to use. 
 Generally, the signal bandwidth of a simple pulse of sine  wave of duration t is 1/t. (Pulse compression waveforms, discussed in Chapter 8, can  have much greater bandwidth than the reciprocal of their pulse width.) Large band - width is needed for resolving targets in range, for accurate measurement of range to  a target, and for providing a limited capability to recognize one type of target from  another. High range resolution also can be useful for reducing the degrading effects  of what is known as glint in a tracking radar, for measuring the altitude of an aircraft  based on the difference in time delay (range) between the two-way direct signal from  radar to target and the two-way surface-scattered signal from radar to surface to target  (also called multipath height finding ), and in increasing the target-signal-to-clutter  ratio. 
 Time delay steering can be achieved at the subarray level  through the use of digital time delays. The multiple beam cluster is formed by digitally  combining the subarrays to form simultaneous beams that are offset from one another.  In practice, DBF is frequently implemented at the subarray level rather than the ele - ment level due to the size, weight, and high cost of digital receivers. 
 57. Berrie, D. W.: The Effects of Pseudo-Random Noise Upon Radar System Performance, Aeronaurrcul  Systems Division, Wright-Patterson Air Force Base, Ohio, ASD-TR-74-23, August, 1974. 
 IEEE Geosci. Remote Sens. Lett. 
 When directive elements are used, the resultant array antenna radiation pattern is  G(O) = G (0). si!.12 (1}'~(d~~L~i-~_qL = G (O)G (0)  e N2 sin2 [rr(cl/J) sin O] e a (8.6)  where Gr(O) is the radial ion pattern of an individual element. The resultant radiation pattern  is the product of the element factor Ge(O) and the array factor G0(0), the latter being the pattern  of an array composed of isotropic elements. 
 It has also been considered for use in a low-signal  density environment when the criterion is that either no signal is present or one signal of fixed  and specified level is present and equally likely to be in any range inter~al.~'*~~  The term sequential detection is sometimes used synonymously with Sequential Observer.  Sequential detection has also been used to describe a two-step, or two-stage, detection process  DETECTION OFRADAR SIGNALS INNOISE381 ifchoiceJisindicated, noconclusive decision canbereachedandanotherobservation ismade. ThethreechoicesareagaineX'aminedon thebasisofthecombined observations. 
 Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars.  SPACE-BASED REMOTE SENSING RADARS  18.436x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 18 processed in ground-based facilities, since the more complicated waveforms from icy  surfaces require iterative development of suitable processing algorithms by investiga - tors prior to retrieving the desired information. The conventional mode is used for the  open ocean (for calibration and sea-surface height reference purposes) and the central  continental ice sheets that are relatively level. 
 J.L.:AnAnalytical Approach totheCoverage ofaHemisphere byNPlanarPhased Arrays,IEEETrailS.,vol.AP-15.pp..167-.171. May,1967. 125.lIering.K.II.:Optimization ofTiltAngleandElement Arrangement forPlanarArrays,MicrvwQl'e J.,vol.14,pp.41-51.Jan.,1971. 
 H. Tabeling: Tracking 1nstrumentati-m and Accuracy on the.Eastern Test  Range, IEEE Trans., vol. SET-11, pp. 
 Additional filters foreliminating “window” signals orrain clutter were also provided and could beswitched inwhen desired. These filters had much less attenuation than the clutter filters, but the at- tenuation extended over awider frequency range, designed toexclude doppler frequencies due tomotion of“window.” Although theaudio amplifier began tocutoffrapidly above 1000 cps, and the strength ofthe harmonics ofj,decreased fairly rapidly, itwas found necessary tohave infinite attenuation filters at2000 and 3000 cps, 1See Sec. 6.20, Vol. 
 One such antenna is il- lustrated in Fig. 6.18. Monopulse Feeds,22"25 Monopulse is the most common form of multiple- beam antenna, normally used in tracking systems in which a movable antenna keeps the target near the null and measures the mechanical angle, as opposed to a surveillance system having overlapping beams with angles measured from RF difference data. 
 GER THAN FOR SURFACES  SOMETIMES BEING ONLY  D" DOWN 3CATTER DEPENDS ON THE DIELECTRIC CONSTANT  WHICH DEPENDS ON MOISTURE CONTENT 4HUS   SCATTER FROM WET SOILS AT ANGLES OFF VERTICAL IS USUALLY MUCH HIGHER THAN FROM DRY SOILS &IGURE  SHOWS THIS  4HE EFFECT CAN BE MANY DECIBELS  D" IN THE FIGURE  6EGETATION CANOPIES OVER SOIL CAN CONTRIBUTE TO SCATTER IN THE VARIOUS WAYS SHOWN  IN &IGURE  &IGURE  SHOWS AN EXAMPLE -OST OF THE SCATTER FROM  THE ENTIRE PLANT CAME FROM THE TOP LEAVES  WITH ENOUGH ATTENUATION THERE TO REDUCE   . £È°ÎÈ  2!$!2 (!.$"//+  THE SCATTER FROM STEM  BOTTOM LEAVES  AND SOIL TO MEASURABLE BUT NEGLIGIBLE SIZE  7HEN THOSE LEAVES WERE  ABSENT  THE SIGNALS SCATTERED  FROM THE SOIL AND LOWER PARTS  OF THE PLANT WERE ABOUT EQUAL TO EACH OTHER AND WERE MUCH LARGER THAN WHEN LEAVES WERE PRESENT &)'52%     "OUNDARIES OF MEASURED RADAR DATA  A  HORIZONTAL POLAR 
 156. Whicker, L. R., and R. 
 Although it may have been desirable to go to a higher duty cycle and lower peak power to make the solid-state retrofit easier, the Navy preferred not to have to modify the rest of the system. The 250-kW peak power transmitter uses a total of 128 high-power amplifier mod- ules, which, along with power combining, predrivers, drivers, and control circuitry, are housed in three separate cabinets. There are 112 final power output modules ar- ranged in two groups of 56. 
 IEEE , vol. 87, pp. 702–718, May 1999. 
 26, pp. 1209–1218, 1991. 192. 
 From the relationship described above and assuming the A/D converter limits the  dynamic range, the A/D converter size can now be determined. Additional margin to  allow for main-beam clutter fluctuations above the mean value also needs to be con - sidered. Since main-beam clutter time fluctuation statistics are highly dependent on  the type of clutter being observed, such as sea clutter or clutter from an urban area, and  are generally unknown, a value of 10 to 12 dB above the rms value is often assumed  for the maximum peak level (this also includes the 3 dB difference between the rms  and peak values of a sinusoidal signal). 
 34. Mavroides, W. G.. 
 The measurement angles shown in Table 25.2 are defined in Fig. 25.9, which is a clutter-centered coordinate system similar to those used in all the measurement programs. Because terrain and sea are reciprocal media, 0, and 05 are inter- changeable in the subsequent data.103 The Pidgeon data was analyzed by Domville109 and Nathanson.116 Vander Schurr and Tomlinson117 analyzed the Larson and Cost data. 
 09 == squint  angle. TRACKING RADAR 165  squinted beams is not an easy task. Nutation, which preserves the plane of polarization, is even  more difficult. 
 At the lower end of the trace there was a region with no returns and the ﬁrst return corresponded to the ground immediately below the aircraft (received through the antenna sidelobes), hence thedisplay is called the height tube. When the antenna was scanning, large targets at long range would only be seen as a ﬂeeting response on the height tube. The height marker was shown as another blip (to the left). 
 Thethickertheduct,thelowerthefrequency thatcanhepropagated, ascanbeseenfrom Eq.(12.IJ).Thusthelowermicrowave frequencies (belowLband)arcnotusuallystrongly affected bytheevaporation duct.Theupperfrequency limitforducting isdetermined bythe increased attenuation duetoroughness oftheseaandhyahsorption ofekctromagne~ic energy inthevicinityofthcwatervaporresonance at22GHz.Thusthercisprobably annptintllm frequcncy fortheutilization ofductedpropagation. Inaductwith('(lI/lI'Il't( tlapping ofthe electromagnetic energy.thecylindrical spreading oftheenergyradiatd hyapoi'llsource resultsinthepowerdensitydecreasing asR-I,whereR=range.insteadofR1aswithfree spacepropagation. Theenergyisseldomcompletely trapped. 
 4(% 
     
 4(% 
 Therefore. there will be some angle at which these two counteracting effects result in  maximum efficiency. This is illustrated in Fig. 
 69. Oekcfi. G .. 
 6. D. C. 
 ALLY VARIES LINEARLY WITH THE DATA SAMPLE RATE &OR THIS REASON  IN MOST SYSTEM APPLICA 
 The RF energy  from the row feeds is combined in space to form the radiated beam. Unlike a tube  transmitter, which operates at high peak power and low duty factor, the power mod - ules operate at low peak power and high duty factors (10% to 20%). Long-duration  pulses are transmitted and then compressed during receive to obtain the required  range resolution. 
 ING IS A TERM INVENTED BY THE 5+ DURING 77)) FOR RADAR POINTING OF ANTIAIRCRAFT GUNS  2ANGE ACCURACY IS AT LEAST AN ORDER OF MAGNITUDE BETTER THAN ANGLE ACCURACY 3OME METHOD MUST BE USED TO IMPROVE ANGLE ACCURACY FOR WEAPON DELIVERY !N EXAMPLE PRO 
 Low sidelobes are generally desired for radar applications. If too large a portion of the  radiated energy were contained in the sidelobes, there would be a reduction in the main-beam  energy, with a consequent lowering of the maximum gain.  No g~1eral rule can be given for specifying the optimum sidelobe level. 
 CODED WAVEFORMS OR NONLINEAR FREQUENCY MODULATION WAVEFORMS  MATCHED FILTER PROCESSING ALONE ACHIEVES ACCEPTABLE TIME SIDELOBE LEVELS (OWEVER  FOR THE CASE OF A LINEAR FREQUENCY MODULATION WAVEFORM  THE MATCHED FILTER IS GENERALLY FOLLOWED BY A WEIGHTING FILTER TO PROVIDE A REDUCTION IN TIME SIDELOBE LEVELS )N THIS CASE  THE WEIGHTING FILTER RESULTS IN A SIGNAL 
 GATE  STEALER PULLS THE RADAR 
 The relative amplitudes of the two waves and the phase relationship between them can  assume any values. If the amplitudes of the two waves are equal, and if they are 90" out of  (time) phase, the polarization is circular. Circular polarization and linear polarization are  special cases of elliptical polarization. 
 Hybrid tracking system. Conopulse86 and "scan with compensation "8 7 are the names given 10  a hybrid tracking system that is a combination of monopulse and conical scan. Two squinted  beams, similar to those of a single angle-coordinate amplitude-comparison monopulse, are  scanned (rotated or nutated) in space around the boresight axis. 
 Letters , vol. 25, pp. 4035––4038, 1998. 
 New York: IEEE Press, 1988,  pp. 272–276. 16. 
 LIVED STORMS AND CLOUD SYSTEMS  THEREBY ALLOWING MORE COMPLETE STUDIES OF EVOLUTION DURING VARIOUS PHASES OF THE SYSTEM  .#!2S %LDORA AIRBORNE DOPPLER RADAR SYSTEM  SHOWN IN &IGURE   CONSISTS  OF TWO SLOTTED WAVEGUIDE FIXED 
 The modern aircraft carries a wealth  of radio and radar equipment. This composite picture shows  sixteen major electronic devices to aid pilot and navigator.  (1) H2S, with an impression of a typical radar ground map as  seen on the screen. 
 The  short-duration, large-amplitude" spike." at the leading edge of the leakage pulse is the result of  the finite time required for the TR to ionize or break down. Typically, this time is of the order  of 10 nanoseconds. After the gas in the TR tube is ionized, the power leaking through the tube  is considerably reduced from the peak value of the spike. 
 To this there must be added a wind-drift velocity of about 3 percent of U and a fixed scatterer velocity (which appears to be about 0.25 m/s in the X- and C-band measurements51'52'54). Summing these components yields the virtual doppler velocity at the peak of the clutter spectrum for the particular case of a vertically polarized, X- or C-band radar looking upwind at low grazing angles: VviT « 0.25 + 0.13t/ m/s (13.11) (As noted earlier, care must be taken whenever wind speed is used to parame- terize a process that depends on waveheight. There is an unambiguous relation only for a fully developed sea in the absence of swell.) The remaining properties . 
 S. Marshall and W. Hitschfeld, “The interpretation of the fluctuating echo for randomly distrib - uted scatterers,” Pt. 
 Donohue and F. M. Ingels, “Ambiguity function properties of frequency hopped radar/sonar  signals,” Proc. 
 Singh, and A. L. Gray, “Seasonal and regional variations of active/passive  microwave signatures of sea ice,” IEEE Trans. 
 175.  7. D. 
 In the case of phase-coded transmissions, the duration of the subpulses is the time parameter. This is equivalent to the spacing of the subpulses with one exception: the quadriphase code5'6 employs half-cosine subpulses with 6 dB width equal to four- thirds of subpulse spacing. One of the virtues of the quadriphase code is the unusu- ally low mismatch loss, owing to the fact that the impulse response of the gaussian filter is an excellent approximation to the subpulse shape. 
 While Fig. 17.18 is for a medium-PRF radar, similar curves result for a high-PRF radar. Also shown in Fig. 
 CM CHANGE IN SEA 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar.  TRACKING RADAR  9.416x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 Theoretically, the coupling to cross-polarized energy is zero when the source is pre - cisely on axis and increases with displacement from the axis.51 The cross-polarization  error in a tracking radar system is pure crosstalk so that a small true tracking error in  one tracking coordinate causes the antenna to move in the other coordinate. The error  in the second coordinate then causes the antenna to move farther from the source in the  first coordinate. 
  
 This is illustrated in Figure 16.30,133  which shows these effects with measurements from plowed fields. At 1.1 GHz, the  signal changed 44 dB between 0 and 30° for the smoothest field and only 4 dB for the  roughest. At 7.25 GHz the smoothest field was rough enough to reduce the variation  to 18 dB. 
 PULSE CANCELER PARAMETERS .   -4) 2!$!2  Ó°{£ IN THE VELOCITY RESPONSE CURVE &OR MANY APPLICATIONS  A FOUR 
 In general, distortion of a phased array antenna will cause a decrease in antenna gain. Figure 22.3 shows the effect of random phase errors caused by the distortion € when the error correlation interval is large with respect to a wavelength. It is seen from Fig. 
 This is because the single-delay canceler requires the best match between the actual pattern and the required pattern near boresight, whereas double cancellation requires the best match on the beam shoulder. Step-scan compensation usually requires the difference-pattern peaks to be near the nulls of the sum pattern to match. Grissetti et al.13 have shown that for step-scan compensation the improvement factor for single-delay cancellation increases as a function of the number of hits atn = NUMBER OFHITS PER BEAMWiDTH FIG. 
 Rudge and N. A. Adatia, “Offset parabolic reflector antennas: A review,” Proceedings  IEEE , vol. 
 Phase detection occursasintheconventional monopulse. Another single-channel systemSCAMP converts thesumandthetwodifference signalstodifferent IFfrequencies andamplifies them simultaneously inasingle,wide-band amplifier.20Theoutputishard-limited toprovide the effectofaninstantaneous AGe.Thethreesignalsafterlimiting are separated bynarrowband filtersandthenconverted tothesameIFfrequency forfurtherprocessing. Thehard-limiting, however, causescross-coupling between theazimuth andtheelevati.on error-signal channels andcanresultinsignificant error.21Two-channel monopulse receivers havealsobeenusedby combining thesumandthetwodifference signalsinamanner suchthattheycanbeagain resolved intothreecomponents afteramplification.1.22 Thepurpose inusingone-ortwo-channel monopulse receivers istoeasetheproblem associated withmaintaining identical phaseandamplitude balanceamongthethreechannels oftheconventional receiver. 
 Although electromechanical shifters are not now widely used, they are described  here to illustrate the variety of devices that might be employed in array antennas.  One or the earliest and simplest forms of electromechanical phase shifters is a transmis­ sion line whose length is varied mechanically, as with a telescopic section. This is called a line  srretclicr. 
 Silver2 describes the procedure to determine the contour for a cosecant-squared beam graphically. However, with modern computers arbitrary beam shapes can be approximated accurately by direct integration of the reflected primary pattern. In so doing, the designer can account for the approximations to whatever accuracy he or she chooses. 
 Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 
 It is also  justified when automatic (electronic) detections are made without the aid of an operator.  When the operator does introduce loss into the system, it is not easy to select a proper value to  account for it. The better action is to take steps to correct loss in operator performance rather  than tolerate it by including it as a loss factor in the radar equation. 
 POINT OF THE REFERENCE WAVEFORM &OR THE CASE SHOWN  WHERE THE  2& CARRIER FREQUENCY  IS ABOVE THE CARRIER FREQUENCY OF THE REFERENCE WAVEFORM  A POSITIVE TIME DELAY RESULTS  IN A NEGATIVE FREQUENCY OFFSET 4HE SIGNALS AT THE CORRELATION MIXER OUTPUT ARE THEN RESOLVED IN THE FREQUENCY DOMAIN BY SPECTRAL ANALYSIS PROCESSING  ! TYPICAL IMPLEMENTATION FOR THE SPECTRAL ANALYSIS PROCESSING INCLUDES A SECOND  FREQUENCY CONVERSION FOLLOWING THE #- TO A FINAL INTERMEDIATE FREQUENCY )&   ANTI 
 Lee (eds.), Antenna Handbook: Theory, Applications and Design , Reflector  Antennas , Chapter 15, New York: Van Nostrand Reinhold Co. Inc., 1988. 15. 
 Tlle cathode in a crossed-field tube is also known as the sole.  (Tlie terrri  sol^. wllicli nicails yr.orrrlti /~lirte, comes frorn the Frencll, wllo did much of tlie early  ivork on crossed-field devices.) In some crossed-field devices the sole does not emit electrons,  arid a separate crnittilig catliode is used. 
 CORRELATION IS NOW FEASIBLE TO IMPLE 
 26. Woodward, P. M.: "Probability and Information Theory with Applications to Radar," McCiraw-llril  Book Company, New York, 1953. 
 Accurate receiver gain control  is required for a variety of reasons that include target radar cross-section measure - ment, monopulse angle accuracy, maximizing the receiver dynamic range, and noise  level control. Digital gain control permits the calibration of receiver gain by inject - ing test signals during radar dead time or during some scheduled calibration interval.  Calibration coefficients can be stored as a function of commanded attenuation, operat - ing frequency, and temperature as needed. 
 PLUS MODEL MENTIONED  ABOVE PROVIDES FURTHER CREDIBILITY !LTHOUGH SCATTERING FEATURES HAVE BEEN INTRODUCED MAINLY IN CONNECTION WITH  LOW 
 Bracewell, R. N.: Tolerance Theory of Large Antennas, IRE Trans., vol. AP-9, pp. 
 While there are several assessment systems in use within the U.S. and in  various other countries, the following discussion is limited to AREPS. It is used  extensively throughout the U.S. 
 DRIVE ELECTRIC MOTORS WHERE THE ANTENNA MECHANICAL AXIS SHAFT IS PART OF THE ARMATURE  AND THE MOTOR FIELD IS BUILT INTO  THE SUPPORT CASE 4HE DIRECT DRIVE IS HEAVIER FOR A GIVEN HORSEPOWER BUT ELIMINATES  &)'52%     A  !NGLE ERROR INFORMATION CONTAINED IN THE ENVELOPE  OF THE RECEIVED PULSES IN A CONICAL 
 ch15.indd   39 12/15/07   6:17:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Sea Clutter. 
 The echo from a single  bird is also an example of point clutter. When clutter echoes are sufficiently intense and  extensive, they can limit the sensitivity of a radar receiver, and thus determine the range  performance. In such circumstances, the optimum radar waveform and receiver design can be  quite different than when receiver noise alone is the dominant effect. 
 Y PLANE AT  Z    &IGURE   BY ASSUMING COHERENT REFLECTION OF SPHERICAL RADIATION  FROM A FEED AT THE FOCAL POINT 4HE FIELD DISTRIBUTION IS THEN USED TO COMPUTE THE FAR 
 Two-frequency lntemogation.-Another method related tothe use of groups ofpulses isthe use ofcoincident interrogation attwo different frequencies. The two pulses may beactually coincident, orone delayed with respect tothe other byany fixed amount. Both the value ofthe second frequency and that ofthedelay give additional coding possibility ies. 
 Zebker, “Polarimetric radar measurements of a forested area  near Mt. Shasta,” IEEE Trans. on Geosc. 
   05,3% $/00,%2 2!$!2   {°{Î %Q  ASSUMES AN UNMODULATED  RECTANGULAR TRANSMIT PULSE SHAPE WITH THE RECEIVE  GATE MATCHED TO THE TRANSMIT PULSE WIDTH 4HERE IS NO RANGE GATE OVERLAP 4HE FIRST GATE OF THE . RANGE GATES ARE BLANKED FOR THE TRANSMIT PULSE !S SHOWN IN &IGURE   THIS  APPROXIMATION IS ONLY VALID FOR A 0 D NEAR  4HERE ARE SEVERAL OTHER DETAILS THAT HAVE NOT BEEN INCLUDED IN &IGURE  !S SHOWN  IN &IGURE   A PORTION OF THE FIRST VALID RECEIVE RANGE GATE AND POSSIBLY A PORTION OF THE LAST RANGE GATE IN THE )00  IS TYPICALLY BLANKED TO AVOID RECEIVING TRANSIENTS OF THE TRANSMIT 
   PP n  *ULY   6 'REGERS (ANSEN  h#ONSTANT FALSE ALARM RATE PROCESSING IN SEARCH RADARS v IN  2ADAR  0RESENT  AND &UTURE  )%% #ONF 0UBL NO   ,ONDON  5+  /CTOBER   . +HOURY AND * 3 (OYLE  h#LUTTER MAPS $ESIGN AND PERFORMANCE v IN  )%%% .AT 2ADAR #ONF   !TLANTA  '!    ' 6 4RUNK ET AL  h&ALSE ALARM CONTROL USING DOPPLER ESTIMATION v  )%%% 4RANS !EROSPACE AND  %LECTRONIC 3YSTEMS  VOL !%3 
 ORDER DOPPLER SPECTRUM IS USUALLY SOME n D" WEAKER THAN THE FIRST 
 Whenthemotoris upto speed, this resistor isshunted out byacontactor (see Fig. 14.4. )This reduces theinitial starting current, but thecurrent again rises sharply if the secondary contactor closes too soon. 
 It will completely arouse the water waves with a phase velocity nearly equal to the wind speed. It will also completely arouse all the ocean waves of lower velocities. Figure 24.2« gives an example of the spectrum as derived from a measurement of waveheight versus time at a par- ticular point. 
 TRACK GEOID GRADIENTS )T ALSO IS STANDARD PRACTICE TO CONSTRAIN AN ALTIMETERS CROSS 
 For simplicity only the search processing is shown. Duplexer. The duplexer in a pulse doppler radar is usually a passive device such as a circulator which effectively switches the antenna between the transmit- ter and receiver. 
 TO 
 BIT FREQUENCY ACCU 
 I. Abramovich, “Investigations with SECAR— A bistatic HF surface wave radar,” Proc. IEEE Int. 
 Aconsiderable time delay may beinvolved, but inmany cases this can beobviated byhaving thesweep oftheinterrogating radar started bythe last ofthe group ofinterrogating pulses. One ofthe prinrip:d benefits. 264 RADAR BEACONS [SEC. 
 Typical time-sidelobes with  the nonlinear FM waveform were 58 dB below the peak response. It might be noted that  Cole et al.55 state that in order “to ensure continued availability of the power transistors  required to produce the power amplifier panels, Northrop Grumman has developed an  in-house manufacturing capability for high-power S-band transistors.” The third approach to employing solid-state transmitters is the active aperture phased  array radar. At each element of a phased array radar antenna is a solid-state module,  known as a T/R module,  that contains a transmitter, receiver, and duplexer. 
 242-246. May.1960. 58.Beckmann. 
 TURE ARE THE SAME SO THAT THE OUTPUT OF THE ANGLE 
 ( a) Traditional imaging processing; ( b) imaging processing of proposed approach (mixed Euclidean norm); complex images of channels 1 and 2 (ﬁrst and second layers); interferometric phase images (third layer); ﬁnal 3-D imaging results (last layer). 179. Sensors 2018 ,18, 3750 5. 
 A repeater can be very effective against an unprepared radar system. Repeater jamming,  however, is generally easier to counter than is noise jamming. Against a properly prepared  radar, repeater jamming can be made to have only minimal effect. 
 Skolnik, M. L: Fifty Years of Radar, Proc. IEEE, vol. 
 FED REFLECTOR MODEL AND PATTERNS.   2%&,%#4/2 !.4%..!3   £Ó°Îx CODE PORTION OF THE 3!4#/- 7ORKBENCH IS BASED UPON THE LEGACY .%# 
 Thus low  sidelobes and good aperture efficiency run counter to one another.  A word of caution should he given concerning the ability to achieve in practice low  sidelohe levels with extremely tapered illuminations. It was assumed in the computation of  these radiation patterns that the distribution of the phase across the aperture was constant. 
 Let g=4rdK/~ bethedamping ofawave forone passage from thefront toback surface and return. Let @=-lmd,’x bethe change in phase forthesame passage. Finally letpbethetransmission coefficient ofthefront surface. 
 At10 Me/see the value is22,000 ohms foranactive area of1in.2 With this area thetotal capacity ateach crystal isabout 50ppj, and thebandwidth isthen 3.8Me/see perend ifRI=Rz=300ohms. These values give atransfer impedance of8.6ohms. Itwill benoticed that noaccount is taken ofthe inherent bandwidth ofthe crystals. 
 Because of the wide variation of cross-section values of real targets, the range performance of a radar system is often stated for a particular target-cross-section assumption. A favorite value for many applications is 1 m2. This represents the approximate cross section of a small aircraft, nose aspect, although the range for different "small" aircraft may be from less than 0.1 m2 to more than 10 m2. 
 For such targets, the phase fluctuation from pulse to pulse is small. This type of integration is being em- ployed to an increasing extent in modern systems when the utmost sensitivity is important and when fast fluctuation is not expected. *Chapter written by Lowell W. 
 3.Fixed ground beacons.radar sets can sometimes conveniently be ofranges toportable beacons placed at The beacon ishere the radar analogue ofthe old-fashioned lighthouse. Since range tothe beacon is measured aswellas itsbearing, observation ofasingle beacon gives two intersecting lines ofposition and afixmore accurate than is customarily obtained byother methods. Shipborne beacons. 
 SIDERATIONS   DIFFERING REQUIREMENTS IN TERMS OF ACCEPTABLE PROPAGATION QUALITY  AND SO ON ! COMMON EXAMPLE IS THE DESIRE TO SEARCH FOR SHIPS AND AIRCRAFT CONCURRENTLY !CCORDINGLY  OPTIMIZATION OF THE ALLOCATION OF RESOURCES BECOMES A CRITICAL ISSUE  WITH SIGNIFICANT IMPLICATIONS FOR THE WAY SKYWAVE RADARS OPERATE /NE APPROACH TO FITTING MORE TASKS INTO THE TIME AVAILABLE IS TO PARTITION THE RADAR  TRANSMIT AND RECEIVE ARRAYS  TOGETHER WITH THE TRANSMITTER MODULES AND RECEIVERS  SO THAT WHEN CONDITIONS ARE FAVORABLE  THE PARTITIONS CAN OPERATE AS INDEPENDENT RADARS WITH REDUCED SENSITIVITY AND RESOLUTION &OR EXAMPLE  THE *INDALEE AND */2. RADARS ARE DYNAMICALLY RECONFIGURABLE AS FULL OR HALF RADARS !LTERNATIVELY  IT MAY BE ACCEPT 
 log. (26.4) p = atmosphere’s barometric pressure in millibars T = atmosphere’s absolute temperature in Kelvin rh = atmosphere’s relative humidity in percent ch26.indd   3 12/15/07   4:52:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 !ZIMUTH 
 96. Trunk. C;. 
 itisnot alwaysdesirable toemployalow-noise firststageinradar.Thereceiverinputcansimplybe themixerstage.especially inmilitary radarsthatmustoperate inanoisyenvironment. Although areceiver withalow-noise front-end willbemoresensitive, themixerinputcan havegreaterdynamic range.lesssusceptibility tooverload, andlessvulnerability toelectronic interference. Themixerandlocaloscillator (LO)converttheRFsignaltoanintermediate frequency (IF)./\"typical" IFamplifier foranair-surveillance radarmighthaveacenterfrequency of30 or60MHzandabandwidth oftheorderofonemegahertz. 
 3.1  3.2 Noise and Dynamic-Range Considerations   ............  3.3  Definitions  .........................................................  3.4 Evaluation  ......................................................... 
 SELECT TARGETS WITHIN THE OPERATIONAL DISPLAY AREA AND TO DRAW USER 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 7 .2 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 the target. 
 However, when faster ADCs become available, which  can accommodate higher analog input frequencies while providing adequate SNR and  SFDR, systems will be designed that sample the RF directly, as shown in Figure 25.44.  At this writing, ADC technology allows direct sampling systems with respectable perfor - mance to be designed for radars in the HF and VHF bands. Doubtless, future components  will extend this performance to higher RF frequencies. 
 Figure 25.40 shows an equivalent form for a CIC decimation filter, where the deci - mation occurs right after the integrator section and before the comb section. The delay  in the comb filter becomes a value Nt, where N is equal to D/R. This allows the comb  section to operate at the decimated sample rate, which makes it simpler to implement. 
 and might be difficult to achieve in practice.  Care must be exercised in the selection of the sidelobe level of a Taylor pattern. Large  antennas with narrow beamwidths can exhibit a severe degradation in gain because of  the large energy contained within the sidelobes as compared with that within the main beam. 
 For asingle stub, aslight correction tothelength isnecessary to allow forthe inductance ofthe crosspiece, but when the stubs become a solid tube, nolines offorce can link the narrow side, and the quarter- wave distance becomes exact. This also implies that the length ofthe narrow side ofthetube isnot critical. The two-wire transmission-line model explains how awaveguide can transmit allfrequencies higher (wavelengths shorter) than that forwhich thequarter-wave stubs were designed. 
 BIT ACCU 
 13.1] ELECTRICAL PROPERTIES OFCATHODE-RAY TUBES 477 approximately half ofthetotal voltage across agap intheAquadag ata point beyond the plates. The two parts are then spoken ofasthe “second anode” and “third anode.” Any variation ofthemean potential between either pair ofplates has amarked effect onthefocus; consequently ifgood focus isimportant itis necessary tousepush-pull deflection. IFurthermore, itisbest that the mean potentials oftheplates beclose tothat ofthesecond anode. 
 = velocity of poilit 1'. Froin this equation, the resolution in the .u dimension can be  writtcri  where T is the colierent integration tirnc equal to l/(A/,), and A0 is the angle through which the  body rotates during the time T. It does not take ti~uch of an angular rotation to produce good  resolution at microwave frequencies. 
 Increasing the radar energy in the direction of the jammer in the hope of increasing the  radar echo power above the jamming noise is called bumthrough. This may be accomplished  with reserve transmitter power or by dwelling longer in the direction of the jammer. Dwelling  longer on a target reduces the data rate, and thus can degrade the overall radar performance. 
 The interferometric baseline  increases with range and with platform velocity. It follows that for space-based radars,  ch18.indd   24 12/19/07   5:14:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 employing one or more sinusoidal modulations. There exist exact analyses of tri- angular, sawtooth, dual triangular, dual sawtooth, and combinations of some of these with noise,25 but heuristic techniques are usually a necessary starting point. 14.10 SINUSOIDALMODULATION Suppose one transmits an FM wave of the form Vs = U5 sin ((V + — sin comH \ ^m / where <om = modulation frequency O0 = carrier frequency Aft/a>m = modulation index An echo from a point target will have the form Ve = l/Jsin fnofr - T) + — sin o>w(f - T)] + <f>jIL <om JJ where c(> = arbitrary phase angle produced on reflection T = time delay of echo To introduce the effect of doppler we let T be time-dependent: T = T0 + 2vf/c, where v is the velocity of the echoing object and c the velocity of light. 
 pect angle is varied. For targets of other lengths with approximately the same shape factor, the response can be determined by sliding the curve along the \I2 line and making the first resonance coincide with the line at the !/2-wavelength point. Aircraft with their wing-fuselage cruciform shape will have an RCS that varies with the aspect angle but not greatly. 
  4RANSMITTER FOR  2ADAR AND #OMMUNICATION  )2$ 0ROJECT 2EPT   2ESULTS OF PERFORMANCE MEASUREMENTS    *ANUARY   $ * (OFT AND &UAT  !GI  h3OLID STATE TRANSMITTERS FOR MODERN RADAR APPLICATIONS v  #)% )NT 2ADAR  #ONF 2ECORD  "EIJING  .OVEMBER n    PP n  & ! 2AAB  0 !SBECK  3 #RIPPS  0 " +ENINGTON  : " 0OPOVIC  . 0OTHECARY  * & 3EVIC  AND  . / 3OKAL  h0OWER AMPLIFIERS AND TRANSMITTERS FOR 2& AND MICROWAVE v  )%%% 4RANS -ICROWAVE  4HEOR AND 4ECH  VOL   PP n  -ARCH   $ * .ETHERWAY AND #ARSON  # 4  h)MPEDANCE AND SCATTERING MATRICES OF A WIDEBAND (& PHASED  !RRAY v * %LECTRON %NG !UST   VOL   PP n    'UEST EDITORIAL AND INVITED PAPERS IN SPECIAL ISSUE ON SHORTWAVE BROADCASTING   )%%% 4RANS  "ROADCAST  VOL   *UNE   2 # *OHNSON AND ( *ASIK EDS    !NTENNA %NGINEERING (ANDBOOK   RD %D  .EW 9ORK -C'RAW 
 2.7 for each vaiue of 11. Such curves are  available, 11 but are not necessary since only Figs. 2.7 and 2.8 are needed. 
 87, 2003. 116. S. 
 Ifthe target isanairplane, for example, inspection ofFig. 3.8shows that even moderate yawing will introduce large fluctuations inreturned signal. The frequency spread sointroduced depends ontherate ofyaw and onthe ratio ofthetarget dimensions tothe wavelength, this ratio determining the number of pattern lobes per radian. 
 83-87, April, 1977.  66. Williams, P. 
 The NRL-ITS Radar Performance Model.  The NRL-ITS Radar Performance  Model developed by Lucas et al.152 provides a number of tools for radar per - formance estimation. It does not employ full 3D ray-tracing, such as the code  described by Jones and Stephenson,50 which can provide paths in three dimensions,  including delays and losses for both ordinary and extraordinary rays (see Section  20.4). 
 ASSP-23, no. 2, pp. 189–222,   April 1975. 
 The effect of the sidelobe clutter must often be considered in the design  of the signal processor of an airborne pulse-doppler radar.  The spectrum of the signal received by an airborne pulse-doppler radar might appear as  in Fig. 4.36. 
 Wave Shape ........ Direct-driven Generators. Motor-alternator Sets Voltage Regulators. 
 KM SWATH   INCIDENCE 
     2ADARS WITH ROTATING ANTENNAS THAT  MEASURE PRECIPITATION RATE  DOPPLER VELOCITY  AND TURBULENCE -EASURES TOTAL RAINFALL  AND PROVIDES TORNADO WARNINGS  4ERMINAL  $OPPLER  7EATHER  2ADARS  4$72    2ADARS WITH ROTATING ANTENNAS  DESIGNED TO DETECT SEVERE WIND SHEAR IN AIRCRAFT APPROACH AND DEPARTURE PATHS CLOSE TO AIRPORTS  !IRPORT 3URVEILLANCE 2ADARS  2ADARS WITH ROTATING ANTENNAS DESIGNED FOR AIR  TRAFFIC CONTROL FUNCTIONS IN THE TERMINAL AREA BUT WITH A SECONDARY FUNCTION OF DETECTING AND MONITORING SEVERE WEATHER AND WIND SHEAR IN AIRCRAFT APPROACH AND DEPARTURE PATHS  0HASED !RRAY 2ADARS  2ADARS WITH FIXED ELECTRONICALLY SCANNED ANTENNAS DESIGNED  FOR MANY FUNCTIONS SUCH AS MISSILE DETECTION AND AIR TRAFFIC CONTROL  AND USED CON 
 The beams may be selected through a switching matrix requiring M-I single-pole-double-throw (SPDT) switches to select one out of M beams. The beams are stationary in space and overlap at about the 4 dB points. This is in contrast to the previously discussed methods of scanning, where the beam can be steered accurately to any position. 
 14, pp. 29-32,  April, 1971.  42. 
 ,/" - &OUR OF THE MORE SIGNIFICANT FACTORS THAT AFFECT THE DESIGN OF METEOROLOGICAL RADARS ARE ATTENUATION  RANGE AMBIGUITIES  VELOCITY AMBIGUITIES  AND GROUND OR SEA CLUTTER 4HE COMBINATION OF THESE FACTORS  ALONG WITH THE NEED TO OBTAIN ADEQUATE SPATIAL RESOLU 
 Barker, “Group synchronization of binary digital systems,” in Communication Theory ,   W. Jackson (ed.), New York: Academic Press, 1953, pp. 273–287. 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 In some cases, leading- or lagging-edge range tracking is desired. This has been  accomplished in some applications by simply adding a bias to move the error-sensing  gates either to lead or lag the center of the target. 
  AND ITS FOLLOWERS HAVE HAD ONBOARD DATA RECORDING CAPABILITY %23 
 in some respects, a cross between the constrained feed and the space feed.  Constrained feed. Figure 8.21 shows a two-dimensional-scanning array which is sometimes  known as a parallel-series feed. 
 W. 1'. lloopcr. 
 TION THAT THE RECEIVER BANDWIDTH IS MATCHED TO THE DURATION OF THE TRANSMITTED PULSE )N A PULSE COMPRESSION SYSTEM  THE RECEIVER BANDWIDTH IS WIDER BY THE TIME 
 10.24  Polyphase Code s  ..............................................  10.25  10.7 Time-Frequency-Coded Waveforms  ......................  10.26  10.8 Weighting and Equal ization  .................................... 
 ORBIT MASS OF THE SPACECRAFT WILL BE  ^ KG  OF WHICH  THE 3!2 PAYLOAD INCLUDING THE ANTENNA  CLAIMS  ^ KG /NBOARD DATA STORAGE CAPAC 
 48, pp. 898-903, May, 1960.  47. 
 21. P. D. 
 Pulse Radar Equation. Equation (2.6) does not specify the nature of the transmitted signal; it can be CW (continuous-wave), amplitude- or frequency-modulated, or pulsed. It is advantageous to modify this equation for the specific case of pulse radars and in so doing to remove the "bandwidth" difficulty encountered in using Eq. 
 Blacksmith, P., Jr., R. E. Hiatt, and R. 
 The wave will either strike the Earth and undergo surface reflection, or enter  a region of standard refraction and be refracted back upward, only to reenter the area of  refractivity gradient that causes downward refraction. This refractive condition is called  trapping because the wave is confined to a narrow region of the troposphere. The common  term for this confinement region is a tropospheric duct  or a tropospheric waveguide . 
 By using the terminal-fall speed data of Gunn and Kinzer,52 the rainfall rate can also be obtained and Z directly related to R. Clearly, a single-wavelength, single-polarization radar can measure only a sin- gle parameter Z and must assume Rayleigh scattering. Since the rainfall rate de- pends upon two parameters, N0 and A, it is not surprising that Eq. 
 2. Aeff = effective area contributing to multiple internal reflections. 3.A = actual area of the plate. 
 Since neither ofthese methods can begenerally applied, itwill sometimes benecessary tooperate the magnetron heater ondirect current. Heater hum modulation should eventually bemade amatter oftube-manufacturing specification. The useofasupersonic delay line necessitates aconstancy ofPRF to &ofapulse width. 
 During the run time  € Δt=2Rc0 for the signal to the target and back, the transmitting frequency is altered corr e- sponding to  € Δt:  € fT=f0+Δf⋅t+Δt T (7.7)  . Radar System Engineering  Chapter 7 – CW and FM -CW Radar  46     The mixing of the received signal with the current transmitting signal takes place in the Radar  receiver.  From t his the result is, among other things, the difference frequency  € fB, also known  as the “beat frequency”:   € fB=(f0+Δf⋅t+Δt T)−(f0+Δf⋅t T)=ΔfΔt T (7.8)  The range R follows from this:  € R=c0⋅fB 2Δf⋅T (7.9)  The beat frequency is proportional to th e target range R. 
 If f(t) with the form given by Eq. (21.22) is used in Eq. (21.20), one obtains for the ambiguity function the ex- pression X = fg\* - —1 **[> - —I *'WWc - 2R>/C) dt (21.23)J L cJL cJ Let J(t) consist of a sequence of transmissions. 
 J. Zolper, “Scanning the special issue, special issue on wide bandgap semiconductor devices,”  Proceedings of the IEEE , vol. 90, no. 
 O. Pearson, and E. Shamash, “Principles of Modern radar,” Evolving Technology  Institute Short Course Notes, June 1988. 
 VARYING POLARIZATION MISMATCH AT THE RECEIVING ANTENNA &IGURE  GIVES THE VERTICAL 
 Spaulding, D. Horton, and P. Huong, “Wind Aspect Factor in Sea Clutter Modeling,” presented  at 2005 IEEE International Radar Conference, 2005. 
 I)., S. M. Slierman. 
 The "boundary " RF between Fresnel and Fraunhofer regions is usually taken to be either  RF = DZ/A or the distance RF = 2D2/A, where D is the size of the aperture and ,I is the  waveletigth, D and A being measured in the same units. At a distance given by D2/A, the gain of  a ~rriifortnly illuminated antenna is 0.94 that of the Fraunhofer gain at infinity. At a distance of  2D2/?,, the gain is 0.99 that at infinity. 
 4, pp. 166–173, August 2002. 127. 
 FINDING RADARS  IT IS THE PROP 
 B., and A. B. Rohwer: Structural Design Improvements of ESSCO Radomes and  Antennas, IEEE 1977 Meclranical Engi11eering in Radar Symposium, Nov. 
 Although the limiters cause partial or complete suppression of some desired targets in  the clutter areas, no targets are suppressed that could otherwise have been detected in  the presence of clutter residue at the system output if the limiters had not been used. As a specific example, consider a system with a pulse-compression ratio of about  30 dB and system instability noise approximately 28 dB below the carrier power.  Assume that the MTI canceler improvement factor is 30 dB, limited by clutter spec - tral spread. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 composed of the radar measurement accuracies in range, azimuth, elevation, and dop - pler. 
 IZATION DRAMATICALLY WITH CONSEQUENT INCREASES IN RADIOWAVE ABSORPTION 7ITHIN AN HOUR AND FOR A DAY OR SO AFTER  FLARE 
 I\ "typical" IF amplifier for an air-surveillance radar might have a center frequency of 30  or 60 MHz and a bandwidth of the order of one megahertz. The IF amplifier should be  designed as a matclted filter; i.e., its frequency-response function H(f) should maximize the  peak-signal-to-mean-noise-power ratio at the output. This occurs when the magnitude of the  frequency-response function [ H(f) I is equal to the magnitude of the echo signal spectrum  I S(l) [. 
 Forrest, Guest editor, special issue on phased arrays, Proc. IEE  (London ), vol. 127, pt. 
 IEEE, vol. 53, pp. 317-318, March, 1965  22. 
 4.14b to d were derived from the low-pass filter characteristic of  Fig. 4.14a. This type of filter characteristic may be obtained with a single delay line in cascade  with a double delay line as shown in Fig. 
 For targets of other lengths with approximately the same shape factor,  the response can be determined by sliding the curve along the λ/2 line and making the  first resonance coincide with the line at the 1/2 wavelength point. As has been men - tioned, Faraday rotation results in varying incident polarization, so over time a target  will experience both favorable and mismatched polarization, with resultant fading of  the scattered signal. Of course, additional fading of the scattered signal occurs due to  time-varying polarization mismatch at the receiving antenna. 
 REFERENCED EQUATIONS INTO INCLUDED 
 M;ty, 1970.  XI. Morg;~r~. 
 HH HH     WHERE G AND G ARE THE IMPEDANCES OF MEDIUM  AND   RESPECTIVELY 4HE REFLECTION COEFFICIENT HAS A POSITIVE VALUE WHEN  G   G  SUCH AS WHERE AN  AIR 
 AIR  AND AIR 
 This is the probability of associating ( u, v) with  H2 when H1 is the true hypothesis. PTB is related to SNR, F, and the auxiliary gain   w = GA/Gt normalized to the gain Gt of the main beam. To complete the list of param - eters needed to describe the SLB performance, the last figure to consider is the detec - tion loss L on the main-beam target. 
 Kaiser. J. A,: Spiral Antennas Applied to Scanning Arrays, Elecrronic Scanning S~~nrposiurtt, Apt. 
 QUENCY AND INCREASED POWER ARE TO DISTINGUISH BETWEEN RAIN AND SNOW AND TO INCREASE SENSITIVITY TO RAIN RATES AS LOW AS  MMHR , 
  MI SSION DID NOT VARY  ITS REPEAT PERIOD 4HE CONSEQUENCE OF THESE ORBIT PROPERTIES IS THAT THE RESULTING DATA ARE NOT WELL SUITED TO MEASURING THE ANNUAL RATE OF SEA 
 Sensors 2019 ,19, 2605 between objects imaged at different times. When every small intensity change creates a colored pixel, it becomes more difﬁcult for operators and/or algorithms to detect meaningful changes and identify corresponding objects of interest. Figure 1. 
 Part of the  additional clutter spectral components comes from the sharp discontinuity in the  envelope of returns as the clutter reaches the limit level.33 A time-domain example  of this phenomenon is shown in Figure 2.63 for a radar with N = 16.4 hits per beam - width. On the left is a point target that does not exceed the limit level; on the right  is a point target that exceeds the limit level by 20 dB. Note that, for this example,  I degrades by 12.8 dB for the dual canceler and by 26.5 dB for the triple canceler. 
 A.J..A.C.Layton, andP.K.Schefel: AQuasiLinearFM/CW LaserRadar.IEEE1975 IlfIematicJ/lal RadarCOIl!t'I"I.'/lce. Apr.21-23.1975.Arlington. VA,pp.128-131. 
 Since the inside face of the PPI is coated withphosphorescent material, a small bright spot is formed at the center of thePPI.If the electron beam is rapidly and repeatedly deﬂected radially from the center,abrightlinecalledaTRACEisformedonthePPI.Shouldtheﬂowofelectrons be stopped, this trace will continue to glow for a short periodfollowing the stoppage of the electron beam because of the phosphorescentcoating. The slow decay of the brightness is known as PERSISTENCE; theslower the decay the higher the persistence. At the instant the modulator triggers the transmitter, it sends a TIMING TRIGGER signal to the indicator. 
 A single waveform may be used to track  stationary, endo- and exoclutter moving targets, and missiles or bullets. Each class of  return, based on its range and doppler location, is separately tracked and geolocated.94 There are several common types of geolocation; many of them are based on using  either DTED or cartographic data. One method using cartographic data is shown  FIGURE 5.37  Multiregion GMT thresholding8 (Courtesy SciTech Publishing ) ch05.indd   40 12/17/07   1:27:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The basic diagram is shown in Fig. 14.9. The simple appearance of the figure is deceptive. 
 I3ut consider tlie two signals at B and C, representing target echoes of equal atnplitudc. 'I'lic  noise voltage accompanying the signal at B is large enough so that the combination of signal  plus noise exceeds the tlireshold. At C the noise is not as large and the resultant signal plus  rioise does not cross the tlireshold. 
 ITY COMPARED WITH THAT OF STRINGS AND PLASTIC FOAM COLUMNS (OWEVER  BECAUSE THE TOP OF THE PYLON IS SMALL  THE ROTATION MECHANISM NEEDED TO VARY THE ASPECT ANGLE OF THE TARGET MUST BE EMBEDDED IN THE TARGET ITSELF 4HIS USUALLY  DESTROYS THE OPERATIONAL  VALUE OF THE TARGET -OST OF THE ROTATORS FOR THESE PYLONS ARE DUAL 
 McC.: A Radar Detection Philosophy, IRE Trans., vol. IT-2, pp. 204-221, September,  1956. 
 This control also allowed the hole to be widened when homing onto a target. This meant that even targets at short range could bedisplayed near the edge of the PPI, allowing better estimates of their bearings. Once a homing run was completed, the 10 mile zero would be reset to the centre. 
 47. R. W. 
 ENCES ARE EXPECTED TO COME !S AN EXAMPLE  A PROBABLE REGION WITH INTERFERENCES IS THE HORIZON OR PART OF IT BECAUSE JAMMERS ARE MOSTLY GROUND 
   4AYLOR N     
 UP AIDS COMPARISON WITH PAPER CHARTS .OWADAYS  #OURSE 
 Such antennas therefore permit the useofmuch lower power toachieve agiven result than would berequired with omnidirectional antennas. Highly directional antennas can always beused for transmkaion. 714 RADAR RELAY [SEC. 
 It has a variety of modes, from ScanSAR (15-m resolution over 100-km  swaths) to SpotSAR (1-m resolution over a 5-km by 10-km image frame). Its strip  mapping mode is baselined at 3-m resolution across 30-km swaths. The array is  partitioned in the along-track direction, which can be exercised in a two-aperture  along-track interferometric mode for GMTI experiments, among other applications. 
 11”1, the impedance atthe input end ofanopen quarter-wave section (in this case across the gap inthe line) is zero. Power flows across without loss orsparking. Closer analysis shows that the open end ofthe quarter- wave section ontheouter conductor isnotaninfinite impedance, because there issome radiation, producing afinite radiation resistance. 
 The trans- mitters are power amplifiers (traveling-wave tubes, klystrons, twystrons, crossed-field amplifiers, solid-state amplifiers, etc.) rather than oscillators (magnetron, etc.). It is this double use of the stalo that introduces a dependence on range of the clutter and exaggerates the effect of certain unintentional phase- modulation components by 6 dB, the critical frequencies being those which change phase by odd multiples of 180° during the time period between transmis- sion and reception of the clutter echo from a specified range. At these critical frequencies, a maximum positive phase deviation on transmission changes to a maximum negative deviation at the time of reception, doubling the undesired phase modulation of the echo at IF. 
 (21.24) results in T/2 ^ = eia[(2R/c)2 - (2R1Ic]2] f ^-ia[(4R/c)/-(4J?7c)/]rfr (21.35) -T/2 . 4> = e<«[(2*/02 - (2R'/c)2] T sin {gT[(2fl/c) - (2R'lc)]} oLT[(2R/c - 2R9Ic)] U ' Equation (21.36) gives the range resolution factor of the ambiguity function for a transmitted waveform of the type expressed by Eq. (21.34). 
 Displacement Estimation Preliminary displacements are estimated by a linear model that is robust and commonly used [ 36]. Meanwhile, the residual topography is also removed. Then, atmospheric phase was removed by an atmospheric ﬁltering. 
 The advantages of the envelope detector, illustrated in Figure 6.11, whose central ele- ment can, for example, exhibit a linear, a square or a logarithmic characteristic, lie in it’ s sim- ple feasibility.     Figure 6.11  Receiver stages of a Radar with envelope detector.     By these simple detectors only the amplitude is preserved , the phase information is destroyed. 
 Fachofthe54rowscontains itsowntransceiver withtwcnty-two 50-Wmodules alongwithphaseshifter. low-noise amplifier. outputfilter.circulator. 
 G., et al.: The Study of Venus by Means of the Bistatic Radar Method, Radio Eng. Electron. Phys. 
 Sources of interference within the radar coverage  (e.g., on an airborne platform) can potentially screen the platform in range and impair  the detection of other targets with similar azimuth but possibly at different ranges.   ch24.indd   52 12/19/07   6:01:13 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 DEPENDENT TRANSLATION ERRORS 2ANGE OSCILLATOR FREQUENCY$ATA TAKEOFF ZERO SETTING2ANGE RESOLVER ERROR)NTERNAL JITTER$ATA GEAR NONLINEARITY AND BACKLASH$ATA TAKEOFF NONLINEARITY AND GRANULARITY2ANGE OSCILLATOR INSTABILITY 4ARGET 
 BAND RADIO WAVES  0ART )) v '%#  %LECTRONICS  ,TD  3TANMORE  %NGLAND  -EMORANDUM 3,-  *ULY    ! 2 $OMVILLE  v4HE BISTATIC REFLECTION FROM LAND AND SEA OF 8 
 FREE REGION OF DOPPLER FREQUENCY WHEN A PULSE DOPPLER WAVEFORM IS USED 4HESE TARGETS NOW HAVE TO COMPETE ONLY WITH SYSTEM NOISE 4HIS NOISE CAN BE BOTH ADDITIVE AND MULTIPLICATIVE !DDITIVE NOISE TENDS TO MASK MULTIPLICATIVE NOISE IN LOW 
 The work in [ 17] presents a new method for refocusing moving ships in SAR images. Ship detection is widely required for both civilian and military surveillance; however, SAR images derived by standard focusing suﬀer from strong blurring in presence of moving ships. Therefore, a further processing step is needed, which performs reliable motion compensation and refocusing. 
 It is possible to  scan the stepped reflector to slightly wider angles than a simple paraboloid, but not as wide as  with some other scanning techniques. Disadvantages of this reflector are'the scattered radia­ tion from the stepped portions and the narrow bandwidth.  If only a portion of the spherical reflector is illuminated at any one time, much wider scan  angles are possible than if the entire aperture were illuminated. 
 Eventually Lord Swinton, who was in 1935  Secretary of State for Air, appointed a committee con-  sisting of Mr H. T. (now Sir Henry) Tizard and Pro-  fessor A. 
 TO 
 This is a lossless network which  utilires 3-dB directional couplers, or hybrid junctions, along with fixed phased shifters, to forni  N contiguous beanis from an N-element array, where N is an integer that is expressed as some  power of 2, that is, N = 2P. The 3-dB directional coupler is a four-port junction which has the  property that a signal fed into one port will divide equally (in power) between the other two  ports and no power will appear in the fourth port. A 90" phase difference is introduced  between the two equally divided signals. 
 176. A. Pazmany, R. 
 NAS AT SEPARATE LOCATIONS  ONE ANTENNA FOR TRANSMISSION AND MULTIPLE ANTENNASEACH AT A DIFFERENT LOCATIONFOR RECEPTION  OR VICE VERSA !GAIN  TRANSMITTERS OR RECEIVERS ARE USUALLY SITED WITH THE ANTENNAS 4ARGET DETECTION IS DONE BISTATICALLY  WITH EACH TRANSMIT 
 In practice the operator would adjust the gain and brightness to achievean acceptably low false alarm rate at long range in noise. At shorter range, the clutter levels would usually be very high. The sea return discriminator described in chapter 3(section 3.3.2) could be used to reduce the clutter intensity and prevent theAirborne Maritime Surveillance Radar, Volume 1 7-9. 
 Solid ', - - - curve represents echo pulse un-  corrupted by noise. Dashed  + curve represents the effort of  = tr noise.  EXTKACTION OFINH)RMATION ANDWAVEFORM DESIGN401 mightalsobemeasured, butitsprecisevalueisusuallynotimportant exceptinsofarasit influences thesignal-to-noise ratio. 
 A ES-7, pp. 1 123-1 130, November, 197 1. .j  50. 
 Therefore, since the early 1960s there has been a tendency for radar systems to employ increased duty cycle, by the use of techniques such as pulse compression, to achieve higher average power without a further increase in peak power. Although in many cases a single RF tube can produce so much average power that even pure-copper waveguide requires water cooling, the limit in system average power may still be the RF tube. Furthermore, asking for the ultimate power capability in one RF tube has a high risk of leading to an unsuccessful development program or to an unreliable tube even if the development is "successful." From a reliability standpoint as well, multiple smaller tubes are often preferable to a single very large tube. 
 29-32,  April, 1971.  42. Acker, A.: Selecting Tubes for Airborne Radars, Microwai,e Syscem News, vol. 
 At greater angles the element pattern has values that are greater than those given by Vcos 6 and that are a function of the total number of elements.42 Scanned Linear Arrays. The pattern of the array may be steered to an angle G0 by applying linearly progressive phase increments from element to element so that the phase between adjacent elements differs by 2ir(s/X) sin G0. Equation (7.2) is then modified, giving the normalized array factor of a uniformly illuminated array as sin A%(s/X)(sin G - sin G0) a N sin ir(j/X)(sin G - sin G0) and the pattern is sin NTT(S/K) (sin G - sin G0) EW = Ee(0) . 
 The number of terms N required to compute the value of the bracketed term in Eq. (11.6) to six decimal places for ka < 100 is approximately N = 8.53 + l.2l(ka) - 0.001(M2 (11.8) The constants in Eq. (11.8) are slightly different for ka > 100 and are lower in value for fewer decimal places in the required accuracy. 
 FALSE 
 The method of solution is known as  the method of moments  (MOM) ,25 which reduces the integral equations to a collection  of homogeneous linear equations that may be solved by matrix techniques. Once the boundary conditions have been specified, the surface S is split into a col - lection of discrete patches, as suggested in Figure 14.15. The patches must be small  enough (typically less than l/5) that the unknown currents and charges over each patch  are constant or at least can be described by simple functions. 
 Learning of CNNs 2.2.1. Environment The networks are implemented in Pytorch 0.3.0. All layers were designed to match the size of images. 
 CONTROLLED TUBES KNOWN AS THE #ONSTANT %FFICIENCY !MPLIFIER  OR THE )NDUCTIVE 
 Radar System Engineeri ng Chapter 8 – Pulse Radar  52     8.4 Coherent Pulse Radar   Coherent pulse Radar is in the position to deliver information regarding the range as well as  Doppler information, i.e. the velocity and/or speed of an object.  H ere a coherent oscillator  (COHO) is introduced on the transmission side, which also delivers the phase reference for the receiving signal. 
 A. Soofi, and S. M. 
 (b) Phase shifters  Rodia ting  elements  Figure 8.24 Example of a pillbox antenna (shown in (a)) used as a kcd for an array (b). (-~lier Rirnrdi.1t.i)  \, 8.7 SIMULTANEOUS MULTIPLE BEAMS FROM ARRAY ANTENNAS  \...  One of the properties of the phased array is the ability to generate multiple independent beam:. 
 S. Aks, D. D. 
 Thepeakmightbenarrowed, butinordertoconserve thevolume underitssurface. thefunction mustberaisedelsewhere. Ifthepeakismadetoonarrow, the requirement foraconstant volume mightcausepeakstoformatregionsoftheambiguity diagram otherthantheoriginandgiverisetoambiguities. 
 S. R .. and M. 
  PROJECT v  $IG )'!233   )%%%  #( 
 This is analogous to the output of a beam­ forming matrix, as in Sec. 8.7. The number of filters depends on the antenna beamwidth and . 
 For operating voltages of 7–10 volts, a normalized power output density of  0.6–0.8 W/mm should be expected; for more advanced GaAs PHEMT structures oper - ating at 11–28 volts, one can expect to deliver 1.1–2.0 W/mm of normalized power  output density. Thus, to achieve a power level of 20 watts at 10 GHz, when operating  from 15 volts, approximately 80 gate fingers must somehow be combined in parallel to  FIGURE 11.9  Cross section of a 0.25 µm double gate–recessed GaAs  PHEMT transistor, showing gate, drain, and source metals ( Photograph  courtesy  of Raytheon Company ) ch11.indd   14 12/17/07   2:25:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Each dimple is aligned with the  openings of the grid so that beam lets are formed within each grid opening. The beam intercep­ tion on the control grid or practical nonintercepting gridded guns might be less than a few  hundredths of one percent of beam current.8 The shadow grid can also be used in the  traveling-wave tube.  Bandwidth. 
 Itsprincipal drawback isitsrelative complexity, but much ofthecomplication inFig. 17.14 arises from extreme precautions against interference and from the necessity ofoperating aservomechanism. Were fixed-coil PPI’s used, orwere itpossible tooperate aservomecha- nism satisfactorily from d-csignals, theequipment would beconsiderably simplified. 
 Each analog beamformer is designed to produce one of the N offset  beams in a beam cluster. Another way to generate multiple simultaneous receive beams  is to use digital beamforming (DBF), which is discussed in more detail in the next sec - tion. DBF is usually preferred when a large number of beams are to be formed. 
   %23 
 BAND RADAR IN THE WORLD )T CONSISTS OF THOUSANDS OF ELEMENTS DRIVEN BY TRANSMITRECEIVE 42  MODULES )N THE 8 
 A.: The Interpretation of Amplitude and Phase Distortion in Terms of Paired Echoes, Proc. IRE, vol. 27, pp. 
 TO 
 ART BACK IN  FOR 3!2 DATA  0ENETRATION DEPTHS PROVED TO BE APPROXI 
 ANTENNA ARCHITECTURE  3YSTEM SENSITIVITY ACCOMMODATES  R   IN THE RANGE   n D" TO n D" 4HE ANTENNA IS A  
 B. Leeson and G. F. 
 The reader is referred to the review paper by Rottger and Larsen82 for a thor- ough treatment of wind-profiler technology. Synthetic Aperture Radar and Pulse Compression. Metcalf and Holm83 and Atlas and Moore84 have considered the use of synthetic aperture radar (SAR) in order to obtain high-resolution measurements from mobile airborne or space- borne platforms. 
 3, pp. 364-380, 1952; also reprinted in Proc. Symposium on Communication Theory and  Antenna Design, AFCRC Tech. 
 3.7 FILTERING Filtering of the Entire Radar System. The filter provides the principal means by which the receiver discriminates between desired echoes and interference of many types. It may approximate either of two forms: a matched filter, which is a passive network whose frequency response is the complex conjugate of the transmitted spectrum, or a correlation mixer, an active device which compares the received signals with a delayed replica of the transmitted signal. 
 R. H. Abrams, Jr., “The microwave power module: A ‘supercomponent” for radar transmitters,”  Record of the 1994 IEEE National Radar Conf ., Atlanta, GA, pp. 
 A number of techniques have been studied for providing data regarding both translation and rotation of moving objects. An example of such work is that of B. Steinberg.18 Three-Dimensional Spectrum. 
 Temporal coverage is illustrated in Fig. 22.11, which shows the maxi- mum time for viewing ground objects from a space vehicle if the objects are tracked.28 It can be seen that a ground object can be observed for more than 7000 s when the orbital altitude is 6000 nmi. 2. 
 M 3POT3!2 RESOLUTION CONSTRAINS THE DESIGN  ONE CONSEQUENCE OF WHICH IS THE SYMMETRICAL BODY 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°Óx TRACK HISTORY IE  THE LAST  N DETECTIONS  4RACKS AND DETECTIONS CAN BE ACCESSED IN VARI 
 Kato, Y . Takizawa, S. Sasaki, and the SELENE Project Team, “SELENE, the Japanese lunar  orbiting satellite mission: present status and science goals,” in Proceedings, Lunar and Planetary  Science XXXVII , Houston, TX, pp. 
 There are several methods of averaging or “stacking”  the data; either a complete set of samples can be gathered and stored and further sets  added to the stored data set, or alternatively, the sampling interval is held constant for a  predetermined time to accumulate and average a given number of individual samples.  The first method needs a digital store but has the advantage that each waveform set  suffers little distortion if the radar is moving over the ground. The second method does not need a digital store and a simple low-pass analogue  filter can be used. 
 NATED BY A PLANE WAVE IS '   S 4HE DIFFRACTION COEFFICIENTS ARE   8NN NNIS 
 Image Process. 1999 ,8, 1823–1831. [ CrossRef ][PubMed ] 5. 
 Veryfewmicrowave radarshave thecapahilit~of penetrating thediffraction regiontoanygreatextentbecause ofthesevere losses. Theeffectoftheroundearthonradarcoverage canbepredicted byanalytical meansfor theidealized caseofa"smooth" earthofknown. uniform properties. 
 BAND RADAR  AT  GRAZING ANGLE AND WIND ABOUT  KT  0OINTS EXPERIMENTAL DATA FROM  0OLRAD EXPERIMENT  DASHED LINE PURE 30- "RAGG  DASHED 
 Sd., vol. 39, pp. 258-279, 1982. 
 Many of the guidelines for paraboloids except space taper can be carried over to parabolic cylinders. Since the feed energy diverges on a cylinder instead of a sphere, the power density falls off as p rather than p2. Therefore, the space taper of Eq. 
 Since returns from land clutter scatterers usually are spatially fixed and, therefore,  appear at the same range and bearing from scan to scan, it has long been recognized  that a suitable memory circuit could be used to store the clutter residues and remove  them from the output residue on subsequent scans by either subtraction or gain nor - malization. This was the basic principle of the so-called area MTI, and many attempts  have been made to implement an effective version of this circuit over an extended span  of time. The main hindrance to its success has been the lack of appropriate memory  technology, since the storage tube (long the only viable candidate) lacks in resolution,  registration accuracy, simultaneous read-and-write capability, and stability. 
 Because Z values of interest can range  over several orders of magnitude, a logarithmic scale is often used. Thus,  dBZ = C + Pr (dBm) + 20 log r (km) (19.14) ch19.indd   5 12/20/07   5:37:49 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 The frequency of tlie received echo signal will  clcl>cti(l oti tlic clcvi~~ioti ;iriglc of tllc t:~rget. A batik of corltigitoi~s receivers. each tuned to :I  diflkrcnt I'sequcncy. 
 This is a relatively popular radar band for military  applications. It is widely used in military airborne radars for performing the roles of  interceptor, fighter, and attack (of ground targets), as discussed in Chapter 5. It is also  popular for imaging radars based on SAR and ISAR. 
 You can  thus picture the aerial system as something like the  headlamp of a car, or a highly directional searchlight,  broadcasting a pencil-like beam which scans the skies.  With normal frequencies there are two ways of making  an aerial directional. We can build it up on the search-  light principle, with reflectors and ‘directors,’ which  are really the electrical counterparts of the similar optical  systems. 
 R. J. Keeler, “Weather radars of the 21st century: a technology perspective,” in 28th Conf. 
 1947.  40. Seckelmann, R.: Phase-Shift Characteristics of Helical Phase Shifters, I £EE Trans, vol. 
 QUALITY DIELECTRIC SUB 
 DIMENSIONAL #ARTESIAN COOR 
 FORM  EACH ELEMENT SEES AN APPARENT CLUTTER VELOCITY DUE TO ITS ROTATIONAL MOTION  AS ILLUSTRATED IN &IGURE  B 4HE APPARENT VELOCITY VARIES LINEARLY ALONG THE APERTURE  (ENCE  THE TWO 
 In the extreme, the peak-io-peak trac ing error would  not exceed 0.7 to 0.8 beamwidth and typically the rms error would be about 0.3 beamwidth.  These relatively simple methods, combined with heavy smoothing of the error signal, can  allow meaningful, but not necessarily accurate, tracking at low angles.  The surface-reflected signal travels a longer path than the direct signal so that it may be  possible in some cases to separate the two in time (range). 
 AP-23, pp. 269-271, Marcll. 1975. 
 Frequency agility,asdescribed hereforthereduction ofglint,appliestothemonopulse trackingradar.Italsoreducestheglintinaconicalscanorasequentiai-Iobing radar,butthe. 172 INTRODIJCTION TO KADAK SYSTEMS  changing frequency can result in amplitllde fluctilations wl~iclt can affect the angle tracking  accilracy if the spectrum of the fluctuations at the conical scan or the lobing freqt~zncies is  increased. Thits, frequency agility might cause an increase in the angle error dile to amplitutie  llitcti~ations in these systems while decreasing the error due to glint. 
 Unlike the silicon power transistors, the GaAs FET and its associated  FIGURE 11.4  Typical transistor current-voltage continuum (I-V plane)  showing key FET dc performance limits with optimum load line for   power output shown. Higher power output is achieved when the maxi - mum channel current ( IMAX) and the breakdown voltage ( VDGB) are both  increased. Optimum amplifier design places the load line as indicated. 
 373-385.  7. Cutrona L. 
 70.4 NONLlNEARFM The nonlinear-FM waveform has attained little acceptance although it has several distinct advantages. The nonlinear-FM waveform requires no time or frequency weighting for range sidelobe suppression since the FM modulation of the waveform is designed to provide the desired amplitude spectrum. Matched-filter reception and low sidelobes become compatible in this design. 
 TO 
 GIT clutter re ﬂectivity for SS 1, 2, 3 and 4, H polarisation, looking up-wind; solid line: S-band; dashed line: X-band. Table 7.6. Douglas sea states. 
 Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). 25. 
 The ISAR complex image as ISAR amplitude and ISAR phase is extracted from the range compressed signal by applying azimuth compression with inverse Fourier transform (11) realized by inverse fast Fourier transform. The ISAR image amplitude and the ISAR image phase, the complex image with (−15) dB signal to noise ratio, just after azimuth compression of the range compressed ISAR signal, are presented in Figure 8a,b, respectively. The asteroid’s image is obscured by noise. 
 Olson, “Recognizing low-altitude wind shear hazards from doppler weather  radar: an artificial intelligence approach,” J. Atmos. Ocean. 
 SANDWICHES 4HIS CONFIGURATION IS USED WHEN THE ORDINARY ! 
 (8.16),  we have ·  2rr(d/).) sin 00 + 2rrm = 2nl/}.. (8.17a)  or . ml I  sm 00 = --J" + d (8.17b)  When the beam points broadside, (00 = 0), Eq. 
 The Potential of Low-Frequency SAR Systems for Mapping Ionospheric TEC Distributions. IEEE Geosci. Remote Sens. 
 ERENCE  ANALOG TO DIGITAL CONVERSION !$   INPUT 
 K. Barton, Modern Radar System Analysis and Modeling , Canton, MA: Artech House Inc,  2005, Chap. 5, p. 
 14. P. Swerling, “The ‘double threshold’ method of detection,” Project Rand Res. 
 The gain of a transistor is only of tlic  order of 10 dB, so tliat several stages of amplification are necessary to achieve a reasonable  total gain. An L-band module using eight transistors (four paralleled in the final stage, two  paralleled irl tlie penultimate stage, and two series driver stages) might have a peak power  greater than 200 W, 0.1 duty cycle, 200 MHz bandwidth, a gain of 30 dB, and an efficiency  better than 30 per~ent.~' (Wlien examining the claims of power from solid-state devices, it  stiould be kept in mind that the greater the junction temperature the less the life of the device.  Since long life is a featured characteristic of such power sources, they should be operaied  conscrvat ively.)  The power output of a microwave transistor theoretically decreases inversely as the  square of the frequency, or 6 dB per octave.29 For this reason the silicon bipolar transistor is  ilnattractive for radar application at S band or above, especially when appreciable power is  desired. 
 It also  reduces the likelihood of mutual interference between equipments, and makes more difficult  Frequency GHz  30 300 3,000 3 x 104 3 lo5 3 ,. lo6  1 I 1  I+- Mill~meter - -+-Submillimeler -+/+--Far infrared. +/+ -- Infrared - +I I.+  resonance  KO 94 GHz  band w~ndow COP loser  1 t t 1 I I I  1.0 cm 1 0 mm 01 mm 10 pm 10pm 0 1 pm  Wovelength  Figure 14.14 The electromagnetic spectrum of frequencies above the microwave region. 
 MATCHING PROBLEMS NORMALLY ASSOCIATED WITH VERY HIGH POWER TRANSISTORS 4HE 2& INPUT DRIVE TO THE MODULE WAS  7 PEAK AND WAS USED TO DRIVE TWO DEVICES ! COMBINED POWER LEVEL OF GREATER THAN  7  WAS SPLIT EIGHT WA YS TO DRIVE THE EIGHT  IDENTICAL OUTPUT STAGES ,OSSES IN THE OUTPUT CIRCULATOR  FINAL POWER COMBINING  AND THE FAULT DETECTION CIRCUITRY REDUCED THE COMBINED POWER LEVEL TO  7 /UTPUT MODULES WERE LIQUID 
 281, pp. 17-21, 1987. 85. 
 50.Davies,D.E.N.,andH.Makridis: Two-Frequency Secondary RadarIncorporating PassiveTrans­ ponders, Electronics Letters,vol.9,no.25,pp.592-593, Dec.13,1973. 51.Lewis,R.M.:Physical OpticsInverseDiffraction, IEEETrans.,vol.AP-17,pp.308-314, May,1969. 52.Kennaugh, E.M.,andD.L.Moffatt: Transient andImpulse Response Approximations, Proc.IEEE, vol.53,pp.893-901, August,1965. 
 DEVELOPED BISTATIC WIND MEASUREMENT PROTOTYPE  SYSTEM ! MODIFIED #0 
 Theresultisanerrorinthemeasurement ofelevation. The surface-reflected signalmaybethought ofasoriginating fromtheimageofthetargetmirrored bytheearth'ssurface.Thus,theeffectontracking issimilartothetwo-target modelusedto describe glint,asdiscussed previously. Thesurface-reflected signalissometimes calleda n111[tipath signal. 
 SBR-related patent applications continue apace. In short, SBR  is an exciting, exacting, extensive, and expanding topic. Space-based radar systems face fundamental challenges. 
 TIONS INDEPENDENT 4HIS DEPENDS ON THE PHYSICAL LENGTH OF THE TARGET IN THE RANGE  DIMENSION  K2 4HE MINIMUM FREQUENCY SEPARATION IS  -(Z K2 M   -(Z  WILL MAINTAIN THE DIPLEX BENEFIT FOR AIRCRAFT LONGER THAN  M  FT   %QUAL ENERGY IS TRANSMITTED IN BOTH PULSES !  IMBALANCE SACRIFICES ONLY  D"  OF THE BENEFIT AT  0$.   2!$!2 2%#%)6%23   È°{Ç "OTH LINEAR AND ASYMMETRICAL NONLINEAR &- PRODUCE A RANGE ERROR AS A FUNCTION  OF DOPPLER DUE TO RANGE 
 137. D. H. 
 The real picture  of JEM is not so clean because of multiple on-aircraft bounces, straddling, and speed  variations, but centroiding of each line improves the signature estimate. The last  method of TID, ISAR, will be dealt with in another section. ISAR works well on both  aircraft and ships. 
 PORT ISOLATION   AND SINGLE TONE INTERMODULATION LEVELS 4HE ,/ DRIVE POWER SPECIFICATION DEFINES HOW MUCH ,/ POWER IS REQUIRED BY THE MIXER TO MEET ITS SPECIFIED PERFORMANCE LEVELS  4YPICALLY  THE HIGHER THE ,/ POWER  THE HIGHER THE  D" COMPRESSION POINT AND THIRD  ORDER INTERCEPT POINT 2ADAR RECEIVERS OFTEN REQUIRE HIGH ,/ DRIVE LEVEL MIXERS IN ORDER TO MEET THE CHALLENGING DYNAMIC 
 1 Range gate No. 2Binary  counterCount Sampler(a) Video First  Threshold(b) (c) Second threshold Target pulse   Figure 8.18  Block diagram of a binary integrator.   A target is identified if m echoes are counted from a possible number n, all within a certain  time interval. 
 Thus, for an operating pulse width FIGURE 11.5  One limit of transistor capability is determined by the maximum junction temperature,  which in turn is determined by the thermal time constant, and this results in very different capabilities as a  function of operating pulse width and duty cycle.160220 200 180 160 140 120 100GaAs Power Amp Transient Temperature Response 20 µsec @ 10% dutyGaAs Power Amp Transient Temperature Response 3000 µsec @ 25% dutyGaAs Die (0.004"  thk) CuMo Spreader (0.015" thk) CuMo Base (0.040" thk) τGaAs  = 170 µsec τGuMo = 825 µsec τGuMo  = 5,850 µsec 150 140 130 Temperature (°C) Temperature (°C)120 110 100 0100 200 300 400 500 Time-µsec2000 4000 6000 8000 10000 12000 14000 0 Time-µsec600 700 800 900 ch11.indd   9 12/17/07   2:25:26 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Solid-State Transmitters. 
 n°Óä  2!$!2 (!.$"//+  4HE MATRIX ELEMENTS REPRESENT THE MULTIPLYING COEFFICIENTS OF A BASIC PHASE SHIFT  O -  WHERE  - IS AN INTEGER 4HE  PHASE SHIFT CORRESPONDING TO THE ELEMENT  M N OF THE  MATRIX CAN BE WRITTEN AS   FP MN-MNM - N -    
 1499–1510, 1995. 24. K. 
     & 2#ASTELLA  h!NALYTICAL RESULTS FOR THE X Y +ALMAN TRACK ING FILTER v  )%%% 4RANS !EROSPACE AND  %LECTRONIC 3YSTEMS  .OVEMBER   VOL   PP 
 28. Golay, M. J. 
 The magnitude of the echo may be deter- mined by finding the polygonal areas on each face of the corner receiving waves reflected by the other faces, and from which the final reflection is back toward the source. The effective area is determined by summing the projections of the areas of those polygons on the line of sight;10 the RCS is then found by squaring that area, multiplying by 4ir and dividing by X2. Figure 11.12 is a collection of RCS patterns of a trihedral corner reflector with triangular faces. 
 SEC. 3.16] CITIES 103 signal represents the superposition ofreflections from the surface ele- ments located within aregion bounded bybearnwidth and pulse length. The individual targets, however, because oftheir lowabsorption and high retrodirectivity, aremore effective than the scatterers and irregularities responsible forground return and seareturn. 
 Aradarshouldnotbeexpected toprovidethesametarget detailsasareseenvisually. Anelectromagnetic sensor,whether theeyeoraradar,responds to scattering fromthosedetailsofthetargetwhicharecomparable tothewavelength ofobserva­ tion.Sincethereissuchalargedifference inwavelength between microwave radarandvisual sensors, thetargetdetailsthatareseenbyradarcanbequitedifferent fromwhatisseen visually. Whenattempting tomeasure targetsizewithahigh-range-resolution radar, an error canbeincurred sincetheextremities ofthetargetarenotalwaysgoodscatterers. 
 NOISE RATIO  TO ACHIEVE PRECISION TRACKING ON THE ORDER OF  MIL IN ANGLE AND  M IN RANGE &)'52%   A  !.&01 
 and from adjacent range gates. As many as 20 hit-reports might be generated by a single  large target.43 A post processor groups together all reports which appear to originate from the  sarlie target and interpolates to find the best azimuth, range, amplitude, and radial velocity.  The target amplitude and doppler are used to eliminate small cross section and low-speed  angel echoes before the target reports are delivered to the automatic tracking circuits. 
 Schultz, J. L., and P. Nosal: Space-Based Radar, Horizons, vol. 
 pulse repetition frequency. (The approximation holds for large  prf's and for the usual glint bandwidths which are of the order of a few hertz to several tens of  hertz.)36 For example. with a target depth D of 7 m and a frequency-agile bandwidth of  JOO MHz, the glint error is reduced by a factor of 2.6. 
 MOMENTS CODE .%#  !S A RULE OF THUMB  THE (& 2#3 OF AIRCRAFT CAN USUALLY BE COMPUTED TO AN  ACCURACY OF ABOUT  OR  D" WITH RESPECT TO MEASURED VALUES  WITHOUT RESORTING TO HIGHLY SOPHISTICATED TECHNIQUES 7HEN PRECISE 2#3 INFORMATION IS NOT ESSENTIAL  ROUGH BUT USEFUL 2#3 ESTIMATES  CAN BE MADE BY EXAMINING THE SCATTERING BEHAVIOR OF A FEW hCANONICALv SHAPES &IGURE  IS A FAMILY OF PLOTS GIVING 2#3 VERSUS RADAR FREQUENCY FOR AN OBLONG 
 STATE TRANSMITTERS IS VERY HIGH EVEN IF MAINTENANCE IS DELAYED UNTIL CONVENIENT SCHEDULED PERIODS HOWEVER  THIS ADVANTAGE SHOULD NOT BE ABUSED #ONSIDER A CASE WHERE  OF  MODULES ARE ALLOWED TO FAIL BEFORE OUTPUT POWER FALLS BELOW REQUIREMENTS  AND ASSUME THAT MAINTENANCE OCCURS AT SCHEDULED THREE 
 DIVERSITY MODES OR TO THE USE OF WIDE INSTANTANEOUS BANDWIDTH n &REQUENCY AGILITY USUALLY REFERS TO  THE RADARS ABILITY TO CHANGE THE TRANSMITTER FREQUENCY ON A PULSE 
 The use of a higher frequency for the height finder is appropriate since it can be of  shorter range tlian the 2D air-surveillance radar, and the antenna aperture can be of smaller  size for a given heamwidth. The height finder can also be made to provide good range  resolution for target counting by utilizing a narrower pulse than might be desired for a  long-range 2D air-surveilla~ce radar operating at a lower frequency.  Thus tliere are many reasons for the nodding-beam height finder being a good chow for  obtaining the third coordinate on aircraft,  Instead of mechanically rocking the entire antenna structure, the horizontal fan beam of a  height finder can be scanned in elevation by electromechanical means, such as with the  Robinson scanner, organ-pipe scanner, or delta-a (or Eagle) scanner. 
 )NTELLIGENCE !GENCYS .'!  $IGITAL 4ERRAIN %LEVATION $ATA $4%$  OR FROM ANY OTHER SUITABLE SOURCE 4HE FINITE CONDUCTIVITY AND DIELEC 
 FORMANCE IS ACHIEVED USING A STATE 
 *Certain practical considerations which prevent theuseoftheentire interval between pulses forreception ofsignals andwhich therefore setthelimit onP,even lower than c/2R (seeChap. 12)arehere ignored.. 120 LIMITATIONS OFPULSE RADAR [SEC. 
 J.C .. C.R. Burrows. 
 Usually the range-elevation profile is measured in multiple segments with separate  PRFs and pulsewidths. The lowest PRF is used to measure the longest-range portion  of the profile at the top of the elevation scan. It uses the largest pulse compression ratio  (16:1–32:1). 
 However, in a linear  FM system a strong CW signalanywhere in the total signal bandwidth can capture a limiting  receiver and cause suppression of the target echo.  Instead of the 0, n binary phase shift, smaller increments of phase can be applied in the  phase-coded pulse compression waveform. These are called po/yphase codes.16·24 The time  sidelobes of a polyphase code can be lower than those of the binary phase-coded waveform of  similar length.63•64 However, the performance of polyphase codes deteriorates rapidly in the  presence of a doppler-frequency shift and therefore they have been limited to situations where  the doppler is negligible. 
 Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.40  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 as the monopulse difference pattern. Figure 9.28 shows typical sidelobe multipath  errors for higher-elevation targets and the linearly decreasing error versus target  elevation, predicted by the above equation, for very low-elevation targets. 
 24.8 A predicted vertical-incidence ionogram is compared with observed ionograms. The arrow points to the predicted 3.2-MHz critical frequency, and the little circles give points on the predicted median sounding. The measured median of this ensemble is about 3 MHz. 
 For example, Figure 5.29 shows a rolling motion of ± 2.3° that might be  exhibited by a ship in calm seas. The roll motion might have a period of 10 seconds.  The motion of almost all the scatterers on a large combatant are moving in arcs of  circles projected as segments of ellipses to a radar observer.45 For a radar observer the  change in range, dR, associated with a roll movement is a function of the height, h, FIGURE 5.28  Range profile ship recognition45 ch05.indd   31 12/17/07   1:27:11 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 The short pulse lengths and low duty cycles typical of older  tube-type radars thus make very inefficient use of the average power capabilities of  microwave transistors. To replace the old, well-proven 5J26 L-band magnetron that  develops 500 W of average RF power at 0.1% (typical) duty cycle would require 2500  to 5000 of the 50-watt transistors just described. However, with a 10% duty cycle the  500-watt average power requirement could be provided by only 25 to 50 of the 50-watt  transistors. 
 RANGE CLOUD MEASUREMENTS THAT ARE LIMITED BY ATTENUATION  . 
 PULSE VARIA 
 4237–4240. 8. Wen, X.; Kuang, G.; Hu, J.; Zhang, J. 
  ++0NN .MD EE 
 The imaging scene is discretized. In order to represent the radar signal as a matrix, the corresponding 2-D backscatter coefﬁcient matrix is concatenated into a one-dimensional column vector by row or line: gi=[gi(1, 1),···,gi(P,1),gi(1, 2),···,gi(P,2),···,gi(1,Q),···,gi(P,Q)]T, (5) where, girefers to the vector of PQ×1, and Pis the discrete grid number of axis x.Qis the discrete grid number of axis y. According to the Formula (4), the discrete echo data can be indicated as follows: sir(t)=PQ ∑ l=1M−1 ∑ m=0gi(l)exp/bracketleftbigg −j4π λmRi(t,l)/bracketrightbigg , (6) where, λmrefers to wave length corresponding to the frequency fm.Ri(t,l)refers to the distance between the ith antenna and the lth target at time t. 
 48.Staprans, A.:High-Power Microwave Tubes,IEEEInternational Electron DevicesMeeting Technical Digest1976,Washington, D.C.,pp.245-248, IEEEPub.no.76CH1151-0ED. 49.Pickering, A.H.:Electronic TuningofMagnetrons, Microwave J.,vol.22,pp.73-78,July,1979. 50.Staprans, A.:linearBeamTubes,chap.22of"RadarTechnology," E.Brookner (ed.), ~rtechHouse, Inc.,Dedham, Mass.,1977.. 
 Noise Temperature. The usual noise that exists in a radar receiving system is partly of thermal origin and partly from other noise-generating processes. Most of these other processes produce noise which, within typical receiver bandwidths, has the same spectral and probabilistic nature as does thermal noise. 
 SIDERED BY THE SYSTEM ENGINEERS AS A SEPARATE CONTRIBUTION TO THE OVERALL RADAR SYSTEM NOISE  DISTINCT FROM RECEIVER NOISE  AND WAS ACCOUNTED FOR AT THE SYSTEM LEVEL 4ODAY  IT HAS BECOME COMMON TO INCLUDE THE !$ CONVERTER NOISE AS PART OF THE OVERALL RECEIVER NOISE #ONSEQUENTLY  IT IS IMPORTANT TO UNDERSTAND WHETHER OR NOT THE CONTRIBUTION OF THE !$ CONVERTER IS INCLUDED IN THE SPECIFICATION FOR THE NOISE FIGURE OF A RECEIVER. 
 The safety factor Ks assures that the clutter sidebands will be buried in receiver noise. Each tabulated value assumes that only one source of modulation is present. If multiple modulations are expected, an appropriate reduction factor must be pro- vided so that the composite sidebands do not exceed the tolerable value. 
 ERS OR ROCKET INTERACTIONS WITH THE AMBIENT PLASMA !MONG THE MOST IMPORTANT FROM THE RADAR POINT OF VIEW ARE THE FOLLOWING u 4RANSIENT PLASMA STRUCTURES ASSOCIATED WITH IONIZED METEOR TRAILS AT ANY GIVEN LOCA 
 /\!'pert. Ya. L.: .. 
   -AY   !$ 
 This was the first Earth Explorer Opportunity Missions, which was part  of the European Space Agency’s Living Planet Programme. The mission concept77  was selected in 1999 and subsequently launched in October 2005. Unfortunately, the  launch vehicle malfunctioned. 
 S. Rutherford: The Sun as a Test Source for Boresight  Calibration of Microwave Antennas, IEEE Trans., vol. AP-19, pp. 
 AES-19, pp. 513–520, July 1983. 20. 
 The frequency-modulated signal occupying a band equal to l/t O can be  compressed in a pulse compression filter to produce a narrow pulse at the output of the filter.  This then is one method for combining frequency scan with pulse compression, where the  angular resolution depends on the antenna beam width and the range resolution depends on  the group time delay t O•  The rrequency-scan technique is well suited to scanning a beam or a number of beams in a  single angle coordinate. It is possible to use the frequency domain to produce a TV (raster)  type of scan in two orthogonal angular coordinates by employing an array of slightly disper­ sive arrays fed from a single highly dispersive array. 
 There are many  reasons for the failure of the simple radar equation to correlate with actual performance, as  discussed in Chap. 2. _ , 9, 11 ' . 
 Jtwasplacedbetween thereceiver portoftheduplexer andthereceiver tosafeguard againstrandom pulsesfrom nearbyradarequipments whichweretooweaktofiretheconventional TRtubesinthe duplexer, butstrongenoughtodamage thereceiver. ThepassiveTR-limiter orthediode limiterhasreplaced theprotector TR.Suchdevicesareknownasreceiverprotectors. Receiver protectors alsoservetoprotectagainstpowerreflected hymismatches attheantenna. 
 It is in this region that it is advantageous to  operate low-noise receivers to achieve' maximum system sensitivity. The minimum atmo-  spheric absorption occurs when the antenna 'is vertical (pointed at the zenith), while the  462INTRODUCTION TORADAR SYSTEMS x 0 .c-L ~0 LJJ E \0MaximumL\..... c100\ '"'"'"\ '"a '" \L ::J\"5 L '" \a. 
 Even during continuous operation, a change in tuner setting may result in drifting again after the change if cavity or tuner heating varies with tuner setting. Temperature-compensated designs are available in some cases. 7. 
 MATIC IN &IGURE  )T CONSISTS OF A TRANSMITTER AMPLIFIER CHAIN  A PREAMPLIFIER FOR RECEIVING  A SHARED PHASE SHIFTER WITH DRIVER  AND CIRCULATORS ANDOR SWITCHES TO SEPARATE THE TRANSMIT AND RECEIVE PATHS THE GAIN AROUND THE LOOP MUST BE LESS THAN UNITY TO AVOID OSCILLATIONS  0OWER AMPLIFIERS FOR TRANSMITTING AT THE  ELEMENT LEVEL WOULD TYPICALLY HAVE A GAIN OF  D" OR MORE TO COMPENSATE FOR THE LOSS OF POWER DIVIDING IN THE BEAMFORMER 4RANSISTORS ARE CAPABLE OF GENERATING HIGH AVERAGE POWER BUT ONLY RELATIVELY LOW PEAK POWER (IGH DUTY 
 Soc., vol. 80, pp. 522-545, October, 1954. 
 BAND  2ADAR  "ACKSCATTER  -EASUREMENTS  OF  7HEAT   "ARLEY  AND  /ATS   7AGENINGEN .%4(%2,!.$3 #ENTER FOR  !GROBIOLOGICAL 2ESEARCH    " "RISCO  2 * "ROWN  AND ' * 3OFKO  h4HE ##23 GROUND 
 For example, after initial crossing of the detection threshold, the radar beam can be  returned to the same direction sooner than it would in normal search in order to verify that a  target was indeed detected and that the threshold crossing was not a false alarm due to noise.  This rer(ficatim1 pulse can be of greater power and/or of longer duration to increase the  probability of detection. The two-step process of (I) initial detection and (2) verification is  sometimes called sequemial detection. 
 This test can beused whenever the more general coherent oscillator locking test shows trouble. The locking-pulse mixer current should bemonitored. This can be done byswitching themeter normally used forthesignal-mixer current. 
 To know the various types of tracking techniques in volved.   4. To understand Radar Receivers, MTI filters, displays and antennas. 
 AMBIGUOUS ECHOES  WHICH CAN BE SHIFTED ABOUT IN THE RANGE 
 WORLD CONDITIONS 4HIS IS ESPECIALLY IMPORTANT FOR RADAR EQUIPPED WITH ADAPTIVE TECHNIQUES SINCE THEY MIGHT NOT BE ALWAYS FULLY MODELED IN A SIMULATION AS THEY ARE IN THE REAL 
 Although this estimate is rarely implemented, its per- formance is approached by simple estimates. Practical Detectors. Many different detectors (often called integrators) are used to accumulate the radar returns as a radar sweeps by a target. 
 Nat. Bur. Stds.)  mountainous terrain also shows no frequency dependence rrom L to X hand hut is con­ siderably lower at UHF; rough hills, desert, and cultivated farmland show a linear depen­ dence with frequency; and the backscatter from marsh varies as the~ power of frequency. 
 REINFORCED PLASTICS  AND THE CORE IS A FOAM OR HONEYCOMB )NORGANIC SKIN AND CORE SAND 
 #7 RADARS HAVING HIGH AVERAGE POWER CAN BE USED TO  OBTAIN VERY HIGH RANGE RESOLUTION FOR DETECTING VERY THIN SCATTERING LAYERS IN THE CLEAR AIR BOUNDARY LAYER -OST METEOROLOGICAL RADARS ARE PULSED RADARS HAVING DOPPLER CAPABILITY 'ROUND 
 DOPPLER SPACE  # "!('' %   !$ !('' %)!('' % %  *   $# #  ' (" %  !' %(" % 
 TO 
 FLYING TARGETS (ERE  FULL SENSITIVITY MUST BE MAINTAINED IN THE PRESENCE OF THE CLUTTER TO MAXIMIZE THE PROBABILITY OF DETECTING THE TARGET 4HE DYNAMIC 
 527-532, Apr. 21-23, 1975. 23. 
 The previously stored value Vt(t - Tp) is multiplied by the delayed channel weight Wa to form the /th-channel input to the adder forming the delayed beam. FIG. 16.24 Block diagram of a digital receiver.TRANSMITCORPORATEFEEDDR1 DR2 DR1 DRN DIGITALRECEIVERSDUPLEXERS TRANSMITTER APM1 APM2 APM1 APMNADAPTIVEPROCESSINGMODULES MODULATOR RFTIMING WAVEFORMGENERATOR ADDER ADDER ADDER AUTOMATICDETECTOR RFINPUTPREAMPLIFIER MIXERIFAMPLIFIER STALOREFERENCEOSCILLATORSYNCHRONOUSDEMODULATORA/D OUTPUTLOGICDIGITALOUTPUT A/D SAMPLINGPULSES . 
 SPECIFIC REQUIREMENTS ON $)2 REVISIT RATES DETERMINE THE SEQUENCING OF THE $)2 INTERROGATIONS AND  OF COURSE  SET THE LIMIT ON HOW MANY TASKS CAN BE ADDRESSED &)'52%  .UMERICALLY COMPUTED RAYS ILLUSTRATING MULTIPLE HOP PROPAGATION ACROSS THE EQUATORIAL ZONE  4HE ELEVATED PEAK ELECTRON DENSITY NEAR THE EQUATOR AT ^ KM IS THE !PPLETON ANOMALY. 
 Ii  applies to a fan beam, or to a pencil beam if the target passes through its center. If the target  passes through any other point of the pencil beam, the maximum signal received will 1101  correspond to the signal from the beam center. The beam-shape loss is reduced by 111s ratio of  the square of the maximum antenna gain at which the pulses were transmitted divided by the  square of the antenna gain at beam center. 
 H. Bora, N. M. 
 Although high-resolution target 3-D images can be obtained by applying the planar scanning 3-D imaging, the size of sampling data is huge, and conducting the measurement is time-consuming and the imaging efﬁciency is low. For the interferometric inverse synthetic aperture radar (InISAR) [ 24,25] method, 3-D views of the target can be obtained by applying the multi-antenna phase interference method, and data acquisition and signal processing are relatively simple, which make it easy for the system to perform functions. Thus, InISAR can be widely used in near-ﬁeld 3-D imaging. 
 g(u) = 1E(g),?i(u –y)dy, with y=kx$, (3). SEC. 5.6] SIMPLE DOPPLER SYSTEM 137 where ~(z) isthe dish illumination asafunction ofx,the transverse distance from the axis ofrotation; k=27r/i; and dO/dtisthe angular rate ofrotation. 
 radar left. Reproduced by Courtesy of the Raytheon Company. Figure 1.24 - Effects of sea on PPI displays of radars having different wavelengths. 
 BAND RADAR  THEY WILL PROVIDE THE FULL FIRE CONTROL SENSOR FUNCTIONS FOR THE 'ROUND 
 Stand. Note 318, Aug. 5, 1965. 
 As this is generally true of most waveguide feeds, a perfectly symmetrical antenna  pattern is difficult to achieve in practice. The rectangular guide may he used, liowever, for  fccding all asymmetrical section of a paraboloid that generates a fail beam wider in the I1  plane than in the E plane.  When more directivity is required than can be obtained with a sinlple opetl-ended  waveguide, some form of waveguide horn may be used. 
 Switch unit type 25 [ 7].Airborne Maritime Surveillance Radar, Volume 1 2-12. for the purpose of switching off the motor switch unit. Receivers designed by Pye are illustrated in ﬁgure 2.10and those by Cole in ﬁgure 2.11. 
 ING TARGETS  0D      DETECTION 
 IEE, vol. 109R, pp. 445 -446, Novcm-  her, 1962. 
 1947.  2. Lawson, J. 
 IRE, vol. 41, pp. 1035-1037, August 1953. 
 K. Raney, “Considerations for SAR image quantification unique to orbital systems,” IEEE  Transactions Geoscience and Remote Sensing , vol. 29, pp. 
 (Courtesy Westinghouse Elec- tric Corporation.) For some purposes the extended feed is not placed about the focal plane at all. If we consider the reflector as a collector of parallel rays from a range of angles and examine the converging ray paths (Fig. 6.17) it is evident that a region can be found that intercepts most of the energy. 
 BASED FACILITIES  SINCE THE MORE COMPLICATED WAVEFORMS FROM ICY  SURFACES REQUIRE ITERATIVE DEVELOPMENT OF SUITABLE PROCESSING ALGORITHMS BY INVESTIGA 
 TRIES  WITH HUNDREDS OF RESULTING PAPERS 4HE READER SHOULD SEARCH THE LITERATURE FOR THESE RESULTS  WHICH ARE FAR TOO  NUMEROUS TO REFERENCE HERE -ANY OF THE MORE RECENT  3!2S n ALSO PROVIDE INFORMATION ON POLARIMETRIC RESPONSES 2ESULTS OF MOST OF THESE MEASUREMENTS ARE SUMMARIZED IN 5LABY  -OORE  AND  &UNG AND 5LABY AND $OBSON -ORE COMPLETE SUMMARIES OF THE EARLIER WORK AND  NEAR 
 SURES TECHNIQUES MUST COVER ! .AVAL 2ESEARCH ,ABORATORY SYSTEM CALLED 42!+8 4RACKING 2ADAR !T + A AND  8 BANDS  WAS DESIGNED FOR  INSTRUMENTATION RADAR APPLICATIONS FO R MISSILE AND TRAINING  RANGES  )TS PURPOSE WAS TO ADD PRECISION TRACKING ON TARGETS  ESSENTIALLY TO hSPLASHv  AND PROVIDE PRECISION TRACKING AT +A BAND IN AN ENVIRONMENT OF 8 
 Signal averaging or integration of the  samples can increase the effective sensitivity by the amount of averaging and this can  be typically 10 to 30 dB. The ratio of the peak transmitted signal to the mean receiver  noise level can be up to 150 dB. The antennas that can be used with time-domain GPR are limited to linear phase  designs such as resistively loaded dipoles, TEM horns, or Impulse Radiating Antennas  (IRAs). 
 30, pp. 853–858, 1992. 77. 
 Since the jammer power received at the radar varies inversely as the square of the distance  between radar and jammer (one-way propagation), while the radar echo power varies with  distance inversely as the fourth power (two-way propagation), there will be some distance  below which the radar echo will exceed the jammer signal. This is called the self~scrc~~~tiir~y  rcrnye, or the crossover range, and is approximately  P,, G, cr B, J ~,2, = - - -- -- -  PI, G, 411. B, S  where PI, = radar transmitter power  I),, = jammer transmitter power  G, = radar antenna gain  Gj =jammer antenna gain  0 = target cross section  B, = jammer bandwidth  B, = radar signal bandwidth  J/S = jammer-to-radar signal (power) ratio at the output of the IF required to mask the  radar signal  A jammer located on a target of cross section a will overpower the radar if the jammer is at a  range R,, or greater. 
 DENSITY PLOT OF ANGLE NOISE BELOW THE FREQUENCY CORRESPONDING TO THE RADAR SERVO BANDWIDTH WITH THE TOTAL AREA UNDER THE POWER 
 These ten pulses are processed by the delay-line canceler  and the doppler filter-bank, to form eight doppler filters. Thus, the radar output is divided into  approximately 2,920,000 range-azimuth-doppler cells. Each of these cells has its own adaptive  threshold. 
 Catalog  no. AD-AOlO 478.  45. 
 13.27. The numbers alongside each indicate to which grid thevarious signals areapplied. 1The main switch isopened shortly before abasic pulse isexpected, inamanner that will bedescribed presently. 
 .   -4) 2!$!2  Ó°Îx FILTER CHARACTERISTICS 7ITHIN THIS CHAPTER  REFERENCE TO  BINOMIAL 
 Quilfen, B. Chapron, F. Collard, and D. 
      
 Randall: The Cavity Magnetron, J. Inst. Elect. 
 THE RADAR EQUATION 27  probability· of detection Pd is therefore  Pd= ("'1,i(R)dR  ' I' 1 ·"" R ( R2 + A2 ) (RA) / ---exp - 10 -· dR  ' V r t/t O 2t/t O t/J 0 (2.28)  This cannot he evaluated by simple means, and numerical techniques or a series approxima­ tion must be used. A series approximation valid when RA/t/1 0 ~ l, A ~ IR -A I, and terms in  A 3 and beyond can be neglected is9  where the error function is defined as  err z  A graphic illustration of the process of threshold detection is shown in Fig. 2.6. 
 and P.A. Mcinnes: On the Specilkation of an Antenna Pattern for a Synthetic Aperture  Radar. /11tt·n111cio11al C1111/cr<'IIC<' R,.1/JAR-77. 
 Because ofthis grossness ofradar vision, the objects that can usefully beseen byradar arenot asnumerous asthe objects that canabe distinguished bytheeye. Radar isatitsbest indealing with isolated targets located inarelatively featureless background, such as aircraft inthe air, ships ontheopen sea, islands and coastlines, cities in aplain, and thelike. Though modern high-definition radar does afford afairly detailed presentation ofsuch acomplex target asacity viewed from the air(see, forexample, Fig. 
 Often the results are similar to  those predicted by the log-normal distribution, as evidenced by the experimental data  shown in Figure 20.22 b, which gives the power-level distributions for the example  shown in Figure 20.21. These approximately log-normal distributions are typical for  benign conditions. Tracking. 
 Although the swath is 1800 km  wide, the variety of aspect and polarization coverage limits the science-compliant wind  vector retrievals to strips from 250 km to 800 km either side of the ground track. Aquarius.  The Aquarius  mission is designed to map sea surface salinity, for  which L band radiometric sensing of the ocean’s emissivity is the primary measure - ment. 
 RESPONSE &)2    FILTERS 4HEN THE RADAR MAY CHANGE ITS 02& ANDOR 2& FREQUENCY  AND TRANSMIT ANOTHER  #0) OF . PULSES 3INCE MOST SEARCH RADARS ARE AMBIGUOUS IN DOPPLER  THE USE OF DIFFERENT   &)'52%  "LOCK DIAGRAM OF -4$ )) SIGNAL PROCESSOR . Ó°n  2!$!2 (!.$"//+  02&S ON SUCCESSIVE COHERENT DWELLS WILL CAUSE THE TARGET RESPONSE TO FALL AT DIFFERENT  FREQUENCIES OF THE FILTER PASSBAND ON THE SUCCESSIVE OPPORTUNITIES DURING THE TIME ON TARGET  THUS ELIMINATING BLIND SPEEDS %ACH DOPPLER FILTER IS DESIGNED TO RESPOND TO TARGETS IN NONOVERLAPPING PORTIONS  OF THE DOPPLER FREQUENCY BAND AND TO SUPPRESS SOURCES OF CLUTTER AT ALL OTHER DOPPLER FREQUENCIES 4HIS APPROACH MAXIMIZES THE COHERENT SIGNAL INTEGRATION IN EACH DOPPLER FILTER AND PROVIDES CLUTTER ATTENUATION OVER A LARGER RANGE OF DOPPLER FREQUENCIES THAN ACHIEVABLE WITH A SINGLE -4) FILTER 4HUS  ONE OR MORE CLUTTER FILTERS MAY SUPPRESS MULTIPLE CLUTTER SOURCES LOCATED AT DIFFERENT DOPPLER FREQUENCIES !N EXAMPLE OF THE USE OF AN -4$ DOPPLER FILTER BANK AGAINST SIMULTANEOUS LAND AND WEATHER CLUTTER 7X  IS ILLUSTRATED IN &IGURE  )T CAN BE SEEN THAT FILTERS  AND  WILL PROVIDE SIGNIFICANT SUPPRESSION OF BOTH CLUTTER SOURCES 4HE OUTPUT OF EACH DOPPLER FILTER IS ENVELOPE 
 SNR is the ratio of the signal level to that of the  noise. SNR is typically expressed in decibels (dB). The maximum receiver SNR is  set by the noise contribution and maximum signal capability of every component  in the chain; however, since the limiting technology is often the Analog-to-Digital  (A/D) converter, the preceding components and gain structure are often chosen such  that the maximum SNR is driven by the performance of the A/D converter. 
 The Rieke diagram shows that a change in the VSWR which moves the operating  point of the magnetron into either the sink or antisink regions can cause the magnetron to  operate poorly. Ferrite isolators are sometimes used to avoid subjecting the magnetron to high  VSWR. A 10-dB isolator, for example, lowers a VSWR of 1.5 to a value of 1.14. 
 17.26  17.6 Dynamic-Range and Stability  Requirement s  ..........  17.26  Dynamic Range  .................................................  17.26 Stability Requireme nts  ....................................... 
 The validity of any ground-return theory must depend on the mathematical model  used to describe the surface, as well as on the approximations required to obtain  answers. Even the simplest ground surface, the sea, is extremely difficult to describe  accurately; it is homogeneous to beyond the skin depth, contains relatively modest  slopes, and (except for spray) has no part above another part of the surface. At grazing  angles, shadowing of one wave by another might occur. 
 Balanis, Antenna Theory Analysis and Design , Chapters 13 and 15, New York: John Wiley  and Sons, 1982. 36. A. 
 TO 
 Because this amplitude weighting produces a taper  loss on receive, using full amplitude and phase control for nulling the radiation pattern  is less of a concern than on transmit. The incorporation of adaptive nulling into phased array antennas allows phased  arrays to have adaptive antenna patterns on receive. Adaptive techniques are used to  sense and automatically respond to a time-varying interference environment. 
 STATE RADARS NEED LITTLE ANALOG CIRCUITRY WITHIN THEIR DESIGNS  THEY OPERATE ON LOW VOLTAGES AND HAVE NO TIME 
 ASSISTED '-4 GEOLOCATION . 
 AGILITY OR FREQUENCY 
 CAL DISTANCE BETWEEN THE RADAR AND THE SURFACE BELOW )N AIRBORNE APPLICATIONS  THE RESULTING hALTITUDEv IS A MEASURE OF THE CLEARANCE BENEATH THE AIRCRAFT 7HEREAS THE . £n°Îä  2!$!2 (!.$"//+  MAIN OBJECTIVE OF A SPACE 
  
 T. Taylor, “Design of circular apertures for narrow beamwidth and low sidelobes,” IEEE Trans .,  vol. AP-8, pp. 
 12Bean.B.R.E.J.Dutton.andB.D.Warner: Weather EffectsonRadar,chap.24of"RadarHand­ hook."M.1.Skolnik(cd.),McGraw-HilI BookCompany, NewYork,1970. I),Schelling. J.C.CR.Burrows. 
   OPPORTUNITY  WHICH ARE DESIGNED FOR OTHER PURPOSES BUT FOUND SUITABLE FOR BISTATIC OPER 
 30. A. Haskell and B. 
 430 R-l? (!OIIPONENTS [SEC. 11.12 arrangement istherefore aback-of-dish mounting with short waveguide runs tothe antenna, aswas recommended inSec. 11.10. 
 POWER 3I "*4S IS TO MAINTAIN A UNIFORM HIGH CURRENT  DENSITY OVER A LARGE EMITTER AREA WITH A MINIMUM TEMPERATURE RISE (IGH 
 The rel/'lIlIci plalefeedusestheprinciples ofmicrowave structures toprovide efficient power division. Itis.insomerespects, acrossbetween theconstrained feedandthespacefeed. Constrained feed.Figure8.21showsatwo-dimensional-scanning arraywhichissometimes knownasaparallel-series feed.Eachelement hasitsownphaseshifter.Aseparate command mustbecomputed bythebeam-steering computer anddistributed toeachphaseshifter.The powerdistribution tothecolumns isbyparallel feed.Thepowerineachcolumn isshown beingdistributed byaseriesfeedtotheverticalelements.Ifthiswereaparallelfeeditwouldbe calledaparallel-parallel feed.(Seriesfeedsareshownheresoasnottooverlycomplicate the figure.Series-parallel orseries-series arrangements arealsopossible.) Alltheelements which lieinthesamecolumn utilizethesamephaseshifttosteerthebeaminazimuth. 
 Remote Sens. 1998 ,19, 1133–1146. [CrossRef ] 21. 
 Also see L.M. Ulander et al., “Detection of concealed ground  targets in CARABAS SAR images using change detection,” Proceedings SPIE , vol. 3721,   p. 
 It soon became clear that too many systems were being deployed for the capacity of the 176 Mc/s channel,with spectrum overcrowding. The beacon channel was therefore separated from the IFF channel for Lucero Mk. II. 
 This essentially results in the theoretical crossrange resolution  of Eq. 17.2. Stripmap SAR. 
 252. Sensors 2019 ,19, 346 When using the BP algorithm, the pixel size should be small enough to ensure that the scattering characteristic of each pixel is accurate. If the pixel size is too small, it will cause a substantial amount of computation. 
 Rev.• vol.25,no.I,pp.70-65,July,1964. ~6.Lind,G.:Reduction ofRadarTracking ErrorswithFrequency Agility,IEEETrans.•vol.AES-4,pp. 410416, May.1968. 
 sin 27T fst  cos 27T fst  Elevation  servo  amplifier  Azimuth  servo  amplifier  Figure 5.3 Block diagram of conical-scan tracking radar. Elevation-angle  error detector  Azimuth-angle  error detector Error  signal  The receiver is a conventional supcrheterodyne except for features peculiar to the conical­ scan tracking radar. One feature not found in other radar receivers is a means of extracting the  conical-scan modulation, or error signal. 
 VARYING THRESHOLD THE 34# THRESHOLD  ! RANGE GATE BY RANGE GATE COMPARISON IS MADE OF THE CORRELATIONS IN THE  ! AND "  CORRELATORS  AND IF A RANGE GATE CORRELATES IN ! AND NOT IN "  THAT GATE IS BLANKED OUT OF THE THIRD CORRELATOR  THE  # CORRELATOR 4HE  # CORRELATOR RESOLVES THE RANGE  AMBIGUITIES WITHIN THE MAXIMUM RANGE OF INTEREST !N ALTERNATIVE MECHANIZATION IS TO REPLACE THE RANGE 
 Lett. 2016 ,13, 656–660. [ CrossRef ] ©2019 by the authors. 
 The likelihood of overdetec-  tion of a target will depend on how the volirme is scanned. To avoid this problem the detection  tiecision rliight have to be delayed until the neighboring beam positions have been scanned.  After a detection decision is made it must be correlated against existing tracks to determine  lvhether it is a new target or an existing target already in track. 
 3.5), also can be affected by the evaporation  duct.JR On the positive side, the evaporation duct, when used with a properly sited antenna,  can provide extended range against surface targets or low-flying aircraft considerably beyond  that which would be expected from a uniform atmosphere.  Prediction of refractive effects. The effect of atmospheric refraction on electromagnetic propa­ gation can be determined from a knowledge of the variation of index of refraction with altitude  over the path of propag~tion. 
 RANGE CONTOURS  DEFINE THE GROUND AREA THAT CONTRIBUTES TO CLUTTER IN THE SELECTED RANGE GATE 4HE FIVE NARROW HYPERBOLIC BANDS ISO 
 ANGLE GAIN ENHANCEMENT TO COUNTER THE HIGH 
 1978. See also same title and author in IEEE EASCON '76  Record, pp. 30-A to 30-H. 
 Finally, inpractical cases, arange isreached forwhich the beacon is interrogated nomatter which way theantenna ispointed. Itisalso clear that reduction ofthe radiated power would produce anarrowing ofthe sector ofinterrogation ofany particular beacon, but would lead tofailure tointerrogate those atgreatest range.. 258 ItAl)AIt BEACONS [S,,c, S3 Similar considerations apply tothe reply link. 
 #/5.4%2-%!352%3   Ó{°ÈÎ  " $ #ARLSON  h#OVARIANCE MATRIX ESTIMATION ERRORS AND DIAGONAL LOADING IN ADAPTIVE ARRAYS v  )%%% 4RANS  VOL !%3n  NO   PP n  *ULY   ! &ARINA  0 ,ANGSFORD  ' # 3ARNO  , 4IMMONERI  AND 2 4OSINI  h%##- TECHNIQUES FOR  A ROTATING  MULTIFUNCTION  PHASED 
 This is  nc v= (26.1) Refractivity and Modified Refractivity in the Troposphere.  The normal  value of the refractive index, n, for the atmosphere near the Earth’s surface varies  between 1.000250 and 1.000400. For studies of propagation, the index of refraction  is not a very convenient number; therefore, a scaled index of refraction, N, called  refractivity , has been defined. 
 J Appl.Phys.,vol.30,pp.1417-1419, September, 1959. 52.Hogg,D.C,andW.W.Mumford: TheEffective NoiseTemperature oftheSky,Microwave J,vol.3. pp.80-84,March,1960. 
 £Ó°{  2!$!2 (!.$"//+  4HUS  THE EDGE ANGLE FOR A ROUND REFLECTOR IS  AEDGE ¤ ¦¥³ µ´ARCTAN$ F   !NOTHER USEFUL PARAMETER IS THE DISTANCE R  FROM THE FOCAL POINT TO A POINT ON THE REFLECTOR  RFXY F       ! PERTURE 'AIN AND ,OSSES  4HE GAIN OF THE REFLECTOR ANTENNA IS ONE  OF ITS MOST  IMPORTANT PARAMETERS )T IS CONVENIENT TO DESCRIBE THE REFLECTOR ANTENNA GAIN WITH REF 
 E. (ed.): " Propagation of Sliort Radio Waves," MIT Radiation Laboratory Series, vol. 13,  Mcciraw-Ilill l3ook Conipa~iy, New York. 
 SIDELOBE ANTENNAS HAS ACCEL 
 The rapid tuning over a narrowband for purposes of providing frequency agility is  sometimes called dither tuning.39 In addition to being capable of rapid tuning over a narrow­ band, these tubes also can be tuned to a frequency over a broadband in the normal manner  using a geared drive. The tuning mechanism may be controlled by a servo motor so as to select  electrically any specific frequency within the operating band either manual.ly or on an automa­ tic, programmed basis. With servo-motor control, the tube can he tuned from one rrequcncy to  another in under 0.1 second. 
 77. J. R. 
 TIONS OF CONDITIONS AND NONSEQUITURS NOTED ABOVE  AS WELL AS THE LACK OF A PROPER THEORY ARGUED FROM FIRST PRINCIPLES 4HE FAILURE OF THIS MODEL TO ACCOUNT FOR SEA SPIKES AND OTHER NON 
 This architecture provides a higher  throughput  than the nonpipelined version, which means that the final result can be  produced at a much higher sample rate, which is inversely proportional to the delay  of a single stage. The latency  of a pipelined processor refers to the delay experienced  between the time a new data sample is entered into the processor and the time that  the result based on that input is available on the output. The eight-stage, pipelined  CORDIC processor shown in the figure would have a latency equivalent to eight clock  periods and a throughput equivalent to the clock rate (i.e., once the pipeline is filled  and the first result is available on the output, successive clocks will produce new out - puts at the clock rate). 
 DIGITAL BASEBAND SIGNALS 4HE RADAR PERFORMS PLATFORM MOTION COMPENSATION ELECTRONICALLY AS PART OF THE  34!0 ARCHITECTURE 4HE RADAR IMPLEMENTS AN ELEMENT 
 Remote. Sens. 2018 ,10, 666. 
 It need not be gaussian. If the noise is not white, Eq. ( 10.1) may be  modified as discussed later in this section. 
 T   8 
 Theresultswillnotbegreatlydependent uponthe particular valuesofsusceptance andconductance chosen.Similarly, thevariation oftheob­ servedquantities canbestudiedasafunction oftheloadpresented tothemagnetron, withthe inputparameters-magnetic fieldandcurrent-likewise chosenforconvenience. Theplotof theobserved magnetron quantities asafunction oftheinputcircuitparameters,·[or somefixed load,iscalledtheperformance chart.Theplotoftheobserved quantities asafunction ofthe loadconductance andsusceptance, forafixedmagnetic fieldandanodecurrent, iscalleda Riekediagram, oraloaddiagram. Anexample ofthecoaxialmagnetron performance characteristics isshowninFig.6.6a. 
 (chirp, multiphase-shift-keyed, etc.), must all be accommodated with a high prob- ability of intercept (POI) and a low false-alarm rate (FAR).4 The range at which a radar emission is detected by an RWR depends primarily on the sensitivity of the receiver and the radiated power of the victim radar. The calculation of the warning range can be obtained by the basic one-way beacon equation, which provides the signal-to-noise ratio at the RWR: (SU-&M£)(«bH where P is the radar radiated power, R is the range from the RWR to the radar, Gf is the transmitting-antenna gain of the radar, Gr is the receiving-antenna gain of the RWR, \ is the radar wavelength, the quantity kTsB is the total system noise power of the RWR, and L is the losses. Equation (9.1) is the basis of performance calculation for an RWR. 
 through zero ontheway from acceleration todeceleration willnothave its velocity changed and can betaken asareference electron. Inthespace 1Klystrons and“Microwave Triodss,Vol. 7,Radiation Laboratory Series.. 
 The antenna design was  based on horizontal runs of 32 waveguides, each center-fed. Ferrite phase-shifters,  one for each waveguide, controlled the transmit and receive beam shape and boresight  in elevation. The electronic beam-selection enabled RADARSAT-1 to incorporate  ScanSAR.† Thus, the resolution options for RADARSAT-1 range from 8 m by 8 m  (single look) 45-km swaths (fine mode), to 100 m by 100 m (8 looks), 510 km swaths  (ScanSAR Wide). 
 20, 1979. 50. Miller, D. 
  
 M. Zatman, “Digitization requirements for digital radar arrays,” in Proceedings of the 2001  IEEE Radar Conference , May 1–3, 2001, pp. 163–168. 
 Feedthrough lens arrays acting as an RF lens and reflectarrays acting like a parabolic reflector may use any of the described multihorn or multimode feeds, and the same general factors in optimizing a feed apply. Monopulse angle-error sensing can be accomplished in a corporate-feed array by using the two halves of the array (the top and bottom halves can also be used for elevation) as a phase- comparison tracker. Array antennas which use the two halves of the aperture for phase-comparison angle error sensing generally provide a good taper for the sum pattern, but the difference-signal E field across the array reaches a peak toward the center with a sudden 180° phase change. 
 Bath and G. V.Trunk7.1 7.1  Introduction / 7.1 7.2  Automatic Detection / 7.1 7.3  Automatic Tracking / 7.22 7.4  Networked Radars / 7.46 7.5  Unlike-sensor Integration / 7.49 Chapter 8 Pulse Compression Radar Michael R. Ducoff and Byron W. 
 Under the look directions of 0◦ and 180◦, the brightness variations are both dark-bright-dark from the outside to the inside of the eddy spirals. Meanwhile, under the look directions of 90◦and 270◦, the brightness variations are both bright-dark-bright. This indicates that the brightness variations along the eddy spirals are the same in two parallel look directions. 
 WAY PATH THROUGH THE GROUND MATERIAL '02 WORKS WELL THROUGH MATERIALS SUCH AS GRANITE  DRY SAND  SNOW  ICE  AND FRESH WATER  BUT WILL NOT PENETRATE CERTAIN CLAYS THAT  4!",%  -AIN !PPLICATIONS OF '02 !RCHAEOLOGICAL INVESTIGATIONS "RIDGE DECK ANALYSIS$ETECTION OF BURIED MINES ANTI 
 Bistatic radar coverage, like monostatic radar coverage, is determined by both sensitivity and propagation. Bistatic radar sensitivity is set by the contour of constant (S/N)min and the oval of Cassini. Bistatic radar propagation requires a suitable path between the target and both sites and must include the effects of multipath, diffraction, refraction, shadowing, absorption, and geometry. 
   IS ESSENTIALLY AN IMPROVED  VERSION OF THE %23 
 18.20. The microwave resolver is a mechanically rotated RF coupling loop in circular waveguide. The azimuth and elevation difference signals are excited in this guide with E-field polarization ori- ented at 90°. 
 O., and P. C. Waterman: Scattering Modeling: Investigation of Scat- tering by Rough Surfaces, MITRE Corporation, Kept. 
 8. Origins of Radar: Background to the Awards of the Royal Commission, Wireless World, vol. 58,  pp. 
 This lackofaconvenient thermal pathtodissipate heatlimitsitspowerhandling capability. However, inonedesign,31.32theheattransfer problem wasovercome byhavingtheaxially. 292 INTKOIIUCTION TO RAVAK SYSTEMS  located garnet bar directly cooled by a low-loss liquid dielectric that was allowed lo flow alotlg  the surface of the garnet material. 
 At the highest orbital altitude, a 10- by 30-m phased array that contained 15,000 radiating elements or modules was designed. The modules delivered an average power of 6 kW, and the radar required a prime power of 3OkW. REFERENCES 1. 
 ATMOSPHERICv RE 
 The output of the test cell is the  radar output. The spacing betwen the taps is equal to the rang? :esolution. 'The o~iputs from  the delay line taps are summed. 
 D. Rawliffe, “Some early developments in synthetic aper - ture radar systems, IRE Transactions on Military Electronics , vol. MIL-6, no. 
 The yellow rectangle in Figure 3b deﬁnes the test stretch of Lungui road of interest in our experiment. Two major bridges, namely the Rongguite and Anlite Bridges, are contained in the test highway. Figure 3c shows the corresponding location of the test area on the China map. 
 84.McFee, R.,andT.M.Maher:EffectofSurfaceReflections onRainCancellation ofCircularly Polarized Radars,IRETrans.,vol.AP-7.pp.199-201, April,1959.. 85. Beasley. 
 566-571. July, 1978.  75. 
 Maximal-length sequences are of odd length. In many radar systems it is desirable to use sequence lengths of some power of 2. A common procedure is to insert an extra O in a maximal-length sequence. 
 25.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 Digital Filters and Applications.  This section  describes several of the major forms of digital filters  and how they are used in radar signal processing. Finite Impulse Response (FIR) and Infinite  Impulse Response (IIR) Filters. 
 15. Mentzer. J. 
 The process of initiating and maintaining track can be very cfe~nantl-  Table 8.1 Waveforms used in AN!FPS-85 satellite stlrveillance radar1 ''  Name Description Primary function  1. Search chirp pulse  7. Search simple pulse  3. 
 109. M. Scott, “Sampson MFR active phased array antenna,” in IEEE International Symposium on  Phased Array Systems and Technology , October 14–17, 2003, pp. 
 vol. 20, pp. 1077–1091, 2003. 
 31  Antenna scan rate. The sea clutter background does not change significantly during the time  the usual civil-marine radar antenna (with a 20 rpm rotation rate) scans by a particular  clutter patch. That is, the sea can be considered" frozen" during the observation time. 
 GROUND ECHO  16.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 Bistatic Measurements.  Measurements of ground return when the receiver and  transmitter are separated are comparatively rare. These measurements are very difficult  to make from aircraft because it is necessary that both transmitter and receiver anten - nas look at the same ground point at the same time and that the signal be correlated  with known antenna look angles. 
 Some of the energy reflected by the paraboloid enters the feed and acts as any other wave  traveling in the reverse direction in the transmission line. Standing waves are prodi~ced along  the line, causing an impedance mismatch and a degradation of the transmitter performance.  The mismatch can be corrected by an impedance-matching device, but this remedy is effective  only over a relatively narrow frequency band. 
 This occurs because the primary modulation with a  6:9:7:8 pulse-interval ratio looks like a target at maximum-response speed, whereas  the primary modulation with a 6:8:9:7 pulse-interval ratio looks like a target at one- half the speed of maximum response. Because it is desirable to average the transmitter  duty cycle over as short a period as possible, the 6:9:7:8 pulse-interval ratio would  probably be chosen for a practical system. Once Eq. 
 Springs Aand Bposition thetube holding thecarbon pile. I Electronic Speed Controls.—The Eclipse-Pioneer Division ofBendix Aviation has recently developed anelectronic speed control foruse on motor alternator sets of1500-va capacity and larger. This regulator is designed tohold speed within the limits ofArmy-Navy Specification AN-I-lo. 
 Fortunately, the  platform-motion spectrum is narrow in the forward sector of coverage where offset  error is maximum. An offset error of one-hundredth of the PRF would yield a 26 dB  improvement factor for a double canceler with an input clutter spectrum whose width  FIGURE 3. 7 Block diagram of a radar illustrating the signal flow path of the TACCAR control loop ch03.indd   7 12/15/07   6:02:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Forexample, anOTHradarwith1200anglecoverage andarangeinterval extending from 1000to4<i)okmcansurveyanareaofalmostsixteenmillionsquarekilometers'. Aircraft at anyaltitude withinthisregioncanbedetected, located, andtracked soastoprovide a cost-effective over-ocean air-traffic-control capability. Targetheightisnotobtained withthis OTHradar.(Norisheightobtained withtheusualmicrowave air-traffic-control radars.) Itis possible toutilizemodified HFcommunications equipment astransponders oneachaircraft whichcanrelaybacktotheradartheheightoftheaircraft asdetermined bytheonboard altimeter, aswellastheidentityoftheaircraft. 
 For example, if a 30-MHz IF receiver is being gated at a 110-kHz PRF, the 272d harmonic of the gating transient will fall at 29.92 MHz and the 273d at 30.03 MHz. Either of these harmonics may be within the doppler passband and therefore appear in the output. Although high- order harmonics of the gating transient are relatively small, they may be large compared with the signal since gating occurs early in the receiver. 
 pp. 2OOU -2001. December; 1966. 
 It isespecially noticeable on the longer range scales.d(1.22 h) = Figure 1.8 - Sub-refraction. Figure 1.9 - Super-refraction. 11Extra Super-refraction or Ducting Mostradaroperatorsareawarethatatcertaintimestheyareabletodetect targets atextremelylong ranges, but atother times theycannot detect targetswithin visual ranges, even though their radars may be in top operatingcondition in both instances. 
 TO 
 The limiter may be set either to prevent saturation of any subsequent stage or to allow saturation of the A/D converter, a device which is usually designed to cope with modest overload conditions. The IF phase detector described in Sec. 3.10 requires a limiter to create an output dependent on phase and independent of amplitude. 
 Some CFAs have cold cathodes and are started by applying RF drive. The RF drive power must be applied in time to permit the tube to start drawing current before the cathode voltage pulse overshoots the proper operating voltage. How- ever, even when there is a drift region in the CFA, as shown in Fig. 
 The motion of the feed is  generally circular. The electromagnetic path within the antenna structure is designed to con­ vert the circular motion of the feed to a linear motion of the antenna beam. In some designs the  beam sweeps across a plane and then returns by the same route. 
 In this map target SNR levels are estimated comparing their powers with respect to the background thermal noise level. 126. Sensors 2019 ,19, 252 From this map it is possible to notice that all the relevant targets have been detected with a SNR greater than 35 dB, allowing an interferometric displacement measurement with precision greater than one tenth of a millimeter [ 5]. 
   PP n    * # 7ILTSE  3 0 3CHLESINGER  AND # - *OHNSON  h"ACK 
 A specific de-sign for an S -band Radar with a 100:1 (100  µs to 1µs) non- linear pulse compression system is  presented. For Doppler shifts up to 10  kHz (1000 knots radial v elocity) this design maintains a  peak side lobe level below -55 dB and an integrated side lobe level less than -37.9 dB with a  mismatch loss of 0.6 dB. The receiver uses a 5- pole Bessel filter with a 0.7 MHz bandwidth,  the A/D converter sampling rate is 2.5  MHz, and the FIR filter pulse compressor has an i m- pulse response duration which exceeds the Radar pulse -length by only 35%. 
 CUSSED IN 3ECTION   THE DOPPLER FILTER BANK WILL USUALLY BE EFFECTIVE AGAINST MOVING CLUTTER 4HIS REQUIRES THAT THE INDIVIDUAL FILTERS BE DESIGNED WITH A LOW SIDELOBE LEVEL IN THE REGIONS WHERE CLUTTER MAY APPEAR AND THAT EACH FILTER BE FOLLOWED BY APPROPRI 
 33. D. L. 
 Radiating elements aregenerally oflow gain,asisconsistent withthebroad-beamwidth neededforwide-angle scanandthenarrow sracingtoavoidgratinglobes.Moredirective elements canhelIsedwhenthescanning ofthe heamneednotbeoverawideangle.Themoredirective theelement, thefewerthatareneeded tofillagivenaperture. Another important consideration· intheselection ofanantenna elementandthedesignof anarray,isthemutualcoupling between theradiating elements. Whenthelfieldintensity patternofanarrayantenna was.considered previously [Eq.(8.3)]itwasassumed thatthe elemental radiators wereindependent ofoneanother. 
 This situation may he relieved hy replacing the  2rr modulo phase shifters with delay lines.  A similar phenomenon occurs in the series-fed array when the energy is radiated or  received at or near the broadside direction. If a short pulse is applied at one end of a series-fed  transmitting array, radiation of energy by the first element might be completed before the  remainder of the energy reaches the last element. 
 35. “Technical parameters for radar target enhancers” ITU Recommendation M.1176, International  Telecommunication Union, Geneva. 36. 
 [ CrossRef ][PubMed ] 38. Gutierrez, F.; Parise, M.; De Waele, J.; Jourde, H. A review on natural and human-induced geohazards and impacts in karst. 
 The waveform generator, switch unit, heading control unit and indicator unit were essentially the same as ASV Mk. IIIB (including range indicated in nautical miles, without the slant-range curves, and a Leigh Light marker), although changesto the indicator unit are discussed below. 4.2.1 Scanner type 67 The scanner type 67 was similar to the scanner type 51 used on ASV Mk. 
 SPARX Design Recently, in order to overcome the current limits of the ground based interferometric SAR systems, IDS GeoRadar developed SPARX: an X-band MIMO array. The SPARX array consists of 16 transmit and 16 receiver antennas, organized in independent sub-modules and geometrically arranged in order to synthesize a uniformly spaced virtual array of 256 elements. In Figure 4is shown the SPARX block diagram: a radar sensor generates an X-band RF signal with a central frequency of 9.7 GHz and an instantaneous bandwidth of 275 MHz. 
 ch18.indd   11 12/19/07   5:13:59 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 ITY READ hGEOPHYSICAL INFORMATION POTENTIALv  OF 3!2 IMAGERY OVER NATURAL TERRAIN COMPOSED OF DISTRIBUTED SCATTERERS 4HE GOVERNING EXPRESSION IS  THE 3!2 IMAGE QUAL 
 1O.29.—V-I characteristics of4J77 mag- netron. Field, 2700 gauss; A=11.140 cm.magnetron, magnetic field, and cathode condition. Short-circuit and open-circuit conditions must beallowed forif thepulser isnottobedamaged. 
 E <l Time~Figure 11.5Shapt:ofrectangular pulst: afterpassingthrough aband-limit~d r~c­ tangular filter. JThisisareasonably goodapproximation foralmostanyvalueofBt.Therefore thermserror inthetime-delay measurement fora"rectangular" pulseofwidtht,limitedtoabandwidth B, isapproximately (r)1/2 bTR~4BEINobandwidth-limited rectangular pulse (11.20) (11.22)Thepulsewidth tintheaboveexpression isthatoftheperfectly rectangular pulsebeforeband limiting.Itisagoodapproximation tothewidthoftheband-limited pulsewhenBtislarge. Equation (11.20)isthesameasEq.(11.5)butisderivedinatotallydifferent manner. 
 Simulations with point targets and real SAR images are performed to test the proposed method in Section 5and conclusions are drawn in Section 6. 2. Multi-Pass Squinted SAR The imaging geometry of MPS SAR is shown in Figure 1a, where X,Y,Z, and S represent range, azimuth, height, and elevation coordinates, respectively. 
 Asthesignal level increases, the output signal ofthis last stage reaches asaturation level Reference Ifechosignal[famplifier 1signal t !I Detector Detector Detector I t t t Video Video IVideo amplifler amplifier amplifier I I t Videooutputsignal FIG.16.29.—Circuit togivelin-log response, above which itcannot rise regardless offurther input-signal increases. Atthis point the output signal from the preceding stage has become appreciable; itcontinues toincrease with increasing input signal. NOW, however, theincrease inoutput-signal level isataslower rate because the gain ofthe last stage isnot available. 
 ch23.indd   34 12/20/07   2:21:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 
 I. Skolnik  (ed.), 2nd Ed., New York: McGraw-Hill, 1990. 154. 
 The filter bank (for  HBW = 17) is pictured in Figure 2.52 and the coefficients are shown in Table 2.3. FIGURE  2.50 Clutter input and residue from elliptic filter. Radar starts radiating at pulse  number 51.−100−90−80−70−60−50−40−30−20−100 0 20 40 60 8 0 100 Pulse NumberdBPoint Clutter Residue FIGURE  2.51 Effect of limiting on elliptic filter response−100−90−80−70−60−50−40−30−20−100 0 20 4 0 60 8 0 100 Pulse NumberdB Point clutter after i.f . 
 N. Radcliffe: Pulse Compression and Signal Processing, International Conjer-  ence on Radar-Present and Future, Oct. 23-25, 1073, pp. 
 TERN COULD BE SELECTED AND SHAPED ELECTRONICALLY -ORE AMBITIOUS READ hMASSIVE AND EXPENSIVEv  SYSTEMS TEND TO USE TWO 
 Hoft, D. J., and M. B. 
  DESIGN DUE  IN LARGE PART  TO THE PARTICIPATION BY KEY RADAR SPECIALISTS FROM #ANADAA MEMBER OF %3!S %ARTH /BSERVATION 0ROGRAM "OARDON THE !3!2 CONCEPTUAL DESIGN TEAM  4HE TRANSMIT AND RECEIVE POLARIZATIONS ARE INDEPENDENT OF EACH OTHER  SO THAT AT FULL RESOLUTION  THE POLARIZATION CHOICES ARE ((  66  OR (6 .OTE THAT THIS DUAL 
 SCANNED  ARRAY  AND D   "LASS 
 Queen: Dynamic Measurement of Radar Cross Sections, Proc. IEEE, vol. 53,  pp. 
 ERS "OTH SURFACES OF THE LENS REQUIRE MATCHING 4HE PRIMARY FEED SHOULD BE DESIGNED  WITH CARE AND CAN BE COMPLEX TO GIVE THE DESIRED APERTURE AMPLITUDE DISTRIBUTION WITH  LOW SPILLOVER LOSSES 4HE TRANSMITTER FEED CAN BE SEPARATED FROM THE RECEIVER FEED BY AN ANGLE @   AS SHOWN IN &IGURE  4HE PHASE SHIFTERS ARE THEN RESET  BETWEEN TRANS 
 The  signal received with the difference pattern provides the magnitude of the angle error. The sum  signal provides the range measurement and is also used as a reference to extract the sign of the  error signal. Signals received from the sum and the difference patterns are amplified separately  and combined in a phase~sensitive detector to produce the error-signal characteristic shown in  Fig. 
 TERING PLANES  FOR EXAMPLE  THE CORNER REFLECTOR  CAN CAUSE hBRIGHT SPOTSv IN THE IMAGE  AND VARIATIONS IN THE VELOCITY OF PROPAGATION CAN CAUSE DILATION OF THE ASPECT RATIO OF THE IMAGE !LTHOUGH MANY IMAGES CAN BE FOCUSED TO REDUCE THE EFFECT OF ANTENNA BEAM SPREADING  REGENERATION OF A GEOMETRIC MODEL IS A MUCH MORE COMPLEX PROCEDURE AND IS NOT USUALLY ATTEMPTED 4HE GENERAL OBJECTIVE OF SIGNAL PROCESSING AS APPLIED TO '02 IS TO PRESENT EITHER  AN IMAGE THAT CAN READILY BE INTERPRETED BY THE OPERATOR OR TO CLASSIFY THE TARGET RETURN WITH RESPECT TO A KNOWN TEST PROCEDURE OR TEMPLATE 4HE GENERAL PROCESSING PROBLEM ENCOUNTERED IN DEALING WITH '02 DATA IS IN THE  WIDEST SENSE THE EXTRACTION OF A LOCALIZED WAVELET FUNCTION FROM A TIME SERIES  WHICH DISPLAYS VERY SIMILAR TIME 
 A simplified version of the architecture results when the modu - lation is a binary phase code. In this case, the coefficients are either +1 or –1, so the  arithmetic performed for each sample is a complex sum or subtraction instead of   a full complex multiplication. Pulse compression may also be accomplished by operating in the frequency domain,  where it is referred to as fast convolution. 
 PULSE &)'52%  $ISTRIBUTION OF  ) AND MEAN OF  ) FOR HARD 
 The flip-flop returns spontaneously toits original state shortly before the start ofthe next radar cycle. Signals from switch b arecombined with range and angle marks inavideo mixer, from which they pass totransmitter No. 2. 
 AES-13, pp. 108-111, March 1977. 28. 
 II could also cause problems. Good results were also obtained on the ASV/BABS with horizontal aerials on the Wellington. A range of 16 miles on the equi-signal path was observed at 2000 ft. 
 Interference at the multiplexing frequency is, therefore, prevented from passing through the filters. The modulated difference channels are combined with the sum signal, and the . composite signal is processed in a single channel (just as a conical-scan signal). 
 OFF OF QUANTIZATION NOISE AND COM 
 1 RE, vol. 25. pp. 
 These may begrouped intime in. SEC. 8.9] TRAFFIC CAPACITY 265 different ways inorder togive vzmious groups inapparent range onthe indicator. 
 The suite of microwave and RF apertures in a fighter aircraft might appear as  shown in Figure 5.4. As many as 20 apertures may be distributed throughout the vehi - cle, performing radar, data link, navigation, missile warning, direction finding, jam - ming, or other functions over a frequency range covering several decades.2 There are  apertures distributed over the aircraft that point forward and aft, right and left, as well  as up and down. Some apertures will be shared for communications, radio navigation,  and identification (CNI) as well as identification, friend or foe (IFF) due to compatible  frequencies and geometries. 
 STEPPING THE INTRODUCTION OF THE APPROXIMATIONS REQUIRED BY THE ANALYTICAL SOLUTIONS DESCRIBED ABOVE )N SURFACE SCATTERING  PARTICULARLY FOR THE CONTINUOUS SEA SURFACE  THE METHOD OF CHOICE APPEARS TO BE SOME VARIANT OF THE -ETHOD OF -OMENTS  !N EXACT  INTEGRAL EQUATION FOR THE  SURFACE CURRENTS EXCITED BY AN ILLUMINATING FIELD IS SOLVED  NUMERICALLY OVER A GRID OF POINTS  WHERE THE FLEXIBILITY AND ACCURACY OF THE SOLUTION DEPENDS  ESSENTIALLY  ON THE GRID SPACING  THE SIZE OF THE SURFACE FEATURES COMPARED TO THE ILLUMINATING WAVELENGTH  THE EXTENT OF THE SURFACE OVER WHICH THE GRID IS LAID  AND THE EFFICIENCY OF THE COMPUTING ALGORITHMS USED IN WHAT ARE EXTENSIVE CALCULATIONS  /NCE FOUND FOR AN ENSEMBLE OF SURFACE REALIZATIONS  THESE CURRENTS CAN BE USED IN A  SCATTERING INTEGRAL OVER EACH OF THE SURFACES TO GENERATE AN ENSEMBLE OF  SCATTERED FIELDS   WHICH ARE FINALLY AVERAGED INTO A SURFACE SCATTERING CROSS SECTION  !LTHOUGH THESE  METHODS ARE OFTEN VIEWED AS THE hGOLD STANDARDv FOR DOING SCATTERING CALCULATIONS  THEIR COMPLEXITY AND DIFFICULTY GENERALLY RESTRICT THEIR APPLICATION TO IDEALIZED OR LABORATORY SURFACE STRUCTURES  WHERE THEY SIMPLY CONFIRM THAT -AXWELLS EQUATIONS CONTINUE TO BE VERIFIED IN SCATTERING EXPERIMENTS .EVERTHELESS  SUCH NUMERICAL SIMULATIONS CAN BE INFORMATIVE IN IDENTIFYING THE SOURCE OF PARTICULAR SCATTERING EVENTS  SUCH AS SEA SPIKES  ALONG WITH THEIR DEPENDENCE ON SUCH RADAR PARAMETERS AS GRAZING ANGLE  POLARIZATION  AND FREQUENCY   2OLE OF ,ABORATORY 3TUDIES  4HE SEA SURFACE IS A NATURAL SYSTEM CONTROLLED BY  THE LAWS OF HYDRODYNAMICS "UT SO IS A BOWL OF SOUP OR A TANK OF WATER OR A RUSHING STREAMALL OF WHICH MIGHT SHARE CERTAIN BEHAVIORS WITH A SEA SURFACE  WHILE PRE 
 Over a limited frequency band, delay is a linear function of frequency. The usable frequency band and the delay linearity are significantly improved by employing a tapered-waveguide structure. Since stripline all-pass networks are microwave counterparts of the low-frequency all- pass networks, the synthesis of these networks is usually based on the low- frequency approach. 
 16”36. The difference frequency of7(Ikc/see is obtained bymixing the power from two oscillators inacrystal rectifier. One ofthese oscillators can beareference standard against which the clOscillator under testj t Diffe~dtiator Crystal 70kc/sec— —Discriminator — frequencyRecti~lng mixer amplifier— weightingvoltmeter Jcircuit f, FIG. 
 Targets illuminated by the transmit beam outside the footprint are lost to the receiver. Four remedies to the beam scan-on-scan problem arc possible: (1) fix the transmit beam for the time required to complete a surveillance frame by the receive beam, step the transmit beam one beamwidth and complete a second surveillance frame, and so forth until the transmit beam has stepped across the surveillance sector; (2) scan the transmit beam and use multiple simultaneous receive beams to cover the surveillance sector; (3) scan the transmit beam and chase the transmitted pulse with the receiver beam; and (4) broaden the transmit beamwidth to floodlight the surveillance sector, and scan the receive beam across the surveillance sector. The first and fourth remedies require a dedicated transmitter; the second and third do not. 
 Averaging over time would result in a doppler shift tending to zero. Clearly, this is of  no value to the operator wishing to compensate for ionospheric motion and hence to  retrieve a meaningful estimate of target radial velocity. As a second example, consider  the situation where an atmospheric gravity wave (AGW) is propagating through the  ionosphere in the vicinity of the control point (ionospheric reflection point) while  a target is being tracked. 
 Knowing the shape of the antenna patterns, the measurement of the ratio of signals in  the two beams allows tlie target elevation angle to be deduced. A similar techniq~e~'.~' utilizes  sum (E) and difference (A) patterns whose ratio A/X is symmetrical. Just as in off-axis tracking,  the antenna boresight is locked at some elevation angle. 
  
 Figure 11. Resulting complex image after 10th additive summation of complex images: ( a) ISAR image amplitude; ( b) ISAR image phase. The ﬁnal complex image, amplitude and phase, obtained after additive Gaussian noise depression by coherent summation of 10 consecutive complex images of the asteroid is presented in Figure 11a,b. 
 Skolnik (ed.), McGraw­ Hill Rook Company. New York. 1970. 
 Since the target return must directly compete with the sidelobe clutter in the doppler resolution cell, it may be necessary to reduce the absolute amount of clutter contained in the cell. A positive signal-to-clutter ratio (SIQ is necessary to permit target visibility. One way to achieve this is to range-gate and thus reduce the size of the clutter patches, the return from which is accepted in the receiver. 
 D" BEAMWIDTH IN DEGREES 4HE CORRESPONDING ANTENNA GAIN  WHEN THE  BEAM POINTS BROADSIDE TO THE APERTURE  IS   ' y O .G y O .G,GA . 
 14. pp. 1584-1593. 
 Senior: Cross Polarization Diagnostics, IEEE Tram., vol. AP-20, pp.  223-224, March, 1972. 
 366-373, November, 1967.  64. Shrader, W. 
 LOBE LEVELS BUT EXCEED THE TIME SIDELOBE LEVELS ACHIEVED BY "ARKER CODES n LOG  .   ARE  TERMED MINIMUM PEAK SIDELOBE CODES 4HESE CODES ARE USUALLY FOUND USING COMPUTER  SEARCH TECHNIQUES 3KOLNIK AND ,EVANON AND -OZESON PROVIDE THESE CODES FOR VARIOUS  SEQUENCE LENGTHS  ALONG WITH THE RESULTING TIME SIDELOBE LEVELS #OMPLEMENTARY 3EQUENCES  #OMPLEMENTARY SEQUENCES CONSIST OF TWO SEQUENCES  OF THE SAME LENGTH  . WHOSE APERIODIC AUTOCORRELATION FUNCTIONS HAVE SIDELOBES EQUAL  IN MAGNITUDE BUT OPPOSITE IN SIGN 4HE SUM OF THE TWO AUTOCORRELATION FUNCTIONS HAS  A PEAK OF  . AND A SIDELOBE LEVEL OF  )N A PRACTICAL APPLICATION  THE TWO SEQUENCES  MUST BE SEPARATED IN TIME  FREQUENCY  OR POLARIZATION  WHICH RESULTS IN DECORRELATION OF RADAR RETURNS SO THAT COMPLETE SIDELOBE CANCELLATION MAY NOT OCCUR (ENCE  THEY HAVE NOT BEEN WIDELY USED IN PULSE COMPRESSION RADARS 0OLYPHASE #ODES  7AVEFORMS CONSISTING OF MORE THAN TWO PHASES MAY ALSO BE  USED 0OLYPHASE CODES CAN BE CONSIDERED AS COMPLEX SEQUENCES WHOSE ELEMENTS HAVE A MAGNITUDE OF ONE  BUT WITH VARIABLE PHASE  4HE PHASES OF THE SUBPULSES ALTERNATE  AMONG MULTIPLE VALUES RATHER THAN JUST THE  n AND n OF BINARY PHASE CODES 4HESE  CODES TEND TO BE DISCRETE APPROXIMATIONS TO ,&- WAVEFORMS  AND HENCE POSSESS SIMI 
 Although thefirstblindspeedisgreaterinatwo-frequency MTI,theremayhedeeper null~ thanonemightdesireinthedoppler response characteristic, justastherewouldbeina staggered MTIwithonlytwopulserepetition frequencies. Thetwo-frequency MTIhasthe advantage ofbeinglesssensitive thanasingle-frequency MTItoameanc1utter-doppkr­ frequency otherthandc,assuming thesingle-frequency MTIemploys nocompensation such asTACCAR. Thisalsoresults,however, inthelossofdetection oftargetswithlowdoppler­ frequency shiftthatotherwise wouldhavebeendetected withthesingle-frequency MTI. 
 BAND RADARS FOR SEVERE WEATHER AND TURBULENCE DETECTION AND AVOIDANCE  AIRBORNE RESEARCH RADARS MUST HAVE RELATIVELY MORE COMPLEX ARCHITECTURES  IN ORDER TO  MAKE MORE SENSITIVE  HIGH 
 12.4, accounting for refraction due to a uniform gra-  dient of refractivity  -2) . Tlie point of tangency of tlie line of sight with the earth is tlie geoint.tr.ical, or optical, /roi.i:ori.  At optical frequcticies (A 2 0) the field strength within the interference region (tliat is,  l~etwceti tlie radar arid tlie geometrical horizon) is essentially the same as in free space. 
 The radar transmitter may be operated continuously rather than pulsed if the strong  transmitted signal can be separated from the weak echo. The received-echo-signal power is  cotisicicrahly smaller than the transmitter power; it might be as little as 10- '' tllat of tllc  transmitted power-sometimes even less. Separate antennas for transmission and reception  help segregate the weak echo from the strong leakage signal, but the isolation is usually not  sufficient. 
 WAVE RADAR AT THE +WAJALEIN !TOLL v  )%%% !NTENNAS AND 0ROPAGATION -AGAZINE   VOL   NO   PP n  !PRIL   7 # +ELLOG  h$IGITAL PROCESSING RESCUES HARDWARE PHASE ERRORS v  -ICROWAVES  2&  PP n     .OVEMBER   # , 4EMES  h3IDELOBE SUPPRESSION IN A RANGE CHANNEL PULSE 
 S/N) for the waveform and select - ing a particular SNR of interest S/N0 along with its corresponding probability of  detection Pd,0. 2. Reduce S/N0 by a factor related to the relative output “power” of the matched  filter as a function of ambiguous range within the IPP. 
 The characteristic of a  saturated amplifier is that, above a certain level, the RF oiltput is independent of the RF inpiit.  A saturated amplifier is compatible with frequency and phase-modulated pulse compression  waveforms.  When tised in an amplifier chain, the CFA is generally found in only [lie one or two  highest-power stages. 
    
 Radio waves have characteristics common to other forms of wave motion such as ocean waves. Wave motion consists of a succession of crests andtroughs which follow one another at equal intervals and move along at aconstant speed. Like waves in the sea, radar waves have energy, frequency,amplitude, wavelength, and rate of travel. 
 The dotted portion of the curve reflects only the approximations formula (14.2). VT FIG. 14.2 Noise suppression by the correla- tion effect. 
 The justification for this definition is that the technology and design  philosophy of a multiple prf radar are more like that of an MTI than a pulse dopplcr.)  The pulse doppler radar is more likely to use range-gated doppler filter-banks than  delay-line cancelers. Also, a power amplifier such as a klystron is more likely to be used than a  power oscillator like the magnetron. A pulse doppler radar operates at a higher duty cycle  than does an MTI. 
 > ·.;:  0  41>  a:: -40 Main lobe  ~ Vestigial lobe or shoulder  ~1st side lobe  20 40 60 80 100 120  Degrees off axis 140 160 180  Fipre 7.1 Radiation pattern for a particular paraboloid reflector antenna illustrating the main beam and  the sidelobe radiation. (After Cutler et al.,3 Proc. IRE.) . 
 The necess ity of a down- converter is dete r- mined by the available A/D -converter. The digital output of each receiver channel is directly fed  to dedicated proce ssors. The processing modes are adapted to the transmit modes by downloa d- able software and they can be modif ied with changes in the sensor/target positions, the required  specifications in resolution, and the depth of processing. 
 SHIP NAVIGATION  AT LEAST UNTIL THEY CAN BE POSITIVELY IDENTIFIED  PERHAPS VISUALLY )F NO TARGETS ARE CORRELATED  IT SUG 
 354INTRODUCTION TORADAR SYSTEMS theneckoftheCRTtoprovideanaxialmagnetic field.Magnetic focusgenerally canprovide betterresolution, butthespottendstodefocusattheedgeofthetube. TheCRTdisplayisbynomeansideal.Itemploys arelatively largevacuum tubeandthe entiredisplayisoftenbigandcanbeexpensive. Thecostisnotsimplythetubeitself,whichis usuallymodest,butthevariouscircuitsneededtodisplaythedesiredinformation andprovide theoperator withflexibility. 
 BASED REFLECTORSCATTERING CODE BACKBONE 4HE CORE '/'4$ REFLECTORSCATTERING  &)'52%   4)#2! '2!30 '5)  MULTIBEAM ARRAY 
 Balaji, “Remote sensing of hail with dual linear polarization  radar,” J. Clim. Appl. 
 39•58•.59) This curve  is approximate since there is some slight dependence upon the false-a)arm probabiJity, but it  appears to oe independent or the signal-to-noise ratio. The actual value of m can differ  significantly from m.,r, without a large penalty in signal-to-noise ratio. For example. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 The radar frequency affects the low-frequency amplitude-noise spectrum shape  where the spectrum width is closely proportional to the radar frequency (if the target  span is assumed to be at least several wavelengths). 
 Ignoring the effect of target doppler, the required RF signal bandwidth is equal to  the transmitted waveform bandwidth. Given the RF signal bandwidth BR, the received  pulse width TR, and the range interval ∆T, the required LO reference waveform dura - tion is given by  T T TL R= + ∆ (6.4) the LO reference chirp waveform bandwidth is given by  BT T TBLR RR =+ ∆ (6.5) and the IF processing bandwidth is given by  BT TBI RR =∆ (6.6) 6.4 RECEIVER FRONT END Configuration.  The radar front end  consists of a low-noise amplifier (LNA) and  bandpass filter followed by a downconverter. 
 The Chinese remainder theorem is one means for calculating the true range from the several ambiguous measurements in a range-while-search system.38 This approach permits a unique direct computation of the true-range cell number R0 from the three ambiguous-range cell numbers A1, A2, and A3 (or two numbers for a two-PRF system). (The cell number is the range expressed in units of the pulse width and ranges from O to An1 - 1.) The theorem for a three-PRF system is ex- pressed by the congruence R0 (C1A1 + C2A2 + C3A3) (modulo An1An2An3) (17.6) The smallest value of Rc that satisfies Eq. (17.6) is the remainder of the term within parentheses when divided by An1An2An3 as many times as possible. 
 calculated23 and is summarized in Table 8.1. As can be seen, for a small number of reference cells the loss is large because of the poor estimate of a. Conse- quently, one would prefer to use a large number of reference cells. 
 For l)e.t fititsaxis must I)r ele]-:lte(l :Il)tlllt 1.00 al><)l-e the ll<)rizontal, Complltatiom SIIOIYC(I that, }}itlLantenna );-itlth Chown ataprdcti (al maximlnn and with all component. pll>hed to the limit in l]t’rforIll:lrl(t’, th(, (’overage a> sIIoIJ-11 inE“ig. 1!5.5 for thi. 
 Urkowitz and J. P. Nespor, “Obtaining spectral moments by discrete Fourier transform with  noise removal in radar meteorology,” Proc. 
 15.24 Improvement factor limitation due to scanning for cancelers with feedback, computer-calculated for an assumed antenna pattern of (sin U)IU terminated at the first nulls. without the use of feedback. The principal advantage of not using feedback is the excellent transient response of the canceler, an important consideration in a phased array or when pulse interference noise is present. 
 7.2 ANTENNA RADIATION PA ITERN AND APERTURE DISTRIBUTION  The electric-field intensity E(cp) p'roc:iuced by the radiation emitted from the antenna is a  function of the amplitude and the phase of the current distribution across the aperture. 1.4,5 E( cf>)  may be found by adding vectorially; Jhe contribution from the various current elements con­ stituting the aperture. The mathematical summation of all the contributions from the current  elements contained within the aperture gives· the field intensity in terms of an integral. 
 HORIZON RANGES WHEN THE TRANSMITTING ANTENNA IS LOCATED CLOSE TO SEA LEVEL  RATHER THAN IN AN ELEVATED POSITION PLACING THE ANTENNA EVEN JUST ONE OR TWO WAVELENGTHS ABOVE SEA LEVEL CAN INTRODUCE SEVERAL D" OF ADDITIONAL LOSS  u -OST (&372 SYSTEMS USE A VERY BROAD hFLOODLIGHTv TRANSMIT BEAM TO ILLUMINATE THE  ENTIRE COVERAGE ARC MULTIPLE SIMULTANEOUS RECEIVE BEAMS ARE FORMED TO FILL THE ARC  AND UPDATE ALL TRACKS SIMULTANEOUSLY 4HIS REDUCES COST AND COMPLEXITY BUT INCURS SOME LOSS OF SENSITIVITY FOR NOISE 
 Burrow, C. R.: Discussion on Paired Echo Distortion Analysis, Proc. IRE, vol. 
 MONOSTATIC GEOMETRY  WHICH REDUCES THE NUMBER OF REQUIRED BEAM STEPS 4HE  "ISTATIC 2ADAR FOR 7EAPONS ,OCATION TEST PROGRAM IS AN EXAMPLE &LOODLIGHT "EAMS  ! FLOODLIGHT BEAM CAN BE USED WITH EITHER TRANSMITTER OR  RECEIVER 4HE FLOODLIGHT TRANSMITTER REMEDY REQUIRES A DEDICATED TRANSMIT ANTENNA THAT IS DESIGNED TO FLOOD THE SURVEILLANCE SECTOR CONTINUOUSLY 4HE RECEIVER THEN SCANS THE SECTOR WITH A HIGH 
 The tracking radar attempts to position the  antenna to make the angular error zero. When the angular error is zero, the target is located  along the reference direction.  One method of obtaining the direction and the magnitude of the angular error in one  coordinate is by alternately switching the antenna beam between two positions (Fig. 
 OPTIMUM  NOT THE OPTIMUM 3ELECTING THE PREFERRED SOLUTION SHOULD BE BASED ON A WELL 
 48 INTRODUCTION TO RADAR SYSTEMS  0.99  0.98  0.95  0.90  ((' 0.80  C  ._g 0.70  u  ~ 0.60  OJ  'O .... 0.50  0  ro 'O 0.40  0.30  0.20  0.10  0.05  0.02  0.01  -10  -15  OJ  C  0  L  0 -10 .2  0  L  <lJ  <I)  0  C ' 0  ...--5  0  C 0,  <I)  0 c::  0 :;::  "O 0 "O  <{ -5 0 5 10 15 20  Signal-to-noise ratio per pulse, dB 25 Figure 2.22 Comparison of detec­ tion probabilities for five different  models of target fluctuation for  11 = 10 pulses integrated and  30 false-alarm number n1 108.  (Adapted from Swerling. 
 DENSITY CORES TO ATTAIN HIGH TRANSMISSION PERFORMANCE OVER LARGE  FREQUENCY BANDS $IELECTRIC ,AYERS WITH -ETAL )NCLUSIONS  -ETAL INCLUSIONS HAVE BEEN CONSIDERED  FOR USE WITH DIELECTRIC LAYERS TO ACHIEVE FREQUENCY FILTERING  BROAD 
 Chandler. R. A., and L. 
 737. CHAPTER 1 INTRODUCTION BYLOUIS N.RIDENOUR 101. What Radar Does. 
 18.18. These signals may then be processed as in a conventional amplitude- comparison monopulse receiver. The system shown in Fig. 
 Thedividing ofthe frequcncy bandintoNindependent partsbytheNfiltersalsoallowsameasure ofthedoppler frequency tobemade.Furthermore ifmovingclutter,suchasfrombirdsorweather, appears atother-than-zero frequency, thethreshold ofeachfiltermaybeindividually adjusted soasto adapttothcc1ullercontained withinit.Thisselectivity allowscluttertoberemoved which wouldbepassedbyadelay-line canceler. Thefirstsidelobe ofthefiltersdescribed byEq.(4.16) hasavalueof-13.2dBwithrespecttothepeakresponse ofthefilter.Ifthisistoohighfor propcrclutterrejection, itmaybereduced attheexpense ofwiderbandwidth byapplying amplitude weights Wi'Justasisdoneinantenna design,thefiltersidelobe canbereduced by usingChebyshev, Taylor, sin2x/x2,orotherweightings.39(Inthedigitalsignalprocessing literature, filterweighting iscalledwindowing.8oTwopopular formsofwindows arethe Hamming andhanning.) Itmaynotbeconvenient todisplaytheoutputsofallthedoppler filtcrsofthcfilterbank.Oneapproach istoconnect theoutputofthefilterstoagreatest-of circuitsothatonlyasingleoutputisobtained, thatofthelargestsignal.(Thefilteratdcwhich contains clutterwouldnotbeincluded.) theimprovement factorforeachofthe8filtersofan8-pulsefilterbankisshownin Fig.4.24asafunction ofthestandard deviation oftheclutterspectrum assuming thespectrum toherepresented bythegaussian function described byEq.(4.19).Theaverage improvement forallfiltersisindicated bythedottedcurve.Forcomparison, theimprovement factorforan N-pulsecanceler isshowninFig.4.25.Notethattheimprovement factorofatwo-pulse canceler isalmostasgoodasthatofthe8-pulsedoppler-filter bank.Thethree-pulse canceler is evenbetter.(Asmentioned previously, maximizing theaverage improvement factormightnot betheonlycriterion usedinjudging theeffectiveness ofMTIdoppler processors.) Ifatwo-orthree-pulse canceler iscascaded withadoppler-filter bank,betterclutter rejection isprovided. Figure4.26showstheimprovement factorforathree-pulse canceler and aneight-pulse filterbankincascade, asafunction oftheclutterspectral width.Theupper figureassumes uniform amplitude weighting (-13.2dBfirstsidelobe) andthelowerfigure showstheeITectofChebyshev weighting designed toproduce equalsidelobes withapeakvalue of-25dB.Itisfoundthatdoubling to16thenumber ofpulsesinthefilterbankdoesnot offersignificant "advantage overaneight-pulse filter.30Morepulsesdonotnecessarily mean moregaininsignal-to-c1utter ratio,becausethefilterwidthsandsidelobe levelschangerelative totheclutterspectrum asthenumberofpulses(andnumberoffilters)isvaried,Ifthesidelobes oftheindividual t!ltersofthedoppler filterbankcanbemadelowenough, theinclusion of thedelay-line canceler aheadofitmightnotbeneeded.. 
 130-134, 1985. 61. Dawson, C. 
 -AY 
 MADE CONTAMINANTS CAN  OF COURSE  HAVE THE SAME  EFFECT ! LAYER OF OIL ONLY ONE MOLECULE THICK WILL SIGNIFICANTLY AFFECT THE ABILITY OF THE SURFACE TO SUPPORT WAVE MOTIONS  BUT THIS LAYER MUST BE CONTINUOUS 4HE ADJA 
 This had a frequency range of 2500 –6900 Mc/s, with a nominal forward resistance of 265 Ω(ideally <200Ωbut up to 400 Ωwas considered satisfactory) and a forward –back ratio of about 8:1. These devices were extremely prone to damage from high RF ﬁelds, as discussed in chapter 4, section 4.7.1. The crystal mixer was fed from a ‘T’junction in the coaxial feed from the magnetron to the antenna and protected during transmission by a TR switch. 
 FREQUENCY DEVICES EXHIBIT HIGHER %P"A RATIOS AND TO OBTAIN A HIGH %P"A RATIO VERY FINE LINE GEOMETRIES ARE REQUIRED  WHERE THE TERM  GEOMETRY REFERS TO THE SURFACE CONSTRUCTION DETAILS OF THE  TRANSISTOR DICE 3ILICON  ,$-/3  &%4  4HE SILICON ,ATERALLY $IFFUSED -ETAL 
 Nathanson, Radar Design Principles , New York: McGraw-Hill, 1991, Fig. 2.2.  5. 
 SION ARE KNOWN AS '- AND %2-  RESPECTIVELY !S A SPACECRAFT  'EOSAT WAS ONE OF THE FEW %ARTH 
 BIT ADDER  SO THE -3" IS SIMPLY LOST  LEAVING US WITH A PHASE CODE OF   O   WHICH IS THE SAME AS O 4HEREFORE  THE RESULTING PHASE WAVEFORM TAKES ON A  SAWTOOTH PATTERN  LINEARLY RAMPING FROM O TO NOT QUITE O AND THEN RESETTING TO O  AND RAMPING AGAIN !N IMPORTANT FEATURE OF AN .#/ FOR A RADAR APPLICATION IS THE #,%!2 SIGNAL SHOWN  GOING TO THE PHASE ACCUMULATOR REGISTER &OR A COHERENT RADAR EXCITER IMPLEMENTA 
 (From Moore et al., University of Kansas Remote Sensing Laboratory Technical Report 243- 12, /975.) RESOLUTION (m) FIG. 12.28 90 percent range of pixel amplitude versus resolution.FREQUENCY(GHz): 13.9 POLARIZATION: VV UPPER DECILE, (^0 LOWER DECILE, a^ MEAN, a°NUMBER OF SAMPLES FOR EACH DATA POINT95%-5% SPREAD (dB) . with averages over different-sized footprints. 
 POINT &&4 TO FORM HIGHLY OVERLAPPED DOPPLER FILTERS&)'52%  #OMPARISON OF DETECTION PERFORMANCE WITH AND WITHOUT ECLIPSING AND RANGE GATE  STRADDLE LOSS 4HE APPROXIMATE PERFORMANCE USING %Q  IS ALSO PROVIDED 4HE PERFORMANCE WITH  ECLIPSING AND RANGE GATE STRADDLE LOSS WITH THE USE OF  OVERLAPPED RANGE GATES IS SHOWN   &327     '   /&* #0%3,!#0)'2       0.$#$*+*27.('2'%2*.-   
 Geographic relationship of ALOS-2 scene, EIELSON station, and Poker ISR station. 4. Results and Discussions 4.1. 
 Forpractical utilization, mostofthetargetJclassification methods described aboverequireautomatic processing. Somemethodofsignalrecognition or patternrecognition mustbeappliedtobeabletocorrectly estimate thetypeoftarget.Thiscan bejustasimportant apartoftargetclassification asthesensoritself. Targettrackhistory.Theabovemethods oftargetclassification dependonextracting some­ thingaboutthetargetotherthanitslocation. 
 A book on microwave power sources4 suggests that these devices be called microwave vacuum electronic  devices (MVED) . In this chapter, however, the name tube will be retained. ch10.indd   2 12/17/07   2:19:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Note that only a single value is given even though there can be a large variation.  They should not be used for design purposes when actual data is available for the particular  targets of interest.  A military propeller aircraft such as the AD-48 has a cross section of about 20 m2 at L  band, but a 100 m2 cross section at VHF. 
 i111d P. 1. Pccljlcs. 
 D. Kieu, “Effect of tall structures on microwave communication systems,” M.S. thesis, University  of Kansas, Lawrence, 1988. 
 The first experimental radar systems operated with CW and depended for detection upon  the interference produced between the direct signal received from the transmitter and the  doppler-rrequency-shifted signal reflected by a moving target. This effect is the same as the  rhythmic flickering, or flutter, observed in an ordinary television receiver, especially on weak  stations, when an aircraft passes overhead. This type of radar originally was called CW  wave-interference radar. 
 3.6) spaced throughout the frequency  range permits a measurement of frequency and improves the signal-to~noise ratio. The . CW AND FREQUENCY-MODULATED RADAR 77  1 Filter No. 
        4HE 0 AND 0 CODES ARE DERIVED BY ESSENTIALLY CONVERTING AN ,&- WAVEFORM TO  BASEBAND 4HESE TEND TO BE MORE DOPPLER TOLERANT THAN THE &RANK  0  OR 0 CODES   AND ARE ALSO MORE TOLERANT OF PRECOMPRESSION BANDWIDTH LIMITATIONS THAT APPEAR IN RADAR SYSTEMS 4HE PHASE OF THE 0 CODE IS GIVEN AS   JP N.N     N    x . n   4HE 0 CODE PHASE RELATIONSHIP IS SIMILAR   FPPNN .K 
 S.4.—The AN/CPN-6 beacon. The .4N/CPN-6 isahi..zh-nowered 3-cm beacon 2,interided foruseinpermanent iristallations onth~g~ound. Special systems designed formeasuring with great accuracy the ranges from two ground beacons atknown positions have been used formapping and blind bombing ofhigh precision. 
 For the great majority of systems the CRT  is the ‘eye,’ and is the equivalent of the loud-speaker in  the normal broadcast-receiver chain. Whereas the loud-  speaker is called upon to handle a range of low fre-  quencies and harmonics, all between about 50 and 10,000  cycles per second, the displays on the CRT screen are  varied and complex. The CRT and its application to  radar is thus a complete story in itself. 
 Figure 8.1 shows a block diagram of a basic pulse compression radar. The coded  pulse is generated at a low power level in the waveform generator and amplified to the  required peak transmit power using a power amplifier transmitter. The received signal  is mixed to an intermediate frequency (IF) and amplified by the IF amplifier. 
 DOPPLER COUPLING FOR A NONSYMMETRICAL .,&- WAVEFORM #OMMON  THEREFORE  IN !4# RADARS -ULTIPLE TUNED PULSE COMPRESSORS REQUIRED FOR HIGH 
 Stuckey, “Cascaded spatial correlation processes for dense  contact environments,” in Proc. RADAR 1987 , 1987, pp. 125–129. 
 TIME ESTIMATION OF  - AND 2 AND TO THE INVERSION OF  - 3EVERAL PROCESSING . Ó{°£È  2!$!2 (!.$"//+  SCHEMES HAVE BEEN CONCEIVED THAT MAY BE CLASSIFIED IN TWO MAIN CATEGORIES   CLOSED 
 The PRI and duty cycle set the maximum  allowed time for a return echo, while the power or energy  transmitted must overcome the background noise to be  detected by  the receiver.   Pulse width also affects a radar’s minimum resolution. Echoes  from long pulses can overlap in time, making it impossible to  determine the nature of the target or targets. 
 22 of" Radar Handbook," M. I. Skolnik (ed.). 
 l3  The following conclusions apply to the continuous antenna:  1. According to R~tze,''~ the spurious sidelobe radiation is proportional to the mean square  error, just as in the discrete array, and in addition is proportional to the square of the  correlation interval measured in wavelengths. Bates' " defines his correlation interval dif-  ferently from Ruze and obtains a first-power dependence for this reason. 
 Envir. , vol. 81, pp. 
 However, there can be large differences in level at other locations on the earth. Other effects that can control radar performance are sometimes mistaken for the passive noise discussed above. One of these is the spread-in-doppler clutter from localized high-density irregularities in sky ionization; this is sometimes refered to as active or multiplicative noise. 
 November.  1954.  57. 
 The  LFM waveform has a swept bandwidth B, pulsewidth T, and LFM slope α. The refer - ence waveform is generated with time delay tR, swept bandwidth BR, pulsewidth TR,  and LFM slope aR. The reference waveform time delay is typically derived by range  tracking of a selected target within the range window. 
 Intheinverted coaxialmagnetron thecathodesurrounds theanode.Thestabilizing TEo!! cavityisinthecenterofthemagnetron withavane-type resonator systemarranged onthe outside.Thecathode isbuiltasaringsurrounding theanode.Poweriscoupledfromtheendof thecentralstabilizing cavitybyacircular waveguide. Thegeometry oftheinverted coaxial magnetron makesitsuitable foroperation atthehigherfrequencies. Figure6.5isanexample. 
 Insome cases, the gain isnot worth the price and thesimpler c-w system isadequate. Finally, there are some things which pulse-type systems simply cannot dfiwork down tozero range, forexample. Inthe descriptions ofc-w systems tofollow, they will bepresented roughly inthe order oftheir complexity astoobjects, conception, and apparatus. 
 Thus, the experimental results prove the capability of target discrimination in this X-band CSAR data and scene. 260. Sensors 2019 ,19, 346 5. 
 The switch iscontrolled byaflopover circuit (Fig. 13.16) which remains inthe stable state that causes video switch a topass theradar signals until abeacon switch-pulse occurs; itthen passes toasecond stable state that causes the video switch topass beacon signals. Atthe next modulator pulse the original condition isrestored. 
 *OINT AIRCRAFT AND SHIP DETECTION  TWO 
 24, 1983. 10. Ulsamer, E.: In Focus—Approach Set on Space Radars, Air Force Mag., vol. 
 SEA CLUTTER  15.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 Since the phases of these waves are lost, the spectrum gives no information about the  detailed morphology of the surface itself, i.e., about the complex surface features that  are responsible for the scattered field. This point will be raised again as we go along. General Sea Descriptors. 
 Cloude and E. Pottier, “An entropy based classification scheme for land applications of  polarimetric SAR,” IEEE Trans. Geoscience and Remote Sensing , vol. 
 MUTH RESOLUTION 4HE DOPPLER BANDWIDTH OF THE ORIGINAL SIGNAL HISTORY FROM A GIVEN BACKSCATTERER MAY BE REDUCED BY THE SIMPLE EXPEDIENT OF GENERATING A SHORTER SYN 
 Ward, H. R.: Dispersive Constant False Alarm Rate Receiver, Proc. IEEE, vol. 
 This means that the signal probably penetrated to the ground surface at frequencies below about 6 GHz. Nevertheless, the model indicates the kind of results to be expected for this im- portant situation. Table 12.3 gives the resulting constants to use in Eq. 
 WAVE STRUCTURE  THE 2& SIGNAL IS SLOWED DOWN BY THE HELIX SO THAT ITS FORWARD VELOCITY IS VERY NEARLY EQUAL TO THAT OF THE VELOCITY OF THE ELECTRON BEAM 4HIS NEAR MATCH OF VELOCITIES IS WHAT CAUSES THE CUMULATIVE INTERAC 
 176 THEGATHERING ANDPRESENTATION OFRADAR DATA [SEC..69 reporting system forthegreater part ofthewar. Atthevery end ofthe war the system was used toplot V-2 rockets. The great success ofthe equipment, which saved the country from defeat during the Battle of Britain, had animportant effect onthecourse ofradar development. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 4.8 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 offset applied to the transmit frequency. 
 Aklystron canbeoperated overafairlywiderangeofbeamvoltagewithout alarge changeinthegaincharacteristics. However, high-power traveling-wave tubestendtooscillate atreduced beamvoltage. Therefore thetolerance ontheTWTbeamvoltagemustbetighter withincreasing bandwidth. 
 284–290. 158. P. 
 This type ofline isrelatively easy tomake. The two end surfaces of the main assembly are ground flat and parallel after welding. The tolerance inparallelism iseased forthe critical signal line bythe auto- collimating effect ofthethree reflector blocks. 
 Chaplin: Drives for Steerable Antennas. Hydraulics versus Elcctro­ Mechanics, "Oesign and Construction of Large Steera.ble Aerials," I EE (London) Conference P11hli­ catio11110. 21, pp. 
 A much wider class of antenna is available for use by the designer of frequency  domain radars. The noise floor of the receiver is much lower than the time-domain  equivalent, simply by virtue of its lower bandwidth and hence lower thermal noise.  Typically, a sensitivity of –120 dBm is found and a system peak transmitted signal  to mean receiver noise range of 180 dB is feasible. 
 L.: Radar in the Signal Corps, IRE Trans., vol. MIL-4, pp. 555-561, October, 1960. 
 12, G. L. Geernaert and W. 
 Kressman: First Bistatic Oblique Incidence Ionograms Be- tween Digital Ionosondes, Radio Sd., vol. 18, pp. 608-614, July-August 1983. 
 Thebranch-type duplexer, diagrammed inFig.9.5wasoneofthe earliestduplexer configurations employed. ItconsistsofaTR(transmit-receive) switchandan ATR(anti-transmit receive)switch,bothofwhicharegas-discharge tubes.Whenthetransmit­ teristurnedon,theTRandtheATRtubesionize;thatis,theybreakdown,orfire.TheTRin thefiredcondition actsasashortcircuittoprevent transmitter powerfromentering the receiver. SincetheTRislocatedaquarter wavelength fromthemaintransmission line,it appears asashortcircuitatthereceiverbutasanopencircuitatthetransmission linesothat itdoesnotimpedetheflowoftransmitter power.SincetheATRisdisplaced aquarter wavelength fromthemaintransmission line,theshortcircuititproduces duringthefired condition appears asanopencircuitonthetransmission lineandthushasnoeffecton transmission. 
 >-0difficulty ~vas exp~rienced inmain- taining thistolcranrc ~~-ith a25-ft reflector, butthetolerance problem Ivas foun(l tobesf’~-ere for an experimental 50-ft reflector con- ~tr[lctcd for aparticular application. These experience+ WOU1(l indicate that an antenna \ridth uptoabout 35ftmight lwdc>iral>le. Ifa~v:-i~-elength inthe region from 8.0cmto 8..5cm~~-cre u,efl ~\-ith >l~ch anantenna, thebeamlfidth should beabout 0,55°, \\-hich appear> tolx’about thepractical minimum. 
 H. Ganton, and J.  Mitchell: A Lightweight and Self-contained Airborne Navigational System, Proc. 
 182 INTRODUCTION TO RADAR SYSTEMS  resolution isolates the individual scattering centers and therefore eliminates the glint problem.  With aircraft targets an effective pulse width of several nanoseconds (kss than a meter rangc­ resolution) can resolve the individual scatterers. Once the scatterers are resolvt!d in range, an  angle measurement can be obtained on each one by use of monopulsc. 
 Rept.  4888. Mar. 
 MUM REFLECTIVITY VALUES OF n D": OR LESS AT SHORT RANGES EG   KM  /PERATIONAL RADARS IN THE PAST HAVE EMPLOYED SENSITIVITY TIME CONTROL 34#  TO  REDUCE GAIN AT SHORT RANGE AND COMPENSATE FOR STRONG NEARBY ECHOES HOWEVER  RECENT RADARS TEND NOT TO USE 34# TECHNIQUES SINCE RECEIVER DYNAMIC RANGES ARE ADEQUATE TO COVER IMPORTANT WEATHER ECHO INTENSITIES AT THE NECESSARY RANGES 2ESEARCH RADARS HAVE RARELY USED 34# OWING TO THE ATTENDANT LOSS OF SENSITIVITY AT SHORT RANGES £°ÎÊ 
     "!$ !  #&   - #*   "!$ !  #&   - #*  ##'&**!#  !+* (, % *  !+.!$# % +  (, % *,$ )&  (, % * 
 This is the basic method of navigation which in its  British form is known as Gee—a code word which  seems destined to live; using longer wavelengths, the  . SBLEWUARUNIC NAVAIUVALLILUN i4gy  system has been developed by American scientists, and  is there known as Loran, an abbreviation of ‘long-range  navigation.” The Loran system has the advantage over  Gee in that its pulses, on longer wavelengths, are propa-  gated over wide stretches of the earth’s surface by  multiple reflection from the ionosphere, but it suffers  from the disadvantage of all other reflected propagations  in that path-lengths are not precisely determinate, and  the errors of position-finding are in consequence usually  somewhat greater. Loran enthusiasts claim that although  its daytime ground waves cover about 500 to 700 miles,  which is not much more than with Gee, the night-time  sky waves extend coverage up to some 1400 miles. 
 BEAM ANTENNAS MOUNTED IN THE TAIL OF THE 0 
 CATES THAT THE AVERAGE POWER IS FAR MORE IMPORTANT THAN THE PEAK POWER AS A MEASURE #HAPTER . £ä°Ó  2!$!2 (!.$"//+  OF THE RADARS CAPABILITY ! VACUUM TUBE   WITH A GIVEN AVERAGE POWER CAN USUALLY BE  DESIGNED TO HANDLE THE HIGH VOLTAGES ASSOCIATED WITH A LARGE PEAK POWER WITHOUT BREAK 
 13 to 1.14 hole, in propagation, 26.9 information from, 1.7 to 1.10 letter-band nomenclature, 1.13 to 1.14 multifunction, for fighter aircraft, 5.1 to 5.10 networked, 7.46 to 7.49 nomenclature, 1.18 to 1.19 oceanography at HF, 20.30 to 20.38 past advances in, 1.19 to 1.20 reflectivity, 19.3 reflectivity factor, Z, 19.4 scheduling and control, 7.46 types of,  1.5 to 1.7 warning receiver (RWR), 24.4 to 24.5 work station, 24. 55 to 24.56 RADARS AT, 18.9 to 18.10 Radial velocity, 1.7 Radiating elements, 13.5 to 13.6 Radomes, 12.39 to 12.41 Radome loss, 4.40 Rain, attenuation by, 19.8 to 19.11 Rain, detection of, 19.3 to 19.6 RAMP air traffic control radar, 11.33 to 11.34 Range, as used in radar, 1.2, 1.7 Range ambiguities, in meteorological radar, 19.12 to 19.13 ambiguity resolution in pulse doppler, 4.31 to 4.33 and doppler, in MFAR, 5. 7 to 5.8 error, in tracking radar, 9.43 to 9.44 filter map in sidelobe blanking, 24.13 to 24.14 -gate pull-off, 24.6, 24.44 -gate straddle loss, 4.40 to 4.43 -gated high PRF (RGHPRF), 5.20 to 5.22 gates, 4.2 g ating in pulse doppler, 4.9 glint, 9.35 to 9.36, 9.47 noise, 9.35 to 9.36 sidelobes, 6.29 tracking, 9.21 to 9.24 Rank detector, 7.17 Rapid Doppler on Wheels (Rapid-DOW) 19.36 to 19.37 Ratio detector, 7.13 to 7.14 Rayleigh region, 14.5, 19.3 to 19.4 Rayleigh scattering, 14.19 to 14.20 Ray tracing, 20.20 to 20.21 Receiver, 1.3 analog-to-digital converter, 6.35 to 6.40 bandwidth, 6.9 channel matching, 6.29 COHO, 6.20 configuration of, 6.1 to 6.4 digital, 6.40 to 6.46 diplex operation, 6.46 to 6.47 dynamic range, 6.4 to 6.8. 
 BASED RADAR IS CONSIDERABLY MORE CHALLENGING THAN FROM A SURFACE 
 Wen, D.; Yuan, Y.; Ou, J.; Zhang, K. Ionospheric response to the geomagnetic storm on August 21, 2003 over China using GNSS-based tomographic technique. IEEE T rans. 
 This is sometimes called a mixer-macrix  feed.  A convenient method for achieving two-dimensional scanning is to use frequency scan in  one angular coordinate and phase shifters to scan in the orthogonal angular coordinate, as was  diagrammed in Fig. 8.18. 
 $    4HE POLARIMETRIC PRECIPITATION MEASUREMENTS BRING UNIQUE CHARACTERISTICS THAT  ADDRESS NOT ONLY IMPROVED PRECIPITATION MEASUREMENTS  BUT ALSO  IMPROVED DATA QUAL 
  
 Another way ofreducing theamount ofdroop onthepulse isbyusing low-frequency compensation circuits. InFig. 12”10, ifR,and C’. 
 87, pp. 1503–1521, 2006. 137. 
 NAL INTO TYPICALLY ^  RANGE BINS   n  BEAMS  AND ^ DOPPLER CELLS  IN PERHAPS  ^ SECONDS  USING GENERAL PURPOSE COMPUTING HARDWARE 4HUS  THE && 4 OR $&4 FOR  SHORT TRANSFORMS  IS COMMONLY USED FOR THE THREE DIMENSIONS OF ANALYSIS !LTERNATIVE ANALYSIS TECHNIQUES HAVE BEEN IMPLEMENTED IN SOME SYSTEMS FOR APPLICATIONS SUCH AS DETECTION OF ACCELERATING TARGETS  n THE DETECTION OF HARMONICALLY RELATED SIGNALS   AND WHEN HIGH DOPPLER RESOLUTION IS REQUIRED BUT ONLY SHORT COHERENT INTEGRATION TIMES CAN BE ACCOMMODATED IN THE RADAR TIMELINE  3OME IMPORTANT PROCESSOR DESIGN CONSIDERATIONS EMERGE FROM AN ANALYSIS OF  HIGH QUALITY (& RADAR DATA  AS ILLUSTRATED BY THE FOLLOWING EXAMPLE &IGURE  SHOWS A SEQUENCE OF SEA CLUTTER DOPPLER SPECTRA FROM THE !.&03 
 Ifthis isthesine pulse, thesequence is established. Ifitisnot, thecosine-pulse switch will pass no.signal, and the process must start over. Inpractice, the right combination is promptly found, and thevarious pulses then pass through thesequencing circuits intheproper manner. 
 JO  F,/T      ;LINE = COSO  F,/T      nJ;LINE = SINO  F,/T       ;)      J1=  &)'52%   4YPICAL ANALOG DOWNCONVERSION TO BASEBAND  AND DIGITIZER 
 Suchconformal arrayshave beenconsidered forradarbuttheydonotappearsuitable forgeneralapplication. Theyhave alsobeenexamined forIFFandairtrafficcontrolinterrogation antennas.132 Aseriouscompetitor tothecylindrical arrayisanumber ofplanararraysarranged to approximate thecylinder. Thisisamuchsimplersystemandisquitepractical. 
 High availability also requires that  spare parts be at hand when needed and that maintenance personnel be experienced and  motivated. In diplex operation the two frequencies are radiated on orthogonal polarizations.  Frequency and polarization diversity can provide an improved signal-to-noise ratio by con­ verting a Swerling type 1 target (Sec. 
 BASED SYSTEMS !LSO  COMPARED WITH EARLIER YEARS  WHEN RACONS WERE ESSENTIAL  MANY MORE NAVIGATIONAL AIDS ARE BECOMING AVAILABLE THAT ASSIST POSITIONING 4HESE INCLUDE MULTIPLE '.33 SERVICES  DIFFERENTIAL '.33  !)3  AND ENHANCED 643 FACILITIES 4HERE ARE ALSO GREAT IMPROVEMENTS  IN ONBOARD NAVIGA 
 Typically, in terms of target span along  the range coordinate, the rms value will fall between 0.1 and 0.3 times the target  span—being close to the multiplier, 0.3, for the tail view and nose view, and 0.1, for  the side view. The spectral shape may be closely estimated by using the same function  of frequency as described for angle noise and the same value of bandwidth. The error  as a function of relative phase and amplitude of the target reflectors is similar to the  angle noise phenomenon. 
 It can be clearly seen that the spatial variations of the Doppler rate and the derivative of the Doppler rate are about 8Hz/s and 0.08 Hz3, respectively. Figure 7a,b shows the spatially-variant phase errors caused by the spatially-variant Doppler parameters, which are about 100 rad (larger thanπ 4) and 4 rad (larger thanπ 8), respectively. If the phase error caused by the Doppler rate is larger thanπ 4, or the phase error caused by the derivative of the Doppler rate is larger thanπ 8, it will seriously degrade the image quality. 
 CO~fIROl. ...... APG. 
 For rotating scanning ArcSAR, even if targets in scenes have the same range and Doppler with antenna, if the heights of targets are di ﬀerent, their range migration will be di ﬀerent. Traditional ArcSAR imaging algorithms achieve imaging on reference plane. The height di ﬀerence between reference plane and target in scenes will cause the decrease of imaging quality or even image defocusing because the range migration cannot be compensated correctly. 
 Let F,, GI be  the noise figure arid available gain, respectively, of the first network, and F,, G, be similar  pararneters for the second network. The problem is to find F,, the overall noise-figure of the  two circuits in cascade. From the definition of noise figure [Eq. 
 Atypicalradarmighthaveaheam­ widthofperhapsoneortwodegrees. Theangular resolution isdetermined bythebeamwidth, buttheangularaccuracy canbeconsiderably betterthanthebeamwidth. Atentooneheam splitting wouldnotbeunusual foratypicalradar.Someradarscanmeasure angular accuracy considerably betterthanthis.Anrmserrorof0.1mradispossible withthebesttracking radars. 
 SAR processing needs phase coherence for obtaining the syn - thetic aperture, thus frequency agility has to be used with care. Frequency chang - ing during a synthetic aperture length time results in a change of focal length  (different coefficient of the quadratic phase term) of the phase history of the illu - minated targets that degrades the cross-range resolution. SAR operating in burst  mode can change its central frequency from one look to another, without any  degradation in image quality. 
 21-23,1975,pp.221-225. 83.White,W.D.:Circular Polarization CutsRainClutter,Electronics, vol.27.pp.158-160, March. 1954. 
 ESSAf\,follogral'h I.1966. 17.Bean.B.R..andG.D.Thayer: ModelsorAtmospheric RadioRefractive Index.Proc.IRE.vol.47. pp.740755.May.1959. 
 (19) d=(2p– 1):. Thus forcancellation the phase change must berand thelayer anodd multiple ofaquarter wavelength thick. The minimum reflection will actually beOif g=lnl~~, a Mid since gn gn~.—. 
 T. Coate:" Principles of Radar," Chap. J, McGraw-Hill Book Company, New  York. 
   &&"  &  ! $"%%"$ 
 Practical considerations often limit the SLC nulling capabilities to JCR of about 20 to 30 dB, but their theoretical performance is potentially much higher.30'31 Examples of possible limitations are listed below: 1. Mismatch between the main and auxiliary signals including the propagation paths, the patterns of the main and auxiliary antennas, the paths internal to the system up to the cancellation point, and the crosstalk between the channels.32'33 2. The limited number of auxiliary channels adopted in a practical system as compared with the number of jamming signals.32 3. 
 Inbeacon operation, power istransferred from the search local oscillator tothebeacon local oscillator, which (asdescribed inSec. 12.7) iscoupled tothe receiver crystal and toareference cavity tuned toa frequency 30Me/see below the beacon frequency. Asmall 1000-cycle sinusoidal modulation, supplied byoscillator VE,issuperimposed onthe sawtooth applied tothe reflector. 
 24.42  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 system to simultaneously track both the skin and false-target returns. This approach  utilizes the fact that both the jamming signals and the target return come from the  same angular direction, so that the radar’s angle-tracking circuits are always locked  onto the real target.3 The methodology of introducing VGPO into the radar’s tracking circuits is analogous  to the method used with RGPO. The frequency shift is initially programmed so that the  repeated signal is within the passband of the doppler filter containing the target return. 
 theradarapplications inwhi-chJld-yantage canbe.taken ofthelargeforward-scatter signalare limited.Thescattering anglepmustbeexactly,orreasonably closeto,180°inordertoobtain forwardscatter.Therefore thetargetmustliealongthelinejoiningthetransmitter andreceiver. Thusthetransmitting andreceiving antennas mustbewithinlineofsightofeachotheror nearlyso.(Theforward-scatter beamwidthfromasphereofradiusaisapproximately Ulna. whena/A.~1.6°) Another consequence ofabistaticradardesigned totakeadvantage ofthelargeforward­ scattercrosssectionisthelossofdopplerandtarget-position information. 
 'l'lie null spacing is also relatively insensitive to the cone half-angle. If a  "typical" value of cross section is taken as 0.1A2, the cross section at S band (A = 0.1 m) is  10 hi2, and at ,I' band (A = 3 cm), the cross section is approximately mZ. Thus, in  theory. 
 A. Marki: Thin-Film Mixers Team Up To Block Out Image Noise, hfrcro-  waves, vol. 11, pp. 
 322-329, Washington, 1985. 58. Hsu, Y. 
 8,1943; alsoWar Department Technical Manual TM 11-1566.. 296 ANTENNAS, SCANNERS, AND STABILIZATION [SEC. 9.14 tobedescribed was developed forthe 3-cm band toprovide coastal defense batteries with accurate target position and “splash-spotting” data forfire control. 
 Steenson, “Radar methods for the exploration of glaciers,” Ph.D. dissertation, Calif. Inst. 
 Any use is subject to the Terms of Use as given at the website. Pulse Compression Radar. 8.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 8.4 PULSE COMPRESSION IMPLEMENTATION  AND RADAR SYSTEM EXAMPLES This section describes the generation and processing of pulse compression waveforms  and provides examples of radar systems that utilize these processing techniques. Major  advances are continually being made in the devices and techniques used in pulse com - pression radars. 
 The larger the size of the target the  narrower will be the lobes and the greater will be the fluctuation frequency for a given angular  rate of change of aspect. In principle, the cross-section fluctuations might be able to provide  some information that can distinguish one type of target from another. If the target is rotating,  as were some of the early unstabilized satellites, the amplitude fluctuations of the radar cross  section with time can provide information from which the shape of the target can be  determined.60 It has also been suggested that the complex echo-signal fluctuations (amplitude . 
 A bank of narrowband filters may be used after the detector in the video of the simple CW  radar of Fig. 3.2 instead of in the IF. The improvement in signal-to-noise ratio with a video  filter bank is not as good as can be obtained with an IF filter bank, but the ability to measure  the magnitude of doppler frequency is still preserved. 
 21 Basic block diagram of an FM-CW range-discriminating scatterometer: control and  data-handling system ch16.indd   28 12/19/07   4:55:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 TRAL ENERGY AT THE DOPPLER FREQUENCIES EXPECTED FROM MOVING TARGETS  THIS UNWANTED NOISE OR SPECTRA WILL DEGRADE THE DETECTION OF DESIRED TARGETS 4HE TRANSMITTER NOISE IS REFLECTED BACK FROM THE CLUTTER AND ENTERS THE RECEIVER AND IS SOMETIMES CALLED hTRANSMITTED CLUTTERv  3OME TYPES OF MICROWAVE TUBES ARE MORE OF A PROBLEM THAN  OTHERS %XTRANEOUS NOISE IN A MICROWAVE AMPLIFIER TUBE AT THE FREQUENCIES EXPECTED FROM DOPPLER 
 MEDIUM  02& WAVEFORMS  2ANGE GHOSTS OCCUR IF THE CORRELATED RANGE DOES NOT REPRESENT THE TRUE TARGET RANGE AND TYPICALLY OCCUR WHEN THERE IS MORE THAN ONE DETECTION PER LOOK 2ANGE GHOSTS CAN ALSO OCCUR IF A TARGET DETECTION ON A SINGLE LOOK CORRELATED WITH OTHER DISSIMILAR TARGETS   OR IF MULTIPLE RANGE CORRELATIONS OCCURRED ON A SET OF DETECTIONS CORRESPONDING TO A SINGLE UNIQUE TARGET IE  MULTIPLE UNFOLDED RANGES FELL WITHIN THE CORRELATION WINDOW  /NE METHOD FOR EFFICIENTLY SCANNING AND CORRELATING THE UNFOLDED DETECTIONS  INVOLVES  COARSE BINNING  AS SHOWN IN &IGURE  (ERE  AMBIGUOUS DETECTIONS ARE  FIRST AMPLITUDE CENTROIDED AND THEN UNFOLDED  AS DISCUSSED PREVIOUSLY  BUT WITH THE RESULTS STORED IN AN ARRAY WHOSE ELEMENTS ARE THE COARSE BINS 4HESE BINS HAVE A SIZE LESS THAN OR EQUAL TO THE SHORTEST )00  AND CORRELATION INVOLVES SCANNING IDENTICAL BINS ACROSS ALL OF THE 02&S IN THE DWELL AND APPLYING A CORRELATION WINDOW )N THE EXAMPLE SHOWN IN &IGURE   THE BINS ARE SET TO NINE RANGE GATES SHORTEST )00 LENGTH   AND THE FIFTH COARSE BIN CONTAINS DETECTIONS ACROSS THE THREE 02&S THAT FALL WITHIN THE CORRELA 
 # BIASED TRANSISTOR IS PULSED  IT PASSES THROUGH ITS CUTOFF  LINEAR  AND SATURATION REGIONS #ONSEQUENTLY  THE INPUT AND OUTPUT IMPEDANCES ARE DYNAMICALLY VARYING  AND THE INPUT IMPEDANCE CHANGES VERY DRAMATICALLY 4HE DRAMATICALLY CHANGING INPUT IMPED 
 LEVEL  OBJECTIVES OF THIS EXPERIMENT WERE   TO PROVIDE THE NEAR 
 CAL BEAM LOCATIONS  AND   THE EFFICIENCY OF UTILIZING SPACE COMBINING INSTEAD OF PERFORMING THE POWER COMBINING BEFORE THE ANTENNA "LOCK DIAGRAMS OF REPRESEN 
 These are  the minimum target velocity that will not be suppressed by the map (so-called cutoff  velocity), its transient response, and the loss in sensitivity caused by the clutter map  (similar to a CFAR loss). The minimum cell size will be constrained by the size of the  radar resolution cell. FIGURE 2.89  Clutter map cell definition ch02.indd   84 12/20/07   1:46:53 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Because the chart is intended only to display the wide range in RCS that may be encountered in practice, the locations of targets on the chart are approximate at best. Within given classes of target the RCS may be expected to vary by as much as 20 or 30 dB, depending on frequency, aspect angle, and specific target characteristics. The reader requiringRCS(dBsm) RCS(dBsm)PULSE-GATED COMPACT RCS RANGEFREQUENCY = 10.0 GHzVERTICAL POLARIZATIONRADOME HAS BEEN REMOVED . 
 Many instances have been reported where cataracts have been deliberately formed in the  eyes of animals by exposure to microwave radiation. The viscous material of the eyeball is . 466 INTRODUCTION TO RADAR SYSTEMS  affected by heat in much the same manner as the white of an egg. 
 TRONICALLY IN ELEVATION THROUGH  RECIPROCAL BEAM 
 I05. Schrank. 11. 
 PADDING THE COLLECTED DATA AND PERFORMING A HIGHER 
 This comes about because the  intensity of the main beam increases as the square of the number of elements (AIN)~, while  the spurious radiation increases only linearly since it represents the incoherenl'addition of  many contributions."  2. The rise in the sidelobe level diie to random errors is independent of the beam scan  angle.' lo  3. The lower the design sidelobe level, the greater will be the rise in the sidelobes, assumtng a  given antenna size and a given error t~lerance."~  4. 
 G. V . Trunk and P. 
 However, one cannot ignore the RF portion of the  receiver merely by making it have wide bandwidth. Section 6.2 discussed how exces - sively wide bandwidth can penalize dynamic range if the interference is wideband  noise. Even more likely is an out-of-band source of strong interference (e.g., other  radars, TV stations, or microwave communication links) that, if allowed to reach this  point, can either overload the mixer or be converted to IF by one of the spurious  responses of the mixer. 
 Alternatively, the waveform may be generated at a low-power level and amplified  in a power amplifier. This is the more usual procedure. The waveform may be generated by a  number of means including a voitage-controlled osciIIator whose frequency is made to vary  EXTRACTION OFINFORMATION ANDWAVEFORM DESIGN423 (a) :--(? u, OJ '-'o OJ ,~:/1 11I I 1 I I I- LI .LI--------'Jo-)o Time I, 12 (b) ,------- Time (e) -1C-- 1 BI _L_~ _ I------L.-I ----------ll------~)o Timet1 t2 (e)FiguretUSLinearFMpulsecom­ pression.(a)Transmitted waveform; (b)frequency ofthetransmitted waveform; (c)representation ofthe timewaveform; (d)outputofthe pulse-compression filter;(e)sameas (b)butwithdecreasing frequency modulation. 
 GENEITY EXISTS IN A SMALL REGION ABOUT THE RANGE CELL THAT IS BEING TESTED 4HE ADAP 
 Figure 16.14 shows the way in which pulse measurement of range is used.  Figure 16.14 a shows a circular pencil beam. At angles near grazing, the illumi - nated patch set by the circular antenna pattern becomes rather long (the patch is an  ellipse), and use of the pulse length to confine illumination to a part of the patch  is helpful. 
 Performance in T est Dataset We also did an experiment with a test dataset. As shown in Table 4, because the test datasets only include 70 images, the data may undulate signiﬁcantly. The results are summarized in Table 11. 
 Thephase-comparison monopulse hasnotbeentoopopular becauseoftherelativeawkward­ nessofitsantenna(fourseparate an'tennas m'ounted topointtheirindividual beamsinthesame direction), andbecausethesidelobC"levelS)night behigherthandesired. Although sequential lobingissimilartoconicalscan,' the'l~tier:'is'preferred inmostapplications, sinceitsuffersless lossandtheantenna andfeed'systems~re .usuallylesscomplex. Inthissection, onlythe conical-scan radarandtheamplitude~c<imparison monopulse willbecompared. 
 Kock, W. E.: Related Experiments with Sound Waves and Electromagnetic Waves. Proc. 
 (b) The spectral density is given as in a but is averaged over a shorter time, 23 min. Both higher peaks and deeper voids are seen. The scale across the top of a gives the radar operating frequency that ex- periences resonant backscatter, and it can be seen that at many frequencies this level is far below the long-term average.RADAR FREQ (MHz) OCEAN WAVE FREQ (Hz)WIND VEL (KTS) (a)OCEAN WAVE FREQ (Hz)DATE 1/10/73 STARTTIME 2230 STOPTIME 2400 DATE 1/11/73 STARTTIME 0155 STOPTIME 02171l/f5(PHILLIPS EQUILIBRIUM LIMIT)PSD (dB-M2/Hz)PSD (dB-M2/Hz) . 
 EST 0ROVIDED THAT THE LIMITED 
 158-160, March,  1954.  84. McFee, R., and T. 
 Several examples of such networks for linear arrays where  shown in Figs. 8.2 and 8.4. For a planar array the problem is more complicated. 
 #7 WAVEFORMS .ONLINEARITY AT ANY STAGE HAS THE POTENTIAL TO MASK TARGET ECHOES BY MIXING THE CLUTTER ECHO WITH ITSELF  GENERATING )-$ PRODUCTS THAT EXTEND BEYOND THE INTRINSIC DOPPLER BAND OF THE CLUTTER 5NLIKE THE OUT 
 In general, single relaxations are rarely observed in natural systems. Instead,  there are distributions of relaxations corresponding to distributions of size scales  that influence movement of charge. There are several equations describing such  distributed systems, with the most common experimental observations in agreement  with the model from Cole and Cole20:  ′−′′= +− +∞∞ε ε εε ε ωταiis 1 ( ) (21.2) where a describes the breadth of the time constant distribution from a single relaxation,  a  = 1, to an infinitely broad distribution, a  = 0, with a common process. 
 This isexemplified inthe first two cases bythe Navy’s AX/APS-6 nightfighter radar and the British AIMark VIII. Helical scan isused inthe SCR-720 Army AIradar and inthe SCR-584 anti- aircraft set. Inthe latter aconical scan issuperimposed sothat the result isasort ofhelical Palmer scan. 
 In 1976, RRE was merged with the Signals Research and Development Establishment (SRDE) to become theRoyal Signals and Radar Establishment, RSRE. In 1991, the major research establishments, including RSRE and RAE, were combined as the Defence Research Agency (DRA), which became the Defence Evaluation and ResearchAgency (DERA) in 1995. In 2001, DERA was spilt into the privatised QinetiQ and the government-owned Defence Science and Technology Laboratory, Dstl. 
 SCALE SIGNAL LEVEL OF THE !$ CONVERTER AND ALSO ALLOWS FOR IMPEDANCE MATCHING OF THE MIXER AND !$ CONVERTER 4HE CONVENTION FOR THE  ) AND 1 RELATIONSHIP IS THAT THE  ) SIGNAL PHASE LEADS THE  1 SIG 
 CESSING TECHNIQUES  IT IS IMPORTANT TO INCLUDE IN THE ANALYSIS KEY DRIVERS SUCH AS SIGNAL BANDWIDTH  CLUTTER INTERNAL MOTION  PLATFORM MOTION  ANTENNA SCANNING MOTION  THE AMOUNT OF SAMPLE SUPPORT AVAILABLE FROM NONHOMOGENOUS AND NONSTATIONARY CLUTTER ENVIRONMENTS  AND OTHER EFFECTS SUCH AS LARGE TARGET SAMPLES EFFECTING THE ADAPTIVE WEIGHT SOLUTION Î°£äÊ 
 The T/R tubes recover (deionize) quickly after the transmitted pulse, which then allows received signals to flow to the receiver. A limiter is also used, as shown, to pro-(b) FIG. 4.2 Duplexers. 
 Naval Research Laboratory.30 Radars at L, S, C and X bands illuminate the aircraft target in  flight. The radar track data is used to establish the aspect angle of the target with respect to the  radar. Pulse-to-pulse radar cross section is available, but for convenience in presenting the  data the values plotted usually are an average of a large number of values taken within a 10 by  10° aspect angle interval. 
 J. Donaldson, Jr., “The measurement of cloud liquid-water content by radar,”  J. Meteorol .,   vol. 
 BASED DUCT  ITS ABIL 
 The system was supplemented in1940 by200-Mc/sec equipment, the so-called “CHL” (Chain, Home, Low) system. Itwas often very difficult tofind sites that were flat enough forstations. Since thestation atDover was ona400-ft cliff and Ventnor was onacliff 1000 ftabove thesea, itwas im~ossible forthese stations to measure height atall. 
  
 (Chicago),  vol. 10, pp. 109-118, 1954. 
 DEPENDENT )F FREQUENCY IS CHANGED AND THE PHASE SHIFTERS ARE NOT CHANGED  THE BEAM WILL MOVE &OR AN EQUAL 
 13”22, ontheother hand, transmits only that portion ofthesignal inwhich the voltage exceeds the applied potential, sothat ineffect the bottom isclipped. This arrangement isofconsiderable importance in time-measuring applications. Ifavery linear sawtooth isapplied tothe 1Soxnetirnea theresistor ismadeslightly morenegative thanVoinorder toholdA tightly against thediode during theclamping period.. 
 Skolnik. (ed.), New York:  McGraw-Hill, 1970, Chapter 31.  7. 
 ORDER #)# DECIMATION FILTER  A  BEFORE DECIMATION  AND B  AFTER DECIMATION           
 99, pt. 111, pp. 37-44, March, 1952. 
 1977. IliE (I,o~itlo~i) C'onf.  Pirhl. 
   PP   *ANUARY    % & +NOTT  ! 7 2EED  AND 0 3 0 7EI  h"ROADSIDE ECHOES FROM WIRES AND STRINGS v  -ICROWAVE  *OURNAL  PP  ET SEQ  *ANUARY    3 3 #HANG AND 6  6 ,IEPA  h-EASURED BACKSCATTERING CROSS SECTION OF THIN  WIRES  5NIVERSITY OF  -ICHIGAN  2AD ,AB 2EPT  
 A radar system that has the capabil - ity of changing frequency over a very wide bandwidth can, with advantage, adapt its  transmission to take into account frequency-dependent multipath characteristics, tar - get response, environmental conditions, interference, and jamming. Further, wideband  processing can give fine range resolution. Phased arrays have the potential of operating over very wide bandwidths. 
 GROUND PENETRATING RADAR  21.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 In the case of antennas operated in close proximity to the ground, the antenna charac - teristics may vary as a result of changes in the ground surface electrical parameters.  Any processing scheme that assumes the antenna parameters remain constant needs  to account for the mode of operation of the antennas and the degree of stability that is  practically realizable. This is a particular issue for GPR and needs careful attention to  reduce the effect of antenna-ground surface interaction. 
 512-521.  September, 1977.  77. 
 DEPENDENT WEIGHT ADJUSTMENT TO REDUCE THE EFFECT OF UNWANTED  &)'52%  4HE ADAPTIVE ARRAY SCHEME                  
 Indeed, there are many tracking applications where an operator has no place, as in  a homing missile or in a small space vehicle.  The technique for automatically tracking in range is based on the split range gate. Two  range gates are generated as shown in Fig. 
 SPILL DETECTION BY MARINE 8 
    
 02& WAVEFORMS ARE USED -ULTIPLE $ISCRETE 02& 2ANGING  4HE TECHNIQUES FOR CALCULATING TRUE RANGE  FROM SEVERAL AMBIGUOUS MEASUREMENTS GENERALLY INVOLVE SEQUENTIAL MEASUREMENT OF THE AMBIGUOUS RANGE IN EACH 02&  FOLLOWED BY AN  UNFOLDING AND CORRELATION PROCESS  4HE UNFOLDING CREATES A VECTOR OF POSSIBLE RANGES FOR EACH VALID DETECTION BY ADDING A SET OF INTEGERS ; x += TIMES THE UNAMBIGUOUS RANGE INTERVAL   22C F+ 2UNFOLD AMBIGUOUS    ;=     WHERE THE UNAMBIGUOUS RANGE INTERVAL    CF2   WITH C   SPEED OF LIGHT AND  F2   02&  4HE SET OF INTEGERS ;x += ARE REFERRED TO AS THE RANGE AMBIGUITY NUMBERS  WITH  + DETER 
 &ED 3ERIES &EED ! CENTER 
 17.9.) Eclipsing and Range-Gate Straddle Loss. Because of eclipsing, the value of R0, given by Eq. (17.20), may fall anywhere between zero and a maximum value, depending on the exact location of the target return in the interpulse period. 
 Images with random crop. ( a–c) are three examples of images with random crop. Rotating is also a popular way for data augmentation, it can keep main information of images. 
 It houses a broadside array of Yagi-type  endfire elements.  l . :,J . 
 RANGE PRECIPITATION RADARS 4HROUGH PULSE 
 Cavaleri41) FIGURE 15.12  Examples of clutter probability distributions  at low grazing angles ( after D. Trizna42) ch15.indd   17 12/15/07   6:17:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 INCIDENCE RERADIATION PATTERNS OF FACETS &)'52%   A  &ACET MODEL OF A RADAR RETURN . £È°£ä  2!$!2 (!.$"//+  POINTS FROM THE MEAN PLANE &OR SURFACES ASSUMED TO BE AZIMUTHALLY ISOTROPIC  THE  USUAL APPROACH YIELDS INTEGRALS OF THE FORM    COSCOS   COS   ;   = QXQ X XSQ R XE* K DKH 
 K. Fung37) ch16.indd   5 12/19/07   4:54:23 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 In addition, there are several centers of subsidence areas in Wuchang, Qingshan, Hanyang, and Hongshan district. 221. Sensors 2019 ,19, 743 Bai et al. 
 IEEE Standard Dictionary of Electrical and Electronic Terms , 4th Ed. New York: IEEE, 1988.  2. 
 TIME 34!0 PROVIDES SUPERIOR INTERFERENCE CANCELLATION THAN SPATIAL 
 Slices of SAR ship image are obtained by target detection. And with the aid of the real ground information provided by AIS, all vessels are manually annotated by interpretation experts. The data set includes a total of three types of ships: Bulk Carrier (B), Container Ship (C), and Oil Tanker (OT). 
 H. T.. and C. 
 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24   blind folio 24.68 ch24.indd   68 12/19/07   6:01:20 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 FIGURE 13.46  AN/TPS-78 antenna ( Courtesy of Northrop  Grumman Corporation ) ch13.indd   66 12/17/07   2:41:14 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 TO 
   !.403 
 R. G. Medhurst, “Rainfall attenuation of centimeter waves: comparison of theory and measure - ment,” IEEE Trans. 
 DRAG AERODYNAMIC FINS SUFFICIENT TO MAINTAIN STABLE FLIGHT 4HE DECOY DIVERGES FROM THE VELOCITY VECTOR OF THE LAUNCH AIRCRAFT BY NATURAL DECELERATION AS A RESULT OF AIR STREAM AND FALLING DUE TO GRAVITY 4HE DECOY TYPICALLY STARTS RADIATING JAMMING SIGNALS TOWARD THE MISSILE SEEKER IMMEDIATELY AFTER EJECTION FROM THE AIRCRAFT AND CONTINUES RADIATION THROUGHOUT ITS FLIGHT $ECOY EJECTION IS TYPICALLY COMMENCED WHEN THE 272 DETECTS INCOMING RADAR 
 BANDWIDTH PULSE COMPRESSION WAVEFORMS CAN OFFER GREATER CLUTTER REJECTION&ACTOR ,INEAR &- .ONLINEAR &- "INARY 0HASE #ODED0OLYPHASE #ODED $OPPLER  TOLERANCE3UPPORTS DOPPLER SHIFTS UP TO o "  4IME SHIFT OF F D4"  IS INTRODUCED BY  RANGE 
 23-26, January, 1960.  88. Bayliss, E. 
 Avariant ofthis scheme turns thereceiver offduring one modulation. 150 C-W RADAR SYSTEMS [SEC. 5.11 cycle, and turns thetransmitter offand thereceiver onduring thefollow- ing cycle. 
 F., and BAmN-  BRIDGE-BELL, L. H.: Applications of the Cathode  Ray Oscillograph in Radio Research (H.M. Stationery  Office, 1933). 
 While GNSS, enhanced by the growing use of electronic charts, has helped greatly  in informing mariners of the precise position of their vessel, radar is still used as an  important secondary source of position. Reliance on GNSS alone has been at the  root of many marine accidents. The main use of marine radar is to assist collision avoidance. 
 EYE IS BASICALLY A TWO 
 The implementation of this measurement capability is more com-  plicated than a short-pulse radar without angle sensing. Also, it cannot be employed when  the target angular extent is less than the sensitivity of the monopulse measurement.  Engine modulations. 
 Figure 12.7 shows that a target  located at the geometrical horizon is not in free space but is definitely within the diffraction  region of the rapar. The field strength for a target on the radar line of sight might vary from 10  to 30 dB below that in free space.43 The loss of signal strength in the diffraction region can be  quite high. At a frequency of 500 MHz, the one-way propagation loss is roughly 1 dB/mi at  low altitudes. 
 The alternative istoseparate thesignals intime, thevideo signals being excluded from the transmitter during aninterval prior to and including the pulse. The trigger channel atthe receiving station is blocked byanelectronic switch except when the pulse isexpected. .Means for accomplishing both ofthese separation methods will be described later. 
 BAND LIGHT WEIGHT MIRROR DESIGN v  )%%%  4RANS  VOL !0 
 Thereislittleintegration improvement obtained fromthese 60pulsessincetheyoccurwithinatime(ins)comparable tothedecorrelation timefor X-bandseaclutter.Iftheantenna rotation rateisspeeded lipto600rpm,therewillbe2 pulsesreceived duringascanpastatarget.(Thereshouldbeatleast2pulsesperscanrather thanone,inordertoavoidalargescanning loss.)Onthenextscan,one-ll.:nl.h secondlater,two additional pulsesarereceived thataredecorrelated fromtheprevious twopulsessolhatan integration improvement canbeobtained. Thenumberofpulsesprocessed hytheslow-speed andthehigh-speed antennas arethesame.The20rpmantenna receives 60pulsesperscan witha3-second rotation period.Inthesame3seconds, the600rpmantenna scansbythe target30times,receiving twopulsesoneachscan.Ascan-to-scan integration improvement canbeachieved withthehigh-speed antenna ifthestorageproperties oftheCRTscreenpermit efficient integration (aswithastoragetube)orifsomeformofautomatic integration isused. Experimental measurements usingcivil-marine radarwitha 10beamwidth and5000Hz pulserepetition frequency showthatincreasing theantenna rotation ratefrom20to 420rpmimproves thetarget-to-clutter ratiofromabout4to8dBdepending onthesea state.H(Thesmallerimprovement corresponds tothehigherseastate.)Anattempt wasalso. 
 The  plots show that operation on a single frequency may experience less than ±3 dB varia - tion over a range interval of 1000 km. Also, if frequency selection had been made with  a 2-MHz granularity instead of the 1 MHz used, the SNR would be reduced by only  a decibel or so. FIGURE 20.29  The numbers in this figure show the SNR in dB as a function of frequency and range in  the form of an oblique sounding, as in Figure 20.28, but for 0800 GMT (night). 
 TheeffectofECMonasingleradarcanseldombeconsidered in isolation sinceitisseldomthatasingleradaractsasanentityinitself.Amilitary radaris. almostalwaysinsupport ofaweapon system.Thequestion isnotwhether asingleradarcan operate without degradation, butwhether theweapon systemofwhichtheradarisapartcan fulfillitsmission inspiteofhostileECM.Itiseasiertoensuretheaccomplishment ofthe weapon system's mission thantoguarantee thatoperation ofasingleradarwillnotbe degraded. Thislargerandmoreimportant goal,thatoffulfilling amilitary mission. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°xÇ 73 ABOARD THE %23 
 9785–9801, 1994. 73. B. 
 The statistics  include data collected at nominal wavelengths of 3.25, 10.7, and 23 cm for ship dis - placements ranging from 2 to 17 kilotons. Figure 14.14 summarizes the general RCS levels of the wide variety of targets  discussed in this section, with the RCS of a metallic sphere shown as a function of its  volume for comparison. The ordinate is the RCS in square meters, and the abscissa is  the volume of the target in cubic feet. 
 High-power, large antenna apertures, and good MTI are easier to achieve at frequencies  below L band. Also, weather clutter is much less. The lower the frequency the easier it is to  obtain long range. 
 292-296.  42. Bogotch, S. 
 62. Spafford, L. J.: Optimum Radar Signal Processing in Clutter, I EEE Trans.. 
 ATE OVER ICE &IGURE   )TS PAYLOAD INSTRUMENT IS THE 3!2)NTERFEROMETRIC 2ADAR !,TIMETER 3)2!,   WHICH HAS THREE MODES #ONVENTIONAL  3!2  AND )NTERFEROMETRIC 4HE #ONVENTIONAL MODE PULSE 
 The usual rules ofaccessibility and convenience will dictate theplacement ofparts. If,however, theunit istobepressurized, further consideration must be given tothe container. Itisalmost essential tobeable toremove the pressure cover and make tests and adjustments without disconnecting the r-ftransmission line orany power orsignal cable. 
   2!$!2 #2/33 3%#4)/.   £{°Î TARGET ASPECT ANGLE AS SEEN FROM THE RADAR 3OME ARE DOMINANT S CATTERING MECHANISMS  WHEREAS OTHERS ARE WEAK .OT ALL ARE SIGNIFICANT ON OTHER KINDS OF PLATFORMS  SUCH AS  WARSHIPS OR MILITARY GROUND VEHICLES 7E BRIEFLY DISCUSS THE SEVEN IN DESCENDING ORDER OF SIGNIFICANCE 2EENTRANT 3TRUCTURES  4HE ONLY REENTRANT STRUCTURE APPEARING ON THE HYPOTHETI 
 £SINC   SINC   SINC  
 AP-8, pp. 286-297, May, 1960; pt. 11, Compensation EKects, pp. 
 D.C.  67. Easton, R. 
 For traveling, itislowered within thetrailer. Aconical scan isexecuted bytheantenna oftheSCR-584, thedipole feed ofthe6-ft paraboloid rotating rapidly about anaxis which isthat of itsmechanical, tbough notitselectrical, symme try. For precision track- ing, theazimuth and elevation error signals derived from this conical scan areused, nottogive anindication ofpointing error, but actually todrive servomechanisms which ~osition the antenna mount. 
 NELS ASSIGNED FOR !)3 USE 4HE TRANSMITTED INFORMATION IS RECEIVED BY OTHER SHIPS AND ALSO BY SHORE STATIONS  SUCH AS COASTAL AUTHORITIES AND 643 FACILITIES 3HORE STATIONS AND SHIPS ALSO HAVE THE ABILITY TO SPECIFICALLY INTERROGATE SHIPBORNE !)3 TRANSPONDERS TO INITIATE THE SENDING OF PARTICULAR DATA !)3 HAS THREE MAJOR USES TO ENHANCE THE BRIDGE TEAMS SITUATIONAL AWARENESS  TO AID 643 ACTIVITIES  AND TO PROVIDE DATA TO ASSIST NATIONAL SECURITY 4HE INTENTION OF )-/ IS THAT SHIPS WILL NORMALLY DISPLAY !)3 DATA ON THE RADAR SCREEN AS IT COMPLEMENTS RADAR 
 D), vol. 83, pp. 95–107, 1961. 
 The relatively fat cathode, required for theoretical reasons, can dissipate more heat  than can a thin cathode.  In the interaction space (5) the electrons interact with the d-c electric field and the  magnetic field in such a manner that the electrons give up their energy to the RF field. The  magnetic field, which is perpendicular to the plane of the figure, passes throtrgh the interaction  space parallel to the cathode and perpendicular to the d-c electric field. 
 D" INCREASE IN THE TRANSMITTED CONFIRMATION ENERGY ADDITIONAL ENERGY IS ALSO AVAILABLE BY PLACING THE TARGET IN THE CENTER OF THE CONFIRMA 
 AES-1 I. pp. 768 780. 
 The appearance of the focused image obtained is comparable with standard RD focusing, as shown in Figure 9. To assess the performance of the proposed approach, point scatterer responses have been compared between the RD and B-SAR focused images, showing a pretty good correspondence. Also, the problem of phase stability of the algorithm has been addressed, computing the interference fringes corresponding to an ERS 1-2 tandem mission, showing also good adherence of the speciﬁc local orography. 
 TO 
 W. Judd, “Technique for realizing low time sidelobe levels in small compression ratio chirp  waveforms,” Proc. IEEE Ultrasonics Symp ., 1973, pp. 
 The azimuth along-track signals from a point target are similar to those of a zone plate. The focal length is proportional to target range. If pulse compression is used, all targets have associated with them zone plates in the range direction. 
 1.4 THE RADAR EQUATION The radar range equation (or radar equation, for short) not only serves the very useful  purpose of estimating the range of a radar as a function of the radar characteristics,  ch01.indd   10 11/30/07   4:33:44 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 
 Smith, R. N. Morton, and W. 
 Itwill, however, beinstruc- tive toconsider briefly afew typical systems. 7.6. Radar inthe RAF Fighter Command .-Just asthe first radar equipment tobeused inoperations was that installed fortheairdefense oftheBritish Isles, sothe first operating radar organization was that of RAF Fighter Command, theuser ofthis equipment. 
 RANGE SURVEILLANCE IS BETTER PERFORMED AT LOW FRE 
 Tang, C. H., et al.: Bistatic Radar Measurements of Electrical Properties of the Mar- tian Surface, J. Geophys. 
 Intercept receivers and direction finders (which are  called electronic support measures, or ESM), as well as antiradiation missiles (ARM) are also  aspects of electronic warfare (EW) that must be of concern to the military radar systems  designer.  If a determined adversary is willing to pay the resultant price, sufficient ECM can be  brought to bear against any single radar to significantly reduce its effectiveness. This should  not evoke pessimism on the part or the radar designer since it can be said that any military  objective can be accomplished by a determined force if the force is skillful and large enough,  and if cosl is of no consequence. 
 Tkac, and M. Kmec, “Digital ultra-wideband-sensor electronics integrated  in SiGe-technology,” in Proc. of the EuMC , vol. 
 Barrick, D. E.: FM/CW Radar Signals and Digital Processing, National Oceanic and At~nosplteric  Adnritristration, Boulder. Colorado. 
 -In some cases ithas not been feasible touse a single spot frequency ofreply either because thenumber ofreplies atthe frequency would beexcessive orbecause itwas not practical tomodify a group ofradar sets toreceive the chosen frequency. Inthese cases, beacons have been used inwhich the common frequency ofreceiver and transmitter was made tosweep periodically over theband offrequencies ofthe interrogators. Agiven interrogator got replies when the beacon came into tune with it. 
 The four tluctua­ tion models are as follows:  Case /. The echo pulses received from a target on any one scan are of constant amplitude  throughout the entire scan but are independent (uncorrelated) from scan to scan. This  assumption ignores the effect of the antenna beam shape on the echo amplitude. 
 108. Gossard, E. E., and W. 
 Thereflective-array compressor (RAe)formofSAWdevice,shownschematically in Fig.11.17c,isageometry thatprovides betterperformance forlargepulse-compression ratios.22Shallow grooves etchedinthedelaypathresultinSAWreflections toformadelay thatdepends onthefrequency. Thestructure islesssensitive tofabrication tolerances than convention~l transducers. A..typical" SAWdispersive delaylinedeveloped forlinearFMpulse-compression radar hadabandwidth of500MHzandalluncompressed pulsewidth'of 0.46ILS.23Thecenter frequency was1.3GHzandthecompressed pulsewidthwas3ns.Amplitude weighting ofthe received signalreduced thehighestsidelobeto-24dBinsteadof-13.2dBwithoutweight­ ing.(Thecompressed pulsewaswidened because oftheweighting.) Thefilterpackage measured 0.5by1.5by2.25in.Themaximum insertion losswas40dB.Otherdesignshave resulted inpulsewidthsaslongas100/lSandpulse-compression ratiosashighas10,000.22 TheSAWdispersive delaylineisoneofthemoreimportant ofthemanydevicesthathave beenemployed forpulse-compression radar.Theyhavebeenclaimed tobesimple,lowcost, I IFigure1I.18Interdigital transducer (nondispersive) showing overlapofcombfingers,orelectrodes, toprovideanamplitude weighting alongthepulse.. 
 E. Wood: System Considerations for the Design of Radar Braking Sensors,  IEEE Trans., vol. VT-26. 
 In addition, the NRCS dynamic range of the background can also affect the visibility of the eddy, so Δσris deﬁned as the NRCS contrast of the entire background image; it is also calculated from twenty pixels on average similar to Δσ. The larger the value of Δσr, the larger the NRCS contrast of the overall SAR image. Fifty simulations under each radar frequency have been conducted; the eddy spiral features and the calculated ΔσandΔσrare almost the same. 
 These approaches provide only limited range coverage, and overlapped processors are needed for all-range performance. Fig- ure 10.4a shows a digital implementation of a correlation processor that will pro- vide matched-filter performance for any radar waveform. Figure 10.4£ shows a Cb) FIG. 
 Throughout WWII these radars were being tested and evaluated, both in order to improve their design and maintenance and also to developappropriate strategies for their use. A number of different research, development and trials organisations are mentioned throughout the book. A brief summary of these is given here and further details of their work will be found in the relevant chapters. 
 Some arbitrary procedure forobservation must bespecified, and thelimit ofrange must bedefined. SEC.212] I’RO1’AGA TIO.V01’ER.1lil?l~Lh’CTI.VG ,$’171tl’ACE 47 inamanner consistent with the inherently statistical nature ofthe problem. That R..,isnot rendered souncertain bythese statistical effects astolose any usefulness islargely due totheinverse-fourth-power law expressed bythe radar equation, which makes the range relatively insensitive tomoderate changes inthesystem parameters. 
 enclosed by a 150-ft diameter metal space-frame randome. It was designed to oper­ ate at freque.pcies from 2 to 10 GHz for radar, radio astronomy, and space communications.  To facilitate multifunction use, the RF components are installed in a number of plug-in  modules, 8 by 8 by 12 feet in size, which mount directly behind the Cassegrain reflector. 
 In this example, an A/D conversion rate of f fAD IF = ⋅4 3 is assumed. The  optimum choice of the A/D converter sampling rate ensures that the negative part of  the spectrum has the smallest possible overlap with the positive part of the spectrum. The smallest possible overlap occurs when the A/D sampling rate is related to the  radar IF frequency as follows43:  ff MADIF=⋅ ⋅ −4 2 1 (2.60) where M is an integer greater than 1. 
 (Published by Raytheon Co., Lexington, Mass.)  60. Barton, D. K.: Sputnik I1 as Observed by C-Band Radar, 1959 IRE National COIIV. 
 A sacrifice in bandwidth must be made if  high-power is required of a TWT. If the bandwidth is too small, however, there is little  advantage to be gained with a traveling-wave tube as compared with multicavity klystrons.  A klystron can be operated over a fairly wide range of beam voltage without a large  change in the gain characteristics. 
 Theoutputofthe opticalprocessor isamaplike photographic filmoftheterrain,asinFig.14.4.TheSAR produces imageswithouttheslant-range distortion thatoccurswiththephotographic camera. Theradaroutputisstoredonfilmasdepicted inFig.14.5.Theoutputoftheradar receiver isappliedtothe."zaxis"ofacathode-ray tubesoasto'produce anintensity­ modulatedverticalsweep.Theverticaldel1ection oftheCRTisinsynchronism withtherange sweepoftheradar.I\.lensfocusestheCRToutputonamovingstripoffilmwhoserateof travelisproportional tothespeedofthevehiclecarrying theradar.Theverticaldimension on thefilmrepresents therangeandthehorizontal dimension represents thecross-range, cr along-trac~coordinate. Returnsfromasinglepoint-target fallonahorizontallin~. 
 10, pp. 77-79, October, 1967.  10. 
 VIEW PHASED ARRAY APERTURE TO ACQUIRE THEATER MISSILE THREATS AT A RANGE OF UP TO   KM 4HIS RADAR USES   8 
 TPT P A   =T 
 From Levanon17 we have  R RV t RR RA max min( / ), ≅ + =02 2 002 2 (17.24) where R0 = distance from the radar to the scene center in the middle of the data collec - tion interval, and Rmax = distance from the radar to the scene center at the beginning  and end of the data collection interval. Then  ∆∆R R RVt RL RR RA= − = = = =max min( ) ( )2 02 002 0 8 8 8SA θ λ2 2 232δδ cr<r (17.25) The last inequality is necessary for the condition of no range migration. For exam - ple, parameters for a SAR might be R0 = 200 km, l = 0.03 m, and dr = dcr = 1 m; then,  ∆R = 5.6 m > dr, and the condition is not satisfied. 
 The illuminations of the basic MAM method and the EMAM method. ( a) The basic MAM method; ( b) the EMAM method. Δfd,ijis the position offset between the sub- iimage and sub- jimage. 
 38.Friichtenicht, H.W.:NotesonDuctInfluences onLine-or-Sight Propagation, IEEETrails., vol.Ap·22,pro295-302, March,1974. 39.Stewart, C.H.,andG.J.Vincent: Radar-Tracking Accuracy Incn:ased, Electrollics, vol.37,pp.7375, May4,1964. 40.Bean,B.R.,andE.J.Dutton:"RadioMeteorology," National BureauofStandards Monograph 92, Mar.I,1966. 
 The linear azimuth resolution for the conventional case is given by \ D Resolutionconv = — (21.6) For the unfocused case, the resolution is Resolutionunf = 1X2Vx/? (21.7) whereas for the focused case, the resolution is Resolutionfoc = — (21.8) where X = wavelength of radar signal transmitted D = horizontal aperture of antenna R = radar range Figure 21.1 is a plot of the resolution for each of these cases as a function of radar range. This plot is for an antenna aperture of 5 ft and a wavelength of 0.1 ft. Conventional Technique. 
 F. : Stcppctl-irldcx I.tt~ichurg Lenses, Elc~ctrortic Desigtl, vol. 8, pp. 
 4.12 Klystrons  ...........................................................  4.14  Traveling-Wave Tubes (TWTs)  ..........................  4.15 RF Tube Selection  ............................................. 
 The human eye is, of  course, a system for producing images using visible light. The light hits the lens and is  focused upon the retina, and the resulting image is transmitted to the brain. Over many  millennia, humans have become fully accustomed to seeing and processing this vis - ible imagery. 
 BAND FREQUENCIES )N PAR 
 Thereceiver isusuallyofthesuperheterodyne type.Thefirststagemightbealow-noise RFamplifier. suchasaparametric amplifier oralow-noise transistor. However. 
 RANGE RESOLUTION OF  KM AT A RANGE OF  KM "ECAUSE THUNDERSTORMS CONTAIN IMPORTANT SPATIAL FEATURES  SUCH  AS HEAVY PRECIPITA 
 Therefore  ( 1. 7)  This is the fundamental form of the radar equation. Note that the important antenna par­ ameters are the transmitting gain and the receiving effective area. 
 L.-L. Fu and A. Cazanave (eds.), Satellite Altimetry and the Earth Sciences , San Diego:  Academic Press, 2001. 
   4 y .4   02&   F 2 7E ASSUME OPERATION AT BASEBAND  AND  THUS THE FREQUENCY IN QUESTION IS THE APPARENT DOPPLER FREQUENCY OF THE TARGETS 7E CONVERT THIS TO CROSSRANGE BY MULTIPLYING BY K7   K26   DLL LL CR 3!y y 7$42 ,2 64 P    .OTE  THAT OUR ASSUMPTION THAT  2  64 PERMITS THE USE OF SMALL 
 25.2 HISTORY Early experimental radars in the United States, the United Kingdom, France, the Soviet Union, Germany, and Japan were of the bistatic type, where the transmit- ter and receiver were separated by a distance comparable to the target distance.21"26 These bistatic radars used CW transmitters and detected a beat fre- quency produced between the direct-path signal from the transmitter and the doppler-frequency-shifted signal scattered by a moving target. This effect was called CW wave interference.1 The geometry was similar to that of the forward- scatter (or near-forward-scatter) configuration, where the target position is near the baseline joining transmitter and receiver. Much of the early bistatic radar technology was derived from existing communications technology—separated sites, CW transmissions, and frequencies ranging from 25 to 80 MHz.27 These early bistatic radars were typically configured as fixed, ground-based fences to detect the presence of aircraft: a major, emerging threat in the 1930s. 
 74,  May, 1974.  149. O'Donovan, P. 
 50 A minimum of three feeds (or elements) is necessary  to resolve two targets, but antennas with from four to nine elements in the vertical dimension  have been considered. Another approach that depends on additional antenna feeds, or degrees  of freedom, employs a monopulse tracker with a difference pattern containing a second null  which is independently steerable. This null is maintained in the direction of the image, as  computed by Snell's law for the measured target range. 
 02& AND HIGH 
 423–437.  5. R. 
 RESPONDING WINTER CASE IS PRESENTED IN &IGURE  3UCH PLOTS CAN BE USED TO DETERMINE THE MAXIMUM FREQUENCY THAT WILL PROPAGATE TO A GIVEN RANGE IN MOST CASES  THE OPTIMUM FREQUENCY IS JUST BELOW THE MAXIMUM FREQUENCY &OR THE LITTLE TABLES SHOWN IN &IGURE  AND   &# IS THE CRITICAL FREQUENCY  IN MEGAHERTZ (# IS THE HEIGHT OF MAXIMUM IONIZATION OR THE NOSE OF THE PARABOLA  IN KILOMETERS AND 9- IS THE SEMILAYER THICKNESS  IN KILOMETERS %S DESCRIBES THE STATISTICAL RANGE OF VARIATION OF SPORADIC 
 PGIT-3, pp.  68-89, March, 1954.  10. 
 alters the phase front of the field radiated by the planar array to cause a  change in the direction of propagation. The dome acts as an RF analog to an optical prism  that changes the scan angle of the planar array by a factor K(O). For example, a constant value  of K = 1.5 extends the coverage of a ± 60° planar array to ± 90°. 
 TRACK IS PREFERRED AFTER 7"ATH Ú )%%  . 
 542,  547 553  Elevated ducts, 453  Eridfire array. 279  Engine modulations, 435  Envelope detector, 23. 382-385  I:~~virotlrnenld noisc, 461 465  l!q\ripmctit instabilities. 
 7, pp. 218–232, 1990. 149. 
 3 RADAR SYSTEMS 4ABLE  SHOWS THE RANGE OF PARAMETERS THAT CAN BE OBSERVED AS A FUNCTION OF RADAR MODE 4HE PARAMETER RANGES LISTED ARE 02&  PULSE WIDTH  DUTY CYCLE  PULSE COMPRESSION RATIO  INDEPENDENT FREQUENCY LOOKS  PULSES PER COHERENT PROCESSING INTERVAL #0)   TRANSMITTED BANDWIDTH  AND TOTAL PULSES IN A 4IME 
 Let usassume, forexample, that the locking pulse causes the coherent oscillator toexecute forced vibrations atthe intermediate fre- quency fortheduration ofthepulse, after which itreverts toitsnatural frequency. Then thevariation inphase ofthecoherent oscillator isgiven byA,.Af(incycles), where Ajisthe amount bywhich the coherent. 642 MOVING-TARGET INDICATION [SEC. 
 LIKE PULSES !N EXAMPLE OF A WAVEFORM FOR A MEDIUM 
 "Advances inElectronics andElectron Physics," vol.45, editedbyL.Marton, Academic Press,Inc.,NewYork,1978,pp.203-2~2. AlsoTrunk,G.V.:Survey ofRadarSignalProcessing, NavalResearch Laboratory Report8117,Washington, D.C.,June21, /977. 64.Hansen, V.G.:Performance oftheAnalogMoving Window Detector, IEEETrans.,vol.AES-6, pp./73-/79, March,1970. 
 13.5 for sea state l by proper  selection of the parameters. Other pdf's that have been suggested for approximating non­ Rayleigh sea clutter include the Ricean 13 [Eq. (2.27) ], the chi-square 1 3 [Eq. 
 M. Reid, and M. Tsutsumi, “The meteor radar response func - tion: Application to the interpretation of meteor backscatter at medium frequency,”  J. 
 The fewer the adjustable elements the more practical is the adaptive array.  One potential application of adaptive a·rray antennas is for airborne surveillance radar.  In addition to the reduction of jamming noise which enter the airborne surveillance radar,  it is important to reduce the clutter that enters via the radar antenna sidelobes. 
 '2!- *ET 0ROPULSION ,ABORATORY   VOL   PP n    2 +WOK AND 7 4 + *OHNSON  h"LOCK ADAPTIVE QUANTIZATION OF -AGELLAN 3!2 DATA v  )%%%  4RANSACTIONS ON 'EOSCIENCE AND 2EMOTE 3ENSING  VOL   PP n    ' ' 3TOKES  h/N THE COMPOSITION AND RESOLUTION OF STREAMS OF POLARIZED LIGHT FROM DIFFERENT  SOURCES v 4RANSACTIONS OF THE #AMBRIDGE 0HILOSOPHICAL 3OCIETY  VOL   PP n    3 2 #LOUDE AND % 0OTTIER  h! REVIEW OF TARGET DECOMPOSITION THEOREMS IN RADAR POLARIMETRY v  )%%% 4RANS 'EOSCIENCE AND 2EMOTE 3ENSING  VOL   PP n    2 + 2ANEY  h3TOKES PARAMETERS AND HYBRID 
 KM BY  
 CONTROLLED TUBE KNOWN AS THE CONSTANT EFFICIENCY AMPLIFIER #%!  . 
 763–768,  1974. 43. R. 
 M. W. Long, Radar Reflectivity of Land and Sea , 3rd Ed., Norwood, MA: Artech House,  2001. 
 Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 17 .20  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 complex numbers that each results from one of the scatterers. Thus, when terrain,  especially vegetation, is imaged, the amplitude (voltage) of a particular pixel is the  magnitude of the complex sum of the coherent returns from many scatterers within  the pixel. 
 VI- 4-1-VI-4-19, New Mexico State University, Las Cruces, Mar. 8-10, 1978. 16. 
 52. D. K. 
 4.8 LI~II'I'A'I'IONS TO MTI PERFORMANCE  Tlie iinprovement in signal-to-clutter ratio of an MTI is affected by factors other than the  design of the doppler signal processor. Instabilities of the transmitter and receiver, physical  niotions of the clutter, the finite time on target (or scanning modulation), and limiting in the  receiver can all detract from the performance of an MTI radar. Before discussing these effects,  soii~e dcfiriitioris will be stated. 
 New York, 1958.  6. Bendat. 
 This results in sea or ground clutter being present at all ranges of interest. Other clutter sources such as rain and chaff may coexist with the surface clutter. In most instances these sources are moving at a speed determined by the mean wind aloft and have a mean doppler frequency significantly different from that of the surface clutter. 
 It is thus possible to determine when the  target is in the low-angle region by sensing large elevation-angle errors and locking the  antenna in elevation at some small positive angle while continuing closed-loop azimuth  tracking.43 This is sometimes called off-axis tracking,45 or o.ff-boresight tracking:P The eleva­ tion angle at which the antenna is fixed depends on the terrain and the antenna pattern.  Typically it might be about 0.7 to 0.8 beamwidth. With the beam fixed at a positiv~ elevation  angle, the elevation-angle error may then be determined open-loop from the error-signal  voltage or the elevation measurement may sfrnpJy . 
 Memo TG-899, April 1967. 11. D. 
 R. E. Ziemer and J. 
   PP n  *ULY   7 7 3HRADER  h-4) 2ADAR v #HAP  IN  2ADAR (ANDBOOK   - ) 3KOLNIK ED   .EW 9ORK  -C'RAW 
  
 The radiating elements are not isotropic but have a radiation pattern Ee(Q), known as the element factor or element pattern', then the complete radiation pat- tern E(0) is the product of the array factor and the element pattern: sin [MT(s/X) sin 6] E(0) = Ee№a(Q) = Ee(0) . J (7.3)N sin [TT(J/X) sin 0] An approximation to the pattern of Eq. (7.2) is in the form sin [ir(fl/X) sin 0] £(8) = —— (7.4)ir(fl/X) sin 0]|Ea<e>| TT i. 
 84. McFee, R., and T. M. 
 DOPPLER CONTOURS  DEFINE THE AREA THAT CONTRIBUTES TO CLUTTER IN THE SELECTED DOPPLER FILTER 4HE SHADED INTERSECTIONS REPRESENT THE AREA  OR CLUTTER PATCHES  THAT CONTRIBUTES TO THE RANGE 
 7.26/, i:  G 00 + [ l/(csc2 00)] csc2 0 dO  (7.28)  For small values of 00,  G G ~ 2 -Oo cot Om  C (7.29) . 260 JNTRODUCTION TO RADAR SYSTEMS  Figure 7.25 Cosecant-squared antenna of the AN(TPN-19 landing system. (Courtesy Raytheon Compm1,1.)  C  0  CJ>  QJ  >  a  QJ n::  0  (al QJ  >  0  OJ a::  0  ( D) Figure 7.26 Idealized anlcnna pat­ tern assumed in the com put.ti ion of  the loss in gain incurred with a  cosecant-squared antenna pattern. 
 P. Thompson, and W. D. 
 1, Mar. 26, 1956; vols. 2 and 3, Apr. 
 Al- though only one hop is shown, a multiplicity will exist, and energy may at times circle the earth. In the upper-right sketch, the ray paths show that different range extents are illuminated by using different operating frequencies, the longer ranges requiring the higher frequencies. In the example, 500 nmi is shown as the range coverage extent illuminated by one operating frequency. 
 Since arather large sawtooth (=100 volts) isgenerated without exponential correction, the sweep slows down slightly toward theend. Asisshown, two sweep speeds areprovided, one of300 psec using C, astheintegrating condenser, and asecond ofapproximately 5psec using the stray capacity atpoint 1?. More values can ofcourse beprovided byadding more switch points and condensers. 
 29. J. M. 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 24.36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 effectively for the targets that survive, and so in this way, it can prevent the overall  failure of the radar. In the limit of no targets being detected (i.e., a very powerful jam - mer), then it could still be argued that no tracks are better than many false tracks. 
 78. Woodward. P. 
 m 8 t)  7  "' 6  V,  0 5 C  ' 4  3  u 2 0 .c  V, -I '" -'-.c f-0  +' 10 20 30 40 60 80 100 200 300 400  Number of pulses integrated  Figure 10.6 Improvement of operator detection threshold (signal-to-noise ratio per pulse) as a function of  the number of pulses (sweeps) for side-by-side displays. Curve A, chemical recorder; curve B, cathode-ray­ tube B-scope display; curve C, line or slope 1.5 dB/doubling ( oc n1'2); curve D, line of slope 3 dB/doubling  ( rx n) for perfect predetection integration . .a.'s are theoretical values for ideal postdetection-integration  improvement as computed by Marcum43 for a false-alarm probability of 10-3, (From J. 
 Brian D. Rigling, Flying blind: A challenge problem for SAR imaging without navigational data. In Proceedings of the SPIE, Baltimore, MD, USA, 2–3 May 2012; Volume 8394. 
 DARDIZED POINT TARGETS 4HE )-/ PERFORMANCE STANDARDS RECOGNIZE THAT THE DETECTION PERFORMANCE OF RADARS WORKING WITHIN CONDITIONS OF CLUTTER WILL NOT NECESSARILY GIVE  THE PERFORMANCE DEFINED FOR CLEAR CONDITIONS -ANUFACTURERS ARE REQUIRED TO PROVIDE  EFFECTIVE MANUAL AND AUTOMATIC ANTI 
 TO 
 The Geodynamics Experimental Ocean Satellite (GEOS-3) was a remote-sensing satellite that contained five instruments in the experiment package.19"21 These were (1) an SBR altimeter, (2) two C-band transponders, (3) an S-band transponder, (4) laser retroreflectors, and (5) a radio doppler system. The purpose of the GEOS-3 satellite was to perform experiments in support of the application of geodetic satellite techniques to geoscience investigations such as earth physics and oceanography. The SBR altimeter mission objective on the GEOS-3 satellite was to perform an in-orbit experiment that (1) determined the feasibility and utility of a space-borne radar altimeter to map the topography of the ocean surface with an absolute accuracy of ±5 m and with a relative accuracy of 1 to 2 m, (2) determined the feasibility of measuring waveheight, (3) deter- mined the feasibility of measuring the deflection of the vertical at sea, and (4) contributed to the technology leading to a future operational altimeter satellite system with a 10-cm measurement capability. 
 Generally, the MTI improve - ment factor that can be obtained with a magnetron is not as good as can be obtained  with a linear-beam amplifier. In the past, there might have been debate as to whether to use an oscillator or an  amplifier for a high-performance radar transmitter. There is usually no question that  the amplifier is usually the preferred choice, except in situations where the low cost of  a magnetron transmitter is more important than the lower MTI improvement factor it  provides compared to a linear-beam transmitter. 
 Proudler, A. Farina, and J. G. 
 In such an approach, performance is improved when the beam scans a small amount in angle between transmissions. As the beam steps past the target in elevation, it is possible to display intensity, or target echo strength, on a display or other indicator at the angular locations of the beam. A centroidal interpolation of the angular locations as weighted by the receive pulse amplitudes may be used to extract the target angle estimate. 
 A tracking radar must also be designed for good angular accuracy. Good angle accuracy is achieved with nar- row beamwidths (large G,) and with high ElN0 (large Ae). Thus a large Gt Ae prod- uct is consistent with good tracking accuracy as well as good detectability. 
 65D, pp. 101-1 10, 1961.  340I0<TRODUCT10N TORADAR SYSTEMS 72.Wheeler, H.A.:ASystematic Approach totheDesignofaRadialOr Element foraPhased-Array Antenna, Proc.IEEE,voL56,·pp.1940-1951, November, 196~. 
 2, Ferrite Phasers and Ferrite MIC Com­ ponents," Artech House, Inc., Dedham, Mass .. 1974.  (A collection of reprints of pap'ers covering toroidal waveguide phase shifters, dual-mode phase  shifters. 
 The  relative amplitudes of the three echoes are in the ratio of 1, 2p and p2, where p = surface  reflection coefficient. A measurement of the time delay tn along with the range R to the target  and knowledge of the height h, of the radar antenna yields the height of the target. This  technique works best over surfaces with large reflection coefficient, and when the pulse widths  Figure 14.11 Idealized echo response of a point target  located above a reflecting surface, for the case where  the pulse width is less than the time separation t, be-  tween the direct and surface-reflected signals. 
  +)%  (" - * (     '+"*%( % %$ %," $   *  *-%%,") -  $      $*    *"  )%$*  ) " $    .* $  /%$*     $*    *"  )%$*  ) " $    .* $  /%$*          . 
 GETS THAT ATTEMPT TO USE TERRAIN 
 The amount of isolation which can  be readily achieved between the arms of practical hybrid junctions such as the magic-T, rat  race, or short-slot coupler is of the order of 20 to 30 dB. In some instances, when extreme  precision is exercised, an isolation of perhaps 60 dB or more might be achieved. One limitation  of the hybrid junction is the 6-dB loss in overall performance which results from the inherent  waste of half the transmitted power and half the received signal power. 
 Venera-8  carried a pulse-modulated radar altimeter, which  returned 35 readings during its descent from orbit to its demise on the surface of Venus.  FIGURE 18.13  The CryoSat satellite and its SIRAL altimeter: The  two antennas (Interferometric mode) are athwart the velocity vector,  so that the differential phase (modulo 2 p  ) of the first return indicates  the cross-track position of the minimum-range reflecting surface,  which, in effect, is a measure of the cross-track component of the  mean surface gradient. ( Courtesy of European Space Agency ) ch18.indd   43 12/19/07   5:15:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
    
 UP OR EVEN AN UNDERSTANDING OF  WHY RADAR INFORMA 
 Development of three-dimensional bistatic coordinate systems for some applications is available elsewhere.16'46'48'75'76 A useful relationship is that the bisector of the bistatic angle is orthogonal to BASELINE = L FIG. 25.1 Bistatic radar north coordinate system for two dimensions.73TANGENT TOISORANGE CONTOUR TARGET . the tangent of an ellipse with foci at the transmitter and receiver sites and passing through the target position. 
 W. Bauchman, and W. Binnian: 3- and 9-Centimeter Propagation in Low Ocean Ducts,  Proc. 
 SQUAREDDISTRI IBUTIONWITH DEGRESSOFFREEDOM PDI. 
 142 146.  January, 195.l  71. Beard, C. 
 MIL-5, pp. 80-94, April, 1961.  17. 
 The input voltage is increased from V1 to V1 + 3 or 6 dB, changing the operating point from A to B. The frequency is now changed in both directions to find those two frequencies that place the operating point at C. The same result also may be obtained by changing the frequency until the output is reduced by 35 or 65, where S is the volts-per-decibel characteristic. 
 Cramp, and K. Curtis: Experimental Study of the Radar Cross-Section or  Maritime Targets, IEE (London) Journal on Electronic Circuits a11d Systems, vol. 2, no. 
 ZERO IMAGINARY COMPONENT OF THE INDEX OF REFRACTION  THE 2#3 OF THE SPHERE DECAYS  GRADUALLY WITH INCREASING ELECTRICAL SIZE !TLAS ET AL WENT EVEN FURTHER BY COMPARING  THE MEASURED AND THEORETICAL 2#3 OF 0LEXIGLAS SPHERES IN THEIR ATTEMPTS TO UNDERSTAND THE SCATTERING BY HAILSTONES  4HE 2#3 OF VERY SLENDER DIELECTRIC BODIES DOES NOT EXHIBIT THIS COMPLEXITY  HOW 
 The request for a low sidelobe level  has to be traded off with the corresponding degradation of the main-beam width;  the widening of the main-beam width may make the radar more vulnerable to main- beam jamming. The noise jammer situation is basically an energy battle between the radar and the  jammer. In the main-beam noise-jamming situation, the advantage is with the jammer  because the radar experiences a two-way propagation loss of its energy as contrasted  with the one-way propagation loss between the jammer and the radar. 
 Equipment Group, August, 1976. 57.Skolnik, M.I.:AnAnalysis ofBistaticRadar,JRETrailS.,vol.ANE-~. pp.1927.March.1961. 
 SIN  P    AND THE PATTERN IS   %%.S .SE   SIN    SIN SIN    PPPP 
 1551–1552. 40. D. 
 Ifautomatic detection, sidelobe cancellation, o"r"MTfisneede(J'J'f}Ine--ta<nrr;-these mustb"e-separately employed ineachreceiving channel, thusaddingtothecostandcomplexity oftheradar.Theindividual pencilbeams,however, limitthevolumeofspaceobserved, whichcanbeanadvantage inrainclutterorchaff.The MTIinthelowerbeamscanbeoptimized forsurfaceclutterandMTIintheupperbeams,if usedatall,canbeoptimized forrainandchaff.Theindividual pencilbeamshaveahighergain thanafan-beam antenna, andcanprovide alargernumberofhitsatahigherdataratethan cana3Dradarwithasinglescanning beaminelevation. Scanning pencilbeam.Three-coordinate, or3D,information canbeobtained oneachrotation oftheradarbyelectronically scanning asinglepencilbeaminelevation whilemechanically rotating theantenna inazimuth. Thebeam...israpidlyscanned through q.l.C~.en'tireelevation coverage inthetimetheantenna rotates9ne.._azim~. 
 Iri practice, a compromise value of q between  0.5 arid 0.6 is ofteri selected, corresponding to plate spacings of0.557A and 0.625A and to power  rcllcctioris ;it riorrn;~l iricidericc of 1 1 arid 6.25 percent, respectively (Ref. 1, p. 410). 
 The output of coherent radar is the output of a synchronous demodulator rather than that of an envelope detector commonly used in radars. The output is bipolar video, in which a reference bias level corresponds to zero level of video output. Storage and Recording. 
 TO 
 AP-22, pp. 295-302, March, 1974.  39. 
 I,  PP 11 38. July. 1964. 
 Variants of this system were sold by General Electric to the North Atlantic Treaty Organization (NATO) as the GE-592 and to the U.S. Air Force as the AN/ FIG. 5.12 AN/TPS-59 transmitter amplifier module. 
 EXTRACTION OFINFORMATION ANDWAVEFORM DESIGN439 J2.llelcy,(j.W.:Wavcform Design.chap.3of"RadarHandbook," M,LSkolnik (cd.);McUraw-llill HookCompany, NewYork,197U. 13.Sinsky.A.L.andCP.Wang:Standardization oftheDefinition oftheRadarAmbiguity Function, IEEETraIlS..Vol.AES-IO, pp.5J2513,July,1974. 14Dicke.R.II.:ObjectDetection Systcm. 
 91. J. N. 
 The scenario si gnals are passed through the following si m- ple signal processing.   LP A/D LOG CFARvideo signal  Figure 12.7  Signal processing chain for CFAR comparison (low -pass filter (LP), analog -to- digital converter (A/D) including magnitude calculation, loga rithmic amplifier  (LOG) and CFAR algorithm.   Figures 12.8- 12.13 show a modeled sea target scenario after the LOG -process with p otential  CFAR thresholds for CAGO - (Figure 12.8), OS - (Figure 12.9), CASH - (Figure 12.10), CA-   (Figure 12.11), CAOS-  (Figure 12.12) and MAMIS - (Figure 12.13) CFAR. 
 IEEE Trnrts.. vol. AP-18. 
 DWELL STAGGERING IS PREF 
 D. Pidhayny of the Aerospace  Corporation.) . 180 INTRODUCTION TO RADAR SYSTEMS  Precision "on-axis" tracking.62-65 Some of the most precise tracking radars are those asso­ ciated with the instrumentation used at missile-testing ranges.62 One such class of precision  tracking radar has been called on-axis tracking.63 The output of a conventional sl!rvo system  lags its input. 
  
 This requirement is readily satisfied for short interopportunity intervals, such  ch18.indd   26 12/19/07   5:14:43 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 Athree-fold indication scheme isused. One indicator gives the general PPI picture and asecond gives anexpansion inrange and azimuth angle which enables detailed control tobeaccomplished. The third indicator isarange-height indicator. 
 The composite surface model, in which the sea is recognized as  composed of a number of waves of different wavelengths and amplitudes, has been more  successful than previous models for describing the mechanism of sea ~lutter.'~~~~~' la It is based  on the application of classical scattering theory to a "slightly rough surface" which is  described by the mean-squared-height spectrum of the sea surface. (By a slightly rough surface li  is meant one whose height variations are small compared to the radar wavelength and whose  slopes are small with respect to unity.) The resultant radar backscatter can be interpreted as  that obtained from the component of the sea spectrum which is "resonant" with the radar  wavelength. That is, the radar wavelength A, is related to the water wavelength A, by the  relation  I, = 2A, cos 4 (13.13)  where 4 = grazing angle. 
 ERN SEAS COATED WITH ICE BECAUSE RADAR CAN TELL WHICH TYPES OF ICE ARE EASIER FOR A SHIP TO PENETRATE !IR 
 8 19-828, November, 1976.  53, dcloor. G. 
 Itrequires largebandwidth withthe possibility forinterference tootherusersoftheband.Theshorterthepulsethemoreinforma­ tionthereisavailable fromtheradar,andtherefore thegreaterwillbethedemands onthe information processing anddisplay.Insomehigh-resolution radarsthenumberofresolution cellsmight"egreaterthanthecapability ofconventional displays topresenttheinformation withoutoverlap, sothatacollapsing losscanresult.Thewidebandwidth mightalsomeanless dynamic rangeinsomeradardesigns.Iftheradartransmitter ispeak-power limited, the shorterthepulsethelesstheenergytransmitted. Thishasresulted inshort-pulse radars llsuallybeinglimitedinrange. Pulsecompression isamethodforachieving mostofthebenefitsofashortpulsewhile keepingwithinthepractical constraints ofthepeak~power limitation. 
 Two basic monopulse systems, phase comparison and amplitude comparison, are illustrated in Fig. 6.19. The amplitude system is far more prevalent in radar antennas, using the sum of the two feed outputs to form a high-gain, low-sidelobe beam, and the difference to form a precise, deep null at boresight. 
 The most capable of these configurations is the CW tracking illuminator. It is generally a two-dish radar because sufficient receiver-transmitter isolation cannot usually be achieved in a single-dish system. The CW tracking illuminator, since it uses the same radar signal to track the target as the missile utilizes for homing, sees essentially the same view of the target environment and can track targets at the same low altitudes as the missile seeker. 
 Noise can enter the receiver via the antenna terminals along with the desired signals, or it  might be generated within the receiver itself. At the microwave frequencies usually used for  radar. the external noise which enters via the antenna is generally quite low so that the receiver  sensitivity is usually set by the internal noise generated within the receiver. 
    PP n    3 4ANG AND / ( 3HEMDIN  h-EASUREMENT OF HIGH 
 2058–2074, 2005. 61. S. 
 C. Hansen; John Wiley & Sons Publication;      ISBN  0-471-53076- X  − Phased Array Antenna Handbook; Robert J. Mailloux; Artech House Inc.;      ISBN  0-89006- 502-0  − Practical Phased Array Antenna Systems; Eli Brookner; Artech House Publishers;   ISBN 0- 89006- 563-2  − Antennas for Radar and Communications - A Polarimetric Approach; Harold Mott;  John Wiley & Sons; ISBN 0 -471-57538- 0  15.6 RCS   − Radar Cross Section Handbook Vol. 
 30, 1973.  7. Macdonald, F. 
 Aseparate setoffiltersisrequired foreachrangegate.Aconsequence ofthehigh prfofthepulsedoppler radaristhattherearefewerrangegatessothatfewersetsoffilter­ banksareneeded.Insomepulse-doppler radars,thedutyfactormightbeashighas0.3to0.5 sothatonlyonesctoffIltcrsisneeded.Suchahigh-duty factorradarissometimes called iJllerntl'ted CW.orICW. Noncoherent AMTI.Thenoncoherent MTIprinciple thatusestheclutterechoinsteadofa cohoasthereference signalcanalsobeappliedtoaradaronamovingplatform. Although itis attractive foroperation inaircraftwherespaceandweightmustbekepttoaminimum, its MTIperformance islimited,asisitsground-based counterpart, bythelackofspectralpurity oftheclutterwhenusedasareference signal,andbythespatialinhomogeneity (orpatchiness) ofthec1uller. 
 We can regulate sensitivity by another means. The  control of anode voltage affects sensitivity—in fact,  sensitivity.and voltage on ‘the final anode are almost in  direct proportion. A rough-and-ready method of appre-  Ciating this point is to visualize that as the anode voltage  is raised the electrons are pulled ‘harder’ from the  cathode; the beam is thus more intense and more diffi-  cult to deflect from its normal path. 
 $IGITAL #ONVERTER &ULL 3CALE  4HE !$ CONVERTER FULL SCALE LEVEL DETER 
 There is no simple formula or step-by-step guide for the design of an air-surveillance  radar. One place to start, however, is with the proper form of the radar eqi~ation, along with a  clear understanding of the task to be accomplished by the radar and knowledge of the con-  straints imposed by the environment. Quite often there IS more than one Pictor affcct~ng the  selection of a particular radar characteristic, and these factors are sometimes conllicting. 
 This implies that the transmitted signal ener_gy is the same  with or without weighting, as follows from the discussion in Sec. 10.2 of the output signal-to­ noise ratio of a matched filter. However, when the transmitter is peak-power limited, it is  preferable to use a constant-amplitude transmitted signal and perform the weighting in the  receiver, in spite of the mismatched filter with its reduction in signal-to-noise ratio.25 In one  example,24 transmitting a linear-FM waveform with a gaussian envelope and a matched-filter  receiver to give -40 dB sidelobes resulted in 2.2 dB greater penalty in detection capability  than when a uniform amplitude is transmitted with Hamming weighting on receive in a  mismatched filter. 
 granted Nov. 77. 1934, to A. 
 )) SPACECRAFT  4HE RADAR DRIVES THE CONICALLY SCANNED REFLECTOR ANTENNA  WHICH TAKES UP MOST OF THE REAL ESTATE ON THE %ARTH 
 There arc also sevaal  techniques found in radars for the detection of targets in clutter whose purpose is to prevent  the clutter from saturating the display or the receiver, or to maintain a constant false-alarm  rate (CF AR). They have no subclutter visibility in that they offer no ability to see targets  masked by clutter, but they do permit targets large compared to the clutter to be detected that  might otherwise be lost because of the limited dynamic range of the receiving system. An \ l . 
 Then the signal-to-noise ratio (SNR) is  SNRLossTx-avg= =P G R kT F Vr2 3 0 3 3 0 2 4λ σ δ π ψ ( ) ( ) cosP P A R k T F Vr Tx-avg Loss2 2 0 3 0 8η σ δ π λ ψ ( ) cos (17.32) This agrees with Skolnik,21 Eq. 14.15, and Curlander et al.,4 Eq. 2.88. 
 2011 ,181, 699–715. [ CrossRef ] 17. Nguyen, L.H.; Tran, T.D. 
 F., and G. T. Coate: "Principles of Radar," McGraw-Hill Book Co., New York, 1952. 
 Frequent indications that the antenna sys - tem is functioning or is capable of functioning should be available. In one possible  method, the phase shifters are programmed to focus on a nearby monitor probe and  scan past it.21 This will yield a close approximation of the complete radiation pattern,  where gain and sidelobes can be measured and compared with previous results. The  combination of individual elements and their phase shifters (and drivers) can also be  checked with this configuration. 
 For this reason, a low IF generally provides better suppression  of spurious responses. The spurious-effects chart also demonstrates spurious input responses. One of the  stronger of these occurs at point B, where the 2 H – 2L product causes a mixer output in  the IF passband with an input frequency at 0.815. 
 ch19.indd   1 12/20/07   5:37:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 
 Over sea the kindred ASV en-  ables the operator to see, as though plotted on a  . THE MAGIC EYE 143  chart, the positions of all ships and coastlines within  range.  It gives us, at best, the sort of chart referred to in  The Hunting of the Snark, the chart  ... 
 LOOP TRACKER IS USED TO POSITION RANGE AND VELOCITY GATES AROUND THE ALTITUDE RETURN AND BLANK THE AFFECTED RANGE 
 PASS TECHNIQUES ARE WELL SUITED TO MAPPING TOPOGRAPHIC RELIEF AND TO LONG 
 The gain ofthei-famplifier isadjusted byvarying thevoltage onthe grid ofthesecond and third stages bymeans ofanexternal control. The receiver can betuned either manually bymeans ofanexternal potentiometer, orautomatically bymeans ofa5-tube .\FC circuit. The AFC circuit isofthe hunt-lock type briefly described inSec. 
 The radar cross  section of the thin rod (and similar: objects) is small when viewed end-on (0 = 0°) since the  physical area is small. However, at near end-on, waves couple onto the scatterer which travel . 16  E 11.5  0 ::,  CT V, I 0 7 -I CV > I 0 I .0  0 I  0 2 -l QJ  L. 
  
  
 An equivalent circuit that accounts forthe r-fproperties isshown in Fig. 11.21. The nonlinear resistance oftherectifying contact isdenoted byr.. 
 TRACK AFTER 7 "ATH Ú )%%  . Ç°{n  2!$!2 (!.$"//+  7HEN THE PROBABILITY OF DETECTION IS MUCH LESS THAN UNITY  THE MEASUREMENT 
 57, pp. 324-335. March, 1969. 
 Devices that operate for short-pulse and low-duty-cycle applications, such as DME (distance- measuring equipment), Tacan, and IFF (identification, friend or foe) sys- tems, differ in design from the devices that have been designed for the longer pulse widths and moderate-duty-cycle waveforms that are more typical for surveillance radars. Very high duty cycles or CW operation dictates careful thermal design. An illustration of the thermal-time-constant effect, as it re- lates to a train of RF pulses, is shown in Fig. 
 Ruze, J.: The Effect of Aperture Errors on the Antenna Radiation Pattern, Suppl. al Num,o cimento,  vol. 9, no. 
 KAOAK .I'KANSMI.II'EKS 209  'I'llc crossed-field arliplificr is based 011 tllc sarlie i>riticiplc of clcctro~iic i~ltcractiori as tlic  magnetron. Thus, its characterist-ics resemble tliose of the magnetron,-and many CFAs are  cveli similar in physical appearance to a magnetron. The CFA also resembles the traveling-  wave tube because tlie electronic iriteractiori in both is wit11 a traveling-wave. 
 The received data must be compensated to offset the doppler shift, which varies   ch18.indd   57 12/19/07   5:15:19 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Space-Based Remote Sensing Radars. 
 83, no. 5, pp. 1065–1078, 2003. 
 Such asweep need notdissipate much power since theaverage current islow, but unfortunately thesame power supply isused onhigh– duty–ratio sweeps where the average current ishigh. The total power dissipation due tothe sweep circuit can beminimized byusing alarge number ofturns onthedeflecting coil and acorrespondingly high supply voltage, since this reduces thelosses inthedriver tube and inthepower supply itself. Usually, however, other circuits derive their power from thesame supply, and ahigh voltage results inunnecessary dissipation in them. 
 AES-10, pp. 574-582, September 1974. 26. 
 12.8). The automatic gain control isactuated bythesynchronization pulses. Asmall signal istaken from the plate ofthe final cathode follower, amplified, and passed toanother cathode follower. 
 Ground-Based Radars (AN/TPS-59, AN/FPS-117, and AN/TPS-77).  Lock- heed Martin’s long-range, solid-state 3D radar systems (see Figure 13.44) operate  at L band between 1.2–1.4 GHz. These systems provide position data for en-route  tracking of commercial aircraft, air surveillance/air defense, navigational assistance,  tactical control, and tactical ballistic missile (TBM) defense. 
 cc¯\  \      WHERE (F     COMBINED RESPONSE OF RECEIVER AND DOPPLER FILTERS  NORMALIZED TO  D"  NOISE GAIN  ,g F    PHASE NOISE AFTER DOWNCONVERSION AS DEFINED IN %Q &)'52%  0HASE NOISE COMPONENTS+ *. ( 1$("& $    ( # , )$,   2 2 %2 %2 %2 2)'')(# , )$, ! ( )'')(# , )$, !# , )$,  !- +) 0( )(/ +,$)(!          
 Left-hand diagrams in (a-c) are in polar coor­ dinates; right-hand diagrams are in rectangular coordinates. (a) Overlapping antenna patterns; (b) sum  pattern; {c) difTerence pattern; (d) product (error) signal.  an error signal whose magnitude is proportional to the angular error and whose sign is  proportional to the direction. 
 SCATTERED  SPECULAR DIRECTION  E   n  PI   PS  THAN ELSEWHERE AND MAY  IN SOME CASES  REDUCE ADVANTAGES OF THE  ENHANCED  FORWARD 
   HAS A SUBSONIC AIRFRAME 4HIS SUGGESTS THAT ALTHOUGH THE CHINE CONCEPT MAY HAVE WORKED FOR THE FUSE 
 ING A COOL  MOIST LAYER OF AIR OFTEN CALLED THE MARINE BOUNDARY LAYER &)'52%  %VAPORATION DUCT  
 CRAFT AND BALLISTIC MISSILES WITH THE IONOSPHERIC PLASMA n &URTHER  THE WAVELENGTHS  USED ARE OF THE SAME ORDER AS OCEAN SURFACE GRAVITY WAVES  AND THIS CORRESPONDENCE CAN BE EXPLOITED TO PROVIDE INFORMATION ON THE WAVE DIRECTIONAL SPECTRUM  OCEAN CURRENTS  AND  BY INFERENCE  SURFACE WINDS  )NDEED  SCATTERING FROM THE SEA CAN OFTEN BE EMPLOYED  AS A RADAR CROSS SECTION 2#3  AMPLITUDE REFERENCE AND IS A WID ELY USED DIAGNOSTIC TOOL  4HE NARROW 
 4.11 MTI FROM A MOVING PLATFORM  When the radar itself is in motion, as when mounted on a ship or an aircraft, the detection of a  moving target in the presence of clutter is more difficult than if the radar were stationary. The  doppler frequency shift of the clutter is no longer at de. It varies with the speed of the radar  platform, the direction of the antenna in azimuth, and the cl.evation angle to the clutter. 
   
     . 
 When noise jamming is present, the appearance or nonappear­ ance of the range rings can be.made to be a function of azimuth as well as range. RECEIVERS, DISPLAYS, AND DUPLEXERS 347  In making a measurement of the receivernoise-figure, the noise source or signal generator  is usually inserted by a directional coupler ahead of the duplexer and other RF components so  that the overall noise-figure of the system is measured rather than that of the receiver alone.  9.3 l\tlXERS  Many radar superheterodyne receivers do not employ a low-noise RF amplifier. 
 (11.12)   The explicit formulation of Equation (11.12) introduces the formal coefficients cij:  € Svvm−c10 Svvm−c20 Svvm−c30 Svvm−c40                  =M vv Mhh Mvh Mhv                  =c 11c12c13c14 c21c22c23c24 c31c32c33c34 c41c42c43c44                  S vvc Shhc Svhc Shvc                   (11.13)  These coefficients will be referred to as error coefficients in the coming sections.  The four  additive coefficients cio are identical with Iξη and contain the isolation error and the room  reflection.  The 16 terms of cij result from the transfer coefficients Tξη und Rξη. 
 1419. 67. R. 
 POLARIZED NOISE OR REPEATER JAMMERS  )N THE SECOND USE OF POLARIZATION  THE RADAR ANTENNA SYSTEM PURPOSELY RECEIVES  THE CROSS 
 Poulton: High-Efficiency Microwave Reflector Antennas-A Review,  Proc. IEEE. vol. 
 Monopulse is the technique of choice to determine  the target angular coordinates when ECM is encountered since it is much harder to  deceive than a conical scan. However, the application of adaptive beamforming (to bet - ter mitigate the presence of an intense jammer) with the related distortion of sum and  difference beam shapes may introduce errors in the conventional monopulse technique,  in particular, if the jammer is close to the main beam105; thus, the conventional mono - pulse technique cannot be applied.106 A Maximum Likelihood (ML) approach for target  DoA estimation is considered, which generalizes the monopulse concept.107–114,104 ch24.indd   23 12/19/07   6:00:39 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 If it is necessary to preserve the shape of the input  pulse rather than maximize the output signal-to-noise ratio, some other criterion must be  employed. 10  The output of the matched filter may be shown to b(: proportional to the input signal  cross-correlated with a replica of the transmitted signal, except for the time delay t 1• The  cross-correla,tion function R(t) of two signals y(,l) and s(,l ), each of finite duration, is defined as  R(t) = J 00  y(J.)s(J. -t) d). 
 XUY. at night Or I ClOUGQ——TluUW iseu wao uwre-  loped from early airborne radar—The har-  nessing of ground returns—The part Mr  Churchill played in H2S -development—  Description of the H2S system, its aerial  array, and method of scanning.  ELECTRONIC NAVIGATION  Gee, G-H, and Oboe—Why Gee is more  accurate than normal Df-ing by radio—How  the Gee grid is built up—Simple explanation  _ of the Gee system—How Loran was de-  veloped from Gee—How Oboe works—A  responsor system, working from ‘cat’ and  ‘mouse’ stations—The development of G-H  from Gee and Oboe—Peacetime uses of these  beacon systems. 
 *UNE   * - 3TURM AND * # 7EST  h.UMERICAL STUDY OF SHADOWING IN ELECTROMAGNETIC SCATTERING  FROM ROUGH DIELECTRIC SURFACES v  )%%% 4RAN IN 'EOSCI AND 2EMOTE 3ENSING   VOL   NO    3EPTEMBER   2 " 0ERRY AND ' 2 3CHIMKE  h,ARGE 
 BAND RADAR v 'OODYEAR !EROSPACE #ORPORATION   '%2! 
 Figure 16.27 shows . MOTION - WAVELENGTHS/INTERPULSE PERIOD FIG. 16.26 Adapted and unadapted improvement factor as a function of normal- ized antenna motion per interpulse period; 16-element (half-wavelength spacing), two-pulse space-time adaptive processor; antenna array aligned to the ground track. 
 CW radar is also employed for monitorln  the docking speed of large ships. It nas also seen application for intruder alarms and for th  measurement of the velocity of missiles, ammunition, and baseballs.  The principal advantage of a CW doppler radar over other (nonradar) methods of meas-  uring speed is that there need not be any physical contact with the object whose speed is be~ng  measured. 
 ABLE SOLUTION 4HE !2%03 GRAPHICAL USER INTERFACE WAS CREATED A ND INTERFACED TO THE  !0- TO PROVIDE THE USER AN END 
 IBLE IMAGERY 4HEREFORE  UPON SEEING  A 3!2 IMAGE  WE MAY INSTINCTIVELY ASSUME THAT  IT HAS CERTAIN PROPERTIES OF A VISIBLE IMAGE  WHICH  IN FACT  IT DOES NOT POSSESS /PTICAL IMAGERY IS BASED ON AN hANGLE 
 The latter are created by using the harmonics of a step-recovery diode multiplier. The signal coming from the phase detector is filtered to remove microwave frequencies and is then amplified in a low-noise baseband amplifier. The resulting phase noise can be measured by any of a variety of methods, including spectrum analyzers and analog wave analyzers. 
 E. N. Davies, “Use of bistatic radar techniques to improve resolution in the vertical plane,”  IEE Electron. 
 MINED BY WHAT THE RADAR SYSTEM DESIGNER THINKS THE BUYER OR CUSTOMER  OF THE RADAR DESIRES 3OMETIMES THE BUYER WILL ACTUALLY SPECIFY THE TYPE OF TRANSMITTER TO BE DELIVERED -ANUFACTURING A PRODUCT BASED ON WHAT THE BUYER THINKS HE OR SHE WANTS MAY BE A GOOD MARKETING STRATEGY FOR MANY PRODUCTS  BUT IN SOMETHING LIKE A RADAR  IT MIGHT BE BETTER FOR A CUSTOMER TO CLEARLY SPECIFY WHAT PERFORMANCE IS WANTED AND THEN LEAVE THE DECISION AS TO WHAT 2& POWER SOURCE SHOULD BE USED TO THE RADAR SYSTEM DESIGNER )T IS USUALLY BETTER IF THE RADAR DESIGN CAN BE DETERMINED BY THE RADAR SYSTEM DESIGNER AND NOT BY THE MANUFACTURERS MARKETING DEPARTMENT 4HE GOALS OF THE RADAR DESIGNER AND THE MARKET 
 During thegeneral advance inradar technique, the setwent through many detailed changes and improvements and was still inactive useattheclose ofthe Japanese war. The SCR-2701 and theCXAM arequite similar intheir operating fea- tures. The SCR-270 operates atafrequency of106 Me/see, has apeak power of100 kw, apulsewidth from 10to25psec, and areliable range against single bombing aircraft ofmore than 100 miles. 
 -Ê"Ê 
 Since aircraft targets usually  move several resolution cells from one scan to the next, it is unlikely that the reference  samples will be contaminated by a target return. Alternatively, by making the averag - ing time (in terms of past scans) long, the effect of an occasional target return can be  minimized. Although the primary purpose of the clutter map is to prevent false alarms  due to discrete clutter or clutter residues that are at a fixed location, it may also be  necessary to consider slowly moving point clutter in the clutter map design, either to  suppress bird returns or because the radar is on a moving platform (e.g., a ship). 
 SCAN CORRELATION IS MADE ON THE DETECTIONS THAT UPDATE THE TRACK FILES !LTHOUGH TRACKING ACCURACIES ARE LESS THAN CAN BE ACHIEVED IN A DEDICATED SINGLE 
 £x°£ä  2!$!2 (!.$"//+  'ENERAL 4RENDS  "EING THE FIRST REALLY COMPREHENSIVE COLLECTION OF CLUTTER DATA  OVER A WIDE RANGE OF RADAR FREQUENCIES  THE &2 PROGRAM PRODUCED MANY PLOTS SHOW 
  3!2 MODES DEVELOPMENT AND  UTILIZATION v #ANADIAN *OUR OF 2EM 3ENS  VOL   PP n    ( 7AKABAYASHI ET AL  h!IRBORNE , 
 97-109, 1928.  61. Pannell, J. 
 Ingeneral, because ofdifferences inthe effective inductance and capacity ofthe FIG.108.-Distribution ofr-ffields andcharges inahole-and-slot anode block oscillating intheT/2anode. oscillating circuits, each ofthese modes has adifferent frequency of oscillation. One ofthe objectives ofmagnetron design istoarrange. 
 On receive, the array is made adaptive by obtaining a separate  output from each element. Each element output can be weighted separately and the outputs  added together to form an aperture illumination function that adaptively permits motion or  the antenna phase center so as to compensate for platform motion. Adaptive loops are also  used in the delay-line canceler to control the doppler response of the canceler as well as the  antenna angular response. 
 TH ELEMENTARY RADIATOR BELONGS TO THE  J 
 7.7), the  gain as a function of elevation angle is given by  G(<J,) = G(</>o) csc2 <P  csc2 <Po (2.46)  where G( <J,) gain at elevation angle <J,, and <Po and <Pm are the angular limits between which the  beam follows a csc2 shape. This applies to the airborne search radar observing ground targets  as well as ground-based radars observing aircraft targets. (In the airborne case, the angle</> is the  depression angle.) From <J, = 0 to <J, =<Po, the antenna pattern is similar to a normal antenna  pattern. 
 59.Mallett, J.D.,andL.E.Brennan: Cumulative Probability ofDetection forTargets Approaching a Uniformly Scanning SearchRadar,Proc.IEEE,vol.51,596-601, April,1963,andvol.52,pp.708-709, June,1964. 60.Johnson, J.B.:Thermal Agitation ofElectricity inConductors, Phys.Rev.,vol.32,pp.97-109,1928. 61.Pannell, J.H.,J.Rheinstein, andA.F.Smith:RadarScattering fromaConducting Cone-Sphere, MITLincolnLaboratory Tech.Rept.no.349,Mar.2,1964. 
 It took almost twenty years for the full capabilities offered by MTI signal-processing theory to  be converted into practical and economical radar equipment. The chief factor that made this  possible was the introduction of reliable. small, and inexpensive digital processing hardware. 
 tiowever. it is possible to modify the antenna pattern to radiate more energy at higher angles.  One teclitlique for accomplishing this is to employ a fan beam with a shape proportional to the  square of the cosecant of the elevation angle. 
 PGIT-4, pp. 171-212, September, 1954.  25. 
 The range gates  are activated once each pulse-repetition interval. The output for a stationary target is a series  of pulses of constant amplitude. An echo from a moving target produces a series of pulses  which vary in amplitude according to the doppler frequency. 
 These are then fed back to the transmitter  in such a manner as to reduce the original frequency de~iation.~' It has been said69 that  experience indicates that a satisfactory measurement of AM noise over the doppler frequency  band provides assurance that both AM and FM noise generated by the tube are within  required limits.  The transmitter noise that enters the radar receiver via backscatter from the clutter is  sometimes called transmitted clutter.69 It can appear at the same frequencies as the doppler  shifts from moving targets and can mask desired targets or cause spurious responses. This  extraneous noise is produced by ion oscillations in the tube (usually a klystron amplifier)  rather than by the thermal noise, or noise figure. 
 Cox, and D. Wilksch, “Tactical data link systems and the Australian defense  force (ADF)-technology developments and interoperability issues,” Defense Science and  Technology Organisation Report, DSTO-TR-1470, approved for public release. 81. 
 MAP MODE  THE (* 
 68.Williams, P.D.L.,H.D.Cramp,andK.Curtis:Experimental StudyoftheRadarCross-Section of Maritime Targets,lEE(Lolldon) JournalonElectronic CircuitsandSystems, vol.2,no.4,pp.121-136, July,1978. 69.Varela,A.A.:TheOperator FactorConcept, ItsHistoryandPresent Status,Symposium onRadar Detection Theory,ONRSymposium ReportACR-IO, Mar.1-2,1956,DOCNo.117533.. CHAPTER  THREE  AND FREQUENCY-MODULATED RADAR  3.1 THE DOPPLER EFFECT  A radar detects the presence of objects and locates their position in space by transmitting  electromagnetic energy and observing the returned echo. 
 BORNE SCATTEROMETRY IS TO DESIGN THE RADAR SUCH THAT THE PRECISIONTHE NORMALIZED STANDARD DEVIATION OF THE R    MEASUREMENTSIS SUFFICIENTLY SMALL )N THE STANDARD TERMINOLOGY OF SCATTEROMETRY   THE CLASSICAL PARAMETER IS  +0  THE NORMALIZED STANDARD DEVIATION OF THE MEASUREMENT  )N THE CASE OF A FAN 
 TION  METEORS HAVE A STRONG DIURNAL VARIATION AND DIRECTIONALITY 4HEY ARE EVER 
 7.19 is an E-plane lens since the electric-field vector is parallel to  the plates. Snell's law is obeyed in an E-plane lens, and the direction of the rays through the  lens is governed by the usual optical laws involving the idex of refraction.  The surface contour of a metal-plate lens is, in general, not parabolic as in the case of the  refle~tor.~ For example, the surface closest to the feed is an ellipsoid of revolution if the sirrfact  at the opposite face of the lens is plane. 
 This is  the reason for the often used denomination , low noise preamplifier  (LNA).      Figure 21: E.g. a Didactical Primary Radar:  If the noise figure were the only issue one was trying to address in the design of a recei ver,  then placing as much gain as close to the beginning of the receive chain as possible is desired. 
 POSITION MODULATION 00-   OR PULSE 
 DENT ERRORS &OR EXAMPLE  A  n RMS PHASE ERROR WILL PRODUCE  AN RMS SIDELOBE LEVEL THAT  IS APPROXIMATELY  D" BELOW THE GAIN OF AN ELEMENT )F  ELEMENTS  D"  ARE USED  THE RMS SIDELOBE LEVEL IS  D" BELOW THE GAIN OF THE ARRAY 4HIS IS THE EFFECT OF ONLY THE RANDOM PHASE ERRORS 4HE EFFECTS DUE TO AMPLITUDE ERRORS AND FAILED ELEMENTS MUST ALSO BE INCLUDED 4HE PREVIOUS DISCUSSION APPLIES TO THE RMS SIDELOBE LEVEL 4HIS ANALYSIS HAS BEEN  EXTENDED BY !LLEN  TO APPLY THE PROBABILITY OF KEEPING A SINGLE SIDELOBE BELOW A GIVEN  &)'52%   2ANDOM ERRORS AND RMS SIDELOBES . £Î°ÎÓ  2!$!2 (!.$"//+  LEVEL AND THEN THE PROBABILITY OF KEEPING A NUMBER OF SIDELOBES BELOW A GIVEN LEVEL "Y  IGNORING THE ELEMENT PATTERN  THE -33, INCLUDING FAILED ELEMENTS IS GIVEN BY   -33, 
 Lett ., vol. 6, no. 1, p. 
 Andrews used the procedure to minimize the residue power  over the full antenna pattern, which includes the main-beam and sidelobe regions. ch03.indd   20 12/15/07   6:03:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Delaying the rel rans.mission causes the repeated signals to appear at a  range and/or azimuth different from that of the jammcr. Thus the signal from the repeater  generates a false target echo at the output of the radar receiver which, in principle, cannot be  distinguished from a real target. A rr11c re{'eater is one which retransmits the same signal that a  target would reradiate. 
 If this direct path signal is not attenuated, the received signal becomes masked in range  and often masked in doppler by sidelobes of the correlated direct path signal. Direct-path breakthrough effects are similar to those of a spot noise jammer and  can be characterized by an increase in the system noise temperature, Ts = Fn To, where  Fn is the receiver noise figure and To = 290 K. Specifically, the amount of increase in  Ts, and hence the amount of attenuation Cdp required to reduce the direct path signal  to the level of Ts, is  Cdp = PT GT (GR)T l 2 / (4p )2 B L2 (kTs) (23.21) where PT, GT, l, and k are defined with Eq. 
  HAVE BEEN ANALYZED TO ESTIMATE THE RATE OF MEAN SEA 
 RANDOM 
 IZED CHANGING SCENARIOS REPRESENT AN ATTRACTIVE TECHNICAL SOLUTION  3IMULATION IS ALWAYS OF VALUE HOWEVER  THE EFFECTIVENESS OF %#- AND %##- IS  ULTIMATELY DONE  WHEN POSSIBLE  WITH TESTS OF REAL %7 CAPABILITIES AGAINST REAL RADAR SYSTEMS UNDER REAL 
 Rutledge, V. Chandrasekar, E. A. 
 VIDED HIGH POWER WITH GOOD STABILITY)NSTALLATION FIRST LETTER 4YPE OF %QUIPMENT     SECOND LETTER  0URPOSE THIRD LETTER  ! 0ILOTED AIRCRAFT , #OUNTERMEASURES " "OMBING " 5NDERWATER MOBILE   SUBMARINE0 2ADAR $ $IRECTION FINDER  RECONNAISSANCE AND SURVEILLANCE $ 0ILOTLESS CARRIER 3 3PECIAL OR  COMBINATION' &IRE CONTROL & &IXED GROUND 7 !RMAMENT  PECULIAR TO ARMAMENT NOT OTHERWISE COVERED . .AVIGATION ' 'ENERAL GROUND USE 1 3PECIAL OR COMBINATION + !MPHIBIOUS 2 2ECEIVING - -OBILE GROUND  3 $ETECTINGRANGE AND  BEARING  SEARCH 0 0ORTABLE 4 4RANSMITTING 3 7ATER SHIP  7 !UTOMATIC FLIGHT OR REMOTE CONTROL 4 4RANSPORTABLE GROUND  8 )DENTIFICATION AND RECOGNITION 5 'ENERAL UTILITY 9 3URVEILLANCE AND CONTROL  BOTH FIRE CONTROL AND AIR CONTROL  6 6EHICULAR GROUND  7 7ATER SURFACE AND  UNDERWATER COMBINED : 0ILOTED 
 Only one beam  at a time will be radiated if the grating lobe relation of Eq. (8.21) is satisfied; else-multiple  beams. or grating lobes, will appear. 
 TIVE SURFACE RANGE RESOLUTION AT SHALLOWER INCIDENCE IS IMPROVED OVER THAT ACHIEVED AT STEEPER INCIDENCE &ORTUNATELY  AT STEEPER INCIDENCE  AND HENCE AT LONGER RANGES  THERE WAS MORE TIME AVAILABLE TO GATHER MORE LOOKS )MAGE 1UALITY  ,OOKS AND RESOLUTION WORK TOGETHER TO DETERMINE THE IMAGE QUAL 
 In atrackingradar,theangleandrangeerrorsintroduced byafinitesizetarget arereduced withincreased range-resolution sinceitpermitsindividual scattering centers toberesolved. Multipatl1 resolution. Sufficient range-resolution permitstheseparation ofthedesiredtarget echofromechoesthatarriveviascattering fromlongerpaths,ormultipath. 
 Steinmetz, “Amplitude and phase sensing monopulse system parameters,”  Microwave J ., pp. 27–33, October 1959. 38. 
 CM BAND )T IS COMMON FOR SHORT WAVELENGTH ON 
 Comparison of Production A.S.V. Mks. III and VI, C.C.D.U. 
 21, no. 5, pp. 415-432, September, 1977. 
    . 
 CALLED DIAGONAL LOADING   !DAPTIVE ARRAYS CAME ABOUT AFTER THE SUCCESSFUL APPLICATION OF  3,#  THE APPLICA 
 N. Ludington: A Charge Transfer Device MTI Implementation, IEEE 1975  lm,•rnotional Radar Co11ference Record, pp. 107-110, IEEE Publication 75 CHO 938-1 AES. 
 SIDED BANDWIDTHS OF  -(Z AND  -(Z  RESPECTIVELY  AND WITH POSITIVE 
 The answer to t hese challenges is the use of pulse  compression. If a pulse can be effectively compressed in time,  then the returns will no longer overlap. Pulse compression  allows low amplitude returns to be “pulled” out of the noise  floor. 
 , , . b , *,,  466INTRODUCTION TORADAR SYSTEMS affected byheatinmuchthesamemanner asthewhiteofanegg.Itistransparent atroom temperature butbecomes opaque ifitstemperature israisedexcessively. Theprocess isan irreversible one.Although thetestesareapparently morcsensitive toheatthantheeye, testicular damage isoftentemporary andreversible.63.65 Atfrequencies below400andabove3000MHz,thebodyabsorbs lessthanhalfthe incident energy. 
 13.4.3 This is a composite'  plot of experimental X-band data obtained at three different locations and at three different  times for a grazing angle of 10". (The data represented by the solid circles were obtained  in the Bermuda area; the x's in the North Atlantic; and the triangles, off Puerto Rico.)  The dashed curve in each figure is drawn as if all three sets of data were from a single  population. This curve is of the form exp (-c/U) where c is an arbitrary constant and U is  the wind speed. 
 The results veriﬁed their consistency. The second part of this paper presents a method to improve the topside proﬁle of the ionosonde with TEC retrieved from PolSAR data. The ionosonde station located in the scene of PolSAR was found. 
 SURFACE ! 
 If this is done, the restrictions which limited the maximum antenna length to that given by Eq. (21.12) are no longer pertinent and the new limitation on the length of the syn- thetic antenna achievable becomes simply the linear width of the radiated beam at the range of the target. In some cases, a resolution coarser than DII is sufficient. 
 Friis. H. T., and C. 
 The choice of the position of the auxiliary  antenna has an impact on SLB performance in presence, for instance, of multipath; to  avoid its effect, the phase centers of main and auxiliary antennas should be positioned  at the same height with respect to the terrain surface. In modern radar, the blanking of sidelobe impulsive interference may be achieved  by the comparison of signals, pertaining to the same cells of the range-filter map  (RFM) of main beam and SLB channels. The RFM is a two-dimensional map col - lecting the radar echoes of all range cells (after pulse compression) and all doppler  filters of a radar burst. 
 338-340, October, 1958.  6J. Hammer. 
 DOPPLER SPACE  UNMASKING TARGETS HITHERTO OBSCURED /FTEN SEVERAL WAVEFORMS WITH DIFFERENT REPETITION FREQUENCIES ARE INTERLEAVED TO ACHIEVE THIS &OR RADARS CLOSE TO THE AURORAL ZONE  THE OPTIONS ARE GENERALLY MORE LIMITED )ONOSPHERIC IRREGULARITIES THAT SCATTER BACK TO THE RADAR RECEIVER OCCUR MUCH MORE OFTEN  AT NIGHT THAN BY DAY AT ANY LATITUDE 3ENSIBLE SITING OF THE RADAR  ENSURING GOOD FRONT 
 TheN filtersgenerated bytheindexkconstitute thefilterbank.NotethattheweightsofEq.(4.13) andthediagram ofFig.4.11aresimilarinformtothephasedarrayantenna asdescribed in Sec.8.2. Theimpulse response ofthetransversal filterofFig.4.11withtheweights givenby Eq.(4.13)is N hk(t)=Lb[t-(i-1)T]e-j2rt(i-llkIN i"=I TheFourier transform oftheimpulse response isthefrequency response function NHlf)=e-j2rtflLej2rt(i-111fT-kiN! i"=1(4.14) (4.15) (4.16)Themagnitude ofthefrequency response function istheamplitude passband characteristic of thefilter.Therefore IH(f)I=If.ei2tr(i-IlffT-klNII =Isi~[nN(.fT-~LN)JI k. i=1 sm[n(fr-kiN)] Byanalogy tothediscussion ofthearrayantenna inSec.8.2,thepeakresponse ofthefilter occurswhenthedenominator ofEq.(4.16)iszero,orwhennUT-kiN)=0,n,2n,....For k=0,thepeakresponse ofthefilteroccursatf=0,liT,21T,...,whichdefines afilter centered atdc,theprf,anditsharmonics. 
 The specific numerical frequency  limits should be used whenever appropriate, but the letter designations of Table 1.1 may be  used whenever a short notation is desired.  1.5 RADAR DEVELOPMENT PRIOR TO WORLD WAR I1  Although the development of radar as a full-fledged technology did not occur until World War  11, the basic principle of radar detection is almost as old as the subject of electromagnetism  itself. Heinrich Hertz, in 1886, experimentally tested the theories of Maxwell and demonstrated  the similarity between radio and light waves. 
 The aerial and connector types were speci ﬁc Figure 2.3. Typical aerial polar diagrams for LRASV [ 7], (a) homing aerials; (b) broadside aerials.Table 2.3. Indicating units for ASV Mk. 
 Pulsed and pulsed doppler systems are common. Parabolic dish antennas, focal-point feeds, and low-noise solid-state re- ceivers are used. Magnetrons, phase-locked magnetrons, klystrons, traveling- wave tubes, and other forms of transmitters are used. 
 display saturating. If the radar was homing onto a target, the receiver gain would be steadily reduced to control the clutter levels. Figure 7.5shows idealised curves of the minimum detectable radar cross-section as a function of range for Pd=0.5 in different sea states with the radar at 1000 ft and 2000 ft for ASV Mk. 
 vol. 26. McGraw-Hill Book Company, New York, 1948. 
 The difference between the target position  arid tlic refercrice directioti is the arrgrtlar error. Tlie tracking radar attempts to position tlie  antenna to make the angular error zero. When the angular error is zero, the target is located  along the reference direction. 
 0EARSON  4HIS CRITERION MAXIMIZES THE PROBABILITY OF DETECTION  0$ FOR A GIVEN  PROBABILITY OF FALSE ALARM  0FA BY COMPARING THE LIKELIHOOD RATIO  , DEFINED BY %Q    TO AN APPROPRIATE THRESHOLD 4 THAT DETERMINES THE 0FA ! TARGET IS DECLARED PRESENT IF  ,X XPX X ( PX X (4NN N     \    \       q    WHERE PX x  XN\(  AND PX x  XN\(  ARE THE JOINT PROBABILITY DENSITY FUNCTIONS OF  THE N OBSERVATIONS  XI UNDER THE CONDITIONS OF TARGET PRESENCE AND TARGET ABSENCE  RESPEC 
 The improvement factor 'HITS PER BEAMWIDTH FIG. 15.12 Theoretical MTI improvement factor due to scan modulation; gaussian antenna pat- tern; n = number of pulses within the one-way half-power beamwidth.I SCAN IdB) I SCAN WB' . crv (METERS PER SECOND) FIG. 
 PARALLEL TERMS DISAPPEAR AND -ITZNERS DIFFRACTION COEFFICIENTS THEN REDUCE IDENTICALLY TO 5FIMTSEVS -ETHOD OF %QUIVALENT #URRENTS  5NDERTAKING WHAT HE CALLED A MORE RIGOROUS  EVALUATION OF THE FIELDS INDUCED ON A WEDGE  -ICHAELI DUPLICATED -ITZNERS RESULT FOR THE TOTAL SURFACE CURRENTS  CONFIRMING -ITZNERS PRIOR DEVELOPMENT  BUT HE DID NOT EXPLICITLY REMOVE THE 0/ SURFACE 
 Let the weights applied to the outputs  of the N taps be:  MTIANDPULSEDOPPLER RADARIII thatthesignalsareofthesameamplitude andwithaspacing suchthatwhenpulseatis subtracted frompulsea2,theresultiszero.However, aresidueisproduced whenpulsea3is subtracted frompulsea4,butnotwhenasissubtracted froma4,andsoon.Inthequadrature channel, thedoppler-frequency signalisshifted90°sothatthosepulsepairsthatwerelostin theIchannel arerecovered intheQdlatlllel, andviceversa.Thecombination oftheIandQ channels thusresultsinauniform signalwithnoloss.Thephaseofthepulsetrainrelativeto thatofthedoppler signalinFig.4.220andcisaspecialcasetoillustrate theeffect.Withother phaseandfrequency relationships, thereisstillalosswithasinglechannelMTIthatcanbe recovered bytheuseofboththeIandQchannels. Anextreme casewheretheblindphasewith onlyasinglechannel resultsinacomplete lossofsignaliswhenthedopplerfrequency ishalf theprfandthephaserelationship between thetwoissuchthattheechopulseslieonthezeros ofthedoppler-frequency sinewave.Thisisnotthecondition forablindspeedbutnevertheless thereisnosignal.However, ifthephaserelationship isshifted90°,asitisintheQchannel, thenalltheechopulsesoccuratthepeaksofthedoppler-frequency sinewave.Thus,toensure thesignalwillbeobtained without loss,bothIandQchannels aredesired. Digitalsignalprocessing hassomesignificant advantages overanalogdelaylines,parti­ cularlythosethatuseacoustic devices.Aswithmostdigitaltechnology, itispossibletoachieve greaterstability, repeatability, andprecision withdigitalprocessing thanwithanalogdelay­ linecancelers. 
 A cosecant-squared antenna pattern can also be produced by feeding the parabolic  reflector with two or more horns or with a linear array. If the horns are spaced and fed  properly, the combination of the secondary beams will give a smooth cosecant-squared pat­ tern over some range of angle. A reasonable approximation to the cosecant-squared pattern  can be obtained with but two horns. 
 The klystron amplifier may be pulsed by turning on and off the beam  accelerating voltage, similar to plate modulation of a triode or magnetron. The modulator in  this case must be capable of handling the full power of the beam. When the tube is modirlated  by pulsing the RF input signal, the beam current must be turned on and off; otherwise beam  power will be dissipated to no useful purpose in the collector in the interval between RF  pulses, and the efficiency of the tube will be low. 
 The steering commands  are simplified at the expense of M -I ad<liti.onal phase shifters and the added loss of a series  arrangement.  When separate power amplifiers are used at each element in a transmitting array or . 308 INTRODUCTION TO RADAR SYSTEMS  separate receivers are at each element in a receiving array, series-feed arrays are attractive  since their inherent loss is at low-power levels and is made up by the amplifiers. 
 2.78  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 two separate limiters described above, but the systems work because dynamic range is  sufficiently restricted by circuit components. Other systems, such as those that delib - erately hard-limit before pulse compression for CFAR reasons, do not have clutter  residue problems but suffer from significant target suppression in the clutter areas. An alternative to the use of limiters is the use of clutter maps in conjunction  with the CA-CFAR. 
 ONDS ON THE %ARTH OF MEAN RADIUS 2% SEEN FROM A RELATIVE ALTITUDE OF H KILOMETERS IS   RC H02 TA    WHERE @ 2   2%   H 2% IS A CONSEQUENCE OF THE SPHERICAL OBSERVATION GEOMETRY &OR  TYPICAL SATELLITE RADAR ALTIMETERS  THE PULSE 
 In general, the contributions to the total effective system noise temperature may he  divided into three categories: (1) the effective space noise temperature, (2) the effective noise-  temperature contributions due to RF lossy components, and (3) the effective noise tempera-  ture of the receiver itself.  Equation (12.16) applies to an ideal antenna with no sidelobes. In a practical antenna the  noise which appears at the antenna terminals enters via the sidelobe radiation as well as from  the main beam. 
 Radars with high resolution might  actually be capable of better performance than predicted on the basis of a Rayleigh clt~iter  model and a a' independent of radar resolution. A radar with a narrow pulse width or narrow  beamwidth not only sees less land clutter than a radar with larger pulse width or beam-  width, but it can see targets in those areas where clutter is less than the average, if these areas  can be resolved. In practice, there are regions of land where the clutter might be considerably  greater than the average and regions where it is considerably less than average. 
 - 4HE FOLLOWING SECTIONS DESCRIBE THE CHARACTERISTICS OF THE LINEAR AND NONLINEAR FRE 
 Hughes Aircraft Company: "K^-Band Integrated Radar and Communications Equip- ment for the Space Shuttle Orbiter Vehicle," preliminary design review, vol. 1, Mar. 14-24, 1978. 
 SEC. 913] THE AN/APQ-7 (EAGLE) SCANNER 291 operator can halb the nodding ofthe antenna, which then executes a conical scan topermit accurate homing. Asingle motor, rated at600 watts mechanical output, provides power forthe nod and spin motions. 
 ȱ Figure 5. ENVISAT-1 ASAR image of the Luson Strait acquired on 27 April 2005 at 01:53:42 UTC. Frame A (20 km ×20 km) highlights a shear-wave-generated eddy. 
 TRACK RESOLUTION ON THE ORDER OF   KILOMETERS  DETERMINED PRIMARILY BY SATELLITE VELOCITY !VERAGING IS hTHE NAME OF  THE GAMEv IN RADAR ALTIMETRY  &OR EXAMPLE  GLOBAL DATA SETS FROM INSTRUMENTS SUCH  AS 4/0%8 AND *ASON 
 SQUARED 
 10 100 1,000 Pulserepetition' frequency, Hz Figure1.1Plotofmaximum unambiguous rangeasafunction ofthepulserepetition frequency.. THE NATURE OF RADAR 3  range might result. Echoes that arrive after the transmission of the next pulse are called  secorrd-tinte-arotrrtd (or multiple-time-around) echoes. 
 J. F. Paris, “Probing thick vegetation canopies with a field microwave spectrometer,” IEEE Trans. 
 BAND MAGNETRON THAT DEVELOPS  7 OF AVERAGE 2& POWER AT  TYPICAL  DUTY CYCLE WOULD REQUIRE  TO  OF THE  
 Matc.:rials  such as polyethylene, polystyrene, Plexiglas, and Teflon are suitable for small microwave  lenses. They have low loss and may be easily shaped to the desired contour. Since the velocity  of propagation is greater in air than in the dielectric medium, a converging lens is thicker in the  middle than at the outer edges, just as in the optical case. 
 #ENTERED +ALMAN FILTER #ARTESIAN %ARTH 
 Defined in this manner, the monopulse sensitivity factor has the desir- able property of containing all target elevation angle-of-arrival information. The monopulse sensitivity factor for full-vector monopulse is I/I IS2I Ig7I K = - V^T <20-19)Uw0- /W2M where g^ = g^(6) = 2(B)/S0 = sum-beam voltage pattern normalized to unity gain ST = SrW = G7-(GVG7X) = transmit-beam voltage pattern normalized to unity gain For orthogonal aperture illumination functions, where 2J^=ivv2£Vv*A£ = O (usually the case in practice), this equation reduces to i/ngsiigriA. = —— (20.20) (1 + /2)1/2 This performance is presented graphically for several cases of interest in Fig. 
 ERROR CIRCUIT COMPARES THE CLUTTER RETURN FROM ONE SWEEP TO THE NEXT 4HROUGH A CLOSED LOOP  WHICH INCLUDES A SMOOTHING TIME CONSTANT  THE ERROR SIGNAL CONTROLS A PHASE SHIFTER AT THE COHO OUTPUT SUCH THAT THE DOPPLER SHIFT FROM PULSE TO PULSE IS REMOVED )T SHOULD BE NOTED THAT SINCE THE FIRST SWEEP ENTERING THE -4) IS TAKEN AS A REFERENCE  ANY PHASE SHIFT RUN 
 1, pp. 11–29, January 2003. 58. 
 72.Cheston. 1'.C:Microwave Lenses,Symposium 011Microwave Optics.McGillUniversity. Montreal. 
 Allen and B. L. Diamond, “Mutual coupling in array antennas,” MIT Lincoln Lab. 
 199–229. 80. J. 
 TRIP WAVEFORM 4HE PRECISION OF AN OCEAN 
 12.8 Geometry of complex fading calcu- lations. (From Ulaby, Moore, and Fung.21) LIMITS OFANTENNA BEAM ISODOPS LIMITS OFANTENNA BEAM frfmin dmox . quency is assumed to be the same for all maximum-range points and the same for all minimum-range points. 
 G1G^K2F2F2 -P, = (4^)3*4 W where Pr = received-signal power (at antenna terminals) Pt = transmitted-signal power (at antenna terminals) Gt = transmitting-antenna power gain Gr = receiving-antenna power gain a = radar target cross section X = wavelength Ff = pattern propagation factor for transmitting-antenna-to-target path Fr = pattern propagation factor for target-to-receiving-antenna path R - radar-to-target distance (range) This equation is not identical to Kerr's; he assumes that the same antenna is used for transmission and reception, so that GfGr becomes G2 and Ft2Fr2 be- comes F4. The only factors in the equation that require explanation are the pat- tern propagation factors F1 and F1.. The factor Ft is defined as the ratio, at the target position, of the field strength E to that which would exist at the same dis- tance from the radar in free space and in the antenna beam maximum-gain direc- tion, E0. 
 The averaged error signal controls a voltage-controlled coherent master oscillator (COMO), which determines the transmitted frequency of the radar. The COMO is slaved to the system reference oscillator frequency via the automatic frequency control (AFC) loop shown in Fig. 16.5. 
 NET WEIGHING  KG !T 3 BAND  ONE OF THEIR TUBES WITH  BEAMS HAD A PEAK POWER OF  K7   K7 AVERAGE POWER  OPERATED WITH  K6 ANODE VOLTAGE  HAD A  BANDWIDTH  AND A WEIGHT WITHOUT MAGNET OF  KG !N APPARENT EXTENSION OF THE MULTIPLE BEAM CONCEPT IS TO EMPLOY A SHEET ELECTRON  BEAM  WHICH IS AS THIN AND AS WIDE AND HAS AS MUCH CURRENT AS CAN BE ACHIEVED CON 
 (Recall from Sec. 10.2 that the output of the matched  filter is the autocorrelation of the input signal for which it is matched, if noise)can be neg-  lected.) The binary phase-coded sequence of 0, n values that result in equal sidelobes after  passage through the matched filter is called a Barker code. An example is shown in Fig. 
 The obje~tive of the usual adaptive antenna or the coherent sidelobe canceler is to adjust  the sidelobe levels to minimize the effects of noise or other unwanted signals. If the radar  application allows the use of antennas with extremely low sidelobes, the same result will be  achieved as with the adaptive antenna. In general, the extremely low sidelobe antenna can be a  better solution, if the desired low side lobe levels can be achieved and maintained economically. 
 M. Siegel, eds., Methods of Radar Cross Section Analysis , New York:  Academic Press, 1968, pp. 144–152. 
 37. Clark, W. I).: A High Power Phase Shifter for Phased-Array Systems. 
 However, if the target return momentarily faded or the  transponder signal was interrupted during flight so that track was lost, there was no  way to reinitialize new track data and subsequent location estimates became biased or  were lost. These systems were subsequently replaced with precision monostatic radars  and optical trackers. 23.7 TARGET CROSS SECTION14,15,30,66 –87 The bistatic radar cross section (RCS) of a target sB is a measure, as is the monostatic  radar cross section sM, of the energy scattered from the target in the direction of the  receiver. 
 With the initial estimation of the unknown parameters obtained by the genetic algorithm, the simplex method was used to determine the ﬁnal solutions. Compared with the real values detected from the simulated ﬁeld, the accuracy of the model and algorithm were evaluated. Figure 2shows the comparison between the estimated value of rheological parameters and the real values (the noise level here was 0.5 rad). 
 However, if two signals are present simultaneously, and if one  is much larger than the rms noise level at the limiter output, the weaker signal will be  suppressed by the stronger over the time interval that they overlap. The result is that the  probability of detecting the weaker signal is degraded.42 The hard limiting of superimposed  echoes in pulse-compression radar may also cause the generation of false targets in addition to  small-signal suppres~ion.~~  Pulse pmpression has also been used in conjunction with frequency-scan radar to  achieve improved range res~lution.~~ This was discussed briefly in Sec. 8.4. 
 (a) Regional scale in China; ( b) an ampliﬁed image of the area within the highway region of interest (outlined in the yellow rectangle); and ( c) location of the study area in China. According to the design criteria of the test highway, the permissible vertical post-construction settlement is 30 cm /y for regular road segments, 20 cm /y for culverts, and 10 cm /y for bridge connections. According to the statistics of the Fuoshan Transportation Bureau, the passenger ﬂow volume in 2014 of the Shunde District, where the highways are located, was up to 2018.31 million people per kilometer, whereas the freight ﬂow on the test highways was approximately 654.64 million tons per kilometer. 
 In several of the experiments referenced above, the dependence of sea backscatter  on angle relative to the wind direction was found by recording the radar return from a  spot on the surface while flying around it in a circle. Figure 15.10 a,b gives an example  of this behavior for grazing angles of about 45° and wind speeds close to 15 kt.31 The  figures contain results obtained independently by three different groups. The behavior  shown here is representative of that found generally: sea clutter is strongest viewed  upwind, weakest viewed crosswind, and of intermediate strength viewed downwind,  the total variation being about 5 dB. 
 15.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 has kept alive credibility in the Bragg scattering hypothesis in spite of the clear viola - tions of conditions and nonsequiturs noted above, as well as the lack of a proper theory  argued from first principles. The failure of this model to account for sea spikes and other non-Rayleigh returns  noted in Section 15.3 has led to an augmentation of the two-scale composite surface to  include breaking waves, a presumed source of these returns. One of the latest of these  two-scale-plus  models may be found in Kudryavtsev et al.,107,108 where breaking-   wave effects are incorporated analytically through the Phillips expression23 for the  density of breaking fronts as a function of wind speed (the parameter Λ(c) noted  in Section 15.2), with the scattering behavior based on Wetzel’s plume model (see  “Scattering by Surface Features”). 
 Arecent successful device forthe stabilization ofshipborne antennas includes computers and anassociated gyroscope, and islocated wi‘~inthe ship. The principal components ofthe stable vertical gyroscope area gimbal system sosupported that the outer and inner gimbal rings tilt respectively about the roll and pitch axes ofthe ship, asecond gimbal system supported byand within the first, and the gyroscope wheel sup- ported inthe second gimbal system. The wheel axis seeks the vertical because ofapendulous magnet carried byathird gimbal system, and compensation isprovided inthegyroscope fortheeffect ofship’s turns or changes ofspeed. 
 16.21] SPECIAL TESTEQUIPMENT 677 extra half-length line generates triggers atdouble the PRF. These are divided byacounting circuit before delivery tothe radar transmitter. 16.21. 
 March.1967. 47.Johnson. C.M.:FerritePhaseShifterfortheUHFRegion,IRETrans,vol.MTT-7. 
 E., J. L. Stone, J. 
 Serafin, “The microburst: hazard to aviation,” Weatherwise , vol. 37,   pp. 120–127, 1984. 
 MTI RADAR  2.416x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 in the velocity response curve. For many applications, a four-period stagger ratio is  best, and a good set of stagger ratios can be obtained by adding the first blind speed  (in V/VB) to the numbers −3, 2, −1, 3 (or 3, −2, 1, −3). Thus, in Figure 2.41‡, where  the first blind speed occurs at about V/VB = 14, the stagger ratio is 11:16:13:17§  (alternating the long and short periods keeps the transmitter duty cycle as nearly  constant as possible, as well as ensuring good response at the first null where   V = VB). 
 4.11 Multiple depressed collectors. (Courtesy of Hughes Aircraft Electron Dynamics Di- vision.} significant disadvantages. Often, several choices are feasible, and tradeoffs are then considered among system cost, schedule, and performance. 
        &)'52%   #ENTER 
 The efficiency is  about 25 percent. (Courtesy Varian Associ-  ates, Inc., Beverly, MA.)  RADAR TRANSMITTERS 195 Figure6.4Photograph oftheSFD-341 me­ chanically tunedC-bandcoaxialmagnetron forshipboard andground-based radars.This tubedelivers apeakpowerof250kWwitha 0.00Idutycycleoverthefrequency rangefrom 5.45to5.825GHz.Theefficiency is40to45 percent.(Courles)' Varia/lAssociates. l/lc., Bever/y.MA.) reliability thanconventional magnetrons. 
 This long propagation time, combined with the large number of beam  positions due to a narrow antenna beamwidth and a pulse doppler waveform with a  large number of pulses, results in unsatisfactory long search frame times when using  a single beam radar. If the active array radar is sized for long-range detection of ballistic missiles, the radar  will most likely have sufficient power to detect other targets. A cluster of multiple simul - taneous receive beams can be used to trade energy for a reduction in the volume search  frame time. 
 Hysell, “Nonlinear Rayleigh-Taylor instabilities, atmospheric  gravity waves, and equatorial spread F,” J. Geophys. Res ., vol. 
 Michaeli, “Elimination of infinites in equivalent edge currents, Part I: Fringe current compo - nents,” IEEE Trans ., vol. AP-34, pp. 912–918, July 1986. 
 The bandwidthof each individual filter must be wide enough to accept  the energy contained in the target echo signal. The width of the filter will depend upon the time  on target, equipment fluctuations~ and other effects which broaden the echo-signal spectrum as  discussed previously_. Each of the doppler filters can have its own individually set threshold  whose level is determined by the amount of noise or clutter within the filter. 
 The echo from a moving target produces a frequency shift due to the doppler effect, which  is a measure of the relative velocity. Relative velocity also can be determined from the rate of  change of range. Tracking radars often measure relative velocity in this manner rather than use  the doppler shift. 
 DOMAIN DIGITAL PULSE COMPRESSION PROCESSING !IR 3URVEILLANCE AND 0RECISION !PPROACH 2ADAR 3YSTEM  4HE !IR 3URVEILLANCE  AND 0RECISION !PPROACH 2ADAR 3YSTEM !30!2#3  IS INTENDED TO PROVIDE THE NEXT 
 89. pp. 10529–10546, 1984. 
 314 ANTENNAS, SCANNERS, ANDSTABILIZATION [SEC. 9.21 the other istransmitting apulse. Onaccount ofthe curvature ofthe earth and forreasons ofmicrowave propagation itisusually advantageous that thescanner beinstalled ashigh aspossible. 
 DOPPLER WAVE 
 15.7] AZIMUTH SCANRATE 599 torrecovery and toallow forirregular firing ofthe rotary spark-gap modulator, giving anaverage time interval of2500 psec between pulses, orav,of400. Thus, the value ofV,was setclose tothe permissible maximum foraradar setwith a200-mile range. For some applications, presentation ofgreater range would have been helpful. 
 At 10 MHz, the night and day levels are  the same; below 10 MHz, the noise decreases with decreasing frequency in daytime  and increases at night. Above 10 MHz, daytime levels are greater than those at night.  These effects can be partially explained by the very lossy long-range paths in day  that attenuate the long-range noise at the lower frequencies and by there being few  or no skywave paths to noise terrestrial sources at the higher frequencies at night. 
 The first three lines of Figure 25.14 illustrate this in  the frequency domain with line 3 showing the sampled IF signal. The bandpass  filter response on line 4 removes the unwanted spectral components to produce the  complex passband signal of line 5. This signal is then decimated by 2 and shifted  by –75 MHz to produce, at a 50 MHz sampling rate, the desired complex baseband  signal shown on line 9. 
 For this example, land clutter  returns are present at zero doppler with a normalized spectral spread of sfT = 0.01, and  chaff returns are present at a normalized doppler offset of fdT = 0.25 with a normalized  spectral spread of sfT = 0.05. The power ratio of the land clutter to that of the chaff is  denoted Q (dB). Thermal noise is not considered in this example. 
 Theionosphere isnotabenignpropagation medium. Astheamount ofionization changes, theoptimum frequency forpropagating energytoaparticular distance mustbe changed accordingly. Thelossesinpropagating through theionosphere changewithtime,and thetransmitter musthavesufficient excesspowertoovercome themaximum lossexpected. 
 ScanSAR requires rapid elevation beam steering, such  as through a phased array (e.g., TerraSAR-X), or selection of one among several range- offset feeds facing a reflector (e.g., HJ-1-C). In addition to suppressing scalloping,  good ScanSAR imagery requires that the several range sub-swaths be knitted together  such that the crossovers between antenna patterns are not evident. RADARSAT-1  was the first mission to implement (then to perfect) operational ScanSAR, which has  been adopted as a standard mode on many space-based SARs. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.56  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 A multiple simultaneous receive beam cluster can be formed in several different ways.  If analog beamforming is used, the receive signals can be split N ways into N separate  analog beamformers. 
 (2.57). The  capability of a surveillance radar is proportional to the prQduct .of its average power and  antenna aperture. Thus a small antenna requires a large transmitter power. 
     $ & !! "('  % #!  #(  # $  ## 
 BEAM PATTERNS FOR AN APERTURE   WAVELENGTHS LONG &IGURE  SHOWS THE RESIDUE FOR THE CASE WHEN THE FRACTION OF THE HORIZONTAL APERTURE WIDTH  A TRAVELED PER INTERPULSE PERIOD  4 P  6N   6X4PA  IS  EQUAL TO  AND WHEN THE NUMBER OF WAVELENGTHS THAT THE APERTURE TIP ROTATES PER INTERPULSE PERIOD   7 N   AVR4PK  IS EQUAL TO  4HE CORRESPONDING IMPROVEMENT  FACTOR IS  D" 4HE IMPROVEMENT FACTOR IS SHOWN IN &IGURE  FOR A RANGE OF NORMALIZED PLATFORM  MOTION 6N AS A FUNCTION OF NORMALIZED SCANNING DISPLACEMENTS  7N 4HE NONSCANNING  CASE IS SHOWN AS  7N    4HE IMPROVEMENT FACTORS WERE COMPUTED FOR THE  
 FIGURE 14.2  Radar cross section of a perfectly conducting sphere  normalized to the optics value pa2. The parameter ka = 2pa/l is the  circumference of the sphere expressed in wavelengths. ch14.indd   5 12/17/07   2:46:46 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
  TO SMOOTH 
 WAY ANTENNA PATTERNS ARE  SHOWN IN &IGURE  !S PREVIOUSLY MENTIONED  THE ABOVE TECHNIQUES 34#  TWO 
 Since the cross section of objects  within the Rayleigh region varies as l -4, rain and clouds are essentially invisible to radars  which operate at relatively long wavelengths (low frequencies). The usual radar targets are  much larger than raindrops or cloud particles, and lowering the radar frequency to the point  where rain or cloud echoes are negligibly small will not seriously reduce the cross section of  the larger desired targets. On the other hand, if it were desired to actually observe, rather than  eliminate, raindrop echoes, as in a meteorological or weather-observing radar, the higher  radar frequencies would be preferred. 
 119121Experiments at4.2GHzwitha55-ftrigidmetal space-frame radomeatasimulated rainrateof40mm/h(averyhighrate)hadameasured loss offrom1.0to1.7dB.!19Whentreatedtodecrease itswettability thelosswaslessthan0.3dB. Thetheoretical losscalculated bythemethoddescribed byB1eviswas3.4dB.Theexperimen-. tal values were less than predicted by theory since the water was not a uniform film, but  formed many small streaks that rapidly ran off the radome in narrow rivulets. 
 26Battan.L.J.:"RadarMeteorology." University ofChicago Press,Chicago, 1959. 27.Purves.C.G.:Geophysical AspectsorAtmospheric Refraction, NavalResearch Laboratory, Washing­ ton.D.C.Report7725.June7.1974. 2X.Kerr.D.E.(ed.):"Propagation ofShortRadioWaves," MITRadiation Laboratory Series,vol.U. 
 Such systems may use CW signals with or without doppler processing, but they may also use both pulse and FM techniques. Scatterometers capable of mea- suring response over a wide range of fre- quencies are called spectrometers.57 Vari- ous antenna patterns from pencil beams to fan beams may be used. CW and FM-CW Systems. 
 As shown inFig. 17.10b, the sweep components are produced by sawtooth generators using the signal volt- ages astheir source potentials sothat the ‘‘sawteeth” are modulated in the proper manner asthe scanner rotates (Sec. 13.16). 
 The change inthesize ofthetube with wavelength isthebasis ofthis rule. The pulse power input isoften limited bycathode emission and, since the cathode area isproportional tohz,pulse power input isalso proportional to~? Similar reasoning shows that ifthepulse power output islimited byr-fvoltage breakdown tvithin the tube, the same variation ofpower with wavelength istobe expect ed. This rule isanimportant one from thestandpoint ofsystem design. 
 When a tube presenting aparticular form ofdisplay istobeidentified, adescrip- tive adjective orcode designation isprefixed to“scope.” The word indicator isoften extended toinclude devices and circuits auxiliary to thecathode-ray tube. Both magnetic and electrostatic cathode-ray tubes are used (Sec. 13.1). 
 1976.  51. Bush. 
 55. Thimlar, M. E., et al.: Future Space-Based Computer Processors, Aerosp. 
 oneapproach istousethreeelevation beams.Thelowestbeamismadeasnarrowas practical inelevation. Itilluminates thelowangles.Nomonopulse anglemeasurement would beattempted withIhisbeam.TheotherIwobeamscoverthehigherangleswithrnonopulse processing. Sincethesefanheamsdonotilluminate thesurface theydonotsufferfrom multipath problems. 
 PROPLAB-PRO version 2.0, http://www.spacew.com/www/proplab.html. 55. B. 
 R.: Transversal Equalizers for Suppressing Distortion Echoes in Radar Sys- tems, Proc. Symp. Pulse Compression Techniques, pp. 
 ,Ê  1/9Ê, 
 31.Anonymous: Phased-Array PowerAmplifier. Microwave J.,vol.17,p.28,February, 1974. 32.Harper,' A.Y.:General Considerations intheSelection ofanAllSolidStateorPowerTubeApproach foraPhasedArrayRadarApplication, lEEConfPubl. 
 Finally, the complete doppler  filter bank is shown in Figure 2.61. This filter bank could be augmented with addi - tional filters around zero doppler, but these would not meet the design constraints  discussed above. The main benefit of a customized doppler filter bank design, as FIGURE  2.60 Third FIR filter in doppler filter bank design0.4 0.3 0.1 0 0.2 0.5 0.6 0.7 0.8 0.9 1−100−80−60−40−200 Relative Doppler – fdTMaximum Response – A (dB) Mismatch loss = 0.70612 dB FIGURE  2.61 Complete doppler filter bank design0.4 0.3 0.1 0 0.2 0.5 0.6 0.7 0.8 0.9 1−100−80−60−40−200 Relative Doppler – fdTMaximum Response – A (dB) ch02.indd   58 12/20/07   1:45:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
  
 It is desirable to center the clutter spectrum in the notch (i.e., minimum-response  region) of the AMTI filter in order to obtain maximum clutter rejection. This can be  accomplished by offsetting the IF or RF frequency of the radar signal by an amount  equal to the average doppler frequency of the clutter spectrum. Because the clutter  center frequency varies with range and azimuth when the radar is moving, it is neces - sary for the filter notch to track the doppler-offset frequency, using an open- or closed- loop control system such as TACCAR, described below. 
 POINTING DIRECTION #OURTESY OF (AZELTINE )NC . 
 Square-law detectors are preferred for some modern  floating-point processors. Postdetection integration (PDI) may be used where each  range-gate −doppler-filter output is linearly summed over several CPIs. For each range- doppler cell in the Σ channel, the PDI output is compared with a detection threshold  determined by a constant-false-alarm-rate (CFAR) process.23–26 Cells with amplitudes  greater than the CFAR threshold are labeled as detections. 
 TIONS RECEIVED VIA OBLIQUE SKYWAVE PROPAGATION MAY APPEAR AT RANGES IN EXCESS OF ^ KM 3UCH ECHOES MAY BE SPREAD IN DOPPLER AND CAN CONSTITUTE A SERIOUS PROB 
 (9) Then, the LS residual is calculated as ri,res=ri−Φisi,init. (10) In WASAR, the scattering of the targets is aspect dependent. However, the support sets of the subaperture images are highly overlapped, which means that a fairly accurate support Tcan be estimated from the data. 
 AVG    &OR EXAMPLE  IF  2    KM  4    +  &     ,OSS     6    MS  X    O  0AVG     7  '    D"  K    M 8 BAND   AND CR    M  THEN .%R       
  /" - 4HE )%%% 3TANDARD 2ADAR $EFINITIONS PROVIDE USEFUL DEFINITIONS FOR MANY OF THE  QUANTITIES NEEDED TO QUANTIFY -4) AND -4$ PERFORMANCE  BUT IN SOME CASES  THE VAGUENESS OF THE ORIGINAL DEFINITION AND THE LACK OF DISTINCTION BETWEEN PERFORMANCE AGAINST DISTRIBUTED CLUTTER VERSUS POINT CLUTTER RETURNS HAVE LED TO AMBIGUOUS INTERPRE 
 18. pp. 31-34, October. 
 (( E (J4     VV @ VV    4HUS  FOR SMALL VALUES OF  @  THE RESULTING MAGNITUDE AND PHASE RESPONSE IS THAT OF THE  ORIGINAL FILTER MODIFIED BY A SINUSOIDAL PHASE AND AMPLITUDE MODULATION AS GIVEN HERE   \   \ \   \ COS   `  (( 4 VV VA      `  
 Yaw stabilization isimplemented with the aidofahorizontal gyro- scope which iskept pointing north bymanual orautomatic reference to theearth’s magnetic field. Through amechanical orelectrical differen- tialthere isprovided attheindicator avoltage signifying thetrue bearing ofthe beam, that is,the difference between the relative bearing ofthe beam and the relative bearing ofthetrue north. Deck-tilt error isserious inairborne aswell asinshipborne radar. 
 2017 ,47, 884–897. [ CrossRef ] 16. Ghosh, A.; Mishra, N.; Ghosh, S. 
 J. A.: Elimination of Blind Velocitit";S of MTI Radar by Modulating the Interpulse Period,  IEEE Tra11s .. vol. 
 To minimize hardware, An1 should be small since a maximum of An1 - 1 range gates must be processed. 2. The probability of eclipse in at least one PRF is about 3/An1 for a three-PRF system, and so An1 should be at least eight or higher since range cannot be mea- sured if any PRF is eclipsed. 
 Active-switch pulse modulators can be ~-utio pi~lst~rs that  control the fiill power of the RF tube, mod-anode p~rlsers that are req~iired to switch at t hc ft~ll  bean] voltage of the RF ti~bc but with little current, or grlrl /~~il~c,r~ tllirt ol>ciatc at a Lr ~rilallc~  voltage than that of the RF beam.  The chief functional difference between a hard-tube modi~lator and a I~ne-typc modulator  is that the switching device in the hard-tube modulator controls both the beginning and the  end of the pulse. In the line-type modulator, the switch controls only the beg~nning of the  pulse. 
 The frequencies and 2500-|xs interpulse period are typical for a 200-mi L-band radar. The transmitter shown employs a magnetron. Because a magnetron is a pulsed oscillator that has no phase coherence between consecutive pulses, a phase ref- erence must be established for each transmitted pulse. 
 Luo, X.J.; Survey, C. Features of the shallow karst development and control of karst collapse in Wuhan. Carsologica Sin. 
 12, New York: McGraw-Hill Book Company, 1949. 11. Y . 
 In contrast to the array factor, this pattern has only one maximum  and is nonrepetitive. It is the well-known Fourier transform of a continuous constant- amplitude distribution. For uniform illumination, the beamwidth is  qBa a= = °0886 508 . 
 3  ESPECIALLY COUNTERMEA 
  
 COMPARATOR CIRCUITRY USED WITH A FOUR 
 This means  that very low sidelobe antennas are costly in terms of size and complexity when  compared with conventional antennas of similar gain and beamwidth characteristics.  Second, as the design sidelobes are pushed lower and lower, a point is reached where  ch24.indd   10 12/19/07   6:00:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 TO 
 III, Fig. 21.20, p. 1825. 
 The time-base trace  is arranged, by construction of the electrodes, to run  from the exact geometric centre of the tube to the outer  edge, and magnetic coils outside the tube itself (usually  placed quite close to a long neck) ‘pull’ the trace round  through the 360 degrees.  The coils produce magnetic deflection of the spot to  form the time-base trace, and if they are mounted on a  ring concentric with the axis of the tube, and are swung  round, then the light-line of the time-base will be drawn  round too. The coils in their mounting can be linked  directly, mechanically, with the rotating part of the  aerial system, but backlash may be experienced if the  distance between aerial and PPI tube is considerable. 
 The operator isespecially useful infollowing adesired target inthe presence ofother near-by signals, which may bedue toground objects, other aircraft, or“window” dropped tomake radar tracking difficult (Sec. 3.10). The proving-ground accuracy ofthis setisabout i25ydinrange at allranges, and about +1mill orbetter inangle. 
 The data, represented  by the solid line, are plotted on normal probability paper with Rayleigh and log-normal  distributions shown for comparison (dashed lines). The ordinate is the percent of time  for which the abscissa is exceeded , and the abscissa is the value of s  0 as defined by  Eq. 15.7, with A taken from Eq. 
 TIME PROCESSING )NSTEAD  SIMPLIFIED ALGORITHMS WITH IMPRESSIVE BUT  NONETHELESS SUBOPTI 
 When targets are widely spaced and in a clear environment, only one target detection  pair has a small D2, making these assignments obvious. Thus, the design of detection-to- track association is usually dominated by the more difficult conditions of closely spaced  targets or closely spaced targets and clutter. Figure 7.32 shows a common situation for  closely spaced targets and/or clutter. 
 In the past,  others, such as MADRE and some former Soviet Union skywave radars, employed  vertical two-dimensional arrays, up to 143 m high and 500 m wide in the case of the  Soviet radars. At low elevation angles, the antenna pattern is strongly influenced by the electri - cal and magnetic properties of the ground around and in front of the array. To achieve  ch20.indd   25 12/20/07   1:15:40 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 This ignores two factors: the cavity has only a finite linear range, and larger values of fm may produce sidebands that lie outside this range; for stability the servo that follows the cavity must have a response that rolls off at the higher frequencies. The simplest stabilization bridges result directly from the character of the transmission and reaction cavities. The transmission-cavity bridge might have the arrangement of Fig. 
 and M. R. Laing: Study of Doppler Spectra of Radar Sea Echo. 
 SET TO A FIXED hCOMPASSv BEARING AND A FIXED PERPENDICULAR DISTANCE FROM THE RADAR ORIGIN !T LEAST FOUR OF THESE HAVE TO BE PROVIDED 4HESE CAN BE INDIVIDU 
 14.1 Basic diagram of a CW radar. Noise in Sources. The primary noise problem is in the microwave source itself. 
 FILTER AREAS 2ADAR ALTITUDE      FT VELOCITY      KT TO RIGHT DIVE ANGLE     RADAR WAVELENGTH     CM 02&     K(Z RANGE GATE WIDTH     MS  RANGE GATE     DOPPLER FILTER AT  K(Z BANDWIDTH     K(Z BEAMWIDTH     CIRCULAR  MAIN 
 Thekeep-alive canbereplaced asasupplier ofpriming electrons intheTRbyaradio­ activesource,suchastritium, whichproduces low-energy-Ievel betarays.S2Thetritiumis incompound formasatritidefilm.Thereplacement ofthekeep-alive byradioactive tritium eliminates theexcessnoiseofthekeep-alive andincreases thelifeoftheTRbyan'orderof magnitude. SinceatritiumTRneedsnoactivevoltages, amechanical shutterisnotrequired to protectthereceiverfromnearbytransmissions whentheradaristurnedoff.Thisalsoimproves thereliability. Thetritium-activated TRisusuallyfollowed byadiodelimiter.Thecombina­ tionofthetwoiscalledapassiveTR-Iimiter andiswidelyusedasareceiver protector. 
 Bothofthesewaveforms have their areas ofapplication; butinthepast,thelinearFM,orchirp,pulsecompression has probably beenmorewidelyused.Thetimesidelobesofthephase-coded pulseareoftheorder of1/BT.Thepeaksidelobeofthechirpwaveform isgenerally higher,butataslightsacrifice in signal-to-noise ratioitcanbemadelowbymeansofweighting networks. Thechirpwaveform isdoppler-tolerant inthatasinglepulse-compression filtercanbeused,butitcannotprovide anindependent rangeanddoppler measurement. Withmovingtargets,thephase-coded pulse mightrequireabankofcontiguous matched filterscovering theexpected rangeofdoppler frequencies. 
 Another technique for reducing the effect of the  reflected radiation intercepted by the feed is to raise a portion of the reflecting surface at the  center (apex) of the paraboloid. The raised surface is made of such a size and distance from  the original reflector contour as to produce at the focus a reflected signal equal in amplitude  but opposite in phase to the signal reflected from the remainder of the reflector. The two  reflected signals cancel at the feed, so that there is no mismatch. 
 TRACK MAY NOT BE IMAGED AT ALL )NCREASING AZIMUTH RESOLUTION BY BROADENING THE ANTENNA PATTERN  EITHER BY REDUCING THE APERTURE LENGTH OR SPOILING THE BEAM  HAS THE DISADVANTAGE OF REDUCING THE ANTENNAS GAIN  WHICH USUALLY IS NOT DESIRABLE FOR SPACE 
 Alternate approaches to providing this frequency offset can be implemented with  digital exciters or on receive. For some applications, it may be necessary to use multiple  control loops, each one covering a specific range interval, or to vary the offset fre - quency in range. This is possible if the frequency offset is implemented on receive (but  not on transmit). 
 WAVE TUBE MEANS THAT IT CAN HANDLE LARGER  POWER AT THE HIGHER FREQUENCIES 4HE GYROTRON HAS MAINLY BEEN OF SIGNIFICANCE FOR HIGH 
 2EPEAT /RBIT  4HE PRECEDENT FOR THIS IS 'EOSAT  ITS FIRST  MONTHS WERE  DEVOTED TO GEODESY FOR WHICH A NON 
 Simkins, V . C. Vannicola, and J. 
 This isnot true, fortunately, ashas been vividly demonstrated bythe development ofmethods, described inChap. 16,which make possible a distinction between moving targets and their surroundings. Insome cases theechoes from thelatter areautomatically rejected. 
 TIONARY AND MOVING GROUND TARGETS SEE &IGURE   4HE PHASED ARRAY ANTENNA FOR THIS SYSTEM IS A  
 These  slopes are derived from the SSH measurements summarized above, but this applica - tion has its own unique implications for system design. The highlights are reviewed  in the following paragraphs. Sea-surface slope87 is derived by taking the difference between two neighboring  height measurements, where the slope tangent equals “rise over run.” The key word  for these measurements is precision : the standard deviation (noise) of the sea-surface  height measurement about its mean value. 
 105. S. M. 
 REFERENCES  1. J. R. 
 and J. Mattern: Reccivers. chap. 
  
 Wilson80 © IEEE 1987 ) ch07.indd   53 12/17/07   2:15:08 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 RESOLUTION STRIP 
 4- . w ioo in mi By substituting values for the derivatives, a time plot of tracking lag may be de- termined as shown in Fig. 18.23. 
 DOMAIN RADAR  AND ITS ABILITY TO INTEGRATE THE RECEIVED SIGNAL LEVEL IMPROVES THE SYSTEM SENSITIVITY 4HE CALIBRATION OF THE RADAR DOES  OF COURSE  DEPEND ON STABLE SYSTEM CHARACTERISTICS AND ANTENNA PARAMETERS THAT ARE INVARIANT WITH THE SPACING OF THE FRONT SURFACE AND THE ANTENNA !LTHOUGH ON FIRST CONSIDERATION  FREQUENCY DOMAIN RADARS SHOULD OFFER A SUPERIOR SENSITIVITY TO TIME 
 3.3.4.1 PPI display The PPI display showed slant range from zero out to 10, 30 or 50 miles, with a further display option for 50 –100 miles. The cathode ray tube (CRT) used a long persistence phosphor with a persistence (afterglow) of 1 –2 s. This allowed successive returns in a beam dwell to be integrated and to maintain a paint from one scan to the next. 
 Appl. Meteorol .,   vol. 9, pp. 
 OUT WILL EXCEED THE SPEED OF RESPONSE  OF THE CLOSED LOOP  AND THE -4) MUST BE RESET 4HIS TYPE OF CLOSED 
 4.3.4 Leigh Light indicator and pilot ’s indicator When locked onto a target, the bearing of the target relative to the line of ﬂight (up to ±30 °) and the target range were fed to an azimuth meter in the pilot ’s indicator, seeﬁgure 4.13. This indicator had a small lamp that was illuminated when the strobe was ‘locked on ’. A further signal was provided to the Leigh Light indicator ﬁgure 4.14. 
 The most successful oxide-cathode high-power switch tube isthe 715B developed atBell Telephone Laboratories. The 715B has agold-clad grid which poisons and “absorbs” activematerial, thereby lowering its efficiency asathermionic emitter. TABLE 1O.4.—TYE’ICAL OIV:RATING cmm~c’rmus’mcs Tube type 3D21 3E2!l 715B 5D21 304TH 6C21 6D21 527Cath- ode type Oxide Oxide Oxide Oxide Th-W Th-W Th-W Th-VVC’ath- ode >owei-, watts 10 14 56 56 125 140 150 770Max. 
 MTI RADAR  2.776x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 is shown in Figure 2.81. (Transmitter noise will be used in the following discussion  to represent all possible system instabilities that create noise-like pulse-compression  time sidelobes.) Limiter 1 is set to limit the system dynamic range to the range between peak clutter  and clutter instability noise. Limiter 2 is set so that the dynamic range at its output is  equal to the expected MTI improvement factor as limited by clutter spectral spread  or low-frequency transmitter power supply ripple. 
 PULSE WIDTH IS DETERMINED BY THE TOTAL BANDWIDTH OF ALL THE PULSES  AND THE DOPPLER RESOLUTION IS DETERMINED BY THE RECIPROCAL OF THE WAVEFORM DURATION  4 &OR EXAMPLE  A TYPICAL WAVEFORM IN THIS CLASS  HAS . CONTIGUOUS PULSES OF WIDTH  T WHOSE SPECTRA OF WIDTH  S  ARE PLACED SIDE BY SIDE  IN FREQUENCY TO ELIMINATE GAPS IN THE COMPOSITE SPECTRUM 3INCE THE WAVEFORM BAND 
 DELAYED VERSION OF THE TRANSMITTED WAVEFORM  4HE OUTPUT RESULTS IN AN OUTPUT IN WHICH THE AMPLITUDE OF THE LATTER AND ITS POSITION IN  DELAY TIME IS RELATED TO THE TARGET RADAR CHARACTERISTIC 4HIS TYPE OF RECEIVER IS WIDELY USED TO PROCESS CHIRP  STEP FREQUENCY  AND PSEUDO 
 Their properties differ significantly from  microwave tubes and require major changes in system design pl~ilosopliy wlien they are used.  .  6.2 THE MAGNETRON OSCILLATOR  More than any other single device, the high-power magnetron oscillator invented in  19392 made possible the successful development of microwave radar during World War 11. 
 . 
 PLANE RANGE RESOLU 
 Smith, “Adaptive Radar,” in Wiley Encyclopedia of Electrical and Electronic Engineering ,  J. G. Webster (ed.), vol. 
 The signals are integrated in opposite polarity oncondenser Clbymeans ofthe diodes. Anegative signal from Vjdrives anegative charge through V3.toCl. Asignal from V,drives anegative charge toground through VWThe potential onC, isthe output signal. 
 The Rayleigh is actually a member of the Weibull family, and results when  ex= 2. The exponential pdf is also a member of the Weibull family when ex= 1. (Further  discussion of the Weibull pdf is given in Sec. 
 Thefactor 111inthis equation cantakeonanyintegervalue.Asthefrequency ischanged. onebeamafteranother willappearanddisappear. eachbeamcorresponding toadifferent valueofm.Onlyonebeam atatimewillberadiated ifthegratingloberelation ofEq.(8.21)issatisfied; else-multiple beams,orgratinglobes,willappear.Itcanbeshownthatifanarrayradiates ataparticular anglecorresponding toavalueminEq.(8.17b)whenthefrequency isf,thenforsomeother value 111(abeamwil.1beradiated atthesameanglewhenthefrequency isI!=(ml/m)! Consider. 
 The principal problem with this approach is deciding where in the spectrum lies the boundary between the larger components that do the tilting and smaller components that are Bragg- . resonant. Many papers have been written to describe the evolution of this theory; for a complete summary, the reader is referred to Fung's development in Ref. 
 In this paper, we aim to improve the most commonly used model, the α-Chapman model, with a constant scale height HT[7]: Ne=NmF2×e1−z−e−z 2 z=h−hmF2 HT, (3) where NmF2represents the electron density at the peak height hmF2of the F2layer. Both NmF2and hmF2can be directly obtained from the ionosonde station. Therefore, HTis the only parameter that we need to estimate to determine a topside proﬁle. 
 pp. 6n 6J9. Dec .. 
 Geosci. Remote Sens. 2016 ,54, 4712–4731. 
 A. I., and V. V. 
 The low insertion loss of a CFA also allows power reflected at the output to be passed back through the tube to its input; in many cases the reflected output power coming back out of the input may even exceed the incoming drive power. A properly rated isolator3'25 is thus a necessity between stages of a CFA chain. Certain additional problems long identified with magnetron operation are also common to operation of CFAs. 
 60, pp. 743-744, June, 1972. THE RADAR EQUATION 67  56. 
 This is in contrast to shot noise  or thermal noise, which is independent of frequency. Thus, at the lower range of frequencies  (audio or video region), where the doppler frequencies usually are found, the detector of the  CW receiver can introduce a considerable amount of flicker noise, resulting in reduced receiver  sensitivity. For short-range, low-power, applications this decrease in sensitivity might be  tolerated since it can be cornpensat& by a modest increase in antenna aperture and/or  additional transmitter power. 
 BOARD AVIATION WEATHER RADARS TO NOT DETECT INTENSE CONVECTIVE CELLS BEHIND CLOSER  HIGH ATTENUATION THUNDERSTORMS  3EVERE STORMS WITH HIGH PRECIPITATION RATES ALSO CAUSE HIGH  ATTENUATION EVEN AT  
 Onthesearch antennas, agiven target shows either ontheleftantenna oronthe right, depending onitslocation with respect tothe aircraft, never onboth. Onthehoming antennas, however, because oftheover- lapping coverage ofthetwo beams, atarget will show asignal atthesame range both totheleft and totheright ofthecenter line. Acomparison ofthe strength ofthe two returns shows the radar observer inwhich direction course must bealtered tohome onthe target. 
 ££°Ó{  2!$!2 (!.$"//+  ££°xÊ 
 124 LIMITATIONS OF PULSE RADAR [SEC. 4.4 l/v, long, which previously separated successive pulses. Atthe same time the average power iskept constant byareduction inpulse power bythe factor rv,. 
 , Ê 1    0HASED ARRAY ANTENNAS CAN BE DESIGNED TO HAVE DETERMINISTIC ANTENNA PATTERNS OR ADAP 
    . Ó°xä  2!$!2 (!.$"//+  &IGURE  SHOWS THE EFFECT OF THE RETURNED SIGNAL IF THE POINT CLUTTER EXCEEDS THE  )& LIMIT LEVEL BY  D" 7HEN THE SIGNAL REACHES THE LIMIT LEVEL  THERE IS A STEP INCREASE  OF RESIDUE OF ABOUT  D" 4$72 USES CLUTTER MAPS TO NORMALIZE THE RESIDUE FROM THE STRONG POINTS OF CLUTTER THAT EXCEED THE LIMIT LEVEL  4HE WEATHER MODE OF !IRPORT 3URVEILLANCE 2ADARS IS DEMONSTRATED BY FIVE 
 DELAY CANCELLATION IS USED 4HIS IS BECAUSE THE SINGLE 
 It was one of the first practical exatnples of electronic scanning  and has been widely employed. It is discussed separately in the next section. One of ttte nlore  popular forms of phase shifters is one that varies the physical length of line to obtain a change  in phase, especially when the lengths of line are quantized digitally. 
 Appl. Meteorol. , vol. 
 ASTIA AD617693. 16. Coquin, G. 
 CEPT NOISE JAMMERS (/* IS A MEANS WHEREBY A MISSILE GUIDANCE RECEIVER UTILIZES THE SELF 
 6.3. Azimuth Compression of the Range Compressed ISAR Signal and Complex Imaging Pulsar ISAR signals reemitted by the asteroid are registered in a far ﬁeld zone of electromagnetic waves propagation. It means that a plane wave approximation can be applied and, hence, an inverse Fourier transform can be used in order to perform azimuth compression of the range compressed ISAR signal, i.e., ˆS(k,ˆp)=1 NN−1⎭summationdisplay p=0ˆS(k,p)·exp⎭parenleftBigg j2π·p·ˆp N⎭parenrightBigg , (11) where ˆp=0,N−1is the discrete coordinate of the asteroid’s generic point at the moment of imaging. 
 LENGTH APERTURE PATTERNS SHOWN IN &IGURE  !NDREWS HAS DEVELOPED AN OPTIMIZATION PROCEDURE FOR PLATFORM 
 [ CrossRef ] 30. Aimaiti, Y.; Yamazaki, F.; Liu, W. Multi-sensor insar analysis of progressive land subsidence over the coastal city of Urayasu, Japan. 
 R.: Low Conversion Loss X Band Mixer, Microwave J., vol. 21, pp. 53-59, April, 1978  57. 
 BEAM  JAMMER CANCELLATION  TARGET $O! ESTIMATION IN PRESENCE OF JAMMER  TWO 
 ItisalsoneededinADT,or track-while-scan systems, topreventthetracking computer frombeingoverloaded byextra­ neouscluttertargetsornoise.CFAR,however, isnotwithout itsdisadvantages andcanbe considered anecessary evil.Itintroduces anadditional losscompared tooptimum detection, andinsomesystems thenumber ofpulsesprocessed needstobelargetokeepthelosslow. Moreimportant. CFARmaintains thefalse-alarm rateconstant attheexpenseoftheprobabil­ ityofdetection. 
 S. Reed: Adaptive Arrays in Airborne MTI Radar. IEEE Truns.. 
 The IF  output of the correlation mixer is evaluated using the identity  2cos x cos y = cos( x + y) + cos ( x − y)  where the first term on the right-hand side of the equation corresponds to the upper  sideband and the second to the lower sideband at the mixer output. The upper sideband  is rejected by the bandpass filter to yield  x t At Tt TR RIF rect rect ( ) cos[=−  −   ⋅τ τ 2 2 2 2 π τ π τ πα τ τ τ π α α f t f t td R R IF( ) ( ) ( ) ( ) ( − + − + − − + −R Rt)( ) ]− +τ φ2   (8.27) where fIF = f0 − fR is the IF carrier frequency ( f0 > fR is assumed) and the carrier phase  shift is   φ π τ τ πα τ τ = − − − − 2 22fR R R R ( ) ( )   The IF signal is an LFM waveform with reduced slope a −aR (the factor that multi - plies the quadratic term in the argument of the cosine) and a frequency offset relative  to the IF carrier frequency fIF given by   δ α τ τ f fd R R = + −( )  (8.28) The duration of the reference waveform is required to exceed the transmit pulse - width to avoid a loss in SNR caused by target echoes that are not contained within the  reference waveform.  Equal Transmit and Reference Waveform LFM Slopes. 
 Skolnik (cd.), Mc(iraw-Hill llook Company. New York. 1970. 
 PROFILER TECHNOLOGY AND TO THE SEQUENCE OF 4ROPOSPHERIC 0ROFILING 3YMPOSIA FOR TROPOSPHERIC PROFILING APPLICATIONS OF WINDS AND OTHER METE 
 PULSE JITTER  WHICH IS ONE OF THE MOST EFFECTIVE TECHNIQUES AGAINST DECEPTION JAMMERS THAT RELY ON ANTICIPATING THE RADAR TRANSMITTER PULSE #OHERENT DOPPLER PROCESSORS ARE ALSO GENERALLY VULNERABLE TO IMPULSIVE RADIO FREQUENCY INTERFER 
 Ablockdiagram oftheFM-CW radarwithasideband superheterodyne receiver isshowninFig.3.13.Aportionofthefrequency-modulated transmitted signalisappliedtoa mixeralongwiththeoscillator signal.Theselection ofthelocal-oscillator frequencyisabit different fromthatintheusualsuperheterodyne receiver. Thelocal-oscillator frequency.!iF shouldbethesameastheintermediate frequency usedinthereceiver, whereas intheconven­ tionalsuperheterodyne theLOfrequency isofthesameorderofmagnitude astheRFsignal. Theoutputofthemixerconsists ofthevaryingtransmitter frequency lo{t)plustwosideband frequencies, oneoneithersideof/o(t)andseparated from/o{t) bythelocal-oscillator frequency. 
 SEC. 10.11] MISCELLANEOUS COMPONENTS 385 the input and output ends ofFig. 10”45b should beavoided. 
 The most usual type ofcoding consists ofagroup ofpulses succeeding each other byprecise, unequal time intervals. The responsive circuit at the receiver isarranged torecognize only agroup with precisely these spacings. .4similar combination isextremely unlikely tooccur inthe interference. 
 l Cutler. C. C.. 
 Above: Horizontal characteristic.  Bel ow: Section through the 2x2  directivity patterns.   The antenna features four feeder antennas, e.g. 
       
 Friedle: Forward Scatter of Electromagnetic Waves  by Spheres, IRE WESCON Con[). Record. vol. 
 RESOLUTION EQUIVALENT TO AN UNCODED  
 FIELDS ON  EACH ANTENNA (OWEVER  A SUM 
 BASED .,&- DISCUSSED EARLIER 4HIS PARTICULAR CODE IS  CALLED 0HASE FROM .ONLINEAR &REQUENCY 0.,  AND ITS AUTOCORRELATION FUNCTION IS  SHOWN IN &IGURE  FOR A  
 J., and A. J. Poggio: Numerical Electromagnetic Code (NEC)—Method of Moments, NOSC Tech. 
 The following section shows how the two quite differently structured CFAR algorithms: the  CAGO-  CFAR with its low processing requirements but often ineffective threshol ding and the  OS-CFAR with its effective t hresholding, but heavy processing requir ements for sorting, can  be freely combined.   12.1.4  CAOS -CFAR   The CAGO- CFAR (or the CA -CFAR) can be freely combined with the OS- CFAR. The new  circuit is then termed CAOS OFAR ( Cell Averaging Ordered S tatistic). 
 critical or plasma frequency are sometimes used almost interchangeably; when this occurs, the relation implied is Ne = /2/81, where Ne is free-electron density, in numbers per cubic meter, and/is the frequency, in hertz. For the little tables shown in Figs. 24.9 and 24.10, FC is the critical frequency, in megahertz; HC is the height of maximum ionization or the nose of the parabola, in kilometers; and YM is the semithickness of the parabola, in kilometers. 
 With the advent of newer, high-resolution sondes that may be  lowered to the surface from a ship, the impression is given that the evaporation duct may  be measured directly. For practical applications, however, this impression is false and a  direct measurement should not be attempted. Due to the turbulent nature of the tropo - sphere at the ocean surface, a refractivity profile measured at one time would most likely  not be the same as one measured at another time, even when the two measurements are  seconds apart. 
  M PER FT OF  EXPOSED COLUMN AT  '(Z 3TRING SUSPENSION METHODS ARE BEST  IMPLEMENTED INDOORS  WHERE A N OVERHEAD SUP 
 For a typical backward-wave CFA, the power output can vary 100 percent for a 10  percent change in frequency." It is possible, however, with conventional modulator  techniques, to operate the backward-wave CFA over a wide band with little change in output  power. The type of modulators normally used with cathode-pulsed CFAs can readily compen-  sate for the power variation with frequency of a backward-wave CFA and hold the variation of  output power within acceptable levels. This is a result of the nature of the dispersion character-  istics of such tubes. 
 NELS  THUS NEGATING THE TAPERING EFFECT  4HE TRANSFORMATION  4 THAT ENCODES THE SUB 
 TO 
 For designs employing an amplifier for each  ch20.indd   23 12/20/07   1:15:39 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 
 E.: Multipath Phase Errors in CW-FM Tracking Systems, IRE Trans., vol. AP-3.  pp. 
 However, at short range or with rela­ tively large targets (as might be seen by a radar seeker on a homing missile), angular lluct ua­ tions may be the chief factor limiting tracking accuracy. Angle fluctuations affect all tracking  radars whether conical-scan, sequential-lobing, or monopulse.  Consider a rather simplified model of a complex radar target consisting of two indepen­ dent isotropic scatterers separated by an angular distance Ou, as measured from the radar. 
 In normal radar operation, the surface refractivity is measured periodically at the radar site, where it is used in conjunction with measured target elevation QT and range RT to perform online table lookup of the tabulated height-refractivity parameters. The final height is computed by means of the interpolation dhT dhT Bh7 hT= hT (Rk9Qk9Nk) + — (RT - R,) + — (Or-9,) + -(N-AT*) (20.9)dRk aeA. BNk where Rk,$k, and Nk are the closest stored values of range, elevation angle, and surface refractivity to the measured values. 
 Figure 2.53 a shows the filter designed to respond to targets in the middle of the  doppler passband. The sidelobes near zero velocity are 66 dB down from the peak,  thus providing good clutter rejection for clutter within 5% of zero doppler. The −46 dB  sidelobe provides chaff rejection to ±16%. 
 FED OPTICAL  "EAMWIDTH  ¾ BEAMWIDTH   !FTER &RANK ./4% !LL BEAMWIDTHS ARE IN DEGREES AND REFER TO THE BROADSIDE BEAMWIDTH  KG   GUIDE WAVELENGTH AND  K   FREE 
 INDEX  A posteriori probability, 377-378  A priori probability, 378  A sandwich radome, 267  A-scope, 6, 354  Absorbers, and radar cross section, 553  Accuracy, FM-CW altimeter, 86-87  Accuracy, radar measurement, 400-41 1  Acoustic delay lines, MTI, 126  Acquisition radar, 153  Acquisition, in tracking radar, 177-178  Active-switch modulator, 215  A/D converter, in MTI, 120  Adaptive antennas, 332-333  Adaptive array, in MTI, 145  ~da~tive'~~~, 142  Adaptive tracking, 180, 185  Adaptive threshold, in MTD, 128  Adaptive video threshold (AVT), 392, 488  ADT, 153, 183-186, 392  Air-supported radomes, 265  Air-surveillance radar, 536-541  Air traffic control radar, 536-541  HF OTH, 533  Aircraft, radar cross sections of, 39-44  Aircralt radornes, 267-268  Alpha-beta (a$) tracker, 184-185  Altimeter, FM-CW, 84-87  Altimeter, and snow, 482  Altitude return, in pulse doppler radar, 145  Ambiguity diagram, 41 1-420  Amplitron. 209. 212 Amplitude-comparison monopulse, 160-165  Amplitude fluctuations, in tracking radar,  167- 168  AMTI, 140-147  and SAR, 528  AN/FPS-85, 213  computer control of, 324, 328  AN/SPS-48, 301-302  AN/SPY-1, 309  AN/TPN- 19, 259-260  AN/TPS-59, 219  Angel echoes, 508-512  Angle fluctuations, 168-169  Angular accuracy, 409-41 1  of tracking radar, 167-172 -  Anomalous propagation, 450-456  Antenna scanning modulation, in MTI,  134-136, 144  Antenna temperature, 461, 464  Antennas, 223-337  adaptive, 332-333  aperture blocking in, 223-224, 239, 241, 266  aperture efficiency of, 288, 232  artificial dielectric lens, 249-252  Bayliss pattern for, 258  beam shape loss of, 58-59  az-el mount for, 271  Bootlace, 3 16  Butler beam-forming, 31 1-314  Cassegrain, 73, 240-242  constrained lens, 251  Aposteriori probability, 377-378 Aprioriprobability, 378 Asandwich radome, 267 A-scope, 6,354 Absorbers, andradarcrosssection,553 Accuracy, FM-CW altimeter, 86-87 Accuracy, radarmeasurement, 400-411 Acoustic delaylines,MTI,126 Acquisition radar,153 Acquisition, intracking radar,177-178 Active-switch modulator, 215 AIDconverter, inMTI,120 Adaptive antennas, 332-333 Adaprivearray, inMTI,145 Adaptive'MTl, 142 Adaptive tracking, 180,185 Adaptive threshold, inMTD,128 Adaptive videothreshold (AVT),392,488 ADT,153,183-186,392 Air-supported radomes, 265 Air-surveillance radar,536-541 Airtrafficcontrolradar,536-541 HFOTH,533 Aircrafi, radarcrosssections of,39-44 Aircraftradomes, 267-268 Alpha-beta (cx-P)tracker,184-185 Altimeter, FM-CW, 84-87 Altimeter, andsnow,482 Altitude return,inpulsedoppler radar,145 Ambiguity diagram, 411-420 Amplitron, 209.212INDEX Amplitude-comparison monopulse, 160-165 Amplitude fluctuations, intracking radar, 167-168 AMTI,140-147 andSAR,528 AN/FPS-85, 213 computer controlof,324,328 AN/SPS-48, 301-302 AN/SPY-l,309 AN(fPN-19,259-260 AN(fPS-59,219 Angelechoes,508-512 Anglefluctuations, 168-169 Angular accuracy, 409-411 oftracking radar,167-172 Anomalous propagation, 450-456 Antenna scanning modulation, inMTI, 134-136, 144 Antenna temperature, 461,464 Antennas, 223-337 adaptive, 332-333 aperture blocking in,223-224, 239, 241, 266 aperture efficiency of,288,232 artificial dielectric lens,249-252 Baylisspatternfor,258 beamshapelossof,58-59 az-elmountfor,271 Bootlace, 316 Butlerbeam-forming, 311-314 Cassegrain, 73,240-242 constrained lens,251. 
 The other is the power amplifier, which utilizes a low power,  stable oscillator whose output is raised to the required power level by one or more amplifie;  stages. The ~lystron, traveling-wave tube, and the crossed-field amplifier are examples of  microwave power-amplifier tubes. The choice between the power oscillator and the power  amplifier is governed mainly by the particular radar application. 
 TIES  IE  IT CAN HANDLE A DIVERSITY OF REFLECTORSCATTERER SHAPES AND COMBINATIONS AND ALSO HAS VARIOUS FEED MODELS TO DRAW UPON )T ALSO HAS FEED AND ARRAY WIZARDS THAT EMPLOY FULL 
 Kirchner, R. L. Huff, D. 
 So the theoretic ally  maximum range of given radar set can be calculated.     Transmitters Power   The more transmitted power, the more power of range, but: Note this fourth root!   To double the maximum range you must increase the transmitted power 16 -fold!   The inversion of this a rgument is also permissible: if the transmit power is reduced by 1/16 (e.g.  failures into two of 32 transmitter modules), then the change on the maximum range of the radar set  is negligible in the practice:  4 415 16 0.9375 0.982 2%   . 
 N. Bracewell:" Radio Astronomy," Oxford University Press, London, 1955.  57. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.102  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 37. T. 
 DISTRIBUTED !N EXAMPLE OF THE MEASURED  DISTRIBUTION OF THE APPARENT TARGET ANGLE OF A SMALL TWO 
 F 4HE RESULTANT ANTENNA  BEAM PATTERN POINTS IN THE POSITIVE  Z 
 There are two different types of civilran air-surve~llanc~  radars used by the Federal Aviation Administration for the control of air traffic in t11c Ij~lited  States. One is the S-band 60 nmi airport-si~rveillu~~ce radar (ASH), t:ig. 14 9, wll~cll l,~c~v~clcb  information on aircraft in the vicinity of airports. 
 18.3  18.3 Monopulse (Simultane ous Lobing)  .........................  18.8  Amplitude-Comparison  Monopulse  .....................  18.9 . 
 This relationship is written as * The terms synthetic antenna and synthetic aperture are used interchangeably in this chapter. Peff = 5T- (2L2)^Leff Here peff is the effective half-power beamwidth of the synthetic aperture, and Leff is the length of the synthetic aperture. A more detailed derivation of the resolution capability of a synthetic aperture radar will be given later in this chapter. 
 More detailed  information will be found in some of the subsequent chapters or in the references listed at the  end of the chapter.  2.2 MINIMUM DETECTABLE SIGNAL  ' ..  The ability of a radar receiver to detect a weak echo signal is limited by the noise energy that  occupies the same portion of the frequency spectrum as does· the signal energy. 
 Range-measuring Doppler System.—In order tomeasure the range ofone ormore targets, the outgoing wave must bemarked, or modulated, insome way and the time required forthe marks onthe wave train toreturn must bemeasured. The modulation may beof either the amplitude orthe frequency type, the techniques forthe two methods being quite different. The most familiar method for measurement involving amplitude modulation istoemit apulse ofwaves and determine thetime delay in v “fTotransmithng= reflector -\Audloamplfierand ~ytranslator chassis Pluginfalters Toreceiwng reflector 1~1~. 
 IEE. vol.  120. 
 08 = half­ power beamwidth.  angle between the antenna-beam axis and the axis of rotation; and 88 is the half-power  beamwidth. The antenna beam shape is approximated by a gaussian function in the calcula­ tions leading to Fig. 
 /  / /  /  (b) -... ' TRACKING RADAR 157  Figure 5.4 (a) Pulse train with coni­ cal-scan modulation; (h) same pulse  train after passing through boxcar  generator.  not, it may be necessary to provide additional filtering to attenuate undesired cross­ modulation frequency components. 
 A filter bank covering the doppler  frequency range is of advantage in some radar applications and offers another option in the  design or MTI signal processors. Consider the transversal filter that was shown in Fig. 4.11 to  have N -1 delay lines each with a delay time T = 1/f,,. 
 VENTIONAL ALTIMETER INTO VERY LARGE HEIGHT ERRORS &OR EXAMPLE  AN UNKNOWN  n SLOPE  WOULD LEAD TO A  
 AES. 135.Punnett. M.S.:Developments inGround Mounted AirSupported Radomes, [EEE1977Mechanical Engineering inRadarS}'mpOsiIll11. 
 This is illustrated in Figure 13.1.  . Radar System Engineering  Chapter 12 – Selected Radar Applications  136     -0,4-0,200,20,40,60,811,2 -15 -10 -5 0 5 10 15Beam 1 Beam 2   θ         Figure 13.1  Example directivity patterns of monopulse Radar in the θ and ψ planes, intercept  points 3 dB. 
 21-23, l975, IEEE Publication 75 CHO 938-1 AES.  24. Cook, C. 
 BLES &IGURE   SOMETIMES &IGURE   AND SOMETIMES NEITHER  SO THESE STRAIGHT LINES COVER UP CONSIDERABLE UNCERTAINTY )N FACT  IT APPEARS THAT THERE IS NO SIMPLE FUNCTIONAL DEPENDENCE OF SEA CLUTTER ON WIND SPEED THAT CAN BE ESTABLISHED WITH ANY CONFIDENCE FROM EXISTING DATA  ALTHOUGH MOST INVESTIGATORS WOULD PROBABLY AGREE THAT THE BEHAVIOR OF MICROWAVE SEA CLUTTER WITH WIND SPEED AT INTERMEDIATE GRAZING ANGLES CAN BE ROUGHLY DESCRIBED AS FOLLOWS FOR LIGHT WINDS LESS THAN  TO  KT  SEA CLUTTER IS WEAK  VARIABLE  AND ILL DEFINED FOR INTERMEDIATE WINDS ABOUT  TO  KT   IT CAN BE DESCRIBED ROUGHLY  BY A POWER LAW OF  THE TYPE FOUND IN &IGURE  AND FOR  STRONG WINDS ABOVE ABOUT  KT   THERE IS A TENDENCY FOR IT TO LEVEL OFF )N FACT  THE CONVERGENCE OF THE LINES IN &IGURE  A B WITH INCREASING WIND SPEED SUGGESTS THAT  THE REFLECTIVITY OF THE SEA SURFACE IS TENDING TOWARD ,AMBERTS LAW  FOR WHICH THERE IS NO DEPENDENCE ON GRAZING ANGLE  FREQUENCY  OR POLARIZATION BUT ONLY ON SURFACE ALBEDO  OR AVERAGE REFLECTIVITY )N SEVERAL OF THE EXPERIMENTS REFERENCED ABOVE  THE DEPENDENCE OF SEA BACKSCATTER  ON ANGLE RELATIVE TO THE WIND DIRECTION WAS FOUND BY RECORDING THE RADAR RETURN FROM A SPOT ON THE SURFACE WHILE FLYING AROUND IT IN A CIRCLE &IGURE  A B GIVES AN EXAMPLE  OF THIS BEHAVIOR FOR GRAZING ANGLES OF ABOUT  AND WIND SPEEDS CLOSE TO  KT  4HE  FIGURES CONTAIN RESULTS OBTAINED INDEPENDENTLY BY THREE DIFFERENT GROUPS 4HE BEHAVIOR SHOWN HERE IS REPRESENTATIVE OF THAT FOUND GENERALLY SEA CLUTTER IS STRONGEST VIEWED UPWIND  WEAKEST VIEWED CROSSWIND  AND OF INTERMEDIATE STRENGTH VIEWED DOWNWIND  THE TOTAL VARIATION BEING ABOUT  D" /THER STUDIES CORROBORATE THIS BEHAVIOR &)'52%   %XAMPLE OF FORCING A POWER 
 When  the a priori probabilities are not known, the likelihood-ratio test is usually employed.  Relationship of inverse probability and likelihood-ratio receivers. The receiver input y may be  either signal-plus-noise or noise alone. 
 CONTROL TUBES AT THE HIGHER FRE 
  
 PERTURBATION METHOD 30-  AND ASSO 
 Kelvin Hughes has retained its name and Decca is incorporated  into the Sperry Marine organization of Northrop Grumman Corporation. The 1948  Kelvin Hughes Type 1 radar had a peak power of 30 kW, 0.2 µs pulse width, and a  PRF of 1,000 Hz. The 5 ft (1.5 meter) cheese antenna had horizontal and vertical  beamwidths of 1.6° and 11°, respectively, rotating at 30 rpm. 
 BY 
 An increase in  the number and severity of magnetic storms and sudden ionospheric disturbances is  another consequence of higher solar activity, as are increased post-sunset plasma bub - ble activity and associated scintillation in equatorial regions, solar flares, and coronal  mass ejections all of which disrupt stable propagation. Solar flares are giant explosions  on the sun’s surface, generally occurring near sunspots, which emit ionizing radiation  that penetrates into the D region and dramatically increases absorption. The resulting  sudden ionospheric disturbance (SID) or short-wave fade-out  can completely inca - pacitate a skywave radar for a period from minutes to hours. 
 If the mean is not zero, but  sonie other value to, the integrand in the numerator of (1 1.28) would be (2n)*(t - to)*s2(t). In  radar, the measurement error specified by Eq. (11.27) is that of the doppler frequency shift. 
 and M. I. Skolriik: Over-the-Iiorizon Radar in tlic f1F Hand. 
 NOISE RATIO  +0 USUALLY IS CITED AS A PERCENT   WHERE VALUES OF  OR BETTER ARE THE OBJECTIVE .OTE FOR HIGH 3.2 THAT  +0 CONVERGES  TO .4" !T LOWER WIND SPEEDS  +0 DEPENDS ON 3.2 AS WELL AS ON THE NUMBER OF  STATISTICALLY INDEPENDENT LOOKS 4HE DETAILS OF ANY EXPRESSION SUCH AS THIS DEPEND ON  THE UNDERLYING STATISTICAL MODEL  WHICH IS GAUSSIAN IN THIS CLASSIC EXPRESSION (OWEVER  THE GENERAL PRINCIPLE IS THAT THE SCATTEROMETER MUST PROVIDE MANY INDEPENDENT LOOKS TO REDUCE THE STANDARD DEVIATION OF THE  R    MEASUREMENT  REGARDLESS OF THE STATISTICAL  DISTRIBUTION OF THE OCEANS BACKSCATTER 4RENDS 6ECTOR WIND DATA HAVE BEEN ADOPTED BY OPERATIONAL METEOROLOGICAL  AGENCIES SUCH AS %5-%43!4 )T IS LIKELY THAT SPACE 
 Figure 16.17 shows some examples of the effect of the angle of inci - dence on the number of independent samples for a horizontally traveling scatterometer  with a forward-pointed beam. Study of the results obtained in this type of analysis indicates that, in regions  where the scattering coefficient does not change rapidly with angle, the widest pos - sible angular width (obtained by a longer pulse or a wider filter for a CW-doppler  system) gives the maximum number of independent samples for a given distance  traveled along the ground. FIGURE   16. 
 TATIONS ARE NOT AVAILABLE FOR NEWER DATA !CCORDINGLY  &IGURE  SHOWS AN EARLIER SUMMARY BASED MOSTLY ON 8 
 FEED REFLECTOR CONFIGURATIONS UTILIZING HORN  WAVEGUIDE   AND DIPOLE FEEDS &IGURE  SHOWS A FEW COMMON TYPES OF FLARED HORN FEEDS   &)'52%   3OME TYPICAL REFLECTOR ANTENNA CONFIGURATIONS. £Ó°ÓÈ  2!$!2 (!.$"//+  /THER TYPES OF FEEDS SUCH AS DIPOLES  MICROSTRIP PATCHES  NOTCHES  ETC  ARE SOMETIMES  USED  BUT FOR SINGLE 
 The wider the antenna, the narrower the beamwidth and the better the accuracy. The angle of arrival, or target direction, is not strictly a radar measurement (as are the range and radial velocity) if a radar measurement is defined as one ob- tained by comparing the reflected echo signal with the transmitted signal. The determination of angle basically involves only the one-way path. 
 ENT PLANETARY BODY )T IS OFTEN SAID THAT RADAR IS hALL 
 Int. IEEE Symp. Antennas Propagat ., July 10–12, 1974. 
 LEL 
 (11.3). Figures 11.28 and 11.29 compare measured and GTD-predicted RCS patterns of a right circular cone frustum. The theory replicates most of the pattern fea- tures for both polarizations but fails in three different aspect angle regions. 
 ING WAY   BGKK KTKJ KJ'R 
 The relative phase excitation caused by these  feeds is a known function of frequency. In these cases, the computer must provide  a correction based on the location of the element in the array and on the frequency  of operation. For a large array with thousands of elements, many calculations are required to  determine the phasing of the elements. 
 Thus  target detectability would improve in and near the strong clutter areas even though the  MTI improvement factor was still limited to 30 dB by internal-clutter motion. In summary, the noise-like pulse compression sidelobes and the duration of the  uncompressed pulse dictate how effective a pulse-compression MTI system can be.  Systems have been built in which transmitter noise and long uncompressed pulses  combined to make the systems incapable of detecting aircraft targets in or near land  clutter. 
 PGIT-4, pp. 17 1-2 12, September, 1954.  25. 
 117. sensors Communication SPARX, a MIMO Array for Ground-Based Radar Interferometry Alberto Michelini1,*, Francesco Coppi1, Alberto Bicci1and Giovanni Alli2 1IDS GeoRadar, 56121 Pisa, Italy; francesco.coppi@idsgeoradar.com (F.C.); alberto.bicci@idsgeoradar.com (A.B.) 2IDS Ingegneria Dei Sistemi S.p.A., 56121 Pisa, Italy; g.alli@idscorporation.com *Correspondence: a.michelini@idsgeoradar.com Received: 13 November 2018; Accepted: 5 January 2019; Published: 10 January 2019/gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: Ground-Based SAR Interferometry (GB-InSAR) is nowadays a proven technique widely used for slope monitoring in open pit mines and landslide control. Traditional GB-InSAR techniques involve transmitting and receiving antennas moving on a scanner to achieve the desired synthetic aperture. 
 It does not correspond to any particular set of experimental  data, but it represents what mighi be i)pi&l of "average" conditions. It was derived from a 2  body of data that extended from 10- to 20-knot wind speeds. (The uncertainty of the data  ought to have been indicated in thiq figure by making the vertical thickness of each curve at  least +3 dB wide. 
 Since the operation of such radars takes place either by the ground wave or over ionospheric (sky-wave) paths spanning great ranges, the grazing angles tend to be small (between O and 20°). For these wavelengths and grazing angles, initial measurements by Crombie indicated that the scattering from the sea surface was the result of Bragg scatter from sea waves of one-half the radar wavelength.4 In the years since these early measurements, there has been considerable activity in the field of HF radar and HF clutter,43'44 and the results can be summarized as follows: For vertical polarization, the major energy of the HF clutter signal appears in spectral lines displaced to either side of the . GRAZING ANGLE (degrees) FIG. 
 PHASE  % 
 Ryde, Attenuation of Centimeter Waves by Rain, Hail, Fog, and Clouds ,  Wembley, England: General Electric Company, 1945. 46. B. 
 HORIZON RADAR SYSTEM v  #ONF !IR 0OWER IN THE $EFENCE  OF !USTRALIA  !USTRALIAN .ATIONAL 5NIVERSITY  2ESEARCH 3CHOOL OF 0ACIFIC 3TUDIES  3TRATEGIC AND  $EFENCE 3TUDIES #ENTRE  #ANBERRA  !USTRALIA  *ULY n     * 7YLDER  h4HE FRONTIER FOR SENSOR TECHNOLOGY v  3IGNAL  VOL   PP n    6 ! 9AKUNIN  & & %VSTRATOV  & ) 3HUSTOV  6 ! !LEBASTROV  AND 9 ) !BRAMOVICH  h4HIRTY YEARS  OF EASTERN /4( RADARS HISTORY  ACHIEVEMENTS AND FORECAST v  ,/NDE %LECTRIQUE  VOL   NO    -AYn*UNE .   (& /6%2 
 The VA-87E, shown in Fig. 6.10, is a 6-cavity, S-band  klystron tunable over the range from 2.7 to 2.9 GHz. It was designed to meet the requirements  for the ASR-8 Airport Surveillance Radar. 
 The radar receiver has an equivalent bandwidth of 300 MHz to 3 GHz and  an equivalent receiver noise voltage of 2.49.10–5 volts. The probability of detection (PD) is derived from the error function of the signal-to- noise ratio, as shown in Figure 21.8. Note that these values only relate to the receiver  noise and do not include external sources of false alarms due to clutter . 
 Digital  beamforming59,60 is required for this operation. Other necessary elements include a  means to estimate the spatio-temporal clutter covariance matrix (the data-dependent  element of the filter weighting) and hypothesis of the target steering vector. In general,  auxiliary data taken from range bins other than the cell under test is used to estimate  the unknown, but critical, clutter covariance matrix. 
 The plot of the observed quantities as a function of the  load conductance and susceptance, for a fixed magnetic field and anode current, is called a  Rirke diagram, or a load diagram. .. An example of the coaxial magnetron performance characteristics is shown in Fig. 
 SHIFTERBITS  ,OSSING0 AAIN D"   $'   &ROM THE POINT OF VIEW OF GAIN  THEREFORE   OR  BITS WOULD APPEAR AMPLE 2-3 3IDELOBES  0HASE QUANTIZATION DECREASES THE GAIN OF THE MAIN BEAM  AS  SHOWN ABOVE 4HE ENERGY THAT HAS  BEEN LOST IS DISTRIBUTED TO TH E SIDELOBES 4HE RESULT 
 Weiss, “Analysis of some modified cell-averaging CFAR processors in multiple-target situa - tions,” IEEE Transactions on Aerospace and Electronic Systems,  vol. AES-18, no.1, pp. 102–144,  January 1982. 
 Evans Daniel Davis Electronic Systems Group Westinghouse Electric Corporation 6.1 INTRODUCTION Role of the Antenna. The basic role of the radar antenna is to provide a transducer between the free-space propagation and the guided-wave propagation of electromagnetic waves. The specific function of the antenna during transmission is to concentrate the radiated energy into a shaped directive beam which illuminates the targets in a desired direction. 
 vol. AES-14, pp. 199-208,  January. 
 3.32  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 3.11 EXAMPLE AMTI RADAR SYSTEM The AN/APY-9 radar, developed by Lockheed Martin for the U.S. Navy, is an example  of an AMTI radar system utilized for an airborne early warning radar mission. Key  features of this system include a solid-state distributed transmitter, a mechanically and  electronically scanned rotating antenna, digital receivers, space-time adaptive pro - cessing, digital pulse compression, and coherent integration and auxiliary processing  aimed at supporting the STAP sample selection process. 
 DAY MAPPING INTERVAL )N ORDER TO OFFSET THE TENFOLD ALTITUDE CHANGE ON 3!2 IMAGE QUALITY  THE 3!2 OPER 
 R. K.: Ionospheric Scintillation. Proc. 
 BASED 3!2 IS ITS ORBITAL ALTITUDE  USUALLY  KM OR HIGHER 4HE TYPICAL SLANT RANGE TO THE INTENDED SCENE MAY BE  KM AND MORE 4HUS  THE UPPER BOUND ON THE 02& SHOULD NOT BE SET BY THE RANGE TO THE SCENE  BUT RATHER BY THE RANGE WIDTH OF THE AREA TO BE IMAGED !S A CONSEQUENCE  THE RESULTING HIGH 02& WILL GENERATE A SEQUENCE OF PULSES AT ANY MOMENT THAT ARE DISTRIBUTED BETWEEN THE RADAR AND THE SCENE 4HE SPACE BETWEEN PULSES MUST BE LARGER THAN THE INTENDED SWATH WIDTH &OR EXAMPLE  IN CERTAIN MODES 2!$!23!4 
 S. V . Nghiem et al., “Polarimetric signatures of sea ice, 2, experimental observations,”   J. 
 McGraw-Hill Book Company. New York. 1970. 
 BASED DUCT 
 Aphased-array transmitting· antenna combines inspacethepowerfromeachofmany transmitting sources. Solid-state sourcesateachradiating element ofalargephased-array antenna canproduce thetotalpowerrequired formanyradarapplications. Theradiated beam issteeredbyelectronic phaseshifters.ateachelement, usuallyontheinputsideofthe individual poweramplifiers. 
 W. Houghton: Radar Tracking and Identification of Wild Duck During the  Aut urnn M iprat ion. I'roc. 
 Second, not all jammers are noise jammers. Some indeed have a structure in  range-doppler space, and CFAR techniques can potentially be used to lower these  unwanted signals beneath the detection threshold, once again preventing the detec - tion of false tracks, which—from a tactical perspective—can cause serious dilemmas  for a radar operator. Third, there are the adaptive CFAR detectors (AMF, or adaptive matched filter,  for example115) that really are ECCM techniques in the sense that they enhance the  probability of detection against structured interferences (in space and/or time) while  maintaining the constant false alarm rate property that allows these detected targets to  be effectively tracked, rather than being seduced by a high number of false detections. 
 5.6. The greater the slope of the error signal, the more accurate will be  the tracking of the target. The maximum slope occurs for a value (Jq/88 slightly greater than  0.4. 
 The Taylor is a practical approximation to the  Dolph-Chebyshev. A suitable waveform might be the cosine-squared on a pedestal, as in the  Hamming function, for example. The effect of weighting the received-signal spectrum to lower  the sidelobes also widens the main lobe and reduces the peak signal-to-noise ratio compared  to the unweighted linear FM pulse compression. 
 h–σpscurve. As shown in Figure 13,a s hincreases,σpsgradually rises. When h=100 m, theσpsrises to 6.96. 
 The propagation factor (F ,,). receiver noise (N 0), and coherent integration time (Yr) of  Eq. ( 14.22) represent major differences between the HF 0TH radar and the conventional  microwave radar. 
 Regenerative Trigger Circuits. —Three distinct methods have been proposed fortrigger regeneration. They differ inthe way inwhich the fraction ofamicrosecond inevitably lost inthetrigger amplifier ismade up inthedelayed signal channel. 
 TION TO THE APERTURE OR BY APPROXIMATING IT WITH A GABLE TRIANGULAR  PHASE DISTRIBUTION "EAMS OF THIS TYPE ARE OF PARTICULAR INTEREST BECAUSE THEY ARE EASILY GENERATED 4HEY MAY BE USED FOR TRANSMISSION IN A SYSTEM WHERE THE RECEIVING ANTENNA HAS A CLUSTER OF SIMULTANEOUS BEAMS  OR  AS PREVIOUSLY DISCUSSED  THEY MAY BE USED IN A SEARCH SYSTEM TO REDUCE THE NUMBER OF ANGULAR CELLS IN REGIONS OF SHORTER RANGE -ONITORING %LECTRONICALLY SCANNED ARRAYS ARE COMPOSED OF VERY MANY PARTS AND  INCLUDE ELECTRONIC CIRCUITRY TO DRIVE THE PHASE SHIFTERS OR SWITCHES THAT STEER THE BEAM 4HE OVERALL RELIABILITY OF SUCH ARRAYS CAN BE GREAT GRACEFUL DEGRADATION HAS BEEN CLAIMED BECAUSE THE FAILURE OF AS MUCH AS  OF THE COMPONENTS LEADS TO A LOSS IN GAIN OF ONLY  D" 4HERE IS  HOWEVER  A DEGRADATION OF LOW  SIDELOBES .EVERTHELESS  THE FUNCTIONING OF THE ANTENNA IS COMPLEX  AND THERE IS NEED FOR PROVIDING TEST OR MON 
 Thus it can rightfully be claimed that Sir Edward  Appleton, then of the University of Cambridge, not  only succeeded first in proving the existence of and  measuring the heights of the various ionized layers, but  by his radar-pulse measurements incidentally made the  very first measurements ever to be taken in radio range-  finding.  Watson-Watt was by 1933 Superintendent of the  Radio Department of the National Physical Laboratory,  and he was the man with vision to realize that this radio  range-finding system had potentialities of a limitless  degree. It would be entirely wrong to believe that all |  the preceding work of Appleton, Hollingworth, Gebhard, ;  . 
 68. Tang, C. H., et al.: Measurements of Electrical Properties of the Martian Surface, J. 
 The (half-power) width of the clutter spectrum is roughly the same for both polarizations and is equal approximately to the upwind vertical velocity given in Eq. (13.11). For look directions away from upwind, the peak doppler follows a cosine dependence very closely, going to zero at cross wind as- pects and turning negative downwind. 
 4.Collins, G.B.(ed.):..Microwave Magnetrons," MITRadiation Laboratory Series,vol.6,McGraw­ HillBookCo.,NewYork,1948. 5.Smith,W.A.:Ring-Tuned AgileMagnetron Improves RadarPerformance, Microwave SystemNews, vol.3,pp.97-102, February, 1974. 6.Clampitt, L.L.:Microwave RadarTubesatRaytheon, Electronic Progress, vol.17,no.2,pp.6-13, Summer, 1975. 
 The antenna pattern lobes caused by the presence of the ground might  sometimes be of advantage when the longest possible detection range is desired against low-  altitude targets and where continuous coverage is not required.  The simple form of the radar equation [Eq. (1.9)] may be written with the propagation  factor tl included to illustrate the effect of the plane earth:  P, ~~l~o 2nh, h, 41rP, G20(ha h,)4  Pr = (4n)'R4 - 16 sin4 - - lR 12R8 for small angles (12.8) 3  The received signal power for targets at low angles (on the lower side of the first lobe) varies as  the eighth power of the range instead of the more usual fourth power. 
 41,  pp. 1624-1631, November, 1953.  93. 
 Figure 10.11 shows the individual autocorrelation functions of the complementary sequences for length 26 and also the sum of the two autocorrelation functions. Golay28'29 and Hollis30 discuss general methods for forming complementary codes. In general, N must be an even number and the sum of two squares. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar.  GROUND PENETRATING RADAR  21.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 21 Where interfaces are spaced more closely than one half wavelength, the reflected  signal from one interface will become difficult to resolve with that from another. 
 9),orthe vertical dimensions oftheantenna must bereduced to fan the beam sufficiently inelevation totake account ofroll. Inair- borne PPI radar, the attainment ofsufficiently good display detail to permit navigation over land, away from distinctive shorelines, demands the use ofmicrowave frequencies. Infact, aconsiderable premium is placed onattainment ofthe narrowest azimuth beamwidth possible. 
 16. Cohen, W., and C. M. 
 The precise knowledge of the geometry of the acquisition allows to add in phase all the contributes of each single point scatterer on the ground present in the data to obtain the focused image. The wider the beam, the smaller the detail acquired by any return, but the larger the integration size of the track contributions to synthesize the image. The practical azimuth resolution is limited by the PRF choice (the Pulse Repetition Frequency of transmitted pulses used for coherent illumination of the target area), i.e., the azimuth sampling frequency. 
 of  voltage on the plates to deflect the beam, to increase  sensitivity. If we can afford to limit the possible ampli-  tude—i.e., the amount by which we need to deflect the  beam to produce a reasonable radar display on the  screen—then the plates may be placed quite close  together to increase the potential gradient between  them. That they cannot be too close is obvious, for in —  an extreme case the beam would touch one edge of the  plates at maximum deflection. 
 Smith: Propagation in an Evaporation Duct: Results in Some Simple Analytic  Models. Radio Science, vol. 7, pp. 
 The bandwidths are similar to those obtained  with the traveling-wave tube. Forward-wave Cf As generally have bandwidths from 10 to 25  percent; backward-wave CFAs, less than 10 percent. The gains are low or modest, but the  potential exists for higher gains, especially if trade-offs with other properties are permitted. 
 Especially the spaceborne SAR can achieve ground deformation monitoring in a wide range of scenes [ 6]. However, the spaceborne SAR systems and airborne SAR system require a long revisit cycle. They cannot realize continuous and repeated monitoring of a region. 
 Radar is used to extend the capability of one's senses for  observing the environment, especially the sense of vision. The value of radar lies not in being a  si~hstitute for the eye, but in doing what the eye cannot do-Radar cannot resolve detail as well  the eye, nor is it capable of recognizing the "color" of objects to the degree of sophistication  which the eye is capable. However, radar can be designed to see through those conditions  irnpervioris to normal human vision, such as darkness, haze, fog, rain, and snow. 
 For example, if the targets of  interest are airplanes, then a false track could be a track on a bird. (2) Tracks composed  of unrelated detections from different objects that the automatic tracking process has  mistakenly associated together. For example, a false track could be composed of detec - tions from several different stationary clutter points that have been associated together  over time to create a false moving track. 
  ZONE OF ACCESS WAS  FORWARD AND  TO EITHER SIDE OF THE SPACECRAFT GROUND TRACK &OR SELECTED MEASUREMENTS  THE BEAM WAS POINTED IN THE ALONG 
    0HYS 3CI 2ES  0APER     + 3 +ELLEHER AND ( 0 #OLEMAN  h/FF 
 PULSE FREQUENCY CHANGE IF A PULSED OSCILLATOR AND FROM PULSE 
 The radar cross section of aircraft targets is, in general, less with circular polarization than  with linear polarization. Experimental measurementss7 indicate that when an aircraft is illir-  minated with one sense of circular polarization, the echo power on a statistical basis is divided  more or less equally between right-hand and left-hand circular polarization. With linear  polarization, the amount of energy converted to the orthogonal polarization is about 0.5 dB. 
 It also included automatic frequency control (AFC) with the introduction of transmitter –receiver TR 3519B and an adjustable automatic attenuator rate control (attenuator type 58 and attenuator control unit type 492). Considerable dif ﬁculties were encountered in developing attenuator type 58. In addition, problems associated with modulator type 158, discussed above, and initial dif ﬁculties with scanner type 68 contributed to the considerable delays to the programme. 
 D. Cramp, and K. Curtis: Experimental Study of the Radar Cross-Section of  Maritime Targets, IEE (London) Jottrnal on Electronic Circuits and Systems, vol. 
 MITTER  RECEIVER  PROCESSOR  AND COMMUNICATIONS EQUIPMENT  AND THE OTHER CONTAINING A STANDBY GEN 
 8.42 Multisite Radar Integration  .................................  8.43  Unlike-Sensor Integration  ..................................  8.44  9. 
 Ifoperation withasinglepolarization ispermissible, thetechnique diagramed inFig.7.12 canreduceaperture blocking. Thesubreflector consistsofahorizontal gratingofwires,called atrallsre.flector, whichpassesvertically polarized waveswithnegligible attenuation butreflects thehorizontally polarized waveradiatedbythefeed.Thehorizontally polarized wavereflected bythesubreflector isrotated90°bythetwistreflectoratthesurfaceofthemainreflector. Thetwistreflectorconsistsofagratingofwiresoriented 45°totheincidentpolarization and placedone-quarter wavelength fromthe'reflector's surface.132(Modifications tothissimple designcanprovidea90°twistoftheincidentpolarization overabroadfrequency bandanda widerangeofincidentangles.2S.133) The\yavereflected fromthemainreflector isvertically polarized andpassesthroughthesubreflector' withnegligible degradation. 
 An example of clutter residue from simulated hard-limited distributed clutter is  taken from Hall and Shrader.32 Figure 2.67 shows a polar plot of part of a linear clut - ter sequence for a scanning radar with N = 20 hits per beamwidth. This linear clutter  sequence is 65 consecutive complex voltage returns from one range cell of distributed  clutter. Figure 2.68 shows the phase and amplitude of this sequence. 
 Inacertain sense, however, the use ofthe second channel inthis way more than doubles the number ofangular elements searched ina given time. That istosay, anisolated target can relocated inazimuth and inelevation with anaccuracy that would ordinarily require asharp “pencil” beam. But toscan the whole region with such apencil beam would take, according totheearlier discussion, avery much longer time. 
 It has also been suggested that the cross­ polarized component of the backscattered echo from simple axially symmetric objects (such as  disks, cones, and corie-spheres) can provide an estimate of a transverse dimension of the body  and give an indication of the severity of the edges, or "edginess."47 . EXTRACTION OF INFORMATION AND WAVEFORM DESIGN 437  Nonlinear-contact effects (METRRA).48 When metals come in contact with each other it is  possible for their junctions to act-as nonlinear ·diodes. The nonlinear properties of such  junctions can be used to recognize metallic from nonmetallic reflectors when illuminated by  radar. 
 This equation applies for pulse compression if 6, is the resolution of  the compressed pulse. It is seen from Eq. (14.16) that for a fixed signal-to-noise ratio, the  average power must be increased if the resolution in range or azimuth are decreased, or if the  range or swath are increased. 
 A   FILTER WITH CONSTANT GAINS SELECTED FOR THE APPLI 
 G.: Postdetectionlntegration Loss for Logarithmic Detectors, IEEE Trans., vol. AES-8,  pp. 386-388, May, 1972. 
 TRMM.  The Tropical Rainfall Measuring Mission was a joint undertaking  between NASA and the Japanese Aerospace Exploration Agency (JAXA). The five- instrument payload includes the Precipitation Radar151 (PR), which was designed and  built by JAXA (then NASDA), and was the first of its kind on a space-based platform. 
 One method of obtaining tracks with a surveillance radar is to have an operator manually  mark with grgase pencil on the face of the cathode-ray tube the location of the target on each  scan. The simplicity of such a procedure is offset by the poor accuracy of the track. The  accuracy of track can be improved by using a computer to determine the trajectory from  inputs supplied by an operator. 
 Most of the electronic scan phased array disadvantages are described in Chapter 13  and include losses in the array phase shifting elements, limitation of instantaneous  bandwidth with conventional phase control elements (improved with special true- time-delay phase shifting), phase quantization errors (Chapter 13) resulting from  phase shifting in steps, restriction to a single rf band (multiband arrays require special  techniques with major compromises), and gradual degradation of performance as the  beam is scanned from the normal to the array. The quantization errors from phase  shifting in steps are of concern to monopulse radar because it results in corresponding  random error steps in the electronic axis of the array. As described in Chapter 13, the  quantization errors are inversely proportional to the number of phase shifting elements  and 2P where P is the number of bits of phase control in each element. 
 Inanarray,however, otherfactorsmayentertocausedistortion oftheradiation pattern. Theseincludeerrorsintheamplitude aswellasthephaseofthecurrentatthe individual elements ofthearray,missingorinoperative elements, rotationortranslation ofan element fromitscorrectposition, andvariations intheindividual element patterns. These errorscanresultinadecrease ingain,increase inthesidelobes, andashiftinthelocation ofthe mainbeam. 
 Tl1c computed curves apply to  propagation over an idealized smooth earth in the absence of an atmosphere. The line or sight  is the straight-line distance hctwccn radar and target that is just tangent to the surface of the  earth. The distance between radar and target along the line of sight is  do )2kah; + )2kah2 ( 12.14)  where li1• lr2 heights or radar antenna and target. 
 77.Oliner,A.A.,andR.G.Malech: MutualCoupling inInfiniteScanning Arrays,..Microwave Scanning Antennas, vol.II,"R.CHansen (ed.),Academic Press,N.Y.,1966,chap.3. 7X.Stark,L.:Comparison ofArrayElement Types,..PhasedArrayAntennas, Proceedings ofthe1970 PhasedArrayAntenna Symposium," ArtechHouse,Inc.,Dedham, Mass.,1972,pp.51-67. 79.Knittel, G.H.:DesignofRadiating Elements forLargePlanarArrays: Accomplishthents andRe­ maining Challenges, Microwa/'e J.,vol.15,pp.27-34,September, 1972. 
 28. 1977. Washington, D.C. 
 TURE RADAR 3!2  SINCE BOTH USE THE DOPPLER SPREAD ACROSS THE ANTENNA MAIN BEAM TO CREATE HIGHER RESOLUTION IN THE CROSS BEAM DIRECTION     4HE PRINCIPAL DIFFERENCE IS  THE AMOUNT OF ANGULAR COVERAGE  BEAM SCANNING  RESOLUTION  DATA GATHERING TIME  AND ACCURACY OF MATCHED FILTERING IN EACH RANGE 
 BOUND PATH -ONOSTATIC RADARS WITH SEPARATE TRANSMIT AND RECEIVE ANTENNAS EXPERIENCE DECORRELATION BETWEEN THE PATHS AS THE SEPARATION INCREASES AND DIFFERENT PARTS OF THE IONOSPHERE BECOME INVOLVED %ITHER FORM OF MONOSTATIC RADAR AVOIDS THE COSTS OF MULTIPLE SITES AND ASSO 
 The problems  are related to the unwanted returns from birds, insects, automobiles, long-range  fixed clutter, and short- and long-range weather.53 The current state-of-the-art of  radar can ameliorate these problems, but not without some undesirable side effects.  (Many unwanted point target returns have characteristics similar to the returns from  wanted targets, and the unwanted returns may outnumber returns from desired tar - gets by the thousands.)  §  The clutter filters must be designed based on system parameters to reject the radial speed of the “fixed” clutter.  See Sections 2.4 and 2.6. 
 Phased arrays can be controlled adaptively, particularly for sidelobe  cancellation. This is an area where theory and understanding have advanced much.  Also great progress has been made with indoor near-field antenna ranges,16 where  computer-controlled precision two-dimensional radiation patterns are derived at mul - tiple frequencies and with scanning. 
 D.D.:SingleAperture Monopulse RadarMulti-Mode Antenna FeedandHoming Device, PrOf1964International ConI'.MilitaryElectronics. Sept.14-16.pp.259-263. 27.Sommer. 
 If the resolu­ tion of the radar is great enough to resolve the areas of lower clutter from the areas of greata  clutter, targets within the clear areas can often be detected and tracked even though it might be  predicted on the basis of the average clutter a0 that it would not be possible.  The ability of some radars to resolve the strong clutter regions into discrete areas, be­ tween which targets may be detected, is called i11Cercl11tta uisihility. It is difficult to establish a  quantitative measure of this effect; but it has been suggested~2 that the improvement in target  detectability can be approximated by the ratio of the average clutter level to the median  clutter, which can be as much as 20 dB for a medium-resolution radar (for example,6~ one with  a 2 ,,s pulse width and a 1.5° beamwidth). 
 A serious limitation of the laser is its inability to operate effectively in rain, clouds, or fog. 1.5 RADARNOMENCLATURE Military electronic equipment, including radar, is designated by the Joint Elec- tronics Type Designation System (JETDS), formerly known as the Joint Army- Navy Nomenclature System (AN System), as described in Military Standard MIL-STD-196D. The letter portion of the designation consists of the letters AN, a slant bar, and three additional letters appropriately selected to indicate where the equipment is installed, the type of equipment, and the purpose of the equip- ment. 
 1958.  51. Tollefson. 
 POWER SOLID 
 12. Vapnik, V .N. An overview of statistical learning theory. 
 A method  sometimes employed is to test the scintillation characteristics of the detected targets to  determine whether or not they follow those of real targets. Expendables that tend to be  designed under stringent economic constraints often return only a steady signal to the  radar. With doppler spectrum analysis, it is possible to look for returns from rotating  components of the target that any form of powered target must possess. 
 W .. A. W. 
  
 Theenergybackscattered frollltheseawilldependonthedirection ofthewindrelative tothedirection oftheradarantenlla beam.Itisgenerally higherwhentheradarbeamlooks intothewindthanwhenlooking downward orcrosswind. Theremightbefrom5to10dB variation in(10astheantenna scans)60"inazimuth. Ithasbeenfound4thatthebackscatter ismoresensitive towinddirection atthehigherradarfrequencies thanatthelowerfrequencies, thathorizontal polarization ismoresensitive towinddirection thanisvertical polarization, thattheratioof(10measured upwind tothatmeasured downwind decreases withincreasing grazing angleandseastate,andthatatUHFthebackscatter ispractically insensitive to winddirection atgrazing anglesgreaterthantendegrees, Whenviewing theseaatornearverticalincidence thebackscatter isgreatest withacalm seaanddecreases withincreasing wind.OllesetofdataSgivesthevalueof(f0atshortwave­ lengthstobeproportional toU-0.6,whereUisthewindspeed. 
 For  k = 0, the peak response of the filter occurs at f = 0, 1/T, 2/T, ... , which defines a filter  centered at de, the prf, and its harmonics. This filter passes the clutter component at de, hence  it has no clutter rejection capability. 
 Thecasewheref3=180°(forward scatter) isnotcovered bytheabovetheorem. The forward-scatter crosssectioncanbemanytimesthemonostatic (backscatter) crosssection. Siegelhasshownthattheforward-scatter crosssectionofatargetwithprojected areaAis Or=4nA2/)2,where), thewavelength oftheradiation, isassumed smallcompared withthe. 
 Furthermore, amplitude tapering can be accomplished by turning off or attenuating individual active array amplifiers. The general replacement of high-power microwave tubes by solid-state de- vices has proceeded more slowly than was once forecast. With hindsight, the rea- son for this is that it is usually too costly to use solid-state devices to replace a pulsed RF tube directly while operating at the same peak power and duty cycle. 
 Stark. L.: Comparison of Array Element Types," Phased Array Antennas, Proceedings of the 1970  Phased Array Antenna Symposium," Artech House, Inc., Dedham, Mass., 1972, pp. 51-67. 
 23, pp. 86-92, June, 1950.  18. 
   !54/-!4)# $%4%#4)/.  42!#+).'  !.$ 3%.3/2 ).4%'2!4)/.   Ç°Îx RESIDUALS GENERALLY INDICATE A MANEUVER A DEVIATION FROM THE FILTER MODEL  5PON  MANEUVER DETECTION  THE MANEUVER SPECTRAL DENSITY   Q  IS INCREASED IN THE +ALMAN FILTER  MODEL  RESULTING IN HIGHER TRACKING GAINS AND BETTER FOLLOWING OF THE MANEUVER ! MORE COMPLEX APPROACH IS TO USE MULTIPLE +ALMAN FILTERS RUNNING SIMULTANEOUSLY  WITH DIFFERENT TARGET MOTION MODELSGENERALLY  DIFFERENT  Q VALUES OR DIFFERENT EQUA 
 HIT RESULTS OF &IGURE  COULD BE MUCH TOO LARGE !N ANALYSIS OF THE PERFORMANCE OF TYPICAL IMPLEMENTATIONS OF CLUTTER MAPS HAS BEEN  DISCUSSED IN +HOURY AND (OYLE  &ROM THIS REFERENCE  A TYPICAL TRANSIENT 
 Radar System Engineering  Chapter 2 – EM Field Theory and Wave Propagation  9     From Maxwell’s equations it follows that all cartesian components of the field in a h omogenous,  isotropic, charge and current free medium (grad  ε = 0, grad µ = 0) and namely the instantaneous  values satisfy the Wave Equation:   € ΔA=1 c2∂2A ∂t2 (2.14)  The free -space propagation in the far field of the antenna is described by plane waves with the  Poynting vector    €   S =  E ×  H .  € E and  € H are in phase and they lie perpendicular  to each other.   Of interest for Radar technology is the position of the field components  € E and  € Hregarding the  media, on which they impinge. 
 20.6  to obtain an estimate of S( )k is mathematically nontrivial, requiring some additional  assumptions to obtain a unique, stable solution. Some of these methods address the  problem of full directional wave spectrum estimation,88–90 whereas others propose  estimators for integrated measures of sea roughness such as significant waveheight.91 Scattering coefficient (dB) Radar bearing with respect to wind direction (deg)−20 −25 −30 −35 −40 −45 −50Peak spectral bac kscatter coefficient 0 1 0 20 30 40 50 60 70 80 9 0semi-isotropic cos2 (f/2) cos4 (f/2) cos6 (f/2) Long and Trizna FIGURE 20.14  Variation of the peak backscatter coefficient as a function of wind direction relative to the  radar look direction for various spreading functions, assuming a sea fully developed at the Bragg-resonant  wave frequency ch20.indd   37 12/20/07   1:16:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 TATIONS TO CANCELLATION ARE LISTED BELOW      -ISMATCH BETWEEN THE MAIN AND AUXILIARY SIGNALS INCLUDING THE PROPAGATION PATHS   THE PATTERNS OF THE MAIN AND AUXILIARY ANTENNAS  THE PATHS INTERNAL TO THE SYSTEM UP TO THE CANCELLATION POINT  AND THE CROSSTALK BETWEEN THE CHANNELS n   4HE LIMITED NUMBER OF AUXILIARY CHANNELS ADOPTED IN A PRACTICAL SYSTEM AS COM 
 ACOUSTIC 
 An equally valid definition of  the RCS results when the electric-field strengths in Eq. 14.1 are replaced with the inci - dent and scattered magnetic-field strengths. It is often necessary to measure or calcu - late the power scattered in some other direction than back to the transmitter, a bistatic   situation. 
 The sense of the linear polarization of the energy radiated by the feed is  made the same as the orientation of the wires of the parabolic reflector. The feed in the center  of the figure illuminates the parabolic reflector· and the reflected energy is incident on a planar  mirror constructed as a twist reflector. As mentioned previously a twist reflector reflect<; the  incident energy with a 90" rotation of the plane of polarization. 
 Palmer, “The distribution of raindrops with size,” J. Meteorol ., vol. 4,   pp. 
 Sweep speed ..................v=2X10’cm/sec Note that d/u> r,which is Spot diameter ................d=O.lcm }notthebest condition, but isatypical one. conditions ofobservation. Signal occurs ononescan, atknown azimuth, in oneofsixrange positions. 
 POWER RADAR DESIGNED PRIMARILY FOR REMOTE SENSING IT IS AVAILABLE WITH AN UPGRADED PERFORMANCE OPTION 4HE OTHER RADARS SHOWN WERE DESIGNED FOR SURVEILLANCE )N ALL CASES  PERFORMANCE MAY FALL FAR SHORT OF THE CITED VALUES UNDER INCLEMENT ENVIRONMENTAL CONDITIONS  4!2'%4 490% 372   2AYTHEON  #ANADA(&372"!% 3YSTEMS  5+3%#!2  $ARONMONT  !USTRALIA0ODSOLNUKH 
 /\knowledge ofthetransmitted signalisnecessary atthereceiver siteifthemaximum information istobeextracted fromthescattered signal.Thetransmitted frequency isneededto determine thedoppler frequency shift.Atimeorphasereference isalsorequired ifthetotal scattered pathlcngth(Dr+Dr)istobemeasured. Thefrequency reference canbeobtained fromthedirectsignal.Thetimereference alsocanbeobtained fromthedirectsignalprovided thedistance D"between transmitter andreceiver isknown.Iftheseparation between transmit­ terandreceiver issufficiently large.thedirectsignalwillbehighlyattenuated bypropagation lossesandmightbetooweaktobcdetectcd atthereceiver. (Thesignalscattered bythetarget willnotbehighlyattenuated ifthetargetliesabovetheradarlineofsight,butthedirectsignal mustovercome thelossesduetoitsover-the-horizon path.)Whenthedirectsignalisnot availabk atthcreceiver. 
 MER NOISE WILL EXHIBIT SPECKLE  IE  A BRIGHTNESS VARIATION FROM ONE RESOLUTION CELL TO ANOTHER )N ADDITION  BECAUSE A LARGE NUMBER OF NOISE SAMPLES ARE ADDED NONCOHER 
 -Ê"Ê 
 The drive motor runs at1725 rpm and iscomected bya7-to-1 gear reduction torun the rotor about 4rps. The azimuth data transmitter isacapacitive voltage divider connected toahigh-frequency oscillator. *-75 c , (a)~D D(b) c E D(c)D FIG.9,26.—Successive steps imagined infolding theSchwarzschild horn. 
 Video Arnpliliers.-One ormore stages ofvideo amplification follow thedetector. The form ofthevideo amplifier isdetermined largely bvthenumber and location oftheindicator tubes. Inanairborne radar setthere may beonly asingle indicator located near thereceiver, inwhich case the video amplifier isvery simple. 
 Since they both process returns across two beamwidths before  switching, the beam dwell time Tb is approximately 2( ∆qR)m RR / c and the stepping rate  is Tb−1. The approximation assumes negligible phase-shift delays and settling times. Moving Target Indication (MTI) can be used with any of these pulse chasing imple - mentations, as long as the receive beam precisely retraces its scan pattern on succes - sive sweeps to capture the same clutter samples over the MTI processing time. 
 In both effects, it is the path-length differ - ences that contribute to the bandwidth sensitivity of a phased array. For a parallel-fed  FIGURE 13.24  Aperture-fill-time parallel-fed array ( after J. Frank79 © Artech  House 1972 ) ch13.indd   38 12/17/07   2:40:37 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 In order to use the doppler radar for navigation purposes, a heading reference is required  to refer the antenna direction indication to some navigational coordinate system, such as true  north. A computer is also needed to integrate the velocity measurements so as to give tilt:  distance traveled.  The AN/APN-200 doppler navigation' radar used in the Navy's S3A aircraft, and the  similar AN/APN-213 in the Air Force's E3A (AWACS) operate at 13.3 GHz with 1 watt of  CW power obtained from a solidktate IMPATT diode tran~mitter.'~ The waveform is unmod-  ulated CW. 
 OUS VELOCITY AND THEN MUST PENETRATE VERY HEAVY RAIN  THUS DICTATING LONG WAVELENGTHS 2ADARS DESIGNED FOR STUDIES OF NONPRECIPITATING CLOUDS TYPICALLY USE SHORT WAVE 
 METER HORIZONTAL GRID  &OLIAGE 
 (20),  the sign of the first term on the right side must be reversed.] 43. A. Michaeli, “Equivalent edge currents for arbitrary aspects of observation,” IEEE Trans .,  vol. 
 TION FUNCTION !S THE DISPLACEMENT INCREASES  A LARGER PHYSICAL APERTURE SIZE IS REQUIRED TO PRODUCE THE DESIRED VIRTUAL APERTURE SIZE OWING TO BEAM SPREADING 4HIS CAN BE SEEN IN &IGURE  4HE EFFECTIVENESS OF THE CORRECTION VARIES WITH ELEVATION ANGLE SINCE THE  &)'52%  #0#4 CONCEPT SHOWING DISPLACEMENT OF THE PHASE CEN 
  AND ,2/        
 14).  The distance d to the horizon from a radar at height /1 may be shown from simple  geometrical considerations to be approximately  d = fi[aii (12.lla)  where ka is the effective radius of the earth and It is assumed small compared with a. Fork= 4,  Eq. 
 It is obvious from a technical point of view that nuclear prime power systems should be utilized for large SBR systems whenever high power is required.25-kWe SOLAR-ARRAY SYSTEMMAN100-kWe REACTOR POWER SYSTEM 100-kWe SOLAR-ARRAY-BATTER Y SYSTEM 25-kWe REACTORPOWER SYSTEM . 22.5 CRITICALISSUES A succinct treatment of selected critical issues is given here. The critical issues in the development of SBR include (1) system cost, (2) system survivability or vul- nerability, (3) system calibration, (4) antenna deployment and distortion, (5) on- board processing, and (6) nuclear prime power. 
 The rejection of rain echoes by a circularly polarized radar depends on the purity with  whicii circular polarization can be generated by a practical antenna, as well as the deviation  of the precipitation particles from a spherical shape.' l7 The cancellation of the orthogonal  polarization by an exceptionally well-designed, well-maintained antenna might be limited to  about 40 dB.79 TO achieve 40 dB of cancellation the voltage ellipticity ratio of the antenna  (ratio of the minor axis to the major axis of the polarization ellipse) must be 0.99, a difficult  value to achieve. For 24 dB cancellation, the ellipticity ratio must be 0.94. Cancellations in  excess of 30 dB have been achieved in light rain and in dry'sn~w.~~ However, cancellations of  only 15 dB or less are obtained from nonspherical precipitation such as heavy rain, from the  melting layer. 
 Apr. 21 23. 1975, pp. 
 When exactly on the centre line of approach, the two bursts of signals would appear to have equal strength. In an alternative blind approach system used in the Lucero II system [ 5] the beacon transmitted bursts (about 1/20 s duration) of pulses of different length from its two beams. The dash pulses were about 10 μs long and the dot pulses about 3 μs. 
 2%& /35 2EFLECTOR #ODE  4HE 3!4#/- 7ORKBENCH IS  AVAILABLE TO MEMBERS OF THE 53! 3ATELLITE )NDUSTRY #ODE #ONSORTIUM 4)#2! '2!30 IS A GENERALIZED 0/ 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.6 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 The three-channel amplitude-comparison monopulse tracking radar is the most  commonly used monopulse system. 
 Janza has reported details of calibration problems with a range-measuring pulsed radar scatterometer.60'61 CW-Doppler Scatterometers. A convenient way to measure the scattering coefficient at many angles simultaneously is with a CW system in which the relative velocities corresponding to different angles are separated by separating their doppler frequencies. The use of a fan beam with such a system permits the simultaneous measurement of scattering coefficients at points ahead of and behind the aircraft carrying the radar. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.62  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 The calibration constants are then modified in order to restore the antenna so its  calibration is as close as possible to the original factory calibration. 
 The transmitter power supply could not meet this requirement when  the radar changed PRF from CPI to CPI, as required by an MTD waveform. Therefore,  the actual phase of each transmitted pulse was measured, and this measured value was  used to correct the phase of the received signals for that PRI. This technique causes  small perturbations in phase from weather signals received from ambiguous ranges,  but does not interfere with velocity estimates. 
 AMPLITUDE SIGNALS ARE RECEIVED FROM THE RADAR THE TRUE TARGETS ECHO AND AN 2'0/ 
 44.VanVleck,J.H.:TheAbsorption ofMicrowaves byOxygen, Phys.Rev.,vol.71,pp.413424, Apr.I. 1947. 45.VanVleck,J.H.:TheAbsorption ofMicrowaves byUncondenscd WaterVapor,Phys.Rev.,vol.71. 
 DIMENSIONAL ARRAY OF COMPLEX NUMBERS   IE  EACH CONSISTS OF A MAGNITUDE AND A PHASE 4HIS ORDERED ARRAY OF COMPLEX NUMBERS  AS A FUNCTION OF DOWNRANGE AND CROSSRANGE PRODUCES A COMPLEX RADAR  IMAGE  IE  EACH  PIXEL CONSISTS OF A MAGNITUDE AND A PHASE 4YPICALLY THE MAGNITUDE SQUARED REPRESENT 
 BASED 3!2 SEE 4ABLE     WAS LAUNCHED ONLY A DECADE LATER 4HAT WAS A REMARKABLE ACHIEVEMENT  CONSIDERING THAT IN THE MODERN ERA  IT OFTEN TAKES NEARLY  YEARS TO GO FROM CONCEPT TO LAUNCH OF A NEW 3!2  EVEN THOUGH THE PRINCIPLES AND TECHNOLOGY FOR THESE 3"2S ARE BY NOW WELL ESTABLISHED  1UILL WAS RUDIMENTARY  BUT DID SUCCEED IN GENERATING DATA SUFFICIENT TO FORM IMAGES 4HE NOMINAL  
 Theradarshouldhedesigned conserva­ tivelywithlargerpowerandlargerantenna aperturc thantheminimum required formarginal detcction. Oneofthebettermeasures againstmao)irorrl1s ofEeMisanalert,highlymotivah:d, well trained, andexperienced operator. Noisejamming. 
 1951.  29. Ringwalt. 
 CLUTTER RATIOS BUT ALSO BY COMPARING THEIR INHERENT RANGE SENSITIVITY 3UCH A PROCEDURE REVEALS THE CHARACTERISTICS THAT CONTROL THE RADAR PERFORMANCE 4HE DESIGN OF A '02 SYSTEM IS DEFINED BY THE MODULATION TECH 
 M., M. B. Karelitz, and L. 
 43. Heidbreder, G. R., and R. 
 SIVE APPROACH AND MAY BE REQUIRED IF THE FREQUENCY SEPARATION IS VERY LARGE ! MORE COMMON APPROACH IS SEPARATION OF THE FREQUENCIES AT THE FIRST )&  AS THIS DOES NOT REQUIRE COMPLETE DUPLICATION OF THE 2& FRONT END OR THE FIRST ,/ SIGNAL 3EPARATE SEC 
 RACY TO DETERMINE LARGE 
 The chief difficulty insuch experiments isconnected with themeasurement oftherainfall, which ishomogeneous inneither time nor space. The dashed curves ofFig. 2.17 show theattenuation infogorclouds which, aswehave said, does not depend onthedrop diameter. 
 A complete glossary of terms in use in the ECM and ECCM  fields is found in the literature.8,11,13 24.3 ELECTRONIC WARFARE   SUPPORT MEASURES ESM usually consists of several detection and measurement receivers and real time  processor boards dedicated to the interception of radar emissions. The identification of  specific emitters is based on comparison with tactical or strategic ELINT.9,14–17 Emitter  location can be additionally provided through several methods such as triangulation  †  Since the publication of the second edition of this Handbook, the U.S. Air Force changed some of the EW terms we  have gotten used to over these many years. 
 Santa: Final Report on Anticlutter Techniques, General Electric Company Kept. R65EMH31, Mar. 1, 1953. 
 Stevens RCA Electronic Systems Department GE Aerospace 10.1 INTRODUCTION Pulse compression involves the transmission of a long coded pulse and the pro- cessing of the received echo to obtain a relatively narrow pulse. The increased detection capability of a long-pulse radar system is achieved while retaining the range resolution capability of a narrow-pulse system. Several advantages are ob- tained. 
 A. F.: Radornes atid Absorbers, chap. 32 of "Antenna Engineering Handbook," H. 
 K.: "Modern Radar System Analysis," Artech House, Norwood, Mass., 1988. 4. Barton, D. 
 Figures 9a and 10a show the two-dimensional imaging results and the azimuth impulse responses based on the Doppler parameters with errors, respectively, and there is no Doppler parameter estimation. It can be clearly seen that the images are seriously defocused, and the Doppler bandwidths of the three points after the deramping are still about 10 Hz, indicating that there are still signiﬁcant secondary phases, and the errors of the Doppler rates are very large. Figures 9b and 10b show the two-dimensional imaging results and the azimuth impulse responses by the basic MAM method, respectively. 
 35. Bussgang, J. J., and D. 
 SION  UNCERTAINTIES IN THE INTEGRATION OF ENERGY MAY ARISE DUE TO THE TRANSIENT RESPONSE  OF THE PULSE COMPRESSION FILTER 3IGNAL 
 In Fig. 4.5, the coherent reference is supplied by an  oscillator called the colio, which stands for coherent oscillator. The coho is a stable oscillator  whose frequency is the same as the intermediate frequency used in the receiver. 
 18.12 Use of retracted septum to shape the sum-signal E field. FIG. 18.13 AN/FPS-16 feed, front view. 
 It is common for short wavelength on- board aviation weather radars to not detect intense convective cells behind closer, high  attenuation thunderstorms.  Severe storms with high precipitation rates also cause high  attenuation even at 5-cm wavelengths, as noted by Hildebrand37 and Allen et al.38 In some meteorological radar applications, it is desirable to attempt to measure  attenuation along selected propagation paths. This is done because absorption is  related to liquid-water content and can provide useful information for the detection of  such phenomena as hail, in accordance with the dual-wavelength technique described  by Eccles and Atlas39 and Vivek et al.40 In the following subsections, quantitative expressions relating attenuation to  precipitation are given. 
 The isolation is limited by the diffraction of the electromag-  netic energy behind the fence. Greater isolation than that provided by a straight-edged fence  can be had by incorporating two continuous slots near to, and parallel with, the upper edge of  the fence to cancel a portion of the energy diffracted by the fence. The double-slot fence can  increase the two-way isolation by 20 dB or more.62  A fence can suppress the clutter seen by the radar, hut it produces other effects not always  desirable. 
 VELOCITY BLIND ZONES  CORRESPONDING TO &IGURE  WAVEFORMS &)'52%  (IGH AND MEDIUM 02& INTERLEAVE FOR ALL ASPECT DETECTION . x°ÓÓ  2!$!2 (!.$"//+  !N EXAMPLE COMPARISON OF (02& AND -02& AS A FUNCTION OF ALTITUDE FOR A GIVEN  MAXIMUM TRANSMITTER POWER  POWER 
 53. p. I 125, August, 1965. 
 Table 10.9 lists Taylor coefficients Fm and main-lobe widths for various sidelobe levels and selections of n.48 The table illustrates that, for low design sidelobe levels, F1 is much greater than IFml when m > 1, indicating that Taylor weighting is closely approximated by the cosine-squared-plus-pedestal taper. A larger value of F1 is required, however, in the latter case to yield the same sidelobe level. F1 = 0.426 (H = 0.08), corresponding to Hamming weighting, produces the lowest level, -42.8 dB, attainable with this function. 
 Radant, “Airborne radar and the three PRFs,” Microwave Journal ,  July 1983 and reprinted in M. I. Skolnik, Radar Applications. 
 Haralick, R. K. Moore, and A. 
 We simulated the sub SAR complex image for interference. The interferometric phase can be obtained by interference with the main SAR complex image and the sub SAR complex image. The interferometric phase image is shown in Figure 19. 
 — isfirst interrogated atmaximum range through avery narrow angular region. Astherange decreases, thesector ofinterrogation increases, but remains ofthe order ofmagnitude ofthe half-power beamwidth ofthe antenna until arange about one tenth ofmaximum isreached. There, assuming the side lobes ofthe antenna pattern tobeabout 20db down, side-lobe interrogation begins and grows with decreasing range. 
 pp.R64R66,November. 1974. X5.Barton. 
 It performs several purposes: (1) concentrates the radiated energy  ch01.indd   4 11/30/07   4:33:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 
 The outputs of the FIR filters are summed to produce the output signal y(m). This  architecture is beneficial as it provides an approach that can be easily parallelized at  rate FX / D.  pk(n) = h(k + nD)   k = 0, 1, …, D - 1 (6.50)            n = 0, 1, …, K - 1  Multi-Channel Receiver Considerations. 
 302 INTRODUCTION TO RADAR SYSTEMS  Air,, where t, is the rise time. For large signal-to-noise ratios the slope of the pulse corrupted  by noise is essentially the same as the slope of the uncorrupted pulse. From Fig. 
 The spacing s between the plates of the metal-plate lens must lie between 1/2 and A if only  the dominant mode is to be propagated. The index of refraction for this type of metal-plate  lens is  H  Direction. of Figure 7.19 Plan, elevation, and end  propagat~on views of a converging lens antenna  constructed from parallel-plate wave-  guide. 
 PULSE REPETITION FREQUENCY SCHEME  FOR MITIGATING VELOCITY AMBIGUITIES OF THE ./!! 0 
 A A    &OR EXAMPLE  FOR  0F    
 For either lobe pattern, theelectric field strength atthe target depends onthe phase difference between the direct and reflected beams, and so will vary nearly sinusoidally with the altitude ofthe target. Figure 6.21 isdrawn for antenna heights of35 ftand 23ft,onthe assumption of sinusoidal variation. Itshows the3 . 
 The resultant rms tracking error ss will be periodic at the  frequency fs- ft where ft is the frequency of the spectral line. The effects of amplitude noise on target detection and acquisition are of concern in  all types of radars,2 particularly at long ranges where the signal is weak. The amplitude  fluctuations can cause the signal to drop below the noise level for short periods of time,  thus affecting the choice of thresholds, acquisition scan rate, and detection logic.34–36 Angle Noise (Glint). 
 AGE IS CONTINUOUSLY PRESENT BETWEEN ANODE AND CATHODE  AND THE CURRENT IS TURNED ON BY APPLYING THE 2& DRIVE AND TURNED OFF BY PULSING THE CONTROL ELECTRODE 4HE CONTROL ELECTRODE CONSISTS OF A SEGMENT OF THE CATHODE STRUCTURE IN THE DRIFT REGION  4O PREVENT THE TUBE FROM STARTING WITHOUT 2& DRIVE  THE CATHODE MUST BE KEPT COOL ENOUGH TO PRE 
 The individual sea spikes,  however, will disappear with time and new spikes will appear at other locations. If it is possible  to observe the radar display for a sufficient period of time, the small targets can be recognized  since they will remain relatively fixed in amplitude while the sea spikes come and go. The  penalty paid for this procedure is a long observation time. 
 7.2 RADAREQUATION Perhaps the single most useful description of the factors influencing radar perfor- mance is the radar equation which gives the range of a radar in terms of the radar characteristics. One form of this equation gives the received signal power Pr as ^ = £§X4^X^ (M) The right-hand side has been written as the product of three factors to represent the physical processes taking place. The first factor is the power density at a dis- tance R meters from a radar that radiates a power of Pt watts from an antenna of gain Gt. 
 It is used, in  spite of these limitations, in some low-cost radars.  Balanced duplexers. The balanced duplexer, Fig. 
 This is especially true when the main beam views the  rel:--tively "cool" sky but the sidelobes view the "hot" earth. A portion of the lT\ain beam  might also view the relatively "hot" earth if pointed at or near the horizon.  The amount of noise which enters the antenna depends upon the entire antenna radiation  pattern, including the sidelobes and the type of objects they illuminate. 
 VALUED WEIGHTS FOR EACH DESIRED BEAM DIRECTION THESE ARE THEN APPLIED TO THE RECEIVER OUTPUTS BEFORE SUMMING TO FORM THE ADAPTED BEAMS 4HE REASON FOR THE EFFICACY OF ADAPTIVITY HERE IS THAT  AS REMARKED PREVIOUSLY  (& RADARS ARE ALMOST ALWAYS EXTERNAL NOISEnLIMITED 4HE AZIMUTHAL DIS 
   !&!, 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar.  TRACKING RADAR  9.396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 the image enters the antenna main beam, and the error is essentially that of a two- reflector target glint error following approximately the equation37  e h=+ + +21 22 2ρ ρ φ ρ ρ φcos cos (9.7) where e = error, same units as h, measured at the target range relative to the target  r = magnitude of surface reflection coefficient  h = height of target  f =  relative phase determined by geometry of direct and surface-reflected  signal paths, as shown in Figure 9.26. 
 Deep residual learning for image recognition. In Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition, Seattle, WA, USA, 27–30 June 2016; pp. 770–778. 
 pp. 160-163. SEE (London) Conference Publication No. 
 SEC. 9.15] SCIHEIGHT FINDER 301 Inactual fact, thefeed horn moves, notlinearly, but circularly. The rotating feature isachieved byfolding and bending thetrapezoidal plates, keeping them parallel with aminimum ofstretching, insuch away that thefeed base isrolled into acomplete annular aperture while theflared base isheld straight. 
 TO 
 Res. Rec. J. 
 It may even act as a communication system, directing high-gain beams toward distant receivers and transmitters. Complete flexibility is possible; search and track rates may be adjusted to best meet particular situations, all within the limitations set by the total use of time. The antenna beamwidth may be changed to search some areas more rapidly with less gain. 
 The major variant is for the purpose of describing the transmitter-receiver portions of a radar system for the cases of synthetic antenna generation alone as compared with the case of synthetic antenna generation com- bined with pulse compression. The signal-processing operations will be discussed later. The essential elements of a radar system useful in a synthetic aperture situa- tion are shown in Fig. 
 TO 
 Miller, and M. T. Weiss: Behavior and Application of Ferrites in the Microwave  Region, Be/I System Tech. 
 2.37  Reflection from a Rough Spherical Surface  ........  2.38  Specular-Reflection Roughness Factor  ..............  2.39 Spherical-Earth Reflecti on Geometry  ................. 
 Ingeneral, theextremely lowsidelobe antenna canbea bettersolution, ifthedesiredlowsidelobe levelscanbeachieved andmaintained economically. Inprinciple, theautomatic tracking radardiscussed inChap.5isanother example ofan adaptive antenna. Theaperture illumination issensedbyaconicalscanormonopulse feedand theantenna isrepositioned tomaintain thesignal-to-noise ratioamaximum. 
 Johnson. M. A.: Phased-Array Beam Steering by Multiplex Sampling, Proc. 
 G.M.Pjerrou, andA.R.Neureuther: RadarCrossSectionof aLongWire,IEEETrans.,vol.AP-17,pp.381-384. May,1969. 36.Dunn,J.H.,andD.D.Howard: TargetNoise,chap.28of"RadarHandbook," M.I.Skolnik (ed.~ McGraw-Hili BookCo.,NewYork,1970. 
 PULSE COMPRESSION RADAR  8.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 in an up-chirp waveform that would be a matched filter for a down-chirp transmitted  waveform. In Figure 8.7 b both the input transducer and the output transducer are dis - persive, which would result in the same impulse response as that shown in Figure 8.7 a.  For a given crystal length and material, the waveform duration for the approaches in  Figure 8.7 a and Figure 8.7 b would be the same and is limited to the time that it takes  an acoustic wave to traverse the crystal length. 
 PULSE STAGGERING  GOOD RESPONSE CAN BE OBTAINED ON ALL DOPPLERS OF  INTEREST ON EACH SCAN )N ADDITION  BETTER VELOCITY RESPONSE CAN BE OBTAINED AT SOME DOPPLERS THAN EITHER PULSE INTERVAL WILL GIVE ON A SCAN 
 Although the above are limitations to the phased arr!}y in radar, they are probably not  sufficiently serious to restrict its greater use. However, the major limitation that has limited the  widespread use of the conventional phased array in radar is its high cost, which is due in large  part to its complexity. The software for the computer system that is needed to utilize the  inherent flexibility of the array radar also contributes significantly to the system cost and  complexity. 
 Then, the number of false positive detections is reduced by applying: (1) unsupervised feature learning algorithms and (2) optical ﬂow algorithms that track the motion of objects across time in small regions of interest. There have been a number of change detection studies using thresholding [ 5–8], extreme learning machine [ 9,10], Markov random ﬁelds [ 11,12] and combinations of feature learning and clustering algorithms [ 13–19]. Optical ﬂow ﬁelds can be used to distinguish between objects that have actually moved between frames and those that are in the same location but are slightly misregistered. 
  %! %#!   % % &%"&%             
 S. Rutherford: The Sun as a Test Source for Boresight  Calibration of Microwave Antennas, IEEE Trans., vol. AP-19, pp. 
 SIGHT OPERATION ITS PERFORMANCE CAN BE SIGNIFICANTLY 3HIP $YNAMICS 2EPORTING )NTERVAL SECONDS  !T ANCHOR OR MOORED AND NOT MOVING FASTER THAN  KNOTS  7ITH A SPEED OF BETWEEN n KNOTS   7ITH A SPEED OF BETWEEN n KNOTS AND CHANGING COURSE       7ITH A SPEED OF BETWEEN n KNOTS    7ITH A SPEED OF BETWEEN n KNOTS AND CHANGING COURSE    7ITH A SPEED OF GREATER THAN  KNOTS     7ITH A SPEED OF GREATER THAN  KNOTS AND CHANGING COURSE   4!",%  !)3 0OSITION 2EPORTING )NTERVALS #OURTESY OF )-/ .   #)6), -!2).% 2!$!2   ÓÓ°Óx DEGRADED BY CLUTTER  AND ITS TRACKING CAPABILITY IS COMPROMISED WHEN TARGETS ARE CHANG 
 5“17 and having anenvelope which isasine wave of doppler frequency. 1Actually, thereceiver gate isnotopened until several microseconds after the transmitter isoff. Inthisway ground clutter duetonearby objects iseliminated.. 
 The antennas would be designed to operate in the 10- to 100-GHz range and main-HOOP/COLUMN TRAC RADIAL RIBANTENNAWEIGHT (Ib) . REFLECTOR DIAMETER (ft) FIG. 22.13 TRW antenna reflector weight estimate.51 tain rms deviation on the order of 10~5-diameter fabrication error. 
 GAINLOSS 
 DELAY PHASE SHIFTING   PHASE QUANTIZATION ERRORS #HAPTER   RESULTING FROM PHASE SHIFTING IN STEPS  RESTRICTION TO A SINGLE RF BAND MULTIBAND ARRAYS REQUIRE SPECIAL TECHNIQUES WITH MAJOR COMPROMISES   AND GRADUAL DEGRADATION OF PERFORMANCE AS THE BEAM IS SCANNED FROM THE NORMAL TO THE ARRAY 4HE QUANTIZATION ERRORS FROM PHASE SHIFTING IN STEPS ARE OF CONCERN TO MONOPULSE RADAR BECAUSE IT RESULTS IN CORRESPONDING RANDOM ERROR STEPS IN THE ELECTRONIC AXIS OF THE ARRAY !S DESCRIBED IN #HAPTER   THE QUANTIZATION ERRORS ARE INVERSELY PROPORTIONAL TO THE NUMBER OF PHASE SHIFTING ELEMENTS AND  0 WHERE 0 IS THE NUMBER OF BITS OF PHASE CONTROL IN EACH ELEMENT #ONSEQUENTLY   THE HIGH PRECISION TRACKING RADARS WITH TYPICALLY  TO  PHASE SHIFTERS AND FOUR OR MORE PHASE SHIFT BITS HAVE SMALL RESULTANT ELECTRICAL AXIS E RROR STEPS ON THE ORDER OF   MILLIRADIANS OR LESS 4HE ELECTRICAL AXIS ERRORS ARE ESSENTIALLY RANDOM AND CAN BE FURTHER REDUCED BY AVERAGING )NTENTIONAL DITHER OF PHASE STEPS MAY BE INTRODUCED TO AID IN AVERAGING 4HE OPTICALLY FED TECHNIQUE RESULTS IN FEED ENERGY SPILLOVER AROUND THE APERTURE  HOWEVER  THESE RESULTANT SPILLOVER SIDELOBES CAN BE ELIMINATED BY AN ABSORBING CONE BETWEEN THE FEED AND THE ARRAY APERTURE 4HE ABSORBING CONE IS OBSERVED IN THE !.-01 
 In the examples shown, 16 MHz illumi - nates ranges from 1300 to 3000 km, whereas 19 MHz illuminates ranges from 1650 to  2750 km whereas 22 MHz illuminates from 1950 to 2750 km. Hence, the farthest edge  of the footprint need not increase with frequency, depending on the prevailing iono - spheric conditions. In this example, a single ionospheric layer is considered. 
 CUBIC  SEGMENT MODEL OF THE IONOSPHERE v 2ADIO 3CIENCE  VOL   PP n    2 - *ONES AND * * 3TEPHENSON  h! VERSATILE THREE 
 OE-7, pp. 20–32, 1982. 155. 
 Alebastrov, and Y . I. Abramovich, “Thirty years  of eastern OTH radars: history, achievements and forecast,” L’Onde Electrique , vol. 
 AWCS-EEM-1, April 1961.  2. S. 
 ofcourse, bythe radiation pattern ofthe antenna—which spread sothat the intensity ofthe dis- turbance falls offwith theinverse square ofthedistance. 2.2. Antenna Gain and Receiving Cross Section. 
 This was a great accomplishment in its time. The  high power, high efficiency, good stability, and wide bandwidth (at high power) of the  microwave klystron amplifier have caused some radar design engineers to say that the  klystron should be the first microwave power source to consider when designing a new  high-performance radar. (There was, at one time, a single-cavity klystron oscillator  called the reflex klystron  that was of low power and mainly used as a receiver local  oscillator, but it has generally been replaced by solid-state devices and is not discussed  further in this chapter.) The klystron is an example of a linear-beam tube  because the direction of the dc  electric field that accelerates the electron beam coincides with the axis of the magnetic  field that focuses and confines the beam. 
 £°{{  2!$!2 (!.$"//+   # * +ESSINGER  3 - %LLIS  AND * 6AN!NDEL  h4HE RADAR ECHO CLASSIFIER A FUZZY LOGIC ALGORITHM FOR  THE 732 
 WAVE CIRCUIT TO TAKE INTO ACCOUNT THE SLOWING DOWN OF THE BEAM AS THE ENERGY IS EXTRACTED FROM IT 6ELOCITY TAPERING PERMITS EXTRACTING MORE OF THE ENERGY FROM THE BEAM AND  SIGNIFICANTLY IMPROVES THE POWER 
 ERROR 
 )T IS NOT ALWAYS CONVENIENT TO USE THE EXACT NUMERICAL FREQUENCY RANGE OVER WHICH A  PARTICULAR TYPE OF RADAR OPERATES 7ITH MANY MILITARY RADARS  THE EXACT OPERATING FRE 
 11.44  Radar Absorber s  ...............................................  11.46  11.6 Summary  ................................................................  11.51  12. 
 Exact  computations obtained from F. T.  Haddock, approximate curves based  on the Rayleigh approximation. 
 F. Lyons: Receivers with Zero Intermediate Frequency, Proc. IRE, vol. 
 Golshayan, “Calibration aspects of the APAR antenna unit,”  in IEEE International Conference on Phased Array Systems and Technology , May 21–25, 2000,  pp. 425–428. 108. 
 Huygens' principle maybeappliedinthefarfieldbydividing theplane waveacrossthecircularaperture intoagreatmanyspherical wavelets, allofthesamephase butofdilTerent amplitude. Tofindthefieldintensity atapointadistanceRfromtheantenna, theamplitudes ofallthewavesareaddedatthepoint,takingaccountoftheproperphase relationships duetothedilTerence inpathlengths.Thefieldintensity atadistance Risthus proportional to 2IT ro (21tR)E(R)=.f odO.foA(r,0)expjTrdr (7.18) where 1'0istheradiusoftheaperture. Foracircularaperture withuniformdistribution, the fieldintensity isproportional to E(1))=(ITdO(Oexp(.i21tisin1>cos0)1'dr=1tr~2JI(~)j~ (7.19) where ~=2h(ro/A) sin1>andJI(~)=first-order Besselfunction. 
 Venot, M. Younis, W. Wiesbeck, "Realisation of a Compact Forward Looking  SAR with Digital Beamforming on Receive Only", Frequenz, vol. 
 Multiple elevation (stacked) beams.Theuseofcontiguous beamsstackedinelevation hasbeen employed for3Dradar.Itissometimes calledastacked-beam radar.Itisagoodtechnique. 544 INTRODUCTlON TO RADAR SYSTEMS  from a fundamental point of view since it uses simultaneous pencil-beam radiation patterns  from a single aperture to cover the elevation angles of interest. Each beam can be considered a  separate radar. 
 4.5. The  significant differcricc bctwec~i this MTI cotifiguration and that of Fig. 4.1h is the manlier in  which the reference signal is generated. 
   v &INAL 2EP *0, $ 
 497-506.  July. 1970. 
 VANTAGE IS THAT A LOG CHARACTERISTIC CAUSES SPECTRAL SPREADING OF THE RECEIVED ECHOES )T WOULD NOT BE POSSIBLE TO MAINTAIN CLUTTER REJECTION IN AN -4) OR PULSE DOPPLER RADAR IF THE SPECTRUM OF CLUTTER ECHOES WERE TO SPREAD INTO THE SPECTRAL REGION IN WHICH TARGET RETURNS WERE EXPECTED    4HE MAIN MESSAGE IS THAT THE DYNAMIC RANGE PROBLEM IS IMPORTANT FOR THE REJECTION  OF JAMMER AS WELL AS CLUTTER  THE LATTER ALWAYS PRESENT IN A RADAR 4HUS  THE RECOM 
 -   )%%% 3TANDARD 2ADAR $EFINITIONS  )%%% 3TD n    P    $ # 3CHLEHER   -4) AND 0ULSED $OPPLER 2ADAR   .ORWOOD  -! !RTECH (OUSE  )NC      PP IXnX   & % .ATHANSON  2ADAR $ESIGN 0RINCIPLES  ND %D .EW 9ORK -C'RAW 
 Due to the geological characteristics of large natural moisture content, high compressibility, low strength, and poor structure of soft clay, roads built on soft clay subgrade are more prone to displacement and instability, especially under large tra ﬃc loads. Sensors 2019 ,19, 3073; doi:10.3390 /s19143073 www.mdpi.com /journal/sensors 229. Sensors 2019 ,19, 3073 Consequently, long-term surface deformation monitoring for infrastructure built on soft clay, after highway embankment settlement construction, is of considerable practical signiﬁcance to the prevention of transportation safety accidents and the assurance of highway construction quality [ 1,2]. 
   %3!   # 66 0RIRODA  2USSIA5KRAINE   3  , ((  66324-  53! '  )  ^ #  8 ((  66 %.6)3!4  %3!       # 66 OR ((  DUAL )'3 
 Boston: Artech  House, 1994.  5. A. 
 The  correction factors may then be related to V A TT with  sufficient accuracy via a set of linear expressions using  179 . MacArthur, Marth, Wall -The GEOSA T Radar Altimeter  a set of wave-height-dependent coefficients that have  been derived from waveform simulations (Fig. 7). 
 LIVED  OFTEN LASTING LESS THAN AN HOUR IT MAY BE EITHER SMOOTH OR PATCHY  IS SEASONALLY AND DIURNALLY VARIABLE  WEAKLY CORRELATED WITH SOLAR ACTIVITY  SHOWING A TENDENCY TO FAVOR LOW SUNSPOT NUMBERS  AND HAS MARKED VARIATION WITH LATITUDE &ROM THE PROPAGATION PERSPECTIVE  SPORADIC % HOLDS A SPECIAL PLACE AS THE LAYER PROVIDING THE MOST STABLE PROPAGATION OVER COHERENT INTEGRATION TIMES TYPICAL OF SKYWAVE RADAR "ECAUSE IT IS ONLY ^ KM ABOVE THE %ARTHS SURFACE  THE MAXIMUM RANGE THAT CAN BE REACHED VIA ONE 
 With horizontal polarization over a good reflecting sur- . face (such as the sea), the constructive interference between the direct wave and the wave reflected from the surface can result in a substantial increase in the maximum range against aircraft (almost twice the free-space range). However, a consequence of this increase in range due to constructive interference is that the accompanying destructive interference results in nulls in the coverage at other elevation angles and less energy at low angles. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 1.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 and safely controlling aircraft and airport vehicle traffic on the ground. 
 (One international nautical mile is exactly 1852 m.) The target cross section a is in square meters, transmitter power Pt in kilowatts, pulse length T in microseconds, frequency/in megahertz, and system noise temperature T5 in kelvins. (All other quantities are dimensionless.) If the range is desired in units other than nautical miles (all other units remain- ing the same), in place of the factor 129.2 the following numerical constants should be used in Eq. (2.11): detector, however, is a decision-making device—for example, a device that replaces the human observer of a cathode-ray-tube display—and in that context detection is the making of a positive decision. 
 The beam-shape loss is reduced by the ratio of  the square of the maximum antenna gain at which the pulses were transmitted divided by the  square of the antenna gain at beam center. The ratio involves the square because of the  two-way transit.  When there are a large number of pulses per beamwidth integrated, the scanning loss is  generally taken to be 1.6 dB for a fan beam scanning in one coordinate and 3.2 d R when  two-coordinate scanning is used.49-si  When the antenna scans rapidly enough that the gain on transmit is not the same as the  gain on receive, an additional loss has to be computed, called the scanning loss. 
 I.42  Index terms  Links   Solid-state transmitters:  advantages of 5.1  design examples of 5.23  microwave design of 5.12  for phased arrays 7.67  power combining in 8.23  system design of 5.21  Space-based radar (SBR):  advantages and disadvantages of 22.11  air-traffic control with 22.30  altimeter    22.3  antennas for 22.18  Cosmos 1500 22.17 22.18 22.23  costs of     22.26 22.27  coverage of 22.12  GEOS-C       22.15  GEOS-3       22.4  launcher capabilities for 22.10  for military systems 22.31  on-board processors for 22.24  orbit selection for 22.5  planetary observation 22.29  prime power for 22.24  radiation effects and 22.9  remote sensing with 22.3 22.29  rendezvous 22.3 22.14 22.26  scatterometer 22.4  Seasat       22.3 22.22  SAR for      22.15  Shuttle Imaging Radar (SIR) 22.15 22.22  thermal effects in 22.6  transmit-receive modules for 22.23  This page has been reformatted by Knovel to provide easier navigation. I.43  Index terms  Links   Space-based radar (SBR):  (Continued)  22.15 22.22  types of     22.1  Sparking in magnetrons 4.8  Spectral emissions of solid-state modules 5.22  Spectrometers 12.18  Speedgate    14.18 19.10 19.12  Sphere, radar cross section of 11.5  Spherical earth, reflec tion geometry with 2.41  Spotlight mode in SAR 21.21  Spurious output of transmitters 4.31  Squint mode in SAR 21.20  Stability:  in MTI radar 15.45  in pulse doppler radar 17.28  of transmitters 4.25  Stabilization in CW radar 14.8  Stabilized magnetrons 4.7  Stacked-beam height finder 20.7  accuracy of 20.32  Staggered PRF 15.16 15.34  and transmitter stability 4.27  Stalo        3.12 15.3  STC          3.17  and antenna pattern 6.31  and MTI radar 15.69  in pulse doppler radar 17.12  Storm warning 23.19  Stretch processor 10.8  Subarrays    7.61  amplitude quantization effects in 7.48  bandwidth of 7.53 7.57  This page has been reformatted by Knovel to provide easier navigation. I.44  Index terms  Links   Subarrays (Continued)  7.61  combining of power sources with 4.24  Subclutter visibility 15.13  Superresolution 9.16  Surface features in sea clutter 13.33  Surface reflections and height finding accuracy 20.32  Surveillance radar:  automatic tracking with 8.23  and ECCM     9.23  Swerling target models 2.21 8.17  and diplex operation 3.54  in pulse doppler radar 17.38  Synchronous detector 3.32  Synthetic aperture radar (SAR):  ambiguities in 21.14  and ambiguity function 21.8  antenna in 21.18  block diagram of 21.7  digital processing in 21.18  focused      21.6  inverse (ISAR) 21.21  motion compensation in 21.20  multiple beams in 21.21  optical processing in 21.18  phase errors in 21.17  principle of 21.1  and projection-slice theorem 21.22  radar equation for 21.16  recording in 21.19  resolution of 21.3  and ambiguity function in 21.11  This page has been reformatted by Knovel to provide easier navigation. 
 4. Van Voorhis, S. N. 
 By analogy to the linear-FM pulse-compression waveform, the linearly varying doppler  signal can be passed through a matched filter to produce a pulse of duration 1/t::..jj. This . OTHER RADAR TOPICS 527  corresponds to a cross-range. 
 Generally, higher-frequency devices exhibit higher EpIBa ratios; and to obtain a high EpIBa ratio very fine line geometries are required, where the term geometry refers to the surface construction details of the transistor. One limit on the RF power output capability of the transistor is the breakdown voltage of the collector-base junction. Within that limit, the maximum practical level of power output that can be obtained from a single transistor over a given bandwidth is governed by two further limitations: the thermal-dissipation limit of the device and the terminal input or output impedance limit of the device. 
 GPR will not penetrate metal because of the latter’s conductivity. There are now a number of commercially available equipments, and the technique  is gradually developing in scope and capability. Many GPR systems are mobile and  mounted on wheels or skids to be moved by hand, but systems can be used on vehicles  for rapid survey by means of an array of antennas. 
 Application to r~ieasurerrierit of sea cotiditions. The distinctive nature of the doppler freqilency  sl~il't fro111 tlie sea allows irilormation to be extracted regarding the.sea conditions at~d the  wrritls driving the sea.?*." Tlie major portion of the doppler-frequency spectrum from tire SC~  OTHER RADAR TOPICS533 Rangeresolution-could beaslowas2km,butismoretypically 20to40km. Relatil)e rangeaccuracy-typically.2.t04 kmforatargetlocation relativetoaknownlpcation observed bythesameradar. 
 The purpose of the quadrature channel is to eliminate the 1 i~itrodtrced into the col~o reference signal at the phase detector. This causes the outputs of the ,  \  \ efTects of hlitrd phases, as will be described later. It is desirable to eliminate blind phases in any  MTI processor, but it is seldom done with analog delay-line cancelers because of the complex-  ity of the added analog delay lines of the second channel. 
 Cha et al., “An RCS analysis of generic airborne vehicles’ dependence on frequency and  bistatic angle,” in IEEE Nat. Radar Conf ., Ann Arbor, MI, April 20, 1988, pp. 214–219. 
 FIELD 0/ CONTRIBUTION TO THE FAR FIELD WAS THE PART OF THE  '4$ PRESCRIPTION GIVING RISE TO SINGULARITIES IN THE  8 AND 9 OF %QS  AND    5FIMTSEV DEVISED A MODIFIED SET OF DIFFRACTION COEFFICIENTS BY SIMPLY SUBTRACTING AWAY . £{°ÓÈ  2!$!2 (!.$"//+  THE OFFENSIVE 0/ DIFFRACTION COEFFICIENTS FROM THE TIME 
 TION FUNCTION AS A FUNCTION OF RELATIVE TIME DELAY  T FOR DOPPLER SHIFTSp OF n -(Z    AND  -(Z  PULSEWIDTH  4    §S  SWEPT BANDWIDTH "     -(Z  AND ,&- SLOPE  @   "4    -(Z§S ! DOPPLER SHIFT OF  FD   "    -(Z CAUSES THE PEAK OF THE  CORRELATION FUNCTION TO MOVE TO  S    FD4"    §S &IGURE  SHOWS THE RESULT WHEN  THE PULSEWIDTH IS INCREASED TO  §S TO YIELD A WAVEFORM WITH AN ,&- SLOPE EQUAL  &)'52%    ,&- BANDPASS SIGNAL EXAMPLE SHOWN FOR  4    §S   "    -(Z    F    -(Z  -AINLOBE 7IDTH 4IME $ELAY 2ESOLUTION S  2ANGE 2ESOLUTION M     D" S   " $2   C"    D" S   " $2   C"    D" S   " $2   C"   D" S   " $2   C"4!",%    ,&- 7AVEFORM 4IME $ELAY AND 2ANGE 2ESOLUTION 7IDTHS p  4HESE VALUES OF DOPPLER SHIFT ARE LARGE FOR MICROWAVE RADARS AND WERE SELECTED TO SHOW THE EFFECT OF RANGE 
 G., I. M. Fuks, A. 
 assume that  a 30 radar with a one-degree pencil beam must cover 20 elevation beam positions and 360  azimuth beam positions (a total of 7200 beam positions) every four seconds. If there is but one  pulse per beam position, the pulse repetition frequency can be no less than 1800 Hz, which  corresponds to an unambiguous range or 83 km. This is a rather short unambiguous range for  an air-surveillance radar. 
 175 176. Jnrii~ary. 1965. 
 A. Farina, Antenna-based Signal Processing Techniques for Radar Systems , Chapter 3, Norwood,  MA: Artech House, Inc., 1992, pp. 59–93. 
 The electron beam, generated by an  “electron gun,” essentially flows in a straight line in linear-beam tubes to interact with  a microwave circuit to produce amplification of an input signal. The major difference  among the several types of linear-beam tubes is the type of microwave circuit employed  ch10.indd   4 12/17/07   2:19:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Uoublecancellation. Thefrequency response ofasingle-delay-line canceler (Fig.4.7)doesnot alwayshaveasbroadaclutter-rejection nullasmightbedesiredinthevicinityofd-c.The clutter-rejection notches maybewidened bypassingtheoutputofthedelay-line canceler through aseconddelay-line canceler asshowninFig.4.9a.Theoutputofthetwosingle-delay­ linecancelers incascade isthesquareofthatfromasinglecanceler. Thusthefrequency response is4sin2nfdT.Theconfiguration ofFig.4.9aiscalledadouble-delay-line canceler, or simplyadOlllJlecallceler. 
 38, pp. 754–765, 2000. 133. 
 The sensitivity of the technique peaks at the crossover angle and is sym- metrical about that angle, attaining a value at crossover which depends on the separation between the beams. A maximum crossover sensitivity of 1.95 is achieved for a w-space beam separation of 1.2. Coverage in u space provided by the uniform stacked-beam pair is approximately given by 2—Aw, where Aw is the w-space beam separation corresponding to a target in the main lobes of both beams. 
 A linear-FM waveform (chirp) of narrow  bandwidth Bl is mixed with a wideband chirp of bandwidth B2. The radiated signal is a chirp  of bandwidth Bl + B2. On receive, the signal is mixed with the same wideband chirp B2 to  give a chirp of narrow bandwidth Bt which is then processed as a normal pulse-compression  signal. 
 To meet these requirements, the filter requires 4-delay sections, which can be imple - mented as two cascaded 2-delay sections, as shown in Figure 2.46. FIGURE 2.46  Four-delay elliptic filter used in TDWR−a11 −a21x(n)b11 b21 Z−1Z−1G −a12 −a22b12 b22 Z−1Z−1y(n) H1(z) H2(z) ch02.indd   47 12/20/07   1:44:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 NAL VOLTAGE VREC ENTERING THE SYSTEM MAY BE WRITTEN IN VECTOR 
 K7 TRANSMITTERS AND ANTENNAS WITH MORE THAN  
 Sucharadarisknownasasidelooking radar,orSLR.Thex'sinthefigurerepresent theposilion oftheradaralltelllla eachlimeapulseistransmitted. Iftheechoreceived ateach position isstoredandifthelastnpulsesarecombined (addedtogether), theeffectwillbe similartoalinear-array antenna whoselengthisthedistance traveled duringthetransmission oftile/Ipulscs.The"clement" spacing ofthesynthesized antenna isequaltothedistance traveled bytheaircraftbetween pulsetransmissions, orde=vTp=vlf~,whereTpisthepulse­ repetition period and.l~isthepulse-repetition frequency. 517. 
 Kilgus, J. A. Perschy, J. 
 As the  ch17.indd   4 12/17/07   6:48:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 
 Thepulseduration canbefrom0.5to6.0tIS. TheVA-812C isawideband UHFklystron witha12percentbandwidth. Itiscapableof RMWofpeakpowerand30kWofaveragepower,withapulsewidthof6JJ.S.Itsefficiency is 40percentandgainis30dB.Apeakbeamvoltageof145kVisrequired. 
 414-464, September, 1968.  78. Dillard, G. 
 FORMS v )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS   VOL   NO   PP n   /CTOBER   & % .ATHANSON   2ADAR $ESIGN 0RINCIPLES   ND %D .EW 9ORK -C'RAW 
 These voltage samples are  corlverted to a series of digital words by the analog-to-digital (A/D) c~nverter.~~,~~ The digital  1, or tn- phase, channel  C Diqilol Sub-  converter - store tractor  From Magnitude -+  IF (1' + 02)"~ -  detector converter tractor  Q, or quadrature, channel  Figure 4.21 Block diagram of a simple digital MTI signal processor.  MTIANDPULSE DOPPLER RADAR119 MTIradarusingrangegatesandfiltersisusuallymorecomplex thananMTIwitha single-delay-line canceler. Theadditional complexity isjustified inthoseapplications where goodMTIperformance andtheOexibility oftherangegatesandfilterMTIaredesired.The bellerMTIperformance resultsfromthebettermatchbetween theclutterfiltercharacteristic andtheclutterspectrum. 
 CIVIL MARINE RADAR  22.316x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 Because of their number, such radars tend to be minimally adapted shipborne radars  as they offer adequate performance at relatively low cost. Interestingly, the IALA recommendations allow CCTV solutions to compete with  radar when there is very low traffic density. Automatic tracking of a single target is  then required. 
 Good practice dictates that the amplitude of the incident wave  deviate by no more than 0.5 dB over the transverse and longitudinal extent of the tar - get and that the phase deviation be less than 22.5°. It is standard practice at some test  ranges to physically probe the incident field at the onset of a test program to verify the  amplitude uniformity of the incident wave. The phase requirement is the basis of the far-field range criterion:  R > 2D2/l (14.20) where R is the distance between the instrumentation radar and the test object and D is  the maximum target dimension transverse to the line of sight. 
 D.: A Triangular Arrangement or Planar-Array Elements that Reduces the Number  Needed, IRE Trans., vol. AP-9, pp. 126-129, March, 1961. 
 thccoupling totheductisstronger andthe average (one-way) attenuation wasreported as0.45dB/nmi.J7UnlikeSband.theattenuation atXbandwaslessatlowantenna andtargetheights(Jto5m).givingstronger signalsand greaterrangesthanantennas andtargetsatheightsupto30m:whichisafurtherindication of effective trapping atthehigherfrequencies. Itwasobserved thatwithalargeenoughductmorethanonemodecanhepropagated andtherecanbemorethanoneantenna heightsuitahle forlow-loss propagation. For example.37onesetofX-banddatashowedtheminimum attenuation tooccurwithanantenna heightof2m.Increasing theantenna heightincreased thelosstoamaximum atabout10m height.Further increase ofheightdecreased theattenuation untilasecondary minimum was obtained at20mheight.afterwhichthcattcnuation againincreased (atleasttoaheightof 30m),Onashipitmightnothepractical tositearadarantenna 2moverthesea.Instead it mightbesitedat20mheight.withtheslightly greaterlossheingapricetopayrorthe convenience ofthehigherantenna location. 
 DIMENSIONAL PORTRAYAL OF THE RADAR BACKSCATTER RETURNING FROM THE FIELD ILLUMINATED IN RANGE AND AZIMUTH 3PACE 
 BASED .,&- WAVEFORM IN THE PRES 
 This video  is typically processed by a sample and hold circuit that charges a capacitor to the  peak video-pulse voltage and holds the charge until the next pulse, at which time the  capacitor is discharged and recharged to the new pulse level. With moderate low-pass  filtering, this gives the dc error voltage output to the servo amplifier to correct the  antenna position. FIGURE  9.3  Block diagram of a conventional monopulse tracking radar ch09.indd   5 12/15/07   6:07:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 An air-surveillance radar with a rotating antenna beam determines angle in  this manner. The angle to a target in one angular dimension can also be determined by  using two antenna beams, slightly displaced in angle, and comparing the echo ampli - tude received in each beam. Four beams are needed to obtain the angle measurement  in both azimuth and elevation. 
 DIELECTRIC STRIPLINE  IS EMPLOYED TO SUM THE MODULE OUTPUTS TO THE  K7 LEVEL , 
 W. H. Emerson and H. 
 Am. , vol. 78,  pp. 
 -Ê"Ê, ,- !LTHOUGH THERE IS NO SINGLE WAY TO CHARACTERIZE A RADAR  HERE WE DO SO BY MEANS OF  WHAT MIGHT BE THE MAJOR FEATURE THAT DISTINGUISHES ONE TYPE OF RADAR FROM ANOTHER 0ULSE RADAR 4HIS IS A RADAR THAT RADIATES A REPETITIVE SERIES OF ALMOST 
 D irective array ** Peak Power Output  .  100 kw Pulse Width   .  15-40 microsecond Pulse Repetition Rate  . 
 W. M., M. 8. 
 1977.  35. Moore. 
 It was in- stalled in the mid-1950s but was later removed.24 The Canadians also developed a bistatic radar for their McGiIl fence.29'32 The United States Plato and Ordir bal- listic missile detection systems were designed as the first multistatic radars; they combined range sum and doppler information from each receiver site to estimate target position. They were not deployed.24'32 The Azuza, Udop, and Mistram interferometeric radars, a variant of multistatic radars, were installed at the United States Eastern Test Range for pre- cision measurement of target trajections. They used a single CW transmitter, multiple receivers at separate, precisely located sites, and cooperative beacon transponders on the target.9'10 The SPASUR, a satellite fence interferometric ra- dar, was also implemented with a single CW transmitter and multiple receivers but with enough performance to detect satellite-skin echoes.7'8 A major development at this time was the semiactive homing missile seeker, in which the large, heavy, and costly transmitter could be off-loaded from the small, expendable missile onto the launch platform (Chap. 
 This radiation is related to atmospheric absorption, which is greater at low angles where the antenna beam sees a thicker slice of the lossy atmosphere than it does at higher angles. Curves of antenna temperature for a lossless antenna are shown in Fig. 2.9, calculated for typical conditions.14'25 FIG. 
 TO 
 l)  This is a conservative definition since the RF drive power is not lost but appears as part of the  output. 212 INTRODUCTION TO RADAR SYSTEMS  The low insertion loss of a CFA can be of advantagc in systems that require more than  one radiating power level.-By omitting the-application of d-c voltage to the final stage, the  lower level RF drive-power can be fed through the final stagi.: with littlc atti.:nua1ion. This  allows two power levels, depending on whether the final CF A stage has d-c voltage applied or  not. 
 ● HF over-the-horizon radar that extended the range of detection of aircraft and ships  by an order of magnitude. ● Digital processing, which has had a very major effect on improving radar capabili - ties ever since the early 1970s. ● Automatic detection and tracking for surveillance radars. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar. 9.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 gear backlash. 
 4.h.  55. Scvcrin, 1-i.: Nonrellccting Absorbers (or Microwave Radiation, IKE 'i't.trr~.s., vul. 
 1.4 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 missile to a target; or the radar output might be further processed to provide other  information about the nature of the target. The radar control  insures that the various  parts of a radar operate in a coordinated and cooperative manner, as, for example,  providing timing signals to various parts of the radar as required. The radar engineer has as resources time that allows good doppler processing,  bandwidth  for good range resolution, space  that allows a large antenna, and energy  for  long range performance and accurate measurements. 
 The third source is  typically caused by shadowing, for example, by an aircraft fuselage blocking one of  the bistatic paths—transmitter or receiver LOS to a scattering center . In general, this divergence results in a bistatic RCS lower than the monostatic RCS  for complex targets. For example, Ewell and Zehner81 measured the monostatic and  bistatic RCS of coastal freighters at X band when both the transmitter and the receiver  were near grazing incidence. 
 VIA and, using an adjustable link, H 2S Mk. III. The IF gain was controlled from the switch unit. 
 The receiver must deliver amaximum ofdesirable, and aminimum ofundesirable, information toihe indicator. Itshould have aslittle inherent noise aspossible, Since such noise determines theultimate limit insignal detectability y. Itshould afford sufficient amplification to realize this ultimate limit and sufficient dynamic range toallow wide latitude inuseful signal intensities. 
 In Section 8, conclusion remarks are drawn. 2. Crab Nebula Pulsar Emission Based on Radio T elescope Measurements It is known that powerful celestial sources with small angular diameters as quasars, sources of hydroxyl radical (OH)-emission and pulsars, are characterized by huge values of e ﬀective temperature, the main preposition for a coherent radiation mechanism [ 1]. 
 STAGE #)# DECIMATION FILTER          .   2!$!2 $)')4!, 3)'.!, 02/#%33).'   Óx°Î£ &)'52%   #)# FILTER WITH DECIMATION  AFTER INTEGRATOR   &)'52%   &REQUENCY RESPONSE OF THIRD 
 Amplitude Characteristics. To predict the performance of an MTI system, the amplitude of the clutter signals with which a target must compete should be known. The amplitude of the clutter signals is dependent on the size of the resolution cell of the radar, the frequency of the radar, and the reflectivity of the clutter. 
 1715 -1727, October, 1960.  16. Ogg. 
 Note that the tail  fins are canted inward, thereby deflecting incident radar waves upward (away from  the radar) when seen from the side. This design greatly reduces the SR-71’s echo in a  narrow broadside sector of angles. The F-117. 
 22 of "Radar Technology," E. Brookner (ed.), A'rtech House,  Inc., Dedharn, Mass., 1977.  222INTRODUCTION TORADAR SYSTEMS 41.Metivier, R.L.:Broadband Klystrons forMultimegawatt Radars,Microwave J.,vol.14,pp.29-32, April,1971. 
 42”21’?J, 71°03’~V. aircraft ischecked atintervals against amap bythe identification of radar landmarks along theroute. The characteristics ofthe radar system must bekept inmind when flights are planned. 
 4.2) isthe total solid angle scanned inaparticular case, mthe solid angle included inthebeam, and 2’thetotal scanning time, itisnecessary toapply the restrictions discussed inthe previous section which require that N..Q2RQN9”–T=—Uv, Uc(2) Onthe other hand the number ofpulse packets inthe volume scanned is(Q/u) (2R/cT). Hence the number ofseparate volume elements examined persecond is (3) Since thepulse duration 7and thebandwidth @oftheradar receiver are ordinarily related approximately by@=1/7, itcan also bestated that the rate atwhich elements ofinformation are collected isofthe order ofmagnitude ofthe bandwidth (B. This conclusion, which has been approached byaroundabout way, isfamiliar tothecommunication engineer, whether heisconcerned with voice, facsimile, ortelevision transmission. 
 1.:DoublyDispersive Frequency Scanning Antenna, MicrowQl'e J.,vol.6,pp.76-80,July. 1963. 68.Loughren. 
 3CHMIDT ORTHOGONALIZATION  OR A (OUSEHOLDER 4RANSFORMATION 4HE ADAPTIVE WEIGHTS ARE THEN APPLIED TO THE RECEIVED SIGNALS AND BEAMFORMED TO GENERATE THREE SUM CHANNEL DETEC 
 One alternative the designer has  available is the use of multiple pulse-repetition frequencies for achieving the desired MTI filter  characteristics, as described next.  4.3 MULTIPLE, OR STAGGERED, PULSE REPETITION FREQUENC~S~, 17-22'8 1.82  The use of more than one pulse repetition frequency offers additional flexibility in the design of  MTI doppler filters. It not only reduces the effect of the blind speeds [Eq. 
 There are two additional drawbacks to the original configuration. Folding the spectrum around feedthrough folds the receiver noise as well, resulting in a 3 dB higher noise level (hence a 3 dB loss in sensitivity).5 The other problem stems from the fact that main-lobe clutter is the dominant signal in the doppler spectrum. Clutter harmonics can be misclassified as targets and must there- fore be avoided, thus limiting the usable range of target dopplers. 
 SURED FOR MANY GROUND 
  
 Thomas. H. W .. 
 Two other  ships, the destroyers USS San Francisco and USS Santa Fe, could not gain radar con - tact, but they did detect the splashes made by shells hitting the water. Nothing was  ever found. When U.S. 
 WHILE 
 The feed (in conjunction with the reflector) must also satisfy the antenna  polarization requirements and handle required peak and average power levels under  all operational environments. Other feed design considerations include the operating  bandwidth and the potential implementation of any additional modes/patterns, e.g.,  difference or squinted beams. For single-feed radar reflector antennas such as those depicted in Figures 12.25,  mechanical scanning is generally achieved via a gimbal (a precision mechanical point - ing system). 
 PARAMETER 3 
 A circulator is  used on the output port to protect the 100 W devices from antenna-generated reflections,  and control circuitry has been included to switch off modules in the event of cooling-   system failure. A 14:1 high-power replicated combiner built by using a combination of  reactive and resistive power-combining techniques in air-dielectric stripline, is employed  to sum the module outputs to the 25 kW level. REFERENCES  1. 
 The straps Sconsist ofrings which are connected only toalternate segments. The connections are made insuch away that one setofalternate segments isconnected byastrap atone end of theanode, and theother setofsegments isconnected byacorrespondhg strap atthe other end ofthe anode. Magnetrons may beeither single- ordouble- (oreven quadruple-) strapped, meaning they have either one ortwo (orfour) straps ateach end oftheanode. 
 16.11.—Block diagram ofdelay-line circuits, pulse-repetition period hastomatch thedelay time ofthesupersonic line with great accuracy. The velocity ofsound inmercury varies with the temperature byabout one part in3000 per degree centigrade, sothat temperature variations will cause the delay time todrift. This can be compensated forbyproviding atrigger generator whose PRF isaltered totake account ofchanges inthedelay time. 
 TEROMETERS v )%%% 4RANS  VOL '% 
 Nickel, “Sub-array configurations for digital beamforming with low sidelobes and adap - tive interferences suppression,” Proc. IEEE 1995 Int. Radar Conf ., Alexandria (VA), USA,  May 8–11, 1995, pp. 
 It is possible, however, to provide  a switch to disconnect the noncoherent MTI operation and revert to normal radar whenever  sufficient clutter echoes are not present. If the radar is stationary, a map of the clutter might be  stored in a digital memory and used to determine when to switch in or out the noncoherent  MTI.  The improvement factor of a noncoherent MTI will not, in general, be as good as can be  obtained with a coherent MTI that employs a reference oscillator (coho). 
 Syst. 2013 ,49, 468–488. [ CrossRef ] 17. 
 IEEE, vol.  56, p. 2098, November, 1968. 
 325–340, 1987. 60. D. 
 VIA. It was initially conceived in 1943, together with the interim Mk. VI and VIA solutions. 
 McCarthy, J. Wilson, and T. T. 
 Carter, J.-L. Margot, and N. J. 
   NO    PP n  3EPTEMBER   2 % :IEMER  4 ,EWIS  AND , 'UTHRIE  h$EGRADATION ANALYSIS OF PULSE DOPPLER RADARS DUE TO SIG 
 Ê " - 
 The running sum phase would steadily increase on every clock  edge, becoming 000 (0o), 001 (45o), …, 110 (270o), and 111 (315o). On the next clock  edge, the phase should be represented by 1000 for 360o. However, we are only pro - vided a 3-bit adder, so the MSB is simply lost, leaving us with a phase code of 000  (0o), which is the same as 360o. 
 Li, X.; Bond, E.J.; van Veen, B.D. An overview of ultra-band microwave imaging via space-time beamforming for early-stage breast-cancer detection. IEEE Antennas Propag. 
 PPM and PWM. The pulse-position and pulse-width values are based on the assumption of natural sampling,43 as is normally the case. In natural sampling, the deviation of the pulse edge is determined by the amplitude of the modulating signal at the time of occurrence of the pulse edge. 
 MOTION EFFECT  RESPECTIVELY %FFECT OF 3LANT 2ANGE ON $OPPLER /FFSET  4HE ANTENNA BORESIGHT VELOCITY  6" IS  THE GROUND 
 IRE T,vr~~s.,  vol. AP-6. pp. 
 This makes  triggering much easier. A Vector  Signal Analyzer (VSA), or a  spectrum analyzer in zero -span, can display amplitude v ersus  time. Th is is the equivalent of using a  RF detector. 
 The qualitative effects of target glint may be assessed from  this model. The relative amplitude of the two scatterers is assumed to be (1, and tlie relative  phase difference is a. Differences in phase might be due to differences in range or to ret'tccting  properties. 
 TO 
 MICRON PRODUCTION TRANSISTOR FEATURE SIZES  AND THE SMALLER FEATURE SIZES ALLOW FOR A COMPENSATED INCREASE IN HIGHER FREQUENCY OPERATION THAT IS  IT CAN EXHIBIT USABLE GAIN INTO 3 BAND )N PARTICU 
 SION FOR R  BECOMES   SPQ LF   02 0' RR T2 S I N    WHERE R2 IS THE SHORT 
 32. Appleton, E. V., arid M. 
 of the IEEE AP -S Int. Symp. & URSI R a- dio Science Meeting, San Jose, pp. 
 MER SPECKLE WILL EXHIBIT MORE PRONOUNCED BRIGHTNESS VARIATIONS  THAN THAT FROM SPOT  OR BARRAGE JAMMING  BECAUSE FEWER NOISE SAMPLES ARE ADDED NONCOHERENTLY  THEREBY REDUCING THE SMOOTHING EFFECT OF MULTIPLE LOOKS u 2EPEATER JAMMING  4HE ENEMY MAY UTILIZE THE TRANSMITTING RADAR TO SEND OUT A  SIGNAL WITHIN THE BAND OF THE 3!2 TO CONFUSE THE 3!2 SYSTEM RECEIVER 4HE JAMMING SIGNAL CAUSES THE 3!2 TO RECEIVE AND PROCESS ERRONEOUS INFORMATION THAT RESULTS IN SEVERE DEGRADATIONS IN THE 3!2 IMAGES ANDOR FORMATION OF THE IMAGE OF NONEXISTENT TARGETS ! DECEPTION JAMMING COULD BE COMPOSED OF MANIPULATED REPLICAS OF THE TRANSMITTED RADAR SIGNALS VIA $2&- )N (YBERG  THE POSSIBILITY OF PREVENTING 3!2  MAPPING THROUGH COHERENT $2&- JAMMING HAS BEEN INVESTIGATED ! SOFTWARE MODEL HAS BEEN DEVELOPED AND VERIFIED IN SEVERAL FLIGHT TRIALS IN THE CASE OF A GROUND 
 A common assumption in the design of many CF ARs is that the probability density  function of the background noise amplitude is known (usually taken to be gaussian) except for  a scale factor. Clutter, however, is often nonhomogeneous and thus nonstationary, as well as  being of unknown probability density function in some cases. With such uncertainty in the  background, a nonparametric method of detection must be used.75•78-:82 (A nonparametric  detector, also called a distribution-free detector, in its most general Corm does not require prior  knowledge of the probability density function of the noise or the signal.39) A nonparametric  detector permits a constant false-alarm rate to be achieved for background noise that might be  described by very broad classes of probabiJity density functions. 
       
 The system generates a linear FM (chirp) pulse waveform  for transmission by a traveling wave tube amplifier. The  2-kilowatt amplifier used on Seasat and GEOS-3 gave  evidence of not being able to support more than a few  thousand hours of operation. Therefore, an existing  20-watt amplifier, space qualified and in production for  the Landsat program, was selected for GEOSAT. 
 Thus the total area of  ambiguity, or uncertainty, is the same no matter how (z(TR, fd) I* is distributed over the TR, fd  plane, as illustrated by the sandbox analogy mentioned earlier in this section. The reader is  advised not to be distracted by trying to understand why this function is described by the  ambiguous use of the term "ambiguity."  11.5 PULSE COMPRESSION  Pulse compression allows a radar to utilize a long pulse to achieve large radiated energy, but  simultaneously to obtain the range resolution of a short pulse. It accomplishes this by employ-  ing frequency or phase modulation to widen the signal bandwidth. 
 BASED MEASUREMENTS &URTHERMORE  OTHER INFERENCES FROM THE . £°Ón  2!$!2 (!.$"//+  POLARIMETRIC MEASUREMENTS ALLOW ONE TO ESTIMATE THE PARAMETERS  OF THE GAMMA FUNC 
 Óx°Îä  2!$!2 (!.$"//+  &)'52%   &REQUENCY RESPONSE OF SINGLE 
 J. Condley, “The potential vulnerability to increased background noise of synthetic aper - ture radar in the maritime environment,” IEE Colloquium on Synthetic Aperture Radar ,  November 29, 1989, pp. 10/1–10/5. 
 AGES ARE ON THE ORDER OF VOLTS RATHER THAN KILOVOLTS TO AVOID THE NEED FOR LARGE SPAC 
 However, range predictions for distributed targets are sometimes wanted. The moon, for example, is a distributed target if the radar beamwidth is com- parable to or less than 0.5° or if the pulse length is less than about 11.6 ms. A rainstorm is another example of a distributed target. 
   PP n    * "LASS  h4HE MULTI 
 The  reaction time for the reconnaissance of the operational environment may be less  than 10 s, though dangerous emitters and alert functions call for tighter constraints.  Required sensitivity ranges from –55 dBm to better than –80 dBm. ELINT systems  are similar to ESM, but may not require 100% probability of intercept. 
 98 with the conical scan produces the Palmer scan, the cycloidal motion of thebeam which results when aconical scanner slowly traverses thehori- zon. The region ofsearch isahorizontal rectangle with semicircular ends. Palmer scan was used toaccomplish aneasy transition from the search function tothe gunlaying function ofafire-control radar. 
 This requires know - ing the contours of constant doppler shift (isodops) on the scattering surface. These  contours must be established for each particular geometric arrangement. A simple  example is presented here: horizontal motion over a plane earth. 
 Beach, C. L. Hindman, B. 
 COUNTERMEASURE FEATURE  BECAUSE IT PERMITS THE NULLS TO BE DEEPER THAN THE OPTIMUM CHOICE OF FOUR 
 Geosci. Remote Sens. 2017 ,55, 6390–6401. 
 LIKE STRUCTURES ON RELATIVELY LEVEL GROUND   HD2 (G COSQSQ    4HE INTERSECTION OF THE CONSTANT 
 EVER THE BISTATIC ANGLE IS GREATER THAN THE ESTIMATED  
 Despite many years of surveying, nothing has been  found apart from a small area of mud brick pavement. A number of radar sections had  been measured over this area previously, and in view of the magnetometry results, the  radar profiles were reexamined. The sections have been measured on 25 meter centers,  so it was purely by chance that one radar survey line went straight down the flight of  steps (excavated) seen in Figure 21.30 with the radar image in Figure 21.31.FIGURE 21.30  Temple steps ( Courtesy IEE ) FIGURE 21.31  Radar section along the flight of steps  (Courtesy IEE ) ch21.indd   36 12/17/07   2:51:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 PL PL 
 TO 
 Minhui, and H. Wen, “SAR activities in P.R. China,” in Proceedings , 6th European  Conference on Synthetic Aperture Radar , Dresden, Germany, VDE Verlag, 2006. 
 Sclicff. 13. t 1.. 
 Most of the data points are in the region 5° < P < 30° where -2 dB > vBlvM > -12 dB. Glint Reduction in the Bistatic RCS Region. A second effect can occur in the bistatic region. 
 (Afrer Ilours  and B~rlage.~~)  wi = weight at the ith tap.) A large number of delay lines are seen to be required of a  nonrecursive canceler if highly-shaped filter responses are desired. It has been ~uggested,'~  however, that even with only a five-pulse canceler, a five-pulse Chebyshev design provides  significantly wider bandwidth 'than the-five-pulse " optimum " design. To achieve the wider  band the Chebyshev design has a lower improvement factor (since it is not " optimum "), but in  many cases the trade is worthwhile especially if the clutter spectrum is narrow. 
 Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 
 TIME VARIATION OF THE FREE ELECTRON DENSITY DISTRIBUTION ! USEFUL SIMPLIFICATION IS TO REGARD THE LARGE 
 BAND LINEAR ARRAYS OF 6,0! ANTENNAS ARRAYS ORIENTED AT n TO EACH OTHER CONTIGUOUS  
   
 W. Cohen and C. M. 
 23.13  Measurement Accuracy  .....................................  23.15  Processor Implementations  ................................  23.17  23.5 Operational App lications  ......................................... 
 3, pp. 1171–1173, 2000. 35. 
 In Fig. 24.9 it is seen that the F2 critical is 6.5 MHz in the daytime and 4 MHz at night for summer. Figure 24.10 gives similar data but for winter, where the day and night comparison is from 8.4 MHz to 3.5 MHz. 
 ANGLE EQUATIONS 0LOTS OF BISTATIC CLUTTER DATA USE A SEPARATE AND QUITE ARCANE COORDINATE SYSTEM  WHICH IS DEFINED IN 3ECTION  'EOMETRY IS A PRINCIPAL FACTOR DISTINGUISHING BISTATIC FROM MONOSTATIC RADAR OPERA 
 Four ormore display con- soles, each with afull complement ofindicators, can beoperated inde- pendently and atthesame time from asingle radar. The fundamental principle oftheV-beam radar istoreduce theobser- vation ofelevation angle toadouble observation ofazimuth angle. The ...—.— - - —— -..--, f-u-. 
 OFFS  )T IS EASY TO SHOW THAT THESE RESOLUTION AND COVERAGE  OPTIONS ARE CONSISTENT WITH THE PRINCIPLES THAT GOVERN RANGE AND AZIMUTH AMBIGUITIES 4HE FUNDAMENTAL RULE IS THAT THE IMAGE SPACE ILLUMINATED BY THE ANTENNA  MUST BE hUNDERSPREADv IF AMBIGUITIES ARE TO BE AVOIDED  4HE UNDERSPREAD CONDITION IS THAT   4"2$OP     o  !LTERNATIVELY KNOWN AS 3POT3!2.   30!#% 
 LATE 
 Bothradarbandshavetobejammed simultaneously iftargetlocation istobedenied.. OTHER RADAR TOPICS 549  111 general, higher-frequency radars ~rsually are less vunerable to jamming than are iower-  freqi~ency radars. Orie reasorl is that the barldwidtli over which the higher-frequency radar can  operate is greater, thus causing tlie jarnmer to spread its available power over a greater  llurntwr of megallertz. 
 DOPPLER COVERAGE ! TYPICAL PROCESSING BLOCK DIAGRAM IS GIVEN IN &IGURE  %ACH 02& PROCESSING  INTERVAL IS DIFFERENT  BUT THEY AVERAGE OUT TO AN OPTIMUM  AS SHOWN LATER IN &IGURE  "OTH MAIN AND GUARD CHANNEL PROCESSING IS REQUIRED TO REJECT FALSE TARGETS  3OME  34!0 PROCESSING MAY HAVE BEEN PERFORMED BEFORE THIS PROCESS  BUT TRADITIONAL SIDE 
 Frequency shifting is accomplished by spectrally convolving this signal with  the complex –75 MHz LO tone shown in line 4, producing the frequency-shifted sig - nal on line 5. The latter signal is spectrally multiplied by the filter response shown on  line 6 to remove the copies of the negative-frequency signal component, producing  the complex baseband signal shown on line 7. This signal, which now has a two-sided  bandwidth and Nyquist frequency of 40 MHz, is spectrally convolved in line 8 with  impulses at the spectral origin and at 50 MHz to effectively decimate the signal by a  factor of two.3 The final baseband signal on line 9 has a sample rate of 50 MHz. 
 0.424x10’ 150 1,5 80 160 1.5 ment ofthereal target, which extends over anelevation range from zero toitsactual height and whose illumination varies with elevation, bya target atan“effective height” determined experimentally. Adifferent attempt hasbeen made byM,Katzin,’ who computes the 10.J.Baltzer, V.A.Counter, W.M.Fairbank, tf”.0,Gordy, E.L.Hudspeth, “Overwater Observations at.Yand,’5’Frequencies,” RLReport ATO.401, June 26. 1943, 2Navy Report RA3A213.\.. 
 representing the sea  Without the least vestige of land;  And the crew were much pleased when they found it to be  A map they could all understand!  . XI. ELECTRONIC NAVIGATION  E HAVE NOWADAYS A RESPECTABLE CHOICE OF TRUE  W radar navigational aids, apart from those such as  the QM and Console, which are not within the strict  scope of pulse-radar navigation. 
 Although they add complexity, cost, and possibly weight to the antenna, reduction of main-beam width and control of coverage and scan are valuable and worthwhile ECCM fea- tures of all radars. If an air defense radar operates in a severe ECM environment, the detection range can be degraded because of jamming entering the sidelobes. On transmit, the energy radiated into spatial regions outside of the main beam is subject to being received by enemy RWRs or ARMs. 
 ING PROCESS SINCE THE TARGET BEARING DOES NOT VARY FROM PULSE TO PULSE 4HEREFORE  AMPLITUDE COMPARISON MONOPULSE ANTENNAS OR MULTIPLE BASE INTERFEROMETRIC PHASE COMPARISON  SYSTEMS ARE OFTEN USED IN ORDER TO WARRANT BOTH  SPATIAL COVERAGE AND PULSE 
 In Carrano’s work, the inverse range-Doppler algorithm (RDA) is applied to generate the unaffected SAR signal. However, it cannot actually simulate the observation geometry of SAR system, thus it is not suitable to reconstruct the SAR raw data for the sliding spotlight SAR system. The former research builds the foundation of our work. 
 Sensors 2019 ,19, 490 The subaperture imaging methods for WASAR imaging assume that the scattering of the targets are not relevant to the aspect angle in a narrow angle. Then, a traditional imaging method can be implemented in subaperture image focusing. CS has been introduced into SAR imaging [ 4]. 
 From the point ofview oftheradar designer, targets over thehorizon might aswell beregarded astotally inaccessible under ‘1standard” conditions ofpropagation. D,stanceinmales FIG,2.14.—Coverage diagram for2600 Me/see, transmitter height 120ft.Solid curve for totally reflecting earth. Dotted curve fornonreflecting earth.. 
 The MIMO principle of operation is to transmit and receive the radar signal alternately from various appropriately located elements. This strategy allows to synthesize an arbitrary antenna array, using a relatively small number of physical elements, thus limiting the complexity and cost of the whole system with respect to standard ESA [ 12]. Despite the innovations introduced by the MIMO strategy, the prototypes developed so far [ 10,11] still seem to suffer from major disadvantages in terms of production cost and ease of installation. 
 5, No. 20, pp. 416- 198, Oct. 
 LIMITED CONDITION /VER A NOMINALLY LEVEL FLAT  SURFACE  THE ALTIMETERS SHORT PULSE  A  REFLECTS FIRST FROM AN AREA THAT MAY BE  MUCH SMALLER THAN THE FOOTPRINT ILLUMINATED BY THE ANTENNA PATTERN B          !   
 WIDTH 2 IS THE RANGE TO THE CLUTTER METERS  AND C IS THE SPEED OF PROPAGATION )T SHOULD BE NOTED THAT FOR LAND CLUTTER  R  CAN VARY CONSIDERABLY FROM ONE RESOLU 
 One method of  determining !'he relative phase relationship between the two channels is to apply the outputs to  a synchronous two-phase motor." The direction of motor rotation is an indication of the  direction of the target motion.  Electronic methods may be used instead of a synchronous motor to sense the relative  phase of the two channels. One application of this technique has been described for a rate-of-  climb meter for vertical take-off aircraft to determine the velocity of the aircraft with respect to  the ground during take-off and landing.'' It has also been applied to the detection of moving  targets in the presence of heavy foliage," as discussed in Sec. 
 tothoseradarsoperating atVHForlower.Themagnitude ofcosmicnoisedepends upontheportion ofthecelestial sphereinwhichtheantenna points.Itisamaximum when lookingtowardthecenterofourowngalaxy,anditisaminimum 'vhenobserving alongthe poleaboutwhichthegalaxyrevolves. Aplotofthemaximum andminimum cosmic-noise brightlless temperature asafunction offrequency isshownbythedashedcurvesofFig.12.11. Thebrightness temperature ofanextended sourceofradiation isthetemperature ofablack­ bodywhichyieldsthesamenoisepoweratthereceiver. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.40  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 The explanation given above applies to an antenna operating at a single (CW) fre - quency and describes how the beam moves as this frequency is changed. However, most radars are pulsed and radiate over a band of frequencies. 
 NOISE RATIO 3.2       THEN THE SMALLER THE PHYSICAL ANTENNA  THE FINER THE CROSSRANGE RESOLUTION  INDEPENDENT  OF RANGE !S THE PHYSICAL ANTENNA MOVES ALONG THE SYNTHETIC APERTURE  THE RETURN FROM A  POINT TARGET AT A PARTICULAR RANGE WILL EXHIBIT A QUADRATIC PHASE BEHAVIOR IE  PHASE VARIES AS THE SQUARE OF THE TIME REFERENCED TO THE CLOSEST APPROACH  THAT IS UNIQUE TO THE TARGETS LOCATION ON THE GROUND   3OME STRIPMAP 3!2S USE A FILTERING APPROACH  TO TAKE ADVANTAGE OF THIS PHENOMENON )N FACT  FOR THE ECHO FROM A POINT TARGET IN  THE SCENE  A CLOSE ANALOGY EXISTS BETWEEN ITS QUADRATIC PHASE VARIATION DURING A SINGLE PULSE FROM A LINEAR &- ;,&-= PULSE ECHO  AND ITS QUADRATIC PHASE VARIATION OVER MANY PULSES DUE TO PLATFORM MOTION 3TIMSON   P   /THER STRIPMAP 3!2S DIVIDE  THE STRIP INTO  SUBPATCHES AND USE SPOTLIGHT 
 Therecirculating delay-line integrator, range-gated hilabank,and storage-tube integrator allhavebeenusedinthepastfortheelectronic pro&ssing ofun­ focusedSAR.1Theopticalprocessor wasusedforfocusedsystems. Digitalprocessing isalso practical andhastheadvantage ofreal-time operation ascompared withopticalprocessing. Thedigitalprocessor hasIandQchannels withahigh-speed A/Dconvertor ineachchannel. 
 Printed in the United States of America. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a data base or retrieval system, without the prior written permission of the publisher. Chapters 8, 13, and 24 were prepared by the contributors as part of their employment by the United States government and are not subject to copyright. 
 LOW NOISE FREQUENCY  REFERENCES ARE REQUIRED TO IMPROVE SUBCLUTTER VISIBILITY ON LOW 2#3 TARGETS EVEN USING 34!0 2ANGE GATING DRAMATICALLY IMPROVES SIDELOBE CLUTTER REJECTION  WHICH ALLOWS OPERATION AT LOWER OWNSHIP ALTITUDES 0RINCIPAL LIMITATIONS OF 2'(02& CLOSING TARGET DETECTION PERFORMANCE ARE ECLIPSING A RADAR RETURN WHEN THE RECEIVER IS OFF DURING THE TRANSMITTED PULSE  AND RANGE GATE STRADDLE LOSSES THE RANGE GATE SAMPLING TIME MISSES THE PEAK OF THE RADAR RETURN   &IGURE  SHOWS 40I WITH ECLIPSING AND STRADDLE LOSSES  NEAR MAXIMUM RANGE FOR A HIGH PERFORMANCE 2'(02& 4HIS MODE IS OPTIMIZED FOR LOW CROSS SECTION TARGETS OUT TO JUST BEYOND  KM MAXIMUM RANGE 4HE PARTICULAR EXAMPLE HAS OVERLAPPING RANGE GATES TO MINIMIZE STRADDLE LOSS AND TWO 02&S TO ALLOW AT LEAST ONE CLEAR 02& NEAR MAXIMUM RANGE 4HE 02&S ARE  K(Z AND  K(Z $UTY RATIO IS  WITH  D" REQUIRED DETECTION 3.2 !VERAGED OVER ALL POSSIBLE TARGET POSI 
 Hoft, “Solid-state transmit/receive module for the PA VE PAWS phased array radar,” Microwave  Journal , pp. 33–35, October 1978. 34. 
 This type of  antenna is similar in many respects to the torus antenna described below.  Parabolic Torus. Wide scan angles in ene dimension can be obtained with a parabolic-torus  config~ration,~'-~~ the principle of which is shown in Fig. 
 OBSERVING MISSIONS TO RELY ON THE PURELY PASSIVE GRAVITY 
 As a result, Navy radars must have significantly higher clutter rejection  capabilities and larger dynamic ranges than existing radar systems. Recently, digital  beamforming has been proposed for radar systems that must detect small RCS targets  in severe clutter environments.99 The dynamic range determines the range of power levels that can be processed  in the linear operating region of the receiver. The radar system must be able to pro - cess high power clutter returns without saturating the receiver. 
 WAVELENGTH DIMENSION OF THE FREQUENCY GIVEN ON THE LOWER SCALE 4HE CURVE MARKED n  IS THE 2#3 OF THE OBLONG 
 !NGLE  2ADAR  ,AND  #LUTTER  -EASUREMENTS  AND  %MPIRICAL  -ODELS    .ORWICH  .9 7ILLIAM !NDREW 0UBLISHING  &)'52%   %XAMPLE OF COVERAGE OBTAINED WITH A TWO 
 BOARD SYS TEMS  SUCH AS THE INER 
 However, analysis of Shuttle Imaging Radar (SIR) data  permits some estimates to be made of the variability to be expected for different  sizes of illuminated footprint. The general characteristics of radar backscatter over the range of angles of inci - dence have been known for decades. Figure 16.22 shows these. 
 Figure 1. Typical main pulse time-frequency structure of Crab Nebula’s pulsar emission registered in Goldstone-Apple Valley radio telescope [ 12]. Based on characteristics of the main pulse deﬁned in [ 5,11,12], it is worth noting that the main pulse consists of several microbursts, the time dimension of which is ≤1μs long at 8−10 GHz, with a bandwidth≥2 GHz. 
 ofastrong field, electrons arequickly removed byattachment tomolecules. Molecular ions have somuch inertia that atthe frequencies involved they cause negligible attenuation. Water vapor isthe constituent usually introduced tohurry theelectron cleanup. 
 If a model learns the most of detail and noise of training data, it cannot get good performance in new data, then the over-ﬁtting happens. Some useless information such as noise and random ﬂuctuations have been learned while training as parts of the models. Then the models cannot have good generalize ability in new data. 
 °Ê9i>Ã 2AYTHEON #OMPANY È°£Ê / 
 Good slow- moving target rejection. Measures radial velocity. Velocity-only detection can improve detection range.Disadvantages Low doppler visibility due to multiple blind speeds. 
 SURFACE HEIGHT 33(  )N RESPONSE  ALGO 
   
 For devices that are designed to operate for long pulses or CW, an  increase in the average power capability of the transistor can be achieved by dividing  the active area of a transistor into small, thermally isolated cell areas. Since the overall thermal time constant for a typical power transistor die itself may  be on the order of 100–200 µs, the tradeoff between peak and average power versus  device size can be significant for solid-state radars using pulse compression with pulse  widths in the 10 to 1000 µs range. As an example, the thermal time constant of a silicon  die with a thickness of 5 mils is approximately 90 µs whereas a gallium arsenide die  with a thickness of 4 mils is approximately 170 µs. 
 M =  4&2    FALSE 
 BOUND TARGET      !VERAGE OF 43, POWER RATIO4!",%    #OMPARISON OF ,INEAR &- AND .ONLINEAR &- 7AVEFORM 0ERFORMANCE . 
 145–154, 1980. 125. R. 
 COMBINED OR CORPORATE 
 EQUIVALENT MELTED  SNOW "ATTAN GIVES A MORE COMPLETE TREATMENT OF THIS IMPORTANT TOPIC.   -%4%/2/,/')#!, 2!$!2   £°ÓÇ 7ILSON AND "RANDES GIVE A COMPREHENSIVE TREATMENT OF HOW RADAR AND RAIN 
 LENGTH TEN TIMES THE FULL 
 WATT INTERNALLY MATCHED POWER TRAN 
 The blurring in the cross-range direction is greatly removed in Figure 12d. As stated previously, the image quality of the proposed method results are superior to the original images, DCT and PGA results from a visual point of view. The entropies and IC values during iteration are represented in Figure 13. 
 Before the late 1960s, most clutter data was collected in bits and pieces from isolated experiments, often with poor or incomplete ground truth. (For reviews of the older literature see, for example, Long,1 Skolnik,2 or Nathanson.3) Neverthe- less, though much of the earlier clutter data was of limited scientific value, it did disclose some general trends, such as the tendency of clutter signal strength at low to intermediate grazing angles to increase with the grazing angle and with wind (or sea state) and generally to be greater for vertical polarization and in upwind-downwind directions. It is commonly noted that, when viewed on an A scope, the appearance of sea clutter depends strongly on the size of the resolution cell, or radar footprint. 
 23.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 23 Waveforms.  The effective radiated power (ERP) of broadcast transmitters  can vary  from a maximum of ~1 MW for TV transmitters to a minimum of ~10 W for cell-phone  tower transmitters. The former can yield equivalent monostatic detection ranges of air  targets of 100–150 km; the latter, 1–5 km, which is of the order of the cell-phone wave - form resolution, typically 2 km.2 Consequently when these low-powered transmitters  are evaluated for short-range ground or air target location.121 only doppler (and coarse  DOA) data are available, which severely restricts location capability, as outlined in  Section 23.6. 
 Ontheother hand, ifhigh-power oscillations are tobemaintained, aplate voltage at least ashigh asthis starting voltage (V.) must bemaintained atlarge currents. This calls either foravery low- impedance pulser orforahigh pulser voltage VOatzero load current. Consider the case illustrated in’Fig. 
 TER TO THE TARGET AND THE TARGET TO THE RECEIVER )N CONTRAST TO A MONOSTATIC RADAR  HOWEVER  PROPAGATION EFFECTS CAN BE SIGNIFICANTLY DIFFERENT OVER THE TWO  BISTATIC PATHS AND MUST  BE TREATED SEPARATELY -ULTIPATH IS THE PRIMARY EXAMPLE  WHERE THE TARGET CAN BE IN A MULTIPATH LOBE ON ONE PATH AND A MULTIPATH NULL ON THE OTHER  DEPENDING ON ANTENNA AND TARGET ALTITUDE AND TERRAIN CONDITIONS 7HEN A CORRELATION RECEIVER USES THE DEMODULATED DIRECT PATH 2& SIGNAL AS ITS REFER 
 The element density may be thinned  so as to taper the amplitude distribution effectively, and the spacing is such that no  coherent addition can occur to form grating lobes. A thinned aperture, where elements  have been removed randomly from a regular grid,54 is shown in Figure 13.12. The  gain is that due to the actual number of elements NGe(q ), but the beamwidth is that  FIGURE 13.12  (a) Thinned array with a 4000-element grid containing 900   elements. 
 Asingle 829 or3E29 tube atT2will satisfactorily drive two Eimac 304TH’s ortwo Western Electric 715B tubes; ei~her complement oftubes isadequate todeliver over 200 kwtotheload. Circuit constants given inFigs. 10.31 and 10.33 arerepresentative and have been used inapulser produced inlarge quanties. 
 U. Mel’nichuk and A. A. 
 SYSTEM BLOCK DIAGRAM  A  SEPARATE TRANSMITTER AND RECEIVER    CALIBRATION AND B   CALIBRATION OF THE RATIO OF RECEIVED TO TRANSMITTED POWER. 
 The performance achieved with various frequency-weighting functions is summarized in Table 10.8. With a change in parameter, the table also applies to time weighting (or weighting of the aperture distribution of an antenna). Pedestal height H is defined in all cases as the weighting-function amplitude at the band edge (f = ±B/2) when the function has been normalized to unit amplitude at the band center (f = O). 
 The complexity of transmitter amplifier chains often makes it dif- ficult to achieve the desired reliability. Solutions usually involve the use of re- dundant stages or a whole redundant chain, and many combinations of switch- ing are feasible. Careful analysis and restraint are usually necessary; otherwise, the complexity and cost of fault monitoring and automatic switch- ing very quickly grow out of bounds. 
 RANGE AIR SURVEILLANCE   0ULSE #HASING  )F THE TRANSMITTERS BEAM SCANNING  AND PULSE TRANSMISSION SCHED 
 FIRE ANTENNA )T CAN BE AN ELECTRONICALLY SCANNED PHASED ARRAY USING A SINGLE TRANSMIT 
 ICE   BEST ILLUSTRATED BY %ARTH 
 The PSD function of Rino spectrum is expressed as Pφ(κ)=r2 eλ2sec2(θ(κ))·CsL·a·b /bracketleftBig q0+/parenleftBig Aκ2x+Bκxκy+Cκ2y/parenrightBig/bracketrightBig(p+1)/2 (19) 191. Sensors 2019 ,19, 2161 where reis the classical electron radius, λis the signal wavelength. Both aand bare structural scaling factors of irregularities along and across the magnetic ﬁeld. 
 The frequency-scan  radar uses a linear-array antenna to scan a beam in one angular coordinate by changing the  frequency. The use of the frequency domain for electronic beam scanning normally pre­ cludes the use of the frequency domain for range resolution. That is, pulse compression and  frequency scan are often not compatible. 
 The sim- plest scatterometer uses a stationary CW radar. Such systems are not very flexible, but they are discussed here in some detail to illustrate calibration techniques that also apply to the more complex systems.SAMPLES AT R1 FIG. 12.11 Fading for successive pulses of a radar with ground target.PULSE LENGTH TRANSMITTEDPULSE SHAPE(NOT TO SCALE) TRANSMITTEDPULSE LENGTH . 
 Maximizing the response to FM yields a less exact ad- justment.MICROWAVESOURCETRANSMISSION CAVITY DETECTORDETECTOR PHASE SHIFTER AMPLIFIER SERVO . An obvious disadvantage of the transmission-cavity bridge is that the carrier is not suppressed in the microwave circuitry. Since the total input power is limited by fear of crystal damage and of exceeding the linear range in the mixing process, the intelligence signal power at a relatively low level is in competition with the thermal noise generated by the crystals. 
 How are we going to  relate this knowledge of the speed of radio waves to our  practical problem of locating, say, an aircraft in the  night skies or a ship in fog?  ‘Radar’ is a war-born word, coming out of the British  31  . 32 HOW RADAR WORKS  ‘radio-location,’ which not only was considered to be  insufficiently streamlined for the wonderful new tech-  nique, but was not expressive. Radar to-day is much  more than ‘location.’ So the word ‘ra-dar’ was coined  to describe ‘radio detection and ranging,’ though it  would be truly more descriptive if the phrase were  ‘radio direction-finding and ranging.’ :  Now radio waves travel at the same speed as light  waves, and, indeed, share many of the same properties. 
   3EPTEMBER   7 ' "ATH  , ! "IDDISON  3 & (AASE  AND % # 7ETZLAR  h&ALSE ALARM CONTROL IN AUTOMATED  RADAR SURVEILLANCE SYSTEMS v IN )%% )NT 2ADAR #ONF  ,ONDON    PP n  # % -UEHE  , #ARTLEDGE  7 ( $RURY  % - (OFSTETTER  - ,ABITT  0 " -C#ORISON  AND 6 *  3FERRINO  h.EW TECHNIQUES APPLIED TO AIR 
 NIQUES ARE USED TO OPTIMIZE THE RESOLUTION OF THE IMAGE AND WILL BE DISCUSSED LATER 4!",%  #HARACTERISTICS OF '02 3YSTEMS IN A 3OIL OF 2ELATIVE $IELECTRIC #ONSTANT OF  AND  ,OSS 4ANGENT OF  0ULSE $URATION IN NS #ENTER &REQUENCY IN -(Z 2ANGE IN -ETERS $EPTH 2ESOLUTION                                                  .   '2/5.$ 0%.%42!4).' 2!$!2   Ó£°x 5NPROCESSED '02 IMAGES OFTEN SHOW hBRIGHT SPOTSv CAUSED BY MULTIPLE INTER 
 Digital beamforming systems require a large number of channels with similar  coherence and synchronization requirements and tight phase and amplitude track - ing. The coherence requirement dictates the relative phase stability of LO and  A/D converter clock signals used for each receive channel. The time synchroniza - tion requirement means that A/D converter clock signals for each channel must  be aligned in time and decimation must be performed in phase for each channel. 
 DIMENSIONAL ADAPTIVE PROCESSING FOR JOINT CLUTTER AND JAMMER CANCELLATION  ADAPTIVITY AT THE SUBAR 
 38. Xiangjun, F. Viscosity (rigidity coe ﬃcient) of high concentration turbid water. 
 tracking of ballistic tnissiles (Cobra Dane), and airborne bomber radar (EAR).  There have been many developmental array radars built in the United States, including  ESAR. ZMAR, MAR, Typhon, Hapdar, ADAR, MERA, RASSR, and others. 
 TOR ANTENNA DESIGN 4HE ELEVATION BEAM SHAPE IS TAILORED USING A COMPUTER 
 An example of the use of these filter characteristics applied to  the design of a delay-line periodic filter is given in either of White's papers.2•12 Consider the  frequency-response characteristic of a three-pole Chebyshev low-pass filter having 0.5 dB  ripple in the passband (Fig. 4.14). The three different delay-line-filter frequency-response char­ acteristics shown in Fig. 
 In addition to radar and other sensor systems, electrical  engineering systems  include  communications,  control,  energy,  information,  industrial,  military, navigation, entertainment, medical, and others. These are what the practice of electrical engineering is allabout. Without them there would be little need for electrical engineers. 
 IMPLEMENTED PROPAGATION MODELS  HOWEVER  THE ASSUMPTION OF FREE SPACE NEED NO LONGER BE A LIMITING FACTOR /NE SUCH PROPAGATION MODEL  THE !DVANCED 0ROPAGATION -ODEL !0-  AND ITS GRAPHICAL USER INTERFACE PROGRAM  THE !DVANCED 2EFRACTIVE %FFECTS 0REDICTION 3YSTEM !2%03    ARE FEATURED HERE 7HILE THE FOCUS UPON !2%03  WITHIN THIS CHAPTER IS FOR THE UNDERSTANDING OF HOW IMPORTANT THE PROPAGATION FACTOR IS WITHIN THE RADAR EQUATION  !2%03 IS MUCH MORE THAN A PROPAGATION FACTOR TOOL !2%03 PROVIDES THE RADAR ENGINEER AND THE OPERATIONAL RADAR OPERATOR WITH AN EASY TO USE BUT EXTREMELY POWERFUL METHOD TO DEFINE THE NATURAL ATMOSPHERIC ENVIRONMENT USING DATA FROM A WIDE RANGE OF SOURCES TO MANAGE  CREATE  AND DEFINE VARIOUS ELEMENTS OF TER 
 Pencil bi.:ams arc  commonly used where it is necessary to measure continuously the angular position of a target  in both azimuth and elevation, as, for example, the target-tracking radar for the control of  weapons or missile guidance. The pencil beam may be generated with a metallic rdlector  surface shaped in the form of a paraboloid of revolution with the electromagnetic energy fed  from a point source placed at the focus.  Although a narrow beam can, if necessary, search a large sector or even a hemisphere, it is  not always desirable to do so. 
 The effective lengthofthesynthetic aperture canbelimitedbythestability ofthetransmitter orthe receIver. TheheartoftheSARistheprocessor whichmustprovidetheproperamplitude andphase weightstothestoredpulses,andsumthem!oobtaintheimageofthescene.Opticalprocessors anddigitalprocessors havebothbeenused. Angular motions inyaw,roll,andpitchoftheaircraftcarrying theradarwillcausethe realantenna beamtopointincorrectly. 
 Ricardi. L. J., and L. 
 N DEMD E E 
 An especially common multiple  beam design is the monopulse antenna in Figure 12.15 e, used for angle determination  on a single pulse, as the name implies. In this instance, the second beam is normally a  difference beam with its null at the peak of the first beam. FIGURE 12.15  Common reflector antenna types: ( a) paraboloid, ( b) parabolic cylinder, ( c) shaped,  (d) stacked beam, ( e) monopulse, and ( f) Cassegrain ch12.indd   16 12/17/07   2:31:21 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 $  PP n    & &EINDT  6 7ISMANN  7 !LPERS  AND 7 # +ELLER  h!IRBORNE MEASUREMENTS OF THE OCEAN RADAR  CROSS SECTION AT  '(Z AS A FUNCTION OF WIND SPEED v 2ADIO 3CI  VOL   PP n    , # 3CHROEDER  0 2 3CHAFFNER  * , -ITCHELL  AND 7 , *ONES  h!!&% 2!$3#!4  
 The receiver bandwidth, meanwhile, isreduced to about U,cps. The result isessentially ac-wsystem insofaraspower and sensitivity areconcerned, with abandwidth ofv,. Itcan seeasfaras the previous radar system, but itcannot seeasmuch inthe same time. 
 Dan P. Scholnik of the Naval  Research Laboratory, a doppler filter bank meeting the above constraints was designed.  The first filter, which has its peak located as close as possible to the left edge of the  constraint box is shown in Figure 2.59, with the abscissa normalized to the total avail - able doppler space.FIGURE 2.57  Average SCR improvement for the 68 dB Chebyshev filter bank shown  in Figure 2.55. 
 values of c.;  arc bctwect~ 10 arid 10 " m '13 , wl~icli correspond to a volume reflectivity of about  0.82 x 10 to 0.82 x 10 " ni - ' at S band (A = 10 cm). This is quite low as can be seen by  coniparisoti of the volume reflectivity for rain in Fig. 13.12. 
 This reduces the time required in searching for an uneclipsed PRF. Multiple-Target Tracking. Multiple-target tracking can be accomplished in several ways. 
 OFF BETWEEN PROPAGATION THROUGH 6ENUS VERY DENSE ATMOSPHERE FOR WHICH LONGER WAVELENGTHS WOULD BE BETTER  AND SYNTHETIC APERTURE RADAR SYSTEM CONSIDERATIONS FOR WHICH SHORTER WAVELENGTHS WOULD BE BETTER  0ROPAGATION SPEED IS RETARDED ALONG THE PATH LENGTH FROM AN OCEAN 
 Rec., 1975, pp. 408–411. 25. 
 WAVELENGTH SCALE OF THE OBSERVABLE PERTUR 
 TIONS THAT EXPRESS AN EXCESS OF HIGHER RETURNS  SUCH AS THE 7EIBULL AND + 
 (ILL "OOK #OMPANY     % "ROOKNER  h0HASED ARRAY RADARS v 3CI !M  VOL   PP n  &EBRUARY  ( 0 3TEYSKAL  h0HASED ARRAYS  SYMPOSIUM v IN  2!$#  2EPT  42 
 It has also been called  si11111lta11eo11s-phase-compariso11 radar, or phase-comparison monupulse. The latter term is the  one which will be used here.  In Fig. 
 55. Trunk, G. V.: Comparison of thc Collapsing Losses in Linear and Square-law Detectors, Proc. 
 88. “Bistatic radars hold promise for future systems,” Microwave Syst. News , pp. 
 lEEE Publ. 75 CHO 939-1 AES.  40. 
 Inf. Theory 2015 ,61, 2081–2100. [ CrossRef ] 21. 
 MANCE AND HAVE GENERALLY DISPLACED SCANNING AND LOBING TRACKING RADARS FOR MEETING THE INCREASING DEMANDS FOR HIGH PRECISION AND HIGH DATA RATE OF ANGLE INFORMATION ON EACH PULSE (OWEVER  SPECIAL RADAR TRACKING REQUIREMENTS MAY EXIST WHERE A PRACTICAL IMPLEMENTATION OF CONICAL SCAN OR LOBING TRACKING RADAR MAY MORE EFFECTIVELY PROVIDE ADEQUATE PERFORMANCE °{Ê - 
 TION  WHERE hHIGHERv IS hBETTERv (IGHER RESOLUTION ALWAYS IMPLIES WIDER BANDWIDTH IN BOTH RANGE AND AZIMUTH !ZIMUTH BANDWIDTH DERIVES FROM THE DOPPLER SIGNATURES SET UP BY THE MOTION OF THE RADAR WITH RESPECT TO THE ILLUMINATED FIELD 2ESOLUTION BY ITSELF IS NOT SUFFICIENT TO DETERMINE THE IMAGE QUALITY OF IMPORTANCE TO MOST APPLICATIONS     4HE FIELD OF SPACE 
 contributed materials; X.H. and K.J. wrote the paper; G.D. 
 Sensors 2019 ,19, 3073 post-construction, the external load can be considered as constant and the underground deformation increases with time, so the rheological deformation plays a dominant impact role. In the theory of rheology, the rheological model is a kind of mechanical model (composed of spring, dashpot, and slide rod) that represents the rheological characteristics of rocks and soil and describes the dynamic temporal evolution process. The most widely used rheological models can be divided into linear models and non-linear models. 
 RADAR ANTENNAS 231 valueoftheaperture distribution isequaltoAoandifthephasedistribution acrosstheaperture isconstant, theantenna patternascomputed fromEq.(7.10)is E(¢)=Ao(:2expJ(21£lsin¢)dz =A~_~i!1_1~~~~Jl~~~J =Aoa[sin1£(a/J)sin¢J (1£/J)sin¢ 1£(a/J)sin¢ Normalizing tomakeE(O)=IresultsinAo=I/a;therefore E(¢)=sin[1£(ajA)sin¢] n(a/J)sin¢(7.15) (7.16) Thispattern, whichisoftheform(sinx)/x,isshownbythesolidcurveinFig.7.3.The intensity ofthefirstsidelobe is13.2dBbelowthatofthepeak.Theangular distance between thenullsadjacent tothepeakis2A/arad,andthebeamwidth asmeasured between thehalf­ powerpointsisO.88J/arad,or5lA/adeg.ThevoltagepatternofEq.(7.16)ispositive overthe entiremainlobe,butchanges signinpassing through thefirstzero,returning toapositive valueinpassing through thesecond zero,andsoon.Theodd-numbered sidelobes are therefore outofphasewiththemainlobe,andtheeven-numbered onesareinphase.Also showninFig.7.3istheradiation patternforthecosineaperture distribution. nzA(z)=cos­a..,:,. -41T-3,.,.-21Tc 0....a -15"0a L (1) >....a -20(1) L N- -a -25'-l.l -1T 0 1T 1T(a/A) sin¢21T 3rT Figure7.3Thesolidcurveistheantenna radiation patternproduced byauniformaperture distribution; thedashedcurverepresents theantenna radiation patternofanaperture distribution proportional tothe cosinefunction.. 
 Itnow remained only toestimate the power required. This could bedone either onthe basis ofexperience with similar systems orby calculations ofthesort outlined inChap. 2. 
 2.26  Available Power, Gain , and Loss  ........................  2.26  Noise Temperature  ............................................  2.27 The Referral Concept  ........................................ 
 This transit time must be small compared to the period of the RF  signal to be amplified. To minimize the undesired transit-time effects, the complete RF  input and output circuit and the electrical interaction system can be placed within the  vacuum envelope. Such a grid-controlled tube is called a Coaxitron .42 In one embodi - ment of the Coaxitron, the electron-interaction structure consisted of a cylindrical  array of 48 essentially independent grounded-grid unit triodes. 
 However,  this involves a certain amount of adaptation of the radar under test, which may be  considered inappropriate. The potential move at 3 GHz to pulse compressed radar offers additional chal - lenges in the design of a universal simulator, as the system described is based on  testing noncoherent pulsed radars. Systems based on digital RF memory may have to  be devised, storing waveforms that can be subsequently processed. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 17 .12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 Through appropriate range-doppler processing, returns from each intersection  cell may be distinguished. 
 In this cases SAR autofocus algorithms [ 8–12] are used to solve the problem in a blind mode. SAR autofocusing algorithms are categorized into three types: sub-aperture-based algorithms, prominent point-based algorithm, and metric-based autofocus. Most of the traditional autofocus algorithms assume there are strong scatters in the scene. 
 The output of the radar system, therefore, is the weighted average of p over a domain determined by the limits of integration. If the ambiguity function is localized at some point and is essentially zero at all other points, the output will be a good representation of the radar reflectivity at that point. Otherwise, the estimate of the reflectivity at a given point will be the weighted average given by Eq. 
 K. G. Schroeder, “Near optimum beam patterns for phase monopulse arrays,” Microwaves ,   pp. 
 THE 
 The modulating anode provides the means to  pulse the electron beam on and off. The RF cavities  are the microwave equivalent of  a resonant circuit. Electrons are not intentionally collected at the anode (as they are  in grid-controlled tubes and crossed-field tubes), but in the collector,  shown at the  right-hand side of the illustration, after the electron beam has given up its RF energy  at the output cavity. 
 On most  equipments, therefore, we have to choose a setting  where we get sufficiently strong echoes received back  from our distant object without the display being  cluttered up in a mass of grass. Unless an echo is strong enough to cause a blip on our CRT deep enough to show above the grass layer we shall miss it.  Radar transmitters, naturally, are complicated pieces of apparatus, because they must be designed to send out a pulse of tremendous energy thousands of times a ‘second, and must then cut clean off, so far as outgoing  oscillation is concerned, so that the pulse can travel out  into space and, if it hits any distant object, have ample opportunity to be cleanly reflected home again before the next pulse goes out; and this process must be con- tinued hundreds, perhaps thousands, of times a second. 
 designed the experiments and produced the results; X.X. and L.C. analyzed the precipitation data; X.X., Z.Y., and Z.S. 
 BOARD CUES TO INCREASE  THE PROBABILITY OF ACQUIRING A TARGET USING #UED 3EARCH ! #UED 3EARCH MODE ADJUSTS  THE SEARCH VOLUME AND WAVEFORM SELECTION ACCORDING TO THE ACCURACY OF THE CUES  PARAMETERS 2ADARS WITH ELECTRONICALLY SCANNED ARRAY %3!  ANTENNAS CAN INTERLEAVE OTHER FUNC 
 Angular motions in yaw, roll, and pitch of the aircraft carrying the radar will cause the  real antenna beam to point incorrectly. To avoid degradation of the SAR due to angular  motions, the antenna must be stabilized.1.18 Roll and pitch angles can be stabilized by means  of gyroscopes. Yaw angle can be compensated by reference to a gyroscope or by" clutter-lock"  in which the antenna position is adjusted so as to maintain a symmetrical doppler spectrum  about zero frequency. 
 SIDE FOR CLARITY 4HE AREAS OF ALL THREE PLATES WERE FIXED AT  K  HENCE ALL THREE  PATTERNS RISE TO THE SAME AMPLITUDE AT BROADSIDE INCIDENCE ZERO ASPECT  4HE CENTER  PATTERN IS FOR THE DISK  WHILE THE FIRST AND THIRD ARE BOTH FOR A SQUARE PLATE (OWEVER  THE SQUARE PLATE WAS ORIENTED FOR A PRINCIPAL 
  SATELLITE  ALTIMETRY v * 'EOPHYS 2ES  VOL   PP n    2 $ 2AY  h!PPLICATIONS OF HIGH 
 Ifthesurface were aperfect conduc- tor, #would berradians for horizontal polarization (electric vector parallel tosurface) and zero forvertical polarization (magnetic vector parallel tosurface). We shall bechiefly concerned, however, with the surface ofthe sea, and toalesser extent with land, and these mediums behave more like dielectrics than conductors atmicrowave frequencies. For horizontal polarization itisstill true that ~=r,but forvertical polarization the situation ismore complicated. 
 !TLANTIC REGION v  )%%%  4RANSACTIONS ON !NTENNAS AND 0ROPAGATION   VOL   .O   *ULY    - 0 - (ALL  h%FFECTS OF THE TROPOSPHERE ON RADIO COMMUNICATIONS v ,ONDON )NSTITUTION OF  %LECTRICAL %NGINEERS    P    + $ !NDERSON  h2ADAR DETECTION OF LOW 
 December, 1972. 146.Brennan, L.E.,andl.S.Reed:Theoryof Adaptive Radar,IEEETrans.,vol.AES-9,pp.237-25~, March,1973. 147.Zahm,C.L.:Application ofAdaptive ArraystoSuppress StrongJammers inthePresence ofWeak Signals,IEEETrans.,vol.AES-9,pp.260---271, March,1973. 
 Differentiation ofEq.(7.34) showsthatthemaximum gaincorresponds toawavelength (7.35) Atthiswavelength thegainwillbe4.3dBbelowwhatitwouldbein·theabsencedferrors.The maximum gainisthen Po(D)2 Gmax=43'£(7.36) Thegainofanantenna isthuslimitedbythemechanical tolerance towhichthesurfacecanbe constructed andmaintained.102Themostprecisereflector antennas seemtobelimitedtoa precision ofnotmuchgreaterthanaboutonepartin20,000,whichfromEq.(7.36)corre­ spondstoadiameter ofabout1600wavelengths formaximum gain.Thebeamwidth ofsuchan antenna wouldbeabout0.04°withagainofabout68dB. Inpractice, theconstruction tolerance ofanantenna isoftendescribed bythe"peak" error,ratherthanthermserror.Theratioofthepeaktothermserrorisfoundexperimentally tobeabout3 :1.Thistruncation oferrorsoccurssincelargeerrorsusuallyarecorrected in manufacture. Theeffectoferrorsinarrayantennas andfurtherdiscussion oferrorsincontinuous apertures isgiveninSec.8.8. 
 The edge-on return for ver- tical polarization is well predicted by the straight-edge formula given in Table 11.1. AZIMUTH ASPECT ANGLE a (degrees) FIG. 11.11 RCS of a square flat plate 6.5 in along a side; X= 1.28 in. 
 S. Raven, “Requirements for master oscillators for coherent radar,” in Proceedings of the IEEE,   vol. 54, February 1966, pp. 
 SYNTHETIC APERTURE RADAR  17 .176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 where PTx-avg = average transmitted power, G = antenna gain, s = target radar cross  section (RCS), A = antenna aperture area, h = antenna efficiency, and the radar losses  are represented by ( Loss). For SAR, at qsq = 0, from Eq. 17.6,  tR VA=λ δ2cr (17.29) Thus  SNRLossTx-avg crTx-= =P G R kT F VP2 3 3 3 0 2 4λ σ π δ ( ) ( )a avg cr LossA R k T F V2 2 3 0 8η σ π λ δ ( ) (17.30) If a flat ground is being observed, then  σ σ δ δ ψ =0 crr/ cos  (17.31) where s  0 characterizes the ground RCS per unit area and dr = pixel width in slant  range. 
 TRICAL PERFORMANCE  PACKAGING  COOLING  AVAILABILITY  AND MAINTAINABILITY AT LOWER RADAR 
 This is not always easy in the case of  a cluttered image, and a great deal still depends on the field experience of the operator.  Examples of unprocessed B-scan data and the same corrected for spreading loss and  attenuation are shown in Figure 21.26 and Figure 21.27. Although a C-scan is essentially an x, y plane at a selected value of Z or range of  values of Z, many of the processes described in the previous section can be applied.FIGURE 21.26  B-scan unprocessed data ( Courtesy IEE ) FIGURE 21.27  B-scan data corrected for spreading loss and attenuation  (Courtesy IEE ) ch21.indd   33 12/17/07   2:51:45 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 TEMS IN %UROPE 4HE #/34 
 A related task for radar that is not military is the detection and interception of drug  traffic. There are several types of radars that can contribute to this need, including the  long-range HF over-the-horizon radar. Remote Sensing of the Environment. 
 Geosci. Remote. Sens. 
 13.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 13.6 QUANTIZATION EFFECTS Of concern here are errors peculiar to phased arrays, which are due to the quantization  of amplitude and phase and to the lobes that occur when these errors are repeated peri - odically. The effect on the gain and radiation pattern of random errors in the antenna  excitation function is discussed in Section 13.5. Phase Quantization. 
 Conv. Rec ., pt. 5,  New York, 1959, pp. 
 SCALE SUBSIDENCE OF AIR CAUSES HEATING AS THE AIR UNDERGOES COMPRESSION 4HIS LEADS TO A LAYER OF WARM  DRY AIR OVERLAY 
 Manyofthecivilianapplications ofradararealsoemployed bythemilitary. The traditional roleofradarformilitaryapplication hasbeenforsurveillance, navigation, and forthecontrolandguidance ofweapons. Itrepresents, byfar,thelargestuseofradar.. 
 Goddard, and S. M. Cherry, “Detection of hail by dual polarization  radar,” Nature , vol. 
 The first is that the intersection of a beam emitted from an antenna of finite height and the earth is the interior of a hyperbola and not a sector, as implied above. The second is that at close ranges the clutter is in the Fresnel re- gion of the antenna and the far-field gain formula no longer applies. In a more careful analysis, by using either of these factors, the integral may be shown to be convergent. 
 53, pp. 1406-1428, October 1965. 15. 
 Figure 12.22 shows the kind of sys- tem that may be used to measure scattering from within a volume. By determining the spectrum of the re- turn, the user can establish the scat- tering from different ranges. This system has been used in determining the sources of scatter in vegeta- tion25"27 and snow. 
 IZATIONS CAN BE VARIED FROM PULSE TO PULSE )F THE PHASES AS WELL AS THE MAGNITUDES OF THE ECHOES ARE OBTAINED  THEN SUCH A RADAR IS FULLY  POLARIMETRIC 7E MAY DESIGNATE THE CHOICE  OF POLARIZATIONS AS FOLLOWS (6 IS hTRANSMIT (  RECEIVE 6 v AND SO FORTH &ULLY POLARIMETRIC 3!2S HAVE BEEN DEMONSTRATED 3ULLIVAN ET AL  AND (ELD ET AL   &OR EXAMPLE  3ULLIVAN ET AL INCLUDES (( AND (6 8 
 Allwires that leave this well-shielded compartment gothrough . i j \k,I L. FIG.11.28.—Interior view ofa3-cm airborne r-fhead; (a) pulse input; (b) pulse trans- former; (c) pulse compartment; (d) pulse transformer bushing; (e) magnetron cathode bushing; (f) blower motor; (g) .4FC chassis; (h) receiver chassis; (i) beacon reference cavity; (j) shield for local oscillators; (k) double mixer; (1)TR tube. 
 For this reason, many solid-state transmit- ters consist of modules that feed either rows, columns, or single elements of an array antenna. Especially in the last-named case, it is necessary to build the mod- ules (and probably their power supplies) into the array structure. Furthermore, locating the modules at the antenna avoids the losses of long waveguide runs. 
 £ä°ÓÈ  2!$!2 (!.$"//+  AND ITS PREDECESSORS THE )/4 AND THE +LYSTRODE  ARE THE ONLY 2& POWER SOURCES THAT  CAN OPERATE EFFICIENTLY WHEN AMPLITUDE SHAPED WAVEFORMS ARE DESIRED FOR MINIMIZING OUT 
 CHEMICAL  STATE OF THE IONOSPHERE AND MODELS THAT DESCRIBE RADIOWAVE PROPA 
 16.6 oscillator isoff-tune. Taking A,=0.04 psec (for r=1~sec) and allow- ingaphase change of& cycle, wegetAj=~Me/see. Summary ofRequirements. 
 Figure 17.11 a shows a conventionally processed SAR  image containing three moving targets—a military truck (type M813), a tractor-trailer  truck, and a surrogate (i.e., a full-size replica) of a missile transporter-erector-launcher  (TEL). Figure 17.11 b shows the focused image of the tractor-trailer resulting from the  processing. The two-foot resolution clearly shows the outline of the cab and trailer of  the truck. 
 Deirmendjian. D.: Far-Infrared and Subrnillimeter Wave Attenuation by Clouds and Rain. J. 
 Long: A Luneburg Lens Scanning Systt:m, I RE Trans., vol. AP-5, pp. 21 25,  January. 
 442-447  in tracking radar. 172 INDEX 577  Multiple beams, in arrays, 310-318  Multiple-frequency CW radar, 95-98  Multiple prf, in MTI. 114-117  Mutual coupling, 306  n-bar scan, 178  Near field, antenna, 228  Neyman-Pearson observer, 376  Nodding-beam height finder, 541-542  Nodding scan, 178  Noise:  in angle tracking, 167-170  atmospheric, 461-463  environmental, 461-465  in range tracking, 177  Noise bandwidth, 18  Noise factor, 344  Noise figure, 344-347, 350-351  Noise jamming, 548-551  Noise temperature, 345-346  Noise-temperature ratio, 347  Nomenclature, letter band, 8  Noncoherent AMTJ, 147  Noncoherent integration, 29-32  Noncoherent MTI, 138-139  Nonlinear-contact scattering effects, 437  Nonlinear FM pulse compression, 431  Nonmatched filter, 374-375  Nonparametric detector, 393  Nonrecursive filter, 110  Nonwhite noise matched filter, 375  0-type tube, 200  Off-axis tracking, 174  Offset feed, 239  Oil slicks, 482  On-axis tracking, 180-181  Operator loss, 60-61  Operator, radar, 386--387  Optical processing, 523-526  Optimum detector law, 382-384  Organ-pipe scanner, 247-248  Over-the-horizon (0TH) radar, 529-536  Overall noise figure, 345  Palmer scan, 177  Parabolic cylinder, 235-236  Parabolic reflector antennas, 235-243  Parabolic torus, 236, 246--247  Paraboloid, 235  Parallel-fed array, 283, 285 . 
 8. Mengel, J. T.: Tracking the Earth Satellite, and Data Transmission by Radio, Proc. 
 W. H.: Improved MTI Radar Signal Processor, Report no. FAA-RD-74-185, MIT Lincoln  LahoratorJ'. 
 4.Ifsurface reflection ishigh, thelowest possible angle ofcoverage is raised from thehorizon toanangle a=k/2h, where aisinradians and histheheight oftheantenna above thesurface. Ifsurface reflection islow, radiation striking the surface islost. Itisclearly desirable tominimize this loss bybeam-shaping. 
 13 1. Snre;\u, J. C'.: Confornial Arrays Come of Age, Mic.rowatle J., vol. 
 ANGULAR SPIRAL  ANTENNA 4HE DISPERSIVE NATURE OF THIS TYPE OF ANTENNA CAUSES AN INCREASE IN THE DURA 
 WORLDv EFFECTS ! USEFUL FIGURE OF MERIT IS THE INTEGRATED SIDELOBE RATIO )3,2   DEFINED AS    )3,2 )NTEGRALOVER03&3IDELOBES )NTEGRALOVEER03&-AINLOBE    )3,2  IS USUALLY MEASURED IN D" A TYPICAL VALUE MIGHT BE  
 pp. 1639- 1653, July 1995  [Sch] R. Schneider, Modellierung der Wellenausbreitung für ein bildgebendes Kfz -Radar,  Dissertation an der Universitat Karlsruhe, Mai 1998   [TaK]  Y. 
 7.2 ARRAYTHEORY Array with Two Elements. Figure 7.4 shows two isotropic radiators which are spaced by a distance s and excited with equal amplitude and phase. With unity input power, the vector sum of their contributions, added at a great dis- tance as a function of 0, is the radiation pattern £ (0) = _!_ reJ(2ir/\)(s/2) sin 6 + £ -j(2-nl\}(sl2) sin 6j V2 where 0 is measured from the broadside direction. 
 1 incident power density/4~ (2.36)  R-+m  where R = distance between radar and target  E, = reflected field strength at radar  Ei = strength of incident field at target  This equation is equivalent to the radar range equationbf Sec. 1.2. For most common types of  radar targets such as aircraft, ships, and terrain, the radar cross section does not necessarily  bear a simple relationship to the physical area, except that the larger the target size, the larger  the cross section is likely to be. 
 The PI phosphor is commonly found in most A-scope presentations.  In order to achieve long decay times a two-layer, or cascade, screen is sometimes used, as  in the P7 or the P14. The first phosphor layer emits an intense light of short duration when  excited by the electron beam. 
 The theoretical accuracies with which range, rela-  tive velocity (doppler frequency), and angle of arrival can be determined are derived in  Sec. 11.3. This is followed by a treatment of the ambiguity function and its effect on waveform  design. 
 In a bulk ultrasonic device the input electrical signal is transformed into an acoustic wave, propagates through a medium at sonic speeds, and is then con- verted back to an electrical signal at the output. Since the wave propagates at sonic speeds, longer delays are achieved than with an electrical device of com- parable size. A major disadvantage of ultrasonic devices is that the transducers required for coupling electrically to the acoustic medium are inefficient energy converters and hence cause high insertion losses. 
 (ILL   ND %D   .EW 9ORK -C'RAW 
 The technology of millimeter wave  radars and the propagation effects of the environment are not only different from  microwave radars, but they are usually much more restricting. Unlike what is experi - enced at microwaves, the millimeter radar signal can be highly attenuated even when  propagating in the clear atmosphere. Attenuation varies over the millimeter wave  region. 
 10. H. Urkowitz, “The effect of antenna patterns on performance of dual antenna radar moving target  indicators,” IEEE Trans ., vol. 
 (14). 650 MOVING-TARGET INDICATION [SEC. 16.9 This expression iszero when fdisamultiple ofthe PRF and, since j,=2v/~, thefirst “blind” speed isgiven by f,T=2~T=1, or A Af, “=27=5’(15) where j,isthe PRF. 
 21, 450, 2001. 22. J. 
 REFLECTOR ANTENNAS  12.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 A phased array (ESA) type feed covering the focal region (planar or curved in  shape), such as that shown in Figure 12.31 b, can provide improved capability. It offers  two enhancements that extend the capability above and beyond that of a multiple feed  array with switched beams. The phased array fed reflector can transmit or receive  beams over continuous angles within the FOV whereas the multiple feed array is  limited to discrete beam positions. 
 DELAY -4) FILTER IS SHOWN IN &IGURE  4HE -4) RESPONSE HAS A PEAK VALUE OF    yD"  RESULTING IN AN AVERAGE NOISE GAIN OF  UNITY  AND THE STRAIGHT LINE APPROXIMATION FOLLOWS THE LOW FREQUENCY ASYMPTOTE UP TO THE  D" LEVEL  WHICH OCCURS AT  F 4     AND STAYS CONSTANT AT THE  D" LEVEL AT ALL  HIGHER FREQUENCIES 4HE JUSTIFICATION FOR THE  D" APPROXIMATION AT THE HIGHER FREQUEN 
 Between the sub -registers, the so - called cell under test (CUT) is located. Each sub -register has its own adding circuit. The larger  of the two sum -values (MAX) is normalized by dividin g it by the number of cells in the sub - register, L. 
 HORN SQUARE FEED TO A MAXIMUM OF  FOR THE -)4  
   PP n  -ARCH   - 3CHWARTZ  h! COINCIDENCE PROCEDURE FOR SIGNAL DETECTION v  )2% 4RANS  VOL )T 
 Wedges appear to model the qualitative behavior with  both polarizations fairly well at the lower grazing angles. Figure 15.21 also includes two additional simple scattering models for comparison.  Lambert’s law, mentioned in connection with Figure 15.9 a,b, expresses the cross sec - tion in the form s  0 = A sin2y , where A is the surface albedo . 
 241-243, IEEE Publication 75 CHO 938-1 AES.  37. Katzin, M., R. 
 11.17c, is a geometry that provides better performance ror large pulse-compression  ratios. 22 Shallow grooves etched in the delay path result in SAW reflections to form a delay  that depends on the frequency. The structure is less sensitive to fabrication tolerances than  convention'1 transducers. 
 ........................  17     . Radartutorial (www.radartutorial.eu)   2 Learning Objectives   The learning objectives are  a preview of the information you are expected to learn in this chapter. 
 Usingamodeloranantenna inwhichthereflector isdistorted byalargenumberofrandom gaussian-shaped bumps,Rllzeshowedthattheradiation patterncanbeexpressed as (7.31) where (;0(0.1J)istheno-error radiation pattern whoseaxialvalue(at0=0,¢=0)is Ila(rrlJ/A)2, ()istheantenna diameter, Paistheaperture efficiency, Cisthecorrelation interval ortheerror,andIIequalssinO.ThemeansquarephaseerrorPisassumed tobegaussian. The anglesO.1Jarethoseusuallyemployed inclassical antenna theoryandaredefinedinFig.7.28. Theyarenottobeconfused withtheusualelevation andazimuth angles.Theantenna liesin thex-yplaneofFig.7.28.Theerrorcurrentinoneregionoftheantenna isassumed independ­ entoftheerrorcurrents inadjacent regions. 
 AES-4, pp. 474-477, May, 1968.  18. 
 Subarrays. It is sometimes convenient to divide an array into subarrays. For example, the  AN/SPY-I AEGIS array utilizes 32 transmitting and 68 receiving subarrays of different   size^.^' One reason for dividing the transrriitting array into subarrays is to provide a dis-  tributed transmitter. 
 Pustovoytcnko: On Polarilation Features of Radio Signals Scattered  From the Sea Surface at Small Grazing Angles, J. Geopli;•s. Res., vol. 
 Although the apex-matching plate has a broader  bandwidth than matching devices inside the transmission line, it causes a slight reduction in  the gain and increases the minor-lobe level of the radiation pattern.  Offset feed.1 Both the aperture blocking and the mismatch at the feed are eliminated with the  offset-feed parabolic antenna shown in Fig. 7.10. 
 TANK MEASUREMENTS UNDER IDEALIZED CONDI 
 TERN AND CAN BE GENERATED BY TWO CASCADED DIGITAL INTEGRATORS 4HE INPUT DIGITAL COM 
 IEEE J. Sel. T op. 
 AC-7, pp. 2_7-32, July, 1962. TRACKING RADAR 189  73. 
 FICIENT STABILITY EXISTS FOR THE INTENDED APPLICATION #LOSE TO CARRIER PHASE MODULATION IS TYPICALLY DOMINATED BY THAT OF THE OSCILLATORS  DUE TO THE INHERENT FEEDBACK PROCESS WITHIN THE OSCILLATOR CIRCUITRY .OISE CONTRIBU 
 Table 19.4 contains the necessary data relative to the change of attenuation with  temperature and can be used with Table 19.3. To determine total attenuation caused by rainfall through a particular precipitation  path, something must be known or assumed about the nature of the precipitation itself  and, consequently, about how its rainfall rates and drop sizes are distributed in three  dimensions. A systematic vertical variation of R, decaying with height above a measured sur - face value, seems to be appropriate in stratiform53 rainfall, which is rain having a  widespread and continuous nature. 
 AIRBORNE MTI  3.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 The hybrid amplifier shown has two input terminals that receive Σ(q ) and j∆(q )  and amplify the ∆(q ) channel by kVx relative to the Σ(q ) channel. The output ter - minals produce the sum and difference of the two amplified input signals. Because  DPCA compensates for the complex signal, both amplitude and phase information  must be retained. 
 C. J.: High Resolution Land clutter Characteristics, IEE Conf. Publ. 
 PRESENT CLOUDS  THAT MASK THE PLANET /NE OF THE WIDEST USED AND LEAST EXPENSIVE OF RADARS HAS BEEN  THE CIVIL MARINE RADAR FOUND THROUGHOUT THE WORLD FOR THE SAFE NAVIGATION OF BOATS AND SHIPS 3OME READERS HAVE UNDOUBTEDLY BEEN CONFRONTED BY THE HIGHWAY POLICE USING THE #7 DOPPLER RADAR TO MEASURE THE SPEED OF A VEHICLE 'ROUND PENETRATING RADAR HAS BEEN USED TO FIND BURIED UTILITY LINES  AS WELL AS BY THE POLICE FOR LOCATING BURIED OBJECTS AND BODIES !RCHEOLOGISTS HAVE USED IT TO DETERMINE WHERE TO BEGIN TO LOOK FOR BURIED ARTIFACTS 2ADAR HAS BEEN HELPFUL TO BOTH THE ORNITHOLOGIST AND ENTOMOLOGIST FOR BETTER UNDERSTANDING THE MOVEMENTS OF BIRDS AND INSECTS )T HAS ALSO BEEN DEM 
 Oliphant, of Birming-  ham University, and Dr H. W. B. 
 The simplest way to shape the beam is to shape the reflector, as Fig. 6.11 il- lustrates. Each portion of the reflector is aimed in a different direction and, to the extent that geometric optics applies, the amplitude at that angle is the integrated sum of the power density from the feed across that portion. 
 Q-30 11 '"'"'"-40eu -50x NJresidential/~x x~ _x-----x-x Phoenixx "x"-><"x____ x x_xx-x __ ~-.X NJrural~ x / Arizona mountainous x X <""';:.(/x x~-- --=xy.:;;>,.----x Arizona desertx---x___ / NJmarshlandx~/x x_x Delaware Bayx-----. __-----'- l~~-l:.--L--'---l-JL.J..-=------'----L__=.__--'--~__::_'_:__:_'_--L.~ 3° 5° 10030° 60090· Grazing angle (d). 494 INTRODUCTION TO RADAR SYSTEMS  Grazing angle  Figure 13.10 Cross-section per unit area of ci~ltivated terrain illustrating th~: incrsast: or n" witti dccrrasing  grazing angle for small values of grazing angle. 
  TO HIGH 
 Ir a suitable device is used to measure 110, a target signal is said to be present if this number is  less than a predetermined (threshold) value and is said to be absent if the threshold is  exceeded. (The value or 110 is a maximum when S/N 0.)  Coherent detector. The coherent detector (Fig. 
 24, 25,   May 30, 2005. ch05.indd   45 12/17/07   1:27:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 This radar was a pulsed high-frequency (HF) radar which made height measurements by comparing am- plitudes of the (multipath-lobed) main beams of a pair of vertically mounted re- ceiving antennas. Conceptualized in Fig. 20.1/?, the technique was also utilized in early United States radars, notably, the Canadian-built United States radar SCR- 588, and the United States-built SCR-527, both based on the British Type 7 radar design.3 One of the earliest and perhaps most direct form of radar height finding was to mechanically direct and hold a narrow-elevation-beam antenna pointed toward the target. 
 J3. Saxton. J. 
 TRACKING  SYSTEMS v 0ROC )2%  VOL   PP n  -AY   - ) 3KOLNIK   )NTRODUCTION TO 2ADAR 3YSTEMS   .EW 9ORK -C'RAW 
 COMPRESSION SIDELOBES  IT IS STILL NECESSARY TO  CONTROL DETECTIONS FROM RESIDUE CAUSED BY THE SPECTRAL SPREAD OF THE CLUTTER OR BY LOW FREQUENCY TRANSMITTER POWER SUPPLY RIPPLE 4HIS CAN BE ACCOMPLISHED BY LIMITING THE MAXIMUM SIGNAL AMPLITUDE AT THE INPUT TO THE CANCELER 4HE PROCESS DESCRIBED ABOVE IS DEPICTED IN &IGURE  /NE APPROACH THAT HAS BEEN SUCCESSFUL IN ACHIEVING THE MAXIMUM -4) SYSTEM  PERFORMANCE ATTAINABLE WITHIN THE LIMITS IMPOSED BY SYSTEM AND CLUTTER INSTABILITIES &)'52%   0ULSE COMPRESSION WITH -4)  A  IDEAL BUT DIFFICULT 
 Quadratic residue (p. 254 of Ref. 26), or Legendre, sequences offer a greater selection of code lengths than are available from maximal-length sequences. 
 The usual value obtained was 4 –4.5 mA; operators were instructed to shut down the transmitter to prevent damage if readings of 8 mA or greater were observed (indicating a very high PRF). The transmitter also provided synchronising pulses to the indicator units from sockets on the front panel. Figure 2.5. 
 SERIES MODEL AND ARE CONSEQUENTLY LOW ENOUGH IN AMPLITUDE THAT THEY CAN OFTEN BE IGNORED &OR THIS REASON  A LOW )& GENERALLY PROVIDES BETTER SUPPRESSION OF SPURIOUS RESPONSES 4HE SPURIOUS 
 3 LFM waveform autocorrelation function ( T = 10 µs, B = 1 MHz,   TB = 10) FIGURE   8. 4 LFM waveform autocorrelation function ( T = 100 µs, B = 1 MHz,   TB = 100) to 0.01 MHz/µs. In this case, a doppler shift of 0.5 MHz shifts the peak of autocor - relation function to t  = 50 µs, an increase of a factor of ten compared to the result  for a 10-µs pulsewidth. 
 According to (6), the forward-looking image is moved back by 2 Δnan azimuth sampling units, and the side-looking image is moved back by Δnanazimuth sampling units. The images obtained from the three beams are fused in backward-looking image. 3. 
 Lawson: The Theoretical Precision with Which an Arbitrary Radiation  Pattcrn May Re Ohtailled wit11 a Source of Finite Size, J. IEE, vol. 95, pt. 
 With this relationship the rcccivcJ echo  power can be related to rainfall rate. A number of experimenters have attempted to determine  the constants in Eq. ( 13.20), but considerable variability exists among the reporteJ results. 
 By this means the trigger pulse to the indicator can be delayed a smallamount. Such a delay results in the sweep starting at the instant an echowould return to the indicator from a ﬂat plate right at the antenna not at theinstant that the pulse is generated in the transmitter. Line Voltage Accuracy of range measurement depends on the constancy of the line voltage supplied to the radar equipment. 
 Such coverage over the ocean is not practical because of  the unavailability of suitable sites for microwave radar. A shore-based HF OTH radar car1  cover large areas of the ocean and detect and track aircraft so as to provide air-traffic control.  For example, an OTH radar with 120' angle coverage and a range interval extending from  IOU0 to 4dk krn can survey an area of almost sixteen million square kilometers'. 
 \\\ S I N S I N \  N,   7 E ASSUME THAT  H  2 AND THUS  X y X y X   X    X  4HEN  WHERE  $X       \X   
 Labora- tory delay lines have been constructed consisting ofamercury-filled tray within which asupersonic beam isrepeatedly reflected from the side walls inany ofavariety ofgeometrical patterns until thebeam reaches the receiving quartz. Designs that have been proposed inthe past have appeared inferior tothe folded line asregards weight, size, orease of construction, and have consequently notbeen pursued totheengineering stage. Z’heFusedQuartzLine .—Solid media offer difficulties notencountered inliquids. 
   S I N    P    4HE BASELINE  , CAN BE DETERMINED USING '03 OR OTHER METHODS SUCH AS AN EMITTER LOCA 
 At microwave radar frequencies, the wavelength is small when compared FIGURE 26.1  Surface reflectionDirect pathReflected path ch26.indd   5 12/15/07   4:52:57 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation. 
 POLARIZED RADARS    $UAL POLARIZATION  4HE TRADITIONAL DEFINITION IS TRANSMISSION ON ONE POLARIZATION USUALLY LINEAR  SUCH AS (   AND RECEPTION ON THE LIKE 
 Clutlervisibility factor.Thesignal-to-c1utter ratio,aftercancellation ordoppler filtering, that provides statedprobabilities ofdetection andfalsealarm. Cllltlerattenuation. Theratioofclutterpoweratthecanceler inputtotheclutterresidueatthe output,normalized totheattenuation ofasinglepulsepassingthrough theunprocessed channelofthecanceler. 
 Guthrie, “Degradation analysis of pulse doppler radars due to sig - nal processing,” in NAECON 1977 Record,  pp. 938–945 and reprinted in D. K. 
 Van Meter: Detection and Extraction of Signals in Noise from the Viewpoint of  Statistical Decision Theory, J. Soc. Ind. 
 W.: MTI Radar, chap. 17 of" Radar Handbook," M. I. 
 Figure 13.23b shows amodification that canbeused when thesource hasa + u-+R>> R, w R l-r* x + ‘--cR,C>>T IEo (.).%2E, (b)Ex5EO FIG.13.24.—One-way triode clamps. (a) Positive clamp; (b) negative clamp. sufficiently low impedance but animproper d-c level. 
 TION OF A TOP AND BOTTOM HORN 4HIS ALLOWS THE  % 
   
 Watson, “IMMPDAF for radar management  and tracking benchmark with ECM,” IEEE Trans ., vol. AES–34, no.4, pp.1115–1134, 1998. 162. 
 One major limitation in conical-scan radars is that the AGC bandwidth  must be sufficiently lower than the scan frequency to prevent the AGC from removing  the modulation containing the angle error information. Phase-Comparison Monopulse.  A second monopulse technique is the use of mul - tiple antennas with overlapping (nonsquinted) beams pointed at the target. 
 Also, it cannot be employed when  the target angular extent is less than the sensitivity of the monopulse measurement.  Engine modulations. The radar echo from aircraft is modulated by the rotating propellers of  piston engines, and by the rotating compressor and turbine blades of jet engines.45 (The  compressor would be seen by a radar looking into the forward part of the jet aircraft and the  turbine when looking into the rear.) The characteristic modulations of the radar echoes from  aircraft can, in some cases, be used to recognize one type of aircraft from another; or more  correctly, one type of aircraft engine from another. 
 Various aspects of the performance were reported in [ 20]. The maximum detection ranges achieved were slightly greater than those measured with ASV Mk. VI in a Wellington. 
 The average annual temperature is 16.6◦C and the precipitation averages 1269 mm. The rainfall concentrates in early summer (May to July) [ 44]. Carbonate rock and soft soils, which might contribute to land subsidence, are widespread in Wuhan city, see Figure 1. 
 Class-B amplifiers  are biased such that conducting current in the transistor flows for exactly one half  of the input signal voltage swing. Push-pull amplifiers may be biased in this fashion  such that one transistor operates over the positive input signal swing, and the sec - ond transistor operates over the negative input signal swing. Higher efficiency but  higher distortion is experienced when compared with a Class-A design. 
 AP-K, pp.  242-246. May. 
 This can be substituted for cr, in Eqs. (4.25) and (4.26) to obtain the limitation to the improve-  ment factor caused by antenna scanning. These are  ni Ils= - (single canceler) 1.388  11 ",  IZs = - (double canceler) 3.853  These are plotted in Fig. 
 POLARIZED ON RECEIVE 4HEIR ANTENNAS ARE COMPRISED OF PASSIVE ARRAYS OF ( 
   PP n  3EPTEMBER   ,UDLOFF AND - -INKER  h2ELIABILITY OF VELOCITY MEASUREMENT BY -4$ RADAR v  )%%% 4RANS    VOL !%3 
 A minimum of three noncoplanar beams are needed to  determine the vector velocity, that is, the speed and direction of travel.  Doppler-navigation radar measures the vector velocity relative to the frame of reference  of the antenna assembly. To convert this vector velocity to a horizontal reference on the  ground, the direction of the vertical must he determined by some auxiliary means. 
 There is a three-stage velocity measurement process.  First, the surface is automatically acquired in range. Second, a fine range measurement  is made, often using monopulse discriminants and range centroiding similar to that  shown in Eq. 
 Any use is subject to the Terms of Use as given at the website. Radar Receivers.  RADAR RECEIVERS  6.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 In active array antennas, and many conventional antennas, low-noise amplifiers  (LNAs) establish the system noise floor prior to the receiver input. The noise from the  antenna is usually set well above the receiver noise floor such that the receiver has  only a small impact on overall system noise. 
 EYE  TECHNIQUE ARE " ,EWIS .2,  53!  AND $ (OWARD SEE THEIR PATENT ORIGINALLY FILED  THE  #ROSS 
 M. Goodman, J. Austin, M. 
 Curve A is the sum of all effects and is representative  of conical-scan and sequential-lobing tracking radars. Curve B does not include the amplitude  fluctuations and is therefore representative of monopulse radars. In Fig. 
 8 ADD 
 (2.45) power accepte y antenna rom its generator/4n  Note that the antenna gain is a function of direction. If it is greater than unity in some  directions, it must be less than unity in other directions. This follows from the conservation of  energy. 
 Racons have to include muting periods  to allow ship radars to look for small targets in the vicinity of the racon identifier. The long-term future of racons is unsure, although maritime authorities are assess - ing the situation.32 Mariners like them as they are useful, familiar, and give ship-relative  data. However, it is difficult to see how they will survive in their original form as marine  radar moves away from utilizing magnetron-based systems. 
 LENT DOPPLER FREQUENCY )F  FOR INSTANCE  THE RESPONSE IS  D" DOWN FROM THE MAXIMUM RESPONSE  THE LIMITATION ON  ) IS ABOUT  D" LESS SEVERE THAN INDICATED IN THE EQUATIONS  IN 4ABLE  )F ALL SOURCES OF INSTABILITY ARE INDEPENDENT  AS WOULD USUALLY BE THE CASE  THEIR INDIVIDUAL POWER RESIDUES CAN BE ADDED TO DETERMINE THE TOTAL LIMITATION ON -4) PERFORMANCE )NTRAPULSE FREQUENCY OR PHASE VARIATIONS DO NOT INTERFERE WITH GOOD -4) OPERATION  PROVIDED THEY REPEAT PRECISELY FROM PULSE TO PULSE 4HE ONLY CONCERN IS A LOSS OF SEN 
 TO 
 NALS HAVE BEEN PROCESSED BY THE HYBRID AMPLIFIER !FTER THIS SI NGLE 
 If in that  interval the trigger voltage is withdrawn from the grid  the circuit remains quiescent again until, the condenser  having charged once again, the discharged is ‘pipped  off.’  The difference graphically is that with continuous  working we obtain a succession of saw-tooth forms,  such as ~~ \ ~\_~ \_-~ \ .. The vertical por-  tion x is dependent on the discharging characteristics of  the thyratron. The sloping portion depends for its  slope and degree of linearity on the condenser and  voltage values, and, of course, on the anode voltage and  anode current characteristic of the screened pentode  used as a charging resistance. 
 10.9 WHICH RF POWER SOURCE TO USE? There is no good, simple answer to this question, but in this section we shall attempt  to discuss some of the various issues that might be involved. This chapter has briefly described the various vacuum tubes that have been used or  considered for radar applications, and the next chapter discusses the solid-state transmit - ter, which has also been widely used in radar. A question that naturally arises is which  RF power source should be used for some particular radar application. 
 typical microwave crystals. ~+5/ z ‘o -5 -2.0 -1,5 -1.0 -0.5 0+0.5 +1.0 Appliedvoltageinvolts ‘c= FIO.11.20.—Typical characteristic curve of FIG,ll 21.-Equivalent circuit asilicon rectifier. ofacrystal rectifier. 
 For example, the rms combination of the voltages (/ and Q) is complicated in linear format, and approximations are generally employed which introduce some error. In log format the process is simple and more accurate: Iog2 /2 = 2 Iog2 I/I Iog2 Q2 = 2 log IgI (3.14) Iog2 (I2 + Q2) = Iog2 /2 + Iog2 (1 + Q2II2) (3.15) The latter term of Eq. (3.15) is the output of a PROM, using Iog2 /2 - Iog2 Q2 as the address.FIG. 
  
 pt. IIIA, pp. 1554-1558, 1946. 
  &IGURE B  (OWEVER  COOLING IS ALSO NECESSARY AND PROVIDED  AS OBSERVED  BY THE COOLING COILS AROUND THE ABSORBING CONE. °£{  2!$!2 (!.$"//+  /F FURTHER CONCERN TO HIGH PRECISION MONOPULSE APPLICATIONS IS  DRIFT OF THE ELEC 
 RESOLUTION TROPOSPHERIC RADAR SOUNDING v  0ROC #OLLOQ 3PECTRA -ETEOROL  6ARIABLES  2ADIO 3CI  VOL   PP n    2 * +EELER  $ 3 :RNIC  AND # , &RUSH  h2EVIEW OF RANGE VELOCITY AMBIGUITY MITIGATION TECH 
 SPECIFIED TERMINAL CHARACTERISTICS ! MORE GENERAL CAPABILITY IS AVAILABLE WITH 0ROPLAB  !S THESE MODELS ARE BASED ON THEIR RESPECTIVE CLIMATOLOGICAL DATABASES  THEY ARE OF  NO USE FOR REAL 
 More complete descriptions will be found in the Radar  l/a11dhook.1  For the most part, this chapter discusses the tubes used in radar transmitters and not the  transmitters themselves. A transmitter is far more than the tube alone. It includes the exciter  and driver amplifiers if a power amplifier, the power supply for generating the necessary  voltages and currents needed by the tube, the modulator, cooling for the tube, heat exchanger  for the cooling system if liquid, protection devices (crowbar) for arc discharges, safety inter­ locks, monitoring devices, isolators, and X-ray shielding. 
 $OPPLER  "EAM 3PACE 34!0  4HE FINAL CATEGORY RESULTS FROM IMPLEMENT 
 91.White.W.D.:Double NullTechnique forLowAngleTracking, Microwave J.,vol.19,pp.35-38.60. December. 1976. 
 23 to 20.26 linear-beam amplifiers, 10.4 to 10.13.     I_18 Transmitters ( cont. ) klystrons, 10.5 to 10.8, 10.26 multiple-beam, 10.7 to 10.8 magnetrons, 10.14 to 10.16, 10.26 microwave power module (MPM), 10.13 modulators for, 10.23 to 10.24 MTBF of tubes, 10.6 to 10.7, 10.10, 10.15, 10.16 oscillator vs. 
 chap.33of"RadarHandbook." M.I.Skolnik (cd.).McGraw­ HillRookCompany. NewYork.1970. 16.Jlidayet. 
 17, pp.  61-64. February, 1974. 
 202-211, 1958. 9. "Final Engineering Report on Displaced Phase Center Antenna," vol. 
 or along-track, resolution or v/llfd, or  ).R ).R  ,5 = -~· = --= D /2  er 211Tj 2L~ (14.18)  which is what was obtained in Eq. ( 14.6) frqm the synthetic aperture model. (In the above, the  relations t''lj = L., = R).JD were employed.)  Range rl'Solution. 
 Bogler, Radar Principles with Applications to Tracking Systems, New York: John Wiley &  Sons, Inc., 1990, pp. 262–266. 61. 
 A given pulse-compression ratio BT can be obtained with N = T/(N/B) subpulses,  or N = TT, instead of the BT subpulses required for the phase-coded pulse. Pulse-  compression ratios as high as 10' and bandwidths of several hundred megahertz have been  obtained. 33 With the proper frequency-shift sequence, the sideloba level on a power basis is  l/N2 down from the main response.j4 However on the doppler axis of the ambiguity function  the resulting sidelobes are 1/N rather than 1/N2, which is the result of only N = TT  su bpulses. 
 ARY SEPARATING THE  SPECULAR REGIME  WHERE THE CROSS SECTION IS DECREASED BY SURFACE  ROUGHNESS  FROM THE  ROUGH 
 In most applications this inconvenience is usually accepted in order to achieve  the other advantages offered by the latching ferrite phase shifter. When used for both transmit  and receive, the phase shift must be changed between the two modes of operation. With  switchingspeeds of the order of microseconds, it is practical to reset the phase stlifters just after  transmission in order to receive. 
 BEAM SCATTEROMETER v  )%%% 4RANSACTIONS ON 'EOSCIENCE AND 2EMOTE 3ENSING   VOL   PP n    3 ( 9UEH  h-ICROWAVE REMOTE SENSING MODELING OF OCEAN SURFACE SALINITY AND WINDS USING  AN EMPIRICAL SEA SURFACE SPECTRUM v IN  0ROCEEDINGS )%%% 'EOSCIENCE AND 2EMOTE 3ENSING  3YMPOSIUM  !NCHORAGE  !+    3 'OGINENI  $ 4AMMANA  $ "RAATEN  # ,EUSCHEN  4 !TKINS  * ,EGARSKY  0 +ANAGARATNAM   * 3TILES  # !LLEN  AND + *EZEK  h#OHERENT RADAR ICE THICKNESS MEASUREMENTS OVER 'REENLAND  ICE SHEET v  *OURNAL OF 'EOPHYSICAL 2ESEARCH   VOL   PP n    3 ( 7ARD  ' 2 *IRACEK  AND 7 ) ,INLOR  h%LECTROMAGNETIC REFLECTION FROM A PLANE 
 In 1981, M. M. Weiner89 documented and evaluated all  unclassified measurements of σB0; however, its use was restricted to U.S. 
 The radiosonde is a balloon-borne package of instruments for obtaining such  ~neasurements.~~ Tlie data is telemetered back to the ground. One drawback of the radiosonde  is that it is generally a slow-response instrument, and is not always able to detect with  stlrficietit accuracy tlie significant refractive index gradients needed for obtaining an accurate  description or the ray patlls.  in some applicatioris a complete ray trace is not necessary; instead, only the amount by  which tlie rays are bent might be desired, or the error in elevation angle which occurs. 
 Wurman, “Accuracy of wind fields observed by a bistatic doppler radar network,”  Journal Ocean. Atmos. Tech. 
 Because  EM propagation effects are not just limited to radar frequencies, over time the initial  radar requirements for AREPS were expanded beyond simple radar detection appli - cations to include applications in communications and electronic warfare. AREPS is  the only approved EM system assessment application within the Department of the  Navy Chief Information Officer DON Applications & Database Management System  (DADMS). APM is the only accredited (by the Chief of Naval Operations) EM propa - gation (2 MHz to 57 GHz) model for use in Navy systems. 
 254-255, March, 1969.  36. Hitney, H. 
 DELAY 
 25itwas assumed that Lwasa constant, and acomparison of Eq. (34) with Eq. (33) shows this tobeapproximately true, since seco differs appreciably from unity only forvery short ranges. 
 ING TOWARD !TTU IN ORDER TO WITHDRAW TROOPS 2ADARS ONBOARD THE 533 .EW -EXICO  THE 533 0ORTLAND  AND THE 533 7ICHITA CONFIRMED THE RADAR CONTACTS /N THE ORDERS OF !DMIRAL 'IFFEN  THE 53 .AVY SHIPS OPENED FIRE 4HE FIRING CON TINUED FOR ABOUT HALF  AN HOUR DURING WHICH TIME   
 POLARIZATION IMAGES  (ENCE  WE DO NOT FIND MANY CATALOGS OF POLARIMETRIC SCATTERING RESPONSES .EVERTHELESS  MANY AUTHORS HAVE DESCRIBED THE USE OF POLARIMETRIC IMAGES 3OME OF  THE PAPERS USING THE TERM  POLARIMETRIC REALLY REFER TO THE USE OF JUST ((  66  AND (6  POLARIZATIONS WITHOUT REGARD FOR THE PHASE )N THIS SENSE  THEY ARE USING THESE IMAGES IN THE WAY THAT LIKE 
 A difficulty with many  existing radar systems is that they are really too effective for  collision-warning, and give more information than the pilot  needs. Any device which continually gives warning of any-  thing but potentially dangerous aircraft would be a dis-  traction, and therefore a menace, to a civil pilot.  We can easily see that among the tasks ahead for radar  are many ancillary jobs, some of which we can regard  only as curiosities. 
 120. Wciristock. W.: Computer Control of a hlultifunction Radar, RCA Engineer, vol. 
 A tracking radar which operates with phase information is similar to an  active interferometer and might be called an ilrrerferonteter radar. It has also been called  sir~rrtltclrreo~ts-pI~c~.~~-co,npnriso~t radar, or phase-co~npariso~t mortopldse. The latter term is the  one wliich will be used here. 
 azimuth error from the other. For example, the top scan position may be chosen as zero phase for a cosine function of the scan frequency. This provides a posi- tive voltage output proportional to the angle error when the target is above the antenna axis. 
 TO 
 (1 1.3) is proportional  to the rise time and is independent of the pulse width. An improvement in accuracy is ob-  tained, therefore, by decreasing the rise time (increasing the bandwidth) or increasing the  signal-to-noise ratio.  The actual estimate of the time delay obtained by determining when the leading or  trailing edge of the pulse crosses a threshold will depend on the value of the threshold relative  to the peak value of the pulse. 
 71. Doviak, R. J., et al.: Bistatic Radar Detection of High Altitude Clear Air Atmospheric Targets, Radio Sd., vol. 
 Plowman, J. C.: Automatic Radar Data Extraction by Storage Tube and Delay Line Techniques, J.  Brit. 
 AREPS  will execute on a personal computer (desktop or laptop) using a Microsoft Windows  operating system such as NT, 2000, XP, or Vista and requires no additional special  hardware. AREPS may be freely obtained at the URL listed in the first reference. Before continuing with the discussion of electromagnetic (EM) propagation mod - els and assessment systems, it is appropriate to discuss the natural environment and its  influence upon EM system performance. 
 Whinnery, Fields and Waves in Modern Radio , 2nd Ed., New York: John Wiley  & Sons, 1960, pp. 272–273. 24. 
   -5,4)&5.#4)/.!, 2!$!2 3934%-3 &/2 &)'(4%2 !)2#2!&4   x°£x 4HE SUBSUITE OF MULTI 
 12,Chap. 1). Comparing Eqs. 
 Inthisdetector. themedianv,lueoftheII received pulsesisfoundandcompared againstathreshold. Thisrequires thattheamplitudes oftheIIindividual samples (pulses)bestoredandthenarranged (ranked) inorderofamplitude tofindthemedian. 
 E. D. Sharp,” Triangular arrangement of planar-array elements that reduces number needed,”  IRE Trans ., vol. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 Because these curves show the signal-to-noise response for each output pulse from  the MTI canceler, the inherent loss incurred in a scanning radar with MTI processing  due to the reduction of the effective number of independent pulses integrated24 is not  apparent. 
 BIT $!# OPERATING AT UP TO A  
 ENGINE AIRCRAFT IS SHOWN IN  &IGURE  ! RELATIVELY LONG TIME SAMPLE IS NEEDED  SINCE SHORT TIME SAMPLES OF DATA CAN DEPART FROM THE GAUSSIAN SHAPE 5NUSUAL TARGETS MAY ALSO DEPART FROM GAUSSIAN DISTRIBUTED ANGLE NOISE $ELANO  GIVES DATA FROM TWO AIRCRAFT IN FORMATION THAT ARE  GAUSSIAN 
  WEST DIRECTION BY VARIOUS DISTANCES BASELINE  3IGNALS FROM ANY TWO CAN BE ADDED    TO FORM A BASELINE PAIR 4HE BASELINE RECEIVERS EMPLOY TRIPLE FREQUENCY CONVERSION WHERE THE PHASE DIFFERENCE OF THE SIGNALS RECEIVED BY THE ANTENNA PAIR IS PRESERVED IN A  
 POWER #7 RADAR )T BECOMES     3KY NOISE CONSISTING OF SUN  GALACTIC  AND ATMOSPHERIC NOISE IS ANOTHER SOURCE OF 2&)  WHICH CAN INCREASE THE  RECEIVERS NOISE TEMPERATURE BY A FACTOR OF n AT FREQUENCIES BELOW ^ -(Z (OWEVER  THIS INCREASE IS USUALLY  ORDERS OF MAGNITUDE SMALLER THAN 2&) FROM OTHER SOURCES AND CAN BE IGNORED.   ")34!4)# 2!$!2   ÓÎ°Î£ PARTICULARLY SEVERE WHEN THE RECEIVER IS LOCATED IN DIRECT ,/3 OF THE TRANSMITTER  WHICH  MUST OCCUR WHEN SURVEILLANCE OF LOW 
 CLUTTER IMPROVEMENT AT A SPECIFIC TARGET DOPPLER (OWEVER  SUCH A DESIGN WILL USUALLY  PROVIDE SUBOPTIMUM PERFORMANCE AT ALL OTHER TARGET DOPPLERS 4HE SINGLE EXCEPTION IS THE TWO 
 LANCE RADAR TO AN !2- ATTACK RELIES UPON WAVEFORM CODING TO DILUTE THE ENERGY IN THE FREQUENCY RANGE   THE MANAGEMENT OF RADIATED ENERGY IN TIME AND ALONG THE ANGULAR SECTORS  AND THE ADOPTION OF LOW SIDELOBES IN TRANSMISSION 4HESE ACTIONS MAKE IT MORE DIFFICULT FOR AN !2- TO HOME ON RADAR 7HEN AN !2- ATTACK IS DE TECTED  IT MAY BE  USEFUL TO TURN ON SPATIALLY REMOTE DECOY TRANSMITTERS TO DRAW THE !2- AWAY FROM THE RADAR SITE "LINKING WITH A NETWORK OF RADARS ACHIEVES BETTER RESULTS 4HE !2- TRAJECTORY IS USUALLY SELECTED TO ATTACK THE RADAR THROUGH THE ZENITH HOLE REGION ABOVE THE RADAR  WHERE ITS DETECTION CAPABILITY IS MINIMAL 4HUS  A SUPPLEMENTAL RADAR THAT PROVIDES A HIGH PROBABILITY OF DETECTION IN THE ZENITH HOLE REGION IS REQUIRED 4HERE ARE CERTAIN ADVANTAGES IN CHOOSING A LOW TRANSMITTING FREQUENCY 5(& OR 6(&  FOR THE SUPPLEMENTAL RADAR 4HE 2#3 OF THE !2- BECOMES GREATER AS THE WAVELENGTH OF THE RADAR APPROACHES THE MISSILE DIMENSIONS  CAUSING A RESONANCE EFFECT  ! LOW 
 SEC. 11.4] RESONANT CAVITIES 405 could beused forthewavelength carried bythewaveguide. Since, how- ever, thedistortion ofthenormal field bythestub supports ofthecoaxial line makes itimpossible torealize the calculated limit, the factor oftwo does notrepresent thefullsuperiority ofwaveguide. 
 Krolik, “Track association for over-the-horizon radar with a statistical  ionospheric model,” IEEE Trans. Sig. Proc ., vol. 
 Ê-"  -// 
 Angle fluctuations are due to random changes in the relative distance from radar to the  scatterers, that is, varying values of a. These changes may result from turbulence in the aircraft  (5.2)168INTRODUCTION TORADAR SYSTEMS Toreducetheeffectofamplitude noiseontracking, theconical-scan frequency shouldbe chosentocorrespond toa-lowva1ueofamplitude noise.Ifconsiderable amplitude fluctuation noiseweretoappearattheconical-scan orlobe-switching frequencies, itcouldnotbereadily eliminated withfiltersorAGe.Atypicalscanfrequency mightbeoftheorderof30Hz. Higherfrequencies mightalsobeusedsincetargetamplitude noisegenerally decreases with increasing frequency. 
 ENHANCED RADIAL VELOCITY DISPLAYS IS EASILY ACCOMPLISHED WITH TRAINED OBSERVERS  AND AUTOMATIC  DETECTION HAS BEEN IMPLEMENTED ON THE 4$72 RADAR SYSTEM 2ADIAL VELOCITY DIFFER 
 D. B. Trizna, “Estimation of the sea surface radar cross section at HF from second-order doppler  spectrum characteristics,” Naval Res. 
 These targets can be resolved at a resolu - tion probability of 0.9 with a false alarm probability of 0.01 at separations varying  between one-fourth and three-fourths of a pulse width, depending on the relative phase   difference between the two targets. Moreover, this result can be improved further by  processing multiple pulses. Automatic Detection Summary. 
 S. Johnson, and P. Z. 
 ch23.indd   29 12/20/07   2:21:53 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 
 In order to achieve long decay times a two-layer, or cascade, screen is sometimes used, as  in the P7 or the P14. The first phosphor layer emits an intense light of short duration when  excited by the electron beam. The light from the initial flash excites the second layer, emitting a  persistent luminescence. 
 It cannot be made broadband without a  decrease in efficiency. The slow-wave circuits of traveling-wave tubes have a broader band­ width than klystron resonant cavities; and when used for the output of a klystron, as in the.!  Twystron, a broad bandwidth cari be achieved with the peak and average power capabilities of  a klystron.  The C-band Varian VA-146 Twystron family of tubes provides peak power outputs from  200 kW to 9 MW with bandwidths greater than 10 percent. 
 orasinglemultimode horn.istheprinciple modification required oftheantenna. Although monopulse tracking radarsarecapahle of excellent accuracy. whenmonopulse isappliedtoa20surveillance radartheangleaccuracy is usuallypoor.Onereasonisthebroadelevation beamwidths. 
 TION REQUIREMENTS !S MENTIONED EARLIER  MOST (& SKYWAVE RADARS EMPLOY A BROAD TRANSMIT BEAM TO ILLUMINATE A ZONE OF INTEREST  AND THEN PROCESS THE ECHOES VIA A NUM 
 The divisions between the frequency regions are not as sharp in practice as the precise nature of the nomenclature. HF (3 to 30 MHz). Although the first operational radars installed by the British just prior to World War II were in this frequency band, it has many disadvantages for radar applications. 
 One of the earliest and simplest forms of electromechanical phase shifters is a transmis-  sion line whose length is varied n~echanically, as with a telescopic section. This is called a litle  .$rretclrcr. The telescoping section might be in the form of a " U", and the length of the line  changed in a manlier siniilar to that of a slide trombone. 
 (2.12). The customary definition, and the one recom- mended here, is the time duration between the half-power points of the envelope of the RF pulse (0.707-V points). For some purposes, such as analyzing the range resolution or accuracy, this arbitrary definition of the pulse length is not permis- sible. 
    
 Its chief limitation relative to the nonreciprocal toroid phase shifter is  its longer switching time, being of the order of 10 to 20 its. The switching speed is limited by the  shorted-turn effect of the thin metallic filni covering the ferrite roc!.  Other ferrite phase shifters. 
 British Patent 13,170, issued to Christian Hiilsmeyer, Sept. 22, 1904, entitled " Hertzian-wave Project-  ing and Receiving Apparatus Adapted to Indicate or Give Warning of the Presence of a Metallic  Body, Such as a Ship or a Train, in the Line of Projection of Such Waves."  3. Marconi, S. 
 FACE IS DIVIDED INTO RECTANGULAR GRID REGIONS OF AREA  D! THAT INTERCEPT THE INCIDENT FEED  FIELD )F THE FEED FAR 
 114. J. T. 
 Hoyle, “Clutter maps: Design and performance,” in IEEE Nat. Radar Conf. ,  Atlanta, GA, 1984. 
 In a radio  valve we heat a cathode, emit electrons from it, apply a  voltage to the anode, and the electrons complete their  journey. But what would happen if by some means such :  as applying a strong magnet to the outside of the valve  we prevented the electrons from completing their jour-  ney? We might thus visualize setting them whirling  round in a circle, and in the magnetron that is exactly  what we do.  On first switching on an anode voltage is applied, and  the hot filament emits electrons, which do not, however,  succeed in completing their journey to the anode. 
    
 A heterogeneous-SAR image registration method by normalized cross correlation is proposed in [ 9]. Frost ﬁltering is implemented on the SAR image and then the Gaussian gradient images of SAR image is used to form two Gabor characteristic matrixes, and then the normalized cross correlation matching is implemented on the two characteristic matrixes to achieve the registration of the image. The edge features of the target and the feature points can be extracted from the SAR image [ 10–13], and the SAR image registration is performed by the information. 
 Historically the term has been associated with the simultaneous generation and processing of a sum receive beam and a difference, or delta, receive beam. These beams are so named be- cause of the early and still common method used to form them, i.e., by adding and subtracting, respectively, the two halves of the antenna aperture. While this method is a relatively inexpensive way to produce a sum-difference beam pair, it is not necessarily the best way from a performance standpoint. 
 11.16, consists of a  piezoelectric substrate such as a thin slice of quartz or lithium niobate with input and output  interdigital transducers (IDT) arranged on the surface. The design of the IDT determines the  impulse response of the SAW delay line. Efficient electric-to-acoustic coupling occurs when the  Thermal compression .. 
 Phase control allows beams to be widened, for example, to reduce search time for the more elevated regions, where reduced ranges need less antenna gain. A separate rotating surveillance radar system may be added for extra coverage (at a second frequency) and to allow more emphasis on tracking. Monopulse Track. 
 SCALE BREAKER WAS SIMULATED BY SUBMERGING A HYDROFOIL ACROSS A  METER  WIDE CIRCULATING WATER CHANNEL DRIVE N BY  MEGAWATTS OF  TURBINE POWER  "UT MOST LABORATORY EXPERIMENTS ARE MORE MODEST  INVOLVING A LO NG  WAVE TANK  PERHAPS A METER OR TWO ACROSS  WITH THE WAVE SYSTEM PRODUCED BY EITHER A CONTROLLED WIND OR A PROGRAMMED WAVEMAKER 4O ILLUSTRATE A FEW OF THE EXPERIMENTS AND THEIR RESULTS +WOH AND ,AKE  MEASURED  8 
 Greenstein, “A generalized clutter computation procedure for  airborne pulse doppler radars,” IEEE Transactions on Aerospace and Electronic Systems,   vol. AES-6, pp. 51–61, January 1970 and reprinted in D. 
 H. Steyskal, R. A. 
 The  expanded metal mesh made from aluminum is a popular form. A nonsolid surface such as a  mesh offers low wind resistance, light weight, low cost, ease of fabrication and assembly, and  the ability tcrconform to variously shaped reflector surfaces.14 However, a nonsolid surface  Figure 7.10 Parabolic reflector with offset feed.  RADAR ANTENNAS 239 reflector iscalledanapex-matc!ling plate.Although theapex-matching platehasabroader bandwidth thanmatching devicesinsidethetransmission line,itcausesaslightreduction in thegainandincreases theminor-lobe leveloftheradiation pattern. 
 Usually assumptions are made that the antenna pattern has constant gain within the actual 3 dB points and zero gain outside, but this clearly is not an accurate description. If large targets appear in the locations illu- minated by the side of the main lobe or the minor lobes, their signals may contrib- ute so much to the return that it is signif- icantly changed. Since this changed signal is charged to the direction of the major lobe by the data reduction process, the re- sulting value for a° is in error. 
 Thismightheaccomplished withasingle-sideband generator (frequency translator) inserted between thedirectional couplerandtheRFmixerofFig.3.17.Thefrequency translation inthe reference signalpathisequivalent toadoppler shiftintheantenna path.Thefrequency excursion ofthemodulation waveform canbeadjusted byaservomechanism tomaintain the maximum oftheBesselfunction attheaircraft's altitude. Thefrequency translator isnot neededinanairborne doppler navigator sincetheantenna beamisdirected atadepression angle.Jtherthan90°andadoppler-shifted echoisproduced bythemotionoftheaircraft. l\latched filterdetection. 
    .OVEMBER   , " 7ETZEL  h/N MICROWAVE SCATTERING BY BREAKING WAVES v IN  7AVE $YNAMICS AND 2ADIO  0ROBING OF THE /CEAN 3URFACE  #HAP   / - 0HILLIPS AND + (ASSELMANN EDS   .EW 9ORK 0LENUM 0RESS    PP n  " , (ICKS  . +NABLE  * +OVALY  ' 3 .EWELL  * 0 2UINA  AND # 7 3HERWIN  h4HE SPEC 
 25.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 25 The cos(q i) column shows the cosine of this angle, which should be multiplied by  the result of each iteration, as shown in the equations above. In actual applications,  however, this cosine multiplication is not performed at every iteration. At each stage,  the implied factor that needs to be multiplied by the IQ outputs of the stage in order to  provide the correct answer is the product of all of the cosines up to that point, as shown  in the P [cos(q i)] column. 
 TO 
 , ( N I)¢. If the beam is scanned as a function of time. these phase  shifts also change as a function of time. 
  IS AN ENHANCED VERSION  OF 2!$!23!4 
 Ir the paraboloid renector is replaced by a spherical-rencctor surface, it is  possible to achieve a wide scanning angle because of the symmetry of the sphere. However, a  simple spherical renector does not produce an equiphase radiation pattern (plane wave), and the  pattern is generally poor. The term spherical aberration is used to describe the fact that the  phase front of the wave radiated by a spherical reflector is not plane as it is with a wave  1 a<liatcd by an ideal parabolic reflector. 
   42!#+).' 2!$!2   °Î THE IMAGE ENTERS THE ANTENNA MAIN BEAM  AND THE ERROR IS ESSENTIALLY THAT OF A TWO 
 MENTS WOULD BE VIOLATED 4ASKS  AND   AS DEFINED  ARE INCOMPATIBLE 4ASK  REMOTE SENSING OF OCEAN CONDITIONS  WOULD HAVE A MUCH LOWER PRIORITY AS  IT DEALS WITH SLOWLY VARYING PHENOMENA  SO IT WOULD NEED ONLY OCCASIONAL REVISITING 4HE SMALLER SECTOR SHOWN AS 4ASK   EXTENDING TO A RANGE OF  KM  IS REPRESENTATIVE OF THE COVERAGE OF AN (& SURFACE WAVE RADAR  AS USED FOR PROTECTING THE APPROACHES TO A PORT  FOR EXAMPLE 4HIS EXAMPLE IS TYPICAL OF THE SCHEDULING AND RESOURCE ALLOCATION PROBLEM THAT IS  CENTRAL TO (& SKYWAVE RADAR OPERATIONS #OMPROMISES ARE OFTEN UNAVOIDABLE 4HE  SITUATION IS FURTHER COMPLICATED BY THE CONTINUOUS VARIATION OF IONOSPHERIC PROPAGA 
 It has also been called the quantization error, a more descriptive name. The average  number of cycles N of the beat frequenc;y fb in one period of the modulation cycle/~ is .Tb !fm,  \  where the bar over Ji, denotes time average. Equation (3.11) may be written as  · ,·, ·· cN  . 
 Muha, “Imaging antenna arrays,” IEEE Trans , AP130, (Q), pp. 533–540,  1982. 32. 
 AP-4, pp. 619-627, October, 1956.  81. 
 Although Eq. 15.16 successfully predicts (to 1st-order) the clutter returns at HF  frequencies, at microwave  frequencies the small-waveheight assumption on which  this model rests is violated on any real sea surface. The small-waveheight condition  expressed by Eq. 
 2025–2027, 2001. 91. R. 
 CODED WAVEFORMS  THE PULSE IS SUBDIVIDED  INTO A NUMBER OF SUBPULSES EACH OF DURATION  C    4. WHERE  4 IS THE PULSEWIDTH AND  .  IS THE NUMBER OF SUBPULSES 0HASE 
 However, when a  planar array is electronically scanned, the change of mutual coupling that accoinpanies it  change in beam position makes the maintenance of low sidelobes more difficult.  If an array has some margin in performance to permit graceful degradation, it is likely  that this margin will be eliminated during the procurement process if the cost of the radar  escalates. Even if the radar is delivered with margin for graceful degradation, it is likely that  after some time in operation it will always be at the degraded level because of a desire to keep  maintenance costs to a minimum. 
 SCALE TEST OBJECTS OR SCALE MODELS THEREOF 3MALL TARGETS OFTEN MAY BE MEASURED INDOORS  BUT LARGE TARGETS MUST USUALLY BE MEASURED ON AN OUTDOOR TEST RANGE 4HE CHAR 
 A guard beam with a near-omnidirectional pattern is formed for  sidelobe detection blanking as discussed in Section 4.2. Receiver/Protector (R/P).  The receiver/protector is a low-loss, fast-response,  high-power switch that prevents the transmitter output from the antenna’s duplexer  from damaging the sensitive receiver front end. 
 (a) Normal antenna pattern; (b)  cosecant-squared pattern. RADAR ANTENNAS 261  where all angles in the above formulas are measured in radians. For example, if 00 = 6° and  Om= 20°, the gain is reduced by 2.2 dB compared with a fan beam 6° wide. 
 MIT Radiation Laboratory Series. McGraw-  Hill Book Company. New York. 
 [ CrossRef ] 11. Wang, J.; Kasilingam, D. Global range alignment for ISAR. 
 Separate monopulse sum and  difference patterns, each with its own optimum shape, are also possible.  Graceful degradation. The distributed nature of the array means that it can fail gradually  rather than all at once (catastrophically). 
 $OWN .%$  VELOCITY ERRORS AND ESTIMATES OF STATISTICAL ACCURACIES 3NIFF OR 0ASSIVE ,ISTENING  -OST MODES HAVE A PRECURSOR SUBPROGRAM CALLED  SNIFF  WHICH LOOKS FOR PASSIVE DETECTIONS IN A TENTATIVE OPERATING CHANNEL BEFORE ANY  RADAR EMISSIONS IN THAT CHANNEL 4HE DETECTIONS COULD BE A FRIENDLY INTERFEROR  A JAMMER   OR AN INADVERTENT INTERFEROR SUCH AS A FAULTY CIVILIAN COMMUNICATIONS TRANSPONDER   4HIS LAST EXAMPLE IS THE MOST COMMON IN THE AUTHORS EXPERIENCE )T IS NOT UNCOMMON FOR A FAULTY TRANSPONDER TO APPEAR AS A MILLION SQUARE METER TARGET $OPPLER "EAM 3HARPENING $"3     $"3 IS VERY SIMILAR TO SYNTHETIC APER 
 CURRENTLY FOR MEASURING PRECIPITATION RATES !S AN EXAMPLE  THE DESIGN OF ELLIPTIC -4) FILTERS AS USED IN THE 4$72 WILL BE  DESCRIBED 4$72 IS A # 
 Therange anddoppler frequency shiftcanalsobecontinuously tracked, ifdesired, byaservo-control loopactuated byanerrorsignalgenerated intheradarreceiver. Theinformation available fromatracking radarmaybepresented onacathode-ray-tube (CRT)displayforactionbyan operator, ormaybesupplied toanautomatic computer whichdetermines thetargetpathand calculates .itsprobable futurecourse. Thetracking radarmustfirstfinditstargetbeforeitcantrack.Someradarsoperate ina search,oracquisition, modeinordertofindthetargetbeforeswitching toatracking mode. 
 Some sort of timing mark must be applied  to a CW carrier if range is to be measured. The timing mark permits the time of transmission  and the time of return to be recognized. The sharper or more distinct the mark, the more  accurate the measurement of the transit time. 
 Mumford, “Some technical aspects of microwave radiation hazards,” Proc. IRE , pp. 427–447,  February 1961. 
 Krizhevsky, A.; Sutskever, I.; Hinton, G.E. Imagenet classiﬁcation with deep convolutional neural networks. In Proceedings of the Advances in Neural Information Processing Systems, Lake Tahoe, NV , USA, 3–6 December 2012; pp. 
 ING COURSE OR PASSING CLOSE TO OTHER TARGETS !)3 HAS REASONABLY GOOD CAPABILITY IN NON 
 Allen, R. Sadler, T. Alcorn, J. 
 The radiation ofboth the electric and themagnetic dipole must therefore beconsidered. Wethen obtain (6) 3.3.Scattering ofaPlane Wave byaSphere.—The general problem ofscattering ofaplane wa~e byasphere issolved indetail inJ.A. Stratton’s book, Electromagnetic Theory (pages 563 ff),and references to the original papers can befound there. 
 TT    WHERE KMAX IS THE MAXIMUM FREQUENCY TRAPPED   C. IS THE REFRACTIVE INDEX CHANGE  ACROSS THE DUCT  AND T IS THE DUCT THICKNESS )N ADDITION TO EXTENDED RADAR RANGES  ATMOSPHERIC DUCTS AND OTHER PROPAGATION  EFFECTS SUCH AS MULTIPATH INTERFERENCE  HAVE OTHER SIGNIFICANT IMPACTS UPON RADAR PER 
                    &)'52%  2EDUCED DIMENSION 34!0 ARCHITECTURES. 
 issued Jan. 6. 1953. 
 On the other hand, a radar control can be made to automatically recognize when environmental con- ditions have changed and automatically select, without the aid of an operator, the proper radar operating parameters to maximize performance. Waveform. The most common radar waveform is a repetitive train of short pulses. 
 (This assumes that O, 10, and (IE /O,  are integers, where OA is the total azimuth coverage and oE the total elevation coverage, such  that R 2: OABE.) The antenna gain can be written as G = 4n/Ro. With the above substitutions  into Eq. (2.54) the radar equation for a search radar becomes  This indicates that the important parameters in a search radar are the average power and the  antenna effective aperture. 
 Furthermore, theradarechowilldependonthemoisture contentof thesurfacescalterers, snowcover,andthestageofgrowthofanyvegetation. Buildings, towers, andotherstructures givemoreintenseechosignalsthanforestsorvegetation because ofthe presence offlatreflecting surfacesand"cornerreflectors." Bodiesofwater,roads,andairport runways backscatter littleenergybutarerecognizable onradarPPIdisplays asblackareas amidthebrightness ofthesurrounding groundechoes.Ahillwillappeartostandoutinhigh reliefonaPPI.Thenearsideofthehillwillgivealargereturn,whilethefarside,whichis relatively hiddenfromtheviewoftheradar.willgivelittleornoreturn.Theradarcross sectionofafarmer's fieldwilldifferbeforeandafterploughing, aswellasbeforeandafter harvesting. Itwillalsodependonthedirection oftheradarbeamrelativetothedirection of theploughed furrows. 
 ING AMBIGUITIES (OWEVER  BY DEFAULT  THE MINIMUM RANGE FOR A SPACE 
   OPERATING IN THE ORBIT ORIGINALLY DESIGNED FOR 4/0%80OSEIDON 4HE ORBIT PARAMETERS INCLUDE REPEAT PERIOD  CALENDAR DAYS UNFORTUNATELY  OFTEN STATED AS  DAYS  INCLINATION  n REPEAT TRACK SEPARATION AT THE EQUATOR  KM  AND  ALTITUDE  KM 4HE RADIAL COMPONENT OF PRECISION ORBIT DETERMINATION 0/$  IS ON THE ORDER OF  CM FOR 40  AND *ASON 
 Ratios of copolarized main-beam peak gain to cross-polarized gain anywhere in the antenna pattern should be greater than 25 dB to provide protection against common cross-polarized jamming. This is thought of as an ECCM technique, but it is really no more than good antenna design. The cross- polarized jamming in this case attacks a design deficiency in the radar. 
 Most definitions of pulse shapes include voltage parameters, with rise and fall times being represented by 10 and 90 percent points and pulse duration by 50 percent (6 dB) points. Like- wise, filter bandpass characteristics are often defined by their widths at the 6 and 60 dB points. The 6 dB definitions will be the dominant definitions employed in this chapter. 
 ORDER "RAGG LINES AND SECOND 
 Angle resolution requires (electrically) large antennas. Resolu- tion in the cross-range dimension is usually not as good as the resolution that can be obtained in range. However, when there is relative motion between the indi- vidual parts of a target and the radar, it is possible to use the inherent resolution in doppler frequency to resolve in the cross-range dimension. 
 2007 ,16, 2023–2027. [ CrossRef ][PubMed ] 8. Iglesias, R.; Mallorqui, J.J. 
 TRIAL METAL OBJECTS IS GENERALLY ATTRIBUTED TO (ÓLSMEYER IN   BUT THE FIRST DESCRIPTION OF THEIR USE FOR LOCATION OF BURIED OBJECTS APPEARED SIX YEARS LATER IN A 'ERMAN PATENT BY ,EIMBACH AND ,WY 4HE WORK OF (ÓLSENBECK IN  APPEARS TO BE THE FIRST USE OF PULSED TECHNIQUES TO DETERMINE THE STRUCTURE OF BURIED FEATURES (E NOTED THAT ANY                
 POLARIZED COMPONENTS SUCH AS ( AND 6  )N A TRADITIONAL DUAL 
 HIGH 
 Self-pumping Lower Smaller Medium -55 dB -70 dB TT mode during rise and fall if cathode-pulsed; full-power noise output if turned on without RF drive A few decibels None, or turnoff electrode Permanent magnet 0.05-0.2 0.5-3.0° per 1% A /// . ond harmonic, -30 dB at the third harmonic, and considerably less at higher har- monics. Although these figures vary greatly from one tube design to another, there is no strong difference between linear-beam tubes and CFAs in general. 
 D. N. Held, “The NASA/JPL multipolarization SAR aircraft program,” Dig. 
 Ithas been found farmore effective toconvey theinformation through themedium ofperiodic signals whose frequencies orrepetition rates areseveral times those involved inthescanning and whose characteristics areinsome way descriptive ofit. Since scanning frequencies lieinthe interval from zero toafew cycles per second, the scanner data signals usually have periodicities intheaudio range. The signals mentioned above can take either oftwo forms. 
 This  blanked region in doppler is known as the main-beam clutter notch . The choice between these options is a trade-off of quantization noise and com - plexity versus the filter-weighting loss. If a canceler is used, filter weighting can be  relaxed over that with a filter bank alone, since the canceler reduces the dynamic- range requirements into the doppler filter bank (if the main-beam clutter is the largest  signal). 
 H. Hibbs: A New Microwave Reflector, Nal'al Research Lah. Rept. 
 Power isextracted from only one ofthe oscillating cavities. This may bedone bymeans ofeither acoaxial line output orawaveguide output. For the coaxial line output, itisusual toinsert aloop L(Fig. 
 Practical design dificultiies increase atpulse Iengths outside this range. The voltage across themagnetron when itisoscillating vigorously ina steady state isdesignated asV-o. Ingeneral, V~ti will liebetween afew kilovolts and 30to40kv,although itmay behigher formagnetrons inthe 1O-MW region. 
 The frequency-response function of the matched filter is the conjugate of the spectrum of  the received waveform except for the phase shift exp (- j2rcftl). This phase shift varies uniformly  with frequency. Its effect is to cause a constant time delay. 
 FICIENT TO ILLUMINATE THE REQUIRED RANGE DEPTH IN GENERAL  THIS IS AUTOMATICALLY SATISFIED OWING TO THE COST AND COMPLEXITY OF AN ANTENNA ABLE TO FORM A BEAM NARROWER THAN THIS IN THE VERTICAL PLANE &OR MOST SCENARIOS  ANY SENSITIVITY GAINED BY DIRECTIVITY IN ELEVATION DIRECTLY IMPROVES RADAR PERFORMANCE  SINCE INSTANTANEOUS RANGE DEPTH IS GENERALLY LIMITED BY IONOSPHERIC EFFECTS 4HIS IS IN CONTRAST WITH AZIMUTH DIRECTIVITY FOR TRANSMITTING  WHERE AN INCREASE IN DIRECTIVE GAIN IS ACCOMPANIED BY A DECREASE IN AREA COVERAGE &OR NOISE 
 SEC. 145] VOLTAGE REGULATORS 563 the normal full-load current. Such high starting currents cause: (1) excessive brush wear, (2) voltage dip onaircraft electrical system, (3)excessive load oncontactor points unless anoversize contactor isused. 
 AHEAD ALONG THE WATERWAY 4HE MAXIMUM DISPLAY RANGE ON THE SHORTEST SCALE IS TYPICALLY  METERS 4HESE RADARS ARE NORMALLY DESIGNED TO MEET REQUIREMENTS FOR RADARS ON VESSELS NAVIGATING THE 2IVER 2HINE  2ADARS FOR THE FISHING AND LEISURE MARKETS ARE NOT COVERED BY 3 /,!3 5NTIL    SUCH RADARS DID NOT HAVE AN INTERNATIONALLY RECOGNIZED STANDARD FOR MANUFACTURERS TO FOLLOW )%#   IS NOW THE AGREED INTERNATIONAL RADAR STANDARD FOR hCRAFT NOT IN  COMPLIANCE WITH )-/ 3/,!3 #HAPTER 6v AND WAS INITIALLY ISSUED AT THE INSTIGATION OF MANUFACTURERS .OW AN INCREASING NUMBER OF NATIONAL MARITIME ADMINISTRATIONS ARE INSISTING THAT ALL NEW SMALL CRAFT RADARS SOLD IN THEIR JURISDICTION CONFORM TO THIS STANDARD )%#  RECOGNIZES THREE CLASSES OF RADAR #LASS !  IS INTENDED FOR COM 
 5.IO TRACKING WITH SURVEILLANCE RADAR  The track of a target can be determined with a surveillan~ radar from the coordinates of the  target as measured from scan to scan. The quality of such a track will depend on the time  between observations, the location accuracy or each observation, and the number of extra­ neous targets that might he present in the vicinity of the tracked target. A surveillance radar that  develops tracks on targets it has detected is sometimes called a track-while-scan (TWS) radar. 
 £x°{ä  2!$!2 (!.$"//+   $ 4RIZNA  h-EASUREMENT AND INTERPRETATION OF .ORTH !TLANTI C /CEAN -ARINE 2ADAR 3EA 3CATTER v  .AVAL 2ES ,AB 2EPT   -AY   0 "ECKMANN   0ROBABILITY IN #OMMUNICATION %NGINEERING   .EW 9ORK (ARCOURT  "RACE AND 7ORLD   )NC    3ECT   ' 6 4RUNK  h2ADAR PROPERTIES OF NON 
 Probabilistic Notation. It has been mentioned (Sec. 2.1) that the radar signal detection process is basically probabilistic or statistical in nature. 
 349–357, 1966. 122. D. 
 TO 
 The aspect entropy value of dihedral A and the top-hat have a large difference between these shapes. The scattering mechanisms of dihedral B and the trihedral are similar. It seems that the values are closed but the difference is big enough to discriminate them. 
 140 HOW RADAR WORKS  is varied, of course, to produce illumination at different  ranges.  With basic types of H2S there is a common T and R  aerial system, the magnetron and Sutton-tube local  oscillator are used, and a ‘gas-gap’ switch to connect  alternately the high-power transmitter and then the  sensitive receiver and crystal mixer to the array. The  gas gap consists of two electrodes in a soft valve. 
 2.1to2.6arewholly geometrical ones inthesense that thefactors upon which thereceived power Sdepends arealllengths, apart from transmitted power P,towhich, ofcourse, Sisalways proportional. THE RADAR EQUATION FOR FREE-SPACE PROPAGATION 2.1. The Meaning ofFree-space Propagation.-Fortunately,the the quasi-optical nature ofmicrowave propagation permits ustoconcentrate our attention atthe outset onavery simple case, which weshall call “free-space propagation.” The circumstances implied would berealized exactly ifradar setand target were isolated inunbounded empty space. 
 Helical radiating elements have also been used in arrays to obtain phase shift$ by rotat ion of  the elements.62  A change in phase in the waveguide transmission may be obtained by mechanically  changing the dimensions of the g~ide.~'.~~ One such device that has been applied to practical  radars is the Eagle scanner, or delta-a scanner. The latter term is descriptive of the fact that the  velocity of propagation, and therefore the phase, of a signal propagated through a waveguide  depends on the width of the guide, or its "a" dimension. This phase shifting technique has  been used for GCA (ground control approach) radars to mechanically scan fan beams in  azimuth and elevation. 
 -ODE  3!2 ! 3IGNAL 
  AND SERIES 
 PLUS  MODEL  WHICH INCORPORATES THE EFFECTS OF BREAKING WAVES )N THIS CASE  THE "RAGG MODEL AND THE TWO 
 More often, atrain ofswitches isnecessary toseparate the various pulses from one another after decoding sothat noswitch is necessary atthe input circuit. Somewhat more elegant methods which allow narrower open intervals canbeused incertain special cases inwhich the opening ofthe switch can becontrolled from asequence ofevents within the cycle. Various arrangements will appear inlater sections in connection with specific methods ofdata transmission. 
 , 
 It has been reported29 that the rms value of the range  rioisc is approximately 0.8 of tlie target length when tracking is accomplished with a video  split-range-gate error detector.  5.7 ACQUISITION  A tracking radar must first find and acquire its target before it can operate as a tracker.  Therefore it i~.usually necessary for the radar to scan an angular sector in which the presence  of the target is suspected. 
 TIVE   THE MINIMUM PERPENDICULAR DISTANCE IS CALCULATED FOR ROAD SEGMENTS INSIDE THE  
 TO 
 IMPULSE 
 Stripmap SAR (or “strip” SAR) is also sometimes called “search”  SAR, since it is useful for imaging large areas at relatively coarse resolution. In strip - map SAR, the beam remains normal to the flight path (the latter is assumed to be a  straight line at constant altitude) and continuously observes a swath  (or strip) of terrain  parallel to the flight path extending from some minimum range Rmin to some maximum  range Rmax from the flight path. ch17.indd   3 12/17/07   6:48:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 no. 2, pp. 8.- 14. 
 A timing mark can  be a short pulse (an amplitude modulation of the signal), but it can also be a distinctive  modulation of the frequency or phase. The accuracy of a range measurement depends  on the radar signal bandwidth: the wider the bandwidth, the greater the accuracy. Thus  bandwidth  is the basic measure of range accuracy. 
 IFIED RANK DETECTOR  CALLED THE MODIFIED GENERALIZED SIGN TEST -'34    MAINTAINS  A LOW 0FA AND IS SHOWN IN &IGURE  4HIS DETECTOR CAN BE DIVIDED INTO THREE PARTS  A RANKER  AN INTEGRATOR IN THIS CASE  A TWO 
 ERY HAS PROVEN TO BE VALUABLE FOR A WIDE VARIETY OF APPLICATIONS  FROM OCEANOGRAPHIC OBSERVATIONS THE THEME THAT MOTIVATED 3EASAT  TO MEASUREMENT OF MILLIMETER 
 OUS CASE BEING IN THE 5NITED +INGDOM IN   WHEN THE GRAVESITES  UNDER CONCRETE AND IN THE HOUSE OF  &RED 7EST  OF THE  VICTIMS OF THE SERIAL MURDERER WERE PINPOINTED  )N "ELGIUM  THE GRAVESITES OF THE VICTIMS OF THE PEDOPHILE  $UTEOUS  WERE DETECTED IN  &)'52%   4YPICAL RADAR IMAGE OF CONCRETE FLOOR SHOWING REARS  JOINTS  MESH  ETC  NS PULSE 
 Radar may be itsed to give an up-to-  date pattern of precipitation in the area around the radar. It is a simple and inexpensive gauge  for measuring the precipitation over relatively large expanses. As a rain gauge it is quite useful  to the hydrologist in determining the amount of water falling into a watershed during a given  period of time. 
  
 C. Cooper and J. W. 
 141  delay-line canceler, 104- 1 14  digital processing. 119 -125  doppler filter bank. 127  double delay-line canceler, 109  DPCA, 143-144  externally coherent, 138  filter bank. 
 The double accumulator architecture, comprising the frequency  and phase accumulators, enables the generation of CW, linear FM (chirp), nonlinear  (piece-wise linear) FM, frequency modulated, and phase modulated waveforms. CW  waveforms are generated by applying a constant frequency word (digitized frequency  representation) input to the phase accumulator, creating a linear phase sequence that is  first truncated then input to a cosine (or sine) lookup table that outputs the correspond - ing sinusoidal signal value to the digital-to-analog (D/A) converter. The frequency  resolution is dependent on the number of bits and the clock frequency of the phase  accumulator. 
 PURPOSE #OMPUTERS  4HIS ARCHITECTURE EMPLOYS MULTIPLE GEN 
 Collector current is drawn only when the input voltage exceeds the reverse bias across the input and the output voltage is developed across a resonant-tuned load. The net result is high amplifier efficiency. The practical implications of a Class-C-biased amplifier stage are as follows: 1. 
 Equation 1. Radar Range Equation   The radar equation relates the expected receive  power (P r) to  the transmitted pulse p ower (P t); based on transmit antenna  gain (G t), area of the receive antenna (A r), target cross section  (aka reflectivity) σ, range from the transmitter antenna to the  target (R t), and range of the target to the receive antenna (Rr).  Unlike many communications systems, radar systems suffer  from very large signal path losses. 
 NALS OF STANDARDIZED AMPLITUDE TO RADAR RANGE  VELOCITY  AND ANGLE PROCESSING 
 Nu, “The propagation of a radar pulse in sea water,” J. Appl. Phys .,   73, (4), pp. 
 Received: 14 May 2019; Accepted: 9 July 2019; Published: 11 July 2019 /gid00030/gid00035/gid00032/gid00030/gid00038/gid00001/gid00033/gid00042/gid00045 /gid00048/gid00043/gid00031/gid00028/gid00047/gid00032/gid00046 Abstract: Building deformation models consistent with reality is a crucial step for time-series deformation monitoring. Most deformation models are empirical mathematical models, lacking consideration of the physical mechanisms of observed objects. In this study, we propose an improved time-series deformation model considering rheological parameters (viscosity and elasticity) based on the Kelvin model. 
 DARD METAL SPHERES DROPPED FROM AIRCRAFT  AND WIND SPEEDS AND WAVEHEIGHTS WERE RECORDED IN THE MEASUREMENT AREAS FROM SHIP INSTRUMENTS 4YPICALLY  SAMPLES OF  R    FOR A GIVEN SET OF RADAR AND ENVIRONMENTAL PARAMETERS ARE  SCATTERED OVER A WIDE RANGE OF VALUES AND IN THE .2, MEASUREMENTS WERE ORGANIZED INTO PROBABILITY DISTRIBUTIONS OF THE TYPE SHOWN IN &IGURE  4HE DATA  REPRESENTED BY THE SOLID LINE  ARE PLOTTED ON NORMAL PROBABILITY PAPER WITH 2AYLEIGH AND LOG 
 BASED %3- EQUIPMENT ! HIGH DEGREE OF MOBILITY FOR TACTICAL SYSTEMS ALLOWS hRADIATE AND RUNv OPERATIONS  WHICH ARE DESIGNED TO PREVENT THE RADAR FROM BEING ENGAGED BY $& LOCATION TECHNIQUES AND ASSOCIATED WEAPONS  4HE DEPLOYMENT OF A RADAR NETWORK WITH OVERLAP 
 235–248. 101. G. 
  
 In Proceedings of the 2014 IEEE Geoscience and Remote Sensing Symposium, Quebec City, QC, Canada, 13–18 July 2014; pp. 358–361. 3. 
 ENCE  EFFICIENCY  AND THE ELECTRICAL PROPERTIES OF THE SCATTERERS OF INTEREST )N ADDITION u (& RADAR WAVEFORMS MUST FIT WITHIN AVAILABLE CLEAR CHANNELS IN THE (& FREQUENCY  BAND  COMPLYING WITH STRINGENT CONSTRAINTS ON LEAKAGE INTO CHANNELS OCCUPIED BY OTHER USERS u 4HEY MUST BE COMPATIBLE WITH THE FACT THAT THE RADAR IS OPERATI NG IN A hWAVEGUIDE v  NAMELY THE VOLUME BETWEEN THE %ARTHS SURFACE AND THE IONOSPHERE  WITH UNIQUE POSSIBILITIES FOR MULTIPLE PROPAGATION PATHS INCLUDING ROUND 
 TheearlyCWwave-interference radarswereusefulonlyfordetecting thepresence ofthe target.Theproblem ofextracting target-position information fromsuchradarswasadifficult oneandcouldnotbereadilysolvedwiththetechniques existingatthattime.Aproposal was madebyNRLin1933toemployachainoftransmitting andreceiving stationsalongalineto beguarded. forthepurpose ofobtaining someknowledge ofdistance andvelocity. Thiswas. 
 eachtunedtoa diflcrent frequency. provides coverage oftheelevation sectorwiththeequivalent ofparallel rl:ceiving. beams.Theelevation angleofthetargetisdetermined bywhichreceiver isexcited. 
 1633. This line isthermally lagged by thebox ofFig. 16.35. 
  
 the other is for a sample size of 25.000 which represents a larger area  and includes a smaller density of point targets than the smaller sample. (From Daley, et af.31) . 496 INTRODUCTION TO RADAR SYSTEMS  effectiveness of interclutter visibility has been exploited in MTI radar and in non-MTI radar  with log-FTC receiver characteristics. 
 62,   pp. 1661–1701, December 1974.  8. 
  
 346–357, 1985. 36. G. 
 The gonio control was turned until maximum  reception of the echo was achieved (readily shown by  the period when the depth of the received blip was at its  greatest), when, if the gonio control were suitably en-  graved in degrees corresponding to aerial-array positions  in space, the true line of shoot could be determined. In  many such systems the gonio was elementary, consisting  of aerial arrays at right angles feeding into coils similarly  placed in the gonio. The first stage of the radar receiver  was fed from a pick-up coil which could be rotated by  the gonio knob over the facing aerial coils. 
 This was recog- nized fairly early by Hansen1 and Varian2 and others. In fact, the history of CW . radar shows a continuous attempt to devise ingenious methods to achieve the de- sired sensitivity in spite of spillover. 
 The Geometric Model and Signal Model of ArcSAR Figure 1shows the geometric model of ArcSAR system. The antenna of ArcSAR mounted by the boom rotates counterclockwise. It transmits and receives signals at equal intervals. 
  " "  (AMMING 
 Mk. VI Narrow Band Width Receiver, Air/Sea Warfare Development Unit (A.S.W. D.U.) Report No. 
 86.Shelton, J.P.,andK.S.Kelleher: Multiple BeamsfromLinearArrays,IRETraIlS.,vol.AP-9. pp.154-161, March, 1961. 87.Delaney. 
 In reality, the adaptive MTI would move FIGURE 2.86  Open-loop adaptive MTI for cancellation of simultaneous fixed and moving clutter ch02.indd   82 12/20/07   1:46:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar. 
 I., and D. G. Tucker: Discussion on " Detection of Pulse Signals in Noise: Trace-to-Trace  Correlation in Visual Displays," J. 
 Metal space-frame radomes can  be of large size, 150-ft diameter being quite practical. Designs up to 500-ft diameter have been  considered. The cross section of metallic members can be smaller than that of dielectric  members of equivalent strength; hence, the effect of aperture blocking is less. 
 TO 
 The result is a significant improvement in sea  scatter predictions, emphasizing the importance of breaking in the scattering scene.  An example of this improvement is shown in Figure 15.20, where experimental data  for the polarization ratio  relative to wind direction was obtained from the Polrad96  program.107 One of the major claims for Bragg models has been their apparent abil - ity to agree loosely with the observed polarization ratios of sea clutter returns, and  in Figure 15.20, as in Figure 15.19, the data were compared to the predictions of the  SPM (pure) Bragg model and the two-scale model, while adding the two-scale-plus  model , which incorporates the effects of breaking waves. In this case, the Bragg  model and the two-scale model derived from it clearly fail to describe the observed  behavior of the polarization ratio, while the inclusion of breaking waves (full model)  provides a surprisingly faithful reproduction of the data, even at the high grazing  angle of 50°. 
 Doppler frequency calculation is the easiest way to find fading rates. To compute the signal amplitude returned with a particular range of doppler shifts, all signals having such shifts must be summed. This requires knowledge of the contours of constant doppler shift (isodops) on the scattering surface. 
 In tracking. the target range does not usually limit  the time resource since the range is known and the dwell interval can he adjusted accordingly.  The power transmitted by the radar will depend on the type of function it is to perform as well  as the target maximum range and possibly the past behavior or the target. 
 Other methods to avoid clutter saturation. The dynamic range of a radar display, whether PPI  or A-scope, is far less than the range of echo-signal amplitudes that can be expected from  clutter. It is necessary, therefore, to keep the large clutter echoes from saturating the display  and preventing the detection of wanted targets. 
 L. Clampitt, “S-Band amplifier chain,” Raytheon Company, Waltham. MA, presented at NATO  Conf. 
 /",Ê / 
 15  much as the grid voltage. The  normal cathode-follower has no resistance load in  the anode circuit, but, of course, such an arrangement  could be used, as in Fig. 16. 
 Its response is equivalent to a triple canceler consisting  of a cascade of three singledelay-line cancelers. (Note the potentially confusing nomenclature.  A cascade configuration of three delay line's, each connected as a single canceler, is called  a triple canceler, but when connected as a transversal filter it is called a jbur-pulse canceler.)  d The weights for a transversal filter with n delay lines that gives a response sinn n, T are the  coefficients of the expansion of (1 - x)", which are the binomial coefficients with alternating  signs :  Input - -  Delay Delay ...- Delay  T2 -  T3 -  , Delay  T~  r L -  Summer I  I Fipre dl 1 General form of a trans-  versal (or nonrecursive) filter for MTI  Output signal processing. 
 VI patterns with a cosec2pattern also shown. It can be seen that the Mk. VI pattern was much closer to the desired shape. 
  
 For effective radar operation, environmental parameters need to be deter- mined in real time; transmission-path information is generally derived from ad- junct vertical and oblique sounders as well as by using the radar itself as a sounder. An ionospheric electron-density model complex enough to enable ade- quate sounding interpretation is required. Ionospheric or transmission-path sta- tistical forecasts are necessary for radar design and for development of the model, not for real-time operation. 
   PP n   *ANUARY   2 % +ELL  h/N THE DERIVATION OF BISTATIC 2#3 FROM MONOSTATIC MEASUREMENTS v  0ROC )%%%   VOL   PP n  !UGUST   7 ) +OCK  h2ELATED EXPERIMENTS WITH SOUND WAVES AND ELECTROMAGNETIC WAVES v  0ROC )2%   VOL   PP n  *ULY     + - 3IEGEL ET AL  h2#3 CALCULATION OF SIMPLE SHAPESBISTATIC v #HAPTER  IN  -ETHODS OF 2ADAR  #ROSS 
 The  response of this filter as a function of frequency is the property of interest.  For a received waveform s(t) with a given ratio of signal energy E to noise energy NO (or  noise power per hertz of bandwidth), North 1 showed that the frequency-response function of  the linear, time-invariant filter which· maximizes the output peak-signal-to-mean-noise  (power) ratio for a fixed input signal-to-noise (energy) ratio is  H(J) = GaS*(J) exp ( -j2nft i) ( 10. l)  00  where S(J) = f s(t) exp (-j2nft) dt = voltage spectrum (Fourier transform) of input  -00  signal  S*(J) = complex conjugate of S(J)  t 1 = fixed value of time at which signal is observed to be maximum  Ga= constant equal to maximum filter gain (generally taken to be unity)  The noise that accompanies the signal is assumed to be stationary and to have a uniform  spectrum (white noise). 
 ETITION FREQUENCY SO THAT THE DESIRED NUMBER OF LOOKS IS COLLEC TED DURING THE SYNTHETIC  APERTURE LENGTH OF THE AZIMUTH BEAM PATTERN 4HE CHALLENGE IS TO CALIBRATE THE ANTENNA PATTERN SUCH THAT THE FRAMELETS FROM ALL BURSTS MAY BE COMBINED TO ASSEMBLE A CONTINU 
 GE-17, pp. 113–128, 1979. 86. 
 The phase of the 1-k Hz signals contaii1s the same information as the phase of the multiple  frcquc1cies.  1 ,e MRB 201 Tellurometer is capable of measuring distances from 200 to 250 km,  assuminr reasonable line of sight conditions, with an accuracy of ±0.5 m ± 3 x 10-6 d,  where dis the distance being measured. The transmitter power is 20(\ mW and the antenna is a  small paraboloid with crossed feeds to make the polarizations of the transmitted and received . 
 ENCES ON RADAR METEOROLOGY PRESENT MORE PRECISE EQUATIONS )N ADDITION TO DISTRIBUTED CLUTTER TARGETS  THERE ARE MANY TARGETS THAT APPEAR AS  POINTS  SUCH AS RADIO TOWERS  WATER TANKS  AND BUILDINGS 4HESE POINT TARGETS TYPICALLY HAVE A RADAR CROSS SECTION OF   TO  M WITH TYPICAL DENSITIES AS SHOWN LATER IN  &IGURE  4HIS GRAPH IS FROM "ILLINGSLEY AND THE ADDITIONAL POINTS INDICATED BY AN  ASTERISK ARE FROM 7ARD &IGURE A SHOWS A 00) DISPLAY OF ALL CLUTTER OBSERVED WITH A SURVEILLANCE RADAR WITH  A  BY  
 ELEMENT PHASE INCREMENTS  4XS  4YS  HAVE BEEN COMPUTED FOR A  GIVEN BEAM 
 The terrain is illuminated by sunlight, at least partially  diffused through the atmosphere. At the eye, each pixel subtends the same azimuth and  elevation angles. Thus, pixels farther from the eye are larger (coarser resolution), in  both downrange and crossrange, than pixels closer to the eye. 
 B. Jackson, Digital Filters and Signal Processing , 2nd Ed., Norwell, MA: Kluwer, 1989. 61. 
 The term wilf include waveforms whose “tops” and “bottoms” arenot completely flat. Insome applications only tbe timing ofone orboth wavefronts matters, the particular shape ofthe whole wave not being ofinterest; (a) Square wave oscillator (no external stimulus) {Trkwf ~ (b)Flip-flop ‘e’p””’’nnn—r I“-V-’Sinusoid (c)3quaring amplifier ‘es””’’J-Ll-L /Trigger#l ~ (d) Flopover Trlsser X2~ [’-n”J—uLr—u (Trigger I I I II (e)Scaleoftwo ~‘es””” _nll——r FIG.13.12.—Response ofvarious waveform generators. inothers theshape isalso important. 
 The receive beams require low azi - muth sidelobes. A conventional beamforming approach would incorporate an array  at the focal plane with a single beam  per feed; however, the associated phase  distortion due to displacement causes  poor azimuth sidelobes. To correct  this problem, the feed array is placed  forward of the azimuth focal point,  enabling compensation and sidelobe  improvements via use of multiple feeds  per beam with appropriate feed phasing  (Figure 12.31 a). 
 Lindner, J.: Binary Sequences Up to Length 40 with Best Possible Autocorrelation Function, Elec­ tronics Letters, vol. 11, no. 21, p. 
 Electronics Tech. Rept. 18 1, Sept. 
 Hannan, “The ultimate decay of mutual coupling in a planar array antenna,” IEEE Trans .,  vol. AP-14, pp. 246–248, March 1966. 
 For Pe= I and small errors. the normalized pattern, obtained from Eq. (8.24) by dividing  by the value of 1.t~(O, 0) 12, is  (8.25)  The second term of this expression indicates that the larger the number of elements, the  smaller will be the statistical sidelobe level. 
 The refocusing method has three advantages, the ﬁrst is that the computational burden is low, due to the smaller data size of the sub-image than the raw echo data. The second is the procedures of the inversion algorithm and image reconstruction are simple. The last is that the ISAR technique based on fast minimum entropy phase compensation has good image quality and computational efﬁciency. 
 These are the basic factors involved in the choice or design of a feed for a reflector antenna. Other considerations include operating bandwidth and whether the antenna is a single-beam, multibeam, or monopulse antenna. Rectangular (pyramidal) waveguide horns propagating the dominant TE01 mode are widely used because they meet the high power and other requirements, although in some cases circular waveguide feeds with conical flares propagating the TE11 mode have been used. 
 Observations42  indicate that the liquid-water concentration in clouds generally ranges from 1 to   2.5 g/m3, although Weickmann and Kampe43 have reported isolated instances of cumu - lus congestus clouds (high towering convective clouds that frequently produce heavy  precipitation) with water contents of 4.0 g/m3 in the upper levels. In ice clouds, the  water content rarely exceeds 0.5 and is often less than 0.1 g/m3. The attenuation due  to cloud droplets may be written  K = K1M (19.15) where K = attenuation, dB/km  K1 = attenuation coefficient, dB/(km ⋅ g/m3)  M = liquid-water content, g/m3  M ai iN = =∑4 33 1πρ (19.16) ch19.indd   7 12/20/07   5:37:51 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Ulaby, and W. H. Peake: Variability in the Measurement of Radar Backscatter,  IEEE Trans., vol. 
 Each of these has its advantages and disadvantages, which are discussed in Chap. 6. A trans­ mitter which consists of a stable· low-power oscillator followed by a power amplifier is  sometimes called MqPA, which stands for master-oscillator power amplifier. 
        %     ,% )'   $$*( )#% -"+!* "**. Ó°Óä  2!$!2 (!.$"//+  4HIS DEFINITION ASSUMES THAT CLUTTER IS DISTRIBUTED HOMOGENEOUSLY ACROSS MANY  RANGE CELLS )N THIS CASE  THE ABOVE DEFINITION IS EQUALLY VALID BEFORE AND AFTER PULSE  COMPRESSION !GAINST POINT CLUTTER THIS DEFINITION ONLY APPLIES AFTER PULSE COMPRESSION AND MAY RESULT IN A DIFFERENT VALUE OF THE IMPROVEMENT FACTOR  4HE REAL DIFFICULTY WITH  THIS DEFINITION IS  HOWEVER  THE LACK OF A PRECISE DEFINITION OF THE DOPPLER VELOCITY INTER 
 Anequation fortheline-type pulser iseasily obtained, byeliminating R. between theexpressions forload current and voltage, as~. = ~. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo.  GROUND ECHO  16.456x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 discrimination is not possible below about 5 GHz. 
 TION WINDOW OF  o  RANGE GATES "LANK  OR EMPTY  BINS OCCUR WHEN THE UNFOLDED RANGE  FALLS OUTSIDE A PARTICULAR COARSE BIN INTERVAL +EY ADVANTAGES TO THIS APPROACH ARE THE ABILITY TO CHANGE THE RANGE CORRELATION WINDOW DYNAMICALLY AND  PERFORM MOTION COM 
 J. Ince, and D. H. 
   PP n  3EPTEMBER    , 2 7YATT  h! RELAXATION METHOD FOR INTEGRAL INVERSION APPLIED TO (& RADAR MEASUREMENT OF THE  OCEAN WAVE DIRECTIONAL SPECTRUM v )NT * 2EMOTE 3ENS  VOL   PP n  !UGUST    9 (ISAKI  h.ONLINEAR INVERSION OF THE INTEGRAL EQUATION TO ESTIMATE OCEAN WAVE SPECTRA FROM (&  RADAR v 2ADIO 3CIENCE  VOL   PP n     . (ASHIMOTO AND - 4OKUDA  h! "AYESIAN APPROACH FOR ESTIMATION OF DIRECTIONAL WAVE SPECTRA  WITH (& RADAR v #OASTAL %NG *  VOL   PPn     $ % "ARRICK  h%XTRACTION OF WAVE PARAMETERS FROM MEASURED HF RADAR SEA 
 Operational radars are generally designed to detect Z values ranging from 10 to 60 dBZ, while re- search applications usually aim for the maximum dynamic range possible. In light of the above, operational radars often employ sensitivity time control (STC) to compensate for inverse r2 dependence, but research radars usually do not use STC owing to the attendant loss of sensitivity at short ranges. 23.3 DESIGNCONSIDERATIONS Three of the more significant factors that affect the design of meteorological ra- dars are attenuation, range-velocity ambiguities, and ground clutter. 
 MONOSTATIC4RUE MONOSTATIC1UASI 
 The receiver must be protected from damage caused by the high power of the  transmitter. This is the function of the duplexer. The duplexer also serves to channel the  returned echo signals to the receiver and not to the transmitter. 
 FORM HAS SEVERAL DISTINCT ADVANTAGES OVER ,&-  )T REQUIRES NO FREQUENCY DOMAIN  WEIGHTING FOR TIME SIDELOBE REDUCTION BECAUSE THE &- MODULATION OF THE WAVEFORM IS  DESIGNED TO PROVIDE THE DESIRED SPECTRUM SHAPE THAT YIELDS THE REQUIRED TIME SIDELOBE LEVEL 4HIS SHAPING IS ACCOMPLISHED BY INCREASING THE RATE OF CHANGE OF FREQUENCY MODULATION NEAR THE ENDS OF THE PULSE AND DECREASING IT NEAR THE CENTER 4HIS SERVES TO TAPER THE WAVEFORM SPECTRUM SO THAT THE MATCHED FILTER RESPONSE HAS REDUCED TIME SIDELOBES  4HUS  THE LOSS IN SIGNAL 
 ch20.indd   58 12/20/07   1:17:02 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 
 When this temperature represents the available-noise-power output of the entire receiving system, it is commonly called the system noise temperature or operat- ing noise temperature,17 and it is then used to calculate the system noise power and signal-to-noise ratio, as in Eqs. (2.4) to (2.6). The Referral Concept. 
 NewYork,1950. X.Sciamhi, A.F.:TheEffectoftheAperture Illumination ontheCircular Aperture Antenna Pallern Characteristics. I\ficro\\'al'e J.,vol.8,pp.79-84,August, 1965. 
 20.2) can be solved to predict the  radar’s performance, as treated in Section 20.13. This is the basic approach employed  within RADAR C,29,55,56 for instance. From the operational HF radar viewpoint, use  of these propagation models is limited to statistical studies of radar performance, not  real-time radar support applications such as coordinate registration because of the  poor fidelity of the assumed electron density distributions and the shortcomings of  geometric ray-tracing. 
 For a large number of parallel doppler  filters, hardware implementation can be simplified significantly through the use of  the FFT algorithm. The use of this algorithm constrains all filters in the filter bank to FIGURE 2.55  Doppler filter bank of 68 dB Chebyshev filters, CPI = 9 pulses FIGURE 2.56  SCR improvement of 68 dB Chebyshev doppler filter bank compared with   the optimum ch02.indd   55 12/20/07   1:45:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Knott, A. W. Reed, and P. 
 Solid-state devices are also  utilized. In a typical duplexer application the transmitter peak power might be a megawatt or  RECEIVERS, DISPLAYS, ANDDUPLEXERS 359 backofthetubephosphor, oritcanbeusedtophotograph thedisplaywithout interfering withtheoperator. TheCRTphosphordoublesasarloptical andanelectronic screentogive theoperator amixedpresentation viewedintheusualmanner fromthefront. 
 An examination of Figure 13.23 shows that peak phase-quantization  lobes are significant and attempts should be made to reduce them. Reduction of Peak Phase-Quantization Lobes.  Miller78 points out that peak quan - tization lobes can be reduced by decorrelating the phase-quantization errors. 
 The doppler frequency shift is widely used to separate moving targets from   stationary clutter, as discussed in Chapters 2 through 5. Such radars are known as MTI  (moving target indication), AMTI (airborne MTI), and pulse doppler. All modern air- traffic control radars, all important military ground-based and airborne air-surveillance  radars, and all military airborne fighter radars take advantage of the doppler effect. 
 http://saturn.jpl.nasa.gov/spacecraft/instruments-cassini-radar .cfm 7. http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1704.pdf#search =%22chandrayaan-1%20radar%22 8. http://lunar.gsfc.nasa.gov/missions/scandinst.html †  Periapsis  and apoapsis  are, respectively, the points along an elliptical orbit that are closest to and farthest from the  gravitational center of the system. 
  
 1000 Me/see (FM), ,.,.. (AM)... 3000 Mc/sec(F.M). 
 Ulaby, R. K. Moore, and A. 
 TEMPORAL ADAPTIVE PROCESSING FOR NON 
 Poleward of these systems  lay the mid-latitude westerly winds, and equatorward lay the tropical easterlies or the  trade winds. Within these high-pressure systems, large-scale subsidence of air causes  heating as the air undergoes compression. This leads to a layer of warm, dry air overlay - ing a cool, moist layer of air (often called the marine boundary layer ).FIGURE 26.6  Evaporation ductEvaporation duct height Evaporation duct Modified refractivityHeight ch26.indd   12 12/15/07   4:53:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 119. Johnson. C. 
 S 4HE PHASE OF THE SIGNAL ALTERNATES &)'52%     !MBIGUITY FUNCTION OF A SINE 
 D. K. Barton, “Radar equations for jamming and clutter,” in Supplement to IEEE Trans. 
 Aspect Entropy Extraction Method at the T arget Level Target discrimination and classiﬁcation are important applications of SAR. The capability of aspect entropy on target discrimination is shown in Section 2. The aspect entropy of the target must be extracted to enable it to have a broader range of application. 
 Shannon presented information entropy to describe the uncertainty of the information source [ 17]. Electromagnetism is the concept of polarization entropy, which quantifies the disorder of scattering [ 18]. Polarization entropy ranges from 0t o1 , which corresponds to zero scattering to perfect depolarizing. 
 M. Sturm and J. C. 
       
 Small Arrays. The element pattern is the best single indicator of impedance matching in a scanning array. One way of determining the element pattern is to build a small array. 
 Thehorizontal sweep always occurs onthetube face inone direction from theorigin. Inmany cases, this isalsotrue ofthevertical component. (Sometimes negative heights areinvolved when the radar isonanelevated site. 
 Wu, “Quadrature sampling with high dynamic range,” IEEE Trans. Aerospace  and Electronic Systems , vol. AES-18, no. 
 Because of their primary mission of detecting low-flying aircraft, they cannot elevate their antenna beam to eliminate the clutter. These consider- ations have led to the development of airborne MTI (AMTI)1"3 radar systems similar to those used in surface radars1'4"6 discussed in the preceding chapter. Airborne MTI radar systems have also been utilized to acquire and track tar- gets in interceptor fire control systems. 
 aaPP E )N GENERAL  THE ANGULAR SPECTRUM IS NON 
 (electromagnetic corn pat ibility), and ECCM (electronic counter-countermeasures) all  influence the type of transmitter selected and its method of operation. The choice of transmit-  ter also depends on whether the radar operates from fixed land sites, mobile land vehicles,  sliips, aircraft, or spacecraft. Other considerations include the size and weight, high-voltage  and X-ray protection. 
 QUALITY TRANSISTOR THAT CAN BE MADE WITH USEFUL GAIN BEYOND 7 BAND (IGHER MOBILITY AND ELECTRON VELOCITY CAN BE ENGINEERED BY INCREASING THE PERCENTAGE CONTENT OF INDIUM IN THE CHANNEL OF THE &%4 4HIS CAN BE ACCOMPLISHED UP TO A POINT  WHERE BEYOND APPROXIMATELY  INDIUM CONTENT  THE LATTICE STRAIN DIFFERENTIAL RESULTS IN DEGRADING PERFORMANCE AND RELIABILITY 4HESE TECHNIQUES CAN RESULT IN TRANSISTORS WITH BIGGER BANDGAP DIFFERENCES THAN OTHERWISE POSSIBLE FOR THE CHOSEN MATERIALS 4HE FABRICATION OF THESE TRANSISTORS EMPLOYS THE USE OF ADVANCED SEMICONDUCTOR PROCESSING SUCH AS -OLECULAR "EAM %PITAXY -"%  OR -OLECULAR /RGANIC #HEMICAL 6APOR $EPOSITION . 
 114, pp. 2516-2536, 1986. 75. 
 The frequency dependence indicated bythedataofRef.37isindependent ofthepolarization and oftheangleofincidence (atleastovertherangefrom8to30°). Measurements ofcrops40anddrytrees41indicate thataboveXband,aOvariesapproxi­ matelylinearwithfrequency, evenupto3.2-mm wavelength. Thefrequency dependence for concrete, asphalt, andcinderandgravelroadsvariesapproximately asthesquareofthe frequency.4o Effectofresolution. 
 lYavelength 1,25cIll,0.80bcalll, altitude 4000ft, radius lOnautlcal mi. 39”32’N. 76”13’W. 
 JAMMING POWER RATIO BY  THE FACTOR  'T'SL 
 19 Spurious output, in transmitters, 10.19 Spurious response of mixers, 6.11 to 6.13 SR-71 low cross section aircraft, 14.39 to 14.41 Stabi lity requirements in pulse doppler, 4.27 to 4.31 Stagger PRF design for MTI, 2.39 to 2.46 STALO, 6.3, 6.14 to 6.20 Standard atmosphere, 26.3 Stand-off jamming (SOJ), 24.43 to 24.44 Station keeping, airborne, 5.27 Stealth, 14.2, 14.36, 24.38 Stratiform rain, 19.26 Stretch pulse compression, 6.10, 6.22, 8.31 to 8.36 in SBR altimeter, 18.40 to 18.41 String, radar cross section of, 14.6 to 14.7 Strip map, 18.23 Stripmap SAR (or “strip” SAR), 17.3 to 17.4 Subarray adaptivity to ECM, 24.25 to 24.27 Subarrays, 13.43 to 13.44, 13.49 to 13.50 Subclutter visibility, in MTI, 2.22 Subrefraction, 26.6 Sudden ionospheric disturbance, 20.18 Sunspot number, 20.17 Superclutter visibility, 2.84 Superheterodyne, 6.1 Superrefraction, 26.7 Superresol ution, 24.30 to 24.31 Surface discontinuities, and radar cross section, 14.3 Surface ducts, 26.10 to 26.11 Surface traveling-wave echoes, 14.36, 14.38 Surface ace-wave absorbers, 14.38 Surface winds, and HF radar, 20.37 to 20.38 Surveillance radar, 1.5 Surveillance radar equation, 1.12 Synthesizer, digital, 25.20 to 25.22 Synthetic aperture radar (SAR) autofocus, 17.15 basic principle of 17.1 burst mode, 18.23 to 18.24 clutterlock, 17.15 comparison with optical imaging, 17.18 to 17.21 comparison with real-aperture radar, 17.9 to 17.10 crossrange resolution, 17.7 to 17.8 design issues for SBR, 18.16 to 18.24 doppler beam sharpening, 5.34 to 5.36, 5.37, 17.2, 17.3 early history of, 17.2 and ECCM, 24.48 to 24.51 fast-time processing, 17.6 focused, 17.3 to 17.5 foliage penetration, 17.33 to 17.34. and ground penetrating radar, 21.4, 21.13 height measurement with, 17.27 to 17.23 image quality, 17.16 to 17.21 interferometric (InSAR), 17.5, 17.23 to 17.24, 17.30 to 17.33 inverse (ISAR), 5.23 to 5.24, 5.31 to 5.33, 9.37, 17.5, 24.51 to 24.52 Joint STARS, 17.23 to 17.24 key aspects of, 17.10 to 17.15 key equations, 17.21 to 17.22 motion compensation in, 17.12 moving targets in, 17.23 to 17.27 multiplicative noise ratio, 17.17 to 17.18 point-spread function, 17. 16 polarimetric, 17.22 pulse repetition frequency requirements for, 17.13 to 17.15 range migration, 17.15 range resolution, 17.6 to 17.7 range and velocity contours, 17.10 to 17.12. 
 Color can be an "atterition-getter," arid can improve the accuracy of recognition.  In an M'I'I radar with a syr~tl~etic-video display that presents only moving targets, the clutter  that is rejected (tlie raw video) can be superimposed on the display by showing it in a  diffcrr~it color tIi;111 tlie sy~ithet ic-video targets. (The display of weather clutter is of importance  to Ilie air traflic cor~troller to avoid directing aircraft to areas of severe weather. 
 14, pp. 917–940, 1996. 24. 
 pp.279-283. 32.Andrews. G.A..Jr.:Optimal RadarDoppler Processors, NRLReport7727,NavalResearch Labora­ tory.Washington. 
 While much work has been conducted to derive land subsidence information in so many cities, the potential applications of subsidence information are rarely discussed. It is also important to explore the application of subsidence information to disaster prevention, urban planning and hydrological modeling. Author Contributions: Conceptualization, Y.Z.; Methodology, Y.Z.; Validation, W.S.; Formal Analysis, Y.Z. 
 TURE #OURTESY OF (AZELTINE )NC .   !)2"/2.% -4)  Î°ÓÎ ACTUAL DISPLACEMENT ALONG THE LINE 
 STEERING THE SPACECRAFT .OTE THAT THE RADARS 02& NEEDS TO BE ONLY ABOVE THE .YQUIST LIMIT SET BY THE ANTENNA BEAMWIDTH  NOT BY THE TOTAL SPAN OF DOPPLER FREQUENCIES COLLECTED 2ANGE RESOLUTION IS IMPROVED IN THE USUAL WAY  BY INCREASING THE RADARS BANDWIDTH  FOR WHICH THE 3TRETCH TECHNIQUE IS OFTEN HELPFUL ! VARIATION OF THIS MODE 3LIP3!2  IS TO DRAG THE ANTENNA FOOTPRINT RATHER THAN TO STARE AT ONE AREA  THUS TRADING POORER AZIMUTH RESOLUTION THAN A PURE 3POT3!2 WOULD DELIVER TO GAIN INCREASED AZIMUTHAL COVERAGE (OW FAR CAN THIS BE PUSHED  5NDER THE ASSUMPTION THAT A TARGETS SCATTERING IS  COHERENT OVER A FULL  n SECTOR  IT CAN BE SHOWN  THAT THE ULTIMATE AZIMUTH RESOLU 
 Radars also require more  power from their host spacecraft than passive systems. These and related consider - ations motivated the development of WindSat, a passive instrument that estimates  near-surface vector winds by Stokes parameter analysis of the microwave emissivity  from the ocean surface.126  WindSat is one of two instruments aboard the Coriolis  satel - lite, launched in 2003. The operational reliability of passive-vector wind data relative  to scatterometric measurements remains an open issue. 
 TERN HAS CONSTANT GAIN WITHIN THE ACTUAL  D" POINTS AND ZERO GAIN OUTSIDE  BUT THIS CLEARLY IS NOT AN ACCURATE DESCRIPTION )F LARGE TARGETS APPEAR IN THE LOCATIONS ILLUMI 
 A clutter map uses adaptive thresholding where the threshold is calculated from the return in the test cell on previous scans rather than from the surrounding reference cells on the same scan. This technique has FIG. 8.21 Modified generalized sign test processor. 
 0ULSE  3TAGGERING  7HEN PULSE 
 The duration of the resulting pulse is proportional to the length of the interdigital trans­ ducer. Amplitude shaping can be controlled by varying the overlap of the electrodes, as in  Fig. 11.18. 
 LECTED 4HE RADAR ANTENNA USES THE  M ( 
 It should be noted that the normal radar criteria for range resolution is less appropri - ate for the case of a weak target adjacent to a strong target, and there is no accepted  definition of resolution for the case of unequal size targets. Plan Resolution.  The plan ( plan is defined as a plane normal to the direction  of propagation) resolution of a GPR system is important when localized targets are  sought and when there is a need to distinguish between more than one at the same  depth. 
 Chen, L.; An, D.; Huang, X. Extended Autofocus Backprojection Algorithm for Low-Frequency SAR Imaging. IEEE Geosci. 
 AES-20, pp. 363–400, July 1984. 45. 
 Figure 6. Selected interferometric images and the average coherence map (the last picture, bottom right) of the area shown in Figure 3a. During processing, high coherence candidates were selected, based on a coherence threshold of 0.6. 
 12, McGraw-Hill Book Company, New York, 1949.  2. Kraus. 
 The principles of a parabolic reﬂector areillustrated in ﬁgure 1.15. Since the r-f energy is transmitted in a narrow beam, particularly narrow in its horizontal dimension, provision must be made for directing this beamtowards a target so that its range and bearing may be measured. Normally,this is accomplished through continuous rotation of the radar beam at a rateof about 10 to 20 revolutions per minute so that it will impinge upon anytargets which might be in its path. 
 P. D. L. 
 TO 
 Rain adds to the absorption and eliminates the regions of relatively low attenu­ ation. For example, a rain of about 5 mm/h increases the attenuation of the 94-GHz window  by almost an order of magnitude. Figure 14.15 shows that a rain of 0.25 mm/h would not  significantly increase the clear-air attenuation. 
 T   Figure 2. Target P and its imaging result on the reference plane. The inverse Fourier transform is performed on S(θ,f) at the range direction to obtain its time domain form, which can be expressed as: Sc(θ,tr)=sin c⎭parenleftBig Br⎭parenleftBig tr−2Rp/c⎭parenrightBig⎭parenrightBig exp⎭parenleftBigg −j4πfc cRp⎭parenrightBigg (8) 134. 
 MADE AIRBORNE TARGETS 4HE LAWS OF PHYSICS COMBINED WITH THE ENVIRONMENT MAKE  IT IMPOSSIBLE TO  DESIGN AN -4) SURVEILLANCE RADAR THAT DOES NOT HAVE COMPROMISES 4HE PROBLEMS ARE RELATED TO THE UNWANTED RETURNS FROM BIRDS  INSECTS  AUTOMOBILES  LONG 
 It was noted that the horizontal aerials should havegiven the best results with the coastal beacons while the vertical antennas should have given best results with IFF Mk. III and vertically polarised beacons, such as Eureka. The main results of the trials are given in table 6.3. 
 155.  9. Long, M. 
 20.25  Elevation Error Due to Surface Reflections  ........  20.33  Low-Angle Squinted-Beam Height Finding  .........  20.35  21. 
 Cavity bridges are superior for development work on state-of-the-art sources, especially those that are difficult or expensive to pro- duce in pairs, and in the measurement of high-power transmitters such as the Hawk illuminator. Compare curve / of Fig. 14.8, measured in the early 1960s, with curve P of the same figure, which is the measurement floor of typical com- mercial instrumentation. 
 The only source of heat for those regions would be back - ground starlight and energy from the Moon’s interior, so that the ambient temperature  would be no more than ∼75 K. As water-ice enters such a cold space from comets, it  accumulates. This process generally is accepted as an explanation of the radar-bright  response from Mercury’s polar craters, for example, as observed by Earth-based radar  telescopes. 
 STATE SURVEILLANCE RADAR v PRESENTED AT )%% )NTERNATIONAL  2ADAR #ONFERENCE  ,ONDON  /CTOBER . 
 41. Scholefield, P. H. 
  )NDIA   -OON  &ORERUNNER -INI 
 5, pp. 1481–1485, May 2000. 48. 
 For this reason, care must betaken inthe design and tuning ofthenetwork coupling thecrystal to thefirst grid aswell asinthechoice oftheoperating conditions and type of thefirst tube. Figure 1264 shows atypical input circuit, with the primary tuned to resonate with the crystal and mixer capacity atthe intermediate fre- quency, and with thesecondary tuned toresonate with theinput capacity ofthe tube and socket. The coils are usually fixed-tuned or“slug- tuned” 1inorder toavoid any extra capacity. 
 Fortunately, this value is usu- ally very close to the true noise bandwidth, although the exact relationship of the two bandwidths depends on the particular shape of the frequency-response curve (Ref. 16, p. 177). 
 If any pulse is greater than five times  the average, all information from that range-azimuth cell is discarded. A saturation detector  detects whether any of the 10 pulses within a processing interval saturates the A/D converter  and if it docs, the entire 10 pulses are discarded.  The output of the MTD is a hit report which contains the azimuth, range, and amplitude  of the target return as well as the filter number and pr[ On a particular scan, a large aircraft  might he reported from more than one doppler filter, from several coherent processing inter­ vals. 
 Remote Sens. 2015 ,53, 3460–3470. [ CrossRef ] 18. 
 HANDLING CAPABILITY  OPERAT 
 Thus antenna gain is always less than directivity except for ideal lossless anten- nas, in which case TJ = 1.0 and G = G0. Approximate Directivity—Beamwidth Relations. An approximate but useful relationship between directivity and antenna beamwidths (see Sec. 
 QUENCY TO THE AVERAGE 02& OF THE RADAR 4HE CANCELER CONFIGURATIONS SHOWN ARE NOT THE MOST GENERAL FEEDFORWARD  FEEDBACK  NETWORKS POSSIBLE 0AIRS OF DELAYS ARE REQUIRED TO LOCATE ZEROS AND POLES ELSEWHERE &)'52%  4HREE 
 When rotated, it alternately  provides inductive and capacitive loading of the cavities to raise and lower the fre - quency. Such a rotary-tuned magnetron can provide very fast tuning rates. For exam - ple, at a rotation rate of 1800 rpm, a magnetron with 10 cavities can tune across a band  300 times per second. 
 AES-21, pp. 70-78, January 1985. 102. 
 229–243,  May 1988. ch23.indd   35 12/20/07   2:21:55 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 (Copy- right 1947, McGraw-Hill Book Company}1}Frequency, GHz 0.41 1.12 2.89 4.80 9.375RCS, m2 0.033-2.33 0.098-0.997 0.140-1.05 0.368-1.88 0.495-1.22 . 8SO-FT RCS RANGE FIG. 11.16 Measured RCS of a one-fifteenth scale model Boeing 737 commercial jetliner at 10 GHz and vertical polarization. 
 A. Jones, “3 cm and 10 cm wavelength radiation backscatter from rain,” in 5th Weather  Radar Conf ., AMS, Boston, 1955, pp. 281–285. 
 CAL DIMENSION   AND ITS PROPAGATION AND SCATTERING CHARACTERISTICS  TO OBTAIN ACCURATE RAIN 
 PHASED ARRAY RADAR ANTENNAS  13.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 They occur at angles given by sin q = ± [m/(s/l)], where m is an integer. For the half  space given by −90° < q < +90°, there are 2 m′ grating lobes, where m′ is the largest  integer smaller than s/l. If s < l, grating-lobe maxima do not occur, and the value at  ±90° is cos (p s/l). 
 Inthis way the cross sections inTable 3.3were obtained. The procedure amounts toareplace- TABLE 3.3,—RADAR CROSS SECTION OFSHIPS ICross section, ft’ Type ofship[ 1>=1 OcmIA=3cm I Tanker. 24X103 Cruiser. 
 Ó{°ÎÓ  2!$!2 (!.$"//+  WILL BE EXPECTED TO OPERATE 4HE SO 
 The contribution ofthis effect toazimuth error would beabout 0.045°, which isnegligible fornormal surveillance and control. Inoperations requiring very precise control of aircraft this error would beappreciable, and ifitwere doubled bydecreasing the v,to200theresulting error might beahandicap. 2.Cancellation ofechoes from stationary objects byMT1 means is less effectively achieved asthe number ofpulses per scan onthe target (N”,.) decreases (Chap. 
 REFERENCES 1. Skolnik, M. L: "Introduction to Radar Systems," McGraw-Hill Book Company, New York, 1980. 
 Figure 4represents the three diagrams of the unwrapped phase of the reference function, the polynomial approximation, and the phase error. The reference function unwrapped phase estimated with the described procedure was selected in an interval of values in which the phase difference between subsequent samples is not larger than π. This choice allows to contain the aliasing effect due to the sampled phase history. 
 PULSE COMPRESSION RADAR  8.236x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 8 For the case where n = 2, the weighting function can be integrated to obtain the following  relationship between time and frequency31  t Tf Ba f B = + sin( / )2π   where a = (1 – k)/2(1 + k) (8.22) which is similar to the sine-based NLFM discussed earlier. This particular code is  called Phase from Nonlinear Frequency (PNL)31 and its autocorrelation function is  shown in Figure 8.22 for a 100-µs pulsewidth, 1-MHz bandwidth waveform with   a = 0.7 and fd = 0. The time sidelobe levels are seen to be below –32 dB. 
 FORMING THE BASIC DECOMPOSITION DESCRIBED ABOVE  AND CALIBRATING THE RECEIVER CHAIN FOR THE CURRENT WAVEFORM  THE SIGNAL PROCESSING STAGE MAY BE TASKED WITH A NUMBER OF SIGNAL CONDITIONING OPERATIONS 3IGNAL CONDITIONING HERE REFERS TO FILTERING AND SCALING PROCESSES AIMED AT REMOVING CONTAMINATION AND DISTORTION THAT  IF LEFT ON THE SIGNAL  WOULD DEGRADE THE RESULTS OF THE PRIMARY PROCESSING OPERATIONS  SUCH AS DOPPLER ANALY 
 DAY VARIABILITY IS PRESENTED IN &IGURE   WHICH OVER 
 WIDTH JITTER         !  PULSE AMPLITUDE  6         $!  INTERPULSE AMPLITUDE CHANGE4!",%  )NSTABILITY ,IMITATIONS.   -4) 2!$!2  Ó°ÇÎ 4HE RMS PULSE 
 Any use is subject to the Terms of Use as given at the website. Radar Cross Section.  RADAR CROSS SECTION  14.116x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 Complex Objects.  Objects such as insects, birds, airplanes, ships, and antennas  can be much more complex than those just discussed, either because of the multiplic - ity of scatterers on them or because of the complexity of their surface profiles and  dielectric constants. 
 Appropriate timing pulses provide range gating so the angle-tracking circuits and  AGC circuits look at only the short range interval, or time interval, when the desired  echo pulse is expected. The range tracking operation is performed by closed-loop  tracking similar to the angle tracker. Error in centering the range gate on the target  echo pulse is sensed, error voltages are generated, and circuitry is provided to respond  to the error voltage by causing the gate to move in a direction to recenter on the target  echo pulse. 
 PL PL SIN; SIN SIN  =PP 
 CESSING DIAGRAM FOR '-4 WEAPON DELIVERY IS SHOWN IN &IGURE  )N THIS CASE  THREE DIFFERENT CLASSES OF TARGET OR MISSILE ARE TRACKED ! SINGLE WAVEFORM MAY BE USED TO TRACK STATIONARY  ENDO 
 Mks. III and VI, C.C.D.U. Trial Report No. 
 The nose angle of the planform is nearly double that of the F-117, yet barely half  that of the B-2, so the planform nose angle seems to be a compromise between the two.  Note that the absence of a cockpit improves the stealthiness of the airframe. Indeed,  the engine inlet cowling replaces the cockpit, and even the lips of the inlet are broadly  serrated to reduce their contribution to the radar echo. 
 20, 1988. 60. Walker, B, C., and M. 
 Burlage: An Initialization Technique for Improved MTI Performance in  Phased Array Radars, Proc. IEEE, vol. 60, pp. 
 WAVE CAVITY MAGNETRON EARLY IN 7ORLD 7AR )) IN  BY THE 5NITED +INGDOM 5+  4HE INTRODUCTION OF THE MAGNETRON ALLOWED HIGH 
 200  Dolph-Chebyshev array, 257  Dome antenna. 329-330  Dpppler filter bank, MTD. 127  Doppler frequency shift, 68-69, 79-80  in FM-CW radar, 83  Doppler measurement accuracy. 
  "!   !#!%!  "  %#   !#!%       !   !!  $!      &)'52%   3).2 VERSUS THE *$O! FOR A REGULAR SUB 
 13. “Maritime navigation and radiocommunication equipment and systems—Digital interfaces,” IEC  61162 (series), International Electrotechnical Commission, Geneva. 14. 
 2.BritishPatent13,170,issuedtoChristian Hiilsmeyer, Sept.22,1904,entitled" Hertzian-wave Project­ ingandReceiving Apparatus Adapted toIndicate orGiveWarning ofthePresence ofaMetallic Body,SuchasaShiporaTrain,intheLineofProjection ofSuchWaves." 3.Marconi, S.G.:RadioTelegraphy, Proc.IRE,vol.10,no.4,p.237,1922. 4.Breit,G.,andM.A.Tuve:ATestoftheExistence oftheConducting Layer,Phys.Rev.,vol.28, pp.554-575, September, 1926. 5.Englund, C.R.,A.B.Crawford, andW.W.Mumford: SomeresultsofaStudyofUltra-short-wave Transmission Phenomena, Proc.IRE,vol.21,pp.475-492, March,1933. 
 One consequence of the larger antenna vertical dimension is the 75-km swath,  which is narrower than that of Seasat. J-ERS-1 was crippled by antenna and connec - tor problems, so that its sensitivity (noise-equivalent sigma-zero NEq s  0 ) was only  –14 dB, 6 dB shy of its –20 dB design. As a result, J-ERS-1 image products were far  noisier than those of Seasat, whose sensitivity was –23 dB. 
 To reduce the level of noise, coherent summation of multiple complex ISAR images obtained after multiple applications of the image reconstruction procedure is applied. The number of complex images’ sums mitigating the level of the additive white Gaussian noise is 10. The ISAR signal from the asteroid is modelled in accordance with the algorithm presented by the ﬂow chart in Figure 4. 
 POWER LOSSES OF THE PHASE SHIFTERS AT THE RADIATING ELEMENTS AND RAISES OVERALL EFFICIENCY !LSO  PEAK 2& POWER LEVELS AT ANY POINT ARE RELATIVELY LOW BECAUSE THE OUTPUTS ARE COMBINED ONLY IN SPACE &URTHERMORE  AMPLITUDE TAPERING CAN BE ACCOMPLISHED BY TURNING OFF OR ATTENUATING INDIVIDUAL ACTIVE ARRAY AMPLIFIERS &OR PHASED ARRAY SYSTEMS WITH MODEST  POWER LEVELS  THE SOLID 
 CLUTTER  WILL ADD A NONSTATIONARY INTERFERENCE COMPONENT TO THE IMAGE 4HE AUTHORS SHOW THE IMAGE DEGRADATION FROM HOT 
 TOR DEFINED FOR A SINGLE DOPPLER FILTER )N &IGURE   THE OPTIMUM AVERAGE  ) 3#2 HAS  BEEN COMPUTED FOR SEVERAL DIFFERENT VALUES OF THE #0) AS A FUNC TION OF THE NORMALIZED  SPECTRUM WIDTH 4HESE RESULTS MAY BE USED AS A POINT OF REFERENCE FOR PRACTICAL DOPPLER &)'52%   /PTIMUM SIGNAL 
 An improved composite surface model for the radar backscattering cross section of the ocean surface: 1. Theory of the model and optimization/validation by scatterometer data. J. 
 Means are now available for computing the important design parameters ofsuch pulse transformers. 1 Successful hard-tube pulsers have been made with power outputs up 1PuZseGenerators, Vol. 5,Chaps. 
 Yizengaw, E.; Dyson, P .L.; Essex, E.A.; Moldwin, M.B. Ionosphere dynamics over the southern hemisphere during the 31 March 2001 severe magnetic storm using multi-instrument measurement data. Ann. 
 For the case ofaGaussian antenna pattern, we obtain theequation To 1.66 K=T”(lo) Itisconvenient toanalyze thefluctuation into anamplitude part and aphase part. Todothis wecanresolve thevector rinto two components, one inthedirection ofR,theother atright angles toR.The rms value ofeach ofthese components isrO/@. Thus the rms fluctuation in amplitude isrO/@ and the rms fluctuation inphase isapproximately ro/(Rov@). 
 REAL 
 However, high-power traveling-wave tubes tend to oscillate  at reduced beam voltage. Therefore the tolerance on the TWT beam voltage must be tighter  with increasing bandwidth. 7 The protection requirements for traveling-wave tubes are similar . 
 ρrepresents the coherence of the SAR image pair. It is related to the SNR, which is [ 24]: ρ=1 1+SNR−1(33) With reference to Equations (31) and (33), the h–ρcurve can be obtained, as shown in Figure 12. U Figure 12. 
 QUENCY OF 8 BAND  RAIN CAN SOMETIMES BE A SERIOUS FACTOR IN RED UCING THE PERFORMANCE  OF 8 
 IEEE T rans. Geosci. Remote Sens. 
 With the Fourier transform of the e n- velope of the pulses, an envelope of the spectrum results in the frequency domain.  For a re c- tangular pulse the result is the sin x/x function in the frequency domain.  The linear spacing is  reciprocal to the period T. 
 These seriously impair the quality ofcancella-. 672 MOVING TARGET INDICATION [SEC.16.19 tion. This difficulty can beavoided byoperating atacarrier frequency that isfaroffcrystal resonance but still onthe flat part ofthe loaded characteristic. 
 The output of the subtractors is again a bipolar signal that contains moving tar - gets, system noise, and a small amount of clutter residue if the clutter cancellation  is not perfect. The magnitudes of the in-phase and quadrature signals are then com - puted ( )I Q2 2+  and converted to analog video in a digital-to-analog (D/A) con - verter for display on a PPI. The digital signal may also be sent to automatic target  detection circuitry. 
 This type, analogous tothe antireflection coatings applied tooptical lenses, will bereferred toas“interference absorbers. ”Inthe second kind, thematerial oftheabsorber issodesigned that noreflection takes place atthe front surface and the attenuation inthe layer extin- guishes the entering wave. Acontinuous gradation from one kind of absorber totheother exists. 
 PULSE CONSISTENCY  4HEY ALSO PROVIDE COST SAVINGS THAT RESULT FROM THE INHERENT RELIABILITY OF THESE SWITCH MODULES COMPARED TO CONVENTIONAL SWITCH TUBES  AND THE ELIMINATION OF NUMEROUS AUXILIARY COMPONENTS NEEDED FOR THE OPERATION OF SWITCH TUBES   ,OWER OPERATING COSTS AND SMALLER COOL 
 MeteoroL, vol. 8, pp. 376-383, 1969. 
 The shallow reflector is easier to support and  move mechanically since its center of gravity is closer to the vertex, but the feed must be  supported farther from the reflector. The farther from the reflector the feed is placed, the  narrower must be the primary-pattern beamwidth and the larger must be the feed. On the  other hand, it is difficult to obtain a feed with uniform phase over the wide angle necessary to  properly illuminate a reflector with smallf;'D. 
 95. Flock. W. 
 Into this compartment project the pulse transformer bushings and the magnetron cathode bushing. The interior detail isshown inFig. 1I.28. 
 &IX #&!2  DETECTORS v )%%% 4RANS  VOL !%3n  PP n  *ULY   3 , *OHNSTON  h2ADAR ELECTRONIC COUNTER 
 FREQUENCY AMPLITUDE NOISE CONSISTS OF  BOTH RANDOM NOISE AND PERIODIC MODULATION 4HE RANDOM NOISE IS LARGELY A RESULT OF THE VIBRATION AND MOVING PARTS OF THE AIRCRAFT PRODUCING A RELATIVELY FLAT NOISE SPEC 
 But the RCS of permeable (dielectric) bodies is  more complicated than this because energy can enter the body and rattle around inside  before coming back out. An example is the dielectric sphere whose RCS is plotted in  Figure 14.3. Because the dielectric material is slightly lossy, as indicated by the non - zero imaginary component of the index of refraction, the RCS of the sphere decays  gradually with increasing electrical size. 
 The level of power output from the devices depends upon whether the device is operated pulsed or CW but can range from 1 W CW at 80 GHz to approximately 20 W pulsed at 80 GHz.9 In addition to IMPATT diodes, transferred electron devices (more commonly named Gunn diodes) made from GaAs or InP can be used up to about 100 GHz. At the lower part of the millimeter-wave band, CW power levels up to 2 W with 15 percent efficiency and pulsed power levels up to 5 W with 20 percent efficiency have been reported. 5.3 SOLID-STATEMICROWAVEDESIGN The solution to the radar range equation for most applications invariably requires high peak and average radiated power from the antenna in order to ultimately maintain some minimum signal-to-noise ratio on receive. 
 (4) The probability PFT of detecting a false target produced by a jammer entering through the radar sidelobes. PFT is the probability of associating (w, v) with H1 when H2 is true; it is a function OfJNR1 the thresh- olds a and F, and the gain margin p. (5) The probability PTB of blanking a target received in the main beam. 
 53. P. R. 
 To detect temporal changes, we propose using unsupervised feature learning algorithms in conjunction with optical ﬂow algorithms that track the motion of objects across time in small regions of interest. The proposed framework for distinguishing between actual motion and misregistration can lead to more accurate and meaningful change detection and improve object extraction from an SAR AGI product. Keywords: SAR; 2CMV; change detection; optical ﬂow; k-means; K-SVD 1. 
 It is suitable for dynamic CS problem. It is proved that LS-CS-Residual can recover the signal better than CS [ 17]. The subaperture images of WASAR can be regarded as the SAR video. 
 Geosci. Remote. Sens. 
  AND 6 
 30-A to 30-H.  96. Trunk. 
 July, 1959.  65. Weil, H., M. 
 TER  SEA CLUTTER  AND INSECTS ECHOES TO ACCOMMODATE FLEXIBLE SCAN STRATEGIES AND  TO INCORPORATE IMPROVED DATA RESOLUTION IN RANGE AND AZIMUTH 4HESE PERFORMANCE ENHANCEMENTS ARE READILY ACHIEVED BY INSTALLING GREATER AND MORE FLEXIBLE SIGNAL AND DATA PROCESSING POWER 3EVERE 3TORM 7ARNING  /NE OF THE PRIMARY PURPOSES OF WEATHER RADARS IS TO  PROVIDE TIMELY WARNINGS OF SEVERE WEATHER PHENOMENA SUCH AS TORNADOES  DAMAGING WINDS  FLASH FLOODS  AND LANDFALLING HURRICANES !CCURATE LONG 
 PHASE  AND 1 QUADRATURE  ARE TRADITIONALLY USED TO INDICATE THE REAL  AND IMAGINARY PARTS OF COMPLEX TIME 
 ESA-fed reflector architectures are well suited for  such applications and are described in greater detail in Section 12.3. Three relevant exam - ples are (1) missile defense radar, (2) space-based radar, and (3) ground-based search and  track radar (1D azimuth electronic scanning suffices for some of these applications). Classification of Reflector Antennas. 
 BASED SYSTEM NEEDS TO BE MODIFIED  THE !3)#S NEED TO BE REDESIGNED  INCURRING SIGNIFICANT EXPENSE 4YPICALLY  THE USE OF !3)#S MAKES SENSE IF TENS OR HUNDREDS OF THOUSANDS OF UNITS ARE TO BE SOLD  SO THAT THE DEVELOPMENT COSTS CAN BE AMORTIZED OVER THE LIFE OF THE UNIT 4HIS IS RARELY THE CASE FOR RADAR SYSTEMS (OWEVER  MANY  !3)#S HAVE BEEN DEVEL 
 #/5.4%2-%!352%3   Ó{°È£  2 ! -ONZINGO AND 47 -ILLER   )NTRODUCTION TO !DAPTIVE !RRAYS   .EW 9ORK *OHN 7ILEY    3ONS    * (UDSON  !DAPTIVE !RRAY 0RINCIPLES  ,ONDON 0ETER 0EREGRINUS ,TD    2 .ITZBERG   !DAPTIVE 3IGNAL 0ROCESSING FOR 2ADAR  .ORWOOD  -! !RTECH (OUSE  )NC    ( $ 'RIFFITHS  h! FOUR 
 (2.24) gives the probability of a false alarm, denoted PI,.  The average time interval between crossings of the threshold by noise alone is defined as  the filse-alarm time 3, ,  IN Ta = lim --  N-+W N k=~  where & is the time between crossings of the threshold VT by the noise envelope, when the  slope of the crossing is positive. The false-alarm probability may also be defined as the ratio of  the duration of time the envelope is actually above the threshold to the total time it coirld have  been above the threshold, or  N -  24INTRODUCTION TORADAR SYSTEMS maybeconsidered envelope detectors. 
 209–214, 1954. 63. A. 
 Scholtz, and B. Levitt, “Low probability of intercept communications,”  Chapter 4 in Spread Spectrum Communications Handbook , New York: McGraw-Hill, 1994,   pp. 1031–1093. 
 D" BEAMWIDTH  ARE  4HE SPECIFICATIONS FOR THE ELLIPTIC FILTER FOR THE ABOVE PARAMETERS ARE NORMALIZED STOPBAND EDGE  R F4    PASSBAND EDGE  RF4    STOP 
 P. L.: The Effect of Random PRF Staggering on MTl Performance, IEEE 1975 Jnternatio11al  Radar Co11(ere11ce, pp. 73--78. 
 EAR  WITH THE 66 SIGNAL STRONGER THAN THE (( 4HE CROSS 
 Escort jamming  is another ECM  tactic in which the jamming platform accompanies the strike vehicles and jams radars  to protect the strike vehicles. Mutual-support , or cooperative , ECM involves the coordinated conduct of ECM  by combat elements against acquisition and weapon control radars. One advantage of  mutual-support jamming is the greater ERP available from a collection of platforms  in contrast with a single platform. 
 ING PROPERTIES OF THE PARTICLE 3PHERICAL WATER DROPLETS IN AIR  THAT ARE LARGE RELATIVE TO THE  WAVELENGTH SCATTER IN THE SO CALLED OPTICAL REGION DROPLETS ON THE ORDER OF THE SAME SIZE AS THE WAVELENGTH SCATTER IN THE SO CALLED RESONANT SCATTERING REGION AND DROPLETS SMALL RELATIVE TO THE WAVELENGTH SCATTER IN THE SO 
 R. Levy-Nathansohn and U. Naftaly, “Overview of the TECSAR satellite modes of operation,”  in Proceedings , 6th European Conference on Synthetic Aperture Radar , Dresden, Germany, VDE  Verlag, 2006. 
 FREE  ISOTROPIC ANTENNA  THE GAIN IS UNITY )N FREE SPACE  THE POWER DENSITY AT A LOSS 
 /\ decoy is a small aircraftlike vehicle made to appear to the radar as a realistic target. If  the decoy and the aircraft are made indistinguishable to the radar, the radar operator may be  deceived into thinking the decoy is hostile and commit a weapon to attack. If sufficient decoys  arc present, the defense system could be overloaded. 
 = radar wavelength.34 STC may be implemented in the IF  of the receiver, but it can also be incorporated at RF by inserting variable-attenuation micro­ wave diodes ahead of the receiver. A particular STC characteristic can be limited by changes in  clutter due to changes in ambient conditions (such as wind speed and direction, or by anoma­ lous propagation), and by the nonuniformity of clutter with azimuth. Clutter-CF AR  techniques that are" adaptive" do not have this limitation. 
 http://www.eohandbook.com/eohb05/pdfs/missions_alphabetical.pdf#search =%22China%20HJ-1C%   20satellite%20radar%22 23. http://directory.eoportal.org/pres_SARLupeConstellation.html 24.  http://industry.esa.int/ATTACHEMENTS/A112/nfm2005_04.pdf#search =%22Japan%20space%20radar%20IG S-R1%22 25. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 A general block diagram model applicable to any MTI filter is shown in Figure 2.31.  This model has been denoted the “Direct Form 2,” or the canonical form, in the terminol - ogy survey presented in Rabiner et al.21 It can be shown that an MTI filter as shown in Figure 2.31 can be divided into a  cascade of second order sections as shown in Figure 2.32. 
 This  reduced range capability is acceptable in many situations since the height measuremcnt is  \~sually of more significance at shorter rather than longer ranges.  Lobe recognition. A coarse indication of height sometimes can be obtained by recognizing the  fading of the echo signal as an aircraft target flies through the multipath lobes of the antenna  pattern. 
 Ifthegradient oftheindexofrefraction isstrongenoughfortheraysto. have the same curvature as tlie earth itself, it would be possible for initially horizontal rays to  bend around the surface of the earth. From Eq. 
 3.If/Ipulsesareintegrated, theintegration-improvement factorIj(11)=11£;(11)isfoundfrom Fig.2.24.Theparameters (SIN),and11£;(11)aresubstituted intotheradarequation (2.33) alongwithaav' (2.40) a>OTheintegration-improvement factorinFig.2.24isinsomecasesgreaterthanII,orin otherwords,theintegration efficiency factor£;(11)>1.Oneisnotgettingsomething for nothing, forinthosecasesinwhichtheintegration-improvement factorisgreaterthann,the signal-to-noise ratiorequired forn=1islargerthariforanonfluctuating target.Thesignal­ to-noise perpulsewillalwaysbelessthanthatofanidealpredetection integrator forreasonable valuesofPd'ItshouldalsobenotedthatthedatainFigs.2.23and2.24areessentially independent ofthefalse-alarm number, atleastovertherangeof106to1010. Thetwoprobability-density functions ofEqs.(2.39a)and(2.39b)thatdescribe the Swerling fluctuation modelsarespecialcasesofthechi-square distribution ofdegree2m.38The probability densityfunction is ( )111(1/Ia)m-1(1/Ia)pa= I - exp-- , (111-1).(Jayaay (Jay. It is also called the gamma distribution. 
 W.W.:RadarTechnology Applied toAirTrameControL·IEEE Trans..vol.COM-21. pp.591605.May.1973. 29.Sutherland. 
 The reference171 provides a comprehensive study  of anti-jamming spatial adaptive techniques including also the space/slow-time  anti-jamming filter with suitable image reconstruction algorithm. Results indi - cate that the slow-time STAP provides superior interference cancellation than  spatial-only filtering. SAR usually involves wideband processing, requiring for  adaptive nulling techniques, peculiar algorithms. 
 The earlier order for SCR.517B was retaine d as an insurance against the failure of ASG.1. 8.1.1.1 ASV Mk. V In a further change of policy in the UK, in view of the urgent requirement for long- range aircraft, it was decided to allocate Liberators to Coastal Command. 
    $ECEMBER   DECLASSIFIED   % / "RIGHAM  4HE &AST &OURIER 4RANSFORM  .EW 9ORK 0RENTICE (ALL    PP n  $ ,YNCH  ET AL  h,0)2 PHASE  REVIEW v (UGHES !IRCRAFT 2EPORT    UNCLASSIFIED REPORT * / 0EARSON  h-OVING TARGET EXPERIMENT AND ANALYSIS v (UGHES !IRCRAFT 2EPORT .O 0 
 Aluminum honeycomb withaluminum skininasandwich construction hasbeenemployed wherehighlyaccurate surfaces arerequired. Reflector surfaces mayalsobeformedfrom fiberglass andasbestos resinated laminates withthereflecting surfacemadeofembedded mesh ormetalspray.Plasticstructures havetheadvantage ofbeinglight,rigid,andcapableofbeing madewithhighlyaccurate surfaces. Theirthermal properties, however, requirecareindesign andconstruction. 
 Minimum signal definitions such as minimum- detectable-signal or minimum-discernable-signal have been used in the past; how - ever, these definitions have become less common due to the extensive use of digital  signal-processing techniques. Digital signal processing of the receiver output allows  the detection of signals well below the receiver noise floor and the minimum detect - able level depends on the nature of the processing performed. Signal-to-Noise Ratio (SNR). 
 For example, if the receiver connected to  the middle element in an antenna array were to fail, beamforming would be more seri - ously degraded than if the failure were to occur in a receiver connected to an element  at the end of the array. Automatic detection of such a failure and reallocation of an end  element receiver to the middle element of the array would minimize the degradation. 20.13 RADAR PERFORMANCE MODELING Modeling is an essential part of the radar design process and also as a means to predict  the performance of existing or proposed radars to which one does not expect access. 
 1020106. 33. Gao, F.; Liu, X.; Dong, J.; Zhong, G.; Jian, M. 
 These filters might be "optimum" in that they satisfy the specified criterion,  but the criterion might not be the best for satisfying MTI requirements. (Optimum is not a  synonym for best; it means the best under the given set of assumptions.) Maximizing the  signal-to-clbtter ratio over all doppler frequencies, which leads to the binomial weights and  sinn njd T filters, is not necessarily a pertinent criterion for design of an MTI filter since this  criterion is independent of the target signal  characteristic^.^-^ It would seem that the MTI  filter should be shaped to reject the clutter at d-c and around the prf and its harmonics, but  have a flat response over the region where no clutter is expected. That is, it would be desirable  to have the freedom to shape the filter response, just as with any conventional filter. 
 That is, its passband is much narrower than the  reciprocal of the input pulse width so that the output will be of much greater duration than the  input. The narrowband filter "smears" the input pulse since the impulse response is approxi­ mately the reciprocal of the filter bandwidth. This smearing destroys the range resolution. 
 STATE DEVICES AND MEMORY CHIPS HAVE LED TO PRECISION APERTURE PHASE CONTROL WITH CORREC 
 In the Fraun-  Ilofcr rcgiori. tlrc radiating source and the observation point are at a sufficiently large distance  frorri each otllcr so tliat the rays originating from the aperture may be considered parallel to  one anotlier at the target (observation point). Radar antennas operate in the Fraunhofer  region. 
 Performing this optimization can  be done using Munkres algorithm.58 Munkres algorithm is an exact solution of  the minimization problem but is rarely used because it is computationally slow. A  more computationally efficient exact solution is the Jonker, V olgenant, Castanon  (JVC) algorithm.59 The JVC is much more efficient for sparse assignment matrices  (which are likely for practical radar-tracking problems). Speed improvements of   30 to 1000 times have been reported. 
 If monopulse measurements are available on the  Alert detection, the Confirm beam can be centered on the detection to decrease beam - shape loss. The Confirm dwell is typically a HRWS waveform and only examines  doppler filters within a window centered about the filter of the Alert detection cue. The  Confirm dwell must produce a detection corresponding to the Alert detection in order  for a valid detection declaration. 
 4IME !DAPTIVE 0ROCESSING FOR 2ADAR  .ORWOOD  -! !RTECH (OUSE    6 # #HEN AND ( ,ING   4IME 
 With this pro- tection interruptions areextremely brief and cause little difficulty. 17.16. Relay System for Airborne Radar.-In the system just described, thescanner synchronization was rendered fairly simple bythe continuous scanning, and the problem ofobtaining adequate signal strength was simplified bytheuseofdkectional antennas. 
 Roche: Moving-Target-Indicator Recursive Radar Filter using  Bucket-Brigade Circuits, Electrottics Letters, vol. 9, no. 4, pp. 
 .- -- - - - - -. .-. - +-  Parabolic  reflect; -fi,-\ :--- :  Displaced  from oriqinol  porobolic -,-"''  contour -' \ Figure 7.24 Cosecant-squared antenna  produced by displacing the reflector  surface from the original parabolic  shape. 
 [ CrossRef ] 13. Wang, B.; Xu, S.H.; Wu, W.; Hu, P .; Chen, Z. Adaptive ISAR imaging of maneuvering targets based on a modiﬁed Fourier transform. 
 However, if the antenna sidelobes are not low, the  clutter that enths the radar via the sidelobes can limit the improvement factor, as mentioned  previously [Eq. (4.40)]. The effect of the sidelobe clutter must often be considered in the design  of the signal processor of an airborne pulse-doppler radar. 
 29. D. McQuiddy, R. 
 MENT IS LIKELY TO OCCUR -ANY WEATHER RADARS HAVE SUFFICIENT SENSITIVITY TO DETECT DISCONTINUITIES OF CLEAR AIR ECHOES IN THE LOWER  TO  KM OF THE ATMOSPHERE OUT TO  OR  KM 4HIS DETECTION OCCURS PRINCIPALLY IN THE SUMMER MONTHS WHEN THE BACKSCATTERING MECHANISM IS CAUSED BY INSECTS IN THE LOWER LEVELS OF THE ATMOSPHERIC BOUNDARY LAYER AND SOMETIMES MAY ALSO BE DUE TO "RAGG 
 but some variation can be tolerated so long as it is not  sufficient to produce uneven illumination oft he cathode-ray tube display or degradation of the  MTI.  REFERENCES  l. Sil\'er. 
 11.: Choosing the Number of Faces of a Phased-Array Antenna for Hemisphere Scan  Coverage. IEEE Trcr~l.~., VOI. AP-13, pp. 
 [ 16] used deep neural networks for SAR ship detection and get good results. Chen et al. [ 29] presented a method for classiﬁcation of 10 categories of SAR images, and showed application in ship target recognition. 
 #/5.4%2-%!352%3   Ó{°Ó 4HE FIRST CONFIGURATION IS REGULAR WITH TWO ELEMENTS FOR EACH SUB 
 This device generates a binary pseudorandom code of zeros and ones of length  2" - 1, where 11 is the number of stages in the shift register. Feedback is provided by taking the  output of the shift register and adding it, modulo two, to the output from one of the previous  stages of the shift register. In the example of Fig. 
 .A/2+3 A/2+1 A/2 special maximum-minimum-circuit selecting a clutter-representative Sr from the A sum-values S1 , .  . , SA. 
 Air Force web site.20 The C-29 is a military version of the Raytheon Hawker 800XP  mid-size business jet. The Air Force web site reveals very little technical detail about the test conditions  attending the data collection, such as the frequency and polarization of the measure - ments, not even the units in which the RCS data are displayed. However, even if we do  not know the test frequency or polarization, we do know that the full-scale RCS will  be 10 log (3 × 3) = 9.5 dB higher than those charted in the figure (i.e., higher by the  square of the inverse scale factor). 
 Ionospheric effects on synthetic aperture radar imaging at 100 MHz to 2 GHz. Radio Sci. 1999 ,34, 257–268. 
 The ballistic missile early-warning system (BMEWS) radar develop- ment was in similar danger until a second (backup) tube development contract was placed that used integral vacuum cavities rather than external cavities for the high-average-power klystron development.1 Even a "successful" RF tube devel- opment may end up with a design that is marginal in arcing rate and/or in cooling design, leading to reliability problems, excessive maintenance and logistics costs, and an unhappy customer. As a result of the risks of pushing RF tube developments to (or unwittingly beyond) the state of the art, and especially if the desired power is known to be beyond the capabilities of a single tube, it becomes attractive to use more than a single RF tube and to combine their RF outputs; this turns out to be a very prac- tical approach, as will be discussed later (Sec. 4.5). 
 POLARIZED JAMMING IN THIS CASE ATTACKS A DESIGN DEFICIENCY IN THE RADAR 4HE REQUIREMENT FOR GOOD CROSS 
 The principle of the Cassegrain antenna is shown in Fig. 7.11. It is a two-reflector system  with the larger (primary) reflector having a parabolic contour and a (secondary) subreflector  with a hyperbolic contour. 
 With the same criterion asbefore wetherefore should have (5) Foral-psec pulse this gives Aj, <~Me/see. However, since most ofthe effect isconcentrated near theends ofthepulse, amuch larger variation isprobably permissible. Since the frequency pattern within the pulse does notchange from pulse topulse, thequality ofthecancellation isnot affected. 
 TION OF THE VERTICAL PLANE CONTAINING THE BORESIGHT WITH THE GROUND 4HE CORRESPONDING  DOPPLER FREQUENCY  WHEN @  IS A FEW BEAMWIDTHS FROM GROUND TRACK  IS  F66 DXX y LQLQSIN   4HIS PHENOMENON RESULTS IN A PLATFORM 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 6.30  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 situation, the distortions can result in severely degraded radar performance, and the  distortion of operating conditions can persist for some time after the signal disap - pears. 
 Of course, the  enemy did attempt to jam, and arising from our counter-  measures is some information which may later be of great  use in civil aviation over territory where atmospherics  and local bad reception conditions make Gee working  difficult. |  One of the most successful anti-jamming devices was  the XF. Under this stratagem a new transmission on a  frequency different from that being used comes up  suddenly, synchronized with the preceding transmission. 
 87-93, January.  1953.  43. 
 The characteristics of clutter will  be described as well as the various methods for reducing their harmful effects when they  interfere with the detection of desired targets.  Echoes from the )and or the sea are known as surface clutter, and echoes from rain or  other atmospheric phenomena are known as volume clutter. Because of its distributed nature,  the measure of the backscattering echo from such clutter is generally given in terms of a  470 . 
 Ciabattoni, G. Picardi, R. Seu, W. 
 Rudduck, M. C. Liang, W. 
 45. Final Report—Spaceborne Radar Study, Grumman Aerospace Corporation, AFSC- ESD contract F19628-74-/?-0140, Kept. 74-2UF-I, June 28, 1974. 
 C. Blanchard, “Raindrop size distribution in Hawaiian rains,” J. Meteorol. 
 The radar designer usually prefers to display theresults intheform ofacoverage diagram, which shows contours ofconstant field strength plotted incoordinates contrived toshow directly the effect ofthe curvature ofthe earth. One such contour, shown in Fig. 2.14, iscalculated foranomnidirectional antenna transmitting at 2600 Me/see from aheight of120 ftabove atotally reflecting earth. 
 Lisman, and C. Winn,  “The SeaWinds scatterometer instrument,” in Proceedings, IEEE International Geoscience and  Remote Sensing Symposium , Pasadena, CA, pp. 1511–1515, 1994. 
 Scott, “Flight to radar-map Earth from space,” Aviation Week and Space Technology ,   pp. 50−53, September 20, 1999 (Cover Story). ch17.indd   36 12/17/07   6:50:14 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 BAND NOMENCLATURE  AS SUMMARIZED IN 4ABLE  #OMMENTS  ON  THE  TABLE   4HE )NTERNATIONAL 4ELECOMMUNICATIONS 5NION )45   ASSIGNS SPECIFIC PORTIONS OF THE ELECTROMAGNETIC SPECTRUM FOR RADIOLOCATION RADAR  USE AS SHOWN IN THE THIRD COLUMN  WHICH APPLIES TO )45 2EGION  THAT INCLUDES .ORTH  AND 3OUTH !MERICA 3LIGHT DIFFERENCES OCCUR IN THE OTHER TWO )45 2EGIONS 4HUS AN  , 
 E 20- 10-Wooded hillS 10knotsWooded hillsSeaecho 40knots ChaffRain 10 1·0 010'--__ ..L.-_.L.--'--'-...J....-.1-.J---'-L -'-----"'----'----...J....-..J-..JL.......l-..L...L __ ---'_--'-_.L.--l--LJ.....L...L..J 0001 0"11==rmsvelocity spread tm/s Figure4.30Plotofdouble-canceler clutterimprovement factor[Eq.(4.26)]asafunction of(Tv=rms velocity spreadoftheclutter.Parameter istheproductofthepulserepetition frequency (fp)andthe radarwavelength (..1.).. chaff, however, as well as sea echo, can have a nonzero mean velocity4' which must be  properly accounted for when designing MTI signal processors.  The frequency dependence of the clutter spectrum as given by Eqs. 
 With advances in digital technology, it has become possible and practical to generate  waveforms directly at IF or RF carrier frequencies on a single integrated circuit chip. This  technique is called Direct Digital Synthesis , or DDS, and involves generating waveforms at  FIGURE   8. 26 Digital waveform generation block diagram ch08.indd   28 12/20/07   12:50:43 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 POLARIZED ASPECT  IS TO PROVIDE A CIRCULAR POLARIZATION TRACKING CAPABILITY #OUPLING A LINEARLY POLARIZED SIGNAL TO A CIRCULARLY POLARIZED ANTENNA RESULTS IN A  D" SIGNAL LOSS  BUT IT IS INDEPEN 
 During the dry season, on the otherhand,conditionsaredifferent.Ductingthenistherule,nottheexception,andonsome occasions extremely long ranges (up to 1,500 miles) have been observedon fixed targets. When the southwest monsoon begins early in June, ducting disappears on the Indian side of the Arabian Sea. Along the western coasts, however,conditions favoring ducting may still linger. 
 The Monte-Carlo simulation has a good agreement with the theoretical analysis that the imaging quality degenerates with the increase of scintillation strength and spectral index. The positive ISLR happens in the case of CkL≥1033and p≥4 due to the 196. Sensors 2019 ,19, 2161 serious expand of the azimuth mainlobe. 
 There  were only relatively few Italian-produced radars operationally deployed by the time they left  the war in September, 1943. The work in Japan was also slow but received impetus from  disclosures by their German allies in 1940 and from the capture of United States pulse radars  in the Philippines early in 1942. The development of radar in the Soviet Union was quite  similar to the experience elsewhere: By the summer of 1941 they had deployed operationally a  number of 80-MHz air-search radars for the defense· of Moscow against the German  invasion.14 Their indigenous efforts were interrupted by the course of the war. 
 The presummer output is resampled at a lower rate, fS, consistent with  acceptable filter aliasing. Then, range pulse compression is performed, assuming the  transmitted pulse is very long compared to the range swath. If chirp (linear FM) is used,  part of the “stretch” pulse compression processing is performed in the range compres - sion function with the remainder performed in polar format processing. 
 D. Blair, “Practical aspects of multisensor tracking,” in Multitarget-Multisensor  Tracking: Applications and Advances , V ol. III, Boston: Artech House, 2000. 
 Parabolic  reflector  ·· ·-·· . .(.·Hyperbolic  ___ \ ,ubrefl ec !or  _ __,' // ...  (a) Parabola--,  neol focul  point \  I \  \  I  I \  I RADAR ANTENNAS 241  \  \  \  \  I  I  I (\ fl;perbolo  ; f\Virtuol  focal  / point  (b)  Figure 7.11 (a) Cassegrain antenna showing the hyperbolic subreflector and the feed at the vertex of the  main parabolic reflector; (h) geometry of the Cassegrain antenna. 
 BAND 3!2 v IN  0ROCEEDINGS OF THE  )%%% .ATIONAL 2ADAR #ONFERENCE     PP   $ . (ELD  7 % "ROWN  AND 4 7 -ILLER  h0RELIMINARY RESULTS FROM THE .!3!*0, MULTIFRE 
 In 1943 there were three varieties of Mk. I and three varieties of Mk. II, as shown in table 6.1. 
 (Photograph courtesy of Raytheon Com- pany.} age to 8 nmi and a lOO-jxs nonlinear chirp pulse that provides coverage to 80 nmi. The 100-jxs pulse is compressed to 1 JJLS such that high duty cycle is achieved without compromising range resolution. The transmitter consists of 14 modules, each capable of 2000-W power output, that are combined to produce the greater than 25-kW peak level. 
 Arilenna Elements  1R 4L 3R 2L 2R 3L 4R 1L  Figure 8.28 Eight-element Butler bearn-forming matrix.  IIII'Fll'CllHlNICAl.l.Y SIFI'RI'I> "liASI'D ARRAY ANTENNA INRADAR.113 aphascdistrihlJlion tllatproduces aheam.10010tileleftoftilearraynormal. Thusthis simpletwo-element arraywilhasingle3-uBcouplerproduces Iwoinuependent beams. 
 116. ('hampine. G. 
 Keystone transform-based space-variant range migration correction for airborne forward-looking scanning radar. Electron. Lett. 
 ambiguous in both range and doppler. The radar platform is moving to the right at 1000 kn with a dive angle of 10°. The narrow annuli define the ground area that contributes to clutter in the selected range gate. 
 295 9.15 SCI Height Finder.. .298 9.16 Other Types ofElectrical Scanners. : 302 THE STABILIZATION PROBLEM. 
 11. Rihaczek, A. W.:·" Principles of High-Resolution Radar," McGraw-Hill Book Company, New York,  1969. 
 34!4% 42!.3-)44%23   ££°Ó OF A &%4 IS DELINEATED BY ANY OF SEVERAL PATTERNING TECHNIQUES ON A SEMI 
 Furthermore,  its intensity (power) is exponentially distributed.80,81 Because all the particles within  the sample volume are moving with some mean or average radial velocity, there is  a mean frequency of the doppler spectrum that is shifted from the transmitted fre - quency. Finally, since the particles are in motion with respect to one another, there is  also a doppler spread, often referred to as the width of the doppler spectrum. Zrnic  describes a straightforward technique of synthesizing digital weather radar signals  from a parameterized doppler spectrum characterizing a specific pulse volume.82  Doviak and Zrnic23 as well as Bringi and Chandrasekar24 give detailed derivations of  these relationships, whereas Keeler and Passarelli79 summarize distributed target data  characteristics and relate them to the sampled data sets representative of weather radar  and other atmospheric sounding systems. 
 Curlander et al.4 provide a detailed discussion of  several key options for SAR processing beyond simple image formation. ● Clutterlock  (Curlander et al.,4 Chapter 5) refers to the use of information in the  received signals to ascertain the center frequency of the echoes from the ground  (clutter) and compensate for sideways drift of the platform. ● Autofocus  (Curlander et al.,4 Chapter 5) describes the use of information in the  (complex) image itself to estimate and correct phase errors, and then reprocess and  sharpen the image (see also Carrara et al.3). 
 Having to start over is not unusual during a  new design effort. One cannot devise a unique set of guidelines for performing the design of a radar.  If that were possible, radar design could be done entirely by computer. 
 A tl~resl~old voltage VT/$;12 = 2.5 is shown. The crosshatched  area to the right of I~,/$:'~ under the curve for signal-plus-noise represents the probability of  detection. while the double-crosshatched area under the curve for noise alone represents the  probability of a false alarm. 
 Examples of PBRs operating with cooperative broadcast transmitters in the co-site  region are the Manastash Ridge Radar  operating with an FM broadcast transmitter for  tropospheric soundings,2,48 Silent Sentry  operating with FM and TV broadcast trans - mitters,49,50 and the HDTV-Based Passive Radar  operating with a high definition-TV  broadcast transmitter,51 the latter two configured for air surveillance. Examples of  PBRs operating with cooperative communications transmitters in the receiver- and  transmitter-centered regions are bistatic radars for planetary exploration. They use  a data link transmitter on the probe vehicle in the transmitter-centered region and an  Earth-based command transmitter in the receiver-centered region.2,52 The term cooperative transmitter is somewhat of a misnomer. 
 Based on Eq. (34), theideal antenna pattern is G(o)=GOCSC28. (35) Amore exact expression, based onEq. 
 For details of the construction and a discussion of the results, see the first edi- tion (1970) of the handbook or Ref. 12. Stabilization of Power Oscillators. 
 1383-1390, November,  1972.  60. See sec. 
 GRAPHIC PHENOMENA  FOR WHICH IT WAS MANEUVERED INTO AN EXACT REPEAT ORBIT PERIOD  DAYS   'EOSATS GEO 
 Brit. IRE, vol. 17, pp. 
       
 This is because  the single-delay canceler requires the best match between the actual pattern and the  required pattern near boresight, whereas double cancellation requires the best match  ch03.indd   16 12/15/07   6:03:17 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 
 L — Fm.12.5.-—Triode input circuit.The loading issoheavy that the interstage bandwidth isvery great. Since the value ofL2isthus non- critical, thecircuit is,infact, fixed- tuned. Inductance Laisani-f choke ofalmost any characteris- tics. 
 OTHER RADAR TOPICS 537  PROCESSED SIGNAL  KLYSTRON KLYSTRON  TRANSMlrtlR  REMOTE UNl T w  Figure 14.9 diock diagran~ of the ASR-8 airport surveillance radar. APG is the azimuth puise generator  which provides antenna timing information, and CJB is the cable junction box. (Courtesy o/ Texas  111.~f rlltt1~~11~s. 
 [ CrossRef ] 19. Shan, Z.; Wang, C.; Zhang, H.; An, W. Improved four-component model-based target decomposition for polarimetric SAR data. 
 RATED AND PROVIDES A CONSTANT OUTPUT POWER LEVEL REGARDLESS OF SMALL DEVIATIONS ON THE INPUT  )NSTABILITIES DUE TO 0- OF  WHICH &- IS A SPECIAL CASE   TEND TO DOMINATE THOSE  DUE TO !- !S SUCH  THE FOCUS WILL BE ON PHASE DISTURBANCES RANDOM PHASE NOISE AND DISCRETE SINUSOIDAL SIGNALS SPURIOUS SIGNALS  2ANDOM 0HASE .OISE  2ANDOM PHASE NOISE RIDING ON A LARGE SIGNAL CAN MASK  WEAK TARGET RETURNS 4HE OBJECT IS TO SPECIFY SYSTEM PHASE NOISE SO THAT IT IS WELL BELOW THE THERMAL NOISE WHEN A LARGE SIGNAL AT THE !$ SATURATION LEVEL IS PRESENT IN THE RECEIVER ! SIGNAL AT !$ SATURATION IS THE LARGEST SIGNAL THAT CAN BE LINEARLY PROCESSED BY THE RADAR RECEIVER  4HEN THE RADAR SENSITIVITY IS LIMITED BY THERMAL NOISE ALWAYS PRESENT  PLUS A SMALL INCREASE IN THE TOTAL NOISE LEVEL CAUSED BY THE PHASE NOISE 4HE PHASE NOISE OF OSCILLATORS AND OTHER COMPONENTS IS TYPICALLY SPECIFIED AS THE  MULTIPLICATIVE NOISE THAT RIDES ON A CONTINUOUS WAVEFORM  OR #7 PHASE NOISE )N PULSE DOPPLER RADAR  TRANSMIT GATING INTERRUPTS THE CONTINUOUS WAVEFORM TO PRODUCE A PULSED WAVEFORM  'ATED PHASE NOISE IS THE RESULT OF GATING #7 PHASE NOISE 4HE SPECTRUM OF  A PULSED GATED  SIGNAL IS DIFFERENT FROM #7 4HE RESULTING NOI SE  THE GATED NOISE  CAN  BE MUCH DIFFERENT FROM THE #7 NOISE  ESPECIALLY FOR LOW DUTY CYCLE WAVEFORMS AND NOISE CLOSE TO THE CARRIER )T IS PREFERABLE TO MAKE NOISE MEASUREMENTS ON EQUIPMENT .   05,3% $/00,%2 2!$!2   {°Ó UNDER THE SAME GATING CONDITIONS THAT  WILL BE USED IN THE RADAR SYSTEM 3OME DEVICES   SUCH AS HIGH POWER TRANSMITTERS  CANNOT OPERATE CONTINUOUSLY AND ONLY GATED NOISE  MEASUREMENTS ARE POSSIBLE 4HE GATED PHASE NOISE SPECTRUM IS THE SUMMATION OF THE #7 PHASE NOISE SPECTRUM REPLICAS CENTERED AT FREQUENCIES  o NF 2  WHERE F2 IS THE 02&  AND N IS AN INTEGER 4HE TOTAL GATED PHASE NOISE IN THE 02& BANDWIDTH  F2 EQUALS THE TOTAL  #7 PHASE NOISE IN THE TRANSMIT PULSE BANDWIDTH )N TERMS OF STABILITY REQUIREMENTS  THE SYSTEM REQUIREMENTS ARE DERIVED USING GATED PHASE NOISE  WHICH IN TURN IS CONVERTED TO A #7 VALUE FOR SPECIFYING COMPONENTS SUCH AS OSCILLATORS 4HE #7 PHASE NOISE FLOOR IS SMALLER BY A FACTOR OF THE RATIO OF THE 02& TO THE TRANSMIT BANDWIDTH WHEN THE #7 PHASE NOISE IS ASSUMED TO BE WHITE 3ENSITIVITY LOSS DUE TO PHASE NOISE IS QUANTIFIED BY THE INCREASE IN THE SYSTEM NOISE  FLOOR IN THE hCLUTTER 
 For reflector antennas, most losses occur in the transmission line leading to the feed and can be made less than 1 dB. By comparing Eqs. (6.2) and (6.3) with (6.4), the relation between gain and directivity is simply G = T]G0 (6.5) . 
 A 1 ° beam scanned 60 °, for example, requires a  time delay of 6 bits, the largest being 32 wavelengths, as well as an additional phase  shifter. The tolerances are tight, amounting in this case to a few degrees out of about  20,000 and are difficult to meet. Problems may be due to leakage past the switch, to  a difference in insertion loss between the alternate paths, to small mismatches at the  various junctions, to variations in temperature, or to the dispersive characteristics of  some of the components. 
 Basu, “An improved model of equatorial  scintillation,” Radio Science, 30,  607–617, 1995. 59. A. 
 Spatially variant apodization for squinted synthetic aperture radar images. IEEE T rans. Image Process. 
 F. Landry: A High-Power Coaxial Ferrite Phase Shifter, IRE  Trans, vol. MTT-9, p. 
 Huhnerfuss, W. Alpers, W. D. 
  
 The ECCM designer must minimize the amount of noise a jamma  can introduce into the radar receiver. It is difficult, however, to keep the noise out when the  Jammer is being illuminated by the main beam of the radar antenna. When this occurs, the  narrow sec!or in the direction of the jam mer will appear as a radial strobe on the rPI display. 
 This measurement can be of particular interest for echoes from the ground and the sea. Rough tar- gets scatter the incident electromagnetic energy diffusely; smooth targets scatter specularly. By observing the nature of the backscatter as a function of the inci- dent angle it should be possible to determine whether a surface is smooth or rough. 
 Since this type of switch hasgenerally been used with amodulated energy source, there is initially novoltage across A’Aand hence theimpedance ishigh from A’ toA.Asthevoltage isbuilt upthe current gradually increases until suddenly, and inaregenerative way, the impedance ofA‘Adrops, thereby allowing theline capacity toFIG. lC.43.—Rotary spark gap. discharge through the” switch,” lowering itsimpedafice still more. 
 LMSC- D384797, Jan. 20, 1975. 42. 
 Adam and M. A. Fischetti, “Star Wars. 
 Dashed curve, constant prf; solid curve, staggered  prf's. (From Zverev,22 Courtesy IEEE.) . MTI AND PULSE DOPPLER RADAR 117  the same weightings, but with 4 interpulse periods of -15 percent, -5 percent, + 5 percent,  and + 15 percent of the fixed period. 
 For a beam  scanned from broadside, each spectral component is steered to a slightly different direc - tion. To determine the composite effect of the components, it is necessary to add the  far-field patterns of all spectral components. This analysis has been performed80,81 and  it is apparent that the overall antenna gain of the pulse will be less than that of a single  spectral component that has maximum gain in the desired direction. 
 VI and to provide recommendations on the use of the Vixen attenuator. It was reported that the use of Vixen did make it very dif ﬁcult for a listening-receiver operator to determine if the radar was approaching. However, operating the Figure 4.31. 
 First, as in the MPRF case, all PRFs should be  clear at the maximum design range. Second, all PRFs should be clear to the maximum  doppler of interest. One possible selection criteria is given in Eq. 
 (5) Medium-frequency beacons, for use with a loop  aerial inside the aircraft. (6) Main beam-approach system,  injecting dots or dashes into the intercommunication system  to inform a pilot when he is to port or starboard of correct  course. (7), (8), and (12) High-frequency direction-finding aerials and very-high-frequency transmitter for use by Flymg  Control and for airfield signals. 
 LEVEL 34!0 ARCHITECTURE &OR A THREE 
 Organ-pipe scanner. Scanning tlie beat11 in tile parabolic torus is accomplished by moving a  sitigle feed or by switching tlie transmitter between many fixed feeds. A single moving feed may  he rotated about the center of tlie torus on an arm of length approximately one-half the radius  of tlie torus. 
  ,  2- = 2-   ,     , 2-   ,     
 Zebker, “Mapping small elevation changes over large areas:  Differential radar interferometry,” J. Geophys. Res. 
 Similarly, the noise intermodulation smears some of the signal energy outside the desired band. As a consequence, filtering after envelope detection is less efficient than filtering prior to detection. All postdetection circuitry should have several times the bandwidth of the echo, and predetection filtering should be optimized, as will be described. 
 SWEEP BASIS AND FOR EACH RANGE BIN ! TARGET ! IN THE MAIN BEAM WILL RESULT IN A LARGE SIGNAL IN THE MAIN RECEIVING CHANNEL AND A SMALL SIGNAL IN THE AUXILIARY RECEIVING CHANNEL ! PROPER BLANKING LOGIC ALLOWS THIS SIGNAL TO PASS 4ARGETS ANDOR JAMMERS * SITUATED IN THE SIDELOBES GIVE SMALL MAIN BUT LARGE AUXILIARY SIGNALS SO THAT THESE TARGETS ARE SUP 
 The 10 mile zero control on the switch unit would be used to keep a contact as near the edge of the PPI as possible on the 10 mile range. The tuning control on the indicator unit would be checked every ½ hour or so and set to give greatest sea return. In general, the 30/30 mile range setting would be used for searching, except for convoys and coastline detection, for which the 50/50 mile range was better. 
 More accurate  results must include the effects of latency between the Alert and Confirm dwells. Search detection performance is often characterized by the cumulative probabil - ity of detection, Pd,cum, which is defined as the probability that the radar will detect  a closing target at least once by the time the target has closed to a specified range.  Pd,cum is only defined for closing targets. 
 The first IGS-R was launched in 2003. The 2005 launch of a sequel failed. ERS-1 and ERS-2 . 
 Hence, they have  not been widely used in pulse compression radars. Polyphase Codes.  Waveforms consisting of more than two phases may also be  used. 
 Rott, “Retrieval of wet snow by means of multitemporal SAR data,” IEEE  Trans. on Geosc. and Remote Sensing , vol. 
 FIGURE 21.28  Sequence of unfocussed C-scans of a set of a buried AT mine targets at depth  increments of 10 mm ( Courtesy IEE ) ch21.indd   34 12/17/07   2:51:45 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 
 The maps of median values are accompanied by decile values to indicate  distributions over days of the season. (CCIR Report 322-3 (1988) has a significant  discrepancy, as pointed out by Sailors,108 so it should be used with caution.) These  noise maps provide the level that an omnidirectional antenna would receive. Even  though assuming isotropic CCIR noise has limitations, it does provide a reference  level for initial radar design. 
 corrlbine at port 4. None of the reflected energy appears at port 1. The difference in  patti lerigtll with ttte diode switches open and closed is 61. 
 ING IN A PAIR OF PENCIL BEAMS AT  n ( POLARIZATION  AND  n INCIDENCE 6 POLARIZATION   4HE ILLUMINATION GEOMETRY ALSO IS ADVANTAGEOUS BECAUSE THE INCIDENCE IS THE SAME FOR ALL ASPECT ANGLES 4HE BEAM 
 TRAILER TRUCK  AND A SURROGATE MOCKUP  OF A MISSILE  TRANSPORTER 
  Y   WHERE THE FIRST TERM ON THE RIGHT 
 Atmospheric absorption noise. It is known from the theory of blackbody radiation that any  body which absorbs energy radiates the same amount of energy that it absorbs, else certain  portions would increase in temperature and the temperature of other portions would  decrease.56 Therefore a lossy transmission line absorbs a certain amount of energy and rera­ diates it as noise. The same is true of the atmosphere since it also attenuates or absorbs  microwave energy. 
 45. D. Lynch, J. 
  
 4(% 
 FERENCE MITIGATION IN RADAR v  0ROC OF )%%%  )NT 2ADAR #ONF   !LEXANDRIA 6!   53!   -AY n    PP n  9 !BRAMOVICH  3 * !NDERSON  AND ! 9 'OROKOV  h3TOCHASTICALLY CONSTRAINED SPATIAL AND  SPATIO 
 FED REFLECTORS ARE GENERALLY AIMED CLOSE TO  BUT SLIGHTLY BEYOND  THE CENTER OF THE REFLECTOR AREA TO ACCOUNT FOR THE LARGER SPACE TAPER SPREADING LOSS  ON THE FAR SIDE OF THE REFLECTOR 4HIS GENERALLY RESULTS IN A SLIGHTLY UNSYMMETRICAL APERTURE ILLUMINATION 4HE CORNERS OF MOST PARABOLOIDAL REFLECTORS ARE FREQUENTLY ROUNDED NOT SHOWN   OR MITERED &IGURE D   TO REDUCE EXTRANEOUS SURFACE AREA ANDOR MINIMIZE THE  TORQUE REQUIRED TO TURN THE ANTENNA "ECAUSE THESE CORNER REGIONS ARE GENERALLY WEAKLY  &)'52%   'EOMETRICAL REPRESENTATION OF A PARABOLOIDAL REFLECTOR A   GEOMETRY AND B   OPERATION. £Ó°£n  2!$!2 (!.$"//+  ILLUMINATED BY THE FEED  THEIR REMOVAL GENERALLY HAS LITTLE IMPACT ON THE GAIN (OWEVER   CIRCULAR AND ELLIPTICAL OUTLINESRIMS WILL PRODUCE MODEST SIDELOBES IN BOTH PRINCIPAL AND NONPRINCIPAL PLANES )F VERY LOW SIDELOBES ARE SPECIFIED IN NONPRINCIPAL PLANES  IT MAY BE NECESSARY TO MAINTAIN SQUARE CORNERS  AS SHOWN IN THE UPPER PART OF &IGURE  E 0ARABOLIC 
 42  7.1.3 Range Measurement with CW Radar ........................................................................ 43  7.2 FM CW -Radar ................................................................................................................. 44  7.2.1 Range Measurement wit h FM CW Radar ................................................................. 
 Therefore, if the number of iterations is K, the computational complexity of the EMAM method can be written as: SEMAM =KScom. (19) The complexity of the main steps of the basic MAM method and the IMAM method are shown in Tables 2and 3, respectively. T able 2. 
 However, in  the example of airborne air-surveillance radars, AWACS is found at S band and the U.S.  Navy’s E2 AEW radar at UHF. In spite of such a difference in frequency, it has been said  that both radars have comparable performance.9 (This is an exception to the observation  about there being an optimum frequency band for each application.) The Nexrad weather radar operates at S band. 
 ;tnd S. J. P;II.SOIIS: -f'l~e H;itI;i~. 
 THETIC APERTURE  4HE TRADE 
 Raney, R. K.: Synthetic Aperture Imaging Radar and Moving Targets, IEEE 1·runs., vol. AES-7,  pp. 
 10. R. C. 
 BAND N 
 2.80) for substitution into the radar equation of Eq. (2.33).  THERADAR EQUATION 47 (!t:nsityfunction fortheClOSSsection cTisgivenbytiledensityfunction p(cT)=Iexp(_(J) a.v aa>'a20 (2.39a) \vilerecT.,istileaveragecrosssectionoveralltargetlluctuations. 
 CALLY OR ELIMINATED USING )& SAMPLING 4HIS  ALONG WITH THE REDUCTION OF HARDWARE REQUIRED  ARE THE REASONS THAT )& SAMPLING DESCRIBED IN 3ECTIONS  AND   IS BECOMING THE DOMINANT APPROACH È°£äÊ   "/" / Ê " 6 
 Skolnik. M. I., G. 
 TRACK FUSION SEE &IGURE   LOWER HALF  ASSOCIATES EACH DETECTION TO A  SINGLE RADAR TRACK STATE CALCULATED USING ONLY DETECTIONS FROM THAT RADAR 4HE SINGLE RADAR TRACK STATES ARE THEN GROUPED WITH EACH OTHER TO PRODUCE A NETTED TRACK STATE 4HE DESIGN DECISION AS TO WHICH APPROACH IS BETTER FOR GROUPING  DATA DEPENDS ON THE  RADARS AND TARGETS INVOLVED /NE CASE WHERE DETECTION 
 The strut is illuminated by a planar wavefront and one edge of the  scattering cone lies on the reflector axis (see Figure 12.13). If the strut tilts at 30° to  the axis, the scattering cone maximum angle is twice the tilt angle, or 60°. Thus, the  scattering from three struts forms intersecting rings, as shown in Figure 12.14. 
 Takingthelogarithm gives (10.36) Thisstatesthatforoptimum processing oneshouldtakethepulses,eachofamplitude VI n (wherei=I,2,...,,,),andsumthemaccording tothelawLInIo(avl)'Thissumis 1=1 compared withathreshold asgivenbytheright-hand sideofEq.(10.36). Therefore the combined detector andintegrator musthavealawgivenby y=InIo{av) (to.37). where y = output voltage of detector and integrator  a = amplitude of sine-wave signal divided by rms noise voltage  v = amplitude of IF voltage envelope divided by rms noise voltage  l,(x) = modified Bessel function of zero order  This equation specifies the form of the detector law which maximizes the likelihood ratio  for a fixed probability of false alarm. 
 Fung, D. Kaneko, G. J. 
 ING AND CENTROIDING ON THE TARGET RETURN WITH RANGE AMBIGUITIES BEING RESOLVED WITHIN THE TRACKER 2ANGE RATE IE  DOPPLER  MEASUREMENTS ARE FORMED WITH A CENTROID ON THE TARGETS DOPPLER RETURN IN THE FILTER BANK !NGLE MEASUREMENTS CAN BE OBTAINED USING MONOPULSE  SEQUENTIAL LOBING  OR CONICAL SCAN  WITH MONOPULSE BEING THE PROMINENT CHOICE IN MOD 
 On the negative side, utilizing an FPGA to its best advantage typically requires the  designer to have a thorough understanding of the resources available in the device.  This typically makes efficient FPGA-based systems harder to design than systems  based on general-purpose processors, where a detailed understanding of the proces - sor architecture is not necessarily required. Also, FPGA designs tend to be aimed at  a particular family of devices and take full advantage of the resources provided by  that family. 
 Stabilization istheuseofa servomechanism tocontroltheangularposition ofanantenna soastocompensate automati­ callyforchanges intheangularposition ofthevehiclecarrying theantenna. Anantenna not compensated fortheangularmotionoftheplatform willhavedegraded coverage. Onaship, forexample, anunstabilized antenna withitsbeamparalleltothedeckplanewillhaveits coverage shortened forsurfacetargetssincethebeamwillbelookingintothewaterorupin theairastheshiprollsorpitches.Inaddition todegraded coverage, themeasurement ofthe .angular position withanunstabilized antenna canbeinerrorunlessthetiltingoftheplatform isproperly takenintoaccount. 
 483-486, September/October, 1960.  39. Krason. 
 Some  radar outfits have a choice of several time-bases, the  ‘fast’ ones giving an open and more accurate reading  for near-by echoes. On the other hand, the maximum  range is limited mainly by two things: first, there is the  physical limit at which the apparatus will give any  sensible reception of an echo from a very distant object;  second, there is the limiting factor set up by the spacing  between the pulses, or, as we prefer to regard it, the  PRE. If we do not allow a sufficient space of time  between pulses for an echo to be received back from the  most distant range at which the outfit will work we shall  get a false set of readings. 
 IEE, vol. 93, pt. IIIA, pp. 
 261-276. 14. Long, W. 
 D. Zubakov, Extraction of Signals From Noise , New York: Dover, 1970. 20. 
 EARTH 
  &ANBEAMS # 66%3#!4 %23 
 INTERFERENCE PLUS NOISE POWER RATIO  3).2 ) IS MEASURED AT THE INPUT  OF A RECEIVING ELEMENT OF THE ARRAY AND REFERS TO ONE ECHO PULSE 4HE  )F REPRESENTS  THE PERFORMANCE OF THE ADAPTIVE ARRAY IT ACCOUNTS FOR THE TARGET SIGNAL INTEGRATION AND THE INTERFERENCE CANCELLATION 0RACTICAL APPLICATIONS OF TH E EQUATION ABOVE ARE  FOR  INSTANCE  IN #HAPTER  OF &ARINA  #RUCIAL FOR THE UNDERSTANDING OF THE ADAPTED ARRAY  PATTERN IS THE CONCEPT OF EIGENVALUE 
   &OR 3WERLING FLUCTUATING TARGET MODELS  THE  0D AND REQUIRED 3.2 CAN BE APPROXI 
  
 (ILL  )NC       PP n  - " 2INGEL  h4HE EFFECT OF LINEAR &- ON THE GROUND CLUTTER IN AN AIRBORNE PULSE DOPPLER RADAR v  IN .!%#/. g 2ECORD  VOL   $AYTON  /(  -AY n    PP n  & % .ATHANSON   2ADAR $ESIGN 0RINCIPLES   ND %D .EW 9ORK -C'RAW 
 J.Friis.H.T.,andC.B.Feldman: AMultiple' UnitSteerable Antenna forShort-Wave Receptil 1n.l3cll Sys.Tech.J..vol.16,pp.337-419, July,1937. 4.Skolnik, M.I.:SurveyofPhased ArrayAccomplishments andRequirements forNavyShips, "PhasedArrayAntennas," A.A.OlinerandG.H.Knittel(eds.),ArtechHouse,Inc..1972,pp.1520. 5.Ridenour. 
  ON MARINE RADAR BEACONS RACONS  v %DITION   )NTERNATIONAL !SSOCIATION  OF ,IGHTHOUSE !UTHORITIES )!,!   0ARIS     h4ECHNICAL PARAMETERS FOR RADAR BEACONS RACONS  v )45 2ECOMMENDATION - 
 • If a signal is present in a filter, the target's velocity range is known. fcf fc+fdAMP FREQUENCY  CHARACTERISTICNARROWBAND  DOPPLER FILTERS CROSSOVER  LEVELdB SCALE. 34Velocity Ambiguities ω ω ωcωc+ωdSpectrum of doppler  shifted CW signalCoherent pulse train spectrum  (fixed target -- no doppler)ωc ωc+ωdω ωcCENTRAL  LOBE  FILTERfdobserved=2vrλmod(PRF) fd=nPRF +fdapparentExpanded central lobe region with target doppler shift DOPPLER  SHIFTED  TARGET  RETURNS•T h e  s p e c t r u m is the Fourier transform of the pulse train waveform. 
 14.18  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 The distance r in Eq. 14.7 is measured from the surface patch dS to the point at  which the scattered fields are desired, which could be another surface patch. These  expressions state that if the total electric and magnetic field distributions are known  over a completely closed surface S (as indicated by the little circle on the integral  sign), the fields anywhere in space may be computed by summing (integrating) those  surface field distributions over the entire surface. 
 [ CrossRef ] 246. Sensors 2019 ,19, 3073 6. Berardino, P .; Fornaro, G.; Lanari, R.; Sansosti, E. 
 -During thewar, con- siderable effort wx expended inthe design ofradar forhighly precise position-finding onone target atatime. This tracking was ordinarily intended topermit the control offire against such atarget, but asthe war drew toaclose, itwas also used fordetailed control ofthemaneuvers ofthetarget byradio instructions from acontroller ataground station. This was done topermit blind bombing byfight-bombers too small to carry aradar setand itsoperator, ortoenable anairc#t notequipped with radar tomake ablind landing approach oninstructions from acon- troller ataground radar. 
 Dyer. F. B .. 
 This 5-amp change incurrent will 1See alsoMicrowave Magnetrons, Vol.6,Sec.7.2,Radiation Laboratory Series.. SEC. 10.6] MAQNETRON CHARACTERISTICS 353 produce afrequency modulation of5amp X0.4 Me/see per amp = 2Me/see. 
 Any use is subject to the Terms of Use as given at the website. Civil Marine Radar. 22.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 22 STC and thresholding is a process that is controlled in the digital domain but often  applies analog gain processes at RF and IF (at both pre- and post-log amplification) as  well as processes in the digital domain. Intimately connected with thresholding strate - gies are signal processing, such as FTC, pulse integration, and correlation processes,  both pulse-to-pulse and scan-to-scan. 
 0.: Mathematical Analysis of Random Noise, Bell System Tech. J., vol. 23, pp. 
 BEAM JAMMING WHERE ADAPTIVE BEAMFORMING IS SUPERIOR /N THE OTHER HAND  THE ADAPTIVE ARRAY ALLOWS ONE TO OBTAIN CERTAIN LOWERED SIDELOBES SIMULTANEOUSLY TO JAMMING NULLING #ONCERNING THE PRACTICAL APPLICABILITY OF ADAPTIVE ARRAYS SOME CONSIDERATIONS FOLLOW ! NUM 
 linear rather than square-law detectors are preferred. The radar shoi~ld he designed conserva-  tively with larger power and larger antenna apcrtirre than tile miriirni~n~ required for mirrginal  detection.  One of the better measures against many forms of ECM is an alert, Iiighly niotivatcd, well  trained, and experienced operator. 
 The oscillator itself must bedesigned with considerable care. The resonant circuit must have ahigh Q. Input and output loading must be held toaminimum. 
 Gurnett, and G. Picardi, “Detecting sub-glacial aquifers in the North  Polar layered deposits with Mars Express/MARSIS,” Geophysical Research Letters , vol. 32,   pp. 
 ballistic  missile defense (PAR, MSR), air defense (AN/SPY-I and Patriot), aircraft landing systems  (A N/TPN-19 and A N/TPS-32), mortar (AN/TPQ-36) and artillery (AN/TPQ-37) location.  tracking of ballistic missiles (Cobra Dane), and airborne bomber radar (EAR).  There have been many developmental array radars built in the United States, including  ESAR. 
 However, this estimate is some  3 dB lower than the peak amplitude attained in Figure 14.16 by the leading-edge  echoes 34º either side of nose-on incidence. Evidently there are other, more subtle  echo sources that contribute to the RCS at these aspects, possibly surface traveling- wave contributions. Approximate Methods. 
 The mean power is the lowest of any of the  modulation schemes and this is helpful in meeting regulatory requirements. The transmitted signal has noise-like characteristics and the received signal is  cross-correlated with a sample of the transmitted signal. The range of the target is  given by the time position of the cross-correlated signal and the amplitude by the peak  of the cross-correlated signal. 
 WAVE /4( RADAR SYSTEMS   THE IONOSPHERE ALSO PROPAGATES UNWANTED INTERFERENCE SIGNALS TO THE RADAR SITE  PAR 
 THEORETIC REPRESENTATION OF THE RADIOWAVE FIELD 2AY 
 Denenberg, R. J. Serafin, and L. 
 3  )NTL -ICROWAVE  3YMP  VOL @#( 
 110'. /05, "Radar-Present and Future," Oct. n 25. 
 12.3  Available Scattering Information  .........................  12.3  12.2 Parameters Affecting Ground Return   .....................  12.4  12.3 Theoretical Models and T heir Limitations   ............... 
 Ofcourse such adecrease invideo bandwidth isaccompanied byamarked deterio- ration inthe time discrimination, orresolution inrange,ofthe system unless therange resolution isalready limited byother factors. Because ofthis, and forother reasons aswell, designers have usually aimed at adequately wide video bands. Actually, theeffect ofvideo bandwidth narrowing would not deserve even this much discussion here, were itnot that, inaless obvious way, avery similar effect arises from certain other influences, having todo with the spotsizeand the sweep speed. 
 B. Crane, “Optimization of linear arrays for broadband signals,” IEEE Trans .,  vol. AP-14, pp. 
 .·,,;  Probability density function of sea .clutter. The amplitude of sea clutter is characterized by  statistical fluctuations which.must:be described.in terms of the probability density function.  When the echo from the sea can be. 
 62  8.8.2 Digital Pulse Com pression ........................................................................................ 66  8.8.3 Digital Pulse Compression with Barker Code .......................................................... 67  9 Beamforming ......................................................................................................................... 
 Reflector performance comparisons were made for titanium and graphite composite materials. Generally the tolerances that must be held on reflector antennas are more severe than for phased arrays for the same performance. Figure 22.4 shows the results of the analysis. 
  
 460 12.9 AGeneral-purpose Receiver. 462 12.10 Lightweight Airborne Receiver 464 12.11 AnExtremely Wide-band Receiver 470 CHAP. 13. 
 (The offset frequency is equal to  the doppler frequency shift associated with a scattcrer located at the edge of t llr: rcal ailtcnna  beam.) The result, which is similar to reconstrtlcting the image of a hologram, is that the  desired real image can then be separated from the energy associated with the bias and the  virtual image. The slit is displaced from the optical axis at the place where the offset frequency  focuses the real image. A recording film in the output plane P2, when moved with a speed  proportional to that of the vehicle carrying the radar, produces a map of the scene originally  viewed by the radar. 
 ANGLE TRACKING IS THAT THE TARGET AND ITS IMAGE ARE  ESSENTIALLY COHERENT AND THEIR RELATIVE PHASE CHANGES SLOWLY AND THE ANGULAR ERROR IT CAUSES IS READILY FOLLOWED BY AN ANGLE 
 Most ofthesystems described have seen some use, although afew that areincluded have been tried only briefly. SPECIFIC SYSTEMS 5.6. Simple Doppler System.—We describe first asystem capable of detecting one ormore moving objects inthepresence oflarge amounts of ground clutter. 
 DOPPLERS ARE NOT CLOSE TO ORTHOGONAL NEAR THE AIRCRAFT VELOCITY VECTOR SEE &IGURE   3!2  ON THE OTHER HAND  IS USUALLY FULLY MATCHED RELATIVE TO THE DESIRED RESOLUTION AND PHASE HISTORY  IN EVERY RANGE 
 C. Zelli, “ENVISAT RA-2 Advanced radar altimeter: Instrument design and pre-launch   performance assessment review,” Acta Astronautica , vol. 44, pp. 
 It can  limit the performance of an MTI radar if sufficient care is not taken in design, construction,  and maintenance.  Consider the effect of phase variations in an oscillator. If the echo from stationary clutter  on the first pulse is represented by A cos &t and from the second pulse is A cos (or + A4). 
 £°È  2!$!2 (!.$"//+  4RACKING RADAR 4HIS IS A RADAR THAT PROVIDES THE TRACK  OR TRAJECTORY  OF A TARGET  4RACKING RADARS CAN BE FURTHER DELINEATED AS 344  !$4  473  AND PHASED ARRAY  TRACKERS AS DESCRIBED BELOW 3INGLE 4ARGET 4RACKER 344   4RACKS A SINGLE TARGET AT A DATA RATE HIGH ENOUGH  TO PROVIDE ACCURATE TRACKING OF A MANEUVERING TARGET ! REVISIT TIME OF  S DATA RATE OF  MEASUREMENTS PER SECOND  MIGHT BE hTYPICALv )T MIGHT EMPLOY THE MONOPULSE TRACKING METHOD FOR ACCURATE TRACKING INFORMATION IN THE ANGLE COORDINATE !UTOMATIC DETECTION AND TRACKING !$4   4HIS IS TRACKING PERFORMED BY A SUR 
 CAL AIRCRAFT  WHERE AVAILABLE SPACE IS LIMITED  .EVERTHELESS   THEY ARE VERY EFFECTIVE IN  CAPTURING AND DECEIVING THE RANGE GATE WITH THE 2'0/ TECHNIQUE   THE VELOCITY GATE WITH THE 6'0/ TECHNIQUE   AND THE ANGLE 
 Hence fi divides the radiation pattern into a  uniforni sidelohc region straddling the main beam and a decreasing sidelobe region. The  number ofrkqual sidelobes on each side of the main beam is iI - 1.  l'lie bcarnwidtl~ of a Taylor pattern will be broader than that of tlie Dolph-Cllebysliev. 
 LOOP ADAPTIVE DIGITAL -4) . Ó°nÓ  2!$!2 (!.$"//+  7HEN DOPPLER SHIFTS ARE INTRODUCED BY DIGITAL MEANS AS DESCRIBED ABOVE  THE ACCU 
 TR 360-4, Lawrence, 1979. 114. F. 
 In March, 1936, the range of detection had increased to 90 miles and the frequency was  raised to 25 MHz.  A series of CH (Chain Homej radar stations at a frequency of 25 MHz were successfully  demonstrated in April, 1937. Most of the stations were operating by September, 1938, and  plotted the track of the aircraft which flew Neville Chamberlain, the British Prime Minister at  that time, to Munich to confer with Hitler and Mussolini. 
 23. Hoft, D. J.: Solid-State Transmit/Receive Module for the PAVE PAWS Phased Array Radar, Microwave J., pp. 
 :trltcrirln. Ever1 if the solid-state transtnitter were lighter than a conventional tube transmitter,  tllc weight is found at a bad place, on ttie antenna itself. This is especially important for  sllipbonrd application wllcre weight lligll on tlle rnast must be minimized. 
 ACTERIZATION IS DONE CAREFULLY AND GOOD MANUFACTURING TECHNIQUES CAN GUARANTEE TOLER 
  
 This is an intensity-modulated display in which the amplitude of  the receiver output modulates the electron-beam intensity (z axis) as the electron beam is made  to sweep outward from the center of the tube. The beam rotates in angle in response to the  antenna position. A B-scope display is similar to the PPI except that it utilizes rectangular,  rather than polar, coordinates to display range vs. 
  
 OF 
 Type b is center-fed and has almost the same bandwidths as a FIGURE 13.30  Optical-feed systems: ( a) lens array and ( b) reflectarray ch13.indd   47 12/17/07   2:41:00 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 When the function is performed by electronic  decision circuitry without the interventio11 of an operator, the process is known as mttomatic  detection. One of the chief reasons for employing automatic detection is to overcome the  limitations of an operator due to fatigue, boredom, and overload. In addition, the use of  automatic detection allows the radar output to be transmitted over telephone lines rather than  by more expensive broadband microwave links, since only detected target information need be  transmitted and not the full bandwidth signal (raw video). 
 (8.4)  is replaced by its argument, the half-power beamwidth is approximately equal to  The first sidelobe, for N sufficiently large, is 13.2 dB be1o.w the main beam. The pattern of a  uniformly illuminated array with elements spaced A12 apart is similar to the pattern produced  by ;I contirtuously il1urniri;tted urliforrii aperture [Eq. (7.16)J. 
 31 Angular dependence of the depolarization ratio of a  smooth surface ( after F . T. Ulaby, R. 
 Exceptfortheinclusion ofmeanstoextractthedoppler amplitude component, thenoncoher­ entMTiblockdiagram issimilartothatofaconventional pulseradar. Theadvantage ofthenoncoherent MTIisitssimplicity; henceitisattractive forthose applications wherespaceandweightarelimited. Itschieflimitation isthatthetargetmustbe inthepresence ofrelatively largecluttersignalsifmoving-target detection istotakeplace. 
 AES-12, pp. 287-290, March, 1976.  49. 
   PP n   !PRIL    * .EYMAN AND % 3 0EARSON  h/N THE PROBLEMS OF THE MOST EFFICIENT TESTS OF STATISTICAL HYPOTH 
 J.: Wind Torques on Rotating Radar Aerials, Marconi Rev., vol. 28, pp. 147-170, 2d qtr.. 
 On striking the diode, wliicti is reverse biased well helow tile  avalanche threshold, each impacting electron gives rise to thousands of additional carrier pairs  to provide a current amplification of 2000 or more. A control grid is inserted between the  cathode and the diode to density-modulate the electron beam. (The basic geometry is similar  to that of the classic triode vacuum tube, but with a semiconductor diode as the plate.)  The EBS can also be deflection-modulated by varying the position of the beam relative to two  or more separated semiconductor targets whose outputs are combined. 
 lVhen agiven indicator isswitched from upper-beam data tolower-beam data, the mechanism controlling angular orientation ofthe sweep must be suddenly shifted through alarge angle. Operationally, onthe other hand, this arrangement was aconsiderable convenience. Agiven air- craft could frequently beseen ineither beam, an”d byswitching beams every half-revolution ofthe antenna the operator could double the rate atwhich hereceived plots. 
 DRIVEN NONRECIPROCAL FERRITE PHASE SHIFTERS AND WAVEGUIDE 
 Measurement errors. The absolute accuracy of radar altimeters is usually of more importance  at low altitudes than at high altitudes. Errors of a few meters might not be of significance when  cruising at altitudes of 10 km, but are important if the altimeter is part of a blind landing  system. 
 344 INTRODUCTION TO RADAR SYSTEMS  reference signals are needed to properly extract target information. Spt!cific applications such  as MTI radar, tracking radar, or radars designed Jo m inimizc duller place spccia I denrnnds on  the receiver. Receivers that must operate with a transmitter whose frequency can drifl need  some means of automatic frequency control (AFC). 
 CONTROL RADAR +EEP IN MIND THAT THE OPERATING FREQUENCY  OF THE RADAR  ALONG WITH ITS REQUIRED RANGE AND RADIAL VELOCITY COVERAGE  DETERMINES WHETHER A 02& IS CONSIDERED MEDIUM  HIGH 
 The output of the  amplifier would then be independent of the range, for constant target cross section. Amplifier  response shaping is similar in function to sensitivity time control (STC) employed in conven-  tional pulse radar. However, in the altimeter, the echo signal from an extended target such as  the ground varies inversely as the square (rather than the fourth power) of the range, since the Doppler Switched  frequency  counter velocity ---+  3 fo(~i) Receiver  mixer f;F+~ amplifier  IF 4?dy]- det:c+or :T amplifier ' Low -frequency Balanced -  CWANDFREQUENCY-MODULATED RADAR85 Doppler velocity1 I I I I I I Switched frequency counter Average Range frequency -~ counterLow-frequency amplifierTirningsignal Local oscillatorModulator fa(t)+Iir foU) foU)-firr----'---, '---__-'~r+If,'---__ ....I (fb=:fa(t-T)-fa(t))0···fO!.j).. 
 Some point to the continued maturation of vacuum electronics3 and suggest that both  vacuum tubes and solid-state devices will be appealing in high performance radars for  many years to come. Others note still that the best value in electronic equipment is pro - vided when the “appropriate technology”4 is applied to affordable military electronics,  recognizing that tubes and solid state may remain as complementary design solutions Chapter 11 ch11.indd   1 12/17/07   2:25:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 NOISE RATIO MUST BE KNOWN FOR EACH FILTER WHERE TARGETS ARE TO BE DETECTED ! GENERAL MEASURE THAT CAN BE EASILY APPLIED TO SPECIFIC CLUTTER LEVELS IS THE IMPROVEMENT FACTOR  ) 7HEN USING A DOPPLER FILTER  BANK  AS OPPOSED TO AN -4)  FILTER  THE IMPROVEMENT FACTOR IS DEFINED FOR EACH DOPPLER FILTER AS THE RATIO OF THE SIGNAL 
 Wei, Z.; Zhang, B.; Wu, Y. Accurate Wide Angle SAR Imaging Based on LS-CS-Residual. Sensors 2019 ,19, 490. 
 20  Many phase-shifting devices are reciprocal in that the phase change does not depend on  the direction of propagation. Some important phase shifters, however, are nonreciprocal. These  must have different control settings for reception and transmission. 
 23. LeCun, Y.; Bottou, L.; Bengio, Y.; Haffner, P . Gradient-based learning applied to document recognition. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.28  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 13.5 LOW-SIDELOBE PHASED ARRAYS Low sidelobes have long been of interest to antenna designers. 
 Therefore thetheoryofFouriertransforms canbeappliedtothe calculation oftheradiation orfield-intensity patterns iftheaperture distribution isknown. TheFouriertransform ofafunctionf(t)isdefinedas F(f)=roof(t)exp(-j21lft)dt • -00 andtheinverseFouriertransform is f(t)=rooF(f)exp(j21£Ji)df • -00(7.12) (7.13) ThelimitsofEq.(7.10)canbeextended overtheinfiniteintervalfrom-00to+00sincethe aperture distribution iszerobeyondz=±a12. TheFourier transform permitstheaperture distribution A(z)tobefoundforagiven field-intensity patternE(¢),since (7.14) Thismaybeusedasabasisforsynthesizing anantenna pattern,thatis,findingtheaperture distribution A(z)whichyieldsadec;iredantenna patternE(4)). 
 (b) 0800 UTC is a nighttime example.Height (km)Height (km) . Frequency (MHz) (a) Frequency (MHz) (b) FIG. 24.10 Predicted ionograms as in Fig. 
 Theangular position ofthedipoleelements isrelatively unimporlanl.I13 Thefollowing conclusions applytothecontinuous antenna: 1.According toRuze,lll thespurious sidelobe radiation isproporlional tothemeansquare error,justasinthediscrete array,andinaddition isproportional tothesquareofthe correlationintervalmeasured inwavelengths. Bates114defineshiscorrelationintervaldif­ ferentlyfromRuzeandobtainsafirst-power dependence forthisreason. 2.Iferrorsareunavoidable inareflecting antennasurface.theyshouldbekeptsmallinextent'; thatis,forthesamemechanical tolerance, theantenna withthesmallercorrelation interval Figure8.30Plotof(Jbversus0/0"where (Jbistherms phaseerrorsuchthatthepointing errorwillheinthe interval(-0,0) withaprobability p(O)forarrayswith A/2spacing; solidcurvesapplyforp(O)=0.95;dashed 0.10curvesapplyforI'((J)=0.99;O.=angletothefirstl1ull; D=antenna length.(Courtesy HugJlesAircraftCo.)f:::/001.0 0.8- 0.4-. 
 Alves, B. Chapman, J. Cruz, Y . 
 TRACKING CIRCUITS ARE ALWAYS LOCKED ONTO THE REAL TARGET  4HE METHODOLOGY OF INTRODUCING 6'0/ INTO THE RADARS TRACKING CIRCUITS IS ANALOGOUS  TO THE METHOD USED WITH 2'0/ 4HE FREQUENCY SHIFT IS INITIALLY PROGRAMMED SO THAT THE REPEATED SIGNAL IS WITHIN THE PASSBAND OF THE DOPPLER FILTER CONTAINING THE TARGET RETURN 4HIS IS NEEDED TO CAPTURE THE DOPPLER FILTER CONTAINING THE TARGET  THROUGH THE RADARS !'# ACTION 4HE REPEATER JAMMER SIGNAL IS THEN FURTHER SHIFTED IN FREQUENCY TO THE MAXIMUM EXPECTED DOPPLER FREQUENCY OF THE RADAR 4HE REPEATED SIGNAL IS THEN SWITCHED OFF  FORCING  THE VICTIM RADAR TO REACQUIRE THE TARGET  #OHERENT TRACKING RADARS CAN CHECK THE RADIAL  VELOCITY DERIVED FROM DOPPLER MEASUREMENTS WITH THAT DERIVED FROM DIFFERENTIATED RANGE  DATA !NOMALOUS DIFFERENCES PROVIDE A WARNING OF THE PROBABLE PRESENCE OF A DECEPTION JAMMER 7HEN 2'0/ AND 6'0/ OPERATE SIMULTANEOUSLY  THE BEST DEFENSE IS THE CONTEM 
 21.1 Azimuth resolution for three cases: curve a, conventional; curve b, unfocused; curve c, focused. field pattern of an antenna. The beginning of the far field occurs at a distance *min for which *min ~Y (2L9) It will be noted by substitution of Eq. 
 /- 4HE RECEIVED POWER  0R FROM A RADAR POINT TARGET CAN BE DERIVED FROM ANY OF A VARIETY  OF EXPRESSIONS THAT ARE APPLICABLE TO RADAR IN GENERAL   &OR A SINGLE POINT TARGET  A  SIMPLE FORM THAT IS READILY DERIVED IS   0RR BS     WHERE A IS A CONSTANT DEPENDENT  UPON RADAR SYSTEM PARAMETERS TRANSMITTED POWER  0T   ANTENNA SYSTEM GAIN  '  AND WAVELENGTH  K   R IS THE RANGE TO THE POINT TARGET  AND  R IS  THE RADAR CROSS SECTION 2#3  )T IS IN THE CALCULATION OF  R FOR DISTRIBUTED METEOROLOGICAL TARGETS THAT THE RADAR  EQUATION DIFFERS FROM THAT FOR POINT TARGETS &OR DISTRIBUTED TARGETS LIKE RAINFALL THE 2#3  MAY BE WRITTEN   R   G6    WHERE G IS THE RADAR REFLECTIVITY IN UNITS OF  CROSS 
 ONLY CORRELATION  THE  0 &! PER RANGE 
  BLOCK 
 AES-4,  pp. 410–416, May 1968. 61. 
 Soc. Am., vol. 58, pp. 
 MERS CAN BE OBTAINED  THESE CAN BE EXPLOITED TO FORM BEAMS IN THE JAMMER DIRECTIONS  WHICH ARE USED AS AUXILIARY CHANNELS FOR ADAPTIVE INTERFERENCE SUPPRESSION  4HE  INTERFERENCE DIRECTIONS CAN ALSO BE USED FOR DETERMINISTIC NULLING  WHICH IS OF INTEREST FOR MAIN 
 Thesuper- position isusually accomplished byinterlacing thesweeps. sInsofarasthequestion ofdiscernibility canbestated interms oftheprobability ofsignal-plus-noise being larger than noise, thelawofthedetector, andindeed ofany subsequent elements, canbeeliminated from thetheoretical problem. Table 21,for example, holds foranydetector whose output isafunction oftheabsolute value ofthe i-fvoltage.. 
 MANCE  IS AT LEAST COMPARABLE TO OTHER WIND SCATS  WIND SPEED AND DIR ECTION ACCURACY  BEING  MS TO  MS AT  MS AND  n  RESPECTIVELY .OMINAL SURFACE RESOLUTION IS    KM ADVANCED PROCESSING REDUCES THIS TO  ^ KM !LTHOUGH THE SWATH IS  KM  WIDE  THE VARIETY OF ASPECT AND POLARIZATION COVERAGE LIMITS THE SCIENCE 
 13.5 LAND C1,UII'EH  pJ'lle cliriter frort~ land is geticrally more of a problem than the clutter from sea, both in tlieory  i1111i ill ~)~;~cticc. ~'IIc I~;Ic~sc;I~~cI. 1'10111 I;III~ is sigtiifi~i1tlt1~ gtratcr lllari from sea except it1 tllc  vicinity of near vertical incidence. 
 January. 1972.  27. 
 It is an example of a successful application of the principles of the adaptive antenna  that utilizes only a relatively few number of adaptive elements. The fully adaptive array of  large size is, in theory, capable of nulling a larger region of space than a system with but a  relatively few adaptive elements, as in the sidelobe canceler. However, the added complexity  and longer convergence time that accompanies the greater degrees of freedom of the large,  fully adaptive array has been a burden that is difficult to justify on a cost-effective basis for  general application. 
 STATE 0AVE 0AWS RADAR 4HE 6! 
 BEAM WIDTH THAT RESULTS FROM LOW SIDELOBES WORSENS THE PROBLEM OF MAIN 
 INSTRUMENTATION TRACKERS  30!352 FOR SPACE SURVEILLANCE   AND 3ANCTUARY FOR  AIR DEFENSE  4HE "27, FOR ARTILLERY  MORTAR  AND ROCKET LOCATION  THE 2USSIAN  3TRUNA 
 CAL AND MAGNETIC PROPERTIES OF THE GROUND AROUND AND IN FRONT OF THE ARRAY 4O ACHIEVE . Óä°ÓÈ  2!$!2 (!.$"//+  GAIN AT LOW 
 Stability is the inverse of this ratio; both are generally ex- pressed in decibels. In radars with phase-coded transmission and pulse compression receivers, residue may be significant in the range sidelobe region as well as in the com- pressed pulse, caused by phase modulation during the long transmitted pulse rather than solely from pulse to pulse. Measurement of stability of such radars must employ a very large number of data points to obtain an answer valid for clutter distributed in range. 
 Radar System Engineering  Contents  ii     8.1 The History of Pulse Radar ............................................................................................. 49  8.2 Transmission Types of Pul se Radar ................................................................................ 49  8.3 Simple Pulse Radar ......................................................................................................... 
 It is with some regret that 16 of the chapters in the original could not be included in this second edition. As in the first edition, no attempt was made to utilize a standard notation throughout the book. Each particular subspecialty of radar seems to have developed its own nomenclature, and it is not appropriate in a book such as this to force authors to use notation that is foreign to their field even though it might be commonplace in some other aspect of radar. 
 BAND  RADAR LOOKING UPWIND AT LOW  GRAZING ANGLES   6VIR       5 MS     !S NOTED EARLIER  CARE MUST BE TAKEN WHENEVER WIND SPEED IS USED TO PARAMETERIZE  A PROCESS THAT DEPENDS ON WAVEHEIGHT 4HERE IS AN UNAMBIGUOUS RELATION ONLY FOR A FULLY DEVELOPED SEA IN THE ABSENCE OF SWELL  4HE REMAINING PROPERTIES OF THE CLUTTER SPECTRUM CAN NOW BE DISCUSSED IN TERMS OF  6 ORB AND 6VIR  &OR EXAMPLE  THE SPECTRAL  PEAK FOR HORIZONTAL POLARIZATION FOLLOWS A SIMILAR LINEAR DEPENDENCE ON  5  ONLY WITH  A COEFFICIENT LYING SOMEWHERE BETWEEN  AND   AS MAY BE NOTED IN THE SKETCH SHOWN IN &IGURE  4HE REASONS FOR THE DIFFERENCES BETWEEN THE SPECTRA FOR THE TWO POLARIZATIONS ARE NOT AS YET CLEAR  ALTHOUGH THE TENDENCY OF THE ( 
 §©¶¸w 
 This topic is discussed in Sec. 21.5. Signal-to-Noise-Ratio Considerations. 
 Maggi: Modern Radar Data Display System: The Selenia IDM-7 Digital Display,  Ril'ista Tecnica Selenia (Rome, Italy), vol. 2, no. 4, pp. 
 2tU  V-bcam radar. 542  Varactor diode, 291  Variance. 21  Vdocity modulation. 
 T able 2. Comparison of coordinates of typical scattering points. Scattering Point 1 (x, y, z)Scattering Points 2 (x, y, z)Scattering Points 3 (x, y, z) Theoretical coordinate (0.0125, 0.2688, 0) (0.1438, 0.2438, 0) (0.1188, 0.1688, 0.0467) Traditional imaging (0, 0.24, 0.6438) (0.12, 0.23, 0.14) (0.1, 0.1, 0.13) Mixed sum norm (0.009, 0.26, 0) (0.1387, 0.24, 0.046) (0.11, 0.1, 0.046) Mixed inﬁnite norm (0.008, 0.26, 0) (0.1387, 0.24, 0.046) (0.1063, 0.1, 0.046) Mixed Euclidean (0.01, 0.265, 0) (0.139, 0.241, 0.03) (0.1163, 0.15, 0.046) 4.1.2. 
 3.41  Gain or Phase U nbalance  ..................................  3.41  Time Delay and Pulse Shape Unbalance  ...........  3.43  Nonlinearity in I and Q Channels  ........................ 
 Asingleradartransmitter andreceiver isswitched amongthefoursetsoffeeds onatime-shared basisevery90°rotation ofthemirror.Asintheantenna ofFig.7.13,the parabolas consistofcloselyspacedparallelwiresthatreflectthepolarization radiated bythe feed,butpasstheorthogonal polarization. Theplanarmirrorrotatestheplaneofpolarization 90°onreflection. Thebeamwillilluminate thetargettwiceforeveryrevolution oftheplanar mirror.However, thescanning isnotcontinuous inangle,andthetimebetween observations alternates between twovalues.Withasingle-sided planarmirror,thetwotimeintervals between observations correspond tothetime'ittakesfortheplanarmirrortorotate!thand ~thofarevolution. 
 M. I. Skolnik, G. 
 POLARITY 3!2 ARCHITECTURE v  )%%% 4RANSACTIONS  'EOSCIENCE AND 2EMOTE 3ENSING  VOL   PP n  .   30!#% 
 CLUTTER MODEL VERTICAL  POLARIZATION  (ORIZONTAL POLARIZATION IS VERY SIMILAR  AFTER 2 +  -OORE  + ! 3OOFI  AND 3 - 0URDUSKI Ú )%%%   4IME OF  $AY 0OLARIZATION&REQUENCY 2ANGE  '(Z#ONSTANT !  D"!NGLE 3LOPE "  D"&REQUENCY 3LOPE #  D"'(Z3LOPE #ORRECTION $  D"  r '(Z  $AY 6n 
 ERS OVERLAP  THE -4) IMPROVEMENT FACTOR FOR EACH CLUTTER SOURCE IS A FUNCTION OF THEIR SPECTRAL SEPARATION &IGURE  SHOWS THE IMPROVEMENT FACTOR FOR A DOUBLE CANCELER  WHICH CONSISTS OF  TWO SINGLE CANCELERS  EACH TRACKING ONE OF THE SPECTRA )T CAN  BE SEEN THAT AS THE SEPARA 
 17.5 (including Fig. 17.2), 1with the addition ofascale-of-three circuit toproduce the beacon switch pulse onevery third cycle. The third pulse ofthemod- ulator code iscounted down forthis purpose and passed tothe signal switching unit. 
 METRICAL RELATIONSHIP OF TRANSMITTER AND RECEIVER TO THE DUCT IN ORDER TO ASSESS THE DUCTS EFFECT AT ANY PARTICULAR FREQUENCY #ONDITION . 
 The attenuation, in decibels, through the passage depth t is approximately 27 t/s, plus  fringing losses, which are approximately 27( l /2s − 1). The power passing through the reflector, or transmission loss, can be determined  using a handy nomograph.6 One selects the grid spacing and thread radius to achieve  the transmission loss required. The resulting loss in antenna gain is termed leakage  loss, and the relationship between leakage loss and transmission loss is plotted in  Figure 12.9 for a conductive reflector (no ohmic losses). 
 no.3,pp.157-159, September, 1967.. 70.Maguire, W.W.:Application ofPulsedDoppler RadartoAirborne RadarSystems, Proc.Nurl.COllf onAeronaut. Electronics (Dayton, Ohio),pp.291-295, 1958. 
    
 Any use is subject to the Terms of Use as given at the website. Sea Clutter.  SEA CLUTTER  15.416x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 66. W. 
 1 IlF FI.1:C.I RONI(.AI.I.k' SI'I.ERE1) Pf IASED ARRAY ANTENNA IN RADAR 303  tlie tot;iI aripuliir covcr;tpc. .l'lic haridwitltli A/;, of these filters is deterrninetl by the freqirency  c1i;irige tieeded to cciiri 111c aritcr~ria bciiril orle beariiwrdtli, tI1iit is  t~ticre 0, = hcar~iwiclt ti it rid 1) = ~ipertirrc cliriiension. Substituting Eq. 
 ARRAY  THUS REDUCING THE SYSTEM COMPLEXITY 0ROVIDED THAT THE SUB 
 TAL  ATMOSPHERIC TIDES AND ASSOCIATED WINDS DRIVE THE SO 
 The periodic­ pulse waveform is a good one from the point of view of accuracy if the radar application is . EXTRACTION OF INFORMATION AND WAVEFORM DESIGN 417  ··· rd ····· __________ _j  ( 17)  (b) Figure 11.11 (a) Pulse train con­ sisting of five pulses; (b) ambi­ guity diagram for (a).  such that it is possible to ignore or eliminate any ambiguities which arise. 
 Atmos. Terr. Phys ., vol. 
 ENERGY LINEAR BEAM OF ELECTRONS THAT INTERACTS WITH THE MICROWAVE STRUCTURE TWO OR MORE MICRO 
 79. A. Farina and L. 
 (ALL    & &ABRY AND 2 * +EELER  h)NNOVATIVE SIGNAL UTILIZATION AND PROCESSING v #HAPTER  IN  2ADAR  IN !TMOSPHERIC 3CIENCE ! #OLLECTION OF %SSAYS IN (ONOR OF $AVID !TLAS  2 7AKIMOTO AND 2 3RIVASTAVA EDS   -ETEOROLOGICAL -ONOGRAPHS  6OL   "OSTON !-3    PP n  4 , 7ILFONG  $ ! -ERRITT  2 * ,ATAITIS  " , 7EBER  $ " 7UERTZ  AND 2 ' 3TRAUCH  h/PTIMAL  GENERATION OF RADAR WIND PROFILER SPECTRA v  * !TMOS /CEAN 4ECHNOL   VOL   PP n     0 ( (ILDEBRAND AND 2 ( 3EKHON  h/BJECTIVE DETERMINATION OF THE NOISE LEVEL IN DOPPLER   SPECTRA v * !PPL -ETEOROL  VOL   PP n    ( 5RKOWITZ AND * 0 .ESPOR  h/BTAINING SPECTRAL MOMENTS BY DISCRETE &OURIER TRANSFORM WITH  NOISE REMOVAL IN RADAR METEOROLOGY v  0ROC )NT 'EOSCI 2EMOTE 3ENS 3YMP ;)'!233 
 The Role ofMoving-target Indication.—The object ofmoving- target indication (MTI) istopresent the signals received byapulse radar setinsuch away that moving targets show upwhile stationary objects give noresponse. The most advanced method ofdoing this allows themoving targets tobepresented onaPPI. Figure 16.1 shows two PPI photographs, one with MT1 inoperation and one without, taken onaground radar setatBedford, Mass., using awavelength of10.7 cmand aPRF of300. 
 SCANS OF A SET OF A BURIED !4 MINE TARGETS AT DEPTH  INCREMENTS OF  MM #OURTESY )%%  .   '2/5.$ 0%.%42!4).' 2!$!2   Ó£°Îx )N THE CASE OF ANTENNAS OPERATED IN CLOSE PROXIMITY TO THE GROUND  THE ANTENNA CHARAC 
 Leibowitz, E. Willwerth, G. Meurer, C. 
 Reed: Theory of Adaptive Radar, IEEE Trans., vol. AES-9. pp. 
   PP n    3 4 7U  h0RELIMINARY  REPORT ON MEASUREMENTS OF FOREST CAN OPIES WITH # 
 748 RADAR SYSTEM ENGINEERING “1’rigatron, 379 Iligger generator forIMTI, 634 Tube (see Cathode-ray tubes; Klystrons; etc.) hve, M.A., 13 u Unloaded Q,406 U.S. TacticalAir Commands, 22%240 v Van Vleck, J.H., 59,60 Variable Elevation Beam (VEB), 189 VEB (see Variable Elevation Beam) V-beam (see Height indicator, V-beam) V-beam radar, 193–196 Veinott, C.G.,560 Vibrator power supplies (see Power supply) Video, output limiting of(8ee Limiting of video output signal level) Video amplifier (see Amplifier, video) Video mapping, 223 Video mixing, 45 Visibility, ofMTI targets, inclutter, 651-653 subclutter, 653 measurement of,679 oftarget, inclear, 64%651 inMTI, 64%653 Voltage regulation, booster armature, of dynamotors, 58o Voltage regulator, foraircraft alternators, 563-566 carbon-pile, 56G570Voltage regulator, carbon-pile, adjust- ment of,567 shock-mounting of,568 control ofmotor speed by, 574 finger-type, 570 meebanical, 56&571 VSWR (seeStanding-wave ratio, voltage) w Wrdlman, H., 448, 449 Watson-Watt, SirRobert, 14,176 Wave shape ofairborne alternators, 557 Waveform (8ee type of) Waveguide, 398-405 attenuation in,405 bends in,402 choke coupling for, 401 tocoaxial line, transition between, 403 cutoff frequency in,400 modes in,400 power-handling ability of,404 ofvariable width, 291 wavelength in,400 Waveguide rotary joint, 403 Wavelength, choice of,604 inwaveguide, 400 Waves., standing (we Standing waves) Weinstock, Robert, 64 Williams, D., 77 Wincharger Corporation, 574, 576 Window, 81 Woodcock, W., 77 Y Yagi antenna (see Antenna, Yagi) Yaw 8tabihzation, 311. 
 WAVE ABSORBERS SHOULD BE VARIED FOR OPTIMUM PERFORMANCE "Y THIS POINT  IT SHOULD BE APPARENT THAT THE APPLICATION OF RADAR ABSORBING MATERI 
 J. Bibby, C. A. 
 32. Appleton, E. V .. 
 41. pp. 549 55O. 
 Zeng, T.; Li, Y.; Ding, Z.; Long, T.; Yao, D.; Sun, Y. Subaperture Approach Based on Azimuth-DependentRange Cell Migration Correction and Azimuth Focusing Parameter Equalization for Maneuvering High-Squint-Mode SAR. IEEE T rans. 
 Fallahpour, M.; Zoughi, R. Fast 3-D qualitative method for through-wall imaging and structural health monitoring. IEEE Geosci. 
 (2.31) into (2.32) gives  The value of (SIN): is found from Fig. 2.7 as before, and nEi(n) is found from Fig. 2.Htr. 
 15.12 to15.14. Asisshown inFig. 13.48, thesynchro isdriven directly bythe amplifier without atransformer. 
 Greneker, E. F., and M. A. 
 The major differences in sea clutter for the two polarizations are seen to  lie in the range of grazing angles between about 5 ° and 60 °, where the horizontally  polarized returns are smaller. This difference is found to be emphasized at both lower  wind speeds and lower frequencies. The cross sections approach each other at high  angles ( >50°) and, for the higher microwave frequencies, at low angles ( <5°) as well. 
 12. 2.6. The Beacon Equation.-So farwehave confined ourattention to the“two-way” radar problem, inwhich the route from transmitter to receiver isacomplete round trip involving scattering ofthe energy by some remote object. 
 97. Foster, H. E., and R. 
 ]ftheseconditions aremet.thelenswillbeinsensitive to frequency.. When the particles are metallic spheres of radius u and spacing s between centers, the  dielectric constant of the artificial dielectric is approxima(e1y  assuming no interaction between the spheres.47  An artificial dielectric may also be constructed by using a solid dielectric material with a  controlled pattern of voids. This is a form of Babinet inverse of the more usual artificial  dielectric composed of particles imbedded in a low-dielectric-constant material."' The voids  may be either spheres or cylinders, but the latter are easier to machine. 
 37. H. J. 
 FORM COMPUTATION OF AIRBORNE PULSE DOPPLER CLUT 
 Spillover loss refers to feed power that misses, or spills over, the   edges of the reflector. In the radar reflector design process, one typically adjusts the  edge illumination to achieve a desired taper and sidelobe level resulting in modest  spillover loss. Spillover loss is the feed power that is lost via radiation beyond the  edges of the reflector. 
 and C.S. conceived and designed the experiments; S.W. and J.H. 
 The improvement factor shown in these figures  for rain and chaff is based on the assumption that the average velocity of the rain  and chaff has been compensated for so that the returns are centered in the canceler  rejection notch. Unless such compensation is provided, the MTI offers little or no  improvement for rain and chaff. Two further limitations on I are the effect of pulse-to-pulse repetition-period stag - gering combined with clutter spectral spread from scanning and internal-clutter motion. 
 W. Russell, “Boundary  layer clear air radar echoes: origin of echoes and accuracy of derived winds,” J. Atmos. 
 3120, 2002. 107. V . 
 SEA CLUTTER  15.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 given by r wb ∼ U 3.5.22 The average length of a breaking wavefront moving at speed c also  depends on wind speed and is given by a parameter Λ(c).23 These parameters will appear  again later when we discuss some of the more recent models for sea clutter. An additional  feature of small-scale breaking, or other strongly nonlinear events, is the appearance of  “parasitic” or “bound” capillaries attached to the event and moving with it.20,24 They tend  to be small-amplitude features, localized and narrow-band. 15.3 EMPIRICAL BEHAVIOR OF SEA CLUTTER Sea clutter is a function of many parameters, some of them showing a complicated  interdependence, so we emphasize again that it is not an easy task to establish its  detailed behavior with a great deal of confidence or precision. 
 W. Deley, “Waveform design,” in Radar Handbook , M. I. 
   LIMITED CLUTTER SEQUENCE FOR  .    HITS PER BEAMWIDTH  AFTER 4 - (ALL AND 7 7 3HRADER  Ú )%%%                 
 When a limiter is used preceding the pulse-compression filter in conventional pulse­ compression radar for suppressing impulsive and other interference, the presence of multiple  targets can cause degraded performance. If the uncompressed pulse has an amplitude less than  the rms noise level, there is little degradation. This situation will apply in many cases when the  pulse-compression ratio is large. 
 BILITY  AND LIFE OF THE ORIGINAL FORM OF THE MAGNETRON OCCURRED WITH THE INTRODUCTION OF THE COAXIAL MAGNETRON 4HE KEY DIFFERENCE IS THE INCORPORATION OF A STABILIZING CAVITY SURROUNDING THE CONVENTIONAL MAGNETRON CAVITIES  WITH THE STABILIZING CAVITY COUPLED TO THE MAGNETRON CAVITIES SO AS TO PROVIDE BETTER STABILIZATION 4HE FREQUENCY OF A COAXIAL MAGNETRON CAN BE CHANGED BY MECHANICALLY MOVING ONE OF THE END PLATES  CALLED A TUNING PISTON  OF THE STABILIZING CAVITY 4HE TUNING PISTON CAN BE POSITIONED  MECHANICALLY FROM THE OUTSIDE OF THE VACUUM BY MEANS OF A VACUUM BELLOWS )N THE COAXIAL MAGNETRON  THE OUTPUT OF EVERY OTHER RESONANT CAVITY IS COUPLED TO THE  STABILIZING CAVITY THAT SURROUNDS THE ANODE STRUCTURE 4HE OUTPUT POWER IS THEN COUPLED FROM THE STABILIZING CAVITY O -ODE OF /PERATION  ! MAGNETRON  WHETHER CONVENTIONAL OR COAXIAL  CAN OSCIL 
 TIME 
 DOPPLER COU 
 Some of the electrons emitted from the cathode  are not collected by the anode but return to the cathode by the action of the RF field and the  crossed electric and magnetic fields. When these electrons strike the cathode they produce  secondary electrons that sustain the electron emission process. Cold-cathode emission requires  the presence of both the RF drive signal applied to the tube as well as the d-c voltage between  cathode and anode. 
 In the direct method, the receiver  measures the time interval ∆Trt between reception of the transmitted signal and recep - tion of the target echo. It then calculates the range sum as ( RT + RR) = c∆Trt + L. This  method can be used with any suitable modulated transmission and any type of trans - mitter (dedicated, cooperative, or noncooperative), given an adequate LOS between  transmitter and receiver. 
 QUENCY THAT IS CONVENIENT FOR FILTERING AND PROCESSING OPERATIONS 4HE RECEIVER CAN BE TUNED BY CHANGING THE FIRST ,/ FREQUENCY WITHOUT DISTURBING THE )& SECTION OF THE RECEIVER 3UBSEQUENT SHIFTS IN INTERMEDIATE FREQUENCY ARE OFTEN ACCOMPLISHED WITHIN THE RECEIVER BY ADDITIONAL ,/S  GENERALLY OF FIXED FREQUENCY 4HESE ,/S ARE GENER 
 The HF radar wavelength is hundreds  of times greater, so the antennas are proportionately larger, as much as two or three  kilometers in length if they are to see ships, but considerably less if only aircraft are  to be detected. Transmitter average power might be on the order of several hundred  kilowatts for a skywave radar, but on the order of a few kilowatts for a microwave  ATC radar. The observation time (CIT) for skywave systems can range from one to  many tens of seconds, but is on the order of tens of milliseconds for microwave radar. 
 BASED RESEARCH RADARS CAN NOW MEASURE ATMO 
 In principle, the value of a', the sea backscatter per unit area, is  iridcpetldcnt of tl~c illutriitiatcd area. Iti practice, the area illuminated by the radar does affect  the nature of the backscatter. This is especially so with short-pulse radars. 
 Aradar employ- ingasimple scan cantelltherange ofatarget and only one ofitsangular coordinates, e.g., azimuth. Inacomplex scan the beam ranges over a certain solid angle, byvirtue ofpossessing two degrees offreedom. A radar possessing acomplex scan can tellthelocation ofatarget inspace bygiving the range and two angular coordinates, e.g., elevation and azimuth. 
 16–28, January 1955.  5. R. 
 15.18 is shown in Fig. 15.29. This graph shows the signal-to-clutter ratio improve- ment against clutter at zero doppler as a function of target doppler frequency. 
 I. Skolnik (ed.), 2nd Ed.,   New York: McGraw-Hill, 1990. 17. 
  
 The overall feed, as illustrated, is divided into small parts, and the  microwave circuitry selects the portions necessary for the sum and difference signals to  approach the ideal. One disadvantage is that this feed requires a very complex microwave  circuit. Also, the divided four-horn portions of the feed are each four element arrays that  generate large feed sidelobes in the H-plane  because of the double-peak E field. 
 The basis of this antenna is that, over small regions, a spherical surface viewed from a point halfway between the center of the circle and the surface is nearly parabolic. If the feed is moved circumferentially at constant radius R/2, where R = the radius of the circular reflector surface, the secondary beam can be steered over whatever angular extent the reflector size permits. In fact, 360° of azimuth steering may be accomplished if the feed polarization is tilted 45° and the reflector is formed of conducting strips parallel to the polarization. 
 MENTAL CHARACTERISTICS OF THE MOVING TARGET DETECTOR -OVING 
 COMPRESSION TIME SIDELOBES  ,IMITER  IS SET TO LIMIT THE SYSTEM DYNAMIC RANGE TO THE RANGE BETWEEN PEAK CLUTTER  AND CLUTTER INSTABILITY NOISE ,IMITER  IS SET SO THAT THE DYNAMIC RANGE AT ITS OUTPUT IS EQUAL TO THE EXPECTED -4) IMPROVEMENT FACTOR AS LIMITED BY CLUTTER SPECTRAL SPREAD OR LOW 
 cross-range dimension of the transmit beam R7Ab1-IS greater than that of the re- ceive beam ^AG^, so that the clutter cell is determined by the intersection of the receive beam and the range cell. For a given geometry one or the other beam will usually determine the clutter cell area. In either case the cell area increases as p increases. 
 The doppler tracking loop is closed through the microwave LO, which must, therefore, be tunable over the doppler frequency range of interest. This LO es- sentially fulfills the role of the speedgate LO in the conventional receiver of Fig. 19.5. 
 £È°xÈ  2!$!2 (!.$"//+  WHERE RA IS THE ALONG 
 Radar return is assumed to occur only for  facets oriented normal to the radar (normal orientation is required for backscatter so that  the reflected wave returns to the source). Thus, if the slope distribution of such facets is  known, the fraction normal to a given diverging beam can be established, and from this  the return can be obtained. Geometric optics assumes zero wavelength, and so the results  of such a theory are wavelength-independent, clearly not in accord with observation. 
 The sweep isusually produced by anincreasing current since, except inspecial cases, this results inthe minimum average current. Asaresult, the coil voltage drop during thesweep results inadecrease intheplate potential ofthedriver tube. The drop across thecoilreaches itsgreatest value attheend ofthefastest sweep, and thepower-supply potential must bedesigned toaccommodate this case. 
 Johnson, C. M.: Ferrite Phase Shifter for the UHF Region, IRE Trans, vol. MTT-7, pp. 
    PP n  -AY   ! &ARINA   !NTENNA 
     4HE PEAK SIGNAL 
 General Results. Being the first really comprehensive collection of clutter data over a wide range of radar frequencies, the 4FR program produced many plots showing the dependence of sea clutter on grazing angle, frequency, polar- ization, wind direction, and wind speed. However, comparison of these plots with others made both earlier and later shows the extent of the variations to be found in sea clutter measurements reported by different investigators for exactly the same set of parameters. 
 38,  pp. 771-774, July, 1950.  12. 
 This makes it,more conve-  nient to operate the radar at a remote site, and permits the outputs from many radars to be  communicated economically to a central control point.  It should be noted that the adaptive thresholding of the automatic detector can cause a  worsening of the range-resolution.-By ana10~~-to the angukr_esolu&~n possibhn the angle  coordinateE8 it wo d seem a priori that tw_otargets might be resolved in range-if their  separation is abou<.l b - f the pulse width. However, it hai been shown8' thatGith ailtomatic .- detection the probabil~ty of resmg targets in range does not rise above 0.9 until they are  separated by 2.5 pulse widths. 
 TED AND RECEIVED PULSES !LL THE LOCAL OSCILLATORS ARE PHASE REFERENCED TO THE SAME  MASTER  OSCILLATOR  WHICH IS ALSO USED TO PRODUCE THE TRANSMITTED WAVEFORM 4HE  IN 
 Total Radar Instability.  The primary sources of radar instability are usually the  receiver-exciter common phase noise, receiver and exciter uncommon phase noise,  and the transmitter phase noise. If the spectra of these components are available, either  through measurements or through predictions based on similar devices, the convolu - tion of receiver-exciter common phase noise, modified by the range-dependent effect  with the other components, provides an estimate of the spectrum of returns from stable  clutter, which is then modified by the receiver filters and integrated to obtain the resi - due power caused by these contributors. 
 D. Rosenberg, “Very high  frequency radio wave scattering by a disturbed sea surface,” IEEE Trans ., vol. AP-16,   pp. 
 Raindrops are spherical, or nearly so, but aircraft are complex targets. Thus the  backscattered energy from rain and aircraft will be affected differently by the polarization of  the incident radar energy. Advantage can be taken of this difference to enhance the target-to­ clutter ratio when the clutter background is precipitation. 
 CPI = nine pulses. Chebyshev filter design performs against a given clutter model. Also shown is the average SCR improvement for both the optimum and the Chebyshev filter bank. 
 KT WINDS WITH  
 The right multiplication of the matrix Uwith Sonly scales the vector columns in Unot affecting the orthogonality property. As a simple example, the SVD decomposition of the matrix Xmade of only two columns requires the right singular vector matrix Van orthonormal matrix of size 2. The Vmatrix in this simple case represents a complex Gibbs rotation matrix. 
 ÓÈ°Óä  2!$!2 (!.$"//+  PLAYED IN THE 5NITED 3TATES )T WAS ATTENDED BY OVER   PEOPLE  ALL CONFINED IN  ONE SPORTING EVENT STADIUM  WHICH PRESENTED A SIGNIFICANT TARGET FOR A TERRORISM ATTACK 4HE DISPLAY SHOWS A RADAR PROBABILITY OF DETECTION IN A RANGE VERSUS HEIGHT DEPICTION  RADAR PROBABILITY OF DETECTION VERSUS RANGE AT A CONSTANT ALTITUDE DEPICTION  AND RADAR PROBABILITY OF DETECTION VERSUS HEIGHT AT A CONSTANT RANGE DEPICTION 4HIS DISPLAY IS COURTESY OF THE TH 2ADAR %VALUATION 3QUADRON  (ILL !IR &ORCE "ASE  5TAH 4HE RADAR DEPICTED IS THE !232 
 FIELD REQUIREMENT IS GENERALLY FELT TO YIELD DATA WITH AN ACCURACY OF   D" OR BETTER  &IGURE  ILLUSTRATES  THE FAR 
 AES–38, no. 3, pp. 1023–1037, July 2002. 
 PASS CHARACTERISTIC RESULTS IN AN OVERSHOOT WHEN THE ANTENNA AXIS MOVES TO ALIGN WITH THE TARGET (IGH PEAKING CAUSES A LARGE OVERSHOOT AND A RETURN TO THE TARGET WITH ADDITIONAL OVERSHOOT )N THE EXTREME AS IN SYSTEM ! SHOWN IN &IGURE  B    THE ANTENNA ZEROS IN ON THE TARGET WITH A DAMPED OSCILLATION !N OPTIMUM SYSTEM COMPROMISE BETWEEN SPEED OF RESPONSE AND OVERSHOOT  AS IN SYSTEM "  ALLOWS THE ANTENNA TO MAKE A SMALL OVERSHOOT WITH REASONABLY RAPID EXPONENTIAL MOVEMENT BACK TO THE TARGET 4HIS CORRESPONDS TO ABOUT  D" PEAKING OF THE CLOSED 
 The double-bounce signal.  Reflections from the landing gear can also cause errors. 88 INTRODUCTION TO RADAR SYSTEMS  Receiver  Figure 3.14 Unwanted signals in FM altimeter. 
 26, pp. 774–789, 1988. 33. 
 EST USING THE *%23 
 0.  E  <( I  I  I  I  I  I I ... ·.;:::  I ·;:;; 1·;:;;  0 1£ I Cl. 
 Any use is subject to the Terms of Use as given at the website. Airborne MTI. 3.26  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 T2Transmit Module (1) Transmit Module (m) D1… DmDigital Receiv er (1) Digital Receiv er (m)… T1 TN−1 Digital Beamformer …T2T1 TN−1… Adaptiv e Weight Generator …Waveform Generator Automatic Detector Ti; i = 1 − N − 1; PRI delays FIGURE 3. 23 STAP radar block diagram PRIElementDoppler ElementTemporal Filtering (DFT) PRIBeam (or Subarray) Doppler Beam (or Subarray)Temporal Filtering (DFT)Spatial FilteringSpatial FilteringSpace/Time FilteringElement Space Pre-DopplerElement Space Post-Doppler Beam Space Post-DopplerBeam Space Pre-Doppler FIGURE 3. 
 SENTED AS SINGLE 
 98. Kossiakolf. A .. 
 In some instances, propeller modulation can be  of advantage. It might permit the detection of propeller-driven aircraft passing on a tangential  trajectory, even though the doppler frequency shift is zero. The rotating blades of a helicopter  and the compressor stages of a jet engine can also result in a modulation of the echo and a  widening of the spectrum that can degrade the performance of CW doppler radar. 
 Waves have their origin ultimately in the wind, but this does not mean that the "local" wind is a particularly good indicator of what the wave structure beneath it will be. In order to arouse the surface to its fully developed or equilibrium state, the wind must blow for a sufficient time (duration) over a sufficient distance (fetch). That part of the wave structure directly produced by these winds is called sea. 
 Furthermore, if compact and  high-speed processing are requested, spatial and frequency diversity techniques can  be fruitfully implemented resorting to systolic schemes. FIGURE 24.5  Blanking probability ( PB) and target blanking probability ( PTB)  versus the blanking threshold F (in dB) for the frequency diversity schemeF (dB) d/λ = 0.5−10 −5 0 5 1 00.10.20.30.40.50.60.70.80.91 d/λ = 0.55OR PTBPBPB, PTBOR d/λ = 0.55d/λ = 0.5 ch24.indd   19 12/19/07   6:00:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
  
 The difference pattern A is used to generate an in-phase correction for scanning motion and a quadrature correction for platform motion. This pro- cess yields the set of resultant signals Rip where the subscript / denotes the pulse pair The compensation required by AG2(0)/2 can be determined from a Taylor's series expansion of G2(8). In the preceding discussion we used the first derivative. 
 Acomplete three-dimensional plotoftheradiation patternisnotalwaysnecessary. For example, anantenna withasymmetrical pencil-beam patterncanberepresented byaplotin oneangularcoordinate. Theradiation-intensity patternforrectangular apertures canoftenbe writtenastheproductoftheradiation-intensity patterns inthetwocoordinate planes;for instance, P(U,4»=P(O,O)P(O,4» Thecomplete radiation patterncanbespecified fromthetwosingle-coordinate radiation patterns inthe(}planeandthel'plane. 
 This also improves  the reliability. The tritium-activated TR is usually followed by a diode limiter. The combina-  tion of the two is called a passive TR-lirniter and is widely used as a receiver protector. 
 PERFORMANCE  INEXPENSIVE POLARIMETRIC  RADAR FOR IN SITU MEASUREMENTS v 0ROC )'!233  VOL   PP n     2 + -OORE  h%FFECT OF POINTING ERRORS AND RANGE ON PERFORMANCE OF DUAL 
 919 may not beline-of-sight stabilized. Ifthis airplane banks, the relative bearing ofground targets will be,asweshall see, falsely indicated. For example, letusconsider thecase ofanairplane banking foraright turn, the relative bearing ofthebeam being straight ahead. 
 Shannon, C.E. A mathematical theory of communication. Bell Syst. 
 (b) SSN = 100.Ground Range (nmi) (a) . Loss (dB) Frequency (MHz) or El. Angle (deg) Noise (dBW) Loss (dB) Frequency (MHz) or El. 
 TARGET  "ECAUSE THE FILTER WILL USE SIX PULSES  ONLY FIVE ZEROS ARE AVAILABLE FOR THE FILTER DESIGN THE NUMBER OF ZEROS AVAILABLE IS THE NUMBER OF PULSES MINUS ONE 4HE FILTER DESIGN PROCESS CONSISTS OF PLACING THE ZEROS TO OBTAIN A FILTER BANK RESPONSE THAT CONFORMS TO THE SPECIFIED CONSTRAINTS 4HE EXAMPLE THAT FOLLOWS WAS PRODUCED WITH AN INTERACTIVE COMPUTER PROGRAM WITH WHICH THE ZEROS COULD BE MOVED UNTIL THE DESIRED RESPONSE WAS OBTAINED 4HE ASSUMED FILTER REQUIREMENTS ARE AS FOLLOWS L 0ROVIDE A RESPONSE OF  
 Brunkow, V. N. Bringi, P. 
 1 The delayed pulse reaches thefarend ofthedelay line exactly atthe middle ofthe switching wave. The remainder ofthe circuit isdesigned toforce thk “comparison” pulse into time coincidence with the sine pulse byproperly controlling the delay through adjustment ofthe out- put voltage. Various methods can beused toaccomplish this adjust- ment. 
 “Peak” noise is then about $oflimit level. This adjustment ofnoise relative tolimit level ismade while viewing the output ofthe limiting receiver onan A-scope. JVhen this has been done, the video gain control isadjusted sothat thenoise and canceled residue just show onthePPI. 
 SITE REGION JUST AS IT WOULD FOR A COOPERATIVE TRANSMITTER 4HE 'ERMAN  +LEIN  (EIDELBERG HITCHHIKING OFF THE "RITISH  #HAIN (OME RADARS TO CONDUCT AIR SURVEILLANCE  DURING 77)) IS AN EXAMPLE   ! HITCHHIKER IMPLANTED IN OR FLYING OVER HOSTILE AREAS  COULD USE ANY HIGH 
 OF 
 THE 
 £ £ COS   P+N M . M. 
 CM WAVELENGTHS  AS NOTED BY (ILDEBRAND  AND !LLEN ET AL )N SOME METEOROLOGICAL RADAR APPLICATIONS  IT IS DESIRABLE TO ATTEMPT TO MEASURE  ATTENUATION ALONG SELECTED PROPAGATION PATHS 4HIS IS DONE BECAUSE ABSORPTION IS RELATED TO LIQUID 
 Antennas  Propag ., vol. 7, pp. 223–226, July 1959. 
 In general, periodic waveforms may be designed to satisfy the require­ ments of accuracy and resolution provided the resulting ambiguities can be tolerated. A  waveform consisting of a single pulse of sinusoid avoids the ambiguity problem, but the time  delay and frequency cannot simultaneously be measured to as great an accuracy as might ~e  desired. However, it is possible to determine simultaneously both the frequency and the time  delay to any degree of accuracy with a transmitted waveform containing a large bandwidth  pulse-width product (large pcx. 
 It  is important if the electromagnetic spectrum, considered as a natural resource, is to be effec-  tively and efficiently utilized for the benefit of all. Military radars, however. must also operate  in a hostile environment where they may be subjected to deliberate interference designed to  degrade their performance. 
 71. Hsiao, J. K.: MTI Optimization in a Multiple-Clutter Environment, NRL Report 7860, Narnl  Research Laboratory, Washington, D.C., Mar. 
 ,,",-Ê­/, 
 MATED ANGULAR POSITIONS OF RADAR TRACK  J WITH RESPECT TO SITES  AND   THEN THE MULTISITE  SQUARED ERROR IS SIMPLY  DT TJ IN EI JI KJ 
  0ART )  0ART ))  3UPPLEMENT )  &EBRUARY      % * "ARLOW  h$OPPLER RADAR v  0ROC )2%  VOL   PP n  !PRIL    7 , 3IMKINS  6 # 6ANNICOLA  AND * 0 2OYAN  h3EEK )GLOO RADAR CLUTTER STUDY v 2OME !IR  $EVELOPMENT #ENTER  2EPORT .O 2EPT 42 
 Moore, J. M. Headrick, and R. 
  
 Ó°ÈÈ  2!$!2 (!.$"//+  PHASE CHANGE IF A POWER AMPLIFIER  FROM THE INABILITY TO LOCK THE COHO PERFECTLY TO THE  PHASE OF THE REFERENCE PULSE  FROM TIME JITTER AND AMPLITUDE JITTER ON THE PULSES  AND FROM QUANTIZATION NOISE OF THE !$ CONVERTER   0HASE INSTABILITIES WILL BE CONSIDERED FIRST )F THE PHASES OF CONSECUTIVE RECEIVED  PULSES RELATIVE TO THE PHASE OF THE COHO DIFFER BY  SAY   RAD  A LIMITATION OF  D" IS IMPOSED ON  ) 4HE  
 1H,Nyquist, Phys.Rev.34,110(1928), SeealsoVol.24ofthisseries, Chap. 4. SEC. 
 C'asr) 2. The probnhility-derlsity function for the target cross section is also given by Eq. (2.39a). 
 zMore detailed discussions willbefound inPulse Generators, Vol. 5ofthisseries, andinMicrowave Magnetrons, Vol. 6. 
 1, pp. 242-247, 1956.  39. 
 The large advantage is the extremely high sensitivity due to the narrow  bandwidth.  The analysis is almost exclusively based on phase and phase difference measur e- ments.  Problems can arise with targets having a velocity difference of  zero. 
 However, as radar powers increase, the likelihood of biological  damage becomes greater, and if serious harm is to be avoided, proper safety precautions must  be observed. The United States armed services have established63·67 the maximum safe con­ tinuous exposure level to be an average power density or JO mW/cm2• There has been sub­ stantial basis for setting this limit. However, when working under conditions of moderate to  severe heat stress the maximum exposure level should be reduced appropriately. 
 ( c) Oil Tanker image with random crop. The D3 classiﬁcation data set is processed with proposed method, divided into two sets: the training data set Dtrain3 (with 13,823 samples) and the validation data set Dval3 (with 8127 samples), as shown in Figure 13.     (a) (b) (c)  Figure 13. 
 METEOROLOGICAL RADAR  19.396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 19 to offer the only practical mechanism for obtaining these measurements. The TRMM  satellite was launched in 1997 carrying the Ku-band single frequency Precipitation  Radar (PR)179 and a 2.4 m single beam array antenna that is steered 17 ° on either side  of the spacecraft track. Its relatively low inclination orbit at 350 km altitude provides  tropical precipitation measurements with 250 m range resolution and a 4.5 km foot - print over a 250 km swath. 
 M RANGE RESOLUTION IS SET BY THE UNITY TIME 
 Figure 20.8 gives the vertical-polarization RCS of a rod and a hemisphere mounted  on a perfectly conducting surface. With these canonical shapes, an estimate of RCS  can be made for surface craft by matching L and R to the principle dimensions to the  target. For small vessels, the mast height will be of most importance.74 For surface  targets, where the maximum RCS occurs with vertical polarization, a 12 dB skywave  RCS enhancement results from the image field. 
 64D, pp. 483-486, September/October, 1960.  39. 
 More precisely, -T 12 Pt = \fw(t)dt (2.12) where W(t) is the instantaneous power (a function of time, t). The definition of W(O, however, excludes "spikes," "tails," and any other transients that are not useful for radar detection. The time interval T is the pulse period (= 1/PRF, where PRF is the pulse repetition frequency in pulses per second). 
 The ratio of the peak to therms error is found experimentally  to be about 3: 1. This truncation or errors occurs since large errors usually are corrected in  manufacture.  The effect of errors in array antennas and further discussion of errors in continuous  apertures is given in Sec. 
 Separate antennas are'·shown.f9r,transm"ission andreception. Insteadoftheusuallocaloscilla­ torfou~din.the.con~entjo?~~\~~~~~et~"'O?Yn.e ,receiver, th.eloc~loscill~tor (~rreference signal) ISdenvedmthiSreceiverfromaportionofthetransmitted SignalmixedWithalocally generated signaloffrequency equaltothatofthereceiverIF.Sincetheoutputofthemixer. CW AND FREQUENCY-MODUL,ATED RADAR 75  filler  Rece~vlnq  antenna  2 d Doppler  mixer ornplif~er detector amplrfier - Indicator  fo ? (j fd  Figure 3.4 Block diagram of CW doppler radar with nonzero IF receiver, sometimes called sideband  srrperheterodyne. 
 Broken-line curves are lower bounds derived by Swerling,6 and points shown are simulation results. (Copyright 1970, IEEE; af- ter Ref. 9.) spacing10 and will approach o-(0A) = A0/Vl2 (8.6) where A0 is the angular rotation between transmitted pulses. 
 DESIGN REQUIREMENTS FOR REDUCED RADAR CROSS SECTION AND SIG 
 The raster, or TV, scan, unlike the Palmer or the spiral scan, paints the search area in a  uniform manner. The raster scan is a simple and convenient means for searching a limited  sector, rectangular in shape. Similar to the raster scan is the nodding scan produced by oscillat­ ing the antenna beam rapidly in elevation and slowly in azimuth. 
 4.2b. The doppler signal may be readily  discerned from the information contained in a single pulse. If, on the other hand, fd is small  compared with the reciprocal of the pulse duration, the pulses will be modulated with an  amplitude given by Eq. 
 Woodward5 coined the  name to demonstrate that the total volume under this function is a constant equal to (2E)2,  independent of the shape of the transmitted waveform, [Eq. ( 11.54 )]. Thus the total area of  ambiguity, or uncertainty, is the same no matter how ·I x(TR, fJ) 12 is distributed over the TR, fd  plane, as illustrated by the sandbox analogy mentioned earlier in this section. 
 .., etc., or when  where rl = 0, 1, 2, . , and j, = pulse repetition frequency. The delay-line canceler not orlly  eliminates the d-c component caused by clutter (n = O), but unfortunately it also rejects any  moving target whose doppler frequency happens to be the same as the prf or a mt~ltiple  thereof. 
 LOOK PROCESSING MEANS A FULLY COHERENT USE OF THE BANDWIDTH BEST GEOMETRIC RESOLUTION   AND IN THIS CASE  THE SPECKLE NOISE WILL OBEY AN EXPONENTIAL DIS 
 Also at short ranges, because there is  no sidelobe suppression circuitry, SARTs can be triggered by radar sidelobes. To  prevent adjacent SARTs from continuously triggering each other, there is a short  delay after a SART transmission before it may be triggered again. To detect SARTs  in heavy sea clutter, it is often best to detune the radar receiver, eliminating all  other returns. 
 A. Ruetz: High-Power Linear-Beam Tubes, Proc. IEEE, vol. 
 WALL  CROSS  SECTIONS A  SINGLE LAYER   B  ! 
 .....665 16.18 The Supersonic Delay Line. 667 16.19 Delay-line Signal Circuits : .. 672 16.20 Delay-line Trigger Circuits 675 16.21 Special Test Equipment 677 CHAP. 
 563–580, May-June 1995. 77. J. 
 (In the math- ematical theory of thermal noise, there is a nonzero probability that it can attain any finite value, however large.) The probability that Vt is exceeded when no sig- nal is present is the false-alarm probability. It is calculated from the equation . Pfa = fPnMdV (2.18) Vt where pn(v) is the probability density function of the noise. 
 UPv TARGETS  WEAPON CONTROL  MISSILE GUIDANCE  NONCOOPERATIVE TARGET RECOGNITION  AND BATTLE DAMAGE ASSESSMENT 4HE PROXIMITY FUZE IN MANY WEAPONS IS . 
 272-273, February, 1970.  43. Skolnik, M. 
 (AfterDaley,etal.J). which such measuretnetlts cat1 be made. I'tie solid curves of Fig. 
 range instrumentation. In both applications a high degree of precision and an ac- curate prediction of the future position of the target are generally required. The earliest use of tracking radar was in gunfire control. 
 C. Kopp; “The properties of high capacity microwave airborne ad hoc networks,” Ph.D.   dissertation, Monash University, Melbourne, Australia, October 2000. 
 RESPONSE &)2  FILTER DESIGNS ARE REALISTIC CANDIDATES FOR THE FILTER BANK  DESIGN &EEDBACK FILTERS REQUIRE A NUMBER OF PULSES TO SETTLE AFTER EITHER THE 02& OR  THE 2& IS CHANGED AND THUS WOULD NOT BE PRACTICAL  4HE NUMBER OF PULSES AVAILABLE DURING THE TIME WHEN A SURVEILLANCE RADAR BEAM  ILLUMINATES A POTENTIAL TARGET POSITION IS DETERMINED BY SYSTEM PARAMETERS AND REQUIRE 
 The cross section of any nonspherical target is a function of the aspect angle from which it is viewed by the radar. It may also be a function of the polarization of the radar electromagnetic field. Therefore, in order to be wholly meaningful, a radar range prediction for a specific target, such as an aircraft, must stipulate the target aspect angle assumed and the polarization employed. 
 A third system may be  needed to give very precise marking of small targets, or  so that a number of tactical targets can be covered  simultaneously by a considerable number of aircraft.  The G-H system offers possibilities, and it is derived  from the Gee system. The ‘H’ principle consists of  measuring with great precision the range of an aircraft  or ship from two fixed beacons. 
 TERM BASIS S OF MS v )T IS ALSO SAID THAT hBANDWIDTH OF SEVERAL '(Z ON TRANSMITv IS REQUIRED  AND THIS IS WITHIN THE CAPABILITY OF SOLID 
 Thusthecorrect valueisuncertain. The ambiguity diagram permits avisualindication oftheambiguities possible withaparticular waveform. Theambiguity problem ischaracteristic ofasingletarget,asisthedetection and accuracy requirements ofawaverorm, whereas resolution isconcerned withmultiple targets. 
 Figure 7.30 E-2C AEW aircraft with rotodorne antenna.  268INTRODUCTION TORADAR SYSTEMS wallcontlgurations d-:scrib-:d ahov-:arcapplicable toairborn-: radars,bUIanotlJ-:f approach is basedonthefactthatametalsheetwithperiodically spacedslotsexhibits abandpass charac­ teristic.Thusthinmetallic radomes, piercedwithmanyopenings (slots)tomakeittranspar-:nt tomicrowaves, offerthepossibility ofovercoming themechanical limitations ofdielectric radomes, yetresultingoodelectrical properties.106lOllAmetallic structure notonlyhasth~ potential forgreater mechanical strength thandielectric radomes andtobettcrdistribute frictionally-induced heating, butitshouldbeabletobetlerwithstand thestresses causedby rain,hail,dust,andlightning. Staticbuildup ofchargeandsubsequent discharg-: toth~ airframe, encountered withdielectric radomes, canbeeliminated withmetallic radomes. 
 517-527, July. 1972.  19. 
 SAR imaging: An autofocusing method for improving image quality and MFS image classiﬁcation technique. In Applications of Mathematics and Informatics in Science and Engineering ; Daras, N., Ed.; Hellenic Military Academy: Vari Attikis, Greece, 2014; pp. 199–215. 
 As an example, the response of the optimum filter designed for one particular target doppler frequency labeled as point A in Fig. 15.18 is shown in a broken line. At approximately ±5 percent from the design doppler the performance starts to fall significantly below the op- timum. 
 If the main beam is pointed below the horizon, the main-beam clutter spectral width  ∆f due to platform motion measured 6 dB down from the peak is approximately34   ∆fVR BB= + +2 80 02 0 0 λθ φ θθ φ θcos( )sin( )cos( )cos( ) c c hτ φ θ φsin ( )cos( ) cos( )3 0 0 0 2     (4.4) ch04.indd   16 12/20/07   4:52:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar. 
 LARLY WHEN THE ANTENNA IS MOUNTED ON AN AIRCRAFT OR OTHER METALLIC OBJECT .EVERTHELESS   COMPLETE PATTERNS ARE A MUST FOR GOOD SCATTER MEASUREMENTS 2ANGE 
 The  amplitude of the clutter returns depends on the size of the resolution cell of the radar,  the frequency of the radar, and the reflectivity of the clutter. The expected radar cross  section of clutter can be expressed as the product of a reflectivity factor and the volume  or area of the resolution cell. For surface clutter, as viewed by a surface-based radar,  σ στσ = ⋅ = ⋅ ⋅⋅⋅ A Rc c0 0 2qaz  (2.17) where σ is the average radar cross section, in square meters; Ac is the area of clutter  illuminated, in square meters; R is the range to clutter, in meters; qaz is the one-way  half-power azimuthal beamwidth, in radians; c is the speed of propagation, 300 million  m/s; t  is the half-power radar pulse length (after the matched filter), in seconds; and s 0  is the average clutter reflectivity factor, in square meters per square meter. 
 Arid Land 2017 ,9, 778–789. [ CrossRef ] 11. Pratesi, F.; Tapete, D.; Del Ventisette, C.; Moretti, S. 
 W. Finney, L. L. 
 302 ANTENNAS, SCANNERS, ANDSTABILIZATION [SEC.9i6 theimpedance match inthis angular region byabsorbing such radiation asmay trytoleak across that region asthehorn approaches. 9.16. Other Types ofElectrical Scanners.—Probably thefirst electri- calscanner tobeused, developed byBell Telephone Laboratories, operates Thistriangular arearemainsflat D IFoldline Cylinde; elements Y.’_z: E locus IFeedposition, O, forbeamonaxis FIG.9.30.— Illustration oftrapezoid before, during, andafter rolling. 
 UNIT DECREASE  WITH HEIGHT  4HE FIRST TYPE OF DUCT IS A SURFACE DUCT CREATED FROM A SURFACE 
 A very readable  description of the history of radar development at TRE (Telecommunications Research Establish­ ment, England) and how TRE went about its business from 1935 to the end of World War II.  11. Watson-Watt, Sir Robert: "Three Steps to Victory," Odhams Press, Ltd., London, 1957; "The Pulse of  Radar," The Dial Press, Inc., New York, 1959. 
  *K (TK  =0K    \  K    . Ç°Îä  2!$!2 (!.$"//+  USING THE +ALMAN GAINS   *K    0K    \ K (4TK  ;(TK  0K    \ K (4TK     K= 
 HORN FEED GIVES A LOWER ANTENNA EFFICIENCY   THAN AN OPTIMUM MULTIMODE MONOPULSE FEED  WHICH CAN APPROACH AN EFFICIENCY OF   ALTHOUGH ITS ANGLE SENSITIVITY IS LESS  TYPICALLY HAVING A VALUE  OF  4HEREFORE  THERE IS A TRADEOFF BETWEEN SLOPE AND EFFICIENCY ! SLOPE FOR MONO 
 TIVE PROCESSING 34!0  n 34!0 MAY BE THOUGHT OF AS A TWO 
 Because the range resolution is pro - portional to the reciprocal of the bandwidth, wider-bandwidth pulse compression  waveforms can offer greater clutter rejection.Factor Linear FM Nonlinear FM Binary Phase Coded Polyphase Coded Doppler  toleranceSupports doppler  shifts up to ± B/10.  Time shift of fdT/B  is introduced by  range-doppler  coupling.  Time sidelobe  performance  remains excellent  for large doppler  shifts.Adequate insensitivity  to doppler to allow use  generally up to Mach 1. 
 58.Poling,A.c.:Tellurometer Manual, U.S.Dept.Commerce PI/bl.62-1,1959. 59.Robinson, T.A.:Application ofElectronic Distance Measuring Equipment inSurveying, IRETrans., vol.MIL-4,pp.263-267, April-July, 1960. 60.Varian, R.H.,W.W.Hansen, andJ.R.Woodyard: ObjectDetecting andLocating System, LJ.S. 
 7 .44  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 where lF is the ratio of the size of the possible space a target can travel in one detection  interval to the size of entire clutter region G,  λFDV G=( )MAX  (7.41) and lP is the ratio of the size of a radar resolution cell to the size of the entire clutter  region G  λτ τ PD G=⋅ ⋅ ⋅1  (7.42) ti being the resolution “distance” in the ith dimension, and g�(D, N, M) being the com - binatorial term:  γ( , , ) ( )( )D N M NN MD DM= −− −  −11 121  (7.43) Figure 7.37 gives an example of the application of Eqs. 7.40 to 7.43 to a radar  with lP = 2.10−3 and lP = 10−5. Increasing the number of detections required to form  FIGURE 7.37  Variation of the expected number of false tracks with the track formation M-out-of- N crite - rion ( after W. 
 The angular position of the dipole elements is relatively unimportant. 113  The following conclusions apply to the continuous antenna:  L According to Ruze, 112 the spurious sidelobe radiation is proportional to the mean square  error, just as in the discrete array, and in addition is proportional to the square of the  correlation interval measured in wavelengths. Bates 114 defines his correlation interval dif­ ferently from Ruze and obtains a first-power dependence for this reason. 
 Johnson. R. C.: The Geodesic Luneburg Lens. 
 Allen, “On array element impedance variation with spacing,” IEEE Trans ., vol. AP-12,   p. 371, May 1964. 
 527. 532. IEEE Puhlication 75 CHO 938-1 AES. 
 BASED 3!2 )T WAS THE FIRST SYSTEM TO OFFER THE USER A CHOICE OF RESOLUTIONS  INCIDENT ANGLES  AND SWATH WIDTHS  4HE EVOLUTION OF THESE CHARACTERISTICS MERITS A  BRIEF REVIEW 4HE #ANADIAN REQUIREMENTS  SPANNED A VARIETY OF AP PLICATIONS  FROM OCE 
 1.16x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 An Introduction and  Overview of Radar* Merrill Skolnik 1.1 RADAR IN BRIEF Radar is an electromagnetic sensor for the detection and location of reflecting  objects. Its operation can be summarized as follows: ● The radar radiates electromagnetic energy from an antenna to propagate in space. 
  SHOWN IN &IGURE  !S SUCH  THE INTAKES ARE SHIELDED FROM GROUND 
 P. Kapteijin, E. Deprettere, L. 
 Furthermore, the mechanisms for feeding the elements and steering the beam of a conformal  array, as well as the generation of the phase-shifter commands, are generally more complicated  than those of a planar array. Although it is desired that conformal arrays be applicable to any  surface, the complications that arise when dealing with a general nonplanar surface have  restricted its consideration to relatively simple shapes, such as the cylinder, cone, ogive, and  sphere. Even these shapes present difficulties in analysis and equipment implen~entation, and  in realizing antennas competitive with the planar array. 
 The maximum cumulative subsidence has reached up to −126.43 mm, is located in Xinrong of HK, see Figure 4. The time series of subsidence at ﬁve typical PS points marked as A–E in Figure.4, is shown in Figure 6. Points A, B, C, and D are located in HK, BSZ, NSL, and QSIZ, respectively, which are the four major areas of subsidence. 
 The blocking capacitors are used because of the dc offset voltage that is characteristic of this form of limiter. Digital Logarithm. The trend toward digital processing requires mention of a piecewise linear digital approximation which may be accomplished after analog-to-digital conversion and digital doppler filtering to suppress clutter . 
 April. 1959; also IRE Trans., vol. AP-8, pp. 
  
 99. C'asner. P. 
 Information about the radar backscatter from land is required for several different appli­ cations, each of which has its own special needs. These applications include:  ' The detection of' aircraft 01•er land, where the clutter echoes might be as much as 50 to 60 dB  greater than aircraft echoes. MTI or pulse-doppler radar is commonly used for this  application to remove the background clutter. 
 171. Sensors 2018 ,18, 3750 4.3. Actual Measurement Experiment in Anechoic Chamber In order to further verify the effectiveness of the proposed approach in terms of practical applications perspective, a near-ﬁeld InISAR test platform in an anechoic chamber is established, and the test system is shown as Figure 13. 
 The response g(t) of the  entire input function x(t) results from the summation of all impulse functions.  . Radar System Engineeri ng Chapter 8 – Pulse Radar  66     € g(t)= x(τ) τ=t1t2 ∑ ⋅h(t−τ)⋅Δτ (8.18)   In the limit the following is obtained:   € g(t)= x(τ)⋅h(t−τ)dτ t1t2 ∫  (8.19)   As shown by Figure 8.19, the chosen example of linear FM is the normalized time function of  the pulse. 
 Theorderinwhichthediscretefrequencies aretransmitted canbevariedsothateachradarcanhaveitsowncode,andinterference between radarswillbe reduced. Thecomponents ineachchannel needonlyhaveabandwidth liNtimesthetotal processing bandwidth. Stillanotheradvantage ofsuchsystems isthatastrongCWinterfer-. 
 The demodulator, using  a reference from the drive on the rotating coupler, extracts the sine and cosine  components from ∆ to give the azimuth- and elevation-error signals. The modulation  caused by the microwave resolver is of concern in instrumentation radar applications  because it adds spectral components in the signal, complicating the possible addition  of pulse doppler tracking capability to the radar. This system provides instantaneous AGC operation with only two IF channels and  operation with reduced performance in case of failure of either channel. 
 It is  iisually not practical to obtain the experimental data necessary to compute the probabiiity-  density function and the autocorrelation function from which the overall radar performance is  determined. Most radar situations are of too complex a nature to warrant obtaining complete  data. A more economical method to assess the effects of a fluctuating cross section is to  postulate a reasonable model for the fluctuations and to analyze it mathematically. 
 CODED  WAVEFORMS 4HE SYSTEMS ARE COMPARED ON THE ASSUMPTION THAT INFORMATION IS EXTRACTED BY PROCESSING A SINGLE WAVEFORM AS OPPOSED TO MULTIPLE 
 Another type of absorber is one which internally dissipates the energy incident upon it. It  is usually much thicker than the destructive interference absorber but has the advantage of  being broadband. Relatively thin absorbers, however, can be obtained with magnetic materials  having appropriate dielectric properties.99·100-104  14.6 BISTATIC RAOAR57·58  Throughout this book, it has been assumed that a common antenna is used for both transmit­ ting and receiving. 
 To further analyze the inﬂuence of 322. Sensors 2019 ,19, 1529 the radar look direction on SAR eddy imaging, ΔσandΔσrof Figure 12a–d were calculated. The results are shown in Figure 13. 
 2.11 occurs atanelevation angle ofA/4hl radians. Below this angle the field strength diminishes until, atthereflecting surface itself, itvanishes. X’o modification ofthe above argument isrequired fora diwcti~e antenna atA,unless thedirectivity ishigh enough toaffect the relative intensity ofthe waves traveling along All and AM (Fig. 
 Once Wi1, m2, and W3 have been chosen, the range can be computed from Eq.(17.6) by using the C values and the ambiguous-range cell numbers (A19A29A3) in which the target is detected. For example, if W1 = I9 W2 = S9 w3 = 99 then 6X = 4, 62 = 7,63 = 5, and the range is/?c = (288^1 + 44IA2 + 28(M3) (modulo 504). If the target is in the first gate after the transmit pulse, ^1 = A2 = A3 = 1 and Rc= (288 + 441 + 280) (modulo 504) = 1. 
            . Ó°{  2!$!2 (!.$"//+  IS ALSO USED AS A PHASE REFERENCE FOR DETERMINING THE PHASE OF REFLECTED SIGNALS 4HE  PHASE INFORMATION IS STORED IN A PULSE REPETITION INTERVAL 02)   MEMORY FOR THE PERIOD  4  BETWEEN TRANSMITTED PULSES  AND IS SUBTRACTED FROM THE PHASE INFORMATION FROM THE  CURRENT RECEIVED PULSE 4HERE IS AN OUTPUT FROM THE SUBTRACTOR ONLY WHEN A REFLECTION HAS OCCURRED FROM A MOVING TARGET -OVING 
 $OPPLER  %LEMENT !NTENNA 34!0  4HE SECOND TYPE OF TRANSFORMATION  LEADS TO WHAT ARE CALLED POST 
 P. de Loor and P. Hoogeboom, “Radar backscatter measurements from Platform Noordwijk  in the North Sea,” IEEE J. 
 18. E. P. 
 Dotted line: pattern of array of elements and  of array of sub-arrays after noise normalization and weight rescaling. The numerical example follows with Figure 24.10, which portrays the cancellation  of a jammer with the DoA = –50° and a JNR of 30 dB. The continuous line refers to  an unadapted pattern, tapered at the element level, whereas the dotted line pertains to  the adapted pattern at the sub-array level. 
 MIL-6, pp. 153-161, April, 1962.  41. 
 In general terms, fluorescence may be thought of as  luminescence which ceases almost immediately upon removal of the excitation, whereas in  phosphorescence the luminescence persists. Cascaded screens produce different colors under  fluorescence or phosphorescence.  Not all long-duration screens need be cascade. 
 By letting 7 become very large (essentially infinite), Fig. 11.10 may also be used to repre-  sent a CW radar. Similarly, by letting r be very small (infinitesimal), the diagram applies to an  impulse radar. 
 The residue from clutter in the left photo - graph is solid out to 3 nmi and then decreases until it is almost entirely gone at 10 nmi.  The MTI improvement factor in both pictures is 18 dB, but the input dynamic range  (peak signal-to-rms noise) to the canceler was changed from 20 to 14 dB between the  two pictures. An aircraft flying over the clutter in the first 5 mi in the left-hand picture  could not be detected, no matter how large its radar cross section. 
 By 1943 the R.3039 series wasconsidered obsolete. There was a further subdivision between receivers designed by Pye Radio and E K Cole. The receivers consisted of two stages of RF ampli ﬁcation, a local oscillator, a mixer, three stages of IF ampli ﬁcation, a detector and two stages of video ampli ﬁcation. 
  "EL    
 Near the scene center, the image  corresponds to the projection of the ground onto a slant plane ; this plane is determined  by the LOS and its perpendicular in the ground plane. We often refer to this type of  image as a slant-plane image . By appropriate interpolation and resampling, a ground- plane image  with dg = constant = dcr may be produced. 
 AP-19.pp.462-468. July,1971. 40.Loomis. 
 LENS REFLECTORS ARE USED FOR MAKING STRONG RADAR TARGETS OF SMALL VESSELS  AND THEY MAY BE OBTAINED  &)'52%     #7 
 105.  28. Lawson. 
 A 3D radar that obtains only one pillse per bcani position cart s~ffer  a relatively large beam-shape loss. Generally 2 or 3 pulses are required ys a minimum to  reduce this loss. Also,one plllse pcr beam - position dous~xo~.all~I-M~ processing* / makes difficult the accurate measurement of elevation angle. 
 N.. V. H. 
 dim. AppL MeteoroL, vol. 22, pp. 
 ERATION )N THIS TECHNIQUE  A DIGITAL COMPLEX BASEBAND WAVEFORM  USUALLY READ FROM A MEMORY  IS FIRST INTERPOLATED TO A HIGHER SAMPLE RATE  AND THEN MODULATED WITH DIGITIZED SINE AND COSINE SIGNALS TO PRODUCE A MODULATED CARRIER &IGURE  PROVIDES A BLOCK DIAGRAM OF A $5# THAT TRANSLATES A COMPLEX BASEBAND SIGNAL UP TO A  -(Z )& 4HE BASEBAND ) AND 1 SIGNALS ENTER THE $5# AT A RATE OF  -#303 AND ARE FIRST UP 
 INDEXED TABLE OF  PROPAGATION AND NOISE PARAMETERS IS COMPILED 0ARAMETER SELECTIONS ARE MADE ON THE BASIS OF THE BEST 3.2 IN EACH NOMINAL  
 The radar  olwratrd at ,i' harid will1 a 7-ft-diarnetcr arltenna arid a pulse width of 3  nanosecond^.^^  TRACKING RADARlSI mcasured bythcradarisohlaincd artcrcorrcction ismadcforthcJincrcncc inatmosphcric refraction foropticalandRFpropagatiDn. Thistypeofdynamic calibration requires the radar tobclargccnoughtotracksatcllitcs. Thercisnothing uniqucaboutanyoftheindividual processes thatenterintoon-axis tracking. 
 This gives a false-alarm probability of 1.1 1 x lo-'. Figure 2.7  indicates that a signal-to-noise ratio of 13.1 dB is required to yield a 0.50 probability of  detection, 14.7 dB for 0.90, and 16.5 dB for 0.999.  There are several interesting facts illustrated by Fig. 
 The forward-scatter RCS of more complex bodies has been simulated and mea - sured; the bodies were both reflecting and absorbing.67,70,71,76,82,84–86 Figure 23.8 shows a  method-of-moments simulation of a 16- by 1.85-cm cylinder with 992 facets at 35 GHz,  for three fixed transmitter-to-target geometries: ( a) near end on, ( b) 45° aspect angle,  and ( c) broadside.84 All three bistatic regions are shown in the figure. In the broadside  geometry, the pseudo-monostatic region occurs at b < 20°, bistatic at 20 ° < b < 140°,  and forward scatter at b > 140°. The other two geometries show a similar but broader  forward-scatter lobe, as is expected since the silhouette area and hence the shadowing  aperture are smaller. 
 BAND PHASED ARRAY RADAR v PRE 
 POWER 2& ! DIODE LIMITER CAN BE USED INSTEAD OF OR IN CONJUNCTION WITH THE GAS DISCHARGE TUBE 4HE 20 CAN BE REFLECTIVE OR ABSORPTIVE  BUT MUST HAVE LOW INSERTION LOSS TO MINIMIZE IMPACT ON RECEIVE CHAIN NOISE FIGURE #LUTTER !UTOMATIC 'AIN #ONTROL #!'#   4HE #!'# ATTENUATOR IS  USED BOTH FOR  SUPPRESSING TRANSMITTER LEAKAGE FROM THE 20 INTO THE RECEIVER SO THE RECEIVER IS NOT DRIVEN INTO SATURATION  WHICH COULD LENGTHEN RECOVERY TIME AFTER THE TRANSMITTER IS TURNED OFF  AND FOR CONTROLLING THE INPUT SIGNAL LEVELS INTO THE RECEIVER 4HE RECEIVED LEVELS ARE KEPT BELOW SATURATION LEVELS  TYPICALLY WITH A CLUTTER !'# IN SEARCH AND A TARGET !'# IN SINGLE 
 This equation can be used to measure the reflectivity factor Z when the antenna  beam is filled, when the small scattering particle Rayleigh approximation is valid, and  when the scatterers are in either the ice or the water phase. Because all these condi - tions are not always satisfied, it is common to use the term Ze, the effective reflectivity  factor, in place of Z. When Ze is used, it is generally understood that the above condi - tions are assumed. 
 R. L. Easton and J. 
 11 Fading for successive pulses  of a moving radar with ground target ch16.indd   18 12/19/07   4:55:25 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 BASED RADARS MAY BE CONSTRAINED BY COST AND SITING CONSIDERATIONS 3EVERE STORM WARNING RADARS REQUIRE LONG RANGE  AND HIGH UNAMBIGU 
 53. Lunehitrg. R. 
 The P1 and P2 codes are modified versions of  the Frank code with the DC frequency term at the center of the pulse instead of at the  beginning. They are more tolerant of receiver band-limiting prior to pulse compression  encountered in digital radar systems. The P1 codes contains M 2 elements as does the  Frank code, but the relationship of the ith element to the jth group is expressed as35  φ πi j M M j j M i, ( / )[ ( )][( ) ( )] = − − − − + − 2 1 1 1  (8.19) where i and j are integers ranging from 1 to M. 
 INFRARED SCANNERS PRODUCE STRIP IMAGES LIKE THOSE OF RADARS  BUT WITH DIFFER 
 1994 ,42, 1540–1545. [ CrossRef ] 23. Li, W.; Yang, J.; Huang, Y. 
 Geosci. Remote. Sens. 
 Radar rangesmightbeasshortasthatofthepoiice traffic-speed-meter, oraslongasthedistances to thenearbyplanets. Almostallradarsutilizedirective antennas. Adirective antenna notonlyprovides the transmitting gainandreceiving aperture neededfordetecting weaksignals,butitsnarrow beamwidth allowsthetarget'sdirection tobedetermined. 
 A. Stratton, Electromagnetic Theory , New York: McGraw-Hill Book Company, 1941,   pp. 414–420, 563–567. 
 Thus the improvement obtained with optimal weights as compared with  binomial weights is relatively small. This applies over a wide range of clutter spectral widths.  Similarly, it is found that the use of a criterion which maximizes the clutter attenuation (ratio  of input clutter power to the output clutter power) is also well approximated by a transversal  filter with binomial weights of alternating sign when the clutter spectrum can be represented  hy a gaussian function whose spectral width is small compared to the pulse repetition  frequency. 
 This we call the afterglow, and although it  can be a nuisance in television, it provides the answer to  many operational problems of radar.  Cadmium and calcium tungstate have a very short  - afterglow—in fact, the spot dies within about 7 micro-~  seconds (seven-millionths of a second) after fluorescence.  Zinc silicate has an afterglow of about 8 milliseconds  (eight-thousandths of a second); while right at the  other end of the scale is the ‘red screen,’ composed of  zinc phosphate, which gives a glow lasting for nearly  . 
 13. Scliellirlg. J. 
 A numerical evaluation of some of these performance parameters can be found in the literature.21'24 The SLB design requires the selection of suitable values for the following parameters: (1) the gain margin p and then the gain w of the auxiliary antenna, (2) the blanking threshold F9 and the normalized detection threshold a. The a priori known parameters are the radar sidelobe level G^/ and the values of SNR and JNR. The design parameters can be selected by trying to maximize the detection probability P0 while keeping at prescribed values the probabilities PB and PFA and trying to minimize PFT9 PTB9 and L. 
 The early radarswere dif ﬁcult to use and maintain and required special training of the operators and maintainers. Tactical operating techniques also needed to be developed. RAF Coastal Command set up a training and evaluation unit, the Coastal Command Development Unit (CCDU), at Carew Cheriton in December 1940. 
           . Óx°{  2!$!2 (!.$"//+  .OTE THAT THE LIGHTLY SHADED NEGATIVE 
 In Figure 9.31 a, the typical gaussian-like glint error  distribution is observed. With the wider separation of the aircraft, the tracking-error Component Bias Noise Radar-dependent    tracking errorsZero range setting Range discriminator shift    servo unbalance Receiver delayReceiver thermal noise Multipath Servo electrical noise Servo mechanical noise Variation in receiver delay Radar-dependent    translation errors Range oscillator frequency  Data takeoff zero settingRange resolver error Internal jitter Data gear nonlinearity and backlash Data takeoff nonlinearity and granularity Range oscillator instability Target-dependent    tracking errorsDynamic lag Beacon delayDynamic lag Glint Scintillation Beacon jitter Propagation error Average tropospheric refraction Irregularities in tropospheric refraction Average ionospheric refraction Irregularities in ionospheric refraction * From D. K. 
 BASED 3!2S OWE THEIR LARGE MODE VARIETY TO ACTIVE ELECTRONIC 
 The knowledge onwhich tobase the selection may beavailable apriori, oritmay depend partly onamemory ofwhat hashappened inthe immediate past. Asanexample ofsuch methods consider aninformation-bearing pulse. Very similar pulses with the same frequency components asthe signals are likely tobepresent inthe interference and ofcourse cannot be. 
 Geosci. Remote Sens. 1992 ,30, 412–415. 
 Haykin, “Radar clutter attractor: implications for physics, signal processing and control,”   IEE Proc. Radar: Sonar Navig ., vol. 146, no. 
 To summarize the general utility of 6 dB definitions: (1) The range equation for detection in noise need not include peak power, pulse width, or receiver bandwidth; only the efficiency of the integrator requires a definition of the num- ber of pulses being received, and a 6 dB echo definition is universally employed. (2) The optimum bandwidth is close to the inverse of the echo duration if both are 6 dB definitions; this applies to both the receiver filter and the integrator. (3) The energy of the interference from clutter, rain or chaff, that is accepted by an ap- proximately matched receiver is well defined by the 6 dB pulse duration and 6 dB two-way beamwidth. 
 FREQUENCY(GHz) (a) FREQUENCY (GHz) (b) FIG. 12.26 Regressions for vertical-polarization clutter model for snow: (a) day and (b) night. Note the large differences. 
 LAP THE SAMPLED SIGNAL IS NOT ALIASED !S WILL BE DESCRIBED IN MORE DETAIL LATER IN THE CHAPTER  THIS TECHNIQUE   BANDPASS SAMPLING  IS A POWERFUL TOOL THAT ALLOWS A RELATIVELY  HIGH 
 BAND INTERFERENCE AND DIGITIZE THE RECEIVED SIGNAL WITH THE MINIMUM OF ERROR SO THAT OPTIMUM FILTERING CAN BE PERFORMED USING DIGITAL  SIGNAL PROCESSING -ATCHED  &ILTERING  !LTHOUGH MATCHED FILTERING IS TYPICALLY NOW PERFORMED  WITHIN THE DIGITAL SIGNAL 
 Rt>eord, vol. 2, pt. I. 
 Theechofromforestsdiffersdepending ontheseason.Bycontrast. sea echoismoreuniform overtheoceansoftheworld.providing thewindconditions arethe same.Although knowledge ofseaclutterisfarfromcomplete. itisbetterunderstood thanis theknowledge oflandclutter. 
 The- oretically, thehigh-frequency response---------L, c Rwould bemaintained, however large C,bymaking Rproportionally smaller. IfRistoosmall, however, the detec-S+= FIG. 12.9.—Diode detector.tion efficiency islowered and themax- imum voltage that the detector can produce becomes too low. 
 Sequential detection hasalsobeenusedtodescribe atwo-step, ortwo-stage, detection process. 382 INTRODUCTION TO RADAR SYSTEMS  that can be employed with phased-array radar.39*42 The radar transmits a pulse or a series of  pulses in a particular direction as in an ordinary radar, except that the false alarm probability  is slightly higher than would normally be used. If no threshold crossings are obtained, the  antenna beam moves to the next angular position. 
 All phase information is destroyed. It is  also possible to design a detector which utilizes only phase information for recognizing targets.  An example is one which counts the zero crossings of the received waveform. 
 V . Mrstik, “The Kiernan reentry  measurements system on Kwajalein Atoll,” The Lincoln Laboratory Technical Journal, vol. 2,   no. 
 119–123. 110. D. 
 FED CIRCULAR REFLECTOR WITH A  
 FIG. 20.7 Multiple-pulse vector monopulse processing.ANTENNATRANSMITTER SUMRECEIVERCOHERENTSIGNALPROCESSINGMAG7, THRESHOLD DELTARECEIVERCOHERENTSIGNALPROCESSINGReMONOPULSETABLEGATE . The fundamental accuracy performance of a pair of uniformly illuminated beams in a stack is presented in Fig. 
 The gain con - trol effectively alters the detection threshold. On a modern marine radar, the sea-clutter  control is best described as a method for adjusting the shape of the radar’s sensitivity  time control  (STC) in order to match it with the present level of clutter returns. STC is  often also called swept gain . 
 Waterman. A. T.. 
 The letter Z is for equipment in a combination of airborne instal- lations, such as aircraft, drones, and guided missiles. The equipment indicator letter (second column of Table 1.2) that designates radar is the letter P; but it is also used for beacons which function with a radar, electronic recognition and identification systems, and pulse-type navigation equipment. Canadian, Australian, New Zealand, and United Kingdom electronic equip- ment can also be covered by the JETDS designations. 
 Large convoys could be detected at ranges doi:10.1088/978-1-6432-7066-1ch7 7-1 ªMorgan & Claypool Publishers 2018. of up to 40 miles from a height of 500 ft (i.e. well beyond the radar horizon, which would have been about 27 nautical miles at 500 ft). 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Airborne MTI. 3.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3  9. 
 69. National Research Council, Weather Radar Technology beyond Nexrad , Washington, DC: National  Academy Press, 2002. 70. 
 MTl AND PULSE DOPPLER RADAR 143  Based on an analysis of antenna radiation patterns and experimental data, Staudaher58 gives  the standard deviation of the clutter spectrum due to platform motion as  '1pm ::::::0: 0.6 Vx a (4.37)  where vx is the horizontal component of the velocity perpendicular to the antenna pointing­ direction and a is the effective horizontal aperture width. The antenna beamwidth is assumed  to be approximated by 08 = },_/a. [Equation ( 4.3 7) is not inconsistent with the simpJe derivation  of Eq. 
 Arelated problem isthis: Suppose that onasingle radar indicator wesimply remove the signal from alternate sweeps (by holding offthe transmitter pulse, forexample). The resulting increase inStin will amount toabout 3dbinthis case, forwhat wehave done is equivalent tothefollowing twochanges; (1)reduction inPRF byfactor of~with corresponding reduction inn;;(2)mixing inanequal number of foreign noise-bearing sweeps, asintheprevious example. Whether the detector isasquare-law detector, alinear detector, or something else, will nodoubt influence S~i. 
 However, a nonlinear phase distribution is required across the planar array of  the dome antenna. The beamwidth can vary on the order of 4 to 1 over the entire scan range of  the dome afitenna. Furthermore, the beam might not be as narrow on the horizon as might be  obtained with a conventional antenna configuration of equivalent aperture. 
 (13.8) would not apply.  The antenna gain does not enter, except as fr is affected by the azimuth beam width 08.  The narrower the pulse width the greater the range. 
 1805 , September 1999. 76. S. 
  +1 
 SHAPED TARGET AND IS READILY VISUALIZED AS THE FLUCTUATING SUM OF MANY SMALL VECTORS CHANGING RANDOMLY IN RELATIVE PHASE !LTHOUGH IT IS CALLED  NOISE  IT MAY INCLUDE PERIODIC COMPO 
 B. Sailors, “Discrepancy in the International Radio Consultative Committee Report 322-3  radio noise model: The probable cause,” Radio Science , vol. 30, pp. 
 Many of the civilian applications of radar are also employed by the military. The  traditional role of radar for military application has been for surveillance, navigation, and  for the control and guidance of weapons. It represents, by far, the largest use of radar. 
 C.. F. 1%. 
 Dependence on Wind Speed and Direction.  Experimentally, the relation  between sea clutter and wind speed is complex and uncertain, it having been found  to depend on almost all of the parameters that characterize sea clutter: frequency,  grazing angle, polarization, the state of the sea surface, the direction and speed of  the wind itself, and even on whether the measurements are made from an aircraft or  a tower platform.36 A common way to organize clutter data is to seek the best straight-line fit (linear  regression) between clutter cross sections in decibels and the log of the wind speed  (or some other parameter). This, of course, imposes  a power-law relation between  the variables: s  0 ∼ Un, where n is determined by the slope of the line. 
 Radar beacons operate onadifferent principle. A receiving antenna ataremote point picks updirectly energy sent out from the radar transmitter. The signal isamplified and enabled to initiate the transmission ofanother signal, inreply, byanassociated transmitter. 
 H. Y . Lee, J. 
 A separate receiver is  required for each of the simultaneous beams. ne elevatj-&MY-of~fstngie-~~~~~j~n~t~eam -..- 3D radars -. is ~lsually less than that  of other systems. 
 BASED ANGLE OF ARRIVAL MEASUREMENT -ONOPULSE ROTATING ANTENNAS CAN ALSO BE USED WHEN THE TIME TO INTERCEPT IS NOT CRITICAL THIS IS THE %,).4 CASE   AND IT IS POSSIBLE TO SCAN SEQUENTIALLY THE OPERATIONAL SCENARIO 4HE CARRIER FREQUENCY IS THE NEXT MOST IMPORTANT PULSE PARAMETER FOR DEINTERLEAV 
 Geosci. Remote Sens. 2002 ,40, 2375–2383. 
 The individual scatterers, which give rise to doppler  spread, are small and so recognition is usually limited to a fraction (1/2 typical) of  maximum range. Jet engine modulation (JEM), a subset of doppler signatures, is an  excellent target recognition method. Even aircraft, which use the same engine type,  often have variations in the engine application, such as the number of compressor  blades or number of engines, which allows unique type recognition. 
 3.3 BANDWIDTHCONSIDERATIONS Definitions. The instantaneous bandwidth of a component is the frequency band over which the component can simultaneously amplify two or more signals to within a specified gain (and sometimes phase) tolerance. The tuning range is the frequency band over which the component may operate without degrading the specified performance if suitable electrical or mechanical controls are adjusted. 
 Hannan, “Microwave antennas derived from the cassegrain telescope,” IRE Trans .,  vol. AP-9, pp. 140–153, March 1961. 
 Thenumber tilis thesecondthreshold tobepassedinthedouble-threshold detector. Thetwothresholds must beselected jointlyforbestperformance. Theoptimum valueofInforaconstant echosignalis showninFig.lOX(Similar resultsareavailable forfluctuating targets.39,58,59)Thiscurve isapproximate sincethereissomeslightdependence uponthefalse-alarm probability, butit appears tobeindependent ofthesignal-to-noise ratio.Theactualvalueofmcandiffer signiticantly fmlllmoplwithollt alargepenalty insignal-to-noise ratio.Forexample. 
 This is achieved by a feeding network, which allows a specific influence of  the phase and/or the amplitude for each individual element and/or sub -array of the entire array.   With the appe aring monostatic Radar devices, since the same antenna groups for transmitting  and receiving are predominantly used, the transmitting and receiving paths must be additio n- ally separately switchable.  The named functions are made available by the so -called T rans- mit/Receive (T/R) modules, which are embedded into the system according to Figure 13.26. 
 So Debiased-CS and LS-CS-Residual avoid the underestimation caused by CS. In Figure 3Area 2, CS and debiased-CS fail in reconstructing the weak scattering. Since the support information of the other subapertures is adopted in LS-CS-Residual, the support of weak scattering target is preserved in the subapertures. 
 Weather echoes are a nuisance to the  radar operator whose job is to detect aircraft or ship targets. Echoes from a storm, for  example, might mask or confuse the echoes from targets located at the samt! range and  azimuth. On the other hand, radar return from rain, snow, or hail is of considerable impor­ tance in meteorological research and weather prediction. 
 85.)  39. Sims, R. J., and E. 
 (I 1.16) was first introduceti by Gabor4 atid Ii:ts  heen used by Woodwards iri his treatnient of detection and accuracy by means of inverse  probability. 13otli Ci:tt~or nricl Wootiwarti defirie the effective bandwidth in ternis of tile  co~iiplex-frequency represeri tat ion, while the definition presented above is in terms of the real  tirne waveft>r~ris. In essence, p2 is the riorr~ialized second mornent of the spectrum IS(f )I2  :~btrut tile tne;lri (Iicre take11 to be at zero frequency). 
 The smaller xand the larger h,,the more finely divided isthe lobe pattern. A welcome change, ontheother hand, istheadditional factor of16,effective inEq. (29) fordirections ofmaximum constructive interference. 
 SIZE DISTRIBUTION  IS GIVEN AS   .$    . $L E n,$   WITH L   n AND  ,$      L 4HE L PARAMETER CONTROLS THE SHAPE OF THE DISTRIBUTION  AND WHEN L     THE DISTRIBUTION IS EXPONENTIAL #LEARLY  A SINGLE 
  
 ICE WAS PREDICTED MANY YEARS AGO TO HAVE ACCUMULATED OVER SOME TWO BILLION  YEARS IN THE FLOOR OF LUNAR CRATERS OR OTHER FEATURES WHOSE DEPTH AND LATITUDE KEPT THEM IN PERMANENT SOLAR SHADOW 4HE ONLY SOURCE OF HEAT FOR THOSE REGIONS WOULD BE BACK 
 ##     $&   $#  "  %$    
 10.10~) whose delay is equal to the pulse repetition period. The recirclrlatiny-  Topped deloy line  Video in  output  Figure 10.9 Pulse integrator using tapped delay line.  390INTRODUCTION TORADAR SYSTEMS Suchclutterischaracterized byhavinglarge"spiky"echoes.Although theymayoccur in~ frequently, theycanbequitelargeandgiveundueweightinaconventional integrator. 
 PLING PERIOD IS SELECTED AS FOLLOWS 
 AXIS TRACKING WITH A MECHANICAL 
 A., and V. N. Bringi: Potential Use of Radar Differential Reflectivity Mea- surements at Orthogonal Polarizations for Measuring Precipitation, J. 
                             
 AIRBORNE MTI  3.276x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 3 freedom in STAP while still processing the full aperture spatially. This is similar to  a conventional MTI (or DPCA) architecture cascaded with doppler filtering. We call  this architecture a pre-doppler, elemental-level STAP architecture. 
 The Nexrad long-range weather sur - veillance radars are frequently supplemented by (typically) smaller medium-range weather  radars operated by TV stations for local observations.8 In addition to the familiar com - mercial airborne weather avoidance and observation radars, airborne hurricane monitoring  provides detailed forecasts and warnings for approaching coastal hurricanes.9 And verti - cal pointing wind profiling fixed-beam systems are routinely used to obtain continuous  profiles of horizontal winds10 whereas spaced-based meteorological radars are measuring  widespread equatorial precipitation fields and cloud properties.11 Meteorological research  results are regularly transferred to the operational weather radar community for achiev - ing higher space and time resolution, for improved data quality, and for the production of  new weather radar products all of which have led to dramatic improvements in weather  forecasting. Doppler weather radars measure detailed vector wind fields as well as precipi - tation fields. Small, highly mobile research radars provide many of the same capabilities  as the fixed radars.12 Dual polarization techniques13,14 are used for improved quantitative Chapter 19 * The National Center for Atmospheric Research is sponsored by the National Science Foundation. 
 EMITTER DELAY TIME )F A SIGNAL IS INTRODUCED TO E ITHER THE BASE OR THE EMIT 
 RANGE TARGET IMAGE INFORMATION   °Ê "/ 
 parameters needed to describe the SLB performance, the last figure to consider is the detection loss L on the main-beam target. This can be found by comparing the SNR values required to achieve a specified PD value for the radar system with and without the SLB. L is a function of many parameters such as P0, PFA9 F9 GA9 JNR9 and p. 
 SION 4HESE AND OTHERS ARE DISCUSSED NEXT 4HE USE OF THE DOPPLER FREQUENCY SHIFT TO DETECT MOVING TARGETS IN THE MIDST OF  LARGE CLUTTER ECHOES REQUIRES THAT THE TRANSMITTER PRODUCE A STABLE SIGNAL WITH LITTLE EXTRANEOUS NOISE "ECAUSE OF THEIR POOR STABILITY AND NOISY TRANSMISSIONS  MAGNETRONS ARE LIMITED IN THE AMOUNT OF -4) )MPROVEMENT &ACTOR THEY CAN ACHIEVE TO ABOUT  OR PERHAPS  D" -ANY RADAR APPLICATIONS REQUIRE GREATER -4) )MPROVEMENT &ACTORS 3OME RADARS ALSO REQUIRE THE USE OF PULSE 
 The other cure forthe deck-tilt error istodrive the azimuth sweep ofthe radar indicator ata constant rate during search and tocontrol thetrain angle oftheantenna bymeans ofacomputer and servomechanism. Aswehave seen, itisone ofthe functions ofthe computer toprovide the deck-tilt correction. This computation iseasily mechanized, because the deck-tilt error is mathematically similar tothe error intransmitting angular motion through auniversal joint. 
 £°£n  2!$!2 (!.$"//+  IS  -7 AT 3 BAND AND  +7 AT +A BAND 4HE PULSE WIDTHS ARE APPROXIMATELY   MS   4HE 02& IS TYPICALLY  Sn AT 3 BAND AND A FEW TIMES LARGER AT +A BAND 4HIS  RADAR SYSTEM IS CHARACTERISTIC OF THE TECHNOLOGIES CURRENTLY IN PLACE IN THE RESEARCH   COMMUNITY 0OLARIMETRIC 2ADAR  -ETEOROLOGICAL RADARS USING DUAL POLARIZATION TRANSMIT AND  RECEIVE BOTH HORIZONTAL AND VERTICAL POLARIZATIONS TO ESTIMATE ADDITIONAL CHARACTERIS 
 LOOP TRACKING SIMILAR TO THE ANGLE TRACKER %RROR IN CENTERING THE RANGE GATE ON THE TARGET ECHO PULSE IS SENSED  ERROR VOLTAGES ARE GENERATED  AND CIRCUITRY IS PROVIDED TO RESPOND TO THE ERROR VOLTAGE BY CAUSING THE GATE TO MOVE IN A DIRECTION TO RECENTER ON THE TARGET ECHO PULSE 4HE RANGE 
 Radiations from nearby transmitters m!ly therefore damage the receiver without firing the TR.  To protect the receiver under these conditions, a mechanical shutter can be used to short­ circuit the input to the receiver whenever the radar is not operating. The shutter might be  designed to attenuate a signal by 25 to 50 dB. 
 For instance, the JORN radars exploit approximately 20 sounders and related facilities  distributed around the coast of Australia. Radar performance in most operational roles  is governed by the fidelity of the adopted RTIM. It is important to differentiate between models that describe the physical (or  physico-chemical) state of the ionosphere and models that describe radiowave propa - gation characteristics, though the latter are often derived from the former by apply - ing ray-tracing methods, and the former are predominantly derived from radiowave  propagation measurements such as point-to-point link statistics and vertical incidence  soundings. 
 In conclusion, these devices have a place in the radar but not as means for  fighting the ECM battle. In summary, there isn’t much that has been done in the receiver to combat ECM  other than to insure there is a good receiver that does its job. Today, modern phased- array multi-channel radar are going to adopt fully digital, software controlled receivers,  as in the DAR case; here, the expected advantages are the wider linear dynamic range  and the within-band calibration of the receivers that will support the adaptivity on sev - eral tens of channels: a distinctive advantage against directional noise jammers. 
 In thisbasic radar system, the type of display used is the PLAN POSITIONINDICATOR (PPI), which is essentially a polar diagram, with thetransmitting ship’s position at the center. Images of target echoes arereceived and displayed at either their relative or true bearings, and at theirdistancesfromthePPIcenter.Withacontinuousdisplayoftheimagesofthetargets,themotionofthetargetrelativetothemotionofthetransmittingshipis also displayed. The secondary function of the indicator is to provide the means for operating various controls of the radar system. 
  . 
 DISTRIBUTION  THAT  ALTHOUGH SOME 
 If the ap- proximate forms for R-R' as given by the approximate expressions in Eqs. FIG. 21.4 Geometry for Eqs. 
 Probability of False Alarm. PD radars often employ a multilook detection criterion to resolve range ambiguities such that during the time on target (dwell time) several PRFs are transmitted in successive looks and a threshold detection in more than one look is required for the radar to output a target report. For the case where a doppler filter bank in each range gate is used for coherent integration, possibly followed by a postdetection integrator, the probability of false alarm PFA in each range gate-doppler filter required to obtain a given false report time TFR is given approximately by 1 T 0.693 Td V/»' ^FA = TH- — (17-22) MOS)"* Vl where NF = number of independent doppler filters visible in the doppler passband (number of unblanked filters/FFT weighting factor) n = number of looks in a dwell time /77 = number of detections required for a target report (For example, 3 detections out of 8 PRFs is m - 3 and n = 8.) Td - total dwell time of the multiple PRFs including postdetection inte- gration (if any) and any dead time (jln) = binomial coefficient n\l[m\(n - m)\]LOSS (dB) . 
 With a nonreciprocal phase shifter, it is necessary to switch the  phase shifter (i.e., change phase state) between transmit and receive. Typically, it takes  a few microseconds to switch nonreciprocal ferrite phase shifters. During this time, the  radar is unable to detect targets. 
 A6H6 diode second detector iscapacitively coupled into asingle video stage. The video stage serves asacombined line driver and limiter. It ~perates asacathode follower, the cathode resistance of100 ohms being located attheend ofthevideo line. 
 VERSUS 
 BEAM JAMMING AND ALSO PROVIDES A STROBE IN THE DIRECTION OF THE JAMMER 3TROBES FROM A FEW SPATIALLY SEPARATED RADARS ALLOW THE JAMMER TO BE LOCATED 4HE AVAILABILITY OF SOLID 
 The characters and symbols that constitute the synthetic information may be inserted  on a CRT during the radar dead time at the end of the sweep prior to the triggering of the  next pulse. In some situations there might be too much information to be fully inserted  during the available dead time. In a long-range air-traffic-control radar located in a busy area  there might be more than a hundred targets for display extracted. 
 ,-* 
 S. A.: A. Mathematical Theory of Linear Arrays, Bell Systen~ Tech. 
 This slight difference indoppler frequencies leads toaphase difference between the two doppler-frequency outputs which isalinear function oftime, just asthe target range isalinear function oftime forconstant radial velocity. This suggests that the phase difference isameasure ofthe range. This isinfact thecase, asmay beshown analytically, orqualitatively bythe following argument. 
 Thus the effect of platforrn velocity can be considered as liaving two components. One is  iri the direction of anteiina poiutitig and shifts the center frequency of the clutter doppler  spectrum. The other is rlor~nal to tlle direction of antenna pointing and results in a widening of  the clutter doppler spectrum. 
 17.5 KEY ASPECTS OF SAR Range and Velocity Contours.  Using fine range resolution, a radar can distin - guish between targets at different ranges. A particular target may be determined to  be located on a constant-range-contour. 
 TION OF WEIGHTS  SUCH AS (ANNING AND (AMMING WEIGHTS  WHICH BROADEN THE MAIN LOBE RESPONSE OF THE $&4 OUTPUT  BUT REDUCE THE AMPLITUDE OF THE SIDE LOBES ! THOROUGH TREATMENT OF $&4 WEIGHTING FUNCTIONS AND THEIR EFFECTS IS GIVEN BY (ARRIS . 
 Tile rno<lulati11g ano<le, or other beam control electrode, is often included as part ol'  the electron-gun structure to provide a means for pulsing the electron beam on and off. The  RI· cavities. which correspond to the LC resonant circuits of lower-frequency amplifiers. 
 Insuch acase, some oftherequire- ments inthetable could berelaxed considerably. TAZLE 161.—STABILITY REQUIREMENTS FOR HIGH-PERFORMANCE SYSTEM WITII PRF OF1000 PPS, PULSE LENGTFI 1ASEC, GROUND CLUITER OUT TO50}’lILES Component Quantity Stable localoscillator, Frequency drift Coherent oscillator. Frequency drift Magnetron ........ 
 Blake, L. V.: Prediction of Radar Range, chap. 2 of" Radar Handbook," M. 
 ON PROGRAM  THE 'LOBAL 0RECIPITATION -EASUREMENT '0-  PROGRAM  ENVISIONS EXTENDING PRECIPITATION COVERAGE TO THE MID 
 360-367, July, 1960.  76. Oliner, A. 
 Peters: Weibull Distribution Applies to Sea Clutter, Itrtrrnariotral  Conference RADAR-77, pp. 101-104, IEE Conference Publication no. 155. 
 It is of interest to note that in many of the reported measurements of sea clutter, particularly in the older literature, wide inconsistencies between wind speed and waveheight may be found. For example, a wind speed of 5 kn might be reported with waveheights of 6 ft, or 20-kn winds with 2-ft waves. These pairings are in- consistent with the values for an equilibrium sea described in Table 13.1 and in- dicate the unnoticed presence of heavy swell or highly nonequilibrium wind con- ditions, or both. 
 STATE VALUE UNTIL SPACE CHARGING IS COMPLETE 3OME SETTLING TIME MUST BE ALLOWED BEFORE SIGNALS ARE PASSED TO THE FILTER BANK 4HEREFORE  THE COHERENT INTEGRA 
 Probably the most prominent source of angels is birds. Although the radar cross section  of a single bird is small compared with that of an ordinary aircraft, the backscatter echo from a  bird can be readily detected by many radars, especially at the shorter ranges, because of the  inverse-fourth-power variation of echo signal with range. If, for example, the cross section of a  bird the size of a sea gull were 0.01 m2, it would produce as large an echo signal at a range of  10 nmi as would a 100 m2 radar cross-section target at 100 nmi. 
 BASED RADAR WOULD BE ABLE TO DETECT WITH A CERTAIN PROBABILITY OF DETECTION  A PARTICULAR AIRCRAFT TARGET !N OPTIONAL CAPABILITY OF !2%03 IS TO PROVIDE TO AN EXTERNAL APPLICATION  THE COM 
 ENCE BETWEEN DAY AND NIGHT SCATTER FROM SNOW IS EVEN MORE PRONOUNCED AT  '(Z  BUT THE MODEL DOES NOT INCLUDE  '(Z BECAUSE NO DATA EXISTS BETWEEN  AND  '(Z !LTHOUGH  NO  SPECIFIC  CLUTTER  MODEL HAS BEEN DEVELOPED FOR FORESTS  RESULTS FROM THE 3KYLAB 2!$3#!4 AND  3EASAT  SCATTEROMETER  SHOW THAT THE !MAZON RAINFOREST SCATTERS ALMOST INDEPENDENTLY OF THE ANGLE OF INCIDENCE EVEN NEAR VERTICAL   4HE MEAN MEASURED VALUE AT  WAS  
 J.: Arrival Time Estimation by Adaptive Thresholding, IEEE Trans., vol. AES-10, pp.  178-184, March, 197 4. 
 F. Moody. P. 
 Maine.  Air-supported radomes have a number of disadvantages. Their life is limited by exposure  to ultraviolet liplit. 
 SIGNAL-TO-NOISE RATIO (SNR) IN MAIN CHANNEL, dB FIG. 17.9 Probability of detection versus signal-to-noise ratio with a guard channel. FIG. 
 O X v A CY BP Side-looking beam Backward-looking beam Forward-looking beam Figure 1. Model of multi-angle SAR imaging system. 2.1. 
 SIZE DISTRIBUTIONS  DESCRIBING  THE -ARSHALL 
 L. Maffett, and R. A. 
 E. Andreta (SELEX Sistemi Integrati, Italy),  Dr. G. 
 BIT PHASE SHIFTING 3WITCHED 
 Trizna, D. B., J. C. 
 (ILL     3EC   h0ULSE MODULATORSv  4 ! 7EIL  h4RANSMITTERS v #HAP  IN  2ADAR (ANDBOOK  ND %D  .EW 9ORK -C'RAW 
 A different sequence is obtained with different feedback connections. (The  number of stages connected modulo two must be even since an odd number of modulo-two  additions taken from the all-ones state will produce a one for the next term and the continued  generation of the all-ones state. This generates a sequence of length 2" - 2 and is not an  m-sequence.57) Table 11.3 lists the number of possible m-sequences obtainable from an  11-st age shift register. 
 24.14 Plasma-frequency contours are given, extending from the radar to a point east 3000 nmi downrange; January day example. Figure 24.15 shows a performance prediction in the form of an oblique sound- ing. A typical sky-wave radar will be equipped with a vertical sounder and an oblique backscatter sounder for transmission-path analysis and to aid in radar- frequency management. 
 SCALE  CHANGES IN THE IONOSPHERE 4YPICALLY  THIS IS OF THE ORDER OF n MINUTES 4RANSMISSION 
 WIDEBAND  2ADAR  -EASUREMENTS  3YSTEMS  )%% 2ADAR 3ONAR  .AVIGATION AND !VIONICS 3ERIES  6OL   ,ONDON )%% "OOKS    #HAP   - 4 4ULEY  * - 2ALSTON  & 3 2OTONDO  ! - !NDREWS  AND !% - 2OSEN  h%VALUATION  OF %ARTH2ADAR UNEXPLODED ORDNANCE TESTING AT &ORT !0 (ILL  6IRGINIA v  )%%% !EROSPACE AND  %LECTRONICS 3YSTEMS -AGAZINE  VOL   ISSUE   PP n  -AY   0 $EBYE   0OLAR -OLECULES  .EW 9ORK #HEMICAL #ATALOG #O    + 3 #OLE AND 2 3 #OLE  h$ISPERSION AND ABSORPTION IN DIELECTRICS  )  ALTERNATING CURRENT  CHARACTERISTICS v * 0HYS #HEM  VOL   PP n    $ * $ANIELS  h2ESOLUTION OF 57" SIGNALS v  )%% 0ROC 2ADAR 3ONAR AND .AVIGATION   VOL    PP n  !UGUST   # -ARTEL  - 0HILIPPAKIS  AND $ * $ANIELS  h4IME DOMAIN DESIGN OF A 4%- HORN ANTENNA FOR  '02 v PRESENTED AT -ILLENNIUM #ONFERENCE ON !NTENNAS AND 0ROPAGATION  !PRIL   $ * $ANIELS  h!N ASSESSMENT OF THE FUNDAMENTAL PERFORMANCE OF '02 AGAINST BURIED LAND 
 W. J. Ince, “Recent advances in diode and phase shifter technology for phased array radars,”   pts. 
 3URFACE (YPOTHESES  3INCE IT IS NOT CLEAR HOW TO EXTEND STRAIGHTFOR 
 BY 
 1.14  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 (with few exceptions) for airborne radar altimeters. There are no official ITU allocations  for radar in the HF band, but most HF radars share frequencies with other electromag - netic services. The letter-band designation for millimeter wave radars is mm, and there  are several frequency bands allocated to radar in this region, but they have not been  listed here. 
 Turbulent motion ischaracterized byavariable velocity fieldandthl'pn;scncc ofnOlllllllfor­ mities,oreddies,thatproduce mixing. Theatmosphere canbeassumed tobeturbulent everywhere, butitsintensity varieswidelybothinspaceandtime.Itisonlywhenturbulence is concentrated intoregionsofgreaterorlesserintensity thanitssurroundings thatitisof interestasanelectromagnetic scatterer. Thereareatleasttwotypesofturbulent atmospheric formations thatcanresultinangelactivity. 
 Land subsidence can lead to serious environmental problems and considerable economic losses, such as damage to Sensors 2019 ,19, 743; doi:10.3390/s19030743 www.mdpi.com/journal/sensors 213. Sensors 2019 ,19, 743 infrastructures and increased risk of urban pluvial ﬂooding [ 14–18]. Thus, the demand for monitoring the spatial and temporal distribution of land subsidence is increasing. 
 'Tlic system losses have been omitted. Tlie remaining syrn-  bols I\avc bcc11 dcfirietf i~bove 01- ill Sec. 2.14. 
 I. Skolnik (ed.),  McGraw-Hill Book Co., New York, 1970.  31. 
 RANGE (IGH RANGE RESOLUTION IS OFTEN OBTAINED USING PULSE COMPRESSION )NVERSE SYNTHETIC APERTURE RADAR )3!2   )3!2 IS A COHERENT IMAGING RADAR THAT USES  HIGH RESOLUTION IN RANGE AND THE RELATIVE MOTION OF THE TARGET  TO OBTAIN HIGH RESOLU 
 (From C. Cutl~~r,~ 1'1.o~.  IRE )  of a 0.841-diameter circular waveguide is shown in Fig. 
 Thus, it causes targets to be missed. Furthermore, the operator is usually  given no indication that there may be missed detections. In radars with a simple CFAR,  interference or hostile jamming can lower the sensitivity of the radar without the operator even  being aware that it is happening since the jamming is not visible on the scope. 
 The azimuth resulting from this operation iscompared with the instantaneous azimuth ofthe radar TrueN.Sfixknob Compassair speedrepeater — SpeedD4 ON-S rateknobAltitudeknob 1, &oundposition integrators for N-SandE-W components windconstant. speedspeed mechanism aE-Wrateknob .* Azimuth from E-Wfixknobradarscanner FIG.7.3.—Simplified schematic diagram ofGround Position Indicator. scanner. 
 Complexity The computational complexity (ﬂoating-point operation) of the EMAM method is analyzed in detail. For the signal at a certain range cell, the number of azimuth points is Na. The complexity of the main steps of the EMAM method is as shown in Table 1. 
 &- SLOPES ARE APPLIED TO LOOKS  THROUGH  M OF A M 
 END RADAR PROPAGATION ASSESSMENT TOOL "ECAUSE %- PROPAGATION EFFECTS ARE NOT JUST LIMITED TO RADAR FREQUENCIES  OVER TIME THE INITIAL RADAR REQUIREMENTS FOR !2%03 WERE EXPANDED BEYOND SIMPLE RADAR  DETECTION APPLI 
 Longer time constants are possible inthe second limiter since the signal variations atthk tube are neither large nor ofshort duration. This equipment has been given extensive airborne tests inconjunction with two different types ofsynchronization equipment, and hasalso been operated between fixed ground stations. 17.14. 
 The  principal advantage to MFR is that many deployed radars have multiple channels and  switching between them on a single target is relatively easy. A simplified version of  the recognition process is summarized in Figure 5.22. Doppler signatures require high doppler resolution, which is usually easily achieved  and limited only by dwell time. 
   05,3% $/00,%2 2!$!2   {°{£ WHEN THE RECEIVER IS BLANKED DURING PULSE TRANSMISSION )N A MULTIPLE RANGE GATE SYS 
 BER OF #0)S NONCOHERENTLY INTEGRATED .PDI   AND THE TARGET 2#3 FLUCTUATION MODEL  ASSUMED 4HE INVERSE PROBLEM OF DETERMINING THE REQUIRED 3.2 FOR A GIVEN  0D CAN BE  SOLVED VIA APPROXIMATIONS 5NIVERSAL DETECTION EQUATIONS HAVE BEEN PUBLISHED THAT  PROVIDE REASONABLY ACCURATE RESULTS AND ARE REPRODUCED HERE !GAIN  THE ASSUMPTION  THAT TARGETS ARE IN A GAUSSIAN NOISE 
 Equations 19.42–19.45 are applicable in high signal-to-noise ratio cases.  Uncertainties in the spectral moment estimates result from the limited observation  time of the narrow band random process characterizing the meteorological echo. Any  noise in the measurement further increases the uncertainty. 
 Thesolarnoisecansometimes beofsignificant magnitude toaffectthesensitivity oflow-noise radarreceivers fromenergyreceived intheantenna sidelobes. Thesunalsocanbeused asasourcetocalibrate thebeam-pointing (boresight) oflargeantennas.58Discrete radio sources, call&lradiostars,aretooweakatradarfrequencies tobeaserioussourceofinterfer­ ence,buttheyhavebeenusedinconjunction withsensitive receivers todetermine pointing and focusing corrections forlargeantennas.59 Systemnoisetemperature. Figure12.12illustrates someofthesourcesofnoisewhichgenerally mustbeconsidered whencomputing thesystemeffective noisetemperature. 
 TherlOnlinear-F Mwaveform withconstant-amplitude timeenvelope provides acom­ pressedwaveform withlowtime-sidelobes attheoutputofthereceivermatched-filter without the1-to2-d8penaltyobtained withthe.linear-FM waveform andmismatched filter.16.24.32 Thenonlinearvariation offrequency withtimehasthesameeffectasamplitude-weighting the transmitted-signal spectrum, whilemaintaining therectangular pulse-shape desired for efficient transmitter operation. Ifthenonlinear FMissymmetrical intime,theambiguity diagram hasasinglepeakratherthanaridge.(Asymmetrical waveform meansthefrequency increases, ordecreases, duringthefirsthalfofthepulseanddecreases, orincreases, duringthe secondhalf.)Thenonlinear FMisthusmoresensitive todoppler-frequency shiftsandisnot doppler-tolerant. Thesurface-acoustic-wave delaylineisonemethodforgenerating thenon­ linearFMwaveform andforactingasthematched filter. 
 GATION CHARACTERISTICS  THOUGH THE LATTER ARE OFTEN DERIVED FROM THE FORMER BY APPLY 
 RANGE NOISE AT THE LOWER FREQUENCIES AND BY THERE BEING FEW OR NO SKYWAVE PATHS TO NOISE TERRESTRIAL SOURCES AT THE HIGHER FREQUENCIES AT NIGHT )N GENERAL  NIGHTTIME NOISE WILL BE GREATER THAN DAYTIME NOISE FOR SKYWAVE ILLUMINATION OF A SELECTED RANGE 4HIS IS EVIDENT IN &IGURE   RECORDED AT TIME ZONE 54       4HE GENERAL TRENDS OF ATMOSPHERIC NOISE IN OTHER SEASONS ARE SIMILAR TO THOSE IN WINTER (OWEVER  THERE CAN BE LARGE DIFFERENCES IN LEVELS AT OTHER LOCATIONS ON THE %ARTH &OR MORE DETAILED ANALYSIS AND SYSTEM OPTIMIZATION  IT IS NO LONGER ACCEPTABLE TO  TREAT THE NOISE AS AN ISOTROPIC FIELD 3TRONG AZIMUTH 
 . Radar System Engineering  Chapter 9 – Synthetic Aperture Radar  78     Point C of the illuminated target area, or foot print, is seen during the “fly -by” so long, as the  carrier is within the half -power bandwidth of the directivity of the antenna.  This means that  information from the target point C can be collecte d over the entire time of the “fly -by”. 
 I, Slot Arrays, I RE Trans.,  vol. AP-8, pp. 286-297, May, 1960; pt. 
 AP-24, pp. 378-381, May, 1976.  102. 
 ATMOSPHERIC 26 POSITIONS OBTAINED BY ANY OF THE RANGE RADARS --3 OPERATIONS WERE CONCLUDED IN   AFTER THE METRIC ACCURACY OF MONOSTATIC RADARS WAS IMPROVED )N THE MID 
 TIME DESCRIPTION OF SPECTRUM AVAILABILITY  AS ILLUSTRATED IN &IGURES  AND  &)'52%   ! SNAPSHOT OF THE (& SPECTRUM AT NOON IN SUMMER AND AT A LOW SUNSPOT NUMBER  ZOOM 
 FACE TRAVELING WAVES THAT RADIATE POWER IN THE BACKWARD DIRECTION !N EXAMPLE IS THE OGIVE  A SPINDLE 
 WIDTH .,&- SINE 
 BAND INTERMODULATION DISTORTION AS DIFFERENT SIGNALS HAVE DIFFERENT EFFECTS ON THE RECEIVER #ROSS 
 12. Bamler, R.; Eineder, M. ScanSAR processing using standard high precision SAR algorithms. 
 Wang: Standar-dization of the Definition of the Radar Ambiguity Function,  lEEE Tratrs.. Vol. AES-10, pp. 
 SCALE WAVES OVER A RANGE OF WIND SPEEDS WELL BEYOND THOSE WHICH WOULD NORMALLY DISPERSE THE LIGHTER NATURAL OILS  SO THE EFFECT OF OIL SPILLS ON SEA CLUTTER SHOULD BE EXPECTED TO EXTEND TO THE HIGHER WIND SPEEDS )N FACT  AT THESE HIGHER WIND SPEEDS  THE DEPRESSION OF RADAR BACKSCATTER BY SUCH OILS AT 8 AND + A  BANDS CAN REACH  TO  D" AT INTERMEDIATE GRAZING ANGLES BETWEEN  AND   £x°{Ê / 
 The difference in the differ - ential reflectivity signatures is easily explained. Large raindrops assume flatter shapes  (approximated by oblate spheroids) as they fall and thus scatter back the horizon - tally polarized electric field more strongly than the vertically polarized electric field.  Hailstones, having an irregular shape, physically tumble while they fall and, therefore,  exhibit no preferred orientation on average. 
 5.2 SEQUENTIAL LOBING  The antenna pattern commonly employed with tracking radars is the symmetrical pencil beatt1  in which the elevation and azimuth beamwidths are approximately equal. However, a simple  pencil-beam antenna is not suitable for tracking rad_ars unless means are provided for deter­ mining the magnitude and direction of the target's angular position with respect to some  rderence direction, usually the a,cis of the antenna. The difference between the target position  and the reference direction is the angular error. 
 Polarization.  A complete description of the radar scattering cross section of  a target includes a description of its polarization scattering characteristics (not the  same as molecular polarization). The polarizing properties of targets are described  by the Stokes parameters, and the polarization coordinates can be represented on  the Poincare Sphere. 
 The parameter N is a scaled in- dex of refraction termed r efr activity. Since the barometric pressure p and the water vapor content e decrease rap- idly with height, the index of refraction normally decreases with increasing alti- tude. In a standard atmosphere, the index decreases at a rate of about 4.5 x 10~8 per meter of altitude. 
 This is more likely to  occur with short-range t;\r.gets since they generally require a higller data rate than long-range  targets.  In order to maintain maximum effectiveness ofthe radar and its computer when overloiicl-  ing occurs, some sort of priority system is required. Tasks which are not as time critical should  be deferred so that high-priority tasks can be accomplished. 
 Amulticavity oscillator has several possi- blemodes ofoscillation, inonly one ofwhich itoperates efficiently and smoothly. Great effort hasbeen devoted tounderstanding theconditions favorable tostable oscillations inagiven mode. We now know that stability depends onboth pulser and magnetron. 
 Irrrc~t~t~c~~iorrt~l ('orr/c~r.c~trc~c~ RAD.4R-77. pp. 423 426. 
 Hosseinmostafa, and S. P. Gogineni, “C-band backscatter measurements  of winter sea-ice in the Weddell Sea, Antarctica,” International  Journal of Remote Sensing ,   vol. 
 ON 
 There has been, however, no direct link made between  biological effects attributed to nontherm.al microwave origin and an adverse effect in humans.  The assumption of hazardous nontherma·l effects at low densities of radiation is a fear that has  not been substantiated.69 The demonstration of a biological effect due to microwaves does not  of necessity demonstrate a peril. Confusion also can result at times between microwaves and  other more harmful radiations. 
 13.23.—One-way switched-diode clamps. (a) Switched single diodes; (b)double. diodeclamps; (c)diodeswitched bycathode follower. 
 (ORIZON 2ADAR IN THE (& "AND v  0ROC )%%%  VOL    PP n  *UNE    $ ! "OUTACOFF  h"ACKSCATTER RADAR EXTENDS EARLY WARNING TIMES v  $EFENSE %LECTRONICS  VOL    PP n  -AY    'UEST EDITORIAL AND INVITED PAPERS IN SPECIAL ISSUE ON HIGH 
 Enhanced imagery using spectral-estimation-based techniques. Linc. Lab. 
 Tlie minimum detectable signal for  quarituni-lirnitcd detcctiorl isR5  where 11, = required nuniber of signal photoelectrons, q = quantum efficiency of the detector,  and r = observation time. Witli tliese substitutions, and with 2B = l/r (assuming a video  receiver) the radar equation can be written  OTHER RADAR TOPICS565 (Fig.14.15).(Thcattcnuation inrain.however. isstilllarge.)Thuslaserradarsoperating inthe infrarcdandvisihlcregionsachicvc-thc advalltagcs ofhighangularresolution, widebandwidth, . 
 These figures portray  the power output ( Po), power-added efficiency (PAE), and gain ( Gn). Performance for  each is referenced to 10 GHz for CW operation. The GaAs PHEMT operates at 7 V;  the GaN HEMT operates at 28 V . 
 CHANNEL MONOPULSE RECEIVER  COMBINES THE SUM AND DIFFERENCE SIGNALS  AT 2&  AS SHOWN IN &IGURE  4HE MICROWAVE RESOLVER IS A MECHANICALLY ROTATED 2& COUPLING LOOP IN CYLINDRICAL WAVEGUIDE 4HE AZIMUTH AND ELEVATION DIFFERENCE SIGNALS ARE EXCITED IN THIS GUIDE WITH  % 
 The amount of loss depends on the magnitude of the interference and is accounted for  in the signal-processing loss term.31 Ovals of Cassini.  The free space, maximum detection contour of a bistatic  radar’s benchmark range is a circle of radius RM, just as in the monostatic case. Such  a circle assumes constant radar cross-section and pattern propagation factors, which  are scenario- and geometry-dependent. 
 4(% 
 Figure 5shows the result of the proposed method where “ISR” represents the ISR data after polynomial ﬁtting. Note that we adopted the ISR data from all beams for polynomial ﬁtting, rather than the vertical beam only, because the TEC deviations between “Poker Flat ISR” and “Poker Flat ISR (average)” are small, and vertical data is too sparse to form a ﬁne polynomial ﬁtting. In Figure 5, “Ionosonde” stands for the original data obtained from DIDB, and “Improved” is our result with the topside proﬁle calculated from the known TEC To p. 
 Usually, operational requirements place a restriction on the  maximum scan time (time for the beam to return to the same point in space-) so that the radar  cannot dwell too long at any one radar resolution cell. This is especially true if there is a large  number of resolution cells to be searched. The number of resolution cells can be matcrial.ly  reduced if the narrow angular resolution cell of a pencil-beam radar is replaced by a beam in  which one dimension is broad while the other dimension is narrow, that is, a fan-shaped  pattern. 
 30, 1976.  16. Villard, 0. 
 H.: Low-Noise Microwave Sources, International Conference on Radar-Present ad  Future, Oct. 23-25, 1973, IEE (London) Publ. no. 
 C., and J. Gibbs: Ionospheric Analysis and Ionospheric Modeling, AFCRL Tech. Rept. 
 IEEE J. Sel. T op. 
 ING A COMPLEX MODULATED )& AS AN OUTPUT 4HESE SIGNALS ARE DIGITALLY SUMMED  CON 
 These features are susceptible to potential short-term failure due to  corrosion, metal migration, and dendritic growth if there are voltages on the circuitry  when exposed to an atmosphere that causes moisture to condense on the circuitry.  Thus, a hermetic package with a dry, nitrogen-filled interior is usually employed to  ensure long-term reliability. Hermetic packaging also brings with it the undesirable  effect of trapping inside the housing any molecular content that outgases into the  interior cavity. 
 C. J.: Minimizing the EfTects of Phase Quantization Errors in an Electronically Scanned  Array. " Proceedings of Symposium on Electronically Scanned Array Techniques and Applications,"  Rorrrcl Air Der~eloprne~~t Cerrrer Trclrnicc~l Doc~~rrttenrarj~ Report No. 
 ORDER NONLINEARITIES THAT WERE OMITTED FROM THE ABOVE EQUATIONS 4HE NEGATIVE THIRD HARMONIC IS THE DOMINANT COMPONENT PRODUCED BY NONLINEARITY 3IGNAL &REQUENCY !MPLITUDE OF 3PECTRAL #OMPONENT 
 Low power consumption isimportant. Many aircraft types have relatively low electrical-generating capacity, and itismost desirable tobeable toinstall aradar meant primarily asanavigational aidwithout thenecessity ofrevising the electrical installation ofthe aircraft. The setmust beable tooperate either from afixed-frequency 400-cps motor- alternator set, orfrom avariable-frequency engine-driven alternator, which may supply power atafrequency ashigh as2400 cps. 
 1.6 RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 1 Tracking radar . This is a radar that provides the track, or trajectory, of a target.  Tracking radars can be further delineated as STT, ADT, TWS, and phased array  trackers as described below: Single Target Tracker (STT ). 
 Equation (23.13) shows that the received power is directly proportional to the pulse width T. The noise power N is conventionally given by N = KTB (23.26) where K = Boltzmann's constant, 1.38 x 10~23 W/(HZ • K) T = receiver noise temperature, K B = receiver noise bandwidth For a matched receiver B « - (23.27)T The signal-to-noise ratio is therefore given by the proportionality Pr T T2 Tr a -^ ~ "^ <23'28)N K.TB *T Thus, for distributed targets and with the pulse volume filled with scatterers, the signal-to-noise ratio for a single pulse is proportional to the pulse width squared. This assumes that the peak power is unchanged and that the average power in- creases linearly with T. 
 +1, 
 BASED 3!2 STANDARDS &OR EXAMPLE  THE DIGITAL DATA RATE FOR THE %23 
 The AN/SPY-3 Multi-Function Radar (MFR) is the U.S. Navy’s first ship - board active phased array multifunction radar. It is an X-band active phased array  radar designed to meet all horizon search and fire control requirements for the Navy. 
 OFF WAS SLOWER THAN PREDICTED BY THE GAUSSIAN MODEL 4HIS LED TO NEW MODELS BASED ON POLYNOMIAL REPRESENTATIONS OF THE SPECTRUM USING AN EQUATION OF THE FORM   3FNN "F "N 0/,9 SIN \\ ¤ ¦¥³ µ´   ¤ ¦¥³ µ´P P      4HE  SPECTRUM SHAPE IS DETERMINED BY THE INTEGER  N  WHICH MUST BE  OR LARGER IN  ORDER FOR THE TWO FIRST SPECTRAL MOMENTS TO EXIST ! TYPICAL VALUE USED FOR THIS SPECTRUM  IS N    WHICH RESULTS IN  3F"F "0/,9  \\   ¤ ¦¥³ µ´   P     4HE RELATIONSHIP BETWEEN THE STANDARD DEVIATION OF THIS SPECTRUM AND ITS  
 The LO drive power specification defines how  much LO power is required by the mixer to meet its specified performance levels.  Typically, the higher the LO power, the higher the 1 dB compression point and third  order intercept point. Radar receivers often require high LO drive level mixers in  order to meet the challenging dynamic-range requirements. 
   
 However, for practical analysis, the load of the vehicles can be ignored, due to its minor magnitude relative to the gravity of the highway layer. The gravity of the highway layer can be obtained through the investigation of the highway structure and soil mass sample testing in the upper part of the soft soil layer. Erepresents the elastic modulus of the material, which is also called the deformation modulus; whereas ηdeﬁnes viscosity, also known as the viscosity coeﬃcient. 
 FIG. 7.4 Radiation pattern of two isotropic radiators. cations of the adjacent grating lobes at angles O1 and O2 are separated by TT(S/\) (sin G1 - sin B2) = IT. 
 NATION BETWEEN DESIRED ECHO SIGNALS AND UNDESIRED INTERFERENCE 4HE INTERFERENCE COM 
 With the residual data, we can solve the residual observation model with L1regularization. The accurate supports of subaperture images are estimated from the L1regularization image. Finally, the LS estimate on the accurate supports is calculated. 
 ch21.indd   23 12/17/07   2:51:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Penetrating Radar. 
 Inomata, “Observations of artificial slicks by X and Ka band airborne scat - terometers,” in Proc. Int. Geoscience and Remote Sensing Symp. 
 (It should be cautioned that the few meas~lrements available were  taken at low grazing angle and over a limited range of wind speeds.)  As with trees and grass, the value of a0 for snow increases with frequency and grazing  angle.77-78,102 Crusted snow (that which has melted and refrozen), produces higher valt~es of  o0 at 35 GHz and 94 GHz than wet snow, grass, or trees.  At microwaves the backscatter from rain can be explained according to the Rayleigh  scattering model with the reflectivity varying as the fourth power of the frequency (Sec. 13.7). 
 The early trials in the UK concentrated on a single 9 GHz demonstration system  fitted to a naval vessel. It was based around a 40 kW magnetron capable of 250 ns  pulses at a PRF of 1,000 Hz. It was interesting that the speed of rotation could be var - ied between 20 and 100 rpm. 
 There are two reasons forthis: (1)the only practical rectifiers atmicrowave frequencies are crystal detectors and these would burn outifconnected, asinFig. 5.1, toeven alow-power transmitter; (2)iftherectifier didsurvive, itwould respond toamplitude modulation ofthetransmitter and, since itcan befound from Eq. (2.4u). 
 This nadir return is always relatively strong, particularly  if there are specular backscattering components. Since any realistic antenna pattern  has a non-zero sidelobe directed toward nadir, the resulting reflection could appear in  the image. The main strategy is to avoid the ambiguity by choosing the PRF so that the  nadir return arrives at the same time that the radar is transmitting. 
 19, 1951.  22. George, S. 
 Precipitation. andTerrain. Proc.lEE,vol.110.pp.2139·-214X. 
  3YSTEM .OISE ,EVEL D"M(Z 
  0-  
 Spellmire, R. J.: Tables of Taylor Aperture Distributions, Hughes Aircraft Co., Syst. Dev. 
 Shrader V. Gregers-Hansen Equipment Division Raytheon Company 15.1 INTRODUCTIONTOMTIRADAR The purpose of moving-target indication (MTI) radar is to reject signals from fixed or slow-moving unwanted targets, such as buildings, hills, trees, sea, and rain, and retain for detection or display signals from moving targets such as air- craft. Figure 15.1 shows a pair of photographs of a PPI (plan position indicator) which illustrate the effectiveness of a properly working MTI system. 
 ARRAY ANTENNA MADE OF AN INFINITE CURRENT  SHEET v )%%% 4RANS  VOL !0 
 Ó°xÓ  2!$!2 (!.$"//+  Ó°£äÊ   1// 
 S. Raven, and P. Waterman: "Airborne Radar," D. 
 28,1945.. SEC. 10.11] MISCELLANEOUS COMPONENTS 389 practice many annoying points must beconsidered, including tempera- ture shift, change inback-bombardment heating ofthe magnetron cathode, change inpulser starting delay, and change inrectifier voltage. 
 9Ê-,Ê 
 WAVE STRUCTURE  4HIS IS USUALLY A SMOOTH WAVEGUIDE OR A LARGE RESONATOR .O ATTEMPT IS MADE TO REDUCE THE PROPAGATION VELOCITY OF THE ELECTROMAGNETIC WAVE WITHIN THIS STRUCTURE 4HE ELECTRON BEAM IS NOT CLOSE TO THE 2& STRUCTURE SO IT IS NOT AS LIMITED IN SIZE AS ARE THE STRUCTURES OF     )N ELECTRICAL ENGINEERING  2& STANDS FOR RADIO FREQUENCY  BUT IN RADAR  IT IS OFTEN USED TO MEAN THE RADAR FREQUENCY. £ä°{  2!$!2 (!.$"//+  SLOW 
 Any use is subject to the Terms of Use as given at the website. Sea Clutter.  SEA CLUTTER  15.256x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 beyond the conventional optical horizon, such perturbations could produce strong  focus-defocus variations along the surface illumination profile74,75 or a general rise  in the local grazing angle.47 Figure 15.18 gives an experimental example of the effect  of ducting  on very low-angle sea clutter. 51 The grazing angle given as the abscissa  is actually a plot of inverse range, so the lifting of the cross section by ducting over  an order-of-magnitude span of ranges is very likely due to a rise in the local grazing  angle produced by refraction in the evaporative layer (first 10 meters or so above  the surface).47 Such effects should be suspected whenever the radar propagation path  extends beyond the optical  horizon. 
 (13.8) and (13.9).21'23 In later presentations of this data,24 the median values of a° were replaced by means, raising them by about 1.6 dB, and the area A in Eq. (13.7) was redefined in terms of a more realistic tapered footprint, adding another 1 to 2 dB. This means that there is a difference of 3 to 4 dB between the earlier and later presentations of the same data, and since these results are widely used and quoted, it is important to ensure that the proper definition of <r° is being used when comparing them with clutter data that has been taken by other experimenters or in using these results in clutter predic- tions. 
 M.: Laser Radars, chap. 37 of" Radar Handbook." M. 1. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Tracking Radar.  TRACKING RADAR  9.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 9 of pulses. 
 Electron ., vol. 12, pp. 75.78–81.83,  January 1980. 
   %23  %.6)3!4  AND 'EOSAT %2-'&/  ARE NORMALLY PLACED INTO EXACT 
 ENCE WAVEFORM $&4 &OR EXTENDED RANGE COVERAGE  REPEATED PROCESSING OPERATIONS ARE REQUIRED WITH RANGE DELAYS OF - SAMPLES BETWEEN ADJACENT OPERATIONS USING THE OVER 
   #OSINE SQUARE (ANNING   
 J. Blinchikoff, “Quadriphase code-a radar pulse compression signal  with unique characteristics,” IEEE Trans. Aerospace and Electronic Systems , vol. 
 Figure 9. The block diagram of the ReBP–based SAR–SS. 192. 
 BEAM KLYSTRONS   OR -"+ )T HAS BEEN SAID  THAT THE  NUMBER OF BEAMLETS IN AN -"+ MIGHT BE FROM  TO . £ä°n  2!$!2 (!.$"//+  4HE CHIEF MOTIVATION FOR THE MULTIPLE 
 Osbrink: GaAs FET Amplifiers are Closing Fast on the Low-Noise  Narrowband Leaders, Microwaoe System News, vol. 5, pp. 63-67, April/May, 1976. 
 ÓÈ°£ä  2!$!2 (!.$"//+  SHIPS WERE  NAUTICAL MILES 37 OF +ISKA DURING THE FIRING 4H E RADAR CONTACTS WERE  ACTUALLY RETURNS FROM LAND THAT HAD BEEN DUCTED OVER THE HORIZON 3EVERAL METEOROLOGICAL CONDITIONS WILL LEAD TO THE CREATION OF DUCTS 7HERE THESE CON 
 Noise on the transmitted signal and on any conversion oscillators within the missile will be spread throughout the doppler spectrum by the feedthrough and clutter and mask the target signal if the noise is not adequately controlled. Noise reduction is thus one of the key technologies required for good radar seeker performance. Clutter and Feedthrough Considerations.2'5'7 The presence of clutter and feedthrough is one of the primary limitations on the performance achievable in a seeker and has been one of the main design drivers in the evolution of radar guided missiles. 
 All of these countries carried out experiments with CW wave  interference, and even though the French and the Japanese deployed such radars opera-  tionally, they proved of limited value. Each country eventually progressed to pulse radar  operation and the advantages pertaining thereto. Although the advantages of the higher  frequencies were well recognized, except for the United States and Great Britain none of the  others deployed radar at frequencies higher than about 600 MHz during the war. 
 CESS WIDE BANDWIDTH LINEAR &- WAVEFORMS 4HE ADVANTAGE OF THIS TECHNIQUE IS THAT IT  ALLOWS THE EFFECTIVE )& SIGNAL BANDWIDTH TO BE SUBSTANTIALLY REDUCED  ALLOWING DIGITIZA 
 Millimeter wavelengths might also find application when the propa-  gation path does not traverse a large part of the earth's atmosphere, as when a ground-based  radar directs its energy at or near the zenith. (At 94 GHz the two-way loss In transiting  the entire atmosphere is about 1.7 dB at zenith, 3.5 dB at 60" from the zenith, and 10 dB at 80"  from the zenith.)82  Submillimeter wavelengths.83s84 The advantages of high resolution, wide bandwidth, and  small antenna aperture are even more prevalent in the submillimeter proportion of the electro-  magnetic spectrum than at millimeters. The attenuation in the clear atmosphere, however, is  far worse than at millimeters and varies from about 10 dB/km at l-mm wavelength to more  than 100 dB/km at 0.1-mm wavelength. 
 WJ.:Faster. Lighler3-1)Radars inSightforTactical Warfare. Electronics. 
 International Co11fere11ce RADAR-77, pp. 559-563, 25-28 Oct., 1977. JEE  (London) Conference Publication no. 
 The individual deflections due tothe two pairs ofplates add vectorially. The deflection sensitivity atthe screen depends upon the geometry ofthe deflecting plates themselves, their distance from the screen, and the velocity ofthe electrons asthey pass the plates. The two pairs aresimilar ingeometry, but, since they are atdifferent distances from the screen, their deflection sensitivities are unequal. 
 A simple radar target such as a smooth sphere sot cause degradation of the angular-  tracking accuracy. The radar cross section of a sphere is independent of the aspect at which it  is viewed; consequently, its echo will not fluctuate with time. The same is true, in general, ofa  radar beacon if its antenna pattern is omnidirectional. 
 Any measurement of velocity, whether by the rate of change of range or by the doppler frequency shift, requires time. The longer the time of observation, the more accurate can be the measurement of velocity. (A longer observation time also can increase the signal-to-noise ratio, another factor that results in in- creased accuracy.) Although the doppler frequency shift is used in some applica- tions to measure radial velocity (as, for example, in such diverse applications as the police speed meter and satellite surveillance radars), it is more widely em- ployed as the basis for sorting moving targets from unwanted stationary clutter echoes, as in MTI, AMTI (airborne MTI), pulse doppler, and CW radars. 
 LENGTHS PROVIDE EVEN MORE INFORMATION RELATED TO THE EVENTUAL INTERPRETATION OF THE SIZE DISTRIBUTIONS  WATER 
 MARY OF ITS MANY MODES&)'52%    2!$!23!4 
 Geogr. Sin. 2017 ,37, 1917–1924. 
 It cannot be made broadband without a  decrease in efficiency. The slow-wave circuits of traveling-wave tubes have a broader hand-  width than klystron resonant cavities; and when used for the output of a klystron, as in thc  Twystron, a broad bandwidth can be achieved with the peak and average power capabilities of  a klystron.  The C-band Varian VA-146 Twystron family of tubes provides peak power outputs from i 200 kW to 9 MW with bandwidths greater than 10 percent. 
 Hollis, R.: False Alarm Time in Pulse Radar, Proc. IRE, vol. 42, p. 
 More often, however, asingle wave isgenerated and thesecond obtained from itbyaphase-inverting amplifier. More sophisticated sawtooth generators arenecessary when precision isrequired. Allofthese endeavor toprotide great linearity inone ofthe .,J1;GF—FIG.13.30.—Sawtooth generators using triode clamps. 
 Air Traffic Control Radar  Beacon System (ATCRBS) array is mounted on top. ( Courtesy Northrop Grumman  Corporation ) ch12.indd   21 12/17/07   2:31:26 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Dybdal and C. O. Yowell, “VHF to EHF performance of a 90-foot quasi-tapered anechoic  chamber,” IEEE Trans ., vol. 
 CIENCY WHEN USING SHAPED PULSE WAVEFORMS  AS THERE IS WITH OTHER MICROWAVE TUBES 4HIS IS AN IMPORTANT REASON FOR ITS USE FOR 5(& 
 This might be due  to the amplifier being better able to produce the desired radar waveforms. 10.6 TRANSMITTER SPECTRUM CONTROL The increasing demand for electromagnetic spectrum for both civilian and military  applications has accentuated the need to control the spectrum of radar transmitters  to avoid interference with users of the electromagnetic spectrum operating at other  frequencies. The aspects of concern here are those that affect RF tube selection and  achievement of minimum spectrum occupancy by the transmitters discussed previously  in this chapter. 
 There- fore ineach adjacent pair thedipoles areexcited inphase opposition; but because ofthereversal ofoneofthem they radiate inphase, producing a broadside beam. Ifalternate di- poles were absent the beam would still beformed, but would beac- companied byother strong beams comparable toundesired orders ofdif- fraction from anoptical diffraction grating. Asitis,theside lobes are from 2to5percent asintense asthemain besm.. 
 THE 
 CHARGE  IS MOVED TO THE RIGHT SIDE OF THE EQUATIONS  LEAVING ONLY THE KNOWN INCIDENT FIELD ON THE LEFT SIDE 7HEN THE PROCESS IS REPEATED FOR EACH PATCH ON THE SURFACE  A SYS 
 2, and consequently the surface-related cross section inferred from the received signal strength in any given measurement will depend upon the path length. Moreover, the role of sea spray in both scattering and absorption will certainly be more important than at the lower microwave frequencies. It is difficult to find clutter data at frequencies above Ka band, although H- and V-polarized returns at 95 GHz at a grazing angle of 1° were reported, both with values of close to -40 dB.46'47 Interestingly, this is just the cross sectionCROSSWlND UPWIND/DOWNWIND 'HUNTER/SENIORSITTROPRELATIVEdB . 
 Lfore recent advances inantenna development have introduced antenna types, other than the parabolic cylinder fedbyalinear array, which give thebeam characteristics required forlong-range surveillance and control. The method that now appears most promising uses a section ofaparaboloid ofrevolution forthe reflector. The periphery ofthis surface iscuttogive anaperture several times greater inwidth than inheight, and thereflector isfedbyseveral horns ordipoles arranged along avertical line passing through thefocus. 
 DIMENSIONAL  CORNERS ALSO REFLECT MOST STRONGLY IN THE SAME SENSE AS THE INCIDENT CIRCULAR POLARIZATION .ATURALLY OCCURRING DIHEDRALS  SUCH AS ROUGH ROCK FOR 
 Main-Beam Clutter. The main-beam clutter-to-noise power can be approximated from Eq. (17.2) by substituting the intersected area for dA and summing over all intersections within the main beam.30 C^ /Vi2Ba2(CT^) ^G7 GK a° N (4Tr)3 Lc K T8 Bn R3 cos a The summation limits are the lower and upper edges of the smaller of the transmit and receive beams and where 6az = azimuth one-half power beamwidth, rad T = compressed pulsewidth a = grazing angle at clutter patch The remaining terms are as defined following Eq. 
 FICIENT INDEPENDENT OF THESE PARAMETERS 5SE OF A DIFFERENTIAL SCATTERING CROSS SECTION IMPLIES THAT THE RETURN FROM THE GROUND  IS CONTRIBUTED BY A LARGE NUMBER OF SCATTERING ELEMENTS WHOSE PHASES ARE INDEPENDENT 4HIS IS PRIMARILY BECAUSE OF DIFFERENCES IN DISTANCE THAT  ALTHOUGH SMALL FRACTIONS OF TOTAL DISTANCE  ARE MANY WAVELENGTHS 3UPERPOSITION OF POWER IS POSSIBLE FOR THE COM 
 pulser, allthe requirements for pulse shape, accuracy ofpulse spacing, and flexibility ofpulse rates must be met. The important parts oftheregenerative pulser circuit shown inFig. 10.33 arethepulse-forming network attheleftand thethree-winding pulse transformer which provides thenecessary plate-grid feedback tomake the circuit self-driving. 
 QUENCY ARE MULTIPLIED UP 4HESE VARIATIONS ARE PRODUCED DURING SIGNAL FILTERING AND MAY BE PRESENT ON THE INPUT SIGNAL &OR CHIRP WAVEFORMS  THIS CAN RESULT IN A SIGNIFICANT DEGRADATION IN THE RANGE SIDELOBE PERFORMANCE !LSO  PRACTICAL MULTIPLIERS MAY HAVE A SIGNIFICANT PHASE VARIATION AS A FUNCTION OF FREQUENCY )F THE  INPUT SIGNAL PHASE DISTOR 
 SEC. 3.7] USEOFABSORBENT MA1’ERIALS 69 approach. Atarget consisting oftwoplanes intersecting atright angles gives specular reflection foralldirections ofobservation perpendicular to theline ofintersection. 
 Tobesure, wehave sodras- tically oversimplified the problems that nosignificance can beclaimed for theexact shape ofthecurve. Never- theless, themain features ofthecurve- especially theexistence oftheplateau regions Iand 111, whose vertical sepa-FIG. 2.8.—l3ffect ofscanning speed onstorage gain, assuming 6“ beam- width, and 4-see storage time, with PRF =500PPS. 
 FREQUENCY OSCILLATORS IS USED TO DESCRIBE NOISE  THUS  THE  STATISTICS OF THE FADING SIGNAL AND THE STATISTICS OF RANDOM NOISE ARE THE SAME 4HIS MEANS THAT THE ENVELOPE OF THE RECEIVED SIGNAL IS A RANDOM VARIABLE WITH ITS  AMPLITUDE DESCRIBED BY A 2AYLEIGH DISTRIBUTION 3UCH DISTRIBUTIONS HAVE BEEN MEA 
     &)'52%   ( 
 For clarity, the relationship between altitude and TEC is plotted in Figure 3c, so we can get a direct idea about the altitude where the mid-value /angbracketleftBcosθ/angbracketrightlies. Bcosθstill monotonically decreases in Figure 3c, but the curve changes from convex to concave at the peak height. 206. 
 WAVE AND DIGITAL COMPO 
 THE RECEIVER BYW. H.JORDAN 12.3. Special Problems inRadar Receivers.—Radar receivers, though similar inprinciple toall radio receivers, differ from them insome respects. 
 J. Ryan and C. Kirby, “Iceberg detection performance analysis,” Report TP 14391E, Transportation  Development Centre, Transport Canada, 2005. 
 ( c) Constant-apparent-velocity contours (“isodops”) are confocal hyperbolas with the axis  parallel to the platform velocity vector. ( d) Set of intersecting concentric circles and confocal hyperbolas.  (Courtesy of SciTech Publishing, Inc .) Z Sensor Nadir (a) (b) (c) (d)Nadir lineX Nadir lineXNadir lineXYY Y YX ch17.indd   11 12/17/07   6:48:49 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 DETECTOR OUTPUTS 4HE RANGE 
 VIOUS NEAR 
 338–343, July 1977. 27. H. 
 Skolnik. M. 1.: Survey of Phased Array Accomplishments and Requirements for Navy Ships,  " I'hased Array Antennas," A. 
 A particular radiation pattern may be more readily obtained  with the array than with other microwave antennas since the amplitude and phase of each  array element may be individually controlled. Thus, radiation patterns with extremely  low sidelobes or with a shaped main beam may be achieved. Separate monopulse sum and  difTerence patterns, each with its own optimum shape, are also possible. 
 LOSS  FAST 
 611 15.13 General Design ofthe AN/APS-10. 614 15.14 Detailed Design ofthe AN/AP&10 616 CHAP. 16. 
 / 
 The cross section is oscillatory with frequency within  this region. The maximum value is 5.6 dB greater than the optical value, while the value of the  first null is 5.5 dB below the optical value. (The theoretical values of the maxima and minima  may vary according to the method of calculation employed.) The behavior of the radar cross  sections of other simple reflecting objects as a function of frequency is similar to that of the  sphere.' 5-25  Since the sphere is a sphere no matter from what aspect it is viewed, its cross section will  not be aspect-sensitive. 
 Laser radars operate at even higher frequencies.  The place of radar frequencies in the electromagnetic spectrum is shown in Fig. 1.4. 
 LINE CLUTTER "ECAUSE OF SPECULAR REFLEC 
 3!2 o MODE IS  M OVER A  KM BY  KM IMAGE FRAME 4HESE    INNOVATIVE 3"2S ARE RELATIVELY SMALL  AT LEAST BY %ARTH 
 NIQUE  WHERE  . IS THE NUMBER OF SIMULTANEOUS RECEIVE BEAMS )N EITHER CASE  I T IS NECES 
 VI was reported in [2] and the assessment of a prototype ASV Mk. VII was given in [ 3]. Radar trials are notoriously dif ﬁcult to undertake and even without equipment unreliability are prone to uncertainty in the weather sea conditions and targets. 
 As will be shown, the improvement that re- sults from this type of integration is usually not as great as with ideal predetection integration of the same number of pulses. Nevertheless, postdetection integration produces worthwhile improvement. Moreover, "ideal" predetection integration is virtually unachievable because the echo fluctuation from most moving targets severely reduces the degree of phase coherence of successive received pulses. 
 Of course, we  will not create the line 7 impulses in hardware but will instead realize the impulse areas  digitally as numbers in registers. A block diagram showing how this process might be implemented in hardware is  shown in Figure 25.9. The IF signal is sent to two mixers. 
 The transmitted signal expressed in complex form is u(t)e'2"f01, where u(t) is the . 412 INTRODUCTION TO RADAR SYSTEMS  complex-modulation function whose magnitude I u(t) I is the envelope of the real signal, and/0  is the carrier frequency. The received echo signal is assumed to be the same as the transmitted  signal except for the time delay T0 and a doppler frequency shift fd. 
 Itsconstruction isshown inFig. 12,19. The input circu;t isaT-network consisting ofthree self-induct- ances. 
 62 HOW RADAR WORKS  a quarter of a second. The degree of brilliance is impor-  tant, for with modern tubes we can focus the electron  beam right down to a small circle about 7 mm. in dia-  meter, so that there is not a very large area to cause  fluorescence on any one part of the tube. 
 In spite of limitations, the lower frequencies  arc attractive wlien low cost and lotig range are triore important than otlier factors.  14.4 HEIGHT-FINDER AND 3D RADARS  111 many applications a k~iowledgc of target Iieigl~t might not be needed. An obvious examplc  is where the target is know11 to lie on the surface of the earth, and its location is given by the  range and a7imuth coordinates. 
 However, the simpler receiver is not as sensitive because of increased noise at the lower  intermediate frequencies caused by flicker effect. Flicker-effect noise occurs in semiconductor  devices such as diode qetectors'and cathodes of vacuum tubes. The noise power produced by  the flicker effect varies as ·t!f«, where tx, is approximately unity. 
 High  performance transistors at higher frequencies than S band are usually built using  compound semicondctors. Such transistors can result in high cutoff frequencies and  demonstrate gain at frequencies much higher than silicon. For example, electrons in  gallium arsenide (GaAs) travel approximately twice as fast as they do in silicon. 
      
  
 VELOCITY CONTOURS hISODOPSv  ARE CONFOCAL HYPERBOLAS WITH THE AXIS  PARALLEL TO THE PLATFORM VELOCITY VECTOR  D  3ET OF INTERSECTING CONCENTRIC CIRCLES AND CONFOCAL HYPERBOLAS  #OURTESY OF 3CI4ECH 0UBLISHING  )NC    
 7.4. It is generated by moving the parabolic contour over an arc of a circle  whose center is on the axis of the parabola. It is useful where a scan angle less than 120° is  required and where it is not convenient to scan the reflector itself. 
  D" REGION WITH AVERAGE SIDELOBES OF  TO  D" BELOW ISOTROPIC 3,# HAS  THE POTENTIAL OF REDUCING NOISE JAMMING THROUGH THE ANTENNA SIDELOBES  AND IT IS USED FOR THIS PURPOSE IN OPERATIONAL RADARS  !S EXPLAINED IN 3ECTION   %##- TECHNIQUES AGAINST CHAFF ARE MAINLY THOSE  BASED ON COHERENT DOPPLER PROCESSING  )N PARTICULAR  THE REFERENCE DESCRIBES A  COMPARISON OF FIXED AND ADAPTIVE DOPPLER CANCELERS APPLIED TO CHAFF DATA RECORDED BY A MULTIFUNCTIONAL PHASED 
 885. 54. D. 
 Measurements can be obtained with scale models on a  pattern range. 29 An example of such model measurements is given by the dashed curves in  Fig. 2.17. 
 Spatial resolu - tion and swath span 3 m to 20 m, and 20 km to 55 km, respectively, mode-dependent.  †  Slip-SAR is a modified ScanSAR mode, in which the antenna pattern is dragged along the surface at a slower rate  than in the conventional strip-map mode. The result is larger doppler bandwidth, hence enhanced azimuth resolu - tion, and also a wider imaged area than a pure SpotSAR can support. 
 Englund, C. R., A. B. 
 20.) The single-channel monopulse provides in effect an instantaneous AGC. Per- formance in the presence of thermal noise is about equal to that of the three- channel monopulse. However, the limiting process generates a significant cross- coupling problem,21 causing a portion of the azimuth-error signal to appear in the elevation-angle-error-detector output and elevation error to appear in the azimuth-angle-error-detector output. 
 as a result of using both feeds for  transmission. The phase center on transmit is half-way between the two feeds, and the phase  center on receive alternates from one feed to the other.) As the antenna pointing-direction  changes from the port to starboard side of the vehicle, the sign of the difference signal must be  reversed to keep the displaced beams in the proper orientation.  The dashed curves of Fig. 
 POINTING DIRECTION  THE INTEGRAL MULTIPLES OF  4YS  MAY BE USED TO STEER THE COLUMNS &IGURE  . £Î°Óä  2!$!2 (!.$"//+  £Î°{Ê * 
 180 THEGATHERING ANDPRESENTATION OFRADAR DATA [%C.69 were large gaps initsvertical coverage (Figs. 6.14 and 615). The range onlow-flying aircraft was poor. 
 Contents     ix   Spurious Responses of Mixers  ...........................  3.8  Characteristics of Amplifiers and Mixers  .............  3.11  3.5 Local Oscillators  ..................................................... 
 185. S. Kato T. 
 III). However, at that time few trials were actually undertaken on ASV Mk. VI, due to the limited availability of aircraft. 
 pp. 197-201. December, 1957. 
 Itisalsopossible toturntheCFAonandoffwiththeRFdrive-pulse, without theneedfor apositive pulseapplied tothecutoffelectrode attheendofthedrivepulse.Thecutoff electrode callbedesigned tooperate withanappropriate constant positive-bias thatallows sufficient reentrance oftheelectrons whentheRFdriveisonbutbeunabletomaintain the electron streamwiththeRFdriveoff.l?ThisiscalledRFkeying,orself-keying. Inprinciple, it isthesimplest waytomodulate theCFA. Although RFkeyingandd-coperation aresimplerpulse-modulating methods thancath­ odepulsing, theyhavenotbeenaswidelyusedinthepastashasthecathode pulser.Usually therehavebeenfactorsotherthanmodulator sizethatdetermine themethodofmodulation bestusedinpractice.15 Unliketubesthatemploythermonic cathode emission fortheirsupplyofelectrons, atube withacoldsecondary-electron cathode doesnotexperience adroop,ordecay,ofthepulse amplitude withtime.Inaddition totheinsensitivity ofelectron emission withpulseduration, thereisalsoaninsensitivity todutycycleifthecathode iscooledsufficiently sothatthe secondary emission properties ofthecathodedonotchangewithtemperature.17Thushighand lowduty-cycles canbeemployed interchangeably ifthecathode temperature ismaintained cool enough, usuallybelowabout400or500°C. 
 Such coordinates must be established for each particular case. Figure 12.8 shows the geometry for horizontal travel. The coordinate a is along the isodop, and TI is normal to it. 
 SIGHT VELOCITIES OF DIFFERENT PARTS OF THE SCENE (OWEVER  THE CROSSRANGE RESOLUTION MAY ALSO BE CONSIDERED TO RESULT FROM THE  LARGE SYNTHETIC APERTURE  MUCH AS FINE CROSSRANGE RESOLUTION WO ULD ALSO RESULT FROM A LARGE  REAL APERTURE 0ER %Q   THE CROSSRANGE RESOLUTION PEAK 
 Radar System Engineering  Chapter 14 – Bibliography  170     − Hovanessian, S. A.; Radar systems design and analysis; Artech House; 1984; UB - Ka [85A3012]  − Schleher, D. C.;  MTI Radar; Artech House; 1978 ; UB -Ka [80E26]  − Currie, N. 
 LENT METRIC UNITS 4HE TECHNICAL VISION OF THE  MEETING WAS REMARKABLE &OR INSTANCE  IT WAS SEEN  THAT IN THE FUTURE IT WOULD BE POSSIBLE TO OVERLAY RADAR DATA A UTOMATICALLY ONTO A CHART  IMAGE DISPLAYED ON A hTELEVISIONv TYPE SCREEN 4HIS WAS NOT TO  BE REALIZED ON COM 
 EARITY WILL RESULT IN THE GENERATION OF UNDESIRED SIDEBANDS THAT WILL APPEAR AS RESIDUE AT THE CANCELER OUTPUT ! DISCUSSION OF !$ CONVERSION CONSIDERATIONS WAS PRESENTED IN 3ECTION  )N THE ADAPTIVE -4) IMPLEMENTATION DESCRIBED ABOVE  THE NUMBER  OF ZEROS ALLO 
 They  perform all the RF functions, including RF power generation, phase shifting to steer  the antenna beam in elevation, and receive preamplification to provide a low-noise  figure. The RF power is generated by direct amplification through modular solid- state power amplifiers in the row transmitters. The energy from these power modules  is combined within the row transmitter, which drives the row feed. 
 MEDIUM 02&   
 BASED RADARS  . 
 X I,, Svv Lvv  Percentile 20 50 80 20 50 80 20 50 80 20 50 80 1 Figure 2.20 Same as Fig. 2.19. but for circu-  ,I 1140 I lar polnri~ation. 
 CLUTTER SPECTRUM MODELS ARE COMPARED IN &IGURE  !S NOTED IN "ILLINGSLEY ALL THREE  MODELS ARE IN REASONABLE AGREEMENT FOR THE UPPER n D" OF THEIR RANGE BUT DIFFER  APPRECIABLY AT THE LOWER VALUES OF CLUTTER SPECTRAL DENSITY %STIMATED VALUES OF THE SPECTRAL SPREAD OF LAND CLUTTER FROM FORESTED REGIONS AND  FOR DIFFERENT WIND SPEEDS ARE SHOWN IN 4ABLE  4HE VALUES IN THE TABLE ARE BASED ON "ILLINGSLEYS PARAMETER  A   BUT COLUMNS HAVE BEEN ADDED WITH THE CORRESPONDING  RMS SPECTRAL SPREAD IN MS !N EXAMPLE OF A MEASURED LAND CLUTTER SPECTRUM IS SHOWN IN &IGURE  4HE SPECTRAL SHAPE PARAMETER  A CAN BE ESTIMATED AS THE SLOPE OF THE  UPPER  SKIRT OF THE SPECTRUM IN D" PER MS DIVIDED BY LN  4HESE VALUES OF  A  WERE ADDED IN THIS FIGURE &)'52%   #OMPARISON OF GAUSSIAN  EXPONENTIAL  AND POLYNOMIAL SPECTRA FOR AN RMS  SPECTRAL SPREAD OF RV    MS. Ó°£{  2!$!2 (!.$"//+  4HE VALUES OF RMS SPECTRAL SPREAD OF LAND CLUTTER AS DERIVED FROM THE DATA IN  "ILLINGSLEY AGREE QUITE WELL WITH PREVIOUS STUDIES )T CAN PROBABLY SAFELY BE STATED  THAT THE POLYNOMIAL MODEL OF LAND CLUTTER SPECTRA IS FAR TOO PESSIMISTIC AT SPECTRAL  VALUES BELOW n D" AND SHOULD BE AVOIDED FOR RADAR ANALYSIS REQUIRING A LARGE CLUTTER ATTENUATION VALUE 4HE CASE FOR THE EXPONENTIAL MODEL  AS PRESENTED BY "ILLINGSLEY   IS QUITE CONVINC 
 Even though the computational complexity was not an issue during the course of this work, the speckle ﬁltering, optical ﬂow processing and merging are computationally expensive processes. On a dual core computer (Intel Core i7 6500U, Santa Clara, CA, USA) with 16 GB of memory, it takes slightly less than 3.5 min to process one region. There are many factors that are contributing to this time. 
 CONVERSION IS ADVANTAGEOUS  BECAUSE PERFORMANCE IS NOT LIMITED BY AMPLITUDE AND PHASE IMBALANCES THAT EXIST IN ANALOG PRODUCT 
 This method isused inthe2500-va Type PU-7 inverter designed byWincharger and built byWincharger and Airways. Itisshown schematically inFig 14.18. Asthe input voltage orinverter load changes, the resistance ofthe carbon pile inthe voltage regulator varies tomaintain constant output voltage. 
 40 INTRODUCTION TO RADAR SYSTEMS  Figure 2.16 Experimental cross section of the B-26 two-engine bomber at IO-cm wavelength as a function  of azimuth angle. (From Ridenour,'' courtesy McGraw-Hill Book Company, Inc.)  account of aspect changes and shadowing of one component by another) is computed and ttlc  component cross sections are combined to yield the composite value. The " theoretical " values  of Fig. 
 The sea surface wind ﬁeld reanalysis data was obtained from the Europe Centre for Medium-Range Weather Forecasts (ECMWF) on 11 June 2010. The grid resolution of the wind ﬁeld is 0.125◦×0.125◦over the ocean surface. In addition, the corresponding current ﬁeld reanalysis data was obtained from GODAS with a spatial resolution of (1/3)◦×1◦. 
 M. Sl~crman: Pulse Radar for Trajectory Instrumcnt.ntion, paper prcscritcd nt  Sixtli National Fliglit Test instrumentation Symposium, Instrument Society of America, San Diego,  Calif.. May 3, 1960. 
 DEPENDENT TWO 
 TARGET INDICATION -4)  OR DOPPLER RADAR  THE RATIO OF  THE CLUTTER 
 Schelkunoff, “A mathematical theory of linear arrays,” Bell, Syst. Tech. J ., vol. 
 For optimum combinations todate, satisfactory transmission can beobtained over arange of0°to70°. Beyond this value thetransmission decreases very rapidly, reaching zero transmission at90°incidence. Having determined areasonable shape fortheradome, itisthen neces- sary tocheck theangles ofincidence bymeans ofanantenna raydiagram. 
 Moskowitz, L. I.: The Wave Spectrum and Windspeed as Descriptors of the Ocean Surface, Nrlval  Research Laboratory Report 7626, Washington, D.C., Oct. 30, 1973. 
 Diamond, “Small Arrays—Their analysis and their use for the design of array elements,” in  Phased Array Antennas , A. A. Oliner and G. 
 MENTS v )%%% 4RANS  VOL !0 
 Theslow-wave structure canalsoprovide alimittoTWTcapability. It seemsthatthoseslow-wave structures bestsuitedforbroadbandwidth (likethehelix)have poorpowercapability andpoorheatdissipation. Asacrifice inbandwidth mustbemadeif high-power isrequired ofaTWT.Ifthebandwidth istoosmall,however, thereislittle advantage tobegainedwithatraveling-wave tubeascompared withmulticavity klystrons. 
 296-302, October, 1964.  71. Siebert, W. 
 ELEMENT DISTANCE   FOR THE ARRAY OF RECEIVING ELEMENTS ARE RESPECTIVELY  AND  4HE BLANKING IS SEPARATELY APPLIED ON THE RECEIVED DATA AT THE TWO CARRIER FREQUENCIES SUBSEQUENTLY  THE SEPARATE BLANKING BITS ARE PROCESSED  BY A LOGIC /2 THE GLOBAL BLANKING LOGIC   4HE ENSUING &IGURE  DISPLAYS THE BLANKING CURVES FOR THE TWO SEPARATE CARRIER FREQUENCIES AND FOR THE LOGIC /2 )T IS NOTED THAT THE FREQUENCY DIVERSITY AND THE LOGIC /2 PROVIDE AN IMPROVEMENT OF THE BLANKING PROBABILITY THIS IS DUE TO THE DIFFERENT SHAPES OF THE ANTENNA PATTERNS AT THE TWO SLIGHTLY DIFFERENT CARRIER FREQUEN 
 OLD IS COMPUTED FOR EACH RESOLUTION CELL AS A LINEAR COMBINATION OF ORDER STATISTICS EXTRACTED FROM RANKED SAMPLE VALUES OVER A WINDOW SPANNING NEIGHBORING RANGE BINS  ANTENNA BEAMS  AND DOPPLER CELLS  WITH PROVISIONS FOR ADAPTING THE WINDOW SHAPE NEAR STRONG VARIATIONS IN NOISE OR CLUTTER POWER /FTEN THE RESULTS ARE SIMILAR TO THOSE PREDICTED BY THE LOG 
 This constrains achievable data transfer rates, regardless of channel  bandwidth. An associated problem is vulnerability to intercept and jamming inherent in  widebeam apertures. An X or Ku band MFAR can emit power levels in the multi-kilo - watt range with main-beam beamwidths of a few degrees, affording high data rates and  significant resistance to jamming and intercept. 
 Because oftheshortcomings ofthe early radar equipment, and the “blind spots” inthe coverage ofindi- vidual sets! itwas felt tobeessential tocombine the information from allradar stations atacentral point. This was done ataso-called “filter center. ” Inalarge underground bombproof room was mounted acentral table whose surface was agridded map ofEngland. 
 , -ARGOT  AND . * 3 3TACY  h.O EVIDENCE  FOR THICK DEPOSITS OF ICE AT THE LUNAR SOUTH POLE v .ATURE  VOL   PP n    - 4 :UBER AND ) 'ARRICK 
 A full explanation of the Split system and of its  operational use in conjunction with known polar dia-  grams of aerials is necessarily wordy and complex. But  if we are content to take the polar diagrams themselves  as really a rather rough sketch of the area covered by the  lines of shoot of the aerial the operational aspect is not  too difficult; and the Split display on the CRT is, of  course, quite simply achieved by arranging that one trace  is produced with a slightly different value of voltage on  the X plates, to shift the alternate display slightly to  one side.  You can regard the Type A display as a very elemen-  tary, one-directional map of what is happening. 
 POLARIZEDv PAIR  BY DEFINITION  CANNOT BE MUTUALLY COHERENT SINCE IT CORRESPONDS TO INTERLEAVED SAMPLES OF THE BACK 
 The effect onthedesign ofi-famplifiers will bedeveloped inthis section. The lack oflow-noise r-famplifiers orconverters inthe microwave region has meant that most microwave receivers convert the r-fsignal toani-fsignal directly inacrystal mixer and then amplify thei-fsignal. This lack ofprevious amplification complicates the design ofthe i-f amplifier, asisshown bythe following expression, given inChap. 
 Observations along the Paciﬁc coast of the UnitedStates indicate frequent ducting, but no clear indication of its seasonal trendis available. Meteorological conditions in the Yellow Sea and Sea of Japan,including the island of Honshu, are approximately like those of thenortheastern coast of the United States. Therefore, ducting in this areashould be common in the summer. 
 It is almost always used as a nieans to  achieve good range resolution with a long pulse. Furthermore, the jammer usually must be  forced to spread its power over a much wider hand than the spectral wicitli of most pirlse-  compression radars in order to significantly reduce its effectiveness. Thus pirlse conipression  should not be given too large a credit as a major ECCM technique, although it is certainly a  positive factor. 
 In other words, microwave transistors are much more cost-effective when  the required radar system average power can be provided by a lower peak power at a  higher duty cycle. As a result, there have been relatively few direct replacements of  older low duty cycle transmitters by solid-state transmitters. Some initiatives, such as  the solid-state AN/SPS-40 replacement that was motivated by the attractive reliability,  maintainability, and availability characteristics of a modular solid-state system, have  not seen the success once envisioned due to the acquisition cost of solid-state replace - ment transmitters. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers. 
 On receiving, the noise figure is established by the FIGURE 13.32  Parallel-feed networks ch13.indd   49 12/17/07   2:41:01 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 
 Angle (deg) Noise (dBW)• = R4th Loss• = R4th + L 0 = Frequency* = El. Angle ^ 1 deg.» = Noise• = R4th Loss. = R4th + L 0 = Frequency* = El. 
 TINUOUS AT THE PHASE 
 POINT FEED AND LOW 
 BAND RADIO WAVES  0ART ) v '%#  %LECTRONICS  ,TD  3TANMORE  %NGLAND  -EMORANDUM 3,-  *ULY    ! 2 $OMVILLE  h4HE BISTATIC REFLECTION FROM LAND AND SEA OF 8 
 LSeeSec.113.. SEC. 913] THEAN/APQ-7 (EAGLE) SCANNER 293 ifthe waveguide carries the energy from right toleft, the scan extends for300totheright ofthecenter line oftheaircraft. 
 135. Sensors 2019 ,19, 2921 Figure 3. Theθ–ΔRrelationship curve. 
 4.34  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 times the PRF velocity  (first blind speed) to each measured ambiguous radial velocity  as follows:  Vf F NJ KR unfoldcentroid FFT0 = +−  λ 2[ ]… …  (4.10) where fRl/2 is the first blind speed (PRF velocity), Fcentroid  is the amplitude-cen - troided doppler filter number, NFFT is the number of filters in the doppler filter bank,  and [ −J … 0 … K] represents the set of doppler ambiguity numbers covering the  maximum negative and positive doppler-velocities for the targets of interest. For  cases where there are only a few ambiguities in doppler, doppler correlation may be  performed prior to or in conjunction with range correlation to minimize ghosting. High-PRF Ranging. 
 ﬁgure 4.1. The azimuth beamwidth was 10 °. To accommodate the higher transmitter power a waveguide feed replaced the coaxial feeder used on ASV Mk. 
 7.1 if the phase distribution  across the aperture is not constant. Following the first sidelobe are a series of minor lobes  which decrease in intensity with increasing angular distance from the main lobe. In the vicinity  of broadside (in this example 100 to 115"), spillover radiation from the feed causes the sidelobe  level to rise. 
 Protection against Extraneous Radiations. Antijamming.— Although the sensitivity ofaradar repeiver isnormally limited bythe noise produced inthereceiver, extraneous radiation may beoccasionally picked uponthe radar antenna. Such radiation may, forexample, be theresult oftheoperation ofother microwave equipment inthevicinity. 
 lO)  applies to a one-dimensional line source lying along the z axis. For the two-dimensional  aperture of Fig. 7.2, A(z) is the integral of A(x, z) over the variable x.]  Equation (7.10) represents the summation, or integration, of the ind ivi<lual contributions  from the current distribution across the aperture according to Huygens' principle. 
 In both measurement and analysis, the radar receiver and transmitter are usually taken to be in the far field of the target (discussed in Sec. 11.4), and at that dis- tance the scattered field Ex decays inversely with the distance R. Thus, the R2 term in the numerator of Eq. 
 TO 
 4. L. V . 
 Fire control F. Fixed ground W. Armament   (peculiar to armament  not otherwise covered)N. 
 RADAR FEEDS MAY HAVE ANY OF  A VARIETY OF CONFIGURATIONS  3INGLE APERTURES ARE ALSO EMPLOYED BY USE OF HIGHER 
 Radar images produced by real or synthetic aperture radars can be used for scattering coefficient measurement. Unfortunately, most such systems are uncalibrated; so the results are somewhat dubious, even on a relative basis when images are produced on different days. Relative calibration has been introduced into some systems.12'18'20-73"75 Absolute calibration, which also serves as relative calibration in some cases, can be achieved by using strong reference targets, with the ARC repeaters especially suitable.76 Another approach that has been used is to measure scattering from reference areas with a ground-based or helicopter system that is well calibrated and to compare the images to these measured values.73'77 Bistatic Measurements. 
 A  proper blanking logic allows this signal to pass. Targets and/or jammers J situated in  the sidelobes give small main but large auxiliary signals so that these targets are sup - pressed by the blanking logic. It is assumed that the gain GA of the auxiliary antenna  is higher than the maximum gain Gsl of the sidelobes of the radar antenna. 
 Any use is subject to the Terms of Use as given at the website. Radar Cross Section.  RADAR CROSS SECTION  14.356x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 from the angle domain to the cross-range domain must be performed offline in  this example. The fast Fourier transform (FFT) is invariably exploited to expedite   the processing. 
 The speed control Vx is bipolar and must be capable of reversing the sign of the ∆(q )  signal in each channel when the antenna pointing angle changes from the port to the  starboard side of the aircraft. FIGURE 3.12  MTI improvement factor for DPCA compensation as a  function of the fraction of the horizontal phase center separation W that  the horizontal antenna aperture is displaced per interpulse period, VxTp/W.  W = 0.172 a, where a is the horizontal aperture length. 
 1975. (Also availahlc in ref. I.)  20. 
 The measured  difference in the resonant frequencies of the two cavities is due to the different dielectric  properties (or index of refraction) of the gases within the two cavities. This frequency difference  can be calibrated in terms of the index of refraction of the atmosphere in the sampling cavity.  Although the airborne refractometer may give excellent data on the variation of the index of  refraction, it is not always suitable for many applications since it requires an aircraft or  helicopter. 
 87. Delaney, W. P.: An RF Multiple Beam-Forming Technique. 
 Figure 16.3 shows the loci of constant radial velocity along the sur- face. In order to normalize the figure, a flat earth is assumed, and the normalized radial velocity Vn = VJVg is presented as a function of azimuth angle ty and nor- malized ground range RlH, where H is the aircraft's altitude. Instead of a single clutter doppler frequency corresponding to a constant ra- dial velocity (VB in Fig. 
 This is thought of as an ECCM technique, but it is really  no more than good antenna design. The cross-polarized jamming in this case attacks  a design deficiency in the radar. The requirement for good cross-polarization design  practice in a radar antenna system extends to any auxiliary ECCM antennas as well. 
 IEEE , vol. 62,  no. 6 pp. 
 Each beam position overlaps by as much as 90% and multiple frequency  FIGURE 5.26  Terrain height estimation8 (Courtesy SciTech Publishing ) ch05.indd   29 12/17/07   1:27:09 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 
 TION IS COMMONLY USED SIGNAL 
 no. 105, pp. 8--13, 1973. 
 Radar Conf. Publ . 281, 1987, pp. 
 19 in Radar in Meteorology , Atlas (ed.), Boston: AMS, 1990, pp. 153–189. 15. 
 Cartledge, W. H. Drury, E. 
 R.: New Techniques for MTI Clutter-1,ocking. Radur ---Prt*st*nt tind Frrt~~re, i1:t' (I.ontlor~)  Conf. Publ. 
 When extrapolating toother wavelengths, itshould beborne inmind that the wavelength dependence ofEq. (6)cannot beexpected tohold rigorously. Classes ofmoving reflectors that arenegligible at10cmmay become ofimportance at3cm. 
 NAL MAY BE INCOHERENT WITH THE RADAR WAVEFORM AND OPERATE IN A hSPOTv OR hBARRAGEv FASHION TO RAISE THE NOISE FLOOR IN BOTH RANGE AND DOPPLER SEARCH SPACES TO POTENTIALLY IMPAIR DETECTION PERFORMANCE  OR IT CAN BE COHERENT WITH THE RADAR WAVEFORM  AS IN THE CASE OF DECEPTION JAMMING  WHICH MAY GENERATE FALSE TARGETS AND POTENTIALLY IMPAIR THE TRACKING SYSTEM FROM FOLLOWING THE TRUE TARGET )MPACT OF )ONOSPHERE  !N IMPORTANT ASPECT THAT DISTINGUISHES /4( RADAR FROM  LINE 
 Ó°ÓÓ  2!$!2 (!.$"//+  STRADDLING LOSS AND WOULD REPRESENT A SINGLE FIGURE 
 If 8/ A [in Eq. ( 11.38)] is identified with tin Eq. ( 11.39), and if xis identified wit hf, the theoretical  rms error can be obtained by analogy to the time-delay accuracy as given by Eq. 
 With the antenna rotating at 15 revolutions perminute, a radar set having a PRR of 800 pulses per second will produceapproximately 9 pulses for each degree of antenna rotation. ThePERSISTENCE of the radarscope, i.e., a measure of the time it retainsimages of echoes, and the rotational speed of the antenna, therefore,determine the lowest PRR that can be used. Pulse Length Pulselengthisdeﬁnedasthedurationofthetransmittedradarpulseandis usually measured in microseconds. 
 The production supervisor was Gayle Angelson.  Library of Congress Cataloging in Pubilcation Data  Skolnik, Merrill Ivan, date  Introduction to radar systems.  Includes bibliographical references and index. 
 This results in the lower of the two  peaks of the symmetrical L\/E ratio being placed in the direction of the bisector of the target  and image. Under this condition, the values of L\/E in the direction of the target and its image  are equal. The estimate of target elt!vaUQt\ is unaffected by the phase and amplitude of the  image. 
 The holes correspond,  roughly, to the inductance L, and the slots correspond to the capacity C. In ttie desired mode  of operation (the so-called n mode) the individual C's and L's are in parallel, and the frequency  of the magnetron is approximately that of an individual resonator. The cathode (4) is a fat  cylinder of oxide-coated material. 
 The interest in development is being  fueled by both the military for high performance sensors and also by commercial  interests for high-power wireless base-station amplifiers. In particular, the GaN HFET  device demonstrates physical properties that make it useful as a high gain device with  very high power output capability into the W band. The SiC MESFET will likely be  competitive at the lower frequency ranges of L band through C band.23 The thermal conductivity of the SiC substrate is superior to GaAs by nearly an  order of magnitude, and the normalized power outputs are much, much higher in the  wide bandgap semiconductors than currently being achieved using GaAs at any volt - age. 
 If a signal  occupies a time T and a bandwidth B, a change in time aT allows a change in bandwidth B/a.  Thus if a signal is stretched in time, say by a factor. a = 10, the bandwidth can be reduced by a  factor of 10, and the signal can be processed with more practical narrow band circuitry. 
 Radar Handbook." M. I. Skolnik (ed.). 
 Unive rsity  of Munich, IEEE Aerospace El. Systems Magazine,  pp. 13- 18, Dec. 
 POWER STAGE IS COMPRISED OF TEN CHANNELED 474!S    EIGHT OF WHICH ARE REQUIRED IN COMBINATION   LEAVING TWO AS REDUNDANT BACKUP 4HE RADAR MASS IS  KG INCLUDING THE REFLECTOR AND FEEDS  SATELLITE DRY MASS INCLUDING THE RADAR IS  ^ KG  WHICH AT THE TIME SET THE  STANDARD AS THE SMALLEST 3!2 SATELLITE IN %ARTH ORBIT 4HE POWER SUBSYSTEM DELIVERS UP TO  K7 DURING IMAGING OPERATIONS 4HE SPACECRAFT ORBIT IS  n INCLINATION   ^ KM ALTITUDE   
 AP-10, pp. 351-352, May, 1962.  141. 
 RURAL AREAS IS NOT UNCOM 
 PHASE COMPONENTS OF MISMATCH REFLECTIONS FROM THE APERTURE AND OF OTHER UNBALANCED REFLECTIONS ARE ABSORBED IN THE TERMINATIONS 4HE IN 
 It certainly does not apply  when the energy is radiated in the endfire direction.  Equation 8.13 applies for a uniform aperture illumination. With a cosine-on-a-pedestal  aperture illumination of the form A, = a. 
 To realize adequate signal- to-noise performance, it is customary to perform the first amplification in a CW radar at an intermediate frequency such as 30 MHz. To obtain the necessary coherent local oscillator signal, various types of sidestep techniques are employed. These include modulators, balanced modulators, single-sideband generators (SSG), or phase-locked oscillators. 
 TIME SIGNALS AND SYSTEMS v PRESENTED AT &IRST  )%%% 7ORKSHOP ON 3IGNAL 0ROCESSING %DUCATION 30%    (UNT  48  /CTOBER    7 - 7ATERS AND " 2 *ARRETT  h"ANDPASS SIGNAL SAMPLING AND COHERENT DETECTION v  )%%% 4RANS  /N !EROSPACE %LECTRONIC 3YSTEMS  VOL !%3 
 (The  factor of! appears here for the same reason it was included in Eq. (14.3).) When a" directive"  element-pattern is used the spacing necessary between elements to avoid grating Jobes can he  much greater than J../2. In the SAR, the directive pattern of the real antenna can be considered  as the element pattern of the synthetic array. 
 A simplistic view of how these three beams perform motion compensation is illus - trated in Figure 3.26 for the case where the aperture is parallel with the radar’s platform  velocity vector. The first pulse return’s phase center is advanced by aperture weight - ing, the second pulse return’s phase center is essentially unchanged from the quiescent  weights, and the third pulse return’s phase center is retarded by aperture weighting.  Given ideal antenna patterns, and an aperture large enough to adjust the phase centers  T2Transmit Module (1) Transmit Module (m) D1 DmDigital Receiv er (1) Digital Receiv er (m)… T1 Digital BeamformerT2T1 Adaptiv e Weight Generator …Waveform Generator Doppler Filter BankAutomatic Detector T1, T2; PRI dela ys FIGURE 3. 
 Combining these high-resolution  cloud measurements with high sensitivity is one of the technical goals for acquiring  new information regarding cloud effect on the Earth’s climate. Clear-Air Wind Profiling Radars.  Another form of doppler radar that has  become widely used, especially in the research community, is the so-called wind pro - filing radar,10 or “wind profiler.” Wind profilers usually take the form of VHF and  UHF multiple fixed-beam systems, pointing vertically and at angles approximately  15° from the zenith to infer profiles of the horizontal wind averaged over the area of  measurement. 
 ENCE ! n BEAM WILL PROVIDE A CROSS 
 Moore: A High Performance CW Receiver Using Feedthru Nulling, Micro­ wave J., vol. 6, pp. 63-71,'September; 1963. 
 Younis, and W. Wiesbeck, “Implementation of Digital Beam forming  for  Synthetic Aperture Radar”,  Proceedings International ITG/IEEE Workshop on Smart Ante nnas, CD- ROM, Duisburg, Germany, April 2005   15.4 Antennas general   − Antenna Theory, Analysis and Design; Constantine A. Balanis; John Wiley & Sons Publication; ISBN 0 -471-66782- X  − Antenna Engineering Handbook; Richard C. 
 M..T.Tamama. andN.Yamauchi: AJapanese 3-dRadarforAirTrafficConlro/' Electronics. vol.44,pp.68-72,June21.1971.. 
 45. Martindale, J. P. 
 GROWTH &OR EXAMPLE  IN OUR  
 V . Oppenheim and R. W. 
  AND ELEVATION 
 Based on the unique mapping between such offsets and the Doppler parameters, the DPEC can be accurately implemented. By showing that the EMAM outperforms the existing DPEC methods in both the computer simulations and the real airborne data processing experiments, the effectiveness of the presented approach has been validated. Both the computer simulations and the real airborne data processing experiments show that based on the EMAM method, the targets both at the azimuth center and edges are well focused, indicating that the EMAM method can accurately estimate and compensate the spatial variance of the Doppler rate and the derivative of the Doppler rate. 
 118  12.1.7 Quality of the CFAR Threshold and CFAR Loss ................................................. 118  12.1.8 Conclusions ........................................................................................................... 123  12.2 Design of Low Side Lobe Chirp Pulse Compression ................................................... 
 MOVING TRANSFORMATION JUST DESCRIBED YIELDS A SIMPLE INTER 
 Zrnic, “Resolution enhancement  technique using range oversampling,” J. Atmos. Ocean. 
 BASED  .,&-  AND ,&- WAVEFORMS &)'52%     -ATCHED FILTER OUTPUT OF 3 BAND   
 578 INDEX  Parallel-plate feed, 309  Parametric amplifier, 35 1  Passive TR-limiter, 363, 364  Pattern synthesis, 254-258  Penetration color tube, 357  Performance chart, magnetron, 195- 197  Performance figure, radar, 63  Permanent magnet focusing, 202  Phase-coded pulse compression, 428-431  Phase-comparison monopulse, 165-167  Phase detector, in MTI, 105  Phase-frequency array, 303, 334  Phase-in-space 3D radar, 543  Phase-phase array, 335  Phase-sensitive detector, 156, 160  Phase shifter quantization, 321-322  Phase shifters, 286-298  Phased array antennas, 278-337  Phasers, 287  Pi mode, magnetron, 193  PIN diode, 290  Pincushion radar, 316  Pipology, 387  Plumbing loss, 57-58  Polarization:  antenna, 227  circular, 504-506  for target classification, 436  Polarization agility, and glint reduction, 172  Polarization-twist Cassegrain, 242-243  Polyphase codes, 432 . I  Postamplification beam forming, 3 10-3 11  Postdetection integration, 29-32  Power gain, antenna, 225-226  Protector TR, 364  Power programming, in 3D radar, 302  PPI, 6, 355  Precipitation:  attenuation by, 503  scattering from, 498-503  Predetection integration, 29  Prelook receiver, 548  Probability density function, 20-23  Probability distribution function, 23, 26  Probability of detection, 27-29  cumulative, 64  for Swerling mudels, 48  Probability of false alarm, 24  Propagation of radar waves, 62, 441-461  Propeller modulation, 76  Proximity (VT) fuze, 71  Pseudorandom code, 429  Pulling figure, magnetron, 199  Pulse chasing, in bistatic radar, 559 Pulse compression, 420 434  and frequency scan, 303  Pulse compression ratio, 422  Pulse doppler radar, 139- 140  Pulse-forming network (PFN), 2 14  Pulse repet it ion frequency, 2  staggered, 1 14- 1 17  Pulser, 214  Pushing figure, magnetron, 196  Quadrature channel, in MTI, 119  Quadrature component, in monopulse, 176  Quantization:  in MTI, 120 )  in phase shifters, 321-322  Quantization error, FM-CW altimeter, 87  Quantization lobes, 32 1-322  and triangular spacings, 334  Rabbit-ear oscillations :  in CFA, 2 11  in TWT, 207, 208  RADAM, 437  Radar applications, 12- 13  Radar block diagram, 5-7  Radar cross section, 33-46  aircraft, 39-44  bird, 509  bistatic, 557-559  cone-sphere, 35  definition, 4, 33  example values, 44  fluctuation models, 46-52  insect, 510  man, 44  reduction of, 553  ,rod, 34-35  ships, 142-143  sphere, 34  and target classification, 435  Radar definition, 1-2  Radar frequencies, 7-8  Radar equation, 17-65  bistatic, 556-557  derivation of, 3-4  laser, 565-566  OTH, 530-531, 535  SAR, 521-522  surface clutter, 471-474  surveillance, 64  for weather radar, 499-500  Radar history, 8-12  Radar operator, 386-387  578INDEX Parallel-plate feed,309 Parametric amplifier, 351 PassiveTR-Iimiter, 363,364 Patternsynthesis, 254-258 Penetration colortube,357 Performance chart,magnetron, 195-197 Performance figure,radar,63 Permanent magnetfocusing, 202 Phase-coded pulsecompression, 428-431 Phase-comparison monopulse, 165-167 Phasedetector, inMTI,105 Phase-frequency array,303,334 Phase-in-space 3Dradar,543 Phase-phase array,335 Phase-sensitive detector, 156,160 Phaseshifterquantization, 321-322 Phaseshifters,286-298 Phasedarrayantennas, 278-337 Phasers, 287 Pimode,magnetron, 193 PINdiode,290 Pincushion radar,316 Pipology, 387 Plumbing loss,57-58 Polarization: antenna, 227 circular, 504-506 fortargetclassification, 436 Polarization agility,andglintreduction, 172 Polarization-twist Cassegrain, 242-243 Polyphase codes,432 Postamplification beamforming, 310-311 Postdetection integration, 29-32 Powergain,antenna, 225-226 Protector TR,364 Powerprogramming, in3Dradar,302 PPI,6,355 Precipitation: attenuation by,503 scattering from,498-503 Predetection integration, 29 Prelookreceiver, 548 Probability densityfunction, 20-23 Probability distribution function, 23,26 Probability ofdetection, 27-29 cumulative, 64 forSwerling models,48 Probability offalsealarm,24 Propagation ofradarwaves,62,441-461. Propeller modulation, 76 Proximity (VT)fuze,71 Pseudorandom code,429 Pullingfigure,magnetron, 199 Pulsechasing, inbistaticradar,559Pulsecompression, 420434 andfrequency scan,303 Pulsecompression ratio,422 Pulsedoppler radar,139-140 Pulse-forming network (PFN~214 Pulserepetition frequency, 2 staggered, 114-117 Pulser,214 Pushing figure,magnetron, 196 Quadrature channel, inMTI,119 Quadrature component, inmonopulse, 176 Quantization: inMTI,120 ..,> inphaseshifters,321-322 Quantization error,FM-CW altimeter, 87 Quantization lobes,321-322 andtriangular spacings, 334 Rabbit-ear oscillations: inCFA,211 inTWT,207,208 RADAM,437 Radarapplications, 12-13 Radarblockdiagram, 5-7 Radarcrosssection,33-46 aircraft,39-44 bird,509 bistatic,557-559 cone-sphere, 35 definition, 4,33 example values,44 fluctuation models,46-52 insect,510 man,44 reduction of,553 ,rod,34-35 ships,142-143 sphere,34 andtargetclassification, 435 Radardefinition, 1-2 Radarfrequencies, 7-8 Radarequation, 17-65 bistatic,556-557 derivation of,3-4 laser,565-566 OTH,530-531, 535 SAR,521-522 surfaceclutter,471-474 surveillance, 64 forweatherradar,499-500 Radarhistory,8-12 Radaroperator, 386-387. 
 (3)must compete forrecognition. The level offluctuations inanotherwise quiescent electrical circuit can bedescribed inmany equivalent ways. One description ofwhich weshall make useisthefollowing. 
 A large  bandwidth system (e.g., pulse compression radar) can acquire independent samples in  range in a short dwell time that can be averaged, thus reducing the dwell time for each  beam and reducing the total volume coverage scan time. Fast mechanical scanning   (> 60 deg/sec) produces deleterious spectrum broadening effects157 that electronic step  scanning easily avoids since the beam is fixed in space during the dwell time. A favored  approach is to utilize a one-dimensional phased array that is electronically scanned in  elevation while slowly rotating in azimuth.158 In this way, a full hemispheric volume  can be covered in 1–2 minutes and smaller sector volumes may be covered in less than  1 minute.159 Several military radars and aviation radars utilize electronically scanned  beams but the expense of a fully capable system has prevented more than only a few  meteorological radar systems from being designed and built.160,161 Rapid-scanning  phased array radars have also been studied extensively in Europe.162 An alternative approach is to employ digital beamforming or frequency-steering   techniques to transmit and simultaneously receive multiple beams using parallel  receivers. 
 OUS WITH OTHER HEIGHT SIGNALS IF THE REPEAT PERIOD WERE AN INTEGRAL NUMBER OF DAYS &OR 40  THE TIME OF DAY FOR EACH SUBSEQUENT OBSERVATION SLIPS BY ABOUT TWO HOURS 4HE 40 REPEAT PASS FOOTPRINT LOCATION ACCURACY IS BETTER THAN  o KM  A REQUIREMENT THAT IS  BOUNDED BY THE CROSS 
 5,  pp. 585–598, September 1976. 105 R. 
 TRANSIENT 3UPPRESSION  7HEN   THE 02& IS CHANGED FOR MULTIPLE 
 LawEnforcement. Inaddition tothewideuseofradartomeasure thespeedofautomobile trafficbyhighway police,radarhasalsobeenemployed asameansforthedetection of intruders. Military. 
   AND !.!03 
 A DBS map may take a sec - ond to gather over an angle of 70 °. Depending on the angle from the aircraft velocity  vector, a SAR map of a few feet resolution may take tens of seconds to gather at X  band. DBS and SAR are compared in a qualitative way in Figure 5.32. 
 IEEE T rans. Aerosp. Electron. 
 14. pp. 9-10. 
 11.17c, is a geometry that provides better performance for large pulse-compression  ratios.22 Shallow grooves etched in the delay path result in SAW reflections to form a delay  that depends on the frequency. The structure is less sensitive to fabrication tolerances than  conven tionlll transducers.  A "typical" SAW dispersive delay line developed for linear FM pulse-compression radar  had a bandwidth of 500 Milz and all uncornpressed pulse width.of 0.46 The center  frequency was 1.3 GHz and the compressed pulse width was 3 ns. 
 (2.18); (3) decide on a desired value of Pd (in different circumstances, values ranging from below 0.5 up to as high as perhaps 0.99 may be selected); and (4) for this value of Pd and for the value of Vt found in step 2 find the required signal-to-noise ratio through Eq, (2.19). This requires evaluating the function p5n(v), taking into account the number of pulses integrated. Iteration is required, in this procedure, to find the value of D0 corresponding to a specified probability of detection and number of pulses integrated. 
 Resolution is5ft(1.5m)inazimuth and7ft(2.1m)inrange.(Col/rtesy El/l'iwlltnelltal Research Jnstillite ofMichigan.). Inlens~ty modified  verlicol sweep  I  Lens  Figure 14.5 Recordirig of SAR signal on photograpllic film with the aid of a CRT  on a tilted plane, the different phase-front curvatures are corrected and the image is erected by  insertion of a conical lens placed at the phase-history film located in plane PI. This erect image  has its focus at infinity. 
 Aspect Entropy Extraction at the Pixel Level Our method uses only one polarization, and thus we select one pass and its’ HH polarization from the Gotcha data. Figure 8is the coherent complex image of the full scene obtained by using the BP algorithm, and the pixel size is 0.025 m.     Figure 8. 
 R. Jensen, “Design and performance analysis of a phase-monopulse radar altimeter for  continental ice sheet monitoring,” in Proceedings , IEEE International Geoscience and Remote  Sensing Symposium IGARSS'95 , Florence, Italy, IEEE, 1995, pp. 865–867. 
 CATION IN THE CALCULATION OF THE ELEMENT IMPEDANCE VARIATIONS )N ADDITION  IMPEDANCE MEASUREMENTS MADE IN SIMULATORS CORRESPOND  TO THE ELEMENT IMPEDANCE IN AN INFINITE  ARRAY )N SPITE OF THE ASSUMPTIONS  THE INFINITE 
 arXiv arXiv:1604.02472, 2016. Available online: https://arxiv.org/pdf/1604.02472.pdf (accessed on 24 June 2019). [ CrossRef ] 12. 
 2.3 DEFINITION AND EVALUATION OF RANGE FACTORS There is an element of arbitrariness in the definition of most of the factors of the radar range equation, and for some of them more than one definition is in common use. Since the definitions in these cases are arbitrary, one definition is in principle as good as another. However, once a definition has been chosen for one factor, there is no longer freedom of choice for one or more of the others. 
 7 in Currie, N. C. (ed.): "Technology of Radar Reflectivity Measurement," Artech House, Norwood, Mass., 1984. 
 ING FROM EXPLORATION OF THE !RCTIC AND !NTARCTIC ICECAPS AND THE PERMAFROST REGIONS OF .ORTH !MERICA  TO MAPPING OF GRANITE  LIMESTONE  MARBLE  AND OTHER HARD ROCKS AS WELL AS GEOPHYSICAL STRATA 4HE RADAR DATA SHOWN IN &IGURE  WERE COLLECTED AT &INSTERWALDERBREEN GLACIER  3VALBARD  .ORWAY  WHICH IS AN ISLAND ALMOST  NORTH OF .ORWAY 4HE GLACIER IS AN  KM LONG  LAND 
 (From Trunk,ss co11r1esy Proc. IHEE.)  Nonideal equipment. The transmitter power introduced into the radar equation was assumed  to be the output power (either peak or average). 
 ALLY NON 
 ING DETERMINISTIC 2& NULLING A   AMPLITUDE AND PHASE  CONTROL AT EACH ELEMENT AND  B  PHASE 
 95-99, March, 1952.  9. Wilkins, A. 
 Amplifiers may be placed between the individual antenna elements and the beam­ forming (phase-shifting) networks to amplify the incoming signal and compensate for any  losses in the beam-forming networks. The output of each amplifier is subdivided into a number  of independent signals which are individually processed as if they ·were from separate receivers.  Postamplification beam forming. 
 butitsstudyalso servesasameansforbetterunderstanding thenatureanduseofthedoppler information contained intheechosignal,whether inaCWorapulseradar(MTI)application. Inaddition toallowing thereceived signaltobeseparated fromthetransmitted signal,theCWradar provides ameasurement ofrelativevelocity whichmaybeusedtodistinguish movingtargds fromstationary objectsorclutter. 3.2CWRADAR Consider thesimpleCWradarasillustrated bytheblockdiagram ofFig.3.2(1.Thetransmitkr generates acontinuous (unmodulated) oscillation offrequency fo,whichisradiated hythe antenna. 
 A more thermally stable device allows for the more efficient power com - bining of transistor cells within a package. This contributes to a lower performance  sensitivity to load mismatch—a problem that has complicated the design process for  the Si BJT. Figure 11.7 and Figure 11.8 summarize the performance envelope for com - mercially available silicon bipolar junction transistors and silicon LDMOS FETs for  given transmit waveforms.11–14 GaAs PHEMT. 
 REFLECTED BEAMWIDTH THUS  THE RECEIVED ENERGY IS REDUCED 4HE THIRD SOURCE IS TYPICALLY CAUSED BY SHADOWING  FOR EXAMPLE  BY AN AIRCRAFT FUSELAGE BLOCKING ONE OF THE BISTATIC PATHSTRANSMITTER OR RECEIVER ,/3 TO A SCATTERING CENTER )N GENERAL  THIS DIVERGENCE RESULTS IN A BISTATIC 2#3 LOWER THAN THE MONOSTATIC 2#3  FOR COMPLEX TARGETS &OR EXAMPLE  %WELL AND :EHNER  MEASURED THE MONOSTATIC AND  BISTATIC 2#3 OF COASTAL FREIGHTERS AT 8 BAND WHEN BOTH THE TRANSMITTER AND THE RECEIVER WERE NEAR GRAZING INCIDENCE 4HE DATA WAS PLOTTED AS A RATIO OF  BISTATIC TO MONOSTATIC  2#3  R "R- 4HE MEASUREMENTS GENERALLY MATCH +ELLS MODEL OF THE  DATA POINTS    SHOW BISTATIC 2#3 LOWER THAN MONOSTATIC 2#3 4HE REDUCTION IN BISTATIC 2#3 STARTS BETWEEN A   n AND A   n AND TRENDS DOWNWARD TO R "R-    
 ELLIPTICITY RATIO !N EARLY MODEL OF A 2AYTHEON REFLECTARRAY GAVE  AN ELLIPTICITY RATIO OF LESS THAN  D" WITH SCANS UP TO  n  CORRESPONDING TO A THEORETICAL  RAIN REJECTION OF AT LEAST  D" !T THE SAME TIME  AN AIRCRAFT TARGET WOULD TYPICALLY LOSE APPROXIMATELY  D"  LEAVING A RELATIVE NET IMPROVEMENT OF  D" OF RAIN REJECTION 0HASED !RRAYS WITH 6ERY 7IDE "ANDWIDTH  ! RADAR SYSTEM THAT HAS THE CAPABIL 
 While there are few two-dimensional (infinite cylindrical) objects in the phys- ical world, analyses of the scattering from two-dimensional structures are very useful. A two-dimensional object is, by definition, a cylinder formed by the pure translation of a plane curve to plus and minus infinity along an axis perpendicular to the plane of that curve. Many scattering problems become analytically tracta- ble when there is no field variation along the cylindrical axis, such as when the infinite structure is illuminated by a plane wave propagating at right angles to the cylinder axis. 
 Woodward, Probability and Information Theory with Application to Radar , Pergamon  Press, 1960. 70. D. 
 (4.8)  where lln is the nth blind speed. If ,1.. is measured in meters,.fP in Hz, and the relative velocity in  knots, the blind speeds are  (4.9)  The blind speeds are one of the limitations of pulse MTI radar which do not occur with  CW radar. 
 Here the device is called the boxcar generator.11 The box.car  generator was also mentioned in the discussion of the MTI receiver using range-gated  filters (Sec. 4.4). In essence, it clamps or stretches the video pulses of Fig. 
 AES-12, pp. 793-798, November, 1976.  83. 
 RANGE FUNCTIONAL REQUIREMENTS OF THE 4(!!$ MISSION 4HE 4(!!$ ELEMENT COMPONENTS WORK IN CONCERT TO DETECT  ASSIGN  AND DESTROY INCOMING SHORT 
 The axis of rotation was in the plane of the plate parallel to one edge; normal incidence to the incident wave is 0°, at the left side of each chart, with edge-on incidence at 90° near the right side. The specular return from the plate is the large peak at 0°, which is predicted with quite good accuracy by the flat-plate formula given in Sec. 11.3. 
 With IF limiting, these harmonics  are filtered out using bandpass filtering after limiting prior to A/D conversion, mini - mizing the degradation due to limiting. All radar systems contain some form of Transmit/Receive (T/R) device to protect  the receive electronics from the high-power transmit signal. In many systems, an RF  front-end limiter is also required in order to prevent the receiver from being damaged  by high input power levels from the antenna that may occur as a result of leakage from  the T/R device during transmit mode or from interference due to jammers or other  radar systems. 
 Similar results for a  two-dirne~isiorial riiodcl consisting of equal-cross-section scatterers uniformly spaced over a  circular area indicate that the probability that the apparent radar center lies outside this target  is 0.20.  Angle fluctuations in a tracking radar are reduced by increasing the time constant of the  AGC system (reducing the band widt h).29.33.34 Ho wever, this reduction in angle fluctuation is  acconipariied by a new cotnponent of noise caused by the amplitude fluctuations associated  witti tlie echo signal; that is, narrowing the AGC bandwidth generates additional noise in the  vicinity of zero frequency, and poorer tracking results. Amplitude noise modulates the  tracking-error sigrials and produces a new noise component, proportional to true tracking  errors. 
 The ARSR-3 antenna generates two beams slightly displaced in elevation for the purpose  of reducing the echoes from high-speed surface clutter, such as from automobiles and trucks.  These clutter echoes can be large enough and have a sufficiently high doppler frequency shift . 540 INTRODUCTION TO RADAR SYSTEMS  to not be completely eliminated by MTI doppler processors. 
 Geosci. and Remote Sensing Symp. [IGARSS-83] , San Francisco, IEEE/URSI, 1983,   pp. 
 Compensation for Surface Refractivity Variation. For extremely accurate height calculations at long ranges, it is possible to correct for variations in surface refractivity in otherwise normal atmospheric refraction conditions. Such a tech- nique is used, for example, in the General Electric series of solid-state 3D radars. 
 249 Berkay Kanberoglu and David Frakes Improving the Accuracy of Two-Color Multiview (2CMV) Advanced Geospatial Information(AGI) Products Using Unsupervised Feature Learning and Optical Flow Reprinted from: Sensors 2019 ,19, 2605, doi:10.3390/s19112605 .................... 263 Xiangli Huang, Kefeng Ji, Xiangguang Leng, Ganggang Dong and Xiangwei Xing Refocusing Moving Ship Targets in SAR Images Based on Fast Minimum EntropyPhase Compensation Reprinted from: Sensors 2019 ,19, 1154, doi:10.3390/s19051154 .................... 277 Changchong Lu and Weihai Li Ship Classiﬁcation in High-Resolution SAR Images via Transfer Learning with SmallTraining Dataset Reprinted from: Sensors 2019 ,19, 63, doi:10.3390/s19010063 ...................... 
 AES-23, 1987, pp. 438–447. 81. 
 25  5.4 Angular Resolution .......................................................................................................... 26  6 Radar Receiver Noise and Target Detection ...................................................................... 28  6.1 Thermal Noise ................................................................................................................. 
 Dockery, “Modeling electromagnetic wave propagation in troposphere using the para - bolic equation,” IEEE Transactions on Antennas and Propagation , vol. 36, pp. 1464–1470,  October 1988. 
 V . Trunk, “Range resolution of targets,” IEEE Trans ., vol. AES-20, pp. 
 BASED 3!24S BECAUSE THE LATTER ARE DIFFICULT TO DETECT IN ADVERSE CONDITIONS 2ADAR 4ARGET %NHANCERS  2ADAR TARGET ENHANCERS  24%S  ARE USED INCREAS 
 This phenomenon is called space charging. Note that although an increasing number of clutter returns are received during the charging period, the vector sum may actually decrease owing to the random phase relations of the returns from different patches. 6 CiB CLUTTER WIDTH PRF FIG. 
 Such a radar is called monostatic. A bistatic radar is one in which the  tran,mitting and receiving antennas are separated by a considerable distance (Fig. 14.12). 
 TRACK RANGE LINE MUST BE SAMPLED AT LEAST ONCE 5SUALLY THE 02& LOWER BOUND IS SET SO THAT THERE IS A MARGIN OF  OR MORE WITH RESPECT TO THIS CONSTRAINT )N AN AIRBORNE 3!2  THE 02& CONSTRAINT IS DERIVED TO SATISFY THE DOPPLER BANDWIDTH   FROM WHICH FOLLOWS THE MAXIMUM RANGE THAT THE RADAR CAN OPERATE WITHOUT INTRODUC 
 TER FROM MASKING SMALL MOVING TARGETS  THE SIGNAL PROCESSOR MUST ACHIEVE LOW PULSE COMPRESSION TIME SIDELOBES AND HIGH CLUTTER CANCELLATION RATIO !S A RESULT  IT IS MUCH EASIER TO DESIGN A SOLID 
 AP-21, pp. 309-313, May, 1973.  22. 
    . {°{Ó  2!$!2 (!.$"//+  &)'52%   #ONCEPT OF ECLIPSING AND RANGE GATE STRADDLE LOSS 4HE TOP ROW OF PLOTS SHOWS THE TRANSMIT PULSE FOR A SINGLE )00 OF A PULSE DOPPLER WAVEFORM WITH A  DUTY CYCLE OF  4HE SECOND ROW  OF PLOTS SHOWS THE RELATIVE VOLTAGE OF THE MAXIMUM PULSE MATCHED  FILTER -&  OUTPUT AS A FUN CTION OF RANGE 
 ALiterature Survey. GeorgiaIllstitl/le of'Techlloloy,I' RadaramiIllStrlllllelltatioll Lahoratory, Atlanta. Ga.,sponsored by Western CottonResearch Laboratory. 
 FREE REGION IN HIGH 02& !S AN EXAMPLE  &IGURE  SHOWS THE CLUTTER 
 This maximizes processing yield and hence minimizes com- ponent cost. Gate lengths for devices in the 1- to 30-GHz range may vary from 2.0 (Jim to as little as 0.25 jxm. While frequency limits can be increased to some degree by decreasing the gate length, increases in power output require greater transistor gate width to support the increased current flow; however, if gate fingers are made too wide, the microwave signal will accumulate a phase shift and will be attenuated while propagating down the gate metal; con- sequently, the overall gain will be degraded. 
 MM 
 14.4 HEIGHT-FINDER AND JD RADARS  1 n many applications a know ledge of target height might not be needed. An obvious example  is where the target is known to lie on the surface of the earth, and its location is given by the  range and azimuth coordinates. However, there are other instances in which the target's  position irilthrce dimensions must be known. 
 RANGE AIR SURVEILLANCE  SHORT 
 IRE , vol. 41,  pp. 1778–1784, December 1953. 
 PLES INTEGRATED IS  .  THE NUMBER OF EXTRANEOUS NOISE SAMPLES INTEGRATED IS  -  AND THE  COLLAPSING RATIO Q   .   - . L -OST AUTOMATIC DETECTORS ARE REQUIRED NOT ONLY TO DETECT TARGETS BUT ALSO TO MAKE ANGU 
 (v) Spectrum monitoring receivers to locate clear channels for  possible use and to assess their properties. A detailed description of the suite of auxil - iaries for the Jindalee radar can be found in Earl and Ward.149,150 Traditionally, the control mechanism has been the expert radar operator. For many  reasons, this is not wholly satisfactory, so various alternatives have been explored,  including packaged “recipes” that can be invoked by less skilled operators and expert  systems implemented with artificial intelligence constructs. 
 If, for example, the element spacing were 0.5A0 and l/d = 15, the beam can be scanned from  0, = 0 to 6, = 62". (This assumes the lowest frequency is determined by the condition that the  element spacing be not less than one-half wavelength.) With d = 0.6A0, the beam can be  scanned from - 48" to + 36" without the appearance of grating lobes, for l/d = 15.  300INTRODUCTION TORADAR SYSTEMS Lid= 1 110 105 -20° - -80°70° 60°- -'!! 0" --- C 0 C 0 U (J)30°_. 
  AND 8 
 WAVELENGTH MOVEMENTS IN THE LINE 
 Pye receiver R.3070B with tuning control and local/remote indicator switch [ 7]. Figure 2.11. E K Cole receivers, with tuning control and local/remote indicator switch. 
 SURFACE PROFILING BY IMPULSE RADAR v IN  0ROC #ONF 3UBSURFACE  %XPLORATION FOR 5NDERGROUND %XCAVATION AND (EAVY #ONSTRUCTION   !MER 3OC #IV %NG     PP n   0 + +ADABA  h0ENETRATION OF  '(Z TO  '(Z ELECTROMAGNETIC WAVES INTO THE EARTH SURFACE  FOR REMOTE SENSING APPLICATIONS v IN 0ROC )%%% 3% 2EGION  #ONF    PP n   * # #OOK  h3TATUS OF GROUND 
 The mag- nitude of this splash cross section rose to a a° of about -40 dB, corresponding to wind-induced cross sections at this grazing angle for winds of about 10 kn. Fur- ther laboratory58 and theoretical59 studies have shown that the major scattering feature is the vertical stalk that emerges shortly after drop impact. Moreover, these studies suggest that the V-polarized returns from raindrop splashes should be relatively insensitive to the rain rate, while the //-polarized returns should show a strong dependence on both the rain rate and the drop-size distribution. 
 although it was fully supported by the NRL administration. By 1932 the equipment was  demonstrated to detect aircraft at distances as great as 50 miles from the transmitter. The NRL  work on aircraft detection with CW wave interference was kept classified until 1933, when  several Bell Telephone Laboratories engineers reported the detection of aircraft during the  course of other experiments.5 The NRL work was disclosed in a patent filed and granted to  Taylor, Young, and Hyland6 on a•• System for Detecting Objects by Radio." The type of radar  described in this patent was a CW wave-interference radar. 
 3 1. Stark, L., R. W. 
 Dashedcurve,constant prf;solidcurve,staggered prf's.(FromZverev,22 Courtesy IEEE.). tlie same weightings, but with 4 interpulse periods of - 15 percent, - 5 percent, f 5 percent,  and + 15 percent of tile fixed period. The response at the first blind speed of the fixed period  waveform is down only 6.6 dB. 
 (ii) Except for summer, night losses are only slightly less than day losses. (iii) Night noise is much greater than day noise. (iv) For a specific range, optimum frequencies vary by 3:1. 
 One way to avoid this  is to invert the target and tilt the rotation axis toward the radar instead of away from  it. This requires the installation of the rotator in the top of the target as well as in the  bottom. The unused internal cavities created for such installations must be concealed  by covers or shields. 
 12.12. To evaluate cr° the ratio of transmitted to received power is required. The system in Fig. 
 R. Nitzberg, “Clutter map CFAR analysis,” IEEE Trans. , vol. 
 TIONS OF A COHERENT RANDOM NOISE RADAR v /PTICAL %NGINEERING     PP n  *UNE   * 3ACHS  0 0EYERL  & 4KAC  AND - +MEC  h$IGITAL ULTRA 
 (11.11) is measured from the surface patch dS to the point at which the scattered fields are desired. These expressions state that if the total electric and magnetic field distributions are known over a closed surface 5, the scattered fields anywhere in space may be computed by summing (integrating) those surface field distributions. The surface field distributions may be interpreted as induced electric and mag- netic currents and charges, which become unknowns to be determined in a solu- tion. 
 ch24.indd   7 12/19/07   6:00:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures. 
 The optimum bandwidth for angle tracking is range-dependent. A target with typical  velocity at long range has low angle rates and a low SNR, and a narrower servo passband  will follow the target with reasonably small tracking lag while minimizing the response  to receiver thermal noise. At close range, the signal is strong, overriding receiver noise,  but target angle scintillation errors proportional to the angular span of the target are large. 
 The IF  amplifier is also of importance in mixer design because of its influence on the overall  noise-figure.  Conversion loss and noise-temperature ratio. The conversion loss of a mixer is defined as  L = ~~~i!~~l: RF power  c available IF power (9.11)  It is a measure of the efficiency of the mixer in converting RF signal power into IF. 
 633-640, April, 1966.  102. Skolnik, M. 
 D. Cross, D. Howard, M. 
 TO 
 The equation fe = DJ(4 tan i|/^2) (6.21) defines the equivalent focal length, and the magnification m is given by m=fjfm = (e+ DKe- 1) (6.22) Thus the feed may be designed to produce suitable illumination within subtended angles ±i|/r for the longer focal length. Typical aperture efficiency can be better than 50 to 60 percent. Aperture blocking can be large for symmetrical Cassegrain antennas. 
 Thiscondition iscalledsuperre!raetion, ordueting,andisaformofanomalous propagation. Itisnotnecessarily adesirable conditio'n sinceitcannotbereliedupon.Itcandegrade the performance ofMTIradarbyextending therangeatwhichgroundclutterisseen.. Thepresence oftheearth'ssurfacenotonlyrestricts thelineofsight,butitcancause majormodification ofthecDverage withinthelineofsightbybreaking uptheantenna elevation patternintomanylobes.Energypropagates directlyfromtheradartothetarget,but therecanalsobeenergythattravelstothetargetviaapaththatincludes areflection fromthe ground.Thedirectandground-reflected wavesinterfere atthetargeteitherdestructively or constructively toproduce nullsorreinforcements (lobes).TheJobingthatresultscausesnon­ uniform illumination ofthecoverage, andisanimportant factorthatinfluences thecapability ofaradarsystem. 
 ANGLE SEA CLUT 
 WEIGHTED FOUR 
 Tllis cffcct will generally be less severe over land than over  water hccausc of the snlaller reflection coefficient of land. If the antenna beam can be tilted up  so as to rcdircc the illir~nination of the surface, or if the antenna elevation pattern can be  designed to have a sllarp cutoff on the underside of the beam, the effect of surface reflections is  reduced and the nionopulse angle measurement is improved. However, this reduces the cover-  age of targets at low elevation angles. 
 TO 
  
 Steyskal, “Digital beamforming antennas: an introduction,” Microwave J ., pp. 107–124,  January 1987. 88. 
 (/2):/. 2!$!2   Óä°{Î !S REMARKED EARLIER  THE MAXIMUM FREQUENCY THAT WILL REFLECT ENERGY BACK TO THE  %ARTH DURING THE DAY MAY BE MORE THAN TWICE THAT AT NIGHT THEREFORE  THE OCCUPANCY  TENDS TO BE DENSER AT NIGHT THAN DURING THE DAYA PROBLEM COMPOUNDED BY THE LOWER ABSORPTION AND  HENCE  RECEPTION OF MORE DISTANT SIGNALS ,OOKED AT OVER LONGER TIMESCALES  VARIOUS PATTERNS AND TRENDS EMERGE -OST OBVI 
 tile repeater "steals" the radar tracking circuits from the target. The delay between  tllc true cclio arid tlie false eclio car1 be lengtlieried or shortened to sucli an extent that the  OTHER RADAR TOPICS551 Aradarequation fordetecting atargetinthepresence ofjamming noiselargecompared toreceivernoisecanbederivedbysubstituting thejammer noisepowerperhertzreceived at. theradarforthereceivernoisepowerperhertz,orkToFn•Thejammer noisepowerperhertz attheradaris (14.29) whereA..=effective receiving aperture oftheradarantenna andR=rangeofjammer from radar.Substituting Eq.(14.29)forkl;)F ninEq.(2.54),theradarequation forasearchlighting ortracking radar,yields 11\"(J,(oE j(II) (TBj Hl1lox=4(SIN)'j>.C;.Tr !I))(14.30) (14.31)\",here (II=Iliff'=integration time.Thesystemlosseshavebeenomitted. 
 These measurements accumulate, provid - ing unique synoptic data that have revolutionized our knowledge and understanding  of both global and local phenomena, from El Niño to bathymetry. SBR altimeter data  also provide measurements of significant wave height and wind speed. Although one  might consider altimeters to be relatively simple one-dimensional (range measure - ment) instruments, their phenomenal accuracy and precision requires elegant micro - wave implementation and innovative signal processing. 
 Itshould beborne in mind, however, that with toosmall abandwidth, asignal farinexcess of the limit level has amuch greater duration after limiting than has a weak signal. Contrast.—The contrast ofthe display depends upon the character- istics ofthe screen and upon the way inwhich itisexcited. Unfortu- nate ypresent tubes ofthe persistent type have serious shortcomings in contrast. 
 Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration.  AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 tenth percentile. Furthermore, one can use feedback based on several scans of data  to control K in order to maintain a desired Pfa on either a scan or a sector basis. 
 (19) The sidelobes beyond kth with lower energy will contribute little, whether they are relocated in or out the [−h,h]in elevation. 44. Sensors 2019 ,19, 2764 The ﬁrst to kth azimuth sidelobes up to and including the kth will be suppressed if (17) and (19) are met. 
 The backscattering coe ﬃcient is also neglected. Rpand S(θ,f) can be rewritten as a current frequency in a frequency domain: Rp=⎭radicalbigg R2 0+r2−2r⎭radicalBig R2 0−h2cosθ (6) S(θ,f)=rect(θ/θbw)·rect(f/Br)·exp[−j4π(f+fc)Rp/c] (7) TM (a) Geometric model of ArcSAR system in 3-D space ( b) Side view of ArcSAR geometric model  Figure 1. Cont . 
 857–865, 1999. 81. R. 
 33, pp, 83--96, April, 1956.  33. Wylic, F. 
 Virtual height is defined as the speed of light times the time delay for the ionospheric echo; true height is the actual distance to reflection height. The critical frequency is the highest frequency that is reflected. Reference 46 has a figure that illustrates how the stored median ionosphere com- pares with a set of actual soundings; it is shown here as Fig. 
 The amplitudes of the signals in each aper - ture are the same so that the output of the  angle-error phase detector is determined  by the relative phase (see Figure 9.11). The  phase-detector circuit is adjusted with a  90° phase shift on one channel to give zero  output when the target is on axis and an  output increasing with increasing angular  displacement of the target with a polarity  corresponding to the direction of error. Typical flat-face corporate-fed phased  arrays compare the output of halves of the  aperture and fall into the class of phase- comparison monopulse. 
 L.: Estimating the Effect of Feed Support Member Blocking on Antenna Gain and Side  Lobe Level. Microwai·e J., vol. 7, pp. 
 PULL AMPLIFIERS MAY BE BIASED IN THIS FASHION SUCH THAT ONE TRANSISTOR OPERATES OVER THE POSITIVE INPUT SIGNAL SWING  AND THE SEC 
 SIGNAL 
 Partial camouflage oftargets has been achieved byproper shaping. 3“7. Use ofAbsorbent Materials.—The possibility ofreducing the radar cross section bytheuseofmaterials absorbent atradar frequencies hasbeen thesubject ofconsiderable investigation. 
 In terms of stability requirements, the  system requirements are derived using gated phase noise, which in turn is converted to  a CW value for specifying components such as oscillators. The CW phase noise floor  is smaller by a factor of the ratio of the PRF to the transmit bandwidth when the CW  phase noise is assumed to be white. Sensitivity loss due to phase noise is quantified by the increase in the system noise  floor in the “clutter-free” doppler filters due to the phase noise sidebands on a large  signal such as main-beam clutter. 
 5. Daley, J. C., J. 
 VI. In the following sections, the reported comparisons of these radars are discussed and their performance is assessed in the light of modernradar modelling methods. 7.3.1 Comparative trials The best comparison of performance of ASV III and ASV Mk. 
 Dunn, J. H., and D. D. 
 The pulse rate above the  threshold improved the additive SNR, but did not contribute to speckle reduction. The  PRF statistical independence limit decreases with increasing significant wave height. Jason-1. 
 Pieraccini, M.; Miccinesi, L.; Rojhani, N. A GBSAR Operating in Monostatic and Bistatic Modalities for Retrieving the Displacement Vector. IEEE Geosci. 
 REFERENCES I.Weil,Thomas A.:Transmitters, Chap.7ofthe..RadarHandbook," M.LSkolnik (cd.).McGraw-Hili BookCo.,NewYork,1970. 2.Boot,H.A.H.,andJ.T.Randall: TheCavityMagnetron, J.Inst.Elect.Eng.,vol.93,pt.lilA, pr.928-938, 1946. 3.Wathen, R.L.:Genesis ofaGenerator: TheEarlyHistory oftheMagnetron, J.Franklin Inst., vol.255,pp.271-288, April,1953. 
 (ILL    % & %WING  h4HE APPLICABILITY OF BISTATIC RADAR TO SHORT RANGE SURVEILLANCE v IN  )%% #ONF  2ADAR   0UBL   ,ONDON    PP n  % & %WING AND , 7 $ICKEN  h3OME !PPLICATIONS OF "ISTATIC AND -ULTI 
 diameter eccentric disks which serve. 304 ANTENNAS, SCANNERS, ANDSTABILIZATION [SEC, 916 tomake thewavelength less intheline than infree space. This shaft is displaced from theaxis oftheouter conductor and supported bybearings at10-in. 
 For the privilege of independently controlling the time and frequency accuracy with a  periodic waveform, additional peaks occur in the ambiguity diagram. These peaks cause  ambiguities. The total volume represented by the shaded areas of the ambiguity diagram for  the periodic waveform approximates the total volume of the ambiguity diagram of the single  pulse, assuming that the energy of the two waveforms are the same. 
 A rather wide video bandwidth (atleast aswide asthetotal i-fbandwidth) isnecessary when thefrequent yofthejamming signal isnotthesame as that oftheradar transmitter. Use ofalinear detector will also give the i-famplifier agreater dynamic range. Insome receivers itisnecessary toapply a“gate,” which sensitizes thereceiver during acertain interval oftime. 
 TRACING CODES ARE VERSATILE AND ABLE TO ACCOMMODATE ALMOST ARBI 
 MULTIPLEXING THEM TO COVER ONLY THE CURRENTLY ILLUMINATED SURVEILLANCE SECTOR   &)'52%   "EAM SCAN 
 A comparison of MTI and pulse doppler radars is shown in Table 17.2. TABLE 17.1 Pulse Doppler Applications and Requirements TABLE 17.2 Comparison of MTI and Pulse Doppler (PD) Radars Pulse Doppler Spectrum. The transmitted spectrum of a pulse doppler radar consists of discrete lines at the carrier frequency /0 and at sideband frequencies /o ± (//?> where/^ is the PRF and i is an integer. 
 D. Badhwar, and E. Reyna, “The Use of a helicopter mounted ranging scat - terometer for estimation of extinction and scattering properties of forest canopies,” IEEE  Trans. 
 DOMAIN CONVOLUTION PROCESSOR THAT WILL PRO 
 Atlas and E. Kessler III, “A model atmosphere for widespread precipitation,” Aeronaut. Eng. 
 Electron emission inhigh-power crossed-field amplifiers cantakeplacebycold-cathode emission withoutathermally heatedcathode. Someoftheelectrons emittedfromthecathode arenotcollected bytheanodebutreturntothecathode bytheactionoftheRFfieldandthe crossedelectricandmagnetic fields.Whentheseelectrons strikethecathode theyproduce secondary electrons thatsustaintheelectronemission process.Cold-cathode emission requires thepresence ofboththeRFdrivesignalappliedtothetubeaswellasthed-cvoltagehetween cathodeandanode.Thebuildupofthecurrentbymeansofthissecondary emission processis veryrapid(withinnanoseconds). Thereislittlepulse-to-pulse timejitterinthestartingprocess. 
 r 
 Trunk5 © IEEE 1972 ) ch07.indd   3 12/17/07   2:12:52 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Automatic Detection, Tracking, and Sensor Integration. 
 Anisotropic radiator would spread the same power over asolid angle of4T. Therefore, weexpect thegain tobeapproximately 4rd2/X’, which isconsistent with Eq. (1),since thearea oftheaperture isabout d’.For amore rigorous discussion ofthese questions the reader isreferred to Vol. 
 Antenna noise is the result of (1) noise in the form of electromagnetic waves received by the antenna from external radiating sources and (2) thermal noise generated in the ohmic components (resistive conductors and imperfect insulators) of the antenna structure. The product kT0Bn is the noise power available at the antenna terminals within the receiver bandwidth. This noise temperature is dependent in a somewhat complicated way on the noise temperatures of various radiating sources within the receiving-antenna pat- tern, including its sidelobes and backlobes. 
 This would notbe adequately addressed until well after WWII, and needed, amongst other things, high power 3 cm ASV systems with large antenna apertures and short pulse lengths. Techniques investigated on ASV Mk. X during WWII included the use of a shortAirborne Maritime Surveillance Radar, Volume 1 8-4. 
 7977, Mar. 16, 1976. 15. 
 324 THE MAGNETRON AND THE PULSER [SEC. 10.1 same LCbut different L/C.Itshould benoted that thearrangement of these cavities issuch that forthe desired mode ofoperation their indi- vidual C’sareconnected inparallel, and soaretheir individual L’s.Thus theeffective capacitance forthewhole magnetron oscillator isNC and the effective inductance isL/N,where Nisthe number ofresonators. The frequency ofthe magnetron isthus nearly that ofanindividual cavity. 
 87–89. 39. P. 
 SITE  RECEIVER 
 11.7. The connectors match the 50-ohm impedance ofthe cable at10-cm and longer wave- lengths. The mismatch at3cmisnot great. 
 In the worst case, submarine targets could only be detected at ranges Figure 2.1. Transmit and receive antennas on a Hudson (adapted from image of Hudson by Kaboldy (Own work) [CC BY-SA 4.0 ( https://creativecommons.org/licenses/by-sa/4.0 )]).Airborne Maritime Surveillance Radar, Volume 1 2-2. between 4 ½ and 5 ½ miles. 
 RANGE DETECTION OF SATELLITES AND DEFENSE AGAINST INTERCONTINENTAL BALLISTIC MISSILES 3 BAND  TO  '(Z   4HE !IRPORT 3URVEILLANCE 2ADAR !32  THAT MONITORS  AIR TRAFFIC WITHIN THE REGION OF AN AIRPORT IS AT 3 BAND )TS RANGE IS TYPICALLY  TO  NMI )F A $ RADAR IS WANTED ONE THAT DETERMINES RANGE  AZIMUTH ANGLE  AND ELEVATION ANGLE   IT CAN BE ACHIEVED AT 3 BAND )T WAS SAID PREVIOUSLY THAT LONG 
 The radar look direction was 180◦, and the other parameters were the same as those described in Section 4.1, as shown in Table 6. The simulated SAR images under the four different wind directions are given in Figure 14. 323. 
 KM SWATHS 4HE ARRAY IS PARTITIONED IN THE ALONG 
 TheSkiatron.—The dark-trace tube, described briefly inSec. 13”2, has been used asthebasis forareasonably successful projection system both inEngland and inAmerica, the principal differences being inthe optical systems used. InEngland, anextremely flat-faced tube serves asthe source forawide-aperture lens system; inthis country atube has been designed tofitaSchmidt optical system. 
 Instead, the  first stage is simply the mixer. Although the noise figure of a mixer front-end may not be as low  as other devices that can be used as receiver front-ends, it is acceptable for many radar  applications when other factors besides low noise are important. The function of the mixer is  to convert RF energy to IF energy with minimum loss and without spurious responses. 
 Percival, “Joint ionospheric and track target state estimation for multipath  othr track fusion,” Proc. SPIE Conf. on Signal and Data Processing of Small Targets , 2001,   pp. 
 BASED 3!2 IS IMAG 
 This can be used directly, but it is convenient to define the  Excess Power at each frequency as follows. Suppose: • An SNR threshold of M dB is required before the signal processing will register a  detection and • The SNR calculated for a particular range-azimuth cell in the coverage is SNR( f )  dB (which may be negative) Then, in dB,  Excess Power ( f ) = M − SNR( f ) + PT − PREF  is the amount of extra power, relative to any chosen reference power PREF , needed to  achieve detection as a function of frequency. A negative value indicates that the radar  has greater sensitivity than required. 
 3.6 Effect of 15-jxs range delay on stalo MTI limitation. NOISE LEVEL (dBc/Hz) FREQUENCY (kHz) FIG. 3.7 Effect of 1200-^s range delay on stalo MTI limitation. 
 Desert, forests, vegeta-  tion, bare soil, ci~ltivated fields. mountains, swamps, cities, roads, and lakes all have different  scattering characteristics. Furtherrnore, the radar echo will depend on the moisture content of  tlie surface scatterers, snow cover, and the stage of growth of any vegetation. 
 65.Mertens, L.E.,andR.H.Tabeling: Tracking Instrumentati)n andAccuracy onthe;Eastern Test Range,IEEETrans.,vol.SET-ll, pp.14-23,March,1965. 66.McCaskill, T.8.,J.A.Buisson, andD.W.Lynch:Principles andTechniques ofSatellite Navigation UsingtheTimation IISatellite, NavalResearch Laboratory Rep.7252,June17,1971,Washington, D.C. 67.Easton, R.L.:TheRoleofTime/Frequency inNavyNavigation Satellites, Proc.IEEE,vol.60, pp.557-563, May,1972. 
 Geosci. Remote Sens. 2014 ,52, 2773–2779. 
  D"  SINCE 3.2 y  
 5 cascaded &le-tuned  stages ' .  Optimum Br  1.37  0.72 0.72  0.44  0.4  0.613  0.672  374INTRODUCTION TORADAR SYSTEMS L0 9r--r-....-.,--,---,----,----.,------r----r-,--..-,..---,----,-r ,--T-TT]11I-'I w- ~08 w.cu007­ E o-t;0.6 w0. '"t:'O.S- ~ L0.4- <U- 003 >­uc: .~02u .....w "0.1-Rectangula r­ shapedpassband --Single-tuned (RLC) resonant passband 1.0 2.0 3.0 40 Holt-power bondw'ldth timespulsewidth, BT50J Figure10.2Efficiency, relativetoamatched filter,ofasingle-tuned resonant filterandarectangular shapedfilter,whentheinputsignalisarectangular pulseofwidthr.B=filterbandwidth. 
 (Copyright 1970, IEEE.1*) Figure 11.18 charts the RCS of a ship measured at 2.8 and 9.225 GHz at hor- izontal polarization. The data was collected by a shore-based radar instrumenta- tion complex as the ship steamed in a large circle on Chesapeake Bay. The three traces in these charts are the 80, 50, and 20 percentile levels of the signals col- lected over aspect angle "windows" 2° wide. 
 But the Fourier transform ofaFourier transform isthefunction itself, and sowefind the interesting theorem that thefrequency spectrum due toscanning hasthe same form asthe function representing the illumination ofthe dish. Actually, the above statement represents aslight oversimplification because wehave assumed that the antenna directivity enters only once whereas actuallyitenters twice, once inthe sending process and once inthe receiving. Taking this into account and carrying out the cal- culation, wefind that the spectrum due toscanning, which weshall call g(u), isgiven by . 
 The ensemble average power pattern'of a uniform array of M by N isotropic elements  arranged on a rectangular grid with equal spacing between elements can be expressed as1''  where P, = probability of an element being operative (or the fraction of the elements that  remain working)  6 = phase error (described by a gaussian probability density function)  I .fo(U, 4))' = no-error power pattern  A = amplitude error  i,, = no-error current at the mnth element  Thus the effect of random errors is to produce an average power pattern that is the superposi-  tion of two terms, similar to Eq. (7.31) for the continuous aperture. The first term represents  the no-error power pattern multiplied by the square of the fraction of elements remaining and  by a factor proportional to the phase error. 
   ON  OPERATIONAL  AND  TECHNICAL  PERFORMA NCE  REQUIREMENTS  FOR   643 %QUIPMENT v %DITION   )NTERNATIONAL !SSOCIATION OF ,IGHTHOUSE !UTHORITIES )!,!   0ARIS    h)NTERNATIONAL MEETING ON RADIO NAVIGATION AIDS TO MARINE NAVIGATION  -AY  v VOL   2ECORD  OF THE MEETING AND DEMONSTRATIONS  (IS -AJESTYS 3TATIONERY /FFICE  ,ONDON  . ÓÎ°£ ÃÌ>ÌVÊ,>`>À  V >ÃÊ°Ê7Ã 4ECHNOLOGY 3ERVICE #ORPORATION RETIRED  ÓÎ°£Ê  " 
 89. Trunk. G. 
 FREQUENCY CHARACTERISTICS %SSENTIALLY  THE LATTER CLASS WILL CAUSE THE DIFFERENT FREQUENCY COMPO 
 65 ).  Analog delay lines that have been used in such devices include acoustic lines, lumped­ parameter delay lines, electrostatic storage tubes, and magnetic drums or disks'. They do not  have, in general, sufficient stability to permit large values of k. 
 N. Anderson, “PIM model 1995,” http://modelweb.gsfc.nasa.gov/ ionos/pim.html. 39. 
 The picture on the right shows the MTI clutter rejection. The camera shutter was left open for three scans of the antenna; thus aircraft show up as a succession of three returns. MTI radar utilizes the doppler shift imparted on the reflected signal by a mov- ing target to distinguish moving targets from fixed targets. 
 TRACKING ALGORITHMS PRODUCE SIMILAR NUMBERS OF FALSE TRACKS (OWEVER  THE BACKWARD 
 20.1  20.1 Height Finding Radars and Techniques   .................  20.1  Early Radar Techniques for Height Finding  ........  20.1  Height Finding Techniques in 3D Radars  ........... 
 The five-pulse canceler response shown is a linear-phase21 MTI filter de- scribed by Zverev.22 The four zeros are located on the Z-plane real axis at +1., + 1., -0.3575, and -2.7972. Much of the literature on filter synthesis describes linear-phase filters, but for MTI applications linear phase is of no importance. Almost identical filter responses can be obtained with nonlinear-phase filters that require fewer pulses, as shown in Fig. 
 Although the theoretical  tolerance of a lens may be less than required of a reflector, in practice it might be more difficult  to achieve a given level of performance in a lens. A reflector can be readily supported mechan­ ically from the back. This is not available in a lens where the mechanical support is from the  periphery of the lens and from the mechanical properties of the lens material itself. 
 ING FUNCTIONS SUCH AS DIGITAL DOWNCONVERSION AND PULSE COMPRESSION  FOLLOWED BY PROGRAMMABLE PROCESSORS IN THE REAR  PERFORMING THE LOWER 
 Tournois, “Signal processing using surface-acoustic-wave and digital compo - nents,” IEEE Proc ., vol. 127, pt. F, pp. 
 TO 
 A significant restriction in attempting to utilize solid-state devices as a direct replacement  for the conventional microwave-tube transmitter is the relatively low power available from a  single solid-state device or even a single power module. The solid-state device or module finds  application in those radars where high power is not needed, such as aircraft altimeters. CW  police speedmeters, and short-range intrusion detectors. 
 BAND SPURIOUS OUTPUT IS AFFECTED BY TUBE AND MODULATOR SELECTION  BUT IT CAN BE FILTERED BY A HIGH 
 In fact,  MTBF for the output power transistors measures better than 1.1 million hours. 11.3 SOLID-STATE DEVICES Although the RF power-generating capability of single transistors is small with  respect to the overall peak and average power requirements of a radar transmitter,  transistors are used quite effectively by combining the outputs of many identical  solid-state amplifiers. The power output level from a particular device is a function  of not only the chosen technology, but also the frequency and other conditions, such  as pulse width, duty cycle, ambient temperature, operating voltage, and the presented  load impedance. 
 Overview.  The surface-height measurement objectives of space-based altimeters  can be grouped into four broad categories: large-scale dynamic sea-surface topogra - phy, dynamic mesoscale* oceanic features, static mesoscale sea-surface topography,  and ice—sea ice as well as continental ice sheets. Each of these measurement themes  implies narrowed constraints on choice of orbit and on the top-level instrument and  mission design. 
 FREQUENCY AMPLITUDE NOISE CONTRIBUTES THE  LARGEST PORTION OF THE NOISE MODULATION DENSITY AND IS CONCENTRATED MAINLY BELOW ABOUT  (Z AT 8 BAND 4HE AMPLITUDE 
 DiBartolo, J., W. J. Ince, and D. 
 Yakunin, F. F. Evstratov, F. 
 •  Cooling system  design to  maintain feed  temp can be a  challenge.•  Can be a major  driver. •  Radars are  typically high  power. •  High power  densities at feed  or feed array are  common. 
 and the phase spectrum of the matched filter is the negative of the phase spectrum of  the echo signal (Sec. 10.2). In a radar whose signal waveform approximates a rectangular  pulse, the conventional IF filter bandpass characteristic approximates a matched filter when  the product of the IF bandwidth Band the pulse width r is of the order of unity, that is, Br ~ 1. 
 SPEED  HIGH 
 MIZED VIA RAY TRACING  AND IS FORWARD OF THE AZIMUTH FOCAL POINT &OR EACH ROW  THE AMPLITUDE AND PHASE IS OPTIMIZED FOR A BEAM WITH LOW AZIMUTH SIDELOBES 4HE ELEVATION PATTERNS FOR EACH SINGLE ROW HAVE POOR SIDELOBES  BUT SEVERAL ROWS ARE USED FOR EACH RECEIVE BEAM THEREBY IMPROVING THE ELEVATION SIDELOBES &OR TRANSMIT  ALL  ROWS THE WHOLE ARRAY  ARE USED /N RECEIVE   GROUPS OF ROWS ARE USED TO FORM  RECEIVE BEAMS &)'52%   %XTENDED FEED REGION IMPROVES SIDELOBES OF OFFSET FEED USED ON  !232 
 * Multistatic cross-range location can be more accurate than monostatic or bistatic  cross-range location since angle data, with its range-dependent accuracy, is not used. The  multistatic radar must, however, use multiple, properly located sites with both overlap - ping coverage and simultaneous measurements, which, in turn, require broad transmit and  receive beams to achieve this accuracy. These requirements usually combine to restrict  multistatic air surveillance performance to short or medium ranges. 
 QUENCY  SO THE OUTPUT SPECTRUM CAN BE OBTAINED BY COMBINING THE RESPONSES OF THESE FILTERS WITH THE SPECTRUM PRESENT AT THE MIXER INPUT )N -4) SYSTEMS  IT IS COMMON TO DESCRIBE THE ABILITY TO SUPPRESS CLUTTER IN TERMS OF AN -4) IMPROVEMENT FACTOR 4HE -4) IMPROVEMENT FACTOR ) IS DEFINED AS THE SIGNAL 
 however, is still large.) Thus laser radars operating in the  infrared and visihle regions achi'cve·the advantages of high angular resolution, wide bandwidth, ·  and doppler frequency sensitivity without the accompanying disadvantage or high attenuation  as experienced in the submillimeter region. Because or its small physical aperture a laser radar  is not suited for most surveillance applications. It is, however, well suited for precision measure­ ment and target imaging. 
 The full 360 °  azimuthal pattern sees velocities from −Vg to +Vg. The compensation circuits offset  the velocity by an amount corresponding to the antenna boresight velocity VB, but the  total range of doppler frequencies corresponding to 2 Vg is obtained because of echoes  received via the sidelobes. For airborne systems with low PRFs, these doppler fre - quencies can cover several multiples of the PRF so that the sidelobe power is folded  into the filter. 
 DELAYCANCELLATION  A   )'D '4 'PSCAN 
 l'lic anloutit of niccliitriical motion of the tuning element need not be large (perhaps a  fraction of an inch at L band) to tune the frequency over a 5 to 10 percent frequency range. A  frequency cliange in a converitional magnetron can also be obtained with a change in capacity.  Otie example is the cookie cutter, which consists of a metal ring inserted between the two rings  of a double-ring-strapped magnetron, thereby increasing the strap capacitance. 
 STATE TRANSMITTER REPLACING A KLYSTRON TRANSMITTER  L 'RACEFUL DEGRADATION OF SYSTEM PERFORMANCE OCCURS WHEN INDIVIDUAL MODULES FAIL  0OWER OUTPUT DEGRADES BY  LOG n A  AS DEVICES FAIL  WHERE  A  IS THE FRACTION OF  FAILED DEVICES 4HIS RESULTS BECAUSE A LARGE NUMBER OF SOLID 
 An Improved range Model and Omega-K-Based Imaging Algorithm for High-Squint SAR with Curved Trajectory and Constant Acceleration. IEEE Geosci. Remote Sens. 
   NO  PP n   *ANUARY   0 0 'ANDHI AND 3 ! +ASSAM  h!NALYSIS OF #&!2 PROCESSORS IN NONHOMOGENEOUS BACKGROUND v  )%%% 4RANSACTIONS ON !EROSPACE AND %LECTRONIC 3YSTEMS  VOL   NO   *ULY   * &ARRELL AND 2 4AYLOR  h$OPPLER RADAR CLUTTER v  )%%%  4RANSACTIONS  ON  !ERONAUTICAL    .AVIGATIONAL %LECTRONICS  VOL !.% 
 The processed target detection information or its track might be displayed  to an operator; or the detection information might be used to automatically guide a FIGURE 1.1  Block diagram of a simple radar employing a power amplifier as the transmitter in the upper  portion of the figure and a superheterodyne receiver in the lower portion of the figureDuplexerPower amplifierAntenna Waveform generator Low-noise amplifier MixerLocal oscillatorIf amplifierMatched filterSecond detectorVideo amplifierDisplay ch01.indd   3 11/30/07   4:33:38 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. An Introduction and Overview of Radar. 
 The whole aperture of 360◦is divided into 180 subapertures. Every subaperture is 4◦. The apertures overlap every 2◦. 
 Goldstein, H. A. Zebker, and T. 
 WAVE MICROWAVE CIRCUITRY OF THESE TUBES BECOME SMALLER WITH INCREASING FREQUENCY 4HE SMALLER THE DEVICE THE MORE DIFFICULT IT IS TO DISSIPATE THE HEAT THAT IS GENERATED 4HUS  THE POWER OUTPUT DECREASES APPROXIMATELY INVERSELY AS THE SQUARE OF THE RADAR FREQUENCY 4HE GYROTRON 2& POWER GENERATOR  HOWEVER  DOES NOT HAVE THIS LIMITATION BECAUSE  IT DOES NOT EMPLOY SLOW 
 Such radars are sometimes called blob detectors since they recognize  targets only as "blobs" located somewhere in space. It is possible, however, to extract more  information about the target. Radar may be able to recognize one type of target from another;  that is, to determine that the target is a 747 aircraft and not a DC-10, or that a particular ship  is a tanker and not a freighter. 
 Wicks, “Recent results in space-time processing,” in IEEE National  Radar Conference 1994, pp. 104–109. 32. 
 NOAA Technical Report ERL 283-WPL 26, July, 1973.  40. Craig. 
 Hence, information might be obtained about  some targets that cannot be as readily obtained at lower frequencies (long wavelengths). Also  the cross sections will be greater for those scatterers which are comparable in size to the radar  wavelength. In the millimeter region, however, resonances of the atmospheric constituents are  excited (in particular oxygen and water vapor) which result in attenuation that can be  relatively high, even in the clear atmosphere. 
 FREE  IE  AWAY FROM THE INFLUENCES OF THE %ARTHS ATMOSPHERE AND SURFACE )N FREE SPACE  THE ELECTROMAGNETIC WAVEFRONT FROM AN ISOTROPIC RADIATOR SPREADS UNIFORMLY IN ALL DIRECTIONS FROM THE TRANSMITTER -ULTIPATH )NTERF ERENCE AND 3URFACE 2EFLECTION  7HEN AN ELECTROMAGNETIC  WAVE STRIKES A NEARLY SMOOTH LARGE SURFACE  SUCH AS THE OCEAN  A PORTION OF THE ENERGY IS REFLECTED FROM THE SURFACE AND CONTINUES PROPAGATING ALONG A PATH THAT MAKES AN . 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. MTI Radar.  MTI RADAR  2.456x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 limitation is predominant. 
                   
 As frequency is changed by d  f,  the pattern is scanned. It is shown dashed in a position where it has been scanned by a  little more than half of its beamwidth. This is clearly too much, for the product of array  and element factors gives two beams of equal amplitude. 
 However, whenthereciprocal ofthesignal bandwidth iscomparable withthetimetakenbyaradarwavetotransverse theantenna aperture, bandwidth efTectscanbeimportant andsignaldistortion mayresult. 7.3PARABOLIC-REFLECTOR ANTENNAS Oneofthemostwidelyusedmicrowave. antennas istheparabolic reflector (Fig.7.6).The parabola isilluminated byasourceofenergycalledthefeed,placedatthefocusofthe parabola anddirected towardthereflector surface.Theparabola iswellsuitedformicrowave antennas because(I)anyrayfromthefocusisreflected inadirection paralleltotheaxisof theparabola and(2)thedistance traveled byanyrayfromthefocustotheparabola andby reflection toaplaneperpendicular totheparabola axisisindependent ofitspath.Therefore a pointsourceofenergylocatedatthefocusisconverted intoaplanewavefront ofuniform phase. 
 2018 , 10, 365. [ CrossRef ] 15. Ge, L.L.; Ng, A.H.M.; Du, Z.Y.; Chen, H.Y.; Li, X.J. 
 ERROR 
 2.72  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 values shown in these equations can be replaced by the rms pulse-to-pulse values,  which gives results essentially identical to Steinberg’s results.41 If the instabilities occur at some known frequency, e.g., high-voltage power sup - ply ripple, the relative effect of the instability can be determined by locating the  response on the velocity response curve for the MTI system for a target at an equiva - lent doppler frequency. If, for instance, the response is 6 dB down from the maximum  response, the limitation on I is about 6 dB less severe than indicated in the equations  in Table 2.5. If all sources of instability are independent, as would usually be the  case, their individual power residues can be added to determine the total limitation  on MTI performance. 
 MATING *X X DOWN TO  A y n  WHERE * IS A "ESSEL FUNCTION OF ZERO ORDER ! LINEAR  APERTURE OF LENGTH  $  WITH ASPECT ANGLE ORTHOGONAL TO THE TRANSMITTER ,/3  WILL ROLL OFF   D" AT O  
 [ CrossRef ] 29. Antoin, B.; Josep, P .; Luis, J.; Angel, C. Spherical wave near-ﬁeld imaging and radar cross-section measurement. 
 The diodes are used as switches to control which  bits are activated to achieve a particular phase state. The hybrid-coupled technique uses a microwave hybrid and effectively changes the  distance at which the reflection takes place. This technique is usually used in binary  increments, and an additional set of diodes is required for each phase state. 
 The feed is typically moved in a circular path around the focal point, causing a corresponding movement of the antenna beam in a circular path around the target. A typical block diagram is shown in Fig. 18.4.2 A range- tracking system is included which automatically follows the target in range, with range gates that turn on the radar receiver only during the time when the echo is expected from the target under track. 
  MILITARY AIRCRAFT . 
 TO 
 CIENCY !N ELEMENTAL ANTENNA IS A DIPOLE IN CONTRAST TO APERTURE ANTENNAS SUCH AS HORNS ! NORMAL SHORT DIPOLE ANTENNA FED WITH A VERY SHORT CURRENT IMPULSE WILL RADIATE FROM THE FEED POINTS AND THE END OF THE ELEMENT BECAUSE OF THE LATTERS DISCONTINUITY AS FAR AS CURRENT FLOW IS CONCERNED 4HE CURRENT IMPULSE WILL BE REFLECTED FROM THE END OF THE DIPOLE AND TRAVEL UP AND DOWN THE DIPOLE CAUSING A SERIES OF IMPULSES OF RADIA 
 Ifabeam isdirected into the corner formed bythe planes, triple reflections occur which send itback inthe direction from (a) (b) FIG.32.-Tl1e triangular COI’UCV reflector. which itcame (Fig. 3.2b). 
 BAND RADAR USED FOR AIR TRAFFIC CONTROL AT AIRPORTS 4HE DESIGN OF THE FILTERS IS PRIMARILY FOR -OVING 4ARGET $ETECTOR -4$  DETECTION OF AIRCRAFT  BUT SPECIAL ATTENTION IS GIVEN TO PROVIDING FLAT PASSBAND RESPONSE FOR ACCURATE WEATHER REFLECTIVITY ESTIMATION 4HE FILTER BANK FOR ("7     IS PICTURED IN &IGURE  AND THE COEFFICIENTS ARE SHOWN IN 4ABLE  &)'52%  #LUTTER INPUT AND RESIDUE FROM ELLIPTIC FILTER 2ADAR STARTS RADIATING AT PULSE  NUMBER                
 However, it remains unclear whether human factor works alone or with natural factor. Thus, the roles of natural and human factors in land subsidence require further study. Wuhan city, which is the biggest city in central China, has various types of natural conditions and has experienced rapid urbanization in recent years. 
 Weight savings inrectifier-filter supplies canusually beachieved with 3-phase power, ifthis isimportant. For large mobile systems itiswell toinvestigate availability ofstan- dard U.S. Army power-supply units. 
 In Chap. 2 the radar detection process was described in terms of threshold detection.  Almost all radar detection decisions are based upon comparing the output of a receiver with  some threshold level. 
 II. TypeMean frequency DC Volts Remarks T.3040 176 Mc/s Blower, 24 V Used in ARI 5002 or 5077 T.3040A 176 Mc/s Blower, 12 V Used in ARI 5002 or 5077T.3040B 176 Mc/s Blower, 12 V Small version for Fleet Air Arm, ARI 5008 T.3040D 176 Mc/s Blower, adaptable for 12 V or 24 VOtherwise similar to T.3040, used in ARI 5002 or 5077 T.3040E 176 Mc/s Blower, adaptable for 12 V or 24 VOtherwise similar to T.3040B, ARI 5008 T.3069 214 Mc/s Blower, 12 V Similar to T.3040 A, used in Naval craft Transmitter T.3140 and Modulator, Type 52176 Mc/s Blower, 24 V High-power anode modulated transmitter Table 2.2. Receivers for ASV Mk. 
 This results in the synthetic aperture radar having a two-way antenna pattern  I Conventional antenna /  I / Unfocused SAR /  Focused SAR Figure 143 Comparison of the resolution of a  I I synthetic aperture radar and a radar with a con- ' i 10 100 ventional antenna, assuming an X-band antenna  Range, k m with dimension D = 3. m.  OTHER RADAR TOPICS519 Theresolution oftheunfocused SARdoesnotdependonthesizeoftherealantenna. 
 $ DOPPLER RADARS COMMONLY CALLED .EXRAD RADARS  !LSO IN THE S THE &!! INSTALLED THE 4ERMINAL $OPPLER 7EATHER 2ADAR 4$72  SYSTEM AT  MAJOR AIRPORTS IN THE 53 4HE FEDERAL AGENCIES HAVE SUBSEQUENTLY IMPLEMENTED MANY TECHNICAL UPGRADES TO THE .EXRAD AND 4$72 NETWORKS TO IMPROVE THEIR PERFORMANCE FOR PUBLIC WARNINGS AND AVIATION SAFETY   )N CONTRAST TO THE 732 
 As the means for choosing a and P become more sophisticated, the optimal cx.-P  tracker becomes equivalent to a Kalman filter even for a target trajectory model with error. In  this sense, the optimal rx-P tracking filter is one in which the values of a. and P require  knowledge of the statistics of the measurement errors and the prediction errors, and in which a  and p are determined in a recursive manner in that they depend on previous estimates of the  mean square error in the smoothed position and velocity.79  (The above discussion has been in terms of a sampled-data system tracking targets  detected by a surveillance radar. 
 STATE DEVICES BECAUSE TRANSISTORS EXHIBIT MUCH SHORTER THERMAL TIME CONSTANTS THAN THE REPLACEMENT TUBE AND ARE MORE EFFICIENTLY OPERATED USING A LOWER COMPOSITE PEAK POWER AT A HIGHER DUTY CYCLE !S AN EXAMPLE OF THE DILEMMA  AN , 
 '['lie Kaylcigli p~ol)ability dc~isity lulictio~i its was give11 in Sec. 13.3 is  wl~crc nZ is the Incitn square value of r). 'Tlie Rayleigli pdf lias the property that tlie rrns  arnpliti~tfe oftlie flucti~ations about tlic nieali (detioted by 61)~~) is proportional to the mean Fin. 
 The factor B peaks at points of specular reflection, so Eq. 15.19 expresses the  effects of specular glints as well as sharp curvatures. Although the original theory13  is based on a physical optics formulation for a scalar field (see Sangston111 for the  vector form), some support for its implications can be gained from a plot of the square  of surface curvature over a real sea surface. 
 H.: Tracking of Formation Flying Aircraft. International C01!ference RADAR-77, Oct. 25-28,  1977. 
 Since it only has to cover the  range blanked by the long pulse, it need not be of large power. A separate ~eceiver, or matched  filter, might be needed for this short-range pulse. A pulse-compression waveform does not  have the immunity to repeater jammers or range-gate stealers inherent in the short-pulse  radar. 
 I., and D. D. King: Self-Phasing Arrays, IEEE Trans., vol. 
 16. W. A. 
 ENING 7ILEY EXPLAINED IT AS FOLLOWS h) HAD THE LUCK TO CONCEIVE OF THE BASIC IDEA  WHICH ) CALLED $OPPLER "EAM 3HARPENING $"3   RATHER THAN 3YNTHETIC !PERTURE 2ADAR 3!2  ,IKE ALL SIGNAL PROCESSING  THERE IS A DUAL THEORY /NE IS A FREQUENCY 
 (1 1.16). as well as between the expressions for Sf and STR. The  parameter a is called the efl'ective time duration of the signal, and (a/21t)~ is the normalized  second moment of s2(r) about the mean epoch, taken to be t = 0. 
 It can be seen that it had a large elevation sidelobe around 30°from the mainlobe and a null around 15 °. The possible effect of this is discussed later. Also shown in ﬁgure 3.10is the improved pattern developed for ASV Mk. 
 DESIGNED (ARDWARE  4HROUGH THE S  REAL 
 F. Kretschmer, Jr., “Linear Frequency Modulation Derived Polyphase Pulse  Compression Codes,” IEEE Trans. on Aerospace and Electronics Systems , AES-18, no. 
 SCAN COMPENSATION OF A SINGLE 
  D" AVERAGE LEVEL   
 Forexam­ ple,withN=127,thepeaksidelobe isbetween-18and-19.8dB,insteadofthe-21dB predicted onthebasisofthecodelength.ForN=255,thepeaksidelobe variesfrom -21.3dBto-22.6dB,insteadofthe-24dBpredicted.29 Thebinarycodesgenerated inthismanner fitmanyofthetestsforrandomness. (Ran­ domness, however, isnotnecessari.ly adesirable property ofacodeusedforpulsecompres­ sion.)Thenumberofonesineachsequence dilTersfromthenumberofzerosbyatmostone (thebalanceproperty). Amongtherunsofonesandzerosineachsequence, one-half ofthe runsofeachkindareoflength one,one-fourth areoflengthtwo,one-eighth areoflengththree, andsoon(therunproperty).Ifthesequence iscompared termbytermwithanycyclicshiftof itself,thenumberofagreements dilTersfromthenumberofdisagreements byatmostone(the correlation property). 
 DRIVEN AIRCRAFT IN FLIGHT &IGURE  FROM $UNN  (OWARD  AND +ING ¡ )2%   .   42!#+).' 2!$!2   °Ó IS PRODUCED 4HE BACKGROUND NOISE FROM THE AIRFRAME IS ALSO OBSERVED 4HE SPIKES  IN THE SPECTRUM RESULT FROM A FUNDAMENTAL MODULATION FREQUENCY  RELATED TO THE PRO 
 Each transmitter footprint is analyzed by forming simultaneous contiguous receive  beams, on the order of 1/2 ° wide at 15 MHz in the case of the U.S. Navy ROTHR and  the Australian Jindalee and JORN radars, which equates to a 10 km cross-range resolu - tion at a 1200 km range. The task-specific requirements on DIR revisit rates determine  the sequencing of the DIR interrogations and, of course, set the limit on how many  tasks can be addressed. 
 Sensors 2020 ,20, 1851 scintillation conditions. Simulations allowed investigating the image degradation in azimuth induced by scintillation, and deriving threshold values of scintillation strength and spectral index, which guarantee acceptable P-band spotlight imaging. One of the most relevant characteristics of the ionosphere is the total electron content (TEC), which is investigated in [ 12] by exploiting spaceborne polarimetric SAR (PolSAR) data. 
 Thusthetotalareaof ambiguity, oruncertainty, isthesamenomatterhow'1X(TR,fd)12isdistributed overtheTR,fd plane,asillustrated bythesandbox analogy mentioned earlierinthissection. Thereaderis advised nottobedistracted bytryingtounderstand whythisfunction isdescribed bythe ambiguous useoftheterm"ambiguity." 11.5PULSE COMPRESSION Pulsecompression allowsaradartoutilizealongpulsetoachieve largeradiated energy,but simultaneously toobtaintherangeresolution ofashortpulse.Itaccomplishes thisbyemploy­ ingfrequency orphasemodulation towidenthesignalbandwidth. (Amplitude modulation is 'alsopossible, butisseldom used.)Thereceived signalisprocessed inamatched filterthat. 
 Derr (ed.), Boulder, CO: NOAA/Environmental Research Laboratories, 1972,  pp. 12.1–12.6.  82. 
 Where the direct and indirect waves are exactly ofopposite phase, i.e., the trough of one wave coincides with the crest of theother wave, hyperbolic lines of minimum radiation known as LINES OFMINIMA are produced. Along directions away from the antenna, the directandindirectwaveswillgraduallycomeintoandpassoutofphase,producinglobes of useful radiation separated by regions within which, for practicalpurposes, there is no useful radiation. Figure 1.5 illustrates the lower region of the INTERFERENCE PATTERN of a representative navigational radar. 
 In practical radar applications Qk > 0, and so the tracking gains  eventually settle to a non-zero value termed the steady-state tracking gains. The tradeoffs for employing a Kalman filter for radar tracking generally are tuning  the filter for the desired degree of filtering, selecting the tracking coordinates, and  adapting the filter to deal with changes in the target motion (e.g., maneuvers, different  phases of ballistic flight, and so on). Tuning the Kalman Filter. 
 H., L. C. Young, and L. 
 The first equipments were operated in aircraft as early as 1936 and utilized the same principle  of operation as the FM-CW radar described in Sec. 3.3. In the case of the radio altimeter, the  target is tlie ground. 
 The m MSBs of the running sum are sent to a phase-to-amplitude  converter, which is a lookup table that produces a k-bit value that represents the  amplitude of the sine wave at the input phase. If we represent the tuning word by M,  the sample frequency by fs, and the number of bits in the phase accumulator by n,  then the frequency of the output sine wave can be expressed as Mfs/2n. In this scheme, the phase represented by the running sum will overflow when it  crosses over 360o. 
 The fluctuation in the estimate necessi- tates that the mean threshold be set higher than the ideal, hence a loss. Doppler Filter Straddle Loss. This loss is due to a target not always being in the center of a doppler filter. 
 424 INTRODUCTION TO RADAR. SYSTEMS  with an applied voltage; the so-called serrasoid modulator 16 which generates a quadratic  waveform and compares this with a repetitive sawtooth wave to generate pulses that have a £2  variation in spacing which are filtered to form a linear-FM waveform; a tapped delay-line with  nonuniform tap spa~ings determined by the positive-going zero crossings of the desired linear­ FM waveform, followed by a filter to form the output waveform; a synthesizer 1 7 which  combines a staircase frequency waveform with the average desired slope, and a sawtooth  frequency waveform which fills-in the steps with a short linear FM; or by digital means in  which an algorithm performs a double integration to produce a phase at the output of the  generator which varies as the square of time, as required for a linear FM. 18 The digital  generator has the advantage of flexibility in the selection of bandwidth and time duration, as  well as good stability and low residual generation errors. 
 Since phase shift rather than time delay is used, as the frequency is changed, the direction of the null of the scanned beam is also changed, and the beam moves toward broadside with an increase in frequency. The amplitude at boresight of the difference-pattern output then increases linearly with a change in frequency. With a scan angle of 60° this change is from a null at the design frequency to a value of about -9 dB rel- ative to the sum pattern, at the edge of the band, where the band is defined by bandwidth (percent) = beamwidth (deg). 
 It is clear that the behavior is different and considerably more complex than that shown in Fig. 13.2 for the higher grazing angles and wider pulses. Trizna inter- prets these distributions as follows: in each trace, the left-hand segment (lowest cross section) is actually receiver noise, recorded when the radar footprint lay in shadow; the middle section corresponds to distributed clutter, for reasons relat- ing mainly to its weak dependence on resolution cell size; the right-hand section (highest cross section) describes the sea spikes, for reasons relating to the depen- dence on wind speed (similar to whitecap dependence) and the sheer size of the components (some individual absolute cross sections in excess of 1000 m2). 
 PRESSED AS THEY CAN OTHERWISE LEAD TO HIGH CROSS 
 P. E. Pace, D. 
 SCATTERING INFORMATION THAN #7 MEASUREMENTS MADE AT SINGLE FREQUENCIES 7HEN COHERENT 2#3 SCATTERING DATA ARE SUITABLY PROCESSED  IT IS POSSIBLE TO GENERATE  )3!2  IMAGERY  OR TWO 
 Inmany cases a simpler pulse generator can beused. When two ormore marker frequencies areneeded alternatively, the resonant circuit isswitched. Scaling-down israrely used, since more vacuum tubes would beinvolved and since itwould benecessary to recycle thecounting circuits oneach pulse cycle. 
 11.4 AMBIGUITY DIAC;RAM~,'~-'  The ambiguity diagram represents the response of the matched filter to the signal for which it  is matched as well as to doppler-frequency-shifted (mismatched) signals. Although it is seldom  used as a basis for practical radar system design, it provides an indication .of the limitations  and utility of particular classes of radar waveforms, and gives the radar designer general  guidelines for the selection of suitable waveforms for various applications.  The output of the matched filter was shown in Sec. 
 SQUARE RMS   SIDELOBE LEVEL IS OFTEN MORE IMPORTANT &OR EXAMPLE  IF  OF THE RADIATED POWER IS IN THE SIDELOBES  THE AVERAGE SIDELOBE LEVEL IS  
 There is no theoretical limit to the bandwidth of a Butler array except for the bandwidth  associated with the hardware making up the network, which can be greater thdn 30 percent.  They have even been constructed with bandwidths of several octaves." Operating over too  wide a band, however, changes the beamwidth, shifts the location of the beams, and can  introdiice grating lobes just as with any other array antenna.  The complexity of the Butler beamforming network increases with the number of ele-  ments. 
 }} }} JKRP   WHERE}NIS THE NORMAL TO THE SURFACE  }SIS THE OBSERVATION DIRECTION &IGURE     R IS  THE DISTANCE FROM THE FEED TO THE REFLECTING SURFACE   K   O K  IE  THE WAVENUMBER   AND THE E 
 (1.7)] these two roles were expressed by the trans­ mitting gain and the effective receiving aperture. The two parameters are proportional to one  another. An antenna with a large effective receiving aperture implies a large transmitting gain. 
 Curtis, “Design, performance, and applica - tions of a coherent random noise radar,” Optical Engineering , 37(6), pp. 1855–1869, June 1998. 27. 
   PP n  $ECEMBER   & 4 5LABY  2 + -OORE  AND ! + &UNG   -ICROWAVE 2EMOTE 3ENSING  !CTIVE AND 0ASSIVE    6OL )))  2EADING  -! !DDISON 
 6.13] HOMING 197 berofthe pair ofantennas inuse, and theradar echoes aredkplayed on anL-scope inwhich signals coIPing from theleftantenna cause adisplace- ment ofthe trace to~-ard the left, and signals from the right antenna displace the trace tothe right (Fig. 6“4). The range sweep islinear, upward from thebottom ofthescope, and the range isestimated byan engraved scale infron~ ofthetube. 
 MIZED BY BALANCING THE FEED TAPER AND THE FEED SPILLOVER AND MI NIMIZING OTHER LOSSES   BUT IS TYPICALLY n (OWEVER  DUAL REFLECTOR SYSTEMS EG  #ASSEGRAIN  HAVE AN ADDITIONAL DEGREE OF FREEDOM AND SURFACE SHAPING CAN BE APPLIED TO DECREASE THE TAPER LOSS AND ENABLE APERTURE EFFICIENCIES IN EXCESS OF    ! DIFFERENT TYPE OF DUAL REFLECTOR SYSTEM THAT IS PARTICULARLY  WELL 
 RESOLUTION IMAGING RADARS WITH REAL OR SYNTHETIC APERTURES PRO 
 22.3, operated at 1.275 GHz. The radar altimeter operated in the 12- to 14-GHz band and covered a 1.6-km swath directly below the spacecraft.TABLE 22.1 STS Rendezvous Radar Requirements* Search Acquisition Track Range Range rate Angle Angle rate± 30° spiral scan 12 nmi on O dBsm SW-I; 300 nmi on + 14 dBW transponder ± 1 percent 1 ft/s or 1 percent 8 mrad 0.14 mrad/s or 5 percent . The wind scatterometer operated at 14.599 GHz and covered two swaths, each 400 km wide and offset on each side of the spacecraft. 
 For more complete coverage, see the standard references.30,32 A simplified introduc - tion to the key parameters may be helpful.33 The natural starting point is the range equation, from which several properties  emerge that are unique to the spherical geometry of radars in orbit. In the narrow-beam  side-looking case, and neglecting the effects of Earth rotation, the radar-to-target range  variation generates a phase time-history over a synthetic aperture length of T seconds  from a point reflector at minimum slant range R0  Θ( )t R V Vt R= − +  4 202 0π λSC Beam  (18.5) where VBeam is the velocity on the surface of the illuminating footprint of the azimuth  antenna pattern. The time derivative of the phase yields the scatterer’s doppler history  f tV V RtD( )= −2 0 λSC Beam (18.6) in which the FM rate is proportional to the effective velocity V V VEff S C B eam =( )/1 2. 
 GROUND INTERFACE CAN CLEARLY BE SEEN COMING BACK TOWARD THE ANTENNA SYSTEM )N ADDITION  A WEAKER REFLECTION COMING FROM THE BURIED OBJECT IS STARTING TO FORM AND FOLLOWS THE AIR 
 C.: Radar Detection in Weibull Clutter, IEEE Trans., vol. A ES-12, pp. 736-743, Novem­ ber, 1976. 
 The Blass network required N2  couplers for N inputs and N outputs, while the conventional Fourier transform also requires  N2 computations for an N-point transform. The Butler network utilizes (N/2) log2 N junc­ tions, just as the FFT uses (N/2) log2 N computations for an N-point transform.  Within-pulse scanning.101-104 If an antenna beam is scanned sequentially through its angular  coverage, one position at a time, it illuminates all directions just as does a multiple-beam  array. 
 aircraft, or spacecraft. Other considerations include the size and weight, high-voltage  and X-ray protection. modulation requirements, and the method of cooling. 
 Special Receiving Techniques forAir-to-land Observation.— Some improvement inthe ability todistinguish land from water and atthesame time toseedetail inbuilt-up areas can beeffected byusing the anticlutter techniques described inSec. 12.8. Fast time constants, instantaneous automatic gain control, and other such circuits tend to suppress saturation onlong blocks ofsignals and tomake full use of changes inthesignal intensity. 
 Lewis, and L. Guthrie: Degradation Analysis of Pulse Doppler Ra- dars Due to Signal Processing, NAECON 1977 Rec., pp. 938-945. 
 Since any practical limiter has a  gradual transition into limiting, the limiter is often the largest contributor to receiver  channel nonlinearity in the linear operating region and can cause significant inter - modulation distortion of in-band signals. For this reason, the primary limiting stage is  usually located at the final IF stage where maximum filtering of out-of-band interfer - ence has been achieved. The lower operating frequency also allows implementation of  a limiter that more closely matches the ideal characteristics. 
 P.: Some Examples of Generalized Cassegrainian and Gregorian Antennas, IEEE Tru11s.,  vol. AP-12, pp. 685-691, November, 1964. 
 ART IN SMALL DEDICATED RADAR ALTIMETER MISSIONS )T INCLUDES A DUAL 
 148, 1416, 1417,14.21 forpictures ofsome commonly used 400-cycle motor-alternators. For heavy-current duty, particularly athigh altitude, brush wear becomes aproblem. Care should betaken tosee that allrotating devices using brushes requiring operation ataltitudes above 20,000 ft have suitable “high-altitude” brushes.1 Starting currents are often aserious problem inthe case ofmotor- alternator sets rated at750 vaormore since they may be5to10times lL.M.Robertson, “Effectof Altitude onElectric Ap~>aratus,'' Electrical Engineer- in~(June, 1945). 
 The waveguide switch unit is shown in more detail in ﬁgure 4.30. The layout of the operator controls was criticised by ASWDU. In a previous report on ASV Mk. 
 § ©¨¨¶ ¸··  PS S   WHERE 0# IS THE TOTAL CLUTTER POWER   RF IS THE STANDARD DEVIATION OF THE CLUTTER SPECTRAL  WIDTH  AND  FD IS THE AVERAGE DOPPLER SHIFT OF THE CLUTTER 4HE CORRESPONDING AUTOCOR 
 For dipoles with no ground plane the coupling  between elements does not decay so rapidly, and a 9-by-9 array appears reasonable.  For an array of open-ended waveguides, a 7-by-7 array should suffice. If accurate  prediction of the array performance is required, many more elements are needed  than are indicated above.47,48 It is often convenient to assume that the array is infinite in extent and has a uniform  amplitude distribution and a linear-phase taper from element to element. 
 In view of the familiarity of space wave propa - gation and the preceding discussion of skywave systems, it suffices here to address the  main features of HF surface wave (or ground wave) radar (HFSWR). HFSWR systems tend to fall into two categories: (i) low-power radars intended  primarily for oceanographic remote sensing, especially of ocean currents, and   (ii) larger and more powerful systems with target detection as their primary mission.  The former are in widespread operation around the world; only a few of the latter are  operational in surveillance roles. 
 11 J. Elliot. R. 
 Breit, G., and M. A. Tuve: A Test of the Existence of the Conducting Layer, Phys Rev., vol. 
 1962. 26.Thor.R.c.:ALargeTime-bandwidth Product Pulse-Compression Technique, IEEETrans.,vol. MIL-6.pp.169-173. 
 In spite of the assumptions, the infinite-array model has predicted with good  accuracy the array impedance and the impedance variations. Even arrays of mod - est proportions (less than 100 elements) have been in reasonable agreement with the  results predicted for an infinite array.49 Element Pattern.  From energy considerations, the directional gain of a perfectly  matched array with constant amplitude distribution ( h  = 1) will vary as the projected  aperture area from Eq. 
 STATE PERFORMANCE ENVELOPE WELL INTO THE REGION THAT HAD PREVIOUSLY BEEN DOMINATED BY ONLY VACUUM ELECTRONICS   )T IS NOT THE INTENT OF THIS  CHAPTER TO DELINEATE THE RELATIVE MERITS OF THESE SOMETIMES COMPETING TECHNOLOGIES  BUT RATHER TO DESCRIBE THE LIMITS  DESIGN PRACTICES  AND CHARACTERISTICS OF THE SOLID 
 TRONS WHEN USED IN OTHER APPLICATIONS ARE NOT FOUND IS THIS APPLICATION !LSO IMPORTANT IS THAT THE CIVIL MARINE RADAR BUSINESS IS VERY COMPETITIVE BECAUSE OF THE LARGE WORLD 
 Michelini, A.; Coppi, F.; Bicci, A.; Alli, G. SPARX, a MIMO Array for Ground-Based Radar Interferometry. Sensors 2019 ,19, 252. 
 Any use is subject to the Terms of Use as given at the website. Ground Echo.  GROUND ECHO  16.396x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 16 FIGURE   16. 33 Contributions to backscatter from a vegetation canopy  over a soil surface: (1) direct backscattering from plants, (2) direct backscat - tering from soil (includes two-way attenuation by canopy), and (3) plant-soil  multiple scattering ( after F . 
 15.16)  for V-polarization and the two-scale model  (in the form of Eq. 15.18) for H-polarization.   The wave spectrum used was the Phillips spectrum given in Eq. 
 ARRAYS WITHOUT NOISE NORMALIZATION AT THE OUTPUT OF SUB 
   PL PLN N=P  WHERE P  IS MEASURED FROM THE BROADSIDE DIRECTION .ORMALIZING  TO GET UNITY AMPLI 
 Intheremainder ofthissection, theantenna radiation patternwillbeexamined for variousaperture distributions usingEq.(7.10).Itwillbeassumed thatthephasedistribution acrosstheaperture isconstant andonlytheeffectsoftheamplitude distribution needbe considered. TheinverseFouriertransform givestheelectricfieldintensity whenthephaseandampli­ tudeofthedistribution acrosstheaperture areknown.Theaperture isdefinedastheprojec­ tionoftheantenna onaplaneperpendicular tothedirection ofpropagation. Itdoesnot matterwhether thedistribution isproduced byareflector antenna, alens,oranarray. 
 34. J. Blass, “The multidirectional antenna: A new approach to stacked beams,” in IRE Int. 
 Films taken by infra-  red light at night show that the bat’s radar system 1s so  sensitive that it can detect an echo-response from a tiny  insect flying past.  So close are we to world-shattering events and dis-  coveries that it is difficult for us to know if radar was  merely a development and a logical step forward in  science, All the fighting services paid glowing tribute  to the help radar gives in war. Now that we face sreater  . 
 C. Hansen (ed.),  New York: Academic Press, 1964, chap. 1. 
 Frisch, C. G. Little, D. 
 They sometimes have to be shut down and securely fastened  in strong gale winds. Even ir extreme winds are not encountered, a radome-enclosed antenna has  the advantage that it can be rotated with a much smaller motor than if it were outside the  radome exposed to even normal winds.  Solid reflector surfaces require more drive power in wind than do lattice or tubular  surfaces. 
 The tests did not give adequate opportunity toobserve theeffect ofthk interference inreducing themaximum range since the sites used were relatively isolated. The phase-shifted pulse method ofsynchronization (Sec. 17.6) gave results comparable tothose ofthe sine-cosine method with either type ofr-fequipment under reasonably interference-free conditions. 
 Clutter visibility factor. The signal-to·clutter ratio, after cancellation or doppler filtering, that  provides stated probabilities of detection and false alarm.  Clutter attenuation. 
 2/4(2 .OSTRADAMUS3TEEL 9ARD+OMSOMOLSK NA !MUR  4X ARRAY DESIGN  
 Thecross-correlation receiver ofFig.10.3testsforthepresence ofatargetat onlyasingletimedelayT,.Targets atothertimedelays,orranges,mightbefoundbyvarying T,.However, thisrequires alongersearchtime.Thesearchtimecanbereduced byadding OutputReceived signalh(t)- MixerLow-pass (multlplierlf- filterf------ (integrator) Stored Delay replicasltlr,.s(t-T,.l FiRU"e10.3Blockdiagram ofacross-correlation receiver.. parallel channels, each containing a delay line corresponding to a particular value of T,, as  well as a multiplier and low-pass filter. In some applications it may be possible to record the  signal on some storage medium, and at a higher playback speed perform the search sequen-  tially with different values of T,. 
 In order to counteract the mutual repulsion of the electrons which constitute the electron  beam, an axial magnetic field (not shown in Fig. 6.9) is generally employed. The magnetic field  focuses, or confines, the electrons to a relatively long, thin beam, and prevents the bc.:am from  dispersing. 
 The clutter residue spectrum contains more power at the lower modulation frequencies than Fig. 3.6, but the MTI residue is increased by only 1 dB. Long-range clutter is suppressed to nearly the same degree as short-range clutter. 
 IJ). Thus the lower microwave frequencies (bdow L band) are not usually strongly  affected by the evaporation duct. The upper frequency limit for ducting is determined by the  increased attenuation due to roughness of the sea and hy ahsorption of ekctromagne~ic energy  in the vicinity of the water vapor resonance at 22 GHz. 
 Out-of-plane data is often used in scatter jamming ( hot clutter ) calculations. The bistatic angle is calculated from the angles in Figure 23.9 by the use of  direction cosines:  b = cos−1 (cos qi cos qs − sin qi sin qs cos f) (23.17) Trends in this bistatic scattering coefficient database are summarized from Willis,1  Weiner,89 and Chapter 9 in Willis and Griffiths2 as follows: ● Most of the sB0 database is at X band, with 439 out of 650 data curves for both terrain  and sea clutter taken by 7 of the 9 organizations. The remaining database consists   of 172 data curves at L band (terrain only), 15 at S band (terrain only), 7 at C band (sea  only), and 17 at Ka band (terrain only), each provided by one organization. 
 Decorrelation in interferometric radar echoes. IEEE T rans. Geosci. 
 (8.25) can be  expressed as  The greater the gain of the antenna, the less the relative effect of the errors on the sidelobes.  Bv substituting the radiation intensity of Eq. (8.24) into the definition of gain (or directi-  vity) of Eq. 
 MULTIFUNCTIONAL RADAR SYSTEMS FOR FIGHTER AIRCRAFT  5.76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 5 An MFAR can support many activities (or modes) concurrently by interleaving  their respective data collections. Surveillance, track updates, and ground maps are  examples of such activities. The software needed to support each activity is mapped to  a specific client module, as shown in Figure 5.7. 
 A. Bakut and I. S. 
 Anelec- tron that goes through just asthe field between the grids ispassing1+300volts FIG. 11.22.—Schematic ofreflex klystron. H=heater K=cathode F=focusing electrode C=cavity R=reflector O=coaxial output line. 
 Record, vol. 3, pt. 8, pp. 
 Although thephaseofthestaloinfluences thephaseofthe transmitted signal,anystalophaseshiftiscanceled onreception because thestalothat generates thetransmitted signalalsoactsasthelocaloscillator inthereceiver. Thereference signalfromthecohoandtheIFechosignalarebothfedintoamixercalledtheplwsedetector. Thephasedetector differsfromthenormalamplitude detector sinceitsoutputisproportional tothephasedifference between thetwoinputsignals. 
 H.: Inactive Doppler Acquisition Systems, Trans. AIEE, vol. 81, pp. 
 NEERING SOLUTIONS THAT HAVE BEEN IMPLEMENTED TO MEET SPECIFIC MISSION OBJECTIVES  *INDALEE  3TAGE "*/2. 
   PP n  .OVEMBER   * "ROWN 0RIVATE COMMUNICATION    # * -ILLER  h-INIMIZING THE EFFECTS OF PHASE QUANTIZATION ERRORS IN AN ELECTRONICALLY SCANNED  ARRAY v IN  0ROC 3YMP %LECTRONICALLY 3CANNED !RRAY 4ECHNIQUES AND !PPLICATIONS   2!$# 
 Stillanother termsometimes employed inMTIradaristheintercllltter visibility. This describes theabilityofanMTIradartodetectmovingtargetswhichoccurintherelatively clearresolution cellsbetween patchesofstrongclutter.Clutterechopowerisnotuniform, so ifaradarhassufficient resolution itcanseetargetsintheclearareasbetween clutterpatches. Thehighertheradarresolution, thebettertheinterclutter visibility. 
 26.12  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 Because the evaporation duct is much weaker than the surface-based duct, its abil - ity to trap energy is highly dependent on frequency. Generally, the evaporation duct is  only strong enough to affect electromagnetic systems above 3000 MHz. For surface ducting conditions, the vertical extent of the duct is sufficient to allow for  its measurement using an ascending radiosonde, a descending rocketsonde, or a micro - wave refractometer onboard some sort of air vehicle. 
 It is very difficult to extend this to determine, in a repeatable and quanti - tative manner, the performance of the radar against point targets in predefined clutter  conditions. For this reason, some basic performance tests have necessarily been loosely  defined to allow scope for approved test laboratories to make their own qualitative judg - ments on basic radar performance, normally based on opportunistically testing the radar  over the sea and in precipitation in a variety of situations. Judgments on performance  can, therefore, be quite subjective and are naturally affected by the conditions actually  encountered during the tests. 
     
 The results will not be greatly dependent upon the  particular values of susceptance and conductance chosen. Similarly, the variation of the ob-  served quantities can be studied as a function of the load presented to the magnetron, with the  input parameters-magnetic field and current-likewise chosen for convenience. The plot of  the observed magnetron quantities as a function of the input circuit parameters;for some fixed  load, is called the perjbrmance chart. 
 The feeds might be used with a parabolic reflector, Cassegrain  antenna, or a lens. All four feeds generate the sum pattern. The difference pattern in one plane  is formed by taking the sum of two adjacent feeds and subtracting this from the sum of the  other two adjacent feeds. 
 The relative time delay is  positive for a target further in range than a reference target, and doppler frequency is   positive for an incoming target (negative range-rate). The complex envelope u(t)   is normalized to unit energy   | () |u t dt21 −∞∞ ∫= (8.49) The ambiguity function of u(t) is defined as the square magnitude of the autocorrelation  function  Ψu d u d f f( , ) | ( , ) | τ χ τ =2 (8.50) The ambiguity function is interpreted as a surface above the delay-doppler ( t – fd)  plane. The maximum value of the ambiguity function is unity at the origin ( t = fd = 0):  Ψ Ψu d u f( , ) ( , ) τ ≤ = 0 0 1 (8.51) The volume under the ambiguity surface is unity for any waveform u(t):   −∞∞ −∞∞ ∫ ∫= Ψu d d f d df ( , )τ τ 1 (8.52) In the general case, where the energy of the complex envelope is not normalized  to unity, the value of the ambiguity function at the origin is equal to ( 2E)2 where E  is the energy of the bandpass signal corresponding to u(t), and the volume under the  ambiguity function is also equal to ( 2E)2. 
 of Int.  Radar Symp ., IRS2005, Berlin (Germany), September 6–8, 2005, pp. 317–329. 
 (Thus it is similar to  the angle-error detector of a monopulse tracking radar.)  The ratio of the root mean-square noise voltage (z)112 to the slope M of the output  ,(AT,) evaluated at ATR = 0 will be taken as a measure of the rms error in time measure-  ' rnenl. or  where  The error is illustrated in Fig. 1 \.3. 
 155. B. L. 
 2013. The Round Earth.-The distance Rhtothe optical horizon, from anobserver situated hfeet above the surface ofaspherical earth ofdiameter Doftwould begiven bythe formula, Rh=V’DO.hifthe atmosphere didnot bend therays oflight. Actually, theearth’s atmos- phere decreases indensity with height, introducing adownward curvature inallrays, which allows aray toreach somewhat beyond the distance given bythe above formula. 
 VATION OF WEATHER BECAUSE A LOWER FREQUENCY WOULD PRODUCE A MUCH WEAKER RADAR ECHO SIGNAL FROM RAIN SINCE THE RADAR ECHO FROM RAIN VARIES AS THE FOURTH POWER OF THE FREQUENCY   AND A HIGHER FREQUENCY WOULD PRODUCE ATTENUATION OF THE SIGNAL AS IT PROPAGATES THROUGH THE RAIN AND WOULD NOT ALLOW AN ACCURATE MEASUREMENT OF RAINFALL RATE 4HERE ARE WEATHER RADARS AT HIGHER FREQUENCIES  BUT THESE ARE USUALLY OF SHORTER RANGE THAN .EXRAD AND MIGHT BE USED FOR A MORE SPECIFIC WEATHER RADAR APPLICATION THAN THE ACCURATE METEOROLOGICAL MEASUREMENTS PROVIDED BY .EXRAD # BAND  TO  '(Z   4HIS BAND LIES BETWEEN 3 AND 8 BANDS AND HAS PROPERTIES  IN BETWEEN THE TWO /FTEN  EITHER 3 OR 8 BAND MIGHT BE PREFERRED TO THE USE OF # BAND  ALTHOUGH THERE HAVE BEEN IMPORTANT APPLICATIONS IN THE PAST FOR # BAND.   !. ).42/$5#4)/. !.$ /6%26)%7 /& 2!$!2   £°£Ç 8 BAND  TO  '(Z   4HIS IS A RELATIVELY POPULAR RADAR BAND FOR MILITARY  APPLICATIONS )T IS WIDELY USED IN MILITARY AIRBORNE RADARS FOR PERFORMING THE ROLES OF  INTERCEPTOR  FIGHTER  AND ATTACK OF GROUND TARGETS   AS DISCUSSED IN #HAPTER  )T IS ALSO POPULAR FOR IMAGING RADARS BASED ON 3!2 AND )3!2 8 BAND IS A SUITABLE FREQUENCY FOR CIVIL MARINE RADARS  AIRBORNE WEATHER AVOIDANCE RADAR  AIRBORNE DOPPLER NAVIGATION RADARS  AND THE POLICE SPEED METER -ISSILE GUIDANCE SYSTEMS ARE SOMETIMES AT 8 BAND 2ADARS AT 8 BAND ARE GENERALLY OF A CONVENIENT SIZE AND ARE  THEREFORE  OF INTEREST FOR APPLICATIONS WHERE MOBILITY AND LIGHT WEIGHT ARE IMPORTANT AND VERY LONG RANGE IS NOT A MAJOR REQUIREMENT 4HE RELATIVELY  WIDE RANGE OF FREQUENCIES AVAILABLE AT 8 BAND AND  THE ABILITY TO OBTAIN NARROW BEAMWIDTHS WITH RELATIVELY SMALL ANTENNAS IN THIS BAND  ARE IMPORTANT CONSIDERATIONS FOR HIGH 
 It can be seen from Fig. 15.8 that the doppler frequencies for which the system is blind occur at multiples of the pulse repetition frequency. 75.3 CLUTTERCHARACTERISTICS Spectral Characteristics. 
 It is shown that it needs fewer samples and the bounded reconstruction error is smaller than the traditional CS. In the model of LS-CS-Residual, the information between different frames are used and there is also a debiasing step in the ﬁnal to reduce the bias caused by L1regularization. It can reconstruct the results much more accurately than CS. 
 IEE, vol. 133, pt. F, pp. 
 Then for the region 0,-, 0^ > - 2° and 0, + 0V < ~ 100°, y = - 20 dB matches the available vertically polarized data within about 5 dB for a 20-kn wind (« sea state 3 when fully developed). Below about 2°, pattern propagation factors and losses affect the measure- ments. Values for <JB of -50 dB ±5 dB have been measured.43 When the pattern propagation factors and losses are included in measurements, the data is some- times called effective a^0.114 For 0, + 6, > -100°, <JB° > O dB, reaching +10 dB in the specular-ridge region. 
 17.19 Eclipsing and straddle loss for M contiguous range gates and equal transmitted pulse and range-gate widths as a function of the number of receive gates and blanking width. Although Eq. (17.21) assumes contiguous range gates, the loss factor can be reduced by the use of overlapping gates at the expense of extra hardware and possibly more range ghosts. 
 Therefore, users and maritime authorities are gener - ally satisfied with the performance of linearly polarized systems in precipitation.Target DescriptionTarget  FeatureDetection Range in NM (for specified target size) Target TypeHeight Above  Sea Level  (meters) 9 GHz NM 3 GHz NM Shorelines Rising to 60 20 20 Distributed Shorelines Rising to 6  8  8 Shorelines Rising to 3  6  6 SOLAS ships † (> 5,000 gt) 10 11 11 Complex SOLAS ships † (> 500 gt)  5.0  8  8 Small vessel with radar  reflector meeting IMO  performance standards 4.0  5.0 (7.5 m2) 3.7 (0.5 m2)Point Small vessel of length 10 m  with no radar reflector 2.0  3.4 (2.5 m2) 3.0 (1.4 m2)Complex Typical navigation buoy  3.5  4.6 (5.0 m2) 3.0 (0.5 m2)Not specified, point  target assumed Navigation buoy with  corner reflector 3.5  4.9 (10 m2) 3. 6 (1.0 m2)Point Typical channel marker  1.0  2.0 (1.0 m2) 1.0 (0.1 m2)Not specified, point  target assumed † Ships conforming to the IMO Safety of Life at Sea (SOLAS9) regulationsTABLE 22.1  IMO Required Detection Performance in Clear Conditions ( Courtesy of IMO ) ch22.indd   4 12/17/07   3:02:30 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Updating Existing Tracks with Associated Detections.  The simplest method  of updating a track state is the a-b  filter41 described by  xs(k) = xp (k) + a [xm(k) − xp(k)] (7.19)  vs(k) = vs(k − 1) + b [xm(k) − xp(k)]/T (7.20)  xp(k + 1) = xs(k) + vs(k)T (7.21) where xs(k) is the filtered position, vs(k) is the filtered velocity, xp(k) is the predicted  position, xm(k) is the measured position, T is the time between detections, and ( a, b)  are the position and velocity gains, respectively. The selection of ( a, b) is a design  tradeoff. 
 TION THRESHOLD OF MORE THAN  D" 4HEN IF  .     IT IS DECIDED THAT 2'0/ IS NOT ACTIVE AND  NO ! 
 / 
 The propagation models within APM have also been combined with other envi - ronmental effects models, such as gaseous absorption and surface clutter, to form  a complete propagation package. The physical propagation phenomena considered   by APM version 2.0.01 are illustrated in Table 26.2. As can be seen from the table,  ch26.indd   16 12/15/07   4:53:29 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 623–632, 1963. 84. J. 
 QUENCY F S  OR ANY INTEGER MULTIPLE .FS  )N CONVENTIONAL BASEBAND APPROACHES  SAM 
 DOPPLER CELL OF THE DOPPLER PROCESSOR FOR A SINGLE COHER 
 The disturbance limiting the accuracy of the radar measurement is assumed to be the  receiver noise. It is furthermore assumed that bias errors have been removed.  It will be shown that the rms error i5M of a radar measurement M can be expressed as  kM i5M = ---= fiE/N 0 (11.1)  where E is the received signal energy. 
 BACK VALUES EMPLOYED ARE SEVERAL OF THOSE USED FOR THE UNSTAGGERED VELOCITY RESPONSE PLOT IN &IGURE  )F SCAN 
 PERIOD FEATURES IN LOW 
 The odd-numbered sidelobes are  therefore out of phase with the main lobe, and the even-numbered ones are in phase. Also  shown in Fig. 7.3 is the radiation pattern for the cosine aperture distribution. 
 §S PULSEWIDTH.   05,3% #/-02%33)/. 2!$!2   n°Ç &REQUENCY $OMAIN 7EIGHTING FOR ,&- 4IME 3IDELOBE 2EDUCTION    ! FREQUENCY  DOMAIN WEIGHTING FILTER IS USED FOLLOWING THE MATCHED FILTER FOR TIME SIDELOBE REDUCTION  4AYLOR WEIGHTING PROVIDES A REALIZABLE APPROXIMATION TO THE IDEAL $OLPH 
 There is no continuous range indication,  but the three marker beacons are placed to indicate the  start of the descent, the approach end of usable runway  —and one also acts as a central checking-point. With the  glide-path ground transmitter and associated equipment  this is a comparatively costly outfit to work, but in  practice the aircraft can be localized to within 0-75°,  and the glide-path checked to within 0-3° above or  below. There are no language difficulties with SCS-51,  for the pilot has to get no instructions from the ground. 
 109. Sensors 2019 ,19, 3344 Figure 4. Flow chart of asteroid’s ISAR signal modelling. 
 CAUSED ANGLE ERRORS  ARE  GREATER THAN THE WANDER OF THE TARGET CENTER OF GRAVITY AND CAN FALL OUTSIDE THE TARGET SPAN  &IGURE  SHOWS TYPICAL SAMPLES OF SPECTRAL 
 The sum signal at the IF output also provides a reference signal to phase detectors  that derive angle-tracking-error voltages from the difference signals. The phase detec - tors are essentially dot-product devices producing the output voltage  e e = =| || | | || | | |Σ ∆ Σ ∆∆ Σcos or cos θ θ (9.1) where e =  angle-error-detector output voltage  Σ = magnitude of sum signal  ∆ =  magnitude of difference signal  q =  phase angle between sum and difference signals The dot-product error detector is only one of a wide variety of monopulse angle-error  detectors described in Chapter 7 of Sherman.1 Normally, q is either 0 ° or 180 ° when the radar is properly adjusted, and the only  purpose of the phase-sensitive characteristic is to provide a plus or minus polarity cor - responding to q = 0° and q = 180°, respectively, giving a + or – polarity to the angle- error-detector output to indicate to the servo which direction to drive the pedestal. In a pulsed tracking radar, the angle-error-detector output is bipolar video; that  is, it is a video pulse with an amplitude proportional to the angle error and whose  polarity (positive or negative) corresponds to the direction of the error. 
 W.P.:AnRFMultiple Beam-Forming Technique, IRETI'(//IS.,vol.MIL-6. pp.179-186. April.i'j62. 
 IIIB, described below. 3.5.1 ASV Mk. IIIB The modi ﬁcations introduced for ASV Mk. 
 This is not an easy task since the angles of arrival of the direct and  scattered signals are generally close to one another when the bistalic radar is arrnnged to  provide fence coverage.  Bistatic Radar equation. The simple form of the radar equation for monostatic radar is given  by the familiar expression  P,G2 l2am  (4n)3R4L;L, monostatic (14.35) . 
 Quite arbitrarily, wetake “nearly all” tomean atleast 10percent ofthetime—a large percentage incom- parison with that usual. inpulsed radar, where energy isgenerally emitted during less than 0.1per cent ofthe time. InFourier terms this may mean, inthe case offrequency modulation, almost any bandwidth but phases such astogive constant amplitude. 
 Barton, Radar Systems Analysis and Modeling , Norwood, MA: Artech House, 2004. ch17.indd   35 12/17/07   6:50:14 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 One effect of refraction is to extend the distance to the horizon, thus increasing  PROPi\(iATION OFRAUAR WAVES447 a5°.~.I'Frpe-spacecoverage contour-7 /I' I ',,~,1. 300 /~f'10° II1 / I 'iII.}/I ;/1j I,j,Ii/ I / t~ { /1 .l,~l-d'_i )I' I Range,nm, (b)verticalpolarization Figure12.4(COII/i/lllecl) earth,Lohing. however. 
 Domville, “The bistatic reflection from land and sea of X-band radio waves, Part II,” GEC  (Electronics) Ltd., Stanmore, England, Memorandum SLM2116, July 1968.  96. A. 
 &- WAVEFORM WILL HAVE A THUMBTACK 
 AUTOMATIC DETECTION, TRACKING, AND SENSOR INTEGRATION  7 .76x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 7 where  a = 1.386/(beamwidth)2 (7.8) and A1 and A2 are the two largest amplitudes of the returned samples and occur at  angles q1 and q2 = q1 + ∆q, respectively. Because the estimate should lie between q1  and q2 and Eq. 7.7 will not always yield such an estimate, ˆθ should be set equal to q1  ifˆθ< q1 and ˆθ should be equal to q2 if ˆθ > q2. 
 9.25 aminimum amount (about I@in.inthefinal installation), thus present- ing aminimum offrontal area. These factors make this installation aerodynamically superior tothose shown inFig. 9“41 and 938. 
 J.: Matched Filter for Frequency-Modulated Continuous-Wave Radar Systems, Proc.  IEE (London}. vol. 
 An example of the use of phase difference in discriminating surface classes in  the Amazon basin is illustrated in Figure 16.47.179 Note the significant differences  between C and X band for Macrophyte and Flooded forest. These differences could  be used as discriminators to identify these classes, but normally they would simply be  additional elements in the state vectors used in statistical algorithms. 16.9 SCATTERING COEFFICIENT   DATA NEAR GRAZING Conditions for backscatter near grazing incidence are sufficiently different from those at  steeper incidence that they must be described separately. 
 ln an electronically scanned array the antenna  elements, the transmitters, the receivers, and the data-processing portions of the radar are  often designed as a unit. A given radar might work equally well with a mechanically positioned  array, a lens, or a reflector antenna if they each had the same radiation pattern, but such a  radar could not be converted efficiently to an electronically scanned array by simple replace­ ment of the antenna alone because of the interdependence of the array and the other  portions of the radar.  Radiation pattern. 
 2011 ,32, 3565–3588. [ CrossRef ] 24. Samsonov, S.; d’Oreye, N.; Smets, B. 
 136. Ref. 37, vol. 
 Thelensisusuallylessefficientthancomparable reflector antennas becauseoflosswhen propagating through thelensmedium andthereflections fromthetwolenssurfaces. Ina zonedlenstherewillbeadditional, undesired scattering fromthesteps.Although itisdanger­ oustogeneralize, theadditional lossesfromthesourcesinasteppedlensmightbe1or2dB.72 Thelackofsuitablesolidorartificial dielectric materials haslimitedthede.yelopment of lenses.Theproblem ofdissipating heatfromlargedielectric lensescansometimes restricttheir usetomoderate-power ortoreceiverapplications. Conventional lensesareusuallylargeand heavy,unlesszoned.Toreducethelosscausedbyscattering fromthesiepsinazonedlens, theratioofthefocallengthItotheantenna diameter Dmustbemadelarge(oftheorderof unity).Lenseswhichmustscanbyposidoning thefeedshouldalsohavelargellD ratio.Alarge liDrequires agreatermechanical structure becausethefeedsarebiggerandmustbesupported fartherfromthelens.Themechanical supportofalensisusuallymoreofaproblem thanwith areflector. 
 CODED WAVEFORMS  AND TIME 
 Sensors 2019 ,19, 1529 to Equation (11). The radar parameters were set in reference to the ERS-2 SAR parameters listed in Table 4. The size of the current ﬁeld is 24 km ×24 km, and the spatial resolution is 100 m ×100 m. 
 That istosay, themaximum range obtainable isinversely proportional tothe square root ofthe height ofthe aircraft, keeping everything about the radar set constant but the vertical radiation pattern ofthe antenna, which weassume tobeadjusted tooptimum shape foreach height. Aproblem related tothepreceding one ismet inthedesign ofground- based air-search radar, which may berequired toprovide uniform cover- age atallranges for point targets (aircraft) flying atsome limiting altitude h. Here, however, uisgenerally assumed tobeconstant: the reader will easily verify that this assumption leads again tothe require- ment that thegain vary asCSC2 0,but with adiflerent final result forthe dependence ofSupon h,R,and a. 
 BEAM LINEAR 
 I and II, Microwave J ., vol. 15, no. 9, pp. 
 The .wc~rc,/~ ~triil tlt.trction function requires that the conlputer generate the angular coor-  d~nates of the region to be searched, the type of transmitted waveform to be used, the length of  the dwell period, and the time assigned for the execution of the dwell by the radar. Since tht:  radar is performing tracking and other functions as well as search, conflicts in scheduling the  radar or the processor might arise. Tracking functions are often more critical of time than  search, and would have a higher priority in the event of a scheduling conflict. 
  
 PER 
 THRESHOLD (T) FIG. 8.4 Single-sweep false-alarm probability Pfa versus threshold for moving window. The noise is Rayleigh-distributed with cr = 1. 
 '(Z CLOUD RADAR SYSTEM ON  A .!3! HIGH 
 The detected video output from the receiver was fed to the indicator unit. 4.2.5 Attenuator, type 53 The attenuator divided the transmitter power between the scanner and a dummy load, in such a way as to present a constant impedance to the transmitter. The SWR was maintained at better than 1.1:1, so that the transmitter was not pulled in frequency by more than 1 Mc/s. 
 When a large  number of pulses are integrated (small signal-to-noise ratio per pulse), the difference between  postdetection and predetection integration is more pronounced.  The dashed straight line applies to an integration-improvement factor proportional to  nli2. As discussed in Sec. 
  3UPER (ORNET SETS A NEW STANDARD AS IT DELIVERS  MULTIPLE *$!-S SIMULTANEOUSLY ON TARGET v -ARKET7ATCH  $ECEMBER     - 3ELINGER  h53 .AVY EYES @GROWTH PLAN FOR 3UPER (ORNETS !%3! RADAR v  !EROSPACE $AILY  AND $EFENSE 2EPORT  $ECEMBER     2 % (UDSON  3 / !+3  0 0 "OGDANOVIC  AND $ $ ,YNCH  h-ETHOD AND 3YSTEM FOR  2EDUCING 0HASE %RROR IN A 0HASED !RRAY 2ADAR "EAM 3TEERING #ONTROLLER  53 0ATENT        2 (ILL  $ +RAMER  AND 2 -ANKINO  h4ARGET $ETECTION 3YSTEM IN A 2ADAR 3YSTEM %MPLOYING  -AIN AND 'UARD #HANNEL !NTENNAS v 53 0ATENT     2 -ONZINGO AND 4 -ILLER   )NTRODUCTION TO !DAPTIVE !RRAYS   .EW 9ORK *OHN 7ILEY  3ONS     PP n  2 +LEMM  h!DAPTIVE AIRBORNE -4) !N AUXILIARY CHANNEL APPROACH v  )%% 0ROCEEDINGS  VOL    PART &  NO   P     3 !KS  $ $ ,YNCH  * / 0EARSON  AND 4 +ENNEDY  h!DVANCED MODERN RADAR v %VOLVING  4ECHNOLOGY )NSTITUTE 3HORT #OURSE .OTES  .OVEMBER   7ORK PERFORMED BY , 'RIFFITHS AND # 4SENG  h!DAPTIVE ARRAY   RADAR PROJECT REVIEW v (UGHES  !IRCRAFT )2$  PERFORMED AT 53#  *ULY     # +O  h! FAST ADAPTIVE NULL 
 R. Edison, R. K. 
 V., 20, 21  ASV, 136  BABS, 158 et seq.  Baird, J. L., his British patent,  8 I  Bat, radar system of, 17  Bedford, L. 
  
 Detection is somewhat easier than with sky-wave propagation since iono­ spheric e~ects are not present and clutter returns from aurora generally can b~Jeliminated by  time gating. The ground-wave radar has a far shorter range than can be obtained via sky waw  because of the propagation loss which increases exponentially with range. A ground-wave  radar of a size and frequency comparable to the sky-wave radar discussed in the abovc might  have a range against low-altitude aircraft targets of perhaps 200 to 400 km. 
 153. Cheng, D. H. 
 Due to their enormous mass and relatively simple structure, pulsars are exceptionally stable rotators whose timing stability rivals that of conventional atomic clocks. It is the reason pulsar emissions to be used for spacecrafts radio navigation, asteroids detection, and imaging [ 2]. A navigation system based on celestial sources will be an independent positioning system and available in any Earth orbit as well as in interplanetary and interstellar space [ 3–5]. 
 RESPONDING DECREASE IN ITS COST  HAS HAD A PROFOUND IMPACT ON THE WAY RADAR SYSTEMS ARE DESIGNED -ORE AND MORE FUNCTIONS THAT HISTORICALLY WERE IMPLEMENTED IN ANALOG HARDWARE ARE NOW BEING PERFORMED DIGITALLY  RESULTING IN INCREASED PERFORMANCE AND FLEXIBILITY AND REDUCED SIZE AND COST !DVANCES IN ANALOG 
 The special demands of  MTI (moving target indication), pulse doppler, CW radar, phased-array radar, EMC  190 . RADAR TRANSMITTERS 191  (electromagnetic compatibility), and ECCM (electronic counter-countermeasures) all  influence the type or transmitter selected and its method of operation. The choice of transmit­ ter also depends on whether the radar operates from fixed land sites, mobile land vehicles,  ships. 
 (ed.): Special Issue on Adaptive Antennas, I EEE Trans., vol. AP-24, September, 1976.  152. 
 Ward: "Handbook of Radar Measurement," Prentice-Hall, Inc., N.J. 1969.  8. 
 SECTIONAL AREA PER  UNIT VOLUME AND  6  IS THE VOLUME SAMPLED BY THE RADAR G CAN ITSELF BE WRITTEN AS   HS   £I I.     WHERE . IS THE NUMBER OF SCATTERERS PER UNIT VOLUME AND  RI IS THE BACKSCATTERING CROSS  SECTION OF THE  ITH POINT SCATTERER )N GENERAL  THE METEOROLOGICAL SCATTERERS CAN TAKE ON  A VARIETY OF FORMS  WHICH INCLUDE WATER DROPLETS  ICE CRYSTALS  HAIL  SNOW  AND MIXTURES  OF THE ABOVE -IE DEVELOPED A GENERAL THEORY FOR THE ENERGY BACKSCATTERED BY AN OPTICAL PLANE  WAVE IMPINGING ON CONDUCTING SPHERES IN COLLOIDAL SUSPENSION 4HE SAME THEORY APPLIES TO SPHERICAL RAINDROPS FALLING THROUGH THE ATMOSPHERE FOR WHICH THE BACKSCATTERED ENERGY IS A FUNCTION OF THE WAVELENGTH  K  OF THE INCIDENT ENERGY AND THE RADIUS  A  AND COMPLEX  INDEX OF REFRACTION  M  OF THE PARTICLE 4HE RATIO  OAK DETERMINES THE DOMINANT SCATTER 
 For example, assume  the event in question to be the output voltage v from a radar receiver. Upon obtaining this  voltage, it is of interest to determine whether the output was caused by noise or by signal in the  presence of noise. The probabilities of obtaining noise and signal-plus-noise before the event  takes place are the a priori probabilities. 
 8.4h). The adjacent elements are connected by a phase shifter with phase shift 4. All  the phase shifters are identical and introduce the same amount of phase shift, which is less than  ZT~ radians. 
 LOADING  RESULTS IN A VERY LIGHTWEIGHT STRUCTURE 4HIS SAVES COSTS IN THE ANTENNA TURNING GEAR AND MAKES THE INSTALLATION EASIER !N EXAMPLE OF THIS TYPE OF ANTENNA  PRODUCED BY +ELVIN (UGHES  IS ILLUSTRATED IN &IGURE  3MALL CRAFT RADARS HAVE USED PRINTED ARRAYS FOR SOME YEARS  AS WELL AS SLOTTED  WAVEGUIDE ARRAYS 3MALL  HORN 
 446–451. 17. N. 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.476x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 3. A third, more drastic approach, consists of discarding the measurement with higher  range among the two measurements that have exceeded the detection threshold of  more than 3 dB. 
 Reconstructed aspect dependent scattering of pixel P via the three methods. 4.2. Gotcha Volumetric SAR DAT A Gotcha volumetric SAR dataset [ 22] is X-band circular SAR data that consists of CSAR phase history data collected at the X-band with a 640-MHz bandwidth. 
 Withanoperator makingaheightmeasurement manually, from 2to4measurements perminutemightbemade.Inonenodding-beam heightfinder,upto22 target-heights perminutecanbeobtained whentheslewing iscontrolled automatically for maximum dataratebythecomputer oftheassociated data-handling system.29Theabsolut~ heightaccuracy ofanodding-beam heightfindercanbe±1500ft(460m)at150nmi(280km) range. Thenodding-beam heightfinderisoneoftheoldesttechniques formeasuring theeleva­ tionangleofaircrafttargets.Itisalsooneofthebest.Itsaccuracy isprobably asgoodorbetter thanany?thertechnique. Eventhoughaseparate radarisemployed tomeasure}arget height, thecombined costofthe20air-surveillance rada'randthenodding-beam heightfindercanbe lessthanthecostofacomparable single3Dradar.(Itisnotalwaystruethattworadarscost more,aremorecomplex, oroccupymorevolumethana"single" radardesigned todothe samejob.)Another advantage oftheseparate nodding-beam heightfinderinmilitary applica­ tionsisthatitgenerally operates atahigherfrequency (SorCbandsarecommon choic~s) thandoesthe20air-surveillance radar.Thisincreases theECCMcapability ofthesystem sinceajammermustradiateinbothradarbandssimultaneously todenythelocation ofair­ crafttargets.Theuseofahigherfrequency fortheheightfinderisappropriate sinceitcanbeof shorterrangethanthe2Dair~surveillance radar,andtheantenna aperture canb~ofsmaller sizeforagivenbeamwidth. 
 VARYING  AMPLITUDE AMPLI 
 PULSE CAPABILITY BY LOWERING THE DISSIPATED POWER IN THE TRANSISTOR  PERHAPS BY REDUCING THE OPERATING VOLTAGE AND POWER OUTPUT  IS ONE METHOD OF ACHIEVING THE DESIRED RELIABILITY !NOTHER METHOD MAY INVOLVE THE REDUCTION IN AMBIENT TEMPERATURE WITH THE USE OF CHILLED FLUID IN THE AMPLIFIER HEAT 
 Uchebn. Zaved., Radiofiz., vol. 28, pp. 
 [ CrossRef ][PubMed ] ©2020 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http: //creativecommons.org /licenses/by/4.0/). 
 As the means for choosing a and /? become more sophisticated, the optimal a-fl  tracker becomes equivalent to a Kalman filter even for a target trajectory model with error. In  this sense, the optimal a-/3 tracking filter is one in which the values of a and /? require  knowledge of the statistics of the measurement errors and the prediction errors, and in which a  and /3 are determined in a recursive manner in that they depend on previous estimates of the  mean square error in the smoothed position and vel~city.'~  (The above discussion has been in terms of a sampled-data system tracking targets  detected by a surveillance radar. The concept of the a-/? tracker or the Kalman filter also can  TRACKING RADAR185 position andvelocity, assuming smallvelocitychanges between observations, ordatasamples. 
 88-93, 1980. 14. Multistatic Mode Raises Radar Accuracy, Aviat. 
 The image that r-esults by illuminating the film is focused on a tilted  plane since the curvature of the wavefront is proportional to the range. (This is somewhat like  an optical analog of the radar itself.) Since it is undesirable to operate with the image focused . 524 INTRODUCTION TO RADAR SYSTEMS  (a)  (b)  figure 14.4 (a) Synthetic aperture radar image of San Diego, California obtained with the X -band GEMS  (Goodyear Electronic Mapping System) radar. 
  
 TRACTING  D" 5NEQUAL SIDEBAND POWER CAN ONLY RESULT FROM ADDITIVE SIGNALS OR NOISE OR CORRELATED AMPLITUDE AND PHASE NOISE COMPONENTS !MPLITUDE MODULATION !-  OF THE 34!,/ IS TYPICALLY NOT A SIGNIFICANT FACTOR AS  IT IS USUALLY AT A LOWER LEVEL THAN THE PHASE NOISE AT SMALL OFFSET FREQUENCIES FROM CAR 
     AND WE DEFINE THE RADAR REFLECTIVITY FACTOR : AS  :$I I.    £     )N RADAR METEOROLOGY  IT IS COMMON TO USE THE DIMENSIONS OF MILLIMETERS FOR DROP  DIAMETER  $I AND TO CONSIDER THE SUMMATION TO TAKE PLACE OVER A UNIT VOLUME OF SIZE    M TO YIELD A VOLUME DENSITY EXPRESSION 4HEREFORE  THE CONVENTIONAL UNIT OF  : IS  IN MMM &OR ICE PARTICLES   $I IS SOMETIMES EXPRESSED AS THE DIAMETER OF THE WATER  DROPLET THAT WOULD RESULT IF THE ICE PARTICLE WERE TO MELT COMPLETELY (OWEVER  THE RADAR  SCATTERING PROCESS FOR THE MANY SHAPES AND TEMPERATURES OF ICE PARTICLES IS EXTREMELY COMPLICATED AND A DEFINITIVE GENERALIZED EXPRESSION CANNOT BE GIVEN )T IS OFTEN CONVENIENT TO TREAT THE DROP OR PARTICLE SIZE DISTRIBUTION AS A CONTINUOUS  FUNCTION WITH A NUMBER DENSITY  .$   WHERE  .$  IS THE NUMBER OF DROPS PER UNIT  VOLUME HAVING DIAMETERS BETWEEN  $ AND $   D$ )N THIS CASE   : IS GIVEN BY THE SIXTH  MOMENT OF THE PARTICLE SIZE DISTRIBUTION    :N $ $ D $ c¯      )F THE RADAR BEAM IS FILLED WITH SCATTERERS  THE SAMPLE VOLUME OF  6 IS GIVEN   APPROXIMATELY BY   6RCyPQF T     WHERE P  AND E ARE THE AZIMUTH AND ELEVATION BEAMWIDTHS   C IS THE VELOCITY OF LIGHT  AND  S IS THE RADAR PULSE WIDTH 3UBSTITUTING %QS  AND  INTO %Q   WE SEE THAT THE  2#3 FOR THE DISTRIBUTED WEATHER SCATTERER IS DIRECTLY PROPORTIONAL TO THE PULSE VOLUME  AS DETERMINED BY THE PULSE LENGTH AND ANTENNA BEAM AT THE TARGET RANGE 4HEN  COMBINING %QS     AND  AND SUBSTITUTING INTO %Q  GIVES.   -%4%/2/,/')#!, 2!$!2   £°x  0RRC+$ C+RI I. 
 A TRMM follow-on program, the Global Precipitation  Measurement (GPM) program, envisions extending precipitation coverage to the  mid-latitude (65 ° N and S latitude) flying in a 250 km altitude orbit and using dual  wavelength precipitation radar (DPR)180 at Ku and Ka bands for more accurate rainfall  estimates using attenuation techniques.181,182 The two radars will have matched beams  from two slotted waveguide array antennas and provide coverage under the spacecraft  track similar to TRMM. CloudSat is a satellite launched in 2006 flying a W band (3 mm) cloud profiling  radar (CPR) orbiting the Earth in a sun synchronous orbit at an altitude of about   700 km.183 The transmitter is an Extended Interaction Klystron (EIK) high-power  amplifier generating a 3.3 msec monochromatic pulse having peak power of 1.7 kW.  The antenna is a 1.85 m diameter reflector offset fed by a quasi-optical transmission  line and produces a 0.12 ° beam with extremely low sidelobes. 
 pp. 89-106, August, 1964.  41. 
 With pulse-to-pulse staggering, good response can be obtained on all dopplers of interest on each scan. In addition, better velocity response can be obtained at some dopplers thanOPTIMUM CLUTTERDOPPLER-SHIFT VARIATIONSAVERAGE SCR IMPROVEMENT ISCR (dB) . CHAPTER 16 AIRBORNE MTI Fred M. 
 BLANKING SYSTEM AFTER , -AISEL Ú )%%%   .   %,%#42/.)# #/5.4%2 
 SECTION MEASURE 
 From the rear half of the cone-sphere, the radar cross section is approximately that of the  sphere.  The nose-on cross section of the cone-sphere varies, but its maximum value is approxi­ mately 0.412 and its minimum is 0.0U.2 for a wide range of half-angles for frequencies above  the Rayleigh region. The null spacing is also relatively insensitive to the cone half-angle. 
 (4.1) because thermal noise sets a definite limit on receiver sensitivity, and this simplified range equation merely assumes that the receiver is always made as sensitive as possible. Since average transmitter power is only one of the factors in the range equa- tion and is so costly, why does power usually end up being so high? Wouldn't it be better to use less power and to make up for it with more aperture or more scan time? The flaw in this argument is that increasing the antenna aperture increases its cost quickly because its weight, structural complexity, dimensional tolerance problems, and pedestal requirements grow rapidly with antenna size. The only other factor, scan time, is usually set by some definite system operational requirement: to look at all aircraft within 100 mi every 4 s, for example, to permit prompt recognition of changes in aircraft direction of travel; so scan time is usu- ally not flexible (which probably explains why everyone talks about the "power- aperture product" of a radar rather than its "power-aperture-scan-time product"). 
 ING BY BEING IN A TIME SEQUENCE 4HIS WAS PERFORMED BY A CONTINUOUS CONICAL BEAM SCAN  AS ILLUSTRATED IN &IGURE   OR BY SEQUENTIALLY LOBING UPDOWN AND RIGHTLEFT  AND OBSERVING THE DIFFERENCE BETWEEN  AMPLITUDES AS A MEASURE OF  DISPLACEMENT OF THE  ANTENNA AXIS FROM THE TARGET 4HE SIGNAL OUTPUT FOR A CONICAL 
 24 INTRODUCTION TO RADAR SYSTEMS  may be considered envelope detectors. Either a square-law or a linear detector may be  assumed since the effect on the detection probability by assuming one instead of the other is  usually small.  The noise entering the IF filter (the terms filter and amplifier are used interchangeably) is  assumed to be gaussian, with probability-density function given by  (2.20)  where p(v) dv is the probability of finding the noise voltage v between the values of v and  v + dv, ,j10 is the variance, or mean-square value of the noise voltage, and the mean value of 11 is  taken to be zero. 
 At the low grazing angles encountered in  maritime radar operations, sea clutter becomes spiky and intermittent, requiring spe - cial attention to signal processing and the interpretation of the radar signal. Moreover,  features of the sea environment such as rain, currents, slicks, and refractive anomalies  can confuse the reliable separation of target returns from clutter artifacts. The question of microwave sea clutter theory remains unsettled. 
 WATER CONTENT OF THE  UPPER LAYER OF SNOW  SO SCATTER IS MUCH LOWER FROM THE WET DAYTIME SNOW WHERE SOLAR MELTING HAS COM 
 Ship classiﬁcation based on superstructure scattering features in SAR images. IEEE Geosci. Remote Sens. 
 The  changes can have a profound effect on radar performance. The individual resolved spikes can  cause false alarms. Raising the receiver threshold level to reduce the false alarms can result  in a significant loss in sensitivity to desired targets. 
 The  frequency error will be like that of Eq. (1 1.20) but with the roles of B and T reversed.  The rms error in the measurement of doppler frequency with a trapezoidal pulse is  Sf = (2T2/3 + 2T1)'"  TITI Ti 2T3 'I2 2E 'I2 trapezoidal pulse (1 1.3 1) 2n(F + -  3 +-+-) 15 3 (%)  This reduces to the expression for a rectangular pulse [Eq. 
 The filter in the AGC loop should  pass all frequencies from direct current to just below the conical-scan-modulation frequency.  The loop gain of the AGC filter measured at the conical-scan frequency should be low so that  the error signal will not be affected by AGC action. (If the AGC responds to the conical-scan  frequency, the error signal might be lost.) The phase shift of this filter must be small if its phase  characteristic is not to influence the error signal. 
 VALUE PROBLEM '"60  IN WHICH THE SEA AS A WHOLE IS CONSIDERED A BOUNDARY SURFACE WHOSE CORRUGATIONS ARE DESCRIBED BY SOME KIND  OF STATISTICAL PRO 
 Finally, DBS imaging is performed. The number of newly merged pulses in the proposed KA-DBS algorithm is twice larger than that in the conventional DBS algorithm with the same dwell time. Therefore, the cross-range resolution is improved by a factor of two in KA-DBS. 
 At this point a high mismatch was observed. The mismatch improved as the grating lobe moved further into real space. The combination of waveguide simulators and small arrays provides powerful empirical tools to supplement the analytical techniques. 
 In the case of an antenna placed on an interface, the two most important parameters  are the current distribution and the radiation pattern. At the interface, currents on the  antenna propagate at a velocity, which is intermediate between that in free space and  that in the dielectric. In general, the velocity is retarded by the ( ) / εr+1 2 . 
 In this chapter, the simple radar equation will be extended to include most of the impor-  tant factors that influence radar range performance. If all those factors affecting radar range  were known, it. would be possible, in principle, to make an accuratc prediction of radar  perforpance. 
 pp. 65 69. March. 
 Sheen, D.M.; McMarkin, D.L.; Hall, T.E. Near-ﬁeld three-dimensional radar imaging techniques and applications. Appl. 
 It should properly be  508INTRODUCTION TORADAR SYSTEMS 13.9ANGEL ECHOES Radarechoescanbeobtained fromregionsoftheatmosphere wherenoapparent rdkcting sourcesseemtoexist.Thesehavebeencalledbyvariousnames,buttheyarecommonly called O'lOstsoraI/gels.Theycantakeseveraldifferent formsandhavebeenattributed tovarious causes.Therearetwogeneralclassesofangelechoes:dotangels,whicharepointtargetsdueto birdsandinsects,anddistrihuted angels,whichhavesubstantial horizontal orvaticalextent andareduetoinhomogeneities oftherefractive indexoftheatmosphere. Birdsandinsectsin substantial number canalsoappearasdistributed angels,andcanhaveadegrading effedon radar.SincetheyaremovingcluttertoanMTIradartheyaredifficulttoremovebydoppler filtering. Sensitivity timecontrol(STC)hasprovenasatisfactory method, inmanycases,for reducing theeffectofsuchclutter.Operation atUHFcanreducethebackscatter frominsects and,tosomeextent,birdsbecauseofthefourth-power relationship between crotssectionand frequency ofascatterer intheRayleigh region(Eq.13.17).Inhomogeneities oftheatmospheric indexofrefraction generally donotproduce strongenoughbackscatter tobeaseriollssource ofcluttertomostradars. 
 A convenient set of units for this equation is  V kf fkBr(knots GHz)., , ,... = ⋅⋅= ±0 290 1 2 (2.2) where fr is the PRF (pulse repetition frequency) in hertz; and fGHz is the transmitted  frequency, in gigahertz. Note from the velocity response curve that the response to  targets at velocities midway between the blind speeds is greater than the response for  a normal receiver. 
 DOPPLER RADAR OBSERVATIONS OF CONVECTIVE STORM CIRCULATIONS v IN  TH  #ONF 2ADAR -ETEOROL  !-3  "OSTON    PP n  $ * -C,AUGHLIN  6 #HANDRASEKAR  + $ROEGEMEIER  3 &RASIER  * +UROSE  & *UNYENT  " 0HILIPS   3 #RUZ 
 Since the atmospheric noise rises with the attenuation, the maximum occurs for Earth - tangenti al radiation, the minimum for perpendicular radiation ( Θ = 90° in Figure 6.5).  The  atmospheric noise has a broad minimum between 1 and 10 GHz, within which the up -to-now  chosen frequencies for Radar instrumentation for Earth exploration from outer space have also  been defined. The two -way attenuation in the a tmosphere is illustrated with the incident angle  as a parameter in Figure 6.5. 
 , vol. 21, pp. 1378–1388, 2004. 
 The simplest scatterometer uses a stationary CW  radar. Such systems are not very flexible, but they are discussed here in some detail to  illustrate calibration techniques that also apply to the more complex systems. The CW scatterometer is shown in block form in Figure 16.12. 
 While successful, this technique  is less computationally efficient than other modeling techniques, and hence, wave - guide models are not generally used for assessment systems requiring rapid execution  times. Waveguide models serve as “laboratory benchmark” models against which the  results of other modeling techniques can be compared. One such waveguide model is  the MLAYER, derived from the original works of Baumgartner.12 Parabolic Equation Models. 
 OPTICAL )NSTRUMENTATION %NGINEERS 30)%    VOL     PP n    * # #URLANDER AND 2 . -C$ONOUGH   3YNTHETIC !PERTURE 2ADAR 3YSTEMS AND 3IGNAL 0ROCESSING    .EW 9ORK *OHN 7ILEY  3ONS  )NC    2 + 2ANEY  h2ADAR FUNDAMENTALS TECHNICAL PERSPECTIVE v IN  0RINCIPLES  AND !PPLICATIONS  OF )MAGING 2ADAR  & (ENDERSON AND ! ,EWIS EDS   .EW 9ORK 7ILEY )NTERSCIENCE      PP n  ' &RANCESCHETTI AND 2 ,ANARI   3YNTHETIC !PERTURE 2ADAR 0ROCESSING  "OCA 2ATON  &, #2#  0RESS    2 + 2ANEY  h#ONSIDERATIONS FOR 3!2 IMAGE QUANTIFICATION UNIQUE TO ORBITAL SYSTEMS v  )%%%  4RANSACTIONS 'EOSCIENCE AND 2EMOTE 3ENSING  VOL   PP n    0 % 'REEN  *R  h2ADAR MEASUREMENTS OF TARGET SCATTERING PROPERTIES v )N  2ADAR !STRONOMY    * 6 %VANS AND 4 (AGFORS EDS   .EW 9ORK -C'RAW 
 Simulation is particularly important to account for the adaptive nature (e.g., CFAR,  adaptive beamforming, automatic radar management, adaptive tracking, adaptive clut - ter cancellation) of modern radar systems.195 In this case, traditional static measures  such as detection range against a given target will no longer adequately define the  capabilities of radar systems. Measures of radar dynamic characteristics, such as the  susceptibility to processor overload or the time to adapt in changing conditions, are  more important. Modeling and simulations to evaluate the radar response to standard - ized changing scenarios represent an attractive technical solution.195 Simulation is always of value; however, the effectiveness of ECM and ECCM is  ultimately done, when possible, with tests of real EW capabilities against real radar  systems under real-world conditions. 
 ERROR 
 The perfor- mance of these and other similar four-port devices is described in Ref. 3, Chap. 4. 
 The larger the video output, the larger will be the  f r_orn  mixer ··-~-~ IF  amplifier  D-c  amplifier  Delay voltage Vc Range  gate and  boxcar  AGC  filter Conical scan modulation  to angle-error detector  Fi~un' 5.5 Block diagram of lhC' AGC portion of a tracking-radar receiver. 158 INTRODUCTION TO RADAR SYSTEMS  reedback signal and the greater will be the gain reduction. The filter in the AGC loop should  pass all frequencies from direct current to just below the conical-scan-modulation frequency. 
 An amplifier between a row phase shifter and a series feed is desirable so that the gen- erated power does not have to take the loss of two phase shifters in series. In addi- tion, the row phase shifters must be capable of accurate phasing. Since relatively few row phase shifters are required, it is reasonable to make them considerably more accurate than the phase shifters in the array. 
 The result is that many delay lines are required for.highly-shaped filter  responses. There are limits to the' n'umber of delay lines (and pulses) that can he emplGyed.  Therefore other approaches to MTI filter implementation are sometimes desired. 
 ,Ê-"1, 
 D. Rosenberg, “Very high frequency  radiowave scattering by a disturbed sea surface,” IEEE Trans. , vol. 
 ( 10.23) the probability that a  particular signal was received. Since y will then be fixed, the denominator p(y) will be constant  and the a posteriori probability is  p(SN I y) = kp(SN)p(y I SN) j ( 10.24)  where the constant k is determined by the normalizing condition; that is, the integral of  p(SN I y) over all possible values must be unity. Therefore, if the a priori probability p(SN) is  known, the a posteriori probability may be found directly from Eq. 
 Conopulse.  Conopulse (also called scan with compensation ) is a radar tracking  technique that is a combination of monopulse and conical scan.19,20 A pair of antenna  FIGURE   9.12  Block diagram of a two-channel monopulse radar system ( from R. S. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 20.72  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 20 accurate predictions are required. 
 REFLECTION COEFFICIENT IS  THEREFORE   '2G G 
 The key performance features were its capability to (1) provide precise satellite-to-ocean surface-height measurements [precision . of 50 cm in the global mode (GM) and 20 cm in the intensive mode (IM) at an output rate of one per second] for use in mapping the shape of the ocean surface and (2) provide data which can be processed to estimate peak-to-trough ocean waveheight (waveheights in the range of 2 to 10 m can be estimated to an accuracy of 25 percent). Several key areas of technology included in the design are (1) high-frequency logic circuitry with a 160-MHz clock and four-phase division for 1.56-ns resolution, (2) a wideband (100-MHz) linear FM pulse compression system with a compression ratio of 100:1 and a compressed pulse width of 12.5 ns, (3) high-speed sample-and-hold circuitry for accurate sampling of wideband (50-MHz) noisy video return signals, and (4) design and packaging of high-voltage (12-kV) power supplies for space application. 
 P    WHERE K IS AN ARBITRARY COMPLEX CONSTANT AND  5  F    IS THE SPECTRUM OF  UT  4HE TIME  DELAY T IS REQUIRED TO EXCEED THE DURATION OF  UT  TO ACHIEVE A CAUSAL IMPULSE RESPONSE  THAT IS ZERO FOR NEGATIVE TIME 4HE MATCHED FILTER IMPULSE RESPONSE IS    HT K U TTMF   
 1971, pp. 9-25. OTHER RADAR TOPICS 569  72. 
 TRAL PURITY FOR THIS DEMANDING APPLICATION BUT ALSO BECAUSE PULSE WAVEFORMS ENJOY SOME UNDENIABLE ADVANTAGES &IRST  THEY CAN BE EMPLOYED FROM A SINGLE TRANSMIT 
 SIGNAL HAVE BEEN USED  IN THE PAST HOW 
 Frush, G. R. Gray, P. 
 PULSE FEEDFORWARD CANCELER AND A THREE 
 The directive gain of a transmitting antenna may be defined as  maximum radiation intensity GD = ..- .... .. -- . 
 82.Dillard,G.M.:Mean-Level Detection Utilizing aDigitalFirst-Order Recursive Filter,IEEETrans., vol.AES-12, pp.793-798, November, 1976. 83.Taylor,J.W.,Jr.,andJ.Mattern: Receivers, chap.5of"RadarHandbook," M.I.Skolnik (ed.~ McGraw-Hill BookCo.,Inc.,NewYork,1970. 84.Hanson, V.G.,andH.R.Ward:Detection Performance oftheCellAveraging LOGjGF' ARReceiver, IEEETrans.,vol.AES-8,pp.648-652, September, 1972. 
 Another technique for improving the bandwidth by a considerable factor is to use an  array of subarrays. The radiating elements of a phased array may be grouped into subar - rays where time-delay elements are added. This is shown in Figure 13.26. 
 6  The ability of a radar receiver to detect a weak echo signal is limited by the noise energy that  occupies the same portion of the frequency spectrum as does'the signal energy. The weakest  signal the receiver can detect is called the minimum detectable signal. The specification of the  minimum detectable signal is sometimes difficult because of its statistical nature and because  the criterion for deciding whether a target is present or not may not be too well defined. 
  Ê-/ 
 11.5. Although  pulse compression radar is of interest for other than the extraction of information, it is  included in this chapter because of its close relation to the ambiguity function. The fim1l  section revi@ws several radar techniques that might be used to distinguish one class of target  from another. 
 Aspect entropy image of the full scene. 4.2. Aspect Entropy Extraction at the T arget Level We choose a dihedral, a trihedral, a vehicle, and a top-hat from the scene as examples to illustrate the procedure of target aspect entropy extraction. 
 OUS NONCOHERENT INTEGRATORS THAT PROVIDE TARGET ENHANCEMENT  THRESHOLDING TECHNIQUES FOR FALSE ALARMS AND TARGET SUPPRESSION  AND ALGORITHMS FOR ESTIMATING TARGET POSITION AND RESOLVING TARGETS 4HEN  AN OVERVIEW OF THE ENTIRE TRACKING SYSTEM IS GIVEN  FOL 
 LONG DAILY MEASUREMENTS OF MULTIFREQUENCY +A  +U  8  #  AND ,  AND FULL 
 Land subsidence and ground ﬁssures in Xi’an, China 2005–2012 revealed by multi-band insar time-series analysis. Remote Sens. Environ. 
 TRACK INTERFEROMETRIC MODE FOR '-4) EXPERIMENTS  AMONG OTHER APPLICATIONS &ULL QUADRATURE POLARIZATION IS ONE OF THE MODE OPTIONS 4HE ONLY PAYLOAD INSTRUMENT IS THE RADAR  SO THE SPACECRAFT IS DESIGNED FOR A SUN 
 PLICATIONS OF CLUTTER 
 5.2such asystem isdescribed diagrammatically interms of type ofmodulation and use made ofthe returned signal. The upper part ofthe diagram shows the amplitude ofthe Fourier components radiated bythe transmitter; the lower part shows the amplitude ofthe. SEC. 
 X AND ,EFF IS THE  EFFECTIVE NUMBER OF PAST OBSERVATIONS AVERAGED IN THE CLUTTER MAP DEFINED AS   ,EFF 
 TION OF EXACT METHODS OF RADAR CROSS 
 The energy reaching the filter banks is restricted either by automatic gain control (AGC) or, when feasible, by limiting, and the thresholds in the circuitry following the filter banks are properly set with respect to the level in the total band. In a typical setting technique, random noise is injected into the amplifier that drives the filter banks, and each threshold is set to achieve the desired false-alarm rate. The level of noise is then varied and the threshold rechecked. 
 OF 
 The beacon pulse iswell over the minimum length of2psec necessary totrigger beacons. The pulse istransmitted from themodulat orona50-ohm cable, which enters the r-fhead via apressurized pulse connector fitting. The shielded cable then goes tothe quadrant-shaped pulse compartment. 
 MENT OF RADAR PERFORMANCE v  )%% )NT #ONF 2ADAR   #ONF 0UB NO   %DINBURGH  5+   /CTOBER n    PP n  & ! 3TUDER  - 4OMA  AND & 6INELLI  h-ODERN SOFTWARE TOOLS FOR RADAR PERFORMANCE ASSESSMENT v  0ROC OF )23   )NT 2ADAR 3YMP  -UNICH  'ERMANY  3EPTEMBER n    PP n   ! ' (UIZING AND ! 4HEIL   #!20%4  3OFTWARE    5SER -ANUAL  4HE (AGUE  4HE .ETHERLANDS  4./ $EFENSE  3ECURITY AND 3AFETY  . Óx°£,>`>ÀÊ }Ì>ÊÊ -}>Ê*ÀViÃÃ} >iÃÊ°ÊÌiÀÊ ivvÀiÞÊ"°Ê i> .AVAL 2ESEARCH ,ABORATORY Óx°£Ê  /," 1 /"  4HE EXPONENTIAL GROWTH IN DIGITAL TECHNOLOGY SINCE THE S  ALONG WITH THE COR 
 A chapter in the first edition of this handbook was devoted to this approach, which  since then has received much less attention; frequency is too important a parameter  for achieving high-range resolution, electronic counter-countermeasures, and multiple  radar occupancy to give it up for antenna scanning. Frequency scanning is seldom  used anymore. IF Scanning . 
 8.29 differ in frequency by f,, the beam  rcpctitively scans its coverage at a rate ofJ,. That is, the antenna beam occupies all possible  scan positions during the scan time I([%. Another way of looking at this is to note that if the  relative phase between adjacent elements of an array is changed by 2n radians, the radiation  par tern will assume all possible scan positions. 
 PAIR PROCESSING FOR ESTIMATION OF WEATHER MEAN  VELOCITY AND SPECTRAL WIDTH TURBULENCE  4HERE ARE TWO DRAWBACKS OF ELLIPTIC FILTERS &IRST  THE LONG TRANSIENT SETTLING TIME &OR A SCANNING WEATHER RADAR  IT TAKES ABOUT FOUR BEAMWIDTHS OF SCANNING AFTER THE TRANSMITTER STARTS PULSING BEFORE CLUTTER ATTENUATION REACHES  TO  D" 3ECOND  IF THE INPUT CLUTTER SIGNAL REACHES THE LIMIT LEVEL IN THE )& RECEIVER  THERE WILL BE A SIGNIFICANT TRANSIENT INCREASE OF CLUTTER RESIDUE /NE OF THE ELLIPTIC FILTERS EMPLOYED IN THE ORIGINAL 4$72 RADAR IS USED AS AN EXAMPLE 4$72 OPERATES AT # BAND  
 13.9 Incertain applications where the clamp isused asaseries element, itisessential that thecurrent drawn from thereference point beassmall aspossible. Even such small currents asthose drawn bythe grid cir- cuits ofFig. 13”25a may beobjectionable. 
 29, no. 1, pp. 234–243,  January 1993. 
 Responds to maneuvers  but not at the edge of filter  stability. Model no. 2: Random  change in acceleration at  each measurement interval. 
 Obviously, the better the resolution and accuracy of any parameter measurement, the more efficiently the pulse-sort processor can carry out its task. However, there are limitations on the measurement process from outside the ESM system (e.g., multipath), from inside the system (e.g., timing constraints, dead time during reception), and from cost-effectiveness considerations. Angle of arrival is probably the most important sorting parameter available to the deinterleaving process since the target bearing does not vary from pulse to pulse. 
 II for detecting U-boats during 1941 and early 1942, it was increasingly noticed during late 1942 that U-boat radar contactswere disappearing before they could be sighted and engaged. It was concluded that the enemy may have introduced ‘listening gear ’, that was alerting them to the presence of an aircraft with ASV. The use of a sensitive radar warning receiver cangive considerable range advantage compared with the reciprocal detection range of the radar, since the received power from the radar only varies as 1/ R 2compared with the 1/ R4variation of power returned to the radar. 
 406 INTRODUCTION TO RADAR SYSTEMS  This is a reasonably good approximation for almost any value of Br. Therefore the rms error  in the time-delay measurement for a "rectangular" pulse of width r, limited to a bandwidth B,  is approximately 3 A  t 112  (4BE/No) bandwidth-limited rectangular pulse ( 1 1.20) 0 '0 3 + - - a  E a  The pulse width r in the above expression is that of the perfectly rectangular pulse before band  limiting. It is a good approximation to the width of the band-limited pulse when Br is large. 
 (ILL      PP n  ' 7 3TIMSON   )NTRODUCTION TO !IRBORNE 2ADAR   ND %D 2ALEIGH  .# 3CI4ECH 0UBLISHING  )NC     PP n  & # 7ILLIAMS AND - % 2ADANT  h!IRBORNE RADAR AND THE THREE 02&S v  -ICROWAVE *OURNAL   *ULY  AND REPRINTED IN - ) 3KOLNIK   2ADAR !PPLICATIONS .EW 9ORK )%%% 0RESS     PP n  $ # 3CHLEHER   -4) AND 0ULSED $OPPLER 2ADAR  !RTECH (OUSE  )NC    PP n  ' -ORRIS AND , (ARKNESS   !IRBORNE 0ULSED $OPPLER 2ADAR   ND %D .ORWOOD  -! !RTECH  (OUSE  )NC    P   7 ( ,ONG AND + ! (ARRIGER  h-EDIUM 02& FOR THE !.!0' 
 MENT v 0ROCEEDINGS OF THE )%%%  VOL   PP n    ' 3 (AYNE  h2ADAR ALTIMETER MEAN RETURN WAVEFORMS FROM NEAR 
 Figure 5.16 illustrates the comparison between the original tube system and the solid-state retrofit. The solid-state module is a 300-W CW amplifier that uses a l-driving-4 con- figuration of silicon bipolar transistors operated common-emitter by using Class-C bias and a 28-V dc power supply. The operating characteristics of the module are delineated in Table 5.6, and Figs. 
 1970.  4. Bayma, R. 
 WIDE SYNTHETIC APERTURE RADAR v IN  0ROCEEDINGS OF THE  )%%% 2ADAR  #ONFERENCE    PP   . 6ANDENBERG  $ 2 3HEEN  3 3HACKMAN  AND $ 7ISEMAN  h0 
 TIVE WIDTH TO ABOUT A QUARTER WAVELENGTH WIDER THAN THE PHYSICAL WIDTH 4HE EFFECTIVE % 
  IS A MILITARY VERSION OF THE 2AYTHEON (AWKER 80  MID 
 Therefore the gain of a constant-area antenna does not increase as  rapidly as the square of the frequency. For renectors of equal gain (same diameter in  wavelengths) Eq. (7.32) shows that the relative sidelobe level caused by errors will increase  ·;1s the fourth power of the frequency, or 12 dB/octave.112  ;\n imrortant conclusion is that the details of the radiation pattern, especially in the  region outside the main beam, are more likely to be determined by the accuracy with which the  antenna is constructed than by the manner in which the aperture is illuminated. 
 Such vector -network analyzers (VNwa) can  be employed as the core of a new type of RCS measurement system, especially for use in lab o- ratories.  The fundamental principle had been described for the first time in 1974 and the first realization was intro duced in 1985.  Already with the still simple and non -sophisticated struc- tures advantages could be shown compared to conventional Radar systems, like linear FM  Radar or pulse Radar. 
 Whennootherinput dataisavailable, theIREPSutilizesastoredlibraryofhistoric refractivity andclimatology statistics asafunction ofthelatitude, longitude, season,andtimeofday.Whenhistoricdata isusedtheoutputisaprediction ofpropagation performance inprobabilistic terms.Also storedarethenecessary systemparameters forthevarious electromagnetic systems whose predicted propagation performance isdesired. 12.6DIFFRACTION Infreespace,electromagnetic wavestravelinstraight lines.Intheearth'satmosphere, radar wavescanpropagate beyondthegeometrical horizon byrefraction. Another mechanism that permitsradarcoverage tobeextended beyondthegeometrical horizon isdUfractioll. 
 The combining of the power from a large number of individual solid-state devices is  attractive when using an array antenna since the power is" combined in space," rather than by  a lossy microwave network. A fixed phased array requires electronic beam steering that  complicates the radar. If the flexibility of an electronically steered array is not needed, the  advantages of an array antenna for combining the rad1ated power from many individual  sources can be had by mechanically sc~nning the entire antenna. 
 12.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 Figure 12.5 also shows that feed blockage increases the sidelobe level; for example,  with a –10 dB edge taper, one obtains –25.5 dB sidelobes rather than −27.5 dB side- lobes. Figures 12.6 and 12.7 further illustrate this impact. This blockage effect can be  modeled as a “hole” in the aperture that can be represented by a broad pattern with  less gain. 
 IMAGE FILTER HAS COEFFICIENTS THAT ARE COMPLEX CONJUGATES OF THE ORIGINAL FILTER COEFFICIENTS  &IGURE C SHOWS THE FIRST FILTER DESIGNED FOR RESPONSE AT ZERO DOPPLER  #ONSIDERATIONS HERE ARE THAT THE DOPPLER STRADDLING LOSS OF THE FILTER BANK BE MINIMIZED   &)'52%  3IX 
 .—..— ——. ———— ----- ._. .— ...... 
 A probe in the tube was held at −1000 V so Figure 3.4. TR.3191 [ 5]. Figure 3.5. 
 68–78, 1997. 172. J. 
 BASED ALTERNATIVES FOR MEASURING VECTOR WINDS BY  MICROWAVE MEANS  ACTIVE AND PASSIVE 2ADARS OFTEN ARE UNPOPULAR ON SPACECRAFT THAT HOST OTHER INSTRUMENTS  OF WHICH SOME MAY BE COMPROMISED BY RADIO FREQUENCY INTER 
 BAND  RADAR  WEIGHING FOUR MILLION POUNDS SEE &IGURE   4HE 3"8 PLATFORM THAT IT SITS ON STANDS MORE THAN  FT TALL  AND DISPLACES MORE THAN   TON S )T CONSISTS OF A SEMI 
 SIC INSTRUMENT PRECISION OF THE LEADING RADAR ALTIMETERS OF THE PAST  YEARS 6ERTICAL AXIS IN CM -ODERN 0/$ ACCURACY RELIES ON '03 AND THE &RENCH $/2)3 SYSTEM 0RECISION IS LIMITED BY THE ALTIMETERS DEGREES OF FREEDOM INCOHERENT WAVEFORM AVERAGING   AFTER  $UDLEY  #HELTON   /REGON  3TATE  5NIVERSITY  PERSONAL COMMUNICATION 
 An algorithm based on keystone transform and time-domain chirp scaling to deal with the space-variant range cell migration in ISAR imaging with ultrahigh range resolution is proposed in [ 22]. Phase compensation and image autofocusing algorithms using randomized stepped frequency emitted ISAR signals are described in [ 23]. A problem of coherent integration for detecting high-speed maneuvering targets, involving range migration, quadratic range migration, and Doppler frequency migration within the coherent processing interval, and a coherent integration algorithm based on the frequency-domain second-order phase diﬀerence approach are discussed in [ 24]. 
 This is sometimes called coherent on receive .  The MTI improvement factor obtained with a magnetron and a coherent-on-receive  operation usually is not as good as can be obtained with an MTI system that uses a  power amplifier as the transmitter. Automatic frequency control (AFC) is often employed to keep the receiver tuned  to the frequency of the transmitter since the magnetron frequency can slowly drift  with changes in ambient temperature and self-heating. 
 15.11 Positive identification. Aircraft control isfrequently complicated bythelarge number ofaircraft operating atthesame time within range ofasingle radar set. Departure ofaircraft from planned fllght schedules makes reliance onmovements information unsatis- factory foridentification. 
 Theswitched linescanbeanystandard RF transmission line.Stripline hasbeenusedsuccessfully, ~specially atthelowermicrowave frequencies. Anadvantage oftheparallel-line configuration isthatthesignalpassesthrough buttwoswitches and,inprinciple, shouldhavealowerinsertion lossthanthecascaded digitally swHched phaseshifterdescribed below.Adisadvantage istherelatively largenumber Une-by-N SWitch One-by-N switch l,-?' (:k~'--­ ~'-----+ ---:...._------+-.....r- Figure8.5Digitally switched parallel-line phaseshifterwithNswitchable lines.. 288 1NTRODUCTlON TO RADAR SYSTEMS  Figurc 8.6 Cascadcd four-hit tligitally  switched phase shifter with A/ 16 quanti~a-  tion. 
 K. A. Browning and R. 
 The early area MTI systems stored a complete scan of  radar video in a memory, such as a storage tube, and subtracted the stored video scan to scan.  Instead of subtracting successive scans, the subtraction can be on a pulse-to-pulse basis with  much less memory required, if a shortpulse is used.77 The pulse widths required for aircraft  detection are of the order of nanoseconds. This technique reiies on the Fact that the echoes -  from moving targets change range from pulse to pulse and those from stationary and slowly  moving targets do not. 
 RECEIVER 
 6. Arii, M.; Nishimura, T.; Komatsu, T.; Yamada, H.; Kobayashi, T.; Kojima, S.; Umehara, T. Theoretical characterization of multi incidence angle and fully Polarimetric SAR data from rice paddies. 
 ch20.indd   80 12/20/07   1:17:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 
 ANCES  IT IS REASONABLY STRAIGHTFORWARD TO PRODUCE AFFORDABLE ANTENNAS THAT MEET )-/ REQUIREMENTS 4HE REQUIRED VERTICAL  BEAMWIDTH IS NORMALLY OBTAI NED BY A LINEAR FLARE  4HE FLARE ANGLE IS CHOSEN SUCH THAT IT CREATES A REASONABLY PHA SE 
 9)  Equation (8.9) states that the main beam of the antenna pattern may be positioned to an  angle 00 by the insertion of the proper phase shift </> at each element of the array. If variable,  rather than fixed, phase shifters are used, the beam may be steered as the relative phase  between elements is changed (Fig. 8.2). 
 DELAY BINOMIAL 
 It is noted that the performance of the phase-difference estimation  procedure is best when moderate Taylor weighting functions are used. For uniform  weighting, the procedure would be substantially inferior to the maximum likelihood  approach. The increase in the constant k for the more severe weighting cases is the  result of the SNR loss resulting from the use of weighting. 
 Introduction.-The development ofanew radar system may be called forbecause ofrecognition ofanew application forwhich radar has not been used but for which itssuccessful use appears possible. In other cases, adevelopment may bejustified foranapplication where radar isinsuccessful usebut where improved results could beexpected bythe use ofmore modern equipment. Early ideas dnanew system and initial proposals may come from a development laboratory orfrom the potential users ofthe equipment. 
 M. Skolnik (ed.): Radar Handbook , 1st Ed., New York: McGraw-Hill, 1970. ch12.indd   43 12/17/07   2:32:03 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Patent 690,754, May 27, 1976. 30. Skillman, W. 
 Lee, “Eigenvalues and eigenvectors of covariance matrices for signal closely spaced in  frequency,” IEEE Trans ., vol. SP–40, no. 10, pp. 
 SEQUENCE  OF COURSE  IS THAT THE EFFECTIVE 02& IS REDUCED BY THE SAME FACTOR  N 4HIS  PRACTICE IS SELDOM ACCEPTABLE FOR SPACE 
 Thebeamwidth isapproximately inversely proportional tocos00,where00istheanglemeasured fromthenormal tothe antenna. Thismaybeprovedbyassuming thatthesineintiledenominator ofEq.(8.9)canbe replaced byitsargument, sothattheradiation pattern isoftheform(sin1u)/u1,where Ii=Nrr(d/A)(sin 0-sin(0),The(sin2u)/u2antenna pattern isreduced tohalfitsmaximum valuewhenIi=:+~0.443rr.Denote by0+theanglecorresponding tothehalf-power pointwhen (}>0u.and0_,thcanglecorresponding tothehalf-power pointwhen0<00;thatis,O. corresponds to/I=+0.443rrand0_toII=-0.4431£.Thesin0-sin00termintheexpres­ sionforIIcanbewritten 17 sin0-sin00=sin(0-00)cos00-[1-cos(0-00))sin00 (8.11) Thesecondtcrmontheright-hand sideofEq.(8.11)canbeneglected when00issmall(beam isncarbroadside), sothat sin0-sin00~sin(0-(0)cos00 (8.12) Usingtheaboveapproximation, thetwoanglescorresponding tothe3-dBpointsofthe antenna patternare -0.443..1.0_-00=sin-I..-.---- Ndcos00-0.443..1. 
 FREQUENCY CONTOURS VERSUS RANGE FROM THE RADAR FOR  54#   33.   *ANUARY NIGHT  AND  54# DAY  ARE PRESENTED IN &IGURES  AND   TO ILLUSTRATE THE TILT OF THE IONOSPHERE &OR THE NIGHT CASE  THE CONCENTRIC &)'52%   0REDICTED IONOGRAMS AS IN &IGURE   BUT FOR *ANUARY  A   54#  FOR DAY AND B   54# FOR NIGHT 3EE TEXT FOR AN EXPLANATION OF THE TABLE IN THE LOWER  RIGHT OF THE FIGURE .   (& /6%2 
 Forexample. spectral measurements ofasmallnocturnal migrant (a pipit)showed awing-beat frequency of15.8Hz;andamigrating rapit(ahoneybuzzard) gave arrcquency of3.2HZ.92t\mallardproduced afrequency of6.5Hz,plusharmonics at13and 100------..---r90 . 80 70 60 50. 
 On reception, a receiver is inserted at each end of the feed. TIle echo signal from a particular  direction isf'ieceivcd at one of tlte slots and is divided in the waveguide feed. The'two signals  travel in opposite directions and arc received at each end of tlie feed. 
 Thebandwidth ofsucharadome islimited,asis therangeofincidence anglesoverwhichtheenergyistransmitted withminimal reflection. TheAsandwich isathree-layer wallconsisting ofacoreoflow-dielectric-constant mater­ ialwithathickness ofapproximately one-quarter wavelength. Thisinnercoreissandwiched between twothinouterlayers,orskins,ofahigh-dielectric-constant material relativetothatof thecore.Theskinsmighttypically haveadielectric constant ofabout4,andthecoremight haveavalueofabout1.2.Theskinsarethincompared toawavelength. 
 59–267, April 1960.  2. P. 
 Frank, “Phased array antennas,” Chapter 7 in Radar Handbook , M. I. Skolnik,  (ed.), 2nd Ed., New York: McGraw-Hill, 1990. 
 and K. H. Jelm: A Study or Radar Elevation-angle Errors Due to Atmospheric  Refraction. 
 Consider travel in the y direction, with z vertical, and the altitude (fixed) z = h. Then v = lvv R-I^c-H lyy - lzh where (lx,ly,lz) are unit vectors. Hence R vy R Vx2 + y2 + h2 where vr is the relative speed. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. The Propagation Factor, Fp, in the Radar Equation.  THE PROPAGATION FACTOR, FP, IN THE RADAR EQUATION  26.136x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 26 The resultant inversion is referred to as the tradewind inversion and may create a  strong ducting condition at the top of the marine boundary layer. 
 The advantage of considering the signal-to-noise  ratio at the IF is that the assumption of linearity may be made. It is also assumed that the IF  filter characteristic approximates the matched filter, so that the output signal-to-noise ratio is  maximized.  2.3 RECEIVER NOISE  Since noise is the chief factor limiting receiver sensitivity, it is necessary to obtain some means  of describing it quantitatively. 
 Waters: The Estimation of ~roposphedc Electrical Path  Length by Microwave Radiometry, Proc. IEEE, vol. 58, pp. 
 BEAM JAMMING 4HE NOISE JAMMER SITUATION  IS BASICALLY AN ENER GY BATTLE BETWEEN THE RADAR AND THE  JAMMER )N THE MAIN 
 58.Caspers, 1.W.:BistaticandMultistatic Radar.chap.36of"RadarHandhook." M.I.Skolnik (l:d.). McGraw-Hili BookCompany, NewYork,1970. 59."System forDetecting Objects byRadio." U.S.Patent 1.9~l.884. 
 Jasik (eds.), Antenna Engineering Handbook , 2nd Ed., New York:   McGraw-Hill Book Company, 1984. 11. E. 
 16. King. R. 
 Brown, “The average impulse response of a rough surface and its applications, IEEE  Antennas and Propagation , vol. 25, pp. 67–74, 1977. 
 SPEED SERIAL LINKS WILL BE THE PRIMARY COMMUNICATION MECHANISM FOR MULTIPROCESSOR MACHINES INTO THE FUTURE  WITH EVER 
 PING SEQUENCING SOFTWARE 4HE RESULT WAS A SET OF ABOUT  UNIQUE CONFIGURATIONS  EACH TIED TO SPECIFIC SEGMENTS OF THE ORBIT )N OPERATION  SUITABLE COMMANDS WERE PRE 
 6. Noise (N0): For radars operating in the HF band it is possible to design antennas and receivers with low enough noise figures that environmental noise is dominant. 7. 
 TRUM OF 8 
 BAND RECEIVED SIGNALS ARE AMPLIFIED AND RETRANSMITTED WITH MINIMUM DELAY $ELAYS CAN BE KEPT TO A FEW NANOSECONDS  LESS THAN THE EQUIVALENT DIMEN 
 n   P    n AS LONG AS  PLPS\SIN SIN \PP 
 The two-frequency MTI has the  advantage of being less sensitive than a single-frequency MTI to a mean clutter-doppkr­ frequency other than de, assuming the single-frequency MTI employs no compensation such  as TACCAR. This also results, however, in the loss of detection of targets with low doppler­ frequency shift that otherwise would have been detected with the single-frequency MTI.  In general, the two-frequency MTI does not offer any obvious net advantage over  properly designed single-frequency MTI systems for most MT[ radar applications. 
 FF SCAT INC 4HE  KERNEL 'FFJJ   IS DISCUSSED BELOW %Q  REVEALS THAT THE "ARRICK 
 Noprovision ismade fortilting the beam inelevation. Fixed 16-ft aluminum flaps (Fig. 9“19)above and below thearray serve toshape the beam inelevation toaroughly cosecant-squared distribution. 
 (3) The best  noise-figure usually requires a  bias condition that is closer to the  pinch-off voltage of the FET than  for a power amplifier. The pinch- off voltage is the voltage that  when applied to the gate terminal  causes the current in the tran - sistor channel to stop flowing.  Thus, the transistor is “pinched- off” and variability around this  operating point can cause large  circuit performance variability if  designed poorly. 
 FERENCE 2&)  GENERATED BY A NEARBY MICROWAVE TRANSMITTER 2ADARS ALSO REQUIRE MORE POWER FROM THEIR HOST SPACECRAFT THAN PASSIVE SYSTEMS 4HESE AND RELATED CONSIDER 
 130  clutter fluctuations, 131 134  clutter-lock. 142  cluttcr map. 127  coliercnt reference, 385 386  colto, 105. 
 During  calibration, a test signal is presented to the RF input of all channels. This signal is typi - cally a swept frequency tone or a noise input that covers the channel bandwidth. The  ADC samples of all channels are collected simultaneously and complex weights are  calculated for the equalization filters that force the frequency response of each channel  to be matched. 
 The velocity vs. frequency characteristic of such  transnlission lines can be used to advantage to provide' more frequency sensitivity; that is, a  snialler wrap-up factor can be obtained for a given scan angle and frequency excursion.  A sketch of a folded waveguide for exciting an array of slotted waveguides is shown in  Fig. 
 Standard targets may be metal spheres, Luneburg-lens reflectors, metal plates, corner reflectors, or active radar calibrators (ARCs—actually repeaters).58 Of the passive calibrators, the Luneburg-lens reflector is best, since it has a large cross section for its volume and has a very wide pattern so that alignment is not critical. Luneburg-lens reflectors are used for making strong ra- dar targets of small vessels, and they may be obtained from companies that sup- ply that market. For discussion of the relative merits of different passive calibra- tion targets, see Ulaby, Moore, and Fung.59 The ideal receiver would respond linearly to its input, so that a single calibra- tion at one input level would suffice for all levels. 
 45.Cohen, E.D.:Trapatts andImpatts-State oftheArtandApplications, Microwave J.,vol.20, pp.22-28,February, 1977. 46.Dilorenzo, J.V.:GaAsFETDevelopment-low NoiseandHighPower,Microwave J.,vol.21, pp.39-44,February, 1978. 47.Bates,D.J.,R.I.Knight,andS.Spinella: Electron-Bombarded Semiconductor Devices, "Advances in Electronics andElectron Physics, vol.44,"Academic Press,Inc.,NewYork,1977. 
 The typical multilevel threshold has  several unique features. In addition to the obvious alert-confirm properties (a double  thresholding method in which a lower first threshold nominates radar returns as pos - sible targets to be confirmed by a return observation with a higher threshold), it also  uses multiple phase center discriminants as well as near sidelobe threshold multipli - ers.94 Even with STAP, the non-gaussian nature of clutter requires higher thresholds in  the main beam and near sidelobes.98 Threshold crossings are correlated in range and  doppler and buffered along with corresponding phase center discriminants, which are  presented to tracking filters or activity counters. There are three regions of thresholding: main-beam clutter-limited detection, near  sidelobe clutter-limited detection, and thermal-noise-limited detection. 
 Ê/ 
 Because forest terrain is a more uniform scatterer, the cones extend into the forward quadrant (9, > 90°). The ridge extent is smaller and its magnitude is about 16 dB below that of rural land. Other values of <TB° for forest terrain are similar to those of rural land for 9^ < 90°. 
 FT ALTITUDE !N !.&03 
 Barton. D. K.: "Radar System Analysis," Prentice-Hall, Inc .. 
 TRONIC WARFARE  ANTIRADIATION MISSILES TO HOME ON RADAR SIGNALS  AND LOW CROSS 
 The discussion above regarding the benefits and limitations of the short  pulse also apply to the azimuth beamwidth. The use of high resolution in angle{nd/or range  is the principal method available for detecting a fixed target in clutter, assuming the target  "cross section per unit area" is greater than that of clutter a0. Too narrow a beamwidth, just  as too narrow a pulse width, is not desired since it can also alter the clutter statistics in an  unfavorable manner. 
 (Thediameter Dintheparabolic torusisthediameter oftheilluminated arearatherthanthediameter ofthetorusitself.)Thehighestsidelobes produced bythe parabolic torusdonotliewithintheprincipal planes.Theinherent phaseerrorsof theparabolic-torus surfaceduetoitsdeviation fromatrueparabola cancausesidelobeson theorderof15dBinintermediate planes.38Thesesidelobes usuallylieinthe45°planeandare calledeyes,because oftheircharacteristic appearance onacontour plotoftheradiation pattern. Inprinciple theparabolic toruscanbescanned 180°,butbecauseofbeamspillover near theendofthescanandself-blocking bytheopposite edgeofthereflector, themaximum scan angleisusuallylimitedtothevicinity'of120°. Onlyaportionoftheparabolic-torus isilluminated bythefeedatanyparticular time. 
 The range  defined in this figure is the range of mean values lying between  5 and 95% of points on the distribution. This accuracy range is independent of any accu - racy problems associated with calibration and knowledge of the antenna pattern. The precision of the measurement depends upon the number of independent  sam - ples, not on the total number of samples. 
 STATE UPGRADE FOR THE #/"2! *5$9  3 
 This isasfaraswecare topursue this complicated matter, apart from displaying, inFig. 2.10, curves showing thedependence upon 8ofthereflection coefficient and thephase shift, forreflection of10-cm radiation atawater surface (there isvery little difference between salt and fresh water atmicrowave frequencies). 10 =08-gy= z.~06 i ~ =0.4(a) . 
 153 shows the general form ofbeam shape that gives the most desirable type ofcoverage under these conditions. Itslower edge isdetermined bythe optical horizon, with corrections foratmospheric refraction and interference due tosurface reflection. Atadistance dinland miles from the radar set, the horizon height hinfeet isgiven byh=~dzfor normal atmospheric refraction (neglecting the interference effect, which issmall formicrowaves; seeSec. 
 Thus a combination RF and IF blanking system is usu- ally employed. The transmitter leakage through the blanking circuits can be al- lowed to be as large as main-beam clutter if there is zero-doppler filtering to re- move it. Alternatively, it must be a fraction of the noise power in a detection filter if there is no such filtering. 
 255. Sensors 2019 ,19, 346   (a) (b)     (c) (d)  Figure 6. Diagram of the denoising procedure. 
 As will be discussed in chapter 4, a simple meter indicating target range and bearing was eventually introduced for the pilot as part of the blind bombing facility on ASV Mk. VI. 2.2.3 Radar installations Two examples of typical installations are shown in ﬁgure 2.14. 
 H. W.: An Improved Simultaneous Phase Comparisa Guidance Radar, IRE Trans., vol.  ANE-3, pp. 
 The general search procedure includes the following steps. (1) The magnitude of each initial individual gene should be set, which means the initial value range of each parameter should be ﬁxed, and the corresponding ﬁtness function value of each individual population can be calculated. (2) Whether the iteration termination condition for the minimum ﬁtness function is satisﬁed should be determined. 
  MONOSTATIC WEATHER RADAR TRANSMITS AND RECEIVES ON A NARROW BEAM ANTENNA  WHILE  ONE OR MORE BISTATIC RECEIVE SITES n KM FROM THE #0 
 441, July 1997, pp. 256–259. ch20.indd   81 12/20/07   1:17:24 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 CLUTTER RATIOS OWING TO THE FACT THAT THE 2AYLEIGH SCATTERED WEATHER SIGNAL POWER IS INVERSELY PROPORTIONAL TO K   WHEREAS THE GROUND CLUTTER RETURN IS ONLY WEAKLY DEPENDENT ON WAVELENGTH )F  ONE ASSUMES THAT THE CLUTTER SIGNAL IS WAVELENGTH INDEPENDENT AND THE ANTENNA BEAM 
 1.2.Formostcommon typesof radartargetssuchasaircraft, ships,andterrain,theradarcrosssectiondoesnotnecessarily bearasimplerelationship tothephysical area,exceptthatthelargerthetargetsize,thelarger thecrosssectionislikelytobe. Scattering anddiffraction arevariations ofthesamephysical process.1SWhenanobject scatters anelectromagnetic wave,thescattered fieldisdefinedasthedilTerence between the totalfieldinthepresence oftheobjectandthefieldthatwouldexistiftheobjectwereabsent (butwiththesourcesunchanged). Ontheotherhand,thediffracted fieldisthetotalfieldinthe presence oftheobject.Withradarbackscatter, thetwofieldsarethesame,andonemaytalk aboutscattering anddiffraction interchangeably. 
 AES-14, pp. 199-208,  January. 1978. 
 Wald, A.: "Sequential Analysis," John Wiley & Sons, Inc., New York, 1947.  38. Marcus, M. 
 TION COMPLEXITY !N EXAMPLE OF A COMPLETE DOPPLER FILTER BANK IMPLEMENTED WITH NINE UNIFORMLY SPACED FILTERS IS SHOWN IN &IGURE  4HE PERFORMANCE OF THIS DOPPLER FILTER BANK AGAINST THE CLUTTER MODEL CONSIDERED IN &IGURE  IS SHOWN IN &IGURE  4HIS GRAPH SHOWS THE SIGNAL 
 13.26 .—Two-wa Ysite polarity oneither side ofanull position of double-triode clamp with tran8f0rmer+0uplcd switching.the~ynchro rotor; inother words, the carrier undergoes a180° phase change asthesynchro passes through anull. Thus, when thecircuit ofFig. 13.26 isused asa demodulator, the output voltage ispositive ornegative depending upon whether thesynchro rotor isoriented positively ornegatively with respect tothenull position. 
 Stand-on jammers are also subject to direct attack  by interceptor aircraft.  Increasing the radar energy in the direction of the jammer in the hope of increasing the  radar ecllo power above the jamming noise is called bunitltrotcgh. This may be accomplished  with reserve transmitter power or by dwelling longer in the direction of the jammer. 
 The ex- ample illustrated in Fig. 3.5 includes a gaussian filter at IF with a 3 dB bandwidth of 1.6 MHz and a four-pulse MTI with variable interpulse periods and time-FREQUENCY (kHz)RANGE FACTOR (dB) CURVE DELAY (us) . FREQUENCY (kHz) FIG. 
 #  #ANADA n     # 6ARIOUS TO 1UAD -!03!2  "RAZIL'ERMANY n n , 3INGLE  DUAL  QUAD3ENTINEL 
 Remote Sens. 2005 ,43, 2963–2972. [ CrossRef ] 7. 
 This characteristic of the NLFM waveform sometimes necessitates processing using  multiple matched filters offset in doppler shift to achieve the required time sidelobe  level. Because of the doppler sensitivity of the ambiguity function, the nonlinear fre - quency modulation waveform is useful in a tracking system where range and doppler  frequency are approximately known, and the target doppler shift can be compensated in  the matched filter. The nonsymmetrical NLFM waveform is used in the MMR system,  for example, which detects and tracks ordnance such as mortars, artillery, and rockets. 
 UP MODES .ORTH 
 280. Sensors 2019 ,19, 1154 The radial motion compensation can be achieved by removing the phase term e−j4πf cR0(t)and the received signal after motion compensation can be expressed as follows: SR(f,t)= rect(t Tobs)rect(f−f0 B)/integraldisplay Vξ(z)e−j4πf c(zT•iR0(t))dz (2) The distance R0(t)can be approximated by a polynomial. This can be written as follows: R0(t)≈α+βt+1 2γt2(3) where α=R0(0),β=• R0(0)and γ=•• R0(0)/2,α=R0(0)cannot cause the defocusing in the image, theβand γrepresent the target radial velocity and acceleration which also are related to the Doppler frequency parameter in (4):/braceleftBigg fdc=2f cβ fdr=4f cγ(4) The quadratic term1 2γt2is the main cause of defocus in SAR images [ 3,32]. 
 On these very tiny wavelengths no signal-frequency  amplification is possible, so the first stage of almost any  radar receiver working on less than 10 centimetres con-  sists of the mixer, into which (as in normal broadcast  practice) the signal voltage and the voltage from a local  oscillator are fed. In centimetric equipment the local  oscillator is usually a klystron, and the mixer used is  either a simple diode or a crystal capsule. It is some-  what ironic to return to the crystal detector in this  advanced phase of radio technique, but although the  research organizations of the G.E.C. 
 PRIATELY TAPERED 4HIS LEADS TO THE WELL 
 PERFORMANCE RADAR TRANSMITTER 4HERE IS USUALLY NO QUESTION THAT THE AMPLIFIER IS USUALLY THE PREFERRED CHOICE  EXCEPT IN SITUATIONS WHERE THE LOW COST OF A MAGNETRON TRANSMITTER IS MORE IMPORTANT THAN THE LOWER -4) IMPROVEMENT FACTOR IT PROVIDES COMPARED TO A LINEAR 
 ,/" - 2ECEIVERS GENERATE INTERNAL NOISE THAT MASKS WEAK SIGNALS BEING RECEIVED FROM THE RADAR  TRANSMISSIONS 4HIS NOISE CONTRIBUTION  WHICH CAN BE EXPRESSED  AS EITHER A NOISE TEM 
 NIFICANT EFFECT ON THE RADARS RESISTANCE TO %#-  %3-  AND !2- 4HIS GROUP OF TECH 
 AP-6, pp. 370 376, October, 1958.  94. 
 Wuhan surface subsidence analysis in 2015–2016 based on sentinel-1a data by sbas-insar. Remote Sens. 2017 ,9, 982. 
 M DIAMETER PARA 
 A compromise must be made, and something other  than a uniform illumination is generally selected.  Thus the parameter of aperture efficiency, whic~ sometimes is held sacred by the antenna  designer and to some who write antenna specifications, is often of secondary importance to the  systems engineer wishing to optimize total radar performance. It can usually be traded for  some more important characteristic. 
 A receiver with a logarithmic input-output characteristic followed by a  high-pass filter (fast-time-constant, or FTC, circuit), will provide a constant false-alarm rate  (CF AR) at the output when the input clutter or noise is described by the Rayleigh probability  density function. CF AR is important since, without it, clutter can excite the radar display and  obscure the presence of desired targets even if the targets are of greater strength than the  clutter. CF AR prevents obscuration of detectable targets by weaker clutter by maintaining  the clutter output from the receiver at a constant ·value well below the saturation level of  the display. 
 2.6 and 2.7. Curves for the other fluctuation cases and for additional values of detection probability are given in Refs. 13 and 14. 
  
 Ifthe pulses are transmitted atahigher power level than the video signals, the difference involtage amplitude can beused asacriterion. This high-level transmission ofpulses isusually done with amplitude- modulated r-fequipment, since thebrevity ofthepulses allows high pulse powers, with attendant signal-to-interference gain, tobeobtained cheaply (Sees. 17”11, 17.12), but itisnot feasible with frequency-modulated equipment. 
 L. A. Wainstein and Y . 
 IZED BORESIGHT 
 DIMENSIONAL NORTH 
 ING ITS FREQUENCY AND RESPONDING AT THE SAME FREQUENCY  THEREBY REDUCING THE INTERFER 
 Q)  >  .~ 50  Q) a:  O~~~~ ~~~~ __ ~~ __ ~ __ ~  -32 -16 0 16 32  Waveform sample index  Figure 6-A typical ocean-return shape for a 2-meter wave  height.  are removed by individual waveform sample gain cor­ rection factors, derived from ground test data and re­ fined during the initial in-orbit evaluation phase.  Attitude Determination and Related Corrections  Spacecraft off-nadir attitude excursions cause the slope  in the plateau region of the ocean return to decrease. 
 18, 20, January, 1960.  17. Rhodes, D. 
 The sudden transfer of current from the switching tube Vltitothe condenser circuit results in theabrupt appearance ofavoltage drop across theresistor, thus providing thestep. The above circuits can beused toproduce a“micro-B” display by theexpedient ofgearing together the sweep-delay and the sector-width controls, and providing the proper normalization. Agiven normaliza. 
 R. C. Hansen, Microwave Scanning Antennas , New York Academic Press, New York, 1966; Los  Altos, CA: Peninsula Publishing, 1985. 
 22. pp. 305-3 18, April, 1961. 
 7hryef classijicario~t. The characteristic echo signal from a distributed target when observed  by a short pulse can be used to recognize one class of target from another.  ECCM. 
 R. Dickey, Jr. and M. 
 Also shown in Figure 2.90 is the curve for the conven - tional CA-CFAR,45 where all reference samples are equally weighted. If more than one  noise and/or clutter amplitude is used to update the clutter map content on each scan,  the value of Leff should be increased proportionally. It should also be noted that most  radars base their target detection on multiple hits using some form of video integra - tion, and that a clutter map loss based on the single-hit results of Figure 2.90 could be  much too large. 
 PRACTICE OF THE MICROWAVE MONOLITHIC INTEGRATED CIRCUIT --)#  THAT ENABLED MOST HIGH FREQUENCY PHASED ARRAYS TO BE REALIZED --)# USE IN 42 MODULE DESIGN HAS ENABLED BOLD NEW MODULE CONFIGURATIONS  AND HENCE PHASED ARRAY SYSTEMS  TO BE ENVISIONED "ECAUSE SOME OF THE MORE COMPLEX FUNCTIONS IN THE GENERIC 42 MODULE BLOCK DIAGRAM CAN BE FABRICATED BY USING --)# TECHNOLOGY  THE COM 
 Kurtz, L.A .. and R. S. 
 Any use is subject to the Terms of Use as given at the website. MTI Radar. 2.42  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 FIGURE 2.40  Velocity response curve: three-pulse binomial canceler, 51:62:53:61:58 pulse- interval ratio FIGURE 2.41   Velocity response curve: three-pulse binomial canceler, 11:16:13:17 pulse- interval ratio FIGURE  2.42 Velocity response curve: three-pulse binomial canceler, 53:58:55:59 pulse- interval ratio. This response curve continues to V/VB = 53 with no dips below 5 dB. 
 I am not  familiar with a rectangular or ‘square’ wave, but obvi-  ously these pulses and blips are a distorted form of some  truly geometric wave-form which has been applied to  a distorter.”” That is true, but what is the cause of the  meticulously arranged distortion? It is not, obviously,  the result of circuit fault, nor an uncontrollable effect.  We shall, in fact, discover on analysing many a radar  pulse-shaping circuit that no matter how many valves  are used the essential of the circuit is often the ‘inte-  grator’ or the ‘differentiator.’  FIG. 6  First consider a simple circuit diagram (Fig. 
 £       !  POLYPHASE FILTER IS A FILTER BANK THAT SPLITS AN INPUT SIGNAL INTO  $ SUB 
 A duct is a channel in which electromagnetic energy can  propagate over great ranges. To propagate energy within a duct, the angle made by  the electromagnetic system’s energy with the duct must be small, usually less than 1°.  Thicker ducts, in general, can support trapping for lower frequencies. 
 The  characteristics of materials suitable for microwave devices are given by Ince and Temme. 30  The physics or propagation of electromagnetic energy in ferrites is not easy to describe in  simple terms. 31 The magnetic permeability of a ferrite is anisotropic (that is, it depends on the  direction), and must be represented by a complex tensor rather than a scalar. 
 The radars also suffered from unreliable components, which often deteriorated over the course of a trial (especially the microwave mixer diodes [4,7]). In order to establish a comparative assessment of the sensitivity of these radars in the air, the CCDU attempted to develop the use of the detection rangesagainst known targets. On operational ﬂights the radars were assessed for service- ability soon after take-off against Lundy Island in the Bristol Channel, or the Isles of Scilly. 
 An elevation angle measurctnent can be made similar to that of the monopulse  radar described in Sec. 5.4. Two fan beams arc displaced ("squinted ") in elevation arigle and  tlie sum and difference patterns are obtained. 
 Applications using  chirp waveforms with large time-bandwidth products are typically less sensitive to  DDS spurious signals since the DDS spurious signals chirp at a different rate to that  of the wanted signal. The spurious signals are thus rejected during pulse compression.  In pulse doppler applications, spurious signals are of much greater concern; however,  their effects can be mitigated by ensuring that the DDS generates each waveform from  the same initial conditions. 
 RESPONSE BINOMIAL 
 DOMAIN RADAR THAT GIVES AN ADVANTAGE IN TERMS OF TRANSMITTER PEAK SIGNAL CAPABILITY COMPARED WITH THE IMPULSE '02 Ó£°ÈÊ  " 1 /" Ê/ 
 Any use is subject to the Terms of Use as given at the website. Radar Cross Section.  RADAR CROSS SECTION  14.56x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 14 Forward scattering  is a special case of bistatic scattering in which the bistatic angle is  180° whence the direction of interest is along the shadow zone behind the tar get. The shadow itself can be regarded as the sum of two fields of nearly equal strength  but 180 ° out of phase. 
 R. M. Lhermitte, Centimeter & Millimeter Wavelength Radars in Meteorology , Miami: Lhermitte  Publications, 2002. 
 Properties oftheambiguity diagram. Thefunction IX(TR,fd)12hasthefollowing properties: Maximum valueofIX(TR,fd)12=IX(O,0)12=(2£)2 (11.50) IX(-T R,-!d) 12=Ix(TR,fd) 12(11.51) Ix(TR,0)12=Ifu(t)u*(e+TR)dtl2 (11.52) Ix(O,fd) 12=Ifu2(t)el2J<fdldt12 (11.53) IfIx(TR,1d)12dTRdfd=(2£)2 Thefirstequation givenabove,Eq.(11.50),statesthatthemaximum valueoftheambigu­ ityfunction occursattheoriginanditsvalueis(2£)2,where£istheenergycontained inthe echosignal.Equation (11.51)isasymmetry relation. Equations (11.52)and(11.53)describe thebehavior oftheambiguity function onthetime-delay axisandthefrequency axis,respec­ tively.AlongtheTRaxisthefunction X(TR,fd)istheautocorrelation function ofthemodula­ tionu(t),andalongthe!daxisitisproportional tothespectrum ofu2(t).Equation (11.54) statesthatthetotalvolumeundertheambiguity function isaconstant equalto(2E)2. 
 Lee, and J. Vivekanandan, “A new high-altitude airborne milli - meter-wave radar for atmospheric research,” presented at Proc. Int. 
 The a posteriori probability can be written  [ 2 To l p(SN I y) = kp(SN) exp N~ t y(t)s1(t) dt ( 10.28) . DETECTION OF RADAR SIGNALS IN NOISE 379  where the first and third integrals of Eq. (10.27) are absorbed in the constant k. 
 millimeter waves was found to depend on the drop si~e distribhtion of the  pricipitation.102 Even though the rain rates were the same, the backscatter from rain contain-  ing drops 2 to 6 mm in diameter was approximately 10 dB greater than rain containing drops  1 mm in diameter or less. The amplitude fluctuations of the rain backscatter were approxi-  mated by a log-normal probability distribution over the range from 9.4 to 94 GHz and at rain  rates from 1 mm/h to 60 mm/h. The variance (and standard deviation) of the log-normal  distribution was independent of rain rate and decreased with increasing frequency. 
    Ê 
 80, pp. 389–406, 1999. 123. 
 FICATION INCLUDED THE NEED TO GIVE A CLEAR INDICATION OF COASTLINES RISING TO  FT AT  MILES  OF A  GROSS REGISTERED TON h)MPERIALv UNITS  VESSEL AT  MILES AND OF A  FT FISHING VESSEL AT  MILES 4HE MODERN PERFORMANCE REQUIREMENTS  SUMMARIZED IN 4ABLE   STILL USE THESE FIGURES BUT WITH PARAMETERS  EXCEPT RANGES  GIVEN IN EQUIVA 
 MIT WAVEFORM MUST HAVE A RELATIVELY LARGE BANDWIDTH TO INCREASE  THE NUMBER OF INDE 
 A widely used early radar dedicated to finding the height of a target in aug- mentation of a 2D surveillance set was the nodding antenna.* In this type of radar a horizontal fan beam, with a narrow elevation beamwidth, is mechanically scanned in elevation by rocking or "nodding" the entire antenna structure (Fig. 20.Id). As the radar beam traverses the target continuously transmitting pulses, the main-lobe target echoes that return are displayed to an operator by means of a range-height-indicator (RHI) type of display. 
 IJ Plot of Eq. (5.2). Apparent radar center t10 of two isotropic scatterers of relative amplitude a  and 1elativc phase shirt rx, separated by an angular extent Ov. 
 MODE AMPLIFIERS %ACH CLASS OF OPERATION FOR THE ANALOG MODES IS DEFINED BY THE MANNER IN WHICH THE TRANSISTOR IS BIASED EACH CLASS OF OPERATION  &)'52%   3OLID 
 Therefore  I H ( f) I = I r, ei2rr<i-llffT-k/NI I= I si~ [nN(.IT -~{N)J I  k · i == 1 sm [ n(.fT -k/ N)] (4.16)  By analogy to the discussion of the array antenna in Sec. 8.2, the peak response of the filter  occurs when the denominator of Eq. (4.16) is zero, or when n(.IT -k/N) = 0, n, 2n, .... 
 A simplified block diagram of a typ- ical rendezvous guidance subsystem is shown in Fig. 22.1. The radar search and acquisition mode is initiated by the guidance computer. 
 antenna aperture. and scan time is a constant. Eq. 
 71. R. J. 
 Magellan  SAR data were relayed from Venus to Earth via the DSN.  This major communication system imposed a working limit of about 270 kbit/s on  the SAR data telemetry. Whereas this may seem rather large, it is minuscule by  ch18.indd   50 12/19/07   5:15:10 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 20.3 for coherently combining received monopulse sum- and delta-channel (1,Q) target echo sam- ples from multiple-pulse transmissions. This technique is to be distinguished from the combining of in- dividual monopulse angle measurements from each of the multiple-pulse transmissions. (C) FIG. 
 The radar may  operate with a higher than normal false-alarm rate since targets can easily be con - firmed by additional dwells. Phase control allows beams to be widened, for example,  to reduce search time for the more elevated regions, where reduced ranges need less  antenna gain. A separate rotating surveillance radar system may be added for extra  coverage (at a second frequency) and to allow the 3D radar more time for tracking. 
 9Ê-* 
 Ê  1// 
 Ex ExEy ωtωt   Figure 11.3  Circularly polarized wave.     Figure 11.3 shows the trajectory of an electrical field vector of a circularly polarized wave  along the time axis, if a fix ed position is considered.   11.2.2  Polarization Scattering Matrix   If one describes an incident wave on an object with “i“ and the radiated wave at the receiver  with “r“ with the superposition of horizontal and vertical polarized electric fields according to  Equati on (11.3) the result is:  € Ehr Evr        =ShhShv SvhSvv        ⋅Ehi Evi             (11.4)  The matrix [S ] is called the Polarization Scattering Matrix. 
 Motion compensation is very important to achieve high resolution in SAR imagery. The phase errors that may be present on the focused image can be compensated through Inertial Measurement Unit (IMU) and Global Positioning System (GPS) side information. However, the need to measure and add such information to the ancillary data complicates the burden on any motion compensation system. 
 Digest , vol. 18, no. 2, pp. 
 7. Benning, C., and D. Hunt: Coefficients for Feed-Forward MTI Radar Filters, Proc. 
 Boyd. C'. R., Jr.: A Dual-Mode Latching Reciprocal Ferrite Phase Shifter. 
 Fox, P. Duggan, R. Gray, P. 
 C. Ghiglia, and P. A. 
  
 2.84  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 2 improvement factor restriction, as discussed in Section 2.11. Consequently, for the  limited IF dynamic range to have the desired effect on the output residues, the limit  level must be set 5 to 15 dB below the improvement factor limit of the linear system.  The net result is that some of the clutter suppression capability of the MTI radar must  be sacrificed in exchange for control of the output false-alarm rate. 
 PENSATED DOPPLER BEAM SHARPENING $"3  MODE )NVERSE 3!2 ! FAR MORE RELIABLE METHOD OF SHIP RECOGNITION IS INVERSE SYNTHETIC  APERTURE RADAR )3!2   4HE BASIC NOTION IS THAT THE  MOTION OF A RIGID OBJECT CAN BE  RESOLVED INTO A TRANSLATION AND ROTATION WITH RESPECT TO THE LINE OF SIGHT TO THE TARGET 4HE ROTATION GIVES RISE TO A DIFFERENTIAL RATE OF PHASE CHANGE ACROSS THE OBJECT 4HE PHASE HISTORY DIFFERENCES CAN BE MATCH FILTERED TO RESOLVE INDIVIDUAL SCATTERERS IN A RANGE CELL #ONCEPTUALLY  SUCH A MATCHED FILTER IS NO DIFFERENT THAN A FILT ER USED TO MATCH A PHASE 
 TO 
 Hibbs: A New Microwave Reflector, Narul Rrsrrrrcl~ Luh. Repf. 4141, 1953. 
 http://southport.jpl.nasa.gov/  5. http://www.astronautix.com/craft/almazt.htm  6. http://www.russianspaceweb.com/almazt.html  7. 
 It uses an identical leapfrog sequence. Both concepts relax the fractional beam scan requirements by either sampling or step- ping the beams in units of a beamwidth. Since they both process returns across two beamwidths before switching, the beam dwell time Th is approximately 2(A0/?)m/?/?/c and the stepping rate is Ti,"1. 
 Ifithas the correct value, the magnetron is operating atthe recommended point onitsperformance chart and is almost certainly putting r-fpower into the antenna line. Sparking ofthe magnetron orirregular modulator operation can beobserved. This meter reading isanover-all check onthe operation ofthe radar transmitter. 
 Mechanical errors in the lens  contour, IJbwever, contribute but once to the phase-front error. Although the theoretical  tolerance of a lens may be less than required of a reflector, in practice it might be more difficult  to achieve a given level of performance in a lens. A reflector can be readily supported mechan-  ically from the back. 
 8.14 is  where f = frequency of the electromagnetic signal  1 = length of line connecting adjacent elements (generally greater than the distance  between elenients)  1% - vclocity of propng;~tioti it1 the transnlissiot~ line  R = wavelengtli  For coriveriience of analysis, the velocity of propagation is taken to be equal to c, the velocity  of light. Ttiis is applicable to coaxial lines or similar structures which propagate the TEM mode.  If [tie bean1 is to point in a direction 00, the phase difference between elements should be  2n(tl/A) sin OO. 
 TERM STABILITY #OHERENCE !FTER &REQUENCY 3WITCHING  ,ONG RANGE RADARS OFTEN TRANSMIT A SERIES  OF PULSES BEFORE RECEIVING RETURNS FROM THE FIRST IN THE SEQUENCE 0ULSES MAY BE TRANSMITTED AT A NUMBER OF DIFFERENT OPERATING FREQUENCIES REQUIRING SWITCHING OF THE ,/ FREQUENCY BETWEEN PULSES )F TARGET RETURNS ARE PROCESSED COHERENTLY  THE PHASE OF THE ,/ SIGNAL MUST BE CONTROLLED SUCH THAT EACH TIME IT SWITCHES TO A PARTICULAR FREQUENCY  THE PHASE OF THE ,/ IS THE SAME PHASE THAT IT WOULD HAVE BEEN HAD NO FREQUEN CY SWITCHING OCCURRED  4HIS REQUIREMENT DRIVES THE ARCHITECTURE USED TO GENERATE ,/ FREQUENCIES 'ENERATING  ALL THE FREQUENCIES FROM A SINGLE REFERENCE FREQUENCY DOES NOT GUARANTEE PHASE COHER 
 1967.  97. Blackwell. 
 Kalmus clutter filter.59 This is a technique for extracting moving targets, such as a walking  person or a slowly moving vehicle, from land clutter whose doppler-frequency spectrum masks  that of the moving target. A moving target will produce a doppler-frequency shift that is either  at a lower or a higher frequency than the transmitted signal. Vegetation or trees will have a  back-and-forth motion due to the wind; hence, the doppler spectrum from such clutter will be  distributed on both sides of the transmitted frequency, especially if observed over a sufficie1;t  period of tirpe. 
 —Although limitations onsize, complex- ity,weight, and power consumption could besubordinated totherequire- ment forexcellence inradar performance, the designers were fully aware ofthe importance ofpractical limitations onthese characteristics. It was also well understood that without great care and effort toachieve the utmost insimplicity, dependability, convenient facilities fortest, and ease ofmaintenance, the equipment might fail togive satisfactory field service. Incomputations leading tothe choice ofsystem parameters the designers did not have the advantage ofmuch information that isnow available, yet inpractically every case their decisions were excellent. 
 DIMENSIONAL STRUCTURE OF VECTOR AIR MOTION  IN PRECIPITATION ! POINT SHOULD  BE MADE HERE REGARDING  THE USE OF TWO DOPPLER RADARS FOR MEASUREMENTS OF THREE 
 AP-22, pp. 742-745, November, 1974.  30. 
 1  CHAPTER ONE THENATURE OFRADAR 1.1INTRODUCTION Radarisanelectromagnetic systemforthedetection andlocation ofobjects.Itoperates by transmitting aparticular typeofwaveform, apulse-modulated sinewaveforexample, and detectsthenatureoftheechosignal.Radarisusedtoextendthecapability ofone'ssensesfor observing theenvironment, especially thesenseofvision.Thevalueofradarliesnotinbeinga substitute fortheeye,butindoingwhattheeyecannotdo...Radarcannotresolvedetailaswell astheeye,norisitcapableofrecognizing the"color"ofobjectstothedegreeofsophistication ofwhichtheeyeiscapable. However, radarcanbedesigned toseethrough thoseconditions impervious tonormalhumanvision,suchasdarkness, haze,fog,rairi,andsnow.Inaddition, radarhastheadvantage ofbeingabletomeasure thedistance orrangetotheobject.Thisis probably itsmostimportant attribute. Anelementary formofradarconsistsofatransmitting antenna emitting electromagnetic radiation generated byanoscillator ofsomesort,areceiving antenna, ~ndanenergy-detecting device,orreceiver. 
 VI for the lock-follow mode, as discussed later. Further aspects of the control and interpretation of the displays are discussed further with the switch unit, below. 3.3.5 Switch unit type 207 The switch unit type 207 is shown in ﬁgure 3.8and also in ﬁgure 3.7. 
 Critical parameters included PRF, range gate, burst length, burst  period, and spacecraft roll. The parameter files were prepared in advance, based on the  data collection geometry, and turned into commands to be generated by the radar map - ping sequencing software. The result was a set of about 1000 unique configurations,  each tied to specific segments of the orbit. 
 [ CrossRef ] 25. Zhang, Y.; Wu, H.a.; Sun, G. Deformation model of time series interferometric SAR techniques. 
 TO 
 The size ofthetube selected depends upon theparticular application. The relative resolution isfairly independent ofthesize, sothat from this standpoint alone there islittle value inincreasing the screen diameter. 486 1’IIERECh’I J’I.YG SI”.57’E.JI—I.VI) IC.4 TORS [SEC. 
 III [ 13] and discussed in chapter 3). Detection ranges of ASV Mk. VI reported for Lundy Island, typically 62 nmi at 2000 ft, and Isles of Scilly, typically 19 nmi at 1000 ft, were on average 40% greater than for ASV Mk. 
 It is assumed that data are recorded to an adequate resolution. Most antennas used  in surface penetrating applications have a limited low-frequency response and tend to  act as high-pass filters effectively differentiating the applied impulse. As the ground  acts as a low pass filter, the ground largely defines the bandwidth of reflected signal. 
 SIPATED POWER  ARE THE PARAMETERS THAT DETERMINE THE CELL SIZE AND ARRANGEMENT OF CELLS ON A CHIP 4HE ULTIMATE OPERATING JUNCTION TEMPERATURE OF THE TRANSISTOR IS LARGELY DEPENDENT ON THE TRANSIENT HEATING THAT WILL BE ENCOUNTERED AND THE LAYOUT AND AREA OF THE INDIVIDUAL CELLS &OR DEVICES THAT ARE DESIGNED TO OPERATE FOR LONG PULSES OR #7  AN INCREASE IN THE AVERAGE POWER CAPABILITY OF THE TRANSISTOR CAN BE ACHIEVED BY DIVIDING THE ACTIVE AREA OF A TRANSISTOR INTO SMALL  THERMALLY ISOLATED CELL AREAS 3INCE THE OVERALL THERMAL TIME CONSTANT FOR A TYPICAL POWER TRANSISTOR DIE ITSELF MAY  BE ON THE ORDER OF n §S  THE TRADEOFF BETWEEN PEAK AND AVERAGE POWER VERSUS  DEVICE SIZE CAN BE SIGNIFICANT FOR SOLID 
 -   . * 7ILLIS   "ISTATIC 2ADAR  ND %D  3ILVER 3PRING  -$ 4ECHNOLOGY 3ERVICE #ORP    #ORRECTED AND REPUBLISHED BY 2ALEIGH  .# 3CI4ECH 0UBLISHING  )NC     . * 7ILLIS AND ( $ 'RIFFITHS  EDS    !DVANCES IN "ISTATIC 2ADAR   2ALEIGH .# 3CI4ECH  0UBLISHING )NC     2 # (EIMILLER  * % "ELYEA  AND 0 ' 4OMLINSON  h$ISTRIBUTED ARRAY RADAR v  )%%% 4RANS   VOL !%3 
 The last entry pertains to phase-distortion echoes. The spectrum G(/) of the time function g(t) is assumed to have negligible energy outside the frequency interval -BII to +5/2, where B is the bandwidth in hertz. The transform pairs of Table 10.7 are interpreted as follows: Pair 1. 
 ITY CG  &OR EXAMPLE  &IGURE  SHOWS A ROLLING MOTION OF  o n THAT MIGHT BE  EXHIBITED BY A SHIP IN CALM SEAS 4HE ROLL MOTION MIGHT HAVE A PERIOD OF  SECONDS 4HE MOTION OF ALMOST ALL THE SCATTERERS ON A LARGE COMBATANT ARE MOVING IN ARCS OF CIRCLES PROJECTED AS SEGMENTS OF ELLIPSES TO A RADAR OBSERVER  &OR A RADAR OBSERVER THE  CHANGE IN RANGE  D2  ASSOCIATED WITH A ROLL MOVEMENT IS A FUNCTION OF THE HEIGHT   H  &)'52%  2ANGE PROFILE SHIP RECOGNITION . x°ÎÓ  2!$!2 (!.$"//+  OF THE SCATTERER ABOVE THE CENTER OF GRAVITY 4HE APPROXIMATE RANGE RATE FOR EACH SCAT 
 17.9. Comparison ofSynchronization Methods.-Not allthe syn- chronization methods described inthe previous sections have been used onactual radar relay systems although nearly allofthem have been setup and tested inthe laboratory. Because ofthe inadequacy oftesting in many ofthe cases, evaluations are difficult, but the following general statements can bemade. 
 2. W. L. 
 KM SWATHS 4HE .%Q R    IS n D" OR  BETTER AND MODE 
 Still another technique that is attractive when it can be applied, is to use a doppler  processor with a rejection notch wide enough to reject the clutter doppler even when the radar  platform is in motion. This is applicable only when the first blind speed is high (a low radar  frequency and/or high prf) and when the platform speed is low, as it would be with a ship-  mounted radar.  Generally, most clutter-lock MTI techniques do not adequately eliminate both stationary  and moving clutter when they appear simultaneously within the same range resolution cell. 
 F. E. Nathanson, Radar Design Principles, 2nd Ed. 
 TO 
 , AMS, Boston, 1972, pp. 216–221. 92. 
 Provision could be included for electronic beam steering using high-power phase shifters or transmit modules with low-power beam steering. On receive, each duplexer output is sent to its own digital receiver and adaptive processing module (APM), which provides a weighted undelayed signal that is com- bined with the outputs of the other adaptive processing modules to form an undelayed antenna beam. The weighted signal received on the previous pulse is com- bined with the corresponding outputs of the adaptive processing modules to form a de- layed antenna beam. 
 4.Aseries ofsymbols istelephoned totheFCC, giving thefollowing information: a.Identification oftrack asfriendly, enemy, orunknown. b.Number assigned totrack. c.Location ofplot. 
 Iftheazimuth and range ofatarget areknown from the first beam, the height can beinferred from thetime ofappearance ofthesame target inthesecond, or“slant” beam (see Fig. 4.1). This latter beam isassociated with acompletely. 
 ATE FOR THE CASE OF A WEAK TARGET ADJACENT TO A STRONG TARGET  AND THERE IS NO ACCEPTED  DEFINITION OF RESOLUTION FOR THE CASE OF UNEQUAL SIZE TARGETS 0LAN 2ESOLUTION  4HE PLAN  PLAN IS DEFINED AS A PLANE NORMAL TO THE DIRECTION  OF PROPAGATION  RESOLUTION OF A '02 SYSTEM IS IMPORTANT WHEN LOCALIZED TARGETS ARE SOUGHT AND WHEN THERE IS A NEED TO DISTINGUISH BETWEEN MORE THAN ONE AT THE SAME DEPTH 7HERE THE REQUIREMENT IS FOR LOCATION ACCURACY  WHICH IS PRIMARILY A TOPO 
 Hence snow or  ottier fr07cn precipitation is not readily deposited.  .I-lle first large radornes (50-ft diameter or more) for gr-outid-based radar antennas ap-  peared stiortly afier World War 11. They were constructed of a strong, flexible rubberized  airtiglit material and were supported by air pressure from witIlin.'O3 Since tlie material of  air-supported radomes can be relatively thin and uniform, they approximate the electrically  ideal tliiu sliell which provides good electrical properties. 
 vol. 128, "Etfective Utilization of Optics in Radar  Systems," pp. 155 - 164. 
 Schleher, D. C.: Radar Detection in Weibull Clutter, IEEE Trans., vol. AES-12, pp. 
 51.Hall,W.M.:Antenna Beam-Shape FactorinScanning Radars,IEEETrans.,vol.AES-4.pp.402-409, May,1968.. 52.Trunk,G.V.:Detection ResultsforScanning RadarsEmploying Feedback Integration, IEEETrans., vol.AES-6,pp.522-527, July,1970. 53.Davenport, W.B.,Jr.:Signal-to-noise RatiosinBand-pass Limiters, J.Appl.Phys.,vol.24, pp.720-727, June,1951 54.Manasse, R.,R.Price,andR.M.Lerner:LossofSignalDetectability inBand-pass Limiters, IRE Trans.,vol.1T-4,pp.34-38,March.1958. 
 ThePulse-jorming Network.—One ofthe possible lumped-constant networks having electrical properties essentially equal tothose ofa transmission line isgiven inFig. 10.37, with thevalues ofLand Cneces- sary foraline ofgiven impedance and pulse length. Iftheinductance is constructed bywinding auniform helix onaninsulating cylinder, the ratio ofcoil length tocoil diameter should bethat shown inFig. 
 In some applications of CW radar it is of interest to know whet her  the target is approaching or receding. This might be determined with separate filters located  on either side of the intermediate frequency. If the echo-signal frequency lies below the carrier,  the target is receding; if the echo frequency is greater than the carrier, the target is approaching  (Fig. 
 In an FPGA, we could assign 16 multipliers and 16 accumulators to  the task, and the filter could be performed in one clock cycle. ch25.indd   36 12/20/07   1:40:45 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 Bair, G. L., and G. E. 
 As is evident, the aspect angle of the  target clear of sidelobe clutter is always forward of the beam aspect. Ambiguities and PRF Selection.  Pulse doppler radars are ambiguous in range  and possibly doppler. 
 I. Skolnik (ed.), McGraw-Hill Book Co., Ncw  York, 1970, sec. 17.20. 
 The complete exploitation of polarization requires the measurement of phase, as well as amplitude of the echo signal at two orthogonal polarizations and a cross-polarization component. Such measurements (which define the polarization matrix) should allow in principle the recognition of one class of target from another, but in practice it is not easy to do. One characteristic of target shape is its surface roughness. 
 TO 
 4ARGET )NDICATOR -4)  "LOCK $IAGRAM  ! MORE COMPLETE BLOCK DIA 
 Pis the AR model order, and [ ·]Hdenotes the conjugate transpose. In order to obtain the AR model coefficient a(k), the criterion that to minimize the sum of the forward and backward prediction errors in each iterative procedure is utilized [ 20,22], which is given as: EP=N⎭summationtext n=P+1⎭vextendsingle⎭vextendsingle⎭vextendsingleef(τ,n)⎭vextendsingle⎭vextendsingle⎭vextendsingle2+⎭vextendsingle⎭vextendsingle⎭vextendsingleeb(τ,n)⎭vextendsingle⎭vextendsingle⎭vextendsingle2 2(23) To solve Equation (23), the Levinson recursion algorithm [ 24–26] is used, which can be solved as follows: aP(i)=aP−1(i)+ aP(P)aH P−1(P−i),i=1, 2,...,P−1 (24) By substituting Equation (24) into Equation (19) and Equation (20), respectively, we can have: ef P(τ,n)=ef P−1(τ,n)+aP(p)eb P−1(τ,n−1) (25) eb P(τ,n)=eb P−1(τ,n−1)+aH P(p)ef P−1(τ,n) (26) 75. Sensors 2019 ,19, 1920 Since the forward and backward predictions are known in each iteration, then the AR coe ﬃcients ap(p) can be calculated as: ap(p)=−2N⎭summationtext n=P+1ef p−1(τ,n)⎭parenleftbigg eb p−1(τ,n−1)⎭parenrightbiggH N⎭summationtext n=P+1⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingleef p−1(τ,n)⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle2 +⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingleeb p−1(τ,n−1)⎭vextendsingle⎭vextendsingle⎭vextendsingle⎭vextendsingle2(27) Based on the calculated AR coe ﬃcients ap(p)„ the forward and the backward signals (i.e., sf(τ,n) and sb(τ,n–p) and can be calculated as: sf(τ,n) =−P⎭summationtext i=1aP(i)·K⎭summationtext k=1σk·rect⎭parenleftbigg (n−i)·tr Ta⎭parenrightbigg ·sin c⎭bracketleftbigg B⎭parenleftbigg τ−2R((n−i)tr) c⎭parenrightbigg⎭bracketrightbigg exp⎭parenleftbigg −j4πR((n−i)tr) λ⎭parenrightbigg (28) sb(τ,n−P) =−P⎭summationtext i=1aH P(i)·K⎭summationtext k=1σk·rect⎭parenleftbigg (n−P+i)·tr Ta⎭parenrightbigg ·sin c⎭bracketleftbigg B⎭parenleftbigg τ−2R((n−P+i)tr) c⎭parenrightbigg⎭bracketrightbigg exp⎭parenleftbigg −j4πR((n−P+i)tr) λ⎭parenrightbigg (29) where Kis the number of scatters in one range cell. 
 n,z . ,I,  tl ." sin [n(d/A)(sin 4 - sin i)] En(&) = - 1 E(S) d(sin <)  2. Cm n(d/A)(sin 4 - sin {) d(sin €) dr (7.24)  where E,($) is tlie Fourier-integral pattern which approximates the desired pattern E(4) when  A(=) is rcstrictcd to a finite apci ture of diinensioti d. 
 POLARIZATION TECHNIQUES SHOW SIGNIFICANT IMPROVEMENTS IN ACCU 
 (14.29) for k7;, F, in Eq. (2.54). the radar equation for a searchlighting  or tr:lcki~~g radar, yields  wlicrc r,, = I!;/, = ir~tcgratio~i tirt~c. 
 236  Fences, radar. 175. 497 -498  Ferrimagnetic phase shifters, 291-297  Ferrite limiter. 
 TIALLY AVAILABLE  AND THE FIRST MONOPULSE SYSTEMS WERE COMPLEX  AND RESULTED IN CUM 
 19.9. Active seekers, since they use a single antenna both to transmit and to re- ceive, cannot use CW because of the very limited isolation achievable. Noncoherent pulse or coherent PD waveforms have been employed, and either the central-line processing or the range-gated approach can be used for coherent operation. 
 With a single short pulse, the doppler frequency shift will be small  compared to the receiver bandwidth so that only one matched-filter is needed for detec­ tion, rather than a bank of matched filters with each filter tuned for a different doppler  shift.  A short-pulse radar is not without its disadvantages. It requires large bandwidth with the  possibility for interference to other users of the band. 
 SHIFT CAPABILITY AT EVERY ELEMENT TO STEER A BEAM  C  . 
 DEFINED SIGNAL  AND DATA PROCESSING  FIRST INTRODUCED IN THE MID Sn 3OFTWARE PROGRAMMABILITY  ALLOWS MANY RADAR SYSTEM MODES TO BE PERFORMED USING THE SAME 2& HARDWARE )N ADDITION  MODERN NAVIGATION AIDS WORK SO WELL THAT EACH RADAR MODE IS DEFINED BY ITS EARTH SITUATION 
 POWER REMOTE SENSING RADARS TO DETECT SHIPS AT OVER 
 15.5 SUMMARY AND CONCLUSIONS In the early days of radar, the importance of knowing the sea clutter environment led  to many experiments under a variety of conditions. Variations in quality and complete - ness of ground truth, calibration of the equipment, and the experimenter’s experi - ence led to results that often showed considerable inconsistency and suggested clutter  behavior that was sometimes more a function of the vagaries of the experiment than of  the physics of the clutter. As data of increasingly better quality accumulated, it might  have been expected that the behavior of sea clutter would be established with increas - ing confidence. 
 When plots were sparse, the accuracy was excellent, and the on]yobjection tothe system was itsunavoidable time lag inreporting. Under conditions ofhigh aircraft density, the system broke down, and itwas commonplace tocease reporting incertain areas where thedensity was sohigh that filtering was impossible. Inspite ofthese handicaps, very considerable success attended the use ofthis system inthe Battle ofBritain and thereafter. 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Pulse Doppler Radar.  PULSE DOPPLER RADAR  4.296x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 4 under the same gating conditions that will be used in the radar system. 
 Wlieri the temperature inversion occurs below the altitude at which clouds are  fbrr~ied, a l~azc Ii~ycr it1 the air below tl~e ternperature inversion can be observed. The altitude  of [lie tradewi~id duct varies from hundreds of meters at the eastern part of the tropical oceans  to tiiousands of meters at the western end. Thus, the height gradually rises in going from east  to west. 
 TIVELY TURBULENT AIR  RANGE FROM ABOUT  (Z FOR SMALL AIRCRAFT TO ABOUT  (Z FOR LARGER AIRCRAFT " CHANGES IN PROPORTION TO RADAR  FREQUENCY PROVIDED THAT THE TAR GET SPAN IS AT  LEAST A FEW WAVELENGTHS !GAIN  LONG TIME SAMPLES ARE NECESSARY TO OBTAIN A RELATIVELY SMOOTH SPECTRUM FROM MEASURED DATA &OR THE ABOVE VALUES OF  "  ABOUT  MINUTES OF  DATA WAS NECESSARY TO REACH ESSENTIALLY THE LONG 
 Radarfalse-alarm probabilities arerarelygreater than10-4.Lowvaluesoffalse-alarm probability withtheIdealObserver requireextremely largevaluesofdetection probabilities. Forexample, afalse-alarm probability of10-5corre­ spondstoadetection probability of0.99998. Thustheprivilege ofminimizing thetotalerror seemstoresultinoverdetecting thetarget.Therefore, fromapractical pointofview,theIdeal Observer islessefficient thantheNeyman-Pearson Observer formostradarapplications. 
 ( Boresight  is the electrical  axis of the antenna or the angular location of a signal source within the antenna beam  at which the angle-error-detector outputs go to zero.) Some of the typical monopulse feeds are described to show the basic relations and  tradeoffs involved in the various performance factors and how the more important  factors can be optimized by a feed configuration but at the price of lower performance  in other areas.4 Many new techniques have been added since the original four-horn  square feed in order to provide good or excellent performance in all desired feed char - acteristics in a well-designed monopulse radar. The original four-horn square monopulse feed is inefficient because the optimum  feed size aperture for the difference signals is approximately twice the optimum size  for the sum signal.5 Consequently, an intermediate size is typically used with a signifi - cant compromise for both sum and difference signals. The optimum four-horn square  feed, which is subject to this compromise, described in Sherman,1 is based on mini - mizing the angle error caused by receiver thermal noise. 
 Figure 7.2 shows an example for this.    CW power Oscillator fIF±  fDfo±  fD fDProcessor & DisplayDoppler Amplifier IFAfofIF xfo OFFSET L.O. Targe t   Figure 7.2  Block circuit diagram of Radar with IF. 
 68. F. V . 
 ÓÈ°£È  2!$!2 (!.$"//+  7HILE WAVEGUIDE MODELS ARE MOST USEFUL FOR CONDITIONS WHERE THE VERTICAL REFRACTIV 
   -ARCH   2 6IGNERI ET AL  h! GRAPHICAL METHOD FOR THE DETERMINATION OF EQUIVALENT NOISE BANDWIDTH v  -ICROWAVE *OURNAL  VOL   PP n  *UNE   $ 3TEINBERG  h#HAPTERS v #HAPSn IN  -ODERN 2ADAR !NALYSIS  %VALUATION  AND 3YSTEM  $ESIGN  2 3 "ERKOWITZ ED   .EW 9ORK  .9 *OHN 7ILEY AND 3ONS    * 2 +LAUDER  h4HE THEORY AND DESIGN OF CHIRP RADARS v  "ELL  3YSTEM  4ECHNICAL  *OURNAL     VOL 888)8  NO   PP n  *ULY   7 2ICE AND + ( 7U  h1UADRATURE SAMPLING WITH HIGH DYNAMIC RANGE v  )%%% 4RANS !EROSPACE  AND %LECTRONIC 3YSTEMS  VOL !%3 
 9   . www.tektronix.com/radar  3    Figure 1: A Weather Radar D isplay   What is Radar ?  Radar (RAdio Detection And Ranging) is actually a fairly  simple  process  of bouncing radio waves off object s and  looking at the reflections to determining presence, size,  distance, position and speed.   Typically, radars illuminate their targets with an RF pulse and  then listen for the return echo. 
 HORN FEED WITH COUPLING TO BOTH LINEAR 
 "Ring echoes " have been observed on  PPI displays that start at a point and form a rapidly expanding ring.''' After one ring grows  to a diameter of several miles, a second ring forms. Other rings can form similarly. They  expand at velocities ranging from 20 to 30 knots and can attain diameters of 30 km or more. 
 Polarimetry . For any given polarization of the transmitted wave, the reflectivity  process in general will give rise to a diversity of polarizations in the backscattered  wave. To observe these, the radar must be dual-polarized. 
 and V. A. Mikenas: Advances in High Power, S-Band  Trapatt-Diode Amplifier Design, l\ficrowave J., vol. 
 Sheen, D.M.; McMarkin, D.L. Three-dimensional radar imaging techniques and systems for near-ﬁeld applications. In Proceedings of the SPIE Defense + Security, Baltimore, MD, USA, 12 May 2016. 
 In this  fashion, the beam is more efficiently formed in space and one avoids the losses than  can accumulate in corporate combining. The transmit/receive (T/R) module, regard - less of complexity, has five fundamental functions: (1) to provide gain and power  output in the transmit mode, (2) to provide gain and low-noise figure in the receive  mode, (3) to switch between transmit and receive states, (4) to provide phase shift for  beam steering for both transmit and receive paths, and (5) to provide self-protection  for the low-noise amplifier. The first T/R module was developed by Texas Instruments in the mid-1960s as  part of the Molecular Electronics for Radar Applications (MERA) program initi - ated by the U.S. 
 TION ARE  AT BEST  GUIDELINES FOR GAUGING OTHER APPROXIMATE  METHODS OF COMPUTING SCATTERED FIELDS !N ALTERNATIVE APPROACH IS THE SOLUTION OF THE INTEGRAL EQUATIONS GOVERNING THE DIS 
 (c) Block diagram of the filter for generating the  transmitted waveform of (a) with the input on the left. The same tapped delay line can be used as the  receiver matched filter by inserting the received echo at the opposite end (the right-hand side of the delay  line in this illustration).  428INTRODUCTION TORADAR SYSTEMS Phase-coded pulsecompression.16.29.30.38 Inthisformofpulsecompression, alongpulseof duration TisdividedintoNsubpulses eachofwidthr.Thephaseofeachsubpulse ischosento beeither0or1tradians.1f -theselection ofthe0,1tphaseismadeatrandom, thewaveform approximates anoise-modulated signalwithathumbtack ambiguity function, asin Fig.11.13c.Theoutputofthematched filterwillbeaspikeofwidthrwithanamplitude N timesgreaterthanthatofthelongpulse.Thepulse-compression ratioisN=Tlr=BT,where B=I/r=bandwidth. 
 SURFACE HEIGHT ACCURACY OVER LARGER SPATIAL SCALES AND LONG TIME SCALES  THEN A HIGHER ALTITUDE ORBIT HAVING A RELATIVELY MODERATE PROGRADE INCLINATION  AND RELATIVELY SHORT NON 
 Imaging fan results; ( a1) FFT algorithm with 32 pulses; ( b1) Relax algorithm with 32 pulses; (c1) APES algorithm with 32 pulses; ( d1) KA-DBS algorithm with 32 pulses; ( a2) FFT algorithm with 64 pulses; ( b2) Relax algorithm with 64 pulses; ( c2) APES algorithm with 64 pulses; ( d2) KA-DBS algorithm with 64 pulses.    (a1) ( b1)     (c1) ( d1)  Figure 11. Cont . 
 If it is not known that the roles of the meters are  ,,.,., -· Tronsm/tted signal // Received siqnol  ~/ ~ '"",,  ~~~~~~..,....:,...,_~----.~~~~...:,,.....~~~--,,:.""-~  (a)  Figure 3.12 Frequency-time relation­ ships in FM-CW radar when the  received signal is shifted in frequency  by the doppler effect {a) Transmitted  {solid curve) and echo (dashed curve)  frequencies; (b) beat frequency. 84 INTRODUCTION TO RADAR SYSTEMS  reversed because of a change in the inequality sign between/~ and/~, an incorrect interpreta­ tion of the measurements may result.  When more than one target is present within the view of the radar, lhe mixer output will  contain more than one difference frequency. 
 GYRATION OF THE  DISTRIBUTION OF REFLECTING AREAS OF THE TARGET &)'52%     !MPLITUDE PROBABILITY DISTRIBUTION OF ANGLE SCINTILLATION MEASURED ON A SMALL  TWO 
 In many radar systems we use both electrostatic  and magnetic deflection at once, and simultaneously we  control or modulate the beam by a varying voltage on the  tube grid. The electrons striving to go on their un-  checked path at 15,000 miles a second are thus given  quite a task! Magnetic tubes usually have a rather long  E  . 66 HOW RADAR WORKS  ‘neck’? in which all the electrodes are placed, leaving  still a circular space around which the magnetic poles  can-be placed. 
 FILLER FOR MONOSTATIC AIR SURVEILLANCE RADARS 0REDICTED DETECTION AND TRACKING RANGES OF  KM ON A  M  TARGET HAVE BEEN  DEMONSTRATED IN REAL TIME WITH $ TRACKING ERRORS GENERALLY LESS THAN  M #OARSE TARGET ELEVATION HAS ALSO BEEN MEASURED $OPPLER DATA HAS BEEN USED TO RESOLVE  GHOSTS   IE  FALSE DETECTIONS THAT INEVITABLY ARISE WHEN USING MULTILATERATION ON UNAUGMENTED TARGETS  0"2S HAVE USED SATELLITE COMMUNICATION TRANSMITTERS TO MEASURE CHARACTERISTICS  OF MOON AND PLANETARY SURFACES AND ATMOSPHERES IN BOTH THE TRANSMITTER 
 2018 , 1–14. [ CrossRef ] 3. Hanssen, R.F. 
 The improvement factor for a DFT filter31 is given by IN-I 1 2X2 '<*) = ^r^i — <17-4> E 2X A>» exP (-2 WII - «) ac 7f} cos [2irX(n - m)IN] n=0 m=0 where A1 = DFT weight, O < i < N - 1 N = number of points in DFT <TC = standard deviation of clutter spectrum K = filter number (K = O is dc filter) T = interpulse period Here, the improvement factor for a filter (versus the more common definition applied to a delay-line canceler) is defined as the ratio of the total clutter power input to the filter to the clutter residue in that filter. Expressed another way, the improvement factor is the ratio of the clutter power out of a filter if it were cen- tered over the clutter, and the clutter width reduced to zero, to the power out of the filter in actual operation.32'33 Figure 17.13 shows the improvement factor of a 256-point, Dolph-Chebyshev weighted FFT as a function of the clutter width for various filter numbers in the filter bank. If the main beam is pointed below the horizon and is greater than a beam width from 0° azimuth, the 6 dB clutter width due to platform motion A/is 2VRA/=— 6B sin ifo (17.5)A. 
 CASE DETERMINISTIC MANEUVER VICE A RANDOM ONE4!",%  #OMPARISON OF -ETHODS OF 4UNING +ALMAN &ILTER FOR 0RACTICAL 2ADAR 4RACKING 0ROBLEMS #ONTINUED   . 
 The input signal y(t) is multiplied by a delayed replica of the  transmitted !ignal s(r -T,), and the product is passed through a low-pass filter to perform  the integration. The cross-correlation receiver of Fig. 10.3 tests for the presence of a target at  only a single time delay T,. 
 Any use is subject to the Terms of Use as given at the website. Multifunctional Radar Systems for Fighter Aircraft. 
 RANGE 
 (ILL    PP n   * 9 . #HO ET AL  h2ANGE 
 ISOTROPIC   'K  E  P FOR  
 Elphick, B. L., M. J. 
 RANGE RADARS !DMITTEDLY  THIS  IS SOMEWHAT ARBITRARY  BUT THE CHOICE OF  n IS BASED UPON SEVERAL DECADES OF EXPERI 
 Horton and  J. F. Coales made noteworthy contributions to radar  which eventually played an important part in radar-  directed guns which sank the Bismarck and the Scharn-  korst. 
 On the  other hand, random errors differ from one antenna to the next even though they be of the same  design and constructed similarly. Therefore the effect of random errors on the antenna pattern  can be discussed only in terms of the average performance of many such antennas or in terms  of statistics.  The effect of errors on the radiation pattern has long bee? recognized by the practical  antenna designer. 
  n E E      n n E 
 PULSE  DWELL 
 FIG. 16.23 Block diagram of a digital space-time adaptive array radar. for space-time adaptive array processing. 
 lllcenrarional Con( on Radar----Presenc and  l-11r1ire. Oct. 23 25. 
 A saturation detector  detects whether any of the 10 pulses within a processing interval saturates the AID converter  and if it does, the entire 10 pulses are discarded.  Tile output of the MTD is a hit report which contains the azimuth, range, and amplitude  of tl~c target rctilrrl as well as the filter number and prf. On a particular scan, a large aircraft  niiglit be reported from more than one doppler filter, from several coherent processing inter-  vals. 
 16.14. The’ Transmitter and ItsModulator.—Thc transmitter stability requirements, specified inSec. 16.5, canbemet bymagnetrons ofexisting design. 
 R. Ward: RAMP's New Primary Surveillance Radar, Microwave /., p. 105, December 1984. 
 7.) If the noise samples are dependent in time or have a non-Rayleigh density such as the chi-square density or log-normal density, it is necessary to estimate two parameters and the adaptive detector is more complicated. Usually several pulses are integrated so that one can assume the integrated output has a gaussian probability density. Then the two parameters that must be estimated are theREFERENCECELLS SQUARE-LAW DETECTORMOVINGWINDOW . 
 (Available from DTI Internet site www.divtecs.com.) 52. M. Gaudreau et al., “High performance, solid-state high voltage radar modulators,” presented at  2005 Pulsed Power Conference. 
 (a) Entropy change of the two sub-images during iteration. ( b) IC values change of the two sub-images during iteration. 288. 
 A change in phase is obtained by a change of the applied magnetic field that  results from a change of the current passing through the coil. This is called an analog phase  shifter since a continuous phase change is obtained as a function of the current through the  solenoid. It is a reciprocal device in that the phase shift is the same for both directions of  propagation. 
 VATURE FOR THE %ARTH 4HE REFRACTIVITY GRADIENT FOR WHICH THE TWO RADII OF CURVATURE ARE EQUAL IS REFERRED TO AS THE  CRITICAL GRADIENT !T THE CRITICAL GRADIENT  THE WAVE WILL PROPA 
 Radar Conf., pp. 380-386, 1980. 47. 
 NOISE RATIO  FOR USER 
 TheJeceiver ofthesimpleCWradarofFig.3.2isinsome respectsanalogous toasuperheterodyne receiver. Receivers ofthistypearecalledhomodyne receivers, orsuperheterodyne receivers withzeroIF.14Thefunction ofthelocaloscillator is replaced bytheleakagesignaHrom thetransmitter. Suchareceiverissimplerthanonewitha moreconventional intermediate frequericy sincenoIFamplifier orlocaloscillator isrequired. 
 ATING MULTIPLE WAVEFORMS SIMULTANEOUSLY FROM THE SAME TRANSMITTING FACILITY !ND SIXTH  FOR HIGH POWER (& RADARS  THE ADDITIONAL POWER DENSITY ASSOCIATED WITH PULSE  WAVEFORMS IN THE IONOSPHERE MAY  IN PRINCIPLE  CAUSE SELF 
 To facilitate multifunction use, the RF components are installed in a number of plug-in  rnodules, S by 8 by 12 feet in size, which mount directly behind the Cassegrain reflector.  The presence of the subreflector in front of the main reflector in the Cassegrain  configuration causes aperture blocking. Part of the energy is removed, resulting in a reduction  of the main-beam gain and an increase in the sidelobes. 
 Eq. (7.31) becomes  (7.32)  From Eq. (7.31 ), the reduction in gain on axis can be written as  Beam direction  r  ---¢-~ (7.33)  Figure 7.28 Coordinate system defining the angles 0, </J of Eq. 
 The short-slot hybrid has the property that each time the energy passes through  the slot in either direction, its phase is advanced 90". Therefore, the energy must travel as  indicated by the solid lines. Any energy which leaks through the TR tubes (shown by the  dashed lines) is directed to the arm with the matched dummy load and not to the receiver, In  addition to the attenuation provided by the TR tubes, the hybrid junctions provide an addi-  tional 20 to 30 dB of isolation. 
 The rotating 15-ft by 30-ft antenna structure houses 54 row transceivers, each of which drives an RF distribution board that feeds one row of 24 dipole antenna elements. The peak power output capability of the system is 54 kW at an average duty cycle of 18 percent. The row electronics circuitry feeds each of 54 row feed networks. 
 Z. Peebles. Jr.: Conopulse Radar, IEEE Trans. 
 Moyer, Technology Service Corp .) ch23.indd   16 12/20/07   2:21:28 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Bistatic Radar. 
 OF 
 Since amajor source ofpower waste inthe circuit isinthecathode-heating required tosustain the desired emission, itiscustomary touseoxide-cathode emitters wherever possible. Unfor- tunately, oxide-cathode tubes are not easily adaptable tohigh anode voltages because ofthe phenomenon ofcathode sparking. With proper. 
 is missing for a  sufficient number of consecutive scans, the track is terminated. Although the criterion for  terminating a track depends on the application, one example suggests that when three target  reports are used to establish a track, five consecutive misses is a suitable criterion for  termination. 8 2  One of the corollary advantages of ADT is that it effects a bandwidth reduction in the  output of a radar so as to allow the radar data to be transmi!ted to another location via  narrowband phone lines rather than wideband microwave links. 
 25.Whetton, C.P.:Industrial andScientific Applications ofDoppler Radar,Microwat't' 1.,vol.18, pp.39-42,November, 1975. 26.Easton, R.L.,and1. 1.Fleming: TheNavySpaceSurveillance System,Proc.IRE.vol.48,pp.663-669. 
 Evidently weneed some measure ofthe amount ofpower reflected bythe target. For this purpose wedefine the scattering cross section ofthetarget uasfollows: u(dimensions ofanarea) istobe4Ttimes theratio ofthepower perunit solid angle scattered back toward thetransmitter, tothe power density (power per unit area) inthe wave incident onthe target. Inother words, ifatthe target the power incident onanarea uplaced normal tothebeam were tobescattered uniformly inalldirections, theintensity ofthesignal received back attheradar setwould bejust what itisinthe case ofthe actual target. 
 Parizzi, P. Pasquali, C. Prati, and F. 
 Althougll the resolution of an HF radar is poorer in range and angle than that of  tnicrowave radar, its resolution in the doppler-frequency domain is quite good. Targets not  resolvable in range or angle can be readily resolved in doppler. After targets are resolved in  doppler, measurements in range and angle can be made to a greater accuracy than given by the  noniinal resolution in those coordinates. 
 Jones, and J. W. Johnson, “The Seasat-A satellite scat - terometer,” IEEE Journal of Oceanic Engineering , vol. 
 DAY REPEAT CYCLE PREFERRED OPERATIONS ARE DURING THE HOURS OF DARKNESS IN THE ASCENDING PASSES FOR MOST MODES  EXCEPTING LOWER DATA 
 December. 1957. 47.McMahon. 
 The sampled range interval is selected so that clutter is likely  to be the dominant signal. From this measurement of clutter doppler within the sampled range  interval, compensation is made over the entire range of observation either by changing the  reference signal from the coho or by adjusting the phase shifter inserted in one of the arms of  the delay-line canceler. Generally, the average doppler frequency or phase shift is obtained by  averaging the sampled range-interval over a number of pulse repetition periods. 
 The upsampling is accomplished by  zero insertion as described in the previous section, “Interpolation Filters.” Note that the  processing only consists of delays and adds. Figure 25.37 a shows the sin( x)/x frequency response of a single-stage CIC deci - mator, where R = D = 8. The desired passband is the lightly shaded area centered at   0 Hz with bandwidth BW. 
 (2) When taking sequential doppler  measurements, the target’s velocity vector remains constant64 or predictable.62 For  example, many doppler-only, precision range instrumentation systems were developed  in the U.S. after WWII.9 Both beacon-aided and skin-track systems were developed.  All required initialization of the track data, which was conveniently provided by the  target’s launch coordinates. 
 However, the field strength at, and just within, the geometrical hori~on decreases with decreas-  ing frequency.  It is concluded that if low-altitude radar coverage is desired beyond the geometrical  horizon in the diffraction region, the frequency should be as low as possible. If, on the other  hand, low-altitude coverage is to be optimized within the interference region and if there is no  concern for coverage beyond the horizon, the radar frequency should be as high as possible. 
 It is worth noting that in case Δfdiﬀers from zero (i.e., has a ﬁnite value) an unambiguous time interval Δτof the ISAR compressed signal registration has to be deﬁned (i.e., Δτ=1/Δf). In a discrete time-frequency grid of the asteroid’s signal registration, the range compression can be expressed as ˆS(k,p)=R−1⎭summationdisplay r=0⎭summationdisplay g∈G⎭tildewideag[ˆtg(p)]·exp⎭parenleftBig j·2π·fr·ˆtg(p)⎭parenrightBig (10) 111. Sensors 2019 ,19, 3344 Figure 5. 
 TIONS OF )-/ RADAR PERFORMANCE STANDARDS )N ADDITION  IT WAS AGREED THAT THE )%# STANDARDS WOULD INCLUDE TEST PROCEDURES   WHICH COULD BE USED BY  NATIONAL MARITIME  ADMINISTRATIONS SUCH AS THE #OAST 'UARD IN THE 5NITED 3TATES OF !MERICA  TO TEST FOR CONFORMANCE OF SPECIFIC DESIGNS BY MANUFACTURERS TO )-/ AND )45 REQUIREMENTS 4ODAY  VIRTUALLY ALL NATIONAL ADMINISTRATIONS USE )%# STANDARDS TO ASSESS RADAR AND MOST OTHER )-/ 
 Consequently,  the high precision tracking radars with typically 4000 to 8000 phase shifters and four  or more phase shift bits have small resultant electrical axis error steps on the order of  0.1 milliradians or less. The electrical axis errors are essentially random and can be  further reduced by averaging. Intentional dither of phase steps may be introduced to  aid in averaging. 
 For ex- ample, with two targets present at different dopplers, the two frequencies ob- served during the FM period cannot be unambiguously paired with the two frequencies observed during the no-FM period. Thus, typical high-PRF range- while-search radars use a three-segment scheme in which there are no- . FM, FM-iip, and FM-down segments. 
 15. Goetz, L. P., and J. 
 L. Posner, and J. P. 
 '(Z DOPPLER RADAR FOR CLOUD OBSERVATIONS v  * !TMOS /CEAN 4ECHNOL    VOL   PP n    * ( 2ICHTER  h(IGH 
 The voltage across thecombination isthen jl(A +Bsin0)+~@ +Bcoso), where fland fzrepresent theaudi~frequency input voltages and Aand B areconstants. Since Aisgreater than B,theamplitude terms arealways positive. This voltage ismixed with aconstant-amplitude a-fsignal of frequency fj(which isused forAGC atthereceiver), and thecombination isused tomodulate asubcarrier ofsomewhat higher frequency than the maximum required forvideo signals. 
 (o)Oscillator intune with i-fsignals. (~)Oscillator detuned.retain the video amplifier and make sure that the coherent oscillator is always well tuned tothei-fsignals. Noserious loss insignal-to-noise will occur ifthere isless than one-quarter ofabeat cycle ineach pulse. 
 F. Gatelli, A. Guarnieri, F. 
 J. Sullivan, Radar Foundations for Imaging and Advanced Concepts , Raleigh, NC: SciTech,  2004; previously published as Microwave Radar: Imaging and Advanced Concepts , Norwood,  MA: Artech House, 2000.  2. 
          
 126- 133.  65. Johnson, M. 
 3 2 4 1ZLZLZLZL ZL2 λ 4λ 4λ 4 3λ 4sum Σ beam 1beam 2 difference Δbeam 1 beam 21 234 sum Σdifference Δ     Figure 13.5  Reception with a monopulse antenna for the ψ−plane (equivalent θ−plane).   Left: 6x λ/4 Hybrid.  Right: Magic Tee. 
 The train ofpulses is‘‘rectified” bythecathode-ray tube, sothat 4.5kclsecII II oscdlator Scansynchro Controlsynchro ——AY-101 AY-101 I Ampl!fler _Detector, T +300V &6sr47.—-- ‘F100k 3WA---- r * Im$150k f6SN7 --- M0,01 ?5k300k Pulsedoscillator +150V 4 +36SN7 47k --- ~r0.0001 IL L1 FIG.13.34 .—Synchro null indices. themarker appears asarow ofdots which merge except onfairly fast sweeps. Anoscillation ofthis sort ispreferable toasimple rectangular pulse ifthe signals are tobepassed through mixing orother circuits whose low-frequency response isnot asgood as demanded bythevery long (asmuch as~see) marker pulse. 
 ING LOBES )N A SPECIFIC EXAMPLE PRESENTED IN &ARINA AND 4IMMONERI  TWO CARRIER  FREQUENCIES ARE USED AND THE VALUES OF  DK WHERE h Dv IS THE INTER 
 This permits the AFC crystal tobe operated atapredetermined power level. The alternative-taking the AFC information from the output signal ofthe radar crystal arising from transmitter power that leaks through the TR switch-has been used but suffers from serious disadvantages. The leakage power may be10to20times that desired formost favorable operation ofthecrystal, and isvariable from one TR tube toanother. 
 Enhanced solar activity impacts on the ionosphere in many ways, but its most sig - nificant action from a radar perspective is to produce substantially higher ionization  levels that persist at usable levels through the night, so higher radar frequencies can be  employed and the minimum achievable range decreases. In addition, the height of the  maximum electron density increases, so one-hop propagation can reach greater ranges.  FIGURE 20.6  The variation of the monthly median sunspot number since 1956, the year of the first opera - tional skywave radar detections ch20.indd   17 12/20/07   1:15:36 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 NUMBER O  K  &P X    IS A FUNCTION OF POLARIZATION  P  GRAZING ANGLE  X   AND THE  ELECTRICAL PROPERTIES OF SEAWATER  H IS THE RMS SEA WAVEHEIGHT AND  #Y  IS THE SURFACE  CORRELATION COEFFICIENT /F COURSE  THE REDUCTION OF A COMPLICATED BOUNDARY 
 If all those factors affecting radar range  were known, it. would be possible, in principle, to make an accurate prediction of radar  perfoqnance. But, as is true for most endeavors, the quality of the prediction is a function of  the amount of effort employed in determining the quantitative effects of the various pa­ rameters. 
 ¤ ¦¥³ µ´§ ©¨ ¨¶ ¸· ·COSQ    &)'52%    0HASOR  DIAGRAM  FOR  SIMULTANEOUS  SCANNING  AND  MOTION   COMPENSATION.   !)2"/2.% -4)  Î°£ WHERE P IS THE DIRECTION OF THE CLUTTER CELL WITH RESPECT TO THE ANTENNA POINTING ANGLE  WHEN THE SECOND PULSE IS RECEIVED AND  VR IS THE ANTENNA SCAN RATE 4HE SUBSCRIPTS ON  THE RECEIVED SIGNALS 3I AND $I INDICATE THE PULSE RECEPTION SEQUENCE 4HE DIFFERENCE PATTERN  $ IS USED TO GENERATE AN IN 
 As shown in Figure 3b, the Lungui Highway is located close to three hydrological systems: the Xi River and the Rongui and Shunde Branch Rivers. Plenty of ponds and a large amount of silt are distributed along the route. Figure 3. 
 This, unfortunately, is seldom done. It  is suspected that sometimes the decision as to which RF power source to use is deter - mined by what the radar system designer thinks the buyer (or customer) of the radar  desires. Sometimes the buyer will actually specify the type of transmitter to be delivered. 
 POWER  BEAMWIDTH IN %Q   OR %Q   WITH AN ERROR THAT IS USUALLY ONLY  OR  D" #LUTTER 3TATISTICS  3UMMARIES OF CLUTTER MEASUREMENTS MADE BEFORE ABOUT   MAY BE FOUND IN SEVERAL OF THE STANDARD REFERENCE BOOKS ON RADAR  AND RADAR CLUTTER   !MONG THE PROGRAMS OF THIS PERIOD  THE MOST AMBITIOUS WAS THAT PURSUED IN THE LATE S AT THE .AVAL 2ESEARCH ,ABORATORY .2,    IN WHICH AN AIRBORNE FOUR 
 Chen, W. C. Lee, R. 
 Deng, Z.; Ke, Y.H.; Gong, H.L.; Li, X.J.; Li, Z.H. Land subsidence prediction in beijing based on ps-insar technique and improved grey-markov model. Giscience Remote Sens. 
 NOISE RATIO  NOT THE SIGNAL 
 (8) Then, three pairs of sub-view images can be formed to get three position offsets. The system of equations is as follows. Δf=Tac/bracketleftBigg edr 3 2e3rd/bracketrightBigg , (9) where: Δf=[Δfd,12Δfd,13Δfd,23]T Tac=⎡ ⎢⎣tac,1−tac,2 t2 ac,1−t2 ac,2t3 ac,1−t3 ac,2 tac,1−tac,3 t2 ac,1−t2 ac,3t3 ac,1−t3 ac,3 tac,2−tac,3 t2 ac,2−t2 ac,3t3 ac,2−t3 ac,3⎤ ⎥⎦. 
 It is used for a irborne missile approach tracking , air  traffic c ontrol, and medical applications ( e.g. blood flow   monitoring ).  The RF pulse characteristics reveal  a great deal about a  radar's capability. 
 DOPPLER PLANE WITH ZERO RELATIVE TIME DELAY AND ZERO DOPPLER FREQUENCY  AND THE SECOND TARGET IS AT RELATIVE TIME DELAY  S  AND DOPPLER FREQUENCY  F D 4HE RELATIVE TIME DELAY  IS POSITIVE WHEN THE SECOND TARGET IS FARTHER IN RANGE THAN THE REFERENCE TARGET AND THE DOPPLER FREQUENCY IS POSITIVE FOR AN INCOMING TARGET 4HE MATCHED 
   FREQUENCY RADAR &2   OPERATING WITH BOTH HORIZONTAL AND VERTICAL POLARIZATIONS AT 5(&  -(Z   , BAND  -(Z   # BAND  -(Z   AND 8 BAND  -(Z   MADE CLUTTER MEASUREMENTS UPWIND  DOWNWIND  AND CROSSWIND IN WINDS FROM  TO  KT FOR GRAZING ANGLES BETWEEN  AND  4HE SYSTEM WAS CALIBRATED AGAINST STAN 
 REFLECTOR ANTENNAS  12.376x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 12 mass and volume constraints generally have a significant impact on the reflector system  design. Furthermore, some sort of stowage and deployment of the reflector is some - times required, especially for larger reflectors. These considerations and constraints  drive the choices of materials, structural designs, passive and active mechanisms, etc. 
 This page has been reformatted by Knovel to provide easier navigation. xxvi     Contents   Phase-Comparison Monopulse  ..........................  18.17  Monopulse Tracking with Ph ased Arrays   ............ 
 Int. J. Appl. 
         
 This fluctuation is  referred to as fading . Fading is significant for the radar engineer because one must account for the fact  that a single sample of the radar return may vary widely from the mean described by  s 0. Thus , the system must be able to handle the dynamic range of fading, which may  exceed 20 dB. 
 One of the attractions or the rigid radome is its ability to withstand the rigors of severe  climate. Rime ice, I.he prevalent type or icing found in the Arctic region, has little or no effect  on most radomes. Although it tends to collect on many types of structures and can obtain large  thicknesses. 
 Azimuth Resolution Factor of the Ambiguity Function. The azimuth resolu- tion capability of the system can be determined from an evaluation of the sum term written as the factor in Eq. (21.26). 
 · t\ New Aprroach to I .inear Filtering and Prediction Problems. Trans. ASM E . 
 29 -30,  May 1, 19 58, AFCRC-TR-58- 145(1), ASTl A Document 152409.  58. Bacon, G. 
 M. A. Sletten and D. 
 and G.S.; Resources, Z.B.; Software, Y.W. Funding: This research was funded by the National Key R&D Program of China, grant number 2017YFC1405600. Conﬂicts of Interest: The authors declare no conﬂict of interest. 
 BEAM CLUTTER RETURN IS POSITIONED TO $# THROUGH CLUTTER POSITIONING VIA AN &)'52%  3IDELOBE CLUTTER 
 PROPAGATION OF RADAR WAVES 443  assumes that h, ~ l,0. The phase difference .corresponding lo the path-length difference is  (12.2)  To this must be added the phase shift tjf, resulting from the reflection of the wave at M, which is  assumed to be TC radians, or 180°. The total phase difference between the direct and the ground­ reflected signals as measured at the target is  (12.3)  Tile resultant of two signals, each of unity amplitude hut with phase difference t/1, is  [ 2( I + cos 1/1 )J 111. 
 CALLY FOCUSES THE MOVING TARGETS &IGURE  A SHOWS A CONVENTIONALLY PROCESSED 3!2  IMAGE CONTAINING THREE MOVING TARGETSA MILITARY TRUCK TYPE -   A TRACTOR 
 Ó{°{{  2!$!2 (!.$"//+   KM FROM THE RADAR 4HE TWO CIRCULAR TURNS ARE PERFORMED AT AN ACCELERATION OF   G 4HE TRANSMITTED 3/* NOISE IMPACTS THE RADAR WITH POWER  F   NOT EXCEEDING EIGHT  TIMES THE RECEIVER NOISE POWER 4HUS  A 3/* WILL NOT COMPLETELY HIDE A TARGET  AND IT CAN BE DEFEATED WITH A HIGHER ENERGY WAVEFORM )N 2'0/  THE TARGET UNDER TRACK REPEATS WITH DELAY AND AMPLIFICATION THE RADAR PULSE SO AS TO PULL THE RADAR RANGE GATE OFF THE TARGET 4HE TIME DELAY IS CONTROLLED SO THE FALSE TARGET IS SEPARATED FROM THE TRUE ONE WITH EITHER LINEAR OR QUADRATIC MOTION &OR THE LINEAR CASE  THE RANGE OF THE FALSE TARGET 2 KFT IS RELATED TO THE RANGE OF THE TRUE TARGET 2KT VIA   22 V T TKKT KFT PO 
 The am- plitude range for each plot is 60 dB. The peaks at zero-doppler frequency are due to land in an antenna sidelobe. The target doppler coincides with a resonant line at 4.93 Mhz; it is between the lines below that frequency and outside them for frequencies above. 
 ..  25. Whelton, C. 
 AVAVAVAVAVAVA FIG, 3  To summarize, therefore, the average radio circuit is  handling wave~forms which can roughly be represented  as in Fig. 3. The radar receiver and transmitter, how-  ever, will be handling a square wave, such as is shawn  . 
 III, Fig. 21.41, p. 1856. 
 Conf. HF Radio Systems and Techniques , July 1991,  pp. 48–53. 
 In addition, we can judge that the dihedral used in Gotcha experiment is set vertically because the RCS curve of it is the same as the curve of dihedral B in the simulation. The RCS curve of the vehicle is as expected. The four sides of the vehicle cause substantial scattering in four directions and barely any scattering in other directions. 
 THE 
 34!4% 42!.3-)44%23   ££°£Î -/#6$  FABRICATION TECHNIQUES TO ACHIEVE THE HIGH PERFORMANCE CHARACTERISTICS  4HESE ARE CAPITAL 
 BIASED AMPLIFIER STAGE ARE AS FOLLOWS L .O QUIESCENT DC CURRENT IS DRAWN WHILE THE DEVICE IS NOT BEING DRIVEN  SUCH AS IN  THE RADAR RECEIVE MODE (ENCE  THERE IS NO POWER DISSIPATION IN THE AMPLIFIER WHILE THE TRANSMITTER IS OPERATING IN THIS MODE L /NLY ONE POWER SUPPLY VOLTAGE IS NECESSARY FOR THE COLLECTOR TERMINAL OF THE TRANSIS 
 (Available from DTI Internet site www.divtecs.com.) 53. K. J. 
 In a valve  it is customary to place the greatest positive potential  on the plate, or anode—say, 150 or 100 volts, compared  with only 100 or 120 on any intermediary grid—and the  anode is relatively close to the cathode, so there is a  heavier electron-flow, or, as we say, a-greater flow of  anode current. By this we really mean a greater flow of  electrons to the anode.  In the CRT we use a considerably greater voltage on  the electrodes corresponding to the valve anode, often  as much as 3000 volts. 
 = ^ P,,.G,,. An-(T0A A, Pr ~ 1 (*a*tf Here a° has been used to denote the average value of (j,/A A1-. In this formulation, we may pass in the limit from the finite sum to the integral given by __ i c PtGtArv*dA pr = -~ I -^-^-l 02.1)/4 \2 J r>4 ^ 7^ Illuminated area ^ The bar over Pr implies the average value. 
 Airborne weather radars are constrained by size  and weight limitations. Ground-based radars may be constrained by cost and siting  considerations. Severe storm warning radars require long range and high unambigu - ous velocity and then must penetrate very heavy rain, thus dictating long wavelengths. 
 It should be noted that radar cross sections of ships can be several thousand square meters, while those of tanks typ- ically range from 25 to 125 m2.17 For severe clutter and reduced target cross sections, coherent processing may be required. Although stationary or very slow-moving targets cannot be discrim- inated from clutter on the basis of doppler frequency, use of doppler beam sharp- ening or synthetic aperture techniques can reduce the effective size of the reso- lution cell and hence increase the signal-to-clutter ratio in the cell containing the target.18 Angle tracking can thus take place to provide the required data for guid- ance. Air Targets.4'16 Although some early systems were designed to use non- coherent pulse waveforms, they were not suitable for low-altitude (high-clutter) op- eration against small-cross-section aircraft targets. 
 J. Farrell, J. Plaut, A. 
 The setisfully described in Sec. 8“13ofVol. 2ofthis series.. 
 The main operator controls included: Power-up push buttons (LT OFF, LT ON and HT ON) with associated indicator lamps; Lucero switch; Figure 3.8. Switch unit type 207 [ 4].Airborne Maritime Surveillance Radar, Volume 1 3-11. Scanner switch; Line of ﬂight marker switch; 10 mile zero control; Range marker control; Height marker control; Range scale and range marker scale selection; Receiver gain. 
 Rec., vol. 2, pt. 1, pp. 
 62.  pp 664 673. June, 1974. 
 Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). 294. 
 TIME FIG. 14.15 Schematic diagram for a sinusoidally modulated FM. FREQUENCY . 
 E. O. Brigham, The Fast Fourier Transform , New York: Prentice Hall, 1974, pp. 
 $ $ 
 Then,  when we turn the. aerial array towards an object giving  an echo, we shall see the spike blip of light on the CRT  standing out above the grass, and thus again we can  measure the length of this echo. The two measure-  ments can be compared as a ratio, and this ratio of signal  deflection (echo-length) to the mean noise-level is called  the S/N ratio, or the ‘Z factor.” Thus the limit of  reception on any given radar set is when the Z factor = 1,  for then the greatest echo is no longer than the average  depth of grass. 
 FICIENT FOR TARGET DETECTION EVEN THOUGH THE 3#6 OF THE RADAR BASED ON AVERAGE CLUTTER  MAY BE RELATIVELY LOW 4O ACHIEVE )#6  A MECHANISM MUST BE FURNISHED TO PROVIDE #&!2 OPERATION AGAINST THE RESIDUE FROM STRONG CLUTTER 4HIS #&!2 IS PROVIDED IN OLDER -4) SYSTEM BY )& LIMITING  AND  IN THE -4$ IMPLEMENTATION  THROUGH THE USE OF  HIGH 
  AND THE ,UNAR 2ECONNAISSANCE /RBITER ,2/   INCLUDE IN EACH OF  THEIR PAYLOADS A h-INI 
 Usually the pulser canbemore easily modified than themagnetron ifmode-shifting ormode- jumping occurs. Inany event, many interacting adjustments must be made before full power output can beassured. Sometimes achange in ther-floading ofthemagnetron, injtsheater current, orintheshape of the magnetic field will succeed ~vhere altering thepulse shape has failed. 
 Speckle Filtering in Satellite SAR Change Detection Imagery. Int. J. 
 13ofthisseries.. 156 C-W RADAR SYSTEMS [SEC. 5.11 inaddition tothose atOand 1000 cps. 
 Thinned Arrays. The number of radiating elements in an array may be reduced to a fraction of those needed completely to fill the aperture without suffering serious degradation in the shape of the main beam. However, average sidelobes are degraded in proportion to the number of elements removed. 
 FLIGHT IS UNCHANGED BY THIS SUBSTITUTION $AVIES  PROVIDES A CLEAR EXPLANATION OF THESE USEFUL THEOREMS. 
 39. Wilson, J. D.: Probability of Detecting Aircraft Targets, IEEE Trans., vol. 
 ● The development of radars suitable for air-traffic control. ● Pulse compression. ● Monopulse tracking radar with good tracking accuracy and better resistance to elec - tronic countermeasures than prior tracking radars. 
 FED REFLECTOR WITH TRIPOD STRUTS  SIDE VIEW  AND AXIAL VIEW. 
 17 Examples of the variation with angle of incidence  of the number of independent samples for a scatterometer ch16.indd   25 12/19/07   4:55:50 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Ground Echo. 
 ON ASPECT LIES AT  n AT BOTH  SIDES OF THE CHART !S SHOWN IN 4ABLE   THE APPROXIMATE 2#3 OF A STRAIGHT EDGE OF LENGTH  , PRE 
 The photomixing receiver is more complicated  than the direct photodetection receiver and it requires a stable transmitter and local oscillator.  When the target is in motion relative to the radar a large doppler frequency shift occurs which  can place the echo signal outside the receiver passband. For example, with a relative velocity of  5 m/s ( 10 kt) the doppler rrequency shift at l-1,m wavelength is 10 MHz. 
 Equation (8.29) indicates an error of  0.22 x 10-4 radian ( -0.001°) for a 100-by-100-element uniformly illuminated array with a  beam width of approximately 1 ° when a = 0.4. 320 INTRODUCTION TO RADAR SYSTEMS  Leichter's analysis 111 of beam-pointing errors was performed for a continuous line  source, but may be applied to a linear array. Both uniform distributions and modified Taylor  distributions were considered. 
 For most areas, little  difference was found between vertical and horizontal polarizations, so the results were  reported for data groups including both polarizations. Figure 16.48 shows the results,  grouped by target class.FIGURE   16. 47 Phase differences for different surface classes in the Amazon basin at C band and L band179 CHH-CVV Phase Differences LHH-LVV Phase DifferencesWater Clearing Macrophyte Fores t Flooded forest Water Clearing Macrophyte Fores t Flooded forest0 90 270 180 0.20 90 270 180 0.20 90 270 180 0.20 90 270 180 0.20 90 270 180 0.2 0 90 270 180 0.20 90 270 180 0.20 90 270 180 0.20 90 270 180 0.20 90 270 180 0.2 ch16.indd   53 12/19/07   4:56:47 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 ENCES INCLUDE ADAPTATION TO ENVIRONMENT  FREQUENCY AND WAVEFORM SELECTION  RADAR CROSS SECTION  PATH LOSSES  MULTIPATH EFFECTS  NOISE  INTERFERENCE  ANTENNA GAIN  SPATIAL RESOLUTION  AND CLUTTER &OR THE CASE OF NOISE 
 Thesering-angels areassociated withbirdsflyingawayfromroostingareas.Angelscanalsobe causedbysecond-time-around echoesorlargesignalsthatentertheradarviatheantenna sidelobes. REFERENCES 1.Skolnik, M.I.:SeaEcho,chap.26of"Radar Handbook," M.I.Skolnik (ed.)McGraw-Hili Book Company, NewYork,1970. 2.Guinard, N.W.,J.T.Ransone, Jr.,andJ.C.Daley:Variation oftheNRCSoftheSeawithIncreasing Roughness, J.Geophys. 
 ING LESS LINES OF CODE  THE *6# ALGORITHM GENERALLY REQUIRES LESS COMPUTATION TIME   0ROBABILISTIC $ATA !SSOCIATION 0$!   !NOTHER ALTERNATIVE IS THE PROBABILISTIC  DATA ASSOCIATION 0$!  ALGORITHM    WHERE NO ATTEMPT IS MADE TO ASSIGN TRACKS  TO DETECTIONS  BUT INSTEAD  TRACKS ARE UPDATED WITH ALL THE NEARBY DETECTIONSWEIGHTED BY THE PERCEIVED PROBABILITY OF THE TRACK BEING THE CORRECT ASSOCIATION "ECAUSE 0$! RELIES ON ERRONEOUS ASSOCIATIONS ESSENTIALLY hAVERAGING OUT v IT IS MOST EFFECTIVE WHEN TRACKS ARE FAR ENOUGH APART THAT NEARBY DETECTIONS ORIGINATE FROM SPATIALLY RANDOM NOISE OR CLUTTER EXCLUSIVELY AND WHEN THE TRACKING GAINS ARE SMALL IE  WHEN THE TRACKING INDEX  F TRACK IS SMALL  4HE *OINT 0ROBABILISTIC $ATA 4RACK .O $ETECTION .O  $ETECTION .O  $ETECTION .O     c       cc  FROM ' 6 4RUNK 4!",%  !SSOCIATION 4ABLE FOR %XAMPLE 3HOWN IN &IGURE  . Ç°{ä  2!$!2 (!.$"//+  !SSOCIATION *0$!  IS AN EXTENSION OF 0$! THAT HANDLES MORE CLOSELY SPACED  TARGETS )N *0$!  DETECTIONS ARE WEIGHTED LESS WHEN THEY ARE NEAR ANOTHER TRACK   -ULTIPLE (YPOTHESIS !LGORITHMS  4HE MOST SOPHISTICATED ALGORITHMS ARE MULTIPLE  HYPOTHESIS ALGORITHMS IN WHICH ALL OR MANY  POSSIBLE TRACKS ARE FORMED AND UPDATED  WITH EACH POSSIBLE DETECTION   )N 4ABLE   TRACK NO  WOULD BECOME THREE  TRACKS OR HYPOTHESES   CORRESPONDING TO UPDATING WITH DETECTION NO   DETECTION NO   AND NO DETECTION %ACH OF THESE TRACKS WOULD UNDERGO A +ALMAN FILTER UPDATE AND BE ELIGIBLE FOR ASSOCIATION WITH THE NEXT SET OF DETECTIONS 4RACKS ARE PRUNED AWAY IN A SYSTEMATIC MANNER LEAVING ONLY THE MOST PROBABLE &IGURE  ILLUS 
 D" WINDOW OF  2& INPUT DRIVE 4HIS BECOMES STRIKINGLY CRITICAL WHEN SEVERAL #LASS 
 40. 130 ._____e• ,,-I~--c=- till 100Figure13.14Radarcrosssectionorbirds (withclosedwings)atSband.Vertical polarization. Solidcirclesapplytoaverage values*20°aroundbroadside, x'sapplyto theaVl"rap.{' orthe±20°sectoraboutthe headandthe±20°sectoraboutthetail. 
 J. P. Hansen, “High resolution radar backscatter from a rain disturbed sea surface,” presented at  ISNR-84 Rec., Tokyo, October 22–24, 1984. 
 Equation 8.3 applies to isotropic radiating elements, but practical antenna elements that are  designed to maximize the radiation at O = 0°, generally have negligible radiation in the direc­ tion O = ± 90°. Thus the effect of a realistic element patt~rn is to suppress the grating lobes at  ± 90',. It is for this reason that an element spacing equal to one wavelength can be tolerated for  a nonscanning array. 
 It is simply a function computed from the reciprocal of  a true adapted antenna pattern. Superresolution and adaptive antennas for jammer can - cellation are intimately related. Roughly speaking, the difference is that one produces  a pattern with the nulls down (adaptive antenna for jammer cancellation) and the other  with the nulls up, i.e., peaks (superresolution of jammers). 
 The  prime difference between optical and microwave refraction is that water vapor has a negligible  effect on the former; consequently the second term of Eq. (12.9) may be neglected at optical  frequencies. Since the barometric pressure p and the water-vapor content e decrease rapidly  with height, while the temperature T decreases slowly with height, the index of refraction  normally decreases with increasing altitude. 
 MALLY BENIGN CONDITIONS ON THE BRIDGE OF A LARGE MODERN SHIP  THE DISPLAY AND RADAR PROCESSOR CAN BE SUBJECT TO HIGH LEVELS OF SHOCK AND VIBRATION AND MUST MEET HIGH VARIATIONS IN TEMPERATURE  
 A P-4. pp. 60, 609, October,  1956. 
 ALARM PROBABILITY ACCORDING TO  0F    
 The induction motor rating should beabout 50per cent larger than that required todrive the alternator. Itis desirable tohave the alternator output the same asthe ship’s power so that theradar system can beoperated directly from the ship’s supply in case ofbreakdown ormaintenance shutdown ofthemotor-alternator set. The motor may bedirect-coupled orbelt-connected tothealternator; usually direct coupling ispreferred because ofitssimplicity. 
 Arancibia, “A sidelobe blanking system design and demonstration,” Microwave J ., vol. 21,  pp. 69–73, March 1978; reprinted in Ref. 
 .2#3  .   '2/5.$ 0%.%42!4).' 2!$!2   Ó£°Ó£ THAT THE PEAK SIGNAL OUTPUT TO MEAN NOISE RATIO IS GREATER THAN CAN BE ACHIEVED WITH ANY  OTHER LINEAR FILTER 4HIS IS NOT  ALWAYS THE BEST FILTER TO USE  FOR TIME 
 (24), thegreatest possible subclutter visibility is26db. There isthen noneed tomake theindividual subclutter risibilities forscanning and wind greater than 30db. For thecase ofscanning, that means, from Eq. 
 Raven, and P. Waterman, Airborne Radar , Boston: Boston  Technical Publishers, 1965, pp. 203–207. 
 The echo from the ground directly beneath the aircraft is  called the altiwde return. The altitude return is not shifted in frequency since the relative  velocity between radar and ground is essentially zero. Clutter to either side of the perpendicu­ lar will have a relative-velocity component and hence some doppler frequency shift; con­ sequently the clutter spectrum from the altitude return will be of finite width. 
 Thechoiceofpolarization alsoinfluences thea'mount ofseaorlandabsorption. Vertical polarization isabsorbed morethanhorizontal. Thetotalantenna temperature canbefoundbyintegrating thetemperature" seen"bythe antenna, weighted bytheantenna gainovertheentiresphere.60 '7:~'f78(0,c/J)G(O,c/J)dO. 
 Practical Detectors.  Many different detectors (often called integrators ) are used  to accumulate the radar returns as the radar sweeps by a target. A few of the most  common detectors7 are shown in Figure 7.3. 
 10.22  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 rectangular pulse, a large bandwidth would likely cause interference to other radars  and other electromagnetic systems. For this reason, government frequency allocation  agencies usually require that the frequency spectrum from a radar not contain large  energy at other frequencies. This is becoming more important as the occupancy of the  electromagnetic spectrum is increasingly crowded with transmitters. 
 This is especially useful in an air-traffic-control display in which such information as target  ide~ltity a~id altitude is desired to be displayed. The positions of targets on a predeterniiried  number of previous scans might be shown on a synthetic display, or a line might be generated  tb indicate the direction of the target's trajectory and the target's speed. (The length of the  line can be made proportional to target speed.) The use of a computer to generate the  grapllicq arid coritrol the CRT display offers flexibility in the choice of such things as range  scales, olfcenter displ;ty, blow-up of selected areas, physical map outlines, grid displays, airport  runways, stored clutter map, raw video, outlines of areas of weather blanked by the operator,  tlispiay of stored flight plans, arid time-compressed display of several successive radar scans. 
 S. Pearson, “On the problems of the most efficient tests of statistical hypoth - eses,” Philos. Trans. 
 The entire unit rotates at a 6 rpm rate. It houses a broadside array of Yagi-type  endfire elements.  It' 1. 
 SIGHT PROPAGATION IS TO REDUCE THE ANGLE OF THE LOWEST LOBE  BRINGING IT CLOSER TO THE SURFACE      &  $ ! #!  ##   !  %%                 "'!  !$$( 
 Lines ofconstant height arehorizontal and equally spaced. Arrangements aresometimes made tomove therange origin offthetube face toallow expansion ofaregion ofinterest. Iftheheight-finding antenna isrequired toscan over anappreciable range ofazimuth angles, theRHI isusu- ally blanked except during arelatively10,OOO narrow azimuth sector, inorder toimprove the ratio ofsignal tonoise and toavoid ZPconfusion between targets atdifferent ; azimuths. 
 This was said to apply to a good operator  viewing a PPI under good conditions. Its degree of applicability, however, is not clear.  It is not iinusual to find no accoutlt of the operator loss being taken in the radar equation. 
 705-706, December, 1957.  50. Payne-Scott, R.: The Visibility of Small Echoes on Radar PPI Displays, Proc. 
 2 INTRODUCTION TO RADAR SYSTEMS  The name radar reflects the emphasis placed by the early experimenters on a device to  detect the presence of a target and measure its range. Radar is a contraction of the words radio  detection and ranging. It was first developed as a detection device to warn of the approach of  hostile aircraft and for directing antiaircraft weapons. 
 MADE SLING OR HARNESS TO SUPPORT THE TARGET 4HE FIRST USES A SINGLE OVERHEAD SUPPORT POINT AND GUY LINES TO A FLOOR 
 Tlle evaporation duct that lies just above the surface of the sea is a result of  tlie water vapor. or liumidity, evaporated from the sea. The air in contact with the sea is  saturated 14tIi water vapor, wit11 a saturation vapor pressure appropriate to the temperature  of tl~e sea si~rface.'~ The air several meters above the sea is not usually saturated so there will  be a gradual decrease in water vapor pressure from the surface value to the ambient value well  above tlie surface. 
 %*$) '!# ' 
 Platform  is a generic term referring to the  vehicle where the radar and antenna are installed. Typical radar platforms include  pedestal (fixed site), ground vehicles, ships, airplanes, UA Vs, and spacecraft/satellites.  The following short section is devoted to platform impacts and some key associated  design drivers. 
 Some of the prediction methods have not been well documented although  widely distributed; also, users frequently “improve” upon a model and prediction  method to suit their specific needs. As an example, the model RADAR C29 is the basic  building block of Thomason et al. in NRL Report 832122; however, they added a D  region, a collision-frequency distribution, an Earth’s magnetic field, a topside elec - tron distribution, an auroral electron-density modification,34 and other features that  make the model more generally useful. 
 Conf ., September 14–16, 1964, pp. 259–263. 11. 
 The term pseudo-monostatic  will be used to characterize bistatic  geometries that approximate monostatic operation. 23.2 COORDINATE SYSTEMS A two-dimensional north-referenced coordinate system21 is used throughout this chapter.  Figure 23.1 shows the coordinate system and parameters defining bistatic radar opera - tion in the ( x, y) plane, also called the bistatic plane .22 The bistatic triangle lies in the  bistatic plane. 
 The sine pulse, inaddition toitstracking role, triggers aflip-flop controlling the cosine-pulse switch, and thecosine pulse similarly triggers aflip-flop con- trolling themodulator pulse switch. The modulator pulse ispassed onto theindicators and, inaddition, triggers aflip-flop which closes theswitch ahead ofthedecoder while video signals arebeing received, and opens it shortly before thenext basic pulse. Afew words should besaid about theprocess of“locking in” initially orafter tracking has been lost through failure ofsignals orsevere inter- ference. 
 It was shown in Chap. 2  that the dividing line between these two regions depended upon the probability of a false  alarm, which in turn is related to the average time between false alarms.  There are two types of errors that might be made in the decision process. 
 Electron ., vol. 16,   pp. 170–185, October 1984. 
 Maffett, F. Smith, R.C. Heimiller, and A. 
 24,Sec. 6.2. The latter effect makes the detection ofadesired target echo within therain clutter even more difficult, forthevery persistence ofthetarget echo onsuccessive pulses helps greatly todistinguish itfrom noise (Sec. 
 In fact, the sharp falloff of the nonducting  data in  Figure 15.18 might be further evidence of the threshold shadowing  mentioned earlier.  However, the common idea of shadowing derives from the geometrical optics concept  of a sharp transition between light and darkness. By considering the implications of  diffraction  at the wave peaks, it is possible to determine the domain of radar frequen - cies and wind speeds over which the concepts of geometrical optics may be applied. 
 Further, it can be shown that the average SCR improvement calculated for a single filter is equal to the MTI improvement factor as defined in Sec. 15.4. The basis for obtaining the optimum MTI filter is again the covariance matrix of the clutter returns as given by Eq. 
 (Ajler Sa~nders,~ IRE Trans.)  CWANDFREQUENCY-MODULATED RADAR89 whereJ0,JI,J2,etc=Besselfunctions offirstkindandorder0,I,2,etc.,respectively D=(~I/f~)sin2rrf~Role Ro=distance totargetattimet=0(distance thatwouldhavebeenmeas­ urediftargetwerestationary) c=velocity ofpropagation Id=2l',.f~/c=doppler frequency shift 1',=relative velocity oftargetwithrespecttoradar <Po=phaseshiftapproximately equaltoangular distance 4rrfoRole cPm=phaseshiftapproximately equalto2rrfmRole Thedifference-frequcncy signalofEq.(3.16)consists ofadoppler-frequency component ofamplitude Jo(D)andaseriesofcosinewavesoffrequency 1m'~rm,~rm'etc.Eachofthese harmonics off~ismodulatcd byadoppler-frequency component withamplitude proportional toJn(IJ).Theproduct ofthedoppler-frequency factortimesthenthharmonic factorisequiva­ lenttoasuppressed-carrier double-sidcband modulation (Fig.3.15). Inprinciple, anyoftheJncomponents ofthedifference-frequency signalcanbeextracted inthcFM-CW radar.Consider firstthedoctermJo(D)cos(2rrfdt-4>0)'Thisisacosinewave atthctloppler frequency withanamplitude proportional toJo(D).Figure3.16showsaplotof severaloftheBesselfunctions. Theargument DoftheBesselfunction isproportional torange. 
 22.11 Maximum time for viewing objects from a space vehicle if the objects are tracked.28 3. Atmospheric propagation problems can be minimized by proper selection of operating frequencies and favorable geometry selection. 4. 
 The  MTI in the lower beams can be optimized for surface clutter and MTI in the upper beams, ~f  used at all, can be optimized for rain and chaff. The individual pencil beams have a higher gain  than a fan-beam antenna, and can provide a larger number of hits at a higher data rate than  can a 3D radar with a single scanning beam in elevation. -)  Scanning pencil beam. 
 Any use is subject to the Terms of Use as given at the website. Electronic Counter-Countermeasures.  ELECTRONIC COUNTER-COUNTERMEASURES  24.636x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 100. B. 
 11.6 Measured RCS pattern of a dipole 5.221X long. (Courtesy of University of Michigan Radiation Laboratory.6) Figure 11.7 shows the broadside resonances of a wire dipole as a function of dipole length. The first resonance occurs when the dipole is just under a half wavelength long, and its magnitude is very nearly X2. 
 III and ASV Mk. VI are shown in ﬁgures 4.33 and4.34. Figure 4.33 compares detection ranges for a U class submarine, either beam-on or end-on to the radar. 
 23-25, 1973, pp. 292-296.  42. 
 MTI-14,  pp. 24 -28, January, 1966.  41. 
 STAP is a fairly broad topic that has applicability beyond this chapter on airborne  MTI radar. The primary motivation for STAP is to improve clutter cancellation perfor - mance and to better integrate a radar’s spatial processing (antenna sidelobe control and   sidelobe jamming cancellation) with its temporal clutter cancellation processing. The applicability of STAP to improving clutter cancellation must be assessed spe - cifically in the context of the key performance limiters to airborne MTI radar clut - ter cancellation as described at the start of this chapter. 
 11.20. This device generates a binary pseudorandom code of zeros and ones oflength  2" I, where n is the number of stages in the shift register. Feedback is provided by taking the  output of the shift register and adding it, modulo two, to the output from one of the previous  stages of the shift register. 
 POLARIZED RETURNS FROM  VOLUME SCATTERERS WITH ELEMENTS THAT ARE LARGE COMPARED WITH A  WAVELENGTH ARE STRON 
 A single "snapshot" of a PPI would not likely  differentiate the echo of a small target from that of the sea spikes. The individual sea spikes,  however, will disappear with time and new spikes will appear at other locations. If it is possible  to observe the radar display for a sufficient period of time, the small targets can be recognized  since they will remain relatively fixed in amplitude while the sea spikes come and go. 
 Isolation can also be increased by transmitting on an  orthogonal polarization to that received. Providing they are operating with linear  gain, there are no adverse effects from radar sidelobe interrogation. However, at  close ranges, the signal from the main beam of the radar may saturate within the  RTE, effectively enhancing the levels of the RTE received signal through the radar  sidelobes. 
 For a finite array the properties vary with location of the element within  the array. In some arrays, dummy elements are placed on the periphery so as to provide the  elements near the edge with an environment more like those located in the interior.  Although there have been many di!Terent kinds of radiators used in phased arrays, the  dipole. 
 PRODUCTS ARE GENERATED  WHICH REDUCE THE ECHOS MATCHED 
 Houze, Jr., and J. D. Locatelli: Real-Time Wind Measurement in Extratropical Cyclones by Means of Doppler Radar, /. 
 and T. F. Bush: Corn Growth as Monitored by Rada1. 
   2!$!2 $)')4!, 3)'.!, 02/#%33).'   Óx°ÓÇ #OMPARED TO &)2 FILTERS  ))2 FILTERS OFFER SEVERAL ADVANTAGES )N GENERAL  THEY REQUIRE  LESS PROCESSING AND MEMORY TO IMPLEMENT SIMILAR FUNCTIONS )T IS ALSO EASIER TO IMPLE 
 When tile wind is blowing toward the radar tlie dpproacliing-wavc  spectral line IS the larger of the two. When the wind is blowing away from the radar, the  receding-wave spectral line is the larger When the wind IS blowing perpendicular to  the direction of the radar beam, the two spectral lines are equal. Thus the relative magnitude  of the two major components of the doppler spectrum can provide a measure of the direction  of the wind. 
 ● The combiner should have RF isolation among ports, such that failed modules do not  affect the load impedances or combining efficiency for the remaining functioning  modules. ● The combiner should provide a controlled RF impedance to the amplifier modules,  such that the amplifier characteristics are not degraded. ● The dissipated power capability of the power combiner terminations should be suf - ficient to accommodate any combination of power amplifier failures. 
 BASED MEASUREMENTS 4HUS  BEING ABLE TO MEASURE STRONG PRECIPITATION ECHOES AT SHORT RANGE AND ALSO WEAK PRECIPITATION ECHOES AT LONG RANGE REQUIRES RADAR RECEIVERS HAVING A TOTAL DYNAMIC RANGE OF n D" WHEREAS MEASURING WEAK ECHOES IN THE PRESENCE OF STRONG GROUND CLUTTER REQUIRES AS LARGE AN INSTANTA 
 The calibrations shown in Figure 16.12 are incomplete without knowing the  antenna patterns and absolute gains. Since accurate gain measurements are difficult,  absolute calibrations may be made by comparing received signals (with proper rela - tive calibration) from the target being measured and from a standard target . Standard  targets may be metal spheres, Luneburg-lens reflectors, metal plates, corner reflectors,  or active radar calibrators (ARCs—actually repeaters).84,85 Of the passive calibrators,  the Luneburg-lens reflector is best because it has a large cross section for its volume  and has a very wide pattern so that alignment is not critical. 
 MAP 
 COST 643 SYSTEMS STILL COMMONLY USE SUBSYSTEMS INTENDED FOR SHIPBORNE USE  GIVING GOOD COST SAVINGS COMPARED TO CUSTOM 
 vi. Adjust the orientation of the PPI so that the upward direction on the tube face is the heading of the aircraft. This is effected by setting the track line onthe Perspex screen to zero, setting the switch on the heading control unit to manual, and turning the setting knob until the course marker lies under the track line. 
 9.26. Examples ofRadomes.—Types ofradomes vary greatly insize, shape, and method ofconstruction. Attention iscalled toafew repre- sentative radomes. 
 Patent No. 3,797,017, Mar. 12, 1974. 
 Atthesametime,moisture isaddedfromthesea toproduce amoisture gradient. Thisformofanomalous propagation overtheseatendstobe moreprominent ontheleeward sideoflandmasses.Ducting occursduringeitherthedayor nightandcanlastforlongperiodsoftime.Itismostlikelytooccur,however, inthelate afternoon andevening whenthewarmafternoon airdriftsoutoverthesea..B Thusthecharacter ofducting' islikelytodifferoverlandandsea.Landmasseschange temperature muchmorequickly than'does thesea.Asaresult,thereismuchmoreofadiurnal variation ofducting overlandthanoversea,whereitislikelytobemorecontinuous and widespread.32 .Superrefracting groundductsmayalsobeproduced bythediverging downdraft undera thunderstorm.3!Therelatively coolairwhichspreadsoutfromthebaseofathunderstorm resultsinatemperature inversion inthelowestfewthousand feet.Themoisture gradient is alsoappropriate fortheformation ofaduct.Ductformation bythunderstorms maynotbeas frequent asotherducting mechanisms, butitisofimportance sinceitmaybeusedasameans ofdetecting thepresence ofastorm.Anoperator carefully watching aradardisplaycanddcct thepresence ofastormbythesuddeninc'rease inthenumberandrangeofgroundtargets.The conditions appropriate tothe'formation Iofathunderstorm ductareshort-lived andhavea timeduration oftheorderof'perhaps 30minto1h. Withtheexception ofthunderstorms, ducting isessentially afine-weather phenomenon. 
 Thesumsignalhashigher sidelobes because theseparation between thephasecentersoftheseparate antennas islarge.(Thesehighsidelobes aretheresultof gratinglohes.similartothoseproduced inphasedarrays.)Theproblem ofhighsidelobes can hereduced byoverlapping theantenna apertures. Withreflector antennas, thisresultsinaloss ofanglesensitivity andantenna gain. 5.5TARGET-REFLECTION CHARACTERISTICS ANDANGULAR ACCURACyJo.41.Q5 Theangular accuracy oftracking radarwillbeinfluenced bysuchfactorsasthemechanical properties oftheradarantenna andpedestal, themethodbywhichtheangular position ofthe antenna ismeasured, thequalityofthes~osysteQ'l,thestability oftheelectronic circuits, the noiselevelofthereceiver, theantenna beamwidth, atmospheric fluctuations, andthereflection characteristics ofthetarget.Thesefactorscandegrade thetracking accuracy bycausingthe antenna beamtofluctuate inarandom manner aboutthetruetargetpath.Thesenoiselike fluctuations aresometimes calledtracking noise,orjitter. 
 This delay is quantized  by a range gate pull off (RGPO) device. A range gate stealer system linearly delays the  quantized signal in order to generate a constant range-rate false target. The joint effect  of phase and delay quantization in DRFM can be analyzed as reported in Greco, Gini,  and Farina.26 Other artifacts in the deception signals can be introduced by imperfections  in the down-up conversion and demodulation/modulation of the signal performed in the  DRFM device. 
 This is known as target classification.  The time delay between the transmission of the radar signal and the receipt of an echo is a  measure of the distance, or range, to the target. The range measurement is usually the most  significant a radar makes. 
 Any use is subject to the Terms of Use as given at the website. Synthetic Aperture Radar. 17 .36  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 17 34. R. 
 1, pp. 272-293, 1958.  42. 
 Improved Delay Line Technique Study, RADC Tech. Rept. RADC-TR-65-45, May 1965. 
 N.: Use of Bistatic Radar Techniques to Improve Resolution in the Ver- tical Plane, IEE Electron. Lett., vol. 4, pp. 
 The nature of the circuit may also demand that the  lagging edge be vertical, to produce an imstantaneous  cut-off. Such a wave-form is produced in the transmitter  modulator, the pulse of energy is broadcast, and a signal  received by the radar receiver. Now there is one impor-  tant difference between a radar and a broadcast radio  receiver. 
 into the holes of the hole-and-slot resonators to change the  inductance of the resonant circuit. A tuner that consists of a series of rods inserted into each  cavity resonator so as to alter the inductance is called a crown-of-thorns tuner, or a sprocket  t1111cr. The amount of mechanical motion of the tuning element need not be large (perhaps a  fraction of an inch at L band) to tune the frequency over a 5 to 10 percent frequency range. 
   (& /6%2 
 M.: A Note on Doppler-Shifted Signals, Proc. IEEE, vol. 54, pp. 
 It might  have a frequency-response characteristic similar to that of Fig. 3.2b. The low-frequency cutoff  must he high enough to reject the d-c component caused by stationary targets, but yet it must  he low enough to pass the smallest doppler frequency expected. 
 It is also possible to utilize a  common aperture for both transmit and receive, with equal transmit and receive beamwidths.  Duplexers would be required as in a microwave phased-array radar. The antenna might also  support several simultaneous, independent radar beams; or multiple beams can be generated  sequentially (a pulse burst). 
 For frequencies of 2 MHz to 57 GHz, AREPS uses the APM. For  HF sky wave communications, AREPS uses an HF modeling suite,22 consisting of a  fully 3D ionosphere ray trace model, an HF field strength model, and an HF noise  model. In addition to these EM propagation models, AREPS may optionally use two  internationally recognized ionosphere models, the Parameterized Ionospheric Model  (PIM)23 and the International Reference Ionosphere (IRI).24 In addition to the propaga - tion models, AREPS contains a system performance radar model, which is discussed  in the next section. 
 The reentering electrons, however,  might contain modulation which will be amplified in the next pass through the circuit. To  circumvent this the tube of Fig. 6.12 has a drift space to demodulate the electron stream so as to  remove this RF feedback. 
  2OWELL  AND  6 9UDIN  h!DVANCED MODELING OF  THE IONOSPHERE AND UPPER ATMOSPHERE v  %NVIRONMENTAL 2ESEARCH 4ECHNOLOGIES 2EPORT   !   *UNE   * + (ILL  h%XACT RAY PATHS IN A MULTISEGMENT QUASI 
 TIME AND FALL 
 Two-Pole Filter. The two-pole filter in Fig. 8.3c requires the storage of an intermediate calculation in addition to the integrated output and is described mathematically byLIMIT FOR MAX.STANDARD DEVIATION (FRACTION OF BEAMWIDTH) . 
 3.Duplexer, TR and ATR tubes. 4.Local oscillator. 5.Radar and AFC mixer. 
 They are often dual-band (3 and 9 GHz). The  ITU recommends that for pulse lengths of 0.2 µs or longer, the frequency accuracy of  the responding signal should be within ±1.5 MHz, and for pulses of less than 0.2 µs,  the frequency should be within ±3.5 MHz. Swept frequency racons are effectively  obsolescent but are still permitted. 
 Radar engineers can learn a great deal  from their communications colleagues who realize similar concepts for sof tware- defined radios  (SDR). In the future, the processing needs for communications are comparable to remote sensing  or even higher.   14.3 SDRS and SD -SAR System Aspects   Because the entire functionality of this new type of software -defined Radar sensors can be dow n- loaded, their operat ing modes may be multifunctional, selective, active, pa ssive and corrective. 
 Thesynthesis techniques whichapplytoarrayantennas usuallyassumeuniformly spaced isotropic elements. Theelement spacingisgenerally takentoheahalfwave-length. Ifthe elemerlts werenotisotropic buthadapatternEe(8),andifthedesiredoverallpatternwere denotedEd(8),thepatterntobefoundbysynthesis usingtechniques derived for.isotropic elements wouldbegivenbyEd(8)/Ee(8). 
 Finally, for the exponential clutter spectrum model, the optimum improvement fac - tor is shown in Figure 2.29, again as a function of the RMS relative spectrum width,  assuming zero mean for the spectrum. FIGURE  2.27 Optimum improvement factor for gaussian spectrum model ch02.indd   31 12/20/07   1:44:32 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 One of the advantages of a lens over a reflector antenna is the  absence of aperture blocking. Considerable equipmen1 can be placed at the focus of the lens  without interfering with the resultant antenna pattern. The first monopulse radars used lenses  for this purpose, but with time the monopulse RF circuitry was reduced in size and the  reflector antenna came to be preferred over the lens. 
 than with linear.79  An alternative to circular polarization is to transmit any linear polarization and receive  on the orthogonal linear polarization.79.!H Spherical raindrops will give no return in the  orthogonal channel if no cross-polarization distortion takes place in the radar or the propaga­ tion medium. There is some evidence to indicate that crossed linear polarization may give  better rain rejection than conventional circular polarization.  I .og-FTC receiver. 
 Only one power supply voltage is necessary for the collector terminal of the transistor. The Class-C operation is a self-bias, wherein the transistor draws collector current only when the RF voltage swing on the input exceeds the built- in potential of the emitter-base junction. Additional reverse biasing may be intro- duced as a result of the voltage drop induced by current flow across parasitic re- sistance of the base or emitter bias return, and in common-base operation this will result in degraded power gain. 
 TER REGION  HOWEVER  BY INTERPRETING  2 O AS THE RANGE WHERE THE SIGNAL IS EQUAL TO  SIDELOBE CLUTTER PLUS SYSTEM NOISEn 4HE #&!2 LOSS MAY ALSO BE HIGHER OWING  TO THE INCREASED VARIABILITY OF THE THRESHOLD WHEN THE CLUTTER VARIES OVER THE TARGET DETECTION REGION -ORE ACCURATE CALCULATIONS OF DETECTION PERFORMANCE IN THE SIDE 
 9.12. Inthefinal design oftheantenna mount, thereflectors fortheupper and lower beams are mounted back-to-back, sothat their axes differ by180°. This complicates somewhat the mechanism fortransmission ofazimuth-angle data from theantenna mount totheindicators. 
 This negates the benefit of the increased  signal-to-clutter ratio achieved by high resolution as expressed by Eq. (13.8) for the detection  of targets in clutter. (As will be discussed in Sec. 
  -ODES  -ODE 7IDTH 7 !CCESS 2ESOLUTION ,OOKS 13!27 13!2 3ELECTIVE POLARIZATION KM KM M  2G r !Z 2G r !Z 3TANDARD   n  r   r     7IDE   n  r   r     &INE    n  r   r      3CAN3!2 7IDE    n  r   r    3CAN3!2 .ARROW   n  r   r     3INGLE POLARIZATION ,OW INCIDENCE   n  r   r     (IGH INCIDENCE   n  r   r     0OLARIMETRY 3TANDARD 1UAD0OL    n  r   r      &INE 1UAD0OL    n  r   r      3ELECTIVE 3INGLE 0OL-ULTI 
 The thresholds of the ind i- vidual CFAR algorithms (CFAR -parameter setting α = 1 and β > 0 because of the LOG - amplifier) cause no false alarms, meaning that the signal ampl itudes in the scenario exceed the  CFAR threshold only for targets. Thus, a criterion for the qua lity of the CFAR threshold (i.e.,  the fit of the threshold to the clutter scenario) is given by summing the threshold crossings.  These are defined as     q=s(i)−c(i) [ ] ∑  for all i with s(i) > c(i), wher e s is the scenario and c . 
  FOR AIR 
 One method for  · protecting the tube is to direct the arc-discharge currents with a device called an electro11ic  crowbar. It places a virtual short circuit across the capacitor bank to transfer the stored energy  by means of a switch which is not damaged by the momentary short-circuit conditions. The  name .is derived from the analogous action of placing a heavy conductor, like a crowbar,  directly across the capacitor bank. 
 Another important fighter category is weapon support. Missile update is the mea - surement of missile and target position, velocity and acceleration to allow statistically  independent measurements for transfer alignment, as well as missile state-of-health.  Missile update provides the latest target information and future dynamics prediction  by data link. 
 EFFICIENCY AMPLIFIER HAS BEEN A GOAL FOR TRANSMITTER ENGINEERS EVER SINCE ,EE $E&OREST AND !MBROSE &LEMING INVENTED THE FIRST ELECTRONIC AMPLIFIERSv 4HIS GOAL SEEMS TO HAVE BEEN ACHIEVED BY THE #%! GRID 
 corresponds to rc = -1-0.443~ and 0- to 11 = -0.443~ The sin 0 - sin 11, term in the expres-  sion for 11 car1 be writtetll '  sin 0 - sin Uo = sin (0 - 00) cos Oo - El - cos (0 - i)o)] sin Oo (8.11)  'Pllc second terrn on the right-hand side of Eq. (8.1 1) can be neglected when Oo is small (beam  is near broadside), so that  sin 0 - sin O0 = sin (0 - 00) cos O0 (8.12)  Using the above approximatioi~, the two angles corresponding to the 3-dB points of the  arltenrla pattern are  0.4431  hl 0.443A 0, - 0 - sin-" - 0 - NdcosOO NdcosOO  - 0.4431 - 0.443A 0- - Oo = sin - ' .- .- --- - - ... - Nri cos O0 Nti cos O0  Til£'EI.ITTRONICAI.LY STEERED PHASED ARRAYANTENNA INRADAR283 Figure8.2Sleering ofanantenna beamwith variable phaseshifters(parallel-fed array). 
 Similarly, Cases 2 to 4 show conditions where the target's speed is 0.8, 0.6, and 0.4 times the radar's speed, in which case the target can be seen clear of sidelobe clutter over a region of up to ±78.5° relative to the target's velocity vector. Again, these conditions are for an assumed collision course. As is evident, the aspect angle of the target clear of sidelobe clutter is always forward of the beam aspect. 
 Special-Purpose Reflectors. Several types of antennas are occasionally used for special purposes. One such antenna is the spherical reflector,34 which can be scanned over very wide angles with a small but fixed phase error known as spherical aberration. 
 Remote Sens. 2016 ,8, 350. [CrossRef ] 42. 
 , 
 62. D. K. 
  
 TheknownHarkercodesareshowninTable11.2.Thelongestisoflength13.Thisisa relatively lowvalueforapractical pulse-compression waveform. Whenalargerpulse­ compression ratioisdesired. someformofpseudorandom codeisusuallyused.Apopular technique isthegeneration ofalinearrecursive sequence usingashiftregisterwithfeedback. 
 111. J. Worms, “Monopulse estimation and SLC configurations,” Proc. 
 852-855, August, 1949.  52. Ruze, J.: Wide-angle Metal-plate Optics, Proc. 
 The excess noise temperature is generally less  than 50 K. 40 ·  Receiver protectors. Since the keep-alive in the TR is not usually energized when the radar is  turned off, considerably more power is needed to break down the TR than when it is energized. 
 RANGE PERFORMANCE  IT TRANSMITS A FRAME OF PULSES WITH DIFFERING LENGTHS %ACH PULSE WITHIN THE FRAME IS OPTIMIZED TO COVER A SPECIFIED RANGE BRACKET /VERALL  THE PULSE SEQUENCE COMPLETELY COVERS THE INSTRUMENTED RANGE AND ENSURES THAT THE )-/ SPECIFIED MINIMUM RANGE REQUIREMENT IS MET )N THE RECEIVER  FRAMES ARE GROUPED INTO BLOCKS CALLED BURSTS 4HE DURATION OF A  BURST IS APPROXIMATELY EQUAL TO THE TIME TAKEN FOR THE  D" POINTS OF THE ANTENNA AZIMUTH BEAM TO SWEEP PAST A POINT TARGET CONSEQUENTLY  THE NUMBER OF PULSES IN A BURST IS DIRECTLY RELATED TO THE INSTRUMENTED RANGE AND THE ANTENNA ROTATION RATE 4HE ECHOES RECEIVED DURING A BURST ARE PROCESSED BY A FILTER BANK TO EXTRACT THE RADIAL VELOCITIES OF TARGETS AND CLUTTER 7ITHIN THE DIGITAL SIGNAL PROCESSOR  DETECTION THRESHOLDS FOR EACH OF THE FILTERS WITHIN THE BANK ARE CALCULATED ADAPTIVELY  AIMING AT PROVIDING OPTIMUM CONTROL OF FALSE ALARMS WHILE MAXIMIZING CLUTTER SUPPRESSION AND TARGET DETECTION -ANUAL CONTROL OF THE THRESHOLDS IS ALSO PROVIDED TO BE COMPLIANT WITH )-/ REQUIREMENTS -ODERN  FULLY SOLID 
 CIENTLY 4HIS LACK IN HIGH PEAK POWER IS THE MAIN DISADVANTAGE OF THE SOLID 
 It is sometimes convenient to divide an array into subarrays. For example, the  AN/SPY-I AEGIS array utilizes 32 transmitting and 68 receiving subarrays of different  sizes.81 One reason for dividing the transmitting array into subarrays is to provide a dis­ tributed transmitter. In the AEGIS array a separate high-power amplifier feeds each of the 32  transmitting subarrays. 
 'Tlie noise No is measured over the linear portion of the receiver input-output  characteristic, usually at the output of tlie IF amplifier before the nonlinear second detector.  'The receiver bandwidth Bn is that of tlie IF aniplifier in most receivers. The available gain G, is  tlie ratio of the signal out So to the signal in Si, and kTo Bn is the input noise Ni in an ideal  receiver. 
 4HE RECEIVING SYSTEM IS DEFINED HERE TO EMBRACE ONLY THE RECEIVING ANTENNA ARRAY AND  THE RECEIVERS THAT CONVERT THE ANTENNA OUTPUTS TO DISCRETE TIME SERIES  USUALLY AT BASE 
 Clampitt, L. L.: Microwave Radar Tubes at Raytheon, Electronic Progress, vol. 17, no. 
 7.22  Significance of Aperture Matching  ......................  7.22  Effects of Mutual Coupling  .................................  7.23  Element Pattern  ................................................. 
 TO 
  KD2 DTK2KVII II V2V2COS        WHERE BOLD 
    OR  }[] W2% R DR 
 DOMAIN CONVOLUTION ! GENERIC TIME 
 M RESOLUTION HAVE BECOME THE NORM  WITH SYSTEMS UNDER DEVELOPMENT OR ALREADY LAUNCHED BY AT LEAST SEVEN COUNTRIES !S EXPANDED IN THE APPROPRIATE SECTIONS OF THIS CHAPTER  THE RANGE  MEASUREMENT PRECISION OF SURFACE HEIGHT CHANGE IS NOW ON THE ORDER OF  MILLIMETER PER YEAR  AS ESTABLISHED BY TWO DIFFERENT CLASSES OF %ARTH 
 (Also availahlc in ref. I.)  20. Headrick. 
 12.17.—Circuit ofgeneral-purpose receiver.&-. 464 THE RECEIVING SYSTEM—RA DAR RECEIVERS [SEC. 12.10 control. 
 (Subm~tted a  Ohio State University Dissertation), U.S. Gov. Printing Office: 1974657-0171347. 
 Thus there is no net gain  in the detectability of desired targets. The only demand on the transmitter power is that it be  great enough to cause the clutter power at the radar receiver to be large compared to receiver  noise. If otherwise, Eq. 
 58,  pp. 543-550, April, 1970.  21. 
 (b) SSN = 100.Ground Range (nmi) (b)Ground Range (nmi) (a) . Loss (dB) Frequency (MHz) or El. Angle (deg) Noise (dBW) Loss (dB) Frequency (MHz) or Ei. 
 64 INTRODUCTION TO RADAR SYSTEMS  Cumulative probability of detection. If the single scan probability of detection for a surveil-  lance radar is P,, the probability of detecting a target at least once during N scans is called the  cumulative probability of detection, and may be written  The variation of P, with range might have to be taken into account when computing PC. The  variation of range based on the cumulative probability of detection can be as the third power  rather than the more usual fourth power variation based on the single scan probability.59  The cumulative probability has sometimes been proposed as a measure of the detectabi-  lity of a radar rather than the single-scan probability of detection, which is more conservative. 
 "!3%$ 2%-/4% 3%.3).' 2!$!23   £n°Ç 3EASAT 4HE GENERALLY ACKNOWLEDGED SPACE 
 POLARIZED AND MUST TRANSMIT CIRCULAR POLARIZATION !S REVIEWED IN 3ECTION   A DUAL 
 `` 
 Hankins, T.H.; Eilek, J.A.; Jones, G. The Crab pulsar at centimetre wavelengths, II. Single pulse. 
 Stuckey, “Activity control principles for automatic tracking algorithms,” in IEEE Radar 92  Conference , 1992, pp. 86–89. 41. 
 no. 105, pp. 274-279, 1973. 
 Adm. NTIA Rept .  83–127, July 1983. 
 Themoredirective theantenna beamandthegreaterthe spacing between antennas, thegreaterwillbethe'isolation. Whentheantenna designer is restricted bythenatureoftheapplication, largeisolations maynotbepossible. Forexample, typicalisolations· between transmitting andreceiving antennas onmissiles mightbeabout 50dBatXband,70dBatKbandandaslowas20dBatLband.9Metallic baffles,aswellas absorbing material, placedbetween theantennas canprovideadditional isolation.10 Ithasbeenreported 11thatthe·isolationbetween twoX-bandhornantennas of22dB gaincanbeincreased fromanormal.value of70dBtoabout120dBbyseparating thetwo withasmoothsurfacecoveredbyasheetofradar-absorbing material andproviding screening ridgesattheedgesofthehorns.Acommonradome enclosing thetwoantennas shouldbe avoided sinceitlimitstheamountofisolation thatcanbeachieved.. 
 STATE LINEAR &-#7 SYSTEMS nTHEIR PROMISE AND THEIR PROBLEMS v IN  0ROC )%%%  )NT -IC #ONF  !TLANTA  '!    PP  n  2 - .ARAYANAN  9 8U  0 $ (OFFMEYER  AND * / #URTIS   h$ESIGN  PERFORMANCE  AND APPLICA 
 15. Power in the Antenna Sidelobes. Airborne systems are limited in their ability to reject clutter due to the power returned by the antenna sidelobes. 
 Grasso, “Improvement factor of a nonlinear MTI in point clutter,” IEEE Trans. , vol. AES-4,  November 1968. 
 (ALL     $ # 3CHLERER ED   -4) 2ADAR  .ORWOOD  -! !RTECH (OUSE  )NC    & 2 $ICKEY  *R AND - - 3ANTA h&INAL REPORT ON ANTICLUTTER TECHNIQUES v 'ENERAL %LECTRIC  #OMPANY 2EPT 2%-(  -ARCH      $ " !NDERSON  h! MICROWAVE TECHNIQUE TO REDUCE PLATFORM MOTION AND SCANNING NOISE IN   AIRBORNE MOVING TARGET RADAR v )2% 7%3#/. #ONV 2EC  VOL   PT     PP n. Î°Î{  2!$!2 (!.$"//+    h&INAL ENGINEERING REPORT ON DISPLACED PHASE CENTER ANTENNA v VOL   -ARCH    VOLS    AND   !PRIL     'ENERAL %LECTRIC #OMPANY  3CHENECTADY  .9  ( 5RKOWITZ  h4HE EFFECT OF ANTENNA PATTERNS ON PERFORMANCE OF DUAL ANTENNA RADAR MOVING TARGET  INDICATORS v )%%% 4RANS  VOL !.% 
 tion in) Aural detection (see Detection, aural) Automatic frequency control, 453457 (See .2s. AFC) Autosyns, 487 Azimuth-pulse removal, 695 B Back-bias, 459 Back bombardment ofmagnetron cath- ode (see Magnetron cathode, back bombardment of)Back-of-the-dish system (see System, back-of-the-dish) Baltzer, O.J.,80 Bandwidth, i-famplifier, 444 over-all, of cascaded double-tuned circuits, 448 ofcascaded single-tuned stages, 446 ofreceiver (see Receiver bandwidth) Bartelink, E.H.B.,449 Beacon, airborne, 246 azimuth width ofreply of,256 choice offrequency for, 260 fixed ground, 248 with ground radar, 609 interrogation of,252–260 interrogation coding of,263–264 frequency, 263 pulse length, 263 multiple pukes, 263 two-frequency interrogation, 264 overinterrogation of,265 portable, 249 radar, 27,243–270 general description of,243–246 useforcommunication, 244, 264 range performance of,254 reply coding of,264 gap coding, 264 range coding, 264 width coding, 264 side-lobe interrogation of,257 swept-frequency, 262 traffic capacity of,265–268 unsynchronized replies of,268 Beacon system, radar, 24&254 Beam shape, choice of,60@604 Beamwidth ofantenna, 20,271 Bell Telephone Laboratories, 291, 565, 664 Bendix Aviation, 578, 580 Blackmer, L.L,,221 Blind speeds, choice of,654 iuMT1, 650 Blocklng oscillator, 502 Boice, W.K., 560 Breit, G., 13 British Technical Mission, 15 Brush, high-altitude, for rotating ma- chines, 561 B-scope, 171 design of,52&532. B-scope, electrostatic, 528 magnetic, 528 Button, C.T.,578 c Cable, coaxial, 397 Carlson, J.F.,65 Cathode follower, 494 Cathode-ray tube, 47S486 deflection coil of,477 display projection of,219 electrostatic deflection of,476 electrostatic focusing of,476 magnetic deflection of,477 magnetic focusing of,476 types of,483 Cathode-ray tube screens, 479-483 cascade, 480 dark trace, 483 long-persistence, 480 supernormal buildup in,482 Cathode-ray tube swe~ps, delayed, 522 Cavities, resonant, 405-407 CH (see Home Chain) Chaff, 82 Chain, Home (see Home Chain, British) Channel, signal, 434 Chart projector, 215 Chokes, 397 Chu, L,J,,64 Circuit efficiency, ofmagnetron, 345 Cities, radar signals from, 101 Clamps, 503-508 switched, 505–508 Close control, 232–240 Clutter, 124–126 rain, 81 Clutter fluctuation, internal, 642–644 measured values of,643 when radar ismoving, 657 Clutter-noise, 651 CMH, 188 Coaxial-type mixer, 417 Coder, triple-pulse, 686 Coding (see Beacon, interrogation coding of) effectiveness of,688 ofpulses, 686 Coherence, ways ofproducing, between echo signals and reference signal, 635-638739 INDEX Coherent oscillator, 632 effect ofdetnning, 640 forMTI, 662-665 circuit design of,663 Combined plan and height systems, 192 Complex targets, 73,7$81 Component, r-f(see R-f components) Compound targets, 73,81 Computers, dead-reckoning, 215 Conical scan (se. 
 BORS  IS THE BEST OVERALL MEASURE OF ARRAY PERFORMANCE OTHER THAN THE FULL ARRAY ITSELF )F A LARGE REFLECTION OCCURS AT SOME ANGLE OF SCAN  IT CAN BE RECOGNIZED BY A NULL IN THE ELEMENT PATTERN 4HE SMALL ARRAY CAN ALSO PROVIDE DATA ON THE COUPLING BETWEEN ELEMENTS 4HIS DATA CAN BE USED TO CALCULATE THE VARIATION IN IMPEDANCE AS THE ARRAY IS SCANNED "OTH THESE TECHNIQUES WILL BE DISCUSSED LATER IN THIS SECTION %FFECTS OF -UTUAL #OUPLING  7HEN TWO ANTENNAS OR ELEMENTS  ARE WIDELY SEPA 
 With antennas that do not scan, the mismatch may often be tuned out by conventional techniques, prefer- ably at a point as close to the source of the mismatch as possible. In a scanning array the impedance of a radiating element varies as the array is scanned, and the matching problem is considerably more complicated. Unlike a conventional antenna, where mismatch affects only the level of the power radi- ated and not the shape of the pattern, spurious lobes in the scanning array may appear as a consequence of the mismatch. 
 For two-delay cancelers, the stagger limitation is often  comparable with the basic canceler capability without staggering. For three-delay  cancelers, the stagger limitation usually predominates. Consider the transmitter pulse train and the canceler configurations shown in  Figure 2.44. 
 The SCR-584 could control an antiaircraft battery without the necessity for  searchlights or optical angle tracking,  In 1939 the Army developed the SCR-270, a long-range radar for early warning. The attack  on Pearl Harbor in December, 1941, was detected by an SCR-270, one of six in Hawaii at the  time.' (There were also 16 SCR-268s assigned to units in Honolulu.) But unfortunately, the  true significance of the blips on the scope was not realized until after the bombs had fallen. A  modified SCR-270 was also the first radar to detect echoes\ from the moon in 1946. 
       
 These tubes were triodes or tetrodes  designed lo minimize the transit-time effects and other problems of operating at VHF and  UHF. 21 The potential applied to the control grid of the tube acts as a gate, or valve, to control  the number of electrons traveling from the cathode to the anode, or plate. The variation of  potential applied to the grid is imparted to the current traveling to the anode. 
 15.24  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 15 The production of sea clutter by rain falling on a “calm” surface in the absence  of wind was also investigated by Hansen, with the results shown in Figure 15.17.69  A high-resolution X-band radar (40-ns pulse, 1° beamwidth), operating at a grazing  angle of about 3°, viewed the backscatter from a fixed spot on the windless surface of  Chesapeake Bay as the rain steadily increased from 0 to 6 mm/h. The cross sections for  vertical and horizontal polarizations were quite different for low rain rates but tended  to merge at a rain rate of about 6 mm/h. The magnitude of this splash  cross section rose  to a s  0 of about –40 dB, corresponding to highly averaged wind-induced cross sec - tions at this grazing angle for winds of about 10 kt. 
 Notilit, R. S.: Reliability without Redundancy from a Radar Monopulse Receiver, Microwaves, vol. 6,  pp. 
 The ferrite diode limiter has fast recovery time (can be as low as several tens  of nanoseconds), and if the power rating is not exceeded, the life should be essentially un-  limited. The spike and flat leakage is low, but the insertion loss is usually higher and the  package is generally longer and heavier than other receiver protectors. Except for the initial  spike, the ferrite limiter is an absorptive device as compared to the gas-tube TR or the  TR-limiter which are reflective. 
 8.5 MTI Radar (Moving Target Indication)   Moved or shifted targets can be detected in many ways and with many methods and partic u- larly due to:   - Doppler shift  - Range change from scan to scan   - Direction change from scan to scan     At first glance it is not therefore so necessary to integrate the elaborate Doppler signal p roc- essing.  In practice is it however so that the echoes from moved targets are not received alone,  but are rather surrounded by clutter, the echoes of all the reflecting objects found in the resol u- tion region.  This clutter mostly masks the echoes of move d objects. 
 Phaseinspace.Thistechniqueemploys asinglerellector witharatheruniquetypeoffeed.The effectofmultiple beamsisgenerated withthisfeed.butonlytworeceivers plusaphasedetector areneededtodetermine angular 10cation.3.\ 35Inordertoobtainwidecoverage inelevalion angleaparabolic-torus reflector isemployed ratherthanasectionofaparaboloid. Acurved pieceofwaveguide withradiating slotsactsasthefeed.Thetransmitter isfedintooneendof thewaveguide feedwhoseslotsarcdesigned toproduce anumber ofcontiguous beamsin elevation withamplitudes controlled soa~toproduce acosecant-squared radiation pattern. Onreception. 
 SIGHT ,/3  CONSTRAINTS  WHERE THE ,/3 IS DEFINED AS A LINE BETWEEN TRANSMIT AND RECEIVE ANTENNAS TANGENT TO THE %ARTHS SURFACE 3PECIFICALLY  FOR A GIVEN TARGET  TRANSMITTER AND RECEIVER ALTITUDES  THE TARGET MUST SIMULTANEOUSLY BE WITHIN ,/3 TO BOTH THE TRANSMITTER AND RECEIVER SITES &OR A SMOOTH   %ARTH MODEL  THE ,/3 RANGE R 2 BETWEEN A RECEIVE ANTENNA OF ALTITUDE H2 AND TARGET OF ALTITUDE HT IS   R2    H2   HT     WHERE ALL UNITS ARE IN KILOMETERS 3IMILARLY  THE ,/3 RANGE  R4 BETWEEN A TRANSMIT  ANTENNA OF ALTITUDE H4 AND TARGET OF ALTITUDE HT IS   R4    H4   HT     4HUS  TO PREVENT ,/3 TRUNCATION OF THE OVALS   R2 q 22MAX  AND R4 q 24MAX  4HESE  EXPRESSIONS IGNORE BOTH DIFFRACTION AND MULTIPATH  WHICH CAN SIGNIFICANTLY ALTER THESE RANGES  SO THEY MUST BE CONSIDERED FIRST 
 Delays and errors unavoidable inacomplicated scheme oftelling and plotting arelargely eliminated inasystem that combines theoperational organization with the radar equipment. Controllers who give instruc- tions toaircraft are able towork directly from the radar display and therefore have afarmore accurate and up-to-date appreciation ofthe situation than can beobtained from aplot, however well maintained it may be. This was eventually appreciated, and such systems have been put into very successful operation. 
 ,J Thereareotherfactorsbesidethenoisefigurewhichcaninfluence theselection ofa receiver front-end. Cost,burnout, anddynamic rangemustalsobeconsidered. Theselection of aparticular typeofreceiver front-end mightalsobeinfluenced byitsinstantaneous band­ width,tuningrange,phaseandamplitude stability, andanyspecialrequirements forcooling. 
 WIND DIRECTIONS  CAN ACCOUNT FOR THE OBSERVED BEHAVIOR OF THIS VERY LOW 
 VIII At the same time as the development of ASV Mk. X, the 3 cm AN/APS-3 was alsomade available. This was a forward-looking ASV and was mainly ﬁtted to Catalinas of Coastal Command as ASV Mk. 
 / 
 The use of radar for ballistic missile defense has been of interest ever since the  threat of ballistic missiles arose in the late 1950s. The longer ranges, high supersonic  speeds, and the smaller target size of ballistic missiles make the problem challenging.  There is no natural clutter problem in space as there is for defense against aircraft,  but ballistic missiles can appear in the presence of a large number of extraneous con - fusion targets and other countermeasures that an attacker can launch to accompany  the reentry vehicle carrying a warhead. 
 Somewhat higher transmitter power will beavailable atthelonger wavelengths. Atthetime ofthedevelopment described, perform- ance ofexisting components was better inthe 10-cm region than atany other wavelength suitable forthis application. 15.10. 
 MATION IS TYPICALLY REQUIRED FOR MANY LARGE APERTURES 4HE TRANSFORMATIONS CAN RANGE FROM SIMPLE COLUMN BEAMFORMING TO OVERLAPPED SUBARRAYS TO BEAM 
 G. V . Trunk and J. 
 With FM -CW Radar the duration  will be determined from the difference in frequency as received from the target and of the current  transmitter.  For the simple case of linear frequency modulation, referring to Figure 4.1, ∆ t is as fo l- lows:  € Δt=ΔfT B⇒R=ΔfT 2Boc (4.2)  Along with the analysis of the frequency difference ∆ f, with FM -CW Radar the range to reflecting  objects can also be calculated from a Fourier transform of the complex frequency signal in the time  domain.   The unambiguous range of coverage is limited by th e pulse repetition frequency PRF  = 1/Τ of the  selection. 
 148.Brennan, L.E.,I.S.Reed,andP.Swerling: Adaptive Arrays,Microware J.,vol.17,pp.4346,p.74, May,1974. 149.O'Donovan, P.L.,andA.W.Rudge:Adaptive Control ofaFlexible LinearArray,Electronin Letters,vol.9,pp.121-122, Mar.22,1973. 150.Gabriel, W.F.:Adaptive Arrays-An Introduction, Proc.IEEE,vol.64,pp.239-272, February, 1976. 
 BER OF ZEROS CAN BE ALLOCATED DYNAMICALLY TO EITHER CLUTTER SOURCE AS A FUNCTION OF RANGE 4HIS LEADS TO A FULLY ADAPTIVE -4) IMPLEMENTATION USING A MORE COMPLEX ADAPTATION ALGORITHM  AS DISCUSSED BELOW 3UCH AN ADAPTIVE -4) MAY PROVIDE A PERFORMANCE CLOSE TO THE OPTIMUM DISCUSSED IN 3ECTION  )N ORDER TO ILLUSTRATE THE DIFFERENCE IN PERFORMANCE BETWEEN SUCH CANDIDATE -4)  IMPLEMENTATIONS  A SPECIFIC EXAMPLE IS CONSIDERED NEXT &OR THIS EXAMPLE  LAND CLUTTER RETURNS ARE PRESENT AT ZERO DOPPLER WITH A NORMALIZED SPECTRAL SPREAD OF  R F4     AND  CHAFF RETURNS ARE PRESENT AT A NORMALIZED DOPPLER OFFSET OF  FD4    WITH A NORMALIZED  SPECTRAL SPREAD OF  RF4    4HE POWER RATIO OF THE LAND CLUTTER TO THAT OF THE CHAFF  IS  DENOTED 1 D"  4HERMAL NOISE IS NOT CONSIDERED IN THIS EXAMPLE )N BOTH CASES  THE  TOTAL NUMBER OF FILTER ZEROS IS ASSUMED TO BE EQUAL TO  &OR THE ADAPTIVE -4) WITH A FIXED ALLOCATION OF ZEROS  TWO ZEROS ARE LOCATED AT ZERO DOPPLER AND THE REMAINING ZERO IS CENTERED ON THE CHAFF RETURNS )N THE OPTIMUM -4)  THE ZERO LOCATIONS ARE CHOSEN SO THAT THAT OVERALL IMPROVEMENT FACTOR IS MAXIMIZED 4HE RESULTS OF THIS COMPARISON ARE PRESENTED IN &IGURE   WHICH SHOWS THE IMPROVEMENT FACTOR FOR THE OPTIMUM AND THE ADAPTIVE -4) AS A FUNCTION OF THE POWER RATIO  1 D"  7HEN  1 IS SMALL SO THAT  CHAFF RETURNS DOMINATE  A SIGNIFICANT PERFORMANCE IMPROVEMENT CAN BE REALIZED BY USING ALL -4) FILTER ZEROS TO CANCEL THE CHAFF RETURNS 4HE PERFORMANCE DIFFERENCE FOR LARGE VALUES OF  1 IS A RESULT OF AN ASSUMPTION MADE THAT THE LOCATION OF THE THIRD ZERO  REMAINS FIXED AT THE CHAFF DOPPLER FREQUENCY )N REALITY  THE ADAPTIVE -4) WOULD MOVE &)'52%  /PEN 
   '2/5.$ 0%.%42!4).' 2!$!2   Ó£°ÎÇ !BANDONED ANTIPERSONNEL LAND MINES AND UNEXPLODED ORDNANCE ARE  A MAJOR HIN 
 However, ARM receiver sensitivity is affected by mismatching losses; accuracy in  locating the victim radar is affected by the limited dimension of the ARM antenna. 24.5 OBJECTIVES AND TAXONOMY   OF ECCM TECHNIQUES The primary objective of ECCM techniques when applied to a radar system is to  allow the accomplishment of the radar intended mission while countering the effects  of the enemy’s ECM. In greater detail, the benefits of using ECCM techniques may  be summarized as follows: (1) prevention of radar saturation, (2) enhancement of the  signal-to-jamming ratio, (3) discrimination of directional interference, (4) rejection of  ch24.indd   8 12/19/07   6:00:04 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 [ CrossRef ] 27. Zhang, Z.; Wang, C.; Wang, M.; Wang, Z.; Zhang, H. Surface deformation monitoring in Zhengzhou city from 2014 to 2016 using time-series insar. 
 PE-218-G PE-218-D 26 29–45 +25 +55 –45 +25 +55373 379 396 396 406 398 411 404 443 423 449 428 Over-all regulation ILeland IGECo, PE-21&C PE218-D Incps I76 Inpercent 17,0 i:.5 Alldata were taken atsealevel and with full rated load oninverter. The GE PE-218-D unit has acompensating resistor inseries with the field which accounts foritsslightly better regulation. Italso has an adjustable resist orwhich allows thefrequency tobevaried over arange ofapproximately 40cps. 
               $*            
 J. Price, A. M. 
 The two final output devices and the eight driver  devices are 100 W transistors capable of operating up to a 10% duty cycle over the   100-MHz bandwidth at collector efficiencies greater than 52%. Each module is air- cooled, and the measured efficiency is greater than 25% when the module is operating  at an 8.2% average duty cycle. Module power gain is greater than 16 dB. 
 1966.  55. Fried, W.R.: Doppler Navigation, chap. 
  - 7ITH THE PROLIFERATION OF BALLISTIC MISSILES  FUTURE SHIPBOARD  RADAR SYSTEMS WILL PROB 
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 $   
 A 9-bit A/D converter therefore has a maximum di:,cri­ mination of 1 out of 511 levels; or approximately 54 dB. (Equation (4.12) on the other hand,  predicts 52.9 dB for 9-bit quantization.)  In the above it was said that the addition of the Q channel removed the problem of  reduced sensitivity due to blind phases. This is different than the blind speeds which occur when  the pulse sampling appears at the same point in the doppler cycle at each sampling instant, as  shown in Fig. 
 -CO~PARISON OF THE Two PULSER TI-PES Characteristics Efficiency Pulse shape Impedance-matching Interpuke interval Voltage supply Change ofpulse dura- tion Time jitter Cmcuit complexity Effects ofchange in voltageHard-tube pulser Iwwer; more overhead power required fordriver, cathode heating, andfordissipation inswitch tube Better rectangular pulses l~ide range ofmismatch per- missible lIay be\-cry short, asforcod- ingbeacons (i.e.,<1psec) High-voltage supply usually necessary Easy; switching inlow-voltage circuit Somewhat easier toobtain negligible time jitter, i.e., <0.02 /see, than with line- type pulscr Greater, leading togreater difficulty inservicing Fordesign ha}-k gmaximum et%ciency, (AP/P) output = 6(AV/\’) input. Bysacri- ficing efficiency inthedesign, (AP/P) output =05(AV/~) input canbeobtainedLine-type plllser High, particularly rrben pUke- power output ishigh Poorer rectangular pulse, par- ticularly through pulse trans- former Smaller range ofmismatch per- missible (+20-30 percent). Pulse transformer ~villmatch anyload, butpower input to nonlinear load cannot be varied over awide range X[ust beseveral times the deionization time ofdischarge tube (i.e., >100psec) Low-voltage supply, particu- larly with inductance charg- ing Requires high-voltage switch- ingofnetwork High-power line-type pulsers with rotary-gap switch have inherently large time jitter. 
 Ê */6 
 CODE IN OR NEAR THE  RADAR OPERATING BAND )N SOME CASES  THE FREQUENCY CHANNEL IS RANDOMLY SELECTED AT THE FACTORY AND HARDWIRED INTO THE MISSILE &REQUENCY CHANNELS ARE TYPICALLY SELECTED OR COMMUNICATED TO THE RADAR IMMEDIATELY BEFORE LAUNCH )F THE DATA LINK FREQUENCY IS WELL BELOW THE RADAR BAND  USUALLY A SMALL NUMBER OF RADIATORS AT THAT LOWER FREQUENCY ARE IMBEDDED IN THE RADAR APERTURE )F THE FREQUENCY IS CLOSE ENOUGH TO THE RADAR BAND  THE RADAR APERTURE OR A SEGMENT OF THE APERTURE IS USED 2ADAR !PERTURE $ATALINKING  (ISTORICALLY  DATALINK FUNCTIONS EMBEDDED IN  -&!2S HAVE BEEN USED FOR THE MIDCOURSE GUIDANCE OF MISSILES !N EMERGING APPLICA 
 AXIS RADAR v IN  )NT 2ADAR #ONF 2EC     PP n.   42!#+).' 2!$!2   °{  ) $ /LIN AND & $ 1UEEN  h$YNAMIC MEASUREMENT OF RADAR C ROSS SECTION v  0ROC )%%%  VOL    PP n  !UGUST   * ( $UNN  $ $ (OWARD  AND ! - +ING  h0HENOMENA OF SCINTILLATION NOISE IN RADAR 
 30, pp. 729–737, May–June 1995. 57. 
 ISTICS OF A RADAR CAN BE EXPLOITED AS %##- TECHNIQUES IN TWO WAYS &IRST  THE CROSS 
   (& /6%2 
 65. D. K. 
 VELOCITY PRODUCT 4ABLE    THE ANTENNA AREA NEEDS TO BE ONLY  ^  M  TO SATISFY  THE MINIMUM AREA CONSTRAINT %Q   4HESE RADARS ARE INDEED LOW MASS  AT ABOUT  KG AND  KG  RESPECTIVELY  INCLUDING IN EACH CASE THEIR ANTENNA ! MAJOR OBJECTIVE FOR BOTH OF THESE RADARS IS TO LOOK FOR EVIDENCE OF ICE DEPOSITS  IN THE PERMANENTLY SHADOWED AREAS OF THE -OONS POLAR REGIONS 4HIS REQUIRES THAT THEY MUST MEASURE THE CIRCULAR POLARIZATION RATIO #02  (ENCE  THEY TRANSMIT CIRCULAR POLARIZATION  AND THEY ARE DUAL 
 CATION &IGURE  ILLUSTRATES THE MOST COMMON OF THESE REFLECTORS  EACH OF WHICH IS DESCRIBED IN SOME DETAIL IN THE FOLLOWING SUBSECTIONS 4HE PARABOLOID IN &IGURE  A  COLLIMATES RADIATION FROM A FEED AT THE FOCUS INTO A PENCIL BEAM  PROVIDING HIGH GAIN AND MINIMUM BEAMWIDTH 4HE PARABOLIC CYLINDER IN &IGURE  B PERFORMS THIS COLLIMA 
 Army has used the method extensively innavigating across the Alps. One difficulty inherent in the use ofradar pilotage over mountainous terrain isillustrated in Fig. 3-K). 
 It acts as a digital pllase sliifter if the drive currents are digital. A digital-to-analog conversion  is rcrlrlircd to transliite the digital control-signal generated by the array computer to a form  that car1 set tlic I1u.u-drive pliase sliifter. *I'lic lengtli of the toroid is generally 111ade 15 to 20  percent greater thari normal to allow for some shrinkage of the total available increment of  rnagtietizatio~i due to telnperature changes. 
 Rem. Sens. , vol. 
 , &IGURE  DEFINES THE GEOMETRY FOR BISTATIC DOPPLER WHEN THE TARGET  TRANSMITTER  AND RECEIVER ARE MOVING 4HE TARGET HAS A VELOCITY VECTOR OF MAGNITUDE  6 AND ASPECT  ANGLE C  REFERENCED TO THE BISTATIC BISECTOR 4HE TRANSMITTER AND RECEIVER HAVE VELOCITY  VECTORS OF MAGNITUDE  6 4 AND 62 AND ASPECT ANGLES  C 4 AND C 2  RESPECTIVELY  REFERENCED  TO THE NORTH COORDINATE SYSTEM OF &IGURE  !LL VECTORS ARE PROJECTIONS OF THE THREE 
 T ectonophysics 2016 ,691, 271–281. [ CrossRef ] 9. Garcia, A.J.; Bakon, M.; Martinez, R.; Marchamalo, M. 
 The other region of interest is that which lies just  heyond the interference region below the radar line of sight and is the diffraction. or the  shadow. region. 
 The improvement factor of a noncoherent MTI will not, in general, be as good as can be  obtained with a coherent MTI tliat employs a reference oscillator (coho). The reference signal  in the noncoherent case is tlie clutter itself, which will not be as stable as a reference oscillator  because of tlie finite width of the clutter spectrum caused by its own internal motions. If a  nonlinear IF ariiplifier is used, it will also limit the improvement factor that can be achieved. 
 9 of" Mechanical Engineering in Radar and Communications," C.  J. Richards (ed.). 
 The  significant difference between this MTI configuration and that of Fig. 4. lh is the manner in  which the reference signal is generated. 
 ¤ ¦¥³ µ´ 
 4.2.2 Modulator type 158 This was similar to modulator type 64 used on ASV Mk. III, but with an increased power output of 550 kW peak. A bridge recti ﬁer generated a DC power supply of 7 kW and from this pules of 1 μs duration and recurrence frequency 666 c/s were formed using a CV125 spark gap and a DN39C delay line. 
 The radial velocity components of the three system ele- ments contribute to the doppler shift of the re- ceived signal.TARGET MISSILE . It should also be clarified what is meant by approaching and receding tar- gets within the missile doppler spectrum. A target approaching the missile will yield a signal at a frequency above that of MLC (which corresponds to missile velocity). 
 98. R. J. 
 ,  104. Wickenden, B. V. 
 GULAR  AND THE DIFFERENCE IN RANGE ACROSS A RESOLUTION ELEMENT  IS NEGLIGIBLE  THE EXPRES 
 Weil and Merrill Skolnik 10.1 INTRODUCTION Role of the Transmitter in Radar.  If a radar systems designer could ask for  anything he or she wanted in a radar transmitter, that wish might be something like  the following: Provide the necessary transmitted energy with the needed average and peak  power, as well as the required stability and low noise for good doppler process - ing; operate with high efficiency; have wide bandwidth and be easily tunable;  be readily modulated in amplitude, frequency, or phase as necessary; have high  reliability and long life; require minimum maintenance; have no dangerous X-ray  emissions; require no personnel to operate; be of an affordable price; and be of  reasonable size and weight for the desired application. Of course, not all of these desirable attributes can be achieved in any given radar trans - mitter application. 
 l)  It is assumed in this analysis that the lengths of the direct and the reflected paths are almost  (but not quite) equal so that the amplitudes of the two signals are approximately the same  provided there is no loss suffered on reflection. Hence, if the amplitudes of the two waves differ  from one another, it is assumed to be due to a surface-reflection coefficient less than unity.  Although the two paths are comparable in length, they are not exactly equal. 
 Uhlenheck (eds.): "Threshold Signals," MIT Radiation Laboratory Series.  vol. 24, McGraw-Ilill Book Company, New York, 1950, p. 
 However, note a few echo sources along a line  parallel to, and slightly forward of, the wing trailing edges. If the target rotation had  been centered on an aspect angle perpendicular to one of the wings, the leading edge  of that one wing would have “lit up.” In the region of the main wing roots, we see heavy concentrations of echo sources.  Some of them lie forward of any wing surface. 
 DOPPLER CLUTTER IS USED TO COVER ALL THESE  PHENOMENA WHERE THE SCATTERERS RESPONSIBLE FOR THE CLUTTER DO NOT HAVE A WELL 
 All rights reserved. Any use is subject to the Terms of Use as given at the website. Radar Receivers.  RADAR RECEIVERS  6.176x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 6 Figure 6.5 illustrates typical common and uncommon phase noise components and the  resulting mixer output phase noise as calculated using  L f L f F f L fC R U '() ( ) | ( )| ( ) = +2 (6.10) where  LC(f) = STALO SSB phase noise spectrum common to the receiver and exciter  LU(f) = total receiver-exciter uncorrelated STALO SSB phase noise  FR(f) = range dependence factor Residue Power and MTI Improvement Factor. 
 The/requency response function is proportional to sin2 nh T.  A transversal filter with three delay lines whose weights are 1, -3, 3, -I gives a sin 3 nf, T  response. This is a four-pulse'canceler. 
 Two prototype installations on Wellington VIII aircraft were completed at No. 30 MU in December 1942 and the CCDU work on assessing ASV Mk. III started in January 1943.Airborne Maritime Surveillance Radar, Volume 1 3-3. 
 164.  J. Wurman and M. 
 The motion compensation mainly compensates for the translation motion between the target and the radar. It contains two steps, one is range alignment, and the other is phase compensation [ 8,11]. The raw data-like data R(m,n)is inverted from SLC SAR images and range alignment is a coarse compensation, the raw data-like data R(m,n)no longer implement range alignment and the phase compensation is the main step of ISAR processing in this paper. 
 1111. 1.1 I ( IRONl('A1 I Y Sll~l~l~I~l~ I~IIASI~I~ ARRAY ANI'ICNNA IN RAl)Al< 339  42. Sakiotis, N. 
 Sensors 2019 ,19, 743 36. Chen, G.; Zhang, Y.; Zeng, R.Q.; Yang, Z.K.; Chen, X.; Zhao, F.M.; Meng, X.M. Detection of land subsidence associated with land creation and rapid urbanization in the chinese loess plateau using time series insar: A case study of Lanzhou new district. 
 " AMPLIFIERS ARE BIASED SUCH THAT CONDUCTING CURRENT IN THE TRANSISTOR FLOWS FOR EXACTLY ONE HALF OF THE INPUT SIGNAL VOLTAGE SWING 0USH 
 This vision may now b e- come possible and extend far beyond what was previously imagined.  Synthetic aperture Radar is  an especially a ppropriate candidate to explain and demonstrate the future.   14.1 The Transmit Subsystem   Currently transmit subsystems are mainly implemented using one of the following princ iples:  Pulsed- FM synthesizer -  high power amplifier - reflector antenna   Pulsed- FM synthesizer -  high power amplifier - beam forming network -  fixed array  Pulsed- FM synthesizer -  feed network -  transmit/receive modules - radiating el ements  The first two of these alternatives are completely inflexible. 
 For this terrain, it was concluded that$ a minimum  clutter patch separation of 75 m (0.5 ps) were necessary for target tracking, a 10 m2 target  could be tracked 99 percent of the time, but a 1 m2 target could be tracked only 55 percent of  the time.  In the above example of C-band data, the echoes from man-made objects were "point"  targets of radar cross sections greater than 10 mZ. At the lower microwave frequencies, the  echoes from the strong point-scatterers can be several orders of magnitude greater. 
 #+** ( #+ *+*!&%  (&&$      "   /%$!  %   *   )  &!) &- (  ( !%%*  (*  !) ( *  , #* 
 The first is ship detection, where the intrinsic  doppler spread of sea clutter routinely extends beyond the typical doppler shifts of  most ship echoes. The second case is the phenomenon of spread doppler clutter,  which arises from plasma instabilities and turbulence, especially post-sunset and  at high and low latitudes. The equivalent velocity of this type of clutter can extend  to hundreds of meters per second, masking even fast aircraft returns. 
 Summary of errors. The contributions of the various factors affecting the tracking error  are summarized in Fig. 5.14. 
 ENT MICROWAVE RADAR v IN  7AVE $YNAMICS AND 2ADIO 0ROBING OF THE /CEAN 3URFACE  CHAP     / - 0HILLIPS AND + (ASSELMANN EDS   .EW 9ORK 0LENUM 0RESS    PP n  2 + -OORE  9 3 9U  ! + &UNG  $ +ANEKO  ' * $OME  AND 2 % 7ERP  h0RELIMINARY STUDY  OF RAIN EFFECTS ON RADAR SCATTERING FROM WATER SURFACES v  )%%% * /CEANIC %NG   VOL /% 
 PLER PROCESSING IS IMPORTANT !N EXAMPLE OF A HIGH POWER GYROKLYSTRON FOR RADAR APPLICATIONS IS THE 6'" 
 CHAPTER  TEN  DETECTION OF RADAR SIGNALS IN NOISE  10.1 INTROOUCflON  The two basic operations performed by radar are ( 1) detection of the presence of reflecting  objects, and (2) extraction of information from the received waveform to obtain such target  data as position, velocity, and perhaps size. The operations of detection and extraction may be  performed separately and in either order, although a radar that is a good detection device is  usually a good radar for extracting information, and vice versa. In this chapter some aspects of  the problem of detecting radar signals in the presence of noise will be considered. 
 Therefore, motion compensation is required in data processing. In the mode of multi-ﬂight acquisition for imaging data, the motion compensation of each SAR image is different because of the different motion errors of each ﬂight, which brings difﬁculties to image matching. When multi-angle SAR data are taken by this system, data of each angle have the same motion error, and the data of multiple angles can be compensated by the motion error of a single view, simplifying the compensation process. 
 Finally, the chapter concludes with a discussion of sensor integration and radar netting, including both colocated and multisite systems. 8.2 AUTOMATICDETECTION The statistical framework necessary for the development of automatic detection was applied to radar in the 1940s by Marcum,1 and later Swelling2 extended the work to fluctuating targets. They investigated many of the statistical problems . 
 Schelleng, J. C., C. R. 
 The multipath bias errors dominate the total accuracy performance of the monopulse technique and, contrary to the behavior of the thermal errors, are not suppressed by high target signal-to-noise ratios. By . NORMALIZED ANGLE ESTIMATION BIASERROR (U-SPACE)£u = L/XSIN £e -NORMALIZED ANGLE ESTIMATION BIASERROR (U-SPACE)60 = LASIN (€e) *- NORMALIZED MONOPULSESENSITIVITY FACTORK'= K-X/L •*NORMALIZED MONOPULSESENSITIVITY FACTORK' = K-X/L - FIG. 
 Insome cases theheight-finding antenna search] ights inazimuth and ismanually aimed inthe proper direction. Ifitscans inazimuth, thecenter ofthesector which isshown ontheRHI isindicated byamechanical cursor onthe PPI ofthesearch set. TheE-scope.—The E-scope isarectangular display inwhich range +20 .s() c0 “%-10~ El -20Ground echoes -60-300+30+60 Arimuth indegrees FIG.6.11.—C-scope.isthe x-coordinate and elevation angle the y-coordinate. 
 No other sensor can  measure the distance to a remote target at long range with the accuracy of radar (basically  limited at long ranges by the accuracy of the knowledge of the velocity of propagation).  At modest ranges, the precision can be a few centimeters. To measure range, some sort  of timing mark  must be introduced on the transmitted waveform. 
 TIGATORS PROCESS THEIR DATA TO PROVIDE THE  MEAN VALUE  AND BECAUSE THE CONVERSION  OF A MEDIAN TO A  MEAN REQUIRES KNOWLEDGE OF THE PROBABILITY DISTRIBUTION FUNCTION   CARE MUST BE TAKEN TO AVOID AMBIGUITY IN COMPARING THE MEASUREMENTS OF DIFFERENT EXPERIMENTERS 4HE ORIGINAL ANALYSIS OF THE .2, &2 DATA WAS BASED ON  MEDIAN  CROSS SECTIONS AND THE ASSUMPTIONS OF THE COOKIE 
 In the spring of 1937 it was installed and tested on  the destroyer Leary. The range of the 200-MHz radar was limited by the transmitter. The  development of higher-powered tubes by the Eitel-McCullough Corporation allowed an  improved design of the 200-MHz radar known as XAF. 
 Golay, M. J.E.: Complementary Series, IRE Trans., vol. IT-7, pp. 
 2/4(2 .OSTRADAMUS3TEEL 9ARD+OMSOMOLSK NA !MUR  $EVELOPER $34/   !USTRALIA4ELECOM !USTRALIA'%# 
 Just as the second-hand of a  clock completes the sweep of the dial in sixty seconds,  ticking its way around the chapter ring, so the pencil of  electrons in the tube can be made to trace a pattern in  any interval of time. We cannot swing the hands of a  clock much faster than, say, one tick every second,  becanse there is inertia, and even the most carefully  balanced clock hands have an effective mass. But there  § RO Weight in the pencil of electrons, no lag, and so  the beam can be swung backward and forward with the  ‘Speed of ight. 
 No zero padding was used in this procedure in the Range Doppler focusing software, while in the proposed algorithm the zero padding was used both in range and azimuth directions to avoid the circular convolution distortion. This reduces the amplitudes of large portions of the image, giving rise to a lower standard deviation and in the normalization a higher factor. This higher factor enhances very much the point scatterer that appears larger on the image, but the range and azimuth cuts in Figures 9and 10allow a better comparison of the performances. 
 SOURCE ANTENNAS FOR NARROW BEAMWIDTH AND LOW SIDELOBES v  )2%  4RANS  VOL !0 
 51. C. J. 
 45 -50, February, 1959.  8. Lawson, J. 
 ISOTROPIC SEA DIRECTIONAL SPECTRUM  THE VALUE OF  R VVn WAS CALCULATED AS n D" THE MEASURED VALUES WERE GROUPED  BETWEEN  
 Senior. T. H. 
 Attheseheightstherecan appearattimespatchesofhigh-density ionization calledsporadic Ewhich,whenavailable, canbequiteeffective inproviding stablepropagation. Themultiple refracting regionsgiverise tomultipath propagation whichcanresultindegraded performance because ofthesimulta­ neousarrivalofradarenergyatthetargetviamorethanonepropagation path,eachwith different timedelays.Theeffectsofmultipath canbereduced bytheproperselection of frequency andbyuseofnarrowelevation beamwidths whichallowtheenergytotraveltothe targetviaonlyasinglepath.Thepresence ofthevarious refracting rcgions withdiffcrcnt ionization densities atdifferent altitudes requires goodfrequency managcmcnt ifanOTH radaristooperate withreliability. Theminimum rangetowhich'HFlenergy canbepropagated byionospheric refraction is determined bythelowestfrequency atwhichtheradarcanoperate. 
 Hence"dividestheradiation patternintoa uniform sidelobc regionstraddling themainbeamandadecreasing sidelobe region.The numher of~cqual sidelobes oneachsideofthemainbeamis"-1. Thcbeamwidth ofaTaylorpatternwillbebroader thanthatoftheDolph-Chebyshev. If thedesignsidelobe levelis25dB,aTaylorpatternwith"=5givesabeamwidth 7.7percent greaterthantheDolph-Chehyshcv, andwith"=8itis5.5percentgreater. 
 Gawronski, M. J., and H. Goldie: 200 W MIC L-Band Receiver Protector, Microwave J., vol. 
 In particular, operating at higher altitudes increased the range of the sea returns, so reducing the swept area of search. Minimum ranges varied from less than ½ mile to more than 4 miles, dependent on sea conditions and aircraft height. Reports describing the installation of ASV Mk. 
 2.29 as a function of the collapsing ratio  (111 + 11)irl. The difference between tile two cases can be large. As the nurnber of hits ri iricreases,  the difference becomes smaller. 
 Safaeinili,  D. A. Gurnett, R. 
   PP n    $ 4 3ANDWELL  h!NTARCTIC MARINE GRAVITY FIELD FROM HIGH 
 Bales. R. 11. 
 Nc)11rcci1)roci~I  phase shifters cannot be t~.cd in reflectarrays (Sec. 8.6). since the electromagnetic energy must  travel in both directions. 
 Elevated ducts may  vary from a few hundred meters above the surface at the eastern part of the tropical  oceans to several thousand meters at the western part. For example, along the southern  California coast, elevated ducts occur an average of 40% of the time, with an average  top elevation of 600 meters. Along the coast of Japan, elevated ducts occur an average  of 10% of the time, with an average top elevation of 1500 meters. 
 The Pulse Repetition Interval (PRI) is the time the pulse cycle  takes before repeating. It is equal to the reciprocal of the PRF  or Pulse Repetition Rate (PRR), the number of transmitted  pulses per second. PRI is important because it determines  the  maximum unambiguous range or  distance of the radar. 
 NOISE RATIO REPRESENTS THE MEAN VALUE OF THIS PROCESS OVER TIME &IGURE  ASSUMES A PENCIL 
 Excessive false alarms in an ADT system cause the computer to overload as it  attempts to associate false alarms with established tracks or to generate new, but false, tracks.  Manual control is too slow and imprecise for automatic systems. Some automatic, instanta-  neous means is required to maintain a constant false-alarm rate. 
 D. D. Crombie, “Doppler spectrum of the sea echo at 13.56 Mcs,” Nature, vol. 
 For example, for a gaussian-shaped  clutter spectrum we have  S f Pf f C C fd f( ) exp( )= ⋅ ⋅⋅ −− ⋅  1 2 22 2π σ σ (2.30) where PC is the total clutter power, sf is the standard deviation of the clutter spectral  width, and fd is the average doppler shift of the clutter. The corresponding autocor - relation function is  R P j fC C f d ( ) exp ( ) exp( ) τ πσ τ π τ = − − 4 22 2  (2.31) where t  is the separation in time of two consecutive clutter returns.FIGURE 2.22  MTI improvement factor as a function of the rms velocity spread of clutter for   a four-pulse binomial-weight canceler  ch02.indd   27 12/20/07   1:44:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
 4.lh and the one described in  Chap. 1 is that a small portion of the CW oscillator power that generates the transmitted  pulses is diverted to the receiv'er to take the place of the local oscillator. However, this CW  signal does more than function as a replacement for the local oscillator. 
 41. Barab, J. D., J. 
 1.3 INFORMATION AVAILABLE FROM THE RADAR ECHO Although the name radar is derived from radio detection and ranging, a radar is capable of providing more information about the target than is implied by its name. Detection of a target signifies the discovery of its presence. It is pos- sible to consider detection independently of the process of information extrac- tion, but it is not often that one is interested in knowing only that a target is . 
 This isknown asasingle-tuned stage, since there isone tuning inductance per stage. Ithas the advantage ofbeing simple, easy to manufacture and align, and noncritical inadjustment. Itisparticularly useful ini-famplifiers ofover-all bandwidth less than 3Mc/see. 
 L. Mensa, High Resolution Radar Imaging , Norwood, MA: Artech House, 1981. 67. 
 92-97, February, 1946.  63. Mumford, W. 
 The signal suffers attenuation as it passes through the duplexer. Generally, the greater the  isolatio~l required from the duplexer 011 transmission, the larger will be the insertion loss. By  inscrtio~i loss is rneant tlie loss itltr-oduced when the component. 
 P. Wu, “Radiation properties of large planar arrays,” Bell Teleph.  Syst. 
 _’ But across the Y plates we have to place our signal  ~ voltage, which even with most efficient radar amplifiers  _ may still be very small compared with the time-base  '- voltage on the X plates. Thus the sensitivity of the tube  ‘in the Y direction needs to be considerably higher than  sin the X direction. This involves important construc-  tional considerations inside the tube, and the Y plates  may be placed much closer together than the X plates. 
 Aeronaut. Astronaut. 1995 ,12, 195–201. 
 How- ever, if sidelobes are a prime consider- ation, a somewhat different feed size may be desired. The limitation of the four-horn square feed is that the sum- and difference-signal E fields cannot be con- trolled independently. If independent control could be provided, the ideal would be approximately as described in Fig. 
 WAVE DEVICE IS DETERMINED BY THE CIRCUIT DIMENSIONS !N ELECTRON IN AN APPLIED AXIAL MAGNETIC FIELD  " O WILL ROTATE AT  WHAT IS CALLED THE  ELECTRON CYCLOTRON FREQUENCY   WHICH IS GIVEN BY  VC   E"OMG  WHERE  E   ELECTRON CHARGE   M   ELECTRON REST MASS  AND  G IS THE RELATIVISTIC FACTOR  WHICH IS   ;   EMC 6O=  WHERE C   VELOCITY OF LIGHT AND  6O   BEAM VOLTAGE 4HE BEAM VOLTAGE  AND THE CORRESPONDING ELECTRON VELOCITY  IN A GYROTRON ARE HIGH ENOUGH TO CAUSE RELATIV 
 TIME EFFECTS  WHICH  LIMIT THE HIGH FREQUENCY PERFORMANCE OF GRID 
 several different ways. On*that oftelling grid coordinates ofatarget toplotters who enter thetarget position onalarge board—will bedescribed inSees. 7”5and 7.6. 
 11.5) can  overcome this limitation of a short pulse since it can achieve a resolution equivalent to that of  a short pulse, but with tlic energy of a long pulse. Second, the required signal-to-clutter ratio  depends on the pulse width because of the change in clutter statistics (probability density  RADAR CLUTTER 483 sidelobes. Inthiscase,whenstronglandclutterisaproblem, agoodMTIorpulse-doppler radarisrequired. 
 This video is typically processed by a boxcar circuit which charges a capacitor to the peak video-pulse voltage and holds the charge until the next pulse, at which time the capacitor is discharged and recharged to the new pulse level. With moderate low-pass filtering, this gives a dc error voltage output employed by the servo am- plifiers to correct the antenna position. The three-channel amplitude-comparison monopulse tracking radar is the most commonly used monopulse system. 
 One new material ofinterest isAlsifilm orDiaplex, analuminum-silicate clay inanorganic impregnate. This material can beformed into thin, homogeneous sheets which have dielectric properties superior tomica orpaper and oil. The— Diameter t—nl — /d ~lG. 
 Asbeck, S. Cripps, P. B. 
 Theory T ech. 2017 ,65, 293–301. [ CrossRef ] 24. 
 The prf must be high enough to avoid  angle ambiguities and image-foldover that results from grating lobes produced when the  spacing between the elements of the synthetic array is too large. These two conflicting require­ ments on the prf of a SAR mean that the resolution and the coverage (swath) cannot be  selected independently.  To avoid grating lobes in a phased-array antenna of isotropic radiating elements (with  the main beam perpendicular to the aperture), the element spacing must be less than the  wavelength A. 
 PULSE INTERLEAVING  TRANSMITRECEIVE FIRST ((  THEN (6  THEN 6(  AND THEN 66 DATA  AND PRODUCE FOUR CORRESPONDING SIMULTANE 
 16.29. Output signals from several successive i-fstages arecombined. Atlow signal levels, thelast stage delivers alinear signal inthenormal fashion, theoutput from thepreceding stages being negligible. 
 Attwood, Radio Wave Propagation, Consolidated Summary Technical  Report of the Committee on Propagation, NDRC , New York: Academic Press, 1949, p. 219. 52. 
 Although one parabolic bend CC would serve to collimate the primmy radiation and provide asharp beam onaxis, two bends may besodesigned astocorrect forcoma and thus give agood beam offaxis aswell. The theory oftwo-mirror telescopes was used to calculate the bends for the Schwarzschild antenna. The cylindrical. 
 NOISE RATIO EXCEEDS THE SIGNAL 
 423–43, July 1964. 51. W. 
   '2/5.$ 0%.%42!4).' 2!$!2   Ó£°Ç  DS   LOW FREQUENCY LIMITING VALUE OF THE PERMITTIVITY  V     RADIAN FREQUENCY   O  F     S     RELAXATION TIME CONSTANT 4HE FREQUENCY OF MAXIMUM MOVEMENT AND LOSS OCCURS AT V     S )N GENERAL  SINGLE RELAXATIONS ARE RARELY OBSERVED IN NATURAL SYSTEMS )NSTEAD   THERE ARE DISTRIBUTIONS OF RELAXATIONS CORRESPONDING TO DISTRIBUTIONS OF SIZE SCALES  THAT INFLUENCE MOVEMENT OF CHARGE 4HERE ARE SEVERAL EQUATIONS DESCRIBING SUCH  DISTRIBUTED SYSTEMS  WITH THE MOST COMMON EXPERIMENTAL OBSERVATIONS IN AGREEMENT WITH THE MODEL FROM #OLE AND #OLE    ` 
  ARE CORRECTED TO ACCOUNT FOR THE MEAN INCIDENCE WITHIN THE IMAGED SWATH  THERE IS NO ATTEMPT TO CORRECT FOR SLOPES LOCALLY WITHIN THE SWATH TO THE PIXEL LEVEL !N ALTERNATIVE IS TO DENOTE THE MAGNITUDE 
 697-708, September, 1979.  12. Graham, L. 
 It  applies to a fan beam, or to a pencil beam if the target passes through its center. If the target  passes through any other point of the. pencil beam, the maximum signal received will 11ot  correspond to the signal from the beam center. 
 Theautocorrelation function, oroutputofthematched filter,isshownin(b).Therearesix equaltime-sidelobes toeithersideofthepeak,eachatalevel-22.3dBbelowthepeak.In(c) (a) (b) 13rI-r0r 1-----.-.---T----------1 ...------- T------.-1 Inputto1L generate transmit waveformInputfor matched ftlter (c) Fillermatched topulseof widthr Figure11.19(0)Example ofaphase-coded pulsewith13equatsubdivisions ofeitherDO(+)or180"(- ) phase.ThisisknownasaBarkercodeoflength13.(b)Autocorrelation function of(0),whichisan approximation totheoutputofthematched filter.(c)Blockdiagram ofthefilterforgenerating the transmitted waveform of(0)withtheinputontheleft.Thesametappeddelaylinecanbeusedasthe receivermatched filterbyinserting thereceived echoattheopposite end(theright-hand sideofthedelay lineinthisillustration).. FXI RACI ION OF INFORMAT1ON AND WAVEFORM DESIGN 429  Table 11.2 Barker codes  ('ode lerigtli C'ode elernerits Sidelobe level. dB  - -  t -, t + - 6.0  t t- - 9.5  1 t - 4.1 kt- - 12.0  III I - 14.0  III t- - 16.9  I I I I t- -- 20 8  IIII~ t I -t-t - 22.3  . 
 (a) Vane type; (b) rising sun, with  alternate slot lengths.  Fig. 6.3. 
 Clerici, “Curved edge modification of  compact range reflector,” IEEE Trans ., vol. AP-35, pp. 176–182, February 1987. 
 J. Frazer and Y . I. 
 2.3  2.2 Range Equations  ....................................................  2.4  Radar Transmission Equation  ............................  2.4  Maximum-Range Equation  ................................. 
 Natl. Conf. on Aeronaut. 
 STATE  TRANSMITTER IS THE 53 .AVYS !.303 
 . Radar System Engineering  Chapter 4 – Information Content of Radar Signals  20     Three magnitudes are used for resolving the timestamp, as is shown in Figure 4.1:   - Amplitude A  → Pulse Modulation   → Pulse Radar  - Frequency f  → Frequency Modulation  → FM- CW Radar   - Phase ϕ   → Phase Modulation  → Phase Interferometer     Figure 4.1  Procedure to measure range: T = Period duration, B = Frequency shift, Δf  =  frequency difference, Δt time difference, τ = Pulse duration.   With pulse Radar the time difference can be measured directly. 
 TION PERFORMANCE &REQUENCY DIVERSITY LOOK 
 The radar operates at a frequency of 9500 MHz with a magnetron transmitter that has a peak power output of 100 kW. The antenna is a slotted waveguide that is 11 m long and 4 cm high. Cosmos 1500 has demonstrated many significant capabilities, including (1) routine automatic picture transmission of SLR images of earth; (2) mapping of inhomogeneities of Antarctic and Greenland ice cover that were previously not detected; (3) radar images of polar regions of multiyear and first-year ice zones; (4) mapping of elongated zones of ice-cover continuity disturbances; (5) tracking of sea-ice drift by using a series of radar images of the same water area; (6) detection of oil slicks, wind fields, and currents; and (7) guidance of ships trapped in arctic ice during October-November 1983. 
 Because of cost and space constraints, a single display nor - mally acts as both radar and electronic chart. Theses displays are all effectively MFDs  and can, therefore, also be used as an electronic chart system without radar input. 22.7 INTEGRATION WITH AIS The maritime Automatic Identification System26 (AIS) is a target information system  that performs similar functions to airborne Secondary Surveillance Radar (SSR), such  as Air Traffic Control Beacon System (ATCRBS) and Identification Friend or Foe  (IFF). 
 Systematic errorsinclude (1)errorinthezeroreference oftheencoders thatindicate theorientation oftheradaraxes, (2)misalignment oftheelevation axiswithrespecttotheazimuth axis(nonorthogonality), (3)drooporflexingoftheantenna andmountcausedbygravity,(4)misalignment oftheradar withrespecttotheelevation axis(skew'),(5)noncoincidence oftheazimuth planeofthemount tothelocalreference plane(mislevel), (6)dynamic lagintheservosystem,(7)finitetransit timethatresultsinthetargetbeingatadifferent position bythetimetheechoisreceived hy theradar,and(8)bending andadditional timedelayofthepropagation pathduetoatmo­ sphericrefraction. Aboresight telescope mounted ontheradarantenna permitscalibration ofthemechani­ calaxisoftheantenna withrespecttoastarfield.Thiscalibration accounts forbiasin azimuth andelevation, mislevel, skew,droop,andnonorthogonality. Tracking avisiblesatel­ litewiththeradarpermitstheposition oftheRFaxis relativetothemechanical (optical) axis tobedetermined. 
 The frequency forreception and that fortransmis- sion arenearly the same; they arenot identical because ofthe different voltages and transit times involved atthetwo clifferen tlevels ofoperation. Figure 8.10 shows two readily realizable cycles ofvariation offrequency. SEC.87] INTERR~A TIONCODES 263 with time. 
 J. A.: Large Radomes, chap. 5 of" Microwave Scanning Antennas, vol. 
 However, in  systems with large bandwidths (short compressed pulses), the timing jitter require - ments become significant and may require special clock regeneration circuitry at key  system locations. Effect of Quantization Noise on Improvement Factor.  Quantization noise,  introduced in the A/D converter, limits the attainable MTI improvement factor. 
 Steunou, E. Caubet, L. Phalippou, L. 
 E  20 - 10 -Sparse  woods Wooded hills  10 knots Wooded hills Seo echo Rain  40 knots Chaff  0'------'---'---'--'-_._~~---~~~~_._~~~--~-~--'--~~~  0 001 01 1·0 10  c,11 = rms velocity spread, mis  Figure 4.30 Plot of double-canceler clutter improvement factor [Eq. (4.26)] as a function of uv = rms  velocity spread of the clutter. Parameter is the product of the pulse repetition frequency (/p) and the  radar wavelength (,l). 
 WIDTH  WHICH IS P 4HE 3. IS THE VALUE AT THE CENTER OF THE BEAM AFTER 0 3WERLING Ú )%%%  . 
 Scan, conical) Connectors coaxial-line, 396 type N,397 Contrast ofPPI display (see PPI dis- plays, contrast of) Control (see Speed; Voltage; etc.) Controllers, 235 Corner reflector, 67 Cosecant-squared antenna (see Antenna, cosecant-squared) Counter, V.A.,80 Coupling, for coaxial line (see. Line, ‘coa;ial, coupling for) waveguide (see Waveguide, choke coupling for) Coverage, high, 50 low, 50 Coverage diagram, 54 Crest factor, 557 Cross section, ofaircraft, 76 experimental, 78 corner reflector, 67 cylinder, 66 effective receiving, 20 flatsheet, 65 propeller modulation of,76 radar, 21,63 scattering, ,21 from sphere, 64 segment ofsphere, 66 ofships, 80 CRT (seeCathode-ray tube) Crystal, converter-type, specifications of, 414 formixer, 412-414 noise temperature of,413 C-scope, 173 Cutparaboloid, 272 C-wradar systems (SeealsoRadar system, c-w) CXAM, 180 Cylindrical reflector, 276. 740 RADAR SYSTEM ENGINEERING D Dark-trace screens, 483 Dark-trace tube, 22o Data stabilization, 311–312 Data tramsmiesion, 283 potentiometers for, 487 variable condensers for, 489 variable transformers for, 487 autosyns, 487 resolvers, 487 selsyns, 487 synchros, 487 Data transmitter, angle, 48&492 D-creetorer, 503 Deck-tilt error (see Error, deck-tilt) Decoder, triple-pulse, 687 Delay line, characteristic impedance of, 671 folded mercury, 668 fused quartz, 669 laboratory type of,633 liquid, 667-669 mercury, design constants for, 670 supersonic, 667–672 Delay-line attenuation, 670 Delay-line circuits, 634 Delay-line driving circuits, 672 Delay-line end cells, 669 Delay-line signal circuits, 672-675 Delay-line trigger circuits, 67$677 degenerative, 675 regenerative, 676 Delaytank,liquid,669 Detection, aural,134 Detector, balanced, forMTI,666 second, 449 Dicke, R.H.,32 Diffraction cr08s8ecti0n, 69 DMraction phenomena atmedium wave- length, 715 Diode, biased, 504 charging, 383 Diode limiters, 504 Display, double-dot, 174 one-dimensional, 164–167 three-dimensional, 174175 two-dimensional, 167–174 pip-matching, 167 sector, 168 (See abo Indicator)Doppler effect, 125, 629 Doppler frequency, 128 Doppler system, bandwidth of,135 pulsed, 630 pulse-modulated, 150-157 range-measuring, 139-143 simple, 132–139 Double-dot display (see Display, double- dot) Double-tuned circuit, 446 DuBridge, L.A., 16 Duct, 56-58 Dueppel, 82 Duplexing, 407411 Dynamotors, 57%581 booster armature voltage regulation of, 560 dual-output, 579 triple-output, 579 E Eagle (see AN/APQ-7 scanner) Eccles, W.H., 497 lIkcles-Jordan circuit, 497 Echo, from rain, 81 fluctuations of,83 reduction of,84 second time around, 117 from storm, 81 Eclipse, 559, 574 Effective height, ofship target, 80 Eicor Inc., 579 Eighth-power region, 51 Electromagnetic energy storage, 356 Electronic efficiency, ofmagnetron, 345 Electronic switches, 503–510 Electrostatic deflection ofbeam ofCRT (see Cathode-ray tube, electrostatic deflection of) Electrostatic energy storage, 356 Electrostatic focusing of CRT (see Cathode-ray tube, electrostatic fo- cusing of) Elsey, Howard M., 561 Emslie, A.G., 640, 645 Error, deck-tilt, 309 inaircraft, 311 E-scope, 173 Evans Signal Laboratory, 17. 
 If the periods of the  staggered waveforms have the relationship nl /TI = n2 /& = . = nN/TN, wherenl,n2, ..., n~  are integers, and if UB is equal to the first blind speed of a nonstaggered waveform with a  MTJANDPULSE DOPPLER RADAR115 w1.0 V160.8- 0. ~0.6 .~0.4 0 di0.2n: 03/T, 4/T, 0 liT, 21T, rrequellcy (a) lO-w <I>6 0.8- 0. 
 The use of a three-pulse canceler ahead  of the fi1ter:bank eliminates stationary clutter and thereby reduces the dynamic range required  8 -pulse doppler Weighting  filler bank and  magnitude  Zero velocity Clutter mop  filter Mogni t ude .recursive  filter  Figure 427 Simple block diagram of the Moving Target Detector (MTD) signal processor.  MTIANDPULSEDOPPLER RADAR127 4.7EXAMPLE OFANMTIRADAR PROCESSOR TheMovingTargetDetector (MTD)isanMTIradarprocessor originally developed bythe MITLincolnLahoratory fortheFAA'sAirportSurveillance Radars(ASR).42-44 TheASRisa medium range(60nmi)radarlocatedatmostmajorUnitedStatesairports.Itoperates atS band(2.7--2.9GHz)withapulsewidthoflessthan1ps,a1.4°azimuth beamwidth, anantenna rotation ratcoffrom12.5to15rpmdepending onthemodel,aprffrom700to1200Hz (1030Hztypical),andanaveragepoweroffrom400to600W.TheMTDprocessor employs severaltechniques fortheincreased detection ofmovingtargetsinclutier.Itsimplementation isbasedontheapplication ofdigitaltechnology. Itutilizesathree~pulse canceler followed by an8-pulseFFTdoppler filter-bank withweighting inthefrequency domaintoreducethefilter sidelobes, alternate prrstoeliminate blindspeeds,adaptive thresholds, andacluttermapthat isusedindetecting crossing targetswithzeroradialvelocity. 
 The sampled spectra of the two portions of the signal do not over - lap; the sampled signal is not aliased. As will be described in more detail later in the  chapter, this technique, bandpass sampling,  is a powerful tool that allows a relatively  high-frequency signal to be sampled by a relatively low-performance digitizer, which  can result in considerable cost savings. Figure 25.6 a shows the spectrum of a more general complex signal of bandwidth  B before sampling. 
 73–78, July 1965. 14. A. 
 SPEED APPLICATIONS THAN ))2 FILTERS  WHICH TYPICALLY REQUIRE THE COMPU 
 A proper blanking logic allows this signal to pass. Targets and/or jammers J situated in the sidelobes give small main but large auxiliary signals so that these targets are suppressed by the blanking logic. It is assumed that the gain GA of the auxiliary antenna is higher than the maximum gain Gsl of the sidelobes of the radar antenna. 
 1957.  19. Ala kc. 
 Howard, and A. M. King: Phenomena of Scintillation Noise in Radar  Tracking Systems. 
 ERATE TRANSMISSION OR RETRANSMISSION OF AMPLITUDE  FREQUENCY  PHASE  OR OTHERWISE MODULATED INTERMITTENT  #7  OR NOISE 
 Headrick. R. W. 
 (A further description  as to why the log-FTC receiver is CF AR when the input is Rayleigh clutter is given m  Sec. 13.8.) . 488 INTRODUCTION TO RADAR SYSTEMS  Sea clutter has a Rayleigh pdf when the resolution is low. 
 Equipment essentially like that just described has had agreat deal ofuse and initsfinal form has proved satisfactory. Anentire system using this method isdescribed inSec. 17.16. 
 ING THE EFFECT OF THE SURFACE REFLECTION 4HE NONCOHERENT VOLUME RETURN IS IRREDUCIBLE   HOWEVER  AND IS NOT INFLUENCED BY THE ORIENTATION OF THE COLUMN 4HE VOLUME RETURN  OF SUITABLE FOAM COLUMN SUPPORT MATERIALS IS OF THE ORDER OF   r  
 Any use is subject to the Terms of Use as given at the website. Source: RADAR HANDBOOK. 24.2  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 24 The chapter ends with an approach to the problem of evaluating the efficacy of  ECCM and ECM techniques (Section 24.12). There is a lack of theory to properly quan - tify the endless battle between ECCM and ECM techniques. 
 POINTING COMPUTATIONS  ELECTRONIC DRIVERS AND PHASE SHIFTERS  OR SWITCHES  AND ALL THEIR INTERCONNECTIONS &REQUENT INDICATIONS THAT THE ANTENNA SYS 
 The lag error, in  this case, is dependent on many factors, including the accuracy of the value of angle  sensitivity used to convert error voltages to angular error, the size of the previous  tracking error, and the time interval between looks. FIGURE 9.15  (a) Closed-loop frequency-response characteristics of two  servosystems and ( b) their corresponding time response to a step input ch09.indd   19 12/15/07   6:07:22 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. 
                  
 tures the range-tracking circuits. The deception signal is then progressively de- layed in the jammer by using an RF memory, thereby "walking" the range gate off the actual target (range-gate pull-off, or RGPO, technique). When the range gate is sufficiently removed from the actual target, the deception jammer is turned off, forcing the tracking radar into a target reacquisition mode.12 Another DECM technique is called inverse-gain jamming; it is used to capture the angle-tracking circuits of a conical-scan tracking radar.8 This technique re- peats a replica of the received signal with an induced amplitude modulation which is the inverse of the victim radar's combined transmitting and receiving antenna scan patterns. 
 f- transmitter Tirn~ng signal  r J.  Average Range  frequency --+  counter fo( l -flF  Sidebond  filter  fo(tI -/I~  Figure 3.13 Block diagram of FM-CW radar using sideband superheterodyne receiver.  ,/if:. 
 Rutledge, N. Cheng, R. York, R. 
 Any use is subject to the Terms of Use as given at the website. Phased Array Radar Antennas. 13.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 13 power, the vector sum of their contributions, added at a great distance as a function of  q, is the radiation pattern  E e eaj s j s( ) [( / )(/ )sin ( / (( /)siqq= +− 1 22 2 2 2 π λ π λ n n]q  where q  is measured from the broadside direction. Normalizing, to get unity ampli - tude when q  = 0, and simplifying give  Es a( ) cos s in q q =  πλ (13.1) The absolute value of Ea (q  ) is plotted in Figure 13.4 as a function of p (s/l) sin q. 
 has had wide application. Historically, the early radar experimenters worked almost  exclusively with continuous rather than pulsed transmissions (Sec. 1.5). 
 10.10  RADAR HANDBOOK 6x9 Handbook  / Radar Handbook / Skolnik / 148547-3 / Chapter 10 If a TWT using a coupled-cavity circuit is cathode-pulsed (Section 10.7), there is  an instant during the rise and fall of voltage when the beam velocity becomes synchro - nous with the cutoff frequency (the so-called p  mode) of the microwave circuit, and  the tube can generate oscillations. These oscillations at the leading and trailing edges  of the RF output pulse have a characteristic appearance on a power-time presentation  that has given them the name rabbit ears . Only in rare cases has it been possible to sup - press these oscillations completely. 
 The parabola is well suited for microwave  antennas because (I) any ray from the focus is reflected in a direction parallel to the axis of  the paraboia atid (2) the distance traveled by any ray from the focus to the parabola and by  reflection to a plane perpendicular to the parabola axis is independent of its path. Therefore a  point source of energy located at the focus is converted into a plane wavefront of uniform  phase.  The basic parabolic contour has been used in a variety of configurations. 
 Figure 15.3 shows thefindings ofamore recent (July 1945) survey covering 10-cm ship radars; itindi- cates that there had been nochange forthebetter. Such serious deficiencies inactual field radar performance emphasize the fact that the use oftest equipment tomeasure performance and to trace down thecauses ofimpaired performance had notbeen incorporated into routine maintenance practice formost radar sets atthe end ofthe 01Lo 10 20 30 40 Oedels below ratedperformance?%6* z ~4 2 22 0k o 10 20 30 40 Oeabels below rated performance FIG. 15.2.—Radar performance surveys, FIG. 
 arid scan time is a constant. Eq. (2.57). 
 Footnotes within Chapter V of SOLAS identify the recommended IMO perfor - mance standards with which the equipment should conform. IMO has had recom - mended radar performance standards2 since 1971, published as annexes to IMO  Resolutions. However, by 1980, radar manufacturers were reporting difficulties  because differing interpretations by national maritime administrations meant that  radars had to be specifically designed to meet individual flag State requirements. 
 P. D. Spudis, C. 
 FIELD COMPONENTS PARALLEL  AND PERPENDICULAR TO THE PLANE OF SCATTERING IN TERMS OF THE COMPONENTS OF THE INCI 
 withinthelimitsoftheantenna coverage. The monostatic-radar signalincreases quiterapidlyasthetargetapproaches theradarbecauseof theinverserelationship between theechosignalPrandR4[Eq.(14.35)]. Thebistaticradar signalalso.increases aseitherendofthefenceisapproached sincetheechosignalisinversely proportiollal toDfD;[Eq.(14.36)]. 
 468-480, April, 1969.  106. Konrad, T. 
 Kim, “Remote sensing by radar,” in Wiley Encyclopedia of Electrical and  Electronics Engineering Online , J. Webster (ed.), New York: John Wiley & Sons, Inc., 1999. 166. 
 The factor F P includes the energy loss along the ionospheric path, the  mismatch loss due to a change in polarization caused by the ionosphere, ionospheric focusing  gain or loss, and losses due to the dynamic nature of the path.22•23 The receiver noise N0  includes the ambient noise radiated by natural sources (chiefly lightning discharges from  around the world) as well as the combined interference from the many users of the HF band. It  is the latter ,vhich generally determines system sensitivity at HF. The processing ·time T.: is  included to emphasize that an 0TH radar is usually a doppler-processing radar that requires a  dwell time of T, seconds if a frequency resolution of 1/T.: hertz is to be achieved. 
  ÊÊ - 976 
 §S PULSE WITH PEAK POWER OF  K7 TO PROVIDE A SINGLE 
 Kerr, D. E. (ed.):" Propagation of Short Radio Waves," MIT Radiation Laboratory Series, vol. 
 SEC. 13.20] RESOLUTION ANDCONTRAST 549 betaken as180. On arange sweep oflength Rnautical miles, the number ofradar pulse lengths resolvable inprinciple is12.2R/T, where 7 isthe pulse length inmicroseconds. 
 ÓÈ°£{  2!$!2 (!.$"//+  FROM THE %ARTHS SURFACE AND THE ATMOSPHERE  IE  FREE SPACE &REE SPACE IS DEFINED AS A  REGION WHOSE PROPERTIES ARE ISOTROPIC  HOMOGENEOUS  AND LOSS 
 This loss in  integration efficiency is caused by the nonlinear action of the second detector, which converts  some of the signal energy to noise energy in the rectification process.  (2.30)THERADAR EQUATION 29 change insignal-to-noise ratioismuchgreaterthanthisforagivenchangeindetection probahility, asdiscusscd inSec.2.8.)/\lso,thesignal-to-noise ratiorequired fordetection is notasensitive function ofthefalse-alarm time.Forexample, aradarwithaI-MHzbandwidth requires asignal-to-noise ratioof14.7dBfora0.90probability ofdetection andaIS-min false-alarm limc.IfIhcfalsc-alarm limewereincreased fromISminto24h,thesignal-to-noise ratiowouldheincreascd to15.4dB.Ifthefalse-alarm timewereashighasIyear,therequired signal-tn-lloise ratiowouldhe16.2dB. 2.6INTEGRATION OFRADAR PULSES Therclatiollship hetwecn thesiglwl-to-IJOisc ratio,theprobability ofdetection, andtheproh­ abilitynffalsealarmasgivclIinFig.2.7appliesforasinglepulscQnly. 
 thelosses incurred inpropagating millimeter wavelengths through fog,haze,andsmokeislessthanat infrared orvisiblewavelengths. Another example whereaparticular property ofmillimeter-wave radarhasbothfavor­ ableandunfavorable aspectsisthatofthedoppler frequency shift.ItwasshowninSec.3.1 thatthedoppler frequency shiftwasproportional tathecarrier(rf)frequency. Thisresultsin moreaccurate relative-velocity measurements withmillimeter wavelengths thanatlower frequencies. 
 HOP PROPAGATION CAN REACH GREATER RANGES  &)'52%  4HE VARIATION OF THE MONTHLY MEDIAN SUNSPOT NUMBER SINCE    THE YEAR OF THE FIRST OPERA 
 K-SVD: An Algorithm for Designing Overcomplete Dictionaries for Sparse Representation. IEEE T rans. Signal Process. 
 In the real data scenario, the rheological parameters of a stretch of highway (namely, the Lungui Highway in Foshan, China) are obtained, and the time-series subsidence over the period of June 2014 to December 2015 is investigated using TerraSAR X imagery. 2. Time-Series Modeling Considering Rheological Parameters2.1. 
 vol.10.pp.RR-95.February. 1978.SeealsosametitleandauthorinIEEEEASCON '76 Record, pp.30-Ato30-H. 96.Trunk.G.V..andJ.D.Wilson: TrackInitiation inaDenseDetection Environment, NavalResearch Lanoratory (Washington. 
 If the radar frequency were 10 GHz, PRF 1 kHz, and ground speed  580 kt, the notch would have to be held within 0.29 kt or 0.005 Vg. Because of these requirements and the width of the platform-motion spectrum, stag - ger PRF systems must be chosen primarily on the basis of maintaining the stopband  rather than flattening the passband. Similarly, higher-order delay-line filters (with or  without feedback) are synthesized on the basis of stopband rejection. 
 10.5 SAW transducer types, (a) Dispersive output, (b) Both input and output dispersive, (c) Dispersive reflections. traverse the crystal length. Figure 10.5c shows a reflection-array-compression (RAC) approach10 which essentially doubles the achievable pulse length for the same crystal length. 
 Itisthen possible touselonger persistence without blurring. However, since observation ofthefrozen display is usually part ofthe“tracking” operation which controls theremoval ofthemotion, thepersistence must notbesolong thatitreduces theeaseofdetecting small changes intarget position.. SEC. 
 The rms noise power  at the output is smaller than the peak power from a point target by the factor BT. A detection  threshold is set somewhere within this range of possible amplitude to allow point targets that  are larger than the background to be detected. This dispersive CFAR may be placed either  before or after the matched Alter. 
 FERING ONLY BY LESS THAN  D" OVER WIDE RANGES OF 0$  0FA  AND N L "ECAUSE THE SIGNAL RETURN OF A SCANNING RADAR IS MODULATED BY THE ANTENNA PATTERN  TO  MAXIMIZE THE  3. WHEN INTEGRATING A LARGE NUMBER OF PULSES WITH NO WEIGHTING IE   !I      ONLY  OF THE  PULSES BETWEEN THE HALF 
 #OUNTERMEASURES   .ORWOOD  -! !RTECH (OUSE   )NC     3PECIAL )SSUE ON ELECTRONIC WARFARE  )%% 0ROC  VOL   PT &  NO   PP n  *UNE   7 ! $AVIS  h0RINCIPLES OF ELECTRONIC WARFARE 2ADAR AND %7 v  -ICROWAVE *  VOL   PP n   n  &EBRUARY    , " 6AN "RUNT   4HE 'LOSSARY OF %LECTRONIC 7ARFARE   $UNN ,ORING  6! %7 %NGINEERING  )NC    $EPARTMENT OF $EFENSE  *OINT #HIEFS OF 3TAFF   $ICTIONARY OF -ILITARY AND !SSOCIATED 4ERMS   *#3  0UB 
  D" WITH A PROBABILITY OF   DETERMINE THE REQUIRED PROBABILITY ON  ANY ONE GIVEN SIDELOBE      0 ; SIDELOBES    D"=  4HEN        
 SPECIFIC CONSTRAINTS ON FREQUENCY IN ADDITION  TO PROPAGATION CON 
 showed slant range. On H 2S Mk. II and ASV Mk. 
 Decker, J. J. Sojka,  and R. 
 ch20.indd   62 12/20/07   1:17:05 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. HF Over-the-Horizon Radar. 
 Detailed Design ofthe AN/APS-10.-With these major design decisions taken, thedetailed components design oftheAN/APS-10 remained. No attempt will bemade todiscuss the many interacting decisions that determined the design ofthe components ofthe set; FIG,159.-Units ofAN/APS-10. only thefinal result will bepresented, and anattempt made torationalize itinterms ofthe considerations ofSec. 
 SHIFTER CONFIGURATIONS  AFTER , 3TARK ET AL   A  SWITCHED 
 The A/D converter has been, in the past, one of the critical parts of the MTI signal  processor. It must operate at a speed high enough to preserve the information content of the  radar signal, and the number of bits into which it quantizes the signal must be sufficient for the  precision required. The number of bits in the AID converter determines the maximum inl-  provement factor the MTI radar can achie~e.~.~~.'~ Generally the AID converter is designed to  cover the peak excursion of the phase detector output. 
 The angle-error detector, assumed to be a product detector, has an output ld = *!icose where \e\ is the magnitude of the angle error voltage. Phases are adjusted to pro- vide O or 180° on a point-source target. The resultant is "l= ±4il Complex targets can cause other phase relations as a part of the angle scintilla- tion phenomenon.3 The above error voltage proportional to the ratio of the dif- ference signal divided by the sum signal is the desired angle-error-detector out- put, giving a constant angle error sensitivity.3 With limited AGC bandwidth, some rapid signal fluctuations modulate \e\9 but the long-time-average angle sensitivity is constant. 
 TO 
 P. McGarty, “Maximum-likelihood detection of unresolved targets and  multipath,” IEEE Trans ., vol. AES-10, pp. 
 OF 
 If the compression rate is high, the consistency is more obvious. However, by applying the proposed approach, reconstruction is performed through multi-channel joint sparsity, so as to ensure that the scattering points are at the same pixel of the images from different channels, which is more favorable for extraction of target height information. T able 5. 
 Angle noise causes a change with time in the apparent  location of the target with respect to a reference point on the target. This reference  point is usually chosen as the center of “gravity ” of the reflectivity distribution along  the target coordinate of interest. The center of gravity is the long-time-averaged track - ing angle on a target. 
 MAP MODE 4HE RESULT IS LARGER DOPPLER BANDWIDTH  HENCE ENHANCED AZIMUTH RESOLU 
 TION HAS ITS OWN UNIQUE IMPLICATIONS FOR SYSTEM DESIGN 4HE HIGHLIGHTS ARE REVIEWED IN THE FOLLOWING PARAGRAPHS 3EA 
 PS-32,  pp. 1109–1118, June 2004. 12. 
 ( / ) Ai i (16.23 b) where Ai and qi are constants that differ for the near-vertical and midrange regions.  Figure 16.23 shows an example of this variation. No theory gives exactly this result,  ch16.indd   29 12/19/07   4:55:56 PMDownloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2008 The McGraw-Hill Companies. 
 Under these assumptions a reduction of up to 20 dB can be achieved.  The creation of a stealth object with materials adapted to the free -space wave- impedance, according to Equation  (11.26), offers no advantages for loss- less materials, since only the phase velocity in the mat e- rial is lowered.  Additionally would the material still have to absorb, since otherwise a refle c- tion takes place on the other side.